Optimized thermal oxidation strategy for amorphous carbon removal in wet-spun carbon nanotube fibers

Abstract Carbon nanotubes (CNTs) represent an advanced material with exceptional mechanical, electrical, and thermal properties. However, realizing these properties in fiber applications requires effective removal of impurities particularly amorphous carbon. This study presents an optimized thermal oxidation strategy to remove amorphous carbon while preserving the nanotube structure. We investigated various oxidation conditions, focusing on temperature-time conditions and their effects on single-walled CNT (SWCNT) structure and fiber formation. Here, we suggested the optimal oxidation parameters (400 °C, 12 h) that effectively removed amorphous carbon while maintaining the sp 2 carbon structure. SWCNTs treated under optimal conditions exhibited improved dispersibility in chlorosulfonic acid and formed a liquid-crystalline phase. The resulting SWCNT fibers exhibited improved specific tenstile strength (0.80 N tex −1 ) and modulus (124 N tex −1 ) compared to fibers treated at high temperatures (500 °C) where structural degradation occurred due to excessive thermal oxidation. This study provides a foundational approach to fabricating high-performance SWCNT fibers through a controlled oxidation process, contributing to the development of high-performance CNT fibers for various applications.