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Sample records for roughened silver electrodes

  1. Large-scale controlled fabrication of highly roughened flower-like silver nanostructures in liquid crystalline phase

    PubMed Central

    Yang, Chengliang; Xiang, Xiangjun; Zhang, Ying; Peng, Zenghui; Cao, Zhaoliang; Wang, Junlin; Xuan, Li

    2015-01-01

    Large-scale controllable fabrication of highly roughened flower-like silver nanostructures is demonstrated experimentally via electrodeposition in the liquid crystalline phase. Different sizes of silver flowers are fabricated by adjusting the deposition time and the concentration of the silver nitrate solution. The density of the silver flowers in the sample is also controllable in this work. The flower-like silver nanostructures can serve as effective surface-enhanced Raman scattering and surface-enhanced fluorescence substrates because of their local surface plasmon resonance, and they may have applications in photoluminescence and catalysis. This liquid crystalline phase is used as a soft template for fabricating flower-like silver nanostructures for the first time, and this approach is suitable for large-scale uniform fabrication up to several centimetres. PMID:26216669

  2. Surface-enhanced resonance Raman scattering from methylviologen at a silver electrode: Evidence for two distinct adsorption interactions

    SciTech Connect

    Feng, Qiao; Yue, W.; Cotton, T.M. )

    1990-03-08

    The electronic absorption and resonance Raman spectra of methylviologen radical cation (MV{sup {sm bullet}+}) and fully reduced methylviologen (MV{sup 0}) have been characterized. The enhancement of Raman and resonance Raman (RR) scattering from the dication and its reduction products at polished and roughened silver electrodes was also investigated.

  3. Silver manganese oxide electrodes for lithium batteries

    DOEpatents

    Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

    2006-05-09

    This invention relates to electrodes for non-aqueous lithium cells and batteries with silver manganese oxide positive electrodes, denoted AgxMnOy, in which x and y are such that the manganese ions in the charged or partially charged electrodes cells have an average oxidation state greater than 3.5. The silver manganese oxide electrodes optionally contain silver powder and/or silver foil to assist in current collection at the electrodes and to improve the power capability of the cells or batteries. The invention relates also to a method for preparing AgxMnOy electrodes by decomposition of a permanganate salt, such as AgMnO4, or by the decomposition of KMnO4 or LiMnO4 in the presence of a silver salt.

  4. Surface-enhanced raman scattering from ethylenediaminetetraacetic-disodium salt and nitrate ions on silver electrodes

    NASA Astrophysics Data System (ADS)

    Wetzel, H.; Pettinger, B.; Wenning, U.

    1980-10-01

    Surface-enhanced Raman scattering (SERS) from ethylenediaminetetraacetic-disodium salt adsorbed on silver electrodes has been obtained for the 913, 935 and 1408 cm -1 modes. Addition of this salt to NaNO 3 solutions leads to an enhancement of the NO -3 band at 1050 cm -1. Oxidation/reduction cycles leading to surface roughening and a photochemical reaction caused by the exciting light are prerequisites for these enhancements. The SER signal can irreversibly be quenched by cathodic polarisation.

  5. Failure of silver nanowire transparent electrodes under current flow

    PubMed Central

    2013-01-01

    Silver nanowire transparent electrodes have received much attention as a replacement for indium tin oxide, particularly in organic solar cells. In this paper, we show that when silver nanowire electrodes conduct current at levels encountered in organic solar cells, the electrodes can fail in as little as 2 days. Electrode failure is caused by Joule heating which causes the nanowires to breakup and thus create an electrical discontinuity in the nanowire film. More heat is created, and thus failure occurs sooner, in more resistive electrodes and at higher current densities. Suggestions to improve the stability of silver nanowire electrodes are given. PMID:23680014

  6. Silver-functionalized carbon nanofiber composite electrodes for ibuprofen detection

    NASA Astrophysics Data System (ADS)

    Manea, Florica; Motoc, Sorina; Pop, Aniela; Remes, Adriana; Schoonman, Joop

    2012-06-01

    The aim of this study is to prepare and characterize two types of silver-functionalized carbon nanofiber (CNF) composite electrodes, i.e., silver-decorated CNF-epoxy and silver-modified natural zeolite-CNF-epoxy composite electrodes suitable for ibuprofen detection in aqueous solution. Ag carbon nanotube composite electrode exhibited the best electroanalytical parameters through applying preconcentration/differential-pulsed voltammetry scheme.

  7. Preparation of thin film silver fluoride electrodes from constituent elements

    NASA Technical Reports Server (NTRS)

    Odonnell, P. M.

    1972-01-01

    The feasibility of preparing thin-film metal fluoride electrodes from the elemental constituents has been demonstrated. Silver fluoride cathodes were prepared by deposition of silver on a conducting graphite substrate followed by fluorination under controlled conditions using elemental fluorine. The resulting electrodes were of high purity, and the variables such as size, shape, and thickness were easily controlled.

  8. Life capability of the silver electrode in alkaline electrochemical cells

    NASA Technical Reports Server (NTRS)

    Frank, H. A.

    1976-01-01

    Estimates of silver electrode degradation rates were made by comparing the recently measured capacities with the reported early life capacities. Chemical analyses were carried out to determine the extent of silver loss from the electrode and its distribution throughout the cell components. The results established that the silver electrode is very stable when stored at reduced temperatures in the range of 0 to -51 C, in which it exhibits a permanent degradation in capacity of 0.5%/year. The results also indicated that the silver electrode is not quite as stable when operated and stored at room temperature, where it exhibits permanent degradation in the range of 3% to 14%/year. These results were employed in predicting the life capability of the proposed new Ag-H2 cell and also in assessing the merits of employing silver electrodes in long-life probe batteries.

  9. A nano-silver enzyme electrode for organophosphorus pesticide detection.

    PubMed

    Zheng, Qiqi; Yu, Yonghua; Fan, Kai; Ji, Feng; Wu, Jian; Ying, Yibin

    2016-08-01

    A nano-silver electrode immobilizing acetylcholinesterase (AChE) for the detection of organophosphorus (OPPs) pesticides is reported. Scanning electron microscopy (SEM) was used to characterize the surface structure of two kinds of electrodes fabricated with different sizes of silver powders and the interface between chitosan layer and nano-silver powder layer. Cyclic voltammetry was carried out to characterize the response of silver/chitosan electrode in the absence and in the presence of thiocholine (TCh). It was also used to evaluate the insulativity of the chitosan layer. An amperometric method was performed to measure the response of the electrode to TCh, which is the product of the enzymatic reaction for detecting organophosphorus pesticides indirectly. Although there are many kinds of nanoparticles, silver was chosen for its internal advantage in detecting TCh at low potential without further modification. The result shows nano-silver powder has better performance than usual silver powder, and the limit of detection of paraoxon is 4 ppb under optimized conditions. One percent (w/v) chitosan solution was used as binder for the immobilization of nano-silver powder and AChE, which made it possible for independent electrode fabrication at room temperature, whereas 3% (w/v) chitosan solution was used as insulating compound for controlling the electrode area. Unlike traditional organic insulating ink, chitosan is safe and environmentally friendly, and it is used as insulating material for the first time. The flexible nano-silver/AChE/chitosan electrode was evaluated in Chinese chives and cabbage, and the recoveries of standard addition were 105.11 and 96.41%, respectively. Owing to the antibacterial property of nano-silver and the biocompatibility, safety, and biodegradability of chitosan, the proposed method is safe, facile, environmentally friendly, and has great potential in organophosphorus pesticide detection for food safety. Graphical Abstract Current

  10. A nano-silver enzyme electrode for organophosphorus pesticide detection.

    PubMed

    Zheng, Qiqi; Yu, Yonghua; Fan, Kai; Ji, Feng; Wu, Jian; Ying, Yibin

    2016-08-01

    A nano-silver electrode immobilizing acetylcholinesterase (AChE) for the detection of organophosphorus (OPPs) pesticides is reported. Scanning electron microscopy (SEM) was used to characterize the surface structure of two kinds of electrodes fabricated with different sizes of silver powders and the interface between chitosan layer and nano-silver powder layer. Cyclic voltammetry was carried out to characterize the response of silver/chitosan electrode in the absence and in the presence of thiocholine (TCh). It was also used to evaluate the insulativity of the chitosan layer. An amperometric method was performed to measure the response of the electrode to TCh, which is the product of the enzymatic reaction for detecting organophosphorus pesticides indirectly. Although there are many kinds of nanoparticles, silver was chosen for its internal advantage in detecting TCh at low potential without further modification. The result shows nano-silver powder has better performance than usual silver powder, and the limit of detection of paraoxon is 4 ppb under optimized conditions. One percent (w/v) chitosan solution was used as binder for the immobilization of nano-silver powder and AChE, which made it possible for independent electrode fabrication at room temperature, whereas 3% (w/v) chitosan solution was used as insulating compound for controlling the electrode area. Unlike traditional organic insulating ink, chitosan is safe and environmentally friendly, and it is used as insulating material for the first time. The flexible nano-silver/AChE/chitosan electrode was evaluated in Chinese chives and cabbage, and the recoveries of standard addition were 105.11 and 96.41%, respectively. Owing to the antibacterial property of nano-silver and the biocompatibility, safety, and biodegradability of chitosan, the proposed method is safe, facile, environmentally friendly, and has great potential in organophosphorus pesticide detection for food safety. Graphical Abstract Current

  11. Characterization of hybrid bilayer membranes on silver electrodes as biocompatible SERS substrates to study membrane-protein interactions.

    PubMed

    Millo, Diego; Bonifacio, Alois; Moncelli, Maria Rosa; Sergo, Valter; Gooijer, Cees; van der Zwan, Gert

    2010-11-01

    Hybrid bilayer lipid membranes (HBMs) were built on roughened silver electrodes exhibiting surface-enhanced Raman scattering (SERS) activity. The HBM consisted of a first layer of octadecanethiol (ODT) directly bound to the electrode surface, on which a second layer of 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) was obtained by self-assembled phospholipid vesicle fusion. The electrochemical properties of the HBM were investigated in situ by cyclic voltammetry (CV), AC voltammetry and electrochemical impedance spectroscopy (EIS). The results indicate that our HBMs are well-formed, and their insulating properties are comparable to those observed for HBM supported by smooth metal substrates. The interaction between the bilayer and the human enzyme cytochrome P450 2D6 (CYP2D6) was investigated. Surface-enhanced resonance Raman scattering (SERRS) measurements in combination with AC and EIS, performed on the same electrode sample, proved that the CYP2D6 is immobilized on the HBM without evident alterations of its active site and without significant perturbations of the bilayer architecture. This study yields novel insights into the properties of HBMs built on roughened surfaces, providing in situ electrochemical characterization of a substrate which is suitable for studying peripheral membrane proteins with SERRS spectroscopy.

  12. Highly Robust Silver Nanowire Network for Transparent Electrode.

    PubMed

    Song, Tze-Bin; Rim, You Seung; Liu, Fengmin; Bob, Brion; Ye, Shenglin; Hsieh, Yao-Tsung; Yang, Yang

    2015-11-11

    Solution-processed silver nanowire networks are one of the promising candidates to replace a traditional indium tin oxide as next-generation transparent and flexible electrodes due to their ease of processing, moderate flexibility, high transparency, and low sheet resistance. To date, however, high stability of the nanowire networks remains a major challenge because the long-term usages of these electrodes are limited by their poor thermal and chemical stabilities. Existing methods for addressing this challenge mainly focus on protecting the nanowire network with additional layers that require vacuum processes, which can lead to an increment in manufacturing cost. Here, we report a straightforward strategy of a sol-gel processing as a fast and robust way to improve the stabilities of silver nanowires. Compared with reported nanoparticles embedded in nanowire networks, better thermal and chemical stabilities are achieved via sol-gel coating of TiO2 over the silver nanowire networks. The conformal surface coverage suppressed surface diffusion of silver atoms and prevented chemical corrosion from the environment. These results highlight the important role of the functional layer in providing better thermal and chemical stabilities along with improved electrical properties and mechanical robustness. The silver nanowire/TiO2 composite electrodes were applied as the source and drain electrodes for In2O3 thin-film transistors (TFTs) and the devices exhibited improved electrical performance annealed at 300 °C without the degradation of the electrodes. These key findings not only demonstrated a general and effective method to improve the thermal and chemical stabilities of metal nanowire networks but also provided a basic guideline toward rational design of highly efficient and robust composite electrodes.

  13. Selective growth and integration of silver nanoparticles on silver nanowires at room conditions for transparent nano-network electrode.

    PubMed

    Lu, Haifei; Zhang, Di; Ren, Xingang; Liu, Jian; Choy, Wallace C H

    2014-10-28

    Recently, metal nanowires have received great research interests due to their potential as next-generation flexible transparent electrodes. While great efforts have been devoted to develop enabling nanowire electrodes, reduced contact resistance of the metal nanowires and improved electrical stability under continuous bias operation are key issues for practical applications. Here, we propose and demonstrate an approach through a low-cost, robust, room temperature and room atmosphere process to fabricate a conductive silver nano-network comprising silver nanowires and silver nanoparticles. To be more specific, silver nanoparticles are selectively grown and chemically integrated in situ at the junction where silver nanowires meet. The site-selective growth of silver nanoparticles is achieved by a plasmon-induced chemical reaction using a simple light source at very low optical power density. Compared to silver nanowire electrodes without chemical treatment, we observe tremendous conductivity improvement in our silver nano-networks, while the loss in optical transmission is negligible. Furthermore, the silver nano-networks exhibit superior electrical stability under continuous bias operation compared to silver nanowire electrodes formed by thermal annealing. Interestingly, our silver nano-network is readily peeled off in water, which can be easily transferred to other substrates and devices for versatile applications. We demonstrate the feasibly transferrable silver conductive nano-network as the top electrode in organic solar cells. Consequently, the transparent and conductive silver nano-networks formed by our approach would be an excellent candidate for various applications in optoelectronics and electronics.

  14. Silver-silver sulfate reference electrodes for use in lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Ruetschi, Paul

    Electrochemical properties of silver-silver sulfate reference electrodes for lead-acid batteries are described, and the following possible applications discussed: Determination of individual capacities of positive and negative plates. Monitoring individual electrode behavior during deep discharge and cell reversal. Optimization charge or discharge parameters, by controlling the current such that pre-determined limits of positive or negative half-cell potential are respected. Observation of acid concentration differences, for example due to acid stratification, by measuring diffusion potentials (concentration-cell voltages). Detection of defective cells, and defective plate sets, in a string of cells, at the end of their service life. Silver-silver sulfate reference electrodes, permanently installed in lead-acid cells, may be a means to improve battery management, and therewith to improve reliability and service life. In vented batteries, reference electrodes may be used to limit positive plate polarization during charge, or float-charge. Limiting the positive half-cell potential to an upper, pre-set value would permit to keep anodic corrosion as low as possible. During cycling, discharge could be terminated when the half-cell potential of the positive electrode has dropped to a pre-set limit. This would prevent excessive discharge of the positive electrodes, which could result in an improvement of cycle life. In valve-regulated batteries, reference electrodes may be used to adjust float-charge conditions such as to assure sufficient cathodic polarization of the negative electrodes, in order to avoid sulfation. The use of such reference electrodes could be beneficial particularly in multi-cell batteries, with overall voltages above 12 V, operated in a partial-state-of-charge.

  15. Comparison of the potential dependence of the surface-enhanced raman effect at colloid silver particles and bulk silver electrodes

    NASA Astrophysics Data System (ADS)

    Wetzel, H.; Gerischer, H.; Pettinger, B.

    1982-01-01

    The potential dependence of surface-enhanccd Raman signals from pyridine adsorbed onto silver sol particles is identical to that from pyridine adsorbed on flat silver electrodes. Variation of the potential at the interface silver sol particle/electrolyte was achieved by adding the redox system europiums 3+/europium 2+ and varying the concentration ratio.

  16. Silver corrosion and sulfur detection using a quartz crystal microbalance with silver electrode surfaces

    SciTech Connect

    Zabarnick, S.; Zelesnik, P.; Whitacre, S.D.

    1996-08-01

    A quartz crystal microbalance (QCM) with silver electrodes is used for detection of sulfur and measurement of silver corrosion by sulfur in jet fuels. It is found that the device responds very sensitively to elemental sulfur by reaction at the silver surface, resulting in the formation of surface silver sulfide. It is also expected that the device will respond to hydrogen sulfide. The response of the QCM is found to depend on the fuel matrix. The presence of oxygen inhibits the surface reaction, resulting in a lower mass accumulation. It is also found that the sulfur compounds which produce a response in this test are not players in the formation of autoxidative surface deposition. It is shown that the QCM response (surface mass per unit time) is proportional to the concentration of elemental sulfur present in the fuel.

  17. Inkjet printed fractal-connected electrodes with silver nanoparticle ink.

    PubMed

    Vaseem, Mohammad; Lee, Kil Mok; Hong, A-Ra; Hahn, Yoon-Bong

    2012-06-27

    The development of a simple and reliable method for nanoparticles-based ink in an aqueous solution is still a challenge for its inkjet printing application. Herein, we demonstrate the inkjet printing of fractal-aggregated silver (Ag) electrode lines on substrates. Spherical, monodisperse Ag nanoparticles have been synthesized using silver nitrate as a precursor, ethylene glycol as a reducing agent, and polyvinyl pyrrollidone as a capping agent. As-synthesized pure Ag nanoparticles were well dispersed in water-ethylene glycol mixture, which was directly used as an ink for inkjet printing. Using this ink, the Ag electrodes of fractal-connected lines were printed on Si/SiO2, glass, and polymer substrates. The fractal-connected Ag lines were attributed to the diffusion-limited aggregation of Ag nanoparticles and the effect of annealing on conductivity was also examined. PMID:22670766

  18. Adsorbed States of phosphonate derivatives of N-heterocyclic aromatic compounds, imidazole, thiazole, and pyridine on colloidal silver: comparison with a silver electrode.

    PubMed

    Podstawka, Edyta; Olszewski, Tomasz K; Boduszek, Bogdan; Proniewicz, Leonard M

    2009-09-01

    Here, we report a systematic surface-enhanced Raman spectroscopy (SERS) study of the structures of phosphonate derivatives of the N-heterocyclic aromatic compounds imidazole (ImMeP ([hydroxy(1H-imidazol-5-yl)methyl]phosphonic acid) and (ImMe)(2)P (bis[hydroxy-(1H-imidazol-4-yl)-methyl]phosphinic acid)), thiazole (BAThMeP (butylaminothiazol-2-yl-methyl)phosphonic acid) and BzAThMeP (benzylaminothiazol-2-yl-methyl)phosphonic acid)), and pyridine ((PyMe)(2)P (bis[(hydroxypyridin-3-yl-methyl)]phosphinic acid)) adsorbed on nanometer-sized colloidal particles. We compared these structures to those on a roughened silver electrode surface to determine the relationship between the adsorption strength and the geometry. For example, we showed that all of these biomolecules interact with the colloidal surface through aromatic rings. However, for BzAThMeP, a preferential interaction between the benzene ring and the colloidal silver surface is observed more so than that between the thiazole ring and this substrate. The PC(OH)C fragment does not take part in the adsorption process, and the phosphonate moiety of ImMeP and (ImMe)(2)P, being removed from the surface, only assists in this process.

  19. Surface-enhanced Raman scattering of single-walled carbon nanotubes on modified silver electrode

    NASA Astrophysics Data System (ADS)

    Hou, Xiaomiao; Fang, Yan

    2008-04-01

    A roughed silver electrode modified with gold/silver nanoparticles is used as a substrate, on which high quality SERS of SWCNTs are obtained, indicating that the modified silver electrode is a high-quality SERS-active substrate for SWCNTs. Some new bands that indicate the structure of SWCNTs were obtained. The gold/silver nanoparticles modified on the roughed silver electrode surface can not only make sure the strong adsorption of SWCNTs in this system but also play an important role in magnifying the surface local electric field near the silver electrode surface through resonant surface plasmon excitation. From the rich information on the modified silver electrode obtained from the SERS and the potential dependent SERS, we may deduce the probable SERS mechanism in the process. The theory and experiment results indicate that it is can be used as a new technique for monitoring synthesis quality of SWCNTs. The probable reasons are given.

  20. Silver/silver chloride electrodes for measurement of potential difference in human bronchi

    PubMed Central

    Fajac, I.; Lacronique, J.; Lockhart, A.; Dall'Ava-Santucci, J.; Dusser, D.

    1998-01-01

    BACKGROUND—An easy and reliable method to measure potential difference (PD) in the lower airways would be of interest in the field of cystic fibrosis. We have developed silver/silver chloride (Ag/AgCl) electrodes to measure PD in the lower airways.
METHODS—To validate this technique the nasal PD measured with Ag/AgCl electrodes and with conventional perfused electrodes was compared in 16 patients. The range of PD measured with Ag/AgCl electrodes in the lower airways during fibreoptic bronchoscopy was determined in 14 adult patients and in nine the reproducibility of this technique was examined.
RESULTS—Nasal PD values measured with Ag/AgCl and perfused electrodes were highly correlated (r = 0.985, p<0.0001) and the limits of agreement (mean ±2SD of the difference) between the two methods were -1.91 mV and 1.53 mV. In the lower airways a progressive and slight decrease in PD values with decreasing airway diameter was observed in most patients. The mean (2SD) of the differences between the two tracheal measurements was 0.21 (1.73) mV.
CONCLUSIONS—The use of Ag/AgCl electrodes gives a reliable and reproducible measurement of PD in the lower airways in humans.

 PMID:10193377

  1. Ionic polymer metal composites with polypyrrole-silver electrodes

    NASA Astrophysics Data System (ADS)

    Cellini, F.; Grillo, A.; Porfiri, M.

    2015-03-01

    Ionic polymer metal composites (IPMCs) are a class of soft active materials that are finding increasing application in robotics, environmental sensing, and energy harvesting. In this letter, we demonstrate the fabrication of IPMCs via in-situ photoinduced polymerization of polypyrrole-silver electrodes on an ionomeric membrane. The composition, morphology, and sheet resistance of the electrodes are extensively characterized through a range of experimental techniques. We experimentally investigate IPMC electrochemistry through electrochemical impedance spectroscopy, and we propose a modified Randle's model to interpret the impedance spectrum. Finally, we demonstrate in-air dynamic actuation and sensing and assess IPMC performance against more established fabrication methods. Given the simplicity of the process and the short time required for the formation of the electrodes, we envision the application of our technique in the development of a rapid prototyping technology for IPMCs.

  2. Operando studies of all-vanadium flow batteries: Easy-to-make reference electrode based on silver-silver sulfate

    NASA Astrophysics Data System (ADS)

    Ventosa, Edgar; Skoumal, Marcel; Vázquez, Francisco Javier; Flox, Cristina; Morante, Joan Ramon

    2014-12-01

    In-depth evaluation of the electrochemical performance of all-vanadium redox flow batteries (VRFBs) under operando conditions requires the insertion of a reliable reference electrode in the battery cell. In this work, an easy-to-make reference electrode based on silver-silver sulfate is proposed and described for VRFBs. The relevance and feasibility of the information obtained by inserting the reference electrode is illustrated with the study of ammoxidized graphite felts. In this case, we show that the kinetic of the electrochemical reaction VO2+/VO2+ is slower than that of V2+/V3+ at the electrode. While the slow kinetics at the positive electrode limits the voltage efficiency, the operating potential of the negative electrode, which is outside the stability widow of water, reduces the coulombic efficiency due to the hydrogen evolution.

  3. Modified silver nanowire transparent electrodes with exceptional stability against oxidation.

    PubMed

    Idier, J; Neri, W; Labrugère, C; Ly, I; Poulin, P; Backov, R

    2016-03-11

    We report an easy method to prepare thin, flexible and transparent electrodes that show enhanced inertness toward oxidation using modified silver nanowires (Ag NWs). Stabilization is achieved through the adsorption of triphenylphosphine (PPh3) onto the Ag NW hybrid dispersions prior to their 2D organization as transparent electrodes on polyethylene terephtalate (PET) films. After 110 days in air (20 °C) under atmospheric conditions, the transmittance of the PET/Ag NW/PPh3 based films is nearly unchanged, while the transmittance of the PET/Ag NW-based films decreases by about 5%. The sheet resistance increases for both materials as time elapses, but the rate of increase is more than four times slower for films stabilized by PPh3. The improved transmittance and conductivity results in a significantly enhanced stability for the figure of merit σ dc/σ op. This phenomenon is highlighted in highly oxidative nitric acid vapor. The tested stabilized films in such conditions exhibit a decrease to σ dc/σ op of only 38% after 75 min, whereas conventional materials exhibit a relative loss of 71%. In addition, by contrast to other classes of stabilizers, such as polymer or graphene-based encapsulants, PPh3 does not alter the transparency or conductivity of the modified films. While the present films are made by membrane filtration, the stabilization method could be implemented directly in other liquid processes, including industrially scalable ones. PMID:26866415

  4. Modified silver nanowire transparent electrodes with exceptional stability against oxidation

    NASA Astrophysics Data System (ADS)

    Idier, J.; Neri, W.; Labrugère, C.; Ly, I.; Poulin, P.; Backov, R.

    2016-03-01

    We report an easy method to prepare thin, flexible and transparent electrodes that show enhanced inertness toward oxidation using modified silver nanowires (Ag NWs). Stabilization is achieved through the adsorption of triphenylphosphine (PPh3) onto the Ag NW hybrid dispersions prior to their 2D organization as transparent electrodes on polyethylene terephtalate (PET) films. After 110 days in air (20 °C) under atmospheric conditions, the transmittance of the PET/Ag NW/PPh3 based films is nearly unchanged, while the transmittance of the PET/Ag NW-based films decreases by about 5%. The sheet resistance increases for both materials as time elapses, but the rate of increase is more than four times slower for films stabilized by PPh3. The improved transmittance and conductivity results in a significantly enhanced stability for the figure of merit σ dc/σ op. This phenomenon is highlighted in highly oxidative nitric acid vapor. The tested stabilized films in such conditions exhibit a decrease to σ dc/σ op of only 38% after 75 min, whereas conventional materials exhibit a relative loss of 71%. In addition, by contrast to other classes of stabilizers, such as polymer or graphene-based encapsulants, PPh3 does not alter the transparency or conductivity of the modified films. While the present films are made by membrane filtration, the stabilization method could be implemented directly in other liquid processes, including industrially scalable ones.

  5. Screen printed silver top electrode for efficient inverted organic solar cells

    SciTech Connect

    Kim, Junwoo; Duraisamy, Navaneethan; Lee, Taik-Min; Kim, Inyoung; Choi, Kyung-Hyun

    2015-10-15

    Highlights: • Screen printing of silver pattern. • X-ray diffraction pattern confirmed the face centered cubic structure of silver. • Uniform surface morphology of silver pattern with sheet resistance of 0.06 Ω/sq. • The power conversion efficiency of fabricated solar cell is found to be 2.58%. - Abstract: The present work is mainly focused on replacement of the vacuum process for top electrode fabrication in organic solar cells. Silver top electrode deposited through solution based screen printing on pre-deposited polymeric thin film. The solution based printing technology provides uniform top electrode without damaging the underlying organic layers. The surface crystallinity and surface morphology of silver top electrode are examined through X-ray diffraction, field-emission scanning electron microscope and atomic force microscope. The purity of silver is examined through X-ray energy dispersive spectroscopy. The top electrode exhibits face centered cubic structure with homogeneous morphology. The sheet resistance of top electrode is found to be 0.06 Ω/sq and an average pattern thickness of ∼15 μm. The power conversion efficiency is 2.58%. Our work demonstrates that the solution based screen printing is a significant role in the replacement of vacuum process for the fabrication of top electrode in organic solar cells.

  6. A Comparative Electrochemical Behaviour Study and Analytical Detection of the p-Nitrophenol Using Silver Solid Amalgam, Mercury, and Silver Electrodes

    PubMed Central

    De Souza, Djenaine; Mascaro, Lucia H.; Fatibello-Filho, Orlando

    2011-01-01

    This work reports a comparative electrochemical behaviour study and p-nitrophenol analytical detection using silver solid amalgam, hanging dropping mercury, and silver electrodes. For this, square wave voltammetry was employed, where the analytical responses and the redox mechanisms could be compared for reduction processes of 4-nitrophenol by analysis of the voltammetric responses. The analytical performance of the electrode was evaluated and detection and quantification limits, recovery percentages, repeatability, and reproducibility for the silver solid amalgam and hanging dropping mercury electrodes presented similar values; the results presented for the silver electrode indicated worse analytical parameters than the other electrodes. The results indicate that the silver solid amalgam electrode can be considered a suitable tool and an interesting alternative for the analytical determination of 4-nitrophenol, as well as for the determination of other biological and environmentally interesting compounds that present analytical responses on mercury surfaces. PMID:21647286

  7. Electrochemical reclamation of silver from silver-plating wastewater using static cylinder electrodes and a pulsed electric field.

    PubMed

    Su, Yuan-Bo; Li, Qing-Biao; Wang, Yuan-Peng; Wang, Hai-Tao; Huang, Jia-le; Yang, Xin

    2009-10-30

    Silver was reclaimed from silver-plating wastewater by using a pulsed electric field (PEF) combined with static cylinder electrodes (SCE). The conditions that produced the maximal silver recovery rate (RR(Ag)) (99%) were as follows: average retention time of 10 min, interelectrode gap of 50mm, solution pH of 9.0, temperature of 45 degrees C, initial Ag(I) concentration of 1000 mg L(-1), PEF pulse frequency of 1200 Hz, current density of 5.0 A m(-2) and a pulse duty cycle of 60%. Compared with the conventional direct current (DC) technology, the PEF process exhibited improvements in the silver recovery rate (RR(Ag)), total energy consumption (TEC) and physical properties of the silver deposits, especially for low Ag(I) concentrations, for example, from 500 to 1000 mg L(-1). For an initial Ag(I) concentration of 500 mg L(-1), the PEF process produced an RR(Ag) of up to 99%, and the TEC was 4.56 kWh (kg Ag)(-1). In comparison, the RR(Ag) and TEC were 90% and 5.66 kWh (kg Ag)(-1), respectively, in the DC process. The results of SEM observation and XRD analysis indicated that the silver deposits formed by the PEF process were smaller, denser, and of a higher purity than those produced by the DC process. Therefore, the presented method was effective for reclaiming silver from silver-plating wastewater. PMID:19545945

  8. Highly Conductive, Air-Stable Silver Nanowire@Iongel Composite Films toward Flexible Transparent Electrodes.

    PubMed

    Xiong, Weiwei; Liu, Hongliang; Chen, Yongzhen; Zheng, Meiling; Zhao, Yuanyuan; Kong, Xiangbin; Wang, Ying; Zhang, Xiqi; Kong, Xiangyu; Wang, Pengfei; Jiang, Lei

    2016-09-01

    A new type of flexible transparent electrode is designed, by employing wettability-induced selective electroless-welding of silver nanowire (AgNW) networks, together with a thin conductive iongel as the protective layer. The obtained electrode exhibits high optical transmittance, and excellent air-stability without sacrificing conductivity. PMID:27296551

  9. Further observations of the surface enhanced Raman spectrum of water on silver and copper electrodes

    NASA Astrophysics Data System (ADS)

    Pettinger, B.; Philpott, Michael R.; Gordon, Joseph G.

    1981-04-01

    Two methods useful for detecting surface enhanced Raman (SER) spectra of water on Ag and Cu electrodes are described. The first method uses potential difference spectroscopy to record the SER spectrum of water on a Cu electrode. The second method obtains a SER spectrum of water on an emersed silver electrode. Emersion is a promising technique for reducing the interference from the Raman scattering of bulk water.

  10. Improved thermal oxidation stability of solution-processable silver nanowire transparent electrode by reduced graphene oxide.

    PubMed

    Ahn, Yumi; Jeong, Youngjun; Lee, Youngu

    2012-12-01

    Solution-processable silver nanowire-reduced graphene oxide (AgNW-rGO) hybrid transparent electrode was prepared in order to replace conventional ITO transparent electrode. AgNW-rGO hybrid transparent electrode exhibited high optical transmittance and low sheet resistance, which is comparable to ITO transparent electrode. In addition, it was found that AgNW-rGO hybrid transparent electrode exhibited highly enhanced thermal oxidation and chemical stabilities due to excellent gas-barrier property of rGO passivation layer onto AgNW film. Furthermore, the organic solar cells with AgNW-rGO hybrid transparent electrode showed good photovoltaic behavior as much as solar cells with AgNW transparent electrode. It is expected that AgNW-rGO hybrid transparent electrode can be used as a key component in various optoelectronic application such as display panels, touch screen panels, and solar cells.

  11. Improved thermal oxidation stability of solution-processable silver nanowire transparent electrode by reduced graphene oxide.

    PubMed

    Ahn, Yumi; Jeong, Youngjun; Lee, Youngu

    2012-12-01

    Solution-processable silver nanowire-reduced graphene oxide (AgNW-rGO) hybrid transparent electrode was prepared in order to replace conventional ITO transparent electrode. AgNW-rGO hybrid transparent electrode exhibited high optical transmittance and low sheet resistance, which is comparable to ITO transparent electrode. In addition, it was found that AgNW-rGO hybrid transparent electrode exhibited highly enhanced thermal oxidation and chemical stabilities due to excellent gas-barrier property of rGO passivation layer onto AgNW film. Furthermore, the organic solar cells with AgNW-rGO hybrid transparent electrode showed good photovoltaic behavior as much as solar cells with AgNW transparent electrode. It is expected that AgNW-rGO hybrid transparent electrode can be used as a key component in various optoelectronic application such as display panels, touch screen panels, and solar cells. PMID:23206541

  12. Embroidered Electrode with Silver/Titanium Coating for Long-Term ECG Monitoring

    PubMed Central

    Weder, Markus; Hegemann, Dirk; Amberg, Martin; Hess, Markus; Boesel, Luciano F.; Abächerli, Roger; Meyer, Veronika R.; Rossi, René M.

    2015-01-01

    For the long-time monitoring of electrocardiograms, electrodes must be skin-friendly and non-irritating, but in addition they must deliver leads without artifacts even if the skin is dry and the body is moving. Today's adhesive conducting gel electrodes are not suitable for such applications. We have developed an embroidered textile electrode from polyethylene terephthalate yarn which is plasma-coated with silver for electrical conductivity and with an ultra-thin titanium layer on top for passivation. Two of these electrodes are embedded into a breast belt. They are moisturized with a very low amount of water vapor from an integrated reservoir. The combination of silver, titanium and water vapor results in an excellent electrode chemistry. With this belt the long-time monitoring of electrocardiography (ECG) is possible at rest as well as when the patient is moving. PMID:25599424

  13. [Surface-enhanced Raman spectroscopy of biopolymers: membrane proteins, bacteriorhodopsin and rhodopsin adsorbed on silver electrodes and silver hydrosols].

    PubMed

    Nabiev, I R; Efremov, R G; Chumanov, G D

    1986-01-01

    Surface-enhanced Raman (SER) spectra of purple membranes of Halobacterium halobium and photoreceptor disks of the rod outer segments adsorbed on silver hydrosols were analysed. It has been shown that the intensity of SER spectra of bacterial and visual rhodopsins increases 5 X 10(4) times at adsorption. Concentration relationship of the signal intensity of SER spectra has the maximum at bacteriorhodopsin concentration about 2 X 10(-7) M. It has been shown that adsorption on silver hydrosol leads to fixation of light-induced photochemical transformations in bacterial and visual rhodopsins. Adsorption on the "smooth" electrodes at the potential of the zero charge of silver does not affect the photocycle of bacteriorhodopsin. An increase or decrease of the electrode potential relative to the zero charge point of silver leads to the accumulation of kinetic intermediate K610 and a decrease of the concentration of the form BRh570. It has been shown that on the "smooth" electrode primarily the long-range component of the SER mechanism is realized. Bands corresponding to the vibrations of the atom groups directly contacting with the metal are mainly intensified after redox cycle which increases the concentration of chemosorption centres. A conclusion is drawn that the method of SER spectroscopy of biomolecules adsorbed on "smooth" electrodes, permits obtaining information similar to that obtained from the analysis of Raman spectra of unadsorbed molecules, but at concentrations by two orders less. Adsorption on the electrodes treated with the help of redox cycle permits to obtain highly oriented preparations and to study topography of biopolymers in water solutions and suspensions.

  14. Flow Synthesis of Silver Nanowires for Semitransparent Solar Cell Electrodes: A Life Cycle Perspective.

    PubMed

    Espinosa, Nieves; Søndergaard, Roar R; Jørgensen, Mikkel; Krebs, Frederik C

    2016-04-21

    Silver nanowires (AgNWs) were prepared on a 5 g scale using either the well-known batch synthesis following the polyol method or a new flow synthesis method. The AgNWs were employed as semitransparent electrode materials in organic photovoltaics and compared to traditional printed silver electrodes based on micron sized silver flakes using life cycle analysis and environmental impact analysis methods. The life cycle analysis of AgNWs confirms that they provide an avenue to low-impact semitransparent electrodes. We find that the benefit of AgNWs in terms of embodied energy is less pronounced than generally assumed but that the toxicological and environmental benefits are significant.

  15. Flow Synthesis of Silver Nanowires for Semitransparent Solar Cell Electrodes: A Life Cycle Perspective.

    PubMed

    Espinosa, Nieves; Søndergaard, Roar R; Jørgensen, Mikkel; Krebs, Frederik C

    2016-04-21

    Silver nanowires (AgNWs) were prepared on a 5 g scale using either the well-known batch synthesis following the polyol method or a new flow synthesis method. The AgNWs were employed as semitransparent electrode materials in organic photovoltaics and compared to traditional printed silver electrodes based on micron sized silver flakes using life cycle analysis and environmental impact analysis methods. The life cycle analysis of AgNWs confirms that they provide an avenue to low-impact semitransparent electrodes. We find that the benefit of AgNWs in terms of embodied energy is less pronounced than generally assumed but that the toxicological and environmental benefits are significant. PMID:26969912

  16. Adsorption of acridine on silver electrode: SERS spectra potential dependence as a probe of adsorbate state

    NASA Astrophysics Data System (ADS)

    Solovyeva, Elena V.; Myund, Liubov A.; Dem'yanchuk, Evgeniya M.; Makarov, Artiom A.; Denisova, Anna S.

    2013-02-01

    This work investigates acridine adsorption on the silver electrode surface. The dependence of the acridine SERS spectra on the electrode potential proved to be quite different for azaheterocycle molecules, while the pH effect as expected. The changes in the acridine SERS spectrum caused by the double electric layer (DEL) rearrangement can be explained by sorption/desorption rather than the adsorbate molecule reorientation. The presence of chloride anions close to the silver surface is important not only for the SERS-active properties but for the formation of the stabilised surface complexes of the protonated acridine as well.

  17. Laser-Direct Writing of Silver Metal Electrodes on Transparent Flexible Substrates with High-Bonding Strength.

    PubMed

    Zhou, Weiping; Bai, Shi; Ma, Ying; Ma, Delong; Hou, Tingxiu; Shi, Xiaomin; Hu, Anming

    2016-09-21

    We demonstrate a novel approach to rapidly fabricate conductive silver electrodes on transparent flexible substrates with high-bonding strength by laser-direct writing. A new type of silver ink composed of silver nitrate, sodium citrate, and polyvinylpyrrolidone (PVP) was prepared in this work. The role of PVP was elucidated for improving the quality of silver electrodes. Silver nanoparticles and sintered microstructures were simultaneously synthesized and patterned on a substrate using a focused 405 nm continuous wave laser. The writing was completed through the transparent flexible substrate with a programmed 2D scanning sample stage. Silver electrodes fabricated by this approach exhibit a remarkable bonding strength, which can withstand an adhesive tape test at least 50 times. After a 1500 time bending test, the resistance only increased 5.2%. With laser-induced in-situ synthesis, sintering, and simultaneous patterning of silver nanoparticles, this technology is promising for the facile fabrication of conducting electronic devices on flexible substrates. PMID:27560607

  18. Effect of fractal silver electrodes on charge collection and light distribution in semiconducting organic polymer films

    SciTech Connect

    Chamousis, RL; Chang, LL; Watterson, WJ; Montgomery, RD; Taylor, RP; Moule, AJ; Shaheen, SE; Ilan, B; van de Lagemaat, J; Osterloh, FE

    2014-08-21

    Living organisms use fractal structures to optimize material and energy transport across regions of differing size scales. Here we test the effect of fractal silver electrodes on light distribution and charge collection in organic semiconducting polymer films made of P3HT and PCBM. The semiconducting polymers were deposited onto electrochemically grown fractal silver structures (5000 nm x 500 nm; fractal dimension of 1.71) with PEDOT:PSS as hole-selective interlayer. The fractal silver electrodes appear black due to increased horizontal light scattering, which is shown to improve light absorption in the polymer. According to surface photovoltage spectroscopy, fractal silver electrodes outperform the flat electrodes when the BHJ film thickness is large (>400 nm, 0.4 V photovoltage). Photocurrents of up to 200 microamperes cm(-2) are generated from the bulk heterojunction (BHJ) photoelectrodes under 435 nm LED (10-20 mW cm(-2)) illumination in acetonitrile solution containing 0.005 M ferrocenium hexafluorophosphate as the electron acceptor. The low IPCE values (0.3-0.7%) are due to slow electron transfer to ferrocenium ion and due to shunting along the large metal-polymer interface. Overall, this work provides an initial assessment of the potential of fractal electrodes for organic photovoltaic cells.

  19. Anodic stripping voltammetry with graphite felt electrodes for the trace analysis of silver.

    PubMed

    Davies, Trevor J

    2016-08-01

    Graphite felt (GF) is a mass produced porous carbon electrode material commonly used in redox flow batteries. Previous studies have suggested GF may have valuable applications in electroanalysis as a low cost disposable carbon electrode material, although most GF sensors have used flow cell arrangements. In this work, an elegant wetting technique is employed that allows GF electrodes to be used in quiescent solution to detect trace levels of silver in water via anodic stripping voltammetry. GF electrodes display good repeatability and a limit of detection of 25 nM of Ag(+) in 0.1 M HNO3, with a linear range spanning two orders of magnitude. This compares to a value of around 140 nM when using conventional carbon electrodes. Combined with their low cost and disposable nature, the results suggest GF electrodes can make a valuable contribution to electroanalysis. PMID:27276994

  20. Direct inkjet printing of micro-scale silver electrodes on polydimethylsiloxane (PDMS) microchip

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Ren, X.; Kim, J. W.; Noh, H.

    2014-11-01

    Recently, direct inkjet printing of conductive solutions has received much attention in the microfluidics and lab-on-a-chip community because of its low-cost and mask-free deposition of electrodes on various substrates. However, the investigation of micro-scale direct inkjet printing on the polydimethylsiloxane (PDMS) substrate has not been completed. Here we present a direct inkjet printing technique to produce narrow (40-90 µm) silver microelectrodes on PDMS. Extensive experimental characterization studies on the pattern uniformity and electrical properties of the printed silver lines are presented. The effect of major printing parameters such as drop spacing, sintering temperature and duration, platen temperature, and nozzle temperature have been thoroughly investigated. We also investigated multiple layer printing as well as the effects of thermal expansion and mechanical bending. In order to demonstrate the utility of the inkjet-printed silver microelectrode, we fabricated both quadruple and castellated electrodes, and conducted dielectrophoretic manipulation of microbeads. The results clearly show that the printed silver electrodes can be used for electrokinetic applications in PDMS microchip devices. We believe that the direct inkjet printing of silver ink on PDMS presented here can provide a very convenient way of creating microelectrodes on PDMS devices for a variety of applications in the MEMS, microfluidics, and lab-on-a-chip communities.

  1. Laser Processed Silver Nanowire Network Transparent Electrodes for Novel Electronic Devices

    NASA Astrophysics Data System (ADS)

    Spechler, Joshua Allen

    Silver nanowire network transparent conducting layers are poised to make headway into a space previously dominated by transparent conducting oxides due to the promise of a flexible, scaleable, lab-atmosphere processable alternative. However, there are many challenges standing in the way between research scale use and consumer technology scale adaptation of this technology. In this thesis we will explore many, and overcome a few of these challenges. We will address the poor conductivity at the narrow nanowire-nanowire junction points in the network by developing a laser based process to weld nanowires together on a microscopic scale. We address the need for a comparative metric for transparent conductors in general, by taking a device level rather than a component level view of these layers. We also address the mechanical, physical, and thermal limitations to the silver nanowire networks by making composites from materials including a colorless polyimide and titania sol-gel. Additionally, we verify our findings by integrating these processes into devices. Studying a hybrid organic/inorganic heterojunction photovoltaic device we show the benefits of a laser processed electrode. Green phosphorescent organic light emitting diodes fabricated on a solution phase processed silver nanowire based electrode show favorable device metrics compared to a conductive oxide electrode based control. The work in this thesis is intended to push the adoption of silver nanowire networks to further allow new device architectures, and thereby new device applications.

  2. Surface-enhanced Raman scattering studies on the interaction of phosphonate derivatives of imidazole, thiazole, and pyridine with a silver electrode in aqueous solution.

    PubMed

    Podstawka, Edyta; Kudelski, Andrzej; Olszewski, Tomasz K; Boduszek, Bogdan

    2009-07-23

    Surface-enhanced Raman scattering (SERS) spectra from phosphonate derivatives of N-heterocyclic aromatic compounds immobilized on an electrochemically roughened silver electrode surface are reported and compared to Raman spectra of the corresponding solid species. The tested compounds contain imidazole [ImMeP ([hydroxy-(1H-imidazol-5-yl)-methyl]-phosphonic acid) and (ImMe)2P (bis[hydroxy-(1H-imidazol-4-yl)-methyl]-phosphinic acid)]; thiazole [BAThMeP ((butylamino-thiazol-2-yl-methyl)-phosphonic acid) and BzAThMeP ((benzylamino-thiazol-2-yl-methyl)-phosphonic acid)]; and pyridine ((PyMe)2P (bis[(hydroxy-pyridin-3-yl-methyl)]-phosphinic acid) aromatic rings. Changes in wavenumber, broadness, and the enhancement of N-heterocyclic aromatic ring bands upon adsorption are consistent with the adsorption primarily occurring through the N lone pair of electrons with the ring arranged in a largely edge-on manner for ImMeP and BzAThMeP or in a slightly inclined orientation to the silver electrode surface at an intermediate angle from the surface normal for (ImMe)2P, BAThMeP, and (PyMe)2P. A strong enhancement of a roughly 1500 cm(-1) SERS signal for ImMeP and (PyMe)2P is also observed. This phenomenon is attributed to the formation of a localized C=C bond, which is accompanied by a decrease in the ring-surface pi-electrons' overlap. In addition, more intense SERS bands due to the benzene ring in BzAThMeP are observed than those observed for the thiazole ring, which suggests a preferential adsorption of benzene. Some interaction of a phosphonate unit is also suggested but with moderate strength between biomolecules. The strength of the P=O coordination to the silver electrode is highest for ImMeP but lowest for BzAThMeP. For all studied biomolecules, the contribution of the structural components to their ability to interact with their receptors was correlated with the SERS patterns.

  3. Embedded silver PDMS electrodes for single cell electrical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Wei, Yuan; Xu, Zhensong; Cachia, Mark A.; Nguyen, John; Zheng, Yi; Wang, Chen; Sun, Yu

    2016-09-01

    This paper presents a microfluidic device with wide channels and embedded AgPDMS electrodes for measuring the electrical properties of single cells. The work demonstrates the feasibility of using a large channel design and embedded electrodes for impedance spectroscopy to circumvent issues such as channel clogging and limited device re-usability. AgPDMS electrodes were formed on channel sidewalls for impedance detection and cell electrical properties measurement. Equivalent circuit models were used to interpret multi-frequency impedance data to quantify each cell’s cytoplasm conductivity and specific membrane capacitance. T24 cells were tested to validate the microfluidic system and modeling results. Comparisons were then made by measuring two leukemia cell lines (AML-2 and HL-60) which were found to have different cytoplasm conductivity values (0.29  ±  0.15 S m-1 versus 0.47  ±  0.20 S m-1) and specific membrane capacitance values (41  ±  25 mF m-2 versus 55  ±  26 mF m-2) when the cells were flown through the wide channel and measured by the AgPDMS electrodes.

  4. Embedded silver PDMS electrodes for single cell electrical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Wei, Yuan; Xu, Zhensong; Cachia, Mark A.; Nguyen, John; Zheng, Yi; Wang, Chen; Sun, Yu

    2016-09-01

    This paper presents a microfluidic device with wide channels and embedded AgPDMS electrodes for measuring the electrical properties of single cells. The work demonstrates the feasibility of using a large channel design and embedded electrodes for impedance spectroscopy to circumvent issues such as channel clogging and limited device re-usability. AgPDMS electrodes were formed on channel sidewalls for impedance detection and cell electrical properties measurement. Equivalent circuit models were used to interpret multi-frequency impedance data to quantify each cell’s cytoplasm conductivity and specific membrane capacitance. T24 cells were tested to validate the microfluidic system and modeling results. Comparisons were then made by measuring two leukemia cell lines (AML-2 and HL-60) which were found to have different cytoplasm conductivity values (0.29  ±  0.15 S m‑1 versus 0.47  ±  0.20 S m‑1) and specific membrane capacitance values (41  ±  25 mF m‑2 versus 55  ±  26 mF m‑2) when the cells were flown through the wide channel and measured by the AgPDMS electrodes.

  5. Planar silver nanowire, carbon nanotube and PEDOT:PSS nanocomposite transparent electrodes

    NASA Astrophysics Data System (ADS)

    Stapleton, Andrew J.; Yambem, Soniya D.; Johns, Ashley H.; Afre, Rakesh A.; Ellis, Amanda V.; Shapter, Joe G.; Andersson, Gunther G.; Quinton, Jamie S.; Burn, Paul L.; Meredith, Paul; Lewis, David A.

    2015-04-01

    Highly conductive, transparent and flexible planar electrodes were fabricated using interwoven silver nanowires and single-walled carbon nanotubes (AgNW:SWCNT) in a PEDOT:PSS matrix via an epoxy transfer method from a silicon template. The planar electrodes achieved a sheet resistance of 6.6 ± 0.0 Ω/□ and an average transmission of 86% between 400 and 800 nm. A high figure of merit of 367 Ω-1 is reported for the electrodes, which is much higher than that measured for indium tin oxide and reported for other AgNW composites. The AgNW:SWCNT:PEDOT:PSS electrode was used to fabricate low temperature (annealing free) devices demonstrating their potential to function with a range of organic semiconducting polymer:fullerene bulk heterojunction blend systems.

  6. Electro-active Polymer Actuator Based on Sulfonated Polyimide with Highly Conductive Silver Electrodes Via Self-metallization.

    PubMed

    Song, Jiangxuan; Jeon, Jin-Han; Oh, Il-Kwon; Park, K C

    2011-10-01

    We report here a facile synthesis of high performance electro-active polymer actuator based on a sulfonated polyimide with well-defined silver electrodes via self-metallization. The proposed method greatly reduces fabrication time and cost, and obviates a cation exchange process required in the fabrication of ionic polymer-metal composite actuators. Also, the self-metallized silver electrodes exhibit outstanding metal-polymer adhesion with high conductivity, resulting in substantially larger tip displacements compared with Nafion-based actuators.

  7. Large Pulsed Electron Beam Welded Percolation Networks of Silver Nanowires for Transparent and Flexible Electrodes.

    PubMed

    Kim, Jisoo; Nam, Yun Seok; Song, Myoung Hoon; Park, Hyung Wook

    2016-08-17

    Mechanical properties of transparent electrodes, including flexibility, are important in flexible electronics for sustaining electrical conductivity under bending with small radius of curvature. Low contact resistance of junctions in metal nanowire percolation networks is the most important factor to produce electrodes with excellent optical, electrical and mechanical performance. Here, we report the fabrication of welded silver nanowire percolation networks using large pulsed electron beam (LPEB) irradiation as a welding process of silver nanowires (AgNWs). It results in modification of electrical and mechanical properties because of the low contact resistance at welded junctions. Consequently, the flexible and transparent AgNW electrodes fabricated by LPEB irradiation showed lower sheet resistance of 12.63 Ω sq(-1) at high transmittance of 93% (at 550 nm), and superb mechanical flexibility, compared with other AgNW electrodes prepared by thermal treatement and without any treatment. Polymer light-emitting diodes (PLEDs) using AgNWs by LPEB irradiation were fabricated to confirm that the AgNW electrode by LPEB irradiation was able to become alternative to indium tin oxide (ITO) and they showed good device performance as a maximum luminous efficiency of 7.37 cd A(-1), and excellent mechanical flexibility under bending with small radius of curvature. PMID:27463783

  8. Large Pulsed Electron Beam Welded Percolation Networks of Silver Nanowires for Transparent and Flexible Electrodes.

    PubMed

    Kim, Jisoo; Nam, Yun Seok; Song, Myoung Hoon; Park, Hyung Wook

    2016-08-17

    Mechanical properties of transparent electrodes, including flexibility, are important in flexible electronics for sustaining electrical conductivity under bending with small radius of curvature. Low contact resistance of junctions in metal nanowire percolation networks is the most important factor to produce electrodes with excellent optical, electrical and mechanical performance. Here, we report the fabrication of welded silver nanowire percolation networks using large pulsed electron beam (LPEB) irradiation as a welding process of silver nanowires (AgNWs). It results in modification of electrical and mechanical properties because of the low contact resistance at welded junctions. Consequently, the flexible and transparent AgNW electrodes fabricated by LPEB irradiation showed lower sheet resistance of 12.63 Ω sq(-1) at high transmittance of 93% (at 550 nm), and superb mechanical flexibility, compared with other AgNW electrodes prepared by thermal treatement and without any treatment. Polymer light-emitting diodes (PLEDs) using AgNWs by LPEB irradiation were fabricated to confirm that the AgNW electrode by LPEB irradiation was able to become alternative to indium tin oxide (ITO) and they showed good device performance as a maximum luminous efficiency of 7.37 cd A(-1), and excellent mechanical flexibility under bending with small radius of curvature.

  9. Surface enhanced Raman scattering of new acridine based fluorophore adsorbed on silver electrode.

    PubMed

    Solovyeva, Elena V; Myund, Liubov A; Denisova, Anna S

    2015-10-01

    4,5-Bis(N,N-di(2-hydroxyethyl)iminomethyl)acridine (BHIA) is a new acridine based fluoroionophore and a highly-selective sensor for cadmium ion. The direct interaction of the aromatic nitrogen atom with a surface is impossible since there are bulky substituents in the 4,5-positions of the acridine fragment. Nevertheless BHIA molecule shows a reliable SERS spectrum while adsorbed on a silver electrode. The analysis of SERS spectra pH dependence reveals that BHIA species adsorbed on a surface can exist in both non-protonated and protonated forms. The adsorption of BHIA from alkaline solution is accompanied by carbonaceous species formation at the surface. The intensity of such "carbon bands" turned out to be related with the supporting electrolyte (KCl) concentration. Upon lowering the electrode potential the SERS spectra of BHIA do not undergo changes but the intensity of bands decreases. This indicates that the adsorption mechanism on the silver surface is realized via aromatic system of acridine fragment. In case of such an adsorption mechanism the chelate fragment of the BHIA molecule is capable of interaction with the solution components. Addition of Cd(2+) ions to a system containing BHIA adsorbed on a silver electrode in equilibrium with the solution leads to the formation of BHIA/Cd(2+) complex which desorption causes the loss of SERS signal. PMID:25956332

  10. Silver nanowire/polyaniline composite transparent electrode with improved surface properties

    SciTech Connect

    Kumar, A.B.V. Kiran; Jiang, Jianwei; Bae, Chang Wan; Seo, Dong Min; Piao, Longhai Kim, Sang-Ho

    2014-09-15

    Highlights: • AgNWs/PANI transparent electrode was prepared by layer-by-layer coating method. • The surface roughness of the electrode reached to 6.5 nm (root mean square). • The electrode had reasonable sheet resistance (25 Ω/□) and transmittance (83.5%). - Abstract: Silver nanowires (AgNWs) are as potential candidates to replace indium tin oxide (ITO) in transparent electrodes because of their preferred conducting and optical properties. However, their rough surface properties are not favorable for the fabrication of optoelectronic devices, such as displays and thin-film solar cells. In the present investigation, AgNWs/polyaniline composite transparent electrodes with better surface properties were successfully prepared. AgNWs were incorporated into polyaniline:polystyrene sulfonate (PANI:PSS) by layer-by-layer coating and mechanical pressing. PANI:PSS decreased the surface roughness of the AgNWs electrode by filling the gap of the random AgNWs network. The transparent composite electrode had decreased surface roughness (root mean square 6.5 nm) with reasonable sheet resistance (25 Ω/□) and transmittance (83.5%)

  11. Uniformly embedded silver nanomesh as highly bendable transparent conducting electrode

    NASA Astrophysics Data System (ADS)

    Choi, Hak-Jong; Choo, Soyoung; Jung, Pil-Hoon; Shin, Ju-Hyeon; Kim, Yang-Doo; Lee, Heon

    2015-02-01

    Ag-nanomesh-based highly bendable conducting electrodes are developed using a combination of metal nanotransfer printing and embossing for the 6-inch wafer scale. Two Ag nanomeshes, including pitch sizes of 7.5 and 10 μm, are used to obtain highly transparent (approximately 85% transmittance at a wavelength of 550 nm) and electrically conducting properties (below 10 Ω sq-1). The Ag nanomeshes are also distinguished according to the fabrication process, which is called transferred or embedded Ag nanomesh on polyethylene terephthalate (PET) substrate, in order to compare their stability against bending stress. Then the enhancement of bending stability when the Ag nanomesh is embedded in the PET substrate is confirmed.

  12. Determination of serotonin on platinum electrode modified with carbon nanotubes/polypyrrole/silver nanoparticles nanohybrid.

    PubMed

    Cesarino, Ivana; Galesco, Heloisa V; Machado, Sergio A S

    2014-07-01

    A new sensor has been developed by a simple electrodeposition of multi-walled carbon nanotubes (MWCNT), polypyrrole (PPy) and colloidal silver nanoparticles on the platinum (Pt) electrode surface. The Pt/MWCNT/PPy/AgNPs electrode was applied to the detection of serotonin in plasmatic serum samples using differential pulse voltammetry (DPV). The synergistic effect of MWCNT/PPy/AgNPs nanohybrid formed yielded a LOD of 0.15 μmol L(-1) (26.4 μg L(-1)). Reproducibility and repeatability values of 2.2% and 1.7%, respectively, were obtained compared to the conventional procedure. The proposed electrode can be an effective material to be used in biological analysis.

  13. Flexible, silver nanowire network nickel hydroxide core-shell electrodes for supercapacitors

    NASA Astrophysics Data System (ADS)

    Yuksel, Recep; Coskun, Sahin; Kalay, Yunus Eren; Unalan, Husnu Emrah

    2016-10-01

    We present a novel one-dimensional coaxial architecture composed of silver nanowire (Ag NW) network core and nickel hydroxide (Ni(OH)2) shell for the realization of coaxial nanocomposite electrode materials for supercapacitors. Ag NWs are formed conductive networks via spray coating onto polyethylene terephthalate (PET) substrates and Ni(OH)2 is gradually electrodeposited onto the Ag NW network to fabricate core-shell electrodes for supercapacitors. Synergy of highly conductive Ag NWs and high capacitive Ni(OH)2 facilitate ion and electron transport, enhance electrochemical properties and result in a specific capacitance of 1165.2 F g-1 at a current density of 3 A g-1. After 3000 cycles, fabricated nanocomposite electrodes show 93% capacity retention. The rational design explored in this study points out the potential of nanowire based coaxial energy storage devices.

  14. UV/Vis Spectroelectrochemistry as a Tool for Monitoring the Fabrication of Sensors Based on Silver Nanoparticle Modified Electrodes

    PubMed Central

    Fernández-Blanco, Cristina; Colina, Álvaro; Heras, Aránzazu

    2013-01-01

    A new controlled current multipulse methodology has been developed to modify the screen-printed electrode surface with silver nanoparticles (AgNPs). Spectroelectrochemistry has provided not only information about the type of nanoparticles (NPs) deposited on the electrode surface, but also about the electrosynthesis process. Small NPs without plasmon band are initially generated. Next, these nuclei grow to form bigger NPs in the reduction pulses with a characteristic plasmon band centered at 400 nm. Most of the NPs are generated during the first reduction pulses and a linear growth of the absorbance at a lower reaction rate was obtained in the subsequent pulses. Oxidation pulses do not redissolve completely silver NPs but only partially, meaning that very stable NPs are generated. AgNPs-modified electrodes have been successfully used to determine hydrogen peroxide. Spectroelectrochemistry has also yielded very useful information to understand the voltammetric signal obtained during the reduction of H2O2 on silver modified electrodes. PMID:23645107

  15. Silver nanoparticle-modified electrode for the determination of nitro compound-containing pesticides.

    PubMed

    de Lima, Camila Alves; Santana, Edson Roberto; Piovesan, Jamille Valéria; Spinelli, Almir

    2016-04-01

    This paper reports the electroanalytical determination of pendimethalin and ethyl parathion by square-wave adsorptive stripping voltammetry using a material comprised of chitosan-stabilized silver nanoparticles to modify a glassy carbon electrode. Under optimized experimental conditions, the peak current was found to vary linearly with the concentration of pendimethalin in the range of 70 to 2000 nmol L(-1) and with concentration of ethyl parathion in the range of 40 to 8000 nmol L(-1). Detection limits of 36 and 40 nmol L(-1) were obtained for pendimethalin and ethyl parathion, respectively. The silver - nanoparticle-modified electrode was successfully employed for the analysis of pesticides in tap and mineral water (pendimethalin) and in lettuce and honey (ethyl parathion) samples. Pendimethalin recovery was between 94 and 100 %, and ethyl parathion recovery was between 97 and 101 %, indicating no significant matrix interference effects on the analytical results. The accuracy of the electroanalytical methodology using the proposed modified electrode was also compared to that of the UV-vis spectrophotometric method. PMID:26873207

  16. Tailored silver grid as transparent electrodes directly written by femtosecond laser

    NASA Astrophysics Data System (ADS)

    Zhao, Yuan-Yuan; Zheng, Mei-Ling; Dong, Xian-Zi; Jin, Feng; Liu, Jie; Ren, Xue-Liang; Duan, Xuan-Ming; Zhao, Zhen-Sheng

    2016-05-01

    We present the design and realization of silver grid transparent electrodes (SGTEs) easily fabricated by femtosecond laser direct writing of silver aqueous solution. The fabricated SGTEs with a sheet resistance down to 47 Ω/□ and optical transmittance up to 93% are demonstrated. These sheet resistance and transmittance values are comparable to commercially available indium tin oxide. High uniform morphology of the directly written SGTEs results in the ultra-stable tailored performance parameter at electronic and optical fields. The sheet resistance and transmittance can be tailored precisely by manipulating the filling fraction of the uniform SGTEs. This study provides an approach for creating SGTEs in a controllable fashion, and the SGTEs exhibit high transmittance and low sheet resistance, which could open up new avenues towards widespread application in electronics, photovoltaics, and optoelectronics.

  17. Inkjet printed silver nanowire network as top electrode for semi-transparent organic photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Lu, Hui; Lin, Jian; Wu, Na; Nie, Shuhong; Luo, Qun; Ma, Chang-Qi; Cui, Zheng

    2015-03-01

    A method for direct inkjet printing of silver nanowire (Ag NW) to form transparent conductive network as the top electrode for inverted semi-transparent organic photovoltaic devices (OPV) was developed. The highest power conversion efficiency of the poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PC61BM) based OPV was achieved to be 2.71% when the top electrode was formed by 7 times of printing. In general, devices with printed Ag NW top electrode had similar open-circuit voltage (VOC, around 0.60 V) but lower fill factor (FF, 0.33-0.54) than that of device with thermally deposited Ag opaque electrode (reference device). Both FF and short-circuit current density (JSC), however, were found to be increasing with the increase of printing times (3, 5, and 7), which could be partially attributed to the improved conductivity of Ag NW network electrodes. The solvent effect on device performances was studied carefully by comparing the current density-voltage (J-V) curves of different devices. The results revealed that solvent treatment on the anode buffer layer during printing led to a decrease of charge injection selectivity and an increase of charge recombination at the anode interface, which was considered to be the reason for the degrading of device performance.

  18. Autocatalysis by the intermediate surface hydroxide formed during hydrogen peroxide reduction on silver electrodes

    NASA Astrophysics Data System (ADS)

    Doblhofer, K.; Flätgen, G.; Horswell, S.; Pettinger, B.; Wasle, S.; Weil, K. G.

    2009-06-01

    Recent electrochemical studies of the cathodic reduction of hydrogen peroxide (H 2O 2) on silver electrodes in acidic electrolyte (HClO 4) revealed a novel autocatalytic reaction path. Adsorbed hydroxyl groups, OH ad, were proposed to act as the catalyst. To gather further clarity about this mechanism, in particular about the presence and nature of the postulated adsorbate OH ad, in the present work surface science experiments on Ag(1 1 1) electrodes are evaluated. It is concluded that the species OH ad is identical with the surface AgOH formed in alkaline solution as a relatively stable intermediate in the anodic oxidation of OH - to surface-Ag 2O.

  19. The second-harmonic response of single-crystal silver electrodes obtained with an interference method

    NASA Astrophysics Data System (ADS)

    Beltramo, G.; Bilger, C.; Pettinger, B.; Schmickler, W.

    1998-12-01

    The second-harmonic response of several single-crystal silver electrodes is investigated at a long wavelength. In contrast to earlier experiments, the phase of the signal is obtained directly by an interference method. By comparing measurements at two different angles of incidence, the Rudnick-Stern coefficient characterizing the response perpendicular to the surface can be estimated; for Ag(100) and Ag(111) it agrees fairly well with calculations based on the jellium model. For the Ag(110) surface, the twofold amplitude depends on the electrode potential; in addition, a contribution with a three-fold symmetry is observed. These unexpected features are probably caused by a facetting of the Ag(110) surface.

  20. Silver Nanowire Top Electrodes in Flexible Perovskite Solar Cells using Titanium Metal as Substrate.

    PubMed

    Lee, Minoh; Ko, Yohan; Min, Byoung Koun; Jun, Yongseok

    2016-01-01

    Flexible perovskite solar cells (FPSCs) have various applications such as wearable electronic textiles and portable devices. In this work, we demonstrate FPSCs on a titanium metal substrate employing solution-processed silver nanowires (Ag NWs) as the top electrode. The Ag NW electrodes were deposited on top of the spiro-MeOTAD hole transport layer by a carefully controlled spray-coating method at moderate temperatures. The power conversion efficiency (PCE) reached 7.45 % under AM 1.5 100 mW cm(-2) illumination. Moreover, the efficiency for titanium-based FPSCs decreased only slightly (by 2.6 % of the initial value) after the devices were bent 100 times. With this and other advances, fully solution-based indium-free flexible photovoltaics, advantageous in terms of price and processing, have the potential to be scaled into commercial production. PMID:26612081

  1. Silver Nanowire Top Electrodes in Flexible Perovskite Solar Cells using Titanium Metal as Substrate.

    PubMed

    Lee, Minoh; Ko, Yohan; Min, Byoung Koun; Jun, Yongseok

    2016-01-01

    Flexible perovskite solar cells (FPSCs) have various applications such as wearable electronic textiles and portable devices. In this work, we demonstrate FPSCs on a titanium metal substrate employing solution-processed silver nanowires (Ag NWs) as the top electrode. The Ag NW electrodes were deposited on top of the spiro-MeOTAD hole transport layer by a carefully controlled spray-coating method at moderate temperatures. The power conversion efficiency (PCE) reached 7.45 % under AM 1.5 100 mW cm(-2) illumination. Moreover, the efficiency for titanium-based FPSCs decreased only slightly (by 2.6 % of the initial value) after the devices were bent 100 times. With this and other advances, fully solution-based indium-free flexible photovoltaics, advantageous in terms of price and processing, have the potential to be scaled into commercial production.

