Spatial Axial Oxygen Coordination of CoSA-N2O1/MXene Single-Atom Catalyst with Electron-Depleted Active Site for Selective 1O2 Generation

The electronic state modulation of catalytic active sites governs the oxidation/reduction activation pathway of peroxymonosulfate (PMS), however, directional singlet oxygen ( 1 O 2 ) generation via establishing electron-depleted active center remains challenging. Herein, we propose an innovative axial coordination strategy to engineer atomically dispersed Co-N x moieties on MXene substrates, creating a Co SA -N 2 O 1 /MXene catalyst with precisely modulated electron-depleted sites. The tailored electronic configuration redirects 2,4-dichlorophenol degradation from radical-dominated pathway (Co SA -N 4 counterpart without axial O modulation) to 1 O 2 -driven mechanism with 90.5% contribution, achieving up to 5.1-fold activity enhancement, even outperforming most state-of-the-art Fenton-like systems. The charge density redistribution and greater density of states near Fermi level accelerate PMS activation to selective generation of 1 O 2 . It also demonstrates exceptional environment robustness and high stability for treating real lake water. Our findings advance atomic-level insights into PMS activation and establish a novel paradigm of axial coordination engineering for designing next-generation single-atom catalysts.