研究者詳細 - 山方　啓

論文 - 山方　啓

分割表示 227 件中 101 - 120 件目／全件表示 >>

Solar-Driven Photoelectrochemical Water Oxidation over an n-Type Lead-Titanium Oxyfluoride Anode 査読

Naoki Hirayama, Hiroko Nakata, Haruki Wakayama, Shunta Nishioka, Tomoki Kanazawa, Ryutaro Kamata, Yosuke Ebato, Kosaku Kato, Hiromu Kumagai, Akira Yamakata, Kengo Oka, Kazuhiko Maeda

J. Am. Chem. Soc. 141 ( 43 ) 17158 - 17165 2019年10月

Effect of Na-doping on Electron Decay kinetics in SrTiO3 Photocatalyst 査読

Kosaku Kato, Junzhe Jiang, Yoshihisa Sakata, Akira Yamakata

ChemCatChem 11 ( 24 ) 6349 - 6354 2019年10月

Achievement of High Photocatalytic Performance to BaTi4O9 toward Overall H2O Splitting 査読

Yuichi Hiramachi, Hirotaka Fujimori, Akira Yamakata, Yoshihisa Sakata

ChemCatChem 11 ( 24 ) 6213 - 6217 2019年10月

Enhanced water splitting through two-step photoexcitation by sunlight using tantalum/nitrogen-codoped rutile titania as a water oxidation photocatalyst 査読

Shunta Nishioka, Kei-ichi Yanagisawa, Daling Lu, Junie Jhon, M. Vequizo, Akira Yamakata, Koji Kimoto, Miki Inada, Kazuhiko Maeda

Sustainable Energy & Fuels 3 ( 9 ) 2337 - 2346 2019年7月

Enhanced Visible Light Response of TiO<inf>2</inf> Codoped with Cr and Ta Photocatalysts by Electron Doping 査読

Fumiaki Amano, Masashi Nakata, Junie Jhon M. Vequizo, Akira Yamakata

ACS Applied Energy Materials 2 ( 5 ) 3274 - 3282 2019年5月

掲載種別：研究論文（学術雑誌）

© 2019 American Chemical Society. The importance of electron concentration in rutile TiO2 photocatalysts motivated us to apply H2 reduction treatment to visible-light-responsive TiO2 photocatalysts sensitized by chromium ion doping. We found that H2 reduction treatment of rutile TiO2 particles codoped with Ta and Cr (TiO2:Ta/Cr) enhanced photocatalytic activity for O2 evolution by water oxidation under visible irradiation (>2.2 eV). The enhanced visible light activity of H2-treated TiO2:Ta/Cr was attributed to the increase of electron concentration, which was confirmed by UV-vis diffuse reflectance and electron spin resonance (ESR) spectroscopy. The H2-treated TiO2:Ta/Cr photocatalyst was repeatedly used in aqueous media in spite of the presence of doped electrons. Photoluminescence and transient absorption spectroscopies revealed that electron doping with H2 treatment decreased the midgap states working as deep traps of photoexcited electrons and increased the accumulation of the photoexcited electrons in the conduction band. The optimized H2 reduction temperature was decreased with an increase in the amount of higher valence Ta5+ used as a donor-type dopant. This study shows that the precise control of the bulk electronic structure of rutile TiO2 by a combination of codoping and H2 reduction treatment improves the visible-light-driven photocatalytic activity because of the decrease of the trapping sites at deep energy levels and the recombination between deeply trapped electrons and valence band holes.

DOI： 10.1021/acsaem.9b00126

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Construction of Spatial Charge Separation Facets on BaTaO2N Crystals by Flux Growth Approach for Visible-Light-Driven H2 Production 査読

Ying Luo, Sayaka Suzuki, Zheng Wang, Kunio Yubuta, Junie Jhon, M. Vequizo, Akira Yamakata, Hiromasa Shiiba, Takashi Hisatomi, Kazunari Domen, Katsuya Teshima

ACS Applied Materials & Interfaces 11 ( 25 ) 22264 - 22271 2019年5月

Effect of CuFe2O4 ferrite on photocatalysis and carrier dynamics of electrospun α-Fe2O3 nanofibers by time-resolved transient absorption spectroscopy 査読

Pei-Hsuan Hung, Junie Jhon, M. Vequizo, Ren-An Wu, Akira Yamakata, Wenjea J. Tseng

Ceram. Int. 45 ( 12 ) 15676 - 15680 2019年5月

Oxygen-Doped Ta3N5 Nanoparticles for Enhanced Z-Scheme Carbon Dioxide Reduction with a Binuclear Ruthenium(II) Complex under Visible Light 査読

