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Sample records for graphite-polyurethane composite electrode

  1. Dielectric properties and electrical conductivity of flat micronic graphite/polyurethane composites

    NASA Astrophysics Data System (ADS)

    Plyushch, Artyom; Macutkevic, Jan; Kuzhir, Polina P.; Banys, Juras; Fierro, Vanessa; Celzard, Alain

    2016-03-01

    Results of broadband dielectric spectroscopy of flat micronic graphite (FMG)/polyurethane (PU) resin composites are presented in a wide temperature range (25-450 K). The electrical percolation threshold was found to lie between 1 and 2 vol. % of FMG. Above the percolation threshold, the composites demonstrated a huge hysteresis of properties on heating and cooling from room temperature up to 450 K, along with extremely high values of dielectric permittivity and electrical conductivity. Annealing proved to be a very simple but powerful tool for significantly improving the electrical properties of FMG-based composites. In order to explain this effect, the distributions of relaxation times were calculated by the complex impedance formalism. Below room temperature, both dielectric permittivity and electrical conductivity exhibited a very low temperature dependence, mainly caused by the different thermal properties of FMG and pure PU matrix.

  2. Electrode compositions

    DOEpatents

    Block, J.; Fan, X.

    1998-10-27

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

  3. Electrode compositions

    DOEpatents

    Block, Jacob; Fan, Xiyun

    1998-01-01

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

  4. Energy efficient graphite polyurethane electrically conductive coatings for thermally actuated smart materials

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, A.; Dervishi, E.; Berry, B.; Viswanathan, T.; Bourdo, S.; Kim, H.; Sproles, R.; Hudson, M. K.

    2007-02-01

    The concept of graphite-polyurethane coatings as efficient, electrical resistors is the focus of this paper. A 60-40 graphite-polyurethane mix (weight %) demonstrated an electrical resistivity of 40.71 Ω mm. The graphite-polyurethane mix was coated on electrically insulating Kapton tape, which was then wrapped on a nichrome wire (nominal dimensions: 100 mm length and 1.5 mm diameter). This three-phase assembly was heated by Joule heating of the graphite-polyurethane layer. Steady state temperatures as high as 180 °C were attained under free convection conditions, at a very low power requirement of about 2.5 W as opposed to about 18 W for uncoated wires. Interestingly, the effect on transients (heating and cooling times) was not as dramatic. Experiments were also performed under vacuum conditions, following which an analysis is offered regarding the different modes of heat transfer. These coatings can potentially be used as efficient resistors for highly conductive, moderately high temperature shape memory alloys (e.g. the copper-aluminium-nickel system) or electrically insulating shape memory polymers. Any other thermally activated shape memory alloy (e.g. the popular nickel-titanium system) may also use the coatings as resistors due to the potentially dramatic energy savings that may be realized without a dramatic adverse impact on the frequency response.

  5. Negative electrode composition

    DOEpatents

    Kaun, Thomas D.; Chilenskas, Albert A.

    1982-01-01

    A secondary electrochemical cell and a negative electrode composition for use therewith comprising a positive electrode containing an active material of a chalcogen or a transiton metal chalcogenide, a negative electrode containing a lithium-aluminum alloy and an amount of a ternary alloy sufficient to provide at least about 5 percent overcharge capacity relative to a negative electrode solely of the lithium-aluminum alloy, the ternary alloy comprising lithium, aluminum, and iron or cobalt, and an electrolyte containing lithium ions in contact with both of the positive and the negative electrodes. The ternary alloy is present in the electrode in the range of from about 5 percent to about 50 percent by weight of the electrode composition and may include lithium-aluminum-nickel alloy in combination with either the ternary iron or cobalt alloys. A plurality of series connected cells having overcharge capacity can be equalized on the discharge side without expensive electrical equipment.

  6. Uncharged positive electrode composition

    DOEpatents

    Kaun, Thomas D.; Vissers, Donald R.; Shimotake, Hiroshi

    1977-03-08

    An uncharged positive-electrode composition contains particulate lithium sulfide, another alkali metal or alkaline earth metal compound other than sulfide, e.g., lithium carbide, and a transition metal powder. The composition along with a binder, such as electrolytic salt or a thermosetting resin is applied onto an electrically conductive substrate to form a plaque. The plaque is assembled as a positive electrode within an electrochemical cell opposite to a negative electrode containing a material such as aluminum or silicon for alloying with lithium. During charging, lithium alloy is formed within the negative electrode and transition metal sulfide such as iron sulfide is produced within the positive electrode. Excess negative electrode capacity over that from the transition metal sulfide is provided due to the electrochemical reaction of the other than sulfide alkali metal or alkaline earth metal compound.

  7. Composite carbon foam electrode

    DOEpatents

    Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

    1997-05-06

    Carbon aerogels used as a binder for granulated materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

  8. Composite carbon foam electrode

    DOEpatents

    Mayer, Steven T.; Pekala, Richard W.; Kaschmitter, James L.

    1997-01-01

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivty and power to system energy.

  9. Composite Electrodes for Electrochemical Supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Jun; Yang, Quan Min; Zhitomirsky, Igor

    2010-03-01

    Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4-6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT) into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with total mass loading of 7-15 mg cm-2, showed a capacitive behavior in 0.5-M Na2SO4 solutions. The decrease in stirring time during precipitation of the nanofibers resulted in reduced agglomeration and higher specific capacitance (SC). The highest SC of 185 F g-1 was obtained at a scan rate of 2 mV s-1 for mass loading of 7 mg cm-2. The SC decreased with increasing scan rate and increasing electrode mass.

  10. Aluminum-carbon composite electrode

    DOEpatents

    Farahmandi, C. Joseph; Dispennette, John M.

    1998-07-07

    A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg.

  11. Aluminum-carbon composite electrode

    DOEpatents

    Farahmandi, C.J.; Dispennette, J.M.

    1998-07-07

    A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg. 3 figs.

  12. Lithium-aluminum-magnesium electrode composition

    DOEpatents

    Melendres, Carlos A.; Siegel, Stanley

    1978-01-01

    A negative electrode composition is presented for use in a secondary, high-temperature electrochemical cell. The cell also includes a molten salt electrolyte of alkali metal halides or alkaline earth metal halides and a positive electrode including a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent and a magnesium-aluminum alloy as a structural matrix. Various binary and ternary intermetallic phases of lithium, magnesium, and aluminum are formed but the electrode composition in both its charged and discharged state remains substantially free of the alpha lithium-aluminum phase and exhibits good structural integrity.

  13. Composite electrode for use in electrochemical cells

    DOEpatents

    Vanderborgh, N.E.; Huff, J.R.; Leddy, J.

    1987-10-16

    A porous composite electrode for use in electrochemical cells. The electrode has a first face and a second face defining a relatively thin section therebetween. The electrode is comprised of an ion conducting material, an electron conducting material, and an electrocatalyst. The volume concentration of the ion conducting material is greatest at the first face and is decreased across the section, while the volume concentration of the electron conducting material is greatest at the second face and decreases across the section of the electrode. Substantially all of the electrocatalyst is positioned within the electrode section in a relatively narrow zone where the rate of electron transport of the electrode is approximately equal to the rate of ion transport of the electrode. 4 figs., 1 tab.

  14. Composite electrode for use in electrochemical cells

    DOEpatents

    Vanderborgh, Nicholas E.; Huff, James R.; Leddy, Johna

    1989-01-01

    A porous composite electrode for use in electrochemical cells. The electrode has a first face and a second face defining a relatively thin section therebetween. The electrode is comprised of an ion conducting material, an electron conducting material, and an electrocatalyst. The volume concentration of the ion conducting material is greatest at the first face and is decreased across the section, while the volume concentration of the electron conducting material is greatest at the second face and decreases across the section of the electrode. Substantially all of the electrocatalyst is positioned within the electrode section in a relatively narrow zone where the rate of electron transport of the electrode is approximately equal to the rate of ion transport of the electrode.

  15. Composite electrode/electrolyte structure

    DOEpatents

    Visco, Steven J.; Jacobson, Craig P.; DeJonghe, Lutgard C.

    2004-01-27

    Provided is an electrode fabricated from highly electronically conductive materials such as metals, metal alloys, or electronically conductive ceramics. The electronic conductivity of the electrode substrate is maximized. Onto this electrode in the green state, a green ionic (e.g., electrolyte) film is deposited and the assembly is co-fired at a temperature suitable to fully densify the film while the substrate retains porosity. Subsequently, a catalytic material is added to the electrode structure by infiltration of a metal salt and subsequent low temperature firing. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in ionic (electrochemical) devices such as fuel cells and electrolytic gas separation systems.

  16. Composite substrate for bipolar electrodes

    DOEpatents

    Tekkanat, Bora; Bolstad, James J.

    1992-12-22

    Substrates for electrode systems, particularly those to be used for bipolar electrodes in zinc-bromine batteries, are disclosed. The substrates preferably include carbon-black as a conductive filler in a polymeric matrix, with reinforcing materials such as glass fibers. Warpage of the zinc-bromine electrodes which was experienced in the prior art and which was believed to be caused by physical expansion of the electrodes due to bromine absorption by the carbon-black, is substantially eliminated when new substrate fabrication techniques are employed. In the pesent invention, substrates are prepared using a lamination process known as glass mat reinforced thermoplastics technology or, in an alternate embodiment, the substrate is made using a slurry process.

  17. Composite substrate for bipolar electrodes

    DOEpatents

    Tekkanat, B.; Bolstad, J.J.

    1992-12-22

    Substrates for electrode systems, particularly those to be used for bipolar electrodes in zinc-bromine batteries, are disclosed. The substrates preferably include carbon-black as a conductive filler in a polymeric matrix, with reinforcing materials such as glass fibers. Warpage of the zinc-bromine electrodes which was experienced in the prior art and which was believed to be caused by physical expansion of the electrodes due to bromine absorption by the carbon-black, is substantially eliminated when new substrate fabrication techniques are employed. In the present invention, substrates are prepared using a lamination process known as glass mat reinforced thermoplastics technology or, in an alternate embodiment, the substrate is made using a slurry process. 4 figs.

  18. Lithium-aluminum-iron electrode composition

    DOEpatents

    Kaun, Thomas D.

    1979-01-01

    A negative electrode composition is presented for use in a secondary electrochemical cell. The cell also includes an electrolyte with lithium ions such as a molten salt of alkali metal halides or alkaline earth metal halides that can be used in high-temperature cells. The cell's positive electrode contains a a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent in an alloy of aluminum-iron. Various binary and ternary intermetallic phases of lithium, aluminum and iron are formed. The lithium within the intermetallic phase of Al.sub.5 Fe.sub.2 exhibits increased activity over that of lithium within a lithium-aluminum alloy to provide an increased cell potential of up to about 0.25 volt.

  19. Capacitor with a composite carbon foam electrode

    DOEpatents

    Mayer, Steven T.; Pekala, Richard W.; Kaschmitter, James L.

    1999-01-01

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid partides being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy.

  20. Capacitor with a composite carbon foam electrode

    DOEpatents

    Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

    1999-04-27

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  2. Inert electrode composition having agent for controlling oxide growth on electrode made therefrom

    DOEpatents

    Ray, Siba P.

    1986-01-01

    An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily. The electrode composition further includes a metal compound dopant which will aid in controlling the thickness of a protective oxide layer on at least the bottom portion of an electrode made therefrom during use.

  3. Inert electrode composition having agent for controlling oxide growth on electrode made therefrom

    DOEpatents

    Ray, S.P.

    1986-04-15

    An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily. The electrode composition further includes a metal compound dopant which will aid in controlling the thickness of a protective oxide layer on at least the bottom portion of an electrode made therefrom during use. 12 figs.

  4. Understanding the Effects of Electrode Formulation on the Mechanical Strength of Composite Electrodes for Flexible Batteries.

    PubMed

    Gaikwad, Abhinav M; Arias, Ana Claudia

    2017-02-22

    Flexible lithium-ion batteries are necessary for powering the next generation of wearable electronic devices. In most designs, the mechanical flexibility of the battery is improved by reducing the thickness of the active layers, which in turn reduces the areal capacity and energy density of the battery. The performance of a battery depends on the electrode composition, and in most flexible batteries, standard electrode formulation is used, which is not suitable for flexing. Even with considerable efforts made toward the development of flexible lithium-ion batteries, the formulation of the electrodes has received very little attention. In this study, we investigate the relation between the electrode formulation and the mechanical strength of the electrodes. Peel and drag tests are used to compare the adhesion and cohesion strength of the electrodes. The strength of an electrode is sensitive to the particle size and the choice of polymeric binder. By optimizing the electrode composition, we were able to fabricate a high areal capacity (∼2 mAh/cm(2)) flexible lithium-ion battery with conventional metal-based current collectors that shows superior electrochemical and mechanical performance in comparison to that of batteries with standard composition.

  5. Ionic Conduction in Lithium Ion Battery Composite Electrode Governs Cross-sectional Reaction Distribution

    NASA Astrophysics Data System (ADS)

    Orikasa, Yuki; Gogyo, Yuma; Yamashige, Hisao; Katayama, Misaki; Chen, Kezheng; Mori, Takuya; Yamamoto, Kentaro; Masese, Titus; Inada, Yasuhiro; Ohta, Toshiaki; Siroma, Zyun; Kato, Shiro; Kinoshita, Hajime; Arai, Hajime; Ogumi, Zempachi; Uchimoto, Yoshiharu

    2016-05-01

    Composite electrodes containing active materials, carbon and binder are widely used in lithium-ion batteries. Since the electrode reaction occurs preferentially in regions with lower resistance, reaction distribution can be happened within composite electrodes. We investigate the relationship between the reaction distribution with depth direction and electronic/ionic conductivity in composite electrodes with changing electrode porosities. Two dimensional X-ray absorption spectroscopy shows that the reaction distribution is happened in lower porosity electrodes. Our developed 6-probe method can measure electronic/ionic conductivity in composite electrodes. The ionic conductivity is decreased for lower porosity electrodes, which governs the reaction distribution of composite electrodes and their performances.

  6. Ionic Conduction in Lithium Ion Battery Composite Electrode Governs Cross-sectional Reaction Distribution

    PubMed Central

    Orikasa, Yuki; Gogyo, Yuma; Yamashige, Hisao; Katayama, Misaki; Chen, Kezheng; Mori, Takuya; Yamamoto, Kentaro; Masese, Titus; Inada, Yasuhiro; Ohta, Toshiaki; Siroma, Zyun; Kato, Shiro; Kinoshita, Hajime; Arai, Hajime; Ogumi, Zempachi; Uchimoto, Yoshiharu

    2016-01-01

    Composite electrodes containing active materials, carbon and binder are widely used in lithium-ion batteries. Since the electrode reaction occurs preferentially in regions with lower resistance, reaction distribution can be happened within composite electrodes. We investigate the relationship between the reaction distribution with depth direction and electronic/ionic conductivity in composite electrodes with changing electrode porosities. Two dimensional X-ray absorption spectroscopy shows that the reaction distribution is happened in lower porosity electrodes. Our developed 6-probe method can measure electronic/ionic conductivity in composite electrodes. The ionic conductivity is decreased for lower porosity electrodes, which governs the reaction distribution of composite electrodes and their performances. PMID:27193448

  7. Manganese oxide composite electrodes for lithium batteries

    DOEpatents

    Johnson, Christopher S.; Kang, Sun-Ho; Thackeray, Michael M.

    2009-12-22

    An activated electrode for a non-aqueous electrochemical cell is disclosed with a precursor thereof a lithium metal oxide with the formula xLi.sub.2MnO.sub.3.(1-x)LiMn.sub.2-yM.sub.yO.sub.4 for 0.5electrode and 0.ltoreq.y<1 in which the Li.sub.2MnO.sub.3 and LiMn.sub.2-yM.sub.yO.sub.4 components have layered and spinel-type structures, respectively, and in which M is one or more metal cations. The electrode is activated by removing lithia, or lithium and lithia, from the precursor. A cell and battery are also disclosed incorporating the disclosed positive electrode.

  8. Density impact on performance of composite Si/graphite electrodes

    SciTech Connect

    Dufek, Eric J.; Picker, Michael; Petkovic, Lucia M.

    2016-01-27

    The ability of alkali-substituted binders for composite Si and graphite negative electrodes to minimize capacity fade for lithium ion batteries is investigated. Polymer films and electrodes are described and characterized by FTIR following immersion in electrolyte (1:2 EC:DMC) for 24 h. FTIR analysis following electrode formation displayed similar alkali-ion dependent shifts in peak location suggesting that changes in the vibrational structure of the binder are maintained after electrode formation. The Si and graphite composite electrodes prepared using the alkali-substituted polyacrylates were also exposed to electrochemical cycling and it has been found that the performance of the Na-substituted binder is superior to a comparable density K-substituted system. However, in comparing performance across many different electrode densities attention needs to be placed on making comparisons at similar densities, as low density electrodes tend to exhibit lower capacity fade over cycling. This is highlighted by a 6% difference between a low density K-substituted electrode and a high density Na-substituted sample. As a result, this low variance between the two systems makes it difficult to quickly make a direct evaluation of binder performance unless electrode density is tightly controlled.

  9. Density impact on performance of composite Si/graphite electrodes

    DOE PAGES

    Dufek, Eric J.; Picker, Michael; Petkovic, Lucia M.

    2016-01-27

    The ability of alkali-substituted binders for composite Si and graphite negative electrodes to minimize capacity fade for lithium ion batteries is investigated. Polymer films and electrodes are described and characterized by FTIR following immersion in electrolyte (1:2 EC:DMC) for 24 h. FTIR analysis following electrode formation displayed similar alkali-ion dependent shifts in peak location suggesting that changes in the vibrational structure of the binder are maintained after electrode formation. The Si and graphite composite electrodes prepared using the alkali-substituted polyacrylates were also exposed to electrochemical cycling and it has been found that the performance of the Na-substituted binder is superiormore » to a comparable density K-substituted system. However, in comparing performance across many different electrode densities attention needs to be placed on making comparisons at similar densities, as low density electrodes tend to exhibit lower capacity fade over cycling. This is highlighted by a 6% difference between a low density K-substituted electrode and a high density Na-substituted sample. As a result, this low variance between the two systems makes it difficult to quickly make a direct evaluation of binder performance unless electrode density is tightly controlled.« less

  10. Manganese oxide composite electrodes for lithium batteries

    DOEpatents

    Thackeray, Michael M.; Johnson, Christopher S.; Li, Naichao

    2007-12-04

    An activated electrode for a non-aqueous electrochemical cell is disclosed with a precursor of a lithium metal oxide with the formula xLi.sub.2MnO.sub.3.(1-x)LiMn.sub.2-yM.sub.yO.sub.4 for 0electrode is activated by removing lithia, or lithium and lithia, from the precursor. A cell and battery are also disclosed incorporating the disclosed positive electrode.

  11. A new composite electrode architecture for energy storage devices

    NASA Technical Reports Server (NTRS)

    Ferro, Richard E.; Swain, Greg M.; Tatarchuk, B. J.

    1992-01-01

    The research objective is to determine how the electrode microstructure (architecture) affect the performance of the nickel hydroxide electrochemical system. It was found that microstructure and additional surface area makes a difference. The best architectures are the FIBREX/nickel and nickel fiber composite electrodes. The conditioning time for full utilization was greatly reduced. The accelerated increase in capacity vs. cycling appears to be a good indicator of the condition of the electrode/active material microstructure and morphology. Conformal deposition of the active material may be indicated and important. Also higher utilizations were obtained; greater than 80 pct. after less than 5 cycles and greater than 300 pct. after more than 5 cycles using nickel fiber composite electrode assuming a 1 electron transfer per equivalent.

  12. Towards uniformly dispersed battery electrode composite materials: Characteristics and performance

    SciTech Connect

    Yo Han Kwon; Takeuchi, Esther S.; Huie, Matthew M.; Choi, Dalsu; Chang, Mincheol; Marschilok, Amy C.; Takeuchi, Kenneth J.; Reichmanis, Elsa

    2016-01-14

    Battery electrodes are complex mesoscale systems comprised of electroactive components, conductive additives, and binders. In this report, methods for processing electrodes with dispersion of the components are described. To investigate the degree of material dispersion, a spin-coating technique was adopted to provide a thin, uniform layer that enabled observation of the morphology. Distinct differences in the distribution profile of the electrode components arising from individual materials physical affinities were readily identified. Hansen solubility parameter (HSP) analysis revealed pertinent surface interactions associated with materials dispersivity. Further studies demonstrated that HSPs can provide an effective strategy to identify surface modification approaches for improved dispersions of battery electrode materials. Specifically, introduction of surfactantlike functionality such as oleic acid (OA) capping and P3HT-conjugated polymer wrapping on the surface of nanomaterials significantly enhanced material dispersity over the composite electrode. The approach to the surface treatment on the basis of HSP study can facilitate design of composite electrodes with uniformly dispersed morphology and may contribute to enhancing their electrical and electrochemical behaviors. The conductivity of the composites and their electrochemical performance was also characterized. In conclusion, the study illustrates the importance of considering electronic conductivity, electron transfer, and ion transport in the design of environments incorporating active nanomaterials.

  13. Towards uniformly dispersed battery electrode composite materials: Characteristics and performance

    DOE PAGES

    Yo Han Kwon; Takeuchi, Esther S.; Huie, Matthew M.; ...

    2016-01-14

    Battery electrodes are complex mesoscale systems comprised of electroactive components, conductive additives, and binders. In this report, methods for processing electrodes with dispersion of the components are described. To investigate the degree of material dispersion, a spin-coating technique was adopted to provide a thin, uniform layer that enabled observation of the morphology. Distinct differences in the distribution profile of the electrode components arising from individual materials physical affinities were readily identified. Hansen solubility parameter (HSP) analysis revealed pertinent surface interactions associated with materials dispersivity. Further studies demonstrated that HSPs can provide an effective strategy to identify surface modification approaches formore » improved dispersions of battery electrode materials. Specifically, introduction of surfactantlike functionality such as oleic acid (OA) capping and P3HT-conjugated polymer wrapping on the surface of nanomaterials significantly enhanced material dispersity over the composite electrode. The approach to the surface treatment on the basis of HSP study can facilitate design of composite electrodes with uniformly dispersed morphology and may contribute to enhancing their electrical and electrochemical behaviors. The conductivity of the composites and their electrochemical performance was also characterized. In conclusion, the study illustrates the importance of considering electronic conductivity, electron transfer, and ion transport in the design of environments incorporating active nanomaterials.« less

  14. Toward Uniformly Dispersed Battery Electrode Composite Materials: Characteristics and Performance.

    PubMed

    Kwon, Yo Han; Huie, Matthew M; Choi, Dalsu; Chang, Mincheol; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S; Reichmanis, Elsa

    2016-02-10

    Battery electrodes are complex mesoscale systems comprised of electroactive components, conductive additives, and binders. In this report, methods for processing electrodes with dispersion of the components are described. To investigate the degree of material dispersion, a spin-coating technique was adopted to provide a thin, uniform layer that enabled observation of the morphology. Distinct differences in the distribution profile of the electrode components arising from individual materials physical affinities were readily identified. Hansen solubility parameter (HSP) analysis revealed pertinent surface interactions associated with materials dispersivity. Further studies demonstrated that HSPs can provide an effective strategy to identify surface modification approaches for improved dispersions of battery electrode materials. Specifically, introduction of surfactantlike functionality such as oleic acid (OA) capping and P3HT-conjugated polymer wrapping on the surface of nanomaterials significantly enhanced material dispersity over the composite electrode. The approach to the surface treatment on the basis of HSP study can facilitate design of composite electrodes with uniformly dispersed morphology and may contribute to enhancing their electrical and electrochemical behaviors. The conductivity of the composites and their electrochemical performance was also characterized. The study illustrates the importance of considering electronic conductivity, electron transfer, and ion transport in the design of environments incorporating active nanomaterials.

  15. Ionic polymer metal composites with nanoporous carbon electrodes

    NASA Astrophysics Data System (ADS)

    Palmre, Viljar; Brandell, Daniel; Mäeorg, Uno; Torop, Janno; Volobujeva, Olga; Punning, Andres; Johanson, Urmas; Aabloo, Alvo

    2010-04-01

    Ionic Polymer Metal Composites (IPMCs) are soft electroactive polymer materials that bend in response to the voltage stimulus (1 - 4 V). They can be used as actuators or sensors. In this paper, we introduce two new highly-porous carbon materials for assembling high specific area electrodes for IPMC actuators and compare their electromechanical performance with recently reported IPMCs based on RuO2 electrodes. We synthesize ionic liquid (Emi-Tf) actuators with either Carbide-Derived Carbon (CDC) (derived from TiC) or coconut shell based activated carbon electrodes. The carbon electrodes are applied onto ionic liquid-swollen Nafion membranes using the direct assembly process. Our results show that actuators assembled with CDC electrodes have the greatest peak-to-peak strain output, reaching up to 20.4 mɛ (equivalent to >2%) at a 2 V actuation signal, exceeding that of the RuO2 electrodes by more than 100%. The electrodes synthesized from TiC-derived carbon also revealed significantly higher maximum strain rate. The differences between the materials are discussed in terms of molecular interactions and mechanisms upon actuation in the different electrodes.

  16. Air electrode composition for solid oxide fuel cell

    DOEpatents

    Kuo, L.; Ruka, R.J.; Singhal, S.C.

    1999-08-03

    An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO{sub 3}. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell. 3 figs.

  17. Air electrode composition for solid oxide fuel cell

    DOEpatents

    Kuo, Lewis; Ruka, Roswell J.; Singhal, Subhash C.

    1999-01-01

    An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO.sub.3. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell.

  18. Nanothorn electrodes for ionic polymer-metal composite artificial muscles

    NASA Astrophysics Data System (ADS)

    Palmre, Viljar; Pugal, David; Kim, Kwang J.; Leang, Kam K.; Asaka, Kinji; Aabloo, Alvo

    2014-08-01

    Ionic polymer-metal composites (IPMCs) have recently received tremendous interest as soft biomimetic actuators and sensors in various bioengineering and human affinity applications, such as artificial muscles and actuators, aquatic propulsors, robotic end-effectors, and active catheters. Main challenges in developing biomimetic actuators are the attainment of high strain and actuation force at low operating voltage. Here we first report a nanostructured electrode surface design for IPMC comprising platinum nanothorn assemblies with multiple sharp tips. The newly developed actuator with the nanostructured electrodes shows a new way to achieve highly enhanced electromechanical performance over existing flat-surfaced electrodes. We demonstrate that the formation and growth of the nanothorn assemblies at the electrode interface lead to a dramatic improvement (3- to 5-fold increase) in both actuation range and blocking force at low driving voltage (1-3 V). These advances are related to the highly capacitive properties of nanothorn assemblies, increasing significantly the charge transport during the actuation process.

  19. Processing of carbon composite paper as electrode for fuel cell

    NASA Astrophysics Data System (ADS)

    Mathur, R. B.; Maheshwari, Priyanka H.; Dhami, T. L.; Sharma, R. K.; Sharma, C. P.

    The porous carbon electrode in a fuel cell not only acts as an electrolyte and a catalyst support, but also allows the diffusion of hydrogen fuel through its fine porosity and serves as a current-carrying conductor. A suitable carbon paper electrode is developed and possesses the characteristics of high porosity, permeability and strength along with low electrical resistivity so that it can be effectively used in proton-exchange membrane and phosphoric acid fuel cells. The electrode is prepared through a combination of two important techniques, viz., paper-making technology by first forming a porous chopped carbon fibre preform, and composite technology using a thermosetting resin matrix. The study reveals an interdependence of one parameter on another and how judicious choice of the processing conditions are necessary to achieve the desired characteristics. The current-voltage performance of the electrode in a unit fuel cell matches that of a commercially-available material.

  20. Method for uniformly distributing carbon flakes in a positive electrode, the electrode made thereby and compositions

    DOEpatents

    Mrazek, Franklin C.; Smaga, John A.; Battles, James E.

    1983-01-01

    A positive electrode for a secondary electrochemical cell wherein an electrically conductive current collector is in electrical contact with a particulate mixture of gray cast iron and an alkali metal sulfide and an electrolyte including alkali metal halides or alkaline earth metal halides. Also present may be a transition metal sulfide and graphite flakes from the conversion of gray cast iron to iron sulfide. Also disclosed is a method of distributing carbon flakes in a cell wherein there is formed an electrochemical cell of a positive electrode structure of the type described and a suitable electrolyte and a second electrode containing a material capable of alloying with alkali metal ions. The cell is connected to a source of electrical potential to electrochemically convert gray cast iron to an iron sulfide and uniformly to distribute carbon flakes formerly in the gray cast iron throughout the positive electrode while forming an alkali metal alloy in the negative electrode. Also disclosed are compositions useful in preparing positive electrodes.

  1. Removable Large-Area Ultrasmooth Silver Nanowire Transparent Composite Electrode.

    PubMed

    Jin, Yunxia; Wang, Kaiqing; Cheng, Yuanrong; Pei, Qibing; Xu, Yuxi; Xiao, Fei

    2017-02-08

    In this work, a composite silver nanowire (AgNW) transparent electrode that is large-area ultrasmooth without conductivity or transmittance scarifice, removable but with good resistance to both water and organic solvent, is reported. Via a simple low-temperature solution process without complicated transfer steps or additional pressure pressing, a new kind of AgNWs composite with biocompatible and patternable chitosan polymer complex demonstrates a quite low root-mean-square roughness ∼7 nm at a largest reported scan size of 50 μm × 50 μm, which is among the best flat surface. After long-term exposure to both water and organic solvent, it still shows strong adhesion, unchanged transparency, and no obvious conductivity reduction, suggesting a good stability staying on the substrate. Meanwhile, the polymer and silver nanowire in the composite electrode can be damaged via the same process through concentrated acid or base etching to leave off the substrate, allowing a simple patterning technology. Besides, the imported insulating polymer does not lower down the opto-electrical performance, and a high figure of merit close to 300 is obtained for the composite electrode, significantly outperforming the optoelectronic performance of indium-tin oxide (ITO) coated plastics (∼100) and comparable to ITO-coated glass. It shows great advantage to replace ITO as a promising transparent electrode.

  2. Temperature induced compositional redistribution in blended insertion electrodes

    NASA Astrophysics Data System (ADS)

    Heubner, C.; Lämmel, C.; Schneider, M.; Michaelis, A.

    2017-03-01

    Blending insertion compounds is a novel and promising approach to design advanced electrodes for future lithium-ion batteries. In spite of the considerable improvements regarding safety issues and power density, the understanding of basic interactions between the constituents of the blend and differences towards common single compound insertion electrodes is still ongoing. Herein we explore and verify the effect of temperature induced compositional redistribution of lithium-ions between the constituents of a blended insertion electrode for the first time. A model-like blend electrode and a special experimental setup is used to measure the compositional redistribution current between the constituents when subjected to a temperature change. The amount of lithium exchanged between the constituents of the blend is also derived theoretically based on the thermodynamic properties of the pure constituents, showing excellent agreement to the experimental results. Theoretical and experimental results proof that significant amounts of lithium are exchanged between the constituents without any cycling of the battery, suggesting that this effect may intrinsically reduce the cycle life of batteries with blended insertion electrodes.

  3. New reusable elastomer electrodes for assessing body composition

    NASA Astrophysics Data System (ADS)

    Moreno, M.-V.; Chaset, L.; Bittner, P. A.; Barthod, C.; Passard, M.

    2013-04-01

    The development of telemedicine requires finding solutions of reusable electrodes for use in patients' homes. The objective of this study is to evaluate the relevance of reusable elastomer electrodes for measuring body composition. We measured a population of healthy Caucasian (n = 17). A measurement was made with a reference device, the Xitron®, associated with AgCl Gel electrodes (Gel) and another measurement with a multifrequency impedancemeter Z-Metrix® associated with reusable elastomer electrodes (Elast). We obtained a low variability with an average error of repeatability of 0.39% for Re and 0.32% for Rinf. There is a non significantly difference (P T-test > 0.1) about 200 ml between extracellular water Ve measured with Gel and Elast in supine and in standing position. For total body water Vt, we note a non significantly difference (P T-test > 0.1) about 100 ml and 2.2 1 respectively in supine and standing position. The results give low dispersion, with R2 superior to 0.90, with a 1.5% maximal error between Gel and Elast on Ve in standing position. It looks possible, taking a few precautions, using elastomer electrodes for assessing body composition.

  4. CoS-Graphene Composite Counter Electrode for High Performance Dye-Sensitized Solar Cell.

    PubMed

    Wang, Fen; Wu, Congcong; Tan, Yuan; Jin, Tetsuro; Chi, Bo; Pu, Jian; Jian, Li

    2015-02-01

    CoS-graphene composite counter electrode for dye-sensitized solar cell (DSSC) was prepared by coating hydrothermal synthesized CoS with graphene onto the FTO conductive glass. SEM shows that CoS particles are uniformly dispersed in the graphene. The result confirms that the prepared composite counter electrode is of highly electrocatalytic activity towards iodine reduction, which is even better than Pt electrode. And cyclic voltammetry measurement also shows that the composite counter electrode has good stability after 100 scan cycles. DSSC with CoS-graphene as composite counter electrode achieves a maximum power conversion efficiency of 6.31%, which is better than Pt electrode.

  5. Infiltrated composite electrodes for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Buyukaksoy, Aligul

    Solid oxide fuel cells (SOFCs) are electrochemical devices which can convert chemical energy to electrical energy with efficiencies up to 60%. In order for SOFCs to be favorable energy conversion devices, the power obtained from a unit volume should be improved. This corresponds to minimized resistances from SOFC components (composite electrodes and electrolyte). Stability of the generated power is another important issue. Degradation of SOFCs with time due to microstructural processes or chemical reactions that occur at operating conditions; and due to reduction/oxidation cycles caused by the changes in the anode has been an important obstacle that has prevented the widespread commercial use of SOFCs. In this dissertation, the electrochemical properties of SOFC electrodes prepared by an infiltration technique were investigated. The long-term behavior and redox stability of the electrodes were evaluated individually and in the form of complete SOFCs. Interpretation of impedance spectra was used extensively to gain some fundamental understanding of the electrochemical properties of the electrodes along with voltammetry. Microstructural characterization was performed by electron microscopy techniques. LSM-YSZ cathodes prepared by polymeric LSM precursor infiltration resulted in cathode polarization resistance of 0.022 Ohm.cm2 at 800 °C, which then increased to 0.035 Ohm.cm2 and remained stable at this value for 100 hours. SOFCs with Ni-YSZ anodes and LSM-YSZ cathodes prepared by infiltration yielded total electrode polarizations of 0.080 Ohm.cm 2 at 800 °C. The electrode polarization resistances showed no degradation with time or upon redox cycling

  6. High surface area, low weight composite nickel fiber electrodes

    NASA Technical Reports Server (NTRS)

    Johnson, Bradley A.; Ferro, Richard E.; Swain, Greg M.; Tatarchuk, Bruce J.

    1993-01-01

    The energy density and power density of light weight aerospace batteries utilizing the nickel oxide electrode are often limited by the microstructures of both the collector and the resulting active deposit in/on the collector. Heretofore, these two microstructures were intimately linked to one another by the materials used to prepare the collector grid as well as the methods and conditions used to deposit the active material. Significant weight and performance advantages were demonstrated by Britton and Reid at NASA-LeRC using FIBREX nickel mats of ca. 28-32 microns diameter. Work in our laboratory investigated the potential performance advantages offered by nickel fiber composite electrodes containing a mixture of fibers as small as 2 microns diameter (Available from Memtec America Corporation). These electrode collectors possess in excess of an order of magnitude more surface area per gram of collector than FIBREX nickel. The increase in surface area of the collector roughly translates into an order of magnitude thinner layer of active material. Performance data and advantages of these thin layer structures are presented. Attributes and limitations of their electrode microstructure to independently control void volume, pore structure of the Ni(OH)2 deposition, and resulting electrical properties are discussed.

  7. Nanothorn electrodes for ionic polymer-metal composite artificial muscles.

    PubMed

    Palmre, Viljar; Pugal, David; Kim, Kwang J; Leang, Kam K; Asaka, Kinji; Aabloo, Alvo

    2014-08-22

    Ionic polymer-metal composites (IPMCs) have recently received tremendous interest as soft biomimetic actuators and sensors in various bioengineering and human affinity applications, such as artificial muscles and actuators, aquatic propulsors, robotic end-effectors, and active catheters. Main challenges in developing biomimetic actuators are the attainment of high strain and actuation force at low operating voltage. Here we first report a nanostructured electrode surface design for IPMC comprising platinum nanothorn assemblies with multiple sharp tips. The newly developed actuator with the nanostructured electrodes shows a new way to achieve highly enhanced electromechanical performance over existing flat-surfaced electrodes. We demonstrate that the formation and growth of the nanothorn assemblies at the electrode interface lead to a dramatic improvement (3- to 5-fold increase) in both actuation range and blocking force at low driving voltage (1-3 V). These advances are related to the highly capacitive properties of nanothorn assemblies, increasing significantly the charge transport during the actuation process.

  8. Protein interference with ion-selective electrode measurement depends on reference electrode composition and design.

    PubMed

    Payne, R B; Buckley, B M; Rawson, K M

    1991-01-01

    There is controversy about whether protein interferes with ion measurements using ion-selective electrodes. We have investigated the effects of changes in the salt-bridge composition of five commercially available analysers with open, membrane-restricted or porous frit-restricted reference electrode junctions on measurements of an albumin solution prepared by gel filtration. When the manufacturers' salt bridges were used, instruments with open or membrane-restricted junctions showed apparent increases in the activity of ionized calcium, sodium and potassium in the presence of protein. When the hypertonic bridge solutions were replaced with 150 mmol/L potassium chloride this increase disappeared. The instrument with a porous frit-restricted junction showed no protein effect, but its response to changes in sample sodium chloride concentration in protein-free solution suggested that its junction was functionally equivalent to that formed with an isotonic sodium chloride bridge. Our results emphasize that liquid junction design and composition affect ion measurements in protein-containing solutions and suggest that the use of hypertonic bridge solutions for biological samples needs to be re-examined.

  9. A Nanoporous Carbon/Exfoliated Graphite Composite For Supercapacitor Electrodes

    NASA Astrophysics Data System (ADS)

    Rosi, Memoria; Ekaputra, Muhamad P.; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal

    2010-12-01

    Nanoporous carbon was prepared from coconut shells using a simple heating method. The nanoporous carbon is subjected to different treatments: without activation, activation with polyethylene glycol (PEG), and activation with sodium hydroxide (NaOH)-PEG. The exfoliated graphite was synthesized from graphite powder oxidized with zinc acetate (ZnAc) and intercalated with polyvinyl alcohol (PVA) and NaOH. A composite was made by mixing the nanoporous carbon with NaOH-PEG activation, the exfoliated graphite and a binder of PVA solution, grinding the mixture, and annealing it using ultrasonic bath for 1 hour. All of as-synthesized materials were characterized by employing a scanning electron microscope (SEM), a MATLAB's image processing toolbox, and an x-ray diffractometer (XRD). It was confirmed that the composite is crystalline with (002) and (004) orientations. In addition, it was also found that the composite has a high surface area, a high distribution of pore sizes less than 40 nm, and a high porosity (67%). Noting that the pore sizes less than 20 nm are significant for ionic species storage and those in the range of 20 to 40 nm are very accessible for ionic clusters mobility across the pores, the composite is a promising material for the application as supercapacitor electrodes.

  10. Effects of the electrolyte composition on the electrode characteristics of rechargeable lithium batteries

    SciTech Connect

    Morita, Masayuki; Ishikawa, Masashi; Matsuda, Yoshiharu

    1995-12-31

    A variety of organic solvent-based electrolytes have been studied for ambient temperature, rechargeable lithium (ion) batteries. The ionic behavior of the electrolyte system was investigated through conductivity measurements. The electrochemical characteristics of carbon-based materials (carbon fiber and graphite) as the negative electrode were examined in different compositions of the organic electrolytes. The electrolyte composition as well as the structure of the electrode material greatly influenced the charge/discharge profiles of the electrode.

  11. Copper-decorated carbon nanotubes-based composite electrodes for nonenzymatic detection of glucose

    PubMed Central

    2012-01-01

    The aim of this study was to prepare three types of multiwall carbon nanotubes (CNT)-based composite electrodes and to modify their surface by copper electrodeposition for nonenzymatic oxidation and determination of glucose from aqueous solution. Copper-decorated multiwall carbon nanotubes composite electrode (Cu/CNT-epoxy) exhibited the highest sensitivity to glucose determination. PMID:22616801

  12. Compliant silver nanowire-polymer composite electrodes for bistable large strain actuation.

    PubMed

    Yun, Sungryul; Niu, Xiaofan; Yu, Zhibin; Hu, Weili; Brochu, Paul; Pei, Qibing

    2012-03-08

    A new compliant electrode-based on silver nanowire-polymer composite has been developed. The composite electrode has low sheet resistance (as low as 10 Ω/sq), remains conductive (10(2) -10(3) Ω/sq) at strains as high as 140%, and can support Joule heating. The combination of the composite and a bistable electroactive polymer produces electrically-induced, large-strain actuation and relaxation, reversibly without the need of mechanical programming.

  13. Aqueous processing of composite lithium ion electrode material

    DOEpatents

    Li, Jianlin; Armstrong, Beth L; Daniel, Claus; Wood, III, David L

    2015-02-17

    A method of making a battery electrode includes the steps of dispersing an active electrode material and a conductive additive in water with at least one dispersant to create a mixed dispersion; treating a surface of a current collector to raise the surface energy of the surface to at least the surface tension of the mixed dispersion; depositing the dispersed active electrode material and conductive additive on a current collector; and heating the coated surface to remove water from the coating.

  14. Three-Dimensional Adhesion Map Based on Surface and Interfacial Cutting Analysis System for Predicting Adhesion Properties of Composite Electrodes.

    PubMed

    Kim, Kyuman; Byun, Seoungwoo; Cho, Inseong; Ryou, Myung-Hyun; Lee, Yong Min

    2016-09-14

    Using a surface and interfacial cutting analysis system (SAICAS) that can measure the adhesion strength of a composite electrode at a specific depth from the surface, we can subdivide the adhesion strength of a composite electrode into two classes: (1) the adhesion strength between the Al current collector and the cathode composite electrode (FAl-Ca) and (2) the adhesion strength measured at the mid-depth of the cathode composite electrode (Fmid). Both adhesion strengths, FAl-Ca and Fmid, increase with increasing electrode density and loading level. From the SAICAS measurement, we obtain a mathematical equation that governs the adhesion strength of the composite electrodes. This equation revealed a maximum accuracy of 97.2% and 96.1% for FAl-Ca and Fmid, respectively, for four randomly chosen composite electrodes varying in electrode density and loading level.

  15. Composite LiFePO 4/AC high rate performance electrodes for Li-ion capacitors

    NASA Astrophysics Data System (ADS)

    Böckenfeld, N.; Kühnel, R.-S.; Passerini, S.; Winter, M.; Balducci, A.

    This manuscript reports the performance of composite electrodes based on the mixture of two, electrochemically active, materials: lithium iron phosphate (LiFePO 4) and activated carbon (AC). The sodium salt of carboxymethylcellulose (CMC) was used as binder to cast the composite electrodes out of aqueous slurries. The investigated electrodes display high specific capacity and high cycling stability. Upon constant current tests with a charge rate of 50C and a discharge rate of 1D, the electrodes display a capacity of ca. 70 mAh g -1 while 60 mAh g -1 are delivered during pulse sequence tests at 100C. These results indicate such electrodes as promising candidates for the realization of lithium-ion capacitors.

  16. Composition suitable for use as inert electrode having good electrical conductivity and mechanical properties

    DOEpatents

    Ray, Siba P.; Rapp, Robert A.

    1984-01-01

    An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily.

  17. Composition suitable for use as inert electrode having good electrical conductivity and mechanical properties

    DOEpatents

    Ray, S.P.; Rapp, R.A.

    1984-06-12

    An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily. 8 figs.

  18. Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids

    PubMed Central

    2011-01-01

    The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode. PMID:21711910

  19. New tetradecyltrimethylammonium-selective electrodes: surface composition and topography as correlated with electrode's life span.

    PubMed

    Marafie, Hayat M; Al-Shammari, Tahani F; Shoukry, Adel F

    2012-03-15

    Two conventional plastic membrane electrodes that are selective for the tetradecyltrimethylammonium cation (TTA) have been prepared. The ion exchangers of these sensors were the ion associate, TTA-PT, and the ion aggregate, TTA-PSS, where PT and PSS are phosphotungstate and polystyrene sulfonate, respectively. The following performance characteristics of the TTA-PT- and TTA-PSS-containing electrodes were found: conditioning time of 30 and 20 min; potential response of 58.2 and 61.1 mV/TTA concentration decade; rectilinear concentration ranges of 2.0 × 10(-5)-5.0 × 10(-2) and 1.5 × 10(-5)-7.9 × 10(-2) mol L(-1); average working pH ranges of 4.0-10.5 and 3.8-10.7; life spans of 20 and 28 weeks, and isothermal temperature coefficients of 4.44 × 10(-4) and 6.10 × 10(-4)V/°C, respectively. Both electrodes exhibited high selectivity for TTA with an increasing number of inorganic and quaternary ammonium surfactant cations. These electrodes have been successfully applied to assay an antiseptic formulation containing TTA. Surface analyses using electron microscopy and X-ray photoelectron spectroscopy were used to determine the cause of the limited life span of plastic membrane electrodes.

  20. Metal/Diamond Composite Thin-Film Electrodes: New Carbon Supported Catalytic Electrodes

    SciTech Connect

    Greg M. Swain, PI

    2009-03-10

    The DOE-funded research conducted by the Swain group was focused on (i) understanding structure-function relationships at boron-doped diamond thin-film electrodes, (ii) understanding metal phase formation on diamond thin films and developing electrochemical approaches for producing highly dispersed electrocatalyst particles (e.g., Pt) of small nominal particle size, (iii) studying the electrochemical activity of the electrocatalytic electrodes for hydrogen oxidation and oxygen reduction and (iv) conducting the initial synthesis of high surface area diamond powders and evaluating their electrical and electrochemical properties when mixed with a Teflon binder. (Note: All potentials are reported versus Ag/AgCl (sat'd KCl) and cm{sup 2} refers to the electrode geometric area, unless otherwise stated).

  1. Composite Metal-hydrogen Electrodes for Metal-Hydrogen Batteries

    SciTech Connect

    Ruckman, M W; Wiesmann, H; Strongin, M; Young, K; Fetcenko, M

    1997-04-01

    The purpose of this project is to develop and conduct a feasibility study of metallic thin films (multilayered and alloy composition) produced by advanced sputtering techniques for use as anodes in Ni-metal hydrogen batteries. The anodes could be incorporated in thin film solid state Ni-metal hydrogen batteries that would be deposited as distinct anode, electrolyte and cathode layers in thin film devices. The materials could also be incorporated in secondary consumer batteries (i.e. type AF(4/3 or 4/5)) which use electrodes in the form of tapes. The project was based on pioneering studies of hydrogen uptake by ultra-thin Pd-capped metal-hydrogen ratios exceeding and fast hydrogen charging and Nb films, these studies suggested that materials with those of commercially available metal hydride materials discharging kinetics could be produced. The project initially concentrated on gas phase and electrochemical studies of Pd-capped niobium films in laboratory-scale NiMH cells. This extended the pioneering work to the wet electrochemical environment of NiMH batteries and exploited advanced synchrotron radiation techniques not available during the earlier work to conduct in-situ studies of such materials during hydrogen charging and discharging. Although batteries with fast charging kinetics and hydrogen-metal ratios approaching unity could be fabricated, it was found that oxidation, cracking and corrosion in aqueous solutions made pure Nb films-and multiiayers poor candidates for battery application. The project emphasis shifted to alloy films based on known elemental materials used for NiMH batteries. Although commercial NiMH anode materials contain many metals, it was found that 0.24 µm thick sputtered Zr-Ni films cycled at least 50 times with charging efficiencies exceeding 95% and [H]/[M] ratios of 0.7-1.0. Multilayered or thicker Zr-Ni films could be candidates for a thin film NiMH battery that may have practical applications as an integrated power source for

  2. Effects of reversible chemical reaction on Li diffusion and stresses in spherical composition-gradient electrodes

    SciTech Connect

    Li, Yong; Zhang, Kai; Zheng, Bailin Zhang, Xiaoqian; Wang, Qi

    2015-06-28

    Composition-gradient electrode materials have been proven to be one of the most promising materials in lithium-ion battery. To study the mechanism of mechanical degradation in spherical composition-gradient electrodes, the finite deformation theory and reversible chemical theory are adopted. In homogeneous electrodes, reversible electrochemical reaction may increase the magnitudes of stresses. However, reversible electrochemical reaction has different influences on stresses in composition-gradient electrodes, resulting from three main inhomogeneous factors—forward reaction rate, backward reaction rate, and reaction partial molar volume. The decreasing transition form of forward reaction rate, increasing transition form of backward reaction rate, and increasing transition form of reaction partial molar volume can reduce the magnitudes of stresses. As a result, capacity fading and mechanical degradation are reduced by taking advantage of the effects of inhomogeneous factors.

  3. Arsenic removal from groundwater using low-cost carbon composite electrodes for capacitive deionization.

    PubMed

    Lee, Ju-Young; Chaimongkalayon, Nantanee; Lim, Jinho; Ha, Heung Yong; Moon, Seung-Hyeon

    2016-01-01

    Affordable carbon composite electrodes were developed to treat low-concentrated groundwater using capacitive deionization (CDI). A carbon slurry prepared using activated carbon powder (ACP), poly(vinylidene fluoride), and N-methyl-2-pyrrolidone was employed as a casting solution to soak in a low-cost porous substrate. The surface morphology of the carbon composite electrodes was investigated using a video microscope and scanning electron microscopy. The capacitance and electrical conductivity of the carbon composite electrodes were then examined using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. According to the CV and EIS measurements, the capacitances and electrical conductivities of the carbon composite electrodes were in the range of 8.35-63.41 F g(-1) and 0.298-0.401 S cm(-1), respectively, depending on ACP contents. A CDI cell was assembled with the carbon composite electrodes instead of with electrodes and current collectors. The arsenate removal test included an investigation of the optimization of several important operating parameters, such as applied voltage and solution pH, and it achieved 98.8% removal efficiency using a 1 mg L(-1) arsenate solution at a voltage of 2 V and under a pH 9 condition.

  4. Spray-Coated Multiwalled Carbon Nanotube Composite Electrodes for Thermal Energy Scavenging Electrochemical Cells.

    PubMed

    Holubowitch, Nicolas E; Landon, James; Lippert, Cameron A; Craddock, John D; Weisenberger, Matthew C; Liu, Kunlei

    2016-08-31

    Spray-coated multiwalled carbon nanotube/poly(vinylidene fluoride) (MWCNT/PVDF) composite electrodes, scCNTs, with varying CNT compositions (2 to 70 wt %) are presented for use in a simple thermal energy-scavenging cell (thermocell) based on the ferro/ferricyanide redox couple. Their utility for direct thermal-to-electrical energy conversion is explored at various temperature differentials and cell orientations. Performance is compared to that of buckypaper, a 100% CNT sheet material used as a benchmark electrode in thermocell research. The 30 to 70 wt % scCNT composites give the highest power output by electrode area-seven times greater than buckypaper at ΔT = 50 °C. CNT utilization is drastically enhanced in our electrodes, reaching 1 W gCNT(-1) compared to 0.036 W gCNT(-1) for buckypaper. Superior performance of our spray-coated electrodes is attributed to both wettability with better use of a large portion of electrochemically active CNTs and minimization of ohmic and thermal contact resistances. Even composites with as low as 2 wt % CNTs are still competitive with prior art. The MWCNT/PVDF composites developed herein are inexpensive, scalable, and serve a general need for CNT electrode optimization in next-generation devices.

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

    DOEpatents

    Rieke, Peter C.; Coffey, Gregory W.; Pederson, Larry R.; Marina, Olga A.; Hardy, John S.; Singh, Prabhaker; Thomsen, Edwin C.

    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.

  6. Polyacrylate microspheres composite for all-solid-state reference electrodes.

    PubMed

    Kisiel, Anna; Donten, Mikołaj; Mieczkowski, Józef; Rius-Ruiz, F Xavier; Maksymiuk, Krzysztof; Michalska, Agata

    2010-09-01

    A novel concept is proposed for the encapsulation of components within polyacrylate microspheres, prior to their incorporation into a membrane phase. Thus finer and better controlled dispersion of heterogeneous membrane components can be achieved. This concept was verified by using a poly(n-butyl acrylate) membrane-based reference electrode as an example. In this example the proper dispersion of solid constituents of the heterogeneous membrane and prevention of their leakage are both of primary importance. Potassium chloride-loaded poly(n-butyl acrylate) microspheres were prepared and then left in contact with silver nitrate to convert some of the KCl into AgCl. The material obtained was introduced into a poly(n-butyl acrylate) membrane. The reference electrode membranes obtained in this way were characterized with much more stable potential (both in different electrolytes and over time) compared with electrodes prepared by the direct introduction of KCl and AgCl to the membrane.

  7. A novel method of fabricating carbon nanotubes-polydimethylsiloxane composite electrodes for electrocardiography.

    PubMed

    Liu, Benyan; Chen, Yingmin; Luo, Zhangyuan; Zhang, Wenzan; Tu, Quan; Jin, Xun

    2015-01-01

    Polymer-based flexible electrodes are receiving much attention in medical applications due to their good wearing comfort. The current fabrication methods of such electrodes are not widely applied. In this study, polydimethylsiloxane (PDMS) and conductive additives of carbon nanotubes (CNTs) were employed to fabricate composite electrodes for electrocardiography (ECG). A three-step dispersion process consisting of ultrasonication, stirring, and in situ polymerization was developed to yield homogenous CNTs-PDMS mixtures. The CNTs-PDMS mixtures were used to fabricate CNTs-PDMS composite electrodes by replica technology. The influence of ultrasonication time and CNT concentration on polymer electrode performance was evaluated by impedance and ECG measurements. The signal amplitude of the electrodes prepared using an ultrasonication time of 12 h and CNT content of 5 wt% was comparable to that of commercial Ag/AgCl electrodes. The polymer electrodes were easily fabricated by conventional manufacturing techniques, indicating a potential advantage of reduced cost for mass production.

  8. Fast redox of composite electrode of nitroxide radical polymer and carbon with polyacrylate binder

    NASA Astrophysics Data System (ADS)

    Komaba, Shinichi; Tanaka, Tatsuya; Ozeki, Tomoaki; Taki, Takayuki; Watanabe, Hiroaki; Tachikawa, Hiroyuki

    For organic radical batteries, poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) has been reported as a promising positive electrode material. The PTMA/C composite electrode prepared with polyacrylate binder demonstrated the fast redox performance for the application to aprotic secondary batteries. When the variation in discharge capacities of the PTMA/C composite electrode was tested galvanostatically at 20 C rates, the electrode retained 96% of the initial capacity after 1000 cycles. This is attributed to the fact that the redox of PTMA is a simple reaction to form the oxoammonium salt doped with ClO 4 - anions in the electrolyte. When the PTMA/C composite electrode was discharged at different C rates, the electrode retained 81% of the theoretical capacity even at 50 C rates. This remarkably high rate capability originates from the fast electron-transfer kinetic of the 2,2,6,6-tetramethylpiperidine- N-oxyl (so-called TEMPO) radical, partially jelled polyacrylate binder, and the improved conductivity throughout the electrode by thoroughly mixing with carbon.

  9. Chemistry of carbon polymer composite electrode - An X-ray photoelectron spectroscopy study

    NASA Astrophysics Data System (ADS)

    Andersen, Shuang Ma; Dhiman, Rajnish; Skou, Eivind

    2015-01-01

    Surface chemistry of the electrodes in a proton exchange membrane fuel cell is of great importance for the cell performance. Many groups have reported that electrode preparation condition has a direct influence on the resulting electrode properties. In this work, the oxidation state of electrode components and the composites (catalyst ionomer mixtures) in various electrode structures were systematically studied with X-ray photoelectron spectroscopy (XPS). Based on the spectra, when catalyst is physically mixed with Nafion ionomer, the resulting electrode surface chemistry is a combination of the two components. When the electrode is prepared with a lamination procedure, the ratio between fluorocarbon and graphitic carbon is decreased. Moreover, ether type oxide content is decreased although carbon oxide is slightly increased. This indicates structure change of the catalyst layer due to an interaction between the ionomer and the catalyst and possible polymer structural change during electrode fabrication. The surface of micro porous layer was found to be much more influenced by the lamination, especially when it is in contact with catalysts in the interphase. Higher amount of platinum oxide was observed in the electrode structures (catalyst ionomer mixture) compared to the catalyst powder. This also indicates a certain interaction between the functional groups in the polymer and platinum surface.

  10. CNT/PDMS composite flexible dry electrodes for long-term ECG monitoring.

    PubMed

    Jung, Ha-Chul; Moon, Jin-Hee; Baek, Dong-Hyun; Lee, Jae-Hee; Choi, Yoon-Young; Hong, Joung-Sook; Lee, Sang-Hoon

    2012-05-01

    We fabricated a carbon nanotube (CNT)/ polydimethylsiloxane (PDMS) composite-based dry ECG electrode that can be readily connected to conventional ECG devices, and showed its long-term wearable monitoring capability and robustness to motion and sweat. While the dispersion of CNTs in PDMS is challenging, we optimized the process to disperse untreated CNTs within PDMS by mechanical force only. The electrical and mechanical characteristics of the CNT/PDMS electrode were tested according to the concentration of CNTs and its thickness. The performances of ECG electrodes were evaluated by using 36 types of electrodes which were fabricated with different concentrations of CNTs, and with a differing diameter and thickness. The ECG signals were obtained by using electrodes of diverse sizes to observe the effects of motion and sweat, and the proposed electrode was shown to be robust to both factors. The CNT concentration and diameter of the electrodes were critical parameters in obtaining high-quality ECG signals. The electrode was shown to be biocompatible from the cytotoxicity test. A seven-day continuous wearability test showed that the quality of the ECG signal did not degrade over time, and skin reactions such as itching or erythema were not observed. This electrode could be used for the long-term measurement of other electrical biosignals for ubiquitous health monitoring including EMG, EEG, and ERG.

  11. Magnetite nanoparticles-chitosan composite containing carbon paste electrode for glucose biosensor application.

    PubMed

    Kavitha, A L; Prabu, H Gurumallesh; Babu, S Ananda; Suja, S K

    2013-01-01

    This work was aimed to develop reusable magnetite chitosan composite containing carbon paste electrode for biosensor application. Glucose oxidase (GOx) enzyme was used to prepare GOx-magnetite-chitosan nanocomposite containing carbon paste electrode for sensitive detection of glucose. The immobilized enzyme retained its bioactivity, exhibited a surface confined reversible electron transfer reaction, and had good stability. The surface parameters like surface coverage (tau), Diffusion coefficient (D0), and rate constant (kS) were studied. The carbon paste modified electrode virtually eliminated the interference during the detection of glucose. The excellent performance of the biosensor is attributed to large surface-to-volume ratio, high conductivity and good biocompatibility of chitosan, which enhances the enzyme absorption and promotes electron transfer between redox enzymes and the surface of electrode. The shelf life of the developed electrode system is about 12 weeks under refrigerated conditions. We report for the first time in the fabrication of carbon paste bioelectrode containing magnetite-chitosan-GOx.

  12. Electrochemical oxidation of methanol on Pt nanoparticles composited MnO 2 nanowire arrayed electrode

    NASA Astrophysics Data System (ADS)

    Zhao, Guang-Yu; Li, Hu-Lin

    2008-03-01

    By use of the membrane-template synthesis route, MnO 2 nanowire arrayed electrodes are successfully synthesized by means of the anodic deposition technique. The Pt nanoparticles composited MnO 2 nanowire arrayed electrodes (PME) are obtained through depositing Pt on MnO 2 nanowire arrayed electrode by cathode deposition technique. For comparison of electrochemical performance, Pt nanowire arrayed electrodes which have the same amount of Pt with PME are also prepared. The electro-oxidation of methanol on PME and Pt nanowire arrayed electrodes is investigated at room temperature by cyclic voltammetry, which show that about 110 mV decreased overpotential and 2.1-fold enhanced votammetric current are achieved on PME. The chronoamperometry result demonstrates that the resistance to carbon monoxide for PME is improved.

  13. Selective and sensitive determination of dopamine by composites of polypyrrole and graphene modified electrodes.

    PubMed

    Si, Peng; Chen, Hailan; Kannan, Palanisamy; Kim, Dong-Hwan

    2011-12-21

    A novel method is developed to fabricate the polypyrrole (PPy) and graphene thin films on electrodes by electrochemical polymerization of pyrrole with graphene oxide (GO) as a dopant, followed by electrochemical reduction of GO in the composite film. The composite of PPy and electrochemically reduced graphene oxide (eRGO)-modified electrode is highly sensitive and selective toward the detection of dopamine (DA) in the presence of high concentrations of ascorbic acid (AA) and uric acid (UA). The sensing performance of the PPy/eRGO-modified electrode is investigated by differential pulse voltammetry (DPV), revealing a linear range of 0.1-150 μM with a detection limit of 23 nM (S/N = 3). The practical application of the PPy/eRGO-modified electrode is successfully demonstrated for DA determination in human blood serum.

  14. Electroadsorption desalination with carbon nanotube/PAN-based carbon fiber felt composites as electrodes.

    PubMed

    Liu, Yang; Zhou, Junbo

    2014-01-01

    The chemical vapor deposition method is used to prepare CNT (carbon nanotube)/PCF (PAN-based carbon fiber felt) composite electrodes in this paper, with the surface morphology of CNT/PCF composites and electroadsorption desalination performance being studied. Results show such electrode materials with three-dimensional network nanostructures having a larger specific surface area and narrower micropore distribution, with a huge number of reactive groups covering the surface. Compared with PCF electrodes, CNT/PCF can allow for a higher adsorption and desorption rate but lower energy consumption; meanwhile, under the condition of the same voltage change, the CNT/PCF electrodes are provided with a better desalination effect. The study also found that the higher the original concentration of the solution, the greater the adsorption capacity and the lower the adsorption rate. At the same time, the higher the solution's pH, the better the desalting; the smaller the ions' radius, the greater the amount of adsorption.

  15. Dispersion of nanocrystalline Fe3O4 within composite electrodes: Insights on battery-related electrochemistry

    DOE PAGES

    David C. Bock; Takeuchi, Kenneth J.; Pelliccione, Christopher J.; ...

    2016-04-20

    Aggregation of nanosized materials in composite lithium-ion-battery electrodes can be a significant factor influencing electrochemical behavior. In this study, aggregation was controlled in magnetite, Fe3O4, composite electrodes via oleic acid capping and subsequent dispersion in a carbon black matrix. A heat treatment process was effective in the removal of the oleic acid capping agent while preserving a high degree of Fe3O4 dispersion. Electrochemical testing showed that Fe3O4 dispersion is initially beneficial in delivering a higher functional capacity, in agreement with continuum model simulations. However, increased capacity fade upon extended cycling was observed for the dispersed Fe3O4 composites relative to themore » aggregated Fe3O4 composites. X-ray absorption spectroscopy measurements of electrodes post cycling indicated that the dispersed Fe3O4 electrodes are more oxidized in the discharged state, consistent with reduced reversibility compared with the aggregated sample. Higher charge-transfer resistance for the dispersed sample after cycling suggests increased surface-film formation on the dispersed, high-surface-area nanocrystalline Fe3O4 compared to the aggregated materials. Furthermore, this study provides insight into the specific effects of aggregation on electrochemistry through a multiscale view of mechanisms for magnetite composite electrodes.« less

  16. Electrode

    SciTech Connect

    Clere, T.M.

    1983-08-30

    A 3-dimensional electrode is disclosed having substantially coplanar and substantially flat portions and ribbon-like curved portions, said curved portions being symmetrical and alternating in rows above and below said substantially coplanar, substantially flat portions, respectively, and a geometric configuration presenting in one sectional aspect the appearance of a series of ribbon-like oblate spheroids interrupted by said flat portions and in another sectional aspect, 90/sup 0/ from said one aspect, the appearance of a square wave pattern.

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

    SciTech Connect

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

    2014-09-15

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

  18. [Research on treatment of high salt wastewater by the graphite and activated carbon fiber composite electrodes].

    PubMed

    Zhou, Gui-Zhong; Wang, Zhao-Feng; Wang, Xuan; Li, Wen-Qian; Li, Shao-Xiang

    2014-05-01

    High salinity wastewater is one of the difficulties in the field of wastewater treatment. As a new desalination technology, electrosorption technology has many advantages. This paper studied a new type of carbon-based electrodes, the graphite and activated carbon fiber composite electrodes. And the influencing factors of electrosorption and its desalination effect were investigated. The electrosorption device had optimal desalination effect when the voltage was 1. 6 V, the retention time was 60 min and the plate spacing was 1 cm. The graphite and activated carbon fiber composite electrodes were used to treat the black liquor of refined cotton and sodium copper chlorophyll wastewater to investigate its desalination effect. When the electrodes were used to treat the black liquor of refined cotton after acid treatment, the removal rate of conductivity and COD reached 58. 8% and 75. 6% respectively when 8 pairs of electrodes were used. And when the electrode was used to treat the sodium copper chlorophyll wastewater, the removal rate of conductivity and COD reached higher than 50. 0% and 13. 5% respectively when 6-8 pairs of electrodes were used.

  19. Shape-alterable and -recoverable graphene/polyurethane bi-layered composite film for supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Tai, Zhixin; Yan, Xingbin; Xue, Qunji

    2012-09-01

    In this paper, a graphene/shape-memory polyurethane (PU) composite film, used for a supercapacitor electrode, is fabricated by a simple bonding method. In the composite, formerly prepared graphene paper is closely bonded on the surface of the PU slice, forming a bi-layered composite film. Based on the good flexibility of graphene paper and the outstanding shape holding capacity of PU phase, the resulting composite film can be changed into various shapes. Also, the composite film shows excellent shape recovery ability. The graphene/PU composite film used as the electrode maintains a satisfactory electrochemical capacitance of graphene material and there is no decay in the specific capacitance after long-cycle testing, making it attractive for novel supercapacitors with special shapes and shape-memory ability.

