Degradation of SF6 by dielectric barrier discharge cooperating with TiO2 photocatalysis: Insights into the reaction mechanism

Abstract

Research into the degradation and conversion of SF6 is important for environmental protection. Dielectric barrier discharge (DBD) technology is recognized as a reliable method for processing industrial waste gases, such as SF6. This research introduces a dual approach, combining DBD with TiO2 photocatalysis, to enhance SF6 degradation. When operating at 90 W, the degradation removal efficiency (DRE) of 2 % SF6 reaches 99.99 %. Moreover, the energy efficiency, measured as G50, reaches 10.25 g/(kW·h) for the combined DBD and TiO2 photocatalysis system, is, surpassing the efficiency of the standalone DBD system. The introduction of 0.5 % H2O enables complete SF6 degradation at a reduced input power (70 W). This synergy promotes the generation of a more easily processed product, SO2. Density functional theory (DFT) studies indicate that the availability of active sites on TiO2(101) is a crucial factor affecting the degradation efficiency. Specifically, the pre-adsorption of H2O on TiO2(101) surfaces facilitates the initial bond dissociation of SF6, while these surfaces strongly adsorb crucial intermediates, thereby enhancing the degradation of SF6. Additionally, the selectivity of the products was related to the dissociation energy barriers, and the pre-adsorption of H2O reduces these barriers for key intermediates, thereby improving SO2 selectivity. This study provides new insights into SF6 degradation and conversion using DBD combined with photocatalysis and provides inspiration for the conversion of other greenhouse gases (CO2, CH4, etc.).