The dual role of electrospinning temperature in the synthesis of high-quality carbon nanofibers from a PAN/DMSO system

Abstract This study systematically investigates the non-monotonic influence of the electrospinning temperature (TE) on the properties of high-quality carbon nanofibers (CNFs) derived from a polyacrylonitrile (PAN)/dimethyl sulfoxide (DMSO) system. This work addresses a gap in understanding how initial processing conditions with a high-boiling-point green solvent (DMSO) dictate final CNF structure. PAN precursor fibers were fabricated via electrospinning at TE of 90, 95, 100, and 105 °C, followed by standard two-step thermal treatment (stabilization at 250 °C, carbonization at 1100 °C). A comprehensive analysis was performed using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Raman spectroscopy, and X-ray Photoelectron Spectroscopy (XPS). These studies identified a critical processing window at 100°C that yielded superior CNFs. These optimal CNFs were uniform and fracture-free (mean diameter: 302 nm), exhibiting an optimal balance of properties, including a highly ordered graphitic structure (Lc = 1.22 nm) and a low defect ratio (I D /I G = 0.92), representing the best compromise between structural order and morphological integrity. In contrast, lower TE (90 °C) caused fiber fracture during carbonization due to the presence of trapped residual DMSO. In contrast, higher TE (105 °C) promoted premature solvent evaporation and ‘skinning,’ resulting in significant structural defects (I D /I G = 1.20). A novel finding from XPS analysis confirms that TE≥100 °C initiates surface oxidation on the precursor fibers. These findings establish a clear, scalable protocol and demonstrate the key role of electrospinning temperature in modulating solvent evaporation dynamics and influencing early-stage chemical transformations. This control is crucial when using high-boiling-point solvents such as DMSO, enabling the rational design of CNFs for tailored applications (e.g., structural versus high-surface-reactivity materials).