Continuous Production of Monodisperse Silver Nanoparticles Suitable for Catalysis in a Droplet-Based Microreactor System

Silver nanoparticles (Ag NPs) with sizes below 50 nm have high value in catalysis, especially in electrocatalysis. However, due to the low efficiency of mass and heat transfer, conventional batch synthesis is unable to produce high-quality Ag NPs repeatedly at a large scale. To tackle this obstacle, a droplet-based microreactor system was designed in this work. Continuous and controllable synthesis of Ag NPs with sizes ranging from 7 to 30 nm, polydispersity indexes less than 10%, and high stability which could be stored at room temperature for 2.5 months were achieved by regulating residence time and introducing seed-mediated growth. Based on the Lifshitz-Slyozov-Wagner model and experimental data, growth kinetics were analyzed and revealed it as a diffusion-limited reaction, providing more powerful theoretical support for the synthesis of metal nanomaterials by the microreactor system.

Automated summary

A droplet-based microreactor system was designed to overcome the low efficiency of mass and heat transfer in conventional batch synthesis of Ag NPs. By regulating residence time and introducing seed-mediated growth, continuous and controllable synthesis of Ag NPs with sizes ranging from 7 to 30 nm, polydispersity indexes less than 10%, and high stability were achieved. This system provides a diffusion-limited reaction model for the synthesis of metal nanomaterials.