Facile Synthesis of Monodisperse Gold Nanocrystals …

In this study, we introduce the unique chemical phenomenon of highly shortened SWNTs that allows crafting monodisperse nanocrystals with well-defined size and shape. The simple reaction scheme involves CNTs and metal salts in water at ambient conditions with a step-wise change of metal ion concentration. The fundamental chemistry of our approach is same as that in our recent report (i.e., direct redox reaction between metal ions and nanotubes). Nonetheless, the current approach distinguishes itself by further tempering CNTs’ size and their dispersity in water to synthesize monodisperse single crystalline metal NPs with better control. Also the simplicity allows large-scale production. In this research, the CNTs’ exceptional capability is confirmed using chloroauric acid (HAuCl4) and SWNTs as model compounds. Also we report unique physicochemical features of the synthesized Au nanocrystals.

Facile Synthesis of Monodisperse Gold Nanocrystals Using ..

of Monodisperse Spherical Nanocrystals.

Synthesis and characterization of nearly monodisperse …

Ionic liquids are considered as organic solvents with high polarity and a pre-organized solvent structure. Crystalline NPs can be synthesized by using ionic liquid at ambient temperature []. Warner and coworkers have developed magnetic NPs coated with a group of uniform materials based on organic salts by using ion exchange water-in-oil (w/o) microemulsion approach []. These MNPs could potentially be applied in drug delivery, MRI and protein separations.

Journal of Nanoscience and Nanotechnology

Monodisperse gold nanocrystals with unique near-infrared optical properties were synthesized by simple mixing of highly shortened and well disperse single-walled carbon nanotubes and chloroauric acid in water at ambient conditions with a step-wise increase of gold ion concentration.

Synthesis and Characterization of Monodisperse Nanocrystals and Close-Packed ..
Rational design of the gram-scale synthesis of nearly monodisperse semiconductor nanocrystals SpringerLink

Surface modification, functionalization and …

In this contribution, we evaluate the potential of the DOE approach using the Taguchi method of experimental plans for the optimization of the synthesis of semiconductor nanocrystals []. We chose CdSe nanocrystals as a model system, taking advantage of the reported correlations between their size/size distribution and their optical properties [,]. The DOE method allowed us with a minimum number of experiments to deduce the degree of influence of each individual reaction parameter on the nanocrystals' mean size and size distribution and indicated interactions between the parameters. We present the results of the matrix cross-analysis of 16 experiments, which served as the basis for the subsequent determination of optimum synthesis parameters of three different-sized, nearly monodisperse samples of CdSe nanocrystals. Our study reveals that the DOE method is a useful tool for the rapid optimization of nanocrystal synthesis methods. On the other hand, we demonstrate its limits in terms of predictivity, which strongly depends on the initially defined experimental domain and on the interactions between experimental parameters. The developed synthetic protocol can easily be scaled up without sacrificing the narrow size distribution of the samples. This is shown in the second part of the article, where we describe the experimental setup and conditions for the gram-scale synthesis of CdSe core and of highly luminescent CdSe/CdS/ZnS core/shell/shell nanocrystals.

Facile synthesis of hollow Cu2O octahedral and spherical nanocrystals and their morphology-dependent photocatalytic properties N

Encyclopedia of Chemical Processing and Design

Experimental setup. (a) Experimental setup used for the gram-scale synthesis of nearly monodisperse CdSe nanocrystals. (b) CdSe/CdS/ZnS core/shell/shell nanocrystals in the 2-L reactor at the final stage of synthesis. (c) Purification using a glass filter column retaining the precipitated nanocrystals, while the solvent and byproducts are collected in the round-bottom flask below.

Rational design of the gram-scale synthesis of nearly monodisperse semiconductor nanocrystals Nanoscale Research Letters Full Te

The term surfactant is a blend of surface active agent

In order to improve the stability against photobleaching and the quantum yield of the obtained CdSe nanocrystals, their surface was subsequently passivated with a CdS/ZnS double shell. The intermediate CdS shell serves as "lattice mismatch mediator", reducing the strain between the CdSe core and the ZnS outer shell [,]. The same reactor was used as in the core nanocrystal synthesis, while a syringe pump replaced the peristaltic pump for the slow injection of the shell precursors. The latter were composed of a mixture of cadmium ethylxanthate and cadmium stearate for the CdS shell and of zinc ethylxanthate/zinc stearate for the ZnS shell, respectively []. During the shell growth, a red shift of the absorption (from 556 to 582 nm) and PL (from 573 to 592 nm) peaks is observed, indicating the partial delocalization of the exciton in the shell (Figure or ). The PL FWHM increases from 32 to 37 nm during the shell growth, going along with the enlargement of the size dispersion from 7.5% to 10%. The fluorescence quantum yield (QY) of the obtained CdSe/CdS/ZnS nanocrystals accounts for 81%, i.e., shell growth led to an increase of the PL QY by a factor of 10. In contrast to the used rather spherical CdSe core nanocrystals, the core/shell/shell particles have a more facetted shape. On TEM images (Figure ), a size difference of 2.2 nm between the core and core/shell/shell nanocrystals has been determined corresponding to three to four shell monolayers. This size increase is expected in view of the quantity of the injected shell precursors (calculated for obtaining 1.3 CdS monolayers and 2.5 ZnS monolayers), indicating that essentially the whole amount of precursors has been deposited on the core nanocrystals.