Raman spectroscopic evaluation of polyacrylonitrile‐based carbon nanofibers prepared by electrospinning

Abstract

Abstract Poly(acrylonitrile) (PAN) solutions in N , N ‐dimethylformamide were electrospun into webs consisting of 350 nm ultra‐fine fibers. The webs were oxidatively stabilized and followed by heat treatment in the range of 700–1000°C. Characterization of the microstructure of PAN‐based carbon nanofibers was performed by x‐ray diffraction, field‐emission scanning electron microscopy, electrical conductivity and Raman spectroscopy. The L c (002) and L a (10) values were calculated to be 1.85–2.15 and 2.23–3.36 nm, respectively. The L c (002) and L a (10) values increased by about 86% and 66%, respectively, when the heat treatment temperature (HTT) was increased from 700 to 1000°C. The electrical conductivity of carbonized PAN nanofiber webs increased with increasing carbonization temperature, being 6.8 × 10 −3 and 1.96 S cm −1 at 700 and 1000°C, respectively. The D and G bands from Raman scattering were fitted into a Gaussian–Lorentzian hybridized function, and the crystallite sizes in the nanofibers were evaluated from the R ‐values determined from the ratios of the intensity of the G band to that of the D band. The domain size of the graphitic layers was in the range 1.6–3.2 nm with higher values at higher HTT. Copyright © 2004 John Wiley & Sons, Ltd.