Synthesis, characterization, and adsorption studies of nanocrystalline copper oxide and nickel oxide

Nanocrystals of CuO and NiO have been produced by an alkoxide-based synthesis involving the corresponding metal chlorides, ethanol, and water. The resulting oxides are in the form of powders, with the CuO having crystallites in the size range of 7-9 nm and the NiO having crystallites in the size range of 3-5 nm. These crystallites aggregate together to form larger spherical particles, which have been studied by transmission electron microscopy and Brunauer-Emmet-Teller methods and were found to contain many pores and tunnels. It is because of this that an uncharacteristically high surface area is found, averaging about 135 m(2)/g for CuO and 375 m(2)/g for NiO. As seen with other metal oxides, once they are made as nanoparticles their reactivity is greatly enhanced. This is thought to be due to morphological differences, whereas larger crystallites have only a small percentage of reactive sites on the surface, smaller crystallites will possess much higher surface concentration of such sites. Elemental analysis, X-ray diffraction, and infrared spectroscopy have been used to characterize this nanoparticles, and reactions with CCl4, SO2, and paraoxon have demonstrated significantly enhanced reactivity and/or capacity compared with common commercial forms of the oxide powders.