苯甲酸改性纳米氧化锌的制备及表征

利用苯甲酸对纳米氧化锌进行表面改性,用亲油化度和吸水率表征改性效果,确定其最佳改性工艺为:苯甲酸质量分数为15%,改性温度为100~105℃,改性时间为2 h。通过X射线衍射、红外光谱、透射电镜、沉降实验和接触角测试,对改性前后的样品进行表征。结果表明,苯甲酸对纳米氧化锌的改性属于化学改性,苯甲酸的羧基与纳米氧化锌表面的羟基发生键合反应,从而改变了纳米氧化锌的性能;改性后的纳米氧化锌样品结晶度高,分散性好,疏水性明显提高。     

纳米氧化锌改性胶粉/天然橡胶复合材料的制备及性能

利用纳米氧化锌采用直接混合、球磨分散混合及超声分散混合法对胶粉进行了改性．并在开炼机上制备了纳米氧化锌改性胶粉／天然橡胶复舍材料。利用扫描电镜对纳米氧化锌的分散效果进行了考察，并测试了填充改性胶粉的天然橡胶复合材料的拉伸性能、撕裂强度及耐磨性。结果表明，超声分散混合法得到的试样中纳米氧化锌的分散情况较好，其中采用钛酸酯偶联剂改性的试样的性能最佳，与纳米氧化锌直接混合和添加活性氧化锌的试样相比其拉伸强度分别提高32％和55％，扯断伸长率分别提高7％和22％，撕裂强度分别提高28％和39％．耐磨性分别提高17％和7％。     

表面改性方式对纳米氧化锌紫外吸收性能影响研究

纳米氧化锌是一种重要的无机紫外吸收剂,在应用时需要对其进行表面改性和分散,本文研究了不同的改性方式对纳米氧化锌紫外吸收性能的影响,分析研究了其不同的改性机理.结果表明原位改性是一种较好的改性方式,但对纳米氧化锌的外观形貌产生了影响,主要原因是聚乙二醇作为模板剂和表面活性剂影响了其前驱体氢氧化锌的形貌,而纳米氧化锌粉体表面改性是通过聚乙二醇的空间位阻作用使纳米氧化锌分散程度提高.使用同一种改性剂对纳米氧化锌原位改性和对纳米氧化锌粉体改性,对其紫外吸收性能没有大的影响.     

乙酸乙酯改性纳米氧化锌的制备及表征

利用乙酸乙酯作为改性剂,通过气相法对纳米氧化锌进行改性研究,用亲油化度考察改性效果;优化其改性工艺为:改性时间2h,改性温度120℃,改性剂的添加量为3.25%。通过透射电镜、激光粒度仪、接触角和沉降实验表明,改性后的纳米氧化锌颗粒均匀、团聚明显减弱、疏水性和分散性明显提高。     

ZnO/Al2O3复合纳米颗粒的制备与表征

以硫酸锌和氢氧化钠为原料,采用直接沉淀法制备了纳米氧化锌,并用硫酸铝水解生成的三氧化铝对钠米氧化锌进行了表面改性,并采用IR、TEM、SEM、XRD等手段对改性前后的粉体进行表征研究.TEM和SEM分析结果表明,改性后粉体颗粒的粒径小、团聚现象减轻.此外,进行了粉体的光催化降解甲基橙的实验研究.实验结果表明,改性后ZnO粉体的光催化活性明显下降,这进一步证明了纳米氧化锌颗粒表面存在三氧化二铝的包覆层.     

ZnO/Al2O3复合纳米颗粒的制备与表征

以硫酸锌和氢氧化钠为原料,采用直接沉淀法制备了纳米氧化锌,并用硫酸铝水解生成的三氧化铝对钠米氧化锌进行了表面改性,并采用IR、TEM、SEM、XRD等手段对改性前后的粉体进行表征研究.TEM和SEM分析结果表明,改性后粉体颗粒的粒径小、团聚现象减轻.此外,进行了粉体的光催化降解甲基橙的实验研究.实验结果表明,改性后ZnO粉体的光催化活性明显下降,这进一步证明了纳米氧化锌颗粒表面存在三氧化二铝的包覆层.     

