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Graphical abstract Highlights • Mesoporous TiO 2 -SiO 2 nanocomposites with 3D tunable intrawall pores were prepared. • The preparation method is simple, moderate and facilely reproducible. • The photocatalysts with 3D large intrawall pores display quite excellent activities. • The activities are far higher than that of the parent material and P25 photocatalyst. • The photocatalysts with large intrawall mesopores are rather stable and reusable. Abstract Mesoporous anatase crystal-silica nanocomposites with three-dimensional (3D) uniform and tunable intrawall mesopores connecting the mesochannels have been successfully prepared using the approach of first synthesizing titania-silica nanocomposites with ordered two-dimensional hexagonal mesochannels via "synchronous-assembly" of inorganic precursors with surfactant, then "extracting silica". The uniform intrawall pores can be finely tuned in 3.6–5.6 nm by the strategy of adopting a large amount of silica in the walls, a very high crystallization temperature and mild silica extraction. The 3D interconnectivities of the mesochannels increase with extraction, but the mesostructures are retained intact. The average size of uniform anatase nanocrystals is 11.2 nm. This method is moderate, simple and facilely reproducible. The diffusion efficiencies of methylene blue (MB) in the mesostructures elevate with the intrawall mesopore size. The transient steady-state concentrations of •OH radicals rise fast with the intrawall pore size. The degradation rate of MB on the representative photocatalyst possessing large intrawall mesopores is extremely high (0.372 min−1), which is as high as 7.3 times that on the parent material, even up to 38.8 times that upon P25 photocatalyst. Our results clearly illustrate that the large intrawall mesopores play an overwhelming role in the increments of activities, while the matched adsorbability play an important synergetic role. Additionally, our photocatalysts are quite stable and reusable. Such results have not been seen in the literature till now. Furthermore, this approach is generally applicable to other metal-oxides-based materials, opening up a new avenue to rationally design and prepare mesostructures with 3D large intrawall mesopores, suitable adsorption and unexpected photocatalytic performances. [ABSTRACT FROM AUTHOR]

In this article, an ordered two-dimensional (2D) hexagonal mesoporous anatase crystals–silica nanocomposite was first synthesized using synchronous-assembly of surfactant and inorganic precursors molecules, and then a three-dimensional (3D) interconnected mesoporous anatase TiO 2 was prepared via an “ extracting silica ” approach. The results show that the mesopore channels in our titania are highly connected by plenty of 3D uniform intrawall mesopores while retaining mesostructural integrity and regularity. The TiO 2 prepared is completely anatase crystalline with uniform nanocrystals (13.0 nm in size) and a high specific surface area (∼ 145 m 2 /g). This method is mild, simple and can be easily repeatable. The photocatalytic degradation rates of Acid Red 1 (0.173 min −1 ) and microcystin−LR (2.57 min −1 ) on the interconnected mesoporous TiO 2 are very high, which are 41.6 and 2.85 times higher than that of the parent sample; 29.2 and 7.20 times that of P25 photocatalyst, respectively. These results clearly demonstrated that the 3D interconnected mesostructure played a key role in the activity increments. In addition, our photocatalysts are considerably stable and reusable. To the best of our knowledge, such results have not been seen in the literature before. Furthermore, the fundamentals of this study would provide new insights for the rational design and preparation of 3D highly interlinked mesoporous metal-oxides with unique photocatalytic performances. [ABSTRACT FROM AUTHOR]

• Mesoporous anatase titania with 3D large secondary mesopores was prepared. • The preparation approach is mild, simple and facilely reproducible. • The photocatalyst with 3D large secondary pores displays quite excellent activities. • The activities are far higher than that of P25 photocatalyst and the parent sample. • The photocatalyst with 3D large secondary mesopores is rather stable and reusable. A mesoporous titania (SN2) with three-dimensional (3D) large secondary mesopores (6.2 nm) highly connecting the mesochannels was prepared employing the method of first synthesizing an ordered 2D hexagonal mesoporous titania-silica nanocomposite (SN1) via "synchronous-assembly" of inorganic precursors with surfactant molecules, then "extracting silica". Our tactic adopts a large amount of silica, a high crystallization temperature and mild silica extraction. The 3D interconnectivities of the resultant mesochannels are quite high, but the mesostructures are retained intact. Titania is fully anatase crystalline with uniform nanocrystals size (11.2 nm) and a high specific surface area (∼ 174 m2 g−1). This strategy is gentle, simple and easily reproducible. SN2 presents extremely-high photocatalytic degradation activities to anionic azo dyes like acid red 1 and reactive brilliant red X3B, which reach 55.9 and 51.1 times that of commercial P25 photocatalyst, even up to 87.0 and 84.7 times that of SN1, respectively; and far higher than that of the contrast sample (CS) possessing 3D small secondary mesopores (2.7 nm). Additionally, SN2 also displays a very high activity to microcystin-LR, which is much higher than that of P25 and CS, respectively. Our results clearly indicate that the large secondary mesopores play a key role in the great increases of activities. Moreover, our photocatalyst is considerably stable and reusable. Such results have hitherto not been seen in the literature. Furthermore, this method would pave the way for the rational design and preparation of ordered mesoporous other metal-oxides with large secondary mesopores and unexpected performances. [ABSTRACT FROM AUTHOR]