Dual-defects modified ultrathin 2D/2D TiO2/g-C3N4 heterojunction for efficient removal of levofloxacin: Performance, degradation pathway, and mechanism

Developing high-efficiency photocatalysts to eliminate fluoroquinolone antibiotics from the water matrixes re-mains a challenge. Therefore, a novel dual-defects modified 2D/2D TiO2/g-C3N4 Van Der Waals heterojunction was constructed via surfactant-assisted and NaBH4 thermal treatment, in which the TiO2-x were anchored on the defect-rich g-C3N4 sheets with an atomic-level intimate heterojunction interface. The as-prepared Dual-defects modified TiO2/g-C3N4 exhibited the highest catalytic activity and 94.5 % levofloxacin (LVFX) was decomposed within 15 min. The outstanding performance could be primarily ascribed to a special 2D structure, wide visible light response range, and high-efficiency separation and transfer of photogenerated carriers. Meanwhile, pho-tocatalytic activity under different conditions was also studied, and the presence of CO32- and pH values exhibit an obvious impact on catalytic activity. The possible LVFX degradation pathways were proposed, and the toxicity of the degradation produces was assessed via the quantitative structure-activity relationship (QSAR) method. Finally, a possible photocatalytic mechanism in dual defective TiO2/g-C3N4was proposed.