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Journal of the Electrochemical Society, Vol.154, No.11, A987-A992, 2007
Effect of pore structure on the electrochemical capacitive performance of MnO2
Three types of porous MnO2: ordered mesoporous beta-MnO2(OMMnO2), disordered mesoporous gamma-MnO2(DMMnO2), and disordered porous alpha-MnO2(DPMnO2) were synthesized using hard template, self-assembly, co-precipitation methods, respectively. The electrochemical capacitance profiles have been evaluated in 1 M Na2SO4 aqueous solution by means of cyclic voltammetry and impedance measurements. The capacitance profile of the three types of 1D tunnel structure MnO2 is clearly dependent upon its pore structure despite its crystalline structure. The three porous MnO2 deliver a capacitance of 70-90 mu F/cm(2). Compared to the disordered porous MnO2, the ordered mesoporous and disordered mesoporous MnO2, especially for the ordered mesoporous MnO2, shows better rate capability due to the unique structure of their well ordered mesoporous network, which is more favorable for fast ionic transport than in the disordered porous MnO2.