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 (Fe 3 O 4 ) and Fe 3 O 4 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. • The synthesis methods of Fe 3 O 4 and Fe 3 O 4 -based nanocomposites (NCs) have been reviewed. • The properties of Fe 3 O 4 have been discussed. • Degradation mechanism of organic pollutants by Fe 3 O 4 and Fe 3 O 4 -based NCs was explained. • Mechanism of hydrogen production by Fe 3 O 4 and Fe 3 O 4 -based NCs was discussed. • The applications of Fe 3 O 4 -based NCs for environmental sustainability and biomedicines have been discussed.