Emerging strategies for the synthesis of highly monodisperse colloidal nanostructures

Abstract

This short perspective describes recent developments in the synthesis of nanoscale colloids from sparingly soluble precursors. These strategies, which we dubbed 'heterogeneous nanocrystal syntheses' owing to the presence of a precursor in a non-colloidal solid state, have demonstrated the ability to generate new colloidal shapes, a superior monodispersity and a remarkable ability to delay the onset of Ostwald ripening, when compared with more traditional and purely colloidal strategies. We review the key contributions to this emerging area of research and discuss in detail the remarkable number of differences between these syntheses and the widely used homogeneous organometallic syntheses for making nanoscale colloids.

Sustainable scalable synthesis of sulfide nanocrystals at low cost with an ionic liquid sulfur precursor

“…In the case of heterogeneous reactions, i.e., where the majority of the metal precursor is present as a solid 23 , recycling of the unreacted metal precursor is even simpler: excess precursor is recovered by centrifugation and reused. PbS nanocrystals with low polydispersity (3.9 ± 0.3 nm) were synthesized in high sulfur yields (~68%) by reacting a slurry of PbCl 2 in OLA with OLAHS (Fig.…”

“…Efforts to find sustainable approaches to nanoparticle synthesis (mostly oxides and metals, rarely other compositions 11 , 16 , 17 ) have focused on finding renewable feedstocks 2 , 16 – 21 . Other green chemistry principles, such as reducing waste, recycling, improving yield and atom economy, and minimizing auxiliaries and reaction steps have rarely been addressed 13 , 22 , 23 .…”

Contamination-free solutions of selenium in amines for nanoparticle synthesis

“…Soluble selenium in ethylenediamine 14 is limited by the low boiling point temperature of the solvent and general poor solubility. Oleylamine (OLA) used alone can only dissolve small quantities of selenium 4,6,7,22 and only at higher temperatures due to the relatively weak reducing ability of amines. 23 This can be overcome if the amines are coupled with a reducing agent like the alkali borohydrides, 16,24,25 however this then introduces boron and alkali ion contaminants to the system altering growth mechanisms 26 as well as electronic properties.…”

“…Herein we report a new route to create a solution of dissolved selenium, with a high concentration, possessing the flexibility of a wide range of boiling points. This specific method was designed for the formation of pure selenide nanomaterials, due to the need for a homogeneous solution 8,11,22,27 to reproducibly generate nanoparticles with a controlled size. Although developed for this application, the flexibility of the approach enables possible tailor-made routes for other applications.…”

Synthesis of layered platelets by self-assembly of rhenium-based clusters directed by long-chain amines

“…The use of amphiphilic molecules presents several advantages due to their ability to direct or template the growth of nanostructures, 29 since the polar functional group of the amphiphile tends to interact with the growing structure while the non-polar tails interact with each other outward. 23,30 This results in the stabilisation of the final structure, avoiding agglomeration and simplifying the further processing, besides that in some cases the amphiphilic molecules also become part of the structure, acting as a scaffold.…”