Sc2CO2 and Mn-doped Sc2CO2 as gas sensor materials to NO and CO: A first-principles study

One of the most important and indispensable applications for 2D materials is toxic gas sensor. By adopting the density functional theory type of first-principles methods, we studied MXenes X2CO2 (X = Sc, Ti, Zr and Hf) as the gas sensor material to NO and CO. Our calculations show that Sc2CO2 is sensitive to NO molecule due to the chemical interaction and large charge transfer of 0.303 e between them, which will induce current change and then be detected. More importantly, the interaction is further enhanced by applying the external strain, indicating the potential of Sc2CO2 as the gas capturer material. Additionally, the adsorption of CO on Sc2CO2 is significantly improved by Mn doping, which is also detectable due to the strong adsorption energy of - 0.85 eV. Our study broadens the application of Sc2CO2 in gas sensor and provides feasible way to enhance the CO sensibility of MXene materials.