STUDIES ON THE ELECTRODE-KINETICS OF POLYPYRROLE IN AQUEOUS-SOLUTION BY AC-IMPEDANCE MEASUREMENT

Electrode kinetics of PPy(Cl-) film in acidic and neutral solutions has been studied by the a.c. impedance method. The values of the charge transfer resistance and diffusion coefficient of counter-ions in the PPy film depend on the pH value of the solution in contact and on the potential applied. The exchange current density i(o) of the PPy film electrode is 1.15 mA cm-2 and the apparent diffusion coefficient D(app), of the counter-anion is 1.8 x 10(-9) cm2 s-1, in a pH 3, 0.5 M KCl solution at 0.1 V(SCE). Both i(o) and D(app) decrease with decrease of applied potential. In a neutral solution, two redox processes can be distinguished in the a.c. impedance plots.