有机金属化学气相沉积法制备的Ni/Al2O3纳米复合材料的氢吸附

研究了通过有机金属化学气相沉积技术及单源分子前躯体方法制备的Ni/Al₂O₃纳米复合材料的氢吸附(存储). 在冷壁的有机金属化学气相沉积反应器中,通过降解Ni(acac)₂粉末基底上的[H₂Al(OtBu)]₂制备的Ni/Al₂O₃纳米复合材料. 通过X射线粉末衍射、扫描电镜、透射电镜以及能量色散型X射线荧光光谱等技术表征该复合材料. 采用自制Sievert's设备研究该复合材料的氢吸附(存储),可以储存约2.9%(重量比)的氢.     

空心阴极辉光放电包覆铜纳米粉末

 简要叙述了自悬浮定向流方法制备铜纳米粉末的原理和包覆层薄膜的生长机理，采用空心阴极辉光放电对铜纳米粉末进行有机包覆，实验中CH4和H2的流量分别为6 ml/min和12 ml/min，工作电压为450 V，衬底与空心阴极的底端距离为2 cm，背景真空和工作气压分别为6 Pa和100 Pa，沉积速率为7.5 nm/min。用透射电镜(TEM)对铜纳米粉末进行了观察和分析，结果表明：铜纳米粉末呈球状，其粒径分布在10～100 nm之间, 平均粒径大小为50 nm；其包覆层的厚度大约为15 nm，而且该厚度可以通过调节空心阴极辉光放电的参数来控制。     

使用硫化物纳米前驱物墨水法制备铜铟硫薄膜

提出了一种通过反应烧结来制备CuInS₂多晶薄膜的低成本旋涂工艺路线．通过将前驱物粉末在氢气中预还原的方法来优化旋涂时使用的墨水成分,氢气还原会使前驱物纳米粉末从硫化物混合粉末转变成CuInS₂和Cu-In合金的混合物．扫描电子显微镜、电子能谱、X射线衍射以及拉曼图谱的结果表明,这种优化能极大的提高CuInS₂多晶薄膜的性能,其中包括薄膜的排列密度更高,杂质相减少,薄膜质量变得更好等．吸收光谱测得优化后的铜铟硫薄膜的带隙约为1.45 eV．     

刚性衬底上铜铟硒纳米棒阵列的合成与表征

在覆盖有钨电极的硅衬底上利用多孔阳极氧化铝模板为生长掩膜电沉积合成垂直排列的铜铟硒纳米棒阵列. 多孔阳极氧化铝模板由阳极氧化磁控溅射制备的铝膜制成. 扫描电子显微镜结果表明,该纳米棒阵列结构致密,直径约100 nm长度约1μm,纵横比为10. X射线衍射、微区拉曼光谱和高分辨透射电子显微镜结果表明,真空条件下450 oC退火处理的铜铟硒纳米棒是多晶纯相的黄铜矿结构的铜铟硒,在纳米棒轴向方向上有比较大的晶粒尺寸. 能量色散X射线光谱表明,铜铟硒纳米棒的化学组成接近InSe₂的化学计量比,由吸收光谱分析推算铜铟硒纳米棒带隙为0.96 eV.     

Ag60纳米颗粒[{Cl@Ag12}@Ag48(dppm)12]的结构(其中dppm=双(二苯基膦基)甲烷

本文合成一种新的双膦连接Ag₆₀纳米团簇[{Cl@Ag₁₂}@Ag₄₈(dppm)₁₂]，并通过X射线晶体学进行表征. 二十面体的银处于核心位置，里面是中心氯化物组成，外面有48 个银原子/离子的包裹，顶端是12个双(二苯基膦基)甲烷(dppm)配体. 同时利用密度泛函理论对阳离子[{Cl@Ag₁₂}@Ag₄₈(dppm)₁₂]⁺进行计算，以确定该结构是否对应于核心数n=58的超原子. DFT计算的优化结构与X射线一致，但是HOMO-LUMO的能差并不能保证其超级稳定性.     

