微纳级银包铜颗粒的快速制备及其导电性能

提出一种制备银包铜(Cu-Ag)核壳颗粒的一步化学置换法。使用成本较低的柠檬酸三纳(SC)作为还原剂和螯合剂,用明胶(Gelatin)作为分散剂,硫酸银(Ag_2SO_4)为Ag源,用一步化学置换法制备银包铜(Cu-Ag)核壳颗粒,研究了Ag_2SO_4和SC用量对Cu-Ag颗粒包覆效果和抗氧化性能的影响。结果表明,SC的剂量直接影响表面包裹的Ag颗粒形貌和均匀度。Ag_2SO_4剂量越大则Cu表面的Ag包裹量越大,导电性越好。当SC的剂量为1.5 g,Ag_2SO_4的剂量为8.0 g时Cu-Ag颗粒包覆效果好且电阻较低(仅为1.1Ω),因此可尽量降低Ag的消耗量提高颗粒的导电性。     

银基透明导电薄膜制备及其性能研究

采用磁控溅射方法制备了ZnO/Ag/ZnO、AZO/Ag/AZO三层和AZO/LiF/Ag/LiF/AZO、AZO/Al/Ag/Al/AZO五层透明导电薄膜,该体系薄膜450~700 nm的平均透过率在80%以上,方块电阻约5Ω/sq。插入LiF和Al的AZO/LiF/Ag/LiF/AZO和AZO/Al/Ag/Al/AZO导电薄膜在723 K退火后方块电阻分别为5.7Ω/sq和7.6Ω/sq,而AZO/Ag/AZO薄膜电阻快速上升到27Ω/sq。这表明五层结构的透明导电薄膜相比三层结构的导电薄膜明显的提高了热稳定性。可能原因是插入的LiF或Al层能抑制Ag原子的扩散和团聚。     

Ag包覆Fe3O4复合粉体的制备及其性能研究

用化学镀法,甲醛为还原剂,制备Fe3O4/Ag包覆复合粉体.用XRD、SEM和EDX对粉体进行表征.用重法测定粉体的抗氧化性能,并研究了AgNO3用量对Fe3O4/Ag包覆复合粉体的导电性能的影响.结果表明,用该法制备的Fe3O4/Ag包覆复合粉体能够实现表面银层包覆完整;Fe3O4粉镀银后的抗氧化性能得到一定程度的提高;AgNO3用量越多,Fe3O4/Ag包覆复合粉体的导电性能越好.     

核壳结构TiO2/Ag反蛋白石的制备与形貌观察

用化学还原法制备了银包覆聚苯乙烯(PS)微球结构,通过垂直沉积法排列出具有密堆积结构的PS-Ag蛋白石模板,然后采用溶胶-凝胶法渗透TiO2,最后焙烧处理除去PS,制备出了规整的核壳结构TiO2/Ag反蛋白石。采用扫描电镜、透射电镜和X射线衍射对该样品进行了分析。结果表明,PS球表面包覆的为纳米尺度的金属Ag;所制备的PS/Ag核壳微球蛋白石经过480℃、12h焙烧处理后获得的核壳TiO2/Ag反蛋白石结构的单胞参数可以通过调节包覆银层的厚度来调变,即改变AgNO3与PS球的质量比获得具有不同银包覆层厚度、不同单胞参数的三维蛋白石和反蛋白石结构。     

SiO2／Ag核壳复合粒子的制备与表征

首次引入活性SiO2微球作为核基，采用自组装液相还原技术，定向的在核基上沉积纳米银颗粒得到SiO2／Ag核壳复合粒子；并用红外、x射线衍射、场发射扫描电镜、能谱等分析表征该核壳复合粒子的形貌与结构。结果表明：利用活性SiO2作为核基，pH值为12．4，有表面活性剂参与的条件下，通过改变银前驱体浓度，可实现表面包覆致密、银壳厚度可控的核壳复合粒子化学制备技术。     

