Sono- and photochemical routes for the formation of highly dispersed gold nanoclusters in mesoporous titania films

A sono- and photochemical approach has been developed to incorporate highly dispersed gold nanoclusters into mesoporous TiO2 films. The first step involves the sonication of a TiO2 film immersed in a gold chloride solution. This effectively removes the air trapped in the porous film matrix and drives the gold chloride into the pore channels, leading to a homogeneous adsorption of ionic Au in the TiO2 mesoporous matrix. The second step takes advantage of the photocatalytic property of TiO2 to reduce the adsorbed Au ions to Au-0. As the gold nanoclusters thus produced are stabilized by the TiO2 mesonetwork, no organic capping molecules are required. Highly dispersed Au/TiO2 nanoheterojunction arrays can be obtained using this interesting approach.