Surface-plasmon-induced visible light photocatalytic activity of TiO ₂ nanospheres decorated by au nanoparticles with controlled configuration

This work is focused on the development of a surface plasmon-induced visible light active photocatalyst system composed of silica-titania core-shell (SiO ₂@TiO ₂) nanostructures decorated with Au nanoparticles (Au NPs). The influence of size and distribution of Au NPs on photocatalysis, its fabrication methods, and exploration of the mechanism of visible light activity were investigated. A favorable architecture of SiO ₂ beads with a thin layer of TiO ₂ was decorated with Au NP arrays having different size and areal density. Surface modification of SiO ₂@TiO ₂ leads to a viable and homogeneous loading of Au NPs on the surface of TiO ₂, which renders visible light-induced photocatalytic activity on the whole TiO ₂ surface. An optimized system employing Au NP arrays with 15 nm size and 700/μm ² density showed best catalytic efficiency due to a synergistic effect of the firm contact between Au NPs and TiO ₂ and efficiently coupled SPR excitation. A brief mechanism relating the electron transfer from surface-plasmon-stimulated Au NPs to the conduction band of TiO ₂ is proposed.