Self-Cleaning Test of Doped Anatase-Coated Glass Plates

Doped anatase thin films on glass were deposited by ultra-spinning from titanium isopropoxide-based sol-gels. To test the self-cleaning properties of anatase-coated glass, crystalline fluoranthene, a polycyclic aromatic compound, was sprayed over the glass and then irradiated using a 365 nm UV source. This anthropogenic contaminant was removed until 98 wt.% at 140 h of irradiation time with the 2 wt.% zinc ferrite-doped anatase film. The fluoranthene proportion degraded on anatase-free glass was much lower than with anatase coating giving only 12% for an irradiation time of 140 h. In this form, the coated-glass transparency was recovered almost totally at this irradiation time for the doped anatase film mentioned, which did not occur with anatase-free glass, even after more than 400 h of UV irradiation. A correlation was found between the total weight losses of the solid compound and the intensity of the Raman vibration at 671 cm-1 during photocatalytic degradation. After 140 h of irradiation, while the presence of fluoranthene is not detected by Raman spectroscopy, glass plate presented ultra-thin zones of degradation products. Thus, the removal of these intermediate products deposited on glass was directly measured by means of weight difference. The self-cleaning properties of doped anatase coating on window glass could have a positive influence on outdoor and indoor air quality. In this work, degradation mechanisms and intermediate products were not discussed or identified.