Abstract
Detection of decomposition products of sulfur hexafluoride (SF6) 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 SF6, including SO2F2, SOF2, and SO2, based on density functional theory (DFT). We thoroughly investigated a series of parameters presenting gas-sensing properties of adsorbing process about gas molecule (SO2F2, SOF2, SO2) and double gas molecules (2SO2F2, 2SOF2, 2SO2) 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. SO2F2 and SO2 gas molecules on Ag-graphene presented chemisorption, and the adsorption strength was SO2F2 > SO2, while SOF2 absorption on Ag-graphene was physical adsorption. Thus, we concluded that Ag-graphene showed good selectivity and high sensitivity to SO2F2. The results can provide a helpful guide in exploring Ag-graphene material in experiments for monitoring the insulation status of SF6-insulated equipment based on detecting decomposition products of SF6.
Highlights
Sulfur hexafluoride (SF6 ) has been widely applied in gas-insulated switchgears (GIS) because of its excellent insulation and arc-quenching performance [1]
When the insulation performance of electrical equipment begins to decline, the energy released by the partial discharge phenomena will cause SF6 to decompose into multiple low fluorine sulfides [2]
These results reveal that only one of the double SO2 F2 gas molecules interacted with Ag-graphene
Summary
Sulfur hexafluoride (SF6 ) has been widely applied in gas-insulated switchgears (GIS) because of its excellent insulation and arc-quenching performance [1]. When the insulation performance of electrical equipment begins to decline, the energy released by the partial discharge phenomena will cause SF6 to decompose into multiple low fluorine sulfides [2]. These low fluorine sulfides react with trace water and oxygen to generate SO2 F2 , SOF2 , SO2 , and other characteristic gas products in GIS [3]. The theory suggested that decorated Ag could effectively improve the electron density and charge transfer characteristics of graphene, which provided a new way of preparing sensing materials for functionalized graphene gas and developing a high-performance gas sensor for detection of SF6 decomposition products
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