Comparison of Different Characteristics of Tio₂ Films And Their Photocatalytic Properties

Urh Černigoj, Urška Lavrenčič Štangar, Polonca Trebše, Primož Rebernik Ribič

Nova Gorica Polytechnic, P.O.B. 301, 5001-Nova Gorica, Slovenia

Absract
TiO₂ is known as a photocatalyst and is often utilized for the oxidative mineralisation of pollutants. The correlation between the thickness, mass, surface topography and the type of support of the titania films and their photocatalytic activities were studied in this work. TiO₂ films were deposited on two different glass supports via sol-gel methods. Film thicknesses and weights have been measured. Film surfaces were characterized by AFM measurements. The presence of surfactant in the sol and the type of support influence the morphology of film’s surface and the UV absorption characteristics. The addition of surfactants also increases the thicknesses of calcined films. For the photocatalytic experiments the titania film was immersed in an aqueous solution of Plasmocorinth B. Sodium glass support reduces the photocatalytic activity compared to protected glass support with a thin silica layer. The photocatalytic activity was found to increase with the number of TiO₂ layers in all cases. However, when comparing different films with the same number of TiO₂ layers, the addition of Pluronic F-127 surfactant in the sol was shown to have a significant positive effect on the photocatalytic activity. The use of this surfactant results in thicker and heavier films and consequently in more efficient absorption of UVA light.

Keywords: TiO₂ thin films, UV-Vis, surface morphology, photocatalysis, azo dye