Mesoporous silica (SBA-15 with the BJH pore size of 8 nm) containing anatase nanoparticles in the pore with two different titania contents (28 and 65 mass%), which were prepared by the infiltration of the amorphous precursor derived from tetraisopropyl orthotitanate into the pore, were heat treated in air to investigate the structural changes (both mesostructure of the SBA-15 and the phase and size of the anatase in the pore). The mesostructure of the mesoporous silica and the particle size of anatase unchanged by the heat treatment up to 800 °C. The heat treatment at the temperature higher than 1000 °C resulted in the collapse of the mesostructure and the growth of anatase nanoparticles as well as the transformation to rutile, while the transformation of anatase to rutile was suppressed especially for the sample with the lower titania content (28 mass%). The resulting mesoporous silica-anatase hybrids exhibited higher benzene adsorption capacity (adsorption from water) over those heated at lower temperature, probably due to the dehydroxylation of the silanol group on the pore surface. The photocatalytic decomposition of benzene in water by the present hybrid heated at 1100 °C was efficient as that by P25, a benchmark photocatalyst.

The formation of BiOX (X=Br and Cl) nanoparticles in a mesoporous silica (SBA-15) was found by the reaction of the infiltrated bismuth oxo species with HX vapor at room temperature....

Rutile nanorods (single nanorods and connected nanorods) with diameter similar to the pore size of the template (cylindrical mesopore of SBA-15 with a pore diameter of 8 nm) are prepared by infiltration of the partially hydrolyzed titanium alkoxide and the subsequent in situ crystallization in the mesopore by reaction with HCl vapor at room temperature. Morphological variation is achieved by varying the loading amount of the titanium dioxide precursor in the mesoporous silica. The crystallization is followed by Raman spectra and X-ray diffraction patterns. The single rutile nanorods with the diameter of 5 nm and the connected rutile nanorods with the diameter of 7 nm are successfully collected by dissolving the silica template (SBA-15) using an aqueous solution of sodium hydroxide. Both supported and isolated rutile nanorods are active for hydrogen evolution from an aqueous methanol solution by ultraviolet (UV) irradiation.

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