Ir cluster/Fe2O3 heterostructures on carbon nanotubes boosting oxygen evolution/reduction reactions for flexible Zn-air battery

The development of bifunctional and universal-pH electrocatalysts for oxygen evolution (OER) and oxygen reduction reactions (ORR) is crucial in the field of metal-air batteries. In this study, we succeed in boosting the OER and ORR activity in both acidic and alkaline conditions by designing an Ir cluster/Fe 2 O 3 @CNTs heterostructures. The resulting material exhibited excellent lower overpotentials of 300 ​mV and 298 ​mV in 0.5 ​M ​H 2 SO 4 and 1.0 ​M KOH media at a current density of 10 ​mA ​cm −2 . Theoretical calculations suggest that Ir cluster enhances the surface electron emission ability by its proximity to the Fermi level, which prompts electron transfer from the Ir layer to Fe 2 O 3 . This process effectively increases the surface electron density and consequently improves the likelihood of electron emission. The fabricated rechargeable flexible Zn-air battery demonstrated excellent cycling stability over 330 ​h at a current density of 2 ​mA ​cm −2 with a capacity retention rate of 58.2 ​%, highlighting its role as the state-of-the-art bifunctional oxygen electrocatalyst.