DFT study of SF6 decomposed products on Pd-TiO2: gas sensing mechanism study

Detecting the species and concentrations of SF6 decomposed products is crucial for on-line monitoring the running status of SF6-insulated equipment. TiO2-based gas sensing material shows a great potential in SF6 decomposed products detection. In order to improve the sensitivity and selectivity of TiO2-based gas sensing material, Pd atom modified TiO2 (Pd-TiO2) was proposed to analyze its adsorption properties to three characteristic decomposition products of SF6: SO2, SOF2, and SO2F2. The results show that Pd-TiO2 possesses strong adsorption property to these gas molecules because of the high chemical activity of the doped Pd atom. Density of states, differential charge density, and molecular orbits are studied to analyze the gas sensing mechanism of Pd-TiO2 to the gas molecules. It is found that gas molecules adsorption raises an increase of conductivity to different extents, which can be applied to identify the species and concentrations of SF6 decomposed products under electric discharge. Therefore, Pd-TiO2 can be a promising gas sensing material using in SO2, SOF2 and SO2F2 detection with high selectivity and sensitivity. This plays an important role in the detection of SF6 decomposition gas.