Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 90: Metals and semiconductors: Epitaxy and growth

O 90.5: Talk

Friday, March 30, 2012, 11:30–11:45, A 060

Core shell model electrodes: Pt terminated mono- and multilayer CuPt alloys supported on Ru(0001) single crystals. — •Albert K. Engstfeld and R. Jürgen Behm — Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany

Core shell particles consist of a metal A rich shell and a bi- or multialloy core, showing different catalytic activity compared to pure metal particles. An interesting example are Pt enclosed alloy particles containing Cu, Co and Pt, having a much better activity towards oxygen reduction than pure Pt.[1] The effect is mainly attributed to a change of the electronic structure of the shell due to lattice strain within the alloy core.

To study the strain effect we focus on the preparation of mono and bilayer Cu/Pt alloys on Ru(0001) single crystal surfaces under ultra high vacuum conditions, characterized by scanning tunnelling microscopy. From the atom distribution within the alloy we will discuss the dominant factors for alloy formation, in view of the different size of the atoms and difference in their intermetallic bonding. Furthermore, we will elucidate the surface segregation behaviour of Pt in the bilayer alloy during the alloying process.

[1] R. Strivastava, P. Mani, N. Hahn, and P. Strasser, Angewandte Chemie, 46, 8988 (2007)