γ射线辐射下制备聚苯胺/银纳米复合材料及其输运性质

在γ射线辐射下,采用一步法制备了聚苯胺/银复合材料,通过红外光谱、紫外-可见光光谱、X射线衍射分析表明,所制备的样品由聚苯胺和面心立方相的银组成. 反应机理研究表明,聚苯胺是通过苯胺阳离子与·OH反应生成的苯胺阳离子自由基之间的反应生成的,银是通过银Ag⁺与e^-_aq的反应生成的. 扫描电子显微镜和透射电子显微镜显示聚苯胺/银复合物呈纳米纤维和纳米颗粒的形貌,这种形貌可能是由于类似〝快速混合〞聚合反应的过程造成的. 在80～300 K,聚苯胺/银复合材料的输运行为可较好地符合变程跃迁模型,而在80 K以下,则明显地偏离变程跃迁模型.     

硼(氮、氟)掺杂对TiO2纳米颗粒光学性能的影响

利用X射线衍射谱、拉曼光谱和紫外-可见光吸收光谱研究了硼(氮、氟)掺杂对TiO₂纳米颗粒光学性能的影响.X射线衍射谱和拉曼光谱结果表明,掺硼(氮、氟)对TiO₂纳米颗粒的锐钛矿相晶体结构无明显影响,而其锐钛矿晶格出现畸变(c/a值增大),这被归因于掺杂原子对TiO₂纳米颗粒表面氧原子缺位沿晶格c轴方向的占据.另外,掺硼(氮、氟)TiO₂纳米颗粒吸收带红移与TiO相似文献   

低温固相反应法制备的NiFe2O4纳米颗粒的结构与磁性

采用低温固相反应法制备了晶粒尺寸在8—47nm之间的NiFe₂O₄纳米颗粒系列样品，用X射线衍射仪(XRD)、高分辨中子粉末衍射谱仪、振动样品磁强计和超导量子干涉仪等对样品的晶体结构、宏观磁性和纳米颗粒的表面各向异性进行了分析研究.XRD和中子衍射测量结果显示纳米颗粒的晶格常数略高于块体材料，样品的氧参量表明纳米颗粒的晶格畸变程度没有块体材料严重.相对块体材料，纳米颗粒具有较小的磁化强度、较大的矫顽力和各向异性能密度.纳米颗粒从多畴转变为单畴的临界尺寸约为40nm，超顺磁性临界尺寸约为16nm.     

电爆炸丝法制备纳米Al2O3粉末

 设计了电爆炸金属丝产生纳米金属氧化物粉末的实验装置，金属丝电爆炸腔采用圆筒结构，纳米粉末经过微孔滤膜过滤收集。成功制备了纳米Al₂O₃粉末，其平均粒度达到64.9 nm。对电爆炸金属丝产生纳米Al₂O₃粉末的物理条件进行了研究。结果表明实验条件对粉末粒度有重要影响：随气压的增加粉末平均粒度变大；随金属丝直径增大粉末平均粒度变大；粉末的平均粒度与电容器的初始储能也有一定的关系。     

Ag+掺杂的立方相Y2O3:Eu纳米晶体粉末发光强度研究

采用化学自燃烧法制备了不同Ag⁺掺杂浓度的Y₂O₃:Eu纳米晶体粉末样品(［Y³⁺］∶［Eu³⁺］∶［Ag⁺］=99∶1∶X，X=0—3.5×10^-2)，以及通过退火处理得到了相应的体材料.根据X射线衍射谱确定所得纳米和体材料样品均为纯立方相.实验表明在纳米尺寸样品中随着Ag离子浓度的增加，荧光发射强度随之增加，当X=2×10^-2时达到最大值，其发光强度比X=0时提高了近50%.当Ag离子浓度继续增加，样品发光强度保持不变.在相应的体材料样品中则没有观察到此现象.通过对各样品的发射光谱，激发光谱，X射线衍射图谱，透射电镜(TEM)照片和荧光衰减曲线的研究，分析了引起纳米样品荧光强度变化的原因是由于Ag离子与表面悬键氧结合，从而使这一无辐射通道阻断，使发光中心Eu³⁺的量子效率提高；Ag⁺的引入所带来的另一个效应是使激发更为有效.这两方面原因使发光效率得到了提高.     

