Synthesis of oxynitrides and nitrogen-doped titania and FTIR studies of thermal and photooxidation of acetone on titania

The thermal degradation of acetone on titania (Degussa P25) has been studied. FTIR was used to monitor the loss of acetone and the production of carbon dioxide. By using 13C isotopically-labeled acetone, this study shows that the carbonyl carbon of acetone is oxidized more efficiently than the methyl carbon of acetone. Carbon-containing surface-bound intermediates are implicated in the reaction mechanism leading to carbon dioxide production. Combining these results, a mechanism is proposed in which acetate and formate are important intermediates in the thermal oxidation of acetone on titania.; Also in this work, two potential visible light photocatalysts, nitrogen-doped titania and tantalum-containing oxynitrides, are synthesized and studied for their visible light photoactivity. The nitrogen doped titania is prepared by nitrification in an ammonia flux at high temperature.; UV-Vis diffuse reflectance spectra show that doping with nitrogen can extend the absorption spectrum of titania into the visible light region. The oxynitrides are prepared by both induction heating and nitrification in an ammonia flux at high temperature. The UV-Vis diffuse reflectance spectra show that the bandgap of the oxynitrides can be tuned to move into the visible light region by changing the coordinated metal ion and the N content. Furthermore, these compounds show visible light photoactivity for the photocatalytic oxidation of acetone under visible light illumination (lambda > 420nm). However, their visible light photoactivity is limited. SEM and surface area experiments show that the low surface area resulting from the high temperature synthesis could contribute to this low photoactivity.