Molecular engineering and channel structure modulation for single-atom iron-embedded high-porosity carbon fibers with enhanced oxygen reduction reaction and zinc-air battery performance.

Iron-based electrocatalysts, owing to their unique electronic structures and abundant resource availability, exhibit significant potential as alternatives to precious metal materials in the oxygen reduction reaction (ORR) catalytic systems of zinc-air batteries. In particular, FeN single-atom catalysts (SACs), with their atomically dispersed active sites and well-defined FeN coordination structure, have further broken through the performance bottlenecks of traditional catalysts. However, the precise and controllable synthesis of the coordination configuration of FeN SACs still faces multiple scientific challenges. Meanwhile, traditional Fe-N-C catalysts are also limited by restricted mass transfer and low utilization efficiency of active sites due to the dense carbon matrix. In this study, we innovatively utilized natural chlorophyllin iron complex (Fe-Chl) and adopted an electrospinning strategy that integrates molecular engineering with the modulation of oriented hollow-channel porous structure. This approach successfully enabled the construction of a single-atom iron-anchored high-porosity carbon fiber catalyst (FeSA@HPCF). This strategy achieves precise reproduction of the FeN active center structure and enables multi-level modulation of the pore architecture. Owing to unique structural features, the FeSA@HPCF catalyst demonstrates superior ORR activity (E = 0.87 V) and excellent four-electron selectivity. This study, via precise molecular-level regulation, not only enabled the customizable construction of the microstructure of FeN catalysts but also addressed the inherent densification limitation in traditional iron-based catalysts supported on carbon materials. Furthermore, it established a versatile and adaptable design platform for enhancing the performance of ORR.