Saturday, April 4, 2009

More Efficient Palladium Fuel Cell Catalysts

We use many small devices in our everyday life. And each small device needs power. Now devices are becoming smaller with each passing day hence scientists are finding out ways to power them.

Scientists are putting their effort on a material known as palladium. This may turn out to be a hopeful substance in near future to power fuel cells. Another advantage that palladium has over other metals is, it is cheaper and more abundant. Vismadeb Mazumder who is a graduate student and assisting chemistry professor Shouheng Sun in writing the paper, explains the benefits, “This approach is very novel. It works. It’s two times as active, meaning you need half the energy to catalyze. And it’s four times as stable.”

Palladium nanoparticles are used by others too, to power fuel cells. Researchers are facing some hurdles in creating palladium nanoparticles with enough active surface area to make catalysis efficient in fuel cells. They have another problem of preventing particles from clumping together during the chemical processes that convert a fuel source into electricity. Now two Brown University chemists are trying to overcome those hurdles. They are claiming to develop palladium nanoparticles with 40% larger surface area. They also tackled the problem of the clustering of palladium nanoparticles. This catalyst’s shape remains intact four times longer that what is presently offered by others.

How did they achieve this feat? How they retained the shape of the palladium nanoparticles and how they increased the surface area? Mazumder and Sun produced palladium nanoparticles 4.5 nanometers in size. They fastened the nanoparticles to a carbon platform at the anode end of a direct formic acid fuel cell. What is novel here? They did something original. They utilized weak binding amino ligands to keep the palladium nanoparticles separate and at the same size as they’re attached to the carbon platform. This approach is the key to increasing the surface area. Because when the particles remained separate and uniform in size, they increased the available surface area on the platform and raised the efficiency of the fuel cell reaction.

That’s not all. The specialty of the legands is they can be “washed” from the carbon platform without endangering the integrity of the separated palladium nanoparticles. This step proved crucial for the duo researchers and better than previous attempts by other scientists. If you tried to remove binding ingredients it caused the particles to lose their rigid sizes and clump together, which gums up the reaction. Mazumder stated, “We managed to ebb the decay of our catalyst by our approach. We made high-quality palladium nanoparticles, put them efficiently on a support, then removed them from the stabilizers efficiently without distorting catalyst quality.”