Transformation of layered titanate nanosheets into nanostructured porous titanium dioxide in polycation solution

Nanostructured porous TiO2 particles constructed from nanorod-like crystals were prepared from a layered titanate nanosheet precursor. The synthesis process includes two steps: construction of a porous nanostructure by assembling the nanosheets with poly (diallyldimethylammonium) (PDDA) polycations, and topotactic transformation of the nanostructured titanate nanosheets into anatase-type TiO2 nanocrystals by hydrothermal reaction. The reaction process and nanostructured porous particles were characterized by XRD, DTA-TG, SEM, TEM analyses, and measurements of specific surface area, pore size distribution, ruthenium dye (N719) adsorption, and photocatalytic activity. The morphology of the porous particles is dependent on the PDDA concentration in the reaction system. Spherical particles constructed from nanorod-like anatase crystals can be prepared under the high PDDA concentration conditions. The topotactic transformation reaction from the titanate nanosheet to anatase resulted in the formation of anatase nanocrystals which preferentially expose the (0 10) plane of anatase on the surface. The surface of the nanostructured porous anatase particles shows high N719 dye adsorption ability and high photocatalytic activity, which have potential application in dye-sensitized solar cells. (C) 2008 Elsevier Inc. All rights reserved.