Exploration of the active center structure of nitrogen-doped graphene-based catalysts for oxygen reduction reaction
Potts, Jeffrey R.
Poh, Chee Kok
Ruoff, Rodney S.
Date of Issue2012
School of Physical and Mathematical Sciences
We present two different ways to fabricate nitrogen-doped graphene (N-graphene) and demonstrate its use as a metal-free catalyst to study the catalytic active center for the oxygen reduction reaction (ORR). N-graphene was produced by annealing of graphene oxide (G-O) under ammonia or by annealing of a N-containing polymer/reduced graphene oxide (RG-O) composite (polyaniline/RG-O or polypyrrole/ RG-O). The effects of theNprecursors and annealing temperature on the performance of the catalyst were investigated. The bonding state of the N atom was found to have a significant effect on the selectivity and catalytic activity for ORR. Annealing of G-O with ammonia preferentially formed graphitic N and pyridinic N centers, while annealing of polyaniline/RG-O and polypyrrole/RG-O tended to generate pyridinic and pyrrolic N moieties, respectively.Most importantly, the electrocatalytic activity of the catalyst was found to be dependent on the graphitic N content which determined the limiting current density, while the pyridinicNcontent improved the onset potential forORR.However, the totalNcontent in the graphene-based non-precious metal catalyst does not play an important role in the ORR process.
Energy & environmental science