研究者詳細 - 坪田　敏樹

論文 - 坪田　敏樹

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(Au@Ag)@Au double shell nanoparticles loaded on rutile TiO<inf>2</inf>for photocatalytic decomposition of 2-propanol under visible light irradiation 査読有り国際誌

Kamimura S., Miyazaki T., Zhang M., Li Y., Tsubota T., Ohno T.

Applied Catalysis B: Environmental 180 255 - 262 2016年07月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2015 Elsevier B.V. We synthesized (core@shell)@shell ((Au@Ag)@Au) nanoparticles (NPs) by a multistep citrate reduction method for utilization as photosensitizers of TiO 2 . The (Au@Ag)@Au NPs exhibited strong photoabsorption in visible light response due to LSPR excitation of the Ag shell, and its LSPR characteristics were stable under visible light irradiation for a long time because oxidation of the Ag shell was prevented by the outermost Au shell. Furthermore, we successfully loaded (Au@Ag)@Au NPs on rutile TiO 2 by an impregnation method. (Au@Ag)@Au/TiO 2 could oxidize 2-propanol into acetone and CO 2 under visible light irradiation (λ > 440nm), and its acetone evolution rate was approximately 15-times higher than that of Au/TiO 2 . From a comparison of action spectra for acetone evolution and the Kubelka-Munk function, it was confirmed that photocatalytic activity of (Au@Ag)@Au/TiO 2 was induced by photoabsorption based on LSPR excitation of the Ag shell. In addition, photoelectrochemical measurements revealed electron injection from LSPR-excited (Au@Ag)@Au NPs into TiO 2 under visible light irradiation. We proposed the photocatalytic reaction process of (Au@Ag)@Au/TiO 2 in conjunction with optical, structural and photoelectrochemical properties.

DOI： 10.1016/j.apcatb.2015.06.037

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Improvement of selectivity for CO<inf>2</inf>reduction by using Cu<inf>2</inf>ZnSnS<inf>4</inf>electrodes modified with different buffer layers (CdS and In<inf>2</inf>S<inf>3</inf>) under visible light irradiation 査読有り国際誌

Kamimura S., Sasaki Y., Kanaya M., Tsubota T., Ohno T.

RSC Advances 6 ( 113 ) 112594 - 112601 2016年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

© The Royal Society of Chemistry. Cu 2 ZnSnS 4 (CZTS) electrodes modified with different n-type buffer layers (CdS and In 2 S 3 ) were used as photocathodes for CO 2 reduction under visible light irradiation (420 < λ < 800 nm) in aqueous media. Compared to a bare CZTS electrode, CZTS electrodes modified with n-type buffer layers (CdS and In 2 S 3 ), by which a p-n heterojunction between CZTS and the n-type buffer layer is formed, showed a significant increase in the photocurrent assigned to CO 2 reduction. In addition, product selectivity of CO 2 reduction was improved by surface modification with an n-type buffer layer: that is, selective CO 2 reduction into CO was achieved by using a CdS/CZTS electrode, while HCOOH selectivity was observed over an In 2 S 3 /CZTS electrode. In this study, we investigated the photoelectrochemical properties of CZTS electrodes modified with n-type buffer layers (CdS and In 2 S 3 ) in conjunction with the structural and optical properties, and we investigated their activity for PEC CO 2 reduction.

DOI： 10.1039/c6ra22546b

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Photocatalytic reduction of CO<inf>2</inf>over exposed-crystal-face-controlled TiO<inf>2</inf>nanorod having a brookite phase with co-catalyst loading 査読有り

Ohno T., Higo T., Murakami N., Saito H., Zhang Q., Yang Y., Tsubota T.

Applied Catalysis B: Environmental 152-153 ( 1 ) 309 - 316 2014年06月

記述言語：英語掲載種別：研究論文（学術雑誌）

Photocatalytic reduction of carbon dioxide (CO 2 ) was carried out using exposed-crystal- face-controlled titanium(IV) oxide (TiO 2 ) having a brookite phase. Methanol (CH 3 OH) was detected as the main product, and trace amounts of formic acid, carbon monoxide, methane, and hydrogen were also detected in some cases. The prepared nanorod-shaped brookite TiO 2 with large {210} and small {212} exposed crystal faces showed larger CH 3 OH generation than that of commercial brookite TiO 2 powder (Kojundo Chemical Laboratory Co., Ltd.). The activity of a brookite TiO 2 nanorod for CO 2 reduction depended on its aspect ratio because the {210} crystal faced worked as a reduction site, whereas an oxidation site was assigned to {212} crystal faces. Photodeposition of gold (Au) or silver (Ag) nanoparticles on the nanorod-shaped brookite TiO 2 induced a dramatic increase in CH 3 OH production because the deposited metal particles work as reductive sites for multi-electron reduction of CO 2 . Among the co-catalyst-loaded brookite TiO 2 nanorods, nanorod-shaped brookite TiO 2 loaded with Ag showed higher activity. The source of carbon of CH 3 OH obtained by CO 2 reduction is discussed on the basis of results of a labeling experiment using 13 CO 2 . © 2014 Elsevier B.V.

