Scaling up the production of colloidal nanocrystals: should we increase or decrease the reaction volume?

Recent progress in facet-controlled syntheses has started to produce nanocrystals with great promise as the next-generation catalysts for a variety of applications. To move from academic studies to industrial applications, however, one has to address the issue of scaling up a synthesis that has been commonly conducted in a batch format. There are two opposite approaches to scaling up the production of colloidal nanocrystals: increasing and decreasing the reaction volume. Contrary to conventional wisdom, continuous flow synthesis based on droplets is expected to provide a more practical platform for scaling up the synthesis. Here we highlight recent progress in using droplet reactors for the synthesis of colloidal noble-metal nanocrystals with controlled sizes and shapes, with an aim towards high-volume production.