Asymmetric Coordination Modulating Co Spin State for Peroxymonosulfate Activation to Accelerate ¹ O ₂ Generation

Abstract Singlet oxygen ( ¹ O ₂ ) has received extensive attention for the selective degradation of emerging contaminants. However, how to efficiently generate ¹ O ₂ by modulating the asymmetric structure and electron spin state of catalyst remains a challenge. Herein, an asymmetric Fe─S─Co structured catalyst (Co‐Fe ₃ S ₄ ) is designed by in situ substitution of Fe ^III _Td strategy. The strong interaction in the asymmetric structure induces a low‐spin state ( e : ↑↓ , ↑↓ , t ₂ : ↑↓ , _, _) at d‐orbital of Co sites, shifting the d‐band center closer to the Fermi level and elevating the antibonding states, which is beneficial for the adsorption of peroxymonosulfate (PMS). The catalyst accelerates ¹ O ₂ generation by PMS activation, achieving 100% removal of acetaminophen in pharmaceutical wastewater in 8 min with a high K‐value of 112 min⁻¹ M⁻¹. Experiments and DFT calculations reveal that the spin state of the generated *O ₂ (from the S─O bond cleavage in HSO ₅ ⁻ ) is reduced by electron reversal ( ↓ to ↑ ) or pairing ( ↑ , ↑ to ↑↓ , _) in the 2p (2p _x and 2p _y ) orbitals of the O─O anti‐π bond (π*), resulting in the ¹ O ₂ generation. This work presents an approach for regulating the spin state using an asymmetric structure and offers a broader perspective on the generation mechanism of ¹ O ₂ .