Optoelectronic and photocatalytic behaviour of a type-II GaAlS₂/HfS₂heterostructure:ab initiostudy

Theoretical examination based on first principle computation has been conducted for van der Waals heterostructure (vdwHS) GaAlS₂/HfS₂including structural, optoelectronic and photocatalytic characteristics. From the adhesion energy calculation, the AB configuration of GaAlS₂/HfS₂vdwHS is the most stable. A type-II GaAlS₂/HfS₂vdwHS is a dynamically and thermally stable structure. The band edge position, projected band, and projected charge densities verify the type-II alignment of GaAlS₂/HfS₂vdwHS. For GaAlS₂/HfS₂, GaAlS₂is acting as a donor and HfS₂is acting as an acceptor ensured by the charge density difference plot. The electron localized function validates the weak van der Waals interaction between GaAlS₂and HfS₂. The GaAlS₂/HfS₂vdwHS possess an indirect bandgap of 1.54 eV with notable absorption in the visible range. The findings assure that the GaAlS₂/HfS₂vdwHS is an efficient photocatalyst for pH 4-8. The band alignment of GaAlS₂/HfS₂is suitable for Z-scheme charge transfer. The strain influenced band edge suggests that the GaAlS₂/HfS₂vdwHS remains photocatalytic for strain-4%to+6%in both cases of uniaxial and biaxial strains.