Non-radical reaction route for organic pollutants degradation in heterogeneous advanced oxidation processes (AOPs) has drawn intensive attention due to its high anti-interference performance in water treatment. However, effective catalysts are still needed to regulate the produced reactive species and reaction route. In this study, a defective cobalt-based metal-organic frameworks (MOF-LC) was synthesized via a controlled ligand-deficient strategy, which showed exceptional peroxymonosulfate (PMS) activation performance for fluorouracil (FLU) degradation structural and spectroscopic analyses confirmed the engineered Co–O coordination defects, leading to lowered crystal field splitting energy while enhanced spin coupling due to partially vacant Co 3d orbitals, then greatly promoting electron transfer for PMS activation. Ligand defect can effectively coordinate with PMS molecules, leading to charge delocalization for promoted PMS activation. Owing to delocalized orbitals at defect sites, [O≡CoII]–HSO5− rapidly transforms into <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$[{{\rm{O}} \equiv {\rm{C}}{{\rm{o}}^{{\rm{II}}}}}] - {\rm{SO}}_{\dot 5}^{-} $</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mo stretchy="false">[</mo> <mrow> <mrow> <mrow> <mi mathvariant="normal">O</mi> </mrow> </mrow> <mo>≡</mo> <mrow> <mrow> <mi mathvariant="normal">C</mi> </mrow> </mrow> <mrow> <msup> <mrow> <mrow> <mi mathvariant="normal">o</mi> </mrow> </mrow> <mrow> <mrow> <mrow> <mi mathvariant="normal">I</mi> <mi mathvariant="normal">I</mi> </mrow> </mrow> </mrow> </msup> </mrow> </mrow> <mo stretchy="false">]</mo> <mo>−</mo> <msubsup> <mrow> <mrow> <mi mathvariant="normal">S</mi> <mi mathvariant="normal">O</mi> </mrow> </mrow> <mrow> <mrow> <mover> <mn>5</mn> <mo>˙</mo> </mover> </mrow> </mrow> <mrow> <mo>−</mo> </mrow> </msubsup> </math></EquationSource> </InlineEquation>, subsequently driving two-step single electron transfer for selective generation of singlet oxygen (1O2). Compared with the conventional Co-MOF-74, the optimized MOF-LC1 exhibited a 17.8-fold higher FLU degradation rate, achieving 93.0% FLU removal within 5 min. In addition, the defective structure facilitated single-electron transfer without Co redox cycling, ensuring high stability and high pH resistance. Mass analysis and DFT calculation on Fukui index further identified defluorination and C-N cleavage as dominant degradation pathways of FLU, with reduced toxicity of byproducts. This work provides a defect-engineering strategy for designing efficient MOF catalysts and methods of selectively generating 1O2 in advanced oxidation processes.

Defective cobalt-metal-organic frameworks induced charge delocalization for efficient peroxymonosulfate activation and singlet oxygen dominated fluorouracil degradation in water

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发表日期：

2026年4月21日

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Yue Liu,
Jingjing Yao,
Zhenyu He,
Tianwei Qian,
Xiaona Liu,
Fan Li,
Shimei Yin,
Wenjun Li,
Long Chen

摘要

Non-radical reaction route for organic pollutants degradation in heterogeneous advanced oxidation processes (AOPs) has drawn intensive attention due to its high anti-interference performance in water treatment. However, effective catalysts are still needed to regulate the produced reactive species and reaction route. In this study, a defective cobalt-based metal-organic frameworks (MOF-LC) was synthesized via a controlled ligand-deficient strategy, which showed exceptional peroxymonosulfate (PMS) activation performance for fluorouracil (FLU) degradation structural and spectroscopic analyses confirmed the engineered Co–O coordination defects, leading to lowered crystal field splitting energy while enhanced spin coupling due to partially vacant Co 3d orbitals, then greatly promoting electron transfer for PMS activation. Ligand defect can effectively coordinate with PMS molecules, leading to charge delocalization for promoted PMS activation. Owing to delocalized orbitals at defect sites, [O≡Co^II]–HSO₅⁻ rapidly transforms into $[{{\rm{O}} \equiv {\rm{C}}{{\rm{o}}^{{\rm{II}}}}}] - {\rm{SO}}_{\dot 5}^{-} $ $[O \equiv C o^{I I}] - {S O}_{\dot{5}}^{-}$ , subsequently driving two-step single electron transfer for selective generation of singlet oxygen (¹O₂). Compared with the conventional Co-MOF-74, the optimized MOF-LC1 exhibited a 17.8-fold higher FLU degradation rate, achieving 93.0% FLU removal within 5 min. In addition, the defective structure facilitated single-electron transfer without Co redox cycling, ensuring high stability and high pH resistance. Mass analysis and DFT calculation on Fukui index further identified defluorination and C-N cleavage as dominant degradation pathways of FLU, with reduced toxicity of byproducts. This work provides a defect-engineering strategy for designing efficient MOF catalysts and methods of selectively generating ¹O₂ in advanced oxidation processes.