Gas Sensing Analysis of Ag-Decorated Graphene for Sulfur Hexafluoride Decomposition Products Based on the Density Functional Theory

Detection of decomposition products of sulfur hexafluoride (SF(6)) is one of the best ways to diagnose early latent insulation faults in gas-insulated equipment, and the occurrence of sudden accidents can be avoided effectively by finding early latent faults. Recently, functionalized graphene, a kind of gas sensing material, has been reported to show good application prospects in the gas sensor field. Therefore, calculations were performed to analyze the gas sensing properties of intrinsic graphene (Int-graphene) and functionalized graphene-based material, Ag-decorated graphene (Ag-graphene), for decomposition products of SF(6), including SO(2)F(2), SOF(2), and SO(2), based on density functional theory (DFT). We thoroughly investigated a series of parameters presenting gas-sensing properties of adsorbing process about gas molecule (SO(2)F(2), SOF(2), SO(2)) and double gas molecules (2SO(2)F(2), 2SOF(2), 2SO(2)) on Ag-graphene, including adsorption energy, net charge transfer, electronic state density, and the highest and lowest unoccupied molecular orbital. The results showed that the Ag atom significantly enhances the electrochemical reactivity of graphene, reflected in the change of conductivity during the adsorption process. SO(2)F(2) and SO(2) gas molecules on Ag-graphene presented chemisorption, and the adsorption strength was SO(2)F(2) > SO(2), while SOF(2) absorption on Ag-graphene was physical adsorption. Thus, we concluded that Ag-graphene showed good selectivity and high sensitivity to SO(2)F(2). The results can provide a helpful guide in exploring Ag-graphene material in experiments for monitoring the insulation status of SF(6)-insulated equipment based on detecting decomposition products of SF(6).