2024/09/25 更新

写真a

ヨシダ トモコ
吉田 朋子
YOSHIDA, Tomoko
所属
大学院工学研究科 総合エネルギー工学専攻 エネルギーシステム工学 教授
大学院担当
大学院工学研究科
学部担当
工学部 エネルギー理工学科
職名
教授

学位 1

  1. 工学博士

研究分野 6

  1. その他 / その他  / 原子力学

  2. その他 / その他  / 構造・機能材料

  3. その他 / その他  / 触媒・資源化学プロセス

  4. その他 / その他  / 無機工業材料

  5. その他 / その他  / 機能物質化学

  6. その他 / その他  / 物理化学

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現在の研究課題とSDGs 2

  1. 量子線照射により発現する固体機能に関する研究

  2. 固体材料の照射損傷に関する研究

経歴 9

  1. 名古屋大学   大学院工学研究科総合エネルギー工学専攻   教授

    2024年4月 - 現在

  2. 大阪公立大学   人工光合成研究センター   教授

    2022年4月 - 2024年3月

  3. 大阪公立大学   人工光合成研究センター   副所長

    2022年4月 - 2024年3月

  4. 大阪市立大学   人工光合成研究センター   教授

    2020年4月 - 2022年3月

  5. 大阪市立大学   人工光合成研究センター   副所長

    2015年4月 - 2022年3月

  6. 大阪市立大学   複合先端研究機構   教授

    2015年4月 - 2020年3月

  7. 名古屋大学   エコトピア科学研究所   准教授

    2009年4月 - 2015年3月

  8. 名古屋大学   工学研究科   助教授

    2003年7月 - 2009年3月

  9. 名古屋大学   工学研究科   助手

    1996年6月 - 2003年6月

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学歴 3

  1. 京都大学   工学研究科   分子工学

    1993年4月 - 1996年3月

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    国名: 日本国

  2. 京都大学   工学研究科

    1991年4月 - 1993年3月

  3. 京都大学   工学部   石油化学科

    1987年4月 - 1991年3月

所属学協会 7

  1. 日本分析化学会

    2018年4月 - 現在

  2. 日本原子力学会

    1996年4月 - 現在

  3. 触媒学会

  4. 日本金属学会

  5. 日本放射光学会

  6. 日本希土類学会

  7. 日本化学会

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受賞 6

  1. 女性Analyst賞

    2023年7月   日本分析化学会  

  2. 教員活動表彰(研究の部)

    2019年6月   大阪市立大学  

  3. 岡村賞(女性研究者特別賞)

    2017年12月   大阪市立大学  

  4. International Symposium on Creation and Control of Advanced Selective Catalysis, Best Poster Presentation

    2008年7月   International Symposium on Creation and Control of Advanced Selective Catalysis  

  5. 日本顕微鏡学会第64回学術講演会女性研究者ポスター賞

    2008年5月   日本顕微鏡学会  

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    受賞国:日本国

  6. 触媒学会創立50周年記念大会優秀ポスター賞

    2008年3月   触媒学会  

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    受賞国:日本国

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論文 190

  1. X線吸収分光を基軸とした定量的局所構造・電子状態解析法の構築と複合型その場分析への展開

    吉田 朋子

    分析化学   73 巻 ( 7.8 ) 頁: 369 - 380   2024年7月

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    記述言語:日本語   出版者・発行元:公益社団法人 日本分析化学会  

    <p>固体触媒表面に存在するサブ・ナノメートルサイズの活性種を対象に,X線吸収分光を基軸とした定量的局所構造・電子状態解析法と,反応中の動的状態変化を理解するための複合型「その場」分析法を構築した.具体的には,X線吸収微細構造(XAFS)のうち,解析法が確立していなかったX線吸収端近傍構造(XANES)に対して,スペクトルの足し合わせや差し引きを利用した線形的解析法や,XANESの微細構造を内殻電子の連続状態への励起と,その他の吸収に分離する波形分離法を考案し,電子状態や配位対称性の異なる種を定量的に求める解析法を開発した.これらの解析法に,電子顕微鏡(TEM, EELS)を用いた高空間分解分析・イメージング技術などを導入し,活性種の空間分布を可視化する手法を構築した.また,<i>in-situ</i> XAFS, FT-IR, UV-VIS光吸収分光法を組み合わせた複合型「その場」分析も構築し,人工光合成や有機物分解反応を促進する固体光触媒の反応メカニズムを解明した.</p>

    DOI: 10.2116/bunsekikagaku.73.369

    CiNii Research

  2. Synthesis of Au-Nanoparticles on Carbon using Lysine as a Capping Agency in a Gas Diffusion Electrodes Cell for Electrocatalytic CO<sub>2</sub> Reduction 査読有り

    Yamamoto, M; Komoguchi, K; Koyama, F; Tanabe, T; Yoshida, T

    CATALYSIS LETTERS   154 巻 ( 6 ) 頁: 2648 - 2657   2024年6月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Catalysis Letters  

    We have prepared a membrane electrode assembly (MEA) consisting of Au nano particles (AuNPs) dispersed on Ketjen black (a carbon conductor: C) and Nafion (a proton conductor) as a cathode catalyst and IrO2 as an anode catalyst for electrocatalytic CO2 reduction in a gas diffusion electrodes cell. With using lysine as a capping agency, we have succeeded to make MEA first time. MEA with the area of 1 cm2 showed good performance in electrocatalytic CO2 reduction giving the CO production rate of 78.5 μmol/h with a Faraday efficiency of 81.3% and a current density of 5.2 mA/cm2 at maximum under the cell voltage of −2.2 V. The particle sizes of synthesized Au-NPs were divided into two groups of around 30 nm and a few nm. The formation of the latter was assisted by the capping effect of lysine and enhanced the electrocatalytic activity. However, at the present condition for AuNPs synthesis, appearance of 50 nm sized particles was unavoidable. Suppression of their formation would significantly enhance the catalytic activity and the present type of membrane assembly has great potential for a practical use. Graphical Abstract: (Figure presented.)

    DOI: 10.1007/s10562-023-04538-1

    Web of Science

    Scopus

    その他リンク: https://link.springer.com/article/10.1007/s10562-023-04538-1/fulltext.html

  3. Effects of Al<sub>2</sub>O<sub>3</sub> and MgAl<sub>2</sub>O<sub>4</sub> Support on Photocatalytic Activity of Ga<sub>2</sub>O<sub>3</sub> in CO<sub>2</sub> Reduction with Water 査読有り

    Ichikawa, K; Aoki, T; Akatsuka, M; Yamamoto, M; Tanabe, T; Yoshida, T

    CATALYSIS LETTERS   154 巻 ( 5 ) 頁: 2008 - 2022   2024年5月

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    担当区分:責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Catalysis Letters  

    It is known that photocatalytic activity of Ga2O3 on CO2 reduction with water is enhanced by employment of a support. However, the role of the support is not understood well. We have investigated the roles of the support on the photocatalytic CO2 reduction with using Ga2O3 supported by Al2O3 and MgAl2O4 as catalysts. On the supports, loaded Ga2O3 exhibited different crystalline phases and morphologies depending on the amount of loaded Ga2O3 on the supports and the specific surface areas of the supports. The larger the SSA, the more dispersedly Ga2O3 particles were loaded and gave higher catalytic activity. The production rates of H2 and CO, the dominant products of the CO2 reduction, showed different crystalline phase dependence, i.e., H2 production was dominated on α-Ga2O3, while the CO production rate increased with increasing the γ-Ga2O3/α-Ga2O3 ratio and peaked at a certain γ-Ga2O3/α-Ga2O3 ratio. Two main conclusions derived are, (1) Ga2O3 particles dispersedly loaded as a few tens nm sized rods on the support significantly enhance the photocatalytic activity and (2) a new mechanism that on α-Ga2O3 water splitting is dominated and resultant H atoms reduce CO2 adsorbed on γ-Ga2O3 or the boundary of the two phases. Graphical Abstract: (Figure presented.)

    DOI: 10.1007/s10562-023-04424-w

    Web of Science

    Scopus

    その他リンク: https://link.springer.com/article/10.1007/s10562-023-04424-w/fulltext.html

  4. Establishment of Quantitative Local Structural/Electronic State Analyses Based on X-ray Absorption Spectroscopy and Development for Their Multiple<i> In</i><i>-situ</i> Analysis

    Yoshida, T

    BUNSEKI KAGAKU   73 巻 ( 7 ) 頁: 369 - 380   2024年

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  5. Photoelectrochemical properties of plasma-induced nanostructured tungsten oxide (vol 580, 151979, 2022)

    Feng, SY; Kajita, S; Higashi, M; Bieberle-Hutter, A; Yoshida, T; Ohno, N

    APPLIED SURFACE SCIENCE   599 巻   2022年10月

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    出版者・発行元:Applied Surface Science  

    The authors regret, the affiliation of Masanobu Higashi is wrong. The correct affiliation is updated as above. The authors would like to apologise for any inconvenience caused.

    DOI: 10.1016/j.apsusc.2022.153668

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  6. Photoelectrochemical properties of plasma-induced nanostructured tungsten oxide 査読有り

    Feng, SY; Kajita, S; Higashi, M; Bieberle-Hütter, A; Yoshida, T; Ohno, N

    APPLIED SURFACE SCIENCE   580 巻   頁: 151979 - 151979   2022年4月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Applied Surface Science  

    Helium (He)-induced nanostructured tungsten sheets were synthesized by He plasma irradiation under different plasma exposure durations. After calcination, nanostructured tungsten oxide samples were used as photoelectrodes to test photoelectrochemical (PEC) performance. The results showed that nanostructured WO3 photoanodes have higher PEC performance compared to the sample without nanostructures. The 15 min irradiated sample had the highest photocurrent density of 3.5 mA/cm2 under the thermodynamic potential of water oxidation (1.23 V vs. RHE). It was found that the oxide layer thickness and exposed crystal facet have a significant impact on PEC performance. The plasma synthesis technique has proved to be an effective method for preparing nanostructured WO3 photoelectrodes.

    DOI: 10.1016/j.apsusc.2021.151979

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  7. Fabrication of a stable CdS photoanode for photoelectrochemical CO<sub>2</sub> reduction under visible-light irradiation 査読有り

    Higashi, M; Tanaka, I; Amao, Y; Yoshida, T

    NEW JOURNAL OF CHEMISTRY   46 巻 ( 13 ) 頁: 5932 - 5938   2022年3月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:New Journal of Chemistry  

    Metal sulfides are promising visible-light photocatalysts for CO2 reduction. However, available sulfide photocatalysts are limited because of their instability in aqueous solutions under photoirradiation. In this study, we investigated the fabrication of a stable CdS photoanode for CO2 reduction. The CdS photoanode prepared by the chemical bath deposition method was subjected to N2 calcination, which significantly affected its stability. Calcination up to 300 °C did not significantly change the surface morphology of the CdS photoanode. In contrast, the CdS electrode calcined at 400 °C had a smoother surface, with a lower surface area of the electrode, which consequently reduced the CdS photocorrosion. K2Cd[Fe(CN)6] (particle size ∼10 nm) was densely formed on the CdS surface via photocorrosion, and it effectively scavenged photogenerated holes in CdS and enabled the oxidation of [Fe(CN)6]4− to [Fe(CN)6]3−. Thus, we demonstrated stable CO2 reduction to CO over the CdS photoanode system in an aqueous solution at an applied bias of 0.5 V vs. Ag counter electrode under visible-light irradiation, along with the oxidation of [Fe(CN)6]4− to [Fe(CN)6]3−

    DOI: 10.1039/d1nj06073b

    Web of Science

    Scopus

  8. Synthesis of meso-porous α-Ga<sub>2</sub>O<sub>3</sub> from liquid Ga metal having significantly high photocatalytic activity for CO<sub>2</sub> reduction with water 査読有り

    Aoki, T; Ichikawa, K; Sonoda, K; Yamamoto, M; Tanabe, T; Yoshida, T

    RSC ADVANCES   12 巻 ( 12 ) 頁: 7164 - 7167   2022年3月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:RSC Advances  

    We have succeeded in synthesizing meso-porous α-Ga2O3 which shows significantly high photocatalytic activity for CO2 reduction with water. The sample was synthesized by hydroxidation of liquid Ga metal in water to obtain GaOOH and Ga(OH)3, followed by the calcination of the mixed hydroxides at 773 K for 1 hour which converted them to meso-porous α-Ga2O3. The nano-pores remained as the trace of the evaporation of water produced by the oxidation of the hydroxides during the calcination. The photocatalytic activity of the synthesized meso-porous α-Ga2O3 for CO2 reduction with water was as high as or higher than previous studies using various types of Ga2O3 with and without cocatalysts.

    DOI: 10.1039/d1ra09039a

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  9. Mixed phases of GaOOH/β-Ga<sub>2</sub>O<sub>3</sub> and α-Ga<sub>2</sub>O<sub>3</sub>/β-Ga<sub>2</sub>O<sub>3</sub> prepared by high energy ball milling as active photocatalysts for CO<sub>2</sub> reduction with water 査読有り

    Aoki, T; Yamamoto, M; Tanabe, T; Yoshida, T

    NEW JOURNAL OF CHEMISTRY   46 巻 ( 7 ) 頁: 3207 - 3213   2022年2月

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    担当区分:責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:New Journal of Chemistry  

    The photocatalytic activity of mixed phases of GaOOH/β-Ga2O3 and α-Ga2O3/β-Ga2O3 for CO2 reduction with water is investigated for the first time. GaOOH/β-Ga2O3 is synthesized by high energy ball milling of β-Ga2O3 in water, and α-Ga2O3/β-Ga2O3 are prepared by the calcination of GaOOH/β-Ga2O3 at 773 K. Both show higher activity for both CO2 reduction and the accompanying H2 evolution than the original material of β-Ga2O3. This is the first observation that the mixed phase of GaOOH/β-Ga2O3 has high photocatalytic activity. The H2 production rate is correlated to the specific surface area irrespective of the GaOOH/β-Ga2O3 and α-Ga2O3/β-Ga2O3 samples. The CO production rate for the mixed phase of α-Ga2O3/β-Ga2O3 is high, agreeing with the previous observation that the mixed phases or phase boundaries enhance the photocatalytic activity, and the CO production rate increases with the abundance rate of the α-Ga2O3 phase. Although the selectivity of the CO production remains low, it could be enhanced if an Ag cocatalyst was used. As an alternative mechanism of H2 production (H2 evolution) over the samples of GaOOH/β-Ga2O3 and α-Ga2O3/β-Ga2O3, a redox type reaction mechanism is proposed, in which the H2 evolution proceeds with the reduction of GaOOH to α-Ga2O3 emitting H2 and O2 by UV illumination, while α-Ga2O3 returned to GaOOH in water without illumination. Although some of the H2 thus evolved would cause CO2 reduction, CO2 reduction to CO requires specific active sites on the α-Ga2O3 surface.

    DOI: 10.1039/d1nj05245d

    Web of Science

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  10. Structural and Chemical State Analyses on Nitrided GaOOH as a Visible Light Response Photocatalyst

    Yamamoto, M; Kato, Y; Yagi, S; Tanabe, T; Yoshida, T

    E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY   20 巻 ( 1 ) 頁: 1 - 6   2022年2月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:公益社団法人 日本表面真空学会  

    To prepare photocatalysts promoting water splitting under visible light irradiation, GaOOH was nitrided by the calcination at a temperature ranging from 773 to 1273 K under a NH3 flow to produce nitrogen doped Ga2O3. X-ray diffraction measurements suggested that even under NH3 atmosphere dehydration of GaOOH to α-Ga2O3 occurred by calcining below 873 K. In the samples nitrided above 973 K, gallium nitride (GaN) phase started to appear and the crystallinity became better with increasing the nitriding temperature. In diffuse reflectance ultraviolet-visible measurements, absorption bands appeared in the visible light region after the nitrization, and the shift of the absorption edge with nitriding temperature suggested the formation of a new phase like gallium oxy-nitride. X-ray photoelectron spectroscopy and scanning transmission electron microscopy-electron energy-loss spectroscopy analyses revealed that oxygen atoms were distributed homogeneously and mixed with nitrogen atoms in the sample nitrided at 1173 K [referred as S(1173 K)] while oxygen atoms were mainly distributed at the surface of the sample nitrided at 1273 K [S(1273 K)]. The differences in the composition and chemical state near the sample surface closely related to the activity and stability during water splitting reaction under visible light irradiation between S(1173 K) and S(1273 K), i.e., the former sample provided stable H2 and O2 evolution while the latter sample was inactive and unstable.

    DOI: 10.1380/ejssnt.2022-003

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    CiNii Research

  11. Influence of Ag Clusters on the Electronic Structures of β-Ga<sub>2</sub>O<sub>3</sub> Photocatalyst Surfaces 査読有り

    Yamamoto, M; Kuwabara, A; Yoshida, T

    ACS OMEGA   6 巻 ( 49 ) 頁: 33701 - 33707   2021年12月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Omega  

    In order to understand the photocatalytic carbon dioxide reduction over Ag-loaded β-Ga2O3 photocatalysts, first principles calculations based on density functional theory were performed on the surface model of a Ag cluster-adsorbed β-Ga2O3 system. The stable adsorption structures of Agn (n = 1 to 4) clusters on the β-Ga2O3 (100) surface were determined. In the electronic structure analysis, the valence states of all Ag clusters mixed with the top of the O 2p valence band of Ga2O3, leading the Fermi level of Agn/β-Ga2O3 to shift to the bottom of the conduction band. It was also revealed that the unoccupied states of Agn clusters overlapped with the Ga unoccupied states, and occupied electronic states of Ag clusters were formed in the band gap. These calculation results corresponded to the experimental ones obtained in our previous study, i.e., small Ag clusters had strong interaction with the Ga2O3 surface, enhancing the electron transfer between the Ag clusters and the Ga2O3 surface. That is, excited electrons toward Agn clusters or the perimeter of Ag-Ga2O3 should be the important key to promote photocatalytic CO2 reduction.

    DOI: 10.1021/acsomega.1c04730

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    PubMed

  12. Real time measurements of UV-vis diffuse reflectance of silver nanoparticles on gallium oxide photocatalyst 査読有り

    Kitajima, D; Yamamoto, M; Tanabe, T; Yoshida, T

    CATALYSIS TODAY   375 巻   頁: 501 - 505   2021年9月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Catalysis Today  

    Ag loaded Ga2O3 photocatalysts are well known to be highly active for the CO2 reduction with water to CO. However, Ag changes its chemical state during the reaction, resulting in the decrease of its photocatalytic activity. To examine the chemical state change during the photocatalytic CO2 reduction, we have attempted a real time observation of the change in the chemical and physical states of Ag co-catalyst loaded on Ga2O3 by monitoring UV–vis reflectance spectra under the atmosphere simulating the photocatalytic CO2 reduction. In UV–vis spectra, two characteristic absorptions appeared at around 450 nm and 600 nm corresponding to resonance absorptions of localized surface plasmon (LSPR) of Ag nanoparticles (Ag-NPs) and Ag in metallic state. The LSPR absorption appeared as light irradiation started and grew with the time. It was revealed that Ag on Ga2O3 was initially in the oxidized state and reduced by the light irradiation to be Ag-NPs. Further light irradiation enlarged the size of Ag-NPs to be the metallic state especially under atmosphere with water. Under CO2 atmosphere, Ag-NPs remained small after further light irradiation. These results suggest that Ag initially loaded on Ga2O3 in the oxidized state was reduced to be dissolved as Ag+ in water and precipitated as Ag-NPs. Then, some of Ag-NPs aggregated to be larger Ag particles or in the metallic state. Such reduction process depends on gas species of the system, i.e. water promoted the formation of Ag-NPs while CO2 suppressed the formation Ag-NPs.

    DOI: 10.1016/j.cattod.2020.04.063

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  13. Enhanced photocatalytic ethylene decomposition with anatase-rutile mixed nanostructures formed by He plasma treatment 査読有り

    Shin Kajita, Kazuya Miyaguchi, Hirohiko Tanaka, Eriko Yasunaga, Tomoko Yoshida, Noriyasu Ohno

    Journal of Photochemistry and Photobiology A: Chemistry   418 巻   2021年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier B.V.  

    In order to realize high-performance titanium dioxide (TiO2) photocatalysts for ethylene decomposition, titanium (Ti) thin film samples with fiberform nanostructures were prepared by helium (He) plasma treatment. Then, the oxidation condition for ethylene decomposition were optimized in terms of the oxidation temperature and duration. It is shown that He plasma irradiation with Ti deposition followed by oxidation in the air formed anatase-rich TiO2. The rutile anatase transition temperature increased to higher than 1000 K on the He treated samples and the best photocatalytic performance is twice higher than that on TiO2 sample formed in a magnetron sputtering device. Helium plasma treatment induces vacancies, He clusters, and He bubbles together with formation of nanostructures. The results suggested that those morphology changes lead to the formation of stable anatase structure, which is likely the key factor for the enhancement of photocatalytic activity. Based on the obtained ethylene decomposition rate, we will discuss the necessary light source and amount of photocatalysts to keep vegetables fresh in a long-distance transport cargo.

    DOI: 10.1016/j.jphotochem.2021.113420

    Scopus

  14. Synthesis of a-Ga<sub>2</sub>O<sub>3</sub> by Water Oxidation of Metallic Gallium as a Photocatalyst for CO<sub>2</sub> Reduction with Water 査読有り

    Sonoda, K; Yamamoto, M; Tanabe, T; Yoshida, T

    ACS OMEGA   6 巻 ( 29 ) 頁: 18876 - 18880   2021年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Omega  

    We have succeeded to synthesize gallium oxide consisting of α-phase (α-Ga2O3) with the calcination of GaOOH obtained by a direct reaction of liquid Ga metal with water for the first time and found that α-Ga2O3 exhibits photocatalytic activity for CO2 reduction with water and water splitting as well. The calcination above 623 K converted GaOOH to α-Ga2O3, and the samples calcined at 723-823 K were well crystallized to α-Ga2O3 and promoted photocatalytic CO2 reduction with water, producing CO, H2, and O2. This is observed for the first time that α-Ga2O3 without a cocatalyst has shown very high photocatalytic activity for the conversion of CO2 to CO.

    DOI: 10.1021/acsomega.1c02088

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    PubMed

  15. The role of the shell in core-shell-structured La-doped NaTaO<sub>3</sub> photocatalysts 査読有り

    Sudrajat, H; Kitta, M; Ito, R; Yoshida, T; Katoh, R; Ohtani, B; Ichikuni, N; Onishi, H

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   23 巻 ( 14 ) 頁: 8868 - 8879   2021年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Physical Chemistry Chemical Physics  

    NaTaO3, a semiconductor with a perovskite structure, has long been known as a highly active photocatalyst for overall water splitting when appropriately doped with La cations. A profound understanding of the surface feature and why and how it may control the water splitting activity is critical because redox reactions take place at the surface. One surface feature characteristic of La-doped NaTaO3is a La-rich layer (shell) capping La-poor bulk (core). In this study, we investigate the role of the shell in core-shell-structured La-doped NaTaO3through systematic chemical etching with an aqueous HF solution. We find that the La-rich shell plays a role in electron-hole recombination, electron mobility and water splitting activity. The shallow electron traps populating the La-rich shell trap the photoexcited electrons, decreasing their mobility. The shallowly trapped electrons remain reactive and are readily available on the surface to be extracted by the cocatalysts for the reduction reaction evolving H2. The presently employed chemical etching method also confirms the presence of a La concentration gradient in the core that regulates the steady-state electron population and water splitting activity. Here, we successfully reveal the nanoarchitecture-photoactivity relationship of core-shell-structured La-doped NaTaO3that thereby allows tuning of the surface features and spatial distribution of dopants to increase the concentration of photoexcited electrons and therefore the water splitting activity. By recognizing the key factors that control the photocatalytic properties of a highly active catalyst, we can then devise proper strategies to design new photocatalyst materials with breakthrough performances.

