Engineering Co–N _x Active Centers via Zinc‐Mediated Coordination in Hierarchically Porous Carbon for Enhanced Oxygen Reduction Reaction

Abstract Oxygen reduction reaction electrocatalysts are crucial for the advancement of high‐efficiency fuel cells and metal‐air batteries. However, the development of cost‐effective catalysts with high activities and durabilities remains challenging. Here, a cost‐effective method is presented for synthesising Co‐N x doped hierarchically porous carbon (ZC‐N/C) from a conducting polymer, delivering excellent ORR activity and stability. The high performance is attributed to the dense Co‐N x active sites formed via Zn ion incorporation, which increases the surface area and prevents cobalt oxide/sulfide formation, stabilising the Co 2+ /Co 3+ states. The synergistic effect of Zn, Co, and the N‐doped carbon matrix modifies the electronic structure, enhancing the reaction site density and boosting the ORR activity. ZC‐N/C exhibits ORR onset and half‐wave potentials that are comparable to those of commercial Pt/C under alkaline conditions. The doped Co/Zn‐N x moieties provide excellent stability, with a ΔE 1/2 of only 16 mV after 10 000 cycles (0.6 – 1 V vs RHE). As a cathode in an anion membrane fuel cell, ZC‐N/C achieves a peak power density of 215 mW cm −2 , similar to Pt/C. In a zinc‐air cell, it delivers 136 mW cm −2 power density and 780 mAh g Zn −1 capacity at 5 mA cm −2 demonstrating strong potential as a low‐cost ORR electrocatalyst.