Electron Pumping Overcomes Spin‐Crossover Barrier to Lock High‐Spin Single‐Atom Sites for Sustained Oxygen Reduction

ABSTRACT The oxygen reduction reaction (ORR) is kinetically limited by spin‐dependent adsorption of O 2 and intermediates at catalytic sites, yet the high‐spin configuration that promotes O 2 activation is inherently metastable and suffers from uncontrolled spin evolution. Herein, we propose an electron‐pumping strategy to overcome the spin‐forbidden energy barrier, which is achieved by the continuous and unidirectional electron extraction from Fe centers invariably to stabilize the active sites in high‐spin state. The sustained high‐spin state of Fe III (d 5 , S = 5/2) activates the e g orbitals to govern orbital hybridization and electronic coupling with intermediates, while simultaneously overcoming spin‐crossover barrier to continuously drive O 2 activation, thereby accelerating reaction onset and subsequent catalytic steps. Moreover, it reinforces O─O bond scission and eases *OH removal, synergistically enhancing the complete ORR dynamics. Consequently, the designed electrocatalyst delivers an outstanding half‐wave potential of 0.93 V with only 7 mV decay after 10 000 cycles. The assembled anion exchange membrane fuel cell achieves a peak power density of 966 mW cm −2 and retains 97% of its initial voltage after 50 h at 0.5 A cm −2 . This work establishes the electron‐pumping regulation as a paradigm for achieving intrinsic and sustained high‐spin stabilization, breaking the activity–stability trade‐off in oxygen electrocatalysis.