Faculty Profiles - Yamakata Akira

Papers - Yamakata Akira

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Photocatalytic Hydrogen Evolution Activity of Nitrogen/Fluorine-Codoped Rutile TiO₂ Reviewed

Akinobu Miyoshi, Megumi Okazaki, Kosaku Kato, Tomoki Kanazawa, Toshiyuki Yokoi, Shunta Nishioka, Shunsuke Nozawa, Akira Yamakata, Kazuhiko Maeda

ACS Omega 8 ( 44 ) 41809 - 41815 2023.10

In situ surface-enhanced infrared absorption analysis of the excited carrier transfer from n-type Si photoelectrode to Pt oxygen evolution cocatalyst by probing adsorbed CO molecules Reviewed

Shu Ashimura, Reiya Konaka, Taki Suginaga, Kazuki Harada, Akira Yamakata, Chechia Hu, Hepsiba Niruba Catherine, Ke-Hsuan Wang, Takeshi Kawai, Masaaki Yoshida

Journal of the Taiwan Institute of Chemical Engineers 105121 - 105121 2023.9

Unfolding the Impact of H<inf>2</inf>-Reduction Treatment in Enhancing the Photocatalytic Activity of Rutile TiO<inf>2</inf> Based on Photocarriers Dynamics Invited Reviewed

Junie Jhon M. Vequizo, Kosaku Kato, Fumiaki Amano, Akira Yamakata

Journal of Physical Chemistry C 127 ( 22 ) 10411 - 10418 2023.6

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

In the pursuit of efficient titania photocatalysts for water splitting, several strategies have been employed. One of these is reduction of titania (TiO2) via treatment under hydrogen atmosphere, a promising technique to improve the photocatalytic performance. It has been proposed that electron injection induced by reduction on TiO2 demonstrated an improved photocatalytic activity. However, the dynamical processes involving the photogenerated charge carriers in reduced TiO2 have not been fully explored and understood yet. In this work, we employ time-resolved absorption spectroscopy (TAS) and photoluminescence (PL) measurements to unravel the impact of H2 reduction treatment on the photocarriers in rutile TiO2 (R-TiO2). TAS results revealed that the photoexcited electrons are preferentially filling the shallower trap states of reduced R-TiO2, with the lowest energy limit of ∼0.25 eV below the conduction band minimum, much shallower than that of nonreduced R-TiO2 (∼0.62 eV). Furthermore, these favorable effects of H2-reduction resulted in notable increase of long-lived shallow-trapped electrons, substantially extending the lifetimes of electrons and holes. PL measurements strongly support the positive impact of H2 reduction treatment: the NIR emission (∼850 nm) is largely quenched, indicating that the radiative recombination of deep trapped electrons and holes is significantly reduced. The combined PL and TAS results shed light on the impact of H2 reduction on R-TiO2, and this strategy can be potentially useful for further development of other photocatalytic materials.

DOI： 10.1021/acs.jpcc.3c00855

Scopus

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Metal Single‐Atom Cocatalyst on Carbon Nitride for the Photocatalytic Hydrogen Evolution Reaction: Effects of Metal Species Reviewed

Yuki Akinaga, Tokuhisa Kawawaki, Hinano Kameko, Yuki Yamazaki, Kenji Yamazaki, Yuhi Nakayasu, Kosaku Kato, Yuto Tanaka, Adie Tri Hanindriyo, Makito Takagi, Tomomi Shimazaki, Masanori Tachikawa, Akira Yamakata, Yuichi Negishi

