不同醇溶剂中氧化锌纳米晶的可控制备

采用液相直接沉淀法,以醋酸锌和氢氧化钠为原料,在醇溶剂体系中成功制备出不同形貌的ZnO纳米晶,使用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和紫外-可见分光光度计(UV-vis)等检测方法对样品进行表征.结果表明,制备的ZnO均为六方纤锌矿结构,形貌受到溶剂种类、反应温度和反应时间等因素影响;在乙醇溶剂中,通过反应温度和反应时间控制可得到分散均匀、形貌均一纳米颗粒或纳米棒,并对不同形貌ZnO的生长机理进行了初步讨论.     

Trioctylphosphine as Both Solvent and Stabilizer to Synthesize CdS Nanorods

High quality CdS nanorods are synthesized reproducibly with cadmium acetate and sulfur as precursors in trioctylphosphine solution. The morphology, crystalline form and phase composition of CdS nanorods are characterized by transmission electron microscopy (TEM), high-resolution TEM and X-ray diffraction (XRD). CdS nanorods obtained are uniform with an aspect ratio of about 5:1 and in a wurtzite structure. The influence of reaction conditions on the growth of CdS nanorods demonstrates that low precursor concentration and high reaction temperature (260 °C) are favorable for the formation of uniform CdS nanorods with 85.3% of product yield.     

针状ZnO的纳米纤维素诱导制备及光催化性能

以纳米纤维素（NCC）为形貌诱导剂,乙酸锌为反应前驱物,采用水热法合成针状ZnO。通过X射线衍射仪（XRD）、扫描电子显微镜（SEM）和能量色散X射线光谱仪（EDS）对ZnO的形貌、微观结构、结晶特性进行了表征,并探讨了其形成机理及光催化降解性能。结果表明水热条件下,NCC能诱导ZnO在其表面沉积和生长,可形成直径260nm、长度10μm的针状结构,诱导制备的针状ZnO室温下2h内对孔雀绿的紫外光降解效率为88.5%。针状ZnO在光催化剂等领域具有潜在应用价值。     

Growth of Nanograins in Electrospun ZnO Nanofibers

ZnO nanofibers were synthesized using an electrospinning method with polyvinyl alcohol and zinc acetate as precursor materials. The effects of the processing parameters on the microstructure of the synthesized ZnO nanofibers were investigated. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy showed that the ZnO nanofibers were distributed uniformly over the Si substrates and had a polycrystalline nature. Individual nanofibers consisted of nanograins. Interestingly, the nanograins coalesced and grew under higher calcination temperatures and longer calcination times. The activation energy for grain-growth was estimated to be 13.126 kJ/mol, and the dominant growth mechanism was most likely to be related to lattice diffusion in pore control mode.     

Hot pressing sintering of zinc sulfide microsphere decorated with nanorods synthesized by the simple refluxing method

A zinc sulfide microsphere decorated with nanorods was synthesized using the refluxing method. Then, the as-obtained ZnS nanostructures were consolidated via the hot pressing (HP) technique. X-ray diffraction, Fourier transforms infrared spectroscopy, high-resolution transmission electron microscopy, field emission scanning electron microscopy (FESEM), diffuse reflectance spectroscopy, and X-ray mapping analyzes were used to characterize the ZnS sample. The effects of various factors such as pH, temperature, and reaction time were investigated on the morphology and particle size of ZnS nanostructures. The formation of sphalerite phase of ZnS nanoparticles was confirmed by the XRD analysis. FESEM also revealed that ZnS nanostructures with the molar ratio 1:1.3 (zinc: sulfur) had a spherical morphology decorated with sulfur nanorods. The ZnS nanostructures were consolidated by hot pressing technique at 860 °C for 2h under vacuum atmosphere. XRD analysis indicated that the sintered ceramic had a sphalerite phase. FESEM study demonstrated that ZnS ceramic had a grain size diameter within the range of 1–3 μm.     

