Multifunctional nanocomposites constructed from Fe3O4-Au nanoparticle cores and a porous silica shell in the solution phase

This work is directed towards the synthesis of multifunctional nanoparticles composed of Fe3O4-Au nanocomposite cores and a porous silica shell (Fe3O4-Au/pSiO(2)), aimed at ensuring the stability, magnetic, and optical properties of magnetic-gold nanocomposite simultaneously. The prepared Fe3O4-Au/pSiO(2) core/shell nanoparticles are characterized by means of TEM, N-2 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/pSiO(2) 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