Surface Modification of CoOx Loaded BiVO4 Photoanodes with Ultrathin p-Type NiO Layers for Improved Solar Water Oxidation

• DOI: 10.1021/jacs.5b00256
• Publication Date: 2015-03-24T17:16:23Z
• Authors: Miao Zhong; Takashi Hisatomi; Yongbo Kuang; Jiao Zhao; Min Liu; Akihide Iwase; Qingxin Jia; Hiroshi Nishiyama; Tsutomu Minegishi; Mamiko Nakabayashi; Naoya Shibata; Ryo Niishiro; Chisato Katayama; Hidetaka Shibano; Masao Katayama; Akihiko Kudo; Taro Yamada; Kazunari Domen
• Keywords: Non-blocking I/O; Photocurrent; Photoelectrochemical cell; Solar fuel; Photoelectrochemistry

Photoelectrochemical (PEC) devices that use semiconductors to absorb solar light for water splitting offer a promising way toward the future scalable production of renewable hydrogen fuels. However, charge recombination in photoanode/electrolyte (solid/liquid) junction is major energy loss and hampers PEC performance from being efficient. Here, we show this problem addressed by conformal deposition an ultrathin p-type NiO layer on photoanode create buried p/n as well reduce at surface trapping states enlarged band bending. Further, situ formed hydroxyl-rich hydroxyl-ion-permeable NiOOH enables dual catalysts CoO(x) improved oxidation activity. Compared loaded BiVO4 (CoO(x)/BiVO4) photoanode, ∼6 nm deposited NiO/CoO(x)/BiVO4 triples photocurrent density 0.6 V(RHE) under AM 1.5G illumination 1.5% half-cell solar-to-hydrogen efficiency. Stoichiometric oxygen are generated with Faraday efficiency unity over 12 h. This strategy could be applied other narrow gap semiconducting photoanodes low-cost fuel generation devices.