Cobalt-Doped\nMagnetite Overlayer on Mo-Doped BiVO<sub>4</sub> Photoanode for Efficient\nPhotoelectrochemical Water Oxidation

BiVO<sub>4</sub> has garnered considerable interest as\na viable\nphotoanode material for photoelectrochemical (PEC) water oxidation\nowing to its favorable bandgap and suitable band edge position. However,\nthe PEC oxygen evolution property of pristine BiVO<sub>4</sub> seriously\nsuffers from its poor surface kinetics and rapid charge recombination.\nIn this study, we demonstrate a combination of element doping and\na heterostructure construction strategy, where a Co-doped Fe<sub>3</sub>O<sub>4</sub> (Co:Fe<sub>3</sub>O<sub>4</sub>) layer is decorated\non the surface of Mo doped BiVO<sub>4</sub> (BVO), which results in\noptimized charge transfer efficiency, charge transport efficiency,\nand boosted surface PEC oxygen evolution reaction (OER) active sites\nof the Co:Fe<sub>3</sub>O<sub>4</sub>/BVO photoanode. Consequently,\nthe Co:Fe<sub>3</sub>O<sub>4</sub>/BVO achieves a 1.9-fold better\nPEC water oxidation performance at 1.23 V<sub>RHE</sub> under 1 sun\nillumination, compared to BVO. Furthermore, the PEC two-electrode\nsystem constructed by Co:Fe<sub>3</sub>O<sub>4</sub>/BVO and Pt wire\nshows a high O<sub>2</sub> evolution rate of 28.83 μmol cm<sup>–2</sup> h<sup>–1</sup> with a high Faradaic efficiency\nover 85%.