导电涂料中纳米铜粉抗氧化性的研究

为了提高纳米铜粉的抗氧化能力及其在聚合物基体中的分散性,在钠米铜粉表面包覆一层导电性和抗氧化性均佳的银.以水合肼为还原剂、PVP(聚乙稀吡咯烷酮)和硅烷偶联剂(KH-550)为分散剂,采用二月桂酸二丁基锡对纳米铜颗粒表面进行活化处理,然后采用置换反应法制备得到了与原纳米铜粉粒径和形貌大致相同的核壳型铜-银双金属粉末.采用X射线衍射(XRD)、XRF、TGA等手段分析了核壳铜-银双金属粉的抗氧化性能,并用透射电子显微镜(TEM)对粉末形貌进行表征.结果表明,经表面活化处理后得到的核壳铜-银双金属粉,在镀银质量分数较低(37.68%)时也能形成完全包覆型结构.包覆后的铜纳米颗粒在700℃以下没有任何氧化现象.     

核壳结构TiO2/Ag反蛋白石的制备与形貌观察

用化学还原法制备了银包覆聚苯乙烯(PS)微球结构,通过垂直沉积法排列出具有密堆积结构的PS-Ag蛋白石模板,然后采用溶胶-凝胶法渗透TiO2,最后焙 烧 处 理 除 去PS,制 备 出 了 规 整 的 核 壳 结 构TiO2/Ag反蛋白石。采用扫描电镜、透射电镜和X射线衍射对该样品进行了分析。结果表明,PS球表面包覆的为纳米尺度的金属银;所制备的PS/Ag核壳微球蛋白石经过480℃、12h焙烧处理后获得的核壳TiO2/Ag反蛋白石结构的单胞参数可以通过调节包覆银层的厚度来调变,即改变AgNO3与PS球的质量比获得具有不同银包覆层厚度、不同单胞参数的三维蛋白石和反蛋白石结构。     

Ag/AgX(X=Cl,Br)核壳复合粒子的制备及表征

通过使用3-巯基丙基三甲氧基硅烷对制备的球形卤化银进行表面处理,使其表面负载巯基,从而通过自组装液相还原技术,得到Ag/AgX核壳复合粒子。并用红外光谱分析、X射线衍射、能谱分析和扫描电镜等方法分析表征该核壳复合粒子的表面基团、组分、形貌与结构。详细研究了巯基处理前后和光照对Ag/AgX核壳复合粒子的影响。结果表明:当使用3-巯基丙基三甲氧基硅烷对制备的球形卤化银进行表面处理,通过液相还原可以生成银颗粒包覆致密的Ag/AgX核壳复合粒子,并且证明了Ag/AgX核壳复合粒子在光照条件下具有较好的稳定性。     

纳米尺度PS/Ag核壳结构复合球的制备与表征

采用分步法制备了聚苯乙烯/银(PS/Ag)核壳结构复合纳米球。首先采用无皂乳液聚合法并利用丙烯酸(AA)的羧基对制备的PS球进行改性,使其表面带负电荷;然后通过静电吸附作用在改性PS球的表面沉积[Ag(NH3)2]+,水浴(80℃)环境中利用十二烷基磺酸钠(SDS)作为还原剂将PS球表面的[Ag(NH3)2]+还原,制备出PS/Ag核壳结构复合球。通过动态激光粒度分析仪和透射电子显微镜对PS/Ag核壳纳米球的粒度分布、形貌和结构进行了表征,研究了AA的用量对复合球粒径及包覆的Ag壳厚度的影响。结果表明,随着AA用量的增大,所包覆的银层更加致密,厚度增大,当AA用量为15%时可得到Ag完全包覆的PS/Ag复合纳米球。     

介孔SiO2负载和包覆的纳米金属颗粒的制备与研究

制备了以SiO2为核、介孔SiO2为壳的核-壳颗粒负载纳米金属颗粒以及介孔SiO2壳层包覆SiO2负载的纳米金属颗粒。结果表明,十六烷基三甲基溴化胺(CTAB)作为模板剂,有助于介孔SiO2壳层包覆SiO2核的结构形成,介孔SiO2壳层的孔径方向垂直于SiO2核的表面;在聚乙烯吡咯烷酮(PVP)的稳定作用下,Pt纳米颗粒能均匀地分布在介孔SiO2壳层的表面。单分散SiO2颗粒经过3-氨丙基三乙氧基硅烷(APS)功能化后,可负载纳米金属颗粒。进一步研究表明,以SiO2负载纳米金属颗粒为核,NH3.H2O,乙醇和水为分散剂,CTAB为模板剂,正硅酸乙酯(TEOS)为硅源,还能制备介孔SiO2壳包覆SiO2负载的纳米金属颗粒,而且介孔SiO2壳层的厚度可通过TEOS的含量调节。     

