纳米银导电墨水及其成膜性能研究

用化学还原法制备了纳米Ag粉,并通过X射线衍射(XRD)、激光粒度分析仪(LPSA)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)等测试手段对样品进行性能表征。在所选择的实验条件下制备了类球形分布、分散性好的Ag纳米颗粒,其粒径主要分布在5～50nm范围,平均粒径为16nm,晶体结构为fcc结构。经涂布检测,Ag纳米墨水制备的墨膜均匀致密,150℃回火后,银粒子烧结明显,有微孔均匀分布。     

银/壳聚糖复合物的制备与表征

采用液相化学还原法合成了银/壳聚糖(Ag/CS)复合物,探索并确定了合成复合物的最佳工艺条件.对复合物的结构和性能进行了表征,结果显示,CS分子通过静电效应和位阻效应阻止了Ag纳米粒子的聚集,使其均匀分散于复合物中;复合物中Ag纳米粒子为面心立方结构,平均粒径小于10nm;与Ag纳米粒子复合后CS的热稳定性明显高于纯CS.     

Ag/TiO2纳米管阵列等离子体光催化剂的制备及性能研究

以阳极氧化法制备的二氧化钛(TiO_2)纳米管阵列为基底,利用化学还原法制备了不同银(Ag)含量的Ag/TiO_2复合薄膜,并对其进行表征。结果表明,化学还原法有利于Ag纳米颗粒在TiO_2纳米管上的均匀分布,Ag能产生表面等离子体共振吸收,有效增强TiO_2纳米管阵列对可见光的吸收能力,Ag的修饰大幅度提高了TiO_2纳米管阵列对气相苯的光催化降解活性,在光催化反应80min条件下,Ag含量为2%(wt,质量分数)制得的Ag/TiO_2复合薄膜光催化活性最佳,对气相苯的降解率达到97%。     

一种铁纳米材料的制备方法

在常温常压、无任何催化剂的条件下,用电子束辐照法制备纳米铁的前驱体纳米氧化铁,然后用高纯氢还原纳米氧化铁可制得纳米铁.采用X射线衍射仪(XRD)分析试验产物的结构、大小,并用激光衍射粒度分布仪(LSPSDA)观测其粒度分布,可以验证实验效果.介绍了用电子束辐照技术结合高纯氢还原的方法制备铁纳米材料,并探讨了水溶液铁离子的辐射化学反应机理,以及影响纳米氧化铁还原的主要因素.     

负载纳米银颗粒的纳米纤维膜的制备与表征

采用一步还原法和螯合法制备Ag/PAN纳米纤维膜。采用SEM,UV,XRD,FT-IR傅里叶变换红外光谱仪对该纤维形貌,银粒子晶型、尺寸、官能团进行表征。得知两种方法都可制备出嵌有(或附着)纳米银颗粒的PAN纳米纤维膜,银粒子的粒径可以达10nm,且经过比较,Ag/PAN膜经过还原处理后,表面Ag粒子的含量更高,分布更均匀。     

温度对ZnO／Ag纳米复合抗菌剂前驱体及产物的影响规律研究

以硫酸锌、硝酸银为原料，碳酸氢氨为沉淀剂制备出高纯度ZnO／Ag纳米复合抗菌剂。重点研究了合成温度及煅烧温度对前驱体微观形貌及最终产物的结构、成份、形貌的影响规律。用TEM、XRD、TG-DTG对前驱体和ZnO／Ag纳米复合抗菌剂进行了表征，结果表明：随着合成温度的升高，前驱体产物的形态由线棒状逐渐变为球团状，并且由非晶态逐渐转化为晶态；450℃煅烧所得复合粉体由六方纤锌矿纳米ZnO和立方结构纳米Ag组成，粒径集中在15nm左右，粒子大小均匀，分散性良好；经权威机构检测本抗菌剂抗菌性能优异。     

SDS表面修饰纳米ZnO制备及抗菌性能研究

以SDS(十二烷基硫酸钠)为表面活性剂,乙酸锌为前驱体,水-乙醇混合溶剂为反应介质,通过溶液化学方法制得Zn O纳米粒子。实验过程中考察了反应温度、表面活性剂与前驱体物质的量比等因素对Zn O纳米粒子制备过程的影响。通过紫外-可见吸收光谱(UV-Vis)、透射电子显微镜(TEM)、X-射线衍射(XRD)等对Zn O纳米粒子的结构和性质进行了表征。结果表明,控制合适的反应条件,可以得到量子尺寸效应较为明显的Zn O纳米粒子,Zn O纳米粒子具有球状形貌,尺寸在5～10 nm之间,且具有典型的纤锌矿晶体结构。抗菌实验结果表明,所合成的Zn O纳米粒子具有较好的抗菌性能。     

