Co/N Co-doped Micro-/Mesoporous Carbon Nanospheres as EfficientOxygen Reduction and Oxygen Evolution Reactions Electrocatalysts

Developing high efficiency and durability catalysts for the electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is fundamental to achieve the large-scale commercial application of fuel cells and metal-air batteries. Herein, a series of Co-N doped bi-functional hierarchical porous electrocatalysts were synthesized using polyvinyl pyrrolidone (PVP) as soft template to assist the Zn/Co bimetal Zeolitic Imidazolate Framework (BMZIF) to form micro-/mesoporous carbon nanospheres via a convenient one-step solution synthesis method, followed by pyrolysis to form carbon nanospheres catalysts. The as-prepared Co/N co-doped carbon exhibits outstanding performances in the ORR and OER due to the formed hierarchical pores architecture and the high surface area. The catalyst displays superior ORR performance with a high half-wave potential of 0.89 V, and a remarkable long-term stability in 0.1 M KOH. In addition, the electrocatalyst elicits a low voltage of 1.72 V under the current density of 10 mA cm(-2). Moreover, the zinc-air battery fabricated with P-CNCo-3 delivers a power density of 175.1 mW cm(-2), a high specific capacity of 791 mAh g(-1)and an energy density of 976 Wh kg(-1)at 20 mA cm(-2).