Preparation of Cu-Zn/ZnO core-shell nanocomposite by surface modification and precipitation process in aqueous solution and its photoluminescence properties

A novel core-shell structure material, Cu-Zn/ZnO, was prepared by a surface modification precipitation process in aqueous solution at low temperature. A nucleation and crystal growth model for this structure was proposed. The resultant nanocomposites were characterized by X-ray diffraction, transmission electron microscope, field emission scanning electron microscope and photoluminescence spectroscope. Results showed that 20-50 nm thick ZnO shell was obtained on the surface of Cu-Zn nanopowders directly in the aqueous solution at 40 °C during the precipitation process and as-synthesized materials have a strong ultraviolet luminescence peak around 379-390 nm, but no usual defect-related emissions in visible range. The quantum confinement effect of ZnO nanocrystals, the presence of Cu and Zn atoms and absence of defects in ZnO layer are believed responsible for the characteristics of the photoluminescence spectra.