The Preparation And Photocatalytic Performance Of Composites Containing CdS And MOF

Many toxic substances generate in the reaction of selective oxidation of aromatic alcohol when traditional oxidants are used.However,aromatic aldehyde can be made from aromatic alcohol easily and environmentally by photocatalytic technology.Traditional photocatalysts have lower selectivity and weaker absorption capacity of visible-light.Thus,preparing efficient photocatalysts has been the main research topic.As an photocatalyst,CdS has attracted many researchers.Under visible-light irradiation,CdS is excited to generate holes that have a strong ability of oxidation.However,CdS can’t show its efficient photocatalytic activity completely due to its aggregation.MOFs have larger specific surface area and high porosity.Thus,MOFs have the potential to be the support of CdS for improving the photocatalytic activity of CdS.It is well known that Ti-based MOFs has larger specific surface area,high porosity and excellent stability.Thus,MIL-125(Ti)and NH2-MIL-125(Ti)are chosen to be the supports for CdS in this paper.Then CdS/ MOFs composites are prepared by photochemical method.The conversion of benzyl alcohol to benzaldehyde is used to test the photocatalytic activity and stability of the composites.Some research results are illustrated as below:1.Compared with CdS,CdS-MIL-125(Ti)prepared by photochemical method has stronger absorption capacity of light and an obvious red-shift in the area of visible light.The conversion of benzyl alcohol to benzaldehyde has reached 20.1% with no byproduct when CdS-MIL-125(Ti)was applied to be photocatalyst.While under the same condition,the conversion are 9.2% and 3.5% using CdS or MIL-125(Ti)as the photocatalyst,respectively.Furthermore,the leaching of Cd and Ti are just 0.27% and 0.082% after the composites were used three times.Thus,combining CdS with MIL-125(Ti)by photochemical method really can improve the activity of CdS,and the composites also have strong stability.2.Then the composites CdS-NH2-MIL-125(Ti)were also prepared by photochemical method.The result shows that the conversion of of benzyl alcohol to benzaldehyde is 27% when CdS-NH2-MIL-125(Ti)-2 is used.Meanwhile,the conversion reaches 18.5% when NH2-MIL-125(Ti)is used as photocatalyst.It is found that CdS gains more effective photoactivty after combining with NH2-MIL-125(Ti).