Intrinsic and Ag-doped graphdiyne as a two-dimensional material gas sensing detector for the detection of SF6 decomposition products

Detection of SF6 decomposition gas products is very important for determining the type of fault in Gas-insulated substations (GIS). However, semiconductor-type detectors are difficult to achieve ultra-sensitive detection at room temperature. In this work, the adsorption characteristics of intrinsic graphdiyne (GDY) and Ag-doped modified graphdiyne (Ag-GDY) for the main products of SF6 decomposition gas (HF, H2S, SO2, SOF2, SO2F2) are investigated based on the density functional theory (DFT). The doping site optimization, adsorption structure parameters, energy band structure, density of states, electrostatic potential, and HOMO/LUMO energy levels of Ag-GDY were analyzed. The results showed that the energy gap of the system was significantly decreased and the electrical conductivity was significantly improved after Ag doping at the optimum site C2. The intrinsic GDY is not suitable for high-sensitivity sensing detection because it mainly uses physical adsorption for decomposition products. In contrast, there is strong chemisorption between Ag-GDY and the decomposition products through the hybridization and chemical reaction of the Ag-4d orbital with the gas molecular orbital. Ag-GDY as a new two-dimensional material gas detection sensor has good monitoring performance for SF6 decomposition products. These results may provide some inspiration for the development of new efficient gas detection sensor technologies.