Abstract
Graphitic materials are essential in energy conversion and storage because of their excellent chemical
and electrical properties. The strategy for obtaining functional graphitic materials involves graphite
oxidation and subsequent dissolution in aqueous media forming graphene-oxide nanosheets (GN).
Restacked GN contain substantial intercalated water that can react with heteroatom dopants or the
graphene lattice during reduction. Here we demonstrate that removal of intercalated water using simple
solvent treatments causes significant structural reorganization substantially impacting the oxygen
reduction reaction (ORR) activity and stability of nitrogen-doped graphitic systems. Contrasting reports
describing ORR activity of GN-based catalysts in alkaline electrolytes, we demonstrate superior activity
in acidic electrolyte with onset potential of ~0.9 V, half-wave potential (E翻) of 0.71 V, and selectivity
for four-electron reduction >95%. Further, durability testing showed E翻 retention >95% in N2- and O2-
saturated solutions after 2000 cycles demonstrating highest ORR activity and stability reported to date
for GN-based electrocatalysts in acidic media.
