Visible‐light response photocatalytic water splitting over CdS/TiO2 and CdS–TiO2/metalosilicate composites

SUMMARY In this work, we have synthesized two different phases of CdS nanoparticles, CdS/TiO2 composites and their supported form on ZSM-5 type metalosilicates (ferrisilicate and aluminosilicate) as CdS–TiO2/metalosilicate composites. The photocatalytic performance of these samples was evaluated by monitoring the amount of hydrogen evolved from water under visible-light irradiation. The supported composites of TiO2–CdS/metalosilicate exhibited a higher photocatalytic activity in the photocatalytic water splitting than that of CdS/TiO2 composites under visible-light irradiation, suggesting an important role of support. Metalosilicate as a support, which can offer a very high surface area, provides effective and homogenous dispersion of the CdS/TiO2 composite on the external surface or within the pores of metalosilicate and inhibits agglomeration of the formed composite. We observed that using the solvothermal method for the synthesis of CdS and the hydrothermal method for the synthesis of CdS/TiO2 or CdS–TiO2/metalosilicate results in the enhancement of the photocatalytic activity of these composite compared with other procedures, which has been reported previously. We have realized that the support of the CdS/TiO2 composite on ferrisilicate enhances the photocatalytic activity; however, using aluminosilicate as a support results in the abatement of the photocatalytic activity in comparison with the unsupported composite. This can be attributed to the presence of partially occupied ‘d’ orbitals in the electronic configuration of Fe3+ in the structure of ferrisilicate which can interact with TiO2 molecular orbitals. This interaction leads to the effective distribution of the composite on the support and the decreasing crystallite size of the composite and then enhancement of the photocatalytic activity. Copyright © 2014 John Wiley & Sons, Ltd.