Metal–Organic Coordination Polymer to Prepare Density Controllable and High Nitrogen-Doped Content Carbon/Graphene for High Performance Supercapacitors

Abstract

Design and preparation of carbon-based electrode material with high nitrogen-doping ratio and appropriate density attract much interest for supercapacitors in practical application. Herein, three porous carbon/graphene (NCG_Cu, NCG_Fe, and NCG_Zn) with high doping ratio of nitrogen have been prepared via directly pyrolysis of graphene oxide (GO)/metal-organic coordination polymer (MOCP) composites, which were formed by reacting 4,4'-bipyridine (BPD) with CuCl₂, FeCl₃, and ZnCl₂, respectively. As-prepared NCG_Cu, NCG_Fe and NCG_Zn showed high nitrogen doping ratio of 10.68, 12.99, and 11.21 at. %; and high density of 1.52, 0.84, and 1.15 g cm^-3, respectively. When as-prepared samples were used as supercapacitor electrodes, NCG_Cu, NCG_Fe and NCG_Zn exhibited high gravimetric specific capacitances of 369, 298.5, 309.5 F g^-1, corresponding to high volumetric specific capacitances of 560.9, 250.7, 355.9 F cm^-3 at a current density of 0.5 A g^-1, as well as good cycling stability, nearly 100% of the capacitance retained after 1000 cycles even at a large current density of 10 A g^-1. It is expected that the provided novel strategy can be used to develop electrode materials in high performance energy conversion/storage devices.