Toxic gaseous SO2 adsorption on O-terminated M2CO2 (M = Sc, Hf, Zr, and Ti) monolayers has been studied by means of first-principle calculations. It is demonstrated that monolayer Sc2CO2 is most preferred for the SO2 molecule with suitable adsorption strength and apparent charge transfer. Moreover, the electronic conductivity of Sc2CO2 displays a sharp increase after the adsorption of SO2. In particular, the adsorption strength of SO2 on Sc2CO2 can be further enhanced or weakened by applying tensile strains or controlling external electronic fields, which is greatly desirable to realize the capture or reversible release of toxic SO2 gas. These distinctive features endow the Sc2CO2 monolayer with high selectivity and sensitivity as a potential candidate for SO2 gas sensor, as well as efficient control for gaseous SO2 capture.

A GeS monolayer serves as an optimal NO2 gas sensor and capturer even in background water and oxygen.

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