Temperature-dependent structuring of Au-Pt bimetallic nanoclusters on a thin film of Al2O3/NiAl(100)

Meng Fan Luo, Chao Chuan Wang, Chen Sheng Chao, Chiun Yu Ho, Cheng Ting Wang, Won Ru Lin, Yin Chang Lin, Yu Lin Lai, Yao Jane Hsu

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11 Scopus citations

Abstract

Au-Pt bimetallic nanoclusters on a thin film of Al2O 3/NiAl(100) undergo significant structural evolution on variation of the temperature. Au and Pt deposited sequentially from the vapor onto thin-film Al2O3/NiAl(100) at 300 K form preferentially bimetallic nanoclusters (diameter ≦ 6.0 nm and height ≦ 0.8 nm) with both Au and Pt coexisting at the cluster surface, despite the order of metal deposition. These bimetallic clusters are structurally ordered, have a fcc phase and grow with their facets either (111) or (001) parallel to the -Al2O 3(100) surface. Upon annealing the clusters to 400-500 K, the Au atoms inside the clusters migrate toward the surface, resulting in formation of a structure with a Pt core and an Au shell. Annealing the sample to 500-650 K reorients the bimetallic clusters - all clusters have their (001) facets parallel to the oxide surface - and induces oxidation of Pt. Such annealed bimetallic clusters become encapsulated with the aluminium-oxide materials and a few Au remain on the surface.

Original languageEnglish
Pages (from-to)1531-1541
Number of pages11
JournalPhysical Chemistry Chemical Physics
Volume13
Issue number4
DOIs
StatePublished - 28 Jan 2011

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