Synthesis And Photocatalytic Activity Of Heterojunction ZnO/BiOCl Nanomaterials

ZnO and BiOCl are two kinds of semiconductor photocatalysts with extensive research.They have defects in photoreaction range,high electron-hole pair recombination rate and photo-etching,which lead to unsatisfactory photocatalytic performance of single materials.A common modification method for improving photocatalytic performance.In this paper,BiOCl was modified by ZnO as carrier,and the synthesis method and process conditions of pure ZnO,pure BiOCl and ZnO/BiOCl composite photocatalyst were systematically studied.The unique morphology and structure and high specific surface area were prepared.The photocatalyst was studied and its degradation performance under visible light was studied.The intrinsic mechanism of photocatalytic performance and stability improvement of the composite modified ZnO/BiOCl material was analyzed.The main research contents are as follows:?1?ZnO nanophotocatalysts were prepared by hydrothermal method.The effects of temperature,reaction time and pH on the photocatalytic properties of ZnO were investigated.The crystal structure and morphology of ZnO were characterized.According to the results of XRD analysis,the prepared ZnO material is a hexagonal wurtzite structure with high crystal form.The SEM photo shows that the ZnO photocatalyst prepared by hydrothermal method exhibits a uniform pompon-like structure and interdigitated with a large thickness.It is a30nm nanosheet that provides a large specific surface area for ZnO.The N₂ adsorption characterization results also confirm that the specific surface area of ZnO material is large,and the mesoporous structure exists in the material.Under the conditions of T=180°C,t=22h and pH=11,ZnO has the best photocatalytic performance,and the degradation rate of rhodamine B under ultraviolet light is as high as 99.1%.?2?BiOCl photocatalytic materials were prepared by simple hydrolysis method.The effects of acid concentration and hydrolysis temperature on the photocatalytic properties of BiOCl were investigated.The crystal structure of nano-BiOCl was characterized by XRD and SEM.And the morphology is analyzed.The results of XRD analysis show that the prepared BiOCl exhibits a tetragonal crystal structure with high crystallinity.The SEM results show that the prepared BiOCl consists of nanosheets with a thickness of about 20-25 nm and has a petal-like structure.The photocatalytic degradation experiments show that the BiOCl photocatalyst prepared by this hydrolysis method shows good visible light response.Under the condition of c?CH₃COOH?=0.3mol/L and T=50°C,BiOCl has the best photocatalytic performance,reaching 88.56%.?3?ZnO/BiOCl composite photocatalyst was prepared by hydrolysis method.The XRD characterization results show that the peak shape of the composite is sharpened and the particle size becomes smaller.The SEM image shows that the crystal structure is a flower-like structure with 2D nanosheets on the surface.there is agglomeration,and the surface nanosheets are greatly increased,and the thickness is about 10-20 nm.The photocatalytic performance of the composite ZnO/BiOCl material is better than that of the single ZnO and BiOCl.The Rhodamine B solution is almost completely degraded in the 115min sample under the optimal compounding amount,and the degradation rate of the methyl orange solution in 150 min.When it reaches 88%,the degradation rate of phenol solution is about three times that of pure phase BiOCl.The adsorption performance study confirms that the adsorption of Rhodamine B solution is the strongest,and the performance changes little after repeated use,and it has good stability.By analyzing the internal mechanism,it can be known that the performance improvement of BiOCl photocatalyst after composite ZnO is mainly due to the formation of p-n heterojunction,which causes the band structure to change,the band gap becomes smaller,and the electron-hole pair transfer is promoted.The light response range is broadened,and the visible light degradation effect is improved.