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.