Facile Synthesis of Magnetic Hierarchical Core-Shell Structured Fe3O4@PDA-Pd@MOF Nanocomposites: Highly Integrated Multifunctional Catalysts

A magnetic hierarchical core-shell structured Fe3O4@PDA-Pd@[Cu-3(btc)(2)] nanocomposite has been fabricated via a facile layer-by-layer assembly method. It contains a core of polydopamine (PDA)-modified magnetic Fe3O4 nanoparticles (NPs), a transition layer of Pd NPs, and a porous outer shell of copper-based metal-organic framework (MOF) with controllable thickness. This novel nanocomposite was characterized by TEM, FTIR, XRD, XPS, N-2 adsorption-desorption isotherms, and VSM. The prepared Fe3O4@PDA-Pd@[Cu-3(btc)(2)] (n=5) nanocomposite shows ultrahigh catalytic activity for the 4-nitrophenol reduction and Suzuki-Miyaura coupling reactions of aryl halides (Br, Cl) with arylboronic acids. Moreover, the nanocomposite also can be easily separated by an external magnet and reused at least 8runs with excellent yields for both the reactions. The catalyst has outstanding catalytic performance, mainly because the integration of [Cu-3(btc)(2)] with Fe3O4@PDA-Pd that combines the advantages of each component could exhibit a synergistic effect in the catalytic system.