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O: Fachverband Oberflächenphysik

O 60: Solid-Liquid Interfaces III: Reactions and Electrochemistry

O 60.7: Vortrag

Mittwoch, 20. März 2024, 16:45–17:00, MA 042

Oxygen Adsorption at the Electrochemical Metal/Water Interface: Au(111) vs. Pt(111) — •Alexandra M. Dudzinski, Elias Diesen, Karsten Reuter, and Vanessa J. Bukas — Fritz-Haber-Institut der MPG, Berlin

Due to its key role in fuel cell technologies, the oxygen reduction reaction (ORR) has been the subject of extensive studies over the last decades. Dedicated experiments on model single-crystal electrodes have specifically served to establish fundamental trends across transition metal catalysts, e.g., in terms of product selectivity and the effect of applied potential. Such studies revealed that in contrast to Pt-based electrodes, Au shows a distinct preference towards forming hydrogen peroxide (rather than water) with activity that depends strongly on the (absolute) electrode potential. The microscopic origins of this difference are still not well understood and likely lie in details of key elementary reaction steps. Using ab initio molecular dynamics, we recently predicted O₂ adsorption as a critical, potential-dependent step of the ORR on the weak-binding Au(111) surface [1]. In this study, we now draw a direct comparison to the more reactive Pt(111) surface and (i) systematically analyze structural and dynamical properties of the two electrochemical interfaces, as well as (ii) investigate O₂ adsorption as a function of potential. Prominently, we find the more reactive Pt(111) to be predominantly covered by specifically adsorbed solvent species under operating ORR conditions, while chemisorbed O₂ shows an almost negligible response to potential.
[1] Dudzinski et al., ACS Catal. 13, 12074 (2023).

Keywords: electrocatalysis; oxygen reduction reaction; density functional theory; molecular dynamics