【作者】 葛介超；

【导师】 唐波；

【作者基本信息】 山东师范大学 ， 物理化学， 2008， 博士

【摘要】 纳米结构材料常具有许多传统材料所不具备的光、电、磁和化学性质,在磁记录、电子元件、生物医学、传感器以及工业催化等诸多重要技术领域有着广泛的应用前景,而成为当今材料研究的热点之一。本论文正是在这一研究背景下,致力于设计和构筑新的自组装纳米结构,并对他们的结构和性质进行详细的研究,同时利用多种实验技术实现了对体系中功能纳米单元的尺寸、形貌、组成和结构的控制,为构建基于这些功能纳米单元的纳米器件提供了相关实验方法与理论基础。本论文采用了改进的水热/溶剂热和多元醇介导合成方法制备了具有多维形貌与结构的氧化物,并对他们的性质和应用进行了详细的研究。其主要内容如下:一、我们在水热反应的条件下,利用CTA⁺和Zn（OH）₄^2-的自组装,合成了具有剑麻状的三维ZnO新型纳米结构,表面活性剂CTAB的浓度以及Zn²⁺/OH^-的摩尔比是形成分散性好的高纯度的ZnO纳米结构的主要因素。合成方法简单快速,产量高,而且反应温度区域大。根据考察不同CTAB浓度、Zn²⁺/OH^-的摩尔比和不同反应时间和反应温度的影响,提出了生成这种纳米结构的机理。最终产物用XRD,SEM,TEM,HRTEM,SAED,和PL技术进行表征和测试。这种剑麻状的三维ZnO纳米结构不仅可以作为制作功能纳米或微米器件的理想材料,而且其合成方法同样可以应用到其他两性氧化物如氧化铝纳米结构的合成。二、采用异辛醇为还原剂,通过表面活性剂辅助的水热反应合成了新的一维层状MnO₂组装结构,这种组装结构含有少量的γ-Mn₂O₃杂质。XRD,SEM,TEM,HRTEM,和XPS对样品进行了表征,用超导量子磁强计（SQUID）测试了样品的磁性。实验结果表明异辛醇,聚乙二醇400,氢氧化钾的浓度和反应时间是影响纳米线束生长的重要因素。这种纳米组装结构的生长机理也被详细研究。超导量子磁强计测试表明样品在32K以下显示典型的铁磁性质,而在32K以上则显示顺磁行为。这种性质使得样品可以作为磁性纳米器件的理想材料。本合成方法不仅适用于合成各种氧化物纳米材料,而且还可以扩展到金属或合金一维纳米结构的制备或组装。三、采用了简单的一步反应法制备了由3-5nm的CeO₂纳米粒子组装而成的中孔纳米球组装结构。该纳米结构产量高,分散性好,尺寸分布均匀。利用TEM,SEM,FTIR,XRD等技术观察了产物的形貌、考察了产物的生长过程,提出了产物由二维的圆盘状生长为零维的具有中孔结构的纳米球生长机理。这种中孔结构CeO₂纳米球组装结构及其负载金纳米粒子后的混合体系不仅对CO的催化氧化显示了优越的性能,而且还可能应用到诸如生物化学等其他重要领域。四、将纳米中孔CeO₂粒子用作过氧化物酶模拟酶,考察了pH、温度和H2O₂浓度和反应时间对其催化氧化活性的影响,得到了显示其最高催化活性的最佳条件。并在最佳条件下,将其用于模拟过氧化物酶来检测H₂O₂的浓度,结果表明这种有3-5nm组装而成的CeO₂纳米粒子作为过氧化物酶模拟酶有着较高的催化活性,在检测H₂O₂的应用中显示出超强的能力, 5×10^-9mol/L的H₂O₂都可以被检测到,灵敏度较高。更重要的是,利用这种球状的二氧化铈纳米中孔结构,还可以高灵敏度和高选择性的来检测葡萄糖,5×10^-7 mol/L的葡萄糖都可以被检测到,线性范围为1×10^-6到1×10^-4。由于CeO₂中孔纳米粒子制备简单,而且可以在更加苛刻的条件下代替自然酶。构建的过氧化氢和葡萄糖的测试平台不仅充分证明了CeO₂中孔纳米粒子具有过氧化物酶模拟酶的特性,而且还可能同样在其他应用领域如生物传感器,显示其卓越的性能。五、采用一种改进的水热/溶剂热技术,借助表面活性剂的作用下,大量合成了尺寸和形貌均一的四氧化三铁单晶纳米带。仔细讨论了各种实验条件如时间、温度、表面活性剂和水热/溶剂热成分对产物形貌的影响,提出了这种单晶四氧化三铁纳米带的生成机理。用超导量子磁强计考察了纳米带的磁性。并将其用于模拟过氧化物酶来检测过氧化氢的浓度,结果表明这种很薄的单晶纳米带在检测过氧化氢的应用中显示出超强的能力, 2×10^-7 mol/L的过氧化氢都可以被检测到,线性范围为5×10（-7）到1×10^-5。更重要的是,利用这种带状的四氧化三铁纳米结构,还可以高灵敏度和高选择性的来检测葡萄糖,5×10^-8 mol/L的葡萄糖都可以被检测到,线性范围为1×10^-5到1×10^-3。由于四氧化三铁纳米带制备简单,而且可以在更加苛刻的条件下代替自然酶。构建的过氧化氢和葡萄糖的测试平台不仅充分证明了四氧化三铁纳米带具有过氧化物酶模拟酶的特性,而且还可能同样在其他应用领域如生物传感器或生物分离分析显示其卓越的性能。六、利用硫酸亚铁为原料,采用表面活性辅助的水热反应合成了形貌均一的、自组装的、四氧化三铁纳米带组装结构。通过简单的煅烧反应以后,得到了γ-Fe₂O₃和α-Fe₂O₃两种纳米带组装结构,样品的形貌没有发生大的变化。详细研究了这种纳米组装结构的生长过程,提出了可能的生长机理,并发现正壬醇在这种纳米组装结构的形成过程中起着至关重要的作用。这些氧化物纳米组装结构在水处理中显示出了较强的去除水中有机污染物的能力。经分离后,在空气中灼烧可以再生吸附剂,吸附剂可以循环使用,有望用于污水处理剂或其他应用领域。更多还原

【Abstract】 Recently, nanostructured materials have attracted much attention because of their novel optical, electrical, magnetic and catalytic properties, and their technical applications in diverse areas such as the magnetic storage, devices, sensors, medicine images and catalysis. In the present dissertation, several novel functional composite nanostructures were designed and constructed, and the structures and properties of these nanostructures were detailed studied. By means of