Continuous Synthesis of Monodisperse Ag Nanocubes

Abstract

The precise control of both the size and shape of Ag nanoparticles strongly influences their optical properties. Although the synthesis of Ag nanocubes with sharp corners and edges has been demonstrated, the ability to scale these approaches with high selectivity remains elusive. In this study, a continuous flow microwave-assisted reactor was used to separate nucleation from growth events, which provides a method to synthesize very uniform single crystalline Ag nanocubes. Nucleation in the microwave zone was enhanced through seed-mediated processes by sulfide formation, and a chemical regulator was used in the growth zone to further improve the sharpness of the edges of the nanocubes. Transmission electron microscopy and optical properties were used to optimize the reaction conditions and Ag nanocubes with edge lengths of 28 and 45 nm were readily synthesized with narrow particle size distributions and high selectivities (>70%). Nanocubes with 28 nm edge lengths were used to prepare films to demonstrate the detection of Rhodamine 6G with concentrations down to 10 nM using surface enhanced Raman spectroscopy. These results indicate that continuous flow approaches have the potential to produce large quantities of uniform Ag nanocubes that can be used for sensing or other applications.

Effects of process parameters on Cu‐nanoparticle synthesis in tetraethylene glycol through microwave irradiation

“…We propose a simple and fast process without any addition of reducing agent by utilising only the reducing characteristic of polyol to synthesise Cu nanoparticles using a low‐cost CuO precursor. The short synthesis time of 3 min indicates that microwave‐assisted Cu synthesis is a method applicable to a continuous flow microwave‐assisted reactor for industrial production [41]. The non‐aggregated Cu particles smaller than 100 nm can be applicable as a low‐cost filler material for the fabrication of electrode or conduction patterns by intense pulsed light sintering [42–44] as well as sinter chip‐bonding [31–33].…”

Screening Small Metabolites from Cells as Multifunctional Coatings Simultaneously Improves Nanomaterial Biocompatibility and Functionality

“…Although nAg‐sorbitol and nAg‐cysteine showed comparable biochemistry, d ‐sorbitol enhanced the dispersity of nAg more strongly, and maintained the native shape of nAg better than l ‐cysteine, as shown by the results and discussion above. The high dispersity and the native shape of nAg are critical to its applications . Collectively, the coating of d ‐sorbitol could reduce the nanotoxicity of nAg and simultaneously maintain or even improve its intended effects, as confirmed below.…”

Continuous Flow Routes toward Designer Metal Nanocatalysts

“…There has been an effort to separate nucleation events from growth events during NP synthesis by sequentially utilizing an RF heating unit and a temperature‐controlled oil bath unit . Figure 6 shows a scheme of this multistep reactor using both heating components as well as a TEM image of the Ag nanocubes synthesized in the microreactor . Initially, the reagents flowed through the microwave zone to synthesize spherical Ag NPs.…”

“…This figure also includes a transmission electron microscopy image of the Ag nanocubes synthesized in the microreactor. Adapted with permission . Copyright 2017, American Chemical Society.…”

“…Microreactors have been typically limited to one synthesis inline, which could limit the continuous‐flow production of many shape and architecturally controlled NPs as they are traditionally produced by sequential batch processes wherein NP seeds are produced first. However, multistep microreactors for NP synthesis are appearing like the microwave and oil bath example that separates nucleation and growth processes . Furthermore, these microreactors can be broken down into two complete growth segments for an initial seed growth followed by overgrowth of a secondary metal.…”