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Sample records for composite electrode applications

  1. 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.

  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. Manganese dioxide graphite composite electrodes: application to the electroanalysis of hydrogen peroxide, ascorbic acid and nitrite.

    PubMed

    Langley, Cathryn E; Sljukić, Biljana; Banks, Craig E; Compton, Richard G

    2007-02-01

    The modification of carbon powder with manganese dioxide using a wet impregnation procedure with electrochemical characterisation of the modified powder is described. The process involves saturation of the carbon powder with manganese(II) nitrate followed by thermal treatment at ca. 773 K leading to formation of manganese(IV) oxide on the surface of the carbon powder. The construction of composite electrodes based on manganese dioxide modified carbon powder and epoxy resin is also described, including optimisation of the percentage of the modified carbon powder. Composite electrodes showed attractive performances for electroanalytical applications, proving to be suitable for the electrochemical detection of hydrogen peroxide, ascorbic acid and nitrite ions with limits of detection comparable to the detection limits achieved by other analytical techniques. The results obtained for detection of these analytes, together with composite electrodes flexible design and low cost offers potential application of composite electrodes in biosensors.

  4. 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.

  5. 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.

  6. 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.

  7. 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. PMID:27483800

  8. 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.

  9. 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.

  10. Carbon felt supported carbon nanotubes catalysts composite electrode for vanadium redox flow battery application

    NASA Astrophysics Data System (ADS)

    Wei, Guanjie; Jia, Chuankun; Liu, Jianguo; Yan, Chuanwei

    2012-12-01

    A modified electrode for vanadium redox flow battery (VRFB) has been developed in this paper. The electrode is based on a traditional carbon felt (CF) grafted with the short-carboxylic multi-walled carbon nanotubes (MWCNTs). The microstructure and electrochemical property of the modified electrode as well as the performance of the VRFB single cell with it have been characterized. The results show that the MWCNTs are evenly dispersed and adhere to the surface of carbon fibres in the CF. The electrochemical activities of the modified CF electrode have been improved dramatically and the reversibility of the VO2+/VO2+ and V3+/V2+ redox couples increased greatly. The VRFB single cell with the modified CF exhibits higher coulombic efficiency (93.9%) and energy efficiency (82.0%) than that with the pristine CF. The SEM analysis shows that the MWCNTs still cohere with carbon fibres after charge and discharge test, indicating the stability of the MWCNTs in flowing electrolyte. Therefore, the composite electrode presents considerable potential for the commercial application of CF in VRFB.

  11. Application of a multiwalled carbon nanotube-chitosan composite as an electrode in the electrosorption process for water purification.

    PubMed

    Ma, Chih-Yu; Huang, Shih-Ching; Chou, Pei-Hsin; Den, Walter; Hou, Chia-Hung

    2016-03-01

    In this study, a multiwalled carbon nanotubes-chitosan (CNTs-CS) composite electrode was fabricated to enable water purification by electrosorption. The CNTs-CS composite electrode was shown to possess excellent capacitive behaviors and good pore accessibility by electrochemical impedance spectroscopy, galvanostatic charge-discharge, and cyclic voltammetry measurements in 1 M H2SO4 electrolyte. Moreover, the CNTs-CS composite electrode showed promising performance for capacitive water desalination. At an electric potential of 1.2 V, the electrosorption capacity and electrosorption rate of NaCl ions on the CNTs-CS composite electrode were determined to be 10.7 mg g(-1) and 0.051 min(-1), respectively, which were considerably higher than those of conventional activated electrodes. The improved electrosorption performance could be ascribed to the existence of mesopores. Additionally, the feasibility of electrosorptive removal of aniline from an aqueous solution has been demonstrated. Upon polarization at 0.6 V, the CNTs-CS composite electrode had a larger electrosorption capacity of 26.4 mg g(-1) and a higher electrosorption rate of 0.006 min(-1) for aniline compared with the open circuit condition. The enhanced adsorption resulted from the improved affinity between aniline and the electrode under electrochemical assistance involving a nonfaradic process. Consequently, the CNT-CS composite electrode, exhibiting typical double-layer capacitor behavior and a sufficient potential range, can be a potential electrode material for application in the electrosorption process.

  12. Method for uniformly distributing carbon flakes in a positive electrode, the electrode made thereby and compositions. [Patent application

    DOEpatents

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

    1981-01-19

    A positive electrode for a secondary electrochemical cell is described 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.

  13. 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.

  14. Flexible multiwalled carbon nanotubes/conductive polymer composite electrode for supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Lee, Ka Yeung Terence; Shi, HaoTian Harvey; Lian, Keryn; Naguib, Hani E.

    2015-11-01

    The electrode performance of three types of selected electrically conductive polymers (ECPs), namely polyaniline, polypyrrole (PPy) and poly(3, 4-ethylenedioxythiophene) PEDOT (PSS:PEDOT) composite with multiwalled carbon nanotubes (MWCNTs) were investigated in this study. The capacitor electrode performance has been examined in both three electrodes half-cell and two electrodes device setups. The nano-composites were fabricated via polymerization of pseudocapacitive conductive monomer onto the MWCNT surface through the in situ chemical polymerization approach. Stainless steel thin foils were used as a current collector as well as a flexible backbone. Graphite conductive ink was used as the binder with the composite powder to form a conductive electrode layer. Half-cell electrochemical study was conducted to optimize the weight proportion between MWCNT and ECP in this parametric study. Two-electrode cell electrochemical study assessed the potential performance for the device. MWCNT was found to serve as the framework for polymerization of the ECP into a tubular structure. Among the three composites, it was discovered that the PPy/MWCNT composite has superior capacitor performance up to scan rate of 500 mV s-1.

  15. 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.

  16. Investigation of the properties of polyacrylamide-polyaniline composite and its application as a battery electrode

    SciTech Connect

    Bhat, N.V.; Joshi, N.V. . Dept. of Chemical Technology)

    1993-11-20

    The composite films of polyacrylamide and polyaniline were prepared by polymerizing aniline using ammonium persulfate as an initiator in an aqueous solution containing poly-acrylamide. A film was then cast from this solution. The structural, dynamic mechanical, electrical, and thermal properties of these films have been studied. The infrared spectrum shows the presence of polyacrylamide as well as polyaniline in the composite film. The thermal analysis shows that the composite degrades slower than does the polyacrylamide alone. The dynamic mechanical analysis indicates that there is an increase in the glass transition temperature after the composite formation. The electrical conductivity has been found to increase by more than eight orders of magnitude. These composite films have also been suitably used as electrodes in secondary batteries.

  17. Fabrication and Electrochemical Characterization of Polyaniline/Titanium Oxide Nanoweb Composite Electrode for Supercapacitor Application.

    PubMed

    Yu, Hyunuk; Jang, Kihun; Chung, Ildoo; Ahn, Heejoon

    2016-03-01

    In this study, polyaniline/titanium oxide (PANi-TiO2) nanoweb composite was fabricated through electrochemical deposition and electrospinning techniques, and the composite was further utilized as an electrode for a supercapacitor. The PANi-TiO2 composite film showed three-dimensional hierarchical micro/nano architecture. The film was deposited on the current collector without the use of any binders. The morphology of the PANi-TiO2 composite film was confirmed by the use of field emission scanning electron microscopy (FE-SEM) analysis that polyaniline was grown in the form of nanorods with a diameter of 100 nm-200 nm on a TiO2 nanoweb. The chemical composition and quantitative analysis were determined by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The electrochemical properties were analyzed by cyclic voltammetry (CV), chronopotentiometry, and electrochemical impedance spectroscopy (EIS). The result of electrochemical tests indicated that TiO2-PANi electrode displayed a high specific capacitance of 306.5 Fg(-1) at the scan rate of 20 mVs(-1), with the capacitance retention ratio being 103% after 500 cycles at the scan rate of 50 mVs(-1).

  18. Fabrication and application of flexible graphene silk composite film electrodes decorated with spiky Pt nanospheres.

    PubMed

    Liang, Bo; Fang, Lu; Hu, Yichuan; Yang, Guang; Zhu, Qin; Ye, Xuesong

    2014-04-21

    A free-standing graphene silk composite (G/S) film was fabricated via vacuum filtration of a mixed suspension of graphene oxide and silk fibres, followed by chemical reduction. Spiky structured Pt nanospheres were grown on the film substrate by cyclic voltammetry electrodeposition. The electrical and mechanical performance of a single graphene coated silk fibre was investigated. The conductivity of a single graphene coated silk fibre is 57.9 S m(-1). During 1000 bending measurements, the conductivity was stable and showed negligible variation. The G/S film has a sheet resistivity of 90 Ω □(-1) with a porous and hierarchical structure. The spiky Pt nanosphere decorated G/S film was directly used as a H₂O₂ electrode with a sensitivity of 0.56 mA mM(-1) cm(-2), a linear range of 0-2.5 mM and an ultralow detection limit of 0.2 μM (S/N = 3). A glucose biosensor electrode was further fabricated by enzyme immobilization. The results show a sensitivity of 150.8 μA mM(-1) cm(-2) and a low detection limit of 1 μM (S/N = 3) for glucose detection. The strategy of coating graphene sheets on a silk fibre surface provides a new approach for developing electrically conductive biomaterials, tissue engineering scaffolds, bendable electrodes, and wearable biomedical devices.

  19. Carbon Fiber/Epoxy Composite Ring-disk Electrode: Fabrication, Characterization and Application to Electrochemical Detection in Capillary High Performance Liquid Chromatography.

    PubMed

    Xu, Xiaomi; Weber, Stephen G

    2009-05-15

    Carbon fiber/epoxy composite materials, which are manufactured using the pultrusion process, are commercially available in various shapes and sizes at very low cost. Here we demonstrate the application of such a material as an electrochemical detector in a flow system. Cyclic voltammetry shows that the material's electrochemical behavior resembles that of glassy carbon. Using tube and rod composites, we successfully fabricated a ring-disk electrode with a 20 μm gap between the ring and the disk. The narrow gap is favorable for mass transfer in the generator-collector experiment. This composite ring-disk electrode is assembled in a thin-layer radial-flow cell and used as an electrochemical detector. The disk electrode, placed directly opposite to the flow inlet, is operated as a generator electrode with the ring electrode being a collector. The high collection efficiency on the ring electrode (0.8 for a chemically reversible species) enhances the detection selectivity.

  20. Carbon Fiber/Epoxy Composite Ring-disk Electrode: Fabrication, Characterization and Application to Electrochemical Detection in Capillary High Performance Liquid Chromatography

    PubMed Central

    Xu, Xiaomi

    2009-01-01

    Carbon fiber/epoxy composite materials, which are manufactured using the pultrusion process, are commercially available in various shapes and sizes at very low cost. Here we demonstrate the application of such a material as an electrochemical detector in a flow system. Cyclic voltammetry shows that the material's electrochemical behavior resembles that of glassy carbon. Using tube and rod composites, we successfully fabricated a ring-disk electrode with a 20 μm gap between the ring and the disk. The narrow gap is favorable for mass transfer in the generator-collector experiment. This composite ring-disk electrode is assembled in a thin-layer radial-flow cell and used as an electrochemical detector. The disk electrode, placed directly opposite to the flow inlet, is operated as a generator electrode with the ring electrode being a collector. The high collection efficiency on the ring electrode (0.8 for a chemically reversible species) enhances the detection selectivity. PMID:20160941

  1. Electrochemical Properties of Graphene Oxide/Resol Composites as Electrode Materials for Supercapacitor Applications.

    PubMed

    Park, Geon Woo; Jeon, Sang Kwon; Yang, Jin Yong; Choi, Sung Dae; Kim, Geon Joong

    2016-05-01

    RGO/Resol carbon composites were prepared from a mixture of reduced GO and a low-molecular-weight phenolic resin (Resol) solution. The effects of the calcination temperature, amount of Resol added and KOH treatment on the electrochemical performance of the RGO/Resol composites were investigated. The physical and electrochemical properties of the composite materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) surface areas measurements, and cyclic voltammetry (CV). The relationships between their physical properties and their electrochemical performance were examined for use as super-capacitors (SCs). The RGO/Resol composite calcined at 400 degrees C after the KOH loading showed dramatically improved electrochemical properties, showing a high BET surface and capacitance of 2190 m2/g and 220 F/g, respectively. The RGO/Resol composites calcined after the KOH treatment showed much better capacitor performance than those treated only thermally at the same temperature without KOH impregnation. The fabrication of high surface electrodes was essential for improving the SCs properties. PMID:27483752

  2. Electrochemical Properties of Graphene Oxide/Resol Composites as Electrode Materials for Supercapacitor Applications.

    PubMed

    Park, Geon Woo; Jeon, Sang Kwon; Yang, Jin Yong; Choi, Sung Dae; Kim, Geon Joong

    2016-05-01

    RGO/Resol carbon composites were prepared from a mixture of reduced GO and a low-molecular-weight phenolic resin (Resol) solution. The effects of the calcination temperature, amount of Resol added and KOH treatment on the electrochemical performance of the RGO/Resol composites were investigated. The physical and electrochemical properties of the composite materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) surface areas measurements, and cyclic voltammetry (CV). The relationships between their physical properties and their electrochemical performance were examined for use as super-capacitors (SCs). The RGO/Resol composite calcined at 400 degrees C after the KOH loading showed dramatically improved electrochemical properties, showing a high BET surface and capacitance of 2190 m2/g and 220 F/g, respectively. The RGO/Resol composites calcined after the KOH treatment showed much better capacitor performance than those treated only thermally at the same temperature without KOH impregnation. The fabrication of high surface electrodes was essential for improving the SCs properties.

  3. Fabrication and application of flexible graphene silk composite film electrodes decorated with spiky Pt nanospheres

    NASA Astrophysics Data System (ADS)

    Liang, Bo; Fang, Lu; Hu, Yichuan; Yang, Guang; Zhu, Qin; Ye, Xuesong

    2014-03-01

    A free-standing graphene silk composite (G/S) film was fabricated via vacuum filtration of a mixed suspension of graphene oxide and silk fibres, followed by chemical reduction. Spiky structured Pt nanospheres were grown on the film substrate by cyclic voltammetry electrodeposition. The electrical and mechanical performance of a single graphene coated silk fibre was investigated. The conductivity of a single graphene coated silk fibre is 57.9 S m-1. During 1000 bending measurements, the conductivity was stable and showed negligible variation. The G/S film has a sheet resistivity of 90 Ω □-1 with a porous and hierarchical structure. The spiky Pt nanosphere decorated G/S film was directly used as a H2O2 electrode with a sensitivity of 0.56 mA mM-1 cm-2, a linear range of 0-2.5 mM and an ultralow detection limit of 0.2 μM (S/N = 3). A glucose biosensor electrode was further fabricated by enzyme immobilization. The results show a sensitivity of 150.8 μA mM-1 cm-2 and a low detection limit of 1 μM (S/N = 3) for glucose detection. The strategy of coating graphene sheets on a silk fibre surface provides a new approach for developing electrically conductive biomaterials, tissue engineering scaffolds, bendable electrodes, and wearable biomedical devices.A free-standing graphene silk composite (G/S) film was fabricated via vacuum filtration of a mixed suspension of graphene oxide and silk fibres, followed by chemical reduction. Spiky structured Pt nanospheres were grown on the film substrate by cyclic voltammetry electrodeposition. The electrical and mechanical performance of a single graphene coated silk fibre was investigated. The conductivity of a single graphene coated silk fibre is 57.9 S m-1. During 1000 bending measurements, the conductivity was stable and showed negligible variation. The G/S film has a sheet resistivity of 90 Ω □-1 with a porous and hierarchical structure. The spiky Pt nanosphere decorated G/S film was directly used as a H2O2 electrode with a

  4. Electrodes for microfluidic applications

    DOEpatents

    Crocker, Robert W.; Harnett, Cindy K.; Rognlien, Judith L.

    2006-08-22

    An electrode device for high pressure applications. These electrodes, designed to withstand pressure of greater than 10,000 psi, are adapted for use in microfluidic devices that employ electrokinetic or electrophoretic flow. The electrode is composed, generally, of an outer electrically insulating tubular body having a porous ceramic frit material disposed in one end of the outer body. The pores of the porous ceramic material are filled with an ion conductive polymer resin. A conductive material situated on the upper surface of the porous ceramic frit material and, thus isolated from direct contact with the electrolyte, forms a gas diffusion electrode. A metal current collector, in contact with the gas diffusion electrode, provides connection to a voltage source.

  5. Composite electrodes for electrochemical supercapacitors.

    PubMed

    Li, Jun; Yang, Quanmin; Zhitomirsky, Igor

    2010-01-07

    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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Application of three-dimensional reduced graphene oxide-gold composite modified electrode for direct electrochemistry and electrocatalysis of myoglobin.

    PubMed

    Shi, Fan; Xi, Jingwen; Hou, Fei; Han, Lin; Li, Guangjiu; Gong, Shixing; Chen, Chanxing; Sun, Wei

    2016-01-01

    In this paper a three-dimensional (3D) reduced graphene oxide (RGO) and gold (Au) composite was synthesized by electrodeposition and used for the electrode modification with carbon ionic liquid electrode (CILE) as the substrate electrode. Myoglobin (Mb) was further immobilized on the surface of 3D RGO-Au/CILE to obtain an electrochemical sensing platform. Direct electrochemistry of Mb on the modified electrode was investigated with a pair of well-defined redox waves appeared on cyclic voltammogram, indicating the realization of direct electron transfer of Mb with the modified electrode. The results can be ascribed to the presence of highly conductive 3D RGO-Au composite on the electrode surface that accelerate the electron transfer rate between the electroactive center of Mb and the electrode. The Mb modified electrode showed excellent electrocatalytic activity to the reduction of trichloroacetic acid in the concentration range from 0.2 to 36.0 mmol/L with the detection limit of 0.06 mmol/L (3σ).

  11. 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

  12. Graphene decorated with MoS2 nanosheets: a synergetic energy storage composite electrode for supercapacitor applications.

    PubMed

    Thangappan, R; Kalaiselvam, S; Elayaperumal, A; Jayavel, R; Arivanandhan, M; Karthikeyan, R; Hayakawa, Y

    2016-02-14

    The two-dimensional (2D) transition metal dichalcogenide nanosheet-carbon composite is an attractive material for energy storage because of its high Faradaic activity, unique nanoconstruction and electronic properties. In this work, a facile one step preparation of a molybdenum disulfide (MoS2) nanosheet-graphene (MoS2/G) composite with the in situ reduction of graphene oxide is reported. The structure, morphology and composition of the pure MoS2 and composites were comparatively analyzed by various characterization techniques. The electrochemical performance of the pure MoS2, graphene oxide and the MoS2/G composite electrode materials was evaluated by cyclic voltammogram, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The MoS2/G composite showed a higher specific capacitance (270 F g(-1) at a current density of 0.1 A g(-1)) compared to the pure MoS2 (162 F g(-1)) in a neutral aqueous electrolyte. Moreover, the energy density of the composite electrode is also higher (12.5 Wh kg(-1)) with a high power density (2500 W kg(-1)) compared to the pure MoS2. In addition, the MoS2/G composite electrode showed excellent cyclic stability even after 1000 cycles. The enhancement in specific capacitance, excellent cyclic stability and high energy density of the composite electrode are mainly due to the interconnected conductive network of the composite as well as the synergetic effect of the pure MoS2 and graphene. The experimental results demonstrated that the MoS2/G composite is a promising electrode material for high-performance supercapacitors.

  13. Recent developments in the NSWC composite electrode

    NASA Technical Reports Server (NTRS)

    Ferrando, W. A.

    1982-01-01

    A characterization of the physical parameters and life cycle data on nickel composite electrodes was conducted. Attempts to improve the nickel composite electrodes with respect to longevity, light weight, and low cost were made. The physical characteristics of a group of electrodes were examined with emphasis on the porosity of the plaques, the thickness of the electrodes, and the potential presence of electrolytes contamination. It was concluded that the nickel composite electrodes exhibit good life cycle characteristics and that their fabrication seems to present real possibilities for the future as a method of making electrodes that are durable, lightweight, and low cost.

  14. Recent developments in the NSWC composite electrode

    NASA Astrophysics Data System (ADS)

    Ferrando, W. A.

    1982-03-01

    A characterization of the physical parameters and life cycle data on nickel composite electrodes was conducted. Attempts to improve the nickel composite electrodes with respect to longevity, light weight, and low cost were made. The physical characteristics of a group of electrodes were examined with emphasis on the porosity of the plaques, the thickness of the electrodes, and the potential presence of electrolytes contamination. It was concluded that the nickel composite electrodes exhibit good life cycle characteristics and that their fabrication seems to present real possibilities for the future as a method of making electrodes that are durable, lightweight, and low cost.

  15. 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.

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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 H2SO4 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-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-1, i.e. for the cell with the resistance of 15 Ohm and composite electrode consists of 5 % ruthenium oxide.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Ionic polymer metal composites with polypyrrole-silver electrodes

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  11. 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.

  12. Conductor-polymer composite electrode materials

    DOEpatents

    Ginley, D.S.; Kurtz, S.R.; Smyrl, W.H.; Zeigler, J.M.

    1984-06-13

    A conductive composite material useful as an electrode, comprises a conductor and an organic polymer which is reversibly electrochemically dopable to change its electrical conductivity. Said polymer continuously surrounds the conductor in intimate electrical contact therewith and is prepared by electrochemical growth on said conductor or by reaction of its corresponding monomer(s) on said conductor which has been pre-impregnated or pre-coated with an activator for said polymerization. Amount of the conductor is sufficient to render the resultant composite electrically conductive even when the polymer is in an undoped insulating state.

  13. Synthesis and characterization of a novel hybrid nano composite cation exchanger poly-o-toluidine Sn(IV) tungstate: Its analytical applications as ion-selective electrode

    NASA Astrophysics Data System (ADS)

    Khan, Asif Ali; Shaheen, Shakeeba

    2013-02-01

    A novel organic-inorganic nano composite cation exchanger poly-o-toluidine Sn(IV) tungstate has been synthesized by incorporation of a polymer material into inorganic precipitate. The material is a class of hybrid ion-exchanger with good ion-exchange properties, reproducibility, stability and good selectivity for heavy metals. The physico-chemical properties of this nano composite material were characterized by using XRD, TGA, FTIR, SEM and TEM. The ion-exchange capacity, pH titrations, elution behavior and chemical stability were also carried out to study ion-exchange properties of the material. Distribution studies for various metal ions revealed that the nano composite is highly selective for Cd(II). An ion-selective membrane electrode was fabricated using this material for the determination of Cd(II) ions in solutions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations.

  14. Evaluation of commercial lithium-ion cells based on composite positive electrode for plug-in hybrid electric vehicle applications. Part I: Initial characterizations

    SciTech Connect

    Matthieu Dubarry; Cyril Truchot; Mikael Cugnet; Bor Yann Liaw; Kevin Gering; Sergiy Sazhin; David Jamison; Christopher Michelbacher

    2011-12-01

    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 (LiMn1/3Ni1/3Co1/3O2 + LiMn2O4) 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.

  15. Investigation of Ice-Templated Porous Electrodes for Application in Organic Batteries.

    PubMed

    Stolze, Christian; Janoschka, Tobias; Flauder, Stefan; Müller, Frank A; Hager, Martin D; Schubert, Ulrich S

    2016-09-14

    Application and investigation of porous composite electrodes for organic batteries fabricated by an ice-templating method are reported for the first time. The possibility to produce polymer composite electrodes with highly aligned, parallel pores is demonstrated and electrochemical investigations are presented to examine their suitability for application in organic batteries. The performance of such ice-templated porous electrodes is experimentally compared with planar electrodes of similar composition against zinc and lithium counter electrodes, respectively. Fundamental properties limiting the performance of ice-templated porous electrodes are discussed and further means to overcome those limitations are proposed. PMID:27570872

  16. Investigation of Ice-Templated Porous Electrodes for Application in Organic Batteries.

    PubMed

    Stolze, Christian; Janoschka, Tobias; Flauder, Stefan; Müller, Frank A; Hager, Martin D; Schubert, Ulrich S

    2016-09-14

    Application and investigation of porous composite electrodes for organic batteries fabricated by an ice-templating method are reported for the first time. The possibility to produce polymer composite electrodes with highly aligned, parallel pores is demonstrated and electrochemical investigations are presented to examine their suitability for application in organic batteries. The performance of such ice-templated porous electrodes is experimentally compared with planar electrodes of similar composition against zinc and lithium counter electrodes, respectively. Fundamental properties limiting the performance of ice-templated porous electrodes are discussed and further means to overcome those limitations are proposed.

  17. Magnetoelectric thin film composites with interdigital electrodes

    NASA Astrophysics Data System (ADS)

    Piorra, A.; Jahns, R.; Teliban, I.; Gugat, J. L.; Gerken, M.; Knöchel, R.; Quandt, E.

    2013-07-01

    Magnetoelectric (ME) thin film composites on silicon cantilevers are fabricated using Pb(Zr0.52Ti0.45)O3 (PZT) films with interdigital transducer electrodes on the top side and FeCoSiB amorphous magnetostrictive thin films on the backside. These composites without any direct interface between the piezoelectric and magnetostrictive phase are superior to conventional plate capacitor-type thin film ME composites. A limit of detection of 2.6 pT/Hz1/2 at the mechanical resonance is determined which corresponds to an improvement of a factor of approximately 2.8 compared to the best plate type sensor using AlN as the piezoelectric phase and even a factor of approximately 4 for a PZT plate capacitor.

  18. 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.

  19. 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

  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. Determination of trace amounts of lead and cadmium using a bismuth/glassy carbon composite electrode.

    PubMed

    Hwang, Gil-Ho; Han, Won-Kyu; Hong, Seok-Jun; Park, Joon-Shik; Kang, Sung-Goon

    2009-02-15

    We examined the use of a bismuth-glassy carbon (Bi/C) composite electrode for the determination of trace amounts of lead and cadmium. Incorporated bismuth powder in the composite electrode was electrochemically dissolved in 0.1M acetate buffer (pH 4.5) where nanosized bismuth particles were deposited on the glassy carbon at the reduction potential. The anodic stripping voltammetry on the Bi/C composite electrode exhibited well-defined, sharp and undistorted peaks with a favorable resolution for lead and cadmium. Comparing a non-oxidized Bi/C composite electrode with an in-situ plated bismuth film electrode, the Bi/C composite electrode exhibited superior performance due to its much larger surface area. The limit of detection was 0.41 microg/L for lead and 0.49 microg/L for cadmium. Based on this study, we are able to conclude that various types of composite electrodes for electroanalytical applications can be developed with a prudent combination of electrode materials.

  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. Compliant composite electrodes and large strain bistable actuation

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    Dielectric elastomer actuators (DEA) and bistable electroactive polymers (BSEP) both require compliant electrodes with rubbery elasticity and high conductivity at large strains. Stretchable opto-electronic devices additionally require the compliant electrodes to be optically transparent. Many candidate materials have been investigated. We report a new approach to mechanically robust, stretchable compliant electrodes. A facile in-situ composite synthesis and transfer technique is employed, and the resulting composite electrodes retain the high surface conductivity of the original conductive network formed by nanowires or nanotubes, while exhibiting the mechanical flexibility of the matrix polymer. The composite electrodes have high transparency and low surface roughness useful for the fabrication of polymer thinfilm electronic devices. The new electrodes are suitable for high-strain actuation, as a complaint resistive heating element to administer the temperature of shape memory polymers, and as the charge injection electrodes for flexible/stretchable polymer light emitting diodes. Bistable electroactive polymers employing the composite electrodes can be actuated to large strains via heating-actuation-cooling cycles.

  5. Transparent composite electrode for high-efficiency polymer LEDs

    NASA Astrophysics Data System (ADS)

    Li, Lu; Yu, Zhibin; Liang, Jiajie; Chang, Chia-Hao; Hu, Weili; Pei, Qibing

    2012-09-01

    Polymer composite electrodes based on silver nanowires or carbon nanotubes have been prepared with transparency and surface conductivity approaching those of ITO/glass and better than ITO/PET. The conductive surface has an average roughness less than 10 nm, better than ITO/glass. Depending on the polymer matrix selected, the composite electrodes can be made rigid, flexible like polycarbonate, or stretchable like a rubber. Various polymer light emitting diodes,light emitting electrochemical cells and polymer solar cells have been fabricated using the composite electrode as anode, exhibiting electroluminescent efficiencies generally higher than control devices fabricated on ITO/glass. These polymer light emitting devices are all highly flexible and can be bent to less than 3 mm radius without loss of performance. With further modification of the composite electrodes, we have also demonstrated stretchable OLEDs wherein the emissive area can be elongated by as much as 50%.

  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. Amperometric determination of hydrazine at manganese hexacyanoferrate modified graphite-wax composite electrode.

    PubMed

    Jayasri, D; Narayanan, S Sriman

    2007-06-01

    Fabrication, characterization and application of a manganese hexacyanoferrate (MnHCF) modified graphite-wax composite electrode are described. The MnHCF mixed with graphite powder was dispersed into molten paraffin wax to yield a conductive composite, which was used as electrode material to construct a renewable three-dimensional MnHCF modified electrode. The characterization of the modified electrode has been studied by electrochemical techniques. The cyclic voltammogram of the MnHCF modified graphite-wax composite electrode prepared under optimum composition, showed a well-defined redox couple due to Fe(CN)(6)(4-)/Fe(CN)(6)(3-) system. The electrocatalytic oxidation of hydrazine by MnHCF modified graphite-wax composite electrode has been investigated in an attempt to develop a new sensor for its determination. It was found that the mediator catalyzed the oxidation of hydrazine. The electrocatalytic oxidation of hydrazine was also studied under hydrodynamic and chronoamperometric conditions. The anodic current increases linearly with increase in the concentration of hydrazine in the range of 3.33x10(-5)M to 8.18x10(-3)M. The detection limit was found to be 6.65x10(-6)M (S/N=3). The modified electrode can also be used for on-line detection of hydrazine. The proposed method has also been applied for the determination of hydrazine in photographic developer solution.

  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. Polymer-graphite composite: a versatile use and throw plastic chip electrode.

