Fused Heterocyclic Molecule-Functionalized N-Doped Reduced Graphene Oxide by Non-Covalent Bonds for High-Performance Supercapacitors
Liming Xu, Yingying Zhang, Weiqiang Zhou, Fengxing Jiang, Hui Zhang, Qinglin Jiang, Yanhua Jia, Rui Wang, Aiqin Liang, Jingkun Xu, Xuemin Duan
Abstract
Indole molecules with fused heteroaromatic structures can be adsorbed on the N-doped graphene surface through the π–π interaction. Therefore, the indole-functionalized N-doped graphene (InFGN) with mesopores is successfully fabricated by a simple hydrothermal method and subsequent vacuum freeze-drying process. The microstructure, thickness, element composition, pore structure, and electrochemical performance of InFGN are analyzed via SEM, TEM, AFM, BET, UV–vis, FT-IR, XPS, Raman, XRD, and electrochemical technologies. Since the five-membered aromatic heterocycles are electron-rich, the indole molecules fixed on the N-doped graphene surface can repair the structural defects generated by N doping. Electrochemical measurements show that the InFGN electrode highlights an excellent capacitance of 622.3 F g–1 at 2 A g–1 and a durable cycling life of 100.5% after 5000 charging/discharging cycle times. For further practical application, a symmetric device has been assembled by using InFGN electrodes, which realizes high-power and energy densities (18.8–20.6 Wh kg–1 at 800–8000 W kg–1). This study provides a shortcut for building green supercapacitors with enhanced energy storage performance.