Growth mechanism and photocatalytic evaluation of flower-like ZnO microstructures prepared with SDBS assistance

Flower-like ZnO microstructures were successfully produced using a hydrothermal method employing ZnSO_(4)/(NH_(4))_(2)SO_(4) as a raw material.The effect of the operating parameters of the hydrothermal temperature, OH^(-)/Zn^(2+) molar ratio, time, and amount of dispersant on the phase structure and micromorphology of the ZnO particles were investigated.The synthesis conditions of the flower-like ZnO microstructures were: hydrothermal temperature of 160℃, OH^(-)/Zn^(2+) molar ratio of 5:1, reaction time of 4 h, and 4 mL of dispersant.The flower-like ZnO microstructures were comprised of hexagon-shaped ZnO rods arranged in a radiatively.Degradation experiments of Rhodamine B with the flower-like ZnO microstructures demonstrated a degradation efficiency of 97.6% after 4 h of exposure to sunshine, indicating excellent photocatalytic capacity.The growth mechanism of the flower-like ZnO microstructures was presented.

Flower-like ZnO modified with BiOI nanoparticles as adsorption/catalytic bifunctional hosts for lithium–sulfur batteries

Due to the high specific capacity and energy density, lithium–sulfur battery is regarded as a potential energy storage conversion system. However, the serious shuttle effect and the sluggish electrochemical reaction kinetics impede the practical use of lithium–sulfur battery. In the interests of breaking through the above knotty problems, herein we propose to use the polar flower-like Zn O modified by Bi OI nanoparticles as bifunctional host with catalytic and adsorption ability for polysulfides in lithium–sulfur battery.It can be found that this adsorption/catalytic host integrates the functions of adsorption and mutual catalytic conversion of polysulfides, in which the polar flower-like Zn O can effectively capture the polysulfides through strong polar-polar interaction, simultaneously the BiOI nanoparticles can accelerate the mutual conversion of polysulfides to Li2 S through reducing the activation energy and conversion energy barrier required for the electrochemical reaction. As a result, under a sulfur loading of 2.5 mg cm^(-2), the lithium–sulfur battery with Zn O/Bi OI/CNT/S as cathode reveals a considerable initial specific capacity of1267 mAh g^(-1) at a current density of 0.1 C. Even the current density increased to 1 C, the capacity can reach as 873.4 mAh g^(-1), together with a good capacity retention of 67.1% after 400 cycles. Therefore,after systematically study the positive effects of the flower-like ZnO modified by catalytic BiOI nanoparticles on the adsorption and catalytic conversion of polysulfides, this work provides a new idea for the development and application of high-performance lithium–sulfur batteries.

Structural, Optical and Luminescence Properties of ZnO Thin Films Prepared by Sol-Gel Spin-Coating Method： Effect of Precursor Concentration

Transparent zinc oxide（ZnO） thin films are fabricated by a simple sol-gel spin-coating technique on glass substrates with different solution concentrations（0.3-1.2 M） using zinc acetate dehydrate [Zn（CH_3COO）_2·2H_2O] as precursor and isopropanol and monoethanolamine（MEA） as solvent and stabilizer, respectively. The molar ratio of zinc acetate dehydrate to MEA is 1.0. X-ray diffraction, ultraviolet-visible spectroscopy and photoluminescence spectroscopy are employed to investigate the effect of solution concentration on the structural and optical properties of the ZnO thin films. The obtained results of all thin films are discussed in detail and are compared with other experimental data.

Structure distortion, optical and electrical properties of ZnO thin films co-doped with Al and Sb by sol-gel spin coating

ZnO thin films co-doped with A1 and Sb with different concentrations and a fixed molar ratio of AlCl3 to SbCl3 at 1：2, are prepared by a sol-gel spin-coating method on glass annealed at 550 ℃ for 2 h in air. The x-ray diffraction results confirm that the ZnO thin films co-doped with Al distortion, and the biaxial stresses are 1.03× 10^8. 3.26× 10^8 and Sb are of wurtzite hexagonal ZnO with a very small 5.23 × 10^8, and 6.97× 10^8 Pa, corresponding to those of the ZnO thin films co-doped with Al and Sb in concentrations of 1.5, 3.0, 4.5, 6.0 at% respectively. The optical properties reveal that the ZnO thin films co-doped with Al and Sb have obviously enhanced transmittance in the visible region. The electrical properties show that ZnO thin film co-doped with Al and Sb in a concentration of 1.5 at% has a lowest resistivity of 2.5 Ω·cm.

