Exfoliation and reassembling route to mesoporous titania nanohybrids

To fabricate mesoporous photocatalysts with delaminated structure, the exfoliated layered titanate in aqueous solution was reassembled in the presence of anatase TiO₂ nanosol particles to induce a great number of mesopores and eventually a large surface area of TiO₂ photocatalysts. No (0/0) peaks corresponding to the layered titanate appear in the X-ray diffraction patterns of the reassembled hybrids, which suggests that the titanate nanosheets were randomly hybridized with TiO₂ nanoparticles without any restacking into the layered phase. According to the high-resolution transmission electron microscopy images of these nanohybrids, the randomly oriented titanate nanosheets can be seen clearly along with TiO₂ nanosol particles with spherical images, indicating that the exfoliated sheets are indeed incorporated with anatase nanosol particles to form porous materials. From N₂ adsorption-desorption isotherms, these nanohybrids are fairly high in specific surface area and in mesoporosity for effective photocatalysis (S_BET = ∼190 m²/g, pore size = ∼6 nm). The photocatalytic activity of the present mesoporous nanohybrids is superior to that of TiO₂ nanosol particles or layered titanate alone in terms of the degradation of organic pollutants such as 4-chlorophenol, methyl orange, and methylene blue.