Theoretical study of the interaction of SF6 molecule on Ti3C2Tx surfaces

Abstract

At present, searching for efficient methods to degrade sulfur hexafluoride (SF6) is a worldwide hotspot. Due to the abundant active groups on the surface, MXene is regarded as an ideal catalyst support. In this paper, the potential active sites of Ti3C2Tx (T = OH, F, O) for SF6 degradation were studied using density functional theory (DFT) method. The results show the adsorption of SF6 on Ti3C2(OH)2 is significantly stronger than that on Ti3C2F2 and Ti3C2O2. Among typical adsorption sites on Ti3C2(OH)2, SF6 exhibited the strongest interaction at OH-1 site. Complex electron orbital interactions occurred between SF6 and Ti3C2(OH)2. Adsorption energy reached −6.739 eV and about 1.414e transferred from Ti3C2(OH)2 to SF6. Structure of SF6 changed obviously and chemical adsorption occurred in this process. However, on Ti3C2F2 and Ti3C2O2, gas–solid interactions were weak and the structures had little change, which was mainly physical adsorption. Compared with common catalysts such as Ag, α‑Al2O3 and BaTiO3, Ti3C2(OH)2 showed better catalytic activity for SF6 degradation. By strong adsorption of the active site on the surface, the degradation products were separated from each other, which weakened SF6 recombination and promoted the further degradation. The results provide theoretical support for MXene acting as a catalyst to efficiently degrade SF6.