Search

A novel CaNb2O6hierarchical micronanostructure was successfully fabricated under mild hydrothermal conditions in the absence of templates or organic additives. In this hierarchical micronanostructure, the nanosheets grow vertically on the surface of the onedimensional microneedles whose axial direction is along the caxis, and the single crystalline nanosheets are parallel to the 020 planes. A twostep nucleation–growth mechanism is proposed to explain the formation of the CaNb2O6hierarchical micronanostructure, based on the observation of a timedependent morphology evolution process. The hierarchically structured CaNb2O6exhibits a stronger enhancement of photocatalytic activity in the degradation of rhodamine B RhB than other morphological CaNb2O6samples, such as nanoparticles, nanoribbons, and microneedles. This simple hydrothermal method provides a new general approach for the synthesis of potentially useful niobates.

Cuprous oxide hollow nanospheres were prepared by heating a solution of copper acetate and hydrazine as a reductant in 2-propanol at reflux. The size distribution of the nanospheres is mainly in the range 100–200 nm. The products were characterized by X-ray diffraction, UV/Vis diffuse reflectance spectroscopy, SEM, and TEM. The results indicated that the Cu2O hollow nanospheres aggregated from small nanoparticles with an average size of ca. 6.6 nm. The UV/Vis diffuse reflectance spectrum indicated that the optical absorption edge of the hollow Cu2O nanospheres is redshifted relative to their solid counterparts. The influence of the reaction conditions, such as reaction temperature, reaction time, and the amount of water, on the formation of the nanospheres as well as their morphology were studied. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)