Kanemichi Muraoka, Junie Jhon, M. Vequizo, Ryo Kuriki, Akira Yamakata, Tomoki Uchiyama, Daling Lu, Yoshiharu Uchimoto, Osamu Ishitani, Kazuhiko Maeda

ChemPhotoChem 3 ( 10 ) 1027 - 1033 2019年5月

Improvement of photocatalytic activity under visible-light irradiation by heterojunction of Cu ion loaded WO3 and Cu ion loaded N-TiO2 査読

Tomoya Iihoshi, Takeshi Ohwaki, Junie Jhon, M. Vequizo, Akira Yamakata

Applied Catalysis B: Environmental 248 249 - 254 2019年2月

Sodium titanium oxide bronze nanoparticles synthesized via concurrent reduction and Na+-doping into TiO2(B) 査読

Hasegawa, George, Tanaka, Moeko, Vequizo, Junie Jhon M., Yamakata, Akira, Hojo, Hajime, Kobayashi, Makoto, Kakihana, Masato, Inada, Miki, Akamatsu, Hirofumi, Hayashi, Katsuro

NANOSCALE 11 ( 3 ) 1442 - 1450 2019年1月

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

A mixed valence compound, sodium titanium oxide bronze (NaxTiO2-B), combines intriguing properties of high electric conductivity and good chemical stability together with a unique one-dimensional tunnel crystal structure available for cation storage. However, this compound has not been studied for a long period because of the strongly reductive condition at high temperature required for its preparation, which limits the morphological control such as the preparation of nanocrystals. For the first time in this paper, the topotactic synthesis of nano-sized NaxTiO2-B with high specific surface area (>130 m(2) g(-1)) from TiO2(B) nanoparticles has been demonstrated. The reaction of metastable TiO2(B) with NaBH4 allows carrier electrons to be doped simultaneously with incorporation of Na+ ions into the interstitial sites of the host Ti-O lattice at relatively low temperature. An electrochemical investigation of Li+- and Na+-ion storage behaviors suggests that the incorporated Na+ ions are mainly placed in the 6-fold coordination sites of bronze. In addition, optical measurements including time-resolved transient spectroscopy revealed that the doped electrons in the NaxTiO2-B nanoparticles are predominantly in the Ti3+ state and behave as a small polaron. The pelletized NaxTiO2-B nanoparticles shows a good electronic conductivity of 1.4 x 10(-2) S cm(-1) at 30 degrees C with an activation energy of 0.17 eV, which is attributable to the thermal barrier for the polaron hopping.

DOI： 10.1039/c8nr08372j

Web of Science

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Clear and transparent nanocrystals for infrared-responsive carrier transfer 査読

Sakamoto, M., Kawawaki, T., Kimura, M., Vequizo, J.J.M., Matsunaga, H., Ranasinghe, C.S.K., Yamakata, A., Matsuzaki, H., Furube, A., Teranishi, T.

Nature communications 10 ( 1 ) 406 - 406 2019年

Near infrared light induced plasmonic hot hole transfer at a nano-heterointerface 査読

Zichao Lian, Masanori Sakamoto, Hironori Matsunaga, Junie Jhon M. Vequizo, Akira Yamakata, Mitsutaka Haruta, Hiroki Kurata, Wataru Ota, Tohru Sato, Toshiharu Teranishi

Nature Communications 9 ( 1 ) 2314 - 2314 2018年12月

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

Localized surface plasmon resonance (LSPR)-induced hot-carrier transfer is a key mechanism for achieving artificial photosynthesis using the whole solar spectrum, even including the infrared (IR) region. In contrast to the explosive development of photocatalysts based on the plasmon-induced hot electron transfer, the hole transfer system is still quite immature regardless of its importance, because the mechanism of plasmon-induced hole transfer has remained unclear. Herein, we elucidate LSPR-induced hot hole transfer in CdS/CuS heterostructured nanocrystals (HNCs) using time-resolved IR (TR-IR) spectroscopy. TR-IR spectroscopy enables the direct observation of carrier in a LSPR-excited CdS/CuS HNC. The spectroscopic results provide insight into the novel hole transfer mechanism, named plasmon-induced transit carrier transfer (PITCT), with high quantum yields (19%) and long-lived charge separations (9.2 μs). As an ultrafast charge recombination is a major drawback of all plasmonic energy conversion systems, we anticipate that PITCT will break the limit of conventional plasmon-induced energy conversion.

