Shape-selective oriented cerium oxide nanocrystals permit assessment of the effect of the exposed facets on catalytic activity and oxygen storage capacity.

The catalytic performance of a range of nanocrystalline CeO2 samples, prepared to have different morphologies, was measured using two accepted indicators; oxygen storage and diesel soot combustion. The same powders were characterized in detail by HR-TEM, XRD, XPS, and Raman methods. The study demonstrates that activity is determined by the relative fraction of the active crystallographic planes, not by the specific surface area of the powders. The physical study is a step toward quantitative evaluation of the relative contribution to activity of the different facets. The synthetic protocol permits fabrication of CeO2 nanostructures with preferentially grown active planes, and therefore has potential in developing catalytic applications and in nanocompositing.

One-pot synthesis of ultra-small cerium oxide nanodots exhibiting multi-colored fluorescence.

CeO(2) nanodots of diameter 2nm have been synthesized by the thermolysis of cerium acetate in diphenylether in the presence of an oleic acid surfactant. The surfactant coating enabled them to be easily dispersible in nonpolar solvents. The CeO(2) dots exhibited size dependant optical properties such as a red shift in absorption and band gap. As a result, the surfactant coated CeO(2) nanocrystals emit photons in the visible region with broad photoluminescence spectra resulting in multi-colored fluorescence, which originates from defects associated with CeO(2) nanocrystals approaching molecular dimensions.