SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 52: Heterogeneous Catalysis and Surface Dynamics I
O 52.2: Vortrag
Mittwoch, 29. März 2023, 10:45–11:00, TRE Phy
Probing Au(111) Surface Reconstruction by Electrocatalytic Reactions — •Johannes M. Hermann1, Areeg Abdelrahman1, Ludwig A. Kibler1, and Timo Jacob1,2,3 — 1Institute of Electrochemistry, Ulm University, Ulm, Germany. — 2Helmholtz-Institute-Ulm (HIU), Ulm, Germany. — 3Karlsruhe Institute of Technology, Karlsruhe, Germany.
Au(111) is an extensively studied single crystal and its thermodynamically most stable surface is reconstructed under UHV conditions. Besides the thermally reconstructed and the unreconstructed Au(111) surfaces, in addition, there is also a potential-induced reconstruction in electrochemical environments. The phase transition between the reconstructed and unreconstructed Au(111) electrode surfaces has mostly been investigated by means of in situ scanning tunneling microscopy. Kinetic studies are sparse and in the case of potential-induced reconstruction limited to in situ surface X-ray scattering. Since the electrocatalytic hydrogen evolution reaction (HER) on gold electrodes is strongly structure-sensitive, here we show how it can be used to monitor structural changes of the Au(111) surface [1]. The electrocatalytic activity is highest directly after the surface reconstruction had been lifted, and decreases while the potential-induced reconstruction proceeds, following a simple first-order rate law. In contrast to expectations from conventional electrode kinetics, the rate of the reconstruction process decreases with more negative potential, as the reconstructed surface is stabilized by increasing negative excess charge. [1] J.M. Hermann, et al. Electrochim. Acta. 2020, 347 136287.