Researchers from Yonsei University's Department of Chemical and Biomolecular Engineering and Department of Materials Science and Engineering have collaborated to create a high-density dual iron (Fe) active site oxygen reduction catalyst for zinc-air batteries. This catalyst addresses the slow oxygen reduction reaction occurring at the air cathode, which has limited the practical performance of these next-generation energy storage devices. Traditional single-atom iron catalysts face challenges such as clustering of metal atoms and limited active structures, making it hard to achieve both high activity and stability.

To overcome these limitations, the team employed a systematic approach using a radical polymerization technique in water to environmentally synthesize polymers with chemical structures similar to metal-organic frameworks (MOFs). This new polymer was then coated onto the surface of MOFs using an interface control strategy that allowed metal ions on the MOF surface to bond with the polymer. The design facilitated a uniform and selective coating of the nitrogen-rich polymer layer on the dispersed MOF particles. Upon carbonization, these coated materials formed adjacently stabilized dual iron active sites within a carbon support.

The developed catalyst demonstrated remarkable performance; it achieved a half-wave potential of 0.91V, outperforming commercial Pt/C catalysts (0.86V) and confirming an ideal four-electron reduction pathway. In practical zinc-air battery applications, it recorded an open-circuit voltage of 1.46V and a maximum power density of 182 mW/cm2, along with maintaining stable charge and discharge performance for over 300 hours. This breakthrough represents a significant advancement in catalyst technology, potentially improving the efficiency of zinc-air batteries.