Controlling the electronic structure and surface strain of a nanoparticle catalyst has become an important strategy to tune and to optimize its catalytic efficiency for a chemical reaction. Using density functional theory (DFT) calculations, we predicted that core/shell M/CuPd (M = Ag, Au) NPs with a 0.8 or 1.2 nm CuPd2 shell have similar but optimal surface strain and composition and may surpass Pt in catalyzing oxygen reduction reactions. We synthesized monodisperse M/CuPd NPs by the coreduction of palladium acetylacetonate and copper acetylacetonate in the presence of Ag (or Au) nanoparticles with controlled shell thicknesses of 0.4, 0.75, and 1.1 nm and CuPd compositions and evaluated their catalysis for the oxygen reduction reaction in 0.1 M KOH solution. As predicted, our Ag/Cu37Pd63 and Au/Cu40Pd60 catalysts with 0.75 and 1.1 nm shells were more efficient catalysts than the commercial Pt catalyst (Fuel Cells Store), with their mass activity reaching 0.20 A/mg of noble metal at -0.1 V vs Ag/AgCl (4 M KCl); this was over 3 times higher than that (0.06 A/mg Pt) from the commercial Pt. These Ag(Au)/CuPd nanoparticles are promising non-Pt catalysts for oxygen reduction reactions.

We report a facile synthesis of monodisperse NiPd alloy nanoparticles (NPs) and their assembly on graphene (G) to catalyze the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of R-NO 2 and/or R-CN to R-NH 2 in aqueous methanol solutions at room temperature. The 3.4 nm NiPd alloy NPs were prepared by coreduction of nickel(II) acetate and palladium(II) acetlyacetonate by borane-tert-butylamine in oleylamine and deposition on G via a solution phase self-assembly process. G-NiPd showed composition-dependent catalysis on the tandem reaction with G-Ni 30 Pd 70 being the most active. A variety of R-NO 2 and/or R-CN derivatives were reduced selectively into R-NH 2 via G-Ni 30 Pd 70 catalyzed tandem reaction in 5−30 min reaction time with the conversion yields reaching up to 100%. Our study demonstrates a new approach to GNiPd-catalyzed dehydrogenation of AB and hydrogenation of R-NO 2 and R-CN. The G-NiPd NP catalyst is efficient and reusable, and the reaction can be performed in an environment-friendly process with short reaction times and high yields.

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MPd (M = Co, or Cu) nanoparticles (NPs) were synthesized by borane-amine reduction of metal acetylacetonates. The size of the MPd NPs was controlled at 3.5 nm and their compositions were tuned by the molar ratios of the metal precursors. These MPd NPs were active catalysts for electrochemical oxidation of formic acid and the Cu30Pd70 NPs showed the highest mass activity at 1192.9 A gPd(-1), much higher than 552.6 A gPd(-1) obtained from the 3.5 nm Pd NPs. Our synthesis provides a facile route to MPd NPs, allowing further investigation of MPd NP catalysts for electrochemical oxidation and many other chemical reactions.

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