  2. Improved efficiency of hybrid organic photovoltaics by pulsed laser sintering of silver nanowire network transparent electrode.

    PubMed

    Spechler, Joshua A; Nagamatsu, Ken A; Sturm, James C; Arnold, Craig B

    2015-05-20

    In this Research Article, we demonstrate pulsed laser processing of a silver nanowire network transparent conductor on top of an otherwise complete solar cell. The macroscopic pulsed laser irradiation serves to sinter nanowire-nanowire junctions on the nanoscale, leading to a much more conductive electrode. We fabricate hybrid silicon/organic heterojunction photovoltaic devices, which have ITO-free, solution processed, and laser processed transparent electrodes. Furthermore, devices which have high resistive losses show up to a 35% increase in power conversion efficiency after laser processing. We perform this study over a range of laser fluences, and a range of nanowire area coverage to investigate the sintering mechanism of nanowires inside of a device stack. The increase in device performance is modeled using a simple photovoltaic diode approach and compares favorably to the experimental data.

  3. 3D Hollow Framework Silver Nanowire Electrodes for High-Performance Bottom-Contact Organic Transistors.

    PubMed

    Kim, Jiye; Lee, So Hee; Kim, Haekyoung; Kim, Se Hyun; Park, Chan Eon

    2015-07-01

    We successfully fabricated high performance bottom-contact organic field-effect transistors (OFETs) using silver nanowire (AgNW) network electrodes by spray deposition. The synthesized AgNWs have the dimensions of 40-80 nm in diameter and 30-80 μm in length and are randomly distributed and interconnected to form a 3D hollow framework. The AgNWs networks, deposited by spray coating, yield an average optical transmittance of up to 88% and a sheet resistance as low as 10 ohm/sq. For using AgNWs as source/drain electrodes of OFETs with a bottom-contact configuration, the large contact resistance at the AgNWs/organic channel remains a critical issue for charge injection. To enhance charge injection, we fabricate semiconductor crystals on the AgNW using an adsorbed residual poly(N-vinylpyrrolidone) layer. The resulting bottom-contact OFETs exhibit high mobility up to 1.02 cm(2)/(V s) and are similar to that of the top-contact Au electrodes OFETs with low contact resistance. A morphological study shows that the pentacene crystals coalesced to form continuous morphology on the nanowires and are highly interconnected with those on the channel. These features contribute to efficient charge injection and encourage the improvement of the bottom-contact device performance. Furthermore, the large contact area of individual AgNWs spreading out to the channel at the edge of the electrode also improves device performance.

  4. Silver nanowire/optical adhesive coatings as transparent electrodes for flexible electronics.

    PubMed

    Miller, Michael S; O'Kane, Jessica C; Niec, Adrian; Carmichael, R Stephen; Carmichael, Tricia Breen

    2013-10-23

    We present new flexible, transparent, and conductive coatings composed of an annealed silver nanowire network embedded in a polyurethane optical adhesive. These coatings can be applied to rigid glass substrates as well as to flexible polyethylene terephthalate (PET) plastic and elastomeric polydimethylsiloxane (PDMS) substrates to produce highly flexible transparent conductive electrodes. The coatings are as conductive and transparent as indium tin oxide (ITO) films on glass, but they remain conductive at high bending strains and are more durable to marring and scratching than ITO. Coatings on PDMS withstand up to 76% tensile strain and 250 bending cycles of 15% strain with a negligible increase in electrical resistance. Since the silver nanowire network is embedded at the surface of the optical adhesive, these coatings also provide a smooth surface (root mean squared surface roughness<10 nm), making them suitable as transparent conducting electrodes in flexible light-emitting electrochemical cells. These devices continue to emit light even while being bent to radii as low as 1.5 mm and perform as well as unstrained devices after 20 bending cycles of 25% tensile strain.

  5. Theoretical Study on Sers of Wagging Vibrations of Benzyl Radical Adsorbed on Silver Electrodes

    NASA Astrophysics Data System (ADS)

    Wu, De-Yin; Chen, Yan-Li; Tian, Zhong-Qun

    2016-06-01

    Electrochemical surface-enhanced Raman spectroscopy (EC-SERS) has been used to characterize adsorbed species widely but reaction intermediates rarely on electrodes. In previous studies, the observed SERS signals were proposed from surface benzyl species due to the electrochemical reduction of benzyl chloride on silver electrode surfaces. In this work, we reinvestigated the vibrational assignments of benzyl chloride and benzyl radical as the reaction intermediate. On the basis of density functional theoretical (DFT) calculations and normal mode analysis, our systematical results provide more reasonable new assignments for both surface species. Further, we investigated adsorption configurations, binding energies, and vibrational frequency shifts of benzyl radical interacting with silver. Our calculated results show that the wagging vibration displays significant vibrational frequency shift, strong coupling with some intramolecular modes in the phenyl ring, and significant changes in intensity of Raman signals. The study also provides absolute Raman intensity in benzyl halides and discuss the enhancement effect mainly due to the binding interaction with respect to free benzyl radical.

  6. From DVD to dendritic nanostructure silver electrode for hydrogen peroxide detection.

    PubMed

    Wen, Ying; Lin, Ai-Jing; Chen, Hui-Fen; Jiao, Ying-Zhi; Yang, Hai-Feng

    2013-03-15

    A facile method of multi-potential step-scan has been employed to fabricate the dendritic silver nanostructures on a silver thin film based digital video disc (DVD) electrode. The morphologies of the nanostructures, the chemical composition, and the crystal structure have been characterized by field-emission scanning electron microscopy, energy-dispersed x-ray spectroscopy, and x-ray diffraction, respectively. The electrocatalytic activity of the resulting electrode toward the electro-reduction of hydrogen peroxide (H(2)O(2)) has been examined via cyclic voltammetry and amperometric analysis. The excellent linear relationship between current response and H(2)O(2) concentration is observed in the range from 5.88×10(-7) to 6.73×10(-5) mol L(-1) and the detection limit is 2×10(-7) mol L(-1) (S/N=3). The as-developed method has been employed to determine H(2)O(2) concentration in real samples. PMID:23017675

  7. Improvements in purification of silver nanowires by decantation and fabrication of flexible transparent electrodes. Application to capacitive touch sensors.

    PubMed

    Mayousse, Céline; Celle, Caroline; Moreau, Eléonore; Mainguet, Jean-François; Carella, Alexandre; Simonato, Jean-Pierre

    2013-05-31

    Transparent flexible electrodes made of metallic nanowires, and in particular silver nanowires (AgNWs), appear as an extremely promising alternative to transparent conductive oxides for future optoelectronic devices. Though significant progresses have been made the last few years, there is still some room for improvement regarding the synthesis of high quality silver nanowire solutions and fabrication process of high performance electrodes. We show that the commonly used purification process can be greatly simplified through decantation. Using this process it is possible to fabricate flexible electrodes by spray coating with sheet resistance lower than 25 Ω sq⁻¹ at 90% transparency in the visible spectrum. These electrodes were used to fabricate an operative transparent flexible touch screen. To our knowledge this is the first reported AgNW based touch sensor relying on capacitive technology. PMID:23619480

  8. Chemically prepared silver electrode for determination of N-acetyl-L-cysteine by flow-injection potentiometry.

    PubMed

    Kolar, M; Dobcnik, D

    2003-01-01

    This paper describes the use of the silver electrode by means of chemical pretreatment of the electrode surface with mercuric(II) chloride solution and potassium iodide solution in flow injection analysis (FIA). The electrode is used as a potentiometric sensor for the indirect determination of NAC in a carrier stream containing iodine. A one-channel flow system that consists of a peristaltic pump, injection valve, a silver wire electrode and a saturated calomel reference electrode (SCE) was used. Some typical FIA parameters such as flow rate, tube length and composition of the carrier stream were varied. The electrode is further characterised by a constant linear response within the concentration range for NAC between 4.0 x 10(-6) and 1.0 x 10(-3) M at the slope of 60.6 +/- 1.0 mV/p(NAC). Some pharmaceutical products containing NAC were also tested. These results can be compared to the results obtained by the direct potentiometric titrations with silver nitrate and are also in good agreement with values declared by pharmaceutical manufacturers.

  9. Silver nanowire based flexible electrodes with improved properties: High conductivity, transparency, adhesion and low haze

    SciTech Connect

    Kiran Kumar, A.B.V.; Wan Bae, Chang; Piao, Longhai Kim, Sang-Ho

    2013-08-01

    Graphical abstract: This graphical abstract illustrates the schematic representation of the main drawbacks and rectifications for AgNWs based transparent electrodes. - Highlights: • Films exhibited low sheet resistance and optical properties with R{sub s} ≤ 30 Ω/□ and T ≥ 90%. • We decreased haze to 2% by controlling AgNWs length, diameter, and concentration. • We achieved good adhesion for AgNWs on PET film. • There is no significant change in resistance in the bending angle from 0° to 180°, and on twisting. - Abstract: Recent work has been focusing on solution processable transparent electrodes for various applications including solar cells and displays. As well as, the research aims majorly at silver nanowires (AgNWs) to replace ITO. We enhance the transparent electrode performance as a function of optical and mechanical properties with low sheet resistance, by controlling the AgNWs accept ratios, ink composition, and processing conditions. The nanowire network of transparent films agrees with the 2D percolation law. The film transmittance values at 550 nm are coping with a reference ITO film. Sheet resistance and haze values are suitable for flexible electronic applications. We fabricate transparent flexible film using a low-cost processing technique.

  10. Highly Reliable Silver Nanowire Transparent Electrode Employing Selectively Patterned Barrier Shaped by Self-Masked Photolithography.

    PubMed

    Wang, Jun; Jiu, Jinting; Sugahara, Tohru; Nagao, Shijo; Nogi, Masaya; Koga, Hirotaka; He, Peng; Suganuma, Katsuaki; Uchida, Hiroshi

    2015-10-21

    The transparent electrode based on silver nanowire (AgNW) networks is one promising alternative of indium tin oxide film in particular for advanced flexible and printable electronics. However, the widespread application of AgNW electrode is hindered by its poor long-term reliability. Although the reliability can be improved by applying traditional overcoating layer or the core-shell structure, the transmittance or conductivity is inevitably undermined. In this paper, a novel patterned barrier of photoresist in situ assembled on the nanowire surface realized the reliability enhancement by simply employing AgNWs themselves as the mask in the photolithography process. The patterned barrier selectively covered the nanowires, while keeping the high transmittance and conductivity unchanged and improving the adhesion of AgNW networks on substrate. After 720 h storage in 85 °C/85% relative humidity (RH) environment, the resistance of electrode with patterned barrier only increased by 0.72 times. This study proposes a new way, i.e., the in situ patterned barrier containing light-sensitive substance, to selectively protect AgNW networks, which can be expanded to various metallic networks including nanowires, nanorods, nanocables, electrospun nanofibers, and so on.

  11. Aligned silver nanowire-based transparent electrodes for engineering polarisation-selective optoelectronics

    PubMed Central

    Park, Byoungchoo; Bae, In-Gon; Huh, Yoon Ho

    2016-01-01

    We herein report on a remarkably simple, fast, and economic way of fabricating homogeneous and well oriented silver nanowires (AgNWs) that exhibit strong in-plane electrical and optical anisotropies. Using a small quantity of AgNW suspension, the horizontal-dip (H-dip) coating method was applied, in which highly oriented AgNWs were deposited unidirectionally along the direction of coating over centimetre-scale lengths very rapidly. In applying the H-dip-coating method, we adjusted the shear strain rate of the capillary flow in the Landau-Levich meniscus of the AgNW suspension, which induced a high degree of uniaxial orientational ordering (0.37–0.43) of the AgNWs, comparable with the ordering seen in archetypal nematic liquid crystal (LC) materials. These AgNWs could be used to fabricate not only transparent electrodes, but also LC-alignment electrodes for LC devices and/or polarising electrodes for organic photovoltaic devices, having the potential to revolutionise the architectures of a number of polarisation-selective opto-electronic devices for use in printed/organic electronics. PMID:26778621

  12. Aligned silver nanowire-based transparent electrodes for engineering polarisation-selective optoelectronics

    NASA Astrophysics Data System (ADS)

    Park, Byoungchoo; Bae, In-Gon; Huh, Yoon Ho

    2016-01-01

    We herein report on a remarkably simple, fast, and economic way of fabricating homogeneous and well oriented silver nanowires (AgNWs) that exhibit strong in-plane electrical and optical anisotropies. Using a small quantity of AgNW suspension, the horizontal-dip (H-dip) coating method was applied, in which highly oriented AgNWs were deposited unidirectionally along the direction of coating over centimetre-scale lengths very rapidly. In applying the H-dip-coating method, we adjusted the shear strain rate of the capillary flow in the Landau-Levich meniscus of the AgNW suspension, which induced a high degree of uniaxial orientational ordering (0.37–0.43) of the AgNWs, comparable with the ordering seen in archetypal nematic liquid crystal (LC) materials. These AgNWs could be used to fabricate not only transparent electrodes, but also LC-alignment electrodes for LC devices and/or polarising electrodes for organic photovoltaic devices, having the potential to revolutionise the architectures of a number of polarisation-selective opto-electronic devices for use in printed/organic electronics.

  13. Interface Roughening Dynamics of Spreading Droplets

    NASA Astrophysics Data System (ADS)

    Taitelbaum, Haim; Be'Er, Avraham; Hecht, Inbal; Frydman, Aviad; Lereah, Yossi

    2006-03-01

    We review our recent experimental data of interface roughening dynamics of spreading mercury droplets on thin films (silver or gold), obtained using optical microscopy and other techniques (AFM, SEM). We discuss the various results obtained for the roughness and growth exponents associated with the interface dynamics, and their universality classes. We analyze the temporal width fluctuations, obtained for single interfaces, and show that these fluctuations contain information on the lateral correlation length of these interfaces. We show how to extract this length from experimental data, and demonstrate the validity of this method in a wide range of growing interfaces (droplet spreading experiments as well as water imbibition on paper). References: 1. A. Be'er, Y. Lereah and H. Taitelbaum, Physica A, 285, 156 (2000). 2. A. Be'er, Y. Lereah, I. Hecht and H. Taitelbaum, Physica A, 302, 297 (2001). 3. A. Be'er, Y. Lereah, A. Frydman and H. Taitelbaum, Physica A, 314, 325 (2002). 4. A. Be'er and Y. Lereah, J. of Microscopy, 208, 148 (2002). 5. I. Hecht and H. Taitelbaum, Phys. Rev. E, 70, 046307 (2004). 6. A. Be'er, I. Hecht and H. Taitelbaum, Phys. Rev. E, 72, 031606 (2005). 7. I. Hecht, A. Be'er and H. Taitelbaum, Fluctuation and Noise Letters, 5, L319 (2005).

  14. Electrostatic spray deposition of highly transparent silver nanowire electrode on flexible substrate.

    PubMed

    Kim, Taegeon; Canlier, Ali; Kim, Geun Hong; Choi, Jaeho; Park, Minkyu; Han, Seung Min

    2013-02-01

    In this work, a modified polyol synthesis by adding KBr and by replacing the AgCl with NaCl seed was used to obtain high quality silver nanowires with long aspect ratios with an average length of 13.5 μm in length and 62.5 nm in diameter. The Ag nanowires suspended in methanol solution after removing any unwanted particles using a glass filter system were then deposited on a flexible polycarbonate substrate using an electrostatic spray system. Transmittance of 92.1% at wavelength of 550 nm with sheet resistance of 20 Ω/sq and haze of 4.9% were measured for the electrostatic sprayed Ag nanowire transparent electrode.

  15. Transferable self-welding silver nanowire network as high performance transparent flexible electrode.

    PubMed

    Zhu, Siwei; Gao, Yuan; Hu, Bin; Li, Jia; Su, Jun; Fan, Zhiyong; Zhou, Jun

    2013-08-23

    High performance transparent electrodes (TEs) with figures-of-merit as high as 471 were assembled using ultralong silver nanowires (Ag NWs). A room-temperature plasma was employed to enhance the conductivity of the Ag NW TEs by simultaneously removing the insulating PVP layer coating on the NWs and welding the junctions tightly. Furthermore, we developed a general way to fabricate TEs regardless of substrate limitations by transferring the as-fabricated Ag NW network onto various substrates directly, and the transmittance can remain as high as 91% with a sheet resistivity of 13 Ω/sq. The highly robust and stable flexible TEs will have broad applications in flexible optoelectronic and electronic devices.

  16. Low temperature processed planar heterojunction perovskite solar cells employing silver nanowires as top electrode

    NASA Astrophysics Data System (ADS)

    Zhang, Jianhua; Li, Fushan; Yang, Kaiyu; Veeramalai, Chandrasekar Perumal; Guo, Tailiang

    2016-04-01

    In this paper, we reported a low temperature processed planar heterojunction perovskite solar cell employing silver nanowires as the top electrode and ZnO nanoparticles as the electron transport layer. The CH3NH3PbI3 perovskite was grown as the light absorber via two-step spin-coating technique. The as-fabricated perovskite solar cell exhibited the highest power conversion efficiency of 9.21% with short circuit current density of 19.75 mA cm-2, open circuit voltage of 1.02, and fill factor value of 0.457. The solar cell's performance showed negligible difference between the forward and reverse bias scan. This work paves a way for realizing low cost solution processable solar cells.

  17. Solution-processed parallel tandem polymer solar cells using silver nanowires as intermediate electrode.

    PubMed

    Guo, Fei; Kubis, Peter; Li, Ning; Przybilla, Thomas; Matt, Gebhard; Stubhan, Tobias; Ameri, Tayebeh; Butz, Benjamin; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J

    2014-12-23

    Tandem architecture is the most relevant concept to overcome the efficiency limit of single-junction photovoltaic solar cells. Series-connected tandem polymer solar cells (PSCs) have advanced rapidly during the past decade. In contrast, the development of parallel-connected tandem cells is lagging far behind due to the big challenge in establishing an efficient interlayer with high transparency and high in-plane conductivity. Here, we report all-solution fabrication of parallel tandem PSCs using silver nanowires as intermediate charge collecting electrode. Through a rational interface design, a robust interlayer is established, enabling the efficient extraction and transport of electrons from subcells. The resulting parallel tandem cells exhibit high fill factors of ∼60% and enhanced current densities which are identical to the sum of the current densities of the subcells. These results suggest that solution-processed parallel tandem configuration provides an alternative avenue toward high performance photovoltaic devices. PMID:25405589

  18. Performance improvement in flexible polymer solar cells based on modified silver nanowire electrode

    NASA Astrophysics Data System (ADS)

    Wang, Danbei; Zhou, Weixin; Liu, Huan; Ma, Yanwen; Zhang, Hongmei

    2016-08-01

    In this work, an efficient flexible polymer solar cell was achieved by controlling the UV-ozone treatment time of silver nanowires (Ag NWs) used in the electrode and combined with other modification materials. Through optimizing the time of UV-ozone treatment, it is shown that Ag NWs electrode treated by UV-ozone for 10 s improves the power conversion efficiency (PCE) of the device based on the blend of poly(3-hexylthiophene)(P3HT): [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) from 0.76% to 1.34%. After treatment by UV-ozone, Ag NWs electrodes exhibit several promising characteristics, including high optical transparency, low sheet resistance and superior surface work function. As a consequence, the performance of devices utilizing 10 s UV-ozone-treated Ag NWs with PEDOT:PSS or MoO3 as composite anode showed higher PCEs of 2.77% (2.73%) compared with that for Ag NW electrodes without UV-ozone treatment. In addition, a PCE of 5.97% in flexible polymer solar cells based on poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b0]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl](PBDTTT-EFT):[6, 6]-phenyl C71-butyric acid methyl ester (PC71BM) as a photoactive layer was obtained.

  19. Stability of silver nanowire based electrodes under environmental and electrical stresses

    NASA Astrophysics Data System (ADS)

    Mayousse, Céline; Celle, Caroline; Fraczkiewicz, Alexandra; Simonato, Jean-Pierre

    2015-01-01

    Flexible transparent electrodes fabricated with random networks of silver nanowires (AgNWs) have been widely studied in recent years. This approach appears to be a promising alternative to replace ITO (indium tin oxide) in many optoelectronic applications. Many successful integrations in functional devices have already evidenced the high potential of this technology, but unfortunately only very few studies have been dedicated so far to the stability of this material. We present here a study dealing with the alteration of the electrical properties of AgNW meshes when subjected to different stresses. We demonstrate that AgNW electrodes are very stable when stored under ambient atmosphere up to, at least, two and a half years. Accelerated ageing processes also reveal that concentrated H2S or exposure to light does not cause any significant sheet resistance modification. However, the combination of high relative humidity and high temperature seems to be more critical. In addition, long lasting contact (two years) with PEDOT:PSS can induce deterioration of the electrical properties. Similarly, AgNW/PEDOT:PSS hybrid materials exhibit weaker stability under electrical stress when compared to pristine AgNW networks.Flexible transparent electrodes fabricated with random networks of silver nanowires (AgNWs) have been widely studied in recent years. This approach appears to be a promising alternative to replace ITO (indium tin oxide) in many optoelectronic applications. Many successful integrations in functional devices have already evidenced the high potential of this technology, but unfortunately only very few studies have been dedicated so far to the stability of this material. We present here a study dealing with the alteration of the electrical properties of AgNW meshes when subjected to different stresses. We demonstrate that AgNW electrodes are very stable when stored under ambient atmosphere up to, at least, two and a half years. Accelerated ageing processes also

  20. A highly sensitive and flexible pressure sensor with electrodes and elastomeric interlayer containing silver nanowires.

    PubMed

    Wang, Jun; Jiu, Jinting; Nogi, Masaya; Sugahara, Tohru; Nagao, Shijo; Koga, Hirotaka; He, Peng; Suganuma, Katsuaki

    2015-02-21

    The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present study a simple printing process without complex patterning has been used for constructing the sensor, and an interlayer is employed comprising elastomeric composites filled with silver nanowires. By increasing the relative permittivity, εr, of the composite interlayer induced by compression at high nanowire concentration, it has been possible to achieve a maximum sensitivity of 5.54 kPa(-1). The improvement in sensitivity did not sacrifice or undermine the other features of the sensor. Thanks to the silver nanowire electrodes, the sensor is flexible and stable after 200 cycles at a bending radius of 2 mm, and exhibits outstanding reproducibility without hysteresis under similar pressure pulses. The sensor has been readily integrated onto an adhesive bandage and has been successful in detecting human movements. In addition to measuring pressure in direct contact, non-contact pressures such as air flow can also be detected.

  1. Using Silver Nano-Particle Ink in Electrode Fabrication of High Frequency Copolymer Ultrasonic Transducers: Modeling and Experimental Investigation

    PubMed Central

    Decharat, Adit; Wagle, Sanat; Jacobsen, Svein; Melandsø, Frank

    2015-01-01

    High frequency polymer-based ultrasonic transducers are produced with electrodes thicknesses typical for printed electrodes obtained from silver (Ag) nano-particle inks. An analytical three-port network is used to study the acoustic effects imposed by a thick electrode in a typical layered transducer configuration. Results from the network model are compared to experimental findings for the implemented transducer configuration, to obtain a better understanding of acoustical effects caused by the additional printed mass loading. The proposed investigation might be supportive of identification of suitable electrode-depositing methods. It is also believed to be useful as a feasibility study for printed Ag-based electrodes in high frequency transducers, which may reduce both the cost and production complexity of these devices. PMID:25903552

  2. Silver Nanowire Transparent Conductive Electrodes for High-Efficiency III-Nitride Light-Emitting Diodes

    PubMed Central

    Oh, Munsik; Jin, Won-Yong; Jun Jeong, Hyeon; Jeong, Mun Seok; Kang, Jae-Wook; Kim, Hyunsoo

    2015-01-01

    Silver nanowires (AgNWs) have been successfully demonstrated to function as next-generation transparent conductive electrodes (TCEs) in organic semiconductor devices owing to their figures of merit, including high optical transmittance, low sheet resistance, flexibility, and low-cost processing. In this article, high-quality, solution-processed AgNWs with an excellent optical transmittance of 96.5% at 450 nm and a low sheet resistance of 11.7 Ω/sq were demonstrated as TCEs in inorganic III-nitride LEDs. The transmission line model applied to the AgNW contact to p-GaN showed that near ohmic contact with a specific contact resistance of ~10−3 Ωcm2 was obtained. The contact resistance had a strong bias-voltage (or current-density) dependence: namely, field-enhanced ohmic contact. LEDs fabricated with AgNW electrodes exhibited a 56% reduction in series resistance, 56.5% brighter output power, a 67.5% reduction in efficiency droop, and a approximately 30% longer current spreading length compared to LEDs fabricated with reference TCEs. In addition to the cost reduction, the observed improvements in device performance suggest that the AgNWs are promising for application as next-generation TCEs, to realise brighter, larger-area, cost-competitive inorganic III-nitride light emitters. PMID:26333768

  3. Silver Nanowire Transparent Conductive Electrodes for High-Efficiency III-Nitride Light-Emitting Diodes.

    PubMed

    Oh, Munsik; Jin, Won-Yong; Jeong, Hyeon Jun; Jeong, Mun Seok; Kang, Jae-Wook; Kim, Hyunsoo

    2015-01-01

    Silver nanowires (AgNWs) have been successfully demonstrated to function as next-generation transparent conductive electrodes (TCEs) in organic semiconductor devices owing to their figures of merit, including high optical transmittance, low sheet resistance, flexibility, and low-cost processing. In this article, high-quality, solution-processed AgNWs with an excellent optical transmittance of 96.5% at 450 nm and a low sheet resistance of 11.7 Ω/sq were demonstrated as TCEs in inorganic III-nitride LEDs. The transmission line model applied to the AgNW contact to p-GaN showed that near ohmic contact with a specific contact resistance of ~10(-3) Ωcm(2) was obtained. The contact resistance had a strong bias-voltage (or current-density) dependence: namely, field-enhanced ohmic contact. LEDs fabricated with AgNW electrodes exhibited a 56% reduction in series resistance, 56.5% brighter output power, a 67.5% reduction in efficiency droop, and a approximately 30% longer current spreading length compared to LEDs fabricated with reference TCEs. In addition to the cost reduction, the observed improvements in device performance suggest that the AgNWs are promising for application as next-generation TCEs, to realise brighter, larger-area, cost-competitive inorganic III-nitride light emitters.

  4. Silver Nanowire Transparent Conductive Electrodes for High-Efficiency III-Nitride Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Oh, Munsik; Jin, Won-Yong; Jun Jeong, Hyeon; Jeong, Mun Seok; Kang, Jae-Wook; Kim, Hyunsoo

    2015-09-01

    Silver nanowires (AgNWs) have been successfully demonstrated to function as next-generation transparent conductive electrodes (TCEs) in organic semiconductor devices owing to their figures of merit, including high optical transmittance, low sheet resistance, flexibility, and low-cost processing. In this article, high-quality, solution-processed AgNWs with an excellent optical transmittance of 96.5% at 450 nm and a low sheet resistance of 11.7 Ω/sq were demonstrated as TCEs in inorganic III-nitride LEDs. The transmission line model applied to the AgNW contact to p-GaN showed that near ohmic contact with a specific contact resistance of ~10-3 Ωcm2 was obtained. The contact resistance had a strong bias-voltage (or current-density) dependence: namely, field-enhanced ohmic contact. LEDs fabricated with AgNW electrodes exhibited a 56% reduction in series resistance, 56.5% brighter output power, a 67.5% reduction in efficiency droop, and a approximately 30% longer current spreading length compared to LEDs fabricated with reference TCEs. In addition to the cost reduction, the observed improvements in device performance suggest that the AgNWs are promising for application as next-generation TCEs, to realise brighter, larger-area, cost-competitive inorganic III-nitride light emitters.

  5. Optimization of silver nanowire-based transparent electrodes: effects of density, size and thermal annealing

    NASA Astrophysics Data System (ADS)

    Lagrange, M.; Langley, D. P.; Giusti, G.; Jiménez, C.; Bréchet, Y.; Bellet, D.

    2015-10-01

    Silver nanowire (AgNW) networks are efficient as flexible transparent electrodes, and are cheaper to fabricate than ITO (Indium Tin Oxide). Hence they are a serious competitor as an alternative to ITO in many applications such as solar cells, OLEDs, transparent heaters. Electrical and optical properties of AgNW networks deposited on glass are investigated in this study and an efficient method to optimize them is proposed. This paper relates network density, nanowire dimensions and thermal annealing directly to the physical properties of the nanowire networksusing original physical models. A fair agreement is found between experimental data and the proposed models. Moreover thermal stability of the nanowires is a key issue in thermal optimization of such networks and needs to be studied. In this work the impact of these four parameters on the networks physical properties are thoroughly investigated via in situ measurements and modelling, such a method being also applicable to other metallic nanowire networks. We demonstrate that this approach enables the optimization of both optical and electrical properties through modification of the junction resistance by thermal annealing, and a suitable choice of nanowire dimensions and network density. This work reports excellent optical and electrical properties of electrodes fabricated from AgNW networks with a transmittance T = 89.2% (at 550 nm) and a sheet resistance of Rs = 2.9 Ω □-1, leading to the highest reported figure of merit.

  6. Development of Silver-Free Silicon Photovoltaic Solar Cells with All-Aluminum Electrodes

    NASA Astrophysics Data System (ADS)

    Sun, Wen-Cheng

    To date, the most popular and dominant material for commercial solar cells is crystalline silicon (or wafer-Si). It has the highest cell efficiency and cell lifetime out of all commercial solar cells. Although the potential of crystalline-Si solar cells in supplying energy demands is enormous, their future growth will likely be constrained by two major bottlenecks. The first is the high electricity input to produce crystalline-Si solar cells and modules, and the second is the limited supply of silver (Ag) reserves. These bottlenecks prevent crystalline-Si solar cells from reaching terawatt-scale deployment, which means the electricity produced by crystalline-Si solar cells would never fulfill a noticeable portion of our energy demands in the future. In order to solve the issue of Ag limitation for the front metal grid, aluminum (Al) electroplating has been developed as an alternative metallization technique in the fabrication of crystalline-Si solar cells. The plating is carried out in a near-room-temperature ionic liquid by means of galvanostatic electrolysis. It has been found that dense, adherent Al deposits with resistivity in the high 10--6 Ω-cm range can be reproducibly obtained directly on Si substrates and nickel seed layers. An all-Al Si solar cell, with an electroplated Al front electrode and a screen-printed Al back electrode, has been successfully demonstrated based on commercial p-type monocrystalline-Si solar cells, and its efficiency is approaching 15%. Further optimization of the cell fabrication process, in particular a suitable patterning technique for the front silicon nitride layer, is expected to increase the efficiency of the cell to ~18%. This shows the potential of Al electroplating in cell metallization is promising and replacing Ag with Al as the front finger electrode is feasible.

  7. High-Performance Silver Window Electrodes for Top-Illuminated Organic Photovoltaics Using an Organo-molybdenum Oxide Bronze Interlayer.

    PubMed

    Tyler, Martin S; Walker, Marc; Hatton, Ross A

    2016-05-18

    We report an organo-molybdenumn oxide bronze that enables the fabrication of high-performance silver window electrodes for top-illuminated solution processed organic photovoltaics without complicating the process of device fabrication. This hybrid material combines the function of wide-band-gap interlayer for efficient hole extraction with the role of metal electrode seed layer, enabling the fabrication of highly transparent, low-sheet-resistance silver window electrodes. Additionally it is also processed from ethanol, which ensures orthogonality with a large range of solution processed organic semiconductors. The key organic component is the low cost small molecule 3-mercaptopropionic acid, which (i) promotes metal film formation and imparts robustness at low metal thickness, (ii) reduces the contact resistance at the Ag/molybdenumn oxide bronze interface, (iii) and greatly improves the film forming properties. Silver electrodes with a thickness of 8 nm deposited by simple vacuum evaporation onto this hybrid interlayer have a sheet resistance as low as 9.7 Ohms per square and mean transparency ∼80% over the wavelength range 400-900 nm without the aid of an antireflecting layer, which makes them well-matched to the needs of organic photovoltaics and applicable to perovskite photovoltaics. The application of this hybrid material is demonstrated in two types of top-illuminated organic photovoltaic devices.

  8. A highly sensitive and flexible pressure sensor with electrodes and elastomeric interlayer containing silver nanowires

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Jiu, Jinting; Nogi, Masaya; Sugahara, Tohru; Nagao, Shijo; Koga, Hirotaka; He, Peng; Suganuma, Katsuaki

    2015-02-01

    The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present study a simple printing process without complex patterning has been used for constructing the sensor, and an interlayer is employed comprising elastomeric composites filled with silver nanowires. By increasing the relative permittivity, εr, of the composite interlayer induced by compression at high nanowire concentration, it has been possible to achieve a maximum sensitivity of 5.54 kPa-1. The improvement in sensitivity did not sacrifice or undermine the other features of the sensor. Thanks to the silver nanowire electrodes, the sensor is flexible and stable after 200 cycles at a bending radius of 2 mm, and exhibits outstanding reproducibility without hysteresis under similar pressure pulses. The sensor has been readily integrated onto an adhesive bandage and has been successful in detecting human movements. In addition to measuring pressure in direct contact, non-contact pressures such as air flow can also be detected.The next-generation application of pressure sensors is gradually being extended to include electronic artificial skin (e-skin), wearable devices, humanoid robotics and smart prosthetics. In these advanced applications, high sensing capability is an essential feature for high performance. Although surface patterning treatments and some special elastomeric interlayers have been applied to improve sensitivity, the process is complex and this inevitably raises the cost and is an obstacle to large-scale production. In the present

  9. In-Situ Roughening of Polymeric Microstructures

    PubMed Central

    Shadpour, Hamed; Allbritton, Nancy L.

    2010-01-01

    A method to perform in-situ roughening of arrays of microstructures weakly adherent to an underlying substrate was presented. SU8, 1002F, and polydimethylsiloxane (PDMS) microstructures were roughened by polishing with a particle slurry. The roughness and the percentage of dislodged or damaged microstructures was evaluated as a function of the roughening time for both SU8 and 1002F structures. A maximal RMS roughness of 7-18 nm for the surfaces was obtained within 15 to 30 s of polishing with the slurry. This represented a 4-9 fold increase in surface roughness relative to that of the native surface. Less than 0.8% of the microstructures on the array were removed or damage after 5 min of polishing. Native and roughened arrays were assessed for their ability to support fibronectin adhesion and cell attachment and growth. The quantity of adherent fibronectin was increased on roughened arrays by two-fold over that on native arrays. Cell adhesion to the roughened surfaces was also increased compared to native surfaces. Surface roughening with the particle slurry also improved the ability to stamp molecules onto the substrate during microcontact printing. Roughening both the PDMS stamp and substrate resulted in up to a 20-fold improvement in the transfer of BSA-Alexa Fluor 647 from the stamp to the substrate. Thus roughening of micron-scale surfaces with a particle slurry increased the adhesion of biomolecules as well as cells to microstructures with little to no damage to large scale arrays of the structures. PMID:20423129

  10. Photocatalytic, antimicrobial activities of biogenic silver nanoparticles and electrochemical degradation of water soluble dyes at glassy carbon/silver modified past electrode using buffer solution.

    PubMed

    Khan, Zia Ul Haq; Khan, Amjad; Shah, Afzal; Chen, Yongmei; Wan, Pingyu; Khan, Arif Ullah; Tahir, Kamran; Muhamma, Nawshad; Khan, Faheem Ullah; Shah, Hidayat Ullah

    2016-03-01

    In the present research work a novel, nontoxic and ecofriendly procedure was developed for the green synthesis of silver nano particle (AgNPs) using Caruluma edulis (C. edulis) extract act as reductant as well as stabilizer agents. The formation of AgNPs was confirmed by UV/Vis spectroscopy. The small and spherical sizes of AgNPs were conformed from high resolution transmission electron microscopy (HRTEM) analysis and were found in the range of 2-10nm, which were highly dispersion without any aggregation. The crystalline structure of AgNPs was conformed from X-ray diffraction (XRD) analysis. For the elemental composition EDX was used and FTIR helped to determine the type of organic compounds in the extract. The potential electrochemical property of modified silver electrode was also studied. The AgNPs showed prominent antibacterial motion with MIC values of 125 μg/mL against Bacillus subtilis and Staphylococcus aureus while 250 μg/mL against Escherichia coli. High cell constituents' release was exhibited by B. subtilis with 2 × MIC value of silver nanoparticles. Silver nanoparticles also showed significant DPPH free radical scavenging activity. This research would have an important implication for the synthesis of more efficient antimicrobial and antioxidant agent. The AgNP modified electrode (GC/AgNPs) exhibited an excellent electro-catalytic activity toward the redox reaction of phenolic compounds. The AgNPs were evaluated for electrochemical degradation of bromothymol blue (BTB) dyes which showed a significant activity. From the strong reductive properties it is obvious that AgNPs can be used in water sanitization and converting some organic perilous in to non-hazardous materials. The AgNPs showed potential applications in the field of electro chemistry, sensor, catalyst, nano-devices and medical.

  11. Towards combined electrochemistry and surface-enhanced resonance Raman of heme proteins: Improvement of diffusion electrochemistry of cytochrome c at silver electrodes chemically modified with 4-mercaptopyridine.

    PubMed

    Millo, Diego; Ranieri, Antonio; Koot, Wynanda; Gooijer, Cees; van der Zwan, Gert

    2006-08-01

    To date, a successful combination of surface-enhanced resonance Raman spectroscopy (SERRS) and electrochemistry to study heme proteins is inhibited by the problems raised by the prerequisite to use silver as electrode metal. This paper indicates an approach to overcome these problems. It describes a quick and reproducible procedure to prepare silver electrodes chemically modified with 4-mercaptopyridine suitable to perform diffusion electrochemistry of cytochrome c (cyt c). The method involves the employment of a mechanical and a chemical treatment and avoids the use of alumina slurries and any electrochemical pretreatment. Cyclic voltammetry (CV) was used to test the electrochemical response of cyt c, and the CV signals were found identical with those obtained on gold electrodes under the same experimental conditions. Compared to previous literature, a significant improvement of the CV signal of cyt c at silver electrodes was achieved. Preliminary results show that this treatment can be also successfully employed for the preparation of SERRS-active electrodes.

  12. Modified carbon-free silver electrodes for the use as cathodes in lithium-air batteries with an aqueous alkaline electrolyte

    NASA Astrophysics Data System (ADS)

    Wittmaier, Dennis; Wagner, Norbert; Friedrich, K. Andreas; Amin, Hatem M. A.; Baltruschat, Helmut

    2014-11-01

    Gas diffusion electrodes with silver catalysts show a high activity towards oxygen reduction reaction in alkaline media but a rather poor activity towards oxygen evolution reaction. For the use in future lithium-air batteries with an aqueous alkaline electrolyte the activity of such electrodes must be improved significantly. As Co3O4 is a promising metal oxide catalyst for oxygen evolution in alkaline media, silver electrodes were modified with Co3O4. For comparison silver electrodes were also modified with IrO2. Due to the poor stability of carbon materials at high anodic potentials these gas diffusion electrodes were prepared without carbon support to improve especially the long-term stability. Gas diffusion electrodes were electrochemically investigated in an electrochemical half-cell arrangement. In addition to cyclic voltammograms electrochemical impedance spectroscopy (EIS) was carried out. SEM and XRD were used for the physical and morphological investigations. Investigations showed that silver electrodes containing 20 wt.% Co3O4 exhibited the highest performance and highest long-term stability. For comparison, rotating - ring - disc - electrode experiments have been performed using model electrodes with thin catalyst layers, showing that the amount of hydrogen peroxide evolved is negligible.

  13. Electrical limit of silver nanowire electrodes: Direct measurement of the nanowire junction resistance

    NASA Astrophysics Data System (ADS)

    Selzer, Franz; Floresca, Carlo; Kneppe, David; Bormann, Ludwig; Sachse, Christoph; Weiß, Nelli; Eychmüller, Alexander; Amassian, Aram; Müller-Meskamp, Lars; Leo, Karl

    2016-04-01

    We measure basic network parameters of silver nanowire (AgNW) networks commonly used as transparent conducting electrodes in organic optoelectronic devices. By means of four point probing with nanoprobes, the wire-to-wire junction resistance and the resistance of single nanowires are measured. The resistance RNW of a single nanowire shows a value of RNW=(4.96 ±0.18 ) Ω/μm . The junction resistance RJ differs for annealed and non-annealed NW networks, exhibiting values of RJ=(25.2 ±1.9 ) Ω (annealed) and RJ=(529 ±239 ) Ω (non-annealed), respectively. Our simulation achieves a good agreement between the measured network parameters and the sheet resistance RS of the entire network. Extrapolating RJ to zero, our study show that we are close to the electrical limit of the conductivity of our AgNW system: We obtain a possible RS reduction by only ≈20 % (common RS≈10 Ω/sq ). Therefore, we expect further performance improvements in AgNW systems mainly by increasing NW length or by utilizing novel network geometries.

  14. The role of chloride ions in rapid synthesis of ultra-long silver nanowires for flexible electrodes

    NASA Astrophysics Data System (ADS)

    Wang, Shang; Tian, Yanhong; Ding, Su; Wang, Chunqing

    2016-07-01

    Ultra-long silver nanowires (AgNWs) could be an ideal material to replace the commercial used indium tin oxide in highly conductive and transparent electrodes field. In this report, AgNWs with mean length of 102 μm and even 268 μm have been synthesized through a rapid and one-step polyol method within only 40 min. The effective synthesis was contributed to the relatively high concentration of Cl‑ which facilitated the generation of silver five-twined seeds by heterogeneous nucleation during the nucleation process. By varying the ratio of Cl‑, AgNWs with various diameters ranging from 60 to 141 nm could be obtained. Moreover, AgNWs based electrodes were prepared on paper and polyethylene terephthalate (PET) substrates and the sheet resistance of the PET based transparent electrode were measured to be 14 Ω sq‑1 at optical transmittance of 87%. The mechanical properties of the ultra-long AgNWs based electrodes were also characterized.

  15. Strain sensitivity and durability in p-type and n-type organic thin-film transistors with printed silver electrodes

    NASA Astrophysics Data System (ADS)

    Fukuda, Kenjiro; Hikichi, Kenta; Sekine, Tomohito; Takeda, Yasunori; Minamiki, Tsukuru; Kumaki, Daisuke; Tokito, Shizuo

    2013-06-01

    Mechanical flexibility and compatibility of printing processes are key advantage that organic electronic devices have over conventional inorganic devices. However, one of the major remaining issues for organic devices is insufficient mechanical durability of printed electrodes. Here we have investigated the mechanical durability of both p-type and n-type organic thin-film transistors (TFTs) with ink-jet printed silver electrodes from silver nanoparticle inks. The modified silver nanoparticle inks enabled the strong adhesion to the underlying polymer layer, and the fabricated organic TFTs exhibited excellent reproducibility in the bending cycle tests. The strong channel length dependence on the strain sensitivity was observed in both p-type and n-type organic TFTs. The organic TFTs with a short-channel exhibited higher sensitivity to the bending strain. These results suggest that the flexible organic TFTs with printed silver electrodes have excellent mechanical durability and are useful for bending and strain sensors.

  16. Strain sensitivity and durability in p-type and n-type organic thin-film transistors with printed silver electrodes

    PubMed Central

    Fukuda, Kenjiro; Hikichi, Kenta; Sekine, Tomohito; Takeda, Yasunori; Minamiki, Tsukuru; Kumaki, Daisuke; Tokito, Shizuo

    2013-01-01

    Mechanical flexibility and compatibility of printing processes are key advantage that organic electronic devices have over conventional inorganic devices. However, one of the major remaining issues for organic devices is insufficient mechanical durability of printed electrodes. Here we have investigated the mechanical durability of both p-type and n-type organic thin-film transistors (TFTs) with ink-jet printed silver electrodes from silver nanoparticle inks. The modified silver nanoparticle inks enabled the strong adhesion to the underlying polymer layer, and the fabricated organic TFTs exhibited excellent reproducibility in the bending cycle tests. The strong channel length dependence on the strain sensitivity was observed in both p-type and n-type organic TFTs. The organic TFTs with a short-channel exhibited higher sensitivity to the bending strain. These results suggest that the flexible organic TFTs with printed silver electrodes have excellent mechanical durability and are useful for bending and strain sensors. PMID:23788235

  17. Silver nanowire composite thin films as transparent electrodes for Cu(In,Ga)Se₂/ZnS thin film solar cells.

    PubMed

    Tan, Xiao-Hui; Chen, Yu; Liu, Ye-Xiang

    2014-05-20

    Solution processed silver nanowire indium-tin oxide nanoparticle (AgNW-ITONP) composite thin films were successfully applied as the transparent electrodes for Cu(In,Ga)Se₂ (CIGS) thin film solar cells with ZnS buffer layers. Properties of the AgNW-ITONP thin film and its effects on performance of CIGS/ZnS thin film solar cells were studied. Compared with the traditional sputtered ITO electrodes, the AgNW-ITONP thin films show comparable optical transmittance and electrical conductivity. Furthermore, the AgNW-ITONP thin film causes no physical damage to the adjacent surface layer and does not need high temperature annealing, which makes it very suitable to use as transparent conductive layers for heat or sputtering damage-sensitive optoelectronic devices. By using AgNW-ITONP electrodes, the required thickness of the ZnS buffer layers for CIGS thin film solar cells was greatly decreased. PMID:24922214

  18. Direct electrochemistry and electrocatalysis of glucose oxidase immobilized on reduced graphene oxide and silver nanoparticles nanocomposite modified electrode.

    PubMed

    Palanisamy, Selvakumar; Karuppiah, Chelladurai; Chen, Shen-Ming

    2014-02-01

    The direct electrochemistry of glucose oxidase (GOx) was successfully realized on electrochemically reduced graphene oxide and silver nanoparticles (RGO/Ag) nanocomposite modified electrode. The fabricated nanocomposite was characterized by field emission scanning electron microscope and energy dispersive spectroscopy. The GOx immobilized nanocomposite modified electrode showed a pair of well-defined redox peaks with a formal potential (E°) of -0.422 V, indicating that the bioactivity of GOx was retained. The heterogeneous electron transfer rate constant (Ks) of GOx at the nanocomposite was calculated to be 5.27 s(-1), revealing a fast direct electron transfer of GOx. The GOx immobilized RGO/Ag nanocomposite electrode exhibited a good electrocatalytic activity toward glucose over a linear concentration range from 0.5 to 12.5 mM with a detection limit of 0.16 mM. Besides, the fabricated biosensor showed an acceptable sensitivity and selectivity for glucose.

  19. The effect of rod orientation on electrical anisotropy in silver nanowire networks for ultra-transparent electrodes

    PubMed Central

    Ackermann, Thomas; Neuhaus, Raphael; Roth, Siegmar

    2016-01-01

    Two-dimensional networks made of metal nanowires are excellent paradigms for the experimental observation of electrical percolation caused by continuous jackstraw-like physical pathways. Such systems became very interesting as alternative material in transparent electrodes, which are fundamental components in display devices. This work presents the experimental characterization of low-haze and ultra-transparent electrodes based on silver nanowires. The films are created by dip-coating, a feasible and scalable liquid film coating technique. We have found dominant alignment of the silver nanowires in withdrawal direction. The impact of this structural anisotropy on electrical anisotropy becomes more pronounced for low area coverage. The rod alignment does not influence the technical usability of the films as significant electrical anisotropy occurs only at optical transmission higher than 99 %. For films with lower transmission, electrical anisotropy becomes negligible. In addition to the experimental work, we have carried out computational studies in order to explain our findings further and compare them to our experiments and previous literature. This paper presents the first experimental observation of electrical anisotropy in two-dimensional silver nanowire networks close at the percolation threshold. PMID:27677947

  20. Adsorption mechanism of physiologically active L-phenylalanine phosphonodipeptide analogues: Comparison of colloidal silver and macroscopic silver substrates

    NASA Astrophysics Data System (ADS)

    Podstawka, E.; Kudelski, A.; Proniewicz, L. M.

    2007-11-01

    Here we present SERS spectra of several L-phenylalanine (Phe) phosphonodipeptides, i.e., L-Phe- L-Ala-PO 3H 2 ( MD1), L-Phe- L-Va L-PO 3H 2 ( MD2), L-Phe-β-Ala-CH(OH)-PO 3H 2 ( MD3), L-Phe- L-Ala-CH(OH)-PO 3H 2 ( MD4), L-Ala-(3,4-dimethoxy)- L-Phe-PO 3H 2 ( MD5), and L-Ala-(3,4-dimethoxy)-(des-CH 2)- L-Phe-PO 3H 2 ( MD6), immobilized on electrochemically roughened silver electrodes. These spectra are analyzed by theoretical calculations using density functional theory (DFT) at the B3LYP level with 6-31++G∗∗ basis set. In addition, these spectra are compared with SERS spectra of these species adsorbed on a colloidal silver surface. We showed that on the macroscopic silver substrate, the Phe aromatic ring of MD3 and MD4 is oriented vertically, while for MD1 it almost "stands up" on this surface. In the other three cases, the Phe ring adopts a tilted orientation in regard to the substrate. We also find that the phosphonate (-PO32-), methyl/methane, or dimethoxy groups of MD1, MD2, MD3, MD5, and MD6 are involved in the interaction of these phosphonodipeptides with the electrochemically roughened surface. This phenomenon is clearly seen for -CH 2-/-CH 3/-OCH 3 moieties as well as for the PO32- group that adsorbs on the macroscopic silver substrates mainly via the P dbnd O fragment. We also showed that MD4 binds to the macroscopic silver substrate through the hydroxyl, amine, and phosphonate groups, while the methylene/methane moieties are remote from this surface. We found that studied phosphonodipeptides often adsorb differently on the macroscopic silver substrate and on the colloidal silver nanoparticles. For example, MD1 adopts an almost vertical orientation on the electrochemically roughened silver substrate and is tilted or close to flat on the silver nanoparticles.

  1. Silver-Copper Nanoalloy Catalyst Layer for Bifunctional Air Electrodes in Alkaline Media.

    PubMed

    Wu, Xiaoqiang; Chen, Fuyi; Jin, Yachao; Zhang, Nan; Johnston, Roy L

    2015-08-19

    A carbon-free and binder-free catalyst layer composed of a Ag-Cu nanoalloy on Ni foam was used as the air cathode in a zinc-air battery for the first time. The Ag-Cu catalyst was prepared using pulsed laser deposition. The structures of the catalysts were found to consist of crystalline Ag-Cu nanoalloy particles with an average size of 2.58 nm embedded in amorphous Cu films. As observed in the X-ray photoelectron spectra, the Ag 3d core levels shifted to higher binding energies, whereas the Cu 2p core levels shifted to lower binding energies, indicating alloying of the silver and copper. Rotating disk electrode measurements indicated that the oxygen reduction reaction (ORR) proceeded through a four-electron pathway on the Ag50Cu50 and Ag90Cu10 nanoalloy catalysts in alkaline solution. Moreover, the catalytic activity of Ag50Cu50 in the ORR is more efficient than that of Ag90Cu10. By performing charge and discharge cycling measurements, the Ag50Cu50 catalyst layer was confirmed to have a maximum power density of approximately 86.3 mW cm(-2) and an acceptable cell voltage at 0.863 V for current densities up to 100 mA cm(-2) in primary zinc-air batteries. In addition, a round-trip efficiency of approximately 50% at a current density of 20 mA cm(-2) was also obtained in the test. PMID:26200807

  2. Enhanced electromechanical response of Ionic Polymer-Metal Composite (IPMC) actuators by various Nafion roughening levels

    NASA Astrophysics Data System (ADS)

    Wang, Yanjie; Liu, Jiayu; Chen, Hualing

    2016-04-01

    Recently, Ionic polymer metal composites (IPMCs), becoming an increasingly popular material, are used as soft actuators for its inherent properties of light weight, flexibility, softness, especial efficient transformation from electrical energy to mechanical energy with large bending strain response to low activation voltage. This paper mainly focuses on the suitable conditions for surface-roughening of Nafion 117 membrane. The surfaces of Nafion membrane were pretreated and optimized by sandblasting, mainly considering the change of sandblasting time and powder size. The modified surfaces are characterized in terms of their topography from the confocal laser scanning microscope (CLSM) and SEM. Then, the detailed change in surface and interfacial electrodes and performances for IPMC actuators prepared by the roughened membranes, were measured and discussed. The results show that an optimized roughening condition with large interface area (capacitance) can effectively increases the electromechanical responses of IPMC.

  3. Synthesis of silver nanowires using hydrothermal technique for flexible transparent electrode application

    NASA Astrophysics Data System (ADS)

    Vijila, C. V. Mary; Rahman, K. K. Arsina; Parvathy, N. S.; Jayaraj, M. K.

    2016-05-01

    Transparent conducting films are becoming increasingly interesting because of their applications in electronics industry such as their use in solar energy applications. In this work silver nanowires were synthesized using solvothermal method by reducing silver nitrate and adding sodium chloride for assembling silver into nanowires. Absorption spectra of nanowires in the form of a dispersion in deionized water, AFM and SEM images confirm the nanowire formation. Solution of nanowire was coated over PET films to obtain transparent conducting films.

  4. Silver

    Integrated Risk Information System (IRIS)

    Silver ; CASRN 7440 - 22 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects )

  5. Silver Nanowire-IZO-Conducting Polymer Hybrids for Flexible and Transparent Conductive Electrodes for Organic Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Yun, Ho Jun; Kim, Se Jung; Hwang, Ju Hyun; Shim, Yong Sub; Jung, Sun-Gyu; Park, Young Wook; Ju, Byeong-Kwon

    2016-10-01

    Solution-processed silver nanowire (AgNW) has been considered as a promising material for next-generation flexible transparent conductive electrodes. However, despite the advantages of AgNWs, some of their intrinsic drawbacks, such as large surface roughness and poor interconnection between wires, limit their practical application in organic light-emitting diodes (OLEDs). Herein, we report a high-performance AgNW-based hybrid electrode composed of indium-doped zinc oxide (IZO) and poly (3,4-ethylenediowythiophene):poly(styrenesulfonate) [PEDOT:PSS]. The IZO layer protects the underlying AgNWs from oxidation and corrosion and tightly fuses the wires together and to the substrate. The PEDOT:PSS effectively reduces surface roughness and increases the hybrid films’ transmittance. The fabricated electrodes exhibited a low sheet resistance of 5.9 Ωsq‑1 with high transmittance of 86% at 550 nm. The optical, electrical, and mechanical properties of the AgNW-based hybrid films were investigated in detail to determine the structure-property relations, and whether optical or electrical properties could be controlled with variation in each layer’s thickness to satisfy different requirements for different applications. Flexible OLEDs (f-OLEDs) were successfully fabricated on the hybrid electrodes to prove their applicability; their performance was even better than those on commercial indium doped tin oxide (ITO) electrodes.

  6. Silver Nanowire-IZO-Conducting Polymer Hybrids for Flexible and Transparent Conductive Electrodes for Organic Light-Emitting Diodes

    PubMed Central

    Yun, Ho Jun; Kim, Se Jung; Hwang, Ju Hyun; Shim, Yong Sub; Jung, Sun-Gyu; Park, Young Wook; Ju, Byeong-Kwon

    2016-01-01

    Solution-processed silver nanowire (AgNW) has been considered as a promising material for next-generation flexible transparent conductive electrodes. However, despite the advantages of AgNWs, some of their intrinsic drawbacks, such as large surface roughness and poor interconnection between wires, limit their practical application in organic light-emitting diodes (OLEDs). Herein, we report a high-performance AgNW-based hybrid electrode composed of indium-doped zinc oxide (IZO) and poly (3,4-ethylenediowythiophene):poly(styrenesulfonate) [PEDOT:PSS]. The IZO layer protects the underlying AgNWs from oxidation and corrosion and tightly fuses the wires together and to the substrate. The PEDOT:PSS effectively reduces surface roughness and increases the hybrid films’ transmittance. The fabricated electrodes exhibited a low sheet resistance of 5.9 Ωsq−1 with high transmittance of 86% at 550 nm. The optical, electrical, and mechanical properties of the AgNW-based hybrid films were investigated in detail to determine the structure-property relations, and whether optical or electrical properties could be controlled with variation in each layer’s thickness to satisfy different requirements for different applications. Flexible OLEDs (f-OLEDs) were successfully fabricated on the hybrid electrodes to prove their applicability; their performance was even better than those on commercial indium doped tin oxide (ITO) electrodes. PMID:27703182

  7. The role of graphene formed on silver nanowire transparent conductive electrode in ultra-violet light emitting diodes.

    PubMed

    Seo, Tae Hoon; Lee, Seula; Min, Kyung Hyun; Chandramohan, S; Park, Ah Hyun; Lee, Gun Hee; Park, Min; Suh, Eun-Kyung; Kim, Myung Jong

    2016-01-01

    This paper reports a highly reliable transparent conductive electrode (TCE) that integrates silver nanowires (AgNWs) and high-quality graphene as a protecting layer. Graphene with minimized defects and large graphene domains has been successfully obtained through a facile two-step growth approach. Ultraviolet light emitting diodes (UV-LEDs) were fabricated with AgNWs or hybrid electrodes where AgNWs were combined with two-step grown graphene (A-2GE) or conventional one-step grown graphene (A-1GE). The device performance and reliability of the UV-LEDs with three different electrodes were compared. The A-2GE offered high figure of merit owing to the excellent UV transmittance and reduced sheet resistance. As a consequence, the UV-LEDs made with A-2GE demonstrated reduced forward voltage, enhanced electroluminescence (EL) intensity, and alleviated efficiency droop. The effects of joule heating and UV light illumination on the electrode stability were also studied. The present findings prove superior performance of the A-2GE under high current injection and continuous operation of UV LED, compared to other electrodes. From our observation, the A-2GE would be a reliable TCE for high power UV-LEDs. PMID:27387274

  8. The role of graphene formed on silver nanowire transparent conductive electrode in ultra-violet light emitting diodes

    NASA Astrophysics Data System (ADS)

    Seo, Tae Hoon; Lee, Seula; Min, Kyung Hyun; Chandramohan, S.; Park, Ah Hyun; Lee, Gun Hee; Park, Min; Suh, Eun-Kyung; Kim, Myung Jong

    2016-07-01

    This paper reports a highly reliable transparent conductive electrode (TCE) that integrates silver nanowires (AgNWs) and high-quality graphene as a protecting layer. Graphene with minimized defects and large graphene domains has been successfully obtained through a facile two-step growth approach. Ultraviolet light emitting diodes (UV-LEDs) were fabricated with AgNWs or hybrid electrodes where AgNWs were combined with two-step grown graphene (A-2GE) or conventional one-step grown graphene (A-1GE). The device performance and reliability of the UV-LEDs with three different electrodes were compared. The A-2GE offered high figure of merit owing to the excellent UV transmittance and reduced sheet resistance. As a consequence, the UV-LEDs made with A-2GE demonstrated reduced forward voltage, enhanced electroluminescence (EL) intensity, and alleviated efficiency droop. The effects of joule heating and UV light illumination on the electrode stability were also studied. The present findings prove superior performance of the A-2GE under high current injection and continuous operation of UV LED, compared to other electrodes. From our observation, the A-2GE would be a reliable TCE for high power UV-LEDs.

  9. Decolorization of C. I. Reactive Orange 4 and Textile Effluents by Electrochemical Oxidation Technique using Silver-Carbon Composite Electrode.

    PubMed

    Nordin, Norazzizi; Fathrita Mohd Amir, Siti; Rahimi Yusop, Muhammad; Rozali Othman, Mohamed

    2015-01-01

    In this study, the electrochemical oxidation of C. I. Reactive Orange 4 (RO4) on a silver-carbon composite (AgC-PVC) electrode was studied using the cyclic voltammetry, potential liner V, and electrolysis methods. The AgC-PVC electrode was used as the working electrode in the electrochemical measurement of RO4 in the presence of NaCl as a supporting electrolyte. The UV-Vis spectra of RO4 after the electrochemical oxidation showed the complete decolorization of the solution. The electrolysis products were characterized using FTIR and GC-MS. The results showed that in the presence of OCl- as an active oxidant, RO4 molecules are broken down into several lower-molecular-weight molecules by the electrochemical technique. The electrode used was also able to reduce the COD, BOD(5) and surfactant contents in the textile effluents using a pilot scale reactor. This proved that the prepared AgC-PVC electrode was beneficial for removing both the color and other pollutants from textile effluents. PMID:26454599

  10. The role of graphene formed on silver nanowire transparent conductive electrode in ultra-violet light emitting diodes.

    PubMed

    Seo, Tae Hoon; Lee, Seula; Min, Kyung Hyun; Chandramohan, S; Park, Ah Hyun; Lee, Gun Hee; Park, Min; Suh, Eun-Kyung; Kim, Myung Jong

    2016-07-08

    This paper reports a highly reliable transparent conductive electrode (TCE) that integrates silver nanowires (AgNWs) and high-quality graphene as a protecting layer. Graphene with minimized defects and large graphene domains has been successfully obtained through a facile two-step growth approach. Ultraviolet light emitting diodes (UV-LEDs) were fabricated with AgNWs or hybrid electrodes where AgNWs were combined with two-step grown graphene (A-2GE) or conventional one-step grown graphene (A-1GE). The device performance and reliability of the UV-LEDs with three different electrodes were compared. The A-2GE offered high figure of merit owing to the excellent UV transmittance and reduced sheet resistance. As a consequence, the UV-LEDs made with A-2GE demonstrated reduced forward voltage, enhanced electroluminescence (EL) intensity, and alleviated efficiency droop. The effects of joule heating and UV light illumination on the electrode stability were also studied. The present findings prove superior performance of the A-2GE under high current injection and continuous operation of UV LED, compared to other electrodes. From our observation, the A-2GE would be a reliable TCE for high power UV-LEDs.

  11. The role of graphene formed on silver nanowire transparent conductive electrode in ultra-violet light emitting diodes

    PubMed Central

    Seo, Tae Hoon; Lee, Seula; Min, Kyung Hyun; Chandramohan, S.; Park, Ah Hyun; Lee, Gun Hee; Park, Min; Suh, Eun-Kyung; Kim, Myung Jong

    2016-01-01

    This paper reports a highly reliable transparent conductive electrode (TCE) that integrates silver nanowires (AgNWs) and high-quality graphene as a protecting layer. Graphene with minimized defects and large graphene domains has been successfully obtained through a facile two-step growth approach. Ultraviolet light emitting diodes (UV-LEDs) were fabricated with AgNWs or hybrid electrodes where AgNWs were combined with two-step grown graphene (A-2GE) or conventional one-step grown graphene (A-1GE). The device performance and reliability of the UV-LEDs with three different electrodes were compared. The A-2GE offered high figure of merit owing to the excellent UV transmittance and reduced sheet resistance. As a consequence, the UV-LEDs made with A-2GE demonstrated reduced forward voltage, enhanced electroluminescence (EL) intensity, and alleviated efficiency droop. The effects of joule heating and UV light illumination on the electrode stability were also studied. The present findings prove superior performance of the A-2GE under high current injection and continuous operation of UV LED, compared to other electrodes. From our observation, the A-2GE would be a reliable TCE for high power UV-LEDs. PMID:27387274

  12. Electrode-nanoparticle collisions: The measurement of the sticking coefficient of silver nanoparticles on a glassy carbon electrode

    NASA Astrophysics Data System (ADS)

    Zhou, Yi-Ge; Rees, Neil V.; Compton, Richard G.

    2011-10-01

    In this communication, we combine anodic particle coulometry (APC) with anodic stripping voltammetry, to find the proportion of NP impacts that result in adsorbed NPs, using AgNPs in collision with glassy carbon electrode. Sticking coefficients are reported for AgNP radii of 14, 29, and 45 nm, measured at electrode biases ranging from OCV to -0.2 to -1.2 V (vs. Ag/AgCl). No significant systematic trends were found in either case. We suggest that this methodology may be widely applicable to measuring the sticking coefficient of any oxidisable metal nanoparticle on an electrode surface in solution.

  13. Enhancement of the electrical properties of silver nanowire transparent conductive electrodes by atomic layer deposition coating with zinc oxide.

    PubMed

    Pham, Anh-Tuan; Nguyen, Xuan-Quang; Tran, Duc-Huy; Ngoc Phan, Vu; Duong, Thanh-Tung; Nguyen, Duy-Cuong

    2016-08-19

    Transparent conductive electrodes for applications in optoelectronic devices such as solar cells and light-emitting diodes are important components and require low sheet resistance and high transmittance. Herein, we report an enhancement of the electrical properties of silver (Ag) nanowire networks by coating with zinc oxide using the atomic layer deposition technique. A strong decrease in the sheet resistance of Ag nanowires, namely from 20-40 Ω/□ to 7-15 Ω/□, was observed after coating with ZnO. Ag nanowire electrodes coated with 200-cycle ZnO by atomic layer deposition show the best quality, with a sheet resistance of 11 Ω/□ and transmittance of 75%.

  14. Enhancement of the electrical properties of silver nanowire transparent conductive electrodes by atomic layer deposition coating with zinc oxide

    NASA Astrophysics Data System (ADS)

    Pham, Anh-Tuan; Nguyen, Xuan-Quang; Tran, Duc-Huy; Phan, Vu Ngoc; Duong, Thanh-Tung; Nguyen, Duy-Cuong

    2016-08-01

    Transparent conductive electrodes for applications in optoelectronic devices such as solar cells and light-emitting diodes are important components and require low sheet resistance and high transmittance. Herein, we report an enhancement of the electrical properties of silver (Ag) nanowire networks by coating with zinc oxide using the atomic layer deposition technique. A strong decrease in the sheet resistance of Ag nanowires, namely from 20-40 Ω/□ to 7-15 Ω/□, was observed after coating with ZnO. Ag nanowire electrodes coated with 200-cycle ZnO by atomic layer deposition show the best quality, with a sheet resistance of 11 Ω/□ and transmittance of 75%.

