A metal–organic framework derived FeCoZn co-doped nitrogen–carbon bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions

Abstract

It is of great significance to develop cost-effective and durable bifunctional electrocatalysts based on non-precious metals for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for the development of zinc–air batteries (ZABs). Among various candidates, nitrogen-coordinated transition metal composites embedded in carbon materials have emerged as promising alternatives. In this study, Fe²⁺ ions were incorporated into ZIF-8@ZIF-67 through a sequential coordination process. Subsequent pyrolysis under optimized conditions yielded a tri-metallic Fe, Co, and Zn co-doped nitrogen-enriched carbon composite (denoted as FeCoZn–NC-1.5-900). Electrochemical characterization revealed that FeCoZn–NC-1.5-900 demonstrates remarkable ORR and OER activities in alkaline media. The materials also exhibited exceptional durability and methanol resistance. As a proof-of-concept, FeCoZn–NC-1.5-900 was applied in a home-built ZAB, which enabled stable charge–discharge cycling. This methodology establishes a viable pathway for designing noble metal-free electrocatalytic systems through rational multi-metal coordination and thermal modulation.