Regensburg 2016 – scientific programme
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O: Fachverband Oberflächenphysik
O 82: Structure of Solid/Liquid Interfaces I
O 82.9: Talk
Thursday, March 10, 2016, 12:30–12:45, H6
Potential step experiments on AgxPt1−x/Pt(111) surface alloys - the influence of the upper potential limit on surface structure — •Stephan Beckord, Sylvain Brimaud, and R. Jürgen Behm — Ulm University, Institute of Surface Chemistry and Catalysis, 89069 Ulm
AgxPt1−x/Pt(111) surface alloys exhibit electrochemical and catalytic properties which differ significantly from those of the individual metals. Studies in our institute revealed them as a very promising candidate for the oxygen reduction reaction [1]. To unveil possible restructuring or corrosion processes during the electrocatalytic reaction, which could strongly influence the electrocatalytic characteristics of the surface alloy, we investigated the electrochemical corrosion behavior of structurally well-defined AgxPt1−x surface alloys on Pt(111) with different Ag contents. The surface alloys were prepared under ultrahigh vacuum (UHV) conditions and structurally characterized by STM before and after electrochemical investigation. Electrochemical characterization was performed in a flow cell set up, which also allows measuring the dissolution of surface atoms during corrosion by a collector electrode. Additionally the corroded surfaces were electrochemically characterized by basic cyclic voltammetry (BCV) in supporting electrolyte (0.5 M H2SO4). We demonstrate that the sensitivity of the surface structure towards corrosion depends sensitively on the surface composition. The role of Pt atoms for stabilizing the Ag surface atoms is discussed. [1] S. Beckord, S. Brimaud, R.J. Behm, ORR on Structurally well-defined AgxPt1−x/Pt(111) surface alloys (in preparation)