Microfluidic Multi‐Scale Homogeneous Mixing with Uniform Residence Time Distribution for Rapid Production of Various Metal Core–Shell Nanoparticles

Abstract

Seed‐mediated growth of core–shell nanoparticles, which is conventionally performed in a batch reactor, is successfully reproduced in a microfluidic reactor for a facile production of uniform metal core–shell nanoparticles. The proposed microfluidic design is based on the microstructure inversion for achieving multi‐scale homogeneous mixing with uniform nanoparticle residence time. Simulations demonstrate that among the staggered herringbone microstructures investigated in this study, the upper herringbone (UH) structure can rapidly and homogeneously mix multiple‐sized reagents and can also prevent both the irreversible trapping and long residence time of the nanoparticles inside the microfluidic channel. A wide variety of metal core–shell nanoparticles, namely Au@Ag, Au@Pd, and Au@Au with an interior nanogap, are synthesized by using the microfluidic reactor with built‐in UH microstructures. The proposed microfluidic synthesis produces a more uniform shell size than the conventional batch synthesis. This work could significantly expand the practical utility of metal core–shell nanoparticles in a multitude of applications ranging from catalysis to nanomedicine.

Advances in Microfluidic Synthesis of Solid Catalysts

“…The bimetallic particles often form alloys or core-shell structures and usually exhibit an excellent catalytic performance because of the synergistic effect of metal atoms [104]. For example, Au@Ag core-shell nanoparticles were synthesized (using HAuCl 4 and sodium citrate for the synthesis of Au core, and AgNO 3 and ascorbic acid for the preparation of Ag shell) in a single-phase microreactor (Figure 5a) and a conventional batch reactor, respectively [105]. Compared with the batch results, the spherical Au@Ag core-shell nanoparticles synthesized in the microreactor exhibited a more uniform shell size (Figure 5b,c) due to the faster mixing of reagents and better control over the reaction time.…”

Numerical investigation of multiscale lateral microstructures enhancing passive micromixing efficiency via secondary vortex flow

“…Current studies have shown that adding microstructures into microchannels to regulate the local flow field 29,30 can effectively provide a new technical solution for improving the passive mixing efficiency [31][32][33] at the microscale. This approach has been applied to the functional units of microfluidic systems as micromixers 34,35 and microreactors 36,37 . For example, a passive T-shape micromixer with rectangular winglets was developed against the flow direction.…”

Facile production of quercetin nanoparticles using 3D printed centrifugal flow reactors

“…For this reason, the RIAC is less suitable than other reported techniques for studying nanoparticle formation mechanisms or observing the transport of fluids and chemical species within microchannels. 47–51…”

“…For this reason, the RIAC is less suitable than other reported techniques for studying nanoparticle formation mechanisms or observing the transport of uids and chemical species within microchannels. [47][48][49][50][51] Building upon our previous study, in the present work we aimed to determine whether the RIAC can be employed as a tool for rapid, reliable and facile production of API nanocrystals. In particular, we report on the design and manufacturing of two different RIAC prototypes, the development of a method for API nanoparticle production using these devices, and a comparison of nanoparticles obtained through this method with those reported in the literature.…”