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 NO 2 , SO 2 , and NO on SnS have been thoroughly investigated. The results indicate that SnS can effectively adsorb NO 2 , SO 2 , and NO gases, attributed to their higher adsorption energies. Differing from the case of SO 2 adsorption, SnS undergoes a transition from a non-magnetic state to a magnetic state upon the adsorption of NO 2 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 NO 2 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 NO 2 gas sensor.