ABSTRACT
The oxygen vacancy concentration increases with increase in calcination temperature in these atmospheres, whereas it remains constant in air. This chapter uses a novel strategy to create oxygen vacancies in a mixture of amorphous titania, crystalline anatase, and crystalline rutile in electrospun titania nanofibers to narrow the band gap. Amorphous titania nanofibers are synthesized by electrospinning, and their morphology and band gap are characterized before and after calcination in air–argon mixtures, using field emission scanning electron microscopy, energy dispersive spectroscopy, and UV–visible spectrometry. The measured gap of 2.18 eV for heating in 100% argon is related to the titania phase composition (10% anatase and 63% rutile) for which the concentration-weighted gap would be 3.05 eV, which is approximately 0.87 eV greater than the measured gap of 2.18 eV. The 0.87 eV difference is attributed to the oxygen vacancy development.
