Piezo-photocatalytic synergy in COF/PVDF-HFP porous films for efficient dye degradation and broad-spectrum antibacterial

Developing flexible, metal-free membranes for efficient piezo-photocatalytic environmental remediation remains a critical challenge. Herein, an all-organic, hierarchical porous COF/PVDF-HFP composite film was fabricated via a phase inversion method. Driven by strong interfacial hydrogen bonding, the COF nanoparticles (with an optimal loading of 5 wt%) served as efficient nucleating agents, significantly enhancing the electroactive β-phase content of the PVDF-HFP matrix and boosting its piezoelectric response. Under simultaneous light and ultrasonic excitation, the optimized composite achieved a remarkable Rhodamine B degradation efficiency of 97.73% within 180 min, exhibiting a kinetic rate 2.3 times higher than that of pristine PVDF-HFP. Furthermore, it demonstrated robust broad-spectrum antibacterial efficacy (>99% sterilization) against both E. coli and S. aureus . Crucially, by integrating density functional theory (DFT) calculations with absolute band alignments (UPS) and dynamic in-situ XPS tracing, we definitively unveiled an internal electric field-driven S-scheme heterojunction mechanism. This S-scheme pathway dynamically steers charge recombination, successfully retaining highly reductive photogenerated electrons on the COF to thermodynamically favor the dominant generation of superoxide radicals (·O 2 − ) and a remarkable yield of H 2 O 2 (937.6 µM). Exhibiting exceptional structural stability over multiple cycles, this entirely metal-free composite offers a robust, sustainable paradigm for engineering high-performance piezo-photocatalytic interfaces for water purification and hygiene protection.