Impedance of the Randles Circuit: Redox Reaction (E) at a Rotating Disk Electrode (RDE)
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This Demonstration plots Faradaic () and electrode impedance () for the equivalent circuit (Randles circuit) of the electrochemical redox reaction () at a rotating disk electrode (RDE) in the Nyquist and Bode (modulus and phase) planes.
Contributed by: Jean-Paul Diard and Claude Montella (August 2010)
Open content licensed under CC BY-NC-SA
This Demonstration gives Faradaic () and electrode impedance (Z) for the equivalent circuit (Randles circuit) of the electrochemical redox reaction () at a rotating disk electrode (RDE), taking into account the series ohmic resistance , with
, , , =,
where is the angular frequency. is the charge transfer resistance, the mass transport resistance, the interfacial double capacitance, the time constant of the mass transport, the characteristic frequency of charge transfer, and the characteristic frequency of mass transport.
 J.-P. Diard, C. Montella, and B. Le Gorrec, Cinétique Electrochimique, Paris: Hermann, 1996.
 C. Montella, J.-P. Diard, and B. Le Gorrec, Exercices de Cinétique Electochimique, II Méthodes d'impédance, Paris: Hermann, 2005.
 M. E. Orazem and B. Tribollet, Electrochemical Impedance Spectroscopy, Hoboken, NJ: John Wiley & Sons, 2008.
 Interactive Faradaic Impedance Library, http://www.bio-logic.info/potentiostat/notesifil.html.