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O: Fachverband Oberflächenphysik

O 64: Focussed Session: Solid-liquid Interfaces I

O 64.2: Talk

Thursday, March 14, 2013, 11:00–11:15, H31

Capacity of Electrochemical Interfaces — •Manuel Landstorfer and Wolfgang Dreyer — Weierstrass Institute for Applied Analysis and Stochastics (WIAS)

The differential capacity C = d q_M / d U, where q_M is the metal (surface) charge and U the applied potential difference between the bulk metal and the bulk electrolyte, of an electrode/electrolyte interface is unique tool to charactarize and investigate combinations of various electrode and electrolyte materials. Classical thermodynamic and continuum mechanical descriptions of the electrode/electrolyte interface only treat the electrolyte environment (in terms of Poisson-Boltzmann-equations and its generalizations) in the derivation of an explicit funcion C=C(U) [3,4]. In contrast, we will model the interface as electrode domain Ω_M and an electrolyte domain Ω_E which share a common singular surface Σ. Based on free energy formulations for the electrolytic solution and the singular surface, as well as contact conditions for the chemical potentials, we derive explicit functions C=C(U) for various types of interfaces:

• metal - dilute electrolyte - no adsorption
• metal - strong electrolyte/ionic liquid - no adsorption
• metal - electrolyte - various adsorption models

Our results are compared to experimental data which allows for a determination of model parameters in our free energy formulation.