【摘要】 为了提升CuS材料的光催化活性用来有效降解染料废水中的有机污染物，使用金属修饰法对其进行改良。以氯化铜、硫脲和DMF溶剂等为原料，通过溶剂热法合成花状CuS材料。之后利用光还原法将金属Bi负载到CuS催化剂的表面，制备出Bi/CuS光催化复合材料。通过X射线衍射仪（XRD）、透射电子显微镜（TEM）、扫描电子显微镜（SEM）等对复合材料进行表征，并以刚果红（CR）为目标降解物进行可见光催化活性研究。结果显示，用光还原法制备的Bi/CuS光催化剂始终保持球状结构，Bi元素均匀分布在其中。引入Bi可促进CuS的光吸收性能，能够有效地抑制电子空穴的复合，有利于光生载流子的分离，大大提升CuS对CR溶液的光催化降解性能。同时金属Bi在CuS催化剂上的负载量受光照还原时间的影响。当光照还原时间为45 min时合成的Bi/CuS光催化剂活性最佳，对CR的降解率可达到89.5%。此方法运用范围广泛、无二次污染，为快速降解CR溶液提供了一定的参考。更多还原

【Abstract】 Congo Red(CR), as one of azo dyes, is widely used in production because of its easy solubility in water, low cost and good dyeing effect. Traditional methods to degrade Congo red include microwave treatment, electrochemical catalysis, adsorption, and etc. However, photocatalytic technology, which uses solar energy to degrade organic pollutants and reduce carbon dioxide, presents the advantages of simplicity and no secondary pollution. It has raised the wide research of dye wastewater treatment in recent years.Among them, CuS, as a p-type semiconductor material, has the characteristics of low cost and high stability compared with other photocatalysts. Flower-shaped CuS can improve the photocatalytic efficiency by more efficient utilization of solar energy. However, CuS needs to be modified for some defects, such as easy electron-hole combination. Metal modification is one of the important ways to improve the photocatalytic activity. The existing form and content of doped metal have an important influence on the recombination of photo-generated electrons and holes, and then affect its photocatalytic activity. As a dopant, Bi has attracted much attention because of its high electron transfer efficiency, low cost and easy availability. In this study, the flower-shaped CuS material was synthesized by solvothermal method with copper chloride, thiourea and N,N-dimethylformamide as raw materials. Bi/CuS composite was prepared by photo-reduction method, and metal Bi was loaded on the surface of CuS catalyst. X-ray diffraction(XRD), scanning electron microscope(SEM), transmission electron microscope(TEM) and Zeta potential diagram were used to characterize the catalyst. The results showed that the crystallinity and purity of CuS were high, and metal Bi was successfully loaded on the surface of CuS catalyst. The prepared CuS had flower-ball/hedgehog-like morphology and good dispersibility. The spherical structure of Bi/CuS was maintained. In the optimized Bi/CuS(45) example, it could be seen that Bi elements were uniformly distributed in the composite from elemental analysis.The surface of CuS was negatively charged, and its potential could be changed from negative to positive by doping Bi metal. At the same time, Bi/CuS showed positive electricity, and pollutant CR showed strong negative electricity, resulting in the effectively adsorption of pollutants and increased reactive sites to realize the effective degradation of pollutants. In addition, the modified Bi/CuS showed positive electricity, and the Zeta potential of Bi/CuS also enhanced with the increase of illumination time, which changed the charge distribution on the catalyst surface. The comparison of UV-vis diffuse reflectance spectroscopy, photoluminescence spectra and band gap between CuS and Bi/CuS(45) showed that pure CuS had a strong broad spectrum absorption peak. It facilitated the electrons on the surface of copper sulfide excited from valence band to conduction band. Meanwhile, the light absorption intensity of Bi/CuS(45) within 300～800 nm was stronger than that of pure CuS. Therefore, the introduction of Bi could promote the light absorption performance of CuS. In addition, metal Bi doping induced the decreased PL intensity, since the photo-generated electrons transferred from CuS surface to metal Bi, and realized the electron quenching. Therefore, doping Bi could effectively inhibit the recombination of electron-hole pairs, prolonged the life of photo-generated carriers, and then promoted the improvement of photocatalytic activity. The decrease of the band gap width after metal Bi loading was beneficial to the separation of photo-generated carriers and the improvement of the catalytic activity. During the degradation of CR, CuS, Bi/CuS(30), Bi/CuS(45), Bi/CuS(60) and Bi/CuS(75) catalysts presented the higher activity than that without catalyst. Comparing to the low degradation efficiency of CR on CuS of only 17.8%, the degradation efficiencies were 82.5%, 89.5%, 86.6% and 45.4% on Bi/CuS(30), Bi/CuS(45), Bi/CuS(60) and Bi/CuS(75), respectively. Especially, Bi/CuS(45) presented the highest activity with more than four times than CuS. Therefore, doping Bi on CuS could greatly improve the photocatalytic degradation of CR solution. Bi/CuS photocatalyst effectively improved the adsorption capacity and light harvesting, and inhibited the recombination of photo-generated carriers. As a result, the photocatalytic performance was greatly improved and it showed the application prospect for the removal of organic pollutants.更多还原