Environmental Gas Adsorption on SnGe₂N₄: A Theoretical Perspective

Based on spin-polarized density functional theory (DFT) calculations, a systematic study was conducted on the adsorption behavior of gas molecules such as H₂, CO, CO₂, H₂O, NO₂, H₂S, NH₃, and CH₄ on the SnGe₂N₄ monolayer surface. The results indicate that all gas molecules exhibit relatively low adsorption energies and large adsorption distances on the SnGe₂N₄ surface, suggesting a tendency toward physisorption. Charge density difference (CDD) and Bader charge analysis demonstrate minimal charge transfer, confirming weak interactions between the gas molecules and the SnGe₂N₄ surface. Analyzing the band structures and density of states of SnGe₂N₄ monolayers adsorbed with different gas molecules reveals that except for NO₂ and H₂S, the adsorption of other gas molecules does not significantly affect the electronic properties of the SnGe₂N₄ surface. Notably, NO₂ adsorption induces spin polarization, potentially influencing the sensing mechanism. Notably, the adsorption energy of NO₂ on the SnGe₂N₄ surface (-1.08 eV) is significantly higher than that of other gas molecules, and NO₂ exhibits the most significant charge transfer (-0.051 e) with the SnGe₂N₄ surface. Our findings provide fundamental insights into the gas adsorption properties of SnGe₂N₄, which could be beneficial for its application in gas sensing technologies.