Adsorption of CO and H₂S on pristine and metal (Ni, Pd, Pt, Cu, Ag, and Au)-mediated SnS monolayers: a first-principles study

A SnS monolayer is a new two-dimensional material with a black phosphorous structure, with high carrier mobility and a large surface-to-volume ratio, and is an ideal candidate material for gas sensors. The adsorption and sensing behaviors between the SnS monolayer and gas molecules are enhanced under the action of TM atoms with high catalytic performance. The adsorption behavior of CO and H2S on intrinsic and transition metal atom modified SnS monolayers is investigated based on the first principles calculations. The adsorption structure, adsorption energy, electron transfer, density of states, electron local density, work function, and desorption properties are discussed to evaluate the potential applications of SnS monolayers as scavengers and gas sensors for CO and H2S molecules. The results show that Ni, Pd, Pt and Cu atoms tend to be adsorbed on TH sites, while Ag and Au atoms are more easily captured by TS sites. Further studies have shown that all TM atoms can significantly enhance the sensing behavior between the SnS monolayer and the gas molecules. The adsorption performance of the CO molecule on the TM-mediated SnS (TM-SnS) monolayer is obviously better than that of the H2S molecule. Furthermore, the effects of electric field and biaxial strain on the sensing properties of gas molecules on Ni-SnS monolayers are also investigated. Finally, the desorption time of gas molecules from the TM-SnS monolayer is estimated. This will provide experimenters with theoretical guidance for the application of SnS-based sensing materials, and our work is of great significance for predicting new monochalcogenide sensing materials.