Ultra-strong and conductive graphene fiber via sacrificial layer technology

•The alignment of GO molecules was controlled by microfluidic spinning.•Using the sacrificial layer technique, the outer SA layer could be removed.•A new method for the preparation of RGO fibers. Microfluidic spinning technology (MST) is an emerging method specialized in the construction of multi-component and multi-structure fibers. In this study, we designed an ultra-strong coaxial graphene oxide (GO) fiber by employing sodium alginate (SA) as sheath flow via MST. The diameter of the fiber and the arrangement of GO molecules could be controlled by adjusting process parameters. More importantly, the outer SA layer could be removed during a subsequent reduction process of GO, which served as a sacrificial layer to GO fiber formation and enhanced the fiber strength. Ultimately, this could achieve a conductive graphene fiber with a maximum strength of 365.2 MPa and electrical conductivity of 52 Ω/cm via a common wet spinning mechanism.