Growth and Improvement of ZnO Nanostructure Using Aged Solution by Flow Coating Process

ZnO nanostructures were prepared on corning glass substrate by flow coating process with different annealing temperature from 100?C to 600?C. Fresh and two days aged solutions were used to investigate the growth behavior and to evaluate the nanostructure of ZnO. The effect of preparation conditions on the deposition of ZnO nanostructure was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman, and photoluminescence spectroscopy (PL). The results indicated that the solution aging condition and annealing temperature have a strong influence on the morphology and structural properties of the ZnO nanostructure. The solution aged after two days shows the different morphologies compared with the freshly prepared solution.

Preparation and Characterization of ZnO: In Transparent Conductor by Low Cost Dip Coating Technique

Transparent conducting oxide (TCO) based on indium doped zinc oxide films in the nano scale were successfully prepared using combination between dip coating and thermal decomposition process. Structural investigations confirm the polycrystalline ZnO hexagonal wurtzite phase grown along the c-axis with nano crystallite size about 10 nm. Morphology investigation shows that ZnO films consist of fine grains of average size 40 nm. This indicates that each grain contains several crystallites with different orientations. Cross sectional image presents good adhesion of the films with the substrate and the film thickness has been determined. Compositional analysis detects the indium content in the host ZnO matrix, the In/Zn ratio is close to the calculated concentration ratios of the precursor. The optical transmittance shows that the films are transparent in the UV and VIS-IR spectral region and interference fringes were observed to be thickness dependent. Preparation parameters were investigated and optimized such as dipping rate, number of deposition cycles, precursor concentration, annealing process and In/Zn ratio. Optimization process was investigated for low resistivity, high optical spectral window transmission and easy preparation process. Dipping rate in the range 2 - 38 mm/s is the most suitable range for good film quality while dipping rate range 30 - 38 mm/s produces thicker films in lower deposition cycles. The higher dipping rate produces films with lower transparency (milky films) while the small deposition rate rate requires large number of deposition cycles in order to increase the thickness. Besides, the higher dipping rate reflects lower resistivity of the deposited films. Precursor molar concentration was observed to have an essential effect on the film thickness, film quality and transparency. Lower precursor concentration requires also large number of deposition cycles for thickening the films. The higher concentration results also milky films (high scattering process by powder film). Precursor concentrations in the range 0.7 - 0.9 mol/liter were found to be the optimal for better quality and for faster deposition process. The resistivity of the films has been reduced from the range 1.5 - 2.5 kW?cm to the range 100 - 400 W.cm as the molar concentration reaches the range 0.07 - 0.09 mol/liter. The resistivity of films increases from 330 to 1686 .cm as the decomposition temperature increases from 200C to 350C. Annealing at 450C process after completing the decomposition at 200?C results the lowest resistivity with annealing time in the range 1.5 - 2 h. In/Zn percentage in the range 1.5% - 5% produces the lowest electrical resistivity. The absorption edge of the deposited films was observed to be critical affected by the preparation parameters. The band gap change was discussed through the degenerate semiconductors as well as nanostructured semiconducting materials of the energy gap confinement effect. Deposition of TCO based on ZnO:In was optimized depending on all deposition parameters forwide area, the lower cost and good performance TCO films.

Increasing Dye-Sensitized Solar Cell Efficiency by ZnO Spin-Coating of the TiO₂Electrode: Effect of ZnO Amount

This paper is concerned with the improvement of dye-sensitized solar cell (DSSC) efficiency upon ZnO-coating of the TiO2 electrode. Sol-gel ZnO of controlled amount by varying the number of sol drops during spin-coating is shown to increase the DSSC efficiency. The highest efficiency is obtained at a single sol drop with enhancement of 40%, while beyond this amount the efficiency falls down sharply to zero. Based on measured optical absorption spectra of the different dye-loaded electrodes, it is concluded that this amount of ZnO sol corresponds to the thinnest layer that can create the energy barrier to minimize the electron recombination rate without seriously affecting the dye adsorption efficiency of the TiO2 film.

MgO and ZnO Composite Thin Films Using the Spin Coating Method on Microscope Glasses

In this study, a new route to produce pure and composite ZnO-MgO thin films has been presented. In the process the pure ZnO thin films were the starting point, ending up with MgO by doping various percentages (from 0% to 100%) of Mg with the help of sol-gel spin coating technique. The crystal phases in all doping levels have been obtained when the samples annealed at 600℃ for a duration of 6 hours. The X-ray diffraction (XRD) spectra, the scanning electron microscopy (SEM) micrographs and UV-Vis absorption spectra have been performed to elucidate the composed film structures.

ZnO Spin-Coating of TiO₂Photo-Electrodes to Enhance the Efficiency of Associated Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) with ZnO spin-coated TiO2 photo-electrodes are compared to DSSC with a bare TiO2 photo-electrode. It is demonstrated that the deposited ZnO of controlled amount, by varying the precursor concentration in the coating sol, can indeed enhance the performance of the DSSC. The measured power conversion efficiency shows a maximum around the precursor concentration 0.1 M and falls down sharply to 0% beyond this point. The results are interpreted on the basis of two competing factors: At ZnO concentrations less than 0.1 M, the formation of an energy barrier increases the photocurrent by reducing the rate of interfacial back-recombination. At ZnO concentrations greater than 0.1 M, the screening of the TiO2 film by thicker ZnO layers decreases the photocurrent through the reduction of TiO2 dye-adsorption efficiency.

