Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 60: Chemistry at Solid/Liquid Interfaces

O 60.12: Talk

Wednesday, March 9, 2016, 18:00–18:15, S052

Equilibrium coverages of ions on metals electrodes — •Florian Gossenberger, Tanglaw Roman, and Axel Groß — Institute of Theoretical Chemistry, Ulm University, D-89069 Ulm/Germany

Electrocatalytic reactions typically take place close to the surface of the electrode, i.e., in the region of the electrochemical double layer. These reactions might be substantially affect by adsorbates on the electrode which originate from the electrolyte. They can contribute to catalytic steps by directly interacting with the reactants, by changing the work function, or simply by blocking adsorption sites on the surface.

In this study we have addressed the equilibrium coverage of ions on Pt(111) in the presence of electrolytes using density functional theory. By applying the concept of the computational hydrogen electrode, we have derived the stability of structures at the electrode surface at different electrochemical potentials which are a function of electrode potential, pH, ion concentrations and temperature [1].

With this information we are able to draw phase diagrams for several coadsorption systems. Thereby we can address the open question whether synergistic effects are present in coadsorption systems of halides (Cl⁻, Br⁻, I⁻) and hydrogen on Pt(111). Our results indicate that the adsorption of these species is competetive, i.e., that either purely hydrogen-covered or purely halide-covered phases are stable.

[1] F. Gossenberger, T. Roman, A. Groß, Surf. Sci. 631, 17 (2015).