Green-mediated sol-gel fabrication of CuO/ZnO nanoparticles from orange peel extract for environmental remediation: insights from x-ray diffraction analysis using various models

Abstract This study introduces an eco-friendly and simple approach for synthesizing zinc oxide (ZnO), copper oxide (CuO), and ZnO-CuO composite nanoparticles using orange peel extract, minimizing the use of harmful chemicals while enhancing their antibacterial and photocatalytic properties. The nanoparticles were annealed at 400 °C for 2 h in the air. Characterization was conducted using x-ray Diffraction (XRD), Dynamic Light Scattering, Fourier Transform Infrared Spectroscopy (FTIR), and UV-visible Spectroscopy. XRD revealed that ZnO and CuO nanoparticles crystallized in hexagonal wurtzite and monoclinic structures, respectively, with crystallite size and lattice strain analyzed through Williamson–Hall, Size-Strain Plot, Halder-Wagner, and Wagner-Aqua methods. FTIR spectra confirmed the presence of Zn-O and CuO bonds, verifying successful synthesis. The optical bandgaps measured were 3.07 eV for ZnO, 2.702 eV for CuO, and 1.842 eV for the ZnO-CuO nanocomposite. Antimicrobial efficacy, assessed via the disc diffusion method, showed the ZnO-CuO composite exhibited enhanced antibacterial activity against both gram-positive and gram-negative strains compared to individual ZnO and CuO. Photocatalytic experiments demonstrated that under sunlight, the ZnO-CuO nanocomposite achieved 78% degradation of 10 ppm methylene blue within 90 min, outperforming individual ZnO (55%) and CuO (38%). These results highlight the ZnO-CuO composite’s potential for effective dye degradation and environmental remediation applications.