Sol–gel preparation and properties study of TiO₂ thin film for photocatalytic reduction of chromium(VI) in photocatalysis process

Abstract

In this paper, a sol–gel technique with dip coating method is used to prepare photocatalytic TiO₂ thin films immobilized on glass plates. The structure and morphology of thin films are characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The structural characterization of this film shows that the titanium oxide anatase phase is predominant at 400–700 °C. The appearance of the rutile phase depends mainly on the number of coating cycles. For example, the rutile phase appeared at 600 °C with 5 coating cycles, however, it disappeared fromTiO₂ crystalline after 8 coating cycles. The obtained thin films from each preparation condition were employed in experiment of photoreduction of chromium. The results show that the Chromium(VI) is successfully removed from aqueous in photocatalysis system using the obtained thin film with high portions of anatase phase. The photoactivity of the prepared TiO₂ thin films exhibits a comparable efficiency with TiO₂ powder, Degussa P-25.

Key Words:

• Titanium dioxide
• Thin film
• TiO₂
• Photocatalysis
• Chromium
• Heavy metal
• Sol–gel