N-doped carbon-supported Co-Nx nanoclusters for efficient oxygen reduction in direct ammonia borane fuel cells

Developing efficient, cost-effective, and durable oxygen reduction reaction (ORR) catalysts to accelerate the sluggish kinetics, is crucial for emerging alkaline fuel cell technologies such as direct ammonia borane fuel cells (DABFCs). Herein, a bimetallic metal–organic framework (MOF)-derived Co-N x /NC catalyst with highly dispersed Co-N x nanoclusters embedded in an N-doped carbon framework is synthesized for enhanced ORR performance. The Co-N x /NC catalyst displays a half-wave potential of 0.86 V vs. RHE in 0.1 M KOH and excellent stability with 99.2% current retention at 0.67 V vs. RHE for 20000 s. When applied in a DABFC single cell, it achieves a peak power density of 33 mW cm −2 at 298 K under low fuel and electrolyte concentrations (1.0 M KOH + 0.1 M AB). Structural characterization and electrochemical analyses suggest that the enhanced ORR activity and stability are associated with highly dispersed Co-N x nanoclusters and pyridinic-N species. This work highlights a bimetallic MOF precursor strategy for developing high-performance ORR catalysts for alkaline fuel cells.