纳米银粒子对[Ru(bpy)_3]~(2+)光谱学性质的影响及电解质效应

研究了[Ru(bpy)3]2+溶液中引入纳米银粒子的光谱学性质变化规律以及[Ru(bpy)3]2+与纳米银粒子所构成的溶液体系([Ru(bpy)3]2+-Ag)的电解质效应.研究结果表明,[Ru(bpy)3]2+吸附在纳米银粒子表面使纳米银粒子相互桥连形成规则的类链状网络聚集体.纳米银粒子造成[Ru(bpy)3]2+溶液荧光猝灭,且大尺寸的纳米银粒子引起的荧光猝灭程度较大.在[Ru(bpy)3]2+-Ag体系中引入电解质造成纳米银粒子不同程度的聚集和生长.电解质对纳米银聚集影响为:CaCl2MgCl2Ca(NO3)2KClKNO3.随着[Ru(bpy)3]2+-Ag体系中引入电解质含量的增加,溶液的荧光强度先降低而后又逐渐增强,直至达到定值,表明一定量的电解质可产生荧光猝灭释放效应.电解质对荧光强度影响顺序为:Ca(NO3)2CaCl2MgCl2KClKNO3.采用透射电子显微镜、紫外-可见吸收分光光度计和荧光分光光度计等手段从分子间相互作用和能量传输等方面初步探讨了纳米银粒子对表面吸附[Ru(bpy)3]2+溶液光谱学性质的影响机制以及电解质效应.     

Hybrid Silver Nanowire/Titanium Oxides Nanocomposites as Anode for Dye‐Sensitized Solar Cell Application

In this study, we investigated the effect of adding metallic nanowires in the anode of dye‐sensitized solar cell (DSSC) to improve the photovoltaic efficiency. Photo‐excited electrons can be efficiently transferred to the electrode through the network of the dispersed metallic nanowires added in the anode. We compared the photovoltaic performance with the anodes of standard P‐25, the silver nanowire/P‐25, and the TiO₂ coated silver nanowire/P‐25 DSSC. The DSSC with TiO₂ coated silver nanowires shows significantly improved (about 1.5 and 2.0 times) photovoltaic efficiency and structural durability compared with that of the standard P‐25 and the silver nanowires without coating DSSC. The TiO₂ coated silver nanowire can resist the redox chemical corrosions by iodide ions since they are protected from contact with electrolytes during the photovoltaic reaction by the coated thin TiO₂ layer. The presence of the metal network (silver nanowires) improves the production and transportation of light generated current so as to the photovoltaic efficiency.     

Magnetron sputtering of silver nanowires using anodic aluminum oxide template: a new active substrate of surface enhanced Raman scattering and an investigation of its enhanced mechanism

A high quality anodic aluminum oxide (AAO) template with ordered apertures about 50-80 nm was fabricated by anodizing aluminum in electrolytes through a two-step method, and silver nanowires with diameters from 40nm to 70nm were prepared on this AAO template by magnetron sputtering. On the glass covered with silver nanowires, high quality surface enhanced Raman scattering (SERS) spectra of sudan II (C₁₈H₁₆N₂O) with enhancement factors of 10⁵ were obtained. And comparison of SERS spectra on silver nanowires with the SERS spectra of silver colloids indicates that main enhanced mode is lightning rod effect of nanorods on the Sudan II/silver nanowires system.     

湿法电解含金萃取有机相制备金的研究

提出了一种在湿法冶金同时电解载金属有机相制备金属的新方法.并通过电解磷酸三丁酯(TBP)萃取Au(CN)₂^--R₄N⁺的载金有机相制金.考察了电解技术条件、Au浓度、电解质浓度及还原剂等因素对Au回收率的影响.结果表明,此方法不仅可省去冗长的反萃和还原等步骤,而且可以直接以高回收率制备高纯度的金箔;在电解液中加入少量还原剂可明显提高金的回收率.该法也适用于制备银和铜,制备银时所用体系与金相似,但制备铜则在D₂EHPA-正庚烷为载铜有机相及电解质的酸性溶液为水相的体系中进行.     

Determination of thermodynamic properties of silver selenide by the galvanic cell method with solid and liquid electrolytes

The data on the standard thermodynamic functions of silver selenide (naumannite) determined by the EMF method with the electrolyte representing either silver chloride or a glycerol solution of KCl with AgCl are shown. The procedure of measurements with the mentioned electrolytes is developed.     

Tuning the architecture of mesostructures by electrodeposition

When the dimension of materials decreases to mesoscale, their properties can change dramatically, depending on the boundary conditions imposed by the sample architecture including geometry, morphology, and hierarchical structures. Here we show that electrodeposition, a method for reducing materials from a solution onto a substrate, can provide a versatile pathway to tailor the architecture of mesostructures. Novel lead (Pb) structures ranging from nanowires, mesoparticles with octahedral, decahedral, and icosahedral shapes to porous nanowires, multipods, nanobrushes, and even snowflake-shaped structures were synthesized through systematically exploring electrodeposition parameters including reduction potentials, solution concentration, starting materials, supporting electrolytes, and surfactants.     

