ELECTROCHEMICAL PROPERTIES AND ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY OF POLYPYRROLE-COATED PLATINUM ELECTRODES
Polypyrrole (PPy) films of different thickness were characterized by electrochemical impedance
spectroscopy (EIS) measurements in acetonitrile and aqueous solutions, containing 0.1 M NaClO4 or sodium
dodecylsulfate as the dopant. The PPy films were electrochemically deposited on Pt, and their electrochemical
properties studied by cyclic voltammetry. Impedance spectra were obtained at potentials ranging from 0 to 0.8
V/SCE. The EIS data were fitted using two different equivalent electrical circuits (depending on the nature of the
dopant). They involve a diffusive capacitance, which increased with the passing charge during electrosynthesis
(i.e. film thickness) for ClO4
--doped PPy, but was practically unaffected by the film thickness in the case of SDSdoped
PPy. Also, a double-layer capacitance was found only in the circuit of ClO4
--doped PPy. It increased with
the film thickness, and showed a minimum near the open-circuit potential. Finally the charge-transfer resistance
(Rct) obtained with SDS is nearly 200-fold higher than that obtained with ClO4
- in the same solvent (H2O). With
the same dopant (ClO4
-), Rct is about five times higher in acetonitrile relative to water. All these EIS results of the
different types of PPy suggest a relation with the wettability of the polymer.
Auteur(s) : ELECTROCHEMICAL PROPERTIES AND ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY OF POLYPYRROLE-COATED PLATINUM ELECTRODES M. Falla*, A.A. Diagne a, M. Guène a,
Pages : 279-293.
Année de publication : 2006
Revue : Bull. Chem. Soc. Ethiop.
N° de volume : 20(2)
Type : Article
Mise en ligne par : GUENE Makhtar