Synthesis of Functional Nanoparticles Using a Microreactor

Fine particles are widely used as intermediate and final products in industrial processes. Because particle properties are directly linked to the function and quality of the products, synthesizing monodispersed particles is a key technology. A microreactor, which comprises microchannels typically narrower than 1 mm, is a promising reaction tool because it offers excellent mixing and heat transfer performance. We used a microreactor for the synthesis of single-component and composite nanoparticles. This review introduces our synthetic results for functional nanoparticles including nickel, platinum–cobalt alloys, gold and silver nanoshells, patchy particles, core–shell clusters, and metal–organic frameworks. The microreactor we used is of the central-collision type and exhibits a characteristic mixing time 100~1,000 times shorter than that of the conventional batch mixing. The excellent mixing ability of the microreactor enables the synthesis of monodisperse particles in size and shape as well as core–shell particles with uniform shell thickness through instantaneous nucleation. More importantly, the microreactor realizes syntheses, which are not possible with batch reactors, by trapping reaction intermediates in a sequential reaction process and by rapidly changing the reaction temperature. These results demonstrate great advantages of using the microreactor for nanoparticle synthesis.