以PVA为溶剂ZnO薄膜的液相法制备及其机理研究

以聚乙稀醇(PVA)水溶液为溶剂,采用液相法制备了高度c轴取向的ZnO薄膜。采用XRD、Raman以及AFM分析了退火温度与涂层厚度对ZnO薄膜的影响。结果表明,随着退火温度的提高,ZnO薄膜的结晶度及其均方根粗糙度有所提高;同时厚度的增加使得ZnO薄膜的单一取向性减弱。其生长机理可表述为:在每一层涂层中一致或不一致的成核同时产生,通过层内与层间晶粒的聚合、联并,最后形成具有(002)取向的柱状与颗粒状并存的ZnO连续膜。     

Zn/纳米棒阵列ZnO/聚噻吩复合电极的制备及光电化学性质

使用简单的水热法在锌片上生长ZnO纳米棒阵列,并用电化学共聚制备了ZnO纳米棒阵列与聚噻吩(Zn/ZnO/PTH)复合膜。通过X射线衍射(XRD)、扫描电子显微镜(SEM)等手段对ZnO的结构和形貌进行表征,XRD结果表明产物为六方纤锌矿型ZnO。SEM结果表明,在垂直锌片方向生长了包括纳米棒、纳米片、纳米线的表面光滑的ZnO纳米阵列,其中以纳米棒为主,其直径为30～100nm,长度1μm。用光电流作用谱、光电流-电势图研究了Zn/ZnO/PTH电极的光电转换性质。结果表明,PTH修饰ZnO/Zn电极可使光电流产生波长发生明显红移,使其光电转换效率提高了4倍,填充因子FF=33%,光电转换效率η=1.25%。     

AZO晶种层对ZnO纳米线生长及紫外光电导性能的影响

采用溶液化学法实现了在Zn(NO3)2/C6H12N4混合溶液中ZnO纳米线在AZO薄膜修饰过衬底上生长。AZO薄膜由射频磁控溅射法制备,通过溅射时间和基底温度的变化改变薄膜形态,重点研究了不同薄膜形态对ZnO纳米线形貌和结构的影响,最终在溅射2h、基底温度250℃晶种上得到垂直于衬底、高度平行取向的ZnO纳米线阵列。在此基础上研究了不同形貌ZnO纳米线阵列的紫外光电导性能差异。结果表明,垂直生长的纳米线较倒伏纳米线紫外响应迅速,分析认为是紫外光照下曝光面积不同造成的。     

Si基ZnO纳米结构太阳能电池光伏性能研究

在洁净的p型Si片上通过旋涂法组装了单层有序排列的聚苯乙烯微球(Polystyrene spheres,PS)阵列模板,然后在PS模板上旋涂1层ZnO先驱薄膜,清洗掉PS模板,制得周期性ZnO先驱薄膜点阵,再通过水热法生长ZnO纳米棒。采用X射线衍射(XRD)、扫描电镜(SEM)对样品进行表征,结果显示ZnO薄膜为柱状ZnO阵列,基于Si衬底沿c轴择优生长。以150W氙灯为模拟光源,照射Si/ZnO异质结太阳能电池器件,通过万用电表测试其伏安特性。性能最好的样品的光电转换效率为1.23%,填充因子为62%。     

用水热法制备超疏水性ZnO纳米棒薄膜

采用简单的水热法制备了超疏水性ZnO纳米棒薄膜,在用磁控溅射在Si(111)衬底上生长一层ZnO籽晶层的基础上,利用水热法制备了空间取向一致的ZnO纳米棒阵列,经修饰后由亲水性转变为超疏水性.用扫描电子显微镜、X射线衍射对样品表面和结构特征进行了表征,用接触角测量仪测出水滴在ZnO纳米棒薄膜表面的接触角为(160±1)°,滚动角为5°.     

