The capacitive properties of amorphous manganese dioxide electrodeposited on different thermally-treated carbon papers

The surface structure of the commercial carbon paper (CP) has been modified through thermal treatment, and then MnO₂ was electrodeposited on the thermally-treated carbon paper (TTCP) by cyclic voltammetry (CV) method in the phosphate buffer solution (PBS, pH 9.18) containing KMnO₄. The obtained samples were characterized by X-ray diffraction (XRD), X-ray photoelectron energy spectroscopy (XPS) and scanning electron microscopy (SEM). The results showed that the phase of the obtained MnO₂ was amorphous, and that the morphology of the MnO₂ deposited on the substrates was influenced strongly by the substrates. The capacitive properties of MnO₂ deposited on the carbon substrates were investigated by CV, galvanostatic charge/discharge, electrochemical impedance spectroscopy technique. It was found that the specific capacitance of MnO₂ deposited on the optimum TTCP can reach to 749 F g⁻¹ based on the charge/discharge measurement, which was far larger than that on the CP (345 F g⁻¹).