Tough, Strong, and Conductive Graphene Fibers by Optimizing Surface Chemistry of Graphene Oxide Precursor

Abstract Graphene fibers with integrated mechanical and multifunctional properties are highly required for various potential applications. However, it remains a challenge to efficiently produce high‐performance graphene fibers because of the imperfect structures and harsh graphitization conditions. Herein, a scalable additive‐free wet‐spinning methodology is demonstrated for producing strong, tough, and conductive pristine graphene fibers by optimizing the surface chemistry of graphene oxide (GO) sheets and controlling their spinning and assembly behavior. Benefiting from GO with fewer surface terminations and low structural defects ( f ‐GO), the pristine f ‐GO fibers possess a compact and ordered microstructure and strong interlayer interactions, giving a record high tensile strength of 791.7 MPa and high toughness of 24.0 MJ m −3 due to the stretching‐induced toughening behavior. After the mild chemical reduction, reduced f ‐GO fibers inherit the optimized microstructure and present an outstanding tensile strength of 875.9 MPa and high toughness of 13.3 MJ m −3 . Furthermore, the repairable structural defects on the f ‐GO sheets allow the instant restoration of intrinsic conjugated structures, affording a superb electrical conductivity of 1.06 × 10 5 S m −1 . Therefore, this study provides a facile, efficient, and scalable methodology for the fabrication of high‐performance and multifunctional graphene fibers and flexible wearable devices.