Continuous Synthesis of Precision Gold Nanoparticles Using a Flow Reactor

Nanoparticle synthesis using flow chemistry has the potential to enhance the large-scale accessibility of precision-engineered nanomaterials at lower prices. This goal has been difficult to achieve primarily due to reactor fouling and the lack of efficient reagent mixing encountered, especially in those scaled-up systems. The present study aimed to overcome the two challenges by integrating a liquid-liquid biphasic segmented flow system with static mixing. This strategy was applied to the synthesis of gold nanoparticles (AuNPs) using citrate reduction chemistry. It was demonstrated that reactor fouling was eliminated by implementing the biphasic flow strategy. As a result, the overall mean particle size of the as-synthesized AuNPs was measured to be 15.5 nm with a polydispersity index (PDI) of 0.07, and with the reproducibility of ± 6.4 %. The biphasic flow system achieved a reaction yield of 88.7 ± 1.1 % reliably with a throughput of 60 mL/hour up to 8 hours.