IMPEDANCE ANALYSIS OF CHARGE-TRANSPORT AND REDOX REACTIONS OF POLYPYRROLE AT POLYPYRROLE-COATED ELECTRODES

Charge transport accompanying the redox reactions of polypyrrole at a polypyrrole-coated electrode was investigated with systems containing selected electrolytes. From cyclic voltammetric and impedance data we found transport of anions into and from the polymer film to be responsible for the charge-transfer process accompanying the oxidation and reduction of polypyrrole. With parameters such as charge-transfer resistance, R(ct), low-frequency polymer resistance, R(l), limiting capacitance, C-l and diffusion coefficient, D-ct estimated, the electrochemical behaviour of polypyrrole as an electronic insulator and conductor is explicitly identified.