Strategic Secondary Coordination Implantation Towards Efficient and Stable Fe─N─C Electrocatalysts for the Oxygen Reduction Reaction in PEMFCs.

While state-of-the-art Fe─N─C catalysts demonstrate platinum-comparable initial activity for the oxygen reduction reaction (ORR), their operational durability in proton exchange membrane fuel cells (PEMFCs) remains fundamentally limited by progressive destabilization of Fe─N bond under electrochemical cycling, resulting in irreversible metal leaching, catastrophic catalyst degradation and the so-called activity-stability trade-off. Herein, guided by first-principles screening, we demonstrate that the strategic implantation of transition metal ions with d-orbital characteristics analogous to the active site into the secondary coordination sphere, functioning as non-catalytic stabilizers, enables dynamic neutralization of reaction intermediates-induced electronic polarization, thereby achieving stabilization of metal─nitrogen bonds during the ORR cycle. As a proof-of-concept, the integration of isovalent Ru ions as electron-buffing site in the designed FeRu dual-atom catalyst not only achieves a high peak power density of 1.73 W cm with a current density of 58 mA cm at 0.9 V, but also exhibits exceptional durability, with a current decay rate of just 0.2 mA cm h and over 97% Fe retention after prolonged stability tests. This stands in stark contrast to Fe─N─C counterparts, which retain less than 11% of Fe sites under identical conditions.