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

Abstract

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.