Hierarchically porous carbon nanosheets derived from Moringa oleifera stems as electrode material for high-performance electric double-layer capacitors

摘要

A facile one-step pyrolysis route for the synthesis of hierarchically porous carbon nanosheets (PCNSs) derived from Moringa oleifera stems (MOSs) is reported, in which no post-activation-process in needed. The as-prepared PCNSs possesses unique porous nanosheet morphology with high specific surface area of ca. 2250 m(2) g(-1), large pore volume of ca. 2.3 cm(3) g(-1), appropriate porosity as well as heteroatom doping (N and O), endowing outstanding electrochemical properties as electrode material for highperformance supercapacitors. The PCNS-based electrodes are investigated in various aqueous electrolytes including 1.0 M Na2SO4, 1.0 M H2SO4, and 6.0 M KOH. The PCNSs exhibit a maximum specific capacitance of ca. 283 F g(-1) (0.5 A g(-1)), excellent rate capability (ca. 72% of capacitance retention even at an ultrahigh current density of 50 A g(-1)), and a tremendous long-term cycling stability in the three electrode system. Moreover, the as-assembled PCNS-based symmetric supercapacitor shows a high energy density of ca. 25.8 Wh kg(-1) (in 1.0 M Na2SO4 electrolyte) and remarkable long-term cycling stability (almost no capacitance fade in aqueous electrolytes), indicating the promising of the as-prepared PCNSs for electrochemical energy storage and conversion. (C) 2017 Elsevier B.V. All rights reserved.