Photocatalytic efficiency of TiO2 films immobilized by annealing on glassy support as a function of material mass loading

Abstract

The impact on the structure and photocatalytic behavior of annealed TiO2 films at 450°C on glassy support prepared by the doctor blade method with different amounts of material loadings was evaluated. Raman, SEM-EDS, and X-ray analyses indicated that higher material loading only increased the thickness of the annealed TiO2 films, but not their surface roughness, which remained almost constant at 290 ± 13 nm. Quantum yields for photocatalytic generation of ROS (HO• or O2•−) and degradation of model organic pollutants such as rhodamine B and methylene blue were also determined under different illumination configurations up to three photodegradation cycles without loss of photocatalytic activity. A marked bell-shaped dependence with mass loading was observed, with the film with approximately 0.1 mg TiO2.cm−2 and 1 μm thickness providing the highest efficiency. Under these conditions, increased light penetration through the film occurs through various internal reflections, which enhances the excitation of the TiO2 particles on the surface of the material in contact with the aqueous solution. Therefore, the results highlight the intricate interplay between material loading and film thickness with excitation light to achieve optimal photocatalytic activity of immobilized TiO2, a factor that can be considered in the rational design of efficient photoreactors.