在SDS-PVP团簇软模板中自组装多脚状金纳米粒子

利用十二烷基硫酸钠(SDS)与聚乙烯吡咯烷酮(PVP)组成的团簇为软模板, 在微波辅助下以柠檬酸钠为还原剂快速还原氯金酸生成金晶并自组装成多脚状金纳米粒子. TEM结果显示, 得到回转直径约为50 nm的多脚状纳米结构, 电子衍射(ED)证实其为多晶结构. XRD结果表明, 该多脚状金纳米结构主要沿(111)晶面生长, 构成该纳米结构的晶粒尺寸约为12.7 nm. SDS与PVP组成的团簇结构对金纳米粒子的形貌有显著影响, 固定PVP浓度时, 随着SDS浓度增大, 金纳米粒子的形貌由球形向多脚状转变, 同时还原产物水溶液的UV-Vis光谱在800 nm附近的吸收逐渐增强.     

新形金纳米片的简单制备与生长机制

在室温(~30 ℃)条件下,氯金酸(HAuCl₄)均匀混合在粘稠的表面活性剂聚乙烯吡咯烷酮(PVP)胶体(水为溶剂)中,HAuCl₄可以被PVP还原,从而形成纳米片. 本工作中,通过调整晶体生长条件,成功合成了大量新形貌的单晶金纳米片(厚度数十纳米,尺寸为数个微米). 例如,在晶体生长初期阶段,通过引入温度变化(如降温10-20 ℃),形成的金纳米片主要是六角星形,并伴有盾状、内凹外凸的三角状、截角的、三叉的及多台阶等新形纳米片. 结合理论计算,阐明了金纳米片的生长机制：在一定条件下,金(111)晶面不仅可以沿着<110>方向生长成为常规的三角或六角纳米片,还可以沿<211>、<321>等不同方向生长成含有更高指数侧面的新形金纳米片.     

花状β-氢氧化镍的合成和表征

本文介绍了以大环多胺(六甲基-1，4，8，11-四氮环14-4，11-二烯)的镍(Ⅱ)配合物溶液为反应物，水热水解制备出花状β- Ni(OH)₂亚微米结构，该花状β-Ni(OH)₂由几十个相互连接的纳米片构成。对中间产物的研究结果表明，随着配合物浓度的增加、反应时间的延长，产物形貌从卷曲的片状转变成纳米片组成的花状且花状结构逐渐增密。采用粉末X-射线衍射(XRD)、透射电子显微镜(TEM)和场发射扫描电子显微镜(FESEM)表征了产物，并采用Rietveld精修方法拟合了晶体结构。     

不同形貌Fe3O4纳米粒子的氧化沉淀法制备与表征

用一种方法成功合成出了球体、四方体、八面体、不规则多面体、三角形和不规则颗粒等六种具有不同形貌的Fe₃O₄纳米粒子，通过扫描电子显微镜(SEM)表征了粒子形貌。试样经过X-射线衍射(XRD)表征具有尖晶石结构，且结晶良好。经震动样品磁强计(VSM)测定，各种形貌的Fe₃O₄纳米粒子都具有良好的磁性，其中八面体形貌的Fe₃O₄纳米粒子的饱和磁化强度达到86.56 emu·g^-1，剩磁为10.64 emu·g^-1，矫顽力为138 Oe。讨论了不同形貌的Fe₃O₄纳米粒子的形成机制，得出了晶核的生长环境对纳米粒子的形貌有重要影响的结论。     

氧化亚铜微/纳米结构的形貌可控制备及光催化和防污性能

利用简便易行的液相法,采用葡萄糖为还原剂,通过调整加料方式、反应温度、NaOH用量等条件,实现具有{110}截面八面体、八面体和短足形等形貌的Cu₂O微/纳米结构的可控制备,运用透射电子显微镜、扫描电子显微镜、紫外可见分光光度计等对产物进行组成、结构、形貌和光响应的表征,对Cu₂O的形貌结构和生长机理进行研究。对比和优化了具有不同形貌的Cu₂O微/纳米结构对甲基橙染料的光催化性能。将不同形貌的微/纳米Cu₂O作为防污剂复配的自抛光防污涂料,涂层磨蚀率、接触角与实海挂板实验证明该涂料具有良好的防污性能。     

