Abstract
Submicron scale vanadia/silica hybrid nanofiber mats have been produced by electrospinning silica sol‐gel precursor containing vanadium oxytriisopropoxide (VOTIP), followed by calcinations at high temperature. The properties of the resulting inorganic hybrid nanofiber mats are compared to those of electrospun pure silica nanofibers. SEM images show fibers are submicron in diameter and their morphology is maintained after calcination. Physisorption experiments reveal that silica nanofiber mats have a high specific surface area of 63 m2/g. FT‐IR spectra exhibit Si—O vibrations and indicate the presence of V2O5 in the fibers. XPS studies reveal that the ratio of Si to O is close to 0.5 on the surface of fibers and the amount of vanadium on the surface of fibers increases with calcination. XRD diffraction patterns show that silica nanofibers are amorphous and orthorhombic V2O5 crystals have formed after calcination. EFTEM images demonstrate the growth of crystals on the surface of fibers containing vanadium after calcination. SEM images of fibers with high‐vanadium content (50 mol% V: Si) show that vanadia crystals are mostly aligned along the fiber axis. XPS shows an increase in vanadium contents at the surface, and XRD patterns exhibit an increase in the degree of crystallinity. A coaxial electrospinning scheme has successfully been employed to selectively place V2O5 in the skin layer.
Highlights
Electrospinning is a fiber formation process typically used to produce nonwoven polymer fiber mats with diameters one or two orders of magnitude smaller than conventional textile fibers
When vanadia/silica fibers were desired, a vanadium oxytriisopropoxide (VOTIP)/EtOH solution containing half of the overall EtOH contents was added after vigorous mixing of the Tetra(ethyl) ortho silicate (TEOS)/EtOH and H2O/HCl solutions
Silica nanofiber mats have been produced by combining solgel synthesis and electrospinning without using any polymer binder
Summary
Electrospinning is a fiber formation process typically used to produce nonwoven polymer fiber mats with diameters one or two orders of magnitude smaller than conventional textile fibers. Electrospinning produces mats with large surface area to mass ratios, typical surface areas can be 10 m2/g for fiber diameters of 500 nm and 1000 m2/g for diameters around 50 nm [1]. During electrospinning a strong electric field is used to draw a solution from the tip of a capillary to the collector. The electrostatic field causes a pendant droplet of the solution at the capillary tip to deform into a conical shape or a Taylor cone. The solvent begins to evaporate immediately after the jet is formed causing the deposit of a thin fiber on the collector plate [1]. We refer the reader to recent reviews that elaborate on the versatility and promise of electrospinning processes [1,2,3]
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