  15. Enhancement of the electrical properties of silver nanowire transparent conductive electrodes by atomic layer deposition coating with zinc oxide

    NASA Astrophysics Data System (ADS)

    Pham, Anh-Tuan; Nguyen, Xuan-Quang; Tran, Duc-Huy; Phan, Vu Ngoc; Duong, Thanh-Tung; Nguyen, Duy-Cuong

    2016-08-01

    Transparent conductive electrodes for applications in optoelectronic devices such as solar cells and light-emitting diodes are important components and require low sheet resistance and high transmittance. Herein, we report an enhancement of the electrical properties of silver (Ag) nanowire networks by coating with zinc oxide using the atomic layer deposition technique. A strong decrease in the sheet resistance of Ag nanowires, namely from 20–40 Ω/□ to 7–15 Ω/□, was observed after coating with ZnO. Ag nanowire electrodes coated with 200-cycle ZnO by atomic layer deposition show the best quality, with a sheet resistance of 11 Ω/□ and transmittance of 75%.

  16. Enhancement of the electrical properties of silver nanowire transparent conductive electrodes by atomic layer deposition coating with zinc oxide.

    PubMed

    Pham, Anh-Tuan; Nguyen, Xuan-Quang; Tran, Duc-Huy; Ngoc Phan, Vu; Duong, Thanh-Tung; Nguyen, Duy-Cuong

    2016-08-19

    Transparent conductive electrodes for applications in optoelectronic devices such as solar cells and light-emitting diodes are important components and require low sheet resistance and high transmittance. Herein, we report an enhancement of the electrical properties of silver (Ag) nanowire networks by coating with zinc oxide using the atomic layer deposition technique. A strong decrease in the sheet resistance of Ag nanowires, namely from 20-40 Ω/□ to 7-15 Ω/□, was observed after coating with ZnO. Ag nanowire electrodes coated with 200-cycle ZnO by atomic layer deposition show the best quality, with a sheet resistance of 11 Ω/□ and transmittance of 75%. PMID:27378668

  17. Dynamic silver speciation as studied with fluorous-phase ion-selective electrodes: Effect of natural organic matter on the toxicity and speciation of silver.

    PubMed

    Mousavi, Maral P S; Gunsolus, Ian L; Pérez De Jesús, Carlos E; Lancaster, Mitchell; Hussein, Kadir; Haynes, Christy L; Bühlmann, Philippe

    2015-12-15

    The widespread application of silver in consumer products and the resulting contamination of natural environments with silver raise questions about the toxicity of Ag(+) in the ecosystem. Natural organic matter, NOM, which is abundant in water supplies, soil, and sediments, can form stable complexes with Ag(+), altering its bioavailability and toxicity. Herein, the extent and kinetics of Ag(+) binding to NOM, matrix effects on Ag(+) binding to NOM, and the effect of NOM on Ag(+) toxicity to Shewanella oneidensis MR-1 (assessed by the BacLight viability assay) were quantitatively studied with fluorous-phase Ag(+) ion-selective electrodes (ISEs). Our findings show fast kinetics of Ag(+) and NOM binding, weak Ag(+) binding for Suwannee River humic acid, fulvic acid, and aquatic NOM, and stronger Ag(+) binding for Pony Lake fulvic acid and Pahokee Peat humic acid. We quantified the effects of matrix components and pH on Ag(+) binding to NOM, showing that the extent of binding greatly depends on the environmental conditions. The effect of NOM on the toxicity of Ag(+) does not correlate with the extent of Ag(+) binding to NOM, and other forms of silver, such as Ag(+) reduced by NOM, are critical for understanding the effect of NOM on Ag(+) toxicity. This work also shows that fluorous-phase Ag(+) ISEs are effective tools for studying Ag(+) binding to NOM because they can be used in a time-resolved manner to monitor the activity of Ag(+) in situ with high selectivity and without the need for extensive sample preparation.

  18. Fabrication of silver nanowires and metal oxide composite transparent electrodes and their application in UV light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Yan, Xingzhen; Ma, Jiangang; Xu, Haiyang; Wang, Chunliang; Liu, Yichun

    2016-08-01

    In this paper, we prepared the silver nanowires (AgNWs)/aluminum-doped zinc oxide (AZO) composite transparent conducting electrodes for n-ZnO/p-GaN heterojunction light emitting-diodes (LEDs) by drop casting AgNW networks and subsequent atomic layer deposition (ALD) of AZO at 150 °C. The contact resistances between AgNWs were dramatically reduced by pre-annealing in the vacuum chamber before the ALD of AZO. In this case, AZO works not only as the conformal passivation layer that protects AgNWs from oxidation, but also as the binding material that improves AgNWs adhesion to substrates. Due to the localized surface plasmons (LSPs) of the AgNWs resonant coupling with the ultraviolet (UV) light emission from the LEDs, a higher UV light extracting efficiency is achieved from LEDs with the AgNWs/AZO composite electrodes in comparison with the conventional AZO electrodes. Additionally, the antireflective nature of random AgNW networks in the composite electrodes caused a broad output light angular distribution, which could be of benefit to certain optoelectronic devices like LEDs and solar cells.

  19. Roughening of the Pb(110) Surface

    NASA Astrophysics Data System (ADS)

    Landa, A.; Wynblatt, P.

    1996-03-01

    Large-scale molecular dynamics simulations employing a many-body (glue) potential have been used to investigate the roughening transition on the Pb(110) surface. The semi-infinite system is modeled via a slab of eight dynamical layers on top of four static substrate layers, each with 50 close-packed rows of 50 atoms. At about 350 K, the Pb(110) surface begins to disorder via the generation of vacancies and the formation of an adlayer. At about 460 K, adatoms begin to collect in clusters and the vacancies left behind aggregate into holes. The roughening transition temperature (545 K) is detected through the behavior of the interface width. At the transition temperature, the concentration of adatoms reaches 0.19. The solid-gas interface has also been mapped to the BCSOS model with energy parameters extracted from the surface excitation energies of the the glue potential. This approach yields a roughening transition temperature of about 560 K, in a good agreement with the above mentioned statistical result. The time scale of the local roughening of an initially smooth surface, at 545 K, is about 0.6 ns. Supported by the NSF under grant DMR90249776 and PSC under grant DMR930031P.

  20. From surface roughening to QCD string theory

    SciTech Connect

    Keisuke Jimmy Juge et al.

    2001-05-23

    Surface critical phenomena and the related onset of Goldstone modes represent fundamental properties of the confining flux in Quantum Chromodynamics. New ideas on surface roughening and their implications for lattice studies of quark confinement and string formation are presented. Problems with a simple string description of the large Wilson surface are discussed.

  1. Non-enzymatic amperometric detection of hydrogen peroxide in human blood serum samples using a modified silver nanowire electrode.

    PubMed

    Thirumalraj, Balamurugan; Zhao, Duo-Han; Chen, Shen-Ming; Palanisamy, Selvakumar

    2016-05-15

    In this paper, we report a highly sensitive amperometric H2O2 sensor based on silver nanowires (AgNWs) modified screen printed carbon electrode. The AgNWs were synthesized using polyol method. The synthesized AgNWs were characterized by scanning electron microscopy, UV-vis spectroscopy and X-ray diffraction techniques. The average diameter and length of the synthesized AgNWs were found as 86±5 and 385nm, respectively. Under optimum conditions, the AgNWs modified electrode shows a stable amperometric response for H2O2 and was linear over the concentrations ranging from 0.3 to 704.8μM. The non-enzymatic sensor showed a high sensitivity of 662.6μAmM(-1)cm(-2) with a detection limit of 29nM. The response time of the sensor was found as 2s. Furthermore, the AgNWs modified electrode exhibited a good recovery of H2O2 (94.3%) in the human blood serum samples.

  2. Nanoscale current spreading analysis in solution-processed graphene oxide/silver nanowire transparent electrodes via conductive atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Shaw, Joseph E.; Perumal, Ajay; Bradley, Donal D. C.; Stavrinou, Paul N.; Anthopoulos, Thomas D.

    2016-05-01

    We use conductive atomic force microscopy (CAFM) to study the origin of long-range conductivity in model transparent conductive electrodes composed of networks of reduced graphene oxide (rGOX) and silver nanowires (AgNWs), with nanoscale spatial resolution. Pristine networks of rGOX (1-3 monolayers-thick) and AgNWs exhibit sheet resistances of ˜100-1000 kΩ/□ and 100-900 Ω/□, respectively. When the materials are deposited sequentially to form bilayer rGOX/AgNW electrodes and thermally annealed at 200 °C, the sheet resistance reduces by up to 36% as compared to pristine AgNW networks. CAFM was used to analyze the current spreading in both systems in order to identify the nanoscale phenomena responsible for this effect. For rGOX networks, the low intra-flake conductivity and the inter-flake contact resistance is found to dominate the macroscopic sheet resistance, while for AgNW networks the latter is determined by the density of the inter-AgNW junctions and their associated resistance. In the case of the bilayer rGOX/AgNWs' networks, rGOX flakes are found to form conductive "bridges" between AgNWs. We show that these additional nanoscopic electrical connections are responsible for the enhanced macroscopic conductivity of the bilayer rGOX/AgNW electrodes. Finally, the critical role of thermal annealing on the formation of these nanoscopic connections is discussed.

  3. The optimization of Ag/Ag2S electrode using carrier electroplating of nano silver particles and its preliminary application to offshore Kueishan Tao, Taiwan

    NASA Astrophysics Data System (ADS)

    Ding, Qian; Pan, Yi-wen; Huang, Yuan-feng; Chen, Chen-Tung Arthur; Ye, Ying

    2015-12-01

    Eutrophication-induced ocean acidification is causing a dramatic ecologic change in the coastal ocean. A more acidic ocean would lead to more volatile H2S in the coastal ocean, especially in the area where shallow hydrothermal vents exist. Therefore, the early detection of H2S and its associates is needed. In this study, the preparation method for and the detection limit of an Ag/Ag2S electrode were optimized by coating the electrode with micro-scale to nano-scale silver particles. The size of the silver particles was dependent on the electroplating power used to produce them: (1) direct current power made micrometer scale silver particles, and (2) direct current carrier power made nano-scale silver particles. As a result, the detection limits of [S2-] of the Ag/Ag2S electrode made using direct current and direct carrier current were improved to 1×10-5 mol L-1 and 1×10-7 mol L-1, respectively. Such improvements were mostly due to the fact that nano silver particles have larger surface area and higher surface energy. The Ag/Ag2S electrode made by direct carrier current method was then mounted to a multi-parameter sensor (including a pH and an Eh electrode) used to search of new hydrothermal vents near the Kueishan Tao in May, 2011. A new hydrothermal vent was discovered based on pH, Eh and H2S anomalies at three depths. A clear [S2-] signal anomaly was observed from the top sensor indicating the dispersive pattern of the hot fluid near this shallow vent site. This could also provide additional information on the dispersion pattern of anthropogenic pollutants in the coastal ocean.

  4. Effects of surface roughening of Nafion 117 on the mechanical and physicochemical properties of ionic polymer–metal composite (IPMC) actuators

    NASA Astrophysics Data System (ADS)

    Wang, Yanjie; Zhu, Zicai; Liu, Jiayu; Chang, Longfei; Chen, Hualing

    2016-08-01

    In this paper, the surface of a Nafion membrane was roughened by the sandblasting method, mainly considering the change of sandblasting time and powder size. The roughened surfaces were characterized in terms of their topography from the confocal laser scanning microscope (CLSM) and SEM. The key surface parameters, such as Sa (the arithmetical mean deviation of the specified surface profile), SSA (the surface area ratio before and after roughening) and the area measurement on the histogram from the CLSM images, were extracted and evaluated from the roughened membranes. Also, the detailed change in surface and interfacial electrodes were measured and discussed together with the surface resistance, equivalent modulus, capacitance and performances of IPMC actuators based on the roughened membranes. The results show that a suitable sandblasting condition, resulting in the decrease in the bending stiffness and the increase in the interface area closely related to the capacitance, can effectively increase the electromechanical responses of IPMCs. Although the surface roughening by sandblasting caused a considerable lowering of mechanical strength, it was very effective for enlarging the interfacial area between Nafion membrane and the electrode layers, and for forming a penetrated electrode structure, which facilitated improvement of the surface resistance and capacitance characteristics of IPMCs. In this work, a quantitative relationship was built between the topography of Nafion membrane surface and electromechanical performance of IPMCs by means of sandblasting.

  5. Effects of surface roughening of Nafion 117 on the mechanical and physicochemical properties of ionic polymer-metal composite (IPMC) actuators

    NASA Astrophysics Data System (ADS)

    Wang, Yanjie; Zhu, Zicai; Liu, Jiayu; Chang, Longfei; Chen, Hualing

    2016-08-01

    In this paper, the surface of a Nafion membrane was roughened by the sandblasting method, mainly considering the change of sandblasting time and powder size. The roughened surfaces were characterized in terms of their topography from the confocal laser scanning microscope (CLSM) and SEM. The key surface parameters, such as Sa (the arithmetical mean deviation of the specified surface profile), SSA (the surface area ratio before and after roughening) and the area measurement on the histogram from the CLSM images, were extracted and evaluated from the roughened membranes. Also, the detailed change in surface and interfacial electrodes were measured and discussed together with the surface resistance, equivalent modulus, capacitance and performances of IPMC actuators based on the roughened membranes. The results show that a suitable sandblasting condition, resulting in the decrease in the bending stiffness and the increase in the interface area closely related to the capacitance, can effectively increase the electromechanical responses of IPMCs. Although the surface roughening by sandblasting caused a considerable lowering of mechanical strength, it was very effective for enlarging the interfacial area between Nafion membrane and the electrode layers, and for forming a penetrated electrode structure, which facilitated improvement of the surface resistance and capacitance characteristics of IPMCs. In this work, a quantitative relationship was built between the topography of Nafion membrane surface and electromechanical performance of IPMCs by means of sandblasting.

  6. The role of Cu atoms on silver electrodes in surface enhanced Raman scattering from pyridine: Giant enhancement by a minority of adsorbed molecules

    NASA Astrophysics Data System (ADS)

    Moerl, Ludwig; Pettinger, Bruno

    1982-08-01

    Surface enhanced Raman scattering (SERS) has been studied for pyridine molecules adsorbed at Ag electrodes covered with submonolayers of Cu ( θ = 0.003 - 0.1). Depending on the amount of Cu coverage the frequencies of the breathing vibrations shift, and new breathing modes appear. Obviously two types of pyridine complexes are formed, differing in the nature of the bonding provided either by copper or silver surface atoms. The generation and quenching behaviour of SERS at rough electrodes evidence the importance of metastable atomic surface structures for SERS and indicate the cooperation of local and non-local enhancement processes. Since active sites can be stabilized with traces of Cu at the silver electrode, the enhancement factor on a molecular basis appears to be by one order of magnitude larger than earlier anticipated, and ranges from 2 × 10 6 to 1.6 × 10 7 for an exciting wavelength at 514.5 nm or 647.1 nm, respectively.

  7. Spatial Competition: Roughening of an Experimental Interface.

    PubMed

    Allstadt, Andrew J; Newman, Jonathan A; Walter, Jonathan A; Korniss, G; Caraco, Thomas

    2016-01-01

    Limited dispersal distance generates spatial aggregation. Intraspecific interactions are then concentrated within clusters, and between-species interactions occur near cluster boundaries. Spread of a locally dispersing invader can become motion of an interface between the invading and resident species, and spatial competition will produce variation in the extent of invasive advance along the interface. Kinetic roughening theory offers a framework for quantifying the development of these fluctuations, which may structure the interface as a self-affine fractal, and so induce a series of temporal and spatial scaling relationships. For most clonal plants, advance should become spatially correlated along the interface, and width of the interface (where invader and resident compete directly) should increase as a power function of time. Once roughening equilibrates, interface width and the relative location of the most advanced invader should each scale with interface length. We tested these predictions by letting white clover (Trifolium repens) invade ryegrass (Lolium perenne). The spatial correlation of clover growth developed as anticipated by kinetic roughening theory, and both interface width and the most advanced invader's lead scaled with front length. However, the scaling exponents differed from those predicted by recent simulation studies, likely due to clover's growth morphology. PMID:27465518

  8. Spatial Competition: Roughening of an Experimental Interface

    PubMed Central

    Allstadt, Andrew J.; Newman, Jonathan A.; Walter, Jonathan A.; Korniss, G.; Caraco, Thomas

    2016-01-01

    Limited dispersal distance generates spatial aggregation. Intraspecific interactions are then concentrated within clusters, and between-species interactions occur near cluster boundaries. Spread of a locally dispersing invader can become motion of an interface between the invading and resident species, and spatial competition will produce variation in the extent of invasive advance along the interface. Kinetic roughening theory offers a framework for quantifying the development of these fluctuations, which may structure the interface as a self-affine fractal, and so induce a series of temporal and spatial scaling relationships. For most clonal plants, advance should become spatially correlated along the interface, and width of the interface (where invader and resident compete directly) should increase as a power function of time. Once roughening equilibrates, interface width and the relative location of the most advanced invader should each scale with interface length. We tested these predictions by letting white clover (Trifolium repens) invade ryegrass (Lolium perenne). The spatial correlation of clover growth developed as anticipated by kinetic roughening theory, and both interface width and the most advanced invader’s lead scaled with front length. However, the scaling exponents differed from those predicted by recent simulation studies, likely due to clover’s growth morphology. PMID:27465518

  9. Flexible electrochromic supercapacitor hybrid electrodes based on tungsten oxide films and silver nanowires.

    PubMed

    Shen, Liuxue; Du, Lianhuan; Tan, Shaozao; Zang, Zhigang; Zhao, Chuanxi; Mai, Wenjie

    2016-05-01

    We successfully fabricate flexible electrochromic supercapacitor (SC) electrodes employing novel flexible transparent conducting substrates. The as-synthesized flexible electrochromic SC electrodes exhibit great electrochemical performances (13.6 mF cm(-2), 138.2 F g(-1)) and high coloration efficiency (80.2 cm(2) C(-1)), which demonstrate their potential applications in flexible smart windows combining energy storage and electrochromism. PMID:27087032

  10. Annealing-free, flexible silver nanowire-polymer composite electrodes via a continuous two-step spray-coating method.

    PubMed

    Choi, Dong Yun; Kang, Hyun Wook; Sung, Hyung Jin; Kim, Sang Soo

    2013-02-01

    For the realization of high-efficiency flexible optoelectronic devices, transparent electrodes should be fabricated through a low-temperature process and have the crucial feature of low surface roughness. In this paper, we demonstrated a two-step spray-coating method for producing large-scale, smooth and flexible silver nanowire (AgNW)-poly3,4-ethylenedioxythiophene:polystyrenesulfonate (PEDOT:PSS) composite electrodes. Without the high-temperature annealing process, the conductivity of the composite film was improved via the lamination of highly conductive PEDOT:PSS modified by dimethyl sulfoxide (DMSO). Under the room temperature process condition, we fabricated the AgNW-PEDOT:PSS composite film showing an 84.3% mean optical transmittance with a 10.76 Ω sq(-1) sheet resistance. The figure of merit Φ(TC) was higher than that obtained from the indium tin oxide (ITO) films. The sheet resistance of the composite film slightly increased less than 5.3% during 200 cycles of tensile and compression folding, displaying good electromechanical flexibility for use in flexible optoelectronic applications. PMID:23241687

  11. Highly Stretchable and Conductive Silver Nanoparticle Embedded Graphene Flake Electrode Prepared by In situ Dual Reduction Reaction

    PubMed Central

    Yoon, Yeoheung; Samanta, Khokan; Lee, Hanleem; Lee, Keunsik; Tiwari, Anand P.; Lee, JiHun; Yang, Junghee; Lee, Hyoyoung

    2015-01-01

    The emergence of stretchable devices that combine with conductive properties offers new exciting opportunities for wearable applications. Here, a novel, convenient and inexpensive solution process was demonstrated to prepare in situ silver (Ag) or platinum (Pt) nanoparticles (NPs)-embedded rGO hybrid materials using formic acid duality in the presence of AgNO3 or H2PtCl6 at low temperature. The reduction duality of the formic acid can convert graphene oxide (GO) to rGO and simultaneously deposit the positively charged metal ion to metal NP on rGO while the formic acid itself is converted to a CO2 evolving gas that is eco-friendly. The AgNP-embedded rGO hybrid electrode on an elastomeric substrate exhibited superior stretchable properties including a maximum conductivity of 3012 S cm-1 (at 0 % strain) and 322.8 S cm-1 (at 35 % strain). Its fabrication process using a printing method is scalable. Surprisingly, the electrode can survive even in continuous stretching cycles. PMID:26383845

  12. Highly sensitive and selective determination of methylergometrine maleate using carbon nanofibers/silver nanoparticles composite modified carbon paste electrode.

    PubMed

    Kalambate, Pramod K; Rawool, Chaitali R; Karna, Shashi P; Srivastava, Ashwini K

    2016-12-01

    A highly sensitive and selective voltammetric method for determination of Methylergometrine maleate (MM) in pharmaceutical formulations, urine and blood serum samples has been developed based on enhanced electrochemical response of MM at carbon nanofibers and silver nanoparticles modified carbon paste electrode (CNF-AgNP-CPE). The electrode material was characterized by various techniques viz., X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The electrocatalytic response of MM at CNF-AgNP-CPE was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the proposed sensor exhibits excellent electrochemical response towards MM. The DPV study shows greatly enhanced electrochemical signal for MM at CNF-AgNP-CPE lending high sensitivity to the proposed sensor for MM detection. The peak (Ip) current for MM is found to be rectilinear in the range 4.0×10(-8)-2.0×10(-5)M with a detection limit of 7.1×10(-9)M using DPV. The feasibility of the proposed sensor in analytical applications was investigated by conducting experiments on commercial pharmaceutical formulations, human urine and blood serum samples, which yielded satisfactory recoveries of MM. The proposed electrochemical sensor offers high sensitivity, selectivity, reproducibility and practical utility. We recommend it as an authentic and productive electrochemical sensor for successful determination of MM. PMID:27612735

  13. Highly sensitive and selective determination of methylergometrine maleate using carbon nanofibers/silver nanoparticles composite modified carbon paste electrode.

    PubMed

    Kalambate, Pramod K; Rawool, Chaitali R; Karna, Shashi P; Srivastava, Ashwini K

    2016-12-01

    A highly sensitive and selective voltammetric method for determination of Methylergometrine maleate (MM) in pharmaceutical formulations, urine and blood serum samples has been developed based on enhanced electrochemical response of MM at carbon nanofibers and silver nanoparticles modified carbon paste electrode (CNF-AgNP-CPE). The electrode material was characterized by various techniques viz., X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The electrocatalytic response of MM at CNF-AgNP-CPE was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the proposed sensor exhibits excellent electrochemical response towards MM. The DPV study shows greatly enhanced electrochemical signal for MM at CNF-AgNP-CPE lending high sensitivity to the proposed sensor for MM detection. The peak (Ip) current for MM is found to be rectilinear in the range 4.0×10(-8)-2.0×10(-5)M with a detection limit of 7.1×10(-9)M using DPV. The feasibility of the proposed sensor in analytical applications was investigated by conducting experiments on commercial pharmaceutical formulations, human urine and blood serum samples, which yielded satisfactory recoveries of MM. The proposed electrochemical sensor offers high sensitivity, selectivity, reproducibility and practical utility. We recommend it as an authentic and productive electrochemical sensor for successful determination of MM.

  14. Efficient Nickel Sulfide and Graphene Counter Electrodes Decorated with Silver Nanoparticles and Application in Dye-Sensitized Solar Cells.

    PubMed

    Yue, Gentian; Li, Fumin; Yang, Guang; Zhang, Weifeng

    2016-12-01

    We reported a facile two-step electrochemical-chemical approach for in situ growth of nickel sulfide and graphene counter electrode (CE) decorated with silver nanoparticles (signed NiS/Gr-Ag) and served in dye-sensitized solar cells (DSSCs). Under optimum conditions, the DSSC achieved a remarkable power conversion efficiency of 8.36 % assembled with the NiS/Gr-Ag CE, much higher than that based on the Pt CE (7.76 %). The surface morphology of NiS/Gr-Ag CE exhibited a smooth surface with cross-growth of NiS, graphene, and Ag nanoparticles, which was beneficial to the fast mass transport of electrolytes; increased the contact area of electrolytes and active materials; and enabled to speed up the reduction of triiodide to iodide. The research on the electrochemical properties also showed that the NiS/Gr-Ag CE possessed lower charge transfer resistance and more excellent electrocatalytic activity in iodide/triiodide electrolyte compared to the Pt electrode.

  15. Efficient Nickel Sulfide and Graphene Counter Electrodes Decorated with Silver Nanoparticles and Application in Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Yue, Gentian; Li, Fumin; Yang, Guang; Zhang, Weifeng

    2016-05-01

    We reported a facile two-step electrochemical-chemical approach for in situ growth of nickel sulfide and graphene counter electrode (CE) decorated with silver nanoparticles (signed NiS/Gr-Ag) and served in dye-sensitized solar cells (DSSCs). Under optimum conditions, the DSSC achieved a remarkable power conversion efficiency of 8.36 % assembled with the NiS/Gr-Ag CE, much higher than that based on the Pt CE (7.76 %). The surface morphology of NiS/Gr-Ag CE exhibited a smooth surface with cross-growth of NiS, graphene, and Ag nanoparticles, which was beneficial to the fast mass transport of electrolytes; increased the contact area of electrolytes and active materials; and enabled to speed up the reduction of triiodide to iodide. The research on the electrochemical properties also showed that the NiS/Gr-Ag CE possessed lower charge transfer resistance and more excellent electrocatalytic activity in iodide/triiodide electrolyte compared to the Pt electrode.

  16. Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Areum; Lee, Hongseuk; Kwon, Hyeok-Chan; Jung, Hyun Suk; Park, Nam-Gyu; Jeong, Sunho; Moon, Jooho

    2016-03-01

    We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ~80% at 550 nm and sheet resistance of 18 Ω sq-1. Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process.We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ~80% at 550 nm and sheet resistance of 18 Ω sq-1. Perovskite solar cells fabricated using a fully solution

  17. Patterning Method for Silver Nanoparticle Electrodes in Fully Solution-Processed Organic Thin-Film Transistors Using Selectively Treated Hydrophilic and Hydrophobic Surfaces

    NASA Astrophysics Data System (ADS)

    Fukuda, Kenjiro; Takeda, Yasunori; Kobayashi, Yu; Shimizu, Masahiro; Sekine, Tomohito; Kumaki, Daisuke; Kurihara, Masato; Sakamoto, Masatomi; Tokito, Shizuo

    2013-05-01

    Fully solution-processed organic thin-film transistor (OTFT) devices have been fabricated with simple patterning process at a relatively low process temperature of 100 °C. In the patterning process, a hydrophobic amorphous fluoropolymer material, which was used as the gate dielectric layer and the underlying base layer, was treated with an oxygen plasma to selectively change its surface wetting properties from hydrophobic to hydrophilic. Silver source and drain electrodes were successfully formed in the treated areas with highly uniform line widths and without residues between the electrodes. Nonuniformities in the thickness of the silver electrodes originating from the “coffee-ring” effect were suppressed by optimizing the blend of solvents used with the silver nanoparticles, such that the printed electrodes are appropriate for bottom-gate OTFT devices. A fully solution-processed OTFT device using a polymer semiconductor material (PB16TTT) exhibited good electrical performance with no hysteresis in its transfer characteristics and with good linearity in its output characteristics. A relatively high carrier mobility of 0.14 cm2 V-1 s-1 and an on/off ratio of 1×105 were obtained with the fabricated TFT device.

  18. Welding of silver nanowire networks via flash white light and UV-C irradiation for highly conductive and reliable transparent electrodes

    PubMed Central

    Chung, Wan-Ho; Kim, Sang-Ho; Kim, Hak-Sung

    2016-01-01

    In this work, silver nanowire inks with hydroxypropyl methylcellulose (HPMC) binders were coated on polyethylene terephthalate (PET) substrates and welded via flash white light and ultraviolet C (UV-C) irradiation to produce highly conductive transparent electrodes. The coated silver nanowire films were firmly welded and embedded into PET substrate successfully at room temperature and under ambient conditions using an in-house flash white light welding system and UV-C irradiation. The effects of light irradiation conditions (light energy, irradiation time, pulse duration, and pulse number) on the silver nanowire networks were studied and optimized. Bending fatigue tests were also conducted to characterize the reliability of the welded transparent conductive silver nanowire films. The surfaces of the welded silver nanowire films were analyzed via scanning electron microscopy (SEM), while the transmittance of the structures was measured using a spectrophotometer. From the results, a highly conductive and transparent silver nanowire film with excellent reliability could be achieved at room temperature under ambient conditions via the combined flash white light and UV-C irradiation welding process. PMID:27553755

  19. Welding of silver nanowire networks via flash white light and UV-C irradiation for highly conductive and reliable transparent electrodes.

    PubMed

    Chung, Wan-Ho; Kim, Sang-Ho; Kim, Hak-Sung

    2016-01-01

    In this work, silver nanowire inks with hydroxypropyl methylcellulose (HPMC) binders were coated on polyethylene terephthalate (PET) substrates and welded via flash white light and ultraviolet C (UV-C) irradiation to produce highly conductive transparent electrodes. The coated silver nanowire films were firmly welded and embedded into PET substrate successfully at room temperature and under ambient conditions using an in-house flash white light welding system and UV-C irradiation. The effects of light irradiation conditions (light energy, irradiation time, pulse duration, and pulse number) on the silver nanowire networks were studied and optimized. Bending fatigue tests were also conducted to characterize the reliability of the welded transparent conductive silver nanowire films. The surfaces of the welded silver nanowire films were analyzed via scanning electron microscopy (SEM), while the transmittance of the structures was measured using a spectrophotometer. From the results, a highly conductive and transparent silver nanowire film with excellent reliability could be achieved at room temperature under ambient conditions via the combined flash white light and UV-C irradiation welding process. PMID:27553755

  20. Welding of silver nanowire networks via flash white light and UV-C irradiation for highly conductive and reliable transparent electrodes

    NASA Astrophysics Data System (ADS)

    Chung, Wan-Ho; Kim, Sang-Ho; Kim, Hak-Sung

    2016-08-01

    In this work, silver nanowire inks with hydroxypropyl methylcellulose (HPMC) binders were coated on polyethylene terephthalate (PET) substrates and welded via flash white light and ultraviolet C (UV-C) irradiation to produce highly conductive transparent electrodes. The coated silver nanowire films were firmly welded and embedded into PET substrate successfully at room temperature and under ambient conditions using an in-house flash white light welding system and UV-C irradiation. The effects of light irradiation conditions (light energy, irradiation time, pulse duration, and pulse number) on the silver nanowire networks were studied and optimized. Bending fatigue tests were also conducted to characterize the reliability of the welded transparent conductive silver nanowire films. The surfaces of the welded silver nanowire films were analyzed via scanning electron microscopy (SEM), while the transmittance of the structures was measured using a spectrophotometer. From the results, a highly conductive and transparent silver nanowire film with excellent reliability could be achieved at room temperature under ambient conditions via the combined flash white light and UV-C irradiation welding process.

  1. A silver-free, reflective substrate electrode for electron extraction in top-illuminated organic photovoltaics.

    PubMed

    Tyler, Martin S; Hutter, Oliver S; Walker, Marc; Hatton, Ross A

    2015-04-27

    The choice of metals suitable as the reflective substrate electrode for top-illuminated organic photovoltaics (OPVs) is extremely limited. Herein, we report a novel substrate electrode for this class of OPV architecture based on an Al | Cu | AlOx triple-layer structure, which offers a reflectivity comparable to that of Al over the wavelength range 400-900 nm, a work function suitable for efficient electron extraction in OPVs and high stability towards oxidation. In addition to demonstrating the advantage of this composite electrode over Al in model top-illuminated OPVs, we also present the results of a photoelectron spectroscopy study, which show that an oxidised 0.8 nm Al layer deposited by thermal evaporation onto an Al | Cu reflective substrate electrode is sufficient to block oxidation of the underlying Cu by air or during deposition of a ZnO1-x electron-transport layer. This is remarkable given that the self-limiting oxide thickness on Al metal is greater than 2 nm.

  2. Hybrid Silver Mesh Electrode for ITO-Free Flexible Polymer Solar Cells with Good Mechanical Stability.

    PubMed

    Kim, Wanjung; Kim, Soyeon; Kang, Iljoong; Jung, Myung Sun; Kim, Sung June; Kim, Jung Kyu; Cho, Sung Min; Kim, Jung-Hyun; Park, Jong Hyeok

    2016-05-10

    Herein, we report a tailored Ag mesh electrode coated with poly(3,4-ethylenedioxythiophene) (PEDOT) polymer on a flexible polyethylene terephthalate (PET) substrate. The introduction of this highly conductive polymer solves the existing problems of Ag mesh-type transparent conductive electrodes, such as high pitch, roughness, current inhomogeneity, and adhesion problems between the Ag mesh grid and PEDOT polymer or PET substrate, to result in excellent electron spreading from the discrete Ag mesh onto the entire surface without sacrificing sheet conductivity and optical transparency. Based on this hybrid anode, we demonstrate highly efficient flexible polymer solar cells (PSCs) with a high fill factor of 67.11 %, which results in a power conversion efficiency (PCE) of 6.9 % based on a poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b'] dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl) carbonyl]thieno[3,4-b]thiophenediyl}):[6,6]-phenyl-C71 -butyric acid methyl ester bulk heterojunction device. Furthermore, the PSC device with the Ag mesh electrode also exhibits a good mechanical bending stability, as indicated by a 70 % retention of the initial PCE after 500 bending cycles compared with the PSC device with a PET/indium tin oxide electrode, which retained 0 % of the initial PCE after 300 bending cycles.

  3. Effect of passivation layer on InGaZnO thin-film transistors with hybrid silver nanowires as source and drain electrodes

    NASA Astrophysics Data System (ADS)

    Yu, Chien-Hsien; Wu, Hung-Chi; Chien, Chao-Hsin

    2015-08-01

    InGaZnO (IGZO) thin-film transistors (TFTs) with hybrid silver nanowires (hybrid-AgNWs) as the source and drain electrodes exhibit superior performance according to the on/off current ratio (≈106), subthreshold swing (SS) (367 mV/decade), and mobility (15.6 cm2 V-1 s-1). The transfer and output characteristics of nanowire-based electrodes are comparable with those of titanium electrodes. The devices are fabricated on a plastic substrate and are highly transparent (>70%) and flexible. The device performance is severely degraded during operation in air, especially under high humidity conditions, and progressive deterioration resulting from water molecule diffusion leads to a high current density when the device is swept. Hence, introducing a passivation layer on the hybrid-AgNW electrodes is imperative.

  4. Surface-enhanced Raman scattering from crystal violet adsorbed on a silver electrode

    NASA Astrophysics Data System (ADS)

    Watanabe, Tadashi; Pettinger, Bruno

    1982-07-01

    SERS from crystal violet (CV) on a Ag electrode was investigated under preresonance and resonance conditions. The excitation profile of the chemisorbed species is like that of dissolved molecules but intensities are ≈ 1000 times larger. The Raman enhancement is ≈ 10 8 and exhibits a specific potential dependence even in the absence of adsorption-desorption process. At potentials where reduction of CV occurs leuco crystal violet was detected.

  5. Redox Equilibria of Cytochrome C3 Immobilised on Self-Assembled Monolayers Coated Silver Electrodes

    NASA Astrophysics Data System (ADS)

    Di Paolo, R. E.; Rivas, L.; Murgida, D.; Hildebrandt, P.

    2005-01-01

    Cytochromes c3 are soluble electron transfer proteins in the periplasm of sulphate-reducing bacteria. They act as electron-proton couplers between hydrogenase and the electron transfer chain of sulphate respiration. In this work, cytochrome c3 (Cyt-c3) obtained from both Desulfovibrio vulgaris and Desulfovibrio gigas, is electrostatically adsorbed on Ag electrodes coated with self-assembled monolayers of 11-mercaptoundecanoic acid. The redox equilibria of the adsorbed tetraheme protein are studied by surface enhanced resonance Raman spectroscopy (SERRS). The quantitative analysis of the SERR spectra, which were measured as a function of the electrode potential, allows determining the redox potentials for the individual hemes of Cyt-c3. The values obtained of the redox potentials are compared with the data provided by NMR experiments and by molecular dynamics simulation studies of the electrostatically bound protein on a coated electrode. It is found that immobilisation causes substantial shifts of the redox potential, which would have an impact on the intramolecular electron flow.

  6. Ag electrode modified with polyhexamethylene biguanide stabilized silver nanoparticles: a new type of SERS substrates for detection of enzymatically generated thiocholine

    NASA Astrophysics Data System (ADS)

    Tepanov, A. A.; Nechaeva, N. L.; Prokopkina, T. A.; Kudrinskiy, A. A.; Kurochkin, I. N.; Lisichkin, G. V.

    2015-11-01

    The detection of thiocholine is one of the most widespread techniques for estimation of the cholinesterase activity - acetylcholinesterase and butyrylcholinesterase. Both cholinesterases can be inhibited by organophosphates and carbamates and accordingly can be considered for estimation of these pollutants in the environment. In the current work, SERS spectroscopy was applied for the thiocholine detection. The Ag electrodes modified with silver nanoparticles stabilized by polyhexamethylene biguanide were for the first time suggested as SERS-substrates for that purpose. Such electrodes can be applicable for SERS detection of submicromolar concentrations of thiocholine.

  7. Healable capacitive touch screen sensors based on transparent composite electrodes comprising silver nanowires and a furan/maleimide diels-alder cycloaddition polymer.

    PubMed

    Li, Junpeng; Liang, Jiajie; Li, Lu; Ren, Fengbo; Hu, Wei; Li, Juan; Qi, Shuhua; Pei, Qibing

    2014-12-23

    A healable transparent capacitive touch screen sensor has been fabricated based on a healable silver nanowire-polymer composite electrode. The composite electrode features a layer of silver nanowire percolation network embedded into the surface layer of a polymer substrate comprising an ultrathin soldering polymer layer to confine the nanowires to the surface of a healable Diels-Alder cycloaddition copolymer and to attain low contact resistance between the nanowires. The composite electrode has a figure-of-merit sheet resistance of 18 Ω/sq with 80% transmittance at 550 nm. A surface crack cut on the conductive surface with 18 Ω is healed by heating at 100 °C, and the sheet resistance recovers to 21 Ω in 6 min. A healable touch screen sensor with an array of 8×8 capacitive sensing points is prepared by stacking two composite films patterned with 8 rows and 8 columns of coupling electrodes at 90° angle. After deliberate damage, the coupling electrodes recover touch sensing function upon heating at 80 °C for 30 s. A capacitive touch screen based on Arduino is demonstrated capable of performing quick recovery from malfunction caused by a razor blade cutting. After four cycles of cutting and healing, the sensor array remains functional.

  8. Fully Printed Halide Perovskite Light-Emitting Diodes with Silver Nanowire Electrodes.

    PubMed

    Bade, Sri Ganesh R; Li, Junqiang; Shan, Xin; Ling, Yichuan; Tian, Yu; Dilbeck, Tristan; Besara, Tiglet; Geske, Thomas; Gao, Hanwei; Ma, Biwu; Hanson, Kenneth; Siegrist, Theo; Xu, Chengying; Yu, Zhibin

    2016-02-23

    Printed organometal halide perovskite light-emitting diodes (LEDs) are reported that have indium tin oxide (ITO) or carbon nanotubes (CNTs) as the transparent anode, a printed composite film consisting of methylammonium lead tribromide (Br-Pero) and poly(ethylene oxide) (PEO) as the emissive layer, and printed silver nanowires as the cathode. The fabrication can be carried out in ambient air without humidity control. The devices on ITO/glass have a low turn-on voltage of 2.6 V, a maximum luminance intensity of 21014 cd m(-2), and a maximum external quantum efficiency (EQE) of 1.1%, surpassing previous reported perovskite LEDs. The devices on CNTs/polymer were able to be strained to 5 mm radius of curvature without affecting device properties.

  9. Fully Printed Halide Perovskite Light-Emitting Diodes with Silver Nanowire Electrodes.

    PubMed

    Bade, Sri Ganesh R; Li, Junqiang; Shan, Xin; Ling, Yichuan; Tian, Yu; Dilbeck, Tristan; Besara, Tiglet; Geske, Thomas; Gao, Hanwei; Ma, Biwu; Hanson, Kenneth; Siegrist, Theo; Xu, Chengying; Yu, Zhibin

    2016-02-23

    Printed organometal halide perovskite light-emitting diodes (LEDs) are reported that have indium tin oxide (ITO) or carbon nanotubes (CNTs) as the transparent anode, a printed composite film consisting of methylammonium lead tribromide (Br-Pero) and poly(ethylene oxide) (PEO) as the emissive layer, and printed silver nanowires as the cathode. The fabrication can be carried out in ambient air without humidity control. The devices on ITO/glass have a low turn-on voltage of 2.6 V, a maximum luminance intensity of 21014 cd m(-2), and a maximum external quantum efficiency (EQE) of 1.1%, surpassing previous reported perovskite LEDs. The devices on CNTs/polymer were able to be strained to 5 mm radius of curvature without affecting device properties. PMID:26713348

  10. Multiscale surface roughening of commercial purity titanium during uniaxial tension

    SciTech Connect

    Panin, Alexey; Kazachenok, Marina Kozelskaya, Anna Sinyakova, Elena; Lider, Andrey Sklyarova, Elena

    2015-10-27

    The mechanisms of the surface roughening of the titanium specimens during uniaxial tension were demonstrated. By means of optical profilometry and electron backscattered diffraction it was shown that the formation of surface roughening is a multilevel process. The correlation between the density of slip in some grains, and grain rotation, and their displacement towards the free surface was investigated.

  11. Composite Transparent Electrode of Graphene Nanowalls and Silver Nanowires on Micropyramidal Si for High-Efficiency Schottky Junction Solar Cells.

    PubMed

    Jiao, Tianpeng; Liu, Jian; Wei, Dapeng; Feng, Yanhui; Song, Xuefen; Shi, Haofei; Jia, Shuming; Sun, Wentao; Du, Chunlei

    2015-09-16

    The conventional graphene-silicon Schottky junction solar cell inevitably involves the graphene growth and transfer process, which results in complicated technology, loss of quality of the graphene, extra cost, and environmental unfriendliness. Moreover, the conventional transfer method is not well suited to conformationally coat graphene on a three-dimensional (3D) silicon surface. Thus, worse interfacial conditions are inevitable. In this work, we directly grow graphene nanowalls (GNWs) onto the micropyramidal silicon (MP) by the plasma-enhanced chemical vapor deposition method. By controlling growth time, the cell exhibits optimal pristine photovoltaic performance of 3.8%. Furthermore, we improve the conductivity of the GNW electrode by introducing the silver nanowire (AgNW) network, which could achieve lower sheet resistance. An efficiency of 6.6% has been obtained for the AgNWs-GNWs-MP solar cell without any chemical doping. Meanwhile, the cell exhibits excellent stability exposed to air. Our studies show a promising way to develop simple-technology, low-cost, high-efficiency, and stable Schottky junction solar cells.

  12. Anomalous kinetic roughening during anodic dissolution of polycrystalline Fe.

    PubMed

    Córdoba-Torres, P; Bastos, I N; Nogueira, R P

    2008-03-01

    Dynamics of surface roughness during polycrystalline pure iron electrodissolution is investigated at constant current density by means of ex situ atomic force microscopy. The scaling of the local surface width reveals that surface kinetic roughening is anomalous with both the exponents of local roughness, alpha(loc) , and growth, beta , close to 1 pointing out that interface evolution is unstable. We show that this anomalous unstable behavior results from the development of a faceted surface structure exposing different crystal orientations. The presence of smooth faceted walls is consistent with the value alpha(local) approximately 1 , whereas the difference in the dissolution rates on the different crystallographic planes account for the nonlocal effects causing the unstable growth. Results are discussed in the context of a recently reported anomalous scaling which accounts for dynamics of self-organized depinning models displaying faceted interfaces. The influence of the electrode potential on the dissolution rates of the different crystallographic planes, along with its effect on the mobility of metal adatoms, are discussed to be behind the complex behavior of local roughness when the current density is varied. PMID:18517390

  13. Polymer-facilitated low temperature fusing of spray-coated silver nanowire networks as transparent top and bottom electrodes in small molecule organic photovoltaics (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Selzer, Franz; Weiß, Nelli; Kneppe, David; Bormann, Ludwig; Sachse, Christoph; Gaponik, Nikolai; Eychmüller, Alexander; Leo, Karl; Müller-Meskamp, Lars

    2015-10-01

    Networks of silver nanowires (AgNWs) are promising candidates for transparent conducting electrodes in organic photovoltaics (OPV), as they achieve similar performance as the commonly used indium tin oxide (ITO) at lower cost and increased flexibility. The initial sheet resistance (Rs) of AgNW electrodes typically needs to be reduced by a post-annealing step (90 min@200 °C), being detrimental for processing on polymeric substrates. We present novel low temperature-based methods to integrate AgNWs in organic small molecule-based photovoltaics, either as transparent and highly conductive bottom-electrode or, for the first time, as spray-coated AgNW top-electrode. The bottom-electrodes are prepared by organic matrix assisted low-temperature fusing. Here, selected polymers are coated below the AgNWs to increase the interaction between NWs and substrate. In comparison to networks without these polymeric sublayers, the Rs is reduced by two orders of magnitude. AgNW top-electrodes are realized by dispersing modified high-quality AgNWs in inert solvents, which do not damage small molecule layers. Accordingly, our AgNW dispersion can be spray-coated onto all kind of OPV devices. Both bottom- and top-electrodes show a Rs of <11 Ω/ at >87 % transparency directly after spray-coating at very low substrate temperatures of <80 °C. We also demonstrate the implementation of our AgNW electrodes in organic solar cells. The corresponding devices show almost identical performance compared to organic solar cells exploiting ITO as bottom or thermally evaporated thin-metal as top-electrode.

  14. Stretchable and transparent electrodes based on patterned silver nanowires by laser-induced forward transfer for non-contacted printing techniques

    NASA Astrophysics Data System (ADS)

    Araki, Teppei; Mandamparambil, Rajesh; Martinus Peterus van Bragt, Dirk; Jiu, Jinting; Koga, Hirotaka; van den Brand, Jeroen; Sekitani, Tsuyoshi; den Toonder, Jaap M. J.; Suganuma, Katsuaki

    2016-11-01

    Silver nanowires (AgNWs) are excellent candidate electrode materials in next-generation wearable devices due to their high flexibility and high conductivity. In particular, patterning techniques for AgNWs electrode manufacture are very important in the roll-to-roll printing process to achieve high throughput and special performance production. It is also essential to realize a non-contact mode patterning for devices in order to keep the pre-patterned components away from mechanical damages. Here, we report a successful non-contact patterning of AgNWs-based stretchable and transparent electrodes by laser-induced forward transfer (LIFT) technique. The technique was used to fabricate a 100% stretchable electrode with a width of 200 μm and electrical resistivity 10‑4 Ωcm. Experiments conducted integrating the stretchable electrode on rubber substrate in which LED was pre-fabricated showed design flexibility resulting from non-contact printing. Further, a patterned transparent electrode showed over 80% in optical transmittance and less than 100 Ω sq‑1 in sheet resistance by the optimized LIFT technique.

  15. Nanoscale Chemical and Electrical Stabilities of Graphene-covered Silver Nanowire Networks for Transparent Conducting Electrodes.

    PubMed

    Kim, Seong Heon; Choi, Woon Ih; Kim, Kwang Hee; Yang, Dae Jin; Heo, Sung; Yun, Dong-Jin

    2016-01-01

    The hybrid structure of Ag nanowires (AgNWs) covered with graphene (Gr) shows synergetic effects on the performance of transparent conducting electrodes (TCEs). However, these effects have been mainly observed via large-scale characterization, and precise analysis at the nanoscale level remains inadequate. Here, we present the nanoscale verification and visualization of the improved chemical and electrical stabilities of Gr-covered AgNW networks using conductive atomic force microscopy (C-AFM), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS) combined with the gas cluster ion beam (GCIB) sputtering technique. Specifically by transferring island Gr on top of the AgNW network, we were able to create samples in which both covered and uncovered AgNWs are simultaneously accessible to various surface-characterization techniques. Furthermore, our ab initio molecular dynamics (AIMD) simulation elucidated the specific mechanistic pathway and a strong propensity for AgNW sulfidation, even in the presence of ambient oxidant gases. PMID:27620453

  16. Nanoscale Chemical and Electrical Stabilities of Graphene-covered Silver Nanowire Networks for Transparent Conducting Electrodes.

    PubMed

    Kim, Seong Heon; Choi, Woon Ih; Kim, Kwang Hee; Yang, Dae Jin; Heo, Sung; Yun, Dong-Jin

    2016-01-01

    The hybrid structure of Ag nanowires (AgNWs) covered with graphene (Gr) shows synergetic effects on the performance of transparent conducting electrodes (TCEs). However, these effects have been mainly observed via large-scale characterization, and precise analysis at the nanoscale level remains inadequate. Here, we present the nanoscale verification and visualization of the improved chemical and electrical stabilities of Gr-covered AgNW networks using conductive atomic force microscopy (C-AFM), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS) combined with the gas cluster ion beam (GCIB) sputtering technique. Specifically by transferring island Gr on top of the AgNW network, we were able to create samples in which both covered and uncovered AgNWs are simultaneously accessible to various surface-characterization techniques. Furthermore, our ab initio molecular dynamics (AIMD) simulation elucidated the specific mechanistic pathway and a strong propensity for AgNW sulfidation, even in the presence of ambient oxidant gases.

  17. Nanoscale Chemical and Electrical Stabilities of Graphene-covered Silver Nanowire Networks for Transparent Conducting Electrodes

    PubMed Central

    Kim, Seong Heon; Choi, Woon Ih; Kim, Kwang Hee; Yang, Dae Jin; Heo, Sung; Yun, Dong-Jin

    2016-01-01

    The hybrid structure of Ag nanowires (AgNWs) covered with graphene (Gr) shows synergetic effects on the performance of transparent conducting electrodes (TCEs). However, these effects have been mainly observed via large-scale characterization, and precise analysis at the nanoscale level remains inadequate. Here, we present the nanoscale verification and visualization of the improved chemical and electrical stabilities of Gr-covered AgNW networks using conductive atomic force microscopy (C-AFM), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS) combined with the gas cluster ion beam (GCIB) sputtering technique. Specifically by transferring island Gr on top of the AgNW network, we were able to create samples in which both covered and uncovered AgNWs are simultaneously accessible to various surface-characterization techniques. Furthermore, our ab initio molecular dynamics (AIMD) simulation elucidated the specific mechanistic pathway and a strong propensity for AgNW sulfidation, even in the presence of ambient oxidant gases. PMID:27620453

  18. Nanoscale Chemical and Electrical Stabilities of Graphene-covered Silver Nanowire Networks for Transparent Conducting Electrodes

    NASA Astrophysics Data System (ADS)

    Kim, Seong Heon; Choi, Woon Ih; Kim, Kwang Hee; Yang, Dae Jin; Heo, Sung; Yun, Dong-Jin

    2016-09-01

    The hybrid structure of Ag nanowires (AgNWs) covered with graphene (Gr) shows synergetic effects on the performance of transparent conducting electrodes (TCEs). However, these effects have been mainly observed via large-scale characterization, and precise analysis at the nanoscale level remains inadequate. Here, we present the nanoscale verification and visualization of the improved chemical and electrical stabilities of Gr-covered AgNW networks using conductive atomic force microscopy (C-AFM), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS) combined with the gas cluster ion beam (GCIB) sputtering technique. Specifically by transferring island Gr on top of the AgNW network, we were able to create samples in which both covered and uncovered AgNWs are simultaneously accessible to various surface-characterization techniques. Furthermore, our ab initio molecular dynamics (AIMD) simulation elucidated the specific mechanistic pathway and a strong propensity for AgNW sulfidation, even in the presence of ambient oxidant gases.

  19. Organic-Stabilizer-Free Polyol Synthesis of Silver Nanowires for Electrode Applications.

    PubMed

    Sim, Hwansu; Bok, Shingyu; Kim, Bongsung; Kim, Minha; Lim, Guh-Hwan; Cho, Sung Min; Lim, Byungkwon

    2016-09-19

    The polyol reduction of a Ag precursor in the presence of an organic stabilizer, such as poly(vinylpyrrolidone), is a widely used method for the production of Ag nanowires (NWs). However, organic capping molecules introduce insulating layers around each NW. Herein we demonstrate that Ag NWs can be produced in high yield without any organic stabilizers simply by introducing trace amounts of NaCl and Fe(NO3 )3 during low-temperature polyol synthesis. The heterogeneous nucleation and growth of Ag NWs on initially formed AgCl particles, combined with oxidative etching of unwanted Ag nanoparticles, resulted in the selective formation of long NWs with an average length of about 40 μm in the absence of a capping or stabilizing effect provided by surface-adsorbing molecules. These organic-stabilizer-free Ag NWs were directly used for the fabrication of high-performance transparent or stretchable electrodes without a complicated process for the removal of capping molecules from the NW surface. PMID:27571578

  20. Organic-Stabilizer-Free Polyol Synthesis of Silver Nanowires for Electrode Applications.

    PubMed

    Sim, Hwansu; Bok, Shingyu; Kim, Bongsung; Kim, Minha; Lim, Guh-Hwan; Cho, Sung Min; Lim, Byungkwon

    2016-09-19

    The polyol reduction of a Ag precursor in the presence of an organic stabilizer, such as poly(vinylpyrrolidone), is a widely used method for the production of Ag nanowires (NWs). However, organic capping molecules introduce insulating layers around each NW. Herein we demonstrate that Ag NWs can be produced in high yield without any organic stabilizers simply by introducing trace amounts of NaCl and Fe(NO3 )3 during low-temperature polyol synthesis. The heterogeneous nucleation and growth of Ag NWs on initially formed AgCl particles, combined with oxidative etching of unwanted Ag nanoparticles, resulted in the selective formation of long NWs with an average length of about 40 μm in the absence of a capping or stabilizing effect provided by surface-adsorbing molecules. These organic-stabilizer-free Ag NWs were directly used for the fabrication of high-performance transparent or stretchable electrodes without a complicated process for the removal of capping molecules from the NW surface.

  1. In situ surface extended x-ray absorption fine structure spectroscopy of a lead monolayer at a silver(111) electrode/electrolyte interface

    SciTech Connect

    Samant, M.G.; Borges, G.L.; Gordon J.G. II; Melroy, O.R.; Blum, L.

    1987-09-30

    With use of fluorescence detection and grazing incidence excitation, the X-ray absorption spectrum was obtained, at the PbL/sub III/ edge, of a monoatomic adlayer of lead on a silver (111) electrode immersed in solution. The adlayer was produced by under potential deposition from aqueous lead acetate/sodium acetate electrolyte. The edge position and the near-edge structure confirm that the lead is fully reduced to the zerovalent state. The extended X-ray absorption fine structure (EXAFS) contains no detectable contribution from lead-silver scattering, either because the lead layer is incommensurate with the underlying silver lattice or because there is large thermal motion of the lead atoms. Instead, the fine structure is due to scattering from a single type of light atom, most likely oxygen. This oxygen must arise from adsorbed water molecules or acetate ions. The lead-oxygen distance changes with the electrode potential from 2.33 +/- 0.02 A at -0.53 V to 2.38 +/- 0.02 A at -1 V (vs. Ag/AgCl, 3 M KCl).

  2. Self-similar roughening of drying wet paper.

    PubMed

    Balankin, Alexander S; Morales, Daniel; Susarrey, Orlando; Samayoa, Didier; Trinidad, José Martinez; Marquez, Jesús; García, Rafael

    2006-06-01

    We studied the kinetic roughening dynamics of drying wet paper. The configurations of dry paper sheets are found to be self-similar, rater than self-affine. Accordingly, the paper roughening dynamics corresponds to the new class of anomalous kinetic roughening [J. J. Ramasco, J. M. López, and M. A. Rodríguez, Phys. Rev. Lett. 84, 2199 (2000)], characterized by the equal local and global roughness exponents zeta = alpha = 1 and the dynamic exponent z = 1.0+/-0.2, whereas the spectral roughness exponent alpha(s) > 1 is determined by the long-range correlations characterized by the fractal dimension of D crumpled sheet.

  3. Oxidation-reduction induced roughening of platinum (111) surface

    SciTech Connect

    You, H.; Nagy, Z.

    1993-06-01

    Platinum (111) single crystal surface was roughened by repeated cycles of oxidation and reduction to study dynamic evolution of surface roughening. The interface roughens progressively upon repeated cycles. The measured width of the interface was fit to an assumed pow law, W {approximately}t{sup {beta}}, with {beta} = 0.38(1). The results are compared with a simulation based on a random growth model. The fraction of the singly stepped surface apparently saturates to 0. 25 monolayer, which explains the apparent saturation to a steady roughness observed in previous studies.

  4. Roughening of Polyimide Surface for Inkjet Printing by Plasma Etching Using the Polyimide Masked with Polystyrene Nanosphere Array.

    PubMed

    Mun, Mu Kyeom; Park, Jin Woo; Ahn, Jin Ho; Kim, Ki Kang; Yeom, Geun Young

    2015-10-01

    Two key conditions are required for the application of fine-line inkjet printing onto a flexible substrate such as polyimide (PI): linewidth control during the inkjetting process, and a strong adhesion of the polyimide surface to the ink after the ink solidifies. In this study, the properties of a polyimide surface that was roughened through etching in a He/SF6 plasma, using a polystyrene nanosphere array as the etch mask, were investigated. The near-atmospheric-pressure plasma system of the He/SF6 plasma that was used exhibits two notable properties in this context: similar to an atmospheric-pressure plasma system, it can easily handle inline substrate processing; and, similar to a vacuum system, it can control the process gas environment. Through the use of plasma etching, the polyimide surface masked the 120-nm-diameter polystyrene nanospheres, thereby forming a roughened nanoscale polyimide surface. This surface exhibited not only a greater hydrophobicity--with a contact angle of about 150° for water and about 30° for silver ink, indicating better silver linewidth control during the silver inkjetting process--but also a stronger adhesion to the silver ink sprayed onto it when compared with the flat polyimide surface. PMID:26726483

  5. Electrochemical Investigation of Coenzyme Q10 on Silver Electrode in Ethanol Aqueous Solution and Its Determination Using Differential Pulse Voltammetry.

    PubMed

    Li, Dan; Deng, Wei; Xu, Hu; Sun, Yinxing; Wang, Yuhong; Chen, Shouhui; Ding, Xianting

    2016-08-01

    The electrochemistry reduction of coenzyme Q10 (CoQ10) on silver electrodes has been investigated in mixed solvent containing 95 vol. % ethanol and 5 vol. % water. A combination of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) is employed to explore the mechanism of redox processes of CoQ10 in the presence and absence of oxygen, respectively. It has been proved that the redox reaction of CoQ10 is highly dependent on the oxygen in the solution compared with that of CoQ0, which may be attributed to the isoprenoid side chain effect of CoQ10 Moreover, the effects of experimental variables such as electrolyte component, pH, temperature, and sonication time on the amperometric and potentiometric responses of CoQ10 are presented. The differential pulse voltammetry method has been developed for the quantification of the CoQ10 in the complex samples. Under the optimum conditions, the method is linear over the concentration range of 1.00 × 10(-7) to 1.00 × 10(-3) mol/L (8.63 × 10(-2) to 8.63 × 10(2) mg/kg). The limit of detection (3σ/k) is 3.33 × 10(-8) mol/L (2.88 × 10(-2) mg/kg). The recoveries of the spiked samples are between 91% and 108%. The presented method can be applied to the analysis of CoQ10 in real samples without any pretreatment.

  6. Effects of surface roughening on the mass transport and mechanical properties of ionic polymer-metal composite

    NASA Astrophysics Data System (ADS)

    Chang, Longfei; Asaka, Kinji; Zhu, Zicai; Wang, Yanjie; Chen, Hualing; Li, Dichen

    2014-06-01

    Ionic Polymer-Metal Composite (IPMC) has been well-documented of being a promising functional material in extensive applications. In its most popular and traditional manufacturing technique, roughening is a key process to ensure a satisfying performance. In this paper, based on a lately established multi-physical model, the effect of roughening process on the inner mass transportation and the electro-active output of IPMC were investigated. In the model, the electro-chemical field was monitored by Poisson equation and a properly simplified Nernst-Planck equation set, while the mechanical field was evaluated on the basis of volume strain effect. Furthermore, with Ramo-Shockley theorem, the out-circuit current and accumulated charge on the electrode were bridged with the inner cation distribution. Besides, nominal current and charge density as well as the curvature of the deformation were evaluated to characterize the performance of IPMC. The simulation was implemented by Finite Element Method with Comsol Multi-physics, based on two groups of geometrical models, those with various rough interface and those with different thickness. The results of how the roughening impact influences on the performance of IPMC were discussed progressively in three aspects, steady-state distribution of local potential and mass concentration, current response and charge accumulation, as well as the curvature of deformation. Detailed explanations for the performance improvement resulted from surface roughening were provided from the micro-distribution point of view, which can be further explored for the process optimization of IPMC.

  7. Determination of ultra-trace amounts of silver in water by differential pulse anodic stripping voltammetry using a new modified carbon paste electrode.

    PubMed

    El-Mai, Hafida; Espada-Bellido, Estrella; Stitou, Mostafa; García-Vargas, Manuel; Galindo-Riaño, Maria Dolores

    2016-05-01

    A highly sensitive and selective new procedure for the determination of silver in aqueous media was developed using a modified carbon paste electrode (MCPE) by differential pulse anodic stripping voltammetry (DPASV). The modified electrode was based on the incorporation of 2-hydroxybenzaldehyde benzoylhydrazone (2-HBBH) in the carbon paste electrode. Silver ions were preconcentrated on the modified electrode at open-circuit by complexation with the ligand and reduced to zero valent at a potential of 0V, and followed by the reoxidation of adsorbed ions onto the electrode by scanning the potential in a positive direction. The oxidation peak of Ag(I) was observed at 0.2V (versus Ag/AgCl). The analysis of Ag(I) was carried out in a cell containing the sample solution (20mL) buffered by 0.1molL(-1) K2HPO4/NaOH at pH 5.5 in aqueous solution and nitric acid (pH 1) in real water samples. The optimum conditions for the analysis of silver include a reduction potential of 0V and a pulse amplitude of 100mV, among others. The optimum carbon paste composition was found to be 14.1% (w/w) 2-HBBH, 56.2% (w/w) graphite powder and 29.7% (w/w) paraffin oil. Differential pulse anodic stripping voltammetric response was used as the analytical signal. Under the selected conditions, the voltammetric signal was proportional to the Ag(I) concentration in the range of 0.001-100μgL(-1) with favorable limits of detection and quantification of 1.1ngL(-1) and 3.7ngL(-1) after 3min of accumulation time, respectively. By increasing the accumulation time to 10min, detection and quantification limits can be further improved up to 0.1ngL(-1) and 0.34ngL(-1), respectively. In addition, the results showed a highly reproducible procedure showing a relative standard deviation of 1.5% for 12 replicate measurements. Many coexisting metal ions were investigated and very few interferences were found on the determination of Ag(I). The proposed method was validated using certified reference estuarine waters

  8. Silver composite cathodes for alkaline secondary batteries

    NASA Astrophysics Data System (ADS)

    Ferrando, William A.

    1989-08-01

    This invention relates to electrochemical cells and more particularly to silver electrodes for electrochemical cells. Accordingly, an object of this invention is to provide a new, lighter weight silver electrode for secondary cells. Another object of this invention is to provide an electrode which requires less silver to operate. A further object of this invention is to provide a silver electrode which uses the silver more efficiently. Yet another object of the invention is to provide an easier, less expensive method of manufacturing silver electrodes for secondary cells.

  9. Bioinspired assembly of surface-roughened nanoplatelets.

    PubMed

    Lin, Tzung-Hua; Huang, Wei-Han; Jun, In-Kook; Jiang, Peng

    2010-04-15

    Here we report a novel electrophoretic deposition technology for assembling surface-roughened inorganic nanoplatelets into ordered multilayers that mimic the brick-and-mortar nanostructure found in the nacreous layer of mollusk shells. A thin layer of sol-gel silica is coated on smooth gibbsite nanoplatelets in order to increase the surface roughness to mimic the asperity of aragonite platelets found in nacres. To avoid the severe cracking caused by the shrinkage of sol-gel silica during drying, polyelectrolyte polyethyleneimine is used to reverse the surface charge of silica-coated-gibbsite nanoplatelets and increase the adherence and strength of the electrodeposited films. Polymer nanocomposites can then be made by infiltrating the interstitials of the aligned nanoplatelet multilayers with photocurable monomer followed by photopolymerization. The resulting self-standing films are highly transparent and exhibit nearly three times higher tensile strength and one-order-of-magnitude higher toughness than those of pure polymer. The measured tensile strength agrees with that predicted by a simple shear lag model. PMID:20102769

  10. Surface roughened zirconia: towards hydrothermal stability.

    PubMed

    Camposilvan, Erik; Flamant, Quentin; Anglada, Marc

    2015-07-01

    Surface roughness is needed in several yttria-stabilized zirconia components used in restorative dentistry for osseointegration or adhesion purposes. This can be achieved by different treatments, which may also modify the microstructure of the surface. Among them, sandblasting and chemical etching are widely used, but their effect on hydrothermal aging of zirconia is not fully understood. In the present work, the zirconia long-term stability of rough surfaces prepared by these techniques is analyzed and a method is proposed for preventing hydrothermal aging while maintaining the original surface appearance and mechanical properties. The method involves pressure infiltration of a Cerium salt solution on the roughened surfaces followed by a thermal treatment. The solution, trapped by surface defects and small pores, is decomposed during thermal treatment into Cerium oxide, which is diffused at high temperature, obtaining Ce co-doping in the near-surface region. In addition, the microstructural changes induced in the near-surface by sandblasting or chemical etching are removed by the thermal treatment together with surface defects. No color modification was observed and the final roughness parameters were in the range of existing implants of proved good osseointegration. The aging resistance of Ce co-doped materials was strongly enhanced, showing the absence of aging after artificial degradation, increasing in this way the surface mechanical integrity. The proposed treatment is easily applicable to the current manufacturing procedures of zirconia dental posts, abutments, crowns and dentures, representing a solution to hydrothermal aging in these and other biomedical applications.

  11. Reproducible preparation of a stable polypyrrole-coated-silver nanoparticles decorated polypyrrole-coated-polycaprolactone-nanofiber-based cloth electrode for electrochemical sensor application.

