Chronoamperometric response to potentiostatic doping at polypyrrole-coated microdisk electrodes

Chronoamperometric oxidation curves at conducting polymer electrodes were obtained theoretically on the basis of the concept of propagation for a conductive domain of the polymer. The theory predicted the appearance of a peak and an exponential decay. The time at the peak was proportional to the thickness of the film. Chronoamperometric doping curves of polypyrrole were measured at a polypyrrole-coated microdisk electrode for various thicknesses of the film. The curve exhibited a peaked wave rather than a monotonic decay. The peak height increased linearly with the stepped potential. The peaked wave included mainly the capacitive current and partly the faradaic current for oxidation of the polypyrrole. The Chronoamperometric curve after the peak decayed exponentially with time. The peak time was proportional to the thickness of the film, and the logarithmic peak time varied linearly with the potential. These variations are explained by the propagation theory.