Comparison of sunlight-driven photocatalytic activity of eco-friendly synthesized ZnO/CuO, ZnO/NiO and NiO/CuO binary nanocomposites

This research investigates the green synthesis and characterization of three binary metal oxide nanocomposites: ZnO/CuO, ZnO/NiO, and NiO/CuO. An environmentally friendly approach using plant extracts as bioreductants enabled the synthesis of these materials at room temperature, minimizing environmental impact. The nanocomposites were successfully synthesized and detailed characterization using techniques such as XRD, SEM, TEM, and UV–Vis spectroscopy confirmed their distinct structural and optical features. The average crystallite sizes were 13.98 nm (ZnO/CuO), 18.28 nm (ZnO/NiO), and 20.58 nm (NiO/CuO), with corresponding optical band gaps of 2.48 eV, 2.59 eV, and 2.62 eV. The photocatalytic efficiency of these materials was evaluated for the degradation of methylene blue (MB) dye under sunlight, with the performance following the order ZnO/CuO > ZnO/NiO > NiO/CuO. The ZnO/CuO nanocomposite showed the highest activity, achieving 95.42 % MB degradation within the defined period. The superior performance is attributed to the formation of an efficient heterojunction that enhances charge carrier separation and minimizes electron-hole recombination. These findings underscore the significant potential of green-synthesized binary metal oxide nanocomposites as efficient and sustainable photocatalysts for addressing wastewater pollution.