Biosynthesis of ZnO/Ag nanocomposites heterostructure for efficient photocatalytic degradation of antibiotics and synthetic dyes

This study addresses the pressing issue of environmental pollution caused by antibiotics and synthetic dyes in aquatic ecosystems, presenting a novel approach for their efficient photocatalytic degradation. Zinc oxide (ZnO)-based nanoscale photocatalysts, including ZnO nanoparticles (NPs) and ZnO/Ag nanocomposite heterostructure (NCH), were synthesized through an innovative and eco-friendly method utilizing an extract derived from discarded lemon peels as a biogenic reducing agent. The synthesized materials were extensively characterized through UV spectrophotometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results confirmed the different morphologies of ZnO NPs and ZnO/Ag NCH, with average sizes of 20 nm and 42 nm, respectively. Notably, the ZnO NPs and ZnO/Ag NCH exhibited optical bandgap energies of 3.2 eV and 2.85 eV, respectively, signifying their potential as efficient photocatalysts. Under natural sunlight irradiation, these materials demonstrated exceptional photocatalytic activity, achieving a remarkable 98.8 % degradation rate for metronidazole and 90 % for ciprofloxacin in just 12 min. Furthermore, the ZnO NPs effectively removed 84 % of Toluidine Blue and 77 % of Congo red after 120 min, while ZnO/Ag NCH enhanced degradation rates to approximately 90.5 % for Toluidine Blue and 86 % for Congo Red. This research highlights the significant physicochemical properties and novel synthesis methods employed, positioning these sustainable nanomaterials as promising solutions for mitigating environmental pollution effectively.