Country：Japan

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.apsusc.2021.151979

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Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

A CdS photoanode with a smooth surface can stably oxidize [Fe(CN)₆]⁴⁻ by densely forming K₂Cd[Fe(CN)₆] on the CdS surface during photocorrosion.

DOI： 10.1039/d1nj06073b

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

Meso-porous α-Ga₂O₃ showing quite high photocatalytic activity for CO₂ reduction with water is successfully synthesized from liquid Ga metal.

DOI： 10.1039/d1ra09039a

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PubMed

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

The H₂ production rates increased with SSA, irrespective of the phases, while the CO production rates increased with the abundance of α-Ga₂O₃.

DOI： 10.1039/d1nj05245d

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Vacuum and Surface Science  

<p> 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. </p>

DOI： 10.1380/ejssnt.2022-003

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CiNii Research

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acsomega.1c04730

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PubMed

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.cattod.2020.04.063

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：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

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acsomega.1c02088

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry  

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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Language：Japanese   Publisher：The Discussion Group of X-Ray Analysis, The Japan Society for Analytical Chemistry  

DOI： 10.57415/xshinpo.52.0_261

CiNii Research

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.apsusc.2020.148680

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Publishing type：Research paper (scientific journal)   Publisher：SPIE-Intl Soc Optical Eng  

DOI： 10.1117/1.JNP.14.046011

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Public Library of Science (PLoS)  

DOI： 10.1371/journal.pone.0239774

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PubMed

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.cattod.2019.12.035

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.jpcc.0c03822

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Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

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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Other Link： https://iopscience.iop.org/article/10.1088/2053-1591/aba394/pdf

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Chemical Society of Japan  

<p>We have examined photocatalytic activities of Ga₂O₃ supported by various metal oxides for water splitting and CO₂ reduction with water under UV light irradiation. The Ga₂O₃ photocatalyst supported by metal oxides was prepared by an impregnation method. We have found that some oxides used as a supporting oxide of Ga₂O₃ photocatalyst improve activities of water splitting and CO₂ reduction. In particular, the CO production rates are well correlated to various properties of the supporting oxide. These oxides satisfy the following three criteria significantly enhancing the CO production rate. (1) Their band gap is wider than that of Ga₂O₃ and the position of its conduction band is at a negative potential with respect to that of Ga₂O₃. (2) They are not miscible with Ga₂O₃ and (3) mixed phases of α and γ or defective γ phase of Ga₂O₃ are well dispersed on them exhibiting columnar shape. These criteria would be useful for further improvement of the activity for photocatalytic CO₂ reduction with water by Ga₂O₃.</p>

DOI： 10.1246/bcsj.20190366

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CiNii Research

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

<p>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.</p>

DOI： 10.1039/c9cp06988g

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Vacuum and Surface Science  

<p>It is well known that Ag loaded Gallium oxide (Ag/Ga₂O₃) promotes photocatalytic CO₂ reduction to CO. However, the role of the Ag co-catalyst in the CO₂ reduction has not been clarified. We have intended to find the relationship between the state of Ag loaded on Ga₂O₃ and their activity for the photocatalytic CO₂ reduction. To achieve this, we have tried to control and stabilize the loading state of Ag on Ga₂O₃ during their use for the photocatalytic CO₂ reduction by adding methanol as a reducing agent. It is confirmed that methanol stabilizes the particle sizes of Ag nanoparticles (Ag-NPs) loaded on Ga₂O₃ under the photocatalytic CO₂ reduction condition and is hardly decomposed to produce CO. Using Ga₂O₃ loaded with size-controlled Ag-NPs as a photocatalyst for the CO₂ reduction, it is found that Ag-NPs with their sizes within 10—30 nm are active sites for the photocatalytic CO₂ reduction 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 CO₂ reduction.</p>

DOI： 10.1380/ejssnt.2020.168

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CiNii Research

Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

<p>We have succeeded in synthesizing black phosphorus employing a one-pot solvothermal reaction of red phosphorous and ethylenediamine used as a solvent.</p>

