DFT investigation on highly selective NO2 sensing properties of MnPS3

Among transition metal thiophosphates (MPX3), p-type semiconductor MnPS3 is considered to be a promising sensor material due to high selectivity and sensitivity to NO2. To explore gas sensing mechanism of MnPS3 at atomic scale, the electronic properties of NO2, NH3, H2, CO, CO2, C2H2, H2S and CH4 gases in MnPS3 monolayer are analyzed by density functional theory. The calculated charge transfer, adsorption energy, density of state and band gap change suggest that MnPS3 exhibits an intense sensing performance to NO2 than other gases. Upon the adsorption of NO2, one of the NO bond in NO2 breaks and a PO bond forms between NO2 and MnPS3. Further, a significant increasing on DOS occurs near Fermi level, suggesting an obvious change in electric conductivity of MnPS3. The energy barrier and diffusion coefficient shows that the gases are easier to diffuse between adjacent vacancies on the surface of MnPS3, and NO2 is relatively difficult to diffuse than other gases due to chemical adsorption. This work provides a theoretical basis for designing MnPS3-based NO2 sensor.