Preparation and Properties of γ-MnO2 Nanotubes as Electrode Materials of Supercapacitor

gamma-MnO2 nanotubes have been successfully synthesized by chemically depositing manganese hydroxide in anodic aluminum oxide (AAO) templates and thermally annealing at 500 degrees C. The synthesized nanotubes have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption-desorption isotherm analysis. The electrochemical capacitance behavior of the gamma-MnO2 nanotubes electrode was investigated by cyclic voltammetry and galvanostatic charge-discharge studies in 1 mol/L Na2SO4 solution. The electrochemical data demonstrate that the gamma-MnO2 nanotubes display good capacitive behavior with a high specific capacitance of 566 F/g at a current density of 100 mA/g and a good specific capacitance retention of ca. 90% after 1000 continuous charge-discharge cycles, indicating that the gamma-MnO2 nanotubes can be promising electroactive materials for supercapacitor.