RSC Publishing


Publishing

 

Cover image for Highlights in Chemical Science

Highlights in Chemical Science

News from across RSC Publishing.



Zooming in on nanoparticles' defects


19 March 2008

US researchers have found a way to study defects on surfaces of nanoparticles, which are thought to be critical for catalytic activity.

Metal nanoparticles are the key to the activity of many catalysts, including those in car catalytic converters. To improve these catalysts it is important to know what is happening at the atomic level. Miguel José-Yacamán and colleagues at the University of Texas at Austin have found that, using microscopy and computer modelling, they can obtain much more detail than before about nanoparticle surface defects.

TEM image of 3 spherical layers of crystal
Gold–palladium nanoparticles show defects on their surface
José-Yacamán's method uses aberration-corrected TEM (transmission electron microscopy), which uses software to correct distortions introduced by the microscope lenses. This enables imaging of atoms in non-regular environments (such as at surface defects), which is not possible with regular TEM. The team applied this technique to a gold-palladium nanoparticle, and not only found that it was a single crystal, but that it consisted of three distinct spherical layers, each with a different ratio of the two metals. They also obtained electron density profiles along different axes through the particle. By comparing these with computer models, they found that the nanoparticle contains steps, edges and kinks on its surface.

José-Yacamán says their results show that 'the surface of the particle is rather rough at the atomic scale.' He adds that it is very likely that the stepped surface of these nanoparticles plays an important role in their catalytic activity.

David Cockayne, professor of materials chemistry at the University of Oxford, UK, is enthusiastic about the work, saying that it 'demonstrates the enormous potential for modern aberration-corrected TEM to explore the complex and technologically important structures of nanoparticles.' Luis Liz-Marzàn, an expert in nanoparticles from the University of Vigo in Spain, echoed these thoughts, saying this 'represents a leap in electron microscopy capabilities for nanoparticle analysis.'

David Barden

Link to journal article

Atomic structure of three-layer Au/Pd nanoparticles revealed by aberration-corrected scanning transmission electron microscopy
Domingo Ferrer, Douglas A. Blom, Lawrence F. Allard, Sergio Mejía, Eduardo Pérez-Tijerina and Miguel José-Yacamán, J. Mater. Chem., 2008, 18, 2442
DOI: 10.1039/b801320a

Also of interest

Nanocharacterisation

Nanocharacterisation

Copyright: 2007
Angus Kirkland

Nanocharacterisation is a rapidly developing field. Contributions in this book from across the globe provide an overview of the different microscopic techniques for the characterisation of nanostructures.


Window into nanospace could boost batteries

Investigating how nickel hydroxide crystals grow in nanospace could lead to improved performance of rechargeable batteries, say scientists in Japan.

Pushing the boundaries of nanoparticle detection

Smaller than ever nanoparticles can be studied using new microscopy methods.

Computer-aided nanoparticle synthesis

Fed up with having to optimise your own reactions? Ever wondered why you can't get a computer to do it for you?