Abstract
This paper deals with the effect of Cr content on photocatalytic activity of TiO2 thin films deposited on quartz and intrinsic silicon substrates by using the RF magnetron co-sputtering process. Some physical investigations on such sputtered films were made by means of X-ray Diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy as well as UV-Vis-IR absorption techniques. The heat treatment under oxygen atmosphere at 550°C reveals that the crystalline structure of TiO2: Cr depends on Cr content. Anatase-to-rutile phase transformation occurs at a Cr content of about 7%. On the other hand, the band gap energy value of annealed TiO2: Cr films varies in terms of Cr doping and a transition around 7% of Cr is accrued. The photocatalytic activity of undoped and doped TiO2 films was evaluated by photo-degrading of the amido black under UV light irradiation. Modification of the chemical structure of titanium dioxide by Cr doping allows moving the photocatalytic activity of titanium dioxide towards visible light. The results indicate that films doped with 2% Cr exhibit the highest UV and visible light photocatalytic activity.
Highlights
TiO2 belonging to large band gap semiconductor oxides family has interesting properties
In our previous work we have reported that as Cr concentration in Cr-doped TiO2 films varies between 2% and 17% the PCr increases from 8 to 150 W [21]
The room-temperature deposited TiO2: Cr films are mainly amorphous containing some TiO2 nanocrystallites, of which increases with the Cr content
Summary
TiO2 belonging to large band gap semiconductor oxides family has interesting properties. TiO2 thin films have been tested in various electronic and optoelectronic devices such as: photovoltaic solar cells [2], gas sensors [3], electrochromic displays and photocatalyst [4] Thin films of this oxide have been obtained by diffrent vacuum techniques especially via chemical vapor deposition [5], pulsed laser deposition [6] and sputtering [7]. To shift the response of photocatalytic activity of TiO2 from ultraviolet (UV) to visible domain, various works have been carried to tune the band gap of TiO2 for the efficient absorption of the visible light. Among these studies, there are few attempts on the photocatalytic activity using Cr doped TiO2 thin films [10]-[13]
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