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.