Interfacial Engineering-Assisted Energy Level Modulation Enhances the Photoelectrochemical Water Oxidation Performance of Bismuth Vanadate Photoanodes

BiVO₄ faces significant challenges for widespread application in photoelectrochemical (PEC) water oxidation due to its poor hole transport ability, high surface defect density, and sluggish water oxidation reaction kinetics. Employing interfacial engineering to assist in energy level modulation is an effective strategy to address these challenges. Herein, a CuCrO₂ hole transport layer (HTL) is coupled and further grew NiCo-MOF in situ to prepare a NiCo-MOF-CuCrO₂-BiVO₄ composite photoanode. The novel composite photoanode not only achieves a photocurrent density of 5.75 mA cm⁻² at 1.23 V versus a reversible hydrogen electrode (vs RHE) but also maintains stable operation for over 24 h. Comprehensive physicochemical characterization and density-functional theory calculations confirm that the built-in electric field generated by the p–n heterojunction formed between the CuCrO₂ HTL and BiVO₄ photoanode enhances the hole transport ability. Moreover, the NiCo-MOF chelated on the photoanode surface not only passivates the surface defect states but also accelerates the kinetics of the water oxidation reaction. Under the synergistic effect of dual modification, the PEC water oxidation performance of the BiVO₄ photoanode is dramatically improved. This pioneering work presents a MOF/HTL/BiVO₄ configuration that provides a blueprint for the future development of integrated photoanodes for efficient solar energy conversion.