    PubMed

    Li, Li; Wang, Xiaoping; Liu, Guiting; Wang, Zhenzhen; Wang, Feng; Guo, Xiaoyu; Wen, Ying; Yang, Haifeng

    2015-11-01

    A piece of conductive cloth has been successfully constructed from polypyrrole-coated silver nanoparticle (Ag@PPy) composites decorated on electrospun polycaprolactone (PCL) nanofibers that formed the core-shell structure of Ag@PPy/PCL@PPy via a photo-induced one-step redox reaction. The photochemical reaction method both accelerated the rate of formation of silver nanoparticles (Ag NPs) and enhanced the dispersion of Ag NPs at the surface of PCL@PPy film. The resulting Ag@PPy/PCL@PPy-based cloth was flexible enough to be cut and pasted onto a glass carbon electrode for the preparation of a biosensor. The resulting biosensor showed good electrochemical activity toward the reduction of H2O2 with low detection limit down to 1 μM (S/N = 3) and wide linear detection ranging from 0.01 mM to 3.5 mM (R(2) = 0.990). This sensor has been applied to detect the trace H2O2 residual in milk. The cloth electrode has been proved to exhibit long-term stability, high selectivity, and excellent reproducibility. PMID:26469539

  12. Reproducible preparation of a stable polypyrrole-coated-silver nanoparticles decorated polypyrrole-coated-polycaprolactone-nanofiber-based cloth electrode for electrochemical sensor application

    NASA Astrophysics Data System (ADS)

    Li, Li; Wang, Xiaoping; Liu, Guiting; Wang, Zhenzhen; Wang, Feng; Guo, Xiaoyu; Wen, Ying; Yang, Haifeng

    2015-11-01

    A piece of conductive cloth has been successfully constructed from polypyrrole-coated silver nanoparticle (Ag@PPy) composites decorated on electrospun polycaprolactone (PCL) nanofibers that formed the core-shell structure of Ag@PPy/PCL@PPy via a photo-induced one-step redox reaction. The photochemical reaction method both accelerated the rate of formation of silver nanoparticles (Ag NPs) and enhanced the dispersion of Ag NPs at the surface of PCL@PPy film. The resulting Ag@PPy/PCL@PPy-based cloth was flexible enough to be cut and pasted onto a glass carbon electrode for the preparation of a biosensor. The resulting biosensor showed good electrochemical activity toward the reduction of H2O2 with low detection limit down to 1 μM (S/N = 3) and wide linear detection ranging from 0.01 mM to 3.5 mM (R2 = 0.990). This sensor has been applied to detect the trace H2O2 residual in milk. The cloth electrode has been proved to exhibit long-term stability, high selectivity, and excellent reproducibility.

  13. Capillary flow of solder on chemically roughened PWB surfaces

    SciTech Connect

    Hosking, F.M.; Stevenson, J.O.; Yost, F.G.

    1996-02-01

    The Center for Solder Science and Technology at Sandia National Laboratories has developed a solderability test for evaluating fundamental solder flow over PWB (printed wiring boards) surface finishes. The work supports a cooperative research and development agreement between Sandia, the National Center for Manufacturing Sciences (NCMS), and several industrial partners. An important facet of the effort involved the ``engineering`` of copper surfaces through mechanical and chemical roughening. The roughened topography enhances solder flow, especially over very fine features. In this paper, we describe how etching with different chemical solutions can affect solder flow on a specially designed ball grid array test vehicle (BGATV). The effects of circuit geometry, solution concentration, and etching time are discussed. Surface roughness and solder flow data are presented to support the roughening premise. Noticeable improvements in solder wettability were observed on uniformly etched surfaces having relatively steep peak-to-valley slopes.

  14. Ultrasensitive detection of lead ion sensor based on gold nanodendrites modified electrode and electrochemiluminescent quenching of quantum dots by electrocatalytic silver/zinc oxide coupled structures.

    PubMed

    Li, Meng; Kong, Qingkun; Bian, Zhaoquan; Ma, Chao; Ge, Shenguang; Zhang, Yan; Yu, Jinghua; Yan, Mei

    2015-03-15

    A signal-off electrochemiluminescence (ECL) DNA sensor based on gold nanodendrites (Au NDs) modified indium tin oxide (ITO) electrode for the detection of lead ion (Pb(2+)) was developed. Well-defined Au NDs were prepared on ITO electrode using low-potential synthesis, assisted by ethylenediamine. Based on Pb(2+)-specific deoxyribozyme, the silver/zinc oxide (Ag/ZnO) with coupled structure, prepared by one-pot method, was close to the surface of the electrode to catalyze the reduction of part of H2O2, the coreactant for cathodic ECL emission, leading to a decrease of ECL intensity. In addition, taking advantage of the larger surface area to capture a large amount of capture probe as well as excellent conductivity of Au NDs, the sensor could detect Pb(2+) quantitatively in a wider range, and performed excellent selectivity. Furthermore, such simple and sensitive DNA sensor was successfully applied for the detection of Pb(2+) in lake water and human serum samples, respectively. PMID:25461155

  15. Ultrasensitive detection of lead ion sensor based on gold nanodendrites modified electrode and electrochemiluminescent quenching of quantum dots by electrocatalytic silver/zinc oxide coupled structures.

    PubMed

    Li, Meng; Kong, Qingkun; Bian, Zhaoquan; Ma, Chao; Ge, Shenguang; Zhang, Yan; Yu, Jinghua; Yan, Mei

    2015-03-15

    A signal-off electrochemiluminescence (ECL) DNA sensor based on gold nanodendrites (Au NDs) modified indium tin oxide (ITO) electrode for the detection of lead ion (Pb(2+)) was developed. Well-defined Au NDs were prepared on ITO electrode using low-potential synthesis, assisted by ethylenediamine. Based on Pb(2+)-specific deoxyribozyme, the silver/zinc oxide (Ag/ZnO) with coupled structure, prepared by one-pot method, was close to the surface of the electrode to catalyze the reduction of part of H2O2, the coreactant for cathodic ECL emission, leading to a decrease of ECL intensity. In addition, taking advantage of the larger surface area to capture a large amount of capture probe as well as excellent conductivity of Au NDs, the sensor could detect Pb(2+) quantitatively in a wider range, and performed excellent selectivity. Furthermore, such simple and sensitive DNA sensor was successfully applied for the detection of Pb(2+) in lake water and human serum samples, respectively.

  16. Investigation of protein FTT1103 electroactivity using carbon and mercury electrodes. Surface-inhibition approach for disulfide oxidoreductases using silver amalgam powder.

    PubMed

    Večerková, Renata; Hernychová, Lenka; Dobeš, Petr; Vrba, Jiří; Josypčuk, Bohdan; Bartošík, Martin; Vacek, Jan

    2014-06-01

    Recently, it was shown that electrochemical methods can be used for analysis of poorly water-soluble proteins and for study of their structural changes and intermolecular (protein-ligand) interactions. In this study, we focused on complex electrochemical investigation of recombinant protein FTT1103, a disulfide oxidoreductase with structural similarity to well described DsbA proteins. This thioredoxin-like periplasmic lipoprotein plays an important role in virulence of bacteria Francisella tularensis. For electrochemical analyses, adsorptive transfer (ex situ) square-wave voltammetry with pyrolytic graphite electrode, and alternating-current voltammetry and constant-current chronopotentiometric stripping analysis with mercury electrodes, including silver solid amalgam electrode (AgSAE) were used. AgSAE was used in poorly water-soluble protein analysis for the first time. In addition to basic redox, electrocatalytic and adsorption/desorption characterization of FTT1103, electrochemical methods were also used for sensitive determination of the protein at nanomolar level and study of its interaction with surface of AgSA microparticles. Proposed electrochemical protocol and AgSA surface-inhibition approach presented here could be used in future for biochemical studies focused on proteins associated with membranes as well as on those with disulfide oxidoreductase activity.

  17. A spray-coating process for highly conductive silver nanowire networks as the transparent top-electrode for small molecule organic photovoltaics.

    PubMed

    Selzer, Franz; Weiss, Nelli; Kneppe, David; Bormann, Ludwig; Sachse, Christoph; Gaponik, Nikolai; Eychmüller, Alexander; Leo, Karl; Müller-Meskamp, Lars

    2015-02-14

    We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 Ω □(-1) at 87.4% transparency (80.0% with substrate). By spraying our novel AgNW dispersion in air onto the vacuum-processed organic p-i-n type solar cells, we obtain working solar cells with a power conversion efficiency (PCE) of 1.23%, compared to the air exposed reference devices employing thermally evaporated thin metal layers as the top-electrode.

  18. Amperometric detection and electrochemical oxidation of aliphatic amines and ammonia on silver-lead oxide thin-film electrodes

    SciTech Connect

    Ge, Jisheng

    1996-01-08

    This thesis comprises three parts: Electrocatalysis of anodic oxygen-transfer reactions: aliphatic amines at mixed Ag-Pb oxide thin-film electrodes; oxidation of ammonia at anodized Ag-Pb eutectic alloy electrodes; and temperature effects on oxidation of ethylamine, alanine, and aquated ammonia.

  19. A novel paper-based device coupled with a silver nanoparticle-modified boron-doped diamond electrode for cholesterol detection.

    PubMed

    Nantaphol, Siriwan; Chailapakul, Orawon; Siangproh, Weena

    2015-09-01

    A novel paper-based analytical device (PAD) coupled with a silver nanoparticle-modified boron-doped diamond (AgNP/BDD) electrode was first developed as a cholesterol sensor. The AgNP/BDD electrode was used as working electrode after modification by AgNPs using an electrodeposition method. Wax printing was used to define the hydrophilic and hydrophobic areas on filter paper, and then counter and reference electrodes were fabricated on the hydrophilic area by screen-printing in house. For the amperometric detection, cholesterol and cholesterol oxidase (ChOx) were directly drop-cast onto the hydrophilic area, and H2O2 produced from the enzymatic reaction was monitored. The fabricated device demonstrated a good linearity (0.39 mg dL(-1) to 270.69 mg dL(-1)), low detection limit (0.25 mg dL(-1)), and high sensitivity (49.61 μA mM(-1) cm(-2)). The precision value for ten replicates was 3.76% RSD for 1 mM H2O2. In addition, this biosensor exhibited very high selectivity for cholesterol detection and excellent recoveries for bovine serum analysis (in the range of 99.6-100.8%). The results showed that this new sensing platform will be an alternative tool for cholesterol detection in routine diagnosis and offers the advantages of low sample/reagent consumption, low cost, portability, and short analysis time. PMID:26388372

  20. A novel paper-based device coupled with a silver nanoparticle-modified boron-doped diamond electrode for cholesterol detection.

    PubMed

    Nantaphol, Siriwan; Chailapakul, Orawon; Siangproh, Weena

    2015-09-01

    A novel paper-based analytical device (PAD) coupled with a silver nanoparticle-modified boron-doped diamond (AgNP/BDD) electrode was first developed as a cholesterol sensor. The AgNP/BDD electrode was used as working electrode after modification by AgNPs using an electrodeposition method. Wax printing was used to define the hydrophilic and hydrophobic areas on filter paper, and then counter and reference electrodes were fabricated on the hydrophilic area by screen-printing in house. For the amperometric detection, cholesterol and cholesterol oxidase (ChOx) were directly drop-cast onto the hydrophilic area, and H2O2 produced from the enzymatic reaction was monitored. The fabricated device demonstrated a good linearity (0.39 mg dL(-1) to 270.69 mg dL(-1)), low detection limit (0.25 mg dL(-1)), and high sensitivity (49.61 μA mM(-1) cm(-2)). The precision value for ten replicates was 3.76% RSD for 1 mM H2O2. In addition, this biosensor exhibited very high selectivity for cholesterol detection and excellent recoveries for bovine serum analysis (in the range of 99.6-100.8%). The results showed that this new sensing platform will be an alternative tool for cholesterol detection in routine diagnosis and offers the advantages of low sample/reagent consumption, low cost, portability, and short analysis time.

  1. Roughening of porous SiCOH materials in fluorocarbon plasmas

    NASA Astrophysics Data System (ADS)

    Bailly, F.; David, T.; Chevolleau, T.; Darnon, M.; Posseme, N.; Bouyssou, R.; Ducote, J.; Joubert, O.; Cardinaud, C.

    2010-07-01

    Porous SiCOH materials integration for integrated circuits faces serious challenges such as roughening during the etch process. In this study, atomic force microscopy is used to investigate the kinetics of SiCOH materials roughening when they are etched in fluorocarbon plasmas. We show that the root mean square roughness and the correlation length linearly increase with the etched depth, after an initiation period. We propose that: (1) during the first few seconds of the etch process, the surface of porous SiCOH materials gets denser. (2) Cracks are formed, leading to the formation of deep and narrow pits. (3) Plasma radicals diffuse through those pits and the pore network and modify the porous material at the bottom of the pits. (4) The difference in material density and composition between the surface and the bottom of the pits leads to a difference in etch rate and an amplification of the roughness. In addition to this intrinsic roughening mechanism, the presence of a metallic mask (titanium nitride) can lead to an extrinsic roughening mechanism, such as micromasking caused by metallic particles originating form the titanium nitride mask.

  2. A dielectrophoretic chip with a roughened metal surface for on-chip surface-enhanced Raman scattering analysis of bacteria

    PubMed Central

    Cheng, I-Fang; Lin, Chi-Chang; Lin, Dong-Yi; Chang, Hsien-Chang

    2010-01-01

    We present an analysis of the results of in situ surface-enhanced Raman scattering (SERS) of bacteria using a microfluidic chip capable of continuously sorting and concentrating bacteria via three-dimensional dielectrophoresis (DEP). Microchannels were made by sandwiching DEP microelectrodes between two glass slides. Avoiding the use of a metal nanoparticle suspension, a roughened metal surface is integrated into the DEP-based microfluidic chip for on-chip SERS detection of bacteria. On the upper surface of the slide, a roughened metal shelter was settled in front of the DEP concentrator to enhance Raman scattering. Similarly, an electrode-patterned bottom layer fabricated on a thin cover-slip was used to reduce fluorescence noise from the glass substrate. Gram positive (Staphylococcus aureus) and Gram negative (Pseudomonas aeruginosa) bacteria were effectively distinguished in the SERS spectral data. Staphylococcus aureus (concentration of 106 CFU∕ml) was continuously separated and concentrated via DEP out of a sample of blood cells. At a flow rate of 1 μl∕min, the bacteria were highly concentrated at the roughened surface and ready for on-chip SERS analysis within 3 min. The SERS data were successfully amplified by one order of magnitude and analyzed within a few minutes, resulting in the detection of signature peaks of the respective bacteria. PMID:20806000

  3. Silver front electrode grids for ITO-free all printed polymer solar cells with embedded and raised topographies, prepared by thermal imprint, flexographic and inkjet roll-to-roll processes.

    PubMed

    Yu, Jong-Su; Kim, Inyoung; Kim, Jung-Su; Jo, Jeongdai; Larsen-Olsen, Thue T; Søndergaard, Roar R; Hösel, Markus; Angmo, Dechan; Jørgensen, Mikkel; Krebs, Frederik C

    2012-09-28

    Semitransparent front electrodes for polymer solar cells, that are printable and roll-to-roll processable under ambient conditions using different approaches, are explored in this report. The excellent smoothness of indium-tin-oxide (ITO) electrodes has traditionally been believed to be difficult to achieve using printed front grids, as surface topographies accumulate when processing subsequent layers, leading to shunts between the top and bottom printed metallic electrodes. Here we demonstrate how aqueous nanoparticle based silver inks can be employed as printed front electrodes using several different roll-to-roll techniques. We thus compare hexagonal silver grids prepared using either roll-to-roll inkjet or roll-to-roll flexographic printing. Both inkjet and flexo grids present a raised topography and were found to perform differently due to only the conductivity of the obtained silver grid. The raised topographies were compared with a roll-to-roll thermally imprinted grid that was filled with silver in a roll-to-roll process, thus presenting an embedded topography. The embedded grid and the flexo grid were found to perform equally well, with the flexographic technique currently presenting the fastest processing and the lowest silver use, whereas the embedded grid presents the maximally achievable optical transparency and conductivity. Polymer solar cells were prepared in the same step, using roll-to-roll slot-die coating of zinc oxide as the electron transport layer, poly-3-hexylthiophene:phenyl-C(61)-butyric acid methyl ester (P3HT:PCBM) as the active layer and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the top electrode, along with a flat bed screen printed silver grid. The power conversion efficiency (PCE) obtained for large area devices (6 cm(2)) was 1.84%, 0.79% and 1.72%, respectively, for thermally imprinted, inkjet and flexographic silver grids, tested outside under the real sun. Central to all three approaches was that they

  4. Silver front electrode grids for ITO-free all printed polymer solar cells with embedded and raised topographies, prepared by thermal imprint, flexographic and inkjet roll-to-roll processes.

    PubMed

    Yu, Jong-Su; Kim, Inyoung; Kim, Jung-Su; Jo, Jeongdai; Larsen-Olsen, Thue T; Søndergaard, Roar R; Hösel, Markus; Angmo, Dechan; Jørgensen, Mikkel; Krebs, Frederik C

    2012-09-28

    Semitransparent front electrodes for polymer solar cells, that are printable and roll-to-roll processable under ambient conditions using different approaches, are explored in this report. The excellent smoothness of indium-tin-oxide (ITO) electrodes has traditionally been believed to be difficult to achieve using printed front grids, as surface topographies accumulate when processing subsequent layers, leading to shunts between the top and bottom printed metallic electrodes. Here we demonstrate how aqueous nanoparticle based silver inks can be employed as printed front electrodes using several different roll-to-roll techniques. We thus compare hexagonal silver grids prepared using either roll-to-roll inkjet or roll-to-roll flexographic printing. Both inkjet and flexo grids present a raised topography and were found to perform differently due to only the conductivity of the obtained silver grid. The raised topographies were compared with a roll-to-roll thermally imprinted grid that was filled with silver in a roll-to-roll process, thus presenting an embedded topography. The embedded grid and the flexo grid were found to perform equally well, with the flexographic technique currently presenting the fastest processing and the lowest silver use, whereas the embedded grid presents the maximally achievable optical transparency and conductivity. Polymer solar cells were prepared in the same step, using roll-to-roll slot-die coating of zinc oxide as the electron transport layer, poly-3-hexylthiophene:phenyl-C(61)-butyric acid methyl ester (P3HT:PCBM) as the active layer and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the top electrode, along with a flat bed screen printed silver grid. The power conversion efficiency (PCE) obtained for large area devices (6 cm(2)) was 1.84%, 0.79% and 1.72%, respectively, for thermally imprinted, inkjet and flexographic silver grids, tested outside under the real sun. Central to all three approaches was that they

  5. Preparation of flexible organic solar cells with highly conductive and transparent metal-oxide multilayer electrodes based on silver oxide.

    PubMed

    Yun, Jungheum; Wang, Wei; Bae, Tae Sung; Park, Yeon Hyun; Kang, Yong-Cheol; Kim, Dong-Ho; Lee, Sunghun; Lee, Gun-Hwan; Song, Myungkwan; Kang, Jae-Wook

    2013-10-23

    We report that significantly more transparent yet comparably conductive AgOx films, when compared to Ag films, are synthesized by the inclusion of a remarkably small amount of oxygen (i.e., 2 or 3 atom %) in thin Ag films. An 8 nm thick AgOx (O/Ag=2.4 atom %) film embedded between 30 nm thick ITO films (ITO/AgOx/ITO) achieves a transmittance improvement of 30% when compared to a conventional ITO/Ag/ITO electrode with the same configuration by retaining the sheet resistance in the range of 10-20 Ω sq(-1). The high transmittance provides an excellent opportunity to improve the power-conversion efficiency of organic solar cells (OSCs) by successfully matching the transmittance spectral range of the electrode to the optimal absorption region of low band gap photoactive polymers, which is highly limited in OSCs utilizing conventional ITO/Ag/ITO electrodes. An improvement of the power-conversion efficiency from 4.72 to 5.88% is achieved from highly flexible organic solar cells (OSCs) fabricated on poly(ethylene terephthalate) polymer substrates by replacing the conventional ITO/Ag/ITO electrode with the ITO/AgOx/ITO electrode. This novel transparent electrode can facilitate a cost-effective, high-throughput, room-temperature fabrication solution for producing large-area flexible OSCs on heat-sensitive polymer substrates with excellent power-conversion efficiencies. PMID:24060352

  6. Preliminary flight prototype silver ion monitoring system

    NASA Technical Reports Server (NTRS)

    Brady, J.

    1974-01-01

    The design, fabrication, and testing of a preliminary flight prototype silver ion monitoring system based on potentiometric principles and utilizing a solid-state silver sulfide electrode paired with a pressurized double-junction reference electrode housing a replaceable electrolyte reservoir is described. The design provides automatic electronic calibration utilizing saturated silver bromide solution as a silver ion standard. The problem of loss of silver ion from recirculating fluid, its cause, and corrective procedures are reported. The instability of the silver sulfide electrode is discussed as well as difficulties met in implementing the autocalibration procedure.

  7. Interface shear-strength properties of roughened HDPE

    SciTech Connect

    Orman, M.E. )

    1994-04-01

    Since 1988, when roughened high-density polyethylene (HDPE) membrane was first introduced to the marketplace, manufacturers have publicized its superior interface frictional characteristics compared to smooth HDPE membrane. Engineers soon began using roughened membranes to help increase the resisting forces along the geosynthetic interfaces of their lined impoundment designs. From the Kettleman Hills landfill failure the authors learned the importance of geosynthetic interface shear strength testing and how much these interfaces can effect a design. Large-scale interface shear testing is now routinely performed by engineers as part of the design process. There are currently four major manufacturers of roughened HDPE in the US. As part of this study, it was determined that roughened membranes have texturing depths that range between 0.3 and 0.7 mm. The depths of texturing currently available appear to be deep enough to mobilize the full shear strength for most fine-grained materials. However, the results of this study showed that the available depth of texturing may not be enough to fully mobilize material shear strengths of coarse-grained materials. This technical note presents the results of large-scale direct shear interface friction tests between two types of granular materials and smooth and roughened HDPE. The results of this testing confirms the importance of testing all geosynthetic interfaces when performing a lined-containment analysis and design. It also appears that there is a direct relationship between the depth of texturing and the amount of granular material shear strength that is mobilized. This relationship is dependent on the grain size of the material and its ability to interlock with the texturing.

  8. Electrocatalytic simultaneous determination of ascorbic acid, uric acid and L-Cysteine in real samples using quercetin silver nanoparticles-graphene nanosheets modified glassy carbon electrode

    NASA Astrophysics Data System (ADS)

    Zare, Hamid R.; Jahangiri-Dehaghani, Fahime; Shekari, Zahra; Benvidi, Ali

    2016-07-01

    By immobilizing of quercetin at the surface of a glassy carbon electrode modified with silver nanoparticles and graphene nanosheets (Q-AgNPs-GNs-GCE) a new sensor has been fabricated. The cyclic voltammogram of Q-AgNPs-GNs-GCE shows a stable redox couple with surface confined characteristics. Q-AgNPs-GNs-GCE demonstrated a high catalytic activity for L-Cysteine (L-Cys) oxidation. Results indicated that L-Cys peak potential at Q-AgNPs-GNs-GCE shifted to less positive values compared to GNs-GCE or AgNPs-GCE. Also, the kinetic parameters such as the electron transfer coefficient,, and the heterogeneous electron transfer rate constant, k‧, for the oxidation of L-Cys at the Q-AgNPs-GNs-GCE surface were estimated. In differential pulse voltammetric determination, the detection limit of L-Cys was obtained 0.28 μM, and the calibration plots were linear within two ranges of 0.9-12.4 μM and 12.4-538.5 μM of L-Cys. Also, the proposed modified electrode is used for the simultaneous determinations of ascorbic acid (AA), uric acid (UA), and L-Cys. Finally, this study has demonstrated the practical analytical utility of the sensor for determination of AA in vitamin C tablet, L-Cys in a milk sample and UA in a human urine sample.

  9. Silver Nanowires Binding with Sputtered ZnO to Fabricate Highly Conductive and Thermally Stable Transparent Electrode for Solar Cell Applications.

    PubMed

    Singh, Manjeet; Rana, Tanka R; Kim, SeongYeon; Kim, Kihwan; Yun, Jae Ho; Kim, JunHo

    2016-05-25

    Silver nanowire (AgNW) film has been demonstrated as excellent and low cost transparent electrode in organic solar cells as an alternative to replace scarce and expensive indium tin oxide (ITO). However, the low contact area and weak adhesion with low-lying surface as well as junction resistance between nanowires have limited the applications of AgNW film to thin film solar cells. To resolve this problem, we fabricated AgNW film as transparent conductive electrode (TCE) by binding with a thin layer of sputtered ZnO (40 nm) which not only increased contact area with low-lying surface in thin film solar cell but also improved conductivity by connecting AgNWs at the junction. The TCE thus fabricated exhibited transparency and sheet resistance of 92% and 20Ω/□, respectively. Conductive atomic force microscopy (C-AFM) study revealed the enhancement of current collection vertically and laterally through AgNWs after coating with ZnO thin film. The CuInGaSe2 solar cell with TCE of our AgNW(ZnO) demonstrated the maximum power conversion efficiency of 13.5% with improved parameters in comparison to solar cell fabricated with conventional ITO as TCE. PMID:27149372

  10. Silver Nanowires Binding with Sputtered ZnO to Fabricate Highly Conductive and Thermally Stable Transparent Electrode for Solar Cell Applications.

    PubMed

    Singh, Manjeet; Rana, Tanka R; Kim, SeongYeon; Kim, Kihwan; Yun, Jae Ho; Kim, JunHo

    2016-05-25

    Silver nanowire (AgNW) film has been demonstrated as excellent and low cost transparent electrode in organic solar cells as an alternative to replace scarce and expensive indium tin oxide (ITO). However, the low contact area and weak adhesion with low-lying surface as well as junction resistance between nanowires have limited the applications of AgNW film to thin film solar cells. To resolve this problem, we fabricated AgNW film as transparent conductive electrode (TCE) by binding with a thin layer of sputtered ZnO (40 nm) which not only increased contact area with low-lying surface in thin film solar cell but also improved conductivity by connecting AgNWs at the junction. The TCE thus fabricated exhibited transparency and sheet resistance of 92% and 20Ω/□, respectively. Conductive atomic force microscopy (C-AFM) study revealed the enhancement of current collection vertically and laterally through AgNWs after coating with ZnO thin film. The CuInGaSe2 solar cell with TCE of our AgNW(ZnO) demonstrated the maximum power conversion efficiency of 13.5% with improved parameters in comparison to solar cell fabricated with conventional ITO as TCE.

  11. Critical Role of Diels–Adler Adducts to Realise Stretchable Transparent Electrodes Based on Silver Nanowires and Silicone Elastomer

    NASA Astrophysics Data System (ADS)

    Heo, Gaeun; Pyo, Kyoung-Hee; Lee, Da Hee; Kim, Youngmin; Kim, Jong-Woong

    2016-05-01

    This paper presents the successful fabrication of a transparent electrode comprising a sandwich structure of silicone/Ag nanowires (AgNWs)/silicone equipped with Diels–Alder (DA) adducts as crosslinkers to realise highly stable stretchability. Because of the reversible DA reaction, the crosslinked silicone successfully bonds with the silicone overcoat, which should completely seal the electrode. Thus, any surrounding liquid cannot leak through the interfaces among the constituents. Furthermore, the nanowires are protected by the silicone cover when they are stressed by mechanical loads such as bending, folding, and stretching. After delicate optimisation of the layered silicone/AgNW/silicone sandwich structure, a stretchable transparent electrode which can withstand 1000 cycles of 50% stretching–releasing with an exceptionally high stability and reversibility was fabricated. This structure can be used as a transparent strain sensor; it possesses a strong piezoresistivity with a gauge factor greater than 11.

  12. Critical Role of Diels–Adler Adducts to Realise Stretchable Transparent Electrodes Based on Silver Nanowires and Silicone Elastomer

    PubMed Central

    Heo, Gaeun; Pyo, Kyoung-hee; Lee, Da Hee; Kim, Youngmin; Kim, Jong-Woong

    2016-01-01

    This paper presents the successful fabrication of a transparent electrode comprising a sandwich structure of silicone/Ag nanowires (AgNWs)/silicone equipped with Diels–Alder (DA) adducts as crosslinkers to realise highly stable stretchability. Because of the reversible DA reaction, the crosslinked silicone successfully bonds with the silicone overcoat, which should completely seal the electrode. Thus, any surrounding liquid cannot leak through the interfaces among the constituents. Furthermore, the nanowires are protected by the silicone cover when they are stressed by mechanical loads such as bending, folding, and stretching. After delicate optimisation of the layered silicone/AgNW/silicone sandwich structure, a stretchable transparent electrode which can withstand 1000 cycles of 50% stretching–releasing with an exceptionally high stability and reversibility was fabricated. This structure can be used as a transparent strain sensor; it possesses a strong piezoresistivity with a gauge factor greater than 11. PMID:27140436

  13. A spray-coating process for highly conductive silver nanowire networks as the transparent top-electrode for small molecule organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Selzer, Franz; Weiß, Nelli; Kneppe, David; Bormann, Ludwig; Sachse, Christoph; Gaponik, Nikolai; Eychmüller, Alexander; Leo, Karl; Müller-Meskamp, Lars

    2015-01-01

    We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 Ω □-1 at 87.4% transparency (80.0% with substrate). By spraying our novel AgNW dispersion in air onto the vacuum-processed organic p-i-n type solar cells, we obtain working solar cells with a power conversion efficiency (PCE) of 1.23%, compared to the air exposed reference devices employing thermally evaporated thin metal layers as the top-electrode.We present a novel top-electrode spray-coating process for the solution-based deposition of silver nanowires (AgNWs) onto vacuum-processed small molecule organic electronic solar cells. The process is compatible with organic light emitting diodes (OLEDs) and organic light emitting thin film transistors (OLETs) as well. By modifying commonly synthesized AgNWs with a perfluorinated methacrylate, we are able to disperse these wires in a highly fluorinated solvent. This solvent does not dissolve most organic materials, enabling a top spray-coating process for sensitive small molecule and polymer-based devices. The optimized preparation of the novel AgNW dispersion and spray-coating at only 30 °C leads to high performance electrodes directly after the deposition, exhibiting a sheet resistance of 10.0 Ω □-1 at 87

  14. Highly stretchable and mechanically stable transparent electrode based on composite of silver nanowires and polyurethane-urea.

    PubMed

    Kim, Dong-Hwan; Yu, Ki-Cheol; Kim, Youngmin; Kim, Jong-Woong

    2015-07-22

    Transparent electrodes based on conventional indium-tin oxide (ITO) can hardly meet the requirements of future generations of stretchable electronic devices, including artificial skins, stretchable displays, sensors, and actuators, because they cannot retain high conductivity under substantial stretching and bending deformation. Here we suggest a new approach for fabricating highly stretchable and transparent electrodes with good stability in environments where they would be stretched repeatedly. We designed polyurethane-urea (PUU), a urethane-based polymer, to enhance the adhesion between Ag nanowires (AgNWs) and poly(dimethylsiloxane) (PDMS). The adhesion could be further improved when irradiated by intense pulsed light (IPL). After delicate optimization of the layered AgNW/PUU/PDMS structure, we fabricated a stretchable transparent electrode that could withstand 100 cycles of 50% stretching-releasing, with exceptionally high stability and reversibility. This newly developed electrode is therefore expected to be directly applicable to a wide range of high-performance, low-cost, stretchable electronic devices. PMID:26135228

  15. High frequency reference electrode

    DOEpatents

    Kronberg, James W.

    1994-01-01

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or "halo" at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes.

  16. High frequency reference electrode

    DOEpatents

    Kronberg, J.W.

    1994-05-31

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or halo' at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes. 4 figs.

  17. Metal-oxide thin-film transistor-based pH sensor with a silver nanowire top gate electrode

    NASA Astrophysics Data System (ADS)

    Yoo, Tae-Hee; Sang, Byoung-In; Wang, Byung-Yong; Lim, Dae-Soon; Kang, Hyun Wook; Choi, Won Kook; Lee, Young Tack; Oh, Young-Jei; Hwang, Do Kyung

    2016-04-01

    Amorphous InGaZnO (IGZO) metal-oxide-semiconductor thin-film transistors (TFTs) are one of the most promising technologies to replace amorphous and polycrystalline Si TFTs. Recently, TFT-based sensing platforms have been gaining significant interests. Here, we report on IGZO transistor-based pH sensors in aqueous medium. In order to achieve stable operation in aqueous environment and enhance sensitivity, we used Al2O3 grown by using atomic layer deposition (ALD) and a porous Ag nanowire (NW) mesh as the top gate dielectric and electrode layers, respectively. Such devices with a Ag NW mesh at the top gate electrode rapidly respond to the pH of solutions by shifting the turn-on voltage. Furthermore, the output voltage signals induced by the voltage shifts can be directly extracted by implantation of a resistive load inverter.

  18. Fast and low-temperature sintering of silver complex using oximes as a potential reducing agent for solution-processible, highly conductive electrodes.

    PubMed

    Yoo, Ji Hoon; Han, Dae Sang; Park, Su Bin; Chae, Jangwoo; Kim, Ji Man; Kwak, Jeonghun

    2014-11-21

    Highly conductive, solution-processed silver thin-films were obtained at a low sintering temperature of 100 °C in a short sintering time of 10 min by introducing oximes as a potential reductant for silver complex. The thermal properties and reducibility of three kinds of oximes, acetone oxime, 2-butanone oxime, and one dimethylglyoxime, were investigated as a reducing agent, and we found that the thermal decomposition product of oximes (ketones) accelerated the conversion of silver complex into highly conductive silver at low sintering temperature in a short time. Using the acetone oxime, the silver thin-film exhibited the lowest surface resistance (0.91 Ω sq(-1)) compared to those sing other oximes. The silver thin-film also showed a high reflectance of 97.8%, which is comparable to evaporated silver films. We also demonstrated inkjet printed silver patterns with the oxime-added silver complex inks.

  19. Influence of silver-decorated multi-walled carbon nanotubes on electrochemical performance of polyaniline-based electrodes

    SciTech Connect

    Kim, Ki-Seok; Park, Soo-Jin

    2011-10-15

    In this work, silver (Ag) nanoparticles were deposited on multi-walled carbon nanotubes (MWNTs) by chemical reduction while Ag-decorated MWNTs (Ag-MWNTs)/polyaniline (PANI) composites were prepared by oxidation polymerization. The effect of the Ag incorporated into the interface of the composites on the electrochemical performance of the MWNTs/PANI was investigated. It was found that highly dispersed Ag nanoparticles were deposited onto the MWNTs, and the Ag-MWNTs were successfully coated by PANI. According to cyclic voltammograms, the Ag-MWNTs/PANI exhibited significantly increased electrochemical performances compared to MWNTs/PANI and the highest specific capacitance obtained of MWNTs/PANI and 0.15 M Ag-MWNTs/PANI was 162 F/g and 205 F/g, respectively. This indicated that Ag nanoparticles that were deposited onto the MWNTs caused an enhanced electrochemical performance of the MWNTs/PANI due to their high electric conductivity, which resulted in an increase of the charge transfer between the MWNTs and PANI by a bridge effect. - Graphical Abstract: The current density of MWNTs/PANI increased with increasing the Ag concentration due to the bridge effect of Ag nanoparticles incorporated between MWNTs and PANI. Highlights: > We fabricated the silver nanoparticle decorated MWNTs/PANI composites. > Ag-MWNTs/PANI showed enhanced electrical conductivity compared to MWNTs/PANI. > Specific capacitance (205 F/g) of Ag-MWNTs/PANI was higher than that of MWNTs/PANI. > Ag nanoparticles serve as catalytic materials at interface between MWNTs and PANI.

  20. Rapid synthesis of ultra-long silver nanowires for tailor-made transparent conductive electrodes: proof of concept in organic solar cells

    NASA Astrophysics Data System (ADS)

    José Andrés, Luis; Menéndez, María Fe; Gómez, David; Martínez, Ana Luisa; Bristow, Noel; Kettle, Jeffrey Paul; Menéndez, Armando; Ruiz, Bernardino

    2015-07-01

    Rapid synthesis of ultralong silver nanowires (AgNWs) has been obtained using a one-pot polyol-mediated synthetic procedure. The AgNWs have been prepared from the base materials in less than one hour with nanowire lengths reaching 195 μm, which represents the quickest synthesis and one of the highest reported aspect ratios to date. These results have been achieved through a joint analysis of all reaction parameters, which represents a clear progress beyond the state of the art. Dispersions of the AgNWs have been used to prepare thin, flexible, transparent and conducting films using spray coating. Due to the higher aspect ratio, an improved electrical percolation network is observed. This allows a low sheet resistance (RS = 20.2 Ω/sq), whilst maintaining high optical film transparency (T = 94.7%), driving to the highest reported figure-of-merit (FoM = 338). Owing to the light-scattering influence of the AgNWs, the density of the AgNW network can also be varied to enable controllability of the optical haze through the sample. Based on the identification of the optimal haze value, organic photovoltaics (OPVs) have been fabricated using the AgNWs as the transparent electrode and have been benchmarked against indium tin oxide (ITO) electrodes. Overall, the performance of OPVs made using AgNWs sees a small decrease in power conversion efficiency (PCE), primarily due to a fall in open-circuit voltage (50 mV). This work indicates that AgNWs can provide a low cost, rapid and roll-to-roll compatible alternative to ITO in OPVs, with only a small compromise in PCE needed.

  1. Rapid synthesis of ultra-long silver nanowires for tailor-made transparent conductive electrodes: proof of concept in organic solar cells.

    PubMed

    José Andrés, Luis; Fe Menéndez, María; Gómez, David; Luisa Martínez, Ana; Bristow, Noel; Paul Kettle, Jeffrey; Menéndez, Armando; Ruiz, Bernardino

    2015-07-01

    Rapid synthesis of ultralong silver nanowires (AgNWs) has been obtained using a one-pot polyol-mediated synthetic procedure. The AgNWs have been prepared from the base materials in less than one hour with nanowire lengths reaching 195 μm, which represents the quickest synthesis and one of the highest reported aspect ratios to date. These results have been achieved through a joint analysis of all reaction parameters, which represents a clear progress beyond the state of the art. Dispersions of the AgNWs have been used to prepare thin, flexible, transparent and conducting films using spray coating. Due to the higher aspect ratio, an improved electrical percolation network is observed. This allows a low sheet resistance (RS = 20.2 Ω/sq), whilst maintaining high optical film transparency (T = 94.7%), driving to the highest reported figure-of-merit (FoM = 338). Owing to the light-scattering influence of the AgNWs, the density of the AgNW network can also be varied to enable controllability of the optical haze through the sample. Based on the identification of the optimal haze value, organic photovoltaics (OPVs) have been fabricated using the AgNWs as the transparent electrode and have been benchmarked against indium tin oxide (ITO) electrodes. Overall, the performance of OPVs made using AgNWs sees a small decrease in power conversion efficiency (PCE), primarily due to a fall in open-circuit voltage (50 mV). This work indicates that AgNWs can provide a low cost, rapid and roll-to-roll compatible alternative to ITO in OPVs, with only a small compromise in PCE needed. PMID:26056864

  2. The Use of Silver Solid Amalgam Electrodes for Voltammetric and Amperometric Determination of Nitrated Polyaromatic Compounds Used as Markers of Incomplete Combustion

    PubMed Central

    Yosypchuk, Oksana; Karásek, Jindřich; Vyskočil, Vlastimil; Barek, Jiří; Pecková, Karolina

    2012-01-01

    Genotoxic nitrated polycyclic aromatic hydrocarbons (NPAHs) are formed during incomplete combustion processes by reaction of polycyclic aromatic hydrocarbons (PAHs) with atmospheric nitrogen oxides. 1-Nitropyrene, 2-nitrofluorene, and 3-nitrofluoranthene as the dominating substances are used as markers of NPAHs formation by these processes. In the presented study, voltammetric properties and quantification of these compounds and of 5-nitroquinoline (as a representative of environmentally important genotoxic heterocyclic compounds) have been investigated using a mercury meniscus modified silver solid amalgam electrode (m-AgSAE), which represent a nontoxic alternative to traditional mercury electrodes. Linear calibration curves over three orders of magnitude and limits of determination mostly in the 10−7 mol L−1 concentration range were obtained using direct current and differential pulse voltammetry. Further, satisfactory HPLC separation of studied analytes in fifteen minutes was achieved using 0.01 mol L−1 phosphate buffer, pH 7.0 : methanol (15 : 85, v/v) mobile phase, and C18 reversed stationary phase. Limits of detection of around 1 · 10−5 mol L−1 were achieved using amperometric detection at m-AgSAE in wall-jet arrangement for all studied analytes. Practical applicability of this technique was demonstrated on the determination of 1-nitropyrene, 2-nitrofluorene, 3-nitrofluoranthene, and 5-nitroquinoline in drinking water after their preliminary separation and preconcentration using solid phase extraction with the limits of detection around 1 · 10−6 mol L−1. PMID:22619628

  3. The use of silver solid amalgam electrodes for voltammetric and amperometric determination of nitrated polyaromatic compounds used as markers of incomplete combustion.

    PubMed

    Yosypchuk, Oksana; Karásek, Jindřich; Vyskočil, Vlastimil; Barek, Jiří; Pecková, Karolina

    2012-01-01

    Genotoxic nitrated polycyclic aromatic hydrocarbons (NPAHs) are formed during incomplete combustion processes by reaction of polycyclic aromatic hydrocarbons (PAHs) with atmospheric nitrogen oxides. 1-Nitropyrene, 2-nitrofluorene, and 3-nitrofluoranthene as the dominating substances are used as markers of NPAHs formation by these processes. In the presented study, voltammetric properties and quantification of these compounds and of 5-nitroquinoline (as a representative of environmentally important genotoxic heterocyclic compounds) have been investigated using a mercury meniscus modified silver solid amalgam electrode (m-AgSAE), which represent a nontoxic alternative to traditional mercury electrodes. Linear calibration curves over three orders of magnitude and limits of determination mostly in the 10(-7) mol L(-1) concentration range were obtained using direct current and differential pulse voltammetry. Further, satisfactory HPLC separation of studied analytes in fifteen minutes was achieved using 0.01 mol L(-1) phosphate buffer, pH 7.0 : methanol (15 : 85, v/v) mobile phase, and C(18) reversed stationary phase. Limits of detection of around 1 · 10(-5) mol L(-1) were achieved using amperometric detection at m-AgSAE in wall-jet arrangement for all studied analytes. Practical applicability of this technique was demonstrated on the determination of 1-nitropyrene, 2-nitrofluorene, 3-nitrofluoranthene, and 5-nitroquinoline in drinking water after their preliminary separation and preconcentration using solid phase extraction with the limits of detection around 1 · 10(-6) mol L(-1). PMID:22619628

  4. Flexible ambipolar organic field-effect transistors with reverse-offset-printed silver electrodes for a complementary inverter.

    PubMed

    Park, Junsu; Kim, Minseok; Yeom, Seung-Won; Ha, Hyeon Jun; Song, Hyenggun; Min Jhon, Young; Kim, Yun-Hi; Ju, Byeong-Kwon

    2016-06-01

    We report ambipolar organic field-effect transistors and complementary inverter circuits with reverse-offset-printed (ROP) Ag electrodes fabricated on a flexible substrate. A diketopyrrolopyrrole-based co-polymer (PDPP-TAT) was used as the semiconductor and poly(methyl methacrylate) was used as the gate insulator. Considerable improvement is observed in the n-channel electrical characteristics by inserting a cesium carbonate (Cs2CO3) as the electron-injection/hole-blocking layer at the interface between the semiconductors and the electrodes. The saturation mobility values are 0.35 cm(2) V(-1) s(-1) for the p-channel and 0.027 cm(2) V(-1) s(-1) for the n-channel. A complementary inverter is demonstrated based on the ROP process, and it is selectively controlled by the insertion of Cs2CO3 onto the n-channel region via thermal evaporation. Moreover, the devices show stable operation during the mechanical bending test using tensile strains ranging from 0.05% to 0.5%. The results confirm that these devices have great potential for use in flexible and inexpensive integrated circuits over a large area. PMID:27114463

  5. Flexible ambipolar organic field-effect transistors with reverse-offset-printed silver electrodes for a complementary inverter

    NASA Astrophysics Data System (ADS)

    Park, Junsu; Kim, Minseok; Yeom, Seung-Won; Ha, Hyeon Jun; Song, Hyenggun; Jhon, Young Min; Kim, Yun-Hi; Ju, Byeong-Kwon

    2016-06-01

    We report ambipolar organic field-effect transistors and complementary inverter circuits with reverse-offset-printed (ROP) Ag electrodes fabricated on a flexible substrate. A diketopyrrolopyrrole-based co-polymer (PDPP-TAT) was used as the semiconductor and poly(methyl methacrylate) was used as the gate insulator. Considerable improvement is observed in the n-channel electrical characteristics by inserting a cesium carbonate (Cs2CO3) as the electron-injection/hole-blocking layer at the interface between the semiconductors and the electrodes. The saturation mobility values are 0.35 cm2 V‑1 s‑1 for the p-channel and 0.027 cm2 V‑1 s‑1 for the n-channel. A complementary inverter is demonstrated based on the ROP process, and it is selectively controlled by the insertion of Cs2CO3 onto the n-channel region via thermal evaporation. Moreover, the devices show stable operation during the mechanical bending test using tensile strains ranging from 0.05% to 0.5%. The results confirm that these devices have great potential for use in flexible and inexpensive integrated circuits over a large area.

  6. Flexible ambipolar organic field-effect transistors with reverse-offset-printed silver electrodes for a complementary inverter

    NASA Astrophysics Data System (ADS)

    Park, Junsu; Kim, Minseok; Yeom, Seung-Won; Ha, Hyeon Jun; Song, Hyenggun; Jhon, Young Min; Kim, Yun-Hi; Ju, Byeong-Kwon

    2016-06-01

    We report ambipolar organic field-effect transistors and complementary inverter circuits with reverse-offset-printed (ROP) Ag electrodes fabricated on a flexible substrate. A diketopyrrolopyrrole-based co-polymer (PDPP-TAT) was used as the semiconductor and poly(methyl methacrylate) was used as the gate insulator. Considerable improvement is observed in the n-channel electrical characteristics by inserting a cesium carbonate (Cs2CO3) as the electron-injection/hole-blocking layer at the interface between the semiconductors and the electrodes. The saturation mobility values are 0.35 cm2 V-1 s-1 for the p-channel and 0.027 cm2 V-1 s-1 for the n-channel. A complementary inverter is demonstrated based on the ROP process, and it is selectively controlled by the insertion of Cs2CO3 onto the n-channel region via thermal evaporation. Moreover, the devices show stable operation during the mechanical bending test using tensile strains ranging from 0.05% to 0.5%. The results confirm that these devices have great potential for use in flexible and inexpensive integrated circuits over a large area.

  7. Flexible ambipolar organic field-effect transistors with reverse-offset-printed silver electrodes for a complementary inverter.

    PubMed

    Park, Junsu; Kim, Minseok; Yeom, Seung-Won; Ha, Hyeon Jun; Song, Hyenggun; Min Jhon, Young; Kim, Yun-Hi; Ju, Byeong-Kwon

    2016-06-01

    We report ambipolar organic field-effect transistors and complementary inverter circuits with reverse-offset-printed (ROP) Ag electrodes fabricated on a flexible substrate. A diketopyrrolopyrrole-based co-polymer (PDPP-TAT) was used as the semiconductor and poly(methyl methacrylate) was used as the gate insulator. Considerable improvement is observed in the n-channel electrical characteristics by inserting a cesium carbonate (Cs2CO3) as the electron-injection/hole-blocking layer at the interface between the semiconductors and the electrodes. The saturation mobility values are 0.35 cm(2) V(-1) s(-1) for the p-channel and 0.027 cm(2) V(-1) s(-1) for the n-channel. A complementary inverter is demonstrated based on the ROP process, and it is selectively controlled by the insertion of Cs2CO3 onto the n-channel region via thermal evaporation. Moreover, the devices show stable operation during the mechanical bending test using tensile strains ranging from 0.05% to 0.5%. The results confirm that these devices have great potential for use in flexible and inexpensive integrated circuits over a large area.

  8. Electrochemical sensor using neomycin-imprinted film as recognition element based on chitosan-silver nanoparticles/graphene-multiwalled carbon nanotubes composites modified electrode.

    PubMed

    Lian, Wenjing; Liu, Su; Yu, Jinghua; Li, Jie; Cui, Min; Xu, Wei; Huang, Jiadong

    2013-06-15

    A novel imprinted electrochemical sensor for neomycin recognition was developed based on chitosan-silver nanoparticles (CS-SNP)/graphene-multiwalled carbon nanotubes (GR-MWCNTs) composites decorated gold electrode. Molecularly imprinted polymers (MIPs) were synthesized by electropolymerization using neomycin as the template, and pyrrole as the monomer. The mechanism of the fabrication process and a number of factors affecting the activity of the imprinted sensor have been discussed and optimized. The characterization of imprinted sensor has been carried out by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The performance of the proposed imprinted sensor has been investigated using cyclic voltammetry (CV) and amperometry. Under the optimized conditions, the linear range of the sensor was from 9×10(-9)mol/L to 7×10(-6)mol/L, with the limit of detection (LOD) of 7.63×10(-9)mol/L (S/N=3). The film exhibited high binding affinity and selectivity towards the template neomycin, as well as good reproducibility and stability. Furthermore, the proposed sensor was applied to determine the neomycin in milk and honey samples based on its good reproducibility and stability, and the acceptable recovery implied its feasibility for practical application.

  9. A solution-processed molybdenum oxide treated silver nanowire network: a highly conductive transparent conducting electrode with superior mechanical and hole injection properties.

    PubMed

    Chang, Jung-Hao; Chiang, Kai-Ming; Kang, Hao-Wei; Chi, Wei-Jung; Chang, Jung-Hung; Wu, Chih-I; Lin, Hao-Wu

    2015-03-14

    We demonstrate the fabrication of solution-processed MoOx-treated (s-MoOx) silver nanowire (AgNW) transparent conductive electrodes (TCEs) utilizing low-temperature (sub-100 °C) processes. The s-MoOx aggregates around the AgNW and forms gauze-like MoOx thin films between the mesh, which can effectively lower the sheet resistance by more than two orders of magnitude. Notably, these s-MoOx-treated AgNW TCEs exhibit a combination of several promising characteristics, such as a high and broad transmittance across a wavelength range of 400 to 1000 nm, transmission of up to 96.8%, a low sheet resistance of 29.8 ohm sq(-1), a low haze value of 0.90%, better mechanical properties against bending and adhesion tests, and preferable gap states for efficient hole injection in optoelectronic applications. By utilizing these s-MoOx-treated AgNW TCEs as the anode in ITO-free organic light emitting diodes, promising performance of 29.2 lm W(-1) and 10.3% external quantum efficiency are demonstrated. The versatile, multi-functional s-MoOx treatment presented here paves the way for the use of low-temperature, solution-processed MoOx as both a nanowire linker and a hole injection interfacial layer for future flexible optoelectronic devices.

  10. Study of surface-modified PVP gate dielectric in organic thin film transistors with the nano-particle silver ink source/drain electrode.

    PubMed

    Yun, Ho-Jin; Ham, Yong-Hyun; Shin, Hong-Sik; Jeong, Kwang-Seok; Park, Jeong-Gyu; Choi, Deuk-Sung; Lee, Ga-Won

    2011-07-01

    We have fabricated the flexible pentacene based organic thin film transistors (OTFTs) with formulated poly[4-vinylphenol] (PVP) gate dielectrics treated by CF4/O2 plasma on poly[ethersulfones] (PES) substrate. The solution of gate dielectrics is made by adding methylated poly[melamine-co-formaldehyde] (MMF) to PVP. The PVP gate dielectric layer was cross linked at 90 degrees under UV ozone exposure. Source/drain electrodes are formed by micro contact printing (MCP) method using nano particle silver ink for the purposes of low cost and high throughput. The optimized OTFT shows the device performance with field effect mobility of the 0.88 cm2/V s, subthreshold slope of 2.2 V/decade, and on/off current ratios of 1.8 x 10(-6) at -40 V gate bias. We found that hydrophobic PVP gate dielectric surface can influence on the initial film morphologies of pentacene making dense, which is more important for high performance OTFTs than large grain size. Moreover, hydrophobic gate dielelctric surface reduces voids and -OH groups that interrupt the carrier transport in OTFTs.

  11. Graphite grains studded with silver nanoparticles: description and application in promoting direct biocatalysis between heme protein and the resulting carbon paste electrode.

    PubMed

    ElKaoutit, Mohammed; Naggar, Ahmad H; Naranjo-Rodríguez, Ignacio; de Cisneros, José L Hidalgo-Hidalgo

    2012-04-01

    The impregnation of graphite grains with silver nanoparticles (AgNPs) is proposed for making a novel carbon paste electrode (CPE). The resulting material promotes direct electron transfer and direct biocatalysis of embedded heme protein. It is demonstrated that the impregnation of graphite grains with AgNPs of 16-25 nm, incorporated in a CPE, can promote measurable bio-electrochemical phenomena involving hemoglobin and myoglobin. Unlike other biosensors prepared with simple carbon, those based on carbon grains studded with AgNPs show well-defined and quasi-reversible voltammetric peak with heterogeneous electron transfer rate k(s) of approximately 0.037±0.007 and 0.013±0.005s(-1) for hemoglobin and myoglobin, respectively. The embedded proteins also retain their bio-catalytical activity for hydrogen peroxide and nitrite reduction with linear ranges of 0.5-3000 μM and 30-150 μM, sensitivities of 73.6±0.6nA μM(-1) and 5.72±0.11 nA μM(-1), and detection limits close to 0.08 μM and 5.80 μM, for these two analytes respectively. These results support the viability of this preliminary approach for the development of advanced third-generation biosensors. PMID:22154098

  12. Amperometric Detection of Aqueous Silver Ions by Inhibition of Glucose Oxidase Immobilized on Nitrogen-Doped Carbon Nanotube Electrodes.

    PubMed

    Rust, Ian M; Goran, Jacob M; Stevenson, Keith J

    2015-07-21

    An amperometric glucose biosensor based on immobilization of glucose oxidase on nitrogen-doped carbon nanotubes (N-CNTs) was successfully developed for the determination of silver ions. Upon exposure to glucose, a steady-state enzymatic turnover rate was detected through amperometric oxidation of the H2O2 byproduct, directly related to the concentration of glucose in solution. Inhibition of the steady-state enzymatic glucose oxidase reaction by heavy metals ions such as Ag(+), produced a quantitative decrease in the steady-state rate, subsequently creating an ultrasensitive metal ion biosensor through enzymatic inhibition. The Ag(+) biosensor displayed a sensitivity of 2.00 × 10(8) ± 0.06 M(-1), a limit of detection (σ = 3) of 0.19 ± 0.04 ppb, a linear range of 20-200 nM, and sample recovery at 101 ± 2%, all acquired at a low-operating potential of 0.05 V (vs Hg/Hg2SO4). Interestingly, the biosensor does not display a loss in sensitivity with continued use due to the % inhibition based detection scheme: loss of enzyme (from continued use) does not influence the % inhibition, only the overall current associated with the activity loss. The heavy metals Cu(2+) and Co(2+) were also detected using the enzyme biosensor but found to be much less inhibitory, with sensitivities of 1.45 × 10(6) ± 0.05 M(-1) and 2.69 × 10(3) ± 0.07 M(-1), respectively. The mode of GOx inhibition was examined for both Ag(+) and Cu(2+) using Dixon and Cornish-Bowden plots, where a strong correlation was observed between the inhibition constants and the biosensor sensitivity.

  13. Amperometric Detection of Aqueous Silver Ions by Inhibition of Glucose Oxidase Immobilized on Nitrogen-Doped Carbon Nanotube Electrodes.

    PubMed

    Rust, Ian M; Goran, Jacob M; Stevenson, Keith J

    2015-07-21

    An amperometric glucose biosensor based on immobilization of glucose oxidase on nitrogen-doped carbon nanotubes (N-CNTs) was successfully developed for the determination of silver ions. Upon exposure to glucose, a steady-state enzymatic turnover rate was detected through amperometric oxidation of the H2O2 byproduct, directly related to the concentration of glucose in solution. Inhibition of the steady-state enzymatic glucose oxidase reaction by heavy metals ions such as Ag(+), produced a quantitative decrease in the steady-state rate, subsequently creating an ultrasensitive metal ion biosensor through enzymatic inhibition. The Ag(+) biosensor displayed a sensitivity of 2.00 × 10(8) ± 0.06 M(-1), a limit of detection (σ = 3) of 0.19 ± 0.04 ppb, a linear range of 20-200 nM, and sample recovery at 101 ± 2%, all acquired at a low-operating potential of 0.05 V (vs Hg/Hg2SO4). Interestingly, the biosensor does not display a loss in sensitivity with continued use due to the % inhibition based detection scheme: loss of enzyme (from continued use) does not influence the % inhibition, only the overall current associated with the activity loss. The heavy metals Cu(2+) and Co(2+) were also detected using the enzyme biosensor but found to be much less inhibitory, with sensitivities of 1.45 × 10(6) ± 0.05 M(-1) and 2.69 × 10(3) ± 0.07 M(-1), respectively. The mode of GOx inhibition was examined for both Ag(+) and Cu(2+) using Dixon and Cornish-Bowden plots, where a strong correlation was observed between the inhibition constants and the biosensor sensitivity. PMID:26079664

  14. Surface roughening of superalloys by high pressure pure waterjet

    SciTech Connect

    Taylor, T.A.

    1995-12-31

    A high pressure waterjet has been used to study the surface roughening of superalloys as preparation for thermal spraying. Designed experiments for Mar-M 509 and Rene 80 were carried out for the effects of jet pressure and mass of water delivered per unit area. Comparisons were made of several superalloys in terms of erosion, surface roughness and topology. The mechanism of jet erosion of Rene 80 was studied in relation to its metallurgical microstructure. An MCrAlY coating by shrouded plasma spray was made over a waterjet prepared surface with excellent bonding and having an ideally clean interface.

  15. Electrochemical behavior of silver sulfide

    SciTech Connect

    Drouven, B.U.E.

    1982-01-01

    The electrochemical behavior of silver sulfide in sulfuric acid as well as in nitric acid was studied using electrodes made from synthetic silver sulfide. The primary techniques used were potentiostatic, potentiodynamic, galvanostatic and corrosion cell experiments. The cathodic reaction of silver sulfide produces silver and hydrogen sulfide. This reaction mechanism is a sequential two step charge transfer involving a single electron in each step. Silver ions are produced from silver sulfide upon applying an anodic potential. The dissolution rate of silver sulfide can be so high that the formation of silver sulfate occurs which partially covers the silver sulfide surface and inhibits a further rate increase. The sulfur from the silver sulfide will be oxidized at low overpotentials to elemental sulfur; at high overpotentials, the oxidation to sulfate or bisulfate is observed. The results suggest that the catalysis of chalcopyrite by the addition of silver ions is caused by the formation and subsequent dissolution of silver sulfide leaving a porous layer behind. The understanding of the reaction mechanism of silver sulfide dissolution and its optimization will significantly improve the economic evaluation of industrial processes using the catalyzed leaching of chalcopyrite. The present knowledge of the catalysis indicates that other ions may be substituted for silver ions which would increase the feasibility of hydrometallurgical processes.

  16. Silver nanoparticle-decorated carbon nanotubes as bifunctional gas-diffusion electrodes for zinc-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, T.; Kaempgen, M.; Nopphawan, P.; Wee, G.; Mhaisalkar, S.; Srinivasan, M.

    Thin, lightweight, and flexible gas-diffusion electrodes (GDEs) based on freestanding entangled networks of single-walled carbon nanotubes (SWNTs) decorated with Ag nanoparticles (AgNPs) are tested as the air-breathing cathode in a zinc-air battery. The SWNT networks provide a highly porous surface for active oxygen absorption and diffusion. The high conductivity of SWNTs coupled with the catalytic activity of AgNPs for oxygen reduction leads to an improvement in the performance of the zinc-air cell. By modulating the pH value and the reaction time, different sizes of AgNPs are decorated uniformly on the SWNTs, as revealed by transmission electron microscopy and powder X-ray diffraction. AgNPs with sizes of 3-5 nm double the capacity and specific energy of a zinc-air battery as compared with bare SWNTs. The simplified, lightweight architecture shows significant advantages over conventional carbon-based GDEs in terms of weight, thickness and conductivity, and hence may be useful for mobile and portable applications.

  17. Stress induced roughening of superclimbing dislocation in solid 4He

    NASA Astrophysics Data System (ADS)

    Aleinikava, Darya; Kuklov, Anatoly

    2011-03-01

    We investigate numerically superclimb of dislocation in solid 4 He biased by externally imposed chemical potential μ . The effective action takes into account quantum phase slips in the core superfluid as well as the core displacement in Peierls potential within the Granato-Lücke string model. The bias produces stress on the core and this can result in dislocation roughening. Such roughening is characterized by hysteretic behavior at temperatures (T) below some threshold Thyst . At T >Thyst strongresonantpeaksdevelopinthedislocationdifferentialresponse . Thesepeaksexhibitperiodicbehaviorvs μ, with the period determined by Peierls potential and dislocation length. We explain these effects by thermally assisted tunneling of jog-antijog pairs across the barrier created by Peierls potential and the bias. Since superclimbing is controlled by core superflow, speed of sound along the superfluid core exhibits dip-like features at the peak positions. We propose that this effect is seen in the mass transport experiment. We acknowledge support by NSF, grants PHY1005527 and PHY0653135,and by CUNY, grant 63071-00 41.

  18. A solution-processed molybdenum oxide treated silver nanowire network: a highly conductive transparent conducting electrode with superior mechanical and hole injection properties

    NASA Astrophysics Data System (ADS)

    Chang, Jung-Hao; Chiang, Kai-Ming; Kang, Hao-Wei; Chi, Wei-Jung; Chang, Jung-Hung; Wu, Chih-I.; Lin, Hao-Wu

    2015-02-01

    We demonstrate the fabrication of solution-processed MoOx-treated (s-MoOx) silver nanowire (AgNW) transparent conductive electrodes (TCEs) utilizing low-temperature (sub-100 °C) processes. The s-MoOx aggregates around the AgNW and forms gauze-like MoOx thin films between the mesh, which can effectively lower the sheet resistance by more than two orders of magnitude. Notably, these s-MoOx-treated AgNW TCEs exhibit a combination of several promising characteristics, such as a high and broad transmittance across a wavelength range of 400 to 1000 nm, transmission of up to 96.8%, a low sheet resistance of 29.8 ohm sq-1, a low haze value of 0.90%, better mechanical properties against bending and adhesion tests, and preferable gap states for efficient hole injection in optoelectronic applications. By utilizing these s-MoOx-treated AgNW TCEs as the anode in ITO-free organic light emitting diodes, promising performance of 29.2 lm W-1 and 10.3% external quantum efficiency are demonstrated. The versatile, multi-functional s-MoOx treatment presented here paves the way for the use of low-temperature, solution-processed MoOx as both a nanowire linker and a hole injection interfacial layer for future flexible optoelectronic devices.We demonstrate the fabrication of solution-processed MoOx-treated (s-MoOx) silver nanowire (AgNW) transparent conductive electrodes (TCEs) utilizing low-temperature (sub-100 °C) processes. The s-MoOx aggregates around the AgNW and forms gauze-like MoOx thin films between the mesh, which can effectively lower the sheet resistance by more than two orders of magnitude. Notably, these s-MoOx-treated AgNW TCEs exhibit a combination of several promising characteristics, such as a high and broad transmittance across a wavelength range of 400 to 1000 nm, transmission of up to 96.8%, a low sheet resistance of 29.8 ohm sq-1, a low haze value of 0.90%, better mechanical properties against bending and adhesion tests, and preferable gap states for efficient hole

  19. Scaling of local slopes, conservation laws, and anomalous roughening in surface growth.

    PubMed

    López, Juan M; Castro, Mario; Gallego, Rafael

    2005-04-29

    We argue that symmetries and conservation laws greatly restrict the form of the terms entering the long wavelength description of growth models exhibiting anomalous roughening. This is exploited to show by dynamic renormalization group arguments that intrinsic anomalous roughening cannot occur in local growth models. However, some conserved dynamics may display superroughening if a given type of term is present.

  20. NiCd battery electrodes, C-150

    NASA Technical Reports Server (NTRS)

    Holleck, G.; Turchan, M.; Hopkins, J.

    1972-01-01

    Electrodes for a nongassing negative limited nickel-cadmium cell are discussed. The key element is the development of cadmium electrodes with high hydrogen overvoltage. For this, the following electrode structures were manufactured and their physical and electrochemical characteristics were evaluated: (1) silver-sinter-based Cd electrodes, (2) Teflon-bonded Cd electrodes, (3) electrodeposited Cd sponge, and (4) Cd-sinter structures.

  1. Smoothing and roughening of slip surfaces in direct shear experiments

    NASA Astrophysics Data System (ADS)

    Sagy, Amir; Badt, Nir; Hatzor, Yossef H.

    2015-04-01

    , increases as a function of slip amount. The roughness measured after slip can be fitted by a power-law similar to that of the initial tensile surface. In the next series of experiments a similar procedure is applied when the roughness evolution is measured as a function of increasing normal stress for a fixed displacement amount of 10 mm. While samples sheared under a constant normal stress of 5 MPa generated surface smoothing, shearing under normal stress of 7.5 MPa to 15 MPa exhibited surface roughening at the measured range of scales. We find that roughening is correlated with the attained peak shear stress values, stress drop (peak shear stress minus residual shear stress) and with wear accumulation, a novel measurement procedure of which is developed here. Analysis of the sheared samples shows that roughening is generated by sets of dense fractures that significantly damaged the sample in the immediate proximity to large asperities. This roughening is related to penetrative damage during transient wear in rough surfaces.

  2. Gelatin coated electrodes allow prolonged bioelectronic measurements

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Silver electrodes treated with an anodizing electrolyte containing gelatin are used for long term monitoring of bioelectronic potentials in humans. The electrodes do not interact with perspiration, cause skin irritation, or promote the growth of bacteria.

  3. Thermal roughening of GaAs surface by dislocation-induced step-flow sublimation

    NASA Astrophysics Data System (ADS)

    Akhundov, I. O.; Kazantsev, D. M.; Kozhuhov, A. S.; Alperovich, V. L.

    2016-08-01

    The thermal roughening of epitaxial GaAs film surface is studied under anneals at temperatures 700-775 °C in the presence of a saturated Ga-As melt. Surface roughening consists in the formation of spiral “inverted pyramids” on the initially flat surface due to the step-flow sublimation induced by screw dislocations. The observed roughening indicates that, despite the presence of As and Ga vapors provided by the melt, the annealing conditions are shifted from equilibrium towards sublimation.

  4. Silver Sulfadiazine

    MedlinePlus

    Silver sulfadiazine, a sulfa drug, is used to prevent and treat infections of second- and third-degree ... Silver sulfadiazine comes in a cream. Silver sulfadiazine usually is applied once or twice a day. Follow ...