    PubMed

    Perween, Mosarrat; Parmar, Dilip B; Bhadu, Gopala Ram; Srivastava, Divesh N

    2014-11-21

    We report an efficient plastic chip electrode (PCE) fabricated from a composite of graphite and poly(methyl methacrylate) by a simple solution casting method and promoted as an economically inexpensive, multipurpose disposable electrode for various applications. The TEM images of the filler (graphite) show that the material consists of single, as well as multi-layers. Thus, the self-standing and arid electrodes prepared were characterized for their material properties such as, microscopy (SEM and AFM), as well as thermal properties (TGA), mechanical (tensile strength) and electrical properties. A set of physical parameters were derived from these characterizations for sustainability of these electrodes in harsh off-laboratory conditions. The utility of these mechanically stable, bulk-conducting and high surface area electrodes were demonstrated in various well understood electrochemical protocols, such as cyclic voltammetry, stripping voltammetry, electropolymerization, electrowinning and amperometric sensing. The voltammetry data were compared with the data recorded on a conventional glassy carbon electrode. PMID:25248864

  11. 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.

  12. Electrochemical fabrication of metallic nanostructured electrodes for electroanalytical applications.

    PubMed

    Plowman, Blake J; Bhargava, Suresh K; O'Mullane, Anthony P

    2011-12-21

    The use of electrodeposited metal-based nanostructures for electroanalytical applications has recently received widespread attention. There are several approaches to creating nanostructured materials through electrochemical routes that include facile electrodeposition at either untreated or modified electrodes, or through the use of physical or chemical templating methods. This allows the shape, size and composition of the nanomaterial to be readily tuned for the application of interest. The use of such materials is particularly suited to electroanalytical applications. In this mini-review an overview of recently developed nanostructured materials developed through electrochemical routes is presented as well as their electroanalytical applications in areas of biological and environmental importance.

  13. [Remediation of chromium (VI) contaminated soils using permeable reactive composite electrodes technology].

    PubMed

    Fu, Rong-Bing; Liu, Fang; Ma, Jin; Zhang, Chang-Bo; He, Guo-Fu

    2012-01-01

    Electrokinetic transport processes have been shown to have potential for the effective removal of heavy metals from soils. However, pH changes near the anode and cathode limit their widespread application in the remediation of contaminated soils. Permeable reactive composite electrodes (PRCE) were made by attaching reactive materials such as Fe(0) and zeolite to the electrodes, and the effects of the composite electrodes on pH control, chromium removal efficiency and Cr speciation changes were studied in the electrokinetic remediation process of Cr( VI) contaminated soil. Composite electrodes consisting of permeable reactive materials gave better pH control and Cr removal efficiency compared to traditional electrodes, and a Fe(0) + zeolite reactive layer in the anode exhibited the best performance compared to zeolite or Fe(0) alone. After 5 days of electrokinetic remediation with a DC voltage of 2 V x cm(-1), the Fe(0) + zeolite reactive layer lowered the pH fluctuation, maintained the soil pH in the range of 5.5 to 8.5, raised the Cr(VI) removal efficiency up to 97% in any soil section, produced lower Cr(III) residues, enhanced the amount of Cr retention up to 8 and 1.8 times respectively, and transformed 98% of the Cr(VI) into lower toxicity Cr(III). This study provides a theoretical basis for the exploitation of permeable reactive composite electrodes which are a practical option for future applications. PMID:22452223

  14. [Remediation of chromium (VI) contaminated soils using permeable reactive composite electrodes technology].

    PubMed

    Fu, Rong-Bing; Liu, Fang; Ma, Jin; Zhang, Chang-Bo; He, Guo-Fu

    2012-01-01

    Electrokinetic transport processes have been shown to have potential for the effective removal of heavy metals from soils. However, pH changes near the anode and cathode limit their widespread application in the remediation of contaminated soils. Permeable reactive composite electrodes (PRCE) were made by attaching reactive materials such as Fe(0) and zeolite to the electrodes, and the effects of the composite electrodes on pH control, chromium removal efficiency and Cr speciation changes were studied in the electrokinetic remediation process of Cr( VI) contaminated soil. Composite electrodes consisting of permeable reactive materials gave better pH control and Cr removal efficiency compared to traditional electrodes, and a Fe(0) + zeolite reactive layer in the anode exhibited the best performance compared to zeolite or Fe(0) alone. After 5 days of electrokinetic remediation with a DC voltage of 2 V x cm(-1), the Fe(0) + zeolite reactive layer lowered the pH fluctuation, maintained the soil pH in the range of 5.5 to 8.5, raised the Cr(VI) removal efficiency up to 97% in any soil section, produced lower Cr(III) residues, enhanced the amount of Cr retention up to 8 and 1.8 times respectively, and transformed 98% of the Cr(VI) into lower toxicity Cr(III). This study provides a theoretical basis for the exploitation of permeable reactive composite electrodes which are a practical option for future applications.

  15. 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.

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

    DOE PAGES

    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 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

  17. 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

  18. Synthesis, characterization and analytical application of nano-composite cation-exchange material, poly-o-toluidine Ce(IV) phosphate: Its application in making Cd(II) ion selective membrane electrode

    NASA Astrophysics Data System (ADS)

    Khan, Asif Ali; Akhtar, Tabassum

    2011-03-01

    An organic-inorganic composite, poly-o-toluidine Ce(IV) phosphate was chemically synthesized by mixing ortho-toluidine into the gel of Ce(IV) phosphate in different mixing volume ratios. Effect of eluant concentration, elution behavior and pH-titration studies were carried out to understand the ion-exchange capabilities. The physico-chemical properties of the material were determined using AAS, CHN elemental analysis, UV-VIS spectrophotometry, FTIR, SEM/EDX, TGA-DTA, TEM (Transmission electron microscopy), XRD and SEM studies. The distribution studies revealed that the cation-exchange material is highly selective for Cd(II). Due to selective nature of the cation-exchanger, ion selective membrane electrode was fabricated for the determination of Cd(ІІ) ions in solutions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations.

  19. 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.

  20. 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.

  1. Composition and function in AB{sub 5} hydride electrodes

    SciTech Connect

    Adzic, G.D.; Johnson, J.R.; Mukerjee, S.; McBreen, J.; Reilly, J.J.

    1996-12-31

    Multicomponent AB, hydrides are attractive replacements for the cadmium electrode in nickel - cadmium batteries. This paper is concerned with the differential effects of Ni substitution by cobalt, Mn and Al upon electrode corrosion and capacity, using alloys having the generic composition of Al(NiCoMnAl){sub 5} and similar to those used for the preparation of commercial battery electrodes. The corrosion of metal hydride electrodes is determined by two factors, surface passivation due to the presence of surface oxides or hydroxides and crystal lattice expansion - contraction the charge - discharge process. Thus, in addition to determining the effects of Ni substitution we will also address the question of whether an observed change is due to a change lattice expansion or to a change in surface passivation, e.g. the formation a corrosion resistant oxide layer.

  2. 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.

  3. Performance of suspension-impregnated sintered nickel composite electrodes

    SciTech Connect

    Ferrando, W.A.

    1985-10-01

    Direct impregnation for the development of a porous, sintered, nickel-plated graphite fiber plaque by fine particulate Ni(OH)2 is examined. The suspension impregnation method is described, noting that the entire process can be carried out in a very short time. The use of a cobalt additive to improve utilization and the life cycle of nickel electrodes is mentioned. It is found that the suspension method of active material impregnation has potential to produce high energy density, electrically durable, light weight nickel composite electrodes. It is also found that excellent life cycle durability results are obtained with the suspension-impregnated composite electrode. Finally, the electrochemical process, an alternative method of active material Ni(OH)2 impregnation, is mentioned.

  4. Exfoliated graphite-ruthenium oxide composite electrodes for electrochemical supercapacitors

    NASA Astrophysics Data System (ADS)

    Mitra, Sagar; Lokesh, K. S.; Sampath, S.

    The performance of exfoliated graphite (EG)-ruthenium oxide (RuO x) composites as binderless electrodes is evaluated for electrochemical capacitors (ECs). A composite of EG-RuO x is prepared by a modified sol-gel process. The material is characterized using X-ray diffraction and microscopy. Electrochemical capacitors with the composite electrodes in the presence of aqueous sulfuric acid (H 2SO 4) electrolyte are evaluated using voltammetry, impedance and charge-discharge studies. Cyclic voltammetry reveals very stable current-voltage behaviour up to several thousands of cycles, as well as high specific capacitances, e.g., a few hundreds of farads per gram for the composite that contains 16.5 wt.% RuO x.

  5. 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.

  6. Tailoring aerogel electrodes for electrochemical applications

    NASA Astrophysics Data System (ADS)

    Sakamoto, Jeffrey Steven

    2001-07-01

    The principal theme of the dissertation research was determining the relation between aerogel electrode morphology and electrochemical performance. Issues such as electrical wiring and mass transport in transition metal oxide, aerogel electrodes were addressed and designs were tailored for electrochemical applications. Single-wall carbon nanotubes were used to form the electronically conducting network in lithium intercalation electrodes that incorporated vanadium oxide aerogel as the active material. The similarities in morphology and dimensional scale for the nanotubes and V2O5 ribbons enabled excellent electrical contact to be made between the two phases without seriously affecting the aerogel nanostructure. The electrodes exhibited specific capacities in excess of 400 mAh/g at high discharge rates and retained this level of capacity on cycling. A second research goal was to improve mass transport within the aerogel electrode by minimizing tortuosity. In this research, hierarchically ordered vanadium oxide aerogel electrodes were designed and fabricated. The electrodes have two discrete and independent levels or porosity. At one level, ordered, interconnected macropores were fabricated using the templating process. At another level, interconnected mesopores were created using sol-gel synthesis and ambient drying. Electrochemical activity towards lithium was demonstrated using cyclic voltammetry and chronopotentiometry. These data are believed to be the first to demonstrate electrochemical activity for the class of materials based on the inverse opal structure. Several Group I cations and multivalent cations were reversibly, and electrochemically reacted with vanadium oxide aerogel. The molar capacities of the Group I elements (Na+ = 3.0 moles and K+ = 2.0) were high and comparable to Li+ (3.6 moles). Interestingly, the electron equivalent capacity for Mg2+ (4.0) was higher than Li+ and agrees well with the chemical titration capacity. Galvanostatic rate

  7. Inflatable belt for the application of electrode arrays

    NASA Astrophysics Data System (ADS)

    Sadleir, R. J.; Fox, R. A.; Turner, V. F.

    2000-02-01

    A prototype device for application of a multiple electrode array to the human abdomen is described and assessed. The device consists of a segmented pneumatic (PVC) belt that, upon inflation, presses electrodes onto the skin simultaneously and with predetermined relative spacings. A single belt can fit a wide range of subject sizes and is comfortable for subjects to wear. It may be useful under conditions where the time taken to attach electrodes is crucial—as in hospital emergency ward applications, and where the maintenance of constant relative electrode spacings is important. The noise performance of these electrodes was only slightly poorer than that obtained using adhesive ECG electrodes.

  8. 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

  9. Zinc oxide interdigitated electrode for biosensor application

    NASA Astrophysics Data System (ADS)

    Sin L., L.; Arshad, M. K. Md.; Fathil, M. F. M.; Adzhri, R.; M. Nuzaihan M., N.; Ruslinda, A. R.; Gopinath, Subash C. B.; Hashim, U.

    2016-07-01

    In biosensors, zinc oxide (ZnO) thin film plays a crucial role in term of stability, sensitivity, biocompatibility and low cost. Interdigitated electrode (IDE) design is one of the device architecture in biosensor for label free, stability and sensitivity. In this paper, we discuss the fabrication of zinc oxide deposited on the IDE as a transducer for sensing of biomolecule. The formation of APTES had increase the performance of the surface functionalization..Furthermore we extend the discuss on the surface functionalization process which is utilized for probe attachment onto the surface of biosensor through surface immobilization process, thus enables the sensing of biomolecules for biosensor application.

  10. Composite fiber structures for catalysts and electrodes

    NASA Technical Reports Server (NTRS)

    Marrion, Christopher J.; Cahela, Donald R.; Ahn, Soonho; Tatarchuk, Bruce J.

    1993-01-01

    We have recently envisioned a process wherein fibers of various metals in the 0.5 to 15 micron diameter range are slurried in concert with cellulose fibers and various other materials in the form of particulates and/or fibers. The resulting slurry is cast via a wet-lay process into a sheet and dried to produce a free-standing sheet of 'composite paper.' When the 'preform' sheet is sintered in hydrogen, the bulk of the cellulose is removed with the secondary fibers and/or particulates being entrapped by the sinter-locked network provided by the metal fibers. The resulting material is unique, in that it allows the intimate contacting and combination of heretofore mutually exclusive materials and properties. Moreover, due to the ease of paper manufacture and processing, the resulting materials are relatively inexpensive and can be fabricated into a wide range of three-dimensional structures. Also, because cellulose is both a binder and a pore-former, structures combining high levels of active surface area and high void volume (i.e., low pressure drop) can be prepared as freestanding flow through monoliths.

  11. Hexacyanoferrate-based composite ion-sensitive electrodes for voltammetry.

    PubMed

    Düssel, H; Dostal, A; Scholz, F

    1996-04-01

    Composite electrodes made of graphite, paraffin and metal hexacyanoferrates exhibit a voltammetric response of the hexacyanoferrate ions, the potential of which depends linearly on the logarithm of concentration of alkali and alkaline-earth metal ions. This behaviour has been observed on account of the fact that the electrochemical reaction is accompanied by an exchange of these ions between the solution and the zeolitic lattice of the hexacyanoferrates for charge compensation. The voltammetric determination of the formal potential of these electrodes in a solution allows the quantitative analysis of the ions which are exchanged between the metal hexacyanoferrates and the aqueous solutions. Iron(III), copper(II), silver(I), nickel(II) and cadmium(II) hexacyanoferrates have been studied for the determination of H(+), Li(+), Na(+), K(+), Rb(+), Cs(+), NH(+)(4), Mg(2+), Ca(2+) and Ba(2+). In some cases, the selectivity constants are as low as 3.10(-4), or even so small that their exact value is inaccessible. Electrodes made of iron (III), copper (II), silver (I), nickel (II) and cadmium (II) hexacyanoferrates are most suitable for the determination of potassium ions. Electrodes with nickel (II) and cadmium (II) hexacyanoferrates are also suitable for the determination of caesium ions. The working range of the electrodes also depends on the conductivity of the solutions and can range from 10(-5) to 1 mol l(-1). Typical standard deviations of the potential measurements are 3 mV.

  12. Indium- and Platinum-Free Counter Electrode for Green Mesoscopic Photovoltaics through Graphene Electrode and Graphene Composite Catalysts: Interfacial Compatibility.

    PubMed

    Yin, Jie; Zhou, Huawei; Liu, Zhicheng; Nie, Zhonghao; Li, Yinhao; Qi, Xuan; Chen, Baoli; Zhang, Yingtian; Zhang, Xianxi

    2016-03-01

    The scarcity and noble indium and platinum (Pt) are important elements in photoelectric nanomaterials. Therefore, development of low cost alternative materials to meet different practical applications is an urgent need. Two-dimensional (2D) layered graphene (GE) with unique physical, mechanical, and electrical properties has recently drawn a great deal of attention in various optoelectronic fields. Herein, the large scale (21 cm × 15 cm) high-quality single layer graphene (SLG) and multilayer graphene on a flexible plastic substrate PET were controllably prepared through layer-by-layer (LBL) transfer using the thermal release adhesive transfer method (TRA-TM). Transmission and antibending performance based on PET/GE were superior to traditional PET/ITO. The square resistance of a nine-layer graphene electrode reached approximately 58 Ω. Combined with our newly developed and highly effective Fe3O4@RGO (reduced graphene oxide) catalyst, the power conversion efficiency of the dye-sensitized solar cell (DSC) using flexible PET/GE conductive substrate was comparable to that of the DSC using the PET/ITO substrate. The desirable performance of PET/GE/Fe3O4@RGO counter electrodes (low-cost indium- and platinum-free counter electrodes) is attributed to the interfacial compatibility between 2D graphene composite catalyst (Fe3O4@RGO) and 2D PET/GE conductive substrate. In addition, DSCs that use only PET/GE (without Fe3O4@RGO catalyst) as counter electrodes can also achieve a photocurrent density of 6.30 mA cm(-2). This work is beneficial for fundamental research and practical applications of graphene and graphene composite in photovoltaics, photocatalytic water splitting, supercapacitors.

  13. Indium- and Platinum-Free Counter Electrode for Green Mesoscopic Photovoltaics through Graphene Electrode and Graphene Composite Catalysts: Interfacial Compatibility.

    PubMed

    Yin, Jie; Zhou, Huawei; Liu, Zhicheng; Nie, Zhonghao; Li, Yinhao; Qi, Xuan; Chen, Baoli; Zhang, Yingtian; Zhang, Xianxi

    2016-03-01

    The scarcity and noble indium and platinum (Pt) are important elements in photoelectric nanomaterials. Therefore, development of low cost alternative materials to meet different practical applications is an urgent need. Two-dimensional (2D) layered graphene (GE) with unique physical, mechanical, and electrical properties has recently drawn a great deal of attention in various optoelectronic fields. Herein, the large scale (21 cm × 15 cm) high-quality single layer graphene (SLG) and multilayer graphene on a flexible plastic substrate PET were controllably prepared through layer-by-layer (LBL) transfer using the thermal release adhesive transfer method (TRA-TM). Transmission and antibending performance based on PET/GE were superior to traditional PET/ITO. The square resistance of a nine-layer graphene electrode reached approximately 58 Ω. Combined with our newly developed and highly effective Fe3O4@RGO (reduced graphene oxide) catalyst, the power conversion efficiency of the dye-sensitized solar cell (DSC) using flexible PET/GE conductive substrate was comparable to that of the DSC using the PET/ITO substrate. The desirable performance of PET/GE/Fe3O4@RGO counter electrodes (low-cost indium- and platinum-free counter electrodes) is attributed to the interfacial compatibility between 2D graphene composite catalyst (Fe3O4@RGO) and 2D PET/GE conductive substrate. In addition, DSCs that use only PET/GE (without Fe3O4@RGO catalyst) as counter electrodes can also achieve a photocurrent density of 6.30 mA cm(-2). This work is beneficial for fundamental research and practical applications of graphene and graphene composite in photovoltaics, photocatalytic water splitting, supercapacitors. PMID:26838272

  14. 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.

  15. Composite electrode for storage batteries and the like

    SciTech Connect

    Faber, P.

    1980-09-16

    A metal/synthetic-resin composite electrode for a storage battery or the like is comprised of a perforate metal support which is flanked on both sides by openworks of polyolefin, e.g., partially fluorinated polyolefin, which are welded together within the openings of the support and carry the active material. The polyolefin openworks, together with the active material, are covered in turn with polyester fabric or polyester felt permeable fine porous cover layers.

  16. Synthesis of 2D/2D Structured Mesoporous Co3O4 Nanosheet/N-Doped Reduced Graphene Oxide Composites as a Highly Stable Negative Electrode for Lithium Battery Applications.

    PubMed

    Sennu, Palanichamy; Kim, Hyo Sang; An, Jae Youn; Aravindan, Vanchiappan; Lee, Yun-Sung

    2015-08-01

    Mesoporous Co3O4 nanosheets (Co3 O4 -NS) and nitrogen-doped reduced graphene oxide (N-rGO) are synthesized by a facile hydrothermal approach, and the N-rGO/Co3O4 -NS composite is formulated through an infiltration procedure. Eventually, the obtained composites are subjected to various characterization techniques, such as XRD, Raman spectroscopy, surface area analysis, X-ray photoelectron spectroscopy (XPS), and TEM. The lithium-storage properties of N-rGO/Co3O4 -NS composites are evaluated in a half-cell assembly to ascertain their suitability as a negative electrode for lithium-ion battery applications. The 2D/2D nanostructured mesoporous N-rGO/Co3O4 -NS composite delivered a reversible capacity of about 1305 and 1501 mAh g(-1) at a current density of 80 mA g(-1) for the 1st and 50th cycles, respectively. Furthermore, excellent cyclability, rate capability, and capacity retention characteristics are noted for the N-rGO/Co3O4 -NS composite. This improved performance is mainly related to the existence of mesoporosity and a sheet-like 2D hierarchical morphology, which translates into extra space for lithium storage and a reduced electron pathway. Also, the presence of N-rGO and carbon shells in Co3O4 -NS should not be excluded from such exceptional performance, which serves as a reliable conductive channel for electrons and act as synergistically to accommodate volume expansion upon redox reactions. Ex-situ TEM, impedance spectroscopy, and XPS, are also conducted to corroborate the significance of the 2D morphology towards sustained lithium storage.

  17. 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.

  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. 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

    2016-06-01

    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.

  20. Highly efficient flexible optoelectronic devices using metal nanowire-conducting polymer composite transparent electrode

    NASA Astrophysics Data System (ADS)

    Jung, Eui Dae; Nam, Yun Seok; Seo, Houn; Lee, Bo Ram; Yu, Jae Choul; Lee, Sang Yun; Kim, Ju-Young; Park, Jang-Ung; Song, Myoung Hoon

    2015-09-01

    Here, we report a comprehensive analysis of the electrical, optical, mechanical, and surface morphological properties of composite nanostrutures based on silver nanowires (AgNW) and PEDOT:PSS conducting polymer for the use as flexible and transparent electrodes. Compared to ITO or the single material of AgNW or PEDOT:PSS, the AgNW/PEDOT:PSS composite electrode showed high electrical conductivity with a low sheet resistance of 26.8 Ω/sq at 91% transmittance (at 550 nm), improves surface smoothness, and enhances mechanical properties assisted by an amphiphilic fluoro-surfactant. The polymeric light-emitting diodes (PLEDs) and organic solar cells (OSCs) using the AgNW/PEDOT:PSS composite electrode showed higher device performances than those with AgNW and PEDOT:PSS electrodes and excellent flexibility under bending test. These results indicates that the AgNW/PEDOT:PSS composite presented is a good candidate as next-generation transparent elelctrodes for applications into flexible optoelectronic devices. [Figure not available: see fulltext.

  1. 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.

  2. Carbon Film Electrodes For Super Capacitor Applications

    DOEpatents

    Tan, Ming X.

    1999-07-20

    A method for treating an organic polymer material, preferably a vinylidene chloride/vinyl chloride copolymer (Saran) to produce a flat sheet of carbon film material having a high surface area (.apprxeq.1000 m.sup.2 /g) suitable as an electrode material for super capacitor applications. The method comprises heating a vinylidene chloride/vinyl chloride copolymer film disposed between two spaced apart graphite or ceramic plates to a first temperature of about 160.degree. C. for about 14 hours to form a stabilized vinylidene chloride/vinyl chloride polymer film, thereafter heating the stabilized film to a second temperature of about 750.degree. C. in an inert atmosphere for about one hour to form a carbon film; and finally activating the carbon film to increase the surface area by heating the carbon film in an oxidizing atmosphere to a temperature of at least 750-850.degree. C. for between 1-6 hours.

  3. High performance nickel electrodes for space power applications

    NASA Technical Reports Server (NTRS)

    Adanuvor, Prosper K.; Pearson, Johnnie A.; Miller, Brian; Tatarchuk, Bruce; Britton, Doris L.

    1995-01-01

    The specific energy density and the performance of nickel electrodes are generally limited by the electrode microstructure and the nature of the active material within the electrode matrix. Progress is being made in our laboratory in a collaborative effort with NASA-LEWIS Research Center to develop lighter weight, mechanically stable and highly efficient nickel electrodes for aerospace applications. Our approach is based on an electrode microstructure fabricated from a mixture of nickel fibers as small as 2 micro m diameter and cellulose fibers. Results will be presented to show the optimum conditions for impregnating this electrode microstructure with nickel hydroxide active material. Performance data in half-cell tests and cycle life data will also be presented. The flexibility of this electrode microstructure and the significant advantages it offers in terms of weight and performance will be demonstrated, in particular its ability to accept charge at high rates and to discharge at high rates.

  4. High Performance Nickel Electrodes for Space Power Applications

    NASA Technical Reports Server (NTRS)

    Adanuvor, Prosper K.; Pearson, Johnnie A.; Miller, Brian; Tatarchuk, Bruce; Britton, Doris L.

    1996-01-01

    Performance characteristics such as efficiency, specific energy density and power density of nickel electrodes are generally limited by the electrode microstructure and nature of the active material within the electrode matrix. Progress is being made in our laboratory in a collaborative effort with NASA-Lewis Research Center to develop lighter weight, mechanically stable and highly efficient nickel electrodes for aerospace applications. Our approach is based on an electrode microstructure fabricated from a mixture of nickel fibers as small as 2 microns diameter and cellulose fibers. Performance data in flooded cell tests and cycle life data are presented. Performance characteristics are compared to other electrode microstructures such as the Fibrex Fiber mat and the Fibrex Powder substrate. The flexibility of our electrode microstructure and the significant advantages it offers in terms of weight and performance are demonstrated, in particular, its ability to accept charge at high rates and to discharge at high rates.

  5. 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

  6. Electrodeposited reduced-graphene oxide/cobalt oxide electrodes for charge storage applications

    NASA Astrophysics Data System (ADS)

    García-Gómez, A.; Eugénio, S.; Duarte, R. G.; Silva, T. M.; Carmezim, M. J.; Montemor, M. F.

    2016-09-01

    In the present work, electrochemically reduced-graphene oxide/cobalt oxide composites for charge storage electrodes were prepared by a one-step pulsed electrodeposition route on stainless steel current collectors and after that submitted to a thermal treatment at 200 °C. A detailed physico-chemical characterization was performed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Raman spectroscopy. The electrochemical response of the composite electrodes was studied by cyclic voltammetry and charge-discharge curves and related to the morphological and phase composition changes induced by the thermal treatment. The results revealed that the composites were promising materials for charge storage electrodes for application in redox supercapacitors, attaining specific capacitances around 430 F g-1 at 1 A g-1 and presenting long-term cycling stability.

  7. Oxygen exchange and transport in dual phase ceramic composite electrodes.

    PubMed

    Druce, John; Téllez, Helena; Ishihara, Tatsumi; Kilner, John A

    2015-01-01

    Composites consisting of a perovskite-based electronic or mixed conductor with a fluorite-structured ionic conductor are often used as electrodes in solid oxide electrochemical energy conversion devices. After sintering the materials, there is often evidence for inter-reaction between the two phases, or inter-diffusion of cations or impurities between the two phases. We studied the (18)O exchange properties of a composite consisting of CGO and LSCF in a 50 : 50 ratio. High resolution ToF-SIMS mapping reveals that the (18)O fraction at the very outer surface of grains of the CGO phase is much higher than expected from D* and k* values for the single-phase parent material. Surface compositional analysis by ToF-SIMS and low energy ion scattering (LEIS) spectroscopy suggests that the surfaces of the CGO grains in the composite do not show the impurities which typically segregate to the surface in single-phase CGO. Thus, the "cleaning" of impurities from the CGO surface by dissolution into the perovskite phase may be one explanation for the apparent enhanced surface exchange for CGO in these composites.

  8. Hybrid Electrodes of Carbon Nanotube and Reduced Graphene Oxide for Energy Storage Applications.

    PubMed

    Choi, Eunmi; Chae, Su Jin; Kim, Areum; Kang, Keun Won; Oh, Min Seok; Kwon, Soon Hyeong; Yoon, Sung Pil; Pyo, Sung Gyu

    2015-11-01

    The choice of electrode materials in lithium ion batteries and supercapacitors is important for the stability, capacity, and cycle life of the device. Despite its low capacity, graphite has often been used as an electrode material due to its inherent stability. Due to an increasing demand for large-capacity energy storage systems, there is also a demand for the development of large-capacity Li ion batteries and supercapacitors. Therefore, carbonaceous materials like graphene and carbon nanotubes (CNTs), which have high stability as well as excellent electrical conductivity and mechanical strength, are receiving attention as new electrode materials. Recently, starting from simply applying graphene and CNTs as electrode materials and progressing to the development of hybrid materials, there have been increasing research efforts in enhancing the performance of Li ion batteries and supercapacitors through the use of carbonaceous materials. This paper will discuss new composite materials and electrode structures that use graphene and CNTs for applications in Li ion batteries and supercapacitors.

  9. Polyaniline nanofiber/large mesoporous carbon composites as electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Liu, Huan; Xu, Bin; Jia, Mengqiu; Zhang, Mei; Cao, Bin; Zhao, Xiaonan; Wang, Yu

    2015-03-01

    A composite of polyaniline nanofiber/large mesoporous carbon (PANI-F/LMC) hybrid was prepared by an in situ chemical oxidative polymerization of aniline monomer with nano-CaCO3 templated LMC as host matrix for supercapacitors. The morphology, composition and electronic structure of the composites (PANI-F/LMC) together with pure PANI nanofibers and the LMC were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), FT-IR, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It is found that the PANI nanofibers were incorporated into the large mesochannels of LMC with interpenetrating framework formed. Such unique structure endows the PANI-F/LMC composite with a high capacitance of 473 F g-1 at a current load of 0.1 A g-1 with good rate performance and cycling stability, suggesting its potential application in the electrode material for supercapacitors.

  10. High-power supercapacitor electrodes from single-walled carbon nanohorn/nanotube composite.

    PubMed

    Izadi-Najafabadi, Ali; Yamada, Takeo; Futaba, Don N; Yudasaka, Masako; Takagi, Hideyuki; Hatori, Hiroaki; Iijima, Sumio; Hata, Kenji

    2011-02-22

    A novel composite is presented as a supercapacitor electrode with a high maximum power rating (990 kW/kg; 396 kW/l) exceeding power performances of other electrodes. The high-power capability of the electrode stemmed from its unique meso-macro pore structure engineered through the utilization of single-walled carbon nanotubes (20 wt %) as scaffolding for single-walled carbon nanohorns (80 wt %). The novel composite electrode also exhibited durable operation (6.5% decline in capacitance over 100 000 cycles) as a result of its monolithic chemical composition and mechanical stability. The novel composite electrode was benchmarked against another high-power electrode made from single-walled carbon nanotubes (Bucky paper electrode). While the composite electrode had a lower surface area compared to the Bucky paper electrode (280 vs 470 m(2)/g from nitrogen adsorption), it had a higher meso-macro pore volume (2.6 vs 1.6 mL/g from mercury porosimetry) which enabled the composite electrode to retain more electrolyte, ensuring facile ion transport, hence achieving a higher maximum power rating (970 vs 400 kW/kg). PMID:21210712

  11. Microfabricated Reference Electrodes and their Biosensing Applications

    PubMed Central

    Shinwari, M. Waleed; Zhitomirsky, David; Deen, Imran A.; Selvaganapathy, P. R.; Deen, M. Jamal; Landheer, D.

