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

Abstract

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 VRHE. This work endows chalcogenides with a promise as candidate catalysts for highly efficient and stable solar-driven reactions.