Alloy Catalyst Beats Pure Platinum

Chemical engineers at the University of Houston have developed a new type of platinum-alloy catalyst that's four to five times better at reducing oxygen than platinum alone (Angew. Chem. Int. Ed., DOI: 10.1002/anie.200703331). The finding could be a boon to fuel cells that rely on the O₂-reducing reaction. The catalyst, in the form of nanoparticles made up of a copper-cobalt-platinum alloy, has the highest reported activity for O₂ reduction in a polymer electrolyte membrane fuel cell, according to Peter Strasser, who led the research effort. The catalyst's active phase is formed in situ (shown: Cu = red, Co = blue, Pt = gray). When current is applied to the electrode, some of the copper and cobalt selectively dissolve out of the alloy and migrate into the polymer membrane. A platinum-rich shell is left behind to catalyze the reaction. Strasser thinks that the bump in catalytic activity comes from the structural characteristics of the nanoparticle surface, where the distances between platinum atoms are shortened, thanks to stabilization from the alloy core.