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

Abstract

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.