Bio-templated synthesis of hierarchically ordered macro-mesoporous anatase titanium dioxide flakes with high photocatalytic activity

Highly ordered macro-mesoporous anatase titanium dioxide (TiO2) flakes were synthesized by a sol-gel method in an acidic medium, using fresh natural rose (Rosa hybrida L.) petals and triblock copolymer P123 (EO20PO70EO20) as dual templates. The resulting flakes were characterized by Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption-desorption analysis. The results reveal that the bimodal porous material is in the anatase phase, and the three-dimensionally ordered macroporous walls are composed of highly ordered mesopores. The Brunauer-Emmett-Teller (BET) surface area and the average size of mesopores are 125.91 m(2) g(-1) and 4.79 nm, respectively. The photocatalytic activity of the porous TiO2 flakes was evaluated by photodegrading rhodamine B (RhB) under ultraviolet (UV) light. The obtained TiO2 flakes exhibited a slightly higher photocatalytic activity than commercial photocatalyst Degussa P25.