新颖Co3O4分级结构的制备及其光催化性能研究

以聚乙烯醇/醋酸钴复合纳米纤维为模板, 采用模板辅助共沉积技术制备了三维尖晶石型Co₃O₄纳米纤维/晶须分级结构. 并采用SEM, XRD对其形貌和晶型结构进行了表征. 在光催化降解亚甲基蓝(MB)性能实验中, 三维分级结构Co₃O₄表现出比纳米粒子和纤维更好的光催化性能. 这主要归因于Co₃O₄纳米线的次级结构和开放的三维网络结构有利于MB分子和氧分子的扩散和传输, 从而增强MB的光降解反应速率.     

仿生分级结构NiO纳米线/纳米纤维的可控制备及光催化性能

采用静电纺丝技术和"自下而上"的溶液相自组装技术, 制备了具有仿生主次分级结构的三维NiO纳米线/纳米纤维. 采用扫描电子显微镜(SEM)、 X射线衍射仪(XRD)和比表面积分析仪分别对其形貌、 晶型和孔结构进行了表征. 以水体中的有色染料亚甲基蓝为模型污染物, 研究了分级结构NiO纳米线/纳米纤维的光催化性能. 结果表明, 在180 min内, 以分级结构NiO为催化剂时, 亚甲基蓝的降解率达到了97%, 分别是以纳米纤维和纳米粒子为催化剂时的1.24倍和2.16倍.     

Ag+/Ag/ZnO多孔纳米结构纤维材料的制备及可见光催化性能

借助棉花纤维模板, 采用两步法制备了Ag⁺/Ag/ZnO多孔纳米结构纤维材料, 并利用X射线衍射(XRD)、 X射线光电子能谱(XPS)、 扫描电子显微镜(SEM)和紫外-可见光谱(UV-Vis)等对其进行了表征. 以亚甲基蓝(MB)的脱色降解为模型反应, 考察了银修饰量(摩尔分数, 0~1.50%)对ZnO纳米结构纤维材料光催化性能的影响. 结果表明, 利用模板辅助的两步法制备了Ag⁺-Ag共修饰的ZnO多孔纳米结构纤维材料Ag⁺/Ag/ZnO, Ag⁺和Ag通过改变ZnO的晶胞结构、 光吸收特性及形貌等影响其光催化性能; 在可见光条件下, Ag⁺/Ag/ZnO的催化性能优于纯ZnO, 且与修饰量有关.     

Ag/ZnO纳米纤维的制备及光催化性能

采用静电纺丝技术及煅烧法制备了氧化锌纳米纤维, 然后采用水热法将银纳米颗粒负载到了氧化锌纳米纤维表面. 利用X射线衍射(XRD)、 X射线光电子能谱(XPS)、 能量色散X射线光谱(EDX)、 扫描电子显微镜(SEM)及透射电子显微镜(TEM)等技术对合成的Ag/ZnO纳米纤维的结构和组成进行了表征. SEM结果表明, 直径在5~100 nm之间的银纳米颗粒附着在直径在80~330 nm之间的氧化锌纤维表面形成了异质结构. 以常见的有机污染物甲基橙、 亚甲基蓝和罗丹明B等为降解底物, 对Ag/ZnO纳米纤维的光催化性能进行了表征. 结果表明, 负载银纳米颗粒后, 复合催化剂的光催化性能明显提高.     

钛(Ⅳ)离子掺杂的氧化锌多壁纳米纤维结构材料的制备及光催化性能

借助棉花纤维模板、利用两步法制备了Ti⁴⁺/ZnO多壁纳米纤维结构材料,利用热重分析(TG)、X射线衍射(XRD)和扫描电子显微镜(SEM)等技术手段对其进行了表征;以亚甲基蓝(MB)的降解脱色为模型反应,考察了Ti⁴⁺掺杂量对ZnO多壁纳米纤维结构材料光催化性能的影响。 结果表明,利用模板辅助的两步法成功制备了Ti⁴⁺掺杂的ZnO多壁纳米纤维结构材料(Ti⁴⁺/ZnO);Ti⁴⁺的掺入影响ZnO材料的纳米结构,从而使Ti⁴⁺/ZnO的光催化性能明显高于ZnO;Ti⁴⁺/ZnO多壁纳米纤维结构材料良好的光催化性能可主要归于Ti⁴⁺/ZnO材料中活性中心-O^2--Ti⁴⁺-O^2--Zn²⁺-的形成和光生电荷e^--h⁺沿着颗粒间的有效传递。     

