Mechanistic Insights into Thermal Degradation of High-Concentration SF₆ over TiO₂-SiC Heterojunction

Sulfur hexafluoride (SF₆) is the most potent greenhouse gas known, with a global warming potential 24,300 times that of CO₂ and an atmospheric lifetime exceeding 3200 years. Its widespread industrial use necessitates effective abatement technologies, yet conventional thermal degradation requires extreme temperatures (>1000 °C). Herein, we report the efficient thermal degradation of high-concentration SF₆ over a TiO₂-SiC composite. Density functional theory (DFT) calculations first identified TiO₂ as a promising active component based on the favorable SF₆ adsorption energy. A series of TiO₂-SiC composites with varying TiO₂ loadings and particle sizes were synthesized via mechanical grinding and thoroughly characterized by TEM, XPS, and in situ XRD, revealing intimate heterojunction formation and electronic interaction between TiO₂ and SiC. Performance evaluation demonstrated that TiO₂-SiC achieves complete degradation of 70 vol % SF₆ at 600 °C, significantly outperforming TiO₂-SiO₂ and TiO₂-CeO₂ composites. Postreaction characterization by XPS, TEM-EDX, and in situ FTIR identified SO₂ and HF as primary products and elucidated the degradation mechanism. This work is based on the experimental results where TiO₂-SiC is considered a promising material for high-concentration SF₆.