Facilitating photogenerated carrier transfer and water oxidation kinetics of BiVO4 photoanode via novel Zn@Co3C functional layer

Currently, the sluggish charge transfer kinetics and water oxidation kinetics are still the bottlenecks faced by BiVO4 photoanodes at present. Herein, an excellent Zn@Co3C functional layer is reported for the first time to tackle these problems of BiVO4 photoanode. Zn@Co3C was prepared using a facile electrochemical method with 1,2-dimethylimidazole as a carbon source. In the BiVO4/Zn@Co3C photoanode, Co3C acts as a novel oxygen evolution co-catalyst to significantly enhance water oxidation kinetics. An electron depletion layer formed around Zn species provides a strong driving force for the migration of photogenerated holes from BiVO4 to Co3C catalytic sites. Furthermore, the alternating distribution of Co3C and Zn species on the surface of BiVO4 photoanodes increases the utilization efficiency of Co3C co-catalyst. The BiVO4/Zn@Co3C system constructed in this work not only demonstrates good photoelectrochemical performance in electrolytes (4.6 mA cm−2 at 1.23 V vs. RHE without any hole scavengers), but also enables water splitting in natural seawater. This work demonstrates a novel functional layer that simultaneously facilitates photogenerated carrier transfer and water oxidation kinetics, which holds great promise for constructing high-performance water oxidation systems in various photoanodes.