SnSe monolayer: A promising candidate of SO2 sensor with high adsorption quantity

Recently, the application of phosphorene structure analogues in gas sensors has been a hot research topic since the appearance of phosphorene. SnSe monolayer as one of them has been proved to be much more stable properties than phosphorene. Based on the density-functional theory, the interaction between gas molecules (CO, CO2, O2, NO, NH3, SO2 and NO2) and SnSe monolayer are theoretically investigated by first-principles calculation. Macroscopically, gas molecules selective adsorption of SnSe monolayer is analyzed by molecular dynamics. Compared to CO, CO2, O2, SnSe monolayer performs stronger affinity for SO2 and NO2, which possesses appropriate adsorption energies (−6.000 eV and −0.759 eV) and elevated charge transfers (−0.239 e and −0.328 e). SnSe monolayer chemical adsorption of NO2, while physically adsorbing SO2, is more suitable for the adsorption mode of SO2 sensors. Surprisingly, the adsorption amount of SO2 is 6 times that of NO2. Therefore, the adsorption of SO2 is more likely to occur compared to other gas molecules. For a mixed environment of SO2 and NO2, the adsorption quantity of SO2 is not significantly affected, while the adsorption of NO2 is inhibited. Therefore, the SnSe monolayer could be a promising candidate as SO2 sensors with high selectivity and sensitivity.