    DOI: 10.1039/d1cp00375e

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  16. 第56回X線分析討論会報告

    吉田 朋子

    X線分析の進歩   52 巻 ( 0 ) 頁: 261 - 265   2021年3月

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    記述言語:日本語   出版者・発行元:公益社団法人 日本分析化学会 X線分析研究懇談会  

    DOI: 10.57415/xshinpo.52.0_261

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  17. Synthesis of nanometer-sized gallium oxide using graphene oxide template as a photocatalyst for carbon dioxide reduction 査読有り

    Sonoda, K; Yamamoto, M; Tanabe, T; Yoshida, T

    APPLIED SURFACE SCIENCE   542 巻   頁: 148680 - 148680   2021年3月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Applied Surface Science  

    Since the activity of semiconductor photocatalysts for CO2 reduction with water is still low, it is necessary to improve their activity. To do this, the optimization of particle size and crystal structure of the photocatalysts is one of the promising ways. In previous studies, we have reported that micro-particulate Ga2O3 deposited on Al2O3 support significantly improves the photocatalytic activity of CO2 reduction. However, it is quite difficult to synthesize nano-particulate Ga2O3 with high crystallinity by calcination at higher temperatures. In this work, we have tried to synthesize sheet-like nano-particulate Ga2O3 using graphene oxide (GO) as a template for the first time. After loading gallium butoxide on GO, it was calcined to oxidize the gallium butoxide into Ga2O3 and also to remove GO. Various spectroscopic analyses revealed that the synthesized materials were planar aggregation of nanometer-sized Ga2O3 particles (nsGa2O3), of which sizes and crystallinity could be controlled with the calcination temperature. The nsGa2O3 calcined at 1123 K was well crystallized and showed β-phase with a quite large specific surface area. Furthermore, Ag loaded nsGa2O3 calcined at 1123 K (Ag/nsGa2O3(1123 K)) showed very high photocatalytic activity for CO production in the photocatalytic CO2 reduction test in water including methanol under UV light irradiation. Thus, it is confirmed that the planar aggregation of nanometer-sized Ga2O3 significantly improves the photocatalytic activity of Ga2O3 on the CO2 reduction.

    DOI: 10.1016/j.apsusc.2020.148680

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  18. Increase in CO<sub>2</sub> reduction rate via optical near-field effect 査読有り

    Yatsui, T; Nakamura, Y; Suzuki, Y; Morimoto, T; Kato, Y; Yamamoto, M; Yoshida, T; Kurashige, W; Shimizu, N; Negishi, Y; Iida, K; Nobusada, K

    JOURNAL OF NANOPHOTONICS   14 巻 ( 4 )   2020年10月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Nanophotonics  

    To reduce the effects of global warming, visible and near-infrared light must be used more efficiently. Deep ultraviolet light (8 eV) is required for the direct dissociation of CO2 by light; however, the introduction of a metal complex has made it possible to realize CO2 reduction with visible light. We demonstrate that the optical near field (ONF) can increase the CO2 reduction rate. For this, we used gold clusters, because they can be a suitable source for ONFs, as their size and density can be controlled by the number of gold atoms. By attaching a metal complex near gold clusters with diameters of 1.0 to 1.3 nm, we confirm that the reduction rate of CO2 to CO increased by 1.5 to 2.1 times. The gold clusters were sufficiently small; therefore, there was no plasmonic resonant peak or heat generation. Because the near-field effect is based on a photochemical reaction, it can be applied to other metal complexes used in CO2 reduction, and it has other applications such as water splitting and water purification.

    DOI: 10.1117/1.JNP.14.046011

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  19. Mineralization induced by phosphorylated dry baker's yeast 査読有り

    Ojima, Y; Kihara, M; Yoshida, M; Igarashi, K; Yoshida, T; Azuma, M

    PLOS ONE   15 巻 ( 9 ) 頁: e0239774 - e0239774   2020年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PLoS ONE  

    We found the mineralization of Cu during long-term Cu2+ adsorption onto dry baker’s yeast cells phosphorylated using sodium cyclo-triphosphate. Field emission scanning electron microscopy (FESEM) with energy-dispersive X-ray spectroscopy confirmed that the elemental composition of minerals were copper, phosphorus, and oxygen. Synchrotron-based X-ray absorption fine structure showed that the local structure around Cu atoms deposited on the mineral was almost identical to that of commercial copper (II) phosphate Cu3(PO4)2 3H2O. However, the crystallinity was low, and the structure was slightly distorted. Time profile analysis using FESEM revealed that copper phosphate mineralization was first apparent on Day 3 of adsorption, whereas mineral formation plateaued at around Day 7. It seems that mineralization occurs by the local saturation of phosphate and Cu2+ on the yeast cells. Mineralization of the rare earth ion Dy3+ was also demonstrated during long-term adsorption. Mineralization on phosphorylated yeast cells appears to follow a common path for various types of metal ions and provides a promising technique for metal recovery via irreversible adsorption.

    DOI: 10.1371/journal.pone.0239774

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  20. Effects of the amount of Au nanoparticles on the visible light response of TiO<sub>2</sub> photocatalysts 査読有り

    Yoshida, T; Misu, Y; Yamamoto, M; Tanabe, T; Kumagai, J; Ogawa, S; Yagi, S

    CATALYSIS TODAY   352 巻   頁: 34 - 38   2020年8月

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    担当区分:筆頭著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Catalysis Today  

    We have succeeded to prepare Au nanopareticle deposited TiO2 photocatalysts (Au/TiO2) with control of Au nanoparticle size to be around 8 nm and variation of number density using a colloid photodepostion method. The prepared Au/TiO2 exhibits activity on decomposition (oxidation) of formic acid by thermally activated and photo-activated catalytic reactions. The thermally activated catalytic decomposition gradually increases with increasing the number density of deposited Au NPs and saturated, suggesting that the decomposition occurs on Au NPs surface and/or near the interface of TiO2 and Au NPs. On the other hand, the photocatalytic decomposition is significantly improved with rather small number density deposition of Au NPs and disappeared with high number density deposition. ESR measurements of Au/TiO2 in the surrounding similar to the photocatalytic decomposition suggests that electrons excited by plasmon resonance absorption in the Au NPs transfer to TiO2 to promote the decomposition. However, high number density deposition enhances electron capture by neighboring Au NPs and reduces the photocatalytic activity. Thus there should be the optimum number density of Au NPs on TiO2 for photocatalytic decomposition of formic acid.

    DOI: 10.1016/j.cattod.2019.12.035

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  21. Water-Splitting Activity of La-Doped NaTaO<sub>3</sub> Photocatalysts Sensitive to Spatial Distribution of Dopants 査読有り

    Sudrajat, H; Kitta, M; Ito, R; Nagai, S; Yoshida, T; Katoh, R; Ohtani, B; Ichikuni, N; Onishi, H

    JOURNAL OF PHYSICAL CHEMISTRY C   124 巻 ( 28 ) 頁: 15285 - 15294   2020年7月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Physical Chemistry C  

    Understanding the science behind highly active materials is essential for advancement in the field of photocatalytic water splitting for solar energy harvesting. Sodium tantalate (NaTaO3) doped with La cations is one of the best engineered materials for efficient water splitting to evolve hydrogen. In this study, physical insights into the sensitivity of the water-splitting activity to the spatial La distribution are discussed. The spatial distribution of La cations placed at the Na site was found to dictate the energy gradient of the conduction band bottom (CBB), resulting in a tunable electron population and hence water-splitting activity. A less homogeneous sample with a sufficiently large CBB gradient exhibited higher water-splitting activity. The mechanism of gradient tuning of the CBB through controlling the spatial dopant distribution is expected to be applicable to a broad range of metal oxide perovskites for artificial photosynthesis.

    DOI: 10.1021/acs.jpcc.0c03822

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  22. Thin film and noble metal loading effects on the photocatalytic reactivity of helium-plasma-induced nanostructured tungsten oxides 査読有り

    Feng, SY; Kajita, S; Yoshida, T; Ohno, N; Nagata, D; Tokitani, M

    MATERIALS RESEARCH EXPRESS   7 巻 ( 7 ) 頁: 075007 - 075007   2020年7月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Materials Research Express  

    Helium-plasma irradiation induces nanostructure formation on metal surfaces. This study investigated the photocatalytic performance of tungsten (W) oxide nanostructures formed on a thin film and the loading effects of noble metals. Methylene blue (MB) degradation was performed, and the performance of different nanostructured samples formed on thin-film and sheet W with changing the oxidization temperatures was compared; the differences were discussed in terms of the oxidation degree and vacancies. Moreover, noble metals (Pt, Ag, Au) were loaded onto the nanostructured sample oxide by magnetron sputtering as cocatalysts. The MB degradation ability was significantly enhanced by Pt loading. The results showed that nanostructuring and Pt support by using dry processes are novel routes for fabricating highly active photocatalysts.

    DOI: 10.1088/2053-1591/aba394

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    その他リンク: https://iopscience.iop.org/article/10.1088/2053-1591/aba394/pdf

  23. Photocatalytic Activity of Metal Oxide Supported Gallium Oxide for CO2 Reduction with Water

    Ito, R; Akatsuka, M; Ozawa, A; Yamamoto, M; Tanabe, T; Yoshida, T

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   93 巻 ( 5 ) 頁: 694 - 700   2020年5月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:公益社団法人 日本化学会  

    DOI: 10.1246/bcsj.20190366

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  24. Comparison of platinum photodeposition processes on two types of titanium dioxide photocatalysts 査読有り

    Yamamoto, M; Minoura, Y; Akatsuka, M; Ogawa, S; Yagi, S; Yamamoto, A; Yoshida, H; Yoshida, T

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   22 巻 ( 16 ) 頁: 8730 - 8738   2020年4月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Physical Chemistry Chemical Physics  

    The photodeposition method is useful for the preparation of metal-loaded photocatalysts, by which the metal precursors are adsorbed on the photocatalyst surface and reduced by photoexcited electrons to typically form metallic nanoparticles. In the present study, the photodeposition process of Pt nanoparticles was investigated on anatase and rutile TiO2photocatalysts. It was found that on the anatase surface, only some of the Pt4+precursors were first adsorbed in an adsorption equilibrium and reduced to form a smaller number of initial metal species; then, they functioned as electron receivers to reduce the remaining precursors on their metallic surfaces and become larger particles. In contrast, the rutile surface can adsorb most of the precursors and quickly reduce them upon photoirradiation to form nanoparticles, giving a larger number of small nanoparticles. As a result, the Pt-loaded rutile photocatalyst exhibited higher activity in hydrogen evolution from an aqueous methanol solution than the Pt-loaded anatase photocatalyst.

    DOI: 10.1039/c9cp06988g

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  25. Roles of Silver Co-catalyst on Gallium Oxide for Photocatalytic CO<sub>2</sub> Reduction to CO

    Yoshioka, K; Yamamoto, M; Tanabe, T; Yoshida, T

    E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY   18 巻 ( 0 ) 頁: 168 - 174   2020年4月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:公益社団法人 日本表面真空学会  

    It is well known that Ag loaded Gallium oxide (Ag/Ga2O3) promotes photocatalytic CO2reduction to CO. However, the role of the Ag co-catalyst in the CO2reduction has not been clarified. We have intended to find the relationship between the state of Ag loaded on Ga2O3and their activity for the photocatalytic CO2reduction. To achieve this, we have tried to control and stabilize the loading state of Ag on Ga2O3during their use for the photo-catalytic CO2reduction by adding methanol as a reducing agent. It is confirmed that methanol stabilizes the particle sizes of Ag nanoparticles (Ag-NPs) loaded on Ga2O3under the photocatalytic CO2reduction condition and is hardly decomposed to produce CO. Using Ga2O3loaded with size-controlled Ag-NPs as a photocatalyst for the CO2reduction, it is found that Ag-NPs with their sizes within 10-30 nm are active sites for the photocatalytic CO2reduction and the catalytic activity linearly increases with the increase of the number density of Ag-NPs. However, a higher Ag loading amount over 1.0 wt% promotes aggregation of Ag to be larger metal particles over 70 nm which are not active for the CO2reduction. (Figure Presented).

    DOI: 10.1380/ejssnt.2020.168

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  26. Black phosphorus synthesized by solvothermal reaction from red phosphorus and its catalytic activity for water splitting 査読有り

    Ozawa, A; Yamamoto, M; Tanabe, T; Hosokawa, S; Yoshida, T

    JOURNAL OF MATERIALS CHEMISTRY A   8 巻 ( 15 ) 頁: 7368 - 7376   2020年4月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Materials Chemistry A  

    We have succeeded in synthesizing black phosphorus (BP) by a one-pot solvothermal reaction of red phosphorus (RP) and ethylenediamine (ED) used as a solvent. To examine the reaction mechanism, we have investigated the influence of the synthesis conditions on BP, and the valence of dissolved phosphorus in the solvent after the reaction. P0 species and P3+ like species are very likely dissolved in ED as intermediates for BP production. Optimizing the reaction conditions, i.e., temperature, the charging amount of RP in ED and the particle size of RP, BP was synthesized with high yield. The synthesized BP has an extra peak at 10.2° in the X-ray diffraction pattern, which was assigned to stacking faults or periodic distortion in the direction of the c axis by simulation of diffraction. The synthesized BP with a Co-P cocatalyst showed high photocatalytic activity for hydrogen evolution from methanol aqueous solution under visible light irradiation.

    DOI: 10.1039/c9ta13441g

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  27. Utilization of La<sub>2</sub>O<sub>3</sub> as a Support of Ga<sub>2</sub>O<sub>3</sub> Photocatalyst to Enhance Activity on CO<sub>2</sub> Reduction with Water

    Ito, R; Akatsuka, M; Yamamoto, M; Tanabe, T; Yoshida, T

    E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY   18 巻 ( 0 ) 頁: 110 - 115   2020年3月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:公益社団法人 日本表面真空学会  

    We have prepared La2O3supported Ga2O3(Ga2O3/La2O3) photocatalyst to improve the photocatalytic activity of Ga2O3for CO2reduction with water under ultraviolet light irradiation without a noble metal cocatalyst. Significant improvement on both CO2reduction and water splitting was attained compared with those for non-supported Ga2O3and La2O3. The improve-ment is attributed to the transformation of the La2O3surface to NaLa(CO3)2 during the photocatalytic reduction tests in aqueous solution of NaHCO3. NaLa(CO3)2 was preferentially formed on the surface of La2O3without changing Ga2O3resulting in the structure of Ga2O3supported by NaLa(CO3)2. Once NaLa(CO3)2 fully covered the surface of La2O3, the high catalytic activity was kept long. (Figure Presented).

    DOI: 10.1380/ejssnt.2020.110

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  28. Preparation of Ga<sub>2</sub>O<sub>3</sub> photocatalyst highly active for CO<sub>2</sub> reduction with water without cocatalyst 査読有り

    Akatsuka, M; Kawaguchi, Y; Itoh, R; Ozawa, A; Yamamoto, M; Tanabe, T; Yoshida, T

    APPLIED CATALYSIS B-ENVIRONMENTAL   262 巻   頁: 118247 - 118247   2020年3月

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    担当区分:責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Applied Catalysis B: Environmental  

    Ga2O3 samples were synthesized by calcination of gallium nitrate powder at a given temperature ranging from 673 K to 1173 K (denoted as T-Ga2O3 with T, calcination temperature). XRD and XAFS structural analyses revealed that samples calcined at temperatures below 673 K were consisted of defective ε phase, whereas those calcined above 773 K of β and γ phases, and β phase dominated above 923 K. All calcined Ga2O3 samples promoted photocatalytic CO2 reduction with water to produce CO, H2 and O2. As for the H2 production by water splitting, the H2 production rates were well correlated with the surface areas of calcined Ga2O3 samples. It was also found that the water splitting and the CO2 reduction proceeded fully independently. 823-Ga2O3 showed the highest activity for the CO2 reduction, suggesting that the coexistence of β and γ phases plays a key role on the photocatalytic CO2 reduction.

    DOI: 10.1016/j.apcatb.2019.118247

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  29. Photocatalytic application of helium plasma induced nanostructured tungsten oxides 査読有り

    Feng, SY; Kajita, S; Tomita, Y; Yoshida, T; Ohno, N

    JAPANESE JOURNAL OF APPLIED PHYSICS   59 巻 ( SA ) 頁: SAAB04 - SAAB04   2020年1月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Japanese Journal of Applied Physics  

    In this study, two photosensitive nanostructured photocatalysts (i.e. a nanostructured W sheet (WNano) and a nanostructured W thin film (WNTF), respectively) were fabricated by helium plasma irradiation. In addition, the photocatalytic activity was examined for the degradation of methylene blue under visible light irradiation. The result revealed that the highest photocatalytic activity is observed for WNano subjected to calcination at 573 K. The difference in the photocatalytic activities between WNano and WNTF was possibly caused by the difference in the surface area and the presence of a W/WO3 interface. Among the series of the WNano photocatalysts subjected to calcination at different temperatures, the localized surface plasmon resonance of nanostructured W was likely responsible for photocatalysis.

    DOI: 10.7567/1347-4065/ab4601

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    その他リンク: http://iopscience.iop.org/article/10.7567/1347-4065/ab4601/pdf

  30. TiO<i><sub>x</sub></i>N<i><sub>y</sub></i>/TiO<sub>2</sub> Photocatalyst for Hydrogen Evolution under Visible Light Irradiation II Degradation of Photocatalytic Activity of TiO<i><sub>x</sub></i>N<i><sub>y</sub></i>/TiO<sub>2</sub> with Mild Oxidation 査読有り

    Ozawa, A; Yamamoto, M; Tanabe, T; Yoshida, T

    ACS OMEGA   4 巻 ( 24 ) 頁: 20430 - 20434   2019年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Omega  

    We have studied degradation of photocatalytic activity of TiOxNy for water splitting under visible light irradiation with heat treatment in O2/N2 mixed gas. The reduction of the N content by oxidation through the formation of O-N-O species (NOx) was confirmed as the result of the reduction of the catalytic activity. The catalytic activity is not simply related to the amount of N remained but that of N taking the chemical state of O-Ti-N in TiOxNy, which is the active species for visible light responsiveness on hydrogen evolution. N in TiOxNy is first oxidized to NO2 species during the oxidation, which reduces the activity. Then, O-N-O species (NOx) is removed as NOx gas from the surface. Because the formation of O-N-O in TiOxNy could induce an impurity energy level to enhance charge recombination, the loss of catalytic activity might be influenced by the formation of O-N-O species (NOx) rather than the loss of the N content from TiOxNy.

    DOI: 10.1021/acsomega.9b02979

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  31. TiO<i><sub>x</sub></i>N<i><sub>y</sub></i>/TiO<sub>2</sub> Photocatalyst for Hydrogen Evolution under Visible-Light Irradiation. I: Characterization of N in TiO<i><sub>x</sub></i>N<i><sub>y</sub></i>/TiO<sub>2</sub> Photocatalyst 査読有り

    Ozawa, A; Yamamoto, M; Tanabe, T; Yoshida, T

    ACS OMEGA   4 巻 ( 24 ) 頁: 20424 - 20429   2019年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Omega  

    TiOxNy/TiO2 was synthesized by nitriding of TiO2 in NH3 gas. TiOxNy/TiO2 generated hydrogen from methanol aqueous solution under visible-light irradiation. It was revealed by N K-edge XANES and N 1s XPS measurements that the N species contributing to visible-light responsiveness was the O-Ti-N species. The structure of TiOxNy/TiO2 showing the photocatalytic activity was a double shell type with thin layers of TiOxNy that covers the TiO2 core. Although N content on the surface decreased during the photocatalytic reaction, N was supplied from the deeper side to keep the TiOxNy phase at the surface and the activity as well.

    DOI: 10.1021/acsomega.9b02977

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  32. A Nickel-Diamine/Mesoporous Silica Composite as a Heterogeneous Chiral Catalyst for Asymmetric 1,4-Addition Reactions 査読有り

    Ishitani, H; Kanai, K; Yoo, WJ; Yoshida, T; Kobayashi, S

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   58 巻 ( 38 ) 頁: 13313 - 13317   2019年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Angewandte Chemie - International Edition  

    A chiral composite material, derived from the deposition of a chiral nickel–diamine complex via wet impregnation to MCM-41, was shown to be an efficient heterogeneous catalyst for asymmetric 1,4-addition reactions of 1,3-dicarbonyl compounds with nitroalkenes, and of nitromethane with alkylidenemalonates. It was discovered that MCM-41 enhanced the reactivity and improved the stability of the chiral nickel complex that resides within the mesoporous material.

    DOI: 10.1002/anie.201906349

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    その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/anie.201906349

  33. Realization of red shift of absorption spectra using optical near-field effect 査読有り

    Yatsui, T; Nakahira, Y; Nakamura, Y; Morimoto, T; Kato, Y; Yamamoto, M; Yoshida, T; Iida, K; Nobusada, K

    NANOTECHNOLOGY   30 巻 ( 34 ) 頁: 34LT02 - 34LT02   2019年8月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Nanotechnology  

    In many applications such as CO2 reduction and water splitting, high-energy photons in the ultraviolet region are required to complete the chemical reactions. However, to realize sustainable development, the photon energies utilized must be lower than the absorption edge of the materials including the metal complex for CO2 reduction, the electrodes for water splitting, because of the huge amount of lower energy than the visible region received from the sun. In the previous works, we had demonstrated that optical near-fields (ONFs) could realize chemical reactions, by utilizing photon energies much lower than the absorption edge because of the spatial non-uniformity of the electric field. In this paper, we demonstrate that an ONF can realize the red shift of the absorption spectra of the metal-complex material for photocatalytic reduction. By attaching the metal complex to ZnO nano-crystalline aggregates with nano-scale protrusions, the absorption spectra by using diffuse reflection of the metal complex can be shifted to a longer wavelength by 10.6 nm. The results of computational studies based on a first-principles computational program including the ONF effect provide proof of the increase in the absorption of the metal complex at lower photon energies. Since the near-field assisted field increase improves the carrier excitation in the metal-complex materials, this effect may be universal and it could applicable to CO2 reduction using the other metal-complex materials, as well as to the other photo excitation process including water splitting.

    DOI: 10.1088/1361-6528/ab2092

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    その他リンク: http://iopscience.iop.org/article/10.1088/1361-6528/ab2092/pdf

  34. Air-stable and reusable cobalt ion-doped titanium oxide catalyst for alkene hydrosilylation 査読有り

    Mitsudome, T; Fujita, S; Sheng, M; Yamasaki, J; Kobayashi, K; Yoshida, T; Maeno, Z; Mizugaki, T; Jitsukawa, K; Kaneda, K

    GREEN CHEMISTRY   21 巻 ( 16 ) 頁: 4566 - 4570   2019年8月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Green Chemistry  

    Alkene hydrosilylation is important for the synthesis of organosilicon compounds, for which precious metal complexes have been used as industrial catalysts. Considering environmental and economic concerns, the development of earth-abundant metal catalysts with high stability, easy separability, and high reusability is strongly desired. Herein, we report that a new cobalt ion-doped titanium dioxide (Co/TiO2) catalyst was synthesized by hydrogen treatment method. The Co/TiO2 catalyst acts as a highly efficient heterogeneous catalyst for the anti-Markovnikov hydrosilylation of alkenes under solvent-free conditions. Various alkenes were selectively converted to the corresponding alkylsilanes. This catalyst showed high stability in air and high reusability with maintained activity. The investigation of the relationship between the active site structure and catalytic performance of Co/TiO2 disclosed that the high stability and durability of Co/TiO2 are originated from the strong interaction between Co and TiO2 through the formation of CoTiO3 solid solution species.

