Preparation Of Bismuth-based Oxide Nanomaterials And Their Photocatalytic Properties

With the excessive exploitation of natural resoures and grave pollution of environment,the deterioration of mankind living environment has become more and more serious.As one the novel treatment method,photocatalysis gains more and more attentions in the field of environmental clean up.The preparation of photocatalysts with high photocatalyst properties is most important in photocatalysis techonology. An ideal photocatalyst should be stable,inexpensive,non-toxic,and highly photoactive and good visible light absorptive.TiO₂ is known as one of the most effective photocatalysts for the degradation of organic pollutants,and its photocatalytic behavior has been studied extensively.Although titanium oxide catalysts are capable of decomposing a wide variety of organic pollutants and toxic materials,in both liquid and gas-phase systems,yet their reactivity and selectivity are not enough for large scale applications.On the other hand,because of the size of its band gap,TiO₂ is effective only under ultraviolet irradistion.In recent years,many research groups have focused on binary metal oxides with different crystal structure to find a more effective photocatalyst by increasing the efficency of charge separation and extending the photo-responsing range.In this dissertation,we prepared the bismuth-radicle nano-structural oxides and examined their photocatalytic preoperties.This dissertation mainly includes:The source sample Bi₂WO₆ was prepared by a chemical solution decomposition method.XRD patterns indicated that Bi₂WO₆ with good crystallinity can be obtained by annealing at 500℃.As the temperature increases,the cryatallinity of the sample has not improved significantly.After a suitable acid treatment,the source samople have been pure phase,nano-structural Bi₂WO₆.UV-Vis showed that both samples before and after the acidification are response to visible light.Photocatalytic properties of the powders were evaluated using the dye Rhodamine B as a model organic compound under the visible light irradiation in aqueous solution of the suspension system.It was found that samples have good performance of photocatalytic degradation.After the acid treatment,nano-layered film Bi₂WO₆ samples have more excellent photocatalytic activity than the source samples.It is also found that the temperature has a certain influence to the photocatalytic reaction. Solution changes of the absorption spectra show that in the photocatalytic degradation of Rhodamine B,the four hexyl has been gradually taking off.The source sample Bi₁₄W₂O₂₇was prepared by a chemical solution decomposition method.XRD patterns indicated that Bi₁₄W₂O₂₇with a little impurity can be obtained by annealing at 500℃.As the temperature increases,the cryatallinity of the sample has not improved significantly.After a suitable acid treatment,the source samople have been pure phase,nano-structural Bi₁₄W₂O₂₇,Bi₂WO₆ and tungstenic acid.UV-Vis showed that both samples before and after the acidification are response to visible light.Photocatalytic properties of the powders were evaluated using the dye Rhodamine B as a model organic compound under the visible light irradiation in aqueous solution of the suspension system.It was found that samples have good performance of photocatalytic degradation.After the acid treatment, nano-layered film samples have more excellent photocatalytic activity than the source samples.Solution changes of the absorption spectra show that in the photocatalytic degradation of Rhodamine B,the four hexyl has been gradually taking off.The sample Bi₇Ti₄NbO₂₁was prepared by a chemical solution decomposition method.XRD patterns indicated that Bi₇Ti₄NbO₂₁with a little impurity can be obtained by annealing at 500℃.As the temperature increased to 550℃,the cryatallinity of the sample has improved significantly.After a suitable acid treatment, the source samople have been pure phase Bi₂Ti₂O₇.Photocatalytic properties of the powders were evaluated using the dye methyl orange as a model organic compound under the UV light irradiation in aqueous solution of the suspension system.It was found that samples have good performance of photocatalytic degradation.Large single crystal sheet ofα-MoO₃ was synthesized by a novel acidification of ammonium heptamolybdate tetrahydrate chemical process.TheⅠ-Ⅴcurves along the growth direction have been investigated.The resistivity of the sample along the [001]direction has also been calculated.The UV-Vis DRS have been analysed,and the energy band gap has been calculated.