期刊
NATURE MATERIALS
卷 11, 期 2, 页码 155-161出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/NMAT3184
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资金
- Stanford Global Climate Energy Project
- National Science Foundation [DMR-0604004]
- NSF through the Caltech Center for the Science and Engineering of Materials, a Materials Research Science and Engineering Center [DMR-052056]
- Sandia National Laboratories in National Security Science and Engineering
- Sandia Corporation under US Department of Energy [DE-AC04-94AL85000]
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 H-2 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.
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