纳米金的制备及其在重金属离子检测中的应用——一个分析化学综合性研究型实验

具有可控粒径、形貌纳米金的制备是近年来的一大研究热点。本实验以铯盐硼簇(Cs₂B₁₂H₁₂)为还原剂和包覆剂,成功在水相中将氯金酸还原制备了纳米级别的单分散纳米金颗粒。并将制备得到的纳米金胶体应用于重金属离子(Cr₃₊和Pb₂₊)的比色法检测中,进一步利用紫外可见光谱可以对重金属离子实现定量检测。通过该实验,可以让学生学习制备纳米金的方法,掌握利用紫外等多种分析手段对纳米粒子结构及性能进行表征的技能。     

室温下制备Cu7S4和Ag2S的球形空心纳米粒子

以Cu₂O和Ag₂O纳米粒子为前驱体,利用Kirkendall效应,在室温条件下制备出Cu₇S₄和Ag₂S的球形空心纳米粒子。用X-射线衍射(XRD)、透射电镜(TEM)、扫描电镜(SEM)等测试手段对产物进行了表征。结果表明,粒子的空心化程度取决于反应物的物质的量之比;空心粒子的形貌与前驱体粒子的形貌很相似。研究了这种反应的机理,并对这两种氧化物发生这类反应的难易程度作了理论探讨。     

TiO2纳米纤维无纺布的制备及光催化性能研究

以聚乙烯吡咯烷酮(PVP)作为配位剂与钛酸正丁酯(Ti(C₄H₉O)₄)反应制得前驱体，再以乙醇为溶剂，CH3COOH作为催化剂，采用静电纺丝法制得PVP/TiO₂复合纳米纤维，经550 ℃、700 ℃和900 ℃焙烧后分别得到以锐钛矿型的TiO₂为主、以金红石型TiO₂为主和完全金红石晶型的TiO₂纳米纤维。对所制得的纳米纤维的结晶度、纯度和形貌，分别采用差热-热重分析(TG-DTA)、红外光谱(IR)、X射线粉末衍射(XRD)、扫描电镜(SEM)等进行了表征。光降解苯酚水溶液的实验结果表明，550 ℃下煅烧得到的以锐钛矿占主体的TiO₂纳米纤维，2 h使浓度为50 mg·L^-1苯酚水溶液的降解率超过85%，这充分说明这种TiO₂电纺纳米纤维具有良好的光催化性能。     

花状TiO2分级结构的可控合成与其光催化性能

采用水热法可控合成了花状TiO₂分级结构材料,运用扫描电镜、透射电镜、X射线衍射、N₂物理吸附-脱附等手段,对其进行了表征,系统研究了NaOH用量、H₂O₂浓度、HNO₃浓度、反应温度及时间等因素对所得样品形貌的影响,并评价了它们的光催化性能.结果表明,花状TiO₂分级结构为锐钛矿相,颗粒大小均一;随制备条件的变化,构成花状TiO₂分级结构的基元结构分别为纳米线、纳米片,纳米线直径约25nm,纳米片厚度不足10nm;该样品具有较高的比表面积,表现出良好的单次光催化活性与重复使用性能.     

W/O型微乳液中不同形貌PbS纳米粒子的制备及其形成机理的探讨

用聚乙二醇辛基苯基醚(OP)/异辛醇/环己烷/水溶液所形成的微乳液体系控制合成出了PbS纳米粒子，考察了微乳液中水与表面活性剂的物质的量的比(ω₀)、反应物浓度及浓度比、陈化时间等条件对产物形貌的影响。采用透射电子显微镜(TEM)、X-射线衍射(XRD)分别对产物的结构、粒度和形貌进行了表征。结果表明，在微乳液体系中，控制不同的实验条件，可以成功地合成球形、梭形、针状和棒状的PbS纳米粒子，并且粒径分布集中，无团聚现象。论文还对不同形貌PbS纳米粒子的形成机理进行了探讨。     

Synthesis and Magnetic Properties of Co3O4 Nanoflowers

Co3O4 nanoflowers were prepared through a sequential process of a hydrothermal reaction and heat treatment. The as-synthesized products were characterized by powder X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and infrared spectrum. These nanoflowers consist of numerous Co3O4 nanofibers, which have diameters of 20-40 nm, and lengths ranging from 100 nm to 500 nm. They have pore structures and Brunauer-Emmett-Teller surface area of ?34.61 m2/g. The temperature dependence curves of magnetization in zero-field-cooled conditions and field-cooled indicate mainly antiferromagnetism and weak ferromagnetism of Co3O4 nanoflowers at blocking temperature of ?34 K respectively.     

