Cu-Modified Zirconium Metal Organic Framework DUT-67 Schottky Heterojunction for Full-spectrum Antibiotic Degradation: Mechanistic Insights, Degradation Pathways, and Toxicity Assessment

Abstract Photocatalysis is an efficient approach for antibiotic remediation, but rapid carrier recombination remains a key challenge. Here, we construct an oxygen-vacancy rich Cu/DUT-67 Schottky junction photocatalyst for antibiotics degradation. Surface oxygen vacancies provide abundant adsorption sites, while the interfacial built-in electric field drives directional electron migration, suppressing carrier recombination. The optimized Cu/DUT-67-2 achieves tetracycline and oxytetracycline removal efficiencies of 84.05% within 150 min and 83.87% within 120 min, respectively, substantially outperforming pristine Dresden University of Technology-67 (DUT-67). Mechanistic studies show that h+ and ·O2– synergistically dominate the degradation process. Cu/DUT-67-2 also exhibits excellent stability, and gel microspheres containing the catalyst enable continuous antibiotic removal under illumination. Molecular reactivity and high-performance liquid chromatography-mass spectrometry (HPLC-MS) analyses elucidate the reactive sites, degradation intermediates, and degradation pathways of the antibiotics. Toxicological evaluation and bean sprout germination tests confirm effective degradation with significantly reduced ecological toxicity. Meanwhile, the bacteriostatic rates of Cu/DUT-67-2 against E. coli and S. aureus reach 98.82% and 98.68%, respectively. This work integrates defect regulation with interface engineering for synergistic adsorption and catalysis, offering a feasible strategy for antibiotic pollution remediation.