the developed-hydrothermal/solvothermal method and polyol-mediated process, we have succeeded in developing new structured nanomaterials with the delicate control of their morphologies, structures and properties, and consequently bridging the gap between the functional nanostructures and the nanodevices.The developed-hydrothermal/solvothermal method and polyol-mediated process to achieve several semiconductor oxides with multi-morphologies and structures, and properties and their applications of these nanostructures were detailed studied. The main point of this dissertation is as followed:1. A 3D ZnO nanostructure with sisal-like morphology has been synthesized in the temperature range 120–220℃by a rapid hydrothermal route （30 min） via the assembly of CTA⁺ and Zn（OH）₄^2-. The obtained samples are hexagonal wurtzite structures and they exhibit special optical properties with a red-shift of about 20 nm compared to the corresponding nanorods and nanowires. The sisal, constructed of many nanorods, possesses typical tapering features with tip size 80–100 nm. The effects of CTAB, NaOH, reaction time and temperature were investigated. Results show that the concentration of CTAB and Zn²⁺/OH^- molar ratio play important roles in the fabrication of uniform and pure ZnO samples. On the basis of structural information provided by XRD, SEM, TEM, and HRTEM, a growth mechanism is proposed for the formation of sisal-like 3D ZnO nanostructures.2. One-dimensional （1D） hierarchical nanostructures of ultralong layered K_xMnO₂ （x < 0.3） bundles with diameters 50-100 nm and lengths up to 50-100μm have been successfully prepared by a PEG-assisted hydrothermal method based on the reaction of KMnO4 with 2-ethylhexanol. The obtained samples ascribe to the monoclinic phase and exhibit ferromagnetic behaviors below 32 K and paramagnetic behaviors above 32 K, which may make this system a promising base material for magnetic devices. A series of contrastive experiments have illustrated that 2-ethylhexanol, PEG 400, KOH, and reaction time play an important role in the synthesis of the nanobundles. A possible growth mechanism has been proposed.3. A redox in polyol process was developed to synthesize CeO₂ with controllable superstructures. At the different stages of the reaction, the prepared CeO₂ were readily regulated in its morphologies, which could vary from （2D） nanodisks to （0D） hierarchically nanoporpous nanoparticles （HNPNPs）, and finally to 3D spherical arrays. The growth kinetics of such a process was also studied. The synthesized CeO₂ HNPNPs exhibited high surface area and high catalytic activity as a catalysis for CO oxidation.4. In the present work, we just make use of the novel properties of CeO₂ HNPNPs as peroxidase