Abstract
The photocatalyic property of nanosized titania powders has been investigated. The photocatalytic reaction is based on the semiconductor characteristics of TiO2 to reduce the silver ion onto the surface of titania, forming the Ag－TiO2 nanoparticles with core－shell structure.The procedures were divided into three parts. Initially we compared the photocatalytic activity of the commercial TiO2 powders, Hombikat UV－100 and Degussa P－25, with that synthesized by ourselves using sol－gel method. The major phase of titania is anatase and the average size is 10?20 nm. The influences of the pH value, reaction time, UV wavelength, catalyst amount and temperature on the coating were also explored afterward. The surface structure and composition were characterized by TEM and XPS（ESCA）.Under optimum conditions, the thickness of shell obtained is 7.89 nm and the ratio of diameters is 3.2：1. The maximum weight ratio of Ag to Ti is 14﹪.