Structural and vibrational studies of tunnel-like titanate nanoribbons with good ion exchange capacity

Potassium titanate nanoribbons were synthesized by hydrothermal method treating TiO2 anatase in KOH aqueous solution. Titanates with different contents of remnant potassium were produced by treating the precursor sample with HCl. After acid treatment, a solution of NaOH was used to wash the sample with less potassium in order to promote the H-Na exchange. The morphology of the nanoribbons has been confirmed by transmission electron microscopy and the ion exchange by atomic absorption spectroscopy. X-ray diffraction, infrared and Raman spectroscopies showed that the samples are octatitanates with the ion content depending on the acid/basic washing process. XRD patterns revealed a decrease in the interlayer distance during the K-H exchange, indicating that the hydrogen ions are located in interlayer space. This distance has an intermediate value in the sample with sodium. FT-IR and Raman measurements showed that the less energetic modes are more affected by interlayer ions, implying that displacements of interlayer ions are involved, while the more energetic ones are related to vibrations mainly involving the TiO6 octahedra.