Synthesis of highly ordered macro-mesoporous anatase TiO2 film with high photocatalytic activity

Highly ordered macro-mesoporous anatase TiO2 film was synthesized by sol–gel method in an acidic medium, using polystyrene (PS) colloidal crystal and triblock copolymer P123 (EO20PO70EO20) as dual templating. The resulting film was characterized by Raman spectroscopy, X-ray diffraction (XRD), N2 adsorption–desorption analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocatalytic activity of the porous TiO2 film was evaluated by characterizing its photocatalytic effect on the photodegradation process of Rhodamine B (RhB). The results reveal that the bimodal porous material is in anatase phase, and the three-dimensionally ordered macroporous walls are composed of highly ordered mesopores. The average size of the mesopores and the BET surface area are 6.70 nm and 143.37 m2 g−1, respectively. The obtained TiO2 film shows a higher photocatalytic activity than commercial photocatalyst Degussa P25.

The highly ordered macro-mesoporous anatase TiO2 film was successfully prepared by using PS colloidal crystal as macrotemplate and the triblock copolymer P123 as a mesostructure-directing agent in a sol–gel reaction. The highly crystalline anatase phase and bimodally well-ordered macro-mesoporous structures were preserved after calcination at 400 °C for 3 h. In comparison with commercial photocatalyst Degussa P25, the TiO2 film exhibited better photocatalytic activity in the photodegradation of RhB in aqueous suspensions.Figure optionsDownload as PowerPoint slideResearch highlights
► In this paper, highly ordered macro-mesoporous anatase TiO2 film was successfully prepared by using dual templating of polystyrene (PS) colloidal crystal and triblock copolymer P123.
► The former was employed to produce controllable ordered macropores and the latter to produce highly ordered mesopores.
► Meanwhile, several improvements were made in this study: in the sol–gel process, the introduction of hydrochloric acid, nonaqueous media (ethanol) and acetylacetone chelator can help to control the fast hydrolysis and condensation rates of titanium alkoxides; controlling the relative humidity (70–75%) can be favourable for the formation of highly ordered pore structures; through controlling the heating conditions, both the highly crystalline anatase phase and perfect and intact macro-mesoporous structures (without the collapse of order mesoporous structures) were obtained.
► Finally, the resultant TiO2 film showed a higher photocatalytic activity than commercial photocatalyst Degussa P25 because of its bimodally ordered macro-mesoporous structures and highly crystalline anatase phase.