Photoreduction of Silver Ion in a Titanium Dioxide Suspension

Quantum yields ranging from 0.084 to 0.191 were obtained for the reduction of Ag+ by irradiation of light at 365 nm on a TiO2 surface in aqueous solutions containing 1×10−4 to 1×10−2 mol dm−3 AgClO4. Some features of the reduction were preliminarily examined with the aid of an electrochemical measurement of TiO2 sinter. It is proposed that some conduction-band electrons, produced in the TiO2 by irradiation, transfer to Ag+ adsorbed on the TiO2 surface and that positive holes react with water molecules. The photoreduction of Ag+ is optically sensitized by addition of Uranine. The apparent quantum yield (the number of reacted ions/the number of photons incident to the suspension) of the dye-sensitized photoreduction of Ag+ is 0.01.