Defects induced the bilayer graphene-copper hybrid and its effect on mechanical properties of graphene reinforced copper matrix composites

Graphene/Cu composites have shown great potential in the fields of mechanical engineering, electronic devices and so on. In this study, the impacts of vacancies on the interlayer interaction of bilayer graphene (BLG) and the resultant influence of graphene interlayer bonding on the interfacial bonding, tensile strength, and slipping mechanism of the graphene/Cu composites are comprehensively investigated based on first-principles calculations. It was revealed that clustering of cross-layer vacancies (CV) can initiate the formation of distinct hybrid types (sp2 hybrid, sp3 hybrid) of interlayer bonds, resulting in enhanced interlayer bonding of BLG. Unlike the van der Waals interaction between graphene and Cu, vacancies cause the Cu atoms on the surfaces to be embedded in the BLG, forming the graphene-copper hybrid that can improve the combination of Cu and graphene. The notable hybridization between the 2p orbitals of the unsaturated C atoms neighboring the vacancies and the 4s, 3d orbitals of the Cu atoms on the surfaces drives this effect. BLG with interlayer bonds can substantially improve the interfacial bonding and mechanical properties of the composites. This research provides a novel outlook for the interface engineering research and innovative development of graphene/Cu composites by regulating the interlayer bonding of grapheme.