Visible light responsive metal oxide photoanodes for photoelectrochemical water splitting: a comprehensive review on rational materials design

Photoelectrochemical (PEC) water splitting provides a "green" approach for hydrogen production. Photoanodes for water oxidation reactions are the bottleneck for PEC water splitting due to the involved thermodynamic and kinetic challenges. To obtain the target of 10% solar-to-hydrogen (STH) efficiency toward practical applications, efficient photoanodes should be developed. Owing to the intrinsic advantages of low cost, good light harvesting, low toxicity, and excellent (photo)-electrochemical stability, visible light responsive metal oxides such as WO, α-FeO and BiVO have attracted great attention for potential photoanodes and significant achievements have been made in the past decades. In this review, the sate-of-the-art progresses of WO, α-FeO and BiVO photoanodes are summarized with an emphasis on the rational materials design toward efficient PEC water splitting. Moreover, their applications in unassisted PEC water splitting systems are briefly introduced. The perspectives on the challenges and future development of visible light responsive metal oxide photoanodes are presented.