Researchers at the National Institute of Standards and Technology (NIST) have done a mash-up of two very different experimental techniquesneutron scattering and electrochemical measurementsto enable them to observe structural changes in nanoparticles as they undergo an important type of chemical reaction. Their recently published technique* allows them to directly match up particle size, shape and agglomeration with the "redox" chemical properties of the particles. The measurements are important both for the design of nanoparticles for particular applications and for toxicology studies.
Nanoparticles present unique engineering challengesand opportunitiesbecause their extremely small size can give them physical properties quite unlike those they have in bulk quantities. The challenge for materials scientists is to determine just what those changes are and how they relate to particle size and structure.
The NIST team was interested in the oxidation-reductionredox properties of zinc oxide nanoparticles, which are used or being considered for a wide variety of applications ranging from sunscreens and antibacterial coatings to semiconductor and photoelectronic devices.
Redox reactions are one of the major divisions of chemical reactions, those that involve a transfer of electrons from one atom or molecule to another. Redox properties determine the path a chemical reaction will take. "They are the drivers of many biological processes," explains NIST materials researcher Vivek Prabhu. "There are many biochemical reactions that are well-defined oxidation-reduction reactions. There are tables of these. But there are no such tables that we know of on how nanoparticles can affect those reactions."
The NIST team knew they could monitor the size, shape and dispersion of nanoparticles in solution using SANSsmall-angle neutron scattering. The scattering patterns from a SANS instrument, says Prabhu, give you not only those details but st
|Contact: Michael Baum|
National Institute of Standards and Technology (NIST)