A Reusable and High Sensitivity Nitrogen Dioxide Sensor Based on Monolayer SnSe

The sensing properties of monolayer tin selenium (SnSe) for CO, CO2, NH3, H2O, and NO2 gas molecules are theoretically investigated by the first-principle calculation based on density functional theory. The adsorption energy, equilibrium distance, and Mulliken charge transfer are calculated to evaluate the adsorption properties of the SnSe monolayer for these gas molecules. All the molecules show physisorption nature on the SnSe monolayer. The results demonstrate that SnSe is sensitive to NO2 gas molecules with moderate adsorption energy and superior charge transfer. Furthermore, only the adsorption of NO2 can modify the densities of states of SnSe near the Fermi level. The current-voltage (I-V) curves reveal that the conductivity of the SnSe monolayer is distinctly increased after NO2 adsorption. The recovery time of the SnSe sensor at T = 300 K is estimated to be quite short for NO2, which satisfies the demand of sustainable use. Therefore, our results can provide a theoretical basis for the potential applications of monolayer SnSe in NO2 detecting at room temperature.