Novel two-dimensional Ga(In)S1-xSex as high-efficiency OER catalysts for photocatalytic water splitting

The suitable band gap, abundant absorption utilization in sunlight, excellent carrier separation for efficient surface activity and sufficient driving force for redox reaction are fundamental to a promising water splitting photocatalyst. Here, the photocatalytic properties of Ga(In)S1-xSex (0 <= x <= 1) monolayers are investigated systematically by DFT calculations since they are proposed as photocatalysts of highly efficient and spontaneous water splitting. The results reveal that Ga(In)S1-xSex monolayers possesses widely band gaps from 2.41 eV to 3.35 eV, and the band alignment exhibits suitable band positions for redox reaction of water splitting. Meanwhile, the free energies of reaction on these monolayers are all downhill indicating that OER of water splitting is a thermodynamically favored reaction. Thus, Ga(In)S1-xSex monolayers exhibit excellent photocatalytic efficiency and are excellent candidates for photocatalyst. Especially, Janus Ga(In)S1-xSex (x = 0.5) could effectively separate electrons and holes, due to the internal electric field formed by the asymmetric structure. The findings open up a new avenue for designing novel 2D OER catalysts for photocatalytic water splitting.