Abstract
Titania (TiO2) nanofibers were fabricated by
electrospinning three representative spin dopes made of
titanium (IV) n-butoxide (TNBT) and polyvinylpyrrolidone
(PVP) with the TNBT/PVP mass ratio being 1/2 in three
solvent systems including N,N-dimethylformamide (DMF),
isopropanol, and DMF/isopropanol (1/1 mass ratio) mixture,
followed by pyrolysis at 500 C. The detailed
morphological and structural properties of both the
as-electrospun precursor nanofibers and the resulting final
TiO2 nanofibers were characterized by SEM, TEM, and
XRD. The results indicated that the precursor nanofibers
and the final TiO2 nanofibers made from the spin dopes
containing DMF alone or DMF/isopropanol mixture as the
solvent had the common cylindrical morphology with
diameters ranging from tens to hundreds of nanometers,
while those made from the spin dope containing isopropanol
alone as the solvent had an abnormal concave
morphology with sizes/widths ranging from sub-microns to
microns. Despite the morphological discrepancies, all
precursor nanofibers were structurally amorphous without
distinguishable phase separation, while all final TiO2
nanofibers consisted of anatase-phased TiO2 single-crystalline
grains with sizes of approximately 10 nm. The
electrospun TiO2 nanofiber mat is expected to significantly
outperform other forms (such as powder and film) of TiO2
for the solar cell (particularly dye-sensitized solar cell) and
photo-catalysis applications.