Semiconductor-based Photoanodes Modified with Metal-Organic Frameworks and Molecular Catalysts as Cocatalysts for Enhanced Photoelectrochemical Water Oxidation Reaction

Photoelectrochemical (PEC) water splitting is a promising approach to convert inexhaustible solar energy to hydrogen energy. In this system, the semiconductor is a crucial part as photoelectrode to harvest the solar light and achieve water splitting on the surface. For the surface modification of semiconductor, cocatalyst loading is an effective method to improve the sluggish reaction kinetics. Due to the specific structure of their organic ligands, the metal-organic frameworks (MOFs) or molecular catalysts as cocatalysts can provide more reaction sites and overcome the interface recombination between semiconductors and cocatalyst layers. The inorganic metal species derived from the MOFs or molecular catalysts also possess porous structures. This review summarizes the recent developments of MOFs and molecular catalysts as well as their derivatives modifying several representative semiconductors for PEC water oxidation reaction. The synthesis methods and performance enhancements are discussed. Finally, this review addresses remarks on current existing changes and perspectives for the further development.