    DOI: 10.1039/c9gc01981b

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  35. Preparation of visible-light-responsive photocatalyst by dehydronitrization of gallium oxide hydroxide for hydrogen evolution from water 査読有り

    Kato, Y; Yamamoto, M; Ozawa, A; Tanabe, T; Yoshida, T

    APPLIED CATALYSIS B-ENVIRONMENTAL   250 巻   頁: 112 - 116   2019年8月

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    担当区分:責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Applied Catalysis B: Environmental  

    We have performed dehydronitrization of GaOOH under NH3 flow to produce nitrogen doped Ga2O3 and examined their photocatalytic activities for H2 evolution from an aqueous methanol solution under visible light irradiation. GaOOH was synthesized by hydrothermal treatment and dehydronitrided at a temperature ranging from 773 K to 1273 K under NH3 flow. At first, GaOOH was dehydrided to Ga2O3 under 873 K and followed nitrization. With increasing dehydronitrization temperature, the products were getting closer to full nitride (GaN). Among all dehydronitrided samples, only one sample sintered at 1173 K showed photocatalytic activity under visible light irradiation and its crystalline structure had not changed before and after the reactions, while other samples did not show the activity and were oxidized to GaOOH. From thermodynamical aspect, if nitrogen dissolved into oxide or making oxynitride, its chemical potential must be lower than that of N in GaN. Therefore, there should be some gallium oxinitride phase like GaNyO3-x stable in water showing photocatalytic activity.

    DOI: 10.1016/j.apcatb.2019.03.009

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  36. Electron Population and Water Splitting Activity Controlled by Strontiunn Cations Doped in KTaO<sub>3</sub> Photocatalysts 査読有り

    Sudrajat, H; Dhakal, D; Kitta, M; Sasaki, T; Ozawa, A; Babel, S; Yoshida, T; Ichikuni, N; Onishi, H

    JOURNAL OF PHYSICAL CHEMISTRY C   123 巻 ( 30 ) 頁: 18387 - 18397   2019年8月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Physical Chemistry C  

    KTaO3 was doped with Sr cations, and its photocatalytic activity for the overall water splitting was investigated. By doping with Sr, a Sr-rich shell was formed over a Sr-poor core. Extended X-ray absorption fine structure spectroscopy revealed the simultaneous occupation of the K sites and Ta sites by Sr cations. A concentration gradient of Sr cations occupying the Ta sites was suggested to be produced after doping with Sr. The concentration gradient of Sr cations simultaneously induced an energy gradient of the conduction band edge bottom. Hence, photoexcited electrons are separated, which are driven away to the bulk by the energy gradient, from the complementary holes present on the surface. The higher the Sr cation concentration, the higher the energy gradient produced. Thus, the electron-hole separation is improved and the electron population accordingly increases with the increase in the Sr cation concentration. Nevertheless, the increase in the Sr cation concentration led to the decrease in the water splitting activity. The highest water splitting activity was observed for bare KTaO3. The decreased water splitting activity was proposed to be primarily due to the blockage of the electron transfer to the cocatalysts by the Sr-rich shell and the poor O2 evolution ability of the Sr-rich shell.

    DOI: 10.1021/acs.jpcc.9b03640

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  37. Selective Hydrogen Production from Formate Using Nanoparticle with Homogeneously Polymer-dispersed Platinum Clusters 査読有り

    Minami, Y; Muroga, Y; Yoshida, T; Amao, Y

    CHEMISTRY LETTERS   48 巻 ( 8 ) 頁: 775 - 778   2019年8月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Chemistry Letters  

    Selective hydrogen production from formic acid with platinum nano-cluster dispersed by various protective polymer based agents polyvinylpyrrolidone (Pt-PVP) or polyacrylic acid (Pt-PAA) is attempted. The ratio of hydrogen to CO2 was estimated to be c.a. 1.0 (stoichiometric ratio) under the argon-saturated buffer solution containing formic acid with Pt-PVP.

    DOI: 10.1246/cl.190311

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  38. Photocatalytic decomposition of ethylene using He plasma induced nano-TiO<sub>2</sub> 査読有り

    Shin Kajita, Yudai Tomita, Eriko Yasunaga, Tomoko Yoshida, Kazuya Miyaguchi, Hirohiko Tanaka, Noriyasu Ohno

    Japanese Journal of Applied Physics   58 巻 ( 7 ) 頁: 070903 - 070903   2019年6月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP Publishing  

    DOI: 10.7567/1347-4065/ab2830

    その他リンク: http://iopscience.iop.org/article/10.7567/1347-4065/ab2830/pdf

  39. Fabrication of a nanostructured TiO<sub>2</sub> photocatalyst using He plasma-irradiated tungsten and ethylene gas decomposition 査読有り

    Yudai Tomita, Shin Kajita, Eriko Yasunaga, Tomoko Yoshida, Noriyasu Ohno, Hirohiko Tanaka

    Japanese Journal of Applied Physics   58 巻 ( SE ) 頁: SEEG01 - SEEG01   2019年5月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP Publishing  

    DOI: 10.7567/1347-4065/ab09c8

    その他リンク: https://iopscience.iop.org/article/10.7567/1347-4065/ab09c8

  40. Chemical forms of molybdenum ion in nitric acid solution studied using liquid-phase X-ray absorption fine structure, Ultraviolet-Visible absorption spectroscopy and first-principles calculations 査読有り

    Watanabe, S; Sato, T; Nakaya, M; Yoshida, T; Onoe, J

    CHEMICAL PHYSICS LETTERS   723 巻   頁: 76 - 81   2019年5月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Chemical Physics Letters  

    We have investigated chemical forms of molybdenum ion in nitric acid solution, using liquid-phase X-ray absorption fine structure, ultraviolet–visible absorption spectroscopy and first-principles calculations, from a viewpoint of disposal of high-level radioactive nuclear liquid wastes. The experimental and theoretical results indicated that Mo is a hexavalent ion and forms a hexa-coordination binuclear-structured complex in the 2 M nitic acid solution. The predominant chemical species of Mo complexes in the 2 M nitric acid solution (which is used for HLLW) are assigned to be [Mo2O5(H2O)6]2+ and [Mo2O4(OH)(H2O)6]3+. These species may play a crucial role of forming so-called yellow-phase in vitrified objects.

    DOI: 10.1016/j.cplett.2019.02.049

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  41. Photocatalytic Activity of Ga<sub>2</sub>O<sub>3</sub> Supported on Al<sub>2</sub>O<sub>3</sub> for Water Splitting and CO<sub>2</sub> Reduction 査読有り

    Ito, R; Akatsuka, M; Ozawa, A; Kato, Y; Kawaguchi, Y; Yamamoto, M; Tanabe, T; Yoshida, T

    ACS OMEGA   4 巻 ( 3 ) 頁: 5451 - 5458   2019年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Omega  

    We have examined the photocatalytic activity of Ga 2 O 3 supported on Al 2 O 3 (Ga 2 O 3 /Al 2 O 3 catalyst) without a noble metal cocatalyst for water splitting and reduction of CO 2 with water under UV light irradiation by changing the loading amount of Ga 2 O 3 . All prepared Ga 2 O 3 /Al 2 O 3 catalysts show photocatalytic activities for both water splitting and CO 2 reduction, and their activities are significantly improved compared to those of nonsupported Ga 2 O 3 and Al 2 O 3 . The water splitting is dominated for Ga 2 O 3 /Al 2 O 3 with less than 1.0 vol % of Ga 2 O 3 loaded, whereas the CO 2 reduction, for higher Ga 2 O 3 -loaded samples (2.6, 4.2 vol %). Crystalline structure characterizations of Ga 2 O 3 /Al 2 O 3 catalysts indicate that active sites for both reactions are different. The water splitting proceeds on nanometer-sized Ga 2 O 3 rods dispersed on an Al 2 O 3 support consisting of a little distorted α-Ga 2 O 3 phase. On the other hand, the CO 2 reduction proceeds on sub-micrometer-sized Ga 2 O 3 particles consisting of mixed phases of α-Ga 2 O 3 and γ-Ga 2 O 3 or with appearance of boundaries between the α and γ phases, which plays a critical role. Al 2 O 3 used as the support of the Ga 2 O 3 particles does not seem to play an important role in the photocatalytic CO 2 reduction.

    DOI: 10.1021/acsomega.9b00048

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  42. Quantitative XAFS/EELS analyses of nitrogen species in titanium oxide photocatalysts 査読有り

    Yoshida, T; Yamamoto, M; Akatsuka, M; Ozawa, A; Kato, Y; Yagi, S; Tanabe, T

    SURFACE AND INTERFACE ANALYSIS   51 巻 ( 1 ) 頁: 46 - 50   2019年1月

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    担当区分:筆頭著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Surface and Interface Analysis  

    With a view to rational designing of a highly functional visible-light TiO2 photocatalyst, nitrogen atoms were doped into TiO2 samples by an ion implantation technique which enables to control the depth and concentration of dopants. Although the absorbance in the visible-light region of the sample increased by the nitrogen doping, photocatalytic activity of the sample was not directly connected with the photo-absorbance. The N K-edge X-ray absorption near edge structure (XANES) spectrum of the photocatalytic active sample (A-cat) showed a characteristic double peak at 398 and 401 eV, and the XANES spectrum of the inactive sample (I-cat) a distinct single peak around 401 eV. These features of the XANES spectra were well reproduced by theoretical simulations based on the model where an O atom in TiO2 was replaced by N ((N)s) for A-cat, and that of quasi NO2 molecule ((NO2)s) for I-cat. Therefore, we have concluded that the nitrogen atom occupying the oxygen site of TiO2 is photocatalytic active species effective for visible light photocatalysis. In addition, the quantitative XANES/ELNES analysis has revealed that the photo-absorbance ratio of I-cat to A-cat corresponds well to the ratio of total doped nitrogen concentration rather than photocatalytic active nitrogen ((N)s) concentration. This result indicates that not only (N)s but also (NO2)s also absorb the visible light. Thus, the absorbance in the visible-light region is not necessarily an indication of the visible-light response of a photocatalyst.

    DOI: 10.1002/sia.6543

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  43. Effects of the crystalline structure of Ga<sub>2</sub>O<sub>3</sub> on the photocatalytic activity for CO production from CO<sub>2</sub> 査読有り

    Kawaguchi, Y; Yamamoto, M; Ozawa, A; Kato, Y; Yoshida, T

    SURFACE AND INTERFACE ANALYSIS   51 巻 ( 1 ) 頁: 79 - 84   2019年1月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Surface and Interface Analysis  

    Ga2O3 samples with different crystalline structures were prepared by calcination of a gallium nitrate powder around 800 K. Ga2O3 samples with mixed phases of γ and β showed high photocatalytic activity for CO production from CO2 reduction with water, and the activity was even higher than that for an Ag-loaded β-Ga2O3. The photocatalytic activity increased with time. The increase was attributed to the appearance of GaOOH resulting from the interaction of Ga2O3 with water during the reaction as revealed by XRD and XPS analyses. In situ FT-IR measurements revealed that bicarbonates and bidentate carbonate species were adsorbed on GaOOH. Therefore, the increase of the photocatalytic activity with time would be derived from the formation of GaOOH phase on the γ-Ga2O3 and β-Ga2O3 sample.

    DOI: 10.1002/sia.6552

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  44. Control of nitrogen doping in NaTaO<sub>3</sub> synthesized by hydrothermal reaction and chemical state of nitrogen 査読有り

    Ozawa, A; Kobayashi, K; Yoshida, T

    SURFACE AND INTERFACE ANALYSIS   51 巻 ( 1 ) 頁: 89 - 94   2019年1月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Surface and Interface Analysis  

    Nitrogen-doped NaTaO3 was synthesized through 1-pot reaction, hydrothermal process using Ta3N5 as precursor. Changing concentration and amount of NaOH aqueous solution influenced nitrogen content in NaTaO3. Absorption edge of nitrogen-doped NaTaO3 was extended at 570 nm, and absorbance in visible light region depended on nitrogen content in NaTaO3. Anodic photocurrent measured under visible light irradiation became larger with increasing nitrogen content in NaTaO3-xNy. Under ultraviolet light irradiation (λ ≤ 400 nm), the highest anodic photocurrent was observed when nitrogen concentration was y = 0.024. It was possible to expand the wavelength range that can be effectively utilized for the photoelectrochemical reaction.

    DOI: 10.1002/sia.6556

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  45. Study on carbon dioxide reduction with water over metal oxide photocatalysts 査読有り

    Kato, Y; Yamamoto, M; Akatsuka, M; Ito, R; Ozawa, A; Kawaguchi, Y; Tanabe, T; Yoshida, T

    SURFACE AND INTERFACE ANALYSIS   51 巻 ( 1 ) 頁: 40 - 45   2019年1月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Surface and Interface Analysis  

    Various metal oxides with 0.1 wt% Ag loaded as a cocatalyst were prepared by an impregnation method and examined their photocatalytic activity for CO2 reduction with water. Among all the prepared Ag-loaded metal oxides, Ga2O3, ZrO2, Y2O3, MgO, and La2O3 showed activities for CO and H2 productions under ultraviolet light irradiation. Thus, metal oxides involving metal cations with closed shell electronic structures such as d0, d10, and s0 had the potential for CO2 reduction with water. In situ Fourier transform infrared measurement revealed that the photocatalytic activity and selectivity for CO production are controlled by the amount and chemical states of CO2 adsorbed on the catalyst surface and by the surface basicity, as summarized as follows: Ag/ZrO2 enhanced H2 production rather than CO production due to very little CO2 adsorption. Ag/Ga2O3 exhibited the highest activity for CO production, because adsorbed monodentate bicarbonate was effectively converted to bidentate formate being the reaction intermediates for CO production owing to its weak surface basicity. Ag/La2O3, Ag/Y2O3, and Ag/MgO having both weak and strong basic sites adsorbed larger amount of carbonate species including their ions and suppressed H2 production. However, the adsorbed carbonate species were hardly converted to the bidentate formate.

    DOI: 10.1002/sia.6542

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  46. One-Step Plasma Synthesis of Nb<sub>2</sub>O<sub>5</sub> Nanofibers and their Enhanced Photocatalytic activity 査読有り

    Kajita, S; Mimuro, F; Yoshida, T; Ohno, N; Yoshida, N

    CHEMPHYSCHEM   19 巻 ( 23 ) 頁: 3237 - 3246   2018年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ChemPhysChem  

    Fiberform nanostructured niobium (Nb) was fabricated by one step helium (He) plasma irradiation. He ion implantation formed He nano-bubbles on a Nb plate and led to formation of protrusions while migrating in Nb matrix; fiberform nanostructures (FN) were grown when the fluence became high (>1026 m−2). The necessary conditions for the formation of Nb FN were revealed to be the surface temperature range of 900–1100 K and the incident ion energy higher than 70 eV. The sample was oxidized at 573–773 K in an air atmosphere, and Pt nanoparticles were photo-deposited on the Nb2O5 samples. The surface was analyzed by scanning electron microscope, transmission electron microscope, x-ray photoelectron spectroscopy, and ultraviolet-visible spectrophotometry. Photocatalytic activity of the fabricated materials was studied using methylene blue (MB) decolorization process. An enhanced photocatalytic performance was identified on FN Nb2O5 substrate with Pt deposition.

    DOI: 10.1002/cphc.201800769

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  47. Analysis of optical properties and structures of nitrogen doped gallium oxide<sup>∗</sup>

    Kato Y., Yamamoto M., Ozawa A., Kawaguchi Y., Miyoshi A., Oshima T., Maeda K., Yoshida T.

    e-Journal of Surface Science and Nanotechnology   16 巻 ( 0 ) 頁: 262 - 266   2018年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:公益社団法人 日本表面真空学会  

    To promote photocatalytic activity of gallium oxides (Ga2O3) on CO2 reduction with water under visible light irradiation, we have tried nitrogen doping into Ga2O3 with different crystalline structures. In diffuse reflectance UV-vis spectra, absorption bands appeared in the visible light region after the nitrogen doping and the absorption edge shifted to a longer wavelength region with increasing nitrogen doping temperature. N K-edge XANES analysis clearly showed two kinds of nitrogen species doped in the samples; gallium nitride (GaN) species and molecular like nitrogen. In XRD patterns, nitrogen doping at temperatures above 823 K, gallium nitride phases appeared while the original crystal structures of gallium oxide samples maintained when nitrogen doping temperature was less than 823 K. However, photocatalytic CO2 reduction under visible light irradiation was insignificant for all the nitrogen doped samples, because nitrogen doped in Ga2O3 samples was unstable in water under the visible light

    DOI: 10.1380/ejssnt.2018.262

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  48. Fabrication of photocatalytically active vanadium oxide nanostructures via plasma route 査読有り

    Kajita, S; Yoshida, T; Ohno, N; Ichino, Y; Yoshida, N

    JOURNAL OF PHYSICS D-APPLIED PHYSICS   51 巻 ( 21 ) 頁: 215201 - 215201   2018年5月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Physics D: Applied Physics  

    Plasma irradiation was used to create nanostructured vanadium oxide with potential commercial and industrial applications. Morphology changes were induced at the nano- and micro-meter scale, accompanied by the growth of helium nanobubbles. Micrometer-sized pillars, cube-shaped nanostructures, and fuzzy fiberform nanostructures were grown on the surface; the necessary conditions in terms of the incident ion energy and the surface temperature for those morphology changes were revealed. Hydrogen production experiments using a photocatalytic reaction with aqueous methanol solution were conducted on the fabricated samples. Enhanced H2 production was confirmed with the plasma irradiated nanostructured sample that had been oxidized in air atmosphere. Photocatalytically inactive vanadium oxide exhibited a high photocatalytic activity after nanostructurization of the surface by helium plasma irradiation.

    DOI: 10.1088/1361-6463/aabe44

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    その他リンク: http://iopscience.iop.org/article/10.1088/1361-6463/aabe44/pdf

  49. Direct cross-coupling between atkenes and tetrahydrofuran with a platinum-loaded titanium oxide photocatalyst 査読有り

    Tyagi, A; Yamamoto, A; Yamamoto, M; Yoshida, T; Yoshida, H

    CATALYSIS SCIENCE & TECHNOLOGY   8 巻 ( 10 ) 頁: 2546 - 2556   2018年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Catalysis Science and Technology  

    A Pt-loaded TiO2 photocatalyst successfully catalyzed the direct cross-coupling between various alkenes and tetrahydrofuran (THF) without any additional oxidizing agent. The reaction between cyclohexene and THF gave three cross-coupling products, namely, 2-cyclohexyltetrahydrofuran (A), 2-(cyclohex-2-en-1-yl)tetrahydrofuran (B) and 2-(cyclohex-1-en-1-yl)tetrahydrofuran (C), along with gaseous hydrogen. The mechanistic study revealed that these products were formed through different individual mechanisms: successive addition of two radical species, a 2-tetrahydrofuranyl radical and a hydrogen radical, to the double bond of cyclohexene for A, coupling of a 3-cyclohexenyl radical and a 2-tetrahydrofuranyl radical for B, and 2-tetrahydrofuranyl radical addition and hydrogen radical elimination at the double bond of cyclohexene for C. Among these three mechanisms, those for B and C are dehydrogenative. In this photocatalytic reaction system, since the cyclohexene molecule has enough reactivity, due to the localized π electron density, the Pt nanoparticles loaded on the TiO2 function not as a metal catalyst but as an electron receiver to enhance the charge separation, although the dehydrogenative cross-coupling of benzene with THF requires Pd metal catalysis.

    DOI: 10.1039/c8cy00129d

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  50. Preparation of gallium oxide photocatalysts and their silver loading effects on the carbon dioxide reduction with water 査読有り

    Kawaguchi, Y; Akatsuka, M; Yamamoto, M; Yoshioka, K; Ozawa, A; Kato, Y; Yoshida, T

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY   358 巻   頁: 459 - 464   2018年5月

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    担当区分:責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Photochemistry and Photobiology A: Chemistry  

    Ga2O3 prepared by calcination of a gallium nitrate powder showed high activity for CO2 reduction with water to produce CO, and the CO production rate was 150 times that of commercially available Ga2O3 (CA-Ga2O3). Although we also prepared Ag loaded Ga2O3 (Ag/Ga2O3) for further improvement of CO production, the CO production activity decreased by Ag loading on the prepared Ga2O3. On the other hand, CO production was enhanced by Ag loading on CA-Ga2O3. The crystalline structures of the prepared Ga2O3 and CA-Ga2O3 were coexistence of γ- and β- phases of Ga2O3 and single β-phase of Ga2O3, respectively. The crystalline structure of CA-Ga2O3 was maintained after Ag loading with various methods, however, that of the prepared Ga2O3 changed by Ag loading. Therefore, the CO production activity increased by Ag loading depended on the crystalline structure of Ga2O3 supports. In addition, we revealed that Ga2O3 with mixed phases of γ- and β- not loaded with Ag exhibited the highest photocatalytic activity for CO production.

    DOI: 10.1016/j.jphotochem.2017.11.010

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  51. Sodium hexatitanate photocatalysts prepared by a flux method for reduction of carbon dioxide with water 査読有り

    Yoshida, H; Sato, M; Fukuo, N; Zhang, LK; Yoshida, T; Yamamoto, Y; Morikawa, T; Kajino, T; Sakano, M; Sekito, T; Matsumoto, S; Hirata, H

    CATALYSIS TODAY   303 巻   頁: 296 - 304   2018年4月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Catalysis Today  

    Flux method was applied to prepare sodium hexatitanate (Na2Ti6O13) photocatalysts for reduction of carbon dioxide with water. The preparation conditions were examined, such as the starting material, the flux, the composition in the molten mixture, the holding temperature, and the cooling rate of the molten mixture, so as to obtain several sodium hexatitanate samples consisting of the crystals with various morphologies and sizes. These samples were loaded with 0.1 wt% of Ag cocatalyst nanoparticles (Ag/Na2Ti6O13) and examined for photocatalytic reduction of carbon dioxide with water, where carbon monoxide, hydrogen and oxygen were formed as products. It was found that the photocatalytic production rate of carbon monoxide varied with the morphology and the size of the sodium hexatitanate crystals. Among the prepared samples, thick rod-like crystals exhibited high photocatalytic activity for the reduction of carbon dioxide.

    DOI: 10.1016/j.cattod.2017.09.029

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  52. Effect of Ag co-catalyst on CO<sub>2</sub> adsorption states over Ga<sub>2</sub>O<sub>3</sub> photocatalyst 査読有り

    Yamamoto, M; Yagi, S; Yoshida, T

    CATALYSIS TODAY   303 巻   頁: 334 - 340   2018年4月

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    担当区分:責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Catalysis Today  

    Ag species in the Ag loaded Ga2O3 (Ag/Ga2O3) photocatalysts were investigated with regard to changes in their structures and the chemical states before and after the photocatalytic CO2 reduction with water. Ag clusters with the size of around one nanometer in as prepared 0.1 wt% Ag/Ga2O3 sample became larger metallic Ag nanoparticles with the size of several nanometers after the reaction. In the 1.0 wt% Ag/Ga2O3 sample, Ag nanoparticles having the AgGaO2 interface structure decomposed to aggregated Ag metal particles after the reaction. Such transition in the morphology and chemical states of Ag species could explain the variations in photocatalytic activities of these samples during the reaction, and suggested that at least metallic Ag particles would function as effective co-catalysts. In-situ FT-IR measurements of the Ag/Ga2O3 samples before and after the reaction, we could not detect CO2 molecules adsorbing on metallic Ag nanoparticles in dark. Under light irradiation, however, the absorption bands originated from the photo-adsorbed CO2 species on Ag metal nanoparticles appeared. Thus, we detected the interaction of CO2 molecules and metallic Ag nanoparticles as the effective co-catalysts for CO2 reduction.

