XRF results of ZnO/BiOBr/Bi2S3 synthesis.

The ZnO/BiOBr/Bi2S3 dual Z-scheme heterojunction was synthesized via the solvothermal method, and the photocatalytic removal of cefixime (CFX) was investigated using the nanocomposite. Structural and morphological studies were conducted using XRD, FTIR, Raman spectroscopy, XRF, FE-SEM, TEM, UV-Vis DRS, PL, and BET. The results indicated that the ZnO/BiOBr/Bi2S3 exhibited a synergistic effect, reducing the band gap energy to 2.70 eV and enhancing charge separation in comparison with individual and binary components. The Raman peak shifts confirmed the formation of heterojunction among the components. Optimization of the mass ratio through screening experiments resulted in an optimum composition of 30 wt% ZnO to BiOBr/Bi2S3, achieving a 75% removal efficiency. CFX adsorption on the nanocomposite followed a monolayer mechanism, with a maximum adsorption capacity of 15.32 mg.g-1. In addition, approximately 96% CFX removal was achieved using the immobilized ternary ZnO/BiOBr/Bi2S3 heterojunction on graphite under optimal operating conditions. The and h+ for the suspended and the and OH for the immobilized system play the major role in CFX degradation.

本研究通过溶剂热法合成了ZnO/BiOBr/Bi2S3双Z型异质结，并以该纳米复合材料为催化剂，探究了其光催化去除头孢克肟（cefixime，CFX）的性能。采用X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、拉曼光谱、X射线荧光光谱（XRF）、场发射扫描电子显微镜（FE-SEM）、透射电子显微镜（TEM）、紫外-可见漫反射光谱（UV-Vis DRS）、光致发光光谱（PL）及比表面积分析（BET）对其结构与形貌进行了表征。结果表明，与单一组分及二元组分相比，ZnO/BiOBr/Bi2S3表现出显著的协同效应，将禁带宽度降至2.70 eV，并提升了电荷分离效率。拉曼峰位移现象证实了各组分间异质结的成功构建。通过筛选实验对质量配比进行优化，得到最优配方为ZnO占BiOBr/Bi2S3的30 wt%，此时头孢克肟去除率可达75%。CFX在该纳米复合材料上的吸附遵循单分子层吸附机制，最大吸附容量为15.32 mg·g⁻¹。此外，在最优操作条件下，将该三元ZnO/BiOBr/Bi2S3异质结负载于石墨载体后，可实现约96%的CFX去除率。悬浮体系中的超氧阴离子自由基与空穴（h⁺），以及负载体系中的羟基自由基（·OH）在CFX降解过程中发挥了主导作用。