Preparation, characterization and applications of monolithic titania-silica aerogels

In this work, new monolithic titania-silica aerogel materials were developed and evaluated. It started with the synthesis using modified sol-gel processes to obtain crack-free monolithic aerogels with high surface area, mesoporosity and titania contents. Influence of various synthesis parameters on aerogel properties was investigated, including modifier, Ti-Si incorporation mode, prehydrolysis, supercritical drying and Ti/Si ratio. The aerogel monoliths were gas permeable, therefore, when air stream flowed through the aerogel matrix, airborne pollutants diffused and were degraded on the internal aerogel surface by photocatalytic oxidation. Titania-silica aerogels exhibited higher photocatalytic activity than Degussa P25. Photocatalytic oxidation of trichloroethylene was investigated in detail using in-situ FTIR technique. Study on indoor air cleaning applications showed the aerogel monoliths effectively captured aerosols and bioaerosols, rapidly killed bacteria spores and were able to degrade VOCs mixture in humid air, indicating a potential candidate of multi-functional air filter materials.