银元素的循环实验

设计并完成了由5步构成的银元素的循环实验,从银粉出发,经过银在硝酸中溶解,银离子与氯离子反应生成氯化银沉淀,氯化银溶解于氨水,银氨络离子与乙炔反应生成乙炔银,水合肼将乙炔银还原为单质银等化学反应,完成了银的循环实验。     

Idiosyncratic Ag7Pt2O7: An Electron Imprecise yet Diamagnetic Small Band Gap Oxide

The seminal qualitative concepts of chemical bonding, as presented by Walter Kossel and Gilbert Newton Lewis back in 1916, have lasting general validity. These basic rules of chemical valence still serve as a touchstone for validating the plausibility of composition and constitution of a given chemical compound. We report on Ag₇Pt₂O₇, with a composition that violates the basic rules of chemical valence and an exotic crystal structure. The first coordination sphere of platinum is characteristic of tetravalent platinum. Thus, the electron count corresponds to Ag₇Pt₂O₇*e⁻, where excess electrons are associated with the silver substructure. Such conditions given, it is commonly assumed that the excess electrons are either itinerant or localized in Ag−Ag bonds. However, the material does not show metallic conductivity, nor does the structure feature Ag-Ag pairs. Instead, the excess electrons organize themselves in 2e−4c bonds within the silver substructure. This subvalent silver oxide reveals a new general facet pertinent to silver chemistry.     

Influence of Temperature and Time on the Stability of Silver in Silica Sol-Gel Glasses

The darkening of silica sol-gel glasses doped with 0.05 mol% silver was studied. Six sols were prepared from TEOS and silver nitrate. Different additives were used, to influence the chemical and physical states of silver: oxidizing or reducing agents (H₂O₂, As₂O₅), colloid stabilizer (sodium citrate) and network modifiers (Li₂O, CaO). Sols were gelified at 60°C and densified at 600°C. The samples without additives and those prepared with H₂O₂ at room temperature even if they were protected from light. With increased temperature, the darkening became samples were heated above, 400°C, reversible bleaching took place. This darkening-bleaching is of thermal nature (“thermochromic effect”) and seems to be determined by a reversible aggregation-disaggregation of tiny silver particles. The presence of sodium citrate, as an additive delayed the darkening effect and the presence of CaO delayed it even further. Lithium oxide inhibited it totally.     

In-Situ Formation of AgCl Nanocrystallites in Films Prepared by the Sol-Gel and Silver Nanoparticles in Silica Glass Films

We are reporting on a novel preparation of silver chloride in sol-gel silica films as a precursor for nanoparticles of silver. The precipitation of silver chloride particles in-situ was achieved by the reaction of silver nitrate with trichloroacetic acid. The reaction leads to a slow release of chloride leading to a controlled precipitation of AgCl. The existence of an isotropic crystalline AgCl phase in the glass films was demonstrated by X-rays Diffraction Analysis (XRD) and Scanning Electron Microscope and Energy Dispersive Analysis of X-rays (SEM-EDAX). The resulting films are of good optical quality and exhibit a strong coloration upon irradiation with sunlight or heating to 600°C, due to the reduction of AgCl to silver nanoparticles. The absorption spectra of the films before and after irradiation are shown.     

银/聚合物纳米复合材料

银/聚合物纳米复合材料是一种典型的聚合物基复合材料, 其结构和性能依赖于合成方法,因此开发材料的优异性能必须以深入研究纳米材料的先进合成技术为前提。本文综述了纳米银粒子及其与聚合物形成的纳米复合材料的最新合成进展, 重点介绍了基于液相化学还原方法合成纳米银粒子的新方法, 如溶胶-凝胶法、沉淀法、微乳液法和离子液体法, 以及纳米银粒子的分散技术和原位法合成银/聚合物纳米复合材料的新技术, 并介绍了纳米银复合材料的电绝缘性、表面增强拉曼散射性能、抗菌性及其在生物医学等领域中的应用。     

