Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 10: Solid-liquid Interfaces I
O 10.2: Vortrag
Montag, 31. März 2014, 10:45–11:00, WIL A317
Structural degradation of PtRu model electrodes during CO electrooxidation and its influence on the reaction characteristics — •Albert K. Engstfeld, Jens Klein, Sylvain Brimaud, and R. Jürgen Behm — Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany
The stability of an (electro-)catalyst under reaction conditions is important for the proper understanding of the underlying (electro-) catalytic processes. In this work we present the structural modifications of a PtRu model electrode during the electrooxidation of CO and the resulting changes in the electrocatalytic behavior.
The electrodes are prepared by deposition of Pt (≤ 1 ML) on Ru(0001) under ultra high vacuum (UHV) conditions, leading to Pt monolayer islands with different sizes and densities. Subsequent to the structural characterization by scanning tunneling microscopy (STM), the samples are transferred to a pre-chamber equipped with an electrochemical laminar flow cell. The electrochemical/-catalytic properties of the PtRu electrodes were characterized by base cyclic voltammetry in 0.5 M H2SO4 (potential range of 0 V to 0.9 V or 1.25 V) and by evaluating their activity for CO bulk electrooxidation. Subsequently, the samples were transferred back to the UHV to study modifications of the electrode surface structure by STM. After exposure to higher potentials the surface shows pronounced modifications of the Ru(0001) surface and small Pt islands, which influences the CO oxidation in a distinct way. Correlations between electrode structure / structure modification and reactivity will be discussed.