MOF@COF-derived hierarchical carbon frameworks via phosphorization treatment: Synthesis and bifunctional oxygen catalytic mechanisms

Developing cost-effective bifunctional oxygen catalysts with robust activity and stability remains a core challenge for rechargeable zinc-air batteries (ZABs), primarily hindered by the slow kinetics of oxygen reduction/evolution reactions (ORR/OER). Herein, we report a Fe/Co-based composite catalyst, P-Fe-ZIF67@PI-COF-T (T represents calcination temperature), which is constructed by using a polyimide-based covalent organic framework as a support, followed by phosphorization and high-temperature pyrolysis of ZIF67 (zeolitic imidazolate framework67). Electrochemical measurements demonstrate outstanding bifunctional performance: an ORR half-wave potential (E 1/2 ) of 0.81 V, an OER overpotential of 250 mV at 10 mA cm −2 , and a ΔE of 0.67 V. The corresponding ZABs exhibit a high peak power density of 142.8 mW cm −2 and long-term durability for 300 h. Systematic analysis attributes the excellent performance to the synergistic effects of N/P co-doping induced defects, and the graphitized carbon layer. This study provides a rational design principle for advanced non-noble metal catalysts.