Dual confinement engineering in Ti-MOFs for stabilizing cobalt sites and regulating PMS activation toward singlet oxygen-mediated tetracycline degradation

The performance of peroxymonosulfate (PMS)-based advanced oxidation processes is often limited by inefficient reactive oxygen species (ROS) utilization and instability of active metal sites. Herein, a dual-confinement strategy is proposed by integrating spatial pore confinement and coordination confinement into Ti-based metal–organic frameworks (MOFs) to regulate PMS activation. Compared with Ti-BPDC, the pyridine-functionalized Ti-BPYDC framework provides Co N coordination sites, enabling stronger stabilization and electronic modulation of Co active centers. As a result, the Co-Ti-BPYDC/PMS system achieves enhanced tetracycline degradation (98.83% within 30 min), higher reaction kinetics (0.54 min −1 ), and improved mineralization (44.73%). Mechanistic studies reveal that the dual-confinement structure promotes interfacial electron transfer, stabilizes the Co 3+ /Co 2+ redox cycle, and favors a singlet oxygen ( 1 O 2 )-dominated non-radical pathway, while suppressing Co leaching. Consequently, the catalyst exhibits excellent stability and resistance to environmental interference. This work provides a general strategy for designing efficient and stable MOF-based catalysts for advanced oxidation processes.