  5. Biomechanical and Histological Evaluation of Roughened Surface Titanium Screws Fabricated by Electron Beam Melting

    PubMed Central

    Yang, Jun; Cai, Hong; Lv, Jia; Zhang, Ke; Leng, Huijie; Wang, Zhiguo; Liu, Zhongjun

    2014-01-01

    Background Various fabrication methods are used to improve the stability and osseointegration of screws within the host bone. The aim of this study was to investigate whether roughened surface titanium screws fabricated by electron beam melting can provide better stability and osseointegration as compared with smooth titanium screws in sheep cervical vertebrae. Methods Roughened surface titanium screws, fabricated by electron beam melting, and conventional smooth surface titanium screws were implanted into sheep for 6 or 12 weeks (groups A and B, respectively). Bone ingrowth and implant stability were assessed with three-dimensional imaging and reconstruction, as well as histological and biomechanical tests. Results No screws in either group showed signs of loosening. Fibrous tissue formation could be seen around the screws at 6 weeks, which was replaced with bone at 12 weeks. Bone volume/total volume, bone surface area/bone volume, and the trabecular number were significantly higher for a define region of interest surrounding the roughened screws than that surrounding the smooth screws at 12 weeks. Indeed, for roughened screws, trabecular number was significantly higher at 12 weeks than at 6 weeks. On mechanical testing, the maximum pullout strength was significantly higher at 12 weeks than at 6 weeks, as expected; however, no significant differences were found between smooth and roughened screws at either time point. The maximum torque to extract the roughened screws was higher than that required for the smooth screws. Conclusions Electron beam melting is a simple and effective method for producing a roughened surface on titanium screws. After 12 weeks, roughened titanium screws demonstrated a high degree of osseointegration and increased torsional resistance to extraction over smooth titanium screws. PMID:24788866

  6. Anomalous Kinetic Roughening of Nanostructured Ag Islands on Liquid Surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Chuhang; Lv, Neng; Zhu, Yuhong; Zhang, Xiaofei; Ye, Gaoxiang

    2012-03-01

    By atomic force microscopy, the surface evolution and kinetic roughening of nanostructured Ag islands on silicone oil surfaces are studied. It is found that the islands are composed of quasi-circular granules with planar size around 50.0 nm, which is approximately independent of nominal thickness d. Our measurement indicates that the geometrical shape of the granules changes from plateau to sphere as d goes up. The dynamic scaling analysis reveal that the roughness exponent α varies between 0.80 and 0.90 as d increases. The average roughness wrms shows power-law relationship with d and the growth exponent β = 0.53 ± 0.03 when d ≤ 4.0 nm. However, wrms deviates obviously from the power-law relationship for the samples with d > 4.0 nm. This anomalous behavior of β is explained by the competition between the shadowing and reemission processes, and then the kinetic evolution and formation mechanism of the islands are presented.

  7. Highly compliant transparent electrodes

    NASA Astrophysics Data System (ADS)

    Shian, Samuel; Diebold, Roger M.; McNamara, Alena; Clarke, David R.

    2012-08-01

    Adaptive optical devices based on electric field induced deformation of dielectric elastomers require transparent and highly compliant electrodes to conform to large shape changes. Electrical, optical, and actuation properties of acrylic elastomer electrodes fabricated with single-walled carbon nanotubes (SWCNTs) and silver nanowires (AgNWs) have been evaluated. Based on these properties, a figure of merit is introduced for evaluating the overall performance of deformable transparent electrodes. This clearly indicates that SWCNTs outperform AgNWs. Under optimal conditions, optical transparency as high as 91% at 190% maximum actuation strain is readily achievable using SWCNT electrodes.

  8. Glass frits coated with silver nanoparticles for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Li, Yingfen; Gan, Weiping; Zhou, Jian; Li, Biyuan

    2015-06-01

    Glass frits coated with silver nanoparticles were prepared by electroless plating. Gum Arabic (GA) was used as the activating agent of glass frits without the assistance of stannous chloride or palladium chloride. The silver-coated glass frits prepared with different GA dosages were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The characterization results indicated that silver-coated glass frits had the structures of both glass and silver. Spherical silver nanoparticles were distributed on the glass frits evenly. The density and particle size of silver nanoparticles on the glass frits can be controlled by adjusting the GA dosage. The silver-coated glass frits were applied to silver pastes to act as both the densification promoter and silver crystallite formation aid in the silver electrodes. The prepared silver-coated glass frits can improve the photovoltaic performances of solar cells.

  9. Silver based batteries for high power applications

    NASA Astrophysics Data System (ADS)

    Karpinski, A. P.; Russell, S. J.; Serenyi, J. R.; Murphy, J. P.

    The present status of silver oxide-zinc technology and applications has been described by Karpinski et al. [A.P. Karpinski, B. Makovetski, S.J. Russell, J.R. Serenyi, D.C. Williams, Silver-Zinc: status of technology and applications, Journal of Power Sources, 80 (1999) 53-60], where the silver-zinc couple is still the preferred choice where high specific energy/energy density, coupled with high specific power/power density are important for high-rate, weight or size/configuration sensitive applications. Perhaps the silver oxide cathode can be considered one of the most versatile electrode materials. When coupled with other anodes and corresponding electrolyte management system, the silver electrode provides for a wide array of electrochemical systems that can be tailored to meet the most demanding, high power requirements. Besides zinc, the most notable include cadmium, iron, metal hydride, and hydrogen electrode for secondary systems, while primary systems include lithium and aluminum. Alloys including silver are also available, such as silver chloride, which when coupled with magnesium or aluminum are primarily used in many seawater applications. The selection and use of these couples is normally the result of a trade-off of many factors. These include performance, safety, risk, reliability, and cost. When high power is required, silver oxide-zinc, silver oxide-aluminum, and silver oxide-lithium are the most energetic. For moderate performance (i.e., lower power), silver oxide-zinc or silver-cadmium would be the system of choice. This paper summarizes the suitability of the silver-based couples, with an emphasis on the silver-zinc system, as primary or rechargeable power sources for high energy/power applications.

  10. Design of a Flow-Through Voltammetric Sensor Based on an Antimony-Modified Silver Electrode for Determining Lithol Rubine B in Cosmetics

    PubMed Central

    Lai-Hao, Wang; Shu-Juan, Huang

    2011-01-01

    Lithol Rubine B (LRB; the disodium salt of 3-hydroxy-4-[(4-methyl-2-sulfophenyl) azo]-2-naphthalenecarboxylic acid) was detected using high-performance liquid chromatography with an electrochemical (antimony film on silver) detector (HPLC-ECD). For direct current (DC) mode, with the current at a constant potential, and measurements with suitable experimental parameters, a linear concentration from 0.125 to 1.80 μg/mL was found. The detection limit of our method was approximately 2.0 ng/mL. An antimony-modified silver detector was used to demonstrate that LRB is electrochemically reduced in acidic media and to analyze commercial cosmetics to determine their LRB content. Findings using HPLC-ECD and HPLC with an ultraviolet detector were comparable. PMID:21603230

  11. Surface-enhanced Raman spectroscopy of amino acids adsorbed on an electrochemically prepared silver surface

    NASA Astrophysics Data System (ADS)

    Stewart, S.; Fredericks, P. M.

    1999-07-01

    An electrochemically roughened silver surface, in conjunction with a Raman microprobe spectrometer, was used to obtain SER spectra of a suite of 19 L-amino acids. The spectra obtained were very different from previously reported SER spectra obtained from silver hydrosols of amino acids. Analysis of the spectra showed that adsorption of all amino acids was via the ionised carboxylate group, and that the side chain of most of the molecules was also in close proximity to the surface. The spectra also indicated that, in contrast, the amine terminus was protonated and relatively far from the surface. Sulfur-containing amino acids also interacted with the silver surface through their sulfur atoms.

  12. Powder processing of hybrid titanium neural electrodes

    NASA Astrophysics Data System (ADS)

    Lopez, Jose Luis, Jr.

    A preliminary investigation into the powder production of a novel hybrid titanium neural electrode for EEG is presented. The rheological behavior of titanium powder suspensions using sodium alginate as a dispersant are examined for optimal slip casting conditions. Electrodes were slip cast and sintered at 950°C for 1 hr, 1000°C for 1, 3, and 6 hrs, and 1050°C for 1 hr. Residual porosities from sintering are characterized using Archimedes' technique and image analysis. The pore network is gel impregnated by submerging the electrodes in electrically conductive gel and placing them in a chamber under vacuum. Gel evaporation of the impregnated electrodes is examined. Electrodes are characterized in the dry and gelled states using impedance spectrometry and compared to a standard silver- silver chloride electrode. Power spectral densities for the sensors in the dry and gelled state are also compared. Residual porosities for the sintered specimens were between 50.59% and 44.81%. Gel evaporation tests show most of the impregnated gel evaporating within 20 min of exposure to atmospheric conditions with prolonged evaporation times for electrodes with higher impregnated gel mass. Impedance measurements of the produced electrodes indicate the low impedance of the hybrid electrodes are due to the increased contact area of the porous electrode. Power spectral densities of the titanium electrode behave similar to a standard silver-silver chloride electrode. Tests suggest the powder processed hybrid titanium electrode's performance is better than current dry contact electrodes and comparable to standard gelled silver-silver chloride electrodes.

  13. On the observation of the roughening transition of organic crystals, growing from solution

    NASA Astrophysics Data System (ADS)

    Jetten, L. A. M. J.; Human, H. J.; Bennema, P.; Van Der Eerden, J. P.

    1984-09-01

    In order to determine whether a face ( hkl) of a crystal is growing above or below the roughening temperature the quantities α hkl and α Rhkl will be used. A method to calculate α Rhkl has been given before. A method to calculate α hkl of a case ( hkl) of a crystal in equilibrium with a saturated solution is presented for the case of a regular solution. The morphology of crystals, growing with faces below and above the roughening temperature is investigated experimentally. The transition from faceted to non-faceted growth, caused by kinetical roughening, which depends on the supersaturation, is investigated for the {110}; and {201¯}; faces of napthalene growing from toluene. The experimental results are in satisfying agreement with the expectations resulting from the calculated values of α hkl and α Rhkl.

  14. Deposition characteristics of copper particles on roughened substrates through kinetic spraying

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Bae, Gyuyeol; Lee, Changhee

    2009-01-01

    In this paper, a systematic study of copper particle deposition behavior on polished and roughened surfaces (aluminum and copper) in kinetic spray process has been performed. The particle deformation behavior was simulated through finite element analysis (FEA) software ABAQUS explicit 6.7-2. The particle-substrate contact time, contact temperature and contact area upon impact have been estimated for smooth and three different roughened substrate cases. Copper powders were deposited on smooth and grit-blasted copper and aluminium substrates and characterized through scanning electron microscopy and Romulus bond strength analyzer. The results indicate that the deformation and the resultant bonding were higher for the roughened substrates than that of smooth. The characteristic factors for bonding are reported and discussed. Thus the substrate roughness appears to be beneficial for the initial deposition efficiency of the kinetic spray process.

  15. Soft-Etching Copper and Silver Electrodes for Significant Device Performance Improvement toward Facile, Cost-Effective, Bottom-Contacted, Organic Field-Effect Transistors.

    PubMed

    Wang, Zongrui; Dong, Huanli; Zou, Ye; Zhao, Qiang; Tan, Jiahui; Liu, Jie; Lu, Xiuqiang; Xiao, Jinchong; Zhang, Qichun; Hu, Wenping

    2016-03-01

    Poor charge injection and transport at the electrode/semiconductor contacts has been so far a severe performance hurdle for bottom-contact bottom-gate (BCBG) organic field-effect transistors (OFETs). Here, we have developed a simple, economic, and effective method to improve the carrier injection efficiency and obtained high-performance devices with low cost and widely used source/drain (S/D) electrodes (Ag/Cu). Through the simple electrode etching process, the work function of the electrodes is more aligned with the semiconductors, which reduces the energy barrier and facilitates the charge injection. Besides, the formation of the thinned electrode edge with desirable micro/nanostructures not only leads to the enlarged contact side area beneficial for the carrier injection but also is in favor of the molecular self-organization for continuous crystal growth at the contact/active channel interface, which is better for the charge injection and transport. These effects give rise to the great reduction of contact resistance and the amazing improvement of the low-cost bottom-contact configuration OFETs performance.

  16. Stress-driven phase transformation and the roughening of solid-solid interfaces.

    PubMed

    Angheluta, L; Jettestuen, E; Mathiesen, J; Renard, F; Jamtveit, B

    2008-03-01

    The application of stress to multiphase solid-liquid systems often results in morphological instabilities. Here we propose a solid-solid phase transformation model for roughening instability in the interface between two porous materials with different porosities under normal compression stresses. This instability is triggered by a finite jump in the free energy density across the interface, and it leads to the formation of fingerlike structures aligned with the principal direction of compaction. The model is proposed as an explanation for the roughening of stylolites-irregular interfaces associated with the compaction of sedimentary rocks that fluctuate about a plane perpendicular to the principal direction of compaction.

  17. Technique eliminates high voltage arcing at electrode-insulator contact area

    NASA Technical Reports Server (NTRS)

    Mealy, G.

    1967-01-01

    Coating the electrode-insulator contact area with silver epoxy conductive paint and forcing the electrode and insulator tightly together into a permanent connection, eliminates electrical arcing in high-voltage electrodes supplying electrical power to vacuum facilities.

  18. Roughening and reflection performance of molybdenum coatings exposed to a high-flux deuterium plasma

    NASA Astrophysics Data System (ADS)

    Eren, B.; Marot, L.; Ryzhkov, I. V.; Lindig, S.; Houben, A.; Wisse, M.; Skoryk, O. O.; Oberkofler, M.; Voitsenya, V. S.; Linsmeier, Ch.; Meyer, E.

    2013-11-01

    Optical diagnostic systems of ITER are foreseen to include metallic, plasma-facing, electromagnetic radiation reflecting components called first mirrors (FMs). Molybdenum coatings are important candidates for these components. Depending on the local plasma parameters of the reactor, the mirrors may be under net erosion or deposition conditions. In this work, we exposed molybdenum coatings to a high-flux deuterium plasma in order to test their roughening limits under erosion conditions. The high energy of deuterium ions (500 eV on average) results in more vigorous roughening of the surface compared with lower energy ions (200 eV). Longer exposure (3 × 1020 ions cm-2) of the 200 eV ions results in only a slightly increased roughness compared with shorter exposure (6.8 × 1019 ions cm-2). Both phenomena match to the theory regarding roughening dynamics of physical sputtering. A comparison of results in this work with previous studies gives support to the hypothesis that roughening is flux and temperature dependent. Partial delamination of the coatings is observed upon exposure at room temperature, but not at an elevated temperature (200 °C). In summary, Mo coatings will remain functional in the ITER environment under the expected conditions. However, changes in the expected conditions such as 500 eV mean energy of impinging charge exchange neutrals or <100 °C surface temperature of the mirrors can lead to gradual or sudden failure of the coatings.

  19. Fabrication and Optimization of ChE/ChO/HRP-AuNPs/c-MWCNTs Based Silver Electrode for Determining Total Cholesterol in Serum.

    PubMed

    Lata, Kusum; Dhull, Vikas; Hooda, Vikas

    2016-01-01

    The developed method used three enzymes comprised of cholesterol esterase, cholesterol oxidase, and peroxidase for fabrication of amperometric biosensor in order to determine total cholesterol in serum samples. Gold nanoparticles (AuNPs) and carboxylated multiwall carbon nanotubes (cMWCNTs) were used to design core of working electrode, having covalently immobilized ChO, ChE, and HRP. Polyacrylamide layer was finally coated on working electrode in order to prevent enzyme leaching. Chemically synthesised Au nanoparticles were subjected to transmission electron microscopy (TEM) for analysing the shape and size of the particles. Working electrode was subjected to FTIR and XRD. The combined action of AuNP and c-MWCNT showed enhancement in electrocatalytic activity at a very low potential of 0.27 V. The pH 7, temperature 40°C, and response time of 20 seconds, respectively, were observed. The biosensor shows a broad linear range from 0.5 mg/dL to 250 mg/dL (0.01 mM-5.83 mM) with minimum detection limit being 0.5 mg/dL (0.01 mM). The biosensor showed reusability of more than 45 times and was stable for 60 days. The biosensor was successfully tested for determining total cholesterol in serum samples amperometrically with no significant interference by serum components. PMID:26885393

  20. In situ SERS and X-ray photoelectron spectroscopy studies on the pH-dependant adsorption of anthraquinone-2-carboxylic acid on silver electrode

    NASA Astrophysics Data System (ADS)

    Li, Dan; Jia, Shaojie; Fodjo, Essy Kouadio; Xu, Hu; Wang, Yuhong; Deng, Wei

    2016-03-01

    In this study, in situ surface-enhanced Raman scattering (SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) are used to investigate the redox reaction and adsorption behavior of anthraquinone-2-carboxylic acid (AQ-2-COOH) on an Ag electrode at different pH values. The obtained results indicate that AQ-2-COOH is adsorbed tilted on the Ag electrode through O-atom of ring carbonyl in a potential range from -0.3 to -0.5 V vs. SCE, but the orientation turns to more tilted orientation with both O-atom of the ring carbonyl and carboxylate group in positive potential region for pH 6.0 and 7.4. However, at pH 10.0, the orientation adopts tilted conformation constantly on the Ag electrode with both O-atom of the anthraquinone ring and carboxylate group in the potential range from -0.3 to -0.5 V vs. SCE or at positive potentials. Moreover, the adsorption behavior of AQ-2-COOH has been further confirmed by AR-XPS on the Ag surface. Proposed reasons for the observed changes in orientation are presented.

  1. Fabrication and Optimization of ChE/ChO/HRP-AuNPs/c-MWCNTs Based Silver Electrode for Determining Total Cholesterol in Serum

    PubMed Central

    Lata, Kusum; Dhull, Vikas

    2016-01-01

    The developed method used three enzymes comprised of cholesterol esterase, cholesterol oxidase, and peroxidase for fabrication of amperometric biosensor in order to determine total cholesterol in serum samples. Gold nanoparticles (AuNPs) and carboxylated multiwall carbon nanotubes (cMWCNTs) were used to design core of working electrode, having covalently immobilized ChO, ChE, and HRP. Polyacrylamide layer was finally coated on working electrode in order to prevent enzyme leaching. Chemically synthesised Au nanoparticles were subjected to transmission electron microscopy (TEM) for analysing the shape and size of the particles. Working electrode was subjected to FTIR and XRD. The combined action of AuNP and c-MWCNT showed enhancement in electrocatalytic activity at a very low potential of 0.27 V. The pH 7, temperature 40°C, and response time of 20 seconds, respectively, were observed. The biosensor shows a broad linear range from 0.5 mg/dL to 250 mg/dL (0.01 mM–5.83 mM) with minimum detection limit being 0.5 mg/dL (0.01 mM). The biosensor showed reusability of more than 45 times and was stable for 60 days. The biosensor was successfully tested for determining total cholesterol in serum samples amperometrically with no significant interference by serum components. PMID:26885393

  2. Two modes of surface roughening during plasma etching of silicon: Role of ionized etch products

    SciTech Connect

    Nakazaki, Nobuya Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

    2014-12-14

    Atomic- or nanometer-scale surface roughening has been investigated during Si etching in inductively coupled Cl{sub 2} plasmas, as a function of rf bias power or ion incident energy E{sub i}, by varying feed gas flow rate, wafer stage temperature, and etching time. The experiments revealed two modes of surface roughening which occur depending on E{sub i}: one is the roughening mode at low E{sub i} < 200–300 eV, where the root-mean-square (rms) roughness of etched surfaces increases with increasing E{sub i}, exhibiting an almost linear increase with time during etching (t < 20 min). The other is the smoothing mode at higher E{sub i}, where the rms surface roughness decreases substantially with E{sub i} down to a low level < 0.4 nm, exhibiting a quasi-steady state after some increase at the initial stage (t < 1 min). Correspondingly, two different behaviors depending on E{sub i} were also observed in the etch rate versus √(E{sub i}) curve, and in the evolution of the power spectral density distribution of surfaces. Such changes from the roughening to smoothing modes with increasing E{sub i} were found to correspond to changes in the predominant ion flux from feed gas ions Cl{sub x}{sup +} to ionized etch products SiCl{sub x}{sup +} caused by the increased etch rates at increased E{sub i}, in view of the results of several plasma diagnostics. Possible mechanisms for the formation and evolution of surface roughness during plasma etching are discussed with the help of Monte Carlo simulations of the surface feature evolution and classical molecular dynamics simulations of etch fundamentals, including stochastic roughening and effects of ion reflection and etch inhibitors.

  3. Roughening transition in nanoporous hydrogenated amorphous germanium: Roughness correlation to film stress

    NASA Astrophysics Data System (ADS)

    Carroll, M. S.; Verley, J. C.; Sheng, J. J.; Banks, J.

    2007-03-01

    Hydrogenated amorphous germanium (a-Ge:H) is a material of interest for optoelectronic applications such as solar cells and radiation detectors because of the material's potential to extend the wavelength sensitivity of hydrogenated amorphous silicon (a-Si:H). An increase in porosity is observed in amorphous germanium compared to a-Si :H, and this increase in porosity has been correlated with a degradation of the electrical performance. Improved understanding of the mechanisms of porous formation in a-Ge :H films is therefore desirable in order to better control it. In this paper we describe a correlation between film stress and surface roughness, which evolves with increasing thickness of a-Ge :H. A roughening transition from planar two-dimensional growth to three-dimensional growth at a critical thickness less than 800Å results in a network of needlelike nanotrench cavities which stretch from the transition thickness to the surface in films up to 4000Å thick. Surface roughness measurements by atomic force microscope and transmission electron microscopy indicate that the transition is abrupt and that the roughness increases linearly after the transition thickness. The roughening transition thickness is, furthermore, found to correlate with the maxima of the integrated compressive stress. The compressive stress is reduced after this transition thickness due to the incorporation of nanovoids into the film that introduce tensile stress as the islands coalesce together. The roughening transition behavior is similar to that found in a general class of Volmer-Weber mode thin film deposition (e.g., Cu, Ag, and nonhydrogenated amorphous silicon), which offers additional insight into the underlying mechanisms of the stress and roughening in these a-Ge :H films. The suppression of the roughening transition by changing the kinetics of the deposition rates (e.g., slowing the deposition rate with a weak sputtering bias) is also observed and discussed.

  4. Large silver-cadmium technology program

    NASA Technical Reports Server (NTRS)

    Charlip, S.; Lerner, S.

    1971-01-01

    The effects of varying cell design on operation factors on the electrochemical performance of sealed, silver-cadmium cells were determined. A factorial experiment was conducted for all test cells constructed with organic separators. Three operating factors were evaluated: temperature, depth of discharge, and charge rate. The six construction factors considered were separator, absorber, electrolyte quantity, cadmium electrode type, cadmium-to-silver ratio, and auxiliary electrode. Test cells of 4 ampere-hour capacity were fabricated and cycled. The best performing cells, on a 94 minute orbit, at 40% depth of discharge, were those containing silver-treated fibrous sausage casings as the separator, and Teflon-ated, pressed cadmium electrodes. Cycling data of cells with inorganic separators (Astroset) are given. Best performance was shown by cells with nonwoven nylon absorbers. Rigid inorganic separators provided the best barrier to silver migration.

  5. Electrode for a lithium cell

    DOEpatents

    Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

    2008-10-14

    This invention relates to a positive electrode for an electrochemical cell or battery, and to an electrochemical cell or battery; the invention relates more specifically to a positive electrode for a non-aqueous lithium cell or battery when the electrode is used therein. The positive electrode includes a composite metal oxide containing AgV.sub.3O.sub.8 as one component and one or more other components consisting of LiV.sub.3O.sub.8, Ag.sub.2V.sub.4O.sub.11, MnO.sub.2, CF.sub.x, AgF or Ag.sub.2O to increase the energy density of the cell, optionally in the presence of silver powder and/or silver foil to assist in current collection at the electrode and to improve the power capability of the cell or battery.

  6. Determination of Silver(I) by Differential Pulse Voltammetry Using a Glassy Carbon Electrode Modified with Synthesized N-(2-Aminoethyl)-4,4′-Bipyridine

    PubMed Central

    Radulescu, Maria-Cristina; Chira, Ana; Radulescu, Medeea; Bucur, Bogdan; Bucur, Madalina Petruta; Radu, Gabriel Lucian

    2010-01-01

    A new modified glassy carbon electrode (GCE) based on a synthesized N-(2-aminoethyl)-4,4′-bipyridine (ABP) was developed for the determination of Ag(I) by differential pulse voltammetry (DPV). ABP was covalently immobilized on GC electrodes surface using 4-nitrobenzendiazonium (4-NBD) and glutaraldehyde (GA). The Ag(I) ions were preconcentrated by chemical interaction with bipyridine under a negative potential (−0.6 V); then the reduced ions were oxidized by differential pulse voltammetry and a peak was observed at 0.34 V. The calibration curve was linear in the concentration range from 0.05 μM to 1 μM Ag(I) with a detection limit of 0.025 μM and RSD = 3.6%, for 0.4 μM Ag(I). The presence of several common ions in more than 125-fold excess had no effect on the determination of Ag(I). The developed sensor was applied to the determination of Ag(I) in water samples using a standard addition method. PMID:22163530

  7. Good Thermal Stability, High Permittivity, Low Dielectric Loss and Chemical Compatibility with Silver Electrodes of Low-Fired BaTiO3-Bi(Cu0.75W0.25)O3 Ceramics

    NASA Astrophysics Data System (ADS)

    Chen, Xiuli; Ma, Dandan; Chen, Jie; Huang, Guisheng; Zhou, Huanfu

    2016-09-01

    (1 - x)BaTiO3-xBi(Cu0.75W0.25)O3 [(1 - x)BT-xBCW, 0 ≤ x ≤ 0.04] perovskite solid solutions ceramics of an X8R-type multilayer ceramic capacitor with a low sintering temperature (900°C) were synthesized by a conventional solid state reaction technique. Raman spectra and x-ray diffraction analysis demonstrated that a systematically structural evolution from a tetragonal phase to a pseudo-cubic phase appeared near 0.03 < x < 0.04. X-ray photoelectron analysis confirmed the existence of Cu+/Cu2+ mixed-valent structure in 0.96BT-0.04BCW ceramics. 0.96BT-0.04BCW ceramics sintered at 900°C showed excellent temperature stability of permittivity (Δɛ/ɛ 25°C ≤ ±15%) and retained good dielectric properties (relative permittivity ˜1450 and dielectric loss ≤2%) over a wide temperature range from 25°C to 150°C at 1 MHz. Especially, 0.96BT-0.04BCW dielectrics have good compatibility with silver powders. Dielectric properties and electrode compatibility suggest that the developed materials can be used in low temperature co-fired multilayer capacitor applications.

  8. A view of aqueous electrochemical carbon dioxide reduction to formate at indium electrodes, and the reversible electrodeposition of silver in ionic liquids through the lens of fundamental surface science

    NASA Astrophysics Data System (ADS)

    Detweiler, Zachary M.

    Two systems were studied using in situ measurement techniques, demonstrating the importance of creative experimental design. The electroreduction of CO2 at heterogeneous indium electrodes in aqueous solution was analyzed by cyclic voltammetry. Bulk electrolyses showed that increased indium oxide presence prior to electrolysis improved the Faradaic efficiency of CO 2 reduction to formate in 0.5 M K2SO2 aqueous solutions at a pH of 4.4. In order to more accurately assign speciation at the electrode surface ex situ O2 and H2O dosing of metallic indium under UHV was studied with XPS, HREELS and TPD. Ambient pressure XPS showed that the ratio of oxide to hydroxide at the indium interface is strongly dependent on the partial pressure of water; decreasing as P(H2O) increases. Using this information, a qualitative picture of the indium interface could be generated. In situ ATR-FTIR with an indium thin film as the working electrode showed that bulk oxide quickly reduces with applied potential, but an interfacial oxide is still present at high reductive overpotential. Additionally, an adsorbed carbonate at the thin film interface was observed upon introducing CO 2 to the cell. The implication of a surface bound carbonate as the CO 2 reduction intermediate draws on a mechanism that has not previously been discussed in the electrochemical reduction of CO2. The previous study of this mechanism from Ficscher-Tropsch literature helps to predict the further reduced products found at more electropositive metals, such as copper or magnesium, the latter of which is described here. Additionaly described here is a series of ILs that were employed as electrolyte for reversible silver deposition. BMIM N(TfO)2 was found to be the most promising of those studied, intrinsically giving a more uniform deposit that was bright and reversible. Deposit formation was studied using SEM and EDX as a function of deposition potential and deposition time. In situ reflectometry was employed to get a

  9. Improved conductive paste secures biomedical electrodes

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Nontoxic paste consisting of a dispersion of graphite or silver granules in a mixture of polyvinylpyrolidone and diluted glycerol secures biomedical electrodes to human skin. Silver paste has a high electrical conductivity and forms a bond between metal and moist or dry skin.

  10. Vibrational Sum Frequency Study of the Influence of Water-Ionic Liquid Mixtures in the CO2 Electroreduction on Silver Electrodes

    NASA Astrophysics Data System (ADS)

    Garcia Rey, Natalia; Dlott, Dana

    2015-06-01

    Understand the molecular dynamics on buried electrodes under electrochemical transformations is of significant interest. There is a big gap of knowledge in the CO2 electroreduction mechanism due to the limitations to access and probe the liquid-metal interfaces [1,2]. Vibrational Sum Frequency Spectroscopy (VSFS) is a non-invasive and surface sensitive technique, with molecular level detection that can be used to probe electrochemical reactions occurring on the electrolyte-electrode interface [2]. We observed the CO2 electroreduction to CO in ionic liquids (ILs) on poly Ag using VSFS synchronized with cyclic voltammetry. In order to follow the CO2 reaction in situ on the ionic liquid-Ag interface; the CO, CO2 and imidazolium vibrational modes (resonant SFS) were monitored as a function of potential. We identified at which potential the CO was produced and how the EMIM-BF4 played an important role in the electron transfer to the CO2, lowering the CO2- energy barrier. A new approach to reveal the double layer dynamics to the electrostatic environment is presented by the study of the nonresonant sum frequency intensity as a function of the applied potential. By this method, we studied the influence of water-ionic liquid mixtures in the CO2 electroreduction on Ag electrode. We observed a shift to lower potentials in the CO2 electroreduction in water-ILs electrolyte. Previous studies in gas diffusion fuel cells have shown the CO2 electroreduction in a water-imidazolium-based ILs on Ag nanoparticles at lower overpotential [3]. Our VSFS study helps to understand the fundamental electrochemical mechanism, showing how the ILs structural transition influences the CO2 electroreduction. [1] Polyansky, D. E.; Electroreduction of Carbon Dioxide, 2014, Encyclopedia of Applied Electrochemistry, Springer New York, pag 431-437. [2] Bain, C. D.; J. Chem. Soc., Faraday Trans., 1995, 91, 1281. [3] Rosen, B. A. et al; Science, 2011, 334 (6056), 643. Rosen, B. A. et al.; J. electrochem

  11. Intrinsic anomalous surface roughening of TiN films deposited by reactive sputtering

    SciTech Connect

    Auger, M. A.; Vazquez, L.; Sanchez, O.; Cuerno, R.; Castro, M.; Jergel, M.

    2006-01-15

    We study surface kinetic roughening of TiN films grown on Si(100) substrates by dc reactive sputtering. The surface morphology of films deposited for different growth times under the same experimental conditions were analyzed by atomic force microscopy. The TiN films exhibit intrinsic anomalous scaling and multiscaling. The film kinetic roughening is characterized by a set of local exponent values {alpha}{sub loc}=1.0 and {beta}{sub loc}=0.39, and global exponent values {alpha}=1.7 and {beta}=0.67, with a coarsening exponent of 1/z=0.39. These properties are correlated to the local height-difference distribution function obeying power-law statistics. We associate this intrinsic anomalous scaling with the instability due to nonlocal shadowing effects that take place during thin-film growth by sputtering.

  12. Reduction of surface roughening due to copper contamination prior to ultra-thin gate oxidation

    NASA Astrophysics Data System (ADS)

    Peterson, Charles A.; Vermeire, Bert; Sarid, Dror; Parks, Harold G.

    2001-09-01

    Roughening of the polished side of a silicon wafer caused by copper contamination present on the unpolished side of the wafer was quantified by tapping-mode atomic force microscopy (AFM). The copper contamination was introduced via a contaminated buffered hydrochloric acid solution on the unpolished side of the silicon wafer while the polished side was protected. The protection was then removed, and the wafer placed in a clean HF solution. As a result, the copper on the unpolished side catalyzed electrochemical dissolution of the polished side of the silicon. Power spectral density analysis of hundreds of AFM images showed a 10-fold increase in surface roughness with features between 30 and 300 nm in diameter. Time-dependant dielectric breakdown measurements showed a significant decrease in oxide quality in these wafers. However, the introduction of HCl to the HF solution significantly reduced the roughening process.

  13. Atomic diffusion on vicinal surfaces: step roughening impact on step permeability

    NASA Astrophysics Data System (ADS)

    Ranguelov, B.; Michailov, M.

    2014-12-01

    The problem of mass transport in material science for systems with reduced dimensionality holds special academic and technological attention since the fine diffusion control of adatoms could initiate exotic nanoscale patterning at epitaxial interfaces. The present study brings out important details of the atomic diffusion mechanisms on vicinal surfaces, accounting for the subtle competition between an external field imposed on the migrating adatoms and the roughening of the steps bordering the atomic terraces. The computational model reveals a temperature gap for breakdown of step permeability in the vicinity of the step roughening transition and sheds light on recently observed experimental results for atomic step dynamics on Si surfaces. The present study also demonstrates the extended capability of atomistic models in computer simulations to unravel simultaneous effects, to distinguish between them, and finally to assess their specific contribution to experimentally observed complex physical phenomena.

  14. Influence of Ice Particle Surface Roughening on the Global Cloud Radiative Effect

    NASA Technical Reports Server (NTRS)

    Yi, Bingqi; Yang, Ping; Baum, Bryan A.; LEcuyer, Tristan; Oreopoulos, Lazaros; Mlawer, Eli J.; Heymsfield, Andrew J.; Liou, Kuo-Nan

    2013-01-01

    Ice clouds influence the climate system by changing the radiation budget and large-scale circulation. Therefore, climate models need to have an accurate representation of ice clouds and their radiative effects. In this paper, new broadband parameterizations for ice cloud bulk scattering properties are developed for severely roughened ice particles. The parameterizations are based on a general habit mixture that includes nine habits (droxtals, hollow/solid columns, plates, solid/hollow bullet rosettes, aggregate of solid columns, and small/large aggregates of plates). The scattering properties for these individual habits incorporate recent advances in light-scattering computations. The influence of ice particle surface roughness on the ice cloud radiative effect is determined through simulations with the Fu-Liou and the GCM version of the Rapid Radiative Transfer Model (RRTMG) codes and the National Center for Atmospheric Research Community Atmosphere Model (CAM, version 5.1). The differences in shortwave (SW) and longwave (LW) radiative effect at both the top of the atmosphere and the surface are determined for smooth and severely roughened ice particles. While the influence of particle roughening on the single-scattering properties is negligible in the LW, the results indicate that ice crystal roughness can change the SW forcing locally by more than 10 W m(exp -2) over a range of effective diameters. The global-averaged SW cloud radiative effect due to ice particle surface roughness is estimated to be roughly 1-2 W m(exp -2). The CAM results indicate that ice particle roughening can result in a large regional SW radiative effect and a small but nonnegligible increase in the global LW cloud radiative effect.

  15. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na{sub 2}O added as NAOH instead of Na{sub 2}CO{sub 3} to avoid severe foaming due to CO{sub 2} evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  16. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na[sub 2]O added as NAOH instead of Na[sub 2]CO[sub 3] to avoid severe foaming due to CO[sub 2] evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  17. Self-organized criticality in proteins: Hydropathic roughening profiles of G-protein-coupled receptors

    NASA Astrophysics Data System (ADS)

    Phillips, J. C.

    2013-03-01

    Proteins appear to be the most dramatic natural example of self-organized criticality (SOC), a concept that explains many otherwise apparently unlikely phenomena. Protein conformational functionality is often dominated by long-range hydrophobic or hydrophilic interactions which both drive protein compaction and mediate protein-protein interactions. Superfamily transmembrane G-protein-coupled receptors (GPCRs) are the largest family of proteins in the human genome; their amino acid sequences form the largest database for protein-membrane interactions. While there are now structural data on the heptad transmembrane structures of representatives of several heptad families, here we show how fresh insights into global and some local chemical trends in GPCR properties can be obtained accurately from sequences alone, especially by algebraically separating the extracellular and cytoplasmic loops from transmembrane segments. The global mediation of long-range water-protein interactions occurs in conjunction with modulation of these interactions by roughened interfaces. Hydropathic roughening profiles are defined here solely in terms of amino acid sequences, and knowledge of protein coordinates is not required. Roughening profiles both for GPCR and some simpler protein families display accurate and transparent connections to protein functionality, and identify natural length scales for protein functionality.

  18. Molecular-Orientation-Induced Rapid Roughening and Morphology Transition in Organic Semiconductor Thin-Film Growth

    NASA Astrophysics Data System (ADS)

    Yang, Junliang; Yim, Sanggyu; Jones, Tim S.

    2015-03-01

    We study the roughening process and morphology transition of organic semiconductor thin film induced by molecular orientation in the model of molecular semiconductor copper hexadecafluorophthalocyanine (F16CuPc) using both experiment and simulation. The growth behaviour of F16CuPc thin film with the thickness, D, on SiO2 substrate takes on two processes divided by a critical thickness: (1) D <= 40 nm, F16CuPc thin films are composed of uniform caterpillar-like crystals. The kinetic roughening is confirmed during this growth, which is successfully analyzed by Kardar-Parisi-Zhang (KPZ) model with scaling exponents α = 0.71 +/- 0.12, β = 0.36 +/- 0.03, and 1/z = 0.39 +/- 0.12; (2) D > 40 nm, nanobelt crystals are formed gradually on the caterpillar-like crystal surface and the film growth shows anomalous growth behaviour. These new growth behaviours with two processes result from the gradual change of molecular orientation and the formation of grain boundaries, which conversely induce new molecular orientation, rapid roughening process, and the formation of nanobelt crystals.

  19. Molecular-Orientation-Induced Rapid Roughening and Morphology Transition in Organic Semiconductor Thin-Film Growth

    PubMed Central

    Yang, Junliang; Yim, Sanggyu; Jones, Tim S.

    2015-01-01

    We study the roughening process and morphology transition of organic semiconductor thin film induced by molecular orientation in the model of molecular semiconductor copper hexadecafluorophthalocyanine (F16CuPc) using both experiment and simulation. The growth behaviour of F16CuPc thin film with the thickness, D, on SiO2 substrate takes on two processes divided by a critical thickness: (1) D ≤ 40 nm, F16CuPc thin films are composed of uniform caterpillar-like crystals. The kinetic roughening is confirmed during this growth, which is successfully analyzed by Kardar-Parisi-Zhang (KPZ) model with scaling exponents α = 0.71 ± 0.12, β = 0.36 ± 0.03, and 1/z = 0.39 ± 0.12; (2) D > 40 nm, nanobelt crystals are formed gradually on the caterpillar-like crystal surface and the film growth shows anomalous growth behaviour. These new growth behaviours with two processes result from the gradual change of molecular orientation and the formation of grain boundaries, which conversely induce new molecular orientation, rapid roughening process, and the formation of nanobelt crystals. PMID:25801646

  20. Hybrid RANS/LES of turbulent flow in a rotating rib-roughened channel

    NASA Astrophysics Data System (ADS)

    Xun, Qian-Qiu; Wang, Bing-Chen

    2016-07-01

    In this paper, we investigate the effect of the Coriolis force on the flow field in a rib-roughened channel subjected to either clockwise or counter-clockwise system rotation using hybrid RANS/LES based on wall modelling. A simplified dynamic forcing scheme incorporating backscatter is proposed for the hybrid simulation approach. The flow is characterized by a Reynolds number of Re = 1.5 × 104 and a rotation number Ro ranging from -0.6 to 0.6. The mean flow speed and turbulence level near the roughened wall are enhanced under counter-clockwise rotation and suppressed under clockwise rotation. The Coriolis force significantly influences the stability of the wall shear layer and the free shear layers generated by the ribs. Consequently, it is interesting to observe that the classification of the roughness type relies not only on the pitch ratio, but also on the rotation number in the context of rotating rib-roughened flows. In order to validate the present hybrid approach, the first- and second-order statistical moments of the velocity field obtained from the simulations are thoroughly compared with the available laboratory measurement data.

  1. Hierarchically roughened microplatelets enhance the strength and ductility of nacre-inspired composites.

    PubMed

    Niebel, Tobias P; Carnelli, Davide; Binelli, Marco R; Libanori, Rafael; Studart, André R

    2016-07-01

    Rough interfaces featuring nanoscale asperities are known to play a major role in the mechanics of nacre. Transferring this concept to artificial bioinspired composites requires a detailed understanding about the effect of the surface topography of reinforcing elements on the mechanical performance of such materials. To gain further insights into the effect of asperity size, hierarchy and coverage on the mechanics of nacre-inspired composites, we decorate alumina microplatelets with silica nanoparticles of selected sizes and use the resulting roughened platelets as reinforcing elements (15vol%) in a commercial epoxy matrix. For a single layer of silica nanoparticles on the platelet surface, increased ultimate strain and toughness are obtained with a large roughening particle size of 250nm. On the contrary, strength and stiffness are enhanced by decreasing the size of asperities using 22nm silica particles. By combining particles of two different sizes (100nm and 22nm) in a hierarchical fashion, we are able to improve stiffness and strength of platelet-reinforced polymers while maintaining high ultimate strain and toughness. Our results indicate that carefully designed hierarchically roughened interfaces lead to a more homogeneous stress distribution within the polymer matrix between the stiff reinforcing elements. By enabling the deformation of a larger fraction of the polymer matrix, this design concept improves the mechanical response of bioinspired composites and can possibly also be exploited to enhance the performance of conventional fiber-reinforced polymers. PMID:26926989

  2. Higher-efficiency photoelectrochemical electrodes of titanium dioxide-based nanoarrays sensitized simultaneously with plasmonic silver nanoparticles and multiple metal sulfides photosensitizers

    NASA Astrophysics Data System (ADS)

    Guo, Keying; Liu, Zhifeng; Han, Jianhua; Zhang, Xueqi; Li, Yajun; Hong, Tiantian; Zhou, Cailou

    2015-07-01

    This paper describes a novel design of high-efficiency photoelectrochemical water splitting electrode, i.e., ordered TiO2 nanorod arrays (NRs) sensitized simultaneously with noble metal (Ag), binary metal sulfides (Ag2S) and ternary metal sulfides (Ag3CuS2) multiple photosensitizers for the first time. The TiO2/Ag/Ag2S/Ag3CuS2 NRs heterostructure is successfully synthesized through successive ion layer adsorption and reaction (SILAR) and a simple ion-exchange process based on ionic reaction mechanism. On the basis of an optimal quantity of Ag, Ag2S and Ag3CuS2 nanoparticles, such TiO2/Ag/Ag2S/Ag3CuS2 NRs exhibit a higher photoelectrochemical activity ever reported for TiO2-based nanoarrays in PEC water splitting, the photocurrent density is up to 9.82 mA cm-2 at 0.47 V versus Ag/AgCl, respectively. This novel architecture is able to increase electron collection efficiency and suppress carrier recombination via (i) a higher efficiency of light-harvesting through these multiple photosensitizers (Ag, Ag2S and Ag3CuS2); (ii) the efficient separation of photo-induced electrons and holes due to the direct electrical pathways; (iii) the surface plasmon resonance (SPR) effect of Ag nanoparticles, which enhances the efficient charge separation and high carrier mobility. This work is useful to explore feasible routes to further enhance the performance of oxide semiconductors for PEC water splitting to produce clean H2 energy.

  3. Frequency response measurements in battery electrodes

    NASA Technical Reports Server (NTRS)

    Thomas, Daniel L.

    1992-01-01

    Electrical impedance spectroscopy was used to investigate the behavior of porous zinc, silver, cadmium, and nickel electrodes. State of charge could be correlated with impedance data for all but the nickel electrodes. State of health was correlated with impedance data for two AgZn cells, one apparently good and the other bad. The impedance data was fit to equivalent circuit models.

  4. Silver Doped Titanium Dioxide Humidity Sensor

    NASA Astrophysics Data System (ADS)

    Hooshiar Zare, Ali; Mohammadi, Somayye

    2011-02-01

    The effect of silver doping on the sensitivity, dynamic range and the response time of a titanium dioxide-based resistive humidity sensor is studied. Sample pallets were prepared by sintering the dry pressed samples at 900°C in air. Silver was added to the ceramic raw material in the form of AgNO3 which was decomposed during the sintering process. Large area silver electrodes were deposited on the sintered disks by paste printing. The resistance and the response time of the various pallets containing different additive levels were measured at relative humidity range of 4-100%. Silver doping, substantially increased the sensitivity to the ambient humidity. Moreover, it resulted in faster responses; the response time of the silver added pallets were about four times shorter than the pure ones.

  5. Kinetic Roughening with Surface Diffusion: Crossover from Ramified Aggregates to Continuous Films on Liquid Surfaces

    NASA Astrophysics Data System (ADS)

    Lv, Neng; Zhang, Chu-Hang; Yang, Bo; Pan, Qi-Fa; Ye, Gao-Xiang

    2012-09-01

    Ramified iron aggregates are fabricated on silicone oil surface by thermal evaporation method at room temperature and the crossover from ramified aggregates to continuous films is studied by atomic force microscopy. It is shown that the aggregates are composed of numerous granules with the average diameter around 34 nm. The dynamic scaling analysis shows that the growth exponent β = 0.23 ± 0.02 and the roughness exponent α evolves from 0.65 to 0.42 with the nominal film thickness, indicating a roughening behavior transfer may exist during the growth process. The physical interpretation for the scaling behavior is presented.

  6. Anomalous scaling behavior and surface roughening in molecular thin-film deposition

    SciTech Connect

    Yim, S.; Jones, T. S.

    2006-04-15

    The thin film growth dynamics of a molecular semiconductor, free-base phthalocyanine (H{sub 2}Pc), deposited by organic molecular beam deposition, has been studied by atomic force microscopy (AFM) and height difference correlation function (HDCF) analysis. The measured dynamic scaling components ({alpha}{sub loc}=0.61{+-}0.12, {beta}=1.02{+-}0.08, and 1/z=0.72{+-}0.13) are consistent with rapid surface roughening and anomalous scaling behavior. A detailed analysis of AFM images and simple growth models suggest that this behavior arises from the pronounced upward growth of crystalline H{sub 2}Pc mounds during the initial stages of thin film growth.

  7. Microtitrimetry by differential electrolytic potentiometry using metallic electrodes and nanomaterials modified metallic electrodes

    NASA Astrophysics Data System (ADS)

    Amro, Abdulaziz Nabil

    For the first time silver wire electrodes have been coated with carbon nanotubes using floating catalyst chemical vapor deposition (CVD) method. The production of CNTs has been conducted in a horizontal tubular reactor. Acetylene gas was used as a carbon source. Ferrocene has been used as a catalyst precursor for the growth of CNT. Different parameters have been optimized to get a high yield of CNTs and ensure their growth on the silver electrodes using univariate method. The parameters studied include the hydrogen flow rate, acetylene flow rate, temperature of the furnace, time of the reaction and the location of the electrodes in the reactor tube. The optimum conditions for those parameters were: for hydrogen and acetylene, the flow rates were 25 mL /min and 75 mL / min respectively. The furnace temperature was found to be 700 °C and the reaction time was 15 minutes. Regarding the location of the silver wires it should be located in the first 10 cm of the front side of the tube. Scanning electron microscopy (SEM) and transition electron microscopy (TEM) have been used to characterize carbon on silver electrodes. According to the experimental results, TEM figures show that CNT produced on Silver wire is multiwall carbon nanotubes MWCNT. Silver electrodes either pure or coated with CNT were used as indicating systems in micro titration using both dc differential electrolytic potentiometry (DEP) and mark-space bias DEP techniques. All types of titrimetric reactions were investigated using different types of electrodes like Pt and gold for oxidation reduction titrations, antimony electrodes for acid base titrations, silver electrodes for precipitation titrations in addition to Ag-CNT electrodes. End points at volumes of 1 microL were determined. Different parameters were optimized like the current density, the percentage bias, the volume of the sample and the concentrations of the reactants. Microtitrimetry has been applied on several types of analytes; Ferrous

  8. Biomedical engineering tasks. [electrode development for electrocardiography and electroencephalography

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Electrocardiographic and vectorcardiographic bioinstrumentation work centered on the development of a new electrode system harness for Project Skylab. Evaluation of several silver electrode configurations proved superior impedance voltage performance for silver/silver chloride electrodes mounted flush by using a paste adhesive. A portable ECG processor has been designed and a breadboard unit has been built to sample ECG input data at a rate of 500 samples per second for arrhythmia detection. A small real time display driver program has been developed for statistical analysis on selected QPS features. Engineering work on a sleep monitoring cap assembly continued.

  9. Kinetic Roughening and Energetics of Tetragonal Lysozyme Crystal Growth: A Preliminary Atomic Force Microscopy Investigation

    NASA Technical Reports Server (NTRS)

    Gorti, Sridhar; Forsythe, Elizabeth L.; Pusey, Marc L.

    2004-01-01

    We examined particulars of crystal growth from measurements obtained at both microscopic and molecular levels. The crystal growth measurements performed at the microscopic level are well characterized by a model that balances the flux of macromolecules towards the crystal surface with the flux of the crystal surface. Numerical evaluation of model with measurements of crystal growth, in time, provided accurate estimates for the average growth velocities. Growth velocities thus obtained were also interpreted using well-established phenomenological theories. Moreover, we find that microscopic measurements of growth velocity measurements obtained as a function of temperature best characterizes changes in crystal growth modes, when present. We also examined the possibility of detecting a change in crystal growth modes at the molecular level using atomic force microscopy, AFM. From preliminary AFM measurements performed at various supersaturations, we find that magnitude of surface height fluctuations, h(x), increases with supersaturation. Further examination of surface height fluctuations using methods established for fluctuation spectroscopy also enabled the discovery of the existence of a characteristic length, c, which may possibly determine the mode of crystal growth. Although the results are preliminary, we establish the non- critical divergence of 5 and the root-mean-square (rms) magnitude of height-height fluctuations as the kinetic roughening transition temperatures are approached. Moreover, we also examine approximate models for interpreting the non-critical behavior of both 6 and rms magnitude of height-height fluctuations, as the solution supersaturation is increased towards the kinetic roughening supersaturation.

  10. Friction Factor for Flow in Rectangular Ducts with One Side Rib-Roughened

    NASA Technical Reports Server (NTRS)

    Youn, B.; Yuen, C.; Mills, A. F.

    1994-01-01

    Numerical simulations of incompressible turbulent flow through rectangular ducts with one side rib-roughened were performed to determine pressure drop. The "PHOENICS " software package was used for the computations, which required provision of a wall function for transverse rib-roughened surfaces. The present study was conducted in the range of 10(exp 5) less than or equal to Reynolds number less than or equal to 10(exp 7), 0.01 less than or equal to rib height to hydraulic diameter ratio less than or equal to 0.04, 10 less than or equal to pitch to rib height ratio less than or equal to 40. Using the numerical results, friction factor charts for various aspect ratios were generated. The numerical results agreed well with experimental data that was obtained for 10(exp 5) less than Reynolds less than 2 x 10(exp 5). In addition, a scheme for predicting friction factor using existing correlations for smooth and rough walls was developed.

  11. Morphological switching in synchrotron-radiation-excited Ge homoepitaxy: Transition from kinetic roughening to smoothing

    SciTech Connect

    Akazawa, Housei

    2005-05-15

    The surface morphology of Ge films during GeH{sub 4}-source molecular beam epitaxy on a Ge(100) substrate is dramatically changed through irradiation with synchrotron radiation (h{nu}>100 eV). At temperatures below 300 deg. C, a two-dimensionally flat film continues to grow with the surface tightly passivated by a GeH{sub x} hydride layer. At temperatures above 350 deg. C, dangling bonds are partially terminated with hydrogen atoms while Ge adatoms are highly mobile, resulting in a nonuniform nucleation that creates the islands. Small islands merge into a few-hundred-nanometer-tall islands surrounded by the (113)-face sidewalls. This kinetic roughening continues until the nucleation on the (001) plane ceases due to the buildup of the GeH{sub x} layer. Once the surface free energy is minimized by the hydrogen termination, flattening of the islands proceeds to reduce the chemical potential of the system. The valleys between the islands are preferentially filled, and the film is eventually converted into a smooth epilayer with no memory of the initial roughening.

  12. Silver cyanide

    Integrated Risk Information System (IRIS)

    Silver cyanide ; CASRN 506 - 64 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  13. New electrosurgical ball electrode with nonstick properties

    NASA Astrophysics Data System (ADS)

    Rondinone, Joseph; Brassell, James; Miller, Scott A., III; Thorne, Jonathan O.; Rondinone, David M.; Safabash, Jason; Vega, Felix

    1998-04-01

    A new electrosurgical ball electrode (SilverBulletTM) has been developed for applying radiofrequency (RF) energy to fuse biological and other materials to tissue surfaces. Specifically, the electrode was developed for use in conjunction with the Fusion Medical Technologies, Inc. gelatin patch (RapiSealTM) for use in pulmonary surgery to seal air leaks, and in solid abdominal organ surgeries to provide hemostatic tamponade. The new electrode allows for the application of RF energy in contact mode without the problems of the electrode sticking to the gelatin patch or the underlying tissue. Designed for use with commercially available electrosurgical handpieces, the electrode consists of a stainless steel connector that fits into the hand- piece, and an electrode assembly made from silver that includes a shank region, and a tip extension extending distally from the shank region. The distal tip of the tip extension is rounded and has a length of about 10 mm. The uniqueness of this electrode is the shank region which has a cross sectional area that is larger than the tip extension. The shank region acts as a heat sink to draw away heat from the tip extension while the tip extension itself remains sufficiently small to access desired target sites and display the desired energy transfer properties. In addition to the physical design, the use of silver as the core element provides a material with high electrical and thermal conductivities. The bulk of the electrode is appropriately insulated.

  14. Electrodes for long-term esophageal electrocardiography.

    PubMed

    Niederhauser, Thomas; Haeberlin, Andreas; Marisa, Thanks; Jungo, Michael; Goette, Josef; Jacomet, Marcel; Abacherli, Roger; Vogel, Rolf

    2013-09-01

    The emerging application of long-term and high-quality ECG recording requires alternative electrodes to improve the signal quality and recording capability of surface skin electrodes. The esophageal ECG has the potential to overcome these limitations but necessitates novel recorder and lead designs. The electrode material is of particular interest, since the material has to ensure conflicting requirements like excellent biopotential recording properties and inertness. To this end, novel electrode materials like PEDOT and silver-PDMS as well as established electrode materials such as stainless steel, platinum, gold, iridium oxide, titanium nitride, and glassy carbon were investigated by long-term electrochemical impedance spectroscopy and model-based signal analysis using the derived in vitro interfacial properties in conjunction with a dedicated ECG amplifier. The results of this novel approach show that titanium nitride and iridium oxide featuring microstructured surfaces did not degrade when exposed to artificial acidic saliva. These materials provide low electrode potential drifts and insignificant signal distortion superior to surface skin electrodes making them compatible with accepted standards for ambulatory ECG. They are superior to the noble and polarizable metals such as platinum, silver, and gold that induced more signal distortions and are superior to esophageal stainless steel electrodes that corrode in artificial saliva. The study provides rigorous criteria for the selection of electrode materials for prolonged ECG recording by combining long-term in vitro electrode material properties with ECG signal quality assessment.

  15. Fabrication and testing of silver-hydrogen cells

    NASA Technical Reports Server (NTRS)

    Debicarri, D. J.; Charkey, A.

    1978-01-01

    Silver electrodes containing various additives were fabricated and tested in single electrode cells in order to improve the electrochemical utilization of sintered silver cathodes in Ag-H2 aerospace batteries. A standard stack arrangement was used which featured a NASA-developed organic-inorganic separator. All cells were cycled in a regime designed to remove 75% of the cells nominal capacity based on 3.3 gms/AHr Ag utilization. In cases where performance degradation was observed, the main feature mode appeared to be corrosion of either the expanded silver current collector or the connection between the silver electrode and the electrode tab. Promising silver electrodes from single electrode studies were used in the construction of 35 AHr Ag-H2 cells. Two such cells were constructed and installed in heavy walled pressure vessels for testing. Based on the data obtained from all cells tested during the program, four lightweight 35 AHr cells were fabricated. During acceptance testing these cells yielded an average gravimetric energy density of 30 WHr/1b.

  16. Osteogenesis of bone marrow mesenchymal stem cells on strontium-substituted nano-hydroxyapatite coated roughened titanium surfaces

    PubMed Central

    Yang, Hua-Wei; Lin, Mao-Han; Xu, Yuan-Zhi; Shang, Guang-Wei; Wang, Rao-Rao; Chen, Kai

    2015-01-01

    Objective: To investigate osteogenesis of bone marrow mesenchymal stem cells (BMSCs) on strontium-substituted nano-hydroxyapatite (Sr-HA) coated roughened titanium surfaces. Methods: Sr-HA coating and HA coating were fabricated on roughened titanium surfaces by electrochemical deposition technique and characterized by field emission scanning electron microscope (FESM). BMSCs were cultured on Sr-HA coating, HA coating and roughened titanium surfaces respectively. Cell proliferation, alkaline phosphatase (ALP) activity, mineralized nodules formation and cell osteocalcin (OC) secretion were measured. Results: Electrochemically deposited Sr-HA coating and HA coating had no effect on the proliferation of BMSCs and demonstrated that the materials have a good biocompatibility. BMSCs cultured on Sr-HA coating showed increased alkaline phosphatase activity, mineralized nodules formation, and cell OC secretion compared with the other two groups. Cells cultured on HA coating also showed increased biological activity compared with the roughened group. Conclusion: Sr-HA coated titanium surfaces by electrochemical deposition can promote osteogenesis of BMSCs in vitro and have the potential to shorten bone healing period and enhance implant osseointegration. PMID:25784995

  17. Constructing heterostructure on highly roughened caterpillar-like gold nanotubes with cuprous oxide grains for ultrasensitive and stable nonenzymatic glucose sensor.

    PubMed

    Chen, Anran; Ding, Yu; Yang, Zhimao; Yang, Shengchun

    2015-12-15

    In this study, a metal-metal oxide heterostructure was designed and constructed by growing cuprous oxide (Cu2O) grains on highly surface roughened caterpillar-like Au nanotubes (CLGNs) for ultrasensitive, selective and stable nonenzymatic glucose biosensors. The Cu2O grains are tightly anchored to the surface of CLGNs by the spines, resulting in a large increase in the contact area between Cu2O grains and the CLGNs, which facilitates the electron transport between metal and metal oxide and improves the sensitivity and stability of the sensors. The electron transfer coefficient (α) and electron transfer rate constant (ks) for redox reaction of Cu2O-CLGNs/GCE are found to be 0.50114 and 3.24±0.1 s(-1), respectively. The biosensor shows a linear response to glucose over a concentration range of 0.1-5mM and a high sensitivity of 1215.7 µA mM(-1) cm(-2) with a detection limit of 1.83 μM. Furthermore, the Cu2O-CLGNs biosensor exhibited strong anti-interference capability against uric acid (UA), ascorbic acid (AA), potassium chloride (KCl) and sodium ascorbate (SA), as well as a high stability and repeatability. Our current research indicates that the Cu2O-CLGNs hybrid electrode is a promising choice for constructing nonenzyme based electrochemical biosensors. PMID:26258877

  18. Constructing heterostructure on highly roughened caterpillar-like gold nanotubes with cuprous oxide grains for ultrasensitive and stable nonenzymatic glucose sensor.

    PubMed

    Chen, Anran; Ding, Yu; Yang, Zhimao; Yang, Shengchun

    2015-12-15

    In this study, a metal-metal oxide heterostructure was designed and constructed by growing cuprous oxide (Cu2O) grains on highly surface roughened caterpillar-like Au nanotubes (CLGNs) for ultrasensitive, selective and stable nonenzymatic glucose biosensors. The Cu2O grains are tightly anchored to the surface of CLGNs by the spines, resulting in a large increase in the contact area between Cu2O grains and the CLGNs, which facilitates the electron transport between metal and metal oxide and improves the sensitivity and stability of the sensors. The electron transfer coefficient (α) and electron transfer rate constant (ks) for redox reaction of Cu2O-CLGNs/GCE are found to be 0.50114 and 3.24±0.1 s(-1), respectively. The biosensor shows a linear response to glucose over a concentration range of 0.1-5mM and a high sensitivity of 1215.7 µA mM(-1) cm(-2) with a detection limit of 1.83 μM. Furthermore, the Cu2O-CLGNs biosensor exhibited strong anti-interference capability against uric acid (UA), ascorbic acid (AA), potassium chloride (KCl) and sodium ascorbate (SA), as well as a high stability and repeatability. Our current research indicates that the Cu2O-CLGNs hybrid electrode is a promising choice for constructing nonenzyme based electrochemical biosensors.

  19. Design and fabrication of silver-hydrogen cells

    NASA Technical Reports Server (NTRS)

    Klein, M. G.

    1975-01-01

    The design and fabrication of silver-hydrogen secondary cells capable of delivering higher energy densities than comparable nickel-cadmium and nickel-hydrogen cells and relatively high cycle life is presented. An experimental task utilizing single electrode pairs for the optimization of the individual electrode components, the preparation of a design for lightweight 20Ahr cells, and the fabrication of four 20Ahr cells in heavy wall test housing containing electrode stacks of the lightweight design are described. The design approach is based on the use of a single cylindrical self-contained cell with a stacked disc sequence of electrodes. The electrode stack design is based on the use of NASA- Astropower Separator Material, PPF fuel cell anodes, an intercell electrolyte reservoir concept and sintered silver electrodes. Results of performance tests are given.

  20. Convective Heat Transfer from Castings of Ice Roughened Surfaces in Horizontal Flight

    NASA Technical Reports Server (NTRS)

    Dukhan, Nihad; Vanfossen, G. James, Jr.; Masiulaniec, K. Cyril; Dewitt, Kenneth J.

    1995-01-01

    A technique was developed to cast frozen ice shapes that had been grown on a metal surface. This technique was applied to a series of ice shapes that were grown in the NASA Lewis Icing Research Tunnel on flat plates. Eight different types of ice growths, characterizing different types of roughness, were obtained from these plates, from which aluminum castings were made. Test strips taken from these castings were outfitted with heat flux gages, such that when placed in a dry wind tunnel, they could be used to experimentally map out the convective heat transfer coefficient in the direction of flow from the roughened surfaces. The effects on the heat transfer coefficient for parallel flow, which simulates horizontal flight, were studied. The results of this investigation can be used to help size heaters for wings, helicopter rotor blades, jet engine intakes, etc., or de-icing for anti-icing applications where the flow is parallel to the iced surface.

  1. Experimental investigation of impingement heat transfer from a round rib-roughened surface

    NASA Astrophysics Data System (ADS)

    Isman, Mustafa Kemal; Can, Muhiddin

    2016-09-01

    An experimental investigation on impingement heat transfer from a rib-roughened surface is performed. Single, double, and triple rib configurations are tested. The rib is also located at three different positions for a single rib case. The Reynolds number is varied from 10,000 to 50,000 whereas the dimensionless jet-to-surface distance (z/D) is kept constant as 8. Results show that, the Nusselt number decreases just before a rib. After the rib, however, the Nusselt number decreases by a larger amount. Since ribs cause a reincreasing in the Nusselt number after the stagnation point and since the stagnation point Nusselt number is not affected by ribs, they can be used to enhance heat transfer especially for spot cooling applications. It is also obtained that using ribs is more useful for low speed impinging jets, when heat transfer from the whole surface is considered.

  2. Electrochemically Created Highly Surface Roughened Ag Nanoplate Arrays for SERS Biosensing Applications

    PubMed Central

    Slotcavage, Daniel; Mai, John D.; Guo, Feng; Li, Sixing; Zhao, Yanhui; Lei, Yong; Cameron, Craig E.

    2014-01-01

    Highly surface-roughened Ag nanoplate arrays are fabricated using a simple electrodeposition and in situ electrocorrosion method with inorganic borate ions as capping agent. The electrocorrosion process is induced by a change in the local pH value during the electrochemical growth, which is used to intentionally carve the electrodeposited structures. The three dimensionally arranged Ag nanoplates are integrated with substantial surface-enhanced Raman scattering (SERS) hot spots and are free of organic contaminations widely used as shaping agents in previous works, making them excellent candidate substrates for SERS biosensing applications. The SERS enhancement factor of the rough Ag nanoplates is estimated to be > 109. These Ag nanoplate arrays are used for SERS-based analysis of DNA hybridization monitoring, protein detection, and virus differentiation without any additional surface modifications or labelling. They all exhibit an extremely high detection sensitivity, reliability, and reproducibility. PMID:25383191

  3. Roughening and Preroughening of Diamond-Cubic {l_brace}111{r_brace} Surfaces

    SciTech Connect

    Woodraska, D.L.; Jaszczak, J.A.

    1997-01-01

    A solid-on-solid model for {l_brace}111{r_brace} surfaces of diamond-cubic materials that correctly takes into account the diamond-cubic crystal structure has been developed for Monte Carlo simulation. In addition to a roughening transition at temperature T{sub R}, a distinct preroughening transition at T{sub PR}{approx}0.43T{sub R} is indicated by divergences in the surface specific heat and order-parameter susceptibility. Preroughening appears to arise naturally in our nearest-neighbor bond model from the entropic freedom available in the nontrivial crystal structure. Preroughening is shown to dramatically lower the nucleation barrier for growth and etching at low driving forces. {copyright} {ital 1997} {ital The American Physical Society}

  4. Smoothing and re-roughening processes: The geometric evolution of a single fault zone

    NASA Astrophysics Data System (ADS)

    Shervais, Katherine A. H.; Kirkpatrick, James D.

    2016-10-01

    The geometry of a fault zone exerts a major control on earthquake rupture processes and source parameters. Observations previously compiled from multiple faults suggest that fault surface shape evolves with displacement, but the specific processes driving the evolution of fault geometry within a single fault zone are not well understood. Here, we characterize the deformation history and geometry of an extraordinarily well-exposed fault using maps of cross-sectional exposures constructed with the Structure from Motion photogrammetric method. The La Quinta Fault, located in southern California, experienced at least three phases of deformation. Multiple layers of ultracataclasite formed during the most recent phase. Crosscutting relations between the layers define the evolution of the structures and demonstrate that new layers formed successively during the deformation history. Wear processes such as grain plucking from one layer into a younger layer and truncation of asperities at layer edges indicate that the layers were slip zones and the contacts between them slip surfaces. Slip surfaces that were not reactivated or modified after they were abandoned exhibit self-affine geometry, preserving the fault roughness from different stages of faulting. Roughness varies little between surfaces, except the last slip zone to form in the fault, which is the smoothest. This layer contains a distinct mineral assemblage, indicating that the composition of the fault rock exerts a control on roughness. In contrast, the similar roughness of the older slip zones, which have comparable mineralogy but clearly crosscut one another, suggests that as the fault matured the roughness of the active slip surface stayed approximately constant. Wear processes affected these layers, so for roughness to stay constant the roughening and smoothing effects of fault slip must have been approximately balanced. These observations suggest fault surface evolution occurs by nucleation of new surfaces and

  5. Controlled atmosphere for fabrication of cermet electrodes

    DOEpatents

    Ray, Siba P.; Woods, Robert W.

