2023/04/17 更新

写真a

オガワ サトシ
小川 智史
OGAWA Satoshi
所属
大学院工学研究科 エネルギー理工学専攻 エネルギー材料工学 助教
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
助教
連絡先
メールアドレス

学位 1

  1. 博士(工学) ( 2014年4月   名古屋大学 ) 

研究キーワード 8

  1. ナノ粒子

  2. 水素吸蔵材料

  3. XPS

  4. ナノ粒子

  5. 水素吸蔵材料

  6. X線光電子分光(XPS)

  7. X線吸収微細構造 (XAFS)

  8. XAFS

研究分野 2

  1. ナノテク・材料 / 応用物理一般  / X線分光分析

  2. ナノテク・材料 / ナノ構造物理  / ナノ粒子

現在の研究課題とSDGs 1

  1. 水素吸蔵ナノ材料の創製とその評価

経歴 4

  1. 名古屋大学   大学院工学研究科 エネルギー理工学専攻 エネルギー材料工学   助教

    2017年4月 - 現在

  2. 名古屋大学   大学院工学研究科 マテリアル理工学専攻 量子エネルギーシステム工学   助教

    2014年4月 - 2017年3月

  3. 学術振興会特別研究員

    2011年4月 - 2014年3月

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    国名:日本国

  4. 学術振興会特別研究員

    2011年4月 - 2014年3月

学歴 5

  1. 名古屋大学   工学研究科   量子工学専攻

    2009年4月 - 2014年3月

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    国名: 日本国

  2. 名古屋大学   工学研究科   量子工学専攻

    2011年4月 - 2014年3月

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    国名: 日本国

  3. 名古屋大学   工学研究科   量子工学専攻

    2011年4月 - 2014年3月

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    国名: 日本国

  4. 名古屋大学   工学部   物理工学科量子エネルギー工学コース

    2005年4月 - 2009年3月

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    国名: 日本国

  5. 名古屋大学   工学部   物理工学科量子エネルギー工学コース

    2005年4月 - 2009年3月

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    国名: 日本国

所属学協会 3

  1. 公益財団法人日本金属学会   会員

    2016年9月 - 現在

  2. 日本放射光学会   会員

    2014年10月 - 現在

  3. 日本XAFS研究会   会員

    2009年9月 - 現在

委員歴 1

  1. 日本XAFS研究会   企画幹事  

    2020年1月 - 2021年12月   

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    団体区分:学協会

受賞 1

  1. Student Award

    2013年12月   9th International Symposium on Atomic Level Characterization for New Materials and Devices '13   XAFS and XPS study of hydro-/dehydrogenation reaction of Mg-Pd nanoparticles

    Satoshi Ogawa

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    受賞区分:国際学会・会議・シンポジウム等の賞 

 

論文 40

  1. Analysis of phase transformation in Mg2NiH4 via in situ synchrotron X- ray measurements

    Towata Shin-ichi, Noritake Tatsuo, Ogawa Satoshi, Nakanishi Yuuki, Sakuma Yasuhiro, Tachiki Shoji, Hirotomo Toshiki, Suda Kohei

    JOURNAL OF ALLOYS AND COMPOUNDS   938 巻   2023年3月

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    出版者・発行元:Journal of Alloys and Compounds  

    Mg-based alloys such as Mg2NiH4 are still attracting attention as high-capacity hydrogen storage materials. Mg2NiH4 undergoes the phase transformation between low-temperature (LT) and high temperature (HT) phases near the hydrogen desorption temperature. Herein, the crystallographic changes of Mg2NiH4 were investigated to clarify the behavior of the phase transformation by in situ synchrotron radiation X-ray measurements. The samples with three thermal histories (slow cooling, quenching from the HT phase, and hydrogenation below the transformation temperature) were prepared. These thermal histories affected the ratio of the LT phase without microtwinning (LT1) and with microtwinning (LT2). As the LT2/LT1 ratio increases, the phase transformation temperature decreases, and the phase transformation accelerates. X-ray diffraction peak analyses showed that the crystallite size and the lattice strain depend on the thermal history of the sample. X-ray absorption spectra indicated an increase in the short-range disorder of Mg2NiH4 when hydrogenated below the transformation temperature, which causes anomalous phase transformation and modulates the transformation temperature.

    DOI: 10.1016/j.jallcom.2022.168594

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  2. Sulfur in humin as a redox-active element for extracellular electron transfer

    Pham Duyen Minh, Oji Hiroshi, Yagi Shinya, Ogawa Satoshi, Katayama Arata

    GEODERMA   408 巻   2022年2月

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    記述言語:日本語   出版者・発行元:Geoderma  

    Humin (HM), an insoluble humic substance that occurs as an organo-mineral complex, mediates extracellular electron transfer (EET) among microorganisms in the geosphere. Although sulfur (S)-containing functional groups have been posited as possible redox-active groups in HM, there has been no direct evidence in this regard. Here, we characterized the redox-active S in HM from different natural sources using synchrotron radiation-based X-ray absorption spectroscopy in partial fluorescence yield mode. The S content in HM is less than 0.9%, with the oxidation states ranged widely from −2 to +6. About 9% to 19% of total S in HM was redox variable, corresponding to 1.2 × 10−5 to 17.1 × 10−5 Eq/g-HM redox capacity. The redox capacity of HM driven by S is comparable to or larger than the electron donating capacity of HM observed in anaerobic microbial dechlorination of pentachlorophenol, suggesting that S is one of the significant redox-active elements in HM. These findings provide new insights into the role of S cycling in biogeochemical processes and microbial energy networks.

