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with an electrophile. For application of these groups in
directed ortho-lithiation see (31).
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23. Materials and methods are available as supporting
material on Science Online.
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in the reaction of Ni(COD)2 and PCy3 with H2 in
the absence of diphenlyl ether under the same
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(methoxynaphthalenes) and alkyl aryl ethers containing
directing groups ortho to the C-O bond (33, 34).
28. No reaction was observed in the absence of Ni(COD)2,
as shown through control experiments on the cleavage of
4-tert-butylbenzyl methyl ether with hydrogen in the
presence of AlMe3 (1 equiv.), SIPr·HCl (0.4 equiv.),
and NaOtBu (2.5 equiv.) in m-xylene at 120°C for
32 hours (23).
29. For example, heterogeneous hydrogenolysis of alkyl
benzyl ethers proceeds selectively in the presence of
diaryl ethers over Pd(OH)2/C (35).
32. M. E. van der Boom, S. Y. Liou, Y. Ben-David,
L. J. W. Shimon, D. Milstein, J. Am. Chem. Soc. 120,
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36. We thank the BP for financial support of this project
through the Energy Biosciences Program and
T. Rauchfuss for helpful discussions. A provisional patent
has been filed on the methods presented herein.
Supporting Online Material
Materials and Methods
Figs. S1 to S3
Tables S1 to S6
15 November 2010; accepted 11 March 2011
for Oxygen Reduction Derived
from Polyaniline, Iron, and Cobalt
Gang Wu,1 Karren L. More,2 Christina M. Johnston,1 Piotr Zelenay1*
The prohibitive cost of platinum for catalyzing the cathodic oxygen reduction reaction (ORR)
has hampered the widespread use of polymer electrolyte fuel cells. We describe a family of
non–precious metal catalysts that approach the performance of platinum-based systems at a
cost sustainable for high-power fuel cell applications, possibly including automotive power. The
approach uses polyaniline as a precursor to a carbon-nitrogen template for high-temperature
synthesis of catalysts incorporating iron and cobalt. The most active materials in the group catalyze
the ORR at potentials within ~60 millivolts of that delivered by state-of-the-art carbon-supported
platinum, combining their high activity with remarkable performance stability for non–precious
metal catalysts (700 hours at a fuel cell voltage of 0.4 volts) as well as excellent four-electron
selectivity (hydrogen peroxide yield <1.0%).
Thanks to the high energy yield and low environmental impact of hydrogen oxida- tion, the polymer electrolyte fuel cell (PEFC)
represents one of the most promising energy
conversion technologies available today. Of the
many possible applications, ranging from sub-watt
remote sensors to residential power generators in
excess of 100 k W, automotive transportation is
especially attractive. PEFCs promise major improvements over gasoline combustion, including
better overall fuel efficiency and reduction in emissions (including CO2). The spectacular progress
in fuel cell technology notwithstanding, a large-
1Materials Physics and Applications Division, Los Alamos National
Laboratory, Los Alamos, NM 87545, USA. 2Materials Science and
Technology Division, Oak Ridge National Laboratory, Oak Ridge,
TN 37831, USA.
*To whom correspondence should be addressed. E-mail:
scale market introduction of fuel cell–powered
vehicles continues to face various challenges, such
as the lack of hydrogen infrastructure and the
technical issues associated with PEFC performance and durability under the operating conditions of an automotive power plant. The high cost
of producing PEFCs represents the most formidable challenge and has driven much of the applied and fundamental fuel cell research in recent
According to the latest cost analysis, the fuel
cell—more precisely, the fuel cell stack—is re-
sponsible for more than 50% of the PEFC pow-
er system cost (1, 2). Although a state-of-the-art
PEFC stack uses several high-priced components,
the catalysts are by far the most expensive con-
stituent, accounting for more than half of the
stack cost. Because catalysts at both the fuel cell
anode and cathode are based on platinum (Pt) or
platinum alloys, their cost is directly linked to the
price of Pt in the volatile and highly monopolized
precious metal market. The precious metal cat-
alyst is the only fuel cell stack component that
will not benefit from economies of scale, and an
increase in the demand for fuel cell power sys-
tems is bound to drive up the already high price
of Pt, about $1830 per troy ounce at present
($2280 per troy ounce at its maximum in March
2008) (3). Thus, PEFCs are in need of efficient,
durable, and inexpensive alternatives to Pt and