Tailoring Mesoporous Titania Features by Ultrasound-Assisted Sol-Gel Technique: Effect of Surfactant/Titania Precursor Weight Ratio

A mesoporous titania structure has been prepared using the ultrasound-assisted sol-gel technique in order to find out a way to tailor its structure. The TiO2 obtained was compared to the same version of titania but synthesized by a conventional sol-gel method with the objective of understanding the effect of ultrasound in the synthesis process. All synthesis experiments were focused on the preparation of a titania photocatalyst. Thus, the anatase photocatalytic active phase of titania was proven by X-ray diffraction. Additionally, the ultrasonation treatment proved to increase the crystallinity of titania samples, being one of the requirements to having good photocatalytic activity for titania. The influence of surfactant/titania precursor weight ratio on the structural (XRD), textural (N2-sorption measurements), morphological (TEM), surface chemistry (FTIR) and optical properties (UVDR) was investigated. It was observed that the crystallite size, specific surface area, band gap energy and even photocatalytic activity was affected by the synergism occurring between cavitation effect and the surfactant/titania precursor weight ratio. The study yielded interesting great results that could be considered for further application of ultrasound to tailor mesoporous titania features via sol-gel soft template synthesis, against conventional sol-gel process.

Structure of the amorphous titania precursor phase of N-doped photocatalysts

Amorphous titania samples prepared by ammonia solution neutralization of titanyl sulphate have been characterized by chemical and thermal analyses, and with reciprocal-space and real-space fitting of wide-angle synchrotron X-ray scattering data.

Titania/mesoporous silica nanotubes with efficient photocatalytic properties

Ordered nanocrystalline titania-mesoporous silica nanotube structures are synthesized by hydrolysis of the titania precursor inside pours silica shell. Silica coating surrounding carbon nanotubes was further removed by thermal reduction. The proposed method of functionalization silica channels with the titania nanoparticles preclude aggregation of TiO2nanoparticles. The nanocrystalline silica/titania (mt-SiO2/TiO2) nanotubes were prepared according to the describe method has high specific surface area and possesses excellent photocatalytic properties capable of decomposing phenol and methylene blue in a short time. Since the nanocrystalline TiO2is produced in the wall of the mesoporous silica tube, phenol or dye molecules can react with TiO2nanoparticles from both the inside and outside.

Synthesis of Hollow Titania Photocatalytic Particles Using Yeast as Templates

Hollow inorganic particles have attracted considerable interest for a variety of applications. In this work, yeast powder was used as a bio-template to fabricate yeast/titania core-shell spheres. A titania precursor was deposited via the hydrolysis of tetraisopropyl titanate. Triethanolamine was employed to control the reaction rate of the sol-gel process. The hollow titania particles with a diameter of approximately 4 m and a thickness of approximately 54 nm were successfully obtained after calcination of the core-shell spheres at 700 °C. The crystal structure of the particles was anatase. The specific surface area and the average pore diameter were 21.4 m2/g and 1.6 nm, respectively. The photocatalytic activity of the hollow particles was higher compared with that of solid particles.

A New Route to Synthesis of Titanium Silicalite-1 by Ball-Milling

Titanium Silicalite-1 (TS-1) was successfully synthesized from amorphous silica and titania powders by using a ball-milling method. In this method, amorphous fumed silica and anatase titania powders were ground in a planetary ball mill to produce a silica-titania precursor. The obtained precursor was then hydrothermally treated where TPABr was used as a template to obtain titanium silicalite-1 (TS-1). The XRD and UV-vis spectra indicate that the titanium in anatase with octahedral coordination is incorporated into the silica-titania precursor and the final TS-1 framework with a tetrahedral coordination. SEM image shows that TS-1 synthesized in this work appears in a shape of elongated prism with a dimension of about 3μm×1μm×0.2μm. This method gives a simple new approach to the synthesis of TS-1 using inexpensive silicon source, titanium source and template.