Construction of Bi2MoO6/CoWO4 Z-scheme heterojunction for high-efficiency photocatalytic degradation of norfloxacin under visible light: Performance and mechanism insights

In this work, we employed Bi2MoO6 and CoWO4 to fabricate a direct Z-scheme Bi2MoO6/CoWO4 (BMC-x) heterostructure with high redox potential for norfloxacin (NOR) photodegradation. Under visible light (λ > 420 nm) illumination, BMC-x composites displayed excellent photodegradation performance toward norfloxacin. The photodegradation rate of norfloxacin by BMC-30 reached 97.1% within 60 min of illumination, and the apparent rate constant (0.0588 min−1) was 2.42 and 17.8 times those of Bi2MoO6 and the CoWO4, respectively. The photocatalytic performance of BMC-x nanocomposites was mainly ascribed to the more efficient utilization of electrons (e−) and holes (h+) due to the fabrication of a direct Z-scheme heterostructure. In addition, the mechanisms of NOR degradation were investigated through active species capture experiments and ESR analyses, indicating that O− 2and h+ worked as primary components. Furthermore, the NOR photodegradation pathways were investigated by density functional theory (DFT) and intermediates analysis. More importantly, depending on the QSAR predictions and E.coli cultivation, the comprehensive toxicity of the final intermediates was lower than that of the parent. Thus, this work offers a feasible idea for the design and construction of Z-scheme heterojunctions for the highly effective degradation of emerging contaminants in water.