Sn-Cd modified Ti₂CO₂ MXene for enhanced harmful gas adsorption: A DFT study

In this study, we investigate the adsorption characteristics of the Ti₂CO₂ monolayer using density functional theory for harmful gases (NH₃, H₂S, CH₄, NO₂, SO₂). The optimal adsorption structures of the Ti₂CO₂ monolayer for different gases are determined, and the adsorption mechanisms are analyzed. NH₃ exhibits the highest absolute adsorption energy (0.429 eV) among the gases (NH₃, H₂S, CH₄, NO₂, SO₂) when physisorbed on the Ti₂CO₂ monolayer. Substitutional doping of the Ti₂CO₂ monolayer with the metal element Sn and the transition metal element Cd results in alterations to the material's electronic properties. The adsorption capacities for NH₃, H₂S, CH₄, NO₂, and SO₂ are significantly enhanced, making the Ti₂CO₂ monolayer a promising candidate for the adsorption of toxic and hazardous gases. Notably, the doping process significantly improves the adsorption performance of Ti₂CO₂ monolayer for NO₂, with the adsorption energy increasing by a factor of 10.35 compared to the original material. This substantial enhancement provides a new approach for doping modifications of Ti₂CO₂ monolayers to facilitate the adsorption of various gases.