Interfacial Catalytic Mechanism of the Oxidation Reactions of SF6 Primary Decomposition Products by Cu Surface

Operational experience shows that the thermal stability of SF6 in gas-insulated switchgear (GIS) is lower than expected. Metallic copper inside the equipment may have a significant catalytic effect on the primary decomposition and secondary reactions of SF6, while the catalytic mechanism has not been explored. To this end, the article calculated and obtained the adsorption configuration of O-2 on the Cu(111) surface based on density functional theory (DFT). A model was established for the reaction of low-fluorine sulfide with O and O-2 on the Cu surface, which initially revealed the oxidation mechanism of SF6 primary decomposition products on the Cu surface under the GIS over-thermal fault. Further, based on transition state (TS) theory and chemical kinetics analysis, the article compared the interfacial reactions' energy barriers and rate constants with the corresponding gas-phase reactions. This way, the main reaction sites of four essential oxidation reaction pathways were identified. The catalytic /inhibitory mechanism of the Cu interface on the reaction was also analyzed. This study fills the gap in the research on the surface reaction mechanism during SF6 decomposition under GIS failure.