| In China,the Cr(?)pollution have resulted in an enormous threat to human health because of the toxicity and non-biodegradable.Photocatalytic reduction method is a kind of green and low-cost method for Cr(?)removal.Regarding semiconductor photocatalysts,CdS and SnS2 are widely used in photocatalytic reactions due to its relatively narrow bandgap and strong visible-light absorption capability.One of the greatest challenges is how to reduce the recombination of photogenerated electron-holes and photocorrosion.Nowadays,the supported photocatalysts are widely used as effective photocatalysts to solve the pollution of the environment.Recently,our group found that the MOFs could sensitize CdS under visible light irradiation and ehance the photocatalytic activity.Compared with MOFs,metal-organic aerogel(MOA)is a novel material with large specific surface area and good optoelectronic properties.Therefor,CdS decorated MO A were synthesized by different motheds.Based on the dye sensitization and template methods,herein we present a study on red cabbage pigment(RCP)inserted CdS/TiO2 nanocomposites and directly use(RCP)as a structure-directing agent.In order to further reduce the toxicity of the photocatalytic reaction system,the SnS2 and SnS2/TiO2 nanocomposites were prepared by adjusting the concentration of the reactants.The materials were characterized by a combination of physicochemical techniques The relationships between characteristics and photocatalytic reduction of Cr(VI)over the samples were discussed.The main contents are as follows:(1)CdS decorated MOA were prepared by one-step method and two-step loading method.The BET surface area of CdS/MOA prepared by one-step method was 714 m2g-1,which was 2-fold higher than that of CdS/MOA obtained by two-step method.It avoids the problem that the reduction of specific surface area in the material prepared by two-step method.Under visible light irradiation,the photocatalytic reduction rate of Cr(VI)(10 mg/L)over CdS/MOA(Cr)was 99%,which was higher than that of MOA(Cr)and the embedding of CdS on MOFs material.This is mainly due to the MO A(Cr)carrier could sensitize CdS under visible light irradiation;(2)The TiO2 nanocomposites were prepared by using red cabbage pigment as sensitizating and template agent.Under visible-light irradiation,the photocatalytic reduction rate of Cr(?)over nanocomposites was 98%with formic acid as hole sacrifice agent,which was approximately 12.3-fold higher than that of pure TiO2.The CdS/TiO2 was perepared by the same method.Under visible light irradiation,the photocatalytic reduction rate of Cr(?)(50 mg/L)over CdS/TiO2 was 78%without sacrificial agent.The photocatalytic reduction rate over RCP templated CdS/TiO2 was 93%.After photocatalytic reaction,the concentration of Cd in the solution was greatly reduced.Compared with CdS/MOA(Cr),the photocatalytic activity of RCP templated CdS/TiO2 is improved and the photocorrosion phenomenon is further suppressed;(3)SnS2 and SnS2/TiO2 was prepared by a one-step solvothermal method.The specific surface area(225m2g-1)of SnS2/TiO2 was higher than that of pure TiO2 and SnS2.Under visible light irradiation,the photocatalytic reduction rate of Cr(?)(50 mg/L)over SnS2/TiO2 was 80%,which was 3.6?4.3?3.5 and 3.6-fold higher than that of nS2/MOA(Cr),SnS2/MOA(Al),SnS2/MIL-100 and pure SnS2 material,respectively.After photocatalytic reaction,no Sn was detected in the solution.In this paper,the study of visible light photocatalytic reduction of Cr(?)over CdS embedded on MOA has not been reported before.This provides a photocatalyst with high activity and a sample synthesis method for application of MOA.Meanwhile,the study of RCP templated CdS/TiO2 and SnS2/TiO2 provide a new perspective for further improving the photocatalytic activity and reducing photocorrosion phenomenon. |
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