Au@TiO 2 Core-Shell Composites for the Photocatalytic Reduction of CO 2

Au/TiO catalysts in different geometrical arrangements were designed to explore the role of morphology and structural properties for the photocatalytic reduction of CO with H O in the gas-phase. The most active sample was a Au@TiO core-shell catalyst with additional Au nanoparticles (NPs) deposited on the outer surface of the TiO shell. CH and CO are the primary carbon-containing products. Large amounts of H are additionally formed by photocatalytic H O splitting. Shell thickness plays a critical role. The highest yields were observed with the thickest layer of TiO , stressing the importance of the semiconductor for the reaction. Commercial TiO with and without Au NPs was less active in the production of CH and CO. The enhanced activation of CO on the core-shell system is concluded to result from electronic interaction between the gold core, the titania shell, and the Au NPs on the outer surface. The improved exposure of Au-TiO interface contributes to the beneficial effect.