Preparation mechanism of hierarchical layered structure of graphene/copper composite with ultrahigh tensile strength

Abstract

Nacre-like composite is promising to realize the intriguing properties of graphene in metal matrix. However, how to fabricate the composite with nacre-like structure and improve effectively its property is still challenging. Here we report a facile synthesis of reduced graphene oxide(RGO)/copper(Cu) composite with hierarchical layered structure based on molecular level mixing and self-assembly. The effects of pH value, temperature, mixing method and graphene content on the microstructure and mechanical property of composite were investigated. The pH value and temperature are the main factors in the formation of hierarchical layered structure. For macroscale microstructure, the composites consist of parallel carbon-rich strip aggregates and carbon-poor matrix. For microscale microstructure, the carbon-rich aggregate contains many micro-layered grains composing of alternating layers of graphene and copper, forming a nacre-like composite structure. Furthermore, it is believed that the length-width ratio of macroscopic aggregates related with the mixing method has a significant impact on the mechanical properties of composites. The tensile strength of the 2.5 vol% RGO/Cu composite is as high as 748 MPa. Moreover, good electrical conductivity is also obtained in the composites. This work provides a better understanding of design graphene based composites with hierarchical layered structure and high performance.