ZnO/TiO_2复合纳米材料的制备及其在染料敏化太阳电池中的运用

本文在长有ZnO纳米粒子作为"种子层"的FTO基底上用水热合成法制备了取向高度一致的ZnO纳米线阵列,用TiCl4的异丙醇溶液在ZnO纳米线阵列的表面生长了纳米结构的TiO2。利用扫描电子显微镜、能量散射谱、X射线衍射分别表征纳米材料的形貌和结构,用Raman光谱研究了材料的晶格结构特性。染料敏化太阳电池的性能测试表明,与纯ZnO作为光阳极相比,ZnO/TiO2复合纳米材料作为光阳极的器件,开路电压和填充因子都得到了提高。     

溶液法制备ZnO纳米阵列的影响因素及光催化活性

利用无水醋酸锌原位水解生成的纳米ZnO作晶种,通过溶液法制备ZnO纳米阵列,研究反应过程中各因素对ZnO纳米阵列形貌的影响,并对制得的ZnO纳米阵列的光催化活性进行研究。结果表明:采用浸涂方式制备晶种,生长得到的ZnO纳米阵列在衬底表面均匀密集分布;采用喷涂方式制备晶种,生长得到的ZnO纳米阵列存在着较大的空白区域。在晶种前驱体溶液中添加二乙醇胺或甲酰胺,会引起纳米ZnO成核的聚集,不利于制得分布均匀的ZnO纳米阵列。反应溶液pH=6.7时,可得到均匀、密集且取向性良好的ZnO纳米阵列结构。以不锈钢金属网为基底制备的ZnO纳米阵列应用于15mg/L甲基橙的光催化降解,3h即降解完全,且进行连续三次反应后仍表现出良好的光催化活性。     

液相沉淀法制备氧化锌-壳聚糖复合材料及其抗菌性能

以硝酸锌(zinc nitrate, Zn(NO₃)₂)为锌源，以壳聚糖(chitosan, CS)为基底，以氢氧化钠(sodium hydroxide, NaOH)为沉淀剂，采用液相沉淀法制备氧化锌-壳聚糖(zinc oxide-chitosan, ZnO-CS)复合材料；借助扫描电镜、 X射线衍射分析、热重分析、 X射线光电子能谱、红外光谱和紫外吸收光谱等手段进行表征，考察ZnO-CS复合材料的形貌、结构组成以及ZnO在CS表面的吸附情况；将ZnO-CS悬浊液涂抹在新鲜熟白米上进行ZnO-CS复合材料的抗菌性能测试。结果表明：Zn²⁺-CS表面首先生长了一层棒状ZnO粒子膜；通过受热反应CS表面的氨基与Zn²⁺、 ZnO形成交联网络，使棒状ZnO进一步生长形成片状ZnO;CS表面的氨基所形成的交联网络吸附ZnO,得到ZnO-CS复合材料；在时间为6 d时，用ZnO-CS悬浊液处理后的新鲜熟白米没有生成菌落，在时间为12 d时菌落无明显扩散，表明ZnO-CS复合材料具有良好的抗菌作用。     

ZnO纳米棒/ZnCo2O4纳米片异质结的制备及其光电探测性能

ZnO纳米材料异质结是构筑高性能紫外光电探测器的有力候选之一。本工作中, 设计并制备了一种新型ZnO纳米棒/ZnCo₂O₄纳米片异质结, 研究了其电学性能及光电探测性能。使用油水界面自组装, 将ZnCo₂O₄纳米片在ITO玻璃上组装为均匀的薄膜; 通过调控ZnO种子层厚度, 在ZnCo₂O₄纳米片薄膜上水热生长了取向一致、密度适中的ZnO纳米棒阵列, 获得了高质量的ZnO纳米棒/ZnCo₂O₄纳米片异质结。该异质结具有优良的整流特性, 整流比达到673.7; 其工作在反偏状态时, 光暗电流比超过2个量级, 紫外-可见判别比为29.4, 在光电探测中有良好的波长选择特性。研究表明, 该异质结有潜力应用于构筑高性能紫外光电探测器。     

反应沉积法制备c轴取向ZnO薄膜及表征

以二水合醋酸Zn为原料 ,采用反应沉积方法在非晶玻璃衬底上制备出了高度c轴取向、结晶良好的ZnO薄膜。研究了不同衬底温度和Zn源温度对ZnO薄膜性质的影响 ,探讨了不同衬底温度和Zn源温度下生长ZnO薄膜的最佳参数。本文还讨论了该方法制备ZnO薄膜的沉积机制及优化条件下样品的透光特性。     

