Rapid synthesis of nitrogen-doped graphene by microwave heating for oxygen reduction reactions in alkaline electrolyte

Abstract

Nitrogen-doped graphene (NG) with a nitrogen content from 4.05 wt% to 5.47 wt% was rapidly prepared via microwave heating of graphene under NH 3 flow. The as-synthesized NG samples were then used as electrocatalysts in the oxygen reduction reaction (ORR) in alkaline solution. The NG samples showed excellent ORR catalytic activity with an onset potential of 0.17 V, which is comparable to that of commercial Pt/C electrocatalyst (0.21 V). The structure, composition, and nitrogen species of the NG samples were examined by transmission electron microscopy, Raman spectroscopy, elemental analysis and X-ray photoelectron spectroscopy. The onset potential increases with the content of graphite nitrogen in the NG samples, indicating that graphite nitrogen might be the main factor controlling the performance of the NG samples in the ORR. The results showed that NG prepared by rapid microwave heating is a promising ORR catalyst for fuel cells. Nitrogen-doped graphene was rapidly synthesized via microwave heating by doping nitrogen atoms from ammonia molecules into graphene sheets.