Identification of defect sites on MgO(100) thin films by decoration with Pd atoms and studying CO adsorption properties

S. Abbet, Elisa Riedo, H. Brune, U. Heiz, A. M. Ferrari, L. Giordano, G. Pacchioni

Research output: Contribution to journalArticle

Abstract

CO adsorption on Pd atoms deposited on MgO(100) thin films has been studied by means of thermal desorption (TDS) and Fourier transform infrared (FTIR) spectroscopies. CO desorbs from the adsorbed Pd atoms at a temperature of about 250 K, which corresponds to a binding energy, Eb, of about 0.7 ∓ 0.1 eV. FTIR spectra suggest that at saturation two different sites for CO adsorption exist on a single Pd atom. The vibrational frequency of the most stable, singly adsorbed CO molecule is 2055 cm-1. Density functional cluster model calculations have been used to model possible defect sites at the MgO surface where the Pd atoms are likely to be adsorbed. CO/Pd complexes located at regular or low-coordinated O anions of the surface exhibit considerably stronger binding energies, Eb = 2-2.5 eV, and larger vibrational shifts than were observed in the experiment. CO/Pd complexes located at oxygen vacancies (F or F+ centers) are characterized by much smaller binding energies, Eb = 0.5 ± 0.2 or 0.7 ± 0.2 eV, which are in agreement with the experimental value. CO/Pd complexes located at the paramagnetic F+ centers show vibrational frequencies in closest agreement with the experimental data. These comparisons therefore suggest that the Pd atoms are mainly adsorbed at oxygen vacancies.

Original languageEnglish (US)
Pages (from-to)6172-6178
Number of pages7
JournalJournal of the American Chemical Society
Volume123
Issue number25
DOIs
StatePublished - Oct 4 2001

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Carbon Monoxide
Adsorption
Thin films
Atoms
Defects
Binding energy
Vibrational spectra
Oxygen vacancies
Thermal desorption
Oxygen
Fourier transform infrared spectroscopy
Fourier transforms
Negative ions
Fourier Analysis
Fourier Transform Infrared Spectroscopy
Infrared radiation
Anions
Molecules
Hot Temperature
Temperature

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Identification of defect sites on MgO(100) thin films by decoration with Pd atoms and studying CO adsorption properties. / Abbet, S.; Riedo, Elisa; Brune, H.; Heiz, U.; Ferrari, A. M.; Giordano, L.; Pacchioni, G.

In: Journal of the American Chemical Society, Vol. 123, No. 25, 04.10.2001, p. 6172-6178.

Research output: Contribution to journalArticle

Abbet, S. ; Riedo, Elisa ; Brune, H. ; Heiz, U. ; Ferrari, A. M. ; Giordano, L. ; Pacchioni, G. / Identification of defect sites on MgO(100) thin films by decoration with Pd atoms and studying CO adsorption properties. In: Journal of the American Chemical Society. 2001 ; Vol. 123, No. 25. pp. 6172-6178.
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