Papers by Author: Lilian Tichagwa

Abstract: The sol gel synthesis method was used to prepare carbon and nitrogen doped titanium dioxide (TiO₂) photo-catalyst using titanium tetrachloride (TiCl₄) as the precursor. Doping was carried out to modify the absorption band edge of titanium dioxide. To avert the problem associated with use of powder TiO₂, the photo-catalyst was immobilized on glass support using tetraethyl orthosilicate (TEOS), which served as a binder and precursor for silicon dioxide (SiO₂). The prepared photo-catalytic materials were characterized by FT-IR, XRD, TEM, BET and DRS. The photo-catalytic efficiency of titanium dioxide immobilized on glass support was evaluated using the degradation of methyl orange (MeO) and phenol red (PRed) under ultraviolet and visible light irradiation. Doping with carbon and nitrogen, and incorporation of silicon dioxide into the titanium dioxide matrix allowed utilization of visible light by the prepared TiO₂-SiO₂ nanocomposites. Photo-degradation tests were carried out for doped and undoped photo-catalyst. An increased rate of photo-oxidation of methyl orange and phenol red was observed under visible light irradiation as compared to UV light irradiation.

Abstract: Visible light-sensitive carbon doped titanium dioxide nanoparticles (C-TiO₂) were prepared by a sol-gel method. The carbon dopant was obtained from glucose. The dopant level incorporated into the TiO₂ lattice structure was varied by using different concentrations of the carbon source solution. The nanoparticles were characterized by X-ray diffraction (XRD), BET Surface area, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Scanning X-ray photoelectron spectroscopy (SXPS) and Diffuse reflectance spectroscopy (DRS). The presence of carbon in the TiO₂ lattice was determined by SXPS. The DRS results revealed that carbon doping reduced the band gap of TiO₂. Doping was also found to cause a reduction in the particle size of the TiO₂ nanoparticles and enhance anatase to rutile phase transformation. The photocatalytic activities of the prepared samples were evaluated by the photocatalytic degradation of methyl orange. The carbon doped TiO₂ showed a higher photocatalytic activity than degussa P25 and undoped TiO₂.