Synthesis of Template Free Morphology Controlled α-MnO2 Nanorod and Electrochemical Capacitive Study of its RGO Nanocomposite

In this research, α-MnO2 nanorod was synthesized by a novel morphology controlled hydrothermal method in the absence of mold for electrochemical energy storage. Graphite oxide (GO) was synthesized using the modified Hummers method. The oxygenated groups of GO were eliminated by the use of hydrazine to produce the reduced graphene oxide (RGO). Nanocomposites with different percentages were made with reduced graphene oxide (G) and manganese dioxide (M) (G20M80, G40M60, G80M20) and were characterized successfully with appropriate methods. To investigate the electrochemical capacitor behavior of various samples, cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) experiments were performed in a three-electrode system containing 0.5 M Na2SO4 solution as the electrolyte. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) study in 10 mM K4Fe(CN)6 containing 0.1 M KCl also investigated to evaluate the surface properties of the electrodes. The results of the electrochemical experiments showed that the G40M60 electrode had the lowest resistance to charge transfer and ionic diffiution. The results of electrochemical tests revealed excellent supercapacitor behavior of G40M60 nanocomposite and high stability of 91% after 50 charge-discharge cycles at 5 Ag-1 current density. The specific capacitance for the G40M60 nanocomposite was higher than that of other samples and was calculated as 179.72 F.g-1 in current density of 0.6 A.g-1.