Defect engineered Li₂O-ZrO₂-NiO multi-metal oxide nanocomposite exhibiting enhanced structural properties optical behavior and cytotoxic activity

Multi-metal oxide nanocomposites have attracted considerable attention due to their tunable physicochemical properties and multifunctional applications. In the present study, a Li2O–ZrO2–NiO multi-metal oxide nanocomposite was successfully synthesized via a facile co-precipitation route followed by controlled thermal treatment. The structural and compositional features of the material were systematically characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT–IR), energy-dispersive X-ray analysis (EDAX), UV–Visible spectroscopy, and thermal analysis (TGA-DTG-DSC). XRD results confirmed the formation of crystalline ZrO2 and NiO phases with nanoscale dimensions, while FT–IR spectra evidenced the formation of characteristic metal–oxygen bonds. The nanocomposite exhibited broad optical absorption spanning the ultraviolet to visible regions (250–950 nm), attributed to defect states and oxygen vacancies induced by lithium incorporation. The thermal stability of the composite was established, and the choice of 900 °C as the calcination temperature for phase-pure oxides was justified by thermal analysis (TGA-DTG-DSC), which exhibited that precursor decomposition and carbonate-to-oxide phase transformation were nearly complete above 680 °C. Elemental analysis confirmed the presence of constituent metals with high purity. The biological activity of the synthesized nanocomposite was evaluated against HepG2 cells using the MTT assay, demonstrating a pronounced concentration-dependent cytotoxicity with an IC50 value of approximately 10 µg/mL. Morphological observations further revealed significant cellular damage, including shrinkage and loss of adhesion, suggesting apoptosis-mediated cell death. The enhanced performance of the nanocomposite can be attributed to synergistic interactions among Li, Zr, and Ni oxides, as well as defect-mediated electronic modifications that promote the generation of reactive oxygen species. Overall, the results highlighted the potential of the Li2O–ZrO2–NiO multi-metal oxide nanocomposite as a promising candidate for advanced catalytic and anticancer applications, offering a simple synthesis strategy and improved functional properties.