Ag-Cu双金属团簇中Ag原子偏析行为的 分子动力学研究

采用了恒温分子动力学方法系统模拟研究了不同尺寸不同组分的Ag-Cu双金属团簇的退火过程。分析低温退火结构可得团簇中Ag原子的偏析行为：在Ag原子所占比率较少时，Ag原子全部占据在团簇表面；随着Ag原子数的增多，直到Ag和Cu的比率接近时，绝大多数Ag原子仍占据在团簇表面；这与实验观测Ag-Cu混合团簇中Ag原子的偏析行为完全一致。通过细致研究Ag-Cu双金属团簇中Ag原子的偏析行为与团簇尺寸、组分和温度的关系发现：当Ag原子所占比重明显少于Cu原子时，在各不同尺寸下，Ag原子偏析温度点均高于熔点，即在熔点以上一定温度范围内仍会出现Ag原子的偏析现象；当Ag原子所占比重明显多于Cu原子时，在各不同尺寸下，体系偏析温度点均低于团簇熔点；对于较大尺寸团簇，在Ag原子所占比重接近于Cu原子时，体系偏析温度点与团簇熔点相同。     

Fabrication and surface-enhanced Raman scattering (SERS) of Ag/Au bimetallic films on Si substrates

Ag films on Si substrates were fabricated by immersion plating and served as sacrificial materials for preparation of Ag/Au bimetallic films by galvanic replacement reaction. The formation procedure of films on the surface of Si was studied by scanning electron microscopy (SEM), which revealed Ag films with island and dendritic morphologies experienced novel structural evolution process during galvanic replacement reaction, and nanostructures with holes were produced within the resultant Ag/Au bimetallic films. SERS activity both of sacrificial Ag films and resultant Ag/Au bimetallic films was investigated by using crystal violet as an analyte. It has been shown that SERS signals increased with the process of galvanic substitution and reached intensity significantly stronger than that obtained from pure Ag films.     

Synthesis of bimetallic systems using replacement reactions

Series of bimetallic systems were prepared by replacement reactions and characterized by XRD and XPS. The results suggest that the ad-metals are monolayer dispersed on the surface of sub-metal in Pd(Pt, Cu)/Co(Ni) systems, while in Pd(Pt, Au)/Cu systems surface solid solution is formed. In Ag(Au)/Co(Ni) and Ag/Cu systems no interaction between the metals is observed just as in the simple mixture of the respective crystallites. The outermost electronic configurations, the atomic radius of the metals, and the low-preparation temperature seem to be important factors for the different states of these bimetallic catalysts.     

Study of luminescence and optical resonances in Sb2O3 micro- and nanotriangles

Bimetallic clusters display new characteristics that could not be obtained by varying either the size of pure metallic systems or the composition of bulk bimetals alone. Coating of pre-deposited clusters by vapour deposition is a typical synthesis process of bimetallic clusters. Here, we have demonstrated that hierarchical, gold cluster-decorated copper clusters as well as both heterogeneous and homogeneous Cu?CAu bimetallic clusters (4.6 to 10.7?nm) can be prepared by coating pre-deposited, size-selected Cu₅₀₀₀ (4.6?±?0.2?nm) with Au evaporation at various temperatures. These bimetallic clusters were analyzed by aberration-corrected scanning transmission electron microscopy and associated electron energy loss spectroscopy. The results indicate that the growth of bimetallic clusters is controlled by a competition between nucleation and diffusion of the coating Au atoms.     

Hydrophobic Bimetallic Catalysts for H/D Exchange Reaction between Hydrogen and Water

Hydrophobic bimetallic catalysts of Pt-M on styrenedivinylbenzene were prepared, where M represents successively: Ir, Rh, Pd, Cu and Ag. The total metal loading was 0.5 wt% and the weight fractions of the metal M were: 0.0,0.05,0.1,0.25,0.5,0.75 and 1.0. For each sample, the catalytic activity for H/D exchange between hydrogen and water vapor was measured. In case of monometallic catalysts, no activity was detected for M = Cu and M = Ag, and the order of the activity values for the other metals was: Pt < Ir < Rh < Pd. For each bimetallic catalyst, the activity measurements indicated a clear interaction between the platinum and the second metal, thus the activity was significantly increased for M = Ir, increased for M = Rh, decreased for M = Pd, drastically decreased for M = Cu and M = Ag.     

Ag–Cu/Pmma Nanocomposites Produced By Modification of PMMA with Bimetallic EEW-Nanoparticles

Russian Physics Journal - Using the method of electrical explosion of copper and silver wires in an argon atmosphere, Cu–94Ag, Cu–65Ag, and Cu–22Ag bimetallic nanoparticles are...     