    2010-01-01

    Over the past two decades, there has been an increasing trend towards miniaturization of both biological and chemical sensors and their integration with miniaturized sample pre-processing and analysis systems. These miniaturized lab-on-chip devices have several functional advantages including low cost, their ability to analyze smaller samples, faster analysis time, suitability for automation, and increased reliability and repeatability. Electrical based sensing methods that transduce biological or chemical signals into the electrical domain are a dominant part of the lab-on-chip devices. A vital part of any electrochemical sensing system is the reference electrode, which is a probe that is capable of measuring the potential on the solution side of an electrochemical interface. Research on miniaturization of this crucial component and analysis of the parameters that affect its performance, stability and lifetime, is sparse. In this paper, we present the basic electrochemistry and thermodynamics of these reference electrodes and illustrate the uses of reference electrodes in electrochemical and biological measurements. Different electrochemical systems that are used as reference electrodes will be presented, and an overview of some contemporary advances in electrode miniaturization and their performance will be provided. PMID:22294894

  12. Graphene Oxide/ Ruthenium Oxide Composites for Supercapacitors Electrodes

    NASA Astrophysics Data System (ADS)

    Amir, Fatima

    Supercapacitors are electrical energy storage devices with high power density, high rate capability, low maintenance cost, and long life cycle. They complement or replace batteries in harvesting applications when high power delivery is needed. An important improvement in performance of supercapacitors has been achieved through recent advances in the development of new nanostructured materials. Here we will discuss the fabrication of graphene oxide/ ruthenium oxide supercacitors electrodes including electrophoretic deposition. The morphology and structure of the fabricated electrodes were investigated and will be discussed. The electrochemical properties were determined using cyclic voltammetry and galvanostatic charge/discharge techniques and the experiments that demonstrate the excellent capacitive properties of the obtained supercapacitors will also be discussed. The fabrication and characterization of the samples were performed at the Center of Functional Nanomaterials at Brookhaven National Lab. The developed approaches in our study represent an exciting direction for designing the next generation of energy storage devices. This work was supported in part by the U.S. Department of Energy through the Visiting Faculty Program and the research used resources of the Center for Functional Nanomaterials at Brookhaven National Laboratory.

  13. Sulphured Polyacrylonitrile Composite Analysed by in operando UV-Visible Spectroscopy and 4-electrode Swagelok Cell.

    PubMed

    Dominko, Robert; Patel, Manu U M; Bele, Marjan; Pejovnik, Stane

    2016-01-01

    The electrochemical characteristics of sulfurized polyacrylonitrile composite (PAN/S) cathodes were compared with the commonly used carbon/S-based composite material. The difference in the working mechanism of these composites was examined. Analytical investigations were performed on both kinds of cathode electrode composites by using two reliable analytical techniques, in-situ UV-Visible spectroscopy and a four-electrode Swagelok cell. This study differentiates the working mechanisms of PAN/S composites from conventional elemental sulphur/carbon composite and also sheds light on factors that could be responsible for capacity fading in the case of PAN/S composites. PMID:27640383

  14. High energy density asymmetric supercapacitor based on NiOOH/Ni3S2/3D graphene and Fe3O4/graphene composite electrodes.

    PubMed

    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 Fe(3)O(4) nanoparticles and chemically reduced graphene oxide (Fe(3)O(4)/rGO) is synthesized as the anode material. The Fe(3)O(4)/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.

  15. Carbon film electrodes for super capacitor applications

    SciTech Connect

    Tan, M.X.

    1999-11-30

    A microporous carbon film for use as electrodes in energy storage devices is disclosed, which is made by the process comprising the steps of: (1) heating a polymer film material consisting essentially of a copolymer of polyvinylidene chloride and polyvinyl chloride in an inert atmosphere to form a carbon film; and (2) activating said carbon film to form said microporous carbon film having a density between about 0.7 g/cm{sup 2} and 1 g/cm{sup 2} and a gravimetric capacitance of about between 120 F/g and 315 F/g.

  16. Carbon film electrodes for super capacitor applications

    DOEpatents

    Tan, Ming X.

    1999-01-01

    A microporous carbon film for use as electrodes in energy strorage devices is disclosed, which is made by the process comprising the steps of: (1) heating a polymer film material consisting essentially of a copolymer of polyvinylidene chloride and polyvinyl chloride in an inert atmosphere to form a carbon film; and (2) activating said carbon film to form said microporous carbon film having a density between about 0.7 g/cm.sup.2 and 1 g/cm.sup.2 and a gravimetric capacitance of about between 120 F/g and 315 F/g.

  17. Coated-Wire Ion Selective Electrodes and Their Application to the Teaching Laboratory.

    ERIC Educational Resources Information Center

    Martin, Charles R.; Freiser, Henry

    1980-01-01

    Describes the procedures for construction of a nitrate coated-wire ion selective electrode and suggests experiments for evaluation of electrode response and illustration of typical analytical applications of ion selective electrodes. (CS)

  18. 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.

  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. Capacitance behavior of nanostructured ɛ-MnO2/C composite electrode using different carbons matrix

    NASA Astrophysics Data System (ADS)

    Tran, Van Man; Ha, An The; Loan Phung Le, My

    2014-06-01

    In this work nanostructured ɛ-MnO2/C composite electrode was synthesized via the reduction reaction of potassium permanganate. A wide range of carbons such as mesoporous carbon (MC), graphite (GC), super P carbon (super P) and Vulcan carbon (VC) were used in order to enhance the interfacial electrical conductivity and the electrochemical capacitance of the composite electrodes. Physical properties, structure and specific surface area of electrode materials were investigated by scanning electron microscopy (SEM), x-ray diffraction and nitrogen adsorption measurements. The capacitance behavior of MnO2/C materials was studied in aqueous and non-aqueous solution using cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy measurements. The composite electrode exhibits the highest capacitance at 30 wt% activated carbon. Among different carbons used, the maximum capacitance of MnO2/super P electrode is as high as 205 F g-1 at 50 mV s-1 and retains 98% after 300 cycles.

  1. Method of making a layered composite electrode/electrolyte

    DOEpatents

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

    2005-01-25

    An electrode/electrolyte structure is prepared by a plurality of methods. An unsintered (possibly bisque fired) moderately catalytic electronically-conductive or homogeneous mixed ionic electronic conductive electrode material is deposited on a layer composed of a sintered or unsintered ionically-conductive electrolyte material prior to being sintered. A layer of particulate electrode material is deposited on an unsintered ("green") layer of electrolyte material and the electrode and electrolyte layers are sintered simultaneously, sometimes referred to as "co-firing," under conditions suitable to fully densify the electrolyte while the electrode retains porosity. Or, the layer of particulate electrode material is deposited on a previously sintered layer of electrolyte, and then sintered. Subsequently, a catalytic material is added to the electrode structure by infiltration of an electrolcatalyst precursor (e.g., a metal salt such as a transition metal nitrate). This may be followed by low temperature firing to convert the precursor to catalyst. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in an ionic (electrochemical) device such as fuel cells and electrolytic gas separation systems.

  2. Potential applications of a small high-surface-area platinum electrode as an implanted impedance biosensor or recording electrode

    NASA Astrophysics Data System (ADS)

    Duan, Yvonne Y.; Millard, Rodney E.; Tykocinski, Michael; Lui, Xuguang; Clark, Graeme M.; Cowan, Robert S. C.

    2001-03-01

    A small Platinum (Pt) electrode (geometric area: ~0.43 mm2) was treated in an electrochemical etching process, to produce a highly porous columnar thin layer (~600 nm) on the surface of the electrode. The modified Pt electrode (Pt-p) showed similar electrical properties to a platinum-black electrode but with high mechanical integrity. Previous studies of chronic stimulation had also shown good biocompatibility and surface stability over several months implantation. This paper discusses the potential applications of the modified electrode as an implanted bio-sensor: (1) as a recording electrode compared to an untreated Pt electrode. (2) as a probe in detecting electrical characteristics of living biological material adjacent to the electrode in vivo, which may correlate to inflammation or trauma repair. Results of electrochemical impedance spectroscopy (EIS) revealed much lower electrode interface polarisation impedance, reduced overall electrode impedance, and a largely constant impedance above 100 Hz for the Pt-p electrode compared with untreated Pt electrodes. This provides a platform for recording biological events with low noise interference. Results of A.C. impedance spectroscopy of the high surface area electrode only reflect changes in the surrounding biological environment in the frequency range (1 k Hz to 100 k Hz), interference from electrode polarisation impedance can be neglected. The results imply that the surface-modified electrode is a good candidate for application to implantable biosensors for detecting bio-electric events. The modification procedure and its high surface area concept could have application to a smart MEMS device or microelectrode.

  3. 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. PMID:27398829

  4. 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.

  5. A New Tiapride Selective Electrode and Its Clinical Application

    PubMed Central

    Ortuño, Joaquín A.; Ródenas, Vicente; García, Mª Soledad; Albero, Mª Isabel; Sánchez-Pedreño, Concepción

    2007-01-01

    The construction and electrochemical response characteristics of a poly(vinyl chloride) (PVC) membrane selective electrode for the determination of tiapride (TPD) are described. The sensing membrane comprised an ion-pair formed between the protonated drug and tetraphenylborate (TPB-) in a plasticized PVC matrix. The influence of membrane composition on the electrode response was studied. The electrode showed a fast, stable and Nernstian response over a wide tiapride concentration range (1x10-5-1x10-2 M) with a slope of 57.5±0.2 mV dec-1 of concentration, a detection limit of 4.3x10-6±2.5x10-7 M, a wide working pH range (2-8) and a fast response time (< 5 s). The electrode showed good selectivity towards tiapride with respect to some inorganic and organic compounds. The electrode has been applied to the determination of tiapride in human urine and iontophoresis solution.

  6. New composite electrodes made of polypyrrole and graphite: Construction, optimization and characterization

    NASA Astrophysics Data System (ADS)

    Dione, G.; Dieng, M. M.; Aaron, J. J.; Cachet, H.; Cachet, C.

    In this work, new composite electrodes were developed, optimized and characterized for possible, future use in batteries and/or super-capacitors. These composite electrodes were prepared from chemically synthesized polypyrrole (Ppy), graphite carbon and Teflon and their physico-chemical performances were tested using different techniques. Their conductivity and porosity were investigated under various conditions. Their macroporous structure was also studied by the BET method. Two distinct electrochemical reactions were found to take place at these electrodes, including a redox reaction with insertion and expulsion of anions, and a capacitive reaction at the electrode/electrolyte interface. The specific capacity, experimentally obtained with an electrode containing 40 wt% of Ppy (99.6 mAh g -1), was larger than the theoretical one, due to double-layer effects at the Ppy/electrolyte interface. The double-layer capacitance at the electrode/electrolyte interface of the composite electrodes, investigated by electrochemical impedance spectroscopy, was found to represent at most 0.1% of the total electrode capacitance.

  7. 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. PMID:27523568

  8. 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.

  9. Clinical experience in the application of the tissue pH electrode.

    PubMed

    Lichtenegger, W; Burghardt, E

    1978-09-01

    Only after placing the pH electrode through an incision could its point enter deep enough into the tissue. The storage of the pH electrode in a reference buffer considerably improved the stability of the electrode. The ECG electrode is at present the weakest link in the realization of continuous pH measurements. Improvements should be effected mainly with the ECG electrode, the electrode cable and the application instruments.

  10. 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.

  11. 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

  12. 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.

  13. 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).

  14. Ferrocene-functionalized graphene electrode for biosensing applications.

    PubMed

    Rabti, Amal; Mayorga-Martinez, Carmen C; Baptista-Pires, Luis; Raouafi, Noureddine; Merkoçi, Arben

    2016-07-01

    A novel ferrocene-functionalized reduced graphene oxide (rGO)-based electrode is proposed. It was fabricated by the drop casting of ferrocene-functionalized graphene onto polyester substrate as the working electrode integrated within screen-printed reference and counter electrodes. The ferrocene-functionalized rGO has been fully characterized using FTIR, XPS, contact angle measurements, SEM and TEM microscopy, and cyclic voltammetry. The XPS and EDX analysis showed the presence of Fe element related to the introduced ferrocene groups, which is confirmed by a clear CV signal at ca. 0.25 V vs. Ag/AgCl (0.1 KCl). Mediated redox catalysis of H2O2 and bio-functionalization with glucose oxidase for glucose detection were achieved by the bioelectrode providing a proof for potential biosensing applications. PMID:27216390

  15. Ferrocene-functionalized graphene electrode for biosensing applications.

    PubMed

    Rabti, Amal; Mayorga-Martinez, Carmen C; Baptista-Pires, Luis; Raouafi, Noureddine; Merkoçi, Arben

    2016-07-01

    A novel ferrocene-functionalized reduced graphene oxide (rGO)-based electrode is proposed. It was fabricated by the drop casting of ferrocene-functionalized graphene onto polyester substrate as the working electrode integrated within screen-printed reference and counter electrodes. The ferrocene-functionalized rGO has been fully characterized using FTIR, XPS, contact angle measurements, SEM and TEM microscopy, and cyclic voltammetry. The XPS and EDX analysis showed the presence of Fe element related to the introduced ferrocene groups, which is confirmed by a clear CV signal at ca. 0.25 V vs. Ag/AgCl (0.1 KCl). Mediated redox catalysis of H2O2 and bio-functionalization with glucose oxidase for glucose detection were achieved by the bioelectrode providing a proof for potential biosensing applications.

  16. Quartz crystal impedance response of nonhomogenous composite electrodes in contact with liquids.

    PubMed

    Daikhin, Leonid; Sigalov, Sergey; Levi, Mikhael D; Salitra, Gregory; Aurbach, Doron

    2011-12-15

    A new model of quartz-crystal impedance (QCI) of nonuniform layers composed of bumps of carbon particles (either porous or nonporous) and a polymeric binder layer has been proposed. The solid particles are modeled by semispherical and oblate semispheroid bumps embedded into the "sea" of a polymeric binder layer. On the basis of this model and elaborating on the principles of hydrodynamic spectroscopy of composite electrode materials, the geometric and porous structure parameters of nanoporous carbon and nonporous graphite composite electrodes in contact with liquids have been reliably determined. This work is believed to create a solid theoretical background for both advanced studies and optimized formulations of the composite electrodes suited to practical electrochemical devices and for the interpretation of the processes of ions and solvent insertion into nanoporous carbon electrodes uniquely probed by the QCI method (supercapacitive cells, desalination membranes).

  17. 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.

  18. Active C4 Electrodes for Local Field Potential Recording Applications

    PubMed Central

    Wang, Lu; Freedman, David; Sahin, Mesut; Ünlü, M. Selim; Knepper, Ronald

    2016-01-01

    Extracellular neural recording, with multi-electrode arrays (MEAs), is a powerful method used to study neural function at the network level. However, in a high density array, it can be costly and time consuming to integrate the active circuit with the expensive electrodes. In this paper, we present a 4 mm × 4 mm neural recording integrated circuit (IC) chip, utilizing IBM C4 bumps as recording electrodes, which enable a seamless active chip and electrode integration. The IC chip was designed and fabricated in a 0.13 μm BiCMOS process for both in vitro and in vivo applications. It has an input-referred noise of 4.6 μVrms for the bandwidth of 10 Hz to 10 kHz and a power dissipation of 11.25 mW at 2.5 V, or 43.9 μW per input channel. This prototype is scalable for implementing larger number and higher density electrode arrays. To validate the functionality of the chip, electrical testing results and acute in vivo recordings from a rat barrel cortex are presented. PMID:26861324

  19. Active C4 Electrodes for Local Field Potential Recording Applications.

    PubMed

    Wang, Lu; Freedman, David; Sahin, Mesut; Ünlü, M Selim; Knepper, Ronald

    2016-02-04

    Extracellular neural recording, with multi-electrode arrays (MEAs), is a powerful method used to study neural function at the network level. However, in a high density array, it can be costly and time consuming to integrate the active circuit with the expensive electrodes. In this paper, we present a 4 mm × 4 mm neural recording integrated circuit (IC) chip, utilizing IBM C4 bumps as recording electrodes, which enable a seamless active chip and electrode integration. The IC chip was designed and fabricated in a 0.13 μm BiCMOS process for both in vitro and in vivo applications. It has an input-referred noise of 4.6 μV rms for the bandwidth of 10 Hz to 10 kHz and a power dissipation of 11.25 mW at 2.5 V, or 43.9 μW per input channel. This prototype is scalable for implementing larger number and higher density electrode arrays. To validate the functionality of the chip, electrical testing results and acute in vivo recordings from a rat barrel cortex are presented.

  20. 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. PMID:27332854

  1. 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.

  2. 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. PMID:27510029

  3. 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.

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

    PubMed

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

    2010-09-01

    A novel concept is proposed for the encapsulation of components within polyacrylate microspheres, prior to their incorporation into a membrane phase. Thus finer and better controlled dispersion of heterogeneous membrane components can be achieved. This concept was verified by using a poly(n-butyl acrylate) membrane-based reference electrode as an example. In this example the proper dispersion of solid constituents of the heterogeneous membrane and prevention of their leakage are both of primary importance. Potassium chloride-loaded poly(n-butyl acrylate) microspheres were prepared and then left in contact with silver nitrate to convert some of the KCl into AgCl. The material obtained was introduced into a poly(n-butyl acrylate) membrane. The reference electrode membranes obtained in this way were characterized with much more stable potential (both in different electrolytes and over time) compared with electrodes prepared by the direct introduction of KCl and AgCl to the membrane. PMID:20652191

  5. Composite electrode composed of bimodal porous carbon and polypyrrole for electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Woo, Sang-Wook; Dokko, Kaoru; Kanamura, Kiyoshi

    Three-dimensionally ordered macroporous (3DOM) carbons having walls composed of mesosized spherical pores were prepared by a colloidal crystal templating method. A composite electrode consisting of bimodal porous carbon and polypyrrole (PPy) was prepared by electropolymerization of pyrrole within the macropores of the bimodal porous carbon. The porous structure of the composite electrode was analyzed using a scanning electron microscope and by nitrogen adsorption-desorption measurement. It was found that the deposition of PPy decreased the porosity and specific surface area of the electrode. The electrochemical properties of the composite electrode were characterized in a mixed solution of ethylene carbonate and diethyl carbonate containing 1 mol dm -3 LiPF 6. The discharge capacity of the carbon-PPy composite electrode was 78 mAh g carbon-PPy -1 in the potential range of 2.0-4.0 V vs. Li/Li +, which corresponded to a volumetric discharge capacity of 53 mAh cm -3. Both the double-layer capacity (31 mAh g -1) and the redox capacity of PPy (47 mAh g -1) contributed to the discharge capacity of the composite electrode. This indicates that the incorporation of PPy into the macropores of bimodal porous carbon is effective in increasing the volumetric discharge capacity of the composite electrode. The composite of carbon and PPy showed good rate capability, and its discharge capacity at a high current density of 4.0 A g -1 was as high as 49 mAh g -1.

  6. A novel electrode-bipolar plate assembly for vanadium redox flow battery applications

    NASA Astrophysics Data System (ADS)

    Qian, Peng; Zhang, Huamin; Chen, Jian; Wen, Yuehua; Luo, Qingtao; Liu, Zonghao; You, Dongjiang; Yi, Baolian

    A novel electrode-bipolar plate assembly has been developed and evaluated for application in the vanadium redox flow battery (VRB). It is composed of three parts: a graphite felt (electrode), an adhesive conducting layer (ACL) and a flexible graphite plate (bipolar plate). The ACL connects the electrode with the bipolar plate to an assembly. By the evaluations of cost, resistivity, surface morphology, electrolyte permeation and single cell performance, this novel assembly demonstrates its applicability in VRB as evident in the following outcomes: (1) lowers the cost and area resistivity to about 10% and 40% of the conventional setups, respectively; (2) improves electrical conductivity to 4.97 mΩ cm as compared to over 100 mΩ cm of the carbon-plastic composite bipolar plate; (3) attains zero electrolyte permeation; and (4) achieves a higher energy efficiency of 81% at a charge/discharge current density of 40 mA cm -2 when employed in a VRB single cell, which is 73% for the conventional setup. All these indicate that the novel electrode-bipolar plate assembly is a promising candidate for VRB applications.

  7. Graphene-MoS2 nanosheet composites as electrodes for dye sensitised solar cells

    NASA Astrophysics Data System (ADS)

    Lynch, Peter; Khan, Umar; Harvey, Andrew; Ahmed, Iftikhar; Coleman, Jonathan N.

    2016-03-01

    Replacing the platinum counter electrode in dye-senstized solar cells with a cheaper material has attracted much attention recently. Graphene, graphene oxide and other 2-dimensional materials have received significant attention. Here we demonstrate the dependence of device parameters on the thickness of counter electrodes formed from porous, disordered arrays of liquid-exfoliated graphene nanosheets. We find device efficiency to saturate at a counter electrode thickness of ∼400 nm. Such optimised counter electrodes can be improved further by adding MoS2 nanosheets to the graphene electrode. By measuring the dependence of device parameters on the composition of mixed graphene/MoS2 electrodes, we show that adding ∼10 wt% MoS2 nanosheets to a graphene counter electrode improves performance and can result in a cell efficiency of ∼95% of that achieved using a platinum electrode. This data is consistent with the MoS2 nanosheets being somewhat better catalysts than the graphene nanosheets. However, the graphene nanosheets are required to render the electrode conductive. More detailed analysis suggests the better performance of the MoS2 nanosheets to be mostly down to their smaller size.

  8. 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.

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

    SciTech Connect

    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.

  11. Characterization of nanoporous gold electrodes for bioelectrochemical applications.

    PubMed

    Scanlon, Micheál D; Salaj-Kosla, Urszula; Belochapkine, Serguei; MacAodha, Domhnall; Leech, Dónal; Ding, Yi; Magner, Edmond

    2012-01-31

    The high surface areas of nanostructured electrodes can provide for significantly enhanced surface loadings of electroactive materials. The fabrication and characterization of nanoporous gold (np-Au) substrates as electrodes for bioelectrochemical applications is described. Robust np-Au electrodes were prepared by sputtering a gold-silver alloy onto a glass support and subsequent dealloying of the silver component. Alloy layers were prepared with either a uniform or nonuniform distribution of silver and, post dealloying, showed clear differences in morphology on characterization with scanning electron microscopy. Redox reactions under kinetic control, in particular measurement of the charge required to strip a gold oxide layer, provided the most accurate measurements of the total electrochemically addressable electrode surface area, A(real). Values of A(real) up to 28 times that of the geometric electrode surface area, A(geo), were obtained. For diffusion-controlled reactions, overlapping diffusion zones between adjacent nanopores established limiting semi-infinite linear diffusion fields where the maximum current density was dependent on A(geo). The importance of measuring the surface area available for the immobilization was determined using the redox protein, cyt c. The area accessible to modification by a biological macromolecule, A(macro), such as cyt c was reduced by up to 40% compared to A(real), demonstrating that the confines of some nanopores were inaccessible to large macromolecules due to steric hindrances. Preliminary studies on the preparation of np-Au electrodes modified with osmium redox polymer hydrogels and Myrothecium verrucaria bilirubin oxidase (MvBOD) as a biocathode were performed; current densities of 500 μA cm(-2) were obtained in unstirred solutions. PMID:22004670

  12. 21 CFR 884.2685 - Fetal scalp clip electrode and applicator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Fetal scalp clip electrode and applicator. 884... Monitoring Devices § 884.2685 Fetal scalp clip electrode and applicator. (a) Identification. A fetal scalp clip electrode and applicator is a device designed to establish electrical contact between fetal...

  13. 21 CFR 884.2685 - Fetal scalp clip electrode and applicator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Fetal scalp clip electrode and applicator. 884... Monitoring Devices § 884.2685 Fetal scalp clip electrode and applicator. (a) Identification. A fetal scalp clip electrode and applicator is a device designed to establish electrical contact between fetal...

  14. 21 CFR 884.2685 - Fetal scalp clip electrode and applicator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Fetal scalp clip electrode and applicator. 884... Monitoring Devices § 884.2685 Fetal scalp clip electrode and applicator. (a) Identification. A fetal scalp clip electrode and applicator is a device designed to establish electrical contact between fetal...

  15. 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

    ordered structure of the VACNTs showed superior performance compared to randomly oriented CNTs. To increase the energy density, the second approach was taken, by combining pre-synthesized conducting polymers (CPs) and carbon nanotubes (CNTs) using a facile scalable dispersion filtration method to produce free-standing electrodes. Composites with the three main CPs were prepared, analyzed in various electrolytes, and their performance was comparable with polymer/ CNT films prepared with more complex techniques such as in-situ polymerization and pellet pressing. Then, based on the idea that the quinone molecules present in lignin store charge by undergoing a 2 proton, 2 electron redox reaction, a composite between polypyrrole, a stable conducting polymer, and the prototypical molecule p-benzoquinone was fabricated by electropolymerization of pyrrole in the presence of the redox molecule. A significant increase in capacitance and capacity was obtained with respect to polypyrrole films. Furthermore, an important obstacle in the application of CPs in SCs is the lack of easily reduced (n-dopable) polymers. Poly(aminoanthraquinone) (PAQ) is a conjugated polymer that shows electroactivity in the negative potential range of 0 to -2 V, due to the redox moieties of the polymer. PAQ was electropolymerized on free-standing CNT films and its performance as anode for SCs was studied. The materials and processing techniques described in this dissertation are useful to further develop high power/high energy electrodes for SCs.

  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

    2016-08-01

    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.

  18. 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.

  19. 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

    2016-08-01

    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. PMID:27324723

  20. Electroanalytical applications of screen-printable surfactant-induced sol-gel graphite composites

    DOEpatents

    Guadalupe, Ana R.; Guo, Yizhu

    2001-05-15

    A process for preparing sol-gel graphite composite electrodes is presented. This process preferably uses the surfactant bis(2-ethylhexyl) sulfosuccinate (AOT) and eliminates the need for a cosolvent, an acidic catalyst, a cellulose binder and a thermal curing step from prior art processes. Fabrication of screen-printed electrodes by this process provides a simple approach for electroanalytical applications in aqueous and nonaqueous solvents. Examples of applications for such composite electrodes produced from this process include biochemical sensors such as disposable, single-use glucose sensors and ligand modified composite sensors for metal ion sensitive sensors.

  1. Graphene-epoxy composite electrode fabricated by in situ polycondensation for enhanced amperometric detection in capillary electrophoresis.

    PubMed

    Tang, Dengfeng; Ma, Guo; Zhang, Luyan; Chen, Gang

    2013-11-01

    This report describes the development and application of a novel graphene-epoxy composite electrode as a sensitive amperometric detector of capillary electrophoresis. The composite electrode was fabricated on the basis of the in situ polycondensation of a mixture of graphene and 1,2-ethanediamine-containing bisphenol A epoxy resin in the inner bore of a piece of fused silica capillary under heat. The structure of the material was investigated by scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and Fourier transform infrared spectroscopy. The results indicated that graphene sheets were well dispersed and interconnected throughout the composite to form an electrically conductive network. The performance of this unique electrode was demonstrated by separating and detecting two naturally occurring phenolic compounds in rosemary in combination with capillary electrophoresis. The graphene-based detector offered significantly lower operating potentials, higher sensitivity, satisfactory resistance to surface fouling, and lower expense of operation, indicating great promise for a wide range of applications. PMID:24119752

  2. 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.

  3. Critical roles of binders and formulation at multiscales of silicon-based composite electrodes

    NASA Astrophysics Data System (ADS)

    Mazouzi, D.; Karkar, Z.; Reale Hernandez, C.; Jimenez Manero, P.; Guyomard, D.; Roué, L.; Lestriez, B.

    2015-04-01

    In this review we try to shed a comprehensive understanding on the influence of the different parameters of the formulation of silicon-based composite electrode on its cyclability, i.e. the binder, the conductive additives, the current collector, the electrode porosity and solid loading, in view of a more rational assessment of the relevancy of these parameters for the battery technology. The reasons of the better efficiency of carboxymethyl cellulose and alternative new binders than PVdF are first addressed into details. The critical effects of the active mass loading and porosity on the cyclability are highlighted. Then the influence of the conductive additive type and current collector texture are discussed. Putting everything together shows that it is required to meticulously optimize all the different scales of the composite electrode to hopefully raise the performance of silicon-based electrode above that of graphite commercial ones.

  4. Composite structural materials. [aircraft applications

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1981-01-01

    The development of composite materials for aircraft applications is addressed with specific consideration of physical properties, structural concepts and analysis, manufacturing, reliability, and life prediction. The design and flight testing of composite ultralight gliders is documented. Advances in computer aided design and methods for nondestructive testing are also discussed.

  5. Dispersion of Nanocrystalline Fe3O4 within Composite Electrodes: Insights on Battery-Related Electrochemistry.

    PubMed

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

    2016-05-11

    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. This study provides insight into the specific effects of aggregation on electrochemistry through a multiscale view of mechanisms for magnetite composite electrodes. PMID:27096464

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

    DOE PAGES

    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.; et al

    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

  7. A reduced graphene oxide/Co{sub 3}O{sub 4} composite for supercapacitor electrode

    SciTech Connect

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

    2013-03-15

    20 nm sized Co{sub 3}O{sub 4} nanoparticles are in-situ grown on the chemically reduced graphene oxide (rGO) sheets to form a rGO-Co{sub 3}O{sub 4} composite during hydrothermal processing. The rGO-Co{sub 3}O{sub 4} composite is employed as the pseudocapacitor electrode in the 2 M KOH aqueous electrolyte solution. The rGOCo{sub 3}O{sub 4} 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 rGOCo{sub 3}O{sub 4} 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 Co{sub 3}O{sub 4} particles combined with high electronic conductivity of the rGO sheets.

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

    NASA Astrophysics Data System (ADS)

    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 rGO-Co3O4 composite electrode exhibits a specific capacitance of 472 F g-1 at a scan rate of 2 mV s-1 in a two-electrode cell. 82.6% of capacitance is retained when the scan rate increases to 100 mV s-1. The rGO-Co3O4 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-1 at a power density of 8.3 kW kg-1. 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.