    DOI: 10.1016/j.geoderma.2021.115580

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  3. Effects of the amount of Au nanoparticles on the visible light response of TiO2 photocatalysts

    Yoshida Tomoko, Misu Yuhei, Yamamoto Muneaki, Tanabe Tetsuo, Kumagai Jun, Ogawa Satoshi, Yagi Shinya

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

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    記述言語:日本語   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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  4. Comparison of platinum photodeposition processes on two types of titanium dioxide photocatalysts

    Yamamoto Muneaki, Minoura Yasuhiro, Akatsuka Masato, Ogawa Satoshi, Yagi Shinya, Yamamoto Akira, Yoshida Hisao, Yoshida Tomoko

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

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    記述言語:日本語   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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  5. Characterization by Synchrotron-Radiation X-Ray Photoelectron Spectroscopy of NO Adsorption on Rh (vol 16, pg 36, 2018)

    Koda Yuki, Sumida Hirosuke, Ogawa Satoshi, Tsukada Chie, Namatame Hirofumi

    E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY   17 巻   頁: 69 - 70   2019年7月

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    記述言語:日本語   出版者・発行元:e-Journal of Surface Science and Nanotechnology  

    Figures 3 and 4 in the original article [1] were inappropriately displayed. Correct figures are shown below. “Table 1” and “Table 3” that appear in the text on p. 39 in Ref. 1 should be replaced by “Table I” and “Table III”, respectively. The publisher found that they occurred during the production process. None of the corrections change any discussion and conclusions of the article. (Figure Presented).

    DOI: 10.1380/ejssnt.2019.69

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  6. Development of sample preparation technique to characterize chemical structure of humin by synchrotron-radiation-based X-ray photoelectron spectroscopy

    Duyen Minh Pham, Miyata Yasushi, Awata Takanori, Nakatake Masashi, Zhang Chung Fang, Kanda Keiji, Ogawa Satoshi, Ohta Shozo, Yagi Shinya, Katayama Arata

    SURFACE AND INTERFACE ANALYSIS   51 巻 ( 2 ) 頁: 226 - 233   2019年2月

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    記述言語:日本語   出版者・発行元:Surface and Interface Analysis  

    Carbon-binding state of humin (HM, a non-conductive insoluble organo-mineral humic substance) was successfully characterized for the first time by synchrotron-radiation–based X-ray photoelectron spectroscopy (XPS). Four sample preparation techniques—HM on double-sided carbon tape, indium sheet, copper mesh, and in pellet formed from the mixture of HM and copper powder (Cu) at different mixing ratios (1:1, 1:2, and 1:6 v/v)—were compared. The results show that HM samples prepared using the first three methods had significant charge buildup, which made the interpretation of the XPS spectra impossible because of the shifts in the binding energy of C 1s XPS spectra. Pellets of HM:Cu mixture enhanced the electrical conductivity and reduced charge buildup on the sample surface. Pellets prepared with HM:Cu ratio of 1:1 (v/v) provided the minimum charge buildup and high sensitivity with difference in C 1s spectra regardless of the observing position. The C 1s spectra, estimated by the subtraction of the carbon contamination in Cu, showed the resolution of CC (284.0 eV), CC/CH (285.1 eV), CO (286.3 eV), CO (287.3 eV), and OCO (288.3 eV) and three additional peaks of CF (289.3 eV), CF2 (290.2 eV), and CF3 (291.4 eV). Soft X-ray absorption spectroscopic (XAS) analysis further proved the existence of fluoride (F 1s) in HM structure. The detection of fluorinated carbon in HM showed a great advancement of XPS compared with other conventional analyses. X-ray with the incident angle of 0° provided the smallest (nearly negligible) energy shift in the C 1s spectra of HM and did not damage the surface of the sample.

    DOI: 10.1002/sia.6574

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  7. Surface chemical states of gold nanoparticles prepared using the solution-plasma method in a CsCl aqueous solution

    Tsukada Chie, Yoshida Hikaru, Ogawa Satoshi, Yoshigoe Akitaka, Yagi Shinya, Yaita Tsuyoshi

    SURFACE AND INTERFACE ANALYSIS   51 巻 ( 1 ) 頁: 85 - 88   2019年1月

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    記述言語:日本語   出版者・発行元:Surface and Interface Analysis  

    In this study, gold nanoparticles (AuNPs) prepared in a 5 mM CsCl aqueous solution using the solution-plasma method are characterized via transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy with synchrotron radiation (SR-XPS). The particle diameter is measured over the process time via TEM. During the solution-plasma process, small particles of 2.1 to 2.2-nm diameter are generated in the CsCl aqueous solution; these particles then enlarge via Ostwald ripening over time until they reach an equilibrium size of ~13 nm after 36 days. In addition, the surface chemical states of the AuNPs are characterized at different depths via SR-XPS. The SR-XPS measurements obtained using incident X-ray energy (hν) of 945.0 eV revealed that Cs─Au, Cl─Au, and Cs─Cl─Au bonds are present 1.2 nm below the surface. The measurements obtained at an incident X-ray energy of 2515.0 eV showed that Cs─Cl─Au bonding is also present 2.5 nm below the surface, indicating that Cs and Cl strongly interact with Au. The TEM and SR-XPS measurements revealed that 2 processes occur cyclically during the growth process via Ostwald ripening: (i) the Cs and Cl in the aqueous solution adsorb on the AuNP surface and (ii) Au atoms subsequently bond to the AuNPs surface.

