Facile Synthesis of Mesoporous MnCO₃ for Supercapacitor Applications.

We report a rapid and facile synthesis of MnCO3 with uniform mesopores for supercapacitor applications. Mesoporous MnCO3 was synthesised by a co-precipitation method using MnSO4 and (NH4)HCO3 as manganese and carbonate source, respectively. Powder X-ray diffraction study confirmed the formation of rhodochrosite phase of MnCO3. X-ray photoelectron spectroscopic study ascertained the oxidation state of Mn as 2+ in MnCO3. Scanning and Transmission electron microscopic studies revealed that nanograins of size less than 10 nm agglomerated into submicron sized spherical particles of MnCO3. N2 sorption studies displayed a typical type-IV isotherm with H2 hysteresis, demonstrating mesoporosity of as-prepared MnCO3. Furthermore, the mesoporous MnCO3 particles were evaluated for their capacitance properties by cyclic voltammetry and galvanostatic charge-discharge cycling in aqueous 0.1 M Mg(ClO4)2 electrolyte. The fabricated mesoporous MnCO3 electrodes delivered a specific capacitance of 144 F g-1 at a current density of 0.34 A g-1. It also exhibited good rate capability, high reversibility and cyclic stability over 1000 cycles.