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Many binary late transition metal systems have large bulk miscibility gaps, and a variety of synthetic strategies have been developed to generate these non-equilibrium alloys as nanoparticles. While many of these methods strive to co-nucleate both elements by exploiting fast reduction kinetics or co-sequestration within a confined space, we show here that simple room-temperature borohydride co-reduction of appropriate aqueous metal salt solutions yields alloy nanoparticles in the bulk-immiscible Au–Rh, Au–Pt, Pt–Rh, and Pd–Rh systems. The compositions can be tuned across the entire Au1−xRhx, Au1−xPtx, Pt1−xRhx, and Pd1−xRhxsolid solutions by varying the ratio of metal salt reagents, and they form in the presence of a variety of molecular and polymeric surface stabilizers. Reaction pathway studies on the model Au–Rh system suggest that the alloy nanoparticles form viaa “conversion chemistry” mechanism: Au nanoparticle templates nucleate first, followed by diffusion of Rh to form homogeneous Au–Rh alloy nanoparticles. The alloy nanoparticles tend to be agglomerated, but this can be minimized by forming the nanoparticles directly on catalytically relevant high surface area carbon and biological supports, e.g.Vulcan carbon and wild-type M13 bacteriophage. [ABSTRACT FROM AUTHOR]

Binary intermetallic compounds have been synthesized in edible plant and seed oils through the reaction of molten metal dispersions of low-melting p-block metals with late transition metal powders. Specifically, apricot kernel, almond, safflower, and canola oils have been used to synthesize FeSn2, Ni3Sn4, CoSn3, CoGa3, Cu6Sn5, and Bi3Ni. This low-temperature strategy yields bulk-scale products that are highly crystalline, and the solvents used to synthesize them can be re-used several times. [ABSTRACT FROM AUTHOR]

Multi-metal nanoparticles, particularly alloys and intermetallic compounds, are useful catalysts for a variety of chemical transformations. Supported intermetallic nanoparticle catalysts are usually prepared by depositing precursors onto a support followed by high-temperature annealing, which is necessary to generate the intermetallic compound but causes sintering and minimizes surface area. Here we show that solution chemistry methods for converting metal nanoparticles into intermetallic compounds are applicable to supported nanoparticle catalyst systems. Unsupported nanocrystalline Pt can be converted to nanocrystalline PtSn, PtPb, PtBi, and FePt3 by reaction with appropriate metal salt solutions under reducing conditions. Similar reactions convert Al2O3, CeO2, and carbon-supported Pt nanoparticles into PtSn, PtPb, PtSb, Pt3Sn, and Cu3Pt. These reactions generate supported alloy and intermetallic nanoparticles directly in solution without the need for high temperature annealing or additional surface stabilizers. These supported intermetallic nanoparticles are catalytically active for chemical transformations such as formic acid oxidation (PtPb/Vulcan) and CO oxidation (Pt3Sn/graphite). Notably, PtPb/Vulcan XC-72 was found to electrocatalytically oxidize formic acid at a lower onset potential (0.1 V) than commercial PtRu/Vulcan XC-72 (0.4 V). [ABSTRACT FROM AUTHOR]