Densely accessible single atom Fe sites dispersed on porous carbon as highly stable and active ORR catalyst for PEMFC

Single-atom Fe–N–C catalysts have received ever-growing interest in proton exchange membrane fuel cells (PEMFCs) application for their utmost atomic utilization in oxygen reduction reaction (ORR). However, developing atomically dispersed Fe–N–C catalysts with both satisfactory activity and excellent stability presents great challenges. Herein, a template-activator combined strategy is developed to construct ORR catalysts with densely accessible single-atom Fe sites dispersed on hierarchically porous carbon networks. The optimized catalyst exhibits excellent oxygen reduction activity with a half-wave potential of 0.84 V and surprising stability with 93.6% retention of the initial current density after 24 hours of chronoamperometric test in acidic media. Notably, when assembled in a H2–O2 fuel cell, it shows remarkable long-term durability with only 16% loss in current density during the first 10 hours.