Impedance analysis of the transport of counter ions at polypyrrole-Nafion composite electrodes

The ion transport accompanying the redox reactions of polypyrrole at a polypyrrole-Nafion composite electrode was investigated with systems containing specifically selected electrolytes. From the cyclic voltammetric and impedance data obtained, transport of cations was found to be responsible for the charge transfer process and parameters such as the charge transfer resistance, Rct, the low frequency polymer resistance, Re, the limiting capacitance, Ce and the diffusion coefficient, Dct for the related cations were estimated. The electrochemical behaviour (i.e., electronic insulation and electronic conductance) of polypyrrole-Nafion composite electrodes was found to be the same as that of the polypyrrole electrodes, except that they appeared in regions of more negative potentials.