Hydrogen fuel cells, like those found
in some “green” vehicles, have a lot of promise as an alternative fuel source,
but making them practical on a large scale requires them to be more efficient
and cost effective.
A research team from the University
of Central Florida (UCF) may have found a way around both hurdles.
The majority of hydrogen fuel cells
use catalysts made of a rare and expensive metal—platinum. There are few
alternatives because most elements can’t endure the fuel cell’s highly acidic
solvents present in the reaction that converts hydrogen’s chemical energy into
electrical power. Only four elements can resist the corrosive process—platinum,
iridium, gold, and palladium. The first two are rare and expensive, which makes
them impractical for large-scale use. The other two don’t do well with the
chemical reaction.
UCF Professor Sergey Stolbov and
postdoctoral research associate Marisol Alcántara Ortigoza focused on making
gold and palladium better suited for the reaction.
They created a sandwich-like
structure that layers cheaper and more abundant elements with gold and
palladium and other elements to make it more effective.
The outer monoatomic layer (the top
of the sandwich) is either palladium or gold. Below it is a layer that works to
enhance the energy conversion rate but also acts to protect the catalyst from
the acidic environment. These two layers reside on the bottom slice of the
sandwich—an inexpensive substrate (tungsten), which also plays a role in the
stability of the catalyst.
“We are very encouraged by our first
attempts that suggest that we can create two cost-effective and highly active
palladium- and gold-based catalysts for hydrogen fuel cells, a clean and
renewable energy source,” Stolbov said.
Stolbov’s work was recently published
in The Journal of Physical
Chemistry Letters.
By creating these structures, more
energy is converted, and because the more expensive and rare metals are not
used, the cost could be significantly less.
Stolbov said experiments are needed
to test their predictions, but he says the approach is quite reliable. He’s
already working with a group within the U.S. Department of Energy to determine
whether the results can be duplicated and have potential for large-scale
application.
If a way could be found to make
hydrogen fuel cells practical and cost effective, vehicles that run on gasoline
and contribute to the destruction of the ozone layer could become a thing of
the past.
