In situ transient FTIR and XANES studies of the evolution of surface species in CO oxidation on Au/TiO2

Juan D. Henao, Tiziana Caputo, Jeff H. Yang, Mayfair C. Kung, Harold H. Kung

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Abstract

The adsorption of CO and its reaction with oxygen were investigated using a combination of in situ Fourier transform infrared spectroscopy, step response measurements in a microreactor, 18O isotopic labeling, and X-ray absorption near edge structure spectroscopy. An as-prepared sample in which Au is present as a surface oxyhydroxy complex does not adsorb CO. On an activated sample in which only metallic Au is detected, 0.18 ± 0.03 mol CO/(mol Au) are adsorbed on Au at -60°C, which shows an IR band at 2090 cm -1. When oxygen is present in the gas phase, this species reacts with a turnover rate of 1.4 ± 0.2 mol CO(mol Au min)-1, which is close to the steady-state turnover rate. In contrast, there is a very small quantity of adsorbed oxygen on Au. A small IR peak at,1242 cm-1 appears when an activated sample is exposed to CO. It reacts rapidly with oxygen and is shifted to 1236 cm-1 if 18O is used. It is assigned to the possible intermediate hydroxycarbonyl.

Original languageEnglish
Pages (from-to)8689-8700
Number of pages12
JournalJournal of Physical Chemistry B
Volume110
Issue number17
DOIs
Publication statusPublished - May 4 2006

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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