  20. Studies on conducting polymer and conducting polymerinorganic composite electrodes prepared via a new cathodic polymerization method

    NASA Astrophysics Data System (ADS)

    Singh, Nikhilendra

    A novel approach for the electrodeposition of conducting polymers and conducting polymer-inorganic composite materials is presented. The approach shows that conducting polymers, such as polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) can be electrodeposited by the application of a cathodic bias that generates an oxidizing agent, NO+, via the in-situ reduction of nitrate anions. This new cathodic polymerization method allows for the deposition of PPy and PEDOT as three dimensional, porous films composed of spherical polymer particles. The method is also suitable for the co-deposition of inorganic species producing conducting polymer-inorganic composite electrodes. Such composites are used as high surface area electrodes in Li-ion batteries, electrochemical hydrogen evolution and in the development of various other conducting polymer-inorganic composite electrodes. New Sn-PPy and Sb-PPy composite electrodes where Sn and Sb nanoparticles are well dispersed among the PPy framework are reported. These structures allow for decreased stress during expansion and contraction of the active material (Sn, Sb) during the alloying and de-alloying processes of a Li-ion battery anode, significantly alleviating the loss of active material due to pulverization processes. The new electrochemical synthesis mechanism allows for the fabrication of Sn-PPy and Sb-PPy composite electrodes directly from a conducting substrate and eliminates the use of binding materials and conducting carbon used in modern battery anodes, which significantly simplifies their fabrication procedures. Platinum (Pt) has long been identified as the most efficient catalyst for electrochemical water splitting, while nickel (Ni) is a cheaper, though less efficient alternative to Pt. A new morphology of PPy attained via the aforementioned cathodic deposition method allows for the use of minimal quantities of Pt and Ni dispersed over a very high surface area PPy substrate. These composite electrodes

  1. Enhanced photoelectrocatalytic activity for dye degradation by graphene-titania composite film electrodes.

    PubMed

    Wang, Peifang; Ao, Yanhui; Wang, Chao; Hou, Jun; Qian, Jin

    2012-07-15

    Graphene-titania composite film electrodes have been fabricated by a dip-coating method. Transmission electron microscopy (TEM) images show that the titania nanoparticles were dispersed uniformly, with only a little aggregation on the surface and edges of the graphene sheets. XRD analysis showed that the composite electrodes comprised the anatase phase of titania with just a little rutile phase. The photoelectrocatalytic activities of the as-prepared samples were investigated by studies of the degradation of Reactive Brilliant Red dye X-3B (C.I. reactive red 2). An enhancement of the photocurrents was observed using the graphene-titania composite electrodes, compared with pure titania film electrodes, under UV light irradiation. This improvement is attributed to the following two reasons: enhanced migration efficiency of the photo-induced electrons and enhanced adsorption activity of the dye molecules. In addition, we investigated the effects of graphene content and pH values on the photoelectrocatalytic activity of the as-prepared composite film electrodes. Results showed that there was an optimal amount of 5% (initial graphite oxide content).

  2. Characterization of copper manganite oxide-polypyrrole composite electrodes cathodically polarized in acidic medium

    SciTech Connect

    Marco, J.F.; Canto, M. del; Rios, E.; Gautier, J.L.

    2008-08-04

    We have studied the electrochemical behaviour induced by polarization in sandwich-type composite electrodes with the structure GC/PPy/PPy(Ox)/PPy where GC stands for glassy carbon, PPy for polypyrrole and Ox for Cu{sub 1.4}Mn{sub 1.6}O{sub 4} nanoparticles. The electrodes were polarized at -0.45 V/SCE in 0.15 M KCl aqueous solution at pH 2.2 either saturated in Ar or O{sub 2} at 25 deg. C. The changes occurring on these electrodes were studied using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (EXAFS and XANES) techniques. In previous work we have shown that when the oxide particles are incorporated into the PPy matrix the Cu{sup +} present in the initial oxide suffers dismutation to give Cu{sup 2+} and metallic Cu. In this work we show that the polarized electrodes also reveal the presence of metallic Cu and Cu{sup 2+}. The data also show that the oxide particles embedded in the polarized electrodes contain Mn{sup 3+} and Mn{sup 4+}, although the Mn{sup 3+}/Mn{sup 4+} ratio is different from that found in the fresh electrodes. The Cl 2p XPS data show that in the electrode polarized in O{sub 2} there is an enhancement of the Cl covalent contribution that appears at 200.8 eV (which is already present in the fresh electrode although with a very small intensity). This result suggests that the oxygen reduction reaction leads to an increase of the OH{sup -} concentration inside the composite electrode that explains the charge transport in PPy at negative potentials.

  3. Poly(vinyl alcohol)/poly(vinyl chloride) composite polymer membranes for secondary zinc electrodes

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Yang, Jen Ming; Wu, Cheng-Yeou

    A microporous composite polymer membrane composed of poly(vinyl alcohol) (PVA) and poly(vinyl chloride) (PVC), was prepared by a solution casting method and a partial dissolution process. The characteristic properties of microporous PVA/PVC composite polymer membranes containing 2.5-10 wt.% PVC polymers as fillers were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), capillary flow porometry (CFP), micro-Raman spectroscopy, dynamic mechanical analyzer (DMA) and the AC impedance method. The electrochemical properties of a secondary Zn electrode with the PVA/PVC composite polymer membrane were studied using the galvanostatic charge/discharge method. The PVA/PVC composite polymer membrane showed good thermal, mechanical and electrochemical properties. As a result, the PVA/PVC composite polymer membrane appears to be a good candidate for use on the secondary Zn electrodes.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  5. Electrochemical Synthesis of Graphene/MnO2 Nano-Composite for Application to Supercapacitor Electrode.

    PubMed

    Jeong, Kwang Ho; Lee, Hyeon Jeong; Simpson, Michael F; Jeong, Mun

    2016-05-01

    Graphene/MnO2 nano-composite was electrochemically synthesized for application to an electrode material for electrochemical supercapacitors. The nanosized needle-like MnO2 was obtained by use of a graphene substrate. The prepared composite exhibited an ideal supercapacitive behavior. A capacitance retention of 94% was achieved with a 4 h deposition time (an initial capacitance of 574 mF/cm2 at a scan rate of 20 mV/s) and the retention declined with further deposition time. The results demonstrate enhanced contact between the electrode and electrolyte and improved power density as an electrochemical capacitor.

  6. Urea biosensor based on PANi(urease)-Nafion/Au composite electrode.

    PubMed

    Luo, Yung-Chien; Do, Jing-Shan

    2004-07-30

    The polyaniline (PANi)-Nafion composite film was prepared onto the ceramic plate by the cyclic voltammetry (CV) method with the various cycle numbers. When the PANi-Nafion/Au/ceramic plate with the preparing cycle number of 5 was as working electrode, the cathodic peak current was achieved as 84.0 microA in 60 mg dl(-1) NH4Cl buffer solution. On the other hand, the small cathodic peak currents for buffer solution in the presence of 60 mg dl(-1) LiOH, NaCl and KCl, respectively, were found with the same composite electrode as working electrode. The cathodic peak current decreased from 84.0 to 16.3 microA in the 60 mg dl(-1) NH4Cl buffer solution when the cycle number for preparing PANi-Nafion/Au/ceramic plate composite electrode with the CV method increased from 5 to 15. The enzyme of urease was immobilized onto the PANi-Nafion/Au/ceramic plate composite film by the electrochemical immobilization and the casting methods and used as sensing electrode to detect the concentration of urea in the buffer solution. The sensitivity of composite electrode immobilized with the casting method was greater than that of electrochemical immobilization method. The sensitivity and the detecting limit of the urea sensor were found to be 0.7 and 5.27 microA (mg dl(-1))(-1)cm(-2), as well as 6 and 0.3 mg dl(-1), respectively, when urease was immobilized by glutaraldehyde (GA) cross-linker and Nafion network, respectively.

  7. Superior lithium storage performance using sequentially stacked MnO2/reduced graphene oxide composite electrodes.

    PubMed

    Kim, Sue Jin; Yun, Young Jun; Kim, Ki Woong; Chae, Changju; Jeong, Sunho; Kang, Yongku; Choi, Si-Young; Lee, Sun Sook; Choi, Sungho

    2015-04-24

    Hybrid nanostructures based on graphene and metal oxides hold great potential for use in high-performance electrode materials for next-generation lithium-ion batteries. Herein, a new strategy to fabricate sequentially stacked α-MnO2 /reduced graphene oxide composites driven by surface-charge-induced mutual electrostatic interactions is proposed. The resultant composite anode exhibits an excellent reversible charge/discharge capacity as high as 1100 mA h g(-1) without any traceable capacity fading, even after 100 cycles, which leads to a high rate capability electrode performance for lithium ion batteries. Thus, the proposed synthetic procedures guarantee a synergistic effect of multidimensional nanoscale media between one (metal oxide nanowire) and two dimensions (graphene sheet) for superior energy-storage electrodes.

  8. Nanostructured carbon-metal oxide composite electrodes for supercapacitors: a review.

    PubMed

    Zhi, Mingjia; Xiang, Chengcheng; Li, Jiangtian; Li, Ming; Wu, Nianqiang

    2013-01-07

    This paper presents a review of the research progress in the carbon-metal oxide composites for supercapacitor electrodes. In the past decade, various carbon-metal oxide composite electrodes have been developed by integrating metal oxides into different carbon nanostructures including zero-dimensional carbon nanoparticles, one-dimensional nanostructures (carbon nanotubes and carbon nanofibers), two-dimensional nanosheets (graphene and reduced graphene oxides) as well as three-dimensional porous carbon nano-architectures. This paper has described the constituent, the structure and the properties of the carbon-metal oxide composites. An emphasis is placed on the synergistic effects of the composite on the performance of supercapacitors in terms of specific capacitance, energy density, power density, rate capability and cyclic stability. This paper has also discussed the physico-chemical processes such as charge transport, ion diffusion and redox reactions involved in supercapacitors.

  9. A new modified conducting carbon composite electrode as sensor for ascorbate and biosensor for glucose.

    PubMed

    Barsan, Madalina M; Brett, Christopher M A

    2009-09-01

    A new carbon-based conducting composite has been developed as electrochemical sensor and biosensor for the amperometric detection of ascorbate and glucose. Electrocatalytic oxidation of ascorbate has been done successfully at unmodified cellulose acetate-graphite composite electrodes, the sensor being highly sensitive, selective and with a low detection limit at 0.0 V vs. SCE and was successfully applied for ascorbate determination in commercial fruit juice samples. An interference free glucose biosensor has also been developed, based on the immobilisation of glucose oxidase by cross-linking with glutaraldehyde on poly (neutral red) modified composite electrodes. The biosensor exhibits a higher sensitivity of 31.5+/-1.7 microA cm(-2) mM(-1) than other carbon-composite-based glucose biosensors, a detection limit of 20.3 microM and a very short response time.

  10. Advanced 3D Ni(OH)2/CNT Gel Composite Electrodes for Supercapacitors

    NASA Astrophysics Data System (ADS)

    Cheng, Hanlin; Duong, Hai Minh

    2015-03-01

    In order to enhance the performance of supercapacitors, advanced 3D Porous CNT/Ni(OH)2 gel composite electrodes are developed in this work. Compared with previously reported graphene gel supercapacitors, our electrodes using 1D CNTs have smaller diffusion resistance due to a shorter ion transport path. The developed 3D xerogel composite electrodes demonstrate the success of a careful engineered guest/host materials interface. Initially, the CNT gels are coated on the nickel foam to form a 3D scaffold, which serves as a microscopic electrical conductive network. Then Ni(OH)2 are incorporated using a traditional electrodeposition method. In this work, two types of the 3D CNT-coated nickel foams are investigated. The gels can be used directly as hydrogels or dried in air to form xerogels. Both hydrogels and xerogels present 3D tangled CNT networks. It shows that the hydrogel composite electrodes with unbundled CNTs, though presenting high capacitances of 1400 F/g at low discharge rate, possess lower capacitances at higher discharge rate and a poor cycling performance of less than 23% retention. In contrast, the xerogel composite electrodes can overcome these limitations in terms of a satisfied discharge performance of 1200 F/g and a good cycling retention more than 85% due to a stronger Ni(OH)2/CNT interface. The CNT bundles in the xerogel electrodes formed during the drying process can give a flat surface with small curvature, which facilitate the Ni(OH)2 nucleation and growth. Thanks for the support from the A star R-265-000-424-305.

  11. Electrode material comprising graphene-composite materials in a graphite network

    DOEpatents

    Kung, Harold H.; Lee, Jung K.

    2014-07-15

    A durable electrode material suitable for use in Li ion batteries is provided. The material is comprised of a continuous network of graphite regions integrated with, and in good electrical contact with a composite comprising graphene sheets and an electrically active material, such as silicon, wherein the electrically active material is dispersed between, and supported by, the graphene sheets.

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

    PubMed

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

    2016-03-28

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

  13. Highly selective dopamine electrochemical sensor based on electrochemically pretreated graphite and nafion composite modified screen printed carbon electrode.

    PubMed

    Ku, Shuhao; Palanisamy, Selvakumar; Chen, Shen-Ming

    2013-12-01

    Herein, we report a highly selective dopamine electrochemical sensor based on electrochemically pretreated graphite/nafion composite modified screen printed carbon (SPC) electrode. Electrochemically activated graphite/nafion composite was prepared by using a simple electrochemical method. Scanning electron microscope (SEM) used to characterize the surface morphology of the fabricated composite electrode. The SEM result clearly indicates that the graphitic basal planes were totally disturbed and leads to the formation of graphite nanosheets. The composite modified electrode showed an enhanced electrocatalytic activity toward the oxidation of DA when compared with either electrochemical pretreated graphite or nafion SPC electrodes. The fabricated composite electrode exhibits a good electrocatalytic oxidation toward DA in the linear response range from 0.5 to 70 μM with the detection limit of 0.023 μM. The proposed sensor also exhibits very good selectivity and stability, with the appreciable sensitivity. In addition, the proposed sensor showed satisfactory recovery results toward the commercial pharmaceutical DA samples.

  14. Engineering study on TiSnSb-based composite negative electrode for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Wilhelm, H. A.; Marino, C.; Darwiche, A.; Soudan, P.; Morcrette, M.; Monconduit, L.; Lestriez, B.

    2015-01-01

    Micrometric TiSnSb is a promising negative electrode material for Li-ion batteries when formulated with carboxymethyl cellulose (CMC) binder and a mixture of carbon black and carbon nanofibers, and cycled in a fluoroethylene carbonate (FEC)-containing electrolyte. Here, other binder systems were evaluated, polyacrylic acid (PAAH) mixed with CMC, CMC in buffered solution at pH 3 and amylopectin. However CMC showed the better performance in terms of cycle life of the electrode. Whatever the binder, cycle life decreases with increasing the active mass loading, which is attributed to both the precipitation of liquid electrolyte degradation products and to the loss of electrical contacts within the composite electrode and with the current collector as a consequence of the active particles volume variations. Furthermore, calendaring the electrode unfortunately decreases the cycle life. The rate performance was studied as a function of the active mass loading and was shown to be determined by the electrode polarization resistance. Finally, full cells cycling tests with Li1Ni1/3Co1/3Mn1/3O2 at the positive electrode were done. 60% of the capacity is retained after 200 cycles at the surface capacity of 2.7 mAh cm-2.

  15. Carbon nanotube/polymer composite electrodes for flexible, attachable electrochemical DNA sensors.

    PubMed

    Li, Jianfeng; Lee, Eun-Cheol

    2015-09-15

    All-solution-processed, easily-made, flexible multi-walled carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS)-based electrodes were fabricated and used for electrochemical DNA sensors. These electrodes could serve as a recognition layer for DNA, without any surface modification, through π-π interactions between the MWCNTs and DNA, greatly simplifying the fabrication process for DNA sensors. The electrodes were directly connected to an electrochemical analyzer in the differential pulse voltammetry (DPV) and cyclic voltammetry (CV) measurements, where methylene blue was used as a redox indicator. Since neither functional groups nor probe DNA were immobilized on the surfaces of the electrodes, the sensor can be easily regenerated by washing these electrodes with water. The limit of detection was found to be 1.3 × 10(2)pM (S/N=3), with good DNA sequence differentiation ability. Fast fabrication of a DNA sensor was also achieved by cutting and attaching the MWCNT-PDMS composite electrodes at an analyte solution-containable region. Our results pave the way for developing user-fabricated easily attached DNA sensors at low costs.

  16. Effects of Electrode Surface Morphology on the Transduction of Ionic Polymer-Metal Composites

    NASA Astrophysics Data System (ADS)

    Palmre, Viljar

    Ionic polymer-metal composites (IPMCs) are innovative smart materials that exhibit electromechanical and mechanoelectrical transduction (conversion of electrical input into mechanical deformation and vice versa). Due to low driving voltage (< 5 V) and ability to operate in aqueous environment, IPMCs are attractive for developing soft actuators and sensors for underwater robots and medical devices. This dissertation focuses on investigating the effects of electrode surface morphology in the transduction of Pt and Pd-Pt electrodes-based IPMCs, with the aim to improve the electrode surface design and thereby enhance the transduction performance of the material. Firstly, the synthesis techniques are developed to control and manipulate the surface structure of the mentioned electrodes through the electroless plating process. Using these techniques, IPMCs with different electrode surface structures are fabricated. The changes in the electrode surface morphology and the resulting effects on the material's electromechanical, mechanoelectrical, electrochemical and mechanical properties area examined and analyzed. This study shows that increasing the impregnation-reduction cycles under appropriate conditions leads to the formation and growth of platinum nanoparticles with sharp tips and edges---called Pt nanothorn assemblies---at the polymer-electrode interface. IPMCs designed with such nanostructured Pt electrodes are first to be reported. The experiments demonstrate that the formation and growth of Pt nanothorn assemblies at the electrode interface increases considerably the total transported charge during the transduction, thereby increasing significantly the displacement and blocking force output of IPMC. The improvement of the mentioned electromechanical properties was 3--5 times, depending on the input voltage and frequency used. Also, the peak mechanoelectrically induced voltage increased somewhat, although the overall effect of the surface structure was relatively

  17. Composite electrodes of activated carbon derived from cassava peel and carbon nanotubes for supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Taer, E.; Iwantono, Yulita, M.; Taslim, R.; Subagio, A.; Salomo, Deraman, M.

    2013-09-01

    In this paper, a composite electrode was prepared from a mixture of activated carbon derived from precarbonization of cassava peel (CP) and carbon nanotubes (CNTs). The activated carbon was produced by pyrolysis process using ZnCl2 as an activation agent. A N2 adsorption-desorption analysis for the sample indicated that the BET surface area of the activated carbon was 1336 m2 g-1. Difference percentage of CNTs of 0, 5, 10, 15 and 20% with 5% of PVDF binder were added into CP based activated carbon in order to fabricate the composite electrodes. The morphology and structure of the composite electrodes were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The SEM image observed that the distribution of CNTs was homogeneous between carbon particles and the XRD pattern shown the amorphous structure of the sample. The electrodes were fabricated for supercapacitor cells with 316L stainless steel as current collector and 1 M sulfuric acid as electrolyte. An electrochemical characterization was performed by using an electrochemical impedance spectroscopy (EIS) method using a Solatron 1286 instrument and the addition of CNTs revealed to improve the resistant and capacitive properties of supercapacitor cell.

  18. Electrodeposition of Gold on Lignocelluloses and Graphite-Based Composite Paper Electrodes for Superior Electrical Properties

    NASA Astrophysics Data System (ADS)

    Sultana, Ishrat; Razaq, Aamir; Idrees, M.; Asif, M. H.; Ali, Hassan; Arshad, Asim; Iqbal, Shahid; Ramay, Shahid M.; Hussain, Shahzada Qamar

    2016-10-01

    Graphite-based composites are commonly used as an anode and current collector for energy storage devices; however, they have inherently limited potential for large scale rechargeable systems due to a brittle structure. In this study, flexible and light-weight graphite-based electrodes are prepared by incorporation of lignocelluloses fibers directly collected from a self-growing plant, Typha Angistifolia. Electrical properties of graphite and lignocelluloses composite sheets are enhanced by electrodeposition of gold in a three-electrode setup. Electrochemical deposition of gold on a lignocelluloses/graphite paper electrode was obtained in potentiostatic mode by the application of reduction potential -0.95 V for 2000 s, 600 s, and 100 s. The gold-deposited paper electrodes showed efficient kinetics by shifting redox peaks towards lower potentials in cyclic voltammetry measurements, whereas impedance measurements revealed seven orders of magnitude reduction in the resistive properties. Incorporated flexibility and superior electrical/electrochemical performance within presented graphite-based composites will provide cutting-edge characteristics for high-tech application of energy storage devices by keeping a focus on modern disposable technology.

  19. Compliant Electrode and Composite Material for Piezoelectric Wind and Mechanical Energy Conversions

    NASA Technical Reports Server (NTRS)

    Chen, Bin (Inventor)

    2015-01-01

    A thin film device for harvesting energy from wind. The thin film device includes one or more layers of a compliant piezoelectric material formed from a composite of a polymer and an inorganic material, such as a ceramic. Electrodes are disposed on a first side and a second side of the piezoelectric material. The electrodes are formed from a compliant material, such as carbon nanotubes or graphene. The thin film device exhibits improved resistance to structural fatigue upon application of large strains and repeated cyclic loadings.

  20. Photoelectrochemical Properties of CuS-GeO2-TiO2 Composite Coating Electrode

    PubMed Central

    Wen, Xinyu; Zhang, Huawei

    2016-01-01

    The ITO (indium tin oxide) conductive glass-matrix CuS-GeO2-TiO2 composite coating was generated via EPD (electrophoretic deposition) and followed by a sintering treatment at 450°C for 40 minutes. Characterizations of the CuS-GeO2-TiO2 composite coating were taken by SEM (scanning electron microscope), XRD (X-ray diffraction), EDX (energy dispersive X-ray), UV-Vis DRS (ultraviolet-visible diffuse reflection spectrum), and FT-IR (Fourier transform infrared spectroscopy). Results showed that CuS and GeO2 had dispersed in this CuS-GeO2-TiO2 composite coating (mass percentages for CuS and GeO2 were 1.23% and 2.79%, respectively). The electrochemical studies (cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel polarization) of this CuS-GeO2-TiO2 composite coating electrode were performed in pH = 9.51 Na2CO3-NaHCO3 buffer solution containing 0.50 mol/L CH3OH under the conditions of visible light, ultraviolet light (λ = 365 nm), and dark (without light irradiation as control), respectively. Electrochemical studies indicated that this CuS-GeO2-TiO2 composite coating electrode had better photoelectrocatalytic activity than the pure TiO2 electrode in the electrocatalysis of methanol under visible light. PMID:27055277

  1. PEDOT-based composites as electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhao, Zhiheng; Richardson, Georgia F.; Meng, Qingshi; Zhu, Shenmin; Kuan, Hsu-Chiang; Ma, Jun

    2016-01-01

    Poly (3, 4-ethylenedioxythiophene) (denoted PEDOT) already has a brief history of being used as an active material in supercapacitors. It has many advantages such as low-cost, flexibility, and good electrical conductivity and pseudocapacitance. However, the major drawback is low stability, which means an obvious capacitance drop after a certain number of charge-discharge cycles. Another disadvantage is its limited capacitance and this becomes an issue for industrial applications. To solve these problems, there are several approaches including the addition of conducting nanofillers to increase conductivity, and mixing or depositing metal oxide to enhance capacitance. Furthermore, expanding the surface area of PEDOT is one of the main methods to improve its performance in energy storage applications through special processes; for example using a three-dimensional substrate or preparing PEDOT aerogel through freeze drying. This paper reviews recent techniques and outcomes of PEDOT based composites for supercapacitors, as well as detailed calculations about capacitances. Finally, this paper outlines the new direction and recent challenges of PEDOT based composites for supercapacitor applications.

  2. Performance of polyacrylonitrile-carbon nanotubes composite on carbon cloth as electrode material for microbial fuel cells.

    PubMed

    Kim, Sun-Il; Lee, Jae-Wook; Roh, Sung-Hee

    2011-02-01

    The performance of carbon nanotubes composite-modified carbon cloth electrodes in two-chambered microbial fuel cell (MFC) was investigated. The electrode modified with polyacrylonitrile-carbon nanotubes (PAN-CNTs) composite showed better electrochemical performance than that of plain carbon cloth. The MFC with the composite-modified anode containing 5 mg/cm2 PAN-CNTs exhibited a maximum power density of 480 mW/m2.

  3. Nickel foam-based manganese dioxide-carbon nanotube composite electrodes for electrochemical supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Jun; Yang, Quan Min; Zhitomirsky, Igor

    Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 2-4 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of slurries of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNTs) into porous nickel foam current collectors. In the composite electrodes, MWCNT formed a secondary conductivity network within the nickel foam cells. Obtained composite electrodes, containing 0-20 wt.% MWCNT with total mass loading of 40 mg cm -2, showed a capacitive behavior in the 0.1-0.5 M Na 2SO 4 solutions. The highest specific capacitance (SC) of 155 F g -1 was obtained at a scan rate of 2 mV s -1 in the 0.5 M Na 2SO 4 solutions. The SC increased with increasing MWCNT content in the composite materials and increasing Na 2SO 4 concentration in the solutions and decreased with increasing scan rate.

  4. Smooth ZnO:Al-AgNWs Composite Electrode for Flexible Organic Light-Emitting Device

    NASA Astrophysics Data System (ADS)

    Wang, Hu; Li, Kun; Tao, Ye; Li, Jun; Li, Ye; Gao, Lan-Lan; Jin, Guang-Yong; Duan, Yu

    2017-01-01

    The high interest in organic light-emitting device (OLED) technology is largely due to their flexibility. Up to now, indium tin oxide (ITO) films have been widely used as transparent conductive electrodes (TCE) in organic opto-electronic devices. However, ITO films, typically deposited on glass are brittle and they make it difficult to produce flexible devices, restricting their use for flexible devices. In this study, we report on a nano-composite TCE, which is made of a silver nanowire (AgNW) network, combined with aluminum-doped zinc oxide (ZnO:Al, AZO) by atomic layer deposition. The AgNWs/AZO composite electrode on photopolymer substrate shows a low sheet resistance of only 8.6 Ω/sq and a high optical transmittance of about 83% at 550 nm. These values are even comparable to conventional ITO on glass. In addition, the electrodes also have a very smooth surface (0.31 nm root-mean-square roughness), which is flat enough to contact the OLED stack. Flexible OLED were built with AgNWs/AZO electrodes, which suggests that this approach can replace conventional ITO TCEs in organic electronic devices in the future.

  5. Three dimensional studies of particle failure in silicon based composite electrodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Gonzalez, Joseph; Sun, Ke; Huang, Meng; Lambros, John; Dillon, Shen; Chasiotis, Ioannis

    2014-12-01

    Silicon based composite electrodes for lithium ion batteries are of significant interest because of their potential to be high capacity alternatives to the commonly used graphitic carbon anodes. A drawback to their use, however, is the Si particle debonding and fracture that occurs as a result of the volumetric expansion by the lithium host particles upon lithiation of the anode electrode. We use X-ray micro computed tomography to visualize the evolution of the internal microstructure of a silicon-based electrode before and after four lithiation steps during the first half cycle of the cell. We develop a novel threshold edge detect method to perform 3D volumetric measurements of silicon particle expansion. According to our results, 100% lithiation of the composite anode resulted in up to 290% volume expansion of individual Si particles. Furthermore, the global and localized image intensity histogram profiles from 3D data were used to analyze the silicon particle X-ray attenuation effects as a function of lithiation: a decreasing attenuation with lithiation and the propagation of the reaction front through a core-shell process between the original state and 25% lithiation of the silicon-based electrode have been observed.

  6. Mesoporous metal oxide microsphere electrode compositions and their methods of making

    DOEpatents

    Parans Paranthaman, Mariappan; Bi, Zhonghe; Bridges, Craig A; Brown, Gilbert M

    2014-12-16

    Compositions and methods of making are provided for treated mesoporous metal oxide microspheres electrodes. The compositions comprise (a) microspheres with an average diameter between 200 nanometers (nm) and 10 micrometers (.mu.m); (b) mesopores on the surface and interior of the microspheres, wherein the mesopores have an average diameter between 1 nm and 50 nm and the microspheres have a surface area between 50 m.sup.2/g and 500 m.sup.2/g, and wherein the composition has an electrical conductivity of at least 1.times.10.sup.-7 S/cm at 25.degree. C. and 60 MPa. The methods of making comprise forming a mesoporous metal oxide microsphere composition and treating the mesoporous metal oxide microspheres by at least one method selected from the group consisting of: (i) annealing in a reducing atmosphere, (ii) doping with an aliovalent element, and (iii) coating with a coating composition.

  7. Ultrathin Direct Atomic Layer Deposition on Composite Electrodes for Highly Durable and Safe Li-Ion Batteries

    DTIC Science & Technology

    2010-01-01

    initiates thermal runaway.[9] In most previous reports films of metal oxides and metal phosphates have been deposited on powder electrode materials with...method to apply conformal thin films on high-surface area tortuous networks using sequential, self-limiting surface reactions.[10] Also, the thickness...the pores of composite electrodes to deposit a conformal Al2O3 film in the torturous path of the entire electrode structure. As discussed in more

  8. Electrosorption of ions from aqueous solutions with carbon nanotubes and nanofibers composite film electrodes

    SciTech Connect

    Wang, X. Z.; Li, M. G.; Chen, Y. W.; Cheng, R. M.; Huang, S. M.; Pan, L. K.; Sun, Z.

    2006-07-31

    Electrosorption of ions from aqueous solutions with carbon nanotubes and nanofibers (CNTs-CNFs) composite film electrodes has been demonstrated. The large area CNTs-CNFs film was directly grown on Ni plate by low pressure and low temperature thermal chemical vapor deposition. The CNTs-CNFs electrodes have great advantages such as low cost, easy operation, long-term reproducibility, and integrity of monolithic CNTs-CNFs film and current collector. Batch-mode experiments at low voltage (0.4-2 V) were conducted in a continuously recycling system to investigate the electrosorption process. Purification of water with good reproducibility was achieved because of optimal pore size distribution of CNTs-CNFs composite films.

  9. Application of Desalination with CFRP Composite Electrode to Concrete Deteriorated by Chloride Attack

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Keisuke; Ueda, Takao; Nanasawa, Akira

    As a new rehabilitation technique for recovery both of loading ability and durability of concrete structures deteriorated by chloride attack, desalination (electrochemical chloride removal technique from concrete) using CFRP composite electrode bonding to concrete has been developed. In this study, basic application was tried using small RC specimens, and also application to the large-scale RC beams deteriorated by the chloride attack through the long-term exposure in the outdoors was investigated. As the result of bending test of treated specimens, the decrease of strengthening effect with the electrochemical treatment was observed in the case of small specimens using low absorption rate resin for bonding, on the other hand, in the case of large-scale RC beam using 20% absorption rate resin for bonding CFRP composite electrode, enough strengthening effect was obtained by the bending failure of RC beam with the fracture of CFRP board.

  10. Electrosorption of ions from aqueous solutions with carbon nanotubes and nanofibers composite film electrodes

    NASA Astrophysics Data System (ADS)

    Wang, X. Z.; Li, M. G.; Chen, Y. W.; Cheng, R. M.; Huang, S. M.; Pan, L. K.; Sun, Z.

    2006-07-01

    Electrosorption of ions from aqueous solutions with carbon nanotubes and nanofibers (CNTs-CNFs) composite film electrodes has been demonstrated. The large area CNTs-CNFs film was directly grown on Ni plate by low pressure and low temperature thermal chemical vapor deposition. The CNTs-CNFs electrodes have great advantages such as low cost, easy operation, long-term reproducibility, and integrity of monolithic CNTs-CNFs film and current collector. Batch-mode experiments at low voltage (0.4-2V) were conducted in a continuously recycling system to investigate the electrosorption process. Purification of water with good reproducibility was achieved because of optimal pore size distribution of CNTs-CNFs composite films.

  11. Low energy milling method, low crystallinity alloy, and negative electrode composition

    DOEpatents

    Le, Dihn B; Obrovac, Mark N; Kube, Robert Y; Landucci, James R

    2012-10-16

    A method of making nanostructured alloy particles includes milling a millbase in a pebble mill containing milling media. The millbase comprises: (i) silicon, and (ii) at least one of carbon or a transition metal, and wherein the nanostructured alloy particles are substantially free of crystalline domains greater than 50 nanometers in size. A method of making a negative electrode composition for a lithium ion battery including the nanostructured alloy particles is also disclosed.

  12. Pt-Free Counter Electrodes with Carbon Black and 3D Network Epoxy Polymer Composites

    NASA Astrophysics Data System (ADS)

    Kang, Gyeongho; Choi, Jongmin; Park, Taiho

    2016-03-01

    Carbon black (CB) and a 3D network epoxy polymer composite, representing dual functions for conductive corrosion protective layer (CCPL) and catalytic layer (CL) by the control of CB weight ratio against polymer is developed. Our strategy provides a proper approach which applies high catalytic ability and chemical stability of CB in corrosive triiodide/iodide (I3-/I-) redox electrolyte system. The CB and a 3D network epoxy polymer composite coated on the stainless steel (SS) electrode to alternate counter electrodes in dye sensitized solar cells (DSSCs). A two-step spray pyrolysis process is used to apply a solution containing epoxy monomers and a polyfunctional amine hardener with 6 wt% CB to a SS substrate, which forms a CCPL. Subsequently, an 86 wt% CB is applied to form a CL. The excellent catalytic properties and corrosion protective properties of the CB and 3D network epoxy polymer composites produce efficient counter electrodes that can replace fluorine-doped tin oxide (FTO) with CCPL/SS and Pt/FTO with CL/CCPL/SS in DSSCs. This approach provides a promising approach to the development of efficient, stable, and cheap solar cells, paving the way for large-scale commercialization.

  13. Pt-Free Counter Electrodes with Carbon Black and 3D Network Epoxy Polymer Composites

    PubMed Central

    Kang, Gyeongho; Choi, Jongmin; Park, Taiho

    2016-01-01

    Carbon black (CB) and a 3D network epoxy polymer composite, representing dual functions for conductive corrosion protective layer (CCPL) and catalytic layer (CL) by the control of CB weight ratio against polymer is developed. Our strategy provides a proper approach which applies high catalytic ability and chemical stability of CB in corrosive triiodide/iodide (I3−/I−) redox electrolyte system. The CB and a 3D network epoxy polymer composite coated on the stainless steel (SS) electrode to alternate counter electrodes in dye sensitized solar cells (DSSCs). A two-step spray pyrolysis process is used to apply a solution containing epoxy monomers and a polyfunctional amine hardener with 6 wt% CB to a SS substrate, which forms a CCPL. Subsequently, an 86 wt% CB is applied to form a CL. The excellent catalytic properties and corrosion protective properties of the CB and 3D network epoxy polymer composites produce efficient counter electrodes that can replace fluorine-doped tin oxide (FTO) with CCPL/SS and Pt/FTO with CL/CCPL/SS in DSSCs. This approach provides a promising approach to the development of efficient, stable, and cheap solar cells, paving the way for large-scale commercialization. PMID:26961256

  14. Coulometric differential FFT admittance voltammetry determination of Amlodipine in pharmaceutical formulation by nano-composite electrode.

    PubMed

    Norouzi, Parviz; Gupta, Vinod Kumar; Larijani, Bagher; Rasoolipour, Solmaz; Faridbod, Farnoush; Ganjali, Mohammad R

    2015-01-01

    An electrochemical detection technique based on combination of was coulometric differential fast Fourier transformation admittance voltammetry (CDFFTAV) and nano-composite film modified glassy carbon electrode was successfully applied for sensitive determination of Amlodipine. The nano-composite film was made by a mixture of ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4), multiwall carbon nanotube and Au nanoparticles as electrochemical mediators. Studies reveal that the irreversible oxidation of Amlodipine was highly facile on the electrode surface. The electrochemical response was established on calculation of the charge under the admittance peak, which was obtained by discrete integration of the admittance response in a selected potential range, obtained in a flow injection analysis. Once established the best operative optimum conditions, the resulting nano-composite film electrode showed a catalytic effect on the oxidation of the analyte. The response is linear in the Amlodipine concentration range of 1.0 × 10(-9) to 2.0 × 10(-7)M with a detection limit of 1.25 × 10(-10)M. Moreover, the proposed technique exhibited high sensitivity, fast response time (less than 6s) and long-term stability and reproducibility around 96%, and it was successfully used to the determination of Amlodipine content in the pharmaceutical formulation.

  15. rGO/SWCNT composites as novel electrode materials for electrochemical biosensing.

    PubMed

    Huang, Tzu-Yen; Huang, Jen-Hsien; Wei, Hung-Yu; Ho, Kuo-Chuan; Chu, Chih-Wei

    2013-05-15

    In this study we performed electrochemical sensing using conductive carbon composite films containing reduced graphene oxide (rGO) and single-walled carbon nanotubes (SWCNTs) as electrode modifiers on glassy carbon electrodes (GCEs). Raman spectroscopy, transmission electron microscopy, atomic force microscopy, and scanning electron microscopy all suggested that the rGO acted as a surfactant, covering and smoothing out the surface, and that the SWCNTs acted as a conducting bridge to connect the isolated rGO sheets, thereby (i) minimizing the barrier for charge transfer between the rGO sheets and (ii) increasing the conductivity of the film. We used the rGO/SWCNT-modified GCE as a sensor to analyze hydrogen peroxide (H2O2) and β-nicotinamide adenine dinucleotide (NADH), obtaining substantial improvements in electrochemical reactivity and detection limits relative to those obtained from rGO- and SWCNT-modified electrodes, presumably because of the higher conductivity and greater coverage on the GCE, due to π-π interactions originating from the graphitic structures of the rGO and SWCNTs. The electrocatalysis response was measured by cyclic voltammetry and amperometric current-time (i-t) curve techniques. The linear concentration range of H2O2 and NADH detection at rGO/SWCNT-modified electrode is 0.5-5M and 20-400μM. The sensitivity for H2O2 and NADH detection is 2732.4 and 204μAmM(-1)cm(-2), and the limit of detection is 1.3 and 0.078μM respectively. Furthermore, interference tests indicated that the carbon composite film exhibited high selectivity toward H2O2 and NADH. Using GO as a solubilizing agent for SWCNTs establishes a new class of carbon electrodes for electrochemical sensors.

  16. Intrinsically stretchable transparent electrodes based on silver-nanowire-crosslinked-polyacrylate composites.

    PubMed

    Hu, Weili; Niu, Xiaofan; Li, Lu; Yun, Sungryul; Yu, Zhibin; Pei, Qibing

    2012-08-31

    Stretchable transparent composites have been synthesized consisting of a silver nanowire (AgNW) network embedded in the surface layer of a crosslinked poly(acrylate) matrix. The interpenetrating networks of AgNWs and the crosslinked polymer matrix lead to high surface conductivity, high transparency, and rubbery elasticity. The presence of carboxylic acid groups on the polymer chains enhances the bonding between AgNWs and the polymer matrix, and further increases the stretchability of the composites. The sheet resistance of the composite electrode increases by only 2.3 times at 50% strain. Repeated stretching to 50% strain and relaxation only causes a small increase of the sheet resistance after 600 cycles. The morphology of the composites during reversible stretching and relaxation has been investigated to expound the conductivity changes.

  17. Intrinsically stretchable transparent electrodes based on silver-nanowire-crosslinked-polyacrylate composites

    NASA Astrophysics Data System (ADS)

    Hu, Weili; Niu, Xiaofan; Li, Lu; Yun, Sungryul; Yu, Zhibin; Pei, Qibing

    2012-08-01

    Stretchable transparent composites have been synthesized consisting of a silver nanowire (AgNW) network embedded in the surface layer of a crosslinked poly(acrylate) matrix. The interpenetrating networks of AgNWs and the crosslinked polymer matrix lead to high surface conductivity, high transparency, and rubbery elasticity. The presence of carboxylic acid groups on the polymer chains enhances the bonding between AgNWs and the polymer matrix, and further increases the stretchability of the composites. The sheet resistance of the composite electrode increases by only 2.3 times at 50% strain. Repeated stretching to 50% strain and relaxation only causes a small increase of the sheet resistance after 600 cycles. The morphology of the composites during reversible stretching and relaxation has been investigated to expound the conductivity changes.

  18. Mesoporous metal oxide microsphere electrode compositions and their methods of making

    SciTech Connect

    Paranthaman, Mariappan Parans; Liu, Hansan; Brown, Gilbert M.; Sun, Xiao-Guang; Bi, Zhonghe

    2016-12-06

    Compositions and methods of making are provided for mesoporous metal oxide microspheres electrodes. The mesoporous metal oxide microsphere compositions comprise (a) microspheres with an average diameter between 200 nanometers (nm) and 10 micrometers (.mu.m); (b) mesopores on the surface and interior of the microspheres, wherein the mesopores have an average diameter between 1 nm and 50 nm and the microspheres have a surface area between 50 m.sup.2/g and 500 m.sup.2/g. The methods of making comprise forming composite powders. The methods may also comprise refluxing the composite powders in a basic solution to form an etched powder, washing the etched powder with an acid to form a hydrated metal oxide, and heat-treating the hydrated metal oxide to form mesoporous metal oxide microspheres.

  19. Working from Both Sides: Composite Metallic Semitransparent Top Electrode for High Performance Perovskite Solar Cells.

    PubMed

    Dai, Xuezeng; Zhang, Ye; Shen, Heping; Luo, Qiang; Zhao, Xingyue; Li, Jianbao; Lin, Hong

    2016-02-01

    We report herein perovskite solar cells using solution-processed silver nanowires (AgNWs) as transparent top electrode with markedly enhanced device performance, as well as stability by evaporating an ultrathin transparent Au (UTA) layer beneath the spin-coated AgNWs forming a composite transparent metallic electrode. The interlayer serves as a physical separation sandwiched in between the perovskite/hole transporting material (HTM) active layer and the halide-reactive AgNWs top-electrode to prevent undesired electrode degradation and simultaneously functions to significantly promote ohmic contact. The as-fabricated semitransparent PSCs feature a Voc of 0.96 V, a Jsc of 20.47 mA cm(-2), with an overall PCE of over 11% when measured with front illumination and a Voc of 0.92 V, a Jsc of 14.29 mA cm(-2), and an overall PCE of 7.53% with back illumination, corresponding to approximately 70% of the value under normal illumination conditions. The devices also demonstrate exceptional fabrication repeatability and air stability.

  20. Grid indentation analysis of mechanical properties of composite electrodes in Li-ion batteries

    SciTech Connect

    Vasconcelos, Luize Scalco de; Xu, Rong; Li, Jianlin; Zhao, Kejie

    2016-03-09

    We report that electrodes in commercial rechargeable batteries are microscopically heterogeneous materials. The constituent components, including active materials, polymeric binders, and porous conductive matrix, often have large variation in their mechanical properties, making the mechanical characterization of composite electrodes a challenging task. In a model system of LiNi0.5Mn0.3Co0.2O2 cathode, we employ the instrumented grid indentation to determine the elastic modulus and hardness of the constituent phases. The approach relies on a large array of nanoindentation experiments and statistical analysis of the resulting data provided that the maximum indentation depth is carefully chosen. The statistically extracted properties of the active particles and the surrounding medium are in good agreement with the tests of targeted indentation at selected sites. Lastly, the combinatory technique of grid indentation and statistical deconvolution represents a fast and reliable route to quantify the mechanical properties of composite electrodes that feed the parametric input for the mechanics models.

  1. Grid indentation analysis of mechanical properties of composite electrodes in Li-ion batteries

    DOE PAGES

    Vasconcelos, Luize Scalco de; Xu, Rong; Li, Jianlin; ...

    2016-03-09

    We report that electrodes in commercial rechargeable batteries are microscopically heterogeneous materials. The constituent components, including active materials, polymeric binders, and porous conductive matrix, often have large variation in their mechanical properties, making the mechanical characterization of composite electrodes a challenging task. In a model system of LiNi0.5Mn0.3Co0.2O2 cathode, we employ the instrumented grid indentation to determine the elastic modulus and hardness of the constituent phases. The approach relies on a large array of nanoindentation experiments and statistical analysis of the resulting data provided that the maximum indentation depth is carefully chosen. The statistically extracted properties of the active particlesmore » and the surrounding medium are in good agreement with the tests of targeted indentation at selected sites. Lastly, the combinatory technique of grid indentation and statistical deconvolution represents a fast and reliable route to quantify the mechanical properties of composite electrodes that feed the parametric input for the mechanics models.« less

  2. PEDOT:PSS as multi-functional composite material for enhanced Li-air-battery air electrodes

    PubMed Central

    Yoon, Dae Ho; Yoon, Seon Hye; Ryu, Kwang-Sun; Park, Yong Joon

    2016-01-01

    We propose PEDOT:PSS as a multi-functional composite material for an enhanced Li-air-battery air electrode. The PEDOT:PSS layer was coated on the surface of carbon (graphene) using simple method. A electrode containing PEDOT:PSS-coated graphene (PEDOT electrode) could be prepared without binder (such as PVDF) because of high adhesion of PEDOT:PSS. PEDOT electrode presented considerable discharge and charge capacity at all current densities. These results shows that PEDOT:PSS acts as a redox reaction matrix and conducting binder in the air electrode. Moreover, after cycling, the accumulation of reaction products due to side reaction in the electrode was significantly reduced through the use of PEDOT:PSS. This implies that PEDOT:PSS coating layer can suppress the undesirable side reactions between the carbon and electrolyte (and/or Li2O2), which causes enhanced Li-air cell cyclic performance. PMID:26813852

  3. Method of making composition suitable for use as inert electrode having good electrical conductivity and mechanical properties

    DOEpatents

    Ray, Siba P.; Rapp, Robert A.

    1986-01-01

    An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily.

  4. Method of making composition suitable for use as inert electrode having good electrical conductivity and mechanical properties

    DOEpatents

    Ray, S.P.; Rapp, R.A.

    1986-04-22

    An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily. 8 figs.

  5. Amorphous Vanadium Oxide/Carbon Composite Positive Electrode for Rechargeable Aluminum Battery.

    PubMed

    Chiku, Masanobu; Takeda, Hiroki; Matsumura, Shota; Higuchi, Eiji; Inoue, Hiroshi

    2015-11-11

    Amorphous vanadium oxide/carbon composite (V2O5/C) was first applied to the positive electrode active material for rechargeable aluminum batteries. Electrochemical properties of V2O5/C were investigated by cyclic voltammetry and charge-discharge tests. Reversible reduction/oxidation peaks were observed for the V2O5/C electrode and the rechargeable aluminum cell showed the maximum discharge capacity over 200 mAh g(-1) in the first discharging. The XPS analyses after discharging and the following charging exhibited that the redox of vanadium ion in the V2O5/C active material occurred during discharging and charging, and the average valence of V changed between 4.14 and 4.85.

  6. Carbon Microfibers Grown on Graphite Electrode During Fullerene Generation Using Composite Graphite Rods

    NASA Astrophysics Data System (ADS)

    Ata, Masafumi; Kijima, Yasunori; Imoto, Hiroshi; Matsuzawa, Nobuyuki; Takahashi, Noboru

    1994-07-01

    Using carbon/metal composite electrodes, silver-colored carbon deposits were obtained on the top edges of negative electrodes during electric arc vaporization for fullerene generation. Needle-shaped, rod-shaped, and winding carbon fibers 20 30 µm in length and 3 4 µm in diameter were observed on the surface of the deposits, using a scanning electron microscope (SEM). The results of energy-dispersive X-ray (EDX) microanalysis on the fibers showed that metal carbides exist at the top portions of these fibers. It was suggested that the growth of such fibers was induced by the catalytic activity of small clusters of metal carbides which act as seeds. The structures of the fibers were discussed based on these experimental results.

  7. Electrodes patterning on ionic polymer metal composite for making smooth surface on tunable mirrors

    NASA Astrophysics Data System (ADS)

    Cheng, Wei; Su, Guo-Dung J.

    2012-10-01

    Deformable mirror is a very important reflective component in optical system, which can vary the focal length while the surface deform. Nowadays several type of material were used as deformable mirror, such as liquid lens and MEMS deformable mirror. MEMS deformable mirror have been developed in our group and shows the potential. However, the problem of high actuation voltage is not easy to solve. In this thesis, we proposed using low voltage applied material, which is called Ioic-Polymer Metal Composite (IPMC) with the advantage of low applied voltage but high actuation performance. Arbitrary-shaped electrode IPMC was successfully fabricated by simply covering a shadow mask during electroless plating. Maximum central displacement of ellipsoid-shaped electrode IPMC can be achieved up to 350 μm under 2.5 volts applied. We believe this technique can be used in optical system as a deformable mirror in the future.

  8. Selective removal of nitrate ion using a novel composite carbon electrode in capacitive deionization.

    PubMed

    Kim, Yu-Jin; Choi, Jae-Hwan

    2012-11-15

    We fabricated nitrate-selective composite carbon electrodes (NSCCEs) for use in capacitive deionization to remove nitrate ions selectively from a solution containing a mixture of anions. The NSCCE was fabricated by coating the surface of a carbon electrode with the anion exchange resin, BHP55, after grinding the resin into fine powder. BHP55 is known to be selective for nitrate ions. We performed desalination experiments on a solution containing 5.0 mM NaCl and 2.0 mM NaNO(3) using the NSCCE system constructed with the fabricated electrode. The selective removal of nitrate in the NSCCE system was compared to a membrane capacitive deionization (MCDI) system constructed with ion exchange membranes and carbon electrodes. The total quantity of chloride and nitrate ions adsorbed onto the unit area of the electrode in the MCDI system was 25 mmol/m(2) at a cell potential of 1.0 V. The adsorption of nitrate ions was 8.3 mmol/m(2), accounting for 33% of the total. In contrast, the total anion adsorption in the NSCCE system was 34 mmol/m(2), 36% greater than the total anion adsorption of the MCDI system. The adsorption of nitrate ions was 19 mmol/m(2), 2.3-times greater than the adsorption in the MCDI system. These results showed that the ions were initially adsorbed by an electrostatic force, and the ion exchange reactions then occurred between the resin powder in the coated layer and the solution containing mixed anions.

  9. Heterogeneous Configuration of a Ag Nanowire/Polymer Composite Structure for Selectively Stretchable Transparent Electrodes.

    PubMed

    Kim, Youngmin; Jun, Sungwoo; Ju, Byeong-Kwon; Kim, Jong-Woong

    2017-03-01

    One of the most important aspects that we need to consider in the design of intrinsically stretchable electrodes is that most electronic devices that can be formed on them are not stretchable themselves. This discrepancy can induce severe stress singularities at the interfaces between stiff devices and stretchable electrodes, leading to catastrophic device delamination when the substrate is stretched. Here, we suggest a novel solution to this challenge which involves introducing a photolithography-based rigid-island approach to fabricate the heterogeneous configuration of a silver nanowire (AgNW)/polymer composite structure. For this, we designed two new transparent polymers: a photopatternable polymer that is rigid yet flexible, and a stretchable polymer, both of which have identical acrylate functional groups. Patterning of the rigid polymer and subsequent overcoating of the soft polymer formed rigid island disks embedded in the soft polymer, resulting in a selectively stretchable transparent film. Strong covalent bonds instead of weak physical interactions between the polymers strengthened the cohesive force at the interface of the rigid/soft polymers. Inverted-layer processing with a percolated AgNW network was used to form a heterogeneous AgNW/polymer composite structure that can be used as a selectively stretchable transparent electrode. An optimized structural configuration prevented the resistance of the rigid electrode from varying up to a lateral strain of 70%. A repeated stretch/release test with 60% strain for 5000 cycles did not cause any severe damage to the structure, revealing that the fabricated structure was mechanically stable and reliable.

  10. Nickel-cadmium batteries: effect of electrode phase composition on acid leaching process.

    PubMed

    Nogueira, C A; Margarido, F

    2012-01-01

    At the end of their life, Ni-Cd batteries cause a number of environmental problems because of the heavy metals they contain. Because of this, recycling of Ni-Cd batteries has been carried out by dedicated companies using, normally, pyrometallurgical technologies. As an alternative, hydrometallurgical processes have been developed based on leaching operations using several types of leachants. The effect of factors like temperature, acid concentration, reaction time, stirring speed and grinding of material on the leaching yields of metals contained in anodic and cathodic materials (nickel, cadmium and cobalt) using sulphuric acid, is herein explained based on the structural composition of the electrode materials. The nickel, cobalt and cadmium hydroxide phases, even with a small reaction time (less than 15 minutes) and low temperature (50 degrees C) and acid concentration (1.1 M H2SO4), were efficiently leached. However, leaching of the nickel metallic phase was more difficult, requiring higher values of temperature, acid concentration and reaction time (e.g. 85 degrees C, 1.1 M H2SO4 and 5 h, respectively) in order to obtain a good leaching efficiency for anodic and cathodic materials (70% and 93% respectively). The stirring speed was not significant, whereas the grinding of electrode materials seems to promote the compaction of particles, which appears to be critical in the leaching of Ni degrees. These results allowed the identification and understanding of the relationship between the structural composition of electrode materials and the most important factors that affect the H2SO4 leaching of spent Ni-Cd battery electrodes, in order to obtain better metal-recovery efficiency.

  11. Ultra-thin-polysiloxane-film-composite membranes for the optimisation of amperometric oxidase enzyme electrodes.

    PubMed

    Myler, S; Collyer, S D; Bridge, K A; Higson, S P J

    2002-01-01

    An outer ultra-thin-polydimethyldichlorosiloxane film composite membrane has been used as the outer covering barrier in an amperometric glucose oxidase enzyme electrode biosensor. The composite membrane was formed via the condensation polymerisation of dimethyldichlorosilane at the surface of a host porous alumina membrane. Homogeneous polydimethyldichlorosiloxane films of <100 nm thickness acted as effective substrate diffusional barriers and were supported by the underlying porous alumina surface. Glucose and oxygen permeability coefficients were determined using diffusion chamber apparatus. Polysiloxane composite membranes were found to offer some screening functionality towards anionic biological interferents such as ascorbate. On exposure to blood an approximate 25% signal drift was observed during the first 2 h exposure to blood; after this time responses remained almost stable. Whole blood glucose determinations showed a close correlation (r(2)=0.98) to analyses performed via standard hospital analyses.

  12. Graphene/polyaniline composite sponge of three-dimensional porous network structure as supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Jiu-Xing, Jiang; Xu-Zhi, Zhang; Zhen-Hua, Wang; Jian-Jun, Xu

    2016-04-01

    As a supercapacitor electrode, the graphene/polyaniline (PANI) composite sponge with a three-dimensional (3D) porous network structure is synthesized by a simple three-step method. The three steps include an in situ polymerization, freeze-drying and reduction by hydrazine vapor. The prepared sponge has a large specific surface area and porous network structure, so it is in favor of spreading the electrolyte ion and increasing the charge transfer efficiency of the system. The process of preparation is simple, easy to operate and low cost. The composite sponge shows better electrochemical performance than the pure individual graphene sponge while PANI cannot keep the shape of a sponge. Such a composite sponge exhibits specific capacitances of 487 F·g-1 at 2 mV/s compared to pristine PANI of 397 F·g-1. Project supported by the Natural Science Foundation from Harbin University of Science and Technology and Harbin Institute of Technology.

  13. LiNi0.5Mn1.5O4-based composite electrodes with improved properties prepared by a slurry spray deposition process

    NASA Astrophysics Data System (ADS)

    Yu, Ran; Sun, Yi; Zou, Bang-Kun; Deng, Miao-Miao; Xie, Jing-Ying; Chen, Chun-Hua

    2017-02-01

    A slurry spray deposition (SSD) process is utilized to prepare a LiNi0.5Mn1.5O4-based composite electrode supported on an aluminum foil. The spray deposition process is performed at room temperature through the atomization and deposition of the composite electrode slurry. A comparative LiNi0.5Mn1.5O4-based composite electrode is also prepared by the traditional blade coating method. The surface morphology and elements mapping of the electrodes are measured by scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The adhesion between the composite electrode layers and the aluminum foil is also tested. A parallel evaluation on the mechanical and electrochemical performances of the two kinds of electrodes is conducted. The SSD electrode exhibits improved adhesion, cycling stability and rate capability. Therefore, the SSD process is an effective way to fabricate advanced electrodes for high performance lithium ion cells.

  14. Cerium-modified doped strontium titanate compositions for solid oxide fuel cell anodes and electrodes for other electrochemical devices

    DOEpatents

    Marina, Olga A [Richland, WA; Stevenson, Jeffry W [Richland, WA

    2010-11-23

    The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells and electrochemical devices such as solid oxide fuel cells, electrolyzers, sensors, pumps and the like, the compositions comprising cerium-modified doped strontium titanate. The invention also provides novel methods for making and using anode material compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having anodes comprising the compositions.

  15. Cerium-modified doped strontium titanate compositions for solid oxide fuel cell anodes and electrodes for other electrochemical devices

    DOEpatents

    Marina, Olga A [Richland, WA; Stevenson, Jeffry W [Richland, WA

    2010-03-02

    The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells and electrochemical devices such as solid oxide fuel cells, electrolyzers, sensors, pumps and the like, the compositions comprising cerium-modified doped strontium titanate. The invention also provides novel methods for making and using anode material compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having anodes comprising the compositions.

  16. Time-dependent deformation behavior of polyvinylidene fluoride binder: Implications on the mechanics of composite electrodes

    NASA Astrophysics Data System (ADS)

    Santimetaneedol, Arnuparp; Tripuraneni, Rajasekhar; Chester, Shawn A.; Nadimpalli, Siva P. V.

    2016-11-01

    The majority of existing battery models that simulate composite electrode behavior assume the binder as a linear elastic material due to lack of a thorough understanding of time-dependent mechanical behavior of binders. Here, thin films of polyvinylidene fluoride binder, prepared according to commercial battery manufacturing method, are subjected to standard monotonic, load-unload, and relaxation tests to characterize the time-dependent mechanical behavior. The strain in the binder samples is measured with the digital image correlation technique to eliminate experimental errors. The experimental data showed that for (charging/discharging) time scales of practical importance, polyvinylidene fluoride behaves more like an elastic-viscoplastic material as opposed to a visco-elastic material; based on this observation, a simple elastic-viscoplastic model, calibrated against the data is adopted to represent the deformation behavior of binder in a Si-based composite electrode; the lithiation/delithiation process of this composite was simulated at different C rates and the stress/strain behavior was monitored. It is observed that the linear elastic assumption of the binder leads to inaccurate results and the time-dependent constitutive behavior of the binder not only leads to accurate prediction of the mechanics but is an essential step towards developing advanced multi-physics models for simulating the degradation behavior of batteries.

  17. Electrochemical capacitor performance of hydrous ruthenium oxide/mesoporous carbon composite electrodes

    NASA Astrophysics Data System (ADS)

    Jang, Jong H.; Han, Sangjin; Hyeon, Taeghwan; Oh, Seung M.

    Ruthenium/carbon composite materials are prepared by impregnating ruthenium(III) acetylacetonate into a mesoporous carbon (average pore diameter=12 mn, pore volume=3.6 cm 3 g -1) and then heat treatment at 320 °C for 2 h under an argon atmosphere. The metallic ruthenium nanoparticles are converted to pseudo-capacitive hydrous ruthenium oxide by electrochemical oxidation at 0.75 V (versus SCE) for 2 h in 2.0 M H 2SO 4. The specific capacitance of the composite electrodes, which is the sum of the double-layer capacitance of mesoporous carbon and the pseudo-capacitance of hydrous ruthenium oxide, reaches 243 F g -1 with heavy loading. As the loading is increased, however, the degree of ruthenium utilization for a pseudo-capacitor becomes poorer, presumably due to a limited conversion to the hydrous oxide form. The rate capability of composite electrodes also decreases with increase in ruthenium loading, due to an increase in both the equivalent series resistance (ESR) and the overall capacitance value. The ESR enlargement is caused mainly an increase in the electrolyte resistance within pores which, in turn, results from a pore narrowing with ruthenium loading Hindered ionic motion in narrowed pores can explain this feature. An increase in the RC time constant with ruthenium loading is further verified by ac impedance measurements.

  18. Magnetohydrodynamic electrode

    DOEpatents

    Boquist, Carl W.; Marchant, David D.

    1978-01-01

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

  19. Electrode Build-Up of Reducible Metal Composites toward Achievable Electrochemical Conversion of Carbon Dioxide.

    PubMed

    Lee, Seunghwa; Lee, Jaeyoung

    2016-02-19

    At the beginning of the 21st century, our world is faced with a global-warming problem due to the continuous increase in carbon dioxide emission, and thus, the development of novel experimental techniques is needed. The electrochemical conversion of carbon dioxide into high-value organic compounds could be of vital importance to solve this issue. The biggest challenge has always been to develop an electrocatalyst that is chemically active and structurally stable. Herein, previous studies, recent approaches, and current points of view on the electrode structure of metal oxide composites for the advanced electrochemical conversion of carbon dioxide are reviewed.

  20. Manufacturing of industry-relevant silicon negative composite electrodes for lithium ion-cells

    NASA Astrophysics Data System (ADS)

    Nguyen, B. P. N.; Chazelle, S.; Cerbelaud, M.; Porcher, W.; Lestriez, B.

    2014-09-01

    In this paper, Poly (acrylic-co-maleic) acid (PAMA) is used as a dispersant to improve the stability of electrodes slurries for large scale processing of Silicon based negative composite electrode. The stability and homogeneity of the slurries are characterized using different techniques. Sedimentation test, electrical measurement, SEM-EDX observations as well as rheological measurements show that a more homogeneous distribution of carbon black (CB) inside the stack of Si particles is reached with presence of PAMA. However, the amount of PAMA is limited due to the competition in the adsorption of PAMA and Carboxylmethyl cellulose (CMC) at the surface of the CB particles. Upon cycling with capacity limitation, the optimized electrode formulation at lab scale could achieve more than 400 cycles with surface capacity ∼2.5-3.3 mAh cm-2. At the pilot scale, the improvement of adhesion of the tape to the current collector by using Styrene-co-Butadiene rubber copolymer latex (SB) helps to maintain long cycle life while calendaring is detrimental to electrochemical properties.

  1. Negatively strain-dependent electrical resistance of magnetically arranged nickel composites: application to highly stretchable electrodes and stretchable lighting devices.

    PubMed

    Kim, Sangwoo; Byun, Junghwan; Choi, Seongdae; Kim, Donghyun; Kim, Taehoon; Chung, Seungjun; Hong, Yongtaek

    2014-05-21

    A novel property of the negatively strain-dependent electrical resistance change of nickel conductive composites is presented. The composite shows negatively strain-dependent resistance change when magnetically arranged, while most conductive materials show opposite behavior. This negative dependency is utilized to produce highly stretchable electrodes and to demonstrate a new conceptual resolution-sustainable stretchable lighting/display device.

  2. Hierarchically ordered mesoporous carbon/graphene composites as supercapacitor electrode materials.

    PubMed

    Song, Yanjie; Li, Zhu; Guo, Kunkun; Shao, Ting

    2016-08-25

    Hierarchically ordered mesoporous carbon/graphene (OMC/G) composites have been fabricated by means of a solvent-evaporation-induced self-assembly (EISA) method. The structures of these composites are characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and nitrogen adsorption-desorption at 77 K. These results indicate that OMC/G composites possess the hierarchically ordered hexagonal p6mm mesostructure with the lattice unit parameter and pore diameter close to 10 nm and 3 nm, respectively. The specific surface area of OMC/G composites after KOH activation is high up to 2109.2 m(2) g(-1), which is significantly greater than OMC after activation (1474.6 m(2) g(-1)). Subsequently, the resulting OMC/G composites as supercapacitor electrode materials exhibit an outstanding capacitance as high as 329.5 F g(-1) in 6 M KOH electrolyte at a current density of 0.5 A g(-1), which is much higher than both OMC (234.2 F g(-1)) and a sample made by mechanical mixing of OMC with graphene (217.7 F g(-1)). In addition, the obtained OMC/G composites display good cyclic stability, and the final capacitance retention is approximately 96% after 5000 cycles. These ordered mesopores in the OMC/G composites are beneficial to the accessibility and rapid diffusion of the electrolyte, while graphene in OMC/G composites can also facilitate the transport of electrons during the processes of charging and discharging owing to its high conductivity, thereby leading to an excellent energy storage performance. The method demonstrated in this work would open up a new route to design and develop graphene-based architectures for supercapacitor applications.

  3. A reduced graphene oxide/Co3O4 composite for supercapacitor electrode

    SciTech Connect

    Xiang, Chengcheng; Li, Ming; Zhi, Mingjia; Manivannan, Ayyakkannu; Wu, Nianqiang

    2013-03-01

    20 nm sized Co3O4 nanoparticles are in-situ grown on the chemically reduced graphene oxide (rGO) sheets to form a rGO-Co3O4 composite during hydrothermal processing. The rGO-Co3O4 composite is employed as the pseudocapacitor electrode in the 2 M KOH aqueous electrolyte solution. The rGOCo3O4 composite electrode exhibits a specific capacitance of 472 F/g at a scan rate of 2 mV/s in a two-electrode cell. 82.6% of capacitance is retained when the scan rate increases to 100 mV/s. The rGOCo3O4 composite electrode shows high rate capability and excellent long-term stability. It also exhibits high energy density at relatively high power density. The energy density reaches 39.0 Wh/kg at a power density of 8.3 kW/kg. The super performance of the composite electrode is attributed to the synergistic effects of small size and good redox activity of the Co3O4 particles combined with high electronic conductivity of the rGO sheets.

  4. Glucose/ oxygen-based biofuel cell for biomedical applications: Electrode designs integrating carbon composite nanomaterials

    NASA Astrophysics Data System (ADS)

    Narvaez Villarrubia, Claudia Wuillma

    The relevance of this research is based on the need to develop biofuel cells as an alternative technology for powering implantable and/or extracorporeal medical devices. To accomplish this, processes occurring in nature are mimicked on the surface of bioelectrodes by enzymatic systems. In this research, various 'hot' topics, at different stages of the development of the technology, are revised in order to: accomplish understanding of the principles governing the normal operation of a glucose/O2 fuel cell, overcome obstacles to advance over the current technological limitations, and propose designs at the nanostructural catalytic layer scale as well as assembly platforms for practical cell operation. This research opens the possibilities to optimize electrode designs based on carbon composite nanomaterials, reagentless enzymatic systems and state-of-the-art enzymatic-stabilization procedures. The design and use of composite nanoarchitectural structures to achieve increased current density generation, cofactor and enzyme stability is a major accomplishment of this research. The technology herein can serve as a departing foundation to engineer electrode designs that meet the criteria required for reagentless biofuel cells for implantable and extracorporeal applications.

  5. Fe3O4/carbon coated silicon ternary hybrid composite as supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Oh, Ilgeun; Kim, Myeongjin; Kim, Jooheon

    2015-02-01

    In this study, Fe3O4/carbon-coated Si ternary hybrid composites were fabricated. A carbon layer was directly formed on the surface of Si by the thermal vapor deposition. The carbon-coating layer not only prevented the contact between Si and reactive electrolyte but also provided anchoring sites for the deposition of Fe3O4. Fe3O4 nanoparticles were deposited on the surface of carbon-coated Si by the hydrazine reducing method. The morphology and structure of Fe3O4 and carbon layer were characterized via X-ray diffractometry, field emission scanning electron microscopy, field emission transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analyses. These characterizations indicate that a carbon layer was fully coated on the Si particles, and Fe3O4 particles were homogeneously deposited on the carbon-coated Si particles. The Fe3O4/carbon-coated Si electrode exhibited enhanced electrochemical performance, attributed to the high conductivity and stability of carbon layer and pseudocapacitive reaction of Fe3O4. The proposed ternary-hybrid composites may be potentially useful for the fabrication of high-performance electrodes.

  6. Enhancement of anodic biofilm formation and current output in microbial fuel cells by composite modification of stainless steel electrodes

    NASA Astrophysics Data System (ADS)

    Liang, Yuxiang; Feng, Huajun; Shen, Dongsheng; Li, Na; Guo, Kun; Zhou, Yuyang; Xu, Jing; Chen, Wei; Jia, Yufeng; Huang, Bin

    2017-02-01

    In this paper, we first systematically investigate the current output performance of stainless steel electrodes (SS) modified by carbon coating (CC), polyaniline coating (PANI), neutral red grafting (NR), surface hydrophilization (SDBS), and heat treatment (HEAT). The maximum current density of 13.0 A m-2 is obtained on CC electrode (3.0 A m-2 of the untreated anode). Such high performance should be attributed to its large effective surface area, which is 2.3 times that of the unmodified electrode. Compared with SS electrode, about 3-fold increase in current output is achieved with PANI. Functionalization with hydrophilic group and electron medium result in the current output rising to 1.5-2 fold, through enhancing bioadhesive and electron transport rate, respectively. CC modification is the best choice of single modification for SS electrode in this study. However, this modification is not perfect because of its poor hydrophilicity. So CC electrode is modified by SDBS for further enhancing the current output to 16 A m-2. These results could provide guidance for the choice of suitable single modification on SS electrodes and a new method for the perfection of electrode performance through composite modification.