ZnO(101) films by pulsed reactive crossed-beam laser ablation

We have employed pulsed reactive crossed-beam laser ablation (PRCLA) to deposit a (101) oriented ZnO film. In this method, a supersonic jet of oxygen pulse is made to cross the laser plume from a zinc metal target while being carried to the Si(111) substrate. The obtained deposit was nanocrystalline ZnO as confirmed by a host of characterization techniques. When the substrate was held at varying temperatures, from room temperature to 900°C, the crystallinity of the obtained films increased as expected, but importantly, the crystallographic orientation of the films was varied. High substrate temperatures produced the usual (001) oriented films, while lower substrate temperatures gave rise to increasingly (101) oriented films. The substrate held at room temperature contained only the (101) orientation. The film morphology also varied with the substrate temperature, from being nanoparticulate to rod-like deposits for higher deposition temperatures. Surprisingly, the (101) orientation showed reactivity with acetone forming carbonaceous nanostructures on the surface.     

微米棒构筑的多脚状ZnO水热合成及生长机理探讨

以Zn(CH3COO)2和NH3·H2O生成的Zn(NH3)2 4 为前驱体,采用水热法制备了多脚状ZnO微晶,用XRD、SEM、TEM及UV-Vis进行了鉴定和表征,并对其生长机理进行了初步探讨.结果表明,多脚状ZnO微晶由微米棒构筑,属六方晶系,在短紫外光区具有较强的光吸收性能.     

Effect of solution concentration on surface morphology and photocatalytic activity of ZnO thin films synthesized by hydrothermal methods

ZnO thin films were synthesized via hydrothermal method on silicon substrate at various solution concentrations. The thin films were characterized by X-ray diffraction, field-emission scanning electron microscope and UV–Vis spectrophotometer. The results show that the thin films are polycrystalline with wurtzite hexagonal structure. The T _c values of (101) surface of the thin film increase from 0.929 to 1.840 at first, and then decrease to 0.779 with increasing solution concentration. The preferential orientation along the (101) crystal surface can be controlled by changing the solution concentration. Solution concentration has a significant effect on surface morphology of the thin films. The optical band gap of the thin films decreases, when the solution concentration of zinc nitrate hexahydrate increases from 0.01 to 0.06 mol/L and then increases when the solution concentration of zinc nitrate hexahydrate further increases to 0.08 mol/L. Photocatalytic activity of the thin films on degradation of methyl orange under UV light irradiation was studied in detail. The ZnO thin film with many cracks prepared from 0.01 mol/L shows the higher photocatalytic activity but the tower-like ZnO thin film prepared from 0.08 mol/L reveals the lower photocatalytic activity. Therefore, the photocatalytic activity of the thin films are mainly relate to surface morphology and crystallographic orientation.     

Vapor-phase synthesis of aligned zinc oxide nanorod arrays on various substrates

Zinc oxide nanorod arrays have been grown on Si(100), Si(111), and glass substrates by low-pres-sure chemical vapor deposition from elemental zinc and oxygen. Under the experimental conditions of this study, nanorods grow along the c-axis and are predominantly normal to the substrate surface, independent of the crystallographic orientation of the substrate. The cathodoluminescence spectra of all the samples obtained show one strong emission band in the UV spectral region, due to free-exciton recombination, which attests to good stoichiometry of the ZnO nanocrystals. The uniformity of the arrays correlates with the density of nanorods per unit area and their thickness.     

纵向多孔及实心ZnO微纳米棒的制备、表征及其光催化性能研究

以硝酸锌和六次甲基四胺为原料,水为溶剂,采用低温水热法制备出具有优异光催化性能的六方纤锌矿结构ZnO微纳米棒,并研究了合成过程中磁力搅拌及原料溶液浓度对制备产物形貌及光催化性能的影响,建立了其光催化降解甲基橙的动力学方程。结果表明,搅拌条件下制备的产物为纵向多孔的棒状ZnO,无搅拌条件下制备的产物为实心ZnO纳米棒.优选出的硝酸锌和六次甲基四胺浓度均为0.025mol/L。相比于实心ZnO纳米棒,纵向多孔的棒状ZnO具有更优异的光催化性能,在紫外光照射20min后,对甲基橙的降解率达到100%。通过动力学模型拟合发现,纵向多孔的棒状ZnO具有更大的催化速率常数(0.2942 min~(-1)),是实心ZnO纳米棒催化速率常数(0.1306min~(-1))的2.25倍。     

Effect of textured seeds on the morphology and optical properties of solution- and vapor-grown ZnO nanorod arrays

This paper examines the growth of aligned ZnO nanorod arrays through chemical deposition from solution and the vapor phase. The nanorod alignment is ensured primarily by a thin layer of seeds—zinc oxide nanoparticles produced by decomposing zinc acetate directly on the substrate and aligned with their c axes normal to the substrate surface. The acetate route was used to produce nanorod arrays 1 × 1 mm in dimensions on substrates with photoresist.     

