Honeycomb structure + asymmetric single-atom sites: new catalyst dramatically boosts oxygen reduction reaction efficiency

Fe-N₄ is a typical active site in Fe-N/C catalysts with maximum atomic utilization and a well-defined structure. However, its high symmetry limits further electronic structure optimization and performance enhancement.

Here, we construct an asymmetric Fe single-atom site by an axial Cl coordination, breaking the Fe-N₄ planar symmetry. This increases electronic inhomogeneity, weakens the binding strength of Fe to oxygen reaction intermediates, and enhances ORR performance.

This work also proposes a zinc-assisted method to create a unique honeycomb-like porous structure to expose more active sites and enhance mass transport. Through synergistic regulation, it shows excellent ORR performance (E_1/2 = 0.81 V in acid, 0.91 V in base). This offers a new strategy for making micro-nano porous single-atom catalysts and provides new insights into ORR mechanisms, advancing energy devices.

The work titled “Honeycomb-like single-atom catalysts with FeN₃Cl sites for high-performance oxygen reduction”, was published on Advanced Powder Materials (Available online 30 April 2025).