Accelerated and simplified synthesis of magnetic mesoporous nanoparticles in a continuous multistep microfluidic system

Here a fully continuous flow strategy for the preparation of Fe₃O₄@nSiO₂@mSiO₂ nanocomposites starting from ferrous and ferric ions was established for the first time. The three synthetic steps for Fe₃O₄ core, nonporous silica middle shell and mesoporous silica outer shell were connected and integrated into a single flow sequence with a total residence time of approximately 3 min. Moreover, the multistep continuous flow system was simplified with smaller footprint and increased safety by feeding all the ammonia needed by the three synthetic steps only once at the starting point of the system. The final product Fe₃O₄@nSiO₂@mSiO₂ nanoparticles with a specific surface area 378 m² g⁻¹ and saturation magnetization 19.3 emu g⁻¹ showed great potential as a catalyst support with easy and excellent recyclability. Proved to be capable of achieving fast and accurate parameter optimization, the uninterrupted continuous flow system proposed in this work holds great prospects to mediate multistep synthesis of complex nanoparticles with hierarchical structures in an efficient and controllable manner.