Tubular titania nanostructures via layer-by-layer self-assembly

Nanostructured titania-polyelectrolyte composite and pure anatase and rutile titania tubes were successfully prepared by layer-by-layer (LbL) deposition of a water-soluble titania precursor, titanium(IV) bis(ammonium lactato) dihydroxide (TALH) and the oppositely charged poly(ethylenimine) (PEI) to form multilayer films. The tube structure was produced by depositing inside the cylindrical pores of a polycarbonate (PC) membrane template, followed by calcination at various temperatures. The morphology, structure and crystal phase of the titania tubes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorbance measurements. The as-prepared anatase titania tubes exhibit very promising photocatalytic properties, demonstrated by the degradation of the azodye methyl orange (MO) as a model molecule. They are also easily separated from the reaction system by simple filtration or centrifugation, allowing for straightforward recycling. The reported strategy provides a simple and versatile technique to fabricate titania based tubular nanostructures, which could easily be extended to prepare tubular structures of other materials and may find application in catalysis, chemical sensing, and nanodevices