基于氧化铝模板的有序ZnO纳米棒的合成及光学特性研究

利用高度有序的多孔氧化铝膜作为模板,使用简单的热蒸发Zn粉的方法,成功地制备出高度有序的ZnO纳米棒束,该方法克服了制备有序纳米结构通常需要的催化剂或复杂的合成过程.利用扫描电镜、透射电镜和X射线衍射研究了样品的形貌及其结构特性,其结果表明模板表面所制备的ZnO纳米棒具有更好的有序度和结晶质量,从而推断出模板表面有序ZnO纳米棒的形成应该同模板表面局域化负电荷的存在有关.同Si基片上所形成无序纳米棒的光致发光谱相比,模板表面所形成的有序ZnO纳米棒束具有更强的紫外峰,表明有序的ZnO纳米棒具有更好的结晶质量和光学特性.     

ZnO纳米阵列的可控合成及其场发射特性

采用水热法在PS模板上制备了不同的ZnO纳米阵列,通过控制反应时间得到不同长径比的ZnO纳米阵列,真空场发射测试表明,使用PS模板的ZnO纳米阵列的场发射性能得到改善,主要因为长纳米棒与短纳米管交叉两层的阵列结构导致屏蔽效应减弱。较长反应时间制备的ZnO纳米棒具有较大的长径比,场发射较好。多次重复场发射测试发现,本实验制备的ZnO纳米棒阵列的场发射稳定性不是很好,还需进一步改善。     

纳米ZnO阵列形貌对其光催化降解性能的影响

利用溶液法在不同形貌基片上制备了ZnO纳米棒阵列。通过聚苯乙烯球自组装阵列控制模板基片的形貌,制备出具有周期性结构的ZnO纳米花点阵;进而通过反应离子刻蚀聚苯乙烯球模板,实现了ZnO周期性点阵由纳米花向纳米环的结构转变。以亚甲基蓝水溶液为目标降解物,比较了不同ZnO纳米棒阵列的光降解能力,发现单位基片面积上ZnO纳米棒的有效受光面积是影响ZnO纳米棒阵列光降解能力的重要因素。     

多孔氧化铝表面方便制备纳米-微米ZnO薄膜材料

利用双通多孔阳极氧化铝(AAO)和非双通的AAO(含有Al基底)为模板通过液相沉积法制备了ZnO纳米-微米材料。结果显示在两种模板上面生成ZnO的过程比较相似,ZnO在表面择优生成,随着反应时间延长到72h,生成了比较独特的纳米-微米结构。这样的制备方法为非双通的AAO为模板方便地制备纳米材料提供了一定的依据,制备的ZnO薄膜结构有望可以在传感器,催化剂等领域得到应用。     

模板法制备氧化锌片状晶体

介绍一种制备在001轴方向高度取向生长的纳米片状氧化锌(ZnO)晶体的方法.在一定量的模板剂PEG600存在下,用氢氧化钠溶液调节硫酸锌溶液至一定pH值制得溶胶,然后在180℃下处理此溶胶7h,即可得结晶形态完好的纳米六方片状ZnO.同时讨论了低温近中性水溶液中ZnO晶体在有模板剂存在下的生长习性.     

ZnO纳米棒为模板的TiO2纳米管制备及其场发射性能研究

以水热法生长ZnO纳米棒阵列为模板,利用液相沉积法成功制备了TiO2纳米管阵列,并系统研究了液相沉积液浓度和沉积时间对ZnO纳米棒的溶解情况,以及所制备TiO2纳米管阵列的场发射性能。实验结果表明:硼酸浓度越大、沉积时间越长,对ZnO纳米棒的溶解作用越明显,因而越不利于TiO2纳米管的制备。利用该种方法制备的TiO2纳米管长径比和致密性可通过ZnO纳米棒的水热生长条件来控制,本实验制备的TiO2纳米管具有优异的场发射性能,其开启场强为4.60 V/μm,场增强因子为10239。     

脉冲激光沉积制备ZnO纳米棒的研究进展

综述了脉冲激光沉积法制备ZnO纳米棒的研究进展.介绍了不同制备参数条件下ZnO纳米棒的形貌特征、性质及其生长机理,阐述了利用脉冲激光沉积制备高质量ZnO纳米棒及阵列的条件,为ZnO纳米棒的制备及性质的深入研究提供了有益的参考.     

ZnO单晶堆垒纳米棒的制备与表征

在Au点阵模板上磁控溅射ZnO薄膜,然后在O2气氛下1000℃退火制备了ZnO单晶堆垒纳米棒。采用扫描电子显微镜(SEM)、高分辨透射电子显微镜(HRTEM)、X射线衍射(XRD)和傅立叶变换红外(FTIR)光谱对样品进行分析。结果表明,ZnO纳米棒是由诸多单晶堆垒而成,每个单晶均为六方纤锌矿结构,纳米棒直径在100nm左右。初步探讨了ZnO单晶堆垒纳米棒可能的生长机理。     

Mn掺杂ZnO囊泡结构的制备

通过两步或三步法分别制备两层或三层结构的碳球模板,在溶液中的Zn离子和Mn离子在模板上吸附后再进行煅烧.TEM及SEM显示,煅烧后得到完全复制碳膜板结构的多层Mn掺杂ZnO囊泡.EDS显示Mn在ZnO中的掺杂含量约为1％.样品具有室温铁磁性,饱和磁化率(Ms)及矫顽磁场(Hc)分别为0.032A·m²/kg及0.781kA/m.这种Mn掺杂ZnO纳米囊泡结构使新奇的囊泡结构和ZnO的磁性性能得到了完美的结合.     

