Photocatalytic Hydrogen Evolution from Water on Nanocomposites Incorporating Cadmium Sulfide into the Interlayer

An efficient hydrogen evolution was achieved on layered metal oxides incorporating CdS in the interlayer, which were prepared by direct cation exchange reaction and a sulfurization process. The photocatalytic activity of the composites intercalating CdS was superior to those of neat CdS and the physical mixture of CdS and metal oxides. The photocatalytic activities strongly depend on the structure of the layered metal oxides and the solutions containing S2- ions as hole scavengers. The substitution of Nb for partial Ti in the layered composite of K2Ti4O9 gave rise to the increase in the content of CdS incorporated in the interlayer, and the quick transference of the electrons in a CdS nano-pillar through the layer into the surface of photocatalysts. Thus the photocatalytic activity was enhanced. Addition of sulfite ions, which efficiently suppress the disulfide formation, allowed hydrogen to evolve at a higher rate. As a hole scavenger, Na2S was superior to Na2SO3 with respect to increasing the hydrogen evolution. Further improvement of the hydrogen evolution could be achieved by loading the Pt on the CdS-incorporated layered compounds. The photocatalytic hydrogen production under visible light was confirmed by the fact that H2 was detected when UV light was removed.