A new ion exchange behavior of protonated titanate nanotubes after deprotonation and the study on their morphology and optical properties

► A novel ion exchange behavior of protonated titanate nanotubes after deprotonation. ► The exchangeability of protonated titanate nanotubes are not as inert as past reported. ► The tube walls of H2Ti3O7 nanotubes is observed to get loosened after ion exchange. ► The paper proves a new and easy way to modify protonated titanate nanotubes.