Thermally Controlled Crystallization of Electrospun TiO₂ Nanofibers

Abstract

The anatase phase of TiO2 has been of great interest due to its photocatalytic activity. For enhanced photocatalytic activity, the polymorphic structure of anatase phase and the rutile phase was pursued to form the semiconductor-semiconductor junction, which could even further enhance photocatalytic activity. TiO2 nanofibers with large specific surface area were fabricated via electrospinning from ethanol-based sol while the phase development was controlled by heat treatment. TiO2 fibers were characterized by x-ray diffraction (XRD) and transmission electron microscopy (TEM) for the crystalline phase and its microstructure, respectively. Among different heat treatment temperatures tested, 700°C was found to have the smallest grains while having both semiconductor, i.e. rutile and anatase available. TiO2 calcined at 800°C also achieved the polymorphic structure of anatase and rutile phases, however showed significant grain growth.