Abstract
In this thesis, we have tried to narrow the band gap of anatase TiO2 for enhancing the visible-light absorption and therefore improving the photocatalytic activity of these photocatalysts. Recently, n-type and p-type co-doping has been reported to achieve larger band-gap reduction in anatseTiO2 compared to monodoping of the same elements. In contrast to the above cases, we have co-doped Zr and Ce, which have the same oxidation state as Ti, with the Co dopant to form Co-Zr and Co-Ce co-doped anataseTiO2, respectively. A variety of experimental methods such as x-ray diffraction, Raman spectroscopy, EXAFS, ICP-MS and UV-Vis spectroscopy have been employed in our work. Except for some minor rutile or brookite phase formation, most of the samples were shown to be in the form of doped anatase TiO2. The concentration of dopant atoms successfully incorporated into the sample has also been measured. Our experimental data show that the band gap narrowing effect is substantially enhanced in co-doped samples compared to that in the monodoped samples. Quantitatively, we have found the band gap to reduce from 3.12eV for the Co-doped sample to 2.13eV for Co-Zr codoped sample and from 2.36eV for the Ce-doped sample to 1.90eV for the Co-Ce co-doped sample of TiO2. Our results demonstrate that Co -Zr and Co-Ce co-doping are very effective for narrowing the band gap of anatase TiO2.