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

Abstract The photoelectrochemical (PEC) dual‐electron pathway for water oxidation to produce hydrogen peroxide (H 2 O 2 ) shows promising prospects. However, the dominance of the four‐electron pathway leading to O 2 evolution competes with this reaction, severely limiting the efficiency of H 2 O 2 production. Here, we report a In 2 O 3 passivator‐coated BiVO 4 (BVO) photoanode, which effectively enhances the selectivity and yield of H 2 O 2 production via PEC water oxidation. Based on XPS spectra and DFT calculations, a heterojunction is formed between In 2 O 3 and BVO, promoting the effective separation of interface and surface charges. More importantly, Mott‐Schottky analysis and open‐circuit potential measurements demonstrate that the In 2 O 3 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 In 2 O 3 ‐coated BVO photoanode favor the generation of H 2 O 2 while suppressing the competitive O 2 evolution reaction. In addition, the coating of In 2 O 3 can also inhibit the decomposition of H 2 O 2 and improve the stability of the photoanode. This work provides new perspectives on regulating PEC two/four‐electron transfer for selective H 2 O 2 production via water oxidation.