Mechanism of CO oxidation reaction on O-covered Pd(111) surfaces studied with fast x-ray photoelectron spectroscopy: Change of reaction path accompanying phase transition of O domains

Ikuyo Nakai, Hiroshi Kondoh, Toru Shimada, Andrea Resta, Jesper N. Andersen, Toshiaki Ohta

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We studied the mechanism of CO oxidation on O-precovered Pd(111) surfaces by means of fast x-ray photoelectron spectroscopy (XPS). The oxygen overlayer is compressed upon CO coadsorption from a p (2×2) structure into a (3×3) R30° structure and then into a p (2×1) structure with increasing CO coverage. These three O phases exhibit distinctly different reactivities. (1) The p (2×2) phase does not react with CO unless the surface temperature is sufficiently high (<290 K). (2) In the (3×3) R30° phase, the reaction occurs exclusively at island peripheries. CO molecules in a high-density phase formed under CO exposure react with oxygen atoms, leading to quite a small apparent activation energy. (3) The reaction proceeds uniformly over the islands in the p (2×1) phase.

Original languageEnglish
Article number224712
JournalJournal of Chemical Physics
Issue number22
Publication statusPublished - 2006 Jun 14


ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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