Synthesis, properties, and applications of Fe₃O₄ and Fe₃O₄-based nanocomposites: A review

Iron oxide nanoparticles and their nanocomposites have been widely studied for diverse applications ranging from water treatments to energy production, diagnostics and therapeutics. The remarkable physicochemical characteristics of iron-based nanomaterials (Fe-NMs) such as superparamagnetic behavior, higher saturation magnetization values, biocompatibility, chemical stability, structural diversity, high abundance, and tunable surface chemistry amplify their potential applications in various fields. Due to these desirable properties, Fe-NMs have demonstrated remarkable efficacy in water purification, facilitating the removal of diverse range of contaminants through magnetic separation, adsorption, and catalysis. These Fe-NMs also serve as high-performance catalysts for hydrogen evolution reaction. In addition, their biocompatibility and magnetic targeting capabilities render them suitable for anticancer drug delivery, improving therapeutic outcomes. Keeping the importance of Fe-NMs in various fields, the most promising synthesis methods of magnetite (Fe₃O₄) and Fe₃O₄ based nanoparticles and nanocomposites including co-precipitation, green synthesis, hydrothermal, sol-gel, and electrochemical methods have been summarized in this review. Additionally, the application of magnetite and magnetite-based nanocomposites in the fields of wastewater treatment and green energy production have been comprehensively discussed. This review also highlights the biomedical applications of Fe-NMs such as drug delivery. Finally, the major challenges and hurdles in practical applications of Fe-NMs for green energy production and environmental sustainability have been addressed.