Engineering MoOx/MXene Hole Transfer Layers for Unexpected Boosting Photoelectrochemical Water Oxidation

The development of semiconductor photoanodes is of great practical interest for the realization of photoelectrochemical (PEC) water splitting. Herein, MXene quantum dots (MQD) were grafted on a BiVO4 substrate, then a MoOx layer by combining an ultrathin oxyhydroxide oxygen evolution cocatalyst (OEC) was constructed as an integrated photoanode. The OEC/MoOx/MQD/BiVO4 array not only achieves a current density of 5.85 mA cm(-2) at 1.23 V versus a reversible hydrogen electrode (vs. RHE), but also enhances photostability. From electrochemical analysis and density functional theory calculations, high PEC performance is ascribed to the incorporation of MoOx/MQD as hole transfer layers, retarding charge recombination, promoting hole transfer and accelerating water splitting kinetics. This proof-of-principle work not only demonstrates the potential utilization of hole transfer layers, but also sheds light on rational design and fabrication of integrated photoanodes for feasible solar energy conversion.

Automated summary

The research grafting MXene quantum dots onto a BiVO4 substrate and constructing an integrated photoanode achieved high current density and photostability, mainly due to the role of MoOx/MQD layers as charge transfer layers. Therefore, this study not only demonstrates the potential utilization of charge transfer layers, but also provides a new design direction for photoelectrochemical water splitting.