CdS quantum dot (QDs)-sensitized Zn1−xCdxS solid solutions were successfully prepared by a simple cation exchange using hydrothermally synthesized ZnS nanoparticles (NPs) and Cd(NO3)2 as precursors. The prepared samples show especially high visible-light photocatalytic H2-production activity from aqueous solutions containing Na2SO3 and Na2S as sacrificial reagents even without a Pt co-catalyst. It was found that this high visible-light photocatalytic H2-production activity is attributed to the quantum size effect of CdS; the presence of CdS QDs alters the energy levels of the conduction and valence bands in the coupled semiconductor system, which favors the electron transfer and enhances photoactivity.
