Enhancement of Charge Separation and Hydrogen Evolution on Particulate La5Ti2CuS5O7 Photocathodes by Surface Modification

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• 作者：Jingyuan Liu ; Takashi HisatomiDharmapura H. K. Murthy ; Miao Zhong ; Mamiko Nakabayashi ; Tomohiro Higashi ; Yohichi Suzuki ; Hiroyuki Matsuzaki ; Kazuhiko Seki ; Akihiro Furube ; Naoya Shibata ; Masao Katayama ; Tsutomu Minegishi ; Kazunari Domen
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2017
• 出版时间：January 19, 2017
• 年：2017
• 卷：8
• 期：2
• 页码：375-379
• 全文大小：355K
• ISSN：1948-7185

文摘

Particulate La₅Ti₂CuS₅O₇ (LTC) photocathodes prepared by particle transfer show a positive onset potential of 0.9 V vs RHE for the photocathodic current in photoelectrochemical (PEC) H₂ evolution. However, the low photocathodic current imposes a ceiling on the solar-to-hydrogen energy conversion efficiency of PEC cells based on LTC photocathodes. To improve the photocurrent, in this work, the surface of Mg-doped LTC photocathodes was modified with TiO₂, Nb₂O₅, and Ta₂O₅ by radio frequency reactive magnetron sputtering. The photocurrent of the modified Mg-doped LTC photocathodes was doubled because these oxides formed type-II heterojunctions and extended the lifetimes of photogenerated charge carriers. The enhanced photocathodic current was attributed to hydrogen evolution at a positive potential of +0.7 V vs RHE. This work opens up possibilities for improving PEC hydrogen evolution on particulate photocathodes based on surface oxide modifications and also highlights the importance of the band gap alignment.