Tuning the Capacitance Properties of Nanocrystalline MnCO₃by the Effect of a Carbonizing Agent

Nanocrystalline MnCO 3 is synthesized by hydrothermal reduction of KMnO 4 using different amounts of pyrrole. The effect of molar ratio of KMnO 4 :pyrrole on the phase purity, size of the particle, textural and capacitance properties of MnCO 3 is studied systematically using various physico-chemical and electrochemical techniques. While X-ray diffraction studies confirm decline in the phase purity of MnCO 3 , FTIR, Raman spectroscopic and thermogravimetric studies reveal an increase in the amount of adsorbed water and residual carbon content on increasing the pyrrole concentration during the synthesis. An increase in the size of the particles and reduction in the number of mesopores are observed from the morphological and sorption studies on increasing the pyrrole concentration during the synthesis. A highest specific capacitance value of 296 F g −1 is obtained at a current density of 0.16 A g −1 for the nanocrystalline MnCO 3 , and this capacitance value found to decrease on increasing the concentration of pyrrole during the synthesis of nanocrystalline MnCO 3 (166 and 140 F g −1 for the KMnO 4 :pyrrole ratio of 1:1 and 1:2, respectively).