Pyridine-enriched graphene sheets for high volumetric performance supercapacitors

Pyridine-enriched graphene sheets (DAP-RGOs) have been successfully prepared at mild reaction conditions from graphene oxide (GO) and 2, 6-diaminopyridine (DAP). High nitrogen content in DAP-RGOs can be readily achieved in a range of 13.1–17.2% by controlling the feed ratios of reactants. The pyridine moieties grafted on the graphene sheets take place a reversible redox reaction and demonstrate faradaic capacitive behavior. Due to its high density (1.59 g cm−3) and reasonable nitrogen content (14.4%), the as-prepared DAP-RGO sample exhibits both high volumetric and gravimetric capacitances of 504 F cm−3 and 317 F g−1 at current density of 0.1 A g−1 in 1 M H2SO4 electrolyte, respectively. Furthermore, the assembled supercapacitor shows an excellent cycling stability with capacitance retention of 90% after 5000 cycles at 2 A g−1.