Hierarchically Porous Co and N‐Codoped Carbon Hollow Structure Derived from PS@ZIF‐67 as an Electrocatalyst for Oxygen Reduction

Abstract The development of low‐cost, highly efficient, and durable electrocatalysts for oxygen reduction reaction (ORR) is vital to commercialization of a new generation of rechargeable metal‐air batteries and fuel cells. Here we report a facile, efficient, template‐assisted strategy for fabrication of hierarchically porous Co, N‐codoped carbon hollow structures as ORR eletrocatalysts. The unique architecture of the catalyst was constructed through in situ growth of Co‐based zeolitic imidazolate framework (ZIF‐67) on the surface of carboxylated polystyrene (PS) nanosphere and pyrolysis for removal of PS and carbonization of ZIF‐67. The resulting catalyst exhibited outstanding ORR activity in both alkaline and acidic electrolyte solution, comparable to that of a commercial Pt/C catalyst, and better than those reported for most Co, N‐codoped carbon catalysts. Such superior performance is attributed to the unique features of the catalyst: large specific surface area, openly exposed active sites, high content of the pyridinic‐N and graphitic‐N active sites, and fast transfer of electrons and ions. Moreover, the catalyst also displayed much better tolerance to methanol and durability than the commercial Pt/C catalyst, ascribed to strong coupling of active sites and highly graphitic carbon sheets. Further, the simple, effective and low‐cost synthesis strategy for creation of hierarchically porous electrodes is applicable to fabrication of other energy storage and conversion devices as well.