DOI： 10.1016/j.apcatb.2014.01.048

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Complete oxidation of acetaldehyde over a composite photocatalyst of graphitic carbon nitride and tungsten(VI) oxide under visible-light irradiation 査読有り

Jin Z., Murakami N., Tsubota T., Ohno T.

Applied Catalysis B: Environmental 150-151 479 - 485 2014年05月

記述言語：英語掲載種別：研究論文（学術雑誌）

Graphitic carbon nitride (g-C 3 N 4 ) was prepared by heating melamine and then its specific surface area was enlarged by hydrothermal treatment in aqueous sodium hydroxide solution. The g-C 3 N 4 samples were blended with tungsten(VI) oxide (WO 3 ) using a planetary mill in order to improve photocatalytic activity. The composite photocatalyst with optimized amounts of these contents showed higher photocatalytic activity for decomposition of acetaldehyde under visible-light irradiation than did original samples. From the results, we concluded that the composite photocatalyst utilizes both high oxidation ability of WO 3 and high reduction ability of g-C 3 N 4 by Z-scheme charge transfer. © 2014 Elsevier B.V.

DOI： 10.1016/j.apcatb.2013.12.048

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Synthesis of nanofibrous carbon with herringbone structure on Ni-supported SiC particles using hot CVD apparatus 査読有り

Tsubota T., Matsuo H., Murakami N., Ohno T., Yajima H.

Diamond and Related Materials 48 104 - 109 2014年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

A nanofibrous carbon material having a herringbone structure was synthesized using Ni-supported silicon carbide (SiC) particles as the catalyst for the hot chemical vapor deposition (CVD) process using CH 4 as carbon source. The amount of the deposits during the CVD process strongly depended on the CVD treatment temperature. The enhancement of weight and the TG data indicated that the quantity synthesis of the deposits was achieved at 823 K. The specific surface area of the deposits was estimated at ca. 120 m 2 g - 1 . It was confirmed from the TEM images that the deposits synthesized in this study had a herringbone-like structure. From the data of Raman spectra and XRD patterns, the herringbone-like structure started to deposit after 30 minutes in the case of 823 K. The Ni-supported SiC can be used as the catalyst for the synthesis of nanofibrous carbon materials. © 2014 Elsevier B.V.

DOI： 10.1016/j.diamond.2014.07.009

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Photocatalytic reduction of carbon dioxide over shape-controlled titanium(IV) oxide nanoparticles with co-catalyst loading 査読有り

Murakami N., Saruwatari D., Tsubota T., Ohno T.

Current Organic Chemistry 17 ( 21 ) 2420 - 2426 2013年12月

記述言語：英語掲載種別：研究論文（学術雑誌）

Photocatalytic reduction of carbon dioxide (CO 2 ) was carried out using titanium(IV) oxide (TiO 2 ). Methanol (CH 3 OH) was detected as the main product, and trace amounts of formic acid, carbon monoxide, methane, and hydrogen were also detected. The prepared decahedral-shaped anatase TiO 2 with larger {011} and smaller {001} exposed crystal faces showed larger CH 3 OH generation than that of commercial anatase TiO 2 powder, ST-01 (Ishihara Sangyo Co.). Photodeposition of silver and gold nanoparticles on the decahedralshaped anatase TiO 2 induced an increase in CH 3 OH production because the deposited metal particles work as reductive sites for multielectron reduction of CO 2 . © 2013 Bentham Science Publishers.

DOI： 10.2174/13852728113179990055

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Development of highly efficient sulfur-doped TiO<inf>2</inf>photocatalysts hybridized with graphitic carbon nitride 査読有り

Kondo K., Murakami N., Ye C., Tsubota T., Ohno T.

Applied Catalysis B: Environmental 142-143 362 - 367 2013年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

Graphitic carbon nitride (g-C 3 N 4 ) has attracted much attention as a metal-free semiconductor having visible-light absorption and relatively high chemical stability. In the present study, we hybridized g-C 3 N 4 with sulfur-doped TiO 2 , which is a visible light-responsive photocatalyst with high oxidation ability, in order to improve photocatalytic activity under visible-light irradiation. Hybrid photocatalysts were prepared by three methods: agate mortar, sonication, and planetary mill. Activities of the hybrid photocatalysts depended on the mixing method. The sample prepared by a planetary mill showed the highest photocatalytic activity, 4-times higher than that of sulfur-doped TiO 2 . We concluded that the high activity of the hybridized sample under visible-light irradiation is induced by charge transfer between the two photocatalysts mimicking the Z-scheme in photosynthesis. © 2013.

DOI： 10.1016/j.apcatb.2013.05.042

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Solution-processed amorphous niobium oxide as a novel electron collection layer for inverted polymer solar cells 査読有り

Hamada K., Murakami N., Tsubota T., Ohno T.