    DOI: 10.1016/j.cattod.2017.09.025

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  53. Synthesis of Ag nanoparticles prepared by a solution plasma method and application as a cocatalyst for photocatalytic reduction of carbon dioxide with water 査読有り

    Yoshida, T; Yamamoto, N; Mizutani, T; Yamamoto, M; Ogawa, S; Yagi, S; Nameki, H; Yoshida, H

    CATALYSIS TODAY   303 巻   頁: 320 - 326   2018年4月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Catalysis Today  

    Silver nanoparticles (Ag NPs) were synthesized by a solution plasma method (SPM) in an aqueous solution of ammonia. Optical emission spectra of the plasma revealed that Ag NPs are fabricated with the sputtering of Ag rods as electrode by the produced energetic plasma particles such as H, OH and O radicals. In-situ optical absorption measurements of the solution during the discharge directly presented the concerted formation and aggregation processes of the Ag NPs, which controlled the size of Ag NPs. The synthesized Ag NPs were loaded on gallium oxide (Ga2O3) photocatalyst, and the photocatalytic activities of the obtained Ag loaded Ga2O3 (Ag/Ga2O3) samples were evaluated. Although the photocatalytic reaction proceeded over all the samples to produce CO, the CO production rates decreased with the reaction time. Measurements of DR UV–vis spectra and TEM images revealed that a part of the Ag NPs migrated and aggregated on the photocatalyst surface to become larger particles during the photocatalytic reaction, which would be related to the decrease of the photocatalytic activity. It was also found that the photoirradiation treatment on the prepared Ag/Ga2O3 sample before the use for the photocatalytic reaction improves the photocatalytic performance.

    DOI: 10.1016/j.cattod.2017.08.047

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  54. Spectroscopic and first-principles calculation studies of the chemical forms of palladium ion in nitric acid solution for development of disposal of high-level radioactive nuclear wastes 査読有り

    Watanabe, S; Sato, T; Yoshida, T; Nakaya, M; Yoshino, M; Nagasaki, T; Inaba, Y; Takeshita, K; Onoe, J

    AIP ADVANCES   8 巻 ( 4 )   2018年4月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:AIP Advances  

    We have investigated the chemical forms of palladium (Pd) ion in nitric acid solution, using XAFS/UV-vis spectroscopic and first-principles methods in order to develop the disposal of high-level radioactive nuclear liquid wastes (HLLW: radioactive metal ions in 2 M nitric acid solution). The results of theoretical calculations and XAFS/UV-vis spectroscopy indicate that Pd is a divalent ion and forms a square-planar complex structure coordinated with four nitrate ions, [Pd(NO3)4]2-, in nitric acid solution. This complex structure is also thermodynamically predicted to be most stable among complexes [Pd(H2O)x(NO3)4-x]x-2 (x = 0-4). Since the overall feature of UV-vis spectra of the Pd complex was independent of nitric acid concentration in the range 1-6 M, the structure of the Pd complex remains unchanged in this range. Furthermore, we examined the influence of γ-ray radiation on the [Pd(NO3)4]2- complex, using UV-vis spectroscopy, and found that UV-vis spectra seemed not to be changed even after 1.0 MGy irradiation. This implies that the Pd complex structure will be still stable in actual HLLW. These findings obtained above are useful information to develop the vitrification processes for disposal of HLLW.

    DOI: 10.1063/1.5025778

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  55. Fuzzy nanostructure growth on precious metals by He plasma irradiation 査読有り

    Shin Kajita, Tomohiro Nojima, Yudai Tomita, Noriyasu Ohno, Hirohiko Tanaka, Naoaki Yoshida, Miyuki Yajima, Tsuyoshi Akiyama, Masayuki Tokitani, Takashi Yagi

    Surface and Coatings Technology   340 巻   頁: 86 - 92   2018年4月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    DOI: 10.1016/j.surfcoat.2018.02.026

  56. Robust Binding between Carbon Nitride Nanosheets and a Binuclear Ruthenium(II) Complex Enabling Durable, Selective CO<sub>2</sub> Reduction under Visible Light in Aqueous Solution 査読有り

    Kuriki, R; Yamamoto, M; Higuchi, K; Yamamoto, Y; Akatsuka, M; Lu, D; Yagi, S; Yoshida, T; Ishitani, O; Maeda, K

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   56 巻 ( 17 ) 頁: 4867 - 4871   2017年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Angewandte Chemie - International Edition  

    Carbon nitride nanosheets (NS-C3N4) were found to undergo robust binding with a binuclear ruthenium(II) complex (RuRu′) even in basic aqueous solution. A hybrid material consisting of NS-C3N4 (further modified with nanoparticulate Ag) and RuRu′ promoted the photocatalytic reduction of CO2 to formate in aqueous media, in conjunction with high selectivity (approximately 98 %) and a good turnover number (>2000 with respect to the loaded Ru complex). These represent the highest values yet reported for a powder-based photocatalytic system during CO2 reduction under visible light in an aqueous environment. We also assessed the desorption of RuRu′ from the Ag/C3N4 surface, a factor that can contribute to a loss of activity. It was determined that desorption is not induced by salt additives, pH changes, or photoirradiation, which partly explains the high photocatalytic performance of this material.

    DOI: 10.1002/anie.201701627

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    その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/anie.201701627

  57. Enhancement of photocatalytic activity of TiO<sub>2</sub> by plasma irradiation 査読有り

    Kajita, S; Yoshida, T; Ohno, N; Ishida, T; Kitaoka, D

    JAPANESE JOURNAL OF APPLIED PHYSICS   55 巻 ( 10 ) 頁: 106202 - 106202   2016年10月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Japanese Journal of Applied Physics  

    In this study, plasma irradiations to titanium were conducted to enhance the photocatalytic activity of titanium oxide. When titanium is exposed to He plasmas, various morphology changes occur as forming nano-bubbles near the surface. Photocatalytic activity of the oxidized helium plasma irradiated titanium samples with nano-cones and microstructures were assessed by the hydrogen production from aqueous methanol solution. It is shown that the He plasma irradiation increases the photocatalytic activity more than double. Moreover, nitrogen mixture plasma irradiation to titanium (oxide) was conducted for doping nitrogen, which has been regarded as method to create visible light reactivity. It is shown from X-ray photoelectron spectroscopy (XPS) analysis that nitrogen doping has been successfully conducted under specific conditions.

    DOI: 10.7567/JJAP.55.106202

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    その他リンク: http://stacks.iop.org/1347-4065/55/i=10/a=106202?key=crossref.69ed7b7971d62ec6f8c9129ecd2a2c59

  58. Fuzzy nanostructure growth on Ta/Fe by He plasma irradiation

    Kajita, S; Ishida, T; Ohno, N; Hwangbo, D; Yoshida, T

    SCIENTIFIC REPORTS   6 巻   頁: 30380   2016年7月

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    記述言語:英語   出版者・発行元:Scientific Reports  

    In this study, we show from helium (He) plasma irradiation to tantalum and iron surfaces that morphology changes in nanoscale occur on the both metals. In particular, from systematic irradiation experiments, it is identified that fuzzy nanostructures are grown on the both metals. The necessary conditions for the morphology changes are discussed based on the experimental results in terms of the helium migration, the physical sputtering, and the shear modulus of materials. Because oxides or oxinitrides of iron and tantalum are thought of as visible light responsive photocatalytic materials, the present work shows wide potential of usage of plasmas as a tool to tailor photocatalytic materials.

    DOI: 10.1038/srep30380

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  59. Ag K- and L3-edge XAFS study on Ag species in Ag/Ga2O3photocatalysts 査読有り

    M. Yamamoto , T. Yoshida , N. Yamamoto , T. Nomoto , A. Yamamoto , H. Yoshida , S. Yagi

    Journal of Physics: Conference Series   712 巻   頁: 012074   2016年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1088/1742-6596/712/1/012074

  60. XAFS analysis for quantification of the gallium coordinations in Al<sub>2</sub>O<sub>3</sub>-supported Ga<sub>2</sub>O<sub>3</sub>photocatalysts 査読有り

    M. Akatsuka, T. Yoshida, N. Yamamoto, M. Yamamoto, S. Ogawa, S. Yagi

    Journal of Physics: Conference Series   712 巻   頁: 012056 - 012056   2016年5月

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    担当区分:責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP Publishing  

    DOI: 10.1088/1742-6596/712/1/012056

    その他リンク: http://stacks.iop.org/1742-6596/712/i=1/a=012056?key=crossref.49278627889fb72fe760993783b12a62

  61. Hydrogen storage of Pd/Mg composite nanoparticles fabricated by gas evaporation method

    Ogawa S., Suzuki H., Tsukada C., Yoshida T., Yagi S.

    e-Journal of Surface Science and Nanotechnology   14 巻 ( 0 ) 頁: 150 - 153   2016年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:公益社団法人 日本表面真空学会  

    Mg nanoparticles covered with the Pd nanoparticles (Pd/Mg NPs) have been fabricated by the gas evaporation method using He gas. The coaxial formation of the Mg and Pd NPs enables to fabricate the Pd/Mg NPs. The surfaces of the Pd and Mg NPs are quite clean because only pure He gas has been used during the fabrication of the NPs. The surface and interface chemical states of the Pd/Mg NPs have been investigated by X-ray photoelectron spectroscopy (XPS) without the exposure to the air. The XPS investigation has revealed that the formation of the interfacial alloy state between the Mg and Pd NPs. The Pd/Mg NPs can absorb the hydrogen at the room temperature by the hydrogenation of the most of the Mg atoms inside the Pd/Mg NPs.

    DOI: 10.1380/ejssnt.2016.150

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  62. Sulfur K-edge XANES for methylene blue in photocatalytic reaction over WO<sub>3</sub> nanomaterials 査読有り

    Komori, K; Yoshida, T; Nomoto, T; Yamamoto, M; Tsukada, C; Yagi, S; Yajima, M; Kajita, S; Ohno, N

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS   365 巻   頁: 35 - 38   2015年12月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms  

    We investigated the photocatalysis of dendritic nanostructured WO3/W composite materials fabricated by He plasma irradiation to tungsten plates, followed by the surface oxidation. The samples promoted the decolorization reaction of methylene blue (MB) aqueous solution under near infrared (NIR) light irradiation. To verify the MB molecule is actually decomposed by the photocatalysis of the samples, reaction products were analyzed by S K-edge XANES measurements for the MB solution kept with the samples under the light irradiation or in the dark. By the light irradiation, the σ∗(S-C) peak in the XANES spectra reduced and a new peak originated from SO42- species was clearly observed, suggesting that S-C bonds in a MB molecule are broken by the NIR light irradiation and finally the sulfur species exists in the solution in the state of SO42- ion. After the adsorption reaction in the dark, the XANES spectra of the sample surfaces showed a sharp π∗(S-C) peaks, indicating that MB molecules are adsorbed on the sample surfaces and stacked each other by the π-π interaction. These results demonstrate that the photocatalytic decomposition of MB molecules really proceeds over WO3/W composite materials even under NIR light irradiation.

    DOI: 10.1016/j.nimb.2015.07.035

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  63. Characterization of nitrogen ion implanted TiO<sub>2</sub> photocatalysts by XAFS and XPS 査読有り

    Yoshida, T; Niimi, S; Yamamoto, M; Ogawa, S; Nomoto, T; Yagi, S

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS   365 巻   頁: 79 - 81   2015年12月

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    担当区分:筆頭著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms  

    A nitrogen doped TiO2 as a visible-light response photocatalyst was prepared by N+ implantation technique. N+-implanted TiO2 samples promoted the photocatalytic activity for degradation of methylene blue under visible-light irradiation. XANES and XPS analyses indicated two types of chemical state of nitrogen, one photo-catalytically active N substituting the O sites and the other inactive NOx (1 ≤ x ≤ 2) species. In the valence band XPS spectrum of the high activity sample, the additional electronic states were observed just above the valence band edge of a TiO2. The electronic state would be originated from the substitutional nitrogen and be responsible for the band gap narrowing, i.e., visible light response of TiO2 photocatalysts.

    DOI: 10.1016/j.nimb.2015.04.010

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  64. Increase in the work function of W/WO<sub>3</sub> by helium plasma irradiation 査読有り

    Kajita, S; Ohta, A; Ishida, T; Makihara, K; Yoshida, T; Ohno, N

    JAPANESE JOURNAL OF APPLIED PHYSICS   54 巻 ( 12 ) 頁: 126201 - 126201   2015年12月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Japanese Journal of Applied Physics  

    Helium plasma irradiation to tungsten leads to formation of helium clusters, helium bubbles, and fiberform nanostructures near the surface. In this study, tungsten samples exposed to helium plasmas are analyzed by X-ray photoelectron spectroscopy in detail. The W 4f spectra and valence band spectra show chemical composition and electronic state of the surface. It was found that significant differences were not identified on the electronic state between the helium plasma irradiated and pristine samples when the degree of oxidization was the same level. From a low kinetic energy cut-off of X-ray photoelectron spectrum, the work function of the samples was measured. It was found that helium plasma irradiation increased the work function by approximately 0.5 eV when WO3/W was higher than unity. The possible mechanism to arise the difference in the work function is discussed.

    DOI: 10.7567/JJAP.54.126201

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    その他リンク: http://stacks.iop.org/1347-4065/54/i=12/a=126201?key=crossref.8de312670aa262f2ebe1e2556b349c69

  65. In situ UV-vis investigation of growth of gold nanoparticles prepared by solution plasma sputtering in NaCl solution 査読有り

    Mizutani, T; Ogawa, S; Murai, T; Nameki, H; Yoshida, T; Yagi, S

    APPLIED SURFACE SCIENCE   354 巻   頁: 397 - 400   2015年11月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Applied Surface Science  

    Gold nanoparticles are prepared in various concentrations of NaCl solutions by solution plasma sputtering. The absorption spectra of these solutions during and after the plasma process are measured by in situ ultraviolet-visible (UV-vis) spectroscopy to estimate the particle diameters and concentrations of gold. The distributions of particle diameters are obtained by transmission electron microscope (TEM) observations. These experiments indicate the gold nanoparticles with about 2.2 nm are directly formed by plasma phase and the diameters are increasing over time. These increases of particle diameters are caused by Ostwald ripening of gold nanoparticles in NaCl solution. We estimate the equilibrium diameter at which the gold nanoparticles are not solved in NaCl solution using in situ UV-vis spectroscopy. These diameters are about 5, 7 and 10 nm in 3, 5 and 10 mM NaCl solution, respectively. We make it possible to control the diameter of gold nanoparticles prepared by solution plasma sputtering in NaCl solution.

    DOI: 10.1016/j.apsusc.2015.04.139

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  66. Effects of nitrogen-related defects on visible light photocatalytic response in N<SUP>+</SUP> implanted TiO<sub>2</sub>: A first-principles study 査読有り

    Senga, J; Tatsumi, K; Muto, S; Yoshida, T

    JOURNAL OF APPLIED PHYSICS   118 巻 ( 11 )   2015年9月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Applied Physics  

    It was found that the visible-light responsiveness of a nitrogen ion-implanted TiO2 photocatalyst was attributable to the predominant chemical states of nitrogen, depending on the local nitrogen concentration near the surface. In the present study, we examined the effects of conceivable nitrogen-related defects on the visible light responsiveness, based on electronic structures calculated from first principles. Possible chemical states were proposed by comparing previously reported experiments with the present theoretical N-K X-ray absorption spectra. The theoretically predicted visible light absorption spectra and carrier trap states due to the bandgap states associated with the defects well explained the relationship between the catalytic reactivity and the proposed chemical states.

    DOI: 10.1063/1.4930811

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  67. Hydrogen storage property of materials composed of Mg nanoparticles and Ni nanoparticles fabricated by gas evaporation method 査読有り

    Fujimoto, T; Ogawa, S; Kanai, T; Uchiyama, N; Yoshida, T; Yagi, S

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY   40 巻 ( 35 ) 頁: 11890 - 11894   2015年9月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:International Journal of Hydrogen Energy  

    We have fabricated the materials composed of the Mg and the Ni nanoparticles and clarified the hydrogen storage property by using TEM, XPS and QCM. The Mg and the Ni nanoparticles have been fabricated by gas evaporation method and been mixed. The diameters of the Mg and the Ni nanoparticles have been estimated as 20.0 ± 8.4 and 4.7 ± 2.0 nm, respectively. And the Mg and the Ni nanoparticles as prepared sample possess almost clean surface. This sample can absorb the hydrogen under atmospheric pressure at 30 °C before completely oxidized. However, the hydrogen storage ability of this sample has been lost by the adsorption of residual gases even under vacuum condition in several hours after the end of fabrication. Due to the Mg oxide shell on the surface of the Mg nanoparticles is formed by the residual gases, the hydrogenation of the Mg nanoparticles are hindered.

    DOI: 10.1016/j.ijhydene.2015.05.031

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  68. Hydrogen storage of binary nanoparticles composed of Mg and Pd 査読有り

    Ogawa, S; Fujimoto, T; Mizutani, T; Ogawa, M; Uchiyama, N; Kato, K; Ohta, T; Yoshida, T; Yagi, S

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY   40 巻 ( 35 ) 頁: 11895 - 11901   2015年9月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:International Journal of Hydrogen Energy  

    The hydrogen storage property of the binary nanoparticles composed of Mg and Pd has been investigated by the QCM technique without the exposure to the air. The two types of nanoparticles have been fabricated by the gas evaporation method with the He gas. The one is the nanoparticles composed of the both Mg and Pd atoms (Mg-Pd NPs) and the other one is the composite of the Mg and Pd nanoparticles (Mg NPs-Pd NPs). Both the Mg-Pd NPs and the Mg NPs-Pd NPs can absorb the hydrogen under the room temperature and 1 atm of H2 gas. However, the desorptions of the hydrogen have not been observed about the both samples. We have also studied the chemical state of the NPs by XPS and XAFS. The XAFS analyses have revealed that the MgH2 in the NPs can not be dehydrogenated at the room temperature even if the catalytic effect of the Pd.

    DOI: 10.1016/j.ijhydene.2015.04.087

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  69. The loading effect of silver nanoparticles prepared by impregnation and solution plasma methods on the photocatalysis of Ga<sub>2</sub>O<sub>3</sub> 査読有り

    Yamamoto, M; Yoshida, T; Yamamoto, N; Nomoto, T; Yagi, S

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS   359 巻   頁: 64 - 68   2015年9月

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    担当区分:責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms  

    Ag loaded Ga2O3 (Ag/Ga2O3) photocatalysts for the reduction of CO2 with water have been prepared by impregnation (IMP) and two types of solution plasma methods (SPM1 and SPM2). Using X-ray absorption near edge structure (XANES) and Fourier transform infrared (FT-IR) spectroscopies, we have investigated the local electronic structures of Ag/Ga2O3 photocatalysts as well as the adsorption behaviors of CO2 during the reaction. Both Ag L3-edge and O K-edge XANES analyses reveal the Ag-Ga2O3 interaction, i.e., the charge-transfer from O atoms to Ag atoms, by demonstrating the decrease in the unoccupied Ag 4d-state density and increase in the unoccupied O 2p-state density. The strength of the interaction depends on the preparation method, and increases in the order of Ag/Ga2O3 (SPM2), Ag/Ga2O3 (SPM1) and Ag/Ga2O3 (IMP). In addition, FT-IR measurements have disclosed that Ag/Ga2O3 (IMP) obtains a larger amount of strongly basic sites as a result of the strongest interaction between Ag and Ga2O3. Although the amount of the adsorbed CO2 is different in each Ag/Ga2O3 sample, in the following formation process of bidentate formate species, no remarkable difference is detected among all samples. The bidentate formate species are likely to interact with H2O molecules to produce CO under photoirradiation, and this process would be affected by the strength of the Ag-Ga2O3 interaction, because this reaction hardly proceeds over Ag/Ga2O3 (SPM2) having the weakest Ag-Ga2O3 interaction.

    DOI: 10.1016/j.nimb.2015.07.031

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  70. Effective nitrogen doping into TiO<sub>2</sub> (N-TiO<sub>2</sub>) for visible light response photocatalysis 査読有り

    Yoshida, T; Niimi, S; Yamamoto, M; Nomoto, T; Yagi, S

    JOURNAL OF COLLOID AND INTERFACE SCIENCE   447 巻   頁: 278 - 281   2015年6月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Colloid and Interface Science  

    The thickness-controlled TiO2 thin films are fabricated by the pulsed laser deposition (PLD) method. These samples function as photocatalysts under UV light irradiation and the reaction rate depends on the TiO2 thickness, i.e., with an increase of thickness, it increases to the maximum, followed by decreasing to be constant. Such variation of the reaction rate is fundamentally explained by the competitive production and annihilation processes of photogenerated electrons and holes in TiO2 films, and the optimum TiO2 thickness is estimated to be ca. 10nm. We also tried to dope nitrogen into the effective depth region (ca. 10nm) of TiO2 by an ion implantation technique. The nitrogen doped TiO2 enhanced photocatalytic activity under visible-light irradiation. XANES and XPS analyses indicated two types of chemical state of nitrogen, one photo-catalytically active N substituting the O sites and the other inactive NOx (1≤x≤2) species. In the valence band XPS spectrum of the high active sample, the additional electronic states were observed just above the valence band edge of a TiO2. The electronic state would be originated from the substituting nitrogen and be responsible for the band gap narrowing, i.e., visible light response of TiO2 photocatalysts.

    DOI: 10.1016/j.jcis.2014.12.097

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  71. Spectroscopic and morphological studies on interaction between gold nanoparticle and liposome constructed with phosphatidylcholine 査読有り

    C Tsukada, T Tsuji, K Matsuo, T Nomoto, G Kutluk, M Sawada, S Ogawa, T Yoshida, S Yagi

    IOP Conference Series: Materials Science and Engineering   76 巻   頁: 012001 - 012001   2015年3月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP Publishing  

    DOI: 10.1088/1757-899x/76/1/012001

    その他リンク: http://stacks.iop.org/1757-899X/76/i=1/a=012001?key=crossref.7841256626afcf78ba29911c124eb567

  72. Hydrogen storage property of the Pd nanoparticle with clean surfaces studied by QCM

    Ogawa S., Fujimoto T., Kanai T., Uchiyama N., Tsukada C., Yoshida T., Yagi S.

    e-Journal of Surface Science and Nanotechnology   13 巻 ( 0 ) 頁: 343 - 346   2015年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:公益社団法人 日本表面真空学会  

    The hydrogen absorption behavior of the Pd NPs has been investigated by the noble techniques. The Pd NPs with the clean surface have been fabricated by the gas evaporation method. The P-C isotherm of the hydrogen absorption of the Pd NPs has been obtained using the QCM without the exposure to the air. The P-C isotherms have shown the clear size dependent absorption behavior for the Pd NPs. Further absorption and desorption cycles decrease the solubility of H significantly in the Pd NPs.

    DOI: 10.1380/ejssnt.2015.343

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  73. Photocatalytic reduction of CO<sub>2</sub> with water promoted by Ag clusters in Ag/Ga<sub>2</sub>O<sub>3</sub> photocatalysts 査読有り

    Yamamoto, M; Yoshida, T; Yamamoto, N; Nomoto, T; Yamamoto, Y; Yagi, S; Yoshida, H

    JOURNAL OF MATERIALS CHEMISTRY A   3 巻 ( 32 ) 頁: 16810 - 16816   2015年

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Materials Chemistry A  

    Ag loaded Ga2O3 (Ag/Ga2O3) photocatalysts were prepared by an impregnation method and examined for the photocatalytic reduction of CO2 with water where CO, H2 and O2 were formed as products. TEM and X-ray absorption near edge structure (XANES) measurements revealed that around 1 nm sized Ag clusters were formed predominantly in an active Ag/Ga2O3 sample while partially oxidized large Ag particles with the size of several-several tens of nm were observed in a less active Ag/Ga2O3 sample. Both Ag L3-edge and O K-edge XANES analyses suggested that the small Ag clusters accepted more electrons in the d-orbitals as a result of the strong interaction with the Ga2O3 surface. In situ FT-IR measurements of the Ag/Ga2O3 samples showed CO3 stretching vibration bands assignable to monodentate bicarbonate and bidentate carbonate species chemisorbed on the Ga2O3 surface, and to monodentate carbonate species on the large Ag particles. Among these chemisorbed species, the monodentate bicarbonate and/or the bidentate carbonate species changed to bidentate formate species, as the reaction intermediate, under UV light irradiation. The bidentate formate species was formed not by the plasmonic excitation of the Ag nanoparticles but by the photoexcitation of the Ga2O3 semiconductor, and the formation process would be promoted at the perimeter of the Ag clusters on the Ga2O3 surface by the effective separation of electron-hole pairs.

