Enhanced Raman spectroscopic study of the coordination chemistry of malononitrile on copper surfaces - Removal of nu(C=N) degeneracy through pi-coordination

NASA Technical Reports Server (NTRS)

Loo, B. H.; Lee, Y. G.; Frazier, D. O.

1985-01-01

Surface-enhanced Raman spectroscopy has been used to study the molecular interactions of malononitrile with copper electrode surfaces. The doubly degenerate CN stretching frequency at 2263/cm is removed when malononitrile adsorbs on copper. Two nu(CN) bands are observed at 2096 and 2204/cm at -0.6 V(SCE). The result shows that only one CN group is pi-coordinated with Cu, which contributes to the observed large shift (-167/cm) in nu(CN). The other CN group is not coordinated to the metal surface.

Tailoring gas-phase CO2 electroreduction selectivity to hydrocarbons at Cu nanoparticles

NASA Astrophysics Data System (ADS)

Merino-Garcia, I.; Albo, J.; Irabien, A.

2018-01-01

Copper-based surfaces appear as the most active catalysts for CO2 electroreduction to hydrocarbons, even though formation rates and efficiencies still need to be improved. The aim of the present work is to evaluate the continuous gas-phase CO2 electroreduction to hydrocarbons (i.e. ethylene and methane) at copper nanoparticulated-based surfaces, paying attention to particle size influence (ranging from 25-80 nm) on reaction productivity, selectivity, and Faraday efficiency (FE) for CO2 conversion. The effect of the current density and the presence of a microporous layer within the working electrode are then evaluated. Copper-based gas diffusion electrodes are prepared by airbrushing the catalytic ink onto carbon supports, which are then coupled to a cation exchange membrane (Nafion) in a membrane electrode assembly. The results show that the use of smaller copper nanoparticles (25 nm) leads to a higher ethylene production (1148 μmol m-2 s-1) with a remarkable high FE (92.8%), at the same time, diminishing the competitive hydrogen evolution reaction in terms of FE. This work demonstrates the importance of nanoparticle size on reaction selectivity, which may be of help to design enhanced electrocatalytic materials for CO2 valorization to hydrocarbons.

Microstructure of the regions on a plane copper electrode surface affected by a spark discharge in air in the point-plane gap

NASA Astrophysics Data System (ADS)

Tren'kin, A. A.; Karelin, V. I.; Shibitov, Yu. M.; Blinova, O. M.; Yasnikov, I. S.

2017-09-01

The microstructure of the regions affected by spark discharge on the surface of a plane copper electrode in atmospheric air in the point-plane gap has been studied using a scanning electron microscope for both the positive and negative polarity of the point electrode. It has been found that the affected regions have the shape of round spots or groups of spots with diameters of individual spots varying in the range of 20-200 μm. It has been revealed that the spots have an internal spatial structure in the form of an aggregate of concentric rings. These rings are aggregates of a large number of microscopic craters with diameters of 0.1-1.0 μm.

Electrochemical determination of copper ions in spirit drinks using carbon paste electrode modified with biochar.

PubMed

Oliveira, Paulo Roberto; Lamy-Mendes, Alyne C; Rezende, Edivaltrys Inayve Pissinati; Mangrich, Antonio Sálvio; Marcolino, Luiz Humberto; Bergamini, Márcio F

2015-03-15

This work describes for first time the use of biochar as electrode modifier in combination with differential pulse adsorptive stripping voltammetric (DPAdSV) techniques for preconcentration and determination of copper (II) ions in spirit drinks samples (Cachaça, Vodka, Gin and Tequila). Using the best set of the experimental conditions a linear response for copper ions in the concentration range of 1.5 × 10(-6) to 3.1 × 10(-5) mol L(-1) with a Limit of Detection (LOD) of 4.0 × 10(-7) mol L(-1). The repeatability of the proposed sensor using the same electrode surface was measured as 3.6% and 6.6% using different electrodes. The effect of foreign species on the voltammetric response was also evaluated. Determination of copper ions content in different samples of spirit drinks samples was also realized adopting inductively coupled plasma optical emission spectroscopy (ICP-OES) and the results achieved are in agreement at a 95% of confidence level. Copyright © 2014 Elsevier Ltd. All rights reserved.

Electrochemical study of the interaction between dsDNA and copper(I) using carbon paste and hanging mercury drop electrode.

PubMed

Stanić, Z; Girousi, S

2008-06-30

The interaction of copper(I) with double-stranded (ds) calf thymus DNA was studied in solution and at the electrode surface by means of transfer voltammetry using a carbon paste electrode (CPE) as working electrode in 0.2 M acetate buffer solution (pH 5.0). As a result of the interaction of Cu(I) between the base pairs of the dsDNA, the characteristic peaks of dsDNA, due to the oxidation of guanine and adenine, increased and after a certain concentration of Cu(I) a new peak at +1.37 V appeared, probably due to the formation of a purine-Cu(I) complex (dsDNA-Cu(I) complex). Accordingly, the interaction of copper(I) with calf thymus dsDNA was studied in solution as well as at the electrode surface using hanging mercury drop electrode (HMDE) by means of alternating current voltammetry (AC voltammetry) in 0.3 M NaCl and 50 mM sodium phosphate buffer (pH 8.5) as supporting electrolyte. Its interaction with DNA is shown to be time dependent. Significant changes in the characteristic peaks of dsDNA were observed after addition of higher concentration of Cu(I) to a solution containing dsDNA, as a result of the interaction between Cu(I) and dsDNA. All the experimental results indicate that Cu(I) can bind to DNA by electrostatic binding and form an association complex.

Achieving copper sulfide leaf like nanostructure electrode for high performance supercapacitor and quantum-dot sensitized solar cells

NASA Astrophysics Data System (ADS)

Durga, Ikkurthi Kanaka; Rao, S. Srinivasa; Reddy, Araveeti Eswar; Gopi, Chandu V. V. M.; Kim, Hee-Je

2018-03-01

Copper sulfide is an important multifunctional semiconductor that has attracted considerable attention owing to its outstanding properties and multiple applications, such as energy storage and electrochemical energy conversion. This paper describes a cost-effective and simple low-temperature solution approach to the preparation of copper sulfide for supercapacitors (SCs) and quantum-dot sensitized solar cells (QDSSCs). X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy confirmed that the nickel foam with a coriander leaf like nanostructure had been coated successfully with copper sulfide. As an electrode material for SCs, the CC-3 h showed excellent specific capacitance (5029.28 at 4 A g-1), energy density (169.73 W h kg-1), and superior cycling durability with 107% retention after 2000 cycles. Interestingly, the QDSSCs equipped with CC-2 h and CC-3 h counter electrodes (CEs) exhibited a maximum power conversion efficiency of 2.52% and 3.48%, respectively. The improved performance of the CC-3 h electrode was attributed mainly to the large surface area (which could contribute sufficient electroactive species), good conductivity, and high electrocatalytic activity. Overall, this work delivers novel insights into the use of copper sulfide and offers an important guidelines for the fabrication of next level energy storage and conversion devices.

Self-powered thin-film motion vector sensor

PubMed Central

Jing, Qingshen; Xie, Yannan; Zhu, Guang; Han, Ray P. S.; Wang, Zhong Lin

2015-01-01

Harnessing random micromeso-scale ambient energy is not only clean and sustainable, but it also enables self-powered sensors and devices to be realized. Here we report a robust and self-powered kinematic vector sensor fabricated using highly pliable organic films that can be bent to spread over curved and uneven surfaces. The device derives its operational energy from a close-proximity triboelectrification of two surfaces: a polytetrafluoroethylene film coated with a two-column array of copper electrodes that constitutes the mover and a polyimide film with the top and bottom surfaces coated with a two-column aligned array of copper electrodes that comprises the stator. During relative reciprocations, the electrodes in the mover generate electric signals of ±5 V to attain a peak power density of ≥65 mW m−2 at a speed of 0.3 ms−1. From our 86,000 sliding motion tests of kinematic measurements, the sensor exhibits excellent stability, repeatability and strong signal durability. PMID:26271603

Molybdenum-copper and tungsten-copper alloys and method of making

DOEpatents

Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

1989-05-23

Molybdenum-copper and tungsten-copper alloys are prepared by a consumable electrode method in which the electrode consists of a copper matrix with embedded strips of refractory molybdenum or tungsten. The electrode is progressively melted at its lower end with a superatmospheric inert gas pressure maintained around the liquifying electrode. The inert gas pressure is sufficiently above the vapor pressure of copper at the liquidus temperature of the alloy being formed to suppress boiling of liquid copper.

Molybdenum-copper and tungsten-copper alloys and method of making

DOEpatents

Schmidt, F.A.; Verhoeven, J.D.; Gibson, E.D.

1989-05-23

Molybdenum-copper and tungsten-copper alloys are prepared by a consumable electrode method in which the electrode consists of a copper matrix with embedded strips of refractory molybdenum or tungsten. The electrode is progressively melted at its lower end with a superatmospheric inert gas pressure maintained around the liquefying electrode. The inert gas pressure is sufficiently above the vapor pressure of copper at the liquidus temperature of the alloy being formed to suppress boiling of liquid copper. 6 figs.

Texturing Copper To Reduce Secondary Emission Of Electrons

NASA Technical Reports Server (NTRS)

Jensen, Kenneth A.; Curren, Arthur N.; Roman, Robert F.

1995-01-01

Ion-beam process produces clean, deeply textured surfaces on copper substrates with reduced secondary electron emission. In process, molybdenum ring target positioned above and around copper substrate. Target potential repeatedly switched on and off. Switching module described in "High-Voltage MOSFET Switching Circuit" (LEW-15986). Useful for making collector electrodes for traveling-wave-tube and klystron microwave amplifiers, in which secondary emission of electrons undesirable because of reducing efficiency.

Catalyst surfaces for the chromous/chromic redox couple

NASA Technical Reports Server (NTRS)

Giner, J. D.; Cahill, K. J. (Inventor)

1980-01-01

An electricity producing cell of the reduction-oxidation (REDOX) type is described. The cell is divided into two compartments by a membrane, each compartment containing a solid inert electrode. A ferrous/ferric couple in a chloride solution serves as a cathode fluid which is circulated through one of the compartments to produce a positive electric potential disposed therein. A chromic/chromous couple in a chloride solution serves as an anode fluid which is circulated through the second compartment to produce a negative potential on an electrode disposed therein. The electrode is an electrically conductive, inert material plated with copper, silver or gold. A thin layer of lead plates onto the copper, silver or gold layer when the cell is being charged, the lead ions being available from lead chloride which was added to the anode fluid. If the REDOX cell is then discharged, the current flows between the electrodes causing the lead to deplate from the negative electrode and the metal coating on the electrode will act as a catalyst to cause increased current density.

The Influence of Marine Microfouling on the Corrosion Behaviour of Passive Materials and Copper Alloys

DTIC Science & Technology

2008-01-02

to organometallic catalysis, acidification of the electrode surface, the combined effects of elevated H20 2 and decreased pH and the production of...Ennoblement in marine waters has been ascribed to depolarization of the oxygen reduction reaction due to organometallic catalysis, acidification of the...organometallic catalysis, acidification of the electrode surface, the combined effects of elevated hydrogen peroxide (H202) and decreased pH and the production

A copper ion-selective electrode with high selectivity prepared by sol-gel and coated wire techniques.

PubMed

Mazloum Ardakani, M; Salavati-Niasari, M; Khayat Kashani, M; Ghoreishi, S M

2004-03-01

A sol-gel electrode and a coated wire ion-selective poly(vinyl chloride) membrane, based on thiosemicarbazone as a neutral carrier, were successfully developed for the detection of Cu (II) in aqueous solutions. The sol-gel electrode and coated electrode exhibited linear response with Nernstian slopes of 29.2 and 28.1 mV per decade respectively, within the copper ion concentration ranges 1.0 x 10(-5) - 1.0 x 10(-1) M and 6.0 x 10(-6) - 1.0 x 10(-1) M for coated and sol-gel sensors. The coated and sol-gel electrodes show detection limits of 3.0 x 10(-6) and 6.0 x 10(-6) M respectively. The electrodes exhibited good selectivities for a number of alkali, alkaline earth, transition and heavy metal ions. The proposed electrodes have response times ranging from 10-50 s to achieve a 95% steady potential for Cu2+ concentration. The electrodes are suitable for use in aqueous solutions over a wide pH range (4-7.5). Applications of these electrodes for the determination of copper in real samples, and as an indicator electrode for potentiometric titration of Cu2+ ion using EDTA, are reported. The lifetimes of the electrodes were tested over a period of six months to investigate their stability. No significant change in the performance of the sol-gel electrode was observed over this period, but after two months the coated wire copper-selective electrode exhibited a gradual decrease in the slope. The selectivity of the sol-gel electrode was found to be better than that of the coated wire copper-selective electrode. Based on these results, a novel sol-gel copper-selective electrode is proposed for the determination of copper, and applied to real sample assays.

Surface Chemistry and Tribology of Copper Surfaces in Carbon Dioxide and Water Vapor Environments

DTIC Science & Technology

2011-02-23

state that the copper brushes in the superconducting homopolar motor experience wear at rates greater than 3X10" wear /distance traveled when biased...positively. It has been found the motor operates best in an atmosphere of carbon dioxide and water vapor. The objective of our research therefore is...possible to prepare different chemical states of the Cu, as those produced in the motor electrodes under positive and negative bias. In situ XAS

Copper Electrodeposition on a Magnesium Alloy (AZ80) with a U-Shaped Surface

PubMed Central

Huang, Ching An; Yeh, Yu Hu; Lin, Che Kuan; Hsieh, Chen Yun

2014-01-01

Cu electrodeposition was performed on a cylindrical AZ80 substrate with a U-shaped surface. A uniform deposition of Cu was achieved on an AZ80 electrode via galvanostatic etching, followed by Cu electrodeposition in an eco-friendly alkaline Cu plating bath. Improper wetting and lower rotational speeds of the AZ80 electrode resulted in an uneven Cu deposition at the inner upper site of the U-shaped surface during the Cu electroplating process. This wetting effect could be deduced from the variation in the anodic potential during the galvanostatic etching. The corrosion resistance of the Cu-deposited AZ80 electrode can be considerably improved after Ni electroplating. PMID:28788252

Development of an all-metal thick-film cost-effective metallization system for solar cells

NASA Technical Reports Server (NTRS)

Ross, B.

1981-01-01

Screened electrodes made from fluorocarbon activated copper paste and silver fluoride activated copper paste, tape adhesion and scratch tests were studied. Experiments were conducted with variations in past parameters, firing conditions, including gas ambients, furnace furniture, silicon surface and others. A liquid medium intended to provide transport during the carbon fluoride decomposition, is incorporated in the paste.

Catalyst surfaces for the chromous/chromic redox couple

NASA Technical Reports Server (NTRS)

Giner, J. D.; Cahill, K. J. (Inventor)

1981-01-01

An electricity producing cell of the reduction-oxidation (REDOX) type divided into two compartments by a membrane is disclosed. A ferrous/ferric couple in a chloride solution serves as a cathode fluid to produce a positive electric potential. A chromic/chromous couple in a chloride solution serves as an anode fluid to produce a negative potential. The electrode is an electrically conductive, inert material plated with copper, silver or gold. A thin layer of lead plates onto the copper, silver or gold layer when the cell is being charged, the lead ions being available from lead chloride which has been added to the anode fluid. If the REDOX cell is then discharged, the lead deplates from the negative electrode and the metal coating on the electrode acts as a catalyst to increase current density.

High-surface-area architectures for improved charge transfer kinetics at the dark electrode in dye-sensitized solar cells.

PubMed

Hoffeditz, William L; Katz, Michael J; Deria, Pravas; Martinson, Alex B F; Pellin, Michael J; Farha, Omar K; Hupp, Joseph T

2014-06-11

Dye-sensitized solar cell (DSC) redox shuttles other than triiodide/iodide have exhibited significantly higher charge transfer resistances at the dark electrode. This often results in poor fill factor, a severe detriment to device performance. Rather than moving to dark electrodes of untested materials that may have higher catalytic activity for specific shuttles, the surface area of platinum dark electrodes could be increased, improving the catalytic activity by simply presenting more catalyst to the shuttle solution. A new copper-based redox shuttle that experiences extremely high charge-transfer resistance at conventional Pt dark electrodes yields cells having fill-factors of less than 0.3. By replacing the standard Pt dark electrode with an inverse opal Pt electrode fabricated via atomic layer deposition, the dark electrode surface area is boosted by ca. 50-fold. The resulting increase in interfacial electron transfer rate (decrease in charge-transfer resistance) nearly doubles the fill factor and therefore the overall energy conversion efficiency, illustrating the utility of this high-area electrode for DSCs.

Co-sputter deposited nickel-copper bimetallic nanoalloy embedded carbon films for electrocatalytic biomarker detection

NASA Astrophysics Data System (ADS)

Shiba, Shunsuke; Kato, Dai; Kamata, Tomoyuki; Niwa, Osamu

2016-06-01

We report the fabrication of a nickel (Ni)-copper (Cu) bimetallic nanoalloy (~3 nm) embedded carbon film electrode with the unbalanced magnetron (UBM) co-sputtering technique, which requires only a one-step process at room temperature. Most of each nanoalloy body was firmly embedded in a chemically stable carbon matrix with an atomically flat surface (Ra: 0.21 nm), suppressing the aggregation and/or detachment of the nanoalloy from the electrode surface. The nanoalloy size and composition can be controlled simply by individually controlling the target powers of carbon, Ni and Cu, which also makes it possible to localize the nanoalloys near the electrode surface. This electrode exhibited excellent electrocatalytic activity for d-mannitol, which should be detected with a low detection limit in urine samples for the diagnosis of severe intestinal diseases. With a Ni/Cu ratio of around 64/36, the electrocatalytic current per metal area was 3.4 times larger than that of an alloy film electrode with a similar composition (~70/30). This improved electrocatalytic activity realized higher stability (n = 60, relative standard deviation (RSD): 4.6%) than the alloy film (RSD: 32.2%) as demonstrated by continuous measurements of d-mannitol.We report the fabrication of a nickel (Ni)-copper (Cu) bimetallic nanoalloy (~3 nm) embedded carbon film electrode with the unbalanced magnetron (UBM) co-sputtering technique, which requires only a one-step process at room temperature. Most of each nanoalloy body was firmly embedded in a chemically stable carbon matrix with an atomically flat surface (Ra: 0.21 nm), suppressing the aggregation and/or detachment of the nanoalloy from the electrode surface. The nanoalloy size and composition can be controlled simply by individually controlling the target powers of carbon, Ni and Cu, which also makes it possible to localize the nanoalloys near the electrode surface. This electrode exhibited excellent electrocatalytic activity for d-mannitol, which should be detected with a low detection limit in urine samples for the diagnosis of severe intestinal diseases. With a Ni/Cu ratio of around 64/36, the electrocatalytic current per metal area was 3.4 times larger than that of an alloy film electrode with a similar composition (~70/30). This improved electrocatalytic activity realized higher stability (n = 60, relative standard deviation (RSD): 4.6%) than the alloy film (RSD: 32.2%) as demonstrated by continuous measurements of d-mannitol. Electronic supplementary information (ESI) available: The concept of UBM co-sputtering for fabricating nanoalloy embedded carbon films. HRTEM images of the NiNP and Ni32Cu68 nanoalloy embedded carbon films. The experimental conditions for sputter deposition, HRTEM, HAADF-STEM, STEM-EDS measurements and continuous flow injection analysis. XPS analysis of the nanoalloy embedded carbon film. Repeated CVs of both the nanoalloy embedded carbon film and the alloy film. Amperometric detection of d-mannitol in the presence of chloride ions. See DOI: 10.1039/c6nr02287a

Patterned self-assembled monolayers of alkanethiols on copper nanomembranes by submerged laser ablation

NASA Astrophysics Data System (ADS)

Rhinow, Daniel; Hampp, Norbert A.

2012-06-01

Self-assembled monolayers (SAMs) of alkanethiols are major building blocks for nanotechnology. SAMs provide a functional interface between electrodes and biomolecules, which makes them attractive for biochip fabrication. Although gold has emerged as a standard, copper has several advantages, such as compatibility with semiconductors. However, as copper is easily oxidized in air, patterning SAMs on copper is a challenging task. In this work we demonstrate that submerged laser ablation (SLAB) is well-suited for this purpose, as thiols are exchanged in-situ, avoiding air exposition. Using different types of ω-substituted alkanethiols we show that alkanethiol SAMs on copper surfaces can be patterned using SLAB. The resulting patterns were analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Both methods indicate that the intense laser beam promotes the exchange of thiols at the copper surface. Furthermore, we present a procedure for the production of free-standing copper nanomembranes, oxidation-protected by alkanethiol SAMs. Incubation of copper-coated mica in alkanethiol solutions leads to SAM formation on both surfaces of the copper film due to intercalation of the organic molecules. Corrosion-protected copper nanomembranes were floated onto water, transferred to electron microscopy grids, and subsequently analyzed by electron energy loss spectroscopy (EELS).

Secondary-electron-emission losses in multistage depressed collectors and traveling-wave-tube efficiency improvements with carbon collector electrode surfaces

NASA Technical Reports Server (NTRS)

Ramins, P.; Ebihara, B. T.

1986-01-01

Secondary-electron-emission losses in multistage depressed collectors (MDC's) and their effects on overall traveling-wave-tube (TWT) efficiency were investigated. Two representative TWT's and several computer-modeled MDC's were used. The experimental techniques provide the measurement of both the TWT overall and the collector efficiencies. The TWT-MDC performance was optimized and measured over a wide range of operating conditions, with geometrically identical collectors, which utilized different electrode surface materials. Comparisons of the performance of copper electrodes to that of various forms of carbon, including pyrolytic and iisotropic graphites, were stressed. The results indicate that: (1) a significant improvement in the TWT overall efficiency was obtained in all cases by the use of carbon, rather than copper electrodes, and (2) that the extent of this efficiency enhancement depended on the characteristics of the TWT, the TWT operating point, the MDC design, and collector voltages. Ion textured graphite was found to be particularly effective in minimizing the secondary-electron-emission losses. Experimental and analytical results, however, indicate that it is at least as important to provide a maximum amount of electrostatic suppression of secondary electrons by proper MDC design. Such suppression, which is obtained by ensuring that a substantial suppressing electric field exists over the regions of the electrodes where most of the current is incident, was found to be very effective. Experimental results indicate that, with proper MDC design and the use of electrode surfaces with low secondary-electron yield, degradation of the collector efficiency can be limited to a few percent.

Study of Copper and Purine-Copper Complexes on Modified Carbon Electrodes by Cyclic and Elimination Voltammetry

PubMed Central

Trnkova, Libuse; Zerzankova, Lenka; Dycka, Filip; Mikelova, Radka; Jelen, Frantisek

2008-01-01

Using a paraffin impregnated graphite electrode (PIGE) and mercury-modified pyrolytic graphite electrode with basal orientation (Hg-PGEb) copper(II) and Cu(II)-DNA purine base solutions have been studied by cyclic (CV) and linear sweep voltammetry (LSV) in connection with elimination voltammetry with linear scan (EVLS). In chloride and bromide solutions (pH 6), the redox process of Cu(II) proceeded on PIGE with two cathodic and two anodic potentially separated signals. According to the elimination function E4, the first cathodic peak corresponds to the reduction Cu(II) + e- → Cu(I) with the possibility of fast disproportionation 2Cu(I) → Cu(II)+ Cu(0). The E4 of the second cathodic peak signalized an electrode process controlled by a surface reaction. The electrode system of Cu(II) on Hg-PGEb in borate buffer (pH 9.2) was characterized by one cathodic and one anodic peak. Anodic stripping voltammetry (ASV) on PIGE and cathodic stripping voltammetry (CSV) on Hg-PGEb were carried out at potentials where the reduction of copper ions took place and Cu(I)-purine complexes were formed. By using ASV and CSV in combination with EVLS, the sensitivity of Cu(I)-purine complex detection was enhanced relative to either ASV or CSV alone, resulting in higher peak currents of more than one order of magnitude. The statistical treatment of CE data was used to determine the reproducibility of measurements. Our results show that EVLS in connection with the stripping procedure is useful for both qualitative and quantitative microanalysis of purine derivatives and can also reveal details of studied electrode processes. PMID:27879715

Determination of nicotine by surface-enhanced Raman scattering (SERS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barber, T.E.; List, M.S.; Haas, J.W. III

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 10more » 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.« less

Development of an all-metal thick film cost effective metallization system for solar cells. Final report, May 1980-January 1983

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, B.; Parker, J.

1983-12-01

Properties of copper pastes did not reproduce earlier results in rheology and metallurgy. Electrodes made with pastes produced under the previous contract were analyzed and raw material characteristics were compared. A needle-like structure was observed on the earlier electroded solar cells, and was identified as eutectic copper-silicon. Experiments were conducted with variations in paste parameters, firing conditions, including gas ambients, furnace furniture, silicon surface and others to improve performance characteristics. Improved adhesion with copper pastes containing silver fluoride, as well as those containing fluorocarbon powder was obtained. Front contact experiments were done with silver fluoride activated pastes on bare silicon,more » silicon oxide and silicon nitride coated silicon wafers. Adhesion of pastes with AgF on silicon nitride coated wafers was good, but indications were that all cells were shunted and the conclusion was that these systems were unsuitable for front contacts. Experiments with aluminum back surfaces and screened contacts to that surface were begun. Low temperature firing tended to result in S shaped IV curves. This was attributed to a barrier formed at the silicon-copper interface. A cooperative experiment was initiated on the effect of heat-treatments in various atmospheres on the hydrogen profile of silicon surfaces. Contact theory was explored to determine the role of various parameters on tunneling and contact resistance. Data confirm that the presence of eutectic Al-Si additions are beneficial for low contact resistance and fill factors in back contacts. Copper pastes with different silver fluoride additions were utilized as front contacts at two temperatures. Data shows various degrees of shunting. Finally, an experiment was run with carbon monoxide gas used as the reducing ambient during firing.« less

Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation.

PubMed

Zhang, Peili; Li, Lin; Nordlund, Dennis; Chen, Hong; Fan, Lizhou; Zhang, Biaobiao; Sheng, Xia; Daniel, Quentin; Sun, Licheng

2018-01-26

Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180 mV at a current density of 10 mA cm -2 . The core-shell NiFeCu electrode exhibits pH-dependent oxygen evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.

Silicon-embedded copper nanostructure network for high energy storage

DOEpatents

Yu, Tianyue

2018-01-23

Provided herein are nanostructure networks having high energy storage, electrochemically active electrode materials including nanostructure networks having high energy storage, as well as electrodes and batteries including the nanostructure networks having high energy storage. According to various implementations, the nanostructure networks have high energy density as well as long cycle life. In some implementations, the nanostructure networks include a conductive network embedded with electrochemically active material. In some implementations, silicon is used as the electrochemically active material. The conductive network may be a metal network such as a copper nanostructure network. Methods of manufacturing the nanostructure networks and electrodes are provided. In some implementations, metal nanostructures can be synthesized in a solution that contains silicon powder to make a composite network structure that contains both. The metal nanostructure growth can nucleate in solution and on silicon nanostructure surfaces.

Enhanced electrochemical performances with a copper/xylose-based carbon composite electrode

NASA Astrophysics Data System (ADS)

Sirisomboonchai, Suchada; Kongparakul, Suwadee; Nueangnoraj, Khanin; Zhang, Haibo; Wei, Lu; Reubroycharoen, Prasert; Guan, Guoqing; Samart, Chanatip

2018-04-01

Copper/carbon (Cu/C) composites were prepared through the simple and environmentally benign hydrothermal carbonization of xylose in the presence of Cu2+ ions. The morphology, specific surface area, phase structure and chemical composition were investigated. Using a three-electrode system in 0.1 M H2SO4 aqueous electrolyte, the Cu/C composite (10 wt% Cu) heat-treated at 600 °C gave the highest specific capacitance (316.2 and 350.1 F g-1 at 0.5 A g-1 and 20 mV s-1, respectively). The addition of Cu was the major factor in improving the electrochemical performance, enhancing the specific capacitance more than 30 times that of the C without Cu. Therefore, the Cu/C composite presented promising results in improving biomass-based C electrodes for supercapacitors.

Silicon-embedded copper nanostructure network for high energy storage

DOEpatents

Yu, Tianyue

2016-03-15

Provided herein are nanostructure networks having high energy storage, electrochemically active electrode materials including nanostructure networks having high energy storage, as well as electrodes and batteries including the nanostructure networks having high energy storage. According to various implementations, the nanostructure networks have high energy density as well as long cycle life. In some implementations, the nanostructure networks include a conductive network embedded with electrochemically active material. In some implementations, silicon is used as the electrochemically active material. The conductive network may be a metal network such as a copper nanostructure network. Methods of manufacturing the nanostructure networks and electrodes are provided. In some implementations, metal nanostructures can be synthesized in a solution that contains silicon powder to make a composite network structure that contains both. The metal nanostructure growth can nucleate in solution and on silicon nanostructure surfaces.

The Unusual Colour of Copper Deposited on a Graphite Electrode in an Aqueous Solution of CuSO[subscript 4

ERIC Educational Resources Information Center

Petrusevski, Vladimir M.; Stojanovska, Marina

2010-01-01

The colour of the copper layer deposited on a graphite electrode during electrolysis of an aqueous solution of copper(II) sulfate looks whitish-grey when inspected in situ. Taking the electrode out of the solution reveals the familiar orange-red colour of deposited copper. The explanation is found in terms of the almost ideal complementary colours…

Characterization of nanostructured surfaces generated by reconstitution of the porin MspA from Mycobacterium smegmatis.

PubMed

Wörner, Michael; Lioubashevski, Oleg; Basel, Matthew T; Niebler, Sandra; Gogritchiani, Eliso; Egner, Nicole; Heinz, Christian; Hoferer, Jürgen; Cipolloni, Michela; Janik, Katharine; Katz, Evgeny; Braun, Andre M; Willner, Itamar; Niederweis, Michael; Bossmann, Stefan H

2007-06-01

Nanostructures with long-term stability at the surface of gold electrodes are generated by reconstituting the porin MspA from Mycobacterium smegmatis into a specially designed monolayer of long-chain lipid surfactant on gold. Tailored surface coverage of gold electrodes with long-chain surfactants is achieved by electrochemically assisted deposition of organic thiosulfates (Bunte salts). The subsequent reconstitution of the octameric-pore MspA is guided by its extraordinary self-assembling properties. Importantly, electrochemical reduction of copper(II) yields copper nanoparticles within the MspA nanopores. Electrochemical impedance spectroscopy, reflection electron microscopy, and atomic force microscopy (AFM) show that: 1) the MspA pores within the self-assembled monolayer (SAM) are monodisperse and electrochemically active, 2) MspA reconstitutes in SAMs and with a 10-nm thickness, 3) AFM is a suitable method to detect pores within SAMs, and 4) the electrochemical reduction of Cu2+ to Cu0 under overpotential conditions starts within the MspA pores.

Supramolecular Porphyrin Cages Assembled at Molecular–Materials Interfaces for Electrocatalytic CO Reduction

PubMed Central

2017-01-01

Conversion of carbon monoxide (CO), a major one-carbon product of carbon dioxide (CO2) reduction, into value-added multicarbon species is a challenge to addressing global energy demands and climate change. Here we report a modular synthetic approach for aqueous electrochemical CO reduction to carbon–carbon coupled products via self-assembly of supramolecular cages at molecular–materials interfaces. Heterobimetallic cavities formed by face-to-face coordination of thiol-terminated metalloporphyrins to copper electrodes through varying organic struts convert CO to C2 products with high faradaic efficiency (FE = 83% total with 57% to ethanol) and current density (1.34 mA/cm2) at a potential of −0.40 V vs RHE. The cage-functionalized electrodes offer an order of magnitude improvement in both selectivity and activity for electrocatalytic carbon fixation compared to parent copper surfaces or copper functionalized with porphyrins in an edge-on orientation. PMID:28979945

Supramolecular Porphyrin Cages Assembled at Molecular–Materials Interfaces for Electrocatalytic CO Reduction

DOE PAGES

Gong, Ming; Cao, Zhi; Liu, Wei; ...

2017-09-13

Conversion of carbon monoxide (CO), a major one-carbon product of carbon dioxide (CO 2) reduction, into value-added multicarbon species is a challenge to addressing global energy demands and climate change. Here in this paper, we report a modular synthetic approach for aqueous electrochemical CO reduction to carbon-carbon coupled products via self-assembly of supramolecular cages at molecular-materials interfaces. Heterobimetallic cavities formed by face-to-face coordination of thiol-terminated metalloporphyrins to copper electrodes through varying organic struts convert CO to C2 products with high faradaic efficiency (FE = 83% total with 57% to ethanol) and current density (1.34 mA/cm 2) at a potential ofmore » -0.40 V vs RHE. The cage-functionalized electrodes offer an order of magnitude improvement in both selectivity and activity for electrocatalytic carbon fixation compared to parent copper surfaces or copper functionalized with porphyrins in an edge-on orientation.« less

Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Peili; Li, Lin; Nordlund, Dennis

Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here in this paper, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180 mV at a current density of 10 mA cm -2. The core-shell NiFeCu electrode exhibits pH-dependent oxygenmore » evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.« less

Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation

DOE PAGES

Zhang, Peili; Li, Lin; Nordlund, Dennis; ...

2018-01-26

Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here in this paper, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180 mV at a current density of 10 mA cm -2. The core-shell NiFeCu electrode exhibits pH-dependent oxygenmore » evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.« less

Hierarchical nano-on-micro copper with enhanced catalytic activity towards electro-oxidation of hydrazine

NASA Astrophysics Data System (ADS)

Yan, Xiaodong; Liu, Yuan; Scheel, Kyle R.; Li, Yong; Yu, Yunhua; Yang, Xiaoping; Peng, Zhonghua

2018-03-01

The electrochemical properties of catalyst materials are highly dependent on the materials structure and architecture. Herein, nano-on-micro Cu electrodes are fabricated by growing Cu microcrystals on Ni foam substrate, followed by introducing Cu nanocrystals onto the surface of the Cu microcrystals. The introduction of Cu nanocrystals onto the surface of Cu microcrystals is shown to dramatically increase the electrochemically active surface area and thus significantly enhances the catalytic activity of the catalyst electrode towards electro-oxidation of hydrazine. The onset potential (-1.04 V vs. Ag/AgCl) of the nano-on-micro Cu electrode is lower than those of the reported Cu-based catalysts under similar testing conditions, and a current density of 16 mA·cm-2, which is 2 times that of the microsized Cu electrode, is achieved at a potential of -0.95 V vs. Ag/AgCl. Moreover, the nano-on-micro Cu electrode demonstrates good long-term stability.

Copper Antimonide Nanowire Array Lithium Ion Anodes Stabilized by Electrolyte Additives.

PubMed

Jackson, Everett D; Prieto, Amy L

2016-11-09

Nanowires of electrochemically active electrode materials for lithium ion batteries represent a unique system that allows for intensive investigations of surface phenomena. In particular, highly ordered nanowire arrays produced by electrodeposition into anodic aluminum oxide templates can lead to new insights into a material's electrochemical performance by providing a high-surface-area electrode with negligible volume expansion induced pulverization. Here we show that for the Li-Cu x Sb ternary system, stabilizing the surface chemistry is the most critical factor for promoting long electrode life. The resulting solid electrolyte interphase is analyzed using a mix of electron microscopy, X-ray photoelectron spectroscopy, and lithium ion battery half-cell testing to provide a better understanding of the importance of electrolyte composition on this multicomponent alloy anode material.

CSSC Fish Barrier Simulated Rescuer Touch Point Results, Operating Guidance, and Recommendations for Rescuer Safety

DTIC Science & Technology

2011-09-01

Testing Input electrodes consisting of 1/2” diameter, 6” long copper rods were wired to separate conductors of a shielded, commercially available...underwater-rated electrical cable (three-conductor, shielded, shipboard cable (TSS-2), 18 American Wire Gauge (AWG) stranded copper ). Electrode pairs...sandpaper prior to use to ensure the best electrical continuity between the water and electrode by removing any copper oxide. This electrode

ESD coating of copper with TiC and TiB2 based ceramic matrix composites

NASA Astrophysics Data System (ADS)

Talas, S.; Mertgenç, E.; Gökçe, B.

2016-08-01

In automotive industry, the spot welding is a general practice to join smaller sections of a car. This welding is specifically carried out in short time and in an elevated number with certain pressure applied on copper electrodes. In addition, copper electrodes are expected to endure against cyclic mechanical pressure and temperature that is released during the passage of the current. The deformation and oxidation behaviour of copper electrodes during service appear with increasing temperature of medium and they also need to be cleaned and cooled or replaced for the continuation of joining process. The coating of copper electrodes with ceramic matrix composites can provide alternative excellent high temperature strength and ensures both economic and efficient use of resources. This study shows that the ESD coating of copper electrodes with a continuous film of ceramic phase ensures an improved resistance to thermal effects during the service and the change in content of film may be critical for cyclic alloying.

Sheath-flow electrochemical detection of amino acids with a copper wire electrode in capillary electrophoresis.

PubMed

Inoue, Junji; Kaneta, Takashi; Imasaka, Totaro

2012-09-01

Here, we report the detection of native amino acids using a sheath-flow electrochemical detector with a working electrode made of copper wire. A separation capillary that was inserted into a platinum tube in the detector acted as a grounded electrode for electrophoresis and as a flow channel for sheath liquid. Sheath liquid flowed outside the capillary to support the transport of the separated analytes to the working electrode for electrochemical detection. The copper wire electrode was aligned at the outlet of the capillary in a wall-jet configuration. Amino acids injected into the capillary were separated following elution from the end of the capillary and detection by the copper electrode. Three kinds of copper electrodes with different diameters-50, 125, and 300 μm-were examined to investigate the effect of the electrode diameter on sensitivity. The peak widths of the analytes were independent of the diameter of the working electrode, while the 300-μm electrode led to a decrease in the signal-to-noise ratio compared with the 50- and 125-μm electrodes, which showed no significant difference. The flow rate of the sheath liquid was also varied to optimize the detection conditions. The limits of detection for amino acids ranged from 4.4 to 27 μM under optimal conditions. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Additive-mediated electrochemical synthesis of platelike copper crystals for methanol electrooxidation.

PubMed

Venkatasubramanian, Rajesh; He, Jibao; Johnson, Michael W; Stern, Ilan; Kim, Dae Ho; Pesika, Noshir S

2013-10-29

A room-temperature electrochemical approach to synthesizing anisotropic platelike copper microcrystals and nanocrystals in the presence of potassium bromide is presented. Morphological and elemental characterization was performed using SEM, TEM, and XRD to confirm the anisotropic morphology and crystal structure of the synthesized copper particles. A possible mechanism for explaining the anisotropic crystal growth is proposed on the basis of the preferential adsorption of bromide ions to selective crystal faces. The shape-dependent electrocatalytic property of copper particles is demonstrated by its enhanced catalytic activity for methanol oxidation. Further development of such anisotropic copper particles localized on an electrode surface will lead us to find a suitable alternative for noble metal-based electrocatalysts for the methanol oxidation reaction relevant to fuel cells.

Electrodeposition of gold particles on aluminum substrates containing copper.

PubMed

Olson, Tim S; Atanassov, Plamen; Brevnov, Dmitri A

2005-01-27

Electrodeposition of adhesive metal films on aluminum is traditionally preceded by the zincate process, which activates the aluminum surface. This paper presents an alternative approach for activation of aluminum by using films containing 99.5% aluminum and 0.5% copper. Aluminum/copper films are made amenable for subsequent electrodeposition by anodization followed by chemical etching of aluminum oxide. The electrodeposition of gold is monitored with electrochemical impedance spectroscopy (EIS). Analysis of EIS data suggests that electrodeposition of gold increases the interfacial capacitance from values typical for electrodes with thin oxide layers to values typical for metal electrodes. Scanning electron microscopy examination of aluminum/copper films following gold electrodeposition shows the presence of gold particles with densities of 10(5)-10(7) particles cm(-2). The relative standard deviation of mean particle diameters is approximately 25%. Evaluation of the micrographs suggests that the electrodeposition occurs by instantaneous nucleation followed by growth of three-dimensional semispherical particles. The gold particles, which are electrically connected to the conductive aluminum/copper film, support a reversible faradaic process for a soluble redox couple. The deposited gold particles are suitable for subsequent metallization of aluminum and fabrication of particle-type films with interesting catalytic, electrical, and optical properties.

Surface study of films formed on copper and brass at open circuit potential

NASA Astrophysics Data System (ADS)

Procaccini, R.; Schreiner, W. H.; Vázquez, M.; Ceré, S.

2013-03-01

The corrosion resistance of Cu-Zn alloys strongly depends on the quality of the protective passive film. This study focuses on the influence of Zn on the composition of oxide films on copper and brass (Cu77Zn21Al2) in borax 0.1 mol L-1 (pH 9.2) solution, where the solubility of copper oxides is minimal. The effect of the presence of chloride ions at low concentration (0.01 mol L-1) in the electrolyte was also evaluated. Both conditions were studied using a set of different electrochemical, optical and surface techniques such as cyclic voltammetry, differential reflectance, X-ray photoelectron spectroscopy and Raman spectroscopy. A duplex Cu2O/CuO layer forms on copper at potentials positive to the open circuit potential (OCP), while in the case of brass, zinc compounds are also incorporated to the surface film. It also became evident that a surface film can be formed on these materials even at potentials negative to the OCP. Zn(II) species are the main constituents of the films growing on brass, while copper oxides are incorporated to the surface film when approaching the OCP. The presence of chloride ions at low concentrations contributes to the dissolution of the oxo-hydroxides formed during the early stages of the aging process at open circuit potential. Also, copper chloro-compounds are formed, as shown by Raman spectroscopy for both copper and brass electrodes.

Electrode systems for in situ vitrification

DOEpatents

Buelt, James L.; Carter, John G.; Eschbach, Eugene A.; FitzPatrick, Vincent F.; Koehmstedt, Paul L.; Morgan, William C.; Oma, Kenton H.; Timmerman, Craig L.

1990-01-01

An electrode comprising a molybdenum rod is received within a conductive collar formed of graphite. The molybdenum rod and the graphite collar may be physically joined at the bottom. A pair of such electrodes are placed in soil containing buried waste material and an electric current is passed therebetween for vitrifying the soil. The graphite collar enhances the thermal conductivity of the combination, bringing heat to the surface, and preventing formation of a cold cap of material above the ground surface. The annulus between the molybdenum rod electrode and the graphite collar is suitably filled with a conductive ceramic powder that sinters upon the molybdenum rod, protecting the same from oxidation as graphite material is consumed, or a metal powder which liquefies at operating temperatures. The center of the molybdenum rod, used with a collar of separately, can be hollow and filled with a powdered metal, such as copper, which liquefies at operating temperatures. Connection to electrodes can be provided below ground level to avoid open circuit due to electrode deterioration, or sacrificial electrodes may be employed when operation is started. Outboard electrodes cna be utilized to square up a vitrified area.

Copper-tantalum alloy

DOEpatents

Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

1986-07-15

A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

Evaluating the Field Emission Characteristics of Aluminum for DC High Voltage Photo-Electron Guns

NASA Astrophysics Data System (ADS)

Taus, Rhys; Poelker, Matthew; Forman, Eric; Mamun, Abdullah

2014-03-01

High current photoguns require high power laser light, but only a small portion of the laser light illuminating the photocathode produces electron beam. Most of the laser light (~ 65%) simply serves to heat the photocathode, which leads to evaporation of the chemicals required to create the negative electron affinity condition necessary for photoemission. Photocathode cooling techniques have been employed to address this problem, but active cooling of the photocathode is complicated because the cooling apparatus must float at high voltage. This work evaluates the field emission characteristics of cathode electrodes manufactured from materials with high thermal conductivity: aluminum and copper. These electrodes could serve as effective heat sinks, to passively cool the photocathode that resides within such a structure. However, literature suggests ``soft'' materials like aluminum and copper are ill suited for photogun applications, due to excessive field emission when biased at high voltage. This work provides an evaluation of aluminum and copper electrodes inside a high voltage field emission test stand, before and after coating with titanium nitride (TiN), a coating that enhances surface hardness. National Science Foundation Award Number: 1062320 and the Department of Defence ASSURE program.

Evaluation of Graphene/WO3 and Graphene/CeO x Structures as Electrodes for Supercapacitor Applications

NASA Astrophysics Data System (ADS)

Chaitoglou, Stefanos; Amade, Roger; Bertran, Enric

2017-12-01

The combination of graphene with transition metal oxides can result in very promising hybrid materials for use in energy storage applications thanks to its intriguing properties, i.e., highly tunable surface area, outstanding electrical conductivity, good chemical stability, and excellent mechanical behavior. In the present work, we evaluate the performance of graphene/metal oxide (WO3 and CeO x ) layered structures as potential electrodes in supercapacitor applications. Graphene layers were grown by chemical vapor deposition (CVD) on copper substrates. Single and layer-by-layer graphene stacks were fabricated combining graphene transfer techniques and metal oxides grown by magnetron sputtering. The electrochemical properties of the samples were analyzed and the results suggest an improvement in the performance of the device with the increase in the number of graphene layers. Furthermore, deposition of transition metal oxides within the stack of graphene layers further improves the areal capacitance of the device up to 4.55 mF/cm2, for the case of a three-layer stack. Such high values are interpreted as a result of the copper oxide grown between the copper substrate and the graphene layer. The electrodes present good stability for the first 850 cycles before degradation.

Development of an all-metal thick film cost effective metallization system for solar cells

NASA Technical Reports Server (NTRS)

Ross, B.; Parker, J.

1982-01-01

Electrodes made with pastes produced under the previous contract were analyzed and compared with raw materials. A needle-like structure observed on the electroded solar cell was identified as eutectic copper-silicon, a phase considered to benefit the electrical and metallurgical properties of the contact. Electrodes made from copper fluorocarbon and copper silver fluoride also contained this phase but had poor adhesion. A liquid medium, intended to provide transport during carbon fluoride decomposition was incorporated into the paste resulting in better adhesion. The product survived preliminary environmental tests. A 2 cm by 2 cm solar cell made with fluorocarbon activated copper electrodes and gave 7% AMI efficiency (without AR coating). Both silver fluoride and fluorocarbon screened paste electrodes can be produced for approximately $0.04 per watt.

Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis.

PubMed

Gan, Patrick; Foord, John S; Compton, Richard G

2015-10-01

Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur.

Polyelectrolyte-mediated assembly of copper-phthalocyanine tetrasulfonate multilayers and the subsequent production of nanoparticulate copper oxide thin films.

PubMed

Chickneyan, Zarui Sara; Briseno, Alejandro L; Shi, Xiangyang; Han, Shubo; Huang, Jiaxing; Zhou, Feimeng

2004-07-01

An approach to producing films of nanometer-sized copper oxide particulates, based on polyelectrolyte-mediated assembly of the precursor, copper(II)phthalocyanine tetrasulfonate (CPTS), is described. Multilayered CPTS and polydiallyldimethylammonium chloride (PDADMAC) were alternately assembled on different planar substrates via the layer-by-layer (LbL) procedure. The growth of CPTS multilayers was monitored by UV-visible spectrometry and quartz crystal microbalance (QCM) measurements. Both the UV-visible spectra and the QCM data showed that a fixed amount of CPTS could be attached to the substrate surface for a given adsorption cycle. Cyclic voltammograms at the CPTS/PDADMAC-covered gold electrode exhibited a decrease in peak currents with the layer number, indicating that the permeability of CPTS multilayers on the electrodes had diminished. When these CPTS multilayered films were calcined at elevated temperatures, uniform thin films composed of nanoparticulate copper oxide could be produced. Ellipsometry showed that the thickness of copper oxide nanoparticulate films could be precisely tailored by varying the thickness of CPTS multilayer films. The morphology and roughness of CPTS multilayer and copper oxide thin films were characterized by atomic force microscopy. X-ray diffraction (XRD) measurements indicated that these thin films contained both CuO and Cu2O nanoparticles. The preparation of such copper oxide thin films with the use of metal complex precursors represents a new route for the synthesis of inorganic oxide films with a controlled thickness.

In situ spectroscopic monitoring of CO2 reduction at copper oxide electrode.

PubMed

Wang, Liying; Gupta, Kalyani; Goodall, Josephine B M; Darr, Jawwad A; Holt, Katherine B

2017-04-28

Copper oxide modified electrodes were investigated as a function of applied electrode potential using in situ infrared spectroscopy and ex situ Raman and X-ray photoelectron spectroscopy. In deoxygenated KHCO 3 electrolyte bicarbonate and carbonate species were found to adsorb to the electrode during reduction and the CuO was reduced to Cu(i) or Cu(0) species. Carbonate was incorporated into the structure and the CuO starting material was not regenerated on cycling to positive potentials. In contrast, in CO 2 saturated KHCO 3 solution, surface adsorption of bicarbonate and carbonate was not observed and adsorption of a carbonato-species was observed with in situ infrared spectroscopy. This species is believed to be activated, bent CO 2 . On cycling to negative potentials, larger reduction currents were observed in the presence of CO 2 ; however, less of the charge could be attributed to the reduction of CuO. In the presence of CO 2 CuO underwent reduction to Cu 2 O and potentially Cu, with no incorporation of carbonate. Under these conditions the CuO starting material could be regenerated by cycling to positive potentials.

Copper nanowire coated carbon fibers as efficient substrates for detecting designer drugs using SERS.

PubMed

Halouzka, Vladimir; Halouzkova, Barbora; Jirovsky, David; Hemzal, Dusan; Ondra, Peter; Siranidi, Eirini; Kontos, Athanassios G; Falaras, Polycarpos; Hrbac, Jan

2017-04-01

Miniature Surface Enhanced Raman Scattering (SERS) sensors were fabricated by coating the carbon fiber microelectrodes with copper nanowires. The coating procedure, based on anodizing the copper wire in ultrapure water followed by cathodic deposition of the anode-derived material onto carbon fiber electrodes, provides a "clean" copper nanowire network. The developed miniature (10µm in diameter and 2mm in length) and nanoscopically rough SERS substrates are applicable in drug sensing, as shown by the detection and resolving of a range of seized designer drugs in trace amounts (microliter volumes of 10 -10 -10 -12 M solutions). The copper nanowire modified carbon microfiber substrates could also find further applications in biomedical and environmental sensing. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of an All-Metal Thick Film Cost Effective Metallization System for Solar Cells

NASA Technical Reports Server (NTRS)

Ross, B.

1980-01-01

Materials including copper powders, silver-fluoride, and silicon wafers were procured and copper pastes were prepared. Electrodes made with copper pastes were analyzed and compared with the raw materials. A needle-like structure was observed on the electroded solar cells, and was identified as eutectic copper-silicon by electron probe X-ray spectroscopy. The existence of this phase was thought to benefit electrical and metallurgical properties of the contact. Subsequently electrodes made from new material were also shown to contain this phase while simultaneously having poor adhesion.

Design, fabrication and performance of small, graphite electrode, multistage depressed collectors with 200-W, CW, 8- to 18-GHz traveling-wave tubes

NASA Technical Reports Server (NTRS)

Ebihara, Ben T.; Ramins, Peter

1987-01-01

Small multistage depressed collectors (MDC's) which used pyrolytic graphite, ion-beam-textured pyrolytic graphite, and isotropic graphite electrodes were designed, fabricated, and evaluated in conjuntion with 200-W, continuous wave (CW), 8- to 18-GHz traveling-wave tubes (TWT's). The design, construction, and performance of the MDC's are described. The bakeout performance of the collectors, in terms of gas evolution, was indistinguishable from that of typical production tubes with copper collectors. However, preliminary results indicate that some additional radiofrequency (RF) and dc beam processing time (and/or longer or higher temperature bakeouts) may be needed beyond that of typical copper electrode collectors. This is particularly true for pyrolytic graphite electrodes and for TWT's without appendage ion pumps. Extended testing indicated good long-term stability of the textured pyrolytic graphite and isotropic graphite electrode surfaces. The isotropic graphite in particular showed considerable promise as an MDC electrode material because of its high purity, low cost, simple construction, potential for very compact overall size, and relatively low secondary electron emission yield characteristics in the as-machined state. However, considerably more testing experience is required before definitive conclusions on its suitability for electronic countermeasure systems and space TWT's can be made.

Tantalum-copper alloy and method for making

DOEpatents

Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

1984-11-06

A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

Tantalum-copper alloy and method for making

DOEpatents

Schmidt, F.A.; Verhoeven, J.D.; Gibson, E.D.

1983-06-01

A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

Letter: Entrapment and interaction of an air bubble with an oscillating cavitation bubble

NASA Astrophysics Data System (ADS)

Kannan, Y. S.; Karri, Badarinath; Sahu, Kirti Chandra

2018-04-01

The mechanism of the formation of an air bubble due to an oscillating cavitation bubble in its vicinity is reported from an experimental study using high-speed imaging. The cavitation bubble is created close to the free surface of water using a low-voltage spark circuit comprising two copper electrodes in contact with each other. Before the bubble is created, a third copper wire is positioned in contact with the free surface of water close to the two crossing electrodes. Due to the surface tension at the triple point (wire-water-air) interface, a small dip is observed in the free surface at the point where the wire is immersed. When the cavitation bubble is created, the bubble pushes at the dip while expanding and pulls at it while collapsing. The collapse phase leads to the entrapment of an air bubble at the wire immersion point. During this phase, the air bubble undergoes a "catapult" effect, i.e., it expands to a maximum size and then collapses with a microjet at the free surface. To the best of our knowledge, this mechanism has not been reported so far. A parametric study is also conducted to understand the effects of wire orientation and bubble distance from the free surface.

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.

Polypyrrole Coated Cellulosic Substrate Modified by Copper Oxide as Electrode for Nitrate Electroreduction

NASA Astrophysics Data System (ADS)

Hamam, A.; Oukil, D.; Dib, A.; Hammache, H.; Makhloufi, L.; Saidani, B.

2015-08-01

The aim of this work is to synthesize polypyrrole (PPy) films on nonconducting cellulosic substrate and modified by copper oxide particles for use in the nitrate electroreduction process. Firstly, the chemical polymerization of polypyrrole onto cellulosic substrate is conducted by using FeCl3 as an oxidant and pyrrole as monomer. The thickness and topography of the different PPy films obtained were estimated using a profilometer apparatus. The electrochemical reactivity of the obtained electrodes was tested by voltamperometry technique and electrochemical impedance spectroscopy. Secondly, the modification of the PPy film surface by incorporation of copper oxide particles is conducted by applying a galvanostatic procedure from a CuCl2 solution. The SEM, EDX and XRD analysis showed the presence of CuO particles in the polymer films with dimensions less than 50 nm. From cyclic voltamperometry experiments, the composite activity for the nitrate electroreduction reaction was evaluated and the peak of nitrate reduction is found to vary linearly with initial nitrate concentration.

Copper oxide assisted cysteine hierarchical structures for immunosensor application

NASA Astrophysics Data System (ADS)

Pandey, Chandra Mouli; Sumana, Gajjala; Tiwari, Ida

2014-09-01

The present work describes the promising electrochemical immunosensing strategy based on copper (II) assisted hierarchical cysteine structures (CuCys) varying from star to flower like morphology. The CuCys having average size of 10 μm have been synthesised using L-Cysteine as initial precursor in presence of copper oxide under environmentally friendly conditions in aqueous medium. To delineate the synthesis mechanism, detailed structural investigations have been carried out using characterization techniques such as X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The electrochemical behaviour of self-assembled CuCys on gold electrode shows surface controlled electrode reaction with an apparent electron transfer rate constant of 3.38 × 10-4 cm s-1. This innovative platform has been utilized to fabricate an immunosensor by covalently immobilizing monoclonal antibodies specific for Escherichia coli O157:H7 (E. coli). Under the optimal conditions, the fabricated immunosensor is found to be sensitive and specific for the detection of E. coli with a detection limit of 10 cfu/ml.

Fabrication of copper-based anodes via atmosphoric plasma spraying techniques

DOEpatents

Lu, Chun [Monroeville, PA

2012-04-24

A fuel electrode anode (18) for a solid oxide fuel cell is made by presenting a solid oxide fuel cell having an electrolyte surface (15), mixing copper powder with solid oxide electrolyte in a mixing step (24, 44) to provide a spray feedstock (30,50) which is fed into a plasma jet (32, 52) of a plasma torch to melt the spray feed stock and propel it onto an electrolyte surface (34, 54) where the spray feed stock flattens into lamellae layer upon solidification, where the layer (38, 59) is an anode coating with greater than 35 vol. % based on solids volume.

Method of forming components for a high-temperature secondary electrochemical cell

DOEpatents

Mrazek, Franklin C.; Battles, James E.

1983-01-01

A method of forming a component for a high-temperature secondary electrochemical cell having a positive electrode including a sulfide selected from the group consisting of iron sulfides, nickel sulfides, copper sulfides and cobalt sulfides, a negative electrode including an alloy of aluminum and an electrically insulating porous separator between said electrodes. The improvement comprises forming a slurry of solid particles dispersed in a liquid electrolyte such as the lithium chloride-potassium chloride eutetic, casting the slurry into a form having the shape of one of the components and smoothing the exposed surface of the slurry, cooling the cast slurry to form the solid component, and removing same. Electrodes and separators can be thus formed.

Glow discharge cleaning of vacuum switch tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayashi, T.; Toya, H.

1991-10-01

This paper reports that glow discharge cleaning has ben advancing as a means of degassing vacuum chambers constructed for a large accelerator or for nuclear fusion research. To clean the whole surface of parts inside a vacuum switch tube (VST), a new technique is tried which generates glow discharge between the inner electrodes and copper grid surrounding it. Photographic observation reveals that the glow discharge spreads out and cleans the whole surface inside the VST. A breakdown test between the inner electrodes shows the effect of the cleaning with this technique. Higher breakdown voltage between the inner electrodes is attainedmore » by performing this glow discharge cleaning in argon rather than hydrogen gas. The difference of the cleaning effect seems to be attributed to that of the energy transfer from ion species to the absorbed molecules and microprotrusions on the surfaces.« less

Study of a DC gas discharge with a copper cathode in a water flow

NASA Astrophysics Data System (ADS)

Tazmeev, G. Kh.; Timerkaev, B. A.; Tazmeev, Kh. K.

2017-07-01

A dc gas discharge between copper electrodes in the current range of 5-20 A was studied experimentally. The discharge gap length was varied within 45-70 mm. The cathode was a 10-mm-diameter rod placed in the water flowing out from a dielectric tube. Three discharge configurations differing in the position of the cathode upper end with respect to the water surface were considered: (i) above water; (ii) flush with the water surface, and (iii) under water. The electric and optical characteristics of the discharge in the second configuration were studied in more detail. It is established that the discharge properties are similar to those of an electric arc. Considerable cathode erosion was observed in the third configuration. It is revealed that fine-dispersed copper grains form in the course of erosion.

Electrochemical CO 2 Reduction on Oxide-Derived Cu Surface with Various Oxide Thicknesses

DOE PAGES

Liang, Zhixiu; Fu, Jie; Vukmirovic, Miomir B.; ...

2018-03-26

Here, cuprous oxide on copper foil electrodes prepared via electrochemical deposition and thermal annealing are investigated towards CO 2 electrochemical reduction at low overpotential. The thickness of the electrochemical deposited Cu 2O was controlled by varying the constant-current deposition time. The surface morphology and roughness were examined with SEM and CV respectively. The electrode fabricated by cuprous oxide deposited for 20 min demonstrated the best faradic efficiency (7.02%) and specific activity (0.123 mA/cm 2) towards format/formic acid formation at -0.5 V vs. RHE in CO 2 saturated 0.5 M K 2CO 3 among studied samples.

Electrochemical CO 2 Reduction on Oxide-Derived Cu Surface with Various Oxide Thicknesses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Zhixiu; Fu, Jie; Vukmirovic, Miomir B.

Here, cuprous oxide on copper foil electrodes prepared via electrochemical deposition and thermal annealing are investigated towards CO 2 electrochemical reduction at low overpotential. The thickness of the electrochemical deposited Cu 2O was controlled by varying the constant-current deposition time. The surface morphology and roughness were examined with SEM and CV respectively. The electrode fabricated by cuprous oxide deposited for 20 min demonstrated the best faradic efficiency (7.02%) and specific activity (0.123 mA/cm 2) towards format/formic acid formation at -0.5 V vs. RHE in CO 2 saturated 0.5 M K 2CO 3 among studied samples.

Cold cap subsidence for in situ vitrification and electrodes therefor

DOEpatents

Buelt, James L.; Carter, John G.; Eschbach, Eugene A.; FitzPatrick, Vincent F.; Koehmstedt, Paul L.; Morgan, William C.; Oma, Kenton H.; Timmerman, Craig L.

1992-01-01

An electrode for use in in situ vitrification of soil comprises a molybdenum rod received within a conductive sleeve or collar formed of graphite. Electrodes of this type are placed on either side of a region containing buried waste material and an electric current is passed therebetween for vitrifying the soil between the electrodes. The graphite collar enhances the thermal conductivity of the electrode, bringing heat to the surface, and preventing the formation of a cold cap of material above the ground surface. The annulus between the molybdenum rod electrode and the graphite collar is filled with a conductive ceramic powder of a type that sinters upon the molybdenum rod, protecting the same from oxidation as the graphite material is consumed, or a metal powder which liquifies at operating temperatures. The molybdenum rod in the former case may be coated with an oxidation protectant, e.g. of molybdenum disilicide. As insulative blanket is suitably placed on the surface of the soil during processing to promote subsidence by allowing off-gassing and reducing surface heat loss. In other embodiments, connection to vitrification electrodes is provided below ground level to avoid loss of connection due to electrodes deterioration, or a sacrificial electrode may be employed when operation is started. Outboard electrodes can be utilized to square up the vitrified area. Further, the center of the molybdenum rod can be made hollow and filled with a powdered metal, such as copper, which liquifies at operating temperatures. In one embodiment, the molybdenum rod and the graphite collar are physically joined at the bottom.

High rate copper and energy recovery in microbial fuel cells

PubMed Central

Rodenas Motos, Pau; ter Heijne, Annemiek; van der Weijden, Renata; Saakes, Michel; Buisman, Cees J. N.; Sleutels, Tom H. J. A.

2015-01-01

Bioelectrochemical systems (BESs) are a novel, promising technology for the recovery of metals. The prerequisite for upscaling from laboratory to industrial size is that high current and high power densities can be produced. In this study we report the recovery of copper from a copper sulfate stream (2 g L-1 Cu2+) using a laboratory scale BES at high rate. To achieve this, we used a novel cell configuration to reduce the internal voltage losses of the system. At the anode, electroactive microorganisms produce electrons at the surface of an electrode, which generates a stable cell voltage of 485 mV when combined with a cathode where copper is reduced. In this system, a maximum current density of 23 A m-2 in combination with a power density of 5.5 W m-2 was produced. XRD analysis confirmed 99% purity in copper of copper deposited onto cathode surface. Analysis of voltage losses showed that at the highest current, most voltage losses occurred at the cathode, and membrane, while anode losses had the lowest contribution to the total voltage loss. These results encourage further development of BESs for bioelectrochemical metal recovery. PMID:26150802

Electrostatic atomization: Effect of electrode materials on electrostatic atomizer performance

NASA Astrophysics Data System (ADS)

Sankaran, Abhilash; Staszel, Christopher; Kashir, Babak; Perri, Anthony; Mashayek, Farzad; Yarin, Alexander

2016-11-01

Electrostatic atomization was studied experimentally with a pointed electrode in a converging nozzle. Experiments were carried out on poorly conductive canola oil where it was observed that electrode material may affect charge transfer. This points at the possible faradaic reactions that can occur at the surfaces of the electrodes. The supply voltage is applied to the sharp electrode and the grounded nozzle body constitutes the counter-electrode. The charge transfer is controlled by the electrochemical reactions on both the electrodes. The electrical performance study of the atomizer issuing a charged oil jet was conducted using three different nozzle body materials - brass, copper and stainless steel. Also, two sharp electrode materials - brass and stainless steel - were tested. The experimental results revealed that both the nozzle body material, as well as the sharp electrode material affected the spray and leak currents. Moreover, the effect of the sharp electrode material is quite significant. This research is supported by NSF Grant 1505276.

Effect of anode material on the breakdown in low-pressure helium gas

NASA Astrophysics Data System (ADS)

Demidov, V. I.; Adams, S. F.; Kudryavtsev, A. A.; Kurlyandskaya, I. P.; Miles, J. A.; Tolson, B. A.

2017-10-01

The electric breakdown of gases is one of the fundamental phenomena of gas discharge physics. It has been studied for a long time but still attracts incessant interest of researchers. Besides the interesting physics, breakdown is important for many applications including development of reliable electric insulation in electric grids and the study of different aspects of gas discharge physics. In this work an experimental study of the electric breakdown in helium gas for the plane-parallel electrode configuration has been conducted using a copper cathode and a variety of anode materials: copper, aluminum, stainless steel, graphite, platinum-plated aluminum and gold-plated aluminum. According to the Paschen law for studied electrode configuration, the breakdown voltage is a function of the product of gas pressure and inter-electrode gap. The breakdown processes on the left, lower pressure side of the Paschen curve have been the subject of this investigation. For those pressures, the Paschen curve may become multi-valued, where any given pressure corresponds to three breakdown voltage values. It was experimentally demonstrated that the form of the Paschen curve might strongly depend on the material of the anode and the cleanness of the anode surface. A possible explanation for this phenomenon is that electrons streaming from the cathode are reflected by the surface of the anode.

Effects of copper vapour on thermophysical properties of CO2-N2 plasma

NASA Astrophysics Data System (ADS)

Zhong, Linlin; Wang, Xiaohua; Rong, Mingzhe; Cressault, Yann

2016-10-01

CO2-N2 mixtures are often used as arc quenching medium (to replace SF6) in circuit breakers and shielding gas in arc welding. In such applications, copper vapour resulting from electrode surfaces can modify characteristics of plasmas. This paper therefore presents an investigation of the effects of copper on thermophysical properties of CO2-N2 plasma. The equilibrium compositions, thermodynamic properties (including mass density, specific enthalpy, and specific heat), transport coefficients (including electrical conductivity, viscosity, and thermal conductivity), and four kinds of combined diffusion coefficients due to composition gradients, applied electric fields, temperature gradients, and pressure gradients respectively, were calculated and discussed for CO2-N2 (mixing ratio 7:3) plasma contaminated by different proportions of copper vapour. The significant influences of copper were observed on all the properties of CO2-N2-Cu mixtures. The better ionization ability and larger molar mass of copper and larger collision integrals related to copper, should be responsible for such influences.

Modeling dioxygen reduction at multicopper oxidase cathodes.

