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O: Fachverband Oberflächenphysik

O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)

O 35.41: Poster

Dienstag, 12. März 2013, 18:15–21:45, Poster B1

Preparation of PtCu core-shell model catalyst electrodes — •Albert K. Engstfeld, Andreas Bensch, Christoph K. Jung, Regine Weiß, and R. Jürgen Behm — Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany

Core shell particles consisting of a metal A rich shell and a bi- or multialloy core show a different catalytic activity compared to pure metal particles. An interesting example are Pt enclosed alloy particles containing Cu, Co and Pt, which have a much better activity towards the electrocatalytic oxygen reduction than pure Pt.

We will describe on the one hand the preparation of PtCu core on Ru(0001) and on the other hand the preparation of a Pt shell on these alloy surfaces, which reflects a model catalysts for core shell particles. The surfaces were investigated by scanning tunneling microscopy under ultra high vacuum conditions. The formation of PtCu monolayer alloys on Ru(0001), is found to be kinetically hindered, due to the strong binding of Pt to the Ru substrate. This limitation can be overcome, however, by careful selection of the experimental conditions (annealing time, deposition sequence ...).

Depositing Pt on Cu sub-monolayer films on Ru(0001), we find a strong tendency for a place exchange between Pt and the Cu upon room temperature deposition of Pt. This allows the fabrication of 2D PtCu model cores with at least 20 % Pt, which can be used as substrate for subsequent Pt deposition. We will discuss the homogeneity of the system after both preparation steps in view of potential use as model catalyst for further electrochemical/-catalytic investigations.