Cells F 3000Stabilization of Platinum Oxygen-Reduction Electrocatalysts Using Gold Clusters. -Pt oxygen-reduction fuel cell electrocatalysts are stabilized against dissolution under potential cycling regimes (a continuing problem in vehicle applications) by modifying Pt nanoparticles with Au clusters. There are insignificant changes in the activity and surface area of Au-modified Pt under the oxidizing conditions of the O2 reduction reaction and potential cycling between 0.6 and 1.2 V in over 30,000 cycles, in contrast to sizable losses with the pure Pt catalyst under the same conditions. In situ XANES and voltammetry data suggest that the Au clusters confer stability by raising the Pt oxidation potential. -(ZHANG, J.; SASAKI, K.; SUTTER, E.; ADZIC, R. R.; Sci.

Catalysts H 2000Platinum Monolayer on Nonnoble Metal-Noble Metal Core-Shell Nanoparticle Electrocatalysts for O2 Reduction. -New O2 electrocatalysts with a high activity and very low noble metal content consisting of Pt monolayers deposited on the surfaces of carbon-supported non-noble-noble metal core-shell nanoparticles such as Pt/Au/Ni, Pt/Pd/Co, and Pt/Pt/Co are synthesized. The core-shell nanoparticles are formed by impregnation of Vulcan X-72C carbon with mixed solutions of noble and non-noble metal salts such as AuCl3, NiCl2, K2PtCl4, CoCl2, and PdCl2. A Pt monolayer is deposited by galvanic displacement of a Cu monolayer deposited at underpotentials. The mass activity of all three Pt monolayer electrocatalysts is more than an order of magnitude higher than that of a commercial Pt-C electrocatalyst. Because the new catalysts contain only a fractional amount of Pt and a very small amount of another noble metal, the cost of fuel cells could be lowered considerably. -(ZHANG, J.; LIMA, F. H. B.; SHAO, M. H.; SASAKI, K.; WANG, J. X.; HANSON, J.; ADZIC*, R. R.; J.