MOF‐Based Metal‐Doping‐Induced Synthesis of Hierarchical Porous CuN/C Oxygen Reduction Electrocatalysts for Zn–Air Batteries

A transition‐metal–nitrogen/carbon (TM–N/C, TM = Fe, Co, Ni, etc.) system is a popular, nonprecious‐metal oxygen reduction reaction (ORR) electrocatalyst for fuel cell and metal–air battery applications. However, there remains a lack of comprehensive understanding about the ORR electrocatalytic mechanism on these catalysts, especially the roles of different forms of metal species on electrocatalytic performance. Here, a novel CuN/C ORR electrocatalyst with a hybrid Cu coordination site is successfully fabricated with a simple but efficient metal–organic‐framework‐based, metal‐doping‐induced synthesis strategy. By directly pyrolyzing Cu‐doped zeolitic‐imidazolate‐framework‐8 polyhedrons, the obtained CuN/C catalyst can achieve a high specific surface area of 1182 m2 g−1 with a refined hierarchical porous structure and a high surface N content of 11.05 at%. Moreover, regulating the Cu loading can efficiently tune the states of Cu(II) and Cu0, resulting in the successful construction of a highly active hybrid coordination site of NCu(II)Cu0 in derived CuN/C catalysts. As a result, the optimized 25% CuN/C catalyst possesses a high ORR activity and stability in 0.1 m KOH solution, as well as excellent performance and stability in a Zn–air battery. A novel CuN/C oxygen reduction reaction electrocatalyst with a highly active hybrid Cu coordination site of NCu(II)Cu0 and hierarchical porous structure is successfully constructed with a simple but efficient metal–organic‐framework‐based metal‐doping‐induced synthesis strategy. The optimized 25% CuN/C catalyst shows comparable electrocatalytic activity but superior durability in 0.1 m KOH solution and a Zn–air battery, compared with 30 wt% Pt/C.