CuO:ZnO nanocomposite photocatalyst with tunable ratios of CuO was synthesized using a low-temperature-assisted co-precipitation method, which is suitable for industrial-scale production. Analytical techniques, including XRD, FE-SEM, HR-TEM, FTIR, XPS and UV–Vis, were utilized to investigate the structure, morphological characteristics, chemical composition and optical properties of the CuO:ZnO nanocomposite. The XRD analysis reveals that the samples exhibit a single phase, characterized by a wurtzite hexagonal structure of ZnO and a monoclinic structure of CuO. The average crystal size changed from [Formula: see text][Formula: see text]nm to [Formula: see text][Formula: see text]nm when CuO varied from 0% to 5% in the CuO:ZnO nanocomposite. The scanning electron microscope (SEM) images reveal that the nanocomposite particles exhibit a high degree of uniformity, with an average size of approximately 50[Formula: see text]nm. HR-TEM shows the width of lattice plane families consistent with X-ray diffraction for CuO and ZnO materials. The ZnO exhibits a unique hexagonal shape. Furthermore, there is a slight correlation between the CuO fraction and an increase in grain size. FTIR analysis revealed the specific vibrational modes of ZnO and CuO at wavenumbers of 564, 619, 651, 673 and 488, 607[Formula: see text][Formula: see text], respectively. XPS shows secondary valences of Cu and Zn indicating the formation of CuO and ZnO while the high Ov peak indicates the presence of Oxygen defects in the crystal lattice. The absorption results clearly demonstrate the presence of two absorption edges corresponding to ZnO and CuO, as well as the broadening of the absorption spectrum of the nanocomposite sample up to a wavelength of 840[Formula: see text]nm. The photocatalytic degradation of RhB yielded remarkable outcomes, as the concentration of RhB declined by 98.6% after 20[Formula: see text]min of illumination using a CuO:ZnO (3:97) nanocomposite. The photocatalytic efficiency is significantly influenced by changing the CuO ratio in CuO:ZnO nanocomposites. This can be attributed to the tradeoff between the effectiveness of the heterogeneous contact layer and the limited ability of CuO to catalyze photochemical reactions. Based on the scavenger test, hydroxyl and superoxide radicals are primarily responsible for the decolorization of RhB dye. Results of evaluating the reusability and stability of the material show that, after fifth recycling, the decomposition efficiency still reaches over 90% after 30[Formula: see text]min of illumination.