  7. Design and synthesis of polymer, carbon and composite electrodes for high energy and high power supercapacitors

    NASA Astrophysics Data System (ADS)

    Arcila Velez, Margarita Rosa

    Supercapacitors (SCs) are promising energy storage devices because they deliver energy faster than Li-ion batteries and store larger amounts of charge compared to dielectric capacitors. SCs are classified in electrical double layer capacitors (EDLCs) and pseudocapacitors, based on their charge storage mechanism. EDLCs store charge electrostatically, i.e. by physical charge separation. This mechanism limits the storable amount of energy to the available surface area of the electrode, typically made of carbon materials, but grants good cycling stability of the SC device. Pseudocapacitor electrodes, commonly made of conducting polymers or metal oxides, store charge faradaically, i.e. through redox reactions throughout the bulk material, which allows them to store significantly larger amounts of energy than EDLCs, but their stability is compromised due to the partial irreversibility of the faradaic processes. To accomplish the commercialization of SCs, devices must show a combination of high charge storage capacities and long-term stability, besides being cost-effective. To tackle the current issues of SCs, this field of study has taken mainly two directions: 1) the development of new architectures and nanostructures of the active materials, which has shown to increase the surface area, enhance stability, and facilitate ion diffusion; and 2) fabrication of composites between non-faradaic (carbon), faradaic materials, and/or redox-active components to achieve a balance between the amount of energy stored and the stability. Following the first approach, a continuous process to grow vertically aligned carbon nanotubes (VACNTs) on cost-effective aluminum foil was developed. The resulting electrodes were analyzed as SC electrodes and in symmetric cells, and the influence of the arrangement of the nanotubes and the synthesis conditions was studied. The performance of the VACNTs produced continuously showed similar performance to the VACNTs produced stationarily and the

  8. resterilizable electrode for electrosurgery

    NASA Technical Reports Server (NTRS)

    Engstrom, E. R.; Houge, J. C.

    1979-01-01

    Required properties of flexibility, electrical conductivity, tensile strength, and tear resistance of electrosurgical electrodes is retained through utilization of flexible-polymer/conductive particle composites for electrodes.

  9. Wearable energy-dense and power-dense supercapacitor yarns enabled by scalable graphene-metallic textile composite electrodes

    NASA Astrophysics Data System (ADS)

    Liu, Libin; Yu, You; Yan, Casey; Li, Kan; Zheng, Zijian

    2015-06-01

    One-dimensional flexible supercapacitor yarns are of considerable interest for future wearable electronics. The bottleneck in this field is how to develop devices of high energy and power density, by using economically viable materials and scalable fabrication technologies. Here we report a hierarchical graphene-metallic textile composite electrode concept to address this challenge. The hierarchical composite electrodes consist of low-cost graphene sheets immobilized on the surface of Ni-coated cotton yarns, which are fabricated by highly scalable electroless deposition of Ni and electrochemical deposition of graphene on commercial cotton yarns. Remarkably, the volumetric energy density and power density of the all solid-state supercapacitor yarn made of one pair of these composite electrodes are 6.1 mWh cm-3 and 1,400 mW cm-3, respectively. In addition, this SC yarn is lightweight, highly flexible, strong, durable in life cycle and bending fatigue tests, and integratable into various wearable electronic devices.

  10. α MnMoO₄/graphene hybrid composite: high energy density supercapacitor electrode material.

    PubMed

    Ghosh, Debasis; Giri, Soumen; Moniruzzaman, Md; Basu, Tanya; Mandal, Manas; Das, Chapal Kumar

    2014-07-28

    A unique and cost effective hydrothermal procedure has been carried out for the synthesis of hexahedron shaped α MnMoO4 and its hybrid composite with graphene using three different weight percentages of graphene. Characterization techniques, such as XRD, Raman and FTIR analysis, established the phase and formation of the composite. The electrochemical characterization of the pseudocapacitive MnMoO4 and the MnMoO4/graphene composites in 1 M Na2SO4 displayed highest specific capacitances of 234 F g(-1) and 364 F g(-1), respectively at a current density of 2 A g(-1). Unlike many other pseudocapacitive electrode materials our prepared materials responded in a wide range of working potentials of (-)1 V to (+)1 V, which indeed resulted in a high energy density without substantial loss of power density. The highest energy densities of 130 Wh kg(-1) and 202.2 Wh kg(-1) were achieved, respectively for the MnMoO4 and the MnMoO4/graphene composite at a constant power delivery rate of 2000 W kg(-1). The synergistic effect of the graphene with the pseudocapacitive MnMoO4 caused an increased cycle stability of 88% specific capacitance retention after 1000 consecutive charge discharge cycles at 8 A g(-1) constant current density, which was higher than the virgin MnMoO4 with 84% specific capacitance retention.

  11. Hydrothermal synthesis of nanostructured graphene/polyaniline composites as high-capacitance electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Wang, Ronghua; Han, Meng; Zhao, Qiannan; Ren, Zonglin; Guo, Xiaolong; Xu, Chaohe; Hu, Ning; Lu, Li

    2017-03-01

    As known to all, hydrothermal synthesis is a powerful technique for preparing inorganic and organic materials or composites with different architectures. In this reports, by controlling hydrothermal conditions, nanostructured polyaniline (PANi) in different morphologies were composited with graphene sheets (GNS) and used as electrode materials of supercapacitors. Specifically, ultrathin PANi layers with total thickness of 10–20 nm are uniformly composited with GNS by a two-step hydrothermal-assistant chemical oxidation polymerization process; while PANi nanofibers with diameter of 50~100 nm are obtained by a one-step direct hydrothermal process. Benefitting from the ultrathin layer and porous structure, the sheet-like GNS/PANi composites can deliver specific capacitances of 532.3 to 304.9 F/g at scan rates of 2 to 50 mV/s. And also, this active material showed very good stability with capacitance retention as high as ~99.6% at scan rate of 50 mV/s, indicating a great potential for using in supercapacitors. Furthermore, the effects of hydrothermal temperatures on the electrochemical performances were systematically studied and discussed.

  12. Hydrothermal synthesis of nanostructured graphene/polyaniline composites as high-capacitance electrode materials for supercapacitors.

    PubMed

    Wang, Ronghua; Han, Meng; Zhao, Qiannan; Ren, Zonglin; Guo, Xiaolong; Xu, Chaohe; Hu, Ning; Lu, Li

    2017-03-14

    As known to all, hydrothermal synthesis is a powerful technique for preparing inorganic and organic materials or composites with different architectures. In this reports, by controlling hydrothermal conditions, nanostructured polyaniline (PANi) in different morphologies were composited with graphene sheets (GNS) and used as electrode materials of supercapacitors. Specifically, ultrathin PANi layers with total thickness of 10-20 nm are uniformly composited with GNS by a two-step hydrothermal-assistant chemical oxidation polymerization process; while PANi nanofibers with diameter of 50~100 nm are obtained by a one-step direct hydrothermal process. Benefitting from the ultrathin layer and porous structure, the sheet-like GNS/PANi composites can deliver specific capacitances of 532.3 to 304.9 F/g at scan rates of 2 to 50 mV/s. And also, this active material showed very good stability with capacitance retention as high as ~99.6% at scan rate of 50 mV/s, indicating a great potential for using in supercapacitors. Furthermore, the effects of hydrothermal temperatures on the electrochemical performances were systematically studied and discussed.

  13. Hydrothermal synthesis of nanostructured graphene/polyaniline composites as high-capacitance electrode materials for supercapacitors

    PubMed Central

    Wang, Ronghua; Han, Meng; Zhao, Qiannan; Ren, Zonglin; Guo, Xiaolong; Xu, Chaohe; Hu, Ning; Lu, Li

    2017-01-01

    As known to all, hydrothermal synthesis is a powerful technique for preparing inorganic and organic materials or composites with different architectures. In this reports, by controlling hydrothermal conditions, nanostructured polyaniline (PANi) in different morphologies were composited with graphene sheets (GNS) and used as electrode materials of supercapacitors. Specifically, ultrathin PANi layers with total thickness of 10–20 nm are uniformly composited with GNS by a two-step hydrothermal-assistant chemical oxidation polymerization process; while PANi nanofibers with diameter of 50~100 nm are obtained by a one-step direct hydrothermal process. Benefitting from the ultrathin layer and porous structure, the sheet-like GNS/PANi composites can deliver specific capacitances of 532.3 to 304.9 F/g at scan rates of 2 to 50 mV/s. And also, this active material showed very good stability with capacitance retention as high as ~99.6% at scan rate of 50 mV/s, indicating a great potential for using in supercapacitors. Furthermore, the effects of hydrothermal temperatures on the electrochemical performances were systematically studied and discussed. PMID:28291246

  14. Graphene/heparin template-controlled polyaniline nanofibers composite for high energy density supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Moniruzzaman Sk, Md; Yue, Chee Yoon; Jena, Rajeeb Kumar

    2014-12-01

    Graphene/PANI nanofibers composites are prepared for the first time using a novel in situ polymerization method based on the chemical oxidative polymerization of aniline using heparin as a soft template. The even dispersion of individual graphene sheet within the polymer nanofibers matrix enhances the kinetics for both charge transfer and ion transport throughout the electrode. This novel G25PNF75 composite (weight ratio of GO:PANI = 25:75) shows a high specific capacitance of 890.79 F g-1 and an excellent energy density of 123.81 Wh kg-1 at a constant discharge current of 0.5 mA. The composite exhibits excellent cycle life with 88.78% specific capacitance retention after 1000 charge-discharge cycles. The excellent performance of the composite is due to the synergistic combination of graphene which provides good electrical conductivity and mechanical stability, and PANI nanofiber which provides good redox activity that consequently contributed such high energy density.

  15. Selective Light-Induced Patterning of Carbon Nanotube/Silver Nanoparticle Composite To Produce Extremely Flexible Conductive Electrodes.

    PubMed

    Kim, Inhyuk; Woo, Kyoohee; Zhong, Zhaoyang; Lee, Eonseok; Kang, Dongwoo; Jeong, Sunho; Choi, Young-Man; Jang, Yunseok; Kwon, Sin; Moon, Jooho

    2017-02-22

    Recently, highly flexible conductive features have been widely demanded for the development of various electronic applications, such as foldable displays, deformable lighting, disposable sensors, and flexible batteries. Herein, we report for the first time a selective photonic sintering-derived, highly reliable patterning approach for creating extremely flexible carbon nanotube (CNT)/silver nanoparticle (Ag NP) composite electrodes that can tolerate severe bending (20 000 cycles at a bending radius of 1 mm). The incorporation of CNTs into a Ag NP film can enhance not only the mechanical stability of electrodes but also the photonic-sintering efficiency when the composite is irradiated by intense pulsed light (IPL). Composite electrodes were patterned on various plastic substrates by a three-step process comprising coating, selective IPL irradiation, and wiping. A composite film selectively exposed to IPL could not be easily wiped from the substrate, because interfusion induced strong adhesion to the underlying polymer substrate. In contrast, a nonirradiated film adhered weakly to the substrate and was easily removed, enabling highly flexible patterned electrodes. The potential of our flexible electrode patterns was clearly demonstrated by fabricating a light-emitting diode circuit and a flexible transparent heater with unimpaired functionality under bending, rolling, and folding.

  16. Synthesis of NiMnO3/C nano-composite electrode materials for electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Kakvand, Pejman; Safi Rahmanifar, Mohammad; El-Kady, Maher F.; Pendashteh, Afshin; Kiani, Mohammad Ali; Hashami, Masumeh; Najafi, Mohsen; Abbasi, Ali; Mousavi, Mir F.; Kaner, Richard B.

    2016-08-01

    Demand for high-performance energy storage materials has motivated research activities to develop nano-engineered composites that benefit from both high-rate and high-capacitance materials. Herein, NiMnO3 (NMO) nanoparticles have been synthesized through a facile co-precipitation method. As-prepared NMO samples are then employed for the synthesis of nano-composites with graphite (Gr) and reduced graphene oxide (RGO). Various samples, including pure NMO, NMO-graphite blend, as well as NMO/Gr and NMO/RGO nano-composites have been electrochemically investigated as active materials in supercapacitors. The NMO/RGO sample exhibited a high specific capacitance of 285 F g-1 at a current density of 1 A g-1, much higher than the other samples (237 F g-1 for NMO/Gr, 170 F g-1 for NMO-Gr and 70 F g-1 for NMO). Moreover, the NMO/RGO nano-composite has shown excellent cycle stability with a 93.5% capacitance retention over 1000 cycles at 2 A g-1 and still delivered around 87% of its initial capacitance after cycling for 4000 cycles. An NMO/RGO composite was assessed in practical applications by assembling NMO/RGO//NMO/RGO symmetric devices, exhibiting high specific energy (27.3 Wh kg-1), high specific power (7.5 kW kg-1), and good cycle stability over a broad working voltage of 1.5 V. All the obtained results demonstrate the promise of NMO/RGO nano-composite as a high-performance electrode material for supercapacitors.

  17. Synthesis of NiMnO3/C nano-composite electrode materials for electrochemical capacitors.

    PubMed

    Kakvand, Pejman; Rahmanifar, Mohammad Safi; El-Kady, Maher F; Pendashteh, Afshin; Kiani, Mohammad Ali; Hashami, Masumeh; Najafi, Mohsen; Abbasi, Ali; Mousavi, Mir F; Kaner, Richard B

    2016-08-05

    Demand for high-performance energy storage materials has motivated research activities to develop nano-engineered composites that benefit from both high-rate and high-capacitance materials. Herein, NiMnO3 (NMO) nanoparticles have been synthesized through a facile co-precipitation method. As-prepared NMO samples are then employed for the synthesis of nano-composites with graphite (Gr) and reduced graphene oxide (RGO). Various samples, including pure NMO, NMO-graphite blend, as well as NMO/Gr and NMO/RGO nano-composites have been electrochemically investigated as active materials in supercapacitors. The NMO/RGO sample exhibited a high specific capacitance of 285 F g(-1) at a current density of 1 A g(-1), much higher than the other samples (237 F g(-1) for NMO/Gr, 170 F g(-1) for NMO-Gr and 70 F g(-1) for NMO). Moreover, the NMO/RGO nano-composite has shown excellent cycle stability with a 93.5% capacitance retention over 1000 cycles at 2 A g(-1) and still delivered around 87% of its initial capacitance after cycling for 4000 cycles. An NMO/RGO composite was assessed in practical applications by assembling NMO/RGO//NMO/RGO symmetric devices, exhibiting high specific energy (27.3 Wh kg(-1)), high specific power (7.5 kW kg(-1)), and good cycle stability over a broad working voltage of 1.5 V. All the obtained results demonstrate the promise of NMO/RGO nano-composite as a high-performance electrode material for supercapacitors.

  18. Supercapacitor electrode materials with hierarchically structured pores from carbonization of MWCNTs and ZIF-8 composites.

    PubMed

    Li, Xueqin; Hao, Changlong; Tang, Bochong; Wang, Yue; Liu, Mei; Wang, Yuanwei; Zhu, Yihua; Lu, Chenguang; Tang, Zhiyong

    2017-02-09

    Due to their high specific surface area and good electric conductivity, nitrogen-doped porous carbons (NPCs) and carbon nanotubes (CNTs) have attracted much attention for electrochemical energy storage applications. In the present work, we firstly prepared MWCNT/ZIF-8 composites by decoration of zeolitic imidazolate frameworks (ZIF-8) onto the surface of multi-walled CNTs (MWCNTs), then obtained MWCNT/NPCs by the direct carbonization of MWCNT/ZIF-8. By controlling the reaction conditions, MWCNT/ZIF-8 with three different particle sizes were synthesized. The effect of NPCs size on capacitance performance has been evaluated in detail. The MWCNT/NPC with large-sized NPC (MWCNT/NPC-L) displayed the highest specific capacitance of 293.4 F g(-1) at the scan rate of 5 mV s(-1) and only lost 4.2% of capacitance after 10 000 cyclic voltammetry cycles, which was attributed to the hierarchically structured pores, N-doping and high electrical conductivity. The studies of symmetric two-electrode supercapacitor cells also confirmed MWCNT/NPC-L as efficient electrode materials that have good electrochemical performance, especially for high-rate applications.

  19. Layer by Layer Ex-Situ Deposited Cobalt-Manganese Oxide as Composite Electrode Material for Electrochemical Capacitor

    PubMed Central

    Rusi; Chan, P. Y.; Majid, S. R.

    2015-01-01

    The composite metal oxide electrode films were fabricated using ex situ electrodeposition method with further heating treatment at 300°C. The obtained composite metal oxide film had a spherical structure with mass loading from 0.13 to 0.21 mg cm-2. The structure and elements of the composite was investigated using X-ray diffraction (XRD) and energy dispersive X-ray (EDX). The electrochemical performance of different composite metal oxides was studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (CD). As an active electrode material for a supercapacitor, the Co-Mn composite electrode exhibits a specific capacitance of 285 Fg-1 at current density of 1.85 Ag-1 in 0.5M Na2SO4 electrolyte. The best composite electrode, Co-Mn electrode was then further studied in various electrolytes (i.e., 0.5M KOH and 0.5M KOH/0.04M K3Fe(CN) 6 electrolytes). The pseudocapacitive nature of the material of Co-Mn lead to a high specific capacitance of 2.2 x 103 Fg-1 and an energy density of 309 Whkg-1 in a 0.5MKOH/0.04MK3Fe(CN) 6 electrolyte at a current density of 10 Ag-1. The specific capacitance retention obtained 67% of its initial value after 750 cycles. The results indicate that the ex situ deposited composite metal oxide nanoparticles have promising potential in future practical applications. PMID:26158447

  20. Electrochemical Determination of Chlorpyrifos on a Nano-TiO₂Cellulose Acetate Composite Modified Glassy Carbon Electrode.

    PubMed

    Kumaravel, Ammasai; Chandrasekaran, Maruthai

    2015-07-15

    A rapid and simple method of determination of chlorpyrifos is important in environmental monitoring and quality control. Electrochemical methods for the determination of pesticides are fast, sensitive, reproducible, and cost-effective. The key factor in electrochemical methods is the choice of suitable electrode materials. The electrode materials should have good stability, reproducibility, more sensitivity, and easy method of preparation. Mercury-based electrodes have been widely used for the determination of chlorpyrifos. From an environmental point of view mercury cannot be used. In this study a biocompatible nano-TiO2/cellulose acetate modified glassy carbon electrode was prepared by a simple method and used for the electrochemical sensing of chlorpyrifos in aqueous methanolic solution. Electroanalytical techniques such as cyclic voltammetry, differential pulse voltammetry, and amperometry were used in this work. This electrode showed very good stability, reproducibility, and sensitivity. A well-defined peak was obtained for the reduction of chlorpyrifos in cyclic voltammetry and differential pulse voltammetry. A smooth noise-free current response was obtained in amperometric analysis. The peak current obtained was proportional to the concentration of chlorpyrifos and was used to determine the unknown concentration of chlorpyrifos in the samples. Analytical parameters such as LOD, LOQ, and linear range were estimated. Analysis of real samples was also carried out. The results were validated through HPLC. This composite electrode can be used as an alternative to mercury electrodes reported in the literature.

  1. An electrochemiluminescent sensor for methamphetamine hydrochloride based on multiwall carbon nanotube/ionic liquid composite electrode.

    PubMed

    Dai, Hong; Wang, Youmei; Wu, Xiaoping; Zhang, Lan; Chen, Guonan

    2009-01-01

    In this article, a composite paste electrode consisted of multiwall carbon nanotube (MWCNT) and room temperature ionic liquids (RTILs) was developed for fabrication of electrochemiluminescence (ECL) sensor. The electrochemical and ECL behaviors of this sensor were investigated in detail. This ECL sensor exhibited extraordinary stability during long-term potential cycling. It was found that the light emission of this ECL sensor could be enhanced by methamphetamine hydrochloride (MA.HCl) dramatically. Based on which, a new method based on this ECL sensor has been developed for determination of MA.HCl. The method exhibited a good reproducibility, wide-range linearity, high sensitivity and stability with a detection limit (signal-to-noise ratio=3) of 8.0 x 10(-9)mol/L, and the relative standard deviation was 3.1% for 1 x 10(-5)mol/L MA.HCl (n=10).

  2. High-performance supercapacitors based on freestanding carbon-based composite paper electrodes

    NASA Astrophysics Data System (ADS)

    Yun, Young Soo; Lee, Min Eui; Joo, Min Jae; Jin, Hyoung-Joon

    2014-01-01

    Using a simple filtration method, we fabricate freestanding carbon-based composite paper electrodes (F-CCPEs), based on acid-treated carbon nanotubes (a-CNTs) and microporous carbon-based nanoplates containing numerous heteroatoms (H-CMNs). The F-CCPEs exhibited a high electrical conductivity of 2.3 × 102 S cm-1 and a high surface area of 1211.7 m2 g-1; moreover, they had numerous electroative heteroatoms and showed mechanical flexibility. Therefore, F-CCPEs without current collectors and binder show a superior electrochemical performance. In particular, the prepared F-CCPEs exhibit high capacitances of 275 and 148 F g-1 in aqueous and organic electrolytes, respectively. In addition, the specific energy density and specific power density of these F-CCPEs were found to be 63 Wh kg-1 and 140 kW kg-1, respectively, with good cyclic stability, even after 20,000 charge/discharge cycles.

  3. Nano-composite Si particle formation by plasma spraying for negative electrode of Li ion batteries

    NASA Astrophysics Data System (ADS)

    Kambara, M.; Kitayama, A.; Homma, K.; Hideshima, T.; Kaga, M.; Sheem, K.-Y.; Ishida, S.; Yoshida, T.

    2014-04-01

    Nano-composite silicon powders have been produced at a maximum process throughput of 6 g/min by plasma spraying with metallurgical grade silicon powder as raw material. The obtained powders are found to be fundamentally composed of crystalline silicon particles of 20-40 nm in diameter, and are coated with an ˜5-nm-thick amorphous carbonous layer when methane gas is additionally introduced during plasma spraying. The performance of half-cell batteries containing the powders as negative electrodes has shown that the capacity decay observed for the raw Si coarse particles is significantly improved by plasma treatment. The carbonous coating potentially contributes to an improvement in capacity retention, although coexisting SiC particles that inevitably form during high-temperature processing reduce the overall capacity.

  4. Preparation and electrochemical analysis of electrodeposited MnO2/C composite for advanced capacitor electrode

    NASA Astrophysics Data System (ADS)

    Kim, In-Tae; Kouda, Nobuo; Yoshimoto, Nobuko; Morita, Masayuki

    2015-12-01

    Mesoporous carbon (MPC) with uniform inner mesopore structure and high specific surface area prepared by an MgO-templated method has been employed for a substrate of MnO2/C composite. The MnO2/C composite was synthesized by anodic or cathodic electrodeposition of MnO2 from MnSO4 or KMnO4 precursor, respectively, on the MPC substrate. The XRD patterns of the composite confirmed that MnO2 was effectively deposited on the substrate under both anodic and cathodic electrodeposition processes. From the SEM images, sheet-like MnO2 was deposited by anodic deposition (a-MnO2/C) while needle-like MnO2 deposition was observed for the cathodic deposition (c-MnO2/C). The voltammetric experiments showed that the capacitive behavior of the composite depended on the preparation method. The difference in the specific capacitance between a-MnO2/C and c-MnO2/C is considered to be mainly due to the shape of MnO2 deposited on the MPC substrate. The electrochemical capacitance of c-MnO2/C was much higher than that of the substrate carbon. The observed capacitance increase in c-MnO2/C was attributed to the pseudo-capacitance of MnO2 that utilized effectively in controlled pore structure of MPC. The composite electrode, prepared by the cathodic deposition (c-MnO2/C), showed high specific capacitance and good durability for constant-current charge-discharge cycling.

  5. Robust myoelectric signal detection based on stochastic resonance using multiple-surface-electrode array made of carbon nanotube composite paper

    NASA Astrophysics Data System (ADS)

    Shirata, Kento; Inden, Yuki; Kasai, Seiya; Oya, Takahide; Hagiwara, Yosuke; Kaeriyama, Shunichi; Nakamura, Hideyuki

    2016-04-01

    We investigated the robust detection of surface electromyogram (EMG) signals based on the stochastic resonance (SR) phenomenon, in which the response to weak signals is optimized by adding noise, combined with multiple surface electrodes. Flexible carbon nanotube composite paper (CNT-cp) was applied to the surface electrode, which showed good performance that is comparable to that of conventional Ag/AgCl electrodes. The SR-based EMG signal system integrating an 8-Schmitt-trigger network and the multiple-CNT-cp-electrode array successfully detected weak EMG signals even when the subject’s body is in the motion, which was difficult to achieve using the conventional technique. The feasibility of the SR-based EMG detection technique was confirmed by demonstrating its applicability to robot hand control.

  6. Voltammetric determination of ferulic acid by didodecyldimethylammonium bromide/nafion composite film-modified carbon paste electrode.

    PubMed

    Luo, Liqiang; Wang, Xia; Li, Qiuxia; Ding, Yaping; Jia, Jianbo; Deng, Dongmei

    2010-01-01

    A simple and rapid method for the determination of ferulic acid in pharmaceutical formulations by didodecyldimethylammonium bromide (DDAB)/Nafion composite film-modified carbon paste electrode is presented. The electrochemical behavior of ferulic acid at the proposed electrode was investigated by cyclic voltammetry and a well-defined oxidation peak was observed at +0.44 V versus saturated calomel electrode in 0.1 M acetate buffer (pH 5.5) solutions. Some experimental parameters affecting the electrochemical response of the modified electrode were optimized. Under optimal conditions, the oxidation peak currents of ferulic acid increase linearly with the concentration of ferulic acid in the range from 2.0 x 10(-6) to 1.2 x 10(-4) M with a detection limit of 3.9 x 10(-7) M (S/N = 3). The proposed method was successfully applied to the determination of ferulic acid in pharmaceutical tablets.

  7. Choline-sensing carbon paste electrode containing polyaniline (pani)-silicon dioxide composite-modified choline oxidase.

    PubMed

    Özdemir, Merve; Arslan, Halit

    2014-02-01

    In this study, a novel carbon paste electrode (CPE) was prepared using the salt form of polyaniline (pani)-silicon dioxide composite that is sensitive to choline. Choline oxidase (ChO) enzyme was immobilized to modified carbon paste electrode (MCPE) by cross-linking with glutaraldehyde. Determination of choline was carried out by the oxidation of enzymatically produced H2O2 at 0.4 V vs. Ag/AgCl. The effects of pH and temperature were investigated, and the optimum parameters were found to be 6.0 and 60°C, respectively. The linear working range of the electrode was 5.0 × 10(-7)-1.0 × 10(-5) M, R(2) = 0.922. The storage stability and operation stability of the enzyme electrode were also studied.

  8. Surface characteristics of Ti-6Al-4V alloy by EDM with Cu-SiC composite electrode

    NASA Astrophysics Data System (ADS)

    Li, L.; Feng, L.; Bai, X.; Li, Z. Y.

    2016-12-01

    Ti-6Al-4V alloy is widely used in many industries due to its outstanding properties. However, it has poor machinability using conventional mechanical cutting process. Electrical discharge machining is an alternative competitive process to machine titanium alloy by electrical erosion. This article studies the machining characteristics of Ti-6Al-4V with Cu-SiC composite electrode. Surface topography, subsurface microstructure, energy dispersive spectroscopy analysis, and micro-hardness have been analyzed. The machined surfaces show irregular compound structures, droplets of debris, shallow craters, and micro-pores. The surfaces processed by Cu-SiC electrode have fewer number of microcracks compared with that by Cu electrode. Continuous and uniform hardened layer can be achieved by Cu-SiC electrode. The hardened layer has significantly higher hardness than the bulk material because the new phases of TiC and TiSi2 were created on the surface.

  9. Voltammetric Detection of Urea on an Ag-Modified Zeolite-Expanded Graphite-Epoxy Composite Electrode

    PubMed Central

    Manea, Florica; Pop, Aniela; Radovan, Ciprian; Malchev, Plamen; Bebeselea, Adriana; Burtica, Georgeta; Picken, Stephen; Schoonman, Joop

    2008-01-01

    In this paper, a modified expanded graphite composite electrode based on natural zeolitic volcanic tuff modified with silver (EG-Ag-Z-Epoxy) was developed. Cyclic voltammetry measurements revealed a reasonably fast electron transfer and a good stability of the electrode in 0.1 M NaOH supporting electrolyte. This modified electrode exhibited moderate electrocatalytic effect towards urea oxidation, allowing its determination in aqueous solution. The linear dependence of the current versus urea concentration was reached using square-wave voltammetry in the concentrations range of urea between 0.2 to 1.4 mM, with a relatively low limit of detection of 0.05 mM. A moderate enhancement of electroanalytical sensitivity for the determination of urea at EG-Ag-Z-Epoxy electrode was reached by applying a chemical preconcentration step prior to voltammetric/amperometric quantification. PMID:27873841

  10. Impedance spectroscopic analysis of composite electrode from activated carbon/conductive materials/ruthenium oxide for supercapacitor applications

    SciTech Connect

    Taer, E.; Awitdrus,; Farma, R.; Deraman, M. Talib, I. A.; Ishak, M. M.; Omar, R.; Dolah, B. N. M.; Basri, N. H.; Othman, M. A. R.; Kanwal, S.

    2015-04-16

    Activated carbon powders (ACP) were produced from the KOH treated pre-carbonized rubber wood sawdust. Different conductive materials (graphite, carbon black and carbon nanotubes (CNTs)) were added with a binder (polivinylidene fluoride (PVDF)) into ACP to improve the supercapacitive performance of the activated carbon (AC) electrodes. Symmetric supercapacitor cells, fabricated using these AC electrodes and 1 molar H{sub 2}SO{sub 4} electrolyte, were analyzed using a standard electrochemical impedance spectroscopy technique. The addition of graphite, carbon black and CNTs was found effective in reducing the cell resistance from 165 to 68, 23 and 49 Ohm respectively, and increasing the specific capacitance of the AC electrodes from 3 to 7, 17, 32 F g{sup −1} respectively. Since the addition of CNTs can produce the highest specific capacitance, CNTs were chosen as a conductive material to produce AC composite electrodes that were added with 2.5 %, 5 % and 10 % (by weight) electro-active material namely ruthenium oxide; PVDF binder and CNTs contents were kept at 5 % by weight in each AC composite produced. The highest specific capacitance of the cells obtained in this study was 86 F g{sup −1}, i.e. for the cell with the resistance of 15 Ohm and composite electrode consists of 5 % ruthenium oxide.

  11. Optimum electrode configuration selection for electrical resistance change based damage detection in composites using an effective independence measure

    NASA Astrophysics Data System (ADS)

    Escalona, Luis; Díaz-Montiel, Paulina; Venkataraman, Satchi

    2016-04-01

    Laminated carbon fiber reinforced polymer (CFRP) composite materials are increasingly used in aerospace structures due to their superior mechanical properties and reduced weight. Assessing the health and integrity of these structures requires non-destructive evaluation (NDE) techniques to detect and measure interlaminar delamination and intralaminar matrix cracking damage. The electrical resistance change (ERC) based NDE technique uses the inherent changes in conductive properties of the composite to characterize internal damage. Several works that have explored the ERC technique have been limited to thin cross-ply laminates with simple linear or circular electrode arrangements. This paper investigates a method of optimum selection of electrode configurations for delamination detection in thick cross-ply laminates using ERC. Inverse identification of damage requires numerical optimization of the measured response with a model predicted response. Here, the electrical voltage field in the CFRP composite laminate is calculated using finite element analysis (FEA) models for different specified delamination size and locations, and location of ground and current electrodes. Reducing the number of sensor locations and measurements is needed to reduce hardware requirements, and computational effort needed for inverse identification. This paper explores the use of effective independence (EI) measure originally proposed for sensor location optimization in experimental vibration modal analysis. The EI measure is used for selecting the minimum set of resistance measurements among all possible combinations of selecting a pair of electrodes among the n electrodes. To enable use of EI to ERC required, it is proposed in this research a singular value decomposition SVD to obtain a spectral representation of the resistance measurements in the laminate. The effectiveness of EI measure in eliminating redundant electrode pairs is demonstrated by performing inverse identification of

  12. Nanostructured TiO2-coated activated carbon composite as an electrode material for asymmetric hybrid capacitors.

    PubMed

    Kim, Sang-Ok; Lee, Joong Kee

    2012-02-01

    A nanostructured TiO2-coated activated carbon (TAC) composite was synthesized by a modified sol-gel reaction and employed it as a negative electrode active material for an asymmetric hybrid capacitor. The structural characterization showed that the TiO2 nano-layer was deposited on the surface of the activated carbon and the TAC composite has a highly mesoporous structure. The evaluation of electrochemical characteristics of the TAC electrode was carried out by galvanostatic charge/discharge cycling tests and electrochemical impedance spectroscopy. The obtained specific capacitance of the TAC composite was 42.87 F/g, which showed by 27.1% higher than that of the activated carbon (AC). The TAC composite also exhibited an excellent cycle performance and kept 95% of initial capacitance over 500 cycles.

  13. Li/Ag2VO2PO4 batteries: the roles of composite electrode constituents on electrochemistry

    SciTech Connect

    Bock, David C.; Bruck, Andrea M.; Pelliccione, Christopher J.; Zhang, Yiman; Takeuchi, Kenneth J.; Marschilok, Amy C.; Takeuchi, Esther S.

    2016-11-01

    Silver vanadium phosphorous oxide, Ag2V2OPO4, was used as a model system to systematically study the impact on the constituents of a composite electrode, including polymeric and conductive additives, on electrochemistry. Three different electrode compositions were investigated.

  14. Graphite-Teflon composite bienzyme electrodes for the determination of L-lactate: application to food samples.

    PubMed

    Serra, B; Reviejo, A J; Parrado, C; Pingarrón, J M

    1999-05-31

    A bienzyme amperometric graphite-Teflon composite biosensor, in which lactate oxidase (LOD) and peroxidase, together with the mediator ferrocene, are incorporated into the electrode matrix, was developed for the determination of L-lactate in food samples such as wine and yogurt by using both batch- and flow-injection modes. This bienzyme electrode was fabricated by simple physical inclusion of the enzymes and the mediator in the bulk of the graphite-Teflon matrix. A Teflon content of 70%, an applied potential of 0.00 V, and a pH of 7.4 were employed as working conditions. The composite bioelectrode exhibited long-term operation because of the renewability of its surface by polishing. Reproducible amperometric responses were achieved with different electrodes fabricated from different composite matrices, and no significant loss of the enzyme activity occurred after 6 months of storage at 4 degrees C. Detection limits for L-lactate of 1.4 and 0.9 microM were obtained by batch amperometry in stirred solutions and flow-injection with amperometric detection, respectively. An interferences study with different substances which may be present in wine and yogurt together with L-lactic acid demonstrated very good selectivity for the determination of this analyte. The bienzyme composite electrode was applied to the determination of L-lactic acid in red wine and shaken yogurt, and the methods were validated by comparing these results with those obtained by applying a recommended reference method.

  15. VISCOSITY AND BINDER COMPOSITION EFFECTS ON TYROSINASE-BASED CARBON PASTE ELECTRODE FOR DETECTION OF PHENOL AND CATECHOL

    EPA Science Inventory

    The systematic study of the effect of binder viscosity on the sensitivity of a tyrosinase-based carbon paste electrode (CPE) biosensor for phenol and catechol is reported. Silicon oil binders with similar (polydimethylsiloxane) chemical composition were used to represent a wid...

  16. Amorphous vanadyl phosphate/graphene composites for high performance supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Chen, Ningna; Zhou, Jinhua; Kang, Qi; Ji, Hongmei; Zhu, Guoyin; Zhang, Yu; Chen, Shanyong; Chen, Jing; Feng, Xiaomiao; Hou, Wenhua

    2017-03-01

    Amorphous vanadyl phosphate/graphene nanohybrids is successfully synthesized by first exfoliating bulk layered vanadyl phosphate (VOPO4·2H2O) into nanosheets, and then hydrothermal treatment with graphene oxide (GO). The electrochemical properties of the resulted materials are systematically investigated. It is found that a phase transformation from crystalline to amorphous is occurred to VOPO4·2H2O. As supercapacitor electrode material, the amorphous VOPO4/graphene composite exhibits a high specific capacitance (508 F g-1 at 0.5 A g-1), an excellent rate capability (359 F g-1 at 10 A g-1), and a good cycling stability (retention 80% after 5000 cycles at 2 A g-1). Particularly, it simultaneously has a greatly enhanced energy density of 70.6 Wh·kg-1 with a power density of 250 W kg-1. The outstanding energy storage performance mainly originates from the generation of amorphous VOPO4 phase that facilitates ion transport by shortening ion diffusion paths and provides more reversible and fast faradic reaction sites, the hybridization with graphene that greatly improves the electric conductivity and structure stability, and the unique layer-on-sheet nanohybrid structure that effectively enhances the structure integrity. This work not only provides a facile method for the preparation of amorphous VOPO4/graphene composites, but also demonstrates the enhanced energy density and rate capability of amorphous VOPO4-based materials for potential application in supercapacitors.

  17. Development of amperometric biosensors based on nanostructured tyrosinase-conducting polymer composite electrodes.

    PubMed

    Lupu, Stelian; Lete, Cecilia; Balaure, Paul Cătălin; Caval, Dan Ion; Mihailciuc, Constantin; Lakard, Boris; Hihn, Jean-Yves; Javier del Campo, Francisco

    2013-05-21

    Bio-composite coatings consisting of poly(3,4-ethylenedioxythiophene) (PEDOT) and tyrosinase (Ty) were successfully electrodeposited on conventional size gold (Au) disk electrodes and microelectrode arrays using sinusoidal voltages. Electrochemical polymerization of the corresponding monomer was carried out in the presence of various Ty amounts in aqueous buffered solutions. The bio-composite coatings prepared using sinusoidal voltages and potentiostatic electrodeposition methods were compared in terms of morphology, electrochemical properties, and biocatalytic activity towards various analytes. The amperometric biosensors were tested in dopamine (DA) and catechol (CT) electroanalysis in aqueous buffered solutions. The analytical performance of the developed biosensors was investigated in terms of linear response range, detection limit, sensitivity, and repeatability. A semi-quantitative multi-analyte procedure for simultaneous determination of DA and CT was developed. The amperometric biosensor prepared using sinusoidal voltages showed much better analytical performance. The Au disk biosensor obtained by 50 mV alternating voltage amplitude displayed a linear response for DA concentrations ranging from 10 to 300 μM, with a detection limit of 4.18 μM.

  18. Effect of percolation on the capacitance of supercapacitor electrodes prepared from composites of manganese dioxide nanoplatelets and carbon nanotubes.

    PubMed

    Higgins, Thomas M; McAteer, David; Coelho, João Carlos Mesquita; Mendoza Sanchez, Beatriz; Gholamvand, Zahra; Moriarty, Greg; McEvoy, Niall; Berner, Nina Christina; Duesberg, Georg Stefan; Nicolosi, Valeria; Coleman, Jonathan N

    2014-09-23

    Here we demonstrate significant improvements in the performance of supercapacitor electrodes based on 2D MnO2 nanoplatelets by the addition of carbon nanotubes. Electrodes based on MnO2 nanoplatelets do not display high areal capacitance because the electrical properties of such films are poor, limiting the transport of charge between redox sites and the external circuit. In addition, the mechanical strength is low, limiting the achievable electrode thickness, even in the presence of binders. By adding carbon nanotubes to the MnO2-based electrodes, we have increased the conductivity by up to 8 orders of magnitude, in line with percolation theory. The nanotube network facilitates charge transport, resulting in large increases in capacitance, especially at high rates, around 1 V/s. The increase in MnO2 specific capacitance scaled with nanotube content in a manner fully consistent with percolation theory. Importantly, the mechanical robustness was significantly enhanced, allowing the fabrication of electrodes that were 10 times thicker than could be achieved in MnO2-only films. This resulted in composite films with areal capacitances up to 40 times higher than could be achieved with MnO2-only electrodes.

  19. Cerium oxide nanoparticles/multi-wall carbon nanotubes composites: Facile synthesis and electrochemical performances as supercapacitor electrode materials

    NASA Astrophysics Data System (ADS)

    Deng, Dongyang; Chen, Nan; Li, Yuxiu; Xing, Xinxin; Liu, Xu; Xiao, Xuechun; Wang, Yude

    2017-02-01

    Cerium oxide nanoparticles/multi-wall carbon nanotubes (MWCNTs) composites are synthesized by a facile hydrothermal method without any surfactant or template. The morphology and microstructure of samples are examined by scanning electron microscopy (SEM), transition electron microscopy (TEM), X-ray diffraction (XRD), Raman spectrum and X-ray photoelectron spectroscopy (XPS). Electrochemical properties of the MWCNTs, the pure CeO2, and the CeO2/MWCNTs nanocomposites electrodes are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge (GDC) and electrochemical impedance spectroscopy (EIS) measurements. The CeO2/MWCNTs nanocomposite (at the mole ratio of 1:1) electrode exhibits much larger specific capacitance compared with both the MWCNTs electrode and the pure CeO2 electrode and significantly improves cycling stability compared to the pure CeO2 electrode. The CeO2/MWCNTs nanocomposite (at the mole ratio of 1:1) achieves a specific capacitance of 455.6 F g-1 at the current density of 1 A g-1. Therefore, the as prepared CeO2/MWCNTs nanocomposite is a promising electrode material for high-performance supercapacitors.

  20. Highly Flexible and Conductive Cellulose-Mediated PEDOT:PSS/MWCNT Composite Films for Supercapacitor Electrodes.

    PubMed

    Zhao, Dawei; Zhang, Qi; Chen, Wenshuai; Yi, Xin; Liu, Shouxin; Wang, Qingwen; Liu, Yixing; Li, Jian; Li, Xianfeng; Yu, Haipeng

    2017-04-05

    Recent improvements in flexible electronics have increased the need to develop flexible and lightweight power sources. However, current flexible electrodes are limited by low capacitance, poor mechanical properties, and lack of cycling stability. In this article, we describe an ionic liquid-processed supramolecular assembly of cellulose and 3,4-ethylenedioxythiophene for the formation of a flexible and conductive cellulose/poly(3,4-ethylenedioxythiophene) PEDOT:poly(styrene sulfonate) (PSS) composite matrix. On this base, multiwalled carbon nanotubes (MWCNTs) were incorporated into the matrix to fabricate an MWCNT-reinforced cellulose/PEDOT:PSS film (MCPP), which exhibited favorable flexibility and conductivity. The MCPP-based electrode displayed comprehensively excellent electrochemical properties, such as a low resistance of 0.45 Ω, a high specific capacitance of 485 F g(-1) at 1 A g(-1), and good cycling stability, with a capacity retention of 95% after 2000 cycles at 2 A g(-1). An MCPP-based symmetric solid-state supercapacitor with Ni foam as the current collector and PVA/KOH gel as the electrolyte exhibited a specific capacitance of 380 F g(-1) at 0.25 A g(-1) and achieved a maximum energy density of 13.2 Wh kg(-1) (0.25 A g(-1)) with a power density of 0.126 kW kg(-1) or an energy density of 4.86 Wh kg(-1) at 10 A g(-1), corresponding to a high power density of 4.99 kW kg(-1). Another kind of MCPP-based solid-state supercapacitor without the Ni foam showed excellent flexibility and a high volumetric capacitance of 50.4 F cm(-3) at 0.05 A cm(-3). Both the electrodes and the supercapacitors were environmentally stable and could be operated under remarkable deformation or high temperature without damage to their structural integrity or a significant decrease in capacitive performance. Overall, this work provides a strategy for the fabrication of flexible and conductive energy-storage films with ionic liquid-processed cellulose as a medium.

  1. Review on advances in porous nanostructured nickel oxides and their composite electrodes for high-performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Sk, Md Moniruzzaman; Yue, Chee Yoon; Ghosh, Kalyan; Jena, Rajeeb Kumar

    2016-03-01

    Recently, porous nanostructured transition metal oxides with excellent electrochemical performance have become a new class of energy storage materials for supercapacitors. The ever-growing global demand of electrically powered devices makes it imperative to develop renewable, efficient and reliable electrochemical energy storage devices. This review article focuses on the Ni based transition metal oxides and their composite electrode materials including carbons, metals and transition metal oxides for supercapacitor applications, providing an overview on the charge mechanisms, methodologies and nanostructures discovered in recent years, and latest research findings. The NiO and their composites possess higher reversible capacity, good structural stability, and have been studied for usage as novel electrode materials for supercapacitors. Their fine-tuned physical and chemical properties make them ideal candidates for supercapacitor applications as they possess higher accessible electroactive sites, which will provide both high power density and also high energy density. Moreover, synergistic effects can be derived from the constituent materials of the NiO based composite electrodes. The potential problems like device fabrication, measurement techniques, and future prospects of utilizing these materials as supercapacitor electrodes highlighting the fundamental understanding of the relationship between electrochemical and structural performances are also discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  3. Solution-processed Ag-nanowire/ZnO-nanoparticle composite transparent electrode for flexible organic solar cells.

    PubMed

    Wei, Bin; Pan, Saihu; Wang, Taohong; Tian, Zhenghao; Chen, Guo; Xu, Tao

    2016-12-16

    This paper demonstrates a hybrid transparent electrode composed of a solution-processed silver-nanowire (AgNW) film coated by zinc oxide nanoparticles (ZnO-NPs) acting as a modified buffer layer. The effect of the ZnO-NPs' coating ratio on the performances of indium tin oxide (ITO)-free organic solar cells (OSCs) has been systematically investigated. The optimized ITO-free OSCs achieved a power conversion efficiency (PCE) of 2.85%, while flexible OSCs using the AgNW/ZnO-NP composite transparent electrode grown on a polyethylene terephthalate (PET) substrate showed a PCE of 2.2%.

  4. Solution-processed Ag-nanowire/ZnO-nanoparticle composite transparent electrode for flexible organic solar cells

    NASA Astrophysics Data System (ADS)

    Wei, Bin; Pan, Saihu; Wang, Taohong; Tian, Zhenghao; Chen, Guo; Xu, Tao

    2016-12-01

    This paper demonstrates a hybrid transparent electrode composed of a solution-processed silver-nanowire (AgNW) film coated by zinc oxide nanoparticles (ZnO-NPs) acting as a modified buffer layer. The effect of the ZnO-NPs’ coating ratio on the performances of indium tin oxide (ITO)-free organic solar cells (OSCs) has been systematically investigated. The optimized ITO-free OSCs achieved a power conversion efficiency (PCE) of 2.85%, while flexible OSCs using the AgNW/ZnO-NP composite transparent electrode grown on a polyethylene terephthalate (PET) substrate showed a PCE of 2.2%.

  5. Preparation and characterization of nanostructured NiO/MnO{sub 2} composite electrode for electrochemical supercapacitors

    SciTech Connect

    Liu Enhui Li Wen; Li Jian; Meng Xiangyun; Ding Rui; Tan Songting

    2009-05-06

    Nanostructured nickel-manganese oxides composite was prepared by the sol-gel and the chemistry deposition combination new route. The surface morphology and structure of the composite were characterized by scanning electron microscope and X-ray diffraction. The as-synthesized NiO/MnO{sub 2} samples exhibit higher surface area of 130-190 m{sup 2} g{sup -1}. Cyclic voltammetry and galvanostatic charge/discharge measurements were applied to investigate the electrochemical performance of the composite electrodes with different ratios of NiO/MnO{sub 2}. When the mass ratio of MnO{sub 2} and NiO in composite material is 80:20, the specific capacitance value of NiO/MnO{sub 2} calculated from the cyclic voltammetry curves is 453 F g{sup -1}, for pure NiO and MnO{sub 2} are 209, 330 F g{sup -1} in 6 mol L{sup -1} KOH electrolyte and at scan rate of 10 mV s{sup -1}, respectively. The specific capacitance of NiO/MnO{sub 2} electrode is much larger than that of each pristine component. Moreover, the composite electrodes showed high power density and stable electrochemical properties.

  6. Preparation and characterization of composite electrodes of coconut-shell-based activated carbon and hydrous ruthenium oxide for supercapacitors

    NASA Astrophysics Data System (ADS)

    Dandekar, Mukta S.; Arabale, Girish; Vijayamohanan, K.

    The relationship between the structure-specific capacitance (F g -1) of a composite electrode consisting of activated coconut-shell carbon and hydrous ruthenium oxide (RuO x(OH) y) has been evaluated by impregnating various amounts of RuO x(OH) y into activated carbon that is specially prepared with optimum pore-size distribution. The composite electrode shows an enhanced specific capacitance of 250 F g -1 in 1 M H 2SO 4 with 9 wt.% ruthenium incorporated. Chemical and structural characterization of the composites reveals a homogeneous distribution of amorphous RuO x(OH) y throughout the porous network of the activated carbon. Electrochemical characterization indicates an almost linear dependence of capacitance on the amount of ruthenium owing to its pseudocapacitive nature.

  7. Bridging Oriented Copper Nanowire-Graphene Composites for Solution-Processable, Annealing-Free, and Air-Stable Flexible Electrodes.

    PubMed

    Zhang, Wang; Yin, Zhenxing; Chun, Alvin; Yoo, Jeeyoung; Kim, Youn Sang; Piao, Yuanzhe

    2016-01-27

    One-dimensional flexible metallic nanowires (NWs) are of considerable interest for next-generation wearable devices. The unavoidable challenge for a wearable electrode is the assurance of high conductivity, flexibility, and durability with economically feasible materials and simple manufacturing processes. Here, we use a straightforward solvothermal method to prepare a flexible conductive material that contains reduced graphene oxide (RGO) nanosheets bridging oriented copper NWs. The GO-assistance route can successfully meet the criteria listed above and help the composite films maintain high conductivity and durable flexibility without any extra treatment, such as annealing or acid processes. The composite film exhibits a high electrical performance (0.808 Ω·sq(-1)) without considerable change over 30 days under ambient conditions. Moreover, the Cu NW-RGO composites can be deposited on polyester cloth as a lightweight wearable electrode with high durability and simple processability and are very promising for a wide variety of electronic devices.

  8. Fabrication of Sc2O3-magneli phase titanium composite electrode and its application in efficient electrocatalytic degradation of methyl orange

    NASA Astrophysics Data System (ADS)

    Bai, Hongmei; He, Ping; Chen, Jingchao; Liu, Kaili; Lei, Hong; Dong, Faqin; Zhang, Xingquan; Li, Hong

    2017-04-01

    Sc2O3-magneli phase titanium (Sc2O3-MPT) composite electrode was successfully fabricated via a simple pressing-sintering method and used for electrocatalytic degradation of methyl orange (MO). It was shown that Sc2O3 was successfully composited with MPT. Compared with MPT electrode, Sc2O3-MPT composite electrode had less spherical particles and more pores. Linear scanning voltammetry indicated that Sc2O3-MPT composite electrode presented higher oxygen evolution overpotential than MPT electrode, suggesting that Sc2O3-MPT electrode was much more suitable for the degradation of MO. The electrocatalytic degradation of MO was evaluated under different parameters including current density, temperature, initial pH and electrolysis time. Under the optimal parameters (current density 10 mA cm-2, temperature 25 °C, initial pH 3 and electrolysis time 120 min), the degradation efficiency of MO on Sc2O3-MPT composite electrode reached up to 90.16%. All these results demonstrated that Sc2O3-MPT composite electrode was effective for electrocatalytic degradation of MO and had a great potential application in the treatment of dyes wastewater.

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

    PubMed

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

    2014-05-20

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

  10. Highly transparent low resistance ZnO/Ag nanowire/ZnO composite electrode for thin film solar cells.

    PubMed

    Kim, Areum; Won, Yulim; Woo, Kyoohee; Kim, Chul-Hong; Moon, Jooho

    2013-02-26

    We present an indium-free transparent conducting composite electrode composed of silver nanowires (AgNWs) and ZnO bilayers. The AgNWs form a random percolating network embedded between the ZnO layers. The unique structural features of our ZnO/AgNW/ZnO multilayered composite allow for a novel transparent conducting electrode with unprecedented excellent thermal stability (∼375 °C), adhesiveness, and flexibility as well as high electrical conductivity (∼8.0 Ω/sq) and good optical transparency (>91% at 550 nm). Cu(In,Ga)(S,Se)₂ (CIGSSe) thin film solar cells incorporating this composite electrode exhibited a 20% increase of the power conversion efficiency compared to a conventional sputtered indium tin oxide-based CIGSSe solar cell. The ZnO/AgNW/ZnO composite structure enables effective light transmission and current collection as well as a reduced leakage current, all of which lead to better cell performance.

  11. MnO 2-Pt/C composite electrodes for preventing voltage reversal effects with polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Wei, Z. D.; Ji, M. B.; Hong, Y.; Sun, C. X.; Chan, S. H.; Shen, P. K.

    Water is produced at the cathode of proton-exchange membrane fuel cells (PEMFC). If water were not being removed effectively, it would accumulate at the cathode of PEMFC causing the electrode flooding. The consequence is oxygen starvation, thus increasing the concentration overpotential of the cathode. In the worst scenarios, a proton (H +) reduction reaction (PRR), instead of the oxygen reduction reaction (ORR), might occur at the cathode. Not only will this cause a cathode potential drop, but the output voltage of a single cell would likely be reversed due to oxygen starvation. This phenomenon is termed the voltage reversal effect (VRE) in this paper. To study and resolve the VRE problem, a MnO 2-Pt/C composite electrode was used to replace the conventional Pt/C electrode. The authors suggest that the electrochemical reduction of MnO 2 in the composite electrode has almost the same Nernstian potential as the ORR, which would serve as a substitute for the ORR in the case of oxygen starvation. Thus, the voltage reversal effect caused by the PRR could be avoided. Two environments, N 2- and O 2-saturated H 2SO 4, were adopted to simulate two cases, i.e., O 2 starvation and O 2 rich. It was found that MnO 2-Pt/C can prevent the voltage reversal effect to a certain extent. In a N 2-saturated 1 M H 2SO 4 solution, the current density of the Pt/C electrode made of 0.6 mg Pt cm -2 was close to 0, while for the MnO 2-Pt/C composite electrode made of 0.4 mg Pt cm -2 and 0.8 mg MnO 2 cm -2, it was as high as 10 mA cm -2. Though the current generated on the MnO 2-Pt/C composite electrode in the case of oxygen starvation is not as great as that in the case when oxygen rich, it might be high enough for some cases, such as powering a radio, hearing-aid and so like miniature devices. In an O 2-saturated 1 M H 2SO 4, the presence of MnO 2 in a MnO 2-Pt/C composite electrode primarily plays a catalytic role in the ORR. It enhances the catalytic behavior of Pt for the ORR. The

  12. Li/Ag2VO2PO4 batteries: the roles of composite electrode constituents on electrochemistry

    DOE PAGES

    Bock, David C.; Bruck, Andrea M.; Pelliccione, Christopher J.; ...

    2016-11-01

    In this study, we utilize silver vanadium phosphorous oxide, Ag2VO2PO4, as a model system to systematically study the impact of the constituents of a composite electrode, including polymeric and conductive additives, on electrochemistry. Notably, although highly resistive, this bimetallic cathode can be discharged as a pure electroactive material in the absence of a conductive additive as it generates an in situ conductive matrix via a reduction displacement reaction resulting in the formation of silver metal nanoparticles. Also, three different electrode compositions were investigated: Ag2VO2PO4 only, Ag2VO2PO44 with binder, and Ag2VO2PO4 with binder and carbon. Constant current discharge, pulse testing andmore » impedance spectroscopy measurements were used to characterize the electrochemical properties of the electrodes as a function of depth of discharge. In situ EDXRD was used to spatially resolve the discharge progression within the cathode by following the formation of Ag0. Ex situ XRD and EXAFS modeling were used to quantify the amount of Ag0 formed. Results indicate that the metal center reduced (V5+ or Ag+) was highly dependent on composite composition (presence of PTFE, carbon), depth of discharge (Ag0 nanoparticle formation), and spatial location within the cathode. The addition of a binder was found to increase cell polarization, and the percolation network provided by the carbon in the presence of PTFE was further increased with reduction and formation of Ag0. Lastly, this study provides insight into the factors controlling the electrochemistry of resistive active materials in composite electrodes.« less

  13. Waste Tire Derived Carbon-Polymer Composite Paper as Pseudocapacitive Electrode with Long Cycle Life.

    PubMed

    Boota, M; Paranthaman, M Parans; Naskar, Amit K; Li, Yunchao; Akato, Kokouvi; Gogotsi, Y

    2015-11-01

    Recycling hazardous wastes to produce value-added products is becoming essential for the sustainable progress of our society. Herein, highly porous carbon (1625 m(2)  g(-1)) is synthesized using waste tires as the precursor and used as a supercapacitor electrode material. The narrow pore-size distribution and high surface area led to good charge storage capacity, especially when used as a three-dimensional nanoscaffold to polymerize polyaniline (PANI). The composite paper was highly flexible, conductive, and exhibited a capacitance of 480 F g(-1) at 1 mV s(-1) with excellent capacitance retention of up to 98% after 10,000 charge/discharge cycles. The high capacitance and long cycle life were ascribed to the short diffusional paths, uniform PANI coating, and tight confinement of the PANI in the inner pores of the tire-derived carbon through π-π interactions, which minimized the degradation of the PANI upon cycling. We anticipate that the same strategy can be applied to deposit other pseudocapacitive materials to achieve even higher electrochemical performance and longer cycle life-a key challenge for redox active polymers.

  14. Waste tire derived carbon-polymer composite paper as pseudocapacitive electrode with long cycle life

    SciTech Connect

    Boota, M.; Paranthaman, Mariappan Parans; Naskar, Amit K.; Gogotsi, Yury; Li, Yunchao; Akato, Kokouvi

    2015-09-25

    Recycling hazardous wastes to produce value-added products is becoming essential for the sustainable progress of our society. Herein, highly porous carbon (1625 m2/g–1) is synthesized using waste tires as the precursor and used as supercapacitor electrode. The narrow pore size distribution (PSD) and high surface area led to a good charge storage capacity, especially when used as a three-dimensional nanoscaffold to polymerize polyaniline (PANI/TC). The composite film was highly flexible, conductive and exhibited a capacitance of 480 F/g–1 at 1 mV/s–1 with excellent capacitance retention up to 98% after 10,000 charge/discharge cycles. The high capacitance and long cycle life were ascribed to the short diffusional paths, uniform PANI coating and tight confinement of the PANI in the inner pores of the tire-derived carbon via - interactions, which minimized the degradation of the PANI upon cycling. Here, we anticipate that the same strategy can be applied to deposit other pseudocapacitive materials with low-cost TC to achieve even higher electrochemical performance and longer cycle life, a key challenge for redox active polymers.

  15. Waste tire derived carbon-polymer composite paper as pseudocapacitive electrode with long cycle life

    DOE PAGES

    Boota, M.; Paranthaman, Mariappan Parans; Naskar, Amit K.; ...

    2015-09-25

    Recycling hazardous wastes to produce value-added products is becoming essential for the sustainable progress of our society. Herein, highly porous carbon (1625 m2/g–1) is synthesized using waste tires as the precursor and used as supercapacitor electrode. The narrow pore size distribution (PSD) and high surface area led to a good charge storage capacity, especially when used as a three-dimensional nanoscaffold to polymerize polyaniline (PANI/TC). The composite film was highly flexible, conductive and exhibited a capacitance of 480 F/g–1 at 1 mV/s–1 with excellent capacitance retention up to 98% after 10,000 charge/discharge cycles. The high capacitance and long cycle life weremore » ascribed to the short diffusional paths, uniform PANI coating and tight confinement of the PANI in the inner pores of the tire-derived carbon via - interactions, which minimized the degradation of the PANI upon cycling. Here, we anticipate that the same strategy can be applied to deposit other pseudocapacitive materials with low-cost TC to achieve even higher electrochemical performance and longer cycle life, a key challenge for redox active polymers.« less

  16. Fabrication and Characterization of a Micromachined Swirl-Shaped Ionic Polymer Metal Composite Actuator with Electrodes Exhibiting Asymmetric Resistance

    PubMed Central

    Feng, Guo-Hua; Liu, Kim-Min

    2014-01-01

    This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation. PMID:24824370

  17. Fabrication and characterization of a micromachined swirl-shaped ionic polymer metal composite actuator with electrodes exhibiting asymmetric resistance.

    PubMed

    Feng, Guo-Hua; Liu, Kim-Min

    2014-05-12

    This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation.

  18. Glassy carbon electrode modified with a graphene oxide/poly(o-phenylenediamine) composite for the chemical detection of hydrogen peroxide.

    PubMed

    Nguyen, Van Hoa; Tran, Trung Hieu; Shim, Jae-Jin

    2014-11-01

    Conducting poly(o-phenylenediamine) (POPD)/graphene oxide (GO) composites were prepared using a facile and efficient method involving the in-situ polymerization of OPD in the presence of GO in an aqueous medium. Copper sulfate was used as an oxidative initiator for the polymerization of OPD. Scanning electron microscopy and transmission electron microscopy images showed that POPD microfibrils were formed and distributed relatively uniformly with GO sheets in the obtained composites. X-ray diffraction results revealed the highly crystal structure of POPD. This composite exhibited good catalytic activity and stability. These results highlight the potential applications of POPD/GO composites as excellent electrochemical sensors. The composites were used to modify glass carbon electrodes for the chemical detection of hydrogen peroxide in aqueous media.

  19. Si composite electrode with Li metal doping for advanced lithium-ion battery

    DOEpatents

    Liu, Gao; Xun, Shidi; Battaglia, Vincent

    2015-12-15

    A silicon electrode is described, formed by combining silicon powder, a conductive binder, and SLMP.TM. powder from FMC Corporation to make a hybrid electrode system, useful in lithium-ion batteries. In one embodiment the binder is a conductive polymer such as described in PCT Published Application WO 2010/135248 A1.

  20. Preparation and photoelectrocatalytic performance of N-doped TiO2/NaY zeolite membrane composite electrode material.

    PubMed

    Cheng, Zhi-Lin; Han, Shuai

    2016-01-01

    A novel composite electrode material based on a N-doped TiO2-loaded NaY zeolite membrane (N-doped TiO2/NaY zeolite membrane) for photoelectrocatalysis was presented. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible (UV-vis) and X-ray photoelectron spectroscopy (XPS) characterization techniques were used to analyze the structure of the N-doped TiO2/NaY zeolite membrane. The XRD and SEM results verified that the N-doped TiO2 nanoparticles with the size of ca. 20 nm have been successfully loaded on the porous stainless steel-supported NaY zeolite membrane. The UV-vis result showed that the N-doped TiO2/NaY zeolite membrane exhibited a more obvious red-shift than that of N-TiO2 nanoparticles. The XPS characterization revealed that the doping of N element into TiO2 was successfully achieved. The photoelectrocatalysis performance of the N-doped TiO2/NaY zeolite membrane composite electrode material was evaluated by phenol removal and also the effects of reaction conditions on the catalytic performance were investigated. Owing to exhibiting an excellent catalytic activity and good recycling stability, the N-doped TiO2/NaY zeolite membrane composite electrode material was of promising application for photoelectrocatalysis in wastewater treatment.

  1. Wearable energy-dense and power-dense supercapacitor yarns enabled by scalable graphene–metallic textile composite electrodes

    PubMed Central

    Liu, Libin; Yu, You; Yan, Casey; Li, Kan; Zheng, Zijian

    2015-01-01

    One-dimensional flexible supercapacitor yarns are of considerable interest for future wearable electronics. The bottleneck in this field is how to develop devices of high energy and power density, by using economically viable materials and scalable fabrication technologies. Here we report a hierarchical graphene–metallic textile composite electrode concept to address this challenge. The hierarchical composite electrodes consist of low-cost graphene sheets immobilized on the surface of Ni-coated cotton yarns, which are fabricated by highly scalable electroless deposition of Ni and electrochemical deposition of graphene on commercial cotton yarns. Remarkably, the volumetric energy density and power density of the all solid-state supercapacitor yarn made of one pair of these composite electrodes are 6.1 mWh cm−3 and 1,400 mW cm−3, respectively. In addition, this SC yarn is lightweight, highly flexible, strong, durable in life cycle and bending fatigue tests, and integratable into various wearable electronic devices. PMID:26068809

  2. Binder-free carbon black/stainless steel mesh composite electrode for high-performance anode in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Zheng, Suqi; Yang, Fangfang; Chen, Shuiliang; Liu, Lang; Xiong, Qi; Yu, Ting; Zhao, Feng; Schröder, Uwe; Hou, Haoqing

    2015-06-01

    Carbon black/stainless steel mesh (CB/SSM) composite electrodes were developed as high-performance anodes of microbial fuel cell (MFC) by using a binder-free dipping/drying method. The acid-treatment and thin layer of CB coating greatly improved the microbial adhesion of the electrode surface and facilitated the electron transfer between the bacteria and the electrode surface. As a result, a single-layer CB/SSM anode with thickness of 0.3 mm could generate a projected current density of about 1.53 ± 0.15 mA cm-2 and volumetic current density of 51.0 ± 5.0 mA cm-3, which was much higher than that of the bare SSM anode and conventional carbon felt anode with thickness of 2 mm. Moreover, three-dimensional (3D) CB/SSM electrode could be prepared by simple folding the singe-layer SSM, and produced a projected current density to 10.07 ± 0.88 mA cm-2 and a volumetric current density of 18.66 ± 1.63 mA cm-3. The MFC equipped with the 3D-CB/SSM anode produced a high maximum power density of 3215 ± 80 mW m-2. The CB/SSM electrodes showed good mechanical and electrical properties, excellent microbial adhesion; it represented a high-performance, low-cost electrode material that is easy to fabricate and scale-up.

  3. Template synthesis and characterization of nanostructured lithium insertion electrodes and nanogold/porous aluminum oxide composite membranes

    NASA Astrophysics Data System (ADS)

    Patrissi, Charles John

    A membrane-based template synthesis method was used to prepare nanostructured Li-ion battery electrodes and nanogold/porous aluminum oxide composite membranes. Membrane-based template synthesis is a general method for the preparation of nanomaterials which entails deposition of the material of interest, or a suitable precursor, within the nanometer-diameter pores in a porous template membrane. This method allows for control of nanoparticle size and shape and is compatible with many methods of synthesis for bulk materials. The template membranes used in this work were commercially available porous polycarbonate filtration membranes and nanoporous aluminum oxide membranes that were prepared in-house. Nanostructured electrodes of orthorhombic V2O5, prepared using membrane-based template synthesis, were used to investigate the effects of Li-ion diffusion distance and V2O5 surface area on electrode rate capability. Nanowires of V2O5 were prepared by depositing a precursor in the pores of microporous polycarbonate filtration membranes. The result was an ensemble of 115 nm diameter, 2 mum long nanowires of V2O5 which protruded from a V 2O5 surface layer like the bristles of a brush. The Li + storage capacity of the nanostructured electrode was compared to a thin film control electrode at high discharge rates. Results show that the nanostructured electrode delivered three to four times the capacity of the thin film electrode at discharge rates above 500 C. A membrane based template synthesis method was also used to prepare crystalline V2O5 electrodes which have high volumetric charge capacities, at high discharge rates, compared to a thin-film control electrode. In order to obtain high volumetric rate capability, the as-received polycarbonate template membranes were chemically etched to increase membrane porosity. Nanofibrous electrodes of crystalline V2O5 were then prepared by depositing an alkoxide precursor in the pores of the etched membranes. Electrode volumetric

  4. Layered oxide, graphite and silicon-graphite electrodes for Lithium-ion cells: Effect of electrolyte composition and cycling windows

    SciTech Connect

    Klett, Matilda; Gilbert, James A.; Pupek, Krzysztof Z.; Trask, Stephen E.; Abraham, Daniel P.

