▎ 摘　　要

A composite of graphene sheet (GNS) supported by nanotube-like MnO2 nanocrystalline (alpha-MnO2/GNS composites) has been fabricated through a facile one-step hydrothermal method. The nanosized MnO2 particles were homogeneously distributed on GNS, which have been confirmed by transmission electron microscopy analysis (TEM). The structure, composition and electrochemical properties of alpha-MnO2/GNS composites were investigated by means of selective-area electron diffraction (SAED). Fourier transform infrared spectroscopy (FT-IR). X-ray diffraction (XRD), cyclic voltammetry (CV) curves and Galvanostatic charge-discharge curves. alpha-MnO2/GNS composites exhibited a high specific capacitance of 116 F.g(-1) in 1 M Na2SO4 electrolyte. In addition, the alpha-MnO2/GNS composite electrode shows good long-term cycle stability (only 11.99% decrease of the specific capacitance is observed after 1000 charge-discharge cycles). (C) 2012 Elsevier By. All rights reserved.