Ideally polarizable electrode

Ideally polarizable electrode (also ideal polarizable electrode or ideally polarized electrode), in electrochemistry, is an electrode characterized by an absence of net current between the two sides of the electrical double layer, i.e., no faradic current between the electrode surface and the electrolyte. Any transient current that may be flowing is considered non-faradaic.[1]

Ideally polarizable electrode is contrasted with ideally non-polarizable electrode, for which a faradic current can freely pass (without polarization). A polarizable electrode ideally has no DC current flow between the electrode and the surrounding electrolyte. It shows a very large change in potential upon passage of small current. The electrode/electrolyte interface behaves like a capacitor.

A non-polarizable electrode has no polarization, that is, current flows freely. Its potential does not change from its equilibrium potential upon application of current. The reason for this behavior is that the electrode reaction is extremely fast (has an almost infinite exchange current density). The electrode-electrolyte interface behaves like a resistor.

The classical examples of the two ideal types of electrodes, polarizable and non-polarizable, are the platinum electrodes and the silver/silver chloride, respectively.[2]

The concept of the ideal polarizability has been first introduced by F.O. Koenig in 1934.[1]

References

  1. 1 2 Vladimir Sergeevich Bagot'skiĭ, "Fundamentals Of Electrochemistry",John Wiley & Sons, 2006, p. 178. ISBN 9780471700586
  2. ↑ Neuman, M. R. “Biopotential Electrodes.”, The Biomedical Engineering Handbook: Second Edition, CRC Press LLC, 2000, ISBN 9781420049510 Allen J. Bard, Larry R. Faulkner, "Electrochemical methods; Fundamentals and Applications", John Wiley & Sons, 2001, ISBN 0-471-04372-9
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