Formation of Pd monomers and dimers on a single-crystal Pd 3Fe(111) surface

Xiaofang Yang, Jun Hu, Ruqian Wu, Bruce E. Koel

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Surface reconstruction of binary alloys is important in heterogeneous catalysis because it modifies both surface composition and structure and thus affects the catalytic activity and selectivity. We report here on segregation and surface morphology at a Pd3Fe(111) single-crystal model catalyst investigated by low-energy ion scattering (LEIS) and scanning tunneling microscopy (STM). Annealing in vacuum causes Pd segregation, and STM reveals a complex surface structure with 0.17 monolayers of Pd monomer and dimer adatoms on top of the outermost alloy layer. This result is explained by density functional theory (DFT) calculations, which reveal that the contribution from vibrational free energy causes Pd atoms to detach from step edges at high temperature (>1200 K) and then become trapped at room temperature at Fe defect sites due to a large diffusion barrier. This adlayer structure differs from surface structures observed for other binary alloy systems and is likely to offer new opportunities for manipulating catalytic properties of bimetallic alloys.

Original languageEnglish (US)
Pages (from-to)2493-2497
Number of pages5
JournalJournal of Physical Chemistry Letters
Volume1
Issue number16
DOIs
StatePublished - Aug 19 2010

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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