水热合成六方柱状氧化锌及其光催化性能研究

以二水醋酸锌和六次甲基四胺为原料,采用温和水热法制备了六方柱状ZnO。采用X射线衍射(XRD)、扫描电镜(SEM)和紫外可见光谱对其物相、形貌和光催化性能进行了分析,着重研究了不同的反应条件对ZnO形貌的影响,探讨了六方柱状ZnO的形成机理。结果表明:溶液浓度、pH值、反应温度和反应时间对生成晶体的形貌和晶体质量都会产生影响。制备结晶良好的ZnO的最佳反应条件为:反应液浓度为0.57mol/L,pH值为6.0,反应温度为97℃,反应时间为16h。六方柱状ZnO晶体的形成机理是在一定的水热条件下,醋酸锌与六次甲基四胺水解后形成晶核,由于(0001)晶面的生长速率大于其它晶面,以及(0001)晶面易俘获原子,使得成核后的ZnO沿(0001)面定向生长,最终形成六方柱状结构。     

Preparation and antibacterial properties of titanium-doped ZnO from different zinc salts

To research the relationship of micro-structures and antibacterial properties of the titanium-doped ZnO powders and probe their antibacterial mechanism, titanium-doped ZnO powders with different shapes and sizes were prepared from different zinc salts by alcohothermal method. The ZnO powders were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED), and the antibacterial activities of titanium-doped ZnO powders on Escherichia coli and Staphylococcus aureus were evaluated. Furthermore, the tested strains were characterized by SEM, and the electrical conductance variation trend of the bacterial suspension was characterized. The results indicate that the morphologies of the powders are different due to preparation from different zinc salts. The XRD results manifest that the samples synthesized from zinc acetate, zinc nitrate, and zinc chloride are zincite ZnO, and the sample synthesized from zinc sulfate is the mixture of ZnO, ZnTiO₃, and ZnSO₄ · 3Zn (OH)₂ crystal. UV-vis spectra show that the absorption edges of the titanium-doped ZnO powders are red shifted to more than 400 nm which are prepared from zinc acetate, zinc nitrate, and zinc chloride. The antibacterial activity of titanium-doped ZnO powders synthesized from zinc chloride is optimal, and its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) are lower than 0.25 g L⁻¹. Likewise, when the bacteria are treated by ZnO powders synthesized from zinc chloride, the bacterial cells are damaged most seriously, and the electrical conductance increment of bacterial suspension is slightly high. It can be inferred that the antibacterial properties of the titanium-doped ZnO powders are relevant to the microstructure, particle size, and the crystal. The powders can damage the cell walls; thus, the electrolyte is leaked from cells.     

ZnO Nanorods via Spray Deposition of Solutions Containing Zinc Chloride and Thiocarbamide

In this work we present the results on formation of ZnO nanorods prepared by spray of aqueous solutions containing ZnCl₂ and thiocarbamide (tu) at different molar ratios. It has been observed that addition of thiocarbamide into the spray solution has great impact on the size, shape and phase composition of the ZnO crystals. Obtained layers were characterized by scanning electron microscopy (SEM) equipped with energy selected backscattered electron detection system (ESB), X-ray diffraction (XRD) and photoluminescence spectroscopy (PL). Small addition of thiocarbamide into ZnCl₂ solution (ZnCl₂:tu = 1:0.25) supports development of significantly thinner ZnO nanorods with higher aspect ratio compared to those obtained from ZnCl₂ solution. Diameter of ZnO rods decreases from 270 to 100 nm and aspect ratio increases from ∼2.5 to 12 spraying ZnCl₂ and ZnCl₂:tu solutions, respectively. According to XRD, well crystallized (002) orientated pure wurtzite ZnO crystals have been formed. However, tiny ‘spot’—like formations of ZnS were detected on the side planes of hexagonal rods prepared from the thiocarbamide containing solutions. Being adsorbed on the side facets of the crystals ZnS inhibits width growth and promotes longitudinal c-axis growth.     

