Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 23: Solid-Liquid Interfaces II: Electrode Surfaces
O 23.5: Vortrag
Dienstag, 2. April 2019, 11:45–12:00, H5
Influence of steps and atomic ensembles for the CO electro-oxidation — •Jens Klein, Albert K. Engstfeld, Valeria Chesnyak, Sylvain Brimaud, and R. Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm
The rate of electrocatalytic reactions is often highly sensitive to the surface structure of the metal catalysts.[1,2] To improve the performance of catalyst materials it is inevitable to identify active surface sites and to understand the electrocatalytic processes at the surface sites on an atomic scale.
In this work we report on the role of Pt steps and atomic PtRu ensembles in the CO electro-oxidation i) on Pt(111) model electrodes with varying step density and ii) on PtxRu1−x/Ru(0001) surface alloys with varying Pt content, respectively. The model electrodes were prepared and structurally characterized by scanning tunneling microscopy (STM) under ultra-high vacuum (UHV) conditions. The electrocatalytic measurements were performed in an electrochemical flow cell attached to the UHV system. To investigate the role of Pt step sites for the CO electro-oxidation, the steps of the Pt(111) electrodes were passivated for the reaction by condensation of Au. The CO oxidation activity of PtxRu1−x/Ru(0001) surface alloys with different Pt contents was correlated with the abundance of specific PtRu ensembles on the surface. We will discuss the influence and importance of defect sites as well as ensemble sites for the electro-catalytic CO oxidation.
[1] M. T. M. Koper, Nanoscale 3 (2011) 2054. [2] A. K. Engstfeld et al., Angew. Chem. Int. Ed. 53 (2014) 12936.