Cascade Limiting Strategy for Constructing Single-Atomic Catalysts on Self-Supporting Hydrophobic Edge-Rich Graphene Membrane as Zn-Air Battery Cathode

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.