ZnO纳米墙薄膜的低温水热制备及其性能研究

利用控制水解浸涂法在氧化铟锡(ITO)导电玻璃上制备籽晶层,进而通过低温水热法和热处理获得了独特的氧化锌(ZnO)纳米墙薄膜结构。通过X射线衍射谱(XRD)、扫描电镜(SEM)、光电子能谱(EDS)、红外光谱(FTIR)、紫外-可见光谱(UV-Vis)和光致发光谱(PL)等对薄膜的形貌、组成和结构进行了分析表征。研究表明,ZnO纳米墙由20～100 nm厚的片层交织而成,在热处理前薄膜的组成为混合的ZnO、醋酸锌(ZnAc)和羟基醋酸锌(Zn-LHS),经500°C热处理脱除CO2、H2O等小分子后基本完全转变为ZnO,而原有层状交织纳米墙结构保留下来。室温PL谱显示薄膜在383 nm处有较强烈的紫外激发峰。结合晶体生长理论探讨了ZnO纳米墙薄膜的生长机制。     

Effect of preparation parameters on the morphologically induced photocatalytic activities of hierarchical zinc oxide nanostructures

Hierarchical zinc oxide nanostructures were successfully synthesized by facile hydrothermal and sonochemical routes using citrate and PEG as structure directing agents. The effect of precursor concentration and preparation methods on the formation of typical morphology was systematically studied under hydrothermal and sonochemical conditions. Different concentrations of zinc acetate, sodium citrate and NaOH under hydrothermal and sonochemical methods generate different hierarchical structures such as flower-like, cabbage-like, and ellipsoidal ball-like morphologies, depending on the preparation conditions. The as-prepared ZnO samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission election microscopy (TEM), photoluminescence (PL) spectroscopy, Fourier transform infrared spectroscopy (FTIR) and particle size distribution (PSD) analysis. Catalytic activities of the as-prepared samples were studied by photodegradation of Methylene blue.     

Converting Layered Zinc Acetate Nanobelts to One-dimensional Structured ZnO Nanoparticle Aggregates and their Photocatalytic Activity

We were successful in synthesizing periodic layered zinc acetate nanobelts through a hydrothermal solution process. One-dimensional structured ZnO nanoparticle aggregate was obtained by simple thermal annealing of the above-mentioned layered ZnO acetate nanobelts at 300 °C. The morphology, microstructure, and composition of the synthesized ZnO and its precursors were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and infrared spectroscopy, respectively. Low angle X-ray diffraction spectra reveal that as-synthesized zinc acetate has a layered structure with two interlayer d-spacings (one is 1.32 nm and the other is 1.91 nm). SEM and TEM indicate that nanobelt precursors were 100–200 nm in width and possesses length up to 30 μm. Calcination of precursor in air results in the formation of one-dimensional structured ZnO nanoparticle aggregates. In addition, the as-prepared ZnO nanoparticle aggregates exhibit high photocatalytic activity for the photocatalytic degradation of methyl orange (MO).     

Preparation of Zinc Oxide Nanofibers by Electrospinning

Ultra-thin fibers of zinc oxide (ZnO) were prepared by sol–gel processing and the electrospinning technique using poly(vinyl acetate) and zinc acetate as precursors. The fibers were characterized by thermogravimetric analysis, scanning electron microscopy, Fourier-transfer infrared, and X-ray diffraction, respectively. The results showed that the diameter of the precursor fibers increased with increasing zinc acetate content, and the size of the inorganic ZnO nanofibers decreased obviously as the calcining time increased.     

