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

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-j=10 = 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.