Self-improvement of solar water oxidation for the continuously-irradiated hematite photoanode

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 48; no. 4; pp. 15151 - 15159
• Main Authors: Zhou, Zhongyuan, Wu, Shaolong, Xiao, Chenhong, Li, Liujing, Shao, Weijia, Ding, Hao, Wen, Long, Li, Xiaofeng
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 14.10.2019
• Subjects: Carrier recombination; Electrical properties; Electrical resistivity; Hematite; Irradiation; Oxidation; Performance enhancement; Photoanodes; Photoelectric effect; Photoelectric emission; Titanium dioxide
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c9dt03368h

Improving bulk- or surface-properties has been found as an effective route to regulate and enhance the photoelectrochemical (PEC) performances of some metal-oxide photoelectrodes. However, both bulk and surface self-improvement resulting from the photocharging (PC) effect is rarely reported and as a result the underlying mechanism of the PC effect is not fully understood. Here, we demonstrate that the hematite photoanode integrated with Sn doping and a TiO 2 underlayer shows a substantial increase in the photocurrent density ( i.e. , from 0.69 to 1.12 mA cm −2 at 1.23 V relative to the standard hydrogen electrode) and a cathodic shift of the onset potential after being irradiated by a one-sun simulator for 12 h. The primary reasons for these can be categorized into two fundamental factors: (1) the enhanced bulk conductivity and the resulting decrease in carrier bulk recombination from the gradually increasing ratio of Fe 2+ and Fe 3+ ; (2) the reduced carrier surface recombination from the photogenerated passivation layer. Ultimately, both the bulk and surface electrical properties of the hematite photoanode are substantially self-improved under continuous irradiation. This work deepens the understanding of the PC effect and proves that it is a promising technique for the PEC-performance enhancement of the hematite photoanode. Both the bulk and surface electrical properties of the α-Fe 2 O 3 photoanode are obviously self-improved under continuous irradiation.