Simple Synthesis of Monodisperse Ultrasmall Au Icosahedral Nanoparticles
Résumé
Ultra-small metal nanoparticles (NPs) with a mean diameter below 2 nm are being intensively studied due to their unique structural and chemical properties. At such small sizes, metal particles can appear as various polyhedra with different atomic structures depending on whether electronic effects, surface energy or the nucleation mechanism govern their crystallization. Therefore, the synthesis of monodisperse nanoparticles of a very small size and well-defined structure requires a good understanding of the different steps of the crystallization process, which can be achieved by conducting and coupling in situ studies at different length and time scales. In this article, we describe the synthesis of ultra-small gold NPs by reduction of HAuCl4 in solution of oleylamine (OY) in hexane using trialkylsilanes as reducing agents. Thanks to time-resolved in situ small angle X-ray scattering and X-ray absorption spectroscopy kinetic studies, a competition between nucleation of Au NPs from a solution containing Au(III) clusters and crystallization of a lamellar phase of composition OY-Au(I)-Cl was revealed. In situ X-ray diffraction and Pair Distribution Function analysis (PDF) showed that the first chemical pathway leads to icosahedral NPs while the reduction of OY-Au(I)-Cl leads to fcc NPs.
Domaines
MatériauxOrigine | Fichiers produits par l'(les) auteur(s) |
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