Effect of seeded substrates on hydrothermally grown ZnO nanorods

We report a study on the effect of seeding on glass substrates with zinc oxide nanocrystallites towards the hydrothermal growth of ZnO nanorods from a zinc nitrate hexahydrate and hexamethylenetetramine solution at 95 °C. The seeding was done with pre-synthesized ZnO nanoparticles in isopropanol with diameters of about 6–7 nm as well as the direct growth of ZnO nanocrystallites on the substrates by the hydrolysis of pre-deposited zinc acetate film. The nanorods grown on ZnO nanoparticle seeds show uniform dimensions throughout the substrate but were not homogenously aligned vertically from the substrate and appeared like nanoflowers with nanorod petals. Nanorods grown from the crystallites formed in situ on the substrates displayed wide variations in dimension depending upon the preheating and annealing conditions. Annealing the seed crystals below 350 °C led to scattered growth directions whereupon preferential orientation of the nanorods perpendicular to the substrates was observed. High surface to volume ratio which is vital for gas sensing applications can be achieved by this simple hydrothermal growth of nanorods and the rod height and rod morphology can be controlled through the growth parameters.     

A facile approach to hexagonal ZnO nanorod assembly

Nanocrystalline ZnO nanorods were successfully grown by ultrasonication using an acidic ethanolic zinc acetate precursor solution followed by a flow coating process and annealing at 600 °C. The ZnO nanorods obtained were hexagonal in shape and showed a high degree of uniformity in size and distribution. These samples were characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Raman spectrophotometry and the results are discussed. This approach appears to be the easiest way to fabricate bulk ZnO nanorods.     

Water-based wet chemical synthesis of (doped) ZnO nanostructures

Looking at its vast range of applications, nanostructured ZnO can be considered as a key technological material. Simple and ecological production techniques for this and other nanostructured materials can boost the detection of their unusual properties. In this context water-based wet chemical synthesis routes for nanostructured ZnO are explored in this study. The advantages and disadvantages of controlled double-jet precipitation, microemulsion preparation, hydrothermal synthesis and an aqueous solution-gel route are described for the formation of (doped) ZnO nanoparticles. The influence of the synthesis parameters on the particle size, size distribution and degree of agglomeration of the particles is reported. Thin films are prepared by chemical solution deposition from aqueous solution. The heat treatment profile and the precursor composition are seen to largely control the density, the grain size and the degree of preferential c-axis orientation.     

Effect of γ-irradiation on the growth of ZnO nanorod films for photocatalytic disinfection of contaminated water

The growth of ZnO nanorods on a flat substrate containing γ-irradiated seeds and their ability to photocatalytically eliminate bacteria in water were studied. The seed layer was obtained, by the spray pyrolysis technique, from zinc acetate solutions γ-irradiated within the range from 0 to 100 kGy. Subsequently, to grow the rods, the seeds were immersed in a basic solution of zinc nitrate maintained at 90 °C. The rate of crystal growth on the seed layer during the thermal bath treatment was kept constant. The resulting materials were characterized morphologically by scanning electron and atomic force microscopies; X-ray diffraction was used to study their morphology and structure and ultraviolet-visible spectroscopy to determine their absorbance. The obtained seed films were morphologically dependent on the radiation dose and this was correlated with the ZnO nanorod films which presented a texture in the (002) direction perpendicular to the substrate. The rods have a hexagonal mean cross section between 20 and 140 nm. Using these rods, the photocatalytic degradation of Escherichia coli bacteria in water was studied; a positive influence of the crystalline texture on the degradation rate was observed.     

