Material scientists at Washington University in St. Louis have developed a technique for a bimetallic fuel cell catalyst that is efficient, robust and two to five times more effective than commercial catalysts. The novel technique eventually will enable a cost effective fuel cell technology, which has been waiting in the wings for decades, and should give a boost for cleaner use of 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.
Xia and his team 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 typical operation temperature of a fuel cell), 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.
|Contact: Younan Xia|
Washington University in St. Louis