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Vicenza, Italy

Lanza R.,KTH Royal Institute of Technology | Bersani M.,University of Padua | Conte L.,QID Nanotechnologies Srl | Martucci A.,University of Padua | And 6 more authors.
Journal of Physical Chemistry C

We present a synthetic strategy for the preparation of palladium-tin alloy and intermetallic nanoparticles. Complexes of palladium(II) and tin(IV) precursors in oleylamine were thermally decomposed in an organic solution in the presence of reducing moieties, leading to the formation of monodispersed nanoparticles with varying crystallographic structures. We found that the nanoparticles crystalline structure closely follows the bulk material phase diagram. The nanoparticles were supported on Al2O3 and their reactivity tested as catalysts for the preferential oxidation of CO in excess of hydrogen (PROX). Different Pd/Sn and O2/CO ratios have been investigated, and the structure-reactivity correlation highlighted. With increasing tin content, the CO ignition temperature remarkably lowers and the CO conversion rate increases, up to the formation of intermetallic phases that concurrently determine a reduction in the catalyst activity; the selectivity of the pure palladium references is preserved. (Graph Presented). © 2014 American Chemical Society. Source

Bersani M.,University of Padua | Conte L.,QID Nanotechnologies Srl | Martucci A.,University of Padua | Guglielmi M.,University of Padua | And 4 more authors.

The preparation of palladium alloy nanoparticles is of great interest for many applications, especially in catalysis. Starting from presynthesized nanoparticles of a less noble metal, a transmetallation reaction involving a redox process at the nanoparticle surface can be exploited to modify the nanoparticle composition and crystalline phase. As an example, monodispersed ε-cobalt and face-centered cubic copper nanoparticles were synthesized in organic solvents at high temperature and the as-formed nanoparticles were reacted with palladium(ii) hexafluoroacetylacetonate resulting in the formation of alloyed nanoparticles whose composition closely follows the reactant ratio. The oxidative state of the nanoparticle surface greatly affects the success of the transmetallation reaction and a reduction treatment was necessary to achieve the desired final product. Electron microscopy and X-ray diffraction showed that for cobalt a limiting palladium content for the ε-phase alloy is found, above which an fcc alloy nucleates, while for copper the fcc crystalline phase is preserved throughout the whole composition range. © 2013 The Royal Society of Chemistry. Source

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