Highly Efficient Photocatalytic Degradation Of Norfloxacin Via Bi₂Sn₂O₇/PDIH Z-scheme Heterojunction:Influence And Mechanism

The serious contamination caused by antibiotics has attracted considerable attention in recent decades.Many methods have been used in the treatment of antibiotic pollution in water bodies.Photocatalysis is a cutting-edge environmental protection alternative that can break down organic contaminants into non-toxic tiny molecules,which has received great attention.Recently,inorganic/organic photocatalysts with the advantages of structural tunability and good electron transport capacity have been extensive ly studied.Several inorganic/organic heterostructures have been developed for antibiotic degradation.Bi₂Sn₂O₇,a typical Bi-based semiconductor material,has received considerable attention owing to its high oxidation and pyrochlore structure.It has extraordinary photocatalytic activity for the degradation of organic contaminants and the oxidation of water.However,the widespread use of Bi₂Sn₂O₇ has been hampered by its inefficient photogenerated charge carrier separation and subsequent weak photocatalytic performance.Perylenediimide（PDI）as organic semiconductors are favored by many researchers owing to easy modification,optical performance,tenability,structural variety,abundant elements,and low cost.Therefore,it seems like an interesting idea to construct an efficient Z-scheme photocatalyst by combining PDIH with Bi₂Sn₂O₇ for contaminant degradation.In this study,Bi₂Sn₂O₇/PDIH Z-type heterojunction photocatalysts were synthesized by electrostatic self-assembly and solvothermal methods,and h igh photocatalytic activity for norfloxacin was obtained.The degradation rate of norfloxacin reached 98.71%within 90 minutes under visible light.The apparent rate constants of norfloxacin(0.04903 min^-1)were 3.65 and 20 times higher than those of PDIH and Bi₂Sn₂O₇,respectively.Meanwhile,XPS,electrochemical,Photoluminescence spectroscopy,and electron paramagnetic resonance results showed that the Z-scheme charge-transfer process facilitated the spatial carrier separation and preserved redox capability.h⁺,·O₂^-,and·OH were the main active species in the degradation reaction.In addition,the degradation pathway of norfloxacin and the toxicity of intermediates were also evaluated,and it was found that with the progress of the reaction,the contami nation toxicity of intermediates could finally be decomposed into low-toxic products.Finally,from the investigation of the effects of different water matrices,it was found that the addition of ionic species,low concentrations of nutrients,and natural organic matter are beneficial to the photocatalytic degradation of NOR by Bi ₂Sn₂O₇/PDIH,and Bi₂Sn₂O₇/PDIH maintained high efficiency in natural raw water.This work enriched inorganic/organic heterojunction engineering for PDIH and provided the enormous potential for combining the Bi₂Sn₂O₇ with PDIH to address the antibiotic pollution issues in the actual water treatment.