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The Apparent Constant-Phase-Element Behavior of a Disk Electrode with Faradaic Reactions

Huang, Vicky Mei-Wen and Vivier, Vincent and Orazem, Mark E. and Pébère, Nadine and Tribollet, Bernard The Apparent Constant-Phase-Element Behavior of a Disk Electrode with Faradaic Reactions. (2007) Journal of The Electrochemical Society (JES), vol. 154 (n° 2). C99-C107. ISSN 0013-4651

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Official URL: http://dx.doi.org/10.1149/1.2398894

Abstract

Geometry-induced current and potential distributions modify the global impedance response of a disk electrode subject to faradaic reactions. The problem was treated for both linear and Tafel kinetic regimes. The apparent capacity of a disk electrode embedded in an insulating plane was shown to vary considerably with frequency. At frequencies above the characteristic frequency for the faradaic reaction, the global impedance response has a quasi-constant-phase element (CPE) character, but with a CPE coefficient alpha that is a function of both dimensionless frequency K and dimensionless current density J. For small values of J, alpha approached unity, whereas, for larger values of J, alpha reached values near 0.78. The calculated values of alpha are typical of those obtained in impedance measurements on disk electrodes. For determining the interfacial capacitance, the influence of current and potential distributions on the impedance response cannot be neglected, even if the apparent CPE exponent alpha has values close to unity. Several methods taken from the literature were tested to determine their suitability for extracting interfacial capacitance values from impedance data on disk electrodes. The best results were obtained using a formula which accounted for both ohmic and charge-transfer resistances.

Item Type:Article
Additional Information:Thanks to Electrochemical Society editor. The definitive version is available at http://scitation.aip.org The original PDF of the article can be found at Journal of The Electrochemical Society website : http://www.ecsdl.org/JES/
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution: Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Other partners > University of Florida (USA)
Other partners > Université Pierre et Marie Curie, Paris 6 - UPMC (FRANCE)
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
French research institutions > Centre National de la Recherche Scientifique - CNRS
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Deposited By: Celine Cabaup

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