Engineered Co/Ni–N Bonds in Bimetallic Nanocomposites for Effective Oxygen Reduction Catalysts in Fuel Cells

The future advancement of anion exchange membrane fuel cells (AEMFCs) relies on the development of effective, durable, and economical oxygen reduction reaction (ORR) catalysts. This study introduces cost-effective, nonprecious metal electrocatalysts, specifically Co and Ni-based bimetallic nanocomposites (CoNi-bpy) synthesized with 4,4′-bipyridine as N-doped carbon supports, which demonstrate significant potential to enhance ORR performance in AEMFCs. Incorporating Ni and Co both individually and in combination into the carbon lattice forms Co/Ni–N bonds with optimized energy, facilitating M atom insertion and enhancing oxygen reduction activity by increasing the charge density difference and the positive charge cloud on the metal centers. This reduces the band gap and maps the distribution of charge clouds on the catalysts, facilitating O 2 adsorption, as supported by density functional theory calculations. CoNi-bpy catalyst demonstrated electrochemical stability, a half-wave potential ( E 1/2 ) of ∼0.76 V vs RHE, and a minimal voltage drop of ∼20 mV even after 20,000 potential cycles. AEMFCs was prepared using these low-cost catalyst deliver notable peak power densities, with the CoNi-bpy catalyst achieving ∼94 mW cm –2 at a current density of ∼290 mA cm –2 under ambient pressure and temperature. This nonprecious CoNi-bpy catalyst represents a significant step toward designing an affordable and highly efficient metal-based cathode electrocatalyst underscoring its effectiveness in ORR catalysis and its potential for widespread application.