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

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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(2x2) structure into a (root 3x root 3)R30 degrees structure and then into a p(2x1) structure with increasing CO coverage. These three O phases exhibit distinctly different reactivities. (1) The p(2x2) phase does not react with CO unless the surface temperature is sufficiently high (< 290 K). (2) In the (root 3x root 3)R30 degrees 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(2x1) phase.


  • I Nakai
  • H Kondoh
  • T Shimada
  • Andrea Resta
  • Jesper N Andersen
  • T Ohta
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Atom and Molecular Physics and Optics
Original languageEnglish
Article number224712
JournalJournal of Chemical Physics
Issue number22
Publication statusPublished - 2006
Publication categoryResearch