Carbon-supported PtM ͑M = Fe, Co, Ni and Cu͒ catalysts have been synthesized by precipitating the M n+ ions as hydroxides in presence of a commercial carbon-supported Pt catalyst followed by heat treatment in a 90% Ar-10% H 2 mixture at 900°C for 1 h. X-ray diffraction indicates the PtFe and PtCo alloys thus obtained to have an ordered structure while the PtNi and PtCu alloys have a disordered FCC structure. Structural analysis of PtFe and PtCo after annealing at various temperatures 500°C ഛ T ഛ 900°C for 1 h indicates the ordering to be maximized for an annealing temperature of around 600°C. Evaluation of the PtM alloy catalysts for oxygen reduction in proton exchange membrane fuel cells ͑PEMFCs͒ indicates that the alloys with the ordered structures have higher catalytic activity with lower polarization losses than Pt and the disordered PtM alloys. With the ordered phases, the activity increases with the extent of ordering. The enhanced catalytic activity is explained based on an optimal structural and electronic features consisting of optimum number of Pt and M nearest neighbors, d-electron density in Pt, atomic configuration on the surface, and Pt-Pt distance.

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Improving efficiency and reducing overall cost are two key issues to the commercialization of fuel cell powered vehicles. Electrocatalysts play an important role, particularly in the cathode, where the oxygen reduction reaction is sluggish and the noble metal loading is relatively high. To discover less expensive and more active cathode catalysts, a novel combinatorial workflow has been developed to investigate alloy-based electrocatalysts. In addition to the discovery program, various synthesis technologies have been studied and developed to engineer nanoscale catalyst particles with controllable size, monodispersity, and microcomposition. The progress of these research activities is reported with particular attention focused on the activity-stabilitycomposition relationship for a series of platinum-based metal alloys.