    2016-10-14

    The electrochemical performance of cells with a Li1.03(Ni0.5Co0.2Mn0.3)0.97O2 (NCM523) positive electrode and a blended silicon-graphite (Si-Gr) negative electrode are investigated using various electrolyte compositions and voltage cycling windows. Voltage profiles of the blended Si-Gr electrode show a superposition of graphite potential plateaus on a sloped Si profile with a large potential hysteresis. The effect of this hysteresis is seen in the cell impedance versus voltage data, which are distinctly different for the charge and discharge cycles. We confirm that the addition of compounds, such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC) to the baseline 1.2 M LiPF6 in ethylene carbonate (EC): ethyl methyl carbonate (EMC) (3:7 w/w) electrolyte, improves cell capacity retention with higher retention seen at higher additive contents. We show that reducing the lower cutoff voltage (LCV) of full cells to 2.5 V increases the Si-Gr electrode potential to 1.12 V vs. Li/Li+; this relatively-high delithiation potential correlates with the lower capacity retention displayed by the cell. Hence, we show that raising the upper cutoff voltage (UCV) can increase cell energy density without significantly altering capacity retention over 100 charge discharge cycles.

  5. Layered oxide, graphite and silicon-graphite electrodes for Lithium-ion cells: Effect of electrolyte composition and cycling windows

    DOE PAGES

    Klett, Matilda; Gilbert, James A.; Pupek, Krzysztof Z.; ...

    2016-10-14

    The electrochemical performance of cells with a Li1.03(Ni0.5Co0.2Mn0.3)0.97O2 (NCM523) positive electrode and a blended silicon-graphite (Si-Gr) negative electrode are investigated using various electrolyte compositions and voltage cycling windows. Voltage profiles of the blended Si-Gr electrode show a superposition of graphite potential plateaus on a sloped Si profile with a large potential hysteresis. The effect of this hysteresis is seen in the cell impedance versus voltage data, which are distinctly different for the charge and discharge cycles. We confirm that the addition of compounds, such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC) to the baseline 1.2 M LiPF6 in ethylenemore » carbonate (EC): ethyl methyl carbonate (EMC) (3:7 w/w) electrolyte, improves cell capacity retention with higher retention seen at higher additive contents. We show that reducing the lower cutoff voltage (LCV) of full cells to 2.5 V increases the Si-Gr electrode potential to 1.12 V vs. Li/Li+; this relatively-high delithiation potential correlates with the lower capacity retention displayed by the cell. Hence, we show that raising the upper cutoff voltage (UCV) can increase cell energy density without significantly altering capacity retention over 100 charge discharge cycles.« less

  6. Hybrid α-Fe2O3@Ni(OH)2 nanosheet composite for high-rate-performance supercapacitor electrode.

    PubMed

    Jiang, Hong; Ma, Haifeng; Jin, Ying; Wang, Lanfang; Gao, Feng; Lu, Qingyi

    2016-08-24

    In this study, we report a facile fabrication of ultrathin two-dimensional (2D) nanosheet hybrid composite, α-Fe2O3 nanosheet@Ni(OH)2 nanosheet, by a two-step hydrothermal method to achieve high specific capacitance and good stability performance at high charging/discharging rates when serving as electrode material of supercapacitors. The α-Fe2O3@Ni(OH)2 hybrid electrode not only has a smooth decrease of the specific capacitance with increasing current density, compared with the sharp decline of single component of Ni(OH)2 electrode, but also presents excellent rate capability with a specific capacitance of 356 F/g at a current density of 16 A/g and excellent cycling stability (a capacity retention of 93.3% after 500 cycles), which are superior to the performances of Ni(OH)2 with a lower specific capacitance of 132 F/g and a lower capacity retention of 81.8% at 16 A/g. The results indicate such hybrid structure would be promising as excellent electrode material for good performances at high current densities in the future.

  7. Hybrid α-Fe2O3@Ni(OH)2 nanosheet composite for high-rate-performance supercapacitor electrode

    PubMed Central

    Jiang, Hong; Ma, Haifeng; Jin, Ying; Wang, Lanfang; Gao, Feng; Lu, Qingyi

    2016-01-01

    In this study, we report a facile fabrication of ultrathin two-dimensional (2D) nanosheet hybrid composite, α-Fe2O3 nanosheet@Ni(OH)2 nanosheet, by a two-step hydrothermal method to achieve high specific capacitance and good stability performance at high charging/discharging rates when serving as electrode material of supercapacitors. The α-Fe2O3@Ni(OH)2 hybrid electrode not only has a smooth decrease of the specific capacitance with increasing current density, compared with the sharp decline of single component of Ni(OH)2 electrode, but also presents excellent rate capability with a specific capacitance of 356 F/g at a current density of 16 A/g and excellent cycling stability (a capacity retention of 93.3% after 500 cycles), which are superior to the performances of Ni(OH)2 with a lower specific capacitance of 132 F/g and a lower capacity retention of 81.8% at 16 A/g. The results indicate such hybrid structure would be promising as excellent electrode material for good performances at high current densities in the future. PMID:27553663

  8. A novel composite electrode based on tungsten oxide nanoparticles and carbon nanotubes for the electrochemical determination of paracetamol.

    PubMed

    Baytak, Aysegul Kutluay; Duzmen, Sehriban; Teker, Tugce; Aslanoglu, Mehmet

    2015-12-01

    An electrochemical sensor was prepared by the modification of a glassy carbon electrode (GCE) with a composite of nanoparticles of tungsten oxide (WO3) and carbon nanotubes (CNTs) for the quantification of paracetamol (PR). Energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) were performed for the characterization of the nanocomposite layer. Compared with a bare GCE and a GCE modified with CNTs, the proposed electrode (WO3NPs/CNTs/GCE) exhibited a well-defined redox couple for PR and a marked enhancement of the current response. The experimental results also showed that ascorbic acid (AA) did not interfere with the selective determination of PR. The proposed electrode was used for the determination of PR in 0.1M phosphate buffer solution (PBS) at pH7.0 using square wave voltammetry (SWV). The peak current increased linearly with the concentration of PR in the range of 1.0×10(-9)-2.0×10(-7)M. The detection limit (LOD) was 5.54×10(-11)M (based on 3Sb/m). The proposed voltammetric sensor provided long-time stability, improved voltammetric behavior and good reproducibility for PR. The selective, accurate and precise determination of PR makes the proposed electrode of great interest for monitoring its therapeutic use.

  9. Fabrication, characterization of two nano-composite CuO-ZnO working electrodes for dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Habibi, Mohammad Hossein; Karimi, Bahareh; Zendehdel, Mahmoud; Habibi, Mehdi

    2013-12-01

    Two kind of CuO-ZnO nanocomposite working electrodes were synthesized by sol-gel technology and applied in dye-sensitized solar cells (DSSCs). Their characteristics were studied by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and UV-Vis diffuse reflectance spectrum (DRS). CuO-ZnO nanocomposite thin films were prepared doctor blade technique on the fluorine-doped tin oxide (FTO) and used as working electrodes in dye sensitized solar cells (DSSC). Their photovoltaic behavior were compared with standard using D35 dye and an electrolyte containing [Co(bpy)3](PF6)2, [Co(pby)3](PF6)3, LiClO4, and 4-tert-butylpyridine (TBP). The ranges of short-circuit current (JSC) from 0.18 to 0.21 (mA/cm2), open-circuit voltage (VOC) from 0.24 to 0.55 V, and fill factor from 0.34 to 0.39 were obtained for the DSSCs made using the working electrodes. The efficiency of the working electrodes after the addition of TBL was more than doubled. The light scattering and carrier transport properties of these composites promote the performance of dye-sensitized solar cells (DSSCs).

  10. Nanocellulose coupled flexible polypyrrole@graphene oxide composite paper electrodes with high volumetric capacitance

    NASA Astrophysics Data System (ADS)

    Wang, Zhaohui; Tammela, Petter; Strømme, Maria; Nyholm, Leif

    2015-02-01

    A robust and compact freestanding conducting polymer-based electrode material based on nanocellulose coupled polypyrrole@graphene oxide paper is straightforwardly prepared via in situ polymerization for use in high-performance paper-based charge storage devices, exhibiting stable cycling over 16 000 cycles at 5 A g-1 as well as the largest specific volumetric capacitance (198 F cm-3) so far reported for flexible polymer-based electrodes.A robust and compact freestanding conducting polymer-based electrode material based on nanocellulose coupled polypyrrole@graphene oxide paper is straightforwardly prepared via in situ polymerization for use in high-performance paper-based charge storage devices, exhibiting stable cycling over 16 000 cycles at 5 A g-1 as well as the largest specific volumetric capacitance (198 F cm-3) so far reported for flexible polymer-based electrodes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07251k

  11. Electron Beam Curing of Composite Positive Electrode for Li-Ion Battery

    DOE PAGES

    Du, Zhijia; Janke, C. J.; Li, Jianlin; ...

    2016-10-12

    We have successfully used electron beam cured acrylated polyurethanes as novel binders for positive electrodes for Li-ion batteries. Furthermore, the cross-linked polymer after electron beam curing coheres active materials and carbon black together onto Al foil. Electrochemical tests demonstrate the stability of the polymer at a potential window of 2.0 V–4.6 V. The electrode is found to have similar voltage profiles and charge-transfer resistance compared to the conventional electrode using polyvinylidene fluoride as the binder. Finally, when the electrode is tested in full Li-ion cells, they exhibit excellent cycling performance, indicating promising use for this new type of binder inmore » commercial Li-ion batteries in the future.« less

  12. Electron Beam Curing of Composite Positive Electrode for Li-Ion Battery

    SciTech Connect

    Du, Zhijia; Janke, C. J.; Li, Jianlin; Daniel, C.; Wood, D. L.

    2016-10-12

    We have successfully used electron beam cured acrylated polyurethanes as novel binders for positive electrodes for Li-ion batteries. Furthermore, the cross-linked polymer after electron beam curing coheres active materials and carbon black together onto Al foil. Electrochemical tests demonstrate the stability of the polymer at a potential window of 2.0 V–4.6 V. The electrode is found to have similar voltage profiles and charge-transfer resistance compared to the conventional electrode using polyvinylidene fluoride as the binder. Finally, when the electrode is tested in full Li-ion cells, they exhibit excellent cycling performance, indicating promising use for this new type of binder in commercial Li-ion batteries in the future.

  13. Determination of salidroside and tyrosol in Rhodiola by capillary electrophoresis with graphene/poly(urea-formaldehyde) composite modified electrode.

    PubMed

    Chen, Bo; Zhang, Luyan; Chen, Gang

    2011-04-01

    This report describes the fabrication and application of a novel graphene/poly(urea-formaldehyde) composite modified electrode as a sensitive amperometric detector of CE. The composite electrode was fabricated on the basis of the in situ polycondensation of a mixture of graphenes and urea-formaldehyde prepolymers on the surface of a platinum disc electrode. It was coupled with CE for the separation and detection of salidroside and tyrosol in Rhodiola, a traditional Chinese medicine, to demonstrate its feasibility and performance. Salidroside and tyrosol have been well separated within 6 min in a 40 cm long capillary at a separation voltage of 12 kV using a 50 mM borate buffer (pH 9.8). The prepared graphene-based CE detector offered significantly lower detection potential, yielded enhanced signal-to-noise characteristics, and exhibited high resistance to surface fouling and enhanced stability. It showed long-term stability and reproducibility with relative standard deviations of less than 5% for the peak current (n = 15).

  14. Covalently functionalized single-walled carbon nanotubes and graphene composite electrodes for pseudocapacitor application

    NASA Astrophysics Data System (ADS)

    Le Barny, Pierre; Servet, Bernard; Campidelli, Stéphane; Bondavalli, Paolo; Galindo, Christophe

    2013-09-01

    The use of carbon-based materials in electrochemical double-layer supercapacitors (EDLC) is currently being the focus of much research. Even though activated carbon (AC) is the state of the art electrode material, AC suffers from some drawbacks including its limited electrical conductivity, the need for a binder to ensure the expected electrode cohesion and its limited accessibility of its pores to solvated ions of the electrolyte. Owing to their unique physical properties, carbon nanotubes (CNTs) or graphene could overcome these drawbacks. It has been demonstrated that high specific capacitance could be obtained when the carbon accessible surface area of the electrode was finely tailored by using graphene combined with other carbonaceous nanoparticles such as CNTs12.In this work, to further increase the specific capacitance of the electrode, we have covalently grafted onto the surface of single-walled carbon nanotubes (SWCNTs), exfoliated graphite or graphene oxide (GO), anthraquinone (AQ) derivatives which are electrochemically active materials. The modified SWCNTs and graphene-like materials have been characterized by Raman spectroscopy, X-ray photoemission and cyclic voltammetry . Then suspensions based on mixtures of modified SWCNTs and modified graphene-like materials have been prepared and transformed into electrodes either by spray coating or by filtration. These electrodes have been characterized by SEM and by cyclic voltammetry in 0.1M H2S04 electrolyte.

  15. Constructing 3D branched nanowire coated macroporous metal oxide electrodes with homogeneous or heterogeneous compositions for efficient solar cells.

    PubMed

    Wu, Wu-Qiang; Xu, Yang-Fan; Rao, Hua-Shang; Feng, Hao-Lin; Su, Cheng-Yong; Kuang, Dai-Bin

    2014-05-05

    Light-harvesting and charge collection have attracted increasing attention in the domain of photovoltaic cells, and can be facilitated dramatically by appropriate design of a photonic nanostructure. However, the applicability of current light-harvesting photoanode materials with single component and/or morphology (such as, particles, spheres, wires, sheets) is still limited by drawbacks such as insufficient electron-hole separation and/or light-trapping. Herein, we introduce a universal method to prepare hierarchical assembly of macroporous material-nanowire coated homogenous or heterogeneous metal oxide composite electrodes (TiO2 -TiO2 , SnO2 -TiO2 , and Zn2 SnO4 -TiO2 ; homogenous refers to a material in which the nanowire and the macroporous material have the same composition, i.e. both are TiO2 . Heterogeneous refers to a material in which the nanowires and the macroporous material have different compositions). The dye-sensitized solar cell based on a TiO2 -macroporous material-TiO2 -nanowire homogenous composition electrode shows an impressive conversion efficiency of 9.51 %, which is much higher than that of pure macroporous material-based photoelectrodes to date.

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

    PubMed

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

    2013-02-07

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

  17. Freestanding nanocellulose-composite fibre reinforced 3D polypyrrole electrodes for energy storage applications

    NASA Astrophysics Data System (ADS)

    Wang, Zhaohui; Tammela, Petter; Zhang, Peng; Huo, Jinxing; Ericson, Fredric; Strømme, Maria; Nyholm, Leif

    2014-10-01

    It is demonstrated that 3D nanostructured polypyrrole (3D PPy) nanocomposites can be reinforced with PPy covered nanocellulose (PPy@nanocellulose) fibres to yield freestanding, mechanically strong and porosity optimised electrodes with large surface areas. Such PPy@nanocellulose reinforced 3D PPy materials can be employed as free-standing paper-like electrodes in symmetric energy storage devices exhibiting cell capacitances of 46 F g-1, corresponding to specific electrode capacitances of up to ~185 F g-1 based on the weight of the electrode, and 5.5 F cm-2 at a current density of 2 mA cm-2. After 3000 charge/discharge cycles at 30 mA cm-2, the reinforced 3D PPy electrode material also showed a cell capacitance corresponding to 92% of that initially obtained. The present findings open up new possibilities for the fabrication of high performance, low-cost and environmentally friendly energy-storage devices based on nanostructured paper-like materials.It is demonstrated that 3D nanostructured polypyrrole (3D PPy) nanocomposites can be reinforced with PPy covered nanocellulose (PPy@nanocellulose) fibres to yield freestanding, mechanically strong and porosity optimised electrodes with large surface areas. Such PPy@nanocellulose reinforced 3D PPy materials can be employed as free-standing paper-like electrodes in symmetric energy storage devices exhibiting cell capacitances of 46 F g-1, corresponding to specific electrode capacitances of up to ~185 F g-1 based on the weight of the electrode, and 5.5 F cm-2 at a current density of 2 mA cm-2. After 3000 charge/discharge cycles at 30 mA cm-2, the reinforced 3D PPy electrode material also showed a cell capacitance corresponding to 92% of that initially obtained. The present findings open up new possibilities for the fabrication of high performance, low-cost and environmentally friendly energy-storage devices based on nanostructured paper-like materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c

  18. Electrochemical luminescence determination of hyperin using a sol-gel@graphene luminescent composite film modified electrode for solid phase microextraction

    NASA Astrophysics Data System (ADS)

    Zou, Xiaojun; Shang, Fang; Wang, Sui

    2017-02-01

    In this paper, a novel electrochemiluminescence (ECL) sensor of sol-gel@graphene luminescent composite film modified electrode for hyperin determination was prepared using graphene (G) as solid-phase microextraction (SPME) material, based on selective preconcentration of target onto an electrode and followed by luminol ECL detection. Hyperin was firstly extracted from aqueous solution through the modified GCE. Hydrogel, electrogenerated chemiluminescence reagents, pH of working solution, extraction time and temperature and scan rate were discussed. Under the optimum conditions, the change of ECL intensity was in proportion to the concentration of hyperin in the range of 0.02-0.24 μg/mL with a detection limit of 0.01 μg/mL. This method showed good performance in stability, reproducibility and precision for the determination of hyperin.

  19. Binderless Composite Electrode Monolith from Carbon Nanotube and Biomass Carbon Activated by KOH and CO2 Gas for Supercapacitor

    NASA Astrophysics Data System (ADS)

    Farma, R.; Deraman, M.; Omar, R.; Awitdrus, Ishak, M. M.; Taer, E.; Talib, I. A.

    2011-12-01

    This paper presents a method to improve the performance of supercapacitors fabricated using binderless composite electrode monolith (BCMs) from self-adhesive carbon grains (SACG) of fibers from oil palm empty fruit bunches. The BCMs were prepared from green monoliths (GMs) contain SACG, SACG treated with KOH (5 % by weight) and SACG mixed with carbon nanotubes (CNTs) (5% by weight) and KOH (5 % by weight), respectively. These GMs were carbonized at 800 ° C under N2 environment and activated by CO2 gas at 800 ° C for 1 hour. It was found that addition of KOH and CNTs produced BCMs with higher specific capacitance and smaller internal resistance, respectively. It was also found that supercapacitor cells using these BCMs as electrodes exhibited a better specific energy and specific power. The physical properties of BCMs (density, electrical conductivity, porosity, interlayer spacing, crystallite dimension and microstructure) were affected by the addition of KOH and CNTs.

  20. Electrochemical Properties of Poly(Anthraquinonyl Sulfide)/Graphene Sheets Composites as Electrode Materials for Electrochemical Capacitors

    PubMed Central

    Lee, Wonkyun; Suzuki, Shinya; Miyayama, Masaru

    2014-01-01

    Poly(anthraquinonyl sulfide) (PAQS)/graphene sheets (GSs) composite was synthesized through in situ polymerization to evaluate its performance as an electrode material for electrochemical capacitors. PAQS was successfully synthesized in the presence of GSs with uniform distribution. PAQS/GSs showed a pair of reversible redox peaks at around 0 V (vs. Ag/AgCl). The specific capacitance of PAQS/GSs was 349 F·g−1 (86 mAh·g−1) at a current density of 500 mA·g−1, and a capacitance of 305 F·g−1 was maintained even at a high current density of 5000 mA·g−1. The in situ polymerization of PAQS with GSs facilitated their interaction and enabled faster charge transfer and redox reaction, resulting in enhanced electrode properties.

  1. Electrochemical Properties of Poly(Anthraquinonyl Sulfide)/Graphene Sheets Composites as Electrode Materials for Electrochemical Capacitors.

    PubMed

    Lee, Wonkyun; Suzuki, Shinya; Miyayama, Masaru

    2014-07-30

    Poly(anthraquinonyl sulfide) (PAQS)/graphene sheets (GSs) composite was synthesized through in situ polymerization to evaluate its performance as an electrode material for electrochemical capacitors. PAQS was successfully synthesized in the presence of GSs with uniform distribution. PAQS/GSs showed a pair of reversible redox peaks at around 0 V (vs. Ag/AgCl). The specific capacitance of PAQS/GSs was 349 F·g(-1) (86 mAh·g(-1)) at a current density of 500 mA·g(-1), and a capacitance of 305 F·g(-1) was maintained even at a high current density of 5000 mA·g(-1). The in situ polymerization of PAQS with GSs facilitated their interaction and enabled faster charge transfer and redox reaction, resulting in enhanced electrode properties.

  2. Performance of polymer nano composite membrane electrode assembly using Alginate as a dopant in polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Mulijani, S.

    2016-11-01

    Polymer membrane and composite polymer for membrane electrode assembly (MEAs) are synthesized and studied for usage in direct methanol fuel cell (DMFC). In this study, we prepared 3 type of MEAs, polystyrene (PS), sulfonated polystyrene (SPS) and composite polymer SPS-alginat membrane via catalyst hot pressed method. The performance and properties of prepared MEAs were evaluated and analyzed by impedance spectrometry and scanning electron microscopy (SEM). The result showed that, water up take of MEA composite polymer SPS-alginate was obtained higher than that in SPS and PS. The proton conductivity of MEA-SPS-alginate was also higher than that PS and PSS. SEM characterization revealed that the intimate contact between the carbon catalyst layers (CL) and the membranes, and the uniformly porous structure correlate positively with the MEAs prepared by hot pressed method, exhibiting high performances for DMFC.

  3. Performance of polymer nano composite membrane electrode assembly using Alginate as a dopant in polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Mulijani, S.

    2017-01-01

    Polymer membrane and composite polymer for membrane electrode assembly (MEAs) are synthesized and studied for usage in direct methanol fuel cell (DMFC). In this study, we prepared 3 type of MEAs, polystyrene (PS), sulfonated polystyrene (SPS) and composite polymer SPS-alginat membrane via catalyst hot pressed method. The performance and properties of prepared MEAs were evaluated and analyzed by impedance spectrometry and scanning electron microscopy (SEM). The result showed that, water up take of MEA composite polymer SPS-alginate was obtained higher than that in SPS and PS. The proton conductivity of MEA-SPS-alginate was also higher than that PS and PSS. SEM characterization revealed that the intimate contact between the carbon catalyst layers (CL) and the membranes, and the uniformly porous structure correlate positively with the MEAs prepared by hot pressed method, exhibiting high performances for DMFC.

  4. Nickel cobalt oxide nanowire-reduced graphite oxide composite material and its application for high performance supercapacitor electrode material.

    PubMed

    Wang, Xu; Yan, Chaoyi; Sumboja, Afriyanti; Lee, Pooi See

    2014-09-01

    In this paper, we report a facile synthesis method of mesoporous nickel cobalt oxide (NiCo2O4) nanowire-reduced graphite oxide (rGO) composite material by urea induced hydrolysis reaction, followed by sintering at 300 degrees C. P123 was used to stabilize the GO during synthesis, which resulted in a uniform coating of NiCo2O4 nanowire on rGO sheet. The growth mechanism of the composite material is discussed in detail. The NiCo2O4-rGO composite material showed an outstanding electrochemical performance of 873 F g(-1) at 0.5 A g(-1) and 512 F g(-1) at 40 A g(-1). This method provides a promising approach towards low cost and large scale production of supercapacitor electrode material.

  5. Synergistic effect of carbon nanofiber/nanotube composite catalyst on carbon felt electrode for high-performance all-vanadium redox flow battery.

    PubMed

    Park, Minjoon; Jung, Yang-jae; Kim, Jungyun; Lee, Ho il; Cho, Jeaphil

    2013-10-09

    Carbon nanofiber/nanotube (CNF/CNT) composite catalysts grown on carbon felt (CF), prepared from a simple way involving the thermal decomposition of acetylene gas over Ni catalysts, are studied as electrode materials in a vanadium redox flow battery. The electrode with the composite catalyst prepared at 700 °C (denoted as CNF/CNT-700) demonstrates the best electrocatalytic properties toward the V(2+)/V(3+) and VO(2+)/VO2(+) redox couples among the samples prepared at 500, 600, 700, and 800 °C. Moreover, this composite electrode in the full cell exhibits substantially improved discharge capacity and energy efficiency by ~64% and by ~25% at 40 mA·cm(-2) and 100 mA·cm(-2), respectively, compared to untreated CF electrode. This outstanding performance is due to the enhanced surface defect sites of exposed edge plane in CNF and a fast electron transfer rate of in-plane side wall of the CNT.

  6. Silicon oxycarbide glass-graphene composite paper electrode for long-cycle lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    David, Lamuel; Bhandavat, Romil; Barrera, Uriel; Singh, Gurpreet

    2016-03-01

    Silicon and graphene are promising anode materials for lithium-ion batteries because of their high theoretical capacity; however, low volumetric energy density, poor efficiency and instability in high loading electrodes limit their practical application. Here we report a large area (approximately 15 cm × 2.5 cm) self-standing anode material consisting of molecular precursor-derived silicon oxycarbide glass particles embedded in a chemically-modified reduced graphene oxide matrix. The porous reduced graphene oxide matrix serves as an effective electron conductor and current collector with a stable mechanical structure, and the amorphous silicon oxycarbide particles cycle lithium-ions with high Coulombic efficiency. The paper electrode (mass loading of 2 mg cm-2) delivers a charge capacity of ~588 mAh g-1electrode (~393 mAh cm-3electrode) at 1,020th cycle and shows no evidence of mechanical failure. Elimination of inactive ingredients such as metal current collector and polymeric binder reduces the total electrode weight and may provide the means to produce efficient lightweight batteries.

  7. Silicon oxycarbide glass-graphene composite paper electrode for long-cycle lithium-ion batteries

    PubMed Central

    David, Lamuel; Bhandavat, Romil; Barrera, Uriel; Singh, Gurpreet

    2016-01-01

    Silicon and graphene are promising anode materials for lithium-ion batteries because of their high theoretical capacity; however, low volumetric energy density, poor efficiency and instability in high loading electrodes limit their practical application. Here we report a large area (approximately 15 cm × 2.5 cm) self-standing anode material consisting of molecular precursor-derived silicon oxycarbide glass particles embedded in a chemically-modified reduced graphene oxide matrix. The porous reduced graphene oxide matrix serves as an effective electron conductor and current collector with a stable mechanical structure, and the amorphous silicon oxycarbide particles cycle lithium-ions with high Coulombic efficiency. The paper electrode (mass loading of 2 mg cm−2) delivers a charge capacity of ∼588 mAh g−1electrode (∼393 mAh cm−3electrode) at 1,020th cycle and shows no evidence of mechanical failure. Elimination of inactive ingredients such as metal current collector and polymeric binder reduces the total electrode weight and may provide the means to produce efficient lightweight batteries. PMID:27025781

  8. Freestanding nanocellulose-composite fibre reinforced 3D polypyrrole electrodes for energy storage applications.

    PubMed

    Wang, Zhaohui; Tammela, Petter; Zhang, Peng; Huo, Jinxing; Ericson, Fredric; Strømme, Maria; Nyholm, Leif

    2014-11-07

    It is demonstrated that 3D nanostructured polypyrrole (3D PPy) nanocomposites can be reinforced with PPy covered nanocellulose (PPy@nanocellulose) fibres to yield freestanding, mechanically strong and porosity optimised electrodes with large surface areas. Such PPy@nanocellulose reinforced 3D PPy materials can be employed as free-standing paper-like electrodes in symmetric energy storage devices exhibiting cell capacitances of 46 F g(-1), corresponding to specific electrode capacitances of up to ∼185 F g(-1) based on the weight of the electrode, and 5.5 F cm(-2) at a current density of 2 mA cm(-2). After 3000 charge/discharge cycles at 30 mA cm(-2), the reinforced 3D PPy electrode material also showed a cell capacitance corresponding to 92% of that initially obtained. The present findings open up new possibilities for the fabrication of high performance, low-cost and environmentally friendly energy-storage devices based on nanostructured paper-like materials.

  9. High Energy Density Asymmetric Supercapacitor Based on NiOOH/Ni3S2/3D Graphene and Fe3O4/Graphene Composite Electrodes

    PubMed Central

    Lin, Tsung-Wu; Dai, Chao-Shuan; Hung, Kuan-Chung

    2014-01-01

    The application of the composite of Ni3S2 nanoparticles and 3D graphene as a novel cathode material for supercapacitors is systematically investigated in this study. It is found that the electrode capacitance increases by up to 111% after the composite electrode is activated by the consecutive cyclic voltammetry scanning in 1 M KOH. Due to the synergistic effect, the capacitance and the diffusion coefficient of electrolyte ions of the activated composite electrode are ca. 3.7 and 6.5 times higher than those of the Ni3S2 electrode, respectively. Furthermore, the activated composite electrode exhibits an ultrahigh specific capacitance of 3296 F/g and great cycling stability at a current density of 16 A/g. To obtain the reasonable matching of cathode/anode electrodes, the composite of Fe3O4 nanoparticles and chemically reduced graphene oxide (Fe3O4/rGO) is synthesized as the anode material. The Fe3O4/rGO electrode exhibits the specific capacitance of 661 F/g at 1 A/g and excellent rate capability. More importantly, an asymmetric supercapacitor fabricated by two different composite electrodes can be operated reversibly between 0 and 1.6 V and obtain a high specific capacitance of 233 F/g at 5 mV/s, which delivers a maximum energy density of 82.5 Wh/kg at a power density of 930 W/kg. PMID:25449978

  10. Integral planar supercapacitor with CNT-based composite electrodes for heat-sensitive MEMS and NEMS

    NASA Astrophysics Data System (ADS)

    Lebedev, E.; Alekseyev, A.; Gavrilin, I.; Sysa, A.; Kitsyuk, E.; Ryazanov, R.; Gromov, D.

    2016-12-01

    A method based on electrophoretic deposition (EPD) has been developed to produce uniform and local deposits of multiwalled carbon nanotubes (CNT) on interdigital structures of planar supercapacitor (SC) at room temperatures. Alcohol/acetone suspensions were used under constant voltage conditions in the range of 6 to 100 V, with deposition times ranging from 2 to 60 minutes and electrodes space from 2 to 15 mm. It was shown that for dense layers deposition with good adhesion on the narrow lines of the planar SC electrodes it is necessary to use average values of the electric field and multi-stage method in which the deposition and drying processes are alternated. Electrochemical tests of the sandwich-like supercapacitors with electrodes obtained by the described method were carried out. The specific capacity of experimental samples increased from 0.24 to 1.07 mF/cm2 with an increase in the number of EPD cycles from 3 to 9.

  11. The ternary MnFe2O4/graphene/polyaniline hybrid composite as negative electrode for supercapacitors

    NASA Astrophysics Data System (ADS)

    Sankar, Kalimuthu Vijaya; Selvan, Ramakrishnan Kalai

    2015-02-01

    The ternary MnFe2O4/graphene/polyaniline (PANI) composite was successfully prepared for the negative electrode in hybrid supercapacitors. The MnFe2O4 particles are synthesized by polymer assisted solution combustion method without any high temperature calcinations. Similarly, the flexible graphene and PANI are prepared by eco-friendly hydrothermal and in situ polymerization method, respectively. The presence of possible functional groups and the existence of individual constituents in the composite were identified through Fourier transform infra-red spectra (FT-IR) and Raman spectra. Transmission electron microscope (TEM) image reveals that the MnFe2O4 particles are dispersed on the flexible graphene sheet and are wrapped by PANI. The ternary composite electrode delivered a specific capacitance of 241 F g-1 at 0.5 mA cm-2, which was 7.5 times higher than MnFe2O4. The calculated b-value elucidates that the charge storage mechanism in the ternary system is based on the capacitive behavior rather than intercalation. The increase in ratio between capacitive and intercalation current with respect to scan rate corroborates that the pseudocapacitive charge storage mechanism is dominant. Further, the fabricated hybrid supercapacitor provides the maximum specific capacitance and energy density of 48.5 F g-1 at 0.5 mA cm-2 and 17 Wh kg-1, respectively. In addition, the hybrid supercapacitor exhibits excellent cyclic stability of up to 5000 successive cycles.

  12. Enzymatic fuel cells based on electrodeposited graphite oxide/cobalt hydroxide/chitosan composite-enzyme electrode.

    PubMed

    Uk Lee, Hee; Young Yoo, Hah; Lkhagvasuren, Tseveg; Seok Song, Yoon; Park, Chulhwan; Kim, Jungbae; Wook Kim, Seung

    2013-04-15

    Enzymatic fuel cells (EFCs) use redox enzymes with high electron transfer rates that lead to high power density from bioavailable substrates. However, EFCs are limited by the difficult electrical wiring of the enzymes to the electrode. Therefore, deposition of Co(OH)₂ onto graphite oxide (GO) was improved for efficient wiring of the enzymes. The GO/Co(OH)₂/chitosan composites were electrodeposited for immobilization of glucose oxidase (GOD) or laccase on an Au electrode, respectively. The electrical properties of the bioelectrode according to cyclic voltammetry were improved using GO/Co(OH)₂/chitosan composites. The anode and cathode system was composed of GOD and laccase as biocatalysts and glucose/oxygen as substrates under ambient conditions (pH 7.0 and 25 °C). The EFC using GO/Co(OH)₂/chitosan composites with a mediator delivered a high power density of up to 517±3.3 μW/cm² at 0.46 V and open circuit voltage of 0.60 V. These results provide a promising direction for further development and application of EFCs.

  13. Facile construction of 3D graphene/MoS2 composites as advanced electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Sun, Tianhua; Li, Zhangpeng; Liu, Xiaohong; Ma, Limin; Wang, Jinqing; Yang, Shengrong

    2016-11-01

    Flower-like molybdenum disulfide (MoS2) microstructures are synthesized based on three-dimensional graphene (3DG) skeleton via a simple and facile one-step hydrothermal method, aiming at constructing series of novel composite electrode materials of 3DG/MoS2 with high electrochemical performances for supercapacitors. The electrochemical properties of the samples are evaluated by cyclic voltammetry and galvanostatic charge/discharge tests. Specifically, the optimal 3DG/MoS2 composite exhibits remarkable performances with a high specific capacitance of 410 F g-1 at a current density of 1 A g-1 and an excellent cycling stability with ca. 80.3% capacitance retention after 10,000 continuous charge-discharge cycles at a high current density of 2 A g-1, making it adaptive for high-performance supercapacitors. The enhanced electrochemical performances can be ascribed to the combination of 3DG and flower-like MoS2, which provides excellent charge transfer network and electrolyte diffusion channels while effectively prevents the collapse, aggregation and morphology change of active materials during charge-discharge process. The results demonstrate that 3DG/MoS2 composite is one of the attractive electrode materials for supercapacitors.

  14. Electrochemical degradation of carbamazepine using modified electrode with graphene-AuAg composite

    NASA Astrophysics Data System (ADS)

    Pogacean, F.; Biris, A. R.; Socaci, C.; Floare-Avram, V.; Rosu, M. C.; Coros, M.; Pruneanu, S.

    2015-12-01

    Carbamazepine is a pharmaceutical drug which has been detected in surface and drinking water primarily due to human usage but also from the accidental disposal of pharmaceuticals into sewers. We have developed a graphene-modified electrode which was tested at the detection and degradation of carbamazepine. The oxidation process was studied by cyclic voltammetry in aqueous and organic solutions. The electrochemical degradation of carbamazepine was performed by polarizing the working electrode at a certain potential, for different times (from 5 to 60 minutes). The degradation efficiency was highly dependent on the type of solution and on the supporting electrolyte.

  15. Chemically and compositionally modified solid solution disordered multiphase nickel hydroxide positive electrode for alkaline rechargeable electrochemical cells

    DOEpatents

    Ovshinsky, Stanford R.; Corrigan, Dennis; Venkatesan, Srini; Young, Rosa; Fierro, Christian; Fetcenko, Michael A.

    1994-01-01

    A high capacity, long cycle life positive electrode for use in an alkaline rechargeable electrochemical cell comprising: a solid solution nickel hydroxide material having a multiphase structure that comprises at least one polycrystalline .gamma.-phase including a polycrystalline .gamma.-phase unit cell comprising spacedly disposed plates with at least one chemical modifier incorporated around the plates, the plates having a range of stable intersheet distances corresponding to a 2.sup.+ oxidation state and a 3.5.sup.+, or greater, oxidation state; and at least one compositional modifier incorporated into the solid solution nickel hydroxide material to promote the multiphase structure.

  16. Creation of additional electrical pathways for the robust stretchable electrode by using UV irradiated CNT-elastomer composite

    NASA Astrophysics Data System (ADS)

    Lee, So-Young; Hyun, Seungmin; Jang, Bongkyun; Kim, Sangmin; Kim, Myoungho; Lee, Hoo-Jeong; Weon, Byung Mook; Shim, Hyung Cheoul

    2016-10-01

    In this study, we fabricate an electrode structure, in which a carbon nanotube (CNT) film is coated on the composite of carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS). Electromechanical tests disclose that incorporation of a high density of well-dispersed CNTs (with the aid of UV/O3 treatment) in the PDMS substrate offers an alternative current path when the CNT film cracked, helping demonstrate much improved electromechanical characteristics. Further analysis using scanning electron microscopy (SEM) combined with the data from the electromechanical tests illuminates some interesting electromechanical features and the failure mechanism of the material.

  17. (Metal-Organic Framework)-Polyaniline sandwich structure composites as novel hybrid electrode materials for high-performance supercapacitor

    NASA Astrophysics Data System (ADS)

    Guo, ShuaiNan; Zhu, Yong; Yan, YunYun; Min, YuLin; Fan, JinChen; Xu, QunJie; Yun, Hong

    2016-06-01

    Carbonized Zn-(Metal-Organic Framework)MOF- polyaniline composites for high performance of supercapacitor have been developed from zinc acetate, 8-Hydroxyquinoline, and aniline via a simple process. The as-synthesized product has been characterized by X-ray powder diffraction (XRD), Scanning electron microscopy(SEM), Fourier transform infrared spectra (FT-IR), Transmission electron microscope (TEM). The electrochemical properties of carbonized Zn-MOF/polyaniline electrode were investigated by current charge-discharge and cyclic voltammetry. The specific capacitance of MOF/PANI has been approach to be as high as 477 F g-1 at a current density of 1 A g-1.

  18. Atomic and Molecular Layer Deposition for Enhanced Lithium Ion Battery Electrodes and Development of Conductive Metal Oxide/Carbon Composites

    NASA Astrophysics Data System (ADS)

    Travis, Jonathan

    The performance and safety of lithium-ion batteries (LIBs) are dependent on interfacial processes at the positive and negative electrodes. For example, the surface layers that form on cathodes and anodes are known to affect the kinetics and capacity of LIBs. Interfacial reactions between the electrolyte and the electrodes are also known to initiate electrolyte combustion during thermal runaway events that compromise battery safety. Atomic layer deposition (ALD) and molecular layer deposition (MLD) are thin film deposition techniques based on sequential, self-limiting surface reactions. ALD and MLD can deposit ultrathin and conformal films on high aspect ratio and porous substrates such as composite particulate electrodes in lithium-ion batteries. The effects of electrode surface modification via ALD and MLD are studied using a variety of techniques. It was found that sub-nm thick coatings of Al2O 3 deposited via ALD have beneficial effects on the stability of LIB anodes and cathodes. These same Al2O3 ALD films were found to improve the safety of graphite based anodes through prevention of exothermic solid electrolyte interface (SEI) degradation at elevated temperatures. Ultrathin and conformal metal alkoxide polymer films known as "metalcones" were grown utilizing MLD techniques with trimethylaluminum (TMA) or titanium tetrachloride (TiCl4) and organic diols or triols, such as ethylene glycol (EG), glycerol (GL) or hydroquinone (HQ), as the reactants. Pyrolysis of these metalcone films under inert gas conditions led to the development of conductive metal oxide/carbon composites. The composites were found to contain sp2 carbon using micro-Raman spectroscopy in the pyrolyzed films with pyrolysis temperatures ≥ 600°C. Four point probe measurements demonstrated that the graphitic sp2 carbon domains in the metalcone films grown using GL and HQ led to significant conductivity. The pyrolysis of conformal MLD films to obtain conductive metal oxide/carbon composite films

  19. Electrochemical identification of metal ions in archaeological ceramic glazes by stripping voltammetry at graphite/polyester composite electrodes.

    PubMed

    Doménech-Carbó, A; Doménech-Carbó, M T; Osete-Cortina, L; Gimeno-Adelantado, J V; Bosch-Reig, F; Mateo-Castro, R

    2002-01-04

    The electrochemical response of metal ions in different samples of coloured ceramic tin-lead glazes attached to graphite/polyester composite electrodes is described. In addition to the ubiquous signals for lead, reductive dissolution processes are followed by anodic stripping peaks for Co, Cu, Sb, Mn, Sn and Fe, enabling the direct identification of such elements in microsamples proceeding from archaeological glazed tiles from Valencia (Spain) workshops (16th-18th century). Additional anodic and cathodic peaks corresponding to redox processes involving metal species in solution generated during stripping processes are also used. Peak potentials, Tafel plots and shape parameters are used for characterising the different species.

  20. A novel urea amperometric biosensor based on secretion of carnation petal cells modified on a graphite-epoxy composite electrode.

    PubMed

    Pang, Chunyan; Zhu, Yongchun; Gao, Hongyan; Dong, Yue; Lu, Jie

    2011-02-21

    A new kind of biosensor for the detection of urea with a high selectivity, sensitivity and wide detection range was designed based on the secretion of carnation petals cells paste covered over a graphite-epoxy composite basic electrode surface. The carnation petal paste from mashed fresh carnation petals was tightly fixed on the basic electrode surface with Teflon thin film to keep it in contact with the electrode surface. Urea in aqueous solution was detected by differential pulse voltammetry based on the oxidation peak current at 0.316 V (vs. SCE) of the secreted species of carnation petal cells during the mashing process, which interacts with urea molecules and results in the decrease of the oxidation peak current. The oxidation peak current decreases linearly with the logarithm of urea concentration in the range of 1.3 × 10(-16)-4.57 × 10(-8) M and 3.4 × 10(-7)-1.3 × 10(-1) M with a detection limit of 7.5 × 10(-16) M. The biosensor was characterized by electrochemistry and fluorescent spectrometry, and applied to the determination of urea in waste water from a river around Shenyang Normal University campus with a recovery of 104.5% (RSD is 5.00%). The presence of larger amounts of ammonium ion and nitrate ion up to the molar ratio of 10(4) do not interfere with the urea detection.

  1. The Development of Nano-Composite Electrodes for Solid Oxide Electrolyzers

    SciTech Connect

    Gorte, Raymond J.; Vohs, John M.

    2014-03-26

    Solid oxide fuel cells (SOFC) and electrolyzers (SOE) offer an attractive means for converting between electrical and chemical energy. Because they operate at high temperatures and are usually based on electrolytes that are oxygen-ion conducting ceramics, such as yttria-stabilized zirconia (YSZ), they are equally capable of converting between CO and CO2 as between H2 and H2O. When operated in the SOFC mode, they are able to operate on hydrocarbon fuels so long as there are no materials within the anode that can catalyze carbon formation. Compared to other types of electrolyzers, SOE can exhibit the highest efficiencies because the theoretical Nernst potential is lower at high temperatures and because the electrode overpotentials in SOE tend to be much lower. Finally, pure H2 can be produced without an external electrical source by electrolysis of steam at one electrode and oxidation of any fuel at the other electrode through a process known as Natural-Gas Assisted Steam Electrolysis. This final report describes results from studies of novel electrodes for SOE and SOFC prepared by infiltration methods.

  2. Solid state double layer capacitor based on a polyether polymer electrolyte blend and nanostructured carbon black electrode composites

    NASA Astrophysics Data System (ADS)

    Lavall, Rodrigo L.; Borges, Raquel S.; Calado, Hállen D. R.; Welter, Cezar; Trigueiro, João P. C.; Rieumont, Jacques; Neves, Bernardo R. A.; Silva, Glaura G.

    An all solid double layer capacitor was assembled by using poly(ethylene oxide)/poly(propylene glycol)- b-poly(ethylene glycol)- b-poly(propylene glycol)-bis(2-aminopropyl ether) blend (PEO-NPPP) and LiClO 4 as polymer electrolyte layer and PEO-NPPP-carbon black (CB) as electrode film. High molecular weight PEO and the block copolymer NPPP with molecular mass of 2000 Da were employed, which means that the design is safe from the point of view of solvent or plasticizer leakage and thus, a separator is not necessary. Highly conductive with large surface area nanostructured carbon black was dispersed in the polymer blend to produce the electrode composite. The electrolyte and electrode multilayers prepared by spray were studied by differential scanning calorimetry, atomic force microscopy (AFM) and impedance spectroscopy. The ionic conductivity as a function of temperature was fitted with the Williams-Landel-Ferry equation, which indicates a conductivity mechanism typical of solid polymer electrolyte. AFM images of the nanocomposite electrode showed carbon black particles of approximately 60 nm in size well distributed in a semicrystalline and porous polymer blend coating. The solid double layer capacitor with 10 wt.% CB was designed with final thickness of approximately 130 μm and delivered a capacitance of 17 F g -1 with a cyclability of more than 1000 cycles. These characteristics make possible the construction of a miniature device in complete solid state which will avoid electrolyte leakage and present a performance superior to other similar electric double layer capacitors (EDLCs) presented in literature, as assessed in specific capacitance by total carbon mass.

  3. Water based, solution-processable, transparent and flexible graphene oxide composite as electrodes in organic solar cell application

    NASA Astrophysics Data System (ADS)

    Lima, L. F.; Matos, C. F.; Gonçalves, L. C.; Salvatierra, R. V.; Cava, C. E.; Zarbin, A. J. G.; Roman, L. S.

    2016-03-01

    In this work we propose an easy method to achieve a conductive, transparent and flexible graphene oxide (GO)-based composite thin film from an aqueous dispersion. We investigated the blend ratio between GO and the conjugated polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) by comparing the thin film optical transmittance, sheet resistance, morphology and mechanical stability. It was found that reasonable values of transmittance and resistivity coupled with its excellent flexibility - the conductivity remains almost the same even after 1000 bends cycles - make this composite very attracting for flexible optoelectronic applications. Thus, these films were used as transparent electrodes in a bilayer structured organic solar cell and the device architecture PET/GO:PEDOT/F8T2/C60/Al could reach a power conversion efficiency around 1.10%. This result presents a better performance compared with pristine PEDOT produced with similar parameters.

  4. High-performance binder-free supercapacitor electrode by direct growth of cobalt-manganese composite oxide nansostructures on nickel foam

    PubMed Central

    2014-01-01

    A facile approach composed of hydrothermal process and annealing treatment is proposed to directly grow cobalt-manganese composite oxide ((Co,Mn)3O4) nanostructures on three-dimensional (3D) conductive nickel (Ni) foam for a supercapacitor electrode. The as-fabricated porous electrode exhibits excellent rate capability and high specific capacitance of 840.2 F g-1 at the current density of 10 A g-1, and the electrode also shows excellent cycling performance, which retains 102% of its initial discharge capacitance after 7,000 cycles. The fabricated binder-free hierarchical composite electrode with superior electrochemical performance is a promising candidate for high-performance supercapacitors. PMID:25258611

  5. Nanostructured Fe2O3 and CuO composite electrodes for Li ion batteries synthesized and deposited in one step

    NASA Astrophysics Data System (ADS)

    García-Tamayo, E.; Valvo, M.; Lafont, U.; Locati, C.; Munao, D.; Kelder, E. M.

    2011-08-01

    Nanostructured composite electrodes based on iron and copper oxides for applications in Li-ion batteries are produced by Electrostatic spray pyrolysis (ESP). The electrodes are directly formed by electrospraying precursor solutions containing either iron or copper salts dissolved in N-methylpyrrolidone (NMP) together with polyvinylidene fluoride (PVdF) as binder. The morphology and the structure of the deposited electrodes are investigated by X-ray diffraction (XRD) and Transmission electron microscopy (TEM), which show that sub-micrometric deposits are formed as a composite of oxide nanoparticles of a few nanometers in a PVdF polymer matrix. Electrochemical characterization by cyclic voltammetry (CV) and galvanostatic charge-discharge tests demonstrate that the conversion reactions in these electrodes enable initial discharge capacities of about 800 mAh g-1 and 1550 mAh g-1 for CuO and Fe2O3, respectively. The capacity retention in both cases needs further improvements.

  6. Enhanced electrochemical performance of porous activated carbon by forming composite with graphene as high-performance supercapacitor electrode material

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Hang; Yang, Jia-Ying; Wu, Xiong-Wei; Chen, Xiao-Qing; Yu, Jin-Gang; Wu, Yu-Ping

    2017-02-01

    In this work, a novel activated carbon containing graphene composite was developed using a fast, simple, and green ultrasonic-assisted method. Graphene is more likely a framework which provides support for activated carbon (AC) particles to form hierarchical microstructure of carbon composite. Scanning electron microscope (SEM), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET) surface area measurement, thermogravimetric analysis (TGA), Raman spectra analysis, XRD, and XPS were used to analyze the morphology and surface structure of the composite. The electrochemical properties of the supercapacitor electrode based on the as-prepared carbon composite were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), charge/discharge, and cycling performance measurements. It exhibited better electrochemical performance including higher specific capacitance (284 F g-1 at a current density of 0.5 A g-1), better rate behavior (70.7% retention), and more stable cycling performance (no capacitance fading even after 2000 cycles). It is easier for us to find that the composite produced by our method was superior to pristine AC in terms of electrochemical performance due to the unique conductive network between graphene and AC.

  7. Dispersion of nanocrystalline Fe3O4 within composite electrodes: Insights on battery-related electrochemistry

    SciTech Connect

    David C. Bock; Takeuchi, Kenneth J.; Pelliccione, Christopher J.; Zhang, Wei; Wang, Jiajun; Knehr, K. W.; Wang, Jun; Wang, Feng; West, Alan C.; Marschilok, Amy C.; Takeuchi, Esther S.

    2016-04-20

    Aggregation of nanosized materials in composite lithium-ion-battery electrodes can be a significant factor influencing electrochemical behavior. In this study, aggregation was controlled in magnetite, Fe3O4, composite electrodes via oleic acid capping and subsequent dispersion in a carbon black matrix. A heat treatment process was effective in the removal of the oleic acid capping agent while preserving a high degree of Fe3O4 dispersion. Electrochemical testing showed that Fe3O4 dispersion is initially beneficial in delivering a higher functional capacity, in agreement with continuum model simulations. However, increased capacity fade upon extended cycling was observed for the dispersed Fe3O4 composites relative to the aggregated Fe3O4 composites. X-ray absorption spectroscopy measurements of electrodes post cycling indicated that the dispersed Fe3O4 electrodes are more oxidized in the discharged state, consistent with reduced reversibility compared with the aggregated sample. Higher charge-transfer resistance for the dispersed sample after cycling suggests increased surface-film formation on the dispersed, high-surface-area nanocrystalline Fe3O4 compared to the aggregated materials. Furthermore, this study provides insight into the specific effects of aggregation on electrochemistry through a multiscale view of mechanisms for magnetite composite electrodes.

  8. Effects of activated carbon characteristics on the electrosorption capacity of titanium dioxide/activated carbon composite electrode materials prepared by a microwave-assisted ionothermal synthesis method.

    PubMed

    Liu, Po-I; Chung, Li-Ching; Ho, Chia-Hua; Shao, Hsin; Liang, Teh-Ming; Horng, Ren-Yang; Chang, Min-Chao; Ma, Chen-Chi M

    2015-05-15

    Titanium dioxide (TiO2)/ activated carbon (AC) composite materials, as capacitive deionization electrodes, were prepared by a two-step microwave-assisted ionothermal synthesis method. The electrosorption capacity of the composite electrodes was studied and the effects of AC characteristics were explored. These effects were investigated by multiple analytical techniques, including X-ray photoelectron spectroscopy, thermogravimetry analysis and electrochemical impedance spectroscopy, etc. The experimental results indicated that the electrosorption capacity of the TiO2/AC composite electrode is dependent on the characteristics of AC including the pore structure and the surface property. An enhancement in electrosorption capacity was observed for the TiO2/AC composite electrode prepared from the AC with higher mesopore content and less hydrophilic surface. This enhancement is due to the deposition of anatase TiO2 with suitable amount of Ti-OH. On the other hand, a decline in electrosorption capacity was observed for the TiO2/AC composite electrode prepared from the AC with higher micropore content and highly hydrophilic surface. High content of hydrogen bond complex formed between the functional group on hydrophilic surface with H2O, which will slow down the TiO2 precursor-H2O reaction. In such situation, the effect of TiO2 becomes unfavorable as the loading amount of TiO2 is less and the micropore can also be blocked.

  9. Optimized spherical manganese oxide-ferroferric oxide-tin oxide ternary composites as advanced electrode materials for supercapacitors.

    PubMed

    Zhu, Jian; Tang, Shaochun; Vongehr, Sascha; Xie, Hao; Meng, Xiangkang

    2015-09-18

    Inexpensive MnO2 is a promising material for supercapacitors (SCs), but its application is limited by poor electrical conductivity and low specific surface area. We design and fabricate hierarchical MnO2-based ternary composite nanostructures showing superior electrochemical performance via doping with electrochemically active Fe3O4 in the interior and electrically conductive SnO2 nanoparticles in the surface layer. Optimization composition results in a MnO2-Fe3O4-SnO2 composite electrode material with 5.9 wt.% Fe3O4 and 5.3 wt.% SnO2, leading to a high specific areal capacitance of 1.12 F cm(-2) at a scan rate of 5 mV s(-1). This is two to three times the values for MnO2-based binary nanostructures at the same scan rate. The low amount of SnO2 almost doubles the capacitance of porous MnO2-Fe3O4 (before SnO2 addition), which is attributed to an improved conductivity and remaining porosity. In addition, the optimal ternary composite has a good rate capability and an excellent cycling performance with stable capacitance retention of ~90% after 5000 charge/discharge cycles at 7.5 mA cm(-2). All-solid-state SCs are assembled with such electrodes using polyvinyl alcohol/Na2SO4 electrolyte. An integrated device made by connecting two identical SCs in series can power a light-emitting diode indicator for more than 10 min.

  10. Determination of arbutin and bergenin in Bergeniae Rhizoma by capillary electrophoresis with a carbon nanotube-epoxy composite electrode.

    PubMed

    Zhang, Luyan; Zhang, Wei; Chen, Gang

    2015-11-10

    This report describes the fabrication and the application of a novel carbon nanotube (CNT)-epoxy composite electrode as a sensitive amperometric detector for the capillary electrophoresis (CE). The composite electrode was fabricated on the basis of the in situ polycondensation of a mixture of CNTs and 1,2-ethanediamine-containing bisphenol A epoxy resin in the inner bore of a piece of fused silica capillary under heat. It was coupled with CE for the separation and detection of arbutin and bergenin in Bergeniae Rhizoma, a traditional Chinese medicine, to demonstrate its feasibility and performance. The two phenolic constituents were well separated within 10min in a 45cm capillary length at a separation voltage of 12kV using a 50mM borate buffer (pH 9.2). The CNT-based detector offered higher sensitivity, significantly lower operating potential, satisfactory resistance to surface fouling, and lower expense of operation, indicating great promise for a wide range of analytical applications. It showed long-term stability and reproducibility with relative standard deviations of less than 5% for the peak current (n=15).

  11. Amperometric L-lysine enzyme electrodes based on carbon nanotube/redox polymer and graphene/carbon nanotube/redox polymer composites.

    PubMed

    Kaçar, Ceren; Erden, Pınar Esra; Kılıç, Esma

    2017-04-01

    Highly sensitive L-lysine enzyme electrodes were constructed by using poly(vinylferrocene)-multiwalled carbon nanotubes-gelatine (PVF/MWCNTs-GEL) and poly(vinylferrocene)-multiwalled carbon nanotubes-gelatine-graphene (PVF/MWCNTs-GEL/GR) composites as sensing interfaces and their performances were evaluated. Lysine oxidase (LO) was immobilized onto the composite modified glassy carbon electrodes (GCE) by crosslinking using glutaraldehyde and bovine serum albumin. Effects of pH value, enzyme loading, applied potential, electrode composition, and interfering substances on the amperometric response of the enzyme electrodes were discussed. The analytical characteristics of the enzyme electrodes were also investigated. The linear range, detection limit, and sensitivity of the LO/PVF/MWCNTs-GEL/GCE were 9.9 × 10(-7)-7.0 × 10(-4) M, 1.8 × 10(-7) M (S/N = 3), and 13.51 μA mM(-1) cm(-2), respectively. PVF/MWCNTs-GEL/GR-based L-lysine enzyme electrode showed a short response time (<5 s) and a linear detection range from 9.9 × 10(-7) to 7.0 × 10(-4) M with good sensitivity of 17.8 μA mM(-1) cm(-2) and a low detection limit of 9.2 × 10(-8) M. The PVF/MWCNTs-GEL/GR composite-based L-lysine enzyme electrode exhibited about 1.3-fold higher sensitivity than its MWCNTs-based counterpart and its detection limit was superior to the MWCNTs-based one. In addition, enzyme electrodes were successfully applied to determine L-lysine in pharmaceutical sample and cheese.

  12. Changes in the electrical properties of the electrode-skin-underlying tissue composite during a week-long programme of neuromuscular electrical stimulation.

    PubMed

    Bîrlea, S I; Breen, P P; Corley, G J; Bîrlea, N M; Quondamatteo, F; ÓLaighin, G

    2014-02-01

    Particular neuromuscular electrical stimulation (NMES) applications require the use of the same electrodes over a long duration (>1 day) without having access to them. Under such circumstance the quality of the electrode-skin contact cannot be assessed. We used the NMES signal itself to assess the quality of the electrode-skin contact and the electrical properties of the underlying tissues over a week. A 14% decrease in the skin's stratum corneum resistance (from 20 to 17 kΩ) and a 15% decrease in the resistance of the electrodes and underlying tissues (from 550 to 460 Ω) were observed in the 14 healthy subjects investigated. A follow-on investigation of the effect of exercise-induced sweating on the electrical properties of the electrode-skin-underlying tissue composite during NMES indicated a correlation between the decrease in the resistance values observed over the course of the week and the accumulation of sweat at the electrode-skin interface. The value of the capacitance representing the dielectric properties of the skin's stratum corneum increased after exercise-induced sweating but did not change significantly over the course of the week. We conclude that valuable information about the electrode-skin-underlying tissue composite can be gathered using the NMES signal itself, and suggest that this is a practical, safe and relatively simple method for monitoring these electrical properties during long-term stimulation.

  13. Sensitive voltammetric determination of vanillin with an AuPd nanoparticles-graphene composite modified electrode.

    PubMed

    Shang, Lei; Zhao, Faqiong; Zeng, Baizhao

    2014-05-15

    In this work, graphene oxide was reduced to graphene with an endogenous reducing agent from dimethylformamide, and then AuPd alloy nanoparticles were electrodeposited on the graphene film. The obtained AuPd-graphene hybrid film was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and voltammetry. The electrochemical behavior of vanillin was studied using the AuPd-graphene hybrid based electrode. It presented high electrocatalytic activity and vanillin could produce a sensitive oxidation peak at it. Under the optimal conditions, the peak current was linear to the concentration of vanillin in the ranges of 0.1-7 and 10-40 μM. The sensitivities were 1.60 and 0.170 mA mM(-1) cm(-2), respectively; the detection limit was 20 nM. The electrode was successfully applied to the detection of vanillin in vanilla bean, vanilla tea and biscuit samples.

  14. Nickel Nanofoam/Different Phases of Ordered Mesoporous Carbon Composite Electrodes for Superior Capacitive Energy Storage.

    PubMed

    Lee, Kangsuk; Song, Haeni; Lee, Kwang Hoon; Choi, Soo Hyung; Jang, Jong Hyun; Char, Kookheon; Son, Jeong Gon

    2016-08-31

    Electrochemical energy storage devices based on electric double layer capacitors (EDLCs) have received considerable attention due to their high power density and potential for obtaining improved energy density in comparison to the lithium ion battery. Ordered mesoporous carbon (OMC) is a promising candidate for use as an EDLC electrode because it has a high specific surface area (SSA), providing a wider charge storage space and size-controllable mesopore structure with a long-range order, suppling high accessibility to the electrolyte ions. However, OMCs fabricated using conventional methods have several drawbacks including low electronic conductivity and long ionic diffusion paths in mesopores. We used nickel nanofoam, which has a relatively small pore (sub-100 nm to subμm) network structure, as a current collector. This provides a significantly shortened electronic/ionic current paths and plentiful surface area, enabling stable and close attachment of OMCs without the use of binders. Thus, we present hierarchical binder-free electrode structures based on OMC/Ni nanofoams. These structures give rise to enhanced specific capacitance and a superior rate capability. We also investigated the mesopore structural effect of OMCs on electrolyte transport by comparing the capacitive performances of collapsed lamellar, cylindrical, and spherical mesopore electrodes. The highly ordered and straightly aligned cylindrical OMCs exhibited the highest specific capacitance and the best rate capability.

  15. Electrically and mechanically enhanced Ag nanowires-colorless polyimide composite electrode for flexible capacitive sensor

    NASA Astrophysics Data System (ADS)

    Kim, Dae-Gon; Kim, Jiwan; Jung, Seung-Boo; Kim, Young-Sung; Kim, Jong-Woong

    2016-09-01

    Silver nanowire (AgNW) network is known for its low percolation threshold, high conductivity and good flexibility, therefore, considered one of the best candidates for fabrication of flexible and transparent electrodes. However, a general approach to make the AgNWs-based electrodes, an overcoating of nanowire dispersion onto a transparent polymer, should make an issue of poor mechanical stability, mainly caused by low adhesion between the nanowires and polymer. In addition, a thin insulating layer of polyvinylpyrrolidone (PVP) formed on the surface of AgNWs deteriorates the conductivity of their network, which means that a post-processing such as high temperature annealing is essentially needed. Here we employed a plasma treatment with an inert gas to remove the residual PVP layer, so that the conductivity could be enhanced without employing any high temperature processing. Interestingly, the optical transmittance in the wavelength near 400 nm was also increased, resulting in more neutral coloration of the electrode. An inverted layer processing made the nanowires to be partially buried at the surface of colorless polyimide (cPI), so that the enhancement of mechanical stability and connectivity with overlying materials were simultaneously achieved.

  16. Hierarchical composites of polyaniline-graphene nanoribbons-carbon nanotubes as electrode materials in all-solid-state supercapacitors.

    PubMed

    Liu, Mingkai; Miao, Yue-E; Zhang, Chao; Tjiu, Weng Weei; Yang, Zhibin; Peng, Huisheng; Liu, Tianxi

    2013-08-21

    A three dimensional (3D) polyaniline (PANI)-graphene nanoribbon (GNR)-carbon nanotube (CNT) composite, PANI-GNR-CNT, has been prepared via in situ polymerization of an aniline monomer on the surface of a GNR-CNT hybrid. Here, the 3D GNR-CNT hybrid has been conveniently prepared by partially unzipping the pristine multi-walled CNTs, while the residual CNTs act as "bridges" connecting different GNRs. The morphology and structure of the resulting hybrid materials have been characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy and X-ray diffraction (XRD). Electrochemical tests reveal that the hierarchical PANI-GNR-CNT composite based on the two-electrode cell possesses much higher specific capacitance (890 F g(-1)) than the GNR-CNT hybrid (195 F g(-1)) and neat PANI (283 F g(-1)) at a discharge current density of 0.5 A g(-1). At the same time, the PANI-GNR-CNT composite displays good cycling stability with a retention ratio of 89% after 1000 cycles, suggesting that this novel PANI-GNR-CNT composite is a promising candidate for energy storage applications.

  17. Well-defined flake-like polypyrrole grafted graphene nanosheets composites as electrode materials for supercapacitors with enhanced cycling stability

    NASA Astrophysics Data System (ADS)

    Wang, Xue; Wang, Tingmei; Yang, Chao; Li, Haidong; Liu, Peng

    2013-12-01

    Well-defined flake-like polypyrrole grafted graphene nanosheets composites (PPy-g-GNS) were fabricated by the in-situ chemical oxidative grafting polymerization of pyrrole in the presence of the 4-aminophenyl modified graphene nanosheets (AP-GNS), which were prepared via the coupling reaction of the graphene nanosheets (GNS) with diazonium salt. The flake-like PPy-g-GNS composite showed the high conductivity at room temperature. A maximum discharge capacitance of 191.2 F/g at the scan rate of 10 mV/s could be achieved in the three-electrode cell electrochemical testing in 1.0 mol/L NaNO3 electrolyte solution. It is higher than those of the AP-GNS, pure PPy, and the GNS/PPy composite prepared with the unmodified graphene nanosheets (GNS). The flake-like PPy-g-GNS composites also exhibited the excellent electrochemical stability even after 1000 cycles. It revealed the synergistic effect between the conducting polymer and the carbon-based support.

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

    PubMed

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

    2014-12-23

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

  19. A sensitive determination of terbutaline in pharmaceuticals and urine samples using a composite electrode based on zirconium oxide nanoparticles.

    PubMed

    Baytak, Aysegul Kutluay; Teker, Tugce; Duzmen, Sehriban; Aslanoglu, Mehmet

    2016-10-01

    An accurate and precise determination of terbutaline has been carried out using a glassy carbon electrode (GCE) modified with a composite of multi-walled carbon nanotubes (MWCNTs) and nanoparticles of zirconium oxide (ZrO2NPs). Energy dispersive X-ray and scanning electron microscopic techniques were utilized for the characterization of the composite layer. Terbutaline exhibited a broad oxidation peak at 770mV on a GCE. However, MWCNTs/GCE presented an electrocatalytic effect toward the oxidation of terbutaline with a better anodic peak at 660mV. Furthermore, the electrochemical behavior of terbutaline has greatly been improved at a GCE modified with a composite of MWCNTs and nanoparticles of ZrO2. The ZrO2NPs/MWCNTs/GCE exhibited a sharp anodic wave at 645mV with a large enhancement of the current response for terbutaline. Square wave voltammetry (SWV) was performed for the determination of terbutaline at ZrO2NPs/MWCNTs/GCE. A linear plot was obtained for the current responses of terbutaline against concentrations in the range of 10-160nM yielding a detection limit of 2.25nM (based on 3Sb/m). Improved voltammetric behavior, long-time stability and good reproducibility were obtained for terbutaline at the proposed electrode. A mean recovery of 101.2% with an RSD% of 1.9 was obtained for the analysis of the drug formulation. The accurate and precise quantification of terbutaline makes the ZrO2NPs/MWCNTs/GCE system of great interest for monitoring its therapeutic use.

  20. Freestanding three-dimensional graphene/MnO2 composite networks as ultralight and flexible supercapacitor electrodes.

    PubMed

    He, Yongmin; Chen, Wanjun; Li, Xiaodong; Zhang, Zhenxing; Fu, Jiecai; Zhao, Changhui; Xie, Erqing

    2013-01-22

    A lightweight, flexible, and highly efficient energy management strategy is needed for flexible energy-storage devices to meet a rapidly growing demand. Graphene-based flexible supercapacitors are one of the most promising candidates because of their intriguing features. In this report, we describe the use of freestanding, lightweight (0.75 mg/cm(2)), ultrathin (<200 μm), highly conductive (55 S/cm), and flexible three-dimensional (3D) graphene networks, loaded with MnO(2) by electrodeposition, as the electrodes of a flexible supercapacitor. It was found that the 3D graphene networks showed an ideal supporter for active materials and permitted a large MnO(2) mass loading of 9.8 mg/cm(2) (~92.9% of the mass of the entire electrode), leading to a high area capacitance of 1.42 F/cm(2) at a scan rate of 2 mV/s. With a view to practical applications, we have further optimized the MnO(2) content with respect to the entire electrode and achieved a maximum specific capacitance of 130 F/g. In addition, we have also explored the excellent electrochemical performance of a symmetrical supercapacitor (of weight less than 10 mg and thickness ~0.8 mm) consisting of a sandwich structure of two pieces of 3D graphene/MnO(2) composite network separated by a membrane and encapsulated in polyethylene terephthalate (PET) membranes. This research might provide a method for flexible, lightweight, high-performance, low-cost, and environmentally friendly materials used in energy conversion and storage systems for the effective use of renewable energy.

