In-Situ Morphology Regulation of Electrospun Carbon Nanofiber Mats through Tuning the Thermal Stabilization Parameters

Most previously reported methods for creating interconnected carbon nanofiber (CNF) networks involve multiple complex steps and require precise control over various fabrication parameters. This study presents a straightforward and innovative approach to fabricate CNF architectures with tunable morphologies, ranging from isolated fibers to highly interconnected networks, porous and non-porous films by simply adjusting the heating rate during the stabilization of electrospun polyacrylonitrile (PAN). Leveraging the time-dependent thermochemical properties of PAN, the method eliminates the need for complex, multi-step processes. DSC analysis of PAN at varying heating rates led to this novel approach for controlling the morphology of electrospun CNF mats by balancing the rate of a physical phenomenon —melting— against a set of chemical reactions —stabilization—. By tuning the heating rate during the stabilization process at four levels of 0.25 °C/min, 0.5 °C/min, 1 °C/min and 2 °C/min, CNF mats with varying morphologies were obtained. Crystallographical methods represent a development in crystalline structure with an increase in in-plane crystalline size from 8.078 nm to 8.762 nm, an increase in number of stacking layers from 2.19 to 2.30 and a decrease in I D /I G from 2.380 to 2.195 when the morphology tends from separated fibers to interconnected networks. The resulting fully interconnected CNF mats exhibit a remarkable electrical conductivity of 62.81 S/cm, representing a significantly higher than 13.87 S/cm for isolated fibers, while maintaining similar chemical and structural properties across different morphologies. This work offers a controllable and efficient route to engineer CNF-based materials, highlighting their significant potential for advanced electrochemical applications.