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Hydrogen sulfide (H 2 S) is an important decomposition component of sulfur hexafluoride (SF 6 ), which has been extensively used in gas-insulated switchgear (GIS) power equipment as insulating and arc-quenching medium. In this work, electrospun ZnO-SnO 2 composite nanofibers as a promising sensing material for SF 6 decomposition component H 2 S were proposed and prepared. The crystal structure and morphology of the electrospun ZnO-SnO 2 samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The composition of the sensitive materials was analyzed by energy dispersive X-ray spectrometers (EDS) and X-ray photoelectron spectroscopy (XPS). Side heated sensors were fabricated with the electrospun ZnO-SnO 2 nanofibers and the gas sensing behaviors to H 2 S gas were systematically investigated. The proposed ZnO-SnO 2 composite nanofibers sensor showed lower optimal operating temperature, enhanced sensing response, quick response/recovery time and good long-term stability against H 2 S. The measured optimal operating temperature of the ZnO-SnO 2 nanofibers sensor to 50 ppm H 2 S gas was about 250°C with a response of 66.23, which was 6 times larger than pure SnO 2 nanofibers sensor. The detection limit of the fabricated ZnO-SnO 2 nanofibers sensor toward H 2 S gas can be as low as 0.5 ppm. Finally, a plausible sensing mechanism for the proposed ZnO-SnO 2 composite nanofibers sensor to H 2 S was also discussed.

Tin oxide SnO 2 -based gas sensors have been widely used for detecting typical fault characteristic gases extracted from power transformer oil, namely, H 2 , CO, CO 2 , CH 4 , C 2 H 2 , C 2 H 4 , and C 2 H 6 , due to the remarkable advantages of high sensitivity, fast response, long-term stability, and so on. Herein, we present an overview of the recent significant improvement in fabrication and application of high performance SnO 2 -based sensors for detecting these fault characteristic gases. Promising materials for the sensitive and selective detection of each kind of fault characteristic gas have been identified. Meanwhile, the corresponding sensing mechanisms of SnO 2 -based gas sensors of these fault characteristic gases are comprehensively discussed. In the final section of this review, the major challenges and promising developments in this domain are also given.