Controlled growth of well-aligned ZnO nanorod array using a novel solution method

A simple method of synthesizing nanomaterials and the ability to control the size and position of them are crucial for fabricating nanodevices. In this work, we developed a novel ammonia aqueous solution method for growing well-aligned ZnO nanorod arrays on a silicon substrate. For ZnO nanorod growth, a thin zinc metal seed layer was deposited on a silicon substrate by thermal evaporation. Uniform ZnO nanorods were grown on the zinc-coated silicon substrate in aqueous solution containing zinc nitrate and ammonia water. The growth temperature was as low as 60-90 degrees C and a 4-in. wafer size scale up was possible. The morphology of a zinc metal seed layer, pH, growth temperature, and concentration of zinc salt in aqueous solution were important parameters to determine growth characteristics such as average diameters and lengths of ZnO nanorods. We could demonstrate the discrete controlled growth of ZnO nanorods using sequential, tailored growth steps. By combining our novel solution method and general photolithography, we selectively grew ZnO nanorod arrays on a patterned silicon substrate. Our concepts on controlled ZnO nanorod growth using a simple solution method would be applicable for various nanodevice fabrications.     

Hydrothermal Synthesis and Field Enhancement Behavior of ZnO Nanorods Pattern

We provide a new way to prepare ZnO nanorods pattern from the solution composed of hexamethylenetetramine (HMT) and Zn(NO₃)₂. The substrate is ITO substrate covered by well ordered Au islands. Since Au and the underneath ITO substrate have two different nucleation rates in the initial stage of heterogeneous nucleation process, the subsequent ZnO growth on the quick nucleating area takes place under diffusion control and is able to confine the synthesis of ZnO nanorods to specific locations. The concentrations of zinc nitrate and HMT are well adjusted to show the possibility of the new route for the patterning of the ZnO nanorods. Furthermore, the nanorods pattern was characterized by X-ray diffraction and photoluminescence and the performance of field emission property from ZnO nanorod patterns was investigated. The ZnO nanorods pattern with a good alignment also shows a good field enhancement behavior with a high value of the field enhancement factor.     

Growing ZnO crystals on magnetite nanoparticles

We report herein on the oriented growth of ZnO crystals on magnetite nanoparticles. The ZnO crystals were grown by hydrolyzing a supersaturated aqueous solution of zinc nitrate. The seeds for the growth were magnetite nanoparticles with a diameter of 5.7 nm and a narrow size distribution. Hollowed ZnO hexagons of 0.15 microm width and 0.5 microm length filled with Fe(3)O(4) particles were obtained. HR-TEM (high-resolution transmission electron microscopy) and selected-area EDS (energy-dispersive spectroscopy) show that the nanoparticles are homogenously spread in the ZnO tubes. Zeta potential measurements were employed to understand the relationship between the nanoparticles and the oriented growth of the ZnO crystals. The results show that the surfactants induced the directional growth of the ZnO crystals.     

Aqueous solution fabrication of large-scale arrayed obelisk-like zinc oxide nanorods with high efficiency

Two-dimensional (2D) arrays of obelisk-like zinc oxide nanorods were successfully synthesized with high efficiency on quartz and glass substrate on a large scale through a simple aqueous solution deposition method with zinc nitrate, ammonia, and ammonium chloride as the precursors. Characterized by XRD, EDS, TEM and SEM, the as-grown zinc oxide rods had a single crystalline obelisk-like hexagonal wurtzite structure with diameters of about 300-400 nm and length up to 5 μm. Both XRD and SEM studies revealed the orientation of ZnO rods, and the orientation of ZnO rods can be controlled easily by temperature, pH of the reaction system and the concentration of reactants.     

直接沉积法制备棒状ZnO

在溶液体系中90 ℃下, 以三乙醇胺与醋酸锌为反应试剂, 用直接沉积法合成了微米及纳米尺寸的棒状ZnO粒子, 并对粒子进行了透射电镜(TEM)、X射线衍射(XRD)、热重(TG)和差热扫描量热分析(DSC)等表征. 通过晶体的成核和生长理论初步解释了棒状ZnO粒子的形成过程.     

