Issue Date: June 25, 2012
Three-Part Catalyst Works Like A Charm
A three-component metal alloy mediates electrocatalytic reduction of oxygen to water more effectively than pure platinum and platinum-based bimetallic catalysts, according to a study led by researchers at Argonne National Laboratory (J. Phys. Chem. Lett., DOI: 10.1021/jz300563z). Oxygen reduction is a critical reaction in fuel cells and metal-air batteries. Nanoparticulate platinum supported on carbon is considered the best catalyst for that reaction, but kinetic factors prevent platinum from reaching its theoretical catalytic effectiveness. In addition, the metal is costly and relatively scarce. Recent investigations have focused on platinum-based bimetallic substitutes, but three-component systems have not been explored systematically. Vojislav R. Stamenkovic and coworkers prepared bimetallic and trimetallic thin films of platinum alloyed with iron, cobalt, and nickel and compared their measured electrocatalytic activities with their predicted oxygen binding energies. Guided by those results, the team synthesized supported nanoparticle catalysts of the most promising alloys. The group’s tests show that a catalyst consisting of 6-nm-diameter particles of PtCoNi (atomic ratio roughly 3:0.5:0.5) is more active for oxygen reduction than platinum-based bimetallic catalysts and four times as active as pure platinum.
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