TAILORING THE ASSEMBLY OF GRAPHENE MATERIALS IN WATER-BASED WET SPINNING PROCESS

Abstract

Graphene is one of the most attractive carbon-based materials due to its extraordinary material properties originating from the atomically single- or small-number-layered structure. Integration of 2D graphene sheets into macroscopic architectures such as fibers illuminates the probability to transfer the excellent properties of individual graphene into advanced 3D ensembles for promising applications. However, the lack of effective, low-cost and convenient assembly strategy has blocked its further development. Therefore, water-soluble graphene oxide (GO), an oxidized form of graphene, is an alternative precursor for building 3D frameworks. Herein, we demonstrate that neat and macroscopic GO fibers can be easily fabricated through wet spinning technique. The self-assembled fibers further undergo intense thermal reduction and form neat graphene fibers. Surprisingly, the electrical and thermal conductivity of these graphene fibers is found to be much higher than polycrystalline graphite and other types of 3D carbon-based materials without sacrificing mechanical strength which can be applied to capacitors and energy storage devices. In addition, this one-step spinning technique can be applied to the transportation and storage of graphene oxide. GO is commonly synthesized in water by Hummers’ method and should be transported in water dispersion. Moreover, in the solution-based synthesis, GO suffers from severe restacking between individual sheets and thus loses its material identity and advantages. With the help of wet spinning, GO water suspension smartly extracts into dense fibers, which is much easier to handle compared to bulky water bottles and then bring down the transportation cost. We introduce sodium hydroxide as a coagulation agent to rapidly acquire GO fibers without restacking as well as altering its liquid crystallinity.