PROVIDENCE, R.I. [Brown University] Even small devices need power, and much of that juice comes from fuel cells. As these devices become even smaller, the rush is on to find more efficient ways to power them.
In the last several years, scientists have discovered that palladium, a metal, is a strong candidate for providing that initial boost that helps fuel cells go. Palladium is far cheaper than another popular fuel cell catalyst, platinum, and it's more abundant.
But researchers have wrestled with creating palladium nanoparticles with enough active surface area to make catalysis efficient in fuel cells while preventing particles from clumping together during the chemical processes that convert a fuel source to electricity. Two Brown University chemists have found a way to overcome those challenges.
The scientists report in the online edition of the Journal of the American Chemical Society that they have produced palladium nanoparticles with about 40 percent greater surface area than commercially available palladium particles. The Brown catalysts also remain intact four times longer than what's currently available.
"This approach is very novel. It works," said Vismadeb Mazumder, a graduate student who joined chemistry professor Shouheng Sun on the paper. "It's two times as active, meaning you need half the energy to catalyze. And it's four times as stable."
Mazumder and Sun created palladium nanoparticles 4.5 nanometers in size. They attached the nanoparticles to a carbon platform at the anode end of a direct formic acid fuel cell. The researchers then did something new: They used weak binding amino ligands to keep the palladium nanoparticles separate and at the same size as they're attached to the carbon platform. By keeping the particles separate and uniform in size, they increased the available surface area on the platform and raised the efficiency of the fuel cell reaction.
"It just works better,
|Contact: Richard Lewis|