一种在固体基底上制备高度取向氧化锌纳米棒的新方法

采用廉价、低温的方法，在修饰过ZnO纳米粒子膜的ITO基底上成功制备出具有 高长径比、高度取向的ZnO纳米棒阵列，用扫描电子显微镜(SEM)，X射线衍射(XRD) ，高分辨透射电子显微镜(HRTEM)以及拉曼光谱对制备出的ZnO纳米棒的结构和形貌 进行了表征，测试结果表明，ZnO纳米棒是单晶，属于六方晶系，与基底直，上仍 沿(001)晶面择优生长的特征，并且ZnO纳米棒基本上无氧空位的存在，统计结果显 示，水热反应2h后90%以上的ZnO纳米棒直径为120～190nm，长度为4μm     

Photochemical reduction of sulfur in the presence of ZnO nanoparticles in ethanol

The photochemical reduction of sulfur by the action of ZnO nanoparticles of various shapes and sizes under the conditions of stationary and pulsed photoexcitation was studied. The mechanism of this process was proved; the main route to the formation of the reaction product zinc sulfide is reduction of the sulfur by photochemically produced metallic zinc. It was demonstrated that ordered agglomerates of ZnS nanoparticles in the form of nanotubes and nanorods are formed in the systems based on ZnO nanorods.     

Pt纳米花/ZnO复合阵列的制备及对甲醇氧化催化的研究

利用调控ZnO纳米棒阵列的疏水、亲水性,由电化学方法制备了Pt纳米花/ZnO(PtNF/ZnO)复合阵列.该复合阵列排列规则、尺寸均一、方向一致.每一根ZnO纳米棒的顶端都覆盖着由Pt纳米颗粒构成的Pt纳米花,具有大的比表面积.与以亲水性的ZnO纳米棒制得的覆盖Pt纳米颗粒的ZnO复合阵列(PtNP/ZnO)以及单独的Pt颗粒相比,PtNF/ZnO复合阵列对甲醇氧化具有更高的电化学催化活性.     

ZnO nanoparticles as chain elasticity reducer and structural elasticity enhancer: Correlating the degradating role and localization of ZnO with the morphological and mechanical properties of PLA/PP/ZnO nanocomposite

The main purpose of this study was to investigate the effect of zinc oxide (ZnO) nanoparticles on the morphological, mechanical, thermal, and rheological properties of PLA/PP blend. In this regard, nanocomposites containing 1, 3, and 5 wt% of ZnO nanoparticles were prepared by melt mixing. In addition, three different mixing procedures were adopted to study their effects on the microstructure of nanocomposites. The rheological behaviors demonstrated a higher elasticity and less compatibility for two phases in the case of nanocomposites containing nanoparticles in harmony with the morphological observations. Accordingly, it was correlated to the elasticity originating from the interphase, anticipated coalescence of dispersed particles as a result of degradation of PLA chains triggered by ZnO nanoparticles (ZnO‐NPs) and also agglomeration of ZnO‐NPs depending on the content of nanoparticles and chosen mixing procedure. It was also found that mixing method puts a remarkable influence on the microstructure and rheological behavior of nanocomposites. Results of mechanical characterizations and thermogravimetric analysis (TGA) also confirmed the degradation induced by ZnO nanoparticles.     

纳米氧化锌的标准摩尔生成焓

采用微乳液-水热辅助法合成了尺寸、形貌均匀的ZnO纳米棒,其长度约400 nm,直径约50 nm。基于将纳米ZnO与块体ZnO的标准摩尔生成焓相关联,依据热力学势函数法设计热化学循环,获得了纳米ZnO与块体ZnO标准摩尔生成焓的关系。结合微量热技术求算出了下所制备的ZnO纳米棒在298.15 K下的标准摩尔生成焓为(-331.70±0.42)kJ.mol-1。     

Water assisted growth of C₆₀ rods and tubes by liquid-liquid interfacial precipitation method

