Multifunctional nanocomposites constructed from Fe3O4–Aunanoparticle cores and a porous silica shell in the solution phase

Abstract

This work is directed towards the synthesis of multifunctional nanoparticles composed of Fe₃O₄–Au nanocomposite cores and a porous silica shell (Fe₃O₄–Au/pSiO₂), aimed at ensuring the stability, magnetic, and optical properties of magnetic-gold nanocomposite simultaneously. The prepared Fe₃O₄–Au/pSiO₂ core/shell nanoparticles are characterized by means of TEM, N₂ adsorption-desorption isotherms, FTIR, XRD, UV-vis, and VSM. Meanwhile, as an example of the applications, catalytic activity of the porous silica shell-encapsulated Fe₃O₄–Au nanoparticles is investigated by choosing a model reaction, reduction of o-nitroaniline to benzenediamine by NaBH₄. Due to the existence of porous silica shells, the reaction with Fe₃O₄–Au/pSiO₂ core/shell nanoparticles as a catalyst follows second-order kinetics with the rate constant (k) of about 0.0165 l mol⁻¹ s⁻¹, remarkably different from the first-order kinetics with the k of about 0.002 s⁻¹ for the reduction reaction with the core Fe₃O₄–Au nanoparticles as a catalyst.