高度有序ZnO-SnO_2异质外延枝状纳米结构的制备及其光催化性质研究

采用一种简单的热蒸发法制备了高度有序的ZnO-SnO2异质外延枝状纳米结构。制备过程分两步进行:首先,在氧化铝片基底上制备SnO2纳米线;然后,以此SnO2纳米线为模板在其上生长ZnO纳米线。用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)等手段对产物的形貌、结构进行了表征。XRD表征结果证实第一步和第二步生长的产物分别为SnO2和ZnO。SEM观察结果表明,第一步热蒸发得到直径约100nm、长度达几十微米的SnO2纳米线,第二步热蒸发后得到以第一步SnO2纳米线为主干、沿四个方向有序排列的枝状ZnO纳米结构。TEM观察结果表明,ZnO枝状纳米线沿[001]方向由SnO2纳米线(-101)晶面外延生长。所制备的枝状纳米结构由于具有巨大的比表面积,且外延异质结可以促进电荷的分离和快速转移,因此非常适合于光催化应用。该ZnO-SnO2异质外延枝状纳米结构用于光催化降解甲基橙,表现出优异的性能。     

Ag/ZnO纳米纤维的制备及光催化性能（英文）

采用静电纺丝技术及煅烧法制备了氧化锌纳米纤维,然后采用水热法将银纳米颗粒负载到了氧化锌纳米纤维表面.利用X射线衍射(XRD)、X射线光电子能谱(XPS)、能量色散X射线光谱(EDX)、扫描电子显微镜(SEM)及透射电子显微镜(TEM)等技术对合成的Ag/ZnO纳米纤维的结构和组成进行了表征.SEM结果表明,直径在5~100 nm之间的银纳米颗粒附着在直径在80~330 nm之间的氧化锌纤维表面形成了异质结构.以常见的有机污染物甲基橙、亚甲基蓝和罗丹明B等为降解底物,对Ag/ZnO纳米纤维的光催化性能进行了表征.结果表明,负载银纳米颗粒后,复合催化剂的光催化性能明显提高.     

Ag/ZnO/ZnSe三元异质结的合成及其可见光光催化性能

以Ag纳米线为模板,通过两步水浴法合成了Ag/ZnO/ZnSe三元异质结光催化材料。利用场发射扫描电子显微镜(FESEM)、X射线能谱仪(EDS)、X射线衍射仪(XRD)以及透射电子显微镜(FETEM)对样品的形貌和结构进行了表征。结果显示,Ag/ZnO/ZnSe三元异质结为蠕虫状的Ag/ZnO二元异质结外镶嵌着ZnSe小颗粒。在可见光下,对比纯Ag纳米线、纯ZnO纳米球、Ag/ZnO异质结对罗丹明B的可见光降解效率,结果发现Ag/ZnO/ZnSe异质结表现出了更高的光催化效率。其光催化性能的提高主要是由于Ag/ZnO/ZnSe异质结的作用促使电子空穴对的分离,降低了电子空穴对的复合机率,从而提高了材料的光催化效率。     

硅衬底上聚丙烯酰胺/氧化锌纳米线薄膜蓝色发光二极管

采用高分子络合软模板法利用高分子络合和低温氧化烧结反应,在硅衬底上自组装生长出顶面平滑具有六角柱形结构的ZnO纳米线,并基于此聚丙烯酰胺/ZnO纳米线体系构筑了聚合物基ZnO纳米线发光二极管器件,在相对低的阈值电压下实现了常温常压下电场驱动的蓝色发射光,并且其发光颜色可由其应用的激励电压方便地调控.几乎垂直排列的ZnO纳米线/高分子薄膜在器件中被作为发射层.该方法使用聚合物作为LED器件的粘结剂和发光层的分散介质,稳定了硅衬底上埋置在聚合物薄膜中的ZnO纳米线准阵列并对ZnO纳米晶的表面起钝化作用,防止发光猝灭.结果表明,新技术是一种低成本制备ZnO基紫外/蓝色发光材料的工艺,并且减少了以往工艺中要求ZnO薄膜p型掺杂的麻烦.     

ZnO纳米纤维的静电纺丝及其光催化性能的研究

以聚乙烯醇溶液为络合剂与醋酸锌反应制得前驱体溶液,采用静电纺丝法制备PVA/Zn(Ac)2复合纳米纤维,经过高温煅烧得到直径为100 nm的ZnO纳米纤维,采用差热-热重分析、红外光谱分析、X射线粉末衍射分析及扫描电镜等手段对其进行了表征.光催化降解酸性品红溶液的实验结果表明,太阳光照65 min使质量浓度为45 mg/L酸性品红水溶液的脱色率达93%;另外,重复使用ZnO纳米纤维4次之后,其光催化降解率仍能达到70%以上.这充分说明ZnO纳米纤维具有良好的光催化性能.     

