Publication Details (including relevant citation information):
H.L. Abbott, A. Aumer, Y. Lei, S. Asocan, R.J. Meyer, M. Sterrer, S. Shaikhutdinov, and H.-J. Freund, Journal of Physical Chemistry C accepted (2010).
Supported Au-Pd catalysts have been shown to exhibit superior catalytic performances when compared to their monometallic counterparts in a variety of reactions. In addition, the nature of the support often plays a critical role in reactivity. To gain a deeper understanding of the structure-reactivity relationship of the Au-Pd catalysts, here we have employed model systems where monometallic and bimetallic Au-Pd nanoparticles are deposited on well-ordered thin films of reducible and irreducible oxides (i.e., Fe3O4(111), MgO(100), and CeO2(111)). Surface structures of the model systems were characterized by temperature-programmed desorption, sum frequency generation, and infrared reflection absorption spectroscopy of CO as a probe molecule. In agreement with previous studies, the results show segregation of gold to the surface. Density functional theory calculations confirm that Au prefers to be at the edges of AuPd alloy particles under vacuum conditions. Strong similarities between the spectral features observed for metal particles on these oxide substrates suggest that the reducibility of the support does not affect the surface structure.
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