Preparation and characterization of nano-ZnO modified hv acetic ether

利用乙酸乙酯作为改性剂,通过气相法对纳米氧化锌进行改性研究,用亲油化度考察改性效果;优化其改性工艺为:改性时间2h,改性温度120℃,改性剂的添加量为3.25％.通过透射电镜、激光粒度仪、接触角和沉降实验表明,改性后的纳米氧化锌颗粒均匀、团聚明显减弱、疏水性和分散性明显提高.     

纳米氧化锌表面包覆改性及其表征

采用液相沉积法对纳米氧化锌进行表面包覆SiO2和SiO2/Al2O3改性,并用XRD、TEM、TG-DSC对其表面结构进行了表征,借助Zeta电位测定仪、静态沉降实验等分析手段考察了改性前后纳米氧化锌在水体系中的分散稳定性.结果表明,在ZnO表面形成的包覆物是以非晶态形式存在的,通过表面包覆SiO2和SiO2/Al2O3改性后明显提高了氧化锌的表面羟基含量,有效改变了氧化锌的等电点,显著提高了纳米氧化锌在水中的分散稳定性.     

纳米氧化锌-煅烧高岭土复合材料的制备

以煅烧高岭土和纳米氧化锌为主要原料,用水解沉淀法在煅烧高岭土表面包覆纳米氧化锌,制备一种无机复合型抗紫外材料;采用分光光度计分别测定在波长325、350、375、400nm紫外光下复合材料的紫外光吸光度。结果表明:反应温度、氧化锌包覆量、改性时间、改性剂滴加速度、矿浆浓度、煅烧温度等对纳米氧化锌-煅烧高岭土复合粉体材料的紫外光吸收性能有重要影响。在制备条件为:氧化锌包覆量为8%、反应温度为90℃、改性时间为10min、改性剂滴加速度为3mL/min、矿浆中m(水)∶m(煅烧高岭土)=10∶1、煅烧温度为400℃时,所制备的纳米氧化锌-煅烧高岭土复合粉体材料的紫外光吸收性能较好。     

纳米3Y—TZP粉体的表面改性研究

用月桂酸对纳米3Y—TZP粉体进行表面改性,实验结果表明,改性最佳工艺为：月硅酸用量10％、改性时间75min、改性温度60％。经表面改性的粉体,由引起团聚的强极性多羟基表面结构变为非极性有机表层结构,粉体间作用力减小,硬团聚消失,大幅度提高了陶瓷体的烧结性能。     

Blue luminescence from carbon modified ZnO nanoparticles

In this work, a novel method was used to prepare carbon modified ZnO nanoparticles. The nanoparticles were coated with a layer of poly(methyl methacrylate) by γ radiation firstly, and then the coated nanoparticles were annealed in air. The polymer was burned and carbon was left on the surface of ZnO nanoparticles. A stable blue luminescence peak (~420 nm) can be observed for the carbon modified ZnO nanoparticles. The carbon modified ZnO nanoparticles were also investigated by X-ray photoelectron spectroscopy. The origin of the blue emission was discussed. The blue PL is related to the left carbon. This novel method also can be used to prepare other carbon modified nanoparticles.     

基于PEG修饰的ZnO量子点光学特性研究

采用溶胶-凝胶法制备了ZnO量子点, 并采用有机高分子试剂PEG(聚乙二醇, M_w=2000)对其表面进行修饰。借助X射线衍射分析、傅立叶红外光谱、光致发光谱和透射显微镜等测试方法, 研究了PEG表面修饰对ZnO量子点结构和光学性能的影响规律。研究表明, 混合加入的PEG聚合物能够成功地包覆在ZnO量子点表面, 但没有改变量子点的晶体结构, 经PEG表面修饰后的ZnO量子点尺寸变小, 稳定性增强, 分散更均匀。同时经PEG修饰的ZnO量子点在400~500 nm波长区域缺陷态发射峰明显减弱, 表明采用PEG来改善ZnO量子点表面缺陷结构具有良好效果。     

Influence of surface modification by 2-aminothiophenol on optoelectronics properties of ZnO nanoparticles

