Applications of Magnetic Nanomaterials in Heterogeneous Catalysis

Magnetic nanomaterials show promising applications in heterogeneous catalysis because of their ease of separation and good reusability. The magnetization saturation values of magnetic nanoparticles mainly depend on finite-size and surface effects. For small magnetic nanoparticles, the formation of domain walls provides a high energy state and the particles aggregate easily in clusters or clumps. To avoid agglomeration, magnetic nanoparticles can be coated with different shells (e.g., silica, carbon, metal, metal oxide, and polymer) to isolate them from external environments. Because of high surface area of magnetic nanoparticles, many active species can be supported on the surface to enhance the catalytic activity. This review focuses on recent developments of various magnetic nanomaterials in heterogeneous catalysis, including hydrogenation reaction, Suzuki–Miyaura reaction, oxidation reaction, chiral catalysis, enzyme catalysis, photocatalysis, electrocatalysis, and photoelectrochemical catalysis. Different synthesis strategies for magnetic nanomaterials are summarized. The active sites, stability, and catalytic mechanisms are discussed. Challenges and perspectives for magnetic nanomaterials in commercial applications are documented.