SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 96: Solid-Liquid Interfaces III: Reactions and Electrochemistry II

O 96.10: Vortrag

Freitag, 31. März 2023, 12:45–13:00, TRE Phy

Parameters Determining Electrode Modification by High Voltage Electrolysis — •Lukas Forschner, Evelyn Artmann, Timo Jacob, and Albert K. Engstfeld — Institute of Electrochemistry, Ulm University, Ulm, Germany

Applying a sufficiently high voltage between two gas-evolving electrodes of different sizes in an aqueous electrolyte can lead to transition from normal electrolysis (NE) to Contact Glow Discharge Electrolysis (CGDE). Due to Joule heating, the electrolyte temperature increases significantly until enough solvent evaporates to form a stable gas sheath around the smaller electrode in which a plasma is ignited. Both in the NE and the CGDE region, the electrode surface can be altered significantly, e.g., by the formation of a Au oxide film[1] or nanoparticles.[2]

During high voltage electrolysis, there are several factors which could influence the restructuring of an electrode surface. First, to disentangle these processes, we measured the distribution of the electric potential in the electrolyte during NE using reversible hydrogen reference electrodes.[3] We found, supported by a COMSOL^® model, that the potential distribution mainly depends on the electrolyte conductivity and the cell geometry. Furthermore, we show that the amount of Au oxide formed on a Au electrode during NE is more closely correlated to the current (density) than the voltage (usually provided in the literature).

[1] Artmann et al., ChemPhysChem 22 (2021) 2429. [2] Allagui et al., Electrochim. Acta 93 (2013) 137. [3] Forschner et al., (2022, submitted).