▎ 摘　　要

Reduced graphene oxide nanosheets modified with rich carbonyl groups (C=O) was obtained through a facile dehydration process by making use of the synergistic effect between phosphoric acid and monosodium phosphate. The product exhibited a high specific capacitance of 413 F g(-1) at the current density of 0.25 A g-1 mainly owing to the high percentage of retained C=O groups which provided reversible pseudocapacitance and favored good dispersion. Additionally, the symmetric supercapacitors based on the modified graphene nanosheets showed high specific capacitance (314.2 Fg(-1) at 1 Ag-1) and superior electrochemical stability with only 5.8% loss of its initial specific capacitance after 10000 cycle tests (at the current densities of 5 Ag-1). The present work proposed an environmentally friendly way in controlling surface structure of reduced graphene oxide which promises great potential of graphene-based electrode materials for high performance energy-storage devices. (C) 2018 Elsevier Ltd. All rights reserved.