Fe/N Codoped Carbon Nanocages with Single-Atom Feature as Efficient Oxygen Reduction Reaction Electrocatalyst

The electrochemical kinetics of oxygen reduction reaction (ORR) determines the energy conversion efficiency of fuel cells and metal–air batteries. Thus, developing efficient and low-cost electrocatalysts for the ORR has attracted mounting attention. Herein, a facile synthetic route is presented to achieve atomic dispersion of Fe–Nx species in N doped porous carbon nanocages, resulting in a single-atom ORR electrocatalyst. The obtained Fe/N codoped carbon nanocages exhibit a comparable half-wave potential (0.82 V) and higher limiting current density compared to the commercial Pt/C electrocatalyst. In addition, by using it as air electrode electrocatalyst, the assembled Zn–air battery device shows a specific capacity of 705 mAh g–1 at 5 mA cm–2 and a negligible voltage loss after continuous operation for 67 h. The superior performance of Fe/N codoped carbon nanocages is attributed to the porous structure and the synergetic effect of atomically dispersed Fe–Nx species and N doping.