Laurus nobilis-mediated fabrication of multifunctional ZrO2–ZnO nanostructures for wastewater remediation and biocidal applications

In this study, we synthesized ZnO–ZrO2 nanostructures using Laurus nobilis leaf extract. UV–Vis analysis showed peak absorbance at 293 nm for ZnO, 280 nm for ZrO2, and 281.6 nm for ZrO2/ZnO, with corresponding band gaps of 3.29 eV, 3.987 eV, and 3.8 eV. BET results indicated the presence of mesoporous structures in all synthesized materials. FTIR analysis identified vibrational modes at 1045 and 748 cm-1 (Zr–O stretching), 501 and 450 cm-1 (Zr–O bending), 1023 cm−1 (Zn–O stretching), and 2347 cm−1 (ZnO–ZrO2 interaction). The crystalline nature was confirmed by the XRD spectra, which showed average crystallite sizes of 21.26 nm for ZnO, 22.06 nm for ZrO2 NPs, 23.02 nm for ZrO2–ZnO (1:1), and 25.84 nm for ZrO2–ZnO (1:2). EDX analysis confirmed the presence of only Zn, Zr, and O elements. Both SEM and TEM-SAED revealed that the nanostructures are spherical, with an average particle size of approximately 20 nm. The synthesized nanostructures demonstrated strong antimicrobial activity, as tested by the well-diffusion method against pathogenic bacteria and fungal strains. They also showed photocatalytic degradation of methylene blue (MB) dye under UV–vis light irradiation. ZrO2, ZnO, ZrO2–ZnO (1:1), and ZrO2–ZnO (1:2) exhibited significant photocatalytic performance, with degradation rates of 99.68 %, 97.94 %, 92.98 %, and 97.75 %, respectively, within 60 min.