Enhance photocatalysis of TiO2 and ZnO ceramics by addition of fused silica as a UV guiding medium

We report a facile method to prepare porous TiO 2 and ZnO photo-catalytic ceramics in which colloidal silica was added to yield nano fused silica (FS). The colloidal silica forms continuous media within the porous ceramic structure, and when calcined at 550   °C, it converted to fused silica phase which is an excellent UV wave-guiding material. With light wave guiding effect of FS and capillary effect of reaction solution in the porous channels, the photo-catalytic reactions could occur at the vast active sites at interface inside the porous bulks, as well as at the external surfaces. Photo-catalysis experiments and kinetics were investigated and analyzed. The photo-catalytic efficiencies tested for methylene blue were enhanced by a factor of 4.1 for TiO 2 /FS system and, astonishingly, by a factor of 34.6 for ZnO/FS system, when compared with pure TiO 2 and ZnO under identical testing conditions. A model of UV-waveguide ceramic systems was proposed and discussed. This study proposes a practical approach to construct UV-waveguide porous structures, of which the principle is also potentially applicable to other types of photo-catalytic materials, including visible light active photo-catalysts.