Facile sonochemical synthesis and photocatalysis of Ag nanoparticle/ZnWO_4-nanorod nanocomposites

A facile sonochemical method was developed to synthesize metallic Ag spherical nanoparticles on the surface of ZnWO_4 nanorods by forming heterostructure Ag/ZnWO_4 nanocomposites.The Ag/ZnWO_4 nanocomposites were characterized by X-ray powder diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS).The experimental results showed that fcc metallic Ag nanoparticles were supported on surface of monoclinic sanmartinite ZnWO_4 nanorods.The Ag3d_(3/2) and Ag 3 d_(5/2) peaks have well-separated binding energies of 6.00 eV,certifying the existence of metallic Ag.The Ag/ZnWO_4 nanocomposites were evaluated for photodegradation of methylene blue(MB)induced by ultraviolet-visible(UV-Vis)radiation.In this research,heterostructure 10 wt% Ag nanoparticle/ZnWO_4-nanorod composites have the highest photocatalytic activity of 99%degradation of MB within 60 min.The increase in photocatalytic activity was the result of photoinduced electrons in conduction band of ZnWO_4 that effectively diffused to metallic Ag spherical nanoparticles and the inhibition of electron-hole recombination process.     

Ag2S/rGO纳米复合材料的细菌还原制备及光电性能研究

以一种革兰氏阴性菌(S. oneidensis MR-1)为生物还原剂,Na2S2O3为电子受体,在氧化石墨烯(GO)表面原位合成了Ag2S/rGO纳米复合材料,对其进行了表征和光电性能测试。结果表明,细菌还原得到粒径约10 nm的Ag2S纳米粒子,均匀分布在还原氧化石墨烯(rGO)上;光电性能测试表明,与纯Ag2S相比,Ag2S/rGO纳米复合材料电极的光电流密度约提高了3倍,光生电子-空穴对的分离效率更高,表现出更加优异的光电化学性能。     

Synthesis and Characterization of Ag/Graphene Nano- composite

采用氧化还原法制备不同银含量的银/石墨烯纳米复合材料 (银质量分数分别为0%, 30%, 46%, 56%, 63%)。并通过X射线衍射(XRD)、光电子能谱仪(XPS)、高倍透射电子显微镜(HRTEM)和拉曼光谱(Raman)分析银含量对银/石墨烯纳米复合材料形态和显微结构的影响。结果表明,氧化石墨和银离子被成功地还原成银/石墨烯纳米复合材料,所得石墨烯由3~4单层碳原子层堆砌缠绕而成,同时银纳米颗粒沉积在石墨烯的表面。银纳米颗粒的介入有效地阻碍了石墨烯的团聚,增大了石墨烯的比表面积。银纳米颗粒的尺寸与银含量相关,当银含量较低时,银纳米颗粒在石墨烯表面具有很好的分散性且粒度基本分布在25~50 nm之间,而当银含量超过46%时将会导致银纳米颗粒的团聚。另外, 银纳米颗粒增强了石墨烯的拉曼效应。     

INFLUENCE OF THE ALIGNMENT OF TiO_2 NANOPARTICLES ON OPTICAL AND STRUCTURAL PROPERTIES OF POLY(PHENYLENEVINYLENE) FILMS

A series of poly(phenylenevinylene) (PPV)/titanium oxide (TiO2) nanocomposites with different contents of TiO2 nanoparticles were prepared from mixtures of PPV precursor and titanium butoxide ethanol solution in a sol-gel process. TEM images showed the formation of the connected network of TiO2 nanoparticles with a higher content of TiO2, which resulted in the titanium butoxide hydrolyzed to form Ti organic compound. Meanwhile, the conjugation of PPV polymer chains can be interrupted by the TiO2 network structure. The PL spectra revealed that the emitted light of the PPV/TiO2 nanocomposites blue shifted without fine structure and the PL intensity enhanced when the TiO2 network formed. In the lifetime spectroscopy of positron annihilation, the structural properties of the PPV dominated the character of the nanocomposites, in which the formation of the o-Ps was presented in free volume pf polymer, when the content of TiO2 was below 10%. Further increasing the content of TiO2     

Conducting polymer functionalized multi-walled carbon nanotubes with noble metal nanoparticles: Synthesis,morphological characteristics and electrical properties