    DOI: 10.1002/sia.6555

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  8. Au nanorods fabricated by means of solution plasma method

    Tsukada Chie, Mizutani Tsuyoshi, Ogawa Satoshi, Nameki Hirofumi, Yagi Shinya

    SURFACE AND INTERFACE ANALYSIS   48 巻 ( 11 ) 頁: 1248 - 1251   2016年11月

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    記述言語:日本語   出版者・発行元:Surface and Interface Analysis  

    Au nanorods with a low toxicity are important in medical field. The nanorods are generally fabricated by using cetyltrimethylammonium bromide (CTAB), which has a high toxicity. We have attempted the fabrication of Au nanorods without CTAB reagent. In this study, Au nanoparticles as growth seeds of the nanorods have been fabricated by using Au rods and NaCl aqueous solution. Subsequently, Au3+ ions of HAuCl4 have been reduced in the mixing solution, which includes the Au nanoparticles and the NaCl aqueous solution, by means of the solution plasma between W rods. The amount of Au3+ ion has been directly monitored during the solution plasma process by using in-situ UV–Vis-NIR. The fabricated solution possesses the Au nanoparticles of shapes of rod, sphere, triangle plate and hexagonal plate, respectively. The Au nanorods may be fabricated by both aggregating the reduced Au3+ ion at the surfaces of the Au nanoparticles as the growth seeds and controlling the growth orientation of the Au nanorods by the adsorption of Cl− ions on Au{100} facets. To control the narrow dispersion relation between the short and the long axes lengths of the Au nanorods, the addition of HAuCl4 aqueous solution in small volume steps is a key point. Copyright © 2016 John Wiley & Sons, Ltd.

    DOI: 10.1002/sia.6096

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  9. 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   頁: 150 - 153   2016年5月

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    出版者・発行元:e-Journal of Surface Science and Nanotechnology  

    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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  10. XAFS analysis for quantification of the gallium coordinations in Al2O3-supported Ga2O3 photocatalysts

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

    16TH INTERNATIONAL CONFERENCE ON X-RAY ABSORPTION FINE STRUCTURE (XAFS16)   712 巻 ( 1 )   2016年

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    記述言語:日本語   出版者・発行元:Journal of Physics: Conference Series  

    Ga2O3 loaded Al2O3 samples (Ga2O3/Al2O3) were prepared to change coordination structures around Ga atoms. Ga K-edge XANES spectra of the Ga2O3/Al2O3 samples showed two peaks assigned to Ga atoms having tetrahedral coordination structure (Ga(t)) and octahedral one (Ga(o)). Curve-fitting analysis of XANES spectra was carried out with a set of pseudo- Voight and arctangent functions, and the fractions of Ga(t) and Ga(o) were quantitatively estimated from the ratio of the peak areas. EXAFS curve-fitting analysis also evaluated the fractions of Ga(t) and Ga(o) and they were in good agreement with those obtained by XANES analysis. It was revealed that the fraction of Ga(t) increased with the decrease in the loading amount of Ga2O3 due to the interaction of Ga species with Al2O3. The fractions of Ga(t) and Ga(o) might relate to the photocatalytic activity for CO2 reduction with H2O over the Ga2O3/Al2O3 samples.

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

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  11. Characterization of nitrogen ion implanted TiO2 photocatalysts by XAFS and XPS

    Yoshida Tomoko, Niimi Satoshi, Yamamoto Muneaki, Ogawa Satoshi, Nomoto Toyokazu, Yagi Shinya

    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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    記述言語:日本語   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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  12. In situ UV-vis investigation of growth of gold nanoparticles prepared by solution plasma sputtering in NaCl solution

    Mizutani Tsuyoshi, Ogawa Satoshi, Murai Takaaki, Nameki Hirofumi, Yoshida Tomoko, Yagi Shinya

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

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    記述言語:日本語   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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  13. 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   頁: 343 - 346   2015年6月

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    出版者・発行元:e-Journal of Surface Science and Nanotechnology  

    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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  14. Vulcanization reaction of squalene and S-8 powder studied by Sulfur K-edge NEXAFS under liquid phase

    Yagi S., Menjo Y., Tsukada C., Ogawa S., Kutluk G., Namatame H., Taniguchi M.

    INTERNATIONAL CONFERENCE ON SOLID FILMS AND SURFACES (ICSFS 2014)   76 巻 ( 1 )   2015年

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    記述言語:日本語   出版者・発行元:IOP Conference Series: Materials Science and Engineering  

    Vulcanized rubber materials are useful in our surroundings. However, detail structure and reaction are not revealed even in present. Since squalene molecule possesses some same properties compared with natural rubber, we have prepared the samples of vulcanized squalene at 140 ° C for several hours. To understand the vulcanization reaction,sulfur K-edge NEXAFS measurements have been carried out for the vulcanized squalene under liquid phase with He-path system and fluorescence detection mode. Moreover, we have tried curve fitting analysis of NEXAFS spectra. The results indicate that the squalene has been vulcanized by the S8 molecule at 140 ° C and the S8 molecule length is shortened from 8 to 5-6 after the vulcanization reaction.

    DOI: 10.1088/1757-899X/76/1/012004

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  15. Spectroscopic and morphological studies on interaction between gold nanoparticle and liposome constructed with phosphatidylcholine

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

    INTERNATIONAL CONFERENCE ON SOLID FILMS AND SURFACES (ICSFS 2014)   76 巻 ( 1 )   2015年

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    記述言語:日本語   出版者・発行元:IOP Conference Series: Materials Science and Engineering  

    The gold nanoparticles (Au NPs) colloidal solution and the phosphatidylcholine (PC) liposome aqueous solution are fabricated by the solution plasma method and the extrusion procedure, respectively. When the Au NPs colloidal solution and the PC liposome aqueous solution are mixed, considering the TEM image, we think that the Au NPs firstly are covered with the PC molecules, which do not contribute to form the PC liposome, and subsequently the Au NPs covered with the PC adsorb on the PC liposome surface. We propose that the PC molecule adsorbs on the Au sheet surface at the methyl group of N-CH3 and the oxygen atoms of P-O, P=O, C-O and C=O bonds, because each peak intensity of N, O and P K-edges NEXAFS spectra for the PC/Au sheet is reduced in comparison with that for the PC multilayer. Furthermore, the Au NPs covered with PC seem to be aggregated each other through the hydrophobic groups of PC on Au NPs.