  9. Biosensing applications of titanium dioxide coated graphene modified disposable electrodes.

    PubMed

    Kuralay, Filiz; Tunç, Selma; Bozduman, Ferhat; Oksuz, Lutfi; Oksuz, Aysegul Uygun

    2016-11-01

    In the present work, preparation of titanium dioxide coated graphene (TiO2/graphene) and the use of this nanocomposite modified electrode for electrochemical biosensing applications were detailed. The nanocomposite was prepared with radio frequency (rf) rotating plasma method which serves homogeneous distribution of TiO2 onto graphene. TiO2/graphene was characterized with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis. Then, this nanocomposite was dissolved in phosphate buffer solution (pH 7.4) and modified onto disposable pencil graphite electrode (PGE) by dip coating for the investigation of the biosensing properties of the prepared electrode. TiO2/graphene modified PGE was characterized with SEM, EDS and cyclic voltammetry (CV). The sensor properties of the obtained surface were examined for DNA and DNA-drug interaction. The detection limit was calculated as 1.25mgL(-1) (n=3) for double-stranded DNA (dsDNA). RSD% was calculated as 2.4% for three successive determinations at 5mgL(-1) dsDNA concentration. Enhanced results were obtained compared to the ones obtained with graphene and unmodified (bare) electrodes. PMID:27591620

  10. [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.

  11. 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%)

  12. Fabrication of β-cyclodextrin-coated poly (diallyldimethylammonium chloride)-functionalized graphene composite film modified glassy carbon-rotating disk electrode and its application for simultaneous electrochemical determination colorants of sunset yellow and tartrazine.

    PubMed

    Ye, Xiaoliang; Du, Yongling; Lu, Daban; Wang, Chunming

    2013-05-24

    We proposed a green and facile approach for the synthesis of β-cyclodextrin-coated poly(diallyldimethylammonium chloride)-functionalized graphene composite film (β-CD-PDDA-Gr) by using L-ascorbic acid (L-AA) as the reducing agent at room temperature. The β-CD-PDDA-Gr composite film modified glassy carbon-rotating disk electrode (GC-RDE) was then developed for the sensitive simultaneous determination of two synthetic food colorants: sunset yellow (SY) and tartrazine (TT). By cyclic voltammetry (CV), the peak currents of SY and TT increased obviously on the developed electrochemical sensor. The kinetic parameters, such as diffusion coefficient D and standard heterogeneous rate constant kb, were estimated by linear sweep voltammetry (LSV). Under the optimal conditions, the differential pulse voltammetry (DPV) signals of SY and TT on the β-CD-PDDA-Gr modified GC-RDE were significantly enhanced. The enhanced anodic peak currents represented the excellent analytical performance of simultaneous detection of SY and TT in the range of 5.0×10(-8) to 2.0×10(-5) mol L(-1), with a low limit of detection (LOD) of 1.25×10(-8) mol L(-1) for SY and 1.43×10(-8) mol L(-1) for TT (SN(-1)=3). This proposed method displayed outstanding selectivity, good stability and acceptable repeatability and reproducibility, and also has been used to simultaneously determine SY and TT in some commercial soft drinks with satisfactory results. The obtained results were compared to HPLC of analysis for those two colorants and no significant differences were found. By the treatment of the experimental data, the electrochemical reaction mechanisms of SY and TT both involved a one-electron-one-proton-transfer process. PMID:23663668

  13. 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

  14. Electrochemical studies on nanometal oxide-activated carbon composite electrodes for aqueous supercapacitors

    NASA Astrophysics Data System (ADS)

    Ho, Mui Yen; Khiew, Poi Sim; Isa, Dino; Chiu, Wee Siong

    2014-11-01

    In present study, the electrochemical performance of eco-friendly and cost-effective titanium oxide (TiO2)-based and zinc oxide-based nanocomposite electrodes were studied in neutral aqueous Na2SO3 electrolyte, respectively. The electrochemical properties of these composite electrodes were studied using cyclic voltammetry (CV), galvanostatic charge-discharge (CD) and electrochemical impedance spectroscopy (EIS). The experimental results reveal that these two nanocomposite electrodes achieve the highest specific capacitance at fairly low oxide loading onto activated carbon (AC) electrodes, respectively. Considerable enhancement of the electrochemical properties of TiO2/AC and ZnO/AC nanocomposite electrodes is achieved via synergistic effects contributed from the nanostructured metal oxides and the high surface area mesoporous AC. Cations and anions from metal oxides and aqueous electrolyte such as Ti4+, Zn2+, Na+ and SO32- can occupy some pores within the high-surface-area AC electrodes, forming the electric double layer at the electrode-electrolyte interface. Additionally, both TiO2 and ZnO nanoparticles can provide favourable surface adsorption sites for SO32- anions which subsequently facilitate the faradaic processes for pseudocapacitive effect. These two systems provide the low cost material electrodes and the low environmental impact electrolyte which offer the increased charge storage without compromising charge storage kinetics.

  15. Conducting polymer/graphite fiber composites for high charge density battery electrodes

    SciTech Connect

    Coffey, B.; Madsen, P.V.; Poehler, T.O.; Searson, P.C.

    1994-12-31

    A porous graphite fiber matrix (Toray Graphite Paper) provides a practical substrate into which electropolymerization of conducting Polymers, such as Polypyrrole, may be carried out to form composite, porous electrode structures. The graphite matrix provides a lightweight, intrinsically conducting structure with high surface area. The resultant porous electrode structures offer possibilities for enhanced charge capacity and current availability characteristics over dense films produced on planar substrates. Polypyrrole/graphite composites prepared by anodic electropolymerization are characterized for their charge capacity and overall morphology as a function of polymerization time. Reversible charge capacities in excess of 4.0 C/cm{sup 2} or 70 mAh/g have been obtained for these polypyrrole/graphite composite electrodes. Charge release for thick films is slow due to mass transport limitations.

  16. Polyaniline modified graphene and carbon nanotube composite electrode for asymmetric supercapacitors of high energy density

    NASA Astrophysics Data System (ADS)

    Cheng, Qian; Tang, Jie; Shinya, Norio; Qin, Lu-Chang

    2013-11-01

    Graphene and single-walled carbon nanotube (CNT) composites are explored as the electrodes for supercapacitors by coating polyaniline (PANI) nano-cones onto the graphene/CNT composite to obtain graphene/CNT-PANI composite electrode. The graphene/CNT-PANI electrode is assembled with a graphene/CNT electrode into an asymmetric pseudocapacitor and a highest energy density of 188 Wh kg-1 and maximum power density of 200 kW kg-1 are achieved. The structure and morphology of the graphene/CNT composite and the PANI nano-cone coatings are characterized by both scanning electron microscopy and transmission electron microscopy. The excellent performance of the assembled supercapacitors is also discussed and it is attributed to (i) effective utilization of the large surface area of the three-dimensional network structure of graphene-based composite, (ii) the presence of CNT in the composite preventing graphene from re-stacking, and (ii) uniform and vertically aligned PANI coating on graphene offering increased electrical conductivity.

  17. Electrocatalytic Hydrogen Evolution from Molybdenum Sulfide-Polymer Composite Films on Carbon Electrodes.

    PubMed

    Lattach, Youssef; Deronzier, Alain; Moutet, Jean-Claude

    2015-07-29

    The design of more efficient catalytic electrodes remains an important objective for the development of water splitting electrolyzers. In this context a structured composite cathode material has been synthesized by electrodeposition of molybdenum sulfide (MoSx) into a poly(pyrrole-alkylammonium) matrix, previously coated onto carbon electrodes by oxidative electropolymerization of a pyrrole-alkylammonium monomer. The composite material showed an efficient electrocatalytic activity toward proton reduction and the hydrogen evolution reaction (HER). Data from Tafel plots have demonstrated that the electron transfer rate in the composite films is fast, in agreement with the high catalytic activity of this cathode material. Bulk electrolysis of acidic water at carbon foam electrodes modified with the composite have shown that the cathodes display a high catalytic activity and a reasonable operational stability, largely exceeding that of regular amorphous MoSx electrodeposited on naked carbon foam. The enhanced catalytic performances of the composite electrode material were attributed to the structuration of the composite, which led to a homogeneous distribution of the catalyst on the carbon foam network, as shown by SEM characterizations.

  18. State of health estimation in composite electrode lithium-ion cells

    NASA Astrophysics Data System (ADS)

    Bartlett, Alexander; Marcicki, James; Rhodes, Kevin; Rizzoni, Giorgio

    2015-06-01

    Electrochemical models of lithium-ion batteries have been increasingly considered for online state of health estimation. These models can more accurately predict cell performance than traditional circuit models and can better relate physical degradation mechanisms to changes in model parameters. However, examples of state of health estimation algorithms that are validated with experimental data are scarce in the literature, particularly for cells with a composite electrode. The individual electrode active materials in a composite electrode may degrade at different rates and according to different physical mechanisms, and online estimation of this degradation facilitates more robust knowledge of how battery performance changes over its life. In this paper we use a reduced-order electrochemical model for a composite LiMn2O4-LiNi1/3Mn1/3 Co1/3O2 (LMO-NMC) electrode cell for online estimation of active material loss. Experimental data collected from composite electrode half cells that were aged under constant current cycling are used in an extended Kalman filter to estimate model parameters associated with loss of each active material. The capacity loss predicted by the online estimates agrees well with the measured capacity loss. Additionally, a differential capacity analysis demonstrates that active materials lose capacity at a similar rate, the same conclusion obtained from the online estimation algorithm.

  19. 21 CFR 884.2675 - Fetal scalp circular (spiral) electrode and applicator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Fetal scalp circular (spiral) electrode and... Gynecological Monitoring Devices § 884.2675 Fetal scalp circular (spiral) electrode and applicator. (a) Identification. A fetal scalp circular (spiral) electrode and applicator is a device used to obtain a...

  20. 21 CFR 884.2675 - Fetal scalp circular (spiral) electrode and applicator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Fetal scalp circular (spiral) electrode and... Gynecological Monitoring Devices § 884.2675 Fetal scalp circular (spiral) electrode and applicator. (a) Identification. A fetal scalp circular (spiral) electrode and applicator is a device used to obtain a...

  1. 21 CFR 884.2675 - Fetal scalp circular (spiral) electrode and applicator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Fetal scalp circular (spiral) electrode and... Gynecological Monitoring Devices § 884.2675 Fetal scalp circular (spiral) electrode and applicator. (a) Identification. A fetal scalp circular (spiral) electrode and applicator is a device used to obtain a...

  2. 21 CFR 884.2675 - Fetal scalp circular (spiral) electrode and applicator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Fetal scalp circular (spiral) electrode and... Gynecological Monitoring Devices § 884.2675 Fetal scalp circular (spiral) electrode and applicator. (a) Identification. A fetal scalp circular (spiral) electrode and applicator is a device used to obtain a...

  3. Nickel incorporated carbon nanotube/nanofiber composites as counter electrodes for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Joshi, Prakash; Zhou, Zhengping; Poudel, Prashant; Thapa, Amit; Wu, Xiang-Fa; Qiao, Qiquan

    2012-08-01

    A nickel incorporated carbon nanotube/nanofiber composite (Ni-CNT-CNF) was used as a low cost alternative to Pt as counter electrode (CE) for dye-sensitized solar cells (DSCs). Measurements based on energy dispersive X-rays spectroscopy (EDX) showed that the majority of the composite CE was carbon at 88.49 wt%, while the amount of Ni nanoparticles was about 11.51 wt%. Measurements based on electrochemical impedance spectroscopy (EIS) showed that the charge transfer resistance (Rct) of the Ni-CNT-CNF composite electrode was 0.71 Ω cm2, much lower than that of the Pt electrode (1.81 Ω cm2). Such a low value of Rct indicated that the Ni-CNT-CNF composite carried a higher catalytic activity than the traditional Pt CE. By mixing with CNTs and Ni nanoparticles, series resistance (Rs) of the Ni-CNT-CNF electrode was measured as 5.96 Ω cm2, which was close to the Rs of 5.77 Ω cm2 of the Pt electrode, despite the significant difference in their thicknesses: ~22 μm for Ni-CNT-CNF composite, while ~40 nm for Pt film. This indicated that use of a thick layer (tens of microns) of Ni-CNT-CNF counter electrode does not add a significant amount of resistance to the total series resistance (Rs-tot) in DSCs. The DSCs based on the Ni-CNT-CNF composite CEs yielded an efficiency of 7.96% with a short circuit current density (Jsc) of 15.83 mA cm-2, open circuit voltage (Voc) of 0.80 V, and fill factor (FF) of 0.63, which was comparable to the device based on Pt, that exhibited an efficiency of 8.32% with Jsc of 15.01 mA cm-2, Voc of 0.83, and FF of 0.67.

  4. 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.

  5. TCO/Ag/TCO transparent electrodes for solar cells application

    NASA Astrophysics Data System (ADS)

    Boscarino, S.; Crupi, I.; Mirabella, S.; Simone, F.; Terrasi, A.

    2014-09-01

    Among transparent electrodes, transparent conductive oxides (TCO)/metal/TCO structures can achieve optical and electrical performances comparable to, or better than, single TCO layers and very thin metallic films. In this work, we report on thin multilayers based on aluminum zinc oxide (AZO), indium tin oxide (ITO) and Ag deposited by RF magnetron sputtering on soda lime glass at room temperature. The TCO/Ag/TCO structures with thicknesses of about 50/10/50 nm were deposited with all combinations of AZO and ITO as top and bottom layers. While the electrical conductivity is dominated by the Ag intralayer irrespective of the TCO nature, the optical transmissions show a dependence on the nature of the top and bottom TCOs, mainly due to the change in the reflectivity of the multilayers. Structural, electrical and optical properties are studied to optimize the structure for very thin transparent electrodes suitable for photovoltaic applications.

  6. 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. PMID:26877029

  7. 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.

  8. Fabrication of ion-conducting carbon-polymer composite electrodes by spin-coating

    NASA Astrophysics Data System (ADS)

    Põldsalu, Inga; Mändmaa, Sven-Erik; Peikolainen, Anna-Liisa; Kesküla, Arko; Aabloo, Alvo

    2015-04-01

    We report a fabricating method for ion-conducting carbon electrodes on top of industrially produced PVDF membrane by spin-coating. Spin-coating is desirable due to its potential application in large-scale actuator manufacturing and its possibility to produce very thin electrodes. The industrial grade membrane was chosen in order to investigate more accurately the results of spin-coating without considering the deviations present in a hand-made membrane. Spin-coating and surface resistivity measurements via four-point probe were described in further detail. The production process of electrode suspension and suspension dispensing were developed and fine-tuned. The spin coater was programmed to obtain electrodes with uniform electrical properties. The arrangement of the spin coater was slightly altered to remove swelling and bubble formation effects concurrent with usage of the porous membrane. Electrodes produced with the developed method were measured and analyzed. Thickness of the film was measured with micrometer screw gauge and four-point probe was used to measure sheet resistivity, in addition film was studied under scanning electron microscope. In best cases the coefficient of variation for sheet conductivity was 6.2%. For all electrode sheet conductivities the median coefficient of variation was 7%. The thickness of the electrodes varied from 6 to 23 μm. As a proof of concept for the developed method a working actuator with spin-coated electrodes was produced.

  9. Perspectives on State-of-the-Art Carbon Nanotube/Polyaniline and Graphene/Polyaniline Composites for Hybrid Supercapacitor Electrodes.

    PubMed

    Srikanth, Vadali V S S; Ramana, Gedela Venkata; Kumar, Puttapati Sampath

    2016-03-01

    Supercapacitors are attractive alternative energy storage sources. They offer high energy/power density with other characteristics like fast discharge/charge time, long operation stability, safety etc. In a supercapacitor, working electrode material is the principal constituent. At present there are numerous electrode materials (with properties) suitable for their use in hybrid type supercapacitors. Carbon/polyaniline (PANi) composites are one class of such electrode materials. Here, perspectives on state-of-the-art carbon/PANi composites namely carbon nanotube/polyaniline and graphene/polyaniline composites expedient as hybrid type supercapacitor electrode materials will be presented. PMID:27455650

  10. Perspectives on State-of-the-Art Carbon Nanotube/Polyaniline and Graphene/Polyaniline Composites for Hybrid Supercapacitor Electrodes.

    PubMed

    Srikanth, Vadali V S S; Ramana, Gedela Venkata; Kumar, Puttapati Sampath

    2016-03-01

    Supercapacitors are attractive alternative energy storage sources. They offer high energy/power density with other characteristics like fast discharge/charge time, long operation stability, safety etc. In a supercapacitor, working electrode material is the principal constituent. At present there are numerous electrode materials (with properties) suitable for their use in hybrid type supercapacitors. Carbon/polyaniline (PANi) composites are one class of such electrode materials. Here, perspectives on state-of-the-art carbon/PANi composites namely carbon nanotube/polyaniline and graphene/polyaniline composites expedient as hybrid type supercapacitor electrode materials will be presented.

  11. Carbon-Nanotube-Based Electrodes for Biomedical Applications

    NASA Technical Reports Server (NTRS)

    Li, Jun; Meyyappan, M.

    2008-01-01

    A nanotube array based on vertically aligned nanotubes or carbon nanofibers has been invented for use in localized electrical stimulation and recording of electrical responses in selected regions of an animal body, especially including the brain. There are numerous established, emerging, and potential applications for localized electrical stimulation and/or recording, including treatment of Parkinson s disease, Tourette s syndrome, and chronic pain, and research on electrochemical effects involved in neurotransmission. Carbon-nanotube-based electrodes offer potential advantages over metal macroelectrodes (having diameters of the order of a millimeter) and microelectrodes (having various diameters ranging down to tens of microns) heretofore used in such applications. These advantages include the following: a) Stimuli and responses could be localized at finer scales of spatial and temporal resolution, which is at subcellular level, with fewer disturbances to, and less interference from, adjacent regions. b) There would be less risk of hemorrhage on implantation because nano-electrode-based probe tips could be configured to be less traumatic. c) Being more biocompatible than are metal electrodes, carbon-nanotube-based electrodes and arrays would be more suitable for long-term or permanent implantation. d) Unlike macro- and microelectrodes, a nano-electrode could penetrate a cell membrane with minimal disruption. Thus, for example, a nanoelectrode could be used to generate an action potential inside a neuron or in proximity of an active neuron zone. Such stimulation may be much more effective than is extra- or intracellular stimulation via a macro- or microelectrode. e) The large surface area of an array at a micron-scale footprint of non-insulated nanoelectrodes coated with a suitable electrochemically active material containing redox ingredients would make it possible to obtain a pseudocapacitance large enough to dissipate a relatively large amount of electric charge

  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. A Method for Efficient Transmittance Spectrum Prediction of Transparent Composite Electrodes

    NASA Astrophysics Data System (ADS)

    Zhao, Zhao; Dhar, A.; Alford, T. L.

    2015-07-01

    The interest in indium-free transparent composite electrode (TCE), a thin metal layer embedded between two transparent metal oxide (TMO) layers resulting in TMO/metal/TMO composite structure, has grown recently with the advent of their high figures of merit and its potential application in photovoltaic applications. However, most of the work to date has focused on experimentally producing the best optically transmitting TCE. To better design TCEs and minimize experimental work, it would be useful to develop a model that predicts the optical transmission. In the current work, the transfer-matrix method is employed to calculate the transmittance spectrum of TCE. To validate this approach, the transmittance spectra of TiO2/Au/TiO2 and TiO2/Ag/TiO2 multilayer thin-film TCEs are calculated with use of extracted material parameters. The calculated transmittance spectrum of TiO2/Au/TiO2 matches the measured spectrum quite well. However, the calcualted transmittance of TiO2/Ag/TiO2 is higher than its measured transmittance. The presence of voids in the Ag film is probably responsible for the decreased transmittance of the TiO2/Ag/TiO2 sample, and the continuous Au film in TiO2/Au/TiO2 ensures a good agreement between transmittance prediction and measurement. Our approach is a reliable tool to predict the optical transmittance of TCE with continuous films, and it can efficiently expedite the selection from numerous possible combinations of transparent metal oxides and metals when developing TCEs for future photovoltaic applications. It can also serve as a convenient method to assess the continuity of embedded metal layer.

  14. Solid contact potassium selective electrodes for biomedical applications - a review.

    PubMed

    van de Velde, L; d'Angremont, E; Olthuis, W

    2016-11-01

    Ion-selective electrodes (ISE) are used in several biomedical applications, including laboratory sensing of potassium concentration in blood and urine samples. For on-site determination of potassium concentration and usage in other applications such as determination of extracellular potassium concentration, miniaturization of the sensors is required. To that extent, solid contacts have proven to be an adequate substitute of liquid contacts as inner layer for ion-to-electron transduction, allowing industrial production of miniaturized ISEs. This review paper covers relevant developments of solid-state ISEs in the past decade, critically compares current potassium ISEs and discusses future prospects for biomedical applications. Performances of three main types of solid contact materials in potassium sensing are compared, namely polypyrrole, polythiophenes and conducting nanomaterials. With these new materials, numerous improvements in stability, selectivity and time response of solid-state ISEs have been made. Current developments are new operational methods of sensing, flexible miniaturized sensors and multi-electrode designs able to measure electrolyte concentrations in one-drop blood samples or transmembrane ionic flows. PMID:27591587

  15. Layered-double-hydroxide-modified electrodes: electroanalytical applications.

    PubMed

    Tonelli, Domenica; Scavetta, Erika; Giorgetti, Marco

    2013-01-01

    Two-dimensional inorganic solids, such as layered double hydroxides (LDHs), also defined as anionic clays, have open structures and unique anion-exchange properties which make them very appropriate materials for the immobilization of anions and biomolecules that often bear an overall negative charge. This review aims to describe the important aspects and new developments of electrochemical sensors and biosensors based on LDHs, evidencing the research from our own laboratory and other groups. It is intended to provide an overview of the various types of chemically modified electrodes that have been developed with these 2D layered materials, along with the significant advances made over the last several years. In particular, we report the main methods used for the deposition of LDH films on different substrates, the conductive properties of these materials, the possibility to use them in the development of membranes for potentiometric anion analysis, the early analytical applications of chemically modified electrodes based on the ability of LDHs to preconcentrate redox-active anions and finally the most recent applications exploiting their electrocatalytic properties. Another promising application field of LDHs, when they are employed as host structures for enzymes, is biosensing, which is described considering glucose as an example.

  16. 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.

  17. 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.

  18. Nanostructured Composite Electrodes for Lithium Batteries (Final Technical Report)

    SciTech Connect

    Meilin Liu, James Gole

    2006-12-14

    The objective of this study was to explore new ways to create nanostructured electrodes for rechargeable lithium batteries. Of particular interests are unique nanostructures created by electrochemical deposition, etching and combustion chemical vapor deposition (CCVD). Three-dimensional nanoporous Cu6Sn5 alloy has been successfully prepared using an electrochemical co-deposition process. The walls of the foam structure are highly-porous and consist of numerous small grains. This represents a novel way of creating porous structures that allow not only fast transport of gas and liquid but also rapid electrochemical reactions due to high surface area. The Cu6Sn5 samples display a reversible capacity of {approx}400 mAhg-1. Furthermore, these materials exhibit superior rate capability. At a current drain of 10 mA/cm2(20C rate), the obtainable capacity was more than 50% of the capacity at 0.5 mA/cm2 (1C rate). Highly open and porous SnO2 thin films with columnar structure were obtained on Si/SiO2/Au substrates by CCVD. The thickness was readily controlled by the deposition time, varying from 1 to 5 microns. The columnar grains were covered by nanoparticles less than 20 nm. These thin film electrodes exhibited substantially high specific capacity. The reversible specific capacity of {approx}3.3 mAH/cm2 was demonstrated for up to 80 cycles at a charge/discharge rate of 0.3 mA/cm2. When discharged at 0.9 mA/cm2, the capacity was about 2.1 mAH/cm2. Tin dioxide box beams or tubes with square or rectangular cross sections were synthesized using CCVD. The cross-sectional width of the SnO2 tubules was tunable from 50 nm to sub-micrometer depending on synthesis temperature. The tubes are readily aligned in the direction perpendicular to the substrate surface to form tube arrays. Silicon wafers were electrochemically etched to produce porous silicon (PS) with honeycomb-type channels and nanoporous walls. The diameters of the channels are about 1 to 3 microns and the depth of the

  19. Ink-jet printed porous composite LiFePO4 electrode from aqueous suspension for microbatteries

    NASA Astrophysics Data System (ADS)

    Delannoy, P.-E.; Riou, B.; Brousse, T.; Le Bideau, J.; Guyomard, D.; Lestriez, B.

    2015-08-01

    This work demonstrates ink-jet printed LiFePO4-based composite porous electrodes for microbattery application. As binder and dispersant, we found that aqueous inks with more suitable rheological properties with respect to ink-jet printing are prepared with the low molecular weight poly-acrylic-co-maleic acid copolymer, rather than with the carboxymethyl cellulose standard binder of the lithium-ion technology. The ink-jet printed thin and porous electrode shows very high rate charge/discharge behavior, both in LiPF6/ethylene carbonate-dimethyl carbonate (LP30) and lithium bis(trifluoromethane)sulfonylimide salt (Li-TFSI) in N-methyl-N-propylpyrrolidinium bis(trifluoromethane)suflonylimide ionic liquid (PYR13-TFSI) electrolytes, as well as good cyclability.

  20. Synthesis and Microstructural Characterization of Manganese Oxide Electrodes for Application as Electrochemical Supercapacitors

    NASA Astrophysics Data System (ADS)

    Babakhani, Banafsheh

    The aim of this thesis work was to synthesize Mn-based oxide electrodes with high surface area structures by anodic electrodeposition for application as electrochemical capacitors. Rod-like structures provide large surface areas leading to high specific capacitances. Since templated electrosynthesis of rods is not easy to use in practical applications, it is more desirable to form rod-like structures without using any templates. In this work, Mn oxide electrodes with rod-like structures (˜1.5 µm in diameter) were synthesized from a solution of 0.01 M Mn acetate under galvanostatic control without any templates, on Au coated Si substrates. The electrochemical properties of the synthesized nanocrystalline electrodes were investigated to determine the effect of morphology, chemistry and crystal structure on the corresponding electrochemical behavior of Mn oxide electrodes. Mn oxides prepared at different current densities showed a defective antifluoritetype crystal structure. The rod-like Mn oxide electrodes synthesized at low current densities (5 mAcm.2) exhibited a high specific capacitance due to their large surface areas. Also, specific capacity retention after 250 cycles in an aqueous solution of 0.5 M Na2SO4 at 100 mVs -1 was about 78% of the initial capacity (203 Fg-1 ). To improve the electrochemical capacitive behavior of Mn oxide electrodes, a sequential approach and a one-step method were adopted to synthesize Mn oxide/PEDOT electrodes through anodic deposition on Au coated Si substrates from aqueous solutions. In the former case, free standing Mn oxide rods (about 10 µm long and less than 1.5 µm in diameter) were first synthesized, then coated by electro-polymerization of a conducting polymer (PEDOT) giving coaxial rods. The one-step, co-electrodeposition method produced agglomerated Mn oxide/PEDOT particles. The electrochemical behavior of the deposits depended on the morphology and crystal structure of the fabricated electrodes, which were affected

  1. 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.

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

    PubMed

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

    2013-02-01

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

  3. Au nanoparticles/poly(caffeic acid) composite modified glassy carbon electrode for voltammetric determination of acetaminophen.

    PubMed

    Li, Tianbao; Xu, Juan; Zhao, Lei; Shen, Shaofei; Yuan, Maosen; Liu, Wenming; Tu, Qin; Yu, Ruijin; Wang, Jinyi

    2016-10-01

    An Au nanoparticles/poly(caffeic acid) (AuNPs/PCA) composite modified glassy carbon (GC) electrode was prepared by successively potentiostatic technique in pH 7.4 phosphate buffer solution containing 0.02mM caffeic acid and 1.0mM HAuCl4. Electrochemical characterization of the AuNPs/PCA-GC electrode was investigated by electrochemical impedance spectroscopy and cyclic voltammetry. The electrochemical behavior of acetaminophen (AP) at the AuNPs/PCA-GC electrode was also studied by cyclic voltammetry. Compared with bare GC and poly(caffeic acid) modified GC electrode, the AuNPs/PCA-GC electrode was exhibited excellent electrocatalytic activity toward the oxidation of AP. The plot of catalytic current versus AP concentration showed two linear segments in the concentration ranges 0.2-20µM and 50-1000µM. The detection limit of 14 nM was obtained by using the first range of the calibration plot. The AuNPs/PCA-GC electrode has been successfully applied and validated by analyzing AP in blood, urine and pharmaceutical samples. PMID:27474318

  4. Au nanoparticles/poly(caffeic acid) composite modified glassy carbon electrode for voltammetric determination of acetaminophen.

    PubMed

    Li, Tianbao; Xu, Juan; Zhao, Lei; Shen, Shaofei; Yuan, Maosen; Liu, Wenming; Tu, Qin; Yu, Ruijin; Wang, Jinyi

    2016-10-01

    An Au nanoparticles/poly(caffeic acid) (AuNPs/PCA) composite modified glassy carbon (GC) electrode was prepared by successively potentiostatic technique in pH 7.4 phosphate buffer solution containing 0.02mM caffeic acid and 1.0mM HAuCl4. Electrochemical characterization of the AuNPs/PCA-GC electrode was investigated by electrochemical impedance spectroscopy and cyclic voltammetry. The electrochemical behavior of acetaminophen (AP) at the AuNPs/PCA-GC electrode was also studied by cyclic voltammetry. Compared with bare GC and poly(caffeic acid) modified GC electrode, the AuNPs/PCA-GC electrode was exhibited excellent electrocatalytic activity toward the oxidation of AP. The plot of catalytic current versus AP concentration showed two linear segments in the concentration ranges 0.2-20µM and 50-1000µM. The detection limit of 14 nM was obtained by using the first range of the calibration plot. The AuNPs/PCA-GC electrode has been successfully applied and validated by analyzing AP in blood, urine and pharmaceutical samples.

  5. 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.

  6. 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.

