High-yield preparation of titanium dioxide nanostructures by hydrothermal conditions.

The effect of the neutral surfactant dodecylamine and octadecylamine on the synthesis of TiO2-based nanostructures by the treatment of anatase with NaOH under hydrothermal conditions in the temperature range 120-150 degrees C and different reaction times was investigated. The products analyzed by electron microscopy, X-ray diffraction, FT-IR and elemental analysis contains--depending of the amine, the temperature and the duration of the hydrothermal treatment--spherical and tubular species containing the acid H2Ti3O7. The formation of morphologically almost pure phases constituted by nanospheres and nanotubes were obtained at 130 degrees C after about 30 and 50 h respectively. Using dodecylamine, structurally fragile tubular amine containing nanocomposites are obtained, while in the case of the octadecylamine, notoriously stable purely inorganic nanotubes are formed. The role of the amine in these reactions is discussed.