Nitrogen-functionalization of carbon materials for supercapacitor: Combining with nanostructure directly is superior to doping amorphous element.

Synopsis: Nanostructure combined with porous carbon nanosheets (PCNs/GCNs-5) and amorphous element doped porous carbon nanosheets (PCNs/N) were prepared by changing the nitrogen source in the thermal polymerization process. Compared with the latter, PCNs/GCNs-5 has high active nitrogen ratio and mesopore ratio facilitating the pseudo-capacitance reaction and ion transport to ensure the better power and energy density, and the smaller erosion of the carbon skeleton by the nanostructure insures the cyclic stability of PCNs/GCNs-5. [Display omitted] • Nanostructure combined with porous carbon nanosheets (PCNs) were prepared by simple thermal polymerization and carbonization. • The microstructure and energy storage mechanism of amorphous N doped PCNs and nanostructure N combined with PCNs were compared. • The relationship between g-C 3 N 4 self-decomposition and pore structure, defects and surface morphology of carbon materials was investigated. • Through theoretical calculation, the different rules of N types variation in different structures are verified. Just how heteroatomic functionalization enhances electrochemical capacity of carbon materials is a recent and widely studied field in scientific research. However, there is no consensus on whether combining with heteroatom-bearing nanostructures directly or doping amorphous elements is more advantageous. Herein, two kinds of porous carbon nanosheets were prepared from coal tar pitch through anchoring graphitic carbon nitride (PCNs/GCNs-5) or doping amorphous nitrogen element (PCNs/N). The structural characteristics and electrochemical properties of the two PCNs were revealed and compared carefully. It can be found that the amorphous nitrogen of PCNs/N will have a grievous impact on its carbon skeleton network, resulting in reduced stability in charge and discharge process, while the structural collapse of carbon network could be avoided in PCNs/GCNs-5 by the heteroatoms in the form of nanostructure. Particularly, PCNs/GCNs-5 exhibits extremely high specific capacity of 388 F g−1 at 1 A g−1, and splendid the capacitance retention rate of 98% after 10,000 cycles of charge and discharge, which are overmatch than the amorphous nitrogen doped carbon materials reported recently and PCNs/N. The combining strategy with nanostructure will inspire the design of carbon materials towards high-performance supercapacitor. [ABSTRACT FROM AUTHOR]