Preparation of BiVO4/CO32−-Bi2O2CO3 heterojunctions for enhanced photocatalytic activity in the degradation of levofloxacin under visible light

The issue of levofloxacin elimination from wastewater has become significant. In this study, a series of BiVO4/CO32−-Bi2O2CO3 composite photocatalysts were constructed by the hydrothermal method for the photocatalytic degradation of levofloxacin. Various methods were used to investigate the morphology, composition, functional groups, optical, and photoelectrochemical properties of BiVO4/CO32−-Bi2O2CO3. In the photocatalytic degradation experiment, the best photocatalytic activity was exhibited when the molar ratio of BiVO4 to CO32−-Bi2O2CO3 was 0.8 (0.8VCBOC). The photocatalytic degradation efficiency of levofloxacin is 78% within 90 min under 300 W Xenon lamp (λ ≥ 420 nm), which is 1.24 times that of CO32−-Bi2O2CO3 (63%). The free radical capture experiment and electron spin resonance tests indicated that·O2- is the active species in the photocatalytic degradation of levofloxacin, and the Z-scheme heterojunction model was subsequently proposed. The photocatalytic activity of BiVO4/CO32−-Bi2O2CO3 was improved through the formation of the heterojunction and the expansion of the absorption rang. Based on LC–MS analysis, possible degradation pathways of levofloxacin in the 0.8VCBOC system were proposed. Moreover, excellent cyclic stability was demonstrated by the 0.8VCBOC catalyst in the cyclic stability experiment. This work presents a method for the simple and feasible construction of visible-light-induced photocatalysts based on CO32− self-doped Bi2O2CO3 for the degradation of levofloxacin.