Effect of thermal annealing on the structural, morphological and super capacitor behavior of MnO2 nanocrystals

Precursors of nanosized manganese dioxide were prepared through a chemical precipitation method. The synthesized precursors of MnO2 were subjected to thermo gravimetric analysis. The thermal analysis results showed the MnO2 formation at 500 °C. To study the effect of thermal treatments on the capacitive behavior of MnO2, the precursors were annealed at different temperatures (300, 400 and 500 °C). The annealed products were characterized by X-ray diffraction (XRD), Fourier transforms infra-red spectroscopy (FT-IR) and cyclic Voltammetry (CV) analysis. Among the annealed products, MnO2 annealed at 400 °C exhibits high specific capacitance. The morphologies of the products annealed at 400 and 500 °C were analyzed by a scanning electron microscope (SEM) and atomic force microscopy (AFM). The sample annealed at 500 °C shows spherical morphology with the inclusion of nanorods. To confirm the morphology of the annealed products, field emission transmission electron microscope (FE-TEM) measurements were carried out.