    DOI: 10.1039/c5ta04815j

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  74. Hydrogen storage property of materials composed of Mg nanoparticles and Ni nanoparticles fabricated by gas evaporation method 査読有り

    吉田 朋子

    International Journal of Hydrogen Energy   40 巻   頁: 11890 - 11894   2015年

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  75. Hydrogen storage of binary nanoparticles composed of Mg and Pd 査読有り

    吉田 朋子

    International Journal of Hydrogen Energy   40 巻   頁: 11895 - 11901   2015年

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  76. Depth distribution of dopant effective for visible-light response in nitrogen-doped TiO<sub>2</sub> photocatalyst 査読有り

    Yoshida, T; Kuda, E; Muto, S

    SURFACE AND INTERFACE ANALYSIS   46 巻 ( 12-13 ) 頁: 1236 - 1239   2014年12月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Surface and Interface Analysis  

    Nitrogen was doped into TiO2 by an ion implantation technique to investigate the depth distribution of nitrogen most effective for fabricating a visible-light responsive photocatalyst. In the nitrogen-doped TiO2 samples, the photocatalytic activity under visiblelight irradiation was enhanced, wherein two types of chemical state of nitrogen, one photocatalytically active and the other inactive, were found depending on the nitrogen concentration, using electron energy loss spectroscopy. The depth distributions of nitrogen were quantified, so that the implanted nitrogen increased with thickness from the surface up to 90 nm, consistent with Monte Carlo simulations. The critical nitrogen concentration for the photocatalytically active species to form was estimated to be no higher than 1.8 atom%.We also derived semi-empirical equations fromthe present results to estimate the critical depth of nitrogen distribution effectively reactive to be 13 ± 5 nm from the surface.

    DOI: 10.1002/sia.5542

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  77. XAFS and XPS study of hydro-/dehydrogenation reaction of Mg-Pd nanoparticles 査読有り

    Ogawa, S; Fujimoto, T; Mizutani, T; Ogawa, M; Yogi, C; Kato, K; Ohta, T; Yoshida, T; Yagi, S

    SURFACE AND INTERFACE ANALYSIS   46 巻 ( 12-13 ) 頁: 1143 - 1146   2014年12月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Surface and Interface Analysis  

    The nanoparticles composed of Mg and Pd atoms (Mg-Pd NPs) have been fabricated by the gas evaporation method, and the variation of the chemical state during hydro-/dehydrogenations has been investigated by X-ray photoelectron spectroscopy (XPS) and in-situ X-ray absorption fine structure (XAFS) analyses. Both XPS and XAFS spectra have indicated that the Mg-Pd NPs contain the chemical state of the metallic Pd and Mg-Pd alloy phases. The Mg-Pd alloy phase has been identified as MgPd and Mg6Pd by the Pd K-edge EXAFS analysis. The hydrogen release of the Mg-Pd NPs has not been observed after first hydrogenation due to the migration of Mg toward the surface of the Mg-Pd NPs during the hydrogen storage. This irreversible migration has led the inhibition of the hydrogen diffusion into the surface from the inside of the Mg-Pd NPs.

    DOI: 10.1002/sia.5647

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  78. Preparation of gold nanoparticles included in anatase-phase titania by solution plasma method 査読有り

    Mizutani, T; Murai, T; Nomoto, T; Nameki, H; Yoshida, T; Yagi, S

    SURFACE AND INTERFACE ANALYSIS   46 巻 ( 12-13 ) 頁: 1125 - 1128   2014年12月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Surface and Interface Analysis  

    The gold nanoparticles on titania support (AuNP/TiO2) has been paid attention as a catalyst and a photocatalyst. We perform the preparation of AuNP/TiO2, which is the combination of the sol-gel method and solution plasma method. In this method, we generate the plasma in the gelatinous peroxotitanic acid solution by the discharge between the gold electrodes, and then we synthesize the peroxotitanium gel containing gold nanoparticles. After drying and calcination process, we obtain the AuNP/TiO2 samples. The X-ray diffraction results show that the AuNP/TiO2 is constituted by the nanocrystalline gold and anatase-phase TiO2, and the lattice constant decreases by the embedded gold nanoparticles in the TiO2 matrix. Ultraviolet-Visible absorption spectroscopy shows that the AuNP/TiO2 samples absorb the visible light at about 630nm based on the localized surface plasmon resonance of gold nanoparticles embedded in the TiO2 matrix. The surface chemical states of the AuNP/TiO2 samples are analyzed by the X-ray photoelectron spectroscopy. The surface of AuNP/TiO2 is composed with the majority of oxidized gold and minority of metallic gold which interacted with the TiO2 surface. The Au L3-edge near edge X-ray absorption fine structure spectra indicate that the gold nanoparticles embedded in TiO2 have metallic chemical states. We successfully prepare the gold nanoparticles on the surface and in the matrix of anatase-phase TiO2.

    DOI: 10.1002/sia.5567

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  79. Hydrogen storage property of Ni nanoparticles fabricated by the gas evaporation method 査読有り

    Fujimoto, T; Ogawa, S; Yoshida, T; Uchiyama, N; Yagi, S

    SURFACE AND INTERFACE ANALYSIS   46 巻 ( 12-13 ) 頁: 1121 - 1124   2014年12月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Surface and Interface Analysis  

    We have fabricated the Ni nanoparticles with a clean surface by the gas evaporation method and clarified the hydrogen storage property by using atomic forcemicroscope (AFM), X-ray photoelectron spectroscopy (XPS) and quartz crystal microbalance(QCM)measurements. The diameter has been estimated as 4.0 ± 1.5nm by AFM observation. The Ni nanoparticles possess a clean surface, because the surface chemical state has been confirmed asmainlymetallic state by XPS. The hydrogen storage property has been investigated by QCM fromthe vacuum to the atmospheric pressure of the hydrogen at 300 K. The plateau pressure of the Ni nanoparticles and amaximum hydrogen storage capacity are about 7 Torr and H/Ni = 0.56, respectively. And the hydrogen release from the Ni nanoparticles has not been observed by QCM. The hydrogen adsorption/desorption reaction have also been observed as the plateau like pressure by QCM. These results indicate that (i) the plateau pressure of Ni is decreased by the nanosizing of the material, (ii) the large specific surface area of the Ni nanoparticlesmakes it possible to observe the adsorption/desorption reaction and (iii) the Ni hydride is stable under the vacuum condition. The chemical shift of Ni 2p3/2 has not been observed in the XPS spectrum between before and after exposure to the hydrogen. This result implies that there is no strong chemical bonding between Ni and hydrogen or the hydrogen in the lateral surface has been released.

    DOI: 10.1002/sia.5566

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  80. In situ ultraviolet-visible absorbance measurement during and after solution plasma sputtering for preparation of colloidal gold nanoparticles 査読有り

    Mizutani, T; Murai, T; Nameki, H; Yoshida, T; Yagi, S

    JAPANESE JOURNAL OF APPLIED PHYSICS   53 巻 ( 11 ) 頁: 11RA03 - 11RA03   2014年11月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Japanese Journal of Applied Physics  

    The absorption spectra of the HCl, NaCl, and NaOH solutions during and after the solution plasma sputtering for the preparation of gold nanoparticles are measured by in situ ultraviolet-visible (UV-vis) spectroscopy to determine the particle diameter and behavior. In the solution plasma sputtering, gold particles are directly formed from the plasma phase and not by the reduction of Au3+ ions dissolved from electrodes. The initial diameter and behavior differ according to the solution used. In HCl solution, gold nanoparticles are formed and dissolve into Au3+ ions. When the solution is saturated, the gold nanoparticles grow by the aggregation of Au3+ ions. Cluster-sized particles are formed in NaCl solution that constitute nanoparticles, which are very stable for several days. Gold nanoparticles of 3 nm diameter are formed in NaOH solution, which aggregate over several days. The contribution of chlorine ions to the day-order stability of gold nanoparticles is suggested.

    DOI: 10.7567/JJAP.53.11RA03

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    その他リンク: http://stacks.iop.org/1347-4065/53/i=11S/a=11RA03?key=crossref.abf0db48a09f1feadf9e0e6809c9acc1

  81. Surface modification of titanium using He plasma 査読有り

    Kajita, S; Kitaoka, D; Ohno, N; Yoshihara, R; Yoshida, N; Yoshida, T

    APPLIED SURFACE SCIENCE   303 巻   頁: 438 - 445   2014年6月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Applied Surface Science  

    Helium plasma irradiation to metals could be a potential novel surface modification method in nanoscale. In this study, systematic helium plasma irradiations to titanium were conducted in low ion energy (<100 eV) and high fluence (>10 25 m -2 ) regime. From the surface analysis by scanning electron microscopy and transmission electron microscopy, various types of morphology changes, i.e. nanocone, pinhole, porous structure, and rough surfaces, were identified. The experimental conditions that control the various morphology changes are revealed from the aspect of the incident ion energy and the surface temperature. Based on the observations, it is thought that helium bubble growth, surface diffusion, and physical sputtering played important roles for the morphology change. © 2014 Elsevier B.V.

    DOI: 10.1016/j.apsusc.2014.03.022

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  82. 29pAE-4 ヘリウム照射により発現するタングステンナノ構造の光触媒特性(29pAE 領域2,領域10合同シンポジウム:ヘリウムプラズマ照射により誘起される金属表面ナノ構造の新展開,領域2(プラズマ))

    吉田 朋子, 小森 勝之, 八木 伸也, 矢嶋 美幸, 北岡 大輝, 梶田 信, 大野 哲靖

    日本物理学会講演概要集   69.1.2 巻 ( 0 ) 頁: 270   2014年

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    記述言語:日本語   出版者・発行元:一般社団法人 日本物理学会  

    DOI: 10.11316/jpsgaiyo.69.1.2.0_270_1

    CiNii Research

  83. Application of nanostructured tungsten fabricated by helium plasma irradiation for photoinduced decolorization of methylene blue e-J

    Komori K., Yoshida T., Yagi S., Yoshida H., Yajima M., Kajita S., Ohno N.

    e-Journal of Surface Science and Nanotechnology   12 巻 ( 0 ) 頁: 343 - 348   2014年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:公益社団法人 日本表面真空学会  

    The dendritic nanostructure was fabricated on a surface of tungsten plate by helium plasma irradiation. The nanostructure consisting of W metal was partially oxidized to form WO3 on exposure to air, and the resulting surface exhibited a broad photoabsorption in the range from 1 to 5 eV. We examined photoinduced reaction of methylene blue (MB) on the material. It was found that the partially and fully oxidized surface nanostructures were able to promote a decolorization of MB under photoirradiation even with the near-infrared light (< 1:55 eV), whose energy is lower than the band gap of WO3. The reaction rate was varied with the fraction of W and WO 3 on the surface layers, that is, the partially oxidized sample promoted the reaction at a higher rate than the fully oxidized one. It is also found that the reaction rate decreased with time, which would be caused by the products accumulation on the surface and the surface oxidation. © 2014 The Surface Science Society of Japan.

    DOI: 10.1380/ejssnt.2014.343

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    CiNii Research

  84. The influence of the preparing method of a Ag/Ga2O3 catalyst on its activity for photocatalytic reduction of CO2 with water

    Yamamoto N., Yoshida T., Yagi S., Like Z., Mizutani T., Ogawa S., Nameki H., Yoshida H.

    e-Journal of Surface Science and Nanotechnology   12 巻 ( 0 ) 頁: 263 - 268   2014年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:公益社団法人 日本表面真空学会  

    We have prepared silver-loaded gallium oxide (Ag/Ga2O 3) photocatalysts by the solution plasma method (SPM) and impregnation method (imp), and investigate the effects of the chemical states and the size of the Ag nanoparticles on their photocatalytic activities. The photocatalytic reduction of CO2 with water proceeds over all the Ag/Ga2O3 photocatalysts to produce CO, however the CO production rates decrease during photocatalytic reaction. Measurements of UV-VIS diffuse reflectance spectra, XANES spectra and TEM images reveal the followings: the Ag oxide nanoparticles in the as-prepared Ag/Ga 2O3 (imp) samples exist and their size distribution is wide from 5 to 10 nm. They become a lot of metallic nanoparticles by UV light-irradiation, and become larger particles with the size of ca. 20 nm during the photocatalytic reaction. On the other hand, the Ag nanoparticles in the as-prepared Ag/Ga2O3 (SPM) samples are metallic with the size of less than 10 nm. The size does not change under UV light irradiation, while become larger particles during the photocatalytic reaction as similar to the case of the Ag/Ga2O3 (imp) samples. Such small metallic Ag nanoparticles with the size of 5-10 nm are suitable for CO production. However, they aggregate during the reaction for 5 h to degrade the photocatalytic activity. © 2014 The Surface Science Society of Japan.

    DOI: 10.1380/ejssnt.2014.263

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    CiNii Research

  85. Study on interaction between phosphatidylcholine(PC) liposome and gold nanoparticles by TEM observation

    Tsukada C., Tsuji T., Matsuo K., Nameki H., Yoshida T., Yagi S.

    Journal of Surface Analysis   20 巻 ( 3 ) 頁: 230 - 233   2014年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:The Surface Analysis Society of Japan  

    <p>  The PC liposomes constructed with one lipid bilayer have been fabricated without using chloroform solution and phosphate-buffer saline. After reaction promotion, the Au NPs covered with PC molecules exist on the outside of the liposome membrane. The thickness of the liposome membrane is estimated to be approximately 5 nm.</p>

    DOI: 10.1384/jsa.20.230

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  86. In-situ FT-IR study on the mechanism of CO2 reduction with water over metal (Ag or Au) loaded Ga2O3 photocatalysts e-j

    Yamamoto M., Yoshida T., Yamamoto N., Yoshida H., Yagi S.

    e-Journal of Surface Science and Nanotechnology   12 巻 ( 0 ) 頁: 299 - 303   2014年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:公益社団法人 日本表面真空学会  

    Ag loaded Ga2O3 (Ag/Ga2O3) has exhibited photocatalytic activity for CO2 reduction with water to produce COas well as for water splitting to H2 and O2. In-situ FT-IR measurements have shown CO3 stretching vibration bandsassignable to carbonate and bicarbonate species when CO2 molecules chemisorbed on the catalyst surface. Thesespecies change to bidentate formate species under photoirradiation. It subsequently converts to CO by interactingwith water molecules, not chemisorbed OH on the catalyst surface. This result suggests that formate species isan intermediate of the photocatalytic CO2 reduction. On the other hand, Au loaded Ga2O3 (Au/Ga2O3) hasproduced H2 predominantly with a very small amount of CO formation, since the less amount of CO2 moleculeschemisorb on Au/Ga2O3. FT-IR measurements of the Ag/Ga2O3 with high Ag loading have shown carbonatespecies due to the adsorption of atmospheric CO2 on hydroxyl group. The carbonate species is too unstable underphotoirradiation to convert into formate species, but is stabilized as CO2-3 species by the reaction with water.XANES analysis has revealed that atomically dispersed Ag metal species may be effective for the adsorption ofCO2 and the subsequent conversion into formate species to promote the photocatalytic CO2 reduction. © 2014 The Surface Science Society of Japan.

    DOI: 10.1380/ejssnt.2014.299

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    CiNii Research

  87. Hydrogen storage property of Mg-Pd nanoparticles studied by spectroscopic techniques

    Ogawa S., Fujimoto T., Mizutani T., Ogawa M., Uchiyama N., Kato K., Ohta T., Yoshida T., Yagia S.

    20th World Hydrogen Energy Conference, WHEC 2014   2 巻   頁: 1077 - 1082   2014年

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    出版者・発行元:20th World Hydrogen Energy Conference, WHEC 2014  

    The hydrogen storage property of the nanoparticles composed of the Mg and Pd atoms (Mg-Pd NPs) has been investigated by QCM technique without the exposure to the air. We have also studied the chemical state of the Mg-Pd NPs by XPS and XAFS. The Mg-Pd NPs can store the hydrogen under the room temperature and 1 atm of H2 gas. However, the release of the hydrogen has not been observed. XAFS study has revealed that the irreversible change of the Mg-Pd NPs has caused the inhibition of the release of hydrogen.

    Scopus

  88. Hydrogen storage property of materials composed of Mg nanoparticles and Ni nanoparticles fabricated by gas evaporation method

    Fujimoto T., Ogawa S., Yoshida T., Yagi S.

    20th World Hydrogen Energy Conference, WHEC 2014   2 巻   頁: 1072 - 1076   2014年

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    出版者・発行元:20th World Hydrogen Energy Conference, WHEC 2014  

    We have fabricated the materials composed of the Mg and the Ni nanoparticles and clarified the hydrogen storage property by using TEM, XPS and QCM. The Mg and the Ni nanoparticles have been fabricated by the gas evaporation method and been mixed. The diameters of the Mg and the Ni nanoparticles have been estimated as 20.0±8.4 and 4.7±2.0 nm, respectively. The XPS results show that the Mg and the Ni nanoparticles as prepared sample possess almost clean surface. However, this materials has not been hydrogenated under hydrogen atmospheric pressure at 303 K. The QCM results indicate that the hydrogen storage ability of this materials has been lost by the adsorption of residual gases even under vacuum condition in several hours after the end of fabrication. The XPS results after hydrogen exposure show that due to the Mg oxide shell on the surface of the Mg nanoparticles is formed by the residual gases, the hydrogenation of the Mg nanoparticles are hindered.

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  89. Hydrogen storage of binary nanoparticles composed of Mg and Pd

    Ogawa S., Fujimoto T., Mizutani T., Ogawa M., Uchiyama N., Kato K., Ohta T., Yoshida T., Yagia S.

    20th World Hydrogen Energy Conference, WHEC 2014   2 巻   頁: 1083 - 1089   2014年

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    出版者・発行元:20th World Hydrogen Energy Conference, WHEC 2014  

    The hydrogen storage property of the binary nanoparticles composed of Mg and Pd has been investigated by QCM technique without the exposure to the air. The two types of nanoparticles have been fabricated by the gas evaporation method with He gas. The one is the nanoparticles composed of the both Mg and Pd atoms (Mg-Pd NPs) and the other one is the composite of the each Mg and Pd nanoparticles (Mg NPs-Pd NPs). We have also studied the chemical state of the nanoparticles by XPS and XAFS. Both the Mg-Pd NPs and the Mg NPs-Pd NPs can store the hydrogen under the room temperature and 1 atm of H2 gas. However, the releases of the hydrogen have not been observed about the both samples. XAFS study has revealed that the irreversible change of the Mg-Pd NPs has caused the inhibition of the release of hydrogen. On the other hand, it seems that the Mg NPs-Pd NPs cannot release the hydrogen due to the stability of the MgH2 or the low hydrogen diffusion property inside of the MgH2.

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  90. Helium plasma implantation on metals: Nanostructure formation and visible-light photocatalytic response 査読有り

    Kajita, S; Yoshida, T; Kitaoka, D; Etoh, R; Yajima, M; Ohno, N; Yoshida, H; Yoshida, N; Terao, Y

    JOURNAL OF APPLIED PHYSICS   113 巻 ( 13 ) 頁: 134301 - 134307   2013年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Journal of Applied Physics  

    It has been found recently that low-energy helium (He) plasma irradiation to tungsten (W) leads to the growth of W nanostructures on the surface. The process to grow the nanostructure is identified as a self-growth process of He bubbles and has a potential to open up a new plasma processing method. Here, we show that the metallic nanostructure formation process by the exposure to He plasma can occur in various metals such as, titanium, nickel, iron, and so on. When the irradiation conditions alter, the metallic cone arrays including nanobubbles inside are formed on the surface. Different from W cases, other processes than growth of fiberform structure, i.e., physical sputtering and the growth of large He bubbles, can be dominant on other metals during irradiation; various surface morphology changes can occur. The nanostructured W, part of which was oxidized, has revealed a significant photocatalytic activity under visible light (wavelength >700 nm) in decolorization of methylene blue without any co-catalyst. © 2013 American Institute of Physics.

    DOI: 10.1063/1.4798597

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  91. Heterogeneous palladium catalyst hybridised with titanium dioxide photocatalyst for direct C-C bond formation between aromatic ring and acetonitrile 査読有り

    H. Yoshida, Y. Fujimura, H. Yuzawa, J. Kumagai, T. Yoshida

    Chem. Commun.   49 巻   頁: 3793-3795   2013年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  92. Helium Plasma Implantation on Metals: Nanostructure Formation and Visible-light Photocatalytic Response 査読有り

    S. Kajita, T. Yoshida, D. Kitaoka, R. Etoh, M. Yashima, N. Ohno, H. Yoshida, Na. Yoshida, Y. Terao

    J. Appl. Phys.   113 巻   頁: 134301-134307   2013年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  93. Bifunctional Rhodium Cocatalysts for Photocatalytic Steam Reforming of Methane over Alkaline Titanate 査読有り

    Shimura, K; Kawai, H; Yoshida, T; Yoshida, H

    ACS CATALYSIS   2 巻 ( 10 ) 頁: 2126 - 2134   2012年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACS Catalysis  

    Photocatalytic steam reforming of methane (PSRM; 2 H 2O (g) + CH 4 → 4 H 2 + CO 2) was examined over metal-loaded K 2Ti 6O 13 photocatalysts. Although the production rate was improved by loading Pt cocatalyst on the K 2Ti 6O 13 photocatalyst, unfavorable formation of CO and gradual deactivation of photocatalyst were observed. On the other hand, a Rh-loaded K 2Ti 6O 13 sample showed two times higher activity than the Pt-loaded one did, and promoted the PSRM selectively without deactivation for many hours. In the highly active Rh-loaded photocatalyst, the Rh cocatalyst existed as a mixture of small metallic rhodium and large rhodium oxide particles. The photocatalytic activity tests for hydrogen evolution and oxygen evolution from each aqueous solution of sacrificial reagent (methanol and silver nitrate, respectively) revealed that the metallic rhodium particles and the rhodium oxide particles could function as cocatalysts preferably for reduction and oxidation, respectively. Also on a Na 2Ti 6O 13 photocatalyst, a mixture of rhodium metal and oxide similarly enhanced the photocatalytic activity. Thus, it is suggested that the Rh cocatalyst on these alkaline titanates bifunctionally promoted the PSRM. © 2012 American Chemical Society.

    DOI: 10.1021/cs2006229

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  94. Gold nanoparticles on titanium oxide effective for photocatalytic hydrogen formation under visible light 査読有り

    Yuzawa, H; Yoshida, T; Yoshida, H

    APPLIED CATALYSIS B-ENVIRONMENTAL   115 巻   頁: 294 - 302   2012年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Applied Catalysis B: Environmental  

    Photocatalytic hydrogen production from aqueous ethanol was investigated over Au-loaded titanium oxide under visible light (510-740. nm) irradiation. Hydrogen was constantly produced through the present plasmonic photocatalysis. In this system, Au nanoparticles with larger particle size were essentially effective for the reaction due to the high efficiency for the localized surface plasmon resonance (LSPR). Further, Au nanoparticles with short rod-like shapes were more effective for the reaction than those with spherical shape because of the higher efficiency for the electron transfer from the Au nanoparticle to the conduction band of titanium oxide. On the other hand, aggregates of the Au nanoparticles were not appropriate for the reaction, which derived from the low efficiency of the electron transfer. Finally, titanium oxide containing anatase phase with larger particle size was most preferred for the reaction. © 2011 Elsevier B.V..

