A DFT study of PtS ₂ /GaS heterostructure for hydrogen and oxygen evolution reactions

The van der Waals heterostructure (vdW-HS) PtS 2 /GaS has been theoretically analyzed for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The configuration of vdW-HS PtS 2 /GaS with the highest stability has been identified based on ab-initio molecular dynamics, adhesion energy and phonon calculations. The investigation of electronic properties suggests that it has an indirect staggered-type bandgap of 2.36[Formula: see text]eV. The van der Waals nature of vdW-HS PtS 2 /GaS has been confirmed by the ELF calculation. Furthermore, the calculations of work function, charge density difference and planar-averaged charge density difference verify the charge transfer from monolayer GaS to monolayer PtS 2 . From the optical properties, it has been found that vdW-HS PtS 2 /GaS begins the absorption from visible range, however, exhibits enhanced absorption within the ultraviolet range of the electromagnetic spectrum. The vdW-HS PtS 2 /GaS exhibits suitable band alignment for hydrogen and oxygen evolution reactions. Moreover, HER and OER have been verified by the Gibbs energy and overpotential calculations. From the obtained results, it has been concluded that vdW-HS PtS 2 /GaS is more suitable for OER instead of oxygen reduction reaction.