Dual jet-mixing reactor for fully continuous synthesis of core@shell Au@Ag nanocomposites†

The wide-scale production of nanomaterials would benefit from scalable synthetic methods. One class of promising nanomaterials consists of a core@shell structure in which one type of material is used for the core and a second material is grown on the surface to produce a shell. Although these materials are commonly realized in batch, core@shell structures have not yet been widely translated to scalable manufacturing processes. In this work, we investigate the continuous flow synthesis of Au@Ag core@shell nanomaterials using sequential jet-mixing reactors (JMRs). Connecting the two JMRs overcomes challenges with particle instability when the processes are separated. Using synthesis conditions typical for batch methods in the JMR resulted in a non-uniform particle size distribution. Through investigating the synthesis conditions of the Au core, the key parameters affecting the synthesis of well-defined nanoparticles are identified as the concentration of the reducing agent and the inclusion of bovine-serum albumin (BSA) to limit particle aggregation. The concentration of the reducing agent is adjusted to achieve a high yield of Au NPs. The adjusted concentration enabled continuous synthesis of Au@Ag core@shell nanoparticles using BSA as the stabilizing ligand in a dual jet mixing reactor system. Overall, this work provides insights on integrating sequential processes for the synthesis of core@shell nanomaterials.