High dispersion of γ-MnO2 on well-aligned carbon nanotube arrays and its application in supercapacitors

The well-aligned carbon nanotube arrays (ACNTs) were used as supporting material and the gamma-MnO2/ACNT electrode with high dispersion of gamma-MnO2 has been prepared by electrochemically induced deposition method. The crystal structure and morphology of the gamma-MnO2/ACNT electrode were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The capacitive properties of gamma-MnO2/ACNT electrode were characterized by cyclic voltammetry and galvanostatic charge-discharge method. The specific capacitance of the gamma-MnO2/ACNT electrode is as high as 784 F g(-1) based on gamma-MnO2 and 234 F g(-1) based on gamma-MnO2/ACNT composites in 0.1 M Na2SO4 aqueous solution from 0 to 1 V when the charge-discharge current density is 1 mA cm(-2). Additionally, the electrode shows excellent power characteristics, high electrochemical reversibility and excellent long-term charge-discharge cycle stability. (C) 2008 Elsevier B.V. All rights reserved.