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Analysis of electrochemical impedance of polyaniline films prepared by galvanostatic, potentiostatic and potentiodynamic methods

Mondal, Sujit Kumar and Prasad, Rajendra K and Munichandraiah, N (2005) Analysis of electrochemical impedance of polyaniline films prepared by galvanostatic, potentiostatic and potentiodynamic methods. In: Synthetic Metals, 148 (3). pp. 275-286.

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Abstract

Polyaniline (PANI) films have been deposited on stainless steel (SS) substrate by galvanostatic, potentiostatic and potentiodynamic methods. Electrochemical impedance spectra of the electrodes have been analyzed using a transmission line model consisting of two rails of finite resistances. The impedance spectra of the galvanostatically prepared electrodes are similar in shape to those of potentiostatically grown electrodes. The resistance of aqueous pore $(R_{aq})$ due to ionic doping–dedoping process is greater than the resistance $(R_p)$ of electronic chargetransfer on polymer chain. These parameters exhibit an increase in magnitude with thickness of PANI, as expected from the transmission line theory. The shape of impedance spectra of potentiodynamically grown PANI, however, is different and its $R_{aq} \leq R_p$. The impedance parameters of potentiodynamically prepared PANI/SS electrodes have been found to depend on the sweep rate used for the deposition of PANI. Several possible explanations have been discussed to understand the influence of sweep rate during deposition on impedance parameters of the electrodes. In contrast to the behavior of PANI deposited by galvanostatic and potentiostatic methods, $R_p$ decreases with an increase in thickness of PANI deposited by the potentiodynamic method. The effect of concentration of aniline used for the deposition of PANI on impedance parameters has also been studied. The results of capacitance of PANI obtained from the ac impedance studies have been found to be comparable with those obtained from the cyclic voltammetric studies.

Item Type: Journal Article
Additional Information: The Copyright belongs to Elsevier.
Keywords: Polyaniline;Impedance;Transmission line model;Capacitance;Electronic resistance;Ionic resistance
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 17 Mar 2006
Last Modified: 19 Sep 2010 04:24
URI: http://eprints.iisc.ernet.in/id/eprint/5837

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