PubMed

Agbo, Peter; Heath, James R; Gray, Harry B

2014-10-01

We report a general kinetics model for catalytic dioxygen reduction on multicopper oxidase (MCO) cathodes. Our rate equation combines Butler-Volmer (BV) electrode kinetics and the Michaelis-Menten (MM) formalism for enzymatic catalysis, with the BV model accounting for interfacial electron transfer (ET) between the electrode surface and the MCO type 1 copper site. Extending the principles of MM kinetics to this system produced an analytical expression incorporating the effects of subsequent intramolecular ET and dioxygen binding to the trinuclear copper cluster into the cumulative model. We employed experimental electrochemical data on Thermus thermophilus laccase as benchmarks to validate our model, which we suggest will aid in the design of more efficient MCO cathodes. In addition, we demonstrate the model's utility in determining estimates for both the electronic coupling and average distance between the laccase type-1 active site and the cathode substrate.

Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis

PubMed Central

Gan, Patrick; Foord, John S; Compton, Richard G

2015-01-01

Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur. PMID:26491640

Horseradish peroxidase immobilized on copper surfaces and applications in selective electrocatalysis of p-dihydroxybenzene

NASA Astrophysics Data System (ADS)

Wang, Chuntao; Luo, Xiaoxiao; Jia, Zehui; Shi, Qinghua; Zhu, Ritao

2017-06-01

Horseradish Peroxidase (HRP) was immobilized on copper surfaces with the linker of L-Cysteine (L-Cys) self-assembled films to form Cu/L-Cys/HRP electrodes. The activity of HRP can be preserved by the Cu/L-Cys self-assembled films. The Cu/L-Cys/HRP electrodes can be used for the selective electrocatalytic oxidase of p-dihydroxybenzen in absent of H2O2. The optimum pH for electrocatalyzing p-dihydroxybenzen was 5.5 or 7.0, which corresponds to the isoelectric points of L-Cys and HRP, respectively. X-ray photoelectron spectroscopy (XPS) provided the evidence that L-Cys linked with Cu surface by the Cusbnd S bond. Fourier transform infrared spectroscopy (FTIR) analyses indicated that aromatic plane of p-dihydroxybenzen was connected parallel to porphyrin ring of heme in HRP. Quantum chemical calculation of density functional theory (DFT) revealed that symmetry of molecular structure and minimum space steric hindrance for p-dihydroxybenzen were benefit to combination with HRP. Moreover, the lowest energy of LUMO and most negative charges of oxygen atom on hydroxyl group of p-dihydroxybenzen were advantage to lose the hydrogen atom of hydroxyl group to be oxided.

Study on monatomic fraction improvement with alumina layer on metal electrode in hydrogen plasma ion source.

PubMed

Jung, Bong-Ki; Chung, Kyoung-Jae; Dang, Jeong-Jeung; Hwang, Y S

2012-02-01

A high monatomic beam fraction is an important factor in a hydrogen ion source to increase the application efficiency. The monatomic fraction of hydrogen plasmas with different plasma electrode materials is measured in a helicon plasma ion source, and aluminum shows the highest value compared to that with the other metals such as copper and molybdenum. Formation of an aluminum oxide layer on the aluminum electrode is determined by XPS analysis, and the alumina layer is verified as the high monatomic fraction. Both experiments and numerical simulations conclude that a low surface recombination coefficient of the alumina layer on the plasma electrode is one of the most important parameters for increasing the monatomic fraction in hydrogen plasma ion sources.

Study on monatomic fraction improvement with alumina layer on metal electrode in hydrogen plasma ion sourcea)

NASA Astrophysics Data System (ADS)

Jung, Bong-Ki; Chung, Kyoung-Jae; Dang, Jeong-Jeung; Hwang, Y. S.

2012-02-01

A high monatomic beam fraction is an important factor in a hydrogen ion source to increase the application efficiency. The monatomic fraction of hydrogen plasmas with different plasma electrode materials is measured in a helicon plasma ion source, and aluminum shows the highest value compared to that with the other metals such as copper and molybdenum. Formation of an aluminum oxide layer on the aluminum electrode is determined by XPS analysis, and the alumina layer is verified as the high monatomic fraction. Both experiments and numerical simulations conclude that a low surface recombination coefficient of the alumina layer on the plasma electrode is one of the most important parameters for increasing the monatomic fraction in hydrogen plasma ion sources.

Method of forming components for a high-temperature secondary electrochemical cell

DOEpatents

Mrazek, F.C.; Battles, J.E.

1981-05-22

A method of forming a component for a high-temperature secondary electrochemical cell having a positive electrode including a sulfide selected from the group consisting of iron sulfides, nickel sulfides, copper sulfides and cobalt sulfides, a negative electrode including an alloy of aluminum and an electrically insulating porous separator between said electrodes is described. The improvement comprises forming a slurry of solid particles dispersed in a liquid electrolyte such as the lithium chloride-potassium chloride eutectic, casting the slurry into a form having the shape of one of the components and smoothing the exposed surface of the slurry, cooling the cast slurry to form the solid component, and removing same. Electrodes and separators can be thus formed.

Organic solar cells with graphene electrodes and vapor printed poly(3,4-ethylenedioxythiophene) as the hole transporting layers.

PubMed

Park, Hyesung; Howden, Rachel M; Barr, Miles C; Bulović, Vladimir; Gleason, Karen; Kong, Jing

2012-07-24

For the successful integration of graphene as a transparent conducting electrode in organic solar cells, proper energy level alignment at the interface between the graphene and the adjacent organic layer is critical. The role of a hole transporting layer (HTL) thus becomes more significant due to the generally lower work function of graphene compared to ITO. A commonly used HTL material with ITO anodes is poly(3,4-ethylenedioxythiophene) (PEDOT) with poly(styrenesulfonate) (PSS) as the solid-state dopant. However, graphene's hydrophobic surface renders uniform coverage of PEDOT:PSS (aqueous solution) by spin-casting very challenging. Here, we introduce a novel, yet simple, vapor printing method for creating patterned HTL PEDOT layers directly onto the graphene surface. Vapor printing represents the implementation of shadow masking in combination with oxidative chemical vapor deposition (oCVD). The oCVD method was developed for the formation of blanket (i.e., unpatterened) layers of pure PEDOT (i.e., no PSS) with systematically variable work function. In the unmasked regions, vapor printing produces complete, uniform, smooth layers of pure PEDOT over graphene. Graphene electrodes were synthesized under low-pressure chemical vapor deposition (LPCVD) using a copper catalyst. The use of another electron donor material, tetraphenyldibenzoperiflanthene, instead of copper phthalocyanine in the organic solar cells also improves the power conversion efficiency. With the vapor printed HTL, the devices using graphene electrodes yield comparable performances to the ITO reference devices (η(p,LPCVD) = 3.01%, and η(p,ITO) = 3.20%).

Laser-Assisted Reduction of Highly Conductive Circuits Based on Copper Nitrate for Flexible Printed Sensors

NASA Astrophysics Data System (ADS)

Bai, Shi; Zhang, Shigang; Zhou, Weiping; Ma, Delong; Ma, Ying; Joshi, Pooran; Hu, Anming

2017-10-01

Stretchable electronic sensing devices are defining the path toward wearable electronics. High-performance flexible strain sensors attached on clothing or human skin are required for potential applications in the entertainment, health monitoring, and medical care sectors. In this work, conducting copper electrodes were fabricated on polydimethylsiloxane as sensitive stretchable microsensors by integrating laser direct writing and transfer printing approaches. The copper electrode was reduced from copper salt using laser writing rather than the general approach of printing with pre-synthesized copper or copper oxide nanoparticles. An electrical resistivity of 96 μΩ cm was achieved on 40-μm-thick Cu electrodes on flexible substrates. The motion sensing functionality successfully demonstrated a high sensitivity and mechanical robustness. This in situ fabrication method leads to a path toward electronic devices on flexible substrates.[Figure not available: see fulltext.

Surface Studies Of Dielectric Materials Used In Spark Gaps

DTIC Science & Technology

1983-06-01

on the virgin sample shows 78.1% carbon, 11.5’% oxygen, 5.2% nitrogen and 5.2% silicon . The usual composition of nylon is C6H110N which would give...copper composite ) electrodes. The spark gap selfbreaks at 40-45kV and switches approximately 1 kJ of energy in 2 ~s at a maximum rep-rate of 2... composite , two different tungsten- copper composites (K-33 and Elkonite), or stainless steel. The spark gap normally operates at a voltage of less than

Growth of copper phthalocyanine rods on Au plasmon electrodes through micelle disruption methods.

PubMed

Chen, Wei-Hung; Ko, Wen-Yin; Chen, Ying-Shiou; Cheng, Ching-Yuan; Chan, Chi-Ming; Lin, Kuan-Jiuh

2010-02-16

To improve the efficiency of the photocurrent conversion process, we have utilized copper phthalocyanine (CuPc) rods, which are capable of enhancing the interfacial area of electron transport and plasmonic gold nanoparticles (Au NPs), which can increase the separation and photogeneration of excitons, to produce a more effective system. In-plane horizontal CuPc rods, with diameters ranging from 0.2 to 1.5 microm, were electrodeposited onto the surface of plasmonic (Au NP) monolayers predeposited onto ITO substrates through electrolytic micelle disruption (EMD) methods.

Palladium Coated Copper Nanowires as a Hydrogen Oxidation Electrocatalyst in Base

DOE PAGES

Alia, Shaun M.; Yan, Yushan

2015-05-09

The palladium (Pd) nanotubes we synthesized by the spontaneous galvanic displacement of copper (Cu) nanowires, are forming extended surface nanostructures highly active for the hydrogen oxidation reaction (HOR) in base. The synthesized catalysts produce specific activities in rotating disk electrode half-cells 20 times greater than Pd nanoparticles and about 80% higher than polycrystalline Pd. Although the surface area of the Pd nanotubes was low compared to conventional catalysts, partial galvanic displacement thrifted the noble metal layer and increased the Pd surface area. Moreover, the use of Pd coated Cu nanowires resulted in a HOR mass exchange current density 7 timesmore » greater than the Pd nanoparticles. The activity of the Pd coated Cu nanowires further nears Pt/C, producing 95% of the mass activity.« less

Visual Observation of Dissolution of Copper Ions from a Copper Electrode

ERIC Educational Resources Information Center

Ikemoto, Isao; Saitou, Kouichi

2013-01-01

During electrolysis, to visually observe the conversion of a metal to its cation, either the cation or its complex ion should have a distinct color while the electrolyte solution must be colorless and transparent. A demonstration is described in which copper is used as the electrodes and sodium polyacrylate (a superabsorbent polymer) solution is…

Removal of copper in leachate from mining residues using electrochemical technology.

PubMed

Lambert, Andréa; Drogui, Patrick; Daghrir, Rimeh; Zaviska, François; Benzaazoua, Mostafa

2014-01-15

This research is related to a laboratory study on the performance of a successive mining residues leaching and electrochemical copper recovery process. To clearly define the experimental region for response surface methodology (RSM), a preliminary study was performed by applying a current intensity varying from 0.5 A to 4.0 A for 60 min. By decreasing the current intensity from 4.0 A to 0.5 A, a good adhesion and a very smooth and continuous interface of copper was formed and deposited on the cathode electrode. However, the removal rate of Cu decreased from 83.7% to 37.9% when the current intensity passed from 4.0 A to 0.5 A, respectively. Subsequently, the factorial design and central composite design methodologies were successively employed to define the optimal operating conditions for copper removal in the mining residues leachate. Using a 2(3) factorial matrix, the best performance for copper removal (97.7%) was obtained at a current intensity of 2.0 A during 100 min. The current intensity and electrolysis time were found to be the most influent parameters. The contribution of current intensity and electrolysis time was around 65.8% and 33.9%, respectively. The treatment using copper electrode and current intensity of 1.3 A during 80 min was found to be the optimal conditions in terms of cost/effectiveness. Under these conditions, 86% of copper can be recovered for a total cost of 0.56 $ per cubic meter of treated mining residues leachate. Copyright © 2013 Elsevier Ltd. All rights reserved.

Surface loss probability of atomic hydrogen for different electrode cover materials investigated in H₂-Ar low-pressure plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sode, M., E-mail: maik.sode@ipp.mpg.de; Schwarz-Selinger, T.; Jacob, W.

2014-07-07

In an inductively coupled H₂-Ar plasma at a total pressure of 1.5 Pa, the influence of the electrode cover material on selected line intensities of H, H₂, and Ar are determined by optical emission spectroscopy and actinometry for the electrode cover materials stainless steel, copper, tungsten, Macor{sup ®}, and aluminum. Hydrogen dissociation degrees for the considered conditions are determined experimentally from the measured emission intensity ratios. The surface loss probability β{sub H} of atomic hydrogen is correlated with the measured line intensities, and β{sub H} values are determined for the considered materials. Without the knowledge of the atomic hydrogen temperature,more » β{sub H} cannot be determined exactly. However, ratios of β{sub H} values for different surface materials are in first order approximation independent of the atomic hydrogen temperature. Our results show that β{sub H} of copper is equal to the value of stainless steel, β{sub H} of Macor{sup ®} and tungsten is about 2 times smaller and β{sub H} of aluminum about 5 times smaller compared with stainless steel. The latter ratio is in reasonable agreement with literature. The influence of the atomic hydrogen temperature T{sub H} on the absolute value is thoroughly discussed. For our assumption of T{sub H}=600 K, we determine a β{sub H} for stainless steel of 0.39±0.13.« less

Copper-phospholipid interaction at cell membrane model hydrophobic surfaces.

PubMed

Mlakar, Marina; Cuculić, Vlado; Frka, Sanja; Gašparović, Blaženka

2018-04-01

Detailed investigation of Cu (II) binding with natural lipid phosphatidylglycerol (PG) in aqueous solution was carried out by voltammetric measurements at the mercury drop electrode, complemented by monolayer studies in a Langmuir trough and electrophoretic measurements, all used as models for hydrophobic cell membranes. Penetration of copper ions into the PG layer was facilitated by the formation of hydrophilic Cu-Phenanthroline (Phen) complex in the subphase, followed by the mixed ligand Cu-Phen-PG complex formation at the hydrophobic interface. Electrophoretic measurements indicated a comparatively low abundance of the formed mixed ligand complex within the PG vesicles, resulting it the zeta potential change of +0.83mV, while monolayer studies confirmed their co-existence at the interface. The Cu-Phen-PG complex was identified in the pH range from 6 to 9. The stoichiometry of the complex ([PhenCuOHPG]), as well as its stability and kinetics of formation, were determined at the mercury drop electrode. Cu-Phen-PG reduces quasireversibly at about -0.7V vs. Ag/AgCl including reactant adsorption, followed by irreversible mixed complex dissociation, indicating a two-electron transfer - chemical reaction (EC mechanism). Consequently, the surface concentration (γ) of the adsorbed [PhenCuOHPG] complex at the hydrophobic electrode surface was calculated to be (3.35±0.67)×10 -11 molcm -2 . Information on the mechanism of Cu (II) - lipid complex formation is a significant contribution to the understanding of complex processes at natural cell membranes. Copyright © 2017 Elsevier B.V. All rights reserved.

Copper oxide assisted cysteine hierarchical structures for immunosensor application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pandey, Chandra Mouli; Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005; Sumana, Gajjala, E-mail: sumanagajjala@gmail.com

2014-09-08

The present work describes the promising electrochemical immunosensing strategy based on copper (II) assisted hierarchical cysteine structures (CuCys) varying from star to flower like morphology. The CuCys having average size of 10 μm have been synthesised using L-Cysteine as initial precursor in presence of copper oxide under environmentally friendly conditions in aqueous medium. To delineate the synthesis mechanism, detailed structural investigations have been carried out using characterization techniques such as X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The electrochemical behaviour of self-assembled CuCys on gold electrode shows surface controlled electrode reaction with an apparent electron transfer rate constantmore » of 3.38 × 10{sup −4 }cm s{sup −1}. This innovative platform has been utilized to fabricate an immunosensor by covalently immobilizing monoclonal antibodies specific for Escherichia coli O157:H7 (E. coli). Under the optimal conditions, the fabricated immunosensor is found to be sensitive and specific for the detection of E. coli with a detection limit of 10 cfu/ml.« less

Effects of pulse ON and OFF time and electrode types on the material removal rate and tool wear rate of the Ti-6Al-4V Alloy using EDM machining with reverse polarity

NASA Astrophysics Data System (ADS)

Praveen, L.; Geeta Krishna, P.; Venugopal, L.; Prasad, N. E. C.

2018-03-01

Electrical Discharge Machining (EDM) is an unconventional metal removal process that is extensively used for removing the difficult-to-machine metal such as Ti alloys, super alloys and metal matrix composites. This paper investigates the effects of pulse (ON/OFF) time on EDM machining characteristics of Ti-6Al-4V alloy using copper and graphite as electrodes in reverse polarity condition. Full factorial design method was used to design the experiments. Two variables (Pulse On and OFF) with three levels are considered. The output variables are the tool wear rate and the material removal rate. The important findings from the present work are: (1) the material removal rate (MRR) increases gradually with an increase of the Pulse ON time whereas the change is insignificant with an increase of the Pulse OFF time, (2) Between copper and graphite electrodes, the copper electrode is proved to be good in terms of MRR, (3) a combination of high pulse ON time and OFF time is desirable for high MRR rate in the Cu electrode whereas for the graphite electrode, a combination of high pulse ON time and low pulse OFF time is desirable for high MRR rate, (4) the tool wear rate (TWR) reduces with the Pulse On or OFF time, the rate of TWR is uniform for the graphite electrode in contrast to abrupt decrease from 25 to 50 μs (pulse ON time) in the copper electrode, (5) In order to keep the TWR as minimum possible, it is desirable to have a combination of high pulse ON time and OFF time for both the copper and the graphite electrode.

Preparation of the spacer for narrow electrode gap configuration in ionization-based gas sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saheed, Mohamed Shuaib Mohamed; Mohamed, Norani Muti; Burhanudin, Zainal Arif

2012-09-26

Carbon nanotubes (CNTs) have started to be developed as the sensing element for ionization-based gas sensors due to the demand for improved sensitivity, selectivity, stability and other sensing properties beyond what can be offered by the conventional ones. Although these limitations have been overcome, the problems still remain with the conventional ionization-based gas sensors in that they are bulky and operating with large breakdown voltage and high temperature. Recent studies have shown that the breakdown voltage can be reduced by using nanostructured electrodes and narrow electrode gap. Nanostructured electrode in the form of aligned CNTs array with evenly distributed nanotipsmore » can enhance the linear electric field significantly. The later is attributed to the shorter conductivity path through narrow electrode gap. The paper presents the study on the design consideration in order to realize ionization based gas sensor using aligned carbon nanotubes array in an optimum sensor configuration with narrow electrode gap. Several deposition techniques were studied to deposit the spacer, the key component that can control the electrode gap. Plasma spray deposition, electron beam deposition and dry oxidation method were employed to obtain minimum film thickness around 32 {mu}m. For plasma spray method, sand blasting process is required in order to produce rough surface for strong bonding of the deposited film onto the surface. Film thickness, typically about 39 {mu}m can be obtained. For the electron beam deposition and dry oxidation, the film thickness is in the range of nanometers and thus unsuitable to produce the spacer. The deposited multilayer film consisting of copper, alumina and ferum on which CNTs array will be grown was found to be removed during the etching process. This is attributed to the high etching rate on the thin film which can be prevented by reducing the rate and having a thicker conductive copper film.« less

Analytical application of solid contact ion-selective electrodes for determination of copper and nitrate in various food products and drinking water.

PubMed

Wardak, Cecylia; Grabarczyk, Malgorzata

2016-08-02

A simple, fast and cheap method for monitoring copper and nitrate in drinking water and food products using newly developed solid contact ion-selective electrodes is proposed. Determination of copper and nitrate was performed by application of multiple standard additions technique. The reliability of the obtained results was assessed by comparing them using the anodic stripping voltammetry or spectrophotometry for the same samples. In each case, satisfactory agreement of the results was obtained, which confirms the analytical usefulness of the constructed electrodes.

Autonomous colloidal crystallization in a galvanic microreactor

NASA Astrophysics Data System (ADS)

Punckt, Christian; Jan, Linda; Jiang, Peng; Frewen, Thomas A.; Saville, Dudley A.; Kevrekidis, Ioannis G.; Aksay, Ilhan A.

2012-10-01

We report on a technique that utilizes an array of galvanic microreactors to guide the assembly of two-dimensional colloidal crystals with spatial and orientational order. Our system is comprised of an array of copper and gold electrodes in a coplanar arrangement, immersed in a dilute hydrochloric acid solution in which colloidal micro-spheres of polystyrene and silica are suspended. Under optimized conditions, two-dimensional colloidal crystals form at the anodic copper with patterns and crystal orientation governed by the electrode geometry. After the aggregation process, the colloidal particles are cemented to the substrate by co-deposition of reaction products. As we vary the electrode geometry, the dissolution rate of the copper electrodes is altered. This way, we control the colloidal motion as well as the degree of reaction product formation. We show that particle motion is governed by a combination of electrokinetic effects acting directly on the colloidal particles and bulk electrolyte flow generated at the copper-gold interface.

Controllably annealed CuO-nanoparticle modified ITO electrodes: Characterisation and electrochemical studies

NASA Astrophysics Data System (ADS)

Wang, Tong; Su, Wen; Fu, Yingyi; Hu, Jingbo

2016-12-01

In this paper, we report a facile and controllable two-step approach to produce indium tin oxide electrodes modified by copper(II) oxide nanoparticles (CuO/ITO) through ion implantation and annealing methods. After annealing treatment, the surface morphology of the CuO/ITO substrate changed remarkably and exhibited highly electroactive sites and a high specific surface area. The effects of annealing treatment on the synthesis of CuO/ITO were discussed based on various instruments' characterisations, and the possible mechanism by which CuO nanoparticles were generated was also proposed in this work. Cyclic voltammetric results indicated that CuO/ITO electrodes exhibited effective catalytic responses toward glucose in alkaline solution. Under optimal experimental conditions, the proposed CuO/ITO electrode showed sensitivity of 450.2 μA cm-2 mM-1 with a linear range of up to ∼4.4 mM and a detection limit of 0.7 μM (S/N = 3). Moreover, CuO/ITO exhibited good poison resistance, reproducibility, and stability properties.

Optimization of electrochemical dechlorination of trichloroethylene in reducing electrolytes

PubMed Central

Mao, Xuhui; Ciblak, Ali; Baek, Kitae; Amiri, Mohammad; Loch-Caruso, Rita; Alshawabkeh, Akram N.

2012-01-01

Electrochemical dechlorination of trichloroethylene (TCE) in aqueous solution is investigated in a closed, liquid-recirculation system. The anodic reaction of cast iron generates ferrous species, creating a chemically reducing electrolyte (negative ORP value). The reduction of TCE on the cathode surface is enhanced under this reducing electrolyte because of the absence of electron competition. In the presence of the iron anode, the performances of different cathodes are compared in a recirculated electrolysis system. The copper foam shows superior capability for dechlorination of aqueous TCE. Electrolysis by cast iron anode and copper foam cathode is further optimized though a multivariable experimental design and analysis. The conductivity of the electrolyte is identified as an important factor for both final elimination efficiency (FEE) of TCE and specific energy consumption. The copper foam electrode exhibits high TCE elimination efficiency in a wide range of initial TCE concentration. Under coulostatic conditions, the optimal conditions to achieve the highest FEE are 9.525 mm thick copper foam electrode, 40 mA current and 0.042 mol L−1 Na2SO4. This novel electrolysis system is proposed to remediate groundwater contaminated by chlorinated organic solvents, or as an improved iron electrocoagulation process capable of treating the wastewater co-contaminated with chlorinated compounds. PMID:22264798

Microfabricated triggered vacuum switch

DOEpatents

Roesler, Alexander W [Tijeras, NM; Schare, Joshua M [Albuquerque, NM; Bunch, Kyle [Albuquerque, NM

2010-05-11

A microfabricated vacuum switch is disclosed which includes a substrate upon which an anode, cathode and trigger electrode are located. A cover is sealed over the substrate under vacuum to complete the vacuum switch. In some embodiments of the present invention, a metal cover can be used in place of the trigger electrode on the substrate. Materials used for the vacuum switch are compatible with high vacuum, relatively high temperature processing. These materials include molybdenum, niobium, copper, tungsten, aluminum and alloys thereof for the anode and cathode. Carbon in the form of graphitic carbon, a diamond-like material, or carbon nanotubes can be used in the trigger electrode. Channels can be optionally formed in the substrate to mitigate against surface breakdown.

Construction of Hierarchical CuO/Cu₂O@NiCo₂S₄ Nanowire Arrays on Copper Foam for High Performance Supercapacitor Electrodes.

PubMed

Zhou, Luoxiao; He, Ying; Jia, Congpu; Pavlinek, Vladimir; Saha, Petr; Cheng, Qilin

2017-09-15

Hierarchical copper oxide @ ternary nickel cobalt sulfide (CuO/Cu₂O@NiCo₂S₄) core-shell nanowire arrays on Cu foam have been successfully constructed by a facile two-step strategy. Vertically aligned CuO/Cu₂O nanowire arrays are firstly grown on Cu foam by one-step thermal oxidation of Cu foam, followed by electrodeposition of NiCo₂S₄ nanosheets on the surface of CuO/Cu₂O nanowires to form the CuO/Cu₂O@NiCo₂S₄ core-shell nanostructures. Structural and morphological characterizations indicate that the average thickness of the NiCo₂S₄ nanosheets is ~20 nm and the diameter of CuO/Cu₂O core is ~50 nm. Electrochemical properties of the hierarchical composites as integrated binder-free electrodes for supercapacitor were evaluated by various electrochemical methods. The hierarchical composite electrodes could achieve ultrahigh specific capacitance of 3.186 F cm -2 at 10 mA cm -2 , good rate capability (82.06% capacitance retention at the current density from 2 to 50 mA cm -2 ) and excellent cycling stability, with capacitance retention of 96.73% after 2000 cycles at 10 mA cm -2 . These results demonstrate the significance of optimized design and fabrication of electrode materials with more sufficient electrolyte-electrode interface, robust structural integrity and fast ion/electron transfer.

Copper-substituted perovskite compositions for solid oxide fuel cell cathodes and oxygen reduction electrodes in other electrochemical devices

DOEpatents

Rieke, Peter C [Pasco, WA; Coffey, Gregory W [Richland, WA; Pederson, Larry R [Kennewick, WA; Marina, Olga A [Richland, WA; Hardy, John S [Richland, WA; Singh, Prabhaker [Richland, WA; Thomsen, Edwin C [Richland, WA

2010-07-20

The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells. Also provided are electrochemical devices that include active oxygen reduction electrodes, such as solid oxide fuel cells, sensors, pumps and the like. The compositions comprises a copper-substituted ferrite perovskite material. The invention also provides novel methods for making and using the electrode compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having cathodes comprising the compositions.

Study of Pyrex and quartz insulators contamination effect on the X-ray intensity in a 4-kJ plasma focus device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Habibi, M., E-mail: mortezahabibi@aut.ac.ir; Sharifi, R.; Amrollahi, R.

2013-12-15

The variation of the X-ray intensity has been investigated with the Pyrex and quartz insulators surface contamination in a 4-kJ plasma focus device with argon gas at 11.5-kV charging voltage. Elemental analysis (EDAX) showed that the Cu evaporated from the electrode material and was deposited on the sleeve surface improves the breakdown conditions. A small level of sleeve contamination by copper is found to be essential for good focusing action and high HXR intensity. The SEM imaging showed the grain-type structure of Cu formed on the surface and it changed the surface property. Resistance measurements of original and coated Pyrexmore » surface proved that the copper deposition on the sleeve surface will reduce its resistance as compared to the almost infinitely large resistance of the uncontaminated sleeve. As the contamination is surpassed to some critical level, the HXR intensity from the device is deteriorated.« less

Copper and liquid crystal polymer bonding towards lead sensing

NASA Astrophysics Data System (ADS)

Redhwan, Taufique Z.; Alam, Arif U.; Haddara, Yaser M.; Howlader, Matiar M. R.

2018-02-01

Lead (Pb) is a highly toxic and carcinogenic heavy metal causing adverse impacts on environment and human health, thus requiring its careful monitoring. In this work, we demonstrate the integration of copper (Cu) film-based electrodes toward Pb sensing. For this, we developed a direct bonding method for Cu thin film and liquid crystal polymer (LCP) substrate using oxygen plasma treatment followed by contact and heat at 230 °C. The oxygen plasma activation forms hydroxyl groups (OH-) on Cu and LCP. The activated surfaces further adsorb water molecules when exposed to clean room air during contact. After contact, hydrogen bonds are formed between the OH- groups. The interfacial water is removed when the contacted films are heated, leading to shrinkage of OH- chain. This results in an intermediate oxide layer linking the Cu and C sites of Cu and LCP respectively. A strong adhesion (670 N·m-1) is obtained between Cu/LCP that may offer prolonged use of the electrode without delamination in wet sensing applications. Anodic stripping voltammetry of Pb using Cu thin film electrode shows a stronger current peak than sputtered Cu electrode, which implies the significance of the direct bonding approach to integrate thin films. We also studied the electrochemical impedance that will enable modeling of integrated environmental sensors for on-site monitoring of heavy metals.

Copper Corrosion Under Non-uniform Magnetic Field in 0.5 M Hydrochloric Acid

NASA Astrophysics Data System (ADS)

Garcia-Ochoa, E.; Corvo, F.; Genesca, J.; Sosa, V.; Estupiñán, P.

2017-05-01

The influence of a magnetic field on the electrochemical reactions taking place at the surface of a copper electrode immersed in a 0.5 M HCl solution at room temperature has been studied. The symmetry axis of the magnetic field was lined up in the same direction of the ion flow to minimize the Lorentz forces. Measurements of potentiodynamic polarization curves, electrochemical impedance spectroscopy and electrochemical noise allow concluding that the magnetic field significantly affects the cathodic reactions, with corrosion rates increasing under the presence of oxygen in acid media and decreasing when oxygen is eliminated.

DNA-modified electrodes fabricated using copper-free click chemistry for enhanced protein detection.

PubMed

Furst, Ariel L; Hill, Michael G; Barton, Jacqueline K

2013-12-31

A method of DNA monolayer formation has been developed using copper-free click chemistry that yields enhanced surface homogeneity and enables variation in the amount of DNA assembled; extremely low-density DNA monolayers, with as little as 5% of the monolayer being DNA, have been formed. These DNA-modified electrodes (DMEs) were characterized visually, with AFM, and electrochemically, and were found to facilitate DNA-mediated reduction of a distally bound redox probe. These low-density monolayers were found to be more homogeneous than traditional thiol-modified DNA monolayers, with greater helix accessibility through an increased surface area-to-volume ratio. Protein binding efficiency of the transcriptional activator TATA-binding protein (TBP) was also investigated on these surfaces and compared to that on DNA monolayers formed with standard thiol-modified DNA. Our low-density monolayers were found to be extremely sensitive to TBP binding, with a signal decrease in excess of 75% for 150 nM protein. This protein was detectable at 4 nM, on the order of its dissociation constant, with our low-density monolayers. The improved DNA helix accessibility and sensitivity of our low-density DNA monolayers to TBP binding reflects the general utility of this method of DNA monolayer formation for DNA-based electrochemical sensor development.

High efficiency graphene coated copper based thermocells connected in series

NASA Astrophysics Data System (ADS)

Sindhuja, Mani; Indubala, Emayavaramban; Sudha, Venkatachalam; Harinipriya, Seshadri

2018-04-01

Conversion of low-grade waste heat into electricity had been studied employing single thermocell or flowcells so far. Graphene coated copper electrodes based thermocells connected in series displayed relatively high efficiency of thermal energy harvesting. The maximum power output of 49.2W/m2 for normalized cross sectional electrode area is obtained at 60ºC of inter electrode temperature difference. The relative carnot efficiency of 20.2% is obtained from the device. The importance of reducing the mass transfer and ion transfer resistance to improve the efficiency of the device is demonstrated. Degradation studies confirmed mild oxidation of copper foil due to corrosion caused by the electrolyte.

Investigation the electroplating behavior of self formed CuMn barrier.

PubMed

Wu, Chia-Yang; Lee, Wen-Hsi; Chang, Shih-Chieh; Wang, Ying-Lang

2013-08-01

The electrical and material properties of Copper (Cu) mixed with [0-10 atomic% manganese (Mn)] and pure Cu films deposited on silicon oxide (SiO2)/silicon (Si) are explored. Cu electroplating on self formed CuMn barrier was investigated with different Mn content. The electrochemical deposition of the Cu thin film onto the electrode using CuMn barrier was investigated. Scanning electron microscopic (SEM) micrographs of copper electroplating on CuMn films were examined, and the copper nucleation behaviors changed with the Mn content. Since the electrochemical impedance spectroscopy (EIS) is widely recognized as a powerful tool for the investigation of electrochemical behaviors, the tool was also used to verify the phenomena during plating. It was found that the charge-trasfer impedance decrease with the rise in the Mn content below 5%, but increase with the rise in the Mn content higher than 5%. The result was corresponded to the surface energy, the surface morphology, the corrosion and the oxidation of the substrate.

Hardness and wear analysis of Cu/Al2O3 composite for application in EDM electrode

NASA Astrophysics Data System (ADS)

Hussain, M. Z.; Khan, U.; Jangid, R.; Khan, S.

2018-02-01

Ceramic materials, like Aluminium Oxide (Al2O3), have high mechanical strength, high wear resistance, high temperature resistance and good chemical durability. Powder metallurgy processing is an adaptable method commonly used to fabricate composites because it is a simple method of composite preparation and has high efficiency in dispersing fine ceramic particles. In this research copper and novel material aluminium oxide/copper (Al2O3/Cu) composite has been fabricated for the application of electrode in Electro-Discharge Machine (EDM) using powder metallurgy technique. Al2O3 particles with different weight percentages (0, 1%, 3% and 5%) were reinforced into copper matrix using powder metallurgy technique. The powders were blended and compacted at a load of 100MPa to produce green compacts and sintered at a temperature of 574 °C. The effect of aluminium oxide content on mass density, Rockwell hardness and wear behaviour were investigated. Wear behaviour of the composites was investigated on Die-Sink EDM (Electro-Discharge Machine). It was found that wear rate is highly depending on hardness, mass density and green protective carbonate layer formation at the surface of the composite.

Investigation of Machine-ability of Inconel 800 in EDM with Coated Electrode

NASA Astrophysics Data System (ADS)

Karunakaran, K.; Chandrasekaran, M.

2017-03-01

The Inconel 800 is a high temperature application alloy which is classified as a nickel based super alloy. It has wide scope in aerospace engineering, gas Turbine etc. The machine-ability studies were found limited on this material. Hence This research focuses on machine-ability studies on EDM of Inconel 800 with Silver Coated Electrolyte Copper Electrode. The purpose of coating on electrode is to reduce tool wear. The factors pulse on Time, Pulse off Time and Peck Current were considered to observe the responses of surface roughness, material removal rate, tool wear rate. Taguchi Full Factorial Design is employed for Design the experiment. Some specific findings were reported and the percentage of contribution of each parameter was furnished

Properties of thermal air plasma with admixing of copper and carbon

NASA Astrophysics Data System (ADS)

Fesenko, S.; Veklich, A.; Boretskij, V.; Cressault, Y.; Gleizes, A.; Teulet, Ph

2014-11-01

This paper deals with investigations of air plasma with admixing of copper and carbon. Model plasma source unit with real breaking arc was used for the simulation of real discharges, which can be occurred during sliding of Cu-C composite electrodes on copper wire at electromotive vehicles. The complex technique of plasma property studies is developed. From one hand, the radial profiles of temperature and electron density in plasma of electric arc discharge in air between Cu-C composite and copper electrodes in air flow were measured by optical spectroscopy techniques. From another hand, the radial profiles of electric conductivity of plasma mixture were calculated by solution of energy balance equation. It was assumed that the thermal conductivity of air plasma is not depending on copper or carbon vapor admixtures. The electron density is obtained from electric conductivity profiles by calculation in assumption of local thermodynamic equilibrium in plasma. Computed in such way radial profiles of electron density in plasma of electric arc discharge in air between copper electrodes were compared with experimentally measured profiles. It is concluded that developed techniques of plasma diagnostics can be reasonably used in investigations of thermal plasma with copper and carbon vapors.

A selective potentiometric copper (II) ion sensor based on the functionalized ZnO nanorods.

PubMed

Khun, K; Ibupoto, Z H; Liu, X; Nur, O; Willander, M; Danielsson, B

2014-09-01

In this work, ZnO nanorods were hydrothermally grown on the gold-coated glass substrate and characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) techniques. The ZnO nanorods were functionalized by two different approaches and performance of the sensor electrode was monitored. Fourier transform infrared spectroscopy (FTIR) was carried out for the confirmation of interaction between the ionophore molecules and ZnO nanorods. In addition to this, the surface of the electrode was characterized by X-ray photoelectron spectroscopy (XPS) showing the chemical and electronic state of the ionophore and ZnO nanorod components. The ionophore solution was prepared in the stabilizer, poly vinyl chloride (PVC) and additives, and then functionalized on the ZnO nanorods that have shown the Nernstian response with the slope of 31 mV/decade. However, the Cu2+ ion sensor was fabricated only by immobilizing the selective copper ion ionophore membrane without the use of PVC, plasticizers, additives and stabilizers and the sensor electrode showed a linear potentiometric response with a slope of 56.4 mV/decade within a large dynamic concentration range (from 1.0 x 10(-6) to 1.0 x 10(-1) M) of copper (II) nitrate solutions. The sensor showed excellent repeatability and reproducibility with response time of less than 10 s. The negligible response to potentially interfering metal ions such as calcium (Ca2+), magnesium (Mg2+), potassium (K+), iron (Fe3+), zinc (Zn2+), and sodium (Na+) allows this sensor to be used in biological studies. It may also be used as an indicator electrode in the potentiometric titration.

Vertically Aligned Carbon Nanotube Electrodes for Lithium-Ion Batteries

DTIC Science & Technology

2011-01-01

wpafb.af.mil (M.F. Durstock). [11] nanowires, and iron oxide/copper [12] and tin/copper [13] nanorods. Carbon nanotubes ( CNTs ) have also been examined as...negative electrodes [14–17]. Although CNTs and other nega- tive electrode nanomaterials have been shown to exhibit similar or greater capacities...rate capability [18]. Studies suggest that aligned CNTs could allow for better contact with the current collector and increased ion diffu- sivity to

Fabrication of free-standing copper foils covered with highly-ordered copper nanowire arrays

NASA Astrophysics Data System (ADS)

Zaraska, Leszek; Sulka, Grzegorz D.; Jaskuła, Marian

2012-07-01

The through-hole nanoporous anodic aluminum oxide (AAO) membranes with relatively large surface area (ca. 2 cm2) were employed for fabrication of free-standing and mechanically stable copper foils covered with close-packed and highly-ordered copper nanowire arrays. The home-made AAO membranes with different pore diameters and interpore distances were fabricated via a two-step self-organized anodization of aluminum performed in sulfuric acid, oxalic acid and phosphoric acid followed by the pore opening/widening procedure. The direct current (DC) electrodeposition of copper was performed efficiently on both sides of AAO templates. The bottom side of the AAO templates was not insulated and consequently Cu nanowire arrays on thick Cu layers were obtained. The proposed template-assisted fabrication of free-standing copper nanowire array electrodes is a promising method for synthesis of nanostructured current collectors. The composition of Cu nanowires was confirmed by energy dispersive X-Ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The structural features of nanowires were evaluated from field emission scanning electron microscopy (FE-SEM) images and compared with the characteristic parameters of anodic alumina membranes.

New Three-Dimensional Porous Electrode Concept: Vertically-Aligned Carbon Nanotubes Directly Grown on Embroidered Copper Structures.

PubMed

Aguiló-Aguayo, Noemí; Amade, Roger; Hussain, Shahzad; Bertran, Enric; Bechtold, Thomas

2017-12-11

New three-dimensional (3D) porous electrode concepts are required to overcome limitations in Li-ion batteries in terms of morphology (e.g., shapes, dimensions), mechanical stability (e.g., flexibility, high electroactive mass loadings), and electrochemical performance (e.g., low volumetric energy densities and rate capabilities). Here a new electrode concept is introduced based on the direct growth of vertically-aligned carbon nanotubes (VA-CNTs) on embroidered Cu current collectors. The direct growth of VA-CNTs was achieved by plasma-enhanced chemical vapor deposition (PECVD), and there was no application of any post-treatment or cleaning procedure. The electrochemical behavior of the as-grown VA-CNTs was analyzed by charge/discharge cycles at different specific currents and with electrochemical impedance spectroscopy (EIS) measurements. The results were compared with values found in the literature. The as-grown VA-CNTs exhibit higher specific capacities than graphite and pristine VA-CNTs found in the literature. This together with the possibilities that the Cu embroidered structures offer in terms of specific surface area, total surface area, and designs provide a breakthrough in new 3D electrode concepts.

Facile Synthesis of Ultralong and Thin Copper Nanowires and Its Application to High-Performance Flexible Transparent Conductive Electrodes

NASA Astrophysics Data System (ADS)

Wang, Yaxiong; Liu, Ping; Zeng, Baoqing; Liu, Liming; Yang, Jianjun

2018-03-01

A hydrothermal method for synthesizing ultralong and thin copper nanowires (CuNWs) with average diameter of 35 nm and average length of 100 μm is demonstrated in this paper. The concerning raw materials include copric (II) chloride dihydrate (CuCl2·2H2O), octadecylamine (ODA), and ascorbic acid, which are all very cheap and nontoxic. The effect of different reaction time and different molar ratios to the reaction products were researched. The CuNWs prepared by the hydrothermal method were applied to fabricate CuNW transparent conductive electrode (TCE), which exhibited excellent conductivity-transmittance performance with low sheet resistance of 26.23 Ω /\\square and high transparency at 550 nm of 89.06% (excluding Polyethylene terephthalate (PET) substrate). The electrode fabrication process was carried out at room temperature, and there was no need for post-treatment. In order to decrease roughness and protect CuNW TCEs against being oxidized, we fabricated CuNW/poly(methyl methacrylate) (PMMA) hybrid TCEs (HTCEs) using PMMA solution. The CuNW/PMMA HTCEs exhibited low surface roughness and chemical stability as compared with CuNW TCEs.

The preparation of copper fine particle paste and its application as the inner electrode material of a multilayered ceramic capacitor

NASA Astrophysics Data System (ADS)

Yonezawa, Tetsu; Takeoka, Shinsuke; Kishi, Hiroshi; Ida, Kiyonobu; Tomonari, Masanori

2008-04-01

Well size-controlled copper fine particles (diameter: 100-300 nm) were used as the inner electrode material of multilayered ceramic capacitors (MLCCs). The particles were dispersed in terpineol to form a printing paste with 50 wt% copper particles. The MLCC precursor modules prepared by the layer-by-layer printing of copper and BaTiO3 particles were cosintered. Detailed observation of the particles, paste, and MLCCs before and after sintering was carried out by electron microscopy. The sintering temperature of Cu-MLCC was as low as 960 °C. The permittivity of these MLCCs was successfully measured with the copper inner layers.

Construction of Hierarchical CuO/Cu2O@NiCo2S4 Nanowire Arrays on Copper Foam for High Performance Supercapacitor Electrodes

PubMed Central

Zhou, Luoxiao; He, Ying; Jia, Congpu; Pavlinek, Vladimir; Saha, Petr; Cheng, Qilin

2017-01-01

Hierarchical copper oxide @ ternary nickel cobalt sulfide (CuO/Cu2O@NiCo2S4) core-shell nanowire arrays on Cu foam have been successfully constructed by a facile two-step strategy. Vertically aligned CuO/Cu2O nanowire arrays are firstly grown on Cu foam by one-step thermal oxidation of Cu foam, followed by electrodeposition of NiCo2S4 nanosheets on the surface of CuO/Cu2O nanowires to form the CuO/Cu2O@NiCo2S4 core-shell nanostructures. Structural and morphological characterizations indicate that the average thickness of the NiCo2S4 nanosheets is ~20 nm and the diameter of CuO/Cu2O core is ~50 nm. Electrochemical properties of the hierarchical composites as integrated binder-free electrodes for supercapacitor were evaluated by various electrochemical methods. The hierarchical composite electrodes could achieve ultrahigh specific capacitance of 3.186 F cm−2 at 10 mA cm−2, good rate capability (82.06% capacitance retention at the current density from 2 to 50 mA cm−2) and excellent cycling stability, with capacitance retention of 96.73% after 2000 cycles at 10 mA cm−2. These results demonstrate the significance of optimized design and fabrication of electrode materials with more sufficient electrolyte-electrode interface, robust structural integrity and fast ion/electron transfer. PMID:28914819

Controlling the set of carbon-fiber embedded cement with electric current

DOEpatents

Mattus, Alfred J.

2004-06-15

A method for promoting cement or concrete set on demand for concrete that has been chemically retarded by adding carbon fiber to the concrete, which enables it to become electrically conductive, sodium tartrate retardant, and copper sulfate which forms a copper tartrate complex in alkaline concrete mixes. Using electricity, the concrete mix anodically converts the retarding tartrate to an insoluble polyester polymer. The carbon fibers act as a continuous anode surface with a counter electrode wire embedded in the mix. Upon energizing, the retarding effect of tartrate is defeated by formation of the polyester polymer through condensation esterification thereby allowing the normal set to proceed unimpeded.

Galvanostatic electrodeposition of copper nanoparticles on screen-printed carbon electrodes and their application for reducing sugars determination.

PubMed

Pérez-Fernández, Beatriz; Martín-Yerga, Daniel; Costa-García, Agustín

2017-12-01

In this work, a novel method for the galvanostatic electrodeposition of copper nanoparticles on screen-printed carbon electrodes was developed. Nanoparticles of spherical morphology with sizes between 60 and 280nm were obtained. The electrocatalytic effect of these copper nanospheres towards the oxidation of different sugars was studied. Excellent analytical performance was obtained with the nanostructured sensor: low detection limits and wide linear ranges (1-10,000µM) were achieving for the different reducing sugars evaluated (glucose, fructose, arabinose, galactose, mannose, xylose) with very similar calibration slopes, which demonstrates the possibility of total sugar detection. The reproducibility of these sensors was 4.4% (intra-electrode) and 7.2% (inter-electrode). The stability of the nanostructured electrodes was at least 30 days, even using the same device on different days. Several real samples (honey, orange juice and normal and sugar-free soft drinks) were evaluated to study the reliability of the nanostructured sensor. Copyright © 2017 Elsevier B.V. All rights reserved.

Specific anion effects on copper surface through electrochemical treatment: Enhanced photoelectrochemical CO2 reduction activity of derived nanostructures induced by chaotropic anions

NASA Astrophysics Data System (ADS)

Navaee, Aso; Salimi, Abdollah

2018-05-01

Copper derivatives are the most prominent CO2 reduction electrocatalyst. Herein, the metallic copper has been electrochemically treated with some of common ionic salts such as N3bar, HPO2bar, S2bar, Fbar, Clbar, Brbar and Ibar based on the dissolution of a metallic working electrode in an aqueous solution to derive the surface roughness incorporated with nanostructures. Diverse surface morphology can be obtained when the ionic radii of anions are changed. Surface study reveals various roughness shapes based on the size and polarity of the anions, where the ions with higher ionic radii have higher impact on the Cu surface. In comparison, polyatomic oxyanion such as HPO2bar even with large ionic radii do not have enough strength to create the surface roughness than that of oxygen-free anions with large ionic radii. The photoelectrochemical behavior of the modified surfaces toward CO2 reduction is studied at a wide potential window in bicarbonate aqueous solution. Based on our investigations, treated surfaces by Ibar, Clbar and S2bargive a more surface roughness, while Ibar and N3bar offer higher catalytic activity toward CO2 reduction due to possible complexing ability of these anions with Cu cations, followed by formation of the co-catalyst semiconductor and facilitate electron transfer. This methodology can be applied to investigate the effect of ions on transition metals along with obtaining different surface morphologies tailored to different applications.

Investigation and Synthesis of High Temperature and Increased Stiffness RSP Aluminum Alloys

DTIC Science & Technology

1988-11-30

under argon atmosphere using a water cooled copper crucible and a non-consumable tungsten electrode. This pro- cedure was followed in previous studies... copper crucible and a non-consum- able tungsten electrode. This procedure was followed in previous studies of Al-Zr-V (5,7). * Presently with National

Fiber optic apparatus for detecting molecular species by surface enhanced Raman spectroscopy

DOEpatents

Angel, S.M.; Sharma, S.K.

1988-11-01

Optrode apparatus for detecting constituents of a fluid medium includes an optical fiber having a metal coating on at least a portion of a light transmissive core. The metal is one, such as silver, gold or copper, which enhances emission of Raman signal frequencies by molecules adsorbed on the surface of the coating when monochromatic probe light of a different frequency is scattered by such molecules and the metal coating is sufficiently thin to transmit light between the absorbed molecules and the core of the fiber. Probe light is directed into one end of the fiber and a detector analyzes light emitted from the fiber for Raman frequencies that identify one or more particular molecular species. In one form, the optrode may function as a working electrode of an electrochemical cell while also serving to detect the products of oxidation or reduction reactions which occur at the electrode surface. 6 figs.

Fiber optic apparatus for detecting molecular species by surface enhanced Raman spectroscopy

DOEpatents

Angel, S.M.; Sharma, S.K.

1987-11-30

Optrode apparatus for detecting constituents of a fluid medium includes an optical fiber having a metal coating on at least a portion of a light transmissive core. The metal is one, such as silver, gold or copper, which enhances emission of Raman signal frequencies by molecules adsorbed on the surface of the coating when monochromatic probe light of a different frequency is scattered by such molecules and the metal coating is sufficiently thin to transmit light between the adsorbed molecules and the core of the fiber. Probe light is directed into one end of the fiber and a detector analyzes light emitted from the fiber for Raman frequencies that identify one or more particular molecular species. In one form, the optrode may function as a working electrode of an electrochemical cell while also serving to detect the products of oxidation or reduction reactions which occur at the electrode surface. 6 figs.

CSSC Fish Barrier Simulated Rescuer Touch Point Results, Operating Guidance, and Recommendations for Rescuer Safety

DTIC Science & Technology

2011-03-01

Mile per hour ms Millisecond NEDU Navy Experimental Diving Unit PFD Personal flotation device PIW Person in the water PVC Polyvinyl chloride RDC...electrically resistive, yet conductive, clay. We then encapsulated the clay around a 1/2” diameter, 6-inch long copper rod, and then tightly wrapped it with...short length of 12 American Wire Gauge (AWG) stranded copper wire to the copper rod within each electrode. For each electrode pair, we joined

Simultaneous Automatic Electrochemical Detection of Zinc, Cadmium, Copper and Lead Ions in Environmental Samples Using a Thin-Film Mercury Electrode and an Artificial Neural Network

PubMed Central

Kudr, Jiri; Nguyen, Hoai Viet; Gumulec, Jaromir; Nejdl, Lukas; Blazkova, Iva; Ruttkay-Nedecky, Branislav; Hynek, David; Kynicky, Jindrich; Adam, Vojtech; Kizek, Rene

2015-01-01

In this study a device for automatic electrochemical analysis was designed. A three electrodes detection system was attached to a positioning device, which enabled us to move the electrode system from one well to another of a microtitre plate. Disposable carbon tip electrodes were used for Cd(II), Cu(II) and Pb(II) ion quantification, while Zn(II) did not give signal in this electrode configuration. In order to detect all mentioned heavy metals simultaneously, thin-film mercury electrodes (TFME) were fabricated by electrodeposition of mercury on the surface of carbon tips. In comparison with bare electrodes the TMFEs had lower detection limits and better sensitivity. In addition to pure aqueous heavy metal solutions, the assay was also performed on mineralized rock samples, artificial blood plasma samples and samples of chicken embryo organs treated with cadmium. An artificial neural network was created to evaluate the concentrations of the mentioned heavy metals correctly in mixture samples and an excellent fit was observed (R2 = 0.9933). PMID:25558996

Glucose sensing on graphite screen-printed electrode modified by sparking of copper nickel alloys.

PubMed

Riman, Daniel; Spyrou, Konstantinos; Karantzalis, Alexandros E; Hrbac, Jan; Prodromidis, Mamas I

2017-04-01

Electric spark discharge was employed as a green, fast and extremely facile method to modify disposable graphite screen-printed electrodes (SPEs) with copper, nickel and mixed copper/nickel nanoparticles (NPs) in order to be used as nonenzymatic glucose sensors. Direct SPEs-to-metal (copper, nickel or copper/nickel alloys with 25/75, 50/50 and 75/25wt% compositions) sparking at 1.2kV was conducted in the absence of any solutions under ambient conditions. Morphological characterization of the sparked surfaces was performed by scanning electron microscopy, while the chemical composition of the sparked NPs was evaluated with energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The performance of the various sparked SPEs towards the electro oxidation of glucose in alkaline media and the critical role of hydroxyl ions were evaluated with cyclic voltammetry and kinetic studies. Results indicated a mixed charge transfer- and hyroxyl ion transport-limited process. Best performing sensors fabricated by Cu/Ni 50/50wt% alloy showed linear response over the concentration range 2-400μM glucose and they were successfully applied to the amperometric determination of glucose in blood. The detection limit (S/N 3) and the relative standard deviation of the method were 0.6µM and <6% (n=5, 2µM glucose), respectively. Newly devised sparked Cu/Ni graphite SPEs enable glucose sensing with distinct advantages over existing glucose chemical sensors in terms of cost, fabrication simplicity, disposability, and adaptation of green methods in sensor's development. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of total and electrolabile copper in agricultural soil by using disposable modified-carbon screen-printed electrodes.

PubMed

Faucher, Stéphane; Cugnet, Cyril; Authier, Laurent; Lespes, Gaëtane

2014-02-01

The objective of the study is to evaluate modified-carbon screen-printed working electrodes (SPE) combined with square wave anodic stripping voltammetry (SWASV) to determine electrolabile and total copper in soils with the perspective to assess the environmental hazard resulting from copper anthropogenic contamination. The voltammetric method was investigated using a mineralized certified reference soil such that it can be assumed that the copper was totally under electrolabile form in the solution of mineralized soil. In optimal conditions, a copper recovery of 97% and a relative standard deviation (RSD) of 9% were found. The limits of detection and quantification for copper were 0.4 and 1.3 μg L(-1), respectively. Finally, the method was applied on soil leachates, which allowed evaluating the cupric transfer from the soil to the leachates and quantifying the electrolabile copper part in leachates.

Chalcogenide Nanoionic-based Radio Frequency Switch

NASA Technical Reports Server (NTRS)

Nessel, James (Inventor); Lee, Richard (Inventor)

2013-01-01

A nonvolatile nanoionic switch is disclosed. A thin layer of chalcogenide glass engages a substrate and a metal selected from the group of silver and copper photo-dissolved in the chalcogenide glass. A first oxidizable electrode and a second inert electrode engage the chalcogenide glass and are spaced apart from each other forming a gap therebetween. A direct current voltage source is applied with positive polarity applied to the oxidizable electrode and negative polarity applied to the inert electrode which electrodeposits silver or copper across the gap closing the switch. Reversing the polarity of the switch dissolves the electrodeposited metal and returns it to the oxidizable electrode. A capacitor arrangement may be formed with the same structure and process.

Chalcogenide Nanoionic-Based Radio Frequency Switch

NASA Technical Reports Server (NTRS)

Nessel, James (Inventor); Lee, Richard (Inventor)

2011-01-01

A nonvolatile nanoionic switch is disclosed. A thin layer of chalcogenide glass engages a substrate and a metal selected from the group of silver and copper photo-dissolved in the chalcogenide glass. A first oxidizable electrode and a second inert electrode engage the chalcogenide glass and are spaced apart from each other forming a gap there between. A direct current voltage source is applied with positive polarity applied to the oxidizable electrode and negative polarity applied to the inert electrode which electrodeposits silver or copper across the gap closing the switch. Reversing the polarity of the switch dissolves the electrodeposited metal and returns it to the oxidizable electrode. A capacitor arrangement may be formed with the same structure and process.

Patterning of colloidal particles in the galvanic microreactor

NASA Astrophysics Data System (ADS)

Jan, Linda

A Cu-Au galvanic microreactor is used to demonstrate the autonomous patterning of two-dimensional colloidal crystals with spatial and orientational order which are adherent to the electrode substrate. The microreactor is comprised of a patterned array of copper and gold microelectrodes in a coplanar arrangement that is immersed in a dilute hydrochloric acid solution in which colloidal polystyrene microspheres are suspended. During the electrochemical dissolution of copper, polystyrene colloids are transported to the copper electrodes. The spatial arrangement of the electrodes determines whether the colloids initiate aggregation at the edges or centers of the copper electrodes. Depending on the microreactor parameters, two-dimensional colloidal crystals can form and adhere to the electrode. This thesis investigates the mechanisms governing the autonomous particle motion, the directed particle trajectory (inner- versus edge-aggregation) as affected by the spatial patterning of the electrodes, and the adherence of the colloidal particles onto the substrate. Using in situ current density measurements, particle velocimetry, and order-of-magnitude arguments, it is shown that particle motion is governed by bulk fluid motion and electrophoresis induced by the electrochemical reactions. Bulk electrolyte flow is most likely driven by electrochemical potential gradients of reaction products formed during the inhomogeneous copper dissolution, particularly due to localized high current density at the electrode junction. Preferential aggregation of the colloidal particles resulting in inner- and edge-aggregation is influenced by changes to the flow pattern in response to difference in current density profiles as affected by the spatial patterning of the electrode. Finally, by determining the onset of particle cementation through particle tracking analysis, and by monitoring the deposition of reaction products through the observation of color changes of the galvanic electrodes in situ, it is shown that particle cementation coincides with the precipitation and deposition of reaction products. The precipitation process is caused by shifts in the chemical equilibria of the microreactor due to changes in the composition of the electrolyte during the reactions, which can be used to control particle cementation. The corrosion driven transport, deposition and adherence of colloidal particles at corrosion sites have implications for the development of autonomous self-healing materials.

TSDC (Thermally Stimulated Depolarization Current) Studies of PEO (Poly(Ethylene Oxide)) and PEO Complexed with KSCN.

DTIC Science & Technology

1985-06-01

evaporated onto the resulting films. These films were then cut to form disks about 8 mm in diameter and 0.7 mm thick. While one electrode covered the full...surrounded by a heating coil, inside an airtight chamber. A spring loaded brass electrode presses the sample and the other electrode ." down onto the copper...cylinder. A sapphire disk insulates the lower " lectrodh( from the copper. This arrangement guarantees good thermal contact, arid electrical

Simultaneous determination of isoproterenol, acetaminophen, folic acid, propranolol and caffeine using a sensor platform based on carbon black, graphene oxide, copper nanoparticles and PEDOT:PSS.

PubMed

Wong, Ademar; Santos, Anderson Martin; Silva, Tiago Almeida; Fatibello-Filho, Orlando

2018-06-01

We explored the use of carbon black (CB), graphene oxide (GO), copper nanoparticles (CuNPs) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as electrode materials for the simultaneous determination of isoproterenol, acetaminophen, folic acid, propranolol and caffeine. The designed nanostructured surface was widely characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), contact angle measurements and electrochemistry. From electrochemical characterization assays carried out towards the potassium ferricyanide redox probe, fast electron transfer kinetics and a considerably higher electroactive surface area were observed for the modified electrodic surface based on CB, GO, CuNPs and PEDOT:PSS film. Using square-wave voltammetry (SWV), well defined and resolved anodic peaks were detected for isoproterenol, acetaminophen, folic acid, propranolol and caffeine, with peak-to-peak potential separation not less than 170 mV. Then, the SWV technique was explored for the simultaneous determination of quinary mixtures of these analytes, resulting in analytical curves with linear ranges and limits of detection at micromolar concentration levels. The practical viability of the proposed voltammetric sensor was illustrated in the analysis of human body fluid samples. The proposed sensor showed good repeatability and a successful application using urine and serum matrices, with recoveries close to 100%. Copyright © 2018 Elsevier B.V. All rights reserved.

Direct growth of metal-organic frameworks thin film arrays on glassy carbon electrode based on rapid conversion step mediated by copper clusters and hydroxide nanotubes for fabrication of a high performance non-enzymatic glucose sensing platform.

PubMed

Shahrokhian, Saeed; Khaki Sanati, Elnaz; Hosseini, Hadi

2018-07-30

The direct growth of self-supported metal-organic frameworks (MOFs) thin film can be considered as an effective strategy for fabrication of the advanced modified electrodes in sensors and biosensor applications. However, most of the fabricated MOFs-based sensors suffer from some drawbacks such as time consuming for synthesis of MOF and electrode making, need of a binder or an additive layer, need of expensive equipment and use of hazardous solvents. Here, a novel free-standing MOFs-based modified electrode was fabricated by the rapid direct growth of MOFs on the surface of the glassy carbon electrode (GCE). In this method, direct growth of MOFs was occurred by the formation of vertically aligned arrays of Cu clusters and Cu(OH) 2 nanotubes, which can act as both mediator and positioning fixing factor for the rapid formation of self-supported MOFs on GCE surface. The effect of both chemically and electrochemically formed Cu(OH) 2 nanotubes on the morphological and electrochemical performance of the prepared MOFs were investigated. Due to the unique properties of the prepared MOFs thin film electrode such as uniform and vertically aligned structure, excellent stability, high electroactive surface area, and good availability to analyte and electrolyte diffusion, it was directly used as the electrode material for non-enzymatic electrocatalytic oxidation of glucose. Moreover, the potential utility of this sensing platform for the analytical determination of glucose concentration was evaluated by the amperometry technique. The results proved that the self-supported MOFs thin film on GCE is a promising electrode material for fabricating and designing non-enzymatic glucose sensors. Copyright © 2018 Elsevier B.V. All rights reserved.

Determination of heavy metals in mussel and oyster samples with tris (2,2‧-bipyridyl) ruthenium (II)/graphene/Nafion® modified glassy carbon electrodes

NASA Astrophysics Data System (ADS)

Palisoc, Shirley T.; Uy, Donald Jans S.; Natividad, Michelle T.; Lopez, Toni Beth G.

2017-11-01

Tris (2,2‧-bipyridyl)ruthenium(II)/graphene/Nafion® modified glassy carbon electrodes (GCEs) were fabricated using the drop coating method. The modified electrode was used as the working electrode in differential pulse voltammetry (DPV) for the determination of lead, cadmium, and copper in mussel and oyster samples. The concentration of Tris (2,2‧-bipyridyl) ruthenium (II) and graphene were varied while those of Nafion®, methanol, and ethanol were held constant in the coating solution. The morphology and elemental composition of the fabricated electrodes were analyzed by scanning electron microscopy and energy-dispersive x-ray spectroscopy. Cyclic voltammetry (CV) was done to investigate the reversibility and stability of the modified electrodes. The modified electrode with the best figures of merit was utilized for the detection of copper (Cu2+), lead (Pb2+) and cadmium (Cd2+) via DPV. This was the electrode modified with 4 mg [Ru (bpy)3]2+ and 3 mg graphene. The anodic current and metal concentration showed linear relationship in the range of 48 ppb-745 ppb for Pb2+, 49 ppb-613 ppb for Cd2+, and 28 ppb-472 ppb for Cu2+. The limits of detection for lead, cadmium, and copper were 48 ppb, 49 ppb, and 28 ppb, respectively. Results from atomic absorption spectrometry (AAS) were compared with those measured with DPV. Lead, cadmium, and copper were in mussels, oysters, and sea water. In addition, DPV was able to detect other metals such as zinc, iron, tin and mercury in sea water samples and some samples of oysters.

Hydrogen substituted graphdiyne as carbon-rich flexible electrode for lithium and sodium ion batteries.

PubMed

He, Jianjiang; Wang, Ning; Cui, Zili; Du, Huiping; Fu, Lin; Huang, Changshui; Yang, Ze; Shen, Xiangyan; Yi, Yuanping; Tu, Zeyi; Li, Yuliang

2017-10-27

Organic electrodes are potential alternatives to current inorganic electrode materials for lithium ion and sodium ion batteries powering portable and wearable electronics, in terms of their mechanical flexibility, function tunability and low cost. However, the low capacity, poor rate performance and rapid capacity degradation impede their practical application. Here, we concentrate on the molecular design for improved conductivity and capacity, and favorable bulk ion transport. Through an in situ cross-coupling reaction of triethynylbenzene on copper foil, the carbon-rich frame hydrogen substituted graphdiyne film is fabricated. The organic film can act as free-standing flexible electrode for both lithium ion and sodium ion batteries, and large reversible capacities of 1050 mAh g -1 for lithium ion batteries and 650 mAh g -1 for sodium ion batteries are achieved. The electrode also shows a superior rate and cycle performances owing to the extended π-conjugated system, and the hierarchical pore bulk with large surface area.

Small-Scale and Low Cost Electrodes for "Standard" Reduction Potential Measurements

ERIC Educational Resources Information Center

Eggen, Per-Odd; Kvittingen, Lise

2007-01-01

The construction of three simple and inexpensive electrodes, hydrogen, and chlorine and copper electrode is described. This simple method will encourage students to construct their own electrode and better help in understanding precipitation and other electrochemistry concepts.

Large-scale fabrication of single crystalline tin nanowire arrays

NASA Astrophysics Data System (ADS)

Luo, Bin; Yang, Dachi; Liang, Minghui; Zhi, Linjie

2010-09-01

Large-scale single crystalline tin nanowire arrays with preferred lattice orientation along the [100] direction were fabricated in porous anodic aluminium oxide (AAO) membranes by the electrodeposition method using copper nanorod as a second electrode.Large-scale single crystalline tin nanowire arrays with preferred lattice orientation along the [100] direction were fabricated in porous anodic aluminium oxide (AAO) membranes by the electrodeposition method using copper nanorod as a second electrode. Electronic supplementary information (ESI) available: Experimental details and the information for single crystalline copper nanorods. See DOI: 10.1039/c0nr00206b

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.

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.

Electrochemically induced dual reactive barriers for transformation of TCE and mixture of contaminants in groundwater.

PubMed

Mao, Xuhui; Yuan, Songhu; Fallahpour, Noushin; Ciblak, Ali; Howard, Joniqua; Padilla, Ingrid; Loch-Caruso, Rita; Alshawabkeh, Akram N

2012-11-06

A novel reactive electrochemical flow system consisting of an iron anode and a porous cathode is proposed for the remediation of mixture of contaminants in groundwater. The system consists of a series of sequentially arranged electrodes, a perforated iron anode, a porous copper cathode followed by a mesh-type mixed metal oxide anode. The iron anode generates ferrous species and a chemically reducing environment, the porous cathode provides a reactive electrochemically reducing barrier, and the inert anode provides protons and oxygen to neutralize the system. The redox conditions of the electrolyte flowing through this system can be regulated by controlling the distribution of the electric current. Column experiments are conducted to evaluate the process and study the variables. The electrochemical reduction on a copper foam cathode produced an electrode-based reductive potential capable of reducing TCE and nitrate. Rational electrodes arrangement, longer residence time of electrolytes and higher surface area of the foam electrode improve the reductive transformation of TCE. More than 82.2% TCE removal efficiency is achieved for the case of low influent concentration (<7.5 mg/L) and high current (>45 mA). The ferrous species produced from the iron anode not only enhance the transformation of TCE on the cathode, but also facilitates transformation of other contaminants including dichromate, selenate and arsenite. Removal efficiencies greater than 80% are achieved for these contaminants in flowing contaminated water. The overall system, comprising the electrode-based and electrolyte-based barriers, can be engineered as a versatile and integrated remedial method for a relatively wide spectrum of contaminants and their mixtures.

