Gas-sensing performance of transition-metal surface-modified MnX2 (X = Se, Te) toward SF6 decomposition products (SOF2 and SO2F2): a first-principles study

Abstract

Sulfur hexafluoride (SF₆) is widely used in gas-insulated equipment; however, its decomposition products pose serious threats to the operational safety of such systems. Based on density functional theory calculations, this work systematically investigates the adsorption behaviors, electronic structure modulation, and work function response characteristics of intrinsic and transition-metal (Ti, Cr, Fe, and Co) surface-modified MnX₂ (X = Se, Te) monolayers toward typical SF₆ decomposition gases, SOF₂ and SO₂F₂. The results indicate that intrinsic MnX₂ monolayers exhibit only weak physisorption, which is insufficient to meet the requirements for gas sensing applications. In contrast, transition-metal surface modification significantly enhances the gas–substrate interactions and reconstructs the electronic states near the Fermi level through hybridization of the 3d orbitals. Ti-modified systems induce strong chemisorption and molecular dissociation of SO₂F₂, rendering them suitable for gas capture rather than reversible sensing. By comparison, the Co–MnTe₂ monolayer exhibits a pronounced work function response (0.754 eV) toward SOF₂, along with good selectivity and a microsecond-scale recovery time, demonstrating outstanding potential as a room-temperature work-function-based gas sensing material. By comprehensively considering the adsorption mechanisms, work function responses, and recovery kinetics, this study clearly distinguishes the applicability of different TM–MnX₂ systems for reversible sensing and gas capture of SF₆ decomposition products, providing a theoretical basis for the design and screening of work-function-type gas sensing materials.