A highly capacitive Graphene/Multiholed N‐CNTs hybrid evolved from black humate‐Co‐melamine precursor

Black humic acid (BA) is a black mixture of organic macromolecules isolated from humic acid, which has a greater potential for graphene transformation than fulvic acid and ulmic acid because of more and larger aromatic units and higher molecular weights exceeding 5000 Dalton. Here, chemically bonded BA‐Co‐Melamine precursors are initially constructed using different BA fractions as substrate, Co2+ as bridge bond and melamine as ligand. A series of Graphene/N‐CNTs hybrids (GNCs) is eventually synthesized after the precursor pyrolysis. Resultantly, Fraction Ⅰ, separated at a pH value of 4.16, plays a significant role on constructing the BA‐Co‐Melamine precursor and further producing multiholed GNCs. Due to abundant CNTs, rich mesopores, moderate nitrogen incorporation and a certain graphitized assembly structure, the prepared GNC‐Ⅰ‐b has high capacitance performances. The assembled AC//GNC‐Ⅰ‐b supercapacitor has high specific capacitance (147 F g‐1 at 0.5 A g‐1), rate capability, cycling stability and energy density (16.8 Wh kg‐1 at 14.4 KW kg‐1). The 2032 coin‐type Li//GNC‐Ⅰ‐b half‐cell has high initial discharge capacity (759 mAh g‐1 at 0.03 A g‐1), initial Coulombic efficiency (81.8%), rate performance and cycling stability. Hence, the GNC is a favorable high‐performance carbon material hopefully applied as electrode materials of supercapacitors and LIBs.