SBA-15:TiO2 nanocomposites: II. Direct and post-synthesis using acetylacetone

Nanosized titanium dioxide (TiO2) is used in different applications that require a specific crystalline structure. In this work, SBA-15:TiO2 nanocomposites (80 mol% Si and 20 mol% Ti) were prepared using two different synthesis routes (direct and post-synthesis), with and without acetylacetone and a modified hydrothermal route (M). The small angle X-ray diffraction data showed that all nanocomposites are ordered mesoporous materials. N-2 adsorption-desorption analysis showed that the materials exhibit a narrow pore size distribution with mean pore diameters up to 9.9 nm, high surface areas up to 810 m(2) g(-1) and large pore volumes up to 1.3 cm(3) g(-1). The analysis of the morphology by scanning electron microscopy (SEM) revealed different particle shapes due to the inclusion of Ti together with the Si source in the direct synthesis route. The characterization by X-ray diffraction revealed that the presence of acetylacetone and the M route in the direct synthesis method favored the formation of the rutile phase (>90%). Additionally, the posterior inclusion of Ti (post-synthesis) favored the formation of single phase anatase (100%). In addition, the SEM images showed that the silica particle size is about 1 mu m, thus being biologically safe and making the composite a very promising photoprotector. (C) 2016 Elsevier Inc. All rights reserved.