Thermodynamic analysis of (bi)sulphate adsorption on a Pt(1 1 1) electrode as a function of pH

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Authors

Colleges, School and Institutes

External organisations

  • Instituto de Electroquímica
  • Universidad de Alicante

Abstract

A complete thermodynamic study of (bi)sulphate adsorption on Pt(1 1 1) electrodes from solutions at four different pHs (pH 0.43, 2.1, 3.1 and 4.1) is reported. The effect of pH on the sum of the Gibbs excesses of sulphate and bisulphate species, standard Gibbs energies of adsorption and formal partial charge numbers is analyzed. The results provide relevant information on the nature of species involved in the different voltammetric features. The experiments at pH 0.43 were performed in a higher base electrolyte concentration (0.5 M), that allows the study of (bi)sulphate adsorption in a broader range of concentrations. Under these conditions, two adsorption steps are clearly defined, associated to two different voltammetric features, between 0.30 and 0.60 V and between 0.65 and 0.90 V (standard hydrogen scale, SHE). Once the pH is increased, a marked decrease in absolute value of the (bi)sulphate adsorption Gibbs energy is observed, concomitant with an increasing amount of OH co-adsorption.

Details

Original languageEnglish
Pages (from-to)6793-6806
Number of pages14
JournalElectrochimica Acta
Volume53
Issue number23
Publication statusPublished - 1 Oct 2008

Keywords

  • Formal partial charge numbers, Gibbs thermodynamics of a Pt electrode, Platinum single-crystal electrodes, Pt(1 1 1), Sulphate and bisulphate adsorption on Pt