烟草花叶病毒介导合成三角形金纳米片

利用碱处理烟草花叶病毒的生物还原性和辅助结构导向作用,在室温下以水为溶剂直接还原氯金酸制备出三角形金纳米片。采取透射电子显微镜（TEM）、高分辨透射电子显微镜（HRTEM）、选区电子衍射（SAED）和紫外-可见光谱仪（UV-Vis）等对所制备金纳米片的结构和性能进行了表征。结果显示,所制备三角形金纳米片为单晶,三角面为{111}晶面簇,边长在40 ~120 nm之间,厚度约为15 nm。该材料在可见光区有两个等离子共振吸收峰,在感光成像、生物检测和催化等领域具有很好的应用前景。     

Enhanced electrochemical evolution of oxygen by using nanoflowers made from a gold and iridium oxide composite

We report on the synthesis of a composite made from iridium oxide and gold that has a flower-like morphology. The ratio of iridium oxide to gold can be controlled by altering the concentrations of the metal precursors or the pH of the solution containing the reductant citrate. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and laser confocal micro-Raman spectroscopy were applied to characterize the structures of the nanoflowers, and a mechanism of their formation was deduced. The nanoflowers display an electrocatalytic activity in an oxygen evolution reaction (OER) that is significantly enhanced compared to bare iridium oxide nanoparticles. The highest turnover frequency for the OER of the new nanoflowers is 10.9?s^?1, which is almost one order of magnitude better than that of the respective nanoparticles. These attractive features are attributed to the high oxidation states of iridium in the nanoflowers which is caused by the transfer of electronic charge from metal oxides to gold, and also to the flower fractal structure which is thought to provide a much more accessible surface than suspensions of the respective nanoparticle.

Solvent‐free Synthesis of Hexagonal Iron Sulfide Nanoflowers

Employing green and economic solvent‐free synthesis route, hexagonal iron sulfide (Fe₇S₈) nanoflowers were successfully synthesized for the first time. In the experiment, ferric hexadecylxanthate was used as the precursor, and hexagonal iron sulfide (Fe₇S₈) nanoflowers were obtained by thermal decomposition of the precursor at 260°C without any additional solvent or inert gas protection. The as‐prepared iron sulfide nanoflowers were characterized by means of X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The characterization results indicated that the nanoflowers had uniform size distribution with an average size of about 160 nm. The proposed strategy provides a possible general route for the synthesis of other metal chalcogenide nanostructures.     

Controlled synthesis of monodispersed AgGaS2 3D nanoflowers and the shape evolution from nanoflowers to colloids

Monodispersed AgGaS₂ three-dimensional (3D) nanoflowers have been successfully synthesized in a “soft-chemical” system with the mixture of 1-octyl alcohol and cyclohexane as reaction medium and oleylamine as surfactant. The crystal phase, morphology and chemical composition of the as-prepared products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution TEM (HTEM), respectively. Results reveal that the as-synthesized AgGaS₂ nanoflowers are in tetragonal structure with 3D flower-like shape. Controlled experiments demonstrated that the shape transformation of AgGaS₂ nanocrystals from 3D nanoflowers (50 nm) to nanoparticles (10-20 nm) could be readily realized by tuning the reaction parameters, e.g., the ratio of octanol to cyclohexane, the length of carbon chain of fatty alcohol, the concentration of oleylamine, etc. The UV-vis and PL spectra of the obtained AgGaS₂ nanoflowers and colloids were researched. In addition, the photoelectron energy conversion (SPV) of AgGaS₂ nanoflowers was further researched by the surface photovoltage spectra.     

Synthesis and characterization of CuInS<Subscript>2</Subscript> nanoflowers

Uniform crystalline CuInS₂ nanoflowers with an average size of 25 nm were synthesized by a hot-injection strategy using CuAc, In(Ac)₃ and sulfur powder as precursors and oleylamine as both the solvent and ligand. Various methods including X-ray diffraction, transmission electron microscopy and absorption spectroscopy were used to characterize CuInS₂ nanoflowers. Control experiments indicated that CuInS₂ nanoflowers were formed through 3D attachment of forming primary nanodots. The obtained CuInS₂ nanoflowers are promising for low-cost, high efficiency solar cells due to several advantages such as the simplicity of synthesis, size and morphology uniformity, stability of dispersion and large surface area for charge separation.     

