The adsorption and sensing mechanism of toxic gases HCN, NO2, NH3 and Cl2 on Mo, Ag-modified WSe2 monolayer: Insights from the first-principles computations

In accordance to the density functional theory, the adsorption properties of toxic gases (HCN, Cl-2, NH3, and NO2) upon pristine and X-doped (X = Mo, Ag) two-dimensional (2D) WSe2 were explored in this work. The adsorption performances were simulated and analyzed in terms of the charge transfer, DOS and molecular orbital. Results show that both Ag-WSe2 and Mo-WSe2 exhibit satisfactory adsorption capacity for HCN, Cl-2, NH3, and NO2. Occurrence of chemisorption for the four gases on Mo-WSe2 monolayer is indicated by the exceptional molecular deformation, significant charge transfer and adsorption energy. Ag-WSe2 and Mo-WSe2 monolayer might be favorable materials for the sensing industrial toxic gases. In addition, Mo-doped WSe2 monolayer performs better in adsorbing NH3, NO2 and HCN than Ag-doped WSe2 monolayer, while Ag-doped WSe2 monolayer exhibits more satisfactory adsorption properties on Cl-2. Finally, the NO2 molecule can be adsorbed better on both AgWSe2 monolayer and Mo-WSe2 monolayer, compared with NH3, Cl-2 and HCN. This paper manifests that X-doped (X = Mo, Ag) WSe2 may be recommended in the field of toxic gases detection.