Self-Cleaning Test of Doped TiO2-Coated Glass Plates under Solar Exposure

Photocatalytic films of TiO2 doped with metal oxides, ZnFe2O4, ZnO, and CuO, were formed on glass plates by the ultraspinning method from Ti(IV) isopropoxide-based sol−gels. To test the self-cleaning properties of TiO2 films on glass, a layer of crystalline fluoranthene, a polycyclic aromatic compound, was placed over the glass by spraying and then exposing it to solar irradiation. The covering of fluoranthene on the 1 wt % metal oxide-doped anatase films was degraded nearly to 100% at 20 h of exposure time. Thus, the coated-glass transparency was recovered totally between 35 and 52 h of exposure time for the doped anatase film, which did not occur with anatase on glass, even after more than 85 h of solar irradiation. For some samples, a correlation was found between the weight losses of the solid compound and the intensity of the Raman vibration at 671 cm−1 during photocatalytic degradation. After 20 h of solar exposure, while the presence of fluoranthene was not detected by Raman spectroscopy, some glas...