Topological properties of titanate nanotubes

We report a simple ultrasonic-assisted ion-exchange/intercalation process that enables unwrapping one-dimensional (1D) titanate nanotubes into two-dimensional (2D) titanate nanosheets. The existence of this 1D to 2D topotactic transformation reveals that the titanate nanotubes could be considered as quasi-2D crystallites with excellent 2D properties such as exfoliation/delamination reactivities although they have the 1D morphology. The resulting titanate nanosheets possess larger band gap energy (similar to 3.75 eV) than that of the original nanotubes (similar to 3.30 eV), which might be attributed to the quantum size effect within the 2D titanate nanosheets with small thickness.