A study on the effect of starting material phase on the production of trititanate nanotubes

Mixed phase TiO₂ powders of different composition and particle size were subjected to the hydrothermal reaction with 10 M NaOH. It was found that the anatase phase component of the starting material is easily converted to trititanate nanotubes at 140 °C. At this temperature the rutile phase remains unreacted, however at 170 °C it reacts to form trititanate plates and belts. When the reaction time is increased to 7 days, all the TiO₂ is converted to trititanate and the morphology is exclusively nanoplates and belts, with the tube phase destroyed. Many researchers have observed some heterogeneity in their reaction products, but have mainly focussed on the nanotubes. We observed that the tubes are only prepared from the anatase phase component of a TiO₂ precursor, whereas the rutile component produces trititanate plates and sheets, irrespective of the reaction length. The particle size affects the rate of reaction, resulting in the phase transition being more easily visible in the reactions starting with the larger TiO₂ particle size.