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Issue 42, 2016
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Warburg's impedance revisited

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The derivation of Warburg's impedance presented in several books and scientific papers is reconsidered. In the past it was obtained by assuming that the total electric current across the sample is just due to the diffusion, and that the external potential applied to the electrode is responsible for an increase of the bulk density of charge described by Nernst's model. We show that these assumptions are not correct, and hence the proposed derivations are questionable. When the electrochemical impedance of a cell of an insulating material where external charges are injected of a given sign is correctly determined, in the high frequency region the real and imaginary parts do not follow the trends predicted by Warburg's impedance. The analysis presented in this paper is relevant to a symmetric cell, in the Nernstian approximation. It can be easily generalized to the case of an asymmetric cell, assuming boundary conditions where the conduction current across the electrodes is proportional to the surface electric field.

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Publication details

The article was received on 20 Jul 2016, accepted on 30 Sep 2016 and first published on 04 Oct 2016

Article type: Paper
DOI: 10.1039/C6CP05049B
Citation: Phys. Chem. Chem. Phys., 2016,18, 29537-29542
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    Warburg's impedance revisited

    G. Barbero, Phys. Chem. Chem. Phys., 2016, 18, 29537
    DOI: 10.1039/C6CP05049B

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