自组装Ag纳米颗粒的表面等离子体共振及其对CdSe量子点的荧光增强效应

采用柠檬酸三钠还原硝酸银的方法制备了Ag纳米粒子溶胶,利用静电自组装技术制得单分散Ag纳米颗粒薄膜.研究了该Ag纳米颗粒薄膜的光学特性,通过改变反应物浓度和后期的热退火温度,有效调控了Ag纳米颗粒尺度和其在外场作用下产生的表面等离子体共振(SPR)特性.将所制备的Ag纳米颗粒薄膜与CdSe量子点耦合,利用SPR对荧光的...     

湿化学法合成纳米AlN粉末

采用醇盐水解工艺结合碳热氮化还原法进行纳米Al N粉末的制备。以异丙醇铝、果糖、无水乙醇为原料,制备出透明的凝胶,干燥后得到分子水平混合的前驱体,在1 450℃经碳热氮化还原法制备出单相Al N纳米粉末。系统研究了前躯体形成机制,以及碳热氮化还原的温度和时间、C/Al摩尔比、凝胶温度等因素对合成粉体的影响。采用XRD、TG-DSC和SEM对合成产物的特性进行了分析和表征。通过优化工艺,制得类球形的Al N粉末颗粒,其颗粒大小为30~90 nm。     

苯甲酸对化学沉淀法制备氧化锌纳米粉体的影响

利用化学沉淀法,对前驱体沉淀物在采用苯甲酸水热改性和未改性2种条件下分别制备氧化锌粉体,通过X射线衍射、扫描电镜等表征手段考察苯甲酸水热改性对氧化锌颗粒形貌的影响,并对苯甲酸水热改性片状氧化锌纳米颗粒的形成机理进行探讨。结果表明:在未改性条件下制得的氧化锌为颗粒状,平均粒径为300~400 nm;采用苯甲酸对前躯体沉淀物进行水热改性可得片状氧化锌纳米颗粒,片层厚度为30~60 nm。     

Silver sulfide nanoparticle assembly obtained by reacting an assembled silver nanoparticle template with hydrogen sulfide gas

A fast, simple procedure is described for obtaining an assembly of silver sulfide nanoparticles (Ag(2)S NPs) on a glass substrate through reaction of a template of an assembled layer of silver nanoparticles (Ag NPs) with hydrogen sulfide (H(2)S) gas. The Ag NP template was prepared by assembling a monolayer of spherical Ag NPs (mean diameter of 7.4?nm) on a polyethylenimine-treated glass substrate. Exposure to pure H(2)S for 10?min converted the Ag NPs of the template to Ag(2)S NPs. The resulting Ag(2)S NP assembly, which retains the template nanostructure and particle distribution, was characterized by optical absorption spectroscopy, atomic force microscopy, transmission electron microscopy (TEM), scanning high resolution TEM, energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. The Ag(2)S NPs have a crystal structure of monoclinic acanthite, and while they retained the spherical shape of the original Ag NPs, their mean particle size increased to 8.4?nm due to changes to the crystal structure when the Ag NPs are converted into Ag(2)S NPs. The measured optical absorption edge of the Ag(2)S NP assembly indicated an indirect interband transition with a band gap energy of 1.71?eV. The Ag(2)S NP assembly absorbed light with wavelengths below 725?nm, and the absorbance increased monotonically toward the UV region.     

A facile method to prepare size-tunable silver nanoparticles and its antibacterial mechanism

The antibacterial effect of silver nanoparticles (denoted as Ag NPs) is closely related to size. This could partly explain why size controllable synthesis of Ag NPs for bactericidal application is drawing much attention. Thus, we establish a facile and mild route to prepare size-tunable Ag NPs with highly uniform morphologies and narrow size distributions. The as-prepared Ag NPs with averaged sizes of 2, 12 and 32?nm were characterized by transmission electron microscopy (TEM), ultraviolet–visible absorption spectroscopy (UV–vis), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The antimicrobial effect of the as-prepared Ag NPs with different particles size was assessed by broth dilution and disk diffusion as well as measurement of optical density (OD₆₀₀). Moreover, their antibacterial mechanism was discussed in relation to morphology observation of microorganism by scanning electron microscopy (SEM) and to concentration detection of Ag⁺ by stripping voltammetry. It was found that the parameters such as reactant molar ratio, reaction time, dropping speed, and most of all, pH of the reactant solutions, have significant influences on size-regulation of Ag NPs. The as-prepared Ag NPs exhibit excellent antibacterial properties, and their antimicrobial activities increase with decreasing particles size. Besides, two kinds of mechanisms, i.e., contact action and release of Ag⁺, are responsible for the antimicrobial effect of Ag NPs.     

