In situ X-ray probing reveals fingerprints of surface platinum oxide

Phys Chem Chem Phys. 2011 Jan 7;13(1):262-6. doi: 10.1039/c0cp01434f. Epub 2010 Nov 9.


In situ X-ray absorption spectroscopy (XAS) at the Pt L(3) edge is a useful probe for Pt-O interactions at polymer electrolyte membrane fuel cell (PEMFC) cathodes. We show that XAS using the high energy resolution fluorescence detection (HERFD) mode, applied to a well-defined monolayer Pt/Rh(111) sample where the bulk penetrating hard X-rays probe only surface Pt atoms, provides a unique sensitivity to structure and chemical bonding at the Pt-electrolyte interface. Ab initio multiple-scattering calculations using the FEFF code and complementary extended X-ray absorption fine structure (EXAFS) results indicate that the commonly observed large increase of the white-line at high electrochemical potentials on PEMFC cathodes originates from platinum oxide formation, whereas previously proposed chemisorbed oxygen-containing species merely give rise to subtle spectral changes.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Electrochemistry
  • Oxides / chemistry*
  • Oxygen / chemistry
  • Platinum / chemistry*
  • Spectrum Analysis
  • Surface Properties
  • X-Rays


  • Oxides
  • platinum oxide
  • Platinum
  • Oxygen