Facile Phyto fabrication of Mg interconnected ZrO2 nanocomposites for effective decontamination of infected water bodies

This study uses Eucalyptus leaf extract to present a green synthesis approach for pristine and magnesium-doped
zirconium oxide (Z and ZM) nanocomposites. The synthesis was performed with varying doping concentrations
(1 %, 3 %, and 5 %) and characterized using advanced techniques. The XRD analysis confirmed the crystalline
nature, with peaks corresponding to the monoclinic phase of ZrO2 and the cubic phase of MgO. Notably, Mg
incorporation reduces the crystallite size from 32.27 nm (Z) to 11.8 nm (ZM3). FE-SEM analysis revealed uni�formly distributed quasi-spherical particles with smooth surfaces. At higher doping levels, particles elongated,
indicating significant structural changes and stronger interparticle forces. FT-IR and EDX analysis confirmed the
presence of Zr, Mg, and O elements. The UV–Vis spectra revealed that Mg doping in ZrO2 resulted in redshifts of
the absorbance peaks, accompanied by a decreasing bandgap of 2.8eV for higher concentrations (ZM3). Under
100 min solar irradiation, ZM3 achieves the highest photocatalysis of 95.43 % with k → 0.027 min↑1 for
Rhodamine B (RhB), and 97.08 % with k → 0.03 min↑1 for Brilliant Blue (BB). ZM3 also exhibits superior cycling
stability, retaining 90.3 and 92.1 % efficiency after five consecutive runs. Antibacterial activity demonstrated
that ZM3 exhibited the highest zones of inhibition at 100 μg/mL, measuring 19.2 mm against S. aureus and 18.3
mm against E. coli. The performance gains are attributed to Mg-induced oxygen vacancies and defect states that
enhance charge separation, suppress e↑/h↓ recombination, and increase ROS generation. The study highlights
the potential of phyto-fabricated Mg-doped ZrO2 nanocomposites as a sustainable, reusable photocatalyst for
applications in wastewater treatment and antimicrobial applications.