SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 96: Solid-Liquid Interfaces III: Reactions and Electrochemistry II
O 96.4: Vortrag
Freitag, 31. März 2023, 11:15–11:30, TRE Phy
Kinetics of the initial step in Pt electrochemical oxidation — Jan Ole Fehrs1, •Timo Fuchs1, Olaf Magnussen1, Chentian Yuan2, David Harrington2, Valentin Briega Martos3, Serhiy Cherevko3, and Jakub Drnec4 — 1Christian-Albrechts Universität zu Kiel — 2University of Victoria — 3Helmholtz Institute Erlangen-Nürnberg for Renewable Energy — 4European Synchrotron Radiation Facility
A key event in electrochemical metal oxidation is extraction of a metal atom from its lattice site to a location in a growing oxide. The direct observation of this fundamental step is difficult for base metals that actively corrode, because of the difficulty of producing clean surfaces and the speed of the oxidation. However, use of noble metals allows preparation of clean surfaces that are well-defined on the atomic scale, and for which in situ methods can directly observe this extraction. Here we show by fast simultaneous electrochemical and high-energy surface X-ray diffraction measurements, performed at the ID31 beamline of the European Synchrotron Radiation Facility with a photon energy of 70 keV, that the initial extraction of Pt atoms from Pt(111) is a fast, potential-driven process whereas charge transfer for the related formation of adsorbed oxygen occurs on a slower time scale. Electrochemical oxidation is therefore inherently different from gas-phase thermal oxidation, where the extraction must be driven by the chemisorption of oxygen species on the surface.
The work was funded by the Deutsche Forschungsgemeinschaft via grant 418603497 and the BMBF via project 05K19FK3.