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 V_RHE 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%.