195Pt NMR of platinum electrocatalysts: Friedel-Heine invariance and correlations between platinum Knight shifts, healing length, and adsorbate electronegativity

Y. Y. Tong, C. Rice, A. Wieckowski, E. Oldfield

Research output: Contribution to journalArticle

Abstract

The influence of a series of different ligands (H, O, S, CN-, CO, and Ru), electrochemically adsorbed onto carbon-supported nanoscale Pt particles, has been investigated by 195Pt NMR, in an electrochemical environment. The NMR Knight shifts from atoms in the interior of the particles are invariant to surface ligand adsorption, as expected by the Friedel-Heine invariance theorem. However, the shifts of the surface and subsurface atoms vary over a ~11000 ppm range for the adsorbates investigated. The Knight shifts of the surface and subsurface platinum atoms, obtained by using an NMR layer-model simulation, linearly map the electronegativity of the adsorbate. These observations permit the derivation of a correlation between the 'healing length' of the Pt metal, a parameter indicating how fast the bulk metal properties are recovered when moving in from the surface, and the electronegativity of the adsorbate, providing a new probe of electrocatalyst and heterogeneous catalyst surface electronic structure.

Original languageEnglish (US)
Pages (from-to)11921-11924
Number of pages4
JournalJournal of the American Chemical Society
Volume122
Issue number48
DOIs
StatePublished - Dec 6 2000

ASJC Scopus subject areas

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

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