Asymmetric Co-O-La coordination achieves biocompatible and selective generation of high-valent cobalt-oxo species for boosting water purification.

Efficient activation of peroxymonosulfate (PMS) by cobalt-based catalysts is often limited by metal leaching, non-selective radical pathways, and associated biotoxicity, hindering their practical application in water purification. Here, cobalt atoms are embedded into the La2Ti2O7 perovskite lattice (Co-LTO), forming asymmetric Co-O-La coordination motifs that create a polarized electronic microenvironment. Airway organoid assays demonstrate that lattice confinement significantly suppresses cobalt associated biotoxicity compared to free cobalt ions. Experimental evidence and density functional theory reveal that the asymmetric Co-O-La coordination redistributes electron density at Co sites, lowers the energy barrier for PMS adsorption and activation, and promotes the selective generation of high-valent cobalt-oxo species via non-radical pathway. Consequently, Co-LTO achieves 99% sulfamethoxazole degradation within 4 min (k = 0.79 min-1), exhibiting 9.87- and 79-fold higher activity than Co3O4 (0.08 min-1) and pristine LTO (0.01 min-1), respectively. Continuous-flow experiments further confirm its structural stability and sustained catalytic performance. This work established lattice-confined asymmetric coordination as an effective strategy to modulate electronic structure, enabling efficient and biologically safer PMS activation for advanced water treatment.