Growth of quantum-confined CdS nanoparticles inside Ti-MCM-41 as a visible light photocatalyst

CdS nanocrystallites have been successfully incorporated into the mesopores of Ti-MCM-41 by a two-step method involving ion-exchange and sulfidation. The X-ray diffraction patterns (XRD), UV-vis absorption spectra (UV-vis), photoluminescence spectra (PL), Raman spectra and N-2 adsorption-desorption isotherms were used to characterize the structure of the composite materials. It is found that most of the CdS nanocrystallites are about 2.6 nm, less than the pore diameter of Ti-MCM-41. The CdS nanocrystallites inside the mesopores of Ti-MCM-41 host show a significant blue shift in the UV-vis absorption spectrum. Under irradiation of visible light (lambda > 430 nm), the composite material has greater and more stable photocatalytic activity for hydrogen evolution than bulk CdS, which can be explained by the effective charge separation between the CdS nanocrystallites and mesoporous Ti-MCM-41. (C) 2007 Elsevier Ltd. All rights reserved.