针状纳米ZnO制备EP/ZnO复合材料及其力学性能的研究

研究了用热镀锌渣作原料制得的针状纳米ZnO对EP/ZnO复合材料力学性能的影响.结果表明:使用具有空间结构的针状纳米ZnO所制备的环氧树脂复合材料,与普通ZnO所制备的环氧树脂复合材料相比力学性能得到了较大的提高和改善.当纳米ZnO的含量为4％(质量分数)时,材料的力学性能得到了明显改善,其冲击强度提高46.9％,抗拉...     

Preparation and characterization of vanadium-doped ZnO nanoparticles for environmental application

Vanadium-doped ZnO nanoparticles (ZnO:V) were prepared via flame spray pyrolysis (FSP) from a mixed aqueous solution of zinc hydroxide and vanadyl (IV) acetylacetonate. The morphological, structural and optical properties of the ZnO:V photocatalyst were characterized via transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and UV-visible diffused reflection spectrum (DRS). The photocatalytic activity of ZnO:V was evaluated via photocatalytic degradation of methylene blue (MB). The results showed that the hexagonal wurtzite-structured ZnO:V nanoparticles were successfully synthesized via FSP. The morphology of the as-prepared nanoparticles was polyhedral and non-hollow. The average diameter of ZnO:V, which was calculated from BET result, was 11.7 nm when the molar ratio of V/Zn was 0.1. The maximum decomposition of MB by the ZnO:V nanoparticles was 99.4% after 180 min under UV irradiation, whereas the decomposition of MB by the pure ZnO nanoparticles was 96.6%.     

Comparison of zinc oxide nanoparticles and its nano-crystalline particles on the photocatalytic degradation of methylene blue

Comparison of ZnO nanoparticles and its nano-crystalline particles on the photocatalytic degradation of methylene blue was investigated. ZnO nanoparticles and its nano-crystalline particles were synthesized from sprayed droplets of an aqueous zinc nitrate solution by flame spray pyrolysis and spray pyrolysis assisted with an electrical furnace, respectively. ZnO nanoparticles of 20 nm in average diameter and ZnO nano-crystalline particles of 20 nm in the grain size were prepared to compare the photocatalytic activity. The photocatalytic activity of those ZnO particles was evaluated by measuring the degradation of methylene blue in water under the illumination of ultraviolet rays. Effect of the particle morphology, initial concentration of methylene blue, and photocatalyst loading on the degradation of the methylene blue was investigated under the illumination of ultraviolet rays. The photocatalytic degradation capacity of the ZnO nanoparticles was higher than that of the ZnO nano-crystalline particles. The efficiency of photocatalytic degradation of methylene blue increased with increase in photocatalyst loading and decrease in initial concentration regardless of particle morphology.     

Influence of pH on the photocatalytic activity of ZnO nanoparticles

In this study, ZnO nanoparticles were fabricated by co-precipitation method. The synthesized nanoparticles possessed monodispersity with the average size 20–30 nm. Since the industrial effluents may not be at neutral pH, the effect of pH on the rate of degradation is important and need to be considered. In order to investigate the effect of pH on ZnO nanoparticles photocatalytic activity, the photocatalytic degradation of Rose Bengal, Methylene blue, and Bromocresol green dyes, was studied with different pH values. It was observed that the adsorption of the dyes onto ZnO nanoparticles surface is strongly dependent on the pH of the solution which plays an important role in photocatalytic degradation.     

Microwave-assisted silica coating and photocatalytic activities of ZnO nanoparticles

A new and rapid method for silica coating of ZnO nanoparticles by the simple microwave irradiation technique is reported. Silica-coated ZnO nanoparticles were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), CHN elemental analysis and zeta potential measurements. The FT-IR spectra and XPS clearly confirmed the silica coating on ZnO nanoparticles. The results of XPS analysis showed that the elements in the coating at the surface of the ZnO nanoparticles were Zn, O and Si. HR-TEM micrographs revealed a continuous and uniform dense silica coating layer of about 3 nm in thickness on the surface of ZnO nanoparticles. In addition, the silica coating on the ZnO nanoparticles was confirmed by the agreement in the zeta potential of the silica-coated ZnO nanoparticles with that of SiO₂. The results of the photocatalytic degradation of methylene blue (MB) in aqueous solution showed that silica coating effectively reduced the photocatalytic activity of ZnO nanoparticles. Silica-coated ZnO nanoparticles showed excellent UV shielding ability and visible light transparency.     

