The Effect of Hydrothermal Conditions on the Mesoporous Structure of TiO2 Nanotubes
Journal of Materials Chemistry (up to 2012)
, E-ISSN: 1364-5501
Bavykin Dmitry V.
Parmon Valentin N.
Lapkin Alexei A.
Novosibirsk State University
The University of Bath
University of Southampton
A systematic analysis of the influence of preparation conditions in the alkali hydrothermal synthesis on the
morphology of TiO2 nanotubes is performed using HRTEM and low temperature nitrogen adsorption. The
possible mechanisms of nanotube formation are reviewed and a mechanism based on the key stage of wrapping
of intermediate multilayered titanate nanosheets is suggested. The driving force for wrapping is considered to
be the mechanical stress arising during crystallisation/dissolution. The average diameter of the nanotubes was
found to depend on the temperature and on the ratio of weight of TiO2 to the volume of sodium hydroxide
solution. An increase in the temperature from 120 to 150 uC results in an increase in the average nanotube
diameter. Subsequent increases in the temperature result in the formation of non-hollow TiO2 nanofibers with
an average diameter of 75 nm, a wide distribution in diameter and a length in excess of 10 mm. The increase of
the TiO2 : NaOH molar ratio results in an increase in the average diameter of nanotubes and a decrease of
surface area. The average inner diameter of TiO2 nanotubes varied between 2 and 10 nm. The pore-size
distribution was evaluated from TEM, and low-temperature nitrogen adsorption data using the BJH method. It
was shown that nitrogen adsorption is a suitable method for characterisation of the pore morphology of