title: Hierarchically organized silica-titania monoliths prepared under purely aqueous conditions.
abstract: Hierarchically organized silica-titania monoliths were synthesized under purely aqueous conditions by applying a new ethylene glycol-modified single-source precursor, such as 3-[3-{tris(2-hydroxyethoxy)silyl}propyl]acetylacetone coordinated to a titanium center. The influence of the silicon- and titanium-containing single-source precursor, the novel glycolated organofunctional silane, and the addition of tetrakis(2-hydroxyethyl)orthosilicate on the formation of the final porous network was investigated by SEM, TEM, nitrogen sorption, and SAXS/WAXS. In situ SAXS measurements were performed to obtain insight into the development of the mesoporous network during sol-gel transition. IR-ATR, UV/Vis, XPS, and XAFS measurements showed that up to a Si/Ti ratio of 35:1, well-dispersed titanium centers in a macro-/mesoporous SiO2 network with a specific surface area of up to 582 m(2)  g(-1) were obtained. An increase in Ti content resulted in a decrease in specific surface area and a loss of the cellular character of the macroporous network. With a 1:1 Si/Ti ratio, silica-titania powders with circa 100 m(2)  g(-1) and anatase domains within the SiO2 matrix were obtained.
authors.affiliation: Materials Chemistry, Paris-Lodron University Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria), Fax: (+43) 662-8044-622.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Flaig
authors.forename: Johanna
authors.initials: J
authors.lastname: Akbarzadeh
authors.forename: Paolo
authors.initials: P
authors.lastname: Dolcet
authors.forename: Silvia
authors.initials: S
authors.lastname: Gross
authors.forename: Herwig
authors.initials: H
authors.lastname: Peterlik
authors.forename: Nicola
authors.initials: N
authors.lastname: Hüsing
keywords: mixed oxides; porous monoliths; silica; sol-gel process; titania