Sustainable photocatalytic approach: Natural sunlight-driven Degradation of β-naphthol by solution-Free CeO2-ZnO nanocomposite

This work explores the fabrication and analysis of CeO 2 -ZnO nanocomposites (CZ NCs) using a simple, economical, and solution-free method for preparation, promoting sustainable chemistry by eliminating solvents, reducing waste, and minimizing environmental impact. X-ray diffraction (XRD) analysis of CZ NCs revealed a decrease in crystallite sizes with an increase in Ce (IV) ion concentration. Field Emission Scanning Electron Microscope (FE-SEM) observation indicated that modification of Zinc Oxide nanoparticles (ZnO NPs) with the incorporation of Ce (IV) ions results in the formation of cuboidal structures. The polycrystallinity of the material was confirmed by High-Resolution Transmission Electron Microscopy (HRTEM). The Diffused Reflectance Spectrum (DRS) analysis of 5 wt% (or 05:95 for CeO 2 :ZnO) CZ NCs resulted in a narrowing of the band gap from 3.15 eV to 3.04 eV. The surface area analysis revealed an increase from 30.86 m²/g for ZnO NPs to 48.91 m²/g for 5 wt% CZ NCs. Under natural sunlight, 5 wt% CZ NCs exhibited remarkable photocatalytic performance, breaking down 91% of β-naphthol in an aqueous solution within just 20 min at a 0.8 mg/mL concentration. Scavenger tests confirmed hydroxyl radicals (⋅OH) as key contributors to pollutant degradation. The reusability assessment of CZ NCs demonstrated their stability across three successive cycles. The disc diffusion assay was employed to assess the activity of antibacterial targeting Staphylococcus aureus MTCC 737 , revealing that 5 wt% CZ NCs exhibited enhanced antibacterial efficacy compared to ZnO NPs. The present approach helps to achieve cleaner water and reduced microbial contamination, supporting sustainable environmental remediation.