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

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  16. Hydrogen storage property of Ni nanoparticles fabricated by the gas evaporation method

    Fujimoto Taishi, Ogawa Satoshi, Yoshida Tomoko, Uchiyama Naoki, Yagi Shinya

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

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    記述言語:日本語   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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  17. The inuence of the preparing method of a Ag/Ga<inf>2</inf>O<inf>3</inf> catalyst on its activity for photocatalytic reduction of CO<inf>2</inf> 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   頁: 263 - 268   2014年6月

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    出版者・発行元:e-Journal of Surface Science and Nanotechnology  

    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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  18. 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

  19. 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

     詳細を見る

    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.

    Scopus

  20. Spectral studies on sulfur poisoning of Pd/Mg6Ni by NEXAFS and XPS

    Yagi S., Nambu M., Tsukada C., Ogawa S., Kutluk G., Namatame H., Taniguchi M.

    APPLIED SURFACE SCIENCE   267 巻   頁: 45 - 47   2013年2月

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    記述言語:日本語   出版者・発行元:Applied Surface Science  

    We have studied on the hydrogen storage materials based on Mg-Ni alloy and fabricated the sample constructed with the Pd thin layer (TL) on Mg 6 Ni alloy substrate. The adsorption behavior of the dimethyl disulfide (DMS) molecules on the sample has been measured to reveal the sulfur poisoning of the Pd TL/Mg 6 Ni by means of XPS and Sulfur K-edge NEXAFS techniques. The chemisorbed DMS, methanethiolate (MT) and atomic S have been observed on the surface. Especially, it is clear that some atomic S has been oxidized by air and detected the adsorbate of the SO 32- and SO 42- species. During exposure to the atmosphere, most of the adsorbed DMS and MT adsorbates desorb from the Pd TL surface. We thus conclude the Pd TL might be able to prevent the hydrogen storage materials from the sulfur poisoning. © 2012 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.apsusc.2012.05.098

    Web of Science

    Scopus

  21. Morphological and spectroscopic studies on enlargement of Pd nanoparticle in L-cysteine aqueous solution by AFM and XPS

    Tsukada C., Ogawa S., Niwa H., Nomoto T., Kutluk G., Namatame H., Taniguchi M., Yagi S.

    APPLIED SURFACE SCIENCE   267 巻   頁: 48 - 52   2013年2月

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    記述言語:日本語   出版者・発行元:Applied Surface Science  

    We have revealed the enlargement mechanism of Pd nanoparticles (NPs) on SiO 2 /Si by the AFM observation and the XPS measurement, when the Pd NPs react with the l-cysteine under water environment. Furthermore, the adsorbates on the Pd NPs/SiO 2 /Si have been confirmed by the XPS measurement. The Pd NPs with clean surface are fabricated and deposited on the SiO 2 /Si substrate by the gas evaporation method. In that aspect, the Pd NPs possess an interaction with the SiO 2 /Si surface. When the Pd NPs/SiO 2 /Si is reacted into the l-cysteine aqueous solution, the adsorbates originated from the l-cysteine exist on the Pd NPs surface. On the contrary, the l-cysteine hardly adsorb on the SiO 2 /Si. The enlargement of the Pd NPs is stimulated by the contributions of the H 2 O and/or the l-cysteine molecules because the Pd NPs can be more easily migrated on the SiO 2 /Si surface due to those contributions. © 2012 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.apsusc.2012.05.123

    Web of Science

    Scopus

  22. Adsorption reaction of L-cysteine on Au nanoparticle prepared by solution plasma

    Tsukada C., Mizutani T., Ogawa S., Nomoto T., Abe Y., Nameki H., Matsuo K., Kutluk G., Yagi S.

    e-Journal of Surface Science and Nanotechnology   11 巻   頁: 18 - 24   2013年2月

     詳細を見る

    出版者・発行元:e-Journal of Surface Science and Nanotechnology  

    We have investigated the L-cysteine adsorption reaction on the Au nanoparticles (NPs) prepared by means of the solution plasma method. The particle size of the Au NPs is estimated to be 2.4±1.0 nm as prepared. When the L-cysteine adds into the Au NPs colloidal solution, the solution color is quickly changed from red to dark blue. It is found that the adsorbates of L-cysteine thiolate, cystine and atomic sulfur exist on the Au NPs surface by sulfur K-edge NEXAFS. In addition, the Au NPs aggregate each other by the hydrogen bonding at carboxyl groups and produce the black colored precipitate. In this paper, we have revealed the adsorption behavior of the L-cysteine on the Au NPs by AFM, UV-vis, ζ-potential measurement and NEXAFS techniques. © 2013 The Surface Science Society of Japan.

    DOI: 10.1380/ejssnt.2013.18

    Scopus

  23. NEXAFS Study of Air Oxidation for Mg Nanoparticle Thin Film

    Ogawa S., Murakami S., Shirai K., Akanishi K., Ohta T., Yagi S.

