FUEL CELLS—ENERGY FOR A POWER-HUNGRY WORLD - Chemistry: Notable Research and Discoveries - page 150

FIndIngTHEBESTCATAlyST
One of the most daunting issues is the catalyst. The reactions at the
electrodes tend to go slowly, and making or coating the electrode with
a catalyst is essential to speed things up. Platinum is one of the most ef-
fective catalysts because it binds the reactants and holds them in place
so that the reaction can proceed. But the problem is cost—platinum is
a rare metal and not at all cheap. An ounce (28.6 g) of platinum costs
about $1,200 as of May 2009. Compare that to gold, a precious metal
that costs about $970 per ounce (28.6 g) as of May 2009. Fuel cell elec-
trodes would be cheaper if they were made of gold (but gold is not an
effective catalyst)!
Fuel cell power is often measured in watts or kilowatts (1,000 watts),
as is most electrical devices. Scientists use the term power as a measure
of the energy per unit time. (A watt equals one joule, an energy unit, di-
vided by one second.) For example, 60 watts is a common power rating
for an incandescent lightbulb. In the United States, the power of auto-
mobile engines is often described in horsepower, an old unit for power.
One horsepower equals about 746 watts. A typical automobile engine is
rated at 170 horsepower, or 127 kilowatts. Producing this much power
from a fuel cell requires only a few ounces or dozens of grams of plati-
num. But with the steep price of platinum, this amounts to $3,000 or
more, about as much as the cost of a whole gasoline engine. Searching
for platinum alternatives is an active area of research, but so far most of
the candidates are pricey as well.
Researchers are looking at ways to reduce the amount of platinum
yet retain the catalytic activity. Peter Strasser, a researcher at the Uni-
versity of Houston in Texas, and his colleagues are trying to develop a
platinum alloy that will do the job. An alloy such as bronze is a combi-
nation of elements, which in the case of bronze are tin and copper. En-
gineers often use alloys because they offer properties that are superior
to those of a single metal, as described in chapter 1. A platinum alloy
that acts as an effective catalyst in fuel cell electrodes yet contains less
platinum would save a substantial amount of money.
As reported at Science Daily in 2007, Strasser and his colleagues dis-
covered an alloy of copper (Cu), cobalt (Co) and platinum (Pt) that
exceeded even pure platinum's catalytic activity for the reduction of
oxygen (one of the important reactions taking place in fuel cells). The
material consists of tiny particles called nanoparticles, described in