Synergetic green synthesis of CuO, ZnO, and CuO-ZnO nanocomposite nanoparticles using Genista hispanica L. extract for enhanced photocatalytic and antioxidant properties

In this study, CuO, ZnO, and CuO-doped ZnO (CuO-ZnO) nanocomposite nanoparticles were synthesized using a green approach, with Genista hispanica L. extract as a capping and reducing agent. The effects of extract concentration and calcination on the nanoparticle’s (NPs) morphological, structural, and optical properties were analyzed. The nanoparticles were characterized by UV–Visible (UV‒Vis), Fourier Transform Infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and zeta potential (ZP) measurements. X-ray diffraction confirmed monoclinic and hexagonal structures, with average sizes of 11.1, 13.0, and 8.8 nm after calcination for CuO, ZnO, and CuO-ZnO nanocomposite nanoparticles at 30 g of extract. SEM images showed reduced particle sizes (10.5, 8.7, and 8.4 nm) with increased extract concentration and calcination. The CuO-ZnO nanocomposite (NCs) demonstrated enhanced stability with a zeta potential of −12.23 mV. At the same time, CuO and ZnO nanoparticles exhibit a stability of −17.5 mV and −7.5 mV, respectively. Photocatalytic degradation of Methylene Blue (MB) revealed a maximum photodegradation rate of 38%, 27% for CuO and ZnO nanoparticles, and 87% for CuO-ZnO nanocomposite in 120 min, attributed to their synergistic effect. Antioxidant tests confirmed the superior scavenging activity of CuO-ZnO nanocomposites compared to individual oxides. Higher extract concentrations enhanced phytochemical content, resulting in smaller nanoparticles, while calcination improved purity. These results demonstrate the potential of CuO-ZnO nanocomposites for photocatalytic and antioxidant applications.