Nanocrystalline anatase TiO(2) materials with different specific surface areas and pore size distributions are prepared via sol-gel and miniemulsion routes in the presence of surfactants. The samples are characterized by X-ray diffraction, nitrogen sorption, transmission electron microscopy, and electrochemical measurements. The materials show a pure anatase phase with average crystallite size of about 10 nm. The nitrogen sorption analysis reveals specific surface areas ranging from 25 to 150 m(2) g(-1) . It is demonstrated that the electrochemical performance of this material strongly depends on morphology. The mesoporous TiO(2) samples exhibit excellent high rate capabilities and good cycling stability.

Mesoporous silica particulate structures of different morphologies from particles to capsules have been prepared by combining the sol-gel process with the cooperative self-assembly in inverse miniemulsion. We report a novel synthetic approach at room temperature, with low surfactant concentrations (5 and 10 mol %, relative to the precursor), and a short synthesis time of only a few hours. As a precursor, glycol-modified silane (tetrakis(2-hydroxyethyl)orthosilicate, EGMS) is used, which shows the advantage of being highly water-soluble. The precursor (EGMS) and the structuring surfactant (cetyltrimethylammonium bromide, CTAB) were dissolved in hydrochloric acid and dispersed in a mixture of hydrocarbons (Isopar M) by ultrasonication. In this synthesis, two different surfactants were used simultaneously. One surfactant (CTAB) acts as a lyotropic template, whereas the second surfactant is an amphiphilic block copolymer (PE/B-b-PEO) that stabilizes the droplets. For template removal, the final material was calcined. The obtained materials were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and nitrogen sorption (Brunauer-Emmett-Teller (BET) methodology). The effect of synthesis conditions such as the amount of templating surfactant (CTAB), the temperature during ultrasonication, the reaction time, the pH value, and the amount of stabilizing surfactant (PE/B-b-PEO) on cooperative self-assembly, morphology, and specific surface area were investigated. Shortly after ultrasonication, porous particles a few hundreds of nanometers in size are formed, which are transformed to capsules and finally to porous flakes with increasing reaction time. This transformation is strongly influenced by the amount of stabilizing surfactant (PE/B-b-PEO). By simply varying the amount of PE/B-b-PEO, the morphology and mesostructural ordering, as well as the porosity, can be tuned over a wide range.

A series of mesoporous anatase-type TiO(2) doped with zirconium (0-50 mol% Zr) was synthesized by combining the sol-gel process with the inverse miniemulsion technique. Nanoparticles between 100 and 300 nm were directly prepared from acidic precursor solutions of titanium glycolate (EGMT) and zirconium isopropoxide. The miniemulsion technique is a simple and convenient method to synthesize nanoparticles of homogeneous size because the reactions (here hydrolysis and condensation) take place in the confined space of nanodroplets (several hundreds of nanometres) and therefore in a highly controlled manner. For low doping levels (0-7.1 mol% Zr), Zr(x)Ti(1 - x)O(2) solid solutions were formed where Zr was uniformly dispersed into the anatase framework. For higher amounts of zirconium (Zr >or= 7.1 mol%), the crystallization of zirconium titanate (ZrTiO(4)) occurred at a low temperature of 650 degrees C and it was obtained as a pure material for 47.4 mol%

Cerium(IV) oxide nanoparticles were synthesized using an inverse miniemulsion technique with cerium nitrate hexahydrate as precursor. The resulting nanocrystallites are as small as 5 nm with a specific surface area of 158 m² g⁻¹ after calcination at 400 °C. With the addition of cetyltrimethylammonium bromide (CTAB) or (poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)) triblock copolymers (PEO-PPO-PEO) as template in the miniemulsion droplets, the specific surface area can be increased up to 255 m² g⁻¹. The miniemulsions were characterized by dynamic light scattering (DLS) and the obtained oxides were examined by x-ray diffraction (XRD), nitrogen sorption (BET and BJH), and transmission electron microscopy (TEM). The catalytic activity of the resulting ceria was investigated for the temperature-programmed oxidation (TPO) of methane.

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