Reactive Black-5 Photodegradation by TiO₂ Thin Films Prepared by Ultrasonic Spray

Structural, optical, textural and photochemical properties of transparent TiO₂ thin films were investigated using XRD, AFM and DR-UV-Vis spectroscopy. TiO₂ films were obtained by the ultrasonic spray pyrolysis (USP) deposit technique, using corning glass as substrate and a Titanium-Acetyl-acetonate in N,N-Dimethylformamide solution as precursor. XRD patterns depicted the presence of nanostructured materials with poor crystallinity and by diffuse reflectance spectroscopy was measured the absorption profile and calculated the band gap energy of the TiO₂ thin films. As the layer thickness diminished, the absorption edge showed a blue shift and the band gap energy was increased. AFM studies allowed determination of irregular thin coating with different morphologies and the presence of micropores. The photocatalytic behavior was evaluated employing the Reactive Black-5 degradation as model reaction. The reaction progress was monitored following the absorbance at 315 and 597 nm of the corresponding UV-Vis absorption spectra. According with the catalytic tests, it was found that the best degradation was achieved with the film prepared at 450 C during 6 minutes.