Murraya Koenigii leaf-assisted rapid green synthesis of silver and gold nanoparticles

A facile bottom-up 'green' and rapid synthetic route using Murraya Koenigii leaf extract as reducing and stabilizing agent produced silver nanoparticles at ambient conditions and gold nanoparticles at 373 K. The nanoparticles were characterized using UV-vis, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. This method allows the synthesis of well-dispersed silver and gold nanoparticles having size ～10 nm and ～20 nm, respectively. Silver nanoparticles with size ～10 nm having symmetric SPR band centered at 411 nm is obtained within 5 min of addition of the extract to the solution of AgNO3 at room temperature. Nearly spherical gold nanoparticles having size ～20 nm with SPR at 532 nm is obtained on adding the leaf extract to the boiling solution of HAuCl4. Crystallinity of the nanoparticles is confirmed from the high-resolution TEM images, selected area electron diffraction (SAED) and XRD patterns. From the FTIR spectra it is found that the biomolecules responsible for capping are different in gold and silver nanoparticles. A comparison of the present work with the author's earlier reports on biosynthesis is also included.     

Green synthesis of zinc oxide nanoflowers using Hypericum triquetrifolium extract: characterization,antibacterial activity and cytotoxicity against lung cancer A549 cells

Zinc oxide nanoparticles have attracted significant interest in recent years due to their unique multifunctional chemical and physical properties along with their biological activities. This study demonstrated for the first time the biogenetic synthesis of zinc oxide nanoparticles by utilization of the methanolic extract of Hypericum triquetrifolium (HT). The obtained nanoparticles (HT-ZnO) were characterized by ultraviolet–visible spectroscopy (UV–Vis), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The shape of the resulted nanoparticles is fusiform nanoflowers with an average hydrodynamic size of 275.46 ± 0.20 nm and a zeta potential of −8.23 ± 0.26 mV. SEM micrographs revealed that HT-ZnO nanoflowers have a multi-process structure in which one of the processes is large and the others have similar smaller dimensions. The synthesized nanoflowers have an average length of 312.28 ± 78.93 nm and the tip of its processes has a width of 48.69 ± 9.71 nm. The antimicrobial activity of HT-ZnO nanoflowers was performed using microbroth dilution format. It showed a bactericidal mode of action against Gram-positive Staphylococcus aureus and Enterococcus faecalis with MIC/MBC values of 20 μg/mL and 5 μg/mL, respectively. MTT assay had revealed that HT-ZnO nanoflowers caused a dose-dependent decline in the viability of A549 adenocarcinomic human alveolar basal epithelial cells with an IC₅₀ value of 20.45 μg/mL. The effect of HT-ZnO nanoflowers on the migration and colony formation abilities against the same cells was evaluated as well. In conclusion, zinc oxide nanoflowers were successfully synthesized using methanolic extract of H. triquetrifolium. The resulting particles showed a bactericidal effect against Gram-positiveS. aureus and E. faecalis and a cytotoxic activity against A549 cells.     

Synthesis of single-crystal gold nanosheets of large size in ionic liquids

Large-size single-crystal gold nanosheets have been successfully prepared by microwave heating of HAuCl(4) in ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, without any additional template agent. Transmission electron microscopy (TEM), electron diffraction (ED), scanning electron microscopy (SEM), and X-ray powder diffraction (XRD) were used to characterize the resultant gold nanosheets. It was demonstrated that the ionic liquid could act as template agent for the formation of gold nanosheets. The present synthesis route is very simple and fast. It can be expected that the method can be extended to the fabrication of other metal nanosheets in ionic liquids.     

Green synthesis of catalytic Zinc Oxide nano-flowers and their bacterial infection therapy

Herein, Zinc Oxide nanoflowers (ZnONFs) with low cost, non-hazardous and renewable phytochemicals from plant (Thlaspi arvense) extract were synthesized via facile method under controlled optimized experimental conditions. The as-fabricated Zinc Oxide nanoflowers were comprehensively characterized by UV–visible spectroscopy, Fourier Transform infrared spectroscopy, X-ray diffraction, Scanning electron microscopy, High-resolution transmission electron microscopy, and Energy dispersive spectroscopy techniques. The bio-fabricated Zinc Oxide nanoflowers performed an admirable potential activity against Gram-negative bacterium (Escherichia coli) and significantly inhibited its growth, due to an intracellular generation of reactive-oxygen-species. The photocatalytic performances of as bio-synthesized Zinc Oxide nanoflowers were also tested by reducing 4-nitrophenol and methylene blue. The superior photocatalytic activities of Zinc Oxide nanoflowers are attributed to the high surface area, efficient photogenerated electron and hole separation owing to the capped plant moieties. The as-synthesized Zinc Oxide nanoflowers by green method exhibited a significant antibacterial activity and efficient photocatalytic performances. This synthetic strategy will open a new window for the fabrication of nanomaterial with effective removal of wastewater contaminants and pathogens.