Cu-doped P₃S-I monolayer: selective and robust toxic gas detection in ambient environments

The effects of Cu doping and the adsorption of six small molecules (NO, NO₂, NH₃, CO, SO₂, and H₂S) on the geometric structure and electronic properties of a two-dimensional P₃S-I monolayer were investigated by density functional theory (DFT). The results reveal that, compared to the intrinsic P₃S-I material with a bandgap of 1.665 eV, the bandgaps of both the doped and small molecule adsorption systems decrease. Among them, the change of bandgaps of NO, NO₂, and SO₂ adsorption systems is more significant. Furthermore, calculations of adsorption energy, Bader charge, differential charge density, density of states, and crystal orbital Hamilton population (COHP) validate that these three gas molecules have a pronounced influence on the electronic properties of P₃S-I, making them effective for detection.