Indium Oxide Layer Dual Functional Modified Bismuth Vanadate Photoanode Promotes Photoelectrochemical Oxidation of Water to Hydrogen Peroxide.

The photoelectrochemical (PEC) dual-electron pathway for water oxidation to produce hydrogen peroxide (HO) shows promising prospects. However, the dominance of the four-electron pathway leading to O evolution competes with this reaction, severely limiting the efficiency of HO production. Here, we report a InO passivator-coated BiVO (BVO) photoanode, which effectively enhances the selectivity and yield of HO production via PEC water oxidation. Based on XPS spectra and DFT calculations, a heterojunction is formed between InO and BVO, promoting the effective separation of interface and surface charges. More importantly, Mott-Schottky analysis and open-circuit potential measurements demonstrate that the InO passivation layer on the BVO photoanode shifts the hole quasi-Fermi level towards the anodic direction, enhancing the oxidation level of holes. Additionally, the widening of the depletion layer and the flattening of the band bending on the InO-coated BVO photoanode favor the generation of HO while suppressing the competitive O evolution reaction. In addition, the coating of InO can also inhibit the decomposition of HO and improve the stability of the photoanode. This work provides new perspectives on regulating PEC two/four-electron transfer for selective HO production via water oxidation.