Facile synthesis of reduced graphene oxide/CoWO4 nanocomposites with enhanced electrochemical performances for supercapacitors

A facile one-pot hydrothermal method was provided for synthesis of the reduced graphene oxide-cobalt tungstate (RGO/CoWO4) nanocomposites with the enhanced electrochemical performances for supercapacitors for the first time. The resulting nanocomposites are comprised of CoWO4 nanospheres that are well-anchored on graphene sheets by in situ reducing. The prepared RGO/CoWO4 nanocomposites have been thoroughly characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, Thermogravimetric analysis, Scanning electron microscopy, Transmission electron microscopy, X-ray photoelectron spectroscopy, and N-2 adsorption-desorption. Importantly, the prepared nanocomposites exhibit superior electrochemical performance to CoWO4 as electrodes for supercapacitors. As a result, RGO/CoWO4 nanocomposites with 91.6 wt% CoWO4 content achieved a specific capacitance about 159.9 F g(-1) calculated from the CV curves at 5 mV s(-1), which was higher than that of CoWO4 (60.6 F g(-1)). The good electrochemical performance can be attributed to the increased electrical conductivity and the creation of new active sites due to the synergetic effect of RGO and CoWO4 nanospheres. The cyclic stability tests demonstrated capacitance retention of about 94.7% after 1000 cycles, suggesting the potential application of RGO/CoWO4 nanocomposites in energy-storage devices. (C) 2014 Elsevier Ltd. All rights reserved.