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-N-x 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-N-x species and N doping.