L-胱氨酸辅助合成硫化铋纳米棒

以Bi(NO3)3·5H2O和L-胱氨酸为反应原料,分别以N,N-二甲基甲酰胺(N,N-dimethylformamide,DMF)、蒸馏水-乙二醇(体积比为2:1)和蒸馏水为溶剂,采用溶剂热法在160℃下反应120h,得到了不同形貌的硫化铋(Bi2S3)粉体。利用X射线衍射、能量色散谱、X射线光电能谱、场发射扫描电子显微镜和透射电子显微镜分别对所合成的Bi2S3的晶型结构、组成和表面形貌等进行了表征。结果表明:所合成的产物为典型的Bi2S3正交结构,在DMF溶剂中得到的Bi2S3纳米棒长为4～11μm,直径为120nm。在蒸馏水-乙二醇和蒸馏水溶剂中得到的是片状的Bi2S3晶粒。讨论了不同溶剂对Bi2S3的形成及其形貌的影响,并根据实验结果对所合成的一维纳米棒可能的形成机理进行了探讨。     

表面活性剂对氧化锌纳米棒形貌的影响与机理

分别以PEG400和PVA124为表面活性剂辅助水热法合成了氧化锌(ZnO)纳米棒.X射线衍射分析显示:产物为结晶良好的六角结构ZnO晶体,PEG400为表面活性剂制得的ZnO比PVA124为表面活性剂时的结晶性好.用透射电镜和选区电子衍射研究了不同表面活性剂对ZnO纳米棒形貌和结晶性的影响,解释了PEG400和PVA124对ZnO形貌影响的机理,并对ZnO的生长机制进行了初步探讨.     

Green material: ecological importance of imperative and sensitive chemi-sensor based on Ag/Ag2O3/ZnO composite nanorods

In this report, we illustrate a simple, easy, and low-temperature growth of Ag/Ag₂O₃/ZnO composite nanorods with high purity and crystallinity. The composite nanorods were structurally characterized by field emission scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy which confirmed that synthesized product have rod-like morphology having an average cross section of approximately 300 nm. Nanorods are made of silver, silver oxide, and zinc oxide and are optically active having absorption band at 375 nm. The composite nanorods exhibited high sensitivity (1.5823 μA.cm⁻².mM⁻¹) and lower limit of detection (0.5 μM) when applied for the recognition of phenyl hydrazine utilizing I-V technique. Thus, Ag/Ag₂O₃/ZnO composite nanorods can be utilized as a redox mediator for the development of highly proficient phenyl hydrazine sensor.     

ZnO溶胶的制备及其抑菌性和光催化性能研究

以二水合醋酸锌和KOH为原料,聚乙烯吡咯烷酮(PVP)为表面修饰剂,制备了稳定透明的ZnO溶胶。利用X射线衍射仪、扫描电子显微镜、紫外可见分光光度计、荧光光谱仪和高效液相色谱仪对其进行了表征和测试。考察了二水合醋酸锌、KOH和PVP的用量对ZnO粒径及溶胶稳定性的影响;以金黄色葡萄球菌、大肠杆菌、绿脓杆菌、洋葱假单胞菌、白色念珠菌和黑曲霉为测试对象,采用琼脂稀释法测定ZnO溶胶的最小抑菌浓度(MIC);并对亚甲基蓝、乐果和乙酰甲胺磷溶液进行光催化性能研究。实验结果表明:在添加10 mmol二水合醋酸锌、15 mmol KOH和1.6 g PVP的较佳条件下合成的ZnO溶胶最为稳定,ZnO粒径分布均匀;ZnO溶胶有效地抑制了菌种的生长,其对金黄色葡萄球菌和洋葱假单胞菌的抑菌效果最好;同时高效地降解了亚甲基蓝、乐果和乙酰甲胺磷溶液,表现出较好的光催化活性。     

Nanoflakes to nanorods and nanospheres transition of selenious acid doped polyaniline

