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Noble metal-Fe3O4 dumbbell-like nanoparticles have aroused considerable attention because of their high potential as heterogeneous nanocatalysts. The designed synthesis of the advanced architecture of noble metal-Fe3O4 dumbbell-like nanoparticles with both improved catalytic activity and stability is still a challenge. Herein, through the combination of yolk@shell and dumbbell-like nanostructures, dumbbell-like Pt-Fe3O4 nanoparticles encapsulated in N-doped carbon hollow nanospheres (Pt-Fe3O4@N-carbon) as a special yolk@shell nanostructure were developed. In comparison with Pt-Fe3O4 dumbbell-like nanoparticles, Pt-Fe3O4@N-carbon yolk@shell nanoparticles showed improved catalytic activity and stability toward the liquid-phase 4-nitrophenol reduction and β-ionone oxidation, making them a promising candidate for catalysis applications.

Multifunctional nanocatalysts of Au@Fe3O4/m-SiO2 yolk@shell hybrids had been developed through a template-assisted synthesis, where Fe3O4 nanoparticles (∼12 nm) and m-SiO2 shells were sequentially assembled on surfaces of Au/SiO2 core/shell templates, followed by selective etching of the inner SiO2 cores, leading to the formation of Au@Fe3O4/m-SiO2 yolk@shell hybrids. The Fe3O4 nanoparticles were implanted in the inner surfaces of m-SiO2 shells with partially exposed surfaces to the inner cavity. The novel design not only ensures a high surface area (540.0 m2/g) and saturation magnetization (48.6 emu/g) of the hybrids but also enables interaction between Au and Fe3O4 nanoparticles. Catalytic tests toward the reduction of 4-nitrophenol in the presence of NaBH4 indicated that Au@Fe3O4/m-SiO2 yolk@shell nanocatalysts not only showed high stability and recyclability but also maintained improved catalytic activity as a result of the synergetic effect resulting from Au and Fe3O4 interactions.