Mechanism for CO Oxidation and Oscillatory Reactions on Pd Tip and Pd(110) Surfaces: FEM, TPR, XPS Studies
V. V. Gorodetskii1, A. V. Matveev1, A. V. Kalinkin1 and B. E. Nieuwenhuys2
1G. K. Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences,
Pr. Akademika Lavrentyeva 5, Novosibirsk 630090 (Russia), E-mail: gorodetsk@catalysis.nsk.su
2Leiden Institute of Chemistry, P. O. Box 9502, 2300 RA Leiden (The Netherlands)
Страницы: 67-74
Аннотация
Detailed studies of the coadsorption of oxygen and carbon monoxide, hysteresis phenomena and oscillatory reaction of CO oxidation on Pd(110) and Pd tip surfaces have been carried out with the molecular beam (MB), field electron microscope (FEM), temperature programmed reaction (TPR) and X-ray photoelectron spectroscopy (XPS). It has been found that the occurrence of kinetic oscillations over Pd surfaces is associated with periodic formation and depletion of subsurface oxygen (Osub). Transient kinetic experiments show that CO does not react chemically with subsurface oxygen to form CO2 below 300 K. It has been found that CO does react with an atomic Oads/Osub state beginning at temperature ~150 K. Analysis of Pd tip surface with a local resolution of ~20 Å shows the availability of a sharp boundary between the mobile COads and Oads fronts.
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