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Agglomeration, support effects, and CO adsorption on Au/TiO2(110) prepared by ion beam deposition

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
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 Au≠vacancy 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.
” 2005 Elsevier B.V. All rights reserved.
Keywords: Sintering; Ion deposition; CO adsorption


Source: Anderson, Scott L. - Department of Chemistry, University of Utah


Collections: Energy Storage, Conversion and Utilization; Materials Science; Chemistry