In this study, a precipitation method was used to synthesise ZnO nanoparticles using suitable precursors. An efficient surface modification method was proposed in order to reduce the agglomeration among synthesised small sized ZnO nanoparticles using 2-aminothiophenol as a capping agent. This article briefly investigated the effects of capping agent like 2-aminothiophenol on the optoelectronic properties of ZnO nanoparticles. The modified effectivity of 2-aminothiophenol has been examined on the nanosized ZnO nanoparticle for fluorescence and UV–visible (UV–vis) studies. The mechanism was studied for ZnO nanoparticles light emitting capability under different conditions. By facilitating the capping of ZnO with 2-aminothiophenol, fluorescence emission of the surface defects vanishes and ultraviolet (UV) emission increases. Surface capping by 2-aminothiophenol effectively covers most of the surface defects of ZnO and results in quenching of the visible region. The UV–vis absorption spectra of modified ZnO nanoparticles has been influenced by modified ZnO nanoparticles as a result of surface modification; where marked blue shift in absorption edge results. By surface modification of ZnO nanoparticles, change in optoelectronics properties has opened the new scope and possibilities to explore and fine tune the optical character of the modified ZnO for various optoelectronics applications such as UV laser.     

Use of silane coupling agent for surface modification of zinc oxide as inorganic filler and preparation of poly(amide-imide)/zinc oxide nanocomposite containing phenylalanine moieties

A series of novel poly(amide?Cimide)/ZnO nanocomposites with modified ZnO nanoparticles contents was prepared by ultrasonic irradiation. For this purpose, surface of ZnO nanoparticle was modified with $\boldsymbol\gamma$ -aminopropyltriethoxysilane as a coupling agent. Then the effect of surface modification on dispersion of nanoparticles, thermal stability and UV absorption property of the obtained nanocomposites were investigated. The resulting novel nanocomposites were characterized by several techniques. Field emission scanning electron microscopy and transmission electron microscopy analyses of the nanocomposites were performed in order to study the dispersion of nanofillers in the polymer matrix. According to thermogravimetry analysis results, the addition of ZnO nanoparticles improved thermal stability of the obtained nanocomposites. Since the resulting nanocomposites contain phenylalanine amino acid and ZnO, they are expected to be biocompatible as well as biodegradable.     

Modification of ZnO nanorods through Au nanoparticles surface coating for dye-sensitized solar cells applications

Dye-sensitized solar cells (DSSC) based on ZnO nanorods were fabricated and modified through the addition of Au nanoparticles. The as-synthesized ZnO nanorods were well-dispersed and of high crystallinity quality leading to a high cell efficiency of 5.2%. On the other hand, thick layer of Au nanoparticles aggregation may have led to distortion of plasmonic effect. Also, the addition of Au nanoparticles have effectively decreased the surface area of ZnO nanorods with direct contact to the dye molecules, resulting in a lower amount of adhered dye molecules to convert sunlight. The electrons generated by the photo-absorption through thick aggregated Au nanoparticles layer may have a lower injection rate to ZnO nanorods as compared to those absorbed by the dye.     

Highly enhanced acetone sensing performances of porous and single crystalline ZnO nanosheets: high percentage of exposed (100) facets working together with surface modification with Pd nanoparticles

Porous and single crystalline ZnO nanosheets, which were synthesized by annealing hydrozincite Zn(5)(CO(3))(2)(OH)(6) nanoplates produced with a water/ethylene glycol solvothermal method, are used as building blocks to construct functional Pd-ZnO nanoarchitectures together with Pd nanoparticles based on a self-assembly approach. Chemical sensing performances of the ZnO nanosheets were investigated carefully before and after their surface modification with Pd nanoparticles. It was found that the chemical sensors made with porous ZnO nanosheets exhibit high selectivity and quick response for detecting acetone, because of the 2D ZnO nanocrystals exposed in (100) facets at high percentage. The performances of the acetone sensors can be further improved dramatically, after the surfaces of ZnO nanosheets are modified with Pd nanoparticles. Novel acetone sensors with enhanced response, selectivity and stability have been fabricated successfully by using nanoarchitectures consisting of ZnO nanosheets and Pd nanoparticles.     

