In Situ Redox Microfluidic Synthesis of Core–Shell Nanoparticles and Their Long-Term Stability

An in situ redox process in microfluidic reactors was developed to synthesize hybrid nanoparticles with amorphous metallic cores and uniform metal oxide shells embedded with nanocrystallites at large scale. For example, the fabricated Fe(B)@iron oxides nanoparticles (NPs) exhibit permanent ferromagnetic properties at room temperature due to the strong magnetic coupling between different parts and the nanocrystalline pinning effect, providing an alternative design of nanostructures to break out the superparamagnetic limit in ultratiny particles. The NPs with amorphous metallic cores and uniform metal oxide shells can be well maintained over 4–5 months. The dictated novel microfluidic process provides a large-scale synthetic strategy for metal@metal oxide core–shell NPs with uniform shells and long-term stability and can be extended to a variety of material systems.