Electronic interaction coupling of Fe-ZrO2 enables efficient and stable ORR electrocatalyst for long-cycling Zn-air battery

Metallic Fe single atom is an efficient catalyst for rechargeable zinc-air batteries (ZABs), but faces problems such as easy deactivation and instability in use. Here, we report a stable Fe-ZrO₂ electrocatalyst for oxygen reduction reaction (ORR) catalysis. Atomically coupled Fe-O-Zr heterointerfaces are formed by embedding Fe nanodots (around 18 nm) into ZrO₂ nanoparticles dispersed in nitrogen doped bubble-like porous carbon nanofibers (PCNFs). In this structure, Fe can share electrons with ZrO₂ to form interfacial coupling Fe-O-Zr bond as a bridge for charge transfer, in which ZrO₂ acts as electron promoter to facilitate electron transfer from Fe to the interface, thereby inhibiting the rapid deactivation of Fe and accelerating the activation and conversion of intermediate adsorbates. As a result, the electrocatalyst with a high loading of Fe (7.96 wt%) achieves a high half-wave potential of 0.868 V, with 95.3% of retained activity after cycling for 39600 s. The ZABs show stable open-circuit voltages and high capacities of 823.9 mA·cm⁻², and can stably run 1560 cycles at 10 mA·cm⁻² with a round-trip efficiency of 51%, exhibiting superior cycling stability.