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The reduced graphene oxide (RGO)/bisphenol A (BPA) composites were prepared by an adsorption-reduction method. The composites are characterized by X-ray diffraction (XRD), UV-vis, thermogravimetric (TG) analysis, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM). The results confirm that BPA is adsorbed on the basal plane of RGO by π-π stacking interaction. Furthermore, the electrochemical behaviors were evaluated by cyclic voltammetry, galvanostatic charge/discharge techniques and electrochemical impedance spectroscopy (EIS). The results show that the RGO/BPA nanocomposites exhibit ultrahigh specific capacitance of 466 F·g−1 at a current density of 1 A·g−1, excellent rate capability (more than 81% retention at 10 A·g−1 relative to 1 A·g−1) and superior cycling stability (90% capacitance decay after 4000 cycles). Consequently, the RGO/BPA nanocomposites can be regarded as promising electrode materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

In the present work Mn3O4/reduced graphene oxide hydrogel (Mn3O4-rGOH) with three dimensional (3D) networks was fabricated by a hydrothermal self-assembly route. The morphology, composition, and microstructure of the as-obtained samples were characterized using powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry analysis (TG), atomic absorption spectrometry (AAS), field emission scanning electron microscopy (FESEM) and transmission electron microscope (TEM). Moreover, the electrochemical behaviors were evaluated by cyclic voltammogram (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). The test results indicated that the hydrogel with 6.9% Mn3O4 achieved specific capacitance of 148 F·g−1 at a specific current of 1 A·g−1, and showed excellent cycling stability with no decay after 1200 cycles. In addition, its specific capacitance could retain 70% even at 20 A·g−1 in comparison with that at 1 A·g−1 and the operating window was up to 1.8 V in a neutral electrolyte. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) material, as a promising candidate for supercapacitor electrodes, draws great attention all the time since it exhibits the enhanced capacitive performance comparing with the low dimensional nanoscale building blocks. Herein, we grow MnOOH on carbon cloth (CC) fibers by employing electrodeposition method. The morphology, microstructure and composition of the as-obtained samples were characterized by using FESEM, XRD, XPS, Raman and FTIR. The MnOOH nanosheets are grown vertically on CC fibers to form a thin-wall cell structure with open pores (donated as thin-wall MnOOH/CC), which can be directly acted as working electrode without other binders or conductive additions. The thin-wall MnOOH/CC electrode in the three-electrode configuration reveals a high specific capacitance of 330.2 F g −1 under a wide potential window of 1.7 V (ranging from −0.9 V to 0.8 V) as well as excellent cycle stability (6.3% decay after 5000 cycles). Furthermore, the symmetric supercapacitor (SSC) assembled by using thin-wall MnOOH/CC as both negative and positive electrodes shows an energy density of 32.5 Wh kg −1 at power density of 850 W kg −1 with a remarkable cycle lifetime (84.6% of the initial value after 10000 cycles). The unique thin-wall structure and binder-free electrode are responsible for the enhanced electrochemical performances. [ABSTRACT FROM AUTHOR]

Synthesis of nickel oxide (NiO) nanomaterials with well-controlled morphologies is crucial to obtain superior electrochemical properties. Herein, we present a facile solvothermal route for the fabrication of three different morphologies NiO containing particles, honeycomb and three-dimensional (3D) nanoflower by adjusting the solvothermal reaction time. The possible mechanism for the formation process of the hierarchical 3D nanoflower architecture is investigated and proposed. The morphology and crystal structure of the as-prepared NiO were characterized by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TG), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and the Brunauer–Emmett–Teller method (BET). The effects of morphologies on the electrochemical performances were systematically studied. It was found that NiO with flower-like structure exhibited the highest specific capacitance (364 F g −1 at 1 A g −1 ), excellent rate capability (64% capacitance retention from 1 A g −1 to 10 A g −1 ) and excellent cycling stability (no decrease in specific capacitance after 1200 test cycles). [ABSTRACT FROM AUTHOR]