    1998-01-01

    A process for making an inert electrode composite wherein a metal oxide and a metal are reacted in a gaseous atmosphere at an elevated temperature of at least about 750.degree. C. The metal oxide is at least one of the nickel, iron, tin, zinc and zirconium oxides and the metal is copper, silver, a mixture of copper and silver or a copper-silver alloy. The gaseous atmosphere has an oxygen content that is controlled at about 5-3000 ppm in order to obtain a desired composition in the resulting composite.

  6. Controlled atmosphere for fabrication of cermet electrodes

    DOEpatents

    Ray, S.P.; Woods, R.W.

    1998-08-11

    A process is disclosed for making an inert electrode composite wherein a metal oxide and a metal are reacted in a gaseous atmosphere at an elevated temperature of at least about 750 C. The metal oxide is at least one of the nickel, iron, tin, zinc and zirconium oxides and the metal is copper, silver, a mixture of copper and silver or a copper-silver alloy. The gaseous atmosphere has an oxygen content that is controlled at about 5--3000 ppm in order to obtain a desired composition in the resulting composite. 2 figs.

  7. The fate of nano-silver in aqueous media.

    PubMed

    Plowman, Blake J; Tschulik, Kristina; Walport, Emily; Young, Neil P; Compton, Richard G

    2015-08-01

    Silver nanoparticles offer highly attractive properties for many applications, however concern has been raised over the possible toxicity of this material in environmental systems. While it is thought that the release of Ag(+) can play a crucial role in this toxicity, the mechanism by which the oxidative dissolution of nano-silver occurs is not yet understood. Here we address this through the electrochemical analysis of gold-core silver-shell nanoparticles in various solutions. This novel method allows the direct quantification of silver dissolution by normalisation to the gold core signal. This is shown to be highly effective at discriminating between silver dissolution and the loss of nanoparticles from the electrode surface. We evidence through this rigorous approach that the reduction of O2 drives the dissolution of nano-silver, while in the presence of Cl(-) this dissolution is greatly inhibited. This work is extended to the single nanoparticle level using nano-impact experiments. PMID:26151641

  8. Silver nanoparticles-coated glass frits for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Li, Yingfen; Gan, Weiping; Li, Biyuan

    2016-04-01

    Silver nanoparticles-coated glass frit composite powders for silicon solar cells were prepared by electroless plating. Silver colloids were used as the activating agent of glass frits. The products were characterized by X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. The characterization results indicated that silver nanoparticles with the melting temperature of 838 °C were uniformly deposited on glass frit surface. The particle size of silver nanoparticles could be controlled by adjusting the [Ag(NH3)2]NO3 concentration. The as-prepared composite powders were applied in the front side metallization of silicon solar cells. Compared with those based on pure glass frits, the solar cells containing the composite powders had the denser silver electrodes and the better silver-silicon ohmic contacts. Furthermore, the photovoltaic performances of solar cells were improved after the electroless plating.

  9. Electrode compositions

    DOEpatents

    Block, Jacob; Fan, Xiyun

    1998-01-01

    An electrode composition for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C.sub.8 -C.sub.15 alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5-4.5 volts.

  10. Electrode compositions

    DOEpatents

    Block, J.; Fan, X.

    1998-10-27

    An electrode composition is described for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C{sub 8}-C{sub 15} alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5--4.5 volts.

  11. Photoelectrolytic production of hydrogen using semiconductor electrodes

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.; Walker, G. H.

    1976-01-01

    Experimental data for the photoelectrolytic production of hydrogen using GaAs photoanodes was presented. Four types of GaAs anodes were investigated: polished GaAs, GaAs coated with gold, GaAs coated with silver, and GaAs coated with tin. The maximum measured efficiency using a tungsten light source was 8.9 percent for polished GaAs electrodes and 6.3 percent for tin coated GaAs electrodes.

  12. Magnetohydrodynamic electrode

    DOEpatents

    Boquist, Carl W.; Marchant, David D.

    1978-01-01

    A ceramic-metal composite suitable for use in a high-temperature environment consists of a refractory ceramic matrix containing 10 to 50 volume percent of a continuous high-temperature metal reinforcement. In a specific application of the composite, as an electrode in a magnetohydrodynamic generator, the one surface of the electrode which contacts the MHD fluid may have a layer of varying thickness of nonreinforced refractory ceramic for electrode temperature control. The side walls of the electrode may be coated with a refractory ceramic insulator. Also described is an electrode-insulator system for a MHD channel.

  13. Heat transfer and fluid flow analysis of artificially roughened ducts having rib and groove roughness

    NASA Astrophysics Data System (ADS)

    Aharwal, K. R.; Pawar, C. B.; Chaube, Alok

    2014-06-01

    Artificially roughness is one of the well known methods of enhancing heat transfer from the heat transfer surface in the form of repeated ribs, grooves or combination of ribs and groove (compound turbulators). The artificial roughness produced on the heat transferring surface is used in cooling of gas turbine blades, nuclear reactor, solar air heating systems etc. Solar air heaters have wide applications in low to moderate temperature range, namely, drying of foods, agricultural crops, seasoning of wood and space heating etc. Solar air heaters have low value of convective heat transfer coefficient between the working fluid (air) and the heat transferring surface, due to the formation of thin laminar viscous sub-layer on its surface. The heat transfer from the surface can be increased by breaking this laminar viscous sub layer. Hence, in the present work compound turbulators in the form of integral wedge shaped ribs with grooves are used on the heat transfer surface, to study its effect on the heat transfer coefficient (Nusselt number) and friction factor in the range of Reynolds number 3,000-18,000. The roughness produced on the absorber plate forms the wetted side of upper broad wall of the rectangular duct of solar air heater. The relative groove position ( g/p) was varied from 0.4 to 0.8 and the wedge angle (Φ) was varied from 10° to 25°, relative roughness pitch ( p/e) and relative roughness height ( e/D) was maintained as 8.0 and 0.033 respectively. The aspect ratio of the rectangular duct was maintained as 8. The Nusselt number and friction factor of the artificially roughened ducts were determined experimentally and the corresponding values were compared with that of smooth surface duct. It is observed that wedge-groove roughened surface shows more enhancement in heat transfer compared to only rib roughened surface arrangement. The investigation revealed that Nusselt number increases 1.5-3 times, while the friction factor increases two to three folds that

  14. Working Electrodes

    NASA Astrophysics Data System (ADS)

    Komorsky-Lovrić, Šebojka

    In electrochemistry an electrode is an electronic conductor in contact with an ionic conductor. The electronic conductor can be a metal, or a semiconductor, or a mixed electronic and ionic conductor. The ionic conductor is usually an electrolyte solution; however, solid electrolytes and ionic melts can be used as well. The term "electrode" is also used in a technical sense, meaning the electronic conductor only. If not specified otherwise, this meaning of the term "electrode" is the subject of the present chapter. In the simplest case the electrode is a metallic conductor immersed in an electrolyte solution. At the surface of the electrode, dissolved electroactive ions change their charges by exchanging one or more electrons with the conductor. In this electrochemical reaction both the reduced and oxidized ions remain in solution, while the conductor is chemically inert and serves only as a source and sink of electrons. The technical term "electrode" usually also includes all mechanical parts supporting the conductor (e.g., a rotating disk electrode or a static mercury drop electrode). Furthermore, it includes all chemical and physical modifications of the conductor, or its surface (e.g., a mercury film electrode, an enzyme electrode, and a carbon paste electrode). However, this term does not cover the electrolyte solution and the ionic part of a double layer at the electrode/solution interface. Ion-selective electrodes, which are used in potentiometry, will not be considered in this chapter. Theoretical and practical aspects of electrodes are covered in various books and reviews [1-9].

  15. Substrate effects and diffusion dominated roughening in Cu2O electrodeposition

    NASA Astrophysics Data System (ADS)

    Brandt, I. S.; Zoldan, V. C.; Stenger, V.; Plá Cid, C. C.; Pasa, A. A.; Oliveira, T. J.; Aarão Reis, F. D. A.

    2015-10-01

    Cuprous oxide (Cu2O) films from 25 nm to 1500 nm were electrodeposited on n-Si(100) and Ni/n-Si(100) substrates from aqueous solution at room temperature. X-ray diffraction and transmission electron microscopy imaging show that the Cu2O structure and morphology are strongly affected by the substrate choice, with V shape and U shape columnar growth on n-Si(100) and Ni/n-Si(100), respectively. Atomic force microscopy reveals the presence of rounded grains at the surface in both cases. Anomalous and normal roughening are observed in films grown on n-Si and Ni, respectively, but estimates of scaling exponents are not conclusive. On the other hand, the distributions of local heights, roughness, and extremal heights show good agreement with those of the fourth order linear stochastic equation of Mullins and Herring (MH). Thus, surface dynamics in both systems is dominated by diffusion of adsorbed molecules, with no large scale effect of possible inhomogeneities in mass flux from the solution or in reaction and adsorption rates. In growth on n-Si substrates, the noise amplitude of the MH equation increases in time as t0.8 , while the coefficient of the curvature-related term is time-independent. Step edge energy barriers restrict the mass flux across grain boundaries, thus a broad size distribution of initial grains leads to coarsening of the larger ones. This explains their V shape in the thickest films and establishes a connection with the anomalous roughening. These effects are reduced in films grown on Ni/n-Si, which initially have much larger grains with narrower size distributions and, consequently, smaller fluctuations in coarse grained growth rates. Thus, despite the relevance of electrochemical conditions for Cu2O films to grow and their influence on crystallographic orientation, large scale surface features are determined by physical properties of the material and its interactions with the substrate, with a universal microscopic dynamics similar to vapor

  16. Surface enhanced Raman scattering of melamine on silver substrate: An experimental and DFT study.

    PubMed

    An, Nguyen Thi Thai; Dao, Duy Quang; Nam, Pham Cam; Huy, Bui The; Nhung Tran, Hong

    2016-12-01

    Surface enhanced Raman spectroscopy (SERS) is a powerful vibrational spectroscopy technique that allows amplifying weak Raman signals by the excitation of localized surface plasmons. In this paper, we used nanoscale roughened silver surface to enhance Raman signals of melamine analyte. Silver nanoparticles were synthesized by wet-chemical method and employed for SERS measurement. Theoretically, optimized geometries and vibrational frequencies of melamine and melamine absorbed on silver-cluster surface were calculated by using the B3LYP/6-31G(d) method. Then, the predicted spectrograms are compared with the experimental Raman spectra. As a result, Raman signals of melamine were dramatically enhanced by using obtained silver nanoparticles as the substrate. Typical peaks of melamine at 676 and 983cm(-1) were enhanced and could be obviously observed in experiments. The calculated vibrational frequencies seem to relatively coincide with the experimental values. SERS effect of melamine on nanoscale silver was also explained by analyzing molecular frontier orbitals (HOMO and LUMO) melamine-silver complexes.

  17. Partitioning of silver and chemical speciation of free Ag in soils amended with nanoparticles

    PubMed Central

    2013-01-01

    Background Knowledge about silver nanoparticles in soils is limited even if soils are a critical pathway for their environmental fate. In this paper, speciation results have been acquired using a silver ion selective electrode in three different soils. Results Soil organic matter and pH were the most important soil properties controlling the occurrence of silver ions in soils. In acidic soils, more free silver ions are available while in the presence of organic matter, ions were tightly bound in complexes. The evolution of the chemical speciation of the silver nanoparticles in soils was followed over six months. Conclusion During the first few hours, there appeared to be a strong sorption of the silver with soil ligands, whereas over time, silver ions were released, the final concentration being approximately 10 times higher than at the beginning. Ag release was associated with either the oxidation of the nanoparticles or a dissociation of adsorbed silver from the soil surfaces. PMID:23617903

  18. The effect of liquid configuration in porous gas electrodes.

    NASA Technical Reports Server (NTRS)

    Katan, T.; Grens, E. A., II

    1971-01-01

    Measurement of the influence of differential pressure on electrode activity in oxygen cathodes made up of beds of uniform silver spheres (156 micron diameter). The extent and nature of this dependence could be explained through use of the concept of pendular and funicular liquid configuration in the pore space of the electrode.

  19. Fabrication of an Inexpensive Ion-Selective Electrode.

    ERIC Educational Resources Information Center

    Palanivel, A.; Riyazuddin, P.

    1984-01-01

    The preparation and performance of a graphite (silver/copper sulfide) electrode is described. This rod, extracted from a used dry cell, is an acceptable substitute for ion-selective electrodes after it has been cleaned by abrasion followed by an overnight treatment with hydrochloric acid. (JN)

  20. Surface roughening during plasma-enhanced chemical-vapor deposition of hydrogenated amorphous silicon on crystal silicon substrates

    NASA Astrophysics Data System (ADS)

    Tanenbaum, D. M.; Laracuente, A. L.; Gallagher, Alan

    1997-08-01

    The morphology of a series of thin films of hydrogenated amorphous silicon (a-Si:H) grown by plasma-enhanced chemical-vapor deposition (PECVD) is studied using scanning tunneling microscopy. The substrates were atomically flat, oxide-free, single-crystal silicon. Films were grown in a PECVD chamber directly connected to a surface analysis chamber with no air exposure between growth and measurement. The homogeneous roughness of the films increases with film thickness. The quantification of this roughening is achieved by calculation of both rms roughness and lateral correlation lengths of the a-Si:H film surface from the height difference correlation functions of the measured topographs. Homogeneous roughening occurs over the film surface due to the collective behavior of the flux of depositing radical species and their interactions with the growth surface.

  1. Surface roughening during plasma-enhanced chemical-vapor deposition of hydrogenated amorphous silicon on crystal silicon substrates

    SciTech Connect

    Tanenbaum, D.M.; Laracuente, A.L.; Gallagher, A.

    1997-08-01

    The morphology of a series of thin films of hydrogenated amorphous silicon (a-Si:H) grown by plasma-enhanced chemical-vapor deposition (PECVD) is studied using scanning tunneling microscopy. The substrates were atomically flat, oxide-free, single-crystal silicon. Films were grown in a PECVD chamber directly connected to a surface analysis chamber with no air exposure between growth and measurement. The homogeneous roughness of the films increases with film thickness. The quantification of this roughening is achieved by calculation of both rms roughness and lateral correlation lengths of the a-Si:H film surface from the height difference correlation functions of the measured topographs. Homogeneous roughening occurs over the film surface due to the collective behavior of the flux of depositing radical species and their interactions with the growth surface. {copyright} {ital 1997} {ital The American Physical Society}

  2. Production of silver ions from colloidal silver by nanoparticle iontophoresis system.

    PubMed

    Tseng, Kuo-Hsiung; Liao, Chih-Yu

    2011-03-01

    Metal ions, especially the silver ion, were used to treat infection before the initiation of antibiotic therapy. Unfortunately, there is a lack of research on the metallic nanoparticle suspension as a reservoir for metal ion release application. For medical purposes, conversion of colloidal silver into an ionic form is necessary, but not using silver salts (e.g., AgNO3, Ag2SO4), due to the fact that the counter-ion of silver salts may cause problems to the body as the silver ion (Ag+) is consumed. The goal of this research is to develop a silver nanoparticle iontophoresis system (NIS) which can provide a relatively safe bactericidal silver ion solution with a controllable electric field. In this study, ion-selective electrodes were used to identify and observe details of the system's activity. Both qualitative and quantitative data analyses were performed. The experimental results show that the ion releasing peak time (R(PT)) has an inversely proportional relationship with the applied current and voltage. The ion releasing maximum level (R(ML)) and dosage (R(D)) are proportional to the current density and inversely proportional to the voltage, respectively. These results reveal that the nanoparticle iontophoresis system (NIS) is an alternative method for the controlled release of a metal ion and the ion's concentration profile, by controlling the magnitude of current density (1 microA/cm2 equal to 1 ppm/hour) and applied voltage.

  3. The truth about silver.

    PubMed

    Ovington, Liza G

    2004-09-01

    Interest in silver as a topical agent in wound healing is undergoing a renaissance. Having basic information regarding silver's chemical properties and potential actions in the wound bed is important to its appropriate clinical use. Such information is also relevant to the interpretation of silver's in vitro antimicrobial (antiseptic) effects, which in turn relate to issues involved in the evaluation of the clinical effects of silver in vivo. Gaining an understanding of the basic science of silver products and the different challenges inherent to in vitro versus in vivo antimicrobial evaluations will allow clinicians to address several key questions inherent when considering the use of silver as a topical antimicrobial: 1) Are there different forms of silver? 2) How does the amount of silver released into the wound environment correlate with clinical benefit? 3) How does the rate of silver release correlate with clinical benefit?

  4. Proper Orthogonal Decomposition Analysis of Turbulent Jet Impingement on Rib-roughened Surface

    NASA Astrophysics Data System (ADS)

    Lam, Prasanth Anand Kumar; Karaiyan, Arul Prakash; Thermo-Fluid Dynamics Laboratory Team

    2015-11-01

    A Proper Orthogonal Decomposition (POD) analysis on turbulent flow dynamics of confined slot jet impinging on rib-roughened surface is numerically investigated. The data for POD analysis has been obtained by solving mass, momentum and energy equations in Cartesian framework using Streamline Upwind/Petrov-Galerkin Finite element method. Further, turbulent kinetic energy (k) and its dissipation rate (ɛ) are modeled using standard k- ɛ turbulence model with standard wall functions. POD is applied to computational data for a wide range of Reynolds number (Re) = 5000 - 30000 and non-dimensional channel height (H/L) = 0.5 - 4.0 to reveal large scale vortical structures in the flow field. The simulated results demonstrate a better understanding on effect of turbulence and its influence on individual vortical structures for enhancement of heat transfer. The enhancement of heat transfer in stagnation region due to combined effect of oscillation in impingement position caused by large vortical structures and strong acceleration of fluid during impingement is quantified. Furthermore, non-dimensional correlations have been derived for pressure drop and Surface averaged Nusselt number.

  5. Role of substrate in the surface diffusion and kinetic roughening of nanocrystallised nickel electrodeposits

    NASA Astrophysics Data System (ADS)

    Nzoghe-Mendome, L.; Aloufy, A.; Ebothé, J.; El Messiry, M.; Hui, D.

    2009-02-01

    The surface growth and roughening of nano-crystallised Ni electrodeposits prepared at the same conditions have been studied on Cu, Au and ITO substrates. The Ni films obtained are characterised by the same face-centred cubic structure with a texture affected by the substrate chemical nature. Practically, the same small-sized grains of 83 nm mean height depicting a statistical mono-mode feature grow on Cu. A three-modal feature corresponding to the biggest and compact crystallites of 335, 368 and 400 nm mean height is obtained with Au. Two typical modes, respectively, linked to isolated big crystallites of 343 nm mean height and large zones of small grains of 170 nm height, result from the ITO effect. The surface transport properties of Ni ad-atoms on each substrate have been studied from the theoretical approach including the film global roughness measured by AFM. It is shown that the ad-atom diffusion coefficients ( D s) ranged in the interval 10 -10-10 -9 cm 2 s -1 are greatly affected by the non-equilibrium conditions of the film formation. Cu and ITO, respectively, lead to Λ s=11.92 and 14.30 nm, while the higher D s value and diffusion length Λ s=37.32 nm are obtained with Au substrate.

  6. Numerical sensitivity analysis of 3- and 2- dimensional rib-roughened channels

    NASA Astrophysics Data System (ADS)

    Keshmiri, Amir

    2012-07-01

    Rough surfaces have been used as a tool to enhance heat transfer by increasing the level of turbulence mixing in the flow. In numerically simulating such flows, it is common to simulate a 3D rib-roughened channel with a 2D domain in order to reduce the computational time and power. The main purpose of the present work is to investigate the accuracy of the above approximation. In order to do so, initially a 3D channel is simulated using Reynolds-Averaged Navier-Stokes technique and comparison is made against 2D simulations as well as experimental data. In addition, the effects of rib thermal boundary condition and near-wall treatments are also investigated. All computations are undertaken using the commercial CFD code `STAR-CD'. The Reynolds number, based on the channel bulk velocity and hydraulic diameter, is 30,000. Two low-Reynolds-number linear Eddy-Viscosity Models, namely the Lien-Chen-Leschziner k - ɛ model and a variant of Durbin's v 2 - f formulation are used. In the CFD simulations reported here, the focus is on the experimental data of Rau et al. (ASME J Turbomach 120:368-375, 1998). It was found that the present results for a 3D channel are in relatively good agreement with the data. It was also shown that a 2D channel can be used to represent the flow in the centre-line of a 3D channel with relatively good accuracy.

  7. Entanglement in correlated random spin chains, RNA folding and kinetic roughening

    NASA Astrophysics Data System (ADS)

    Rodríguez-Laguna, Javier; Santalla, Silvia N.; Ramírez, Giovanni; Sierra, Germán

    2016-07-01

    Average block entanglement in the 1D XX-model with uncorrelated random couplings is known to grow as the logarithm of the block size, in similarity to conformal systems. In this work we study random spin chains whose couplings present long range correlations, generated as gaussian fields with a power-law spectral function. Ground states are always planar valence bond states, and their statistical ensembles are characterized in terms of their block entropy and their bond-length distribution, which follow power-laws. We conjecture the existence of a critical value for the spectral exponent, below which the system behavior is identical to the case of uncorrelated couplings. Above that critical value, the entanglement entropy violates the area law and grows as a power law of the block size, with an exponent which increases from zero to one. Interestingly, we show that XXZ models with positive anisotropy present the opposite behavior, and strong correlations in the couplings lead to lower entropies. Similar planar bond structures are also found in statistical models of RNA folding and kinetic roughening, and we trace an analogy between them and quantum valence bond states. Using an inverse renormalization procedure we determine the optimal spin-chain couplings which give rise to a given planar bond structure, and study the statistical properties of the couplings whose bond structures mimic those found in RNA folding.

  8. Computational prediction of heat transfer to gas turbine nozzle guide vanes with roughened surfaces

    SciTech Connect

    Guo, S.M.; Jones, T.V.; Lock, G.D.; Dancer, S.N.

    1998-04-01

    The local Mach number and heat transfer coefficient over the aerofoil surfaces and endwalls of a transonic gas turbine nozzle guide vane have been calculated. the computations were performed by solving the time-averaged Navier-Stokes equations using a fully three-dimensional computational code (CFDS), which is well established at Rolls-Royce. A model to predict the effects of roughness has been incorporated into CFDS and heat transfer levels have been calculated for both hydraulically smooth and transitionally rough surfaces. The roughness influences the calculations in two ways; first the mixing length at a certain height above the surface is increased; second the wall function used to reconcile the wall condition with the first grid point above the wall is also altered. The first involves a relatively straightforward shift of the origin in the van Driest damping function description, the second requires an integration of the momentum equation across the wall layer. A similar treatment applies to the energy equation. The calculations are compared with experimental contours of heat transfer coefficient obtained using both thin-film gages and the transient liquid crystal technique. Measurements were performed using both hydraulically smooth and roughened surfaces, and at engine-representative Mach and Reynolds numbers. The heat transfer results are discussed and interpreted in terms of surface-shear flow visualization using oil and dye techniques.

  9. Composites reinforced via mechanical interlocking of surface-roughened microplatelets within ductile and brittle matrices.

    PubMed

    Libanori, R; Carnelli, D; Rothfuchs, N; Binelli, M R; Zanini, M; Nicoleau, L; Feichtenschlager, B; Albrecht, G; Studart, A R

    2016-06-01

    Load-bearing reinforcing elements in a continuous matrix allow for improved mechanical properties and can reduce the weight of structural composites. As the mechanical performance of composite systems are heavily affected by the interfacial properties, tailoring the interactions between matrices and reinforcing elements is a crucial problem. Recently, several studies using bio-inspired model systems suggested that interfacial mechanical interlocking is an efficient mechanism for energy dissipation in platelet-reinforced composites. While cheap and effective solutions are available at the macroscale, the modification of surface topography in micron-sized reinforcing elements still represents a challenging task. Here, we report a simple method to create nanoasperities with tailored sizes and densities on the surface of alumina platelets and investigate their micromechanical effect on the energy dissipation mechanisms of nacre-like materials. Composites reinforced with roughened platelets exhibit improved mechanical properties for both organic ductile epoxy and inorganic brittle cement matrices. Mechanical interlocking increases the modulus of toughness (area under the stress-strain curve) by 110% and 56% in epoxy and cement matrices, respectively, as compared to those reinforced with flat platelets. This interlocking mechanism can potentially lead to a significant reduction in the weight of mechanical components while retaining the structural performance required in the application field. PMID:27070938

  10. Fabrication of Dry Electrode for Recording Bio-potentials

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Guo, Kai; Pei, Wei-Hua; Gui, Qiang; Li, Xiao-Qian; Chen, Hong-Da; Yang, Jian-Hong

    2011-01-01

    Development of minimally invasive dry electrodes for recording biopotentials is presented. The detailed fabrication process is outlined. A dry electrode is formed by a number of microneedles. The lengths of the microneedles are about 150μm and the diameters are about 50μm. The tips of the microneedles are sharp enough to penetrate into the skin. The silver/silver chloride is grown on microneedle arrays and demonstrates good character. The electrocardiogram shows that the dry electrode is suitable for recording biopotentials.

  11. Liquid electrode

    DOEpatents

    Ekechukwu, Amy A.

    1994-01-01

    A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

  12. Transparent nanowire network electrode for textured semiconductors.

    PubMed

    Gao, Jinwei; Pei, Ke; Sun, Tianyi; Wang, Yaohui; Zhang, Linghai; Peng, Weijin; Lin, Qinggeng; Giersig, Michael; Kempa, Krzysztof; Ren, Zhifeng; Wang, Yang

    2013-03-11

    This work presents an inexpensive and easily manufacturable, highly conductive and transparent nanowire network electrode for textured semiconductors. It is based on lines of silver nanoparticles transformed into a nanowire network by microwave or furnace sintering. The nanonetwork electrode on crystalline silicon is demonstrated experimentally, with the nanoparticles self-assembling in the valleys between the pyramids of the textured surface. Optical experiments show that this conductive nanowire network electrode can be essentially 'invisible' when covered with the conventional anti-reflection coating (ARC), and thus could be employed in photovoltaic applications.

  13. An electrochemical amplification immunoassay using bi-electrode signal transduction system.

    PubMed

    Chen, Zhao-Peng; Jiang, Jian-Hui; Zhang, Xiao-Bing; Shen, Guo-Li; Yu, Ru-Qin

    2007-03-30

    An electrochemical immunoassay technique has been developed based on the sensitive detection of the enzyme-generated product with a bi-electrode signal transduction system. The system uses two separate electrodes, an immunoelectrode and a detection electrode to form a galvanic cell to implement the redox reactions on two different electrodes, that is the enzyme-generated reductant in the anode region is electrochemically oxidized by an oxidant (silver ions) in the cathode apartment. Based on a sandwich procedure, after immunoelectrode with antibody immobilized on its surface bound with the corresponding antigen and alkaline phosphatase conjugated antibody successively, the immunoelectrode was placed in enzyme reaction solution and wired to the detection electrode which was immerged into a silver deposition solution. These two solutions are connected with a salt bridge. Thus a bi-electrode signal transduction system device is constructed in which the immunoelectrode acts as anode and the detection electrode serves as cathode. The enzyme bound on the anode surface initiates the hydrolysis of ascorbic acid 2-phosphate to produce ascorbic acid in the anode region. The ascorbic acid produced in the anodic apartment is electrochemically oxidized by silver ions coupled with the deposition of silver metal on the cathode. Via a period of 30min deposition, silver will deposited on the detection electrode in an amount corresponding to the quantity of ascorbic acid produced, leading to a great enhancement in the electrochemical stripping signal due to the accumulation of metallic silver by enzyme-generated product. Compared with the method using chemical deposition of silver, the electrochemical deposition of silver on a separate detection electrode apartment avoids the possible influence of silver deposition on the enzyme activity.

  14. Assembling silver nanowires using optoelectronic tweezers

    NASA Astrophysics Data System (ADS)

    Zhang, Shuailong; Cooper, Jonathan M.; Neale, Steve L.

    2016-03-01

    Light patterned dielectrophoresis or optoelectronic tweezers (OET) has been proved to be an effective micromanipulation technology for cell separation, cell sorting and control of cell interactions. Apart from being useful for cell biology experiments, the capability of moving small objects accurately also makes OET an attractive technology for other micromanipulation applications. In particular, OET has the potential to be used for efficiently and accurately assembling small optoelectronic/electronic components into circuits. This approach could produce a step change in the size of the smallest components that are routinely assembled; down from the current smallest standard component size of 400×200 μm (0402 metric) to components a few microns across and even nanostructured components. In this work, we have demonstrated the use of OET to manipulate conductive silver nanowires into different patterns. The silver nanowires (typical diameter: 60 nm; typical length: 10 μm) were suspended in a 15 mS/m solution of KCL in water and manipulated by positive dielectrophoresis force generated by OET. A proof-of-concept demonstration was also made to prove the feasibility of using OET to manipulate silver nanowires to form a 150-μm-long conductive path between two isolated electrodes. It can be seen that the resistance between two electrodes was effectively brought down to around 700 Ω after the silver nanowires were assembled and the solution evaporated. Future work in this area will focus on increasing the conductivity of these tracks, encapsulating the assembled silver nanowires to prevent silver oxidation and provide mechanical protection, which can be achieved via 3D printing and inkjet printing technology.

  15. Effects of Pin Detached Space on Heat Transfer in a Rib Roughened Channel

    SciTech Connect

    Siw, Sin Chien; Chyu, Minking K.; Alvin, Mary Anne

    2012-11-08

    An experimental study is performed to investigate the heat transfer characteristics and frictional losses in a rib roughened channel combined with detached pin-fins. The overall channel geometry (W=76.2 mm, E=25.4 mm) simulates an internal cooling passage of wide aspect ratio (3:1) in a gas turbine airfoil. With a given pin diameter, D=6.35 mm=[1/4]E, three different pin-fin height-to-diameter ratios, H/D=4, 3, and 2, were examined. Each of these three cases corresponds to a specific pin array geometry of detachment spacing (C) between the pin-tip and one of the endwalls, i.e., C/O=0, 1, 2, respectively. The rib height-to-channel height ratio is 0.0625. Two newly proposed cross ribs, namely the broken rib and full rib are evaluated in this effort. The broken ribs are positioned in between two consecutive rows of pin-fins, while the full ribs are fully extended adjacent to the pin-fins. The Reynolds number, based on the hydraulic diameter of the unobstructed cross section and the mean bulk velocity, ranges from 10,000 to 25,000. The experiment employs a hybrid technique based on transient liquid crystal imaging to obtain distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all pin elements. The presence of ribs enhances local heat transfer coefficient on the endwall substantially by approximately 20% to 50% as compared to the neighboring endwall. In addition, affected by the rib geometry, which is a relatively low profile as compared to the overall height of the channel, the pressure loss seems to be insensitive to the presence of the ribs. However, from the overall heat transfer enhancement standpoint, the baseline cases (without ribs) outperform cases with broken ribs or full ribs.

  16. Interfacial roughening, segregation and dynamic behaviour in a generalized Schelling model

    NASA Astrophysics Data System (ADS)

    Albano, Ezequiel V.

    2012-03-01

    The Schelling model is widely used for the study of segregation behaviour in sociodynamics, econophysics, and related disciplines. Agents of two types placed in a lattice or network are allowed to exchange their locations on the basis of a transfer rule (T(S, A)), which depends on the satisfaction that the agent already has in her/his present position (S), and the attractiveness of the future position (A). The satisfaction and the attractiveness that the agent feels are measured in terms of the fraction between the number of agents of the same type that are present in the neighbourhood of the agent under consideration and the total number of neighbours. In this work we propose a generalization of the Schelling model such that the relative influence of satisfaction and attractiveness can be enhanced or depleted by means of an exponent q, i.e. T(S, A) = (1 - S)qA. We report extensive Monte Carlo numerical simulations performed for the two-dimensional square lattice with initial conditions of two different types: (i) fully disordered configurations of randomly located agents; and (ii) fully segregated configurations with a flat interface between two domains of unlike agents. We show that the proposed model exhibits a rich and interesting complex behaviour that emerges from the competitive interplay between interfacial roughening and the diffusion of isolated agents in the bulk of clusters of unlike agents. The first process dominates the early time regime, while the second one prevails for longer times after a suitable crossover time. Our numerical results are rationalized in terms of a dynamic finite-size scaling ansatz.

  17. Advancements in electrode design and laser techniques for fabricating micro-electrode arrays as part of a retinal prosthesis.

    PubMed

    Dodds, C W D; Schuettler, M; Guenther, T; Lovell, N H; Suaning, G J

    2011-01-01

    Retinal micro-electrode arrays (MEAs) for a visual prosthesis were fabricated by laser structuring of platinum (Pt) foil and liquid silicone rubber. A new design was created using a folding technique to create a multi-layered array from a single Pt sheet. This method allowed a reduction in both the electrode pitch, and the overall width of the array, while maintaining coplanar connection points for more stable interconnections to other components of the system. The design also included a section which could be rolled to create a cylindrical segment in order to minimise the size of the exit in the sclera after implantation. A picosecond mode-locked 532 nm laser system was investigated as a replacement for the nanosecond Q-switched 1064 nm laser currently in use. Trials showed that the ps system could produce high quality electrode tracks with a minimum pitch of 30 μm, less than 40% the pitch achievable with the ns laser. A method was investigated for the cutting of Pt foils without damaging the underlying silicone by laser machining to a depth just below the thickness of the foil. Initial samples showed promise with full penetration of the foil only occurring at cross points of the laser paths. The ps laser was also used to create roughened surfaces, in order to increase the electrochemical surface area of the electrodes. Surfaces were imaged using a scanning electron microscope, and compared to surfaces roughened with the ns laser. The ps laser was seen to offer a reduction in feature size, as well as an increase in control over the appearance of the electrode surface. PMID:22254389

  18. 2D-patterning of self-assembled silver nanoisland films.

    PubMed

    Chervinskii, Semen; Reduto, Igor; Kamenskii, Alexander; Mukhin, Ivan S; Lipovskii, Andrey A

    2016-01-01

    The paper is dedicated to the recently developed by the authors technique of silver nanoisland growth, allowing self-arrangement of 2D-patterns of nanoislands. The technique employs silver out-diffusion from ion-exchanged glass in the course of annealing in hydrogen. To modify the silver ion distribution in the exchanged soda-lime glass we included the thermal poling of the ion-exchanged glass with a profiled electrode as an intermediate stage of the process. The resulting consequence consists of three steps: (i) during the ion exchange of the glass in the AgxNa1-xNO3 (x = 0.01-0.15) melt we enrich the subsurface layer of the glass with silver ions; (ii) under the thermal poling, the electric field displaces these ions deeper into the glass under the 2D profiled anodic electrode, the displacement is smaller under the hollows in the electrode where the intensity of the field is minimal; (iii) annealing in a reducing atmosphere of hydrogen results in silver out-diffusion only in the regions corresponding to the electrode hollows, as a result silver forms nanoislands following the shape of the electrode. Varying the electrode and mode of processing allows governing the nanoisland size distribution and self-arrangement of the isolated single nanoislands, pairs, triples or groups of several nanoislands-so-called plasmonic molecules. PMID:26765367

  19. Liquid electrode

    DOEpatents

    Ekechukwu, A.A.

    1994-07-05

    A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

  20. Electrical properties of metallic electrodes.

    PubMed

    Ragheb, T; Geddes, L A

    1990-03-01

    The series equivalent resistance R and capacitance C of metal/saline electrode/electrolyte interfaces were measured as a function of frequency (100 Hz-20k Hz) and current density (0.25 to 1000 A m-2) for eight typical electrode metals. For each of the metals tested, R decreased and C increased as the current density was increased above a critical value (with the exception of silver and MP35N at frequencies above 1 kHz for which R increased and C decreased slightly). With the exception of copper, the current density linearity limit (for 10 per cent decrease in R or 10 per cent increase in C) increased with increasing frequency and, in most cases, the current density linearity limit for 10 per cent increase in C was slightly less than that for 10 per cent decrease in R. Among the metals tested, copper and aluminium had the lowest current carrying capability and rhodium had the highest current-carrying capability. The current carrying capabilities of 316 SS, platinum, silver and MP35N, were intermediate and similar. With increasing current density, an increase in the electrode/electrolyte capacitance was the most sensitive indicator of the current-carrying linearity limit. PMID:2376994

  1. Optimization of silver-dielectric-silver nanoshell for sensing applications

    SciTech Connect

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-15

    In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

  2. Optimization of silver-dielectric-silver nanoshell for sensing applications

    NASA Astrophysics Data System (ADS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-08-01

    In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell.

  3. Bendable Electro-chemical Lactate Sensor Printed with Silver Nano-particles.

    PubMed

    Abrar, Md Abu; Dong, Yue; Lee, Paul Kyuheon; Kim, Woo Soo

    2016-01-01

    Here we report a flexible amperometric lactate biosensor using silver nanoparticle based conductive electrode. Mechanically bendable cross-serpentine-shaped silver electrode is generated on flexible substrate for the mechanical durability such as bending. The biosensor is designed and fabricated by modifying silver electrode with lactate oxidase immobilized by bovine serum albumin. The in-sensor pseudo Ag/AgCl reference electrode is fabricated by chloridization of silver electrode, which evinced its long-term potential stability against a standard commercial Ag/AgCl reference electrode. The amperometric response of the sensor shows linear dependence with lactate concentration of 1~25 mM/L. Anionic selectivity is achieved by using drop-casted Nafion coated on silver electrode against anionic interferences such as ascorbate. This non-invasive electrochemical lactate sensor also demonstrates excellent resiliency against mechanical deformation and temperature fluctuation which leads the possibility of using it on human epidermis for continuous measurement of lactate from sweat. Near field communication based wireless data transmission is demonstrated to reflect a practical approach of the sensor to measure lactate concentration portably using human perspiration. PMID:27465437

  4. Bendable Electro-chemical Lactate Sensor Printed with Silver Nano-particles

    PubMed Central

    Abrar, Md Abu; Dong, Yue; Lee, Paul Kyuheon; Kim, Woo Soo

    2016-01-01

    Here we report a flexible amperometric lactate biosensor using silver nanoparticle based conductive electrode. Mechanically bendable cross-serpentine-shaped silver electrode is generated on flexible substrate for the mechanical durability such as bending. The biosensor is designed and fabricated by modifying silver electrode with lactate oxidase immobilized by bovine serum albumin. The in-sensor pseudo Ag/AgCl reference electrode is fabricated by chloridization of silver electrode, which evinced its long-term potential stability against a standard commercial Ag/AgCl reference electrode. The amperometric response of the sensor shows linear dependence with lactate concentration of 1~25 mM/L. Anionic selectivity is achieved by using drop-casted Nafion coated on silver electrode against anionic interferences such as ascorbate. This non-invasive electrochemical lactate sensor also demonstrates excellent resiliency against mechanical deformation and temperature fluctuation which leads the possibility of using it on human epidermis for continuous measurement of lactate from sweat. Near field communication based wireless data transmission is demonstrated to reflect a practical approach of the sensor to measure lactate concentration portably using human perspiration. PMID:27465437

  5. Bendable Electro-chemical Lactate Sensor Printed with Silver Nano-particles

    NASA Astrophysics Data System (ADS)

    Abrar, Md Abu; Dong, Yue; Lee, Paul Kyuheon; Kim, Woo Soo

    2016-07-01

    Here we report a flexible amperometric lactate biosensor using silver nanoparticle based conductive electrode. Mechanically bendable cross-serpentine-shaped silver electrode is generated on flexible substrate for the mechanical durability such as bending. The biosensor is designed and fabricated by modifying silver electrode with lactate oxidase immobilized by bovine serum albumin. The in-sensor pseudo Ag/AgCl reference electrode is fabricated by chloridization of silver electrode, which evinced its long-term potential stability against a standard commercial Ag/AgCl reference electrode. The amperometric response of the sensor shows linear dependence with lactate concentration of 1~25 mM/L. Anionic selectivity is achieved by using drop-casted Nafion coated on silver electrode against anionic interferences such as ascorbate. This non-invasive electrochemical lactate sensor also demonstrates excellent resiliency against mechanical deformation and temperature fluctuation which leads the possibility of using it on human epidermis for continuous measurement of lactate from sweat. Near field communication based wireless data transmission is demonstrated to reflect a practical approach of the sensor to measure lactate concentration portably using human perspiration.

  6. Organic electrode coatings for next-generation neural interfaces

    PubMed Central

    Aregueta-Robles, Ulises A.; Woolley, Andrew J.; Poole-Warren, Laura A.; Lovell, Nigel H.; Green, Rylie A.

    2014-01-01

    Traditional neuronal interfaces utilize metallic electrodes which in recent years have reached a plateau in terms of the ability to provide safe stimulation at high resolution or rather with high densities of microelectrodes with improved spatial selectivity. To achieve higher resolution it has become clear that reducing the size of electrodes is required to enable higher electrode counts from the implant device. The limitations of interfacing electrodes including low charge injection limits, mechanical mismatch and foreign body response can be addressed through the use of organic electrode coatings which typically provide a softer, more roughened surface to enable both improved charge transfer and lower mechanical mismatch with neural tissue. Coating electrodes with conductive polymers or carbon nanotubes offers a substantial increase in charge transfer area compared to conventional platinum electrodes. These organic conductors provide safe electrical stimulation of tissue while avoiding undesirable chemical reactions and cell damage. However, the mechanical properties of conductive polymers are not ideal, as they are quite brittle. Hydrogel polymers present a versatile coating option for electrodes as they can be chemically modified to provide a soft and conductive scaffold. However, the in vivo chronic inflammatory response of these conductive hydrogels remains unknown. A more recent approach proposes tissue engineering the electrode interface through the use of encapsulated neurons within hydrogel coatings. This approach may provide a method for activating tissue at the cellular scale, however, several technological challenges must be addressed to demonstrate feasibility of this innovative idea. The review focuses on the various organic coatings which have been investigated to improve neural interface electrodes. PMID:24904405

  7. Submonolayer nucleation and growth and the initial stage of multilayer kinetic roughening during Ag/Ag (100) homoepitaxy

    SciTech Connect

    Zhang, C.

    1996-08-01

    A comprehensive Scanning Tunneling Microscopy (STM) study of submonolayer nucleation and growth of 2D islands in Ag/Ag(100) homoepitaxy for temperature between 295K and 370K is presented. The initial stages of multilayer kinetic roughening is also studied. Analysis of an appropriate model for metal (100) homoepitaxy, produces estimates of 350 meV for the terrace diffusion barrier, 400 meV for the adatom bond energy, and 25 meV for the additional Ehrlich-Schwoebel step-edge barrier.

  8. Non-gassing nickel-cadmium battery electrodes and cells

    NASA Technical Reports Server (NTRS)

    Luksha, E.; Gordy, D. J.

    1972-01-01

    The concept of a negative limited nongassing nickel-cadmium battery was demonstrated by constructing and testing practical size experimental cells of approximately 25 Ah capacity. These batteries operated in a gas-free manner and had measured energy densities of 10-11 Wh/lb. Thirty cells were constructed for extensive testing. Some small cells were tested for over 200 cycles at 100% depth. For example, a small cell with an electrodeposited cadmium active mass on a silver screen still had 55% of its theoretical capacity (initial efficiency was 85%). There was no evidence of deterioration of gassing properties with cycling of the nickel electrodes. The charge temperature was observed to be the most critical variable governing nickel electrode gassing. This variable was shown to be age dependent. Four types of cadmium electrodes were tested: an electrodeposited cadmium active mass on a cadmium or silver substrate, a porous sintered silver substrate based electrode, and a Teflon bonded pressed cadmium electrode. The electrodeposited cadmium mass on a silver screen was found to be the best all-around electrode from a performance point of view and from the point of view of manufacturing them in a size required for a 25 Ah size battery.

  9. Performance of dry electrode with bristle in recording EEG rhythms across brain state changes.

    PubMed

    Kitoko, Vangu; Nguyen, Tuan N; Nguyen, Jordan S; Tran, Yvonne; Nguyen, Hung T

    2011-01-01

    In this paper we evaluate the physiological performance of a silver-silver chloride dry electrode with bristle (B-Electrode) in recording EEG data. For this purpose, we compare the performance of the bristle electrode in recording EEG data with the standard wet gold-plated cup electrode (G-Electrode) using two different brain state change tasks including resting condition with eyes-closed and performing mathematical task with eyes-open. Using a 2 channel recording device, eyes-closed command data were collected from each of 6 participants for a period of 20 sec and the same procedure was applied for the mathematical calculation task. These data were used for statistical and classification analyse. Although, B-electrode has shown a slightly higher performance compared with G-electrode in both tasks, but analyse did not reveal any significant differences between both electrodes in all six subjects tested.

  10. Effective passivation of Ag nanowire-based flexible transparent conducting electrode by TiO2 nanoshell

    NASA Astrophysics Data System (ADS)

    Lee, Dong Geon; Lee, Dongjun; Yoo, Jin Sun; Lee, Sangwook; Jung, Hyun Suk

    2016-08-01

    Silver nanowire-based flexible transparent electrodes have critical problem, in spite of their excellent electrical and optical properties, that the electrical conductance and transparency degrade within several days in air because of oxidation of silver. To prevent the degradation of the silver nanowire, we encapsulated Ag-NWs with thin TiO2 barrier. Bar-coated silver nanowires on flexible polymer substrate were laminated at 120 °C, followed by atomic layer deposition of TiO2 nanoshell. With 20 nm of TiO2 nanoshells on silver nanowires, the transparent electrode keeps its electrical and optical properties over 2 months. Moreover, the TiO2-encapsulated silver nanowire-based transparent electrodes exhibit excellent bending durability.

  11. Successively thresholded domain boundary roughening driven by pinning centers and missing bonds: Hard-spin mean-field theory applied to d=3 Ising magnets.

    PubMed

    Çağlar, Tolga; Berker, A Nihat

    2015-12-01

    Hard-spin mean-field theory has recently been applied to Ising magnets, correctly yielding the absence and presence of an interface roughening transition respectively in d=2 and d=3 dimensions and producing the ordering-roughening phase diagram for isotropic and anisotropic systems. The approach has now been extended to the effects of quenched random pinning centers and missing bonds on the interface of isotropic and anisotropic Ising models in d=3. We find that these frozen impurities cause domain boundary roughening that exhibits consecutive thresholding transitions as a function of interaction anisotropy. For both missing-bond and pinning-center impurities, for moderately large values of the anisotropy, the systems saturate to the "solid-on-solid" limit, exhibiting a single universal curve for the domain boundary width as a function of impurity concentration. PMID:26764656

  12. Surface roughening of silicon, thermal silicon dioxide, and low-k dielectric coral films in argon plasma

    SciTech Connect

    Yin Yunpeng; Sawin, Herbert H.

    2008-01-15

    The surface roughness evolutions of single crystal silicon, thermal silicon dioxide (SiO{sub 2}), and low dielectric constant film coral in argon plasma have been measured by atomic force microscopy as a function of ion bombardment energy, ion impingement angle, and etching time in an inductively coupled plasma beam chamber, in which the plasma chemistry, ion energy, ion flux, and ion incident angle can be adjusted independently. The sputtering yield (or etching rate) scales linearly with the square root of ion energy at normal impingement angle; additionally, the angular dependence of the etching yield of all films in argon plasma followed the typical sputtering yield curve, with a maximum around 60 deg. -70 deg. off-normal angle. All films stayed smooth after etching at normal angle but typically became rougher at grazing angles. In particular, at grazing angles the rms roughness level of all films increased if more material was removed; additionally, the striation structure formed at grazing angles can be either parallel or transverse to the beam impingement direction, which depends on the off-normal angle. More interestingly, the sputtering caused roughness evolution at different off-normal angles can be qualitatively explained by the corresponding angular dependent etching yield curve. In addition, the roughening at grazing angles is a strong function of the type of surface; specifically, coral suffers greater roughening compared to thermal silicon dioxide.

  13. Genetics Home Reference: Silver syndrome

    MedlinePlus

    ... Me Understand Genetics Home Health Conditions Silver syndrome Silver syndrome Enable Javascript to view the expand/collapse boxes. Download PDF Open All Close All Description Silver syndrome belongs to a group of genetic disorders ...

  14. Magnetohydrodynamic electrode

    DOEpatents

    Marchant, David D.; Killpatrick, Don H.

    1978-01-01

    An electrode capable of withstanding high temperatures and suitable for use as a current collector in the channel of a magnetohydrodynamic (MHD) generator consists of a sintered powdered metal base portion, the upper surface of the base being coated with a first layer of nickel aluminide, an intermediate layer of a mixture of nickel aluminide - refractory ceramic on the first layer and a third or outer layer of a refractory ceramic material on the intermediate layer. The sintered powdered metal base resists spalling by the ceramic coatings and permits greater electrode compliance to thermal shock. The density of the powdered metal base can be varied to allow optimization of the thermal conductivity of the electrode and prevent excess heat loss from the channel.

  15. Cermet electrode

    DOEpatents

    Maskalick, Nicholas J.

    1988-08-30

    Disclosed is a cermet electrode consisting of metal particles of nickel, cobalt, iron, or alloys or mixtures thereof immobilized by zirconia stabilized in cubic form which contains discrete deposits of about 0.1 to about 5% by weight of praseodymium, dysprosium, terbium, or a mixture thereof. The solid oxide electrode can be made by covering a substrate with particles of nickel, cobalt, iron, or mixtures thereof, growing a stabilized zirconia solid oxide skeleton around the particles thereby immobilizing them, contacting the skeleton with a compound of praseodymium, dysprosium, terbium, or a mixture thereof, and heating the skeleton to a temperature of at least 500.degree. C. The electrode can also be made by preparing a slurry of nickel, cobalt, iron, or mixture and a compound of praseodymium, dysprosium, terbium, or a mixture thereof, depositing the slurry on a substrate, heating the slurry to dryness, and growing a stabilized zirconia skeleton around the metal particles.

  16. Photoelectrochemical electrodes

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Rembaum, A. (Inventor)

    1983-01-01

    The surface of a moderate band gap semiconductor such as p-type molybdenum sulfide is modified to contain an adherent film of charge mediating ionene polymer containing an electroactive unit such as bipyridimium. Electron transport between the electrode and the mediator film is favorable and photocorrosion and recombination processes are suppressed. Incorporation of particles of catalyst such as platinum within the film provides a reduction in overvoltage. The polymer film is readily deposited on the electrode surface and can be rendered stable by ionic or addition crosslinking. Catalyst can be predispersed in the polymer film or a salt can be impregnated into the film and reduced therein.

  17. A Silver Opportunity.

    ERIC Educational Resources Information Center

    Desser, Debra M.

    1996-01-01

    Presents an assignment that involves forming student companies to determine and defend cost estimates for producing a silver Oscar statuette. Includes an assessment rubric for cooperative effort. (JRH)

  18. Dosimetry using silver salts

    DOEpatents

    Warner, Benjamin P.

    2003-06-24

    The present invention provides a method for detecting ionizing radiation. Exposure of silver salt AgX to ionizing radiation results in the partial reduction of the salt to a mixture of silver salt and silver metal. The mixture is further reduced by a reducing agent, which causes the production of acid (HX) and the oxidized form of the reducing agent (R). Detection of HX indicates that the silver salt has been exposed to ionizing radiation. The oxidized form of the reducing agent (R) may also be detected. The invention also includes dosimeters employing the above method for detecting ionizing radiation.

  19. Synthesis and characterization of silver-polypyrrole film composite

    NASA Astrophysics Data System (ADS)

    Ayad, Mohamad. M.; Zaki, Eman

    2009-11-01

    In this work, we report the chemical polymerization of pyrrole to obtain thin film of polypyrrole (PPy) hydrochloride deposited onto the electrode of the quartz crystal microbalance (QCM). The film in the base form was exposed to a solution of AgNO 3. Electroless reduction for silver ions by the PPy film took place and silver particles were adsorbed onto the film surface. The silver particles content at the PPy films were analyzed by QCM and the results showed that the concentrations of silver uptakes increase as the original AgNO 3 solution increases. The morphology of the surface of the PPy film and the silver-PPy film composite were studied by the scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). They showed that the obtained silver particles have spherical, cubic and tetrahedral structures. X-ray diffraction (XRD) and Fourier transformed infra-red spectroscopy (FTIR) were used to characterize the structure of the powder composite. This work reveals the capability of PPy film coating on QCM in sensing and removing silver from several environmental samples.

  20. The fate of nano-silver in aqueous media

    NASA Astrophysics Data System (ADS)

    Plowman, Blake. J.; Tschulik, Kristina; Walport, Emily; Young, Neil P.; Compton, Richard G.

    2015-07-01

    Silver nanoparticles offer highly attractive properties for many applications, however concern has been raised over the possible toxicity of this material in environmental systems. While it is thought that the release of Ag+ can play a crucial role in this toxicity, the mechanism by which the oxidative dissolution of nano-silver occurs is not yet understood. Here we address this through the electrochemical analysis of gold-core silver-shell nanoparticles in various solutions. This novel method allows the direct quantification of silver dissolution by normalisation to the gold core signal. This is shown to be highly effective at discriminating between silver dissolution and the loss of nanoparticles from the electrode surface. We evidence through this rigorous approach that the reduction of O2 drives the dissolution of nano-silver, while in the presence of Cl- this dissolution is greatly inhibited. This work is extended to the single nanoparticle level using nano-impact experiments.Silver nanoparticles offer highly attractive properties for many applications, however concern has been raised over the possible toxicity of this material in environmental systems. While it is thought that the release of Ag+ can play a crucial role in this toxicity, the mechanism by which the oxidative dissolution of nano-silver occurs is not yet understood. Here we address this through the electrochemical analysis of gold-core silver-shell nanoparticles in various solutions. This novel method allows the direct quantification of silver dissolution by normalisation to the gold core signal. This is shown to be highly effective at discriminating between silver dissolution and the loss of nanoparticles from the electrode surface. We evidence through this rigorous approach that the reduction of O2 drives the dissolution of nano-silver, while in the presence of Cl- this dissolution is greatly inhibited. This work is extended to the single nanoparticle level using nano-impact experiments

  1. Transparent metal electrodes from ordered nanosphere arrays

    NASA Astrophysics Data System (ADS)

    Morfa, Anthony J.; Akinoglu, Eser M.; Subbiah, Jegadesan; Giersig, Michael; Mulvaney, Paul

    2013-08-01

    We show that perforated metal electrode arrays, fabricated using nanosphere lithography, provide a viable alternative to conductive metal oxides as transparent electrode materials. The inter-aperture spacing is tuned by varying etching times in an oxygen plasma, and the effect of inter-aperture "wire" thickness on the optical and electronic properties of perforated silver films is shown. Optical transmission is limited by reflection and surface plasmons, and for these results do not exceed 73%. Electrical sheet resistance is shown to be as low as 3 Ω ◻-1 for thermally evaporated silver films. The performance of organic photovoltaic devices comprised of a P3HT:PCBM bulk heterojunction deposited onto perforated metal arrays is shown to be limited by optical transmission, and a simple model is presented to overcome these limitations.

  2. Part 1. Conducting polymer: Experimental aspects of piezoelectric quartz crystal oscillator and electrodeposited polyvinylferrocene (PVF) film system. Part 2. Voltammetric studies of nitrate and nitrite ions at rotating silver disk and electrochemical quartz crystal microbalance electrodes

    SciTech Connect

    Mensah, E.A.

    1993-01-01

    The experimental aspects of the electrochemical quartz crystal microbalance (EQCM) and the quartz crystal microbalance (QCM) techniques have been studied. These two techniques were applied to the investigation of polyvinylferrocene (PVF) film(s) on gold (Au) substrate. Additionally the EQCM and the Ag rotating disk electrodes were employed in tandem to investigate nitrate/nitrite reduction in basic and acidic media. In Chapter 2, a broad historical perspective of QCM, its application in the vacuum community, and the extended use in various liquids and hence the exploitation of the beneficial characteristics for electrochemical purposes (EQCM), are discussed. Chapter 3 treats the relatively new, yet established field of conducting polymer. Imbued in this chapter is the discussion of electrodeposition, rigidity determination, and characterization of PVF film. The studies of electroreduction of nitrate and nitrite ions are examined in chapters 4 and 5. Reduction in a basic solution is discussed in chapter 4, while chapter 5 looks at reduction in an acid medium.

  3. Construction and analytical applications of an extractive electrode sensitive to mercury(I).

    PubMed

    Baiulescu, G E; Ciocan, N

    1977-01-01

    The construction and characteristics of a new type of extractive electrode sensitive to Hg(2+)(2) are described. The performance of the electrode is compared with that of an ion-selective electrode with mercurous dithizonate as the active substance. The Hg(2+)(2) -extractive electrode contains Pd(HDz)(2) in its membrane. Its stability and sensitivity are remarkable. It has been used as indicator electrode for the titration of halides alone and in mixtures, and for determination of mercury(I), mercury(II), silver, and of substances containing or reacting with mercury. The basis of the electrode response is discussed.

  4. The silver ions contribution into the cytotoxic activity of silver and silver halides nanoparticles

    NASA Astrophysics Data System (ADS)

    Klimov, A. I.; Zherebin, P. M.; Gusev, A. A.; Kudrinskiy, A. A.; Krutyakov, Y. A.

    2015-11-01

    The biocidal action of silver nanoparticles capped with sodium citrate and silver halides nanoparticles capped with non-ionic surfactant polyoxyethylene(20)sorbitan monooleate (Tween 80®) against yeast cells Saccharomyces cerevisiae was compared to the effect produced by silver nitrate and studied through the measurement of cell loss and kinetics of K+ efflux from the cells. The cytotoxicity of the obtained colloids was strongly correlated with silver ion content in the dispersions. The results clearly indicated that silver and silver halides nanoparticles destroyed yeast cells through the intermediate producing of silver ions either by dissolving of salts or by oxidation of silver.

  5. Laser patterning of platinum electrodes for safe neurostimulation

    NASA Astrophysics Data System (ADS)

    Green, R. A.; Matteucci, P. B.; Dodds, C. W. D.; Palmer, J.; Dueck, W. F.; Hassarati, R. T.; Byrnes-Preston, P. J.; Lovell, N. H.; Suaning, G. J.

    2014-10-01

    Objective. Laser surface modification of platinum (Pt) electrodes was investigated for use in neuroprosthetics. Surface modification was applied to increase the surface area of the electrode and improve its ability to transfer charge within safe electrochemical stimulation limits. Approach. Electrode arrays were laser micromachined to produce Pt electrodes with smooth surfaces, which were then modified with four laser patterning techniques to produce surface structures which were nanosecond patterned, square profile, triangular profile and roughened on the micron scale through structured laser interference patterning (SLIP). Improvements in charge transfer were shown through electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and biphasic stimulation at clinically relevant levels. A new method was investigated and validated which enabled the assessment of in vivo electrochemically safe charge injection limits. Main results. All of the modified surfaces provided electrical advantage over the smooth Pt. The SLIP surface provided the greatest benefit both in vitro and in vivo, and this surface was the only type which had injection limits above the threshold for neural stimulation, at a level shown to produce a response in the feline visual cortex when using an electrode array implanted in the suprachoroidal space of the eye. This surface was found to be stable when stimulated with more than 150 million clinically relevant pulses in physiological saline. Significance. Critical to the assessment of implant devices is accurate determination of safe usage limits in an in vivo environment. Laser patterning, in particular SLIP, is a superior technique for improving the performance of implant electrodes without altering the interfacial electrode chemistry through coating. Future work will require chronic in vivo assessment of these electrode patterns.

  6. The Silver Bullet Syndrome.

    ERIC Educational Resources Information Center

    Dehne, George C.

    1995-01-01

    Many colleges address complex problems with a single "silver bullet" strategy. Because value shifts according to the consumer's situation or goal, private colleges should become more aware of their "situational value" and exploit it. This requires an understanding of how students choose colleges. In contrast, popular silver bullets target…

  7. Recovery of silver from CEPOD anolyte solutions

    SciTech Connect

    Blanchard, D.L.; Surma, J.E.; Alexander, D.L.; Shade, E.H.; Matheson, J.D.; Cochran, D.L.; Wheelwright, E.J.; Boyd, T.

    1994-09-01

    The process known as Catalyzed Electrochemical Plutonium Oxide Dissolution (CEPOD) has been shown effective for removing plutonium from a variety of residues and solids. This process involves the electrochemical oxidation of PuO{sub 2} (and other Pu species) to (PuO{sub 2}){sup 2+}, and dissolution of the latter species in the anode solution (anolyte). Silver is used to transfer charge from the electrodes to the solid Pu oxide. Ag (1) is oxidized at the anode to Ag(II) and carried by the solution to the plutonium oxide solids, where the silver and oxide undergo a redox reaction that converts Pu(IV) to Pu(VI), and Ag(II) to Ag(I). Other metal ions [such as Ce(IV) and Co(III)] may also be used for this charge transfer, but have been found to be less effective than silver. The same process may be used to destroy various organic materials (such as paper and wood, oil and fuels, and synthetic polymer materials) by complete oxidation to CO{sub 2} or H{sub 2}O, for example. Upon completion of a CEPOD dissolver run, the anolyte may be processed to remove solution species of interest (i.e., Pu), or the anolyte may be recycled, or disposed. Because silver is a Resource Conservation and Recovery Act (RCRA) land ban material, it must be removed from waste streams. Preliminary experiments, completed in FY 1991, demonstrated a simple, effective technique for silver removal from solutions. Ascorbic acid (C{sub 6}H{sub 8}O{sub 6}) Was Used to reduce silver ion to metallic silver, which precipitates from solution. The process was demonstrated effective on a bench scale using samples of actual CEPOD anolyte. Further experiments, in FY 1993, optimized these parameters and demonstrated the effectiveness of the technique on CEPOD anolyte on a larger, process scale (liters of solution). This report describes both the preliminary bench-scale experiments and the more recent process-scale experiments. The results are also compared to electro-deposition, another method of silver ion removal.

  8. Femtosecond laser direct writing of microholes on roughened ZnO for output power enhancement of InGaN light-emitting diodes.

    PubMed

    Zang, Zhigang; Zeng, Xiaofeng; Du, Jihe; Wang, Ming; Tang, Xiaosheng

    2016-08-01

    A significant enhancement of light extraction efficiency from InGaN light-emitting diodes (LEDs) with microhole arrays and roughened ZnO was experimentally demonstrated. The roughened ZnO was fabricated using an Ar and H2 plasma treatment of ZnO films pre-coated on a p-GaN layer. When followed by a femtosecond laser direct writing technique, a periodic array of microholes could be added to the surface. The diameter of the microhole was varied by changing the output power of the femtosecond laser. Compared to conventional LEDs on the same wafer, the output power of LEDs with roughened ZnOs and a microhole (diameter of 2 μm) array was increased by 58.4% when operated with an injection current of 220 mA. Moreover, it was found that LEDs fabricated with roughened ZnO and the microhole array had similar current-voltage (I-V) characteristics to those of conventional LEDs and no degrading effect was observed.

  9. Femtosecond laser direct writing of microholes on roughened ZnO for output power enhancement of InGaN light-emitting diodes.

    PubMed

    Zang, Zhigang; Zeng, Xiaofeng; Du, Jihe; Wang, Ming; Tang, Xiaosheng

    2016-08-01

    A significant enhancement of light extraction efficiency from InGaN light-emitting diodes (LEDs) with microhole arrays and roughened ZnO was experimentally demonstrated. The roughened ZnO was fabricated using an Ar and H2 plasma treatment of ZnO films pre-coated on a p-GaN layer. When followed by a femtosecond laser direct writing technique, a periodic array of microholes could be added to the surface. The diameter of the microhole was varied by changing the output power of the femtosecond laser. Compared to conventional LEDs on the same wafer, the output power of LEDs with roughened ZnOs and a microhole (diameter of 2 μm) array was increased by 58.4% when operated with an injection current of 220 mA. Moreover, it was found that LEDs fabricated with roughened ZnO and the microhole array had similar current-voltage (I-V) characteristics to those of conventional LEDs and no degrading effect was observed. PMID:27472594

  10. Impact of etching kinetics on the roughening of thermal SiO{sub 2} and low-k dielectric coral films in fluorocarbon plasmas

    SciTech Connect

    Yin Yunpeng; Sawin, Herbert H.

    2007-07-15

    The impact of etching kinetics and etching chemistries on surface roughening was investigated by etching thermal silicon dioxide and low-k dielectric coral materials in C{sub 4}F{sub 8}/Ar plasma beams in an inductive coupled plasma beam reactor. The etching kinetics, especially the angular etching yield curves, were measured by changing the plasma pressure and the feed gas composition which influence the effective neutral-to-ion flux ratio during etching. At low neutral-to-ion flux ratios, the angular etching yield curves are sputteringlike, with a peak around 60 deg. -70 deg. off-normal angles; the surface at grazing ion incidence angles becomes roughened due to ion scattering related ion-channeling effects. At high neutral-to-ion flux ratios, ion enhanced etching dominates and surface roughening at grazing angles is mainly caused by the local fluorocarbon deposition induced micromasking mechanism. Interestingly, the etched surfaces at grazing angles remain smooth for both films at intermediate neutral-to-ion flux ratio regime. Furthermore, the oxygen addition broadens the region over which the etching without roughening can be performed.

  11. Method for the recovery of silver from silver zeolite

    DOEpatents

    Reimann, George A.

    1986-01-01

    High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

  12. Method for the recovery of silver from silver zeolite

    DOEpatents

    Reimann, G.A.

    1985-03-05

    High purity silver is recovered from silver exchanged zeolite used to capture radioactive iodine from nuclear reactor and nuclear fuel reprocessing environments. The silver exchanged zeolite is heated with slag formers to melt and fluidize the zeolite and release the silver, the radioactivity removing with the slag. The silver containing metallic impurities is remelted and treated with oxygen and a flux to remove the metal impurities. About 98% of the silver in the silver exchanged zeolite having a purity of 99% or better is recoverable by the method.

  13. Silver nanostructures synthesis via optically induced electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Li, Pan; Liu, Na; Yu, Haibo; Wang, Feifei; Liu, Lianqing; Lee, Gwo-Bin; Wang, Yuechao; Li, Wen Jung

    2016-06-01

    We present a new digitally controlled, optically induced electrochemical deposition (OED) method for fabricating silver nanostructures. Projected light patterns were used to induce an electrochemical reaction in a specialized sandwich-like microfluidic device composed of one indium tin oxide (ITO) glass electrode and an optically sensitive-layer-covered ITO electrode. Silver polyhedral nanoparticles, triangular and hexagonal nanoplates, and nanobelts were controllably synthesized in specific positions at which projected light was illuminated. The silver nanobelts had rectangular cross-sections with an average width of 300 nm and an average thickness of 100 nm. By controlling the applied voltage, frequency, and time, different silver nanostructure morphologies were obtained. Based on the classic electric double-layer theory, a dynamic process of reduction and crystallization can be described in terms of three phases. Because it is template- and surfactant-free, the digitally controlled OED method facilitates the easy, low cost, efficient, and flexible synthesis of functional silver nanostructures, especially quasi-one-dimensional nanobelts.

