Monolayer Sc 2 CO 2 : A Promising Candidate as a SO 2 Gas Sensor or Capturer

Toxic gaseous SO 2 adsorption on O-terminated M 2 CO 2 (M = Sc, Hf, Zr, and Ti) monolayers has been studied by means of first-principle calculations. It is demonstrated that monolayer Sc 2 CO 2 is most preferred for the SO 2 molecule with suitable adsorption strength and apparent charge transfer. Moreover, the electronic conductivity of Sc 2 CO 2 displays a sharp increase after the adsorption of SO 2 . In particular, the adsorption strength of SO 2 on Sc 2 CO 2 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 SO 2 gas. These distinctive features endow the Sc 2 CO 2 monolayer with high selectivity and sensitivity as a potential candidate for SO 2 gas sensor, as well as efficient control for gaseous SO 2 capture.