Covalently Bonded Graphene Sheets on Carbon Nanotubes: Direct Growth and Outstanding Properties

Integrating 1D carbon nanotubes (CNTs) and 2D graphene with covalent bonds can inherit the outstanding properties of both components and obtain additional advantages. Here, this work reports the preparation of covalently bonded graphene/CNT (G/CNT) structure by a normal chemical vapor deposition method. Specifically, the pre-synthesized defects on the sidewall of CNTs act as nucleation sites for the growth of graphene sheets to form a branch-leaf structure. Graphene leaves restrict the sliding and re-stacking of CNTs, endowing G/CNT hybrid demonstrates excellent anti-agglomeration properties that are not present in either graphene or CNTs. In addition, the covalently bonded structure and high graphitization degree of graphene sheets and CNTs significantly enhance the comprehensive properties of the G/CNT hybrid material, such as large specific surface area, excellent thermal stability, and high electrical conductivity. Consequently, the microwave absorption properties of G/CNT are significantly enhanced compared with CNTs. This work provides a feasible pathway to synthesize high-performance covalently bonded G/CNT hybrids.