STRAIN EFFECTS ON ENHANCED HYDROGEN SULPHIDE DETECTION CAPABILITY OF Ag-DECORATED DEFECTIVE GRAPHENE: A FIRST-PRINCIPLES INVESTIGATION

Strain effects on hydrogen sulphide (H2S) adsorption on Ag-decorated Stone-Wales (SW) defect in graphene were investigated by density functional theory calculations. The results indicate that an Ag adatom is easily pinned chemically on the top of the most stretched C-C bond at the SW defect in graphene without mechanical strains. A modest uniform tensile strain (8%) applied in defective graphene greatly increases the binding energy of Ag by 44%, indicating the strain enhanced stabilization of Ag on SW defect. Using the resulting Ag-decorated defective graphene (Ag-SW-g) composite as a model for H2S molecule detection, we found that the tensile strain has little effects on the interaction between the molecule and the composite, and the adsorption energies of H2S around 1.6 eV which is six times larger than that on pristine graphene are produced. The enhanced H2S adsorption on Ag-SW-g is attributed to charge transfer from the molecule to the graphene through the bridge-like Ag adatom. In addition, the electronic property of the Ag-SW-g under different strains changes from a metallic state to a semiconductor state upon H2S adsorption, which should lead to an observable change in its conductivity. These findings pave the way for future development of graphene-based gas sensor.