<b>Electrochemical properties and electrochemical impedance spectroscopy of polypyrrole-coated platinum electrodes</b>
Polypyrrole (PPy) films of different thickness were characterized by electrochemical impedance spectroscopy (EIS) measurements in acetonitrile and aqueous solutions, containing 0.1 M NaClO<sub>4</sub> or sodium dodecylsulfate as the dopant. The PPy films were electrochemically deposited...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Chemical Society of Ethiopia
2006-12-01
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| Series: | Bulletin of the Chemical Society of Ethiopia |
| Subjects: | |
| Online Access: | http://www.ajol.info/index.php/bcse/article/view/21171 |
| Summary: | Polypyrrole (PPy) films of different thickness were characterized by electrochemical impedance spectroscopy (EIS) measurements in acetonitrile and aqueous solutions, containing 0.1 M NaClO<sub>4</sub> 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 ClO<sub>4</sub><sup>-</sup>-doped PPy, but was practically unaffected by the film thickness in the case of SDS-doped PPy. Also, a double-layer capacitance was found only in the circuit of ClO<sub>4</sub><sup>-</sup>-doped PPy. It increased with the film thickness, and showed a minimum near the open-circuit potential. Finally the charge-transfer resistance (R<sub>ct</sub>) obtained with SDS is nearly 200-fold higher than that obtained with ClO<sub>4</sub><sup>-</sup> in the same solvent (H<sub>2</sub>O). With the same dopant (ClO<sub>4</sub><sup>-</sup>), R<sub>ct</sub> 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. |
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| ISSN: | 1011-3924 1726-801X |