Interfacial engineering of Mg3O(CO3)2-bound cobalt nanosheets via one-pot synthesis for PMS-driven water decontamination.

Antibiotic contamination threatens global water security and public health. Peroxymonosulfate (PMS) activation provides an environmentally sustainable approach for water remediation, but conventional cobalt-based catalysts face low atomic utilization and metal leaching issues. Herein, we developed a novel a CoMg/HMTA composite through a one-step hydrothermal method using hexamethylenetetramine (HMTA) and magnesium salts enable the dispersion of cobalt nanosheets on Mg₃O(CO₃)₂substrates. The alkaline carrier Mg₃O(CO₃)₂not only stabilizes Co sites but also minimizes Co leaching (0.18 mg l^-1). The optimized system achieved 99.6% metronidazole (MNZ) degradation in 30 min and maintained >99% efficiency over six cycles, demonstrating superior catalytic performance. This strategy was generalized to Cu and Ni systems, confirming the universal stabilizing role of Mg-based carriers. Mechanistic studies using EPR spectroscopy and quenching tests revealed a multi-level degradation mechanism involving radicals (SO₄^•-, O₂^•-) and non-radicals (¹O₂), showing robust performance in various water matrices. This work provides a scalable platform for designing stable persulfate activators against emerging contaminants.