Catalytic properties of SiO2 @ Au core/shell nanostructures.

The catalytic properties of silica nanoparticles capped with gold nanoparticles core/shell nanostructures (SiO2 @ Au) and the relation between catalytic activity of gold particles and the silica size are investigated in this paper. The gold nanoparticles with 3.5 nm diameters were attached to silica spheres with sizes of 78, 105, and 304 nm, respectively. The reduction of potassium hexacyanoferrate (III) by NaBH4 was designed by using the SiO2 @ Au core-shell nanocomposites as catalysts. The experimental results demonstrated that the catalytic activity of SiO2 @ Au nanostructures depends not only on the concentration of gold but also on the silica size. Gold particles supported on larger SiO2 spheres (304 nm) show high catalytic activity. In addition, it was found that the position of surface plasma resonance (SPR) peak of Au nanoparticles changes little. The results suggested that the size and morphology of gold particles were kept unchanged after the reduction of hexacyanoferrate (III), showing that the catalytic activity of gold particles was kept during the catalytic reaction.