Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 67: Poster Wednesday: Solid-Liquid Interfaces

O 67.2: Poster

Mittwoch, 3. April 2019, 17:45–20:00, Poster B2

Asymmetric Potential Screening at Electrode/Ionic Liquid Interfaces — Sunghwan Shin, •Francesco Greco, Florian Maier, and Hans-Peter Steinrück — Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany

Ionic liquids (ILs) have received considerable attention as unique candidates to perform electrochemistry due to their larger electrochemical windows and high ion densities. To understand and control an electrochemical reaction in ILs, it is essential to understand the interface between ILs and metal electrodes playing a crucial role in capacitance charging and redox reactions. For ILs, potential screening (PS) at the anode and cathode interface can be dramatically different due to the asymmetric shape of the IL ions and their specific interactions with the charged electrodes. We studied PS effects by use of X-ray photoelectron spectroscopy (XPS) with an in situ two-electrode-cell. The amount of PS at the anode/cathode was determined using XPS binding energy shifts of the IL signals. In the case of symmetric Pt-Pt electrodes, the potential screening at the cathode was smaller than that at the anode for imidazolium-based ILs, which indicates a specific adsorption of imidazolium on platinum. For the Au-Au-setup, weak specific adsorption of imidazolium on gold leads to different PS effects that are related to the size of ions. Supported by the European Research Council (ERC) through an Advanced Investigator Grant to HPS (No. 693398*ILID)