PVP导向ZnO纳米线、纳米棒的可控溶剂热合成及其生长机理研究

本文采用强碱性的溶剂热法,通过调控反应温度、时间、反应物投料比、特别是添加剂等影响因素,可控合成了两种不同形貌的一维ZnO纳米材料.利用透射电镜(TEM)和扫描电镜(SEM)研究了不同影响因素对ZnO产物形貌的影响.着重分析了添加剂聚乙烯吡咯烷酮(PVP)与纳米ZnO或其生长基元的络合作用,及其对纳米ZnO形貌的控制作用,并总结出强碱性溶剂热合成中反应温度、体系压强和pH值对ZnO产物形貌的作用机理.     

棒状纳米氧化锌制备工艺优化及脱硫机理研究

ZnO脱硫剂有着优良的脱硫性能，在H2S脱除的过程中得到广泛应用。本文采用均匀沉淀法，研究了不同反应温度、反应时间对纳米ZnO制备的影响，得到棒状纳米ZnO制备的最佳工艺：在温度为60℃下反应6h，可以制得成分纯净、形貌为棒状且分布均匀的纳米ZnO。以制得的ZnO为脱硫剂，探讨脱硫时间对脱硫剂和脱硫产物的影响，得到ZnO的脱硫机理。     

水热法制备的纳米氧化锌阵列及在棉织物上的应用

以硝酸锌和六亚甲基四胺为原料,采用低温水浴法在棉织物表面实现ZnO纳米棒阵列生长的控制,并探讨了反应物溶液的浓度、反应温度、反应时间对ZnO纳米棒阵列生长的影响,同时对所制备的样品进行了抗紫外、光催化等测试、表征及性能分析。结果表明:棉织物表面生长的ZnO纳米棒结构为六方纤锌矿晶体;在反应物溶液浓度为0.025 mol/L,反应温度为90℃,反应时间为3 h时,制备得到形貌规整和定向生长的ZnO纳米棒阵列,赋予棉织物良好的光催化、抗紫外、自清洁等性能。     

液相合成纳米氧化锌及其光催化性能探讨

以硝酸锌和氢氧化钠为原料,分别以水和醇作为溶剂,采用液相直接沉淀法合成纳米氧化锌。在以水为反应溶剂条件下,研究了反应时间、反应温度、反应物浓度和反应物配比对纳米氧化锌中位径和形貌的影响,得到制备较小中位径及合适长径比纳米氧化锌的最优反应条件,即:反应时间为3 h、反应温度为70 ℃、锌离子浓度为0.5 mol/L、锌离子与氢氧根浓度比为1:2。在上述最优反应条件下,研究了不同醇溶剂对纳米氧化锌中位径、形貌及其光催化性能的影响。研究发现,随着溶剂碳链长度的增长,纳米氧化锌中位径呈现上下波动,无明显变化规律,形貌由球状向柱状发展,光催化性能总体不断减弱。     

溶剂热法合成硫化镉微晶工艺研究

以氯化镉为前驱体,硫化钠、硫代乙酰胺、硫脲等为硫源,乙二醇、乙醇等为溶剂,通过溶剂热法制备硫化镉微晶.设计L9(34)正交试验,探讨了反应温度、反应时间等对硫化镉微晶大小和形貌的影响.所得产物经离心、洗涤、干燥后,用纳米粒度仪分别测定各产物的平均粒径,同时用扫描电子显微镜测定部分产物的大小和形貌,并用极差分析法找寻最佳合成工艺.结果表明:以硫代乙酰胺为硫源,乙二醇为溶剂,反应温度为100℃,反应时间为10 h,可得到直径为0.5～0.7μm的片状硫化镉晶体.该方法工艺简单,反应条件温和,制备的硫化镉晶体大小分布均匀,形貌单一.     

氢氧化镁纳米棒的制备和表征

以碱式氯化镁纳米棒为前驱物,采用沉淀转化法制备出直径100～200nm,长约6μm的氢氧化镁单晶纳米棒。通过X-射线衍射(XRD)、扫描电子显微镜(SEM)和选区电子衍射(SAED)对产物进行表征与检测,研究了溶剂、沉淀转化剂类型、氢氧化钠溶液初始浓度、反应物物质的量比、反应温度及反应时间等制备工艺参数对产物形貌的影响,获得的最佳制备工艺条件为:溶剂为乙醇,沉淀转化剂为氢氧化钠,氢氧化钠溶液初始浓度为2mol/L,氢氧化钠与碱式氯化镁的物质的量比为2:1,反应温度为60℃,反应时间为1h。     

水热反应条件对纳米钼酸银形貌的影响

以钼酸铵和硝酸银为原料,采用一步水热法制备了不同形貌的纳米钼酸银(Ag_2Mo_2O_7),探究了反应温度、反应时间、Ag NO_3浓度和表面活性剂聚乙烯吡咯烷酮(PVP)对产物结构及形貌的影响。利用X-射线衍射仪(XRD)、扫描电子显微镜(SEM)对纳米钼酸银的物相和形貌进行了表征。结果表明,通过改变水热反应条件可以得到纳米线、纳米棒、纳米片等不同形貌的钼酸银,其中反应温度和表面活性剂PVP对纳米钼酸银的形貌影响显著。     

活化制备枣核碳材料/ZnO新型复合材料及其电化学性能

红枣枣核的高效开发利用一直是研究的热点.以红枣核粉为骨架载体,先经HCl活化处理,再通过水热法在其表面生长纳米ZnO制备红枣核/ZnO复合材料,并通过改变原料配比、反应温度、反应时间、p H值研究其对材料性能的影响.XRD及FT-IR结果表明ZnO及复合材料的生成,SEM结果表明不同的反应条件对复合材料的表面形貌有很大...     

