Defect engineering of the protection layer for photoelectrochemical devices

Photoelectrochemical (PEC) device integrated by solar absorber and catalyst is an economically viable solution for storing the solar energy into the fuel, synthesizing the chemical production, and purifying the environment. However, the degradation of semiconductor-based photoelectrodes during PEC reactions is one of the largest limitations for the application of PEC devices. Facing this challenge, the most prevailing strategy is to construct the protection layer on the surface of semiconductor for insulating the semiconductor from the electrolyte. The development of defect engineering in the protection layer is used to further addresses the issues from the introduction of new layer, including light transmission, charge transfer, interfacial recombination and surface activity. This review aims to discuss recent advances in the defect engineering of protection layer for PEC devices. The types, characterization, role and utilization of the defects in the protection layer are discussed and summarized. Finally, the critical challenges and future perspective towards the development of the defect engineering of protection layer for PEC devices are analyzed.