Improved activity of a graphene-TiO2 hybrid electrode in an electrochemical supercapacitor

We present a simple and fast approach for the synthesis of a graphene-TiO2 hybrid nanostructure using a microwave-assisted technique. The microstructure, composition, and morphology were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, Raman microscopy, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy. The electrochemical properties were evaluated using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge tests. Structural analysis revealed a homogeneous distribution of nanosized TiO2 particles on graphene nanosheets. The material exhibited a high specific capacitance of 165 F g(-1) at a scan rate of 5 mV s(-1) in 1 M Na2SO4 electrolyte solution. Theenhanced supercapacitance property of these materials could be ascribed to the increased conductivity of TiO2 and better utilization of graphene. Moreover, the material exhibited long-term cycle stability, retaining similar to 90% specific capacitance after 5000 cycles, which suggests that it has potential as an electrode material for high-performance electrochemical supercapacitors. (C) 2013 Elsevier Ltd. All rights reserved.