Metal–Organic Coordination Polymer to Prepare\nDensity Controllable and High Nitrogen-Doped Content Carbon/Graphene\nfor High Performance Supercapacitors

Abstract

Design\nand preparation of carbon-based electrode material with\nhigh nitrogen-doping ratio and appropriate density attract much interest\nfor supercapacitors in practical application. Herein, three porous\ncarbon/graphene (NCG_Cu, NCG_Fe, and NCG_Zn) with high doping ratio of nitrogen have been prepared via directly\npyrolysis of graphene oxide (GO)/metal–organic coordination\npolymer (MOCP) composites, which were formed by reacting 4,4′-bipyridine\n(BPD) with CuCl₂, FeCl₃, and ZnCl₂, respectively. As-prepared NCG_Cu, NCG_Fe and\nNCG_Zn showed high nitrogen doping ratio of 10.68, 12.99,\nand 11.21 at. %; and high density of 1.52, 0.84, and 1.15 g cm^–3, respectively. When as-prepared samples were used\nas supercapacitor electrodes, NCG_Cu, NCG_Fe and\nNCG_Zn exhibited high gravimetric specific capacitances\nof 369, 298.5, 309.5 F g^–1, corresponding to high\nvolumetric 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\ngood cycling stability, nearly 100% of the capacitance retained after\n1000 cycles even at a large current density of 10 A g^–1. It is expected that the provided novel strategy can be used to\ndevelop electrode materials in high performance energy conversion/storage\ndevices.