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 N2 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.