Control of epitaxial growth orientation in ZnO nanorods on c-plane sapphire substrates

This paper presents a study on low temperature hydrothermal growth of ZnO nanorods (NRs) on pre-seeded (0001) sapphire substrates. Prior to hydrothermal growth of ZnO NRs, epitaxial ZnO seeds were grown by metal-organic chemical vapour deposition under various process conditions. Findings show that the majority of ZnO NRs inclined at a specific angle of about 38° to the direction perpendicular to the substrate surface and exhibited a preferential in-plane alignment, besides other NRs growing vertically from the sapphire surface. X-ray diffraction φ-scan measurements reveal that the ZnO nanorods displayed two distinct epitaxial relationships with sapphire which were (0001)_ZnO//(0001)_sapphire and (0001)_ZnO//(101?4)_sapphire, respectively. Reduced lattice mismatch between ZnO and sapphire is responsible for the inclined ZnO NRs growth. The growth direction of ZnO NRs is remarkably dependent on the growth conditions of ZnO seeds and sapphire substrate pre-treatment. The epitaxial orientations of ZnO seeds grown on the sapphire substrate dominate the subsequent ZnO NRs growth and can be controlled through adjusting growth conditions.     

Influence of substrate temperature on ultraviolet emission of ZnO films prepared by ultrasonic spray pyrolysis

ZnO films were deposited on MgO substrates (ZnO/MgO) by ultrasonic spray pyrolysis. Substrate temperature varied from 200 to 350°C. The crystallographic properties and surface morphologies of the ZnO/MgO films were studied by X-ray diffraction and scanning electron microscopy. The properties of photoluminescence (PL) for the films were investigated by dependence of PL spectra on the substrate temperature and the ambient temperature. Ultraviolet (UV) emission peak (3.37 eV) was dominantly detected at 18 K, which sustained at 300 K with a reduced value of the peak energy. The ZnO/MgO films prepared at 350°C showed the strongest UV emission peak at 18 and 300 K among the films in this study.     

Structural and optical properties of ZnO films grown on the AAO templates

Structural and optical properties of ZnO films grown on Al substrate and anodic alumina oxide (AAO) templates by rf magnetron reactive sputtering deposition were investigated using X-ray diffraction (XRD), atomic-force microscope (AFM) and photoluminescence (PL). We found that ZnO thin films on Al substrate show good C-axis orientation, while the orientation of ZnO film on AAO templates is disordered, this due to the fact that the crystalline of ZnO is greatly influenced by surface morphology of substrates. PL measurements show a blue band in the wavelength range of 400–500 nm caused by the interstitial Zn in the ZnO films. The intensity of emission peak of ZnO films deposited on AAO templates increases compared with that on the Al substrate. Combining electrical resistivity and carrier concentration measurements, we found that that the blue emission intensity is consistent with the concentration for the interstitial zinc in the ZnO films.     

Epitaxial growth of ZnO layers using nanorods with high crystalline quality

Epitaxial ZnO films were grown on c-plane sapphire substrates by metal-organic chemical vapor deposition using a ZnO multi-dimensional structure having the sequence of ZnO film/ZnO nanorods/sapphire. The vertically well-aligned one-dimensional ZnO nanorods were grown epitaxially on the sapphire substrate with in-plane alignment under suitable growth conditions and then used as seeds for the subsequent epitaxial ZnO layer. For the transition of the ZnO structures from the nanorods to the film, the growth temperature and working pressure were controlled, while keeping the other conditions fixed. The growth of the ZnO films on the well-aligned ZnO nanorods results in homoepitaxial growth with the identical orientation relationship along the in-plane direction as well as the same c-axis orientation. The microstructural analysis of the multi-dimensional structure and analysis of the microstructural evolution from the one-dimensional nanorods to the two-dimensional film were conducted using transmission electron microscopy.