  14. Silver nanostructures synthesis via optically induced electrochemical deposition

    PubMed Central

    Li, Pan; Liu, Na; Yu, Haibo; Wang, Feifei; Liu, Lianqing; Lee, Gwo-Bin; Wang, Yuechao; Li, Wen Jung

    2016-01-01

    We present a new digitally controlled, optically induced electrochemical deposition (OED) method for fabricating silver nanostructures. Projected light patterns were used to induce an electrochemical reaction in a specialized sandwich-like microfluidic device composed of one indium tin oxide (ITO) glass electrode and an optically sensitive-layer-covered ITO electrode. Silver polyhedral nanoparticles, triangular and hexagonal nanoplates, and nanobelts were controllably synthesized in specific positions at which projected light was illuminated. The silver nanobelts had rectangular cross-sections with an average width of 300 nm and an average thickness of 100 nm. By controlling the applied voltage, frequency, and time, different silver nanostructure morphologies were obtained. Based on the classic electric double-layer theory, a dynamic process of reduction and crystallization can be described in terms of three phases. Because it is template- and surfactant-free, the digitally controlled OED method facilitates the easy, low cost, efficient, and flexible synthesis of functional silver nanostructures, especially quasi-one-dimensional nanobelts. PMID:27295084

  15. The development of a micropatterned electrode for studies of zinc electrodeposition

    SciTech Connect

    Sutija, D.P.; Muller, R.H.; Tobias, C.W.

    1986-12-01

    A micropatterned electrode was prepared for the study of electrocrystallization. Using microphotolithography, in conjunction with evaporation and pulse electrodeposition of thin films, a set of artificially roughened electrodes with hemispherical surface features five microns in diameter was developed. Voltammetric studies were conducted to determine the best electrode material. Gold, platinum, and various carbon surfaces were evaluated for zinc nucleation density and hydrogen overpotential. Surface homogeneity was examined by both light and scanning electron microscopy. Gold was determined to possess the best combination of material properties: chemical inertness, low melting point, and a high work function allowing underpotential deposition of zinc which reduces the rate of hydrogen evolution. Stripping coulometry was employed to determine zinc limiting currents, and evaluate effective diffusion coefficients in concentrated zinc chloride solutions. Although the method worked well for dilute zinc chloride and copper sulfate solutions, it failed at higher current densities; the emergence of surface roughness obscured actual limiting current plateaus.

  16. Microwave dielectric properties and chemical compatibility with silver electrode of Li2TiO3 ceramic with Li2O-ZnO-B2O3 glass additive

    NASA Astrophysics Data System (ADS)

    Sayyadi-Shahraki, A.; Taheri-Nassaj, E.; Hassanzadeh-Tabrizi, S. A.; Barzegar-Bafrooei, H.

    2015-01-01

    The effects of Li2O-ZnO-B2O3 (LZB) glass additive on the sintering behavior, phase composition, microstructure and microwave dielectric properties of Li2TiO3 (LT) ceramics have been investigated. The addition of a small amount of LZB glass can reduce the sintering temperature of LT ceramics from 1150 °C to 900 °C without obvious degradation of the microwave dielectric properties. Only a single-phase Li2TiO3 is formed in LT ceramic with LZB glass addition sintered at 900 °C for 2 h. Typically, the 2.5 wt% LZB glass-added LT ceramic sintered at 900 °C for 2 h can reach a maximum relative density of 94.8% of the theoretical density and exhibits good microwave dielectric properties of εr=22.9, Qf=59,600 GHz and τf=+23.7 ppm/°C. The XRD, SEM and EDX analyses showed that the ceramic can be co-fired well with Ag electrode, which may be applied for LTCC application.

  17. Tensile bond strength of resin-bonded non-precious alloys with chemically and mechanically roughened surfaces.

    PubMed

    Isidor, F; Hassna, N M; Josephsen, K; Kaaber, S

    1991-10-01

    The present study was carried out for investigation of the tensile bond strength of resin-bonded non-precious alloys after their surfaces were roughened by sand-blasting, chemical etching, or sugar crystal impressions. Fifty test specimens were cast in a Ni-Cr (Wiron 88) alloy and 50 in a Co-Cr (Wirobond) alloy. Twenty specimens of each alloy were surface-treated according to the sugar crystal impression method. The remaining specimens were first sand-blasted, and 20 specimens of each alloy were thereafter allocated for chemical etching and divided into subgroups with different etching conditions. The samples were chemically etched in strong inorganic acid solutions. After being etched, the specimens were bonded together in pairs by a chemically-curing resin cement (Panavia EX) with a force of 2 kg/cm2. After cementation, the specimens were stored under humid conditions at 37 degrees C for three wk. Prior to being tested, the specimens were subjected to 1000 thermal cyclings at temperatures between 10 degrees C and 55 degrees C. The tensile bond strength tests showed that Ni-Cr specimens sand-blasted and thereafter etched with a 50% conc. of HNO3 and a 50% conc. of HCl for two min and Co-Cr specimens sand-blasted and etched (conc. HCl for 15 min or three h) or sand-blasted alone resulted in similar high bonding values ranging between 33.3 and 37.2 MPa. Surface roughening with use of the sugar crystal impression method resulted in statistically significant lower bond strength values for both alloys (Ni-Cr, 17.9 MPa; Co-Cr, 10.2 MPa).

  18. Silver(II) Oxide or Silver(I,III) Oxide?

    ERIC Educational Resources Information Center

    Tudela, David

    2008-01-01

    The often called silver peroxide and silver(II) oxide, AgO or Ag[subscript 2]O[subscript 2], is actually a mixed oxidation state silver(I,III) oxide. A thermochemical cycle, with lattice energies calculated within the "volume-based" thermodynamic approach, explain why the silver(I,III) oxide is more stable than the hypothetical silver(II) oxide.…

  19. Mineral commodity profiles: Silver

    USGS Publications Warehouse

    Butterman, W.C.; Hilliard, Henry E.

    2005-01-01

    Overview -- Silver is one of the eight precious, or noble, metals; the others are gold and the six platinum-group metals (PGM). World mine production in 2001 was 18,700 metric tons (t) and came from mines in 60 countries; the 10 leading producing countries accounted for 86 percent of the total. The largest producer was Mexico, followed by Peru, Australia, and the United States. About 25 percent of the silver mined in the world in 2001 came from silver ores; 15 percent, from gold ores and the remaining 60 percent, from copper, lead, and zinc ores. In the United States, 14 percent of the silver mined in 2001 came from silver ores; 39 percent, from gold ores; 10 percent, from copper and copper-molybdenum ores; and 37 percent, from lead, zinc, and lead-zinc ores. The precious metal ores (gold and silver) came from 30 lode mines and 10 placer mines; the base-metal ores (copper, lead, molybdenum, and zinc) came from 24 lode mines. Placer mines yielded less than 1 percent of the national silver production. Silver was mined in 12 States, of which Nevada was by far the largest producer; it accounted for nearly one-third of the national total. The production of silver at domestic mines generated employment for about 1,100 mine and mill workers. The value of mined domestic silver was estimated to be $290 million. Of the nearly 27,000 t of world silver that was fabricated in 2001, about one-third went into jewelry and silverware, one-fourth into the light-sensitive compounds used in photography, and nearly all the remainder went for industrial uses, of which there were 7 substantial uses and many other small-volume uses. By comparison, 85 percent of the silver used in the United States went to photography and industrial uses, 8 percent to jewelry and silverware, and 7 percent to coins and medals. The United States was the largest consumer of silver followed by India, Japan, and Italy; the 13 largest consuming countries accounted for nearly 90 percent of the world total. In the

  20. Roll-to-roll printed silver nanowires for increased stability of flexible ITO-free organic solar cell modules

    NASA Astrophysics Data System (ADS)

    Dos Reis Benatto, Gisele A.; Roth, Bérenger; Corazza, Michael; Søndergaard, Roar R.; Gevorgyan, Suren A.; Jørgensen, Mikkel; Krebs, Frederik C.

    2015-12-01

    We report the use of roll-to-roll printed silver nanowire networks as front electrodes for fully roll-to-roll processed flexible indium-tin-oxide (ITO) free OPV modules. We prepared devices with two types of back electrodes, a simple PEDOT:PSS back electrode and a PEDOT:PSS back electrode with a printed silver grid in order to simultaneously explore the influence of the back electrode structure on the operational stability of the modules that did not include any UV-protection. We subjected the devices to stability testing under a number of protocols recommended by the international summit on OPV stability (ISOS). We explored accelerated ISOS-D-2, ISOS-D-3, ISOS-L-2, ISOS-L-3, ISOS-O-1 and ISOS-O-2 testing protocols and compared the performance to previous reports employing the same testing protocols on devices with PEDOT:PSS instead of the silver nanowires in the front electrode. We find significantly increased operational stability across all ISOS testing protocols over the course of the study and conclude that replacement of PEDOT:PSS in the front electrode with silver nanowires increase operational stability by up to 1000%. The duration of the tests were in the range of 140-360 days. The comparison of front and back electrode stability in this study shows that the modules with silver nanowire front electrodes together with a composite back electrode comprising PEDOT:PSS and a silver grid present the best operational stability.

  1. Fabrication of interdigitated electrodes by inkjet printing technology for apllication in ammonia sensing

    NASA Astrophysics Data System (ADS)

    Dam Le, Duy; Nhien Nguyen, Thi Ngoc; Chanh Tin Doan, Duc; Dung Dang, Thi My; Chien Dang, Mau

    2016-06-01

    In this paper interdigitated electrodes for gas sensors were fabricated by inkjet printing technology. Silver electrodes were inkjet printed on Si/SiO2 substrates instead of traditional photolithography method. The inkjet printing parameters to obtain desired dimensions, thickness of the electrodes and distance between the interdigitated electrodes were optimized in this study. The fabricated interdigitated silver electrodes were tested for application in ammonia gas sensors. Conductive polyaniline (PANI) layer was coated on the silver interdigitated electrodes by drop-coating. Ammonia detection of the PANI-coated chips was characterized with a gas measurement system in which humidity and ammonia concentrations were well-controlled. The electrical conductivity of the PANI films coated on the electrodes was measured when the PANI films were exposed to nitrogen and ammonia. The conductivity of the PANI films decreased significantly due to the deprotonation process of PANI upon ammonia expodure. The recovery time was about 15 min by heating up the polymer chip at 60 °C. The results showed that the silver electrodes fabricated by inkjet printing technique could be used as a sensor platform for ammonia detection.

  2. Synthesis of silver nanoparticles by electron irradiation of silver acetate

    NASA Astrophysics Data System (ADS)

    Li, Yue; Kim, Yong Nam; Lee, Eun Je; Cai, Wei Ping; Cho, Sung Oh

    2006-10-01

    A novel and facile route to synthesize crystalline silver nanoparticles is presented, which is based on electron irradiation technique. Only by irradiating an electron beam onto silver acetate precursor material, silver nanocrystals with the sizes of 15-40 nm were synthesized. The morphology and chemical composition of the irradiated samples were characterized by SEM, TEM, XRD and EELS. The precursor material was decomposed by the energetic electrons and consequently the chemical composition of the material was changed. As the electron fluence was gradually increased, the precursor was converted to silver (I) oxide and finally into silver nanocrystals. Thus, besides silver nanoparticles, silver oxide film can also be synthesized using the electron irradiation technique by controlling the electron fluence. The technique can be useful for mass production of silver nanoparticles and for patterned silver nanoparticle film.

  3. Observing ``quantized'' conductance steps in silver sulfide: Two parallel resistive switching mechanisms

    NASA Astrophysics Data System (ADS)

    Wagenaar, Jelmer J. T.; Morales-Masis, Monica; van Ruitenbeek, Jan M.

    2012-01-01

    We demonstrate that it is possible to distinguish two conductance switching mechanisms in silver sulfide devices at room temperature. Experiments were performed using a Ag2S thin film deposited on a wide Ag bottom electrode, which was contacted by the Pt tip of a scanning tunneling microscope. By applying a positive voltage on the silver electrode, the conductance is seen to switch to a state having three orders of magnitude higher conductance, which is related to the formation of a conductive path inside the Ag2S thin film. We argue this to be composed of a metallic silver nanowire accompanied by a modification of the surrounding lattice structure. Metallic silver nanowires decaying after applying a negative voltage allow observing conductance steps in the breaking traces characteristic for atomic-scale contacts, while the lattice structure deformation is revealed by gradual and continuously decreasing conductance traces.

  4. Activity coefficients of aqueous sodium chloride from 15° to 50°C measured with a glass electrode

    USGS Publications Warehouse

    Truesdell, A.H.

    1968-01-01

    Values of the mean activity coefficient of sodium chloride at 15°, 25°, 38° and 50°C were determined for aqueous NaCl solutions of 0.01 to 1.0 molal from electromotive force measurements on the cell: (sodium-sensitive glass electrode, aqueous sodium chloride, silver chloride-silver).

  5. Silver recovery system data

    SciTech Connect

    Boulineau, B.

    1991-08-26

    In August of 1990 the Savannah River Site Photography Group began testing on a different type of silver recovery system. This paper describes the baseline study and the different phases of installation and testing of the system.

  6. Give silver a shine.

    PubMed

    Fromm, Katharina M

    2011-02-01

    Katharina M. Fromm explains how, as well as catalysis and jewellery, silver serves a myriad of medicinal applications--some of which are even behind poetic traditions such as throwing coins in wishing wells. PMID:21258393

  7. Contribution to the study of the electric arc: Erosion of metallic electrodes. Thesis

    NASA Technical Reports Server (NTRS)

    Castro, A.

    1986-01-01

    A procedure is described for determining the extent of arc electrode erosion (excluding erosion due to transfer of material) from measurements of emitted spectral beam intensity. The relation between emission intensity and plasma temperature is ascertained. Experimental study of several combinations of monometallic electrodes shows that the method is suitable for determining cathode erosion, although the anode metal affects the extent of erosion. Combinations of electrodes which lead to low erosion of silver are reported.

  8. Circumventing Traditional Conditioning Protocols in Polymer Membrane-Based Ion-Selective Electrodes.

    PubMed

    Rich, Michelle; Mendecki, Lukasz; Mensah, Samantha T; Blanco-Martinez, Enrique; Armas, Stephanie; Calvo-Marzal, Percy; Radu, Aleksandar; Chumbimuni-Torres, Karin Y

    2016-09-01

    Preparation of ion-selective electrodes (ISEs) often requires long and complicated conditioning protocols limiting their application as tools for in-field measurements. Herein, we eliminated the need for electrode conditioning by loading the membrane cocktail directly with primary ion solution. This proof of concept experiment was performed with iodide, silver, and sodium selective electrodes. The proposed methodology significantly shortened the preparation time of ISEs, yielding functional electrodes with submicromolar detection limits. Moreover, it is anticipated that this approach may form the basis for the development of miniaturized all-solid-state ion-selective electrodes for in situ measurements. PMID:27523089

  9. Circumventing Traditional Conditioning Protocols in Polymer Membrane-Based Ion-Selective Electrodes.

    PubMed

    Rich, Michelle; Mendecki, Lukasz; Mensah, Samantha T; Blanco-Martinez, Enrique; Armas, Stephanie; Calvo-Marzal, Percy; Radu, Aleksandar; Chumbimuni-Torres, Karin Y

    2016-09-01

    Preparation of ion-selective electrodes (ISEs) often requires long and complicated conditioning protocols limiting their application as tools for in-field measurements. Herein, we eliminated the need for electrode conditioning by loading the membrane cocktail directly with primary ion solution. This proof of concept experiment was performed with iodide, silver, and sodium selective electrodes. The proposed methodology significantly shortened the preparation time of ISEs, yielding functional electrodes with submicromolar detection limits. Moreover, it is anticipated that this approach may form the basis for the development of miniaturized all-solid-state ion-selective electrodes for in situ measurements.

  10. Hybrid electrode based on carbon nanotube and graphene for ultraviolet light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Seo, Tae Hoon; Lee, Gun Hee; Park, Sungchan; Chandramohan, S.; Park, Ah Hyun; Cho, Hyunjin; Park, Min; Jong Kim, Myung; Suh, Eun-Kyung

    2015-10-01

    We report on a transparent current-spreading electrode that combines carbon nanotubes (CNTs) and graphene for UV-LEDs. We compared the device performance and long-term stability of this CNT-graphene hybrid electrode (CGE) with those of the silver nanowire-graphene electrode (SGE) reported previously. Both types of electrode offered excellent UV transmittance and reduced sheet resistance through the bridging effect for grain boundaries and defects in graphene by nanotubes or nanowires. UV-LEDs using such electrodes offered reduced forward voltage and enhanced electroluminescence intensity, but the device with the CGE showed excellent stability whereas the SGE degraded with time.

  11. A new method for measuring low resistivity contacts between silver and YBa2Cu3O(7-x) superconductor

    NASA Technical Reports Server (NTRS)

    Hsi, Chi-Shiung; Haertling, Gene H.; Sherrill, Max D.

    1991-01-01

    Several methods of measuring contact resistivity between silver electrodes and YBa2Cu3O(7-x) superconductors were investigated; including the two-point, the three point, and the lap-joint methods. The lap-joint method was found to yield the most consistent and reliable results and is proposed as a new technique for this measurement. Painting, embedding, and melting methods were used to apply the electrodes to the superconductor. Silver electrodes produced good ohmic contacts to YBa2Cu3O(7-x) superconductors with contact resistivities as low as 1.9 x 10 to the -9th ohm sq cm.

  12. Anodic Stripping Voltammetry of Silver Nanoparticles: Aggregation Leads to Incomplete Stripping

    PubMed Central

    Cloake, Samantha J; Toh, Her Shuang; Lee, Patricia T; Salter, Chris; Johnston, Colin; Compton, Richard G

    2015-01-01

    The influence of nanoparticle aggregation on anodic stripping voltammetry is reported. Dopamine-capped silver nanoparticles were chosen as a model system, and melamine was used to induce aggregation in the nanoparticles. Through the anodic stripping of the silver nanoparticles that were aggregated to different extents, it was found that the peak area of the oxidative signal corresponding to the stripping of silver to silver(I) ions decreases with increasing aggregation. Aggregation causes incomplete stripping of the silver nanoparticles. Two possible mechanisms of ‘partial oxidation’ and ‘inactivation’ of the nanoparticles are proposed to account for this finding. Aggregation effects must be considered when anodic stripping voltammetry is used for nanoparticle detection and quantification. Hence, drop casting, which is known to lead to aggregation, is not encouraged for preparing electrodes for analytical purposes. PMID:25861566

  13. Novel flexible Dry multipin electrodes for EEG: Signal quality and interfacial impedance of Ti and TiN coatings.

    PubMed

    Fiedler, P; Fonseca, C; Pedrosa, P; Martins, A; Vaz, F; Griebel, S; Haueisen, J

    2013-01-01

    Conventional Silver/Silver-Chloride electrodes are inappropriate for routine high-density EEG and emerging new fields of application like brain computer interfaces. A novel multipin electrode design is proposed. It enables rapid and easy application while maintaining signal quality and patient comfort. The electrode design is described and impedance and EEG tests are performed with Titanium and Titanium Nitride coated electrodes. The results are compared to conventional reference electrodes in a multi-volunteer study. The calculated signal parameters prove the multipin electrode concept to reproducibly acquire EEG signal quality comparable to Ag/AgCl electrodes. The promising results encourage further investigation and can provide a technological base for future preparation-free multichannel EEG systems.

  14. Stacking faults and interface roughening in semipolar (202{sup ¯}1{sup ¯}) single InGaN quantum wells for long wavelength emission

    SciTech Connect

    Wu, Feng; Zhao, Yuji; DenBaars, Steven P.; Nakamura, Shuji; Speck, James S.; Romanov, Alexey

    2014-04-14

    The microstructure of InGaN single quantum wells (QWs) grown in semipolar (202{sup ¯}1{sup ¯}) orientation on GaN substrates was studied by transmission electron microscopy. Stress relaxation in the lattice mismatch In{sub x}Ga{sub 1−x}N layer was realized by forming partial misfit dislocations associated with basal plane stacking faults (BPSFs). For given composition x = 0.24, BPSFs formation was observed when the QW thickness exceeded 4 nm. The high density of partial threading dislocations that bound the BPSFs is detrimental to light-emitting device performance. Interface roughening (faceting) was observed for both upper and lower QW interfaces (more pronounced for upper interface) and was found to increase with the thickness of the QW. BPSFs had a tendency to nucleate at roughened interface valleys.

  15. Leaching of Silver from Silver-Impregnated Food Storage Containers

    ERIC Educational Resources Information Center

    Hauri, James F.; Niece, Brian K.

    2011-01-01

    The use of silver in commercial products has proliferated in recent years owing to its antibacterial properties. Food containers impregnated with micro-sized silver promise long food life, but there is some concern because silver can leach out of the plastic and into the stored food. This laboratory experiment gives students the opportunity to…

  16. resterilizable electrode for electrosurgery

    NASA Technical Reports Server (NTRS)

    Engstrom, E. R.; Houge, J. C.

    1979-01-01

    Required properties of flexibility, electrical conductivity, tensile strength, and tear resistance of electrosurgical electrodes is retained through utilization of flexible-polymer/conductive particle composites for electrodes.

  17. Continuum model of surface roughening and epitaxial breakdown during low-temperature Ge(001) molecular beam epitaxy

    SciTech Connect

    Bratland, K. A.; Spila, T.; Cahill, D. G.; Greene, J. E.; Desjardins, P.

    2011-03-15

    Numerical simulations based on a discrete model describing step edge motion are used to compute the surface morphological evolution of Ge(001) layers deposited by low-temperature (T{sub s} = 45-230 deg. C) molecular beam epitaxy and to probe the relationship between surface roughening and the onset of epitaxial breakdown - the abrupt growth mode transition from epitaxial to amorphous - at temperature-dependent critical film thicknesses h{sub 1}(T{sub s}). Computed surface widths w and in-plane coherence lengths d as a function of layer thickness h exhibit good agreement with experimental values. Inspired by experimental results indicating that epitaxial breakdown is initiated at facetted interisland trenches as the surface roughness reaches a T{sub s}-independent overall aspect ratio, we show that simulated data for w/d = 0.03 correspond to thicknesses h{sub 1{proportional_to}} exp (-E{sub 1}/kT{sub s}) with E{sub 1} = 0.63 eV, a value equal to the Ge adatom diffusion activation energy on Ge(001). Simulated h{sub 1} values agree well with experimental data. Above a critical growth temperature of 170 deg. C, computed w/d values saturate at large film thicknesses, never reaching the critical aspect ratio w/d = 0.03. Thus, the model also predicts that epitaxial breakdown does not occur for T{sub s} > 170 deg. C as observed experimentally.

  18. Measurement of local convective heat transfer coefficients from a smooth and roughened NACA-0012 airfoil: Flight test data

    NASA Technical Reports Server (NTRS)

    Newton, James E.; Vanfossen, G. James; Poinsatte, Phillip E.; Dewitt, Kenneth J.

    1988-01-01

    Wind tunnels typically have higher free stream turbulence levels than are found in flight. Turbulence intensity was measured to be 0.5 percent in the NASA Lewis Icing Research Tunnel (IRT) with the cloud making sprays off and around 2 percent with cloud making equipment on. Turbulence intensity for flight conditions was found to be too low to make meaningful measurements for smooth air. This difference between free stream and wing tunnel conditions has raised questions as to the validity of results obtained in the IRT. One objective of these tests was to determine the effect of free stream turbulence on convective heat transfer for the NASA Lewis LEWICE ice growth prediction code. These tests provide in-flight heat transfer data for a NASA-0012 airfoil with a 533 cm chord. Future tests will measure heat transfer data from the same airfoil in the Lewis Icing Research Tunnel. Roughness was obtained by the attachment of small, 2 mm diameter hemispheres of uniform size to the airfoil in three different patterns. Heat transfer measurements were recorded in flight on the NASA Lewis Twin Otter Icing Research Aircraft. Measurements were taken for the smooth and roughened surfaces at various aircraft speeds and angles of attack up to four degrees. Results are presented as Frossling number versus position on the airfoil for various roughnesses and angles of attack.

  19. Low Impedance Carbon Adhesive Electrodes with Long Shelf Life.

    PubMed

    Posada-Quintero, Hugo F; Reyes, Bersaín A; Burnham, Ken; Pennace, John; Chon, Ki H

    2015-10-01

    A novel electrocardiogram (ECG) electrode film is developed by mixing carbon black powder and a quaternary salt with a visco-elastic polymeric adhesive. Unlike traditional wet gel-based electrodes, carbon/salt/adhesive (CSA) electrodes should theoretically have an infinite shelf life as they do not dehydrate even after a prolonged period of storage. The CSA electrodes are electrically activated for use through the process of electrophoresis. Specifically, the activation procedure involves sending a high voltage and current through the electrode, which results in significant reduction of impedance so that high fidelity ECG signals can be obtained. Using the activation procedure, the ideal concentration of carbon black powder in the mixture with the adhesive was examined. It was determined that the optimum concentration of carbon black which minimized post-activation impedance was 10%. Once the optimal carbon black powder concentration was determined, extensive signal analysis was performed to compare the performance of the CSA electrodes to the standard silver-silver chloride (Ag/AgCl) electrodes. As a part of data analysis, electrode-skin contact impedance of the CSA was measured and compared to the standard Ag/AgCl electrodes; we found consistently lower impedance for CSA electrodes. For quantitative data analysis, we simultaneously collected ECG data with CSA and Ag/AgCl electrodes from 17 healthy subjects. Heart rate variability (HRV) indices and ECG morphological waveforms were calculated to compare CSA and Ag/AgCl electrodes. Non-significant differences for most of the HRV indices between CSA and Ag/AgCl electrodes were found. Of the morphological waveform metrics consisting of R-wave peak amplitude, ST-segment elevation and QT interval, only the first index was found to be significantly different between the two media. The response of CSA electrodes to motion artifacts was also tested, and we found in general no difference in the quality of the ECG signal

  20. Ion-Selective Electrodes.

    ERIC Educational Resources Information Center

    Arnold, Mark A.; Meyerhoff, Mark E.

    1984-01-01

    Literature on ion-selective electrodes (ISEs) is reviewed in seven sections: books, conferences, reviews; potentiometric membrane electrodes; glass and solid-state membrane electrodes; liquid and polymer membrane ISEs; coated wire electrodes, ion-selective field effect transistors, and microelectrodes; gas sensors and selective bioelectrode…

  1. Design of dual working electrodes for concentration process in metalloimmunoassay.

    PubMed

    Hori, Nobuyasu; Chikae, Miyuki; Kirimura, Hiroya; Takamura, Yuzuru

    2016-10-01

    Electrochemical immunosensing, particularly through a metalloimmunoassay, is a promising approach for development of point-of-care (POC) diagnostics devices. This study investigated the structure of dual working electrodes (W1 and W2), used in a silver nanoparticles-labeled sandwich-type immunoassay and silver concentration process, paying special attention to the position of W1 relative to W2. The new structures of the dual working electrodes were fabricated for efficient silver concentration and evaluated experimentally, which showed that the duration of prereduction before current measurement decreased from 480 s to 300 s by transforming the position of W1 from 1 line to 2 lines or 6 parts. The experimental results were also compared with numerical simulations based on three-dimensional diffusion, and the prereduction step almost followed the three-dimensional diffusion equation. Using numerical simulations, the ideal structures of dual working electrodes were designed based on relationships between the structures and duration of prereduction or the LOD. In the case of 36 lines at an area ratio of W1 to W1 + W2 of 1 to 10, the prereduction duration decreased to 96 s. The dual working electrodes designed in this study promise to shorten the total analysis time and lower the LOD for POC diagnostics. PMID:27572238

  2. Electrochemical Study and Applications of Selective Electrodeposition of Silver on Quantum Dots.

    PubMed

    Martín-Yerga, Daniel; Rama, Estefanía Costa; Costa-García, Agustín

    2016-04-01

    In this work, selective electrodeposition of silver on quantum dots is described. The particular characteristics of the nanostructured silver thus obtained are studied by electrochemical and microscopic techniques. On one hand, quantum dots were found to catalyze the silver electrodeposition, and on the other hand, a strong adsorption between electrodeposited silver and quantum dots was observed, indicated by two silver stripping processes. Nucleation of silver nanoparticles followed different mechanisms depending on the surface (carbon or quantum dots). Voltammetric and confocal microscopy studies showed the great influence of electrodeposition time on surface coating, and high-resolution transmission electron microscopy (HRTEM) imaging confirmed the initial formation of Janus-like Ag@QD nanoparticles in this process. By use of moderate electrodeposition conditions such as 50 μM silver, -0.1 V, and 60 s, the silver was deposited only on quantum dots, allowing the generation of localized nanostructured electrode surfaces. This methodology can also be employed for sensing applications, showing a promising ultrasensitive electrochemical method for quantum dot detection.

  3. Protein-Modified-Paramagnetic-Particles as a Tool for Detection of Silver(I) Ions

    NASA Astrophysics Data System (ADS)

    Kizek, R.; Krizkova, S.; Adam, V.; Huska, D.; Hubalek, J.; Trnkova, L.

    2009-04-01

    In a number of published articles the toxic effect of silver(I) ions on aquatic organisms is described. Silver(I) ions in aquatic environment are stable in a wide range of pH. Under alkali pH AgOH and Ag(OH)2- can be formed. However, in water environment there are many compounds to interact with silver(I) ions. The most important ones are chloride anions, which forms insoluble precipitate with silver(I) ions (AgCl). The insoluble silver containing compounds do not pose any threat to aquatic organisms. Toxicity of silver ions is probably caused by their very good affinity to nucleic acids and also proteins. The binding into active enzyme site leads to the expressive enzyme reaction inhibition. Silver(I) ions are into living environment introduced thanks to anthropogenic activities. They easily contaminate atmosphere as well as aquatic environment or soils. Several authors described using of carbon electrode as working electrode for determination of silver. Recently, we have suggested heavy metal biosensor based on interaction of metal ions with low molecular mass protein called metallothionein (MT), which was adsorbed on the surface of hanging mercury drop electrode (HMDE). The biosensor was successfully used for detection of cadmium(II) and zinc(II) ions, cisplatin, cisplatin-DNA adducts and palladium(II) ions. Due to the convincing results with MT as biological component we report on suggesting of heavy metal biosensor based on immobilization of metallothionein (MT) on the surface of carbon paste electrode (CPE) via MT-antibodies. Primarily we studied of basic electrochemical behaviour of MT at surface of carbon paste electrode by using of square wave voltammetry (SWV). Detection limit (3 S/N) for MT was evaluated as 0.1 μg/ml. After that we have evaluated the electroactivity of MT at surface of SWV, we aimed our attention on the way of capturing of MT on the surface of CPE. We choose antibody against MT obtained from chicken eggs for these purposes. Antibodies

  4. HSPES membrane electrode assembly

    NASA Technical Reports Server (NTRS)

    Kindler, Andrew (Inventor); Yen, Shiao-Ping (Inventor)

    2000-01-01

    An improved fuel cell electrode, as well as fuel cells and membrane electrode assemblies that include such an electrode, in which the electrode includes a backing layer having a sintered layer thereon, and a non-sintered free-catalyst layer. The invention also features a method of forming the electrode by sintering a backing material with a catalyst material and then applying a free-catalyst layer.

  5. Kinetic surface roughening and wafer bow control in heteroepitaxial growth of 3C-SiC on Si(111) substrates

    PubMed Central

    Wang, Li; Walker, Glenn; Chai, Jessica; Iacopi, Alan; Fernandes, Alanna; Dimitrijev, Sima

    2015-01-01

    A thin, chemically inert 3C-SiC layer between GaN and Si helps not only to avoid the “melt-back” effect, but also to inhibit the crack generation in the grown GaN layers. The quality of GaN layer is heavily dependent on the unique properties of the available 3C-SiC/Si templates. In this paper, the parameters influencing the roughness, crystalline quality, and wafer bow are investigated and engineered to obtain high quality, low roughness 3C-SiC/Si templates suitable for subsequent GaN growth and device processing. Kinetic surface roughening and SiC growth mechanisms, which depend on both deposition temperature and off-cut angle, are reported for heteroepitaxial growth of 3C-SiC on Si substrates. The narrower terrace width on 4° off-axis Si enhances the step-flow growth at 1200 °C, with the roughness of 3C-SiC remaining constant with increasing thickness, corresponding to a scaling exponent of zero. Crack-free 3C-SiC grown on 150-mm Si substrate with a wafer bow of less than 20 μm was achieved. Both concave and convex wafer bow can be obtained by in situ tuning of the deposited SiC layer thicknesses. The 3C-SiC grown on off-axis Si, compared to that grown on on-axis Si, has lower surface roughness, better crystallinity, and smaller bow magnitude. PMID:26487465

  6. Kinetic surface roughening and wafer bow control in heteroepitaxial growth of 3C-SiC on Si(111) substrates.

    PubMed

    Wang, Li; Walker, Glenn; Chai, Jessica; Iacopi, Alan; Fernandes, Alanna; Dimitrijev, Sima

    2015-10-21

    A thin, chemically inert 3C-SiC layer between GaN and Si helps not only to avoid the "melt-back" effect, but also to inhibit the crack generation in the grown GaN layers. The quality of GaN layer is heavily dependent on the unique properties of the available 3C-SiC/Si templates. In this paper, the parameters influencing the roughness, crystalline quality, and wafer bow are investigated and engineered to obtain high quality, low roughness 3C-SiC/Si templates suitable for subsequent GaN growth and device processing. Kinetic surface roughening and SiC growth mechanisms, which depend on both deposition temperature and off-cut angle, are reported for heteroepitaxial growth of 3C-SiC on Si substrates. The narrower terrace width on 4° off-axis Si enhances the step-flow growth at 1200 °C, with the roughness of 3C-SiC remaining constant with increasing thickness, corresponding to a scaling exponent of zero. Crack-free 3C-SiC grown on 150-mm Si substrate with a wafer bow of less than 20 μm was achieved. Both concave and convex wafer bow can be obtained by in situ tuning of the deposited SiC layer thicknesses. The 3C-SiC grown on off-axis Si, compared to that grown on on-axis Si, has lower surface roughness, better crystallinity, and smaller bow magnitude.

  7. Fatigue Debonding of the Roughened Stem–Cement Interface: Effects of Surface Roughness and Stem Heating Conditions

    PubMed Central

    Damron, Leatha A.; Kim, Do-Gyoon; Mann, Kenneth A.

    2007-01-01

    The aim of this study was to determine the effects of cyclic loading on the debond process of a roughened stem– cement interface used in total hip arthroplasty. The specific goals were to assess the effects of two surgeon-controlled variables (stem heating and degree of stem surface roughness) and to determine if an independent finite element-based fracture mechanics model could be used to predict the debond response. A clamped cantilever beam geometry was used to determine the fatigue debond response of the stem– cement interface and was created using an experimental mold that simulated in vivo cementing conditions. A second experiment was performed using a torsion-loading model representative of the stem– cement–bone composite. For both experiments, two stem heating (room temperature and 50°C) and surface roughness conditions (grit blasted: Ra = 2.3 and 5.1 μm) were used. Finally, a finite element model of the torsion experiment with provision for crack growth was developed and compared with the experimental results. Results from both experiments revealed that neither stem preheating nor use of a stem with a greater surface roughness had a marked effect on the fatigue debond response. There was substantial variability in the debond response for all cases; this may be due to microscopic gaps at the interface for all interface conditions. The debond rate from the finite element simulation (10−7.31 m/cycle) had a magnitude similar to the experimental torsion model (10− (6.77 ± 1.25) m/cycle). This suggests that within the context of the experimental conditions studied here that the debond response could be assessed using a linear elastic fracture mechanics-type approach. PMID:16292769

  8. Fatigue debonding of the roughened stem-cement interface: effects of surface roughness and stem heating conditions.

    PubMed

    Damron, Leatha A; Kim, Do-Gyoon; Mann, Kenneth A

    2006-07-01

    The aim of this study was to determine the effects of cyclic loading on the debond process of a roughened stem-cement interface used in total hip arthroplasty. The specific goals were to assess the effects of two surgeon-controlled variables (stem heating and degree of stem surface roughness) and to determine if an independent finite element-based fracture mechanics model could be used to predict the debond response. A clamped cantilever beam geometry was used to determine the fatigue debond response of the stem-cement interface and was created using an experimental mold that simulated in vivo cementing conditions. A second experiment was performed using a torsion-loading model representative of the stem-cement-bone composite. For both experiments, two stem heating (room temperature and 50 degrees C) and surface roughness conditions (grit blasted: Ra = 2.3 and 5.1 microm) were used. Finally, a finite element model of the torsion experiment with provision for crack growth was developed and compared with the experimental results. Results from both experiments revealed that neither stem preheating nor use of a stem with a greater surface roughness had a marked effect on the fatigue debond response. There was substantial variability in the debond response for all cases; this may be due to microscopic gaps at the interface for all interface conditions. The debond rate from the finite element simulation (10(-7.31) m/cycle) had a magnitude similar to the experimental torsion model (10(-(6.77 +/- 1.25)) m/cycle). This suggests that within the context of the experimental conditions studied here that the debond response could be assessed using a linear elastic fracture mechanics-type approach.

  9. Tales From Silver Lands.

    ERIC Educational Resources Information Center

    Finger, Charles J.

    In 1925, "Tales From Silver Lands" was awarded the Newbery medal as the most distinguished contribution to American children's literature for the year. The book contains a collection of 19 short stories learned from the Indians of South America as the author traveled to different lands. As described on the dust jacket, the tales are about "strange…

  10. Potassium silver cyanide

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 28 , 2010 , the assessment summary for potassium silver cyanide is inclu

  11. Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

    NASA Astrophysics Data System (ADS)

    Kvitek, L.; Panacek, A.; Prucek, R.; Soukupova, J.; Vanickova, M.; Kolar, M.; Zboril, R.

    2011-07-01

    The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much more lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms.

  12. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  13. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  14. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  15. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  16. 21 CFR 73.2500 - Silver.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Silver. 73.2500 Section 73.2500 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2500 Silver. (a) Identity. (1) The color additive, silver, is a crystalline powder of high purity silver prepared by the reaction of silver nitrate with...

  17. Oxygen reduction on Ni, Ag, and Cu meniscus electrodes in molten carbonate

    SciTech Connect

    Ogura, Hiroyuki; Shirogami, Tamotsu

    1994-12-31

    The oxygen reduction pathways in molten carbonates have been investigated by analyzing the charge transfer resistances of the i-V curves on the meniscus electrodes of Ni, Cu, and Ag screens at 550 C. The electrochemical reduction pathways of oxygen at the meniscus electrode were found to be different depending on the electrode materials. For the Ni meniscus electrode system, the reactive material of charge transfer is the lithium doped nickel oxide, for the Ag system that is the silver oxide ion, and for the Cu system that is peroxide ion, respectively.

  18. Screen-Printable Silver Pastes with Nanosized Glass Frits for Silicon Solar Cells

    NASA Astrophysics Data System (ADS)

    Shih, Yu-Chou; Lin, Yeong-Her; You, Jiun-Pyng; Shi, Frank G.

    2013-03-01

    In this study, silver pastes containing different sizes of glass frits were employed to form the front-side electrodes in order to examine the size effect of the glass frits on the interfacial microstructures between the front-side silver contacts and the n-type silicon emitter layers, which will subsequently affect the electrical performance of silicon solar cells. The interfacial microstructures at the Ag/Si interfaces were investigated by advanced electron microscopy techniques. The transfer length method (TLM) was used to measure the specific contact resistivity of silver electrodes screen-printed on the n-type silicon substrates. The particle size of the glass frits was found to strongly affect the interfacial microstructures and therefore resulted in different specific contact resistivities ( ρ c) of the fabricated silver ohmic contacts. Nanosized glass frits showed excellent etching ability during engineered thermal treatments. The samples made with silver pastes containing microsized glass frits showed a thick residual glass layer at the Ag/Si interface, while the silver paste with nanosized glass frits was found to form an interface with less glass residue, which led to lower resistance after otherwise identical processing.

  19. Micromachined electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.

    2007-12-11

    An electrode array is disclosed which has applications for neural stimulation and sensing. The electrode array, in certain embodiments, can include a plurality of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. In other embodiments of the electrode array, the electrodes can be fixed to the substrate. The electrode array can be formed from a combination of bulk and surface micromachining, and can include electrode tips having an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis.

  20. Flexible retinal electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.; Christenson, Todd R.

    2006-10-24

    An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

  1. Controlled porosity in electrodes

    SciTech Connect

    Chiang, Yet-Ming; Bae, Chang-Jun; Halloran, John William; Fu, Qiang; Tomsia, Antoni P.; Erdonmez, Can K.

    2015-06-23

    Porous electrodes in which the porosity has a low tortuosity are generally provided. In some embodiments, the porous electrodes can be designed to be filled with electrolyte and used in batteries, and can include low tortuosity in the primary direction of ion transport during charge and discharge of the battery. In some embodiments, the electrodes can have a high volume fraction of electrode active material (i.e., low porosity). The attributes outlined above can allow the electrodes to be fabricated with a higher energy density, higher capacity per unit area of electrode (mAh/cm.sup.2), and greater thickness than comparable electrodes while still providing high utilization of the active material in the battery during use. Accordingly, the electrodes can be used to produce batteries with high energy densities, high power, or both compared to batteries using electrodes of conventional design with relatively highly tortuous pores.

  2. Characterization of Electrochemically Generated Silver

    NASA Technical Reports Server (NTRS)

    Adam, Niklas; Martinez, James; Carrier, Chris

    2014-01-01

    Silver biocide offers a potential advantage over iodine, the current state of the art in US spacecraft disinfection technology, in that silver can be safely consumed by the crew. Low concentrations of silver (<500 ppb) have been shown to kill bacteria in water systems and keep it safe for potability. Silver does not require hardware to remove it from a water system, and therefore can provide a simpler means for disinfecting water. The Russian segment of the International Space Station has utilized an electrochemically generated silver solution, which is colloidal in nature. To be able to reliably provide a silver biocide to drinking water by electrochemical means would reduce mass required for removing another biocide such as iodine from the water. This would also aid in crew time required to replace iodine removal cartridges. Future long term missions would benefit from electrochemically produced silver as the biocide could be produced on demand and requires only a small concentration to be effective. Since it can also be consumed safely, there is less mass in removal hardware and little consumables required for production. The goal of this project initially is to understand the nature of the electrochemically produced silver, the particle sizes produced by the electrochemical cell and the effect that voltage adjustment has on the particle size. In literature, it has been documented that dissolved oxygen and pH have an effect on the ionization of the electrochemical silver so those parameters would be measured and possibly adjusted to understand their effect on the silver.

  3. Advanced silver zinc battery development for the SRB and ET range safety subsystems

    NASA Technical Reports Server (NTRS)

    Adamedes, Zoe

    1994-01-01

    This document presents in viewgraph format the design and development of silver zinc (AgZn) batteries for the solid rocket booster (SRB) and external tank (ET) range safety subsystems. Various engineering techniques, including composite separator systems, new electrode processing techniques, and new restraint techniques, were used to meet difficult requirements.

  4. High performance cermet electrodes

    DOEpatents

    Isenberg, Arnold O.; Zymboly, Gregory E.

    1986-01-01

    Disclosed is a method of increasing the operating cell voltage of a solid oxide electrochemical cell having metal electrode particles in contact with an oxygen-transporting ceramic electrolyte. The metal electrode is heated with the cell, and oxygen is passed through the oxygen-transporting ceramic electrolyte to the surface of the metal electrode particles so that the metal electrode particles are oxidized to form a metal oxide layer between the metal electrode particles and the electrolyte. The metal oxide layer is then reduced to form porous metal between the metal electrode particles and the ceramic electrolyte.

  5. Characterization of nanoporous gold electrodes for bioelectrochemical applications.

    PubMed

    Scanlon, Micheál D; Salaj-Kosla, Urszula; Belochapkine, Serguei; MacAodha, Domhnall; Leech, Dónal; Ding, Yi; Magner, Edmond

    2012-01-31

    The high surface areas of nanostructured electrodes can provide for significantly enhanced surface loadings of electroactive materials. The fabrication and characterization of nanoporous gold (np-Au) substrates as electrodes for bioelectrochemical applications is described. Robust np-Au electrodes were prepared by sputtering a gold-silver alloy onto a glass support and subsequent dealloying of the silver component. Alloy layers were prepared with either a uniform or nonuniform distribution of silver and, post dealloying, showed clear differences in morphology on characterization with scanning electron microscopy. Redox reactions under kinetic control, in particular measurement of the charge required to strip a gold oxide layer, provided the most accurate measurements of the total electrochemically addressable electrode surface area, A(real). Values of A(real) up to 28 times that of the geometric electrode surface area, A(geo), were obtained. For diffusion-controlled reactions, overlapping diffusion zones between adjacent nanopores established limiting semi-infinite linear diffusion fields where the maximum current density was dependent on A(geo). The importance of measuring the surface area available for the immobilization was determined using the redox protein, cyt c. The area accessible to modification by a biological macromolecule, A(macro), such as cyt c was reduced by up to 40% compared to A(real), demonstrating that the confines of some nanopores were inaccessible to large macromolecules due to steric hindrances. Preliminary studies on the preparation of np-Au electrodes modified with osmium redox polymer hydrogels and Myrothecium verrucaria bilirubin oxidase (MvBOD) as a biocathode were performed; current densities of 500 μA cm(-2) were obtained in unstirred solutions. PMID:22004670

  6. Positive-electrode current collector for liquid-metal cells

    DOEpatents

    Shimotake, H.; Bartholme, L.G.

    1982-09-27

    A current collector for the positive electrode of an electrochemical cell with a positive electrode including a sulfide. The cell also has a negative electrode and a molten salt electrolyte including halides of a metal selected from the alkali metals and the alkaline earth metals in contact with both the positive and negative electrodes. The current collector has a base metal of copper, silver, gold, aluminum or alloys thereof with a coating thereon of iron, nickel, chromium or alloys thereof. The current collector when subjected to cell voltage forms a sulfur-containing compound on the surface thereby substantially protecting the current collector from further attack by sulfur ions during cell operation. Both electroless and electrolytic processes may be used to deposit coatings.

  7. Positive electrode current collector for liquid metal cells

    DOEpatents

    Shimotake, Hiroshi; Bartholme, Louis G.

    1984-01-01

    A current collector for the positive electrode of an electrochemical cell with a positive electrode including a sulfide. The cell also has a negative electrode and a molten salt electrolyte including halides of a metal selected from the alkali metals and the alkaline earth metals in contact with both the positive and negative electrodes. The current collector has a base metal of copper, silver, gold, aluminum or alloys thereof with a coating thereon of iron, nickel, chromium or alloys thereof. The current collector when subjected to cell voltage forms a sulfur-containing compound on the surface thereby substantially protecting the current collector from further attack by sulfur ions during cell operation. Both electroless and electrolytic processes may be used to deposit coatings.

  8. Transparent composite electrode for high-efficiency polymer LEDs

    NASA Astrophysics Data System (ADS)

    Li, Lu; Yu, Zhibin; Liang, Jiajie; Chang, Chia-Hao; Hu, Weili; Pei, Qibing

    2012-09-01

    Polymer composite electrodes based on silver nanowires or carbon nanotubes have been prepared with transparency and surface conductivity approaching those of ITO/glass and better than ITO/PET. The conductive surface has an average roughness less than 10 nm, better than ITO/glass. Depending on the polymer matrix selected, the composite electrodes can be made rigid, flexible like polycarbonate, or stretchable like a rubber. Various polymer light emitting diodes,light emitting electrochemical cells and polymer solar cells have been fabricated using the composite electrode as anode, exhibiting electroluminescent efficiencies generally higher than control devices fabricated on ITO/glass. These polymer light emitting devices are all highly flexible and can be bent to less than 3 mm radius without loss of performance. With further modification of the composite electrodes, we have also demonstrated stretchable OLEDs wherein the emissive area can be elongated by as much as 50%.

  9. Electroencephalogram measurement using polymer-based dry microneedle electrode

    NASA Astrophysics Data System (ADS)

    Arai, Miyako; Nishinaka, Yuya; Miki, Norihisa

    2015-06-01

    In this paper, we report a successful electroencephalogram (EEG) measurement using polymer-based dry microneedle electrodes. The electrodes consist of needle-shaped substrates of SU-8, a silver film, and a nanoporous parylene protective film. Differently from conventional wet electrodes, microneedle electrodes do not require skin preparation and a conductive gel. SU-8 is superior as a structural material to poly(dimethylsiloxane) (PDMS; Dow Corning Toray Sylgard 184) in terms of hardness, which was used in our previous work, and facilitates the penetration of needles through the stratum corneum. SU-8 microneedles can be successfully inserted into the skin without breaking and could maintain a sufficiently low skin-electrode contact impedance for EEG measurement. The electrodes successfully measured EEG from the frontal pole, and the quality of acquired signals was verified to be as high as those obtained using commercially available wet electrodes without any skin preparation or a conductive gel. The electrodes are readily applicable to record brain activities for a long period with little stress involved in skin preparation to the users.

  10. Hydrometallurgical recovery of silver from waste silver oxide button cells

    NASA Astrophysics Data System (ADS)

    Sathaiyan, N.; Nandakumar, V.; Ramachandran, P.

    In recent years, recycling of household batteries has attracted much attention mainly with respect to environmental aspects in addition to the savings. Small silver oxide primary cells used in electric watches become a waste after their life is over. Recycling procedures are needed to prevent any environmental impact from these wastes and to recover the value inherent in the scrap. Smelting and electrolytic methods are discussed for silver recovery from this battery waste. Acid leaching of waste batteries and precipitation of silver as silver chloride followed by smelting at 1000 °C yields a silver recovery of about 83%. An electrolytic route is studied as an alternative to the smelting operation and involves the electrodeposition of silver with higher purity from a silver thiosulfate complex prepared from silver chloride. The electrolysis is potentiostatically controlled at a potential of -0.400 to -0.600 V (SCE) for avoiding side-reactions such as the sulfiding of silver. Although recovery methods have been identified in principle, their suitability for mixed small battery waste and economic factors have yet to be demonstrated.

  11. Enhanced conversion efficiency and surface hydrophobicity of nano-roughened Teflon-like film coated poly-crystalline Si solar cells.

    PubMed

    Lin, Gong-Ru; Meng, Fan-Shuen; Pai, Yi-Hao; Lin, Yung-Hsiang

    2012-03-21

    Nano-roughened Teflon-like film coated poly-crystalline Si photovoltaic solar cells (PVSCs) with enhanced surface hydrophobicity and conversion efficiency (η) are characterized and compared with those coated by a Si nanorod array or a standard SiN anti-reflection layer. The Teflon-like film coated PVSC surface reveals a water contact angle increasing from 89.3° to 96.2° as its thickness enlarges from 22 to 640 nm, which is much larger than those of the standard and Si nanorod array coated PVSC surfaces (with angles of 55.6° and 32.8°, respectively). After nano-roughened Teflon-like film passivation, the PVSC shows a comparable η(10.89%) with the standard SiN coated PVSC (η = 11.39%), while the short-circuit current (I(SC)) is slightly reduced by 2% owing to the slightly decreased UV transmittance and unchanged diode performance. In contrast, the Si nanorod array may offer an improved surface anti-reflection with surface reflectance decreasing from 30% to 5% at a cost of optical scattering and randomized deflection, which simultaneously decrease the optical transmittance from 15% to 3% in the visible region without improving hydrophobicity and conversion efficiency. The Si nanorod array covered PVSC with numerous surface dangling bonds induced by 1 min wet-etching, which greatly reduces the open-circuit voltage (V(OC)) by 10-15% and I(SC) by 30% due to the reduced shunt resistance from 3 to 0.24 kΩ. The nano-scale roughened Teflon-like film coated on PVSC has provided better hydrophobicity and conversion efficiency than the Si nanorod array covered PVSC, which exhibits superior water repellant performance and comparable conversion efficiency to be one alternative approach for self-cleaning PVSC applications. PMID:22323107

  12. Enhanced conversion efficiency and surface hydrophobicity of nano-roughened Teflon-like film coated poly-crystalline Si solar cells.

    PubMed

    Lin, Gong-Ru; Meng, Fan-Shuen; Pai, Yi-Hao; Lin, Yung-Hsiang

    2012-03-21

    Nano-roughened Teflon-like film coated poly-crystalline Si photovoltaic solar cells (PVSCs) with enhanced surface hydrophobicity and conversion efficiency (η) are characterized and compared with those coated by a Si nanorod array or a standard SiN anti-reflection layer. The Teflon-like film coated PVSC surface reveals a water contact angle increasing from 89.3° to 96.2° as its thickness enlarges from 22 to 640 nm, which is much larger than those of the standard and Si nanorod array coated PVSC surfaces (with angles of 55.6° and 32.8°, respectively). After nano-roughened Teflon-like film passivation, the PVSC shows a comparable η(10.89%) with the standard SiN coated PVSC (η = 11.39%), while the short-circuit current (I(SC)) is slightly reduced by 2% owing to the slightly decreased UV transmittance and unchanged diode performance. In contrast, the Si nanorod array may offer an improved surface anti-reflection with surface reflectance decreasing from 30% to 5% at a cost of optical scattering and randomized deflection, which simultaneously decrease the optical transmittance from 15% to 3% in the visible region without improving hydrophobicity and conversion efficiency. The Si nanorod array covered PVSC with numerous surface dangling bonds induced by 1 min wet-etching, which greatly reduces the open-circuit voltage (V(OC)) by 10-15% and I(SC) by 30% due to the reduced shunt resistance from 3 to 0.24 kΩ. The nano-scale roughened Teflon-like film coated on PVSC has provided better hydrophobicity and conversion efficiency than the Si nanorod array covered PVSC, which exhibits superior water repellant performance and comparable conversion efficiency to be one alternative approach for self-cleaning PVSC applications.

  13. Genetics Home Reference: Russell-Silver syndrome

    MedlinePlus

    ... Genetics Home Health Conditions Russell-Silver syndrome Russell-Silver syndrome Enable Javascript to view the expand/collapse ... Download PDF Open All Close All Description Russell-Silver syndrome is a growth disorder characterized by slow ...

  14. Organic devices based on nickel nanowires transparent electrode

    PubMed Central

    Kim, Jeongmo; da Silva, Wilson Jose; bin Mohd Yusoff, Abd. Rashid; Jang, Jin

    2016-01-01

    Herein, we demonstrate a facile approach to synthesize long nickel nanowires and discuss its suitability to replace our commonly used transparent electrode, indium-tin-oxide (ITO), by a hydrazine hydrate reduction method where nickel ions are reduced to nickel atoms in an alkaline solution. The highly purified nickel nanowires show high transparency within the visible region, although the sheet resistance is slightly larger compared to that of our frequently used transparent electrode, ITO. A comparison study on organic light emitting diodes and organic solar cells, using commercially available ITO, silver nanowires, and nickel nanowires, are also discussed. PMID:26804335

  15. Hexacyanoferrate-based composite ion-sensitive electrodes for voltammetry.

    PubMed

    Düssel, H; Dostal, A; Scholz, F

    1996-04-01

    Composite electrodes made of graphite, paraffin and metal hexacyanoferrates exhibit a voltammetric response of the hexacyanoferrate ions, the potential of which depends linearly on the logarithm of concentration of alkali and alkaline-earth metal ions. This behaviour has been observed on account of the fact that the electrochemical reaction is accompanied by an exchange of these ions between the solution and the zeolitic lattice of the hexacyanoferrates for charge compensation. The voltammetric determination of the formal potential of these electrodes in a solution allows the quantitative analysis of the ions which are exchanged between the metal hexacyanoferrates and the aqueous solutions. Iron(III), copper(II), silver(I), nickel(II) and cadmium(II) hexacyanoferrates have been studied for the determination of H(+), Li(+), Na(+), K(+), Rb(+), Cs(+), NH(+)(4), Mg(2+), Ca(2+) and Ba(2+). In some cases, the selectivity constants are as low as 3.10(-4), or even so small that their exact value is inaccessible. Electrodes made of iron (III), copper (II), silver (I), nickel (II) and cadmium (II) hexacyanoferrates are most suitable for the determination of potassium ions. Electrodes with nickel (II) and cadmium (II) hexacyanoferrates are also suitable for the determination of caesium ions. The working range of the electrodes also depends on the conductivity of the solutions and can range from 10(-5) to 1 mol l(-1). Typical standard deviations of the potential measurements are 3 mV.

  16. Silver Ink For Jet Printing

    NASA Technical Reports Server (NTRS)

    Vest, R. W.; Singaram, Saraswathi

    1989-01-01

    Metallo-organic ink containing silver (with some bismuth as adhesion agent) applied to printed-circuit boards and pyrolized in air to form electrically conductive patterns. Ink contains no particles of silver, does not have to be mixed during use to maintain homogeneity, and applied to boards by ink-jet printing heads. Consists of silver neodecanoate and bismuth 2-ethylhexanoate dissolved in xylene and/or toluene.

  17. Initial experiments with flexible conductive electrodes for potential applications in cancer tissue screening

    NASA Astrophysics Data System (ADS)

    Chung, Daehan; Seyfollahi, Sam; Khosla, Ajit; Gray, Bonnie; Parameswaran, Ash; Ramaseshan, Ramani; Kohli, Kirpal

    2011-02-01

    We present initial results on the fabrication and testing of micropatternable conductive nanocomposite polymer (C-NCP) electrodes for tissue impedance measurements. We present these proof-of-concept results as a first step toward the realization of our goal: an improved Electrical Impedance Scanning (EIS) system, whereby tissue can be scanned for cancerous tissue and other anomalies using large arrays of highly flexible microfabricated electrodes. Previous limitations of existing EIS system are addressed by applying polymer based microelectromechanical system (MEMS) technology. In particular, we attempt to minimize mechanical skin contact issues through the use of highly compliant elastomeric polymers, and increase the spatial resolution of measurements through the development of microelectrodes that can be micropatterned into large, highly dense arrays. We accomplish these improvements through the development of C-NCP electrodes that employ silver nanoparticle fillers in an elastomer polymer base that can be easily patterned using conventional soft lithography techniques. These new electrodes are tested on conventional tissue phantoms that mimic the electrical characteristics of human tissue. We characterize the conductivity of the electrodes (average resistivity of 7x10-5 ohm-m +/- 14.3% at 60 wt-% of silver nanoparticles), and further employ the electrodes for impedance characterization via Cole-Cole plots to show that measurements employing C-NCP electrodes are comparable to those obtained with normal macroscopic metal electrodes. We also demonstrate anomaly detection using our highly flexible Ag/AgCl C-NCP electrodes on a tissue phantom.

  18. Improved biomedical electrode

    NASA Technical Reports Server (NTRS)

    Frost, J. D., Jr.

    1972-01-01

    Newly designed electrode is prefilled, disposable, electrolyte-saturated spong. New design permits longe periods of storage without deterioration, and readiness in matter of seconds. Electrodes supply signals for electroencephalogram, electro-oculogram, and electrocardiogram.

  19. Corneal-shaping electrode

    DOEpatents

    Doss, James D.; Hutson, Richard L.

    1982-01-01

    The disclosure relates to a circulating saline electrode for changing corneal shape in eyes. The electrode comprises a tubular nonconductive electrode housing having an annular expanded base which has a surface substantially matched to a subject corneal surface. A tubular conductive electrode connected to a radiofrequency generating source is disposed within the electrode housing and longitudinally aligned therewith. The electrode has a generally hemispherical head having at least one orifice. Saline solution is circulated through the apparatus and over the cornea to cool the corneal surface while radiofrequency electric current emitted from the electrode flows therefrom through the cornea to a second electrode, on the rear of the head. This current heats the deep corneal stroma and thereby effects corneal reshaping as a biological response to the heat.

  20. Dry electrodes for electrocardiography.

    PubMed

    Meziane, N; Webster, J G; Attari, M; Nimunkar, A J

    2013-09-01

    Patient biopotentials are usually measured with conventional disposable Ag/AgCl electrodes. These electrodes provide excellent signal quality but are irritating for long-term use. Skin preparation is usually required prior to the application of electrodes such as shaving and cleansing with alcohol. To overcome these difficulties, researchers and caregivers seek alternative electrodes that would be acceptable in clinical and research environments. Dry electrodes that operate without gel, adhesive or even skin preparation have been studied for many decades. They are used in research applications, but they have yet to achieve acceptance for medical use. So far, a complete comparison and evaluation of dry electrodes is not well described in the literature. This work compares dry electrodes for biomedical use and physiological research, and reviews some novel systems developed for cardiac monitoring. Lastly, the paper provides suggestions to develop a dry-electrode-based system for mobile and long-term cardiac monitoring applications.

  1. MOD silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

    Vest, G. M.; Vest, R. W.

    1984-01-01

    The development of flat plate solar arrays is reported. Photovoltaic cells require back side metallization and a collector grid system on the front surface. Metallo-organic decomposition (MOD) silver films can eliminate most of the present problems with silver conductors. The objectives are to: (1) identify and characterize suitable MO compounds; (2) develop generic synthesis procedures for the MO compounds; (3) develop generic fabrication procedures to screen printable MOD silver inks; (4) optimize processing conditions to produce grid patterns and photovoltaic cells; and (5) develop a model which describes the adhesion between the fired silver film and the silicon surface.

  2. Silver Nanoparticles in Dental Biomaterials

    PubMed Central

    Corrêa, Juliana Mattos; Mori, Matsuyoshi; Sanches, Heloísa Lajas; da Cruz, Adriana Dibo; Poiate, Isis Andréa Venturini Pola

    2015-01-01

    Silver has been used in medicine for centuries because of its antimicrobial properties. More recently, silver nanoparticles have been synthesized and incorporated into several biomaterials, since their small size provides great antimicrobial effect, at low filler level. Hence, these nanoparticles have been applied in dentistry, in order to prevent or reduce biofilm formation over dental materials surfaces. This review aims to discuss the current progress in this field, highlighting aspects regarding silver nanoparticles incorporation, such as antimicrobial potential, mechanical properties, cytotoxicity, and long-term effectiveness. We also emphasize the need for more studies to determine the optimal concentration of silver nanoparticle and its release over time. PMID:25667594

  3. A novel non-enzyme hydrogen peroxide sensor based on catalytic reduction property of silver nanowires.

    PubMed

    Qin, Xia; Wang, Huicai; Miao, Zhiying; Li, Junli; Chen, Qiang

    2015-07-01

    A novel strategy to fabricate a hydrogen peroxide (H2O2) sensor was developed based on silver nanowires modified Pt electrode. The sensor was fabricated by simple casting of silver nanowires (Ag NWs) aqueous solution on a Pt electrode. Silver nanowires were synthesized by an l-cysteine-assisted poly (vinyl pyrrolidone) (PVP)-mediated polyol route. UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to investigate the prepared nanowires. The electrochemical properties of H2O2 sensor were evaluated by cyclic voltammetry (CV) and chronoamperometry. The as-obtained silver nanowires exhibited favorable electroreduction activity toward H2O2, and results indicated that the Ag NWs modified Pt (Ag NWs/Pt) electrode might be gifted from CV scanning with higher surface area and more active sites that afford more effective surface exposure in the electrode-electrolyte interface and consequently improved electrochemical properties. At the applied potential of -0.2V vs. Ag/AgCl, the Ag NWs/Pt electrode as an enzyme-free sensor exhibited a wide linear range of 0.5μM-30mM to H2O2, with a remarkable sensitivity of 9.45μA/mM, a detection limit of 0.2μM estimated at a signal-to-noise ratio of 3 and fast response time (within 5s). Moreover, it showed good reproducibility, anti-interferant ability and long-term stability. The excellent performance of the sensor might be attributed to the well-defined silver nanowires with special catalytic activity.

  4. Angle-specific transparent conducting electrodes with metallic gratings

    SciTech Connect

    Rivolta, N. X. A. Maes, B.

    2014-08-07

    Transparent conducting electrodes, which are not made from indium tin oxide, and which display a strong angular dependence are useful for various technologies. Here, we introduce a tilted silver grating that combines a large conductance with a strong and angle-specific transmittance. When the light incidence angle matches the tilt angle of the grating, transmittance is close to the maximum along a very broadband range. We explain the behavior through simulations that show in detail the plasmonic and interference effects at play.

  5. Compartmented electrode structure

    DOEpatents

    Vissers, Donald R.; Shimotake, Hiroshi; Gay, Eddie C.; Martino, Fredric J.

    1977-06-14

    Electrodes for secondary electrochemical cells are provided with compartments for containing particles of the electrode reactant. The compartments are defined by partitions that are generally impenetrable to the particles of reactant and, in some instances, to the liquid electrolyte used in the cell. During cycling of the cell, reactant material initially loaded into a particular compartment is prevented from migrating and concentrating within the lower portion of the electrode or those portions of the electrode that exhibit reduced electrical resistance.

  6. The CMG Nickel Electrode

    NASA Technical Reports Server (NTRS)

    Depaul, R. A.; Gutridge, I.

    1981-01-01

    The development and design of the Controlled Microgeometry electrode are described. Advantages of the electrode over others in existance include a higher number of ampere hours per kilogram and the ability to make them over a wide range of thicknesses. The parameters that control the performance of the electrode can be individually controlled over a wide range. Therefore, the electrode may be designed to give the optimum performance for a given duty cycle.

  7. A rapid method to estimate the concentration of citrate capped silver nanoparticles from UV-visible light spectra.

    PubMed

    Paramelle, D; Sadovoy, A; Gorelik, S; Free, P; Hobley, J; Fernig, D G

    2014-10-01

    We present a generalized table of extinction coefficient data for silver nanoparticles from 8 to 100 nm. This table allows for easy and quick estimation of the concentration and size of modified and mono-dispersed silver nanoparticles from their optical spectra. We obtained data by determining the silver content of citrate-stabilised silver nanoparticles using sodium cyanide to dissolve the nanoparticles, and measuring solution conductivity with a pH meter and a cyanide-ion selective electrode. The quantification of the silver ion concentration enabled the calculation of extinction coefficients. Experimentally calculated extinction coefficients, in the current work, are in good agreement with collated literature values measured by different authors with non-standardized methodology and each for a limited range of particle size. They are also in good agreement with our theoretical calculations using Mie theory. Thus, we provide a highly standardized and comprehensive tabulated reference data-set.

  8. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, B.E.; Miller, J.L.; Ault, E.R.

    1994-08-23

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window. 2 figs.

  9. Electrically conductive diamond electrodes

    DOEpatents

    Swain, Greg; Fischer, Anne ,; Bennett, Jason; Lowe, Michael

    2009-05-19

    An electrically conductive diamond electrode and process for preparation thereof is described. The electrode comprises diamond particles coated with electrically conductive doped diamond preferably by chemical vapor deposition which are held together with a binder. The electrodes are useful for oxidation reduction in gas, such as hydrogen generation by electrolysis.

  10. Insulated ECG electrodes

    NASA Technical Reports Server (NTRS)

    Portnoy, W. M.; David, R. M.

    1973-01-01

    Insulated, capacitively coupled electrode does not require electrolyte paste for attachment. Other features of electrode include wide range of nontoxic material that may be employed for dielectric because of sputtering technique used. Also, electrode size is reduced because there is no need for external compensating networks with FET operational amplifier.

  11. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, Bruce E.; Miller, John L.; Ault, Earl R.

    1994-01-01

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window.

