Scientists at Los Alamos National Laboratory have developed a new class of hydrogen fuel-cell catalysts that exhibit promising activity and stability. The catalysts are made of low-cost nonprecious metals entrapped in a heteroatomic-polymer structure, instead of platinum materials typically used in fuel cells. Replacing platinum with the non-precious metal composite could reduce the cost of hydrogen fuel cells.
In research published recently in Nature, Los Alamos scientists Rajesh Bashyam and Piotr Zelenay describe tests conducted on a cobalt-polypyrrole-carbon (Co-PPY-XC72) composite. The composite, consisting of cobalt, polymer and carbon, was developed in research aimed at developing low-cost non-platinum catalysts for the polymer electrolyte fuel-cell (PEFC) cathode (site of the oxygen reduction reaction).
While the electrical energy producing activity of the catalyst is lower than that of platinum-based catalysts used in polymer electrolyte fuel cells, the new material shows exceptional performance stability for more than one hundred hours of continuous testing, a result never before obtained with non-precious metal catalysts in PEFCs. The materials perform reproducibly and at higher voltages.
Besides being made of inexpensive and environmentally benign materials, the chief advantage of these composite catalysts for oxygen reduction is that they can operate in the acidic environment of the polymer electrolyte fuel cell.—Piotr Zelenay
Bashyam and Zelenay are investigating the nature of catalysts in a variety of composites. They are also part of a larger Laboratory effort aimed at developing new catalyst and electrode structures that could increase the current output from fuel cells.
The two biggest obstacles in making a commercially viable fuel cell have traditionally been high cost and inadequate durability. Our focus at Los Alamos is to attack those obstacles as a system in which you simultaneously strive for lower costs and higher durability.—Ken Stroh, program manager for the Los Alamos fuel-cell effort
The US Department of Energy’s Office of Hydrogen, Fuel Cells and Infrastructure Technologies funds much of the PEFC fuel cell research at Los Alamos.
“A class of non-precious metal composite catalysts for fuel cells”; Rajesh Bashyam and Piotr Zelenay; Nature 443, 63 - 66 (07 September 2006); doi:10.1038/nature05118