Advanced Functional Materials 33 ( 33 ) 2023.5

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

Abstract

Single‐atom (SA) catalysts exhibit high activity in various reactions because there are no inactive internal atoms. Accordingly, SA cocatalysts are also an active research fields regarding photocatalytic hydrogen (H₂) evolution which can be generated by abundant water and sunlight. Herein, it is investigated whether 10 transition metal elements can work as an SA on graphitic carbon nitride (g‐C₃N₄; i.e., gCN), a promising visible‐light‐driven photocatalyst. A method is established to prepare SA‐loaded gCN at high loadings (weight of ≈3 wt.% for Cu, Ni, Pd, Pt, Rh, and Ru) by modulating the photoreduction power. Regarding Au and Ag, SAs are formed with difficulty without aggregation because of the low binding energy between gCN and the SA. An evaluation of the photocatalytic H₂‐evolution activity of the prepared metal SA‐loaded gCN reveals that Pd, Pt, and Rh SA‐loaded gCN exhibits relatively high H₂‐evolution efficiency per SA. Transient absorption spectroscopy and electrochemical measurements reveal the following: i) Pd SA‐loaded gCN exhibits a particularly suitable electronic structure for proton adsorption and ii) therefore they exhibit the highest H₂‐evolution efficiency per SA than other metal SA‐loaded gCN. Finally, the 8.6 times higher H₂‐evolution rate per active site of Pd SA is achieved than that of Pd‐nanoparticles cocatalyst.

DOI： 10.1002/adfm.202303321

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Improved Photocatalytic O2 Evolution on a Sillén–Aurivillius Perovskite Oxychloride Bi6NbWO14Cl by Rh2O3 Additives and Surface Modifications Invited Reviewed

Hajime Suzuki, Takanori Takashima, Osamu Tomita, Tomoki Kanazawa, Shunsuke Nozawa, Kosaku Kato, Akira Yamakata, Kouichi Nakashima, Akinori Saeki, Ryu Abe

The Journal of Physical Chemistry C 127 ( 17 ) 7965 - 7973 2023.5

Co-doping of a La5Ti2Cu0.9Ag0.1O7S5 photocatalyst (λ < 700 nm) with Ga and Al to enhance photocatalytic H2 evolution Reviewed International journal

Xiaojun Wang, Zhenhua Pan, Junie Jhon, M. Vequizo, Takashi Hisatomi, Swarnava Nandy, Tomohiro Higashi, Lihua Lin, Jiadong Xiao, Tsuyoshi Takata, Akira Yamakata, Wei Yan, Kazunari Domen

Chemical communications (Cambridge, England) 59 ( 45 ) 6913 - 6916 2023.5

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

La5Ti2Cu0.9Ag0.1O7S5 (LTCA) (λ < 700 nm) can function as a photocatalyst for H2 evolution. Co-doping LTCA with Ga3+ and Al3+ at Ti4+ sites effectively enhanced the H2 evolution activity of LTCA, yielding an apparent quantum efficiency of 18% at 420 nm. The activity of this material was greater than that previously reported for Ga-doped LTCA by a factor of 1.6. Such activity enhancement is attributed to increasing the population of long-lived photogenerated electrons and facilitating the electron transfer to the cocatalyst. This work significantly improved the LTCA-based photocatalyst for H2 evolution, making it a promising material for future application in non-sacrificial Z-scheme water splitting.

DOI： 10.1039/D3CC01863F

PubMed

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Carbon Nitride Loaded with an Ultrafine, Monodisperse, Metallic Platinum‐Cluster Cocatalyst for the Photocatalytic Hydrogen‐Evolution Reaction Reviewed

Daichi Yazaki, Tokuhisa Kawawaki, Daisuke Hirayama, Masanobu Kawachi, Kosaku Kato, Sota Oguchi, Yuichi Yamaguchi, Soichi Kikkawa, Yoshiya Ueki, Sakiat Hossain, D. J. Osborn, Fumihiko Ozaki, Shunsuke Tanaka, Jun Yoshinobu, Gregory F. Metha, Seiji Yamazoe, Akihiko Kudo, Akira Yamakata, Yuichi Negishi

Small 19 ( 34 ) 2208287 2023.4

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

Abstract

For the realization of a next‐generation energy society, further improvement in the activity of water‐splitting photocatalysts is essential. Platinum (Pt) is predicted to be the most effective cocatalyst for hydrogen evolution from water. However, when the number of active sites is increased by decreasing the particle size, the Pt cocatalyst is easily oxidized and thereby loses its activity. In this study, a method to load ultrafine, monodisperse, metallic Pt nanoclusters (NCs) on graphitic carbon nitride is developed, which is a promising visible‐light‐driven photocatalyst. In this photocatalyst, a part of the surface of the Pt NCs is protected by sulfur atoms, preventing oxidation. Consequently, the hydrogen‐evolution activity per loading weight of Pt cocatalyst is significantly improved, 53 times, compared with that of a Pt‐cocatalyst loaded photocatalyst by the conventional method. The developed method is also effective to enhance the overall water‐splitting activity of other advanced photocatalysts such as SrTiO₃ and BaLa₄Ti₄O₁₅.

