Ligand doping engineering induced robust internal electric field in MOFs/BiVO4 photoanode for water splitting

A robust internal electric field (IEF) within heterojunctions is essential for enhancing the separation and transfer of photogenerated charge carriers during photoelectrochemical (PEC) water splitting. In this contribution, a ligand doping engineering approach is innovatively proposed to design 3,5-Th2-tzH = 3,5-di(thiophen-2-yl)-1H-1,2,4-triazole (CuMTZ)/BiVO4 photoanodes, in which thiophene-containing electron-rich ligands (3,5-Th2-TzH) strengthen the interactions between CuMTZ and BiVO4. This results in the formation of a robust IEF, which serves as a strong driving force for efficient charge carrier transfer and separation, leading to an enhanced photovoltage. Furthermore, the uniform CuMTZ nanolayers act as a cocatalyst that not only increases the number of active reaction sites but also boosts photogenerated holes injection into the electrolyte to participate directly in the water oxidation process. Consequently, CuMTZ/BiVO4 photoanode exhibits a significant 4.26-fold improvement in photocurrent for water oxidation compared to BiVO4. This work highlights the significance of ligand doping engineering in the design of metal-organic framework (MOF)/semiconductor photoanodes for enhancing PEC efficiency.