mimetics to detect H₂O₂ and glucose. The CeO₂ HNPNPs were prepared via a polyol-mediated process. The as-prepared CeO₂ HNPNPs were then used to catalyze the oxidation of a peroxidase substrate 3,3,5,5-tetramethylbenzidine （TMB） by H2O₂ to the oxidized colored product which provides a colorimetric detection of H2O₂. A slow as5x10-9 mol/L H₂O₂ could be detected via our method. More importantly, a sensitive and selective analytical platform for glucose detection was fabricated using glucose oxidase （GOx） and the as-prepared CeO₂ HNPNPs. The analytical platform developed exhibited sensitive and selective detection of glucose with a linear range from 1×10^-6 to 1×10^-4 mol/L.5. One-dimensional Single-Crystalline Magnetite （Fe3O4） Nanobelts with diameters 50 nm and lengths up to 3-5μm have been successfully prepared by a PVP-assisted hydrothermal/solovthermal method. The obtained samples exhibit ferromagnetic behaviors at 300 K, which may make this system a promising base material for magnetic devices. A series of contrastive experiments have illustrated that carbon chain length, PVP K30, and reaction time play an important role in the synthesis of the nanobelts. A possible growth mechanism has been proposed. Furthermore, we just make use of the novel properties of Fe3O4 nanobelts as peroxidase mimetics reported by Yan et al. to detect H2O2 and glucose. The as-prepared Fe3O4 nanobelts were then used to catalyze the oxidation of a peroxidase substrate 3,3,5,5-tetramethylbenzidine （TMB） by H2O2 to the oxidized colored product which provides a colorimetric detection of H2O2. As low as 2x10^-7 mol/L H₂O₂ could be detected with a linear range from 5x 10^-7 to 1x 10^-5 mol/L via our method. More importantly, a sensitive and selective analytical platform for glucose detection was fabricated using glucose oxidase （GOx） and the as-prepared Fe3O4 nanobelts. The analytical platform developed exhibited sensitive and selective detection of glucose with a linear range from 1×10^-5 to 1×10^-3 mol/L.6. We have used FeSO₄·2H₂O, Sodium borohydride. ,two nontoxic and inexpensive reagents, to synthesize Fe₃O₄ single-crystalline nanobelts bundles with uniform, self-assembled, bundlelike nanostructures by a PVP-assisted hydrothermal/solvthermal method.γ-Fe₂O₃,α-Fe₂O₃, could be obtained from Fe₃O₄ without changing their morphologies by a simple calcination procedure. The reaction mechanism and the self-assembly evolution process were studied. The addition of isononanol played a critical role in the synthesis of Fe₃O₄ single-crystalline nanobelts bundles. The as-prepared iron oxide nanomaterials showed an excellent ability to remove pollutants in water treatment and are expected to be useful in many other applications.更多还原