Vicinal Co atom-coordinated Fe–N–C catalysts to boost the oxygen reduction reaction

Abstract

Fe–N–C catalysts have achieved great progress in terms of catalytic activity for the oxygen reduction reaction (ORR) in acidic conditions, but their unsatisfactory durability has not been improved yet. Here, we rationally introduce Co atoms adjacent to Fe–N₄ moieties to construct a dual-metal site catalyst with FeCoN₆ configuration, which has been validated by synchrotron X-ray absorption spectroscopy. Spectroscopic analysis reveals that the vicinal effect of Co atoms on the Fe–N₄ active site increases the electron density around the Fe center, which confers extraordinary durability with only ∼11 mV decay in half-wave potential (E_1/2) after a 10 000 cycle durability test and superb ORR activity with a E_1/2 of 0.842 V. Theoretical calculations reveal that the vicinal Co atom not only prevents Fe dissolution by inhibiting *O(OH) intermediate formation but also facilitates the desorption of *OH from Fe–N₄, simultaneously boosting the ORR durability and activity.