金属Pd掺杂ZnO纳米材料的制备及其气敏性能研究

以氯化锌、尿素、聚乙烯吡咯烷酮为原料,不同配比的乙醇和水为反应溶剂,用水热法制备出尺寸、形貌不同的ZnO纳米材料。采用X射线衍射(XRD)、场发射扫描电镜(FESEM)、透射电镜(TEM)研究产物的组成、结构及形貌。表征结果显示三种不同反应条件分别生成了刺球状、雪片状和片球状三种不同形貌的ZnO,经过自组装过程在ZnO材料表面掺杂上纳米Pd颗粒,气敏性能测试结果表明:负载纳米Pd颗粒的ZnO灵敏度比纯ZnO灵敏度有不同程度的提高,研究表明金属Pd颗粒掺杂的ZnO为丙酮传感器的理想材料。     

水热合成六方柱状氧化锌及其光催化性能研究

以二水醋酸锌和六次甲基四胺为原料,采用温和水热法制备了六方柱状ZnO。采用X射线衍射(XRD)、扫描电镜(SEM)和紫外可见光谱对其物相、形貌和光催化性能进行了分析,着重研究了不同的反应条件对ZnO形貌的影响,探讨了六方柱状ZnO的形成机理。结果表明:溶液浓度、pH值、反应温度和反应时间对生成晶体的形貌和晶体质量都会产生影响。制备结晶良好的ZnO的最佳反应条件为:反应液浓度为0.57mol/L,pH值为6.0,反应温度为97℃,反应时间为16h。六方柱状ZnO晶体的形成机理是在一定的水热条件下,醋酸锌与六次甲基四胺水解后形成晶核,由于(0001)晶面的生长速率大于其它晶面,以及(0001)晶面易俘获原子,使得成核后的ZnO沿(0001)面定向生长,最终形成六方柱状结构。     

Synthesis of ZnO Microtubes by a Facile Aqueous Solution Process

Zinc oxide (ZnO) microtubes 1.0–2.5 μm in length, 300–500 nm in outer diameter, and 50–80 nm in wall thickness have been synthesized by a facile aqueous solution process, by simply dropping ammonia water into zinc chloride aqueous solution. This new method shows some advantages, such as synthesis under atmospheric pressure at a glass flask, low cost and easy control. The growth mechanism of ZnO microtubes is discussed in this paper. The different growth rates of ZnO crystal facets create the different crystallographic facets of hexagonal microtubes. And the polar structure results in the formation of ZnO microtubes for minimizing the spontaneous polarization energy. The dependence of morphologies of ZnO particles on the reaction temperature is also investigated. The scanning electron microscopy results show that the reaction temperature plays an important role in the morphologies of ZnO particles.     

A two-step route to synthesize highly oriented ZnO nanotube arrays

Large-scale and highly oriented ZnO nanotube arrays are synthesized on transparent conductive glass substrates by a two-step route. First, ZnO nanorod arrays were prepared by electrochemical deposition from an aqueous solution of zinc nitrate. Then, hollow ZnO nanotubes were obtained by the selective dissolution of the electrodeposited ZnO nanorods in potassium hydroxide solution. Field emission scanning electron microscopy (FESEM) and X-ray powder diffraction (XRD) have been used to characterize the morphology and structure of the derived products. The effect of the concentration of alkali, dissolution time, and temperature on the formation process and morphologies of ZnO nanotube arrays has been discussed.     

纳米ZnO晶须锌的蒸气氧化法制备及荧光性能

用锌蒸气直接氧化法合成不同形貌的纳米ZnO晶须,考察氧气含量和温度对ZnO晶须形貌的影响。通过调节反应条件,可以获得一维线状、三维四针状和多针状ZnO晶须,探讨了ZnO晶须和二次片晶的形成机理。样品的室温荧光性能分析表明：500nm附近（450～550nm）较宽的可见光发射峰,系ZnO晶须表面态效应和氧空位引发的光生空...     

Effects of etching parameters on ZnO nanotubes evolved from hydrothermally synthesized ZnO nanorods

This paper reports fabrication and characterization of ZnO nanotubes on Au cylindrical spirals. Highly oriented single-crystalline ZnO nanorods were hydrothermally synthesized on Au cylindrical spirals and were etched in NaOH solution to form nanotubes. Effects of etching parameters on the lengths, wall thicknesses and morphologies of the ZnO nanotubes were studied with the etching period, etching temperature and NaOH concentration regulated respectively. It turns out that the etching parameters affect significantly the morphologies of the ZnO nanotubes but negligibly the lengths and wall thicknesses. The surfaces of the ZnO nanotube-coated Au cylindrical spirals tend to be Gaussian rough ones as the etching parameters become larger. Adjusting the etching temperature readily gives rise to perfect ZnO nanotubes. The results are beneficial for large-scale preparation of ZnO nanotubes with controllable sizes and morphologies in nanodevices.     