Morphology transition of selenious acid doped polyaniline from nanoflakes to nanorods and nanospheres was explored by changing the selenious acid-aniline (dopant-monomer) mole ratio in the aniline polymerization. The transition of polyaniline nanospheres to nanorods occurred when the dopant-monomer mole ratio was between 1 and 0.5. The formation of polyaniline nanorods was dominant when the dopant-monomer mole ratio is 0.5. At mole ratio 0.5, nanorods were obtained with the diameter at around 150 nm. At mole ratio 1, both the nanorods and nanospheres were formed and formation of the nanosphere is favored when the mole ratio is more than 1. When the mole ratio was low (0.125-0.03), polyaniline showed flakes like morphology. The morphology transition was studied by scanning electron microscopy and the molecular structure was confirmed by X-ray diffraction, FTIR and UV-vis spectroscopy. A simple and practical route to synthesize polyaniline nanostructures was demonstrated using selenious acid as effective dopant. The mechanism governing the formation of the polyaniline nanostructures is discussed.     

Controlled synthesis of carbon nanostructures using aligned ZnO nanorods as templates

By combining in situ X-ray photoemission spectroscopy, ex situ high resolution transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy, we show that chemical vapor deposition (CVD) on vertically aligned ZnO nanorods can synthesize different carbon nanostructures (CNs), whose morphology is driven by the ZnO nanorods and whose dimensions and structures change as a function of the process temperature. The CNs range from amorphous carbon cups, completely covering the nanorods, to high density one-dimensional carbon nano-dendrites (CNDs), which start to appear like short hairs on the ZnO nanorods. The nanorods are partially etched when the process is done at 630–800 °C, while they are completely etched at temperatures higher than 800 °C. In the latter case, CNDs emerge from a porous carbon sponge formed at the substrate interface but they are preferentially aligned along the location of the pristine ZnO nanorods. When used as a chemiresisitor the CND–ZnO structures have a higher sensitivity to ammonia compared to chemiresistors made by bare ZnO nanorods, to other one-dimensional CNs, like carbon nanotubes or other metal/metal-oxides hybrid CNs.     

Ultra-rapid microwave-assisted synthesis of gallium doped zinc oxide for enhanced photocurrent generation

Ultra-rapid microwave-assisted hydrothermal synthesis was performed, zinc oxide nanoparticles were fabricated and doped with gallium. Different times (5, 15, and 30 min) and concentrations of doped Ga (1, 3, and 6%) were used to improve their characteristic properties. In addition, the relation between time/dopant was analyzed. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and UV–Vis diffuse reflectance spectroscopy. Photoluminescence (PL) to verify number of defects. SEM analysis showed the formation of nanorods morphology even with a short synthesis time. The X-ray diffractograms and Raman spectra suggest the successful insertion of Ga into the ZnO lattice. The crystallite size obtained by doping was between 36 and 50 nm. The lattice parameters determined by the Rietveld refinement confirmed the formation of a wurtzite hexagonal structure. The band gap range found was 3.12–3.22 eV, which increases the potential of ZnO for optical applications. The presence of defects as result of doping was confirmed by PL. The microstructural changes of the material are enhanced by doping, which causes the photocurrent to increase from 0,002 to 0.012 mA/cm² in doped ZnO. The synthesis time and Ga doping facilitated the production of ZnO nanoparticles with improved properties.     

A facile and green strategy for large-scale synthesis of silica nanotubes using ZnO nanorods as templates

Hollow silica nanostructures exhibit important applications in catalysis, sensing, and gene delivery due to their increased surface areas, good biocompatibility, and unique optical features. Here we report a simple and green approach to synthesize silica nanotubes using environment—friendly ZnO nanorods as templates. The ZnO nanorods are first coated with a layer of uniform silica shell by a sol–gel method. Then silica nanotubes are derived from the ZnO@SiO₂ nanohybrids after removal of the ZnO nanorod cores in diluted hydrochloric acid solution. The samples at different stages were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Energy-dispersive X-ray spectroscopy, and Transmission electron microscopy. By controlling the structure of the ZnO@SiO₂ nanohybrids, such as shell thickness, and the diameter and length of ZnO nanorods, size controllable SiO₂ nanotubes can be expected.