DOI： 10.1038/s41467-018-04630-w

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Plasmonic p–n Junction for Infrared Light to Chemical Energy Conversion 査読

Zichao Lian, Masanori Sakamoto, Junie Jhon, M. Vequizo, Chandana Sampath, Kumara Ranasinghe, Akira Yamakata, Takuro Nagai, Koji Kimoto, Yoichi Kobayashi, Naoto Tamai, Toshiharu Teranishi

J. Am. Chem. Soc. 141 ( 6 ) 2446 - 2450 2018年12月

Curious Behaviors of Photogenerated Electrons and Holes at the Defects on Anatase, Rutile, and Brookite TiO2 Powders: A Review 招待査読

Akira Yamakata, Junie Jhon, M. Vequizo

J. Photochem. Photobiol. C-Photochem. 40 234 - 243 2018年12月

Expansion of the photoresponse window of a BiVO4 photocatalyst by doping with chromium(VI) 査読

Kazuya Okuno, Hideki Kato, Junie Jhon, M. Vequizo, Akira Yamakata, Hisayoshi Kobayashi, Makoto Kobayashi, Masato Kakihana

RSC Advances 8 ( 67 ) 38140 - 38145 2018年11月

A Copolymerization Approach to Improving Ru(II)-Complex/C3N4 Hybrid Photocatalysts for Visible-Light CO2 Reduction 査読

Constantine Tsounis, Ryo Kuriki, Kengo Shibata, Junie Jhon, M. Vequizo, Daling Lu, Akira Yamakata, Osamu Ishitani, Rose Amal, Kazuhiko Maeda

ACS Sustainable Chemistry & Engineering 6 ( 11 ) 15333 - 15340 2018年10月

Effects of Interfacial Electron Transfer in Metal Complex−Semiconductor Hybrid Photocatalysts on Z‑Scheme CO2 Reduction under Visible Light 査読

Akinobu Nakada, Ryo Kuriki, Keita Sekizawa, Shunta Nishioka, Junie Jhon, M. Vequizo, Tomoki Uchiyama, Nozomi Kawakami, Daling Lu, Akira Yamakata, Yoshiharu Uchimoto, Osamu Ishitani, Kazuhiko Maeda

ACS Catalysis 8 ( 10 ) 9744 - 9754 2018年9月

Undoped Layered Perovskite Oxynitride Li2 LaTa2 O6 N for Photocatalytic CO2 Reduction with Visible Light. 査読国際誌

Takayoshi Oshima, Tom Ichibha, Ken Sinkou Qin, Kanemichi Muraoka, Junie Jhon M Vequizo, Keisuke Hibino, Ryo Kuriki, Shunsuke Yamashita, Kenta Hongo, Tomoki Uchiyama, Kotaro Fujii, Daling Lu, Ryo Maezono, Akira Yamakata, Hideki Kato, Koji Kimoto, Masatomo Yashima, Yoshiharu Uchimoto, Masato Kakihana, Osamu Ishitani, Hiroshi Kageyama, Kazuhiko Maeda

Angewandte Chemie (International ed. in English) 57 ( 27 ) 8154 - 8158 2018年7月

記述言語：英語掲載種別：研究論文（学術雑誌）

Oxynitrides are promising visible-light-responsive photocatalysts, but their structures are almost confined with three-dimensional (3D) structures such as perovskites. A phase-pure Li2 LaTa2 O6 N with a layered perovskite structure was successfully prepared by thermal ammonolysis of a lithium-rich oxide precursor. Li2 LaTa2 O6 N exhibited high crystallinity and visible-light absorption up to 500 nm. As opposed to well-known 3D oxynitride perovskites, Li2 LaTa2 O6 N supported by a binuclear RuII complex was capable of stably and selectively converting CO2 into formate under visible light (λ>400 nm). Transient absorption spectroscopy indicated that, as compared to 3D oxynitrides, Li2 LaTa2 O6 N possesses a lower density of mid-gap states that work as recombination centers of photogenerated electron/hole pairs, but a higher density of reactive electrons, which is responsible for the higher photocatalytic performance of this layered oxynitride.

DOI： 10.1002/anie.201803931

PubMed

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Binary flux-promoted formation of trigonal ZnIn2S4 layered crystals using ZnS-containing industrial waste and their photocatalytic performance for H2 production 査読

Mirabbos Hojamberdiev, Yanfei Cai, Junie Jhon, M. Vequizo, Mohammad Mansoob Khan, Ronald Vargas, Kunio Yubuta, Akira Yamakata, Katsuya Teshima, Masashi Hasegawa

Green Chemistry 20 ( 16 ) 3845 - 3856 2018年7月

Enhanced photocatalytic NOx decomposition of visible-light responsive F-TiO2/(N,C)-TiO2 by charge transfer between F-TiO2 and (N,C)-TiO2through their doping levels 査読

Shio Komatsuda, Yusuke Asakura, Junie Jhon, M. Vequizo, Akira Yamakata, Shu Yin

Appl. Catal. B-Environ. 238 358 - 364 2018年7月

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