Pure Rutile TiO2 Research Articles

Improved optical response and photocatalysis for N-doped titanium oxide (TiO2) films prepared by oxidation of TiN

In order to improve the photocatalytic activity, N-doped titanium oxide (TiO2) films were obtained by thermal oxidation of TiN films, which were prepared on Ti substrates by ion beam assisted deposition (IBAD). The dominating rutile TiO2 phase was found in films after thermal oxidation. According to the results of X-ray photoelectron spectroscopy (XPS), the residual N atoms occupied O-atom sites in TiO2 lattice to form TiON bonds. UV–vis spectra revealed the N-doped TiO2 film had a red shift of absorption edge. The maximum red shift was assigned to the sample annealed at 750°C, with an onset wavelength at 600nm. The onset wavelength corresponded to the photon energy of 2.05eV, which was nearly 1.0eV below the band gap of pure rutile TiO2. The effect of nitrogen was responsible for the enhancement of photoactivity of N-doped TiO2 films in the range of visible light.

Selective hydrogenation of acetylene in excess ethylene on micron-sized and nanocrystalline TiO2 supported Pd catalysts

Abstract Physicochemical properties and catalytic performances of Pd catalysts supported on commercial micron-sized and nanocrystalline TiO2 synthesized by sol–gel and solvothermal method were studied for the selective hydrogenation of acetylene in the presence of excess ethylene. While acetylene conversions were found to be merely dependent on Pd dispersion, ethylene selectivity appeared to be strongly affected by the presence of Ti3+ in the TiO2 samples. The use of pure anatase TiO2 (either micron- or nano-sized) that contained significant amount of Ti3+ as supports for Pd catalysts gave high ethylene selectivities, while the use of pure rutile TiO2 (without Ti3+ present) resulted in ethylene loss. The results suggest that the effect of Ti3+ on the TiO2 supports was more important for high ethylene selectivity than the effect of TiO2 crystallite size for selective acetylene hydrogenation over Pd/TiO2 catalysts.

In situ epitaxial growth of TiO2 on RuO2 nanorods with reactive sputtering

In this work, TiO2 deposition on RuO2 nanorods with reactive sputtering was studied. The TiO2 deposition was performed in situ after the RuO2 nanorod deposition at the same substrate temperature of 450 °C. The morphology examination and structure analysis have indicated a uniform and pure rutile TiO2 deposition on RuO2 nanorods. High-resolution transmission electron microscopy images also revealed an epitaxial growth of TiO2 on RuO2 nanorods. Such a low-temperature fabrication technique for one-dimensional (1D) heteronanostructure may apply to other functional materials. Since RuO2 is a good electric conductor, 1D heteronanostructures made from RuO2 nanorods are expected to exhibit enhanced functionality particularly in electrical and electrochemical applications.

Preparation and photoactivity of nanostructured anatase, rutile and brookite TiO2 thin films

Photoactive films consisting of pure anatase, brookite or rutile TiO2 were prepared by dip coating from water dispersions obtained by using TiCl4 as the precursor under similar mild experimental conditions.

Hydrothermal synthesis of rutile TiO 2 nanoparticles using hydroxyl and carboxyl group-containing organics as modifiers

Phase pure rutile TiO 2 nanoparticles were hydrothermally synthesized using amorphous TiO 2 as a starting material and hydroxyl and carboxyl group-containing organics as modifiers at low temperature and low pH. The prepared rutile TiO 2 nanoparticles were of narrow size distribution and small average particle size. The acidity and nonpolarity of the organic modifiers both significantly affected the average particle sizes and particle size distributions of the resulting rutile TiO 2 nanoparticles.

Visible Light Cr(VI) Reduction and Organic Chemical Oxidation by TiO2 Photocatalysis

Here we report the simultaneous Cr(VI) reduction and 4-chlorophenol (4-CP) oxidation in water under visible light (wavelength > 400 nm) using commercial Degussa P25 TiO2. This remarkable observation was attributed to a synergistic effect among TiO2, Cr(VI), and 4-CP. It is well known that TiO2 alone cannot remove either 4-CP or Cr(VI) efficiently under visible light. Moreover, the interaction between Cr(VI) and 4-CP is minimal if not negligible. However, we found that the combination of TiO2, Cr(VI), and 4-CP together can enable efficient Cr(VI) reduction and 4-CP oxidation under visible light. The specific roles of the three ingredients in the synergistic system were studied parametrically. It was found that optimal concentrations of Cr(VI) and TiO2 exist for the Cr(VI) reduction and 4-CP oxidation. Cr(VI) was compared experimentally with other metals such as Cu(ll), Fe(lll), Mn(IV), Ce(IV), and V(V). Among all these metal ions, only Cr(VI) promotes the photocatalytic oxidation of 4-CP. The amount of 4-CP removed was directly related to the initial concentration of Cr(VI). The system was also tested with four other chemicals (aniline, salicylic acid, formic acid, and diethyl phosphoramidate). We found that the same phenomenon occurred for organics containing acid and/or phenolic groups. Cr(VI) was reduced at the same time as the organic chemicals being oxidized during photoreaction under visible light. The synergistic effect was also found with pure anatase TiO2 and rutile TiO2. This study demonstrates a possible economical way for environmental cleanup under visible light.

Co distribution in ferromagnetic rutile Co-doped TiO2 thin films grown by laser ablation on silicon substrates

Pure rutile Co-doped TiO2 films were fabricated by the pulsed-laser-deposition technique on silicon substrates from a ceramic target. Under the right fabrication conditions, Co concentration in the films could be almost the same as in the target, and films under various conditions all are ferromagnetic well above room temperature. Even though Rutherford backscattering spectroscopy measurements show that Co atoms mostly localize near the surface of the films and exist less in deeper levels, other experimental evidence shows that the ferromagnetism does not come from Co segregations, but from the Co-doped TiO2 matrix. Rutile Ti1−xCoxO2 thin films grown by a very simple technique on low-cost silicon substrates showing a Curie temperature (TC) above 400 K appear to be very attractive to applications.

Monophasic TiO2 films deposited on SrTiO3(100) by pulsed laser ablation

Single phase TiO2 thin films, of either rutile or anatase structure, have been prepared on SrTiO3(STO)(100) substrates by in situ pulsed laser deposition (PLD). Thermodynamically unfavorable, for films deposited on STO(100) substrate directly, pure anatase TiO2(00l) films were formed even when a rutile TiO2(110) substrate was used as a target. On the other hand, pure rutile TiO2(110) films were obtained by oxidizing PLD TiN films in-situ at temperatures higher than 700 °C. The optimized deposition conditions for preparing TiN and TiO2 films were reported. The crystalline structure, surface morphology, and electronic structure of these films were examined. A mechanism of the process of film formation is also proposed.