Physical Electronics Dept.

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By

Dr. Ariel Kleiman
(Universidad de Buenos Aires)

(currently post-doctoral fellow in the Electrical Discharge and Plasma Lab, Tel Aviv University)

Characterization of photocatalytic TiO₂ films grown by

unfiltered vacuum arc deposition

Titanium dioxide has been the subject of numerous investigations due to its outstanding chemical and physical properties. One of the most active research fields on TiO₂ is its use as photocatalyst for degradation of pollutants in water, anatase being the most active photocatalytic phase among the different crystalline structures of this compound. Anatase thin films have been prepared by several techniques. Among them, vacuum arc deposition (VAD) is characterized by high deposition rate and high adhesion of the coatings to the substrate. The structure of films produced by VAD depends significantly on the substrate temperature during the deposition process.

Anatase TiO₂ thin films were grown by VAD on glass substrates at 400 ºC and at room temperature; the latter being annealed after deposition in order to promote crystallization. Structure, morphology and optical properties of both types of films were analyzed. Adhesion tests were performed as well, the samples showing high adherence to the substrate.

Films were also studied by X-ray reflectometry (XRR), a powerful technique that allows determining thickness, density and roughness from single or multilayered films. Experimental XRR patterns were well fitted by simulated curves considering a very thin layer of adsorbed H₂O over a single TiO₂ film.

In addition, the photocatalytic activity and the kinetic behavior of the films were studied. The activity was evaluated through the efficiency in UV-assisted reduction of Cr(VI), a highly toxic pollutant very common in industrial wastewater.