LabVIEW-based sequential-injection analysis system for the determination of trace metals by square-wave anodic and adsorptive stripping voltammetry on mercury-film electrodes.

PubMed

Economou, Anastasios; Voulgaropoulos, Anastasios

2003-01-01

The development of a dedicated automated sequential-injection analysis apparatus for anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (AdSV) is reported. The instrument comprised a peristaltic pump, a multiposition selector valve and a home-made potentiostat and used a mercury-film electrode as the working electrodes in a thin-layer electrochemical detector. Programming of the experimental sequence was performed in LabVIEW 5.1. The sequence of operations included formation of the mercury film, electrolytic or adsorptive accumulation of the analyte on the electrode surface, recording of the voltammetric current-potential response, and cleaning of the electrode. The stripping step was carried out by applying a square-wave (SW) potential-time excitation signal to the working electrode. The instrument allowed unattended operation since multiple-step sequences could be readily implemented through the purpose-built software. The utility of the analyser was tested for the determination of copper(II), cadmium(II), lead(II) and zinc(II) by SWASV and of nickel(II), cobalt(II) and uranium(VI) by SWAdSV.

LabVIEW-based sequential-injection analysis system for the determination of trace metals by square-wave anodic and adsorptive stripping voltammetry on mercury-film electrodes

PubMed Central

Economou, Anastasios; Voulgaropoulos, Anastasios

2003-01-01

The development of a dedicated automated sequential-injection analysis apparatus for anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (AdSV) is reported. The instrument comprised a peristaltic pump, a multiposition selector valve and a home-made potentiostat and used a mercury-film electrode as the working electrodes in a thin-layer electrochemical detector. Programming of the experimental sequence was performed in LabVIEW 5.1. The sequence of operations included formation of the mercury film, electrolytic or adsorptive accumulation of the analyte on the electrode surface, recording of the voltammetric current-potential response, and cleaning of the electrode. The stripping step was carried out by applying a square-wave (SW) potential-time excitation signal to the working electrode. The instrument allowed unattended operation since multiple-step sequences could be readily implemented through the purpose-built software. The utility of the analyser was tested for the determination of copper(II), cadmium(II), lead(II) and zinc(II) by SWASV and of nickel(II), cobalt(II) and uranium(VI) by SWAdSV. PMID:18924623

A novel route for electrosynthesis of CuCr(2)O(4) nanocomposite with p-type conductive polymer as a high performance material for electrochemical supercapacitors.

PubMed

Shayeh, Javad Shabani; Sadeghinia, Mohammad; Siadat, Seyed Omid Ranaei; Ehsani, Ali; Rezaei, Mehran; Omidi, Meisam

2017-06-15

In this work, supercapacitive performance of polypyrrole copper chromate nano particles (Ppy/CuCr 2 O 4 NPs) was studied. CuCr 2 O 4 NPs with the average size of 20nm were synthesized simply by hydrothermal method and the composite electrodes were then electropolymerized on the surface of glassy carbon electrode. Common surface analysis techniques such as scanning electron microscopy (SEM), transmission electron microscopy(TEM) and Fourier transform infrared (FTIR) were used to study the morphology and structure of the composite. Furthermore, for electrochemical evaluation of composite electrodes, techniques including cyclic voltammetry (CV), galvanostatic charge discharge (CD) and impedance spectroscopy (EIS) were used. Using cyclic voltammetry, the specific capacitance values of Ppy and Ppy/CuCr 2 O 4 NPs were calculated to be 109 and 508 F g -1 , respectively. Results show that using CuCr 2 O 4 NPs in the structure of polymeric films led to increased specific capacitance of composite electrodes more than four times that of poly pyrrole. Increasing the conductivity and stability of composite electrodes through continuous cycles are the other advantages of using CuCr 2 O 4 NPs as active materials in a polymeric structure. Copyright © 2017 Elsevier Inc. All rights reserved.

Investigations into the Anti-Felting Properties of Sputtered Wool Using Plasma Treatment

NASA Astrophysics Data System (ADS)

M. Borghei, S.; Shahidi, S.; Ghoranneviss, M.; Abdolahi, Z.

2013-01-01

In this research the effects of mordant and plasma sputtering treatments on the crystallinity and morphological properties of wool fabrics were investigated. The felting behavior of the treated samples was also studied. We used madder as a natural dye and copper sulfate as a metal mordant. We also used copper as the electrode material in a DC magnetron plasma sputtering device. The anti-felting properties of the wool samples before and after dying was studied, and it was shown that the shrink resistance and anti-felting behavior of the wool had been significantly improved by the plasma sputtering treatment. In addition, the percentage of crystallinity and the size of the crystals were investigated using an X-ray diffractometer, and a scanning electron microscope was used for morphological analysis. The amount of copper particles on the surface of the mordanted and sputtered fabrics was studied using the energy dispersive X-ray (EDX) method, and the hydrophobic properties of the samples were examined using the water drop test. The results show that with plasma sputtering treatment, the hydrophobic properties of the surface of wool become super hydrophobic.

Immobilization and release of copper species from a microstructured polypyrrole matrix.

PubMed

González, M B; Brugnoni, L I; Flamini, D O; Quinzani, L M; Saidman, S B

2017-01-01

Copper species immobilization in hollow rectangular-sectioned microtubes of polypyrrole (PPy) electrosynthesized on 316L stainless steel was carried out using two different methods. One of them involved the immobilization after the PPy electropolymerization and the other one during the electrosynthesis process. The electrodes modified with copper species were rotated at different speeds in well water under open-circuit potential conditions. The release of copper species from the PPy matrix and the antibacterial activity against Escherichia coli were analyzed. The obtained results demonstrate that the amount of copper species released as well as the bactericidal effects against E. coli increases with rotation speed. The PPy coating modified with copper species after the electropolymerization reaction exhibited the best performance in terms of antibacterial activity and corrosion protection. These electrodes were tested in a lab-scale continuous flow system for well water disinfection.

Casting copper to tungsten for high-power arc lamp cathodes

NASA Technical Reports Server (NTRS)

Will, H. A.

1974-01-01

Voids forming at interface when copper is cast onto tungsten can be eliminated by adding wetting agent during casting process. Small amount of copper and nickel are cast onto thoriated tungsten insert, insert is recast with more copper to form electrode. Good thermal conductance results in long-lived cathode.

Electroreduction of CO{sub 2} using copper-deposited on boron-doped diamond (BDD)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Panglipur, Hanum Sekar; Ivandini, Tribidasari A., E-mail: ivandini.tri@sci.ui.ac.id; Einaga, Yasuaki

Electroreduction of CO{sub 2} was studied at copper-modified boron-doped diamond (Cu-BDD) electrodes as the working electrode. The Cu-BDD electrodes were prepared by electrochemical reduction with various concentrations of CuSO{sub 4} solutions. FE-SEM was utilized to characterize the electrodes. At Cu-BDD electrodes, a reduction peak at around -1.2 V (vs Ag/AgCl) attributtable to CO{sub 2} reductions could be observed by cyclic voltammetry technique of CO{sub 2} bubbled in water containing 0.1M NaCl. Accordingly, electroreduction of CO{sub 2} was conducted at -1.2 V (vs Ag/AgCl) using amperometry technique. The chemical products of the electroreduction analyzed by using HPLC showed the formation of formaldehyde, formicmore » acid, and acetic acid at Cu-BDD electrodes.« less

New Three-Dimensional Porous Electrode Concept: Vertically-Aligned Carbon Nanotubes Directly Grown on Embroidered Copper Structures

PubMed Central

Amade, Roger; Hussain, Shahzad; Bertran, Enric; Bechtold, Thomas

2017-01-01

New three-dimensional (3D) porous electrode concepts are required to overcome limitations in Li-ion batteries in terms of morphology (e.g., shapes, dimensions), mechanical stability (e.g., flexibility, high electroactive mass loadings), and electrochemical performance (e.g., low volumetric energy densities and rate capabilities). Here a new electrode concept is introduced based on the direct growth of vertically-aligned carbon nanotubes (VA-CNTs) on embroidered Cu current collectors. The direct growth of VA-CNTs was achieved by plasma-enhanced chemical vapor deposition (PECVD), and there was no application of any post-treatment or cleaning procedure. The electrochemical behavior of the as-grown VA-CNTs was analyzed by charge/discharge cycles at different specific currents and with electrochemical impedance spectroscopy (EIS) measurements. The results were compared with values found in the literature. The as-grown VA-CNTs exhibit higher specific capacities than graphite and pristine VA-CNTs found in the literature. This together with the possibilities that the Cu embroidered structures offer in terms of specific surface area, total surface area, and designs provide a breakthrough in new 3D electrode concepts. PMID:29232892

Evolution of Spatial pH Distribution in Aqueous Solution induced by Atmospheric Pressure Plasma

NASA Astrophysics Data System (ADS)

Takahashi, Shigenori; Mano, Kakeru; Hayashi, Yui; Takada, Noriharu; Kanda, Hideki; Goto, Motonobu

2016-09-01

Discharge plasma at gas-liquid interface produces some active species, and then they affect chemical reactions in aqueous solution, where pH of aqueous solution is changed due to redox species. The pH change of aqueous solution is an important factor for chemical reactions. However, spatial pH distribution in a reactor during the discharge has not been clarified yet. Thus, this work focused on spatial pH distribution of aqueous solution when pulsed discharge plasma was generated from a copper electrode in gas phase to aqueous solution in a reactor. Experiments were conducted using positive unipolar pulsed power. The unipolar pulsed voltage at +8.0 kV was applied to the copper electrode and the bottom of the reactor was grounded. The size of the reactor was 80 mm wide, 10 mm deep, and 40 mm high. The electrode was set at distance of 2 mm from the solution surface. Anthocyanins were contained in the aqueous solution as a pH indicator. The change pH solution spread horizontally, and low pH region of 10 mm in depth was formed. After discharge for 10 minutes, the low pH region was diffused toward the bottom of the reactor. After discharge for 60 minutes, the pH of the whole solution decreased.

Method for sputtering with low frequency alternating current

DOEpatents

Timberlake, John R.

1996-01-01

Low frequency alternating current sputtering is provided by connecting a low frequency alternating current source to a high voltage transformer having outer taps and a center tap for stepping up the voltage of the alternating current. The center tap of the transformer is connected to a vacuum vessel containing argon or helium gas. Target electrodes, in close proximity to each other, and containing material with which the substrates will be coated, are connected to the outer taps of the transformer. With an applied potential, the gas will ionize and sputtering from the target electrodes onto the substrate will then result. The target electrodes can be copper or boron, and the substrate can be stainless steel, aluminum, or titanium. Copper coatings produced are used in place of nickel and/or copper striking.

Method for sputtering with low frequency alternating current

DOEpatents

Timberlake, J.R.

1996-04-30

Low frequency alternating current sputtering is provided by connecting a low frequency alternating current source to a high voltage transformer having outer taps and a center tap for stepping up the voltage of the alternating current. The center tap of the transformer is connected to a vacuum vessel containing argon or helium gas. Target electrodes, in close proximity to each other, and containing material with which the substrates will be coated, are connected to the outer taps of the transformer. With an applied potential, the gas will ionize and sputtering from the target electrodes onto the substrate will then result. The target electrodes can be copper or boron, and the substrate can be stainless steel, aluminum, or titanium. Copper coatings produced are used in place of nickel and/or copper striking. 6 figs.

Material for electrodes of low temperature plasma generators

DOEpatents

Caplan, Malcolm; Vinogradov, Sergel Evge'evich; Ribin, Valeri Vasil'evich; Shekalov, Valentin Ivanovich; Rutberg, Philip Grigor'evich; Safronov, Alexi Anatol'evich

2008-12-09

Material for electrodes of low temperature plasma generators. The material contains a porous metal matrix impregnated with a material emitting electrons. The material uses a mixture of copper and iron powders as a porous metal matrix and a Group IIIB metal component such as Y.sub.2O.sub.3 is used as a material emitting electrons at, for example, the proportion of the components, mass %: iron: 3-30; Y.sub.2O.sub.3:0.05-1; copper: the remainder. Copper provides a high level of heat conduction and electric conductance, iron decreases intensity of copper evaporation in the process of plasma creation providing increased strength and lifetime, Y.sub.2O.sub.3 provides decreasing of electronic work function and stability of arc burning. The material can be used for producing the electrodes of low temperature AC plasma generators used for destruction of liquid organic wastes, medical wastes, and municipal wastes as well as for decontamination of low level radioactive waste, the destruction of chemical weapons, warfare toxic agents, etc.

Material for electrodes of low temperature plasma generators

DOEpatents

Caplan, Malcolm; Vinogradov, Sergel Evge'evich; Ribin, Valeri Vasil'evich; Shekalov, Valentin Ivanovich; Rutberg, Philip Grigor'evich; Safronov, Alexi Anatol'evich; Shiryaev, Vasili Nikolaevich

2010-03-02

Material for electrodes of low temperature plasma generators. The material contains a porous metal matrix impregnated with a material emitting electrons. The material uses a mixture of copper and iron powders as a porous metal matrix and a Group IIIB metal component such as Y.sub.2O.sub.3 is used as a material emitting electrons at, for example, the proportion of the components, mass %: iron:3-30; Y.sub.2O.sub.3:0.05-1; copper: the remainder. Copper provides a high level of heat conduction and electric conductance, iron decreases intensity of copper evaporation in the process of plasma creation providing increased strength and lifetime, Y.sub.2O.sub.3 provides decreasing of electronic work function and stability of arc burning. The material can be used for producing the electrodes of low temperature AC plasma generators used for destruction of liquid organic wastes, medical wastes, municipal wastes as well as for decontamination of low level radioactive waste, the destruction of chemical weapons, warfare toxic agents, etc.

Chemical synthesis of flower-like hybrid Cu(OH)2/CuO electrode: Application of polyvinyl alcohol and triton X-100 to enhance supercapacitor performance.

PubMed

Shinde, S K; Fulari, V J; Kim, D-Y; Maile, N C; Koli, R R; Dhaygude, H D; Ghodake, G S

2017-08-01

In this research article, we report hybrid nanomaterials of copper hydroxide/copper oxide (Cu(OH) 2 /CuO). A thin films were prepared by using a facile and cost-effective successive ionic layer adsorption and reaction (SILAR) method. As-synthesized and hybrid Cu(OH) 2 /CuO with two different surfactants polyvinyl alcohol (PVA) and triton-X 100 (TRX-100) was prepared having distinct morphological, structural, and supercapacitor properties. The surface of the thin film samples were examined by scanning electron microscopy (SEM). A nanoflower-like morphology of the Cu(OH) 2 /CuO nanostructures arranged vertically was evidenced on the stainless steel substrate. The surface was well covered by nanoflake-like morphology and formed a uniform Cu(OH) 2 /CuO nanostructures after treating with surfactants. X-ray diffraction patterns were used to confirm the hybrid phase of Cu(OH) 2 /CuO materials. The electrochemical properties of the pristine Cu(OH) 2 /CuO, PVA:Cu(OH) 2 /CuO, TRX-100:Cu(OH) 2 /CuO films were observed by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy technique. The electrochemical examination reveals that the Cu(OH) 2 /CuO electrode has excellent specific capacitance, 292, 533, and 443Fg -1 with pristine, PVA, and TRX-100, respectively in 1M Na 2 SO 4 electrolyte solution. The cyclic voltammograms (CV) of Cu(OH) 2 /CuO electrode shows positive role of the PVA and TRX-100 to enhance supercapacitor performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Non-electrolytic synthesis of copper oxide/carbon nanocomposite by surface plasma in super-dehydrated ethanol

NASA Astrophysics Data System (ADS)

Kozak, Dmytro S.; Sergiienko, Ruslan A.; Shibata, Etsuro; Iizuka, Atsushi; Nakamura, Takashi

2016-02-01

Electrolytic processes are widely used to synthesize different nanomaterials and it does not depend on what kind of the method has been applied (wet-chemistry, sonochemistry, plasma chemistry, electrolysis and so on). Generally, the reactions in the electrolyte are considered to be reduction/oxidation (REDOX) reactions between chemical reagents or the deposition of matter on the electrodes, in line with Faraday’s law. Due to the presence of electroconductive additives in any electrolyte, the polarization effect of polar molecules conducting an electrical current disappears, when external high-strength electric field is induced. Because initially of the charge transfer always belongs of electroconductive additive and it does not depend on applied voltage. The polarization of ethanol molecules has been applied to conduct an electric current by surface plasma interaction for the synthesis of a copper oxide/carbon nanocomposite material.

Control of Compact-Toroid Characteristics by External Copper Shell

NASA Astrophysics Data System (ADS)

Matsumoto, T.; Sekiguchi, J.; Asai, T.; Gota, H.; Roche, T.; Allfrey, I.; Cordero, M.; Garate, E.; Kinley, J.; Valentine, T.; Waggoner, W.; the TAE Team

2015-11-01

A collaborative research project by Tri Alpha Energy and Nihon University has been conducted for several years, which led to the development of a new compact toroid (CT) injector for efficient FRC particle refueling in the C-2U experiment. The CT is formed by a magnetized coaxial plasma gun (MCPG), consisting of coaxial cylindrical electrodes. In CT formation via MCPG, the magnetic helicity content of the generated CT is one of the critical parameters. A bias coil is inserted into the inner electrode to generate a poloidal flux. The resultant bias magnetic field is spread out of MCPG with time due to its low-frequency bias current. To obtain a more effectively distributed bias magnetic field as well as to improve the voltage breakdown between electrodes, the MCPG incorporates a novel ~ 1 mm thick copper shell mounted outside of the outer electrode. This allows for reliable and controlled operation and more robust CT generation. A detailed discussion of the copper shell and experimental test results will be presented.

Hollow nanostructures of metal oxides as next generation electrode materials for supercapacitors.

PubMed

Sharma, Vikas; Singh, Inderjeet; Chandra, Amreesh

2018-01-22

Hollow nanostructures of copper oxides help to stabilize appreciably higher electrochemical characteristics than their solid counter parts of various morphologies. The specific capacitance values, calculated using cyclic voltammetry (CV) and charge-discharge (CD) studies, are found to be much higher than the values reported in literature for copper oxide particles showing  intriguing morphologies or even composites with trendy systems like CNTs, rGO, graphene, etc. The proposed cost-effective synthesis route makes these materials industrially viable for application in alternative energy storage devices. The improved electrochemical response can be attributed to effective access to the higher number of redox sites that become available on the surface, as well as in the cavity of the hollow particles. The ion transport channels also facilitate efficient de-intercalation, which results in the enhancement of cyclability and Coulombic efficiency. The charge storage mechanism in copper oxide structures is also proposed in the paper.

ELECTROLYSIS AND ION EXCHANGE FOR THE IN PROCESS RECYCLING OF COPPER FROM SEMI-CONDUCTOR PROCESSING SOLUTIONS

EPA Science Inventory

The objectives of the study are to develop an understanding of the electrodeposition of copper onto extended-area electrodes, and of the adsorption/desorption of copper onto ion exchange resins with a high affinity for copper. The principles elucidated in this work will pave the ...

Shapes of Spectral Lines of Nonuniform Plasma of Electric Arc Discharge Between Copper Electrodes

NASA Astrophysics Data System (ADS)

Babich, Ida L.; Boretskij, Viacheslav F.; Veklich, Anatoly N.

2007-09-01

The radial profiles of the temperature and electron density in the plasma of the free burning electric arc between copper electrodes are studied by optical spectroscopy techniques. The electron density and the temperature in plasma as initial parameters were used in the calculation of the plasma composition in local thermodynamic equilibrium (LTE) assumption. We used the Saha's equation for copper, nitrogen and oxygen, dissociation equation for nitrogen and oxygen, the equation of plasma electrical neutrality and Dalton's law as well. So, it would be possible to determine the amounts of metal vapours in plasma.

High performance zinc anode for battery applications

NASA Technical Reports Server (NTRS)

Casey, John E., Jr. (Inventor)

1998-01-01

An improved zinc anode for use in a high density rechargeable alkaline battery is disclosed. A process for making the zinc electrode comprises electrolytic loading of the zinc active material from a slightly acidic zinc nitrate solution into a substrate of nickel, copper or silver. The substrate comprises a sintered plaque having very fine pores, a high surface area, and 80-85 percent total initial porosity. The residual porosity after zinc loading is approximately 25-30%. The electrode of the present invention exhibits reduced zinc mobility, shape change and distortion, and demonstrates reduced dendrite buildup cycling of the battery. The disclosed battery is useful for applications requiring high energy density and multiple charge capability.

Increased sensitivity of anodic stripping voltammetry at the hanging mercury drop electrode by ultracathodic deposition.

PubMed

Rodrigues, José A; Rodrigues, Carlos M; Almeida, Paulo J; Valente, Inês M; Gonçalves, Luís M; Compton, Richard G; Barros, Aquiles A

2011-09-09

An improved approach to the anodic stripping voltammetric (ASV) determination of heavy metals, using the hanging mercury drop electrode (HMDE), is reported. It was discovered that using very cathodic accumulation potentials, at which the solvent reduction occurs (overpotential deposition), the voltammetric signals of zinc(II), cadmium(II), lead(II) and copper(II) increase. When compared with the classical methodology a 5 to 10-fold signal increase is obtained. This effect is likely due to both mercury drop oscillation at such cathodic potentials and added local convection at the mercury drop surface caused by the evolution of hydrogen bubbles. Copyright © 2011 Elsevier B.V. All rights reserved.

Epitaxial-Growth-Induced Junction Welding of Silver Nanowire Network Electrodes.

PubMed

Kang, Hyungseok; Song, Sol-Ji; Sul, Young Eun; An, Byeong-Seon; Yin, Zhenxing; Choi, Yongsuk; Pu, Lyongsun; Yang, Cheol-Woong; Kim, Youn Sang; Cho, Sung Min; Kim, Jung-Gu; Cho, Jeong Ho

2018-05-22

In this study, we developed a roll-to-roll Ag electroplating process for metallic nanowire electrodes using a galvanostatic mode. Electroplating is a low-cost and facile method for deposition of metal onto a target surface with precise control of both the composition and the thickness. Metallic nanowire networks [silver nanowires (AgNWs) and copper nanowires (CuNWs)] coated onto a polyethylene terephthalate (PET) film were immersed directly in an electroplating bath containing AgNO 3 . Solvated silver ions (Ag + ions) were deposited onto the nanowire surface through application of a constant current via an external circuit between the nanowire networks (cathode) and a Ag plate (anode). The amount of electroplated Ag was systematically controlled by changing both the applied current density and the electroplating time, which enabled precise control of the sheet resistance and optical transmittance of the metallic nanowire networks. The optimized Ag-electroplated AgNW (Ag-AgNW) films exhibited a sheet resistance of ∼19 Ω/sq at an optical transmittance of 90% (550 nm). A transmission electron microscopy study confirmed that Ag grew epitaxially on the AgNW surface, but a polycrystalline Ag structure was formed on the CuNW surface. The Ag-electroplated metallic nanowire electrodes were successfully applied to various electronic devices such as organic light-emitting diodes, triboelectric nanogenerators, and a resistive touch panel. The proposed roll-to-roll Ag electroplating process provides a simple, low-cost, and scalable method for the fabrication of enhanced transparent conductive electrode materials for next-generation electronic devices.

Determination of Zinc, Cadmium, Lead, Copper and Silver Using a Carbon Paste Electrode and a Screen Printed Electrode Modified with Chromium(III) Oxide

PubMed Central

Koudelkova, Zuzana; Syrovy, Tomas; Ambrozova, Pavlina; Moravec, Zdenek; Kubac, Lubomir; Hynek, David; Adam, Vojtech

2017-01-01

In this study, the preparation and electrochemical application of a chromium(III) oxide modified carbon paste electrode (Cr-CPE) and a screen printed electrode (SPE), made from the same material and optimized for the simple, cheap and sensitive simultaneous determination of zinc, cadmium, lead, copper and the detection of silver ions, is described. The limits of detection and quantification were 25 and 80 µg·L−1 for Zn(II), 3 and 10 µg·L−1 for Cd(II), 3 and 10 µg·L−1 for Pb(II), 3 and 10 µg·L−1 for Cu(II), and 3 and 10 µg·L−1 for Ag(I), respectively. Furthermore, this promising modification was transferred to the screen-printed electrode. The limits of detection for the simultaneous determination of zinc, cadmium, copper and lead on the screen printed electrodes were found to be 350 µg·L−1 for Zn(II), 25 µg·L−1 for Cd(II), 3 µg·L−1 for Pb(II) and 3 µg·L−1 for Cu(II). Practical usability for the simultaneous detection of these heavy metal ions by the Cr-CPE was also demonstrated in the analyses of wastewaters. PMID:28792450

Determination of Zinc, Cadmium, Lead, Copper and Silver Using a Carbon Paste Electrode and a Screen Printed Electrode Modified with Chromium(III) Oxide.

PubMed

Koudelkova, Zuzana; Syrovy, Tomas; Ambrozova, Pavlina; Moravec, Zdenek; Kubac, Lubomir; Hynek, David; Richtera, Lukas; Adam, Vojtech

2017-08-09

In this study, the preparation and electrochemical application of a chromium(III) oxide modified carbon paste electrode (Cr-CPE) and a screen printed electrode (SPE), made from the same material and optimized for the simple, cheap and sensitive simultaneous determination of zinc, cadmium, lead, copper and the detection of silver ions, is described. The limits of detection and quantification were 25 and 80 µg·L -1 for Zn(II), 3 and 10 µg·L -1 for Cd(II), 3 and 10 µg·L -1 for Pb(II), 3 and 10 µg·L -1 for Cu(II), and 3 and 10 µg·L -1 for Ag(I), respectively. Furthermore, this promising modification was transferred to the screen-printed electrode. The limits of detection for the simultaneous determination of zinc, cadmium, copper and lead on the screen printed electrodes were found to be 350 µg·L -1 for Zn(II), 25 µg·L -1 for Cd(II), 3 µg·L -1 for Pb(II) and 3 µg·L -1 for Cu(II). Practical usability for the simultaneous detection of these heavy metal ions by the Cr-CPE was also demonstrated in the analyses of wastewaters.

Nanomolar Trace Metal Analysis of Copper at Gold Microband Arrays

NASA Astrophysics Data System (ADS)

Wahl, A.; Dawson, K.; Sassiat, N.; Quinn, A. J.; O'Riordan, A.

2011-08-01

This paper describes the fabrication and electrochemical characterization of gold microband electrode arrays designated as a highly sensitive sensor for trace metal detection of copper in drinking water samples. Gold microband electrodes have been routinely fabricated by standard photolithographic methods. Electrochemical characterization were conducted in 0.1 M H2SO4 and found to display characteristic gold oxide formation and reduction peaks. The advantages of gold microband electrodes as trace metal sensors over currently used methods have been investigated by employing under potential deposition anodic stripping voltammetry (UPD-ASV) in Cu2+ nanomolar concentrations. Linear correlations were observed for increasing Cu2+ concentrations from which the concentration of an unknown sample of drinking water was estimated. The results obtained for the estimation of the unknown trace copper concentration in drinking was in good agreement with expected values.

Amperometric sensing of hydrogen peroxide using glassy carbon electrode modified with copper nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sophia, J.; Muralidharan, G., E-mail: muraligru@gmail.com

2015-10-15

In this paper, fabrication of glassy carbon electrode (GCE) modified with nano copper particles is discussed. The modified electrode has been tested for the non-enzymatic electrochemical detection of hydrogen peroxide (H{sub 2}O{sub 2}). The copper nanoparticles (Cu NPs) were prepared employing a simple chemical reduction method. The presence of Cu NPs was confirmed through UV–visible (UV–vis) absorption spectroscopy and X-ray diffraction (XRD) analysis. The size and morphology of the particles were investigated using transmission electron microscopy (TEM). The electrochemical properties of the fabricated sensor were studied via cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS). The electrochemical sensor displayedmore » excellent performance features towards H{sub 2}O{sub 2} detection exhibiting wide linear range, low detection limit, swift response time, good reproducibility and stability.« less

Cementation of colloidal particles on electrodes in a galvanic microreactor.

PubMed

Jan, Linda; Punckt, Christian; Aksay, Ilhan A

2013-07-10

We have studied the processes leading to the cementation of colloidal particles during their autonomous assembly on corroding copper electrodes within a Cu-Au galvanic microreactor. We determined the onset of particle immobilization through particle tracking, monitored the dissolution of copper as well as the deposition of insoluble products of the corrosion reactions in situ, and showed that particle immobilization initiated after reaction products (RPs) began to deposit on the electrode substrate. We further demonstrated that the time and the extent of RP precipitation and thus the strength of the particle-substrate bond could be tuned by varying the amount of copper in the system and the microreactor pH. The ability to cement colloidal particles at locations undergoing corrosion illustrates that the studied colloidal assembly approach holds potential for applications in dynamic material property adaptation.

Polymer-grafted QCM chemical sensor and application to heavy metalions real time detection.

PubMed

Sartore, Luciana; Barbaglio, Marzia; Borgese, Laura; Bontempi, Elza

2011-07-20

A flow type quartz crystal microbalance (QCM) chemical sensor was developed for monitoring of heavy metal ions in aqueous solutions (that is suitable for environmental monitoring). The sensor is based upon surface chelation of the metal ions at multifunctional polymer modified gold electrodes on 9 MHz AT-cut quartz resonators, functioning as a QCM. New processes have been developed which enable to obtain surface-modified gold electrodes with high heavy metal ions complexing ability. These polymer grafted QCM sensors can selectively adsorb heavy metal ions, such as copper lead chrome and cadmium, from solution over a wide range from 0.01 to 1000 ppm concentration by complexation with functional groups in the polymers. Cations typically present in natural water did not interfere with the detection of heavy metals. X-Ray Reflectivity (XRR) and Total Reflection X-ray Fluorescence (TXRF) were carried out to characterise the unmodified and modified gold surfaces as well as to verify the possibility to selectively bond and remove metal ions.

Modeling of breakdown during the post-arc phase of a vacuum circuit breaker

NASA Astrophysics Data System (ADS)

Sarrailh, P.; Garrigues, L.; Boeuf, J. P.; Hagelaar, G. J. M.

2010-12-01

After a high-current interruption in a vacuum circuit breaker (VCB), the electrode gap is filled with a high density copper vapor plasma in a large copper vapor density (~1022 m-3). The copper vapor density is sustained by electrode evaporation. During the post-arc phase, a rapidly increasing voltage is applied to the gap, and a sheath forms and expands, expelling the plasma from the gap when circuit breaking is successful. There is, however, a risk of breakdown during that phase, leading to the failure of the VCB. Preventing breakdown during the post-arc phase is an important issue for the improvement of VCB reliability. In this paper, we analyze the risk of Townsend breakdown in the high copper vapor density during the post-arc phase using a numerical model that takes into account secondary electron emission, volume ionization, and plasma and neutral transport, for given electrode temperatures. The simulations show that fast neutrals created in the cathode sheath by charge exchange collisions with ions generate a very large secondary electron emission current that can lead to Townsend breakdown. The results also show that the risk of failure of the VCB due to Townsend breakdown strongly depends on the electrode temperatures (which govern the copper vapor density) and becomes important for temperatures greater than 2100 K, which can be reached in vacuum arcs. The simulations also predict that a hotter anode tends to increase the risk of Townsend breakdown.

Measurement of labile copper in wine by medium exchange stripping potentiometry utilising screen printed carbon electrodes.

PubMed

Clark, Andrew C; Kontoudakis, Nikolaos; Barril, Celia; Schmidtke, Leigh M; Scollary, Geoffrey R

2016-07-01

The presence of copper in wine is known to impact the reductive, oxidative and colloidal stability of wine, and techniques enabling measurement of different forms of copper in wine are of particular interest in understanding these spoilage processes. Electrochemical stripping techniques developed to date require significant pretreatment of wine, potentially disturbing the copper binding equilibria. A thin mercury film on a screen printed carbon electrode was utilised in a flow system for the direct analysis of labile copper in red and white wine by constant current stripping potentiometry with medium exchange. Under the optimised conditions, including an enrichment time of 500s and constant current of 1.0μA, the response range was linear from 0.015 to 0.200mg/L. The analysis of 52 red and white wines showed that this technique generally provided lower labile copper concentrations than reported for batch measurement by related techniques. Studies in a model system and in finished wines showed that the copper sulfide was not measured as labile copper, and that loss of hydrogen sulfide via volatilisation induced an increase in labile copper within the model wine system. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrochemical synthesis of copper nanoparticles using cuprous oxide as a precursor in choline chloride-urea deep eutectic solvent: nucleation and growth mechanism.

PubMed

Zhang, Q B; Hua, Y X

2014-12-28

The electrochemical nucleation and growth kinetics of copper nanoparticles on a Ni electrode have been studied with cyclic voltammetry and chronoamperometry in the choline chloride (ChCl)-urea based deep eutectic solvent (DES). The copper source was introduced into the solvent by the dissolution of Cu(I) oxide (Cu2O). Cyclic voltammetry indicates that the electroreduction of Cu(I) species in the DES is a diffusion-controlled quasi-reversible process. The analysis of the chronoamperometric transient behavior during electrodeposition suggests that the deposition of copper on the Ni electrode at low temperatures follows a progressive nucleation and three-dimensional growth controlled by diffusion. The effect of temperature on the diffusion coefficient of Cu(I) species that is present in the solvent and electron transfer rate constant obeys the Arrhenius law, according to which the activation energies are estimated to be 49.20 and 21.72 kJ mol(-1), respectively. The initial stage of morphological study demonstrates that both electrode potential and temperature play important roles in controlling the nucleation and growth kinetics of the nanocrystals during the electrodeposition process. Electrode potential is observed to affect mainly the nucleation process, whereas temperature makes a major contribution to the growth process.

Lead zirconate titanate thin films directly on copper electrodes for ferroelectric, dielectric and piezoelectric applications

NASA Astrophysics Data System (ADS)

Kingon, Angus I.; Srinivasan, Sudarsan

2005-03-01

Replacement of noble metal electrodes by base metals significantly lowers the cost of ferroelectric, piezoelectric and dielectric devices. Here, we demonstrate that it is possible to process lead zirconate (Pb(Zr0.52Ti0.48)O3, or PZT) thin films directly on base metal copper foils. We explore the impact of the oxygen partial pressure during processing, and demonstrate that high-quality films and interfaces can be achieved through control of the oxygen partial pressure within a narrow window predicted by thermodynamic stability considerations. This demonstration has broad implications, opening up the possibility of the use of low-cost, high-conductivity copper electrodes for a range of Pb-based perovskite materials, including PZT films in embedded printed circuit board applications for capacitors, varactors and sensors; multilayer PZT piezoelectric stacks; and multilayer dielectric and electrostrictive devices based on lead magnesium niobate-lead titanate. We also point out that the capacitors do not fatigue on repeated switching, unlike those with Pt noble metal electrodes. Instead, they appear to be fatigue-resistant, like capacitors with oxide electrodes. This may have implications for ferroelectric non-volatile memories.

Copper-Based Electrochemical Sensor with Palladium Electrode for Cathodic Stripping Voltammetry of Manganese

PubMed Central

2015-01-01

In this work, we report on the development of a palladium-based, microfabricated point-of-care electrochemical sensor for the determination of manganese using square wave cathodic stripping voltammetry. Heavy metals require careful monitoring, yet current methods are too complex for a point-of-care system. Voltammetry offers an attractive approach to metal detection on the microscale, but traditional carbon, gold, or platinum electrodes are difficult or expensive to microfabricate, preventing widespread use. Our sensor uses palladium working and auxiliary electrodes and integrates them with a copper-based reference electrode for simple fabrication and compatibility with microfabrication and printed circuit board processing, while maintaining competitive performance in electrochemical detection. Copper electrodes were prepared on glass substrate using a combination of microfabrication procedures followed by electrodeposition of palladium. The disposable sensor system was formed by bonding a poly(dimethylsiloxane) (PDMS) well to the glass substrate. Cathodic stripping voltammetry of manganese using our new disposable palladium-based sensors exhibited 334 nM (18.3 ppb) limit of detection in borate buffer. The sensor was used to demonstrate manganese determination in natural water samples from a pond in Burnet Woods, located in Cincinnati, OH, and the Ohio River. PMID:25476591

Copper-based electrochemical sensor with palladium electrode for cathodic stripping voltammetry of manganese.

PubMed

Kang, Wenjing; Pei, Xing; Bange, Adam; Haynes, Erin N; Heineman, William R; Papautsky, Ian

2014-12-16

In this work, we report on the development of a palladium-based, microfabricated point-of-care electrochemical sensor for the determination of manganese using square wave cathodic stripping voltammetry. Heavy metals require careful monitoring, yet current methods are too complex for a point-of-care system. Voltammetry offers an attractive approach to metal detection on the microscale, but traditional carbon, gold, or platinum electrodes are difficult or expensive to microfabricate, preventing widespread use. Our sensor uses palladium working and auxiliary electrodes and integrates them with a copper-based reference electrode for simple fabrication and compatibility with microfabrication and printed circuit board processing, while maintaining competitive performance in electrochemical detection. Copper electrodes were prepared on glass substrate using a combination of microfabrication procedures followed by electrodeposition of palladium. The disposable sensor system was formed by bonding a poly(dimethylsiloxane) (PDMS) well to the glass substrate. Cathodic stripping voltammetry of manganese using our new disposable palladium-based sensors exhibited 334 nM (18.3 ppb) limit of detection in borate buffer. The sensor was used to demonstrate manganese determination in natural water samples from a pond in Burnet Woods, located in Cincinnati, OH, and the Ohio River.

Electrodeposition in microgravity: Ground-based experiments

NASA Technical Reports Server (NTRS)

Riley, C.; Coble, H. D.

1982-01-01

Electrodeposition was studied at one-hundreth g and compared with bench studies at 1 g. The low gravity was achieved during KC-135 aircraft parobolic flights. Flow in a simple cobalt cell (1 M CoSO4) operating under typical commercial conditions (10 to 20 mA/sq cm and 1 V) was monitored with a Schlieren optical system. Natural convection was absent at one-hundreth g. Quantitative comparisons on a cobalt cell with shielded electrodes using interferometry were carried out. Fringe shift differences indicate greater semi-infinite linear diffusion at 1 g than at one-hundreth g for cobalt. Since a shielded electrode operates under diffusion controlled conditions, no differences between 1 g and one-hundreth g would be expected. Similar comparisons on a shielded electrode copper cell were inconclusive. Bench codeposition experiments using polystyrene neutral buoyancy particles coupled with a shielded electrode cobalt cell were begun. Tracking of 12 micron particles showed no measurable difference between thermal/Brownian motion when the cell was operational or nonoperational. Initial experiments on codeposition quality showed a strong dependence upon cathode surface preparation in a shielded electrode configuration.

Investigation of the degradation of different nickel anode types for alkaline fuel cells (AFCs)

NASA Astrophysics Data System (ADS)

Gülzow, E.; Schulze, M.; Steinhilber, G.

Alkaline fuel cells (AFCs) have the opportunity of becoming important for mobile energy systems as, in contrast to other low temperature fuel cells, the alkaline type requires neither noble metal catalysts nor an expensive polymer electrolyte. In AFCs, nickel is used as anode catalyst in gas diffusion electrodes. The metal catalyst was mixed with polytetraflourethylene (PTFE) as organic binder in a knife mile and rolled onto a metal web in a calendar to prepare the electrode. After an activation process with hydrogen evolution at 5 mA/cm 2 for 18 h, the electrodes were stressed at constant loading in a half cell equipment. During the fuel cell operation, the electrochemical performance decreased due to changes of the polymer (PTFE) and of the metal particles in the electrode, which is described in detail in another paper. In this study, three types of electrodes were investigated. The first type of electrode is composed of pure Raney-nickel and PTFE powder, the nickel particles in the second electrode type were selected according to particle size and in the third electrode copper powder was added to the nickel powder not selected by size. The size selected nickel particles show a better electrochemical performance related to the non-selected catalyst, but due to the electrochemically induced disintegration of the nickel particles the electrochemical performance decreases stronger. The copper powder in the third electrode is added to improve the electronic conductivity of the nickel catalyst, but the copper is not stable under the electrochemical conditions in fuel cell operation. With all three anode types long-term experiments have been performed. The electrodes have been characterized after the electrochemical stressing to investigate the degradation processes.

Electrochemical determination of 2,4,6-trinitrophenol using a hybrid film composed of a copper-based metal organic framework and electroreduced graphene oxide.

PubMed

Wang, Yong; Cao, Wei; Wang, Luyao; Zhuang, Qianfen; Ni, Yongnian

2018-06-04

A metal organic framework (MOF) of the type copper(II)-1,3,5-benzenetricarboxylic acid (Cu-BTC) was electrodeposited on electroreduced graphene oxide (ERGO) placed on a glassy carbon electrode (GCE). The modified GCE was used for highly sensitive electrochemical determination of 2,4,6-trinitrophenol (TNP). The fabrication process of the modified electrode was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. Differential pulse voltammetry (DPV) demonstrates that the Cu-BTC/ERGO/GCE gives stronger signals for TNP reduction than Cu-BTC/GCE or ERGO/GCE alone. DPV also shows TNP to exhibit three reduction peaks, the first at a potential of -0.42 V (vs. SCE). This potential was selected because the other three similarly-structured compounds (2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol) do not give a signal at this potential. Response is linear in the 0.2 to 10 μM TNP concentration range, with a 0.1 μM detection limit (at S/N = 3) and a 15.98 μA∙μM -1 ∙cm -2 sensitivity under optimal conditions. The applicability of the sensor was evaluated by detecting TNP in spiked tap water and lake water samples. Recoveries ranged between 95 and 101%. Graphical abstract Schematic presentation of an electrochemical sensor that was fabricated by electrodeposition of the metal-organic framework (MOF) of copper(II)-1,3,5-benzenetricarboxylic acid (Cu-BTC) onto the surface of electroreduced graphene oxide (ERGO) modified glassy carbon electrode (GCE). It was applied to sensitive and selective detection of 2,4,6-trinitrophenol (TNP).

Flexible polypyrrole/copper sulfide/bacterial cellulose nanofibrous composite membranes as supercapacitor electrodes.

PubMed

Peng, Shuo; Fan, Lingling; Wei, Chengzhuo; Liu, Xiaohong; Zhang, Hongwei; Xu, Weilin; Xu, Jie

2017-02-10

Polypyrrole (PPy) and copper sulfide (CuS) have been successfully deposited on bacterial cellulose (BC) membranes to prepare nanofibrous composite electrodes of PPy/CuS/BC for flexible supercapacitor applications. The introduction of CuS remarkably improves the specific capacitance and cycling stability of BC-based electrodes. The specific capacitance of the supercapacitors based on the PPy/CuS/BC electrodes can reach to about 580Fg -1 at a current density of 0.8mAcm -2 and can retain about 73% of their initial value after 300 cycles, while the PPy/BC-based device could retain only 21.7% after 300 cycles. This work provides a promising approach to fabricate cost-effective and flexible nanofibrous composite membranes for high-performance supercapacitor electrodes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Study on effect of tool electrodes on surface finish during electrical discharge machining of Nitinol

NASA Astrophysics Data System (ADS)

Sahu, Anshuman Kumar; Chatterjee, Suman; Nayak, Praveen Kumar; Sankar Mahapatra, Siba

2018-03-01

Electrical discharge machining (EDM) is a non-traditional machining process which is widely used in machining of difficult-to-machine materials. EDM process can produce complex and intrinsic shaped component made of difficult-to-machine materials, largely applied in aerospace, biomedical, die and mold making industries. To meet the required applications, the EDMed components need to possess high accuracy and excellent surface finish. In this work, EDM process is performed using Nitinol as work piece material and AlSiMg prepared by selective laser sintering (SLS) as tool electrode along with conventional copper and graphite electrodes. The SLS is a rapid prototyping (RP) method to produce complex metallic parts by additive manufacturing (AM) process. Experiments have been carried out varying different process parameters like open circuit voltage (V), discharge current (Ip), duty cycle (τ), pulse-on-time (Ton) and tool material. The surface roughness parameter like average roughness (Ra), maximum height of the profile (Rt) and average height of the profile (Rz) are measured using surface roughness measuring instrument (Talysurf). To reduce the number of experiments, design of experiment (DOE) approach like Taguchi’s L27 orthogonal array has been chosen. The surface properties of the EDM specimen are optimized by desirability function approach and the best parametric setting is reported for the EDM process. Type of tool happens to be the most significant parameter followed by interaction of tool type and duty cycle, duty cycle, discharge current and voltage. Better surface finish of EDMed specimen can be obtained with low value of voltage (V), discharge current (Ip), duty cycle (τ) and pulse on time (Ton) along with the use of AlSiMg RP electrode.

Localized etching of an insulator film coated on a copper wire using an atmospheric-pressure microplasma jet.

PubMed

Yoshiki, Hiroyuki

2007-04-01

Atmospheric-pressure microplasma jets (APmicroPJs) of Ar and ArO(2) gases were generated from the tip of a stainless steel surgical needle having outer and inner diameters of 0.4 and 0.2 mm, respectively, with a rf excitation of 13.56 MHz. The steel needle functions both as a powered electrode and a gas nozzle. The operating power is 1.2-6 W and the corresponding peak-to-peak voltage Vp.p. is about 1.5 kV. The APmicroPJ was applied to the localized etching of a polyamide-imide insulator film (thickness of 10 microm) of a copper winding wire of 90 microm diameter. The insulator film around the copper wire was completely removed by the irradiated plasma from a certain direction without fusing the wire. The removal time under the Ar APmicroPJ irradiation was only 3 s at a rf power of 4 W. Fluorescence microscopy and scanning electron microscope images reveal that good selectivity of the insulator film to the copper wire was achieved. In the case of ArO(2) APmicroPJ irradiation with an O(2) concentration of 10% or more, the removed copper surface was converted to copper monoxide CuO.

Enhanced photoelectrocatalytic decomposition of copper cyanide complexes and simultaneous recovery of copper with a Bi2MoO6 electrode under visible light by EDTA/K4P2O7.

PubMed

Zhao, Xu; Zhang, Juanjuan; Qiao, Meng; Liu, Huijuan; Qu, Jiuhui

2015-04-07

Simultaneous photoelectrocatalytic (PEC) oxidation of cyanides and recovery of copper in a PEC reactor with a Bi(2)MoO(6) photoanode was investigated at alkaline conditions under visible light irradiation. The surface variation of the Bi(2)MoO(6) photoanode and titanium cathode was characterized. The Cu mass distribution onto the anode, in the solution, and onto the cathode was fully investigated. In the individual PEC oxidation of copper cyanides, the formation of a black copper oxide on the anode occurred. By keeping the initial cyanide concentration at 0.01 mM, the effect of EDTA/K(4)P(2)O(7) was examined at different molar ratios of EDTA/K(4)P(2)O(7) to cyanide. It was indicated that the oxidation of cyanides increased and simultaneous copper electrodeposition with zero value onto the cathode was feasible at pH 11. Under the optimal conditions, the total cyanide concentration was lowered from 250 to 5.0 mg/L, and the Cu recovery efficiency deposited onto the cathode was higher than 90%. Cyanate was the only product. The role of the photogenerated hole in the oxidation of cyanide ions was confirmed.

Plasma Torch for Plasma Ignition and Combustion of Coal

NASA Astrophysics Data System (ADS)

Ustimenko, Alexandr; Messerle, Vladimir

2015-09-01

Plasma-fuel systems (PFS) have been developed to improve coal combustion efficiency. PFS is a pulverized coal burner equipped with arc plasma torch producing high temperature air stream of 4000 - 6000 K. Plasma activation of coal at the PFS increases the coal reactivity and provides more effective ignition and ecologically friendly incineration of low-rank coal. The main and crucial element of PFS is plasma torch. Simplicity and reliability of the industrial arc plasma torches using cylindrical copper cathode and air as plasma forming gas predestined their application at heat and power engineering for plasma aided coal combustion. Life time of these plasma torches electrodes is critical and usually limited to 200 hours. Considered in this report direct current arc plasma torch has the cathode life significantly exceeded 1000 hours. To ensure the electrodes long life the process of hydrocarbon gas dissociation in the electric arc discharge is used. In accordance to this method atoms and ions of carbon from near-electrode plasma deposit on the active surface of the electrodes and form electrode carbon condensate which operates as ``actual'' electrode. Complex physicochemical investigation showed that deposit consists of nanocarbon material.

Determination of trace arsenic on hanging copper amalgam drop electrode.

PubMed

Piech, Robert; Baś, Bogusław; Niewiara, Ewa; Kubiak, Władysław W

2007-04-30

Hanging copper amalgam drop electrode has been applied for trace determination of arsenic by cathodic stripping analysis. Detection limit for As(III) as low as 0.33nM (0.02mug/L) at deposition time (240s) could be obtained. For seven successive determinations of As(III) at concentration of 5nM relative standard deviation was 2.5% (n=7). Interferences from selected metals and surfactant substances were examined. Absence of copper ions in sample solution causes easier optimization and makes method less vulnerable on contamination. The developed method was validated by analysis of certified reference materials (CRMs) and applied to arsenic determinations in natural water samples.

Experimental study of the electrode material for electro-osmosis in mudflat sludge

NASA Astrophysics Data System (ADS)

Liu, Yi-min; Xu, Hao-feng

2017-11-01

In order to study the performance of electro-osmosis, several tests including indoor electro-osmosis experiments using copper, aluminum as the anode and cathode electrode materials, and Mercury Intrusion Porosimiter (MIP) were conducted. The results indicate that the drainage ratio using aluminum is faster than that of copper while the energy consumption per unit is lower, the effectiveness is better than that of copper. After electro-osmosis, the percentage of pore with large diameter shows a remarkable decrease comparing with the remolded soil which result in the increase of pore with small diameter. The reasons were discussed in this paper.

Effect of enzymatic orientation through the use of syringaldazine molecules on multiple multi-copper oxidase enzymes.

PubMed

Ulyanova, Yevgenia; Babanova, Sofia; Pinchon, Erica; Matanovic, Ivana; Singhal, Sameer; Atanassov, Plamen

2014-07-14

The effect of proper enzyme orientation at the electrode surface was explored for two multi-copper oxygen reducing enzymes: Bilirubin Oxidase (BOx) and Laccase (Lac). Simultaneous utilization of "tethering" agent (1-pyrenebutanoic acid, succinimidyl ester; PBSE), for stable enzyme immobilization, and syringaldazine (Syr), for enzyme orientation, of both Lac and BOx led to a notable enhancement of the electrode performance. For Lac cathodes tested in solution it was established that PBSE-Lac and PBSE-Syr-Lac modified cathodes demonstrated approximately 6 and 9 times increase in current density, respectively, compared to physically adsorbed and randomly oriented Lac cathodes. Further testing in solution utilizing BOx showed an even higher increase in achievable current densities, thus BOx was chosen for additional testing in air-breathing mode. In subsequent air-breathing experiments the incorporation of PBSE and Syr with BOx resulted in current densities of 0.65 ± 0.1 mA cm(-2); 2.5 times higher when compared to an unmodified BOx cathode. A fully tethered/oriented BOx cathode was combined with a NAD-dependent Glucose Dehydrogenase anode for the fabrication of a complete enzymatic membraneless fuel cell. A maximum power of 1.03 ± 0.06 mW cm(-2) was recorded for the complete fuel cell. The observed significant enhancement in the performance of "oriented" cathodes was a result of proper enzyme orientation, leading to facilitated enzyme/electrode interface interactions.

A Direct Grain-Boundary-Activity Correlation for CO Electroreduction on Cu Nanoparticles

PubMed Central

2016-01-01

Copper catalyzes the electrochemical reduction of CO to valuable C2+ products including ethanol, acetate, propanol, and ethylene. These reactions could be very useful for converting renewable energy into fuels and chemicals, but conventional Cu electrodes are energetically inefficient and have poor selectivity for CO vs H2O reduction. Efforts to design improved catalysts have been impeded by the lack of experimentally validated, quantitative structure–activity relationships. Here we show that CO reduction activity is directly correlated to the density of grain boundaries (GBs) in Cu nanoparticles (NPs). We prepared electrodes of Cu NPs on carbon nanotubes (Cu/CNT) with different average GB densities quantified by transmission electron microscopy. At potentials ranging from −0.3 V to −0.5 V vs the reversible hydrogen electrode, the specific activity for CO reduction to ethanol and acetate was linearly proportional to the fraction of NP surfaces comprised of GB surface terminations. Our results provide a design principle for CO reduction to ethanol and acetate on Cu. GB-rich Cu/CNT electrodes are the first NP catalysts with significant CO reduction activity at moderate overpotential, reaching a mass activity of up to ∼1.5 A per gram of Cu and a Faradaic efficiency >70% at −0.3 V. PMID:27163043

A Direct Grain-Boundary-Activity Correlation for CO Electroreduction on Cu Nanoparticles.

PubMed

Feng, Xiaofeng; Jiang, Kaili; Fan, Shoushan; Kanan, Matthew W

2016-03-23

Copper catalyzes the electrochemical reduction of CO to valuable C2+ products including ethanol, acetate, propanol, and ethylene. These reactions could be very useful for converting renewable energy into fuels and chemicals, but conventional Cu electrodes are energetically inefficient and have poor selectivity for CO vs H2O reduction. Efforts to design improved catalysts have been impeded by the lack of experimentally validated, quantitative structure-activity relationships. Here we show that CO reduction activity is directly correlated to the density of grain boundaries (GBs) in Cu nanoparticles (NPs). We prepared electrodes of Cu NPs on carbon nanotubes (Cu/CNT) with different average GB densities quantified by transmission electron microscopy. At potentials ranging from -0.3 V to -0.5 V vs the reversible hydrogen electrode, the specific activity for CO reduction to ethanol and acetate was linearly proportional to the fraction of NP surfaces comprised of GB surface terminations. Our results provide a design principle for CO reduction to ethanol and acetate on Cu. GB-rich Cu/CNT electrodes are the first NP catalysts with significant CO reduction activity at moderate overpotential, reaching a mass activity of up to ∼1.5 A per gram of Cu and a Faradaic efficiency >70% at -0.3 V.

An improved amperometric L-lactate biosensor based on covalent immobilization of microbial lactate oxidase onto carboxylated multiwalled carbon nanotubes/copper nanoparticles/polyaniline modified pencil graphite electrode.

PubMed

Dagar, Kusum; Pundir, C S

2017-01-01

An improved amperometric l-lactate biosensor was constructed based on covalent immobilization of lactate oxidase (LOx) from Pediococcus species onto carboxylated multiwalled carbon nanotubes (cMWCNT)/copper nanoparticles (CuNPs)/polyaniline (PANI) hybrid film electrodeposited on the surface of a pencil graphite electrode (PGE). The enzyme electrode was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS), while CuNPs synthesized by chemical reduction method, were characterized by transmission electron microscopy (TEM), UV spectrascopy and X-ray diffraction (XRD). The biosensor showed maximum response within 5s at pH 8.0 in 0.05M sodium phosphate buffer and 37°C, when operated at 20mVs -1 . The biosensor had a detection limit of 0.25μM with a wide working range between 1μM-2500μM. The biosensor was employed for measurement of l-lactic acid level in plasma of apparently healthy and diseased persons. Analytical recovery of added lactic acid in plasma was 95.5%. Within- and between-batch coefficients of variations were 6.24% and 4.19% respectively. There was a good correlation (R 2 =0.97) between plasma lactate values as measured by standard enzymatic spectrophotometric method and the present biosensor. The working enzyme electrode was used 180 times over a period of 140 days, when stored at 4°C. Copyright © 2016. Published by Elsevier Inc.

Catalytic aided electrical discharge machining of polycrystalline diamond - parameter analysis of finishing condition

NASA Astrophysics Data System (ADS)

Haikal Ahmad, M. A.; Zulafif Rahim, M.; Fauzi, M. F. Mohd; Abdullah, Aslam; Omar, Z.; Ding, Songlin; Ismail, A. E.; Rasidi Ibrahim, M.

2018-01-01

Polycrystalline diamond (PCD) is regarded as among the hardest material in the world. Electrical Discharge Machining (EDM) typically used to machine this material because of its non-contact process nature. This investigation was purposely done to compare the EDM performances of PCD when using normal electrode of copper (Cu) and newly proposed graphitization catalyst electrode of copper nickel (CuNi). Two level full factorial design of experiment with 4 center points technique was used to study the influence of main and interaction effects of the machining parameter namely; pulse-on, pulse-off, sparking current, and electrode materials (categorical factor). The paper shows interesting discovery in which the newly proposed electrode presented positive impact to the machining performance. With the same machining parameters of finishing, CuNi delivered more than 100% better in Ra and MRR than ordinary Cu electrode.

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)

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.

Electron transport in dipyridazine and dipyridimine molecular junctions: a first-principles investigation

NASA Astrophysics Data System (ADS)

Parashar, Sweta

2018-05-01

We present density functional theory-nonequilibrium Green’s function method for electron transport of dipyridazine and dipyridimine molecular junctions with gold, copper and nickel electrodes. Our investigation reveals that the junctions formed with gold and copper electrodes bridging dipyridazine molecule through thiol anchoring group enhance current as compared to the junctions in which the molecule and electrode were coupled directly. Further, nickel electrode displays weak decrease of current with increase of voltage at about 1.2 V. The result is fully rationalized by means of the distribution of molecular orbitals as well as shift in molecular energy levels and HOMO-LUMO gap with applied bias voltage. Our findings are compared with theoretical and experimental results available for other molecular junctions. Present results predict potential avenues for changing the transport behavior by not only changing the electrodes, but also the position of nitrogen atom and type of anchoring-atom that connect molecule and electrodes, thus extending applications of dipyridazine and dipyridimine molecule in future integrated circuits.

Spectroscopy peculiarities of thermal plasma of electric arc discharge between electrodes with Zn admixtures

NASA Astrophysics Data System (ADS)

Semenyshyn, R. V.; Veklich, A. N.; Babich, I. L.; Boretskij, V. F.

2014-10-01

Plasma of the free burning electric arc between Ag-SnO2-ZnO composite electrodes as well as brass electrodes were investigated. The plasma temperature distributions were obtained by Boltzmann plot method involving Cu I, Ag I or Zn I spectral line emissions. The electron density distributions were obtained from the width and from absolute intensity of spectral lines. The laser absorption spectroscopy was used for measurement of copper atom concentration in plasma. Plasma equilibrium composition was calculated using two independent groups of experimental values (temperature and copper atom concentration, temperature and electron density). It was found that plasma of the free burning electric arc between brass electrodes is in local thermodynamical equilibrium. The experimental verification of the spectroscopic data of Zn I spectral lines was carried out.

Purity test for copper-plating solutions

NASA Technical Reports Server (NTRS)

Mansfeld, F. B.

1977-01-01

Electrode configuration can be used to measure extent of impurities in acid-copper plating solution. It can be inserted into any plating tank and will show whether bath is clean or contaminated, within fifteen minutes.

An insight into the adsorption and electrochemical processes occurring during the analysis of copper and lead in wines, using an electrochemical quartz crystal nanobalance.

PubMed

Yamasaki, Alzira; Oliveira, João A B P; Duarte, Armando C; Gomes, M Teresa S R

2012-08-30

Copper and lead in wine were quantified by anodic stripping voltammetry (ASV), performed onto the gold electrode of a piezoelectric quartz crystal. Both current or mass changes could be used as analytical signals, without a statistical difference in the results (α=0.05). However, the plot of mass vs. potential provided an in depth understanding of the electrochemical processes and allowed studying adsorption phenomena. Copper interaction with fructose is an example of a process which was not possible to ignore by observing the mass change on the gold electrode of the piezoelectric quartz crystal. Copyright © 2012 Elsevier B.V. All rights reserved.

Fabrication and characterization of the organic rectifying junctions by electrolysis

NASA Astrophysics Data System (ADS)

Karimov, Khasan; Ahmad, Zubair; Ali, Rashid; Noor, Adnan; Akmal, M.; Najeeb, M. A.; Shakoor, R. A.

2017-08-01

Unlike the conventional solution processable deposition techniques, in this study, we propose a novel and economical method for the fabrication of organic rectifying junctions. The solutions of the orange dye, copper phthalocyanine and NaCl were deposited on the surface-type interdigitated silver electrodes using electrolysis technique. Using the current-voltage (I-V) characteristics, the presence of rectifying behavior in the samples has been confirmed. This phenomenon, in principle, can be used for fabrication of the diodes, transistors and memory devices.

Electrocatalytic Production of C3-C4 Compounds by Conversion of CO2 on a Chloride-Induced Bi-Phasic Cu2O-Cu Catalyst.

PubMed

Lee, Seunghwa; Kim, Dahee; Lee, Jaeyoung

2015-12-01

Electrocatalytic conversion of carbon dioxide (CO2) has recently received considerable attention as one of the most feasible CO2 utilization techniques. In particular, copper and copper-derived catalysts have exhibited the ability to produce a number of organic molecules from CO2. Herein, we report a chloride (Cl)-induced bi-phasic cuprous oxide (Cu2O) and metallic copper (Cu) electrode (Cu2OCl) as an efficient catalyst for the formation of high-carbon organic molecules by CO2 conversion, and identify the origin of electroselectivity toward the formation of high-carbon organic compounds. The Cu2OCl electrocatalyst results in the preferential formation of multi-carbon fuels, including n-propanol and n-butane C3-C4 compounds. We propose that the remarkable electrocatalytic conversion behavior is due to the favorable affinity between the reaction intermediates and the catalytic surface. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Copper oxide nanowires as better performance electrode material for supercapacitor application

NASA Astrophysics Data System (ADS)

Yar, A.; Dennis, J. O.; Mohamed, N. M.; Mian, M. U.; Irshad, M. I.; Mumtaz, A.

2016-11-01

Supercapacitors are highly attractive energy storage devices which are capable of delivering high power, with fast charging and long cycle life. Carbon based material rely on physical charging with less capacitance while metal oxide store charge by fast redox reaction with increased capacitance. Among metal oxide, copper oxide compounds are widely use in the form of nano and micro structures with no definite control over structure. In this work we utilized the well-controlled structure copper wires, originated from AAO template. Such well controlled structure offer better capacitance values due to easily excess of ions to the surface of wires. Performance of material was check in 3 M of potassium hydroxide (KOH). Specific capacitance (Cs) was calculated by using cyclic voltammetry (CV) and Charge discharge (CDC) test. The capacitance calculate on base on CV at 25 mV/s was 101.37 F/g while CDC showed the capacitance of 90 F/g at 2 A/g.

Ion beam treatment of potential space materials at the NASA Lewis Research Center

NASA Technical Reports Server (NTRS)

Kussmaul, Michael; Mirtich, Michael J.; Curren, Arthur

1992-01-01

Ion source systems in different configurations, have been used to generate unique morphologies for several NASA space applications. The discharge chamber of a 30 cm ion source was successfully used to texture potential space radiator materials for the purpose of obtaining values of thermal emittance greater than 0.85 at 700 and 900 K. High absorptance surfaces were obtained using ion beam seed texturing, for space radiator materials that were flown on the Long Duration Exposure Facility (LDEF) for 5.8 years in space. An ion source discharge chamber was also used to develop electrode surfaces with suppressed secondary electron emission characteristics for use in collectors in microwave amplifier traveling wave tubes. This was accomplished by sputtering textured carbon onto copper as well as texturing copper using tantalum and molybdenum as sacrificial texture inducing seeding materials. In a third configuration, a dual ion beam system was used to generate high transmittance diamondlike carbon (DLC) films.

Quantitative Determination of NTA and Other Chelating Agents in Detergents by Potentiometric Titration with Copper Ion Selective Electrode.

PubMed

Ito, Sana; Morita, Masaki

2016-01-01

Quantitative analysis of nitrilotriacetate (NTA) in detergents by titration with Cu 2+ solution using a copper ion selective electrode was achieved. This method tolerates a wide range of pH and ingredients in detergents. In addition to NTA, other chelating agents, having relatively lower stability constants toward Cu 2+ , were also qualified with sufficient accuracy by this analytical method for model detergent formulations. The titration process was automated by automatic titrating systems available commercially.

Critical Evaluation of State-of-the-Art In Situ Thermal Treatment Technologies for DNAPL Source Zone Treatment. State-of-the-Practice Overview

DTIC Science & Technology

2009-05-01

recovery in their design. Electrodes have been constructed from steel pipe , copper plate for heating distinct zones, and sheet pile. Sheet pile...energy transfer/ heating in the subsurface) The components required to implement ERH include: • Electrodes (steel pipe , copper plate, well points...including piping , blower, and condenser • A vapor treatment system Electrical Resistance Heating (Smith) A-3 • An ERH power control unit to

Hierarchically Flower-like N-Doped Porous Carbon Materials Derived from an Explosive 3-Fold Interpenetrating Diamondoid Copper Metal-Organic Framework for a Supercapacitor.

PubMed

Li, Zuo-Xi; Zou, Kang-Yu; Zhang, Xue; Han, Tong; Yang, Ying

2016-07-05

A peculiar copper metal-organic framework (Cu-MOF) was synthesized by a self-assembly method, which presents a 3-fold interpenetrating diamondoid net based on the square-planar Cu(II) node. Although it exhibits a high degree of interpenetration, the Cu-MOF still exhibits a one-dimensional channel, which provides a template for constructing porous materials through the "precursor" strategy. Furthermore, the explosive ClO4(-) ion, which resided in the channel, could induce the quick decomposition of organic ingredients and release a huge amount of gas, which is beneficial for the porosity of postsynthetic materials. Significantly, we first utilize this explosive MOF to prepare a series of Cu@C composites through the calcination-thermolysis method at different temperatures, which contain copper particles exhibiting various shapes and combinations with the carbon substrate. Considering the hole-forming effect of copper particles, Cu@C composites were etched by HCl to afford a sequence of hierarchically flower-like N-doped porous carbon materials (NPCs), which retain the original morphology of the Cu-MOF. Interestingly, NPC-900, originating from the calcination of the Cu-MOF at 900 °C, exhibits a more regular flower-like morphology, the largest specific surface area, abundant porosities, and multiple nitrogen functionalities. The remarkable specific capacitances are 138 F g(-1) at 5 mV s(-1) and 149 F g(-1) at 0.5 A g(-1) for the NPC-900 electrode in a 6 M potassium hydroxide aqueous solution. Moreover, the retention of capacitance remains 86.8% (125 F g(-1)) at 1 A g(-1) over 2000 cycles, which displays good chemical stability. These findings suggest that NPC-900 can be applied as a suitable electrode for a supercapacitor.

