Cobalt-Doped Magnetite Overlayer on Mo-Doped BiVO₄ Photoanode for Efficient Photoelectrochemical Water Oxidation

BiVO4 has garnered considerable interest as a viable photoanode material for photoelectrochemical (PEC) water oxidation owing to its favorable bandgap and suitable band edge position. However, the PEC oxygen evolution property of pristine BiVO4 seriously suffers from its poor surface kinetics and rapid charge recombination. In this study, we demonstrate a combination of element doping and a heterostructure construction strategy, where a Co-doped Fe3O4 (Co:Fe3O4) layer is decorated on the surface of Mo doped BiVO4 (BVO), which results in optimized charge transfer efficiency, charge transport efficiency, and boosted surface PEC oxygen evolution reaction (OER) active sites of the Co:Fe3O4/BVO photoanode. Consequently, the Co:Fe3O4/BVO achieves a 1.9-fold better PEC water oxidation performance at 1.23 VRHE under 1 sun illumination, compared to BVO. Furthermore, the PEC two-electrode system constructed by Co:Fe3O4/BVO and Pt wire shows a high O2 evolution rate of 28.83 μmol cm–2 h–1 with a high Faradaic efficiency over 85%.