Micro-morphological effects on the photocatalytic properties of TiO2 films immobilized onto glass slides

FIORELLA TULLI; CLAUDIO D. BORSARELLI; JESÚS M. N. MORALES; FAUSTINO E. MORÁN VIEYRA; ESTEBAN E. SALAS

Viña del Mar

Encuentro; XIV Encuentro Latinoamericano de Fotoquímica y Fotobiología; 2019

Comité organizador de XIV Encuentro Latinoamericano de Fotoquímica y Fotobiología

Titanium dioxide (TiO2) is the most popular semiconductor utilized in photocatalytic processes, including water-splitting and contaminant degradation.1 The low cost and toxicity, high thermal and chemical stability of TiO2 are still advantages for its use as photocatalyst applying different immobilization strategies, despite the requirement of using UVA illumination sources for photoexcitation of the conductive band (3.1 eV).In this report, we present a systematic study of the photocatalytic efficiency of TiO2 thin films prepared by the ?Doctor Blade? technique onto commercial microscope glass slides. For this purpose 1 g of commercial TiO2 powder (Degussa P25 or Hombikat) was homogenized with 100 µL of acetylacetone, 50 µL of sodium dodecyl sulfate (10 mg mL-1), and different amounts of polyethylene glycol (PEG 20000, 20-100 %w/w TiO2) and latter, were calcinated during 2 h at 450 °C. The immobilized TiO2 were characterized by UV-vis reflectance and ATR-FTIR spectroscopies as well as by optical transmission and fluorescence microscopy. All films were mechanically stable after immersion in a water bath with orbital agitation during 5 h, while the %PEG has no effect on the amount of TiO2 deposited. However, different micro-morphology patterns were observed as a function of the PEG composition. Also, the photocatalytic activity of the films were evaluated by irradiation with a germicidal lamp (λmax 365 nm) and monitoring both the bleaching of adsorbed xanthenic dye Rose Bengal (RB)2 and reaction of the pre-fluorescent probe coumarin (CM) with the photo-generated HO?, to form 7-hydroxicoumarin (7OH-CM), which shows fluorescence at 460 nm.3 The relative quantum yields of RB photobleaching and HO? generation are discussed as function of the surface micro-morphology of the TiO2 films.