Roll-to-roll-compatible, flexible, transparent electrodes based on self-nanoembedded Cu nanowires using intense pulsed light irradiation

NASA Astrophysics Data System (ADS)

Zhong, Zhaoyang; Woo, Kyoohee; Kim, Inhyuk; Hwang, Hyewon; Kwon, Sin; Choi, Young-Man; Lee, Youngu; Lee, Taik-Min; Kim, Kwangyoung; Moon, Jooho

2016-04-01

Copper nanowire (Cu NW)-based flexible transparent conductive electrodes (FTCEs) have been investigated in detail for use in various applications such as flexible touch screens, organic photovoltaics and organic light-emitting diodes. In this study, hexadecylamine (HDA) adsorbed onto the surface of NWs is changed into polyvinylpyrrolidone (PVP) via a ligand exchange process; the high-molecular-weight PVP enables high dispersion stability. Intense pulsed light (IPL) irradiation is used to remove organic species present on the surface of the NWs and to form direct connections between the NWs rapidly without any atmospheric control. NWs are self-nanoembedded into a plastic substrate after IPL irradiation, which results in a smooth surface, strong NW/substrate adhesion, excellent mechanical flexibility and enhanced oxidation stability. Moreover, Cu NW FTCEs with high uniformities are successfully fabricated on a large area (150 mm × 200 mm) via successive IPL irradiation that is synchronized with the motion of the sample stage. This study demonstrates the possibility of roll-to-roll-based, large-scale production of low-cost, high-performance Cu NW-based FTCEs.Copper nanowire (Cu NW)-based flexible transparent conductive electrodes (FTCEs) have been investigated in detail for use in various applications such as flexible touch screens, organic photovoltaics and organic light-emitting diodes. In this study, hexadecylamine (HDA) adsorbed onto the surface of NWs is changed into polyvinylpyrrolidone (PVP) via a ligand exchange process; the high-molecular-weight PVP enables high dispersion stability. Intense pulsed light (IPL) irradiation is used to remove organic species present on the surface of the NWs and to form direct connections between the NWs rapidly without any atmospheric control. NWs are self-nanoembedded into a plastic substrate after IPL irradiation, which results in a smooth surface, strong NW/substrate adhesion, excellent mechanical flexibility and enhanced oxidation stability. Moreover, Cu NW FTCEs with high uniformities are successfully fabricated on a large area (150 mm × 200 mm) via successive IPL irradiation that is synchronized with the motion of the sample stage. This study demonstrates the possibility of roll-to-roll-based, large-scale production of low-cost, high-performance Cu NW-based FTCEs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00444j

Design and physical features of inductive coaxial copper vapor lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batenin, V. M.; Kazaryan, M. A.; Karpukhin, V. T.

A physical model of a copper vapor laser pumped by a pulse-periodic inductive (electrodeless) discharge is considered. The feasibility of efficient laser pumping by an inductive discharge and reaching high output parameters comparable to those of conventional copper vapor lasers pumped by a longitudinal electrode discharge is demonstrated. The design and physical features of an inductive copper vapor laser with an annular working volume are discussed.

Effect of Post Treatment For Cu-Cr Source/Drain Electrodes on a-IGZO TFTs.

PubMed

Hu, Shiben; Fang, Zhiqiang; Ning, Honglong; Tao, Ruiqiang; Liu, Xianzhe; Zeng, Yong; Yao, Rihui; Huang, Fuxiang; Li, Zhengcao; Xu, Miao; Wang, Lei; Lan, Linfeng; Peng, Junbiao

2016-07-27

We report a high-performance amorphous Indium-Gallium-Zinc-Oxide (a-IGZO) thin-film transistor (TFT) with new copper-chromium (Cu-Cr) alloy source/drain electrodes. The TFT shows a high mobility of 39.4 cm 2 ·V - 1 ·s - 1 a turn-on voltage of -0.8 V and a low subthreshold swing of 0.47 V/decade. Cu diffusion is suppressed because pre-annealing can protect a-IGZO from damage during the electrode sputtering and reduce the copper diffusion paths by making film denser. Due to the interaction of Cr with a-IGZO, the carrier concentration of a-IGZO, which is responsible for high mobility, rises.

Effect of Post Treatment For Cu-Cr Source/Drain Electrodes on a-IGZO TFTs

PubMed Central

Hu, Shiben; Fang, Zhiqiang; Ning, Honglong; Tao, Ruiqiang; Liu, Xianzhe; Zeng, Yong; Yao, Rihui; Huang, Fuxiang; Li, Zhengcao; Xu, Miao; Wang, Lei; Lan, Linfeng; Peng, Junbiao

2016-01-01

We report a high-performance amorphous Indium-Gallium-Zinc-Oxide (a-IGZO) thin-film transistor (TFT) with new copper-chromium (Cu-Cr) alloy source/drain electrodes. The TFT shows a high mobility of 39.4 cm2·V−1·s−1 a turn-on voltage of −0.8 V and a low subthreshold swing of 0.47 V/decade. Cu diffusion is suppressed because pre-annealing can protect a-IGZO from damage during the electrode sputtering and reduce the copper diffusion paths by making film denser. Due to the interaction of Cr with a-IGZO, the carrier concentration of a-IGZO, which is responsible for high mobility, rises. PMID:28773743

Indirect potentiometric titration of ascorbic acid in pharmaceutical preparations using copper based mercury film electrode.

PubMed

Abdul Kamal Nazer, Meeran Mohideen; Hameed, Abdul Rahman Shahul; Riyazuddin, Patel

2004-01-01

A simple and rapid potentiometric method for the estimation of ascorbic acid in pharmaceutical dosage forms has been developed. The method is based on treating ascorbic acid with iodine and titration of the iodide produced equivalent to ascorbic acid with silver nitrate using Copper Based Mercury Film Electrode (CBMFE) as an indicator electrode. Interference study was carried to check possible interference of usual excipients and other vitamins. The precision and accuracy of the method was assessed by the application of lack-of-fit test and other statistical methods. The results of the proposed method and British Pharmacopoeia method were compared using F and t-statistical tests of significance.

The effect of target materials on the propagation of atmospheric-pressure plasma jets

NASA Astrophysics Data System (ADS)

Ji, Longfei; Yan, Wen; Xia, Yang; Liu, Dongping

2018-05-01

The current study is focused on the effect of target materials (quartz plate, copper sheet, and quartz plate with a grounded copper sheet on the back) on the propagation of atmospheric-pressure helium plasma jets. The dynamics of ionization waves (IWs) and the relative amount of reactive oxygen species (OH and O) in the IW front were compared by using spatial and temporal images and relative optical emission spectroscopy. Our measurements show that the targets can significantly affect the propagation and intensity of the IWs. In addition, strong OH emission lines were detected when the IWs impinged upon the damp surface. Numerical simulations have been carried out to explain the experimental observation. The propagation velocity of IWs predicted by the simulation was in good agreement with the experimental results. Simulation results suggest that the density and velocity of IWs mainly depend on the electric field between the high voltage electrode tip and the target. Analysis indicates that the targets could change the electric field distribution between the high voltage electrode and targets and thus affect the dynamics and the density of the IWs, the generation of reactive oxygen species, and the corresponding sterilization efficiency.

Mass transfer study on the electrochemical removal of copper ions from synthetic effluents using reticulated vitreous carbon.

PubMed

Britto-Costa, Pedro H; Ruotolo, Luís Augusto M

2013-01-01

Porous electrodes have been successfully used for metal electrodeposition from diluted aqueous solution due to their high porosity and specific surface area, which lead to high mass transfer rates. This work studies the mass transfer of copper electrodeposition on reticulated vitreous carbon in a flow reactor without membrane. The flow configuration, otherwise the filter-press electrochemical reactors, was designed in order to minimize the pressure drop. The mass transfer coefficient was determined by voltammetric and galvanostatic electrodeposition. In the voltammetric experiments a Luggin capillary was used to measure the current-potential curves and to determine the limiting current (and, consequently, the mass transfer coefficient). In the galvanostatic experiments the concentration-time curves were obtained and considering a limiting current kinetics model, the mass transfer coefficient (k(m)) was determined for different flow velocities. The results showed that both methods give similar values of k(m), thus the voltammetric method can be recommended because it is faster and simpler. Finally, the reactor performance was compared with others from literature, and it was observed that the proposed reactor design has high Sherwood numbers similar to other reactor configurations using membranes and reticulated vitreous carbon electrodes.

Sub-micrometer particles produced by a low-powered AC electric arc in liquids.

PubMed

Jaworski, Jacek A; Fleury, Eric

2012-01-01

The article presents the report of the production of composites of sub-micrometer metal particles in matrix consisted of the metal compounds by means of an AC electric arc in water and paraffin solutions using electrodes carbon-metal and metal-metal (metal: Ni, Fe, Co, Cu). The advantage of this method is the low electric power (from 5 to 10 W) needed in comparison to standard DC arc-discharge methods (0.8 to 3 kW). This method enables the production of particles from conductive material also in wide range of temperature and in solvent which could be either transparent to light or opaque. Moreover the solvent can be electrolyte or insulating liquid. The microstructure of the composite layer was investigated by scanning electron microscopy (SEM), Electron Probe Microanalysis (EPMA) and X-ray. During particles production in water metal oxides were created. Additionally using cobalt-copper, nickel-copper as couple electrodes, insoluble in water copper (II) hydroxide crystal grains were created additionally which crystals shape was depended on transition metal. For iron-copper couple electrodes system the copper (II) hydroxide was not formed. Experiments with sequence production of Ni and Fe particles with C electrode assisting in molten paraffin let to obtain both Ni and Fe particles surrounded by paraffin. After solidification the material was insulator but if locally magnetic field influenced on the liquid solution in that place after solidification a new composite was created which was electric current conductor with resistivity around 0.1 omega x m, was attracted by magnetic field and presented magneto resistance around 0.4% in changing magnetic field in a range 150 mT. After mixing the concentrated paraffin with normal paraffin resistivity of the mixture increased and it became photosensitive and created small voltage under light influence.

Fiber optic apparatus for detecting molecular species by surface enhanced Raman spectroscopy

DOEpatents

Angel, Stanley M.; Sharma, Shiv K.

1988-01-01

Optrode apparatus for detecting constituents of a fluid medium includes an optical fiber (13, 13a to 13e) having a metal coating (22, 22a to 22e) on at least a portion of a light transmissive core (17, 17a to 17d). The metal is one, such as silver, gold or copper, which enhances emission of Raman signal frequencies by molecules adsorbed on the surface of the coating when monochromatic probe light of a different frequency is scattered by such molecules and the metal coating is sufficiently thin to transmit light between the absorbed molecules and the core of the fiber. Probe light is directed into one end of the fiber and a detector (16, 16d, 16e) analyzes light emitted from the fiber for Raman frequencies that identify one or more particular molecular species. In one form, the optrode (13e) may function as a working electrode of an electrochemical cell (53) while also serving to detect the products of oxidation or reduction reactions which occur at the electrode surface.

Influencing the arc and the mechanical properties of the weld metal in GMA-welding processes by additive elements on the wire electrode surface

NASA Astrophysics Data System (ADS)

Wesling, V.; Schram, A.; Müller, T.; Treutler, K.

2016-03-01

Under the premise of an increasing scarcity of raw materials and increasing demands on construction materials, the mechanical properties of steels and its joints are gaining highly important. In particular high- and highest-strength steels are getting in the focus of the research and the manufacturing industry. To the same extent, the requirements for filler metals are increasing as well. At present, these low-alloy materials are protected by a copper coating (<1μm) against corrosion. In addition, the coating realizes a good ohmic contact and good sliding properties between the welding machine and the wire during the welding process. By exchanging the copper with other elements it should be possible to change the mechanical properties of the weld metal and the arc stability during gas metal arc welding processes and keep the basic functions of the coating nearly untouched. On a laboratory scale solid wire electrodes with coatings of various elements and compounds such as titanium oxide were made and processed with a Gas Metal Arc Welding process. During the processing a different process behavior between the wire electrodes, coated and original, could be observed. The influences ranges from greater/shorter arc-length over increasing/decreasing droplets to larger/smaller arc foot point. Furthermore, the weld metal of the coated electrodes has significantly different mechanical and technological characteristics as the weld metal from the copper coated ground wire. The yield strength and tensile strength can be increased by up to 50%. In addition, the chemical composition of the weld metal was influenced by the application of coatings with layer thicknesses to 15 microns in the lower percentage range (up to about 3%). Another effect of the coating is a modified penetration. The normally occurring “argon finger” can be suppressed or enhanced by the choice of the coating. With the help of the presented studies it will be shown that Gas Metal Arc Welding processes are significantly affected by thin film coatings on solid wire electrodes for Gas Metal Arc welding. The influences are regarding the stability of the arc, the properties of the weld metal in terms of geometric expression, chemical composition and mechanical properties, the composition of the arc-plasma and the dynamics of the molten metal.

Graphene-based copper oxide thin film nanostructures as high-efficiency photocathode for p-type dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Kilic, Bayram; Turkdogan, Sunay; Astam, Aykut; Baran, Sümeyra Seniha; Asgin, Mansur; Cebeci, Hulya; Urk, Deniz

2017-10-01

Graphene-based p-type dye-sensitized solar cells (p-DSSCs) have been proposed and fabricated using copper oxide urchin-like nanostructures (COUN) as photocathode with an FeS2 counter electrode (CE). COUN composed of Cu2O core sphere and CuO shell nanorods with overall diameters of 2 to 4 μm were grown by a simple hydrothermal method with self-assemble nucleation. It was figured out that the formation of copper oxide core/shell structures could be adjusted by an ammonia additive leading to pH change of the precursor solution. In addition to a photocathode, we also demonstrated FeS2 thin films as an efficient CE material alternative to the conventional Pt CEs in DSSCs. FeS2 nanostructures, with diameters of 50 to 80 nm, were synthesized by a similar hydrothermal approach. FeS2 nanostructures are demonstrated to be an outstanding CE material in p-DSSCs. We report graphene/COUN as photocathode and Pt/FeS2 as CE in p-DSSCs, and results show that the synergetic combination of electrodes in each side (increased interconnectivity between COUN and graphene layer, high surface area, and high catalytic activity of FeS2) increased the power conversion efficiency from 1.56% to 3.14%. The excellent performances of COUN and FeS2 thin film in working and CEs, respectively, make them unique choices among the various photocathode and CE materials studied.

Corrosive effect of the type of soil in the systems of grounding more used (copper and stainless steel) for local soil samples from the city of Tunja (Colombia), by means of electrochemical techniques

NASA Astrophysics Data System (ADS)

Guerrero, L.; Salas, Y.; Blanco, J.

2016-02-01

In this work electrochemical techniques were used to determine the corrosion behaviour of copper and stainless steel electrodes, used in grounding varying soil type with which they react. A slight but significant change in the corrosion rate, linear polarization resistance and equivalent parameters in the technique of electrochemical impedance spectroscopy circuit was observed. Electrolytes in soils are slightly different depending on laboratory study, but the influence was noted in the retention capacity of water, mainly due to clays, affecting ion mobility and therefore measures such as the corrosion rate. Behaviour was noted in lower potential for copper corrosion, though the corrosion rate regardless of the type of soil, was much higher for electrodes based on copper, by several orders of magnitude.

Electrode for molten carbonate fuel cell

DOEpatents

Iacovangelo, Charles D.; Zarnoch, Kenneth P.

1983-01-01

A sintered porous electrode useful for a molten carbonate fuel cell is produced which is composed of a plurality of 5 wt. % to 95 wt. % nickel balance copper alloy encapsulated ceramic particles sintered together by the alloy.

Electrolytic cell-free 57Co deposition for emission Mössbauer spectroscopy

NASA Astrophysics Data System (ADS)

Zyabkin, Dmitry V.; Procházka, Vít; Miglierini, Marcel; Mašláň, Miroslav

2018-05-01

We have developed a simple, inexpensive and efficient method for an electrochemical preparation of samples for emission Mössbauer spectroscopy (EMS) and Mössbauer sources. The proposed electrolytic deposition procedure does not require any special setup, not even an electrolytic cell. It utilizes solely an electrode with a droplet of electrolyte on its surface and the second electrode sunk into the droplet. Its performance is demonstrated using two examples, a metallic glass and a Cu stripe. We present a detailed description of the deposition procedure and resulting emission Mössbauer spectra for both samples. In the case of a Cu stripe, we have performed EMS measurements at different stages of heat-treatment, which are required for the production of Mössbauer sources with the copper matrix.

Active Piezoelectric Diaphragms

NASA Technical Reports Server (NTRS)

Bryant, Robert G.; Effinger, Robert T., IV; Aranda, Isaiah, Jr.; Copeland, Ben M.; Covington, Ed W., III

2002-01-01

Several active piezoelectric diaphragms were fabricated by placing unelectroded piezoelectric disks between copper clad films patterned with Inter-Circulating Electrodes "ICE". When a voltage potential is applied to the electrodes, the result is radially distributed electric field that mechanically strains the piezo-ceramic along the Z-axis (perpendicular to the applied electric field), rather than the expected in-plane (XY-axis) direction. Unlike other out of plane piezoelectric actuators, which are benders, these Radial Field Diaphragms (RFDs) strain concentrically yet afford high displacements while maintaining a constant circumference. This paper covers the fabrication and characterization of these diaphragms as a function of poling field strength, ceramic diameter and line spacing, as well as the surface topography, the resulting strain field and displacement as a function of applied voltage ranging from DC to 10 Hz.

Fabrication and applications of copper sulfide (CuS) nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shamraiz, Umair, E-mail: umairshamraiz@gmail.com; Hussain, Raja Azadar, E-mail: hussainazadar@gamil.com; Badshah, Amin, E-mail: aminbadshah@yahoo.com

2016-06-15

This review article presents different fabrication procedures (under the headlines of solvothermal routes, aerosol methods, solution methods and thermolysis), and applications (photocatalytic degradation, ablation of cancer cells, electrode material in lithium ion batteries and in gas sensing, organic solar cells, field emission properties, super capacitor applications, photoelectrochemical performance of QDSCs, photocatalytic reduction of organic pollutants, electrochemical bio sensing, enhanced PEC characteristics of pre-annealed CuS film electrodes) of copper sulfide (Covellite). - Highlights: • This review article presents the synthesis and applications of copper sulfide. • CuS has been used over the years for different applications in nanoscience. • Different syntheticmore » protocols are followed for their preparation which help in the possible modifications in the morphology of CuS.« less

Construction of leaf-like CuO-Cu2O nanocomposites on copper foam for high-performance supercapacitors.

PubMed

He, Dong; Wang, Guanda; Liu, Guolong; Suo, Hui; Zhao, Chun

2017-03-07

Leaf-like CuO-Cu 2 O nanosheets have been prepared on copper foam by a one-step simple anodization method, which can be used as an advanced binder-free supercapacitor electrode. The performance of the CuO-Cu 2 O/Cu foam electrode was optimized through controlling and restraining the current density and reaction time. The prepared electrode exhibits a very high specific capacitance (1.954 F cm -2 at a scan rate of 2 mV s -1 ), excellent durability (120% retention after 5000 cycles), remarkable rate capability (91.8% retention upon increasing the current density by 10 times) and good coulombic efficiency (78.2% at a current density of 2 mA cm -2 ). The facile and cost-effective fabrication process is also suitable for large scale practical production. These results indicate the leaf-like CuO-Cu 2 O/Cu foam electrode would be a promising electrode for high-performance supercapacitor applications.

Transition Metal Polypyridine Complexes: Studies of Mediation in Dye-Sensitized Solar Cells and Charge Separation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elliott, C. Michael; Prieto, Amy L.

2017-02-08

The Elliott group has long been supported by DOE for studies of cobalt(II/III) trisbypiridine (DTB) mediator complexes in dye sensitized solar cells. Previous work demonstrated that Co(II/III) chemistry is sensitive to the environment, showing unprecedented electrode-surface and electrolyte dependant voltammetry. In electrolytes that have large lipophilic cations, voltammetry of the [Co(DTB) 3] 2+/3+ couple is nearly Nernstian in appearance on nominally oxide-free metal surfaces. In contrast, on semiconductor electrodes in electrolytes with small, hard cations such as Li +, the electron transfer rates are so slow that it is difficult to measure any Faradaic current even at overpotentials of ±1more » V. These studies are of direct relevance to the operation of cobalt-based mediators in solar cells. The research has also shown that these mediators are compatible with copper phenantroline based dyes, in contrast to I - due to the insolubility of CuI.« less

Effect of copper concentration in the electrolyte on the surface morphology and the microstructure of CuInSe2 films

NASA Astrophysics Data System (ADS)

Hung, Pin-Kun; Kuo, Ting-Wei; Huang, Kuo-Chan; Wang, Na-Fu; Hsieh, Po-Tsung; Houng, Mau-Phon

2012-07-01

The surface morphology and the microstructure of CuInSe2 precursor films have been investigated by co-electrodeposition with different [Cu2+] concentrations from 2 mM to 4 mM. The characteristic of the precursor films was examined using field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), glancing incidence angle X-ray diffraction (GIXRD) and micro-Raman spectrometer, respectively. The surface morphology of the precursor films become more smoother and compact with choice of appropriate [Cu2+] concentration (3-3.5 mM) in the electrolyte. The relation between surface morphology and [Cu2+] concentration is also considered in terms of electrodeposition nucleation mechanisms using the mathematical models of Scharifker and Hills. It is suggested that the higher [Cu2+] concentrations can provide more numbers of nucleation sites on the surface of the electrode. Results simulated from the Rietveld refinement method suggest that decreasing dCusbnd Se is related to charge transfer from interstitial copper atoms and can affect the film microstructure. Micro-Raman spectrum also shows that the excess Cu atoms in the precursor films does not contribute significantly to large amounts of secondary phases but rather exists in the crystallite structure as other defect types.

An ultrasensitive electrochemiluminescence sensor based on reduced graphene oxide-copper sulfide composite coupled with capillary electrophoresis for determination of amlodipine besylate in mice plasma.

PubMed

Wei, Yanfen; Wang, Hao; Sun, Shuangjiao; Tang, Lifu; Cao, Yupin; Deng, Biyang

2016-12-15

A new electrochemiluminescence (ECL) sensor based on reduced graphene oxide-copper sulfide (rGO-CuS) composite coupled with capillary electrophoresis (CE) was constructed for the ultrasensitive detection of amlodipine besylate (AML) for the first time. In this work, rGO-CuS composite was synthesized by one-pot hydrothermal method and used for electrode modification. The electrochemical and ECL behaviors of the sensor were investigated. More than 5-fold enhance in ECL intensity was observed after modified with rGO-CuS composite. The results can be ascribed to the presence of rGO-CuS composite on the electrode surface that facilitates the electron transfer rate between the electroactive center of Ru(bpy)3(2+) and the electrode. The ECL sensor was coupled with CE to improve the selectivity and the CE-ECL parameters that affect separation and detection were optimized. Under the optimum conditions, the linear ranges for AML was 0.008-5.0μg/mL with a detection limit of 2.8ng/mL (S/N=3). The method displayed the advantages of high sensitivity, good selectivity, wide linear range, low detection limit and fine reproducibility, and was used to analyze AML in mice plasma with a satisfactory result, which holds a great potential in the field of pharmaceutical analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

Design and development of high efficiency 140W space TWT with graphite collector

NASA Astrophysics Data System (ADS)

Srivastava, V.; Purohit, G.; Sharma, R. K.; Sharma, S. M.; Bera, A.; Bhaskar, P. V.; Singh, R. R.; Prasad, K.; Kiran, V.

2008-05-01

4-stage graphite collector assembly has been designed and developed for a 140W Ku-band space TWT to achieve the collector efficiency more than 80%. The UHV compatible, high density, copper impregnated POCO graphite (DFP-1C) was used to fabricate the four collector electrodes of the 4-stage depressed collector. Copper impregnated graphite material is used for the collector electrodes because of its low secondary electron emission coefficient, high thermal and electrical conductivities, easy machining and brazing, low thermal expansion coefficient and low weight. The graphite material was characterized for the UHV compatibility. The collector electrodes were precisely fabricated by careful machining, and technology was developed for brazing of graphite electrodes with high voltage alumina insulators. Complete TWT with four-stage graphite collector was developed and 140W output power at gain more than 55 dB was achieved. The TWT was pumped from both the gun and the collector ends.

Self-sustained focusing of high-density streaming plasma

NASA Astrophysics Data System (ADS)

Bugaev, A.; Dobrovolskiy, A.; Goncharov, A.; Gushenets, V.; Litovko, I.; Naiko, I.; Oks, E.

2017-01-01

We describe our observations of the transport through an electrostatic plasma lens of a wide-aperture, high-current, low energy, metal-ion plasma flow produced by a cathodic arc discharge. The lens input aperture was 80 mm, the length of the lens was 140 mm, and there were three electrostatic ring electrodes located in a magnetic field formed by permanent magnets. The lens outer electrodes were grounded and the central electrode was biased up to -3 kV. The plasma was a copper plasma with directed (streaming) ion energy 20-40 eV, and the equivalent ion current was up to several amperes depending on the potential applied to the central lens electrode. We find that when the central lens electrode is electrically floating, the current density of the plasma flow at the lens focus increases by up to 40%-50%, a result that is in good agreement with a theoretical treatment based on plasma-optical principles of magnetic insulation of electrons and equipotentialization along magnetic field lines. When the central lens electrode is biased negatively, an on-axis stream of energetic electrons is formed, which can also provide a mechanism for focusing of the plasma flow. Optical emission spectra under these conditions show an increase in intensity of lines corresponding to both copper atoms and singly charged copper ions, indicating the presence of fast electrons within the lens volume. These energetic electrons, as well as accumulating on-axis and providing ion focusing, can also assist in reducing the microdroplet component in the dense, low-temperature, metal plasma.

Influence of electrical resistivity and machining parameters on electrical discharge machining performance of engineering ceramics.

PubMed

Ji, Renjie; Liu, Yonghong; Diao, Ruiqiang; Xu, Chenchen; Li, Xiaopeng; Cai, Baoping; Zhang, Yanzhen

2014-01-01

Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge machining ZnO/Al2O3 ceramic.

Recycling Metals from Spent Screen-Printed Electrodes While Learning the Fundamentals of Electrochemical Sensing

ERIC Educational Resources Information Center

González-Sánchez, María-Isabel; Gómez-Monedero, Beatriz; Agrisuelas, Jerónimo; Valero, Edelmira

2018-01-01

A laboratory experiment in which students recycle silver and platinum selectively from spent screen-printed platinum electrodes is described. The recovered silver in solution is used to show its spontaneous redox reaction with a copper sheet. The recovered platinum is electrodeposited onto a screen-printed carbon electrode to develop a sensor for…

Corrosion behaviour of high copper dental amalgams.

PubMed

Yap, A U J; Ng, B L; Blackwood, D J

2004-06-01

This study evaluated the corrosion behaviour of two high copper dental amalgam alloys [Dispersalloy (Dentsply-Caulk) and Tytin (Kerr)] in different electrolytes. Amalgam specimens were prepared, coupled to a copper wire, cemented into glass tubes and polished to a 600-grit finish. A corrosion cell was prepared using a carbon counter-electrode, a standard calomel electrode as the reference and amalgam as the working electrode. The alloys were tested in the following mediums at 37 degrees C: (i) artificial saliva based on Fusayama's solution (FS), (ii) artificial saliva with citric acid adjusted to pH 4.0 (FC) and (iii) 1% sodium chloride solution (SC). Corrosion potentials (E(corr)) and corrosion rates (I(corr)) were determined using potentiostatic and impedance spectroscopy methods. Data was subjected to anova/Scheffe's post hoc test at 0.05 significance level. For both alloys, the corrosion potential in FS was significantly greater than in SC. Corrosion potential of Tytin in FS and SC was also significantly greater than in FC. The corrosion rate of Dispersalloy in FC was significantly greater than in FS and SC. For Tytin, corrosion rate in SC was significantly greater than in FS and FC. Although no significant difference in corrosion potential/rate was observed between the alloys when tested in FS, significant differences were observed when electrochemical testing was carried out in FC and SC. The corrosion behaviour of high copper amalgam alloys are both material and environment dependent. Certain food substances may increase the corrosion of high copper amalgams.

Copper atomic-scale transistors.

PubMed

Xie, Fangqing; Kavalenka, Maryna N; Röger, Moritz; Albrecht, Daniel; Hölscher, Hendrik; Leuthold, Jürgen; Schimmel, Thomas

2017-01-01

We investigated copper as a working material for metallic atomic-scale transistors and confirmed that copper atomic-scale transistors can be fabricated and operated electrochemically in a copper electrolyte (CuSO 4 + H 2 SO 4 ) in bi-distilled water under ambient conditions with three microelectrodes (source, drain and gate). The electrochemical switching-on potential of the atomic-scale transistor is below 350 mV, and the switching-off potential is between 0 and -170 mV. The switching-on current is above 1 μA, which is compatible with semiconductor transistor devices. Both sign and amplitude of the voltage applied across the source and drain electrodes ( U bias ) influence the switching rate of the transistor and the copper deposition on the electrodes, and correspondingly shift the electrochemical operation potential. The copper atomic-scale transistors can be switched using a function generator without a computer-controlled feedback switching mechanism. The copper atomic-scale transistors, with only one or two atoms at the narrowest constriction, were realized to switch between 0 and 1 G 0 ( G 0 = 2e 2 /h; with e being the electron charge, and h being Planck's constant) or 2 G 0 by the function generator. The switching rate can reach up to 10 Hz. The copper atomic-scale transistor demonstrates volatile/non-volatile dual functionalities. Such an optimal merging of the logic with memory may open a perspective for processor-in-memory and logic-in-memory architectures, using copper as an alternative working material besides silver for fully metallic atomic-scale transistors.

High stored-energy breakdown tests on electrodes made of stainless steel, copper, titanium and molybdenum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esch, H. P. L. de, E-mail: hubert.de-esch@cea.fr; Simonin, A.; Grand, C.

2015-04-08

IRFM have conducted resilience tests on electrodes made of Cu, stainless steel 304L, Ti and Mo against breakdowns up to 170 kV and 300 J. The tests of the 10×10 cm{sup 2} electrodes have been performed at an electrode distance d=11 mm under vacuum (P∼5×10{sup −6} mbar). No great difference in voltage holding between the materials could be identified; all materials could reach a voltage holding between 140 and 170 kV over the 11 mm gap, i.e. results scatter within a ±10% band. After exposure to ∼10000 seconds of high-voltage (HV) on-time, having accumulated ∼1000 breakdowns, the electrodes were inspected. The anodes were covered with largemore » and small craters. The rugosity of the anodes had increased substantially, that of the cathodes to a lesser extent. The molybdenum electrodes are least affected, but this does not show in their voltage holding capability. It is hypothesized that penetrating high-energy electrons from the breakdown project heat below the surface of the anode and cause a micro-explosion of material when melting point is exceeded. Polished electrodes have also been tested. The polishing results in a substantially reduced breakdown rate in the beginning, but after having suffered a relatively small number (∼100) of breakdowns, the polished electrodes behaved the same as the unpolished ones.« less

COPPER COMPLEXATION BY NATURAL ORGANIC MATTER IN CONTAMINATED AND UNCOMTAINATED GROUND WATER

EPA Science Inventory

Ground-water samples were collected from an uncontaminated and a contaminated site. Copper complexation was characterized by ion-selective electrode (ISE), fluorescence quenching (FQ), and cathodic stripping voltammetric (CSV) titrations. All of the samples were titrated at their...

Multilayer core-shell structured composite paper electrode consisting of copper, cuprous oxide and graphite assembled on cellulose fibers for asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Wan, Caichao; Jiao, Yue; Li, Jian

2017-09-01

An easily-operated and inexpensive strategy (pencil-drawing-electrodeposition-electro-oxidation) is proposed to synthesize a novel class of multilayer core-shell structured composite paper electrode, which consists of copper, cuprous oxide and graphite assembled on cellulose fibers. This interesting electrode structure plays a pivotal role in providing more active sites for electrochemical reactions, facilitating ion and electron transport and shorting their diffusion pathways. This electrode demonstrates excellent electrochemical properties with a high specific capacitance of 601 F g-1 at 2 A g-1 and retains 83% of this capacitance when operated at an ultrahigh current density of 100 A g-1. In addition, a high energy density of 13.4 W h kg-1 at the power density of 0.40 kW kg-1 and a favorable cycling stability (95.3%, 8000 cycles) were achieved for this electrode. When this electrode was assembled into an asymmetric supercapacitor with carbon paper as negative electrode, the device displays remarkable electrochemical performances with a large areal capacitances (122 mF cm-2 at 1 mA cm-2), high areal energy density (10.8 μW h cm-2 at 402.5 μW cm-2) and outstanding cycling stability (91.5%, 5000 cycles). These results unveil the potential of this composite electrode as a high-performance electrode material for supercapacitors.

The Role of Subsurface Oxygen on Cu Surfaces for CO 2 Electrochemical Reduction

DOE PAGES

Fields, Meredith; Hong, Xin; Norskov, Jens K.; ...

2018-06-12

Under ambient conditions, copper with oxygen near the surface displays strengthened CO 2 and CO adsorption energies. This finding is often used to rationalize differences seen in product distributions between Cu-oxide and pure Cu electrodes during electrochemical CO 2 reduction. However, little evidence exists to confirm the presence of oxygen within first few layers of the Cu matrix under relevant experimental reducing conditions. As a result, using density functional theory calculations, we discuss the stability of subsurface oxygen from thermodynamic and kinetic perspectives, and show that under reducing potentials, subsurface oxygen alone should have negligible effects on the activity ofmore » crystalline Cu.« less

The Role of Subsurface Oxygen on Cu Surfaces for CO 2 Electrochemical Reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fields, Meredith; Hong, Xin; Norskov, Jens K.

Under ambient conditions, copper with oxygen near the surface displays strengthened CO 2 and CO adsorption energies. This finding is often used to rationalize differences seen in product distributions between Cu-oxide and pure Cu electrodes during electrochemical CO 2 reduction. However, little evidence exists to confirm the presence of oxygen within first few layers of the Cu matrix under relevant experimental reducing conditions. As a result, using density functional theory calculations, we discuss the stability of subsurface oxygen from thermodynamic and kinetic perspectives, and show that under reducing potentials, subsurface oxygen alone should have negligible effects on the activity ofmore » crystalline Cu.« less

Energy Harvesting from Salinity Gradient

NASA Astrophysics Data System (ADS)

Muhthassim, B.; Thian, X. K.; Hasan, K. N. Md

2018-04-01

Abstract: Energy harvesting from salt water received attention started back in 1970s’, but due to varying interests in the field and the growing potentials of other more promising sources, more work was required to fully establish it. This paper aims at identifying existing techniques of energy harvesting and the methodology involved determining an effective technique for small scale applications of the method. Capacitive deionization technique which involves electrochemical reaction was chosen for further analysis. The experiment was conducted to analyze factors affecting its performance including the electrode and the electrolyte. Combination electrode of carbon/aluminium, copper/aluminium and carbon/copper were selected and tested with different concentration of salty water. From the experiment, copper and aluminum electrodes were found to be the most effective among the rest. A DC-DC boost converter was used to step-up the voltage. Physical implementation of the circuit was done and the circuit was tested in which an input voltage of 1.022 V was boosted to 1.255 V. The efficiency of the boost converter was 38.17 % based on input power and output power obtained.

Formation of ultralong copper nanowires by hydrothermal growth for transparent conducting applications

NASA Astrophysics Data System (ADS)

Balela, Mary Donnabelle L.; Tan, Michael

2017-07-01

Transparent conducting electrodes are key components of optoelectronic devices, such as touch screens, organic light emitting diodes (OLEDs) and solar cells. Recent market surveys have shown that the demands for these devices are rapidly growing at a tremendous rate. Semiconducting oxides, in particular indium tin oxide (ITO) are the material of choice for transparent conducting electrodes. However, these conventional oxides are typically brittle, which limits their applicability in flexible electronics. Metal nanowires, e.g. copper (Cu) nanowires, are considered as the best candidate as substitute for ITO due to their excellent mechanical and electrical properties. In this paper, ultralong copper (Cu) nanowires with were successfully prepared by hydrothermal growth at 50-80°C for 1 h. Ethylenediamine was employed as the structure-directing agents, while hydrazine was used as the reductant. In situ mixed potential measurement was also carried out to monitor Cu deposition. Higher temperature shifted the mixed potential negatively, leading to thicker Cu nanowires. Transparent conducting electrode, with a sheet resistance of 197 Ω sq-1 at an optical transmittance of around 61 %, was fabricated with the Cu nanowire ink.

Cermet anode with continuously dispersed alloy phase and process for making

DOEpatents

Marschman, Steven C.; Davis, Norman C.

1989-01-01

Cermet electrode compositions and methods for making are disclosed which comprise NiO--NiFe.sub.2 O.sub.4 --Cu--Ni. Addition of an effective amount of a metallic catalyst/reactant to a composition of a nickel/iron/oxide, NiO, copper, and nickel produces a stable electrode having significantly increased electrical conductivity. The metallic catalyst functions to disperse the copper and nickel as an alloy continuously throughout the oxide phase of the cermet to render the electrode compositon more highly electrically conductive than were the third metal not present in the base composition. The third metal is preferably added to the base composition as elemental metal and includes aluminum, magnesium, sodium and gallium. The elemental metal is converted to a metal oxide during the sintering process.

Application of polymer-coated glassy carbon electrodes to the direct determination of trace metals in body fluids by anodic tripping voltametry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoyer, B.; Florence, T.M.

This paper describes the use of a polymer-coated thin mercury film electrode for the direct determination of trace metals in body fluids by anodic stripping voltametry. The antifouling properties of the membrane coating greatly improve the analytical signal in comparison with the conventional thin mercury film electrode. Lead in whole blood, urine, and sweat and copper in sweat can be determined accurately with sample acidification as the only pretreatment step, while the determination of copper in serum requires sample deproteination prior to analysis. Owing to an improved procedure for the preparation of the perfluorosulfonated membrane, the lifetime of the electrodemore » is at least one working day when used continuously in acidified body fluids.« less

Simulation and Measurement of Through-the-Earth, Extremely Low-Frequency Signals Using Copper-Clad Steel Ground Rods.

PubMed

Damiano, Nicholas William; Yan, Lincan; Whisner, Bruce; Zhou, Chenming

2017-01-01

The underground mining environment can greatly affect radio signal propagation. Understanding how the earth affects signal propagation is a key to evaluating communications systems used during a mine emergency. One type of communication system is through-the-earth, which can utilize extremely low frequencies (ELF). This paper presents the simulation and measurement results of recent National Institute for Occupational Safety and Health (NIOSH) research aimed at investigating current injection at ELF, and in particular, ground contact impedance. Measurements were taken at an outside surface testing location. The results obtained from modeling and measurement are characterized by electrode impedance, and the voltage received between two distant electrodes. This paper concludes with a discussion of design considerations found to affect low-frequency communication systems utilizing ground rods to inject a current into the earth.

Simulation and Measurement of Through-the-Earth, Extremely Low-Frequency Signals Using Copper-Clad Steel Ground Rods

PubMed Central

Damiano, Nicholas William; Yan, Lincan; Whisner, Bruce; Zhou, Chenming

2017-01-01

The underground mining environment can greatly affect radio signal propagation. Understanding how the earth affects signal propagation is a key to evaluating communications systems used during a mine emergency. One type of communication system is through-the-earth, which can utilize extremely low frequencies (ELF). This paper presents the simulation and measurement results of recent National Institute for Occupational Safety and Health (NIOSH) research aimed at investigating current injection at ELF, and in particular, ground contact impedance. Measurements were taken at an outside surface testing location. The results obtained from modeling and measurement are characterized by electrode impedance, and the voltage received between two distant electrodes. This paper concludes with a discussion of design considerations found to affect low-frequency communication systems utilizing ground rods to inject a current into the earth. PMID:29176916

CuC1 thermochemical cycle for hydrogen production

DOEpatents

Fan, Qinbai [Chicago, IL; Liu, Renxuan [Chicago, IL

2012-01-03

An electrochemical cell for producing copper having a dense graphite anode electrode and a dense graphite cathode electrode disposed in a CuCl solution. An anion exchange membrane made of poly(ethylene vinyl alcohol) and polyethylenimine cross-linked with a cross-linking agent selected from the group consisting of acetone, formaldehyde, glyoxal, glutaraldehyde, and mixtures thereof is disposed between the two electrodes.

Electrical contacting of an assembly of pseudoazurin and nitrite reductase using DNA-directed immobilization.

PubMed

Tepper, Armand W J W

2010-05-12

A method for the electrical contacting of redox enzymes that obtain oxidizing or reducing equivalents from small electron-transfer proteins is demonstrated. The electrochemical contacting of redox enzymes through their immobilization onto electrode supports offers great potential for technological applications and for fundamental studies, but finding appropriate methods to immobilize the enzymes in an orientation allowing rapid electron transfer with the electrode has proven difficult. The copper enzyme nitrite reductase (NiR) and its natural electron-exchange partner pseudoazurin (Paz) are conjugated to a specific DNA tag and immobilized to a gold electrode into a stoichiometrically defined assembly. The DNA tethered to the electrode surface acts as flexible place-holder for the protein components, allowing both proteins to move within the construct. It is shown that Paz efficiently shuttles electrons between the electrode and the NiR enzyme, allowing the electrochemically driven NiR catalysis to be monitored. The activity of the NiR enzyme remains unperturbed by the immobilization. The rate-limiting step of the system is tentatively ascribed to the dissociation of the Paz/NiR complex. The electrochemical response of the system reports not only on the NiR catalysis and on interfacial electron transfer but also on the interaction between NiR and Paz.

A thermally regenerative ammonia battery with carbon-silver electrodes for converting low-grade waste heat to electricity

NASA Astrophysics Data System (ADS)

Rahimi, Mohammad; Kim, Taeyoung; Gorski, Christopher A.; Logan, Bruce E.

2018-01-01

Thermally regenerative ammonia batteries (TRABs) have shown great promise as a method to convert low-grade waste heat into electrical power, with power densities an order of magnitude higher than other approaches. However, previous TRABs based on copper electrodes suffered from unbalanced anode dissolution and cathode deposition rates during discharging cycles, limiting practical applications. To produce a TRAB with stable and reversible electrode reactions over many cycles, inert carbon electrodes were used with silver salts. In continuous flow tests, power production was stable over 100 discharging cycles, demonstrating excellent reversibility. Power densities were 23 W m-2-electrode area in batch tests, which was 64% higher than that produced in parallel tests using copper electrodes, and 30 W m-2 (net energy density of 490 Wh m-3-anolyte) in continuous flow tests. While this battery requires the use a precious metal, an initial economic analysis of the system showed that the cost of the materials relative to energy production was 220 per MWh, which is competitive with energy production from other non-fossil fuel sources. A substantial reduction in costs could be obtained by developing less expensive anion exchange membranes.

Confined ion energy >200 keV and increased fusion yield in a DPF with monolithic tungsten electrodes and pre-ionization

NASA Astrophysics Data System (ADS)

Lerner, Eric J.; Hassan, Syed M.; Karamitsos, Ivana; Von Roessel, Fred

2017-10-01

To reduce impurities in the dense plasma focus FF-1 device, we used monolithic tungsten electrodes with pre-ionization. With this new set-up, we demonstrated a three-fold reduction of impurities by mass and a ten-fold reduction by ion number. FF-1 produced a 50% increase in fusion yield over our previous copper electrodes, both for a single shot and for a mean of ten consecutive shots with the same conditions. These results represent a doubling of fusion yield as compared with any other plasma focus device with the same 60 kJ energy input. In addition, FF-1 produced a new single-shot record of 240 ± 20 keV for mean ion energy, a record for any confined fusion plasma, using any device, and a 50% improvement in ten-shot mean ion energy. With a deuterium-nitrogen mix and corona-discharge pre-ionization, we were also able to reduce the standard deviation in the fusion yield to about 15%, a four-fold reduction over the copper-electrode results. We intend to further reduce impurities with new experiments using microwave treatment of tungsten electrodes, followed by the use of beryllium electrodes.

Electrochemical studies of mesoporous and copper-modified mesoporous TiO2 -anode material

NASA Astrophysics Data System (ADS)

Ajay Kumar, R.; Venkateswara Rao, A.; Rajesh, Ch.

2018-05-01

Herein, we developed a method to synthesize highly ordered mesoporous TiO2 (MT) and copper-modified M- TiO2 (CMT) with a high surface area by the hydrothermal method using Pluronic P-123 as a surfactant at 150 ° C. CMT with different copper concentrations (0.1, 0.2 and 0.3%) was synthesized. The structural characterization studies revealed that MT and CMT particles are in anatase phase. The average particle size was found to be 24± 0.8 nm for MT and that of CMT was 25± 0.6 , 27± 0.4 and 28± 0.3 nm, respectively. The presence of ordered spherical MT and CMT particles with uniform size distribution was confirmed by performing morphological studies using FE-SEM. Optical absorption studies indicate the presence of copper because of the red shift in the band gap and also a broad peak around 800nm when compared with MT. EIS studies point out an increase in conductivity from MT through 0.3% CMT by a decrease in the charge transfer resistance. Further, charge-discharge studies were carried on this material at room temperature for lithium-ion battery applications. CMT with 0.3% copper showed high initial discharge capacity and better cyclability. The results indicate that this material can act as a promising negative electrode.

Flower-like Copper Cobaltite Nanosheets on Graphite Paper as High-Performance Supercapacitor Electrodes and Enzymeless Glucose Sensors.

PubMed

Liu, Shude; Hui, K S; Hui, K N

2016-02-10

Flower-like copper cobaltite (CuCo2O4) nanosheets anchored on graphite paper have been synthesized using a facile hydrothermal method followed by a postannealing treatment. Supercapacitor electrodes employing CuCo2O4 nanosheets exhibit an enhanced capacitance of 1131 F g(-1) at a current density of 1 A g(-1) compared with previously reported supercapacitor electrodes. The CuCo2O4 electrode delivers a specific capacitance of up to 409 F g(-1) at a current density of as high as 50 A g(-1), and a good long-term cycling stability, with 79.7% of its specific capacitance retained after 5000 cycles at 10 A g(-1). Furthermore, the as-prepared CuCo2O4 nanosheets on graphite paper can be fabricated as electrodes and used as enzymeless glucose sensors, which exhibit good sensitivity (3.625 μA μM(-1) cm(-2)) and an extraordinary linear response ranging up to 320 μM with a low detection limit (5 μM).

Acetylene-sourced CVD-synthesised catalytically active graphene for electrochemical biosensing.

PubMed

Osikoya, Adeniyi Olugbenga; Parlak, Onur; Murugan, N Arul; Dikio, Ezekiel Dixon; Moloto, Harry; Uzun, Lokman; Turner, Anthony Pf; Tiwari, Ashutosh

2017-03-15

In this study, we have demonstrated the use of chemical vapour deposition (CVD) grown-graphene to develop a highly-ordered graphene-enzyme electrode for electrochemical biosensing. The graphene sheets were deposited on 1.00mm thick copper sheet at 850°C using acetylene (C 2 H 2 ) as carbon source in an argon (Ar) and nitrogen (N 2 ) atmosphere. An anionic surfactant was used to increase wettability and hydrophilicity of graphene; thereby facilitating the assembly of biomolecules on the electrode surface. Meanwhile, the theoretical calculations confirmed the successful modification of hydrophobic nature of graphene through the anionic surface assembly, which allowed high-ordered immobilisation of glucose oxidase (GOx) on the graphene. The electrochemical sensing activities of the graphene-electrode was explored as a model for bioelectrocatalysis. The bioelectrode exhibited a linear response to glucose concentration ranging from 0.2 to 9.8mM, with sensitivity of 0.087µA/µM/cm 2 and a detection limit of 0.12µM (S/N=3). This work sets the stage for the use of acetylene-sourced CVD-grown graphene as a fundamental building block in the fabrication of electrochemical biosensors and other bioelectronic devices. Copyright © 2016 Elsevier B.V. All rights reserved.

Infrared particle detection for battery electrode foils

NASA Astrophysics Data System (ADS)

Just, P.; Ebert, L.; Echelmeyer, T.; Roscher, M. A.

2013-11-01

Failures of electrochemical cells caused by internal shorts still are an important issue to be faced by the cell manufacturers and their customers. A major cause for internal shorts are contaminated electrode foils. These contaminations have to be detected securely via a non-destructive inspection technique integrated into the electrode manufacturing process. While optical detection already is state of the art, infrared detection of particles finds a new field of application in the battery electrode manufacturing process. This work presents two approaches focusing on electrode inspection by electromagnetic radiation (visible and infrared). Copper foils with a carbon based coating were intentionally contaminated by slivers of aluminum and copper as well as by abraded coating particles. Optical excitation by a flash and a luminescent lamp was applied at different angles in order to detect the reflected visible radiation. A laser impulse was used to heat up the specimen for infrared inspection. Both approaches resulted in setups providing a high contrast between contaminations and the coated electrode foil. It is shown that infrared detection offers a higher security thanks to its reliance on absorbance and emissivity instead of reflectivity as it is used for optical detection. Infrared Detection offers a potential since it is hardly influenced by the particle's shape and orientation and the electrode's waviness.

Flow injection analysis of picric acid explosive using a copper electrode as electrochemical detector.

PubMed

Junqueira, João R C; de Araujo, William R; Salles, Maiara O; Paixão, Thiago R L C

2013-01-30

A simple and fast electrochemical method for quantitative analysis of picric acid explosive (nitro-explosive) based on its electrochemical reduction at copper surfaces is reported. To achieve a higher sample throughput, the electrochemical sensor was adapted in a flow injection system. Under optimal experimental conditions, the peak current response increases linearly with picric acid concentration over the range of 20-300 μmol L(-1). The repeatability of the electrode response in the flow injection analysis (FIA) configuration was evaluated as 3% (n=10), and the detection limit of the method was estimated to be 6.0 μmol L(-1) (S/N=3). The sample throughput under optimised conditions was estimated to be 550 samples h(-1). Peroxide explosives like triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD) were tested as potential interfering substances for the proposed method, and no significant interference by these explosives was noticed. The proposed method has interesting analytical parameters, environmental applications, and low cost compared with other electroanalytical methods that have been reported for the quantification of picric acid. Additionally, the possibility to develop an in situ device for the detection of picric acid using a disposable sensor was evaluated. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

Tunable reaction potentials in open framework nanoparticle battery electrodes for grid-scale energy storage.

PubMed

Wessells, Colin D; McDowell, Matthew T; Peddada, Sandeep V; Pasta, Mauro; Huggins, Robert A; Cui, Yi

2012-02-28

The electrical energy grid has a growing need for energy storage to address short-term transients, frequency regulation, and load leveling. Though electrochemical energy storage devices such as batteries offer an attractive solution, current commercial battery technology cannot provide adequate power, and cycle life, and energy efficiency at a sufficiently low cost. Copper hexacyanoferrate and nickel hexacyanoferrate, two open framework materials with the Prussian Blue structure, were recently shown to offer ultralong cycle life and high-rate performance when operated as battery electrodes in safe, inexpensive aqueous sodium ion and potassium ion electrolytes. In this report, we demonstrate that the reaction potential of copper-nickel alloy hexacyanoferrate nanoparticles may be tuned by controlling the ratio of copper to nickel in these materials. X-ray diffraction, TEM energy dispersive X-ray spectroscopy, and galvanostatic electrochemical cycling of copper-nickel hexacyanoferrate reveal that copper and nickel form a fully miscible solution at particular sites in the framework without perturbing the structure. This allows copper-nickel hexacyanoferrate to reversibly intercalate sodium and potassium ions for over 2000 cycles with capacity retentions of 100% and 91%, respectively. The ability to precisely tune the reaction potential of copper-nickel hexacyanoferrate without sacrificing cycle life will allow the development of full cells that utilize the entire electrochemical stability window of aqueous sodium and potassium ion electrolytes.

Copper(II) binding by dissolved organic matter: Importance of the copper-to-dissolved organic matter ratio and implications for the Biotic Ligand Model

USGS Publications Warehouse

Craven, Alison M.; Aiken, George R.; Ryan, Joseph N.

2012-01-01

The ratio of copper to dissolved organic matter (DOM) is known to affect the strength of copper binding by DOM, but previous methods to determine the Cu2+–DOM binding strength have generally not measured binding constants over the same Cu:DOM ratios. In this study, we used a competitive ligand exchange–solid-phase extraction (CLE-SPE) method to determine conditional stability constants for Cu2+–DOM binding at pH 6.6 and 0.01 M ionic strength over a range of Cu:DOM ratios that bridge the detection windows of copper-ion-selective electrode and voltammetry measurements. As the Cu:DOM ratio increased from 0.0005 to 0.1 mg of Cu/mg of DOM, the measured conditional binding constant (cKCuDOM) decreased from 1011.5 to 105.6 M–1. A comparison of the binding constants measured by CLE-SPE with those measured by copper-ion-selective electrode and voltammetry demonstrates that the Cu:DOM ratio is an important factor controlling Cu2+–DOM binding strength even for DOM isolates of different types and different sources and for whole water samples. The results were modeled with Visual MINTEQ and compared to results from the biotic ligand model (BLM). The BLM was found to over-estimate Cu2+ at low total copper concentrations and under-estimate Cu2+ at high total copper concentrations.

Flexible Asymmetric Solid-State Supercapacitors by Highly Efficient 3D Nanostructured α-MnO2 and h-CuS Electrodes.

PubMed

Patil, Amar M; Lokhande, Abhishek C; Shinde, Pragati A; Lokhande, Chandrakant D

2018-05-16

A simplistic and economical chemical way has been used to prepare highly efficient nanostructured, manganese oxide (α-MnO 2 ) and hexagonal copper sulfide (h-CuS) electrodes directly on cheap and flexible stainless steel sheets. Flexible solid-state α-MnO 2 /flexible stainless steel (FSS)/polyvinyl alcohol (PVA)-LiClO 4 /h-CuS/FSS asymmetric supercapacitor (ASC) devices have been fabricated using PVA-LiClO 4 gel electrolyte. Highly active surface areas of α-MnO 2 (75 m 2 g -1 ) and h-CuS (83 m 2 g -1 ) electrodes contribute to more electrochemical reactions at the electrode and electrolyte interface. The ASC device has a prolonged working potential of +1.8 V and accomplishes a capacitance of 109.12 F g -1 at 5 mV s -1 , energy density of 18.9 Wh kg -1 , and long-term electrochemical cycling with a capacity retention of 93.3% after 5000 cycles. Additionally, ASC devices were successful in glowing seven white-light-emitting diodes for more than 7 min after 30 s of charging. Outstandingly, real practical demonstration suggests "ready-to-sell" products for industries.

Evaluating the electrical discharge machining (EDM) parameters with using carbon nanotubes

NASA Astrophysics Data System (ADS)

Sari, M. M.; Noordin, M. Y.; Brusa, E.

2012-09-01

Electrical discharge machining (EDM) is one of the most accurate non traditional manufacturing processes available for creating tiny apertures, complex or simple shapes and geometries within parts and assemblies. Performance of the EDM process is usually evaluated in terms of surface roughness, existence of cracks, voids and recast layer on the surface of product, after machining. Unfortunately, the high heat generated on the electrically discharged material during the EDM process decreases the quality of products. Carbon nanotubes display unexpected strength and unique electrical and thermal properties. Multi-wall carbon nanotubes are therefore on purpose added to the dielectric used in the EDM process to improve its performance when machining the AISI H13 tool steel, by means of copper electrodes. Some EDM parameters such as material removal rate, electrode wear rate, surface roughness and recast layer are here first evaluated, then compared to the outcome of EDM performed without using nanotubes mixed to the dielectric. Independent variables investigated are pulse on time, peak current and interval time. Experimental evidences show that EDM process operated by mixing multi-wall carbon nanotubes within the dielectric looks more efficient, particularly if machining parameters are set at low pulse of energy.

Copper atomic-scale transistors

PubMed Central

Kavalenka, Maryna N; Röger, Moritz; Albrecht, Daniel; Hölscher, Hendrik; Leuthold, Jürgen

2017-01-01

We investigated copper as a working material for metallic atomic-scale transistors and confirmed that copper atomic-scale transistors can be fabricated and operated electrochemically in a copper electrolyte (CuSO4 + H2SO4) in bi-distilled water under ambient conditions with three microelectrodes (source, drain and gate). The electrochemical switching-on potential of the atomic-scale transistor is below 350 mV, and the switching-off potential is between 0 and −170 mV. The switching-on current is above 1 μA, which is compatible with semiconductor transistor devices. Both sign and amplitude of the voltage applied across the source and drain electrodes (U bias) influence the switching rate of the transistor and the copper deposition on the electrodes, and correspondingly shift the electrochemical operation potential. The copper atomic-scale transistors can be switched using a function generator without a computer-controlled feedback switching mechanism. The copper atomic-scale transistors, with only one or two atoms at the narrowest constriction, were realized to switch between 0 and 1G 0 (G 0 = 2e2/h; with e being the electron charge, and h being Planck’s constant) or 2G 0 by the function generator. The switching rate can reach up to 10 Hz. The copper atomic-scale transistor demonstrates volatile/non-volatile dual functionalities. Such an optimal merging of the logic with memory may open a perspective for processor-in-memory and logic-in-memory architectures, using copper as an alternative working material besides silver for fully metallic atomic-scale transistors. PMID:28382242

Spatially resolved, substrate-induced rectification in C 60 bilayers on copper

DOE PAGES

Smerdon, J. A.; Darancet, P.; Guest, J. R.

2017-02-22

Here, we demonstrate rectification ratios ( RR) of ≳1000 at biases of 1.3 V in bilayers of C 60 deposited on copper. Using scanning tunneling spectroscopy and first-principles calculations, we show that the strong coupling between C 60 and the Cu(111) surface leads to the metallization of the bottom C 60 layer, while the molecular orbitals of the top C60 are essentially unaffected. Due to this substrate-induced symmetry breaking and to a tunneling transport mechanism, the system behaves as a hole-blocking layer, with a spatial dependence of the onset voltage on intra-layer coordination. Together with previous observations of strong electron-blockingmore » character of pentacene/C 60 bilayers on Cu(111), this work further demonstrates the potential of strongly hybridized, C 60-coated electrodes to harness the electrical functionality of molecular components.« less

New concept to remove heavy metals from liquid waste based on electrochemical pH-switchable immobilized ligands

NASA Astrophysics Data System (ADS)

Pascal, Viel; Laetitia, Dubois; Joël, Lyskawa; Marc, Sallé; Serge, Palacin

2007-01-01

Absorption on resins is often used as secondary step in the treatment of water-based effluents, in order to reach very low concentrations. The separation of the trapped effluents from the resins and the regeneration of the resins for further use create wide volumes of secondary effluents coming from the washings of the resins with chemical reagents. We propose an alternative solution based on a "surface strategy" through adsorption phenomena and electrical control of the expulsion stage. The final goal is to limit or ideally to avoid the use of chemical reagents at the expulsion (or regeneration) stage of the depolluting process. Heavy metal ions were captured on active filters composed by a conducting surface covered by poly-4-vinylpyridine (P 4VP). Due to pyridine groups those polymer films have chelating properties for copper ions. Our strategy for electrical triggering of the copper expulsion in aqueous medium is based on pH sensitive chelating groups. Applying moderate electro-oxidizing conditions generates acidic conditions in the vicinity of the electrode, i.e. "inside" the polymer film. This allows a "switch-off" of the complexing properties of the film from the basic form of pyridine to pyridinium. Interestingly, no buffer washing is necessary to restore (or "switch-on") the complexing properties of the polymer film because the pH of the external medium is left unchanged by the electrochemical effect that affects only the vicinity of the electrode. Switch-on/switch-off cycles are followed and attested by IR spectroscopy and EQCM method.

Printed silver nanowire antennas with low signal loss at high-frequency radio

NASA Astrophysics Data System (ADS)

Komoda, Natsuki; Nogi, Masaya; Suganuma, Katsuaki; Kohno, Kazuo; Akiyama, Yutaka; Otsuka, Kanji

2012-05-01

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.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. Electronic supplementary information (ESI) available: Operation of R/C car with a silver nanowire monopole antenna. See DOI: 10.1039/c2nr30485f

Metallic sulfide additives for positive electrode material within a secondary electrochemical cell

DOEpatents

Walsh, William J.; McPheeters, Charles C.; Yao, Neng-ping; Koura, Kobuyuki

1976-01-01

An improved active material for use within the positive electrode of a secondary electrochemical cell includes a mixture of iron disulfide and a sulfide of a polyvalent metal. Various metal sulfides, particularly sulfides of cobalt, nickel, copper, cerium and manganese, are added in minor weight proportion in respect to iron disulfide for improving the electrode performance and reducing current collector requirements.

Synthesis, Spray Deposition, and Hot-Press Transfer of Copper Nanowires for Flexible Transparent Electrodes.

PubMed

Deshmukh, Rupali; Calvo, Micha; Schreck, Murielle; Tervoort, Elena; Sologubenko, Alla S; Niederberger, Markus

2018-06-20

We report a solution-phase approach to the synthesis of crystalline copper nanowires (Cu NWs) with an aspect ratio >1000 via a new catalytic mechanism comprising copper ions. The synthesis involves the reaction between copper(II) chloride and copper(II) acetylacetonate in a mixture of oleylamine and octadecene. Reaction parameters such as the molar ratio of precursors as well as the volume ratio of solvents offer the possibility to tune the morphology of the final product. A simple low-cost spray deposition method was used to fabricate Cu NW films on a glass substrate. Post-treatment under reducing gas (5% H 2 + 95% N 2 ) atmosphere resulted in Cu NW films with a low sheet resistance of 24.5 Ω/sq, a transmittance of T = 71% at 550 nm (including the glass substrate), and a high oxidation resistance. Moreover, the conducting Cu NW networks on a glass substrate can easily be transferred onto a polycarbonate substrate using a simple hot-press transfer method without compromising on the electrical performance. The resulting flexible transparent electrodes show excellent flexibility ( R/ R o < 1.28) upon bending to curvatures of 1 mm radius.

High-Voltage MOSFET Switching Circuit

NASA Technical Reports Server (NTRS)

Jensen, Kenneth A.

1995-01-01

Circuit reliably switches power at supply potential of minus 1,500 V, with controlled frequency and duty cycle. Used in argon-plasma ion-bombardment equipment for texturing copper electrodes, as described in "Texturing Copper To Reduce Secondary Emission of Electrons" (LEW-15898), also adapted to use in powering gaseous flash lamps and stroboscopes.

Acetaldehyde as an intermediate in the electroreduction of carbon monoxide to ethanol on oxide-derived copper

DOE PAGES

Bertheussen, Erlend; Verdaguer-Casadevall, Arnau; Ravasio, Davide; ...

2015-12-21

Oxide-derived copper (OD-Cu) electrodes exhibit unprecedented CO reduction performance towards liquid fuels, producing ethanol and acetate with >50 % Faradaic efficiency at -0.3 V (vs. RHE). By using static headspace-gas chromatography for liquid phase analysis, we identify acetaldehyde as a minor product and key intermediate in the electroreduction of CO to ethanol on OD-Cu electrodes. Acetaldehyde is produced with a Faradaic efficiency of ≈5 % at -0.33 V (vs. RHE). We show that acetaldehyde forms at low steady-state concentrations, and that free acetaldehyde is difficult to detect in alkaline solutions using NMR spectroscopy, requiring alternative methods for detection and quantification.more » Our results indicate an important step towards understanding the CO reduction mechanism on OD-Cu electrodes.« less

Total Copper Analyzer for Rapid In Situ Characterization of Effluent Discharges

DTIC Science & Technology

2006-10-03

acidification , digestion, and measurement of copper with a specialized jalpaite copper ion-selective electrode (Cu-ISE). The preprocessed sensor data...analysis. This is in contrast to the temperature conditions at SBWWTP, where the TCA was deployed in a plastic hut on open grounds. The daily range...GFAA Spectroscopy” (U.S. EPA, 1992). In order to accomplish this goal, the TCA includes in-line automatic acidification , fast digestion of the

Electrical Nanocontact Between Bismuth Nanowire Edges and Electrodes

NASA Astrophysics Data System (ADS)

Murata, Masayuki; Nakamura, Daiki; Hasegawa, Yasuhiro; Komine, Takashi; Uematsu, Daisuke; Nakamura, Shinichiro; Taguchi, Takashi

2010-09-01

Three methods for attaching electrodes to a bismuth nanowire sample were investigated. In the first and second methods, thin layers of titanium and copper were deposited by ion plating under vacuum onto the edge surface of individual bismuth nanowire samples that were encapsulated in a quartz template. Good electrical contact between the electrodes and the nanowire was achieved using silver epoxy and conventional solder on the thin-film layers in the first and second methods, respectively. In the third method, a low-melting-point solder was utilized and was also successful in achieving good electrical contact in air atmosphere. The connection methods showed no difference in terms of resistivity temperature dependence or Seebeck coefficient. The third method has an advantage in that nanocontact is easily achieved; however, diffusion of the solder into the nanowire allows contamination near the melting point of the solder. In the first and second methods, the thin-film layer enabled electrical contact to be more safely achieved than the direct contact used in the third method, because the thin-film layer prevented diffusion of binder components.

Metal-free, flexible triboelectric generator based on MWCNT mesh film and PDMS layers

NASA Astrophysics Data System (ADS)

Hwang, Hayoung; Lee, Kang Yeol; Shin, Dongjoon; Shin, Jungho; Kim, Sangtae; Choi, Wonjoon

2018-06-01

We demonstrate a metal-free triboelectric energy harvester consisted of MWCNT mesh film and PDMS layer. Upon touch from a finger, the single electrode-mode energy harvester generates up to 27.0 W/m2 output power at 10 MΩ matched impedance. The device generates stable power upon touch by bare fingers or gloved fingers. Using copper counter electrode results in decreased power output, due to the weaker tendency in triboelectrification. The power output also scales with the pressure applied by the finger. The intertwined, condensed MWCNT network acts as a flexible yet effective current collector, with resistance across the device less than 10 Ω. This current collector possesses strong corrosion resistance and stability against potential oxidation, while its metal counterpart may undergo oxidation over extended exposure to air or frequent fracture upon straining. The flexible device form may be applied to various curved or irregular surfaces that undergo frequent human touches.

Nanographene synthesized in triple-phase plasmas as a highly durable support of catalysts for polymer electrolyte fuel cells

NASA Astrophysics Data System (ADS)

Amano, Tomoki; Kondo, Hiroki; Takeda, Keigo; Ishikawa, Kenji; Hiramatsu, Mineo; Sekine, Makoto; Hori, Masaru

2018-04-01

Nanographene was synthesized in triple-phase plasmas comprising a gaseous phase, a gas-liquid boundary layer, and an in-liquid phase using a setup in which one electrode was placed in the gaseous phase while the other was immersed in the liquid phase. The triple-phase plasmas were generated using a pure alcohol, such as ethanol, 1-propanol, or 1-butanol, by applying a high voltage to a pair of electrodes made of copper or graphite. The nanographene synthesized using ethanol had high durability and thus could serve as a catalyst support in polymer electrolyte fuel cells (PEFCs). The PEFCs exhibited low degradation rates in the high-potential cycle test of a half-cell, as a result of which, a loss of only 10% was observed in the effective electrochemical surface area of Pt, even after 10,000 cycles.

