Molecular engineering of perylene diimide polymers to enhance photocatalytic performance for efficient photodegradation of ofloxacin

The field of photocatalytic degradation has garnered considerable attention for perylene diimide (PDI), primarily because of their exceptional stability, distinctive optoelectronic properties, and outstanding charge transport efficiency. Nevertheless, the limited efficiency of photoinduced charge carrier utilization and poor recyclability pose challenges for real-world photocatalyst applications. We developed three polymers, m-PDI, p-PDI, and o-PDI, by reacting PDI with various benzene diamine compounds at different connection positions, aiming to improve the separation efficiency of photoinduced charge carriers. These unique connection sites resulted in variations in surface area, energy level distribution, and the migration and separation behaviors of photogenerated charge carriers within the polymers. Among the materials, m-PDI demonstrated the largest specific surface area along with the most deeply positioned valence band. Furthermore, its unique structure enabled stronger interactions with ofloxacin (OFL), facilitating more effective electron transfer from the OFL molecules to the catalyst compared to both p-PDI and o-PDI. Consequently, under light irradiation, m-PDI demonstrated outstanding photocatalytic efficiency, achieving a degradation rate constant of 0.07481 min(-1) within 60 min. This performance was approximately 4 times higher than that of p-PDI and 7 times greater than o-PDI. Additionally, the m-PDI composite showed excellent stability and resilience during recovery experiments and photocatalytic degradation tests in complex aquatic environments. Finally, LC-MS analysis was applied to predict degradation intermediates and pathways for OFL. This work opens up new possibilities for utilizing high-performance organic materials in the eco-friendly treatment of antibiotic-containing wastewater and provides valuable insights into their design principles.