Technology.am (May 17, 2009) — Material scientists at Washington University in St. Louis have developed a technique for bimetallic catalyst comprised of palladium and platinum that outperforms commerical catalysts, which could enable a cost effective fuel cell technology and ultimately provide cleaner fuels worldwide.
Younan Xia, Ph.D., the James M. McKelvey Professor of Biomedical Engineering at Washington University led a team of scientists at Washington University and the Brookhaven National Laboratory in developing a bimetallic catalyst comprised of a palladium core or “seed” that supports dendritic platinum branches, or arms, that are fixed on the nanostructure, consisting of a nine nanometer core and seven nanometer platinum arms.
They synthesized the catalysts by sequentially reducing precursor compounds to palladium and platinum with L-ascorbic acid (that is, Vitamin C) in an aqueous solution. The catalysts have a high surface area, invaluable for a number of applications besides in fuel cells, and are robust and stable.
They tested how the catalysts performed in the oxygen reduction reaction process in a fuel cell, which determines how large a current will be generated in an electrochemical system similar to the cathode of a fuel cell.
They found that their bimetallic nanodendrites, at room temperature, were two-and-a-half times more effective per platinum mass for this process than the state-of-the-art commercial platinum catalyst and five times more active than the other popular commercial catalyst. At 60 C the performance almost meets the targets set by the U.S. Department of Energy.
The Department of Energy has estimated for widespread commercial success the “loading” of platinum catalysts in a fuel cell should be reduced by four times in order to slash the costs.
This technique is expected to substantially reduce the loading of platinum, making a more robust catalyst that won’t have to be replaced often, and making better use of a very limited and very expensive supply of platinum in the world.