Insights Into the Effect of Nickel Doping on ZIF-Derived Oxygen Reduction Catalysts for Zinc−Air Batteries

Abstract

The advancement of cost-effective, efficient, and durable catalysts to replace high cost Pt-based electrocatalysts are of recent interest, especially to enhance the sluggish oxygen reduction reaction (ORR) in fuel cells and metal−air batteries. Herein, we report self-assembled Co−Ni based nitrogen doped carbon structures (Co−Ni/NC) derived from zeolitic imidazolate frameworks as a highly efficient and durable ORR catalyst for rechargeable zinc−air batteries (ZAB). An effective three-phase boundary is recognised with a well-organized interconnected porous carbon framework of the Co−Ni/NC catalyst. The developed catalyst exhibited much improved onset and half-wave potentials (0.93 V and 0.86 V vs. RHE, respectively) in alkaline electrolyte, especially in the limiting current region, which was credited to the porous structure. Furthermore, excellent durability was found for the catalyst operated using continuous potential cycles for 5,000 times and chronoamperometric measurements for 50 h. Finally, the optimised Co−Ni/NC catalyst was successfully utilised as a cathode catalyst and delivered substantial power density in ZAB configuration under ambient operating conditions. Substantial battery durability was also observed over 1000 h by periodically replacing the anodic zinc electrode. Hence, the present investigation offers the prospect of the development of new non-precious, highly active, and durable oxygen reduction catalysts for zinc air battery applications.