    15TH INTERNATIONAL CONFERENCE ON THIN FILMS (ICTF-15)   417 巻 ( 1 )   2013年

     詳細を見る

    記述言語:日本語   出版者・発行元:Journal of Physics: Conference Series  

    The air oxidation reaction of Mg nanoparticle thin film has been investigated by Mg K-edge NEXAFS technique. It is revealed that MgO is formed on the Mg nanoparticle surfaces at the early stage of the air oxidation for Mg nanoparticle thin film. The simulation of NEXAFS spectrum using standard spectra indicates the existence of complex magnesium carbonates (x(MgCO 3).yMg(OH2).z(H2O)) in addition to MgO at the early stage of the air oxidation.

    DOI: 10.1088/1742-6596/417/1/012065

    Web of Science

    Scopus

  24. Aggregation mechanism of Pd nanoparticles in L-cysteine aqueous solution studied by NEXAFS and AFM

    Tsukada C., Ogawa S., Mizutani T., Kutluk G., Namatame H., Taniguchi M., Yagi S.

    APPLIED SURFACE SCIENCE   262 巻   頁: 184 - 187   2012年12月

     詳細を見る

    記述言語:日本語   出版者・発行元:Applied Surface Science  

    We focus on the biocompatibility of Pd nanoparticles (NPs) from the point of microscopic view. Thus, as the basic research for the biocompatibility, we have investigated the adsorbates on the Pd NPs surface and the aggregation mechanism for the Pd NPs on Si substrate after dipping into l-cysteine aqueous solution by means of NEXAFS measurement and AFM observation. The Pd NPs have been fabricated and deposited on the Si wafer by the gas evaporation method. Judging from the results of NEXAFS measurement, it is clear that the l-cysteine thiolate and atomic S exist on the Pd NPs surface. The results of AFM observation show that the Pd NPs aggregate. It is thought that the aggregation of the Pd NPs occurs by both the migration of the Pd NPs on Si wafer and the cross-linked reaction. © 2012 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.apsusc.2012.04.123

    Web of Science

    Scopus

  25. Adsorption behavior of L-cysteine on Ag nanoparticles under water environment studied by S K-edge NEXAFS

    Tsukada C., Yagi S., Nomoto T., Mizutani T., Ogawa S., Nameki H., Nakanishi Y., Kutluk G., Namatame H., Taniguchi M.

    APPLIED SURFACE SCIENCE   262 巻   頁: 231 - 233   2012年12月

     詳細を見る

    記述言語:日本語   出版者・発行元:Applied Surface Science  

    We have focused on the biocompatibility of the Ag nanoparticles. In this paper, we have fabricated the Ag nanoparticles by means of the solution plasma method. Since this method does not need to use the surfactant molecule, such as the water soluble polymer, the fabricated nanoparticle might possess the clean surface. The average diameter of the Ag nanoparticles is estimated to be 5.0 ± 1.1 nm. NEXAFS spectra show l-cysteine thiolate adsorbs on the Ag nanoparticle surface and l-cystine is synthesized. Though this reaction behavior is similar to the result of Rh(PVP, polyvinylpyrrolidone) system, in our previous study, the reaction speed for the Ag nanoparticle is much faster than that for the Rh(PVP) nanoparticle. © 2012 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.apsusc.2012.06.107

    Web of Science

    Scopus

  26. In-Situ XPS measurement of co nanoparticles fabricated by gas evaporation method

    Mizutani T., Ogawa S., Tsukada C., Nakanishi K., Ohta T., Yagi S.

    e-Journal of Surface Science and Nanotechnology   10 巻   頁: 351 - 354   2012年7月

     詳細を見る

    出版者・発行元:e-Journal of Surface Science and Nanotechnology  

    The cobalt and cobalt nitride nanoparticles (NPs) have been fabricated by gas evaporation method under helium or nitrogen gases environment. These chemical states and compositions have been investigated by in-situ XPS and those distributions have been estimated by AFM. It is found that both cobalt and cobalt nitride NPs are slightly oxidized by the residual gas in the chamber. The cobalt nitride NPs fabricated under nitrogen gas are including the nitrogen atoms at 4.7% and the nitrogen atoms have the chemical bonding with the cobalt atoms. © 2012 The Surface Science Society of Japan.

    DOI: 10.1380/ejssnt.2012.351

    Scopus

  27. IN-SITU MG K- AND PD L-3-EDGES NEXAFS INVESTIGATION OF MG-PD NANOPARTICLES

    Ogawa Satoshi, Mizutani Tsuyoshi, Ogawa Masahiro, Yogi Chihiro, Ohta Toshiaki, Yoshida Tomoko, Yagi Shinya

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

     詳細を見る

    記述言語:日本語  

    Web of Science

  28. 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

     詳細を見る

    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.

    Scopus

  29. 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

     詳細を見る

    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

  30. Size dependence of air oxidation for Mg nanoparticle 査読有り

    Ogawa S., Murakami S., Shirai K., Nakanishi K., Tsukada C., Ohta T., Yagi S.

    e-Journal of Surface Science and Nanotechnology   9 巻   頁: 315 - 321   2011年9月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:e-Journal of Surface Science and Nanotechnology  

    The size dependence of the air oxidation for Mg nanoparticles is studied by Mg K-edge NEXAFS and AFM techniques. In the case of the exposure to the air for 3 days, the degree of the air oxidation for Mg nanoparticles increases with reduction of the size of Mg nanoparticle. However, the opposite size dependence is observed in the case of the exposure to the air for 25 days, i.e. the air oxidation reaction for the smaller Mg nanoparticles is more inhibited in the case of long term exposure to the air. This size dependence is attributed to the occupation of the free spaces between Mg nanoparticles, which protects against the incursion of the air component molecules into the multilayer of Mg nanoparticles. © 2011 The Surface Science Society of Japan.

