Encapsulating Pt Nanoparticles through Transforming Fe3O4 into MIL-100(Fe) for Well-Defined Fe3O4@Pt@MIL-100(Fe) Core-Shell Heterostructures with Promoting Catalytic Activity.

Metal-organic framework (MOF)-based magnetic Pt catalyst Fe3O4@Pt@MIL-100(Fe) core-shell heterostructures were prepared through transforming Fe3O4 into MIL-100(Fe) in benzene-1,3,5-tricarboxylic acid solution along with encapsulating the Pt nanoparticles successively adsorbed onto the surface of the Fe3O4 nanosphere and the continuously forming surfaces of the growing MIL-100(Fe) crystals. This method circumvented the obstacles, controlling the formation of metal nanoparticles (MNPs) inside MOFs or regulating growth of MOFs around the MNPs, for preparing an MNP-MOF composite catalyst. The obtained well-defined Fe3O4@Pt@MIL-100(Fe) core-shell heterostructure was shown promoting catalytic activity on the reduction of 4-nitrophenol due to the synergistic effect between the Pt nanoparticles and the MIL-100(Fe) shell and recycling convenience due to the rapid separation of the Fe3O4 core under an external magnetic field.