A type-II GaN/InS van der Waals heterostructure with high solar-to-hydrogen efficiency of photocatalyst for water splitting

Abstract

Constructing heterostructure is a feasible way to look for powerful photocatalysts for water decomposition. Here, the monolayers GaN and InS are selected to construct the heterostructure, and the structure stability, electronic properties, Barder charge, optical performance and solar-to-hydrogen (STH) efficiency are details calculated by first-principle calculations. The results show that the GaN/InS van der Waals (vdW) heterojunction is a semiconductor with an indirect bandgap and has an inherent type-II band alignment, which can effectively separate photo-generated carriers and enhance their lifetime. The band edge positions of GaN/InS vdW heterostructure meet the requirement of photocatalyst to overall split water. Moreover, the charge density indicates that GaN monolayer is negatively charged while InS monolayer is positively charged. The interface of GaN/InS vdW heterojunction generates a built-in electric field pointing from InS to GaN, which can suppress the recombination of photogenerated electron-hole pair. Furthermore, the GaN/InS vdW heterostructure has more excellent optic performance in the visible region and fascinating STH efficiency, effectively improving solar energy utilization. These interesting properties render the GaN/InS vdW heterostructure high-efficiency photocatalysts for decomposing water. We also believe that the investigation of such vdW heterostructures has a significant meaning for the prediction and improvement of photocatalyst efficiency, as well as provides effective guidance for future applications of photoelectronic devices.