Facet Strain Strategy of Atomically Dispersed FeNC Catalyst for Efficient Oxygen Electrocatalysis

Abstract Increasing the portion of highly active metal centers in atomically dispersed MNC catalysts is significant for the overall oxygen reduction reaction (ORR) performance. A “facet strain strategy” is designed by using a trans‐layer compressive strain of the {110} facet of FeCo nanoparticles encapsulated in graphitic FeNC layers to further activate the primitive FeN₄ catalytic centers on the graphitic sub‐layer that are omitted in commonly direct access activation strategies. Using X‐ray absorption near‐edge spectroscopy and extended X‐ray absorption fine structure, the highly active FeN₄ type is detected with compressed FeN bonds. Density functional theory calculation discloses that, in virtue of lattice mismatch, FeCo {110} facets transmit a trans‐layer compressive strain to reconstruct the FeN₄ sites on surrounding graphitic sub‐layers to optimize the Fe‐OH* adsorption energy in the rate‐determining step. The redesigned catalyst exhibits enhanced ORR activity, outperforming the primitive FeNC and commercial Pt/C benchmarks. This study will enrich insights toward developing MN₄ and nanoparticle composite electrocatalysts.