Pt-M (M = Fe, Co, Ni and Cu) electrocatalysts synthesized by an aqueous route for proton exchange membrane fuel cells

Nanostructured Pt-M (M = Fe, Co, Ni, and Cu) alloy catalysts synthesized by a low temperature (70 degreesC) reduction procedure with sodium formate in aqueous medium have been investigated for oxygen reduction in sulfuric acid and as cathodes in single proton exchange membrane fuel cells (PEMFC). The Pt-M alloy catalysts show improved catalytic activity towards oxygen reduction compared to pure platinum. Among the various alloy catalysts investigated, the Pt-Co catalyst shows the best performance with the maximum catalytic activity and minimum polarization occurring at a Pt:Co atomic ratio of around 1:7. While mild heat treatments at moderate temperatures (200 degreesC) improve the catalytic activity due to a cleaning of the surface oxides, annealing at elevated temperatures (900 degreesC) degrade the activity due to an increase in particle size. (C) 2002 Elsevier Science B.V. All rights reserved.