Abstract
• Emodin are anchored on graphene to form organic molecules electrode. • The optimal electrode achieves high specific capacitance and good rate capability. • The assembled ASC obtains the high energy density and power density. • The two ASC devices in series lights a red light-emitting diodes. Emodin is a natural anthraquinone derivative and contains abundant hydroxyl and carbonyl groups, which has high redox activity. As guest molecules, Emodin molecules were anchored on graphene sheet (GNS) by simple one-step reflux method. In the three-electrode system, the optimal composite electrode material (E@GNS) obtained the high specific capacitance of 338.9 F g −1 at 5 mV s −1 and excellent rate capability in 1 mol L −1 H 2 SO 4 . Finally, an asymmetric supercapacitor (ASC) was fabricated by using E@GNS as negative electrode and Caffeic acid non-covalently modified graphene hydrogel (GH-CFA) as positive electrode, respectively. The device achieved the energy density of 32.8 Wh kg −1 along with power density of 0.8 kW kg −1 , and a light-emitting diode (LED) could be light up by two ASCs in series. To compare with the performance of ASC, we also assembled symmetric supercapacitor based on E@GNS, proving that the good matching of positive and negative electrode materials could make the supercapacitor exhibit the best capacitive performance.
Published Version
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