Fabrication And Photocatalytic Activity Of Ag-based Composite Materials

Photocatalysis technology has great potential in environmental remediation,and it is a hot research issue in the field of environmental protection.Ag-based photocatalytic materials show excellent activity in photocatalytic degradation of organic pollutants and photocatalytic inactivation of bacterials,and therefore it attracts much attention and many efforts have been made in the synthesis of Ag-based photocatalysts.However,most of the Ag-based materials suffered from the drawbacks of limited visible-light response ability and photo-induced instability,which limits their practical application.As a matter of fact,constructing Ag-based composites with others semiconductors having matched bang gap could not only enhance the light absorption but also improve the stability of Ag-based photocatalyst,and finally promote the coresponding photocatalytic property.In this thesis,three different kinds of Ag-based composite photocatalysts were sucessfully syntherized and characterized.Furthermore,the photocatalytic activity,stability,and possible photocatalytic mechanism were investigated in detail.The results were summarized as following:1.Ag₂O/SnO₂ composite photocatalysts with different mass ratio were synthesized by deposition-precipitation method.The composition and structure of the obtained products were characterized by X-ray powder diffraction?XRD?and scanning electron microscope?SEM?.It was found that Ag2 O nanoparticles were dispersed on the surface of SnO₂ nanoplates uniformly.The photocatalytic activity of Ag₂O/SnO₂ was evaluated by photodegradation of RhB solution under visible irradiation.21.8 wt% Ag₂O/SnO₂ products showed higher photocatalytic activity compared to pure Ag2 O and SnO₂,and it displayed excellent stability and repeatability because it still showed good photocatalytic property even after 5 photodegradation cycles.Furthermore,the 21.8 wt% Ag₂O/SnO₂ products also showed good property towards the photocatalytic inactivation of S.aureus under visible light irradiation.In addition,it was found photoinduced holes and hydroxyl radicals were the main reactive species for RhB photodegradation.Based on the above results,a possible photocatalytic process of Ag₂O/SnO₂ composite was proposed.2.Ag/AgCl/SnO₂ composite photocatalysts with different mole ratio were synthesized via wet chemical method.The composition and structure of the obtained products were characterized by X-ray powder diffraction?XRD?and scanning electron microscope?SEM?.It was found that Ag/AgCl nanoparticles were dispersed on the surface of SnO₂ nanoplates uniformly.The photocatalytic activity of Ag/AgCl/SnO₂ was evaluated by photodegradation of RhB solution under visible irradiation.2:1 Ag/AgCl/SnO₂ products showed higher photocatalytic activity,and it displayed excellent stability and repeatability because it still showed good photocatalytic property even after 5 photodegradation cycles.In addition,it was found photoinduced holes and hydroxyl radicals were the main reactive species for RhB photodegradation.3.Firstly,flower-like Fe-BiOCl material was prepared.Then Ag/AgCl/Fe-BiOCl composite photocatalysts with different ratio were synthesized via photo-reduction method.The composition and structure of the obtained products were characterized by X-ray powder diffraction?XRD?and scanning electron microscope?SEM?.It was found that the loading of Ag/AgCl nanoparticles didn't change the morphology of Fe-BiOCl photocatalyst.The photocatalytic activity of Ag/AgCl/Fe-BiOCl was evaluated by photodegradation of MB solution under simulated light irradiation.20 wt% Ag/AgCl/Fe-BiOCl products showed higher photocatalytic activity.In addition,it was found electron holes and superoxide anion radicals were the main reactive species for MB photodegradation.