    DOI: 10.1380/ejssnt.2011.315

    Scopus

  31. Adsorption reaction of amino acid molecule on pd thin layer surface constructed by nano-dots under water environment

    Tsukada C., Ogawa S., Niwa H., Yagi S., Nomoto T., Kutluk G., Namatame H., Taniguchi M., Nomoto T., Namatame H., Taniguchi M.

    e-Journal of Surface Science and Nanotechnology   9 巻   頁: 289 - 292   2011年7月

     詳細を見る

    出版者・発行元:e-Journal of Surface Science and Nanotechnology  

    The adsorption reaction of L-cysteine on Pd thin layer surface constructed by nano-dots under water envi- ronment has been investigated by S K-edge NEXAFS with He-path system under atmospheric pressure. It is revealed that L-cysteine physisorbs on Pd/Al2O3/NiAl(111) substrate surface through the thiol group and the carboxyl one, and chemisorbed L-cysteine exists on the surface as L-cysteine thiolate. Before and after dipping the Pd/Al 2O3/NiAl(111) substrate into L-cysteine aqueous solution, the surface morphology is observed using AFM. The morphology of the Pd/Al 2O3/NiAl(111) substrate is composed of many nano-dots before dipping. After dipping, the nano-dots are enlarged. ©2011.289] 2011 The Surface Science Society of Japan.

    DOI: 10.1380/ejssnt.2011.289

    Scopus

  32. The spectroscopic study on the chemical state at Pd/Mg interface 査読有り

    Murakami S., Ogawa S., Shirai K., Tsukada C., Yagi S., Nakanishi K., Ohta T.

    e-Journal of Surface Science and Nanotechnology   9 巻   頁: 438 - 441   2011年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:e-Journal of Surface Science and Nanotechnology  

    The chemical state of interface between Pd and Mg layers has been investigated by XPS and NEXAFS methods. Since it is thought that the hydrogen storage ability strongly depends on the chemical state of the interface, we focus on the interface of the Pd-Mg. It is found that the different phase from bulk metal or oxide exists between Pd and Mg layers prepared by both DC magnetron sputtering and vacuum evaporation methods. From XPS and NEXAFS measurements, we have revealed that Pd loses the electron and Mg picks up one in this phase. It might be thought that the Pd-Mg alloy phase exists between Pd and Mg. © 2011 The Surface Science Society of Japan.

    DOI: 10.1380/ejssnt.2011.438

    Scopus

  33. Fabrication and characterization of magnesium nanoparticle by gas evaporation method 査読有り

    Ogawa S., Niwa H., Nomoto T., Yagi S.

    e-Journal of Surface Science and Nanotechnology   8 巻   頁: 246 - 249   2010年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:e-Journal of Surface Science and Nanotechnology  

    We have fabricated the Mg nanoparticles by the gas evaporation method. The AFM observation shows Mg nanoparticles fabricated under the several gas pressures of He have the average diameter of 3.6 nm to 8.0 nm. We have studied the in uence of the atmospheric oxidation for the chemical state of the Mg nanoparticles by the Mg K-edge NEXAFS technique. The NEXAFS measurement shows that the chemical state of MgCO3 exists on the most lateral surface of the Mg nanoparticles and the degree of atmospheric oxidation depends on the size of Mg nanoparticles.

    DOI: 10.1380/ejssnt.2010.246

    Scopus

  34. NEXAFS and XPS studies of (CH<inf>3</inf>)<inf>2</inf>S Adsorption on Rh(PVP) nanoparticle

    Niwa H., Ogawa S., Yagi S., Kutluk G., Namatame H., Taniguchi M.

    e-Journal of Surface Science and Nanotechnology   8 巻   頁: 233 - 236   2010年5月

     詳細を見る

    出版者・発行元:e-Journal of Surface Science and Nanotechnology  

    We have studied the adsorption reaction of dimethyl sulfide (DMS) on the Rh-polyvinylpyrrolidone (Rh(PVP)) nanoparticles by using AFM, XPS and NEXAFS techniques. The AFM images show the morphology of the Rh(PVP) nanoparticles depends on the amount of them. The XPS results indicate that the dissociation reaction of DMS into atomic S does not depend upon the existence of the Rh(PVP) nanoparticles. The NEXAFS results show that there is a strong chemical bonding between Rh(PVP) nanoparticle and atomic S. © 2010 The Surface Science Society of Japan.

    DOI: 10.1380/ejssnt.2010.233

    Scopus

  35. NEXAFS analysis of Mg nanoparticles oxidized in atmosphere 査読有り

    Ogawa S., Niwa H., Nakanishi K., Ohta T., Yagi S.

    IEEJ Transactions on Electronics, Information and Systems   130 巻 ( 10 ) 頁: 1746 - 1750   2010年

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEJ Transactions on Electronics, Information and Systems  

    The Mg nanoparticles have been fabricated by the gas evaporation method under the several He gas pressures. We have estimated the size of Mg nanoparticles by atomic force microscopy (AFM) observation and have studied the chemical state of Mg nanoparticles exposed to atmosphere by near-edge X-ray absorption fine structure (NEXAFS) technique. The average diameters of Mg nanoparticles fabricated under 3, 5 and 10 kPa of He are 3.6, 8.0 and 5.0 nm, respectively. It is found that the degree of atmospheric oxidation of Mg nanopaticles depends on the size of nanoparticles. © 2010 The Institute of Electrical Engineers of Japan.