We report the synthesis of conducting polyaniline-functionalized multi-walled carbon nanotubes (MWCNTs-f-PANI) containing noble metal (Au and Ag) nanoparticles composites (MWCNTs-f-PANI-Au or Ag-NC). MWCNTs-f-PANI was initially synthesized by functionalizing acyl chloride terminated carbon nanotubes (MWCNTs-COCl) with 2,5-diaminobenzenesulphonic acid (DABSA) via amide bond formation, followed by surface initiated in situ chemical oxidative graft polymerization of aniline in the presence of the ammonium persulphate (APS) as an oxidizing agent. MWCNTs-f-PANI was then dispersed into an aqueous Au or Ag metal salt solution followed by the addition of sodium citrate, which acted as a reducing agent. The resulting composite contained a high level of well dispersed Au or Ag nanoparticles (MWCNTs-f-PANI/Au-NC or MWCNTs-f-PANI-Ag-NC). Morphological and structural characteristics, as well as electrical conducting properties of the hybrid nanocomposites were characterized using various techniques including high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–visible spectroscopy (UV–vis) and four-probe measurements. FT-IR spectra confirmed that PANI was covalently bonded to MWCNTs. TEM images revealed the presence of Au or Ag nanoparticles finely dispersed in the composites with a size of <15 nm. XRD analysis revealed the presence of strong interactions between the metal nanoparticles and MWCNTs-f-PANI, where the metal particles were present in a phase-pure crystalline state with face centered cubic (fcc) structure. The room temperature electrical conductivity of the MWNCTs-f-PANI/Au or Ag composites was 4.8–5.0 S/cm, respectively, which was much higher than that of CNTs-f-PANI (0.18 S/cm) or pure PANI (2.5 × 10^?3 S/cm). A plausible mechanism for the formation of nanocomposites is presented. We expect that the new synthesis strategy reported here will be applicable for the synthesis of other hybrid CNTs–polymer/metal nanocomposites with diverse functionalities. This new type of hybrid nanocomposite material may have numerous applications in nanotechnology, gas sensing, and catalysis.     

Ag/AgCl-decorated polypyrrole nanotubes and their sensory properties

A facile method to prepare Ag/AgCl-decorated polypyrrole nanotubes (PPy/Ag–AgCl nanocomposites) has been demonstrated. PPy nanotubes were assembled on the reactive self-degraded template of a fibrillar complex of FeCl₃ and methyl orange (MO). By introducing PPy nanotubes into AgNO₃ solution, Ag and AgCl nanoparticles could be uniformly decorated onto the PPy nanotube surface in situ by the reaction of PPy and AgNO₃. The morphology and structure of the nanocomposites were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The possible application of PPy/Ag–AgCl nanocomposites as a vapor sensor has also been reported. The responses of these nanocomposites were observed to be reversible by monitoring the change in the resistance of the nanocomposites upon exposure to ammonia vapor. PPy/Ag–AgCl composite nanotubes sensors showed enhanced chemiresistor sensitivity compared with PPy nanotubes.     

Preparation and properties of nanocomposites based on poly(lactic acid) and functionalized TiO2

Inorganic/polymer nanocomposites are significant materials due to their unique combination of properties. Lactic acid (LA) was used to modify the TiO₂ surface by the Ti-carboxylic coordination bonds, and LA can chemically bond TiO₂ nanoparticles to form functionalized oligomeric-poly(lactic acid)-grafted TiO₂ nanoparticles (g-TiO₂). The resulting g-TiO₂ was added to the poly(lactic acid) (PLA) matrix to prepare PLA/TiO₂ nanocomposites via melting processing. The structure and properties of the nanocomposites were subsequently investigated via Fourier transform infrared spectroscopy, gel permeation chromatography, scanning electron microscopy, transmission electron microscopy, polar optical microscopy, differential scanning calorimetry, dynamic rheometer and universal testing machine. The results showed that g-TiO₂ nanocomposites had a much lower degree of agglomeration than bare TiO₂. The introduction of g-TiO₂ into PLA matrix improved the crystallinity of the composites. The functionalized nanoparticles played an important role in improving mechanical properties and reducing the complex viscosity of the nanocomposites due to its unique structure and the reasonable interfacial interaction between the nanoparticles and PLA matrix.     

