Kinetics of Alkali Metal Ion Exchange into Nanotubular and Nanofibrous Titanates

The kinetics of intercalation of Li +, Na +, K +, and Cs + cations between the layers of titanate nanotubes and nanofibers have been studied in an aqueous suspension of nanotubes at 25 °C. The rate of intercalation was found to be similar for different cations and depended on the length of the nanotubes. The decrease in nanotube length resulted in a higher rate of ion exchange, indicating that the transport of cations in titanate nanotubes occurred probably along their length. In contrast, the transport of cations in titanate nanofibers probably dominated in the direction perpendicular to length. Correlations between the rate of intercalation and the crystal structure modification following intercalation have been established for nanotubular and nanofibrous titanates.