Phosphorus-induced single-atom iron coordination symmetry disruption for superior catalytic ozonation

Heterogeneous catalytic ozonation (HCO) triggered by single-atom catalysts (SACs) is a promising technology for advanced wastewater purification. However, high symmetry of conventional metal-N₄ structures limits catalytic performance. Herein, we construct an asymmetrically coordinated Fe-N₃P₁ moiety in Fe-NPC catalyst, where the short-range coordination effect of P significantly enhances HCO. The Fe-NPC/O₃ achieves 100% removal of model pollutant p-hydroxybenzoic acid, with a kinetic constant of 0.123 min^-1, and also demonstrates excellent advanced treatment for coal chemical wastewater. The degradation of contaminants is attributed to ozone and nonradical singlet oxygen. Theoretical calculations reveal that the central Fe atom in Fe-N₃P₁ is the main site for HCO, and the introduction of P primarily modulates the electronic structure of Fe atom by altering its coordination environment. This work provides a short-range coordination strategy for regulating the electronic properties of isolated metal centers and sheds light on the HCO pathways with asymmetrically coordinated SACs.