Photocatalytic activity of TiO2 films immobilized on aluminum foam by atomic layer deposition technique
Résumé
The aim of the this work was to study feasibility of titanium dioxide thin films prepared by atomic layer deposition (ALD) technique on aluminum foam substrates for photocatalysis and compare performance of thin films with commercially available AEROXIDE® TiO2. Formic acid and phenol photocatalytic decomposition was monitored using high-pressure liquid chromatography (HPLC). The morphology and thickness of TiO2 films were characterized by scanning electron microscopy (SEM) and their structure was determined by X-ray diffraction (XRD). Surface of the thin films was characterized with Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The amount of TiO2 deposited on aluminum foam was measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). It was observed that initial rates of formic acid and phenol degradation were 0.007 and 0.001 mmol L−1 min−1, respectively. The apparent quantum yields for formic acid using immobilized and reference TiO2 powder (AEROXIDE® TiO2 P25, Evonik) were 2.2 and 2.7%, correspondingly. While for phenol apparent quantum yield was equal to 0.4% when TiO2 thin film was used and 0.7% in the case of reference powder. A decrease of the photocatalytic activity of TiO2 films deposited on aluminum foam was observed after the first cycle for both model compounds. It was suggested from this study that suppression of activity occurs due to detachment of TiO2 from the surface of thin film.