Utilizing Molybdenum to Tailor the Electronic Structure of Iron Through Electron Complementary Effect for Promoting Oxygen Reduction Activity

Tailoring the electronic structure of later transition metal-based electrocatalysts by incorporating early transition metal based on the electronic complementary effect is anticipated to enhance the electrocatalytic activity. Herein, the modulation of the electronic structure of Fe₃C through the utilization of Mo₂C to promote oxygen reduction reaction (ORR) activity is reported. In situ characterizations combined with theoretical calculations reveal that the electron-donating capability of molybdenum in Mo₂C to the active center of iron in Fe₃C optimizes the adsorption and activation of oxygen. Concurrently, the d-band center of Fe is much closer to the Fermi level, which reduces the energy barrier for the rate-determining step (^*OOH → ^*O), thereby enhancing the ORR activity. In alkaline media, the catalyst delivers a half-wave potential (E_1/2) of 0.89 V and maintains its efficiency with a mere 8 mV decay after 10 000 cycles, surpassing that of Pt/C. Moreover, it can serve as an air cathode in both liquid-state and all-solid-state zinc-air batteries (ZABs) and shows promising applications in portable devices. This work brings an innovative design concept for highly efficient electrocatalysts suitable for advanced energy devices.