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The detection of oil-dissolved gases (such as CO, CH 4 and H 2) in transformers on-line is an important technology to predict and judge the operating status of transformers. Microstructure and gas sensing performance of Au-MoS 2 microspheres synthesized by hydrothermal method were investigated in the present research. The results indicated Au-MoS 2 based gas sensor has excellent response to CO, CH 4 and H 2 gases with maximum responses of 25.48, 16.75 and 8.48 at 30 ppm in their optimum working temperature (150 °C, 150 °C, 175 °C). In addition, First-principle calculation was carried out to expound the sensing mechanism in detail. The conclusions of this study suggest that Au-MoS 2 monolayer exhibits a promising applicable future in sensor detecting of oil-dissolved gases in power transformer. The hierarchical flower-like Au-MoS 2 microspheres were favoring synthesized using simple hydrothermal method and their microstructure are measured. Gas sensing performance and atomic level gas sensing mechanism of MoS 2 microspheres to CO, CH 4 and H 2 was investigated. We found Au-MoS 2 microspheres gas sensor has good gas sensing performances and Au-MoS 2 monolayer exhibits excellent adsorption capacity to three target gases. Unlabelled Image • The hierarchical flower-like Au-MoS 2 microspheres were synthesized via simple hydrothermal method. • Au-MoS 2 microspheres gas sensor shows good gas sensing properties to CO, H 2 and CH 4. • The excellent adsorption performances of Au-MoS 2 monolayer to CO, H 2 and CH 4 were discussed in detail. • Theoretical studies have been applied to analyze the gas sensing mechanism of Au-MoS 2 microspheres to CO, H 2 and CH 4. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we reported the morphology controllable synthesis of hierarchical WO 3 nanostructures, i.e. nanorods, nanospheres and nanoflowers, via a facile hydrothermal route. All the obtained WO 3 nanostructures were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET), respectively. A possible growth mechanism for the three various nanomaterials was proposed in detail. WO 3 based gas sensors were fabricated with the synthesized nanomaterials and the gas sensing performances to acetylene (C 2 H 2), one of the fault characteristic gases dissolved in power transformer oil, were systematically measured. It was found that the sensor based on nanosheet-assembled nanoflowers with largest surface (56.74 m2g−1) exhibits the highest sensing performance including gas response (32.31) and response-recovery time (12 s, 17 s) to 200 ppm C 2 H 2. The results indicate that WO 3 sensing materials could be a promising choice for synthesizing high-performance C 2 H 2 sensors for the judgement of the early latent faults of the oil immersed transformer. Highlights • WO 3 nanorods, nanospheres and nanoflowers were synthesized via hydrothermal route for detecting C 2 H 2. • The growth mechanism of the synthesized WO 3 nanostructures was proposed. • WO 3 nanoflowers sensor exhibits the most excellent sensing performances to C 2 H 2. [ABSTRACT FROM AUTHOR]