Fig. 2. Microstructure characterization of the radially oriented mesoporous TiO₂ microspheres.

(A) In situ synchrotron radiation 1D SAXS patterns of the mesoporous TiO₂ microsphere products harvested at different intervals of reaction time. Insets: Corresponding schematic representation of the four samples. a.u., arbitrary units. (B to E) 2D SAXS images of the four samples. (F) SEM image of the mesoporous TiO₂ microspheres. Inset: SEM image of a single mesoporous TiO₂ microsphere. (G) SEM image of a single ultramicrotomed, radially-oriented mesoporous TiO₂ microsphere with a large number of interchannel pores (~5 to 15 nm in diameter, marked by red circles). Inset: Corresponding schematic representation of the structure models for the radially oriented channels with interchannel pores. (H and I) TEM images of a single ultramicrotomed, mesoporous TiO₂ microsphere.