Nanofibrous TiO produced using alternating field electrospinning of titanium alkoxide precursors: crystallization and phase development.

High-yield, free-surface alternating field electrospinning (AFES) was effectively used in the fabrication of titanium oxide nanofibrous materials from the precursors based on titanium alkoxide and a blend of polyvinylpyrrolidone and hydroxypropyl cellulose. The alkoxide/polymer mass ratio in the precursor solution has significant effects on the precursor fiber production rate as well as the structure of resulting TiO nanofibers after thermal processing of precursor fibers at temperatures from 500 to 1000 °C. Within the range of tested process parameters, the best fiber production rate of ∼5.2 g h was achieved, in terms of the mass of crystallized TiO nanofibers, with the precursor that corresponded to 1.5 : 1 TiO/polymer mass ratio. TiO nanofibers produced by calcination at 500 °C for 3 h had 100-500 nm diameters and were composed of anatase (20-25 nm crystallite size) with rutile content 0.1-6.0 mol%, depending on the precursor composition. A considerable amount of anatase phase (up to 80 mol%) can be retained after thermal processing of TiO nanofibers at 750 °C for 3 h. A nanofibrous material composed of smooth and long, predominantly monocrystalline rutile, fibrous segments was produced at 1000 °C from the precursor with 2.5 : 1 TiO/polymer mass ratio.