Detection of SF6 decomposition gases by the pristine and Fe-doped porphyrin based on the first-principles calculations

Abstract

The development of high-performance sensing materials for detecting or removing SF6 decomposition gases is crucial for gas-insulated switchgear (GIS). In this work, the adsorption characteristics of the pristine porphyrin (Pr) and Fe-doped porphyrin (FePr) monolayers towards SF6 decomposition gases were investigated using the first-principles calculations. Additionally, the electronic properties and sensing-mechanism were also examined. The findings indicate that both Pr and FePr monolayers exhibit thermodynamic stability. The intrinsic Pr monolayer only exhibits a moderate affinity towards the SO2 molecule, however, its poor sensitivity of the Pr monolayer renders it unsuitable as the sensing-material. In contrast, the FePr monolayer exhibits favorable adsorption strength towards all five toxic gases (H2S, SO2, SOF2, SO2F2, HF). The FePr monolayer exhibits chemisorption towards SO2/SOF2 gases. Furthermore, the microscopic mechanism of gas-substrate interaction is elucidated through the analysis of charge density difference, charge transfer and density of states. The FePr has excellent sensitivity for H2S, SO2, SO2F2, SOF2 and HF molecules owing to the significant variations of the band gap, electrical conductivity and work function. The recovery time of H2S, SO2, and SOF2 is 12.6 μs (298 K), 0.185 s (398 K) and 15.4 s (298 K), respectively. Our calculated results can offer theoretical guidance for the practical application of FePr-based sensing materials to detect SF6 decompositions gases.