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Impedance spectroscopy of oxidized polyaniline and poly(o-ethoxyaniline) thin film modified Pt electrodes

Impedance measurements of potentiodinamically formed polyaniline, PANI, and poly(o-ethoxyaniline), POEA, thin film modified Pt electrodes at potentials of conductive, emeraldine form in H2SO4 electrolyte solution are reported. Specific features of impedance spectra of films of different voltammetric charge densities were modelled and interpreted according to "homogeneous" and "distributed" impedance models. In terms of both models charging of both polymer films was controlled by charge transport processes, being ion diffusion and migration in the first case and polymer film and ionic conductivities within the film in the second case. Distortion of Warburg region observed for both polymer films was explained by either differences in relaxation times of diffusion and migration processes, or by impedance of ionic channels with "anomalous" frequency dispersion. There were some discrepancies between theories and results suggesting the conclusion that "homogeneous" model is more appropriate for POEA films, while "distributed" model is more appropriate for PANI films.

electrochemical impedance spectroscopy ; polymer film modified Pt ; polyaniline ; poly(o-ethoxyaniline)

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