Shape-Controlled Synthesis of Magnetic Iron Oxide@SiO<sub>2</sub>–Au@C Particles with Core–Shell Nanostructures
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Abstract
The
preparation of nonspherical magnetic core–shell nanostructures
with uniform sizes still remains a challenge. In this study, magnetic
iron oxide@SiO<sub>2</sub>–Au@C particles with different shapes,
such as pseduocube, ellipsoid, and peanut, were synthesized using
hematite as templates and precursors of magnetic iron oxide. The as-obtained
magnetic particles demonstrated uniform sizes, shapes, and well-designed
core–shell nanostructures. Transmission electron microscopy
(TEM) and energy dispersive X-ray spectroscopy (EDX) analysis showed
that the Au nanoparticles (AuNPs) of ∼6 nm were uniformly distributed
between the silica and carbon layers. The embedding of the metal nanocrystals
into the two different layers prevented the aggregation and reduced
the loss of the metal nanocrystals during recycling. Catalytic performance
of the peanut-like particles kept almost unchanged without a noticeable
decrease in the reduction of 4-nitrophenol (4-NP) in 8 min even after
7 cycles, indicating excellent reusability of the particles. Moreover,
the catalyst could be readily recycled magnetically after each reduction
by an external magnetic field