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Nano-SnO 2 powder was prepared by the hydrothermal method in this paper. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the composition of the crystalline phase and the morphology of the prepared gas-sensitive materials, respectively. In particular, the study focused on the sensing behaviors of nano-SnO 2 -based sensor towards power transformer fault gases such as hydrogen and carbon monoxide. The optimum working temperature for hydrogen and carbon monoxide is about 400 • C and 360 • C, separately. Further investigations into the adsorption process of gas molecule on SnO 2 (110) surface based on the first principles were conducted. The calculations indicated that 1σ orbits of H 2 split into several new electronic peaks and 5σ orbits of CO almost degenerated completely in the adsorption process, which promoted charge transfer between gas molecule and SnO 2 (110) surface. It provides a qualitative explanation for the prepared nano-SnO 2 -based sensor exhibiting different gas sensing properties towards H 2 and CO.

The detection of partial discharge and analysis of the composition and content of sulfur hexafluoride SF6 gas components are important to evaluate the operating state and insulation level of gas-insulated switchgear (GIS) equipment. This paper reported a novel sensing material made of pure ZnO and NiO-decorated ZnO nanoflowers which were synthesized by a facile and environment friendly hydrothermal process for the detection of SF6 decomposition byproducts. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the structural and morphological properties of the prepared gas-sensitive materials. Planar-type chemical gas sensors were fabricated and their gas sensing performances toward the SF6 decomposition byproducts SO2, SO2F2, and SOF2 were systemically investigated. Interestingly, the sensing behaviors of the fabricated ZnO nanoflowers-based sensor to SO2, SO2F2, and SOF2 gases can be obviously enhanced in terms of lower optimal operating temperature, higher gas response and shorter response-recovery time by introducing NiO. Finally, a possible gas sensing mechanism for the formation of the p–n junctions between NiO and ZnO is proposed to explain the enhanced gas response. All results demonstrate a promising approach to fabricate high-performance gas sensors to detect SF6 decomposition byproducts.