A sol–gel dip/spin coating method to prepare titanium oxide films

• A dip/spin coating method to prepare titanium oxide films was proposed.
• The films were prepared by the lower side of the support contacting the sol.
• The crystal grains in the films were tiny and uniform with a unique structure.
• The films demonstrated excellent photocatalytic activity.

A dip/spin coating method for the preparation of titanium oxide films was proposed. Instead of placing an oxide sol on top of a substrate surface, the dip/spin coating was accomplished on the lower surface of the substrate where gravitational force exerted on the colloidal particles during spreading under a centrifugal force. The resulting TiO2 films were compared to those prepared using the conventional spin-coating and dip-coating methods. All the films were found to be composed primarily of anatase with a small amount of brookite. Compared to the films prepared using the conventional spin-coating and dip-coating methods, the TiO2 films fabricated using the dip/spin method had small and uniform grains with a unique structure, resulting in an increased photocatalytic activity when tested for degradation of methyl orange under UV irradiation.