Chapter 4. Design of Graphene/CNT-based Nanocomposites: A Stepping Stone for Energy-related Applications

The regular requirement for excellent, low weight, cost-effective, and durable materials have been the driving force for the investigation of novel materials. The exploration of carbon-based materials such as graphene has gained extensive research consideration due to its outstanding properties. Graphene is the thinnest (2D carbon) material in the universe with high charge carrier mobility, excellent chemical and mechanical stability, superb surface area, and good optical transparency. Therefore, it is expected to be an excellent and promising candidate in current material science research and nanotechnology. However, pristine graphene sheets are not suitable as flexible transparent conductors and many more applications due to the presence of defects, agglomeration behavior, and grain boundaries, while having high sheet resistance which can be broken easily and facing objection for designing controlled functionality. One decisive approach to explore the ability of graphene is to architect a graphene composite as a perfect building block for controllable functionalization with another carbon material with logical C–C junction formation. In this context, carbon nanotubes (CNTs) act as reinforcing bars that not only restrict the agglomeration behavior but also generate the synergistic effect between them as well as a bridge between different crystalline domains with outstanding chemical and physical properties. Therefore, this article aims to present readers with a better understanding of hybrid carbon design by creating covalent interconnection between CNT and graphene for energy-related applications.