Effects of potassium on the chemisorption of CO on the Mo2C/Mo(100) surface

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Abstract

The interaction of CO with K-free and K-covered Mo2C/Mo(100) surfaces has been investigated by HREELS, AES, and TPD. CO adsorbed molecularly on the clean Mo2C/Mo(100) surface at 140 K. A part of the adsorbed CO desorbed from the saturated adlayer with Tp = 330 K, which was accompanied by dissociation of the molecule at 300-350 K. The C and O adatoms formed recombined at higher temperatures, giving a CO desorption peak at 960 K. Preadsorbed potassium at intermediate coverages (ΘK = 0.5-0.8 ML) led to a considerable weakening of the C-O bond even at 140 K, as evidenced by the HREELS feature at 1320-1375 cm-1. The appearance of this loss suggested a short-range interaction, while the development of losses at 1670-1685 and 1860 cm-1 is attributed to long-range interaction in the coadsorbed layer. Potassium adatoms decreased the amount of CO desorbed and converted it into a more reactive form, which-instead of desorption-underwent dissociation at 350-550 K. The recombinative desorption of CO occurred at 970 K; its amount was 3 times higher than that measured for K-free Mo2C. Potassium was stabilized in the adsorbed layer mainly by O adatoms arising from the decomposition of CO.

Original languageEnglish
Pages (from-to)4337-4342
Number of pages6
JournalJournal of Physical Chemistry B
Volume105
Issue number19
DOIs
Publication statusPublished - May 17 2001

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ASJC Scopus subject areas

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

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