Jump to main content
Jump to site search

Issue 10, 2012
Previous Article Next Article

Controlling bubbles using bubbles—microfluidic synthesis of ultra-small gold nanocrystals with gas-evolving reducing agents

Author affiliations

Abstract

Microfluidic wet-chemical synthesis of nanoparticles is a growing area of research in chemical microfluidics, enabling the development of continuous manufacturing processes that overcome the drawbacks of conventional batch-based synthesis methods. The synthesis of ultra-small (<5 nm) metallic nanocrystals is an interesting area with many applications in diverse fields, but is typically very challenging to accomplish in a microfluidics-based system due to the use of a strong gas-evolving reducing agent, aqueous sodium borohydride (NaBH4), which causes uncontrolled out-gassing and bubble formation, flow disruption and ultimately reactor failure. Here we present a simple method, rooted in the concepts of multiphase mass transfer that completely overcomes this challenge—we simply inject a stream of inert gas bubbles into our channels that essentially capture the evolving gas from the reactive aqueous solution, thereby preventing aqueous dissolved gas concentration from reaching the solubility threshold for bubble nucleation. We present a simple model for coupled mass transfer and chemical reaction that adequately captures device behaviour. We demonstrate the applicability of our method by synthesizing ultra-small gold nanocrystals (<5 nm); the quality of nanocrystals thus synthesized is further demonstrated by their use in an off-chip synthesis of high-quality gold nanorods. This is a general approach that can be extended to a variety of metallic nanomaterials.

Graphical abstract: Controlling bubbles using bubbles—microfluidic synthesis of ultra-small gold nanocrystals with gas-evolving reducing agents

Back to tab navigation

Supplementary files

Article information


Submitted
03 Dec 2011
Accepted
27 Feb 2012
First published
06 Mar 2012

Lab Chip, 2012,12, 1807-1812
Article type
Paper

Controlling bubbles using bubbles—microfluidic synthesis of ultra-small gold nanocrystals with gas-evolving reducing agents

S. A. Khan and S. Duraiswamy, Lab Chip, 2012, 12, 1807
DOI: 10.1039/C2LC21198J

Social activity

Search articles by author

Spotlight

Advertisements