الفهرس 
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Abstract
The research study within this investigation deals with the development of doped semiconductor photocatalysts with high photocatalytic activity, which is stable and capable of degrading and mineralizing a wide class of organic compounds using the UV-Visible light. Different types of TiO2 based photocatalysts have been prepared. Nanocrystalline N-TiO2 and N, F-TiO2,N,F-TiO2 / Carbon nanotube (CNT) nanocomposites and sonicated Ag, Ni, W /TiO2weresynthesized as photocatalysts with more sensitivity in the visible region. Those prepared photocatalysts were characterized using different techniques (e.g. X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Brunauer–Emmett–Teller (BET) surface area, UV-Vis diffused reflectance spectra (DRS) and Raman spectroscopy). The characterization results show that the doping of nitrogen and fluorine enhance the absorption of under-test photocatalysts in the visible region. The sonication of TiO2 also improves the visible light absorption. The photocatalytic activity of the under-test photocatalysts has been determined by oxidative degradation of some organics (e.g.phthalocyanine star polymer, 4-nitrophenol and crystal violet dye). The undertest doped, TiO2/ CNT’s nanocomposites,and sonicated photocatalysts show higher photocatalytic activity than bare and commercial TiO2prepared by the same procedures. The doping of sonicated photocatalysts with (Ag, Ni, W) metals show obvious increment in the photocatalytic activity due to the enhancement of the electron transfer rate.The excellent photocatalytic activity of N, F−TiO2,TiO2 /DWCNT’s, and ultra-sonicated doped-TiO2in the visible region recommend them as potential photocatalysts for many photocatalytic purposes.
Key words: Titanium dioxide, carbon nanotube, doping, sonication, photocatalytic nanocomposites, degradation.