Photocatalytic activity of TiO2 thin films deposited by cathodic arc

In this work, the photocatalytic activity and the kinetic behavior of anatase TiO2 films deposited by cathodic arc (CA films) on glass substrates are reported and compared with those of TiO2 Degussa P-25 films obtained by dip-coating immersion (DC films). The mass density of films, determined by X-ray reflectometry was 20% lower for DC films compared with CA films, indicating a higher porosity of DC samples. The activity was evaluated from the efficiency to reduce Cr(VI) in the presence of EDTA. Although the response of CA films resulted lower compared with that of P-25 films of the same TiO2 content (e.g. 90% vs. 50% Cr(VI) reduction after 180 min irradiation for samples with 0.03 mg cm(-2) of TiO2), a fact associated to the lower porosity, adhesion properties of the new materials were much better. CA film photoactivity improved by increasing the coating thickness; after 180 min, a sample with 0.03 mg cm(-2) of TiO2 presented 50% of Cr(VI) reduction vs. 80% for a sample with 0.28 mg cm(-2). These photocatalysts, whose preparation is simple and affordable, are very promising to be used as immobilized materials in photoreactors for the treatment of pollutants in gaseous and aqueous systems. (C) 2010 Elsevier B.V. All rights reserved.