Doped TiO₂ and TiO₂ Nanotubes: Synthesis and Applications

Abstract

TiO(2) is one of the most investigated compounds in contemporary materials science. Due to a set of virtually unique electronic properties, it finds intense use in photoelectrochemical applications such as photocatalysis or solar cells. The main drawback in view of direct exploitation of solar-light-based effects is its large band gap of >3 eV. Visible-light-activated TiO(2) can be prepared by doping (band-gap engineering) through incorporation or decoration with other metal ions, nonmetal ions, and semiconductors. Most recently, efforts in TiO(2) research have been even more intensified by the finding of self-organized nanotubular oxide architectures that can be prepared by a simple but optimized anodization of Ti metal surfaces. These nanotubular geometries provide large potential for enhanced and novel functional features. This Review examines doped TiO(2) and in particular TiO(2) nanotubes. Various types of dopants, doping methods, and applications of modified TiO(2) nanotubes are discussed.

Toward tailored functionality of titania nanotube arrays: Interpretation of the magnetic-structural correlations

“…Both of these effects can contribute to the observed unit cell volume expansion. [37][38][39] Such an expansion in the crystal unit cell upon introducing oxygen vacancies is also reported for other nanostructured transition-metal oxides such as cerium oxide nanoparticles. 38,40 Meanwhile, the larger crystallite size attained during annealing in a reducing environment is consistent with enhanced growth conditions that are facilitated in such an environment, with larger, more defective unit cells donating higher atomic mobility pathways for crystallite growth.…”

Carbon-Doped TiO2 and Carbon, Tungsten-Codoped TiO2 through Sol–Gel Processes in the Presence of Melamine Borate: Reflections through Photocatalysis

“…Our results with C-doped catalysts also indicate that the doped sites, despite improving the visible light absorption characteristics, are not directly involved in the phocatalytic decomposition of surface adsorbed organics, and most of the resulting photocatalysis occurs through O 2 -related solution reactions. [64][65][66][67][68][69] Another critical point is that typically C doping leads to extremely low concentrations of C in the structure. We cannot assume that this concentration is sufficient to raise the bulk valence-band level by >0.5 eV and it is more likely that we are simply adding discrete energy levels at energies somewhat above the upper edge of the valance band.…”

The contribution of vanadium and titanium on improving methylene blue decolorization through heterogeneous UV-Fenton reaction catalyzed by their co-doped magnetite

“…For Ti foil, its absorption edge which is defined as the maximum of derivative at the absorption edge locates at 4965.0 eV. For rutile (␣-TiO 2 ), its absorption edge locates at 4981.4 eV with a pre-edge peak at 4971.7 eV [32], while the XANES spectrum of anatase (␥-TiO 2 ) shows an absorption edge at 4978.9 eV with a more obvious pre-edge peak at 4970.5 eV and a shoulder peak at 4979.5 eV [33]. For ilmenite (FeTiO 3 ), the XANES spectrum shows an absorption edge at 4980.4 eV with a strong pre-edge peak at 4970.4 eV and two shoulder peaks at 4979.4 and 4984.8 eV.…”