Preparation Of BiOCl-based Heterojunction Photocatalyst And Performance Studies

With the continuous development of industrial technology,environmental pollution and energy crisis are the two most important issues in the world today.In view of these problems,the use of semiconductor photocatalytic technology to degrade organic pollutants under visible light or sunlight has attracted widespread attention.Traditional TiO₂ photocatalyst has been widely used due to its advantages of low price,non-toxicity and high stability.However,since its light response range only exists in the ultraviolet region,this seriously affects the photocatalytic performance.At the same time,the photo-generated electron-hole pairs on the surface of a single semiconductor photocatalyst will quickly recombine,which also greatly hinders the development and application of single semiconductor photocatalyst materials in this field.Therefore,in order to maximize the use of visible light and effectively separate photo-generated electrons and holes,this research topic mainly modifies the dominant crystal plane of the bismuth-based photocatalyst BiOCl and forms a heterojunction with different photocatalysts to develop new and efficient catalyst of light.Moreover,in this study,rhodamine B（RhB）and phenol were selected as the targets for photocatalytic degradation,and various characterization results were used to explore the effect of heterostructures and dominant crystals on the photocatalytic performance of the prepared photocatalysts.The specific research contents are as follows:A series of CdWO₄/BiOCl p-n heterojunction photocatalysts with different molar ratios were successfully synthesized by continuous water heating and hydrothermal methods.The morphology,phase structure,and photoelectric effect of the prepared CdWO₄/BiOCl p-n heterojunction photocatalyst were tested by various characterization methods.At the same time,the organic dye Rhodamine B（RhB）and phenol were degraded under simulated visible light（λ>420nm）to evaluate the catalytic activity of the photocatalyst.The results show that the photocatalytic activity of all CdWO4/BiOCl heterojunctions is better than that of CdWO₄ and BiOCl alone.In addition,25%of the CdWO₄/BiOCl heterojunction compound has the best molar ratio,and RhB can be completely degraded within 15 minutes.During photodegradation,holes（h+）and superoxide radicals（·O₂^-）are the main active species in the photocatalytic process.BiOCl compounds with{001}and{110}exposed crystal faces were synthesized using deionized water and ethylene glycol（EG）as solvents,respectively,and a series of BiOIO₃/{110}BiOCl and BiOIO₃/{001}BiOCl heterojunction photocatalyst.The catalysts were characterized by scanning electron microscope（SEM）,X-ray diffraction（XRD）,and ultraviolet-visible diffuse reflectance spectroscopy（DRS）.The catalytic performance of rhodamine B was evaluated to evaluate the catalytic performance of heterojunction compounds with different crystal planes.The 25%BiOIO₃/{110}BiOCl heterojunction compound exhibited the highest photocatalytic efficiency.In addition,the results of photocurrent experiments show that the BiOIO₃/{110}BiOCl heterojunction can reduce the recombination rate of photogenerated carriers,thereby improving the photocatalytic activity.Finally,holes（h+）and superoxide radicals（·O₂^-）are the main active species.ZnWO₄/BiOCl p-n heterojunction photocatalysts with dominant{110}and{001}crystal planes were synthesized by using ethylene glycol and deionized water as solvents,respectively.Scanning electron microscopy（SEM）,ultraviolet diffuse reflection（DRS）,and X-ray powder diffraction（XRD）were used to characterize the photocatalyst.The photocatalytic activity of ZnWO₄/{110}BiOCl and ZnWO₄/{001}BiOCl heterojunctions was evaluated by degrading rhodamine B（RhB）under visible light irradiation.Higher than ZnWO₄/{001}BiOCl,of which 5%ZnWO₄/{110}BiOCl has the highest photocatalytic activity.In the photocatalytic system,ZnWO₄/{110}BiOCl leads to effective separation and better charge transfer of photogenerated electron and hole pairs,and superoxide radicals（·O₂^-）and holes（h+）are the main photodegradation active substance.A series of PCN/{110}BiOCl and PCN/{001}BiOCl heterojunction composites were prepared by solvothermal loading of porous g-C₃N₄（PCN）with{110}BiOCl and{001}BiOCl,respectively.Scanning electron microscopy（SEM）,X-ray diffraction（XRD）,and ultraviolet-visible diffuse reflection（DRS）were used to characterize the prepared samples.The photocatalytic activity of rhodamine B was evaluated by its degradation under visible light.The results show that the heterojunction composite has higher photocatalytic activity than the compound alone,and the 1:1 PCN/{110}BiOCl nanocomposite has the best rate constant.The improvement of photocatalytic performance is due to the formation of the PCN/{110}BiOCl heterojunction interface,and its existence is considered to be a favorable factor for the separation and migration of photogenerated carriers.In addition,active species capture experiments show that holes（h+）are the main active species in photocatalytic processes.