Highly nitrogen-doped graphene anchored with Co3O4 nanoparticles as supercapacitor electrode with enhanced electrochemical performance

Chemical doping with heterogeneous atoms is an effective method to improve the intrinsic properties of graphene. In this work, a competitive type of highly nitrogen-doped graphene (HNG) and its composites hybridized with Co 3 O 4 nanoparticles were synthesized via simple pre-mixing followed by a hydrothermal method. The highest nitrogen content achieved was 11.7%, which endowed the graphene with superior electrochemical performance. Co 3 O 4 nanoparticles could be obtained with an optimal size of approximately 80–100   nm and were homogenously anchored on the graphene nanosheets. Because of the synergy between the highly nitrogen-doped graphene and uniform Co 3 O 4 nanoparticles, the HNG/Co 3 O 4 hybrids exhibited enhanced rate capability and cycling stability, which were considerably higher than those of bare HNG and Co 3 O 4 . As the current density increased from 0.2 to 5   A   g −1 , 80.6% of the specific capacitance was retained. Moreover, over 84.5% of the original specific capacitance was maintained after cycling 1000 cycles. This study has demonstrated the significance of nitrogen doping on the performance of graphene-based materials for supercapacitor electrodes.