Preparation of large-area surface-enhanced Raman scattering active Ag and Ag/Au nanocomposite films

Ag films on tinning glass substrates were fabricated by modified silver-mirror (Tollen’s) reaction with the advantage of low-cost, simple and quick fabrication process. The obtained Ag films were served as sacrificial materials for preparation of Ag/Au nanocomposite films by immersing in a chlorauric acid (HAuCl₄) solution at room temperature. After a short time of galvanic replacement reaction, Ag/Au bimetallic nanostructures were synthesized with “concave” structures. The morphology, properties and composition of the Ag and Ag/Au nanocomposite films were analyzed by using scanning electron microscopy (SEM), UV-visible spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectrometry (EDS) and surface enhanced Raman scattering (SERS). SEM images displayed that the large area of Ag film and Ag/Au bimetallic nanostructures experienced structural evolution process during galvanic reaction. The UV-Vis spectra showed the absorbencies characterization of Ag film and Ag/Au nanocomposite films. SERS measurements using methylene blue as an analyte showed that SERS intensities of bimetallic films were enhanced significantly compared with that of pure Ag films. The SERS enhancement ability of Ag/Au bimetallic films was dependent on the immersion time for galvanic replacement reaction.     

Optimization of surface coating condition using vapor form of alkanethiol on Cu nano powders for the application of oxidation prevention

There has been a growing interest in metal nano powders recently, and researches on Copper (Cu) nano particles are actively pursued due to its good electrical conductivity and its low prices. However, its easiness to oxidation and corrosion has delayed its research progress in Cu nano particles to be applied in inkjet printed electronics and other related research area. To overcome these problems, new surface coating method on Cu nano particles has been developed using dry process instead of conventional wet coating method. Octanethiol was used as a dry coating material because it has sulfur at the end of monolayer to chemically bond to the surface of fresh non-oxidized Cu nano particles to prevent oxidation. Octanethiol does not bond to oxidized surface of Cu nano particles. Previously, bonding between octanethiol and Cu nano particles, more specifically bonding between Cu surface and Sulfur (S) was analyzed using X-ray Photoelectron Spectroscopy (XPS). As a result, S peak was detected on the coated Cu nano particles, indicating that octanethiol chain has been successfully coated on the surface of Cu nano particles.In this study, optimization of dry coating condition was studied by varying coating time and cycles. XPS was used to analyze the composition of coated material to monitor the change in amount of S and O peaks for each condition. It was found that as the amount of Sulfur increased, the amount of Oxygen decreased and vice versa. This finding indicates that dry coating has suppressed the formation of oxygen on the surface of Cu nano powders by surrounding Cu surface with Sulfur end of octanethiol chain. Based on these experiments, the optimum coating condition for suppressing Cu oxidation was found to be 5 min and 6 cycles. For future work, the lifetime of octanethiol layer on the surface of Cu surface needs to be studied.     

Morphology and chemical state of PVP-protected Pt,Pt–Cu,and Pt–Ag nanoparticles prepared by alkaline polyol method

Well-dispersed, uniform monometallic Pt and bimetallic Pt–Cu, and Pt–Ag nanoparticles protected with PVP have been synthesized by a modified-protocol alkaline polyol method. The nanoparticles were characterized by various methods (TEM, XPS, and XRD) to elucidate the relationship between morphology and preparation variables. The average of monodispersed nanoparticles ranged between 4.1 and 4.9 nm. Core–shell structure was obtained in the case of bimetallic nanoparticles. The core of bimetallic nanoparticles was found to be rich in platinum, whereas the shell contained mostly copper or silver. The final structure of bimetallic nanoparticles was found to be determined by the morphology particles resulted in the first reduction step. Explanations are advanced on the light of experimental results.     

Electrophoreted Zn-TiO2-ZnO nanocomposite coating films for photocatalytic degradation of 2-chlorophenol

TiO₂-ZnO nano-powders with different TiO₂/ZnO ratios have been synthesized by hydrothermal method. Nanocomposite coating films consisting of TiO₂-ZnO and Zn with thickness of 20 μm have been electrophoreted on steel plates by rapid plating from a ZnO-based alkaline bath. X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis were used to investigate the structure, the size distribution, and the composition of prepared nano-powders and plated materials. The effect of the operating parameters such as powder contents, pH and current density on the electrophoresis process has been investigated and optimum conditions of coating process were determined. Corrosion properties of plated samples have been studied by salt spray test. The catalytic activity of the prepared nanocomposite Zn-TiO₂-ZnO films for the photocatalytic degradation of 2-chlorophenol (2-CP) was measured.