Synthesis and Photochemical Properties of Semiconductor/Layered Compound Nanocomposites

CdS and Cd_0.8Zn_0.2S pillars were constructed in the interlayer of hectorite, HNbWO₆, H₄Nb₆O₁₇ and H₂Ti₄ O₉ by the intercalation reactions. The thicknesses of the semiconductors incorporated were less than 1 nm and the band gap energies of them were slightly larger than those of normal crystalline ones. CdS and Cd_0.8Zn_0.2S pillared compounds showed photocatalytic activity for hydrogen evolution and nitrate reduction under visible light irradiation in the presence of sacrificial hole acceptor such as Na₂S and methanol. The photocatalytic activities of the semiconductors incorporated were superior to those of unsupported ones. The incorporation of semiconductors in the interlayers of semiconductor layered compounds such as HNbWO₆, H₂Ti₄O₉ and H₄Nb₆O₁₇ was much more efficient in enhancing the hydrogen production activity than when an insulator such as hectorite was used. The heterogeneous electron transfer from guest CdS to host semiconductor seemed to play an important role to enhance the photocatalytic activity.