▎ 摘　　要

Nitrogen-doped reduced graphene oxide (N-rGO) has been synthesized using a simple, efficient method combining instant thermal exfoliation and covalent bond transformation from a melamine-graphene oxide mixture. The capacitive performance of N-rGO has been tested in both aqueous (0.5 M H2SO4) and organic (1 M tetraethyl-ammonium tetrafluoroborate (TEABF(4)) in propylene carbonate (PC)) electrolytes, which are compared with those obtained from thermal-reduced graphene oxide (T-rGO) and chemical-reduced graphene oxide (C-rGO). The contributions of scan-rate-independent (double-layer-like) and scan-rate-dependent (pseudo-capacitance-like) capacitance of all reduced graphene oxides in both aqueous and organic electrolytes were evaluated and compared. The results show that relatively rich oxygen-containing functional groups on C-rGO form significant ion-diffusion barrier, resulting in worse electrochemical responses in organic electrolyte. By contrast, the N-doped structures, large surface area, and lower density of oxygen-containing groups make N-rGO become a promising electrode material for organic electric double-layer capacitors (EDLCs). The capacitance rate-retention of N-rGO reaches 71.1% in 1 M TEABF(4)/PC electrolyte when the scan rate is elevated to 200 mVs(-1), demonstrating that N-rGO improves the relatively low-power drawback of EDLCs in organic electrolytes. The specific energy and power of a symmetric N-rGO cell in the organic electrolyte reach 25 Wh kg(-1) and 10 kW kg(-1), respectively. (C) 2014 Elsevier B.V. All rights reserved.