Shape evolution of gold nanoparticles

Journal of Nanoparticle Research (Impact Factor: 2.28). 01/2010; 12(2):655-661. DOI: 10.1007/s11051-009-9612-3

ABSTRACT The tetraoctylammonium bromide-stabilized gold nanoparticles have been successfully fabricated. The shape evolution of these
nanoparticles under different annealing temperatures has been investigated using high-resolution transmission electron microscopy.
After an annealing at 100°C for 30min, the average diameters of the gold nanoparticles change a little. However, the shapes
of gold nanoparticles change drastically, and facets appear in most nanoparticles. After an annealing at 200°C for 30min,
not only the size but also the shape changes a lot. After an annealing at 300°C for 30min, two or more gold nanoparticles
coalesce into bigger ones. In addition, because of the presence of Cu grid during the annealing, some gold particles become
the nucleation sites of Cu2O nanocubes, which possess a microstructure of gold-particle core/Cu2O shell. These Au/Cu2O heterostructure nanocubes can only be formed at a relatively high temperature (≥300°C). The results can provide some insights
on controlling the shapes of gold nanoparticles.

  • Source
    Gold Nanoparticles in Analytical Chemistry, Comprehensive Analytical Chemistry edited by M. Valcárcel, A.I. López-Lorente, 10/2014: chapter Microscopic Techniques for the Characterization of Gold Nanoparticles: pages 257-299; Elsevier., ISBN: 9780444632852
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    ABSTRACT: Interfacing anisotropic gold nanostructures with graphene can open up new avenues for modifying the light–matter interaction of graphene. A chemical route is explored to synthesize branched gold nanostructures on reduced graphene oxide (rGO) layers by in situ reduction, assisted by binary surfactant mixtures containing tetraoctylammonium bromide with cetyltrimethy­lammonium bromide, sodium dodecylsulfate, or sodium citrate. The hybrid material self-assembles at a liquid/liquid interface forming a free-standing film. Electron microscopy studies reveal the morphology, microstructure, and crystallinity of the hybrids. The gold nanostructures are branched in three dimensions and possess various shapes, such as irregular stars, multipods, and spiky features, interspersed with rGO layers. The hybrids exhibit plasmon modes in the visible and near-infrared region due to the shape anisotropy. The enhancement effect of the spiky features is also observed in the Raman spectra. The growth mechanism of the branched nanostructures is followed by kinetic studies and indicates that the formation of multiple twinned crystals is the key factor for branching.
    Particle and Particle Systems Characterization 11/2014; 31(11). DOI:10.1002/ppsc.201400037 · 0.54 Impact Factor
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    ABSTRACT: The structure formation in gold nanoparticles 1.6–5.0 nm in diameter is studied by molecular dynamics simulation using a tight-binding potential. The simulation shows that the initial fcc phase in small Au clusters transforms into other structural modifications as temperature changes. As the cluster size increases, the transition temperature shifts toward the melting temperature of the cluster. The effect of various crystallization conditions on the formation of the internal structure of gold nanoclusters is studied in terms of microcanonical and canonical ensembles. The stability boundaries of various crystalline isomers are analyzed. The obtained dependences are compared with the corresponding data obtained for copper and nickel nanoparticles. The structure formation during crystallization is found to be characterized by a clear effect of the particle size on the stability of a certain isomer modification. Nickel and copper clusters are shown to exhibit common features in the formation of their structural properties, whereas gold clusters demonstrate much more complex behavior.
    Journal of Experimental and Theoretical Physics 02/2013; 116(2). DOI:10.1134/S106377611302009X · 0.93 Impact Factor


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