Effect of amorphous fluorinated coatings on photocatalytic properties of anodized titanium surfaces

Absorption and photocatalytic degradation of VOCs by perfluorinated ionomeric coating with TiO2 nanopowders for air purification

“…The former acted as inner hydrophobic fluorinated primer, in contact with glass, and the latter as outer photoactive layer. Both polymeric AD and AQ layers were chemically stable toward the degradation effects due to UV light and TiO2 photocatalytic activity [40].…”

“…The compatibility of fluorinated materials in the presence of TiO2 was also studied and perfluoropolymers resulted extraordinarily stable toward UV-activated TiO2 photodegradation [39]. In particular, amorphous perfluoropolymers showed the highest chemical stability and, due to their high UV transparency and high gas permeability, emerged as best candidate class of materials for the fabrication of TiO2-embedding matrices [40,41]. Recently, a multilayered perfluorinated coating based on amorphous and low-crystalline fluoropolymers with immobilized TiO2 was applied in a continuous photocatalytic apparatus for water remediation [42].…”

Photocatalytic activity of TiO2-embedded fluorinated transparent coating for oxidation of hydrosoluble pollutants in turbid suspensions

“…Direct oxidation at the hole site is usually favored in case of highly adsorbed substrates, while the degradation of weakly adsorbed pollutants takes place mainly through hydroxyl radical mediated oxidation [10][11][12][13]. Hence, the oxidation of organic compounds could be ascribed either to a direct reaction with the photogenerated holes, or to an indirect reaction with hydroxyl radicals or to a combination of the two [14,15]. The use of photocatalytic TiO 2 in suspension or slurry type reactors has been reported to be well performing especially because of the high surface area of the catalyst available for the treatment (average surface area: 95 m 2 /g for pure anatase; 55 m 2 /g for commercial TiO 2 ; 75% anatase, 25% rutile; 25 m 2 /g for pure rutile) [16][17][18].…”

“…The use of perfluoropolymers as coating materials for anodized titanium substrates allows an increase in surface washability, resistance to soiling [14] and gas phase permeability [19,20]. It is well known that soiling on TiO 2 thin layers (e.g., TiO 2 nanotubes by titanium anodizing) can easily deactivate the catalyst [21].…”

“…It is well known that soiling on TiO 2 thin layers (e.g., TiO 2 nanotubes by titanium anodizing) can easily deactivate the catalyst [21]. Perfluoropolymeric materials, due to the massive presence of highly stable C F bonds, as high as 544 kJ/mol [22], are characterized by thermal and chemical stability [22,23], in particular toward UV radiation and UV-activated TiO 2 [24], low surface energy and, if amorphous, also high transparency [14,25]. The interaction between the embedded TiO 2 catalyst and the aqueous polluted solution can be optimized by the use of ionomeric materials.…”