Water-soluble Titanium Complex Research Articles

Synthesis of titanium-based ceramics by a new synthetic route of water-soluble titanium complexes

We developed a new synthetic route of water-soluble complexes using TiCl4 and Ti(SO4)2 as starting materials. The yield of Ti and the removal rate of the Cl− ion were over 85 and 98%, respectively. The lactato titanium complex solution obtained by this new synthetic route remained stable for more than 3 months without any precipitation. Single-phase CaTiO3, SrTiO3, and BaTiO3 were synthesized from the lactato titanium complex by heating at 873 K for 5 h. The nano-structured CaTiO3, SrTiO3, and BaTiO3 particle sizes were 50, 30, and 30 nm in diameter, respectively, and smaller than those obtained by the solid-state method. We have succeeded in the synthesis of very fine particles of CaTiO3, SrTiO3, and BaTiO3 at a temperature 400 K lower than that required for the solid-state method.

Aerosol assisted fabrication of two dimensional ZnO island arrays and honeycomb patterns with identical lattice structures

Two dimensional island arrays and honeycomb patterns consisting of ZnO nanocrystal clusters were fabricated on predefined TiO2 seed patterns prepared by vacuum free, aerosol assisted wet-chemical synthesis. The TiO2 seed patterns were prepared by applying an aerosol of a water soluble titanium complex on hexagonally close-packed polystyrene bead arrays for different lengths of time. Scanning electron microscopy revealed that a dot array grows into a honeycomb shape as increasing amounts of the precursor were deposited. ZnO nucleation on substrates with a dot array and honeycomb patterns resulted in the formation of two discrete patterns with contrasting fill fractions of the materials.

Application of Water-Soluble Titanium Complexes as Precursors for Synthesis of Titanium-Containing Oxides via Aqueous Solution Processes

Abstract The growing significance of nanocrystalline inorganic functional materials in the fields of catalysis, electronics, and energy conversion together with the increasing demand of the society for safer, softer, and “greener” technologies has drawn considerable attention of the researchers toward water-based solution processes for synthesis of such materials. In this respect complex oxides, containing d0-transition metals, such as Ti, Nb, Ta, or Si represent an outstanding challenge for materials chemists due to the extremely narrow range or almost complete absence of suitable precursor compounds compatible with aqueous systems. In the recent 10 years, a remarkable progress has been achieved in the development of new water-soluble complexes of titanium and considerable experience was accumulated in the application of these compounds for synthesis of nanocrystalline titanium-containing materials. The essential knowledge of coordination chemistry of such water-soluble titanium complexes is reviewed in this work, which succeeded to identify the key structural features responsible for stability of the compounds against hydrolysis and to provide guidelines for synthesis of these complexes. Finally, an extensive overview of highly selective aqueous solution based synthesis of TiO2 polymorphs as well as complex oxide materials with the help of the novel water-soluble titanium complexes is provided.

Sub-10 nm strontium titanate nanocubes highly dispersed in non-polar organic solvents

Strontium titanate (SrTiO(3)) nanoparticles with well defined cubic shape and sub-10 nm size that are highly dispersible in non-polar organic solvents were successfully synthesized by hydrothermal (HT) processing. Water-soluble titanium complexes and strontium hydroxide were employed as precursors. When the HT process was carried out without oleic acid, the SrTiO(3) particles obtained were relatively large and aggregated. However, SrTiO(3) nanocubes that are highly dispersible in hexane were obtained via the HT process using oleic acid and hydrazine.

水溶性チタン錯体を用いたW/Oエマルション法によるTiO2(B)ナノ粒子の水熱合成

水溶性チタン錯体を用いたW/Oエマルション法によるTiO2(B)ナノ粒子の水熱合成

Hydrothermal synthesis of brookite type TiO2 photocatalysts using a water-soluble Ti-complex coordinated by ethylenediaminetetraacetic acid

Nanocrystalline brookite titanium oxide was prepared by hydrothermal treatment of a water-soluble titanium complex with ethylenediaminetetraacetic acid (EDTA). In this work, we examined the effect of synthesis conditions such as reaction time, titanium concentration and solution pH on the brookite phase formation and its photocatalyitic performance. It was found that hydrothermal treatment of the titanium complex may yield anatase and brookite phases, and their ratio can be varied depending on titanium concentration. Single phase brookite could be prepared when titanium concentration in the starting solution was higher than 0.25 mol/dm3, while lower concentration favors formation of anatase. Remarkably, brookite could be synthesized from the Ti-EDTA complex in the wide range of pH including both acidic and basic media. The samples prepared from Ti-EDTA complex demonstrated higher photocatalytic activity in terms of NO gas decomposition than the brookite powders synthesized from Ti-glycolate complex or commercial TiO2 photocatalyst P25. Higher photocatalytic activity of powders obtained from Ti-EDTA complex aqueous solution is explained by higher surface area of smaller but well-crystallized brookite particles that can be achieved when this new titanium complex is employed.

Selective synthesis of nano-crystalline TiO2polymorphs from new water-soluble titanium complexes

Selective synthesis of nano-crystalline TiO₂polymorphs from new water-soluble titanium complexes

Direct synthesis of brookite-type titanium oxide by hydrothermal method using water-soluble titanium complexes

It was demonstrated that brookite-type titanium oxide can be directly synthesized by the hydrothermal treatment of novel water-soluble titanium complexes under basic conditions in the presence of an additive. In particular, single-phase brookite was synthesized from the titanium–glycolate complex at a pH of about 10 in the presence of excess NH3 aqueous solution or ethylenediamine, and powder thus obtained consisted of rod-like nanosized particles. It was suggested that the structures of titanium complexes are important for the formation of brookite.

