An NMR determination of CO diffusion on platinum electrocatalysts

Takeshi Kobayashi, Panakkattu K. Babu, Lajos Gancs, Jong Ho Chung, Eric Oldfield, Andrzej Wieckowski

Research output: Contribution to journalArticlepeer-review

Abstract

We report the first direct measurement of CO diffusion on nanoparticle Pt electrocatalysts at the solid/liquid interface, carried out using 13C nuclear magnetic resonance (NMR) with a spin-labeling pulse sequence. Diffusion parameters were measured in the temperature range of 253-293 K for CO adsorbed on commercial Pt-black under saturation coverage. 2H NMR of the same system indicates that the electrolyte remains in the liquid state at temperatures where the CO diffusion experiments were performed. The CO diffusion parameters follow typical Arrhenius behavior with an activation energy of 6.0 ± 0.4 kcal/mol and a pre-exponential factor of (1.1 ± 0.6)× 10-8 cm2/s. Exchange between different CO populations, driven by a chemical potential gradient, is suggested to be the main mechanism for CO diffusion. The presence of the electrolyte medium considerably slows down the diffusion of CO as compared to that seen on surfaces of bulk metals under UHV conditions. This work opens up a new approach to the study of surface diffusion of adsorbed molecules on nanoparticle electrode catalysts, including the possibility of correlating diffusion parameters to catalytic activity in real world applications of broad general interest.

Original languageEnglish (US)
Pages (from-to)14164-14165
Number of pages2
JournalJournal of the American Chemical Society
Volume127
Issue number41
DOIs
StatePublished - Oct 19 2005

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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