Pt Skin Versus Pt Skeleton Structures of Pt3Sc as Electrocatalysts for Oxygen Reduction

Tobias Peter Johansson, Elisabeth Therese Ulrikkeholm, Patricia Hernandez-Fernandez, Paolo Malacrida, H. A. Hansen, A. S. Bandarenka, J. K. Nørskov, Jan Rossmeisl, Ifan Stephens, Ib Chorkendorff

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

In order for low temperature polymer electrolyte membrane fuel cells to become economically viable Pt catalyst loading must be significantly reduced. The cathode of the polymer electrolyte membrane fuel cell, where oxygen reduction takes place, is responsible for the main activity loss. The development of new materials for this reaction is essential in order to increase the overall effeciency of the fuel cell. Herein, we study the effect of ultra high vacuum annealing on the structure and activity of polycrystalline Pt3Sc. Upon annealing in ultra high vacuum a Pt overlayer is formed on the polycrystalline Pt3Sc. The reactivity of the overlayer is probed by temperature programmed desorption of CO. The onset of CO desorption is around 130 K lower on UHV annealed Pt3Sc than on Pt(111) and the temperature of the desorption peak maximum at saturation was similar to 50 K lower on UHV annealed Pt3Sc, relative to Pt(111), consistent with the CO adsorption energies calculated using density functional theory calculations. Exposing the annealed Pt3Sc sample to 200 mbar O2 at room temperature results in similar to 14 % Sc oxide as measured by X-ray photoelectron spectroscopy. Electrochemical testing of the oxygen reduction reaction shows the same activity as sputter cleaned Pt3Sc.
Original languageEnglish
JournalTopics in catalysis
Volume57
Issue number1-4
Pages (from-to)245-254
Number of pages10
ISSN1022-5528
DOIs
Publication statusPublished - 2014

Keywords

  • Carbon monoxide
  • Temperature programmed desorption
  • Platinum
  • Scandium
  • Oxygen reduction reaction
  • Ion scattering spectroscopy
  • Angle resolved X-ray photoelectron spectroscopy

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