    DOI: 10.1541/ieejeiss.130.1746

    Scopus

  36. XPS and NEXAFS analysis of dimethyl sulfide adsorbed on the Rh(PVP) nanoparticle surface

    Niwa H., Ogawa S., Kutluk G., Yagi S.

    IEEJ Transactions on Electronics, Information and Systems   130 巻 ( 10 )   2010年

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    出版者・発行元:IEEJ Transactions on Electronics, Information and Systems  

    We have studied the adsorption reaction of dimethyl sulfide (DMS: (CH 3)2S) on the surface of Rh(PVP) nanoparticles by using AFM, XPS and NEXAFS techniques. The AFM images show the degree of dispersion of the Rh(PVP) nanoparticles depends on the amount of them. The in-situ XPS results indicate that the dissociation reaction of DMS into atomic S does not depend upon the existence of the Rh(PVP) nanoparticles. The NEXAFS results show that there is a strong chemical bonding between Rh(PVP) nanoparticle and atomic S. The ex-situ XPS results show the atomic S adsorbed on the Rh(PVP) nanoparticles partially desorb by exposing to the air. © 2010 The Institute of Electrical Engineers of Japan.

    DOI: 10.1541/ieejeiss.130.1751

    Scopus

  37. 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 2010 - 2nd International Conference, Conference Proceedings     頁: 274 - 279   2010年

     詳細を見る

    出版者・発行元:NANOCON 2010 - 2nd International Conference, Conference Proceedings  

    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

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

    Yoshida Tomoko, Yamamoto Naoto, Mizutani Tsuyoshi, Yamamoto Muneaki, Ogawa Satoshi, Yagi Shinya, Nameki Hirofumi, Yoshida Hisao

    CATALYSIS TODAY   303 巻   頁: 320 - 326   2018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: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

    Web of Science

    Scopus

  39. Fabrication and in/ex situ XPS Characterization of Rh Nanoparticles

    Koda Yuki, Sumida Hirosuke, Ogawa Satoshi, Tsukada Chie, Namatame Hirofumi

    E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY   15 巻   頁: 50 - 54   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:e-Journal of Surface Science and Nanotechnology  

    Rh nanoparticles have been fabricated by the evaporation method using the He gas in the Rh evaporation chamber, connected with the pre-evacuation chamber of BL6N1 at Aichi Synchrotron Radiation Center (Aichi SR). The electronic and geometric properties of the Rh nanoparticles have been verified without atmosphere exposure (in situ XPS) and after atmosphere exposure (ex situ XPS) using SR-XPS and TEM. The size of Rh nanoparticles is estimated 1.8±0.5 nm in diameter and deposited on a substrate. Judging from the result of the in situ XPS analysis with photon energy of 2.0 keV and 3.5 keV, the surface of the deposited Rh nanoparticles without atmosphere exposure is the metallic state. On the other side, the outermost surface changes into Rh oxide after atmosphere exposure even in a short time. For a long time atmosphere exposure moreover, the Rh oxide increases in the depth direction, and the deep area is in the higher oxidation state.

    DOI: 10.1380/ejssnt.2017.50

    Web of Science

    Scopus

  40. Influence of CO 2 and H 2 O on Air Oxidation of Mg Nanoparticles Studied by NEXAFS 査読有り

    Journal of Surface Analysis   17 巻 ( 3 ) 頁: 319 - 323   2011年1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(国際会議プロシーディングス)  

    DOI: 10.1384/jsa.17.319

▼全件表示

講演・口頭発表等 2

  1. 液中プラズマ法で作製したナノ粒子 招待有り

    小川智史

    2021年度第3回人工光合成研究拠点 講演会   2021年6月17日  大阪市立大学人工光合成研究センター

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    開催年月日: 2021年6月

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    開催地:オンライン開催  

  2. Mg-Mnナノ粒子の軟X線XAFS分析

    小川智史

    日本金属学会 2022年春期(第170回)  2021年3月16日  公益社団法人 日本金属学会

     詳細を見る

    開催年月日: 2021年3月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:オンライン開催  

共同研究・競争的資金等の研究課題 1

  1. ソリューションプラズマ法を応用した新奇Mg-Ni系水素吸蔵合金ナノ粒子の創製とその評価

    2015年4月 - 2016年12月

    日東学術振興財団助成金 

      詳細を見る

    資金種別:競争的資金

科研費 7

  1. コアシェル構造を有する新奇Mg-Pdナノ粒子の開発と水素吸放出特性評価

    2014年10月 - 2016年3月

    科学研究費補助金 

      詳細を見る

    担当区分:研究代表者 

  2. 金属ナノ粒子を用いた高い水素吸放出特性を有する新奇材料の開発

    2011年4月 - 2014年3月

    科学研究費補助金  特別研究員奨励費(DC1)

      詳細を見る

    担当区分:研究代表者 

  3. 非混合性金属のナノ界面構造が誘起する内部応力場下の水素貯蔵・供給反応機構と制御

    研究課題/研究課題番号:21H01744  2021年4月 - 2024年3月

    科学研究費助成事業  基盤研究(B)

    浅野 耕太, Kim Hyunjeong, 和田 武, 榊 浩司, 片岡 理樹, CHARBONNIER Veronique, 小川 智史

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    担当区分:研究分担者 

    本研究では、再生可能エネルギー導入拡大に向けて、電力の安全・安定供給に利用する高水素密度かつ低材料コストの水素貯蔵材料を開発する。軽量で安価なマグネシウムなどをベースとして、これまでの課題であった高い反応温度を低下させることを目的とする。産総研、名古屋大学および東北大学がそれぞれ独自にもつ材料創製法を駆使することで、目的とする材料と水素の反応温度低下を実現する。

