【作者】 王芸；

【导师】 谢长生；

【作者基本信息】 华中科技大学 ， 材料学， 2011， 博士

【摘要】 电化学阻抗谱是一种准稳态的测试方法,与其他常规的电化学方法相比它能够得到更多的动力学信息及界面结构的信息,因而被广泛应用在材料研究方面。复合材料是由经过选择的、含有一定数量比的两种或两种以上的组分,通过人工复合组成多相、三维结合且各相之间有明显界面的、具有特殊性能的材料。复合材料的结构与性能之间密切相关。Cu/LDPE复合材料和ZnO/WO3纳米复合材料都属于复合材料。其中Cu/LDPE复合材料属于金属/聚合物复合材料,它是一种新型载铜IUD材料,能够克服传统Cu-IUD的一些缺点。ZnO/WO3纳米复合材料属于纳米功能复合材料,在光催化材料中应用较广为了研究Cu/LDPE复合材料中的界面性能与复合材料中铜离子的释放性能之间的关系,对Cu/LDPE复合材料进行了电化学阻抗谱测试和释放性能的测试,并提出了纯LDPE材料的微结构特征模型和Cu/LDPE复合材料在不同阶段的微结构特征模型及相应的等效电路模型。对Cu/LDPE复合材料的电化学阻抗谱和铜离子释放性能的研究结果表明,随着铜含量的增加,复合材料中聚乙烯与溶液之间的界面增加,界面电阻Rint随之增大,界面电容Cint随之减小,铜离子的释放速率也增大。相同铜含量的微米复合材料和纳米复合材料相比,微米复合材料中溶液与聚乙烯之间的界面电阻Rint较大,界面电容而Cint较小。当复合材料中铜含量较高时,微米复合材料的铜离子的释放速率大于纳米复合材料的铜离子的释放速率铜含量为25wt.%的纳米复合材料浸泡在溶液A(纯水)、溶液B(含氯正盐)、溶液C(溶液B基础上添加NaHCO3)、溶液D(溶液C基础上添加NaH2PO4)、溶液E (溶液D基础上添加葡萄糖葡萄糖)中,LDPE和溶液之间的界面电阻的变化为Rint(A)[Rint(B)、Rint(C)、Rint(D)]<Rint(E), Cint(A)[Cint(B)、Cint(C)、Cint(D)]>Cint(E),扩散阻抗的变化为Zw(B)<Zw(E)<Zw(D)<Zw(C)<Zw(A),铜离子的释放速率变化为r(A)< r(C)<r(D)<r(B)<r(E)。铜含量为25wt.%的纳米复合材料在含蛋白质的溶液中的扩散阻抗(Zw)首先随着蛋白质浓度的增加而降低直至蛋白质浓度达到2g/L,然后扩散阻抗随着蛋白质浓度的增加而增加。随着蛋白质浓度的增加,复合材料中铜颗粒的表面覆盖的蛋白质增多。当蛋白质浓度较低时,铜离子的释放速率比不含蛋白质的模拟宫腔液的大。当蛋白质浓度增加时,蛋白质在铜颗粒表面的覆盖率增加,铜离子的释放速率降低。对铜含量为25wt.%的纳米复合材料浸泡不同时间的电化学阻抗谱进行拟合得到扩散阻抗与时间的关系。结果表明扩散阻抗随着时间的增加而降低直至达到稳定。复合材料在NaCl溶液中的铜离子的释放速率在浸泡初期较大,然后下降至平稳。为了研究ZnO/WO3复合材料中的界面性能与ZnO/WO3复合材料光催化性能之间的关系,对ZnO/WO3复合材料进行了光电催化测试和电化学阻抗谱测试,并对复合材料进行了XRD、SEM、HR-TEM和UV-vis表征。实验结果表明ZnO/WO3复合材料在WO3含量为40-50wt.%时的光电催化性能最好,对光的响应最小。XRD和高分辨透射电镜的结果表明ZnO/WO3复合材料中生成了ZnWO4,形成了ZnO/ZnWO4/WO3双异质结。双异质结的存在影响着材料的光电催化性能和对光的响应。结合ZnO/ZnWO4/WO3复合材料的结构,给出了纯ZnO、ZnO/ZnWO4/WO3复合材料和纯WO3的等效电路图。由电化学阻抗谱拟合得到的数据可知,复合材料中颗粒与溶液之间的界面电阻(Rint-1)和界面电容(Cint-1)以及颗粒和颗粒之间的界面电阻(Rint-2)和界面电容(Cint-2)与复合材料中颗粒的含量、异质结的多少有关。利用电化学阻抗谱和紫外可见漫反射吸收光谱获得了ZnO/ZnWO4/WO3复合材料的能带结构。结果表明WO3含量为50wt.%时的ZnO/WO3复合材料的价带位置最正,这使WO3含量为50wt.%时的ZnO/WO3复合材料中有较多的具有强氧化能力的空穴和羟基自由基产生,使目标物质甲基橙能最大程度地有效降解,WO3含量为50wt.%时的ZnO/WO3复合材料具有较高的催化能力。更多还原

