Colloidal nanocrystal synthesis and the organic–inorganic interface

Yin, Yadong; Alivisatos, A. Paul

doi:10.1038/nature04165

Cited by 3,095 publications

(2,830 citation statements)

References 65 publications

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“…Although the organic species strongly influence the structural, compositional, and morphological characteristics of the inorganic product and thus offer a versatile tool for tailoring particle size, shape, composition, and surface properties, this is only possible on an empirical basis as long as the organic-inorganic interface is not completely understood on a molecular level and as long as there is no detailed information available about how organic molecules bind and pack on nanocrystal surfaces. 55 …”

Section: Resultsmentioning

confidence: 99%

Nonaqueous Sol–Gel Routes to Metal Oxide Nanoparticles

2007

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Sol-gel routes to metal oxide nanoparticles in organic solvents under exclusion of water have become a versatile alternative to aqueous methods. In comparison to the complex aqueous chemistry, nonaqueous processes offer the possibility of better understanding and controlling the reaction pathways on a molecular level, enabling the synthesis of nanomaterials with high crystallinity and well-defined and uniform particle morphologies. The organic components strongly influence the composition, size, shape, and surface properties of the inorganic product, underlining the demand to understand the role of the organic species at all stages of these processes for the development of a rational synthesis strategy for inorganic nanomaterials.

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Section: Resultsmentioning

confidence: 99%

Nonaqueous Sol–Gel Routes to Metal Oxide Nanoparticles

2007

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“…The resulting high nucleation and growth rates make "kinetic size focusing" possible, favoring formation of monodisperse nanocrystals. 1,19 Indeed, assynthesized silver nanocrystals have narrow size distributions, as seen in the transmission electron microscopy (TEM) image and the observed particle diameter statistics for a typical sample ( Fig 1A). All the nanocrystals possess an apparently spherical shape and the average diameter is 11.0 ± 1.1 nm.…”

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confidence: 87%

“…1,2 The literature now contains several cases with chemical transformations being accompanied by varying degrees of modification of properties, including crystal structure and particle shape. [3][4][5] As a recent example, we demonstrated that as-synthesized metallic nanocrystals yield, upon oxidation, nanostructures with modified morphologies such as hollow particles.…”

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Faceting of Nanocrystals during Chemical Transformation: From Solid Silver Spheres to Hollow Gold Octahedra

et al. 2006

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Sustained progress in nanocrystal synthesis has enabled recent use of these materials as inorganic, macromolecular precursors that can be chemically transformed into new nanostructures. 1, 2 The literature now contains several cases with chemical transformations being accompanied by varying degrees of modification of properties, including crystal structure and particle shape. [3][4][5] As a recent example, we demonstrated that as-synthesized metallic nanocrystals yield, upon oxidation, nanostructures with modified morphologies such as hollow particles. 6 This morphological change derives from directional material flows due to differing diffusivities for the reacting atomic species, in a nanoscale version of the well-known Kirkendall Effect. This general methodology has since been extended by other groups to produce nanostructures with various compositions and shapes. [7][8][9][10] Galvanic replacement reactions have been demonstrated to also produce hollow nanostructures. Xia et al. reported cases where a replacement reaction took place uniformly around Ag cubes of ~100 nm size, leading to formation of Au nanoboxes. The exterior shape of the nanoboxes tends to largely reproduce that of the sacrificial Ag counterparts. 11-15 Here, we report that performing the same replacement reaction on silver nanocrystals that are an order of magnitude smaller leads to significant changes in the external morphology of the Au shells as the reaction proceeds, while still creating a central void in each particle. Specifically, single crystalline silver nanoscrystals with a spherical shape act in the presence of Au 3+ as precursors for formation of hollow Au nanocrystals with truncated octahedral shape. The growth of significantly faceted particles from spherical precursors is made possible by the enhanced role of surface effects in our smaller nanocrystals. Production of hollow Au nanocrystals with faceted geometry allows increased tunability of optical properties as the surface plasmon resonance spectra of a hollow metallic nanocrystal depends strongly not only on the shell thickness, but also on the detailed shape. 16,17 To produce Ag nanocrystals with reduced sizes and improved monodispersity, we performed the synthesis using a modification of the polyol process in an organic solvent and at high temperature. 6,18 The silver salt AgNO 3 was reduced by a long chain polyol such as 1,2-hexadecanediol using an organic solvent, o-dichlorobenzene (DCB). Oleylamine was present as a surfactant. Near instant formation of silver nanocrystals upon reaction was indicated by the originally colorless solution turning dark brown. The transformation of solid nanocrystals into hollow ones was performed through galvanic replacement by dropwise addition of gold (III) chloride solution to diluted silver colloidal solution until the solution changed in color from dark yellow to blue. In this reaction, oleylamine likely serves two purposes. First, it solubilizes the precursors AgNO 3 and AuCl 3 in DCB. Second, it acts as a surfactant that controls t...

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“…Starting with preparations of simple objects like spherical nanoparticles [1,2], the field is now moving toward more and more sophisticated structures where size, shape and connectivity of multiple parts of a multicomponent structure can be tailored in an independent and predictable manner [3,4]. Traditional molecular chemistry has proven that synthetic methodology should rely on a toolbox of robust and reproducible techniques.…”

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Seeded Growth of Highly Luminescent CdSe/CdS Nanoheterostructures with Rod and Tetrapod Morphologies

et al. 2007

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We have demonstrated that seeded growth of nanocrystals offers a convenient way to design nanoheterostructures with complex shapes and morphologies by changing the crystalline structure of the seed. By using CdSe nanocrystals with wurtzite and zinc blende structure as seeds for growth of CdS nanorods, we synthesized CdSe/CdS heterostructures nanorods and nano-tetrapods, respectively. Both of these structures showed excellent luminescent properties, combining high photoluminescence efficiency (~80% and ~50% for nanorods and nano-tetrapods, correspondingly), giant extinction coefficients (~2·10 7 M -1 cm -1 and ~1.5·10 8 M -1 cm -1 at 350 nm for nanorods and nano-tetrapods, correspondingly) and efficient energy transfer from the CdS arms into the emitting CdSe core. † Current address:

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Colloidal nanocrystal synthesis and the organic–inorganic interface

Cited by 3,095 publications

References 65 publications

Nonaqueous Sol–Gel Routes to Metal Oxide Nanoparticles

Nonaqueous Sol–Gel Routes to Metal Oxide Nanoparticles

Faceting of Nanocrystals during Chemical Transformation: From Solid Silver Spheres to Hollow Gold Octahedra

Seeded Growth of Highly Luminescent CdSe/CdS Nanoheterostructures with Rod and Tetrapod Morphologies

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