New hybrid titanate elongated nanostructures through organic dye molecules sensitization

This study reports on a novel chemical route to synthesize new elongated titanates nanostructured hybrid materials by the combination of titanate nanofibers (TNFs) with organic dye molecules. The influence of the sodium/proton replacement on the adsorption and intercalation characteristics of the TNFs materials was analysed. Depending on the sodium/proton content, materials with surface areas in the 21.08–38.90 m2/g range were obtained. Due to their molecule size and shape, and anticipating their intercalation between the TiO6 layers, the cationic molecules chosen for this study were thionine, methylene blue, crystal violet and rhodamine 6G. The sample with the highest sodium content was the best material on up taking dyes from aqueous media. The amount of the immobilized dyes was higher than the one predictable for the formation of a monolayer in an adsorption process. The intercalation of thionine, methylene blue and crystal violet between the TiO6 layers was accomplished. The characterisation results obtained by adsorption, XRD and FTIR are in agreement with the production of these new hybrid structures, with the organic molecules located within the TiO6 layers. The results also demonstrate that only the thionine was incorporated in the protonated titanate structure, due to the smaller distance between the layers. The optical characterisation of the prepared materials by DRS also indicates that intercalated and adsorbed dyes have strong influence on the optical properties of the new hybrid materials prepared.