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Innovative design of nanocatalyst with high activity remains to be great challenge. Platinum (Pt) nanoparticle has already demonstrated to be excellent candidates in the field of catalysis. However, the scarcity and high price significantly hinder its large-scale production. In this work, dumbbell-like alloying nanoparticle of platinum-iron/ferroferric oxide (PtFe Fe3O4) was prepared. On one hand, the design of the alloying nanoparticle can manipulate the d-band center of Pt, in further, the interaction with substrates. In addition, the dumbbell-like structured PtFe Fe3O4 can offer heterogeneous interface, of which the interaction between PtFe and Fe3O4, supported by the X-ray photoelectron spectroscopic (XPS) results, leads to the enhanced catalytic efficiency. On the other hand, the introduction of Fe (iron) composition largely decreases the necessary amount of Pt, leading to efficient cost reduction. Moreover, to avoid the aggregation related activity attenuation problem, PtFe Fe3O4 nanoparticle located in cavity of nitrogen heteroatom-doped carbon shell (PtFe Fe3O4@N C) as yolk@shell nanostructure was constructed and its improved catalytic performance was demonstrated towards the reactions of 4-nitrophenol (4-NP) reduction, β-ionone and benzhydrol oxidation.

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.

Hybrid shells of Carbon/TiO2/Fe2O3 (C/TiO2/Fe2O3) were synthesized by sequentially coating TiO2 and Fe2O3 on polystyrene (PS) nanospheres through hydrolysis and hydrothermal procedures, followed by calcination in a N2 atmosphere to crystallize TiO2/Fe2O3 and carbonize PS. In comparison with TiO2/Fe2O3 hollow spheres, C/TiO2/Fe2O3 hybrid shells exhibited remarkably enhanced photocatalytic activity, which was attributed to the effective light absorption and charge separation associated with the introduction of carbon.

Dumbbell-like Au-Fe3O4 nanoparticles are emerging as attractive nanocatalysts in recent years. However, they still suffer from the instability related activity attenuation. Herein, dumbbell-like Au-Fe3O4 nanoparticles encapsulated in N-doped carbon shell (Au-Fe3O4@Carbon) as novel yolk@shell nanocatalysts were synthesized via template assisted method, with which the yolk@shell scaffolds and even the diameter of the hollow space is totally designable. The yolk@shell structured Au-Fe3O4@Carbon was demonstrated to exhibit high stability and enhanced activity towards the reduction of 4-nitrophenol. Moreover, 100% yield was determined for the benzhydrol oxidation reaction taking advantage of the as prepared Au-Fe3O4@Carbon yolk@shell nanocatalysts. Furthermore, the Au-Fe3O4@Carbon nanocatalysts presented herein exhibit superior recyclability, which laid the foundation for its practical application. The mechanism for the enhanced catalytic behavior were clearly addressed. It is anticipated that the elaborate design of this work can lead to the exploration of novel nanocatalysts with superior catalytic performance.

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.

Noble metal-Fe

Multifunctional nanocatalysts of Au@Fe