Facile synthesis of transition metal (M = Cu, Co) oxide grafted graphitic carbon nitride nanosheets for high performance asymmetric supercapacitors

Among the existing energy storage devices, supercapacitors have attracted an increasing attention in recent years. In this work, two different transition metal (M = Cu, Co) oxides grafted on graphitic carbon nitride (GCN) nanosheets were successfully synthesized through single-step pyrolysis assisted route. The as-prepared nanocomposites exhibit high specific surface area and demonstrate the excellent electrochemical performances for supercapacitors. The CoO/GCN-NS and CuO/GCN-NS electrodes facilitate rapid Faradaic reaction in aqueous 6.0 M KOH electrolyte, and deliver the highest specific capacitance of 458 F g-1 and 154.5 F g-1 at 0.5 A g-1. The CoO/GCN-NS and CuO/GCN-NS electrodes were integrated with commercial activated carbon (AC) to fabricate asymmetric supercapacitors, which exhibits high specific capacitance of 124.75 F g-1 (CoO/GCN-NS//AC) and 84.28 F g-1 (CuO/GCN-NS//AC) at 0.5 A g-1 and higher cycling performance (about 96% retention after 2000 cycles). An asymmetric supercapacitor device could power a light emitting diode (LED), demonstrating that metal oxide/GCN-NS is a potential electrode material for energy storage applications.