Phthalocyanine-based covalent organic frameworks for visible-light-driven treatment of tetracycline pollution and tetracycline-induced Microcystis aeruginosa proliferation

The co-occurrence of harmful algal blooms and antibiotic residues poses a critical challenge for water pollution control, requiring photocatalysts with both high reactivity and environmental adaptability. Herein, two cobalt phthalocyanine-based covalent organic frameworks (PcPy-COF and PcPyCl-COF) were constructed and systematically evaluated for visible-light-driven inhibition of Microcystis aeruginosa under tetracycline (TC, 500 μg/L) stress. Both COFs exhibited robust structural order, strong metal–ligand coordination, and catalytic stability, achieving effective algal inactivation within 72 h. PcPy-COF showed superior performance at a low dosage (5 mg/L), with consistent efficacy across five natural water matrices. Mechanistic investigations revealed that photocatalytic suppression was driven by reactive oxygen species (ROS)-induced oxidative stress, as evidenced by pigment degradation, membrane disruption, and EPR detection of ·OH and O 2 · - . DFT calculations indicated enhanced charge separation in PcPy-COF (CT: 90.7%), a lower exciton binding energy (0.97 eV), and more favorable O 2 reduction thermodynamics. Combined Gibbs free energy and density of states analyses further supported its enhanced electron transfer and oxygen activation capabilities. This work provides valuable guidance for the rational design of COF-based photocatalysts for integrated remediation of eutrophication and antibiotic pollution.