Green Synthesis\nof a CuO–ZnO Nanocomposite\nfor Efficient Photodegradation of Methylene Blue and Reduction of\n4‑Nitrophenol

Abstract

CuO–ZnO nanocomposites (NCs) were synthesized\nusing an aqueous\nextract of Verbascum sinaiticum Benth.\n(GH) plant. X-ray diffraction (XRD), spectroscopic, and microscopic\nmethods were used to explore the crystallinity, optical properties,\nmorphology, and other features of the CuO–ZnO samples. Furthermore,\ncatalytic performances were investigated for methylene blue (MB) degradation\nand 4-nitrophenol (4-NP) reduction. According to the results, CuO–ZnO\nNCs with 20 wt % CuO showed enhanced photocatalytic activity against\nMB dye with a 0.017 min^–1 rate constant compared\nto 0.0027 min^–1 for ZnO nanoparticles (NPs). Similarly,\na ratio constant of 5.925 min^–1 g^–1 4-NP reductions was achieved with CuO–ZnO NCs. The results\nsignified enhanced performance of CuO–ZnO NCs relative to ZnO\nNPs. The enhancement could be due to the synergy between ZnO and CuO,\nresulting in improved absorption of visible light and reduced electron–hole\n(e^–/h⁺) recombination rate. In addition,\nvariations in the CuO content affected the performance of the CuO–ZnO\nNCs. Thus, the CuO–ZnO NCs prepared using V.\nsinaiticum Benth. extract could make the material\na desirable catalyst for the elimination of organic pollutants.