Study On The Preparation,Modification And Enhanced Photocatalytic Activities Of BiOCl

With the development of human society,environmental pollution has become one of the most serious problems that restrict the social sustainable development.Semiconductor photocatalytic technology refers to produce no secondary pollution and an environmental method of dealing with pollution that the semiconductor photocatalyst can degrade the organic pollutants to some small inorganic molecules by using solar energy.Compared with the traditional ways,the photocatalytic technology has much more advantages.As a new type of semiconductor material,Bismuth oxychloride(BiOCl)showed better performance because of its special layered structure,and has attracted wide attention in recent years.However the photocatalytic efficiency of BiOCl is relatively low because of its wide band gap.Thus,it greatly limited its industrial application.In recent years,some studies found that g-C3N4 and BiOI have great photocatalytic activity under visible light.But the application of production is limited,because of its complex preparation process,high cost and low efficiency.In this paper,BiOCl demonstrating excellent ultraviolet-light photodegradation activity was synthesized via the hydrothermal method.And on this basis,prepared g-C3N4/BiOCl and BiOI/BiOCl composites by ultrasonic method and hydrothermal-hydrolytic method,respectively.And study the mechanism that enhance the photocatalytic activity of the BiOCl by hybridizing with g-C3N4 and BiOI.In the paper,first of all,explore the synthesis process of BiOCl by using hydrothermal method.The results show that under the condition of 150℃ and 6 h,the shape of BiOCl was regular nanometer particle.And under the condition of ultraviolet light,the degradation rate of BiOCl into methylene blue was the highest and degradation rate was 79%per hour.Based on this,a series of g-C3N4/BiOCl hybrid photocatalysts with different mass ratios was prepared by ultrasonic method.The results are as follows:After the combination of g-C3N4 with the BiOCl semiconductor,the hybrid photocatalyst exhibited visible photocatalytic activities.The optimal loading amount of g-C3N4 on BiOCl is 60%according to photocatalytic activity and the degradation rate was the highest.The apparent reaction rate constant k value was 0.0139 min-1,it was 1.9 times as that of pure g-C3N4.The mechanism of photocatalytic activity enhancement involved increased separation of electrons and holes between g-C3N4 and BiOCl.The last,a series of BiOI/BiOCl composites was prepared via a hydrothermal-hydrolytic method.The results are as follows:With the addition of BiOI,it can prepare heterojunction,which made the hybrid photocatalyst exhibite visible photocatalytic activities.BiOI/BiOCl hybrid photocatalyst showed the highest photocatalytic activity at ratio for BiOI:BiOCl= 1:1.The apparent reaction rate constant k value was 0.037 min-1,even higher than that of pure BiOI by 2.3-fold.By studying the mechanism,the superior photocatalytic activity of this hybrid photocatalyst is attributed to the low recombination rate of photogenerated electron-hole pairs resulting from the presence of BiOI/BiOCl heterostructure.