PHOTOCATALYTIC PROPERTIES OF CDS AND CDS-ZNS MIXTURES INCORPORATED INTO THE INTERLAYER OF LAYERED COMPOUNDS

Semiconductor particles composed of CdS and mixed CdS-ZnS were incorporated into the interlayers of layered compounds such as H4Nb6O17, H2Ti4O9, montmorillonite and layered double hydroxides, [M(II)1-xM(III)x(OH)2](CO3)x/2.nH2O (M(II) = Mg2+, Zn2+, M(III) = Al3+, x = 0.33), by the chemical reactions between S2- and Cd2+-Zn2+ and/or Cd(edta)2--Zn(edta)2- in the interlayers. The incorporated particles seemed to be very small, less than 1 nm thick. The band gap energies of CdS and CdS-ZnS mixtures in the interlayer were significantly larger than those of normal-crystalline ones. The CdS-ZnS mixtures incorporated into the interlayers were capable of efficient hydrogen evolution following irradiation with visible light in the presence of Na2S, Na2SO3 and/or 2-aminoethanol as a sacrificial donor. The hydrogen production activities of the CdS-ZnS mixtures incorporated into the interlayers were superior to those of unsupported CdS-ZnS. The incorporation of the CdS-ZnS mixtures in the interlayer of a semiconductor such as H2Ti4O9 and H4Nb6O17 was much more efficient in enhancing the hydrogen production activity than when an insulator such as montmorillonite and layered double hydroxide was used.