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

• Published in: Electrochimica acta Vol. 51; no. 17; pp. 3417 - 3428
• Main Authors: Horvat-Radošević, V., Kvastek, K., Kraljić-Roković, M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 25.04.2006; Elsevier
• Subjects: Chemistry; Electrochemical impedance spectroscopy; Electrochemistry; Electrodes: preparations and properties; Exact sciences and technology; General and physical chemistry; Other electrodes; Poly( o-ethoxyaniline); Polyaniline; Polymer film modified Pt; “Distributed” model; “Homogeneous” model; Polymer film modified Pt; “Homogeneous” model; Polyaniline; “Distributed” model; Poly( o-ethoxyaniline); Electrochemical impedance spectroscopy; Electrode impedance; Distributed model; Homogeneous model; Electrode production; Aromatic polymer; Transition metal; Experimental study; Bode diagram; Electrochemical characteristic; Conducting polymers; Complex impedance; Platinum; Poly(o-ethoxyaniline); Sheet electrode; Electrode capacity; Aniline polymer; Modified material
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2005.09.037

Impedance spectra of potentiodynamically formed polyaniline (PANI) and poly( o-ethoxyaniline) (POEA), thin film modified Pt electrodes measured at potentials of conductive, emeraldine form in H 2SO 4 electrolyte solution were reported. Specific features of spectra obtained for films of different voltammetric charge densities were modelled and interpreted according to “homogeneous” and “distributed” impedance models. The values of charging capacitances of different PANI and POEA films were found independent of the model used. Charging of polymer films was in terms of both models controlled by charge transport processes being ion diffusion and migration in the first case, and polymer film and ionic conductivities in the second case. Distortion from Warburg-like response 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 that “homogeneous” model was more appropriate for POEA films while “distributed” model was more appropriate for PANI films, at least if both films were formed and measured in presently described conditions.