TiO2 thin films for the photodegradation of TCE in air: Optimization of the sol-gel preparation method

Porous TiO2-anatase thin films were prepared by the sol–gel route and used for the study of the influence of structural properties in their photocatalytic activity. 

Sols were prepared by using titanium isopropoxide with two types of modifier ligands, namely acetic acid and acetyl acetone, and pore generating agents such as polyethylene glycol, pluronic F-127 and polyethylene glycol hexadecyl ether (Brij 58). The photocatalytic activity for the degradation of trichloroethylene in air was evaluated under ultraviolet irradiation at different gas flows and water vapour contents. The photocatalytic activity depends on the nature of the pore generating agent which influences the TiO2 crystallite size and the textural properties of the final material. The samples obtained by using acetic acid as the modifier ligand and either Brij 58 or PEG as the pore generating agent exhibited the best photocatalytic behaviour even in the presence of high quantities of water vapour. The direct trichloroethylene oxidation pathway to CO2 is favoured at low water vapour contents, but an important generation of COCl2 is observed even at low water partial pressures.