氧化锌纳米棒及纳米管阵列薄膜的制备

采用水溶液法在ITO玻璃上电沉积了高度取向的ZnO纳米棒阵列,并通过碱液化学浸蚀法获得了ZnO纳米管.分别探讨温度及沉积时间对ZnO纳米棒阵列薄膜沉积的影响,和温度及浸蚀时间对浸蚀ZnO纳米管阵列薄膜的影响,采用SEM测试方法分析了ZnO纳米管阵列薄膜的最终形态.     

片状纳米ZnO的合成及其光催化活性研究

以六次甲基四胺为沉淀剂,氯代十六烷基吡啶为形貌控制剂,采用水热-均匀沉淀法合成了片状ZnO微晶,考察了合成方法、沉淀剂用量及水热反应温度等条件对产物形貌、尺寸及光学性质的影响,并以甲基橙为模型污染物研究了样品的光催化性能。结果表明,所得样品均为六方纤锌矿型ZnO,当锌盐和六次甲基四胺的摩尔比为1∶2,采用水热-均匀沉淀法于120℃水热条件下反应所得到的样品其形貌最佳,且在250~400 nm波长范围内对光有很强的吸收,对甲基橙的光降解具有较高的光催化活性,自然光照5 h后甲基橙的脱色率可达90.8%。     

Effect of the morphology of solution‐grown ZnO nanostructures on gas‐sensing properties

Despite the great potential of zinc oxide (ZnO) nanostructures as a sensing material for high‐performance gas sensors, the correlation between the morphology of ZnO nanostructure and its gas‐sensing performance has not been systematically investigated yet. In this work, ZnO nanostructures with controlled morphologies were synthesized by low‐temperature solution route and chemical bath deposition method. Thin film gas sensors were fabricated from the nanostructures and the sensor performance such as the response, recovery time, and stability was examined for several gases. It is demonstrated that the gas‐sensing performance of a ZnO nanostructure sensor is strongly influenced by its morphology. One dimensional ZnO nanocones are highly promising for practical application to gas sensors, due to their large surface area per unit mass and unique conical structure.     

XPS and optical studies of different morphologies of ZnO nanostructures prepared by microwave methods

Zinc oxide (ZnO) nanostructures of various morphologies were prepared using a microwave-assisted aqueous solution method. Herein, a comparative study between three different morphologies of ZnO nanostructures, namely nanoparticles (NPs), nanoflowers (NFs) and nanorods (NRs) has been reviewed and presented. The morphologies of the prepared powders have been studied using field effect scanning electron microscopy (FESEM). X-ray diffraction (XRD) results prove that ZnO nanorods have biggest crystallite size compared with nanoflowers and nanoparticles. The texture coefficient (T_c) of three morphologies has been calculated. The T_c changed with varying morphology. A comparative study of surfaces of NPs, NFs and NRs were investigated using X-ray photoelectron spectroscopy (XPS). The possible growth mechanisms of ZnO NPs, NFs and NRs have been described. The optical properties of the ZnO nanostructures of various morphologies have been investigated and showed that the biggest crystallite size of ZnO nanostructures has lowest band gap energy. The obtained results are in agreement with experimental and theoretical data of other researchers.     

微波均相沉淀法制备纳米ZnO及其光催化性能

以硫酸锌和尿素为原料,采用微波均相沉淀法制备出了纳米ZnO. 探讨了反应物配比、反应物浓度、反应时间、反应温度等条件对产物的影响. 并用TEM, IR, TGA, XRD, UV-Vis等测试手段对其进行了表征. 利用紫外-可见分光光度计测试了光吸收特性,发现纳米ZnO对200~380 nm波长范围的光有很强的吸收性,在可见光范围内也有较强的吸收. 研究了纳米ZnO光催化降解甲基橙的动力学行为,在紫外光直接照射下,光催化降解甲基橙,以分光光度法测量甲基橙的即时浓度,从而得出了不同条件下甲基橙降解的脱色速率,以比较不同的降解效果.     

Morphology controlled synthesis of ZnO particles through the oxidation of Al–Zn mixture

ZnO particles with different morphologies were synthesized through a simple oxidation process of Al–Zn mixtures in air. The morphologies significantly depended on the Zn content in Al–Zn mixture and the oxidation time. Rod-based brushes, typical tetrapods, and novel tetrapods with triangular wedges were synthesized with the increase of Zn content in Al–Zn mixture. The morphology was also changed from rod to tetrapod shape with oxidation time. The results indicate that the concentration of Zn and the oxidation time might be responsible for the different morphologies of ZnO particles. XRD spectra showed that the ZnO particles were a hexagonal wurtzite structure.