Formation of well-aligned ZnGa(2)O(4) nanowires from Ga(2)O(3)/ZnO core-shell nanowires via a Ga(2)O(3)/ZnGa(2)O(4) epitaxial relationship

Formation of well-aligned and single-crystalline ZnGa(2)O(4) nanowires on sapphire (0001) substrates has been achieved via annealing of the Ga(2)O(3)/ZnO core-shell nanowires. Ga(2)O(3)/ZnO core-shell nanowires were prepared using a two-step method. The thickness of the original ZnO shell and the thermal budget of the annealing process play crucial roles for preparing single-crystalline ZnGa(2)O(4) nanowires. Structural analyses of the annealed nanowires reveal the existence of an epitaxial relationship between ZnGa(2)O(4) and Ga(2)O(3) phases during the solid-state reaction. A strong CL emission band centered at 360 nm and a small tail at 680 nm are obtained at room temperature from the single-crystalline ZnGa(2)O(4) nanowires.     

ZnO掺杂的SnO_2纳米纤维的制备、表征及气敏机理(英文)

以二水氯化亚锡(SnCl2·2H2O)为盐原料,采用静电纺丝的方法制备了SnO2纳米纤维.为了研究ZnO掺杂对SnO2形貌、结构及化学成分的影响,分别制备了不同含量ZnO掺杂的SnO2/ZnO复合材料.利用热重-差热分析(TG-DTA)、X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱仪、扫描电镜(SEM)及能量色散X射线(EDX)光谱对材料的结晶学特性及微结构进行了表征.制备的SnO2/ZnO复合材料是由纳米量级的小颗粒构成的分级结构材料.ZnO含量不同,对应的SnO2/ZnO复合材料结构不同.表征结果表明ZnO的掺杂量对SnO2材料的形貌及结构均起着重要作用.将制备的不同ZnO含量的SnO2/ZnO复合材料进行气敏测试,测试结果表明,Sn:Zn摩尔比为1:1制作的气敏元件对甲醇的灵敏度优于其它摩尔比的气敏元件.讨论了SnO2/ZnO复合材料气敏元件的敏感机理.同时针对Sn:Zn摩尔比为1:1时表现出最好的气敏响应,分析了其原因,包括Zn的替位式掺杂行为、ZnO的催化作用、过量ZnO对SnO2生长的抑制作用以及SnO2与ZnO晶粒界面处的异质结.     

Synthesis and thermal stability of ZnO nanowires

ZnO nanowires (NWs) were synthesized on Au-coated Si (100) substrates by vapor transport method. The effect of high temperature annealing on the structural and chemical composition as well as thermal stability was studied. The as-prepared ZnO NWs was nearly stoichiometric and identified as hexagonal ZnO phase. After annealing at 1,473 K, the atomic ratio of O/Zn, the intensity of the diffraction peaks, and the diameter of nanowires were increased. The ZnO NWs were fragmented into nanocrystals and the fragments coalesced with each other after annealing at 1,673 K. The thermal stability of ZnO NWs was studied by thermo-gravimetric (TG) analysis. A sharp increase in the TG curves was observed and can be attributed to the oxidation of some possibly presented Zn atoms. The activation energy of oxidation of Zn interstitial atoms was found to be 484.81 kJ mol^?1. A mass gain peak was observed after annealing at 1,473 K, but it was completely eliminated after annealing at 1,673 K.     

Short-period superlattice structure of Sn-doped In(2)O(3)(ZnO)(4) and In(2)O(3)(ZnO)(5) nanowires

Two longitudinal superlattice structures of In(2)O(3)(ZnO)(4) and In(2)O(3)(ZnO)(5) nanowires were exclusively produced by a thermal evaporation method. The diameter is periodically modulated in the range of 50-90 nm. The nanowires consist of one In-O layer and five (or six) layered Zn-O slabs stacked alternately perpendicular to the long axis, with a modulation period of 1.65 (or 1.9) nm. These superlattice nanowires were doped with 6-8% Sn. The X-ray diffraction pattern reveals the structural defects of wurtzite ZnO crystals due to the In/Sn incorporation. The high-resolution X-ray photoelectron spectrum suggests that In and Sn withdraw the electrons from Zn and enhance the number of dangling-bond O 2p states, resulting in the reduction of the band gap. Photoluminescence and cathodoluminescence exhibit the peak shift of near band edge emission to the lower energy and the enhancement of green emission as the In/Sn content increases.     

