Synthesize of Tri-Metal Oxide MnO2-ZnO-CeO2 Nanocomposites via Co-Precipitation Technique for Biomedical and Environmental Applications.

Tri-metallic MnO₂-ZnO-CeO₂ nanocomposites were successfully synthesized via a co-precipitation method. Structural characterization confirmed the formation of orthorhombic MnO₂, hexagonal ZnO, and cubic CeO₂ phases, with an average crystallite size of approximately 18 nm. The nanocomposites exhibited a narrow band gap of 2.36 eV, enabling efficient visible-light absorption and enhanced photocatalytic activity. FTIR analysis confirmed M-O stretching vibrations, while photoluminescence spectra revealed defect-related emission bands attributed to newly formed energy levels. Nitrogen adsorption-desorption isotherms indicated a high surface area with a uniform mesoporous structure, featuring a pore diameter centered at 2.450 nm. HR-TEM analysis showed spherical particles with a coarse, granular nanostructure and an average particle size of ~ 37 nm. Elemental mapping and XPS confirmed the presence and oxidation states of Mn, Zn, Ce, and O. Electrochemical studies revealed significant pseudocapacitive behavior, with a maximum areal capacitance of 111.26 mF/cm² at 5 mV/s and minimal charge transfer resistance. Antibacterial assays demonstrated strong activity against Staphylococcus aureus, with a maximum inhibition zone of 14 mm. Cytotoxicity evaluation showed a concentrate dependent response, reducing MCF-7 cell viability to 12% at 1000 µg/mL. Photocatalytic degradation of methylene blue reached 89.8% within 40 min, following pseudo-first-order kinetics. The effects of pH, catalyst dosage, and dye concentration were systematically examined, and reusability tests confirmed the catalyst stability. These results underscore the potential of MnO₂-ZnO-CeO₂ nanocomposites for effective wastewater treatment applications.