Investigating the Gas-sensitive Response of Graphene doped by Different TiO2 Concentrations towards SF6 Decomposition Products

SF6 gas will decompose four characteristic decomposition products (H2S, SO2, SO2F2 and SOF2) when an insulation failure occurs early in SF6 gas-insulated equipment. By building gas-sensitive sensors into insulation devices it is possible to detect the characteristic gases of insulation faults. In this paper, we use Graphene which is available with good gas sensitivity, as a substrate and then improve the gas response of Graphene by doping with TiO2 clusters. The adsorption mechanism of (TiO2)n-Graphene (n = 1–4) on four characteristic decomposition gases is firstly analyzed based on first principles, and then verifies experimentally. (TiO2)n-Graphene (n = 1–4) shows the largest change in Eg after adsorption of SO2 gas with 61.70%, 1.07%, 23.19% and 64.04%, respectively. The SEM characterization shows that Graphene has an obvious lamellar structure, and TiO2 nanoparticles are mainly distributed on the outer wall of Graphene, which has a large curvature and strong surface activity. The gas-sensitive response values of the (TiO2)n-Graphene (n = 1–4) sensor for different gases at the same gas concentration are ranked as SO2 > H2S > SO2F2 > SOF2. The results show that TiO2 cluster-doped Graphene is a potential gas-sensitive sensing material that can be a new material for online monitoring of faulty gas content in SF6 gas-insulated equipment.