A Thermodynamic Test of the Diffuse Layer Theory and Its Implications on Electrode Kinetics

Ramon González, Fausto Sanz

    Research output: Contribution to journalArticleResearchpeer-review

    20 Citations (Scopus)


    The thermodynamic compatibility of the diffuse layer theory with the chemical potential of ionic species in the solution bulk is introduced. From the electrocapillary equation a compatibility equation, which relates the potential drop across the diffuse layer to the chemical potential of the ionic species in the solution bulk, is deduced for a binary electrolyte. When the Gouy-Chapman (GC) theory is introduced in the compatibility equation, the latter only becomes an identity if the ionic activity is taken as the ionic concentration, as expected. A compatible theory of the diffuse layer which has GC as the limit case at dilute solutions and fulfills the compatibility equation for whatever physical description of the ionic activity coefficients is stated. The significance of the compatible theory is that the electrode reaction rates calculated by means of the electrode kinetic equation with the Frumkin correction using this theory differ from those calculated using GC. In order to test both theories, we have studied the electroreduction of peroxodisulfate at an amalgamated copper rotating disk electrode. The experimental results fit our compatible theory better than GC does.
    Original languageEnglish
    Pages (from-to)169-175
    Issue number2
    Publication statusPublished - 1 Jan 1997


    • Amalgamated copper electrode
    • Diffuse layer
    • Gouy-Chapman theory
    • Peroxodisulfate reduction
    • Thermodynamic compatibility


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