Structure and Optical Behavior of Nanocomposite Hybrid Films of Well Monodispersed ZnO Nanoparticles into Poly （vinylpyrrolidone）

We fabricated an inorganic-polymeric photoluminescent thin film based on ZnO nanoparticles, which were grown directly in the poly（vinylpyrrolidone） （PVP） matrix. The microstructure, composition, thermal stability, and the temperature-dependent photoluminescence of the thin film were investigated. X-ray diffraction （XRD） and transmission electron microscopy （TEM） results indicated that all the ZnO nanoparticles with a polycrys talline hexagonal wurzite structure were well separated from each other and were dispersed in the polymeric matrix homogeneously and randomly. Raman spectrum （Raman） showed a typical resonant multi-phonon process within the hybrid thin film. The shifts of infrared bands for PVP in the hybrid film should be attributed to strong coulombic interaction between ZnO and polymeric matrix. The stability of the hybrid film and the effect of the perturbation of ZnO on the stability were determined by means of the thermogravimetric analysis （TG） and differential thermal analysis （DTA）. The ultraviolet-visible adsorption （UV-vis） showed distinct excitonic features. The photoluminescent spectrum （PL） of the ZnO nanoparticles modified by PVP molecules showed markedly enhanced ultraviolet emission and significantly reduced green emission, which was due to the Perfect surface passivation of ZnO nanoparticles. Temperature dependent photoluminescent spectrum studies suggested that the ultraviolet emission was associated with bound exciton recombination.     

Zinc oxide incorporating iron nanoparticles with improved conductance and capacitance properties

Iron nanoparticles were incorporated into zinc oxide powders by an in situ dispersion method. The products were fully characterized by X-ray diffractometry, diffuse reflectance, FTIR spectrophotometry and complex impedance spectroscopy. The XRD patterns agreed with that of the ZnO typical wurtzite structure, the sharp diffraction peaks indicating good crystallinity of ZnO and ZnO-Fe nanoparticles. The average particle size determined by the Scherrer equation showed an increase from 20 to 25 nm for ZnO and ZnO-Fe respectively. The UV peak positions of the modified samples shifted to a longer wavelength compared to pure ZnO, providing evidence of changes in the acceptor level induced by iron nanoparticles. The optical band gap of the samples was found to be 3.14 eV for ZnO and 3.04 eV for ZnO-Fe. The electrical properties were investigated between 273 and 413 K, at several frequencies. Besides, a detailed analysis of the impedance spectrum showed an appreciable improvement of the conductivity due to the addition of iron nanoparticles. The incorporation of Fe-NPs appears to be responsible for conductance variations, charge transfer and capacitance improvement. The above properties make these materials to be regarded as very promising electrode materials for high-efficiency energy storage.     

Synthesis of relatively monodisperse ZnO nanocrystals from a precursor zinc 2,4-pentanedionate

Monodisperse ZnO nanoparticles were successfully prepared through the decomposition of zinc acetylacetonate precursor in oleylamine. The samples were characterized by transmission electron microscope, X-ray diffraction and infrared spectroscopy. The particle size and morphology could be modified through tuning the reaction temperature, reaction period and concentration of zinc acetylacetonate. The grain size of monodisperse ZnO could be obtained at 205 and 300 °C for 1 h with 1:100 molar ratio of acetylacetonate and oleylamine, respectively. The average grain size of ZnO nanoparticles increased and the shape of ZnO particles varied with the reaction period prolonging or reaction temperature increasing. Some ZnO particles had self-aggregated into a belt using a solution of 1:10 molar ratio of zinc acetylacetonate and oleylamine at 250 °C for 1 h. The oleylamine plays an important role in preventing aggregation of ZnO nanoparticles.     

Sonochemical synthesis and photocatalytic property of zinc oxide nanoparticles doped with magnesium(II)

Mg-doped ZnO nanoparticles were successfully synthesized by sonochemical method. The products were characterized by scan electron microscopy (SEM) and X-ray powder diffraction (XRD). SEM images revealed that ZnO doped with Mg(II) nanoparticles and ZnO nanoparticles synthesized by the same strategy all had spherical topography. XRD patterns showed that the doped nanoparticles had the same crystals structures as the pure ZnO nanoparticles. The Mg-doped ZnO nanoparticles had larger lattice volume than the un-doped nanoparticles. X-ray photoelectron spectroscopy (XPS) not only demonstrated the moral ratio of Mg and Zn element on the surface of nanoparticles, but their valence in nanoparticles as well. The Mg-doped ZnO nanoparticles presented good properties in photocatalyst compared with pure ZnO nanoparticles.