Research On The Preparation And Photocatalytic Properties Of Ag-based Semiconductors/Ti₃C₂T_x Composite Materials

Ag-based semiconductor is a kind of good visible-light-driven photocatalytic material because of its plasma resonance effect and narrow band gap.Meanwhile,the valence-band holes of Ag-based semiconductor have strong oxidation ability,so it shows excellent photocatalytic degradation performance of pollutants under visible light conditions.However,Ag-based semiconductors have good photosensitivity and weak conduction band electron reduction ability,photogenerated electrons can easily reduce Ag+on the surface of Ag-based semiconductors to Ag0 and cause photochemical corrosion,which is not conducive to the effective utilization of photogenerated electrons,but also affects their photocatalytic stability and limits the wide application of Ag-based semiconductors.In order to improve the photocatalytic activity and stability of Ag-based semiconductors,Ag-based semiconductors/Ti3C2Tx heterojunction was constructed by introducing Ti3C2Tx as a co-catalyst,the mechanism of Ti3C2Tx to improve the performance of Ag-based semiconductors was explored,the specific research contents are as follows:(1)A new Ag2CrO4/Ti3C2Tx composite was prepared by simple precipitation method,the materials were characterized by XRD,SEM,TEM,EIS and DRS.The results showed that the pure Ti3C2Tx prepared by HF etching was accordion layered structure,and the polyhedral Ag2CrO4 nanoparticles firmly adhered to the surface of Ti3C2Tx.The photocatalytic activity of the composite under visible light was studied,the results showed that the photocatalytic activity of the composite was the highest when the content of Ti3C2Tx was 0.4 wt%which was 1.9 times that of pure Ag2CrO4.After five cycles of photocatalytic experiments,Ag2CrO4/Ti3C2Tx showed great stability.ESR and reactive specie trapping experiments showed that superoxide radicals and holes were the main active species.The mechanism of Ti3C2Tx improving photocatalytic activity of Ag2CrO4 is that photogenerated electrons on Ag2CrO4 surface transfer to Ti3C2Tx surface,which promotes the separation and utilization of photogenerated electron hole pairs on Ag2CrO4 surface and effectively inhibits the reduction of photogenerated electrons on Ag2CrO4 surface.(2)AgBr/Ti3C2Tx composites were prepared by microemulsion method and coprecipitation method,the materials were characterized by XRD,SEM,TEM and DRS,and the photocatalytic activity of these composites under visible light was studied.The results showed that the photocatalytic activity of the composite was the highest when the content of Ti3C2Tx was 1 wt%,which was 1.73 times that of pure Ag2CrO4.AgBr/Ti3C2Tx showed good stability after five cycles of photocatalytic experiments.ESR characterization showed that superoxide radicals and holes were the main active species for degradation of organic compounds in these composites.(3)AgCl/Ti3C2Tx composites were synthesized by microemulsion method and coprecipitation method,the materials were characterized by XRD,SEM,TEM and DRS,and the photocatalytic activity of these composites under visible light was studied.The results showed that the photocatalytic activity of the composite was the highest when the content of Ti3C2Tx was 1 wt%,which was 1.56 times that of pure Ag2CrO4.AgCl/Ti3C2Tx showed good stability after five cycles of photocatalytic experiments.ESR characterization showed that superoxide radicals,holes and hydroxyl radicals were the main active species for degradation of organic compounds in these composites.This study is helpful to expand the application of Ti3C2Tx in the field of photocatalysis and to improve the photocatalytic performance of Ag semiconductor.