Exploration of the Active Center Structure of Nitrogen-Doped Graphene for Control over the Growth of Co3O4 for a High-Performance Supercapacitor

Nitrogen-doped graphene sheets with different active center structures, such as amine N, quaternary N, pyridinic N, or pyrrolic N atoms, were successfully fabricated using targeted nitrogen precursors and a designed annealing process. Then, the nitrogen-doped graphene with a different structure is used as the active center for the growth of Co 3 O 4 nanoparticles. The investigation results reveal that the interaction between loaded Co 3 O 4 particles and amine N atoms doped in graphene sheets is stronger than those of quaternary N, pyridinic N, or pyrrolic N atoms, and leads to a smaller particle size of Co 3 O 4 and a high specific surface area of composite electrodes which perform with better electrochemical behavior. The Co 3 O 4 /N-RGO 550 °C dominated with amine N atoms exhibits the highest capacitance of 3553 and 1967 F g –1 at 1 and 15 A g –1, respectively, which are apparently higher values than those of the other Co 3 O 4 composite grown on the nitrogen-doped graphene dominated with pyridinic N, pyrrolic N, or quaternary N atoms, respectively, and those of previously reported Co 3 O 4 with different morphology or Co 3 O 4 composite materials. Moreover, an electrode prepared from Co 3 O 4 /N-RGO 550 °C dominated with amine N atoms also has an excellent cycling stability with >90% capacity retention after 3000 cycles at 5 A g –1 . The stronger interaction between Co 3 O 4 and amine N atoms doped in graphene sheets, which facilitate the formation of smaller Co 3 O 4 particle sizes to form higher specific surface and desired pore size distribution to enhance the capacitance and make the Co 3 O 4 /N-RGO 550 °C extremely stable for capacitive energy storage, suggest the potential usage of the Co 3 O 4 /N-RGO 550 °C composite as high-supercapacitor electrode materials.