Metal vapor laser including hot electrodes and integral wick

DOEpatents

Ault, Earl R.; Alger, Terry W.

1995-01-01

A metal vapor laser, specifically one utilizing copper vapor, is disclosed herein. This laser utilizes a plasma tube assembly including a thermally insulated plasma tube containing a specific metal, e.g., copper, and a buffer gas therein. The laser also utilizes means including hot electrodes located at opposite ends of the plasma tube for electrically exciting the metal vapor and heating its interior to a sufficiently high temperature to cause the metal contained therein to vaporize and for subjecting the vapor to an electrical discharge excitation in order to lase. The laser also utilizes external wicking arrangements, that is, wicking arrangements located outside the plasma tube.

Porous dendritic copper: an electrocatalyst for highly selective CO2 reduction to formate in water/ionic liquid electrolyte.

PubMed

Huan, Tran Ngoc; Simon, Philippe; Rousse, Gwenaëlle; Génois, Isabelle; Artero, Vincent; Fontecave, Marc

2017-01-01

Copper is currently extensively studied because it provides promising electrodes for carbon dioxide electroreduction. The original combination, reported here, of a nanostructured porous dendritic Cu-based material, characterized by electron microcopy (SEM, TEM) and X-ray diffraction methods, and a water/ionic liquid mixture as the solvent, contributing to CO 2 solubilization and activation, results in a remarkably efficient (large current densities at low overpotentials), stable and selective (large faradic yields) electrocatalytic system for the conversion of CO 2 into formic acid, a product with a variety of uses. These results provide new directions for the further improvement of Cu electrodes.

Metal vapor laser including hot electrodes and integral wick

DOEpatents

Ault, E.R.; Alger, T.W.

1995-03-07

A metal vapor laser, specifically one utilizing copper vapor, is disclosed herein. This laser utilizes a plasma tube assembly including a thermally insulated plasma tube containing a specific metal, e.g., copper, and a buffer gas therein. The laser also utilizes means including hot electrodes located at opposite ends of the plasma tube for electrically exciting the metal vapor and heating its interior to a sufficiently high temperature to cause the metal contained therein to vaporize and for subjecting the vapor to an electrical discharge excitation in order to lase. The laser also utilizes external wicking arrangements, that is, wicking arrangements located outside the plasma tube. 5 figs.

Ultrathin nickel hydroxide on carbon coated 3D-porous copper structures for high performance supercapacitors.

PubMed

Kang, Kyeong-Nam; Kim, Ik-Hee; Ramadoss, Ananthakumar; Kim, Sun-I; Yoon, Jong-Chul; Jang, Ji-Hyun

2018-01-03

An ultrathin nickel hydroxide layer electrodeposited on a carbon-coated three-dimensional porous copper structure (3D-C/Cu) is suggested as an additive and binder-free conductive electrode with short electron path distances, large electrochemical active sites, and improved structural stability, for high performance supercapacitors. The 3D-porous copper structure (3D-Cu) provides high electrical conductivity and facilitates electron transport between the Ni(OH) 2 active materials and the current collector of the Ni-plate. A carbon coating was applied to the 3D-Cu to prevent the oxidation of Cu, without degrading the electron transport behavior of the 3D-Cu. The 3D-Ni(OH) 2 /C/Cu exhibited a high specific capacitance of 1860 F g -1 at 1 A g -1 , and good cycling performance, with an 86.5% capacitance retention after 10 000 cycles. When tested in a two-electrode system, an asymmetric supercapacitor exhibited an energy density of 147.9 W h kg -1 and a power density of 37.0 kW kg -1 . These results open a new area of ultrahigh-performance supercapacitors, supported by 3D-Cu electrodes.

Machinability of nickel based alloys using electrical discharge machining process

NASA Astrophysics Data System (ADS)

Khan, M. Adam; Gokul, A. K.; Bharani Dharan, M. P.; Jeevakarthikeyan, R. V. S.; Uthayakumar, M.; Thirumalai Kumaran, S.; Duraiselvam, M.

2018-04-01

The high temperature materials such as nickel based alloys and austenitic steel are frequently used for manufacturing critical aero engine turbine components. Literature on conventional and unconventional machining of steel materials is abundant over the past three decades. However the machining studies on superalloy is still a challenging task due to its inherent property and quality. Thus this material is difficult to be cut in conventional processes. Study on unconventional machining process for nickel alloys is focused in this proposed research. Inconel718 and Monel 400 are the two different candidate materials used for electrical discharge machining (EDM) process. Investigation is to prepare a blind hole using copper electrode of 6mm diameter. Electrical parameters are varied to produce plasma spark for diffusion process and machining time is made constant to calculate the experimental results of both the material. Influence of process parameters on tool wear mechanism and material removal are considered from the proposed experimental design. While machining the tool has prone to discharge more materials due to production of high energy plasma spark and eddy current effect. The surface morphology of the machined surface were observed with high resolution FE SEM. Fused electrode found to be a spherical structure over the machined surface as clumps. Surface roughness were also measured with surface profile using profilometer. It is confirmed that there is no deviation and precise roundness of drilling is maintained.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nehm, F., E-mail: frederik.nehm@iapp.de; Müller-Meskamp, L.; Klumbies, H.

A major failure mechanism is identified in electrical calcium corrosion tests for quality assessment of high-end application moisture barriers. Accelerated calcium corrosion is found at the calcium/electrode junction, leading to an electrical bottleneck. This causes test failure not related to overall calcium loss. The likely cause is a difference in electrochemical potential between the aluminum electrodes and the calcium sensor, resulting in a corrosion element. As a solution, a thin, full-area copper layer is introduced below the calcium, shifting the corrosion element to the calcium/copper junction and inhibiting bottleneck degradation. Using the copper layer improves the level of sensitivity formore » the water vapor transmission rate (WVTR) by over one order of magnitude. Thin-film encapsulated samples with 20 nm of atomic layer deposited alumina barriers this way exhibit WVTRs of 6 × 10{sup −5} g(H{sub 2}O)/m{sup 2}/d at 38 °C, 90% relative humidity.« less

Betavoltaics using scandium tritide and contact potential difference

NASA Astrophysics Data System (ADS)

Liu, Baojun; Chen, Kevin P.; Kherani, Nazir P.; Zukotynski, Stefan; Antoniazzi, Armando B.

2008-02-01

Tritium-powered betavoltaic micropower sources using contact potential difference (CPD) are demonstrated. Thermally stable scandium tritide thin films with a surface activity of 15mCi/cm2 were used as the beta particle source. The electrical field created by the work function difference between the ScT film and a platinum or copper electrode was used to separate the beta-generated electrical charge carriers. Open circuit voltages of 0.5 and 0.16V and short circuit current densities of 2.7 and 5.3nA/cm2 were achieved for gaseous and solid dielectric media-based CPD cells, respectively.

Simple Potentiometric Determination of Reducing Sugars

ERIC Educational Resources Information Center

Moresco, Henry; Sanson, Pedro; Seoane, Gustavo

2008-01-01

In this article a potentiometric method for reducing sugar quantification is described. Copper(II) ion reacts with the reducing sugar (glucose, fructose, and others), and the excess is quantified using a copper wire indicator electrode. In order to accelerate the kinetics of the reaction, working conditions such as pH and temperature must be…

Chemical Intercalation of Topological Insulator Grid Nanostructures for High-Performance Transparent Electrodes.

PubMed

Guo, Yunfan; Zhou, Jinyuan; Liu, Yujing; Zhou, Xu; Yao, Fengrui; Tan, Congwei; Wu, Jinxiong; Lin, Li; Liu, Kaihui; Liu, Zhongfan; Peng, Hailin

2017-11-01

2D layered nanomaterials with strong covalent bonding within layers and weak van der Waals' interactions between layers have attracted tremendous interest in recent years. Layered Bi 2 Se 3 is a representative topological insulator material in this family, which holds promise for exploration of the fundamental physics and practical applications such as transparent electrode. Here, a simultaneous enhancement of optical transmittancy and electrical conductivity in Bi 2 Se 3 grid electrodes by copper-atom intercalation is presented. These Cu-intercalated 2D Bi 2 Se 3 electrodes exhibit high uniformity over large area and excellent stabilities to environmental perturbations, such as UV light, thermal fluctuation, and mechanical distortion. Remarkably, by intercalating a high density of copper atoms, the electrical and optical performance of Bi 2 Se 3 grid electrodes is greatly improved from 900 Ω sq -1 , 68% to 300 Ω sq -1 , 82% in the visible range; with better performance of 300 Ω sq -1 , 91% achieved in the near-infrared region. These unique properties of Cu-intercalated topological insulator grid nanostructures may boost their potential applications in high-performance optoelectronics, especially for infrared optoelectronic devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Composite electrodes for advanced electrochemical applications. Quarterly report for the period October 1, - December 31, 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovach, Chris

The electrochemical industry is one of the most highly energy intensive industries today. However, there have been no significant advances in the electrodes that these industries use. The dimensionally stable anode (DSA), which ELTECH introduced under a license agreement, has been the industry standard for the past twenty-five years. But, DSAs are nearing the end of their technological prevalence. The principal problems with DSAs include high capital and operating costs, and the proprietary nature of the technology. In addition, DSAs experience problems that include: contamination of the process solution by anode materials, failure when the electrocatalytic coating peels from underattack,more » generally low anode performance due to inherent limitations in operating current density, and short anode lifetime because of corrosion. The proposed innovation combines the low electrical resistance of copper with the corrosion resistance of electrically conductive diamond to achieve energy efficient, long-lifetime electrodes for electrochemistry. The proposed work will ultimately develop a composite electrode that consists of a copper substrate, a conductive diamond coating, and a catalytic precious metal coating. The scope of the current work includes preparation, testing, and evaluation of diamond-coated titanium electrodes.« less

Composite electrodes for advanced electrochemical applications. Quarterly report for the period July 1 - September 30, 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovach, Chris

The electrochemical industry is one of the most highly energy-intensive industries today. However, there have been no significant advances in the electrodes that these industries use. The dimensionally stable anode (DSA), which ELTECH introduced under a license agreement, has been the industry standard for the past twenty-five years. But, DSAs are nearing the end of their technological prevalence. The principal problems with DSAs include high capital and operating cost, and the proprietary nature of the technology. In addition, DSAs experience problems that include contamination of the process solution by anode materials, failure when the electrocatalytic coating peels from under attack,more » generally low anode performance due to inherent limitations in operating current density, and short anode lifetime because of corrosion. The proposed innovation combines the low electrical resistance of copper with the corrosion resistance of electrically conductive diamond to achieve energy-efficient, long-lifetime electrodes for electrochemistry. The proposed work will ultimately develop a composite electrode that consists of a copper substrate, a conductive diamond coating, and a catalytic precious metal coating. The scope of the current work includes preparation, testing, and evaluation of diamond-coated titanium electrodes.« less

Identification and Description of Geophysical Techniques.

DTIC Science & Technology

1980-11-01

electrodes are used for voltage measurements with the potentiometer. Current elec- trodes may be stainless-steel or copper rods, buried copper screens, drill...steel in a borehole, or buried metal culverts. Potential elec- trodes may be stainless steel rods or porous containers filled with copper sulfate...Granite 28-2,700 Diorite 47 Gabbro 68-2,370 Porphyry 47 Diabase 78-1,050 Basalt 680 Olivine-Diabase 2,000 1. Peridotite 12,500 I (1)Adapted from C. A

Interaction of CuS and sulfur in Li-S battery system

DOE PAGES

Sun, Ke; Su, Dong; Zhang, Qing; ...

2015-10-27

Lithium-Sulfur (Li-S) battery has been a subject of intensive research in recent years due to its potential to provide much higher energy density and lower cost than the current state of the art lithiumion battery technology. In this work, we have investigated Cupric Sulfide (CuS) as a capacitycontributing conductive additive to the sulfur electrode in a Li-S battery. Galvanostatic charge/discharge cycling has been used to compare the performance of both sulfur electrodes and S:CuS hybrid electrodes with various ratios. We found that the conductive CuS additive enhanced the utilization of the sulfur cathode under a 1C rate discharge. However, undermore » a C/10 discharge rate, S:CuS hybrid electrodes exhibited lower sulfur utilization in the first discharge and faster capacity decay in later cycles than a pure sulfur electrode due to the dissolution of CuS. The CuS dissolution is found to be the result of strong interaction between the soluble low order polysulfide Li 2S 3 and CuS. As a result, we identified the presence of conductive copper-containing sulfides at the cycled lithium anode surface, which may degrade the effectiveness of the passivation function of the solid-electrolyte-interphase (SEI) layer, accounting for the poor cycling performance of the S:CuS hybrid cells at low rate.« less

Surface structure influences contact killing of bacteria by copper

PubMed Central

Zeiger, Marco; Solioz, Marc; Edongué, Hervais; Arzt, Eduard; Schneider, Andreas S

2014-01-01

Copper kills bacteria rapidly by a mechanism that is not yet fully resolved. The antibacterial property of copper has raised interest in its use in hospitals, in place of plastic or stainless steel. On the latter surfaces, bacteria can survive for days or even weeks. Copper surfaces could thus provide a powerful accessory measure to curb nosocomial infections. We here investigated the effect of the copper surface structure on the efficiency of contact killing of Escherichia coli, an aspect which so far has received very little attention. It was shown that electroplated copper surfaces killed bacteria more rapidly than either polished copper or native rolled copper. The release of ionic copper was also more rapid from electroplated copper compared to the other materials. Scanning electron microscopy revealed that the bacteria nudged into the grooves between the copper grains of deposited copper. The findings suggest that, in terms of contact killing, more efficient copper surfaces can be engineered. PMID:24740976

Influence of Electrical Resistivity and Machining Parameters on Electrical Discharge Machining Performance of Engineering Ceramics

PubMed Central

Ji, Renjie; Liu, Yonghong; Diao, Ruiqiang; Xu, Chenchen; Li, Xiaopeng; Cai, Baoping; Zhang, Yanzhen

2014-01-01

Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al2O3 ceramic's EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al2O3 ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al2O3 ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al2O3 ceramic surface shows that the ZnO/Al2O3 ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge machining ZnO/Al2O3 ceramic. PMID:25364912

Inert electrode containing metal oxides, copper and noble metal

DOEpatents

Ray, Siba P.; Woods, Robert W.; Dawless, Robert K.; Hosler, Robert B.

2001-01-01

A cermet composite material is made by treating at an elevated temperature a mixture comprising a compound of iron and a compound of at least one other metal, together with an alloy or mixture of copper and a noble metal. The alloy or mixture preferably comprises particles having an interior portion containing more copper than noble metal and an exterior portion containing more noble metal than copper. The noble metal is preferably silver. The cermet composite material preferably includes alloy phase portions and a ceramic phase portion. At least part of the ceramic phase portion preferably has a spinel structure.

Inert electrode containing metal oxides, copper and noble metal

DOEpatents

Ray, Siba P.; Woods, Robert W.; Dawless, Robert K.; Hosler, Robert B.

2000-01-01

A cermet composite material is made by treating at an elevated temperature a mixture comprising a compound of iron and a compound of at least one other metal, together with an alloy or mixture of copper and a noble metal. The alloy or mixture preferably comprises particles having an interior portion containing more copper than noble metal and an exterior portion containing more noble metal than copper. The noble metal is preferably silver. The cermet composite material preferably includes alloy phase portions and a ceramic phase portion. At least part of the ceramic phase portion preferably has a spinel structure.

Probing the Active Surface Sites for CO Reduction on Oxide-Derived Copper Electrocatalysts

DOE PAGES

Verdaguer-Casadevall, Arnau; Li, Christina W.; Johansson, Tobias P.; ...

2015-07-30

CO electroreduction activity on oxide-derived Cu (OD-Cu) was found to correlate with metastable surface features that bind CO strongly. OD-Cu electrodes prepared by H 2 reduction of Cu 2O precursors reduce CO to acetate and ethanol with nearly 50% Faradaic efficiency at moderate overpotential. Temperature-programmed desorption of CO on OD-Cu revealed the presence of surface sites with strong CO binding that are distinct from the terraces and stepped sites found on polycrystalline Cu foil. After annealing at 350 °C, the surface-area corrected current density for CO reduction is 44-fold lower and the Faradaic efficiency is less than 5%. These changesmore » are accompanied by a reduction in the proportion of strong CO binding sites. Here, we propose that the active sites for CO reduction on OD-Cu surfaces are strong CO binding sites that are supported by grain boundaries. Uncovering these sites is a first step toward understanding the surface chemistry necessary for efficient CO electroreduction.« less

Critical Evaluation of State-of-the-Art In Situ Thermal Treatment Technologies for DNAPL Source Zone Treatment

DTIC Science & Technology

2010-01-01

from steel pipe , copper plate for heating distinct zones and sheet pile. Sheet pile electrodes allow for quick installation with little to no drilling...as electrodes. Electrodes constructed using Thermal Remediation Services - Electrical Resistance Heating ER-0314 18 Appendix B steel pipe are...who authored state- of-the-art descriptions for the most common in-situ thermal technologies currently employed:  Electrical Resistance Heating

A study on the effect of tool electrode thickness on MRR, and TWR in electrical discharge turning process

NASA Astrophysics Data System (ADS)

Gohil, Vikas; Puri, YM

2018-04-01

Turning by electrical discharge machining (EDM) is an emerging area of research. Generally, wire-EDM is used in EDM turning because it is not concerned with electrode tooling cost. In EDM turning wire electrode leaves cusps on the machined surface because of its small diameters and wire breakage which greatly affect the surface finish of the machined part. Moreover, one of the limitations of the process is low machining speed as compared to constituent processes. In this study, conventional EDM was employed for turning purpose in order to generate free-form cylindrical geometries on difficult-to-cut materials. Therefore, a specially designed turning spindle was mounted on a conventional die-sinking EDM machine to rotate the work piece. A conductive preshaped strip of copper as a forming tool is fed (reciprocate) continuously against the rotating work piece; thus, a mirror image of the tool is formed on the circumference of the work piece. In this way, an axisymmetric work piece can be made with small tools. The developed process is termed as the electrical discharge turning (EDT). In the experiments, the effect of machining parameters, such as pulse-on time, peak current, gap voltage and tool thickness on the MRR, and TWR were investigated and practical machining was carried out by turning of SS-304 stainless steel work piece.

Graphene decorated microelectrodes for simultaneous detection of ascorbic, dopamine, and folic acids by means of chemical vapor deposition

NASA Astrophysics Data System (ADS)

Namdar, N.; Hassanpour Amiri, M.; Dehghan Nayeri, F.; Gholizadeh, A.; Mohajerzadeh, S.

2015-09-01

In this paper, high quality and large area graphene layers were synthesized using thermal chemical vapour deposition on copper foil substrates. We use graphene incorporated electrodes to measure simultaneously ascorbic acid, dopamine and folic acid. Cyclic voltammetry and differential pulse voltammetry methods were used to evaluate electrochemical behaviour of the grown graphene layers. The graphene-modified electrode shows large electrochemical potential difference compared to bare gold electrodes with higher current responses. Also our fabricated electrodes configuration can be used easily for microfluidic analysis.

All-inorganic large-area low-cost and durable flexible perovskite solar cells using copper foil as a substrate.

PubMed

Abdollahi Nejand, B; Nazari, P; Gharibzadeh, S; Ahmadi, V; Moshaii, A

2017-01-05

Here, a low-cost perovskite solar cell using CuI and ZnO as the respective inorganic hole and electron transport layers is introduced. Copper foil is chosen as a cheap and low-weight conductive substrate which has a similar work function to ITO. Besides, copper foil is an interesting copper atom source for the growth of the upper cuprous iodide layer on copper foil. A spray coating of a transparent silver nanowire electrode is used as a top contact. The prepared device shows a maximum power conversion efficiency of 12.80% and long-term durability providing an environmentally and market friendly perovskite solar cell.

Solvothermal Synthesis of Three-Dimensional Hierarchical CuS Microspheres from a Cu-Based Ionic Liquid Precursor for High-Performance Asymmetric Supercapacitors.

PubMed

Zhang, Jing; Feng, Huijie; Yang, Jiaqin; Qin, Qing; Fan, Hongmin; Wei, Caiying; Zheng, Wenjun

2015-10-07

It is meaningful to exploit copper sulfide materials with desired structure as well as potential application due to their cheapness and low toxicity. A low-temperature and facile solvothermal method for preparing three-dimensional (3D) hierarchical covellite (CuS) microspheres from an ionic liquid precursor [Bmim]2Cu2Cl6 (Bmim = 1-butyl-3-methylimidazolium) is reported. The formation of CuS nanostructures was achieved by decomposition of intermediate complex Cu(Tu)3Cl (thiourea = Tu), which produced CuS microspheres with diameters of 2.5-4 μm assembled by nanosheets with thicknesses of 10-15 nm. The ionic liquid, as an "all-in-one" medium, played a key role for the fabrication and self-assembly of CuS nanosheets. The alkylimidazolium rings ([Bmim](+)) were found to adsorb onto the (001) facets of CuS crystals, which inhibited the crystal growth along the [001] direction, while the alkyl chain had influence on the assembly of CuS nanosheets. The CuS microspheres showed enhanced electrochemical performance and high stability for the application in supercapacitors due to intriguing structural design and large specific surface area. When this well-defined CuS electrode was assembled into an asymmetric supercapacitor (ASC) with an activated carbon (AC) electrode, the CuS//AC-ASC demonstrated good cycle performance (∼88% capacitance after 4000 cycles) and high energy density (15.06 W h kg(-1) at a power density of 392.9 W kg(-1)). This work provides new insights into the use of copper sulfide electrode materials for asymmetric supercapacitors and other electrochemical devices.

Pd-Cu/poly(o-Anisidine) nanocomposite as an efficient catalyst for formaldehyde oxidation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hosseini, Sayed Reza, E-mail: r.hosseini@umz.ac.ir; Raoof, Jahan-Bakhsh; Ghasemi, Shahram

Highlights: • o-Anisidine monomer was electro-polymerized at the pCPE surface in acid medium. • Palladium/copper NPs were prepared by galvanic replacement method at the POA/pCPE. • Pd-Cu NPs showed excellent electrocatalytic activity towards formaldehyde oxidation. • The bimetallic Pd-Cu NPs/POA nanocomposite showed satisfactory long-term stability. - Abstract: In this work, for the first time, the electrocatalytic oxidation of formaldehyde in 0.5 M sulfuric acid solution at spherical bimetallic palladium-copper nanoparticles (Pd-Cu NPs) deposited on the poly (o-Anisidine) film modified electrochemically pretreated carbon paste electrode (POA/pCPE) has been investigated. Highly porous POA film prepared by electropolymerization onto the pCPE was usedmore » as a potent support for deposition of the Pd-Cu NPs. The Pd-Cu NPs were prepared through spontaneous and irreversible reaction via galvanic replacement between Pd{sup II} ions and the Cu{sup 0} particles. The prepared Pd-Cu NPs were characterized by scanning electron microscopy, energy dispersive spectroscopy and electrochemical methods. The obtained results showed that the utilization of Cu nanoparticles and pretreatment technique enhances the electrocatalytic activity of the modified electrode towards formaldehyde oxidation. The influence of several parameters on formaldehyde oxidation as well as stability of the Pd-Cu/POA/pCPE has been investigated.« less

Computational evaluation of sub-nanometer cluster activity of singly exposed copper atom with various coordinative environment in catalytic CO2 transformation

NASA Astrophysics Data System (ADS)

Shanmugam, Ramasamy; Thamaraichelvan, Arunachalam; Ganesan, Tharumeya Kuppusamy; Viswanathan, Balasubramanian

2017-02-01

Metal cluster, at sub-nanometer level has a unique property in the activation of small molecules, in contrast to that of bulk surface. In the present work, singly exposed active site of copper metal cluster at sub-nanometer level was designed to arrive at the energy minimised configurations, binding energy, electrostatic potential map, frontier molecular orbitals and partial density of states. The ab initio molecular dynamics was carried out to probe the catalytic nature of the cluster. Further, the stability of the metal cluster and its catalytic activity in the electrochemical reduction of CO2 to CO were evaluated by means of computational hydrogen electrode via calculation of the free energy profile using DFT/B3LYP level of theory in vacuum. The activity of the cluster is ascertained from the fact that the copper atom, present in a two coordinative environment, performs a more selective conversion of CO2 to CO at an applied potential of -0.35 V which is comparatively lower than that of higher coordinative sites. The present study helps to design any sub-nano level metal catalyst for electrochemical reduction of CO2 to various value added chemicals.

Infrared and Raman spectroscopic studies of tris-[3-(trimethoxysilyl)propyl] isocyanurate, its sol-gel process, and coating on aluminum and copper.

PubMed

Li, Ying-Sing; Church, Jeffrey S; Woodhead, Andrea L; Vecchio, Nicolas E; Yang, Johnny

2014-11-11

Tris-[3-(trimethoxysilyl)propyl] isocyanurate (TTPI) has been used as a precursor to prepare a sol using ethanol as the solvent under acidic conditions. The sol-gel was applied for the surface treatment of aluminum and copper. Infrared and Raman spectra have been recorded for pure TTPI and the TTPI sol, xerogel and TTPI sol-gel coated metals. From the vibrational spectra, TTPI is likely to have the C1 point group. Vibrational assignments are suggested based on group frequencies, the expected reactions in the sol-gel process and the vibrational studies of some related molecules. From the experimental infrared spectra of xerogels annealed at different temperatures and from the thermal-gravimetric analysis, it is found that the TTPI xerogel decomposes at around 450°C with silica being the major decomposition product. A cyclic voltammetric study of the metal electrodes coated with different concentrations of TTPI ranging from 5% to 42% (v/v) has shown that the films with high concentrations of sol would provide better corrosion protection for aluminum and copper. Copyright © 2014 Elsevier B.V. All rights reserved.

Green synthesis and characterization of novel gold nanocomposites for electrochemical sensing applications.

PubMed

Tanwar, Shivani; Ho, Ja-an Annie; Magi, Emanuele

2013-12-15

Synthesis, characterization and application of Au-PANI-Calix and Au-PANI-Nap nanocomposites, is reported herein. An easy template free green synthesis is proposed and discussed for easy expediency. A variety of analytical techniques were used to characterize the nanocomposites: UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Dynamic light scattering (DLS), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS) were used to characterize the nanocomposites. Surface morphology was studied by transmission electron microscopy (TEM). The nanocomposites were immobilized on screen-printed electrode and showed electroactivity in neutral pH, making them promising candidates for various analytical applications. A sensitive and selective detection of Cu(2+) was perceived on the Au-PANI-Calix modified electrode with no interference from ions K(+), Ni(2+), Co(2+), Pb(2+), Cr(3+) with a detection limit of 10nM. The copper detection is facilitated for accessible ligation with 4-sulfocalix[4]arene, so as the Cu(II)-Calix complex formed. The electrode modified with Au-PANI-Nap showed sensing application towards H2O2 with a detection limit of 1 μM. The modified electrodes were reproducible and stable for 2 months. © 2013 Elsevier B.V. All rights reserved.

Facile Synthesis of Flower-Like Copper-Cobalt Sulfide as Binder-Free Faradaic Electrodes for Supercapacitors with Improved Electrochemical Properties

PubMed Central

Wang, Tianlei; Liu, Meitang; Ma, Hongwen

2017-01-01

Supercapacitors have been one of the highest potential candidates for energy storage because of their significant advantages beyond rechargeable batteries in terms of large power density, short recharging time, and long cycle lifespan. In this work, Cu–Co sulfides with uniform flower-like structure have been successfully obtained via a traditional two-step hydrothermal method. The as-fabricated Cu–Co sulfide vulcanized from precursor (P–Cu–Co sulfide) is able to deliver superior specific capacitance of 592 F g−1 at 1 A g−1 and 518 F g−1 at 10 A g−1 which are surprisingly about 1.44 times and 2.39 times higher than those of Cu–Co oxide electrode, respectively. At the same time, excellent cycling stability of P–Cu–Co sulfide is indicated by 90.4% capacitance retention at high current density of 10 A g−1 after 3000 cycles. Because of the introduction of sulfur during the vulcanization process, these new developed sulfides can get more flexible structure and larger reaction surface area, and will own richer redox reaction sites between the interfaces of active material/electrolyte. The uniform flower-like P–Cu–Co sulfide electrode materials will have more potential alternatives for oxides electrode materials in the future. PMID:28590417

Facile Synthesis of Flower-Like Copper-Cobalt Sulfide as Binder-Free Faradaic Electrodes for Supercapacitors with Improved Electrochemical Properties.

PubMed

Wang, Tianlei; Liu, Meitang; Ma, Hongwen

2017-06-07

Supercapacitors have been one of the highest potential candidates for energy storage because of their significant advantages beyond rechargeable batteries in terms of large power density, short recharging time, and long cycle lifespan. In this work, Cu-Co sulfides with uniform flower-like structure have been successfully obtained via a traditional two-step hydrothermal method. The as-fabricated Cu-Co sulfide vulcanized from precursor (P-Cu-Co sulfide) is able to deliver superior specific capacitance of 592 F g -1 at 1 A g -1 and 518 F g -1 at 10 A g -1 which are surprisingly about 1.44 times and 2.39 times higher than those of Cu-Co oxide electrode, respectively. At the same time, excellent cycling stability of P-Cu-Co sulfide is indicated by 90.4% capacitance retention at high current density of 10 A g -1 after 3000 cycles. Because of the introduction of sulfur during the vulcanization process, these new developed sulfides can get more flexible structure and larger reaction surface area, and will own richer redox reaction sites between the interfaces of active material/electrolyte. The uniform flower-like P-Cu-Co sulfide electrode materials will have more potential alternatives for oxides electrode materials in the future.

Seed-mediated synthesis of ultra-long copper nanowires and their application as transparent conducting electrodes

NASA Astrophysics Data System (ADS)

Kim, Hyunhong; Choi, Seong-Hyeon; Kim, Mijung; Park, Jang-Ung; Bae, Joonwon; Park, Jongnam

2017-11-01

Owing to a recent push toward one-dimensional nanomaterials, in this study, we report a seed-mediated synthetic strategy for copper nanowires (Cu NWs) production involving thermal decomposition of metal-surfactant complexes in an organic medium. Ultra-long Cu NWs with a high aspect ratio and uniform diameter were obtained by separating nucleation and growth steps. The underlying mechanism for nanowire formation was investigated, in addition, properties of the obtained Cu NWs were also characterized using diverse analysis techniques. The performance of resulting Cu NWs as transparent electrodes was demonstrated for potential application. This article can provide information on both new synthetic pathway and potential use of Cu NWs.

Electrochemically Protected Copper(I)-Catalyzed Azide-Alkyne Cycloaddition

PubMed Central

Hong, Vu; Udit, Andrew K.; Evans, Richard A.; Finn, M.G.

2012-01-01

The copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has found broad application in myriad fields. For the most demanding applications requiring high yields at low substrate concentrations, highly active but air-sensitive copper complexes must be used. We describe here the use of an electrochemical potential to maintain catalysts in the active Cu(I) oxidation state in the presence of air. The simple procedure efficiently achieves excellent yields of CuAAC products involving both small molecule and protein substrates without the use of potentially damaging chemical reducing agents. A new water-soluble carboxylated version of the popular tris(benzyltriazolylmethyl)amine (TBTA) ligand is described. Cyclic voltammetry revealed reversible or quasi-reversible electrochemical redox behavior of copper complexes of the TBTA derivative (2; E1/2 = 60 mV vs. Ag/AgCl), sulfonated bathophenanthroline (3; E1/2 = -60 mV), and sulfonated tris(benzimidazoylmethyl)amine (4; E1/2 ~ -70 mV), and showed catalytic turnover to be rapid relative to the voltammetry time scale. Under the influence of a -200 mV potential established using a reticulated vitreous carbon working electrode, CuSO4 and 3 formed a superior catalyst. Electrochemically-protected bioconjugations in air were performed using bacteriophage Qβ derivatized with azide moieties at surface lysine residues. The complete addressing of more than 600 reactive sites per particle was demonstrated within 12 hours of electrolysis with sub-stoichiometric quantities of Cu•3. PMID:18504727

Spray-Deposited Large-Area Copper Nanowire Transparent Conductive Electrodes and Their Uses for Touch Screen Applications.

PubMed

Chu, Hsun-Chen; Chang, Yen-Chen; Lin, Yow; Chang, Shu-Hao; Chang, Wei-Chung; Li, Guo-An; Tuan, Hsing-Yu

2016-05-25

Large-area conducting transparent conducting electrodes (TCEs) were prepared by a fast, scalable, and low-cost spray deposition of copper nanowire (CuNW) dispersions. Thin, long, and pure copper nanowires were obtained via the seed-mediated growth in an organic solvent-based synthesis. The mean length and diameter of nanowires are, respectively, 37.7 μm and 46 nm, corresponding to a high-mean-aspect ratio of 790. These wires were spray-deposited onto a glass substrate to form a nanowire conducting network which function as a TCE. CuNW TCEs exhibit high-transparency and high-conductivity since their relatively long lengths are advantageous in lowering in the sheet resistance. For example, a 2 × 2 cm(2) transparent nanowire electrode exhibits transmittance of T = 90% with a sheet resistance as low as 52.7 Ω sq(-1). Large-area sizes (>50 cm(2)) of CuNW TCEs were also prepared by the spray coating method and assembled as resistive touch screens that can be integrated with a variety of devices, including LED lighting array, a computer, electric motors, and audio electronic devices, showing the capability to make diverse sizes and functionalities of CuNW TCEs by the reported method.

Non-enzymatic glucose sensor based on electrodeposited copper on carbon paste electrode (Cu/CPE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurani, Dita Arifa, E-mail: d.arifa@sci.ui.ac.id; Wibowo, Rahmat; Fajri, Iqbal Farhan El

The development of non-enzymatic glucose sensor has much attention due to their applications in glucose monitoring. In this research, copper oxide is used as a non-enzymatic glucose sensor by oxidizing glucose to gluconolactone. Copper was electrodeposited on Carbon paste electrode (CPE) at constant potential. The experimental condition was varied in electrodeposition of Cu with the following parameters: Electrodeposition time 60 s, 120 s and 180 s and potential reduction -0.166 V, -0.266 V and -0.366 V. The effective performance of these working electrodes in sensing glucose was investigated. The Cu/CPE which used -0.366 V potential reduction and 120 s electrodeposition time shows the bestmore » performance. The amperometric response current in concentration range 1.6-62.5 mM of glucose gives the good linearity R{sup 2} = 0.9988, low detection limit 0.6728 mM and high sensitivity 1183.59 µA mM{sup −1}cm{sup −2}. Furthermore this sensor exhibited a good repeatability with %RSD = 1.31% (n=10) and high stability with %RSD = 1.51% (n=5 days). The homogeneity of Cu particles on CPE was investigated by Scanning Electron Microscope (SEM).« less

High performance fuel electrodes fabricated by electroless plating of copper on BaZr0.8Ce0.1Y0.1O3-δ proton-conducting ceramic

NASA Astrophysics Data System (ADS)

Patki, Neil S.; Way, J. Douglas; Ricote, Sandrine

2017-10-01

The stability of copper at high temperatures in reducing and hydrocarbon-containing atmospheres makes it a good candidate for fabricating fuel electrodes on proton-conducting ceramics, such as BaZr0.9-xCexY0.1O3-δ (BZCY). In this work, the electrochemical performance of Cu-based electrodes fabricated by electroless plating (ELP) on BaZr0.8Ce0.1Y0.1O3-δ is studied with impedance spectroscopy. Three activation catalysts (Pd, Ru, and Cu) are investigated and ELP is compared to a commercial Cu paste (ESL 2312-G) for electrode fabrication. The area specific resistances (ASR) for Pd, Ru, and Cu activations at 700 °C in moist 5% H2 in Ar are 2.1, 3.2, and 13.4 Ω cm2, respectively. That is a 1-2 orders of magnitude improvement over the commercial Cu paste (192 Ω cm2). Furthermore, the ASR has contributions from electrode processes and charge transfer at the electrode/electrolyte interface. Additionally, the morphology of the as-fabricated electrode is unaffected by the activation catalyst. However, heat treatment at 750 °C in H2 for 24 h leads to sintering and large reorganization of the electrode fabricated with Cu activation (micron sized pores seen in the tested sample), while Pd and Ru activations are immune to such reorganization. Thus, Pd and Ru are identified as candidates for future work with improvements to charge transfer required for the former, and better electrode processes required for the latter.

Als1 and Als3 regulate the intracellular uptake of copper ions when Candida albicans biofilms are exposed to metallic copper surfaces.

PubMed

Zheng, Sha; Chang, Wenqiang; Li, Chen; Lou, Hongxiang

2016-05-01

Copper surfaces possess efficient antimicrobial effect. Here, we reported that copper surfaces could inactivate Candida albicans biofilms within 40 min. The intracellular reactive oxygen species in C. albicans biofilms were immediately stimulated during the contact of copper surfaces, which might be an important factor for killing the mature biofilms. Copper release assay demonstrated that the copper ions automatically released from the surface of 1 mm thick copper coupons with over 99.9% purity are not the key determinant for the copper-mediated killing action. The susceptibility test to copper surfaces by using C. albicans mutant strains, which were involved in efflux pumps, adhesins, biofilms formation or osmotic stress response showed that als1/als1 and als3/als3 displayed higher resistance to the copper surface contact than other mutants did. The intracellular concentration of copper ions was lower in als1/als1 and als3/als3 than that in wild-type strain. Transcriptional analysis revealed that the expression of copper transporter-related gene, CRP1, was significantly increased in als1/als1, als3/als3, suggesting a potential role of ALS1 and ALS3 in absorbing ions by regulating the expression of CRP1 This study provides a potential application in treating pathogenic fungi by using copper surfaces and uncovers the roles of ALS1 and ALS3 in absorbing copper ions for C. albicans. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Supercapacitors based on pillared graphene nanostructures.

PubMed

Lin, Jian; Zhong, Jiebin; Bao, Duoduo; Reiber-Kyle, Jennifer; Wang, Wei; Vullev, Valentine; Ozkan, Mihrimah; Ozkan, Cengiz S

2012-03-01

We describe the fabrication of highly conductive and large-area three dimensional pillared graphene nanostructure (PGN) films from assembly of vertically aligned CNT pillars on flexible copper foils for applications in electric double layer capacitors (EDLC). The PGN films synthesized via a one-step chemical vapor deposition process on flexible copper foils exhibit high conductivity with sheet resistance as low as 1.6 ohms per square and possessing high mechanical flexibility. Raman spectroscopy indicates the presence of multi walled carbon nanotubes (MWCNT) and their morphology can be controlled by the growth conditions. It was discovered that nitric acid treatment can significantly increase the specific capacitance of the devices. EDLC devices based on PGN electrodes (surface area of 565 m2/g) demonstrate enhanced performance with specific capacitance value as high as 330 F/g extracted from the current density-voltage (CV) measurements and energy density value of 45.8 Wh/kg. The hybrid graphene-CNT nanostructures are attractive for applications including supercapacitors, fuel cells and batteries.

Defining a Materials Database for the Design of Copper Binary Alloy Catalysts for Electrochemical CO2 Conversion.

PubMed

Lee, Chan Woo; Yang, Ki Dong; Nam, Dae-Hyun; Jang, Jun Ho; Cho, Nam Heon; Im, Sang Won; Nam, Ki Tae

2018-01-24

While Cu electrodes are a versatile material in the electrochemical production of desired hydrocarbon fuels, Cu binary alloy electrodes are recently proposed to further tune reaction directionality and, more importantly, overcome the intrinsic limitation of scaling relations. Despite encouraging empirical demonstrations of various Cu-based metal alloy systems, the underlying principles of their outstanding performance are not fully addressed. In particular, possible phase segregation with concurrent composition changes, which is widely observed in the field of metallurgy, is not at all considered. Moreover, surface-exposed metals can easily form oxide species, which is another pivotal factor that determines overall catalytic properties. Here, the understanding of Cu binary alloy catalysts for CO 2 reduction and recent progress in this field are discussed. From the viewpoint of the thermodynamic stability of the alloy system and elemental mixing, possible microstructures and naturally generated surface oxide species are proposed. These basic principles of material science can help to predict and understand metal alloy structure and, moreover, act as an inspiration for the development of new binary alloy catalysts to further improve CO 2 conversion and, ultimately, achieve a carbon-neutral cycle. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Porous metal-organic framework Cu3(BTC)2 as catalyst used in air-cathode for high performance of microbial fuel cell.

PubMed

Tian, Pei; Liu, Di; Li, Kexun; Yang, Tingting; Wang, Junjie; Liu, Yi; Zhang, Song

2017-11-01

Metal-organic framework Cu 3 (BTC) 2 , prepared by an easy hydrothermal method, was used as the oxygen-based catalyst in microbial fuel cell (MFC). The maximum power density of Cu 3 (BTC) 2 modified air-cathode MFC was 1772±15mWm -2 , almost 1.8 times higher than the control. BET results disclosed high specific surface area of 2159.7m 2 g -1 and abundant micropores structure. Regular octahedron and porous surface of Cu 3 (BTC) 2 were observed in SEM. XPS testified the existence of divalent copper in the extended 3D frameworks, which importantly acted as the Lewis-acid sites or redox centers in ORR. Additionally, the total resistance decreased by 42% from 17.60 to 10.24Ω compared with bare AC electrode. The rotating disk electrode test results showed a four-electron transfer pathway for Cu 3 (BTC) 2 , which was crucial for electrochemical catalytic activity. All the structural and electrochemical advantages make Cu 3 (BTC) 2 a promising catalyst for ORR in MFC. Copyright © 2017. Published by Elsevier Ltd.

Effects of momentum transfer on sizing of current collectors for lithium-ion batteries during laser cutting

NASA Astrophysics Data System (ADS)

Lee, Dongkyoung; Mazumder, Jyotirmoy

2018-02-01

One of the challenges of the lithium-ion battery manufacturing process is the sizing of electrodes with good cut surface quality. Poor cut surface quality results in internal short circuits in the cells and significant heat generation. One of the solutions that may improve the cut quality with a high cutting speed is laser cutting due to its high energy concentration, fast processing time, high precision, small heat affected zone, flexible range of laser power and contact free process. In order to utilize the advantages of laser electrode cutting, understanding the physical phenomena for each material is crucial. Thus, this study focuses on the laser cutting of current collectors, such as pure copper and aluminum. A 3D self-consistent mathematical model for the laser cutting, including fluid flow, heat transfer, recoil pressure, multiple reflections, capillary and thermo-capillary forces, and phase changes, is presented and solved numerically. Simulation results for the laser cutting are analyzed in terms of penetration time, depth, width, and absorptivity, based on these selected laser parameters. In addition, melt pool flow, melt pool geometry and temperature distribution are investigated.

Long-term stability of Cu surface nanotips

NASA Astrophysics Data System (ADS)

Jansson, V.; Baibuz, E.; Djurabekova, F.

2016-07-01

Sharp nanoscale tips on the metal surfaces of electrodes enhance locally applied electric fields. Strongly enhanced electric fields trigger electron field emission and atom evaporation from the apexes of nanotips. Together, these processes may explain electric discharges in the form of small local arcs observed near metal surfaces in the presence of electric fields, even in ultra-high vacuum conditions. In the present work, we investigate the stability of nanoscale tips by means of computer simulations of surface diffusion processes on copper, the main material used in high-voltage electronics. We study the stability and lifetime of thin copper (Cu) surface nanotips at different temperatures in terms of diffusion processes. For this purpose we have developed a surface kinetic Monte Carlo (KMC) model where the jump processes are described by tabulated precalculated energy barriers. We show that tall surface features with high aspect ratios can be fairly stable at room temperature. However, the stability was found to depend strongly on the temperature: 13 nm nanotips with the major axes in the < 110> crystallographic directions were found to flatten down to half of the original height in less than 100 ns at temperatures close to the melting point, whereas no significant change in the height of these nanotips was observed after 10 {{μ }}{{s}} at room temperature. Moreover, the nanotips built up along the < 110> crystallographic directions were found to be significantly more stable than those oriented in the < 100> or < 111> crystallographic directions. The proposed KMC model has been found to be well-suited for simulating atomic surface processes and was validated against molecular dynamics simulation results via the comparison of the flattening times obtained by both methods. We also note that the KMC simulations were two orders of magnitude computationally faster than the corresponding molecular dynamics calculations.

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)

Machining of AISI D2 Tool Steel with Multiple Hole Electrodes by EDM Process

NASA Astrophysics Data System (ADS)

Prasad Prathipati, R.; Devuri, Venkateswarlu; Cheepu, Muralimohan; Gudimetla, Kondaiah; Uzwal Kiran, R.

2018-03-01

In recent years, with the increasing of technology the demand for machining processes is increasing for the newly developed materials. The conventional machining processes are not adequate to meet the accuracy of the machining of these materials. The non-conventional machining processes of electrical discharge machining is one of the most efficient machining processes is being widely used to machining of high accuracy products of various industries. The optimum selection of process parameters is very important in machining processes as that of an electrical discharge machining as they determine surface quality and dimensional precision of the obtained parts, even though time consumption rate is higher for machining of large dimension features. In this work, D2 high carbon and chromium tool steel has been machined using electrical discharge machining with the multiple hole electrode technique. The D2 steel has several applications such as forming dies, extrusion dies and thread rolling. But the machining of this tool steel is very hard because of it shard alloyed elements of V, Cr and Mo which enhance its strength and wear properties. However, the machining is possible by using electrical discharge machining process and the present study implemented a new technique to reduce the machining time using a multiple hole copper electrode. In this technique, while machining with multiple holes electrode, fin like projections are obtained, which can be removed easily by chipping. Then the finishing is done by using solid electrode. The machining time is reduced to around 50% while using multiple hole electrode technique for electrical discharge machining.

A novel highly selective and sensitive detection of serotonin based on Ag/polypyrrole/Cu2O nanocomposite modified glassy carbon electrode.

PubMed

Selvarajan, S; Suganthi, A; Rajarajan, M

2018-06-01

A silver/polypyrrole/copper oxide (Ag/PPy/Cu 2 O) ternary nanocomposite was prepared by sonochemical and oxidative polymerization simple way, in which Cu 2 O was decorated with Ag nanoparticles, and covered by polyprrole (PPy) layer. The as prepared materials was characterized by UV-vis-spectroscopy (UV-vis), FT-IR, X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM) with EDX, high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Sensing of serotonin (5HT) was evaluated electrocatalyst using polypyrrole/glassy carbon electrode (PPy/GCE), polypyrrole/copper oxide/glassy carbon electrode (PPy/Cu 2 O/GCE) and silver/polypyrrole/copper oxide/glassy carbon electrode (Ag/PPy/Cu 2 O/GCE). The Ag/PPy/Cu 2 O/GCE was electrochemically treated in 0.1MPBS solution through cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The peak current response increases linearly with 5-HT concentration from 0.01 to 250 µmol L -1 and the detection limit was found to be 0.0124 μmol L -1 . It exhibits high electrocatalytic activity, satisfactory repeatability, stability, fast response and good selectivity against potentially interfering species, which suggests its potential in the development of sensitive, selective, easy-operation and low-cost serotonin sensor for practical routine analyses. The proposed method is potential to expand the possible applied range of the nanocomposite material for detection of various concerned electro active substances. Copyright © 2018 Elsevier B.V. All rights reserved.

Nanoscale Nucleation and Growth of Electrodeposited Lithium Metal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pei, Allen; Zheng, Guangyuan; Shi, Feifei

Lithium metal has re-emerged as an exciting anode for high energy lithium-ion batteries due to its high specific capacity of 3860 mAh g -1 and lowest electrochemical potential of all known materials. However, lithium has been plagued by the issues of dendrite formation, high chemical reactivity with electrolyte, and infinite relative volume expansion during plating and stripping, which present safety hazards and low cycling efficiency in batteries with lithium metal electrodes. There have been a lot of recent studies on Li metal although little work has focused on the initial nucleation and growth behavior of Li metal, neglecting a criticalmore » fundamental scientific foundation of Li plating. Here, we study experimentally the morphology of lithium in the early stages of nucleation and growth on planar copper electrodes in liquid organic electrolyte. We elucidate the dependence of lithium nuclei size, shape, and areal density on current rate, consistent with classical nucleation and growth theory. We found that the nuclei size is proportional to the inverse of overpotential and the number density of nuclei is proportional to the cubic power of overpotential. Finally, based on this understanding, we propose a strategy to increase the uniformity of electrodeposited lithium on the electrode surface.« less

Nanoscale Nucleation and Growth of Electrodeposited Lithium Metal

DOE PAGES

Pei, Allen; Zheng, Guangyuan; Shi, Feifei; ...

2017-01-10

Lithium metal has re-emerged as an exciting anode for high energy lithium-ion batteries due to its high specific capacity of 3860 mAh g -1 and lowest electrochemical potential of all known materials. However, lithium has been plagued by the issues of dendrite formation, high chemical reactivity with electrolyte, and infinite relative volume expansion during plating and stripping, which present safety hazards and low cycling efficiency in batteries with lithium metal electrodes. There have been a lot of recent studies on Li metal although little work has focused on the initial nucleation and growth behavior of Li metal, neglecting a criticalmore » fundamental scientific foundation of Li plating. Here, we study experimentally the morphology of lithium in the early stages of nucleation and growth on planar copper electrodes in liquid organic electrolyte. We elucidate the dependence of lithium nuclei size, shape, and areal density on current rate, consistent with classical nucleation and growth theory. We found that the nuclei size is proportional to the inverse of overpotential and the number density of nuclei is proportional to the cubic power of overpotential. Finally, based on this understanding, we propose a strategy to increase the uniformity of electrodeposited lithium on the electrode surface.« less

Nanoscale Nucleation and Growth of Electrodeposited Lithium Metal.

PubMed

Pei, Allen; Zheng, Guangyuan; Shi, Feifei; Li, Yuzhang; Cui, Yi

2017-02-08

Lithium metal has re-emerged as an exciting anode for high energy lithium-ion batteries due to its high specific capacity of 3860 mAh g -1 and lowest electrochemical potential of all known materials. However, lithium has been plagued by the issues of dendrite formation, high chemical reactivity with electrolyte, and infinite relative volume expansion during plating and stripping, which present safety hazards and low cycling efficiency in batteries with lithium metal electrodes. There have been a lot of recent studies on Li metal although little work has focused on the initial nucleation and growth behavior of Li metal, neglecting a critical fundamental scientific foundation of Li plating. Here, we study experimentally the morphology of lithium in the early stages of nucleation and growth on planar copper electrodes in liquid organic electrolyte. We elucidate the dependence of lithium nuclei size, shape, and areal density on current rate, consistent with classical nucleation and growth theory. We found that the nuclei size is proportional to the inverse of overpotential and the number density of nuclei is proportional to the cubic power of overpotential. Based on this understanding, we propose a strategy to increase the uniformity of electrodeposited lithium on the electrode surface.

Electrostatic interaction between an enzyme and electrodes in the electric double layer examined in a view of direct electron transfer-type bioelectrocatalysis.

PubMed

Sugimoto, Yu; Kitazumi, Yuki; Tsujimura, Seiya; Shirai, Osamu; Yamamoto, Masahiro; Kano, Kenji

2015-01-15

Effects of the electrode poential on the activity of an adsorbed enzyme has been examined by using copper efflux oxidase (CueO) as a model enzyme and by monitoring direct electron transfer (DET)-type bioelectrocatalysis of oxygen reduction. CueO adsorbed on bare Au electrodes at around the point of zero charge (E(pzc)) shows the highest DET activity, and the activity decreases as the adsorption potential (E(ad); at which the enzyme adsorbs) is far from E(pzc). We propose a model to explain the phenomena in which the electrostatic interaction between the enzyme and electrodes in the electric double layer affects the orientation and the stability of the adsorbed enzyme. The self-assembled monolayer of butanethiol on Au electrodes decreases the electric field in the outside of the inner Helmholtz plane and drastically diminishes the E(ad) dependence of the DET activity of CueO. When CueO is adsorbed on bare Au electrodes under open circuit potential and then is held at hold potentials (E(ho)) more positive than E(pzc), the DET activity of the CueO rapidly decreases with the hold time. The strong electric field with positive surface charge density on the metallic electrode (σ(M)) leads to fatal denaturation of the adsorbed CueO. Such denaturation effect is not so serious at E(ho)

Work function measurements of copper nanoparticle intercalated polyaniline nanocomposite thin films

NASA Astrophysics Data System (ADS)

Patil, U. V.; Ramgir, Niranjan S.; Bhogale, A.; Debnath, A. K.; Muthe, K. P.; Gadkari, S. C.; Kothari, D. C.

2017-05-01

The nature of contact between the electrode and the sensing material plays a crucial role in governing the sensing mechanism. Thin films of polyaniline (PANI) and copper-polyaniline nanocomposite (NC) have been deposited at room temperatures by in-situ oxidative polymerization of aniline in the presence of Cu nanoparticles. For sensing applications a thin film Au (gold) ˜100 nm is deposited and used as a conducting electrode. To understand the nature of contact (i.e., ohmic or Schottky) the work function of the conducting polyaniline and nanocomposite films were measured using Kelvin Probe method. I-V characteristics of PANI and NC films investigated at room temperatures further corroborates and confirms the formation of Ohmic contact as evident from work function measurements.

Control of the Helicity Content of a Gun-Generated Spheromak by Incorporating a Conducting Shell into a Magnetized Coaxial Plasma Gun

NASA Astrophysics Data System (ADS)

Matsumoto, Tadafumi; Sekiguchi, Jun'ichi; Asai, Tomohiko

In the formation of magnetized plasmoid by a magnetized coaxial plasma gun (MCPG), the magnetic helicity content of the generated plasmoid is one of the critical parameters. Typically, the bias coil to generate a poloidal flux is mounted either on the outer electrode or inside the inner electrode. However, most of the flux generated in the conventional method spreads even radially outside of the formation region. Thus, only a fraction of the total magnetic flux is actually exploited for helicity generation in the plasmoid. In the proposed system, the plasma gun incorporates a copper shell mounted on the outer electrode. By changing the rise time of the discharge bias coil current and the geometrical structure of the shell, the magnetic field structure and its time evolution can be controlled. The effect of the copper shell has been numerically simulated for the actual gun structure, and experimentally confirmed. This may increase the magnetic helicity content results, through increased poloidal magnetic field.

Improved lifetime high voltage switch electrode

NASA Astrophysics Data System (ADS)

Halverson, W.

1985-06-01

In this Phase 1 Small Business Innovation Research (SBIR) program, preliminary tests of ion implantation to increase the lifetime of spark switch electrodes have indicated that a 185 keV carbon ion implant into a tungsten-copper composite has reduced electrode erosion by a factor of two to four. Apparently, the thin layer of tungsten carbide (WC) has better thermal properties than pure tungsten; the WC may have penetrated into the unimplanted body of the electrode by liquid and/or solid phase diffusion during erosion testing. These encouraging results should provide the basis for a Phase 2 SBIR program to investigate further the physical and chemical effects of ion implantation on spark gap electrodes and to optimize the technique for applications.

Visibility and oxidation stability of hybrid-type copper mesh electrodes with combined nickel-carbon nanotube coating

NASA Astrophysics Data System (ADS)

Kim, Bu-Jong; Hwang, Young-Jin; Park, Jin-Seok

2017-04-01

Hybrid-type transparent conductive electrodes (TCEs) were fabricated by coating copper (Cu) meshes with carbon nanotube (CNT) via electrophoretic deposition, and with nickel (Ni) via electroplating. For the fabricated electrodes, the effects of the coating with CNT and Ni on their transmittance and reflectance in the visible-light range, electrical sheet resistance, and chromatic parameters (e.g., redness and yellowness) were characterized. Also, an oxidation stability test was performed by exposing the electrodes to air for 20 d at 85 °C and 85% temperature and humidity conditions, respectively. It was discovered that the CNT coating considerably reduced the reflectance of the Cu meshes, and that the Ni coating effectively protected the Cu meshes against oxidation. Furthermore, after the coating with CNT, both the redness and yellowness of the Cu mesh regardless of the Ni coating approached almost zero, indicating a natural color. The experiment results confirmed that the hybrid-type Cu meshes with combined Ni-CNT coating improved characteristics in terms of reflectance, sheet resistance, oxidation stability, and color, superior to those of the primitive Cu mesh, and also simultaneously satisfied most of the requirements for TCEs.

Fabrication of high wettability gradient on copper substrate

NASA Astrophysics Data System (ADS)

Huang, Ding-Jun; Leu, Tzong-Shyng

2013-09-01

Copper is one of the most widely used materials in condensation heat transfer. Recently there has been great interest in improving the condensation heat transfer efficiency through copper surface modification. In this study, we describe the fabrication processes of how copper surfaces were modified to be superhydrophilic (CA ≤ 10°) and superhydrophobic (CA > 150°) by means of H2O2 immersion and fluorination with Teflon. The wettability gradient of copper surfaces with contact angles (CA) changing from superhydrophilic to superhydrophobic are also demonstrated. Unlike previous studies on gradient surfaces in which the wettability gradient is controlled either non-precisely or entirely uncontrolled, in this study, the contact angles along wettability gradient copper surfaces vary with a precisely designed gradient. It is demonstrated that a high wettability gradient copper surface can be successfully fabricated using photolithography to define the area ratios between superhydrophilic and superhydrophobic patterns within a short distance. The fabricated wettability gradient of copper surfaces is expected to be able to enhance the condensation heat transfer efficiency.

Rigid particulate matter sensor

DOEpatents

Hall, Matthew [Austin, TX

2011-02-22

A sensor to detect particulate matter. The sensor includes a first rigid tube, a second rigid tube, a detection surface electrode, and a bias surface electrode. The second rigid tube is mounted substantially parallel to the first rigid tube. The detection surface electrode is disposed on an outer surface of the first rigid tube. The detection surface electrode is disposed to face the second rigid tube. The bias surface electrode is disposed on an outer surface of the second rigid tube. The bias surface electrode is disposed to face the detection surface electrode on the first rigid tube. An air gap exists between the detection surface electrode and the bias surface electrode to allow particulate matter within an exhaust stream to flow between the detection and bias surface electrodes.

Copper foils with gradient structure in thickness direction and different roughnesses on two surfaces fabricated by double rolling

NASA Astrophysics Data System (ADS)

Wang, Xi-yong; Liu, Xue-feng; Zou, Wen-jiang; Xie, Jian-xin

2013-12-01

Copper foils with gradient structure in thickness direction and different roughnesses on two surfaces were fabricated by double rolling. The two surface morphologies of double-rolled copper foils are quite different, and the surface roughness values are 61 and 1095 nm, respectively. The roughness value of matt surface can meet the requirement for bonding the resin matrix with copper foils used for flexible printed circuit boards, thus may omit traditional roughening treatment; the microstructure of double-rolled copper foils demonstrates an obviously asymmetric gradient feature. From bright surface to matt surface in thickness direction, the average grain size first increases from 2.3 to 7.4 μm and then decreases to 3.6 μm; compared with conventional rolled copper foils, the double-rolled copper foils exhibit a remarkably increased bending fatigue life, and the increased range is about 16.2%.

Auger electron spectroscopy study of surface segregation in the binary alloys copper-1 atomic percent indium, copper-2 atomic percent tin, and iron-6.55 atomic percent silicon

NASA Technical Reports Server (NTRS)

Ferrante, J.

1973-01-01

Auger electron spectroscopy was used to examine surface segregation in the binary alloys copper-1 at. % indium, copper-2 at. % tin and iron-6.55 at. % silicon. The copper-tin and copper-indium alloys were single crystals oriented with the /111/ direction normal to the surface. An iron-6.5 at. % silicon alloy was studied (a single crystal oriented in the /100/ direction for study of a (100) surface). It was found that surface segregation occurred following sputtering in all cases. Only the iron-silicon single crystal alloy exhibited equilibrium segregation (i.e., reversibility of surface concentration with temperature) for which at present we have no explanation. McLean's analysis for equilibrium segregation at grain boundaries did not apply to the present results, despite the successful application to dilute copper-aluminum alloys. The relation of solute atomic size and solubility to surface segregation is discussed. Estimates of the depth of segregation in the copper-tin alloy indicate that it is of the order of a monolayer surface film.

Superstable transparent conductive Cu@Cu4Ni nanowire elastomer composites against oxidation, bending, stretching, and twisting for flexible and stretchable optoelectronics.

PubMed

Song, Jizhong; Li, Jianhai; Xu, Jiayue; Zeng, Haibo

2014-11-12

Low cost and high conductivity make copper (Cu) nanowire (NW) electrodes an attractive material to construct flexible and stretchable electronic skins, displays, organic light-emitting diodes (OLEDs), solar cells, and electrochromic windows. However, the vulnerabilities that Cu NW electrodes have to oxidation, bending, and stretching still present great challenges. This work demonstrates a new Cu@Cu4Ni NW conductive elastomer composite with ultrahigh stability for the first time. Cu@Cu4Ni NWs, facilely synthesized through a one-pot method, have highly crystalline alloyed shells, clear and abrupt interfaces, lengths more than 50 μm, and smooth surfaces. These virtues provide the NW-elastomer composites with a low resistance of 62.4 ohm/sq at 80% transparency, which is even better than the commercial ITO/PET flexible electrodes. In addition, the fluctuation amplitude of resistance is within 2 ohm/sq within 30 days, meaning that at ΔR/R0 = 1, the actual lifetime is estimated to be more than 1200 days. Neither the conductivity nor the performances of OLED with elastomers as conductive circuits show evident degradation during 600 cycles of bending, stretching, and twisting tests. These high-performance and extremely stable NW elastomeric electrodes could endow great chances for transparent, flexible, stretchable, and wearable electronic and optoelectronic devices.

Amperometric immunosensor for α-fetoprotein antigen in human serum based on co-immobilizing dinuclear copper complex and gold nanoparticle doped chitosan film

NASA Astrophysics Data System (ADS)

Gan, Ning; Meng, Ling Hua; Wang, Feng

2009-09-01

A sensitive amperometric immunosensor for α-fetoprotein (AFP), a tumor marker for the diagnosis of hepatocellular carcinoma (HCC), was constructed, The immunosensor is prepared by co-immobilizing [Cu2(phen)2Cl2] (μ-Cl)2 (CuL), nano-Au/Chitosan(Chit) composite, horseradish peroxidase (HRP) and AFP antibody(anti-AFP) on a glassy carbon electrode (GCE). Firstly, CuL was irreversibly absorb on GCE electrode through π-π stacking interaction; then nano-Au/Chit composite was immobilized onto the electrode because of its excellent membrane-forming ability, finally HRP and anti-AFP was adsorbed onto the surface of the gold nanoparticles to construct GCE | CuL/nanoAu-chit/HRP/anti-AFP immunosensor. The preparation procedure of the electrode was characterized by electrochemical and spectroscopy method. The results showed that this immunosensor exhibited an excellent electrocatalytic response to the reduction of hydrogen peroxide (H2O2) without the aid of an electron mediator, offers a high-sensitivity (1710 nA · ng-1 · ml-1) for the detection of AFP and has good correlation for detection of AFP in the range of 0.2 to 120.0 ng/ml with a detection limit of 0.05 ng/ml. The biosensor showed high selectivity as well as good stability and reproductivity.

Direct evidence of void passivation in Cu(InGa)(SSe){sub 2} absorber layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Dongho; Kim, Young-Su; Mo, Chan B.

We have investigated the charge collection condition around voids in copper indium gallium sulfur selenide (CIGSSe) solar cells fabricated by sputter and a sequential process of selenization/sulfurization. In this study, we found direct evidence of void passivation by using the junction electron beam induced current method, transmission electron microscopy, and energy dispersive X-ray spectroscopy. The high sulfur concentration at the void surface plays an important role in the performance enhancement of the device. The recombination around voids is effectively suppressed by field-assisted void passivation. Hence, the generated carriers are easily collected by the electrodes. Therefore, when the S/(S + Se)more » ratio at the void surface is over 8% at room temperature, the device performance degradation caused by the recombination at the voids is negligible at the CIGSSe layer.« less

Depth profile composition studies of thin film CdS:Cu2S solar cells using XPS and AES

NASA Astrophysics Data System (ADS)

Bhide, V. G.; Salkalachen, S.; Rastogi, A. C.; Rao, C. N. R.; Hegde, M. S.

1981-09-01

Studies of the surface composition and depth profiles of thin film CdS:Cu2S solar cells based on the techniques of X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) are reported. Specimens were fabricated by the thermal deposition of polycrystalline CdS films onto silver-backed electrodes predeposited on window glass substrates, followed by texturization in hot HCl and chemical plating in a hot CuCl(I) bath for a few seconds to achieve the topotaxial growth of CuS films. The XPS and AES studies indicate the junction to be fairly diffused in the as-prepared cell, with heat treatment in air at 210 C sharpening the junction, improving the stoichiometry of the Cu2S layer and thus improving cell performance. The top copper sulfide layer is found to contain impurities such as Cd, Cl, O and C, which may be removed by mild Ar(+) ion beam etching. The presence of copper deep in the junction is invariably detected, apparently in the grain boundary region in the form of CuS or Cu(2+) trapped in the lattice. It is also noted that the nominal valence state of copper changes abruptly from Cu(+) to Cu(2+) across the junction.

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.

Dielectric elastomers with novel highly-conducting electrodes

NASA Astrophysics Data System (ADS)

Böse, Holger; Uhl, Detlev

2013-04-01

Beside the characteristics of the elastomer material itself, the performance of dielectric elastomers in actuator, sensor as well as generator applications depends also on the properties of the electrode material. Various electrode materials based on metallic particles dispersed in a silicone matrix were manufactured and investigated. Anisotropic particles such as silver-coated copper flakes and silver-coated glass flakes were used for the preparation of the electrodes. The concentration of the metallic particles and the thickness of the electrode layers were varied. Specific conductivities derived from resistance measurements reached about 100 S/cm and surmount those of the reference materials based on graphite and carbon black by up to three orders of magnitude. The high conductivities of the new electrode materials can be maintained even at very large stretch deformations up to 200 %.

