Preparation Of Modified Cadmium Sulfide And Its Photocatalytic Performance

Compared with other semiconductor materials,cadmium sulfide（CdS）has the advantages of relatively narrow band gap（2.4 e V）and effective absorption of sunlight less than 520 nm wavelength.However,its imperfection limits its application in real life.First of all,Cd is a toxic heavy metal,which will further damage human life safety through the food chain after our water environment is polluted.Therefore,it must be effectively recycled and treated after the reaction.Secondly,another element in the monomer is easy to be oxidized into monomer with the reaction system,and its catalytic effect will gradually weaken with time.Finally,the photogenerated electrons and holes generated by light stimulation are particularly easy to reassemble in the process of migration or surface,so the distance application of this material is still a big problem in real life.To solve the above problems,researchers in the global field used different methods to study the modification.Although many problems have been improved,there are still some gaps in the application of CdS photocatalytic technology in the actual environmental governance.In this paper,carbon materials have similar conductive properties to metals,which can not only transfer photogenerated electrons quickly,but also have large specific surface area to provide more active sites.Carbon materials and semiconductor materials are used to form heteroassociation to modify them.Specific research contents are as follows:（1）In this paper,the bowl of porous carbon was prepared by silica pellet template in the early stage,and the C/CdS composite photocatalyst was prepared by simple hydrothermal synthesis method in the later stage.The structural composition,morphological characteristics and light capture ability of the composites were analyzed by XRD,XPS,FTIR,SEM,BET and UV-Vis.BET,VB-XPS,energy band structure diagram and other data show that C/CdS has higher specific surface area and corrected valence band compared with pure CdS.Furthermore,the optimal carbon loading and photocatalytic degradation performance were determined by photocatalytic degradation of rhodamine B.The results showed that the best degradation effect was achieved when the loading amount was 1%,and the reaction rate constant was 2.3 times that of pure cadmium sulfide.The principle of photocatalytic degradation of pollutants was further understood by the capture experiments with free radical trapping agents,and the key active substances in the reaction were determined.（2）In this paper,using cadmium chloride,thiourea,sodium dodecylbenzene sulfonate,ethylenediamine and nano onion carbon as reactants,MCNOs/CdS magnetic photocatalyst was successfully prepared by simple hydrothermal method.The microstructure,chemical composition and light absorption properties of the composite were analyzed by XPS,N₂adsorption-desorption,FTIR,XRD,SEM and UV-Vis,and the paramagnetism of the composite was tested by hysteresis loop.The results show that the better magnetization is convenient for the recovery of the photocatalyst.The photocatalytic performance and stability of the composites were evaluated by using RhB as the degradation pollutant under simulated sunlight irradiation.The results show that the photocatalytic performance and stability are greatly improved when the MCNOs loading is 3%,and the reaction rate constant of MCNOs is 3.1times that of pure cadmium sulfide.This is mainly attributed to the good electrical conductivity of MCNOs,which improves the electron transport and migration ability in the composite material,and greatly reduces the recombination rate of photogenerated carriers.The degradation mechanism of MCNOs/CdS magnetic photocatalyst was analyzed under the optimum experimental conditions and the key active substances in the reaction system were determined.