Preparation of oligoaniline derivative/polyvinylpyrrolidone nanofibers containing silver nanoparticles

Oligoaniline derivative/polyvinylpyrrolidone nanofibers containing silver nanoparticles have been successfully prepared by electrospinning technique. Silver nanoparticles were prepared through reduction of Ag⁺ by oligoaniline derivative, and the process of redox was monitored by UV–vis spectra. The morphology of Ag-polymer blends nanocomposites and the distribution of Ag nanoparticles were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical analysis of nanocomposites was checked by cyclic voltammetry (CV) in the 0.5 M H₂SO₄. In addition, the presence of Ag nanoparticles was indicated by X-ray diffractometer (XRD).     

载银自抛光 / 低表面能环保涂层的制备及其耐微生物附着性能研究

目的制备一种新型绿色环保的耐海洋微生物附着涂层。方法通过聚硅氧烷(有机硅)改性丙烯酸树脂,合成以硅氧烷为侧链,丙烯酸树脂为主链的有机硅改性丙烯酸树脂。利用聚多巴胺的粘附性和还原性,制备二氧化硅/聚多巴胺/纳米银(Si O2/PD/Ag)纳米复合材料。以制备的有机硅改性丙烯酸树脂为成膜物,以载银纳米颗粒为杀菌剂,制备耐微生物附着环保涂层。通过傅里叶红外光谱仪(FTIR)和接触角检测仪(CA)分别对有机硅改性丙烯酸树脂的Si—O基团和接触角作表征,通过透射电子显微镜(TEM)表征Si O2/PD/Ag的制备过程,通过水解率和细菌附着等实验评价涂层的防污性能。结果Si—O—Si和Si—O—C的接入使得丙烯酸树脂改性后的接触角从72°提高到96°。Si O2/PD/Ag是一种特殊"核-壳-卫星"结构的载银纳米颗粒,纳米银均匀分散在Si O2的表面。涂层的水解性能良好,水解率为1.03μm/d,杀菌剂分散均匀。结论该涂层通过自抛光和低表面能双重物理抑菌作用和纳米银的杀菌作用,能有效抑制海洋微生物在试样表面的附着。     

Influence of Ag doped graphene on electrochemical behaviors and specific capacitance of polypyrrole-based nanocomposites

In this work, silver (Ag) nanoparticles were deposited on graphene sheets by chemical reduction and Ag-doped graphene (Ag-GR)/polypyrrole (PPy) nanocomposites were prepared by oxidation polymerization. The effect of the Ag-GR incorporation on the electrochemical properties of the PPy nanocomposites was investigated. It was found that highly dispersed Ag nanoparticles (2–5 nm) could be deposited onto the GR and that Ag-GR was successfully coated by PPy. From the cyclic voltammograms, Ag-GR showed higher electrocatalytic activity than that of pristine GR. Furthermore, the Ag-GR/PPy showed remarkably increased current density, quicker response, and better specific capacitance compared with GR/PPy. This indicates that, due to their high electrocatalytic activity, the Ag nanoparticles deposited onto the GR serve as an efficiency catalyst to improve electrochemical performance of the GR/PPy and that they resulted in the increase of the charge transfer between GR and PPy by bridge effect.     

Microwave-assisted synthesis and magnetic properties of size-controlled CoNi/MWCNT nanocomposites

Size-controlled CoNi alloy nanoparticles with average diameters in the range of 15-48 nm attached on the multi-walled carbon nanotubes (MWCNTs) were prepared to form CoNi/MWCNT nanocomposites by microwave-assisted method. The size of CoNi alloy nanoparticles can be controlled through adjusting the atomic ratios of metals to carbon nanotubes in the mixed acetate solution. The as-prepared nanocomposites have been characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), energy-disperse X-ray spectroscopy (EDS) and vibrating sample magnetometer (VSM). The results show that CoNi alloy nanoparticles are face-centered cubic structure, quasi-spherical and disperse uniformly on the surface of MWCNTs. Magnetic measurement shows that both the coercivity and the saturation magnetization of the samples increase with the increase of the particle size from 15 to 37 nm, and decrease from 37 to 48 nm.     