Metallic copper corrosion rates, moisture content, and growth medium influence survival of copper-ion resistant bacteria

PubMed Central

Elguindi, Jutta; Moffitt, Stuart; Hasman, Henrik; Andrade, Cassandra; Raghavan, Srini; Rensing, Christopher

2013-01-01

The rapid killing of various bacteria in contact with metallic copper is thought to be influenced by influx of copper ions into the cells but the exact mechanism is not fully understood. This study showed that the kinetics of contact-killing of copper surfaces depended greatly on the amount of moisture present, copper content of alloys, type of medium used, and type of bacteria. We examined antibiotic- and copper-ion resistant strains of Escherichia coli and Enterococcus faecium isolated from pig farms following the use of copper sulfate as feed supplement. The results showed rapid killing of both copper-ion resistant E. coli and E. faecium strains when samples in rich medium were spread in a thin, moist layer on copper alloys with 85% or greater copper content. E. coli strains were rapidly killed under dry conditions while E. faecium strains were less affected. Electroplated copper surface corrosion rates were determined from electro-chemical polarization tests using the Stern-Geary method and revealed decreased corrosion rates with benzotriazole and thermal oxide coating. Copper-ion resistant E. coli and E. faecium cells suspended in 0.8% NaCl showed prolonged survival rates on electroplated copper surfaces with benzotriazole coating and thermal oxide coating compared to surfaces without anti-corrosion treatment. Control of surface corrosion affected the level of copper ion influx into bacterial cells which contributed directly to bacterial killing. PMID:21085951

In-vitro evaluation of copper nanoparticles cytotoxicity on prostate cancer cell lines and their antioxidant, sensing and catalytic activity: One-pot green approach.

PubMed

Prasad, P Reddy; Kanchi, S; Naidoo, E B

2016-08-01

In this study, Broccoli green extract was reported as a green and environmental friendly precursor for the one-pot biosynthesis of copper nanoparticles. The synthesized nanoparticles were characterized by UV-vis, FTIR, TEM, DLS, XRD and cyclic voltammetry. The TEM and DLS results showed that the NPs are in spherical and monodispersed with an average particle size of ~4.8nm. The FTIR results confirmed the occurrence of bioactive functional groups that are responsible for reducing cupric sulphate to copper ions. The UV-vis spectrophotometry was used for catalytic reduction of 4-nitrophenol and its dynamic reaction in Britton-Robinson buffer solution. This catalytic activity was further supported with methylene blue and methyl red dyes degradation. The nanocatalyst can be recovered from the reaction mixture and reused many times with none vital loss of catalytic activity. The Broccoli green extract modified copper nanoparticles coated on screen printing electrode laid a new sensing platform and has an excellent electrocatalytic activity. Furthermore, surface modified CuNPs with Broccoli green extract exhibited no cytotoxicity at the concentration ranging from 0.5 to 1.5μM on the prostate cancer (PC-3) cell lines. The maximum scavenging % of Broccoli green extract modified CuNPs was found to be >70.50% at the concentration of 0.25mM against 1,1-diphenyl-2-picrylhydrazyl. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrochemically protected copper(I)-catalyzed azide-alkyne cycloaddition.

PubMed

Hong, Vu; Udit, Andrew K; Evans, Richard A; Finn, M G

2008-06-16

The copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has found broad application in myriad fields. For the most demanding applications that require high yields at low substrate concentrations, highly active but air-sensitive copper complexes must be used. We describe here the use of an electrochemical potential to maintain catalysts in the active Cu(I) oxidation state in the presence of air. This simple procedure efficiently achieves excellent yields of CuAAC products from both small-molecule and protein substrates without the use of potentially damaging chemical reducing agents. A new water-soluble carboxylated version of the popular tris(benzyltriazolylmethyl)amine (TBTA) ligand is also described. Cyclic voltammetry revealed reversible or quasi-reversible electrochemical redox behavior of copper complexes of the TBTA derivative (2; E(1/2)=60 mV vs. Ag/AgCl), sulfonated bathophenanthroline (3; E(1/2)=-60 mV), and sulfonated tris(benzimidazoylmethyl)amine (4; E(1/2) approximately -70 mV), and showed catalytic turnover to be rapid relative to the voltammetry time scale. Under the influence of a -200 mV potential that was established by using a reticulated vitreous carbon working electrode, CuSO4 and 3 formed a superior catalyst. Electrochemically protected bioconjugations in air were performed by using bacteriophage Qbeta that was derivatized with azide moieties at surface lysine residues. Complete derivatization of more than 600 reactive sites per particle was demonstrated within 12 h of electrolysis with substoichiometric quantities of Cu3.

Effect of O2, N2 and H2 on annealing of pad printed high conductive Ag-Cu nano-alloy electrodes

NASA Astrophysics Data System (ADS)

Manjunath, G.; Anusha, P.; Salian, Ashritha; Gupta, Bikesh; Mandal, Saumen

2018-01-01

In this study, annealing of pad printed Ag-Cu based conducting ink was studied in oxidizing, inert and reducing atmosphere to verify its oxidation dependent conductivity. Ag-Cu manually was formulated adopting polyol method; where silver nitrate and copper nitrate serve as initial metal precursors. Polyvinylpyrrolidone (PVP), ethylene glycol and sodium borohydride act as a stabilizer, solvent and reducing agent respectively. The nanoalloys were with an average particle size ˜48 ± 15 nm, capped with polyvinylpyrrolidone to avoid agglomeration and stable in non-polar solvents. Formation of nanoalloy, Ag 90 wt%-Cu 10 wt%, was verified through a peak shift in UV-visible spectroscopy, found at 470 nm along with Nelson-Relay curve fitting and x-ray photoelectron spectroscopy study. The calculated lattice parameter of nanoalloy ˜4.034 Å, was in between pure silver and copper. The crystallite size was calculated using Debye-Scherrer, Williamson-Hall isotropic strain model and Halder-Wagner method. Electrode patterns were printed on a glass substrate by pad printing and were annealed under O2, N2 and H2 atmosphere to study the oxidation kinetics of copper. A maximum conductivity of -6.6 × 105 S m-1 was observed in inert atmosphere annealing as the conductivity is solely depends on the oxidation of copper; appears with uttermost Cu0 and least Cu2+ in x-ray photoelectron spectroscopy. High conductive space required between manually and dispersion ink can have a potential application as an electrode in printed electronics. Further refinement of size of the nanopaticles by polyol method could help to obtain the effect of quantum confinement.

Fabrication of mesoporous iron (Fe) doped copper sulfide (CuS) nanocomposite in the presence of a cationic surfactant via mild hydrothermal method for supercapacitors

NASA Astrophysics Data System (ADS)

Brown, J. William; Ramesh, P. S.; Geetha, D.

2018-02-01

We report fabrication of mesoporous Fe doped CuS nanocomposites with uniform mesoporous spherical structures via a mild hydrothermal method employing copper nitrate trihydrate (Cu (NO3).3H2O), Thiourea (Tu,Sc(NH2)2 and Iron tri nitrate (Fe(No3)3) as initial materials with cationic surfactant cetyltrimethylamoniame bromide (CTAB) as stabilizer/size controller and Ethylene glycol as solvent at 130 °C temperature. The products were characterized by XRD, SEM/EDX, TEM, FTIR and UV analysis. X-ray diffraction (XRD) spectra confirmed the Fe doped CuS nanocomposites which are crystalline in nature. EDX and XRD pattern confirmed that the product is hexagonal CuS phase. Fe doped spherical structure of CuS with grain size of 21 nm was confirmed by XRD pattern. Fe doping was identified by energy dispersive spectrometry (EDS). The Fourier-transform infrared (FTIR) spectroscopy results revealed the occurrence of active functional groups required for the reduction of copper ions. Studies showed that after a definite time relining on the chosen copper source, the obtained Fe-CuS nanocomposite shows a tendency towards self-assembly and creating mesoporous like nano and submicro structures by TEM/SAED. The achievable mechanism of producing this nanocomposite was primarily discussed. The electrochemical study confirms the pseudocapacitive nature of the CuS and Fe-CuS electrodes. The CuS and Fe-CuS electrode shows a specific capacitance of about 328.26 and 516.39 Fg-1 at a scan rate of 5 mVs-1. As the electrode in a supercapacitor, the mesoporous nanostructured Fe-CuS shows excellent capacitance characteristics.

Nanostructured copper phthalocyanine-sensitized multiwall carbon nanotube films.

PubMed

Hatton, Ross A; Blanchard, Nicholas P; Stolojan, Vlad; Miller, Anthony J; Silva, S Ravi P

2007-05-22

We report a detailed study of the interaction between surface-oxidized multiwall carbon nanotubes (o-MWCNTs) and the molecular semiconductor tetrasulfonate copper phthalocyanine (TS-CuPc). Concentrated dispersions of o-MWCNT in aqueous solutions of TS-CuPc are stable toward nanotube flocculation and exhibit spontaneous nanostructuring upon rapid drying. In addition to hydrogen-bonding interactions, the compatibility between the two components is shown to result from a ground-state charge-transfer interaction with partial charge transfer from o-MWCNT to TS-CuPc molecules orientated such that the plane of the macrocycle is parallel to the nanotube surface. The electronegativity of TS-CuPc as compared to unsubsubtituted copper phthalocyanine is shown to result from the electron-withdrawing character of the sulfonate substituents, which increase the molecular ionization potential and promote cofacial molecular aggregation upon drying. Upon spin casting to form uniform thin films, the experimental evidence is consistent with an o-MWCNT scaffold decorated with phthalocyanine molecules self-assembled into extended aggregates reminiscent of 1-D linearly stacked phthalocyanine polymers. Remarkably, this self-organization occurs in a fraction of a second during the spin-coating process. To demonstrate the potential utility of this hybrid material, it is successfully incorporated into a model organic photovoltaic cell at the interface between a poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester bulk heterojunction layer and an indium-tin oxide-coated glass electrode to increase the light-harvesting capability of the device and facilitate hole extraction. The resulting enhancement in power conversion efficiency is rationalized in terms of the electronic, optical, and morphological properties of the nanostructured thin film.

Electrochemical and thermal studies of lithium ion batteries

NASA Astrophysics Data System (ADS)

Lu, Wenquan

The structural, electrochemical, and thermal characteristics of carbonaceous anodes and LiNi0.8Co0.2O2 cathode in Li-ion cells were investigated using various electrochemical and calorimetric techniques. The electrode-electrolyte interface was investigated for various carbonaceous materials such as graphite with different shapes, surface modified graphite with copper, and novel carbon material derived from sepiolite template. The structural and morphological properties were determined using XRD, TGA, SEM, BET techniques. The electrochemical characteristics were studied using conventional electrochemical techniques such as galvanostatic charge/discharge cycling, cyclic voltammetry, and impedance (AC and DC) methods. It was observed that the electrochemical active surface area instead of the BET area plays a critical role in the irreversible capacity loss associated with the carbonaceous anodes. It was also found that the exfoliation of carbon anodes especially in PC based electrolyte could be significantly reduced by protective copper coating of the natural graphite. LiNi0.8Co0.2O2 cathode material was found to possess high energy density and excellent cycling characteristics. The structural and electrochemical properties of LiNi0.8Co 0.2O2 synthesized by sol-gel and solid-state methods were studied. Results of the AC impedance spectroscopy carried out on LiNi 0.8Co0.2O2 cathodes revealed that the charge transfer resistance is a function of the state of charge. The solid state Li + diffusion was calculated to be around 10-13 cm2/s in the oxide particle by Warburg impedance method. In addition, the cell fabricated with LiNi0.8Co0.2O 2 cathode showed excellent energy and power performance under static and dynamic load conditions that prevail in Electric and Hybrid Vehicles. Thermal properties of the LiNi0.8Co0.2O2 cathode, carbonaceous anodes, and Li-ion cells fabricated with these electrodes were also investigated using isothermal microcalorimetry (IMC), differential scanning calorimetry (DSC) and accelerated rate calorimetry (ARC). Isothermal micro-calorimeter was used to investigate the thermal behavior of the Li-ion cell and its electrodes. The overall heat changes during charge-discharge processes were explained in terms of the irreversible (resistive) and reversible (entropic) heats. It was observed that the reversible heat strongly depends on the structural or phase change occurring in the electrodes during Li-ion insertion and extraction reactions. It was also found that the contribution of the reversible heat to the overall cell heat generation rate was significant only at low cycling rates.

Orienting the Microstructure Evolution of Copper Phthalocyanine as an Anode Interlayer in Inverted Polymer Solar Cells for High Performance.

PubMed

Li, Zhiqi; Liu, Chunyu; Zhang, Xinyuan; Li, Shujun; Zhang, Xulin; Guo, Jiaxin; Guo, Wenbin; Zhang, Liu; Ruan, Shengping

2017-09-20

Recent advances in the interfacial modification of inverted-type polymer solar cells (PSCs) have resulted from controlling the surface energy of the cathode-modified layer (TiO 2 or ZnO) to enhance the short-circuit current (J sc ) or optimizing the contact morphology of the cathode (indium tin oxide or fluorine-doped tin oxide) and active layer to increase the fill factor. Herein, we report that the performance enhancement of PSCs is achieved by incorporating a donor macromolecule copper phthalocyanine (CuPc) as an anode modification layer. Using the approach based on orienting the microstructure evolution, uniformly dispersed island-shaped CuPc spot accumulations are built on the top of PTB7:PC 71 BM blend film, leading to an efficient spectral absorption and photogenerated exciton splitting. The best power conversion efficiency of PSCs is increased up to 9.726%. In addition to the enhanced light absorption, the tailored anode energy level alignment and optimized boundary morphology by incorporating the CuPc interlayer boost charge extraction efficiency and suppress the interfacial molecular recombination. These results demonstrate that surface morphology induction through molecular deposition is an effective method to improve the performance of PSCs, which reveals the potential implications of the interlayer between the organic active layer and the electrode buffer layer.

Instrumentation for in situ flow electrochemical Scanning Transmission X-ray Microscopy (STXM)

NASA Astrophysics Data System (ADS)

Prabu, Vinod; Obst, Martin; Hosseinkhannazer, Hooman; Reynolds, Matthew; Rosendahl, Scott; Wang, Jian; Hitchcock, Adam P.

2018-06-01

We report the design and performance of a 3-electrode device for real time in situ scanning transmission X-ray microscopy studies of electrochemical processes under both static (sealed, non-flow) conditions and with a continuous flow of electrolytes. The device was made using a combination of silicon microfabrication and 3D printing technologies. The performance is illustrated by results of a study of copper deposition and stripping at a gold working electrode. X-ray absorption spectromicroscopy at the Cu 2p edge was used to follow the evolution as a function of potential and time of the spatial distributions of Cu(0) and Cu(i) species electro-deposited from an aqueous solution of copper sulphate. The results are interpreted in terms of competing mechanisms for the reduction of Cu(ii).

Lid heater for glass melter

DOEpatents

Phillips, Terrance D.

1993-01-01

A glass melter having a lid electrode for heating the glass melt radiantly. The electrode comprises a series of INCONEL 690 tubes running above the melt across the melter interior and through the melter walls and having nickel cores inside the tubes beginning where the tubes leave the melter interior and nickel connectors to connect the tubes electrically in series. An applied voltage causes the tubes to generate heat of electrical resistance for melting frit injected onto the melt. The cores limit heat generated as the current passes through the walls of the melter. Nickel bus connection to the electrical power supply minimizes heat transfer away from the melter that would occur if standard copper or water-cooled copper connections were used between the supply and the INCONEL 690 heating tubes.

Lid heater for glass melter

DOEpatents

Phillips, T.D.

1993-12-14

A glass melter having a lid electrode for heating the glass melt radiantly. The electrode comprises a series of INCONEL 690 tubes running above the melt across the melter interior and through the melter walls and having nickel cores inside the tubes beginning where the tubes leave the melter interior and nickel connectors to connect the tubes electrically in series. An applied voltage causes the tubes to generate heat of electrical resistance for melting frit injected onto the melt. The cores limit heat generated as the current passes through the walls of the melter. Nickel bus connection to the electrical power supply minimizes heat transfer away from the melter that would occur if standard copper or water-cooled copper connections were used between the supply and the INCONEL 690 heating tubes. 3 figures.

Enhanced amperometric detection of metronidazole in drug formulations and urine samples based on chitosan protected tetrasulfonated copper phthalocyanine thin-film modified glassy carbon electrode.

PubMed

Meenakshi, S; Pandian, K; Jayakumari, L S; Inbasekaran, S

2016-02-01

An enhanced electrocatalytic reduction of metronidazole antibiotic drug molecule using chitosan protected tetrasulfonated copper phthalocyanine (Chit/CuTsPc) thin-film modified glassy carbon electrode (GCE) has been developed. An irreversible reduction occurs at -0.47V (vs. Ag/AgCl) using Chit/CuTsPc modified GCE. A maximum peak current value is obtained at pH1 and the electrochemical reduction reaction is a diffusion controlled one. The detection limit is found to be 0.41nM from differential pulse voltammetry (DPV) method. This present investigation method is adopted for electrochemical detection of metronidazole in drug formulation and urine samples by using DPV method. Copyright © 2015 Elsevier B.V. All rights reserved.

Printed Nano Cu and NiSi Contacts and Metallization for Solar Cell Modules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carmody, Michael John

There has long been a desire to replace the front-side silver contacts in silicon solar cells. There are two driving forces to do this. First, silver is an expensive precious metal. Secondly, the process to use silver requires that it be formulated into screen print pastes that need a lead-containing glass frit, and the use of lead is forbidden in many parts of the world. Because of the difficulty in replacing these pastes and the attendant processes, lead exemptions have granted to solar cells. Copper has been the replacement metal of choice because it is significantly cheaper than silver andmore » is very close to silver in electrical conductivity. Using processes which do not use lead, obviates it as an environmental contaminant. However, copper cannot be in contact with the silicon of the cell since it migrates through the silicon and causes defects which severely damage the efficiency of the cell. Hence, a conductive barrier must be placed between the copper and silicon and nickel, and especially nickel silicide, have been shown to be materials of choice. However, nickel must be sputtered and annealed to create the nickel silicide barrier, and copper has either been sputtered or plated. All of these processes require expensive, specialized equipment and plating uses environmentally unfriendly chemicals. Therefore, Intrinsiq proposed using printed nano nickel silicide ink (which we had previously invented) and printed nano copper ink to create these electrodes and barriers. We found that nano copper ink could be readily printed and sintered under a reducing atmosphere to give highly conductive grids. We further showed that nano nickel silicide ink could be readily jetted into grids on top of the silicon cell. It could then be annealed to create a barrier. However, it was found that the combination of printed NiSi and printed Cu did not give contact resistivity good enough to produce efficient cells. Only plated copper on top of the printed NiSi gave useful contact resistivity, and that proved to five to ten times less conductive than the commercial silver grids. Even so, the NiSi layer was a very good barrier to copper migration, even under harsh environmental conditions. Additionally, both plated copper and printed copper could be soldered to. While it may be possible to produce an all printed copper/nickel silicide top electrode for silicon cells, it was not easily demonstrated within the time and monetary constraints of the present project. Additionally, potential customers have told us that having to laser ablate the anti-reflection coating of cells to create a connection for NiSi, and the addition of two printing and annealing (sintering for copper) steps, adds too much expense to compensate for any potential cost savings from using copper. The cost benefits of copper have been further eroded by the facts that over the lifetime of this project, the cost of silver electrodes decreased due to manufacturers finding ways to use less and less silver, and inventing pastes which use less costly silver materials to begin with. All of these factors were considered and led to the decision to stop the program before actual manufacturing scale was attempted.« less

Surface functionalization of copper via oxidative graft polymerization of 2,2'-bithiophene and immobilization of silver nanoparticles for combating biocorrosion.

PubMed

Wan, Dong; Yuan, Shaojun; Neoh, K G; Kang, E T

2010-06-01

An environmentally benign approach to surface modification was developed to impart copper surface with enhanced resistance to corrosion, bacterial adhesion and biocorrosion. Oxidative graft polymerization of 2,2'-bithiophene from the copper surface with self-assembled 2,2'-bithiophene monolayer, and subsequent reduction of silver ions to silver nanoparticles (Ag NPs) on the surface, give rise to a homogeneous bithiophene polymer (PBT) film with densely coupled Ag NPs on the copper surface (Cu-g-PBT-Ag NP surface). The immobilized Ag NPs were found to significantly inhibit bacterial adhesion and enhance the antibacterial properties of the PBT modified copper surface. The corrosion inhibition performance of the functionalized copper substrates was evaluated by Tafel polarization curves and electrochemical impedance spectroscopy. Arising from the chemical affinity of thiols for the noble and coinage metals, the copper surface functionalized with both PBT brushes and Ag NPs also exhibits long-term stability, and is thus potentially useful for combating the combined problems of corrosion and biocorrosion in harsh marine and aquatic environments.

Polyethylene oxide film coating enhances lithium cycling efficiency of an anode-free lithium-metal battery.

PubMed

Assegie, Addisu Alemayehu; Cheng, Ju-Hsiang; Kuo, Li-Ming; Su, Wei-Nien; Hwang, Bing-Joe

2018-03-29

The practical implementation of an anode-free lithium-metal battery with promising high capacity is hampered by dendrite formation and low coulombic efficiency. Most notably, these challenges stem from non-uniform lithium plating and unstable SEI layer formation on the bare copper electrode. Herein, we revealed the homogeneous deposition of lithium and effective suppression of dendrite formation using a copper electrode coated with a polyethylene oxide (PEO) film in an electrolyte comprising 1 M LiTFSI, DME/DOL (1/1, v/v) and 2 wt% LiNO3. More importantly, the PEO film coating promoted the formation of a thin and robust SEI layer film by hosting lithium and regulating the inevitable reaction of lithium with the electrolyte. The modified electrode exhibited stable cycling of lithium with an average coulombic efficiency of ∼100% over 200 cycles and low voltage hysteresis (∼30 mV) at a current density of 0.5 mA cm-2. Moreover, we tested the anode-free battery experimentally by integrating it with an LiFePO4 cathode into a full-cell configuration (Cu@PEO/LiFePO4). The new cell demonstrated stable cycling with an average coulombic efficiency of 98.6% and capacity retention of 30% in the 200th cycle at a rate of 0.2C. These impressive enhancements in cycle life and capacity retention result from the synergy of the PEO film coating, high electrode-electrolyte interface compatibility, stable polar oligomer formation from the reduction of 1,3-dioxolane and the generation of SEI-stabilizing nitrite and nitride upon lithium nitrate reduction. Our result opens up a new route to realize anode-free batteries by modifying the copper anode with PEO to achieve ever more demanding yet safe interfacial chemistry and control of dendrite formation.

Evaluation of biocidal efficacy of copper alloy coatings in comparison with solid metal surfaces: generation of organic copper phosphate nanoflowers.

PubMed

Gutierrez, H; Portman, T; Pershin, V; Ringuette, M

2013-03-01

To analyse the biocidal efficacy of thermal sprayed copper surfaces. Copper alloy sheet metals containing >60% copper have been shown to exhibit potent biocidal activity. Surface biocidal activity was assessed by epifluorescence microscopy. After 2-h exposure at 20 °C in phosphate-buffered saline (PBS), contact killing of Gram-negative Escherichia coli and Gram-positive Staphylococcus epidermidis by brass sheet metal and phosphor bronze was 3-4-times higher than that by stainless steel. SEM observations revealed that the surface membranes of both bacterial strains were slightly more irregular when exposed to brass sheet metal than stainless steel. However, when exposed to phosphor bronze coating, E. coli were 3-4 times larger with irregular membrane morphology. In addition, the majority of the cells were associated with spherical carbon-copper-phosphate crystalline nanostructures characteristic of nanoflowers. The membranes of many of the S. epidermidis exhibited blebbing, and a small subset was also associated with nanoflowers. Our data indicate that increasing the surface roughness of copper alloys had a pronounced impact on the membrane integrity of Gram-positive and, to a lesser degree, Gram-negative bacteria. In the presence of PBS, carbon-copper-phosphate-containing nanoflowers were formed, likely nucleated by components derived from killed bacteria. The intimate association of the bacteria with the nanoflowers and phosphor bronze coating likely contributed to their nonreversible adhesion. Thermal spraying of copper alloys provides a strategy for the rapid coating of three-dimensional organic and inorganic surfaces with biocidal copper alloys. Our study demonstrates that the macroscale surface roughness generated by the thermal spray process enhances the biocidal activity of copper alloys compared with the nanoscale surface roughness of copper sheet metals. Moreover, the coating surface topography provides conditions for the rapid formation of organic copper phosphate nanocrystals/nanoflowers. © 2012 The Society for Applied Microbiology.

Characterization and growth analysis of two types of thin films formed on copper surfaces: An inorganic chromium containing film and an organic film formed via reduction of diazonium ions

NASA Astrophysics Data System (ADS)

Hurley, Belinda Louise

Surface enhanced Raman scattering was used to observe interactions of dilute CrVI solutions with silver and copper surfaces in situ. Using silver as a model surface, CrIII was observed at the near monolayer level, and the spectra were compared to those from CrIII oxyhydroxide species and CrIII/Cr VI mixed oxide. Similar experiments were conducted with copper surfaces and 785 nm excitation. Upon exposure of a copper surface to CrVI solution, the characteristic copper oxide Raman bands disappeared, and a Cr III band increased in intensity over a period of ˜20 hours. The intensity of the CrIII band on copper became self limiting after the formation of several CrIII monolayers, as supported by chronoamperometry experiments. This CrIII spectrum was stable after CrVI was removed from the solution provided the potential remained negative of -200 mV vs. Ag/AgCl. The results support the conclusion that CrVI is reductively adsorbed to copper at the near neutral pH and open circuit potentials expected for Cu/Al alloys in field applications. The CrIII film is stable and strongly inhibits oxygen reduction at the treated copper surface. Copper surfaces and polished Aluminum Alloy 2024 T3 substrates were derivatized at open circuit potential with arenediazonium salts in both aprotic and aqueous media. Raman spectroscopy confirmed the presence of a derivatized film on the substrates before and after exposure to boiling water and sonication in acetone. Preliminary experiments to test these films for corrosion inhibition proved unsuccessful. Aluminum and copper substrates were prepared and used for x-ray photoelectron spectroscopy (XPS) analysis of the derivatization results. In the copper experiments, one surface was native oxide copper, predominantly in the form of Cu2O, and one surface was predominantly Cu 0. Results of the XPS analysis indicate the presence of a Cu-O-C linkage and possibly a Cu-C covalent bond between the aryl ring and the copper substrate. XPS results also indicate the formation of multilayers on both types of copper surfaces with different percentages of azo coupling within the multilayers on the two surfaces. These easily prepared, covalently bonded organic films could be used for applications currently fulfilled with self-absorbed monolayers and Langmuir Blodgett films.

Process for electrically interconnecting electrodes

DOEpatents

Carey, Paul G.; Thompson, Jesse B.; Colella, Nicolas J.; Williams, Kenneth A.

2002-01-01

Electrical interconnects for solar cells or other electronic components using a silver-silicone paste or a lead-tin (Pb--Sn) no-clean fluxless solder cream, whereby the high breakage of thin (<6 mil thick) solar cells using conventional solder interconnect is eliminated. The interconnects of this invention employs copper strips which are secured to the solar cells by a silver-silicone conductive paste which can be used at room temperature, or by a Pb--Sn solder cream which eliminates undesired residue on the active surfaces of the solar cells. Electrical testing using the interconnects of this invention has shown that no degradation of the interconnects developed under high current testing, while providing a very low contact resistance value.

Antimicrobial copper alloy surfaces are effective against vegetative but not sporulated cells of gram-positive Bacillus subtilis.

PubMed

San, Kaungmyat; Long, Janet; Michels, Corinne A; Gadura, Nidhi

2015-10-01

This study explores the role of membrane phospholipid peroxidation in the copper alloy mediated contact killing of Bacillus subtilis, a spore-forming gram-positive bacterial species. We found that B. subtilis endospores exhibited significant resistance to copper alloy surface killing but vegetative cells were highly sensitive to copper surface exposure. Cell death and lipid peroxidation occurred in B. subtilis upon copper alloy surface exposure. In a sporulation-defective strain carrying a deletion of almost the entire SpoIIA operon, lipid peroxidation directly correlated with cell death. Moreover, killing and lipid peroxidation initiated immediately and at a constant rate upon exposure to the copper surface without the delay observed previously in E. coli. These findings support the hypothesis that membrane lipid peroxidation is the initiating event causing copper surface induced cell death of B. subtilis vegetative cells. The findings suggest that the observed differences in the kinetics of copper-induced killing compared to E. coli result from differences in cell envelop structure. As demonstrated in E. coli, DNA degradation was shown to be a secondary effect of copper exposure in a B. subtilis sporulation-defective strain. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Antimicrobial copper alloy surfaces are effective against vegetative but not sporulated cells of gram-positive Bacillus subtilis

PubMed Central

San, Kaungmyat; Long, Janet; Michels, Corinne A; Gadura, Nidhi

2015-01-01

This study explores the role of membrane phospholipid peroxidation in the copper alloy mediated contact killing of Bacillus subtilis, a spore-forming gram-positive bacterial species. We found that B. subtilis endospores exhibited significant resistance to copper alloy surface killing but vegetative cells were highly sensitive to copper surface exposure. Cell death and lipid peroxidation occurred in B. subtilis upon copper alloy surface exposure. In a sporulation-defective strain carrying a deletion of almost the entire SpoIIA operon, lipid peroxidation directly correlated with cell death. Moreover, killing and lipid peroxidation initiated immediately and at a constant rate upon exposure to the copper surface without the delay observed previously in E. coli. These findings support the hypothesis that membrane lipid peroxidation is the initiating event causing copper surface induced cell death of B. subtilis vegetative cells. The findings suggest that the observed differences in the kinetics of copper-induced killing compared to E. coli result from differences in cell envelop structure. As demonstrated in E. coli, DNA degradation was shown to be a secondary effect of copper exposure in a B. subtilis sporulation-defective strain. PMID:26185055

Effect of surface etching and electrodeposition of copper on nitinol

NASA Astrophysics Data System (ADS)

Ramos-Moore, E.; Rosenkranz, A.; Matamala, L. F.; Videla, A.; Durán, A.; Ramos-Grez, J.

2017-10-01

Nitinol-based materials are very promising for medical and dental applications since those materials can combine shape memory, corrosion resistance, biocompatibility and antibacterial properties. In particular, surface modifications and coating deposition can be used to tailor and to unify those properties. We report preliminary results on the study of the effect of surface etching and electrodeposition of Copper on Nitinol using optical, chemical and thermal techniques. The results show that surface etching enhances the surface roughness of Nitinol, induces the formation of Copper-based compounds at the Nitinol-Copper interface, reduces the austenitic-martensitic transformations enthalpies and reduces the Copper coating roughness. Further studies are needed in order to highlight the influence of the electrodeposited Copper on the memory shape properties of NiTi.

Effect of oxygen, methyl mercaptan, and methyl chloride on friction behavior of copper-iron contacts

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1978-01-01

Sliding friction experiments were conducted with an iron rider on a copper disk and a copper rider on an iron disk. The sputter cleaned iron and copper disk surfaces were saturated with oxygen, methyl mercaptan, and methyl chloride at atmospheric pressure. Auger emission spectroscopy was used to monitor the surfaces. Lower friction was obtained in all experiments with the copper rider sliding on the iron disk than when the couple was reversed. For both iron and copper disks, methyl mercaptan gave the best surface coverage and was most effective in reducing friction. For both iron and copper disks, methyl chloride was the least effective in reducing friction. With sliding, copper transferred to iron and iron to copper.

Copper@carbon coaxial nanowires synthesized by hydrothermal carbonization process from electroplating wastewater and their use as an enzyme-free glucose sensor.

PubMed

Zhao, Yuxin; He, Zhaoyang; Yan, Zifeng

2013-01-21

In the pursuit of electrocatalysts with great economic and ecological values for non-enzymatic glucose sensors, one-dimensional copper@carbon (Cu@C) core-shell coaxial nanowires (NWs) have been successfully prepared via a simple continuous flow wet-chemistry approach from electroplating wastewater. The as-obtained products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy and Raman spectroscopy. The electrocatalytic activity of the modified electrodes by Cu@C NWs towards glucose oxidation was investigated by cyclic voltammetry and chronoamperometry. It was found that the as-obtained Cu@C NWs showed good electrochemical properties and could be used as an electrochemical sensor for the detection of glucose molecules. Compared to the other electrodes including the bare Nafion/glassy carbon electrode (GCE) and several hot hybrid nanostructures modified GCE, a substantial decrease in the overvoltage of the glucose oxidation was observed at the Cu@C NWs electrodes with oxidation starting at ca. 0.20 V vs. Ag/AgCl (3 M KCl). At an applied potential of 0.65 V, Cu@C NWs electrodes had a high and reproducible sensitivity of 437.8 µA cm(-2) mM(-1) to glucose. Linear responses were obtained with a detection limit of 50 nM. More importantly, the proposed electrode also had good stability, high resistance against poisoning by chloride ion and commonly interfering species. These good analytical performances make Cu@C NWs promising for the future development of enzyme-free glucose sensors.

Electroactivity of phototrophic river biofilms and constitutive cultivable bacteria.

PubMed

Lyautey, Emilie; Cournet, Amandine; Morin, Soizic; Boulêtreau, Stéphanie; Etcheverry, Luc; Charcosset, Jean-Yves; Delmas, François; Bergel, Alain; Garabetian, Frédéric

2011-08-01

Electroactivity is a property of microorganisms assembled in biofilms that has been highlighted in a variety of environments. This characteristic was assessed for phototrophic river biofilms at the community scale and at the bacterial population scale. At the community scale, electroactivity was evaluated on stainless steel and copper alloy coupons used both as biofilm colonization supports and as working electrodes. At the population scale, the ability of environmental bacterial strains to catalyze oxygen reduction was assessed by cyclic voltammetry. Our data demonstrate that phototrophic river biofilm development on the electrodes, measured by dry mass and chlorophyll a content, resulted in significant increases of the recorded potentials, with potentials of up to +120 mV/saturated calomel electrode (SCE) on stainless steel electrodes and +60 mV/SCE on copper electrodes. Thirty-two bacterial strains isolated from natural phototrophic river biofilms were tested by cyclic voltammetry. Twenty-five were able to catalyze oxygen reduction, with shifts of potential ranging from 0.06 to 0.23 V, cathodic peak potentials ranging from -0.36 to -0.76 V/SCE, and peak amplitudes ranging from -9.5 to -19.4 μA. These isolates were diversified phylogenetically (Actinobacteria, Firmicutes, Bacteroidetes, and Alpha-, Beta-, and Gammaproteobacteria) and exhibited various phenotypic properties (Gram stain, oxidase, and catalase characteristics). These data suggest that phototrophic river biofilm communities and/or most of their constitutive bacterial populations present the ability to promote electronic exchange with a metallic electrode, supporting the following possibilities: (i) development of electrochemistry-based sensors allowing in situ phototrophic river biofilm detection and (ii) production of microbial fuel cell inocula under oligotrophic conditions.

Multimaterial 3D Printing of Graphene-Based Electrodes for Electrochemical Energy Storage Using Thermoresponsive Inks.

PubMed

Rocha, Victoria G; García-Tuñón, Esther; Botas, Cristina; Markoulidis, Foivos; Feilden, Ezra; D'Elia, Eleonora; Ni, Na; Shaffer, Milo; Saiz, Eduardo

2017-10-25

The current lifestyles, increasing population, and limited resources result in energy research being at the forefront of worldwide grand challenges, increasing the demand for sustainable and more efficient energy devices. In this context, additive manufacturing brings the possibility of making electrodes and electrical energy storage devices in any desired three-dimensional (3D) shape and dimensions, while preserving the multifunctional properties of the active materials in terms of surface area and conductivity. This paves the way to optimized and more efficient designs for energy devices. Here, we describe how three-dimensional (3D) printing will allow the fabrication of bespoke devices, with complex geometries, tailored to fit specific requirements and applications, by designing water-based thermoresponsive inks to 3D-print different materials in one step, for example, printing the active material precursor (reduced chemically modified graphene (rCMG)) and the current collector (copper) for supercapacitors or anodes for lithium-ion batteries. The formulation of thermoresponsive inks using Pluronic F127 provides an aqueous-based, robust, flexible, and easily upscalable approach. The devices are designed to provide low resistance interface, enhanced electrical properties, mechanical performance, packing of rCMG, and low active material density while facilitating the postprocessing of the multicomponent 3D-printed structures. The electrode materials are selected to match postprocessing conditions. The reduction of the active material (rCMG) and sintering of the current collector (Cu) take place simultaneously. The electrochemical performance of the rCMG-based self-standing binder-free electrode and the two materials coupled rCMG/Cu printed electrode prove the potential of multimaterial printing in energy applications.

Copper-Based Metal-Organic Porous Materials for CO2 Electrocatalytic Reduction to Alcohols.

PubMed

Albo, Jonathan; Vallejo, Daniel; Beobide, Garikoitz; Castillo, Oscar; Castaño, Pedro; Irabien, Angel

2017-03-22

The electrocatalytic reduction of CO 2 has been investigated using four Cu-based metal-organic porous materials supported on gas diffusion electrodes, namely, (1) HKUST-1 metal-organic framework (MOF), [Cu 3 (μ 6 -C 9 H 3 O 6 ) 2 ] n ; (2) CuAdeAce MOF, [Cu 3 (μ 3 -C 5 H 4 N 5 ) 2 ] n ; (3) CuDTA mesoporous metal-organic aerogel (MOA), [Cu(μ-C 2 H 2 N 2 S 2 )] n ; and (4) CuZnDTA MOA, [Cu 0.6 Zn 0.4 (μ-C 2 H 2 N 2 S 2 )] n . The electrodes show relatively high surface areas, accessibilities, and exposure of the Cu catalytic centers as well as favorable electrocatalytic CO 2 reduction performance, that is, they have a high efficiency for the production of methanol and ethanol in the liquid phase. The maximum cumulative Faradaic efficiencies for CO 2 conversion at HKUST-1-, CuAdeAce-, CuDTA-, and CuZnDTA-based electrodes are 15.9, 1.2, 6, and 9.9 %, respectively, at a current density of 10 mA cm -2 , an electrolyte-flow/area ratio of 3 mL min cm -2 , and a gas-flow/area ratio of 20 mL min cm -2 . We can correlate these observations with the structural features of the electrodes. Furthermore, HKUST-1- and CuZnDTA-based electrodes show stable electrocatalytic performance for 17 and 12 h, respectively. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of Prototype Production ESR Facilities

DTIC Science & Technology

1977-07-01

CJISTHIBUTION STATEMENT (ot (he aUxIr&cl entnred in lil^ck 21), If ctlfferert from Wfv.rtj 18. SiJPPi EMENTARV NOTES M9. Kfc y WORDS...Unlike in conventional foundry methods, electroslag castings are made in water-cooled metal molds by remelting of consumable electrodes in... CONSUMABLE ELECTRODE TOP MOLD SLAQ POOL MOLTEN METAL POOL LEVEL DETECTOR MOLTEN METAL POOL ESP INCrOT COPPER LINER mTER JACKET

Contact Killing of Bacteria on Copper Is Suppressed if Bacterial-Metal Contact Is Prevented and Is Induced on Iron by Copper Ions

PubMed Central

Mathews, Salima; Hans, Michael

2013-01-01

Bacteria are rapidly killed on copper surfaces, and copper ions released from the surface have been proposed to play a major role in the killing process. However, it has remained unclear whether contact of the bacteria with the copper surface is also an important factor. Using laser interference lithography, we engineered copper surfaces which were covered with a grid of an inert polymer which prevented contact of the bacteria with the surface. Using Enterococcus hirae as a model organism, we showed that the release of ionic copper from these modified surfaces was not significantly reduced. In contrast, killing of bacteria was strongly attenuated. When E. hirae cells were exposed to a solid iron surface, the loss of cell viability was the same as on glass. However, exposing cells to iron in the presence of 4 mM CuSO4 led to complete killing in 100 min. These experiments suggest that contact killing proceeds by a mechanism whereby the metal-bacterial contact damages the cell envelope, which, in turn, makes the cells susceptible to further damage by copper ions. PMID:23396344

Optimizing C–C Coupling on Oxide-Derived Copper Catalysts for Electrochemical CO 2 Reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lum, Yanwei; Yue, Binbin; Lobaccaro, Peter

Here, copper electrodes, prepared by reduction of oxidized metallic copper, have been reported to exhibit higher activity for the electrochemical reduction of CO 2 and better selectivity toward C 2 and C 3 (C 2+) products than metallic copper that has not been preoxidized. We report here an investigation of the effects of four different preparations of oxide-derived electrocatalysts on their activity and selectivity for CO 2 reduction, with particular attention given to the selectivity to C 2+ products. All catalysts were tested for CO 2 reduction in 0.1 M KHCO 3 and 0.1 M CsHCO 3 at applied voltagesmore » in the range from –0.7 to –1.0 V vs RHE. The best performing oxide-derived catalysts show up to ~70% selectivity to C 2+ products and only ~3% selectivity to C 1 products at –1.0 V vs RHE when CsHCO 3 is used as the electrolyte. In contrast, the selectivity to C 2+ products decreases to ~56% for the same catalysts tested in KHCO 3. By studying all catalysts under identical conditions, the key factors affecting product selectivity could be discerned. These efforts reveal that the surface area of the oxide-derived layer is a critical parameter affecting selectivity. A high selectivity to C 2+ products is attained at an overpotential of –1 V vs RHE by operating at a current density sufficiently high to achieve a moderately high pH near the catalyst surface but not so high as to cause a significant reduction in the local concentration of CO 2. On the basis of recent theoretical studies, a high pH suppresses the formation of C 1 relative to C 2+ products. At the same time, however, a high local CO 2 concentration is necessary for the formation of C 2+ products.« less

Optimizing C–C Coupling on Oxide-Derived Copper Catalysts for Electrochemical CO 2 Reduction

DOE PAGES

Lum, Yanwei; Yue, Binbin; Lobaccaro, Peter; ...

2017-07-06

Here, copper electrodes, prepared by reduction of oxidized metallic copper, have been reported to exhibit higher activity for the electrochemical reduction of CO 2 and better selectivity toward C 2 and C 3 (C 2+) products than metallic copper that has not been preoxidized. We report here an investigation of the effects of four different preparations of oxide-derived electrocatalysts on their activity and selectivity for CO 2 reduction, with particular attention given to the selectivity to C 2+ products. All catalysts were tested for CO 2 reduction in 0.1 M KHCO 3 and 0.1 M CsHCO 3 at applied voltagesmore » in the range from –0.7 to –1.0 V vs RHE. The best performing oxide-derived catalysts show up to ~70% selectivity to C 2+ products and only ~3% selectivity to C 1 products at –1.0 V vs RHE when CsHCO 3 is used as the electrolyte. In contrast, the selectivity to C 2+ products decreases to ~56% for the same catalysts tested in KHCO 3. By studying all catalysts under identical conditions, the key factors affecting product selectivity could be discerned. These efforts reveal that the surface area of the oxide-derived layer is a critical parameter affecting selectivity. A high selectivity to C 2+ products is attained at an overpotential of –1 V vs RHE by operating at a current density sufficiently high to achieve a moderately high pH near the catalyst surface but not so high as to cause a significant reduction in the local concentration of CO 2. On the basis of recent theoretical studies, a high pH suppresses the formation of C 1 relative to C 2+ products. At the same time, however, a high local CO 2 concentration is necessary for the formation of C 2+ products.« less

Nanowire-Modified Three-Dimensional Electrode Enabling Low-Voltage Electroporation for Water Disinfection.

PubMed

Huo, Zheng-Yang; Xie, Xing; Yu, Tong; Lu, Yun; Feng, Chao; Hu, Hong-Ying

2016-07-19

More than 10% of the people in the world still suffer from inadequate access to clean water. Traditional water disinfection methods (e.g., chlorination and ultraviolet radiation) include concerns about the formation of carcinogenic disinfection byproducts (DBPs), pathogen reactivation, and/or excessive energy consumption. Recently, a nanowire-assisted electroporation-disinfection method was introduced as an alternative. Here, we develop a new copper oxide nanowire (CuONW)-modified three-dimensional copper foam electrode using a facile thermal oxidation approach. An electroporation-disinfection cell (EDC) equipped with two such electrodes has achieved superior disinfection performance (>7 log removal and no detectable bacteria in the effluent). The disinfection mechanism of electroporation guarantees an exceedingly low operation voltage (1 V) and level of energy consumption (25 J L(-1)) with a short contact time (7 s). The low operation voltage avoids chlorine generation and thus reduces the potential of DBP formation. Because of irreversible electroporation damage on cell membranes, no regrowth and/or reactivation of bacteria occurs during storage after EDC treatment. Water disinfection using EDCs has great potential for practical applications.

Sporicidal efficacy of thermal-sprayed copper alloy coating.

PubMed

Shafaghi, Romina; Mostaghimi, Javad; Pershin, Valerian; Ringuette, Maurice

2017-05-01

Approximately 200 000 Canadians acquire healthcare-associated bacterial infections each year and several-fold more acquire food-borne bacterial illnesses. Bacterial spores are particularly problematic because they can survive on surfaces for several months. Owing to its sporicidal activity, copper alloy sheet metal is sometimes used in hospital settings, but its widespread use is limited by cost and incompatibility with complex furniture and instrument designs and topographies. A potential alternative is the use of thermal spray technology to coat surfaces with copper alloys. We compared the sporicidal activity of thermally sprayed copper alloy on stainless steel with that of copper alloy sheet metal against Bacillus subtilis spores. Spores remained intact for at least 1 week on uncoated stainless steel, whereas spore fragmentation was initiated within 2 h of exposure to either copper surface. Less than 15% of spores were viable 2 h after exposure to either copper surface, as compared with stainless steel. By day 7, only degraded spores and petal-like nanoflowers were present on the copper surfaces. Nanoflowers, which are laminar arrangements of thin crystal sheets composed of carbon - copper phosphate, appeared to be derived from the degraded spores. Altogether, these results indicate that a thermal-sprayed copper alloy coating on stainless steel provides sporicidal activity similar to that afforded by copper alloy sheet metal.

Copper in the sediment and sea surface microlayer near a fallowed, open-net fish farm.

PubMed

Loucks, Ronald H; Smith, Ruth E; Fisher, Clyde V; Fisher, E Brian

2012-09-01

Sediment and sea surface microlayer samples near an open-net salmon farm in Nova Scotia, were analysed for copper. Copper is a constituent of the feed and is an active ingredient of anti-foulants. The salmon farm was placed in fallow after 15 years of production. Sampling was pursued over 27 months. Elevated copper concentrations in the sediments indicated the farm site as a source. Bubble flotation due to gas-emitting sediments from eutrophication is a likely process for accumulating copper in the sea surface microlayer at enriched concentrations. Elevated and enriched concentrations in the sea surface microlayer over distance from the farm site led, as a result of wind-drift, to an enlarged farm footprint. The levels of copper in both sediments and sea surface microlayer exceeded guidelines for protection of marine life. Over the 27 months period, copper levels persisted in the sediments and decreased gradually in the sea surface microlayer. Copyright © 2012 Elsevier Ltd. All rights reserved.

Elucidation of the Oxygen Reduction Volcano in Alkaline Media using a Copper-Platinum(111) Alloy.

PubMed

Jensen, Kim D; Tymoczko, Jakub; Rossmeisl, Jan; Bandarenka, Aliaksandr S; Chorkendorff, Ib; Escudero-Escribano, María; Stephens, Ifan E L

2018-03-05

The relationship between the binding of the reaction intermediates and oxygen reduction activity in alkaline media was experimentally explored. By introducing Cu into the 2nd surface layer of a Pt(111) single crystal, the surface reactivity was tuned. In both 0.1 m NaOH and 0.1 m KOH, the optimal catalyst should exhibit OH binding circa 0.1 eV weaker than Pt(111), via a Sabatier volcano; this observation suggests that the reaction is mediated via the same surface bound intermediates as in acid, in contrast to previous reports. In 0.1 m KOH, the alloy catalyst at the peak of the volcano exhibits a maximum activity of 101±8 mA cm -2 at 0.9 V vs. a reversible hydrogen electrode (RHE). This activity constitutes a circa 60-fold increase over Pt(111) in 0.1 m HClO 4 . © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ag/Au/Polypyrrole Core-shell Nanowire Network for Transparent, Stretchable and Flexible Supercapacitor in Wearable Energy Devices

NASA Astrophysics Data System (ADS)

Moon, Hyunjin; Lee, Habeom; Kwon, Jinhyeong; Suh, Young Duk; Kim, Dong Kwan; Ha, Inho; Yeo, Junyeob; Hong, Sukjoon; Ko, Seung Hwan

2017-02-01

Transparent and stretchable energy storage devices have attracted significant interest due to their potential to be applied to biocompatible and wearable electronics. Supercapacitors that use the reversible faradaic redox reaction of conducting polymer have a higher specific capacitance as compared with electrical double-layer capacitors. Typically, the conducting polymer electrode is fabricated through direct electropolymerization on the current collector. However, no research have been conducted on metal nanowires as current collectors for the direct electropolymerization, even though the metal nanowire network structure has proven to be superior as a transparent, flexible, and stretchable electrode platform because the conducting polymer’s redox potential for polymerization is higher than that of widely studied metal nanowires such as silver and copper. In this study, we demonstrated a highly transparent and stretchable supercapacitor by developing Ag/Au/Polypyrrole core-shell nanowire networks as electrode by coating the surface of Ag NWs with a thin layer of gold, which provide higher redox potential than the electropolymerizable monomer. The Ag/Au/Polypyrrole core-shell nanowire networks demonstrated superior mechanical stability under various mechanical bending and stretching. In addition, proposed supercapacitors showed fine optical transmittance together with fivefold improved areal capacitance compared to pristine Ag/Au core-shell nanowire mesh-based supercapacitors.

Ag/Au/Polypyrrole Core-shell Nanowire Network for Transparent, Stretchable and Flexible Supercapacitor in Wearable Energy Devices

PubMed Central

Moon, Hyunjin; Lee, Habeom; Kwon, Jinhyeong; Suh, Young Duk; Kim, Dong Kwan; Ha, Inho; Yeo, Junyeob; Hong, Sukjoon; Ko, Seung Hwan

2017-01-01

Transparent and stretchable energy storage devices have attracted significant interest due to their potential to be applied to biocompatible and wearable electronics. Supercapacitors that use the reversible faradaic redox reaction of conducting polymer have a higher specific capacitance as compared with electrical double-layer capacitors. Typically, the conducting polymer electrode is fabricated through direct electropolymerization on the current collector. However, no research have been conducted on metal nanowires as current collectors for the direct electropolymerization, even though the metal nanowire network structure has proven to be superior as a transparent, flexible, and stretchable electrode platform because the conducting polymer’s redox potential for polymerization is higher than that of widely studied metal nanowires such as silver and copper. In this study, we demonstrated a highly transparent and stretchable supercapacitor by developing Ag/Au/Polypyrrole core-shell nanowire networks as electrode by coating the surface of Ag NWs with a thin layer of gold, which provide higher redox potential than the electropolymerizable monomer. The Ag/Au/Polypyrrole core-shell nanowire networks demonstrated superior mechanical stability under various mechanical bending and stretching. In addition, proposed supercapacitors showed fine optical transmittance together with fivefold improved areal capacitance compared to pristine Ag/Au core-shell nanowire mesh-based supercapacitors. PMID:28155913

Electrochemical properties and electrocatalytic activity of conducting polymer/copper nanoparticles supported on reduced graphene oxide composite

NASA Astrophysics Data System (ADS)

Ehsani, Ali; Jaleh, Babak; Nasrollahzadeh, Mahmoud

2014-07-01

Reduced graphene oxide (rGO) was used to support Cu nanoparticles. As electro-active electrodes for supercapacitors composites of reduced graphene oxide/Cu nanoparticles (rGO/CuNPs) and polytyramine (PT) with good uniformity are prepared by electropolymerization. Composite of rGO/CuNPs-PT was synthesized by cyclic voltammetry (CV) methods and electrochemical properties of film were investigated by using electrochemical techniques. The results show that, the rGO/CuNPs-PT/G has better capacitance performance. This is mainly because of the really large surface area and the better electronic and ionic conductivity of rGO/CuNPs-PT/G, which lead to greater double-layer capacitance and faradic pseudo capacitance. Modified graphite electrodes (rGO/CuNPs-PT/G) were examined for their redox process and electrocatalytic activities towards the oxidation of methanol in alkaline solutions. The methods of cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) were employed. In comparison with a Cu-PT/G (Graphite), rGO/CuNPs-PT/G modified electrode shows a significantly higher response for methanol oxidation. A mechanism based on the electro-chemical generation of Cu(III) active sites and their subsequent consumptions by methanol have been discussed.

Lack of Involvement of Fenton Chemistry in Death of Methicillin-Resistant and Methicillin-Sensitive Strains of Staphylococcus aureus and Destruction of Their Genomes on Wet or Dry Copper Alloy Surfaces

PubMed Central

2016-01-01

The pandemic of hospital-acquired infections caused by methicillin-resistant Staphylococcus aureus (MRSA) has declined, but the evolution of strains with enhanced virulence and toxins and the increase of community-associated infections are still a threat. In previous studies, 107 MRSA bacteria applied as simulated droplet contamination were killed on copper and brass surfaces within 90 min. However, contamination of surfaces is often via finger tips and dries rapidly, and it may be overlooked by cleaning regimes (unlike visible droplets). In this new study, a 5-log reduction of a hardy epidemic strain of MRSA (epidemic methicillin-resistant S. aureus 16 [EMRSA-16]) was observed following 10 min of contact with copper, and a 4-log reduction was observed on copper nickel and cartridge brass alloys in 15 min. A methicillin-sensitive S. aureus (MSSA) strain from an osteomyelitis patient was killed on copper surfaces in 15 min, and 4-log and 3-log reductions occurred within 20 min of contact with copper nickel and cartridge brass, respectively. Bacterial respiration was compromised on copper surfaces, and superoxide was generated as part of the killing mechanism. In addition, destruction of genomic DNA occurs on copper and brass surfaces, allaying concerns about horizontal gene transfer and copper resistance. Incorporation of copper alloy biocidal surfaces may help to reduce the spread of this dangerous pathogen. PMID:26826226

Signal processing with a summing operational amplifier in multicomponent potentiometric titrations.

PubMed

Parczewski, A

1987-06-01

It has been proved that application of two indicator electrodes connected to the ordinary titration apparatus through an auxiliary electronic device (a summing operational amplifier) significantly extends the scope of multicomponent potentiometric titrations in which the analytes are determined simultaneously from a single titration curve. For each analyte there is a corresponding potential jump on the titration curve. By application of the proposed auxiliary device, the sum of the electrode potentials is measured. The device also enables the relative sizes of the potential jumps at the end-points on the titration curve to be varied. The advantages of the proposed signal processing are exemplified by complexometric potentiometric titrations of Fe(III) and Cu(II) in mixtures, with a platinum electrode and a copper ion-selective electrode as the indicator electrodes.

Sensing of volatile organic compounds by copper phthalocyanine thin films

NASA Astrophysics Data System (ADS)

Ridhi, R.; Saini, G. S. S.; Tripathi, S. K.

2017-02-01

Thin films of copper phthalocyanine have been deposited by thermal evaporation technique. We have subsequently exposed these films to the vapours of methanol, ethanol and propanol. Optical absorption, infrared spectra and electrical conductivities of these films before and after exposure to chemical vapours have been recorded in order to study their sensing mechanisms towards organic vapours. These films exhibit maximum sensing response to methanol while low sensitivities of the films towards ethanol and propanol have been observed. The changes in sensitivities have been correlated with presence of carbon groups in the chemical vapours. The effect of different types of electrodes on response-recovery times of the thin film with organic vapours has been studied and compared. The electrodes gap distance affects the sensitivity as well as response-recovery time values of the thin films.

A novel nonenzymatic amperometric hydrogen peroxide sensor based on CuO@Cu2O nanowires embedded into poly(vinyl alcohol).

PubMed

Chirizzi, Daniela; Guascito, Maria Rachele; Filippo, Emanuela; Tepore, Antonio

2016-01-15

A new, very simple, rapid and inexpensive nonenzymatic amperometric sensor for hydrogen peroxide (H2O2) detection is proposed. It is based on the immobilization of cupric/cuprous oxide core shell nanowires (CuO@Cu2O-NWs) in a poly(vinyl alcohol) (PVA) matrix directly drop casted on a glassy carbon electrode surface to make a CuO@Cu2O core shell like NWs PVA embedded (CuO@Cu2O-NWs/PVA) sensor. CuO nanowires with mean diameters of 120-170nm and length in the range 2-5μm were grown by a simple catalyst-free thermal oxidation process based on resistive heating of pure copper wires at ambient conditions. The oxidation process of the copper wire surface led to the formation of a three layered structure: a thick Cu2O bottom layer, a CuO thin intermediate layer and CuO nanowires. CuO nanowires were carefully scratched from Cu2O layer with a sharp knife, dispersed into ethanol and sonicated. Then, the NWs were embedded in PVA matrix. The morphological and spectroscopic characterization of synthesized CuO-NWs and CuO@Cu2O-NWs/PVA were performed by transmission electron microscopy (TEM), selected area diffraction pattern (SAD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. Moreover a complete electrochemical characterization of these new CuO@Cu2O-NWs/PVA modified glassy carbon electrodes was performed by Cyclic Voltammetry (CV) and Cronoamperometry (CA) in phosphate buffer (pH=7; I=0.2) to investigate the sensing properties of this material against H2O2. The electrochemical performances of proposed sensors as high sensitivity, fast response, reproducibility and selectivity make them suitable for the quantitative determination of hydrogen peroxide substrate in batch analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of GEM-based detectors in full-field XRF imaging

NASA Astrophysics Data System (ADS)

Dąbrowski, W.; Fiutowski, T.; Frączek, P.; Koperny, S.; Lankosz, M.; Mendys, A.; Mindur, B.; Świentek, K.; Wiącek, P.; Wróbel, P. M.

2016-12-01

X-ray fluorescence spectroscopy (XRF) is a commonly used technique for non-destructive elemental analysis of cultural heritage objects. It can be applied to investigations of provenance of historical objects as well as to studies of art techniques. While the XRF analysis can be easily performed locally using standard available equipment there is a growing interest in imaging of spatial distribution of specific elements. Spatial imaging of elemental distrbutions is usually realised by scanning an object with a narrow focused X-ray excitation beam and measuring characteristic fluorescence radiation using a high energy resolution detector, usually a silicon drift detector. Such a technique, called macro-XRF imaging, is suitable for investigation of flat surfaces but it is time consuming because the spatial resolution is basically determined by the spot size of the beam. Another approach is the full-field XRF, which is based on simultaneous irradiation and imaging of large area of an object. The image of the investigated area is projected by a pinhole camera on a position-sensitive and energy dispersive detector. The infinite depth of field of the pinhole camera allows one, in principle, investigation of non-flat surfaces. One of possible detectors to be employed in full-field XRF imaging is a GEM based detector with 2-dimensional readout. In the paper we report on development of an imaging system equipped with a standard 3-stage GEM detector of 10 × 10 cm2 equipped with readout electronics based on dedicated full-custom ASICs and DAQ system. With a demonstrator system we have obtained 2-D spatial resolution of the order of 100 μm and energy resolution at a level of 20% FWHM for 5.9 keV . Limitations of such a detector due to copper fluorescence radiation excited in the copper-clad drift electrode and GEM foils is discussed and performance of the detector using chromium-clad electrodes is reported.

Electrodeposition of copper on a Pt(111) electrode in sulfuric acid containing poly(ethylene glycol) and chloride ions as probed by in situ STM.

PubMed

Fu, YunLin; Pao, Te; Chen, Sih-Zih; Yau, ShuehLin; Dow, Wei-Ping; Lee, Yuh-Lang

2012-07-03

This study employed real-time in situ STM imaging to examine the adsorption of PEG molecules on Pt(111) modified by a monolayer of copper adatoms and the subsequent bulk Cu deposition in 1 M H(2)SO(4) + 1 mM CuSO(4)+ 1 mM KCl + 88 μM PEG. At the end of Cu underpotential deposition (~0.35 V vs Ag/AgCl), a highly ordered Pt(111)-(√3 × √7)-Cu + HSO(4)(-) structure was observed in 1 M H(2)SO(4) + 1 mM CuSO(4). This adlattice restructured upon the introduction of poly(ethylene glycol) (PEG, molecular weight 200) and chloride anions. At the onset potential for bulk Cu deposition (~0 V), a Pt(111)-(√3 × √3)R30°-Cu + Cl(-) structure was imaged with a tunneling current of 0.5 nA and a bias voltage of 100 mV. Lowering the tunneling current to 0.2 nA yielded a (4 × 4) structure, presumably because of adsorbed PEG200 molecules. The subsequent nucleation and deposition processes of Cu in solution containing PEG and Cl(-) were examined, revealing the nucleation of 2- to 3-nm-wide CuCl clusters on an atomically smooth Pt(111) surface at overpotentials of less than 50 mV. With larger overpotential (η > 150 mV), Cu deposition seemed to bypass the production of CuCl species, leading to layered Cu deposition, starting preferentially at step defects, followed by lateral growth to cover the entire Pt electrode surface. These processes were observed with both PEG200 and 4000, although the former tended to produce more CuCl nanoclusters. Raising [H(2)SO(4)] to 1 M substantiates the suppressing effect of PEG on Cu deposition. This STM study provided atomic- or molecular-level insight into the effect of PEG additives on the deposition of Cu.

A single-walled carbon nanotubes/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)/copper hexacyanoferrate hybrid film for high-volumetric performance flexible supercapacitors

NASA Astrophysics Data System (ADS)

Li, Jianmin; Li, Haizeng; Li, Jiahui; Wu, Guiqing; Shao, Yuanlong; Li, Yaogang; Zhang, Qinghong; Wang, Hongzhi

2018-05-01

Volumetric energy density is generally considered to be detrimental to the actual application of supercapacitors, which has provoked a range of research work on increasing the packing density of electrodes. Herein, we fabricate a free-standing single-walled carbon nanotubes (SWCNTs)/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/copper hexacyanoferrate (CuHCF) nanoparticles (NPs) composite supercapacitor electrode, with a high packing density of 2.67 g cm-3. The pseudocapacitive CuHCF NPs are decorated onto the SWCNTs/PEDOT:PSS networks and filled in interspace to increase both of packing density and specific capacitance. This hybrid electrode exhibits a series of outstanding performances, such as high electric conductivity, ultrahigh areal and volumetric capacitances (969.8 mF cm-2 and 775.2 F cm-3 at scan rate of 5 mV s-1), long cycle life and superior rate capability. The asymmetric supercapacitor built by using the SWCNTs/PEDOT:PSS/CuHCF film as positive electrode and Mo-doped WO3/SWCNTs film as negative electrode, can deliver a high energy density of 30.08 Wh L-1 with a power density of 4.25 kW L-1 based on the total volume of the device. The approach unveiled in this study could provide important insights to improving the volumetric performance of energy storage devices and help to reach the critical targets for high rate and high power density demand applications.

Effects of copper-plasma deposition on weathering properties of wood surfaces

NASA Astrophysics Data System (ADS)

Gascón-Garrido, P.; Mainusch, N.; Militz, H.; Viöl, W.; Mai, C.

2016-03-01

Thin layers of copper micro-particles were deposited on the surfaces of Scots pine (Pinus sylvestris L.) micro-veneers using atmospheric pressure plasma to improve the resistance of the surfaces to weathering. Three different loadings of copper were established. Micro-veneers were exposed to artificial weathering in a QUV weathering tester for 0, 24, 48, 96 and 144 h following the standard EN 927-6 [1]. Mass losses after each exposure showed significant differences between copper coated and untreated micro-veneers. Tensile strength was assessed at zero span (z-strength) and finite span (f-strength) under dry conditions (20 °C, 65% RH). During 48 h, micro-veneers lost their z-strength progressively. In contrast, copper coating at highest loading imparts a photo-protective effect to wood micro-veneers during 144 h exhibiting z-strength retention of 95%. F-strength losses were similar in all copper treated and untreated micro-veneers up to 96 h. However, after 144 h, copper coated micro-veneers at highest loading showed significantly greater strength retention of 56%, while untreated micro-veneers exhibited only 38%. Infrared spectroscopy suggested that copper coating does not stabilize lignin. Inductively Coupled Plasma revealed that micro-veneers coated with the highest loading exhibited the lowest percentage of copper loss. Blue stain resistance of copper coated Scots pine following the guidelines of EN 152 [2] was performed. Additional test with different position of the coated surface was also assessed. Copper coating reduced fungal growth when coated surface is exposed in contact with vermiculite. Spores of Aureobasidium pullulans were not able to germinate on the copper coated surface positioned uppermost.

Diode-rectified multiphase AC arc for the improvement of electrode erosion characteristics

NASA Astrophysics Data System (ADS)

Tanaka, Manabu; Hashizume, Taro; Saga, Koki; Matsuura, Tsugio; Watanabe, Takayuki

2017-11-01

An innovative multiphase AC arc (MPA) system was developed on the basis of a diode-rectification technique to improve electrode erosion characteristics. Conventionally, electrode erosion in AC arc is severer than that in DC arc. This originated from the fact that the required properties for the cathode and anode are different, although an AC electrode works as the cathode and the anode periodically. To solve this problem, a separation of AC electrodes into pairs of thoriated tungsten cathode and copper anode by diode-rectification was attempted. A diode-rectified multiphase AC arc (DRMPA) system was then successfully established, resulting in a drastic improvement of the erosion characteristics. The electrode erosion rate in the DRMPA was less than one-third of that in the conventional MPA without the diode rectification. In order to clarify its erosion mechanism, electrode phenomena during discharge were visualized by a high-speed camera system with appropriate band-pass filters. Fluctuation characteristics of the electrode temperature in the DRMPA were revealed.

In situ growth of copper nanocrystals from carbonaceous microspheres with electrochemical glucose sensing properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xiaoliang; Yan, Zhengguang, E-mail: yanzg2004@gmail.com; Han, Xiaodong, E-mail: xdhan@bjut.edu.cn

2014-02-01

Graphical abstract: In situ growth of copper nanoparticles from hydrothermal copper-containing carbonaceous microspheres was induced by annealing or electron beam irradiation. Obtained micro-nano carbon/copper composite microspheres show electrochemical glucose sensing properties. - Highlights: • We synthesized carbonaceous microspheres containing non-nanoparicle copper species through a hydrothermal route. • By annealing or electron beam irradiation, copper nanoparticles would form from the carbonaceous microspheres in situ. • By controlling the annealing temperature, particle size of copper could be controlled in the range of 50–500 nm. • The annealed carbon/copper hierarchical composite microspheres were used to fabricate an electrochemical glucose sensor. - Abstract: Inmore » situ growth of copper nanocrystals from carbon/copper microspheres was observed in a well-controlled annealing or an electron beam irradiation process. Carbonaceous microspheres containing copper species with a smooth appearance were yielded by a hydrothermal synthesis using copper nitrate and ascorbic acid as reactants. When annealing the carbonaceous microspheres under inert atmosphere, copper nanoparticles were formed on carbon microspheres and the copper particle sizes can be increased to a range of 50–500 nm by altering the heating temperature. Similarly, in situ formation of copper nanocrystals from these carbonaceous microspheres was observed on the hydrothermal product carbonaceous microspheres with electron beam irradiation in a vacuum transmission electron microscopy chamber. The carbon/copper composite microspheres obtained through annealing were used to modify a glassy carbon electrode and tested as an electrochemical glucose sensor.« less

Estimating Dermal Transfer of Copper Particles from the Surfaces of Pressure-Treated Lumber and Implications for Exposure

EPA Science Inventory

Lumber pressure-treated with micronized copper was examined for the release of copper and copper micro/nanoparticles using a surface wipe method to simulate dermal transfer. In 2003, the wood industry began replacing CCA treated lumber products for residential use with copper ba...

