Construction of BiOBr/BiVO4 S-scheme heterojunctions photocatalyst for efficient oxygen evolution from water splitting

Semiconductor photocatalytic oxygen evolution via water splitting is one of the most effective ways to address energy and environmental challenges. However, rapid recombination of photogenerated electrons and holes limits the performance of single photocatalysts. Herein, we employed a facile alcoholysis-calcination method to synthesize BiOBr/BiVO 4 S-scheme heterojunction photocatalysts through the in situ conversion of BiOBr. This preparation method ensures intimate contact between BiOBr and BiVO 4 , establishing an electronic transfer channel that reduces the charge transfer distance and enhances charge transfer capabilities. Simultaneously, we used density functional theory (DFT) calculations and in situ X-ray photoelectron spectroscopy (XPS) to analyze charge transfer behavior. The results show that the S-scheme heterojunction promotes photogenerated electrons to transfer from the conduction band (CB) of BiVO 4 to the valence band (VB) of BiOBr. This transfer process facilitates efficient charge separation and enhances the system’s redox capabilities. Under simulated sunlight irradiation, the BiOBr/BiVO 4 photocatalyst exhibits excellent photocatalytic oxygen evolution activity, with a rate of 266.38 μmol·g -1 ·h -1 and a photocurrent density of 1.8 μA·cm⁻². This corresponds to a 1.60-fold enhancement over pristine BiOBr and a 2.20-fold increase relative to BiVO 4 . Finally, the possible reaction mechanism has also been discussed. This work has provided valuable insights for the effective design of Bi-based S-scheme catalysts, which play a critical role in facilitating efficient directional transfer of photogenerated charges.