DOI： 10.1002/smll.202208287

Scopus

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Synthesis of crystal-phase and color tunable mixed anion co-doped titanium oxides and their controllable photocatalytic activity Reviewed

Jingdi Cao, Takuya Hhasegawa, Yusuke Asakura, Akira Yamakata, Peng Sun, Wenbin Cao, Shu Yin

International Journal of Minerals, Metallurgy and Materials 30 ( 10 ) 2036 - 2043 2023.4

Asymmetrically coordinated cobalt single atom on carbon nitride for highly selective photocatalytic oxidation of CH4 to CH3OH Reviewed

Jie Ding, Zhenyuan Teng, Xiaozhi Su, Kosaku Kato, Yuhang Liu, Ting Xiao, Wei Liu, Lingyue Liu, Qiao Zhang, Xinyi Ren, Jincheng Zhang, Zhaoyang Chen, Ohno Teruhisa, Akira Yamakata, Hongbin Yang, Yanqiang Huang, Bin Liu, Yueming Zhai

Chem 9 ( 4 ) 1017 - 1035 2023.4

Surface-Specific Modification of Graphitic Carbon Nitride by Plasma for Enhanced Durability and Selectivity of Photocatalytic CO2 Reduction with a Supramolecular Photocatalyst Reviewed

Noritaka Sakakibara, Mitsuhiko Shizuno, Tomoki Kanazawa, Kosaku Kato, Akira Yamakata, Shunsuke Nozawa, Tsuyohito Ito, Kazuo Terashima, Kazuhiko Maeda, Yusuke Tamaki, Osamu Ishitani

ACS Applied Materials & Interfaces 15 13025 - 13218 2023.3

Particle Size Dependent Trap States of Photoexcited Carriers in Anatase TiO2 Nanoparticles Invited Reviewed

Shimpei Naniwa, Kosaku Kato, Akira Yamamoto, Hisao Yoshida, Akira Yamakata

The Journal of Physical Chemistry C 127 ( 8 ) 4295 - 4302 2023.3

Promoted Utilization of Charge Carriers in La₅Ti₂Cu_0.9Ag_0.1O₇S₅-Based Photocatalyst Sheets for Efficient Z-Scheme Overall Water Splitting Reviewed

Shanshan Chen, Swarnava Nandy, Junie Jhon M. Vequizo, Takashi Hisatomi, Mamiko Nakabayashi, Zhenhua Pan, Qi Xiao, Zheng Wang, Lihua Lin, Song Sun, Kosaku Kato, Akira Yamakata, Naoya Shibata, Tsuyoshi Takata, Fuxiang Zhang, Kazunari Domen

ACS Catalysis 13 ( 5 ) 3285 - 3294 2023.2

Overall Water Splitting by a SrTaO₂N-Based Photocatalyst Decorated with an Ir-Promoted Ru-Based Cocatalyst Reviewed

Kaihong Chen, Jiadong Xiao, Junie Jhon M. Vequizo, Takashi Hisatomi, Yiwen Ma, Mamiko Nakabayashi, Tsuyoshi Takata, Akira Yamakata, Naoya Shibata, Kazunari Domen

Journal of the American Chemical Society 145 ( 7 ) 3839 - 3843 2023.1

Zr-doped BaTaO₂N photocatalyst modified with Na–Pt cocatalyst for efficient hydrogen evolution and Z-scheme water splitting Reviewed