  7. Effect of Electrode Composition and Microstructure on Impedancemetric Nitric Oxide Sensors based on YSZ Electrolyte

    SciTech Connect

    Woo, L Y; Martin, L P; Glass, R S; Wang, W; Jung, S; Gorte, R J; Murray, E P; Novak, R F; Visser, J H

    2007-04-02

    The role of metal (Au, Pt, and Ag) electrodes in YSZ electrolyte-based impedancemetric nitric oxide (NO) sensors is investigated using impedance spectroscopy and equivalent circuit analysis. The test cell consists of a rectangular block of porous YSZ with two metal wire loop electrodes, both exposed to the same atmosphere. Of the electrode materials, only Au was sensitive to changes in NO concentration. The impedance behavior of porous Au electrodes in a slightly different configuration was compared with dense Au electrodes and was also insensitive to NO. Ag showed no sensitivity to either O{sub 2} or NO, and the measured impedances occurred at frequencies > 10 kHz, which are typically associated with ionic conduction in YSZ. Pt and porous Au showed sensitivity to O{sub 2}, which was quantified using power-law exponents that suggest electrochemical rate-determining mechanisms occurring at the triple phase boundary. The behavior of the dense Au suggests different rate-determining processes (e.g., diffusion or adsorption) for the O{sub 2} reaction. Although the exact mechanism is not determined, the composition and microstructure of the metal electrode seem to alter the rate-limiting step of the interfering O{sub 2} reaction. Impedance behavior of the O{sub 2} reaction that is limited by processes occurring away from the triple phase boundary may be crucial for impedancemetric NO sensing.

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

    PubMed

    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

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

    PubMed

    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.

  10. 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

  11. Polymer composites for thermoelectric applications.

    PubMed

    McGrail, Brendan T; Sehirlioglu, Alp; Pentzer, Emily

    2015-02-01

    This review covers recently reported polymer composites that show a thermoelectric (TE) effect and thus have potential application as thermoelectric generators and Peltier coolers. The growing need for CO2-minimizing energy sources and thermal management systems makes the development of new TE materials a key challenge for researchers across many fields, particularly in light of the scarcity or toxicity of traditional inorganic TE materials based on Te and Pb. Recent reports of composites with inorganic and organic additives in conjugated and insulating polymer matrices are covered, as well as the techniques needed to fully characterize their TE properties. PMID:25537227

  12. Zinc oxide/activated carbon nanofiber composites for high-performance supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Kim, Chang Hyo; Kim, Bo-Hye

    2015-01-01

    ZnO-containing porous activated carbon nanofibers (ZnO/ACNFs) are prepared through one-step electrospinning using zinc acetate and polyacrylonitrile (PAN), followed by thermal treatment. The electrochemical performance of the ZnO/ACNF composite electrodes is compared to that of pure ACNF electrodes in aqueous KOH as the electrolyte. Electrochemical measurements of ZnO/ACNFs reveal a maximum specific capacitance of 178.2 Fg-1, and high energy densities of 22.71-17.77 Whkg-1 in the power density range of 400 to 4000 W kg-1. Furthermore, this supercapacitor electrode exhibits excellent cycle life with a specific capacitance ∼75% of the initial value after 1000 cycles. The combination of ACNF's high surface area with ZnO's large specific capacity facilitates a synergistic effect between ZnO's faradaic capacitance and ACNF's double layer capacitance, which afforded good capacitive behavior.

  13. Generation of electrochemiluminescence at bipolar electrodes: concepts and applications.

    PubMed

    Bouffier, Laurent; Arbault, Stéphane; Kuhn, Alexander; Sojic, Neso

    2016-10-01

    Bipolar electrochemistry (BPE) is an unconventional technique where a conducting object is addressed electrochemically in an electrolyte without any wire connection with an external power supply. BPE has been known for decades but remained limited to only a couple of niche applications. However, it is now undergoing a true renewal of interest especially in the context of analytical chemistry. The bipolar electrode exhibits two distinct poles of opposite polarization with respect to the solution. This allows one to separate the localization of sensing elements versus reporting ones. Also, arrays of bipolar microelectrodes can be addressed simultaneously to perform parallel analyses. Among several reporting strategies, the combination of BPE with electro-chemiluminescence (ECL) is the most frequent choice owing to the very simple visual readout provided by ECL. This article reviews the field from the initial reports to the most recent ones, revealing numerous opportunities including novel analytical strategies for the detection of small molecular analytes and biorelevant molecules such as DNA, RNA, peptides, or other biomarkers. Graphical Abstract Principle of electrochemiluminescence generation at one extremity of a bipolar electrode.

  14. Lamb Wave Characteristics of Composite Plates Including a Diamond Layer with Distinct Electrode Arrangements

    NASA Astrophysics Data System (ADS)

    Chen, Yung-Yu

    2013-07-01

    Diamond films have been utilized to develop surface acoustic wave filters and micromechanical resonators because of the highest acoustic wave velocity and largest product of frequency and quality factor (f.Q) of diamond among all materials. A theoretical analysis of Lamb wave characteristics in multilayer piezoelectric plates including a diamond layer is presented in this paper. Formulae for effective permittivity are derived using the transfer matrix method and are further employed to calculate Lamb wave phase velocity dispersions. The electromechanical coupling coefficients (ECCs) are also calculated exactly by Green's function method. Detailed calculations are carried out for ZnO/diamond and AlN/diamond composite plates with four distinct electrode arrangements. Results show that the ZnO/diamond structure yields a phase velocity of 6420 m/s and a large ECC of 7.41%, which makes it suitable for high-frequency wideband filter applications. Moreover, in the AlN/diamond structure, the S0 mode exhibits a large phase velocity of up to 10.3 km/s and a moderate ECC of 1.97%. Such favorable characteristics are expected to contribute to the development of AlN/diamond Lamb wave oscillators operating at approximately 5-10 GHz without the need for a sub-micrometer-resolution lithographic process. Therefore, both ZnO/diamond and AlN/diamond Lamb wave devices are highly promising candidates for RF devices in modern communication systems with advantages over conventional surface acoustic wave devices.

  15. 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.

  16. 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. PMID:23228492

  17. 2D Cross Sectional Analysis and Associated Electrochemistry of Composite Electrodes Containing Dispersed Agglomerates of Nanocrystalline Magnetite, Fe₃O₄.

    PubMed

    Bock, David C; Kirshenbaum, Kevin C; Wang, Jiajun; Zhang, Wei; Wang, Feng; Wang, Jun; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

    2015-06-24

    When electroactive nanomaterials are fully incorporated into an electrode structure, characterization of the crystallite sizes, agglomerate sizes, and dispersion of the electroactive materials can lend insight into the complex electrochemistry associated with composite electrodes. In this study, composite magnetite electrodes were sectioned using ultramicrotome techniques, which facilitated the direct observation of crystallites and agglomerates of magnetite (Fe3O4) as well as their dispersal patterns in large representative sections of electrode, via 2D cross sectional analysis by Transmission Electron Microscopy (TEM). Further, the electrochemistry of these electrodes were recorded, and Transmission X-ray Microscopy (TXM) was used to determine the distribution of oxidation states of the reduced magnetite. Unexpectedly, while two crystallite sizes of magnetite were employed in the production of the composite electrodes, the magnetite agglomerate sizes and degrees of dispersion in the two composite electrodes were similar to each other. This observation illustrates the necessity for careful characterization of composite electrodes, in order to understand the effects of crystallite size, agglomerate size, and level of dispersion on electrochemistry. PMID:26024206

  18. 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. PMID:24963504

  19. Electroadsorption Desalination with Carbon Nanotube/PAN-Based Carbon Fiber Felt Composites as Electrodes

    PubMed Central

    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. PMID:24963504

  20. 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.

  1. 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).

  2. 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.

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

    SciTech Connect

    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.

  4. Overview on macrofiber composite applications

    NASA Astrophysics Data System (ADS)

    Schönecker, Andreas J.; Daue, Thomas; Brückner, Bent; Freytag, Christian; Hähne, Ludwig; Rödig, Thomas

    2006-03-01

    Developed at NASA Langley Research Center during the late 90's, the Macro Fiber Composites (MFC) are manufactured by Smart Material Corp. in a full-scale production, today. Numerous research projects have proven the concept of using the MFC in vibration and noise control applications, as well as for health monitoring, morphing of structures and energy harvesting. Because basic performance parameters of products are considerably improved, like for example energy economy, precision and comfort, a widespread use of active structures is expected in the next future. Different MFC types are commercially available meeting already the requirements of a variety of applications. The migration from research projects to high volume, cost effective commercial applications has generated additional need for new MFC designs, electronics on microcontroller and chip level, and system design tools, as well. In this paper, we give an overview of recent progress in the development of the MFC transducers and MFC systems technology.

  5. 21 CFR 884.2685 - Fetal scalp clip electrode and applicator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Fetal scalp clip electrode and applicator. 884.2685 Section 884.2685 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... clip electrode and applicator is a device designed to establish electrical contact between fetal...

  6. Loading and utilization of active material in nickel composite electrodes: optimization

    SciTech Connect

    Lee, W.W.; Ferrando, W.A.; Sutula, R.A.

    1984-12-01

    As an attempt to reduce nickel battery weight, the nickel composite electrode, has been under development. Investigations were undertaken to determine the optimum conditions for loading and utilizing nickel hydroxide active material in nickel composite electrodes. The main emphasis was placed on the improvement of both loading efficiency by electrochemical impregnation and utilization efficiency of the Ni(OH)2 active material. The efficiencies were examined as functions of such electrochemical conditions as current density, nickel concentration, pH, temperature of the impregnating bath, the continuity of current flow and manner of adding Co(OH)S additive. Also studied was the loading efficiency of chemical impregnation (polarization method) and the suspension method which enables a direct loading of externally prepared active material into the composite body. The most important factor for a quick utilization of the active material was found to be the additive distribution. A model of the additive distribution in the active material is proposed to account for different patterns of utilization exhibited by the electrodes.

  7. 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

  8. 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.

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

    PubMed

    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

  10. Layered polyaniline composites with cation-exchanging properties for positive electrodes of rechargeable lithium batteries

    SciTech Connect

    Morita, Masayuki; Miyazaki, Seijiro; Ishikawa, Masashi; Matsuda, Yoshiharu . Dept. of Applied Chemistry and Chemical Engineering); Tajima, Hidehiko . Nagasaki Research and Development Center); Adachi, Kazuyuki; Anan, Fumimiasa . Research Lab.)

    1995-01-01

    Layered polyaniline/polyaniline-polyanion composite films (PAn-X/PAn-PA) were synthesized by electrochemical oxidation of aniline in aqueous acid solutions (HCl, HClO[sub 4]) followed by polymerization in poly(styrene-4-sulfonic acid) (PSSH) solutions. The films consist of inner polyaniline (PAn) layers doped with smaller size anions (X) and outer PSS-doped PAn layers. The resulting films showed high redox activities with cation-transfer properties in organic electrolyte solutions. The improved charge/discharge characteristics of the composite films gave an expectation of higher energy density for the full cell with lithium negative electrode.

  11. Three-dimensional microporous polypyrrole/polysulfone composite film electrode for supercapacitance performance

    NASA Astrophysics Data System (ADS)

    Feng, Xiaojuan; Shi, Yanlong; Jin, Shuping

    2015-10-01

    The three-dimensional microporous polypyrrole/polysulfone (PPY/PSF) composite film was fabricated via a simple polymerization method. The morphology structure and chemical composition of the composite film were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The electrochemical properties of the composite film electrode were evaluated by cyclic voltammetry, galvanostatic charging-discharging and electrochemical impedance spectroscopy. The material exhibits excellent capacitance performance including high capacitance of 500 F g-1 at 0.3 A g-1 current density, good cycle stability in 800 continuous cycles (only 4.5% decay after 800 cycles at 0.3 A g-1), and low inter resistance. The good property of the PPY/PSF electrode should be attributed to its structural features, including two-layer microporous structure which facilitates the penetration of electrolytes into the inner surface, high surface area which provides more active sites. These results show that the composite film is a promising candidate for high energy electrochemical capacitors.

  12. Electrochemically reduced graphene oxide/carbon nanotubes composites as binder-free supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Yang, Qin; Pang, Siu-Kwong; Yung, Kam-Chuen

    2016-04-01

    Binder-free composites of electrochemically reduced graphene oxide (ecrGO) and multiwalled carbon nanotubes (MWCNTs) were fabricated as supercapacitors electrodes operating in aqueous systems. GO was found to be electrochemically reduced according to the XRD and Raman data. Therefore, this facile and controllable method was applied to reduce GO in the GO/MWCNTs composites, generating ecrGO/MWCNTs composites. The ecrGO/MWCNTs composites exhibit higher specific capacitance (Csp) than ecrGO because the intercalation of MWCNTs into ecrGO sheets increases the surface areas, according to the TEM, XRD and N2 adsorption-desorption results. The composites with different mass ratios of GO to MWCNTs (10:1, 5:1, 1:1, 1:5, 1:10) were investigated. The ecrGO/MWCNTs composite (GO: MWCNTs = 5:1) showed the highest Csp from the cyclic voltammetry results at a scan rate of 10 mV s-1, and it expressed Csp of 165 F g-1 at a current density of 1 A g-1 and 93% retention after 4000 cycles of charge/discharge. When the mass ratio of GO to MWCNTs further decreases to 1:10, the Csp of the composites declines, and the ecrGO/MWCNTs composite (GO: MWCNTs = 1:10) performs a nearly pure double-layer capacitor. However, the composites containing more MWCNTs can maintain better capacitive behavior at higher rates of charge/discharge.

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

    PubMed

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

    2016-03-30

    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(-1)electrode (∼393 mAh cm(-3)electrode) 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.

  14. 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

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

    PubMed

    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(-1)electrode (∼393 mAh cm(-3)electrode) 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

  16. 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.

  17. Electrochemical Preparation and Characterization of a Gold Nanoparticles Graphite Electrode: Application to Myricetin Antioxidant Analysis.

    PubMed

    Ng, Khan Loon; Lee, See Mun; Khor, Sook Mei; Tan, Guan Huat

    2015-01-01

    Graphite material is abundantly available from recyclable sources. It possesses a good electrical conductance property, which makes it an attractive material as a working electrode. However, due to a high activation overpotential it has limited applications as compared to other solid metal electrodes. In this present work, we obtained a graphite rod from a used battery, and carried out electrochemical improvements by electro-deposition with gold nanoparticles (AuNPs). The heterogeneous electron transfer rate and electron transfer resistance of the fabricated electrode were improved. The electrode overpotential has shown improvement by 50 mV, and the effective surface area has increased by 2 fold. To determine the practicability of the AuNPs/graphite electrode, we used the electrode in the analysis of myricetin. A square-wave voltammetry was used in the analysis, and the detection response increased by 2.5 fold, which suggested an improvement in the electrode sensitivity.

  18. Three-dimensional graphene-based composites for energy applications

    NASA Astrophysics Data System (ADS)

    Mao, Shun; Lu, Ganhua; Chen, Junhong

    2015-04-01

    Three-dimensional (3D) graphene-based composites have drawn increasing attention for energy applications due to their unique structures and properties. By combining the merits of 3D graphene (3DG), e.g., a porous and interconnected network, a high electrical conductivity, a large accessible surface area, and excellent mechanical strength and thermal stability, with the high chemical/electrochemical activities of active materials, 3DG-based composites show great promise as high-performance electrode materials in various energy devices. This article reviews recent progress in 3DG-based composites and their applications in energy storage/conversion devices, i.e., supercapacitors, lithium-ion batteries, dye-sensitized solar cells, and fuel cells.

  19. Determination of dopamine in synthetic cerebrospinal fluid by SWV with a graphite-polyurethane composite electrode.

    PubMed

    de Toledo, R A; Santos, M C; Cavalheiro, E T G; Mazo, L H

    2005-03-01

    This work describes an electroanalytical investigation of dopamine using cyclic voltammetry (CV) and the graphite-polyurethane composite electrode (GPU). In CV studies, well-defined redox peaks characterize the oxidation process at the GPU electrode, which is indicative of electrocatalytic effects associated with active sites on the GPU electrode surface. A new analytical methodology was developed using the GPU electrode and square wave voltammetry (SWV) in BR buffer solution (0.1 mol L(-1); pH 7.4). Analytical curves were constructed under optimized conditions (f=60s(-1), DeltaE(a)=50 mV, DeltaE(I)=2 mV) and detection and quantification limits of 6.4x10(-8) mol L(-1) (12.1 microg L(-1)) and 5.2x10(-6) mol L(-1) (0.9 mg L(-1)), respectively, were achieved. The precision of the method was checked by performing ten successive measurements for a 9.9x10(-6) mol L(-1) dopamine solution. For intra-assay and inter-assay precisions, the relative standard deviations were 1.9 and 2.3%, respectively. In order to evaluate the developed methodology, the determination of dopamine was performed with good sensitivity and selectivity, without the interference of ascorbic acid in synthetic cerebrospinal fluid, which indicates that the new methodology enables reliable analysis of dopamine. PMID:15714300

  20. Solid electrodes in electroanalytical chemistry: present applications and prospects for high throughput screening of drug compounds.

    PubMed

    Uslu, Bengi; Ozkan, Sibel A

    2007-08-01

    This review summarizes recent progress in the development and application of solid electrodes to the screening of pharmaceutical dosage forms and biological fluids. Recent trends and advances in the electroanalytical chemistry of solid electrodes, microelectrodes and electrochemical sensors are reviewed. The varieties of solid electrodes and their basic physico-chemical properties and some specific characteristics including some supramolecular phenomena at their surface are surveyed. This review also includes some selected designs and their applications. Despite many reviews about individual solid electrodes in the literature, this review offers the first comprehensive report on all forms of solid electrodes. Special attention is paid to the possibilities of solid electrodes in high throughput electroanalytical investigation of drug dosage forms and biological samples using modern electroanalytical techniques. Various selected studies on these subjects since 1996 are reviewed in this paper.

  1. Composite materials for fusion applications

    SciTech Connect

    Jones, R.H.; Henager, C.H. Jr.; Hollenberg, G.W.

    1991-10-01

    Ceramic matrix composites, CMCs, are being considered for advanced first-wall and blanket structural applications because of their high-temperature properties, low neutron activation, low density and low coefficient of expansion coupled with good thermal conductivity and corrosion behavior. This paper presents a review and analysis of the hermetic, thermal conductivity, corrosion, crack growth and radiation damage properties of CMCs. It was concluded that the leak rates of a gaseous coolant into the plasma chamber or tritium out of the blanket could exceed design criteria if matrix microcracking causes existing porosity to become interconnected. Thermal conductivities of unirradiated SiC/SiC and C/SiC materials are about 1/2 to 2/3 that of Type 316 SS whereas the thermal conductivity for C/C composites is seven times larger. The thermal stress figure-of-merit value for CMCs exceeds that of Type 316 SS for a single thermal cycle. SiC/SiC composites are very resistant to corrosion and are expected to be compatible with He or Li coolants if the O{sub 2} concentrations are maintained at the appropriate levels. CMCs exhibit subcritical crack growth at elevated temperatures and the crack velocity is a function of the corrosion conditions. The radiation stability of CMCs will depend on the stability of the fiber, microcracking of the matrix, and the effects of gaseous transmutation products on properties. 23 refs., 14 figs., 1 tab.

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

    DOE PAGES

    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 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

  3. Composites applications - The future is now

    SciTech Connect

    Drozda, T.J.

    1989-01-01

    The present volume on the development status of advanced composites discusses resin-, ceramic- and metal-matrix composites, as well as tooling practices, testing and inspection methods, and novel applications. Attention is given to interface considerations in ceramic-matrix composites, applications of metal-matrix composites to military aircraft, advanced thermoplastic preforms, tooling for filament-winding processes, trapped-rubber molding methods, pultrusion for automotive applications, and composite-production tooling using CAD/CAM. Also discussed are expert systems for composites inspection and repair, acoustographic high-speed NDE for composites, the design and production of a composite landing gear-retracting beam, braided composite structures, and the uses of composites in orthopedics.

  4. 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.

  5. Nano crystalline palladium disposable electrode development for electrochemical spectroscopy application

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Su, Chien-Hao; Chen, Peng-Jen; Hsu, Kuo-Chen; Chang, Chia-Ching; Cheeshin Technology Co. Collaboration

    Electrochemical spectroscopy is a highly sensitive and selective detection method to revealing the intermolecular interaction. Gold electrode provides excellent charge transfer property and has been widely used in electrochemical analysis. However, gold electrode is expensive. Moreover, it is time consuming and complicated to regenerate a reaction active gold electrode. Therefore, a ready-to-use electrode is highly desired for electrochemical analysis. In this study, we have developed a novel nano-crystalline palladium (Pd) film electrode which is deposited on flexible polyethylene terephthalate (PET) by sputtering. This Pd electrode is as good as well prepared gold electrode both in cyclic voltammetry (CV) and electric impedance spectroscopy (EIS) due to its highly dispersive {1 1 1}facets-exposed nanocrystalline Pd on high quality. By using this ready-to-use Pd film electrode, the interactions between DNA and drugs can be detected at sub-nanogram level. This research is supported by MOST 104-2622-M-009-002-CC2; Corresponding author: Chia-Ching Chang; ccchang01@faculty.nctu.edu.tw.

  6. Carbon nanotubes reinforced composites for biomedical applications.

    PubMed

    Wang, Wei; Zhu, Yuhe; Liao, Susan; Li, Jiajia

    2014-01-01

    This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites), their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo.

  7. Carbon Nanotubes Reinforced Composites for Biomedical Applications

    PubMed Central

    Wang, Wei; Zhu, Yuhe; Liao, Susan; Li, Jiajia

    2014-01-01

    This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites), their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo. PMID:24707488

  8. Electrochemical preparation of sodium dodecylsulfate doped over-oxidized polypyrrole/multi-walled carbon nanotube composite on glassy carbon electrode and its application on sensitive and selective determination of anticancer drug: pemetrexed.

    PubMed

    Karadas, Nurgul; Ozkan, Sibel A

    2014-02-01

    Electrochemical oxidation of pemetrexed (PMX) was studied on bare, carboxylic acid functionalized multi-walled carbon nanotubes and over-oxidized polypyrrole modified (oo-PPy/MWCNTs-COOH/GCE) glassy carbon electrodes by cyclic and adsorptive stripping differential pulse voltammetric techniques. The oo-PPy/MWCNTs-COOH/GCE is very sensitive to the oxidation of PMX. The results proved that the over-oxidation of the PPy film gave a negative charge density on porous layer that improved the adsorption for PMX. The effects of pH, concentrations of MWCNTs and monomer, the number of cycles for the electropolymerization and the scan rate for sensor preparation were optimized. The MWCNTs-COOH and oo-PPy based sensor showed an excellent recognition capacity toward PMX. The linear responses have been obtained in the range from 8.00 × 10(-7)M to 1.00 × 10(-4)M with 2.04 × 10(-7)M detection limit for the bare GCE and from 1.00 × 10(-8)M to 1.00 × 10(-7)M with 3.28 × 10(-9)M detection limit for the modified GCE. The oxidation of PMX was controlled by the adsorption process on both types of electrode surfaces. The proposed methods were compared with the literature on UV spectrophotometric assay, which was carried out at an absorption maximum of 225 nm. The proposed method and the designed sensors have been successfully applied for the determination of PMX in pharmaceuticals.

  9. Electrochemical preparation of sodium dodecylsulfate doped over-oxidized polypyrrole/multi-walled carbon nanotube composite on glassy carbon electrode and its application on sensitive and selective determination of anticancer drug: pemetrexed.

    PubMed

    Karadas, Nurgul; Ozkan, Sibel A

    2014-02-01

    Electrochemical oxidation of pemetrexed (PMX) was studied on bare, carboxylic acid functionalized multi-walled carbon nanotubes and over-oxidized polypyrrole modified (oo-PPy/MWCNTs-COOH/GCE) glassy carbon electrodes by cyclic and adsorptive stripping differential pulse voltammetric techniques. The oo-PPy/MWCNTs-COOH/GCE is very sensitive to the oxidation of PMX. The results proved that the over-oxidation of the PPy film gave a negative charge density on porous layer that improved the adsorption for PMX. The effects of pH, concentrations of MWCNTs and monomer, the number of cycles for the electropolymerization and the scan rate for sensor preparation were optimized. The MWCNTs-COOH and oo-PPy based sensor showed an excellent recognition capacity toward PMX. The linear responses have been obtained in the range from 8.00 × 10(-7)M to 1.00 × 10(-4)M with 2.04 × 10(-7)M detection limit for the bare GCE and from 1.00 × 10(-8)M to 1.00 × 10(-7)M with 3.28 × 10(-9)M detection limit for the modified GCE. The oxidation of PMX was controlled by the adsorption process on both types of electrode surfaces. The proposed methods were compared with the literature on UV spectrophotometric assay, which was carried out at an absorption maximum of 225 nm. The proposed method and the designed sensors have been successfully applied for the determination of PMX in pharmaceuticals. PMID:24401411

  10. 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.

  11. 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.

  12. 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

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Application of Carbon Nanomaterials in Lithium-Ion Battery Electrodes

    NASA Astrophysics Data System (ADS)

    Jaber-Ansari, Laila

    Carbon nanomaterials such as single-walled carbon nanotubes (SWCNTs) and graphene have emerged as leading additives for high capacity nanocomposite lithium ion battery electrodes due to their ability to improve electrode conductivity, current collection efficiency, and charge/discharge rate for high power applications. In this work, the these nanomaterials have been developed and their properties have been fine-tuned to help solve fundamental issues in conventional lithium ion battery electrodes. Towards this end, the application of SWCNTs in lithium-ion anodes has been studied. As-grown SWCNTs possess a distribution of physical and electronic structures, and it is of high interest to determine which subpopulations of SWCNTs possess the highest lithiation capacity and to develop processing methods that can enhance the lithiation capacity of underperforming SWCNT species. Towards this end, SWCNT electronic type purity is controlled via density gradient ultracentrifugation, enabling a systematic study of the lithiation of SWCNTs as a function of metal versus semiconducting content. Experimentally, vacuum filtered freestanding films of metallic SWCNTs are found to accommodate lithium with an order of magnitude higher capacity than their semiconducting counterparts. In contrast, SWCNT film densification leads to the enhancement of the lithiation capacity of semiconducting SWCNTs to levels comparable to metallic SWCNTs, which is corroborated by theoretical calculations. To understand the interaction of the graphene with lithium ions and electrolyte species during electrochemical we use Raman spectroscopy in a model system of monolayer graphene transferred on a Si(111) substrate and density functional theory (DFT) to investigate defect formation as a function of lithiation. This model system enables the early stages of defect formation to be probed in a manner previously not possible with commonly-used reduced graphene oxide or multilayer graphene substrates. Using ex

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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.

  16. 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. PMID:26314271

  17. Fabrication of a nano-structured PbO2 electrode by using printing technology: Surface characterization and application

    NASA Astrophysics Data System (ADS)

    Kannan, K.; Muthuraman, G.; Cho, G.; Moon, I. S.

    2014-08-01

    This investigation aimed to introduce printing technology for the first time to prepare a nanostrucutured PbO2 electrode and its application to a cerium redox transfer process. The new method of nano-size PbO2 preparation demonstrated that nano-PbO2 could be obtained in less time and at less cost at room temperature. The prepared nano-PbO2 screen printed on a Ti electrode by three different compositions under similar conditions showed through surface and electrochemical analyses no adherence on Ti and no contact with other nano-PbO2 particles. Gravure printing of nano-PbO2 on a PET (poly ethylene thin) film at high pressure was done with two different compositions for the first time. The selective composition of 57.14 % nano-PbO2 powder with 4.28 % carbon black and 38.58 % ECA (ethyl carbitol acetate) produced a film with a nanoporous structure with an electron transfer ability. Finally, the optimized gravure-printed nano-PbO2 electrode was applied to the oxidation of Ce(III) to Ce(IV) by using cyclic voltammetry. The gravure-printed nano-PbO2 should pave the way to promising applications in electrochemical and sensor fields.

  18. 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.

  19. A New Composition for Co(II)-porphyrin-based Membranes Used in Thiocyanate-selective Electrodes

    PubMed Central

    Vlascici, Dana; Fagadar-Cosma, Eugenia; Bizerea-Spiridon, Otilia

    2006-01-01

    In the present paper, the potentiometric response characteristics of a metalloporphyrin-based electrode in o-nitrophenyloctylether (o-NPOE) plasticized polyvinyl chloride (PVC) membrane are presented for a set of monovalent anions. As membrane ionophore, 5,10,15,20-tetrakis-(4-methoxyphenyl)-porphyrin-Co(II) (CoTMeOPP) was used. To establish the optimum composition of the membrane, different molar percents of cationic derivative (mol.% relative to ionophore) were used. Electrodes formulated with membranes containing 1 wt.% ionophore, 66 wt.% o-NPOE, 33 wt.% PVC (plasticizer: PVC = 2:1) and the lipophilic cationic derivative (35 mol%) are shown to exhibit high selectivity for thiocyanate with a near-Nernstian slope in the working concentration range of 1.0×10−1–1.0×10−5 M, with a good stability in time.

  20. Electrochemical Oxidation and Determination of Oxalic Acid at an Exfoliated Graphite-Polystyrene Composite Electrode

    PubMed Central

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

    2007-01-01

    An exfoliated graphite-polystyrene composite electrode was evaluated as an alternative electrode in the oxidation and the determination of oxalic acid in 0.1 M Na2SO4 supporting electrolyte. Using CV, LSV, CA procedures, linear dependences I vs. C were obtained in the concentrations range of oxalic acid between 0.5 to 3 mM, with LOD =0.05 mM, and recovery degree of 98%, without need of surface renewing between successive runs. The accuracy of the methods was evaluated as excellent comparing the detection results with that obtained using conventional KMnO4 titration method. In addition, the apparent diffusion coefficient of oxalic acid D was found to be around 2.89 · 10-8 cm2·s-1 by CA and CV.

