Pre-coordination anchoring strategy for modulating the coordination structure of iron single atoms and ORR performance

Among numerous potential alternatives to platinum-based catalysts, single-atom Fe catalysts with a symmetrical planar tetra-coordinated structure anchored by nitrogen (FeN₄) have shown the most promising ORR activity. However, extensive research has shown that the highly symmetric planar structure of the FeN₄ site leads to symmetric electron distribution, which is detrimental to the adsorption and activation of oxygen intermediates, thereby hindering further improvement in ORR kinetics and performance. Herein, using the pre-coordination anchoring strategy, we prepared high-loading S, N-coordinated single-atom catalysts with an FeSN₃ structure (referred to as Fe SACs/SNC). Due to the optimized charge distribution of Fe active centers, Fe SACs/SNC exhibited outstanding alkaline ORR performance. In addition, Fe SACs/SNC assembled as air cathodes in liquid and solid zinc-air batteries showed stable cycling for over 900 h (2700 cycles) and 190 h (1140 cycles), respectively, while solid-state batteries also demonstrated good flexibility.