in Fuel Cells
How can nanotechnology improve fuel cells?
are used with fuels such as hydrogen or methanol to produce hydrogen ions.
Platinum, which is very expensive, is the catalyst typically used in this
process. Companies are using nanoparticles of platinum to reduce the amount of
platinum needed, or using nanoparticles of other materials to replace platinum
entirely and thereby lower costs.
cells contain membranes that allow
hydrogen ions to
pass through the cell but do not allow other atoms or ions, such as oxygen,
to pass through. Companies are using nanotechnology to create more efficient
membranes; this will allow them to build lighter weight and longer lasting fuel
fuel cells are being developed that can be used to replace batteries in handheld
devices such as PDAs or laptop computers. Most companies working on this type of
fuel cell are using methanol as a fuel and are calling them DMFC's, which stands
for direct methanol fuel cell. DMFC's are designed to last longer than
conventional batteries. In addition, rather than plugging your device into an
electrical outlet and waiting for the battery to recharge, with a DMFC you
simply insert a new cartridge of methanol into the device and you're ready to
cells that can replace batteries in electric cars are also under development.
Hydrogen is the fuel most researchers propose for use in fuel cell powered cars.
In addition to the improvements to catalysts and membranes discussed above, it
is necessary to develop a lightweight and safe hydrogen fuel tank to hold the
fuel and build a network of refueling stations. To build these tanks,
researchers are trying to develop lightweight nanomaterials that will absorb the
hydrogen and only release it when needed. The Department of Energy is estimating
that widespread usage of hydrogen powered cars will not occur until
Researchers at Northwestern University have demonstrated the use of a
Metal-Organic-Framework (MOF) to store gases such as hydrogen or
Researchers at the Technical University of Munich developed a model
to predict the optimum size for platinum nanoparticle catalysis and then
verified that particles one nanometer in diameter and containing approximately 40 platinum atoms showed increased catalytic effectivness.
Researchers at Brookhaven National Lab are reporting the development
of a "nanoplate"
catalyst using platinum and lead that has both a high level of oxygen
reduction and a long lifetime.
Researchers at the University of Copenhagen have demonstrated the
ability to significantly reduce the amount of platinum needed as a
catalyst in fuel cells. The researchers found that the spacing
between platinum nanoparticles affected the catalytic behavior, and that
by controlling the
density of the platinum nanoparticles they could reduce the amount
of platinum needed.
Researchers at Brown University are developing a catalyst that uses
no platinum. The catalyst is made from a sheet of
graphene coated with cobalt
nanoparticles. If this catalyst works out for production use with
fuel cells it should be much less expensive than platinum based
Researchers at Indiana University have demonstrated a
modified emzyme encapsulated by a
protein shell that can function either as a fuel cell catalyst or
as a catalyst to produce hydrogen.
Researchers at Ulsan National Institute of Science and Technology
have demonstrated how to produce
edge-halogenated graphene nanoplatelets
that have good catalytic properties. The researchers prepared
the nanoplatelets by ball-milling graphene flakes in the presence of
chlorine, bromine or iodine. They believe these halogenated
nanoplatelets could be used as a replacement for expensive platinum
catalystic material in fuel cells.
Researchers at Cornell University have developed a
using platinum-cobalt nanoparticles that produces 12 times more
catalytic activity than pure platinum. In order to achieve this
performance the researchers annealed the nanoparticles so they formed a
crystalline lattice which reduced the spacing between platinum atoms on
the surface, increasing their reactivity.
Researchers at the University of Illinois have developed a
proton exchange membrane using a silicon
layer with pores of about 5 nanometers in diameter capped by a layer of porous silica. The silica layer is designed to insure that water stays in the nanopores. The water combines with the acid molecules along the wall of the nanopores to form an acidic solution, providing an easy pathway for hydrogen ions through the membrane. Evaluation of this membrane showed it to have much better conductivity of hydrogen ions (100 times better conductivity was reported) in low humidity conditions than the membrane normally used in fuel cells.
Researchers at Rensselaer Polytechnic Institute have investigated the
storage of hydrogen in graphene (single atom thick carbon sheets). Hydrogen has a high bonding energy to carbon, and the researchers used annealing and plasma treatment to increase this bonding energy. Because graphene is only one atom thick it has the highest surface area exposure of carbon per weight of any material. High hydrogen to carbon bonding energy and high surface area exposure of carbon gives graphene
has a good chance of storing hydrogen. The researchers found that they
could store 14% by weight of hydrogen in graphene.
Researchers at Stony Brook University have demonstrated that gold
nanoparticles can be very effective at using solar energy to generate
hydrogen from water. The key is making the nanoparticles very small.
They found that
nanoparticles containing less than a dozen gold atoms are very
effective photocatalysts for the generation of hydrogen.
Researchers at the SLAC National Accelerator Laboratory have developed a way to use less platinum for the cathode in a fuel cell, which could significantly reduce the cost of fuel cells. They alloyed platinum with copper and then removed the copper from the surface of the film, which caused the platinum atoms to move closer to each other (reducing the lattice space). It turns out that
platinum with reduced lattice spacing is more a more effective catalyst for breaking up oxygen molecules into oxygen ion. The difference is that the reduced spacing changes the electronic structure of the platinum atoms so that the separated oxygen ions more easily released, and allowed to react with the hydrogen ions passing through the proton exchange membrane.
Another way to reduce the use of platinum for catalyst in fuel cell cathodes is being developed by researchers at Brown University. They deposited a one nanometer thick layer of platinum and iron on spherical nanoparticles of palladium. In laboratory scale testing they found that an
catalyst made with these nanoparticles generated 12 times more current
than a catalyst using pure platinum, and lasted ten times longer.
The researchers believe that the improvement is due to a more efficient
transfer of electrons than in standard catalysts.
Increasing catalyst surface area
and efficiency by depositing platinum on porous alumina
Allowing the use of lower purity, and
therefore less expensive, hydrogen with an anode made made of
nanoparticles deposited on titanium oxide.
Replacing platinum catalysts
with less expensive nanomaterials
hydrogen fuel cells to power
nanostructured vanadium oxide in the anode of solid oxide fuel cells.
The structure forms a battery, as well a fuel cell, therefore the cell
can continue to provide electric current after the hydrogen fuel runs
Fuel Cell Resources
Department of Energy
Hydrogen and Fuel Cells Program
Fuel Cell Research Center
Fuel Cell Partnership
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