State-of-the-art advancements of transition metal oxides as photoelectrode materials for solar water splitting

Photoelectrochemical (PEC) water splitting can convert renewable solar energy into clean hydrogen fuel. Photoelectrodes are the core components of water-splitting cells. In the past 40 years, a series of binary and ternary transition metal oxides have been investigated as photoelectrode materials for solar water splitting, and numerous studies have been carried out to modify their water-splitting performances. Although satisfactory transition metal oxide photoelectrode materials have not been found, it is necessary to summarize the recent advancements in transition metal oxide photoelectrode materials to guide future research. In this review, the background and principle of PEC water splitting are introduced. The semiconductor properties and modification progress of typical binary and ternary metal oxide photoanodes and photocathodes for solar water splitting are summarized. Based on the newly developed strategies in recent years, a brief outlook is presented for efficient PEC water splitting using transition metal oxide photoelectrodes.