Synthesis of highly environmental stable copper–silver core–shell nanoparticles for direct writing flexible electronics

In this study, Cu@Ag core–shell nanoparticles (NPs) with highly environmental stability were synthesized successfully by combining the NaBH₄ reduction method with the transmetallation reaction, and the Cu@Ag nano-ink was prepared for direct writing flexible electronics. The structure, component, thermal stability and oxidation resistance of Cu NPs and Cu@Ag core–shell nanoparticles were characterized and discussed systematically. The results showed that Cu NPs could be obtained via the reduction of Cu²⁺ ions by using cetyltrimethylammonium bromide (CTAB) as a dispersing agent under an excess of sodium hydroxide (NaOH) and sodium borohydride (NaBH₄) in aqueous solution. And the Cu@Ag core–shell nanoparticles with uniform Ag shell and Cu core can be fabricated with the transmetallation reaction that Ag⁺ ions were reduced by the copper atoms on the surface of Cu NPs at pH 7, and the Cu core were kept from oxidation from the Ag shell. Besides, Cu@Ag nano ink were fabricated by dispersing Cu@Ag core–shell nanoparticles in ethylene glycol, and Cu@Ag conductive pattern were directly drawn on ordinary photo paper using a roller pen filled with 30 wt% Cu@Ag nano ink. The electrical resistivity of the conductive Cu@Ag pattern obtained from the nano ink was as low as 13.8 μΩ cm^?1 due to the continuous interconnections between the nanoparticles established when thermal sintered at 150?°C for 1 h under N₂. When the conductive wires of a lamp were connected to the two ends of the written conductive line, the lamp was illuminated immediately. It demonstrated that the complicated Cu@Ag nano-ink pattern had very good conductivity and applicability. This work provides an effective approach to prepare Cu@Ag core–shell nano-ink for direct writing flexible electronics.     

纳米Ag链的制备及其在聚氨酯基柔性导电复合材料中的应用

针对柔性聚合物基导电复合材料的导电性差和柔性差这2个关键问题,分别从导电填料的柔性化及降低填料含量2方面着手,以脱氧核糖核酸（DNA）大分子链作为模板,制备了大小均一、链状排列的柔性纳米Ag链及纳米Ag链填充的聚氨酯基柔性导电复合材料。利用SEM对纳米Ag链/Ag包Cu粉/聚氨酯导电复合材料的界面结构进行了表征,探讨了纳米Ag链/Ag包Cu粉/聚氨酯导电复合材料导电性及柔性的机制。研究发现:保持导电填料总质量分数为76%、纳米Ag链的质量分数为4%时,纳米Ag链/Ag包Cu粉/聚氨酯导电复合材料的电阻率及形变前后的电阻变化比值达到最佳值,分别为2.13×10-4 Ω·cm和3.6;当以纳米Ag链为单一填料时,制得的纳米Ag链/聚氨酯导电复合材料具有优异的柔性;泡沫法制备的纳米Ag链/聚氨酯导电复合材料可以在低填料质量分数时达到更高的导电性,当纳米Ag链质量分数为60%时,方阻为56 Ω/sq,低于共混法制备的填料质量分数为65%时的纳米Ag链/聚氨酯导电复合材料（98 Ω/sq）。      

