Regensburg 2022 – scientific programme
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O: Fachverband Oberflächenphysik
O 8: Solid-Liquid Interfaces 1: Reactions and Electrochemistry
O 8.3: Talk
Monday, September 5, 2022, 11:15–11:30, S054
Enhanced Field Effects at Protruding Defect Sites in Electrochemistry? – A Theoretical Evaluation — •Simeon D. Beinlich1,2, Nicolas G. Hörmann1, and Karsten Reuter1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany — 2Technical University of Munich, Munich, Germany
Does electrochemistry at protruding surfaces sites differ significantly from that at ideal low-index surfaces? Intuitively, classical electrostatics suggest a local field enhancement at protruding sites. In this case, a dipole-field-like picture would suggest a pronounced potential-dependence of adsorption energies at such sites.
Here, we evaluate these dependencies for various adsorbates on vicinal Pt(111) surfaces using first-principles calculations in combination with a fully grand canonical approach [1]. Our results show an enhancement of the local electric field at pristine surfaces. However, it is lifted upon adsorption and hence does not cause the anticipated stronger field-effects. Nevertheless, we observe dramatic variations in the potential-dependence which can be rationalized from the differences in surface dipoles that form upon adsorption. These correlate with site coordination showing a consistent trend across adsorbates and adsorption sites.
We rationalize these findings and discuss how the adsorption behavior changes on defect-rich, undercoordinated surfaces in an electrochemical environment.
[1] S.D. Beinlich et al., ACS Catal. 12 6143–6148 (2022)