  1. Experimental and Morphological Investigations Into Electrical Discharge Surface Grinding (EDSG) of 6061Al/Al2O3p 10% Composite by Composite Tool Electrode

    NASA Astrophysics Data System (ADS)

    Kumar, Harmesh; Choudhary, Rajesh; Singh, Shankar

    2014-04-01

    In this study, a special experimental setup of EDSG using EDM and surface grinding machine has been developed in the laboratory to investigate the effect of seven input parameters namely tool polarity, peak current, pulse on-time, pulse off-time, rotational speed, abrasive particle size, and abrasive particle concentration on material removal rate (MRR) as performance measure of the process. The novelty of the present research work is that successful efforts have been made to machine the 6061Al/Al2O3p 10% metal matrix composites (MMC) by composite tool itself. The copper-based composite tool electrodes were fabricated by powder metallurgy route with different sizes of abrasives of silicon carbide, while 6061Al/Al2O3p 10% MMC were fabricated through stir-casting process. The research outcome will identify the important parameters and their effect on MRR of 6061Al/Al2O3p 10% composite in EDSG. The experimental results reveal that tool polarity, peak current, and rotational speed are the most influential parameters that affect MRR in EDSG process. The micro-structural and morphological analysis of machined surfaces has also been carried out to analyze the surface topography. It has been concluded that the abrasive particles substantially improves the MRR after removing the resolidified layer from the machined surface.

  2. Multiscale simulation process and application to additives in porous composite battery electrodes

    NASA Astrophysics Data System (ADS)

    Wieser, Christian; Prill, Torben; Schladitz, Katja

    2015-03-01

    Structure-resolving simulation of porous materials in electrochemical cells such as fuel cells and lithium ion batteries allows for correlating electrical performance with material morphology. In lithium ion batteries characteristic length scales of active material particles and additives range several orders of magnitude. Hence, providing a computational mesh resolving all length scales is not reasonably feasible and requires alternative approaches. In the work presented here a virtual process to simulate lithium ion batteries by bridging the scales is introduced. Representative lithium ion battery electrode coatings comprised of μm-scale graphite particles as active material and a nm-scale carbon/polymeric binder mixture as an additive are imaged with synchrotron radiation computed tomography (SR-CT) and sequential focused ion beam/scanning electron microscopy (FIB/SEM), respectively. Applying novel image processing methodologies for the FIB/SEM images, data sets are binarized to provide a computational grid for calculating the effective mass transport properties of the electrolyte phase in the nanoporous additive. Afterwards, the homogenized additive is virtually added to the micropores of the binarized SR-CT data set representing the active particle structure, and the resulting electrode structure is assembled to a virtual half-cell for electrochemical microheterogeneous simulation. Preliminary battery performance simulations indicate non-negligible impact of the consideration of the additive.

  3. Novel mesoporous carbon ceramics composites as electrodes for direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Gallo, Jean Marcel R.; Gatti, Giorgio; Graizzaro, Alessandro; Marchese, Leonardo; Pastore, Heloise O.

    2011-10-01

    In this work, a new family of materials for electrodes of direct methanol fuel cell (DMFC) is presented. Mesoporous carbon ceramics (MCCs) are obtained by the addition of commercial graphite into the synthesis gel of SBA-15 mesoporous silica with SiO2/C weight ratios of 1/1 and 1/3. X-ray diffraction confirms both the formation of organized silica and the presence of graphite, and nitrogen physisorption measurements show that the presence of a graphitic phase does not interfere in the silica pore diameter although it diminishes the surface area. The MCCs modified with Pt or PtRu are tested as DMFC electrodes and compared with the commercial support Vulcan XC-72R. When used as cathode, the system using MCC-SBA-15 with SiO2/C weight ratios of 1/1 presents a negligible performance, while the MCC-SBA-15 with SiO2/C weight ratios of 1/3 is 2.9 times less active than the commercial support. On the other side, when used as anode, the MCC-SBA-15 with SiO2/C weight ratios of 1/3 displays performances comparable to Vulcan XC-72R.

  4. Silver nanoflower-reduced graphene oxide composite based micro-disk electrode for insulin detection in serum.

    PubMed

    Yagati, Ajay Kumar; Choi, Yonghyun; Park, Jinsoo; Choi, Jeong-Woo; Jun, Hee-Sook; Cho, Sungbo

    2016-06-15

    Sensitive and selective determination of protein biomarkers remains a significant challenge due to the existence of various biomarkers in human body at a low concentration level. Therefore, new technologies were incessantly steered to detect tiny biomarkers at a low concentration level, yet, it is difficult to develop reliable, stable and sensitive detection methods for disease diagnostics. Therefore, the present study demonstrates a methodology to detect insulin in serum at low levels based on Ag nanoflower (AgNF) decorated reduced graphene oxide (rGO) modified micro-disk electrode arrays (MDEAs). The morphology of AgNF-rGO composite was characterized by scanning electron microscopy, the structure was analyzed using X-ray diffraction patterns and Raman spectra. The hybrid interface exhibited enhanced electrical conductivity when compared with its individual elements and had improved capturing ability for antibody-antigen binding towards insulin detection. In order to measure quantitatively the insulin concentration in PBS and human serum, the change in impedance (ΔZ) from electrochemical impedance spectroscopy was analyzed for various concentrations of insulin in [Fe(CN)6](3-/4-) redox couple. The electrode with adsorbed antibodies showed an increase in ΔZ for the addition of antigen concentrations over a working range of 1-1000 ng mL(-1). The detection limits were 50 and 70 pg mL(-1) in PBS and human serum, respectively.

  5. A sensitive bisphenol A voltammetric sensor relying on AuPd nanoparticles/graphene composites modified glassy carbon electrode.

    PubMed

    Su, Bingyuan; Shao, Huilin; Li, Na; Chen, Xiaomei; Cai, Zhixiong; Chen, Xi

    2017-05-01

    In this work, a sensitive bisphenol A (BPA) electrochemical sensor was assembled using a surfactant-free AuPd nanoparticles-loaded graphene nanosheets (AuPdNPs/GNs) modified electrode. The AuPdNPs monodispersed on GNs were successfully prepared by the spontaneous redox reaction between bimetallic precursors and GNs. Because no surfactant or halide ions were involved in the proposed synthesis, the prepared composite was enabled to directly modify a glassy carbon electrode without any pre-treatments. Moreover, due to the synergetic effect of Au and Pd, AuPdNPs/GNs displayed high electrochemical activity with well-defined voltammetric peaks of BPA oxidation and lower overpotential compared with monometallic PdNPs and AuNPs supported GNs. According to the results of differential pulse voltammetry (DPV), under optimized conditions, a good linear response was observed for the concentration of BPA in the range of 0.05-10μM with a detection limit of 8nM. The developed electrochemical sensor was successfully applied to determine BPA in food package. This study indicated that AuPdNPs/GNs based electrochemical sensor can be a promising and reliable tool for rapid analysis of emergency pollution affairs of BPA.

  6. Electrical, Mechanical, and Capacity Percolation Leads to High-Performance MoS2/Nanotube Composite Lithium Ion Battery Electrodes.

    PubMed

    Liu, Yuping; He, Xiaoyun; Hanlon, Damien; Harvey, Andrew; Khan, Umar; Li, Yanguang; Coleman, Jonathan N

    2016-06-28

    Advances in lithium ion batteries would facilitate technological developments in areas from electrical vehicles to mobile communications. While two-dimensional systems like MoS2 are promising electrode materials due to their potentially high capacity, their poor rate capability and low cycle stability are severe handicaps. Here, we study the electrical, mechanical, and lithium storage properties of solution-processed MoS2/carbon nanotube anodes. Nanotube addition gives up to 10(10)-fold and 40-fold increases in electrical conductivity and mechanical toughness, respectively. The increased conductivity results in up to a 100× capacity enhancement to ∼1200 mAh/g (∼3000 mAh/cm(3)) at 0.1 A/g, while the improved toughness significantly boosts cycle stability. Composites with 20 wt % nanotubes combine high reversible capacity with excellent cycling stability (e.g., ∼950 mAh/g after 500 cycles at 2 A/g) and high rate capability (∼600 mAh/g at 20 A/g). The conductivity, toughness, and capacity scale with nanotube content according to percolation theory, while the stability increases sharply at the mechanical percolation threshold. We believe that the improvements in conductivity and toughness obtained after addition of nanotubes can be transferred to other electrode materials, such as silicon nanoparticles.

  7. Impedancemetric NOx Sensing Using Yttria-Stabilized Zirconia (YSZ) Electrolyte and YSZ/Cr2O3 Composite Electrodes

    SciTech Connect

    Martin, L P; Woo, L Y; Glass, R S

    2006-11-01

    An impedancemetric method for NO{sub x} sensing using an yttria-stabilized zirconia (YSZ) based electrochemical cell is described. The sensor cell consists of a planar YSZ electrolyte and two identical YSZ/Cr{sub 2}O{sub 3} composite electrodes exposed to the test gas. The sensor response to a sinusoidal ac signal applied between the two electrodes is measured via two parameters calculated from the complex impedance, the modulus |Z| and phase angle {Theta}. While either of these parameters can be correlated to the NO{sub x} concentration in the test gas, {Theta} was found to provide a more robust metric than |Z|. At frequencies below approximately 100 Hz, {Theta} is sensitive to both the NO{sub x} and O{sub 2} concentrations. At higher frequencies, {Theta} is predominantly affected by the O{sub 2} concentration. A dual frequency measurement is demonstrated to compensate for changes in the O{sub 2} background between 2 and 18.9%. Excellent sensor performance is obtained for NO{sub x} concentrations in the range of 8-50 ppm in background. An equivalent circuit model was used to extract fitting parameters from the impedance spectra for a preliminary analysis of NO{sub x} sensing mechanisms.

  8. Enhancement of the efficiency of dye-sensitized solar cell with multi-wall carbon nanotubes/polypyrrole composite counter electrodes prepared by electrophoresis/electrochemical polymerization

    SciTech Connect

    Luo, Jun; Niu, Hai-jun; Wen, Hai-lin; Wu, Wen-jun; Zhao, Ping; Wang, Cheng; Bai, Xu-duo; Wang, Wen

    2013-03-15

    Graphical abstract: The overall energy conversion efficiency of the DSSC employing the MWCNT/PPy CE reached 3.78%. Compared with a reference DSSC using single MWCNT film CE with efficiency of 2.68%, the energy conversion efficiency was increased by 41.04%. Highlights: ► MWCNT/PPy composite film prepared by electrodeposition layer by layer was used as counter electrode in DSSC. ► The overall energy conversion efficiency of the DSSC was 3.78% by employing the composite film. ► The energy conversion efficiency increased by 41.04% compared with efficiency of 2.68% by using the single MWCNT film. ► We analyzed the mechanism and influence factor of electron transfer in the composite electrode by EIS. - Abstract: For the purpose of replacing the precious Pt counter electrode in dye-sensitized solar cells (DSSCs) with higher energy conversion efficiency, multi-wall carbon nanotube (MWCNT)/polypyrrole (PPy) double layers film counter electrode (CE) was fabricated by electrophoresis and cyclic voltammetry (CV) layer by layer. Atom force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscope (TEM) demonstrated the morphologies of the composite electrode and Raman spectroscopy verified the PPy had come into being. The overall energy conversion efficiency of the DSSC employing the MWCNT/PPy CE reached 3.78%. Compared with a reference DSSC using single MWCNT film CE with efficiency of 2.68%, the energy conversion efficiency was increased by 41.04%. The result of impedance showed that the charge transfer resistance R{sub ct} of the MWCNT/PPy CE had the lowest value compared to that of MWCNT or PPy electrode. These results indicate that the composite film with high conductivity, high active surface area, and good catalytic properties for I{sub 3}{sup −} reduction can potentially be used as the CE in a high-performance DSSC.

  9. Effect of Fe2O3 and Binder on the Electrochemical Properties of Fe2O3/AB (Acetylene Black) Composite Electrodes

    NASA Astrophysics Data System (ADS)

    Anh, Trinh Tuan; Thuan, Vu Manh; Thang, Doan Ha; Hang, Bui Thi

    2017-01-01

    In an effort to find the best anode material for Fe/air batteries, a Fe2O3/AB (Acetylene Black) composite was prepared by dry-type ball milling using Fe2O3 nanoparticles and AB as the active and additive materials, respectively. The effects of various binders and Fe2O3 content on the electrochemical properties of Fe2O3/AB electrodes in alkaline solution were investigated. It was found that the content of Fe2O3 strongly affected the electrochemical behavior of Fe2O3/AB electrodes; with Fe2O3 nanopowder content reaching 70 wt.% for the electrode and showing improvement of the cyclability. When the electrode binder polytetrafluoroethylene (PTFE) was used, clear redox peaks were observed via cyclic voltammetry (CV), while polyvinylidene fluoride-containing electrodes provided CV curves with unobservable redox peaks. Increasing either binder content in the electrode showed a negative effect in terms of the cyclability of the Fe2O3/AB electrode.

  10. Carbon nanotube-graphene composite film as transparent conductive electrode for GaN-based light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Kang, Chun Hong; Shen, Chao; M. Saheed, M. Shuaib; Mohamed, Norani Muti; Ng, Tien Khee; Ooi, Boon S.; Burhanudin, Zainal Arif

    2016-08-01

    Transparent conductive electrodes (TCE) made of carbon nanotube (CNT) and graphene composite for GaN-based light emitting diodes (LED) are presented. The TCE with 533-Ω/□ sheet resistance and 88% transmittance were obtained when chemical-vapor-deposition grown graphene was fused across CNT networks. With an additional 2-nm thin NiOx interlayer between the TCE and top p-GaN layer of the LED, the forward voltage was reduced to 5.12 V at 20-mA injection current. Four-fold improvement in terms of light output power was observed. The improvement can be ascribed to the enhanced lateral current spreading across the hybrid CNT-graphene TCE before injection into the p-GaN layer.

  11. Aptasensor for electrochemical sensing of angiogenin based on electrode modified by cationic polyelectrolyte-functionalized graphene/gold nanoparticles composites.

    PubMed

    Chen, Zhengbo; Zhang, Chenmeng; Li, Xiaoxiao; Ma, He; Wan, Chongqing; Li, Kai; Lin, Yuqing

    2015-03-15

    Herein, a label-free and highly sensitive electrochemical aptasensor for the detection of angiogenin was proposed based on a conformational change of aptamer and amplification by poly(diallyldimethyl ammonium chloride) (PDDA)-functionalized graphene/gold nanoparticles (AuNPs) composites-modified electrode. PDDA-functionalized graphene (P-GR) nanosheets as the building block in the self-assembly of GR nanosheets/AuNPs heterostructure enhanced the electrochemical detection performance. The electrochemical aptasensor has an extraordinarily sensitive response to angiogenin in a linear range from 0.1pM to 5nM with a detection limit of 0.064pM. The developed sensor provides a promising strategy for the cancer diagnosis in medical application in the future.

  12. Comparison of electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb, Ge, Zr-added TiO2 composite electrodes.

    PubMed

    Imahori, Hiroshi; Hayashi, Shinya; Umeyama, Tomokazu; Eu, Seunghun; Oguro, Akane; Kang, Soonchul; Matano, Yoshihiro; Shishido, Tetsuya; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

    2006-12-19

    Electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were examined to disclose the effects of partial substitution of Ti atom by the other metals in the composite electrodes. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were prepared by sol-gel process using laurylamine hydrochloride as a template for the formation of micellar precursors yielding well-defined mesoporous nanocrystalline structures, as in the cases of the formation of silica and titania tubules and nanoparticles by the templating mechanism. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were characterized by transmission electron microscopy, BET surface area analysis, X-ray diffraction analysis, Raman spectroscopy, and impedance measurements. The TiO2 anatase nanocrystalline structure is retained after doping a small amount (5 mol %) of Nb, Ge, or Zr into the TiO2 structure, suggesting the homogeneous distribution of the doped metals with replacing Ti atom by the doped metal. The power conversion efficiency of the porphyrin-sensitized solar cells increases in the order Zr-added TiO2 (0.8%) < Nb-added TiO2 (1.2%) < TiO2 (2.0%) < Ge-added TiO2 cells (2.4%) under the same conditions. The improvement of cell performance of the Ge-added TiO2 cell results from the negative shift of the conduction band of the Ge-added TiO2 electrode. The Ge-added TiO2 cell exhibited a maximum power conversion efficiency of 3.5% when the porphyrin was adsorbed onto the surface of the Ge-added TiO2 electrode with a thickness of 4 microm in MeOH for 1 h.

  13. Determination of anthracene on Ag-Au alloy nanoparticles/overoxidized-polypyrrole composite modified glassy carbon electrodes.

    PubMed

    Mailu, Stephen N; Waryo, Tesfaye T; Ndangili, Peter M; Ngece, Fanelwa R; Baleg, Abd A; Baker, Priscilla G; Iwuoha, Emmanuel I

    2010-01-01

    A novel electrochemical sensor for the detection of anthracene was prepared by modifying a glassy carbon electrode (GCE) with over-oxidized polypyrrole (PPyox) and Ag-Au (1:3) bimetallic nanoparticles (Ag-AuNPs). The composite electrode (PPyox/Ag-AuNPs/GCE) was prepared by potentiodynamic polymerization of pyrrole on GCE followed by its overoxidation in 0.1 M NaOH. Ag-Au bimetallic nanoparticles were chemically prepared by the reduction of AgNO(3) and HAuCl(4) using C(6)H(5)O(7)Na(3) as the reducing agent as well as the capping agent and then immobilized on the surface of the PPyox/GCE. The nanoparticles were characterized by UV-visible spectroscopy technique which confirmed the homogeneous formation of the bimetallic alloy nanoparticles. Transmission electron microscopy showed that the synthesized bimetallic nanoparticles were in the range of 20-50 nm. The electrochemical behaviour of anthracene at the PPyox/Ag-AuNPs/GCE with Ag: Au atomic ratio 25:75 (1:3) exhibited a higher electrocatalytic effect compared to that observed when GCE was modified with each constituent of the composite (i.e., PPyox, Ag-AuNPs) and bare GCE. A linear relationship between anodic current and anthracene concentration was attained over the range of 3.0 × 10(-6) to 3.56 × 10(-4) M with a detection limit of 1.69 × 10(-7) M. The proposed method was simple, less time consuming and showed a high sensitivity.

  14. Nano composite membrane-electrode assembly formation for fuel cell-modeling aspects

    NASA Astrophysics Data System (ADS)

    Vaivars, G.; Linkov, V.

    2007-12-01

    Long term stability is an essential requirement for fuel cell applications in automobile and stationary energy systems. In these systems the agglomeration of the catalyst nanoparticles is a well-known phenomenon which cannot be easily overcome or compensated for by re-designing the system. A direct result of this occurrence is the irreversible decrease of the electrochemical performance. Irregularities in electric field distribution are one root cause for migration and subsequent agglomeration of the catalyst nanoparticle. In this work, the impact of the electrode mechanical deformation on electric field distribution was studied using a computer modeling approach. Model of a Proton Exchange Membrane (PEM) fuel cell with interdigitated flow field from Comsol Chemical Engineering/Electrochemical Engineering Module library was used for simulations. It was established that by minimizing the backing layer deformation it is possible to achieve some improvement in current distribution.

  15. β-Cobalt sulfide nanoparticles decorated graphene composite electrodes for high capacity and power supercapacitors.

    PubMed

    Qu, Baihua; Chen, Yuejiao; Zhang, Ming; Hu, Lingling; Lei, Danni; Lu, Bingan; Li, Qiuhong; Wang, Yanguo; Chen, Libao; Wang, Taihong

    2012-12-21

    Electrochemical supercapacitors have drawn much attention because of their high power and reasonably high energy densities. However, their performances still do not reach the demand of energy storage. In this paper β-cobalt sulfide nanoparticles were homogeneously distributed on a highly conductive graphene (CS-G) nanocomposite, which was confirmed by transmission electron microscopy analysis, and exhibit excellent electrochemical performances including extremely high values of specific capacitance (~1535 F g(-1)) at a current density of 2 A g(-1), high-power density (11.98 kW kg(-1)) at a discharge current density of 40 A g(-1) and excellent cyclic stability. The excellent electrochemical performances could be attributed to the graphene nanosheets (GNSs) which could maintain the mechanical integrity. Also the CS-G nanocomposite electrodes have high electrical conductivity. These results indicate that high electronic conductivity of graphene nanocomposite materials is crucial to achieving high power and energy density for supercapacitors.

  16. Optical properties and electrochemical dealloying of Gold-Silver alloy nanoparticles immobilized on composite thin-film electrodes

    NASA Astrophysics Data System (ADS)

    Starr, Christopher A.

    Gold-silver alloy nanoparticles (NPs) capped with adenosine 5'-triphosphate were synthesized by borohydride reduction of dilute aqueous metal precursors. High-resolution transmission electron microscopy showed the as-synthesized particles to be spherical with average diameters ~4 nm. Optical properties were measured by UV-Visible spectroscopy (UV-Vis), and the formation of alloy NPs was verified across all gold:silver ratios by a linear shift in the plasmon band maxima against alloy composition. The molar absorptivities of the NPs decreased non-linearly with increasing gold content from 2.0 x 108 M-1 cm-1 (lambdamax = 404 nm) for pure silver to 4.1 x 107 M-1 cm -1 (lambdamax = 511 nm) for pure gold. The NPs were immobilized onto transparent indium-tin oxide composite electrodes using layer-by-layer (LbL) deposition with poly(diallyldimethylammonium) acting as a cationic binder. The UV-Vis absorbance of the LbL film was used to calculate the surface coverage of alloy NPs on the electrode. Typical preparations had average NP surface coverages of 2.8 x 10-13 mol NPs/cm2 (~5% of cubic closest packing) with saturated films reaching ~20% of ccp for single-layer preparations (1.0 ~ 10-12 mol NPs/cm2). X-ray photoelectron spectroscopy confirmed the presence of alloy NPs in the LbL film and showed silver enrichment of the NP surfaces by ~9%. Irreversible oxidative dissolution (dealloying) of the less noble silver atoms from the NPs on LbL electrodes was performed by cyclic voltammetry (CV) in sulfuric acid. Alloy NPs with higher gold content required larger overpotentials for silver dealloying. Dealloying of the more-noble gold atoms from the alloy NPs was also achieved by CV in sodium chloride. The silver was oxidized first to cohesive silver chloride, and then gold dealloyed to soluble HAuCl 4- at higher potentials. Silver oxidation was inhibited during the first oxidative scan, but subsequent cycles showed typical, reversible silver-to-silver chloride voltammetry. The

  17. Integration of a graphite/poly(methyl-methacrylate) composite electrode into a poly(methylmethacrylate) substrate for electrochemical detection in microchips.

    PubMed

    Regel, Anne; Lunte, Susan

    2013-07-01

    Traditional fabrication methods for polymer microchips, the bonding of two substrates together to form the microchip, can make the integration of carbon electrodes difficult. We have developed a simple and inexpensive method to integrate graphite/PMMA composite electrodes (GPCEs) into a PMMA substrate. These substrates can be bonded to other PMMA layers using a solvent-assisted thermal bonding method. The optimal composition of the GPCEs for electrochemical detection was determined using cyclic voltammetry with dopamine as a test analyte. Using the optimized GPCEs in an all-PMMA flow cell with flow injection analysis, it was possible to detect 50 nM dopamine under the best conditions. These electrodes were also evaluated for the detection of dopamine and catechol following separation by MCE.

  18. Sensitive electrochemical detection of superoxide anion using gold nanoparticles distributed poly(methyl methacrylate)-polyaniline core-shell electrospun composite electrode.

    PubMed

    Santhosh, Padmanabhan; Manesh, Kalayil Manian; Lee, Se-Hee; Uthayakumar, Sivaperumal; Gopalan, Anantha Iyengar; Lee, Kwang-Pill

    2011-04-21

    In the present communication, a novel composite nanofibrous electrode is developed for the detection of superoxide anion (O(2)˙(-)) in phosphate buffered saline (PBS). The composite fiber electrode is fabricated by dispersing gold nanoparticles onto poly(methyl methacrylate) (PMMA)-polyaniline (PANI) core-shell electrospun nanofibers. The constructed architecture is proven to be a favorable environment for the immobilization of the enzyme, superoxide dismutase (SOD). Direct electron transfer is achieved between SOD and the electrode with an electron transfer rate constant of 8.93 s(-1). At an applied potential of +300 mV, PMMA/PANI-Au(nano)/SOD-ESCFM shows highly sensitive detection of O(2)˙(-). In addition to this, quantification of different activities of SOD is realized at PMMA/PANI-Au(nano)/SOD-ESCFM. These analytical features offer great potential for construction of the third-generation O(2)˙(-) biosensor.

  19. Preparation and electrochemical characterization of polyaniline/activated carbon composites as an electrode material for supercapacitors.

    PubMed

    Oh, Misoon; Kim, Seok

    2012-01-01

    Polyaniline (PANI)/activated carbon (AC) composites were prepared by a chemical oxidation polymerization. To find an optimum ratio between PANI and AC which shows superior electrochemical properties, the preparation was carried out in changing the amount of added aniline monomers. The morphology of prepared composites was investigated by scanning electron microscopy (SEM) and transmission electron microscope (TEM). The structural and thermal properties were investigated by Fourier transform infrared spectra (FT-IR) and thermal gravimetric analysis (TGA), respectively. The electrochemical properties were characterized by cyclic voltammetry (CV). Composites showed a summation of capacitances that consisted of two origins. One is double-layer capacitance by ACs and the other is faradic capacitance by redox reaction of PANI. Fiber-like PANIs are coated on the surface of ACs and they contribute to the large surface for redox reaction. The vacancy among fibers provided the better diffusion and accessibility of ion. High capacitances of composites were originated from the network structure having vacancy made by PANI fibers. It was found that the composite prepared with 5 ml of aniline monomer and 0.25 g of AC showed the highest capacitance. Capacitance of 771 F/g was obtained at a scan rate of 5 mV/s.

  20. Cobalt Sulfide/Graphene Composite Hydrogel as Electrode for High-Performance Pseudocapacitors

    PubMed Central

    Meng, Xiaoqian; Deng, Jin; Zhu, Junwu; Bi, Huiping; Kan, Erjun; Wang, Xin

    2016-01-01

    Graphene and its composite hydrogels with interconnected three-dimensional (3D) structure have raised continuous attention in energy storage. Herein, we describe a simple hydrothermal strategy to synthesize 3D CoS/graphene composite hydrogel (CGH), which contains the reduction of GO sheets and anchoring of CoS nanoparticles on graphene sheets. The formed special 3D structure endows this composite with high electrochemical performance. Remarkably, the obtained 3D CGH exhibits high specific capacitance (Cs) of 564 F g−1 at a current density of 1 A g−1 (about 1.3 times higher than pure CoS), superior rate capability and high stability. It is worth mentioning that this methodology is readily adaptable to decorating CoS nanoparticles onto graphene sheets and may be extended to the preparation of other pseudocapacitive materials based on graphene hydrogels for electrochemical applications. PMID:26880686

  1. Composite films of carbon black nanoparticles and sulfonated-polythiophene as flexible counter electrodes for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Li, Chun-Ting; Lee, Chi-Ta; Li, Sie-Rong; Lee, Chuan-Pei; Chiu, I.-Ting; Vittal, R.; Wu, Nae-Lih; Sun, Shih-Sheng; Ho, Kuo-Chuan

    2016-01-01

    A composite film based on carbon black nanoparticles and sulfonated-poly(thiophene-3-[2-(2-methoxyethoxy)ethoxy]-2,5-diyl) (CB-NPs/s-PT) is formed on a flexible titanium foil for the use as the electro-catalytic counter electrode (CE) of dye-sensitized solar cells (DSSCs). The CB-NPs provide the large amount of electro-catalytic active sites for the composite film, and the s-PT polymer serves as a conductive binder to enhance the inter-particle linkage among CB-NPs and to improve the adhesion between the composite film and the flexible substrate. The flexible CB-NPs/s-PT composite film is designed to possess good electro-catalytic ability for I-/I3- redox couple by providing large active sites and rapid reduction kinetic rate constant of I3- . The cell with a CB-NPs/s-PT CE exhibits a good cell efficiency (η) of 9.02 ± 0.01% at 100 mW cm-2, while the cell with a platinum CE shows an η of only 8.36 ± 0.02% under the same conditions. At weak light illuminations (20-80 mW cm-2), a DSSC with CB-NPs/s-PT CE still exhibits η's of 7.20 ± 0.04-9.08 ± 0.02%. The low-cost CB-NPs/s-PT CE not only renders high cell efficiency to its DSSC but also shows a great potential to replace the expensive platinum; moreover it is suitable for large-scale production or for indoor applications.

  2. Composition and crystal structure of perovskite films attained from electrodes of used car battery

    NASA Astrophysics Data System (ADS)

    Dhiaputra, Ilham; Permana, Bayu; Maulana, Yusep; Inayatie, Yuniar Dwi; Purba, Yonatan R.; Bahtiar, Ayi

    2016-02-01

    Perovskite solar cells have been intensively investigated for high performance and low-cost solid-state solar cells. Perovskite based-lead materials are commonly used as active material for high power conversion efficiency solar cells. Herein, we report our study on the development of used electrodes car battery as a cheap raw lead material to be converted into lead (II) iodide PbI2 by using simple chemical method. We have successfully obtained PbI2 material with purity higher than 85% and its crystal structure is comparable with that of commercial product. The perovskite CH3NH3PbI3 film was prepared by spin-coating of PbI2 solution and followed by spin-coating two-times of methylamonium iodide (MAI) solution. In this paper, the crystal structure of perovskite film attained from used car battery is shown and compared with that of prepared from commercial PbI2. By utilizing the used car battery into perovskite valuable material for high performance solar cells, we can not only improve the economical value (added-value) of wasted car battery but also we can simultaneously save the environment.

  3. Electrophoretic deposition of RuO2 /HRGO composites for flexible supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Amir, Fatima; Pham, Viet; Mullinax, Dakoda; Dickerson, James

    Flexible energy storage devices are essential for the development of wearable electronics, such as bendable displays and wearable multi-media systems. A subset of these energy storage devices, flexible supercapacitors have received increased attention because of their long cycle life, low cost, and easy fabrication. Herein, we report an easy and low cost method to fabricate bendable ruthenium oxide (RuO2) / holey reduced graphene oxide (HRGO) electrodes using electrophoretic deposition. Analysis of the surface morphology using scanning electron microscopy (SEM) shows a highly nanoporous structure with pores ranging from 2 to 3 nm. The obtained RuO2/HRGO supercapacitor exhibited excellent electrochemical capacitive performance in a PVA-H2SO4 gel electrolyte, with a specific capacitance of 418.5F/g. Additionally, a high rate performance with capacitance retention of 85% was observed when the current was increased by a factor of 20 from 1.0 to 20.0 A/g. The supercapacitor exhibited an exceptional cycling stability of 88.5% after 10,000 cycles, indicating excellent long term electrochemical stability.

  4. Ultrasensitive electrochemiluminescence detection of DNA based on nanoporous gold electrode and PdCu@carbon nanocrystal composites as labels.

    PubMed

    Yan, Mei; Zhang, Meng; Ge, Shenguang; Yu, Jinghua; Li, Meng; Huang, Jiadong; Liu, Su

    2012-07-21

    A sensitive electrochemiluminescence (ECL) DNA biosensor based on nanoporous gold (NPG) electrode and PdCu@carbon nanocrystals (CNCs) composites is developed. The CNCs were obtained simply by electrooxidation with abundant carboxyl groups at their surfaces. The NPG can be easily prepared by a selective dissolution of silver from silver-gold alloy in nitric acid, which has free-standing noble metal membranes with controllable three-dimensional (3D) porosity. The PdCu bimetallic nanocomposites with hierarchically hollow structures were fabricated through a simple replacement reaction using dealloyed nanoporous copper (NPC) as both a template and reducing agent. Structure characterization was obtained by means of transmission electron microscope (TEM) and scanning electron microscope (SEM) images. The PdCu@CNCs composites exhibit 6 times higher ECL intensity than the pure CNC-labeled reporter DNA. Taking advantage of dual-amplification effects of the developed probe, a limit of detection as low as 18 aM can be achieved and the assay exhibits excellent selectivity for single-mismatched DNA detection even in human serum. The proposed ECL based method should have wide applications in diagnosis of genetic diseases due to its simplicity, low cost, and high sensitivity at extremely low concentrations.

  5. Synthesis and Characterisation of Reduced Graphene Oxide/Bismuth Composite for Electrodes in Electrochemical Energy Storage Devices.

    PubMed

    Wang, Jiabin; Zhang, Han; Hunt, Michael R C; Charles, Alasdair; Tang, Jie; Bretcanu, Oana; Walker, David; Hassan, Khalil T; Sun, Yige; Šiller, Lidija

    2017-01-20

    A reduced graphene oxide/bismuth (rGO/Bi) composite was synthesized for the first time using a polyol process at a low reaction temperature and with a short reaction time (60 °C and 3 hours, respectively). The as-prepared sample is structured with 20-50 nm diameter bismuth particles distributed on the rGO sheets. The rGO/Bi composite displays a combination of capacitive and battery-like charge storage, achieving a specific capacity value of 773 C g(-1) at a current density of 0.2 A g(-1) when charged to 1 V. The material not only has good power density but also shows moderate stability in cycling tests with current densities as high as 5 A g(-1) . The relatively high abundance and low price of bismuth make this rGO/Bi material a promising candidate for use in electrode materials in future energy storage devices.

  6. Synthesis and Characterisation of Reduced Graphene Oxide/Bismuth Composite for Electrodes in Electrochemical Energy Storage Devices

    PubMed Central

    Wang, Jiabin; Zhang, Han; Hunt, Michael R. C.; Charles, Alasdair; Tang, Jie; Bretcanu, Oana; Walker, David; Hassan, Khalil T.; Sun, Yige

    2017-01-01

    Abstract A reduced graphene oxide/bismuth (rGO/Bi) composite was synthesized for the first time using a polyol process at a low reaction temperature and with a short reaction time (60 °C and 3 hours, respectively). The as‐prepared sample is structured with 20–50 nm diameter bismuth particles distributed on the rGO sheets. The rGO/Bi composite displays a combination of capacitive and battery‐like charge storage, achieving a specific capacity value of 773 C g−1 at a current density of 0.2 A g−1 when charged to 1 V. The material not only has good power density but also shows moderate stability in cycling tests with current densities as high as 5 A g−1. The relatively high abundance and low price of bismuth make this rGO/Bi material a promising candidate for use in electrode materials in future energy storage devices. PMID:28098431

  7. A Facile Electrophoretic Deposition Route to the Fe3O4/CNTs/rGO Composite Electrode as a Binder-Free Anode for Lithium Ion Battery.

    PubMed

    Yang, Yang; Li, Jiaqi; Chen, Dingqiong; Zhao, Jinbao

    2016-10-12

    Fe3O4 is regarded as an attractive anode material for lithium ion batteries (LIBs) due to its high theoretical capacity, natural abundance, and low cost. However, the poor cyclic performance resulting from the low conductivity and huge volume change during cycling impedes its application. Here we have developed a facile electrophoretic deposition route to fabricate the Fe3O4/CNTs (carbon nanotubes)/rGO (reduced graphene oxide) composite electrode, simultaneously achieving material synthesis and electrode assembling. Even without binders, the adhesion and mechanical firmness of the electrode are strong enough to be used for LIB anode. In this specific structure, Fe3O4 nanoparticles (NPs) interconnected by CNTs are sandwiched by rGO layers to form a robust network with good conductivity. The resulting Fe3O4/CNTs/rGO composite electrode exhibits much improved electrochemical performance (high reversible capacity of 540 mAh g(-1) at a very high current density of 10 A g(-1), and a remarkable capacity of 1080 mAh g(-1) can be maintained after 450 cycles at 1 A g(-1)) compared with that of commercial Fe3O4 NPs electrode.

  8. Electrochemical Selective and Simultaneous Detection of Diclofenac and Ibuprofen in Aqueous Solution Using HKUST-1 Metal-Organic Framework-Carbon Nanofiber Composite Electrode.

    PubMed

    Motoc, Sorina; Manea, Florica; Iacob, Adriana; Martinez-Joaristi, Alberto; Gascon, Jorge; Pop, Aniela; Schoonman, Joop

    2016-10-17

    In this study, the detection protocols for the individual, selective, and simultaneous determination of ibuprofen (IBP) and diclofenac (DCF) in aqueous solutions have been developed using HKUST-1 metal-organic framework-carbon nanofiber composite (HKUST-CNF) electrode. The morphological and electrical characterization of modified composite electrode prepared by film casting was studied by scanning electronic microscopy and four-point-probe methods. The electrochemical characterization of the electrode by cyclic voltammetry (CV) was considered the reference basis for the optimization of the operating conditions for chronoamperometry (CA) and multiple-pulsed amperometry (MPA). This electrode exhibited the possibility to selectively detect IBP and DCF by simple switching the detection potential using CA. However, the MPA operated under optimum working conditions of four potential levels selected based on CV shape in relation to the potential value, pulse time, and potential level number, and order allowed the selective/simultaneous detection of IBP and DCF characterized by the enhanced detection performance. For this application, the HKUST-CNF electrode exhibited a good stability and reproducibility of the results was achieved.

  9. Electrochemical Selective and Simultaneous Detection of Diclofenac and Ibuprofen in Aqueous Solution Using HKUST-1 Metal-Organic Framework-Carbon Nanofiber Composite Electrode

    PubMed Central

    Motoc, Sorina; Manea, Florica; Iacob, Adriana; Martinez-Joaristi, Alberto; Gascon, Jorge; Pop, Aniela; Schoonman, Joop

    2016-01-01

    In this study, the detection protocols for the individual, selective, and simultaneous determination of ibuprofen (IBP) and diclofenac (DCF) in aqueous solutions have been developed using HKUST-1 metal-organic framework-carbon nanofiber composite (HKUST-CNF) electrode. The morphological and electrical characterization of modified composite electrode prepared by film casting was studied by scanning electronic microscopy and four-point-probe methods. The electrochemical characterization of the electrode by cyclic voltammetry (CV) was considered the reference basis for the optimization of the operating conditions for chronoamperometry (CA) and multiple-pulsed amperometry (MPA). This electrode exhibited the possibility to selectively detect IBP and DCF by simple switching the detection potential using CA. However, the MPA operated under optimum working conditions of four potential levels selected based on CV shape in relation to the potential value, pulse time, and potential level number, and order allowed the selective/simultaneous detection of IBP and DCF characterized by the enhanced detection performance. For this application, the HKUST-CNF electrode exhibited a good stability and reproducibility of the results was achieved. PMID:27763509

  10. A cost-effective nanoporous ultrathin film electrode based on nanoporous gold/IrO2 composite for proton exchange membrane water electrolysis

    NASA Astrophysics Data System (ADS)

    Zeng, Yachao; Guo, Xiaoqian; Shao, Zhigang; Yu, Hongmei; Song, Wei; Wang, Zhiqiang; Zhang, Hongjie; Yi, Baolian

    2017-02-01

    A cost-effective nanoporous ultrathin film (NPUF) electrode based on nanoporous gold (NPG)/IrO2 composite has been constructed for proton exchange membrane (PEM) water electrolysis. The electrode was fabricated by integrating IrO2 nanoparticles into NPG through a facile dealloying and thermal decomposition method. The NPUF electrode is featured in its 3D interconnected nanoporosity and ultrathin thickness. The nanoporous ultrathin architecture is binder-free and beneficial for improving electrochemical active surface area, enhancing mass transport and facilitating releasing of oxygen produced during water electrolysis. Serving as anode, a single cell performance of 1.728 V (@ 2 A cm-2) has been achieved by NPUF electrode with a loading of IrO2 and Au at 86.43 and 100.0 μg cm-2 respectively, the electrolysis voltage is 58 mV lower than that of conventional electrode with an Ir loading an order of magnitude higher. The electrolysis voltage kept relatively constant up to 300 h (@250 mA cm-2) during the course of durability test, manifesting that NPUF electrode is promising for gas evolution.

  11. Metal-free polymer/MWCNT composite fiber as an efficient counter electrode in fiber shape dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Ali, Abid; Mujtaba Shah, Syed; Bozar, Sinem; Kazici, Mehmet; Keskin, Bahadır; Kaleli, Murat; Akyürekli, Salih; Günes, Serap

    2016-09-01

    Highly aligned multiwall carbon nanotubes (MWCNT) as fiber were modified with a conducting polymer via a simple dip coating method. Modified MWCNT exhibited admirable improvement in electrocatalytic activity for the reduction of tri-iodide in dye sensitized solar cells. Scanning electron microscopy images confirm the successful deposition of polymer on MWCNT. Cyclic voltammetry, square wave voltammetry and electrochemical impedance spectroscopy studies were carried out to investigate the inner mechanism for the charge transfer behaviour. Results from bare and modified electrodes revealed that the MWCNT/(poly (3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) composite electrode is much better at catalysing the {{{{I}}}3}-/{{{I}}}- redox couple compared to the pristine fiber electrode. The photoelectric conversion efficiency of 5.03% for the modified MWCNT electrodes was comparable with that of the conventional Pt-based electrode. The scientific results of this study reveal that MWCNT/PEDOT:PSS may be a better choice for the replacement of cost intensive electrode materials such as platinum. Good performance even after bending up to 90° and in-series connection to enhance the output voltage were also successfully achieved, highlighting the practical application of this novel device.

  12. Thickness Dependence and Percolation Scaling of Hydrogen Production Rate in MoS2 Nanosheet and Nanosheet-Carbon Nanotube Composite Catalytic Electrodes.

    PubMed

    McAteer, David; Gholamvand, Zahra; McEvoy, Niall; Harvey, Andrew; O'Malley, Eoghan; Duesberg, Georg S; Coleman, Jonathan N

    2016-01-26

    Here we demonstrate that the performance of catalytic electrodes, fabricated from liquid exfoliated MoS2 nanosheets, can be optimized by maximizing the electrode thickness coupled with the addition of carbon nanotubes. We find the current, and so the H2 generation rate, at a given potential to increase linearly with electrode thickness to up ∼5 μm after which saturation occurs. This linear increase is consistent with a simple model which allows a figure of merit to be extracted. The magnitude of this figure of merit implies that approximately two-thirds of the possible catalytically active edge sites in this MoS2 are inactive. We propose the saturation in current to be partly due to limitations associated with transporting charge through the resistive electrode to active sites. We resolve this by fabricating composite electrodes of MoS2 nanosheets mixed with carbon nanotubes. We find both the electrode conductivity and the catalytic current at a given potential to increase with nanotube content as described by percolation theory.

  13. Multi-walled carbon nanotubes/Nafion composite film modified electrode as a sensor for simultaneous determination of ondansetron and morphine.

    PubMed

    Nigović, Biljana; Sadiković, Mirela; Sertić, Miranda

    2014-05-01

    The electrochemical behavior of ondansetron was studied on the multi-walled carbon nanotubes/Nafion polymer composite modified glassy carbon electrode (MWCNTs-Nafion/GCE). The oxidation peak potential was shifted from 1.32 V to 1.18 V compared to the bare electrode indicating excellent electrocatalytic activity of immobilized film toward drug molecule. The modified electrode exhibited a remarkable enhancement effect on voltammetric response due to the synergistic effect of nanomaterial and cation-exchange polymer on the electron transfer rate, the effective electrode area and the accumulation capability. After optimizing the experimental parameters, adsorptive stripping procedure was used for the determination of ondansetron in pharmaceutical formulation. The results were satisfactory in comparison with those obtained by high-performance liquid chromatography. In addition, the MWCNTs-Nafion/GCE exhibited high selectivity in the voltammetric measurements of ondansetron and co-administrated drug morphine with potential difference of 430 mV. The response peak currents had linear relationship with drug concentration in the range of 1.0 × 10(-7)-5.0 × 10(-6)M and 1.0 × 10(-7)-4.0 × 10(-6)M with detection limits 3.1 × 10(-8) and 3.2 × 10(-8)M for ondansetron and morphine, respectively. The electrode was successfully applied for simultaneous electrochemical sensing of both drugs in human serum samples after selective accumulation at the electrode surface.

  14. Graphene-Composite Carbon Nanofiber-Based Electrodes for Energy Storage Devices

    DTIC Science & Technology

    2014-04-18

    elongated stripes of graphene, as a conductive filler of CNFs. The GNR/carbon composite nanofibers were prepared by electrospinning from poly...acrylonitrile) (PAN) containing graphene oxide nanoribbons (GONRs), and successive twisting and carbonization.The electrospinning process can exert...directional shear force coupling with the external electric field to the flow of the spinning solution. During electrospinning , the well-dispersed GONRs were

  15. Graphene/polyaniline woven fabric composite films as flexible supercapacitor electrodes.

    PubMed

    Zang, Xiaobei; Li, Xiao; Zhu, Miao; Li, Xinming; Zhen, Zhen; He, Yijia; Wang, Kunlin; Wei, Jinquan; Kang, Feiyu; Zhu, Hongwei

    2015-04-28

    We report the design and preparation of graphene and polyaniline (PANI) woven-fabric composite films by in situ electropolymerization. The introduction of PANI greatly improves the electrochemical properties of solid-state supercapacitors which possess capacitances as high as 23 mF cm(-2), and exhibit excellent cycling stability with ∼ 100% capacitance retention after 2000 cycles. The devices have displayed superior flexibility with improved areal specific capacitances to 118% during deformation.

  16. Unidirectional Composites as Electrodes/Preionization Sources for CO2 TEA Lasers.

    DTIC Science & Technology

    1979-12-01

    Appendix A. GROWTH OF UNIDIRECTIONAL OXIDE-METAL COMPOSITES.....................143 GdO3 2 3W Gd2 3 C 20 3-Mo B . LVFE PREIONIZATION SOURCE TESTS...Discharge Tests 129 17. Cathode Fall Summary for Pulsed Discharge Tests ........ ..................... . 132 B -1. Preionization Source Test Summary...146 B -2. LVFE Cathode Summary .... .............. ... 147 B -3. Field Emission from Cathode E17-1, Test HP-4 (500 torr

  17. Graphene, conducting polymer and their composites as transparent and current spreading electrode in GaN solar cells

    NASA Astrophysics Data System (ADS)

    Mahala, Pramila; Kumar, Ajay; Nayak, Sasmita; Behura, Sanjay; Dhanavantri, Chenna; Jani, Omkar

    2016-04-01

    Understanding the physics of charge carrier transport at graphene/p-GaN interface is critical for achieving efficient device functionality. Currently, the graphene/p-GaN interface is being explored as light emitting diodes, however this interface can be probed as a potential photovoltaic cell. We report the intimate interfacing of mechanically exfoliated graphene (EG), conducting polymer (PEDOT:PSS) and composite of reduced graphene oxide (rGO) and PEDOT:PSS with a wide band gap p-GaN layer. To explore their potential in energy harvesting, three heterojunction devices such as: (i) EG/p-GaN/sapphire, (ii) PEDOT:PSS/p-GaN/sapphire and (iii) PEDOT:PSS(rGO)/p-GaN/sapphire are designed and their photovoltaic characteristics are examined. It is interesting to observe that the EG/p-GaN/sapphire solar cell exhibits high open-circuit voltage of 0.545 V with low ideality factor and reverse saturation current. However, improved short circuit current density (13.7 mA/cm2) is noticed for PEDOT:PSS/p-GaN/sapphire solar cell because of enhanced conductivity accompanied by high transmittance for PEDOT:PSS. Further, the low series resistance for PEDOT:PSS(rGO)/p-GaN/sapphire is observed suggesting that the PEDOT:PSS and rGO composite is well dispersed and exhibits low interfacial resistances with p-GaN. The present investigation leverages the potential of graphene, conducting polymer and their composites as dual capability of (a) transparent and current spreading electrode and (b) an active top layer to make an intimate contact with wide bandgap p-type GaN for possible prospect towards high performance diodes, switches and solar cells.

  18. Improved performance of quantum dot-sensitized solar cells adopting a highly efficient cobalt sulfide/nickel sulfide composite thin film counter electrode

    NASA Astrophysics Data System (ADS)

    Kim, Hee-Je; Kim, Su-Weon; Gopi, Chandu V. V. M.; Kim, Soo-Kyoung; Rao, S. Srinivasa; Jeong, Myeong-Soo

    2014-12-01

    Cobalt sulfide (CoS), nickel sulfide (NiS), and cobalt sulfide/nickel sulfide (CoS/NiS) were deposited onto fluorine-doped tin oxide (FTO) substrate using a facile chemical bath deposition method and utilized as counter electrodes (CEs) for polysulfide redox reactions in CdS/CdSe quantum dot-sensitized solar cells (QDSSCs). The thickness of 750 nm and 695 nm are optimized for NiS and CoS electrodes to prepare the CoS/NiS CE. Compared to a platinum (Pt) electrode, the CoS, NiS, and composite CoS/NiS electrodes provide higher electrocatalytic activity and lower charge-transfer resistance. The combination of a QDSSC with composite CoS/NiS CE shows an improved power conversion efficiency of 3.40% under the illumination of one sun (100 mW cm-2), which is higher than the CoS (2.53%), NiS (2.61%), and Pt (1.47%) CEs. This enhancement is mainly attributed to the NiS nanoparticles deposited on CoS film, due to which the composite structure exhibits a lower charge transfer resistance (7.61 Ω) at the interface of the CE and the electrolyte, along with superior electrochemical catalytic ability. This is well supported by the cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization measurements.

  19. Effects of concentration-dependent elastic modulus on Li-ions diffusion and diffusion-induced stresses in spherical composition-gradient electrodes

    SciTech Connect

    Zhang, Kai; Li, Yong; Zheng, Bailin

    2015-09-14

    The composition-gradient electrode material is considered as one of the most promising materials for lithium-ion batteries because of its excellent electrochemical performance and thermal stability. In this work, the effects of concentration-dependent elastic modulus on Li-ions diffusion and diffusion-induce stress in the composition-gradient electrodes were studied. The coupling equations of elasticity and diffusion under both potentiostatic charging and galvanostatic charging were developed to obtain the distributions of both the Li-ions concentration and the stress. The results indicated that the effects of the concentration-dependent elastic modulus on the Li-ions diffusion and the diffusion-induce stresses are controlled by the lithiation induced stiffening factor in the composition-gradient electrodes: a low stiffening factor at the center and a high stiffening factor at the surface lead to a significant effect, whereas a high stiffening factor at the center and a low stiffening factor at the surface result in a minimal effect. The results in this work provide guidance for the selection of electrode materials.

  20. Design, simulation and characterization of a MEMS inertia switch with flexible CNTs/Cu composite array layer between electrodes for prolonging contact time

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Yang, Zhuoqing; Xu, Qiu; Chen, Wenguo; Ding, Guifu; Zhao, Xiaolin

    2015-08-01

    This paper reports an inertia switch with a flexible carbon nanotubes/copper (CNTs/Cu) composite array layer between movable and fixed electrodes, which achieves a longer contact time compared to the traditional design using rigid-to-rigid impact between electrodes. The CNTs/Cu layer is fabricated using the composite electroplating method, and the whole device is completed by multi-layer metal electroplating based on the micro-electro-mechanical systems (MEMS) process. The dynamic responses of the designed inertia switch and the contact impact between a single CNT and a fixed electrode/another CNT have both been simulated by the ANSYS finite-element-method (FEM). It is shown that the contact time of the designed inertia switch is about 100 µs under the applied 80 g half-sine-shaped acceleration in the sensing direction. Finally, the fabricated MEMS inertia switch with the flexible CNTs/Cu composite array layer between electrodes has been evaluated by a dropping hammer system. The test contact time is about112 µs, which has a good agreement with the simulation and is much longer than that of the traditional design.

  1. Brownian dynamics simulations of colloidal suspensions containing polymers as precursors of composite electrodes for lithium batteries.

    PubMed

    Cerbelaud, Manuella; Lestriez, Bernard; Guyomard, Dominique; Videcoq, Arnaud; Ferrando, Riccardo

    2012-07-24

    Dilute aqueous suspensions of silicon nanoparticles and sodium carboxymethylcellulose salt (CMC) are studied experimentally and numerically by brownian dynamics simulations. The study focuses on the adsorption of CMC on silicon and on the aggregation state as a function of the suspension composition. To perform simulations, a coarse-grained model has first been developed for the CMC molecules. Then, this model has been applied to study numerically the behavior of suspensions of silicon and CMC. Simulation parameters have been fixed on the basis of experimental characterizations. Results of brownian dynamics simulations performed with our model are found in qualitative good agreement with experiments and allow a good description of the main features of the experimental behavior.

  2. Tunable nanostructured composite with built-in metallic wire-grid electrode

    SciTech Connect

    Micheli, Davide Pastore, Roberto; Marchetti, Mario; Gradoni, Gabriele

    2013-11-15

    In this paper, the authors report an experimental demonstration of microwave reflection tuning in carbon nanostructure-based composites by means of an external voltage supplied to the material. DC bias voltages are imparted through a metal wire-grid. The magnitude of the reflection coefficient is measured upon oblique plane-wave incidence. Increasing the bias from 13 to 700 V results in a lowering of ∼20 dB, and a “blueshift” of ∼600 MHz of the material absorption resonance. Observed phenomena are ascribed to a change of the dielectric response of the carbon material. Inherently, the physical role of tunneling between nanofillers (carbon nanotubes) is discussed. Achievements aim at the realization of a tunable absorber. There are similar studies in literature that focus on tunable metamaterials operating at either optical or THz wavelengths.

  3. Two-step electrochemical synthesis of polypyrrole/reduced graphene oxide composites as efficient Pt-free counter electrode for plastic dye-sensitized solar cells.

    PubMed

    Liu, Wantao; Fang, Yanyan; Xu, Peng; Lin, Yuan; Yin, Xiong; Tang, Guangshi; He, Meng

    2014-09-24

    Polypyrrole/reduced graphene oxide (PPy/RGO) composites on the rigid and plastic conducting substrates were fabricated via a facile two-step electrochemical process at low temperature. The polypyrrole/graphene oxide (PPy/GO) composites were first prepared on the substrate with electrochemical polymerization method, and the PPy/RGO composites were subsequently obtained by electrochemically reducing the PPy/GO. The resultant PPy/GO and PPy/RGO composites were porous, in contrast to the dense and flat pristine PPy films. The cyclic voltammetry measurement revealed that resultant composites exhibited a superior catalytic performance for triiodide reduction in the order of PPy/RGO > PPy/GO > PPy. The catalytic activity of PPy/RGO was comparable to that of Pt counter electrode (CE). Under the optimal conditions, an energy conversion efficiency of 6.45% was obtained for a rigid PPy/RGO-based dye-sensitized solar cell, which is 90% of that for a thermally deposited Pt-based device (7.14%). A plastic counter electrode was fabricated by depositing PPy/RGO composites on the plastic ITO/PEN substrate, and then an all-plastic device was assembled and exhibited an energy conversion efficiency of 4.25%, comparable to that of the counterpart using a sputtered-Pt CE (4.83%) on a plastic substrate. These results demonstrated that electrochemical synthesis is a facile low-temperature method to fabricate high-performance RGO/polymer composite-based CEs for plastic DSCs.

  4. Investigation of the Alkaline Electrochemical Interface and Development of Composite Metal/Metal-Oxides for Hydrogen and Oxygen Electrodes

    NASA Astrophysics Data System (ADS)

    Bates, Michael

    electrolyte. The HER kinetics of numerous binary & ternary Ni-alloys and composite Ni/metal-oxide/C samples were evaluated in aqueous 0.1 M KOH electrolyte. Furthermore a model of the double layer interface is proposed, which helps explain the observed ensemble effect in the presence of AEI. In Chapter 3, Ni-Fe and Ni-Fe-Co mixed-metal-oxide (MMO) films were investigated for oxygen evolution reaction (OER) activity in 0.1M KOH on high surface area Raney-Nickel supports. During investigations of MMO activity, aniline was identified as a useful "capping agent" for synthesis of high-surface area MMO-polyaniline (PANI) composite materials. A Ni-Fe-Co/PANI-Raney-Ni catalyst was developed which exhibits enhanced mass-activity compared to state-of-the-art Ni-Fe OER electrocatalysts reported to date. The morphology of the MMO catalyst film on PANI/Raney-Ni support provides excellent dispersion of active-sites and should maintain high active-site utilization for catalyst loading on gas-diffusion electrodes. In Chapter 4, the de-activation of reversible-hydrogen electrode catalysts was investigated and the development of a Pt-Ir-Nx/C catalyst is reported, which exhibits significantly increased stability in the HBr/Br 2 electrolyte. In contrast a Pt-Ir/C catalyst exhibited increased tolerance to high-voltage cycling and in particular showed recovery of electrocatalytic activity after reversible de-activation (presumably from bromide adsorption and subsequent oxidative bromide stripping). Under the harshest testing conditions of high-voltage cycling or exposure to Br2 the Pt-based catalyst showed a trend in stability: Pt < Pt-Ir < Pt-Ir-Nx. (Abstract shortened by UMI.).

  5. Detection of Cd, Pb, and Cu in non-pretreated natural waters and urine with thiol functionalized mesoporous silica and Nafion composite electrodes.

    PubMed

    Yantasee, Wassana; Charnhattakorn, Busarakum; Fryxell, Glen E; Lin, Yuehe; Timchalk, Charles; Addleman, R Shane

    2008-07-14

    Electrochemical sensors have great potential for environmental monitoring of toxic metal ions in waters due to their portability, field-deployability and excellent detection limits. However, electrochemical sensors employing mercury-free approaches typically suffer from binding competition for metal ions and fouling by organic substances and surfactants in natural waters, making sample pretreatments such as wet ashing necessary. In this work, we have developed mercury-free sensors by coating a composite of thiol self-assembled monolayers on mesoporous supports (SH-SAMMS) and Nafion on glassy-carbon electrodes. With the combined benefit of SH-SAMMS as an outstanding metal preconcentrator and Nafion as an antifouling binder, the sensors could detect 0.5 pp b of Pb and 2.5 pp b of Cd in river water, Hanford groundwater, and seawater with a minimal amount of preconcentration time (few minutes) and without any sample pretreatment. The sensor could also detect 2.5 pp b of Cd, Pb, and Cu simultaneously. The electrodes have long service times and excellent single and inter-electrode reproducibility (5% R.S.D. after 8 consecutive measurements). Unlike SAMMS-carbon paste electrodes, the SAMMS-Nafion electrodes were not fouled in samples containing albumin and successfully detected Cd in human urine. Other potentially confounding factors affecting metal detection at SAMMS-Nafion electrodes were studied, including pH effect, transport resistance of metal ions, and detection interference. With the ability to reliably detect low metal concentration ranges without sample pretreatment and fouling, SAMMS-Nafion composite sensors have the potential to become the next-generation metal analyzers for environmental and bio-monitoring of toxic metals.

  6. A Metal-Free, Free-Standing, Macroporous Graphene@g-C₃N₄ Composite Air Electrode for High-Energy Lithium Oxygen Batteries.

    PubMed

    Luo, Wen-Bin; Chou, Shu-Lei; Wang, Jia-Zhao; Zhai, Yu-Chun; Liu, Hua-Kun

    2015-06-01

    The nonaqueous lithium oxygen battery is a promising candidate as a next-generation energy storage system because of its potentially high energy density (up to 2-3 kW kg(-1)), exceeding that of any other existing energy storage system for storing sustainable and clean energy to reduce greenhouse gas emissions and the consumption of nonrenewable fossil fuels. To achieve high energy density, long cycling stability, and low cost, the air electrode structure and the electrocatalysts play important roles. Here, a metal-free, free-standing macroporous graphene@graphitic carbon nitride (g-C3N4) composite air cathode is first reported, in which the g-C3N4 nanosheets can act as efficient electrocatalysts, and the macroporous graphene nanosheets can provide space for Li2O2 to deposit and also promote the electron transfer. The electrochemical results on the graphene@g-C3N4 composite air electrode show a 0.48 V lower charging plateau and a 0.13 V higher discharging plateau than those of pure graphene air electrode, with a discharge capacity of nearly 17300 mA h g(-1)(composite) . Excellent cycling performance, with terminal voltage higher than 2.4 V after 105 cycles at 1000 mA h g(-1)(composite) capacity, can also be achieved. Therefore, this hybrid material is a promising candidate for use as a high energy, long-cycle-life, and low-cost cathode material for lithium oxygen batteries.

  7. A general approach towards carbon supported metal carbide composites for cobalt redox couple based dye-sensitized solar cells as counter electrodes

    NASA Astrophysics Data System (ADS)

    Guo, Hongyue; Han, Qianji; Gao, Chenjing; Zheng, Haihuo; Zhu, Yajing; Wu, Mingxing

    2016-11-01

    In this work, a feasible method is put forward to synthesize carbon supported transition metal carbide composites (Cr3C2-C, Mo2C-C, WC-C, VC-C, NbC-C, TaC-C, and TiC-C, et al.) by utilizing metal chlorides as metal sources, and phenolic resin as carbon source. As demonstrated by the cyclic voltammetry results, the carbon supported carbide composites present higher peak current densities as well as lower peak-to-peak separations. Moreover, the electrochemical impedance spectroscopy results indicate lower charge transfer resistance over the pristine carbides. Compared with the carbides, the carbon supported carbide composites show much higher catalytic activities towards the cobalt redox couple regeneration in dye-sensitized solar cells (DSCs) as counter electrode. In the DSCs system, the devices using the TiC-C, VC-C, and WC-C composite counter electrodes display power conversion efficiencies of 8.85%. 9.75% and 9.42%, respectively, which are much higher than those of the counterparts utilizing TiC, VC and WC counter electrodes.

  8. Chitosan mediated synthesis of core/double shell ternary polyaniline/Chitosan/cobalt oxide nano composite-as high energy storage electrode material in supercapacitors

    NASA Astrophysics Data System (ADS)

    Vellakkat, Mini; Hundekkal, Devendrappa

    2016-01-01

    Nanostructured ternary composite of polyaniline (PANI), Co3O4 nanoparticles, and Chitosan (CS) has been prepared by an in situ chemical oxidation method, and the nanocomposites (CPAESCO) were used as supercapacitor electrodes. The Co3O4 nanoparticles are uniformly coated with CS and PANI layers in it. Different techniques (Fourier transform infrared spectrophotometry, x-ray diffraction, thermal gravimetric analysis, UV-visible spectroscopy, scanning electron microscopy, transmission electron microscopy and electro chemical analysis-cyclic voltammetry, galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy) were used to analyse the optical, structural, thermal, chemical and supercapacitive aspects of the nanocomposites. Core/double shell ternary composite electrode exhibits significantly increased specific capacitance than PANI/Co3O4 or PANI/CS binary composites in supercapacitors. The ternary nanocomposite with 40% nanoparticle exhibits a highest specific capacitance reaching 687 F g-1, Energy density of (95.42 Wh kg-1 at 1 A g-1) and power density of (1549 W kg-1 at 3 A g-1) and outstanding cycling performance, with, 91% capacitance retained over 5000 cycles. It is found that this unique bio compatible nano composite with synergy is a new multifunctional material which will be useful in the design of supercapacitor electrodes and other energy conversion devices too.

  9. Li/Ag2VO2PO4 batteries: the roles of composite electrode constituents on electrochemistry

    SciTech Connect

    Bock, David C.; Bruck, Andrea M.; Pelliccione, Christopher J.; Zhang, Yiman; Takeuchi, Kenneth J.; Marschilok, Amy C.; Takeuchi, Esther S.

    2016-11-01

    In this study, we utilize silver vanadium phosphorous oxide, Ag2VO2PO4, as a model system to systematically study the impact of the constituents of a composite electrode, including polymeric and conductive additives, on electrochemistry. Notably, although highly resistive, this bimetallic cathode can be discharged as a pure electroactive material in the absence of a conductive additive as it generates an in situ conductive matrix via a reduction displacement reaction resulting in the formation of silver metal nanoparticles. Also, three different electrode compositions were investigated: Ag2VO2PO4 only, Ag2VO2PO44 with binder, and Ag2VO2PO4 with binder and carbon. Constant current discharge, pulse testing and impedance spectroscopy measurements were used to characterize the electrochemical properties of the electrodes as a function of depth of discharge. In situ EDXRD was used to spatially resolve the discharge progression within the cathode by following the formation of Ag0. Ex situ XRD and EXAFS modeling were used to quantify the amount of Ag0 formed. Results indicate that the metal center reduced (V5+ or Ag+) was highly dependent on composite composition (presence of PTFE, carbon), depth of discharge (Ag0 nanoparticle formation), and spatial location within the cathode. The addition of a binder was found to increase cell polarization, and the percolation network provided by the carbon in the presence of PTFE was further increased with reduction and formation of Ag0. Lastly, this study provides insight into the factors controlling the electrochemistry of resistive active materials in composite electrodes.

  10. Construction of a new selective coated disk electrode for Ag (I) based on modified polypyrrole-carbon nanotubes composite with new lariat ether.

    PubMed

    Abbaspour, A; Tashkhourian, J; Ahmadpour, S; Mirahmadi, E; Sharghi, H; Khalifeh, R; Shahriyari, M R

    2014-01-01

    A poly (vinyl chloride) (PVC) matrix membrane ion-selective electrode for silver (I) ion is fabricated based on modified polypyrrole - multiwalled carbon nanotubes composite with new lariat ether. This sensor has a Nernstian slope of 59.4±0.5mV/decade over a wide linear concentration range of 1.0×10(-7) to 1.0×10(-1)molL(-1) for silver (I) ion. It has a short response time of about 8.0s and can be used for at least 50days. The detection limit is 9.3×10(-8)molL(-1) for silver (I) ion, and the electrode was applicable in the wide pH range of 1.6 -7.7. The electrode shows good selectivity for silver ion against many cations such as Hg (II), which usually imposes serious interference in the determination of silver ion concentration. The use of multiwalled carbon nanotubes (MWCNTs) in a polymer matrix improves the linear range and sensitivity of the electrode. In addition by coating the solid contact with a layer of the polypyrrole (Ppy) before coating the membrane on it, not only did it reduce the drift in potential, but a shorter response time was also resulted. The proposed electrode was used as an indicator electrode for potentiometric titration of silver ions with chloride anions and in the titration of mixed halides. This electrode was successfully applied for the determination of silver ions in silver sulphadiazine as a burning cream.

  11. Facile synthesis of graphite/PEDOT/MnO2 composites on commercial supercapacitor separator membranes as flexible and high-performance supercapacitor electrodes.

    PubMed

    Tang, Pengyi; Han, Lijuan; Zhang, Li

    2014-07-09

    A facile and low-cost method is presented to synthesize graphite/PEDOT/MnO2 composites with controlled network structures on commercial supercapacitor separator (CSS) membranes for high-performance supercapacitors, in which pencil lead and a cellulose-based commercial supercapacitor separator membrane were applied as the graphite source and the flexible substrate, respectively. The dependence of PEDOT and MnO2 loading on the structural formation, the electrochemical performance of the hybrid electrode, and the formation mechanism of MnO2 nanowires are systematically investigated. The optimized electrode possesses a high areal capacitance of 316.4 mF/cm(2) at a scan rate of 10 mV/s and specific capacitance of 195.7 F/g at 0.5 A/g. The asymmetric supercapacitor device assembled using optimized CSS/Graphite/PEDOT/MnO2 electrode and activated carbon electrode exhibits a high energy density of 31.4 Wh/kg at a power density of 90 W/kg and maintains 1 Wh/kg at 4500 W/kg. After 2000 cycles, the device retains 81.1% of initial specific capacitance, and can drive a mini DC-motor for ca. 10 s. The enhanced capability of the CSS-based graphite/PEDOT/MnO2 network electrode has high potential for low-cost, high-performance, and flexible supercapacitors.

