Preparation of highly photocatalytic active CdS/TiO2 nanocomposites by combining chemical bath deposition and microwave-assisted hydrothermal synthesis.

CdS/TiO2 nanocomposites were prepared from Cd and Ti (1:1M ratio) using cetyltrimethylammonium bromide by a two-step chemical bath deposition (CBD) and microwave-assisted hydrothermal synthesis (MAHS) method. A series of nanocomposites with different morphologies and activities were prepared by varying the reaction time in the MAHS (2, 4, and 6h). The crystal structure, morphology, and surface physicochemical properties of the nanocomposites were characterized by X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and N2 adsorption-desorption measurements. The results show that the CdS/TiO2 nanocomposites were composed of anatase TiO2 and hexagonal CdS phases with strong absorption in the visible region. The surface morphologies changed slightly with increasing microwave irradiation time, while the Brunauer-Emmett-Teller surface area increased remarkably. The photocatalytic degradation of methyl orange (MO) was investigated under UV light and simulated sunlight irradiation. The photocatalytic activity of the CdS/TiO2 (6h) composites prepared by the MAHS method was higher than those of CdS, P25, and other CdS/TiO2 nanocomposites. The CdS/TiO2 (6h) nanocomposites significantly affected the UV and microwave-assisted photocatalytic degradation of different dyes. To elucidate the photocatalytic reaction mechanism for the CdS/TiO2 nanocomposites, controlled experiments were performed by adding different radical scavengers. [ABSTRACT FROM AUTHOR]