Ultra-fast microwave-assisted reverse microemulsion synthesis of Fe3O4@SiO2 core–shell nanoparticles as a highly recyclable silver nanoparticle catalytic platform in the reduction of 4-nitroaniline

Abstract

A novel microwave-assissted reverse microemulsion method was applied to prepare Fe₃O₄@SiO₂ core–shell nanoparticles rapidly for the first time. The morphology of the core–shell structure is controlled by tunning the reaction parameters. Nanoparticles with a very thin SiO₂ coating layer (2.5 nm) containing a single Fe₃O₄ nanoparticle (8–9 nm) are produced. These core–shell nanoparticles can be used as solid catalytic supports for Ag nanoparticles and applied in 4-nitroaniline reduction. Transmission electron microscopy showed that the core–shell nanoparticles were decoracted with Ag nanoparticles of 7 nm in diameter. The crystal structures of the Fe₃O₄ and Ag nanoparticles were confirmed by X-ray diffraction. These Ag/Fe₃O₄@SiO₂ nanocomposites showed high catalytic efficiency and recycling properties even after 20 times of repetation.