Tailoring FeN4 Sites with Edge Enrichment for Boosted Oxygen Reduction Performance in Proton Exchange Membrane Fuel Cell

Transition metal atoms with corresponding nitrogen coordination are widely proposed as catalytic centers for the oxygen reduction reaction (ORR) in metal-nitrogen-carbon (M-N-C) catalysts. Here, an effective strategy that can tailor Fe-N-C catalysts to simultaneously enrich the number of active sites while boosting their intrinsic activity and utilization is reported. This is achieved by edge engineering of FeN4 sites via a simple ammonium chloride salt-assisted approach, where a high fraction of FeN4 sites are preferentially generated and hosted in a graphene-like porous scaffold. Theoretical calculations reveal that the FeN4 moieties with adjacent pore defects are likely to be more active than the nondefective configuration. Coupled with the facilitated accessibility of active sites, this prepared catalyst, when applied in a practical H-2-air proton exchange membrane fuel cell, delivers a remarkable peak power density of 0.43 W cm(-2), ranking it as one of the most active M-N-C catalysts reported to date. This work provides a new avenue for boosting ORR activity by edge manipulation of FeN4 sites.