Huihui Li, Junie Jhon M. Vequizo, Takashi Hisatomi, Mamiko Nakabayashi, Jiadong Xiao, Xiaoping Tao, Zhenhua Pan, Wenpeng Li, Shanshan Chen, Zheng Wang, Naoya Shibata, Akira Yamakata, Tsuyoshi Takata, Kazunari Domen

EES Catalysis 1 26 - 35 2023.1

Active BaTaO2N Photocatalysts Prepared from Amorphous Ta2O5 Precursor for Overall Water Splitting under Visible Light Reviewed

Shinji Nishimae, Junie Jhon M. Vequizo, Yasunobu Inoue, Akira Yamakata, Mamiko Nakabayashi, Tomohiro Higashi, Kazunari Domen

Journal of Materials Chemistry A 11 6299 - 6310 2023

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

Barium tantalum oxynitride (BaTaO2N), a photocatalyst active during one-step-excitation overall water splitting under visible light, was synthesized by NH3-based nitridation of a mixture of BaCO3 and amorphous Ta2O53H2O. H2 and...

DOI： 10.1039/d2ta10010j

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An unexplored role of the CrO_x shell in an elaborated Rh/CrO_x core–shell cocatalyst for photocatalytic water splitting: a selective electron transport pathway from semiconductors to core metals, boosting charge separation and H₂ evolution Reviewed

Tetsu Kotani, Kanta Ogawa, Hajime Suzuki, Kosaku Kato, Osamu Tomita, Akira Yamakata, Ryu Abe

EES Catalysis 1 ( 3 ) 255 - 262 2023

An emissive charge-transfer excited-state at the well-defined hetero-nanostructure interface of an organic conjugated molecule and two-dimensional inorganic nanosheet Reviewed

Tomokazu Umeyama, Daizu Mizutani, Yuki Ikeda, W. Ryan Osterloh, Futa Yamamoto, Kosaku Kato, Akira Yamakata, Masahiro Higashi, Takumi Urakami, Hirofumi Sato, Hiroshi Imahori

Chemical Science 14 ( 42 ) 11914 - 11923 2023

A general interfacial-energetics-tuning strategy for enhanced artificial photosynthesis Reviewed

Tian Liu, Zhenhua Pan, Kosaku Kato, Junie Jhon M. Vequizo, Rito Yanagi, Xiaoshan Zheng, Weilai Yu, Akira Yamakata, Baoliang Chen, Shu Hu, Kenji Katayama, Chiheng Chu

Nature Communications 13 ( 1 ) 7783 2022.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

The demands for cost-effective solar fuels have triggered extensive research in artificial photosynthesis, yet the efforts in designing high-performance particulate photocatalysts are largely impeded by inefficient charge separation. Because charge separation in a particulate photocatalyst is driven by asymmetric interfacial energetics between its reduction and oxidation sites, enhancing this process demands nanoscale tuning of interfacial energetics on the prerequisite of not impairing the kinetics and selectivity for surface reactions. In this study, we realize this target with a general strategy involving the application of a core/shell type cocatalyst that is demonstrated on various photocatalytic systems. The promising H₂O₂ generation efficiency validate our perspective on tuning interfacial energetics for enhanced charge separation and photosynthesis performance. Particularly, this strategy is highlighted on a BiVO₄ system for overall H₂O₂ photosynthesis with a solar-to-H₂O₂ conversion of 0.73%.

DOI： 10.1038/s41467-022-35502-z

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Other Link： https://www.nature.com/articles/s41467-022-35502-z

Harnessing infrared solar energy with plasmonic energy upconversion (Oct, 10.1038/s41893-022-01015-2, 2022) Reviewed

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

NATURE SUSTAINABILITY 5 1092 - 1099 2022.11

Effects of Hydroxy Groups in Anthraquinone Dyes on Photocatalytic Activity of Visible-light-sensitized Pt-TiO2 for Hydrogen Evolution Reviewed

Fumiaki Amano, Yasukazu Akaki, Akira Yamakata

Catalysis Surveys from Asia 27 ( 1 ) 75 - 83 2022.10

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Papers - Yamakata Akira