Preparation of egg-shell type Al2O3-supported US photocatalysts for reduction of H2O to H-2

Alumina-supported cadmium sulfide photocatalysts were prepared for the phot ocatalytic reduction of water to hydrogen using visible light. The activity depends on the nature of interaction between alumina and cadmium and also on the distribution of US on the support. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen desorption and temperature-programmed oxidation. The impregnation of alumina hydrogel with an ammoniacal solution results into a chemical interaction between ca dmium sulfide and alumina and also yields a preferential distribution of ca dmium sulfide on the surface which give a better activity to the photocatal yst. The possible role of ammonia in causing the solute segregation to the surface during the drying stage of the catalyst preparation has been explai ned. (C) 2001 Elsevier Science BN. All rights reserved.