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Journal of Nanomaterials
Volume 2016, Article ID 6581691, 11 pages
http://dx.doi.org/10.1155/2016/6581691
Research Article

TiO2-CdS Nanocomposites: Effect of CdS Oxidation on the Photocatalytic Activity

1Laboratoire de Chimie Inorganique, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax, Tunisia
2Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal
3LSME, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3018 Sfax, Tunisia

Received 20 July 2016; Accepted 28 September 2016

Academic Editor: Domenico Acierno

Copyright © 2016 A. Hamdi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Nanocomposites TiO2-CdS with different relative contents of CdS (molar ratios Cd/Ti = 0.02, 0.03, 0.05, 0.1, 0.2, and 0.5) were studied. The structural, photophysical, and chemical properties were investigated using XRD, Raman spectroscopy, XPS, GSDR, and LIL. XRD and Raman results confirmed the presence of TiO2 and CdS with intensities dependent on the ratio Cd/Ti. The presence of CdSO4 was detected by XPS at the surface of all TiO2-CdS composites. The relative amount of sulphate was dependent on the CdS loading. Luminescence time-resolved spectra clearly proved the existence of an excitation transfer process from CdS to TiO2 through the luminescence emission from TiO2 after excitation of CdS at nm, where no direct excitation of TiO2 occurs. Photodegradation of a series of aromatic carboxylic acids—benzoic, salicylic, 4-bromobenzoic, 3-phenylpropionic, and veratric acids—showed a great enhancement in the photocatalytic efficiency of the TiO2-CdS composites, which is due, mainly, to the effect of the charge carriers’ increased lifetime. In addition, it was shown that the oxidation of CdS to CdSO4 did not result in the deactivation of the photocatalytic properties and even contributed to enhance the degradation efficiency.