  12. A Simple Hydrogen Electrode

    ERIC Educational Resources Information Center

    Eggen, Per-Odd

    2009-01-01

    This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements…

  13. Fuel cell electrodes

    SciTech Connect

    Strmcnik, Dusan; Cuesta, Angel; Stamenkovic, Vojislav; Markovic, Nenad

    2015-06-23

    A process includes patterning a surface of a platinum group metal-based electrode by contacting the electrode with an adsorbate to form a patterned platinum group metal-based electrode including platinum group metal sites blocked with adsorbate molecules and platinum group metal sites which are not blocked.

  14. Microresonator electrode design

    DOEpatents

    Olsson, III, Roy H.; Wojciechowski, Kenneth; Branch, Darren W.

    2016-05-10

    A microresonator with an input electrode and an output electrode patterned thereon is described. The input electrode includes a series of stubs that are configured to isolate acoustic waves, such that the waves are not reflected into the microresonator. Such design results in reduction of spurious modes corresponding to the microresonator.

  15. Construction of a new selective coated disk electrode for Ag (I) based on modified polypyrrole-carbon nanotubes composite with new lariat ether.

    PubMed

    Abbaspour, A; Tashkhourian, J; Ahmadpour, S; Mirahmadi, E; Sharghi, H; Khalifeh, R; Shahriyari, M R

    2014-01-01

    A poly (vinyl chloride) (PVC) matrix membrane ion-selective electrode for silver (I) ion is fabricated based on modified polypyrrole - multiwalled carbon nanotubes composite with new lariat ether. This sensor has a Nernstian slope of 59.4±0.5mV/decade over a wide linear concentration range of 1.0×10(-7) to 1.0×10(-1)molL(-1) for silver (I) ion. It has a short response time of about 8.0s and can be used for at least 50days. The detection limit is 9.3×10(-8)molL(-1) for silver (I) ion, and the electrode was applicable in the wide pH range of 1.6 -7.7. The electrode shows good selectivity for silver ion against many cations such as Hg (II), which usually imposes serious interference in the determination of silver ion concentration. The use of multiwalled carbon nanotubes (MWCNTs) in a polymer matrix improves the linear range and sensitivity of the electrode. In addition by coating the solid contact with a layer of the polypyrrole (Ppy) before coating the membrane on it, not only did it reduce the drift in potential, but a shorter response time was also resulted. The proposed electrode was used as an indicator electrode for potentiometric titration of silver ions with chloride anions and in the titration of mixed halides. This electrode was successfully applied for the determination of silver ions in silver sulphadiazine as a burning cream.

  16. Printed silver nanowire antennas with low signal loss at high-frequency radio.

    PubMed

    Komoda, Natsuki; Nogi, Masaya; Suganuma, Katsuaki; Kohno, Kazuo; Akiyama, Yutaka; Otsuka, Kanji

    2012-05-21

    Silver nanowires are printable and conductive, and are believed to be promising materials in the field of printed electronics. However, the resistivity of silver nanowire printed lines is higher than that of metallic particles or flakes even when sintered at high temperatures of 100-400 °C. Therefore, their applications have been limited to the replacement of transparent electrodes made from high-resistivity materials, such as doped metallic oxides, conductive polymers, carbon nanotubes, or graphenes. Here we report that using printed silver nanowire lines, signal losses obtained in the high-frequency radio were lower than those obtained using etched copper foil antennas, because their surfaces were much smoother than those of etched copper foil antennas. This was the case even though the resistivity of silver nanowire lines was 43-71 μΩ cm, which is much higher than that of etched copper foil (2 μΩ cm). When printed silver nanowire antennas were heated at 100 °C, they achieved signal losses that were much lower than those of silver paste antennas comprising microparticles, nanoparticles, and flakes. Furthermore, using a low temperature process, we succeeded in remotely controlling a commercialized radio-controlled car by transmitting a 2.45 GHz signal via a silver nanowire antenna printed on a polyethylene terephthalate film.

  17. Peculiarities of the dielectric response of the silver-modified-zeolite porous microstructure

    NASA Astrophysics Data System (ADS)

    Bunyatova, U.; Ozturk Koc, S.; Orbukh, V. I.; Eyvazova, G. M.; Agamaliev, Z. A.; Lebedeva, N. N.; Koçum, İ. C.; Salamov, B. G.; Ozer, M.

    2016-10-01

    The aim of this study was to characterize electrical conductivity and dielectrical properties of the silver-exchanged zeolite - natural clinoptilolite from Western part of Turkey and Azerbaijan in the range of frequencies from 200 Hz to 1 MHz and at room temperature. For a better understanding the effect of concentration and content of silver in the nanoporous zeolite volume on the conductivity, a study of the dielectric properties of an un-modified and silver-modified zeolite plates with different amounts of Ag ions and Ag nanoparticles is performed. Un-modified and three different types of the silver ion-exchanged modified clinoptilolite plates were prepared. It was found, that with increasing silver concentration, resistance of zeolite plate monotonically decreases at the same time a capacitance is increases. It is suggested an explanation of the observed frequency dependence of the capacitance and resistance of zeolite plates on the silver concentrations may be explain on the basis of an electrode-dielectric interface gap model. At the same time, the observed phenomenon can be explained by considering the fact that with increasing content of silver the conductivity increases. These results show that Ag nanoparticles play significant role for performance improvement in plasma electronic devices with zeolite cathode.

  18. Printed silver nanowire antennas with low signal loss at high-frequency radio.

    PubMed

    Komoda, Natsuki; Nogi, Masaya; Suganuma, Katsuaki; Kohno, Kazuo; Akiyama, Yutaka; Otsuka, Kanji

    2012-05-21

    Silver nanowires are printable and conductive, and are believed to be promising materials in the field of printed electronics. However, the resistivity of silver nanowire printed lines is higher than that of metallic particles or flakes even when sintered at high temperatures of 100-400 °C. Therefore, their applications have been limited to the replacement of transparent electrodes made from high-resistivity materials, such as doped metallic oxides, conductive polymers, carbon nanotubes, or graphenes. Here we report that using printed silver nanowire lines, signal losses obtained in the high-frequency radio were lower than those obtained using etched copper foil antennas, because their surfaces were much smoother than those of etched copper foil antennas. This was the case even though the resistivity of silver nanowire lines was 43-71 μΩ cm, which is much higher than that of etched copper foil (2 μΩ cm). When printed silver nanowire antennas were heated at 100 °C, they achieved signal losses that were much lower than those of silver paste antennas comprising microparticles, nanoparticles, and flakes. Furthermore, using a low temperature process, we succeeded in remotely controlling a commercialized radio-controlled car by transmitting a 2.45 GHz signal via a silver nanowire antenna printed on a polyethylene terephthalate film. PMID:22522460

  19. Effect of prestress on the stability of electrode-electrolyte interfaces during charging in lithium batteries

    NASA Astrophysics Data System (ADS)

    Natsiavas, P. P.; Weinberg, K.; Rosato, D.; Ortiz, M.

    2016-10-01

    We formulate a model of the growth of electrode-electrolyte interfaces in lithium batteries in the presence of an elastic prestress. The model accounts for the kinetics of Li+ transport through a solid electrolyte and, within the interface, for the kinetics of Li+ adsorption by the anode, electrostatics, and the elastic field. We specifically account for the effect of the elastic field through an asymptotic analysis of a nearly flat interface between two semi-infinite elastic bodies. We use the model as a basis for assessing the effect of prestress on the stability of planar growth and the potential of prestress as a means of suppressing the formation of deleterious dendrites. We present a linear stability analysis that results in explicit analytical expressions for the dependence of growth rates, and of the critical unstable wavelength for the interfacial roughening, on the state of prestress and on fundamental parameters such as surface diffusivities, surface energy, deposition kinetics, and elastic moduli. Finally, we examine the model in the light of experimental observations concerned with the effect of applied pressure on a lithium/dioxolane-dimethoxy ethane electrolyte systems. With reasonable choices of parameters and some calibration, the model accounts for the observation that a modest applied pressure indeed results in a substantial reduction in the roughening of the lithium surface during cycling.

  20. Mixed solutions of silver cation and chloride anion in acetonitrile: voltammetric and EQCM study.

    PubMed

    Skompska, Magdalena; Vorotyntsev, Mikhail A; Rajchowska, Aleksandra; Levin, Oleg V

    2010-09-21

    Electrochemical behavior of Pt and Au electrodes in acetonitrile solutions at different concentration ratios of Cl(-) and Ag(+) ions was studied by cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). The composition of the mixed silver chloride solutions, i.e. the amount of each component of the system (solid AgCl and solute species: Ag(+), Cl(-), AgCl(2)(-)), is governed by the solubility product of AgCl and the stability constant of AgCl(2)(-)complex and depends strongly on the ratio of the total concentrations of chloride and silver ions. In this work we analyze in detail the influence of the Cl(-)/Ag(+) concentration ratio on the value of equilibrium electrode potential and the shape of cyclic voltammograms. We explain the complicated shapes of the experimental curves observed at different concentration ranges, propose the mechanisms of the processes occurring at the electrode and substantiate them by EQCM data.

  1. Silver-zinc: status of technology and applications

    NASA Astrophysics Data System (ADS)

    Karpinski, A. P.; Makovetski, B.; Russell, S. J.; Serenyi, J. R.; Williams, D. C.

    Michel Yardney and Professor Henri André developed the first practical silver-zinc battery more than 55 years ago. Since then, primary and rechargeable silver-zinc batteries have attracted a variety of applications due to their high specific energy/energy density, proven reliability and safety, and the highest power output per unit weight and volume of all commercially available batteries. Although significant improvements have been achieved on traditional systems such as lead-acid and nickel/cadmium, and in spite of the advent of new electrochemistries such as lithium-ion and nickel/metal hydride, many users still rely on silver-zinc to satisfy their most demanding and critical requirements. Over the past few years, several of the internal components have been subject to many studies which resulted in significant improvements in the battery wet life and cycle life. Specifically, these include new separator materials which offer an alternative to the cellulosic membranes, improvements to the zinc electrode that include additives that help reduce shape-change and dendritic growth, and to a lesser extent, process changes to the silver electrode and additives to the electrolyte. In comparison, the commonly used secondary systems are lead-acid, nickel/cadmium, nickel/metal hydride, and lithium-ion. Each has attributes which make them desirable for certain applications. Where low cost, high voltage, and high rate capability is required, the lead-acid battery is an obvious choice whenever size and weight are not critical. For applications requiring longer wet life, moderate rate capability, and high cycle life, nickel/cadmium or nickel/metal hydride can be used in spite of their poor charge retention and higher costs. Relatively newer systems are also available such as lithium-ion or lithium polymer technology which are preferred for their high voltage and excellent cycle life. Among the disadvantages of these systems are higher costs, limited configurations (usually

  2. Hybrid surface roughening modes during low-temperature heteroepitaxy: Growth of fully-strained metastable Ge{sub 1-x}Sn{sub x} alloys on Ge(001)2x1

    SciTech Connect

    Desjardins, P.; Spila, T.; Guerdal, O.; Taylor, N.; Greene, J. E.

    1999-12-15

    Fully-strained single-crystal metastable Ge{sub 1-x}Sn{sub x} alloys were grown on Ge(001) up to their critical epitaxial thickness values t{sub epi}(x) in order to probe surface roughening pathways leading to heteroepitaxial breakdown during low-temperature molecular-beam epitaxy under large compressive strain. All films with x>0.09 have comparable roughnesses while films with x<0.09 are considerably rougher with larger lateral feature sizes. Roughening rates increase with increasing x for films with x>0.09 due to a new hybrid relaxation path which only becomes accessible under high strain as kinetic roughening provides surface oscillations on lateral length scales that allow bulk relaxation through strain-induced islanding at growth temperatures where it could not otherwise proceed. (c) 1999 The American Physical Society.

  3. Electronic properties of the silver-silver chloride cluster interface.

    PubMed

    Glaus, Stephan; Calzaferri, Gion; Hoffmann, Roald

    2002-04-15

    The objective of this study was to gain insight into the electronic structure of silver-silver chloride cluster composites and especially into the metal-semiconductor interface. For this purpose a theoretical study of (AgCl)(n) (n=4, 32, 108, 192, and 256), of Ag(m) (m=1-9, 30, 115, 276, and 409), and of the cluster composites Ag(115)-(AgCl)(192) and Ag(409)-(AgCl)(192) has been carried out. Density of levels (DOL), local density of levels (l-DOL), and projection of surface states, as well as projection of properties of individual atoms or groups of atoms obtained in molecular orbital calculations, are shown to be powerful tools for gaining deep insight into the properties of these large systems. The Ag(115)-(AgCl)(192) aggregate, consisting of a cubic Ag(115) cluster without corner atoms on top of a cubic (AgCl)(192) cluster, was found to be remarkably stable with a cluster-to-cluster distance of about 280 pm, and a geometry in which the number of bonding interactions between the silver atoms of Ag(115) and the chloride ions of (AgCl)(192) is at its maximum. A sharp jump in charge distribution occurs at the Ag(115)-(AgCl)(192) composite interface. The first AgCl slab picks up negative charge from the two adjacent silver slabs, so that in total the silver cluster is positively charged. In addition, the core of the silver cluster is positively charged with respect to its outermost layer. The main reason for the charge transfer from the silver cluster to the silver chloride is the newly formed MIGS (metal induced gap states) in the energy-gap range of the silver chloride and the MIdS (metal induced d states) in the d-orbital region. Their wave functions mix with orbitals of the silver cluster and with both the orbitals of the silver and the chloride ions of the silver chloride. The MIGS and the MIdS are of a quite localized nature. In them, nearest neighbor interactions dominate, with the exception of close-lying silver chloride surface states-which mix in to a large

  4. Spark gap electrode erosion

    NASA Astrophysics Data System (ADS)

    Krompholz, H.; Kristiansen, M.

    1984-12-01

    The results of a one-year contract on electrode erosion phenomena are summarized. The arc voltage drop in a spark gap was measured for various electrode, gas, and pressure combinations. A previously developed model of self breakdown voltage distribution was extended. A jet model for electrode erosion was proposed and an experimental arrangement for testing the model was constructed. The effects of inhomogeneities and impurities in the electrodes were investigated. Some of the work described here is scheduled for completion in 1985 under a current grant (AFOSR 84-0032). The areas of investigation described here include: (1) Self breakdown voltage distributions; (2) Electrode erosion; (3) Spark gap voltage recovery.

  5. Spectroelectrochemistry of Silver Deposition on Single Gold Nanocrystals.

    PubMed

    Chirea, Mariana; Collins, Sean S E; Wei, Xingzhan; Mulvaney, Paul

    2014-12-18

    We report the electrodeposition of metallic silver onto gold nanostars adsorbed to ITO electrodes. The electrochemical process was studied at the single particle level by correlated in situ dark field spectroscopy and scanning electron microscopy (SEM). Underpotential deposition avoids bulk silver formation on the ITO substrates. SEM proves that deposition occurs on all surfaces of the gold nanostars when polyvinylpyrrolidone (PVP) is stabilizing the nanostars or preferentially at the nanostar tips when the ligand is removed. The surface plasmon resonance blue-shifts by more than 100 nm following the formation of a 5 nm Ag film on PVP stabilized gold nanostars, moving the scattered color from the near-infrared to red or orange. The spectral shifts can be accurately modeled using finite element simulations. These results demonstrate that the morphology and composition of individual bimetallic nanocrystals can be engineered electrochemically. PMID:26273983

  6. Negative electrode composition

    DOEpatents

    Kaun, Thomas D.; Chilenskas, Albert A.

    1982-01-01

    A secondary electrochemical cell and a negative electrode composition for use therewith comprising a positive electrode containing an active material of a chalcogen or a transiton metal chalcogenide, a negative electrode containing a lithium-aluminum alloy and an amount of a ternary alloy sufficient to provide at least about 5 percent overcharge capacity relative to a negative electrode solely of the lithium-aluminum alloy, the ternary alloy comprising lithium, aluminum, and iron or cobalt, and an electrolyte containing lithium ions in contact with both of the positive and the negative electrodes. The ternary alloy is present in the electrode in the range of from about 5 percent to about 50 percent by weight of the electrode composition and may include lithium-aluminum-nickel alloy in combination with either the ternary iron or cobalt alloys. A plurality of series connected cells having overcharge capacity can be equalized on the discharge side without expensive electrical equipment.

  7. Indium-free organic thin-film solar cells using a plasmonic electrode

    NASA Astrophysics Data System (ADS)

    Takatori, Kentaro; Nishino, Takayuki; Okamoto, Takayuki; Takei, Hiroyuki; Ishibashi, Koji; Micheletto, Ruggero

    2016-05-01

    We propose a new kind of organic solar cell (OSC) that substitutes the standard indium tin oxide (ITO) electrode with a silver layer with randomly arranged circular nanoholes (plasmonic electrode). The quasi-random structure in the silver layer efficiently converts wideband incident light into surface plasmon polaritons propagating along the surface of the silver film. In this way, the converted surface plasmon polaritons enhance light absorption in the active layer. We describe in detail the fabrication process we used and we give a thorough report of the resulting optical characteristics and performances. Although the transmittance of the plasmonic electrode is approximately one-third of that of the ITO electrodes, the power conversion efficiency of the OSCs with our plasmonic electrode is comparable to that of conventional inverted solar cells using ITO electrodes. Moreover, the obtained incident photon to current efficiency was better than that of the inverted solar cells in the wavelength regions around 400 nm and over 620 nm.

  8. Capillary flow of amorphous metal for high performance electrode.

    PubMed

    Kim, Se Yun; Kim, Suk Jun; Jee, Sang Soo; Park, Jin Man; Park, Keum Hwan; Park, Sung Chan; Cho, Eun Ae; Lee, Jun Ho; Song, In Yong; Lee, Sang Mock; Han, In Taek; Lim, Ka Ram; Kim, Won Tae; Park, Ju Cheol; Eckert, Jürgen; Kim, Do Hyang; Lee, Eun-Sung

    2013-01-01

    Metallic glass (MG) assists electrical contact of screen-printed silver electrodes and leads to comparable electrode performance to that of electroplated electrodes. For high electrode performance, MG needs to be infiltrated into nanometer-scale cavities between Ag particles and reacts with them. Here, we show that the MG in the supercooled state can fill the gap between Ag particles within a remarkably short time due to capillary effect. The flow behavior of the MG is revealed by computational fluid dynamics and density funtional theory simulation. Also, we suggest the formation mechanism of the Ag electrodes, and demonstrate the criteria of MG for higher electrode performance. Consequently, when Al85Ni5Y8Co2 MG is added in the Ag electrodes, cell efficiency is enhanced up to 20.30% which is the highest efficiency reported so far for screen-printed interdigitated back contact solar cells. These results show the possibility for the replacement of electroplating process to screen-printing process.

  9. Silver stain for electron microscopy

    NASA Technical Reports Server (NTRS)

    Corbett, R. L.

    1972-01-01

    Ammoniacal silver stain used for light microscopy was adapted advantageously for use with very thin biological sections required for electron microscopy. Silver stain can be performed in short time, has more contrast, and is especially useful for low power electron microscopy.

  10. Corrosion protection for silver reflectors

    DOEpatents

    Arendt, Paul N.; Scott, Marion L.

    1991-12-31

    A method of protecting silver reflectors from damage caused by contact with gaseous substances which are often present in the atmosphere and a silver reflector which is so protected. The inventive method comprises at least partially coating a reflector with a metal oxide such as aluminum oxide to a thickness of 15 .ANG. or less.

  11. Silver against Pseudomonas aeruginosa biofilms.

    PubMed

    Bjarnsholt, Thomas; Kirketerp-Møller, Klaus; Kristiansen, Søren; Phipps, Richard; Nielsen, Anne Kirstine; Jensen, Peter Østrup; Høiby, Niels; Givskov, Michael

    2007-08-01

    Silver has been recognized for its antimicrobial properties for centuries. Most studies on the antibacterial efficacy of silver, with particular emphasis on wound healing, have been performed on planktonic bacteria. Our recent studies, however, strongly suggest that colonization of wounds involves bacteria in both the planktonic and biofilm modes of growth. The action of silver on mature in vitro biofilms of Pseudomonas aeruginosa, a primary pathogen of chronic infected wounds, was investigated. The results show that silver is very effective against mature biofilms of P. aeruginosa, but that the silver concentration is important. A concentration of 5-10 mug/mL silver sulfadiazine eradicated the biofilm whereas a lower concentration (1 mug/mL) had no effect. The bactericidal concentration of silver required to eradicate the bacterial biofilm was 10-100 times higher than that used to eradicate planktonic bacteria. These observations strongly indicate that the concentration of silver in currently available wound dressings is much too low for treatment of chronic biofilm wounds. It is suggested that clinicians and manufacturers of the said wound dressings consider whether they are treating wounds primarily colonized either by biofilm-forming or planktonic bacteria.

  12. High Pressure Electrochemistry: Application to silver halides

    NASA Astrophysics Data System (ADS)

    Havens, K.; Kavner, A.

    2007-12-01

    Electron and ion charge transfer processes help govern electrical conductivity and diffusive mass and heat transport properties in deep Earth minerals. In an attempt to understand how pressure influences charge transfer behavior, the halide silver bromide (AgBr) was studied under the influence of an electric potential difference applied across two electrodes in a diamond anvil cell. This study follows our previous work on AgI, which was found to dissociate to molecular iodine and silver metal due to pressure and voltage influences. We performed two sets of experiments on AgBr at high pressure in a diamond anvil cell: electrochemical dissociation and electrical resistance measurements. In our study, we were able to electrochemically dissociate AgBr at pressures of 0.25-1.6 GPa by applying a voltage across the electrodes in the diamond cell sample chamber. Ag metal grew visibly on the negatively-charged electrode when voltages varying from 0.1 V to 5 V were applied. Additionally, a dark blue color appeared in low pressure areas of the diamond cell and grew darker from both voltage application and light exposure, indicating photochemical effects. We found that the reaction area and growth rate of both metal and dark blue color strongly increased as voltage increased, but tended to decrease with greater pressure. The resistance across the cell was observed to be influenced by both pressure and light exposure. As the AgBr sample was exposed to visible light, the resistance dropped instantaneously, and after the light was turned off, the resistance increased on a timescale of 10's of seconds to minutes. Notably, at higher pressures, the AgBr showed less photosensitivity. Exploration of these metal halide systems has many potential applications. First, these experiments explore the pressure-dependence of photochemical and photovoltaic processes, and may spur development of pressure-tuned microscale electronic devices. Second, these experimental results can be used to

  13. Novel Conductive Carbon Black and Polydimethlysiloxane ECG Electrode: A Comparison with Commercial Electrodes in Fresh, Chlorinated, and Salt Water.

    PubMed

    Noh, Yeonsik; Bales, Justin R; Reyes, Bersain A; Molignano, Jennifer; Clement, Amanda L; Pins, George D; Florian, John P; Chon, Ki H

    2016-08-01

    In this study, we evaluated the performance of two novel conductive carbon black (CB) and polydimethlysiloxane (PDMS) bio-potential electrodes, with and without an integrated flexible copper mesh, against commercially available electrodes (Polar(®) textile, Silver-coated textile, and carbon rubber). The electrodes were tested in three types of water (fresh/unfiltered, chlorinated, and salt water). Our testing revealed that our CB/PDMS electrode with integrated copper mesh provided a high-fidelity ECG signal morphologies without any amplitude degradation in all of the types of water tested (N = 10). The non-meshed CB/PDMS electrodes were also subjected to a long-term durability test by the US Navy SCUBA divers during which the electrodes maintained ECG signal quality for a 6 h period of continuous use. The results of a material degradation analysis revealed the CB/PDMS composite material does not exhibit significant changes in physical integrity after prolonged exposure to the test conditions. The newly developed meshed CB/PDMS electrodes have the potential to be used in a wide variety of both dry and wet environments including the challenge of obtaining ECG signals in salt water environments.

  14. Novel Conductive Carbon Black and Polydimethlysiloxane ECG Electrode: A Comparison with Commercial Electrodes in Fresh, Chlorinated, and Salt Water.

    PubMed

    Noh, Yeonsik; Bales, Justin R; Reyes, Bersain A; Molignano, Jennifer; Clement, Amanda L; Pins, George D; Florian, John P; Chon, Ki H

    2016-08-01

    In this study, we evaluated the performance of two novel conductive carbon black (CB) and polydimethlysiloxane (PDMS) bio-potential electrodes, with and without an integrated flexible copper mesh, against commercially available electrodes (Polar(®) textile, Silver-coated textile, and carbon rubber). The electrodes were tested in three types of water (fresh/unfiltered, chlorinated, and salt water). Our testing revealed that our CB/PDMS electrode with integrated copper mesh provided a high-fidelity ECG signal morphologies without any amplitude degradation in all of the types of water tested (N = 10). The non-meshed CB/PDMS electrodes were also subjected to a long-term durability test by the US Navy SCUBA divers during which the electrodes maintained ECG signal quality for a 6 h period of continuous use. The results of a material degradation analysis revealed the CB/PDMS composite material does not exhibit significant changes in physical integrity after prolonged exposure to the test conditions. The newly developed meshed CB/PDMS electrodes have the potential to be used in a wide variety of both dry and wet environments including the challenge of obtaining ECG signals in salt water environments. PMID:26769718

  15. Shape- and size-selective electrochemical synthesis of dispersed silver(I) oxide colloids.

    PubMed

    Murray, B J; Li, Q; Newberg, J T; Menke, E J; Hemminger, J C; Penner, R M

    2005-11-01

    Silver(I) oxide (Ag2O) micro- and nanoparticles were electrochemically synthesized by anodizing a sacrificial silver wire in a basic aqueous sulfate solution. Ag2O particles were released from the silver electrode surface during synthesis producing a visible sol "stream". The composition of these particles was established using selected area electron diffraction, X-ray diffraction, and X-ray photoelectron spectroscopy. The shape of Ag2O crystallites could be adjusted using the potential of the silver wire generator electrode. The generation of a dispersed Ag2O sol and the observed shape selectivity are both explained by a two-step mechanism involving the anodic dissolution of silver metal, Ag0 --> Ag+(aq) + 1e-, followed by the precipitation of Ag2O particles, 2Ag+ + 2OH- --> Ag2O(s) + H2O. Within 100 mV of the voltage threshold for particle growth, cubic particles with a depression in each face ("hopper crystals") were produced. The application of more positive voltages resulted in the generation of 8-fold symmetric "flower"-shaped particles formed as a consequence of fast growth in the <111> crystallographic direction. The diameter of flower particles was adjustable from 250 nm to 1.8 microm using the growth duration at constant potential.

  16. Reversible migration of silver on memorized pathways in Ag-Ge40S60 films

    NASA Astrophysics Data System (ADS)

    Orava, J.; Kozicki, M. N.; Yannopoulos, S. N.; Greer, A. L.

    2015-07-01

    Reversible and reproducible formation and dissolution of silver conductive filaments are studied in Ag-photodoped thin-film Ge40S60 subjected to electric fields. A tip-planar geometry is employed, where a conductive-atomic-force microscopy tip is the tip electrode and a silver patch is the planar electrode. We highlight an inherent "memory" effect in the amorphous chalcogenide solid-state electrolyte, in which particular silver-ion migration pathways are preserved "memorized" during writing and erasing cycles. The "memorized" pathways reflect structural changes in the photodoped chalcogenide film. Structural changes due to silver photodoping, and electrically-induced structural changes arising from silver migration, are elucidated using Raman spectroscopy. Conductive filament formation, dissolution, and electron (reduction) efficiency in a lateral device geometry are related to operation of the nano-ionic Programmable Metallization Cell memory and to newly emerging chalcogenide-based lateral geometry MEMS technologies. The methods in this work can also be used for qualitative multi-parameter sampling of metal/amorphous-chalcogenide combinations, characterizing the growth/dissolution rates, retention and endurance of fractal conductive filaments, with the aim of optimizing devices.

  17. Synthesis and application of graphene-silver nanowires composite for ammonia gas sensing

    NASA Astrophysics Data System (ADS)

    Tran, Quang Trung; Hoa Huynh, Tran My; Tong, Duc Tai; Tam Tran, Van; Dinh Nguyen, Nang

    2013-12-01

    Graphene, consisting of a single carbon layer in a two-dimensional (2D) lattice, has been a promising material for application to nanoelectrical devices in recent years. In this study we report the development of a useful ammonia (NH3) gas sensor based on graphene-silver nanowires ‘composite’ with planar electrode structure. The basic strategy involves three steps: (i) preparation of graphene oxide (GO) by modified Hummers method; (ii) synthesis of silver nanowires by polyol method; and (iii) preparation of graphene and silver nanowires on two electrodes using spin and spray-coating of precursor solutions, respectively. Exposure of this sensor to NH3 induces a reversible resistance change at room temperature that is as large as ΔR/R0 ˜ 28% and this sensitivity is eight times larger than the sensitivity of the ‘intrinsic’ graphene based NH3 gas sensor (ΔR/R0 ˜ 3,5%). Their responses and the recovery times go down to ˜200 and ˜60 s, respectively. Because graphene synthesized by chemical methods has many defects and small sheets, it cannot be perfectly used for gas sensor or for nanoelectrical devices. The silver nanowires are applied to play the role of small bridges connecting many graphene islands together to improve electrical properties of graphene/silver nanowires composite and result in higher NH3 gas sensitivity.

  18. Rethinking Schools and the Power of Silver

    ERIC Educational Resources Information Center

    Sleeter, Christine

    2011-01-01

    This 25th anniversary of "Rethinking Schools" can be thought of as its silver anniversary. Silver itself must be considered through contrasting lenses. On the one hand, as lessons in "Rethinking Globalization" teach, silver and gold were the basis of Europe's horrendous exploitation of Latin America. On the other hand, silver is often associated…

  19. "Bottom-up" transparent electrodes.

    PubMed

    Morag, Ahiud; Jelinek, Raz

    2016-11-15

    Transparent electrodes (TEs) have attracted significant scientific, technological, and commercial interest in recent years due to the broad and growing use of such devices in electro-optics, consumer products (touch-screens for example), solar cells, and others. Currently, almost all commercial TEs are fabricated through "top-down" approaches (primarily lithography-based techniques), with indium tin oxide (ITO) as the most common material employed. Several problems are encountered, however, in this field, including the cost and complexity of TE production using top-down technologies, the limited structural flexibility, high-cost of indium, and brittle nature and low transparency in the far-IR spectral region of ITO. Alternative routes based upon bottom-up processes, have recently emerged as viable alternatives for production of TEs. Bottom up technologies are based upon self-assembly of building blocks - atoms, molecules, or nanoparticles - generating thin patterned films that exhibit both electrical conductivity and optical transparency. In this Feature Article we discuss the recent progress in this active and exciting field, including bottom-up TE systems produced from carbon materials (carbon nanotubes, graphene, graphene-oxide), silver, gold, and other metals. The current hurdles encountered for broader use of bottom-up strategies along with their significant potential are analyzed. PMID:27545510

  20. "Bottom-up" transparent electrodes.

    PubMed

    Morag, Ahiud; Jelinek, Raz

    2016-11-15

    Transparent electrodes (TEs) have attracted significant scientific, technological, and commercial interest in recent years due to the broad and growing use of such devices in electro-optics, consumer products (touch-screens for example), solar cells, and others. Currently, almost all commercial TEs are fabricated through "top-down" approaches (primarily lithography-based techniques), with indium tin oxide (ITO) as the most common material employed. Several problems are encountered, however, in this field, including the cost and complexity of TE production using top-down technologies, the limited structural flexibility, high-cost of indium, and brittle nature and low transparency in the far-IR spectral region of ITO. Alternative routes based upon bottom-up processes, have recently emerged as viable alternatives for production of TEs. Bottom up technologies are based upon self-assembly of building blocks - atoms, molecules, or nanoparticles - generating thin patterned films that exhibit both electrical conductivity and optical transparency. In this Feature Article we discuss the recent progress in this active and exciting field, including bottom-up TE systems produced from carbon materials (carbon nanotubes, graphene, graphene-oxide), silver, gold, and other metals. The current hurdles encountered for broader use of bottom-up strategies along with their significant potential are analyzed.

  1. Contribution of specifically adsorbed ions, water, and impurities to the surface enhanced Raman spectroscopy (SERS) of Ag electrodes

    NASA Astrophysics Data System (ADS)

    Pettinger, Bruno; Philpott, Michael R.; Gordon, Joseph G., II

    1981-01-01

    Surface enhanced Raman scattering (SERS) has been observed from silver electrodes for water (H2O and D2O) in the frequency region of the librational, bending, and stretching modes. Simultaneously, SERS has been observed for halide ions and some organic impurities. The appearance of SERS from water and halide ions under the circumstances of the experiment is attributed to the formation of surface complexes involving silver adatoms, halide ions, and water molecules.

  2. Thermal stability of PLD grown silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Shokeen, Poonam; Jain, Amit; Kapoor, Avinashi

    2016-05-01

    Present work discusses the stability of silver nanoparticles at different annealing temperatures. Air muffle furnace annealing is performed to study the thermal stability of pulsed laser deposited silver nanoparticles. Silver reacts with atmospheric oxygen to form silver oxide at annealing temperatures below 473K and thermal decomposition of silver oxide takes place at temperatures above 473K. Oxide formation results in core shrinkage of silver, which in turn affects the surface plasmon resonance of silver nanoparticles. With increase in annealing temperature, the surface plasmon effect of nanoparticles starts to fade. SEM, XRD and UV-vis spectroscopy have been performed to analysis various structural and optical properties.

  3. A Silver DNAzyme.

    PubMed

    Saran, Runjhun; Liu, Juewen

    2016-04-01

    Silver is a very common heavy metal, and its detection is of significant analytical importance. DNAzymes are DNA-based catalysts; they typically recruit divalent and trivalent metal ions for catalysis. Herein, we report a silver-specific RNA-cleaving DNAzyme named Ag10c obtained after six rounds of in vitro selection. Ag10c displays a catalytic rate of 0.41 min(-1) with 10 μM Ag(+) at pH 7.5 with 200 mM NaNO3, while its activity is completely inhibited with the same concentration of NaCl. Ag10c is highly specific for Ag(+) among all the tested metals. A catalytic beacon biosensor is designed by labeling a fluorophore and a quencher on the DNAzyme. Fluorescence enhancement is observed in the presence of Ag(+) with a detection limit of 24.9 nM Ag(+). The sensor shows a similar analytical performance in Lake Huron water. This is the first monovalent transition metal dependent RNA-cleaving DNAzyme. Apart from its biosensor application, this study strengthens the idea of exploring beyond the traditional understanding of multivalent ion dependent DNAzyme catalysis. PMID:26977895

  4. A Silver DNAzyme.

    PubMed

    Saran, Runjhun; Liu, Juewen

    2016-04-01

    Silver is a very common heavy metal, and its detection is of significant analytical importance. DNAzymes are DNA-based catalysts; they typically recruit divalent and trivalent metal ions for catalysis. Herein, we report a silver-specific RNA-cleaving DNAzyme named Ag10c obtained after six rounds of in vitro selection. Ag10c displays a catalytic rate of 0.41 min(-1) with 10 μM Ag(+) at pH 7.5 with 200 mM NaNO3, while its activity is completely inhibited with the same concentration of NaCl. Ag10c is highly specific for Ag(+) among all the tested metals. A catalytic beacon biosensor is designed by labeling a fluorophore and a quencher on the DNAzyme. Fluorescence enhancement is observed in the presence of Ag(+) with a detection limit of 24.9 nM Ag(+). The sensor shows a similar analytical performance in Lake Huron water. This is the first monovalent transition metal dependent RNA-cleaving DNAzyme. Apart from its biosensor application, this study strengthens the idea of exploring beyond the traditional understanding of multivalent ion dependent DNAzyme catalysis.

  5. Retiring the Silver Bullet

    SciTech Connect

    Lasure, Linda L.

    2006-01-01

    Over the past few decades, advances in biology and electronics have resulted in an enormous increase in the screening rate of new compounds and in the capacity to synthesize vast numbers of new compounds. The understanding of disease has greatly improved. At the same time, the number of targets (or diseases) for the silver bullets has also increased. Yet, the belief that we have to screen enormous numbers of compounds to find the next new drug continues. Today, disease is understood to be a complex interaction of many systems. This ought to cause us to change our paradigm, but it has not. The fundamental reason for the apparent failure of our drug discovery and development research is that we are operating under the constraints of an out-of-date paradigm. The silver-bullet paradigm has always been a myth. Now is the time to debunk the myth and change the paradigm. Our other option is to continue on as we are and accept that the United States will become obsolete on the playing field of drug discovery.

  6. Process for making silver metal filaments

    DOEpatents

    Bamberger, Carlos E.

    1997-01-01

    A process for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles.

  7. Process for making silver metal filaments

    SciTech Connect

    Bamberger, C.E.

    1997-05-06

    A process is disclosed for making silver metal particles from silver salt particles having the same morphology. Precursor silver salt particles selected from the group consisting of silver acetate and silver sulfide having a selected morphology are contained in a reactor vessel having means for supporting the particles in an air suspension to prevent the agglomeration of the particles. Air is flowed through the reactor vessel at a flow rate sufficient to suspend the particles in the reactor vessel. The suspended precursor silver salt particles are heated to a processing temperature and at a heating rate below which the physical deterioration of the suspended precursor silver salt particles takes place. The suspended precursor silver salt particles are maintained at the processing temperature for a period of time sufficient to convert the particles into silver metal particles having the same morphology as the precursor silver salt particles. 1 fig.

  8. Electrodic voltages in the presence of dissolved sulfide: Implications for monitoring natural microbial activity

    SciTech Connect

    Slater, L.; Ntarlagiannis, D.; Yee, N.; O'Brien, M.; Zhang, C.; Williams, K. H.

    2008-10-01

    There is growing interest in the development of new monitoring strategies for obtaining spatially extensive data diagnostic of microbial processes occurring in the earth. Open-circuit potentials arising from variable redox conditions in the fluid local-to-electrode surfaces (electrodic potentials) were recorded for a pair of silver-silver chloride electrodes in a column experiment, whereby a natural wetland soil containing a known community of sulfate reducers was continuously fed with a sulfate-rich nutrient medium. Measurements were made between five electrodes equally spaced along the column and a reference electrode placed on the column inflow. The presence of a sulfate reducing microbial population, coupled with observations of decreasing sulfate levels, formation of black precipitate (likely iron sulfide),elevated solid phase sulfide, and a characteristic sulfurous smell, suggest microbial-driven sulfate reduction (sulfide generation) in our column. Based on the known sensitivity of a silver electrode to dissolved sulfide concentration, we interpret the electrodic potentials approaching 700 mV recorded in this experiment as an indicator of the bisulfide (HS-) concentration gradients in the column. The measurement of the spatial and temporal variation in these electrodic potentials provides a simple and rapid method for monitoring patterns of relative HS- concentration that are indicative of the activity of sulfate-reducing bacteria. Our measurements have implications both for the autonomous monitoring of anaerobic microbial processes in the subsurface and the performance of self-potential electrodes, where it is critical to isolate, and perhaps quantify, electrochemical interfaces contributing to observed potentials.

  9. Bifunctional alkaline oxygen electrodes

    NASA Technical Reports Server (NTRS)

    Swette, L.; Kackley, N.; Mccatty, S. A.

    1991-01-01

    The authors describe the identification and testing of electrocatalysts and supports for the positive electrode of moderate-temperature, single-unit, rechargeable alkaline fuel cells. Recent work on Na(x)Pt3O4, a potential bifunctional catalyst, is described, as well as the application of novel approaches to the development of more efficient bifunctional electrode structures. The three dual-character electrodes considered here showed similar superior performance; the Pt/RhO2 and Rh/RhO2 electrodes showed slightly better performance than the Pt/IrO2 electrode. It is concluded that Na(x)Pt3O4 continues to be a promising bifunctional oxygen electrode catalyst but requires further investigation and development.

  10. Uncharged positive electrode composition

    DOEpatents

    Kaun, Thomas D.; Vissers, Donald R.; Shimotake, Hiroshi

    1977-03-08

    An uncharged positive-electrode composition contains particulate lithium sulfide, another alkali metal or alkaline earth metal compound other than sulfide, e.g., lithium carbide, and a transition metal powder. The composition along with a binder, such as electrolytic salt or a thermosetting resin is applied onto an electrically conductive substrate to form a plaque. The plaque is assembled as a positive electrode within an electrochemical cell opposite to a negative electrode containing a material such as aluminum or silicon for alloying with lithium. During charging, lithium alloy is formed within the negative electrode and transition metal sulfide such as iron sulfide is produced within the positive electrode. Excess negative electrode capacity over that from the transition metal sulfide is provided due to the electrochemical reaction of the other than sulfide alkali metal or alkaline earth metal compound.

  11. Nanoscopic electrode molecular probes

    DOEpatents

    Krstic, Predrag S.; Meunier, Vincent

    2012-05-22

    The present invention relates to a method and apparatus for enhancing the electron transport property measurements of a molecule when the molecule is placed between chemically functionalized carbon-based nanoscopic electrodes to which a suitable voltage bias is applied. The invention includes selecting a dopant atom for the nanoscopic electrodes, the dopant atoms being chemically similar to atoms present in the molecule, and functionalizing the outer surface and terminations of the electrodes with the dopant atoms.

  12. Pocket ECG electrode

    NASA Technical Reports Server (NTRS)

    Lund, Gordon F. (Inventor)

    1982-01-01

    A low-noise electrode suited for sensing electrocardiograms when chronically and subcutaneously implanted in a free-ranging subject. The electrode comprises a pocket-shaped electrically conductive member with a single entrance adapted to receive body fluids. The exterior of the member and the entrance region is coated with electrical insulation so that the only electrolyte/electrode interface is within the member remote from artifact-generating tissue. Cloth straps are bonded to the member to permit the electrode to be sutured to tissue and to provide electrical lead flexure relief.

  13. Pocket ECG electrode

    NASA Technical Reports Server (NTRS)

    Lund, G. F. (Inventor)

    1980-01-01

    A low noise electrode suited for sensing electrocardiograms when chronically and subcutaneously implanted in a free ranging subject is described. The electrode comprises a pocket shaped electrically conductive member with a single entrance adapted to receive body fluids. The exterior of the member and the entrance region is coated with electrical insulation so that the only electrolyte/electrode interface is within the member, remote from artifact-generating tissue. Cloth straps are bonded to the member to permit the electrode to be sutured to tissue and to provide electrical lead flexure relief.

  14. Polyacrylate microspheres composite for all-solid-state reference electrodes.

    PubMed

    Kisiel, Anna; Donten, Mikołaj; Mieczkowski, Józef; Rius-Ruiz, F Xavier; Maksymiuk, Krzysztof; Michalska, Agata

    2010-09-01

    A novel concept is proposed for the encapsulation of components within polyacrylate microspheres, prior to their incorporation into a membrane phase. Thus finer and better controlled dispersion of heterogeneous membrane components can be achieved. This concept was verified by using a poly(n-butyl acrylate) membrane-based reference electrode as an example. In this example the proper dispersion of solid constituents of the heterogeneous membrane and prevention of their leakage are both of primary importance. Potassium chloride-loaded poly(n-butyl acrylate) microspheres were prepared and then left in contact with silver nitrate to convert some of the KCl into AgCl. The material obtained was introduced into a poly(n-butyl acrylate) membrane. The reference electrode membranes obtained in this way were characterized with much more stable potential (both in different electrolytes and over time) compared with electrodes prepared by the direct introduction of KCl and AgCl to the membrane. PMID:20652191

  15. Ni-BaTiO3-Based Base-Metal Electrode (BME) Ceramic Capacitors for Space Applications

    NASA Technical Reports Server (NTRS)

    Liu, Donhang; Fetter, Lula; Meinhold, Bruce

    2015-01-01

    A multi-layer ceramic capacitor (MLCC) is a high-temperature (1350C typical) co-fired ceramic monolithic that is composed of many layers of alternately stacked oxide-based dielectric and internal metal electrodes. To make the dielectric layers insulating and the metal electrode layers conducting, only highly oxidation-resistant precious metals, such as platinum, palladium, and silver, can be used for the co-firing of insulating MLCCs in a regular air atmosphere. MLCCs made with precious metals as internal electrodes and terminations are called precious-metal electrode (PME) capacitors. Currently, all military and space-level applications only address the use of PME capacitors.

  16. Silver Complexes of Dihalogen Molecules.

    PubMed

    Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

    2016-08-01

    The perfluorohexane-soluble and donor-free silver compound Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) prepared using a facile novel route has unprecedented capabilities to form unusual and weakly bound complexes. Here, we report on the three dihalogen-silver complexes Ag(Cl2 )A, Ag(Br2 )A, and Ag(I2 )A derived from the soluble silver compound Ag(A) (characterized by single-crystal/powder XRD, Raman spectra, and quantum-mechanical calculations). PMID:27404568

  17. MOD silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

    Vest, G. M.; Vest, R. W.

    1985-01-01

    The feasibility of utilizing metallo-organic decomposition (MOD) silver inks were investigated for front contact metallization of solar cells. Generic synthesis procedures were developed for all metallo-organic compounds investigated. Silver neodecanoate was found to be the most suitable silver metallo-organic compound for use in thick film inks, but the quality of the inks was found to be highly dependent on its purity. Although neither the process nor inks were completely optimized for solar cell front contact metallization, they show great promise for this application.

  18. Interesting electrochemical properties of novel three-dimensional Ag3PO4 tetrapods as a new super capacitor electrode material

    NASA Astrophysics Data System (ADS)

    Li, Shouguang; Teng, Fei; Chen, Mindong; Li, Na; Hua, Xia; Wang, Kai; Li, Min

    2014-05-01

    The novel three-dimensional (3D) silver phosphate tetrapods (TA) are synthesized and employed as a super capacitor electrode material. The electrochemical properties are investigated by cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS). It is interesting that compared with irregular silver phosphate particles (IA), TA shows a higher capacitance (250 vs. 160 F g-1), and a higher coulombic efficiency (80% vs. 74%), which is mainly ascribed to the 3D microstructure and its high conductivity. To the best of our knowledge, this is the first report on silver phosphate as a super capacitor material.

  19. Influence of surface properties on the structure of granular silver films and excitation of localized plasmons

    NASA Astrophysics Data System (ADS)

    Shcherbinin, D. P.; Konshina, E. A.; Polischuk, V. A.

    2016-04-01

    Granular silver films deposited on a thin insulating film of amorphous hydrogenated carbon ( a-C:H) and transparent conducting electrode (polycrystalline indium tin oxide (ITO) layer) have been investigated by spectroscopy and microscopy methods. The extinction spectra of silver films on the surface of these materials are found to be significantly different. An annealing of silver films causes a blue shift of the peak of plasmon resonance band in the spectrum of silver nanoparticles: by 16 nm on the a-C:H surface and by 94 nm on the ITO surface. Silver films on the surface of a-C:H films are characterized by a narrower band in the extinction spectrum, which is peaked at 446 nm. The changes observed in the optical density of Ag films are related to the change in size and area of nanoparticles. The results of spectral studies of Ag films are in agreement with the data on the nanostructure obtained by scanning electron microscopy and statistical image processing. The spectra of granular silver films are shown to correlate well with the nanoparticle distribution function over the film area.

  20. Size effect of silver nanoclusters on their catalytic activity for oxygen electro-reduction

    NASA Astrophysics Data System (ADS)

    Lu, Yizhong; Chen, Wei

    2012-01-01

    Two different sized silver nanoclusters are prepared by two different synthetic routs. First, a small nanocluster (NC) which is 0.7 nm in diameter was synthesized by using meso-2, 3-dimercapto-succinic acid (DMSA) as a capping ligand, and second a larger nanoparticle (NP) which is 3.3 nm in diameter was prepared by chemical reduction and coated with DMSA. The as-prepared silver nanoclusters or nanoparticles are then loaded onto a glassy carbon electrode and the size effect on their electrocatalytic activity toward oxygen reduction reaction (ORR) is investigated with electrochemical techniques in alkaline electrolyte. The cyclic voltammetric (CV) studies show that the onset potential of ORR on 0.7 nm silver nanoclusters is 150 mV more positive than that from 3.3 nm silver nanoparticles. And compared to the larger nanoparticles, five times higher current density of ORR at -0.80 V is obtained from the 0.7 nm silver nanoclusters. These CV results indicate that the smaller Ag nanoclusters exhibit higher catalytic performance for ORR. Rotating disk voltammetric studies show ORR on both DMSA monolayer-protected silver clusters is dominated first by a two-electron transfer pathway to produce H2O2 and then peroxide is reduced by 2 more electrons to produce water.

  1. Performance and electrochemical behavior of fluidized bed electrodes

    SciTech Connect

    Huh, T.

    1985-01-01

    The fluidized bed electrode was studied to characterize its behavior and evaluate its possible application to the electrowinning of precious metals and to the energy storage systems. Its performance and electrochemical behavior were analyzed in terms of various operating parameters. The first part of the study is concerned mainly with the overall performance of a fluidized-bed electrode for silver recovery from aqueous cyanide solution. The effects of applied current density, bed expansion, and electrode materials were considered, and its was found that the performance is free of operating problems and is superior to the Azadra-type cell, which is commonly used for precious metal recovery. The second part is concerned with the internal behavior of the fluidized bed electrode. The particle and electrolyte potentials and overpotentials in fluidized bed electrodes of two different types have been measured and analyzed by means of the probability density distribution and the power spectral density distribution. The resistance of such electrodes are also measured. The potential transients are observed to depend on current, bed expansion, and position in the bed (for copper particles) and each potential can be regarded as a time averaged value onto which two kinds of noise, low-frequency flicker noise and white noise, are added.

  2. Antimicrobial effects of silver zeolite, silver zirconium phosphate silicate and silver zirconium phosphate against oral microorganisms

    PubMed Central

    Saengmee-anupharb, Sirikamon; Srikhirin, Toemsak; Thaweboon, Boonyanit; Thaweboon, Sroisiri; Amornsakchai, Taweechai; Dechkunakorn, Surachai; Suddhasthira, Theeralaksna; Kamaguchi, Arihide

    2013-01-01

    Objective To evaluate the antimicrobial activities of silver inorganic materials, including silver zeolite (AgZ), silver zirconium phosphate silicate (AgZrPSi) and silver zirconium phosphate (AgZrP), against oral microorganisms. In line with this objective, the morphology and structure of each type of silver based powders were also investigated. Methods The antimicrobial activities of AgZ, AgZrPSi and AgZrP were tested against Streptococcus mutans, Lactobacillus casei, Candida albicans and Staphylococcus aureus using disk diffusion assay as a screening test. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were determined using the modified membrane method. Scanning electron microscope and X-ray diffraction were used to investigate the morphology and structure of these silver materials. Results All forms of silver inorganic materials could inhibit the growth of all test microorganisms. The MIC of AgZ, AgZrPSi and AgZrP was 10.0 g/L whereas MLC ranged between 10.0–60.0 g/L. In terms of morphology and structure, AgZrPSi and AgZrP had smaller sized particles (1.5–3.0 µm) and more uniformly shaped than AgZ. Conclusions Silver inorganic materials in the form of AgZ, AgZrPSi and AgZrP had antimicrobial effects against all test oral microorganisms and those activities may be influenced by the crystal structure of carriers. These results suggest that these silver materials may be useful metals applied to oral hygiene products to provide antimicrobial activity against oral infection. PMID:23570016

  3. Local heat/mass transfer and pressure drop in a two-pass rib-roughened channel for turbine airfoil cooling

    NASA Technical Reports Server (NTRS)

    Han, J. C.; Chandra, P. R.

    1987-01-01

    The heat transfer characteristics of turbulent air flow in a multipass channel were studied via the naphthalene sublimation technique. The naphthalene-coated test section, consisting of two straight, square channels joined by a 180 deg turn, resembled the internal cooling passages of gas turbine airfoils. The top and bottom surfaces of the test channel were roughened by rib turbulators. The rib height-to-hydraulic diameter ratio (e/D) were 0.063 and 0.094, and the rib pitch-to-height ratio (P/e) were 10 and 20. The local heat/mass transfer coefficients on the roughened top wall and on the smooth divider and side walls of the test channel were determined for three Reynolds numbers of 15, 30, and 60, thousand, and for three angles of attack (alpha) of 90, 60, and 45 deg. Results showed that the local Sherwood numbers on the ribbed walls were 1.5 to 6.5 times those for a fully developed flow in a smooth square duct. The average ribbed-wall Sherwood numbers were 2.5 to 3.5 times higher than the fully developed values, depending on the rib angle of attack and the Reynolds number. The results also indicated that, before the turn, the heat/mass transfer coefficients in the cases of alpha = 60 and 45 deg were higher than those in the case of alpha=90 deg. However, after the turn, the heat/mass transfer coefficients in the oblique-rib cases were lower than those in the transverse rib case. Correlations for the average Sherwood number ratios for individual channel surfaces and for the overall Sherwood number ratios are reported. Correlations for the fully developed friction factors and for the loss coefficients are also provided.

  4. Determination of nicotine by surface-enhanced Raman scattering (SERS)

    SciTech Connect

    Barber, T.E.; List, M.S.; Haas, J.W. III; Wachter, E.A. )

    1994-11-01

    The analytical application of surface-enhanced Raman spectroscopy (SERS) to the determination of nicotine is demonstrated. A simple spectroelectrochemical method using a copper or silver electrode as the SERS substrate has been developed, consisting of three steps: polishing a working electrode to a mirror finish; roughening the electrode in an electrolyte solution; and, finally, depositing the nicotine analyte onto the roughened electrode after immersion in a sample solution. During the reduction cycle, a large enhancement in nicotine Raman scattering is observed at the electrode surface. The intensity of the SERS signal on a silver electrode is linear with concentration from 10 to 900 ppb, with an estimated detection limit of 7 ppb. The total analysis time per sample is approximately five minutes. This procedure has been used to analyze the extract from a cigarette side-stream smoke sample (environmental tobacco smoke); the SERS results agree well with those of conventional gas chromatographic analysis.

  5. Silver Nafion for Thermogalvanic Applications

    NASA Astrophysics Data System (ADS)

    Chang, William; Popere, Bhooshan; Evans, Chris; Russ, Boris; Segalman, Rachel

    2015-03-01

    Thermogalvanics convert a temperature gradient, typically from waste heat, into electrical power using a reversible electrochemical reaction. The conversion efficiency in thermogalvanics, like with thermoelectrics, are governed by the Seebeck coefficient, the carrier conductivity and the thermal conductivity of the material. We demonstrate that the material systems silver Nafion and silver poly-styrenesulfonate are air-stable, water processable materials that demonstrate extremely high Seebeck coefficients and moderate carrier conductivities. These power factors, when coupled with the low thermal conductivities inherent in polymers, results in materials with excellent thermogalvanic figure of merits. We show the dependence of these three material properties to material composition and processing. In this talk, we show how the Seebeck coefficient in silver Nafion and silver polystyrene-sulfonate are opposite in sign, allowing construction of a thermogalvanic device. With these ion conductors, we hope to open up a flexible pathway to waste heat recovery using materials typically studied for electrochemical applications.

  6. Long term flight electrodes

    NASA Technical Reports Server (NTRS)

    Mosier, B.

    1975-01-01

    The reproducibility, stability, and methods of preparation for the various types and forms of biomedical electrodes are discussed. A critical and selective compilation of information on biological and/or physiological electrodes is presented. A discussion of plant hydrocolloids, clays, hydrophyllic colloids, synthetic waxes, and acrylic polymers is included.

  7. Electrodes with fiber structure

    NASA Technical Reports Server (NTRS)

    Benczur-Uermoessy, G.; Berger, G.; Haschka, F.

    1986-01-01

    An electrode framework with a fiber structure, universally applicable in alkaline storage battery systems, was developed and readied for production. Storage batteries with these electrodes present higher energy and power densities and are economical to produce. The design is applicable to all rechargable storage batteries and might replace the previous variety of designs.

  8. Membrane Bioprobe Electrodes

    ERIC Educational Resources Information Center

    Rechnitz, Garry A.

    1975-01-01

    Describes the design of ion selective electrodes coupled with immobilized enzymes which operate either continuously or on drop-sized samples. Cites techniques for urea, L-phenylalanine and amygdalin. Micro size electrodes for use in single cells are discussed. (GH)

  9. Hollow Electrode Discharge Triodes

    NASA Astrophysics Data System (ADS)

    Schoenbach, K. H.; Peterkin, F. E.; Tessnow, T.

    1996-10-01

    The current through a direct current micro-hollow electrode (electrode hole diameter: 0.7 mm) discharge in argon was shown to be controllable by means of a third, external electrode placed close to the cathode opening. By increasing the potential of the positively biased control electrode from zero to 30 V the discharge current could be linearly reduced from 5 μA to 0.75 μA, at a discharge voltage of 300 V. The current-voltage characteristic of the micro-hollow electrode discharge was found to have a positive slope, allowing parallel discharge operation without ballast. By drilling holes through a metal-plated, dielectric film, an array of hollow electrode discharges could be generated. It was shown that each discharge responds individually to variations in the potential of the corresponding external control electrode. The simplicity of the electrode configuration and the possibility of linear, electrical control of the individual discharge currents offers the possibility to use these triode arrays in addressable flat panel displays (patent pending).

  10. Bifunctional catalytic electrode

    NASA Technical Reports Server (NTRS)

    Cisar, Alan (Inventor); Murphy, Oliver J. (Inventor); Clarke, Eric (Inventor)

    2005-01-01

    The present invention relates to an oxygen electrode for a unitized regenerative hydrogen-oxygen fuel cell and the unitized regenerative fuel cell having the oxygen electrode. The oxygen electrode contains components electrocatalytically active for the evolution of oxygen from water and the reduction of oxygen to water, and has a structure that supports the flow of both water and gases between the catalytically active surface and a flow field or electrode chamber for bulk flow of the fluids. The electrode has an electrocatalyst layer and a diffusion backing layer interspersed with hydrophilic and hydrophobic regions. The diffusion backing layer consists of a metal core having gas diffusion structures bonded to the metal core.

  11. Electrodes for microfluidic applications

    DOEpatents

    Crocker, Robert W.; Harnett, Cindy K.; Rognlien, Judith L.

    2006-08-22

    An electrode device for high pressure applications. These electrodes, designed to withstand pressure of greater than 10,000 psi, are adapted for use in microfluidic devices that employ electrokinetic or electrophoretic flow. The electrode is composed, generally, of an outer electrically insulating tubular body having a porous ceramic frit material disposed in one end of the outer body. The pores of the porous ceramic material are filled with an ion conductive polymer resin. A conductive material situated on the upper surface of the porous ceramic frit material and, thus isolated from direct contact with the electrolyte, forms a gas diffusion electrode. A metal current collector, in contact with the gas diffusion electrode, provides connection to a voltage source.

  12. HIGH VOLTAGE ELECTRODES

    DOEpatents

    Murray, J.J.

    1963-04-23

    S>This patent relates to electrode structure for creating an intense direct current electric field which may have a field strength of the order of two to three times that heretofore obtained, with automatic suppression of arcing. The positive electrode is a conventional conductive material such as copper while the negative electrode is made from a special material having a resistivity greater than that of good conductors and less than that of good insulators. When an incipient arc occurs, the moderate resistivity of the negative electrode causes a momentary, localized decrease in the electric field intensity, thus suppressing the flow of electrons and avoiding arcing. Heated glass may be utilized for the negative electrode, since it provides the desired combination of resistivity, capacity, dielectric strength, mechani-cal strength, and thermal stability. (AEC)

  13. Lab-on-a-Chip Sensor with Evaporated Bismuth Film Electrode for Anodic Stripping Voltammetry of Zinc

    PubMed Central

    Kang, Wenjing; Pei, Xing; Yue, Wei; Bange, Adam; Heineman, William R.; Papautsky, Ian

    2013-01-01

    In this work, we report on the development of a lab-on-a-chip electrochemical sensor that uses an evaporated bismuth electrode to detect zinc using square wave anodic stripping voltammetry. The microscale electrochemical cell consists of a bismuth working electrode, an integrated silver/silver chloride reference electrode, and a gold auxiliary electrode. The sensor demonstrated linear response in 0.1 M acetate buffer at pH 6 with zinc concentrations ranging from 1 μM to 30 μM and a calculated detection limit of 60 nM. The sensor was also able to successfully detect zinc in a bovine serum extract and the results were verified with independent AAS measurements. These results demonstrate the advantageous qualities of this lab-on-a-chip electrochemical sensor for clinical applications, which include a small sample volume (μL scale), reduced cost, short response time and high accuracy at low concentrations of analyte. PMID:24436575

  14. A facile patterning of silver nanowires using a magnetic printing method.

    PubMed

    Ahn, Taebin; Kim, Han-Jung; Lee, Jihye; Choi, Dae-Geun; Jung, Joo-Yun; Choi, Jun-Hyuk; Jeon, Sohee; Kim, Jong-Duk; Jeong, Jun-Ho

    2015-08-28

    Patterning of metal nanowires (NWs) is vital for the fabrication of NW-based, high-performance devices such as sensors, transparent conducting electrodes, and optoelectronics. However, the majority of existing patterning methods require complex and expensive technologies. For this reason, we report for the first time a facile and quick patterning method of silver (Ag) NWs using a magnetic printing method. We successfully demonstrated a patterned AgNW grid structure ona flexible substrate as transparent electrodes. The flexible AgNW grid electrode exhibited optical and electrical properties comparable to those of commercial transparent conducting electrodes.We believe our work will be broadly applicable to other NW-based devices such as sensors,energy storage devices, meta devices, nanoscale electronics, and optoelectronics.

  15. Monitoring plasmon-driven surface catalyzed reactions in situ using time-dependent surface-enhanced Raman spectroscopy on single particles of hierarchical peony-like silver microflowers

    NASA Astrophysics Data System (ADS)

    Tang, Xianghu; Cai, Wenya; Yang, Liangbao; Liu, Jinhuai

    2014-07-01

    Investigating the kinetics of catalytic reactions with surface-enhanced Raman scattering (SERS) on a single particle remains a significant challenge. In this study, the single particle of the constructed hierarchical peony-like silver microflowers (SMFs) with highly roughened surface led to the coupling of high catalytic activity with a strong SERS effect, which acts as an excellent bifunctional platform for in situ monitoring of surface catalytic reactions. The kinetics of the reaction of 4-nitrothiophenol (4-NTP) dimerizing into 4,4'-dimercaptoazobenzene (DMAB) was investigated and comparatively studied by using the SERS technique on a single particle of different morphologies of SMFs. The results indicate that a fully developed nanostructure of a hierarchical SMF has both larger SERS enhancement and apparent reaction rate constant k, which may be useful for monitoring and understanding the mechanism of plasmon-driven surface catalyzed reactions.Investigating the kinetics of catalytic reactions with surface-enhanced Raman scattering (SERS) on a single particle remains a significant challenge. In this study, the single particle of the constructed hierarchical peony-like silver microflowers (SMFs) with highly roughened surface led to the coupling of high catalytic activity with a strong SERS effect, which acts as an excellent bifunctional platform for in situ monitoring of surface catalytic reactions. The kinetics of the reaction of 4-nitrothiophenol (4-NTP) dimerizing into 4,4'-dimercaptoazobenzene (DMAB) was investigated and comparatively studied by using the SERS technique on a single particle of different morphologies of SMFs. The results indicate that a fully developed nanostructure of a hierarchical SMF has both larger SERS enhancement and apparent reaction rate constant k, which may be useful for monitoring and understanding the mechanism of plasmon-driven surface catalyzed reactions. Electronic supplementary information (ESI) available: Fig. S1-S12. See DOI

  16. The zinc electrode - Its behaviour in the nickel oxide-zinc accumulator

    NASA Astrophysics Data System (ADS)

    Certain aspects of zinc electrode reaction and behavior are investigated in view of their application to batteries. The properties of the zinc electrode in a battery system are discussed, emphasizing porous structure. Shape change is emphasized as the most important factor leading to limited battery cycle life. It is shown that two existing models of shape change based on electroosmosis and current distribution are unable to consistently describe observed phenomena. The first stages of electrocrystallization are studied and the surface reactions between the silver substrate and the deposited zinc layer are investigated. The reaction mechanism of zinc and amalgamated zinc in an alkaline electrolyte is addressed, and the batter system is studied to obtain information on cycling behavior and on the shape change phenomenon. The effect on cycle behavior of diferent amalgamation techniques of the zinc electrode and several additives is addressed. Impedance measurements on zinc electrodes are considered, and battery behavior is correlated with changes in the zinc electrode during cycling.

  17. Electrodes for sealed secondary batteries

    NASA Technical Reports Server (NTRS)

    Boies, D. B.; Child, F. T.

    1972-01-01

    Self-supporting membrane electrode structures, in which active ingredients and graphite are incorporated in a polymeric matrix, improve performance of electrodes in miniature, sealed, alkaline storage batteries.

  18. Layered electrode for electrochemical cells

    DOEpatents

    Swathirajan, Swathy; Mikhail, Youssef M.

    2001-01-01

    There is provided an electrode structure comprising a current collector sheet and first and second layers of electrode material. Together, the layers improve catalyst utilization and water management.

  19. Silver deposition on polypyrrole films electrosynthesised onto Nitinol alloy. Corrosion protection and antibacterial activity.

    PubMed

    Saugo, M; Flamini, D O; Brugnoni, L I; Saidman, S B

    2015-11-01

    The electrosynthesis of polypyrrole films onto Nitinol from sodium salicylate solutions of different concentrations is reported. The morphology and corrosion protection properties of the resulting coatings were examined and they both depend on the sodium salicylate concentration. The immobilisation of silver species in PPy films constituted by hollow rectangular microtubes was studied as a function of the polymer oxidation degree. The highest amount of silver was deposited when the coated electrode was prepolarised at -1.00V (SCE) before silver deposition, suggesting an increase in the amount of non-oxidised segments in the polymer. Finally, the antibacterial activity of the coating against the Gram positive Staphylococcus aureus and Staphylococcus epidermidis bacteria was evaluated. Both strains resulted sensitive to the modified coatings, obtaining a slightly better result against S. aureus.

  20. Biopolymer protected silver nanoparticles on the support of carbon nanotube as interface for electrocatalytic applications

    NASA Astrophysics Data System (ADS)

    Satyanarayana, M.; Kumar, V. Sunil; Gobi, K. Vengatajalabathy

    2016-04-01

    In this research, silver nanoparticles (SNPs) are prepared on the surface of carbon nanotubes via chitosan, a biopolymer linkage. Here chitosan act as stabilizing agent for nanoparticles and forms a network on the surface of carbon nanotubes. Synthesized silver nanoparticles-MWCNT hybrid composite is characterized by UV-Visible spectroscopy, XRD analysis, and FESEM with EDS to evaluate the structural and chemical properties of the nanocomposite. The electrocatalytic activity of the fabricated SNP-MWCNT hybrid modified glassy carbon electrode has been evaluated by cyclic voltammetry and electrochemical impedance analysis. The silver nanoparticles are of size ˜35 nm and are well distributed on the surface of carbon nanotubes with chitosan linkage. The prepared nanocomposite shows efficient electrocatalytic properties with high active surface area and excellent electron transfer behaviour.