Composite formation of Thiol-capped Au nanoparticles and mesoporous silica prepared by a sol-gel method

We have previously reported the fabrication of a nanocomposite from dodecanethiol-capped Au nanoparticles (average diameter 2.6 nm) and a silica aerogel. It was found that the Au particles were efficiently adsorbed on a silica wet-gel in organic solvents. In this paper, surface analysis of the silica surface and evaluation of adsorption rates for various solvents, performed to elucidate the nature of the interaction between the capped nanoparticles and the silica gel, are described. These observations indicate that dipole-induced dipole interaction between OH groups on the silica surface and metal cores of the nanoparticles is probably important for the adsorption. It was demonstrated that, by changing the solvent polarity, spatial distribution of the nanoparticles inside the gel can be controlled.