Preparation and photocatalytic activities of a semiconductor composite of CdS embedded in a TiO2 gel as a stable oxide semiconducting matrix

A semiconductor composite of CdS particles embedded in a TiO2 gel after heat treatment at 250 degrees C in air is revealed to show catalytic H-2 evolution from an EDTA aqueous solution with light of lambda greater than or equal to 450 nm, in contrast to ban CdS which is stoichiometrically photocorroded. A significant improvement in the activity even with considerable losses of CdS in the gel during the heat treatment suggests that the TiO2 gel crystallized into anatase can prevent photocorrosion of CdS embedded therein, and serve as a semiconducting matrix to facilitate charge transfer from the embedded CdS to Pt at the surfaces of the gel. (C) 1998 Elsevier Science B.V.