Rapid biologically one-step synthesis of stable bioactive silver nanoparticles using Osage orange (Maclura pomifera) leaf extract and their antimicrobial activities

Synthesis of nanoparticles by using natural products as reducing and stabilizing agents have been widely used in various fields especially medicine, primarily because of its lower cost, simplicity, and less toxic byproducts. In the present work, silver nanoparticles (Ag NPs) were rapidly synthesized from silver nitrate in a green one-step synthesis by the aqueous extracts of Osage orange (Maclura pomifera) leaf as a reducing and stabilizing agent simultaneously. The effects of pH, extract quantity, and silver salt concentration were investigated to determine the optimum conditions of green synthesis of Ag NPs. The synthesized Ag NPs were characterized by different techniques including UV–Visible (UV–Vis) absorption spectroscopy, X-ray diffraction (XRD), Fourier transform Infrared (FT-IR) Spectroscopy, and Transmission Electron Microscopy (TEM). The Ag NPs showed surface plasmon resonance centered at 415?nm. The XRD pattern and TEM analysis revealed spherical, stable, and uniform Ag NPs with the average particle size of about 12?nm. The FT-IR spectroscopy showed that mainly hydroxyl functional groups, as both the reducing and stabilizing agent are responsible for silver nanoparticles synthesis. The antimicrobial activity of the synthesized Ag NPs showed a significant microbicidal effect on all clinical isolates especially, Gram-negative bacteria and fungi. These results suggest that such stable and uniform Ag NPs can be synthesized rapidly and simply for clinical as well as pharmaceutical applications.     

Structural,electrical, and rheological properties of palladium/silver bimetallic nanoparticles prepared by conventional and ultrasonic-assisted reduction methods

Polyvinylpyrrolidone stabilized Pd/Ag bimetallic nanoparticles (NPs) with average particle sizes of 9 and 6 nm were synthesized by simultaneous reduction in the presence and absence of ultrasound waves, respectively. The prepared NPs were characterized by six methods including X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution-TEM (HRTEM), UV–vis spectroscopy, scanning tunneling microscopy (STM), and energy dispersive X-ray (EDX) analysis. The rheological properties of Pd/Ag NPs in ethylene glycol as a base fluid with various mass fractions of NPs from 2% to 5% at different temperatures were studied experimentally and theoretically. The experimental results showed that viscosity of Pd/Ag NPs in ethylene glycol increases with increasing particle mass fraction and decreases with increasing temperature. A maximum of 31.58% increase in viscosity of ethylene glycol at 20 °C was observed when 5% Pd/Ag NPs was added. Measurement of the electrical conductivity of nanofluids of Pd/Ag bimetallic NPs in distilled water at different mass fractions and temperatures was performed. A 3841% increase in electrical conductivity of distilled water at 25 °C was observed when 1% Pd/Ag NPs was added. Both the rheological and electrical properties of Pd/Ag bimetallic NPs were measured in ethylene glycol and distilled water, respectively for the first time.     

Photocatalytic and antibacterial properties of a TiO2/nylon-6 electrospun nanocomposite mat containing silver nanoparticles

Silver-impregnated TiO(2)/nylon-6 nanocomposite mats exhibit excellent characteristics as a filter media with good photocatalytic and antibacterial properties and durability for repeated use. Silver nanoparticles (NPs) were successfully embedded in electrospun TiO(2)/nylon-6 composite nanofibers through the photocatalytic reduction of silver nitrate solution under UV-light irradiation. TiO(2) NPs present in nylon-6 solution were able to cause the formation of a high aspect ratio spider-wave-like structure during electrospinning and facilitated the UV photoreduction of AgNO(3) to Ag. TEM images, UV-visible and XRD spectra confirmed that monodisperse Ag NPs (approximately 4 nm in size) were deposited selectively upon the TiO(2) NPs of the prepared nanocomposite mat. The antibacterial property of a TiO(2)/nylon-6 composite mat loaded with Ag NPs was tested against Escherichia coli, and the photoactive property was tested against methylene blue. All of the results showed that TiO(2)/nylon-6 nanocomposite mats loaded with Ag NPs are more effective than composite mats without Ag NPs. The prepared material has potential as an economically friendly photocatalyst and water filter media because it allows the NPs to be reused.     

