Effect of mechanical stirring and temperature on dynamic hydrothermal synthesis of titanate nanotubes

In the late century, it has been clearly demonstrated that titanate nanotubes (TNTs) are attractive nanomaterials with various potential applications due to their interesting properties. In this work, an essential reaction parameter, rarely considered in the literature, has been studied: stirring during hydrothermal synthesis. For this purpose, an intermittent mechanical stirring, ranging from 0 to 20 min/h, has been applied during the TNTs synthesis using a new dynamic hydrothermal reactor. It was proved that a long stirring cycle (more than 10 min/h) at 150 °C and an overall reaction time of 16 h promotes nanoribbons synthesis instead of nanotubes. In this context, a detailed morphological and chemical study has been carried out. The effect of temperature in the acceleration of the precursor dissolution was also studied. The present study shows for the first time that rapid reaction kinetics was reached at high temperature and using continuous stirring and induced the formation of multiwall TNTs with up to 10 walls after only 30 min of hydrothermal treatment. Many characterization techniques were used to study the structural, morphological and optical properties of each output product. - Highlights: • A dynamic hydrothermal synthesis of titanate nanotubes (TNTs) is proposed. • Long vigorous mechanical stirring promotes nanoribbons morphology. • Temperature and continuous stirring accelerate TiO₂ dissolution and TNTs synthesis. • Continuous stirring promotes multiwall TNTs formation for a short reaction time.