磺胺类抗生素使用广泛且在传统污水处理工艺中不能有效去除，因而在水环境中频繁检出。芬顿（Fenton）技术是一种有效去除难降解污染物的高级氧化技术，然而，传统Fenton反应需要酸性条件，并且产生含铁污泥，这限制了其实际应用。本论文制备了3种Ti3C2Tx MXenes材料和相应的ZnCdS/MXene复合光催化剂，利用场发射扫描电镜、X射线光电子能谱、光电化学测试等手段对所得材料的表观形貌、结构组成等进行了表征，研究了ZnCdS/MXene光催化产H2O2的性能；构建了光-Fenton体系，探究了磺胺甲恶唑（SMX）的光催化降解特性，考察了光催化产生H2O2性能和光-Fenton降解SMX的影响因素，并探讨了ZnCdS/MXene光催化及降解污染物的反应机理，得出的主要结论如下： （1）制备了Ti3C2Tx、氮掺杂Ti3C2Tx和硫氮共掺杂Ti3C2Tx等3种MXenes材料，并与ZnCdS复合制备了相应的ZnCdS/MXene（ZCST、ZCSNT和ZCSSNT）复合光催化剂。借助多种表征手段，证实了Ti3C2Tx的成功合成及S、N元素的成功掺杂；复合光催化剂中引入MXenes可以抑制ZnCdS的团聚并提高其光吸收能力，且MXenes与ZnCdS形成的肖特基异质结，有助于光生载流子的分离。 （2）发现MXenes与ZnCdS复合构成光催化剂显著提升了ZnCdS产H2O2的性能。与单独的ZnCdS相比，ZCST、ZCSNT和ZCSSNT产生H2O2的性能分别提升了约40%、74%和108%；与Ti3C2Tx相比，元素掺杂Ti3C2Tx能更加有效地增强复合光催化剂的催化活性和光利用率，且硫氮共掺杂的强化作用胜于氮掺杂。 （3）发现ZnCdS/MXene复合光催化剂促进了Fe3+/Fe2+的转化，减少了光-Fenton体系中Fe2+的用量及含铁污泥的产生。3种复合光催化剂均能在3.0-8.5的pH范围内高效降解SMX且具有良好的稳定性；确定了多种因素对ZnCdS/MXene光-Fenton体系降解SMX的影响。 （4）揭示了ZnCdS/MXene的光催化机理及磺胺类抗生素污染物的降解机理。MXenes对ZnCdS催化活性的增强主要是抑制了光生载流子的复合、加速了电子-空穴对的分离和转移、提升了对2e-氧还原反应的选择性、降低了H2O2生成反应的能垒并增强了活性位点对氧的吸附。根据检测出的9种SMX降解中间产物，推测了SMX可能的降解路径，降解SMX的主要活性物种是?OH。
Sulfonamide antibiotics are widely used and can’t be effectively removed by conventional wastewater treatment techniques, leading to frequent detection in the aqueous environments. The Fenton process represents an effective advanced oxidation process for the removal of recalcitrant pollutants. However, the traditional Fenton reaction requires acidic conditions and produces iron-containing sludge, limiting its practical application. In this study, three Ti3C2Tx MXenes materials and the corresponding ZnCdS/MXene composite photocatalysts were prepared, and the structural compositions and surface morphologies of the resulting materials were characterized using field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and photoelectrochemical tests, etc. The performance of ZnCdS/MXene photocatalytic production of H2O2 was investigated, and photo-Fenton systems were constructed to explore the photocatalytic degradation properties of sulfamethoxazole (SMX). The effects of different factors on the photocatalytic production of H2O2 and the photo-Fenton degradation of SMX were investigated. Additionally, the catalytic mechanism of ZnCdS/MXene photocatalysts and the degradation mechanism of pollutants by photo-Fenton systems were discussed. The major conclusions are as follows:(1) Three MXenes materials, including Ti3C2Tx, nitrogen-doped Ti3C2Tx, and sulfur-nitrogen co-doped Ti3C2Tx, were prepared, and the corresponding ZnCdS/MXene (ZCST, ZCSNT, and ZCSSNT) composite photocatalysts were synthesized by compounding with ZnCdS. Multiple characterization techniques were employed to confirm the successful synthesis of Ti3C2Tx and the successful doping of S and/or N elements. The introduction of MXenes into composite photocatalysts inhibited the aggregation of ZnCdS and improved its light absorption ability. Moreover, the Schottky heterojunction formed by MXenes and ZnCdS facilitated the separation of photo generated carriers. (2) It was observed that the composites of MXenes and ZnCdS significantly enhanced the performance of ZnCdS for H2O2 production. Compared to the initial CdS, the performance in H2O2 production of ZCST, ZCSNT, and ZCSSNT was improved by about 40%, 74%, and 108%, respectively. Compared to Ti3C2Tx, element-doped Ti3C2Tx (nitrogen-doped Ti3C2Tx and sulfur-nitrogen co-doped Ti3C2Tx) could more effectively enhance the catalytic activity and light utilization efficiency of the composite photocatalysts. Moreover, the enhancement effect of sulfur-nitrogen co-doping was superior to that of nitrogen doping alone.(3) It was found that the ZnCdS/MXene photocatalyst promoted the conversion of Fe3+/Fe2+, reducing the amount of Fe2+ and the production of iron-containing sludge in the photo-Fenton system. All three composite photocatalysts demonstrated efficient degradation of SMX in the pH range of 3.0 to 8.5 and exhibited good stability. The effects of various factors on the degradation of SMX by the ZnCdS/MXene photo-Fenton systems were determined.(4) The catalytic mechanism of three ZnCdS/MXene photocatalysts and the degradation mechanism of sulfonamides pollutants by the photo-Fenton process were revealed. The enhancement of the catalytic activity of ZnCdS by MXenes was primarily attributed to the inhibition of photogenerated charge carrier recombination, the acceleration of the separation and transfer of electron-hole pairs, the enhancement of the selectivity for the 2e- oxygen reduction reaction, the lowering of the energy barrier for the H2O2 generation reaction and the enhancement of the adsorption of oxygen at the active sites. The possible degradation pathways of SMX were hypothesized based on the nine SMX degradation intermediates detected, and the main active species for degrading SMX was ?OH.
