Chemists have overcome the challenge of using palladium catalysts for fuel cell reactions. The active surface area of palladium nanoparticles produced by scientists is about 40% larger than that of commercially available palladium particles, and the intact time of the nanoparticles is four times longer.
Even small devices require electricity, and most of the electricity comes from fuel cells. As these devices become smaller and smaller, people are eager to find more effective ways to power them.
In the past few years, scientists have discovered that palladium is a powerful candidate that can provide the initial driving force to help fuel cells operate. Palladium is much cheaper than another popular fuel cell catalyst, platinum, and its reserves are more abundant.
However, researchers have been working hard to produce palladium nanoparticles with sufficient active surface area to catalyze efficiently in fuel cells and prevent particles from gathering together in the chemical process of converting fuel sources into electricity. Two chemists at Brown University have found ways to overcome these challenges.
Scientists reported in the online edition of the Journal of the American Chemical Society that they had produced palladium nanoparticles with a surface area about 40% larger than that of commercially available palladium particles. The intact time of Brown catalyst is four times that of currently available catalysts.
This method is very novel. It is indeed effective, "said graduate student Vismadeb Mazumder, who studied the paper together with chemistry professor Sun Shouheng. Its activity is twice that of the original, which means you need half the energy to catalyze. And its stability is four times that of the original
Mazumder and Sun created palladium nanoparticles with a size of 4.5 nanometers. They attach nanoparticles to the carbon platform at the anode end of direct formic acid fuel cells. Then, the researchers did some new things: they used weakly bound amino ligands to maintain the separation of palladium nanoparticles and maintain the same size when they adhered to the carbon platform. By maintaining particle separation and uniform size, they increase the available surface area on the platform and improve the efficiency of fuel cell reactions.
It works better, "Sun said.
Another special feature of ligands is that they can be "washed" off the carbon platform without damaging the integrity of the separated palladium nanoparticles. Mazumder emphasized that this is an important step, as previous attempts to remove binding components resulted in the particles losing their rigid size and gathering together, which hindered the reaction.
The Brown University research team stated that during the 12 hour experiment, their catalyst lost 16% of its surface area, while the commercial catalyst lost 64% of its surface area.
We successfully slowed down the decay of the catalyst through our method, "said Ma Zude, who was working in Sun Labs for his second year. We manufactured high-quality palladium nanoparticles, efficiently placed them on the scaffold, and then effectively removed them from the stabilizer without affecting the quality of the catalyst
Scientists at Brown University are currently researching various palladium based catalysts with enhanced activity and stability for future fuel cell applications.
Mazumder said, "We hope to reduce costs through similar activities
This study was funded by the Materials Research Department of the National Science Foundation of the United States and the Brown Seed Foundation.
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