▎ 摘　　要

Here, the fast and shorter duration synthesis route was proposed for the production of N-doped graphene by supercritical fluid method involving ammonium oxalate as a source of nitrogen. Within the different proportions of graphene oxide and nitrogen source, the nitrogen-doped graphene formed from ammonium oxalate having nitrogen content of 3.3wt% showed an enriched specific capacitance of 274Fg(-1) at 1A/g in 20% KOH electrolyte. The long-term stability results obtained from galvanostatic charge-discharge in ammonium oxalate-based N-doped graphene revealed that 90% specific capacitance retention was achieved up to 10,000cycles at 10A/g. To examine the device proficiency, a full cell was fabricated and the performance was evaluated in two different approaches. Among the different media in aqueous electrolytes, the fabricated symmetric supercapacitor has achieved a maximum specific capacitance value of 160F/g at 1A/g in alkaline medium (20% KOH solution). Between 20% KOH solution and 1M NaClO4 solution in acetonitrile, the fabricated symmetric supercapacitor exhibits an energy density of 26.5Wh/kg as well as 5.5Wh/kg in 1M sodium perchlorate in acetonitrile solution and 20% KOH solution, respectively.