New Mechanistic Insight of Low Temperature Crystallization of Anodic TiO2 Nanotube Array in Water

A facile low-temperature crystallization method was recently developed for the synthesis of anodic TiO 2 nanotubes (NTs). This novel method requires less energy and less sophisticated equipment than traditional high-temperature sintering, but the underlying mechanisms have not yet been elucidated. Here, we systematically studied the low-temperature crystallization mechanism of anodic TiO 2 NTs by using different solvents and treatment time. For the first time, we notice a dramatic change of the surrounding water and discuss the TiO 2 nanocrystals (NCs) byproducts of the low-temperature crystallization process. Accordingly, we propose a dissolution–recrystallization mechanism in which dissolved Ti(OH) 6 2– dehydrates and crystallizes in situ to form anatase NTs as well as anatase NCs. Overall, this work provides a mechanistic insight into this low-temperature crystallization method, which could benefit the optimization and scale-up of industrial TiO 2 NT production.