Influence of doping level on the electrocatalytic properties for oxygen reduction reaction of N-doped reduced graphene oxide

Abstract Reduced Graphene Oxide (rGO) doped with different nitrogen (N) concentrations (5, 10, and 15 parts in weight) were successfully synthesized via hydrothermal conditions, from graphene oxide (GO) and 3-amino-1,2,4-triazole (amitrole) to obtain N5-rGO, N10-rGO, and N15-rGO. These N-doped materials were characterized and evaluated for the first time as catalysts for the oxygen reduction reaction (ORR). The physicochemical characteristics confirmed the simultaneous N-doping and reduction processes with a turbostratic re-stacking of graphene layers. Nitrogen was successfully introduced as a mix of pyridine-N, amine like-N, pyrrolic-N, and quaternary bonding species into the carbon lattice. The N content were 8.1, 9.9, and 10.5 at.% for N5-rGO, N10-rGO, and N15-rGO. High catalytic activity was demonstrated in alkaline media with an onset potential of ~0.88 V and high current density (3.9 mA cm−2) for N15-rGO, leading the ORR via the 4-electron transfer pathway. The results demonstrated that the amine like-N species enhance the ORR catalytic activity in addition to pyridinic and quaternary.