Synthesis Of Enhanced CdS Based Materials With Surface Modification And Its Study Of Photocatalytic Properties

In recent years,photocatalysis is considered as a hot and promising technology in environmental purification and production of clean energy.Cadmium sulfide（CdS,2.42e V）is a semiconductor material with unique optical,electrical and chemical properties,which has great potential in photocatalytic degradation of pollutants.However,the photochemical corrosion of CdS is serious,which largely limits to photocatalytic activity.In view of the problems of CdS,CdS with different morphologies were synthesized by hydrothermal solvothermal method with different surface modifiers（EDTA,L-cysteine,PEG 2000,SDS）and solvents(glycol,ethylenediamine,V_En:V _{deionized water}=1:1,deionized water)in this paper.The possible growth mechanism of CdS was analyzed,and the photocatalytic properties of CdS with different morphologies were studied.On this basis,CdS/SnO₂composites were synthesized by adjusting the molar ratio of CdS to SnO₂and different surface modifiers（EDTA,L-cysteine,PEG 2000,SDS）,and it was expected that RhB solution could be effectively degraded by CdS/SnO₂photocatalyst.The main contents are as follows.（1）Particles-like,rod-like and branch-like CdS were synthesized by hydrothermal solvothermal method in different solvents,and ball-like and flake-like CdS were synthesized by different surface modifiers.The growth mechanism of CdS with the assistance of EDTA and L-cysteine was analyzed:the binding rate of Cd²⁺and S^2-may be the main factor for the morphology transformation of CdS.The efficiency of photocatalytic degradation of ball-like CdS was higher than flake-like and branch-like CdS.（2）CdS/SnO₂ composites were synthesized by hydrothermal method with different surface modifiers and adjusting the molar ratio of CdS to SnO₂.The results showed that the efficiency of photocatalytic degradation of CdS/SnO₂composite was higher than CdS in the photocatalytic degradation of RhB solution.In addition,when CdS/SnO₂photocatalysts were synthesized with different surface modifiers to degrade RhB solution,the efficiency of the photocatalytic of the samples was improved.When CdS/SnO₂photocatalyst were synthesized with SDS to degrade RhB solution,the degradation efficiency of the sample reached 88.4%after 180 min of illumination,which was significantly higher than CdS,and CdS/SnO₂composites was synthesized by other surface modifiers（EDTA,L-cysteine,PEG 2000）.Moreover,the possible photocatalytic mechanism of CdS/SnO₂composite was explored:the CdS/SnO₂composite with the assistance of 0.1mmol SDS had microporous structure and high surface area,which increased the area of photocatalytic reaction;Besides,the CdS/SnO₂composite with the assistance of 0.1mmol SDS can form a good heterojunction at the interface,which promotes effective charge separation and prolongs the carrier lifetime.These two reasons may lead to the increase of efficiency of photocatalytic degradation.