Trimetallic oxyhydroxide modified 3D coral-like BiVO4 photoanode for efficient solar water splitting

Abstract

Water splitting driven by sunlight is considered to be a promising strategy for solving energy crisis and environment pollution. But the sluggish kinetics of oxygen evolution reaction (OER) is quite limited for improving the efficiency of solar conversion. In this study, a core-shell nanostructure film of WCoFe oxyhydroxide coated BiVO4 (WCoFe/BiVO4) was constructed by solvothermal method, which exhibits better photoelectrochemical (PEC) properties compared with the bare BiVO4. A high quality-interface is formed between WCoFe oxyhydroxide and BiVO4 junctions, which further facilitates the separation and transport of photogenerated carriers. Notably, WCoFe/BiVO4 photoanode shows a low onset potential of 0.28 V vs. reversible hydrogen electrode (RHE) and a significant enhancement of photocurrent density, reaching 4.35 mA cm−2 at 1.23 VRHE, which is mainly attributed to the improved OER kinetics. In addition, the charge injection efficiency of WCoFe/BiVO4 photoanode also increases to 84.75%, more than twice as much as that of bare BiVO4 photoanode. Photoelectrochemical measurements and optical studies have demonstrated that the high PEC performance can be contributed to the reduced OER barriers and charge recombination, as well as the excellent optical transparency of WCoFe oxyhydroxide.