Tailoring COFs for highly selective generation of singlet oxygen to boost antibiotic removal: Spatial regulation of PMS and photogenerated carriers

The high-selectivity generation of persulfate radicals (SO₅^·-) is key to achieving efficient and highly selective production of singlet oxygen (¹O₂). In this study, we designed a covalent organic framework (COF) catalyst with triazine rings as the core component, constructing a photo-assisted Fenton-like peroxymonosulfate (PMS) activation system (PI-COF/PMS/Light) for efficient antibiotic degradation. After 10 hours of continuous operation in a flow reactor, the system maintained over 90 % removal efficiency of LVX, demonstrating excellent long-term stability and anti-interference capability. Both theoretical calculations and experimental results indicate that the triazine rings in the structure functions dually as both photogenerated hole-trapping center and PMS specific adsorption site. This dual-functional integration drives the deprotonation process of PMS. Compared to the traditional electron activation pathway, this new hole-dominated activation mechanism effectively avoids the generation of radical-based pathways and significantly reduces the high energy consumption required for the indirect conversion of superoxide radicals to ¹O₂, thereby achieving highly selective (99.5 %) generation of ¹O₂. This work proposes a novel strategy for achieving high-selectivity ¹O₂ generation through precise molecular structural regulation of COFs, offering new insights for research on PMS photoactivation mechanisms and the development of efficient water treatment technologies.