Photoactivity of titanium dioxide films with controlled orientation.

摘要

Photocatalysis is being explored as a possible alternative to current disinfection treatment methods. Switching to photocatalysis could remove issues with disinfection byproducts and lower the operating costs. However, the activity of photocatalysts is too low to be used commercially. The most common photocatalyst is titanium dioxide, and while the activity of titanium dioxide is high when compared to other photocatalysts, improvements need to be made before commercialization. Increasing the activity of TiO 2 can be done in a variety of methods, but this dissertation will focus only on a single method.;Previous research has found that TiO2 has a range of activities based on the different phases and orientations. Many groups are focusing on growing crystals that are mainly covered with the most active facet. However, photocatalysis is about balancing reactions, and combining the most active oxidation site with poor reduction site will lower the activity. It is believe that by combining a site that is good for oxidation with a site that is good for reduction can outperform a catalyst with random orientations or even those with the expression of a single orientation.;Controlling the phase and orientation of the titanium dioxide will be done by depositing TiO2 onto patterned substrates. The patterns were created through block copolymer lithography,providing sub-50 nm features over the surface of the substrate. The pattern will then be expressed through the film, creating a film that has controlled texture based upon the size scale of the patterned surface. These films will then be characterized by measuring the photoactivity through methylene blue degradation experiments.;In addition to the textured films, an experiment was carried out in effort to help identify and quantify reactivity of different orientations of TiO 2. This was done by photodepositing metal ions onto different TiO 2 films and measuring the metal deposition over time. These experiments showed the range in activities for oxidation and reduction reactions for the phases and orientations tested.