Controlled Design of Mesostructured Titania Based Materials
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Controlled Design of Mesostructured Titania Based Materials G.J. de A.A. Soler-Illia, D. Grosso, E. L. Crepaldi, F. Cagnol and C. Sanchez Laboratoire de Chimie de la Matière Condensée, Université Pierre et Marie Curie, 4 Place Jussieu, Tour 54 5e, 75252, Paris Cedex 05, France. e-mail : [email protected] ABSTRACT Mesostructured TiO2-surfactant hybrid xerogels and thin films are prepared by EvaporationInduced Self Assembly (EISA). These organized structures are reproducibly formed through cooperative self-assembly between hydrophilic Ti-oxo species and a micellar template after selective solvent evaporation from ethanol/HCl/H2O media. The construction of these networks is tailored by tuning the hydrolysis-condensation of the metallic cations with the self-assembly of the organic counterparts (“hydrophilic matching” approach). The hybrids present hexagonal mesostructure (p6m). The formation kinetics of the mesophase is followed by SAXS, interferometry and mass spectrometry (MS) analysis of the vapor phase. An adequate thermal treatment of the organized hybrids leads to high surface (150-400m2 g–1) phosphorus-free mesoporous titania films or powders, with walls containing anatase nanocrystallites. This approach can be successfully extended to other non-silicate based meso-structured materials. INTRODUCTION Mesostructured hybrid organic-inorganic phases have a central role in "Organised matter chemistry", a quickly developing area at the crossroads of materials chemistry, physics and biology.[1] While much progress has been attained in silica-based materials,[2] interest and positive results in transition metal (TM) oxide-based systems is increasing [3]. The control of the high hydrolysis-condensation reactivity of TM by retarding condensation is essential for tuning the process of inorganic framework formation with the organization process of the organic template. In this work, we will focus on the development of synthesis methods for high surface area mesostructured TiO2 based materials, which are indeed attractive in view of controlled delivery, (photo)catalytic or energy conversion applications. Evaporation-Induced Self Assembly (EISA)[4] is an interesting synthesis route to prepare TiO2-based mesostructures. In the dilute initial solutions, no micellar aggregates are present (i.e., ctemplate 80°C. As in the case of thin films, the balance between solvent evaporation versus condensation of the inorganic phase is crucial for the phase segregation at the mesoscale. In very dilute and water-rich Ti/CTAB systems (s = 0.2, p=10, h=90, [EtOH]/[Ti] = 70), the best organization is reached at 50-60°C. In both cases, the temperature effect on condensation takes over the enhanced evaporation rate [5]. Q7.3.4
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Figure 3 : a) Solvent release evolution along the formation of a T
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