纳米氧化锌中空柱的制备及其光催化性能的研究

以醋酸锌和氨水为原料,超声法制备出氧化锌中空柱,采用扫描电镜(SEM)、X射线衍射(XRD)、Uv-vis漫反射对纳米ZnO的形貌、结构进行了表征,以有机染料亚甲基蓝溶液为光催化反应模型降解物,考察纳米ZnO的光催化性能。结果表明:制备出的纳米氧化锌呈中空的柱形,长约2～3μm,直径约300nm,壁厚约40nm,结晶良好。当加入纳米ZnO为0.4g/L,光降解时间为75min,对亚甲基蓝溶液的降解率可达到99.08%。     

Interaction and photodegradation characteristics of fluorescein dye in presence of ZnO nanoparticles

The interaction between xanthene dye Fluorescein (Fl) and zinc oxide (ZnO) nanoparticles is investigated under physiological conditions. From the analysis of the steady state and time resolved spectroscopic studies in aqueous solution static mode is found to be responsible in the mechanism of fluorescence quenching of the dye Fl in presence of ZnO. ZnO nanoparticles are used as photocatalyst in order to degrade Fl dye. At pH 7, a maximum degradation efficiency of 44.4% of the dye has been achieved in presence of ZnO as a nanophotocatalyst and the photodegradation follows second-order kinetics.     

Synthesis of [60]fullerene-ZnO nanocomposite under electric furnace and photocatalytic degradation of organic dyes

Zinc oxide (ZnO) nanoparticles were synthesized by a reaction between an aqueous-alcoholic solution of zinc nitrate and sodium hydroxide under ultrasonic irradiation at room temperature. The morphology, optical properties of the ZnO nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis spectroscopy. The [60]fullerene and zinc oxide nanocomposite were synthesized in an electric furnace at 700 degrees C for two hours. The [60]fullerene-ZnO nanocomposite was characterized by XRD, SEM and TEM. In addition, the [60]fullerene-ZnO nanocomposite was investigated as a catalyst in the photocatalytic degradation of organic dyes using UV-vis spectroscopy. The photocatalytic activity of the [60]fullerene-ZnO nanocomposite was compared with that of ZnO nanoparticles, heated ZnO nanoparticles after synthesis, pure [60]fullerene, and heated pure [60]fullerene in organic dyes such as methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) under ultraviolet light at 254 nm.     

Studying the corrosion resistance and hydrolytic degradation of an epoxy coating containing ZnO nanoparticles

Epoxy nanocomposites containing different contents of Nano-ZnO particles were prepared. The nanocomposites were exposed to 3.5 wt% NaCl solution up to 60 days. Mechanical properties of the nanocomposites (before and after exposure to NaCl solution) were studied by dynamic mechanical thermal analysis (DMTA) and nano-indentation techniques. Fourier transform infrared spectroscopy (FTIR) was utilized to investigate hydrolytic degradation of coatings. Corrosion resistance of the composites was studied by an electrochemical impedance spectroscopy (EIS). Results showed that blank sample was severely deteriorated after exposure to corrosive electrolyte. Corrosion resistance of the epoxy coating was significantly improved using nanoparticles. The cross-linking density and indentation hardness of the blank sample were significantly decreased after exposure to corrosive electrolyte. Results showed that nanoparticles could significantly improve coating resistance against hydrolytic degradation. Results revealed that decrease in cross-linking density and indentation hardness of the epoxy coatings containing 3.5 and 5 wt% nanoparticles were not significant. Decrease in adhesion loss was also obtained using nanoparticles.     

Visible light-activated cadmium-doped ZnO nanostructured photocatalyst for the treatment of methylene blue dye

An attempt was made to prepare Cd-doped ZnO photocatalyst for visible light assisted degradation of a textile dye (methylene blue, MB) in aqueous solutions by a traditional sol–gel process. The as-prepared nanoparticles were characterized by X-ray diffraction, UV–vis diffuse reflectance spectroscopy, and photoluminescence spectra techniques. The results showed that the Cd-doped ZnO possess the single-phase hexagonal wurtzite structure. The photocatalytic activity of the nanoparticles under visible light was investigated by measuring the photodegradation of MB in aqueous dispersion. The effects of key operation parameters such as initial dye concentration, catalyst loading as well as initial pH value on the decolorization extents were investigated. The results indicate that the decolorization of the organic molecule followed a pseudo-first-order kinetics according to the Langmuir–Hinshelwood model. Under the optimum operation conditions, approximately 85.0% dye removal was achieved within 3.5 h.     

ZnO/Al_2O_3复合纳米颗粒的制备与表征

为研究ZnO/Al2O3复合纳米颗粒在涂料、化妆品等领域的应用,采用直接沉淀法制备了纳米ZnO,用硫酸铝水解生成的Al2O3对纳米ZnO进行了表面改性。采用IR、TEM、SEM、XRD等手段对改性前后的粉体进行表征。分析结果表明,改性后粉体颗粒的团聚现象减轻。粉体的光催化降解甲基橙的实验研究表明,改性后ZnO粉体的光催化活性明显下降,进一步证明纳米ZnO颗粒表面存在Al2O3的包覆层。