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Hollow Nanocrystals and Nanoreactors

IB-2012, 2018

APPLICATIONS OF TECHNOLOGY:

     
   
  TEM images of the synthesis of CoO hollow nanocrystals over time using the Berkeley Lab method.  
     
  • Catalysis
  • Drug delivery
  • Nano-optics
  • Nanoelectronics
  • Energy storage
  • Impact resistant materials


ADVANTAGES:

  • Very high surface to volume ratio
  • Uses an inexpensive, scalable chemical process with no sacrificial templates
  • Tunable shape, size, crystallinity, and void/shell ratios
  • Minimizes secondary reactions of products during catalysis
  • Maximizes synergistic catalyst-support interactions
  • Exterior and interior can be functionalized for selectivity
  • Particles can be magnetic for targeted drug delivery

ABSTRACT:

Paul Alivisatos and colleagues at Berkeley Lab have developed a new one-pot method for creating hollow nanocrystals.  The geometrically novel particles can be used for highly controlled catalysis and drug delivery, as well as optics, energy storage, and other nanoelectronic and advanced materials applications.  Using this scalable and inexpensive chemical process, the inventors have also succeeded in generating nanoreactors ­– hollow nanocrystals with a catalyst fixed within the inner pore – which demonstrate catalytic activity.

Berkeley Lab researchers take advantage of large differences in diffusion rates of select components to create the hollow nanocrystals and nanoreactors.  Reaction temperature, concentrations, and starting materials can be varied in this single pot process to generate uniform products of various shapes, sizes, porosities, and void/shell ratios.  The nanoshells display channels at the diffusion barriers that can be enhanced or diminished, decorated or functionalized, to allow selective access to the core region.

The Berkeley Lab hollow nanocrystals and nanoreactors have several advantages over conventional porous materials used in catalysis.  The method is less expensive and simpler than techniques that use sacrificial templates to create hollow particles; the surface to volume ratio is high; catalyst particles are separated by shells to prevent their aggregation; selective entry into the catalysis chamber of the nanoreactor greatly reduces the likelihood of desired products undergoing secondary reactions; and since each catalytic particle is fixed to a shell, synergistic catalyst-support interactions become more useful.

The variety of materials that can be used to create the crystals, their extremely small size, ease of preparation, and unique physical properties also offer advantages for energy storage, nanoscale optical and electronic devices, and impact resistant materials.  Magnetic hollow nanocrystals show promise for highly targeted drug delivery using magnetic fields.

STATUS:

  • Issued U. S. Patents 7,875,351 and 7,972,437 available at www.uspto.gov. Available for licensing.

FOR MORE INFORMATION:

Yin, Y., Rioux, R.M. , Erdonmez, C. K., Hughes, S., Somorjai, G.A., Alivisatos, A. P., “Formation of Hollow Nanocrystals Through the Nanoscale Kirkendall Effect,” Science 2004, 304, 711-14.

REFERENCE NUMBERS: IB-2012, IB-2018

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