Organic multi-electron redox couple-induced functionalization for enabling ultrahigh rate and cycling performances of supercapacitors

In the present work, the danthron molecule (1,8-dihydroxyanthraquinone, DT) with multi-electron redox centers as a novel organic electrochemically active material for supercapacitors has been decorated on reduced graphene oxide nanosheets (RGNs) via a facile one-step reflux method. The resultant danthron functionalized RGNs (DT-RGNs) composite electrode material not only provided a fast and reversible 4e(-)/4H(+) redox reaction because of two types of redox-active organic functional groups (carbonyl and hydroxyl) in DT, but also preserved the unique electrode architecture with the required conductivity of the graphene nanosheets. In the three-electrode system, the optimized electrode (DT-RGNs 3 : 5) exhibited an excellent capacitance of 491 F g(-1) at 1 A g(-1) which is three times higher than that of bare RGNs. Most importantly, the DT-RGNs electrode showed an ultrahigh rate capability of 80.8% capacitance retention at 100 A g(-1) and a superior electrochemical stability of 98.8% after 10 000 cycles at 10 A g(-1), outstripping a great amount of reported organic and inorganic electrodes. Meanwhile, the effect of intramolecular and/or intermolecular hydrogen bonds between carbonyl and hydroxyl on the electrochemical properties of the DT-RGNs electrode was investigated. Finally, the novel symmetric supercapacitor (DT-RGNs SSC) was assembled to evaluate the actual energy storage properties of electrode materials.