Photocatalytic Water Splitting for H2 Production via Two‐electron Pathway

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 (2H2O→H2+H2O2) is a more kinetically favorable way to produce H2 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 H2 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 H2 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 H2O2 and release O2 was also introduced. Appropriate co‐catalyst with high H2O2 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.