Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 58: Solid-Liquid Interfaces: Reactions and Electrochemistry II
O 58.1: Vortrag
Mittwoch, 19. März 2025, 10:30–10:45, H4
Step Bunching Instability and its Effects in Electrocatalysis on Platinum Surfaces — •Francesc Valls Mascaró1, Marc T. M. Koper2, and Marcel J. Rost3 — 1Departement of Physical Chemistry, University of Innsbruck — 2Leiden Institute of Chemistry, Leiden University — 3Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University
The atomic-scale surface structure plays a major role in the electrochemical behaviour of a catalyst. The electrocatalytic activity towards many relevant reactions, such as the oxygen reduction reaction on platinum, exhibits a linear dependency with the number of steps until this linear scaling breaks down at high step densities. In this work we show, using Pt(111)-vicinal surfaces and in situ electrochemical scanning tunnelling microscopy, that this anomalous behaviour at high step densities has a structural origin and is attributed to the bunching of closely spaced steps. While Pt(554) presents parallel single steps and terrace widths that correspond to its nominal, expected value, most steps on Pt(553) are bunched. Our findings challenge the common assumption in electrochemistry that all stepped surfaces are composed of homogeneously spaced steps of monoatomic height and can successfully explain the anomalous trends documented in the literature linking step density to both activity and potential of zero total charge [1].
[1] F. Valls Mascaró, M. T. M. Koper, and M. J. Rost, Nat. Catal. 7, 1165 (2024)
Keywords: Electrochemistry; Scanning Tunnelling Microscopy; Stepped Surfaces; Oxygen Reduction Reaction; Potential of Zero Charge