Mesoporous, nanocrystalline, Zinc-doped TiO 2 nanoparticles were synthesized by surfactant-assisted solgel method. The X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and UV-VIS spectrometer techniques were used to characterize the synthesized products. XRD results confirm the formation of the anatase phase for the TiO 2 nanoparticles, with crystallite sizes in the range of 12.6-18.1 nm. The small crystallite size and doping with Zinc ion inhibit phase transformation and promote the growth of the TiO 2 anatase phase. The SEM and TEM micrographs revealed the spherical-like morphology with average diameter of about 12-18 nm which is in agreement with XRD results. The optical study shows that doping ions lead to an increase in the absorption edge wavelength and a decrease in the band gap energy of titania. Photocatalytic activity of the synthesized nanomaterials was successfully tested for photodegradation of methyl red as model pollutant under UV light. The photocatalytic activity results confirm that the doped nanoparticles show higher activity than undoped titania. The small grain size, high crystallinity, high specific surface area and decrease in the band gap energy of doped titania may be responsible for the high photocatalytic activity.

Carbon-doped MoO 3 samples were prepared by impregnation method. The effect of addition of polyethylene glycol-400 (PEG-400) and carbon (0, 1, 2 and 3 wt. %) as substrates, were investigated systematically to get the desired phase of carbon-doped MoO 3 material. The carbon used was prepared from the natural sources such as Acacia arabika plant wood. The resulting samples were calcined at 500 • C. The effect of PEG-400 and carbon composite on the structure, particle size and morphology of MoO 3 was investigated. The samples thus prepared gave better control of particle size and porosity. The prepared samples were characterized using XRD, SEM-EDS and FT-IR techniques. Photocatalytic activities of the samples were studied with degradation of methylene blue. The 3 wt.% carbon-doped MoO 3 modified by PEG-400 (CMP3) sample showed enhanced photocatalytic activity in comparison with the undoped samples.

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