单分散性银纳米粒子的可控制备

以卤化银或氧化银作为前驱体,室温下以水为溶剂,在较高溶液浓度下,利用化学还原法制备了单分散性银纳米粒子,并通过改变前驱体的种类,实现了粒径可控制备。采取扫描电子显微镜（SEM）、紫外-可见光谱仪（UV-Vis）、X射线-粉末衍射仪（XRD）、X射线-光电子能谱仪（XPS）等对所制备的银纳米粒子的形貌及成分进行了表征。结果显示,所制备的银纳米粒子具有较高的单分散性,粒径在40~150 nm之间,具有面心立方多晶结构。该方法制备的银纳米粒子可用于喷墨打印RFID天线。     

Fabrication of a Simple and Cheap Screen-printed Silver/Silver Chloride (Ag/AgCl) Quasi-reference Electrode

In this work, a silver/silver chloride ink is fabricated using two steps. First the silver ink is prepare using silver, nail polish and acetone. Then the silver ink is painted in a paper substrate and a silver chloride layer is deposited using a bleach solution. The result is the silver/silver chloride conductive ink. The silver ink is cheap ($2.49/g), well-dispersive and very easy to fabricate. The materials were characterized by SEM and XRD. The Ag ink showed the formation of a continuous network throughout the silver ink film with fewer agglomeration. The effective chlorination process was also observed in the Ag/AgCl characterization. Since the Ag/AgCl substrate will be used as a quasi-reference electrode, it is important to investigate the electrical properties. The Ag ink showed an average ohmic resistance of 2.27 Ω. The addition of the AgCl layer decreases the conductivity, as expected. In summary, the Ag/Ag/Cl ink developed is simple, well-dispersed, cheap and with good conductivity. Therefore, it can be used as a conductive ink in the fabrication of quasi-reference electrodes.     

银纳米微球和银纳米棒自组装膜的制备及SERS研究

采用硼氢化钠还原硝酸银,用振荡器在不同转速下振荡得到单分散的银纳米微球和银纳米棒,再将银纳米微球及银纳米棒自组装于被3-氨丙基-三甲氧基硅烷(APTMS)修饰的玻璃基片上,制得了具有表面增强拉曼(SERS)活性的基底,分别以罗丹明6G(R6G)和罗丹明B(RB)为探针分子对这两种基底进行SERS活性检测,结果发现这两种基底均为较理想的SERS衬底。     

A study of the silver form of a natural zeolitic material of the clinoptilolite type

The silver forms of a natural zeolitic material (from the East Slovakian deposit) on the clinoptilolite type has been prepared. The silver forms of the natural zeolitic material were investigated by X-ray powder diffractometry, IR spectroscopy, ESCA measurements, scanning electron microscopy and conductivity measurements. Depending on the preparation conditions, the content of silver ions in the zeolitic products was found to be in the range from 16 to 24%. In the sample with a silver loading of 18.6%, the silver uptake is due to an ion exchange process, mostly involving Na(I), Ca(II) and Mg(II) ions.     

Influence of SO2 on the durability of Ag/Al2O3 catalyst in lean NOx reduction by ethyl alcohol

The influence of SO₂ (200 ppm) on the durability of a Ag/Al₂O₃ catalyst for the reduction of NOx with ethyl alcohol was examined. The results strongly suggest that H₂O in diesel engine exhaust is essential for the high durability of Ag/Al₂O₃ catalyst in the presence of SO₂.     

Sonochemical Synthesis of Ag/AgCl Nanocubes and Their Efficient Visible‐Light‐Driven Photocatalytic Performance

A novel one‐step sonochemical approach to synthesize a plasmonic photocatalyst of AgCl nanocubes (ca. 115 nm in edge length) with a small amount of Ag metal species is presented. The nanoscale Ag/AgCl hybrid photocatalysts with cubic morphology are readily formed under ambient ultrasonic conditions and neither external heat treatment nor reducing agents are required. The size of the Ag/AgCl photocatalysts could be controlled by changing the concentrations of Ag⁺ ions and polyvinylpyrrolidone molecules in precursor solutions. The compositions, microstructures, influencing factors, and possible growth mechanism of the Ag/AgCl hybrid nanocubes were systematically investigated. The Ag/AgCl photocatalysts show excellent photocatalytic performance for degradation of various dye molecules under visible light.     

Electrochemical Nanoparticle Sizing Via Nano-Impacts: How Large a Nanoparticle Can be Measured?

