Structural characterization and morphology of electrospun TiO₂ nanofibers

This paper reports on structural characterization and morphology of titanium dioxide (TiO₂) nanofibers prepared by electrospinning using a solution that contained poly(vinyl pyrrolidone) (PVP) and titanium(diisoproproxide) bis(2,4-pentanedionate) 75 wt.% in 2-propanol. TiO₂ nanofibers with diameters of 80-100 nm were successfully obtained from calcination of the as-spun TiO₂/PVP composite nanofibers at above 300 °C in air for 3 h. The as-spun and calcined TiO₂/PVP composite nanofibers were characterized by TG-DTA, Raman spectroscopy, XRD, SEM, AFM, and TEM. The results indicated a significant effect of calcination temperature on the crystalline phase in the form of either anatase or mixed anatase-rutile and the morphology of the nanofibers. The anatase-to-rutile transformation and the grain growth during the calcination of the electrospun TiO₂/PVP composite nanofibers, as revealed by TEM, occurred simultaneously and affected each other. The rutile content was the highest (∼80%) at 800 °C, and it can be expected that the complete anatase-to-rutile transformation in the TiO₂ nanofibers would be above 800 °C.