Possible Oxygen Reduction Reactions for Graphene Edges from First Principles

N-doped carbon-based nanomaterials are attracting a great interest as promising Pt-free electrode catalysts for polymer electrolyte fuel cells (PEFCs). In this computational study, we demonstrate that N-doped graphene edges can exhibit enhanced catalytic activity toward oxygen reduction reactions by controlling their electron-donating and -withdrawing abilities and basicity, resulting in higher selectivity of 4e(-) reduction via inner- and outer-sphere electron transfer at edges under acidic conditions, respectively. Our simulations also show that 2e(-) reduction occurs selectively in the presence of pyridinic N next to carbonyl O at zigzag edges. This study thus rationalizes the roles of doped N in graphenelike materials for oxygen reduction reactions.