  1. Application of Carbon Nanomaterials in Lithium-Ion Battery Electrodes

    NASA Astrophysics Data System (ADS)

    Jaber-Ansari, Laila

    Carbon nanomaterials such as single-walled carbon nanotubes (SWCNTs) and graphene have emerged as leading additives for high capacity nanocomposite lithium ion battery electrodes due to their ability to improve electrode conductivity, current collection efficiency, and charge/discharge rate for high power applications. In this work, the these nanomaterials have been developed and their properties have been fine-tuned to help solve fundamental issues in conventional lithium ion battery electrodes. Towards this end, the application of SWCNTs in lithium-ion anodes has been studied. As-grown SWCNTs possess a distribution of physical and electronic structures, and it is of high interest to determine which subpopulations of SWCNTs possess the highest lithiation capacity and to develop processing methods that can enhance the lithiation capacity of underperforming SWCNT species. Towards this end, SWCNT electronic type purity is controlled via density gradient ultracentrifugation, enabling a systematic study of the lithiation of SWCNTs as a function of metal versus semiconducting content. Experimentally, vacuum filtered freestanding films of metallic SWCNTs are found to accommodate lithium with an order of magnitude higher capacity than their semiconducting counterparts. In contrast, SWCNT film densification leads to the enhancement of the lithiation capacity of semiconducting SWCNTs to levels comparable to metallic SWCNTs, which is corroborated by theoretical calculations. To understand the interaction of the graphene with lithium ions and electrolyte species during electrochemical we use Raman spectroscopy in a model system of monolayer graphene transferred on a Si(111) substrate and density functional theory (DFT) to investigate defect formation as a function of lithiation. This model system enables the early stages of defect formation to be probed in a manner previously not possible with commonly-used reduced graphene oxide or multilayer graphene substrates. Using ex

  2. 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.

  3. 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. PMID:22519122

  4. 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.

  5. 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.

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

    SciTech Connect

    Marina, Olga A; Stevenson, Jeffry W

    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.

  7. 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.

  8. Industrial applications of multiaxial warp knit composites

    NASA Technical Reports Server (NTRS)

    Kaufmann, James R.

    1992-01-01

    Over the past few years, multiaxial warp knit (MWK) fabrics have made significant inroads into the industrial composites arena. This paper examines the use of MWK fabrics in industrial composite applications. Although the focus is on current applications of MWK fabrics in composites, this paper also discusses the physical properties, advantages and disadvantages of MWK fabrics. The author also offers possibilities for the future of MWK fabrics in the industrial composites arena.

  9. Application of gas diffusion electrodes in bioelectrochemical syntheses and energy conversion.

    PubMed

    Horst, Angelika E W; Mangold, Klaus-Michael; Holtmann, Dirk

    2016-02-01

    Combining the advantages of biological components (e.g., reaction specificity, self-replication) and electrochemical techniques in bioelectrochemical systems offers the opportunity to develop novel efficient and sustainable processes for the production of a number of valuable products. The choice of electrode material has a great impact on the performance of bioelectrochemical systems. In addition to the redox process at the electrodes, interactions of biocatalysts with electrodes (e.g., enzyme denaturation or biofouling) need to be considered. In recent years, gas diffusion electrodes (GDEs) have proved to be very attractive electrodes for bioelectrochemical purposes. GDEs are porous electrodes, that posses a large three-phase boundary surface. At this interface, a solid catalyst supports the electrochemical reaction between gaseous and liquid phase. This mini-review discusses the application of GDEs in microbial and enzymatic fuel cells, for microbial electrolysis, in biosensors and for electroenzymatic synthesis reactions.

  10. Electrodes for bio-application: recording and stimulation

    NASA Astrophysics Data System (ADS)

    Fontes, M. B. A.

    2013-03-01

    Recording and stimulation electrodes applied on excitable tissue are the basis of electrophysiological research, such as brain, muscles, peripheral nerves or sensory systems. Electrode-electrolyte impedance is one of the important characteristics due to its influence on the signal/noise ratio, signal distortion and built-up voltage. Strategies to lowering and tuning the impedance are achieved by biasing iridium oxide modified platinum microelectrodes. Surface and impedance analysis after pulse stimulation are also addressed.

  11. A biosensor based on graphite epoxy composite electrode for aspartame and ethanol detection.

    PubMed

    Kirgöz, Ulkü Anik; Odaci, Dilek; Timur, Suna; Merkoçi, Arben; Alegret, Salvador; Beşün, Nurgün; Telefoncu, Azmi

    2006-06-16

    A gelatin membrane with carboxyl esterase and alcohol oxidase was subsequently integrated onto the surface of a graphite epoxy composite electrode (GECE). The developed biosensors showed linearity in the range of 2.5-400 microM for aspartame and 2.5-25 microM for ethanol with response times of 170 and 70s for each analyte, respectively. The resulting bienzyme biosensor was used for aspartame detection in diet coke samples and ethanol detection in beer and wine samples. From the obtained results, it can be concluded that the developed biosensor is a selective, practical and economic tool for aspartame and ethanol detection in real samples.

  12. Preparation, applications, and digital simulation of carbon interdigitated array electrodes.

    PubMed

    Liu, Fei; Kolesov, Grigory; Parkinson, B A

    2014-08-01

    Carbon interdigitated array (IDA) electrodes with features sizes down to 1.2 μm were fabricated by controlled pyrolysis of patterned photoresist. Cyclic voltammetry of reversible redox species produced the expected steady-state currents. The collection efficiency depends on the IDA electrode spacing, which ranged from around 2.7 to 16.5 μm, with the smaller dimensions achieving higher collection efficiencies of up to 98%. The signal amplification because of redox cycling makes it possible to detect species at relatively low concentrations (10(-5) molar) and the small spacing allows detection of transient electrogenerated species with much shorter lifetimes (submillisecond). Digital simulation software that accounts for both the width and height of electrode elements as well as the electrode spacing was developed to model the IDA electrode response. The simulations are in quantitative agreement with experimental data for both a simple fast one electron redox reaction and an electron transfer with a following chemical reaction at the IDAs with larger gaps whereas currents measured for the smallest IDA electrodes, that were larger than the simulated currents, are attributed to convection from induced charge electrokinetic flow. PMID:24998907

  13. Preparation, Applications, and Digital Simulation of Carbon Interdigitated Array Electrodes

    SciTech Connect

    Liu, Fei; Kolesov, Grigory; Parkinson, Bruce A.

    2014-12-16

    Carbon interdigitated array (IDA) electrodes with features sizes down to 1.2 μm were fabricated by controlled pyrolysis of patterned photoresist. Cyclic voltam-metry of reversible redox species produced the expected steady-state currents. The collection efficiency depends on the IDA electrode spacing, which ranged from around 2.7 to 16.5 μm, with the smaller dimensions achieving higher collection efficiencies of up to 98%. The signal amplification because of redox cycling makes it possible to detect species at relatively low concentrations (10–5 molar) and the small spacing allows detection of transient electrogenerated species with much shorter lifetimes (submillisecond). Digital simulation software that accounts for both the width and height of electrode elements as well as the electrode spacing was developed to model the IDA electrode response. The simulations are in quantitative agreement with experimental data for both a simple fast one electron redox reaction and an electron transfer with a following chemical reaction at the IDAs with larger gaps whereas currents measured for the smallest IDA electrodes, that were larger than the simulated currents, are attributed to convection from induced charge electrokinetic flow. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the Department of Energy, Office of Science Office of Basic Energy Sciences.

  14. Novel semi-dry electrodes for brain-computer interface applications

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Li, Guangli; Chen, Jingjing; Duan, Yanwen; Zhang, Dan

    2016-08-01

    Objectives. Modern applications of brain-computer interfaces (BCIs) based on electroencephalography rely heavily on the so-called wet electrodes (e.g. Ag/AgCl electrodes) which require gel application and skin preparation to operate properly. Recently, alternative ‘dry’ electrodes have been developed to increase ease of use, but they often suffer from higher electrode-skin impedance and signal instability. In the current paper, we have proposed a novel porous ceramic-based ‘semi-dry’ electrode. The key feature of the semi-dry electrodes is that their tips can slowly and continuously release a tiny amount of electrolyte liquid to the scalp, which provides an ionic conducting path for detecting neural signals. Approach. The performance of the proposed electrode was evaluated by simultaneous recording of the wet and semi-dry electrodes pairs in five classical BCI paradigms: eyes open/closed, the motor imagery BCI, the P300 speller, the N200 speller and the steady-state visually evoked potential-based BCI. Main results. The grand-averaged temporal cross-correlation was 0.95 ± 0.07 across the subjects and the nine recording positions, and these cross-correlations were stable throughout the whole experimental protocol. In the spectral domain, the semi-dry/wet coherence was greater than 0.80 at all frequencies and greater than 0.90 at frequencies above 10 Hz, with the exception of a dip around 50 Hz (i.e. the powerline noise). More importantly, the BCI classification accuracies were also comparable between the two types of electrodes. Significance. Overall, these results indicate that the proposed semi-dry electrode can effectively capture the electrophysiological responses and is a feasible alternative to the conventional dry electrode in BCI applications.

  15. The natural diatomite from caldiran-van (Turkey): electroanalytical application to antimigraine compound naratriptan at modified carbon paste electrode.

    PubMed

    Calışkan, Necla; Sögüt, Eda; Saka, Cafer; Yardım, Yavuz; Sentürk, Zuhre

    2010-09-01

    This paper is the first report describing the characterization of local diatomite of Caldiran-Van region (Eastern Anatolia, Turkey). Special attention was paid to the ability of its electroanalytical performance at modified electrodes and to the potential application of diatomite-modified electrode. For this purpose, the determination of Naratriptan which is a novel oral triptan (5-hydroxytryptamine receptor agonist) in migraine treatment, by means of a carbon paste electrode modified with 10% (w/w) of diatomite was studied using cyclic and square-wave voltammetry. The experimental conditions that affect the electrode reaction process were studied in terms of pH of the supporting electrolyte, scan rate, accumulation variables, modifier composition and square-wave parameters. Using square-wave stripping mode, the drug yielded a well-defined voltammetric response in Britton-Robinson buffer, pH 4.0 at 0.84 V (vs. Ag/AgCl) (a pre-concentration step being carried out with an open circuit at 120 s). The process could be used to determine Naratriptan concentrations in the range 5x10(-7)-9x10(-7) M, with a detection limit of 1.25x10(-7) M (46.5 mug L(-1)). The applicability of the method to spiked human urine samples was illustrated.

  16. Composition and cycle life of multicomponent AB{sub 5} hydride electrodes

    SciTech Connect

    Adzic, G.D.; Johnson, J.R.; Reilly, J.J.; McBreen, J.; Mukerjee, S.; Kumar, M.P.S.; Zhang, W.; Srinivasan, S.

    1994-11-01

    Multicomponent AB{sub 5} hydrides are attractive replacements for the cadmium electrode in nickel -- cadmium batteries. The archetype compound of the AB{sub 5} alloy class is LaNi{sub 5}, but in a typical battery electrode mischmetal is substituted for La and Ni is substituted in part by variety of metals. While the effects of Ni substitution have been widely studied, relatively little effort has focused on the effect of La substitution. This paper deals with the effect on cycle life due to the increasing presence of Ce in the alloy series La{sub 1-x}Ce{sub x}Ni{sub 3.55}Co{sub .75}Mn{sub .4}Al{sub .3}. Alloys were characterized by the determination of pressure-composition relationships, molar volume of H and electrode cycle life. The effects due to lattice expansion are taken into account. It was concluded that the rate of loss of electrochemical capacity per charge/discharge cycle was significantly decreased due to the presence of Ce.

  17. 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.

  18. Pseudo-capacitance of composite electrode of ruthenium oxide with porous carbon in non-aqueous electrolyte containing imidazolium salt

    NASA Astrophysics Data System (ADS)

    Egashira, Minato; Matsuno, Yuki; Yoshimoto, Nobuko; Morita, Masayuki

    Pseudo-capacitance of composite materials where ruthenium oxide particles are loaded on activated carbon has been evaluated in the electrolyte of 1-ethyl-3-methyl imidazolium tetrafluoroborate dissolved in acetonitrile. The composite materials prepared by conventional a sol-gel method have dispersed structure of ruthenium oxide particle of tens nanometer diameter on the surface of activated carbon. The extent of the pseudo-capacitance of the composite electrodes in the imidazolium salt electrolyte, estimated by the comparison of the capacitance per surface area of electrode in different non-aqueous electrolyte, is ca. 3-5 μF cm -2 in addition to the double-layer capacitance of ca. 6 μF cm -2, depending on the loading status of ruthenium oxide. The symmetric cell consisting of the composite electrode containing 18 wt% of ruthenium oxide and the imidazolium salt electrolyte provides cell capacitance based on the pseudo-capacitance by a constant-current test.

  19. Gold-nanoparticle-embedded nafion composite modified on glassy carbon electrode for highly selective detection of arsenic(III).

    PubMed

    Huang, Jing-Fang; Chen, Hsiao-Hua

    2013-11-15

    A Cu(I)-ion-mediating Au reduction is proposed for preparing an Au-nanoparticle-embedded nafion (NF(Aunano)) composite. The NF(Aunano) composite consisted of highly dense, well-dispersed, and protecting-agent-free Au nanocrystals with a narrow particle size (4.8±0.1 nm) distribution. The NF(Aunano) composite was characterized as a function of composition and particle size distribution using powder X-ray diffraction, transmission electron microscopy, and electrochemical measurements. It was demonstrated that the NF(Aunano) composite provided high activity in the redox behavior of As(III), and was used as a potential sensing material with low Au loading for As(III) detection. An NF(Aunano)-composite-modified electrode is easy to prepare and regenerate. The dynamic range of a calibration curve from 0.1 to 12.0 μg L(-1) (from 1.3 to 160 nM), y=23.98x (in μA μM(-1))+0.42 (R(2)=0.999), showed linear behavior with a slope of 23.98 μA μM(-1). The detection limit is as low as 0.047 μg L(-1) (0.63 nM). The chelating agent ethylenediaminetetraacetate (EDTA) can selectively chelate with interfering metal ions, forming bulky complexes or bulky anions that are excluded from the NF film. The presence of EDTA effectively eliminated interference from several metal ions, particularly Cu(II) and Hg(II), which are generally considered to be major interferents in the electroanalysis of As(III). This method was applicable to As(III) analysis in three real water samples, namely groundwater, lake, and drinking waters.

  20. Portable Bioimpedance Spectroscopy device and textile electrodes for mobile monitoring applications

    NASA Astrophysics Data System (ADS)

    Beckmann, L.; Jacob, M.; Hoog Antink, C.; Cordes, A.; Pikkemaat, R.; Jungbecker, N.; Gries, T.; Leonhardt, S.

    2010-04-01

    A balanced body composition is necessary for a person's health and performance. Therefore, it is important to control the body composition continuously since complications and diseases due to dehydration often appear gradually. Based on these facts a miniaturized mobile Bioimpedance Spectroscopy device was developed that can be integrated into clothing and allows the continuous monitoring of a person's body water. The implemented system has been tested using different body models. The first measurements showed very precise and stable results. Besides the portable measurement system, textile electrodes are needed for continuous long term monitoring. Therefore, special textile electrodes were developed, tested and evaluated. The electrodes are structured in a specific way leading to a rougher surface. Such a surface improves the interface impedance and therefore optimizes the connection between electronic hardware and body. For comparison, five different structured electrodes were manufactured and tested on a special test setup that allows reproducible interface-impedance measurements using a dummy made of agar-agar to simulate the skin. It could be shown that the surface structure significantly influences the interface impedance in a positive way as compared to standard plane textile electrodes. In the future, a combination of the miniaturized BIS electronic and the structured textile electrodes could allow reproducible long term monitoring of a person's body composition.

  1. Design architecture of double spiral interdigitated electrode with back gate electrode for biosensor application

    NASA Astrophysics Data System (ADS)

    Fathil, M. F. M.; Arshad, M. K. Md.; Hashim, U.; Ruslinda, A. R.; Gopinath, Subash C. B.; M. Nuzaihan M., N.; Ayub, R. M.; Adzhri, R.; Zaki, M.; Azman, A. H.

    2016-07-01

    This paper presents the preparation method of photolithography chrome mask design used in fabrication process of double spiral interdigitated electrode with back gate biasing based biosensor. By learning the fabrication process flow of the biosensor, the chrome masks are designed through drawing using the AutoCAD software. The overall width and length of the device is optimized at 7.0 mm and 10.0 mm, respectively. Fabrication processes of the biosensor required three chrome masks, which included back gate opening, spiral IDE formation, and passivation area formation. The complete chrome masks design will be sent for chrome mask fabrication and for future use in biosensor fabrication.

  2. Novel semi-dry electrodes for brain–computer interface applications

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Li, Guangli; Chen, Jingjing; Duan, Yanwen; Zhang, Dan

    2016-08-01

    Objectives. Modern applications of brain–computer interfaces (BCIs) based on electroencephalography rely heavily on the so-called wet electrodes (e.g. Ag/AgCl electrodes) which require gel application and skin preparation to operate properly. Recently, alternative ‘dry’ electrodes have been developed to increase ease of use, but they often suffer from higher electrode–skin impedance and signal instability. In the current paper, we have proposed a novel porous ceramic-based ‘semi-dry’ electrode. The key feature of the semi-dry electrodes is that their tips can slowly and continuously release a tiny amount of electrolyte liquid to the scalp, which provides an ionic conducting path for detecting neural signals. Approach. The performance of the proposed electrode was evaluated by simultaneous recording of the wet and semi-dry electrodes pairs in five classical BCI paradigms: eyes open/closed, the motor imagery BCI, the P300 speller, the N200 speller and the steady-state visually evoked potential-based BCI. Main results. The grand-averaged temporal cross-correlation was 0.95 ± 0.07 across the subjects and the nine recording positions, and these cross-correlations were stable throughout the whole experimental protocol. In the spectral domain, the semi-dry/wet coherence was greater than 0.80 at all frequencies and greater than 0.90 at frequencies above 10 Hz, with the exception of a dip around 50 Hz (i.e. the powerline noise). More importantly, the BCI classification accuracies were also comparable between the two types of electrodes. Significance. Overall, these results indicate that the proposed semi-dry electrode can effectively capture the electrophysiological responses and is a feasible alternative to the conventional dry electrode in BCI applications.

  3. Non-invasive in situ dynamic monitoring of elastic properties of composite battery electrodes by EQCM-D.

    PubMed

    Shpigel, Netanel; Levi, Mikhael D; Sigalov, Sergey; Girshevitz, Olga; Aurbach, Doron; Daikhin, Leonid; Jäckel, Nicolas; Presser, Volker

    2015-10-12

    Reversible Li-ion intercalation into composite Li-ion battery (LIB) electrodes is often accompanied by significant dimensional electrode changes (deformation) resulting in significant deterioration of the cycling performance. Viscoelastic properties of polymeric binders affected by intercalation-induced deformation of composite LIB electrodes have never been probed in situ on operating electrochemical cells. Here, we introduce a newly developed noninvasive method, namely electrochemical quartz-crystal microbalance with dissipation monitoring (EQCM-D), for in situ monitoring of elastic properties of polymeric binders during charging of LIB electrodes. As such, we find EQCM-D as a uniquely suitable tool to track the binder's structural rigidity/softness in composite Li insertion electrodes in real-time by the characteristic increase/decrease of the dissipation factor during the charging-discharging process. The binders partially swollen in aprotic solutions demonstrate intermediate viscoelastic charge-rate-dependent behavior, revealing rigid/soft behavior at high/low charging rates, respectively. The method can be adjusted for continuous monitoring of elastic properties of the polymeric binders over the entire LIB electrodes cycling life.

  4. 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.

  5. Measurement of effective piezoelectric coefficients of PZT thin films for energy harvesting application with interdigitated electrodes.

    PubMed

    Chidambaram, Nachiappan; Mazzalai, Andrea; Muralt, Paul

    2012-08-01

    Interdigitated electrode (IDE) systems with lead zirconate titanate (PZT) thin films play an increasingly important role for two reasons: first, such a configuration generates higher voltages than parallel plate capacitor-type electrode (PPE) structures, and second, the application of an electric field leads to a compressive stress component in addition to the overall stress state, unlike a PPE structure, which results in tensile stress component. Because ceramics tend to crack at relatively moderate tensile stresses, this means that IDEs have a lower risk of cracking than PPEs. For these reasons, IDE systems are ideal for energy harvesting of vibration energy, and for actuators. Systematic investigations of PZT films with IDE systems have not yet been undertaken. In this work, we present results on the evaluation of the in-plane piezoelectric coefficients with IDE systems. Additionally, we also propose a simple and measurable figure of merit (FOM) to analyze and evaluate the relevant piezoelectric parameter for harvesting efficiency without the need to fabricate the energy harvesting device. Idealized effective coefficients e(IDE) and h(IDE) are derived, showing its composite nature with about one-third contribution of the transverse effect, and about two-thirds contribution of the longitudinal effect in the case of a PZT film deposited on a (100)-oriented silicon wafer with the in-plane electric field along one of the <011> Si directions. Randomly oriented 1-μm-thick PZT 53/47 film deposited by a sol-gel technique, was evaluated and yielded an effective coefficient e(IDE) of 15 C·m(-2). Our FOM is the product between effective e and h coefficient representing twice the electrical energy density stored in the piezoelectric film per unit strain deformation (both for IDE and PPE systems). Assuming homogeneous fields between the fingers, and neglecting the contribution from below the electrode fingers, the FOM for IDE structures with larger electrode gap is derived

  6. Fabrication of NiO thin film electrode for supercapacitor applications

    SciTech Connect

    Mali, V. V.; Navale, S. T.; Chougule, M. A.; Khuspe, G. D.; Godse, P. R.; Patil, V. B.; Pawar, S. A.

    2014-04-24

    Nanocrystalline NiO electrode is successfully electrosynthesized for supercapacitor application. The nanocrystalline NiO electrode is characterized using scanning electron microscope (SEM). Nickel oxide is a highly porous and the film surface looked smooth and composed of fine elongated particles. The supercapacitive performance of NiO electrode is tested using cyclic voltammetry (C-V) technique in 0.5M Na{sub 2}S{sub 2}O{sub 3} electrolyte within potential range of −1.2 to +1.2 V. The effect of scan rate on the capacitance of NiO electrode is studied. The highest specific capacitance of 439 Fg{sup −1} at the voltage scan rate of 50mVs{sup −1} is achieved. Additionally stability and charging–discharging of NiO electrode are studied.

  7. Application of N-doped graphene modified carbon ionic liquid electrode for direct electrochemistry of hemoglobin.

    PubMed

    Sun, Wei; Dong, Lifeng; Deng, Ying; Yu, Jianhua; Wang, Wencheng; Zhu, Qianqian

    2014-06-01

    Nitrogen-doped graphene (NG) was synthesized and used for the investigation on direct electrochemistry of hemoglobin (Hb) with a carbon ionic liquid electrode as the substrate electrode. Due to specific characteristics of NG such as excellent electrocatalytic property and large surface area, direct electron transfer of Hb was realized with enhanced electrochemical responses appearing. Electrochemical behaviors of Hb on the NG modified electrode were carefully investigated with the electrochemical parameters calculated. The Hb modified electrode exhibited excellent electrocatalytic reduction activity toward different substrates, such as trichloroacetic acid and H2O2, with wider dynamic range and lower detection limit. These findings show that NG can be used for the preparation of chemically modified electrodes with improved performance and has potential applications in electrochemical sensing.

  8. 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.

  9. Sn-0.4BPO 4 composite as a promising negative electrode for rechargeable lithium batteries

    NASA Astrophysics Data System (ADS)

    Aboulaich, Abdelmaula; Womes, Manfred; Olivier-Fourcade, Josette; Willmann, Patrick; Jumas, Jean-Claude

    2010-01-01

    The structural and textural properties of a Sn-0.4BPO 4 composite material synthesized by ex situ dispersion of β-Sn in a BPO 4 matrix were investigated by using several complementary techniques to study the global order (XRD, TGA-DSC, SEM-XEDS) and the local order (FT-IR, 119Sn Mössbauer spectroscopy and X-ray absorption spectroscopy). The results reveal that the composite material consists of three main components: an electrochemically active species "Sn", an inactive matrix "BPO 4", and an amorphous Sn(II) borophosphate which acts as a link between the two former and which improves the cohesion of the composite. The electrochemical performances of the composite material were tested in Swagelok-type cells with metallic Li as counter-electrode. It shows a high reversible capacity of about 500 mAh g -1 at a C/20 rate, and a very good stability under cycling even at very fast rates of C or C/1.3.

  10. Biomedical applications of carbon-nanotube composites.

    PubMed

    Meredith, Jay Russell; Jin, Chunming; Narayan, Roger J; Aggarwal, Ravi

    2013-01-01

    The unique physical, chemical and mechanical properties of carbon nanotubes make them attractive for a variety of biomedical applications. Carbon nanotubes have been used to modify conventional biomedical materials to enhance mechanical properties, biocompatibility, or to impart other functionalities. New multifunctional composite materials using carbon nanotubes have been developed by combining them with inorganic, polymeric or biological materials. The biomedical applications for which novel carbon nanotube composites have been investigated include antimicrobial coatings, neural implants, tissue engineering scaffolds and electrochemical biosensors. In this paper, research on development and application of carbon nanotube composites for biomedical applications has been reviewed. PMID:23277017

  11. 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.

  12. Application of electrochemically reduced graphene oxide on screen-printed ion-selective electrode.

    PubMed

    Ping, Jianfeng; Wang, Yixian; Ying, Yibin; Wu, Jian

    2012-04-01

    In this study, a novel disposable all-solid-state ion-selective electrode using graphene as the ion-to-electron transducer was developed. The graphene film was prepared on screen-printed electrode directly from the graphene oxide dispersion by a one-step electrodeposition technique. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to demonstrate the large double layer capacitance and fast charge transfer of the graphene film modified electrode. On the basis of these excellent properties, an all-solid-state calcium ion-selective electrode as the model was constructed using the calcium ion-selective membrane and graphene film modified electrode. The mechanism about the graphene promoting the ion-to-electron transformation was investigated in detail. The disposable electrode exhibited a Nernstian slope (29.1 mV/decade), low detection limit (10(-5.8) M), and fast response time (less than 10 s). With the high hydrophobic character of graphene materials, no water film was formed between the ion-selective membrane and the underlying graphene layer. Further studies revealed that the developed electrode was insensitive to light, oxygen, and redox species. The use of the disposable electrode for real sample analysis obtained satisfactory results, which made it a promising alternative in routine sensing applications.

  13. Carbon nanotube macrofilm-based nanocomposite electrodes for energy applications

    NASA Astrophysics Data System (ADS)

    Cao, Zeyuan

    Finding new electrode materials for energy conversion and storage devices have been the focus of recent research in the fields of science and engineering. Suffering from poor electronic conductivity, chemical and mechanical stability, active electrode materials are usually coupled with different carbon nanostructured materials to form nanocomposite electrodes, showing promising electrochemical performance. Among the carbon nanostructured materials, carbon nanotube (CNT) macrofilms draw great attention owing to their extraordinary properties, such as a large specific surface area, exceptionally high conductivity, porous structure, flexibility, mechanical robustness, and adhesion. They could effectively enhance the electrochemical performance of the incorporated active materials in the nanocomposites. In this dissertation, CNT macrofilm-based nanocomposites are investigated for rechargeable lithium-ion batteries, supercapacitors, and electrocatalysts of fuel cells. The progressive research developed various nanocomposites from cathode materials to anode materials followed by a general nanocomposite solution due to the unique adhesive property of the fragmented CNT macrofilms. The in-situ synthesis strategy are explored to in-situ deposit unlithiated cathode materials V2O5 and lithiated cathode materials LiMn2O4 nanocrystals in the matrix of the CNT macrofilms as nanocomposites to be paired with metallic lithium in half cells. The presence of oxygen-containing functional groups on the surface of the CNT macrofilms after purification can enhance the association with the active materials to enable the facilitated transport of solvated ions to the electrolyte/electrode interfaces and increase the diffusion kinetics, consequently enhancing the battery performance in terms of high specific capacity, rate capability, and cycling stability. It is also significant to demonstrate a reliable, low-cost, and effective route to synthesize the family of metal oxides (MxOy (M=Fe, Co

  14. Preparation and Application of Electrodes in Capacitive Deionization (CDI): a State-of-Art Review.

    PubMed

    Jia, Baoping; Zhang, Wei

    2016-12-01

    As a promising desalination technology, capacitive deionization (CDI) have shown practicality and cost-effectiveness in brackish water treatment. Developing more efficient electrode materials is the key to improving salt removal performance. This work reviewed current progress on electrode fabrication in application of CDI. Fundamental principal (e.g. EDL theory and adsorption isotherms) and process factors (e.g. pore distribution, potential, salt type and concentration) of CDI performance were presented first. It was then followed by in-depth discussion and comparison on properties and fabrication technique of different electrodes, including carbon aerogel, activated carbon, carbon nanotubes, graphene and ordered mesoporous carbon. Finally, polyaniline as conductive polymer and its potential application as CDI electrode-enhancing materials were also discussed.

  15. Preparation and Application of Electrodes in Capacitive Deionization (CDI): a State-of-Art Review.

    PubMed

    Jia, Baoping; Zhang, Wei

    2016-12-01

    As a promising desalination technology, capacitive deionization (CDI) have shown practicality and cost-effectiveness in brackish water treatment. Developing more efficient electrode materials is the key to improving salt removal performance. This work reviewed current progress on electrode fabrication in application of CDI. Fundamental principal (e.g. EDL theory and adsorption isotherms) and process factors (e.g. pore distribution, potential, salt type and concentration) of CDI performance were presented first. It was then followed by in-depth discussion and comparison on properties and fabrication technique of different electrodes, including carbon aerogel, activated carbon, carbon nanotubes, graphene and ordered mesoporous carbon. Finally, polyaniline as conductive polymer and its potential application as CDI electrode-enhancing materials were also discussed. PMID:26842797

  16. Preparation and Application of Electrodes in Capacitive Deionization (CDI): a State-of-Art Review

    NASA Astrophysics Data System (ADS)

    Jia, Baoping; Zhang, Wei

    2016-02-01

    As a promising desalination technology, capacitive deionization (CDI) have shown practicality and cost-effectiveness in brackish water treatment. Developing more efficient electrode materials is the key to improving salt removal performance. This work reviewed current progress on electrode fabrication in application of CDI. Fundamental principal (e.g. EDL theory and adsorption isotherms) and process factors (e.g. pore distribution, potential, salt type and concentration) of CDI performance were presented first. It was then followed by in-depth discussion and comparison on properties and fabrication technique of different electrodes, including carbon aerogel, activated carbon, carbon nanotubes, graphene and ordered mesoporous carbon. Finally, polyaniline as conductive polymer and its potential application as CDI electrode-enhancing materials were also discussed.

