Boosting oxygen evolution electrocatalysis via CeO₂ engineering on Fe₂N nanoparticles for rechargeable Zn-air...

In the process of developing low-cost and high-performance bifunctional electrocatalysts, rational selection of catalytic components and tuning of their electronic structures to achieve synergistic effects is a feasible approach. In this work, CeO₂ was composited into Fe/N-doped carbon foam by a molten salt method to improve the electrocatalytic performance of the composite catalyst for the oxygen evolution reaction (OER). The results showed that the excitation of oxygen vacancies in CeO₂ accelerated the migration of oxygen species and enhanced the oxygen storage/release capacity of the as-prepared catalyst. Meanwhile, the size effect of CeO₂ particles enabled the timely discharge of gas bubbles from the reaction system and thus improved the OER kinetics. In addition, a large number of pyridine-N species were induced by CeO₂-doping and sequentially anchored in the carbon matrix. As a result, the Fe₂N active state was formed through the strengthened binding of Fe-N elements. Benefiting from the strong electronic interaction between Fe₂N and CeO₂ components, the optimal CeO₂-Fe₂N/NFC_-2 catalyst sample showed a good OER performance (E = 266 mV) and ORR electrocatalytic activity (E_1/2 = 0.87 V). The practical feasibility tests indicated that the Zn-air battery assembled by the CeO₂-Fe₂N/NFC_-2 catalyst exhibited a large energy density and an excellent long-term cycling stability.