Design of high-efficiency visible-light photocatalysts for water splitting: MoS₂/AlN(GaN) heterostructures

Hydrogen fuel produced from water splitting using solar energy and a catalyst is a clean and renewable future energy source. Great efforts in searching for photocatalysts that are highly efficient, inexpensive, and capable of harvesting sunlight have been made for the last decade, which, however, have not yet been achieved in a single material system so far. Here, we predict that MoS₂/AlN(GaN) van der Waals (vdW) heterostructures are sufficiently efficient photocatalysts for water splitting under visible-light irradiation based on ab initio calculations. Contrary to other investigated photocatalysts, MoS₂/AlN(GaN) vdW heterostructures can separately produce hydrogen and oxygen at the opposite surfaces, where the photoexcited electrons transfer from AlN(GaN) to MoS₂ during the photocatalysis process. Meanwhile, these vdW heterostructures exhibit significantly improved photocatalytic properties under visible-light irradiation by the calculated optical absorption spectra. Our findings pave a new way to facilitate the design of photocatalysts for water splitting.