High-performance asymmetric supercapacitors based on reduced graphene oxide/polyaniline composite electrodes with sandwich-like structure

The sandwich-like structure of reduced graphene oxide/polyaniline （RGO/PANI） hybrid electrode was prepared by electrochemical deposition. Both the voltage windows and electrolytes for electrochemical deposition of PANI and RGO were optimized. In the composites, PANI nanofibers were anchored on the surface of the RGO sheets, which avoids the re-stacking of neighboring sheets. The R（;O/PANI composite electrode shows a high specific capacitance of 466 F/g at 2 mA/cm2 than that of previously reported RGO/PANI composites. Asymmetric flexible supercapacitors applying RGO/PANI as positive electrode and carbon fiber cloth as negative electrode can be cycled reversibly in the high-voltage region of 0-1.6 V and displays intriguing performance with a maximum specific capacitance of 35.5 mF cm^-2. Also, it delivers a high energy density of 45.5 mW h cm^-2 at power density of 1250 mW cm^-2. Furthermore, the asymmetric device exhibits an excellent long cycle life with 97.6Z initial capacitance retention after 5000 cycles. Such composite electrode has a great potential for applications in flexible electronics, roll-up display, and wearable devices.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.

Facile NiCo_(2)S_(4)/C nanocomposite: an efficient material for water oxidation

The water oxidation in alkaline media is a kinetically sluggish process and it requires an active electrocatalyst for overall water splitting which is a challenging task to date.Herein,we formulate a platform for the design of efficient NiCo_(2)S_(4)/C nanocomposite using earth abundant and nonprecious materials.The nanocomposites are prepared by scale up hydrothermal method using different carbon contents from acid dehydrated sucrose.They are structurally and morphologically character-ized by various analytic techniques.The scanning electron microscopy has shown few microns flower-like morphology of nanocomposite and hexagonal crystalline phase is identified by X-ray diffraction(XRD).Further,high-resolution transmission electron microscopy supported the XRD results,and C,Ni,Co and O elements were found in the composition nanocomposite as investigated by energy-dispersive spectroscopy.The most active nanocomposite reaches a current density of 20 mA·cm^(−2) at potential of 285 mV vs reversible hydrogen electrode.The nanocomposite is kinetically supported by 61 mV·dec^(−1) as small Tafel slope.The nanocomposite is stable and durable for 40 h.The electrochemical impedance spectroscopy described a small charge transfer resistance of 188.4Ω.These findings suggest that the NiCo_(2)S_(4)/C nanocomposite could be used as a promising material for an extended range of applications particularly in energy technology.