Fundamental chemistry at the nanoscale: new insights revealed in our recent ACS Nano paper on colloidal ceria nanoparticles

Thanks to an ongoing collaboration between our group and the group of Prof. Pieter Glatzel at the European Synchrotron Radiation Facility (ESFR), new insights on the fundamental behavior of nanoparticles have been revealed. The work, carried out on our side by Dr. Eduald Casals and Prof. Víctor Puntes, shows that colloidal Ceria nanoparticles of 3nm and 10nm have a delocalized charge distribution with a behavior that is rather in the quantum regime – invoking the picture of a “(nano-sized) electron sponge”.

To achieve these results it was necessary to perform “in situ” high-energy experiments, that is, directly observing the formation and evolution of the nanoparticles with high-energy resolution fluorescence-detected hard X-ray absorption spectroscopy (HERFD-XAS), occurring in real time at the ESRF beam line. The study also points out the relevance of the medium in which nanoparticles are immersed, since other previous works performed in high vacuum do not properly reproduce their chemical activity.

Overall, these results indicate that nanoparticles’ chemical activity is closer to that of molecules rather than to the bulk material, highlighting (once again) the complexity of physicochemical behavior of nanostructures. A deeper understanding of these phenomena is a sure prerequisite for analyzing and predicting the biological and toxicological of nanoparticles, particularly for Ceria and others which find multiple applications in energy, medicine and consumer products.

See also press release from ESRF: http://www.esrf.eu/home/news/general/content-news/general/Nano%20sponge.html

Cafun, J.-D., Kvashnina, K. O., Casals, E., Puntes, V. F., & Glatzel, P. Absence of Ce3+ Sites in Chemically Active Colloidal Ceria Nanoparticles. ACS Nano, ACS Nano, 2013, 7 (12), pp 10726–10732.

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