Zn-MOF-74 Derived N-Doped Mesoporous Carbon as pH-Universal Electrocatalyst for Oxygen Reduction Reaction

It is of increasing importance to explore new low-cost and high-activity electrocatalysts for oxygen reduction reaction (ORR), which have had a substantial impact across a diverse range of energy conversion system, including various fuel cell and metal-air batteries. Although engineering carbon nanostructures have been widely explored as a candidate class of Pt-based ORR electrocatalysts owing to their proved high activity, outstanding stability, and ease of use, there still remains a daunting challenge to develop high activity metal-free electrocatalysts in pH-universal electrolyte system. Here, a reliable and controllable route amenable to prepare nitrogen-doped porous carbon (NPC) with high yields and exceptional quality is described. The as-prepared NPC shows advantages of high activity, high durability, and methanol-tolerant as an efficient pH-universal electrocatalyst for ORR, showing comparable or even better activity as compared with the commercial Pt/C catalysts not only in alkaline media but also in acidic and neutral electrolyte. Systematic electrochemical studies, combining with density functional theory calculation, demonstrate the unique nitrogen-doping species and favorable pores in the as-designed NPC synergistically contribute to the significantly improved catalytic activity in pH-universal medium. The present work potentially presents an important breakthrough in developing ORR electrocatalysts for various fuel cells.