| AVS 58th Annual International Symposium and Exhibition | |
| Surface Science Division | Wednesday Sessions |
| Session SS1-WeM |
| Session: | Atomistic Control of Structure & Evolution |
| Presenter: | Jonathan Brauer, University of Alabama |
| Authors: | J.I. Brauer, University of Alabama G.J. Szulczewski, University of Alabama |
| Correspondent: | Click to Email |
A two-step strategy to improve the photocatalytic activity of titania is reported. First, nitrogen doped titanium dioxide, denoted N-TiO2, has been synthesized by sol-gel methods to increase the absorption of visible radiation. Second, surface hydroxyl groups of the as-synthesized powders are replaced with fluoride ions. The two-step strategy gives independent control of “bulk” doping and surface modification. The as-synthesized and annealed powders were characterized by x-ray photoelectron spectroscopy, x-ray diffraction, diffuse reflection UV/Vis spectroscopy, IR spectroscopy, and scanning electron microscopy. Surface fluorination has two important consequences: it lowers the temperature to crystallize the as-synthesized powders into the photoactive anatase phase and improves the retention of nitrogen-dopants upon annealing. The photoactivity of the titania powders were characterized by assessing the ability to degrade aqueous solutions of methylene blue, a common dye molecule, with visible radiation greater than 420 nm. The photodegradation experiments show that the rate of methylene blue decomposition follows the trend: F, N-doped TiO2 > N-TiO2 > undoped TiO2. A mechanism to explain the observed effects will be presented.