STM studies of oxygen-induced reconstruction on a Pt-Rh(1007) alloy surface

Yuji Matsumoto, Yasutoshi Aibara, Kozo Mukai, Kuniko Moriwaki, Yuji Okawa, B. E. Nieuwenhuys, Ken Ichi Tanaka

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

Oxygen-induced reconstruction of a Pt-Rh(100) alloy surface was studied by scanning tunneling microscopy (STM). When a clean Pt-enriched Pt-Rh(100) surface was exposed to O2 at more than 600 K, oxygen-induced reconstruction took place with segregation of Rh atoms to the surface. Depending on the coverage of oxygen, two types of reconstruction on the Pt-Rh(100) alloy surface are induced. A p(3 × 1)-O structure appeared at relatively low oxygen coverage, and the TPD spectrum of the p(3 × 1)-O surface gave a desorption peak of O2 at ca. 930 K. The p(3 × 1)-O structure showed several different STM images depending on the tip condition, from which we could distinguish the two component metals, Rh-O rows and Pt rows. Based on this, a model structure was deduced. At a high oxygen coverage, more Rh atoms were segregated to the surface and the STM image suggests a c(2 × 20)-O structure. The c(2 × 20)-O surface changed into the p(3 × 1)-O by heating with the concomitant desorption of O2 at ca. 830 K. The STM images for this c(2 × 20)-O surface is analogous to the arrangement of Rh atoms on the top layer of a Rh(111) hexagonal lattice. Due to the lattice mismatch between the quasi-Rh(111) overlayer and Pt-Rh(100) substrate, a moire pattern with 20 times periodicity along the 〈011〉 directions was observed. Both the p(3 × 1)-O and c(2 × 20)-O surfaces are easily reduced by H2 even at room temperature.

Original languageEnglish
Pages (from-to)32-37
Number of pages6
JournalSurface Science
Volume377-379
DOIs
Publication statusPublished - 1997 Apr 20
Externally publishedYes

Keywords

  • Alloys
  • Auger electron diffraction
  • Auger electron spectroscopy
  • Catalysis
  • Low energy electron diffraction (LEED)
  • Low index single crystal surfaces
  • Oxygen
  • Platinum
  • Rhodium
  • Scanning tunneling microscopy
  • Surface chemical reaction

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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