EQCM study of redox properties of PEDOT/MnO2 composite films in aqueous electrolytes

Abstract

Electrochemical behavior of poly-3,4-ethylenedioxythiophene composites with manganese dioxide (PEDOT/MnO2) has been investigated by cyclic voltammetry and electrochemical quartz crystal microbalance at various component ratios and in different electrolyte solutions. The electrochemical formation of PEDOT film on the electrode surface and PEDOT/MnO2 composite film during the electrochemical deposition of manganese dioxide into the polymer matrix was gravimetrically monitored. The mass of manganese oxide deposited into PEDOT at different time of electrodeposition and apparent molar mass values of species, involved into mass transfer during cyclic voltammetry of PEDOT/MnO2 composites were evaluated. It was found that during the redox cycling of PEDOT/MnO2 composite films with various MnO2 content the oppositely directed fluxes of counter ions (anions and cations) occur, resulting in a change of the slope of linear parts of the Δf-E plots with changing the mass fraction of MnO2 in the composite film. Rectangular shape of cyclic voltammograms of PEDOT/MnO2 composites with different loadings of manganese dioxide was observed, which is characteristic of the pseudo-capacitive behavior of the composite material. Specific capacity values of PEDOT/MnO2 composites obtained from cyclic voltammograms were found of about 169 F g-1. The specific capacity, related to the contribution of manganese oxide component, was about 240 F g-1 .

Electrochemical quartz crystal microbalance study of magnesium porphine electropolymerization process

“…Important information on such electroactive polymers and polymer-containing composites is provided by the technique of electrochemical quartz crystal microbalance (EQCM) which may be applied under in situ electrochemical conditions. This method has been used for studies of the film deposition and discharge processes of such polymers as polypyrrole [1][2][3][4][5][6], polythiophene [7], polyaniline [8], in particular the one synthesized under conditions of the cathodic oxygen reduction [9], poly(o-methoxyaniline) [10], poly(o-toluidine) [11], polyparaphenylene [12], 3,4-polyethylenedioxythiophene [13][14][15][16], and poly-3-octylthiophene [17] as well as metal-or metal-oxide-based polymeric nanocomposites [18][19][20][21][22][23][24]. The technique has also been employed for studies of adsorption and desorption process for various gases and ions on electrode surfaces [25][26][27].…”