Influence of Sn Low Doping on the Morphological, Structural and Optical Properties of ZnO Films Deposited by Sol Gel Dip-Coating

In this work, Undoped Zinc Oxide (ZnO) and Sndoped Zinc Oxide (ZnO:Sn) films have been deposited by sol-gel dip coating method, where the Sn/Zn atomic ratio was 3% and 5% in the solution. The effects of Sn incorporation on morphological, structural and optical properties of ZnO films were investigated. The Scanning Electron Microscopy (SEM) showed that the morphological surface of the films was affected by Sn low doping. The X-Ray Diffraction (XRD) patterns showed that all films have polycrystalline structures, and the doping incorporation has not lead to substantial changes in the structural characteristics of ZnO films. The crystallite size was calculated using the well-known Scherrer’s formula and found to be in the range of 23 - 40 nm. The measurements from UV-Visible Spectrophotometer (U-Vis) indicated that the highest average optical transmittance in the visible region was related to Undoped ZnO film, then the optical band gap and Urbach energy values of thin films were calculated. The X-Ray Photoelectron Spectroscopy (XPS) has demonstrated that Sn is incorporated in ZnO lattice.

Effects of Nano Pigments on the Corrosion Resistance of Alkyd Coating

Alkyd coatings embedded with nano-TiO2 and nano-ZnO pigments were prepared. The effects of nano pigments on anticorrosion performance of alkyd coatings were investigated using electrochemical impedance spectrum （EIS）. For the sake of comparison, the corrosion protection of alkyd coatings with conventional TiO2 and ZnO was also studied. It was found that nano-TiO2 pigment improved the corrosion resistance as well as the hardness of alkyd coatings. The optimal amount of nano-TiO2 in a colored coating for corrosion resistance was 1%. The viscosities of alkyd coatings with nanometer TiO2 and ZnO and conventional TiO2 and ZnO pigments were measured and the relation between viscosity and anticorrosion performance was discussed.

Carbon-coated ZnO Nanocomposite Microspheres as Anode Materials for Lithium-ion Batteries

The carbon-coated ZnO nanospheres materials have been synthesized via a simple hydrothermal method.The effect of carbon content on the microstructure,morphology and electrochemical performance of the materials was investigated by XRD,Raman spectroscopy,transmission electron microscopy,scanning electron microscopy and electrochemical techniques.Research results show that the spherical ZnO/C material with a carbon cladding content of 10%is very homogeneous and approximately 200 nm in size.The electrochemical performances of the ZnO/C nanospheres as an anode materials are examines.The ZnO/C exhibits better stability than pure ZnO,excellent lithium storage properties as well as improved circulation performance.The Coulomb efficiency of the ZnO/C with 10%carbon coated content reaches 98%.The improvement of electrochemical performance can be attributed to the carbon layer on the ZnO surface.The large volume change of ZnO during the charge-discharge process can be effectively relieved.

Experimental Study of ZnO-Coated Alumina DBD in Atmospheric Pressure Air

An investigation on the discharge characteristic of a dielectric barrier discharge （DBD） device was carried out using bare and ZnO-coated alumina dielectric layer in atmospheric pressure air. Highly conductive ZnO film was first deposited on the alumina surface, and the characteristics of the dielectric barrier discharge were examined and compared. Experimental result shows that discharge behavior was definitely improved in the case of ZnO-coated dielectric barrier discharge. Relevant explanation is offered to describe its discharge physics.

ZnO/Spiro-MeOTAD异质结自驱动光电探测器的制备及性能(特邀)

ZnO具有高稳定性、低成本、宽带隙等优点,被广泛用于光电探测器但响应速度较慢,采用Zn(TFSI)2和CNT∶TiO_(2)作为混合掺杂剂来代替Li-TFSI,以提高Spiro-MeOTAD的稳定性及光电性能,采用旋涂法制备了ZnO/Spiro-MeOTAD异质结构筑光电探测器。ZnO/Spiro-MeOTAD光电探测器在250~600 nm波长范围内,具有良好的自驱动特性。在0 V条件下,ZnO/Spiro-MeOTAD器件在368 nm的入射光照射下具有最高的光电性能,响应度为27.34 mA W^(-1),比探测率为3.62×10^(11)Jones,开关比为2029,上升/下降时间分别为0.71 s/0.55 s,相较于ZnO的光电性能(响应度为17.74 mA·W^(-1),比探测率为5.11×10^(10)Jones,开关比为63.6,上升/下降时间为11.76 s/1.49 s)分别提升提高了1.5倍、7倍、32倍。ZnO/Spiro-MeOTAD器件在550 nm处仍具有明显响应,响应度和比探测率分别为2.48 mA·W^(-1)和3.32×10^(10)Jones,对比ZnO器件提高了248倍和940倍。不同放置时间(1个月)和预处理温度(0~140℃)下光电流的变化,验证了Spiro-MeOTAD加入构筑p-n异质结,不仅可以显著提升ZnO基光电探测器的响应度、开关比和响应速度,同时使得探测器具有良好的稳定性,可以应用于较高温度工作环境。

