Low-cost preparation and characterization of new CuO/ZnO and Cu3N/ZnO nanocomposites

CuO/ZnO and Cu₃N/ZnO nanocomposites were prepared in a three-step synthesis consisting of the co-precipitation of Cu²⁺ and Zn²⁺ hydroxide carbonates (Cu/Zn-Carb) followed by their thermal treatment first in air and second in gaseous ammonia. The morphology and phase composition of the hydroxide carbonates were determined by the Cu:Zn molar ratio and the presence of polyvinylpyrrolidone (PVP) acting as a capping agent, respectively. The Cu/Zn-carbonates could be annealed in the air at 550 °C either as powders or as thin films. The latter were deposited on a silicon substrate using a choice of spin- or dip-coating techniques. The resulting CuO/ZnO samples were heated under gaseous ammonia at 300 °C in the final step of the process to form Cu₃N/ZnO nanocomposites. The fabricated samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) with energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric − differential thermal analysis (TG-DTA) and infrared spectroscopy (IR). SEM and XRD analysis indicates that the average diameter of spherical particles was about 130 nm (CuO/ZnO) and 100 nm (Cu₃N/ZnO), composed of crystallites with 10–20 nm sizes. The thermal treatment under air and NH₃ did not affect the morphology of the composites. The implication is, therefore, that the shape and size of CuO/ZnO oxide and Cu₃N/ZnO nitride/oxide composite nanostructures are determined at the point of hydroxide carbonate coprecipitation and can be controlled during precursor synthesis. This has significant ramifications for the reproducible fabrication of nanocomposite films of precise stoichiometry and bespoke morphology.