| The rapid development of industrial and agricultural production have led to a sharp increase in population,which has brought a series of environmental problems.Among them,compared with other pollution,water pollution has more extensive and serious damage to environment.As a new technology that relies on sunlight as the driving force,photocatalytic technology has high development potential in water pollution control due to its mild reaction conditions,no secondary pollution,recyclability and strong redox ability.In this paper,different properties of bismuth oxy iodide were prepared by adjusting the content of iodine.And it was modified by ion-doping to synthesize Nidoped Bi4O5I2 and La/Sm co-doped Bi5O7I.The physicochemical properties of the synthesized photocatalysts were studied by various characterization methods,such as XRD,XPS,SEM,TEM,UV-Vis and PL.Tetracycline(TC)and rhodamine B(RhB)were used as target pollutants to investigated the photocatalytic activity of the prepared photocatalysts.Finally,the possible photocatalytic reaction mechanism was analyzed by the characterization and experimental results.Details as follows:1.The ethylene glycol was used as a solvent,and Bi(NO3)3·5H2O and KI were added to synthesize bismuth oxyiodide.Different proportions of Ni(NO3)3·5H2O was added to the reaction system before solvothermal,and different mass ratios of Ni-doped Bi4O5I2 were synthesized.Its structural composition and photoelectrochemical properties were explored by some characterization methods.Its photocatalytic activity was studied by degradation of TC under visible light irradiation.The results showed that the 5 wt%Ni-doped Bi4O5I2 showed the best photocatalytic efficiency among the samples with the TC degradation rate of 91%.The trapping experiment showed that the active free radical ·O2-played an important role in degradation of TC.The final results showed that Ni-doping improved the charge separation efficiency and specific surface area of the material.Besides,Ni-doping formed an electron trap on the surface of Bi4O5I2,which trapped electrons,promoted the separation of carriers and improved the photocatalytic performance.2.Bi(NO3)3·5H2O was used as bismuth source and KI as iodine source.Threedimensional nanoflower-shaped Bi5O7I was synthesized by solvothermal method and calcination method.A series of La/Sm co-doped Bi5O7I were synthesized by adding different proportions of lanthanum nitrate and samarium nitrate before solvothermal.TC and RhB were used as target pollutants to investigate their photocatalytic activity,the results showed that the photocatalytic performance of La/Sm co-doped Bi5O7I was significantly improved,which may be because the doping of La and Sm expanded the light absorption range of Bi5O7I.In addition,the surface defects created by ion-doping promoted the separation of electrons and holes.The trapping experiment and ESR proved that the ·O2-,1O2 and h+played roles in the process of degradation of pollutant.On this basis,the possible degradation mechanism was proposed.Finally,LC-MS and analyzing software were used to analyze the possible degradation pathway of TC and the toxicity of intermediate products.The results showed that the toxicity of the intermediate products was lower than TC,which meant the reduced water pollution.The results showed that a new type of bismuth oxyiodide photocatalyst was designed and synthesized by ion-doping which effectively improved the photocatalytic performance of bismuth oxyiodide.This study provided a certain theoretical research basis for the doping research of bismuth-based photocatalytic materials,and provided a scientific basis for the subsequent research and application. |
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