DOI： 10.1039/c9ta13441g

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Vacuum and Surface Science  

<p>We have prepared La₂O₃ supported Ga₂O₃ (Ga₂O₃/La₂O₃) photocatalyst to improve the photocatalytic activity of Ga₂O₃ for CO₂ reduction with water under ultraviolet light irradiation without a noble metal cocatalyst. Significant improvement on both CO₂ reduction and water splitting was attained compared with those for non-supported Ga₂O₃ and La₂O₃. The improvement is attributed to the transformation of the La₂O₃ surface to NaLa(CO₃)₂ during the photocatalytic reduction tests in aqueous solution of NaHCO₃. NaLa(CO₃)₂ was preferentially formed on the surface of La₂O₃ without changing Ga₂O₃ resulting in the structure of Ga₂O₃ supported by NaLa(CO₃)₂. Once NaLa(CO₃)₂ fully covered the surface of La₂O₃, the high catalytic activity was kept long.</p>

DOI： 10.1380/ejssnt.2020.110

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CiNii Research

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.apcatb.2019.118247

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Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.7567/1347-4065/ab4601

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Other Link： http://iopscience.iop.org/article/10.7567/1347-4065/ab4601/pdf

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acsomega.9b02979

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acsomega.9b02977

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

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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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/anie.201906349

Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.1088/1361-6528/ab2092

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Other Link： http://iopscience.iop.org/article/10.1088/1361-6528/ab2092/pdf

Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

<p>Air-stable and highly reusable cobalt ion-doped titanium oxide catalyst was developed for alkene hydrosilylation.</p>

DOI： 10.1039/c9gc01981b

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Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.apcatb.2019.03.009

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.jpcc.9b03640

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Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1246/cl.190311

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Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.7567/1347-4065/ab2830

Other Link： http://iopscience.iop.org/article/10.7567/1347-4065/ab2830/pdf

Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.7567/1347-4065/ab09c8

Other Link： https://iopscience.iop.org/article/10.7567/1347-4065/ab09c8

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.cplett.2019.02.049

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acsomega.9b00048

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PubMed

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

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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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

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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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

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 NaTaO_3‐xN_y. 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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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

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‐Ga₂O_3. 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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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

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 (&gt;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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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Vacuum and Surface Science  

<p>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 irradiation. [DOI: 10.1380/ejssnt.2018.262]</p>

DOI： 10.1380/ejssnt.2018.262

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CiNii Research

Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.1088/1361-6463/aabe44

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Other Link： http://iopscience.iop.org/article/10.1088/1361-6463/aabe44/pdf

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry  

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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Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.jphotochem.2017.11.010

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.cattod.2017.09.029

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.cattod.2017.08.047

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Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.cattod.2017.09.025

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Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

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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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.surfcoat.2018.02.026

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

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 (&gt;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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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/anie.201701627

Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

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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Other Link： http://stacks.iop.org/1347-4065/55/i=10/a=106202?key=crossref.69ed7b7971d62ec6f8c9129ecd2a2c59

Language：English   Publisher：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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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1088/1742-6596/712/1/012074

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.1088/1742-6596/712/1/012056

Other Link： http://stacks.iop.org/1742-6596/712/i=1/a=012056?key=crossref.49278627889fb72fe760993783b12a62

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Vacuum and Surface Science  

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]

DOI： 10.1380/ejssnt.2016.150

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CiNii Research

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.nimb.2015.07.035

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Scopus

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.nimb.2015.04.010

Web of Science

Scopus

Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.7567/JJAP.54.126201

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Scopus

Other Link： http://stacks.iop.org/1347-4065/54/i=12/a=126201?key=crossref.8de312670aa262f2ebe1e2556b349c69

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.apsusc.2015.04.139

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Scopus

Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

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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Scopus

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.ijhydene.2015.05.031

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Scopus

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.ijhydene.2015.04.087

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Scopus

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.nimb.2015.07.031

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Scopus

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.jcis.2014.12.097

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Scopus

PubMed

Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.1088/1757-899x/76/1/012001

Other Link： http://stacks.iop.org/1757-899X/76/i=1/a=012001?key=crossref.7841256626afcf78ba29911c124eb567

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Vacuum and Surface Science  

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 signicantly in the Pd NPs. [DOI: 10.1380/ejssnt.2015.343]

DOI： 10.1380/ejssnt.2015.343

Scopus

CiNii Research

CiNii Research

CiNii Research

Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

<p>The structure and function of the Ag cocatalyst in Ag loaded Ga₂O₃ photocatalysts for photocatalytic CO₂ reduction with water were investigated. It was found that around 1 nm sized Ag clusters had strong interactions with the Ga₂O₃ surface and promoted the formation of bidentate formate species as the reaction intermediate for the CO production.</p>

DOI： 10.1039/c5ta04815j

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Scopus

Publishing type：Research paper (scientific journal)   Publisher：Wiley  

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 visible‐light 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 from the present results to estimate the critical depth of nitrogen distribution effectively reactive to be 13 ± 5 nm from the surface. Copyright © 2014 John Wiley &amp; Sons, Ltd.

