Rate enhancements in structural transformations of Pt-Co and Pt-Ni bimetallic cathode catalysts in polymer electrolyte fuel cells studied by in situ time-resolved X-ray absorption fine structure

Nozomu Ishiguro, Sutasinee Kityakarn, Oki Sekizawa, Tomoya Uruga, Takashi Sasabe, Kensaku Nagasawa, Toshihiko Yokoyama, Mizuki Tada

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

In situ time-resolved X-ray absorption fine structure spectra of Pt/C, Pt3Co/C, and Pt3Ni/C cathode electrocatalysts in membrane electrode assemblies (catalyst loading: 0.5 mgmetal cm-2) were successfully measured every 100 ms for a voltage cycling process between 0.4 and 1.0 V. Systematic analysis of in situ time-resolved X-ray absorption near-edge structure and extended X-ray absorption fine structure spectra in the molecular scale revealed the structural kinetics of the Pt and Pt3M (M = Co, Ni) bimetallic cathode catalysts under polymer electrolyte fuel cell operating conditions, and the rate constants of Pt charging, Pt-O bond formation/breaking, and Pt-Pt bond breaking/re-formation relevant to the fuel cell performances were successfully determined. The addition of the 3d transition metals to Pt reduced the Pt oxidation state and significantly enhanced the reaction rates of Pt discharging, Pt-O bond breaking, and Pt-Pt bond re-forming in the reductive process from 1.0 to 0.4 V.

Original languageEnglish
Pages (from-to)15874-15883
Number of pages10
JournalJournal of Physical Chemistry C
Volume118
Issue number29
DOIs
Publication statusPublished - 2014 Jul 24
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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