Photoreduction of silver ion on the surface of titanium dioxide single crystals

Abstract

Mean quantum yields ranging from 0.0053 to 0.16 have been determined for the reduction of Ag⁺ by irradiation with 365 nm light on a TiO₂ single-crystal surface in aqueous solutions containing 1 × 10^–5 to 1 × 10^–2 mol dm^–3 AgNO₃. The electrochemical behaviour of the same crystal electrode has been investigated in order to clarify the mechanism of silver reduction. It is proposed that some conduction-band electrons, produced in the TiO₂ by irradiation, transfer to the Ag⁺ adsorbed on the TiO₂ surface. A convenient expression for the dependence of the mean quantum yield on the Ag⁺ concentration is derived from the viewpoint of semiconductor electrochemistry.