Silsesquioxane-Based Hybrid Semiconductor Polymers for Efficient Antibiotic Photodegradation and Detection Simultaneously

Recently, photocatalysis technology has become a promising wastewater treatment technology due to its advantages of green, high efficiency, and low cost. In this study, two silsesquioxane-based fluorescent hybrid porous polymers with semiconducting properties, PCS–PSP and PCS–PSSP, were synthesized by the Friedel–Crafts reaction of octavinylsilsesquioxane with 4,4′-thiene-2,5-diyldibenzonitrile (PSP) and 4,4′-(2,2′-bithiophene-5,5′-diyl)dibenzonitrile (PSSP). The study focused on their physicochemical characterization and photocatalytic activity. Compared with PCS–PSSP, PCS–PSP showed higher thermal decomposition temperature (T_5% = 385 °C), larger specific surface area (1001 m² g^–1), greater pore volume (0.75 cm³ g^–1), more substantial light absorption capacity (250–561 nm), and smaller optical band gap (E_g = 2.21 eV). Their photocatalytic ability was carried out to degrade tetracycline (TH) under visible light, and PCS–PSP exhibited a superior performance with 51% of TH adsorption in the dark and 84% removal efficiency after 1 h of light irradiation. Meanwhile, it also has excellent stability and recyclability. Free-radical trapping experiments and electron spin resonance tests revealed that superoxide radicals (^•O₂^–) played a significant role in the photocatalytic degradation process. Surprisingly, PCS–PSP also can be used as a probe for TH detection with high sensitivity and selectivity. This work provides a strategy for simultaneous antibiotic photodegradation and detection in environmental applications.