Research: Nanomaterials Synthesis

Chemically synthesized nano materials are being considered as the active elements in many applications, including photovoltaic, energy, displays, and bio-chem sensing. In order to realize the promise of these devices, it will be critical to have an efficient, reproducible synthesis technique of the nanostructures. Currently, nanoparticles are synthesized in a batch mode in small volumes, which is appropriate for studying the fundamental properties of nanosized structures and for developing proof of principle device structures. However, batch synthesis suffers from irreproducibility of size, size distribution, and quality of the nano-material from batch to batch. Moreover, there is inherent difficulty in scaling up to quantities more reasonable for device development and optimization.

Continuous flow reactors based on microfluidics (microreactors) integrated with heaters and fluid control elements offer a solution to these problems as well as additional advantages, including enhancement of mass and heat transfer, feedback control of temperature and feed streams, reproducibility, potential for sensor integration for in situ reaction monitoring, rapid screening of parameters, and low reagent consumption during optimization.

The small reaction volumes combined with the high heat and mass transfer rates enable reactions to be performed under more aggressive conditions with higher yields than can typically be achieved with conventional reactors. Moreover, new reaction pathways deemed too difficult to control in conventional macroscopic equipment can be conducted safely because of the high heat transfer and ease of confining small volume. This ability to work at elevated temperatures and pressures while confining potentially toxic, high reactive starting materials is particularly important for the synthesis of novel nanostructured materials. High pressure allows for wider range of chemistry, since at sufficiently high pressure, virtually any common solvent, precursor, and ligand will remain either liquid or become supercritical at the temperatures required for nanomaterials synthesis.

Areas of focus include:

  • II-VI and III-V quantum dot synthesis
  • compositionally graded nanostructures
  • metal and metal-oxide complexes for catalysis
  • complex oxides and zeolites