壳聚糖和纳米ZnO复合涂膜对冬枣黑斑病抗病性的影响

为了研究不同粒径的纳米ZnO与壳聚糖(Chitosan,CTS)复合涂膜对采后冬枣黑斑病的抗病作用及机理,分别对新鲜冬枣进行涂膜处理,再接种链格孢菌,测定冬枣的果实品质指标、抗病物质含量、抗氧化能力以及抗病相关酶活性的变化。结果表明,0.2%≤100 nm纳米ZnO复合1%CTS处理组实验效果最佳,可延缓冬枣果实病斑直径的扩展,抑制呼吸强度上升,降低失重率和转红率;抑制总酚、黄酮等抗氧化物质含量的降低,提高冬枣的还原力和DPPH自由基清除能力,而且超氧化物歧化酶、过氧化氢酶和抗坏血酸过氧化物酶活性也得到了提高。因此,纳米ZnO与CTS复合涂膜处理通过诱导抗病相关酶活性,维持果实细胞膜结构的稳定,进而增强冬枣采后抗病性,从而延缓黑斑病的发生。

溶胶-凝胶法制备ZnO薄膜及表征

采用溶胶 -凝胶法在石英玻璃衬底上使用旋转涂覆技术生长了 Zn O薄膜 .对薄膜的 XRD分析表明 Zn O薄膜为纤锌矿结构并沿 c轴取向生长 .透射光谱表明薄膜的禁带宽度为 3.2 8e V ,与 Zn O体材料的禁带宽度 3.30 e V基本相同 .用光致发光谱分析了经过 5 0 0～ 70 0℃热处理获得的 Zn O薄膜 ,结果表明 Zn O薄膜在室温下有较强的紫外带边发射 ,但当热处理温度高于 70 0℃时 。

纳米TiO_2和ZnO的抗老化性应用研究

利用纳米TiO2和ZnO对聚丙烯材料和建筑外墙涂料进行添加量为0.5%～3%的小量填充改性,结果表明,对聚丙烯改性后,采用GB9344-88所述的塑料氙灯光源曝露试验方法,进行800h人工加速老化试验后色差仅为0.93,变色评级为4/5级,测试样条无粉化;对建筑外墙涂料改性后,涂料的耐候性较原配方提高了2倍,因此,可用无机纳米材料代替传统的有机紫外线吸收剂作为抗老化剂使用。

溶胶-凝胶提拉法制备ZnO薄膜及其性能研究

采用溶胶 凝胶提拉法在石英玻璃衬底上生长了ZnO薄膜。对薄膜的XRD分析表明ZnO薄膜为纤锌矿结构并沿c轴择优取向生长。透射光谱表明薄膜的禁带宽度为 3 2 8eV ,与ZnO体材料的禁带宽度 3 30eV基本相同。用荧光光谱分析了经过 4 0 0～ 6 0 0℃热处理获得的ZnO薄膜 ,结果表明ZnO薄膜在室温下可获得较强的紫外带边发射。适当选择热处理温度可以获得无可见波段发射的ZnO薄膜。

Na_2WO_4-WO_3-ZnO体系熔盐镀钨

对Na2 WO4 WO3 ZnO体系熔盐镀钨工艺进行了详细研究 ,得到了获得金属钨镀层的工艺条件。结果表明 :在空气气氛中 ,当氧化钨的浓度为 1 5%～ 30 %时 ,于 850～ 950℃能得到金属钨镀层且镀层表面平整 ;当其它条件都相同时 ,在铜基体上获得钨镀层比钼基体上所需的温度略高一些 ;扫描电镜照片显示钨镀层与钼基体之间有明显分界面 ,元素线扫描结果证实镀层与钼基体间扩散层厚度仅为 2 .5μm ,基本不形成扩散层 ;不同电流密度下所获得的钨镀层X射线衍射表明镀层中存在织构。

ZnO纳米材料杂化硅丙乳液的合成与性能研究

研究了合成机械稳定性合格的ZnO纳米材料杂化硅丙液的前提条件和合成方法 ;制备了各种稳定性合格的具有核—壳型结构的ZnO纳米材料杂化硅丙乳液 ;利用该纳米杂化乳液制备了耐人工老化达到 170