Facile synthesis of α-MnO2 one-dimensional (1D) nanostructure and energy storage ability studies

The dense manganese oxide nanorods with an extremely narrow distribution are synthesized at a low temperature using first cathodic electrodeposition subsequently heat treatment. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images show that the nanorods have bar shapes, and their average diameter is less than 50 nm. The Fourier transform infrared (FT-IR) study, the selected area electron diffraction (SAED) pattern in TEM images and the X-ray diffraction (XRD) result show that the nanorods are α-MnO2 single crystal. The results of N2 adsorption–desorption analysis indicate that the BET surface area of the α-MnO2 nanorods is 93 m2 g−1. By recording the potential–time curve during the electrodeposition process, it is revealed that water reduction reaction has a major role in the electrogeneration of base at the cathode surface under the applied electrochemical conditions. Finally, based on the H2 bubbling on the cathode surface, the mechanism of the formation and the growth of α-MnO2 nanorods are proposed and discussed. For the electrochemical supercapacitor application, electrochemically prepared α-MnO2 is found to be stable for a large number of cycles with high specific capacitance, 338 F g−1 at a scan rate of 10 mV s−1. Finally, the charge–discharge mechanism is discussed.