Nanocrystals or nanoparticles continue to evolve in technological relevance, with application in fields as diverse as energy (solar energy harvesting), environment (safer municipal water treatment), medicine (tumor diagnostics and treatments) and microelectronics (mobile devices and memory). These small particles, ranging in size from a few nanometers to almost a micron, serve many purposes, and in most cases it is their small size that yields unique material properties and functionality that are unattainable with the same material with a larger size. These properties promise extensive market potential and corresponding societal impact should scalable manufacturing processes be put into place that can provide large quantities of material at low cost with high quality, all the while limiting the environmental impact of their production. This award supports fundamental studies to provide a versatile manufacturing platform for the continuous production of high quality nanocrystals. Such a platform will permit economically-attractive and distributed, rather than centralized, production that can be utilized for on-demand applications, similar to the promise of 3D printing. The ability to produce customized nanocrystals in a rapid, cost effective fashion, as is possible with a membrane reactor concept, can be a significant advance in the evolving 21st century U.S. manufacturing infrastructure.
The routine production of well-defined nanoparticles remains a significant challenge, because of the interplay between equilibrium constraints and rate-based reaction and mass transfer processes. Typically, a trade-off exists between the achievable product quantity and quality, with higher production rates resulting in diminished control of nanocrystals' size, morphology, uniformity and the associated material properties. To address this ongoing challenge, the team will use experimentation, modeling, in-depth materials characterization, and creative system design, to confront the significant scientific and engineering questions with respect to the coupling of the membrane's geometric degrees-of-freedom to the hydrodynamic aspects of a flow system, and the specific chemical reactions, in order to synthesize nanocrystals with desirable material properties. New phenomena may also be uncovered related to how the nanometer size of the "surface reaction domains" on the membrane's porous surface can further affect how the critical stoichiometry for a reaction (or other phase transition) is reached and exceeded. The feasibility and scalability of this manufacturing innovation will be demonstrated through the manufacture of magnetite, silver, gold, and halogen-stabilized chalcogenide nanocrystals, all regarded as technologically significant nanomaterials that are beginning to impact a number of key industries.
