الفهرس 
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Abstract
The TiO2 powders are used extensively in the industry and are investigated as a material presenting very attractive features in a variety of applications. The most promising of these applications include photovoltaic devices, photocatalytic applications (water splitting, waste‐water treatment and antimicrobial agents), electrochromic devices and energy storage. However, titania has some disadvantages such as large band gap energy (3.2 eV for anatase TiO2) (wavelength for excitation < 387.5 nm) which limits its practical use under normal solar light conditions because sunlight is consists of less than 5% of ultraviolet radiation, the fastest electron–hole (e-/h+) recombination on the surface , nanoparticles can lumped or assembled very easily to form larger particles, leading to an adverse effect on catalyst efficiency, separation of catalyst after the reaction and poor adsorption properties.
In the present work we tried to improve the photocatalytic efficiency of TiO2 via two methods: the first one was morphological modifications for increasing surface area and porosity and the second one was chemical modifications via incorporation of additional components (Bi2O3) in the TiO2 structure to extend limit of absorption of wave length range of titania toward visible region.
The composites of titania - MCM-41 were synthesized by two simple and successful techniques namely one-pot synthesis and post-impregnation methods to produce Ti-MCM-41 and TiO2/MCM-41 with various titania contents, respectively. The effect of preparation method and titania contents on the structural, surface, texture and light absorbance properties of the prepared samples were studied.