Gd‐Mediated Spin‐State Modulation of Co Sites Enhances Oxygen Electrocatalysis in Zn‐Air Battery

ABSTRACT Co‐based catalysts are promising alternatives to precious‐metal catalysts towards oxygen reduction reaction (ORR), yet the limited electronic flexibility of Co sites constrains the adsorption and conversion of oxygen‐containing intermediates. Herein, we propose a Gd‐mediated spin‐state modulation strategy to enhance electrocatalytic ORR performance of Co sites. The incorporation of Gd into Co sites is realized by zeolitic imidazolate framework‐8, forming a Gd‐modified Co─N─C catalyst (GdCo/NC). The resulting GdCo/NC exhibits a higher half‐wave potential of 0.861 V in alkaline media than that of Co/NC (0.824 V) and commercial Pt/C (0.843 V). The rechargeable Zn‐air battery assembled with GdCo/NC demonstrates great practical performance, delivering a high peak power density of 170.8 mW cm −2 and a large specific capacity of 733 mAh g −1 , outperforming that of Pt/C + RuO 2 benchmark. Theoretical calculations reveal that Gd incorporation modulates the local electronic structure of Co centers by inducing pronounced spin splitting and orbital‐selective spin polarization, which shifts the dominant spin polarization from d z2 orbital to d yz orbital and lifts the degeneracy of d xz and d yz orbitals. Such spin‐dependent electronic reconstruction optimizes the adsorption of oxygen‐containing intermediates and shifts the rate‐determining step from *O protonation to *OH desorption, thus leading to excellent ORR performance.