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Graphene quantum dots (GQDs) have attracted tremendous research interest due to the unique properties associated with both graphene and quantum dots. Here, a new application of GQDs as ideal electrode materials for supercapacitors is reported. To this end, a GQDs//GQDs symmetric micro-supercapacitor is prepared using a simple electro-deposition approach, and its electrochemical properties in aqueous electrolyte and ionic liquid electrolyte are systematically investigated. The results show that the as-made GQDs micro-supercapacitor has superior rate capability up to 1000 V s−1, excellent power response with very short relaxation time constant ( τ0 = 103.6 μs in aqueous electrolyte and τ0 = 53.8 μs in ionic liquid electrolyte), and excellent cycle stability. Additionally, another GQDs//MnO2 asymmetric supercapacitor is also built using MnO2 nanoneedles as the positive electrode and GQDs as the negative electrode in aqueous electrolyte. Its specific capacitance and energy density are both two times higher than those of GQDs//GQDs symmetric micro-supercapacitor in the same electrolyte. The results presented here may pave the way for a new promising application of GQDs in micropower suppliers and microenergy storage devices. [ABSTRACT FROM AUTHOR]

A new application of graphene quantum dots (GQDs) as an ideal electrode material for supercapacitors is explored by X.‐B. Yan and co‐workers. On page 4111 they build a GQD//GQD symmetric micro‐supercapacitor and a GQD//MnO2 asymmetric supercapacitor. Both devices show excellent rate capabilities, exceptionally high‐frequency responses, and long‐term cycle stability. [ABSTRACT FROM AUTHOR]