  12. Highly transparent and efficient counter electrode using SiO2/PEDOT-PSS composite for bifacial dye-sensitized solar cells.

    PubMed

    Song, Dandan; Li, Meicheng; Li, Yingfeng; Zhao, Xing; Jiang, Bing; Jiang, Yongjian

    2014-05-28

    A highly transparent and efficient counter electrode was facilely fabricated using SiO2/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) inorganic/organic composite and used in bifacial dye-sensitized solar cells (DSCs). The optical properties of SiO2/PEDOT-PSS electrode can be tailored by the blending amount of SiO2 and film thickness, and the incorporation of SiO2 in PEDOT-PSS provides better transmission in the long wavelength range. Meanwhile, the SiO2/PEDOT-PSS counter electrode shows a better electrochemical catalytic activity than PEDOT-PSS electrode for triiodide reduction, and the role of SiO2 in the catalytic process is investigated. The bifacial DSC with SiO2/PEDOT-PSS counter electrode achieves a high power conversion efficiency (PCE) of 4.61% under rear-side irradiation, which is about 83% of that obtained under front-side irradiation. Furthermore, the PCE of bifacial DSC can be significantly increased by adding a reflector to achieve bifacial irradiation, which is 39% higher than that under conventional front-side irradiation.

  13. Composition and evolution of the solid-electrolyte interphase in Na2Ti3O7 electrodes for Na-ion batteries: XPS and Auger parameter analysis.

    PubMed

    Muñoz-Márquez, Miguel A; Zarrabeitia, Maider; Castillo-Martínez, Elizabeth; Eguía-Barrio, Aitor; Rojo, Teófilo; Casas-Cabanas, Montse

    2015-04-15

    Na2Ti3O7 is considered a promising negative electrode for Na-ion batteries; however, poor capacity retention has been reported and the stability of the solid-electrolyte interphase (SEI) could be one of the main actors of this underperformance. The composition and evolution of the SEI in Na2Ti3O7 electrodes is hereby studied by means of X-ray photoelectron spectroscopy (XPS). To overcome typical XPS limitations in the photoelectron energy assignments, the analysis of the Auger parameter is here proposed for the first time in battery materials characterization. We have found that the electrode/electrolyte interface formed upon discharge, mostly composed by carbonates and semicarbonates (Na2CO3, NaCO3R), fluorides (NaF), chlorides (NaCl) and poly(ethylene oxide)s, is unstable upon electrochemical cycling. Additionally, solid state nuclear magnetic resonance (NMR) studies prove the reaction of the polyvinylidene difluoride (PVdF) binder with sodium. The powerful approach used in this work, namely Auger parameter study, enables us to correctly determine the composition of the electrode surface layer without any interference from surface charging or absolute binding energy calibration effects. As a result, the suitability for Na-ion batteries of binders and electrolytes widely used for Li-ion batteries is questioned here.

  14. Room-temperature solution-processed and metal oxide-free nano-composite for the flexible transparent bottom electrode of perovskite solar cells.

    PubMed

    Lu, Haifei; Sun, Jingsong; Zhang, Hong; Lu, Shunmian; Choy, Wallace C H

    2016-03-21

    The exploration of low-temperature and solution-processed charge transporting and collecting layers can promote the development of low-cost and large-scale perovskite solar cells (PVSCs) through an all solution process. Here, we propose a room-temperature solution-processed and metal oxide-free nano-composite composed of a silver nano-network and graphene oxide (GO) flawless film for the transparent bottom electrode of a PVSC. Our experimental results show that the amount of GO flakes play a critical role in forming the flawless anti-corrosive barrier in the silver nano-network through a self-assembly approach under ambient atmosphere, which can effectively prevent the penetration of liquid or gaseous halides and their corrosion against the silver nano-network underneath. Importantly, we simultaneously achieve good work function alignment and surface wetting properties for a practical bottom electrode by controlling the degree of reduction of GO flakes. Finally, flexible PVSC adopting the room-temperature and solution-processed nano-composite as the flexible transparent bottom electrode has been demonstrated on a polyethylene terephthalate (PET) substrate. As a consequence, the demonstration of our room-temperature solution-processed and metal oxide-free flexible transparent bottom electrode will contribute to the emerging large-area flexible PVSC technologies.

  15. Performance of glucose/O2 enzymatic fuel cell based on supporting electrodes over-coated by polymer-nanogold particle composite with entrapped enzymes

    NASA Astrophysics Data System (ADS)

    Huo, W. S.; Zeng, H.; Yang, Y.; Zhang, Y. H.

    2017-03-01

    Enzymatic electrodes over-coated by thin film of nano-composite made up of polymer and functionalized nano-gold particle was prepared. Glucose/O2 membrane-free enzymatic fuel cell based on nano-composite based electrodes with incorporated glucose oxidase and laccase was assembled. This enzymatic fuel cell exhibited high energy out-put density even when applied in human serum. Catalytic cycle involved in enzymatic fuel cell was limited by oxidation of glucose occurred on bioanode resulting from impact of sophisticated interaction between active site in glucose oxidase and nano-gold particle on configuration of redox center of enzyme molecule which crippled catalytic efficiency of redox protein.

  16. Enhancing Optical Out-Coupling of Organic Light-Emitting Devices with Nanostructured Composite Electrodes Consisting of Indium Tin Oxide Nanomesh and Conducting Polymer.

    PubMed

    Chen, Chien-Yu; Lee, Wei-Kai; Chen, Yi-Jiun; Lu, Chun-Yang; Lin, Hoang Yan; Wu, Chung-Chih

    2015-09-02

    A nanostructured composite electrode consisting of a high-index indium-tin-oxide nanomesh and low-index high-conductivity conducting polymer effectively enhances coupling of internal radiation of organic light-emitting devices into their substrates. When combining this internal extraction structure and the external extraction scheme, a very high external quantum efficiency of nearly 62% is achieved with a green phosphorescent device.

  17. Hydrogen peroxide biosensor based on gold nanoparticles/thionine/gold nanoparticles/multi-walled carbon nanotubes-chitosans composite film-modified electrode

    NASA Astrophysics Data System (ADS)

    Li, Shenfeng; Zhu, Xiaoying; Zhang, Wei; Xie, Guoming; Feng, Wenli

    2012-01-01

    In this paper, an amperometric electrochemical biosensor for the detection of hydrogen peroxide (H2O2), based on gold nanoparticles (GNPs)/thionine (Thi)/GNPs/multi-walled carbon nanotubes (MWCNTs)-chitosans (Chits) composite film was developed. MWCNTs-Chits homogeneous composite was first dispersed in acetic acid solution and then the GNPs were in situ synthesized at the composite. The mixture was dripped on the glassy carbon electrode (GCE) and then the Thi was deposited by electropolymerization by Au-S or Au-N covalent bond effect and electrostatic adsorption effect as an electron transfer mediator. Finally, the mixture of GNPs and horseradish peroxidase (HRP) was assembled onto the modified electrode by covalent bond. The electrochemical behavior of the modified electrode was investigated by scanning electron microscope, cyclic voltammetry and chronoamperometry. This study introduces the in situ-synthesized GNPs on the other surface of the modified materials in H2O2 detection. The linear response range of the biosensor to H2O2 concentration was from 5 × 10-7 mol L-1 to 1.5 × 10-3 mol L-1 with a detection limit of 3.75 × 10-8 mol L-1 (based on S/N = 3).

  18. Effects of Electrodeposition Mode and Deposition Cycle on the Electrochemical Performance of MnO2-NiO Composite Electrodes for High-Energy-Density Supercapacitors

    PubMed Central

    Rusi; Majid, S. R.

    2016-01-01

    Nanostructured network-like MnO2-NiO composite electrodes were electrodeposited onto stainless steel substrates via different electrodeposition modes, such as chronopotentiometry, chronoamperometry, and cyclic voltammetry, and then subjected to heat treatment at 300°C for metal oxide conversion. X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy were used to study the crystalline natures and morphologies of the deposited films. The electrochemical properties were investigated using cyclic voltammetry and charge/discharge tests. The results revealed that the electrochemical performance of the as-obtained composite electrodes depended on the electrodeposition mode. The electrochemical properties of MnO2-NiO composite electrodes prepared using cyclic voltammetry exhibited the highest capacitance values and were most influenced by the deposition cycle number. The optimum specific capacitance was 3509 Fg−1 with energy and power densities of 1322 Wh kg−1 and 110.5 kW kg−1, respectively, at a current density of 20 Ag−1 in a mixed KOH/K3Fe(CN)6 electrolyte. PMID:27182595

  19. Trace level voltammetric determination of lead and cadmium in sediment pore water by a bismuth-oxychloride particle-multiwalled carbon nanotube composite modified glassy carbon electrode.

    PubMed

    Cerovac, Sandra; Guzsvány, Valéria; Kónya, Zoltán; Ashrafi, Amir M; Švancara, Ivan; Rončević, Srđan; Kukovecz, Ákos; Dalmacija, Božo; Vytřas, Karel

    2015-03-01

    Two multiwalled carbon nanotubes-based composites modified with bismuth and bismuth-oxychloride particles were synthesized and attached to the glassy carbon electrode substrate. The resultant configurations, Bi/MWCNT-GCE and BiOCl/MWNT-GCE, were then characterized with respect to their physicochemical properties and electroanalytical performance in combination with square-wave anodic stripping voltammetry (SWASV). Further, some key experimental conditions and instrumental parameters were optimized; namely: the supporting electrolyte composition, accumulation potential and time, together with the parameters of the SWV-ramp. The respective method with both electrode configurations has then been examined for the trace level determination of Pb(2+) and Cd(2+) ions and the results compared to those obtained with classical bismuth-film modified GCE. The different intensities of analytical signals obtained at the three electrodes for Pb(2+) and Cd(2+) vs. the saturated calomel reference electrode had indicated that the nature of the modifiers and the choice of the supporting electrolyte influenced significantly the corresponding stripping signals. The most promising procedure involved the BiOCl/MWCNT-GCE and the acetate buffer (pH 4.0) offering limits of determination of 4.0 μg L(-1) Cd(2+) and 1.9 μg L(-1) Pb(2+) when accumulating for 120 s at a potential of -1.20 V vs. ref. The BiOCl/MWCNT electrode was tested for the determination of target ions in the pore water of a selected sediment sample and the results agreed well with those obtained by graphite furnace atomic absorption spectrometry.

  20. Novel lead-graphene and lead-graphite metallic composite materials for possible applications as positive electrode grid in lead-acid battery

    NASA Astrophysics Data System (ADS)

    Yolshina, L. A.; Yolshina, V. A.; Yolshin, A. N.; Plaksin, S. V.

    2015-03-01

    Novel lead-graphene and lead-graphite metallic composites which melt at temperature of the melting point of lead were investigated as possible positive current collectors for lead acid batteries in sulfuric acid solution. Scanning electron microscopy, Raman spectroscopy, difference scanning calorimetry, cyclic voltammetry and prolonged corrosion tests were employed to characterize the effect of the newly proposed lead-carbon metallic composites on the structure and electrochemical properties of positive grid material. Both lead-graphene and lead-graphite metallic composite materials show the similar electrochemical characteristics to metallic lead in the voltage range where the positive electrodes of lead acid batteries operate. It has been shown that carbon both as graphene and graphite does not participate in the electrochemical process but improve corrosion and electrochemical characteristics of both metallic composite materials. No products of interaction of lead with sulfuric acid were formed on the surface of graphene and graphite so as it was not found additional peaks of carbon discharge on voltammograms which could be attributed to the carbon. Graphene inclusions in lead prevent formation of leady oxide nanocrystals which deteriorate discharge characteristics of positive electrode of LAB. Both lead-graphene alloy and lead-graphite metallic composite proved excellent electrochemical and corrosion behavior and can be used as positive grids in lead acid batteries of new generation.

  1. Composite metal-hydrogen electrodes for metal-hydrogen batteries. Final report, October 1, 1993--April 15, 1997

    SciTech Connect

    Ruckman, M.W.; Strongin, M.; Weismann, H.

    1997-04-01

    The purpose of this project is to develop and conduct a feasibility study of metallic thin films (multilayered and alloy composition) produced by advanced sputtering techniques for use as anodes in Ni-metal hydrogen batteries that would be deposited as distinct anode, electrolyte and cathode layers in thin film devices. The materials could also be incorporated in secondary consumer batteries (i.e. type AF(4/3 or 4/5)) which use electrodes in the form of tapes. The project was based on pioneering studies of hydrogen uptake by ultra-thin Pd-capped Nb films, these studies suggested that materials with metal-hydrogen ratios exceeding those of commercially available metal hydride materials and fast hydrogen charging and discharging kinetics could be produced. The project initially concentrated on gas phase and electrochemical studies of Pd-capped niobium films in laboratory-scale NiMH cells. This extended the pioneering work to the wet electrochemical environment of NiMH batteries and exploited advanced synchrotron radiation techniques not available during the earlier work to conduct in-situ studies of such materials during hydrogen charging and discharging. Although batteries with fast charging kinetics and hydrogen-metal ratios approaching unity could be fabricated, it was found that oxidation, cracking and corrosion in aqueous solutions made pure Nb films and multilayers poor candidates for battery application. The project emphasis shifted to alloy films based on known elemental materials used for NiMH batteries. Although commercial NiMH anode materials contain many metals, it was found that 0.24 {mu}m thick sputtered Zr-Ni films cycled at least 50 times with charging efficiencies exceeding 95% and [H]/[M] ratios of 0.7-1.0. Multilayered or thicker Zr-Ni films could be candidates for a thin film NiMH battery that may have practical applications as an integrated power source for modern electronic devices.

  2. Study on dielectric and piezoelectric properties of 0.7 Pb(Mg1/3Nb2/3)O3-0.3 PbTiO3 single crystal with nano-patterned composite electrode

    NASA Astrophysics Data System (ADS)

    Chang, Wei-Yi; Huang, Wenbin; Bagal, Abhijeet; Chang, Chih-Hao; Tian, Jian; Han, Pengdi; Jiang, Xiaoning

    2013-09-01

    Effect of nano-patterned composite electrode and backswitching poling technique on dielectric and piezoelectric properties of 0.7 Pb(Mg1/3Nb2/3)O3-0.3 PbTiO3 was studied in this paper. Composite electrode consists of Mn nano-patterns with pitch size of 200 nm, and a blanket layer of Ti/Au was fabricated using a nanolithography based lift-off process, heat treatment, and metal film sputtering. Composite electrode and backswitching poling resulted in 27% increase of d33 and 25% increase of dielectric constant, and we believe that this is attributed to regularly defined nano-domains and irreversible rhombohedral to monoclinic phase transition in crystal. The results indicate that nano-patterned composite electrode and backswitching poling has a great potential in domain engineering of relaxor single crystals for advanced devices.

  3. Study on dielectric and piezoelectric properties of 0.7 Pb(Mg1/3Nb2/3)O3-0.3 PbTiO3 single crystal with nano-patterned composite electrode.

    PubMed

    Chang, Wei-Yi; Huang, Wenbin; Bagal, Abhijeet; Chang, Chih-Hao; Tian, Jian; Han, Pengdi; Jiang, Xiaoning

    2013-09-21

    Effect of nano-patterned composite electrode and backswitching poling technique on dielectric and piezoelectric properties of 0.7 Pb(Mg1/3Nb2/3)O3-0.3 PbTiO3 was studied in this paper. Composite electrode consists of Mn nano-patterns with pitch size of 200 nm, and a blanket layer of Ti/Au was fabricated using a nanolithography based lift-off process, heat treatment, and metal film sputtering. Composite electrode and backswitching poling resulted in 27% increase of d33 and 25% increase of dielectric constant, and we believe that this is attributed to regularly defined nano-domains and irreversible rhombohedral to monoclinic phase transition in crystal. The results indicate that nano-patterned composite electrode and backswitching poling has a great potential in domain engineering of relaxor single crystals for advanced devices.

  4. Vanadium Oxide Electrochemical Capacitors: An Investigation into Aqueous Capacitive Degradation, Alternate Electrolyte-Solvent Systems, Whole Cell Performance and Graphene Oxide Composite Electrodes

    NASA Astrophysics Data System (ADS)

    Engstrom, Allison Michelle

    Vanadium oxide has emerged as a potential electrochemical capacitor material due to its attractive pseudocapacitive performance; however, it is known to suffer from capacitive degradation upon sustained cycling. In this work, the electrochemical cycling behavior of anodically electrodeposited vanadium oxide films with various surface treatments in aqueous solutions is investigated at different pH. Quantitative compositional analysis and morphological studies provide additional insight into the mechanism responsible for capacitive degradation. Furthermore, the capacitance and impedance behavior of vanadium oxide electrochemical capacitor electrodes is compared for both aqueous and nonaqueous electrolyte-solvent systems. Alkali metal chloride and bromide electrolytes were studied in aqueous systems, and nonaqueous systems containing alkali metal bromides were studied in polar aprotic propylene carbonate (PC) or dimethyl sulfoxide (DMSO) solvents. The preferred aqueous and nonaqueous systems identified in the half-cell studies were utilized in symmetric vanadium oxide whole-cells. An aqueous system utilizing a 3.0 M NaCl electrolyte at pH 3.0 exhibited an excellent 96% capacitance retention over 3000 cycles at 10 mV s-1. An equivalent system tested at 500 mV s-1 displayed an increase in capacitance over the first several thousands of cycles, and eventually stabilized over 50,000 cycles. Electrodes cycled in nonaqueous 1.0 M LiBr in PC exhibited mostly non-capacitive charge-storage, and electrodes cycled in LiBr-DMSO exhibited a gradual capacitive decay over 10,000 cycles at 500 mV s-1. Morphological and compositional analyses, as well as electrochemical impedance modeling, provide additional insight into the cause of the cycing behavior. Lastly, reduced graphene oxide and vanadium oxide nanowire composites have been successfully synthesized using electrophoretic deposition for electrochemical capacitor electrodes. The composite material was found to perform with a

  5. Li2Ni(0.5)Mn(0.5)SnO4/C: A Novel Hybrid Composite Electrode for High Rate Applications.

    PubMed

    Vellaisamy, Mani; Nallathamby, Kalaiselvi

    2015-09-08

    A novel Li2Ni(0.5)Mn(0.5)SnO4/C composite electrode, existing as a hybrid consisting of monoclinic Li2SnO3 and layered LiNi(0.5)Mn(0.5)O2, has been identified and validated for high capacity and high rate lithium battery applications. Of the components, LiNi(0.5)Mn(0.5)O2 upon discharge forms the corresponding dilithium oxide, viz., Li2Ni(0.5)Mn(0.5)O2, and facilitates the progressive electrochemical performance of the composite electrode. Similarly, Li2SnO3 upon discharge forms Li2O and SnO2, wherein the unacceptable volume expansion related issues of SnO2 are addressed by the buffering activity of Li2O phase. A combination of alloying/dealloying, conversion, and redox mechanism is responsible for the excellent electrochemical behavior of Li2Ni(0.5)Mn(0.5)SnO4/C electrode. With this newer formulation of dilithium stannate composite, a superior capacity of >3000 mAh g(-1) at 100 mA g(-1) current density has been demonstrated. The study opens up a newer gateway for the entry of Li2SnO3·LiM1M2O2 hybrid formulations for exploitation up to 1 A g(-1) rate, thus ensuring the sustainable development of potential electrode materials for high rate applications.

  6. Sputtering TiO2 on LiCoO2 composite electrodes as a simple and effective coating to enhance high-voltage cathode performance

    NASA Astrophysics Data System (ADS)

    Zhou, Aijun; Lu, Yanting; Wang, Qingji; Xu, Jin; Wang, Weihang; Dai, Xinyi; Li, Jingze

    2017-04-01

    Surface coating is a key strategy in lithium-ion battery technologies to achieve a high and stable battery performance. Increasing the operation voltage is a direct way to increase the energy density of the battery. In this work, TiO2 is directly sputtered on as-fabricated LiCoO2 composite electrodes, enabling a controllable oxide coating on the topmost of the electrode. With an optimum coating, the discharge capacity is able to reach 160 mAh g-1 (86.5% retention) after 100 cycles within 3.0-4.5 V at 1 C, which is increased by 40% compared to that of the bare electrode. The high-voltage rate capability of LiCoO2 is also remarkably enhanced after TiO2-coating as reflected by the much larger capacity at 10 C (109 vs. 74 mAh g-1). The artificially introduced oxide coating is believed to make the LiCoO2 electrode more resistant to interfacial side reactions at high voltage and thus minimizes the irreversible loss of the active material upon long cycling. The TiO2 coating layer is also possible to partially react with the decomposition product of electrolyte (e.g. HF) and form a more stable and conductive interphase containing TiFx, which is responsible for the improvement of the rate capability.

  7. Performance of the “SiO”-carbon composite-negative electrodes for high-capacity lithium-ion batteries; prototype 14500 batteries

    NASA Astrophysics Data System (ADS)

    Yamada, Masayuki; Uchitomi, Kazutaka; Ueda, Atsushi; Matsumoto, Kazunobu; Ohzuku, Tsutomu

    2013-03-01

    Prototype 14500 batteries (14 mm dia. and 50 mm hgt.; AA size) consisted of the “SiO”-carbon composite-negative and LiCo1/3Ni1/3Mn1/3O2/LiCoO2 (7/3 by weight)-positive electrodes were designed, fabricated and examined in voltage ranging from 2.5 to 4.2 V at -20, -10, 0, and +23 °C. The batteries were stored and delivered 1 Ah at 200 mA and 0.96 Ah at 2 A, and the capacity remained after 300 cycles at 23 °C was 0.7 Ah. Abuse tests, such as overcharging to 12 V, nail penetration, and heating of fully charged batteries in an oven at 150 °C, were also carried out and shown that the batteries showed neither smoke nor fire for all the tests examined. The battery performance was compared to that of conventional batteries with graphite-negative electrodes in the same size and the characteristic features of the lithium-ion batteries with the SiO-carbon composite-negative electrodes were discussed from the experimental results.

  8. Mesoporous composite nickel cobalt oxide/graphene oxide synthesized via a template-assistant co-precipitation route as electrode material for supercapacitors

    NASA Astrophysics Data System (ADS)

    Xu, Yanjie; Wang, Lincai; Cao, Peiqi; Cai, Chuanlin; Fu, Yanbao; Ma, Xiaohua

    2016-02-01

    A simple co-precipitation method utilizing SDS (sodium dodecyl sulfate) as template and ammonia as precipitant is successfully employed to synthesize nickel cobalt oxide/graphene oxide (NiCo2O4/GO) composite. The as-prepared composite (NCG-10) exhibits a high capacitance of 1211.25 F g-1, 687 F g-1 at the current density of 1 A g-1, 10 A g-1 and good cycling ability which renders NCG-10 as promising electrode material for supercapacitors. An asymmetric supercapacitor (ASC) (full button cell) has been constructed with NCG-10 as positive electrode and lab-made reduced graphene oxide (rGO) as negative electrode. The fabricated NCG-10//rGO with an extended stable operational voltage of 1.6 V can deliver a high specific capacitance of 144.45 F g-1 at a current density of 1 A g-1. The as-prepared NCG-10//rGO demonstrates remarkable energy density (51.36 W h kg-1 at 1 A g-1), high power density (50 kW kg-1 at 20 A g-1). The retention of capacitance is 88.6% at the current density of 8 A g-1 after 2000 cycles. The enhanced capacitive performance can be attributed to the improved specific surface area and 3D open area of NCG-10 generated by the pores and channels with the substantial function of SDS.

  9. Electrochemical characterization of MnO2-based composite in the presence of salt-in-water and water-in-salt electrolytes as electrode for electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Gambou-Bosca, Axel; Bélanger, Daniel

    2016-09-01

    The effect of the electrolyte on the electrochemical utilization of manganese dioxide as active material for electrochemical capacitor was studied by cyclic voltammetry and electrochemical impedance spectroscopy. MnO2-based composite electrodes were characterized in salt-in-water (0.65 M K2SO4, 5 M LiNO3, 0.5 M LiNO3 and 0.5 M Ca(NO3)2) and water-in-salt (5 M LiTFSI (lithium bis-trifluoromethanesulfonimide)) electrolytes. Firstly, no effect of the cation valence on the specific capacitance was observed as similar values were measured in 0.5 M LiNO3 and 0.5 M Ca(NO3)2 aqueous solutions at both low and high scan rate, when a MnO2-based composite electrode was cycled in the pseudocapacitive potential region. Secondly, it was found that in 5 M LiTFSI, a MnO2 electrode is characterized by an extended potential stability window of about 1.4 V and exhibits a high specific capacitance of 239 F g-1 per active material mass at a scan rate of 2 mV s-1. However due to the low ionic conductivity of this solution, the rate capability is limited at high scan rate.

  10. Electrochemical behavior and voltammetric determination of acetaminophen based on glassy carbon electrodes modified with poly(4-aminobenzoic acid)/electrochemically reduced graphene oxide composite films.

    PubMed

    Zhu, Wencai; Huang, Hui; Gao, Xiaochun; Ma, Houyi

    2014-12-01

    Poly(4-aminobenzoic acid)/electrochemically reduced graphene oxide composite film modified glassy carbon electrodes (4-ABA/ERGO/GCEs) were fabricated by a two-step electrochemical method. The electrochemical behavior of acetaminophen at the modified electrode was investigated by means of cyclic voltammetry. The results indicated that 4-ABA/ERGO composite films possessed excellent electrocatalytic activity towards the oxidation of acetaminophen. The electrochemical reaction of acetaminophen at 4-ABA/ERGO/GCE is proved to be a surface-controlled process involving the same number of protons and electrons. The voltammetric determination of acetaminophen performed with the 4-ABA/ERGO modified electrode presents a good linearity in the range of 0.1-65 μM with a low detection limit of 0.01 μM (S/N=3). In the case of using the 4-ABA/ERGO/GCE, acetaminophen and dopamine can be simultaneously determined without mutual interference. Furthermore, the 4-ABA/ERGO/GCE has good reproducibility and stability, and can be used to determine acetaminophen in tablets.

  11. Application of graphene-ionic liquid-chitosan composite-modified carbon molecular wire electrode for the sensitive determination of adenosine-5'-monophosphate.

    PubMed

    Shi, Fan; Gong, Shixing; Xu, Li; Zhu, Huanhuan; Sun, Zhenfan; Sun, Wei

    2013-12-01

    In this paper, a graphene (GR) ionic liquid (IL) 1-octyl-3-methylimidazolium hexafluorophosphate and chitosan composite-modified carbon molecular wire electrode (CMWE) was fabricated by a drop-casting method and further applied to the sensitive electrochemical detection of adenosine-5'-monophosphate (AMP). CMWE was prepared with diphenylacetylene (DPA) as the modifier and the binder. The properties of modified electrode were examined by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical behaviors of AMP was carefully investigated with enhanced responses appeared, which was due to the presence of GR-IL composite on the electrode surface with excellent electrocatalytic ability. A well-defined oxidation peak of AMP appeared at 1.314 V and the electrochemical parameters were calculated by electrochemical methods. Under the selected conditions, the oxidation peak current of AMP was proportional to its concentration in the range from 0.01 μM to 80.0 μM with the detection limit as 3.42 nM (3σ) by differential pulse voltammetry. The proposed method exhibited good selectivity and was applied to the detection of vidarabine monophosphate injection samples with satisfactory results.

  12. Highly efficient dye-sensitized solar cells achieved through using Pt-free Nb2O5/C composite counter electrode and iodide-free redox couples

    NASA Astrophysics Data System (ADS)

    Li, Ling; Lu, Qi; Li, Wenyan; Li, Xiaowei; Hagfeldt, Anders; Zhang, Wenming; Wu, Mingxing

    2016-03-01

    To improve the catalytic activity of Nb2O5, a composite Nb2O5/C (Nb2O5 imbedded in carbon support) is synthesized with a simple in situ method and then introduced the composite into dye-sensitized solar cells (DSCs) as a counter electrode (CE) catalyst. Based on the analysis of the cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel-polarization curve measurements, the catalytic activity of the Nb2O5/C composite for the regeneration of iodide-free redox couples of polysulfide (T2/T-) and cobalt complex (Co3+/2+) is indeed enhanced significantly as compared with pure Nb2O5, because the composite electrode eliminates the particle aggregation and forms a mesoporous network structure with large pore size. The T2/T- electrolyte based DSCs with Nb2O5/C CE yields a high power conversion efficiency (PCE) of 6.11%, generating a great improvement of 63.8% as compared to the Pt CE based DSCs. In addition, the Nb2O5/C exhibits higher catalytic activity than Pt for regenerating the Co3+/2+ redox couple and the DSCs using Nb2O5/C CE shows a high PCE of 9.86%.

  13. Graphene/poly(ethylene-co-vinyl acetate) composite electrode fabricated by melt compounding for capillary electrophoretic determination of flavones in Cacumen platycladi.

    PubMed

    Sheng, Shijun; Liu, Shuang; Zhang, Luyan; Chen, Gang

    2013-02-01

    In this report, a graphene/poly(ethylene-co-vinyl acetate) composite electrode was fabricated by melt compounding for the amperometric detection of capillary electrophoresis. The composite electrode was fabricated by packing a mixture of graphene and melted poly(ethylene-co-vinyl acetate) in a piece of fused silica capillary under heat. The structure of the composite was investigated by scanning electron microscopy and Fourier transform infrared spectroscopy. The results indicated that graphene sheets were well dispersed in the composite to form an interconnected conducting network. The performance of this unique graphene-based detector has been demonstrated by separating and detecting rutin, quercitrin, kaempferol, and quercetin in Cacumen platycladi in combination with capillary electrophoresis. The four flavones have been well separated within 9 min in a 50-cm-long capillary at a separation voltage of 12 kV using a 50 mM sodium borate buffer (pH 9.2). The graphene-based detector offered significantly lower operating potentials, substantially enhanced signal-to-noise characteristics, lower expense of operation, high resistance to surface fouling, and enhanced stability. It showed long-term stability and repeatability with relative standard deviations of <5% for the peak current (n = 15).

  14. Low-Temperature All-Solution-Processed Transparent Silver Nanowire-Polymer/AZO Nanoparticles Composite Electrodes for Efficient ITO-Free Polymer Solar Cells.

    PubMed

    Zhang, Xiaoqin; Wu, Jiang; Wang, Jiantai; Yang, Qingqing; Zhang, Baohua; Xie, Zhiyuan

    2016-12-21

    We present a kind of all-solution-processed transparent conductive film comprising of silver nanowire (AgNW), polyvinyl butyral (PVB), and Al-doped ZnO nanoparticles (AZO NPs) composite (APA) by layer-by-layer blade-coating on glass substrate at low temperature. This kind of transparent APA film exhibits high transmittance at a wide range of 400-700 nm. The sheet resistance of the APA film can be as low as 21 Ω sq(-1) with transmittance over 94% at 550 nm. The introduction of PVB significantly improves the APA composite adhesion to glass substrate. The overlaid coating of AZO NPs not only reduces the sheet resistance but also improves the ambient and thermal stability of the APA film. This highly conductive and transparent APA film on glass substrate is employed as the bottom electrode to fabricate high-efficiency polymer solar cells (PSCs). A power conversion efficiency of 8.98% is achieved for the PBDTTT-EFT:PC71BM PSCs employing the APA composite as transparent bottom electrode, close to 9.54% of the control device fabricated on the commercial indium tin oxide substrate. As it can be easily prepared with all-solution-processed blade-coating method at low temperature, this kind of AgNW-based composite film is promising to integrate with roll-to-roll manufacturing of flexible PSCs.

  15. Direct electrochemistry of glucose oxidase immobilized on NdPO4 nanoparticles/chitosan composite film on glassy carbon electrodes and its biosensing application.

    PubMed

    Sheng, Qinglin; Luo, Kai; Li, Lei; Zheng, Jianbin

    2009-02-01

    The direct electrochemistry of glucose oxidase (GOx) immobilized on a composite matrix based on chitosan (CHIT) and NdPO(4) nanoparticles (NPs) underlying on glassy carbon electrode (GCE) was achieved. The cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the modified electrode. In deaerated buffer solutions, the cyclic voltammetry of the composite films of GOx/NdPO(4) NPs/CHIT showed a pair of well-behaved redox peaks that are assigned to the redox reaction of GOx, confirming the effective immobilization of GOx on the composite film. The electron transfer rate constant was estimated to be 5.0 s(-1). The linear dynamic range for the detection of glucose was 0.15-10 mM with a correlation coefficient of 0.999 and the detection limit was estimated at about 0.08 mM (S/N=3). The calculated apparent Michaelis-Menten constant was 2.5 mM, which suggested a high affinity of the enzyme-substrate. The immobilized GOx in the NdPO(4) NPs/CHIT composite film retained its bioactivity. Furthermore, the method presented here can be easily extended to immobilize and obtain the direct electrochemistry of other redox enzymes or proteins.

  16. Ionic Liquid-Derived Imidazolium Cation Linkers for the Layer-by-Layer Assembly of Polyoxometalate-MWCNT Composite Electrodes with High Power Capability.

    PubMed

    Genovese, Matthew; Lian, Keryn

    2016-07-27

    Imidazolium cations derived from ionic liquids were demonstrated as effective linker molecules for the layer-by-layer (LbL) deposition of polyoxometalates (POMs) to increase the charge storage of multi-walled carbon nanotube (MWCNT) electrodes. MWCNTs modified with GeMo12O40(4-) (GeMo12) via an imidazolium cation linker demonstrated highly reversible redox reactions and a capacitance of 84 F cm(-3), close to 4 times larger than bare CNT. Compared to CNT-GeMo12 composites fabricated with a conventional polyelectrolyte linker poly(diallyldimethylammonium chloride), (PDDA), the imidazolium cations resulted in lower POM loading, but higher conductivity and in turn superior performance at fast charge-discharge conditions. A polymerized imidazolium linker (PIL) was also synthesized based on the ethyl-vinyl-imidazolium monomer. CNT-GeMo12 composites fabricated with this PIL achieved high POM loading comparable to PDDA, while still maintaining the good conductivity and high rate capabilities shown by the monomer imidazolium units. The high conductivity imparted by the PIL is especially valuable for the fabrication of multilayer POM composites. Dual-layer GeMo12 O40(4-)-SiMo12O40(4-) (GeMo12-SiMo12) electrodes built with this PIL demonstrated a combined contribution of the individual POMs resulting in a capacitance of 191 F cm(-3), over nine times larger than bare MWCNT. The PIL dual layer composites also maintained 72% of this capacitance at a fast rate of 2 V s(-1), compared to just over 50% retention for similar electrodes fabricated with PDDA.

  17. Role of heat on the development of electrochemical sensors on bare and modified Co3O4/CuO composite nanopowder carbon paste electrodes.

    PubMed

    Kumar, Mohan; Kumara Swamy, B E

    2016-01-01

    The Co3O4/CuO composite nanopowder (NP) was synthesized by a mechanochemical method and characterized by using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The synthesized Co3O4/CuO NP was used as a modified carbon paste electrode (MCPE) and further the bare carbon paste and Co3O4/CuO NP modified carbon paste was heated at different temperatures (100, 150, 200 and 250 °C) for 10 min. The Co3O4/CuO NP MCPE was used to study the consequences of scan rate and dopamine concentration. Furthermore the preheated modified electrodes were used to study the electrochemical response to dopamine (DA), ascorbic acid (AA) and uric acid (UA).

  18. Room-temperature solution-processed and metal oxide-free nano-composite for the flexible transparent bottom electrode of perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Lu, Haifei; Sun, Jingsong; Zhang, Hong; Lu, Shunmian; Choy, Wallace C. H.

    2016-03-01

    The exploration of low-temperature and solution-processed charge transporting and collecting layers can promote the development of low-cost and large-scale perovskite solar cells (PVSCs) through an all solution process. Here, we propose a room-temperature solution-processed and metal oxide-free nano-composite composed of a silver nano-network and graphene oxide (GO) flawless film for the transparent bottom electrode of a PVSC. Our experimental results show that the amount of GO flakes play a critical role in forming the flawless anti-corrosive barrier in the silver nano-network through a self-assembly approach under ambient atmosphere, which can effectively prevent the penetration of liquid or gaseous halides and their corrosion against the silver nano-network underneath. Importantly, we simultaneously achieve good work function alignment and surface wetting properties for a practical bottom electrode by controlling the degree of reduction of GO flakes. Finally, flexible PVSC adopting the room-temperature and solution-processed nano-composite as the flexible transparent bottom electrode has been demonstrated on a polyethylene terephthalate (PET) substrate. As a consequence, the demonstration of our room-temperature solution-processed and metal oxide-free flexible transparent bottom electrode will contribute to the emerging large-area flexible PVSC technologies.The exploration of low-temperature and solution-processed charge transporting and collecting layers can promote the development of low-cost and large-scale perovskite solar cells (PVSCs) through an all solution process. Here, we propose a room-temperature solution-processed and metal oxide-free nano-composite composed of a silver nano-network and graphene oxide (GO) flawless film for the transparent bottom electrode of a PVSC. Our experimental results show that the amount of GO flakes play a critical role in forming the flawless anti-corrosive barrier in the silver nano-network through a self

  19. Composite films of oxidized multiwall carbon nanotube and poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) as a contact electrode for transistor and inverter devices.

    PubMed

    Yun, Dong-Jin; Rhee, Shi-Woo

    2012-02-01

    Composite films of multiwall carbon nanotube (MWNT)/poly(3,4-ethylenedioxythiophene) polymerized with poly(4-styrenesulfonate) (PEDOT:PSS) were prepared by spin-coating a mixture solution. The effect of the MWNT loading and the MWNT oxidation, with acid solution or ultraviolet (UV)-ozone treatment, on the film properties such as surface roughness, work function, surface energy, optical transparency and conductivity were studied. Also pentacene thin film transistors and inverters were made with these composite films as a contact metal and the device characteristics were measured. The oxidation of MWNT reduced the conductivity of MWNT/PEDOT:PSS composite film but increased the work function and transparency. UV-ozone treated MWNT/PEDOT:PSS composite film showed higher conductivity (14000 Ω/□) and work function (4.9 eV) than acid-oxidized MWNT/PEDOT:PSS composite film and showed better performance as a source/drain electrode in organic thin film transistor (OTFT) than other types of MWNT/PEDOT:PSS composite films. Hole injection barrier of the UV-ozone treated MWNT/PEDOT:PSS composite film with pentacene was significantly lower than any other films because of the higher work function.

  20. Physical and electrochemical properties of supercapacitor composite electrodes prepared from biomass carbon and carbon from green petroleum coke

    NASA Astrophysics Data System (ADS)

    Awitdrus, Deraman, M.; Talib, I. A.; Farma, R.; Omar, R.; Ishak, M. M.; Taer, E.; Dolah, B. N. M.; Basri, N. H.; Nor, N. S. M.

    2015-04-01

    The green monoliths (GMs) were prepared from the mixtures of pre-carbonized fibers of oil palm empty fruit bunches (or self-adhesive carbon grains (SACG)) and green petroleum coke (GPC) with the mixing ratio of 0, 10, 30, 50 and 70 % GPC, respectively. The GMs were carbonized in N2 environment at 800°C to produce carbon monoliths (CM00, CM10, CM30, CM50 and CM70). The CMs were CO2 activated at 800°C for 1 hour to produced activated carbon monolith electrodes (ACM00, ACM10, ACM30, ACM50 and ACM70). For each percentage of GPC, three duplicate symmetrical supercapacitor cells were fabricated using these activated carbon monolith electrodes respectively, and the capacitive performance amongst the cells was compared and analyzed in order to observe the relationship between the capacitive performance and the physical properties (microstructure and porosity) of the ACMs electrodes containing varying percentage of GPC.

  1. Enhancing electrocatalytic performance of Sb-doped SnO ₂ electrode by compositing nitrogen-doped graphene nanosheets.

    PubMed

    Duan, Tigang; Wen, Qing; Chen, Ye; Zhou, Yiding; Duan, Ying

    2014-09-15

    An efficient Ti/Sb-SnO2 electrode modified with nitrogen-doped graphene nanosheets (NGNS) was successfully fabricated by the sol-gel and dip coating method. Compared with Ti/Sb-SnO2 electrode, the NGNS-modified electrode possesses smaller unite crystalline volume (71.11Å(3) vs. 71.32Å(3)), smaller electrical resistivity (13Ωm vs. 34Ωm), and lower charge transfer resistance (10.91Ω vs. 21.01Ω). The accelerated lifetime of Ti/Sb-SnO2-NGNS electrode is prolonged significantly, which is 4.45 times as long as that of Ti/Sb-SnO2 electrode. The results of X-ray photoelectron spectroscopy measurement and voltammetric charge analysis indicate that introducing NGNS into the active coating can increase more reaction active sites to enhance the electrocatalytic efficiency. The electrochemical dye decolorization analysis demonstrates that Ti/Sb-SnO2-NGNS presents efficient electrocatalytic performance for methylene blue and orange II decolorization. And its pseudo-first order kinetic rate constants for methylene blue and orange II decolorization are 36.6 and 44.0 min(-1), respectively, which are 6.0 and 7.1 times as efficient as those of Ti/Sb-SnO2, respectively. Considering the significant electrocatalytic activity and low resistivity of Ti/Sb-SnO2-NGNS electrode, the cost of wastewater treatment can be expected to be reduced obviously and the application prospect is broad.

  2. Fabrication methods for low impedance lithium polymer electrodes

    DOEpatents

    Chern, T.S.; MacFadden, K.O.; Johnson, S.L.

    1997-12-16

    A process is described for fabricating an electrolyte-electrode composite suitable for high energy alkali metal battery that includes mixing composite electrode materials with excess liquid, such as ethylene carbonate or propylene carbonate, to produce an initial formulation, and forming a shaped electrode therefrom. The excess liquid is then removed from the electrode to compact the electrode composite which can be further compacted by compression. The resulting electrode exhibits at least a 75% lower resistance.

  3. Fabrication methods for low impedance lithium polymer electrodes

    DOEpatents

    Chern, Terry Song-Hsing; MacFadden, Kenneth Orville; Johnson, Steven Lloyd

    1997-01-01

    A process for fabricating an electrolyte-electrode composite suitable for high energy alkali metal battery that includes mixing composite electrode materials with excess liquid, such as ethylene carbonate or propylene carbonate, to produce an initial formulation, and forming a shaped electrode therefrom. The excess liquid is then removed from the electrode to compact the electrode composite which can be further compacted by compression. The resulting electrode exhibits at least a 75% lower resistance.

  4. Trace analysis of Ponceau 4R in soft drinks using differential pulse stripping voltammetry at SWCNTs composite electrodes based on PEDOT:PSS derivatives.

    PubMed

    Wang, Zifei; Zhang, Hui; Wang, Zhipeng; Zhang, Jie; Duan, Xuemin; Xu, Jingkun; Wen, Yangping

    2015-08-01

    Ponceau 4R, an edible synthetic colorant used in drinks, syrups, and sweets, has been successfully detected using differential pulse voltammetry at a single-walled carbon nanotubes-modified composite electrode based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) and two derivatives thereof. The electrochemical parameters of three Ponceau 4R sensors, such as pH value, pre-concentration time, and scan rate, have been optimized, and their electrochemical performances have been compared. A poly(acrylate-modified 3,4-ethylenedioxythiophene-co-3,4-ethylenedioxythiophene):poly(styrene sulfonate)-single-walled carbon nanotubes-poly(vinyl alcohol)-modified electrode showed the best electrocatalytic activity, with the highest response current, lowest detection limit (1.8 nm), widest linear range (0.0055-110.6 μm), and best sensing stability. Additionally, the modified electrode has also been successfully employed for real sample analysis with soft drinks. Satisfactory results were obtained, demonstrating this to be an easy and effective approach for trace analysis of Ponceau 4R in food samples.

  5. An Amperometric Immunosensor Based on an Ionic Liquid and Single-Walled Carbon Nanotube Composite Electrode for Detection of Tetrodotoxin in Pufferfish.

    PubMed

    Zhang, Yun; Fan, Yuxia; Wu, Jian; Wang, Xichang; Liu, Yuan

    2016-09-14

    An amperometric immunosensor based on a composite electrode of single-walled carbon nanotubes and ionic liquid n-octylpyridinum afluorophosphate (SWCNT-ILE) was developed for the determination of tetrodotoxin (TTX). Compared with the glassy carbon electrode (GCE), the electrode combined advantages of carbon nanotubes and ionic liquid, which exhibited the excellent antifouling ability of p-nitrophenol (PNP) so that it remarkably improved the stability of the p-nitrophenyl phosphate-based sensor. Combining the enzyme-linked immune sorbent assay (ELISA) by alkaline phosphatase (AP) and magnetic particles immobilized with antigens, a real-time assay of tetrodotoxin was developed by amperometric immunosensors. Under the optimium condition, the developed sensor demonstrated a linear range of tetrodotoxin from 2 to 45 ng/mL with a low detection limit of 5 ng/mL. Furthermore, the amperometric immunosensor was applied to determine TTX in real samples and could be used as an effective and sensitive sensor for direct detection of tetrodotoxin within 20 min.

  6. Binderless Composite Electrode Monolith from Carbon Nanotube and Biomass Carbon Activated by H2 SO4 and CO2 Gas for Supercapacitor

    NASA Astrophysics Data System (ADS)

    Deraman, M.; Ishak, M. M.; Farma, R.; Awitdrus, Taer, E.; Talib, I. A.; Omar, R.

    2011-12-01

    Binderless composite electrodes in the monolithic form prepared from carbon nanotubes (CNTs) and self-adhesive carbon grains (SACG) from fibers of oil palm empty fruit bunch were studied as an electrode in a supercapacitor. The green monoliths (GMs) were prepared from three different types of precursors, SACG, SACG treated with 0.4 Molar H2 SO4 and mixture of SACG and 5% CNTs (by weight) treated with 0.4 Molar H2 SO4 , respectively. These GMs were carbonized at 600 ° C in N2 gas environment and activated by CO2 gas at 800 ° C for 1 hour to produce activated carbon monoliths (ACMs). The properties of the ACMs (density, porosity, microstructure, structure and electrical conductivity) were found affected by CNTs addition and acid treatment. The acid treatment did not improve the electrochemical behavior of the ACMs used as electrodes (specific capacitance, specific energy and specific power of the supercapacitor) in the supercapacitor cells but CNTs addition improves the equivalent series resistance of the cell.

  7. The counterintuitive impact of separator-electrolyte combinations on the cycle life of graphite-silicon composite electrodes

    NASA Astrophysics Data System (ADS)

    Schott, Tiphaine; Gómez-Cámer, Juan Luis; Bünzli, Christa; Novák, Petr; Trabesinger, Sigita

    2017-03-01

    Thin polymeric membranes such as Celgard are commonly used as separators in Li-ion batteries to ensure high volumetric energy density. Independently, for silicon-based electrodes fluoroethylene carbonate (FEC) is often added to the electrolyte to improve the cycling stability of the cell. Here we demonstrate that, counterintuitively, this separator-electrolyte combination negatively affects the performance of graphite-Si electrodes in half-cells. In a statistical evaluation of the cycling behavior of C-Si electrode cells with various separators and either with or without FEC addition, we show that by improving the solid electrolyte interphase on the silicon particles, FEC addition leads to inhomogeneous current distribution in the electrodes, therefore favoring lithium dendrite growth and leading to irreversible failure with Celgard. In contrast, self-recovery is observed with simple glass-fiber separators. Without FEC, neither dendrites nor failure are observed, but cells with Celgard suffer from poorer electrochemical performance, due to clogging by the thick polymeric layer formed using standard electrolytes, than cells with thicker and hydrophilic separators.

  8. Compositional analysis of passivating surface film formed on carbon electrode in organic electrolytic solution using in-situ spectroelectrochemical technique

    NASA Astrophysics Data System (ADS)

    Pyun, Su-Il

    1999-02-01

    In-situ spectroelectrochemical technique has been applied to investigate passivating surface film on porous carbon electrode and plasma enhanced chemical vapour deposited (PECVD) carbon film electrode in organic electrolytic solution consisting of ethylene carbonate (EC) and diethyl carbonate (DEC) solvent, and 1 M LiPF6 and LiAsF6. Water impurity with the concentration of 0 M, 0.02 M, 0.05 M, and 0.1 M H20 was added to 1 M LiPF6-EC/DEC solution. In-situ Fourier transform infra-red (FTIR) spectra of the surface film on both electrodes with the constituents of ROCO2Li, Li2CO3, and LixPFy suggested that the reduction of EC to ROCO2Li runs via a one-electron transfer pathway as a result of diffusion of water through the surface film, and then Li2CO3 formation proceeds simultaneously by the chemical reaction of ROCO2Li with water. From the measured potential dependence of the amount of the salt reduction products, it is suggested that the surface film formed in 1 M LiPF6EC/DEC solution gives a poorer passivity as compared with that formed in 1 M LiAsF6-EC/DEC solution, which is due to the considerable interference of LiPE6 salt reduction with the compact sedimentation of ROCO2Li on the electrode. In-situ FFIR spectra of the surface film showed that all the peak intensities of the three constituents significantly increase with increasing water content under application of the negative potentials with respect to open circuit potential (OCP). From these experimental results, the dependence of the passivity of the surface film on the carbon electrode on the water concentration of the electrolyte, as well as on the lithium salt type, was discussed in view of the salt and solvent reactivities.

  9. Electrochemical sensors for the simultaneous determination of zinc, cadmium and lead using a Nafion/ionic liquid/graphene composite modified screen-printed carbon electrode.

    PubMed

    Chaiyo, Sudkate; Mehmeti, Eda; Žagar, Kristina; Siangproh, Weena; Chailapakul, Orawon; Kalcher, Kurt

    2016-04-28

    A simple, low cost, and highly sensitive electrochemical sensor, based on a Nafion/ionic liquid/graphene composite modified screen-printed carbon electrode (N/IL/G/SPCE) was developed to determine zinc (Zn(II)), cadmium (Cd(II)), and lead (Pb(II)) simultaneously. This disposable electrode shows excellent conductivity and fast electron transfer kinetics. By in situ plating with a bismuth film (BiF), the developed electrode exhibited well-defined and separate peaks for Zn(II), Cd(II), and Pb(II) by square wave anodic stripping voltammetry (SWASV). Analytical characteristics of the BiF/N/IL/G/SPCE were explored with calibration curves which were found to be linear for Zn(II), Cd(II), and Pb(II) concentrations over the range from 0.1 to 100.0 ng L(-1). With an accumulation period of 120 s detection limits of 0.09 ng mL(-1), 0.06 ng L(-1) and 0.08 ng L(-1) were obtained for Zn(II), Cd(II) and Pb(II), respectively using the BiF/N/IL/G/SPCE sensor, calculated as 3σ value of the blank. In addition, the developed electrode displayed a good repeatability and reproducibility. The interference from other common ions associated with Zn(II), Cd(II) and Pb(II) detection could be effectively avoided. Finally, the proposed analytical procedure was applied to detect the trace metal ions in drinking water samples with satisfactory results which demonstrates the suitability of the BiF/N/IL/G/SPCE to detect heavy metals in water samples and the results agreed well with those obtained by inductively coupled plasma mass spectrometry.

  10. Additive effect of ionic liquids on the electrochemical property of a sulfur composite electrode for all-solid-state lithium-sulfur battery

    NASA Astrophysics Data System (ADS)

    Kinoshita, Shunji; Okuda, Kazuya; Machida, Nobuya; Shigematsu, Toshihiko

    2014-12-01

    We investigated additive effect of five kinds of ionic liquids, such as 1-ethyl-3-methyl-imidazolium bis(trifluoromethane-sulfonyl)imide [EMI][TFSI], 1-ethyl-3-methyl-imidazolium tetrafluoroborate [EMI][BF4], 1-buthyl-3-methyl-imidazolium bis(trifluoromethane- sulfonyl) imide [BMI][TFSI], 1-buthyl-3-methyl-imidazolium tetrafluoroborate [BMI][BF4], and/or 1-buthyl-3-methyl-imidazolium iodide [BMI][I], on electrochemical properties of the sulfur composite electrode for all-solid-state lithium-sulfur batteries. The sulfur composite electrode that was composed of sulfur (29.9 wt%), vapor-grown carbon fiber (VGCF, 9.9 wt%), solid electrolyte (amorphous Li3PS4, 60.0 wt%), and [EMI][TFSI] (0.2 wt%) showed high initial specific capacity of 1270 mAh g-1 at 25 °C, which was calculated on the base of the weight of sulfur. To construct a laboratory-scale all-solid-state battery, amorphous Li3PS4 and meta-stable Li4.4Si alloy were used as solid electrolyte and as negative electrode materials, respectively. The laboratory-scale all-solid-state battery showed good discharge-charge cycle performance under a constant current density of 0.1 mA cm-2 (24 mA g-1) at room temperature and retained the large specific capacity more than 1230 mAh g-1 even after 50 cycles at 25 °C. The capacity after 50 cycles was about 97% of the initial capacity of the test cell.

  11. Simultaneous removal of methylene blue and copper(II) ions by photoelectron catalytic oxidation using stannic oxide modified iron(III) oxide composite electrodes.

    PubMed

    Qi, Jinqiu; Li, Xiaochen; Zheng, Hao; Li, Peiqiang; Wang, Huying

    2015-08-15

    Stannic oxide modified Fe(III) oxide composite electrodes (SnO2/Fe2O3) were synthesized for simultaneously removing methylene blue (MB) and Cu(II) from wastewater using photoelectron catalytic oxidation (PEO). The SnO2/Fe2O3 electrodes were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoelectrochemical techniques. The removal of MB and Cu(II) by PEO using the SnO2/Fe2O3 composite electrodes was studied in terms of reaction time, electric current density, and pH of the electrolyte. The kinetics of the reactions were investigated using batch assays. The optimal reaction time, pH, and electric current density of the PEO process were determined to be 30 min, 6.0, and 10 mA/cm(2), respectively. The removal rates of MB from wastewater treated by PEO and electron catalytic oxidation process were 84.87% and 70.64%, respectively, while the recovery rates of Cu(II) were 91.75% and 96.78%, respectively. The results suggest that PEO is an effective method for the simultaneous removal of MB and Cu(II) from wastewater, and the PEO process exhibits a much higher removal rate for MB and Cu(II) compared to the electron catalytic oxidation process. Furthermore, the removal of MB was found to follow the Langmuir-Freundlich-Hinshelwood kinetic model, whereas the removal of Cu(II) fitted well to the first-order reaction model.

  12. Fabrication and characterization of TiO2-NTs based hollow carbon fibers/carbon film composite electrode with NiOx decorated for capacitive application

    NASA Astrophysics Data System (ADS)

    Wei, Kajia; Wang, Yi; Han, Weiqing; Li, Jiansheng; Sun, Xiuyun; Shen, Jinyou; Wang, Lianjun

    2016-06-01

    This work designs a novel structure of TiO2 nanotubes (TiO2-NTs) based hollow carbon nanofibers (HCFs)/carbon film (CF) composite electrode with NiOx decorated for capacitive deionization application. The TiO2-NTs array is obtained through anode oxidation method on the titanium substrate, while the HCFs/CF is synthesized by thermal decomposition of a mixture of C6H12O6 and Ni(CH3COO)2·4H2O inside the nanochannels and over the caps of TiO2-NTs array, then followed by carbonization and HNO3 activation. The nickel possesses multi-functional effects during the synthesis process as carbon catalyst (Ni(II)), molecule binder (NiTi) and pseudo-capacitance supplier (NiOx). FE-SEM, XRD, Raman spectroscopy and water contact angle measurement reveal a uniform carbon distribution, favorable nickel dispersion, high stability and ideal hydrophilicity for this structure. With the addition of C6H12O6 and Ni(Ac)2·4H2O controlled at 10% (wt) and 2% (wt), respectively, a composite electrode with specific capacitance of 244.9 F·g-1, high oxygen evolution potential of 2.15 V and low water contact angle of 41.77° is obtained as well as minimum polarization impedance and efficient capacitive ability, which exhibits promising applications for practical employment.

  13. Li EXCESS Li4+xTi5-xO12-δ/C COMPOSITE USING SPRAY-DRYING METHOD AND ITS ELECTRODE PROPERTIES

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Daisuke; Suzuki, Norio; Kadoma, Yoshihiro; Ui, Koichi; Kumagai, Naoaki

    2012-03-01

    We have prepared a lithium excess carbon composite material, Li4+xTi5-xO12-δ/C (LTO/C), using various amounts of sucrose as a carbon source by the spray-drying method. The prepared materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and elemental analysis. The prepared material had the Li4Ti5O12 phase including 3.9-18.4 wt.% carbon. Transmission electron microscopy images and the selected area diffraction (SAD) pattern showed that the prepared materials consisted of a carbon nanonetwork in the LTO/C composite. The charge-discharge cycling tests were carried out using the R2032 coin-type cell under the following conditions; 1.2-3.0 V, 0.1 C-10 C (1 C = 175 mA g-1), 25°C. Based on the electrochemical results, the electrode performance of the prepared material was improved with increasing amounts of residual carbon, in particular, LTO/C including 6.2 wt.% residual carbon exhibited the best electrode performance of 156 mAh g-1 at 1 C during 50 cyclings when compared to the other materials.

  14. The Electrochemistry of Fe 3 O 4 /Polypyrrole Composite Electrodes in Lithium-Ion Cells: The Role of Polypyrrole in Capacity Retention

    DOE PAGES

    Bruck, Andrea M.; Gannett, Cara N.; Bock, David C.; ...

    2016-12-15

    In two series of magnetite (Fe3O4) composite electrodes, one group with and one group without added carbon, containing varying quantities of polypyrrole (PPy), and a non-conductive polyvinylidene difluoride (PVDF) binder were constructed and then analyzed using electrochemical and spectroscopic techniques. Galvanostatic cycling and alternating current (AC) impedance measurements were used in tandem to measure delivered capacity, capacity retention, and the related impedance at various stages of discharge and charge. Further, the reversibility of Fe3O4 to iron metal (Fe0) conversion observed during discharge was quantitatively assessed ex-situ using X-ray Absorption Spectroscopy (XAS). The Fe3O4 composite containing the largest weight fraction ofmore » PPy (20 wt%) with added carbon demonstrated reduced irreversible capacity on initial cycles and improved cycling stability over 50 cycles, attributed to decreased reaction with the electrolyte in the presence of PPy. Our study illustrated the beneficial role of PPy addition to Fe3O4 based electrodes was not strongly related to improved electrical conductivity, but rather to improved ion transport related to the formation of a more favorable surface electrolyte interphase (SEI).« less

  15. The Electrochemistry of Fe 3 O 4 /Polypyrrole Composite Electrodes in Lithium-Ion Cells: The Role of Polypyrrole in Capacity Retention

    SciTech Connect

    Bruck, Andrea M.; Gannett, Cara N.; Bock, David C.; Smith, Paul F.; Marschilok, Amy C.; Takeuchi, Kenneth J.; Takeuchi, Esther S.

    2016-12-15

    In two series of magnetite (Fe3O4) composite electrodes, one group with and one group without added carbon, containing varying quantities of polypyrrole (PPy), and a non-conductive polyvinylidene difluoride (PVDF) binder were constructed and then analyzed using electrochemical and spectroscopic techniques. Galvanostatic cycling and alternating current (AC) impedance measurements were used in tandem to measure delivered capacity, capacity retention, and the related impedance at various stages of discharge and charge. Further, the reversibility of Fe3O4 to iron metal (Fe0) conversion observed during discharge was quantitatively assessed ex-situ using X-ray Absorption Spectroscopy (XAS). The Fe3O4 composite containing the largest weight fraction of PPy (20 wt%) with added carbon demonstrated reduced irreversible capacity on initial cycles and improved cycling stability over 50 cycles, attributed to decreased reaction with the electrolyte in the presence of PPy. Our study illustrated the beneficial role of PPy addition to Fe3O4 based electrodes was not strongly related to improved electrical conductivity, but rather to improved ion transport related to the formation of a more favorable surface electrolyte interphase (SEI).

  16. Overoxidized polypyrrole/multi-walled carbon nanotubes composite modified electrode for in vivo liquid chromatography-electrochemical detection of dopamine.

    PubMed

    Wen, Jingxia; Zhou, Li; Jin, Litong; Cao, Xuni; Ye, Bang-Ce

    2009-07-01

    Overoxidized polypyrrole/multi-walled carbon nanotubes (OPPy/MWNTs) modified electrode has been developed for sensitively detecting dopamine (DA). OPPy films developed outside MWNTs might have a porous morphology. Thus, OPPy/MWNTs films developed by this method do not reject ascorbic acid (AA). However, OPPy/MWNTs modified electrode shows largely enhancing oxidative current responses of DA. When combined with liquid chromatography, it not only obtains a low detection limit of 7.5 x 10(-10) mol L(-1) for DA, but also improves the selectivity of DA detection. Mechanisms for the enhancement are also well discussed in this paper. With this approach, microdialysis has been employed for successful assessment of DA in rat striatum.

  17. Polymer-Derived Ceramic Functionalized MoS2 Composite Paper as a Stable Lithium-Ion Battery Electrode.

    PubMed

    David, L; Bhandavat, R; Barrera, U; Singh, G

    2015-04-08

    A facile process is demonstrated for the synthesis of layered SiCN-MoS2 structure via pyrolysis of polysilazane functionalized MoS2 flakes. The layered morphology and polymer to ceramic transformation on MoS2 surfaces was confirmed by use of electron microscopy and spectroscopic techniques. Tested as thick film electrode in a Li-ion battery half-cell, SiCN-MoS2 showed the classical three-stage reaction with improved cycling stability and capacity retention than neat MoS2. Contribution of conversion reaction of Li/MoS2 system on overall capacity was marginally affected by the presence of SiCN while Li-irreversibility arising from electrolyte decomposition was greatly suppressed. This is understood as one of the reasons for decreased first cycle loss and increased capacity retention. SiCN-MoS2 in the form of self-supporting paper electrode (at 6 mg·cm(-2)) exhibited even better performance, regaining initial charge capacity of approximately 530 mAh·g(-1) when the current density returned to 100 mA·g(-1) after continuous cycling at 2400 mA·g(-1) (192 mAh·g(-1)). MoS2 cycled electrode showed mud-cracks and film delamination whereas SiCN-MoS2 electrodes were intact and covered with a uniform solid electrolyte interphase coating. Taken together, our results suggest that molecular level interfacing with precursor-derived SiCN is an effective strategy for suppressing the metal-sulfide/electrolyte degradation reaction at low discharge potentials.

  18. Polymer-Derived Ceramic Functionalized MoS2 Composite Paper as a Stable Lithium-Ion Battery Electrode

    NASA Astrophysics Data System (ADS)

    David, L.; Bhandavat, R.; Barrera, U.; Singh, G.

    2015-04-01

    A facile process is demonstrated for the synthesis of layered SiCN-MoS2 structure via pyrolysis of polysilazane functionalized MoS2 flakes. The layered morphology and polymer to ceramic transformation on MoS2 surfaces was confirmed by use of electron microscopy and spectroscopic techniques. Tested as thick film electrode in a Li-ion battery half-cell, SiCN-MoS2 showed the classical three-stage reaction with improved cycling stability and capacity retention than neat MoS2. Contribution of conversion reaction of Li/MoS2 system on overall capacity was marginally affected by the presence of SiCN while Li-irreversibility arising from electrolyte decomposition was greatly suppressed. This is understood as one of the reasons for decreased first cycle loss and increased capacity retention. SiCN-MoS2 in the form of self-supporting paper electrode (at 6 mg.cm-2) exhibited even better performance, regaining initial charge capacity of approximately 530 mAh.g-1 when the current density returned to 100 mA.g-1 after continuous cycling at 2400 mA.g-1 (192 mAh.g-1). MoS2 cycled electrode showed mud-cracks and film delamination whereas SiCN-MoS2 electrodes were intact and covered with a uniform solid electrolyte interphase coating. Taken together, our results suggest that molecular level interfacing with precursor-derived SiCN is an effective strategy for suppressing the metal-sulfide/electrolyte degradation reaction at low discharge potentials.

  19. Highly Conductive and Uniform Alginate/Silver Nanowire Composite Transparent Electrode by Room Temperature Solution Processing for Organic Light Emitting Diode.

    PubMed

    Lian, Lu; Dong, Dan; Yang, Shuai; Wei, Bingwu; He, Gufeng

    2017-04-05

    A novel transparent electrode composed of alginate/silver nanowire (AgNW) with high conductivity and low roughness is fabricated via a solution process at room temperature. The sol-gel transition of the alginate triggered by CaCl2 solution bonds the AgNWs to the substrate tightly. Meanwhile, Cl(-) in the solution can renovate the cracks on the AgNW surfaces created during the mechanical pressing, resulting in a great increase of the electrical conductivity. The alginate/AgNW composite film can reach a sheet resistance of 2.3 Ω/sq with a transmittance of 83% at 550 nm. The conductivity of the composite film remains stable after bending and tape tests, demonstrating excellent flexibility and great adhesion of AgNWs to the substrate. Moreover, the composite film shows better stability to resist longtime storage than conventional annealed-AgNW film. The organic light emitting diode using such alginate/AgNW composite film as anode presents current densities and luminances comparable to those of indium tin oxide (ITO) anode, and higher efficiencies are obtained due to the better charge balance.

  20. Enhanced photoelectrochemical water splitting from Si quantum dots/TiO{sub 2} nanotube arrays composite electrodes

    SciTech Connect

    Li, Zhong; Cui, Xiaoli; Hao, Hongchen; Lu, Ming; Lin, Yuehe

    2015-06-15

    Graphical abstract: Si quantum dots were firstly applied to modify TiO{sub 2} nanotubes and enhanced visible light response was demonstrated for the resulted Si QDs/TiO{sub 2} nanocomposite. Si QDs are promising in photoelectrochemical water splitting and photocatalysis since their low cost, abundance and environmentally-friendliness. - Highlights: • A novel nanocomposite Si QDs/TiO{sub 2} nanotubes was fabricated and characterized. • Enhanced photoelectrochemical water splitting was firstly demonstrated for Si QDs/TiO{sub 2}. • The visible light response of TiO{sub 2} increased with the presence of Si QDs. - Abstract: This work firstly introduced Si quantum dots (QDs) to modify TiO{sub 2} nanotube arrays for photoelectrochemical water splitting. A systematic study using surface and optical characterization tools reveals the nature of the combination of Si QDs and TiO{sub 2} nanotube arrays. Scanning electron microscopy and X-ray photoelectron spectroscopy results show that Si QDs were assembled on the surface of vertically aligned TiO{sub 2} nanotube arrays. The UV–vis diffuse reflectance spectra indicate the improved visible light absorbance. The enhanced photoelectrochemical water splitting was demonstrated under visible light illumination and the photocurrent density was 1.6 times larger than that of pristine TiO{sub 2} electrodes. Electrochemical impedance behavior was measured for the electrodes and the impedance is slightly reduced for the nanocomposite electrode with the presence of Si QDs. This work demonstrated that Si QDs would be a novel and effective choice for improving the utilization of visible light for TiO{sub 2} nanotubes.

  1. Simultaneous Production of High-Performance Flexible Textile Electrodes and Fiber Electrodes for Wearable Energy Storage.

