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

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 Lc(002) and La(10) values were calculated to be 1.85–2.15 and 2.23–3.36 nm, respectively. The Lc(002) and La(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.