Alumina-supported cadmium sulfide photocatalysts for hydrogen production from water: Role of dissolved ammonia in the impregnating solution

Alumina-supported cadmium sulfide photocatalysts were prepared for the phot ocatalytic reduction of water to hydrogen using visible Light. The activity depends on the loading of CdS in catalysts and on the solution used for th e impregnation of alumina for catalyst preparation. The catalysts were char acterized by X-ray diffraction and X-ray photoelectron spectroscopy. Those catalysts, which had CdS in crystalline form and preferentially distributed on the surface, showed better activity. The crystallinity of CdS was relat ed to the loading of CdS in the catalyst. The use of an ammoniacal impregna ting solution resulted in a preferential distribution of CdS on the surface of alumina. The possible role of ammonia in causing the solute segregation to the surface during the drying stage of the catalyst preparation has bee n explained.