EFFECTS ON CO OXIDATION ACTIVITY OF NANO-SCALE AU ISLANDS AND TIO2 SUPPORT PREPARED BY THE IONIZED CLUSTER BEAM METHOD

Catalytic activity in titania-supported gold (Au/TiO2) is associated w ith nano-scale Au islands on a substrate coated with TiO2. The Au isla nds were prepared by the ionized-cluster-beam (ICB) method. Both rutil e and anatase types of TiO2 films were obtained by adjusting the depos ition conditions of the reactive ICB method. The average diameter of g old islands was kept constant at about a few nm, and their density inc reased by ionizing and accelerating the Au beams. The measurements of the temperature dependence of CO oxidation indicated that the catalyti c activity was enhanced by using an anatase type of support and by usi ng Au islands deposited at an acceleration voltage of 3 kV. The high c atalytic activity was obtained at a temperature of 100-150 degrees C. The diameter and density of Au islands and the surface state of TiO2 s upport play an important role in catalytic activity.