The field of nanoparticle (NP) sizing encompasses a wide array of techniques, with electron microscopy and dynamic light scattering (DLS) having become the established methods for NP quantification; however, these techniques are not always applicable. A new and rapidly developing method that addresses the limitations of these techniques is the electrochemical detection of NPs in solution. The ‘nano-impacts’ technique is an excellent and qualitative in situ method for nanoparticle characterization. Two complementary studies on silver and silver bromide nanoparticles (NPs) were used to assess the large radius limit of the nano-impact method for NP sizing. Noting that by definition a NP cannot be larger than 100 nm in diameter, we have shown that the method quantitatively sizes at the largest limit, the lower limit having been previously reported as ∼6 nm.¹     

混合银盐的光敏热成像材料感光性能研究

本文以原位法合成的AgBrI作为光敏剂,亲水型的聚乙烯醇为粘合剂,考察了以苯并三氮唑银和4-羟基-6甲基-1,3,3a,7-四氮茚银混合银盐为银源的光敏热成像材料的感光性能,实验结果表明:含AgTAI的混合银盐的PTG材料感光性能明显好于单纯AgBTA的PTG材料.通过光敏热成像材料乳液pH值pAg值测定及银盐DSC分析,认为混合银盐能够提高PTG材料感光性能的原因是其溶解度比AgBTA的溶解度大,能够提供充足的Ag⁺,增大显影密度,提高反差,且混合银盐颗粒尺寸小,其比表面积大,能够充分接触超细卤化银颗粒,从而促进热显影的进行.     

New silver tellurite glasses

The glass forming ranges in the TeO₂-AgO_0.5 and TeO₂-AgO_0.5-AgI systems have been assessed for two cooling rates; results based on heat capacity and electrical conductivity measurements as well as derived from infrared spectroscopy are presented. The ternary glasses are excellent conductors due to the presence of Ag⁺ ions mainly supplied by AgI. The decrease in C _P with increasing AgI-content suggests the presence of AgI microdomains which are finely distributed and do not contribute to the configurational heat capacity change. Fast motion of Ag⁺ ions (low activation energy) occurs in the glassy matrix which shows slow structural relaxation (high activation barrier).This research is performed within the frame of a P.I.R.M.A.T. action of the CNRS.     

Preparation and Characterization of a Composite of Silver Iodide and Synthetic Mordenite

A composite material made up of AgI and the potassium form of mordenite has been prepared by treating the silver form of synthetic mordenite with potassium iodide. The composite as well as the silver and potassium forms of mordenite have been characterised by X-ray powder diffractometry, X-ray photoelectron spectroscopy, EDS analyses and ac conductivity measurements. It has been inferred that, in the composite material, AgI grows at the entrance of the zeolite channels without forming a continuous conducting phase. The silver form of mordenite has been proved to be a silver ion conductor by dc conductivity measurements.     

Photochromic Coatings Containing Ag(Cl1−xBrx) Microcrystals

Photochromic ormosil coatings containing Ag(Cl_1–x Br _x ) microcrystals were formed on a glass substrate via the sol-gel process. Methyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane were used as starting materials of the ormosil matrices. 3-chloropropyltrimethoxysilane and bromophenyltrimethoxysilane were added as halogen sources and silver colloidal dispersion was introduced into the precursor sol. The coated glass became transparent and photosensitive after Ag(Cl_1–x Br _x ) microcrystals were precipitated in the coatings above 300°C. Insertion of a SiO₂ buffer layer between the substrate and photochromic layer was effective in preventing Ag⁺ migration into the substrate. Photochromic performances were improved by the substitution of Cl with Br and the incorporation of a minute amount of Cu.     

