Role In Red Shift Research Articles

Preparation and Characterization of MWCNTs-TiO<sub>2</sub>: Ce/Fe Photocatalyst

Titanium dioxide (TiO2), which was doped by Ce and Fe, was coated on multi-walled carbon nanotubes (MWCNTs) through a conventional sol-gel method. We use IR to evaluate the possible functional groups and XRD, UV and SEM to characterize the structure and surface morphology of MWCNTs. The results suggest that the TiO2, which composed of nano-scale particles, was well coated on MWCNTs via chemistry bond. The visible light photo catalytic was mentioned of its red shift in UV spectrum. And we suggest that there may be a certain mechanism between TiO2and MWCNTs during visible light processing that MWCNTs has play an important role in red shift and visible light absorption.

First-principles calculations on implanted TiO2 by 3d transition metal ions

3d transition metal (V, Cr and Fe) ions are implanted into TiO2 by the method of metal ion implantation. The electronic band structures of TiO2 films doped 3d transition metal ions have been analyzed by ab initio band calculations based on a self-consistent full-potential linearized augmented plane-wave method within the first-principle formalism. Influence of implantation on TiO2 films is examined by the method of UV-visible spectrometry. The results of experiment and calculation show that the optical band gap of TiO2 films is narrowed by ion implantation. The calculation shows that the 3d state of V, Cr and Fe ions plays a significant role in red shift of UV-Vis absorbance spectrum.

First principles calculations on anatase implanted by V+

V+ were implanted into anantase films by metal ion implantation. The electronic band structures of TiO2 films doped with V+ were calculated using a self-consistent full-potential linearized augmented plane-wave method within the first principles formalism. Influence of implantation on TiO2 films were examined by ultraviolet-visible spectrometry. The results of experiment and calculation show that the optical band gap of TiO2 films is narrowed by ion implantation. The calculation shows that the 3d state of V+ plays a significant role in red shift of ultraviolet-visible absorbance spectrum. It was also found that the optical band gap of TiO2 films decreases, with increasing amount of V+.

Anatase TiO2 and red-shift introduced by doping with Fe:pseudopotential calculations and ultraviolet spectroscropy

The crystal structure and electronic band structure of undoped and Fe-doped anatase TiO2 have been investigated by using the plane-wave ultrasoft pseudopotential method in the generalized gradient approximation (GGA). The calculation shows that Fe-doping introduces a localized level and narrowing of band gap in TiO2. The t2g state of the dopant plays a significant role in red-shift of spectrum. The previous prediction is confirmed by our experiment.