    PubMed

    Dong, Liubing; Xu, Chengjun; Li, Yang; Wu, Changle; Jiang, Baozheng; Yang, Qian; Zhou, Enlou; Kang, Feiyu; Yang, Quan-Hong

    2016-02-24

    High-performance flexible textile electrodes and fiber electrodes are produced simultaneously by a newly proposed effective strategy. Activated carbon fiber cloth (ACFC)/carbon nanotubes (CNTs) and ACFC/MnO2/CNTs composites are designed as high-performance flexible textile electrodes. Theses textiles can also be easily dismantled into individual fiber bundles used as high-performance flexible fiber electrodes.

  2. Binder-free nitrogen-doped carbon paper electrodes derived from polypyrrole/cellulose composite for Li-O2 batteries

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Wang, Zhaohui; Zhu, Jiefang

    2016-02-01

    This work presents a novel binder-free nitrogen-doped carbon paper electrode (NCPE), which was derived from a N-rich polypyrrole (PPy)/cellulose-chopped carbon filaments (CCFs) composite, for Li-O2 batteries. The fabrication of NCPE involved cheap raw materials (e.g., Cladophora sp. green algae) and easy operation (e.g., doping N by a carbonization of N-rich polymer), which is especially suitable for large-scale production. The NCPE exhibited a bird's nest microstructure, which could provide the self-standing electrode with considerable mechanic durability, fast Li+ and O2 diffusion, and enough space for the discharge product deposition. In addition, the NCPE contained N-containing function groups, which may promote the electrochemical reactions. Furthermore, binder-free architecture designs can prevent binder-involved parasitic reactions. A Li-O2 cell with the NCPE displayed a cyclability of more than 30 cycles at a constant current density of 0.1 mA/cm2. The 1st discharge capacity for a cell with the NCPE reached 8040 mAh/g at a current density of 0.1 mA/cm2, with a cell voltage around 2.81 V. A cell with the NCPE displayed a coulombic efficiency of 81% on the 1st cycle at a current density of 0.2 mA/cm2. These results represent a promising progress in the development of a low-cost and versatile paper-based O2 electrode for Li-O2 batteries.

  3. Surface chemical analysis of CuO nanofiber composite electrodes at different stages of lithiation/delithiation

    NASA Astrophysics Data System (ADS)

    Gangaja, Binitha; Chandrasekharan, Sruthi; Vadukumpully, Sajini; Nair, Shantikumar V.; Santhanagopalan, Dhamodaran

    2017-02-01

    High aspect ratio, electrospun CuO nanofibers have been fabricated and tested for its electrochemical performance as lithium ion battery anode. These nanofibers are composed of CuO nanoparticles about 35-40 nm in size forming good inter-connected network. Fabricated half cells maintained specific capacity of 310 mAh g-1 at 1C rate for 100 cycles and stabilized capacity of about 120 mAh g-1 at 5C rate for 1000 cycles. Ex situ x-ray photoelectron spectroscopy (XPS) was performed to understand the electrodes surface chemical changes at the end of first discharge, first charge and after tenth charge. The solid electrolyte interface (SEI) layer comprised of LiF, Li2CO3 and Li2O while their quantity varied depending on the stage of lithiation/delithiation. Initially, no copper signal is observed on the surface of the SEI layer. However, in situ sputtering of the electrodes in the XPS chamber revealed that at the end of first discharge, formation Cu0 with detectable fraction of LixCuO2 and hydroxide in the SEI layer. At the end of first charge, a large fraction of Cu2O phase with a small fraction of hydroxide is observed. At the end of 10th charge no change in SEI layer content but increase in thickness was observed.

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

    PubMed

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

    2016-12-01

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

  5. Simultaneous determination of ascorbic acid and rutin in pharmaceutical preparations with electrochemical method based on multi-walled carbon nanotubes-chitosan composite film modified electrode.

    PubMed

    Deng, Peihong; Xu, Zhifeng; Li, Junhua

    2013-03-25

    In this paper, the simultaneous voltammetric determination of ascorbic acid (AA) and rutin (Ru) has been achieved at an acetylene black paste electrode modified with multi-walled carbon nanotubes-chitosan composite film (denoted as MWCNTs-CHIT/ABPE). Compared with bare electrode, the peak currents of AA and Ru at MWCNTs-CHIT/ABPE increased greatly and the anodic peak potential difference (ΔE(pa)) between AA and Ru are up to 342mV, which is undoubtedly attributed to the unique characteristics of AB and MWCNTs such as excellent electric conductivity, high surface area and strong adsorptive abilities, resulting in higher accumulation efficiency to AA and Ru. The influences of some experimental conditions on the oxidation of AA and Ru were tested and the calibration plot was examined. Under the optimized condition, a good linearity was obtained in the concentration range of 1μM-0.4mM for AA in the presence of 10μM Ru and 20nM-10μM for Ru in the presence of 1mM AA. The detection limits (S/N=3) of AA and Ru are 0.8μM and 10nM, respectively. The proposed method was successfully applied to the simultaneous determination of AA and Ru in pharmaceutical samples with reliable recovery.

  6. Selective and sensitive determination of uric acid in the presence of ascorbic acid and dopamine by PDDA functionalized graphene/graphite composite electrode.

    PubMed

    Yu, Yanyan; Chen, Zuanguang; Zhang, Beibei; Li, Xinchun; Pan, Jianbin

    2013-08-15

    In this work, a facile electrochemical sensor based on poly(diallyldimethylammonium chloride) (PDDA) functionalized graphene (PDDA-G) and graphite was fabricated. The composite electrode exhibited excellent selectivity and sensitivity towards uric acid (UA), owing to the electrocatalytic effect of graphene nanosheets and the electrostatic attractions between PDDA-G and UA. The anodic peak current of UA obtained by cyclic voltammetry (CV) increased over 10-fold compared with bare carbon paste electrode (CPE). And the reversibility of the oxidation process was improved significantly. Differential pulse voltammetry (DPV) was used to determine UA in the presence of ascorbic acid (AA) and dopamine (DA). It was found that all of oxidation peaks of three species could be well resolved, and the peak current of UA was much stronger than the other two components. More importantly, considerable-amount of AA and DA showed negligible interference to UA assay. The calibration curve for UA ranged from 0.5 to 20 μmol L(-1) with a correlation coefficient of 0.9934. The constructed sensor has been employed to quantitatively determine UA in urine samples.

  7. Metal-organic frameworks and β-cyclodextrin-based composite electrode for simultaneous quantification of guanine and adenine in a lab-on-valve manifold.

    PubMed

    Wang, Yang; Chen, Huanhuan; Wu, Yichun; Ge, Huali; Ye, Guiqin; Hu, Xiaoya

    2014-12-07

    In this work, a novel chemically modified electrode is constructed based on metal-organic frameworks and β-cyclodextrin (Cu3(BTC)2/β-CD, BTC = benzene-1,3,5-tricarboxylate) composite material. The electrode was used for simultaneous determination of guanine and adenine in a sequential injection lab-on-valve format and exhibited sensitive responses to guanine and adenine oxidation due to the π-π stacking interaction of Cu3(BTC)2 and the inclusion behavior of β-CD. The analytical performance was assessed with respect to the supporting electrolyte and its pH, accumulation time and accumulation potential, and the fluid flow rates. Under optimal conditions, linear calibration ranges for both guanine and adenine were from 1.0 × 10(-7) to 1.0 × 10(-5) mol L(-1), and detection limits (S/N = 3) were found to be 5.2 × 10(-8) and 2.8 × 10(-8) mol L(-1), respectively. The proposed sensor showed advantages of high sensitivity, simple sample preparation protocol, enhanced throughput and good reproducibility. Finally, the practical application of the proposed sensor has been performed for the determination of guanine and adenine in real samples with satisfactory results.

  8. An electrochemical sensor for warfarin determination based on covalent immobilization of quantum dots onto carboxylated multiwalled carbon nanotubes and chitosan composite film modified electrode.

    PubMed

    Gholivand, Mohammad Bagher; Mohammadi-Behzad, Leila

    2015-12-01

    A method is described for the construction of a novel electrochemical warfarin sensor based on covalent immobilization of CdS-quantum dots (CdS-QDs) onto carboxylated multiwalled carbon nanotubes/chitosan (CS) composite film on the surface of a glassy carbon electrode. The CdS-QDs/CS/MWCNTs were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, XRD analysis and electrochemical impedance spectroscopy (EIS). The sensor showed optimum anodic stripping response within 90s at an accumulation potential of 0.75V. The modified electrode was used to detect the concentration of warfarin with a wide linear range of 0.05-80 μM and a detection limit (S/N=3) of 8.5 nM. The proposed sensor has good storage stability, repeatability and reproducibility and was successfully applied for the determination of warfarin in real samples such as urine, serum and milk.

  9. A novel electrochemical sensor based on Au@PANI composites film modified glassy carbon electrode binding molecular imprinting technique for the determination of melamine.

    PubMed

    Rao, Hanbing; Chen, Min; Ge, Hongwei; Lu, Zhiwei; Liu, Xin; Zou, Ping; Wang, Xianxiang; He, Hua; Zeng, Xianyin; Wang, Yanying

    2017-01-15

    A novel molecularly imprinted electrochemical sensor for the rapid detection of melamine was reported in this paper. Glassy carbon electrode (GCE) was modified by Au and polyaniline composites (Au@PANI) deposited on the surface of GCE and were used to increase the electrode sensitivity and to amplify the sensor signal. Melamine template molecule was further assembled onto Au@PANI by the formation of hydrogen bonds, can implement the selective detection of melamine. This simple but efficient electrochemistry analysis platform presents a low detection limit of 1.39×10(-6)µmolL(-1) for detection of melamine, which is remarkably lower than the currently used methods and the previous reports. So, this method may open a new way for the determination of melamine which enables low cost, effective and sensitive determination. This shows the sensor can be potentially utilized for the detection of melamine in food, which allows the sensitive and selective determination of melamine from milk and feed.

  10. An analysis of electrochemical energy storage using electrodes fabricated from atomically thin 2D structures of MoS2, graphene and MoS2/graphene composites

    NASA Astrophysics Data System (ADS)

    Huffstutler, Jacob D.

    The behavior of 2D materials has become of great interest in the wake of development of electrochemical double-layer capacitors (EDLCs) and the discovery of monolayer graphene by Geim and Novoselov. This study aims to analyze the response variance of 2D electrode materials for EDLCs prepared through the liquid-phase exfoliation method when subjected to differing conditions. Once exfoliated, samples are tested with a series of structural characterization methods, including tunneling electron microscopy, atomic force microscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. A new ionic liquid for EDLC use, 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate is compared in performance to 6M potassium hydroxide aqueous electrolyte. Devices composed of liquid-phase exfoliated graphene / MoS2 composites are analyzed by concentration for ideal performance. Device performance under cold extreme temperatures for the ionic fluid is presented as well. A brief overview of by-layer analysis of graphene electrode materials is presented as-is. All samples were tested with cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy, with good capacitive results. The evolution of electrochemical behavior through the altered parameters is tracked as well.

  11. A novel Laccase Biosensor based on Laccase immobilized Graphene-Cellulose Microfiber Composite modified Screen-Printed Carbon Electrode for Sensitive Determination of Catechol.

    PubMed

    Palanisamy, Selvakumar; Ramaraj, Sayee Kannan; Chen, Shen-Ming; Yang, Thomas C K; Yi-Fan, Pan; Chen, Tse-Wei; Velusamy, Vijayalakshmi; Selvam, Sonadevi

    2017-01-24

    In the present work, we demonstrate the fabrication of laccase biosensor to detect the catechol (CC) using laccase immobilized on graphene-cellulose microfibers (GR-CMF) composite modified screen printed carbon electrode (SPCE). The direct electrochemical behavior of laccase was investigated using laccase immobilized different modified SPCEs, such as GR/SPCE, CMF/SPCE and GR-CMF/SPCE. Compared with laccase immobilized GR and CMF modified SPCEs, a well-defined redox couple of Cu(I)/Cu(II) for laccase was observed at laccase immobilized GR-CMF composite modified SPCE. Cyclic voltammetry results show that the as-prepared biosensor has 7 folds higher catalytic activity with lower oxidation potential towards CC than SPCE modified with GR-CMF composite. Under optimized conditions, amperometric i-t method was used for the quantification of CC, and the amperometric response of the biosensor was linear over the concertation of CC ranging from 0.2 to 209.7 μM. The sensitivity, response time and the detection limit of the biosensor for CC is 0.932 μMμA(-1) cm(-2), 2 s and 0.085 μM, respectively. The biosensor has high selectivity towards CC in the presence of potentially active biomolecules and phenolic compounds. The biosensor also accessed for the detection of CC in different water samples and shows good practicality with an appropriate repea.

  12. A novel Laccase Biosensor based on Laccase immobilized Graphene-Cellulose Microfiber Composite modified Screen-Printed Carbon Electrode for Sensitive Determination of Catechol

    PubMed Central

    Palanisamy, Selvakumar; Ramaraj, Sayee Kannan; Chen, Shen-Ming; Yang, Thomas C. K.; Yi-Fan, Pan; Chen, Tse-Wei; Velusamy, Vijayalakshmi; Selvam, Sonadevi

    2017-01-01

    In the present work, we demonstrate the fabrication of laccase biosensor to detect the catechol (CC) using laccase immobilized on graphene-cellulose microfibers (GR-CMF) composite modified screen printed carbon electrode (SPCE). The direct electrochemical behavior of laccase was investigated using laccase immobilized different modified SPCEs, such as GR/SPCE, CMF/SPCE and GR-CMF/SPCE. Compared with laccase immobilized GR and CMF modified SPCEs, a well-defined redox couple of CuI/CuII for laccase was observed at laccase immobilized GR-CMF composite modified SPCE. Cyclic voltammetry results show that the as-prepared biosensor has 7 folds higher catalytic activity with lower oxidation potential towards CC than SPCE modified with GR-CMF composite. Under optimized conditions, amperometric i-t method was used for the quantification of CC, and the amperometric response of the biosensor was linear over the concertation of CC ranging from 0.2 to 209.7 μM. The sensitivity, response time and the detection limit of the biosensor for CC is 0.932 μMμA−1 cm−2, 2 s and 0.085 μM, respectively. The biosensor has high selectivity towards CC in the presence of potentially active biomolecules and phenolic compounds. The biosensor also accessed for the detection of CC in different water samples and shows good practicality with an appropriate repea. PMID:28117357

  13. Low-cost Cr doped Pt3Ni alloy supported on carbon nanofibers composites counter electrode for efficient dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Xiao, Junying; Cui, Midou; Wang, Mingkun; Sui, Huidong; Yang, Kun; Li, Ling; Zhang, Wenming; Li, Xiaowei; Fu, Guangsheng; Hagfeldt, Anders; Zhang, Yucang

    2016-10-01

    Pt3Ni alloy supported by carbon nanofibers (CNs) composites (Pt3Ni/CNs) synthesized by a simple solvothermal process was introduced into dye-sensitized solar cells (DSCs) as counter electrode (CE) for the first time, and the DSCs based on Pt3Ni/CNs CE obtained a power conversion efficiency (PCE) of 8.34%. To enhance the catalytic activity of Pt3Ni/CNs composites, transition metal chrome (Cr) was doped in Pt3Ni/CNs to synthesize the composites of Cr-Pt3Ni/CNs using the same method. Due to the high electrocatalytic activity and rapid charge transfer ability, the PCE of the DSCs employing Cr-Pt3Ni/CNs as CE increased to 8.76%, which was much higher than that of Pt CE (7.04%) measured in the same condition. The impressive results along with low cost and simple synthesis process demonstrated transition metal doping was a promising method to produce substitutes for Pt to reduce the cost and increase the PCE of DSCs.

  14. Hybrid nanostructured microporous carbon-mesoporous carbon doped titanium dioxide/sulfur composite positive electrode materials for rechargeable lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Zegeye, Tilahun Awoke; Kuo, Chung-Feng Jeffrey; Wotango, Aselefech Sorsa; Pan, Chun-Jern; Chen, Hung-Ming; Haregewoin, Atetegeb Meazah; Cheng, Ju-Hsiang; Su, Wei-Nien; Hwang, Bing-Joe

    2016-08-01

    Herein, we design hybrid nanostructured microporous carbon-mesoporous carbon doped titanium dioxide/sulfur composite (MC-Meso C-doped TiO2/S) as a positive electrode material for lithium-sulfur batteries. The hybrid MC-Meso C-doped TiO2 host material is produced by a low-cost, hydrothermal and annealing process. The resulting conductive material shows dual microporous and mesoporous behavior which enhances the effective trapping of sulfur and polysulfides. The hybrid MC-Meso C-doped TiO2/S composite material possesses rutile TiO2 nanotube structure with successful carbon doping while sulfur is uniformly distributed in the hybrid MC-Meso C-doped TiO2 composite materials after the melt-infusion process. The electrochemical measurement of the hybrid material also shows improved cycle stability and rate performance with high sulfur loading (61.04%). The material delivers an initial discharge capacity of 802 mAh g-1 and maintains it at 578 mAh g-1 with a columbic efficiency greater than 97.1% after 140 cycles at 0.1 C. This improvement is thought to be attributed to the unique hybrid nanostructure of the MC-Meso C-doped TiO2 host and the good dispersion of sulfur in the narrow pores of the MC spheres and the mesoporous C-doped TiO2 support.

  15. Glassy carbon electrode modified with horse radish peroxidase/organic nucleophilic-functionalized carbon nanotube composite for enhanced electrocatalytic oxidation and efficient voltammetric sensing of levodopa.

    PubMed

    Shoja, Yalda; Rafati, Amir Abbas; Ghodsi, Javad

    2016-01-01

    A novel and selective enzymatic biosensor was designed and constructed for voltammetric determination of levodopa (L-Dopa) in aqueous media (phosphate buffer solution, pH=7). Biosensor development was on the basis of to physically immobilizing of horse radish peroxidase (HRP) as electrochemical catalyst by sol-gel on glassy carbon electrode modified with organic nucleophilic carbon nanotube composite which in this composite p-phenylenediamine (pPDA) as organic nucleophile chemically bonded with functionalized MWCNT (MWCNT-COOH). The results of this study suggest that prepared bioorganic nucleophilic carbon nanotube composite (HRP/MWCNT-pPDA) shows fast electron transfer rate for electro oxidation of L-Dopa because of its high electrochemical catalytic activity toward the oxidation of L-Dopa, more--NH2 reactive sites and large effective surface area. Also in this work we measured L-Dopa in the presence of folic acid and uric acid as interferences. The proposed biosensor was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), FT-IR spectroscopy and cyclic voltammetry (CV). The differential pulse voltammetry (DPV) was used for determination of L-Dopa from 0.1 μM to 1.9 μM with a low detection limit of 40 nM (for S/N=3) and sensitivity was about 35.5 μA/μM. Also this biosensor has several advantages such as rapid response, high stability and reproducibility.

  16. Improved performance of electrodes based on carbonized olive stones/S composites by impregnating with mesoporous TiO2 for advanced Lisbnd S batteries

    NASA Astrophysics Data System (ADS)

    Moreno, Noelia; Caballero, Álvaro; Morales, Julián; Rodríguez-Castellón, Enrique

    2016-05-01

    Carbons obtained from biomass have attracted a lot of attention for use as electrodes for Li-ion batteries. Less attention has been paid to their use in Lisbnd S batteries in spite of the higher energy densities. Here, we optimized the electrochemical properties of an activated carbon (OSAC) obtained from olive stones with the help of mesoporous TiO2. The OSAC@TiO2/S hybrid composite exhibited improved electrochemical performance compared with the OSAC/S composite. The presence of TiO2 increased the delivered capacity of the cell by more than 60%, and the rate capability was notably improved. The cell could operate at current densities of 3350 mA g-1 (2 C), releasing an average capacity of 500 mAh g-1 with a coulombic efficiency close to 100%. This improvement in the electrochemical performance is attributed to the sorbent properties of TiO2 towards Li polysulfides and its facility to insert Li, which enhances the electronic and ionic conductivity of the hybrid composite.

  17. A novel Laccase Biosensor based on Laccase immobilized Graphene-Cellulose Microfiber Composite modified Screen-Printed Carbon Electrode for Sensitive Determination of Catechol

    NASA Astrophysics Data System (ADS)

    Palanisamy, Selvakumar; Ramaraj, Sayee Kannan; Chen, Shen-Ming; Yang, Thomas C. K.; Yi-Fan, Pan; Chen, Tse-Wei; Velusamy, Vijayalakshmi; Selvam, Sonadevi

    2017-01-01

    In the present work, we demonstrate the fabrication of laccase biosensor to detect the catechol (CC) using laccase immobilized on graphene-cellulose microfibers (GR-CMF) composite modified screen printed carbon electrode (SPCE). The direct electrochemical behavior of laccase was investigated using laccase immobilized different modified SPCEs, such as GR/SPCE, CMF/SPCE and GR-CMF/SPCE. Compared with laccase immobilized GR and CMF modified SPCEs, a well-defined redox couple of CuI/CuII for laccase was observed at laccase immobilized GR-CMF composite modified SPCE. Cyclic voltammetry results show that the as-prepared biosensor has 7 folds higher catalytic activity with lower oxidation potential towards CC than SPCE modified with GR-CMF composite. Under optimized conditions, amperometric i-t method was used for the quantification of CC, and the amperometric response of the biosensor was linear over the concertation of CC ranging from 0.2 to 209.7 μM. The sensitivity, response time and the detection limit of the biosensor for CC is 0.932 μMμA‑1 cm‑2, 2 s and 0.085 μM, respectively. The biosensor has high selectivity towards CC in the presence of potentially active biomolecules and phenolic compounds. The biosensor also accessed for the detection of CC in different water samples and shows good practicality with an appropriate repea.

  18. Comparison of Electrodes for High-Performance Electrochemical Capacitors: Multi-Layer MnO2/Pt and Composite MnO2/Pt on Carbon Nanofibres.

    PubMed

    Lee, Yu-Jin; An, Geon-Hyoung; Ahn, Hyo-Jin

    2015-11-01

    Four different types of electrodes for high-performance electrochemical capacitors were prepared using electrospinning method and/or impregnation methods: (1) conventional carbon nanofibres (CNF) supports, and CNFs decorated with (2) MnO2 nanophases, (3) multi-layer MnO2/Pt nanophases, and (4) composite MnO2 and Pt nanophases. Their morphological, structural, chemical, and electrochemical properties were characterized using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and galvanostatic charge/discharge measurements. Composite MnO2 and Pt nanophases decorated on the CNFs exhibited superior capacitance (-252.3 F/g at 10 mV/s), excellent capacitance retention (-93.5% after 300 cycles), and high energy densities (13.53-18.06 Wh/kg). The enhanced electrochemical performances can be explained by the composite structure, presenting well-dispersed MnO2 nanophases leading to high capacitance, and well-dispersed Pt nanophases leading to improved electrical conductivity.

  19. Preparation and electrochemical properties of NiO-Co3O4 composite as electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Wang, X. W.; Zheng, D. L.; Yang, P. Z.; Wang, X. E.; Zhu, Q. Q.; Ma, P. F.; Sun, L. Y.

    2017-01-01

    The precursor of NiO-Co3O4 composites was synthesized via a simple hydrothermal process. After that, the precursor was calcined at 300 °C for 3 h to obtain the composite powders. The powders calcined at 300 °C showed amorphous, and the powders calcined at 400 °C and 500 °C for comparison showed the composite phase of NiO and Co3O4. The composite products showed a microstructure of micro-spheres. For the samples calcined at 300 °C for 3 h, the specific capacitance reached 801 F g-1 at a current density of 1 A g-1.

  20. Electrochemical determination of bisphenol A in plastic bottled drinking water and canned beverages using a molecularly imprinted chitosan-graphene composite film modified electrode.

    PubMed

    Deng, Peihong; Xu, Zhifeng; Kuang, Yunfei

    2014-08-15

    Herein, a novel electrochemical sensor based on an acetylene black paste electrode modified with molecularly imprinted chitosan-graphene composite film for sensitive and selective detection of bisphenol A (BPA) has been developed. Several important parameters controlling the performance of the sensor were investigated and optimised. The imprinted sensor offers a fast response and sensitive BPA quantification. Under the optimal conditions, a linear range from 8.0 nM to 1.0 μM and 1.0 to 20 μM for the detection of BPA was observed with the detection limit of 6.0 nM (S/N=3). Meanwhile, the fabricated sensor showed excellent specific recognition to template molecule among the structural similarities and coexistence substances. Furthermore, this imprinted electrochemical sensor was successfully employed to detect BPA in plastic bottled drinking water and canned beverages.

  1. Effect of film composition on the performance of interdigitated electrode methods used for chemically amplified photoresist characterization: methods for analyzing photoresist materials containing base quencher

    NASA Astrophysics Data System (ADS)

    Berger, Cody; Henderson, Clifford L.

    2005-05-01

    Previously, a method which utilizes interdigitated electrode (IDE) sensors to collect capacitance versus exposure dose data for thin films containing a photoacid generator (PAG) and polymer and subsequently calculate the Dill C photoreaction rate constant for the photoacid generator has been presented. This paper discusses a method for extending such IDE methods to calculate the Dill C rate constant for a photoacid generator in a film containing a polymer, photoacid generator, and base quencher. This three component formulation more closely resembles the composition of commercial chemically amplified photoresists. It is shown that by using a data normalization approach, the IDE data can be successfully analyzed to compute accurate Dill C values for a PAG in the presence of base quencher and to estimate the concentration of base quencher in the film. The technique also thus allows for measurement of the impact of the presence of base quencher on the photoreaction rate constant of the photoacid generator.

  2. Electrochemical behavior and voltammetric determination of vanillin based on an acetylene black paste electrode modified with graphene-polyvinylpyrrolidone composite film.

    PubMed

    Deng, Peihong; Xu, Zhifeng; Zeng, Rongying; Ding, Chunxia

    2015-08-01

    The graphene-polyvinylpyrrolidone composite film modified acetylene black paste electrode (GR-PVP/ABPE) was fabricated and used to determine vanillin. In 0.1M H3PO4 solution, the oxidation peak current of vanillin increased significantly at GR-PVP/ABPE compared with bare ABPE, PVP/ABPE and GR/ABPE. The oxidation mechanism was discussed. The experimental conditions that exert influence on the voltammetric determination of vanillin, such as supporting electrolytes, pH values, accumulation potential and accumulation time, were optimized. Besides, the interference, repeatability, reproducibility and stability measurements were also evaluated. Under the optimal experimental conditions, the oxidation peak current was proportional to vanillin concentration in the range of 0.02-2.0 μM, 2.0-40 μM and 40-100 μM. The detection limit was 10nM. This sensor was used successfully for vanillin determination in various food samples.

  3. A Novel Electrochemical Sensor for Probing Doxepin Created on a Glassy Carbon Electrode Modified with Poly(4-Amino- benzoic Acid)/Multi-Walled Carbon Nanotubes Composite Film

    PubMed Central

    Xu, Xiao-Li; Huang, Fei; Zhou, Guo-Liang; Zhang, Song; Kong, Ji-Lie

    2010-01-01

    A novel electrochemical sensor for sensitive detection of doxepin was prepared, which was based on a glassy carbon electrode modified with poly(4-aminobenzoic acid)/multi-walled carbon nanotubes composite film [poly(4-ABA)/MWNTs/GCE]. The sensor was characterized by scanning electron microscopy and electrochemical methods. It was observed that poly(4-ABA)/MWNTs/GCE showed excellent preconcentration function and electrocatalytic activities towards doxepin. Under the selected conditions, the anodic peak current was linear to the logarithm of doxepin concentration in the range from 1.0 × 10−9 to 1.0 × 10−6 M, and the detection limit obtained was 1.0 × 10−10 M. The poly(4-ABA)/MWNTs/GCE was successfully applied in the measurement of doxepin in commercial pharmaceutical formulations, and the analytical accuracy was confirmed by comparison with a conventional ultraviolet spectrophotometry assay. PMID:22163661

  4. Graphene-multiwall carbon nanotube-gold nanocluster composites modified electrode for the simultaneous determination of ascorbic acid, dopamine, and uric acid.

    PubMed

    Liu, Xiaofang; Wei, Shaping; Chen, Shihong; Yuan, Dehua; Zhang, Wen

    2014-08-01

    In this paper, graphene-multiwall carbon nanotube-gold nanocluster (GP-MWCNT-AuNC) composites were synthesized and used as modifier to fabricate a sensor for simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA). The electrochemical behavior of the sensor was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The combination of GP, MWCNTs, and AuNCs endowed the electrode with a large surface area, good catalytic activity, and high selectivity and sensitivity. The linear response range for simultaneous detection of AA, DA, and UA at the sensor were 120-1,701, 2-213, and 0.7-88.3 μM, correspondingly, and the detection limits were 40, 0.67, and 0.23 μM (S/N=3), respectively. The proposed method offers a promise for simple, rapid, selective, and cost-effective analysis of small biomolecules.

  5. Long Life Durability of Electrodes of Electrical Resistance Change Method for Damage Monitoring of CFRP Composite Structures

    DTIC Science & Technology

    2008-03-01

    to measure fatigue limit of the CFRP laminates. Figure 12 shows the results of the fatigue tests. The abscissa is the number of cycles to failure and...monitoring of CFRP composite structures 2007 April – 2008 March Professor Akira Todoroki Department of Mechanical Sciences and Engineering Tokyo...monitoring of CFRP composite structures 5a. CONTRACT NUMBER FA48690714039 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Akira Todoroki 5d

  6. Sn x[BPO 4] 1-x composites as negative electrodes for lithium ion cells: Comparison with amorphous SnB 0.6P 0.4O 2.9 and effect of composition

    NASA Astrophysics Data System (ADS)

    Conte, Donato Ercole; Aboulaich, Abdelmaula; Robert, Florent; Olivier-Fourcade, Josette; Jumas, Jean-Claude; Jordy, Christian; Willmann, Patrick

    2010-01-01

    A comparative study of two Sn-based composite materials as negative electrode for Li-ion accumulators is presented. The former SnB 0.6P 0.4O 2.9 obtained by in-situ dispersion of SnO in an oxide matrix is shown to be an amorphous tin composite oxide (ATCO). The latter Sn 0.72[BPO 4] 0.28 obtained by ex-situ dispersion of Sn in a borophosphate matrix consists of Sn particles embedded in a crystalline BPO 4 matrix. The electrochemical responses of ATCO and Sn 0.72[BPO 4] 0.28 composite in galvanostatic mode show reversible capacities of about 450 and 530 mAh g -1, respectively, with different irreversible capacities (60% and 29%). Analysis of these composite materials by 119Sn Mössbauer spectroscopy in transmission (TMS) and emission (CEMS) modes confirms that ATCO is an amorphous Sn II composite oxide and shows that in the case of Sn 0.72[BPO 4] 0.28, the surface of the tin clusters is mainly formed by Sn II in an amorphous interface whereas the bulk of the clusters is mainly formed by Sn 0. The determination of the recoilless free fractions f (Lamb-Mössbauer factors) leads to the effective fraction of both Sn 0 and Sn II species in such composites. The influence of chemical composition and especially of the surface-to-bulk tin species ratio on the electrochemical behaviour has been analysed for several Sn x[BPO 4] 1-x composite materials (0.17< x<0.91). The cell using the compound Sn 0.72[BPO 4] 0.28 as active material exhibits interesting electrochemical performances (reversible capacity of 500 mAh g -1 at C/5 rate).

  7. Evaluation of commercial lithium-ion cells based on composite positive electrode for plug-in hybrid electric vehicle applications. Part I: Initial characterizations

    NASA Astrophysics Data System (ADS)

    Dubarry, Matthieu; Truchot, Cyril; Cugnet, Mikaël; Liaw, Bor Yann; Gering, Kevin; Sazhin, Sergiy; Jamison, David; Michelbacher, Christopher

    Evaluating commercial Li-ion batteries presents some unique benefits. One of them is to use cells made from established fabrication process and form factor, such as those offered by the 18650 cylindrical configuration, to provide a common platform to investigate and understand performance deficiency and aging mechanism of target chemistry. Such an approach shall afford us to derive relevant information without influence from processing or form factor variability that may skew our understanding on cell-level issues. A series of 1.9 Ah 18650 lithium ion cells developed by a commercial source using a composite positive electrode comprising {LiMn 1/3Ni 1/3Co 1/3O 2 + LiMn 2O 4} is being used as a platform for the investigation of certain key issues, particularly path-dependent aging and degradation in future plug-in hybrid electric vehicle (PHEV) applications, under the US Department of Energy's Applied Battery Research (ABR) program. Here we report in Part I the initial characterizations of the cell performance and Part II some aspects of cell degradation in 2C cycle aging. The initial characterizations, including cell-to-cell variability, are essential for life cycle performance characterization in the second part of the report when cell-aging phenomena are discussed. Due to the composite nature of the positive electrode, the features (or signature) derived from the incremental capacity (IC) of the cell appear rather complex. In this work, the method to index the observed IC peaks is discussed. Being able to index the IC signature in details is critical for analyzing and identifying degradation mechanism later in the cycle aging study.

  8. Transparent conducting oxide-free nitrogen-doped graphene/reduced hydroxylated carbon nanotube composite paper as flexible counter electrodes for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jindan; Yu, Mei; Li, Songmei; Meng, Yanbing; Wu, Xueke; Liu, Jianhua

    2016-12-01

    Three-dimensional nitrogen-doped graphene/reduced hydroxylated carbon nanotube composite aerogel (NG/CNT-OH) with unique hierarchical porosity and mechanical stability is developed through a two-step hydrothermal reaction. With plenty of exposed active sites and efficient multidimensional transport pathways of electrons and ions, NG/CNT-OH exhibits great electrocatalytic performances for I-/I3- redox couple. The subsequent compressed NG/CNT-OH papers possess high electrical conductivity and good flexibility, thus generating high-performance flexible counter electrodes (CEs) with transparent conducting oxide free (TCO-free) for dye-sensitized solar cells (DSSCs). The flexible NG/CNT-OH electrodes show good stability and the DSSCs with the optimized NG/CNT-OH CE had higher short-circuit current density (13.62 mA cm-2) and cell efficiency (6.36%) than DSSCs using Pt CE, whereas those of the DSSCs using Pt CE were only 12.81 mA cm-2 and 5.74%, respectively. Increasing the ratio of hydroxylated carbon nanotubes (CNT-OH) to the graphene oxide (GO) in the reactant would lead to less content of doped N, but better diffusion of electrolyte in the CEs because of more complete GO etching reaction. The design strategy presents a facile and cost effective way to synthesis three-dimensional graphene/CNT composite aerogel with excellent performance, and it can be potentially used as flexible TCO-free CE in other power conversion or energy storage devices.

  9. Electrochemical studies of thin films of conducting polymers and conducting polymer composites deposited on metal and semiconductor electrodes

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, G.; Di Stefano, S.; Moacanin, J.

    1987-01-01

    Electrochemical studies indicate that poly(Isothianaphthene) or PITN, can be p-doped only. Electrochemical properties of PITN and Nafion-PITN in acetonitrile solutions containing tetra-phenyl Phosphonium chloride as supporting electrolyte are compared. In both cases, the electrochemical behavior of thin films are different from that of thick films. In addition, Nafion does not seem to alter the electrochemical properties of PITN. Cyclic voltammetric and chronocoulometric measurements were made to compute the diffusion coefficient of the counter ions. Electrochemical behavior of both PITN and Nafion-PITN in acetonitrile solution containing different counter ions are described. PITN, when electrochemically deposited, apparently neither passivates surface states present nor forms ohmic contacts with p-Si or p(+)Si single-crystal electrodes.

  10. Performance study of magnesium-sulfur battery using a graphene based sulfur composite cathode electrode and a non-nucleophilic Mg electrolyte

    NASA Astrophysics Data System (ADS)

    Vinayan, B. P.; Zhao-Karger, Zhirong; Diemant, Thomas; Chakravadhanula, Venkata Sai Kiran; Schwarzburger, Nele I.; Cambaz, Musa Ali; Behm, R. Jürgen; Kübel, Christian; Fichtner, Maximilian

    2016-02-01

    Here we report for the first time the development of a Mg rechargeable battery using a graphene-sulfur nanocomposite as the cathode, a Mg-carbon composite as the anode and a non-nucleophilic Mg based complex in tetraglyme solvent as the electrolyte. The graphene-sulfur nanocomposites are prepared through a new pathway by the combination of thermal and chemical precipitation methods. The Mg/S cell delivers a higher reversible capacity (448 mA h g-1), a longer cyclability (236 mA h g-1 at the end of the 50th cycle) and a better rate capability than previously described cells. The dissolution of Mg polysulfides to the anode side was studied by X-ray photoelectron spectroscopy. The use of a graphene-sulfur composite cathode electrode, with the properties of a high surface area, a porous morphology, a very good electronic conductivity and the presence of oxygen functional groups, along with a non-nucleophilic Mg electrolyte gives an improved battery performance.Here we report for the first time the development of a Mg rechargeable battery using a graphene-sulfur nanocomposite as the cathode, a Mg-carbon composite as the anode and a non-nucleophilic Mg based complex in tetraglyme solvent as the electrolyte. The graphene-sulfur nanocomposites are prepared through a new pathway by the combination of thermal and chemical precipitation methods. The Mg/S cell delivers a higher reversible capacity (448 mA h g-1), a longer cyclability (236 mA h g-1 at the end of the 50th cycle) and a better rate capability than previously described cells. The dissolution of Mg polysulfides to the anode side was studied by X-ray photoelectron spectroscopy. The use of a graphene-sulfur composite cathode electrode, with the properties of a high surface area, a porous morphology, a very good electronic conductivity and the presence of oxygen functional groups, along with a non-nucleophilic Mg electrolyte gives an improved battery performance. Electronic supplementary information (ESI) available

  11. Fabrication of tin-cobalt/carbon composite electrodes by electrodeposition using cationic surfactant for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Lee, Cho-Long; Nam, Do-Hwan; Eom, Ji-Yong; Kwon, Hyuk-Sang

    2016-09-01

    Sn-Co alloy and Sn-Co/C composite are fabricated on the nodule-type Cu substrate by co-electrodeposition process using the pulse current in the pyrophosphate bath, and then their cycling performances are examined. To modify the surface property of carbon (acetylene black) particles and improve the dispersion of agglomerated carbon particles, CTAB (Cetrimonium bromide (C16H33)N(CH3)3Br) as a cationic surfactant is added into the electrodeposition bath.10.1007/s13391-016-6077-2 By addition of the CTAB, the amount of the carbon content in the Sn-Co/C composite is increased, and also the carbon particles are uniformly distributed in the Sn-Co electrodeposit. The Sn0.6Co0.4 alloy and (Sn0.6Co0.4)0.71/C0.29 composite are obtained after annealing as the final products. The (Sn0.6Co0.4)0.71/C0.29 composite anode exhibits better the capacity retention than the Sn0.6Co0.4 alloy anode due primarily to the role of the well-dispersed carbon particles as the second buffer phase and electrical conductive path in the Sn-Co/C composite during cycling.

  12. Liquid electrode

    DOEpatents

    Ekechukwu, Amy A.

    1994-01-01

    A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

  13. Synthesis and supercapacitor electrode of VO2(B)/C core-shell composites with a pseudocapacitance in aqueous solution

    NASA Astrophysics Data System (ADS)

    Zhang, Yifu; Zheng, Jiqi; Hu, Tao; Tian, Fuping; Meng, Changgong

    2016-05-01

    VO2(B)/C core-shell composites were successfully prepared using commercial V2O5, glucose and water as the starting materials by a facile one-pot hydrothermal method. The composition of the products was characterized by the techniques including X-ray powder diffraction, infrared spectroscopy, Raman, energy-dispersive X-ray spectrometer and elemental analysis. The morphology of the products was observed by scanning electron microscopy and transmission electron microscopy tests. The results showed the products consisted of the crystal VO2(B) phase and the amorphous carbon phase. The amorphous carbon contained lots of organic groups, such as sbnd OH, Csbnd H, Cdbnd O and Cdbnd C, etc., which suggested that the carbon here was organic carbon. The morphology of the as-obtained VO2(B)/C composites was well-defined nanobelts, and each VO2(B) core was encapsulated into carbon. Furthermore, the electrochemical properties of VO2(B)/C core-shell composites were investigated by cyclic voltammetry and galvanostatic charge-discharge. The results showed the measured capacitance of VO2(B)/C composites was mainly based on the pseudocapacitance. VO2(B)/C composites displayed the specific capacitance of 203, 190, 182, 173, 164, and 147 F g-1 at the current density of 0.2, 0.5, 1, 5, 10 and 20 A g-1, respectively. They also showed an excellent energy density of 198.9 W h kg-1 at a power density of 504.5 W kg-1 and a rapidly reversible redox Faraday response.

  14. Stretchable electronic skin based on silver nanowire composite fiber electrodes for sensing pressure, proximity, and multidirectional strain.

    PubMed

    Cheng, Yin; Wang, Ranran; Zhai, Haitao; Sun, Jing

    2017-03-17

    Electronic skin (E-skin) has been attracting great research interest and effort due to its potential applications in wearable health monitoring, smart prosthetics, robot skins and so on. To expand its applications, two key challenges lie in the realization of device stretchability, and independent sensing of pressure and multidirectional lateral strain. Here we made a combination of rational device structure and artfully engineered sensing materials to fulfill the mentioned demands. The as-prepared E-skin took a simple orthogonal configuration to enable both capacitive mode for pressure sensing and resistive mode for multidirectional strain sensing, independently. Pre-cracked silver nanowire based fibers with helical microstructures were utilized as basic electrodes to endow the E-skin with intrinsic stretchability and strain sensing capability. Through dielectric layer optimization, the pressure sensing sensitivity was greatly enhanced, with a detection limit of 1.5 Pa. For application demonstrations, we utilized the E-skin as both flat and curved platforms for pressure mapping, and also as human motion sensors, such as palm and thumb bending.

  15. Sensitive, simultaneous determination of chrysin and baicalein based on Ta2O5-chitosan composite modified carbon paste electrode.

    PubMed

    Xie, Zhengkun; Li, Gaiping; Fu, Yamin; Sun, Mengjiao; Ye, Baoxian

    2017-04-01

    Chrysin and baicalein are the major flavonoids found in oroxylum indicum, an essential herb in traditional Chinese medicine (TCM). Owing to their similar characteristics and physiochemical property, it is a great challenge to detect both of them simultaneously. In this work, tantalum oxide (Ta2O5) particles and chitosan modified carbon paste electrode (Ta2O5-CTS-CPE) was prepared and characterized by scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectrum(EIS). Under the optimum conditions, the prepared Ta2O5-CTS-CPE exhibited excellent electrocatalytic activity toward the oxidation of chrysin and baicalein, and it could serve as the sensor for highly sensitive and simultaneous determination both of them. The linear range is 0.08-4.0μM for both of them, and the detection limits were determined to be 0.03 and 0.05μM (S/N=3) for chrysin and baicalein, respectively. Furthermore, the proposed electrochemical sensor displayed high sensitivity, excellent stability and got satisfactory results in oroxylum indicum samples analysis.

  16. Electrocatalytical oxidation and sensitive determination of acetaminophen on glassy carbon electrode modified with graphene-chitosan composite.

    PubMed

    Zheng, Meixia; Gao, Feng; Wang, Qingxiang; Cai, Xili; Jiang, Shulian; Huang, Lizhang; Gao, Fei

    2013-04-01

    The electrochemical behaviors of acetaminophen (ACOP) on a graphene-chitosan (GR-CS) nanocomposite modified glassy carbon electrode (GCE) were investigated by cyclic voltammetry (CV), chronocoulometry (CC) and differential pulse voltammetry (DPV). Electrochemical characterization showed that the GR-CS nanocomposite had excellent electrocatalytic activity and surface area effect. As compared with bare GCE, the redox signal of ACOP on GR-CS/GCE was greatly enhanced. The values of electron transfer rate constant (ks), diffusion coefficient (D) and the surface adsorption amount (Γ(*)) of ACOP on GR-CS/GCE were determined to be 0.25s(-1), 3.61×10(-5) cm(2) s(-1) and 1.09×10(-9) mol cm(-2), respectively. Additionally, a 2e(-)/2H(+) electrochemical reaction mechanism of ACOP was deduced based on the acidity experiment. Under the optimized conditions, the ACOP could be quantified in the range from 1.0×10(-6) to 1.0×10(-4) M with a low detection limit of 3.0×10(-7) M based on 3S/N. The interference and recovery experiments further showed that the proposed method is acceptable for the determination of ACOP in real pharmaceutical preparations.

  17. Microwave-assisted synthesis of metal oxide/hydroxide composite electrodes for high power supercapacitors - A review

    NASA Astrophysics Data System (ADS)

    Faraji, Soheila; Ani, Farid Nasir

    2014-10-01

    Electrochemical capacitors (ECs), also known as pseudocapacitors or supercapacitors (SCs), is receiving great attention for its potential applications in electric and hybrid electric vehicles because of their ability to store energy, alongside with the advantage of delivering the stored energy much more rapidly than batteries, namely power density. To become primary devices for power supply, supercapacitors must be developed further to improve their ability to deliver high energy and power simultaneously. In this concern, a lot of effort is devoted to the investigation of pseudocapacitive transition-metal-based oxides/hydroxides such as ruthenium oxide, manganese oxide, cobalt oxide, nickel oxide, cobalt hydroxide, nickel hydroxide, and mixed metal oxides/hydroxides such as nickel cobaltite and nickel-cobalt oxy-hydroxides. This is mainly due to the fact that they can produce much higher specific capacitances than typical carbon-based electric double-layer capacitors and electronically conducting polymers. This review presents supercapacitor performance data of metal oxide thin film electrodes by microwave-assisted as an inexpensive, quick and versatile technique. Supercapacitors have established the specific capacitance (Cs) principles, therefore, it is likely that metal oxide films will continue to play a major role in supercapacitor technology and are expected to considerably increase the capabilities of these devices in near future.

  18. Paper microchip with a graphene-modified silver nano-composite electrode for electrical sensing of microbial pathogens.

    PubMed

    Safavieh, Mohammadali; Kaul, Vivasvat; Khetani, Sultan; Singh, Anupriya; Dhingra, Karan; Kanakasabapathy, Manoj Kumar; Draz, Mohamed Shehata; Memic, Adnan; Kuritzkes, Daniel R; Shafiee, Hadi

    2017-02-02

    Rapid and sensitive point-of-care diagnostics are of paramount importance for early detection of infectious diseases and timely initiation of treatment. Here, we present cellulose paper and flexible plastic chips with printed graphene-modified silver electrodes as universal point-of-care diagnostic tools for the rapid and sensitive detection of microbial pathogens or nucleic acids through utilizing electrical sensing modality and loop-mediated isothermal amplification (LAMP). We evaluated the ability of the developed paper-based assay to detect (i) viruses on cellulose-based paper microchips without implementing amplification in samples with viral loads between 10(6) and 10(8) copies per ml, and (ii) amplified HIV-1 nucleic acids in samples with viral loads between 10 fg μl(-1) and 10(8) fg μl(-1). The target HIV-1 nucleic acid was amplified using the RT-LAMP technique and detected through the electrical sensing of LAMP amplicons for a broad range of RNA concentrations between 10 fg μl(-1) and 10(8) fg μl(-1) after 40 min of amplification time. Our assay may be used for antiretroviral therapy monitoring where it meets the sensitivity requirement of the World Health Organization guidelines. Such a paper microchip assay without the amplification step may also be considered as a simple and inexpensive approach for acute HIV detection where maximum viral replication occurs.

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

    PubMed

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

    2015-09-16

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

  20. Enhancement of Electrode Stability Using Platinum-Cobalt Nanocrystals on a Novel Composite SiCTiC Support.

    PubMed

    Millán, María; Zamora, Héctor; Rodrigo, Manuel A; Lobato, Justo

    2017-02-22

    PtCo alloy catalysts for high temperature PEMFCs (protonic exchange membrane fuel cells) were synthesized on a novel noncarbonaceous support (SiCTiC) using the impregnation method with NaBH4 as the reducing agent at different synthesis temperatures to evaluate the effect of this variable on their physicochemical and electrochemical properties. The catalysts were characterized by inductively coupled plasma optical emission spectrometry, scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscope-energy dispersive X-ray,and temperature-programmed reduction. In addition, the electrochemical characterization (i.e., cyclic voltammetry, oxygen reduction reaction, and chronoamperometry) was carried out with a rotating disk electrode. For the cyclic voltammetry investigation, 400 cycles were performed in hot phosphoric acid and a half-cell to evaluate the stability of the synthesized catalysts. The catalyst synthesized on SiCTiC exhibited excellent durability compared to the catalyst synthesized on a Vulcan support. In addition, all synthesized catalysts exhibited better catalytic activity than that of the PtCo/C catalysts. The best results were observed for the catalyst synthesized at 80 °C due to its shorter Pt-Pt nearest-neighbor and higher alloy degree. Finally, a preliminary stability test was conducted in an HT-PEMFC, and promising results in terms of stability and performance were observed.

  1. One-pot synthesis of platinum-based nanoparticles incorporated into mesoporous niobium oxide-carbon composites for fuel cell electrodes.

    PubMed

    Orilall, M Christopher; Matsumoto, Futoshi; Zhou, Qin; Sai, Hiroaki; Abruña, Héctor D; DiSalvo, Francis J; Wiesner, Ulrich

    2009-07-08

    Catalyst-electrode design is crucial for the commercialization and widespread use of polymer electrolyte membrane fuel cells. There are considerable challenges in making less expensive, more durable, and more active catalysts. Herein, we report the one-pot synthesis of Pt and Pt-Pb nanoparticles incorporated into the pores of mesoporous niobium oxide-carbon composites. The self-assembly of block copolymers with niobium oxide and metal precursors results in an ordered mesostructured hybrid. Appropriate heat treatment of this hybrid produces highly crystalline, well-ordered mesoporous niobium oxide-carbon composites with Pt (or Pt-Pb) nanoparticles incorporated into the mesopores. The in situ-generated graphitic-like carbon material prevents the collapse of the mesostructure, while the metal oxide crystallizes at high temperatures and enhances the electrical conductivity of the final material. Formic acid electrooxidation with this novel material shows 4 times higher mass activities (3.3 mA/microg) and somewhat lower onset potentials (-0.24 V vs Ag/AgCl) than the best previously reported values employing Pt-Pb intermetallic nanoparticles supported on conducting carbon (0.85 mA/microg and -0.18 V, respectively).

  2. Silver decorated LaMnO3 nanorod/graphene composite electrocatalysts as reversible metal-air battery electrodes

    NASA Astrophysics Data System (ADS)

    Hu, Jie; Liu, Qiunan; Shi, Lina; Shi, Ziwei; Huang, Hao

    2017-04-01

    Perovskite LaMnO3 nanorod/reduced graphene oxides (LMO-NR/RGO) decorated with Ag nanoparticles are studied as a bifunctional catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline electrolyte. LMO-NR/RGO composites are synthesized by using cetyltrimethyl ammonium bromide (CTAB) as template via a simple hydrothermal reaction followed by heat treatment; overlaying of Ag nanoparticles is obtained through a traditional silver mirror reaction. Electron microscopy reveals that LMO-NR is embedded between the sheets of RGO, and the material is homogeneously overlaid with Ag nanoparticles. The unique composite morphology of Ag/LMO-NR/RGO not only enhances the electron transport property by increasing conductivity but also facilitates the diffusion of electrolytes and oxygen. As confirmed by electrochemical testing, Ag/LMO-NR/RGO exhibits very strong synergy with Ag nanoparticles, LMO-NR, and RGO, and the catalytic activities of Ag/LMO-NR/RGO during ORR and OER are significantly improved. With the novel catalyst, the homemade zinc-air battery can be reversibly charged and discharged and display a stable cycle performance, indicating the great potential of this composite as an efficient bifunctional electrocatalyst for metal-air batteries.

  3. Simultaneous Stripping Detection of Pb(II), Cd(II) and Zn(II) Using a Bimetallic Hg-Bi/Single-Walled Carbon Nanotubes Composite Electrode

    PubMed Central

    Ouyang, Ruizhuo; Zhu, Zhenqian; Tatum, Clarissa E.; Chambers, James Q.; Xue, Zi-Ling

    2011-01-01

    A new, sensitive platform for the simultaneous electrochemical assay of Zn(II), Cd(II) and Pb(II) in aqueous solution has been developed. The platform is based on a new bimetallic Hg-Bi/single-walled carbon nanotubes (SWNTs) composite modified glassy carbon electrode (GCE), demonstrating remarkably improved performance for the anodic stripping assay of Zn(II), Cd(II) and Pb(II). The synergistic effect of Hg and Bi as well as the enlarged, activated surface and good electrical conductivity of SWNTs on GCE contribute to the enhanced activity of the proposed electrode. The analytical curves for Zn(II), Cd(II) an Pb(II) cover two linear ranges varying from 0.5 to 11 μg L-1 and 10 to 130 μg L-1 with correlation coefficients higher than 0.992. The limits of detection for Zn(II), Cd(II) are lower than 2 μg L-1 (S/N = 3). For Pb(II), moreover, there is another lower, linear range from 5 to 1100 ng L-1 with a coefficient of 0.987 and a detection limit of 0.12 ng L-1. By using the standard addition method, Zn(II), Cd(II) and Pb(II) ions in river samples were successfully determined. These results suggest that the proposed method can be applied as a simple, efficient alternative for the simultaneous monitoring of heavy metals in water samples. In addition, this method demonstrates the powerful application of carbon nanotubes in electrochemical analysis of heavy metals. PMID:21660117

  4. Enhanced electrodes for solid state gas sensors

    DOEpatents

    Garzon, Fernando H.; Brosha, Eric L.

    2001-01-01

    A solid state gas sensor generates an electrical potential between an equilibrium electrode and a second electrode indicative of a gas to be sensed. A solid electrolyte substrate has the second electrode mounted on a first portion of the electrolyte substrate and a composite equilibrium electrode including conterminous transition metal oxide and Pt components mounted on a second portion of the electrolyte substrate. The composite equilibrium electrode and the second electrode are electrically connected to generate an electrical potential indicative of the gas that is being sensed. In a particular embodiment of the present invention, the second electrode is a reference electrode that is exposed to a reference oxygen gas mixture so that the electrical potential is indicative of the oxygen in a gas stream.

  5. Synthesis and characterization of α-MoO{sub 3} nanobelt composite positive electrode materials for lithium battery application

    SciTech Connect

    Nadimicherla, Reddeppa; Chen, Wen; Guo, Xin

    2015-06-15

    Graphical abstract: (a) TEM image of MoO{sub 3}/PEO nanobelts composite, (b) CV curves of MoO{sub 3}/PEO nanobelts composite. - Highlights: • α-MoO{sub 3} and PEO surfactant MoO{sub 3} nanobelts were synthesized by solvothermal method. • The capacity retention of 12.5 wt% PEO surfactant MoO{sub 3} nanobelts is 88.78%. • The specific capacity of 12.5 wt% PEO surfactant MoO{sub 3} nanobelts is 352 mAh g{sup −1}. • MoO{sub 3}/PEO nanobelts composite material demonstrates good cycling stability as cathode. - Abstract: α-MoO{sub 3} and PEO surfactant MoO{sub 3} nanobelts were synthesized by a solvothermal method. The morphology and nanostructure of samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Bare α-MoO{sub 3} and 12.5 wt% PEO surfactant MoO{sub 3} nanobelts have an initial specific capacities of 279 and 352 mAh g{sup −1}, respectively, at constant current density 30 mA g{sup −1} with potential range of 1.5–4.0 V vs. Li/Li{sup +}. While MoO{sub 3} is modified by the intercalation of PEO, it is effectively shielded against electrostatic interaction between the MoO{sub 3} interlayer and Li{sup +} ions. We reported positive material, a nanocomposite of MoO{sub 3} coated with polyethylene oxide. It presents good cycling stability due to existence of the conductive and protective polyethylene oxide coating and the nanobelt morphology of MoO{sub 3}. The polyethylene oxide acts as a conducting matrix, a binder and an active material, as well as a volume change buffer agent, which holds the MoO{sub 3} particles in place during the discharge cycles. The cyclic voltammograms of the 12.5 wt% PEO surfactant MoO{sub 3} nanobelt composite displayed better cyclic performance compared with pure MoO{sub 3} nanobelts. The specific capacity of the pure MoO{sub 3} nanobelts and 12.5 wt% PEO surfactant MoO{sub 3

  6. The effect of electrolyte composition on the electroreduction of CO2 to CO on Ag based gas diffusion electrodes.

    PubMed

    Verma, Sumit; Lu, Xun; Ma, Sichao; Masel, Richard I; Kenis, Paul J A

    2016-03-14

    The electroreduction of CO2 to C1-C2 chemicals can be a potential strategy for utilizing CO2 as a carbon feedstock. In this work, we investigate the effect of electrolytes on the electroreduction of CO2 to CO on Ag based gas diffusion electrodes. Electrolyte concentration was found to play a major role in the process for the electrolytes (KOH, KCl, and KHCO3) studied here. Several fold improvements in partial current densities of CO (jCO) were observed on moving from 0.5 M to 3.0 M electrolyte solution independent of the nature of the anion. jCO values as high as 440 mA cm(-2) with an energy efficiency (EE) of ≈ 42% and 230 mA cm(-2) with EE ≈ 54% were observed when using 3.0 M KOH. Electrochemical impedance spectroscopy showed that both the charge transfer resistance (Rct) and the cell resistance (Rcell) decreased on moving from a 0.5 M to a 3.0 M KOH electrolyte. Anions were found to play an important role with respect to reducing the onset potential of CO in the order OH(-) (-0.13 V vs. RHE) < HCO3(-) (-0.46 V vs. RHE) < Cl(-) (-0.60 V vs. RHE). A decrease in Rct upon increasing electrolyte concentration and the effect of anions on the cathode can be explained by an interplay of different interactions in the electrical double layer that can either stabilize or destabilize the rate limiting CO2˙(-) radical. EMIM based ionic liquids and 1 : 2 choline Cl urea based deep eutectic solvents (DESs) have been used for CO2 capture but exhibit low conductivity. Here, we investigate if the addition of KCl to such solutions can improve conductivity and hence jCO. Electrolytes containing KCl in combination with EMIM Cl, choline Cl, or DESs showed a two to three fold improvement in jCO in comparison to those without KCl. Using such mixtures can be a strategy for integrating the process of CO2 capture with CO2 conversion.

  7. Liquid electrode

    DOEpatents

    Ekechukwu, A.A.

    1994-07-05

    A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

  8. Simultaneous Determination of Uric Acid and Xanthine Using a Poly(Methylene Blue) and Electrochemically Reduced Graphene Oxide Composite Film Modified Electrode

    PubMed Central

    Liu, Gen; Ma, Wei; Luo, Yan; Sun, Deng-ming; Shao, Shuang

    2014-01-01

    Poly(methylene blue) and electrochemically reduced graphene oxide composite film modified electrode (PMB-ERGO/GCE) was successfully fabricated by electropolymerization and was used for simultaneous determination of uric acid (UA) and xanthine (Xa). Based on the excellent electrocatalytic activity of PMB-ERGO/GCE, the electrochemical behaviors of UA and Xa were studied by cyclic voltammetry (CV) and square wave voltammetry (SWV). Two anodic sensitive peaks at 0.630 V (versus Ag/AgCl) for UA and 1.006 V (versus Ag/AgCl) for Xa were given by CV in pH 3.0 phosphate buffer. The calibration curves for UA and Xa were obtained in the range of 8.00 × 10−8~4.00 × 10−4 M and 1.00 × 10−7~4.00 × 10−4 M, respectively, by SWV. The detection limits for UA and Xa were 3.00 × 10−8 M and 5.00 × 10−8 M, respectively. Finally, the proposed method was applied to simultaneously determine UA and Xa in human urine with good selectivity and high sensitivity. PMID:25436174

  9. Flexible carbon nanotube/polypropylene composite plate decorated with poly(3,4-ethylenedioxythiophene) as efficient counter electrodes for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Lin, Jeng-Yu; Wang, Wei-Yen; Chou, Shu-Wei

    2015-05-01

    In this study, we fabricate an efficient, flexible and low-cost counter electrode (CE) composed of a plasma-etched carbon nanotubes/polypropylene (designated as ECP) composite plate decorated with poly(3,4-ethylene dioxythiophene) (PEDOT) for dye-sensitized solar cells (DSCs). The PEDOT-decorated monolithic ECP CEs are fabricated via series of processes including high-temperature refluxing, thermal compression, oxygen plasma etching, and electropolymerization. The bottom ECP plate is used to replace conventional transparent conducting oxide (TCO) as a conductive substrate, and the top PEDOT layer is employed as catalyst for I3- reduction. According to the extensive electrochemical measurements, the as-fabricated flexible PEDOT coated ECP CE demonstrates a Pt-like electrocatalytic for I3- reduction. The DSC based on the flexible PEDOT-decorated ECP CE yields impressive energy conversion efficiency of 6.82% (or 6.77% even after the bending test), which is comparable to that of the DSC using the Pt CE (7.20%) under similar device architecture conditions. Therefore, the PEDOT-decorated ECP based CEs show the possibility of serving as low-cost and flexible CEs for efficient DSCs.

  10. Composite films of metal doped CoS/carbon allotropes; efficient electrocatalyst counter electrodes for high performance quantum dot-sensitized solar cells.

    PubMed

    Khalili, Seyede Sara; Dehghani, Hossein; Afrooz, Malihe

    2017-05-01

    This study reports the enhanced catalytic ability of metal ions-doped CoS and CoS/carbon allotrope counter electrodes (CEs) (synthesized using a successive ionic layer adsorption and reaction (SILAR) method) to improve the power conversion efficiency (η) in quantum dot-sensitized solar cells (QDSSCs). Firstly, doping effects of different metal ions (Mg(2+), Ca(2+), Sr(2+) and Ba(2+)) in the CoS CE on the QDSSCs performance have been investigated. Overall, among the different metal doped CoS CEs, the best energy conversion efficiency of 2.19%, achieved for Sr, is the highest reported for QDSSCs constructed with metal doped CoS. A sandwich structural Sr- and Ba-CoS/carbon allotrope (graphene sheet (GS), graphene oxide (GO) and carbon nanotube (CNT)) composite CEs have been prepared by repeating electrophoretic deposition (EPD) of carbon materials and deposition of CoS nanoparticles. Dramatic enhancements of η have been observed with the Sr- and Ba-CoS/GO CEs based QDSSCs (∼76% and ∼41%, respectively), which is higher than that of the bare CoS CE. Because of the large specific surface area and superior electrical conductivity of GS, GO and CNT and the high electrocatalytic activity of CoS, these CEs show an improvement in the photocurrent density in the cells, as revealed from electrochemical and spectral data.

  11. Removal of caffeine from aqueous solution by indirect electrochemical oxidation using a graphite-PVC composite electrode: A role of hypochlorite ion as an oxidising agent.

    PubMed

    Al-Qaim, Fouad F; Mussa, Zainab H; Othman, Mohamed R; Abdullah, Md P

    2015-12-30

    The electrochemical oxidation of caffeine, a widely over-the-counter stimulant drug, has been investigated in effluent wastewater and deionized water (DIW) using graphite-poly vinyl chloride (PVC) composite electrode as anode. Effects of initial concentration of caffeine, chloride ion (Cl(-)) loading, presence of hydrogen peroxide (H2O2), sample volume, type of sample and applied voltage were determined to test and to validate a kinetic model for the oxidation of caffeine by the electrochemical oxidation process. The results revealed that the electrochemical oxidation rates of caffeine followed pseudo first-order kinetics, with rate constant values ranged from 0.006 to 0.23 min(-1) depending on the operating parameters. The removal efficiency of caffeine increases with applied voltage very significantly, suggesting a very important role of mediated oxidation process. However, the consumption energy was considered during electrochemical oxidation process. In chloride media, removal of caffeine is faster and more efficiently, although occurrence of more intermediates takes place. The study found that the adding H2O2 to the NaCl solution will inhibit slightly the electrochemical oxidation rate in comparison with only NaCl in solution. Liquid chromatography-time of flight-mass spectrometry (LC-TOF-MS) technique was applied to the identification of the by-products generated during electrochemical oxidation, which allowed to construct the proposed structure of by-products.

  12. Sensitive HIV-1 detection in a homogeneous solution based on an electrochemical molecular beacon coupled with a nafion-graphene composite film modified screen-printed carbon electrode.

    PubMed

    Li, Bo; Li, Zhengliang; Situ, Bo; Dai, Zong; Liu, Qinlan; Wang, Qian; Gu, Dayong; Zheng, Lei

    2014-02-15

    A novel electrochemical sensing assay for sensitive determination of HIV-1 in a homogeneous solution has been developed using an electrochemical molecular beacon combined with a nafion-graphene composite film modified screen-printed carbon electrode (nafion-graphene/SPCE). The electrochemical molecular beacon (CAs-MB), comprising a special recognition sequence for the conserved region of the HIV-1 gag gene and a pair of carminic acid molecules as a marker, can indicate the presence of the HIV-1 target by its on/off electrochemical signal behavior. It is suitable for direct, electrochemical determination of HIV-1, thereby simplifying the detection procedure and improving the signal-to-noise (S/N) ratio. To further improve the sensitivity, the nafion-graphene/SPCE was used to monitor changes in the CAs-MB, which has notable advantages, such as being ultrasensitive, inexpensive, and disposable. Under optimized conditions, the peak currents showed a linear relationship with the logarithm of target oligonucleotide concentrations ranging from 40 nM to 2.56 μM, with a detection limit of 5 nM (S/N=3). This sensing assay also displays a good stability, with a recovery of 88-106.8% and RSD<7% (n=5) in real serum samples. This work may lead to the development of an effective method for early point-of-care diagnosis of HIV-1 infection.

  13. One-step solvothermal tailoring the compositions and phases of nickel cobalt sulfides on conducting oxide substrates as counter electrodes for efficient dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Huang, Niu; Li, Guowang; Huang, Hua; Sun, Panpan; Xiong, Tianli; Xia, Zhifen; Zheng, Fang; Xu, Jixing; Sun, Xiaohua

    2016-12-01

    Several nickel cobalt sulfide (Ni-Co-S) counter electrodes (CEs) are prepared, and the Ni-Co-S nanoparticles are in-situ grown on SnO2: F (FTO) transparent conductive glasses via a facile solvothermal process, in which thiourea is used as the sulfurizing reagent. The X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometer are employed to measure the microstructure and composition of the Ni-Co-S CEs. When a proper amount of thiourea is adopted, fine crystalline NiCo2S4 CE is obtained. When the amount of thiourea is small or large, (Ni,Co)4S3 or (Ni,Co)3S4 CE is acquired, respectively. Cyclic voltammetry, electrochemical impedance spectroscopy, Tafel polarization and open-circuit voltage decay (OCVD) measurements all demonstrate that the electrocatalytic activities and electrical conductivities of these Ni-Co-S CEs all approach or exceed those of Pt-pyrolysis CE. Their superior electrochemical performances are further confirmed by fabricating DSSCs with the Ni-Co-S CEs, they display similar or better photo-electric conversion efficiencies to/than the Pt-pyrolysis counterpart.

  14. A molecularly-imprinted electrochemical sensor based on a graphene-Prussian blue composite-modified glassy carbon electrode for the detection of butylated hydroxyanisole in foodstuffs.

