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

Graphical Two morphologically structured In 2 O 3 -coated BiVO 4 photoanodes were successfully designed and fabricated. The formation of a heterojunction effectively promotes the migration and separation of interface charges, while the passivation effect effectively modulates the interfacial energy of the photoanode and induces an anodically shifted hole quasi-Fermi level and flattened band bending, both driving the high-selective generation of H 2 O 2 . 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.