Enhanced electrochemical properties of cobalt doped manganese dioxide nanowires

The various molar concentrations of cobalt doped manganese dioxide (Co-MnO2) nanostructures were synthesized by an hydrothermal technique for electrochemical supercapacitor application. The X-ray diffraction analysis showed that the samples were composed of multiphase of MnO2 with dominant reflections of γ-MnO2 structure of crystallization. The morphological studies displayed the existence of MnO2 nanowires with the width of 10-20 nm and showing a good degree of crystallization. The electrochemical characterization was performed using cyclic voltammetry, galvanostatic charge/discharge test and impedance spectroscopy in 1 M Na2SO4 aqueous electrolyte. All the samples exhibit a typical ideal capacitive behavior with an increasing order of specific capacitance values with respect to the increase in the concentration of cobalt ions up to a certain limit. The specific capacitance of 415 F g−1 was delivered by 5% Co-MnO2 sample at 0.2 A g−1 which was nearly double that of bare MnO2 electrode of 231 F g−1. Moreover, the Co-MnO2 electrode shows an excellent capacitance retention (97.3%) after 5000 charge and discharge cycles.