    PubMed

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

    2013-10-21

    In this study, we developed a novel molecularly-imprinted electrochemical sensor based on a glassy carbon electrode (GCE) decorated by graphene-Prussian blue (GR-PB) composites for the selective and sensitive determination of butylated hydroxyanisole (BHA). The molecularly-imprinted polymers (MIPs) were synthesized by BHA and pyrrole as the template molecule and functional monomer, respectively. Also, the MIPs were assembled on the surface of the GR-PB/GCE by electropolymerization. The sensor was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and chronoamperometry. It was confirmed that the synergistic effects of GR and PB could improve the electrochemical response and the sensitivity of the sensor. The linear range of the sensor was from 9 × 10(-8) mol L(-1) to 7 × 10(-5) mol L(-1), with a limit of detection (LOD) of 7.63 × 10(-8) mol L(-1) (S/N = 3). The proposed sensor displayed high selectivity, excellent stability and good reproducibility for the determination of BHA. It was successfully applied to the determination of BHA in real samples.

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

    PubMed

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

    2013-06-15

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

  16. Studies on graphene enfolded olivine composite electrode material via polyol technique for high rate performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Muruganantham, Rasu; Sivakumar, Marimuthu; Subadevi, Rengapillai; Ramaprabhu, Sundara; Wu, Nae-Lih

    2015-09-01

    The graphene enfolded LiFePO4/C composite cathode material has been prepared via low temperature polyol process, followed by a simple chemical reaction method. The low viscous polyol solvent (DEG) (35.7 mPa s at 25°C) and usage of low temperature process (below 245°C) aid the graphene tightly encapsulated on the LiFePO4 surface that plays an important role, especially in the high rate performances over long cycles, efficiently preventing the separation of the graphene and LiFePO4 during the reaction processes, hence realizing the full potential of the active materials. The graphitization on LiFePO4/C remarkably increased the electronic conductivity of LiFePO4. The layered sheets of graphene wrapped on LiFePO4 particles provide void between graphene sheets and LiFePO4 surfaces, which facilitate the diffusion of Li+. This approach opens up a method to attain the theoretical capacity of LiFePO4. The material exhibits a superior electrochemical performance such as initial discharge capacities of 169.6 and 92 mAhg-1 at 0.1 and 30 C rates, respectively. It has an excellent capacity retention and diminutive capacity fading. The nanosize of LiFePO4 particle causes a shorter diffusion path, which reduces the time for Li+ migration between cathode and electrolyte. [Figure not available: see fulltext.

  17. Production of composite Si nanoparticles by plasma spraying PVD and CH4 annealing for negative electrodes of lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Ohta, Ryoshi; Ohta, Yutaro; Tashiro, Toru; Kambara, Makoto

    2015-09-01

    Si is a promising candidate as anode of next generation high density Li ion batteries. This material, however, needs to be nanostructured, nanoparticles and C coating of active material, to cope with huge volume change and associated rapid capacity decay. Si nanoparticles with 20-40 nm have been successfully produced by plasma spraying PVD and also Si-C core-shell composite particles by adding CH4 during processing. The battery performance has been improved with these nanopowders as anode, especially with the C coated Si particles. However, SiC that is inactive in battery reaction forms inevitably at high temperature during plasma spraying PVD and reduces the capacity density. In this work, therefore, post CH4 annealing was attempted to form Si-C nanocomposite particles while suppressing formation of SiC. The primary Si nanoparticles were unchanged in size after annealing and were coated with the finer carbonous particles that formed after CH4 infiltration through pores between nanoparticles. The batteries using annealed powders with C/Si molar ratio of 0.3 have shown two-fold capacity retention increase after 50 cycles with no capacity reduction associated with SiC formation as compared to the powders without C. This work was partly supported by the Funding Program for Next Generation World-Leading Researchers (NEXT Program) of Japan.

  18. Polystyrene-Templated Aerosol Synthesis of MoS2 -Amorphous Carbon Composite with Open Macropores as Battery Electrode.

    PubMed

    Choi, Seung Ho; Kang, Yun Chan

    2015-07-08

    MoS2 -amorphous carbon (MoS2 -AC) composite microspheres with macroporous structure were fabricated by one-pot spray pyrolysis. Single- or few-layered MoS2 were uniformly dispersed and oriented in random directions in the amorphous carbon microsphere with macropores sizes between 50 and 90 nm. The macroporous microspheres having a high contact area with liquid electrolyte exhibited overall superior Li- and Na-ion storage properties compared with those of the dense microspheres. After 250 charge/discharge cycles at a current density of 1.5 A g(-1) , the discharge capacities of the MoS2 -AC microspheres with dense and macroporous structures for Li-ion storage were 694 and 896 mAh g(-1) , respectively. In the case of Na-ion storage, discharge capacities of 336 and 425 mAh g(-1) were achieved for the dense and macroporous microspheres, respectively, after 100 cycles at 0.3 A g(-1) .

  19. Catalyzed enzyme electrodes

    DOEpatents

    Zawodzinski, Thomas A.; Wilson, Mahlon S.; Rishpon, Judith; Gottesfeld, Shimshon

    1993-01-01

    An enzyme electrode is prepared with a composite coating on an electrical conductor. The composite coating is formed from a casting solution of a perfluorosulfonic acid polymer, an enzyme, and a carbon supported catalyst. The solution may be cast directly on the conductor surface or may be formed as a membrane and applied to the surface. The perfluorosulfonic acid ionomer formed from the casting solution provides an insoluble biocompatible protective matrix for the enzyme and acts to retain the enzyme for long term availability in the electrode structure. The carbon supported catalyst provides catalytic sites throughout the layer for the oxidation of hydrogen peroxide from the enzyme reactions. The carbon support then provides a conductive path for establishing an electrical signal to the electrical conductor. In one embodiment, the electrical conductor is a carbon cloth that permits oxygen or other gas to be introduced to the perfluorosulfonic polymer to promote the enzyme reaction independent of oxygen in the solution being tested.

  20. Electrode for a lithium cell

    DOEpatents

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

    2008-10-14

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

  1. Magnetohydrodynamic electrode

    DOEpatents

    Marchant, David D.; Killpatrick, Don H.

    1978-01-01

    An electrode capable of withstanding high temperatures and suitable for use as a current collector in the channel of a magnetohydrodynamic (MHD) generator consists of a sintered powdered metal base portion, the upper surface of the base being coated with a first layer of nickel aluminide, an intermediate layer of a mixture of nickel aluminide - refractory ceramic on the first layer and a third or outer layer of a refractory ceramic material on the intermediate layer. The sintered powdered metal base resists spalling by the ceramic coatings and permits greater electrode compliance to thermal shock. The density of the powdered metal base can be varied to allow optimization of the thermal conductivity of the electrode and prevent excess heat loss from the channel.

  2. Cermet electrode

    DOEpatents

    Maskalick, Nicholas J.

    1988-08-30

    Disclosed is a cermet electrode consisting of metal particles of nickel, cobalt, iron, or alloys or mixtures thereof immobilized by zirconia stabilized in cubic form which contains discrete deposits of about 0.1 to about 5% by weight of praseodymium, dysprosium, terbium, or a mixture thereof. The solid oxide electrode can be made by covering a substrate with particles of nickel, cobalt, iron, or mixtures thereof, growing a stabilized zirconia solid oxide skeleton around the particles thereby immobilizing them, contacting the skeleton with a compound of praseodymium, dysprosium, terbium, or a mixture thereof, and heating the skeleton to a temperature of at least 500.degree. C. The electrode can also be made by preparing a slurry of nickel, cobalt, iron, or mixture and a compound of praseodymium, dysprosium, terbium, or a mixture thereof, depositing the slurry on a substrate, heating the slurry to dryness, and growing a stabilized zirconia skeleton around the metal particles.

  3. Photoelectrochemical electrodes

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Rembaum, A. (Inventor)

    1983-01-01

    The surface of a moderate band gap semiconductor such as p-type molybdenum sulfide is modified to contain an adherent film of charge mediating ionene polymer containing an electroactive unit such as bipyridimium. Electron transport between the electrode and the mediator film is favorable and photocorrosion and recombination processes are suppressed. Incorporation of particles of catalyst such as platinum within the film provides a reduction in overvoltage. The polymer film is readily deposited on the electrode surface and can be rendered stable by ionic or addition crosslinking. Catalyst can be predispersed in the polymer film or a salt can be impregnated into the film and reduced therein.

  4. Ceramic component for electrodes

    DOEpatents

    Marchant, David D.; Bates, J. Lambert

    1980-01-01

    A ceramic component suitable for preparing MHD generator electrodes having the compositional formula: Y.sub.x (Mg.sub.y Cr.sub.z).sub.w Al.sub.(1-w) O.sub.3 where x=0.9 to 1.05, y=0.02 to 0.2, z=0.8 to 1.05 and w=1.0 to 0.5. The component is resistant to the formation of hydration products in an MHD environment, has good electrical conductivity and exhibits a lower electrochemical corrosion rate than do comparable compositions of lanthanum chromite.

  5. A microwave synthesized CuxS and graphene oxide nanoribbon composite as a highly efficient counter electrode for quantum dot sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Ghosh, Dibyendu; Halder, Ganga; Sahasrabudhe, Atharva; Bhattacharyya, Sayan

    2016-05-01

    To boost the photoconversion efficiency (PCE) of ever promising quantum dot sensitized solar cells (QDSSCs), and to improve the design of photoanodes, the ability of the counter electrode (CE) to effectively reduce the oxidized electrolyte needs special attention. A composite of a 15 wt% graphene oxide nanoribbon (GOR), obtained by unzipping multi-walled carbon nanotubes (MWCNTs), and CuxS intersecting hexagonal nanoplates, synthesized by a low cost, facile and scalable microwave synthesis route, is reported as a fascinating CE for QDSSCs. The best performing Cu1.18S-GOR CE could notably achieve a record PCE of ~3.55% for CdS sensitized QDSSCs, ~5.42% for in situ deposited CdS/CdSe co-sensitized QDSSCs and ~6.81% for CdTe/CdS/CdS dual sensitized QDSSCs, apart from increasing the PCE of previously reported QDSSCs. A systematic investigation of the CE design revealed the high electrocatalytic activity of GOR due to the presence of organic functional groups, graphitic edge sites and a quasi-one-dimensional (quasi-1D) structure, which increases the interfacial charge transfer kinetics from the CE to the polysulfide electrolyte. The highly stable Cu1.18S-GOR CE has the added advantage of a favourable energy band alignment with the redox potential of the polysulfide electrolyte, which reduces the loss of charge carriers and thus can increase the PCE of QDSSCs.To boost the photoconversion efficiency (PCE) of ever promising quantum dot sensitized solar cells (QDSSCs), and to improve the design of photoanodes, the ability of the counter electrode (CE) to effectively reduce the oxidized electrolyte needs special attention. A composite of a 15 wt% graphene oxide nanoribbon (GOR), obtained by unzipping multi-walled carbon nanotubes (MWCNTs), and CuxS intersecting hexagonal nanoplates, synthesized by a low cost, facile and scalable microwave synthesis route, is reported as a fascinating CE for QDSSCs. The best performing Cu1.18S-GOR CE could notably achieve a record PCE of ~3

  6. Analysis of SOFCs Using Reference Electrodes

    SciTech Connect

    Finklea, H.; Chen, X.; Gerdes, K.; Pakalapati, S.; Celik, I.

    2013-01-01

    Reference electrodes are frequently applied to isolate the performance of one electrode in a solid oxide fuel cell. However, reference electrode simulations raise doubt to veracity of data collected using reference electrodes. The simulations predict that the reported performance for the one electrode will frequently contain performance of both electrodes. Nonetheless, recent reports persistently treat data so collected as ideally isolated. This work confirms the predictions of the reference electrode simulations on two SOFC designs, and to provides a method of validating the data measured in the 3-electrode configuration. Validation is based on the assumption that a change in gas composition to one electrode does not affect the impedance of the other electrode at open circuit voltage. This assumption is supported by a full physics simulation of the SOFC. Three configurations of reference electrode and cell design are experimentally examined using various gas flows and two temperatures. Impedance data are subjected to deconvolution analysis and equivalent circuit fitting and approximate polarization resistances of the cathode and anode are determined. The results demonstrate that the utility of reference electrodes is limited and often wholly inappropriate. Reported impedances and single electrode polarization values must be scrutinized on this basis.

  7. Microvoltammetric Electrodes.

    DTIC Science & Technology

    1985-09-25

    Microvoltammetric Electrodes, J. 0. Howell, R. M. Wightman, Anal. Chem., 56, 524-529 (1984). 2. Flow Rate Independent Amperometric Cell , W. L. Caudill...Electroanal. Chem., 182, 113-122 (1985). C. List of all publications 1. Flow Rate Independent Amperometric Cell , W. L. Caudill, J. 0. Howell, R. M

  8. Advanced membrane electrode assemblies for fuel cells

    SciTech Connect

    Kim, Yu Seung; Pivovar, Bryan S

    2014-02-25

    A method of preparing advanced membrane electrode assemblies (MEA) for use in fuel cells. A base polymer is selected for a base membrane. An electrode composition is selected to optimize properties exhibited by the membrane electrode assembly based on the selection of the base polymer. A property-tuning coating layer composition is selected based on compatibility with the base polymer and the electrode composition. A solvent is selected based on the interaction of the solvent with the base polymer and the property-tuning coating layer composition. The MEA is assembled by preparing the base membrane and then applying the property-tuning coating layer to form a composite membrane. Finally, a catalyst is applied to the composite membrane.

  9. Advanced membrane electrode assemblies for fuel cells

    SciTech Connect

    Kim, Yu Seung; Pivovar, Bryan S.

    2012-07-24

    A method of preparing advanced membrane electrode assemblies (MEA) for use in fuel cells. A base polymer is selected for a base membrane. An electrode composition is selected to optimize properties exhibited by the membrane electrode assembly based on the selection of the base polymer. A property-tuning coating layer composition is selected based on compatibility with the base polymer and the electrode composition. A solvent is selected based on the interaction of the solvent with the base polymer and the property-tuning coating layer composition. The MEA is assembled by preparing the base membrane and then applying the property-tuning coating layer to form a composite membrane. Finally, a catalyst is applied to the composite membrane.

  10. Solid-contact Hg(II)-selective electrode based on a carbon-epoxy composite containing a new dithiophosphate-based ionophore.

    PubMed

    Juarez-Gomez, J; Perez-Garcia, F; Ramirez-Silva, M T; Rojas-Hernandez, A; Galan-Vidal, C A; Paez-Hernandez, M E

    2013-09-30

    The experimental results herein concern a novel ion-selective electrode manufactured with an inner solid contact based on a new ligand O,O'-(2,2'-biphenylene)dithiophosphate pentyl (PenDTF). This electrode displays high selectivity toward the Hg(II) ion even in the presence of different divalent ions. The electrode also exhibited a good Nernstian response to Hg(II) (33.7±1.0 mV decade(-1)) over an ample concentration range (5.3×10(-7)-1.0×10(-2) mol L(-1)), with a detection limit of (6.1±1.7)×10(-7) mol L(-1). As a result of design, the electrode can be used for many experiments, simply renewing its contact surface with emery paper, without giving rise to a significant response deviation, exhibiting a variation coefficient of 3%, capable of being tested within the 0-5 pH interval. The electrode was used satisfactorily as indicating electrode during the potentiometric titration of Hg(II) ions with EDTA.

  11. Influence of the composition and crystalline phase of electrodeposited CoNi films in the preparation of CoNi oxidized surfaces as electrodes for urea electro-oxidation

    NASA Astrophysics Data System (ADS)

    Vilana, J.; Gómez, E.; Vallés, E.

    2016-01-01

    Oxidized species of CoNi have been obtained by means of electrodeposition of CoNi films and posterior electro-oxidation, to obtain electrodes able to be catalysts of oxidative reactions in alkaline medium. The products of electro-oxidation formed, which depend on the composition and the crystal phase of CoNi deposits, have been identified; for this, Co-fcc, Co-hcp, Co7Ni3-fcc, Co7Ni3-hcp, Co5Ni5-fcc and Ni-fcc films have been electrodeposited and oxidized. The influence of the crystalline phase of the films in the nature of the superficial oxides formed has been demonstrated: the electrodes prepared from CoNi-fcc films contained β-CoxNi(1⿿x)(OH)2, while those prepared from Co7Ni3-hcp films contained Co2NiO4 and β-CoxNi(1⿿x)(OH)2. The catalytic behaviour of the electro-oxidized electrodes for urea electro-oxidation was evaluated. Separate tests were performed to differentiate the influence of the composition and the crystalline structure of the initial films and, therefore, of the different oxidized species formed. The electrodes prepared by electro-oxidation of the Co7Ni3-hcp films show better electro-catalytic performance for urea's oxidation than those obtained by oxidation of the Co7Ni3-fcc, because they induce higher intensity, lower onset potential and lesser simultaneous oxygen evolution, becoming a good anode for urea electro-oxidation in urea electrolysis for hydrogen production or waste water treatment.

  12. Electrocatalytic determination of sumatriptan on the surface of carbon-paste electrode modified with a composite of cobalt/Schiff-base complex and carbon nanotube.

    PubMed

    Amiri, Mandana; Pakdel, Zohreh; Bezaatpour, Abolfazl; Shahrokhian, Saeed

    2011-06-01

    The electrochemical oxidation of sumatriptan on the surface of carbon paste electrode modified with multi-walled carbon nanotube and cobalt methyl-salophen complex is studied by using cyclic voltammetry and polarization studies. The results indicate that the drug is irreversibly oxidized in a one electron oxidation mechanism. It was found that the peak potential shifted negatively with increasing pH, confirms that H(+) participate in the oxidation process. The electrode is shown to be very effective for the detection of sumatriptan in the presence of other biological reductant compounds. The prepared modified electrode exhibits a very good resolution between the voltammetric peaks of sumatriptan, ascorbic acid and uric acid, which makes it suitable for the simultaneous detection of sumatriptan in the presence of these compounds in clinical and pharmaceutical preparations. It can be concluded that multi-walled carbon nanotube and Shiff base complex have synergic effect on electroacatalytic oxidation of sumatriptan. A linear range of 1-1000μM and detection limit of 0.3μM was obtained for sumatriptan from DPV measurements using this electrode in 0.1M acetate buffered solution of pH 5.0. The electrode has been applied successfully for the determination of sumatriptan in synthetic serum and commercial tablets.

  13. Dye-sensitized solar cell characteristics of nanocomposite zinc ferrite working electrode: effect of composite precursors and titania as a blocking layer on photovoltaic performance.

    PubMed

    Habibi, Mohammad Hossein; Habibi, Amir Hossein; Zendehdel, Mahmoud; Habibi, Mehdi

    2013-06-01

    This research investigates the performance of a zinc ferrite (ZF) as working electrodes in a dye-sensitized solar cell (DSSC). This ZF working electrode was prepared by sol-gel and thermal decomposition of four different precursors including: zinc acetate dihydrate (Zn(CH3COO)2·2H2O), ferric nitrate nonahydrate (Fe(NO3)3·9H2O), iron(III) acetate; Fe(C2H3O2)3, and zinc nitrate hexahydrate, Zn(NO3)2·6H2O. The effects of annealing temperature and precursors on the structural, morphological, and optical properties were investigated. The field emission scanning electron microscope images (FESEM) and scanning electron microscopy (SEM) show that ZFe films are polycrystalline in nature and homogeneous with densely packed grains. Nanoporous zinc ferrite coatings were prepared by doctor blade technique on the fluorine-doped tin oxide (FTO) and used as working electrodes in DSSC. In all DSSCs, platinized FTO and [Co(bpy)3](2+/3+) in 3-methoxy proponitrile were used as counter electrode and redox mediator system respectively. Comparing the fill factors of four different zinc ferrite nanocomposites, the highest fill factor was for ZnFe2O4-TBL sample. Cell fabricated with ZnFeA working electrode shows relatively higher Jsc.

  14. Construction of a carbon ionic liquid paste electrode based on multi-walled carbon nanotubes-synthesized Schiff base composite for trace electrochemical detection of cadmium.

    PubMed

    Afkhami, Abbas; Khoshsafar, Hosein; Bagheri, Hasan; Madrakian, Tayyebeh

    2014-02-01

    A simple, highly sensitive and selective carbon nanocomposite electrode has been developed for the electrochemical trace determination of cadmium. This sensor was designed by incorporation of multi-walled carbon nanotubes (MWCNTs) and a new synthesized Schiff base into the carbon paste ionic liquid electrode (CPE(IL)) which provides remarkably improved sensitivity and selectivity for the electrochemical stripping assay of Cd(II). The detection limit of the method was found to be 0.08 μg L(-1) (S/N=3) that is lower than the maximum contaminant level of Cd(II) allowed by the Environmental Protection Agency (EPA) in standard drinking waters. The proposed electrode exhibits good applicability for monitoring Cd(II) in various real samples.

  15. Electrochemiluminescence sensor for melamine based on a Ru(bpy)₃²⁺-doped silica nanoparticles/carboxylic acid functionalized multi-walled carbon nanotubes/Nafion composite film modified electrode.

    PubMed

    Chen, Xiaomei; Lian, Sai; Ma, Ying; Peng, Aihong; Tian, Xiaotian; Huang, Zhiyong; Chen, Xi

    2016-01-01

    In this work, a sensitive electrochemiluminescence (ECL) sensor for the determination of melamine (MEL) was developed based on a Ru(bpy)3(2+)-doped silica nanoparticles (RUDS)/carboxylic acid functionalized multi-walled carbon nanotubes (CMWCNTs)/Nafion composite film modified electrode. The homogeneous spherical RUDS were synthesized by a reverse microemulsion method. As Ru(bpy)3(2+) were encapsulated in the RUDS, Ru(bpy)3(2+) dropping from the modified electrode can be greatly prevented, which is helpful for obtaining a stable ECL signal. Moreover, to improve the conductivity of the film and promote the electron transfer rate on electrode surface, CMWCNTs with excellent electrical conductivity and large surface area were applied in the construction of the sensing film. As CMWCNTs acted as electron bridges making more Ru(bpy)3(2+) participate in the reaction, the ECL intensity was greatly enhanced. Under the optimum conditions, the relative ECL signal (△IECL) was proportional to the logarithmic MEL concentration ranging from 5×10(-13) to 1×10(-7) mol L(-1) with a detection limit of 1×10(-13) mol L(-1). To verify the reliability, the thus-fabricated ECL sensor was applied to determine the concentration of MEL in milk. Based on these investigations, the proposed ECL sensor exhibited good feasibility and high sensitivity for the determination of MEL, promising the applicability of this sensor in practical analysis.

  16. Electrocatalyst compositions

    DOEpatents

    Mallouk, Thomas E.; Chan, Benny C.; Reddington, Erik; Sapienza, Anthony; Chen, Guoying; Smotkin, Eugene; Gurau, Bogdan; Viswanathan, Rameshkrishnan; Liu, Renxuan

    2001-09-04

    Compositions for use as catalysts in electrochemical reactions are described. The compositions are alloys prepared from two or more elemental metals selected from platinum, molybdenum, osmium, ruthenium, rhodium, and iridium. Also described are electrode compositions including such alloys and electrochemical reaction devices including such catalysts.

  17. Electrophoretic deposition of transparent MoS2-graphene nanosheet composite films as counter electrodes in dye-sensitized solar cells.

    PubMed

    Lin, Jeng-Yu; Chan, Chien-Yi; Chou, Shu-Wei

    2013-02-18

    A transparent MoS(2)-graphene nanosheet (GNS) nanocomposite counter electrode (CE) was incorporated into a Pt-free dye-sensitized solar cell (DSC). The DSC assembled with the transparent MoS(2)-GNS CE therefore exhibited an impressive photovoltaic conversion efficiency of 5.81%, up to 93% of that obtained using the conventional Pt CE (6.24%).

  18. Cellulose-coupled graphene/polypyrrole composite electrodes containing conducting networks built by carbon fibers as wearable supercapacitors with excellent foldability and tailorability

    NASA Astrophysics Data System (ADS)

    Lyu, Shaoyi; Chang, Huanjun; Fu, Feng; Hu, La; Huang, Jingda; Wang, Siqun

    2016-09-01

    A paper-based wearable supercapacitor with excellent foldability and tailorability is fabricated from a chopped carbon fiber (CCF)-reinforced cellulose paper electrode material by coating with reduced graphene oxide (RGO) and polypyrrole (PPy) via in situ polymerization. The CCFs not only form an interpenetrating conducting network that acts as highly conductive electron transfer highways for the RGO/PPy layer in the paper electrode, but also endow the resulting electrode with an excellent areal capacitance of 363 mF cm-2 and a volumetric energy density of 0.28 mW h cm-3. Further, the CCFs give the electrode remarkable mechanical robustness, guaranteeing foldability and tailorability, with only slight loss of capacitance after repeated folding 600 times. Even after being subjected to severe cut-in fracture, the capacitance retention is up to 84%, indicating outstanding damage tolerance. The present study reveals a promising candidate for flexible wearable energy storage devices that are required to function in harsh environments.

  19. Carbon aerogel electrodes for direct energy conversion

    DOEpatents

    Mayer, S.T.; Kaschmitter, J.L.; Pekala, R.W.

    1997-02-11

    A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes is described, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome. 1 fig.

  20. Carbon aerogel electrodes for direct energy conversion

    DOEpatents

    Mayer, Steven T.; Kaschmitter, James L.; Pekala, Richard W.

    1997-01-01

    A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome.

  1. Positive electrode for a lithium battery

    DOEpatents

    Park, Sang-Ho; Amine, Khalil

    2015-04-07

    A method for producing a lithium alkali transition metal oxide for use as a positive electrode material for lithium secondary batteries by a precipitation method. The positive electrode material is a lithium alkali transition metal composite oxide and is prepared by mixing a solid state mixed with alkali and transition metal carbonate and a lithium source. The mixture is thermally treated to obtain a small amount of alkali metal residual in the lithium transition metal composite oxide cathode material.

  2. Electrode structures and surfaces for Li batteries

    DOEpatents

    Thackeray, Michael M.; Kang, Sun-Ho; Balasubramanian, Mahalingam; Croy, Jason

    2017-03-14

    This invention relates to methods of preparing positive electrode materials for electrochemical cells and batteries. It relates, in particular, to a method for fabricating lithium-metal-oxide electrode materials for lithium cells and batteries. The method comprises contacting a hydrogen-lithium-manganese-oxide material with one or more metal ions, preferably in an acidic solution, to insert the one or more metal ions into the hydrogen-lithium-manganese-oxide material; heat-treating the resulting product to form a powdered metal oxide composition; and forming an electrode from the powdered metal oxide composition.

  3. Ceramic component for MHD electrode

    DOEpatents

    Marchant, David D.; Bates, Junior L.

    1981-01-01

    A ceramic component which exhibits electrical conductivity down to near room temperatures has the formula: Hf.sub.x In.sub.y A.sub.z O.sub.2 where x=0.1 to 0.4, y=0.3 to 0.6, z=0.1 to 0.4 and A is a lanthanide rare earth or yttrium. The component is suitable for use in the fabrication of MHD electrodes or as the current leadout portion of a composite electrode with other ceramic components.

  4. Ceramic components for MHD electrode

    DOEpatents

    Marchant, D.D.

    A ceramic component which exhibits electrical conductivity down to near room temperatures has the formula: Hf/sub x/In/sub y/A/sub z/O/sub 2/ where x = 0.1 to 0.4, y = 0.3 to 0.6, z = 0.1 to 0.4 and A is a lanthanide rare earth or yttrium. The component is suitable for use in the fabrication of MHD electrodes or as the current leadout portion of a composite electrode with other ceramic components.

  5. Bulk-Type All-Solid-State Lithium-Ion Batteries: Remarkable Performances of a Carbon Nanofiber-Supported MgH2 Composite Electrode.

    PubMed

    Zeng, Liang; Ichikawa, Takayuki; Kawahito, Koji; Miyaoka, Hiroki; Kojima, Yoshitsugu

    2017-01-25

    Magnesium hydride, MgH2, a recently developed compound for lithium-ion batteries, is considered to be a promising conversion-type negative electrode material due to its high theoretical lithium storage capacity of over 2000 mA h g(-1), suitable working potential, and relatively small volume expansion. Nevertheless, it suffers from unsatisfactory cyclability, poor reversibility, and slow kinetics in conventional nonaqueous electrolyte systems, which greatly limit the practical application of MgH2. In this work, a vapor-grown carbon nanofiber was used to enhance the electrical conductivity of MgH2 using LiBH4 as the solid-state electrolyte. It shows that a reversible capacity of over 1200 mA h g(-1) with an average voltage of 0.5 V (vs Li/Li(+)) can be obtained after 50 cycles at a current density of 1000 mA g(-1). In addition, the capacity of MgH2 retains over 1100 mA h g(-1) at a high current density of 8000 mA g(-1), which indicates the possibility of using MgH2 as a negative electrode material for high power and high capacity lithium-ion batteries in future practical applications. Moreover, the widely studied sulfide-based solid electrolyte was also used to assemble battery cells with MgH2 electrode in the same system, and the electrochemical performance was as good as that using LiBH4 electrolyte.

  6. A novel solid-state electrochemiluminescence sensor for melamine with Ru(bpy)3(2+)/mesoporous silica nanospheres/Nafion composite modified electrode.

    PubMed

    Cao, Hongmei; Hu, Xiaoqing; Hu, Chenyi; Zhang, Yang; Jia, Nengqin

    2013-03-15

    A novel melamine electrochemiluminescence (ECL) sensor was developed based on mesoporous SiO(2) nanospheres/Ru(bpy)(3)(2+)/Nafion modified electrodes. The homogeneous mesoporous silica nanospheres, synthesized using modified Stöber sol-gel process, were characterized by Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM) and Brunauer-Emmett-Teller (BET). The ECL and electrochemistry of the modified electrodes were investigated with tri-n-propylamine (TPA) as the coreactant. Furthermore, the mesporous SiO(2) nanospheres/Ru(bpy)(3)(2+)-based modified electrodes were used for ECL determination of melamine. The analytical performances of this ECL sensor for melamine based on its enhancement ECL emission of Ru(bpy)(3)(2+) were investigated. The results indicated that the sensor exhibited excellent performance during melamine determination with a wide linear range (7.81×10(-9)-5×10(-6) M), low detection limit (2.6×10(-9) M). The high sensitivity and stability mainly resulted from the high surface area and special structure of the mesoporous silica nanospheres. The proposed ECL approach was used to analyze the melamine content in powdered milk with satisfactory results.

  7. Perovskite electrodes and method of making the same

    DOEpatents

    Seabaugh, Matthew M.; Swartz, Scott L.

    2009-09-22

    The invention relates to perovskite oxide electrode materials in which one or more of the elements Mg, Ni, Cu, and Zn are present as minority components that enhance electrochemical performance, as well as electrode products with these compositions and methods of making the electrode materials. Such electrodes are useful in electrochemical system applications such as solid oxide fuel cells, ceramic oxygen generation systems, gas sensors, ceramic membrane reactors, and ceramic electrochemical gas separation systems.

  8. Perovskite electrodes and method of making the same

    DOEpatents

    Seabaugh, Matthew M.; Swartz, Scott L.

    2005-09-20

    The invention relates to perovskite oxide electrode materials in which one or more of the elements Mg, Ni, Cu, and Zn are present as minority components that enhance electrochemical performance, as well as electrode products with these compositions and methods of making the electrode materials. Such electrodes are useful in electrochemical system applications such as solid oxide fuel cells, ceramic oxygen generation systems, gas sensors, ceramic membrane reactors, and ceramic electrochemical gas separation systems.

  9. Extrusion of electrode material by liquid injection into extruder barrel

    DOEpatents

    Keller, David Gerard; Giovannoni, Richard Thomas; MacFadden, Kenneth Orville

    1998-01-01

    An electrode sheet product is formed using an extruder having a feed throat and a downstream section by separately mixing an active electrode material and a solid polymer electrolyte composition that contains lithium salt. The active electrode material is fed into the feed throat of the extruder, while a portion of at least one fluid component of the solid polymer electrolyte composition is introduced to the downstream section. The active electrode material and the solid polymer electrolyte composition are compounded in a downstream end of the extruder. The extruded sheets, adhered to current collectors, can be formed into battery cells.

  10. Extrusion of electrode material by liquid injection into extruder barrel

    DOEpatents

    Keller, D.G.; Giovannoni, R.T.; MacFadden, K.O.

    1998-03-10

    An electrode sheet product is formed using an extruder having a feed throat and a downstream section by separately mixing an active electrode material and a solid polymer electrolyte composition that contains lithium salt. The active electrode material is fed into the feed throat of the extruder, while a portion of at least one fluid component of the solid polymer electrolyte composition is introduced to the downstream section. The active electrode material and the solid polymer electrolyte composition are compounded in a downstream end of the extruder. The extruded sheets, adhered to current collectors, can be formed into battery cells. 1 fig.

  11. Ion-Selective Electrodes.

    ERIC Educational Resources Information Center

    Arnold, Mark A.; Meyerhoff, Mark E.

    1984-01-01

    Literature on ion-selective electrodes (ISEs) is reviewed in seven sections: books, conferences, reviews; potentiometric membrane electrodes; glass and solid-state membrane electrodes; liquid and polymer membrane ISEs; coated wire electrodes, ion-selective field effect transistors, and microelectrodes; gas sensors and selective bioelectrode…

  12. Peanut-like MnO@C core-shell composites as anode electrodes for high-performance lithium ion batteries.

    PubMed

    Wang, Shengbin; Ren, Yanbiao; Liu, Guanrao; Xing, Yalan; Zhang, Shichao

    2014-04-07

    Peanut-like MnO@C core-shell composites with an internal carbon network (P-MnO@C) were prepared via an in situ synchronous graphitization and reduction process. These P-MnO@C composites exhibit high specific capacity and rate capability, good stability and excellent long-term cycling life for application in lithium ion batteries.

  13. HSPES membrane electrode assembly

    NASA Technical Reports Server (NTRS)

    Kindler, Andrew (Inventor); Yen, Shiao-Ping (Inventor)

    2000-01-01

    An improved fuel cell electrode, as well as fuel cells and membrane electrode assemblies that include such an electrode, in which the electrode includes a backing layer having a sintered layer thereon, and a non-sintered free-catalyst layer. The invention also features a method of forming the electrode by sintering a backing material with a catalyst material and then applying a free-catalyst layer.

  14. Study of synergistic effect among photo-, electro-, and sonoprocesses in photocatalyst degradation of phenol on tungsten-loaded titania nanotubes composite electrode

    NASA Astrophysics Data System (ADS)

    Momeni, Mohamad Mohsen

    2015-06-01

    The degradation of 4-nitrophenol (4-NP) in aqueous solution with different processes was investigated. Tungsten-loaded titania nanotubes (WT-NTs) were used as electrode in photocatalytic (PC), sonophotocatalytic (SPC), photoelectrocatalytic (PEC), and sonophotoelectrocatalytic (SPEC) processes. WT-NTs electrode was fabricated by in situ anodization of titanium in a single-step process using sodium tungstate as the tungsten source. The morphology and structure were characterized by FE-SEM, XRD, and EDX. Experimental results showed that the hybrid processes could efficiently enhance the degradation efficiency of 4-NP and followed pseudo-first-order kinetics. At the optimized experimental conditions, the rate constants of degradation of 4-NP were 0.0594 min-1 for SPEC process, 0.0293 min-1 for PEC process, 0.0211 min-1 for SPC process, and 0.0116 min-1 for PC process. The rate constants indicated that there existed synergistic effect in the ultrasonic, electro-assisted, and photocatalytic processes.

  15. Electrochemical determination of L-phenylalanine at polyaniline modified carbon electrode based on β-cyclodextrin incorporated carbon nanotube composite material and imprinted sol-gel film.

    PubMed

    Hu, Yu-fang; Zhang, Zhao-hui; Zhang, Hua-bin; Luo, Li-juan; Yao, Shou-zhuo

    2011-04-15

    A sensitive and selective electrochemical sensor based on a polyaniline modified carbon electrode for the determination of L-phenylalanine has been proposed by utilizing β-cyclodextrin (β-CD) incorporated multi-walled carbon nanotube (MWNT) and imprinted sol-gel film. The electrochemical behavior of the sensor towards L-phenylalanine was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometric i-t curve. The surface morphologies of layer-by-layer assembly electrodes were displayed by scanning electron microscope (SEM). The response mechanism of the imprinted sensor for L-phenylalanine was based on the inclusion interaction of β-CD and molecular recognition capacity of the imprinted film for L-phenylalanine. A linear calibration plot was obtained covering the concentration range from 5.0 × 10(-7) to 1.0 × 10(-4) mol L(-1) with a detection limit of 1.0 × 10(-9) mol L(-1). With excellent sensitivity, selectivity, stability, reproducibility and recovery, the electrochemical imprinted sensor was used to detect L-phenylalanine in blood plasma samples successfully.

  16. Visualization of Charge Distribution in a Lithium Battery Electrode

    SciTech Connect

    Liu, Jun; Kunz, Martin; Chen, Kai; Tamura, Nobumichi; Richardson, Thomas J.

    2010-07-02

    We describe a method for direct determination and visualization of the distribution of charge in a composite electrode. Using synchrotron X-ray microdiffraction, state-of-charge profiles in-plane and normal to the current collector were measured. In electrodes charged at high rate, the signatures of nonuniform current distribution were evident. The portion of a prismatic cell electrode closest to the current collector tab had the highest state of charge due to electronic resistance in the composite electrode and supporting foil. In a coin cell electrode, the active material at the electrode surface was more fully charged than that close to the current collector because the limiting factor in this case is ion conduction in the electrolyte contained within the porous electrode.

  17. Controlled porosity in electrodes

    DOEpatents

    Chiang, Yet-Ming; Bae, Chang-Jun; Halloran, John William; Fu, Qiang; Tomsia, Antoni P.; Erdonmez, Can K.

    2015-06-23

    Porous electrodes in which the porosity has a low tortuosity are generally provided. In some embodiments, the porous electrodes can be designed to be filled with electrolyte and used in batteries, and can include low tortuosity in the primary direction of ion transport during charge and discharge of the battery. In some embodiments, the electrodes can have a high volume fraction of electrode active material (i.e., low porosity). The attributes outlined above can allow the electrodes to be fabricated with a higher energy density, higher capacity per unit area of electrode (mAh/cm.sup.2), and greater thickness than comparable electrodes while still providing high utilization of the active material in the battery during use. Accordingly, the electrodes can be used to produce batteries with high energy densities, high power, or both compared to batteries using electrodes of conventional design with relatively highly tortuous pores.

  18. Micromachined electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.

    2007-12-11

    An electrode array is disclosed which has applications for neural stimulation and sensing. The electrode array, in certain embodiments, can include a plurality of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. In other embodiments of the electrode array, the electrodes can be fixed to the substrate. The electrode array can be formed from a combination of bulk and surface micromachining, and can include electrode tips having an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis.

  19. Flexible retinal electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.; Christenson, Todd R.

    2006-10-24

    An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

  20. High frequency reference electrode

    DOEpatents

    Kronberg, James W.

    1994-01-01

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

  1. High frequency reference electrode

    DOEpatents

    Kronberg, J.W.

    1994-05-31

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

  2. High Rate Capability Core-Shell SnO2/Multiwall Carbon Nanotube Nano Composite Electrodes for Li-Ion Batteries.

    PubMed

    Akbulut, Hatem; Guler, Mehmet Oguz

    2015-09-01

    In this study, core-shell SnO2/MWCNT nanocomposites were produced as a high rate anode material for Li-ion batteries via two steps. Firstly, MWCNT based buckypapers were produced via vacuum filtration techniques. Then, a uniform layer of tin oxide nanocrystals which consist of highly homogenous SnO2 having average mean grain sizes of 7-14 nm was deposited onto the surfaces of buckypapers. The as-prepared nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), galvanostatic charging and discharging and electrochemical impedance spectroscopy (EIS) tests. As anode materials for Li-ion batteries, the nanocomposites showed excellent cyclic retention, with the high specific capacity of 314 mAh g(-1) up to 100 cycles. The special hybrid core-shell structure of the as produced nanocomposites are served as electron conductors and volume buffers in the anode electrodes.

  3. Coated magnetic particles in electrochemical systems: Synthesis, modified electrodes, alkaline batteries, and paste electrodes

    NASA Astrophysics Data System (ADS)

    Unlu, Murat

    Magnetic field effects on electrochemical reactions have been studied and shown to influence kinetics and dynamics. Recently, our group has introduced a novel method to establish magnetic field effects by incorporating inert, magnetic microparticles onto the electrode structure. This modification improved several electrochemical systems including modified electrodes, alkaline batteries, and fuel cells. This dissertation describes the applicability of magnetic microparticles and the understanding of magnetic field effects in modified electrodes, alkaline batteries, and paste electrodes. Magnetic effects are studied on electrodes that are coated with an ion exchange polymer that embeds chemically inert, commercial, magnetic microparticles. The flux (electrolysis current) of redox probe to the magnetically modified system is compared to a similar non-magnetic electrode. Flux enhancements of 60% are achieved at magnetically modified electrode as compared to non-magnetic controls. In addition to modifying electrode surfaces, the incorporation of magnetic microparticles into the electrode material itself establishes a 20% increase in flux. Possible magnetic field effects are evaluated. Study of samarium cobalt modified electrolytic manganese dioxide, EMD electrodes further establish a magnetic effect on alkaline cathode performance. Magnetic modification improves alkaline battery performance in primary and secondary applications. The reaction mechanism is examined through voltammetric methods. This work also includes coating protocols to produce inert magnetic microparticles with high magnetic content. Magnetite powders are encapsulated in a polymer matrix by dispersion polymerization. Composite particles are examined in proton exchange membrane fuel cells to study carbon monoxide tolerance.

  4. Characterization and basic research investigations at PEFC electrodes and MEA

    SciTech Connect

    Schulze, M.; Wagner, N.; Steinhilber, G.

    1996-12-31

    For the study of electrochemical and transport mechanisms in polymere electrolyte fuel cells (PEFC) electrodes and for a further development of PEFC electrodes it is important to characterize these electrodes. The characterization of the electrodes was performed by electrochemical analytical as well as physical methods on both single electrodes and electrode-membrane assemblies (NEA). In addition to voltage-current characteristics the electrodes were electrochemically measured by cyclic voltammetry, electrochemical impedance spectroscopy and chronopotentiometry. To determine the pore systems nitrogen adsorption and mercury porosimetry were used. Chemical composition and microstructure of the electrodes were studied by surface science methods like scanning electron microscopy or X-ray induced photoelectron spectroscopy. The results of characterization are the base for theoretical simulation of fuel cells and fuel cell stacks.

  5. High performance cermet electrodes

    DOEpatents

    Isenberg, Arnold O.; Zymboly, Gregory E.

    1986-01-01

    Disclosed is a method of increasing the operating cell voltage of a solid oxide electrochemical cell having metal electrode particles in contact with an oxygen-transporting ceramic electrolyte. The metal electrode is heated with the cell, and oxygen is passed through the oxygen-transporting ceramic electrolyte to the surface of the metal electrode particles so that the metal electrode particles are oxidized to form a metal oxide layer between the metal electrode particles and the electrolyte. The metal oxide layer is then reduced to form porous metal between the metal electrode particles and the ceramic electrolyte.

  6. Skin contact electrodes for medical applications.

    PubMed

    Eggins, B R

    1993-04-01

    Skin contact electrodes require electrolyte gels between the skin and the electrode in order to ensure good electrical contact. The effect of different types of electrolyte gel on skin impedance was studied. The main types of gels used were wet gels, karaya-gum based hydrogels and synthetic copolymer-based hydrogels [2-acrylamide-2-methylpropanesulfonic acid-N,N'-methylenebis(acrylamide) copolymers]. The effect of variation in gel composition on the impedance of the skin was investigated.

  7. From Christmas Ornament to Glass Electrode

    NASA Astrophysics Data System (ADS)

    da Rocha, Rogério T.; Gutz, Ivano G. R.; Do Lago, Claudimir L.

    1995-12-01

    In potentiometric techniques, pH measurements require a costly and fragile accessory: the glass electrode. A glass electrode is difficult to make because the wall of the sensing glass bulb must be very thin, and glass of special composition is required. Although the glass bulb may be made by a skilled glazier, we choose a more impressive and simple way. The glass bulb can be made from a Christmas-tree ornamental ball.

  8. Electrode and method of interconnection sintering on an electrode of an electrochemical cell

    DOEpatents

    Ruka, R.J.; Kuo, L.J.H.

    1994-01-11

    An electrode structure is made by applying a base layer of doped LaCrO[sub 3] particles on a portion of an electrode and then coating the particles with a top layer composition such as CaO+Al[sub 2]O[sub 3], SrO+Al[sub 2]O[sub 3], or BaO+Al[sub 2]O[sub 3], and then heating the composition for a time effective to melt the composition and allow it to fill any open porosity in the base layer of doped LaCrO[sub 3] to form an interconnection, after which solid oxide electrolyte can be applied to the remaining portion of the electrode and the electrolyte can be covered with a cermet exterior electrode. 2 figures.

  9. Electrode and method of interconnection sintering on an electrode of an electrochemical cell

    DOEpatents

    Ruka, Roswell J.; Kuo, Lewis J. H.

    1994-01-01

    An electrode structure (10) is made by applying a base layer of doped LaCrO.sub.3 particles on a portion of an electrode (16) and then coating the particles with a top layer composition such as CaO+Al.sub.2 O.sub.3, SrO+Al.sub.2 O.sub.3, or BaO+Al.sub.2 O.sub.3, and then heating the composition for a time effective to melt the composition and allow it to fill any open porosity in the base layer of doped LaCrO.sub.3 to form an interconnection (26), after which solid oxide electrolyte (18) can be applied to the remaining portion of the electrode (16) and the electrolyte (18) can be covered with a cermet exterior electrode (20).

  10. FUEL CELL ELECTRODE MATERIALS

    DTIC Science & Technology

    FUEL CELL ELECTRODE MATERIALS. RAW MATERIAL SELECTION INFLUENCES POLARIZATION BUT IS NOT A SINGLE CONTROLLING FACTOR. AVAILABLE...DATA INDICATES THAT AN INTERRELATIONSHIP OF POROSITY, AVERAGE PORE VOLUME, AND PERMEABILITY CONTRIBUTES TO ELECTRODE FUEL CELL BEHAVIOR.

  11. Improved biomedical electrode

    NASA Technical Reports Server (NTRS)

    Frost, J. D., Jr.

    1972-01-01

    Newly designed electrode is prefilled, disposable, electrolyte-saturated spong. New design permits longe periods of storage without deterioration, and readiness in matter of seconds. Electrodes supply signals for electroencephalogram, electro-oculogram, and electrocardiogram.

  12. Corneal-shaping electrode

    DOEpatents

    Doss, James D.; Hutson, Richard L.

    1982-01-01

    The disclosure relates to a circulating saline electrode for changing corneal shape in eyes. The electrode comprises a tubular nonconductive electrode housing having an annular expanded base which has a surface substantially matched to a subject corneal surface. A tubular conductive electrode connected to a radiofrequency generating source is disposed within the electrode housing and longitudinally aligned therewith. The electrode has a generally hemispherical head having at least one orifice. Saline solution is circulated through the apparatus and over the cornea to cool the corneal surface while radiofrequency electric current emitted from the electrode flows therefrom through the cornea to a second electrode, on the rear of the head. This current heats the deep corneal stroma and thereby effects corneal reshaping as a biological response to the heat.

  13. Biomass transition metal hydrogen-evolution electrocatalysts and electrodes

    DOEpatents

    Chen, Wei-Fu; Iyer, Shweta; Iyer, Shilpa; Sasaki, Kotaro; Muckerman, James T.; Fujita, Etsuko

    2017-02-28

    A catalytic composition from earth-abundant transition metal salts and biomass is disclosed. A calcined catalytic composition formed from soybean powder and ammonium molybdate is specifically exemplified herein. Methods for making the catalytic composition are disclosed as are electrodes for hydrogen evolution reactions comprising the catalytic composition.

  14. The CMG Nickel Electrode

    NASA Technical Reports Server (NTRS)

    Depaul, R. A.; Gutridge, I.

    1981-01-01

    The development and design of the Controlled Microgeometry electrode are described. Advantages of the electrode over others in existance include a higher number of ampere hours per kilogram and the ability to make them over a wide range of thicknesses. The parameters that control the performance of the electrode can be individually controlled over a wide range. Therefore, the electrode may be designed to give the optimum performance for a given duty cycle.

  15. Low resistance fuel electrodes

    DOEpatents

    Maskalick, Nichols J.; Folser, George R.

    1989-01-01

    An electrode 6 bonded to a solid, ion conducting electrolyte 5 is made, where the electrode 6 comprises a ceramic metal oxide 18, metal particles 17, and heat stable metal fibers 19, where the metal fibers provide a matrix structure for the electrode. The electrolyte 5 can be bonded to an air electrode cathode 4, to provide an electrochemical cell 2, preferably of tubular design.

  16. Compartmented electrode structure

    DOEpatents

    Vissers, Donald R.; Shimotake, Hiroshi; Gay, Eddie C.; Martino, Fredric J.

    1977-06-14

    Electrodes for secondary electrochemical cells are provided with compartments for containing particles of the electrode reactant. The compartments are defined by partitions that are generally impenetrable to the particles of reactant and, in some instances, to the liquid electrolyte used in the cell. During cycling of the cell, reactant material initially loaded into a particular compartment is prevented from migrating and concentrating within the lower portion of the electrode or those portions of the electrode that exhibit reduced electrical resistance.

  17. Ag y :TiN x thin films for dry biopotential electrodes: the effect of composition and structural changes on the electrical and mechanical behaviours

    NASA Astrophysics Data System (ADS)

    Pedrosa, P.; Machado, D.; Borges, J.; Rodrigues, M. S.; Alves, E.; Barradas, N. P.; Martin, N.; Evaristo, M.; Cavaleiro, A.; Fonseca, C.; Vaz, F.

    2015-04-01

    In the present work, Ag y :TiN x thin films, obtained by reactive DC magnetron sputtering, with decreasing [N]/[Ti] atomic ratios (from 1 to 0.1) and a fixed amount of Ag pellets placed in the erosion zone of a pure Ti target, were studied envisaging their application as biopotential electrodes. The strongly under-stoichiometric samples, [N]/[Ti] = 0.1 and 10 at.% Ag; [N]/[Ti] = 0.2 and 8 at.% Ag, were found to be composed of a N-doped hcp-Ti structure, with possible formation of TiAg or Ti2Ag intermetallics. These samples exhibit high electrical resistivity values and low hardness and reduced modulus. In the set of samples indexed to a transition zone, [N]/[Ti] = 0.3 and 15 at.% Ag; [N]/[Ti] = 0.7 and 32 at.% Ag, a hcp-Ti to fcc-TiN phase transformation took place, giving rise to a disaggregated N-deficient TiN matrix. It correlates with the high resistivity values as well as the higher hardness and reduced modulus values that were obtained. The last identified zone comprised the stoichiometric Ag:TiN x sample—[N]/[Ti] = 1 and 20 at.% Ag. Extensive metallic Ag segregation was detected, contributing to a significant decrease of the resistivity and hardness values.

  18. Determination of Pb(II) by sequential injection/stripping analysis at all-plastic electrochemical fluidic cells with integrated composite electrodes.

    PubMed

    Kokkinos, Christos; Economou, Anastasios; Goddard, Nicholas G; Fielden, Peter R; Baldock, Sara J

    2016-06-01

    This work reports the development of a sequential injection/stripping analysis method for the determination of trace Pb(II) at injection-moulded electrochemical fluidic cells. Conducting carbon fibre-loaded polystyrene electrodes were integrated within the plastic cells. The flow-through cells were incorporated into a home-made sequential injection analysis (SIA) manifold. Different experimental parameters for the detection of Pb(II) were investigated including the type and concentration of the supporting electrolyte, the conditions of the stripping step, the volume of the sample, the flow rate and the accumulation potential. The LOD for Pb(II) was 0.5μgL(-1), the within-cell % relative standard deviation (n=8) was 3.1% and the between-cell % relative standard deviation (n=5) was 8.9% for 25μgL(-1) Pb(II). The cells were applied to the determination of Pb(II) in tapwater and a phosphate fertilizer sample.

  19. CTAB functionalized graphene oxide/multiwalled carbon nanotube composite modified electrode for the simultaneous determination of ascorbic acid, dopamine, uric acid and nitrite.

    PubMed

    Yang, Yu Jun; Li, Weikun

    2014-06-15

    We have developed hexadecyl trimethyl ammonium bromide (CTAB) functionalized graphene oxide (GO)/multiwalled carbon nanotubes (MWNTs) modified glassy carbon electrode (CTAB-GO/MWNT) as a novel system for the simultaneous determination of dopamine (DA), ascorbic acid (AA), uric acid (UA) and nitrite (NO2(-)). The combination of graphene oxide and MWNTs endow the biosensor with large surface area, good biological compatibility, electricity and stability, high selectivity and sensitivity. In the fourfold co-existence system, the linear calibration plots for AA, DA, UA and NO2(-) were obtained over the range of 5.0-300 μM, 5.0-500 μM, 3.0-60 μM and 5.0-800 μM with detection limits of 1.0 μM, 1.5 μM, 1.0 μM and 1.5 μM, respectively. In addition, the modified biosensor was applied to the determination of AA, DA, UA and NO2(-) in urine samples by using standard adding method with satisfactory results.

  20. Insulated ECG electrodes

    NASA Technical Reports Server (NTRS)

    Portnoy, W. M.; David, R. M.

    1973-01-01

    Insulated, capacitively coupled electrode does not require electrolyte paste for attachment. Other features of electrode include wide range of nontoxic material that may be employed for dielectric because of sputtering technique used. Also, electrode size is reduced because there is no need for external compensating networks with FET operational amplifier.

  1. Fuel cell electrodes

    DOEpatents

    Strmcnik, Dusan; Cuesta, Angel; Stamenkovic, Vojislav; Markovic, Nenad

    2015-06-23

    A process includes patterning a surface of a platinum group metal-based electrode by contacting the electrode with an adsorbate to form a patterned platinum group metal-based electrode including platinum group metal sites blocked with adsorbate molecules and platinum group metal sites which are not blocked.

  2. Aerospace electrode line

    NASA Astrophysics Data System (ADS)

    Miller, L.

    1980-04-01

    A facility which produces electrodes for spacecraft power supplies is described. The electrode assembly procedures are discussed. A number of design features in the production process are reported including a batch operation mode and an independent equipment module design approach for transfering the electrode materials from process tank to process tank.

  3. Electrically conductive diamond electrodes

    DOEpatents

    Swain, Greg; Fischer, Anne ,; Bennett, Jason; Lowe, Michael

    2009-05-19

    An electrically conductive diamond electrode and process for preparation thereof is described. The electrode comprises diamond particles coated with electrically conductive doped diamond preferably by chemical vapor deposition which are held together with a binder. The electrodes are useful for oxidation reduction in gas, such as hydrogen generation by electrolysis.

  4. Microresonator electrode design

    DOEpatents

    Olsson, III, Roy H.; Wojciechowski, Kenneth; Branch, Darren W.

    2016-05-10

    A microresonator with an input electrode and an output electrode patterned thereon is described. The input electrode includes a series of stubs that are configured to isolate acoustic waves, such that the waves are not reflected into the microresonator. Such design results in reduction of spurious modes corresponding to the microresonator.

  5. A Simple Hydrogen Electrode

    ERIC Educational Resources Information Center

    Eggen, Per-Odd

    2009-01-01

    This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements…

  6. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, B.E.; Miller, J.L.; Ault, E.R.

    1994-08-23

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window. 2 figs.

  7. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, Bruce E.; Miller, John L.; Ault, Earl R.

    1994-01-01

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window.

  8. Synthesis of platinum-polyaniline composite, its evaluation as a performance boosting interphase in the electrode assembly of proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Jayasree, R.; Mohanraju, K.; Cindrella, L.

    2013-01-01

    Platinum formed on polyaniline (PANi) is used as the interlayer between porous gas diffusion layer and the catalyst layer with the aim to reduce the thickness of the ordinary gas diffusion layer and provide a performance boosting electrostatic layer. The doping tendency of PANi is utilized to incorporate platinum(IV) ion in its matrix by chemisorption followed by its reduction to metallic platinum. Platinum is deposited on polyaniline by a simple wet chemistry method. PANi is prepared by the chemical oxidative polymerization of aniline by ammonium persulphate while Pt deposition on PANi is achieved by a phase transfer method (water-toluene) to yield Pt nanoparticles on PANi. The composite is characterized by XRD, Scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), IR spectroscopy, cyclic voltammetry (CV), AC impedance studies, density and conductivity measurements. The Pt/PANi composite is assessed in the proton exchange membrane fuel cell (PEMFC) using H2/O2 gases at ambient pressure. The performance of the PEMFC with Pt/PANi composite interphase on cathode side of the gas diffusion layer (GDL) shows improvement at high current densities which is attributed to the increased capacitative current of Pt/PANi layer in the presence of O2 thereby improving the kinetics of subsequent reduction of O2.

  9. Graphene nanocomposites for electrochemical cell electrodes

    DOEpatents

    Zhamu, Aruna; Jang, Bor Z.; Shi, Jinjun

    2015-11-19

    A composite composition for electrochemical cell electrode applications, the composition comprising multiple solid particles, wherein (a) a solid particle is composed of graphene platelets dispersed in or bonded by a first matrix or binder material, wherein the graphene platelets are not obtained from graphitization of the first binder or matrix material; (b) the graphene platelets have a length or width in the range of 10 nm to 10 .mu.m; (c) the multiple solid particles are bonded by a second binder material; and (d) the first or second binder material is selected from a polymer, polymeric carbon, amorphous carbon, metal, glass, ceramic, oxide, organic material, or a combination thereof. For a lithium ion battery anode application, the first binder or matrix material is preferably amorphous carbon or polymeric carbon. Such a composite composition provides a high anode capacity and good cycling response. For a supercapacitor electrode application, the solid particles preferably have meso-scale pores therein to accommodate electrolyte.

  10. Simultaneous determination of 2,4,6-trichlorophenol and pentachlorophenol based on poly(Rhodamine B)/graphene oxide/multiwalled carbon nanotubes composite film modified electrode

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaolin; Zhang, Kexin; Lu, Nan; Yuan, Xing

    2016-01-01

    In the present study, a poly(Rhodamine B)/graphene oxide/multiwalled carbon nanotubes nanocomposite modified glass carbon electrode (PRhB/GO/MWCNTs/GCE) was developed for the simultaneous determination of 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP). The PRhB/GO/MWCNTs film was extensively characterized by emission scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and electrochemical impedance spectroscopy (EIS). The electrochemical behaviors of 2,4,6-TCP and PCP were investigated by cyclic voltammetry, linear sweep voltammetry and differential pulse voltammetry. Due to the synergistic effect, the PRhB/GO/MWCNTs/GCE significantly facilitated the simultaneous electro-oxidation of 2,4,6-TCP and PCP with peak potential difference of 160 mV and enhanced oxidation currents. Under optimum conditions, the oxidation current of 2,4,6-TCP was linear to its concentration in the ranges of 4.0 × 10-9 to 1.0 × 10-7 M and 1.0 × 10-7 to 1.0 × 10-4 M with the detection limit (S/N = 3) of 8.0 × 10-10 M. And the linear concentration ranges for PCP were 2.0 × 10-9 to 1.0 × 10-7 M and 1.0 × 10-7 to 9.0 × 10-5 M with the detection limit of 5.0 × 10-10 M. Moreover, the proposed PRhB/GO/MWCNTs/GCE was successfully applied to the simultaneous determination of 2,4,6-TCP and PCP in practical water samples.

  11. Composites

    NASA Astrophysics Data System (ADS)

    Taylor, John G.

    The Composites market is arguably the most challenging and profitable market for phenolic resins aside from electronics. The variety of products and processes encountered creates the challenges, and the demand for high performance in critical operations brings value. Phenolic composite materials are rendered into a wide range of components to supply a diverse and fragmented commercial base that includes customers in aerospace (Space Shuttle), aircraft (interiors and brakes), mass transit (interiors), defense (blast protection), marine, mine ducting, off-shore (ducts and grating) and infrastructure (architectural) to name a few. For example, phenolic resin is a critical adhesive in the manufacture of honeycomb sandwich panels. Various solvent and water based resins are described along with resin characteristics and the role of metal ions for enhanced thermal stability of the resin used to coat the honeycomb. Featured new developments include pultrusion of phenolic grating, success in RTM/VARTM fabricated parts, new ballistic developments for military vehicles and high char yield carbon-carbon composites along with many others. Additionally, global regional market resin volumes and sales are presented and compared with other thermosetting resin systems.

  12. Igniter electrode life control

    SciTech Connect

    Scott, J.C.

    1985-10-07

    The prevention of electrode material erosion by undercutting in the outer electrode shell of igniter electrodes of jet engine ignition systems is prevented by the application of an electrical insulation coating. The coating is applied to the surface of the outer electrode shell which faces the ceramic insulation around the center electrode where erosion patterns are known to occur. The insulation material is selected from electrical insulation substances such as oxides of aluminum, tungsten, magnesium, beryllium or zirconium by choosing a non-porous electrical-insulating substance with thermal-expansion characteristics approximately equalling those of the outer electrode shell. Since a typical outer electrode shell is composed of 446 stainless steel, an optimum choice for the electrical insulation coating is Al/sub 2/O/sub 3/ deposited with a coating thickness of between 5 and 10 mils.

  13. Fabricating solid carbon porous electrodes from powders

    DOEpatents

    Kaschmitter, J.L.; Tran, T.D.; Feikert, J.H.; Mayer, S.T.

    1997-06-10

    Fabrication is described for conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive deionization, and waste treatment. Electrodes fabricated from low surface area (<50 m{sup 2}/gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon composites with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to high surface area carbons, fuel cell electrodes can be produced. 1 fig.

  14. Fabricating solid carbon porous electrodes from powders

    DOEpatents

    Kaschmitter, James L.; Tran, Tri D.; Feikert, John H.; Mayer, Steven T.

    1997-01-01

    Fabrication of conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive dionization, and waste treatment. Electrodes fabricated from low surface area (<50 m.sup.2 /gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon compositives with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to be high surface area carbons, fuel cell electrodes can be produced.

  15. Soft-template-synthesis of hollow CuO/Co3O4 composites for pseudo-capacitive electrode: A synergetic effect on electrochemical performance

    NASA Astrophysics Data System (ADS)

    Wang, Kuaibing; Lv, Bo; Wu, Hua; Luo, Xuefei; Xu, Jiangyan; Geng, Zhirong

    2016-12-01

    Hollow CuO/Co3O4 hybrids, which inherited from its coordination polymer precursor consisting of sheets layer and nanoparticles layer composites, were synthesized and characterized by SEM, EDX, XRD and XPS. To assess its electrochemical capacitive performances, cyclic voltammetry, galvanostatic charging-discharging measurements and A.C. impedance tests were performed successively. The CuO/Co3O4 hybrids had higher capacitance and lower charge transfer resistance than bare Co3O4 nanostructures, revealing that it provided a protection layer and produced a synergistic effect due to the existence of CuO layer. The distinct synergistic effect could be further confirmed by endurance cycling tests. The capacitance of the CuO/Co3O4 hybrids was 111% retained after 500 cycles at a charging rate of 1.0 A g-1 and remained an intense growth trend after 2000 cycles at scan rate of 200 mV s-1.

  16. Solid electrolyte-electrode system for an electrochemical cell

    DOEpatents

    Tuller, Harry L.; Kramer, Steve A.; Spears, Marlene A.

    1995-01-01

    An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided.

  17. Solid electrolyte-electrode system for an electrochemical cell

    DOEpatents

    Tuller, H.L.; Kramer, S.A.; Spears, M.A.

    1995-04-04

    An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided. 17 figures.

  18. Electrode Engineering of Conversion-based Negative Electrodes for Na-ion Batteries.

    PubMed

    Vogt, Leonie O; Marino, Cyril; Villevieille, Claire

    2015-01-01

    Due to lower costs and higher abundance of sodium, Na-ion battery technology can offer a good alternative to Li-ion batteries. Much research is focusing on developing new cathode and anode materials but the importance of the electrode engineering on the electrochemical performance is often neglected. The electrode composition is especially crucial for conversion reaction-based materials where the composite electrode (active material, conducting additive and binder) has to buffer the huge volume change occurring upon cycling. This work highlights the differences observed on Sn-CMC electrode performance by using different Sn particle sizes (micro- and nanoparticles) and evaluating the role of the conductive additive in the electrode. Carbon fibers (VGCF) demonstrate a good ability to surround micrometer particles but not especially nanometer particles leading to an improvement in the performance of microparticles but not of nanoparticles. For a high loading electrode suitable for full cell applications (>3.5 mg/cm(2) of active material), nanometer particles show limited performance for long-term cycling. The combination of VGCF with micrometer particles seems to be the most promising composition to obtain good performances for conversion reaction based-materials.

  19. Conductive lithium storage electrode

    DOEpatents

    Chiang, Yet-Ming; Chung, Sung-Yoon; Bloking, Jason T; Andersson, Anna M

    2014-10-07

    A compound comprising a composition A.sub.x(M'.sub.1-aM''.sub.a).sub.y(XD.sub.4).sub.z, A.sub.x(M'.sub.1-aM''.sub.a).sub.y(DXD.sub.4).sub.z, or A.sub.x(M'.sub.1-aM''.sub.a).sub.y(X.sub.2D.sub.7).sub.z, (A.sub.1-aM''.sub.a).sub.xM'.sub.y(XD.sub.4).sub.z, (A.sub.1-aM''.sub.a).sub.xM'.sub.y(DXD.sub.4).sub.z, or (A.sub.1-aM''.sub.a).sub.xM'.sub.y(X.sub.2D.sub.7).sub.z. In the compound, A is at least one of an alkali metal and hydrogen, M' is a first-row transition metal, X is at least one of phosphorus, sulfur, arsenic, molybdenum, and tungsten, M'' any of a Group IIA, IIIA, IVA, VA, VIA, VIIA, VIIIA, IB, IIB, IIIB, IVB, VB, and VIB metal, D is at least one of oxygen, nitrogen, carbon, or a halogen, 0.0001electrodes and storage batteries.

  20. Cyanex based uranyl sensitive polymeric membrane electrodes.

    PubMed

    Badr, Ibrahim H A; Zidan, W I; Akl, Z F

    2014-01-01

    Novel uranyl selective polymeric membrane electrodes were prepared using three different low-cost and commercially available Cyanex extractants namely, bis(2,4,4-trimethylpentyl) phosphinic acid [L1], bis(2,4,4-trimethylpentyl) monothiophosphinic acid [L2] and bis(2,4,4-trimethylpentyl) dithiophosphinic acid [L3]. Optimization and performance characteristics of the developed Cyanex based polymer membrane electrodes were determined. The influence of membrane composition (e.g., amount and type of ionic sites, as well as type of plasticizer) on potentiometric responses of the prepared membrane electrodes was studied. Optimized Cyanex-based membrane electrodes exhibited Nernstian responses for UO₂(2+) ion over wide concentration ranges with fast response times. The optimized membrane electrodes based on L1, L2 and L3 exhibited Nernstian responses towards uranyl ion with slopes of 29.4, 28.0 and 29.3 mV decade(-1), respectively. The optimized membrane electrodes based on L1-L3 showed detection limits of 8.3 × 10(-5), 3.0 × 10(-5) and 3.3 × 10(-6) mol L(-1), respectively. The selectivity studies showed that the optimized membrane electrodes exhibited high selectivity towards UO₂(2+) ion over large number of other cations. Membrane electrodes based on L3 exhibited superior potentiometric response characteristics compared to those based on L1 and L2 (e.g., widest linear range and lowest detection limit). The analytical utility of uranyl membrane electrodes formulated with Cyanex extractant L3 was demonstrated by the analysis of uranyl ion in different real samples for nuclear safeguards verification purposes. The results obtained using direct potentiometry and flow-injection methods were compared with those measured using the standard UV-visible and inductively coupled plasma spectroscopic methods.