Synthesis And Photocatalytic Properties Of Bi₂O₂CO₃/?-Bi₂O₃/Ag₂O Nanocomposites

With the development of the economy and society,the use of fossil fuels such as coal and petroleum has aroused serious environmental pollution and energy shortages.People desires clean energy such as hydrogen,wind,and solar energy.Photocatalytic materials are considered to be a new energy shortage solution due to their environmental friendliness and potential environmental treatment capacity and photolysis water hydrogen production capacity.The bismuth-based compound semiconductor has special physical properties and chemical properties because of its special layered structure and has been extensively studied.It is considered to be an ideal photocatalytic material.As a bismuth compound semiconductor,Bi₂O₂CO₃ has an Aurillius phase oxide layered structure,that is,(CO₃)^2-atomic layer and(Bi₂O₂)²⁺atomic layer arranged alternately.There is a strong built-in electric field between the(Bi₂O₂)²⁺atomic layer and the(CO₃)^2-atomic layer,which can effectively promote the separation and transfer of photogenerated carriers.Therefore,it has potential application prospect of semiconductor photocatalysis.In this essay,Bi₂O₂CO₃ semiconductor photocatalyst is prepared by a composite-salt mediated approach firstly.However,due to its large band gap,the catalytic performance in the ultraviolet-visible range is not ideal.Therefore,we used a simple chemical deposition method to deposit Ag₂O with visible light absorption on its surface,and studied the efficiency of photocatalytic degradation of methylene blue by both.Although the photocatalytic performance is improved by depositing Ag₂O,the ability of photocatalytic degradation of MB is still not outstanding.Therefore,we constructs Bi₂O₂CO₃/?-Bi₂O₃heterojunction,and then selects Ag₂O nanoparticles to be load on its surface,which effectively improves its photocatalytic ability to degrade methylene blue.In this process,the temperature of the composite salt is adjusted to obtain a Bi₂O₂CO₃/?-Bi₂O₃heterojunction,and then Ag₂O is deposited on the surface of the heterojunction to obtain a Bi₂O₂CO₃/?-Bi₂O₃/Ag₂O(BBA)composite photocatalyst with different mass ratios.The photocatalytic properties and influencing factors are discussed in detail.The specific research work is as follows:Bi₂O₂CO₃ nanosheets are obtained by a composite-salt mediated approach,and silver oxide is deposited on the surface.The composition,morphology and structure of the samples are characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The photocatalytic degradation of methylene blue(MB)by Bi₂O₂CO₃ and Bi₂O₂CO₃/Ag₂O under simulated sunlight is further studied.We find that compared with the single Bi₂O₂CO₃,the photocatalytic degradation performance is greatly improved after depositing silver oxide,and the MB solution with a concentration of 2*10^-5M can be completely degraded within 45 minutes.Bi₂O₂CO₃/?-Bi₂O₃(BB)nanosheets are obtained by a composite-salt mediated approach by controlling the temperature of the reaction process,and Ag₂O are deposited on the surface of the material by chemical deposition to obtain Bi₂O₂CO₃/?-Bi₂O₃/Ag₂O.The morphology,composition,structure,optical performance and electrochemical performance of the material are characterized by means of SEM,XRD,TEM,AFM,XPS,UV-vis reflection spectrum,PL spectrum,EIS impedance test and photocurrent test.The degradation performance of BB and BBA with different mass ratios on methylene blue(MB)solution under simulated sunlight are studied.We find that Bi₂O₂CO₃/?-Bi₂O₃/Ag₂O showed superior photocatalytic degradation performance compared to single Bi₂O₂CO₃/?-Bi₂O₃.Among them,when the content of Ag NO₃ is 33.3mt%,the composite photocatalyst Bi₂O₂CO₃/?-Bi₂O₃/Ag₂O(BBA-3)has the best photocatalytic degradation performance,and can completely degrade the MB solution with a concentration of 2*10^-5M within 15 minutes.After several MB degradation cycles with the same BBA-3 sample,we find that its structure and performance remains.Finally,the mechanism of photocatalytic degradation of MB in BBA samples is analyzed in details...