Synthesis Of CdS-based Catalysts Supported On Nan-CeO₂ And Study On Degradation Of Formaldehyde At Room Temperature

With the rapid economic and technological development,large quantities of pollutants are released into waste water and atmosphere.Formaldehyde（HCHO）,a volatile organic compound（VOCs）,is often used in industries such as painting,wood processing and textiles.However,excessive use causes huge pollution of water resources and indoor air,posing irreversible risks to ecological safety and human health.Therefore,there is a great need to find an efficient way to degrade formaldehyde.Currently,photocatalytic degradation is emerging as one of the most promising methods for the purification of HCHO and is widely used due to its mild reaction conditions,the fact that the catalyst is a cheap and easily accessible semiconductor and the fact that it can convert HCHO into non-toxic and non-hazardous H₂O and CO₂.Conventional CdS has low photocatalytic activity due to the high complexation rate of photogenerated electron-hole pairs and low quantum efficiency.This paper constructs interfacial phase junctions between the two phases of CdS and heterojunction structures dependent on the band shift of the two semiconductors,with consequent enhanced photocatalytic degradation of pollutants through efficient charge transfer between the semiconductors.In this work,the basic physicochemical properties such as density,viscosity and refractive index of（polyethylene glycol 400+1,3-diaminopropane）low eutectic solvent were firstly investigated to prove the existence of hydrogen bonding between molecules of the binary system.On this basis,CO₂ storage materials（CO₂SM）and carbon disulfide storage materials（CS₂SM）were prepared by capturing CO₂ and CS₂ at a 1:1 alcohol to amine molar ratio.The optimum conditions for the preparation of the composite catalysts were obtained based on the results of single-factor and response surface studies:a CS₂SM concentration of 7 g/L,a reaction time of 4 h and a reaction temperature of 95°C.The composite catalysts were prepared by stirring with Cd²⁺,CeO₂ and CS₂SM to obtain CdS/CeO₂.Under these conditions,the degradation rate of 1 mg/L formaldehyde solution by 0.05 g of the composite catalyst CdS/CeO₂ was 92.0%,which was 8.6 and 17.0 times higher than that of pure CdS and CeO₂,respectively,and kinetic data for the degradation of HCHO by the composites were also fitted.To further improve the degradation performance of the photocatalyst for HCHO,the Co S co-catalyst was introduced into the system for doping modification,and the Co S-（CdS/CeO₂）ternary composite photocatalyst was obtained.The degradation performance of the composite catalyst was tested under different doping ratios at room temperature and visible light,and the degradation rate of the Co S-（CdS/CeO₂）photocatalyst reached 99.5%for 1 mg/L HCHO solution.This work not only provides important data on the basic physicochemical properties of the（PEG400+PDA）low eutectic solvent,but also provides a new reference for the preparation process of CdS-based composite photocatalysts and a new idea for the efficient and low-cost degradation of HCHO at room temperature.