A hydrophobic cathode design towards high-stability Zn-air batteries: Coupling FeTAP molecules with self-supporting edge-rich graphene membrane

The agglomerated catalyst powder on electrode's surfaces and the sluggish oxygen diffusion at reaction's interfaces hinder the kinetics of oxygen reduction reactions (ORR) in air cathodes, thereby limiting the performance of Zn-air batteries. Addressing these critical challenges are pivotal for overcoming existing performance bottlenecks. Herein, a self-supporting hydrophobic electrode is prepared by anchoring iron tetrapyridinoporphyrazine (FeTAP) molecules on a 3D edge-rich graphene (ERG) membrane with the help of π–π* stacking. The vertical-aligned graphene sheets in the ERG membrane effectively mitigate the agglomeration of FeTAP molecules and enhance their stability through the coupling effect between ERG sheets and FeTAP molecules. Additionally, the 3D opened hydrophobic ERG membrane not only facilitates rapid oxygen diffusion at numerous gas–liquid-solid reaction interfaces, but also ensures efficient electron transport in high-quality graphene framework. Consequently, as-obtained hydrophobic electrode exhibits superior performance with a positive half-wave potential, rapid reaction kinetics, and decent stability. This work paves an efficient approach for the rational design of high-performance cathodes, emphasizing the integration of gas–liquid-solid reaction interfaces, stable active sites and high-speed electron transfer frameworks for Zn-air batteries.