Precise adjustment of structural anisotropy and crystallinity on metal-Fe3O4 hybrid nanoparticles and its influence on magnetic and catalytic properties

In the present study, we demonstrate the precise adjustment of the morphology and crystallinity of metal (Pd or Au)-Fe3O4 hybrid nanoparticles by reaction kinetics control. The nucleation and growth of the Fe component on the Pd surface are precisely controlled by using a mixture of capping agents, oleylamine and oleic acid. After the oxidation, the resulting Pd-Fe3O4 structures are produced as yolk-shell, irregular core-shell, and dumbbell-like NPs. Along with the morphology change, the average crystal domain size of Fe3O4 and the void gap between the metal cores and the shells are simultaneously adjusted. The crystal domain sizes of Fe3O4 directly influence the magnetic properties, and the structural arrangement of the Pd cores and the Fe3O4 shells leads to a large difference of conversion yields in the Suzuki coupling reactions. Our approach is successfully extended to other metal- Fe3O4 hybrid systems, such as those of Au and Fe3O4.