Preparation And Properties Of BiOCl Photocatalytic Composite Materials

In recent years,with the increasing shortage of resources and energy,the environment on which human beings depend for survival is also deteriorating.In order to change this situation,people from all walks of life have put forward many reasonable and effective strategies.Since the phenomenon that titanium dioxide can be used as electrode to decompose aquatic hydrogen is found,scientists have paid more attention to photocatalytic technology year by year.Photocatalytic technology can make better use of solar energy,so this technology has become an effective way for mankind to solve current problems.Semiconductor photocatalytic materials generally include the following categories:（1）Bi-based photocatalytic materials such as BiOCl,Bi2 MoO₆ and Bi₂WO₆;（2）perovskite photocatalytic materials such as Na Ta O3,La2Ti2O7 and La Fe O3;（3）Ag-based photocatalytic materials such as Ag₃PO₄,Ag SeO₄ and Ag Br;（4）metal oxide photocatalytic materials such as WO₃,TiO₂ and Zn O;（5）Photocatalytic materials of metal oxides such as Cd S,WS2 and Mo S2.This paper mainly expounds the principle of semiconductor photocatalysis,the application of photocatalysis technology,the influence of photocatalysis performance and the enhancement strategy.In addition,the exploration and research on improving the photocatalytic performance of bismuth oxychloride were carried out in three aspects.The specific work is as follows:（1）BiOCl with（010）main exposed surface was prepared by adding sodium persulfate to bismuth nitrate pentahydrate and potassium chloride as raw materials.The photocatalytic performance of rhodamine B solution was characterized by degradation.The results show that the BiOCl prepared by adding sodium persulfate has better photocatalytic performance than the BiOCl prepared without adding sodium persulfate.After three cycle tests,the samples still showed good catalytic performance.（2）A series of metal Cr-doped BiOCl photocatalysts were successfully prepared by one-step hydrothermal method by adding different amounts of Cr（NO₃）3-9H2O into the precursors of traditional preparation of BiOCl photocatalysts.X-ray diffraction（XRD）and scanning electron microscope（SEM）were used to characterize the synthesized samples.Rhodamine B solution was used as degradation system to characterize the photocatalytic performance.The experimental results show that the catalytic performance of BiOCl doped with Cr metal is better than that of the samples without Cr metal.Among them,BOC-Cr 20 has the best photocatalytic performance.（3）the BiOCl/Sn₃O₄ composite photocatalyst was successfully synthesized by one-step hydrothermal method with bismuth nitrate pentahydrate as bismuth source,stannous chloride as tin source,potassium chloride as chlorine source and water as solvent.The photocatalytic performance of the composite was characterized by using methyl orange solution as the degradation product under visible light.The experimental results show that the degradation efficiency of BiOCl/Sn₃O₄ heterojunction photocatalyst is better than that of BiOCl and Sn₃O₄ alone.The heterojunction between BiOCl and Sn₃O₄ can effectively promote the separation of photogenerated electrons and holes,thus effectively enhancing the photocatalytic activity of the composite.The photocatalytic efficiency of BiOCl/Sn₃O₄ did not decrease significantly after the photocatalyst was recycled for three times.