| Abstract
| - Trimodally sponge-like macro-/mesoporous titania was prepared by hydrothermal treatment of precipitatesof tetrabutyl titanate (Ti(OC4H9)4) in pure water. Effects of hydrothermal time on the phase composition,porosity, and photocatalytic activity of hierarchically porous titania were investigated by X-ray diffraction(XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolutiontransmission electron microscopy (HRTEM) and N2 adsorption−desorption measurements. All TiO2 powdersprepared at 180 °C showed trimodal pore-size distributions in the macro-/mesoporous region: fine intraparticlemesopores with peak pore diameters of ca. 3.7−6.9 nm, larger interparticle mesopores with peak pore diametersof ca. 23−39 nm, and macropore with pore diameter of ca. 0.5−3 μm. With increasing hydrothermal time,crystallinity, and average anatase crystallite size, pore size and pore volume increased, while specific surfacearea decreased. The hierarchically porous titania prepared at 180 °C for 24 h displayed an especially highphotocatalytic activity probably due to its special pore−wall structure, and its photocatalytic activity wasabout three times higher than that of Degussa P-25. This trimodally sponge-like macro-mesostructured titaniacould find its varieties of potential applications in photocatalysis, catalysis, solar cell, and separation andpurification processes. A new concept “biomemitic photocatalysis” has been proposed, which may providenew insight into preparation of advanced photocatalytic materials by mimicking surface structures of plantleaves.
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