A new bifunctional C3N nanosheet of NO2, SO2 gas sensor and CO2 separation: A first-principles study

A new-style two-dimensional C3N monolayer, unlike the honeycomb C3N monolayer, is proposed as a gas sensor, capture and separation. By using the first-principles method, the adsorption behaviors of gas molecules (NH3, H2S, SO2, CO, CO2, NO, NO2, CH4, HCN, N-2, H-2 and O-2) on the C3N monolayer were investigated, and the charge density difference, density of state and Hirshfeld charge of those adsorption systems were also discussed. The results show that the SO2 and NO2 are chemisorbed on the C3N nanosheet with large adsorption strength, while the other gases are adsorbed by weak physisorption. The analysis of charge density difference and density of state suggests that SO2 and NO2 gain much charge from C3N sheet, and the hybridizations between C3N sheet and SO2/NO2-p orbitals lead to strong gas-adsorbent interactions. The recovery time of SO2 and NO2 is predicted to be 7.47 x 10(-4) s and 15.91 s at room temperature. Additionally, the CO2 can be captured and separated from the mixtures of CO2, NH3, H2S, CO, CH4, H-2 through injecting two electrons into C3N sheet. Therefore, the new C3N nanosheet can be a promising bifunctional material as SO2, NO2 sensor and CO2 separation.