Heterostructural transformation of mesoporous silica-titania hybrids

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 degrees C. The heat treatment at the temperature higher than 1000 degrees 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 degrees C was efficient as that by P25, a benchmark photocatalyst.

Automated summary

The research investigated the structural changes of mesoporous silica-anatase hybrids containing different titania contents after heat treatment, revealing that heat treatment can cause the collapse of mesostructure and phase transformation of anatase. However, the resulting hybrids showed high efficiency in photocatalytic decomposition of benzene even after heat treatment.