Electrodeposition of Copper onto Polypyrrole Films: Application to Proton Reduction

NASA Astrophysics Data System (ADS)

Chikouche, Imene; Sahari, Ali; Zouaoui, Ahmed; Zegadi, Ameur

2016-09-01

In this paper, we have electrodeposited copper on polypyrrole surface. Results show that at high applied cathodic potential (>-1.8V), copper electrodeposition occurs with difficulties. The amount of electrodeposited copper is low (1.32%) and it is limited by the low polypyrrole conductivity. At this potential, poor conductivity is caused by its insulating state. However, at an applied cathodic potential of -1.2V, the polypyrrole exhibits a relatively high conductivity and copper particles are electrodeposited with large amounts (12.44%) on polypyrrole/silicon system. At high applied cathodic potential, the SEM images show clearly dispersed grains of copper, but polypyrrole surface is less occupied. At an applied cathodic potential of -1.2V, the SEM image shows that polypyrrole surface is homogenously more occupied with copper. After copper deposition, the Cu/PPy/Si system is used to catalyze the hydrogen reaction. It was found that, once the deposited copper is present with considerable amounts, the proton reduction occurs easily. As for the polypyrrole conductivity, it was found that electrodeposited copper onto PPy/Si surface affect the total conductivity.

A copper-based layered coordination polymer: synthesis, magnetic properties and electrochemical performance in supercapacitors.

PubMed

Liu, Qi; Liu, Xiuxiu; Shi, Changdong; Zhang, Yanpeng; Feng, Xuejun; Cheng, Mei-Ling; Su, Seng; Gu, Jiande

2015-11-28

A copper-based layered coordination polymer ([Cu(hmt)(tfbdc)(H2O)]; hmt = hexamethylenetetramine, tfbdc = 2,3,5,6-tetrafluoroterephthalate; Cu-LCP) has been synthesized, and it has been structurally and magnetically characterized. The Cu-LCP shows ferromagnetic interactions between the adjacent copper(II) ions. Density functional theory calculations on the special model of Cu-LCP support the occurrence of ferromagnetic interactions. As an electrode material for supercapacitors, Cu-LCP exhibits a high specific capacitance of 1274 F g(-1) at a current density of 1 A g(-1) in 1 M LiOH electrolyte, and the capacitance retention is about 88% after 2000 cycles.

Proximity charge sensing for semiconductor detectors

DOEpatents

Luke, Paul N; Tindall, Craig S; Amman, Mark

2013-10-08

A non-contact charge sensor includes a semiconductor detector having a first surface and an opposing second surface. The detector includes a high resistivity electrode layer on the first surface and a low resistivity electrode on the high resistivity electrode layer. A portion of the low resistivity first surface electrode is deleted to expose the high resistivity electrode layer in a portion of the area. A low resistivity electrode layer is disposed on the second surface of the semiconductor detector. A voltage applied between the first surface low resistivity electrode and the second surface low resistivity electrode causes a free charge to drift toward the first or second surface according to a polarity of the free charge and the voltage. A charge sensitive preamplifier coupled to a non-contact electrode disposed at a distance from the exposed high resistivity electrode layer outputs a signal in response to movement of free charge within the detector.

Design of lithium cobalt oxide electrodes with high thermal conductivity and electrochemical performance using carbon nanotubes and diamond particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Eungje; Salgado, Ruben Arash; Lee, Byeongdu

Thermal management remains one of the major challenges in the design of safe and reliable Li-ion batteries. We show that composite electrodes assembled from commercially available 100 μm long carbon nanotubes (CNTs) and LiCoO2 (LCO) particles demonstrate the in-plane thermal conductivity of 205.8 W/m*K. This value exceeds the thermal conductivity of dry conventional laminated electrodes by about three orders of magnitude. The cross-plane thermal conductivity of CNT-based electrodes is in the same range as thermal conductivities of conventional laminated electrodes. The CNT-based electrodes demonstrate a similar capacity to conventional laminated design electrodes, but revealed a better rate performance and stability.more » The introduction of diamond particles into CNT-based electrodes further improves the rate performance. Our lightweight, flexible electrode design can potentially be a general platform for fabricating polymer binder- and aluminum and copper current collector- free electrodes from a broad range of electrochemically active materials with efficient thermal management.« less

Pure and Oxidized Copper Materials as Potential Antimicrobial Surfaces for Spaceflight Activities.

PubMed

Hahn, C; Hans, M; Hein, C; Mancinelli, R L; Mücklich, F; Wirth, R; Rettberg, P; Hellweg, C E; Moeller, R

2017-12-01

Microbial biofilms can lead to persistent infections and degrade a variety of materials, and they are notorious for their persistence and resistance to eradication. During long-duration space missions, microbial biofilms present a danger to crew health and spacecraft integrity. The use of antimicrobial surfaces provides an alternative strategy for inhibiting microbial growth and biofilm formation to conventional cleaning procedures and the use of disinfectants. Antimicrobial surfaces contain organic or inorganic compounds, such as antimicrobial peptides or copper and silver, that inhibit microbial growth. The efficacy of wetted oxidized copper layers and pure copper surfaces as antimicrobial agents was tested by applying cultures of Escherichia coli and Staphylococcus cohnii to these metallic surfaces. Stainless steel surfaces were used as non-inhibitory control surfaces. The production of reactive oxygen species and membrane damage increased rapidly within 1 h of exposure on pure copper surfaces, but the effect on cell survival was negligible even after 2 h of exposure. However, longer exposure times of up to 4 h led to a rapid decrease in cell survival, whereby the survival of cells was additionally dependent on the exposed cell density. Finally, the release of metal ions was determined to identify a possible correlation between copper ions in suspension and cell survival. These measurements indicated a steady increase of free copper ions, which were released indirectly by cells presumably through excreted complexing agents. These data indicate that the application of antimicrobial surfaces in spaceflight facilities could improve crew health and mitigate material damage caused by microbial contamination and biofilm formation. Furthermore, the results of this study indicate that cuprous oxide layers were superior to pure copper surfaces related to the antimicrobial effect and that cell density is a significant factor that influences the time dependence of antimicrobial activity. Key Words: Contact killing-E. coli-S. cohnii-Antimicrobial copper surfaces-Copper oxide layers-Human health-Planetary protection. Astrobiology 17, 1183-1191.

Cleaning and passivation of copper surfaces to remove surface radioactivity and prevent oxide formation

NASA Astrophysics Data System (ADS)

Hoppe, E. W.; Seifert, A.; Aalseth, C. E.; Bachelor, P. P.; Day, A. R.; Edwards, D. J.; Hossbach, T. W.; Litke, K. E.; McIntyre, J. I.; Miley, H. S.; Schulte, S. M.; Smart, J. E.; Warren, G. A.

2007-08-01

High-purity copper is an attractive material for constructing ultra-low-background radiation measurement devices. Many low-background experiments using high-purity copper have indicated surface contamination emerges as the dominant background. Radon daughters plate out on exposed surfaces, leaving a residual 210Pb background that is difficult to avoid. Dust is also a problem; even under cleanroom conditions, the amount of U and Th deposited on surfaces can represent the largest remaining background. To control these backgrounds, a copper cleaning chemistry has been developed. Designed to replace an effective, but overly aggressive concentrated nitric acid etch, this peroxide-based solution allows for a more controlled cleaning of surfaces. The acidified hydrogen peroxide solution will generally target the Cu +/Cu 2+ species which are the predominant surface participants, leaving the bulk of copper metal intact. This preserves the critical tolerances of parts and eliminates significant waste disposal issues. Accompanying passivation chemistry has also been developed that protects copper surfaces from oxidation. Using a high-activity polonium surface spike, the most difficult-to-remove daughter isotope of radon, the performance of these methods are quantified.

Mechanisms of Contact-Mediated Killing of Yeast Cells on Dry Metallic Copper Surfaces▿

PubMed Central

Quaranta, Davide; Krans, Travis; Santo, Christophe Espírito; Elowsky, Christian G.; Domaille, Dylan W.; Chang, Christopher J.; Grass, Gregor

2011-01-01

Surfaces made of copper or its alloys have strong antimicrobial properties against a wide variety of microorganisms. However, the molecular mode of action responsible for the antimicrobial efficacy of metallic copper is not known. Here, we show that dry copper surfaces inactivate Candida albicans and Saccharomyces cerevisiae within minutes in a process called contact-mediated killing. Cellular copper ion homeostasis systems influenced the kinetics of contact-mediated killing in both organisms. Deregulated copper ion uptake through a hyperactive S. cerevisiae Ctr1p (ScCtr1p) copper uptake transporter in Saccharomyces resulted in faster inactivation of mutant cells than of wild-type cells. Similarly, lack of the C. albicans Crp1p (CaCrp1p) copper-efflux P-type ATPase or the metallothionein CaCup1p caused more-rapid killing of Candida mutant cells than of wild-type cells. Candida and Saccharomyces took up large quantities of copper ions as soon as they were in contact with copper surfaces, as indicated by inductively coupled plasma mass spectroscopy (ICP-MS) analysis and by the intracellular copper ion-reporting dye coppersensor-1. Exposure to metallic copper did not cause lethality through genotoxicity, deleterious action on a cell's genetic material, as indicated by a mutation assay with Saccharomyces. Instead, toxicity mediated by metallic copper surfaces targeted membranes in both yeast species. With the use of Live/Dead staining, onset of rapid and extensive cytoplasmic membrane damage was observed in cells from copper surfaces. Fluorescence microscopy using the indicator dye DiSBaC2(3) indicated that cell membranes were depolarized. Also, during contact-mediated killing, vacuoles first became enlarged and then disappeared from the cells. Lastly, in metallic copper-stressed yeasts, oxidative stress in the cytoplasm and in mitochondria was elevated. PMID:21097600

The Underpotential Deposition of Copper on Pt(311): Site Selective Deposition and Anion Effects

DTIC Science & Technology

1994-03-14

water (18 MOhms Millipore Milli-Q water). Aqueous acid solutions were prepared from high-purity (ULTREX) sulfuric acid . Copper ion solutions were...prepared by dissolution of CuSO 4 .5H 2 0 (Aldrich Gold Label 5N5) in sulfuric acid solutions. Chloride and bromide containing solutions were prepared by...Voltammetric characteristics of a Pt(311) electrode in acidic solutions containing chloride and bromide. Fig. 1 shows cyclic voltammograxns for the

Mechanisms of Corrosion of Copper-Nickel Alloys in Sulfide-Polluted Seawater

DTIC Science & Technology

1981-02-01

anaerobic bacteria, which convert the natural sulfate content of the seawater into sulfides. Also, the putrefaction of organic compounds containing...corrosion rate bozause the Cu2 0 growth3 292 probably follows a parabolic rate law. The corrosion behavior at high oxygen concentrations (> 7.0 g/m ) is...determined using the rotating ring disk electrode method or SRI’s recently developed rotating cylinder- collector electrode.3 In these methods, the

Critical review: Copper runoff from outdoor copper surfaces at atmospheric conditions.

PubMed

Hedberg, Yolanda S; Hedberg, Jonas F; Herting, Gunilla; Goidanich, Sara; Odnevall Wallinder, Inger

2014-01-01

This review on copper runoff dispersed from unsheltered naturally patinated copper used for roofing and facades summarizes and discusses influencing factors, available literature, and predictive models, and the importance of fate and speciation for environmental risk assessment. Copper runoff from outdoor surfaces is predominantly governed by electrochemical and chemical reactions and is highly dependent on given exposure conditions (size, inclination, geometry, degree of sheltering, and orientation), surface parameters (age, patina composition, and thickness), and site-specific environmental conditions (gaseous pollutants, chlorides, rainfall characteristics (amount, intensity, pH), wind direction, temperature, time of wetness, season). The corrosion rate cannot be used to assess the runoff rate. The extent of released copper varies largely between different rain events and is related to dry and wet periods, dry deposition prior to the rain event and prevailing rain and patina characteristics. Interpretation and use of copper runoff data for environmental risk assessment and management need therefore to consider site-specific factors and focus on average data of long-term studies (several years). Risk assessments require furthermore that changes in copper speciation, bioavailability aspects, and potential irreversible retention on solid surfaces are considered, factors that determine the environmental fate of copper runoff from outdoor surfaces.

Solvent polarity effect on quality of n-octadecanethiol self-assembled monolayers on copper and oxidized copper

NASA Astrophysics Data System (ADS)

Zhang, Yaozhong; Zhou, Jun; Zhang, Xiaoli; Hu, Jun; Gao, Han

2014-11-01

This article reports the effect of solvent polarity on the formation of n-octadecanethiol self-assembled monolayers (C18SH-SAMs) on pure copper surface and oxidized copper surface. The quality of SAMs prepared in different solvents (n-hexane, toluene, trichloroethylene, chloroform, acetone, acetonitrile, ethanol) was monitored by EIS, RAIRS and XPS. The results indicated that C18SH-SAMs formed in these solvents were in good barrier properties on pure copper surface and the structures of monolayers formed in high polarity solvents were more compact and orderly than that formed in low polarity solvents. For comparison, C18SH adsorbed on the surface of oxidized copper in these solvents were studied and the results indicated that C18SH could be adsorbed on oxidized copper surface after the reduction of copper oxide layer by thiols. Compared with high polarity solvents, a limited reduction process of oxidized copper by thiols led to the incompletely formation of monolayers in low polarity solvents. This can be interpreted that the generated water on solid-liquid interface and a smaller reaction force restrict the continuous reduction reaction in low polarity solvents

The polymeric nanofilm of triazinedithiolsilane fabricated by self-assembled technique on copper surface. Part 2: Characterization of composition and morphology

NASA Astrophysics Data System (ADS)

Wang, Yabin; Liu, Zhong; Huang, Yudong; Qi, Yutai

2015-11-01

In the first part, a novel design route for metal protection against corrosion was proposed, and a class of triazinedithiolsilane compounds was conceived as protector for copper. The protective capability of the polymeric nanofilm, fabricated by self-assembling one representative (abbreviated as TESPA) of triazinedithiolsilane compounds onto copper surface, has been investigated and evaluated by electrochemical tests. The results show that the polymeric nanofilm significantly inhibits copper corrosion. This study, on the one hand, concentrates on the chemical composition of the TESPA polymeric nanofilm by means of X-ray photoelectron spectroscopy (XPS). The XPS results reveal that the chemical bonds between copper and TESPA monomers, three dimensional disulfide units and siloxane networks are responsible for the satisfactory protection of TESPA polymeric nanofilm against copper corrosion. On the other hand, scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) are utilized to reveal the morphology and the uniformity of the TESPA polymeric nanofilm. The SEM-EDS results demonstrate that the copper surfaces are uniformly covered with TESPA self-assembled monolayer and the polymeric nanofilm. The TESPA-covered copper surfaces turn out to be smoother than that of the bare copper surface.

A study of the effects of phosphates on copper corrosion in drinking water: Copper release, electrochemical, and surface analysis approach

NASA Astrophysics Data System (ADS)

Kang, Young C.

The following work is the study to evaluate the impact of corrosion inhibitors on the copper metal in drinking water and to investigate the corrosion mechanism in the presence and absence of inhibitors. Electrochemical experiments were conducted to understand the effect of specific corrosion inhibitors in synthetic drinking water which was prepared with controlled specific water quality parameters. Water chemistry was studied by Inductively Coupled Plasma--Atomic Emission Spectroscopy (ICP--AES) to investigate the copper leaching rate with time. Surface morphology, crystallinity of corrosion products, copper oxidation status, and surface composition were characterized by various solid surface analysis methods, such as Scanning Electron Microscopy/Energy--Dispersive Spectrometry (SEM/EDS), Grazing-Incidence-angle X-ray Diffraction (GIXRD), X-ray Photoelectron Spectroscopy (XPS), and Time-of-Flight Secondary Ions Mass Spectrometry (ToF-SIMS). The purpose of the first set of experiments was to test various electrochemical techniques for copper corrosion for short term before studying a long term loop system. Surface analysis techniques were carried out to identify and study the corrosion products that form on the fresh copper metal surface when copper coupons were exposed to test solutions for 2 days of experiments time. The second phase of experiments was conducted with a copper pipe loop system in a synthetic tap water over an extended period of time, i.e., 4 months. Copper release and electrochemically measured corrosion activity profiles were monitored carefully with and without corrosion inhibitor, polyphosphate. A correlation between the copper released into the solution and the electrochemically measured corrosion activities was also attempted. To investigate corrosion products on the copper pipe samples, various surface analysis techniques were applied in this study. Especially, static mass spectra acquisition and element distribution mapping were carried out by ToF-SIMS. Dynamic SIMS provided shallow depth profile of corroded copper sample. The third set of the experiments was related to electrochemical noise (EN) measurement through copper coupons to pipes. Calculating corrosion rate of a metal and predicting exactly how long it lasts are problematic since the metal corrosion may be caused by combined corrosion types. Many other metals undergo not only uniform corrosion, but localized corrosion. Uniform corrosion may be conducive for copper pipe to prevent it from further severe corrosion and form passivated film, but localized corrosion causes pinhole leaks and limits the copper pipe applications. The objective of this set of experiment is to discuss the application of electrochemical noise approaches to drinking water copper corrosion problems. Specially, a fundamental description of EN is presented including a discussion of how to interpret the results and technique limitations. Although it was indicated with electrochemical analysis that the corrosion activity was affected by orthophosphate addition in the short-term test, no copper-phosphate complex or compound was found by copper surface characterization. Apparently, orthophosphate can inhibit corrosion by adsorption on the copper surface, but cannot form solid complexes with copper in such a short time, 2 days. When polyphosphate was added into recirculating copper pipe system, copper level increased and polarization resistance decreased. Greenish blue residue on the copper pipe was suspected as copper phosphate complex and corrosion inhibition mechanism was proposed.

Modification of surface properties of copper-refractory metal alloys

DOEpatents

Verhoeven, John D.; Gibson, Edwin D.

1993-10-12

The surface properties of copper-refractory metal (CU-RF) alloy bodies are modified by heat treatments which cause the refractory metal to form a coating on the exterior surfaces of the alloy body. The alloys have a copper matrix with particles or dendrites of the refractory metal dispersed therein, which may be niobium, vanadium, tantalum, chromium, molybdenum, or tungsten. The surface properties of the bodies are changed from those of copper to that of the refractory metal.

Active screen cage pulsed dc discharge for implanting copper in polytetrafluoroethylene (PTFE)

NASA Astrophysics Data System (ADS)

Zaka-ul-Islam, Mujahid; Naeem, Muhammad; Shafiq, Muhammad; Sitara; Jabbar Al-Rajab, Abdul; Zakaullah, Muhammad

2017-07-01

Polymers such as polytetrafluoroethylene (PTFE) are widely used in artificial organs where long-term anti-bacterial properties are required to avoid bacterial proliferation. Copper or silver ion implantation on the polymer surface is known as a viable method to generate long-term anti-bacterial properties. Here, we have tested pulsed DC plasma with copper cathodic cage for the PTFE surface treatment. The surface analysis of the treated specimens suggests that the surface, structural properties, crystallinity and chemical structure of the PTFE have been changed, after the plasma treatment. The copper release tests show that copper ions are released from the polymer at a slow rate and quantity of the released copper increases with the plasma treatment time.

Modeling MIC copper release from drinking water pipes.

PubMed

Pizarro, Gonzalo E; Vargas, Ignacio T; Pastén, Pablo A; Calle, Gustavo R

2014-06-01

Copper is used for household drinking water distribution systems given its physical and chemical properties that make it resistant to corrosion. However, there is evidence that, under certain conditions, it can corrode and release unsafe concentrations of copper to the water. Research on drinking water copper pipes has developed conceptual models that include several physical-chemical mechanisms. Nevertheless, there is still a necessity for the development of mathematical models of this phenomenon, which consider the interaction among physical-chemical processes at different spatial scales. We developed a conceptual and a mathematical model that reproduces the main processes in copper release from copper pipes subject to stagnation and flow cycles, and corrosion is associated with biofilm growth on the surface of the pipes. We discuss the influence of the reactive surface and the copper release curves observed. The modeling and experimental observations indicated that after 10h stagnation, the main concentration of copper is located close to the surface of the pipe. This copper is associated with the reactive surface, which acts as a reservoir of labile copper. Thus, for pipes with the presence of biofilm the complexation of copper with the biomass and the hydrodynamics are the main mechanisms for copper release. Copyright © 2013 Elsevier B.V. All rights reserved.

Improvement of MRR and surface roughness during electrical discharge machining (EDM) using aluminum oxide powder mixed dielectric fluid

NASA Astrophysics Data System (ADS)

Khan, A. A.; Mohiuddin, A. K. M.; Latif, M. A. A.

2018-01-01

This paper discusses the effect of aluminium oxide (Al203) addition to dielectric fluid during electrical discharge machining (EDM). Aluminium oxide was added to the dielectric used in the EDM process to improve its performance when machining the stainless steel AISI 304, while copper was used as the electrode. Effect of the concentration of Al203 (0.3 mg/L) in dielectric fluid was compared with EDM without any addition of Al203. Surface quality of stainless steel and the material removal rate were investigated. Design of the experiment (DOE) was used for the experimental plan. Statistical analysis was done using ANOVA and then appropriate model was designated. The experimental results show that with dispersing of aluminium oxide in dielectric fluid surface roughness was improved while the material removal rate (MRR) was increased to some extent. These indicate the improvement of EDM performance using aluminium oxide in dielectric fluid. It was also found that with increase in pulse on time both MRR and surface roughness increase sharply.

Membrane Lipid Peroxidation in Copper Alloy-Mediated Contact Killing of Escherichia coli

PubMed Central

Hong, Robert; Kang, Tae Y.; Michels, Corinne A.

2012-01-01

Copper alloy surfaces are passive antimicrobial sanitizing agents that kill bacteria, fungi, and some viruses. Studies of the mechanism of contact killing in Escherichia coli implicate the membrane as the target, yet the specific component and underlying biochemistry remain unknown. This study explores the hypothesis that nonenzymatic peroxidation of membrane phospholipids is responsible for copper alloy-mediated surface killing. Lipid peroxidation was monitored with the thiobarbituric acid-reactive substances (TBARS) assay. Survival, TBARS levels, and DNA degradation were followed in cells exposed to copper alloy surfaces containing 60 to 99.90% copper or in medium containing CuSO4. In all cases, TBARS levels increased with copper exposure levels. Cells exposed to the highest copper content alloys, C11000 and C24000, exhibited novel characteristics. TBARS increased immediately at a very rapid rate but peaked at about 30 min. This peak was associated with the period of most rapid killing, loss in membrane integrity, and DNA degradation. DNA degradation is not the primary cause of copper-mediated surface killing. Cells exposed to the 60% copper alloy for 60 min had fully intact genomic DNA but no viable cells. In a fabR mutant strain with increased levels of unsaturated fatty acids, sensitivity to copper alloy surface-mediated killing increased, TBARS levels peaked earlier, and genomic DNA degradation occurred sooner than in the isogenic parental strain. Taken together, these results suggest that copper alloy surface-mediated killing of E. coli is triggered by nonenzymatic oxidative damage of membrane phospholipids that ultimately results in the loss of membrane integrity and cell death. PMID:22247141

Electroactivity of Phototrophic River Biofilms and Constitutive Cultivable Bacteria ▿ †

PubMed Central

Lyautey, Emilie; Cournet, Amandine; Morin, Soizic; Boulêtreau, Stéphanie; Etcheverry, Luc; Charcosset, Jean-Yves; Delmas, François; Bergel, Alain; Garabetian, Frédéric

2011-01-01

Electroactivity is a property of microorganisms assembled in biofilms that has been highlighted in a variety of environments. This characteristic was assessed for phototrophic river biofilms at the community scale and at the bacterial population scale. At the community scale, electroactivity was evaluated on stainless steel and copper alloy coupons used both as biofilm colonization supports and as working electrodes. At the population scale, the ability of environmental bacterial strains to catalyze oxygen reduction was assessed by cyclic voltammetry. Our data demonstrate that phototrophic river biofilm development on the electrodes, measured by dry mass and chlorophyll a content, resulted in significant increases of the recorded potentials, with potentials of up to +120 mV/saturated calomel electrode (SCE) on stainless steel electrodes and +60 mV/SCE on copper electrodes. Thirty-two bacterial strains isolated from natural phototrophic river biofilms were tested by cyclic voltammetry. Twenty-five were able to catalyze oxygen reduction, with shifts of potential ranging from 0.06 to 0.23 V, cathodic peak potentials ranging from −0.36 to −0.76 V/SCE, and peak amplitudes ranging from −9.5 to −19.4 μA. These isolates were diversified phylogenetically (Actinobacteria, Firmicutes, Bacteroidetes, and Alpha-, Beta-, and Gammaproteobacteria) and exhibited various phenotypic properties (Gram stain, oxidase, and catalase characteristics). These data suggest that phototrophic river biofilm communities and/or most of their constitutive bacterial populations present the ability to promote electronic exchange with a metallic electrode, supporting the following possibilities: (i) development of electrochemistry-based sensors allowing in situ phototrophic river biofilm detection and (ii) production of microbial fuel cell inocula under oligotrophic conditions. PMID:21642402

Cyclically optimized electrochemical processes

NASA Astrophysics Data System (ADS)

Ruedisueli, Robert Louis

It has been frequently observed in experiment and industry practice that electrochemical processes (deposition, dissolution, fuel cells) operated in an intermittent or cyclic (AC) mode show improvements in efficiency and/or quality and yield over their steady (DC) mode of operation. Whether rationally invoked by design or empirically tuned-in, the optimal operating frequency and duty cycle is dependent upon the dominant relaxation time constant for the process in question. The electrochemical relaxation time constant is a function of: double-layer and reaction intermediary pseudo-capacitances, ion (charge) transport via electrical migration (mobility), and diffusion across a concentration gradient to electrode surface reaction sites where charge transfer and species incorporation or elimination occurs. The rate determining step dominates the time constant for the reaction or process. Electrochemical impedance spectroscopy (EIS) and piezoelectric crystal electrode (PCE) response analysis have proven to be useful tools in the study and identification of reaction mechanisms. This work explains and demonstrates with the electro-deposition of copper the application of EIS and PCE measurement and analysis to the selection of an optimum cyclic operating schedule, an optimum driving frequency for efficient, sustained cyclic (pulsed) operation.

Anodic stripping voltammetry with carbon paste electrodes for rapid Ag(I) and Cu(II) determinations.

PubMed

Labar, C; Lamberts, L

1997-05-01

The simultaneous determination of silver(I) and copper(II) is realized for the routine analysis of trace levels of these elements by anodic stripping voltammetry (ASV) at the carbon paste electrode (CPE). The electrochemical response is studied in 14 different supporting electrolytes, ranging from acidic solutions (pH 0.1) to neutral and basic (pH 9.7) media, and the parameters governing electrodeposition and stripping steps are characterized for each medium by the use of pseudo-voltammograms. Comparison between different modes of matter transport mechanisms is also given. The dynamic range of the method is 0.05 to 150 mug 1(-1) Ag(I) in the majority of the media studied and can be extended to 400 mug l(-1) in selected media, with a general reproducibility in the +/- 2% range for five replicate measurements. The total analysis time lies between approximately 30 s and 10 min. Activation of the CPE surface has been studied, but this pretreatment is demonstrated to be unfavourable and is replaced by a simpler unique 'cleaning' procedure of dipping the CPE in diluted nitric acid.

Effects of electrode surface structure on the mechanoelectrical transduction of IPMC sensors

NASA Astrophysics Data System (ADS)

Palmre, Viljar; Pugal, David; Kim, Kwang

2014-03-01

This study investigates the effects of electrode surface structure on the mechanoelectrical transduction of IPMC sensors. A physics-based mechanoelectrical transduction model was developed that takes into account the electrode surface profile (shape) by describing the polymer-electrode interface as a Koch fractal structure. Based on the model, the electrode surface effects were experimentally investigated in case of IPMCs with Pd-Pt electrodes. IPMCs with different electrode surface structures were fabricated through electroless plating process by appropriately controlling the synthesis parameters and conditions. The changes in the electrode surface morphology and the corresponding effects on the IPMC mechanoelectrical transduction were examined. Our experimental results indicate that increasing the dispersion of Pd particles near the membrane surface, and thus the polymer-electrode interfacial area, leads to a higher peak mechanoelectrically induced voltage of IPMC. However, the overall effect of the electrode surface structure is relatively low compared to the electromechanical transduction, which is in good agreement with theoretical prediction.

Method For Creating Corrosion Resistant Surface On An Aluminum Copper Alloy

DOEpatents

Mansfeld, Florian B.; Wang, You; Lin, Simon H.

1997-06-03

A method for treating the surface of aluminum alloys hang a relatively high copper content is provided which includes the steps of removing substantially all of the copper from the surface, contacting the surface with a first solution containing cerium, electrically charging the surface while contacting the surface in an aqueous molybdate solution, and contacting the surface with a second solution containing cerium. The copper is substantially removed from the surface in the first step either by (i) contacting the surface with an acidic chromate solution or by (ii) contacting the surface with an acidic nitrate solution while subjecting the surface to an electric potential. The corrosion-resistant surface resulting from the invention is excellent, consistent and uniform throughout the surface. Surfaces treated by the invention may often be certified for use in salt-water services.

Copper plasmonics and catalysis: role of electron-phonon interactions in dephasing localized surface plasmons

NASA Astrophysics Data System (ADS)

Sun, Qi-C.; Ding, Yuchen; Goodman, Samuel M.; H. Funke, Hans; Nagpal, Prashant

2014-10-01

Copper metal can provide an important alternative for the development of efficient, low-cost and low-loss plasmonic nanoparticles, and selective nanocatalysts. However, poor chemical stability and lack of insight into photophysics and plasmon decay mechanisms has impeded study. Here, we use smooth conformal ALD coating on copper nanoparticles to prevent surface oxidation, and study dephasing time for localized surface plasmons on different sized copper nanoparticles. Using dephasing time as a figure of merit, we elucidate the role of electron-electron, electron-phonon, impurity, surface and grain boundary scattering on the decay of localized surface plasmon waves. Using our quantitative analysis and different temperature dependent measurements, we show that electron-phonon interactions dominate over other scattering mechanisms in dephasing plasmon waves. While interband transitions in copper metal contributes substantially to plasmon losses, tuning surface plasmon modes to infrared frequencies leads to a five-fold enhancement in the quality factor. These findings demonstrate that conformal ALD coatings can improve the chemical stability for copper nanoparticles, even at high temperatures (>300 °C) in ambient atmosphere, and nanoscaled copper is a good alternative material for many potential applications in nanophotonics, plasmonics, catalysis and nanoscale electronics.Copper metal can provide an important alternative for the development of efficient, low-cost and low-loss plasmonic nanoparticles, and selective nanocatalysts. However, poor chemical stability and lack of insight into photophysics and plasmon decay mechanisms has impeded study. Here, we use smooth conformal ALD coating on copper nanoparticles to prevent surface oxidation, and study dephasing time for localized surface plasmons on different sized copper nanoparticles. Using dephasing time as a figure of merit, we elucidate the role of electron-electron, electron-phonon, impurity, surface and grain boundary scattering on the decay of localized surface plasmon waves. Using our quantitative analysis and different temperature dependent measurements, we show that electron-phonon interactions dominate over other scattering mechanisms in dephasing plasmon waves. While interband transitions in copper metal contributes substantially to plasmon losses, tuning surface plasmon modes to infrared frequencies leads to a five-fold enhancement in the quality factor. These findings demonstrate that conformal ALD coatings can improve the chemical stability for copper nanoparticles, even at high temperatures (>300 °C) in ambient atmosphere, and nanoscaled copper is a good alternative material for many potential applications in nanophotonics, plasmonics, catalysis and nanoscale electronics. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04719b

Method for forming a potential hydrocarbon sensor with low sensitivity to methane and CO

DOEpatents

Mukundan, Rangachary; Brosha, Eric L.; Garzon, Fernando

2003-12-02

A hydrocarbon sensor is formed with an electrolyte body having a first electrolyte surface with a reference electrode depending therefrom and a metal oxide electrode body contained within the electrolyte body and having a first electrode surface coplanar with the first electrolyte surface. The sensor was formed by forming a sintered metal-oxide electrode body and placing the metal-oxide electrode body within an electrolyte powder. The electrolyte powder with the metal-oxide electrode body was pressed to form a pressed electrolyte body containing the metal-oxide electrode body. The electrolyte was removed from an electrolyte surface above the metal-oxide electrode body to expose a metal-oxide electrode surface that is coplanar with the electrolyte surface. The electrolyte body and the metal-oxide electrode body were then sintered to form the hydrocarbon sensor.

Electrochemical characterization of corrosion in materials of grounding systems, simulating conditions of synthetic soils with characteristics of local soils

NASA Astrophysics Data System (ADS)

Salas, Y.; Guerrero, L.; Vera-Monroy, S. P.; Blanco, J.; Jimenez, C.

2017-12-01

The integrity of structures buried in earthing becomes relevant when analysing maintenance and replacement costs of these systems, as the deterioration is mainly due to two factors, namely: the failures caused in the electrical systems, which are due to the system. Failure in earthing due to corrosion at the interface cause an alteration in the structure of the component material and generates an undesirable resistivity that cause malfunction in this type of protection systems. Two local soils were chosen that were categorized as sandy loam and clay loam type, whose chemical characteristics were simulated by means of an electrolyte corresponding to the amount of ions present determined by a soil characterization based on the CICE (effective cation exchange coefficient), which allows us to deduce the percentage of chloride and sulphate ions present for the different levels established in the experimental matrix. The interaction of these soils with grounding electrodes is a complex problem involving many factors to consider. In this study, the rates and corrosion currents of the different soils on two types of electrodes, one copper and the other AISI 304 stainless steel, were approximated by electrochemical techniques such as potentiodynamic curves and electrochemical impedance spectra. Considerably higher speeds were determined for copper-type electrodes when compared to those based on steel. However, from the Nyquist diagrams, it was noted that copper electrodes have better electrical performance than steel ones. The soil with the highest ionic activity turned out to be the sandy loam. The clay loam soil presents a tendency to water retention and this may be the reason for the different behaviour with respect to ionic mobility. The diffusion control in the steel seems to alter the ionic mobility because its corrosion rates proved to be very similar regardless of the type of soil chemistry. In general, corrosion rates fell since tenths of a millimetre every year to the hundredths of a millimetre in the case of the steel-based electrode, which are relatively small corrosion rates.

Copper Reduction and Contact Killing of Bacteria by Iron Surfaces

PubMed Central

Mathews, Salima; Kumar, Ranjeet

2015-01-01

The well-established killing of bacteria by copper surfaces, also called contact killing, is currently believed to be a combined effect of bacterial contact with the copper surface and the dissolution of copper, resulting in lethal bacterial damage. Iron can similarly be released in ionic form from iron surfaces and would thus be expected to also exhibit contact killing, although essentially no contact killing is observed by iron surfaces. However, we show here that the exposure of bacteria to iron surfaces in the presence of copper ions results in efficient contact killing. The process involves reduction of Cu2+ to Cu+ by iron; Cu+ has been shown to be considerably more toxic to cells than Cu2+. The specific Cu+ chelator, bicinchoninic acid, suppresses contact killing by chelating the Cu+ ions. These findings underline the importance of Cu+ ions in the contact killing process and infer that iron-based alloys containing copper could provide novel antimicrobial materials. PMID:26150470

Large-scale fabrication of single crystalline tin nanowire arrays.

PubMed

Luo, Bin; Yang, Dachi; Liang, Minghui; Zhi, Linjie

2010-09-01

Large-scale single crystalline tin nanowire arrays with preferred lattice orientation along the [100] direction were fabricated in porous anodic aluminium oxide (AAO) membranes by the electrodeposition method using copper nanorod as a second electrode.

Surface modifications of chalcopyrite CuInS2 thin films for photochatodes in photoelectrochemical water splitting under sunlight irradiation

NASA Astrophysics Data System (ADS)

Gunawan; Haris, A.; Widiyandari, H.; Septina, W.; Ikeda, S.

2017-02-01

Copper chalcopyrite semiconductors include a wide range of compounds that are of interest for photoelectrochemical water splitting which enables them to be used as photochatodes for H2 generation. Among them, CuInS2 is one of the most important materials due to its optimum band gap energy for sunlight absorption. In the present study, we investigated the application of CuInS2 fabricated by electrodeposition as photochatodes for water splitting. Thin film of CuInS2 chalcopyrite was formed on Mo-coated glass substrate by stacked electrodeposition of copper and indium followed by sulfurization under H2S flow. The films worked as a H2 liberation electrode under cathodic polarization from a solution containing Na2SO4 after loading Pt deposits on the film. Introduction of an n-type CdS layer by chemical bath deposition on the CuInS2 surface before the Pt loading resulted appreciable improvements of H2 liberation efficiency and a higher photocurrent onset potential. Moreover, the use of In2S3 layer as an alternative n-type layer to the CdS significantly improved the H2 liberation performance: the CuInS2 film modified with In2S3 and Pt deposits worked as an efficient photocathode for photoelectrochemical water splitting.

Cermet anode compositions with high content alloy phase

DOEpatents

Marschman, Steven C.; Davis, Norman C.

1989-01-01

Cermet electrode compositions comprising NiO-NiFe.sub.2 O.sub.4 -Cu-Ni, and methods for making, are disclosed. Addition of nickel metal prior to formation and densification of a base mixture into the cermet allows for an increase in the total amount of copper and nickel that can be contained in the NiO-NiFe.sub.2 O.sub.4 oxide system. Nickel is present in a base mixture weight concentration of from 0.1% to 10%. Copper is present in the alloy phase in a weight concentration of from 10% to 30% of the densified composition. Such cermet electrodes can be formed to have electrical conductivities well in excess of 100 ohm.sup.-1 cm.sup.-1. Other alloy and oxide system cermets having high content metal phases are also expected to be manufacturable in accordance with the invention.

Cermet anode compositions with high content alloy phase

DOEpatents

Marschman, S.C.; Davis, N.C.

1989-10-03

Cermet electrode compositions comprising NiO-NiFe[sub 2]O[sub 4]-Cu-Ni, and methods for making, are disclosed. Addition of nickel metal prior to formation and densification of a base mixture into the cermet allows for an increase in the total amount of copper and nickel that can be contained in the NiO-NiFe[sub 2]O[sub 4] oxide system. Nickel is present in a base mixture weight concentration of from 0.1% to 10%. Copper is present in the alloy phase in a weight concentration of from 10% to 30% of the densified composition. Such cermet electrodes can be formed to have electrical conductivities well in excess of 100 ohm[sup [minus]1] cm[sup [minus]1]. Other alloy and oxide system cermets having high content metal phases are also expected to be manufacturable in accordance with the invention.

Feedthrough terminal for high-power cell

DOEpatents

Kaun, T.D.

1982-05-28

A feedthrough terminal for a high power electrochemical storage cell providing low resistance coupling to the conductive elements therein while isolating the terminal electrode from the highly corrosive environment within the cell is disclosed. A large diameter, cylindrical copper electrode is enclosed in a stainless steel tube with a BN powder feedthrough seal maintained around the stainless steel tube by means of facing insulative bushings and an outer sleeve. One end of the copper conductor is silver-brazed directly to a flat, butterfly bus bar within the cell, with the adjacent end of the surrounding outer feedthrough sleeve welded to the bus bar. A threaded seal is fixedly positioned on a distal portion of the stainless steel tube immediately adjacent the distal insulative bushing so as to compress the feedthrough seal in tight fitting relation around the stainless steel tube in providing a rugged, leak-proof electrical feedthrough terminal for the power cell.

Observation of copper atoms behavior in a vacuum arc discharge using laser spectroscopy

NASA Astrophysics Data System (ADS)

Sung, Y. M.; Hayashi, Y.; Okraku-Yirenkyi, Y.; Otsubo, M.; Honda, C.; Sakoda, T.

2003-01-01

In order to investigate the most important parameters influencing the breaking characteristic of a vacuum circuit breaker (VCB), the behavior of copper (Cu) particles emitted from electrodes designed as an imitation of a vacuum valve of the VCB was observed. The temporal-spatial intensity distributions due to Cu particles in an excited state or a neutral state were measured using the laser induced fluorescence (LIF) technique and a charge coupled device camera attached with a special filter. The diffusion velocity of a Cu atom was also investigated by evaluating a Doppler shift of the LIF signal. The results showed that most Cu particles were emitted from the anode and were in an excited state or an ionized state during an arc discharge. Also, Cu particles were distributed between electrodes even after the discharge chocked, and its diffusion velocity in the direction of the cathode from the anode was about 2.6 km/s.

Innovative Electrostatic Adhesion Technologies

NASA Technical Reports Server (NTRS)

Bryan, Tom; Macleod, Todd; Gagliano, Larry; Williams, Scott; McCoy, Brian

2015-01-01

Developing specialized Electro-Static grippers (commercially used in Semiconductor Manufacturing and in package handling) will allow gentle and secure Capture, Soft Docking, and Handling of a wide variety of materials and shapes (such as upper-stages, satellites, arrays, and possibly asteroids) without requiring physical features or cavities for a pincher or probe or using harpoons or nets. Combined with new rigid boom mechanisms or small agile chaser vehicles, flexible, high speed Electro-Static Grippers can enable compliant capture of spinning objects starting from a safe stand-off distance. Electroadhesion (EA) can enable lightweight, ultra-low-power, compliant attachment in space by using an electrostatic force to adhere similar and dissimilar surfaces. A typical EA enabled device is composed of compliant space-rated materials, such as copper-clad polyimide encapsulated by polymers. Attachment is induced by strong electrostatic forces between any substrate material, such as an exterior satellite panel and a compliant EA gripper pad surface. When alternate positive and negative charges are induced in adjacent planar electrodes in an EA surface, the electric fields set up opposite charges on the substrate and cause an electrostatic adhesion between the electrodes and the induced charges on the substrate. Since the electrodes and the polymer are compliant and can conform to uneven or rough surfaces, the electrodes can remain intimately close to the entire surface, enabling high clamping pressures. Clamping pressures of more than 3 N/cm2 in shear can be achieved on a variety of substrates with ultra-low holding power consumption (measured values are less than 20 microW/Newton weight held). A single EA surface geometry can be used to clamp both dielectric and conductive substrates, with slightly different physical mechanisms. Furthermore EA clamping requires no normal force be placed on the substrate, as conventional docking requires. Internally funded research and development has demonstrated that EA can function effectively in space, even in the presence of strong ultraviolet radiation, atomic oxygen, and free electrons. We created a test setup in an existing vacuum chamber to simulate low-Earth-orbit conditions. An EA mechanism was fabricated and installed in the chamber, instrumented, operated in a vacuum, and subjected to ultraviolet photons and free electrons generated by an in-chamber multipactor electron emitter. Extensions to EA that can add value include proximity and contact sensing and transverse motion or rotation, both of which could enhance docking or assembly applications. Possible next steps include development of targeted applications for ground investigation or on-orbit subsystem performance demonstrations using low cost access to space such as CubeSats.

Innovative Electrostatic Adhesion Technologies

NASA Astrophysics Data System (ADS)

Gagliano, L.; Bryan, T.; Williams, S.; McCoy, B.; MacLeod, T.

Developing specialized Electro-Static grippers (commercially used in Semiconductor Manufacturing and in package handling) will allow gentle and secure Capture, Soft Docking, and Handling of a wide variety of materials and shapes (such as upper-stages, satellites, arrays, and possibly asteroids) without requiring physical features or cavities for a pincher or probe or using harpoons or nets. Combined with new rigid boom mechanisms or small agile chaser vehicles, flexible, high speed Electro-Static Grippers can enable compliant capture of spinning objects starting from a safe stand-off distance. Electroadhesion (EA) can enable lightweight, ultra-low-power, compliant attachment in space by using an electrostatic force to adhere similar and dissimilar surfaces. A typical EA enabled device is composed of compliant space-rated materials, such as copper-clad polyimide encapsulated by polymers. Attachment is induced by strong electrostatic forces between any substrate material, such as an exterior satellite panel and a compliant EA surface. When alternate positive and negative charges are induced in adjacent planar electrodes in an EA surface, the electric fields set up opposite charges on the substrate and cause an electrostatic adhesion between the electrodes and the induced charges on the substrate. Since the electrodes and the polymer are compliant and can conform to uneven or rough surfaces, the electrodes can remain intimately close to the entire surface, enabling high clamping pressures. Clamping pressures of more than 3 N/cm2 in shear can be achieved on a variety of substrates with ultra-low holding power consumption (measured values are less than 20 microW/Newton weight held). A single EA surface geometry can be used to clamp both dielectric and conductive substrates, with slightly different physical mechanisms. Furthermore EA clamping requires no normal force be placed on the substrate, as conventional docking requires. Internally funded research and development has demonstrated that EA can function effectively in space, even in the presence of strong ultraviolet radiation, atomic oxygen, and free electrons. We created a test setup in an existing vacuum chamber to simulate low-Earth-orbit conditions. An EA mechanism was fabricated and installed in the chamber, instrumented, operated in a vacuum, and subjected to ultraviolet photons and free electrons generated by an in-chamber multipactor electron emitter. Extensions to EA that can add value include proximity and contact sensing and transverse motion or rotation, both of which could enhance docking or assembly applications. Possible next steps include development of targeted applications for ground investigation or on-orbit subsystem performance demonstrations using low cost access to space such as CubeSats.

Cleaning and passivation of copper surfaces to remove surface radioactivity and prevent oxide formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoppe, Eric W.; Seifert, Allen; Aalseth, Craig E.

High-purity copper is an attractive material for constructing ultra-low-background radiation measurement devices. Many low-background experiments using high-purity copper have indicated surface contamination emerges as the dominant background. Radon daughters plate out on exposed surfaces, leaving a residual 210Pb background that is difficult to avoid. Dust is also a problem; even under cleanroom conditions, the amount of U and Th deposited on surfaces can represent the largest remaining background. To control these backgrounds, a copper cleaning chemistry has been developed. Designed to replace an effective, but overly aggressive concentrated nitric acid etch, this peroxide-based solution allows for a more controlled cleaningmore » of surfaces. The acidified hydrogen peroxide solution will generally target the Cu+/Cu2+ species which are the predominant surface participants, leaving the bulk of copper metal intact. This preserves the critical tolerances of parts and eliminates significant waste disposal issues. Accompanying passivation chemistry has also been developed that protects copper surfaces from oxidation. Using a high-activity polonium surface spike, the most difficult-to-remove daughter isotope of radon, the performance of these methods are quantified. © 2001 Elsevier Science. All rights reserved« less

Influence of nano-size inclusions on spall fracture of copper single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Razorenov, S. V.; Ivanchihina, G. E.; Kanel, G. I.

2007-12-12

Spall experiments have been carried out for copper in different structural states. The samples were copper single crystals, crystals of Cu+0.1% Si, copper crystals with silica particles of 180 nm average size, and polycrystalline copper. In experiments, the free surface velocity histories were recorded with the VISAR. The recovered samples were studied using optical microscopy and SEM. Solid solution Cu+0.1% Si demonstrates slower spall process than pure copper crystals. At longer pulse durations its spall strength is slightly less than that of pure crystals but approaches the latter with decreasing pulse duration. Fracture of copper with silica inclusions is completedmore » much faster. The spall strength of this material is close to that of Cu+0.1% Si crystals at longer pulse duration and approaches the strength of polycrystalline copper with decreasing the load duration. Fractography of the spall surfaces correlates with the free surface velocity histories. The main fracture surface of the Cu+0.1% Si grains consists of net of dimples {approx}4 {mu}m to 40 {mu}m mean diameter. The fracture surfaces of copper with silica inclusions is covered by a net of dimples of 1 {mu}m to 5 {mu}m size.« less

Secondary power-producing cell. [electrodes contain same two elements in different proportions

DOEpatents

Fischer, A.K.

1971-10-26

This cell consists of an anode and a cathode containing the same two elements in different proportions and an electrolyte which contains ions of the element which is to be transported through it. The electrodes consist of chromium, iron, lithium, sodium, cadmium, copper, or zinc and phosphorus, selenium, tellurium, sulfur, arsenic, or nitrogen. A method to heat the cathode in the regeneration cycle to transfer the electronegative component to the anode is provided. (RWR)

How to create ball lightning

NASA Technical Reports Server (NTRS)

Golka, Robert K., Jr.

1991-01-01

Procedures are given on how to produce ball lightning. Necessary equipment includes a transformer of 150,000 watts capable of providing approximately 10,000 amperes at 15 volts, 60 cycles; thick one inch cables of stranded wire leading into a 3 by 4 by 1 foot plastic tank; a quarter inch thick 4 by 6 inch aluminum plate to be used as one of the discharge electrodes; and another electrode of heavy copper wire with the insulation stripped back 6 inches.

Electrochemical studies of a truncated laccase produced in Pichia pastoris

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gelo-Pujic, M.; Kim, H.H.; Butlin, N.G.

1999-12-01

The cDNA that encodes an isoform is laccase from Trametes versicolor (LCCI), as well as a truncated version (LCCIa), was subcloned and expressed by using the yeast Pichia pastoris as the heterologous host. The amino acid sequence of LCCIa is identical to that of LCCI except that the final 11 amino acids at the C terminus of LCCI are replaced with a single cysteine residue. This modification was introduced for the purpose of improving the kinetics of electron transfer between an electrode and the copper-containing active site of laccase. The two laccases (LCCI and LCCIa) are compared in terms ofmore » their relative activity with two substrates that have different redox potentials. Results from electrochemical studies on solutions containing LCCI and LCCIa indicate that the redox potential of the active site of LCCIa is shifted to more negative values (411 mV versus normal hydrogen electrode voltage) than that found in other fungal laccases. In addition, replacing the 11 codons at the C terminus of the laccase gene with a single cysteine codon influences the rate of heterogeneous electron transfer between and electrode and the copper-containing active site. These results demonstrate for the first time that the rate of electron transfer between an oxidoreductase and an electrode can be enhanced by changes to the primary structure of a protein via site-directed mutagenesis.« less

Heat transfer from an oxidized large copper surface to liquid helium: Dependence on surface orientation and treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iwamoto, A.; Mito, T.; Takahata, K.

Heat transfer of large copper plates (18 x 76 mm) in liquid helium has been measured as a function of orientation and treatment of the heat transfer surface. The results relate to applications of large scale superconductors. In order to clarify the influence of the area where the surface treatment peels off, the authors studied five types of heat transfer surface areas including: (a) 100% polished copper sample, (b) and (c) two 50% oxidized copper samples having different patterns of oxidation, (d) 75% oxidized copper sample, (e) 90% oxidized copper sample, and (f) 100% oxidized copper sample. They observed thatmore » the critical heat flux depends on the heat transfer surface orientation. The critical heat flux is a maximum at angles of 0{degrees} - 30{degrees} and decreases monotonically with increasing angles above 30{degrees}, where the angle is taken in reference to the horizontal axis. On the other hand, the minimum heat flux is less dependent on the surface orientation. More than 75% oxidation on the surface makes the critical heat flux increase. The minimum heat fluxes of the 50 and 90% oxidized Cu samples approximately agree with that of the 100% oxidized Cu sample. Experiments and calculations show that the critical and the minimum heat fluxes are a bilinear function of the fraction of oxidized surface area.« less

Determination of an organic-acid analog of DOC for use in copper toxicity studies on salmonids

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacRae, R.K.; Meyer, J.S.; Hansen, J.A.

1995-12-31

Concentrations of dissolved copper in streams draining mine sites often exceed concentrations shown to cause acute and chronic mortality in salmonids. However, toxicity and impaired behaviors may be modified by dissolved organic carbon (DOC) and other inorganic components present in the site water. The effects of DOC on copper speciation, and thus bioavailability and toxicity, were determined by titrating stream waters with copper, using a cupric ion-specific electrode to detect free copper concentrations. Effects of various competing cations (e.g., Ca{sup +2}, Co{sup +2}) on copper-DOC binding were also evaluated. Titration results were evaluated using Scatchard and non-linear regression analyses tomore » quantify the strength and capacity of copper-DOC binding. Inorganic speciation was determined using the geochemical model MINEQL{sup +}. Results of these titrations indicated the presence of two or three distinct copper binding components in site water DOC. Three commercially available organic acids where then chosen to mimic the binding characteristics of natural DOC. This DOC-analog was used successfully in fish toxicity studies to evaluate the influence of DOC on copper bioavailability. Geochemical models were developed to predict copper speciation in both laboratory test waters and site waters, for any typical combination of water chemistry parameters (pH, alkalinity, [DOC], etc.). A combined interpretation of fish toxicity and modeling results indicate that some DOC-bound copper was bioavailable.« less

Ultraviolet corona detection sensor study

NASA Technical Reports Server (NTRS)

Schmitt, R. J.; MATHERN

1976-01-01

The feasibility of detecting electrical corona discharge phenomena in a space simulation chamber via emission of ultraviolet light was evaluated. A corona simulator, with a hemispherically capped point to plane electrode geometry, was used to generate corona glows over a wide range of pressure, voltage, current, electrode gap length and electrode point radius. Several ultraviolet detectors, including a copper cathode gas discharge tube and a UV enhanced silicon photodiode detector, were evaluated in the course of the spectral intensity measurements. The performance of both silicon target vidicons and silicon intensified target vidicons was evaluated analytically using the data generated by the spectroradiometer scans and the performance data supplied by the manufacturers.

Electrostatic dispersion lenses and ion beam dispersion methods

DOEpatents

Dahl, David A [Idaho Falls, ID; Appelhans, Anthony D [Idaho Falls, ID

2010-12-28

An EDL includes a case surface and at least one electrode surface. The EDL is configured to receive through the EDL a plurality of ion beams, to generate an electrostatic field between the one electrode surface and either the case surface or another electrode surface, and to increase the separation between the beams using the field. Other than an optional mid-plane intended to contain trajectories of the beams, the electrode surface or surfaces do not exhibit a plane of symmetry through which any beam received through the EDL must pass. In addition or in the alternative, the one electrode surface and either the case surface or the other electrode surface have geometries configured to shape the field to exhibit a less abrupt entrance and/or exit field transition in comparison to another electrostatic field shaped by two nested, one-quarter section, right cylindrical electrode surfaces with a constant gap width.

A hybrid water-splitting cycle using copper sulfate and mixed copper oxides

NASA Technical Reports Server (NTRS)

Schreiber, J. D.; Remick, R. J.; Foh, S. E.; Mazumder, M. M.

1980-01-01

The Institute of Gas Technology has derived and developed a hybrid thermochemical water-splitting cycle based on mixed copper oxides and copper sulfate. Similar to other metal oxide-metal sulfate cycles that use a metal oxide to 'concentrate' electrolytically produced sulfuric acid, this cycle offers the advantage of producing oxygen (to be vented) and sulfur dioxide (to be recycled) in separate steps, thereby eliminating the need of another step to separate these gases. The conceptual process flow-sheet efficiency of the cycle promises to exceed 50%. It has been completely demonstrated in the laboratory with recycled materials. Research in the electrochemical oxidation of sulfur dioxide to produce sulfuric acid and hydrogen performed at IGT indicates that the cell performance goals of 200 mA/sq cm at 0.5 V will be attainable using relatively inexpensive electrode materials.

A demonstration of the antimicrobial effectiveness of various copper surfaces

PubMed Central

2013-01-01

Background Bacterial contamination on touch surfaces results in increased risk of infection. In the last few decades, work has been done on the antimicrobial properties of copper and its alloys against a range of micro-organisms threatening public health in food processing, healthcare and air conditioning applications; however, an optimum copper method of surface deposition and mass structure has not been identified. Results A proof-of-concept study of the disinfection effectiveness of three copper surfaces was performed. The surfaces were produced by the deposition of copper using three methods of thermal spray, namely, plasma spray, wire arc spray and cold spray The surfaces were then inoculated with meticillin-resistant Staphylococcus aureus (MRSA). After a two hour exposure to the surfaces, the surviving MRSA were assayed and the results compared. The differences in the copper depositions produced by the three thermal spray methods were examined in order to explain the mechanism that causes the observed differences in MRSA killing efficiencies. The cold spray deposition method was significantly more effective than the other methods. It was determined that work hardening caused by the high velocity particle impacts created by the cold spray technique results in a copper microstructure that enhances ionic diffusion, and copper ions are principally responsible for antimicrobial activity. Conclusions This test showed significant microbiologic differences between coatings produced by different spray techniques and demonstrates the importance of the copper application technique. The cold spray technique shows superior anti-microbial effectiveness caused by the high impact velocity imparted to the sprayed particles which results in high dislocation density and high ionic diffusivity. PMID:23537176

Copper-doped titanium dioxide nanoparticles as dual-functional labels for fabrication of electrochemical immunosensors.

PubMed

Zhang, Sen; Ma, Hongmin; Yan, Liangguo; Cao, Wei; Yan, Tao; Wei, Qin; Du, Bin

2014-09-15

Constructions of versatile electroactive labels are key issues in the development of electrochemical immunosensors. In this study, copper-doped titanium dioxide nanoparticle (Cu@TiO2) was synthesized and used as labels for fabrication of sandwich-type electrochemical immunosensors on glassy carbon electrode (GCE). Due to the presence of copper ions, Cu@TiO2 shows a strong response current when coupled to an electrode. The prepared nanocomposite also shows high electrocatalytic activity towards reduction of hydrogen peroxide (H2O2). The dual functionality of Cu@TiO2 enables the fabrication of immunosensor using different detection modes, that is, square wave voltammetry (SWV) or chronoamperometry (CA). While Cu@TiO2 was used as labels of secondary antibodies (Ab2), carboxyl functionalized graphene oxide (CFGO) was used as electrode materials to immobilize primary antibodies (Ab1). Using human immunoglobulin G (IgG) as a model analyte, the immunosensor shows high sensitivity, acceptable stability and good reproducibility for both detection modes. Under optimal conditions, a linear range from 0.1 pg/mL to 100 ng/mL with a detection limit of 0.052 pg/mL was obtained for SWV analysis. For CA analysis, a wider linear range from 0.01 pg/mL to 100 ng/mL and a lower detection limit of 0.0043 pg/mL were obtained. The proposed metal ion-based enzyme-free and noble metal-free immunosensor may have promising applications in clinical diagnoses and many other fields. Copyright © 2014 Elsevier B.V. All rights reserved.

CO2 Reduction Selective for C≥2 Products on Polycrystalline Copper with N-Substituted Pyridinium Additives.

PubMed

Han, Zhiji; Kortlever, Ruud; Chen, Hsiang-Yun; Peters, Jonas C; Agapie, Theodor

2017-08-23

Electrocatalytic CO 2 reduction to generate multicarbon products is of interest for applications in artificial photosynthetic schemes. This is a particularly attractive goal for CO 2 reduction by copper electrodes, where a broad range of hydrocarbon products can be generated but where selectivity for C-C coupled products relative to CH 4 and H 2 remains an impediment. Herein we report a simple yet highly selective catalytic system for CO 2 reduction to C ≥2 hydrocarbons on a polycrystalline Cu electrode in bicarbonate aqueous solution that uses N-substituted pyridinium additives. Selectivities of 70-80% for C 2 and C 3 products with a hydrocarbon ratio of C ≥2 /CH 4 significantly greater than 100 have been observed with several additives. 13 C-labeling studies verify CO 2 to be the sole carbon source in the C ≥2 hydrocarbons produced. Upon electroreduction, the N-substituted pyridinium additives lead to film deposition on the Cu electrode, identified in one case as the reductive coupling product of N -arylpyridinium. Product selectivity can also be tuned from C ≥2 species to H 2 (∼90%) while suppressing methane with certain N-heterocyclic additives.

Ultra-high aspect ratio copper nanowires as transparent conductive electrodes for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Zhu, Zhaozhao; Mankowski, Trent; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine A.; Mansuripur, Masud; Falco, Charles M.

2016-09-01

We report the synthesis of ultra-high aspect ratio copper nanowires (CuNW) and fabrication of CuNW-based transparent conductive electrodes (TCE) with high optical transmittance (>80%) and excellent sheet resistance (Rs <30 Ω/sq). These CuNW TCEs are subsequently hybridized with aluminum-doped zinc oxide (AZO) thin-film coatings, or platinum thin film coatings, or nickel thin-film coatings. Our hybrid transparent electrodes can replace indium tin oxide (ITO) films in dye-sensitized solar cells (DSSCs) as either anodes or cathodes. We highlight the challenges of integrating bare CuNWs into DSSCs, and demonstrate that hybridization renders the solar cell integrations feasible. The CuNW/AZO-based DSSCs have reasonably good open-circuit voltage (Voc = 720 mV) and short-circuit current-density (Jsc = 0.96 mA/cm2), which are comparable to what is obtained with an ITO-based DSSC fabricated with a similar process. Our CuNW-Ni based DSSCs exhibit a good open-circuit voltage (Voc = 782 mV) and a decent short-circuit current (Jsc = 3.96 mA/cm2), with roughly 1.5% optical-to-electrical conversion efficiency.

Investigation on Low Firing Copper for Front Electrode of Si-Based Solar Cell Applications.

PubMed

Chiang, Chen-Su; Wu, Yia-Ming; Lee, Wen-Hsi

2018-04-01

Solar cell is one of the most popular alternative energies. The aim of this study is to construct an ohmic contact between front electrode and Si-based solar cell by a Newly-invented low-cost paste and low temperature sintering process. The core-shell of CucoreAgshell powders were prepared for making high solid content paste, then screen printing the fine line on laser-opening H-pattern silicon substrate and applying firing process. Because the silver coverage is more than 95% and silver nanoparticles start to melt at 200 °C. The shell of nanoparticles of silver not only is used to prevent copper from oxidized, but also connected core Cu particles for enhancing the conductivity of CucoreAgshell. TEM, EDS, SEM were used to examine the microstructure of CucoreAgshell. Fourpoint probe and transmission line model were employed to analyze the sheet resistance and the specific contact resistance. The lowest specific contact resistivity is 0.005 Ωcm2, sheet resistance is 0.0138 Ω/ and the lowest resistivity of front electrode measured is 2.65 × 10-5 Ωcm when CucoreAgshell paste with 94 wt% solid content was fired at 550 °C.

Fabrication of flower-like micro/nano dual scale structured copper oxide surfaces: Optimization of self-cleaning properties via Taguchi design

NASA Astrophysics Data System (ADS)

Moosavi, Saeideh Sadat; Norouzbeigi, Reza; Velayi, Elmira

2017-11-01

In the present work, copper oxide superhydrophobic surface is fabricated on a copper foil via the chemical bath deposition (CBD) method. The effects of some influential factors such as initial concentrations of Cu (II) ions and the surface energy modifier, solution pH, reaction and modification steps time on the wettability property of copper oxide surface were evaluated using Taguchi L16 experimental design. Results showed that the initial concentration of Cu (II) has the most significant impact on the water contact angle and wettability characteristics. The XRD, SEM, AFM and FTIR analyses were used to characterize the copper oxide surfaces. The Water contact angle (WCA) and contact angle hysteresis (CAH) were also measured. The SEM results indicated the formation of a flower-like micro/nano dual-scale structure of copper oxide on the substrate. This structure composed of numerous nano-petals with a thickness of about 50 nm. As a result, a copper oxide hierarchical surface with WCA of 168.4°± 3.5° and CAH of 2.73° exhibited the best superhydrophobicity under proposed optimum condition. This result has been obtained just by 10 min hydrolysis reaction. Besides, this surface showed a good stability under acidic and saline conditions.

Pure and Oxidized Copper Materials as Potential Antimicrobial Surfaces for Spaceflight Activities

NASA Astrophysics Data System (ADS)

Hahn, C.; Hans, M.; Hein, C.; Mancinelli, R. L.; Mücklich, F.; Wirth, R.; Rettberg, P.; Hellweg, C. E.; Moeller, R.

2017-12-01

Microbial biofilms can lead to persistent infections and degrade a variety of materials, and they are notorious for their persistence and resistance to eradication. During long-duration space missions, microbial biofilms present a danger to crew health and spacecraft integrity. The use of antimicrobial surfaces provides an alternative strategy for inhibiting microbial growth and biofilm formation to conventional cleaning procedures and the use of disinfectants. Antimicrobial surfaces contain organic or inorganic compounds, such as antimicrobial peptides or copper and silver, that inhibit microbial growth. The efficacy of wetted oxidized copper layers and pure copper surfaces as antimicrobial agents was tested by applying cultures of Escherichia coli and Staphylococcus cohnii to these metallic surfaces. Stainless steel surfaces were used as non-inhibitory control surfaces. The production of reactive oxygen species and membrane damage increased rapidly within 1 h of exposure on pure copper surfaces, but the effect on cell survival was negligible even after 2 h of exposure. However, longer exposure times of up to 4 h led to a rapid decrease in cell survival, whereby the survival of cells was additionally dependent on the exposed cell density. Finally, the release of metal ions was determined to identify a possible correlation between copper ions in suspension and cell survival. These measurements indicated a steady increase of free copper ions, which were released indirectly by cells presumably through excreted complexing agents. These data indicate that the application of antimicrobial surfaces in spaceflight facilities could improve crew health and mitigate material damage caused by microbial contamination and biofilm formation. Furthermore, the results of this study indicate that cuprous oxide layers were superior to pure copper surfaces related to the antimicrobial effect and that cell density is a significant factor that influences the time dependence of antimicrobial activity.

Post-treatment of molasses wastewater by electrocoagulation and process optimization through response surface analysis.

PubMed

Tsioptsias, C; Petridis, D; Athanasakis, N; Lemonidis, I; Deligiannis, A; Samaras, P

2015-12-01

Molasses wastewater is a high strength effluent of food industry such as distilleries, sugar and yeast production plants etc. It is characterized by a dark brown color and exhibits a high content in substances of recalcitrant nature such as melanoidins. In this study, electrocoagulation (EC) was studied as a post treatment step for biologically treated molasses wastewater with high nitrogen content obtained from a baker's yeast industry. Iron and copper electrodes were used in various forms; the influence and interaction of current density, molasses wastewater dilution, and reaction time, on COD, color, ammonium and nitrate removal rates and operating cost were studied and optimized through Box Behnken's response surface analysis. Reaction time varied from 0.5 to 4 h, current density varied from 5 to 40 mA/cm(2) and dilution from 0 to 90% (v/v expressed as water concentration). pH, conductivity and temperature measurements were also carried out during each experiment. From preliminary experiments, it was concluded that the application of aeration and sample dilution, considerably influenced the kinetics of the process. The obtained results showed that COD removal varied between 10 and 54%, corresponding to an operation cost ranging from 0.2 to 33 euro/kg COD removed. Significant removal rates were obtained for nitrogen as nitrate and ammonium (i.e. 70% ammonium removal). A linear relation of COD and ammonium to the design parameters was observed, while operation cost and nitrate removal responded in a curvilinear function. A low ratio of electrode surface to treated volume was used, associated to a low investment cost; in addition, iron wastes could be utilized as low cost electrodes i.e. iron fillings from lathes, aiming to a low operation cost due to electrodes replacement. In general, electrocoagulation proved to be an effective and low cost process for biologically treated molasses-wastewater treatment for additional removal of COD and nitrogen content and color reduction. Treated effluent samples with good quality were produced by EC, with COD, NH4-N and NO3-N concentrations of 180, 52 and 2 mg/l respectively. Response surface analysis revealed that optimized conditions could be established under moderate molasses wastewater dilution, (e.g. 45%), at 3.5 h treatment time and 33 mA/cm(2) current density. Copyright © 2015 Elsevier Ltd. All rights reserved.

