Photocatalytic remediation of indoor pollution by transparent TiO2 films

Transparent, mechanically robust TiO2 films obtained by an innovative electrochemically assisted procedure are presented as effective photocatalysts for environmental remediation and self-cleaning. The film morphology and optical properties were investigated by scanning electron microscopy (SEM), and UV-vis spectroscopy. Mechanical tests (Wolff Wilborn hardness and adhesion tests) proved the high robustness of the layer. The film thickness could be modulated by varying the number of deposited layers (from 1 to 5) without altering the film transparency. A fast light-induced superhydrophilicity is observed even under solar irradiation. The photocatalytic remediation activity of the films was tested under UV and solar irradiation towards two different systems: the gas phase degradation of volatile organic compounds, VOCs (ethanol and acetaldehyde) and the degradation of dry stains of long chain organic molecules (siloxanes) adsorbed at the film surface to simulate the staining by fingerprints/oily liquids. The titania layers showed excellent photocatalytic activity in both tested systems under UV and simulated solar irradiation. The photocatalyst deactivation upon repeated degradation tests was observed to be very limited. The presented stable and transparent TiO2 layers represent promising materials for photocatalytic windows and coatings.