Nitrogen-Doped Graphene with
Pyridinic Dominance as
a Highly Active and Stable Electrocatalyst for Oxygen Reduction
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Abstract
The nitrogen-doped graphene (NG)
with dominance of the pyridinic-N
configuration is synthesized via a straightforward process including
chemical vapor deposition (CVD) growth of graphene and postdoping
with a solid nitrogen precursor of graphitic C<sub>3</sub>N<sub>4</sub> at elevated temperature. The NG fabricated from CVD-grown graphene
contains a high N content up to 6.5 at. % when postdoped at 800 °C
but maintains high crystalline quality of graphene. The obtained NG
exhibits high activity, long-standing stability, and outstanding crossover
resistance for electrocatalysis of oxygen reduction reaction (ORR)
in alkaline medium. The NG treated at 800 °C shows the best ORR
performance. Further study of the dependence of ORR activity on different
N functional groups in these metal-free NG electrodes provides deeper
insights into the origin of ORR activity. Our results reveal that
the pyridinic-N tends to be the most active N functional group to
facilitate ORR at low overpotential via a four-electron pathway