Ag nanoparticles enhanced near-IR emission from Er3+ ions doped glasses

Vitreous materials containing rare-earth (RE) ions and metallic nanoparticles (NPs) attract considerable interest because the presence of the NPs may lead to an intensification of luminescence. In this work, the characteristics of 1.54 μm luminescence for the Er³⁺ ions doped bismuthate glasses containing Ag NPs were studied under 980 nm excitation. The surface plasmon resonance (SPR) band of Ag NPs appears from 500 to 1500 nm. Transmission electron microscopic (TEM) image reveals that the Ag NPs are dispersed homogeneously with the size from 2 to 7 nm. The strength parameters Ω_t(t = 2, 4, 6), spontaneous emission probability (A), radiative lifetime (τ) and stimulated emission section (σ_em) of Er³⁺ ions were calculated by the Judd–Ofelt theory. When the glass contains 0.2 wt% AgCl, the 1.54 μm fluorescence intensity of Er³⁺ reaches a maximum value, which is 7.2 times higher than that of glass without Ag NPs. The Ag NPs embedded glasses show significantly fluorescence enhancement of Er³⁺ ions by local field enhancement from SPR.     

A facile method for preparing 3D graphene/Ag aerogel via gamma-ray irradiation

In this article, we report a simple method to fabricate graphene and Ag nanoparticles (NPs) composite aerogel (GA/Ag). The GO and Ag ions were in situ reduced by gamma-ray irradiation and went through self-assembly three-dimensional (3D) honeycomb-like porous composite aerogel in the presence of isopropanol. Measurements using XRD, XPS, SEM, TEM revealed that the GO and Ag ions can efficiently reduction into rGO and Ag NPs. In addition, Ag NPs were homogeneously attached to the graphene nanosheets of the honeycomb-like porous structure and had a typical diameter of 30–70 nm. Thus the gamma-ray irradiation-induced synthesis is an efficient method for preparing 3D GA/Ag composite.     

Green synthesis and characteristic of core-shell structure silver/starch nanoparticles

An eco-friendly method was put forward to synthesize Ag nanoparticles (Ag NPs) by using biodegradable starch as a stabilizing agent. The silver ion from AgNO₃ was reduced by glucose in soluble starch solution. Morphological observation and characterization of Ag NPs were performed by using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and UV–vis absorption spectroscopy. HRTEM showed that Ag NPs were covered by starch layer to form spherical core-shell Ag/starch NPs with diameter ranging from 5 to 20 nm. XRD pattern confirmed the presence of Ag NPs with face-centered cubic (fcc) structure. All these results indicated that starch played an important role in stabilizing Ag NPs.     

Microwave-assisted rapid synthesis of anisotropic Ag nanoparticles by solid state transformation

Anisotropic silver nanoparticles (NPs) have been synthesized rapidly using microwave irradiation by the decomposition of silver oxalate in a glycol medium using polyvinyl pyrolidone (PVP) as the capping agent. The obtained Ag nanoparticles have been characterized by UV-visible spectroscopy, powder x-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) studies. Anisotropic Ag nanoparticles of average size around 30?nm have been observed in the case of microwave irradiation for 75?s whereas spherical particles of a size around 5-6?nm are formed for 60?s of irradiation. The texture coefficient and particle size calculated from XRD patterns of anisotropic nanoparticles reveal the preferential orientation of (111) facets in the Ag sample. Ethylene glycol is found to be a more suitable medium than diethylene glycol. A plausible mechanism has been proposed for the formation of anisotropic Ag nanoparticles from silver oxalate.     

Reversible dispersion and aggregation of Ag2S nanoparticles capped with azobenzene-derivatized alkanethiols

Ag2S nanoparticles (NPs) of 3.1 +/- 0.6, 8.1 +/- 1.0, and 10.2 +/- 1.6 nm in diameter capped with a long-chain amidoamine derivative (C18AA) were synthesized by a modified Brust method. Ag2S NPs capped with two types of azobenzene-derivatized alkanethiol differing in chain length (2AM10SH and 8AM5SH) were obtained by the ligand exchange method. The trans to cis photoisomerization conversion of 2AM10SH and 8AM5SH on Ag2S NPs dispersed in toluene was above 95%. 2AM10SH-capped Ag2S NPs of 8.1 nm or more in toluene were found to show reversible dispersion-aggregation behavior under alternating irradiation with UV and visible lights, i.e., Ag2S NPs capped with trans- and cis-2AM10SH were in dispersed and aggregated states, respectively. However, Ag2S NPs of 3.1 nm capped with 2AM10SH and Ag2S NPs of 8.1 nm capped with 8AM5SH were always in a dispersed state regardless of whether 2AM10SH and 8AM5SH were in the trans or cis conformation.