Effects of pyridine and pyrrole moieties on supercapacitive properties of imine-rich nitrogen-doped graphene

In this study, a series of imine-rich nitrogen-doped graphenes (IR-NGs), where pyridine and pyrrole functionalities were selectively incorporated in the near vicinity of imine groups, were synthesized, and used as electrode materials for supercapacitors. The facile acid-catalyzed dehydration reactions of graphene oxide (GO) with 6-aminoquinoline and 5-aminoindole could produce specific pyridine- and pyrrole-modified IR-NGs, respectively, denoted as PD-NG and PR-NG, respectively. In addition, aniline was reacted with GO to obtain the reference AN-NG, which only contains imine groups. The compositional and structural features of these three IR-NG compounds were confirmed using various spectroscopic and microscopic measurements. The specific capacitances of these IR-NGs in 6 M aqueous KOH solution as an electrolyte gradually increased as follows: PD-NG < AN-NG < PR-NG. The highest capacitance of 174 F g−1 was obtained from PR-NG at the current density of 1.0 A g−1, whereas the capacitances of PD-NG and AN-NG were limited to 125 and 138 F g−1, respectively, under the same conditions. These results indicated that the contributions of the pyridine and pyrrole moieties on the supercapacitive properties of IR-NGs were significant.