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O: Fachverband Oberflächenphysik

O 106: Poster Session VIII: Poster to Mini-Symposium: Electrified solid-liquid interfaces III

O 106.1: Poster

Donnerstag, 4. März 2021, 13:30–15:30, P

Gouy-Chapman and beyond: A new double layer model for Pt — •Katharina Doblhoff-Dier — Leiden University, Leiden, The Netherlands

The Gouy-Chapman-Stern model and its various extensions (e.g., modified to include finite-size effects) are expected to represent the electric double layer structure in dilute electrolytes rather well. Consequently, these models form the basis of many constant-potential methods available in the various electronic structure codes. However, recent experimental results [1,2] show that the double layer capacitance of Pt(111) surfaces, and (to a lesser extent) of Au(111), does not follow the predictions made by these simplistic models. Consequently, we need to rethink the structure of the electric double layer. A reasonable match between theory and experiment can be attained when extending the standard Gouy-Chapman-Stern-like capacitance models by i) the hyperpolarizability caused by water adsorbing at the interface and ii) a weak attractive ion-surface interaction. These little effects strongly alter the potential vs. electric relation of the interface as well as the z-dependence of the near-surface electric field. Inclusion of these effects therefore does not only suggest a renewed picture of the double layer structure, the correct description of these properties is also relevant in order to obtain accurate adsorption energies of polar molecules and reaction barriers from first principle calculations.

[1] K. Ojha, N. Arulmozhi, D. Aranzales, and M.T. M. Koper; Angew. Chem. Int. Ed. 59, 711 (2020)

[2] K. Ojha, K. Doblhoff-Dier, M.T.M. Koper (unpublished)