Spontaneous ferromagnetic Fe–La geminal atoms with spin and coordination modulation for acidic oxygen reduction

Synergistic spin-state and local coordination engineering offers a promising strategy for enhancing the acidic oxygen reduction reaction performance of Fe–N–C electrocatalysts, yet the precise control and stabilization of active sites remain challenging. Here we report a Fe–La geminal-atom electrocatalyst (Fe1-La1/NC) with spontaneous ferromagnetic spin ordering for acidic oxygen reduction reaction. The catalyst achieves a half-wave potential of 0.92 V and a turnover frequency of 17.3e-site−1s−1, compared with commercial Pt/C (0.87 V, 9.9e-site−1s−1). A proton exchange membrane fuel cell equipped with Fe1-La1/NC cathode delivers a high current density of 56 mA cm−2 at 0.9ViR-free under H2-O2 condition, while maintaining stable operation for 100 h at 0.67 V with 86% performance retention. Operando studies and theoretical simulations reveal that La incorporation promotes a spin-polarized high-spin Fe 3 d configuration and room-temperature ferromagnetic ordering, while also regulating the local coordination/electronic structure and oxygen-intermediate adsorption. Moreover, La enables dynamic self-adaptive stabilization of Fe sites, which mitigates the conventional activity–stability trade-off. This finding provides an avenue to rationally design efficient and selective electrocatalysts. Developing robust Fe–N–C catalysts that unite activity and durability remains challenging for acidic oxygen reduction. Here, the authors report spontaneous ferromagnetic Fe–La geminal atoms that create high-spin Fe sites and a spin pinning effect for fuel-cell catalysis.