3D interconnected MnMoO 4 nanosheet arrays with abundant open spaces and ordered arrangements deposited on nickel foam (NF@MnMoO 4 ) are fabricated by a mild one-step hydrothermal method. As an integrated binder-free electrode for supercapacitors, the optimized NF@MnMoO 4 electrode exhibits a superhigh specific capacitance of 4609 F g −1 (640 mAh g −1 ) at a current density of 1 A g −1 , remarkable rate capability (2800 F g −1 (388.89 mAh g −1 ) even at a current density as high as 20 A g −1 ), and outstanding cycling stability (92.4% of the initial specific capacitance after 20,000 cycles). The fabricated NF@MnMoO 4 //AC asymmetric supercapacitors (ASCs) with excellent cycling performance and high Coulombic efficiency achieve an ultrahigh energy density of 107.38 Wh kg −1 at a power density of 801.34 W kg −1 (72.18 Wh kg −1 at a power density of 3987.85 W kg −1 ). As the practical application, the self-charging power packs of commercial solar cells and NF@MnMoO 4 //AC ASCs are demonstrated to power an LED without extra recharging by other devices, indicating their promising applications in self-power energy-harvesting storage systems.
Hydrogen sulfide (H2S) is an important decomposition component of sulfur hexafluoride (SF6), which has been extensively used in gas-insulated switchgear (GIS) power equipment as insulating and arc-quenching medium. In this work, electrospun ZnO-SnO2 composite nanofibers as a promising sensing material for SF6 decomposition component H2S were proposed and prepared. The crystal structure and morphology of the electrospun ZnO-SnO2 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-SnO2 nanofibers and the gas sensing behaviors to H2S gas were systematically investigated. The proposed ZnO–SnO2 composite nanofibers sensor showed lower optimal operating temperature, enhanced sensing response, quick response/recovery time and good long-term stability against H2S. The measured optimal operating temperature of the ZnO–SnO2 nanofibers sensor to 50 ppm H2S gas was about 250°C with a response of 66.23, which was 6 times larger than pure SnO2 nanofibers sensor. The detection limit of the fabricated ZnO–SnO2 nanofibers sensor toward H2S gas can be as low as 0.5 ppm. Finally, a plausible sensing mechanism for the proposed ZnO–SnO2 composite nanofibers sensor to H2S was also discussed.
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