The effect of iron and copper impurities on the wettability of sphalerite (110) surface.

PubMed

Simpson, Darren J; Bredow, Thomas; Chandra, Anand P; Cavallaro, Giuseppe P; Gerson, Andrea R

2011-07-15

The effect of impurities in the zinc sulfide mineral sphalerite on surface wettability has been investigated theoretically to shed light on previously reported conflicting results on sphalerite flotation. The effect of iron and copper impurities on the sphalerite (110) surface energy and on the water adsorption energy was calculated with the semi-empirical method modified symmetrically orthogonalized intermediate neglect of differential overlap (MSINDO) using the cyclic cluster model. The effect of impurities or dopants on surface energies is small but significant. The surface energy increases with increasing surface iron concentration while the opposite effect is reported for increasing copper concentration. The effect on adsorption energies is much more pronounced with water clearly preferring to adsorb on an iron site followed by a zinc site, and copper site least favorable. The theoretical results indicate that a sphalerite (110) surface containing iron is more hydrophilic than the undoped zinc sulfide surface. In agreement with the literature, the surface containing copper (either naturally or by activation) is more hydrophobic than the undoped surface. Copyright © 2011 Wiley Periodicals, Inc.

Influence of electrochemical potential on the displacement of aqueous electrolyte from a copper surface by oil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kendig, M.W.; Fadner, T.A.

1985-02-01

The forces responsible for the meniscus formed during the dynamic displacement of a 0.1 M H/sub 3/BO/sub 3/ + 0.5 M NaClO/sub 4/ solution by oil from a copper surface depend on the electrochemical potential of the copper and on an active component in the oil. For a nonpolar mineral oil containing oleic acid, a negative potential applied to copper produces hydrophilic behavior of the copper surface in the aqueous phase. This result is attribute largely to electrochemical destabilization of metallic soaps and possibly to electroosmotic transport.

From Laboratory Research to a Clinical Trial

PubMed Central

Michels, Harold T.; Keevil, C. William; Salgado, Cassandra D.; Schmidt, Michael G.

2015-01-01

Objective: This is a translational science article that discusses copper alloys as antimicrobial environmental surfaces. Bacteria die when they come in contact with copper alloys in laboratory tests. Components made of copper alloys were also found to be efficacious in a clinical trial. Background: There are indications that bacteria found on frequently touched environmental surfaces play a role in infection transmission. Methods: In laboratory testing, copper alloy samples were inoculated with bacteria. In clinical trials, the amount of live bacteria on the surfaces of hospital components made of copper alloys, as well as those made from standard materials, was measured. Finally, infection rates were tracked in the hospital rooms with the copper components and compared to those found in the rooms containing the standard components. Results: Greater than a 99.9% reduction in live bacteria was realized in laboratory tests. In the clinical trials, an 83% reduction in bacteria was seen on the copper alloy components, when compared to the surfaces made from standard materials in the control rooms. Finally, the infection rates were found to be reduced by 58% in patient rooms with components made of copper, when compared to patients' rooms with components made of standard materials. Conclusions: Bacteria die on copper alloy surfaces in both the laboratory and the hospital rooms. Infection rates were lowered in those hospital rooms containing copper components. Thus, based on the presented information, the placement of copper alloy components, in the built environment, may have the potential to reduce not only hospital-acquired infections but also patient treatment costs. PMID:26163568

Quasi-ballistic Electronic Thermal Conduction in Metal Inverse Opals.

PubMed

Barako, Michael T; Sood, Aditya; Zhang, Chi; Wang, Junjie; Kodama, Takashi; Asheghi, Mehdi; Zheng, Xiaolin; Braun, Paul V; Goodson, Kenneth E

2016-04-13

Porous metals are used in interfacial transport applications that leverage the combination of electrical and/or thermal conductivity and the large available surface area. As nanomaterials push toward smaller pore sizes to increase the total surface area and reduce diffusion length scales, electron conduction within the metal scaffold becomes suppressed due to increased surface scattering. Here we observe the transition from diffusive to quasi-ballistic thermal conduction using metal inverse opals (IOs), which are metal films that contain a periodic arrangement of interconnected spherical pores. As the material dimensions are reduced from ∼230 nm to ∼23 nm, the thermal conductivity of copper IOs is reduced by more than 57% due to the increase in surface scattering. In contrast, nickel IOs exhibit diffusive-like conduction and have a constant thermal conductivity over this size regime. The quasi-ballistic nature of electron transport at these length scales is modeled considering the inverse opal geometry, surface scattering, and grain boundaries. Understanding the characteristics of electron conduction at the nanoscale is essential to minimizing the total resistance of porous metals for interfacial transport applications, such as the total electrical resistance of battery electrodes and the total thermal resistance of microscale heat exchangers.

Metallic copper as an antimicrobial surface.

PubMed

Grass, Gregor; Rensing, Christopher; Solioz, Marc

2011-03-01

Bacteria, yeasts, and viruses are rapidly killed on metallic copper surfaces, and the term "contact killing" has been coined for this process. While the phenomenon was already known in ancient times, it is currently receiving renewed attention. This is due to the potential use of copper as an antibacterial material in health care settings. Contact killing was observed to take place at a rate of at least 7 to 8 logs per hour, and no live microorganisms were generally recovered from copper surfaces after prolonged incubation. The antimicrobial activity of copper and copper alloys is now well established, and copper has recently been registered at the U.S. Environmental Protection Agency as the first solid antimicrobial material. In several clinical studies, copper has been evaluated for use on touch surfaces, such as door handles, bathroom fixtures, or bed rails, in attempts to curb nosocomial infections. In connection to these new applications of copper, it is important to understand the mechanism of contact killing since it may bear on central issues, such as the possibility of the emergence and spread of resistant organisms, cleaning procedures, and questions of material and object engineering. Recent work has shed light on mechanistic aspects of contact killing. These findings will be reviewed here and juxtaposed with the toxicity mechanisms of ionic copper. The merit of copper as a hygienic material in hospitals and related settings will also be discussed.

Apparatus for the electrolytic production of metals

DOEpatents

Sadoway, Donald R.

1993-01-01

Improved electrolytic cells for producing metals by the electrolytic reduction of a compound dissolved in a molten electrolyte are disclosed. In the improved cells, at least one electrode includes a protective layer comprising an oxide of the cell product metal formed upon an alloy of the cell product metal and a more noble metal. In the case of an aluminum reduction cell, the electrode can comprise an alloy of aluminum with copper, nickel, iron, or combinations thereof, upon which is formed an aluminum oxide protective layer.

Role of polymeric binders on mechanical behavior and cracking resistance of silicon composite electrodes during electrochemical cycling

NASA Astrophysics Data System (ADS)

Li, Dawei; Wang, Yikai; Hu, Jiazhi; Lu, Bo; Dang, Dingying; Zhang, Junqian; Cheng, Yang-Tse

2018-05-01

This work focuses on understanding the role of various binders, including sodium alginate (SA), Nafion, and polyvinylidene fluoride (PVDF), on the mechanical behavior and cracking resistance of silicon composite electrodes during electrochemical cycling. In situ curvature measurement of bilayer electrodes, consisting of a silicon-binder-carbon black composite layer on a copper foil, is used to determine the effects of binders on bending deformation, elastic modulus, and stress on the composite electrodes. It is found that the lithiation induced curvature and the modulus of the silicon/SA electrodes are larger than those of electrodes with Nafion and PVDF as binders. Although the modulus of Nafion is smaller than that of PVDF, the curvature and the modulus of silicon/Nafion composite are larger than those of silicon/PVDF electrodes. The moduli of all three composites decrease not only during lithiation but also during delithiation. Based on the measured stress and scanning electron microscopy observations of cracking in the composite electrodes, we conclude that the stress required to crack the composite electrodes with SA and Nafion binders is considerably higher than that of the silicon/PVDF electrode during electrochemical cycling. Thus, the cracking resistance of silicon/SA and silicon/Nafion composite electrodes is higher than that of silicon/PVDF electrodes.

Enhanced gain and output power of a sealed-off rf-excited CO2 waveguide laser with gold-plated electrodes

NASA Astrophysics Data System (ADS)

Heeman-Ilieva, M. B.; Udalov, Yu. B.; Hoen, K.; Witteman, W. J.

1994-02-01

The small-signal gain and the laser output power have been measured in a cw sealed-off rf-excited CO2 waveguide laser for two different electrode materials, gold-plated copper and aluminum, at several excitation frequencies, gas pressures and mixture compositions. In the case of the gold-plated electrodes an enhancement of the gain up to a factor of 2 and the output power up to a factor of 1.4 with time at a frequency of 190 MHz and 60 Torr of 1:1:5+5% (CO2:N2:He+Xe) mixture is observed. This is believed to be the result of the gold catalytic activities which are favored by increased electrode temperatures and helium rich gas compositions.

A strategy to improve the energy conversion efficiency and stability of quantum dot-sensitized solar cells using manganese-doped cadmium sulfide quantum dots.

PubMed

Gopi, Chandu V V M; Venkata-Haritha, M; Kim, Soo-Kyoung; Kim, Hee-Je

2015-01-14

This article describes the effect of manganese (Mn) doping in CdS to improve the photovoltaic performance of quantum dot sensitized solar cells (QDSSCs). The performances of the QDSSCs are examined in detail using a polysulfide electrolyte with a copper sulfide (CuS) counter electrode. Under the illumination of one sun (AM 1.5 G, 100 mW cm(-2)), 10 molar% Mn-doped CdS QDSSCs exhibit a power conversion efficiency (η) of 2.85%, which is higher than the value of 2.11% obtained with bare CdS. The improved photovoltaic performance is due to the impurities from Mn(2+) doping of CdS, which have an impact on the structure of the host material and decrease the surface roughness. The surface roughness and morphology of Mn-doped CdS nanoparticles can be characterised from atomic force microscopy images. Furthermore, the cell device based on the Mn-CdS electrode shows superior stability in the sulfide/polysulfide electrolyte in a working state for over 10 h, resulting in a highly reproducible performance, which is a serious challenge for the Mn-doped solar cell. Our finding provides an effective method for the fabrication of Mn-doped CdS QDs, which can pave the way to further improve the efficiency of future QDSSCs.

Materials science and integration bases for fabrication of (BaxSr1-x)TiO3 thin film capacitors with layered Cu-based electrodes

NASA Astrophysics Data System (ADS)

Fan, W.; Kabius, B.; Hiller, J. M.; Saha, S.; Carlisle, J. A.; Auciello, O.; Chang, R. P. H.; Ramesh, R.

2003-11-01

The synthesis and fundamental material properties of layered TiAl/Cu/Ta electrodes were investigated to achieve the integration of Cu electrodes with high-dielectric constant (κ) oxide thin films for application to the fabrication of high-frequency devices. The Ta layer is an excellent diffusion barrier to inhibit deleterious Cu diffusion into the Si substrate, while the TiAl layer provides an excellent barrier against oxygen diffusion into the Cu layer to inhibit Cu oxidation during the growth of the high-κ layer in an oxygen atmosphere. Polycrystalline (BaxSr1-x)TiO3 (BST) thin films were grown on the Cu-based bottom electrode by rf magnetron sputtering at temperatures in the range 400-600 °C in oxygen, to investigate the performance of BST/Cu-based capacitors. Characterization of the Cu-based layered structure using surface analytical methods showed that two amorphous oxide layers were formed on both sides of the TiAl barrier, such that the oxide layer on the free surface of the TiAl layer correlates with TiAlOx, while the oxide layer at the TiAl/Cu interface is an Al2O3-rich layer. This double amorphous barrier layer structure effectively prevents oxygen penetration towards the underlying Cu and Ta layers. The TiAlOx interfacial layer, which has a relatively low dielectric constant compared with BST, reduced the total capacitance of the BST thin film capacitors. In addition, the layered electrode-oxide interface roughening observed during the growth of BST films at high temperature, due to copper grain growth, resulted in large dielectric loss on the fabricated BST capacitors. These problems were solved by growing the BST layer at 450 °C followed by a rapid thermal annealing at 700 °C. This process significantly reduced the thickness of the TiAlOx layer and interface roughness resulting in BST capacitors exhibiting properties suitable for the fabrication of high-performance high-frequency devices. In summary, relatively high dielectric constant (280), low dielectric loss (0.007), and low leakage current (<2×10-8 A/cm2 at 100 kV/cm) were achieved for BST thin film capacitors with Cu-based electrodes.

The Chemistry of Ultra-Radiopure Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miley, Harry S.; Aalseth, Craig E.; Day, Anthony R.

Ultra-pure materials are needed for the construction of the next generation of ultra-low level radiation detectors. These detectors are used for environmental research as well as rare nuclear decay experiments, e.g. probing the effective mass and character of the neutrino. Unfortunately, radioactive isotopes are found in most construction materials, either primordial isotopes, activation/spallation products from cosmic-ray exposure, or surface deposition of dust or radon progeny. Copper is an ideal candidate material for these applications. High-purity copper is commercially available and, when even greater radiopurity is needed, additional electrochemical purification can be combined with the final construction step, resulting in “electroformed”more » copper of extreme purity. Copper also offers desirable thermal, mechanical, and electrical properties. To bridge the gap between commercially-available high purity copper and the most stringent requirements of next-generation low-background experiments, a method of additional chemical purification is being developed based on well-known copper electrochemistry. This method is complemented with the co-development of surface cleaning techniques and more sensitive assay for both surface and bulk contamination. Developments in the electroplating of copper, surface cleaning, assay of U and Th in the bulk copper, and residual surface contamination will be discussed relative to goals of less than 1 microBq/kg Th.« less

Surface-rain interactions: differences in copper runoff for copper sheet of different inclination, orientation, and atmospheric exposure conditions.

PubMed

Hedberg, Yolanda S; Goidanich, Sara; Herting, Gunilla; Wallinder, Inger Odnevall

2015-01-01

Predictions of the diffuse dispersion of metals from outdoor constructions such as roofs and facades are necessary for environmental risk assessment and management. An existing predictive model has been compared with measured data of copper runoff from copper sheets exposed at four different inclinations facing four orientations at two different urban sites (Stockholm, Sweden, and Milan, Italy) during a 4-year period. Its applicability has also been investigated for copper sheet exposed at two marine sites(Cadiz, Spain, for 5 years, and Brest, France, for 9 years). Generally the model can be used for all given conditions. However, vertical surfaces should be considered as surfaces inclined 60-80 due to wind driven effects. The most important parameters that influence copper runoff, and not already included in the model, are the wind and rain characteristics that influence the actual rainfall volume impinging the surface of interest.

Role of alloying elements in adhesive transfer and friction of copper-base alloys

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1978-01-01

Sliding friction experiments were conducted in a vacuum with binary-copper alloy riders sliding against a conventional bearing-steel surface with normal residual oxides present. The binary alloys contained 1 atomic percent of various alloying elements. Auger spectroscopy analysis was used to monitor the adhesive transfer of the copper alloys to the bearing-steel surface. A relation was found to exist between adhesive transfer and the reaction potential and free energy of formation of the alloying element in the copper. The more chemically active the element and the more stable its oxide, the greater was the adhesive transfer and wear of the copper alloy. Transfer occurred in all the alloys except copper-gold after relatively few (25) passes across the steel surface.

Copper Tolerance and Biosorption of Saccharomyces cerevisiae during Alcoholic Fermentation

PubMed Central

Liu, Ling-ling; Jia, Bo; Zhao, Fang; Huang, Wei-dong; Zhan, Ji-cheng

2015-01-01

At high levels, copper in grape mash can inhibit yeast activity and cause stuck fermentations. Wine yeast has limited tolerance of copper and can reduce copper levels in wine during fermentation. This study aimed to understand copper tolerance of wine yeast and establish the mechanism by which yeast decreases copper in the must during fermentation. Three strains of Saccharomyces cerevisiae (lab selected strain BH8 and industrial strains AWRI R2 and Freddo) and a simple model fermentation system containing 0 to 1.50 mM Cu2+ were used. ICP-AES determined Cu ion concentration in the must decreasing differently by strains and initial copper levels during fermentation. Fermentation performance was heavily inhibited under copper stress, paralleled a decrease in viable cell numbers. Strain BH8 showed higher copper-tolerance than strain AWRI R2 and higher adsorption than Freddo. Yeast cell surface depression and intracellular structure deformation after copper treatment were observed by scanning electron microscopy and transmission electron microscopy; electronic differential system detected higher surface Cu and no intracellular Cu on 1.50 mM copper treated yeast cells. It is most probably that surface adsorption dominated the biosorption process of Cu2+ for strain BH8, with saturation being accomplished in 24 h. This study demonstrated that Saccharomyces cerevisiae strain BH8 has good tolerance and adsorption of Cu, and reduces Cu2+ concentrations during fermentation in simple model system mainly through surface adsorption. The results indicate that the strain selected from China’s stress-tolerant wine grape is copper tolerant and can reduce copper in must when fermenting in a copper rich simple model system, and provided information for studies on mechanisms of heavy metal stress. PMID:26030864

In vitro release of cupric ion from intrauterine devices: influence of frame, shape, copper surface area and indomethacin.

PubMed

Zhang, Shuangshuang; Li, Ying; Yu, Panpan; Chen, Tong; Zhou, Weisai; Zhang, Wenli; Liu, Jianping

2015-02-01

The release of cupric ion from copper intrauterine device (Cu-IUD) in human uterus is essential for contraception. However, excessive cupric ion will cause cytotoxic effect. In this paper, we investigated the influence of device characteristics (frame, copper surface area, shape, copper type and indomethacin) on copper release for the efficacy and adverse effects vary with IUD types which may correlate to their different release behaviors. Nine types of Cu-IUDs were selected and incubated in simulated uterine fluid. They were paired for comparison based on the device properties and the release of cupric ion was determined by flame atomic absorption spectrometer for about 160 days. The result showed that there was a burst release during the first month and the release rate tends to slow down and become steady afterwards. In addition, the copper release was mainly influenced by frame, indomethacin and copper type (copper wire and copper sleeve) while the shape variation had little effect on copper release throughout the experiment. Moreover, the influence of copper surface area was only noticeable during the first month. These findings were seldom reported before and may provide some useful information for the design of Cu-IUDs.

Investigation of an Electrochemical Method for Separation of Copper, Indium, and Gallium from Pretreated CIGS Solar Cell Waste Materials

PubMed Central

Gustafsson, Anna M. K.; Björefors, Fredrik; Steenari, Britt-Marie

2015-01-01

Recycling of the semiconductor material copper indium gallium diselenide (CIGS) is important to ensure a future supply of indium and gallium, which are relatively rare and therefore expensive elements. As a continuation of our previous work, where we recycled high purity selenium from CIGS waste materials, we now show that copper and indium can be recycled by electrodeposition from hydrochloric acid solutions of dissolved selenium-depleted material. Suitable potentials for the reduction of copper and indium were determined to be −0.5 V and −0.9 V (versus the Ag/AgCl reference electrode), respectively, using cyclic voltammetry. Electrodeposition of first copper and then indium from a solution containing the dissolved residue from the selenium separation and ammonium chloride in 1 M HCl gave a copper yield of 100.1 ± 0.5% and an indium yield of 98.1 ± 2.5%. The separated copper and indium fractions contained no significant contamination of the other elements. Gallium remained in solution together with a small amount of indium after the separation of copper and indium and has to be recovered by an alternative method since electrowinning from the chloride-rich acid solution was not effective. PMID:26347901

Impact of pH, dissolved inorganic carbon, and polyphosphates for the initial stages of water corrosion of copper surfaces investigated by AFM and NEXAFS

EPA Science Inventory

Nanoscale studies at the early stages of the exposure of copper surfaces after systematic treatments in synthesized water solutions can provide useful information about corrosion processes. The corrosion and passivation of copper surfaces as influenced by pH, dissolved inorganic ...

Fabrication of long-term stable superoleophobic surface based on copper oxide/cobalt oxide with micro-nanoscale hierarchical roughness

NASA Astrophysics Data System (ADS)

Barthwal, Sumit; Lim, Si-Hyung

2015-02-01

We have demonstrated a simple and cost-effective technique for the large-area fabrication of a superoleophobic surface using copper as a substrate. The whole process included three simple steps: First, the copper substrate was oxidized under hot alkaline conditions to fabricate flower-like copper oxide microspheres by heating at a particular temperature for an interval of time. Second, the copper-oxide-covered copper substrate was further heated in a solution of cobalt nitrate and ammonium nitrate in the presence of an ammonia solution to fabricate cobalt oxide nanostructures. We applied this second step to increase the surface roughness because it is an important criterion for improved superoleophobicity. Finally, to reduce the surface energy of the fabricated structures, the surfaces were chemically modified with perfluorooctyltrichlorosilane. Contact-angle measurements indicate that the micro-nano binary (MNB) hierarchical structures fabricated on the copper substrate became super-repellent toward a broad range of liquids with surface tension in the range of 21.5-72 mN/m. In an attempt to significantly improve the superoleophobic property of the surface, we also examined and compared the role of nanostructures in MNB hierarchical structures with only micro-fabricated surfaces. The fabricated MNB hierarchical structures also displays thermal stability and excellent long-term stability after exposure in air for more than 9 months. Our method might provide a general route toward the preparation of novel hierarchical films on metal substrates for various industrial applications.

Surface EMG electrodes do not accurately record from lumbar multifidus muscles.

PubMed

Stokes, Ian A F; Henry, Sharon M; Single, Richard M

2003-01-01

This study investigated whether electromyographic signals recorded from the skin surface overlying the multifidus muscles could be used to quantify their activity. Comparison of electromyography signals recorded from electrodes on the back surface and from wire electrodes within four different slips of multifidus muscles of three human subjects performing isometric tasks that loaded the trunk from three different directions. It has been suggested that suitably placed surface electrodes can be used to record activity in the deep multifidus muscles. We tested whether there was a stronger correlation and more consistent regression relationship between signals from electrodes overlying multifidus and longissimus muscles respectively than between signals from within multifidus and from the skin surface electrodes over multifidus. The findings provided consistent evidence that the surface electrodes placed over multifidus muscles were more sensitive to the adjacent longissimus muscles than to the underlying multifidus muscles. The R(2) for surface versus intra-muscular comparisons was 0.64, while the average R(2) for surface-multifidus versus surface-longissimus comparisons was 0.80. Also, the magnitude of the regression coefficients was less variable between different tasks for the longissimus versus surface multifidus comparisons. Accurate measurement of multifidus muscle activity requires intra-muscular electrodes. Electromyography is the accepted technique to document the level of muscular activation, but its specificity to particular muscles depends on correct electrode placement. For multifidus, intra-muscular electrodes are required.

Long-duration high-efficiency operation of a continuously pulsed copper laser utilizing copper bromide as a lasant

NASA Technical Reports Server (NTRS)

Chen, C. J.; Bhanji, A. M.; Russell, G. R.

1978-01-01

A copper laser utilizing copper bromide as a lasant and neon as the buffer gas has been operated at an average laser power of between 16 and 19.5 W for a period of 68 h. Lasing was attained at a pulsing rate of 16.7 kHz in a quartz discharge tube 2.5-cm in diameter with an electrode separation of 200 cm. The laser energy/pulse and peak power/pulse corresponding to an average power of 19.5 W are 1.2 mJ and 30 kW, respectively. The ratio of laser power at 510.6 and 578.2 nm varied from 3.9 to 1.1 corresponding to a total average laser power of 4 and 18 W, respectively. The highest wall plug and capacitor efficiency measured during 68 h of operation were 0.7 and 1.1%, respectively.

Cost-Effective Fabrication of Wettability Gradient Copper Surface by Screen Printing and its Application to Condensation Heat Transfer

NASA Astrophysics Data System (ADS)

Leu, Tzong-Shyng; Huang, Hung-Ming; Huang, Ding-Jun

2016-06-01

In this paper, wettability gradient pattern is applied to condensation heat transfer on a copper tube surface. For this application, the vital issue is how to fabricate gradient patterns on a curve tube surface to accelerate the droplet collection efficiently. For this purpose, novel fabrication processes are developed to form wettability gradient patterns on a curve copper tube surface by using roller screen printing surface modification techniques. The roller screen printing surface modification techniques can easily realize wettability gradient surfaces with superhydrophobicity and superhydrophilicity on a copper tube surface. Experimental results show the droplet nucleation sites, movement and coalescence toward the collection areas can be effectively controlled which can assist in removing the condensation water from the surface. The effectiveness of droplet collection is appropriate for being applied to condensation heat transfer in the foreseeable future.

Copper Alloy For High-Temperature Uses

NASA Technical Reports Server (NTRS)

Dreshfield, Robert L.; Ellis, David L.; Michal, Gary

1994-01-01

Alloy of Cu/8Cr/4Nb (numbers indicate parts by atom percent) improved over older high-temperature copper-based alloys in that it offers enhanced high temperature strength, resistance to creep, and ductility while retaining most of thermal conductivity of pure copper; in addition, alloy does not become embrittled upon exposure to hydrogen at temperatures as high as 705 degrees C. Designed for use in presence of high heat fluxes and active cooling; for example, in heat exchangers in advanced aircraft and spacecraft engines, and other high-temperature applications in which there is need for such material. High conductivity and hardness of alloy exploited in welding electrodes and in high-voltage and high-current switches and other applications in which wear poses design problem.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beck, M. A., E-mail: mabeck2@wisc.edu; Isaacs, J. A.; Booth, D.

We describe the design and characterization of superconducting coplanar waveguide cavities tailored to facilitate strong coupling between superconducting quantum circuits and single trapped Rydberg atoms. For initial superconductor–atom experiments at 4.2 K, we show that resonator quality factors above 10{sup 4} can be readily achieved. Furthermore, we demonstrate that the incorporation of thick-film copper electrodes at a voltage antinode of the resonator provides a route to enhance the zero-point electric fields of the resonator in a trapping region that is 40 μm above the chip surface, thereby minimizing chip heating from scattered trap light. The combination of high resonator quality factor andmore » strong electric dipole coupling between the resonator and the atom should make it possible to achieve the strong coupling limit of cavity quantum electrodynamics with this system.« less

Structure and morphology of CdS thin films electrodeposited in fused salts

NASA Astrophysics Data System (ADS)

Markov, I.; Valova, E.; Ilieva, M.; Kristev, I.

1983-12-01

Thin films of CdS are catholically electrodeposited on copper and silver electrodes in solution of CdCl 2 and Na 2SO 3 in fused LiCl-KCl eutectic. The films consist only of the hexagonal wurtzite phase of CdS. The films grown on Cu substrates are polycrystalline without pronounced fibre texture. The films grown on Ag substrates show practically perfect (000-) texture exposing the Cd face at the film surface. Films deposited at high bath temperatures (450-500°C), low current densities (0.2-0.5 mA/cm 2) or doped with In during the growth are very smooth. From the morphological investigations it is concluded that the CdS films electrodeposited onto Ag substrates have well pronounced laminar structure.

Characterization of Copper Corrosion Products in Drinking Water by Combining Electrochemical and Surface Analyses

EPA Science Inventory

This study focuses on the application of electrochemical approaches to drinking water copper corrosion problems. Applying electrochemical approaches combined with copper solubility measurements, and solid surface analysis approaches were discussed. Tafel extrapolation and Electro...

Characterization of Copper Corrosion Products Formed in Drinking Water by Combining Electrochemical and Surface Analyses

EPA Science Inventory

This study focuses on the application of electrochemical approaches to drinking water copper corrosion problems. Applying electrochemical approaches combined with copper solubility measurements, and solid surface analysis approaches were discussed. Tafel extrapolation and Electro...

Electrode holder useful in a corrosion testing device

DOEpatents

Murphy, R.J. Jr.; Jamison, D.E.

1986-08-19

The present invention is directed to an apparatus and method for holding one or more test electrodes of precisely known exposed surface area. The present invention is particularly useful in a device for determining the corrosion properties of the materials from which the test electrodes have been formed. The present invention relates to a device and method for holding the described electrodes wherein the exposed surface area of the electrodes is only infinitesimally decreased. Further, in the present invention the exposed, electrically conductive surface area of the contact devices is small relative to the test electrode surface area. The holder of the present invention conveniently comprises a device for contacting and engaging each test electrode at two point contacts infinitesimally small in relation to the exposed surface area of the electrodes. 4 figs.

Electrode holder useful in a corrosion testing device

DOEpatents

Murphy, Jr., Robert J.; Jamison, Dale E.

1986-01-01

The present invention is directed to an apparatus and method for holding one or more test electrodes of precisely known exposed surface area. The present invention is particularly useful in a device for determining the corrosion properties of the materials from which the test electrodes have been formed. The present invention relates to a device and method for holding the described electrodes wherein the exposed surface area of the electrodes is only infinitesimally decreased. Further, in the present invention the exposed, electrically conductive surface area of the contact devices is small relative to the test electrode surface area. The holder of the present invention conveniently comprises a device for contacting and engaging each test electrode at two point contacts infinitesimally small in relation to the exposed surface area of the electrodes.

Methods of conditioning direct methanol fuel cells

DOEpatents

Rice, Cynthia; Ren, Xiaoming; Gottesfeld, Shimshon

2005-11-08

Methods for conditioning the membrane electrode assembly of a direct methanol fuel cell ("DMFC") are disclosed. In a first method, an electrical current of polarity opposite to that used in a functioning direct methanol fuel cell is passed through the anode surface of the membrane electrode assembly. In a second method, methanol is supplied to an anode surface of the membrane electrode assembly, allowed to cross over the polymer electrolyte membrane of the membrane electrode assembly to a cathode surface of the membrane electrode assembly, and an electrical current of polarity opposite to that in a functioning direct methanol fuel cell is drawn through the membrane electrode assembly, wherein methanol is oxidized at the cathode surface of the membrane electrode assembly while the catalyst on the anode surface is reduced. Surface oxides on the direct methanol fuel cell anode catalyst of the membrane electrode assembly are thereby reduced.

Role of copper oxides in contact killing of bacteria.

PubMed

Hans, Michael; Erbe, Andreas; Mathews, Salima; Chen, Ying; Solioz, Marc; Mücklich, Frank

2013-12-31

The potential of metallic copper as an intrinsically antibacterial material is gaining increasing attention in the face of growing antibiotics resistance of bacteria. However, the mechanism of the so-called "contact killing" of bacteria by copper surfaces is poorly understood and requires further investigation. In particular, the influences of bacteria-metal interaction, media composition, and copper surface chemistry on contact killing are not fully understood. In this study, copper oxide formation on copper during standard antimicrobial testing was measured in situ by spectroscopic ellipsometry. In parallel, contact killing under these conditions was assessed with bacteria in phosphate buffered saline (PBS) or Tris-Cl. For comparison, defined Cu2O and CuO layers were thermally generated and characterized by grazing incidence X-ray diffraction. The antibacterial properties of these copper oxides were tested under the conditions used above. Finally, copper ion release was recorded for both buffer systems by inductively coupled plasma atomic absorption spectroscopy, and exposed copper samples were analyzed for topographical surface alterations. It was found that there was a fairly even growth of CuO under wet plating conditions, reaching 4-10 nm in 300 min, but no measurable Cu2O was formed during this time. CuO was found to significantly inhibit contact killing, compared to pure copper. In contrast, thermally generated Cu2O was essentially as effective in contact killing as pure copper. Copper ion release from the different surfaces roughly correlated with their antibacterial efficacy and was highest for pure copper, followed by Cu2O and CuO. Tris-Cl induced a 10-50-fold faster copper ion release compared to PBS. Since the Cu2O that primarily forms on copper under ambient conditions is as active in contact killing as pure copper, antimicrobial objects will retain their antimicrobial properties even after oxide formation.

Understanding the antimicrobial activity behind thin- and thick-rolled copper plates.

PubMed

Yousuf, Basit; Ahire, Jayesh J; Dicks, Leon M T

2016-06-01

The aim of this study was to compare the antibacterial properties of the surfaces of copper plates that were rolled to a thickness of 25 and 100 μm. Differences in topology of 25- and 100-μm-thick copper plates were studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). Antibacterial activity of the copper surfaces was tested against strains of Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Listeria monocytogenes, Salmonella typhimurium, Streptococcus sp. BY1, Enterococcus sp. BY2, and Bacillus cereus BY3. Changes in viable cell numbers were determined by plating onto optimal growth media and staining with LIVE/DEAD BacLight™. Changes in metabolic activity were recorded by expression of the luciferase (lux) gene. Cell morphology was studied using SEM. Accumulation and diffusion of copper from cells were recorded using inductively coupled plasma mass spectroscopy (ICP-MS). Lipid and protein oxidation were recorded spectrophotometrically. Surfaces of 25-μm-thick copper plates were rough compared to that of 100-μm-thick copper plates. For most species, a five-log reduction in cell numbers, cell membrane instability, and a decline in metabolic activity were recorded after 15 min of exposure to 25-μm-thick copper plates. Copper accumulated in the cells, and lipids and proteins were oxidized. The rough surface of thinner copper plates (25 μm thick) released more copper and was more antimicrobial compared to thicker (100 μm) copper plates. Cell death was attributed to destabilization of the cell membrane, lipid peroxidation, and protein oxidation.

Cu mesh for flexible transparent conductive electrodes.

PubMed

Kim, Won-Kyung; Lee, Seunghun; Hee Lee, Duck; Hee Park, In; Seong Bae, Jong; Woo Lee, Tae; Kim, Ji-Young; Hun Park, Ji; Chan Cho, Yong; Ryong Cho, Chae; Jeong, Se-Young

2015-06-03

Copper electrodes with a micromesh/nanomesh structure were fabricated on a polyimide substrate using UV lithography and wet etching to produce flexible transparent conducting electrodes (TCEs). Well-defined mesh electrodes were realized through the use of high-quality Cu thin films. The films were fabricated using radio-frequency (RF) sputtering with a single-crystal Cu target--a simple but innovative approach that overcame the low oxidation resistance of ordinary Cu. Hybrid Cu mesh electrodes were fabricated by adding a capping layer of either ZnO or Al-doped ZnO. The sheet resistance and the transmittance of the electrode with an Al-doped ZnO capping layer were 6.197 ohm/sq and 90.657%, respectively, and the figure of merit was 60.502 × 10(-3)/ohm, which remained relatively unchanged after thermal annealing at 200 °C and 1,000 cycles of bending. This fabrication technique enables the mass production of large-area flexible TCEs, and the stability and high performance of Cu mesh hybrid electrodes in harsh environments suggests they have strong potential for application in smart displays and solar cells.

Electrochemical Studies of a Truncated Laccase Produced in Pichia pastoris

PubMed Central

Gelo-Pujic, Mirjana; Kim, Hyug-Han; Butlin, Nathan G.; Palmore, G. Tayhas R.

1999-01-01

The cDNA that encodes an isoform of laccase from Trametes versicolor (LCCI), as well as a truncated version (LCCIa), was subcloned and expressed by using the yeast Pichia pastoris as the heterologous host. The amino acid sequence of LCCIa is identical to that of LCCI except that the final 11 amino acids at the C terminus of LCCI are replaced with a single cysteine residue. This modification was introduced for the purpose of improving the kinetics of electron transfer between an electrode and the copper-containing active site of laccase. The two laccases (LCCI and LCCIa) are compared in terms of their relative activity with two substrates that have different redox potentials. Results from electrochemical studies on solutions containing LCCI and LCCIa indicate that the redox potential of the active site of LCCIa is shifted to more negative values (411 mV versus normal hydrogen electrode voltage) than that found in other fungal laccases. In addition, replacing the 11 codons at the C terminus of the laccase gene with a single cysteine codon (i.e., LCCI→LCCIa) influences the rate of heterogeneous electron transfer between an electrode and the copper-containing active site (khet for LCCIa = 1.3 × 10−4 cm s−1). These results demonstrate for the first time that the rate of electron transfer between an oxidoreductase and an electrode can be enhanced by changes to the primary structure of a protein via site-directed mutagenesis. PMID:10584012

Glassy carbon electrode modified with polyanilne/ethylenediamine for detection of copper ions

NASA Astrophysics Data System (ADS)

Patil, Harshada K.; Deshmukh, Megha A.; Bodkhe, Gajanan A.; Shirsat, Mahendra D.

2018-05-01

Increasing water pollution is having high concern, since it creates the threats to all leaving organisms of existence. Industrial sewages have not only polluted the main stream lines of water, also the ground level water is having serious contaminations. Heavy metal ions are the pollutants which are not degradable and can be accumulated on living things ultimately the excess accumulation results into the serious concerns. Therefore, it is necessary to develop the sensors which can detect the heavy metal ions up to its maximum contamination limits. Conducting polymers are the materials which possess large application spectra. This investigation reports the electrochemically synthesized polyaniline (PANI) for modification of glassy carbon electrode (GCE). Ethylenediamine (EDA) - chelating ligand used for the modification of polyaniline so as to inculcate the selectivity toward copper ions Cu (II). The electrochemical cyclic voltammetry (CV) was used for the study of redox characteristics of PANI and influence of EDA modification. The result of CV has shown the reduced oxidation and reduction peak currents after modification indicating the domination of EDA. GCE modified with PANI/EDA was then employed for the detection of divalent copper ions and have shown the affinity toward Cu ions. The detection limit achieved was equal to 10mg/lit.

Synthesis of polymer-stabilized monometallic Cu and bimetallic Cu/Ag nanoparticles and their surface-enhanced Raman scattering properties

NASA Astrophysics Data System (ADS)

Zhang, Danhui; Liu, Xiaoheng

2013-03-01

The present study demonstrates a facile process for the production of spherical-shaped Cu and Ag nanoparticles synthesized and stabilized by hydrazine and gelatin, respectively. Advantages of the synthetic method include its production of water dispersible copper and copper/silver nanoparticles at room temperature under no inert atmosphere. The resulting nanoparticles (copper or copper/silver) are investigated by X-ray diffraction (XRD), UV-vis spectroscopy, and transmission electron microscopy (TEM). The nanometallic dispersions were characterized by surface plasmon absorbance measuring at 420 and 572 nm for Ag and Cu nanoparticles, respectively. Transmission electron microscopy showed the formation of nanoparticles in the range of ˜10 nm (silver), and ˜30 nm (copper). The results also demonstrate that the reducing order of Cu2+/Ag+ is important for the formation of the bimetallic nanoparticles. The surface-enhanced Raman scattering effects of copper and copper/silver nanoparticles were also displayed. It was found that the enhancement ability of copper/silver nanoparticles was little higher than the copper nanoparticles.

Deposition of Antimicrobial Copper-Rich Coatings on Polymers by Atmospheric Pressure Jet Plasmas

PubMed Central

Kredl, Jana; Kolb, Juergen F.; Schnabel, Uta; Polak, Martin; Weltmann, Klaus-Dieter; Fricke, Katja

2016-01-01

Inanimate surfaces serve as a permanent reservoir for infectious microorganisms, which is a growing problem in areas in everyday life. Coating of surfaces with inorganic antimicrobials, such as copper, can contribute to reduce the adherence and growth of microorganisms. The use of a DC operated air plasma jet for the deposition of copper thin films on acrylonitrile butadiene styrene (ABS) substrates is reported. ABS is a widespread material used in consumer applications, including hospitals. The influence of gas flow rate and input current on thin film characteristics and its bactericidal effect have been studied. Results from X-ray photoelectron spectroscopy (XPS) and atomic force microscopy confirmed the presence of thin copper layers on plasma-exposed ABS and the formation of copper particles with a size in the range from 20 to 100 nm, respectively. The bactericidal properties of the copper-coated surfaces were tested against Staphylococcus aureus. A reduction in growth by 93% compared with the attachment of bacteria on untreated samples was observed for coverage of the surface with 7 at. % copper. PMID:28773396

Organic light emitting diode with surface modification layer

DOEpatents

Basil, John D.; Bhandari, Abhinav; Buhay, Harry; Arbab, Mehran; Marietti, Gary J.

2017-09-12

An organic light emitting diode (10) includes a substrate (12) having a first surface (14) and a second surface (16), a first electrode (32), and a second electrode (38). An emissive layer (36) is located between the first electrode (32) and the second electrode (38). The organic light emitting diode (10) further includes a surface modification layer (18). The surface modification layer (18) includes a non-planar surface (30, 52).

Method For Plasma Source Ion Implantation And Deposition For Cylindrical Surfaces

DOEpatents

Fetherston, Robert P. , Shamim, Muhammad M. , Conrad, John R.

1997-12-02

Uniform ion implantation and deposition onto cylindrical surfaces is achieved by placing a cylindrical electrode in coaxial and conformal relation to the target surface. For implantation and deposition of an inner bore surface the electrode is placed inside the target. For implantation and deposition on an outer cylindrical surface the electrode is placed around the outside of the target. A plasma is generated between the electrode and the target cylindrical surface. Applying a pulse of high voltage to the target causes ions from the plasma to be driven onto the cylindrical target surface. The plasma contained in the space between the target and the electrode is uniform, resulting in a uniform implantation or deposition of the target surface. Since the plasma is largely contained in the space between the target and the electrode, contamination of the vacuum chamber enclosing the target and electrodes by inadvertent ion deposition is reduced. The coaxial alignment of the target and the electrode may be employed for the ion assisted deposition of sputtered metals onto the target, resulting in a uniform coating of the cylindrical target surface by the sputtered material. The independently generated and contained plasmas associated with each cylindrical target/electrode pair allows for effective batch processing of multiple cylindrical targets within a single vacuum chamber, resulting in both uniform implantation or deposition, and reduced contamination of one target by adjacent target/electrode pairs.

Thermal and Surface Evaluation on The Process of Forming a Cu2O/CuO Semiconductor Photocatalyst on a Thin Copper Plate

NASA Astrophysics Data System (ADS)

Zainul, R.; Oktavia, B.; Dewata, I.; Efendi, J.

2018-04-01

This research aims to investigate the process of forming a multi-scale copper oxide semiconductor (CuO/Cu2O) through a process of calcining a copper plate. The changes that occur during the formation of the oxide are thermally and surface evaluated. Evaluation using Differential Thermal Analysis (DTA) obtained by surface change of copper plate happened at temperature 380°C. Calcination of oxide formation was carried out at temperature 380°C for 1 hour. Surface evaluation process by using Scanning Electron Microscope (SEM) surface and cross-section, to determine diffusion of oxide formation on copper plate. The material composition is monitored by XRF and XRD to explain the process of structural and physical changes of the copper oxide plate formed during the heating process. The thickness of Cu plates used is 200-250 μm. SEM analysis results, the oxygen atom interruption region is in the range of 20-30 μm, and diffuses deeper during thermal oxidation process. The maximum diffusion depth of oxygen atoms reaches 129 μm.

Tungsten-yttria carbide coating for conveying copper

DOEpatents

Rothman, Albert J.

1993-01-01

A method is provided for providing a carbided-tungsten-yttria coating on the interior surface of a copper vapor laser. The surface serves as a wick for the condensation of liquid copper to return the condensate to the interior of the laser for revolatilization.

Laser cladding of stainless steel with a copper-silver alloy to generate surfaces of high antimicrobial activity

NASA Astrophysics Data System (ADS)

Hans, Michael; Támara, Juan Carlos; Mathews, Salima; Bax, Benjamin; Hegetschweiler, Andreas; Kautenburger, Ralf; Solioz, Marc; Mücklich, Frank

2014-11-01

Copper and silver are used as antimicrobial agents in the healthcare sector in an effort to curb infections caused by bacteria resistant to multiple antibiotics. While the bactericidal potential of copper and silver alone are well documented, not much is known about the antimicrobial properties of copper-silver alloys. This study focuses on the antibacterial activity and material aspects of a copper-silver model alloy with 10 wt% Ag. The alloy was generated as a coating with controlled intermixing of copper and silver on stainless steel by a laser cladding process. The microstructure of the clad was found to be two-phased and in thermal equilibrium with minor Cu2O inclusions. Ion release and killing of Escherichia coli under wet conditions were assessed with the alloy, pure silver, pure copper and stainless steel. It was found that the copper-silver alloy, compared to the pure elements, exhibited enhanced killing of E. coli, which correlated with an up to 28-fold increased release of copper ions. The results show that laser cladding with copper and silver allows the generation of surfaces with enhanced antimicrobial properties. The process is particularly attractive since it can be applied to existing surfaces.

Self-assembled three-dimensional and compressible interdigitated thin-film supercapacitors and batteries

PubMed Central

Nyström, Gustav; Marais, Andrew; Karabulut, Erdem; Wågberg, Lars; Cui, Yi; Hamedi, Mahiar M.

2015-01-01

Traditional thin-film energy-storage devices consist of stacked layers of active films on two-dimensional substrates and do not exploit the third dimension. Fully three-dimensional thin-film devices would allow energy storage in bulk materials with arbitrary form factors and with mechanical properties unique to bulk materials such as compressibility. Here we show three-dimensional energy-storage devices based on layer-by-layer self-assembly of interdigitated thin films on the surface of an open-cell aerogel substrate. We demonstrate a reversibly compressible three-dimensional supercapacitor with carbon nanotube electrodes and a three-dimensional hybrid battery with a copper hexacyanoferrate ion intercalating cathode and a carbon nanotube anode. The three-dimensional supercapacitor shows stable operation over 400 cycles with a capacitance of 25 F g−1 and is fully functional even at compressions up to 75%. Our results demonstrate that layer-by-layer self-assembly inside aerogels is a rapid, precise and scalable route for building high-surface-area 3D thin-film devices. PMID:26021485

A versatile chemical conversion synthesis of Cu2S nanotubes and the photovoltaic activities for dye-sensitized solar cell

PubMed Central

2014-01-01

A versatile, low-temperature, and low-cost chemical conversion synthesis has been developed to prepare copper sulfide (Cu2S) nanotubes. The successful chemical conversion from ZnS nanotubes to Cu2S ones profits by the large difference in solubility between ZnS and Cu2S. The morphology, structure, and composition of the yielded products have been examined by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements. We have further successfully employed the obtained Cu2S nanotubes as counter electrodes in dye-sensitized solar cells. The light-to-electricity conversion results show that the Cu2S nanostructures exhibit high photovoltaic conversion efficiency due to the increased surface area and the good electrocatalytical activity of Cu2S. The present chemical route provides a simple way to synthesize Cu2S nanotubes with a high surface area for nanodevice applications. PMID:25246878

Volume efficient sodium sulfur battery

DOEpatents

Mikkor, Mati

1980-01-01

In accordance with the teachings of this specification, a sodium sulfur battery is formed as follows. A plurality of box shaped sulfur electrodes are provided, the outer surfaces of which are defined by an electrolyte material. Each of the electrodes have length and width dimensions substantially greater than the thicknesses thereof as well as upwardly facing surface and a downwardly facing surface. An electrode structure is contained in each of the sulfur electrodes. A holding structure is provided for holding the plurality of sulfur electrodes in a stacked condition with the upwardly facing surface of one sulfur electrode in facing relationship to the downwardly facing surface of another sulfur electrode thereabove. A small thickness dimension separates each of the stacked electrodes thereby defining between each pair of sulfur electrodes a volume which receives the sodium reactant. A reservoir is provided for containing sodium. A manifold structure interconnects the volumes between the sulfur electrodes and the reservoir. A metering structure controls the flow of sodium between the reservoir and the manifold structure.

Low-cost electrodes for stable perovskite solar cells

NASA Astrophysics Data System (ADS)

Bastos, João P.; Manghooli, Sara; Jaysankar, Manoj; Tait, Jeffrey G.; Qiu, Weiming; Gehlhaar, Robert; De Volder, Michael; Uytterhoeven, Griet; Poortmans, Jef; Paetzold, Ulrich W.

2017-06-01

Cost-effective production of perovskite solar cells on an industrial scale requires the utilization of exclusively inexpensive materials. However, to date, highly efficient and stable perovskite solar cells rely on expensive gold electrodes since other metal electrodes are known to cause degradation of the devices. Finding a low-cost electrode that can replace gold and ensure both efficiency and long-term stability is essential for the success of the perovskite-based solar cell technology. In this work, we systematically compare three types of electrode materials: multi-walled carbon nanotubes (MWCNTs), alternative metals (silver, aluminum, and copper), and transparent oxides [indium tin oxide (ITO)] in terms of efficiency, stability, and cost. We show that multi-walled carbon nanotubes are the only electrode that is both more cost-effective and stable than gold. Devices with multi-walled carbon nanotube electrodes present remarkable shelf-life stability, with no decrease in the efficiency even after 180 h of storage in 77% relative humidity (RH). Furthermore, we demonstrate the potential of devices with multi-walled carbon nanotube electrodes to achieve high efficiencies. These developments are an important step forward to mass produce perovskite photovoltaics in a commercially viable way.

Superhydrophobic Copper Surfaces with Anticorrosion Properties Fabricated by Solventless CVD Methods.

PubMed

Vilaró, Ignasi; Yagüe, Jose L; Borrós, Salvador

2017-01-11

Due to continuous miniaturization and increasing number of electrical components in electronics, copper interconnections have become critical for the design of 3D integrated circuits. However, corrosion attack on the copper metal can affect the electronic performance of the material. Superhydrophobic coatings are a commonly used strategy to prevent this undesired effect. In this work, a solventless two-steps process was developed to fabricate superhydrophobic copper surfaces using chemical vapor deposition (CVD) methods. The superhydrophobic state was achieved through the design of a hierarchical structure, combining micro-/nanoscale domains. In the first step, O 2 - and Ar-plasma etchings were performed on the copper substrate to generate microroughness. Afterward, a conformal copolymer, 1H,1H,2H,2H-perfluorodecyl acrylate-ethylene glycol diacrylate [p(PFDA-co-EGDA)], was deposited on top of the metal via initiated CVD (iCVD) to lower the surface energy of the surface. The copolymer topography exhibited a very characteristic and unique nanoworm-like structure. The combination of the nanofeatures of the polymer with the microroughness of the copper led to achievement of the superhydrophobic state. AFM, SEM, and XPS were used to characterize the evolution in topography and chemical composition during the CVD processes. The modified copper showed water contact angles as high as 163° and hysteresis as low as 1°. The coating withstood exposure to aggressive media for extended periods of time. Tafel analysis was used to compare the corrosion rates between bare and modified copper. Results indicated that iCVD-coated copper corrodes 3 orders of magnitude slower than untreated copper. The surface modification process yielded repeatable and robust superhydrophobic coatings with remarkable anticorrosion properties.

CARBON NANOTUBE/COPPER COMPOSITE ELECTRODES FOR CAPILLARY ELECTROPHORESIS MICROCHIP DETECTION OF CARBOHYDRATES. (R830900)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

New insights on antimicrobial efficacy of copper surfaces in the healthcare environment: a systematic review.

PubMed

Chyderiotis, S; Legeay, C; Verjat-Trannoy, D; Le Gallou, F; Astagneau, P; Lepelletier, D

2018-03-29

Hospital-acquired infections (HAIs) are a major public health issue. The potential of antimicrobial copper surfaces in reducing HAIs' rates is of interest but remains unclear. We conducted a systematic review of studies assessing the activity of copper surfaces (colony-forming unit (CFU)/surface, both in vitro and in situ) as well as clinical studies. In vitro study protocols were analysed through a tailored checklist developed specifically for this review, in situ studies and non-randomized clinical studies were assessed using the ORION (Outbreak Reports and Intervention studies Of Nosocomial infection) checklist and randomized clinical studies using the CONSORT guidelines. The search was conducted using PubMed database with the keywords 'copper' and 'surfaces' and 'healthcare associated infections' or 'antimicrobial'. References from relevant articles, including reviews, were assessed and added when appropriate. Articles were added until 30 August 2016. Overall, 20 articles were selected for review including 10 in vitro, eight in situ and two clinical studies. Copper surfaces were found to have variable antimicrobial activity both in vitro and in situ, although the heterogeneity in the designs and the reporting of the results prevented conclusions from being drawn regarding their spectrum and activity/time compared to controls. Copper effect on HAIs incidence remains unclear because of the limited published data and the lack of robust designs. Most studies have potential conflicts of interest with copper industries. Copper surfaces have demonstrated an antimicrobial activity but the implications of this activity in healthcare settings are still unclear. No clear effect on healthcare associated infections has been demonstrated yet. Copyright © 2018 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

CO 2 Reduction Selective for C ≥2 Products on Polycrystalline Copper with N-Substituted Pyridinium Additives

DOE PAGES

Han, Zhiji; Kortlever, Ruud; Chen, Hsiang -Yun; ...

2017-07-21

Electrocatalytic CO 2 reduction to generate multicarbon products is of interest for applications in artificial photosynthetic schemes. This is a particularly attractive goal for CO 2 reduction by copper electrodes, where a broad range of hydrocarbon products can be generated but where selectivity for C–C coupled products relative to CH 4 and H 2 remains an impediment. Herein we report a simple yet highly selective catalytic system for CO 2 reduction to C ≥2 hydrocarbons on a polycrystalline Cu electrode in bicarbonate aqueous solution that uses N-substituted pyridinium additives. Selectivities of 70–80% for C 2 and C 3 products withmore » a hydrocarbon ratio of C ≥2/CH 4 significantly greater than 100 have been observed with several additives. 13C-labeling studies verify CO 2 to be the sole carbon source in the C ≥2 hydrocarbons produced. Upon electroreduction, the N-substituted pyridinium additives lead to film deposition on the Cu electrode, identified in one case as the reductive coupling product of N-arylpyridinium. As a result, product selectivity can also be tuned from C ≥2 species to H 2 (~90%) while suppressing methane with certain N-heterocyclic additives.« less

CO 2 Reduction Selective for C ≥2 Products on Polycrystalline Copper with N-Substituted Pyridinium Additives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Zhiji; Kortlever, Ruud; Chen, Hsiang -Yun

Electrocatalytic CO 2 reduction to generate multicarbon products is of interest for applications in artificial photosynthetic schemes. This is a particularly attractive goal for CO 2 reduction by copper electrodes, where a broad range of hydrocarbon products can be generated but where selectivity for C–C coupled products relative to CH 4 and H 2 remains an impediment. Herein we report a simple yet highly selective catalytic system for CO 2 reduction to C ≥2 hydrocarbons on a polycrystalline Cu electrode in bicarbonate aqueous solution that uses N-substituted pyridinium additives. Selectivities of 70–80% for C 2 and C 3 products withmore » a hydrocarbon ratio of C ≥2/CH 4 significantly greater than 100 have been observed with several additives. 13C-labeling studies verify CO 2 to be the sole carbon source in the C ≥2 hydrocarbons produced. Upon electroreduction, the N-substituted pyridinium additives lead to film deposition on the Cu electrode, identified in one case as the reductive coupling product of N-arylpyridinium. As a result, product selectivity can also be tuned from C ≥2 species to H 2 (~90%) while suppressing methane with certain N-heterocyclic additives.« less

Copper nanowire-graphene core-shell nanostructure for highly stable transparent conducting electrodes.

PubMed

Ahn, Yumi; Jeong, Youngjun; Lee, Donghwa; Lee, Youngu

2015-03-24

A copper nanowire-graphene (CuNW-G) core-shell nanostructure was successfully synthesized using a low-temperature plasma-enhanced chemical vapor deposition process at temperatures as low as 400 °C for the first time. The CuNW-G core-shell nanostructure was systematically characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman, and X-ray photoelectron spectroscopy measurements. A transparent conducting electrode (TCE) based on the CuNW-G core-shell nanostructure exhibited excellent optical and electrical properties compared to a conventional indium tin oxide TCE. Moreover, it showed remarkable thermal oxidation and chemical stability because of the tight encapsulation of the CuNW with gas-impermeable graphene shells. The potential suitability of CuNW-G TCE was demonstrated by fabricating bulk heterojunction polymer solar cells. We anticipate that the CuNW-G core-shell nanostructure can be used as an alternative to conventional TCE materials for emerging optoelectronic devices such as flexible solar cells, displays, and touch panels.

Water Purification Systems

NASA Technical Reports Server (NTRS)

1994-01-01

Clearwater Pool Technologies employs NASA-developed silver/copper ionization to purify turtle and dolphin tanks, cooling towers, spas, water recycling systems, etc. The pool purifier consists of a microcomputer to monitor water conditions, a pair of metallic electrodes, and a rheostat controller. Ions are generated by passing a low voltage current through the electrodes; the silver ions kill the bacteria, and the copper ions kill algae. This technology has found broad application because it offers an alternative to chemical disinfectants. It was originally developed to purify water on Apollo spacecraft. Caribbean Clear has been using NASA's silver ionization technology for water purification for more than a decade. Two new products incorporate advancements of the basic technology. One is the AquaKing, a system designed for areas with no source of acceptable drinking water. Another is the Caribbean Clear Controller, designed for commercial pool and water park applications where sanitizing is combined with feedback control of pH and an oxidizer, chlorine or bromine. The technology was originally developed to purify water on Apollo spacecraft.

Prototype of a scaled‐up microbial fuel cell for copper recovery

PubMed Central

Rodenas Motos, Pau; Molina, Gonzalo; Sleutels, Tom; Saakes, Michel; Buisman, Cees

2017-01-01

Abstract Background Bioelectrochemical systems (BESs) enable recovery of electrical energy through oxidation of a wide range of substrates at an anode and simultaneous recovery of metals at a cathode. Scale‐up of BESs from the laboratory to pilot scale is a challenging step in the development of the process, and there are only a few successful experiences to build on. This paper presents a prototype BES for the recovery of copper. Results The cell design presented here had removable electrodes, similar to those in electroplating baths. The anode and cathode in this design could be replaced independently. The prototype bioelectrochemical cell consisted of an 835 cm2 bioanode fed with acetate, and a 700 cm2 cathode fed with copper. A current density of 1.2 A/−2 was achieved with 48 mW m−2 of power production. The contribution of each component (anode, electrolytes, cathode and membrane) was evaluated through the analysis of the internal resistance distribution. This revealed that major losses occurred at the anode, and that the design with removable electrodes results in higher internal resistance compared with other systems. To further assess the practical applicability of BES for copper recovery, an economic evaluation was performed. Conclusion Analysis shows that the internal resistance of several lab‐scale BESs is already sufficiently low to make the system economic, while the internal resistance for scaled‐up systems still needs to be improved considerably to become economically applicable.© 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:29104342

Conductive polymer foam surface improves the performance of a capacitive EEG electrode.

PubMed

Baek, Hyun Jae; Lee, Hong Ji; Lim, Yong Gyu; Park, Kwang Suk

2012-12-01

In this paper, a new conductive polymer foam-surfaced electrode was proposed for use as a capacitive EEG electrode for nonintrusive EEG measurements in out-of-hospital environments. The current capacitive electrode has a rigid surface that produces an undefined contact area due to its stiffness, which renders it unable to conform to head curvature and locally isolates hairs between the electrode surface and scalp skin, making EEG measurement through hair difficult. In order to overcome this issue, a conductive polymer foam was applied to the capacitive electrode surface to provide a cushioning effect. This enabled EEG measurement through hair without any conductive contact with bare scalp skin. Experimental results showed that the new electrode provided lower electrode-skin impedance and higher voltage gains, signal-to-noise ratios, signal-to-error ratios, and correlation coefficients between EEGs measured by capacitive and conventional resistive methods compared to a conventional capacitive electrode. In addition, the new electrode could measure EEG signals, while the conventional capacitive electrode could not. We expect that the new electrode presented here can be easily installed in a hat or helmet to create a nonintrusive wearable EEG apparatus that does not make users look strange for real-world EEG applications.

The effects of printing orientation on the electrochemical behaviour of 3D printed acrylonitrile butadiene styrene (ABS)/carbon black electrodes.

PubMed

Bin Hamzah, Hairul Hisham; Keattch, Oliver; Covill, Derek; Patel, Bhavik Anil

2018-06-14

Additive manufacturing also known as 3D printing is being utilised in electrochemistry to reproducibly develop complex geometries with conductive properties. In this study, we explored if the electrochemical behavior of 3D printed acrylonitrile butadiene styrene (ABS)/carbon black electrodes was influenced by printing direction. The electrodes were printed in both horizontal and vertical directions. The horizsontal direction resulted in a smooth surface (HPSS electrode) and a comparatively rougher surface (HPRS electrode) surface. Electrodes were characterized using cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. For various redox couples, the vertical printed (VP) electrode showed enhanced current response when compared the two electrode surfaces generated by horizontal print direction. No differences in the capacitive response was observed, indicating that the conductive surface area of all types of electrodes were identical. The VP electrode had reduced charge transfer resistance and uncompensated solution resistance when compared to the HPSS and HPRS electrodes. Overall, electrodes printed in a vertical direction provide enhanced electrochemical performance and our study indicates that print orientation is a key factor that can be used to enhance sensor performance.

Influence of in-situ ion-beam sputter cleaning on the conditioning effect of vacuum gaps

NASA Astrophysics Data System (ADS)

Kobayashi, Shinichi; Kojima, Hiroyuki; Saito, Yoshio

1994-05-01

An ion beam sputtering technique was used to clean the electrode surfaces of vacuum gaps. Ions of the sputtering gas were irradiated by means of an ion gun in a vacuum chamber attached to a breakdown measurement chamber. By providing in situ ion-beam sputter cleaning, this system makes it possible to make measurements free from contamination due to exposure to the air. The sputtering gas was He or Ar, and the electrodes were made of oxygen-free copper (purity more than 99.96%). An impulse voltage with the wave form of 64/700 microsecond(s) was applied to the test gap, and the pressure in the breakdown measurement chamber at the beginning of breakdown tests was 1.3 X 10-8 Pa. These experiments showed that ion-beam sputter cleaning results in higher breakdown fields after a repetitive breakdown conditioning procedure, and that He is more effective in improving hold- off voltages after the conditioning (under the same ion current density, the breakdown field was 300 MV/m for He sputtering and 200 MV/m for Ar sputtering). The breakdown fields at the first voltage application after the sputtering cleaning, on the other hand, were not improved.

Continuous, highly flexible, and transparent graphene films by chemical vapor deposition for organic photovoltaics.

PubMed

Gomez De Arco, Lewis; Zhang, Yi; Schlenker, Cody W; Ryu, Koungmin; Thompson, Mark E; Zhou, Chongwu

2010-05-25

We report the implementation of continuous, highly flexible, and transparent graphene films obtained by chemical vapor deposition (CVD) as transparent conductive electrodes (TCE) in organic photovoltaic cells. Graphene films were synthesized by CVD, transferred to transparent substrates, and evaluated in organic solar cell heterojunctions (TCE/poly-3,4-ethylenedioxythiophene:poly styrenesulfonate (PEDOT:PSS)/copper phthalocyanine/fullerene/bathocuproine/aluminum). Key to our success is the continuous nature of the CVD graphene films, which led to minimal surface roughness ( approximately 0.9 nm) and offered sheet resistance down to 230 Omega/sq (at 72% transparency), much lower than stacked graphene flakes at similar transparency. In addition, solar cells with CVD graphene and indium tin oxide (ITO) electrodes were fabricated side-by-side on flexible polyethylene terephthalate (PET) substrates and were confirmed to offer comparable performance, with power conversion efficiencies (eta) of 1.18 and 1.27%, respectively. Furthermore, CVD graphene solar cells demonstrated outstanding capability to operate under bending conditions up to 138 degrees , whereas the ITO-based devices displayed cracks and irreversible failure under bending of 60 degrees . Our work indicates the great potential of CVD graphene films for flexible photovoltaic applications.

An investigation on the effect of deposition parameters on nanostructured electrode of lithium ion batteries and their performance

NASA Astrophysics Data System (ADS)

Dorri, Mehrdad; Zamani, Cyrus; Babaei, Alireza

2018-01-01

Nanostructured plate-like manganese cobalt oxide (MCO) was synthesized as the anode material for lithium-ion batteries. Under basic conditions and using a molar ratio of OH- /NO3-= 1.5, crystallite size of 14 nm was found for samples calcined at 350°C. The electrodes were fabricated by mixing MCO as the active material, Super P carbon as the conducting material and polyvinylidene fluoride (PVDF) as the binder in N-methyl-2-pyrrolidone (NMP) solvent. The slurry was coated onto a copper foil substrate. The aim of this investigation is the assessment of deposition parameters on different plausible defects (such as agglomeration/blisters, pinholes/divots, cracks and non-uniform coating) and also electrical behavior of the deposited layer. Because of high degree of agglomeration, mortar method was found to be ineffective while mixing using magnetic stirrer was proved to be more appropriate in terms of final rheology. The optimum value for the binder was found to be 2.73 wt% of the NMP solvent. Effective drying was achieved using hotplate followed by oven drying. SEM analysis revealed the disappearance of the surface cracks when samples are pressed after drying stage.

Ion manipulation device with electrical breakdown protection

DOEpatents

Chen, Tsung-Chi; Tang, Keqi; Ibrahim, Yehia M; Smith, Richard D; Anderson, Gordon A; Baker, Erin M

2014-12-02

An ion manipulation method and device is disclosed. The device includes a pair of substantially parallel surfaces. An array of inner electrodes is contained within, and extends substantially along the length of, each parallel surface. The device includes a first outer array of electrodes and a second outer array of electrodes. Each outer array of electrodes is positioned on either side of the inner electrodes, and is contained within and extends substantially along the length of each parallel surface. A DC voltage is applied to the first and second outer array of electrodes. A RF voltage, with a superimposed electric field, is applied to the inner electrodes by applying the DC voltages to each electrode. Ions either move between the parallel surfaces within an ion confinement area or along paths in the direction of the electric field, or can be trapped in the ion confinement area. The surfaces are housed in a chamber, and at least one electrically insulative shield is coupled to an inner surface of the chamber for increasing a mean-free-path between two adjacent electrodes in the chamber.

Spectroscopic and electrochemical behavior of the novel tetra-2-methyl-pyrazinoporphyrazines

NASA Astrophysics Data System (ADS)

Pişkin, Mehmet; Öztürk, Naciye; Durmuş, Mahmut

2017-12-01

This study presents the synthesis and characterization of novel metal-free (H2Pc) and metallo porphyrazines (magnesium(II) (MgPz), copper(II) (CuPz), iron(II) (FePz), manganese(II) (MnPz) and nickel(II) (NiPz)) substituted with four 2-methylpyrazine groups on the peripheral positions. The spectroscopic properties of newly synthesized porphyrazines were investigated. The electrochemical behaviors of these porphyrazines were also determined in DMSO solution by cyclic voltammetry (CV) and square wave voltammetry (SWV) methods on edge plane pyrolytic graphite electrode (EPPG) electrode.