Preparation of ZnO Nanowires and Study of Surface‐adsorbate Interaction by Fourier‐Transform Infrared Spectroscopy

To study the surface‐adsorbate properties of ZnO nanowires, a hydrothermal method was modified to grow ZnO nanowires directly on ZnSe, which were then characterized by attenuated total reflection infrared (ATR‐IR) spectroscopy. To prepare ZnO nanowires directly on ATR sensing element of ZnSe, ZnO seed layers were first formed by annealing of ZnO seeds on ZnSe surfaces. The ZnO seed layers then were exposed to growth solution, forming ZnO nanowires directly on the ATR crystals. The interaction properties of the resulting surfaces were studied by an ATR‐IR method. The diameter, length and distribution of the ZnO nanowires can be tuned by adjusting the growth conditions, particularly the growing time and the concentrations of reagents. Two surfaces, namely Zn‐rich and Zn‐O ion‐pair surfaces were studied in detail for their adsorption properties toward compounds bearing different functional groups. By examination of several volatile organic compounds (VOCs), it was found that the Zn‐rich surface is less selective and interacts with compounds bearing the functional groups of amino and hydroxyl. The Zn‐O ion‐pair surface is more selective and a much stronger interaction was observed with non‐aromatic amino compounds. These results indicate that the improving of the selectivity of a ZnO‐based sensing device can be achieved by tuning the surface structure of the ZnO nanomaterials.     

Controllable assembly of aligned ZnO nanowires/belts arrays

We describe a simple method to assemble ZnO nanowires/belts into highly ordered arrays. ZnCu(2) alloy was used as the Zn source, which reacted with water vapor to generate ZnO nanocrystals. The reaction was performed in a mild way, which facilitated the easy control of the reaction conditions. By simply controlling the water bath temperature and carrier gas flux in our experiments, we obtained ZnO nanowires/belts aligned to form ordered arrays. The highly ordered nature of the ZnO arrays is suggested to be related both with the polarities of the H(2)O molecule and the ZnO (0001) surface. Photoluminescence (PL) microscopy revealed that the comblike structures had waveguide properties, where green light enhancement was observed at the tips of the branches. The light enhancement property reveals their promising applications as light source arrays.     

Facile fabrication of hierarchical ZnO nanowire aggregates using rose-like peroxide precursor as the inorganic template

The complex rose-like inorganic templates assembled by the ZnO/ZnO₂ hybrid nanosheets have been constructed with hydrogen peroxide as an additive to control the structure of a precursor. The surface morphologies of the inorganic templates can be controlled by varying the reaction time and the amount of hydrogen peroxide. The process of the precursor growth takes a dissolution-growth route under hydrothermal conditions. The chemical composition of the precursor is determined by X-ray diffraction (XRD) and Raman analyses, indicating the existence of peroxide in the precursor. Combined with transmission electron microscopy (TEM) data, the ZnO/ZnO₂ hybrid precursor is proposed to act as an inorganic template for the growth of secondary crystal structures. The dandelion-like ZnO crystal is fabricated by using rose-like peroxide precursor as the inorganic template. The structural evolution of hierarchical ZnO crystal is studied by monitoring the influence of the reaction time.     

ZnO/CuO hetero-hierarchical nanotrees array: hydrothermal preparation and self-cleaning properties

ZnO/CuO heterohierarchical nanotrees array has been prepared via a simple hydrothermal approach combined with thermal oxidation method on Cu substrates. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffractometer(XRD) are employed to characterize and analyze the as-synthesized samples. The results demonstrate that the secondary growth of ZnO nanorods enclose with CuO nanowires, leading to the formation of ZnO/CuO heterohierarchical nanotrees array. The hierarchical nanostructures have isotropic crystal symmetry and they have no 6-fold (or 4-fold or 2-fold) symmetry as general epitaxial growth. Enlightened by the similarity with microstructure of lotus, the wettability of ZnO/CuO heterohierarchical nanotrees array has been investigated. It is revealed that as-prepared ZnO/CuO nanotrees array after silanization present remarkable superhydrophobic performance, which is attributed to the trapped air and hierarchical roughness. Furthermore, their wettability could be manipulated by the morphologies of hierarchical ZnO nanorods. At the optimal condition, the greatest static angle of water droplet on the obtained heterohierarchical nanotrees array could reach almost 170°, and this substrate could be used as self-cleaning surface.     

Porous ZnCo2O4 nanowires synthesis via sacrificial templates: high-performance anode materials of Li-ion batteries

A simple microemulsion-based method has been developed to synthesize ZnCo(2)(C(2)O(4))(3) nanowires that can be transformed to porous ZnCo(2)O(4) nanowires under annealing conditions. The morphology of porous ZnCo(2)O(4) nanowires can be tuned by the initial ZnCo(2)(C(2)O(4))(3) nanowires and the annealing temperatures. The as-synthesized porous ZnCo(2)O(4) nanowires have been applied as anode materials of Li-ion batteries, which show superior capacity and cycling performance. The porous one-dimensional (1D) nanostructures and large surface area are responsible for the superior performance. Moreover, it is indicated that porous ZnCo(2)O(4) nanowires synthesized at low annealing temperature (500 °C) show larger capacity and better cycling performance than that prepared at high annealing temperature (700 °C), because of their higher porosity and larger surface area.