Immunoassay based on peroxidase silver conjugate for the determination of human immunoglobulins against tick-borne borreliosis (lyme disease) by voltammetry and spectrophotometry

In this work two strategies for the synthesis of peroxidase silver conjugates for the qualitative and quantitative determination of immunoglobulins (IgG) to ixodid tick-borne borreliosis (ITBB) (Lyme disease) in human serum were proposed. The first approach for Ab-HRP@AgNP conjugate synthesis involved silver nanoparticles (Ag NPs) capped with a commercial peroxidase conjugate (Ab-HRP) by passive adsorption. The second strategy was based on the initial coupling of Ag NPs with human anti-species antibodies (Ab) by passive adsorption followed by the introduction of horseradish peroxidase (HRP) enzyme into the reaction mixture as a blocking reagent for Ab@AgNP@HRP conjugate synthesis. The formation of peroxidase silver conjugates was proved by UV/Vis spectroscopy and Transmission Electron Microscopy (TEM). The catalytic activity of Ab-HRP@AgNP and Ab@AgNP@HRP conjugates was evaluated by Michaelis-Menten kinetics. A commercially available 96-well microtiter plate with recombinant antigens to ITBB was used as a platform for immobilization of analyzed IgG. The HRP in Ab-HRP@AgNP conjugate was found to retain a sufficient level of activity for interaction with the H₂O₂ substrate to form an intensely colored reaction product. Therefore Ab-HRP@AgNP conjugate can be used in enzyme-linked immunosorbent assay (ELISA) with spectrophotometric detection of 3,3’,5,5’-Tetramethylbenzidine (TMB Ox) for quantitative determination of IgG to ITBB in human serum in the concentration range 12.5–800 ng ml⁻¹ with LOD 2 ng ml⁻¹. Ab@AgNP@HRP conjugate is recommended for the electrochemical determination of IgG to ITBB in human serum at LOD 3 ng ml⁻¹ with registration of silver oxidation by linear sweep anodic stripping voltammetry (LSASV). Ag NPs in Ab-HRP@AgNP and Ab@AgNP@HRP conjugates do not change electrochemical activity during storage and can be used as an electrochemical label in LSASV method in case of HRP inactivation. The immunoassay based on peroxidase silver conjugates expands the analytical potential for the determination of IgG to ITBB especially during the period of increasing incidence.     

制取银氨溶液异常实验现象的探究

将市售硝酸银试剂配成溶液,滴入氨水,反应液始终保持澄清,初步认为这种异常实验现象是由硝酸银试剂中含有少量硝酸铵杂质引起的。测定了向硝酸银溶液中加入氨水生成氧化银沉淀的质量,指出制取银氨溶液时只有少部分硝酸银与氨水反应生成中间产物氧化银,大部分硝酸银与氨水反应直接生成银氨络合物。探析了向硝酸银溶液中滴入氨水,反应液始终澄清或生成白色沉淀的异常实验现象。     

Synthesis of silver nanoparticles in mesoporous high-aluminum aluminosilicate matrices

A new method for the synthesis of Ag/Al_xSi_1–x O_2–0.5x nanocomposite materials was proposed. The method is based on the use of charged mesoporous aluminosilicate matrices as nanoreactors. The porous structure of the matrices was characterized by ²⁷Al NMR spectroscopy and nitrogen capillary sorption at 77 K. An increase in the aluminum loading destroys the matrix structure and decreases the specific surface area. The resulting aluminosilicates were used as matrices for the synthesis of silver nanoparticles. The nanocomposites were examined by transmission electron microscopy and chemical analysis to estimate the silver percentage in specimens. Silver nanowires (20% Ag) are formed in the low-aluminum (<10 mol.%) matrices, whereas an increase in the aluminum percentage affords both nanowires and spherical particles 3–10 nm in size and decreases the total amount of silver in the nanocomposite.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2391–2393, November, 2004.     

基于羧酸银的光敏热成像技术进展

最近10年,光敏热显影成像材料在技术上取得了重要进展,特别是以羧酸银作为银源的这类材料.这些进展集中体现在1995年为满足商品需要而研制成功的世界上第一个具有高分辨力、可作诊断使用的医用X射线胶片的Kodak DryView激光成像片上.此后,采用同样技术的一类特殊片种,即高反差的印刷胶片也随之问世.这些产品的实践应用都相当成功,已被多家公司所采用.这些新产品得益于三个方面的技术进展:改进成像层的照相性质、高影像质量和低成本的激光成像硬件,这也是此研究工作的焦点.在这类材料上所取得的重要成就反映在它们的高分辨力、高最大密度、低最小密度以及整张胶片性质的均一性上.所有这些优点,再加上超过100年的影像稳定性,使原来“老”的光敏热显影技术发生了一次脱胎换骨的变化,成为了当今最新的一种硬拷贝成像介质.