Photocatalytic removal of ethanol and acetaldehyde by N-promoted TiO2 films: the role of the different nitrogen sources

Pure and N-doped TiO2 nanoparticles are obtained by a combination of wet and thermal procedures, starting from TiCl3 and alkoxide precursors; the N-source is both inorganic (NH3) and organic (triethylamine). Samples are characterized for their bulk, surface, optical and magnetic properties. Ab initio calculations of the electronic properties of the doped samples are performed. Sample thin films are tested for their photocatalytic activity, under UV and simulated solar irradiation, with respect to air pollutants ethanol and acetaldehyde. Both the disappearance of the molecule itself and the complete mineralization (CO2) are followed during the reaction time. FTIR/ATR analyses are performed on samples withdrawn during the course of the reaction to identify reaction intermediates. In the case of acetaldehyde, photocatalytic tests are also performed under visible light (λ > 400 nm). The photoactivity sequences of the N-doped samples under the different irradiation sources are discussed with reference to their surface/bulk properties, light absorption features, nature and amount of paramagnetic species.