Decoration of novel molybdenum-based bimetallic oxide on bismuth vanadate as photoelectrochemical catalysts for efficient water oxidation

Bismuth vanadate (BVO) with favorable band edges is regarded as an effective photocatalyst for oxygen evolution reaction (OER), which is a crucial rate-determining step in the water splitting process. Incorporating co-catalysts can lower activation energy, create hole sinks, and enhance the photocatalytic capabilities of BVO. Bimetallic oxide is reported to have suitable band positions and catalytic activities toward OER. In this study, molybdenum-based bimetallic oxides are introduced as the co-catalyst for BVO to improve their photocatalytic properties toward OER. Molybdenum-based bimetallic oxides coupled with Zn, Ni, Cu, Co and Mn are coated on BVO by a drop-casting technique to achieve uniform coverage of the co-catalyst/photocatalyst systems. The BVO coated by Mo-based bimetallic oxide with Ni (NiMo/BVO) shows the highest photocurrent density of 3.92 mA/cm² at 1.23 V versus reversible hydrogen electrode and the largest applied bias photon-to-current efficiency (ABPE) of 1.24%. The BVO photoanode only shows a photocurrent density of 0.52 mA/cm² and an ABPE value of 0.09%. The NiMo/BVO photoanode also achieves excellent long-term stability with the photocurrent retention of 95% after continuous illumination for 7500 s. The innovation of this work is firstly to design efficient Mo-based co-catalysts to improve the photocatalytic ability of BVO toward water oxidation.