Microscopic surface structures and ORR activities for vacuum-deposited Pt/Ni/Pt(1 1 1) and Pt/Ni/Pt(1 1 0) sandwich structures

N. Todoroki, T. Dasai, Y. Asakimori, T. Wadayama

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Pt0.3-0.6nm/Ni0.3-0.6nm/Pt(1 1 1) and Pt 0.3-0.6nm/Ni0.3-0.6nm/Pt(1 1 0) atomic sandwich structures were prepared through alternating vacuum depositions of Ni followed by Pt onto clean Pt(1 1 1) and (1 1 0) substrates at room temperature under ultra-high-vacuum (UHV) conditions. After the samples were transferred from UHV to a 1-atm N2 atmosphere, their oxygen reduction reaction (ORR) activities were evaluated in O2-saturated 0.1 M HClO4 at 0.9 V vs. reversible hydrogen electrode. Pt0.6nm/Ni 0.6nm/Pt(1 1 1) and Pt0.6nm/Ni0.6nm/Pt(1 1 0) were most active among the respective Pt/Ni/Pt(1 1 1) and Pt/Ni/Pt(1 1 0) sandwich series: the activities of the former and latter sandwich structures were approximately five- and threefold greater than those of the corresponding clean Pt(1 1 1) and (1 1 0) substrate surfaces. Scanning tunneling microscopy images of the as-prepared Pt0.6nm/Ni0.6nm/Pt(1 1 1) and Pt0.6nm/Ni0.6nm/Pt(1 1 0) surfaces revealed three-dimensionally grown hexagonal-shaped small domains of Pt(1 1 1) (approximately 2 nm in size) and parallelogram-shape (1 1 0) terrace islands oriented along 〈1 1 0〉, respectively. The results indicate that not only the atomic arrangements of the topmost Pt layers but also the nanoscale morphologies of Pt-Ni in the surface vicinities determine the enhancement of the ORR activity of Pt-M alloy catalysts.

Original languageEnglish
Pages (from-to)15-20
Number of pages6
JournalJournal of Electroanalytical Chemistry
Volume724
DOIs
Publication statusPublished - 2014 Jun 15

Keywords

  • Low-energy electron diffraction
  • Molecular beam epitaxy
  • Oxygen reduction reaction
  • Platinum-based alloys
  • Polymer electrolyte membrane fuel cell
  • Scanning tunneling microscopy

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry

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