Sensing performance of CdPc monolayer toward the SF6 decomposition gases: A DFT study

Abstract

The rapid and effective detection of SF6 decomposition species is beneficial to diagnose the faults type and severity of gas insulated switchgear (GIS). In this work, the adsorption behaviors of SF6 decomposition products (HF, H2S SO2, SOF2 and SO2F2) on the Cd decorated phthalocyanine (CdPc) monolayer were systematically studied by using the first-principles calculations, the electronic properties of different adsorption systems and their sensing characteristics were also discussed in detail. The results show that the CdPc monolayer is both thermodynamically and dynamically stable, the H2S and SO2 are all chemically adsorbed on the CdPc monolayer, but the large adsorption strength restrict its application in gas sensor. By contrast, the CdPc monolayer has the appropriate adsorption strength for HF, SOF2 and SO2F2 gases with the Wads of −0.60 to −0.71 eV, as proved by the analysis of charge transfer, charge density difference and density of state. Besides, the work function of CdPc monolayer undergoes remarkable change after HF, SOF2 and SO2F2 adsorption, and the corresponding recovery time is predicted to be 0.01 s, 1.01 s and 0.46 s at room temperature. Therefore, CdPc monolayer has a great potential to be a chemi-resistive material with high sensitivity for HF, SOF2 and SO2F2 detection in GIS.