High electrochemical activity of the oxide phase in model ceria-Pt and ceria-Ni composite anodes

William C. Chueh*, Yong Hao, Woochul Jung, Sossina M. Haile

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

232 Scopus citations

Abstract

Fuel cells, and in particular solid-oxide fuel cells (SOFCs), enable high-efficiency conversion of chemical fuels into useful electrical energy and, as such, are expected to play a major role in a sustainable-energy future. A key step in the fuel-cell energy-conversion process is the electro-oxidation of the fuel at the anode. There has been increasing evidence in recent years that the presence of CeO2-based oxides (ceria) in the anodes of SOFCs with oxygen-ion-conducting electrolytes significantly lowers the activation overpotential for hydrogen oxidation. Most of these studies, however, employ porous, composite electrode structures with ill-defined geometry and uncontrolled interfacial properties. Accordingly, the means by which electrocatalysis is enhanced has remained unclear. Here we demonstrate unambiguously, through the use of ceria-metal structures with well-defined geometries and interfaces, that the near-equilibrium H2 oxidation reaction pathway is dominated by electrocatalysis at the oxide/gas interface with minimal contributions from the oxide/metal/gas triple-phase boundaries, even for structures with reaction-site densities approaching those of commercial SOFCs. This insight points towards ceria nanostructuring as a route to enhanced activity, rather than the traditional paradigm of metal-catalyst nanostructuring.

Original languageEnglish (US)
Pages (from-to)155-161
Number of pages7
JournalNature materials
Volume11
Issue number2
DOIs
StatePublished - Feb 2012

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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