cost and rapid rate of deterioration of pure-platinum catalysts has
stalled the advancement of fuel-cell technology until now. Brown
University chemists and authors in the Journal
of American Chemical Society have
found a particle that lasts longer and outperforms any commercially
available pure-platinum catalyst.
University have replaced pure-platinum catalysts with a
nanoparticle consisting of a five-nanometer palladium core and an
iron-platinum shell. This new particle uses far less platinum
than the former and is much more efficient and long-lasting as far as
the cathode end of fuel-cell reactions go.
the fuel cell's cathode of this new nanoparticle, a chemistry known
as oxygen reduction reaction occurs creating water as it's waste
instead of carbon
dioxide produced by internal combustion systems. Since the
cathode is where 40 percent of a fuel cell's efficiency is depleted,
this is a critical act that could help fuel-cell's become more
competitive with batteries and internal combustion engines.
tests show that the palladium core/iron-platinum shell nanoparticles
"generated 12 times more current than commercially available
pure-platinum catalysts at
the same weight." In addition, the output lasted 10,000 cycles,
which is 10 times longer than commercially available pure-platinum
models that begin to break down after 1,000 cycles.
to Vismadeb Mazumder, a Brown University graduate student and
co-author, the idea was to mold a shell so that it would keep its
shape while requiring the least amount of platinum to make an
efficient reaction. The iron-platinum shell was made by decomposing
iron pentacarbonyl and reducing platinum acetylacetonate, which
resulted in a shell that is only 30 percent platinum. In the future,
these chemists expect to be able to make thinner shells with even
Mazumder and fellow co-author Shouheng Sun, professor of chemistry at
Brown, are working to find why the catalytic abilities of the
iron-platinum shell are increased by the palladium core. They think
the transfer of electrons between the core and shell metals might be
the cause, and both chemists are trying to use a more chemically
active metal than palladium as the core to "confirm the transfer
of of electrons in the core-shell arrangement. and its importance to
the catalysts function." In addition, they created iron-platinum
shells varying from one to three nanometers in width, with
one-nanometer functioning the best.
is a very good demonstration that catalysts with a core and a shell
can be made readily in half-gram quantities in the lab, they're
active and they last," said Mazumder. "The next step is to
scale them up for commercial
use, and we are confident we'll be able to do that."