Photocatalytic Water Splitting for H2 Production via Two‐electron Pathway

Abstract In response to energy and environmental crises, solar‐driven pure water splitting is a promising way to produce and store renewable energy sources without environmental pollution. Photocatalytic water splitting via two‐electron pathway (2H 2 O→H 2 +H 2 O 2 ) is a more kinetically favorable way to produce H 2 compared with traditional four‐electron pathway. Although numerous efforts have been devoted to investigate the application of two‐electron pathway water splitting, drawbacks still inhibit the efficiency of H 2 generation. This review discusses the mechanism and challenges of photocatalytic water splitting via a two‐electron pathway. Then, recent developments in novel photocatalyst preparation and modification strategies for effective H 2 generation via two‐electron pathway were discussed, such as morphology and structure modulation, elemental doping, co‐catalyst loading, and heterostructure construction. In addition, the development of stepwise two‐electron pathway which further decomposed H 2 O 2 and release O 2 was also introduced. Appropriate co‐catalyst with high H 2 O 2 decomposition activity that is essential for stepwise process was discussed. Finally, challenges and opportunities for commercial application of photocatalytic water splitting via two‐electron pathway were briefly outlined.