Synergistic effect between atomically dispersed Fe and Co metal sites for enhanced oxygen reduction reaction

Rational design of isolated metal atom doped carbon catalysts is essential for revealing the essence of high activity for the oxygen reduction reaction (ORR), which can promote the development of robust catalysts for clean energy conversion devices. Herein, we report a simple one-step strategy to prepare Fe and Co atomically supported on N-doped nanocarbon (FeCo-IA/NC) from metal-organic frameworks with excellent ORR activity. The isolated Fe-N₄ and Co-N₄ sites are characterized by atomic-resolution aberration-corrected scanning transmission electron microscopy and X-ray absorption fine structure spectroscopy. The electrochemical results and density functional theory calculations indicate that the synergetic effect between Fe-N₄ and Co-N₄ accounts for the enhanced ORR activity. Benefiting from the large BET surface area, microporous feature, and high content (85%) of pyridinic and graphitic N, the well-designed catalyst exhibits better ORR activity (half-wave potential of 0.88 V) and Zn-air battery performances (higher open circuit potential and power density) than commercial Pt/C. This work may lay a foundation for further exploring efficient non-precious metal-based catalysts for the ORR and developing clean energy conversion devices.