CuO-ZnO heterometallic hollow spheres: Morphology and defect structure

The Cu-ZnO hollow spheres, where CuO nanocrystals were dispersed in the shell of ZnO nanoparticals, were synthesized by using highly uniform and monodispersed Cu-embedded carbon spheres as sacrificial templates via a simple route under hydrothermal conditions. The morphology and structure of the spheres were characterized by FTIR, XRD, SEM, TEM and N-2 adsorption-desorption. It was suggested that the OH and C=O groups in the surface of the Cu-embedded carbon spheres facilitated the adsorption of Zn2+ in the aqueous solution, giving rise to the final CuO-ZnO hollow structure after these Zn2+-adsorbed spheres were calcined in air. Moreover, the photoluminescence (PL) study showed that the as-prepared CuO-ZnO hollow spheres and the annealed counterpart exhibited strong and dramatically weakened emissions, respectively. This remarkably different photoluminescent behavior afforded the evidence regarding the oxygen vacancy defects in the CuO-ZnO hollow spheres. (C) 2011 Elsevier Inc. All rights reserved.