One-dimensional carbon–SnO2 and SnO2 nanostructuresvia single-spinneret electrospinning: tunable morphology and the underlying mechanism

Abstract

Carbon–SnO₂ hybrid nanofibers with tunable morphology were prepared from polyacrylonitrile (PAN) and tin compounds via single-spinneret electrospinning and subsequent carbonization. Different tin compounds, including tin acetate (Sn(CH₃COO)₂), tin chloride dihydrate (SnCl₂·2H₂O), tin sulfate (SnSO₄) and tin sulfide (SnS), were chosen as precursors of SnO₂ to tune the morphology of carbon–SnO₂ nanofibers. Morphology of the obtained nanofibers was studied using a field emission scanning electron microscope (FESEM) and a transmission electron microscope (TEM), and their structures were characterized by thermal gravimetric analysis (TGA) and X-ray diffraction (XRD). A carbon–SnO₂ core–shell morphology is formed during carbonization when Sn(CH₃COO)₂ and SnCl₂·2H₂O are used as precursors of SnO₂, while uniform distribution of Sn compounds in a carbon matrix is observed with SnSO₄ or SnS as the precursor. Our study demonstrates that the Kirkendall effect, which is responsible for the formation of the core–shell morphology during carbonization, is strongly dependent on melting points and decomposition behaviours of the precursors. SnO₂ nanofibers and nanotubes with a high aspect ratio were produced upon burning out carbon, and their morphology is dependent on that of the corresponding hybrid nanofibers. TEM studies show that the SnO₂ nanofibers/nanotubes are constituted of SnO₂ single crystals, yet the grain size and facet varies with the precursor. The Brunauer–Emmett–Teller (BET) study verifies that the nanofibers/nanotubes have a large surface area, which also varies with the precursors used.