Synthesis of N-doped graphene nanosheets and its composite with urea choline chloride ionic liquid as a novel electrode for supercapacitor

Reduced graphene oxide (RGO) and graphene oxide (GO) nanosheets are synthesized via one pot electrochemical method using graphite rode in super saturated urea choline chloride and water. GO and ionic liquid are annealed using thermal method to obtain NRGO. Microstructure measurements present that most nitrogen doped on the edge of the surfaces of nanosheets. X-ray photoelectron spectroscopy revealed that nitrogen is grafted to the basal plane of graphene, with about 6.2 atom % nitrogen coverage. Nitrogen-doped RGO is evaluated as a supercapacitor electrode. The NRGO in ionic liquid has an exceptionally high capacitance of 383 F g(-1) in 6 M of KOH and two-electrode configuration at current density of 1Ag(-1). In comparison, an analogous NRGO and RGO bear low capacitance of 321 and 196 F g(-1), demonstrating the importance of ionic liquid in the charge storage process. The method is easily scaled from milligram to multigram quantities of N-doped RGO and ionic liquid. (C) 2017 Elsevier B.V. All rights reserved.