Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 46: Nanostructures and Clusters

O 46.5: Vortrag

Mittwoch, 13. März 2013, 11:30–11:45, H45

A key to understanding gold nanoalloys: the interplay of fluxionality and electronic structure — •Linn Leppert¹, Rodrigo Q. Albuquerque², Adam S. Foster³, and Stephan Kümmel¹ — ¹Theoretische Physik IV, Universität Bayreuth, 95440 Bayreuth, Germany — ²Institute of Chemistry of São Carlos, University of São Paulo, 13560-970 São Carlos-SP, Brazil — ³Department of Applied Physics, Aalto University School of Science, P.O. Box 11100, FI-00076 Aalto, Finland

The high catalytic activity of Au nanoparticles (NP) is a prime example for the special properties of metal clusters. By alloying, e.g. with Pt, the properties of Au NP can further be significantly improved. Turnover rates in methanol fuel cells and other oxidation reactions are practically relevant examples. However, the fundamental question of why alloying improves the NP properties is still poorly understood. The finding that the high catalytic activity of Au-Pt nanoalloys is observed in a variety of reactions indicates that there is a combination of rather fundamental, basic properties that are not specific to certain chemical environments and that can be optimized by alloying. We show that electronic properties that are relevant for chemical reactivity, e.g. the density of states (DOS) at the Fermi level and the spatial orbital structure, can be associated with Pt. On the other hand we demonstrate that an increasing amount of Au increases the Au-Pt NP fluxionality. Thus, by combining Au and Pt both the DOS and the particle's fluxionality can be adjusted and a catalytically optimal interaction strength between catalyst and reactants be obtained.