Au/CdTe纳米复合材料的静电作用制备及表征(英文)

将相反电荷的纳米Au和纳米CdTe通过静电作用得到纳米复合Au/CdTe粒子。在水溶液中分别用二甲氨基吡啶和巯基丙酸稳定纳米Au和CdTe粒子,使其表面分别带有正电荷与负电荷。Au/CdTe纳米复合材料的表面等离子体吸收光谱随着Au含量的增加而红移,表明纳米复合Au/CdTe粒子的长大是由于配位形成而引起的。纳米Au和纳米CdTe的比影响纳米复合Au/CdTe粒子的结构。复合纳米Au/CdTe粒子的尺寸和形状是影响金属/半导体纳米复合材料性能的重要参数。用小角X射线散射技术、透射电子显微镜、循环伏安法和X射线光电子能谱来表征纳米复合Au/CdTe粒子。     

TiO2/PLCL可降解聚合物纳米复合材料的制备及形状记忆性能

制备TiO2/聚(L-丙交酯-ε-己内酯)(PLCL)纳米复合材料并研究其性能.采用ε-己内酯开环聚合法对TiO2纳米粒子进行表面改性,通过傅立叶变换红外光谱(FTIR)、热重分析(TGA)和透射电子显微分析(TEM)对聚己内酯(PCL)接枝改性后的TiO2纳米粒子(g-TiO2)进行表征.g-TiO2纳米粒子能均匀地分散在三氯甲烷溶液中.采用溶液浇铸的方法成功地制备了TiO2/PLCL复合材料.研究g-TiO2纳米粒子的含量对材料力学性能和形状记忆性能的影响.结果表明,5％ g-TiO2/PLCL复合材料的力学性能有显著的提高,与纯PLCL相比,抗拉强度提高了113％,伸长率提高了11％.含有g-TiO2纳米粒子的复合材料的形状记忆性能优于纯PLCL.g-TiO2纳米粒子具有物理交联作用,有助于形状记忆效应的提高.     

原位一步法合成Ag/Fe2O3磁性核壳纳米粒子

采用原位法在低温下一步合成Ag/Fe2O3磁性核壳纳米粒子,并采用XRD,TEM和UV光谱研究了Ag-Fe2O3核壳纳米复合材料的结构。结果表明,纳米银粒子表面被Fe2O3层包覆,Ag核的平均粒径大约为35nm,Fe2O3壳层平均厚度约为7.5nm或15nm,形成了核壳结构的电磁复合纳米粒子。在室温下,饱和磁化强度达到0.98(A·m2)·kg-1,矫顽力8.48×103A/m;Ag/Fe2O3核壳粒子的导电率达到0.62S/cm。通过此法可以比较容易的控制核和壳的尺寸以及复合粒子的单分散性,并得到较高的产率,在催化剂、医药、光电等领域有着广阔的应用前景。     

磁性Fe3O4/Ag复合纳米粒子制备与抗菌性能

采用箔-纤维-箔法和1150℃/150 MPa/30 min的真空热压工艺成功制备了SiCf/Ti-43Al-9V复合材料,并使用金相显微镜、X射线衍射仪、扫描电镜及能谱仪对该复合材料微观组织的形成进行了研究.结果表明,制备过程中SiC纤维与TiAl基体合金发生反应,并形成一定厚度的反应层;基体组织为等轴晶,粒径约为8 μm,与原始合金组织相比明显细化;从反应层到远处的TiAl基体合金,基体合金的组织由全γ相转变为α2/γ片层组织、γ晶粒和晶间B2相的混合组织.其中全γ相区域的厚度为2～4 μm,并围绕纤维分布.根据Ti-Al-V相图、C原子和V原子的扩散,分析了这两个基体区域的形成机理,并结合热压成形过程中的塑性变形和变形储存能,解释了基体合金晶粒大小的变化.     