DOI： 10.1002/sia.5542

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Scopus

Publishing type：Research paper (scientific journal)   Publisher：Wiley  

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 630 nm 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. Copyright © 2014 John Wiley &amp; Sons, Ltd.

DOI： 10.1002/sia.5567

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Scopus

Publishing type：Research paper (scientific journal)   Publisher：Wiley  

We have fabricated the Ni nanoparticles with a clean surface by the gas evaporation method and clarified the hydrogen storage property by using atomic force microscope (AFM), X‐ray photoelectron spectroscopy (XPS) and quartz crystal microbalance (QCM) measurements. The diameter has been estimated as 4.0 ± 1.5 nm by AFM observation. The Ni nanoparticles possess a clean surface, because the surface chemical state has been confirmed as mainly metallic state by XPS. The hydrogen storage property has been investigated by QCM from the vacuum to the atmospheric pressure of the hydrogen at 300 K. The plateau pressure of the Ni nanoparticles and a maximum 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 nanoparticles makes it possible to observe the adsorption/desorption reaction and (iii) the Ni hydride is stable under the vacuum condition. The chemical shift of Ni 2p_3/2 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. Copyright © 2014 John Wiley &amp; Sons, Ltd.

DOI： 10.1002/sia.5566

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Scopus

Publishing type：Research paper (scientific journal)   Publisher：Wiley  

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. Copyright © 2014 John Wiley &amp; Sons, Ltd.

DOI： 10.1002/sia.5647

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Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.7567/JJAP.53.11RA03

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Scopus

Other Link： http://stacks.iop.org/1347-4065/53/i=11S/a=11RA03?key=crossref.abf0db48a09f1feadf9e0e6809c9acc1

Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.apsusc.2014.03.022

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Scopus

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.69.1.2.0_270_1

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Vacuum and Surface Science  

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 WO₃ 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. [DOI: 10.1380/ejssnt.2014.343]

DOI： 10.1380/ejssnt.2014.343

Scopus

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：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

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Vacuum and Surface Science  

Ag loaded Ga₂O₃ (Ag/Ga₂O₃) has exhibited photocatalytic activity for CO₂ reduction with water to produce CO as well as for water splitting to H₂ and O₂. In-situ FT-IR measurements have shown CO₃ stretching vibration bands assignable to carbonate and bicarbonate species when CO₂ molecules chemisorbed on the catalyst surface. These species change to bidentate formate species under photoirradiation. It subsequently converts to CO by interacting with water molecules, not chemisorbed OH on the catalyst surface. This result suggests that formate species is an intermediate of the photocatalytic CO₂ reduction. On the other hand, Au loaded Ga₂O₃ (Au/Ga₂O₃) has produced H₂ predominantly with a very small amount of CO formation, since the less amount of CO₂ molecules chemisorb on Au/Ga₂O₃. FT-IR measurements of the Ag/Ga₂O₃ with high Ag loading have shown carbonate species due to the adsorption of atmospheric CO₂ on hydroxyl group. The carbonate species is too unstable under photoirradiation to convert into formate species, but is stabilized as CO₃^2- species by the reaction with water. XANES analysis has revealed that atomically dispersed Ag metal species may be effective for the adsorption of CO₂ and the subsequent conversion into formate species to promote the photocatalytic CO₂ reduction. [DOI: 10.1380/ejssnt.2014.299]

DOI： 10.1380/ejssnt.2014.299

Scopus

CiNii Research

Publisher：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

Publisher：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

Publisher：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.

