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285 results on '"Kako, Tetsuya"'

10. Light-Induced Dynamic Restructuring of Cu Active Sites on TiO2 for Low-Temperature H2 Production from Methanol and Water

Author

Luo, Shunqin, primary, Song, Hui, additional, Ichihara, Fumihiko, additional, Oshikiri, Mitsutake, additional, Lu, Wenning, additional, Tang, Dai-Ming, additional, Li, Sijie, additional, Li, Yunxiang, additional, Li, Yifan, additional, Davin, Philo, additional, Kako, Tetsuya, additional, Lin, Huiwen, additional, and Ye, Jinhua, additional

Published
2023
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17. Selective Photo-oxidation of Methane to Methanol with Oxygen over Dual-Cocatalyst-Modified Titanium Dioxide

Author

Song, Hui, Meng, Xianguang, Wang, Shengyao, Zhou, Wei, Song, Shuang, Kako, Tetsuya, and Ye, Jinhua

Subjects
dual cocatalysts, titanium dioxide, methane oxidation, cobalt oxide, nanometals, photocatalysis, methanol
Abstract

Direct and selective oxidation of CH4 with dioxygen to methanol is a "dream reaction" in modern catalysis yet remains a great challenge. Here, we report that TiO2 loaded with dual cocatalysts, that is, nanometals and cobalt oxide (CoOx) nanoclusters, is capable of selectively catalyzing CH4 to CH3OH at room temperature under photoexcitation using abundant and inexpensive O-2 as an oxidant. The best activity for the formation of the primary products, CH3OOH and CH3OH, is up to 50.8 pmol for 2 h with 95% selectivity. Mechanistic studies elucidate that the superior activity and selectivity result from the synergistic effect of nanometals and CoOx. Nanometals enhance CH4 conversion by promoting the separation of the photoexcited electron and the reduction of O-2. The CoOx mediates a mild CH4 oxidation process by suppressing the formation of highly oxidative (OH)-O-center dot radicals that can further oxidize CH3OH to HCHO and CO2, thereby preserving a high selectivity toward oxygenated products. This work provides a prototype in designing efficient photocatalysts for selective oxidation of CH4 to CH3OH with O-2 under mild conditions.

Published
2020

18. Photogenerated Charge Carriers Dynamics on La- and/or Cr-Doped SrTiO3 Nanoparticles Studied by Transient Absorption Spectroscopy

Author

Ichihara, Fumihiko, Sieland, Fabian, Pang, Hong, Philo, Davin, Anh-Thu Duong, Chang, Kun, Kako, Tetsuya, Bahnemann, Detlef W., and Ye, Jinhua

Abstract

Elemental doping into semiconductor-based photocatalysts to narrow the bandgap, thus extending the light absorption to visible light region, is a conventional and widely adopted strategy for water splitting (or artificial photosynthesis) application. However, one critical problem but rarely addressed, is the drastically decreased photocatalytic activity under UV light despite of the increased activity in visible light region, resulting in a decreased total performance under full solar spectrum. In order to elucidate the origin of the commonly observed phenomena, herein we choose La,Cr-codoped SrTiO3 as a proof-of-concept model to probe the effect of dopants on the behavior of photogenerated charge carriers by transient absorption spectroscopy. By observing the excitons, it is found that under UV irradiation, the excitation occurring from the Cr impurity bands limits the excitation of SrTiO3 from valence band, causing the drastic decrease of the photocatalytic activity over doped material. The widely proposed recombination at dopant sites, however, is not dominant for declining the UV light-irradiated performance, especially in the presence of reactant gas (methanol vapor).