  17. 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.

  18. 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.

  19. Composite materials for biomedical applications: a review.

    PubMed

    Salernitano, E; Migliaresi, C

    2003-01-01

    The word "composite" refers to the combination, on a macroscopic scale, of two or more materials, different for composition, morphology and general physical properties. In many cases, and depending on the constituent properties, composites can be designed with a view to produce materials with properties tailored to fulfill specific chemical, physical or mechanical requirements. Therefore over the past 40 years the use of composites has progressively increased, and today composite materials have many different applications, i.e., aeronautic, automotive, naval, and so on. Consequently many composite biomaterials have recently been studied and tested for medical application. Some of them are currently commercialized for their advantages over traditional materials. Most human tissues such as bones, tendons, skin, ligaments, teeth, etc., are composites, made up of single constituents whose amount, distribution, morphology and properties determine the final behavior of the resulting tissue or organ. Man-made composites can, to some extent, be used to make prostheses able to mimic these biological tissues, to match their mechanical behavior and to restore the mechanical functions of the damaged tissue. Different types of composites that are already in use or are being investigated for various biomedical applications are presented in this paper. Specific advantages and critical issues of using composite biomaterials are also described (Journal of Applied Bio-materials & Biomechanics 2003; 1: 3-18).

  20. 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.

  1. 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.

  2. Development and standardization of porous silicon for application as a working electrode in electrochemical immunosensor

    NASA Astrophysics Data System (ADS)

    Kumari, Vinita; Mishra, Prabhash; Islam, S. S.

    2012-10-01

    Electrectrochemical immunosensors have diverse applications in areas like medical diagnostics, food industry, environmental monitoring etc. The conductive materials like Indium Tin oxide coated glass (ITO), glassy carbon, porous silicon (PS) etc. can be useful as working electrode for electrochemical immunosensor applications. But the porous silicon is particularly attractive for this application due to its modified properties like very large surface area to volume ratio, surface dependent properties (electrical and optical), photoluminescence at room temperature and biocompatibility. In this paper porous silicon is investigated for development as working electrode for label free model immunosensor based on Human IgG.

  3. 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

  4. Multi-lead ECG electrode array for clinical application of electrocardiographic inverse problem.

    PubMed

    Hintermuller, Christoph; Fischer, Gerald; Seger, Michael; Pfeifer, Bernhard; Hanser, Friedrich; Modre, Robert; Tilg, Bernhard

    2004-01-01

    Methods for noninvasive imaging of electric function of the heart might become clinical standard procedure the next years. Thus, the overall procedure has to meet clinical requirements as easy and fast application. In this study we propose a new electrode array which improves the information content in the ECG map, considering clinical constraints such as easy to apply and compatibility with routine leads. A major challenge is the development of an electrode array which yields a high information content even for a large interindividual variation in torso shape. For identifying regions of high information content we introduce the concept of a locally applied virtual electrode array. As a result of our analysis we constructed a new electrode array consisting of two L-shaped regular spaced parts and compared it to the electrode array we use for clinical studies upon activation time imaging. We assume that one side effect caused by the regular shape and spacing of the new array be that the reconstruction of electrodes placed on the patients back is simplified. It may be sufficient to record a few characteristic electrode positions and merge them with a model of the posterior array.

  5. Composite materials for space applications

    NASA Technical Reports Server (NTRS)

    Rawal, Suraj P.; Misra, Mohan S.; Wendt, Robert G.

    1990-01-01

    The objectives of the program were to: generate mechanical, thermal, and physical property test data for as-fabricated advanced materials; design and fabricate an accelerated thermal cycling chamber; and determine the effect of thermal cycling on thermomechanical properties and dimensional stability of composites. In the current program, extensive mechanical and thermophysical property tests of various organic matrix, metal matrix, glass matrix, and carbon-carbon composites were conducted, and a reliable database was constructed for spacecraft material selection. Material property results for the majority of the as-fabricated composites were consistent with the predicted values, providing a measure of consolidation integrity attained during fabrication. To determine the effect of thermal cycling on mechanical properties, microcracking, and thermal expansion behavior, approximately 500 composite specimens were exposed to 10,000 cycles between -150 and +150 F. These specimens were placed in a large (18 cu ft work space) thermal cycling chamber that was specially designed and fabricated to simulate one year low earth orbital (LEO) thermal cycling in 20 days. With this rate of thermal cycling, this is the largest thermal cycling unit in the country. Material property measurements of the thermal cycled organic matrix composite laminate specimens exhibited less than 24 percent decrease in strength, whereas, the remaining materials exhibited less than 8 percent decrease in strength. The thermal expansion response of each of the thermal cycled specimens revealed significant reduction in hysteresis and residual strain, and the average CTE values were close to the predicted values.

  6. 21 CFR 884.2675 - Fetal scalp circular (spiral) electrode and applicator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... applicator. 884.2675 Section 884.2675 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... Gynecological Monitoring Devices § 884.2675 Fetal scalp circular (spiral) electrode and applicator. (a... monitoring device by a shallow subcutaneous puncture of fetal scalp tissue with a curved needle or...

  7. Selective Electrochemical Detection of Ciprofloxacin with a Porous Nafion/Multiwalled Carbon Nanotube Composite Film Electrode.

    PubMed

    Gayen, Pralay; Chaplin, Brian P

    2016-01-27

    This study focuses on the development of electrochemical sensors for the detection of Ciprofloxacin (CFX) in natural waters and wastewater effluents. The sensors are prepared by depositing a layer of multiwalled carbon nanotubes (MWCNTs) dispersed in a porous Nafion film on to a boron-doped diamond (BDD) electrode substrate. The porous-Nafion-MWCNT/BDD electrode enhanced detection of CFX due to selective adsorption, which was accomplished by a combination of electrostatic attraction at -SO3(-) sites in the porous Nafion film and the formation of charge assisted hydrogen bonding between CFX and -COOH MWCNT surface functional groups. By contrast, the bare BDD electrode did not show any activity for CFX oxidation. The sensors were selective for CFX detection in the presence of other antibiotics (i.e., amoxicillin) and other nontarget water constituents (i.e., Cl(-), Ca(2+), humic acid, sodium dodecylbenzenesulfonate, salicylic acid, 4-aminobenzoic acid, and 4-hydroxybenzoic acid). A limit of detection of 5 nM (S/N = 5.04 ± 0.26) in a 0.1 M KH2PO4 supporting electrolyte (pH = 4.5) was obtained using differential pulse voltammetry. The linear dynamic ranges with respect to CFX concentration were 0.005-0.05 μM and 0.05-10 μM, and the sensitivities were 41 ± 5.2 μA μM(-1) and 2.1 ± 0.22 μA μM(-1), respectively. Sensor fouling was observed at high concentrations of some organic compounds such as 1 mM 4-aminobenzoic acid and 4-hydroxybenzoic acid. However, a short cathodic treatment fully restores sensor response. The results indicate that these sensors have application in detecting CFX in natural waters and wastewater effluents. PMID:26711553

  8. Selective Electrochemical Detection of Ciprofloxacin with a Porous Nafion/Multiwalled Carbon Nanotube Composite Film Electrode.

    PubMed

    Gayen, Pralay; Chaplin, Brian P

    2016-01-27

    This study focuses on the development of electrochemical sensors for the detection of Ciprofloxacin (CFX) in natural waters and wastewater effluents. The sensors are prepared by depositing a layer of multiwalled carbon nanotubes (MWCNTs) dispersed in a porous Nafion film on to a boron-doped diamond (BDD) electrode substrate. The porous-Nafion-MWCNT/BDD electrode enhanced detection of CFX due to selective adsorption, which was accomplished by a combination of electrostatic attraction at -SO3(-) sites in the porous Nafion film and the formation of charge assisted hydrogen bonding between CFX and -COOH MWCNT surface functional groups. By contrast, the bare BDD electrode did not show any activity for CFX oxidation. The sensors were selective for CFX detection in the presence of other antibiotics (i.e., amoxicillin) and other nontarget water constituents (i.e., Cl(-), Ca(2+), humic acid, sodium dodecylbenzenesulfonate, salicylic acid, 4-aminobenzoic acid, and 4-hydroxybenzoic acid). A limit of detection of 5 nM (S/N = 5.04 ± 0.26) in a 0.1 M KH2PO4 supporting electrolyte (pH = 4.5) was obtained using differential pulse voltammetry. The linear dynamic ranges with respect to CFX concentration were 0.005-0.05 μM and 0.05-10 μM, and the sensitivities were 41 ± 5.2 μA μM(-1) and 2.1 ± 0.22 μA μM(-1), respectively. Sensor fouling was observed at high concentrations of some organic compounds such as 1 mM 4-aminobenzoic acid and 4-hydroxybenzoic acid. However, a short cathodic treatment fully restores sensor response. The results indicate that these sensors have application in detecting CFX in natural waters and wastewater effluents.

  9. Application of mesoporous carbon to counter electrode for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Guiqiang; Xing, Wei; Zhuo, Shuping

    The mesoporous carbons were prepared by the carbonation of the triblock copolymer F127/phloroglucinol-formaldehyde composite self-assembled in an acid medium and employed as the catalyst for triiodide reduction in dye-sensitized solar cells (DSCs). The characteristics of mesoporous carbon were analyzed by scanning electron microscopy, transmission electron microscopy, N 2 sorption measurement and X-ray diffraction. The mesoporous carbon with low crystallinity exhibited Brunauer-Emmett-Teller surface area of 400 m 2 g -1, pore diameter of 6.8 nm and pore volume of 0.63 cm 3 g -1. The photovoltaic performances of DSCs with mesoporous carbon counter electrode were improved by increasing the carbon loading on counter electrode due to the charge-transfer resistance of mesoporous carbon counter electrode decreasing with the increase of the carbon loading. However, further carbon loading increase has no obvious effect on the photovoltaic performance of DSCs with carbon electrode when carbon loading exceeds 300 μg cm -2. The overall conversion efficiency of 6.18% was obtained by DSCs composed of mesoporous carbon counter electrode with the carbon loading of 339 μg cm -2. This value is comparable to that of DSCs with conventional platinum counter electrode.

  10. All-solid-state electrochemical capacitors using MnO2 electrode/SiO2-Nafion electrolyte composite prepared by the sol-gel process

    NASA Astrophysics Data System (ADS)

    Shimamoto, Kazushi; Tadanaga, Kiyoharu; Tatsumisago, Masahiro

    2014-02-01

    Electrode-electrolyte composites of MnO2 active material, acetylene black (AB), and SiO2-Nafion solid electrolyte were prepared using the sol-gel process to form good solid-solid interfaces. The composites were obtained by the addition of MnO2 and AB into a sol of hydrolyzed tetraethoxysilane with Nafion, and successive solidification of the precursor sol. Scanning electron microscope and energy dispersive X-ray spectroscopy measurements show that good solid-solid interface is formed between electrodes and solid electrolytes in the composites. All-solid-state hybrid capacitors were fabricated using the composites or the hand-grinding mixture of MnO2, AB and SiO2-Nafion powder as positive electrodes, activated carbon powder as a negative electrode, and phosphosilicate gel as a solid electrolyte. The all-solid-state hybrid capacitors using the composites exhibit larger capacitances and better rate performance than the capacitors using the electrode prepared by hand-mixing of powders. Specific discharge capacitances of the capacitor with the composite are 85 F g-1 for the one with the composite electrode and 48 F g-1 for the one with the hand-mixed electrode, at 1 mA cm-2. Moreover, the all-solid-state capacitors using the composite electrode can be operated at temperatures between -30 °C and 60 °C.

  11. 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...

  12. Application of composite insulators to transmission lines

    SciTech Connect

    Cherney, E.A.; Brown, R.L.; Karady, G.; Nicholls, J.L.; Orbeck, T.; Pargamin, L.

    1983-05-01

    The paper provides guidelines for the application of composite insulators to transmission lines. These guidelines are based on utility field experiences, results of research laboratory tests and manufacturers' recommendations. Discussed are interchangeability with porcelain and glass insulators, application in contaminated environments, material ageing, insulator icing, the use of grease, resistance to vandalism, temperature extremes, and the need for grading rings. Clarification is provided on the mechanical rating of composite insulators because there is not yet general agreement by various industry groups.

  13. Novel electrode-elastomer combinations for improved performance and application of dielectric elastomers

    NASA Astrophysics Data System (ADS)

    Yuan, Wei

    Dielectric elastomers are the most promising technology for mimicking human muscles in terms of strain, stress, and work density, etc. Actuators have been fabricated based on different design concepts and configurations for applications in robotics, prosthetic devices, medical implants, pumps, and valves. However, to date these actuators have experienced high rates of failure caused by electrical shorting of the compliant electrodes through the elastomer film during electrical breakdown, which has prevented their practical application. In this thesis, single walled carbon nanotube (SWNT) thin films were employed as compliant electrodes for dielectric elastomers to reduce the rate of failure. Thanks to the high aspect ratio of the SWNTs, the electrodes maintain substantial conductance at high biaxial strains. 3M VHB acrylics can be actuated up to 200% area strain with SWNT electrodes, this matches the performance of actuators with carbon grease electrodes. During uni-directional stretching, SWNT electrodes can maintain surface conductivity up to 700% linear strain. SWNT electrodes can experience a self-clearing process under high voltage discharging and electrically isolate the electrodes around the breakdown sites when breakdown events happen. With conventional dielectric elastomer electrode materials such as carbon grease and carbon black, a single breakdown event results in a permanent loss in the actuator's functionality. In contrast, for SWNT electrodes, the SWNTs around the breakdown site will be degraded and become non-conductive. The non-conductive area expands outward until the high voltage discharging stops. As such, the opposing electrodes are prevented from coming into contact with each other and forming an electrical short and the breakdown site is electrically isolated from the remainder of the active area. Despite the existence of the breakdown sites, the dielectric elastomer will resume its functionality and avoid permanent failure. Thus, dielectric

  14. Selective growth of ZnO nanorods on microgap electrodes and their applications in UV sensors

    PubMed Central

    2014-01-01

    Selective area growth of ZnO nanorods is accomplished on microgap electrodes (spacing of 6 μm) by using a facile wet chemical etching process. The growth of ZnO nanorods on a selected area of microgap electrode is carried out by hydrothermal synthesis forming nanorod bridge between two electrodes. This is an attractive, genuine, direct, and highly reproducible technique to grow nanowire/nanorod onto the electrodes on selected area. The ZnO nanorods were grown at 90°C on the pre-patterned electrode system without destroying the electrode surface structure interface and geometry. The ZnO nanorods were tested for their application in ultraviolet (UV) sensors. The photocurrent-to-dark (Iph/Id) ratio was 3.11. At an applied voltage of 5 V, the response and recovery time was 72 and 110 s, respectively, and the response reached 2 A/W. The deposited ZnO nanorods exhibited a UV photoresponse that is promising for future cost-effective and low-power electronic UV-sensing applications. PMID:24423232

  15. ZnO:H indium-free transparent conductive electrodes for active-matrix display applications

    NASA Astrophysics Data System (ADS)

    Chen, Shuming; Wang, Sisi

    2014-12-01

    Transparent conductive electrodes based on hydrogen (H)-doped zinc oxide (ZnO) have been proposed for active-matrix (AM) display applications. When fabricated with optimal H plasma power and optimal plasma treatment time, the resulting ZnO:H films exhibit low sheet resistance of 200 Ω/◻ and high average transmission of 85% at a film thickness of 150 nm. The demonstrated transparent conductive ZnO:H films can potentially replace indium-tin-oxide and serve as pixel electrodes for organic light-emitting diodes as well as source/drain electrodes for ZnO-based thin-film transistors. Use of the proposed ZnO:H electrodes means that two photomask stages can be removed from the fabrication process flow for ZnO-based AM backplanes.

  16. ZnO:H indium-free transparent conductive electrodes for active-matrix display applications

    SciTech Connect

    Chen, Shuming Wang, Sisi

    2014-12-01

    Transparent conductive electrodes based on hydrogen (H)-doped zinc oxide (ZnO) have been proposed for active-matrix (AM) display applications. When fabricated with optimal H plasma power and optimal plasma treatment time, the resulting ZnO:H films exhibit low sheet resistance of 200 Ω/◻ and high average transmission of 85% at a film thickness of 150 nm. The demonstrated transparent conductive ZnO:H films can potentially replace indium-tin-oxide and serve as pixel electrodes for organic light-emitting diodes as well as source/drain electrodes for ZnO-based thin-film transistors. Use of the proposed ZnO:H electrodes means that two photomask stages can be removed from the fabrication process flow for ZnO-based AM backplanes.

  17. Simple fabrication of porous gold-film electrodes and their electroanalytical applications.

    PubMed

    Hyun, Myeounghee; Choi, Suhee; Kim, Jongwon

    2010-01-01

    A simple strategy to fabricate porous three-dimensional gold-film electrodes using gold-coated microspheres (AuMS) is presented. The AuMS deposited on gold (AuMS/Au) are electrically interconnected, and show unique electrochemical properties indicating porous surface structures. The AuMS/Au electrodes exhibit electrocatalytic activities for oxygen reduction and peroxide oxidation, which indicates that the apparent macroporous structures also retain porous regions with nanometer-scale dimensions. The porous structures on AuMS/Au electrodes also provide a selective voltammetric response for glucose against ascorbic acid due to the different electron-transfer kinetics. Since AuMS/Au electrodes are simple to prepare compared with previously suggested systems, the present system could offer potential in electroanalytical applications as new gold-based substrates for further modifications of surfaces.

  18. Bristle-sensors--low-cost flexible passive dry EEG electrodes for neurofeedback and BCI applications.

    PubMed

    Grozea, Cristian; Voinescu, Catalin D; Fazli, Siamac

    2011-04-01

    In this paper, we present a new, low-cost dry electrode for EEG that is made of flexible metal-coated polymer bristles. We examine various standard EEG paradigms, such as capturing occipital alpha rhythms, testing for event-related potentials in an auditory oddball paradigm and performing a sensory motor rhythm-based event-related (de-) synchronization paradigm to validate the performance of the novel electrodes in terms of signal quality. Our findings suggest that the dry electrodes that we developed result in high-quality EEG recordings and are thus suitable for a wide range of EEG studies and BCI applications. Furthermore, due to the flexibility of the novel electrodes, greater comfort is achieved in some subjects, this being essential for long-term use.

  19. Bristle-sensors—low-cost flexible passive dry EEG electrodes for neurofeedback and BCI applications

    NASA Astrophysics Data System (ADS)

    Grozea, Cristian; Voinescu, Catalin D.; Fazli, Siamac

    2011-04-01

    In this paper, we present a new, low-cost dry electrode for EEG that is made of flexible metal-coated polymer bristles. We examine various standard EEG paradigms, such as capturing occipital alpha rhythms, testing for event-related potentials in an auditory oddball paradigm and performing a sensory motor rhythm-based event-related (de-) synchronization paradigm to validate the performance of the novel electrodes in terms of signal quality. Our findings suggest that the dry electrodes that we developed result in high-quality EEG recordings and are thus suitable for a wide range of EEG studies and BCI applications. Furthermore, due to the flexibility of the novel electrodes, greater comfort is achieved in some subjects, this being essential for long-term use.

  20. Carbothermal synthesis of Sn-based composites as negative electrode for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Mouyane, M.; Ruiz, J.-M.; Artus, M.; Cassaignon, S.; Jolivet, J.-P.; Caillon, G.; Jordy, C.; Driesen, K.; Scoyer, J.; Stievano, L.; Olivier-Fourcade, J.; Jumas, J.-C.

    The composite [Sn-BPO 4/ xC] to be used as negative electrode material for the storage of electrochemical energy was obtained by dispersing electroactive tin species onto a BPO 4 buffer matrix by carbothermal reduction of a mixture of SnO 2 and nanosized BPO 4. This composite material was thoroughly characterized by X-ray diffraction, Scanning Electron Microscopy, 119Sn Mössbauer spectroscopy and Raman spectroscopy. The electrochemical tests of this new material highlight its very interesting electrochemical properties, i.e., a discharge capacity of 850 mAh g -1 for the first cycle and reversible capacity around 585 mAh g -1 at C/5 rate. These electrochemical performances are attributed to the very high dispersion and stabilisation of tin metal particles onto the BPO 4 matrix. The irreversible capacity observed for the first charge/discharge cycle is due the reduction of interfacial Sn II species and to the passivation of the anode surface by liquid electrolyte decomposition (formation of the SEI layer).

  1. Outgassing considerations for composites in space applications

    NASA Technical Reports Server (NTRS)

    Arsenovic, Petar; Chu, Huai-Pu

    1994-01-01

    Composites have been increasingly used in the construction of spacecraft. However, unlike metals, composites must be used with particular discretion in space applications because of their outgassing properties. For example, the outgas materials may cause serious contamination problems and affect the performance of delicate instruments. This paper presents an overview of the testing procedure and acceptance criteria for outgassing selection of spacecraft materials. Since composites can contain and absorb moisture which will outgas in space as water vapor, the test results of moisture absorption and desorption of a composite material are discussed also.

  2. The preparation and performance of calcium carbide-derived carbon/polyaniline composite electrode material for supercapacitors

    NASA Astrophysics Data System (ADS)

    Zheng, Liping; Wang, Ying; Wang, Xianyou; Li, Na; An, Hongfang; Chen, Huajie; Guo, Jia

    Calcium carbide (CaC 2)-derived carbon (CCDC)/polyaniline (PANI) composite materials are prepared by in situ chemical oxidation polymerization of an aniline solution containing well-dispersed CCDC. The structure and morphology of CCDC/PANI composite are characterized by Fourier infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscopy (TEM) and N 2 sorption isotherms. It has been found that PANI was uniformly deposited on the surface and the inner pores of CCDC. The supercapacitive behaviors of the CCDC/PANI composite materials are investigated with cyclic voltammetry (CV), galvanostatic charge/discharge and cycle life measurements. The results show that the CCDC/PANI composite electrodes have higher specific capacitances than the as grown CCDC electrodes and higher stability than the conducting polymers. The capacitance of CCDC/PANI composite electrode is as high as 713.4 F g -1 measured by cyclic voltammetry at 1 mV s -1. Besides, the capacitance retention of coin supercapacitor remained 80.1% after 1000 cycles.

  3. 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.

  4. 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. PMID:26720592

  5. Electrochemical dealloying using pulsed voltage waveforms and its application for supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Zhan, Yawen; Bian, Haidong; Li, Zhe; Tsang, Chun-Kwan; Lee, Chris; Cheng, Hua; Shu, Shiwei; Li, Yang Yang; Lu, Jian

    2014-07-01

    Dealloying is an important industrial technique for generating nanoporous metallic structures by selectively leaching out the more reactive metal component from an alloy material. A constant voltage is often applied to facilitate the dealloying process. Here we report the first study on dealloying with the application of a voltage waveform-specifically, pulsed voltage waveforms are applied for dealloying Ni-Cu alloys. It is found that pulsed dealloying voltage waveforms can exert a strong impact on the dealloying process by 1) significantly lowering the compositional threshold of the more reactive metal component for the dealloying reaction to take place, 2) more thoroughly removing the more reactive metal component and thus producing a porous metal of higher purity and higher porosity (volume fraction of voids), and 3) greatly affecting the morphology of the generated porous metal structure (e.g., leading to significantly thinner ligaments). The nanoporous metallic materials obtained by the pulsed voltage waveform enable supercapacitor electrodes of significantly better performance than the counterpart dealloyed with a constant voltage.

  6. Study on the applicability of polytetrafluoroethylene-silver composite thin films as sensor material

    NASA Astrophysics Data System (ADS)

    Smausz, Tomi; Kecskeméti, Gabriella; Csizmadia, Tamás; Benedek, Ferenc; Hopp, Béla

    2013-08-01

    A study on applicability of conductive high specific surface PTFE/Ag composite layers as active electrodes of a non-enzymatic cholesterol sensor is presented. The composite layers were prepared on one of the two neighboring electrode of a printed circuit board by pulsed laser deposition technique where targets composed of silver and PTFE were ablated by an ArF excimer laser. Cholesterol was dissolved in 0.1 M NaOH in different concentrations in 0-5 mM range. A drop of cholesterol covered the two electrodes and a constant current of 10 μA was forced through the sample while the voltage between the electrodes was measured by means of a high resolution A/D converter with 1 kHz sampling rate for 5 s periods. Instead of the time-averaged signal monitoring we applied the Fluctuation-Enhanced Sensing (FES) method which is based on the analysis of the stochastic component of the signal. The power spectral density of the fluctuation was found to be dependent on the cholesterol concentration of the samples. Principal Component Analysis method was used for quantifying the difference between the recorded spectra. A tendentious variation of the spectral properties as the function of the cholesterol concentration was observed. The results indicate that the FES technique combined with high specific surface composite electrodes may be a useful tool for cholesterol detection.

  7. Application of Carbon Nanotubes as Working Electrodes for Cyclic Voltammetry & Impedance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Barrios, Joseph; Cabral, Murilo; Carrilho, Emanuel; Garcia, Carlos; Ayon, Arturo

    2010-10-01

    Research conducted focuses on applications of Multi Walled Carbon Nanotubes (MWCNTs) serving as working electrodes for cyclic voltammetry (CV) and impedance spectroscopy. Expectations of increased electrochemical properties of the working electrodes were confirmed and the analysis of CNTs electrical properties was obtained. Conditions for the MWCNTs are as follows: after acidic functionalization, MWCNTs bonded with N-hydroxysuccinimide, and MWCNTs bonded with the AChE protein. Iron cyanide was chosen as the optimal analyte solution. Concentration of MWCNTs on the working electrode was also investigated. With CV an increase in capacitance, sensitivity, and sensibility was noticed. When compared to the unmodified graphite carbon electrode the modified electrode yielded lower resistivity, and higher capacitance. When compared to NHS and the AChE protein, the functionalized CNTs yielded a higher capacitance, increased sensitivity and sensibility with decrease in surface roughness. Through FTIR analysis the presence of increased carboxyl groups, enzymes, and N-hydroxysuccinimide on the walls of the MWCNTs was confirmed. In conclusion the addition of MWCNTs improved the electrodes sensitivity and sensibility for CV.

  8. Fabrication of highly porous platinum electrodes for micro-scale applications by pulsed electrodeposition and dealloying

    NASA Astrophysics Data System (ADS)

    Köhler, Christian; Kloke, Arne; Drzyzga, Anna; Zengerle, Roland; Kerzenmacher, Sven

    2013-11-01

    We present the implementation and optimization of a novel electrodeposition method for the fabrication of highly porous platinum electrodes. It is based on the co-deposition of platinum and copper and the selective dealloying of copper in a pulsed manner. The new process yields mechanically stable platinum electrodes with roughness factors of up to RF = 6500 ± 700, compared to the state-of-the-art cyclic electrodeposition method this corresponds to an improvement in RF by 111%. Furthermore the time demand for fabrication is reduced by 59%, whereas the platinum utilization is increased by 53%. The method is particularly advantageous for applications such as micro fuel cells since it enables the precise deposition of catalytically active electrodes on micro-structured conductive areas. In this context the novel platinum electrodes show higher current densities for the oxidation of formic acid and glucose than state-of-the-art electrodes. In terms of methanol oxidation their catalytic activity is comparable to commercial direct methanol fuel cell (DMFC) electrodes, fabricated from Pt-Ru nanoparticles dispersed on carbon black.

  9. Enhanced capacitance of composite TiO2 nanotube/boron-doped diamond electrodes studied by impedance spectroscopy.

    PubMed

    Siuzdak, K; Bogdanowicz, R; Sawczak, M; Sobaszek, M

    2015-01-14

    We report on novel composite nanostructures based on boron-doped diamond thin films grown on top of TiO2 nanotubes. The nanostructures made of BDD-modified titania nanotubes showed an increase in activity and performance when used as electrodes in electrochemical environments. The BDD thin films (∼200-500 nm) were deposited using microwave plasma assisted chemical vapor deposition (MW PA CVD) onto anodically fabricated TiO2 nanotube arrays. The influence of boron-doping level, methane admixture and growth time on the performance of the Ti/TiO2/BDD electrode was studied in detail. Scanning electron microscopy (SEM) was applied to investigate the surface morphology and grain size distribution. Moreover, the chemical composition of TiO2/BDD electrodes was investigated by means of micro-Raman spectroscopy. The composite electrodes TiO2/BDD are characterized by a significantly higher capacitive current compared to BDD films deposited directly onto a Ti substrate. The novel composite electrode of TiO2 nanotube arrays overgrown by boron-doped diamond (BDD) immersed in 0.1 M NaNO3 can deliver a specific capacitance of 2.10, 4.79, and 7.46 mF cm(-2) at a scan rate of 10 mV s(-1) for a [B]/[C] ratio of 2k, 5k and 10k, respectively. The substantial improvement of electrochemical performance and the excellent rate capability could be attributed to the synergistic effect of TiO2 treatment in CH4 : H2 plasma and the high electrical conductivity of BDD layers. The analysis of electrochemical impedance spectra using an electric equivalent circuit allowed us to determine the surface area on the basis of the value of constant phase element.

  10. Enhanced capacitance of composite TiO2 nanotube/boron-doped diamond electrodes studied by impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Siuzdak, K.; Bogdanowicz, R.; Sawczak, M.; Sobaszek, M.

    2014-12-01

    We report on novel composite nanostructures based on boron-doped diamond thin films grown on top of TiO2 nanotubes. The nanostructures made of BDD-modified titania nanotubes showed an increase in activity and performance when used as electrodes in electrochemical environments. The BDD thin films (~200-500 nm) were deposited using microwave plasma assisted chemical vapor deposition (MW PA CVD) onto anodically fabricated TiO2 nanotube arrays. The influence of boron-doping level, methane admixture and growth time on the performance of the Ti/TiO2/BDD electrode was studied in detail. Scanning electron microscopy (SEM) was applied to investigate the surface morphology and grain size distribution. Moreover, the chemical composition of TiO2/BDD electrodes was investigated by means of micro-Raman spectroscopy. The composite electrodes TiO2/BDD are characterized by a significantly higher capacitive current compared to BDD films deposited directly onto a Ti substrate. The novel composite electrode of TiO2 nanotube arrays overgrown by boron-doped diamond (BDD) immersed in 0.1 M NaNO3 can deliver a specific capacitance of 2.10, 4.79, and 7.46 mF cm-2 at a scan rate of 10 mV s-1 for a [B]/[C] ratio of 2k, 5k and 10k, respectively. The substantial improvement of electrochemical performance and the excellent rate capability could be attributed to the synergistic effect of TiO2 treatment in CH4 : H2 plasma and the high electrical conductivity of BDD layers. The analysis of electrochemical impedance spectra using an electric equivalent circuit allowed us to determine the surface area on the basis of the value of constant phase element.

