Advances in engineering perovskite oxides for photochemical and photoelectrochemical water splitting

Solar-driven water splitting is an efficient process for converting solar energy into chemical energy. In this process, semiconductor materials are excited by solar energy to generate free electrons to participate in the water-splitting reaction. Among these semiconductor materials, inorganic perovskite oxides have a spatial structure that is easy to control and thereby lead to different energy band structures and photocatalytic properties. More importantly, perovskite oxides can be compounded with other organic/inorganic materials to promote charge separation and improve apparent quantum yield. However, the low solar-to-hydrogen conversion efficiency has not yet reached the requirements of practical applications. In this review, the fundamental principles of solar-driven water splitting based on perovskite materials are introduced according to the most recently published results. In addition, the innovative modification techniques for water splitting based on perovskite oxides have been summarized, focusing on the following methods: element doping, homo/heterojunction formation, Z-scheme, plasmon effect, dye sensitization, carbon enhancement, and surface modifications. Note that the applications in the visible light wavelength range have been described, with emphasis among all these modification materials. Furthermore, the recent water-splitting reaction systems for practical applications are briefly discussed. As a summary, we outline the challenges and potential utilization associated with visible light–driven water splitting based on perovskite oxides for future commercial applications. This review describes various modification methods to improve photochemical performance of perovskite oxides as well as illustrates the potential to employ perovskite oxides as a key material for the practical application of water splitting.