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

BiVO 4 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 BiVO 4 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 Fe 3 O 4 (Co:Fe 3 O 4 ) layer is decorated on the surface of Mo doped BiVO 4 (BVO), which results in optimized charge transfer efficiency, charge transport efficiency, and boosted surface PEC oxygen evolution reaction (OER) active sites of the Co:Fe 3 O 4 /BVO photoanode. Consequently, the Co:Fe 3 O 4 /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:Fe 3 O 4 /BVO and Pt wire shows a high O 2 evolution rate of 28.83 μmol cm –2 h –1 with a high Faradaic efficiency over 85%.