2.2.2. Co-electrospinning process
Methods for synthesis of core/sheath TiO2/SiO2 nanofibers
were as follows: the prepared core and sheath solutions were
respectively transferred into the two syringes connected to the
inner and outer needles of the coaxial spinneret. The schematic
setup of the co-electrospinning route used in this work was
similar to our previous work [15]. A high-voltage of 12 kV was
supplied between the nozzle and collector. And the tip-to-
collector distance was set to 12 cm. Herein, we directly prepared
coaxial nanofibers with different sheath thickness by controlling
the feeding rate of the sheath solution which was fed at a rate of
0.5, 0.4, 0.3 mL/h for the samples S1, S2, S3, respectively, while the
core solution was fed at a fixed feeding rate of 0.4 mL/h. And the
feeding rates were controlled by a programmable syringe pump
(KDS-200, USA). The as-spun fibers were collected on a aluminum
foil collector. The as-spun nanofibers were subsequently calcined
to remove the remained solvents and decompose organic
materials at 500 8C for 3 h with a heating rate of 1 8C/min in a
muffle furnace. For comparison,