Clearly discernible rings of high photocatalytic activity, i.e. rings of activation, RoAs, are formed around Pt macro-sized (radius: ro 1 mm radius) Pt islands, i.e. Pt ‘dots’, deposited on TiO2 films, which have been covered with a visible pollutant, such as soot, or a dye, such as acid orange 7, AO7. The features of the RoA region appear very similar for soot or dye-covered films. Thus, the radius of the RoA region, ra, appears to depend weakly, if at all, on ro, and is typically 0.60-0.68 mm > ro. The rate of photocatalytic removal of the surface pollutant inside the RoA is uniform and significantly greater, i.e. ca. 3.2 - 5 x's, than that outside the RoA region. RoA region formation is observed for: (i) Pt dots which have been photodeposited or created through thermal reduction, (ii) Pt dots on sol-gel and commercial (paints and tiles) TiO2 films and (iii) Pd dots, but less clearly for Au dots. A simple mechanistic rationale for RoA region formation is presented and the potential importance of this feature, with regard to improving the performance of commercial photocatalytic films, is discussed briefly.
Ring Photocatalysis: Bands of Activation Surrounding Macro-sized ( 1 mm radius) Pt Islands Deposited on TiO2 Films
Student thesis: Doctoral Thesis › Doctor of PhilosophyFile