Precise manipulation of iron spin states in single-atom catalytic membranes for singlet oxygen selective production.

Heterogeneous single-atom catalysts are attracting substantial attention for selectively generating singlet oxygen (¹O₂). However, precise manipulation of atom coordination structures remains challenging. Here, the fine coordination structure of iron single-atom carbon-nitride catalysts (Fe-CNs) was manipulated by precisely tuning the heating rate with 1 °C min^-1 difference. Multiple techniques in combination with density functional theory (DFT) calculations reveal that FeN₆ coordination sites with high Fe spin states promote the adsorption, electron transfer, and dissociation of peroxymonosulfate (PMS), resulting in nearly 100% selection of ¹O₂ generation. A lamellar single atom catalytic membrane is constructed, exhibiting high permeance, high degradation, high-salinity resistance and sustained operation stability. This work provides ideas for regulating spin states of the metal site to fabricate catalysts with selective ¹O₂ generation for membrane separation and environment catalysis applications.