Figure 1 (A) Schematic illustration of the setup for electrospinning nanofibers having a core/sheath structure. The spinneret was fabricated from two coaxial capillaries, through which heavy mineral oil and an ethanol solution containing PVP and Ti(OiPr)₄ were simultaneously ejected to form a continuous, coaxial jet. (B) TEM image of two as-spun hollow fibers after the oily cores had been extracted with octane. The walls of these tubes were made of a composite containing amorphous TiO₂ and PVP. (C) TEM image of TiO₂ (anatase) hollow fibers that were obtained by calcining the composite nanotubes in air at 500 C. (D) SEM image of a uniaxially aligned array of anatase hollow fibers that were collected across the gap between a pair of electrodes. These fibers were fractured using a razor blade to expose their cross-sections. In the preparation of all these samples, the feeding rate for heavy mineral oil was 0.1 mL/h and the concentrations of Ti(OiPr)₄ and PVP were 0.3 and 0.03 g/mL, respectively. The voltage of electrospinning was 12 kV.

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