Room temperature synthesis of silver nanowires from tabular silver bromide crystals in the presence of gelatin

Long silver nanowires were synthesized at room temperature by a simple and fast process derived from the development of photographic films. A film consisting of an emulsion of tabular silver bromide grains in gelatin was treated with a photographic developer (4-(methylamino)phenol sulfate (metol), citric acid) in the presence of additional aqueous silver nitrate. The silver nanowires have lengths of more than 50 μm, some even more than 100 μm, and average diameters of about 80 nm. Approximately, 70% of the metallic silver formed in the reduction consists of silver nanowires. Selected area electron diffraction (SAED) results indicate that the silver nanowires grow along the [111] direction. It was found that the presence of gelatin, tabular silver bromide crystals and silver ions in solution are essential for the formation of the silver nanowires. The nanowires appear to originate from the edges of the silver bromide crystals. They were characterized by transmission electron microscopy (TEM), SAED, scanning electron microscopy (SEM), and powder X-ray diffraction (XRD).     

Polarography in hexamethylphosphoramide: Effect of supporting electrolyte cations

Polarographic reductions of various metal ions such as the silver, cupric, zinc, cobaltous, nickel, ferric, ferrous ions and hydrogen ion in hexamethylphosphoramide (HMPA), have been investigated in the supporting electrolytes with various perchlorates. The reduction of most of these ions is strongly influenced by the cation of the supporting electrolyte. In the presence of the tetraethylammonium ion, when the size of the cation of the supporting electrolyte is small and easily adsorbed on the negatively charged electrode surface, the reductions of metal ions are controlled by some preceding processes and are naturally irreversible. The rate of reduction becomes more rapid with the increase of the size of the cation. Thus, in Hex₄NClO₄ or LiClO solutions, the reduction of these various metal ions takes place almost totally under diffusion control, although the waves of most of metal ions show a maximum. These effects of the cation of the supporting electrolytes on reduction can be explained as a phenomenon occurring on the electrode surface. This phenomenon has been reported in previous papers [1] on the reductions of the alkali and alkaline earth metal ions. The difference in the electrocapillary curves in these solutions is rarely shown at the potential around the electrocapillary maximum, but it is very obviously shown at more negative potential. The difference in the effect of the size of the cation of the supporting electrolyte on reduction of metal ion coincides well with the difference in the electrocapillary curves in these solutions: the effect of the size of the supporting electrolyte cation on the polarographic reduction is rarely shown at the potential around the electrocapillary maximum, but it is very obviously shown at more negative potential; therefore this effect is due to the electrode double-layer difference.     

Determination of electrochemical kinetic parameters by square-wave polarography: Polarographic reduction of Zn(II) in concentrated nitrate and perchlorate supporting electrolyte solutions

The electrochemical kinetic parameters for the polarographic reduction of Zn(II) at a dropping mercury electrode in concentrated supporting electrolytes consisting of sodium, ammonium, lithium, magnesium and calcium nitrates and sodium perchlorate have been determined at 25.0±0.1°C by the square-wave polarographic method. The rate parameter decreased with increase of radius of the alkali-metal cations present in the electrolyte and with increase of charge of the cation of the electrolyte in solution of the same ionic strength. It also decreases, passes through a minimum and then increases with the increase in the concentration of any of the supporting electrolytes. The initial decrease is ascribed to the Frumkin double-layer effect but the latter increase has been explained in terms of the change in the activity of water around the electrode.     

重离子径迹模板法合成银纳米线

聚碳酸脂(PC)膜被高能重离子辐照后沿入射离子路径产生潜径迹, 把带有潜径迹的膜经紫外光敏化后置于NaOH 溶液中进行蚀刻, 通过选择蚀刻条件, 在PC 膜内得到直径从100 到500 nm 导通的核径迹孔. 以带有核径迹孔的PC 膜为模板, 用电化学沉积法制备出不同直径的银纳米线. 在特定的实验条件下(沉积电压25mV、电流密度1-2 mA·cm-2、温度50 益和电解液为0.1 mol·L-1的AgNO3溶液), 获得了沿[111]方向择优取向生长的具有单晶结构的银纳米线. 利用扫描电子显微镜(SEM)、X射线衍射(XRD)、透射电子显微镜(TEM)及选区电子衍射(SAED)等手段对银纳米线的形貌和晶体结构特征进行了表征.     

