Au@TiO2 core-shell nanostructures with high thermal stability

A catalyst system consisting of core–shell nanostructures with Au core and porous TiO2 shell was synthesized and characterized for room temperature CO oxidation. The core–shell structures were prepared by colloidal methods starting from pre-formed 3 nm Au particles in solution and then adsorbed on to high-surface area, functionalized hydrophobic Al2O3 support. The obtained Au@TiO2/Si–Al2O3 catalyst showed higher activity and thermal stability when compared to a conventional Au/TiO2 sample prepared by impregnation of the same Au particles on to commercial titania P25. The core–shell catalyst was able to maintain its activity and 3 nm Au particles size upon calcination up to 600 °C, whereas the Au/TiO2 sample was found to sinter. Furthermore, it was found that the crystallization of TiO2 was suppressed in the core–shell structure, resulting in a thin layer of small TiO2 particles, which is favorable for the dispersion and thermal stability of Au nanoparticles.