Hydrothermal synthesis of TiO2 nano-particles using novel water-soluble titanium complexes

Hydrothermal treatment of a series of water-soluble titanium complexes resulted in the formation of TiO2. Rutile, anatase or a mixture of both can be synthesized by varying the ligands. The titania obtained was composed of nano-sized particles with large specific surface areas. These TiO2 powders exhibited high photocatalytic activity for NOx decomposition. In particular, they demonstrated higher activity than P25 (Degussa) under visible-light irradiation.

水溶性チタン錯体を用いた水熱法によるTiO2(B)の直接合成

水溶性チタン錯体を用いた水熱法によるTiO2(B)の直接合成

Hydrothermal Synthesis of Nanosized Titania Photocatalysts Using Novel Water-Soluble Titanium Complexes

Highly crystalline titania nano-particles were synthesized by hydrothermal method using novel stable water-soluble titanium complexes. It was confirmed that single phase anatase, rutile and brookite, which can be rarely synthesized as a single phase, can be obtained by varying the ligand in the complex and pH of the aqueous solution. TEM observations and BET specific surface area measurements had shown that these samples consisted of nanosized particles of 5~200 nm and had high specific surface areas of 25~150 m2/g. According to UV-visible diffuse reflectance spectra, these titania samples absorbed light in the visible region (λ > 400 nm). Photocatalytic activities in NO oxidation reaction exhibited by synthesized titania powders under the irradiation by UV- visible light were higher than the activity of the commercial TiO2 photocatalyst P25 (Degussa). Especially, under illumination by only visible light of above 510 nm wavelength, photocatalytic activity of the obtained specimens exceeded that of P25 more than four times. We also clearly demonstrated that single phase brookite had high photocatalytic activity for NO oxidation.

Microwave-Assisted Hydrothermal Synthesis of Brookite Nanoparticles from a Water-Soluble Titanium Complex and Their Photocatalytic Activity

Nanoparticles of brookite titanium oxide were prepared by microwave-assisted hydrothermal (MH) method at 200°C (heating time 5 min) for 0-60 minutes starting from the titanium peroxo glycolate complex in basic solution. The effect of microwave heating on the morphology of the brookite particles was examined. The samples were characterized by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). It was found that all powders were composed of single phase brookite and contained two different types of particles. The activity in photodecomposition of oxalic acid by the samples prepared using MH method was higher than activities of brookite nanoparticles synthesized by the conventional hydrothermal method.

A Water‐Soluble Titanium Complex for the Selective Synthesis of Nanocrystalline Brookite, Rutile, and Anatase by a Hydrothermal Method

A complex pattern: Single-phase brookite, rutile, and rutile–anatase nanoparticles can be prepared from the new water-soluble titanium(IV) complex (NH4)6[Ti4(C2H2O3)4(C2H3O3)2(O2)4O2]⋅4 H2O. It appears that the structural similarity of the complex anion to the brookite architecture allows the directional synthesis of brookite nanopowders in a pure form (see scheme).

Urinary and Serum Titanium: Assessment as an Indicator of Exposure to Ammonium Citratoperoxotitanate (IV) and Its Influence on Renal Function

Ammonium citratoperoxotitanate IV (TAS-FINE) is a water-soluble titanium complex used to synthesize a photocatalytic titanium(IV) oxide film. This study was aimed to investigate the LD50, dose-response, time-course response, and renal toxicity of TAS-FINE using an animal model. Serum titanium (S-Ti) and its 24-h urinary excretion (U-Ti) were determined by inductively coupled plasma-argon emission spectrometry (ICPAES) after a single oral TAS-FINE administration to male Wistar rats. The LD50 of TAS-FINE was 7.97 g/kg body weight in 24 h, and its half-life was 3.78+/-1.28 d for S-Ti and 2.19+/-0.09 d for U-Ti. Although TAS-FINE was not easily absorbed in the gastrointestinal tract, it was distributed into the bloodstream in a dose-dependent manner. Within 24 h, 0.189% of administrated Ti was excreted via urine. It was speculated that TAS-FINE formed conjugates with serum constituents that resulted in nephrotoxicity resulting from an allergic reaction. The observed indices in this study were revealed to be good indicators for TAS-FINE exposure. The analytical method and animal model described in this study will help to further elucidate details about human exposure to TAS-FINE, which in recent times has become an occupational and environmental toxicant of concern.

Electrochemically assisted deposition of titanium dioxide on aluminium cathodes

Adherent, uniform, and porous TiO2 films have been obtained at ambient temperature by a novel electrochemical process involving the simultaneous cathodic electrodeposition of a Ti(IV)–peroxo complex and electrophoretic deposition of nanocrystalline TiO2 particles on an Al cathode. Electrodepositions were performed using an electrolytic suspension containing a water-soluble titanium complex stabilized with a peroxo ligand and a commercial nanocrystalline TiO2 powder (Degussa P25), and by applying a constant cell voltage between 2.0 and 4.5 V. The reduction process favours the decomposition of the soluble titanium complex to yield an amorphous TiO2 precipitate on the cathode. This amorphous precipitate also acts as a binder to the nanocrystalline TiO2 particles. The whole assembly shows photocatalytic activity for the degradation of salicylic acid without the need of thermal post-treatment.