Kinetics of electropolymerization of 1‐amino‐9,10‐anthraquinone

1‐Amino‐9,10‐anthraquinone was electropolymerized on platinum substrates either from aqueous or nonaqueous electrolytes. The aqueous electrolyte was 6.0 mol L^?1 H₂SO₄, and the nonaqueous solvent was acetonitrile containing lithium perchlorate, LiClO₄, as a supporting electrolyte. The formed polyaminoanthraquinone was stable, and the polymerization process was reproducible. The kinetics of the electropolymerization process was investigated by determining the charge consumed during the electropolymerization as a function of time at different concentrations of the electrolyte components. The results of chronoamperometry have been used to determine the orders of reaction. In either aqueous or nonaqueous solution, the electropolymerization process follows first‐order kinetics with respect to the monomer concentration. In nonaqueous solution, the very small concentrations of water did not affect the order of reaction. The order of reaction with respect to the traces of water and the supporting electrolyte concentration was found to be zero. In aqueous solution, the order of the electropolymerization reaction with respect to the concentration of H₂SO₄ was found to be negative (?0.66), which means that the aqueous electrolyte inhibits the polymerization reaction. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 141–146, 2011     

Controlling synthesis of silver nanowires and dendrites in mixed surfactant solutions

Using a simple wet chemical route, high-yield silver nanowires with an average diameter of 25+/-5 nm and length up to several microm and dendrites with a long central backbone and symmetrically ramified secondary branches have been successfully obtained by reducing AgNO(3) with L-ascorbic acid (AsA) in the mixed surfactant solutions of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). It was found that the architecture of silver nanocrystals was drastically influenced by the concentrations of ascorbic acid. At a given high concentration, a nonequilibrium system was easily built, which favored the formation of fractals. When the concentration was lowered, one-dimensional silver nanowires were successfully obtained. In addition, the presence of electrolyte (NaCl) plays an important role in the preparation of silver nanowires, influencing the silver crystallization process in surprising ways.     

Direct electrosynthesis of Cu,Cd, Zn complexes of piroxicam (4-hydroxy-2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide-1,1,-dioxide) and isoxicam (4-hydroxy-2-methyl-N-(5-methyl-3-isoxazolyl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide) in nonaqueous media by in-situ generation of supporting electrolyte

The direct electrosynthesis of Cu, Cd and Zn complexes of the anti-inflammatory drugs piroxicam (4-hydroxy-2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide-1,1,-dioxide=H-pir) and isoxicam (4-hydroxy-2-methyl-N-(5-methyl-3-isoxazolyl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide=H-isox) was accomplished by electrochemical dissolution of sacrificial metallic anodes in an acetonitrile solution of the ligand. The chemical and electrochemical in-situ generation of supporting electrolyte was used as a means to obtain pure coordination compounds without the use of supporting electrolytes such as tetraalkylammonium or lithium salts in nonaqueous media. Characterization of the complexes obtained by direct synthesis and comparison with those obtained by traditional synthesis shows that a new copper–piroxicam complex was synthesized.     

A Simple Hydrothermal Route to Large‐Scale Synthesis of Uniform Silver Nanowires

This paper describes the preparation of uniform silver nanowires by reducing freshly prepared silver chloride with glucose at 180 °C for 18 hours in the absence of any surfactants or polymers. Scanning electron microscopy studies indicated that the silver nanowires are about 100 nm in diameter and up to 500 μm in length. High‐resolution transmission electron microscopy analyses showed that the silver nanowires grow perpendicularly to the Ag(200) plane. The silver nanowires are believed to grow through a solid–solution–solid process. Some influential factors on the growth of silver nanowires are also discussed.     

Electrocatalytic oxidation of NADH at the self-assembled monolayer of nickel(II) macrocycle on gold electrode

Electroactive self-assembled monolayers (SAMs) of macrocyclic Ni(II) complex (1) were fabricated on gold electrode and its electrochemistry has been studied in different supporting electrolytes. Substantial stabilization of tervalent nickel and a significant negative shift of formal potential of the Ni(3+/2+) couple have been observed when the supporting electrolyte is changed from nitrate to phosphate. Coordination of supporting electrolyte anion with the Ni(III) complex shifts the formal potential and thus tervalent nickel is stabilized. SAM of 1 electrode shows an excellent electrocatalytic activity towards the oxidation of NADH in aqueous NaNO3 solution, whereas it scarcely catalyzes the oxidation of NADH in aqueous phosphate buffer solution. The electrocatalytic oxidation of NADH in Na2SO4 solution is less efficient than that in NaNO3 solution. The anion-dependent electrocatalysis has been discussed on the basis of the difference in the coordinating ability of the anions with the tervalent nickel centers. Steady-state current has been measured for the oxidation of NADH and it was proportional to the concentration of NADH.     