    DOI: 10.1016/j.apcatb.2011.12.029

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  95. Bifunctional Rhodium Cocatalysts for Photocatalytic Steam Reforming of Methane over Alkaline Titanate 査読有り

    K. Shimura, H. Kawai, T. Yoshida, and H. Yoshida

    ACS Catal.   2 巻   頁: 2126-2134   2012年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  96. Nontoxic, nonvolatile, and highly efficient osmium catalysts for asymmetric dihydroxylation of alkenes and application to one mol-scale synthesis of an anticancer drug, camptothecin intermediate 査読有り

    R. Akiyama, N. Matsuki, H. Nomura, H. Yoshida, T. Yoshida, S. Kobayashi

    RSC Adv.   2 巻   頁: 7456-7461   2012年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  97. Gold nanoparticles on titanium oxide effective for photocatalytic hydrogen formation under visible light 査読有り

    H. Yuzawa, T. Yoshida and H. Yoshida

    Appl. Catal. B   115-116 巻   頁: 294-302   2012年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  98. Cluster size analysis in Ge-doped silica showing 3.1 eV luminescence by RMC-XAFS and HAADF-STEM 査読有り

    T. Yoshida, S. Muto, H. Yoshida

    AMTC Letters   3 巻   頁: 208-209   2012年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  99. Cluster size analysis in Ge-doped silica showing 3.1 eV luminescence by RMC-XAFS and HAADF-STEM 査読有り

    T. Yoshida, S. Muto, H. Yoshida

    AMTC Letters   3 巻   頁: 208 - 209   2012年

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    担当区分:筆頭著者  

  100. Study on radiation damage for l-cysteine on au nanoparticle by soft x-ray

    Tsukada C., Mizutani T., Ogawa S., Nomoto T., Nameki H., Ueno T., Sawada M., Kutluk G., Namatame H., Taniguchi M., Yoshida T., Yagi S.

    NANOCON 2012 - Conference Proceedings, 4th International Conference     頁: 648 - 653   2012年

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    出版者・発行元:NANOCON 2012 - Conference Proceedings, 4th International Conference  

    We have revealed the radiation damage for the cys/Au NPs/Ni sample by the X-ray irradiation at the energy regions of N and O K-edges NEXAFS. The Au NPs colloidal solution is fabricated by the solution plasma method, and the adsorption reaction between the Au NPs and L-cysteine is promoted under water environment. About the cys/Au NPs/Ni sample after the X-ray irradiation, the radiation damages appear at N and O K-edges NEXAFS, S2p XPS and N1s XPS spectra. It is found that the L-cysteine adsorbates desorb from the Au NPs surface. This desorption occurs by means of the electron bombardment of secondary electrons excited from the Au NPs surface.

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  101. STUDY ON RADIATION DAMAGE FOR L-CYSTEINE ON AU NANOPARTICLE BY SOFT X-RAY

    Tsukada, C; Mizutani, T; Ogawa, S; Nomoto, T; Nameki, H; Ueno, T; Sawada, M; Kutluk, G; Namatame, H; Taniguchi, M; Yoshida, T; Yagi, S

    NANOCON 2012, 4TH INTERNATIONAL CONFERENCE     頁: 648 - 653   2012年

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  102. IN-SITU MG K- AND PD L<sub>3</sub>-EDGES NEXAFS INVESTIGATION OF MG-PD NANOPARTICLES

    Ogawa, S; Mizutani, T; Ogawa, M; Yogi, C; Ohta, T; Yoshida, T; Yagi, S

    NANOCON 2012, 4TH INTERNATIONAL CONFERENCE     頁: 274 - 279   2012年

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  103. In-situ Mg K- and Pd L<inf>3</inf>-edges NEXAFS investigation of MG-PD nanoparticles

    Ogawa S., Mizutani T., Ogawa M., Yogi C., Ohta T., Yoshida T., Yagi S.

    NANOCON 2012 - Conference Proceedings, 4th International Conference     頁: 274 - 279   2012年

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    出版者・発行元:NANOCON 2012 - Conference Proceedings, 4th International Conference  

    The chemical state around the Mg and Pd atoms in the Mg-Pd nanoparticles has been investigated by the Mg K- and Pd L3-edges NEXAFS techniques under in-situ condition. The Mg-Pd nanoparticles possess metallic Mg and Pd states and the surface of the Mg-Pd nanoparticles is partly oxidized. Moreover, both the Mg K- and Pd L3-edges NEXAFS spectra show that the Mg-Pd alloy phases are formed in the Mg-Pd nanoparticles. The variation of the chemical states around the Pd atom after the cycles of the exposure to the H2 gas has been also investigated by the Pd L3-edge NEXAFS technique. The Mg-Pd alloy phases dissociate by the cycles of hydrogenation and dehydrogenation.

    Scopus

  104. Simultaneously photodeposited rhodium metal and oxide nanoparticles promoting photocatalytic hydrogen production 査読有り

    K. Shimura, H. Kawai, T. Yoshida, H. Yoshida

    Chem. Commun.   47 巻   頁: 8958-8960   2011年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  105. 放射光・電子分光法融合による触媒活性種の化学状態解析 査読有り

    吉田朋子、武藤俊介

    触媒   53 巻   頁: 228-234   2011年

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    担当区分:筆頭著者   記述言語:日本語   掲載種別:研究論文(学術雑誌)  

  106. Nitrogen doped TiO2 photocatalyst prepared by low energy N+ implantation technique 査読有り

    T. Yoshida and E. Kuda

    Stud. Surf. Sci. Catal.   175 巻   頁: 267-270   2010年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  107. Photocatalytic Activation of Water and Methane over Modified Gallium Oxide for Hydrogen Production 査読有り

    K. Shimura, T. Yoshida and H. Yoshida

    J. Phys. Chem. C   114 巻   頁: 11466-11474   2010年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  108. Synchrotron-radiation-stimulated etching of polydimethylsiloxane using XeF2 as a reaction gas 査読有り

    T-Y Chiang, T. Makimura, T. He, S. Torii, T. Yoshida, R. Tero, C. Wang and T. Urisu

    J. Synchrotron Rad.   17 巻   頁: 69-74   2010年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  109. Photocatalytic Steam Reforming of Methane over Sodium Tantalate 査読有り

    K. Shimura, S. Kato, T. Yoshida, H. Itoh, T. Hattori and H. Yoshida

    J. Phys. Chem. C   114 巻   頁: 3493-3503.   2010年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  110. Clustering of germanium atoms in silica glass responsible for the 3.1 eV emission band studied by optical absorption and X-ray absorption fine structure analysis 査読有り

    T. Yoshida, S. Muto, L. Yuliati, H. Yoshida and Y. Inada

    J. Nucl. Mater.   386-388 巻   頁: 1010-1013   2009年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  111. Diagnostic Nano-Analysis of Materials Properties by Multivariate Curve Resolution Applied to Spectrum Images by S/TEM-EELS 査読有り

    S. Muto, T. Yoshida and K. Tatsumi

    Mater. Trans.   50 巻   頁: 964-969   2009年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  112. Formation of germanium nanoparticles in silica glass studied by optical absorption and X-ray absorption fine structure analysis 査読有り

    T. Yoshida, S. Muto, L. Yuliati, H. Yoshida and Y. Inada

    Nucl. Instr. and Meth. B   267 巻   頁: 1368-1371   2009年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  113. 複合電子分光による機能元素分析と物性画像診断 査読有り

    武藤俊介、吉田朋子、巽 一厳

    日本金属学会誌   48 巻   頁: 290-293   2009年

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

  114. Hydrogen trapping state associated with the low-temperature TDS peak in hydrogenated nanostructured graphite 査読有り

    Y. Miyabe, T. Yoshida, S. Muto, T. Kiyobayashi and H. Wasada

    Journal of Applied Physics   104 巻   頁: 044311   2008年7月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  115. X-ray excited 3.2-eV luminescence from amorphous silica: radiative electron relaxation through unidentified centre and its thermal switching 査読有り

    M. Ishii, T. Yoshida and K. Sakurai

    Journal of Physics: Condensed Matter   20 巻   頁: 255249   2008年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  116. Local atomic and electronic structure around Mg and Al dopants in LiNiO2 electrodes studied by XANES and ELNES and first-principles calculations 査読有り

    K. Tatsumi, Y. Sasano, S. Muto, T. Yoshida, T. Sasaki, K. Horibuchi, Y. Takeuchi and Y. Ukyo

    Phys. Rev. B,   B78 巻   頁: 1-9   2008年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  117. *Chemical state analysis of implanted nitrogen in visible-light response TiO2 photo-catalyst 査読有り

    T. Yoshida and S. Muto

    Trans. Mater. Res. Soc. Japan   33 巻 ( 2 ) 頁: 339-344.   2008年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    It was found that nitrogen-doped TiO2 revealed significant improvement in high photocatalytic reactivity under visible-light [Asahi et al, Science 293, 269-271 (2001).] To investigate the optimal local concentration of doped nitrogen for visible-light response, N+-implanted TiO2 samples were examined by means of X-ray absorption near edge structure (XANES) and electron energy loss spectroscopy (EELS). Depth-resolved N K-edge in EELS revealed two types of chemical state of nitrogen, depending on the concentration, which was consistent with the XANES results. We found that the local nitrogen concentration effective for visible-light response was less than &#61566;1 at%. Further, we visualized the spatial distributions of the different chemical states of nitrogen by energy-filtering TEM (EFTEM). It was also found that the photocatalytic active state was offset by the coexisting photocatalytic inactive state.

  118. *Chemical state analysis of implanted nitrogen in visible-light response TiO2 photo-catalyst 査読有り

    T. Yoshida, S. Muto

    Trans. Mater. Res. Soc. Japan   33 巻 ( 2 ) 頁: 339-344.   2008年

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    担当区分:筆頭著者  

  119. Hydrogen Quasi-Chemically Trapped Between Defective Graphene Layers in Nanostructured Graphite 査読有り

    Y. Miyabe, T. Yoshida, S, Muto and T. Kiyobayashi

    Mater. Sci. Forum   561-565 巻   頁: 1585-1588   2007年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Direct evidences of hydrogen loosely trapped between graphene layers in nanostructured graphite prepared by mechanical milling in a hydrogen atmosphere are presented, based on a combinational study of FT-IR, electron diffraction (ED) and electron energy-loss spectroscopy (EELS). The FT-IR spectrum of nanostructured graphite exhibited a new broad absorption band at very low frequencies around 660 cm-1, which almost disappeared by annealing up to 800 K. ED and plasmon peaks in EELS detected the unusual shrinkage and subsequent expansion of the fragmented graphene interlayer distance by hydrogen incorporation and desorption with annealing, well correlated with the change in intensity of the 660 cm-1 IR band. All the present results support our previous studies

  120. Depth selective electronic state analysis of implanted nitrogen in visible-light response TiO2 photocatalyst 査読有り

    T. Yoshida, S. Muto and J. Wakabayashi

    Mater. Sci. Forum   561-565 巻   頁: 567-570   2007年5月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Energetic nitrogen ion was injected into a TiO2 photocatalyst in order to investigate the optimal local concentration of doped nitrogen for visible-light response. N+-implanted TiO2 samples promoted the photocatalytic activity under visible-light irradiation. N K-edge XANES of the highest activity sample indicated that N replaces the O sites near the surface, whereas in the samples of higher N+ fluence, N-O and/or N-N species formed. Depth-resolved N K-edge ELNES revealed the two types of N, depending on the concentration, and we found the local N concentration effective for visible-light response was less than ~1 at%. Further, the spatial distributions of the different chemical states of N by energy-filtering TEM (FETEM) supported these findings.

  121. Measurement of soft X-ray excited optical luminescence of a silica glass 査読有り

    T. Yoshida, S. Muto and T.Tanabe

    AIP conf. Proc.   882 巻   頁: 572-574   2007年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  122. Enhancement of gamma-ray radiolysis of carbon dioxide with the assistance of solid materials 査読有り

    D. Watanabe, T. Yoshida, C. Allen and T. Tanabe

    J. Radioanal. Nucl. Chem.   272 巻   頁: 461-465   2007年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  123. Detection of hydrogen at localized regions by unoccupied electronic states in iron carbides, towards high spatial resolution mapping of hydrogen distributions 査読有り

    K. Tatsumi, S. Muto and T. Yoshida

    J. Appl. Phys.   101 巻   頁: 023523   2007年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  124. 位置選択的電子エネルギー損失分光法によるナノ表面・界面電子状態測定とその空間分布の可視化 招待有り 査読有り

    武藤俊介,吉田朋子

    表面   45 巻   頁: 1-12   2007年

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    記述言語:日本語  

  125. X-ray absorption near-edge structures of disordered Mg1-xZnxO solid solutions 査読有り

    T. Mizoguchi, A. Seko, M. Yoshida, H. Yoshida, T. Yoshida, W.Y. Ching and I. Tanaka

    Phys. Rev. B   76 巻   頁: 195125   2007年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    In order to examine x-ray absorption near-edge structures (XANES) of disordered solid solutions of metal oxides, a combined approach of a first principles sipercell method and a cluster expansion method is developed. Zn-L3 edge XANES are measured on a series of Mg1-xZnxO with a rocksalt structure in the range of x = 0.025-0.3 using synchrotron source. A first principles orthogonalized linear combinations of an atomic orbital method is employed to obtain a theoretical spectrum of a given model. A Zn-2p core hole is included in the calculation, and a set of 128 atom supercells is used. Theoretical XANES of disordered solid solutions are obtained as a weighted sum of theoretical spectra for four ordered structures, with the weighting factors determined by the cluster expansion method. The dependence of the spectral shape on the solute concentration is reproduced only when the averaged environment of solute atoms as determined by the solute concentration solution is confirmed by the Monte Carlo calculations.

  126. Depth-Resolved EELS and Chemical State Mapping of N+-Implanted TiO2 Photocatalyst 査読有り

    Tomoko Yoshida, Shunsuke Muto, Jun Wakabayashi

    Mater. Trans.   48 巻   頁: 2580-2584   2007年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We propose novel methods of depth-resolved EELS (DREELS) and chemical state mapping, and the techniques were applied to the cross-sectional TEM (XTEM) sample of N+ implanted TiO2 catalyst. The methods successfully extracted the depth dependence of the N-K ELNES and the spatial distributions of the constituent chemical states separately.

  127. Utilization of gamma-ray irradiation for hydrogen production from water 査読有り

    T.Yoshida, T.Tanabe, N.Sugie and A.Chen

    J. Radioanal. Nucl. Chem   272 巻   頁: 471-476   2007年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  128. XANESによる触媒の状態解析(1) 招待有り 査読有り

    吉田朋子,田中庸裕,巽 一厳,田中 功

    触媒   48 巻   頁: 44-50   2006年

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    担当区分:筆頭著者   記述言語:日本語  

  129. 放射線の有効利用―放射性廃棄物の有効利用を目指して 査読有り

    田辺哲朗,吉田朋子

    日本原子力学会誌   48 巻   頁: 661-668   2006年

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    記述言語:日本語  

  130. XANESによる触媒の状態解析(2) 招待有り 査読有り

    巽 一厳,吉田朋子,田中 功, 田中庸裕

    触媒   48 巻   頁: 264-270   2006年

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    担当区分:筆頭著者   記述言語:日本語  

  131. Temperature dependence of luminescence from a silica glass under in-reactor irradiation 査読有り

    S. Takahara, T. Yoshida, T. Tanabe, M. Okada, Q. Xu

    Nucl. Instr. and Meth. B   250 巻   頁: 377-381   2006年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  132. Spectral restoration and energy resolution improvement of electron-loss spectra by Pixon reconstruction : II. Application to practical ELNES analysis of low SNR 査読有り

    S. Muto, K. Tatsumi, R. C. Puetter, T. Yoshida, Y. Yamamoto and Y. Sasano

    J. Electron Microsc   55 巻   頁: 225-230   2006年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  133. Observation of defect formation process in silica glasses under ion irradiation 査読有り

    M. Watanabe, T Yoshida, T Tanabe, S Muto, A. Inoue, S. Nagata

    Nucl. Instr. and Meth. B   250 巻   頁: 174-177   2006年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  134. Effects of secondary electrons emitted from surroundings on defect formation in silica glass under gamma ray irradiation 査読有り

    S. Obata, T.Yoshida, T.Tanabe, C.Allen, M.Okada, Q. Xu

    Nucl. Instr. and Meth. B   250 巻   頁: 169-173   2006年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  135. Enhanced Gamma-ray Energy Conversion in Water Vessels Part II: Hydrogen Production by Water Radiolysis 査読有り

    T. Yoshida, T. Tanabe, T. Sawasaki and A.Y.K. Chen

    Nucl. Sci. and Eng.   150 巻   頁: 357-361   2005年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    A technique has been proposed to increase the efficiency of hydrogen production from water by γ-ray radiolysis as an effective use of radioactive waste. This is possible by putting special metal structures into water to enhance the conversion of MeV range γ-ray to low-energy electrons which escape from metal into water. The experimental results showed that hydrogen production could be significantly enhanced by carefully controlling the thickness of metal components and the proximity with adjacent metal components.

  136. 高エネルギー放射線の化学反応への応用―γ線を利用した水からの水素製造 招待有り 査読有り

    吉田朋子, 田辺哲朗, アレンチェン

    放射線化学   79 巻   頁: 13-18   2005年

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    担当区分:筆頭著者   記述言語:日本語  

  137. An Attempt to Directly Convert Gamma-ray Energy into Electricity 査読有り

    T. Yoshida , A.Y.K. Chen, J. Nozawa, N. Sugie, and T. Tanabe

    Nucl. Sci. and Eng.   150 巻   頁: 362-367   2005年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    This is a proposal attempting to convert g-ray energy into electric energy via differentiated secondary electron generation by g-ray interacting with two different metal components. In this preliminary study, the maximum generated electric current and power were respectively 0.58 mA and 0.093 mW.

  138. XAFS study on silica glasses irradiated by energy particles 査読有り

    T. Yoshida, T. Tanabe and H. Yoshida

    Phys. Scripta   T115 巻   頁: 435-438   2005年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    X-ray absorption technique was applied to analyze the local structures of fused and synthesized silica glasses before and after the irradiation in a nuclear reactor. Si K-edge EXAFS revealed changes in the SiO4 tetrahedron structure by the irradiation, i.e. a distorted tetrahedron in the silica glass returned to more regular one but the connection between neighboring tetrahedrons became looser.

  139. Decomposition of carbon dioxide by the aid of metals under gamma-ray irradiation 査読有り

    T. Yoshida, T. Tanabe, Y. Okabe, T. Sawasaki and A.Y.K. Chen

    Radiation Research   164 巻   頁: 332-335   2005年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We have proposed a technique to enhance the decomposition of carbon dioxide by gamma-ray irradiation. This is possible by putting metal components into carbon dioxide CO2 gas to promote the conversion of gamma-ray to lower-energy electrons through Compton, photoelectron, and cascading electron knock-on events in metals.

  140. Formation of Nanoarchitectures Including Subnanometer Palladium Clusters and Their Use as Highly Active Catalysts 査読有り

    K. Okamoto, R. Akiyama, H. Yoshida, T. Yoshida and S. Kobayashi

    J. Am. Chem. Soc.   127 巻   頁: 2125-2135   2005年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  141. Enhanced Gamma-ray Energy Conversion in Water Vessels Part I: Physical Mechanisms 査読有り

    A.Y.K. Chen, T. Tanabe, T. Yoshida

    Nucl. Sci. and Eng.   150 巻   頁: 349-356   2005年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  142. Measurement of luminescence from silica glasses : an optical X-ray absorption fine structures study at Si K-edge 査読有り

    T. Yoshida, T. Tanabe, S. Takahara and H. Yoshida

    Phys. Scripta   T115 巻   頁: 528-530   2005年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  143. Temperature dependence of luminescence from silica glasses under in-reactor and 60Co gamma-ray irradiation 査読有り

    S. Takahara, T. Yoshida, T. Tanabe, T. Ii, M. Hirano and M. Okada

    Nucl. Instr. and Meth. B   218 巻   頁: 133-138   2004年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  144. In-Situ Optical Reflection Measurement of a Si(100) Surface under Hydrogen Ion Irradiation 査読有り

    T. Yoshida, M. Sakai and T. Tanabe

    Materials Transactions   45 巻 ( 7 ) 頁: 2018-2022   2004年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  145. Study of damaging process in silica by in-situ hyrogen-induced luminescence measurements 査読有り

    T. Yoshida, T. Tanabe, M. Watanabe, S. Takahara and S. Mizukami

    J. Nucl. Mater.   329-333 巻   頁: 982-987   2004年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  146. FT-IR Study on the effect of OH content on the damage process in silica glasses irradiated by hydrogen 査読有り

    T. Yoshida, T. Tanabe, M. Hirano and S. Muto

    Nucl. Instr. and Meth. B   218 巻   頁: 202-208   2004年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  147. 環境中に放出された人工化学物質の放射線による分解 招待有り 査読有り

    吉田朋子, 田辺哲朗

    応用物理   72 巻   頁: 471-472   2003年

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    担当区分:筆頭著者   記述言語:日本語  

  148. A New Method for the Degradation of Dibutyl Phthalate in Water by Gamma-ray Irradiation 査読有り

    T. Yoshida, T. Tanabe, A. Chen, Y. Miyashita, H. Yoshida, T. Hattori and T. Sawasaki

    Journal of Radioanalytical and Nuclear Chemistry   255 巻   頁: 265-269   2003年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  149. Intermediate Valence State of La0.9Eu0.1Ni2(Si1-xGex)2 Compounds 査読有り

    H. Wada, A. Mitsuda, T. Yoshida, T. Yamamoto and T. Tanaka

    J. Phys. Soc. Jpn   72 巻 ( 10 ) 頁: 2604-2607   2003年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  150. The application of gamma radiolysis of water for H2 production 査読有り

    T. Sawasaki, T. Tanabe, T. Yoshida and R. Ishida

    Journal of Radioanalytical and Nuclear Chemistry   255 巻   頁: 271-274   2003年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  151. In-situ Luminescence Measurement of Silica under Soft X-ray and Gamma-Ray Irradiation 査読有り

    T. Yoshida, T. Tanabe, T. Ii and H. Yoshida

    Nucl. Instr. and Meth. B   191 巻   頁: 382-386   2002年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  152. Active sites on mesoporous and amorphous silica and their photocatalytic activity: Investigations by FTIR, ESR, VUV-UV-vis and photoluminescence spectroscopies 査読有り

    Y. Inaki, H. Yoshida, T. Yoshida, T. Hattori

    J. Phys. Chem. B   106 巻   頁: 9098-9106   2002年

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  153. In-situ luminescence and optical absorption measurements of silica in reactor core 査読有り

    T. Yoshida, T. Ii, T. Tanabe, H. Yoshida and K.Yamaguchi

    J. Nuclear materials   307-311 巻   頁: 1268-1272   2002年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  154. XANES analyses of silicon crystalline irradiated by nitrogen / oxygen ions 査読有り

    T. Yoshida, T. Hara, T. Ii, H. Yoshida and T. Tanabe

    J. Synchrotron Rad.   8 巻   頁: 755-757   2001年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  155. Degradation of Dibuty Phthalate in Water by the Aid of Metals under Gamma-ray Irradiation 査読有り

    T. Yoshida, T. Tanabe, Y. Miyashita, H. Yoshida and T. Hattori

    Chem. Lett.     頁: 876-877   2001年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  156. X-ray absorption and VUV spectroscopic studies of silica glasses irradiated in a nuclear reactor 査読有り

    T. Yoshida, T. Tanabe, H. Yoshida and T. Ii

    J. Electron Spectroscopy and related phenomena   119 巻   頁: 221-227   2001年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  157. Quantification of Aluminium Coordinations in Alumina and Silica-alumina by Al K-edge XANES 査読有り

    Y. Kato, K. Shimizu, N. Matsushita, T. Yoshida, H. Yoshida, A. Satsuma and T. Hattori

    Phys. Chem. Chem. Phys.   3 巻   頁: 1925-1929   2001年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  158. 18pTH-5 RMC-EXELFS法による非晶質・ガラスの構造解析

    武藤 俊介, 吉田 朋子, 田辺 哲朗

    日本物理学会講演概要集   56.2.4 巻 ( 0 ) 頁: 801   2001年

     詳細を見る

    記述言語:日本語   出版者・発行元:一般社団法人 日本物理学会  

    DOI: 10.11316/jpsgaiyo.56.2.4.0_801_3

    CiNii Research

  159. XAFS analysis of europium species supported on aluminium oxide surface 査読有り

    T. Yoshida, T. Tanaka, S. Yoshida, S. Hikita, T. Baba, T. Hinode and Y. Ono

    Applied surface science   156 巻   頁: 65-75   2000年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  160. ガンマ線による環境ホルモンの分解、無害化 査読有り

