Low-Temperature Detection of Sulfur-Hexafluoride Decomposition Products Using Octahedral Co3O4-Modified NiSnO3 Nanofibers

Sulfur hexafluoride (SF6) is widely used in electrical equipment because of its excellent insulating properties. The type of internal fault in the power system can be identified by detecting SF6 decomposition products. In this manuscript, we report a novel sensing material based on octahedral Co3O4-modified NiSnO3 nanofibers synthesized via a two-step process based on electrospinning followed by a hydrothermal method for detecting the SF6 decomposition products. From the evaluation of various characterization techniques, it was determined that the Co3O4 octahedra adhered inflexibly to the surface of the NiSnO3 nanofibers, which consist of smaller particles and provide a huge surface area for the adsorption of an enormous amount of gas species. Planar-type chemical gas sensors were devised, and their gas detecting performance against SF6 decomposition products was systematically investigated. A comparison of the sensitivity properties of different amounts of charged Co3O4 octahedra in NiSnO3 nanofibers shows that the S-2-based Co3O4@NiSnO3 composite has a high selectivity for 100 ppm SO2F2 gas with a high sensing response of 22.5 at a relatively low temperature of 50 °C with a moderate response/recovery interval (∼200/∼268 s) and a low detection limit (5 ppm) over other interfering gases, such as SOF2, SO2, and H2S. Interestingly, the sensing properties of the fabricated sensors based on the Co3O4@NiSnO3 composites for the SO2F2 gas were improved in terms of lower operating temperatures, higher gas responses, and mild response/recovery intervals, which could be attributed to the unique microstructure effect, the catalytic influence of Co3O4 octahedra, and the creation of p/n junctions to increase the charge transfer and diffusion rate within the catalytic assembly of the sensor materials. This work highlights the importance of the heterostructure design in the construction of high-performance gas sensors for the real-time detection of SF6 decomposition products.