Cascade Limiting Strategy for Constructing Single-Atomic Catalysts on Self-Supporting Hydrophobic Edge-Rich Graphene...

Despite the great potential of Fe single-atom catalysts (SACs) to replace platinum-based materials for oxygen reduction reaction (ORR), their synthesis is hindered by the strong tendency of atomic migration/aggregation and uncontrollable substrate etching during fabrication, impeding the direct synthesis of Fe SACs in the rational-designed cathode for Zn-air batteries. Herein, a self-supporting hydrophobic edge-rich graphene (ERG) membrane serves as a conductive carbon skeleton in the air cathode. Through a cascade limiting strategy involving α-D-glucose and melamine, atomically dispersed Fe-NC SACs are synthesized on the surfaces of ERG sheets without substrate damage. Systematic studies confirm that the chelation of Fe ions and their binding to N-species at elevated temperatures are critical to achieving atomic dispersion. By optimizing the molar ratio of α-D-glucose/Fe(III) ions and utilizing the hydrophobic porous framework, the Zn-air battery assembled with ERG@Glu&Fe-40-Mel membrane achieves a peak power density of 132 mW cm^-2 and the enhanced stability compared to that employing commercial Pt/C catalyst.