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O: Fachverband Oberflächenphysik

O 42: Solid-Liquid Interfaces: Reactions and Electrochemistry - Theory II

O 42.4: Vortrag

Dienstag, 21. März 2017, 14:45–15:00, WIL B321

Coadsorption of anions and cations on platinum — •Florian Gossenberger and Axel Groß — Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm/Germany

The relevant reaction steps in electrochemistry occur in the region were ion-conduction of the electrolyte merges electron-conduction of the electrode. This area is crucially influenced by the presence or absence of both anions and cations, which are - dependent on the electrode potential - specifically adsorbed on the electrode.

To understand the structure and stability of the adsorbate layer, we have investigated the simultaneous adsorption of different anions (Cl⁻, Br⁻, I⁻, SO₄²⁻/HSO₄⁻) and protons/hydronium on platinum, using density functional theory [1]. The dependence of the adsorption structures on the ionic concentrations in the electrolyte and on electrode potential have been derived using the concept of the computational hydrogen electrode, allowing to derive phase diagrams and Pourbaix diagrams. Thus we have been able to reproduce the experimental finding of the competitive adsorption of hydrogen and halides on Pt(111). With respect to sulphate adsorption our results suggest the need to revisit previously suggest structural models.

[1] F. Gossenberger, T. Roman, A. Groß, Electrochim. Acta 216, 152-159 (2016).