AlAs/SiH van der Waals heterostructures: A promising photocatalyst for water splitting

Abstract

Here, we investigated electronic and optical properties of AlAs/SiH heterostructure by using first principle . It is demonstrated that the AlAs/SiH heterostructure is indirect type-Ⅱ bandgap heterostructure with bandgap of 2.395 eV. The work functions of monolayers and heterostructure are calculated and the interface charge transfer is theoretically analyzed. The charge density difference indicates that electrons flow from SiH monolayer to AlAs monolayer, which is consistent with theoretical results of the work functions analysis. The bandedge of AlAs/SiH heterostructure straddle the redox potential of the water in pH 0 to 14, which means that AlAs/SiH has photocatalytic activity in different water environments. Furthermore, the bandgap and absorption coefficient of heterostructure can be well adjusted by changing the interfacial strain. We also found through calculation that AlAs/SiH heterostructure has an absorption peak of 2.2 × 10 5 cm −1 in the visible region. At −2% compressive stress, AlAs/SiH heterostructure have a peak value of 2.5 × 10 5 cm −1 at 3.2 eV. At 4% tensile stress, absorption spectrum can span the whole visible region. These fascinating properties indicate that AlAs/SiH heterostructure is a highly efficient photocatalyst . • AlAs/SiH can effectively separate photogenerated carriers. • Interfacial strain can be used to tune the optical and electrical properties of heterojunction. • Excellent absorption coefficient in visible light range. • AlAs/SiH has an excellent absorption efficiency and is a promising photocatalyst.