Highly efficient photocatalytic degradation of levofloxacin by novel S-scheme heterojunction Co3O4/Bi2MoO6@g-C3N4 hollow microspheres: performance, degradation pathway and mechanism

Block or flake photocatalysts are often prepared in such a way that agglomeration occurs, resulting in fast rate of photogenerated electron-hole complexation greatly reduces photocatalytic performance. Therefore, a rational design of the catalyst structure is beneficial to improve its photodegradation performance. In this paper, we reported for the first time new S-scheme heterojunction Co3O4/Bi2MoO6@g-C3N4 hollow microspheres. The introduction of the co-catalyst Co3O4 creates an internal electric field between Bi2MoO6 and g-C3N4, which more efficiently promotes the separation of photogenerated electrons and holes to accelerate carrier transfer and thus improves the overall performance of the composites. Under visible light irradiation, Co3O4/Bi2MoO6@g-C3N4 hollow microspheres degraded levofloxacin (LVFX) by up to 95.21%. After 3 cycles the degradation rate was still above 80% and the XRD spectrum did not change significantly, they are extremely stable. More importantly, the toxicity of the final product of each pathway was found to be lower than that of the parental species after intermediate testing and toxicity evaluation. The present work also suggests possible transfer pathways and degradation mechanisms for photogenerated carriers. The work provides a new idea for the efficient degradation of antibiotics by S-scheme nanocomposites.