Preparation And Properties Of Zinc Doped Bismuth Vanadate And Bi₂s₃-c Heterojunction Photocatalysts

The problem of environmental pollution brought by the rapid development of the economy has become one of the problems that people are eager to solve in the blue sea and blue sky.Semiconductor photocatalysts have gradually become a research hotspot for scientists because of their advantages in the treatment of organic polluted wastewater.Among them,bismuth-based semiconductor visible light catalytic materials such as BiVO₄ have broad application prospects in the field due to narrow band gap and corrosion resistance,but the disadvantages of low photoelectron and hole separation efficiency limit the application of these photocatalytic materials.Therefore,the bismuth-based photocatalyst is modified to inhibit the photo-generated carrier recombination and improve its catalytic activity.Oxides,sulfides and salts of bismuth-based photocatalytic materials are good photocatalysts,but due to the shortcomings of Bi₂S₃,such as low photocatalytic performance.Therefore,after the doping modification of BiVO₄,we modified the other bismuth-based photocatalyst Bi₂S₃.Firstly,a single BiVO₄ and Zn doped BiVO₄ photocatalytic material was prepared by hydrothermal method.The structure and properties of the products were characterized by XRD,SEM,UV-vis DRS,PL and XPS,etc.The photocatalytic activity of the as-prepared samples was studied by using xenon lamp as the light source and Rhodamine B?RhB?as the simulated pollutant.The results show that the degradation of RhB by single BiVO₄ is poor after 120 min of light irradiation,However,the sample with a doping amount of 2.5%Zn/BiVO₄ catalyzed the photodegradation performance of RhB,when the simulated sunlight was irradiated for 90 min,the degradation rate of RhB was 96%.Experiments by capture of active free radicals revealed that the main active species of photocatalytic degradation of rhodamine B by Zn-doped BiVO₄ is·O₂^-.The photocatalytic performance of 2.5%Zn/BiVO₄ is improved due to doping to change BiVO₄ from a single crystal form to a mixed crystal form,and a heterojunction is formed between different crystal forms of the same substance,prompting the rapid separation of photogenerated carriers.The metal organic framework?MOF?is used as the precursor to obtain Bi₂S₃-Bi and Bi₂S₃-C materials after calcining the precursor in a tube furnace,the photocatalytic efficiency of methylene blue?MB?catalyzed by the prepared materials under light irradiation was studied.The photocatalytic test results showed that the degradation rates of Bi₂S₃-Bi and Bi₂S₃-C samples on methylene blue were 70%and 95.7%,respectively,within 120 min.The photoelectric properties of the products were investigated.The transient photocurrent test results showed that the photogenerated current increased significantly under the illumination of simulated sunlight.The AC impedance test shows that the impedance is reduced under the illumination of light,that is,the charge recombination can be suppressed under illumination.Thus,the prepared photocatalytic material has good photoelectric properties.