Boosting charge separation of BiVO4 photoanode modified with 2D metal-organic frameworks nanosheets for high-performance photoelectrochemical water splitting

Water splitting by photoelectrochemical (PEC) processes to convert solar energy into hydrogen energy using semiconductors is regarded as one of the most ideal methods to solve the current energy crisis and has attracted widespread attention. Herein, Co-based metal-organic framework (Co(bpdc)(H2O)4 (Co-MOF) nanosheets as passivation layers were in-situ constructed on the surface of BiVO4 films through an uncomplicated hydrothermal method (Co-MOF/BiVO4). Under AM 1.5G illumination, synthesized Co-MOF/BiVO4 electrode exhibited a 4-fold higher photocurrent than bare BiVO4, measuring 6.0 mA/cm2 at 1.23 V vs. RHE in 1 mol/L potassium borate electrolyte (pH 9.5) solution. Moreover, the Co-MOF/BiVO4 film demonstrated a 96% charge separation efficiency, a result caused by an inhibited recombination rate of photogenerated electrons and holes by the addition of Co-MOF nanosheets. This work provides an idea for depositing inexpensive 2D Co-MOF nanosheets on the photoanode as an excellent passivation layer for solar fuel production.