  4. ナノ界面を制御したMg複合ナノ粒子の創製による常温付近での高密度水素貯蔵

    研究課題/研究課題番号:18K14089  2018年4月 - 2022年3月

    科学研究費助成事業  若手研究

    小川 智史

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    担当区分:研究代表者  資金種別:競争的資金

    配分額:4160000円 ( 直接経費:3200000円 、 間接経費:960000円 )

    年々厳格化しつつある温室効果ガスの排出規制をクリアしつつ持続可能な成長を達成するためには、エネルギー利用におけるよりいっそうの効率化が望まれる。エネルギーの利便性向上のために長期安定貯蔵が可能な水素エネルギーの普及が肝要であり、水素利用の普及を目指して本研究ではMgをベースとした安価な水素吸蔵材料の開発を行っている。課題として水素吸蔵時に300℃程度の高温条件を必要とするため、実用に向けては水素吸放出時のエネルギー効率の向上が必要である。本研究ではMgのナノ粒子化による比表面積の増加と、Mgと遷移金属(TM)を複合化することで生じるMg-TM界面付近の「歪み」を利用することで、Mgの水素吸放出温度を常温付近まで低下させることを目的としている。
    令和2年度においては前年度までに開発と評価を終えた高真空トランスファーベッセルと水素化反応トランスファーベッセルを用いてMg-Mnナノ粒子のMg K吸収端近傍におけるX線吸収微細構造(Mg K-edge NEXAFS)測定を実施した。Mnに対してMgの割合の多いMgリッチなMg-Mnナノ粒子では、そのNEXAFSスペクトルは標準試料のスペクトルと酷似していた。一方で、徐々にMn組成を増やしたMnリッチな試料では、NEXAFSスペクトル形状が変化していくことが明らかとなった。NEXAFSスペクトルの形状変化はMg原子周りの配位環境の変化を示しており、MgとMnの複合化とナノ粒子化によって「歪み」が導入されたことを示唆している。
    令和2年度は全世界的に新型コロナウイルス感染症(COVID-19)が猛威を振るい、人的移動が制限されたことによって本研究に多大な支障をきたした。そのため、研究期間を延長することで、Mg-Mnナノ粒子の物性評価を推進していくこととする。
    今後はMg-Mnナノ粒子における「歪み」が水素吸蔵前後で可逆的に変化し得るか調べるとともに、Mg-Mnナノ粒子の水素吸蔵量を評価する。さらにMgと非混合性の他の遷移金属(Ti, Cr)とMgを複合化させたナノ粒子を作製することで、「歪み」と水素吸蔵量との関係を系統的に調べていく。

  5. コアシェル構造を有する新奇Mg-Pdナノ粒子の開発と水素吸放出特性評価

    研究課題/研究課題番号:26889034  2014年8月 - 2016年3月

    科学研究費助成事業  研究活動スタート支援

    小川 智史

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    担当区分:研究代表者 

    配分額:2730000円 ( 直接経費:2100000円 、 間接経費:630000円 )

    本研究はMgの核とPdの外殻からなるコアシェル構造を有するナノ粒子(Pd/Mgナノ粒子)の作製を目的として行なわれた。Pd/Mgナノ粒子の作製にはガス中蒸発法を用い、ナノ粒子作製装置を2段に連結させることでMgコアとPdシェルの形成を試みたが、PdがMgナノ粒子表面上でナノ粒子状になってしまい、MgコアをPdシェルで完全に被覆することは達成できなかった。しかし、このナノ粒子材料の水素吸蔵量を調べたところ、9割近くのMg原子が水素化されており、既往の結果をしのぐ性能が得られた。X線を用いた化学状態分析の結果、Pdナノ粒子とMgナノ粒子の間では金属間化合物が形成されていることが明らかとなった。

  6. コアシェル構造を有する新奇Mg-Pdナノ粒子の開発と水素吸放出特性評価

    2014年10月 - 2016年3月

    日本学術振興会  科学研究費助成事業  若手研究(スタートアップ)

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    資金種別:競争的資金

  7. 金属ナノ粒子を用いた高い水素吸放出特性を有する新奇材料の開発

    2011年4月 - 2014年3月

    日本学術振興会  科学研究費助成事業  特別研究員奨励費

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    資金種別:競争的資金

▼全件表示

 

担当経験のある科目 (本学) 13

  1. エネルギー理工学実験第2A

    2022

  2. エネルギー理工学実験第1

    2022

  3. 量子ビーム分析科学

    2022

  4. 環境機能材料工学

    2022

  5. エネルギー理工学実験第1

    2021

  6. エネルギー理工学実験第2A・B

    2021

  7. エネルギー理工学実験第2A・B

    2020

  8. エネルギー理工学実験第1

    2020

  9. エネルギー理工学実験第1

    2019

  10. エネルギー理工学実験第2A・B

    2019

  11. 量子エネルギー工学学生実験第2A・B

    2018

  12. 量子エネルギー工学学生実験第1

    2017

  13. 量子エネルギー工学実験第2A・B

    2017

▼全件表示

 

社会貢献活動 2

  1. 2022年度 EXAFS解析講習会

    役割:講師

    名古屋大学シンクロトロン光研究センター  2022年11月

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    対象: 大学院生, 研究者, 企業

    種別:セミナー・ワークショップ

  2. 2022年度 XAFS入門講習会

    役割:講師

    名古屋大学シンクロトロン光研究センター  2022年7月

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    対象: 大学院生, 研究者, 企業

    種別:セミナー・ワークショップ