Low-temperature synthesis of δ-MnO2 with large surface area and its capacitance

delta-MnO2 was synthesized by a facile low-temperature hydrothermal method with a mixed system of KMnO4 and CO(NH2)(2) at 90 degrees C for 24 h. The obtained product was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N-2 adsorption-desorption. Results showed that the as-synthesized product had a layered structure and a high specific surface area of 230 m(2) g(-1). Electrochemical characterization indicated that the prepared material exhibited an ideal capacitive behavior with the initial capacitance value of 265 F g(-1) in 1 mol L-1 Na2SO4 aqueous solution at a scan rate of 5 mV s(-1) and excellent cycling behavior. (C) 2010 Elsevier B.V. All rights reserved.