Preparation of Ag nanospheres filled with Cu

Surface properties of Ag nanoparticles may not be perturbed when they are filled with the relatively cheap Cu. To better understand how Ag can be coated on Cu, growth of the Cu and Ag bimetal during the temperature-programmed carbonisation (TPC) of Ag⁺- and Cu²⁺-β-cyclodextrin (CD) complexes having the Cu/Ag ratios of 0.5, 1 and 2 was studied by in situ synchrotron small angle X-ray scattering (SAXS) spectroscopy. The SAXS spectra provide the detailed structural changes corresponding to the growth of Ag and Cu nanoparticles as the Ag⁺- and Cu²⁺-CD complexes are carbonised at the temperature range of 363–513 K. It seems that Cu having a relatively high surface free energy is enriched in the core of the cherry-like Cu@Ag bimetal nanoparticles. The Cu@Ag bimetals are encapsulated in the carbon-shell formed from carbon unconsumed in the oxidation of CD during TPC. A rapid growth of the bimetal nanoparticles occurs at 393–423 K. As Ag⁺ and Cu²⁺ are reduced during the CD oxidation, the Ag nanospheres are filled with Cu, and eventually encapsulated in the carbon-shell. Note that the carbon-shell coated on Cu@Ag can be removed by steam reforming at 573 K.     

Effects of silver nanowire concentration and annealing temperature on the optoelectronic properties of hybrid transparent electrodes

In this study, Ag nanowire (AgNW) was used to fabricate ITO/AgNW/ITO (IAI) and ZnO/AgNW/ZnO (ZAZ) hybrid transparent electrodes. The covered area ratio of AgNW showed that when AgNW concentration n _AgNW ≥ 2.0 mg/mL, AgNW easily agglomerated during the spin-coating. Meanwhile, Haacke index and haziness measurements also indicated that for application with high optical demands, the AgNW concentration should be ≤2.0 mg/mL for both ZnO or ITO systems. In this study, when n _AgNW = 2.0 mg/mL, the sheet resistant of ZAZ electrodes was 10.5 Ω/sq while the transmittance (including glass) was 72.7% in the visible region. For IAI electrodes, the sheet resistant was 18.8 Ω/sq and transmittance (including glass) was 78.2% in the visible region. Further analysis implied that the sheet resistance of hybrid electrodes could be as low as 10 Ω/sq by optimizing AgNW distribution as well as using suitable annealing techniques.     

Direct nucleation of silver nanoparticles on graphene sheet

Silver (Ag) nanoparticles were synthesized on the surface of graphene sheet by the simultaneous reduction of Ag+ and graphene oxide (GO) in the presence of simple reducing agent, hydrazine hydrate (N2H4 x H2O). Both the Ag+ and GO were reduced and Ag+ was nucleated onto graphene. GO flakes were prepared by conventional chemical exfoliation method and in the presence of strong acidic medium of potassium chlorate. Silver nanoparticles were prepared using 0.01 M AgNO3 solution. The reduced GO sheet decorated with Ag is referred as G-Ag sample. G-Ag was characterized by FTIR (Fourier transform infrared) spectroscopy using GO as standard. An explicit alkene peak appeared around 1625 cm(-1) was observed in G-Ag sample. Besides, the characteristic carbonyl and hydroxyl peaks shows well reduction of GO. The FTIR therefore confirms the direct interaction of Ag into Graphene. SEM (scanning electron microscopy) and TEM (transmission electron microscopy) analysis were performed for morphological probing. The average size of Ag nanoparticles was confirmed by around 5-10 nm by the high-resolution TEM (HRTEM). The Ag quantum dots incorporated nanocomposite material could become prominent candidate for diverse applications including photovoltaic, catalysis, and biosensors etc.     

Cu基Al掺杂ZnO多层薄膜的生长及其性能

本文采用直流磁控溅射技术在玻璃衬底上制备了AZO/Cu、Cu/AZO和AZO/Cu/AZO三种复合结构多层膜,研究了生长温度对多层膜特性的影响,发现AZO/Cu双层薄膜具有最优的光电性能,其最佳生长温度为100~150℃。文中进一步考察了生长温度对AZO/Cu双层薄膜结构性能和表面形貌的影响,结果表明：合适的生长温度有...     

Influence of copper morphology in forming nucleation seeds for graphene growth

We report that highly crystalline graphene can be obtained from well-controlled surface morphology of the copper substrate. Flat copper surface was prepared by using a chemical mechanical polishing method. At early growth stage, the density of graphene nucleation seeds from polished Cu film was much lower and the domain sizes of graphene flakes were larger than those from unpolished Cu film. At later growth stage, these domains were stitched together to form monolayer graphene, where the orientation of each domain crystal was unexpectedly not much different from each other. We also found that grain boundaries and intentionally formed scratched area play an important role for nucleation seeds. Although the best monolayer graphene was grown from polished Cu with a low sheet resistance of 260 Ω/sq, a small portion of multilayers were also formed near the impurity particles or locally protruded parts.     

