Photocatalytic Activity of Sol−Gel TiO₂ Thin Films on Various Kinds of Glass Substrates:  The Effects of Na⁺ and Primary Particle Size

Abstract

To study the effects of ions diffused from the glass substrate on TiO2 photocatalysis, TiO2 thin films were prepared on different kinds of glass substrates at different heating temperatures. The TiO2 films were characterized using X-ray photoemission spectroscopy (XPS), X-ray diffraction (XRD), ellipsometry, and absorption spectroscopy. The photocatalytic activities of the TiO2 thin films were evaluated using the degradation reaction of trichloroethylene (TCE). Diffused ions such as Na+ and Si4+ raised the anatase formation temperature and increased the particle size of TiO2 thin films (r c). The photocatalytic activity of the thin films largely depended on the particle size of TiO2; the reciprocal number of the half-life of the TCE degradation, t 1/2 -1, was roughly proportional to r c -1.8. The conventional recombination center hypothesis for the Na+ ions might not hold for the sol−gel TiO2 films.

Mechanistic Studies of the Photocatalytic Oxidation of Trichloroethylene with Visible‐Light‐Driven N‐Doped TiO2 Photocatalysts

“…[22][23][24] There have been a number of studies of the photocatalytic oxidation of TCE with TiO 2 under UV irradiation, [1,25,26] and a practical reaction plant has also been reported.…”

Nanomechanical Properties of TiO2 Granular Thin Films

“…Although it was known from the early years of research on photocatalysts that Na diffusion from substrate has an adverse effect on TiO 2 photocatalytic properties, there are few quantitative reported studies. Nam and coworkers studied the effect of Na diffusion on photocatalytic properties of TiO 2 sol-gel films (33) and found that photocatalytic activity is increased with temperature due to the constructive effect of Na on the anatase crystal formation. They also noted that sodium ions cannot be regarded as recombination centers.…”

Photocatalytic TiO2 and Doped TiO2 Coatings to Improve the Hygiene of Surfaces Used in Food and Beverage Processing—A Study of the Physical and Chemical Resistance of the Coatings

“…Photocatalytic performance is influenced by film characteristics including; composition, bulk and surface structure and nanostructure, atomic to nanoscale roughness, hydroxyl concentration, and impurity concentration (e.g., Fe and Cr) [22][23][24][25].…”