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Vacuum and Surface Science  

We have prepared silver-loaded gallium oxide (Ag/Ga₂O₃) 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/Ga₂O₃ (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. [DOI: 10.1380/ejssnt.2014.263]

DOI： 10.1380/ejssnt.2014.263

Scopus

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST 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 &gt; 700 nm) in decolorization of methylene blue without any co-catalyst. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4798597]

DOI： 10.1063/1.4798597

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Scopus

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Photocatalytic steam reforming of methane (PSRM; 2 H2O (g) + CH4 -&gt; 4 H-2 + CO2) was examined over metal-loaded K2Ti6O13 photocatalysts. Although the production rate was improved by loading Pt cocatalyst on the K2Ti6O13 photocatalyst, unfavorable formation of CO and gradual deactivation of photocatalyst were observed. On the other hand, a Rh-loaded K2Ti6O13 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 Na2Ti6O13 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.

DOI： 10.1021/cs2006229

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

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 nanopartide 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. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apcatb.2011.12.029

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Scopus

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author  

Web of Science

Web of Science

Publisher：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

Publisher：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

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

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.

Authorship：Lead author  

Language：English   Publishing type：Research paper (scientific journal)  

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

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

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.

Language：Japanese  

Language：English   Publishing type：Research paper (scientific journal)  

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.

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

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.

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：Japanese  

Language：Japanese  

Authorship：Lead author   Language：Japanese  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

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.

Authorship：Lead author   Language：Japanese  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

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.

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

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.

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

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.

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：Japanese  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.56.2.4.0_801_3

CiNii Research

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：Japanese  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Total pages：x, 341p   Language：Japanese

CiNii Books

Language：Japanese

Language：Japanese

Language：Japanese

Language：Japanese

Event date： 2009.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2009.1

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Country：Japan  

Event date： 2008.6

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Country：Japan  

Event date： 2007.12

Language：English   Presentation type：Poster presentation  

Event date： 2007.11

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Country：Japan  

Event date： 2007.9

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Country：Japan  

Event date： 2007.9

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Country：Japan  

Event date： 2007.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2007.3

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Country：Japan  

Event date： 2007.2

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Country：Japan  

Event date： 2007

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Country：Japan  

Event date： 2006.12

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Event date： 2006.11

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Country：Japan  

Event date： 2006.9

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Country：Japan  

Event date： 2006.9

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Country：Japan  

Event date： 2006.7

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Event date： 2006.7

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Event date： 2006.1

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Country：Japan  

Event date： 2005.11

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Country：Japan  

Event date： 2005.10

Language：English   Presentation type：Poster presentation  

Event date： 2005.8

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Event date： 2005.1

Language：Japanese   Presentation type：Oral presentation (invited, special)  

Country：Japan  

Application no：10/727,557  Date applied：2003.12

Announcement no：US2004/0163942 A1 

Date registered：2004.8 

Country of applicant：Foreign country  

Date applied：2003.12

Announcement no：US 2004-0163942 A1  Date announced：2004.8

Country of applicant：Foreign country   Country of acquisition：Foreign country

Application no：特願2003-312863  Date applied：2003.9

Announcement no：特開2005-83756 

Patent/Registration no：特許第3861154号  Date registered：2006.10 

Country of applicant：Domestic  

Date applied：2003.9

Announcement no：2005-083756  Date announced：2005.3

Patent/Registration no：03861154 

Country of applicant：Domestic   Country of acquisition：Domestic

Application no：特願2002-362541  Date applied：2002.12

Announcement no：特開2004-191315 

Patent/Registration no：特許第3837528号  Date registered：2006.8 

Country of applicant：Domestic  

Date applied：2002.12

Announcement no：2004-191315  Date announced：2004.7

Patent/Registration no：03837528 

Country of applicant：Domestic   Country of acquisition：Domestic

Application no：特願2001-152599  Date applied：2001.5

Announcement no：特開2002-338201 

Country of applicant：Domestic  

Date applied：2001.5

Announcement no：2002-338201  Date announced：2002.11

Country of applicant：Domestic   Country of acquisition：Domestic

Applicant：吉田朋子, 田辺哲朗, 吉田寿雄,服部 忠

Application no：2000-155089  Date applied：2000.5

Announcement no：2001-334262 

Patent/Registration no：第3564532号  Date registered：2004.6 

Country of applicant：Domestic  

Date applied：2000.5

Announcement no：2001-334262  Date announced：2001.12

Patent/Registration no：03564532 

Country of applicant：Domestic   Country of acquisition：Domestic

Type：Academic society, research group, etc. 

Type：Academic society, research group, etc. 

Type：Academic society, research group, etc. 

Type：Academic society, research group, etc. 

Type：Academic research 

Type：Academic society, research group, etc.