Synthesis and Characterization of Au-Loaded Core/Shell Mesoporous Silica Spheres Containing Propyl Group in the Shell

A series of organically functionalized core/shell monodispersed mesoporous silica spheres (MMSSs) containing bulky propyl group in the shell and thiol group as coordination sites of Au ions in the core were prepared. The thickness and molar ratio of propyl group in the shell are systematically controlled by changing the amount and composition of additional silica precursor. The core/shell MMSSs were converted to monodispersed gold-nanoparticle-embedded nanoporous spheres. It is found that the propyl group in the shell acts as a barrier to prevent the migration of gold nanoparticles. Gold nanoparticles are retained within the core after heat treatment, because of the steric hindrance and hydrophobic character of the propyl group. The absorption band of the gold nanoparticles showed blue-shift not only with decreasing thickness of the shell but also with increasing reduction temperature.