Synthesis and characterization of a microfibrous TiO2-CdS/palygorskite nanostructured material with enhanced visible-light photocatalytic activity

A microfibrous TiO2-CdS/palygorskite (TiO2-CdS/Pal) nanostructured material was prepared following a colloidal route based on the controlled hydrolysis of alkoxides in the presence of cetyltrimethylammonium-palygorskite gel. The cationic surfactant coating on the surface of Pal as a template assured organophilic environment for the formation of TiO2 nanoparticles. The presence of CdS on the surface of TiO2/Pal not only extended its photoresponse to the visible-light region, but also accelerated the photogenerated electron transfer from the inorganic sensitizer (CdS) to TiO2. The new photocatalysts were characterized by XRD, N-2 adsorption-desorption, SEM, TEM, XPS, FTIR and UV-vis spectroscopy and their photocatalytic activities were evaluated by the degradation of methylene blue (MB) under visible light irradiation. This TiO2-CdS/Pal nanocomposite exhibited much higher visible light photocatalytic activity than TiO2/Pal and CdS/Pal. The apparent rate constant (k(app)) for TiO2-CdS/Pal nanocomposites, TiO2/Pal and CdS/Pal were calculated and TiO2-CdS/Pal-0.4 showed the highest rate constant (3.00 x 10(-3) min(-1)) among all the prepared samples. (C) 2013 Elsevier B.V. All rights reserved.