Detailed investigation on titanium (IV) oxide nanofiber synthesized by combined sol-gel and electrospinning technique

Abstract

Titania nanofibers were prepared from sol-gel method combining with the electrospinning technique. Titanium (IV) isoproproxide (TTIP), polyvinyl pyrrolidone (PVP) and ethanol were mixed together and electrospun into titania/PVP composite nanofibers under the potential of 16 kV. Calcination of the composite nanofibers at 500oC resulted in the removal of polymer from the fibers, as well as the phase transformation of titania from amorphous to mixed phase of anatase and rutile. Changing the electrospinning collector plate from a flat collector to a rotating collector led to the fabrication of the axially aligned titania nanofibers with average diameter of 220 nm for the as-spun fibers and 120 nm for the calcined fibers. Effects of aging conditions and acetic addition on morphology and phase transformation of titania nanofibers after calcination were also investigated. The aging of the as-spun titania nanofibers under high level of humidity results in the reduction of rutile in the fibers after calcination at 500oC. Nevertheless, the morphology of titania nanofibers is changed at high level of humidity. Thickness of fiber layer is also one of the parameters affecting the effectiveness of the aging process. The addition of acetic acid into the electrospinning solution enhanced the stability of the alkoxide solution. It was also found that the addition of acetic acid significantly lower the crystallization temperature of titania. The average crystallite size of the calcined fibers tends to decrease with the presence of acetic acid in the system. Moreover, the addition the acetic acid into the system causes the reduction in size distribution of the as-spun fibers.