Electrochemical Properties of Composite Electrodes, Prepared by Spontaneous Deposition of Manganese Oxide into Poly-3,4-ethylendioxythiophene

In the present work, a simple cost-effective method of synthesis of composite PEDOT/MnO2 with dispersed manganese oxide particles was investigated. The composites were obtained by spontaneous reduction of permanganate ions in contact with PEDOT film. The morphology of highly dispersed manganese oxide in PEDOT film was characterized by SEM. XPS spectroscopy was employed for identification of valence states of manganese in composites at different oxidation states. FTIR spectra also confirm the presence of MnO2 in the composite.Electrochemical properties of composites, obtained with variation of synthesis conditions, were investigated using cyclic voltammetry and electrochemical impedance spectroscopy. The capacitive parameters of composites with different ratio between PEDOT and MnO2 layers were systematically investigated and analyzed. Specific capacitance of composites Cs,PEDOT/MnO2 was in the range of 148–221 F g−1 and increased with the increase of MnO2 loading (from 27 to 72 wt%) into PEDOT film. The calculated values of capacitance related to contribution of manganese oxide Cs,MnO2 were in the range 274–310 F g−1.The enhanced capacitive properties of composites can be mainly attributed to 3-D distribution of disperse MnO2 in the porous structure of PEDOT film with high surface area. The presence of conducting porous matrix facilitates ion diffusion and electron transfer, leads to the lowering the internal resistance of composite material and improves the electrochemical utilization of manganese oxide. The stability of composite materials was shown by means of long-term cycling, where the low reduction in capacitance values was observed.