The Al2XS4 (X = Cd, Zn and Hg) for promising photocatalytic performance: First-principles investigations

[Display omitted] •We are convinced that Al2CdS4, Al2ZnS4 and Al2HgS4 is a promising visible light photocatalyst. The reasons can be summarized as follows: These materials has a suitable band gap value (2.525 eV – 2.661 eV) and has a visible light range.•These conclusions clearly indicate that the photogenerated electrons and holes in the Al2HgS4 are spatially separated, which can effectively reduce the carrier recombination rate. H2 is one of the lightest gases, non-toxic, odourless, with a combustion product of water and a calorific value 2.8 times that of gasoline, and is therefore considered to be one of the most desirable sources of clean energy. The electronic structure and optical properties of three structures of intrinsic Al2XS4 (X = Cd, Zn and Hg) have been investigated using the GGA-PBE method. The calculated valence-conduction band positions indicate that all three structures satisfy the conditions for hydrogen production by hydrolysis.The high absorption coefficient of Al2HgS4 in the visible region implies that Al2HgS4 can efficiently utilise solar energy, suggesting that this structure is a potential visible light responsive semiconductor photocatalyst.