Subnanometer Iron Clusters Confined in Porous Carbon Matrix for Highly Efficient Zinc–Air Batteries
Metal coordinates in molecular level are crucial for stabilizing an appropriate electronic configuration for the high-efficiency oxygen reduction reaction (ORR) electrocatalysts. In this work, an excellent platform to realize the decoration of Fe coordinates in subnanometer scale into the nitrogen-doped carbon networks (designated as Fe-Fe©NC) is provided. Results of X-ray absorption spectroscopy investigation confirm the precise configuration of Fe coordinates with Fe-Fe and Fe-N coordinations in molecular level. The newly developed Fe-Fe©NC exhibits superior ORR performance, low discharge–charge voltage gap and a long cycle life in Zn–air batteries. Density functional theory calculation reveals the Fe-Fe coordination in the Fe subclusters favors the 4e- transfer pathway and thus achieves highly active catalytic performance. This work reveals that iron clusters in subnanometer scale provide an optimized electronic structure for the enhanced ORR activity.