Porous titania-based composite materials and their high-throughput photocatalytic evaluation for environmental remediation

Semiconductor-mediated photocatalysis is a promising technology for environmental remediation. Among various materials, titania is a well-known photocatalyst, yet much improvement is still required to further improve its activity. This thesis presents some approaches used to optimize the photocatalytic activity of porous titania-based materials that are physically viable for practical operations. Specifically, the effect of the addition of nitrogen during synthesis and silver nanoparticles combined with various templating methods were examined. A high-throughput testing system based on parallelization and miniaturization of methylene blue photodegradation reactions was also developed to facilitate the photocatalytic evaluation in an efficient manner. Hierarchically porous, anatase titania thin films of varied thickness were fabricated by a one-pot, soft-templating technique combined with a phase separation route. The pore structure was readily tuned by adjusting the concentration of the polymeric components added during the sol-gel synthesis. Poly(vinylpyrrolidone) (PVP) altered the three dimensional pore structure, generating macroporous networks within the films. The highest photocatalytic activity under UV irradiation normalized by the accessible surface area was obtained by porous titania thin films prepared using 1:1:0 poly(ethylene glycol):PVP:F127. The addition of F127 did increase the overall photocatalytic activity, but lowered the activity per unit area because of obstructed light penetration. In order to effectively utilize the visible light, mesoporous anatase titania with nitrogen doping was prepared by a template-free, sol-gel synthesis route. The effect of calcination conditions and the type of titania precursor were investigated, highlighting their profound influence upon the adsorption and visible light activity. The titania crystallization in the presence of nitrogen was also studied using in situ synchrotron powder diffraction. The nitrogen modifi