Atomically-dispersed Fe sites embedded in nitrogen-doped graphene as highly efficient oxygen reduction electrocatalysts

The development of cost-effective and highly active catalysts for the oxygen reduction reaction (ORR) is crucial for the successful commercialization of Zn-air batteries. Single-atom catalysts are considered to be the most promising alternatives to Pt-based catalysts on account of their high atomic utilization and adjustable coordination environment, but their activity and durability are not ideal. Herein, a porous nitrogen-doped graphene with atomically-dispersed Fe sites (Fe SAs/NG) is developed by utilizing g-C3N4 as the nitrogen source. The Fe SAs/NG exhibits superior ORR property in alkaline electrolyte with a high half-wave potential (E1/2 = 0.883 V vs. RHE) and remarkable stability, mainly due to atomically-dispersed Fe sites, abundant N species, and porous structure. Moreover, the Fe SAs/NG-based Zn-air battery achieves the maximum discharge power density of 272.6 mW cm−2, surpassing that of benchmark 20% Pt/C catalyst (238 mW cm−2). This study offers a valuable reference for the rational design and synthesis of high efficiency single atom catalysts specifically tailored for Zn-air batteries.