Influence of the metal work function on the photocatalytic properties of TiO2 layers on metals.

The photocatalytic properties of titanium dioxide (TiO2 ) layers on different metal plates are investigated. The metal-semiconductor interface can be described as a Schottky contact, and is part of a depletion layer for the majority carriers in the semiconductor. Many researchers have demonstrated an increase in the photocatalytic activity, due to the formation of a metal-semiconductor contact that are obtained by deposition of small metal islands on the semiconductor. Nevertheless, the influence of a Schottky contact remains uncertain, sparking much interest in this field. The immobilization of nanoparticulate TiO2 layers by dip-coating on different metal substrates results in the formation of a Schottky contact. The recombination rate of photoinduced electron-hole pairs decreases at this interface provided that the thickness of the thin TiO2 layer has a similar magnitude to the depletion layer. The degradation of dichloroacetic acid in aqueous solution and of acetaldehyde in a gas mixture is investigated to obtain information concerning the influence of the metal work function of the back contact on the efficiency of the photocatalytic process.