Self-assembled composite heterojunction material PDIsm/BiOCOOH promotes photocatalytic degradation of levofloxacin

A broad-spectrum responsive organic-inorganic heterojunction was synthesized by in-situ self-assembled perylene diimide (PDIsm) through π-π stacking onto the surface of flower-like BiOCOOH. The PDIsm/BiOCOOH with different compositions exhibited enhanced photocatalytic degradation of levofloxacin under visible light irradiation. Among them, 10% PDIsm/BiOCOOH had the best photocatalytic activity, which was 4.6 and 14.1 times higher than pure PDIsm and BiOCOOH, respectively. The enhancement of photocatalytic activity was mainly attributed to the introduction of PDIsm which significantly improved the light absorption in almost the whole visible light range. Besides, the formed heterojunctions facilitate the separation and transfer of photogenerated charge carriers. In addition, after five cycles of degradation, the degradation rate of the PDIsm/BiOCOOH composite for levofloxacin hydrochloride remained above 75%, indicating its good photocatalytic activity and stability. Furthermore, free radical capture experiments and electron spin resonance experiments verify that •O2‾ and h+ were the active species generated in the photocatalytic process. Combining the experimental results of high-performance liquid chromatography-mass spectrometry, a possible photocatalytic reaction mechanism was proposed. This work provides a way to prepare an efficient organic-inorganic photocatalyst, which can potentially be utilized in environmental remediation under visible light.