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 d 0 -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 TiO 2 polymorphs as well as complex oxide materials with the help of the novel water-soluble titanium complexes is provided.

Brookite, the Least Known TiO2 Photocatalyst

“…Pure brookite was also obtained by Štengl and Králová [16] by hydrothermal treatment of a solution of titanium peroxo-glycolate complex at pH 9.5 and 220 °C for 24 h. The formation of brookite was attributed to the structure of the complex anion that contains four titanium atoms coordinated by glycolic acid and peroxo groups in a dimer-like structure that is connected to another dimer through bridging oxo groups. As shown in Figure 8, this structure closely resembles the architecture of brookite [84].…”

“…Recently, pure brookite has been successfully synthesized by hydrothermal treatment of water-soluble titanium complexes [84] such as titanium-peroxo-glycolate [16,[85][86][87][88] and titanium bis(ammonium lactate) dihydroxide [23,89].…”

A new peroxo-route for the synthesis of Mg–Zr mixed oxides catalysts: Application in the gas phase acetone self-condensation

“…The peroxocomplexes of some transition metals could be considered as a "green" alternative to metal alkoxide precursors [21]. Although, different studies on the synthesis of peroxocomplexes [21,22] have been reported, studies on zirconium peroxocomplexes as the precursors for ZrO 2 or zirconium-based complex oxides are scarce.…”

“…Although, different studies on the synthesis of peroxocomplexes [21,22] have been reported, studies on zirconium peroxocomplexes as the precursors for ZrO 2 or zirconium-based complex oxides are scarce. Gao et al [23] thin-film preparation, whereas Park et al [24] found some advantages of peroxo-mediated procedure for ZrO 2 films synthesis, as such as the homogeneous distribution on the substrate and high density of the film.…”

Synthesis of spindle and square bipyramid-shaped anatase-type titanium dioxide crystals by a solvothermal method using ethylenediamine

“…7)9) However, as to anatase, only nanosized particles could be obtained as long as hydrothermal treatment of the watersoluble titanium complexes is relied on. 10), 11) That's why a study directed to versatile morphological control of anatase using watersoluble titanium complexes is curious.…”