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Catalysts play a critical role in producing most industrial chemicals and are essential to environmental remediation. Under the demands of sustainable development, environment protection, and cost-related factors, it has been suggested that catalysts are sufficiently separable and conveniently recyclable in the catalysis process. Magnetite (Fe₃O₄) nanomaterials provide a possible way to achieve this goal, due to their magnetism, chemical stability, low toxicity, economic viability, etc. Therefore, Fe₃O₄-based materials are emerging as an important solid support to load heterogeneous catalysts and immobilize homogeneous catalysts. Moreover, the addition of magnetic character to catalysts will not only make their recovery much easier but also possibly endow catalysts with desirable properties, such as magnetothermal conversion, Lewis acid, mimetic enzyme activity, and Fenton activity. The following review comprises a short survey of the most recent reports in the catalytic applications of Fe₃O₄-based magnetic materials. It contains seven sections, an introduction into the theme, applications of Fe₃O₄-based magnetic materials in environmental remediation, electrocatalysis, organic synthesis, catalytic synthesis of biodiesel, and cancer treatment, and conclusions about the reported research with perspectives for future developments. Elucidation of the functions and mechanisms of Fe₃O₄ nanoparticles (NPs) in these applications may benefit the acquisition of robust and affordable protocols, leading to catalysts with good catalytic activity and enhanced recoverability. Full article

Three novel magnetically-recoverable solid acid catalysts (hydrophobic catalysts Fe₃O₄@SiO₂-Me&PrSO₃H, Fe₃O₄@SiO₂-Oc&PrSO₃H and hydrophilic catalyst Fe₃O₄@SiO₂-PrSO₃H) were synthesized by introducing organic propylsulfonic acid and alkyl groups to Fe₃O₄@SiO₂ nanocomposites. We characterized these catalysts by FT-IR, EDS, XRD, VSM and SEM, and found that they had excellent core-shell structure and magnetic responsiveness. We also explored the impact of surface hydrophobicity on activity and stability of catalysts in ethyl acetate (EAC) synthesis reaction. The results indicated that: for reactivity and reusability, Fe₃O₄@SiO₂-Oc&PrSO₃H > Fe₃O₄@SiO₂-Me&PrSO₃H > Fe₃O₄@SiO₂-PrSO₃H. This was because octyl and methyl groups could build a hydrophobic layer on the surfaces of Fe₃O₄@SiO₂-Oc&PrSO₃H and Fe₃O₄@SiO₂-Me&PrSO₃H, and this could effectively prevent water molecules from poisoning active sites; the hydrophobicity of octyl was stronger than methyl. Fe₃O₄@SiO₂-Oc&PrSO₃H also showed higher catalytic activity in the external aqueous reaction system, which indicated that it had good water toleration. Moreover, we could easily separate Fe₃O₄@SiO₂-Oc&PrSO₃H from the reaction mixture with an external magnetic field, in the meanwhile, its reactivity could still remain above 80% after reusing 6 times. Full article