Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 36: Posters: Bio/organic Molecules on Surfaces, Graphene, Solid/liquid interfaces, Metal Substrates, Electronic Structure Theory
O 36.72: Poster
Dienstag, 1. April 2014, 18:30–22:00, P1
Electrocatalytic activity of structurally well defined AgPt/Pt(111) monolayer surface alloys - correlation between structure and reactivity — •Stephan Beckord, Albert K. Engstfeld, Sylvain Brimaud, and R. Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, 89069 Ulm
Bimetallic surface alloys often show an electrochemical and catalytic behavior very different from that of the respective metal components. This is evident, e.g., in the oxygen reduction reaction (ORR), where Pt is known to be the best single metal catalyst, but modification with transition or noble metals, such as Ni, Co, Cu has been found to result in an improved reactivity.[1]
In this work we report first results on the electrochemical and -catalytic properties of well defined AgxPt1−x surface alloys with different amounts of Ag (0% - 100% Ag) on Pt(111). The surface alloys were prepared under ultra high vacuum (UHV) conditions by evaporation of Ag on Pt(111), followed by annealing to 900 K to form a surface alloy. From scanning tunneling microscopy (STM) the atomic distribution in the topmost layer, as well as the abundance of catalytic relevant ensembles (e.g. Pt1Ag2, Pt2Ag1) can be determined. Subsequently the surfaces are characterized in an electrochemical flow cell on their ORR activity in sulfuric acid. Finally structural properties are discussed in comparison with electrochemical activity and theoretical predictions and will be compared to findings for AuxPt1−x/Pt(111).[2]
[1] J. Greeley et al., J.Phys.Chem. 113 (2009) 4932, [2] S, Brimaud et al., J.Electroanal.Chem., 2013, in press.