Dual-template synthesis of mesoporous TiO2 nanotubes with structure-enhanced functional photocatalytic performance

Abstract Mesoporous TiO 2 nanotubes (m-TiO 2 -NTs) with outstanding photocatalytic performance have been successfully synthesized, for the first time, through a dual-template method. The dual-template method uses multi-walled carbon nanotube (CNT) as a hard template to control the morphology and cetyltrimethylammonium bromide (CTAB) as a soft template to form the mesoporous structure. The resulting m-TiO 2 -NTs are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), nitrogen adsorption-desorption and X-ray photoelectron spectroscopy (XPS). Rhodamine B (RhB) and dibutyl phthalate (DBP) are used as model pollutants to evaluate the photocatalytic properties of the new materials. The m-TiO 2 -NTs possess a multiple channel tubular structure and have higher specific surface area than TiO 2 nanoparticles (TiO 2 -NPs). These features result in significantly superior photocatalytic activity for photodegradation. Specifically, the reaction rate constant for the photodegradation of RhB is 9.8 times greater with m-TiO 2 -NTs than it is with TiO 2 -NPs. In the case of DBP, the rate constant is 7.7 times higher. Photocatalytic removal ratios of gaseous acetaldehyde (CH 3 CHO) and the generation of CO x (CO + CO 2 ) were detected to evaluate the decomposition ability of the materials, m-TiO 2 -NTs showed the best CH 3 CHO removal efficiency and the highest CO 2 selectivity. The active species of photocatalytic process are found to be OH. In addition, the m-TiO 2 -NTs exhibit excellent thermal and photocatalytic stability even after six recycles. This work demonstrates a novel way to fabricate mesoporous TiO 2 nanotubes that have multiple channel tubular structure and to apply them in environmental photocatalysis.