Biosynthesis of CuO/ZnO Nanocomposites Using Leaf Extract of Croton Macrostachyus: Characterization, Photodegradation, and Biological Activities

CuO/ZnO nanocomposites were synthesized using Croton macrostachyus leaf extract by the solution combustion method. The purpose of this study was to synthesize, characterize ZnO, CuO nanoparticles and CuO/ZnO nanocomposites using Zn (CH₃OO) ₂.2H₂O and Cu (NO₃)₂.3H₂O as precursors. The synthesized samples were characterized via UV–visible spectroscopy, UV–visible diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy with energy dispersive X-ray and Transmission Electron Microscopy, High Resolution Transmission Electron Microscope and Selected Area Electron. As it was observed from powder X-ray diffraction, as the copper precursor concentration increased the size of the sample were decreased, 18.13 nm, and 8.30 nm for CuO/ZnO (1:4) and CuO/ZnO (1:1) nanocomposites, respectively. This cause the band gap energy decreases. The elemental composition of CuO/ZnO (1:1) nanocomposites was equal ratio to the weight of their precursor and the shape of spherical and rod like. The anti-bacterial activities of ZnO and CuO nanoparticles showed the highest inhibition zone for Staphylococcus aureus (S. aureus) (12.00 mm) and Salmonella typhi (S. typhi) (12.00 mm), respectively. For CuO/ZnO (1:1) nanocomposites, a significant inhibition zone was obtained for S. aureus (23.83 mm) and Escherichia coli (E. coli) (23.33 mm) which is greater than that of individual nanoparticles. In other bacterial strains, inhibition zone was moderate compared to the gentamicin inhibition zone (20 to 24.03 mm).The scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DDPH) for CuO and ZnO nanoparticles showed less than that of ascorbic acid,however CuO/ZnO nanocomposites displays better scavenging activity. CuO/ZnO nanocomposite is showed highest efficiency of methylene blue dye degradation (97.58%) upon irradiation of sunlight within 75 min.