Cu₂S/BiVO₄ Heterostructure Photoanode with Extended Wavelength Range for Efficient Water Splitting

Chalcogenides are a promising class of light-absorbers as photoanodes for photoelectrochemical water splitting. However, the oxidation and the sluggish reaction kinetics at the surface during water oxidation limit their applications in solar-driven water splitting. Here, we demonstrate an intriguing photoanode consisting of three components by deposition of Cu₂S via a simple successive ionic layer adsorption and reaction method on the surface of BiVO₄ to form a well-defined heterojunction. To protect Cu₂S from oxidation and accelerate the reaction kinetics, a thin layer of CoFe–OH has been successfully integrated uniformly on the surface. The resulting Cu₂S/BiVO₄ composite photoanode shows a wider light absorption range beyond 500 nm than bare BiVO₄ due to the incorporation of Cu₂S. The resulting photoanode exhibits dramatically enhanced performance and stability for water splitting, and the photocurrent increases to 3.07 mA/cm² at 1.23 V_RHE. This work endows chalcogenides with a promise as candidate catalysts for highly efficient and stable solar-driven reactions.