Mixed electrolytes producing very weak electroacoustic signal

The electrokinetic potential of powders dispersed in concentrated solutions of salts can be determined by electroacoustic methods when the ESA (electrokinetic sonic amplitude) signal of electrolyte is properly corrected for. We propose an alternative solution to the problem of electroacoustic measurements at high ionic strengths; that is, the composition of mixed electrolytes with common ions can be adjusted to minimize the ESA signal of the electrolyte. The measurement of electrokinetic potential of powders dispersed in such mixed electrolytes does not require electrolyte background correction. Mixed electrolytes, which produce very weak ESA signals, were prepared from the following salts with common ions: Li+ (LiNO3 + LiCl), Na+ (NaNO3 + NaBr), K+ (KBr + KNO3), and NO(-)3 (LiNO3 + KNO3). Proportions of the components in these mixed electrolytes are concentration dependent. The electrokinetic potentials of alumina in these mixed electrolytes determined with and without background correction were only marginally different.     

Electrochemically initiated polymerization of styrene with tetraalkyl and -aryl group VA halide support electrolytes

The electrochemically initiated polymerization of styrene in methylene chloride solvent with the use of platinum electrodes and tetraalkyl and -aryl group VA halides (i.e., quaternary ammonium, phosphonium, and arsonium compounds) as electrolyte has been investigated. The order of reactivity of the electrolytes with respect to polymerization rate and initiation efficiency was found to be: arsonium > phosphonium > ammonium. Mechanisms involving the electroreduction of the group VA quaternary halides to species capable of electroinitiating polymerization are postulated. The observed losses in solution conductivities during polymerization with the quaternary phosphonium and arsonium electrolytes indicate possible interaction between the initiating radical-ionic species and the supporting electrolyte. In an attempt to further elucidate the mechanism of initiation in these systems, a separate series of experiments, employing the nonpolymerizing monomer, 1,1-diphenylethylene, has been carried out.     

Peculiarities of anodic behavior of gold electrode in thiosulfate electrolytes

Using the methods of quartz microgravimetry and voltammetry, the anodic behavior of gold electrode in thiosulfate electrolytes is studied in the pH range of 7 to 11. It is found that, in the potential range from 0.15 to 1.0 V (NHE), the anodic current is associated predominantly with the oxidation of thiosulfate ions, and the gold dissolution rate in this electrolyte is negligibly low (< 0.02 mA/cm²). It is shown that the study of anodic processes in the neutral thiosulfate electrolytes requires stabilization of solution acidity, because the near-anode layer can be acidified to the pH values, which are sufficient for the formation of elemental sulfur. It is found that the use of Britten-Robinson buffer solution with pH 7 as the supporting electrolyte changes significantly the polarization curve of thiosulfate ion oxidation, but does not raise the gold dissolution rate. An increase in the solution pH to 11 and an exposure of electrode at various potentials (−0.5 and 0.15 V) prior to the onset of potential scanning also do not accelerate considerably the gold dissolution in the thiosulfate electrolyte. A comparison between the regularities of gold anodic behavior in the thiosulfate solutions and earlier studied gold dissolution in the cyanide and thiocarbamide electrolytes showed that they are similar. It is supposed that the specific features of anodic processes in these cases are of a similar nature: the metal dissolution proceeds with the formation of two-ligand complexes with linear structure, which is typical for all aforementioned ligands.     

Synthesis of tubular gold and silver nanoshells using silica nanowire core templates

We report the synthesis of tubular gold and silver nanoshells on silica nanowire core templates in solution. Silica nanowires were synthesized and characterized with optical and NMR methods. Gold nanoparticle seeds (2 to 3 nm) with weak repulsive surfactants such as tetrakis-hydroxymethyl-phosphonium chloride (THPC) were conjugated to the surface of these nanowires. A regrowth process was initiated from these nanoparticles on the surface of the silica nanowires dispersed in gold or silver stock solutions in the presence of reducing agents. Micrometers-long gold and silver tubular nanoshells (80-150 nm o.d.) were made, fully covering the silica nanowires.     

A note on electrolysis with forced convection at large peclet number in a channel and an excess of supporting electrolyte

Electrolysis of an aqueous solution of a metal salt with an excess of supporting electrolyte flowing in a two-dimensional channel is considered. The reaction kinetics is modeled by a Butler-Volmer law. The metal electrodes are symmetrically flush mounted in the channel walls, which are otherwise electrically insulating. Using the perturbation scheme originally proposed by Levich for electrolytes with an excess of supporting electrolyte, a solution in closed form, involving the root of a transcendental algebraic equation, is obtained for the polarization curve. For small and large values of the potential difference between the electrodes, explicit expressions for the polarization curve and the distributions of electric current and concentration on the electrodes are obtained. Particular attention is given to the conditions prevailing during the asymptotic approach to the limiting current. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 4, pp. 508–517. The text was submitted by the authors in English.