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°C in air is revealed to show catalytic H₂ evolution from an EDTA aqueous solution with light of λ ≤ 450 nm, in contrast to bare CdS which is stoichiometrically photocorroded. A significant improvement in the activity even with considerable loses 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.