Effective charge transfer regulation for robust photoelectrochemical water splitting

The direct conversion of solar energy to chemical fuels is an important approach to address the world's challenges of sustainable energy, environmental and climate issues owing to the abundant solar energy. Photoectrochemical (PEC) cells as a promising technology by the utilization of solar energy have received much attention for the generation of renewable hydrogen from water splitting on a large scale. However, the efficiency of solar energy conversion into hydrogen is still limited by narrow light absorption, slow charge transfer and sluggish surface reaction kinetics. Great efforts in the regulation of charge transfer have been summarized toward efficient solar-to-chemical energy conversion in this review. Firstly, various photoanodes and photocathodes are been discussed. Then, different strategies such as morphological regulation, heteroatom and defect introduction, heterostructure engineering and cocatalyst incorporation are elaborated to accelerate the charge transfer process and optimize the PEC performance. Finally, the perspectives and comprehensive outlooks on the future regulation of charge transfer are also proposed. This review offers an overview for the rational design and development of the promising photoelectrodes and the delicate manipulation of photogenerated charge transfer in PEC systems for effective solar-to-chemical energy conversion.