Surface structure of Pd3Fe(111) and effects of oxygen adsorption

Xiaofang Yang, Lindsey A. Welch, Jie Fu, Bruce E. Koel

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Pd-Fe alloys have attracted attention in PEM fuel cell research because they were found to be comparable to Pt electrocatalysts in oxygen reduction reaction (ORR) kinetics at the cathode. In this study, the surface morphology of a Pd3Fe(111) single-crystal sample and oxygen reaction on the surface were investigated by low energy electron diffraction (LEED), low energy ion scattering (LEIS), x-ray photoelectron spectroscopy (XPS), and scanning tunneling microscopy (STM) under ultra-high vacuum (UHV) conditions. Strong segregation of Pd atoms was observed after annealing in UHV. Particularly, Pd single adatoms and dimers were found on the surface after high temperature annealing, which differs from most other well-studied binary alloy systems. Low free energy of Pd, strain relaxation, and interaction between Pd and Fe, are potentially responsible for the formation of this unusual surface. Adsorption of oxygen reversed the segregation trend and oxidized surface Fe. Ordered surface phases were observed after oxygen exposures at elevated temperatures. The reducing activity of Fe atoms in the alloy inhibited Pd oxidation, and weakened Pd-O interactions on Pd3Fe(111) are consistent with enhanced ORR kinetics.

Original languageEnglish (US)
Title of host publicationCatalytic Materials for Energy, Green Processes and Nanotechnology
Pages89-94
Number of pages6
StatePublished - Sep 3 2010
Externally publishedYes
Event2009 MRS Fall Meeting - Boston, MA, United States
Duration: Nov 30 2009Dec 3 2009

Publication series

NameMaterials Research Society Symposium Proceedings
Volume1217
ISSN (Print)0272-9172

Other

Other2009 MRS Fall Meeting
CountryUnited States
CityBoston, MA
Period11/30/0912/3/09

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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  • Cite this

    Yang, X., Welch, L. A., Fu, J., & Koel, B. E. (2010). Surface structure of Pd3Fe(111) and effects of oxygen adsorption. In Catalytic Materials for Energy, Green Processes and Nanotechnology (pp. 89-94). (Materials Research Society Symposium Proceedings; Vol. 1217).