Growth and Morphology Modulation of Needle-like Silicon Nanowires for SERS Application

半导体纳米线作为一种潜在的表面增强拉曼光谱（SERS）基底材料正受到广泛的关注。本文采用金作为催化剂,通过等离子体增强化学气相沉积系统,以气-液-固生长机制制备一种直径可控的针尖状硅纳米线。基于合金液滴控制硅纳米线形貌的事实,通过设计调节合金催化剂的尺寸,制备了针尖状硅纳米线。所制备硅纳米线形貌通过SEM清晰可见,为针尖状。TEM和XRD分析表明,硅纳米线为同轴结构,单晶硅核包覆非晶SiO2壳层。作为SERS活性基底,通过伽伐尼置换在纳米线表面沉积活性Ag颗粒,同等条件下对R6G的检测显示,针尖状硅纳米线基底其增强因子是柱状硅纳米线的十多倍。由此预测,这种针尖状的硅纳米线可应用于新型传感器、环境监测、生物医疗诊断等领域。此外,这种针尖硅纳米线的制备方法也可以用作制备其他的针尖状纳米线,例如同族的锗针尖纳米线等等。     

One-step preparation of silver nanoparticles confined in functionalized-free SBA-15 channels

Supported Ag nanoparticles were successfully prepared by a one-step in situ procedure within channels of SBA-15 mesoporous silica. The reaction was carried out in N,N-dimethylformamide (DMF) at 25 °C with no need for silica surface functionalization or demanding time-consuming steps, and presents important advantages over the usual method. The small-angle X-ray scattering (SAXS) pattern of SBA-15 presents well-defined reflections associated with P6mm hexagonal symmetry. TEM micrographs of supported Ag nanoparticles (SBA-15/Ag) clearly show the presence of spheroidal and elongated Ag nanoparticles that are confirmed by surface plasmon resonance band in the UV–vis absorption spectrum. No evidence of Ag nanoparticle agglomeration was observed throughout the inorganic matrix. Ag nanoparticle formation within channels of SBA-15 decreases its specific surface area and total pore volume, as evidenced by nitrogen adsorption–desorption isotherms, with no damage to the silica framework. The method shows itself to be very efficient, fast and convenient for the synthesis of supported Ag nanoparticles in SBA-15 channels.     

Ag/SiO2核-壳结构球的制备与光学性质

采用St(o)ber方法,以AgNO3与柠檬盐钠还原反应所制备出的Ag纳米颗粒为种子,合成了Ag/SiO2核-壳结构的亚微米球.用透射电镜(TEM)观测所得产物的形貌和大小,并用光吸收谱仪测试了Ag纳米颗粒的表面等离子体共振(SPR)引起的光吸收峰.     

一种无铼二代镍基单晶高温合金蠕变机制研究

利用层层静电自组装技术将聚乙烯亚胺(PEI-Ag+)、PdCl42-交替沉积在基底上,然后用硼氢化钠还原,构筑了含银/钯复合纳米粒子的PEI-Ag/Pd纳米复合薄膜.通过扫描电子显微镜(FESEM),X射线光电子能谱(XPS)和循环伏安(CV)等手段对复合膜的成分、微结构和性质进行了测试分析.膜上生成了不规则和立方体状的银/钯纳米复合物,导致膜表面有一定的粗糙度.结果表明,双金属{PEI-Ag/Pd}n复合膜比单金属{PEI/Pd}n或{PEI-Ag/PSS}n膜对多巴胺的氧化有更好的电催化活性.     

Enhanced Reflective Interference Spectra of Nanoporous Anodic Alumina Films by Double Electrochemical Deposition of Chemical Metal Nanoparticles

The effect of selective color reflection enhancement from a double metalized nanoporous anodic alumina (NAA) film surface under proper conditions of electrochemical and chemical metal (Cu—Ag, Cu—Au) deposition has been observed. Selective coloration of the NAA films with high index of the reflection and wide range of the color tones was achieved. The additional chemical deposition of the noble metal leads to the enhancement of the selective reflection ability and the interference contrast of the reflected light. The distribution of the chemically deposited silver nanoparticles on the top surface of electrochemically copper metalized pores of anodized aluminum has been shown by the electron microscopy method. The optical reflection spectra at different angles (10°-85°) of metalized NAA film have been measured, and the effective index of refraction (n ≈ 1.6) and film thickness have been calculated. The effect of the reflected light interference contrast enhancement has been explained as being a result of the more effective separation of the two reflecting surfaces air/Al₂O₃ in the structure of the film similar to a Fabry-Pérot interferometer.