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Direct-formic acid fuel cells or DFAFCs are a subcategory of
proton-exchange fuel cells where, the fuel, formic acid, is
not reformed, but fed directly to the fuel cell. Their
applications include small, portable electronics such as phones
and laptop computers.
formic acid is a small
organic molecule fed directly into the fuel cell, removing
the need for complicated catalytic reforming. Storage of formic
acid is much easier and safer than that of
hydrogen because it does not need to be done at high
pressures and (or) low temperatures, as formic acid is a liquid
at ambient temperature.
There are two important advantages that formic acid possesses
over methanol for use in the fuel cell. First, formic acid does
not cross over the polymer membrane, so its efficiency can be
higher than that of methanol. Second, formic acid does not cause
blindness as does methanol, making it a somewhat safer fuel in
case of leakage.
DFAFCs convert formic acid and
carbon dioxide and
to produce energy. Formic acid oxiation occurs at the
on a catalyst layer. Carbon dioxide is formed and
protons (H+) are passed through the polymer
membrane to react with oxygen on a catalyst layer located at the
cathode. Electrons are passed through an external circuit
from anode to cathode to provide power to an external device.
Anode: HCOOH → CO2 + 2 H+ + 2 e-
Cathode: 1/2 O2 + 2 H+ + 2 e-
Net reaction: HCOOH + 1/2 O2 → CO2
During previous investigations, researchers dismissed formic
acid as a practical fuel because of the high
overvoltage shown by experiments: this meant the reaction
appeared to be too difficult to be practical.
However, in recent years, other researchers (in particular
Richard Masel's group at the
University of Illinois at Urbana-Champaign) found that the
reason for the low performance was the usage of
platinum as a
catalyst, as it is common in most other types of fuel cells:
palladium instead, they claim to have obtained better
performance than equivalent
direct methanol fuel cells.
Tekion holds the exclusive license to formic-acid fuel cell
technology from the University of Illinois at Urbana-Champaign.
The company now is focusing on developing a miniature hybrid
battery/fuel-cell unit called the
Formira Power Pack and hopes to introduce the packs in the
fourth quarter of 2007. The Power Packs rely on the fuel cell,
instead of a conventional electrical source like a wall outlet,
to recharge the batteries. When the fuel is exhausted, users
simply replace the empty fuel cartridge with a fresh one.
Because of the high power density of the fuel cell, it should
provide about double the time between charges. This technology
is expected to only cost about 10-15% more than traditional
batteries, and it will result in total freedom from the power
- ^ S. Ha,
R. Larsen, and R. I. Masel, "Performance characterization of
Pd/C nanocatalyst for direct formic acid fuel cells,"
Journal of Power Sources, 144, 28-34 (2005)
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