C?? nanorods with hexagonal cross sections are grown using a static liquid-liquid interfacial precipitation method in a system of C??/m-dichlorobenzene solution and ethanol. Adding water to the ethanol phase leads instead to C?? tubes where both length and diameter of the C?? tubes can be controlled by the water content in the ethanol. Based on our observations we find that the diameter of the rods/tubes strongly depends on the nucleation step. We propose a liquid-liquid interface growth model of C?? rods and tubes based on the diffusion rate of the good C?? containing solvent into the poor solvent as well as on the size of the crystal seeds formed at the interface between the two solvents. The grown rods and tubes exhibit a hexagonal solvate crystal structure with m-dichlorobenzene solvent molecules incorporated into the crystal structure, independent of the water content. An annealing step at 200 °C at a pressure < 1 kPa transforms the grown structures into a solvent-free face centered cubic structure. Both the hexagonal and the face centered cubic structures are very stable and neither morphology nor structure shows any signs of degradation after three months of storage.     

溶剂热法制备六角锥形ZnO及其光致发光性能

通过乙酸锌和醇溶液反应得到了六角锥形纳米ZnO颗粒, 反应过程中不使用碱溶液和表面活性剂. 利用透射电子显微镜(TEM)、选区电子衍射(SAED)及扫描电子显微镜(SEM)对其形貌和结构进行了表征分析. 结果表明, 此方法制备的ZnO颗粒为单晶, 而且六角锥形ZnO的室温光致发光谱(PL)在378 nm处显示出了单纯的紫外发射峰, 而不是通常报道的可见光区发射, 这也预示着这种特殊结构的纳米ZnO将会成为一种具有良好应用前景的光学材料.     

UV-assisted synthesis of reduced graphene oxide–ZnO nanorod composites immobilized on Zn foil with enhanced photocatalytic performance

Research on Chemical Intermediates - ZnO nanorods were hydrothermally grown on Zn foil in an alkaline solution and the immobilized nanorods were subsequently hybridized with reduced graphene oxide...     

Controlled one-step fabrication of highly oriented ZnO nanoneedle/nanorods arrays at near room temperature

Highly oriented ZnO nanoneedle/nanorods arrays have been fabricated by direct oxidation of zinc foil in alkaline zincate ion solution at near room temperature (20 degrees C for nanoneedles, 30 degrees C for nanorods).     

梨形核壳结构氧化锌/银亚微米球的制备、表征及光学性能

利用亚锡离子还原银离子生成的金属银沉积在合成的梨形氧化锌表面作为晶种,进一步生长银纳米粒子,制备了梨形的、核壳结构的、单分散的氧化锌/银亚微米球。利用X射线衍射、透射电镜、能量色散X射线谱、紫外可见吸收谱及光致发光谱对所制备样品的形貌、微观结构、组成和光学性能进行了表征。结果表明:(1)样品是由梨形亚微米氧化锌核和银纳米颗粒壳组成;(2)在氧化锌表面的银纳米粒子作为光激发产生的电子捕获剂提高了光产生的载流子的分离效率,在能量没有改变的情况下减少了紫外发射光的强度,淬灭了可见发射光。     

氨水溶液制备ZnO纳米晶阵列的研究

以氨水和硝酸锌为前躯体，采用低温水溶液法在涂敷ZnO晶种层的玻璃衬底上外延生长了ZnO纳米棒晶阵列。应用SEM、TEM、SAED和XRD表征了ZnO纳米晶的形貌和结构。讨论了该组成体系水溶液法纳米棒外延生长的机理及其对棒晶形貌的影响。通过对水溶液pH值的原位二次调整，制备出了ZnO纳米管和表面绒毛状的棒晶阵列，基于生长机理探讨了它们的形成原因，为实现不同形貌ZnO纳米晶阵列的优化控制提供了可能的技术途径。结果表明，不同形貌的ZnO均属沿c轴择优取向的六方纤锌矿结构。