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 with nano-scale Au islands on a substrate coated with TiO2. The Au islands were prepared by the ionized-cluster-beam (ICB) method. Both rutile and anatase types of TiO2 films were obtained by adjusting the deposition conditions of the reactive ICB method. The average diameter of gold islands was kept constant at about a few nm, and their density increased by ionizing and accelerating the Au beams. The measurements of the temperature dependence of CO oxidation indicated that the catalytic activity was enhanced by using an anatase type of support and by using Au islands deposited at an acceleration voltage of 3 kV. The high catalytic activity was obtained at a temperature of 100–150°C. The diameter and density of Au islands and the surface state of TiO2 support play an important role in catalytic activity.