Hydrophobic-aerophilic composite catalysts enable the fast-charging Zn-air battery to operate 1200 h at 50 mA cm−2

Abstract

High-efficient bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are central to Zn-air batteries (ZABs). However, the bifunctional activity of catalysts is still unsatisfactory, which restricts the fast-charge performance of ZABs. In this work, we constructed a hydrophobic-aerophilic bifunctional catalyst, where CoFe nanoparticles (NPs) and single atoms (SAs) are separately loaded on zeolite imidazolate fame (ZIF)-derived carbon and hollow carbon tubes respectively (CoFe NP@SA). Thereinto, CoFe SAs are known to be highly active to ORR reaction. Moreover, the in-situ Raman illustrates that CoFe NPs are transformed to CoOOH and FeOOH by electrochemical reconstruction, which can boost the OER activity. Furthermore, the hydrophobic-aerophilic surface can repel water molecules to create abundant solid–liquid-gas three-phase reaction interfaces and expose active sites, which consequently promote the diffusion of reactive molecules/ions across the interface and the oxygen adsorption. Thus, the CoFe NP@SA catalyst exhibit an ultralow ORR/OER potential gap of 0.6 V. After assembled as zinc-air battery (ZAB), it demonstrates a low charge potential (2.09 V) under a high current density of 50 mA cm⁻² with the 1200-hour durability. This strategy paves the way to realize the high-power-density and fast-charging ZABs.