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Journal of Chemistry
Volume 2015 (2015), Article ID 629362, 8 pages
http://dx.doi.org/10.1155/2015/629362
Research Article

Low Temperature Synthesis of MnO2/Graphene Nanocomposites for Supercapacitors

1State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, China
2Hebei Key Laboratory of Applied Chemistry, School of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, China
3National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China

Received 30 September 2014; Revised 12 January 2015; Accepted 1 March 2015

Academic Editor: Lavinia Balan

Copyright © 2015 Hao Huang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

MnO2/graphene nanocomposites were synthesized through a simple route in a water-reflux condenser system. The as-prepared composites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman microscope, and Brunauer-Emmett-Teller surface area analysis. Capacitive properties of the synthesized composite electrodes were investigated via cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectrometry in a 0.5 M Na2SO4 electrolyte. Results show that this method can control the morphology and structure of MnO2 loaded onto the graphene sheets. Because excessive MnO2 enwrapping graphene would affect the overall conductivity, the composite prepared by lower temperature has better characteristics of supercapacitor. 60-MnO2/graphene composite (48 wt% MnO2) displays the specific capacitance as high as 350 F/g at 1000 mA/g, which is higher than that of 100-MnO2/graphene (302 F/g), and it is almost two times higher than that of MnO2 (163 F/g). Furthermore, the composite exhibits excellent long cycle life along with ~93% specific capacitance retained after 5000 cycle tests.