Published
2020

19. Light-Induced Dynamic Restructuring of Cu Active Sites on TiO2for Low-Temperature H2Production from Methanol and Water

Author

Luo, Shunqin, Song, Hui, Ichihara, Fumihiko, Oshikiri, Mitsutake, Lu, Wenning, Tang, Dai-Ming, Li, Sijie, Li, Yunxiang, Li, Yifan, Davin, Philo, Kako, Tetsuya, Lin, Huiwen, and Ye, Jinhua

Abstract

The structure and configuration of reaction centers, which dominantly govern the catalytic behaviors, often undergo dynamic transformations under reaction conditions, yet little is known about how to exploit these features to favor the catalytic functions. Here, we demonstrate a facile light activation strategy over a TiO2-supported Cu catalyst to regulate the dynamic restructuring of Cu active sites during low-temperature methanol steam reforming. Under illumination, the thermally deactivated Cu/TiO2undergoes structural restoration from inoperative Cu2O to the originally active metallic Cu caused by photoexcited charge carriers from TiO2, thereby leading to substantially enhanced activity and stability. Given the low-intensity solar irradiation, the optimized Cu/TiO2displays a H2production rate of 1724.1 μmol g–1min–1, outperforming most of the conventional photocatalytic and thermocatalytic processes. Taking advantages of the strong light-matter-reactant interaction, we achieve in situ manipulation of the Cu active sites, suggesting the feasibility for real-time functionalization of catalysts.

Published
2023
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32. Targeted removal of interfacial adventitious carbon towards directional charge delivery to isolated metal sites for efficient photocatalytic H-2 production

Author

Li, Yunxiang, Wang, Shengyao, Wang, Pei, He, Yu, Wang, Xusheng, Chang, Kun, Lin, Huiwen, Ding, Xing, Chen, Hao, Zhang, Hongwei, Izumi, Yasuo, Kako, Tetsuya, 1000090230630, Ye, Jinhua, Li, Yunxiang, Wang, Shengyao, Wang, Pei, He, Yu, Wang, Xusheng, Chang, Kun, Lin, Huiwen, Ding, Xing, Chen, Hao, Zhang, Hongwei, Izumi, Yasuo, Kako, Tetsuya, 1000090230630, and Ye, Jinhua

Abstract

Creation of clean interfaces without contamination of adventitious carbon and robust single active sites are highly desirable for delivery and utilization of electrons in sunlight-driven hydrogen production but still remains challenging in part owing to the lack of understanding in junction nature. Herein, we tackle this challenge by targeted removing of interfacial adventitious carbon between photoharvester CdS and novel single-cobalt co-catalyst (Co-NC). It's found that surface-trapped electrons can readily migrate to the closely attached Co-NC across the cleared interface between CdS and Co-NC. The small-resistance interfacial carrier path and the robust single-cobalt sites work in a cooperative way and hence achieve a superior visible-light driven H-2 generation activity with a rate of 4.34 mmol/h, an apparent quantum yield (AQY) of 63.9% at 400 nm and a ultrahigh turnover frequency (TOF) of up to 16714.7 h(-1). Our finding will motivate future work in creating clean interfaces and unique single active sites for high performance photocatalysis.

Published
2020

47. Crystal-facet-dependent hot-electron transfer in plasmonic-Au/semiconductor heterostructures for efficient solar photocatalysis

Author

Liu, Guigao, Wang, Tao, Zhou, Wei, Meng, Xianguang, Zhang, Huabin, Liu, Huimin, Kako, Tetsuya, and Ye, Jinhua

Abstract

Here, using Au-BiOCl as models, we show the significant crystal facet effects of the semiconductor on hot-electron transfer within such plasmonic heterostructures under visible light. It is found that {010} facets of BiOCl are greatly advantageous over {001} facets for the hot-electron injection, as evidenced by steady-state diffuse reflectance spectroscopy and photoelectrochemical measurements. Consequently, Au-BiOCl-010 exhibits superior activity for photocatalytic aerobic oxidation of 2-propanol with a quantum efficiency of 1.3%, being 3.5 times higher than that of Au-BiOCl-001. The differences in band structure between the {001} and {010} facets of BiOCl may account for the facet-dependent hot-electron transfer characteristics.

Published
2015

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