Modification Of Cadmium Sulfide And Molybdenum Sulfide Photocatalytic Materials And Their Photocatalytic Performance Under Visible Light

With the rapid development of the economy society and the improvement of human living standards,the use of medicines and personal care products had increased dramatically.Due to the excretion of people or animals,the unreasonable disposal of waste drugs,and the imperfection of sewage treatment technology,it was frequently detected in water environment.Over time,it will adversely affect the entire ecosystem and human health.In recent years,semiconductor photocatalysis technology had been widely used as a green,environmentally friendly and efficient method to degrade the pollutants in waste water.Cadmium sulfide（Cd S）and molybdenum disulfide（Mo S₂）have excellent photocatalytic properties,and they have attracted much attention because of their low cost and abundant raw material sources.However,although Cd S can absorb visible light,it was inherently unstable and had low light utilization efficiency.The surface of Mo S₂had more active sites and the material itself was stable,but it cannot separate the photogenerated carriers well,which cause low photocatalytic activity.Therefore,the development of a new noble metal semiconductor catalyst with high photocatalytic efficiency was of great significance for the degradation of organic pollutants.This paper intended to improve the photocatalytic activity of Cd S by synthesizing Cd Zn S/Mo S₂and carbon quantum dots（CDs）/Mo S₂/Cd S composite photocatalytic materials,and applied it to diclofenac（DCF）and naproxen（NPX）.In the degradation of PPCPs,the main research contents and results are as follows:（1）In this work,a core-shell heterojunction Mo S₂/Cd_0.9Zn_0.1S photocatalytic material was successfully synthesized via a simple one-step hydrothermal method.The introduction of Mo S₂led to a significant improvement in the photocatalytic degradation of diclofenac（DCF）.It was confirmed that 0.1%loading content of Mo S₂achieved an optimal photocatalytic efficiency of 86%in the degradation of DCF under visible light irradiation,which was 1.8 times higher than that of Cd_0.9Zn_0.1S.The Mo S₂/Cd_0.9Zn_0.1S heterostructured composites possessed improved photocatalytic properties,which implied that the combination of Cd_0.9Zn_0.1S and Mo S₂shortened the carrier transport pathway and facilitated the separation efficiency of electrons and holes.Reactive species（RS）scavenging experiments and electron spin resonance（ESR）demonstrated that superoxide radicals(O₂^·-)and electron holes（h⁺）played predominant roles throughout the DCF degradation process.The primary intermediates were explored through HRAM LC/MS/MS,and a transformation pathway was tentatively proposed.This study promoted the application of an economical,highly efficient and visible light driven Mo S₂co-catalyst for the degradation of organic contaminants.（2）Carbon quantum dots（CQDs）have superior optical properties and can improve the activity of photocatalysts effectively.The CQDs/Mo S₂/Cd S composite photocatalyst was successfully prepared by a simple calcination-hydrothermal method,which were applied to the degradation of naproxen（NPX）under visible light.The results show that CQDs/Mo S₂/Cd S composite photocatalytic materials exhibited superior photocatalytic activity compared to pure Cd S and composite Mo S₂/Cd S.When the loading of carbon quantum dots was 0.5%and the loading of molybdenum sulfide was 20%,the degradation of naproxen by CQDs/Mo S₂/Cd S composite photocatalyst showed the highest activity.The degradation rate was reached 84%,which was pure 4 times of Cd S and 1.47 times of 20%Mo S₂/Cd S composite.