A novel Ag3BiO3/ZnO/BC composite with abundant defects and utilizing hemp BC as charge transfer mediator for photocatalytic degradation of levofloxacin

In this work, a novel n-n heterojunction Ag3BiO3/ZnO/BC with abundant defects was prepared via a facile hydrothermal strategy and applied for photocatalytic degradation levofloxacin (LFX) antibiotics. After optimization on the composition of ZnO, biochar (BC) and Ag3BiO3, the optimal 0.2-Ag3BiO3/ZnO/BC shows superior photocatalytic activity, yielding a higher removal efficiency of LFX ∼ 95.8 % in 120 min than those of pure ZnO (9.4 %), BC (32.1 %) and Ag3BiO3 (14.3 %). Additionally, 0.2-Ag3BiO3/ZnO/BC also shows prominent stability and reusability for running 5 times. The superior photocatalytic properties can be associated with the abundant defects, stronger light absorption and matched bandgap energy levels of the 0.2-Ag3BiO3/ZnO/BC. Furthermore, the formed n-n type heterojunction between ZnO and Ag3BiO3 in Ag3BiO3/ZnO/BC can efficiently promote the separation and transfer of the photogenerated electron/hole (e-/h+) pairs and indirectly decrease the charges recombination. Meanwhile, the BC with excellent conductivity can act as a charge transfer bridge for further accelerating the charges transfer between ZnO and Ag3BiO3. The possible degradation pathway of LFX was presumably proposed by conducting the liquid chromatography-mass spectrometry (LC-MS) measurement. In conclusion, this work offers a novel strategy for designing and fabricating ZnO based n-n type heterojunction photocatalysts coupled with biochar for efficiently eliminating antibiotics in aqueous.