Simultaneous enhancement of charge transfer and surface catalysis through a polymetallic oxide cocatalyst on BiVO4 photoanodes for highly efficient and stable water oxidation

The rate-determining oxygen evolution reaction (OER) always limits the high-efficient conversion of solar energy to green hydrogen fuels through photoelectrocatalytic or photocatalytic water splitting. The high catalytic overpotential and the instability of catalytic center are commonly regarded as the primary factors contributing to the low rate of OER, remaining to be a challenge in the field of water splitting. Herein, a polymetallic oxide cocatalyst (Mo-MnO y /FeCoNiO x ) with well-defined electronic and catalytic properties is designed on BiVO 4 photoelectrode for highly efficient and stable photoelectrocatalytic water oxidation. The experimental characterization demonstrates that the dual-layer design of Mo-MnO y /FeCoNiO x can significantly optimizes the electronic property of MnO y and FeCoNiO x components, boosting the photogenerated charge transfer between Mo-MnO y /FeCoNiO x cocatalyst and BiVO 4 photoelectrode. The density functional theory (DFT) simulation reveals that the Mo sites in Mo-MnO y layer can activate the neighboring surface Mn sites instead of directly serving as the catalytic center, thereby establishing these Mn sites as primary active centers for achieving stable OER. The developed Mo-MnO y /FeCoNiO x /BiVO 4 photoelectrode exhibits a current density of 6.18 mA cm −2 with an excellent stability for 30 h at 1.23 V RHE under 1 sun irradiation, exhibiting the excellent activity and durability. This work sheds light on design of high-performance multiple-component water-oxidation cocatalyst on photoanode.