【Abstract】 The electrochemical impedance spectroscopy is a quasi-steady-state method. It can give more dynamic informations and interface structure informations that other conventional electrochemical methods can not give. Therefore, it is widely used in the materials researches.The composites are the materials that composed of more than two components with a certin amount which are selected. The composites are the artificial compounds with multiphases, three-dimensional integration, clear interface between each phase, and the special properties. The relationship between the structures and properties of composites is close.Cu/LDPE composites and ZnO/WO3 nanocomposites both belong to the composites. Cu/LDPE composites are metal/polymer composites. It is a novel Cu-IUD material that can overcome the shortcomings of traditional Cu-IUDs. ZnO/WO3 nanocomposites belong to the nano functional composites.They are widely used as photocatalytic materials.In order to investigate the relationship between the interface property and the Cu2+ release property of Cu/LDPE composite, the electrochemical impedance spectroscopy was used to obtain the interface property. The microstructure characteristics and the equivalent circuit of pure LDPE and Cu/LDPE composites that immersed in the solutions for different periods were presented.The electrochemical impedance spectroscopy and Cu2+release results showed that with the increasing of the content of copper particles in the composites the interface between polyethylene and the solution increased. That resulted in the interface resistance {Rint) increasing and the interface capacitance (Cint) decreasing. The release rate of cupric ions increased with the increasing of the interface. The interface between polyethylene and the solution in the microcomposites was more than that in the nanocomposites with the same copper content. The interface resistance in the microcomposites was larger and the interface capacitance in the microcomposites was smaller than that in the nanocompsoites. When the concentration of copper particles in the composite was high, the release rate of cupric ions in the microcomposite was larger than that in the nanocomposite.When the nanocomposite with 25 wt.% copper nanoparticles immsered in Solution A (pure water), Solution B (containing normal salts with CI-), Solution C(containing B and NaHCO3), Solution D (containing C and NaH2PO4), and Solution E (containing D and glucose), the change of the interface resistance (Rint) and the interface capacitance (Cint) between LDPE and the solution in the solutions were that Rint(A)[Rint(B)、Rint(C)、Rint(D)]<Rint(E) and Cint(A)[Cint(B)、Cint(C). Cint(D)]>Cint(E). The order of the diffusion impedance in the solutions was that Zw(B)<Zw(E)<Zw(D)<Zw(C)<Zw(A). The order of the release rate of cupric ions in these five solutions was r(A)< r(C)< r(D)< r(B)< r(E).When the nanocomposite with 25 wt.% copper nanoparticles immersed in the simulated uterine solutions with 0.5 g/L,1 g/L,2 g/L,4 g/L,6 g/L and 8 g/L, respectively, the diffusion impedance first reduced with the increasing of the concentration of protein until the concentration of protein reached 2 g/L. Then the diffusion impedance increased with the increasing of the concentration of protein. Along with the increasing of the concentration of protein, the protein that covering the copper particles increased. When the concentration of protein was low, the protein accelerated the Cu2+release rate. When the protein concentration increased, the rate of coverage of protein increased that preventing the release of cupric ions.Based on the fitting results of the electrochemical impedance spectroscopy of the nanocomposite with 25 wt.% copper nanoparticles that immersed in the solution for different days, the diffusion impedance decreased with the increasing time until the diffusion impedance reached a platform. The release rates of cupric ions was very large in the early period, then the release rates of cupric ions became small and the change of the release rates of cupric ions was steady.In order to investigate the relationship between the interface property and the photocatalytic property of ZnO/WO3 nanocomposite, the photoelectrocatalytic efficiency and the electrochemical impedance spectroscopy of ZnO/WO3 nanocomposite were obtained. The results showed that the composites with 40-50 wt.% WO3 had the higher photoelectrocatalytic efficiency. With the results of XRD and HR-TEM, it was found that ZnWO4 phase was formed in the composites.The existence of ZnWO4 introduced a type of ZnO/ZnWO4/WO3 double heteroj unctions into the composites, which gave the contribution to the photocatalytic property and the response to the light.The equivalent circuit of pure ZnO, ZnO/WO3 nanocomposite and pure WO3 were presented. The results of the electrochemical impedance spectroscopy showed that the interface resistance (Rint) and the interface capacitance (Cint) were related to the amount of the grains and the heteroj unctions in the composites.The energy band structures of ZnO/WO3 composites were obtained using the electrochemical impedance spectroscopy and UV-vis diffuse reflection absorption spectroscopy. When the amount of WO3 was 50 wt.%, the valence band was the most positive.That resulted in the more holes and hydroxyl radical with strong oxidation ability producing. Therefore, the methyl organge could degrade effectively.更多还原