Lattice Confinement‐Steered Adaptive Crystal‐Field and Spin‐State Transition of Co Single‐Atom Sites for Robust Water Cleanup

Abstract Single‐atom catalysts (SACs) take a pivotal position in heterogeneous water purification, yet their deployment is restricted by poor yields, limited activity‐stability and high costs. Here, A simple and economical “frustrated Lewis pairs”‐assisted lattice confinement strategy is reported to construct tetrahedrally and octahedrally coordinated single‐atom Co sites in millimetric γ‐Al 2 O 3 (SCoA) at a kilogram level, achieving site‐specific spin state modulation of the lattice‐confined Co. The flexible lattice confinement leverages the tetrahedral and octahedral site interactions to form high‐spin‐dominated Co(II) centres. Synergistic adsorption of Co‐Al sites toward peroxymonosulfate induces an adaptive shift of high‐spin Co(II) from a tetrahedral to octahedral site, which provides an efficient spin channel for both proton/electron transport and conversion of high‐spin Co(II)/Co(III) into low‐spin Co(III) in the octahedral site, lowering the energy barrier of synchronously producing SO 4 •− and 1 O 2 . The unique mechanism sustains a high‐efficient removal of multiple pharmaceuticals/antibiotics and antibiotic resistance genes. Notably, the estimated cost of SCoA at ≈$53/kg is 2300–2600 times cheaper than that of commercial 3d ‐transition metal SACs. Thus, the proposed framework of lattice confinement‐augmented adaptive single‐atom catalysis establishes a low‐cost and versatile platform to address the issue of recalcitrant emerging contaminants, advancing clean water and water resilience against the global freshwater crisis.