The hybridization of 1D CNT with 3D graphene structure has recently attracted attention owing to their large specific surface area, high electronic conductivity, and structural integrity. These features of the hierarchical architectures can provide synergic affect on the energy storage such as supercapacitors, fuel cells and lithium-ion batteries. In addition, the performance has been further improved by doping with different heteroatoms like sulphur, boron, phosphorous and nitrogen because they can play a vital role in changing the local electronic density leading to improved electronic conductivity.

 In this work, we synthesize 3D nitrogen (N)-doped reduced graphene oxide (rGO) branched by CNT for applications into lithium ion batteries. The hierarchical architecture consisting of the CNT branching on 3D N-doped rGO was characterized by SEM and TEM images. Iron oxide nanoparticles acted as the catalyst for the growth of CNT as well as active materials for lithium storage. The crystalline structure of iron oxide nanoparticles and restacking inhibition of rGO were confirmed by the XRD analysis. The BET data indicate the presence of mesoporous structure with average pore diameter of 21 nm with 400 m²/g surface area.  The XPS data identified the presence, composition, and bonding configuration of carbon, iron, nitrogen and oxygen. The electrochemical properties were characterized by cyclic voltametry, impedance spectroscopy, and galvanic charge/discharge curve for lithium ion battery application.