DFT Study of Zn-Modified SnP: A HS Gas Sensor with Superior Sensitivity, Selectivity, and Fast Recovery Time.

The adsorption properties of Cu, Ag, Zn, and Cd-modified SnP monolayers for HS have been studied using density functional theory (DFT). Based on phonon spectrum calculations, a structurally stable intrinsic SnP monolayer was obtained, based on which four metal-modified SnP monolayers were constructed, and the band gaps of the modified SnP monolayers were significantly reduced. The adsorption capacity of Cu, Zn-modified SnP was better than that of Ag, Cd-modified SnP. The adsorption energies of Cu-modified SnP and Zn-modified SnP for HS were -0.749 eV and -0.639 eV, respectively. In addition, Cu-modified SnP exhibited chemisorption for HS, while Zn-modified SnP exhibited strong physisorption, indicating that it can be used as a sensor substrate. Co-adsorption studies showed that ambient gases such as N, O, and HO had little effect on HS. The band gap change rate of Zn-modified SnP after adsorption of HS was as high as -28.52%. Recovery time studies based on Zn-modified SnP showed that the desorption time of HS was 0.064 s at 298 K. Therefore, Zn-modified SnP can be used as a promising sensor substrate for HS due to its good selectivity, sensitivity, and fast recovery time.