Microstructure of polyacrylonitrile-based activated carbon fibers preparedfrom solvent-free coagulation process

Abstract

Polyacrylonitrile precursor fibers prepared using a solvent-free coagulation process were stabilized, carbonized, and physically activated bycarbon dioxide into activated carbon fibers (ACFs). The activation temperature varied from 600 to 900?C while the activation time was 1 h. Atomicforce microscopy was used to observe the surface morphology, as well as the surface roughness of the ACFs. Higher pyrolysis temperature formedrougher surfaces, and increased the pore sizes. Meanwhile, Fourier transform infrared spectroscopy revealed more conversion of oxygen containingfunctional groups to carbonaceous materials as the activation temperature increased. Moreover, the microstructure properties were thoroughlycharacterized by the X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) studies. XRD analysis showed that the activationof the ACFs shrank the ordered structure, reducing the D-spacing from 0.358 to 0.347 nm for the fibers prepared at activation temperatures of600 to 900?C. Meanwhile, XPS analysis concluded that that the oxygen containing functional groups were still retained even at high activationtemperatures while the nitrogen containing functional groups were reduced during the high temperature activation in the CO² atmosphere.