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Summary: Agglomeration, support effects, and CO adsorption
on Au/TiO2(110) prepared by ion beam deposition
Sungsik Lee, Chaoyang Fan, Tianpin Wu, Scott L. Anderson *
Department of Chemistry, University of Utah, 315 S. 1400 E. RM Dock, Salt Lake City, UT 84112-0850, United States
Received 8 October 2004; accepted for publication 6 January 2005
Available online 22 January 2005
Abstract
The agglomeration behavior of 0.05 ML of Au deposited as Au+
at 1 eV impact energy on rutile TiO2(110) was
investigated by a combination of ion scattering, X-ray photoelectron spectroscopy (XPS), CO adsorption, and CO tem-
perature-programmed desorption (TPD). Samples were studied over the temperature range between 115 K and 800 K,
and on both near-stoichiometric UHV-annealed TiO2, and TiO2 with a high density of oxygen vacancies created by He+
bombardment. At low temperatures, Au is atomically dispersed, shifting into complexes with oxygen vacancies for
Tanneal around room temperature, and finally agglomerating into small clusters for Tanneal P 450 K. CO adsorbed
on dispersed atoms results in nearly 1 eV shift in the Au4f binding energy to higher energy, and CO desorption peaking
at 280 K. CO adsorbs more weakly on Auvacancy complexes and on Au in clusters, as indicated by both TPD and
XPS. Comparisons with experiments depositing thermal Au, and implications for size-selected CO oxidation on
Aun/TiO2 are discussed.
Ó 2005 Elsevier B.V. All rights reserved.
Keywords: Sintering; Ion deposition; CO adsorption
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