Fabrication of carbon‐core/TiO₂‐sheath nanofibers from poly (vinyl alcohol)/TiO₂ nanofibers by iodine‐vapor treatment and carbonization: effect of carbonization temperature

Abstract

ABSTRACT Carbon‐core/TiO 2 ‐sheath nanofibers have been fabricated by iodine‐vapor treatment and carbonization of poly (vinyl alcohol) (PVA)/TiO 2 composite nanofibers that were prepared by sol‐gel coating of TiO 2 on the electrospun PVA nanofibers. The carbon/TiO 2 nanofibers had diameters of a few hundred nanometers and sheaths of tens of nanometers. The effects of carbonization temperature on the structures and the electrical conductivity of nanofibers were investigated in the temperature range from 773 to 1073 K. The crystal structure of TiO 2 sheath was anatase at low carbonization temperatures. The sample carbonized at 1073 K contained a small portion of rutile phase coexisting with anatase. The formation of carbon core with low degree of graphitization was confirmed for the sample carbonized over 873 K. The electrical conductivity was drastically improved by 6 orders of magnitude by increasing the carbonization temperature from 773 to 1073 K. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.