Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 60: Solid-Liquid Interfaces: Structure, Spectroscopy, Reactions and Electrochemistry

O 60.10: Poster

Dienstag, 21. März 2017, 18:30–20:30, P2-OG2

The AgxPt1−x/Pt(111) surface alloy system as model catalyst for the ORR - Studies on the effect of structure and corrosion on the electrocatalytic activit — •Stephan Beckord, Sylvain Brimaud, and R. Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, 89069 Ulm, Germany

Bimetallic surface alloys often exhibit catalytic and electrochemical properties which significantly differ from those of the respective pure metals. AgPt electrode surfaces were predicted to exceed the activity of Pt on the oxygen reduction reaction [1], where the latter is known to be the best mono metallic catalyst for this reaction. The increased activity of AgPt was also confirmed by experimental studies in our institute. In this work we present results on the effect of restructuring and corrosion of the model electrode surfaces under reaction conditions on the electrocatalytic characteristics and activity of well-defined AgxPt1−x/Pt(111) surface alloys. The surface alloys were prepared and structurally characterized by scanning tunneling microscopy (STM) under ultra high vacuum (UHV) conditions before and after electrochemical investigation. The electrochemical behavior of the model electrodes was studied before and after electrochemical dissolution of Ag atoms in a flow-cell setup by cyclic voltammetry (CV), the activity by measurements on the ORR, respectively. Correlation between structural changes in the corroded surfaces and the oxygen reduction reaction activity are discussed. [1] J. Greeley and J.K. Norskov, J. Phys. Chem. 113 (2009) 4932.

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