First-Principles Study of SnS for Small Gas-Sensing Applications

Two-dimensional SnS holds significant potential in gas-sensing because of its numerous excellent characteristics. Based on first-principles density functional theory (DFT), the adsorption properties of small gas molecules such as NO2, SO2, and NO on SnS have been thoroughly investigated. The results indicate that SnS can effectively adsorb NO2, SO2, and NO gases, attributed to their higher adsorption energies. Differing from the case of SO2 adsorption, SnS undergoes a transition from a non-magnetic state to a magnetic state upon the adsorption of NO2 and NO gases. To investigate the sensing characteristics of these three adsorption systems, the adsorption densities and I–V curves were calculated using a thermodynamic statistical model and the nonequilibrium Green’s function method, respectively. These findings demonstrate that NO2 adsorption not only exhibits the highest adsorption densities but also generates the maximum current at the same voltage. These results highlight the potential of SnS for serving as a selective and reversible NO2 gas sensor.