Coupling nano-Fe3O4 with oxygen vacancies on a hypercrosslinked iron porphyrin-coated ZIF-8 as a high-efficiency oxygen reduction reaction electrocatalyst

作者：Song, Kunpeng^*; Dong, Wen; Tang, Cheng; Zou, Zhijuan; Wu, Yundang^*

来源：Applied Catalysis A: General , 2022, 642: 118712.

DOI：10.1016/j.apcata.2022.118712

• Fe3O4 nanoparticles
• Hypercrosslined iron porphyrins
• ZIF-8
• Oxygen vacancies
• Oxygen reduction reaction

In this study, a novel and highly efficient ORR catalyst is designed via the pyrolysis of zeolitic imidazole framework-8 (ZIF-8) under the protection of hypercrosslinked iron porphyrins. Fe3O4 nanoparticles with oxygen vacancies are formed in situ and promoting catalytic efficiency. Benefiting from the synergistic effect among the Fe3O4 and ZIF-8 skeleton, the hybrid catalyst exhibits excellent ORR activity even surpassing commercial Pt/C. The pyrolyzation temperature is studied in detail and determined to be a crucial parameter for ORR performance. Nano-Fe3O4, which has high catalytic efficiency, is formed in situ at 800 degrees C. Amorphous iron is formed at 600 degrees C and 700 degrees C, and zero-valent iron is formed at 900 degrees C. The content of oxygen vacancies, Fe-N, and graphite-N, which are beneficial to the ORR reaction, are all reached to a maximum at 800 degrees C. This study provides a new approach to design highly active Fe3O4-based electrocatalytic materials.