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Soft – chemistry preparation of porous globules of nanocrystalline TiO2 with improved photocatalytic properties

Alexey Tarasov 1Ksenia L. Dubova Eugene A. Goodilin Yuri D. Tretyakov 

1. M.V. Lomonosov Moscow State University, Vorobyevy gory, Moscow 119992, Russian Federation

Abstract

Nanomaterials based on TiO2 promise a wide range of unique properties and highly attractive applications. They are of great interest in photocatalysis, as electrode materials, oxidation catalysts, sensors, self-cleaning surface components.

Most of TiO2 preparation methods such as sol-gel, hydrothermal, aerosol pyrolysis, are usually not enough flexible and do not allow to control key functional properties of produced materials. In particular, various works focused on ultrasonic spray pyrolysis apply the only method of thermal decomposition of aerosols of titanium alkoxides precursors. In the present work we developed a novel flexible and effective approach employing directly inexpensive and readily available TiCl4 in the route closely related to low-temperature soft-chemistry methods. In the method, aerosol of hydrated titania in submicron water droplets was obtained directly in an experimental setup using controllable hydrolysis TiCl4 vapors in aerosols of various aqueous solution of organic and inorganic compounds; thus formed mist was decomposed in a hot zone of a tubular furnace with controlled temperature of 500-11000C in air or oxygen. It allows to control composition and properties of thus obtained materials, easily introduce dopants, influence on morphology, specific surface area etc. Moreover all the process are in fact united in one experimental cycle. Using solutions of block copolymer, urea, H2O2 aqueous solutions, we can tune porosity, doping and then the photocatalytic activity of the obtained titania.

The obtained titania particles were found to have a spherical shape with a diameter ranging from 50 to 2000 nm and a complex surface structure. In the case of precursors containing organic or inorganic gas-forming component, porous particles were obtained. Using urea solution has resulted to nitrogen-doped TiO2, adding H2O2 to the hydrolyzing solution has demonstrated a drastic change of titania morphology. All the samples produced at temperatures above 600oC possessed an anatase structure and a different degree of crystallinity, then an amount of rutile becomes higher with a temperature increase.

All the samples obtained were analyzed with XRD, REM, TEM, nitrogen sorption (surface area analysis), DTA, TGA, IR and UV-vis spectroscopy, ESR.

 

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Related papers

Presentation: Poster at E-MRS Fall Meeting 2009, Symposium H, by Alexey Tarasov
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-24 18:26
Revised:   2009-06-07 00:48