Chemical Physics Letters 586 81 - 84 2013年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

Amorphous niobium oxide (NbO x ) as an electron collection layer in inverted polymer solar cells was prepared by a solution process. The power conversion efficiency of inverted polymer solar cells based on a blend of poly(3-hexylthiophene) and[6,6]-phenyl C61 butyric acid methyl ester was improved to 2.22% by inserting an NbO x layer between the active layer and indium tin oxide electrode. An energy level diagram of component materials in the inverted polymer solar cell indicated that the NbO x layer works as both an electron collection layer and hole blocking layer in polymer solar cells. © 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2013.08.015

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Improvement of capacitance value as the electrode of an electrochemical capacitor by mixing starch with guanidine phosphate 査読有り

Toshiki Tsubota,Yoshihoti Miyauchi,Naoya Murakami,Teruhisa Ohno

Journal of Power Sources 196 ( 13 ) 5769 - 5773 2011年04月

Development of a visible-light-responsive photocatalyst by site-selective modification of iron(III) ion on {111} exposed crystal faces of rutile rod 査読有り

N. Murakami,A. Ono,M. Nakamura,T. Tsubota,T. Ohno

APPLIED CATALYSIS B-ENVIRONMENTAL 97 115 - 119 2010年10月

Development of a visible-light-responsive rutile rod by site-selective modification of iron(III) ion on {1 1 1} exposed crystal faces 査読有り

Murakami N., Ono A., Nakamura M., Tsubota T., Ohno T.

Applied Catalysis B: Environmental 97 ( 1-2 ) 115 - 119 2010年06月

記述言語：英語掲載種別：研究論文（学術雑誌）

{1 1 1} exposed crystal faces of shape-controlled rutile titanium(IV) oxide (TiO 2 ) were site-selectively modified with trivalent iron(III) (Fe 3+ ) ions by utilizing adsorption property of iron(III)/iron(II) (Fe 3+ /Fe 2+ ) ions. The rutile TiO 2 with site-selective modification of Fe 3+ ions showed high photocatalytic activity under visible-light irradiation as a result of separation of redox sites, i.e., oxidation and reduction proceed over Fe 3+ ions on {1 1 1} faces and the bare TiO 2 surface on {1 1 0} faces, respectively. Double-beam photoacoustic spectroscopic analyses suggest that the high activity of TiO 2 with site-selective modification of Fe 3+ ions is attributed to not efficient electron injection from Fe 3+ ions but efficient reduction by injected electrons on {1 1 0} faces. © 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apcatb.2010.03.030

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Chemical modification of diamond surface with X-(C6H4)-COOH (X = F, Cl, Br, I) using benzoyl peroxide 査読有り

Toshiki Tsubota,Yuki Kawamura,Naoya Murakami,Teruhisa Ohno

Diamond and Related Materials 19 1003 - 1006 2010年04月

Chemical modification of diamond powder with optically active functionalities and its chiral recognition behavior 査読有り

T. Nakamua,T. Ohana,Y. Hagiwara,T. Tsubota

Applied Surface Science 257 1368 - 1370 2010年04月

Control of the crystal structure of titanium(IV) oxide by hydrothermal treatment of a titanate nanotube under acidic conditions 査読有り

N. Murakami,T. Kamai,T. Tsubota,T. Ohno

CRYSTENGCOMM 12 ( 2 ) 532 - 537 2010年04月

Chemial modification of diamond surface in liquid phase using benzoyl peroxide 査読有り

坪田　敏樹

The 2nd Japan-Korea Joint Symposium on Bio-microsensing Technology 2009年11月

Development of a visible-light-responsive titania nanotube photocatalyst by site-selective modification with hetero metal ions 査読有り

N. Murakami,Y. Fujisawa,T. Tsubota,T. Ohno

APPLIED CATALYSIS B-ENVIRONMENTAL 92 ( 1-2 ) 56 - 60 2009年10月

Effect of heat treatment for activated carbon used as electrode of electric double-layor capacitor 査読有り

坪田　敏樹

Kyutech-KETI workshop to enhance partnership:Development of novel intelligent nano materials 2009年10月

Chemical modification of diamond surface with X-(C6H4)-COOH (X = F, Cl, Br, I) using benzoyl peroxide 査読有り

Toshiki Tsubota,Yuki Kawamura,Naoya Murakami,Teruhisa Ohno

20th European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, and Nitrides 2009年09月

Chemical modification of diamond surface with linoleic acid by using benzoyl peroxide 査読有り

Toshiki Tsubota,Shota Mihara,Naoya Murakami,Teruhisa Ohno

21th European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, and Nitrides 2009年09月

Characterization and photocatalytic performance of carbon nanotube material-modified TiO2 synthesized by using the hot CVD process 査読有り

T. Tsubota,A. Ono,N. Murakami,T. Ohno

APPLIED CATALYSIS B-ENVIRONMENTAL 91 ( 1-2 ) 533 - 538 2009年09月

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