Research On Preparation And Bactericidal Performance Of BiVO₄ Quantum Dots Composites

The outbreak of the novel coronavirus in early January 2020 was not only a public health crisis,but also caused serious economic losses to our country.In this"war on COVID-19",disinfection products have become an essential and urgent need in the country with a population of 1.4 billion.Therefore,the development of new green sterilization materials can not only solve the problem of people’s livelihood,but also"normalize"epidemic prevention.In this paper,the green and environmentally friendly bismuth vanadate（Bi VO₄）quantum dots with excellent visible light response are used as the basic materials for photocatalytic sterilization.Three kinds of Bi VO₄ quantum dots were synthesized using different experimental methods.The intrinsic photocatalytic activity of Bi VO₄ semiconductor materials with quantum size was synthesized.Bi VO₄ and Bi OI quantum dots are combined to form a heterojunction material,which further improves the photocatalytic sterilization performance.In addition,MOFs precursors were prepared by utilizing the large specific surface area and pore diversity of MOFs,and their photocatalytic decontamination activity was studied,which was then combined with Bi VO₄semiconductor materials as preparation for the next stage.Finally,we try to choose excellent Bi VO₄-3 and 2MZMs to compound,which is expected to form a multifunctional photocatalytic sterilization and decontamination material.Specific research contents are as follows:1.Three kinds of Bi VO₄ semiconductor（Bi VO₄-1,Bi VO₄-2 and Bi VO₄-3）photocatalysts with quantum size of about 6 nm were prepared in oil bath at 120℃,modified by EDTA and hydrothermal method at 120℃.The bactericidal experiment of E.coli was carried out by spraying method under visible light.The results showed that Bi VO₄-3 could kill all E.coli with 10μL concentration of 1–5×10⁸ CFU/m L at 120 min,but the photocatalytic bactericidal activities of Bi VO₄-1 and Bi VO₄-2 were not high under the same conditions.2.In order to further improve the photocatalytic sterilization activity of Bi VO₄quantum dots,three Bi OI/Bi VO₄ heterojunction materials（BBV1,BBV2 and BBV3,respectively）were formed by combining Bi VO₄ quantum dots with Bi OI semiconductor photocatalysts with quantum sizes of about 3 nm.Bi OI quantum dots and BBV were used to sterilize E.coli and S.aureus under visible light.It was found that all the three BBVs killed E.coli with 10μL concentration of 1–5×10⁸ CFU/m L at 120 min,and all the BBV2and BBV3 killed S.aureus with 5μL concentration of 1–5×10⁸ CFU/m L at 120 min.Bi OI quantum dots killed 10μL E.coli and 5μL S.aureus at 1–5×10⁸ CFU/m L at 180 min.It can be seen that the combination of Bi OI and Bi VO₄ can improve the photocatalytic bactericidal activity of Bi VO₄ and Bi OI.3.In order to prepare multifunctional photocatalytic sterilization and decontamination composites,by preparing precursors with different Mo:Zr feeding ratios n Mo/Zr-MOFs（n MZMS,n=1,2,3,4）precursors,the decontamination activity test of methylene blue（MB）and Cr⁶⁺under visible light showed that 2MZMs had the best photocatalytic performance:the degradation rate of MB was 94.36%in 120 minutes of visible light irradiation,and the reduction rate of Cr⁶⁺in 100 minutes was 91.20%.MOFs precursors were screened for the next stage of combination with bismuth-based semiconductor materials to form multifunctional bactericidal decontamination multifunctional photocatalyst.Finally,Bi VO₄-3 quantum dot material with excellent bactericidal performance and 2MZMs precursor with excellent decontamination performance were used to synthesize2MZMs/Bi VO₄ nanomaterials by two-step hydrothermal method.The bactericidal and degradation activities of the 2MZMs/Bi VO₄ nanomaterials against E.coli and MB were found in the killing and degradation experiments under visible light.The results provide a basis for the future development of multifunctional photocatalytic materials.4.The bactericidal and decontamination active substances of the above materials were analyzed by ESR test.It was found that·O₂^–and·OH were the main active substances in the sterilization experiment,and·O₂^–and·OH were the main active substances in the degradation of MB and reduction of Cr⁶⁺.