    吉田朋子、田辺哲朗、宮下祥則、吉田寿雄、服部 忠

    日本原子力学会誌(ショートノート)     頁: 1082-1083   2000年

     詳細を見る

    担当区分:筆頭著者   記述言語:日本語   掲載種別:研究論文(学術雑誌)  

  161. Study on the damaging process of silica by in-reactor-luminescence 査読有り

    T. Ii, T. Yoshida, T. Tanabe, T. Hara, M. Okada and K. Yamaguchi

    J. Nuclear materials   283-287 巻   頁: 898-902   2000年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  162. Hydrogen effect on the surface structure of Si(100) studied by in-situ Raman spectroscopy 査読有り

    T. Hara, T. Yoshida, M. Sakai and T. Tanabe

    Jpn. J. Appl. Phys.   39 巻   頁: 4427-4431   2000年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  163. EXAFS Study of Yb species encapsulated in Potassium Y-type Zeolite 査読有り

    T. Yoshida, T. Tanaka, S. Yoshida, S. Hikita, T. Baba and Y. Ono

    Solid State Commun.   114 巻   頁: 255-259   2000年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  164. In-reactor luminescence from silica glasses 査読有り

    T. Yoshida, T. Tanabe, T. Ii, T. Hara, M. Sakai and Y. Inaki

    Nucl. Instr. and Meth. B   166-167 巻   頁: 476-482   2000年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  165. XAFS study on silica glasses irradiated in a nuclear reactor 査読有り

    T. Yoshida, H. Yoshida, T. Hara, T. Ii, T. Okada and T. Tanabe

    Nucl. Instr. and Meth. B   166-167 巻   頁: 483-489   2000年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  166. XAFS study on D+ irradiated Si surface

    T. Yoshida, H. Yoshida, T. Hara, M. Sakai, A. Omori and T. Tanabe

    J. Synchrotron Rad.   6 巻   頁: 734   1999年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  167. Mg-Al Mixed Oxides as Highly Active Acid-Base Catalysts for Cycloaddition of Carbon Dioxide to Epoxides

    K. Yamaguchi, K. Ebitani, T. Yoshida, H.Yoshida and K. Kaneda

    J. Am. Chem. Soc.   121 巻   頁: 4526   1999年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  168. Application of XANES Spectra to Supported Catalysts 査読有り

    T. Tanaka, T. Yamamoto, Y. Kohno, T. Yoshida and S. Yoshida

    Jpn. J. Appl. Phys.   38 巻   頁: 30-35   1999年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  169. Al K-edge XANES study for the quantification of aluminum coordinations in alumina 査読有り

    K. Shimizu, Y. Kato, T. Yoshida, H. Yoshida, A. Satsuma and T. Hattori

    Chem. Commun.     頁: 1681-1682   1999年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  170. XANES and XPS Analyses of Silicon Irradiated by Deuterium Ions 査読有り

    T. Yoshida, T. Tanabe, H. Yoshida, Y. Yazawa, T. Hara, M. Sakai, H. Yamamoto and Y. Baba

    Jpn. J. Appl. Phys.   38 巻   頁: 305-308   1999年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  171. XAFS Study on the Structure of Ytterbium(III) Trifluoromethanesulfonates as a New Type Catalyst 査読有り

    T. Yoshida, T. Tanaka, T. Yamamoto, S. Yoshida, H. Ishitani and S. Kobayashi

    Jpn. J. Appl. Phys.   38 巻   頁: 59-61   1999年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  172. XAFS study of ytterbium complexes as new type Lewis acid catalysts 査読有り

    T. Yoshida T. Tanaka, T. Yamamoto, S. Yoshida, H. Ishitanic and S. Kobayashi

    J. Synchrotron Rad.   6 巻   頁: 455-457   1999年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  173. Performance of YB66 Soft X-ray Monochromator Crystal at the Wiggler Beam Line of the UVSOR Facility 査読有り

    T. Kinoshita, Y. Takata, T. Matsukawa, H. Aritani, S. Matsuo, T. Yamamoto, M. Takahashi, H. Yoshida, T.Yoshida, Y. Ufuktepe, K. G. Nath, S. Kimura, H. Kumigashira and Y. Kitajima

    J. Synchrotron Rad.   5 巻   頁: 726-728   1998年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  174. Studies of irradiation effects on silica glass by XAFS

    T. Yoshida, H. Yoshida, M. Sakai, T. Hara, T. Okada and T. Tanabe

    Proc. Inter. Conf. of Silica     頁: 557-560   1998年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語  

  175. 軟X線領域X線吸収スペクトル(Soft X-ray XAFS)の固体触媒キャラクタリゼーションへの応用 招待有り 査読有り

    吉田朋子

    触媒学会誌   39 巻   頁: 322-323   1997年

     詳細を見る

    担当区分:筆頭著者   記述言語:日本語  

  176. The state of europium complexes on alumina sarface

    T. Yoshida, T. Tanaka, S. Yoshida, H.Handa, S. Hikita, T. Baba and Y. Ono

    J. Physique IV   7 巻   頁: 915   1997年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  177. Structural analysis of CoO-MgO system by XAFS 査読有り

    T. Yoshida, T. Tanaka, H. Yoshida, T. Funabiki, S. Yoshida and S. Hasegawa

    J. Physique IV   7 巻   頁: 1145-1146   1997年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  178. Epoxidation of Propene by Gaseous Oxygen over Silica and Mg-Loaded Silica under Photoirradiation 査読有り

    H. Yoshida, T. Tanaka, M. Yamamoto, T. Yoshida, T. Funabiki and S. Yoshida

    J. Catal.   171 巻   頁: 351-357   1997年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  179. Mg K-Edge XAFS Study of Silica-Magnesia Systems 査読有り

    H. Yoshida, T. Yoshida, T. Tanaka, T. Funabiki, S. Yoshida, T. Abe, K. Kimura, T. Hattori

    J. Physique IV   7 巻   頁: 911-912   1997年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  180. Study on the Dispersion of Ni ions in NiO-MgO System by X-ray Absorption Fine Structure

    T. Yoshida, T. Tanaka , H. Yoshida, T. Funabiki and S. Yoshida

    Journal of Physical Chemistry   100 巻   頁: 2302   1996年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  181. Control of the structure of niobium oxide species on silica by the equilibrium method 査読有り

    H. Yoshida, T. Tanaka, T. Yoshida, T. Funabiki and S. Yoshida

    Catal. today   28 巻   頁: 79-88   1996年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  182. XAFS Study of Niobium Oxide on Alumina 査読有り

    T. Tanaka, T. Yoshida, H. Yoshida, H. Aritani, T. Funabiki , S. Yoshida, J.M. Jehng and I. E. Wachs

    Catalyst today   28 巻   頁: 71-78   1996年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  183. A XANES Study on the Dehydration Process of Magnesium Hydroxide

    T. Yoshida, T. Tanaka , H. Yoshida, S. Takenaka, T. Funabiki, S. Yoshida and T. Murata

    Physica B   208&209 巻   頁: 581   1995年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  184. XANES study of Eu species encapsulated in potassium Y-type Zeolite

    T. Tanaka, T. Yoshida, S. Yoshida, T. Baba and Y. Ono

    Physica B   208&209 巻   頁: 687   1995年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  185. Study of Dehydration of Magnesium Hydroxide

    T. Yoshida, T. Tanaka , H. Yoshida, T. Funabiki, S. Yoshida and T. Murata

    Journal of Physical Chemistry   99 巻   頁: 10890   1995年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  186. XAFS Study of Niobium Species Formed in the Steps of Preparation of Nb/SiO2 Catalysts by Equilibrium Adsorption Method 査読有り

    H. Yoshida, T. Tanaka, T. Yoshida, T. Funabiki and S. Yoshida

    Physica B   208&209 巻   頁: 681-682   1995年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  187. Catalytic Property of Low-valent Europium Introduced into Y-zeolite 査読有り

    T. Baba, S. Hikita, Y. Ono, T. Yoshida, T. Tanaka and S. Yoshida

    Journal of Molecular Catalysis   98 巻   頁: 49-55   1995年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  188. Valence Variation of Yb Encapsulated in the Super cage of Y-Type Zeolite

    T. Tanaka, T. Hanada (T.Yoshida), S. Yoshida,T. Baba and Y. Ono

    Japanese Journal of Applied Physics   32 巻   頁: 481   1993年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

  189. Physico-chemical and Catalytic Properties of Ytterbium in Y-Zeolite Introduced from the Liquid Ammonia Solution 査読有り

    T. Baba, S. Hikita, R. Koide, Y. Ono, T. Hanada (T. Yoshida), T. Tanaka and S. Yoshida

    Journal of the Chemical Society, Faraday Transactions   89 巻 ( 16 ) 頁: 3177-3180   1993年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  190. Analysis of XANES for identification of highly dispersed transition metal oxide on supports

    S. Yoshida, T. Tanaka, T. Hanada (T. Yoshida), T.Hiraiwa, H. Kanai and T. Funabiki

    Catalysis Letters   12 巻   頁: 277   1992年

     詳細を見る

    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

▼全件表示

書籍等出版物 11

  1. 分析電子顕微鏡(EELS)

    吉田朋子, 山本宗昭( 担当: 共著 ,  範囲: 触媒総合事典 4-25節)

    朝倉書店  2023年2月  ( ISBN:9784254252743

     詳細を見る

    総ページ数:1 online resources (xiv, 530p, 図版 [4] p)   記述言語:日本語

    CiNii Books

  2. 電子顕微鏡(SEM, TEM, STEM)

    田中淳皓, 古南博, 山本宗昭, 吉田朋子( 担当: 共著 ,  範囲: 固体表面キャラクタリゼーション : 機能性材料・ナノマテリアルのためのスペクトロスコピー pp121-135)

    講談社  2022年3月  ( ISBN:9784065261262

     詳細を見る

    総ページ数:x, 293p   記述言語:日本語

    CiNii Books

  3. 人工光合成を促進する半導体光触媒への銀ナノ粒子担持効果

    山本宗昭, 吉田朋子( 担当: 共著 ,  範囲: 金属ナノ粒子、微粒子の合成、調製と最新応用技術 pp530-540)

    技術情報協会  2021年10月  ( ISBN:9784861048623

     詳細を見る

    総ページ数:558p   記述言語:日本語

    CiNii Books

  4. 脱石油に向けたCO[2]資源化技術 : 化学・生物プロセスを中心に = Carbon dioxide capture and utilization by chemical processing and bioprocessing for break away from dependence on oil

    山本宗昭, 赤柄誠人, 吉田朋子( 担当: 共著 ,  範囲: 光触媒表面反応に着目したCO2光還元の高効率化・機能化 pp188-198)

    シーエムシー出版  2020年7月  ( ISBN:9784781315102

     詳細を見る

    総ページ数:x, 375p   記述言語:日本語

    CiNii Books

  5. 黒リンの安全で高収率な溶液合成法

    小澤晃代, 吉田朋子( 担当: 共著 ,  範囲: 機能材料, 40巻 pp.30-38)

    2020年 

  6. XAFSの基礎と応用 = Foundations and applications of XAFS

    吉田朋子( 担当: 共著 ,  範囲: 電子エネルギー損失分光法 pp312-318)

    講談社  2017年7月  ( ISBN:9784061532953

     詳細を見る

    総ページ数:x, 341p   記述言語:日本語

    CiNii Books

  7. 半導体光触媒による二酸化炭素の還元

    山本宗昭, 吉田朋子( 担当: 共著 ,  範囲: 機能材料, 37巻 pp33-39)

    シーエムシー出版  2017年 

  8. 希土類のXANES

    吉田寿雄、吉田朋子( 担当: 共著)

    エヌ・ティー・エス  2008年5月 

     詳細を見る

    記述言語:日本語

  9. 表面・界面工学大系(下巻・応用編)第2編 工業・産業に関する表面・界面技術

    吉田朋子、田中庸裕( 担当: 共著)

    2006年10月 

     詳細を見る

    記述言語:日本語

  10. 固体表面キャラクタリゼーションの実際

    吉田朋子、田中庸裕( 担当: 共著)

    講談社  2005年7月 

     詳細を見る

    記述言語:日本語

  11. L殻吸収端 XANES による機能性表面のキャラクタリゼーション

    吉田朋子、田中庸裕( 担当: 共著)

    化学工学会「表面の機能と応用」研究会編  1994年9月 

     詳細を見る

    記述言語:日本語

▼全件表示

MISC 4

  1. プラズマ照射によるタングステン材料への光触媒機能付与 査読有り

    吉田朋子, 菰口佳吾, 小森勝之, 梶田信, 山本宗昭  

    X線分析の進歩54 巻   頁: 157 - 164   2023年

     詳細を見る

    担当区分:筆頭著者  

  2. EELSによる振動分光測定と材料物性分析 査読有り

    山本宗昭, 吉田朋子  

    ぶんせき9 巻   頁: 368 - 369   2023年

  3. 酸化ガリウム光触媒上に担持された銀ナノ粒子のin-situ UV-Vis拡散反射及びXAFS測定. 査読有り

    山本宗昭, 北島乃樹, 田辺哲朗, 吉田朋子  

    X線分析の進歩54 巻   頁: 165 - 172   2023年

     詳細を見る

    担当区分:責任著者  

  4. タングステン繊維状ナノ構造の光触媒への応用. 査読有り

    吉田朋子  

    プラズマ・核融合学会誌94 巻   頁: 311 - 314   2018年

     詳細を見る

    担当区分:筆頭著者  

講演・口頭発表等 27

  1. X線吸収スペクトル(XAFS)による触媒状態解析

    吉田朋子

    第2回触媒材料研究会 

     詳細を見る

    開催年月日: 2009年11月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  2. XAFSによるナノ構造材料解析

    吉田朋子

    愛知県科学交流財団知的クラスター教育セミナー 

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    開催年月日: 2009年10月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  3. 可視光応答型チタニア光触媒における窒素状態解析

    吉田朋子,武藤俊介,久田江利子

    2009秋 第104回触媒討論会 

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    開催年月日: 2009年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  4. 可視光応答型チタニア光触媒における添加窒素の構造・電子状態解析

    吉田朋子,武藤俊介,久田江利子

    日本金属学会2009年秋期(第145回)講演大会 

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    開催年月日: 2009年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  5. XAFSによる機能元素状態解析

    吉田朋子

    2009年春季第56回応用物理学関係連合講演会シンポジウム講演 

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    開催年月日: 2009年3月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  6. Ge添加シリカガラスの紫外光発光に及ぼすGeクラスターサイズの効果

    吉田 朋子,武藤 俊介, Leny Yuliati, 吉田 寿雄,稲田 康宏

    日本金属学会2009年春期(第144回)講演大会 

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    開催年月日: 2009年3月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  7. X線吸収微細構造(放射光XAFS)

    吉田朋子

    日本金属学会セミナー 

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    開催年月日: 2009年1月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  8. XANESを利用した機能性材料分析(UVSORにおける最近の研究の中から)

    UVSORランチセミナー 

     詳細を見る

    開催年月日: 2008年6月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  9. Clustering of germanium atoms in silica glass responsible for the 3.1 eV emission band studied by optical absorption and X-ray absorption fine structure analysis 国際会議

    T.Yoshida, S. Muto, L. Yuliati, H. Yoshida and Y. Inada

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    開催年月日: 2007年12月

    記述言語:英語   会議種別:ポスター発表  

  10. 量子線と固体との相互作用

    吉田朋子

    原子力研究会 能登原子力センター 

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    開催年月日: 2007年11月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  11. Geイオン注入によるシリカガラスの紫外光領域発光サイトの発現

    吉田朋子、武藤俊介、レニ ユリアティ、吉田寿雄、稲田康宏

    日本金属学会秋期講演会 

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    開催年月日: 2007年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  12. 重なったELNESの成分毎のエネルギーフィルター空間分布像

    吉田朋子、武藤俊介

    日本金属学会秋期講演会 

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    開催年月日: 2007年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  13. 窒素イオン注入チタニア光触媒における活性種構造解析

    吉田朋子、若林 淳、武藤俊介

    日本金属学会春期講演会 

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    開催年月日: 2007年3月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  14. 内殻電子励起によるシリカ照射損傷過程の観察

    吉田 朋子,武藤 俊介,田辺哲朗

    日本金属学会春期講演会 

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    開催年月日: 2007年3月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  15. XANESで何が分かるか

    吉田朋子

    SPring-8講習会「産業利用に役立つXAFSによる先端材料の局所状態解析」 

     詳細を見る

    開催年月日: 2007年2月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  16. Electronic state analysis of implanted nitrogen in visible-light response TiO2 photocatalyst by TEM-EELS 国際会議

    Lattice Defects Forum, The Doyama Symposium on Advanced Materials, “Materials to Save Humankind: The Dream, Creativity, and Working Toward its Realization" 

     詳細を見る

    開催年月日: 2007年

    記述言語:英語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  17. X線吸収スペクトル解析及び測定方法の開発とその応用

    吉田朋子

    京都大学大学院分子工学コロキュウム 

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    開催年月日: 2006年12月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  18. X線吸収スペクトル(XAFS)

    吉田朋子

    近畿化学協会 

     詳細を見る

    開催年月日: 2006年11月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  19. シリカガラスの軟X線照射誘起発光測定

    吉田朋子,武藤俊介,田辺哲朗

    日本原子力学会 

     詳細を見る

    開催年月日: 2006年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  20. X線照射誘起発光を利用したセラミックス中微量成分構造解析の試み

    吉田朋子

    日本金属学会秋期講演会 

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    開催年月日: 2006年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  21. XAFS Study on Microencapsulated Osmium Oxide Catalyst 国際会議

    International Conference on X-ray Absorption Fine Structure 

     詳細を見る

    開催年月日: 2006年7月

    記述言語:英語   会議種別:ポスター発表  

  22. Measurement of soft X-ray excited optical luminescence of a silica glass 国際会議

    International Conference on X-ray Absorption Fine Structure 

     詳細を見る

    開催年月日: 2006年7月

    記述言語:英語   会議種別:ポスター発表  

  23. アルミナの軟X線励起誘起発光

    吉田朋子、小幡祥堂、武藤俊介

    日本放射光学会 

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    開催年月日: 2006年1月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  24. XAFSから得られる情報

    吉田朋子

    近畿化学協会 

     詳細を見る

    開催年月日: 2005年11月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

  25. Utilization of gamma-ray irradiation for hydrogen production from water 国際会議

    Asia-Pacific Symposium on Radiochemistry 

     詳細を見る

    開催年月日: 2005年10月

    記述言語:英語   会議種別:ポスター発表  

  26. Temperature dependence of luminescence from a silica glass under in-reactor irradiation 国際会議

    13th International Conference Radiation Effects in Insulators 

     詳細を見る

    開催年月日: 2005年8月

    記述言語:英語   会議種別:ポスター発表  

  27. 放射線照射下におけるセラミックス材料の観察

    吉田朋子

    日本顕微鏡学会ビーム誘起・励起効果研究部会 

     詳細を見る

    開催年月日: 2005年1月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    国名:日本国  

▼全件表示

科研費 15

  1. プラズマが駆動する気相から種子への活性種輸送の学理構築

    研究課題/研究課題番号:24H02250  2024年4月 - 2029年3月

    日本学術振興会  科学研究費助成事業  学術変革領域研究(A)

    古閑 一憲, 神野 雅文, 朽津 和幸, 吉田 朋子, 谷口 和成, 神野 雅文, 朽津 和幸, 吉田 朋子, 谷口 和成

      詳細を見る

    担当区分:研究分担者 

    プラズマは、環境負荷の少ない植物成長促進法として注目を集めている。中でも種子へのプラズマ照射は、低コストな成長促進法としてだけでなく、DNA修飾変動などを示す。種子へのプラズマ照射効果を明らかにする上で、プラズマから種子にどのような分子がどれほど輸送されたのかを明らかにすることは、必須の検討事項である。本計画研究では、5年間の研究期間において、プラズマから種子、植物細胞への分子輸送機構を明らかにして、輸送制御を実現するために基礎学理を構築する。

  2. 新奇概念(光触媒自身のRedox反応)による高効率二酸化炭素還元触媒の開拓

    研究課題/研究課題番号:23K17850  2023年6月 - 2025年3月

    日本学術振興会  科学研究費助成事業  挑戦的研究(萌芽)

    吉田 朋子, 山本 宗昭, 山本 宗昭

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    担当区分:研究代表者 

    配分額:6370000円 ( 直接経費:4900000円 、 間接経費:1470000円 )

    本研究では,CO2の水による光触媒還元に対して従来考えられてきた反応機構とは全く異なった反応機構を提唱し,それを実証することで,従来の光触媒より格段に活性の高い酸化物光触媒および金属助触媒を探査・開発することに挑戦する.ここで提案する方法では,光による酸化物触媒の還元,または酸化された金属助触媒の光還元が反応律速になっており,従来の半導体光触媒のバンドギャップエネルギーよりも小さいエネルギーの光,即ち,太陽光のほぼ全波長領域を有効利用できる.紫外光しか利用できなかった従来の光触媒反応に比べて,エネルギー利用効率を飛躍的に向上させることが期待される.

  3. 触媒表面機能コア制御による二酸化炭素還元光触媒設計への挑戦

    研究課題/研究課題番号:22H04511  2022年4月 - 2024年3月

    日本学術振興会  科学研究費助成事業  新学術領域研究(研究領域提案型)

    吉田 朋子

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    担当区分:研究代表者 

    配分額:5850000円 ( 直接経費:4500000円 、 間接経費:1350000円 )

    本研究では,二酸化炭素還元反応(人工光合成)を促進するAg助触媒担持Ga2O3(Ag/Ga2O3)光触媒を対象に,Ag助触媒とGa2O3界面に形成される結晶欠陥等の活性サイト(機能コア)の局所構造・電子状態,反応機構に及ぼす効果を解明する.また,この活性サイトを模倣しながらGa2O3表面に特異な結晶欠陥を導入することで,不安定なAg助触媒を担持しなくても二酸化炭素還元を促進する高効率且つ安定な新奇光触媒を構築する.これを実現するための,合理的な触媒設計,活性サイトの可視化,反応基質と活性サイトの動的反応プロセスを観察するための測定システムの構築も目指す.
    有機ナノテンプレートを利用したり,新たに液中プラズマ法を導入することにより1 nm~数十 nmまでの様々なサイズのAgナノ粒子を合成する方法論を確立した.特に液中プラズマ法によるAgナノ粒子の合成においては,液中プラズマ放電システム(石英ガラス製反応容器,金属ロッド電極,パルス発生電源から構成)を新たに構築し,プラズマ放電条件(パルス電圧,パルス幅,周波数)や,水溶液の導電率を制御しながら,電極から銀などの金属ナノ粒子を定常的に生成させるための条件を探索し整理した.有機ナノテンプレートや液中プラズマ法を用いて合成した銀ナノ粒子助触媒を酸化ガリウム上に安定化させた光触媒(Ag/Ga2O3)を調製し,この光触媒を用いて人工光合成反応(二酸化炭素の水による還元反応)を進行させ,CO, H2, O2を生成させることに成功した.また調製した光触媒を高空間分解電子顕微鏡を用いて観察し,Ag粒子,Ag-Ga2O3界面,Ag粒子近傍のGa2O3とサイトごとに明確に区別できることを確認した.
    一方,反応基質(水やCO2分子)と光触媒最表面活性サイト(機能コア)との相互作用を観察するための複合型分光測定システムの設計に着手した.小型の真空チャンバーに試料ホルダー(試料の加熱可能)や真空ポンプを取り付けたものであり,真空排気,反応ガスの導入,光照射といった反応環境の再現が可能であるシステムを構築しつつある.
    液中プラズマ放電システムを用いた金属ナノ粒子の合成は,プラズマ工学分野を中心として,国内外でも進められてきているが,合成した金属ナノ粒子のサイズは放電後のTEM観察などによって初めて明らかになることから,合成中に金属ナノ粒子のサイズを制御することは従来困難であった.
    これに対して本研究では,水中に存在する金属ナノ粒子は,それぞれの化学状態や形状に応じて紫外・可視領域の光を吸収することを利用して,プラズマ放電中に反応容器に外部から紫外・可視光を入射させ,UV-visスペクトルのその場測定を行うことにより,金属ナノ粒子のサイズだけでなく量についても把握できるようにした.具体的には,放電時間に対する吸収波長・強度の変化と,生成した金属ナノ粒子のTEM/XAFS測定による粒子径評価を対応させ,プラズマ放電条件や時間に対する金属ナノ粒子のサイズ・量の変化をin-situ UV-visスペクトルの測定から直接評価し,ナノ粒子合成中に制御した.この試みにより液中プラズマ放電システムを用いた銀などの金属ナノ粒子の合理的な合成が可能になり,順調に研究が進んだものと思われる.
    合成した銀ナノ粒子助触媒を酸化ガリウム上に安定化させた光触媒(Ag/Ga2O3)の調製や,この光触媒を用いた人工光合成反応(二酸化炭素の水による還元反応)については,これまでの触媒調製や反応実験に関するノウハウもあり,経験も豊富であることから,問題なく実施できたと考えられる.
    前年度から引き続き,サイズ制御された金属ナノ粒子助触媒(主に銀ナノ粒子助触媒)の合成と光触媒の調製,人工光合成反応(二酸化炭素の水による還元反応)実験を実施する.また2023年度には,複合型分光測定システムを構築し,これを放射光実験施設のビームラインに取り付ける予定である.このシステムを用いて,Ag/Ga2O3光触媒に反応基質(水やCO2分子)を導入したり光照射をしながら,XAFS測定をし解析することで,反応分子と相互作用する活性サイトを同定する.
    一方,Ga2O3の多形に注目し,異なる結晶構造(α, β, γ, &#603;相など)を,α/β, β/γなど様々な組み合わせで接合する助触媒非担持型光触媒を設計したい.Ag/Ga2O3光触媒の活性サイトの構造・電子状態を模倣するように,Ga2O3中に結晶欠陥を導入することで,水による二酸化炭素還元反応において,高い活性と耐久性を示す新規光触媒の創製を目指す.更にSTEM/EELS分析によって,異なるGa2O3結晶粒の界面に形成された欠陥を可視化したり,反応中の複合的分光測定によって反応に伴う欠陥構造や反応メカニズムの変化を追跡したい.これらの測定分析法を本研究領域において提案される固体材料中の「機能コア」物性分析に応用するだけでなく,材料中の様々な結晶欠陥を応用した新奇熱触媒・光触媒の創製に関する研究へと展開するなど,多くの研究者との共同研究を強力に推進したい.

