Electrochemical capacity retention of nearly X-ray amorphous nanostructured manganese oxide (nanoMnO 2 ) synthesized by mixing directly KMnO 4 with ethylene glycol under ambient conditions for supercapacitor studies is enhanced significantly. Although X-ray diffraction (XRD) pattern of nanoMnO 2 shows poor crystallinity, it is found that by Mn K-edge X-ray absorption near edge structure (XANES) measurement that the nanoMnO 2 obtained is locally arranged in a δ-MnO 2 -type layered structure composed of edge-shared network of MnO 6 octahedra. Field emission scanning electron microscopy and XANES measurements show that nanoMnO 2 contains nearly spherical shaped morphology with δ-MnO 2 structure, and 1D nanorods of R-MnO 2 type structure (powder XRD) in the annealed (600 °C) sample. Volumetric nitrogen adsorption-desorption isotherms, inductively coupled plasma analysis, and thermal analysis are carried out to obtain physicochemical properties such as surface area (230 m 2 g -1 ), porosity of nanoMnO 2 (secondary mesopores of diameter 14.5 nm), water content, composition, etc., which lead to the promising electrochemical properties as an electrode for supercapacitor. The nanoMnO 2 shows a very high stability even after 1200 cycles with capacity retention of about 250 F g -1 .

Nanostructured MnnormalO2 was synthesized at ambient condition by reduction of potassium permanganate with aniline. Powder X-ray diffraction, thermal analysis (thermogravimetric and differential thermal analysis), Brunauer–Emmett–Teller surface area, and infrared spectroscopy studies were carried out for physical and chemical characterization. The as-prepared MnnormalO2 was amorphous and contained particles of 5–10nm diameter. Upon annealing at temperatures 400°C , the amorphous MnnormalO2 attained crystalline α-phase with a concomitant change in morphology. A gradual conversion of nanoparticles to nanorods is evident from scanning electron microscopy and transmission electron microscopy (TEM) studies. High-resolution TEM images suggested that nanoparticles and nanorods grow in different crystallographic planes. Capacitance behavior was studied by cyclic voltammetry and galvanostatic charge–discharge cycling in a potential range from −0.2to1.0V vs SCE in 0.1M sodium sulfate solution. Specific capacitance of about 250Fnormalg−1 was obtained at a current density of 0.5mAcm−2 (0.8Anormalg−1) .

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