Heteroatoms-doped hierarchically porous graphene as electrode material for supercapacitors with ultra-high capacitance

In this work, a dual-templating pyrolysis strategy is successfully developed to synthesize a highly crumpled graphene (N-TRPG-800). The achievement of the graphene is based on the carbonization of the D (+)-glucosamine hydrochloride and the spatial confinement effect of the graphitic carbon nitride (g-C 3 N 4 ) in the presence of zinc nanoparticles (Zn NPs). During the pyrolysis process, the D (+)-glucosamine hydrochloride first polymerizes into the layers of g-C 3 N 4 , which is derived from melamine. Afterwards, a further increase in pyrolysis temperature leads to the decomposition of g-C 3 N 4 and the generation of reducing NH 3 gas, which eventually resulting in the formation of 2D ultrathin structure and high heteroatoms doping degree. Simultaneously, the volatilization of the Zn NPs also plays a key role in the pore formation and the hierarchical structure generation. As a result, the assynthesized graphene sheets simultaneously possesses hierarchical porous structure, high heteroatoms-doped degree, and large specific surface area (506 m 2 g -1 ). Electrochemical measurements show that the N-TRPG 800 exhibits an ultrahigh supercapacitance of 471 F g -1 at 0.2 A g -1 in a three -electrode mode, approaching the theoretical capacitance of 550 F g -1 of graphene, which is superior to that of the state-of-the-art heteroatomdoped porous carbons in literature.