Optoelectronic and photocatalytic behaviour of a type-II GaAlS₂/HfS₂ heterostructure: ab initio study

Theoretical examination based on first principle computation has been conducted for van der Waals heterostructure (vdwHS) GaAlS 2 /HfS 2 including structural, optoelectronic and photocatalytic characteristics. From the adhesion energy calculation, the AB configuration of GaAlS 2 /HfS 2 vdwHS is the most stable. A type-II GaAlS 2 /HfS 2 vdwHS is a dynamically and thermally stable structure. The band edge position, projected band, and projected charge densities verify the type-II alignment of GaAlS 2 /HfS 2 vdwHS. For GaAlS 2 /HfS 2 , GaAlS 2 is acting as a donor and HfS 2 is acting as an acceptor ensured by the charge density difference plot. The electron localized function validates the weak van der Waals interaction between GaAlS 2 and HfS 2 . The GaAlS 2 /HfS 2 vdwHS possess an indirect bandgap of 1.54 eV with notable absorption in the visible range. The findings assure that the GaAlS 2 /HfS 2 vdwHS is an efficient photocatalyst for pH 4–8. The band alignment of GaAlS 2 /HfS 2 is suitable for Z-scheme charge transfer. The strain influenced band edge suggests that the GaAlS 2 /HfS 2 vdwHS remains photocatalytic for strain − 4 % to + 6 % in both cases of uniaxial and biaxial strains.