Nitrogen Dioxide Gas Sensor Based on Monolayer SnS: A First-Principle Study

The sensing behavior of monolayer tin sulfide (SnS) for four gas molecules (NH ₃ , NO ₂ , CO, and H ₂ O) are studied by the first-principle calculation based on density-functional theory. We calculate adsorption energy, adsorption distance, and Hirshfeld charge to estimate the adsorption ability of monolayer SnS for these gas molecules. The results demonstrate that all the gas molecules show physisorption nature. We further calculate the current-voltage (I-V) curves using the nonequilibrium Green's function formalism for evaluating the NO ₂ gas sensing properties. The monolayer SnS is found to be strongly sensitive to NO ₂ molecule dependent on moderate adsorption energy, excellent charge transfer, and significant change of I-V property before and after gas adsorption. Therefore, we suggest that monolayer SnS can be a prominent candidate for application as NO ₂ gas sensor.