|Reference : Aqueous and non-aqueous sol-gel preparation of TiO2 films for the photocatalytic oxidati...|
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Physical, chemical, mathematical & earth Sciences : Chemistry
Engineering, computing & technology : Materials science & engineering
|Aqueous and non-aqueous sol-gel preparation of TiO2 films for the photocatalytic oxidation of ethanol in air|
|Cimieri, Iolanda [Ghent University > Department of Solid State Sciences > LumiLab > >]|
|Poelman, Hilde [Ghent University > Department of Chemical Engineering > > >]|
|Lambert, Stéphanie [Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Génie catalytique >]|
|Heinrichs, Benoît [Université de Liège - ULg > Département de chimie appliquée > Génie chimique - Nanomatériaux et interfaces >]|
|Poelman, Dirk [Ghent University > Department of Solid State Sciences > LumiLab > >]|
|International Symposium on Advanced Complex Inorganic Nanomaterials, ACIN 2011|
|11-14 September 2011|
|[en] One of the most versatile methods to prepare TiO2 fine powders and films is the sol-gel technique. It offers many advantages, among which the possibility to control the stoichiometry, work in mild and ambient atmospheric conditions and achieve high purity and homogeneity of the final product.
Stable TiO2 sols were synthesized by an aqueous sol-gel process using titanium tetraisopropoxide (TTIP) as precursor and nitric acid in water as hydrolyzing agent.
The aim of the present study was to investigate the influence of different solvents and different amounts of HNO3 on the photocatalytic activity of TiO2 in the breakdown of ethanol (EtOH) as VOC molecule under UV and visible light. In particular, ethanol, isopropanol and butanol were used as solvents and two different molar ratios of HNO3 with respect to TTIP (0.25 and 0.5 respectively) were used. Their effect was investigated with regard to the photocatalytic properties of the films obtained by spin coating on sodium free glass  and heat treated at 450°C in air.
The microstructure, optical and morphological properties of the films were investigated using SEM, UV-Vis spectroscopy and ellipsometry. The nature of the crystalline phases was ascertained by X-ray diffraction and the surface area of the powders was measured by N2 adsorption.
The porous TiO2 films obtained show quite good photocatalytic activity for the degradation of EtOH compared to titania films prepared using P25 Degussa as shown in Fig. 1. Further the photocatalytic properties of the thin films obtained by aqueous sol-gel method were compared with the activity of films prepared using the same titanium precursor by a non-aqueous sol-gel process, in which the hydrolysis is initialized by esterification reaction between acetic acid and alcohol.
(Fig.1. EtOH degradation for P25 (green), non aqueous sol (purple) and aqueous sols prepared using ethanol as solvent and HNO3 in molar ratios 0.25(blue) and 0.50(red))
 H. Tomaszewski, K. Eufinger, H. Poelman, D. Poelman, R. De Gryse, P.F.Smet, G.B. Marin, Int. J. Photoenergy 8, 1 (2007)
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