Automobile exhaust catalysis at the atomic scale: Atom-probe investigations on platinum alloys

P. A J Bagot, A. Cerezo, G. D W Smith, T. Visart De Bocarmé, T. J. Godfrey

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

A dedicated three-dimensional atom-probe has been fitted with an in situ high pressure/temperature reaction cell. This was used for studying the interaction of gases with Pt-alloy surfaces typical of those employed in automotive exhaust catalysis. The reactions of nitric oxide (NO) and oxygen (O2) on Pt and Pt-17.4 at.% Rh FIM specimens were explored, revealing a range of surface restructuring and segregation effects, which depend sensitively on catalyst composition, orientation, temperature and gas chemistry. Specifically, we observed that exposure of Pt-Rh to either NO or O2 at 422-473 K and 10 mbar induced Rh surface segregation uniformly over the surface. However, on raising the temperature to 573 K or higher, the Pt-Rh{111} surface remained Rh-enriched but the Pt-Rh{001} surface became severely Rh-depleted. We attribute this observation to the possible diffusion of Rh species across the specimen apex, indicating that segregation occurs in directions both normal and parallel to the surface in Pt-Rh catalysts. Copyright © 2007 John Wiley & Sons, Ltd.

Original languageEnglish
Pages (from-to)172-177
Number of pages6
JournalSurface and Interface Analysis
Volume39
Issue number2-3
DOIs
Publication statusPublished - Feb 2007

Keywords

  • Atom-probe
  • Heterogeneous catalysis
  • Platinum
  • Rhodium
  • Segregation
  • Surface diffusion

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