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

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.