Synthesis of beta-cyclodextrin-modified water-dispersible Ag-TiO2 core-shell nanoparticles and their photocatalytic activity

The beta-cyclodextrin-modified Ag-TiO2 core-shell nanoparticles were prepared by sodium borohydrate reduction of AgNO3 and the subsequent hydrolysis of the tetraisopropyl orthotitanate in an aqueous medium. Inversely in the preparation of beta-cyclodextrin-modified TiO2-Ag core-shell nanoparticles, first hydrolysis and then following reduction were carried out. The synthesized spherical core-shell nanoparticles were highly water-dispersible and had an average diameter in the range of 9 to 12 nm. A significant shifting of surface plasmon band was observed for the synthesized Ag-TiO2 and TiO2-Ag core-shell nanoparticles. On a model reaction, namely, the photodegradation of phenol by the UV light irradiation, the photocatalytic property of TiO2 nanoparticles was enhanced, when the Ag nanoparticle was embedded in the core of TiO2 nanoparticles but TiO2 nanoparticles coated by Ag shell decreased the photocatalytic property of TiO2 nanoparticles. The mechanism is ascribed to the surface plasmon characteristics of Ag in the core of the TiO2 nanoparticles under the acceleration by host-guest inclusion characteristics.     

Facile synthesis of near-monodisperse Ag@Ni core-shell nanoparticles and their application for catalytic generation of hydrogen

Magnetically recyclable Ag-Ni core-shell nanoparticles have been fabricated via a simple one-pot synthetic route using oleylamine both as solvent and reducing agent and triphenylphosphine as a surfactant. As characterized by transmission electron microscopy (TEM), the as-synthesized Ag-Ni core-shell nanoparticles exhibit a very narrow size distribution with a typical size of 14.9 ± 1.2 nm and a tunable shell thickness. UV-vis absorption spectroscopy study shows that the formation of a Ni shell on Ag core can damp the surface plasmon resonance (SPR) of the Ag core and lead to a red-shifted SPR absorption peak. Magnetic measurement indicates that all the as-synthesized Ag-Ni core-shell nanoparticles are superparamagnetic at room temperature, and their blocking temperatures can be controlled by modulating the shell thickness. The as-synthesized Ag-Ni core-shell nanoparticles exhibit excellent catalytic properties for the generation of H(2) from dehydrogenation of sodium borohydride in aqueous solutions. The hydrogen generation rate of Ag-Ni core-shell nanoparticles is found to be much higher than that of Ag and Ni nanoparticles of a similar size, and the calculated activation energy for hydrogen generation is lower than that of many bimetallic catalysts. The strategy employed here can also be extended to other noble-magnetic metal systems.     

Synthesis and characterization of low temperature Sn nanoparticles for the fabrication of highly conductive ink

To fabricate a low cost, highly conductive ink for inkjet printing, we synthesized a gram scale of uniformly sized Sn nanoparticles by using a modified polyol process and observed a significant size-dependent melting temperature depression from 234.1?°C for bulk Sn to 177.3?°C for 11.3 nm Sn nanoparticles. A 20 wt% of Sn nanoparticles was dispersed in the 50% ethylene glycol: 50% isopropyl alcohol mixed solvent for the appropriate viscosity (11.6 cP) and surface tension (32 dyn cm(-1)). To improve the electrical property, we applied the surface treatments of hydrogen reduction and plasma ashing. The two treatments had the effect of diminishing the sheet resistance from 1 kΩ/sq to 50 Ω/sq. In addition, conductive patterns (1 cm × 1 cm) were successfully drawn on the Si wafer using an inkjet printing instrument with conductive Sn ink. The maximum resistivity for an hour of sintering at 250?°C was 64.27 μΩ cm, which is six times higher than the bulk Sn resistivity (10.1 μΩ cm).