  4. 液中プラズマを利用した新規触媒調製法の構築と人工光合成触媒の合理的設計

    研究課題/研究課題番号:21K18856  2021年7月 - 2023年3月

    日本学術振興会  科学研究費助成事業  挑戦的研究(萌芽)

    吉田 朋子, 山本 宗昭, 山本 宗昭

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    担当区分:研究代表者 

    配分額:6500000円 ( 直接経費:5000000円 、 間接経費:1500000円 )

    石英ガラス製反応容器,金属ロッド電極,パルス発生電源を用いて,水溶液中でプラズマ放電を可能とする液中プラズマ発生装置を構築し,放電条件(パルス電圧,パルス幅,周波数)を変えることでプラズマ発生状態を制御することが可能になった.電極に銀ロッドを用いてプラズマ放電させながら,水溶液の発光スペクトルを測定した結果,放電中には,電子の他に各種ラジカル(水素,酸素,OHラジカルなど)も生成すること,この生成した電子やラジカル種が銀ロッドに作用することで,水溶液中に銀クラスターや粒子が生成することが明らかとなった.ナノメートルサイズの小さな銀粒子を生成させるための条件を探索した結果,放電条件の他に,水溶液の種類によって銀ナノ粒子のサイズや生成速度が大きく変化することが分かった.
    一方,ナノ粒子のサイズや化学状態を緻密に制御するためには,その生成過程を理解することが不可欠であり,液中プラズマ放電中のin-situ光吸収測定を実施した.即ち,水中に存在するクラスターやナノ粒子は,それぞれの化学状態や形状に応じた波長の光を吸収することを利用して,プラズマ放電中に外部から紫外・可視光を入射させ,マルチチャンネル分光検出器を用いてUV-visスペクトルのその場測定を行い,水溶液中に生成する銀クラスターや銀ナノ粒子にそれぞれ帰属される吸収スペクトルを得ることに成功した.更に,放電時間に対する吸収波長・強度の変化と,TEM測定による銀ナノ粒子物性分析結果を対応させることにより,液中プラズマ放電中に生成する銀クラスターや粒子のサイズや化学状態を直接評価することが可能になった.

  5. 光触媒活性サイトその場分析法開発に関する国際共同研究

    研究課題/研究課題番号:20KK0116  2020年10月 - 2025年3月

    日本学術振興会  科学研究費助成事業  国際共同研究加速基金(国際共同研究強化(B))

    吉田 朋子, 東 正信, 山本 旭, 山本 宗昭, 東 正信, 山本 旭, 山本 宗昭

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    担当区分:研究代表者 

    配分額:18590000円 ( 直接経費:14300000円 、 間接経費:4290000円 )

    2021年度は,アルミナ,シリカ,マグネシア等の各種金属酸化物を対象に,X線で励起した時に放出される紫外・可視光領域の発光(X線励起発光)を検出しながら励起X線のエネルギーを連続的に変化させることによりXAFSスペクトルを得ることを試みた.具体的な例としては,放射光施設においてAl2O3に対してAl K-edge付近のX線を照射したところ,酸素空孔(F+ center)に由来する300nm付近の発光を微弱ながら検出することができた.Al K-edge 前後約50eVの範囲でX線エネルギーを連続的に変化させ,300nm付近の発光強度をモニターすることでスペクトルを描いたところ,従来法(全電子収量法)で測定したAl2O3のAl K-edge XANESスペクトルと同等な微細構造をもつスペクトルが得られていることを見出した.
    一方,今年度は,従来法で測定したXANESスペクトルに対してスペクトルの足し合わせや波形分離を施すことで,様々な局所構造が混在している触媒に対して,同じ元素で構成されていても異なる局所構造を定量的に分析できることを実証した.具体的には,水酸化物を様々な温度で加熱脱水させ,元の水酸化物と脱水により得られる酸化物が様々な割合で混在している状態を作り,これらのXANESスペクトルを従来法(全電子収量法)で測定した.測定されたXANESスペクトルが,水酸化物と酸化物のXANESスペクトルの線形として再現されることや,この方法により水酸化物と酸化物の割合を求められることを示した.一方,多形であるAl2O3の各結晶構造に対してXANESスペクトルを測定し,これらのXANESスペクトルの波形分離をすることによって,各結晶構造に含まれるAlO4とAlO6配位構造を定量的に区別できることも示した.

  6. 固体表面上での動的有機金属化学の展開と環境対応型固体触媒の創成

    研究課題/研究課題番号:17H03458  2017年4月 - 2020年3月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    和田 健司, 馮 旗, 吉田 朋子, 馮 旗, 吉田 朋子

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    担当区分:研究分担者 

    本研究では、固体結晶表面上の有機金属種の動態制御による環境対応型高性能固体触媒を開発した。
    脱水素型ベンゾイミダゾール類合成反応に有効なルチル担持Ir触媒、および水素移動型反応に有効な{010}/{101}面を豊富に有する酸化チタン担体Ir触媒を開発し、担体へのリン修飾の有効性を示した。一方、スチレン類の脱水素シリル化反応に対して、高活性、高選択性を示すイリジウム錯体・酸化セリウム複合触媒を開発した。さらに、炭素-炭素多重結合のヒドロアリール化に対して有効なHCHOおよびPPh3処理Ru/CeO2触媒を見出し、近赤外分光イメージング法による反応生成物の迅速解析の可能性を示した。

  7. 複合アニオン化合物の理解:化学・構造・電子状態解析

    研究課題/研究課題番号:16H06440  2016年6月 - 2021年3月

    日本学術振興会  科学研究費助成事業  新学術領域研究(研究領域提案型)

    林 克郎, 八島 正知, 木本 浩司, 吉田 朋子, 桑原 彰秀, 稲田 幹, 野田 泰斗, 山本 隆文, 設樂 一希, 八島 正知, 木本 浩司, 吉田 朋子, 桑原 彰秀, 稲田 幹, 野田 泰斗, 山本 隆文, 設樂 一希

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    担当区分:研究分担者 

    「複合アニオン化合物」の評価は、従来の研究様式が通用せず、評価・解析手法が全く確立していなかった。このような状況を打破すべく、高度な物質評価法に精通した第一線の研究者が連携し、合成、機能グループと連携した研究を実施した。複合アニオン化合物の評価課題や特徴から、前半では軽元素アニオン識別と構造解析、ヒドリド(H-)イオンの特異性解明、実験および理論の共同による配位多面体幾何の解明に注力した。その後は、複合アニオン系のダイナミクスに着目して、結晶を超えた系、プロセスの解析と理解、新規イオン伝導体の発見と理論解析へと展開した。

  8. 二酸化炭素によるアミンの光触媒的ホルミル化

    研究課題/研究課題番号:16K14477  2016年4月 - 2018年3月

    日本学術振興会  科学研究費助成事業  挑戦的萌芽研究

    吉田 寿雄, 吉田 朋子, 山本 旭, 吉田 朋子, 山本 旭

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    担当区分:研究分担者 

    二酸化炭素の有効利用のために,光触媒を用いて二酸化炭素によるアミン類のホルミル化反応を検討した.金属添加酸化チタン光触媒を用いると,アセトニトリル中でアミン類と二酸化炭素から目的生成物が得られた.この生成物はこの溶媒中でのみ得られ,速度論的検討からアセトニトリルの炭素水素結合の開裂が反応に関与していることが判明した.気相に二酸化炭素がなくても反応は進行したが,気相に二酸化炭素があったほうが生成量は多かった.これらより,アセトニトリルが酸化されて生成したラジカル種が,アミンに相互作用した二酸化炭素と反応し目的生成物が生成する,という反応機構を提案した.

  9. 触媒化学とプラズマ工学融合による広帯域光利用型高機能触媒の創製

    研究課題/研究課題番号:16K14482  2016年4月 - 2018年3月

    日本学術振興会  科学研究費助成事業  挑戦的萌芽研究

    吉田 朋子, 梶田 信, 梶田 信

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    担当区分:研究代表者 

    配分額:3640000円 ( 直接経費:2800000円 、 間接経費:840000円 )

    Heプラズマ照射によりW板表面に生成した樹枝状ナノ構造を酸化処理することによって,WO3/W複合材料を作製し,この材料が近赤外光照射下でメチレンブルー(MB)脱色反応を進行させることを見出した.MBが光触媒的に分解されていることを確認するために,この材料を入れたMB水溶液に近赤外光を照射しながらXANESを測定した.光照射によってMB分子のπ*(S-C)と *(S-C)結合に由来するピークが減少し,SO42-に帰属されるピークが現れたことから,MB分子中のS-C結合が切れ,最終的にSO42-になること,即ち,実際に光触媒反応によるMB分子の分解は進行していることを実証することができた

  10. 光触媒表面反応に着目した人工光合成システムの合理的設計

    研究課題/研究課題番号:15H00871  2015年4月 - 2017年3月

    日本学術振興会  科学研究費助成事業  新学術領域研究(研究領域提案型)

    吉田 朋子

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    担当区分:研究代表者 

    配分額:3640000円 ( 直接経費:2800000円 、 間接経費:840000円 )

    銀担持量の異なる銀担持酸化ガリウム光触媒(Ag/Ga2O3)を調製し,水を電子源とした二酸化炭素還元反応を行ったところ,0.1 wt% Ag/Ga2O3触媒を用いた時のCO生成速度はGa2O3触媒に比べて十数倍大きくなったが,1.0 wt% まで銀担持量を増加させると0.1 wt%担持した場合と比べて約半分までCO生成速度が小さくなった.また両触媒についてTEM観察を行った結果,0.1 wt% Ag/Ga2O3触媒中には1 nm程度のAgクラスターが主に存在しており,1.0 wt% Ag/Ga2O3触媒中では主に2 ~ 10 nmのAg粒子が多数存在していることが明らかとなった.
    Ag L3-edge XANES及びAg K-edge EXAFS解析の結果,1 nm程度のAgクラスターは,Ag-Ag結合距離がバルクAgのものと同等であることから金属種であることが分かり,更に担体との相互作用によってAg 4d軌道の電子密度がバルクAgよりも増加していることが示唆された.1.0 wt% Ag/Ga2O3触媒中の2 ~ 10 nm 程度のAg粒子については2種類のAg-Ag対が認められ,その原子間距離からAg金属粒子とAgGaO2のような複合酸化物種が混在していることが分かった.
    これらの結果を反応中におけるin-situ FT-IR測定結果と比較したところ,特に複合酸化物種はCO2の吸着サイトを増加させるものの,反応中間体bidentate-formateの生成には寄与しないのに対し,担体との相互作用の強い小さなAgクラスターはbidentate-formate生成を促進し,CO生成量を増加させることが明らかとなった.
    一方、銀助触媒の新奇な調製法として銀電極を水中で放電させることによってナノ粒子を合成する手法(液中プラズマ法)の構築を目指した.プラズマ放電条件,水に加える電解質の種類・濃度,水温によって,銀ナノ粒子のサイズを変えられることが分かり,実際に合成した銀ナノ粒子を助触媒として用いることができた.

  11. 硫黄被毒したナノ粒子の水素吸放出特性のがん検知への応用

    研究課題/研究課題番号:26289255  2014年4月 - 2017年3月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    八木 伸也, 吉田 朋子, 吉田 朋子

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    担当区分:研究分担者 

    ガス中蒸発法によりRhおよびPdのナノ粒子作製を行った。Rh、Pdナノ粒子は概ね1-4 nmの粒子径であることがわかった。Rhナノ粒子表面に吸着した硫黄を含む分子(主としてチオール系分子)は、化学吸着するがそれ以上の解離反応を示さない結果であったが、水素吸放出に関しては水素吸放出反応をほとんど示さないことがわかった。一方、Pdナノ粒子については、Pdナノ粒子表面を予め硫黄原子で被毒した後に水素吸放出反応を調べたところ、水素吸放出反応速度が著しく鈍化することがわかった。この結果を受け、今後はガン・スクリーニングへの応用を継続することを予定している。

  12. 太陽光とメタンを用いた水素製造のための高品質微結晶光触媒の高度精密設計

    研究課題/研究課題番号:25289285  2013年4月 - 2016年3月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    吉田 寿雄, 吉田 朋子, 吉田 朋子

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    担当区分:連携研究者 

    太陽光を用いて,常温でメタンと水から水素を取り出す光触媒反応(常温メタン水蒸気反応)のための高活性な光触媒の開発するために,高品質な結晶からなる光触媒の開発を試みた.結晶を得られやすい方法として知られる溶融塩法を採用し,チタン酸塩やタンタル酸塩の微結晶を合成し,助触媒として白金を添加して光触媒を調製し,光触媒の構造と光触媒活性との相関を検討した.その結果,従来の固相反応法によるものよりも高活性な光触媒を得ることに成功した.また,多結晶体を構成する最小単位の単結晶である結晶子が大きな方がより高活性であるという相関関係を見出し,今後の光触媒を設計するうえでの大きな指針を得ることに成功した.

  13. 超高活性触媒設計のための触媒活性種特異的サイト選択的構造・電子状態解析の実現

    研究課題/研究課題番号:24360332  2012年4月 - 2016年3月

    日本学術振興会  科学研究費助成事業  基盤研究(B)

    吉田 朋子

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    担当区分:研究代表者 

    配分額:18980000円 ( 直接経費:14600000円 、 間接経費:4380000円 )

    本研究では,X線誘起発光を利用したサイト選択的X線吸収スペクトル(XAFS)測定法を構築し,これを用いて固体中の欠陥や発光サイト局所構造を対象としたXAFS測定を行った.一方,XAFSと電子分光法(EELS, EFTEM)を組み合わせ,更に統計学的数値処理を援用することによって,固体触媒中の異なる化学状態を区別した定量的分析や可視化(マッピング)が可能となった.この手法を窒素添加チタニア触媒に応用し,その可視光応答発現メカニズムについて考察した.

  14. プラズマ照射が拓く新奇太陽光応答型光触媒の開発

    研究課題/研究課題番号:24656489  2012年4月 - 2015年3月

    日本学術振興会  科学研究費助成事業  挑戦的萌芽研究

    吉田 朋子

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    担当区分:研究代表者 

    配分額:4030000円 ( 直接経費:3100000円 、 間接経費:930000円 )

    W板へのHeプラズマ照射により樹枝状ナノ構造体を作製した。この試料を部分酸化して得られたWO3/Wは、1~5 eVの広波長領域の光を吸収することを見出した。この材料は、WO3のバンドギャップよりもエネルギーの低い近赤外光照射下においてもメチレンブルー脱色反応を進行させ、その反応速度は材料の表面酸化割合で変化することが明らかとなった。しかし、反応中の分解生成物の吸着によって表面に存在していたW(0)種が酸化されることによって反応速度が低下することも分かった。

  15. 光触媒による炭素-炭素結合形成を伴う高選択的芳香環官能基化反応

    研究課題/研究課題番号:24656490  2012年4月 - 2014年3月

    日本学術振興会  科学研究費助成事業  挑戦的萌芽研究

    吉田 寿雄, 熊谷 純, 吉田 朋子, 熊谷 純, 吉田 朋子

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    担当区分:連携研究者 

    芳香環の官能基化は,高温高圧下で反応性の高い化学物質を用いた多段階反応により,多量の副生成物を伴いおこなわれていることが多く,より温和な条件と単純な反応経路で無駄の少ない環境に優しい反応プロセスへの変換が切望されている.本研究では,ベンゼンとアセトニトリルからシアン化ベンゼンと水素を直接得るという革新的な炭素-炭素結合形成を伴う高選択的芳香環官能基化反応(シアノメチル化)に成功した.さらに,その反応機構を詳細に調べたところ,ここで用いたパラジウム添加酸化チタン光触媒では,パラジウムが光触媒の助触媒としての機能だけではなく芳香環の活性化に直接関与している,ハイブリッド触媒であることがわかった.

▼全件表示

産業財産権 15

  1. 黒リン含有組成物の製造方法及び黒リン含有組成物

    小澤晃代, 国吉幸浩, 吉田朋子

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    出願番号:特願2019-120261  出願日:2019年6月

    公開番号:特開2021-4161  公開日:2021年1月

    特許番号/登録番号:特許第7248242号  登録日:2023年3月 

  2. Method for generating electric power and electric battery

     詳細を見る

    出願番号:10/924,877  出願日:2004年8月

    公開番号:US2005/0077876 A1 

    特許番号/登録番号:U.S. Patent No. 7028477 B2  登録日:2006年4月 

    出願国:外国  

  3. 発電方法及び電池

    法人名大

     詳細を見る

    出願日:2004年8月

    公開番号:US-2005-0077876-A1  公開日:2005年4月

    特許番号/登録番号:US 7,028,477 B2 

    出願国:外国   取得国:外国

  4. 有機化合物の分解方法

    吉田朋子, 田辺哲朗, 吉田寿雄,服部 忠

     詳細を見る

    出願番号:特願2004-78398  出願日:2004年3月

    公開番号:特開2004-209476 

    登録日:2004年7月 

    出願国:国内  

  5. 有機化合物の分解方法

    法人名大

     詳細を見る

    出願日:2004年3月

    公開番号:2004-209476  公開日:2004年7月

    特許番号/登録番号:04178245 

    出願国:国内   取得国:国内

  6. Method for generating electric power and electric battery

     詳細を見る

    出願番号:10/727,557  出願日:2003年12月

    公開番号:US2004/0163942 A1 

    登録日:2004年8月 

    出願国:外国  

  7. 発電方法及び電池

    法人名大

     詳細を見る

    出願日:2003年12月

    公開番号:US 2004-0163942 A1  公開日:2004年8月

    出願国:外国   取得国:外国

  8. 発電方法及び電池

    吉田朋子, 田辺哲朗, アレンチェン

     詳細を見る

    出願番号:特願2003-312863  出願日:2003年9月

    公開番号:特開2005-83756 

    特許番号/登録番号:特許第3861154号  登録日:2006年10月 

    出願国:国内  

  9. 発電方法及び電池

    東海国立大学機構

     詳細を見る

    出願日:2003年9月

    公開番号:2005-083756  公開日:2005年3月

    特許番号/登録番号:03861154 

    出願国:国内   取得国:国内

  10. 発電方法及び電池

    吉田朋子, 田辺哲朗

     詳細を見る

    出願番号:特願2002-362541  出願日:2002年12月

    公開番号:特開2004-191315 

    特許番号/登録番号:特許第3837528号  登録日:2006年8月 

    出願国:国内  

  11. 発電方法及び電池

    東海国立大学機構

     詳細を見る

    出願日:2002年12月

    公開番号:2004-191315  公開日:2004年7月

    特許番号/登録番号:03837528 

    出願国:国内   取得国:国内

  12. 水素製造方法

    吉田朋子, 田辺哲朗

     詳細を見る

    出願番号:特願2001-152599  出願日:2001年5月

    公開番号:特開2002-338201 

    出願国:国内  

  13. 水素製造方法

    法人名大

     詳細を見る

    出願日:2001年5月

    公開番号:2002-338201  公開日:2002年11月

    出願国:国内   取得国:国内

  14. 有機化合物の分解方法

    吉田朋子, 田辺哲朗, 吉田寿雄,服部 忠

     詳細を見る

    出願人:吉田朋子, 田辺哲朗, 吉田寿雄,服部 忠

    出願番号:2000-155089  出願日:2000年5月

    公開番号:2001-334262 

    特許番号/登録番号:第3564532号  登録日:2004年6月 

    出願国:国内  

  15. 有機化合物の分解方法

    法人名大

     詳細を見る

    出願日:2000年5月

    公開番号:2001-334262  公開日:2001年12月

    特許番号/登録番号:03564532 

    出願国:国内   取得国:国内

▼全件表示

 

担当経験のある科目 (本学) 1

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    2004

担当経験のある科目 (本学以外) 1

  1. 集中講義

    2007年4月 - 2008年3月 九州大学)

 

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    役割:審査・評価

    2023年10月 - 現在

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    種別:審査・学術的助言 

  2. 日本MRS水素科学技術連携研究会理事

    役割:企画立案・運営等

    2022年4月 - 現在

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    種別:学会・研究会等 

  3. 触媒学会理事(教育委員会委員長)

    役割:企画立案・運営等

    2022年4月 - 2024年3月

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    種別:学会・研究会等 

  4. 文部科学省核融合技術委員会委員

    役割:審査・評価

    2021年4月 - 現在

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    種別:審査・学術的助言 

  5. 日本分析化学会近畿支部役員

    役割:企画立案・運営等

    2015年4月 - 2024年3月

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    種別:学会・研究会等 

  6. 触媒学会西日本支部東海北陸地区代議員

    役割:企画立案・運営等

    2014年4月 - 2015年3月

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    種別:学会・研究会等 

  7. 日本金属学会金属組織写真賞委員

    役割:審査・評価

    2010年1月 - 2014年12月

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    種別:学会・研究会等 

  8. 日本分析化学会X線分析研究懇談会運営委員

    役割:企画立案・運営等

    2009年4月 - 現在

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    種別:学会・研究会等 

  9. 日本金属学会男女共同参画委員会委員

    役割:企画立案・運営等

    2009年4月 - 2012年3月

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    種別:学会・研究会等 

  10. 伊方原子力発電所環境安全管理委員会委員

    役割:審査・評価

    2008年1月 - 2012年12月

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    種別:学術調査 

  11. 日本原子力学会「核燃料サイクルの物質利用」研究専門委員会幹事

    役割:企画立案・運営等

    2005年10月 - 2015年3月

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    種別:学会・研究会等 

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