Doping And Modification Of BiOX(X=Cl,Br) Layered Materials And Study On Photocatalytic Performance

Semiconductor photocatalysis technology has opened up a new way for us to deal with environmental pollution and energy shortage.Photocatalytic technology has the advantages of controllable cost,pollution-free,recycling the renewable solar energy in nature and so on.How to find a photocatalyst with high efficiency is the most important key problem.As a kind of ternary semiconductor material,bismuth based semiconductor（BIOX）has unique layered crystal structure and appropriate band gap.It has excellent and stable photocatalytic performance,which has been widely studied.In order to further enhance the photocatalytic activity under the visible light.On one hand,it is necessary to expand the spectral absorption range.On the other hand,it is necessary to improve the photon utilization rate.Herein,we modified BiOX by doping element and introduced defect energy levels to expand the visible light absorption range.At the same time,we used the increased conductivity of semiconductor after doping to promote the effective separation of photo-generated electron hole pairs,thereby enhancing their photocatalytic activity.In this thesis,Ag and Cu were introduced into the self-assembled nano-spherical BiOBr respectively,to studied the effect of metal ion doping on the photocatalytic performance of BiOBr.On the basis of exploring the influence of metal element doping on the photocatalytic performance of BiOBr.We also did non-metallic element C doping on the prepared BiOBr,the temperature and the C content are adjusted to adjust the energy band structure of the BiOBr during the doping process to broaden the light response range,and further improve the photocatalytic performance of BiOBr.Finally,the modification of BiOCl by halogen elements was discussed.The Ag-doped BiOCl was prepared by photoreduction.The effect of hydrolysis temperature on the form of Ag in BiOCl and its photocatalytic activity were studied.Conclusion as below:（1）Ag ion doped into the BiOBr crystal,and the three-phase Ag/Ag Br/BiOBr was successfully constructed.The doping content of Ag has a great influence on the form of Ag in the photocatalyst,so as to realize the microstructure control of the three-phase catalyst,which has an important influence on its photocatalytic performance.The Ag-doped BiOBr sample showed excellent photocatalytic activity.Under 120minutes of visible light irradiation,the rate of photocatalytic degradation of rhodamine B was 10 times than that of BiOBr.The improvement of photocatalytic performance is mainly attributed to the plasma effect of Ag and the effective transfer of photon-generated electrons by Ag nanoparticles.（2）Doping Cu in BiOBr,the introduced of Cu changed the microscopic morphology of BiOBr from regular nanospheres to irregular clusters,providing more surface active sites.Cu doping effectively regulates its energy band structure,as an electron acceptor enhances the separation and transmission efficiency of photo-generated carriers.When the amount of Cu doped is less than 3%,the intensity of photocurrent increases accordingly.When the amount of Cu doped is more than 3%,the intensity of photocurrent decreases accordingly.After Cu doping,the photocatalytic activity of the sample was significantly improved.The rate of visible light degradation of rhodamine B increased from 4.69×10-3min^-1to 54.73×10-3min^-1.（3）Firstly,we prepared BiOBr.On this basis,we did carbon doping in BiOBr lattice.C-doping effectively expands the visible light response range of BiOBr and regulates the energy band structure.The improvement of photocatalytic performance caused by C doping is due to the change of lattice structure caused by the bonding of C and O after C doping,which leads to the regulation of the energy band structure.At a temperature of160 ^oC,the C-doping ratio of 7:5 showed the most excellent photocatalytic performance.（4）Ag loaded BiOCl nano tablets,we find Ag ion was not reduced to Ag under light,but existed in the form of Ag Cl.To some extent,the construction of Ag Cl/BiOCl heterojunction enhances the visible light response of BiOCl,reduces the band gap,facilitates the separation and transmission of photogenerated electron hole pairs,and improves its photocatalytic activity...