  11. High-energy-density, all-solid-state microsupercapacitors with three-dimensional interdigital electrodes of carbon/polymer electrolyte composite

    NASA Astrophysics Data System (ADS)

    Pu, Juan; Wang, Xiaohong; Zhang, Tianyi; Li, Siwei; Liu, Jinghe; Komvopoulos, Kyriakos

    2016-01-01

    Novel all-solid-state microsupercapacitors (MSCs) with three-dimensional (3D) electrodes consisting of active materials (i.e., graphene or activated carbon (AC) particles) and polymer electrolyte (PE) designed for high-energy-density storage applications were fabricated and tested in this work. The incorporation of PE in the electrode material enhances the accessibility of electrolyte ions to the surface of active materials and decreases the ion diffusion path during electrochemical charge/discharge. For a scan rate of 5 mV s-1, the MSCs with graphene/PE and AC/PE composite electrodes demonstrate a very high areal capacitance of 95 and 134 mF cm-2, respectively, comparable to that of 3D MSCs with liquid electrolyte. In addition, the graphene/PE MSCs show a ˜70% increase in specific capacitance after 10 000 charge/discharge cycles, attributed to an electro-activation process resulting from ion intercalation between the graphene nanosheets. The AC/PE MSCs also demonstrate excellent stability. The results of this study illustrate the potential of the present 3D MSCs for various high-density solid-state energy storage applications.

  12. Organic-Inorganic Composites Toward Biomaterial Application.

    PubMed

    Miyazaki, Toshiki; Sugawara-Narutaki, Ayae; Ohtsuki, Chikara

    2015-01-01

    Bioactive ceramics are known to exhibit specific biological affinities and are able to show direct integration with surrounding bone when implanted in bony defects. However, their inadequate mechanical properties, such as low fracture toughness and high Young's modulus in comparison to natural bone, limit their clinical application. Bone is a kind of organic-inorganic composite where apatite nanocrystals are precipitated onto collagen fibre networks. Thus, one way to address these problems is to mimic the natural composition of bone by using bioactive ceramics via material designs based on organic-inorganic composites. In this chapter, the current research on the development of the various organic-inorganic composites designed for biomaterial applications has been reviewed. Various compounds such as calcium phosphate, calcium sulphate and calcium carbonate can be used for the inorganic phases to design composites with the desired mechanical and biological properties of bone. Not only classical mechanical mixing but also coating of the inorganic phase in aqueous conditions is available for the fabrication of such composites. Organic modifications using various polymers enable the control of the crystalline structure of the calcium carbonate in the composites. These approaches on the fabrication of organic-inorganic composites provide important options for biomedical materials with novel functions.

  13. Composite Development and Applications for RLV Tankage

    NASA Technical Reports Server (NTRS)

    Wright, Richard J.; Achary, David C.; McBain, Michael C.

    2003-01-01

    The development of polymer composite cryogenic tanks is a critical step in creating the next generation of launch vehicles. Future launch vehicles need to minimize the gross liftoff weight (GLOW), which is possible due to the 28%-41% reduction in weight that composite materials can provide over current aluminum technology. The development of composite cryogenic tanks, feedlines, and unpressurized structures are key enabling technologies for performance and cost enhancements for Reusable Launch Vehicles (RLVs). The technology development of composite tanks has provided direct and applicable data for feedlines, unpressurized structures, material compatibility, and cryogenic fluid containment for highly loaded complex structures and interfaces. All three types of structure have similar material systems, processing parameters, scaling issues, analysis methodologies, NDE development, damage tolerance, and repair scenarios. Composite cryogenic tankage is the most complex of the 3 areas and provides the largest breakthrough in technology. A building block approach has been employed to bring this family of difficult technologies to maturity. This approach has built up composite materials, processes, design, analysis and test methods technology through a series of composite test programs beginning with the NASP program to meet aggressive performance goals for reusable launch vehicles. In this paper, the development and application of advanced composites for RLV use is described.

  14. Organic-Inorganic Composites Toward Biomaterial Application.

    PubMed

    Miyazaki, Toshiki; Sugawara-Narutaki, Ayae; Ohtsuki, Chikara

    2015-01-01

    Bioactive ceramics are known to exhibit specific biological affinities and are able to show direct integration with surrounding bone when implanted in bony defects. However, their inadequate mechanical properties, such as low fracture toughness and high Young's modulus in comparison to natural bone, limit their clinical application. Bone is a kind of organic-inorganic composite where apatite nanocrystals are precipitated onto collagen fibre networks. Thus, one way to address these problems is to mimic the natural composition of bone by using bioactive ceramics via material designs based on organic-inorganic composites. In this chapter, the current research on the development of the various organic-inorganic composites designed for biomaterial applications has been reviewed. Various compounds such as calcium phosphate, calcium sulphate and calcium carbonate can be used for the inorganic phases to design composites with the desired mechanical and biological properties of bone. Not only classical mechanical mixing but also coating of the inorganic phase in aqueous conditions is available for the fabrication of such composites. Organic modifications using various polymers enable the control of the crystalline structure of the calcium carbonate in the composites. These approaches on the fabrication of organic-inorganic composites provide important options for biomedical materials with novel functions. PMID:26201274

  15. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

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

    PubMed

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

    2014-05-20

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

  18. Composite material application for liquid rocket engines

    NASA Technical Reports Server (NTRS)

    Heubner, S. W.

    1982-01-01

    With increasing emphasis on improving engine thrust-to-weight ratios to provide improved payload capabilities, weight reductions achievable by the use of composites have become attractive. Of primary significance is the weight reduction offered by composites, although high temperature properties and cost reduction were also considered. The potential for application of composites to components of Earth-to-orbit hydrocarbon engines and orbit-to-orbit LOX/H2 engines was assessed. The components most likely to benefit from the application of composites were identified, as were the critical technology areas where developed would be required. Recommendations were made and a program outlined for the design, fabrication, and demonstration of specific engine components.

  19. Automotive applications for advanced composite materials

    NASA Technical Reports Server (NTRS)

    Deutsch, G. C.

    1978-01-01

    A description is presented of nonaerospace applications for advanced composite materials with special emphasis on the automotive applications. The automotive industry has to satisfy exacting requirements to reduce the average fuel consumption of cars. A feasible approach to accomplish this involves the development of composites cars with a total weight of 2400 pounds and a fuel consumption of 33 miles per gallon. In connection with this possibility, the automotive companies have started to look seriously at composite materials. The aerospace industry has over the past decade accumulated a considerable data base on composite materials and this is being made available to the nonaerospace sector. However, the automotive companies will place prime emphasis on low cost resins which lend themselves to rapid fabrication techniques.

  20. New textile composite materials development, production, application

    NASA Technical Reports Server (NTRS)

    Mikhailov, Petr Y.

    1993-01-01

    New textile composite materials development, production, and application are discussed. Topics covered include: super-high-strength, super-high-modulus fibers, filaments, and materials manufactured on their basis; heat-resistant and nonflammable fibers, filaments, and textile fabrics; fibers and textile fabrics based on fluorocarbon poylmers; antifriction textile fabrics based on polyfen filaments; development of new types of textile combines and composite materials; and carbon filament-based fabrics.

  1. Improving sensitivity of photorefractive polymer composites for holographic display applications

    NASA Astrophysics Data System (ADS)

    Christenson, Cory W.

    This work presents recent progress in the area of organic photorefractive polymer composites. These materials have been previously shown to be a suitable medium for dynamic holographic displays, with multiple colors and single frame writing times on the order of seconds. However, these materials still require large electric fields and high intensity lasers to function effectively. Recent advancements in improving these areas are discussed, including a review of the history and state-of-the-art in photorefractive polymer composites. The addition of electron traps via low loading of the electron-transporting molecule Alq3 is shown to dramatically improve the diffraction efficiency and reduce the required field. The grating formation also proceeds faster by more than one order of magnitude, leading to an increase in sensitivity by a factor of 3. The dynamics of these materials also show evidence of competing gratings indicative of bipolar charge transport and trapping. The addition of an amorphous polycarbonate (APC) buffer layer is reported to have a similar effect on the steady-state diffraction efficiency, and the further doping with a fullerene derivative (PCBM) allows a 3x increase in the efficiency in the reflection geometry, which is normally poor due to the small grating spacing. These composites reveal the fundamental limits of the reflection geometry, based on the physics of high frequency gratings. A reversal in the direction and increase in the magnitude of the two-beam coupling energy transfer is also observed. The use of interdigitated coplanar electrodes, instead of the standard uniform electrodes in a parallel-plate geometry, is shown to result in large diffraction efficiency with symmetric writing beams due to the increased projection field. The efficiency is similar to that achieved in the standard samples with large slant angles and much better than those geometries typically used in applications, with the benefit that the writing beams do not have

  2. 21 CFR 884.2685 - Fetal scalp clip electrode and applicator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ....2685 Section 884.2685 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Monitoring Devices § 884.2685 Fetal scalp clip electrode and applicator. (a) Identification. A fetal scalp... and an external monitoring device by means of pinching skin tissue with a nonreusable clip....

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

    DOE PAGES

    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 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

  4. 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.

  5. Prediction of transmittance spectra for transparent composite electrodes with ultra-thin metal layers

    NASA Astrophysics Data System (ADS)

    Zhao, Zhao; Khorasani, Arash Elhami; Theodore, N. D.; Dhar, A.; Alford, T. L.

    2015-11-01

    Recent interest in indium-free transparent composite-electrodes (TCEs) has motivated theoretical and experimental efforts to better understand and enhance their electrical and optical properties. Various tools have been developed to calculate the optical transmittance of multilayer thin-film structures based on the transfer-matrix method. However, the factors that affect the accuracy of these calculations have not been investigated very much. In this study, two sets of TCEs, TiO2/Au/TiO2 and TiO2/Ag/TiO2, were fabricated to study the factors that affect the accuracy of transmittance predictions. We found that the predicted transmittance can deviate significantly from measured transmittance for TCEs that have ultra-thin plasmonic metal layers. The ultrathin metal layer in the TCE is typically discontinuous. When light interacts with the metallic islands in this discontinuous layer, localized surface plasmons are generated. This causes extra light absorption, which then leads to the actual transmittance being lower than the predicted transmittance.

  6. 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. PMID:26404735

  7. Polyaniline/carbon nanofiber and organic charge transfer complex based composite electrode for electroanalytical urea detection

    NASA Astrophysics Data System (ADS)

    Das, Gautam; Yoon, Hyon Hee

    2015-06-01

    A composite electrode based on polyaniline coated modified carbon nanofiber (PANI-mCNF), tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) and urease (Ur) enzyme was evaluated as biosensor for urea detection. Homogeneous coating of PANI on the surface of mCNF was achieved by oxidative polymerization of anilium ion. Fourier transform infrared (FTIR) spectroscopy and field-emission scanning electron microscopy (FESEM) were used to analyze the structural and morphological characteristics of PANI-mCNF nanocomposite. The biosensor showed excellent electroactivity in neutral and basic medium. A linear response to urea in the concentration range of 0.5-8.4 mM with a correlation coefficient of 0.998, good sensitivity (2.84 µA cm-2 mM-1) and a fast response time (ca. 4 s) was obtained for the biosensor. The minimum detection limit was found to be 3 µM. The biosensor was stable and showed minimal loss in sensitivity, even after two months of storage. The amalgamation of the PANI and CNF synergistically enhances the performance of the biosensor for electroanalytical detection of urea.

  8. Prediction of transmittance spectra for transparent composite electrodes with ultra-thin metal layers

    SciTech Connect

    Zhao, Zhao; Alford, T. L.; Khorasani, Arash Elhami; Theodore, N. D.; Dhar, A.

    2015-11-28

    Recent interest in indium-free transparent composite-electrodes (TCEs) has motivated theoretical and experimental efforts to better understand and enhance their electrical and optical properties. Various tools have been developed to calculate the optical transmittance of multilayer thin-film structures based on the transfer-matrix method. However, the factors that affect the accuracy of these calculations have not been investigated very much. In this study, two sets of TCEs, TiO{sub 2}/Au/TiO{sub 2} and TiO{sub 2}/Ag/TiO{sub 2}, were fabricated to study the factors that affect the accuracy of transmittance predictions. We found that the predicted transmittance can deviate significantly from measured transmittance for TCEs that have ultra-thin plasmonic metal layers. The ultrathin metal layer in the TCE is typically discontinuous. When light interacts with the metallic islands in this discontinuous layer, localized surface plasmons are generated. This causes extra light absorption, which then leads to the actual transmittance being lower than the predicted transmittance.

  9. 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.

  10. Composite structural armor for combat vehicle applications

    NASA Technical Reports Server (NTRS)

    Haskell, William E., III; Alesi, A. L.; Parsons, G. R.

    1990-01-01

    Several projects that have demonstrated the advantages of using thick composite armor technology for structural applications in armored combat vehicles are discussed. The first involved composite cargo doors for the Marine Corps LVTP-7 amphibious landing vehicle. Another was a demonstration composite turret that offered a weight reduction of 15.5 percent. The advantages of this composite armor compared to metallic armors used for combat vehicle hull and turret applications are reduced weight at equal ballistic protection; reduced back armor spall; excellent corrosion resistance; reduced production costs by parts consolidation; and inherent thermal and acoustic insulative properties. Based on the encouraging results of these past programs, the Demonstration Composite Hull Program was started in September 1986. To demonstrate this composite armor technology, the Army's newest infantry fighting vehicle, the Bradley Fighting Vehicle (BFV), was selected as a model. A composite infantry fighting vehicle, designated the CIFV for this program, has been designed and fabricated and is currently undergoing a 6000 mile field endurance test. The CIFV demonstration vehicle uses the BFV engine, transmission, suspension, track and other equipment.

  11. 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

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

    PubMed

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

    2015-01-01

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

  13. Capacitive behavior of amorphous and crystalline RuO 2 composite electrode fabricated by spark plasma sintering technique

    NASA Astrophysics Data System (ADS)

    Bharali, P.; Kuratani, K.; Takeuchi, T.; Kiyobayashi, T.; Kuriyama, N.

    This study is intended to determine if the capacitive properties are improved when a specific amount of crystalline ruthenium oxide (c-RuO 2) is added to an amorphous hydrous ruthenium oxide (a-RuO 2) electrode fabricated by the spark plasma sintering technique. For at the cyclic voltammetry scan rates higher than 10 mV s -1, the capacitance of a highly pseudo-capacitive, but less electron-conductive a-RuO 2 electrode is augmented by adding 5-20 wt.% of c-RuO 2 which is less capacitive, but more electron-conductive than a-RuO 2. The capacitance fades when more than 20 wt.% of c-RuO 2 is added because the less capacitive nature of c-RuO 2 prevails. The proximate cause of this phenomenon is the electronic conductivity, σ, of the composite electrode as we observe a maximum in σ at around a 5-20 wt.% c-RuO 2 content. The fact that c-RuO 2 is composed of smaller particles than a-RuO 2 seems to be related to the maximum σ value for a certain c-RuO 2 content of the composite electrode.

  14. Stabilized composite membranes and membrane electrode assemblies for high temperature/low relative humidity polymer electrolyte fuel cell operation

    NASA Astrophysics Data System (ADS)

    Ramani, Vijay Krishna

    Polymer electrolyte membrane fuel cells (PEMFCs) have a variety of applications in the stationary power, mobile power and automotive power sectors. Existing membrane technology presently permits fuel cell operation at temperatures less than 100°C under fully saturated conditions. However, several advantages such as easier heat rejection rates and improved impurities tolerance by the anode electrocatalyst result by operating a PEMFC at elevated temperatures (above 100°C) and lower relative humidities. In an attempt to extend the operating range of the polymer electrolyte membrane, perfluorosulfonic acid (NafionRTM) based organic/inorganic (heteropolyacid) composite membranes were investigated in terms of thermal and electrochemical stability, additive stability and conductivity. Tungsten based heteropolyacids (HPAs) were found to be electrochemically stable as opposed to molybdenum based additives. The stability of the inorganic heteropolyacid additive in aqueous environments was enhanced by ion exchanging the protons of the HPAs with larger counter ions. An additional stabilization technique developed involved improving the interaction of HPA with NafionRTM by linking the particles to the sulfonic acid clusters via a sol-gel induced metal oxide linkage. The proton conductivity of the composite membranes was found to depend on the particle size of the HPA additive. A two order of magnitude change in additive particle size was attained by modification of the membrane preparation technique. This modification resulted in a nearly 50% increase in conductivity. The membranes prepared were characterized by thermal analysis, spectroscopy and microscopy. A technique was developed to incorporate existing MEA preparation and HPA stabilization techniques to the composite membranes with small HPA particles. All MEAs prepared were evaluated at high temperatures (120°C) and low relative humidities (35%) in an operating fuel cell, with membrane resistance and hence conductivity

  15. C-IOP/NiO/Ni7S6 composite with the inverse opal lattice as an electrode for supercapacitors

    NASA Astrophysics Data System (ADS)

    Sukhinina, Nadezhda S.; Masalov, Vladimir M.; Zhokhov, Andrey A.; Zverkova, Irina I.; Emelchenko, Gennadi A.

    2015-06-01

    In this work, we demonstrate the results of studies on the synthesis, the structure and properties of carbon inverted opal (C-IOP) nanostructures, the surface of which is modified by oxide and sulfide of nickel. It is shown that the modification of the matrix C-IOP by nickel compounds led to a decreasing the specific surface area more than three times and was 250 m2/g. The specific capacitance of the capacitor with the C-IOP/NiO/Ni7S6 composite as electrode has increased more than 4 times, from 130 F/g to 600 F/g, as compared with the sample C-IOP without the modification by nickel compounds. The significant contribution of the faradaic reactions in specific capacitance of the capacitor electrodes of the composites is marked.

  16. Vanadium oxide (VO) based low cost counter electrode in dye sensitized solar cell (DSSC) applications

    SciTech Connect

    Vijayakumar, P.; Pandian, Muthu Senthil; Ramasamy, P.

    2015-06-24

    Vanadium oxide nanostars were synthesized by chemical method. The prepared Vanadium oxide nanostars are introduced into dye sensitized solar cell (DSSC) as counter electrode (CE) catalyst to replace the expensive platinum (Pt). The products were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) method. The photovoltaic performance of the VO as counter electrode based DSSC was evaluated under simulated standard global AM 1.5G sunlight (100 mW/cm{sup 2}). The solar to electrical energy conversion efficiency (η) of the DSSC was found to be 0.38%.This work expands the Counter electrode catalyst, which can help to reduce the cost of DSSC and thereby encourage their fundamental research and commercial application.

  17. Facile 3D Metal Electrode Fabrication for Energy Applications via Inkjet Printing and Shape Memory Polymer

    NASA Astrophysics Data System (ADS)

    Roberts, R. C.; Wu, J.; Hau, N. Y.; Chang, Y. H.; Feng, S. P.; Li, D. C.

    2014-11-01

    This paper reports on a simple 3D metal electrode fabrication technique via inkjet printing onto a thermally contracting shape memory polymer (SMP) substrate. Inkjet printing allows for the direct patterning of structures from metal nanoparticle bearing liquid inks. After deposition, these inks require thermal curing steps to render a stable conductive film. By printing onto a SMP substrate, the metal nanoparticle ink can be cured and substrate shrunk simultaneously to create 3D metal microstructures, forming a large surface area topology well suited for energy applications. Polystyrene SMP shrinkage was characterized in a laboratory oven from 150-240°C, resulting in a size reduction of 1.97-2.58. Silver nanoparticle ink was patterned into electrodes, shrunk, and the topology characterized using scanning electron microscopy. Zinc-Silver Oxide microbatteries were fabricated to demonstrate the 3D electrodes compared to planar references. Characterization was performed using 10M potassium hydroxide electrolyte solution doped with zinc oxide (57g/L). After a 300s oxidation at 3Vdc, the 3D electrode battery demonstrated a 125% increased capacity over the reference cell. Reference cells degraded with longer oxidations, but the 3D electrodes were fully oxidized for 4 hours, and exhibited a capacity of 5.5mA-hr/cm2 with stable metal performance.

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

    PubMed

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

    2016-09-01

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

  19. 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.

  20. Perovskite electrodes and method of making the same

    SciTech Connect

    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.

  1. Flexible binder free functionalized carbon nanotube electrodes for ultracapacitor

    NASA Astrophysics Data System (ADS)

    Bhat, Badekai Ramachandra; Aravinda, L. S.; Bhat, K. Udaya

    2014-03-01

    The Flexible supercapacitor electrode material was prepared by simple spray coating technique. This will provide a greener alternative for the fabrication of binder free composite electrode for supercapacitor applications. A symmetric double layer super capacitor stack was fabricated by using flexible electrodes. The investigation of the capacitance property of the fabricated super capacitor stack was investigated using cyclic voltammetry, chronopotentiometry and electrical impedance spectroscopy studies. The flexible electrode material shows a specific capacitance of 50 Fg-1 with good cyclibility.

  2. 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.

  3. Composite Materials for Low-Temperature Applications

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Composite materials with improved thermal conductivity and good mechanical strength properties should allow for the design and construction of more thermally efficient components (such as pipes and valves) for use in fluid-processing systems. These materials should have wide application in any number of systems, including ground support equipment (GSE), lunar systems, and flight hardware that need reduced heat transfer. Researchers from the Polymer Science and Technology Laboratory and the Cryogenics Laboratory at Kennedy Space Center were able to develop a new series of composite materials that can meet NASA's needs for lightweight materials/composites for use in fluid systems and also expand the plastic-additive markets. With respect to thermal conductivity and physical properties, these materials are excellent alternatives to prior composite materials and can be used in the aerospace, automotive, military, electronics, food-packaging, and textile markets. One specific application of the polymeric composition is for use in tanks, pipes, valves, structural supports, and components for hot or cold fluid-processing systems where heat flow through materials is a problem to be avoided. These materials can also substitute for metals in cryogenic and other low-temperature applications. These organic/inorganic polymeric composite materials were invented with significant reduction in heat transfer properties. Decreases of 20 to 50 percent in thermal conductivity versus that of the unmodified polymer matrix were measured. These novel composite materials also maintain mechanical properties of the unmodified polymer matrix. These composite materials consist of an inorganic additive combined with a thermoplastic polymer material. The intrinsic, low thermal conductivity of the additive is imparted into the thermoplastic, resulting in a significant reduction in heat transfer over that of the base polymer itself, yet maintaining most of the polymer's original properties. Normal

  4. 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

  5. Fungal Exopolysaccharide: Production, Composition and Applications

    PubMed Central

    Mahapatra, Subhadip; Banerjee, Debdulal

    2013-01-01

    Fungal exopolysaccharides (EPSs) have been recognized as high value biomacromolecules for the last two decades. These products, including pullulan, scleroglucan, and botryosphaeran, have several applications in industries, pharmaceuticals, medicine, foods etc. Although fungal EPSs are highly relevant, to date information concerning fungal biosynthesis is scarce and an extensive search for new fugal species that can produce novel EPSs is still needed. In most cases, the molecular weight variations and sugar compositions of fungal EPSs are dependent to culture medium composition and different physical conditions provided during fermentation. An inclusive and illustrative review on fungal EPS is presented here. The general outline of the present work includes fungal EPS production, their compositions and applications. An emphasis is also given to listing out different fungal strains that can produce EPSs. PMID:24826070

  6. Indirect composite resin materials for posterior applications.

    PubMed

    Shellard, E; Duke, E S

    1999-12-01

    Indirect composite resin restorations were introduced a number of years ago as possible alternatives to traditional metallic or ceramic-based indirect restorations. However, the earlier formulations did not provide evidence of improvement in mechanical and physical properties over chairside-placed direct composite resin materials. Because they required more tooth structure removal than direct restorations, their use became unpopular and was abandoned by most clinicians. Over the past few years, a new class of composite resin indirect materials has surfaced in the profession. Various technologies have been suggested as reinforcement mechanisms. Fibers, matrix modifications, and an assortment of innovations have been proposed for enhancing indirect composite resin restorations. Applications are from inlay restorations all the way to multi-unit fixed prostheses. This manuscript summarizes some of the progress made in this area. When available, data is presented to provide clinicians with guidelines and indications for the use of these materials.

  7. Electrospun composite nanofibers of poly vinyl pyrrolidone and zinc oxide nanoparticles modified carbon paste electrode for electrochemical detection of curcumin.

    PubMed

    Afzali, Moslem; Mostafavi, Ali; Shamspur, Tayebeh

    2016-11-01

    A simple and novel ferrocene-nanofiber carbon paste electrode was developed to determine curcumin in a phosphate buffer solution at pH=8. ZnO nanoparticles were produced via a sonochemical process and composite nanofibers of PVP/ZnO were prepared by electrospinning. The characterization was performed by SEM, XRD and IR. The results suggest that the electrospun composite nanofibers having a large surface area promote electron transfer for the oxidation of curcumin and hence the FCNFCPE exhibits high electrocatalytic activity and performs well in regard to the oxidation of curcumin. The proposed method was successfully applied for measurement of curcumin in urine and turmeric as real samples.

  8. Dechlorination of pentachlorophenol (PCP) in aqueous solution on novel Pd-loaded electrode modified with PPy-SDBS composite film.

    PubMed

    Sun, Zhirong; Wei, Xuefeng; Zhang, Huan; Hu, Xiang

    2015-03-01

    Pentachlorophenol (PCP) is a persistent pollutant and a suspected human carcinogen. It can be found in the air, water, and soil and enters the environment through evaporation from treated wood surfaces, industrial spills, and disposal at uncontrolled hazardous waste sites. Ecotoxicity of PCP necessitates the development of rapid and reliable remediation techniques. Electrocatalytic hydrogenolysis (ECH) has been proven as a promising method for detoxification of halogenated wastes, due to its rapid reaction rate, low apparatus cost, mild reaction conditions, and absence of secondary contaminants. Challenge for the application of ECH is to prepare a Pd-coated cathode with high stability, high catalytic activity, and low Pd loading level. In this work, Pd/polypyrrole-sodium dodecyl benzene sulfonate/meshed Ti (Pd/PPy-SDBS/Ti) electrode was prepared and was characterized by cyclic voltammetry, scanning electron microscopy, X-ray diffraction, and inductively coupled plasma-atomic emission spectrometry. Electrochemically reductive dechlorination of PCP on the Pd/PPy-SDBS/Ti electrode in aqueous solution was investigated. Pd microparticles were uniformly dispersed on PPy-SDBS film which was previously electrodeposited on the meshed Ti supporting electrode. The loading of Pd on the electrode was 0.72 mg cm(-2). Electrocatalytic dechlorination of PCP was performed in a two-compartment cell separated by cation-exchange membrane. The PCP removal on the Pd/PPy-SDBS/Ti electrode could reach 100 % within 70 min with dechlorination current 3 mA when PCP initial concentration was 10 mg L(-1) and initial pH was 2.4. Conversion of PCP on the Pd/PPy-SDBS/Ti electrode followed pseudo-first-order kinetics, and the apparent activation energy was 13.0 kJ mol(-1). The removal of PCP still kept 100 % after 70 min dechlorination when the Pd/PPy-SDBS/Ti cathode was reused ten times. The electrode exhibited promising dechlorination potential with high electrocatalytic activity, good stability

  9. A novel nitrite biosensor based on conductometric electrode modified with cytochrome c nitrite reductase composite membrane.

    PubMed

    Zhang, Zhiqiang; Xia, Siqing; Leonard, Didier; Jaffrezic-Renault, Nicole; Zhang, Jiao; Bessueille, François; Goepfert, Yves; Wang, Xuejiang; Chen, Ling; Zhu, Zhiliang; Zhao, Jianfu; Almeida, M Gabriela; Silveira, Célia M

    2009-02-15

    A conductometric biosensor for nitrite detection was developed using cytochrome c nitrite reductase (ccNiR) extracted from Desulfovibrio desulfuricans ATCC 27774 cells immobilized on a planar interdigitated electrode by cross-linking with saturated glutaraldehyde (GA) vapour in the presence of bovine serum albumin, methyl viologen (MV), Nafion, and glycerol. The configuration parameters for this biosensor, including the enzyme concentration, ccNiR/BSA ratio, MV concentration, and Nafion concentration, were optimized. Various experimental parameters, such as sodium dithionite added, working buffer solution, and temperature, were investigated with regard to their effect on the conductance response of the biosensor to nitrite. Under the optimum conditions at room temperature (about 25 degrees C), the conductometric biosensor showed a fast response to nitrite (about 10s) with a linear range of 0.2-120 microM, a sensitivity of 0.194 microS/microM [NO(2)(-)], and a detection limit of 0.05 microM. The biosensor also showed satisfactory reproducibility (relative standard deviation of 6%, n=5). The apparent Michaelis-Menten constant (K(M,app)) was 338 microM. When stored in potassium phosphate buffer (100mM, pH 7.6) at 4 degrees C, the biosensor showed good stability over 1 month. No obvious interference from other ionic species familiar in natural waters was detected. The application experiments show that the biosensor is suitable for use in real water samples. PMID:18804367

  10. Effect of Solution Composition on the Energy Production by Capacitive Mixing in Membrane-Electrode Assembly

    PubMed Central

    2015-01-01

    In this work, we consider the extent to which the presence of multivalent ions in solution modifies the equilibrium and dynamics of the energy production in a capacitive cell built with ion-exchange membranes in contact with high surface area electrodes. The cell potential in open circuit (OCV) is controlled by the difference between both membrane potentials, simulated as constant volume charge regions. A theoretical model is elaborated for steady state OCV, first in the case of monovalent solutions, as a reference. This is compared to the results in multi-ionic systems, containing divalent cations in concentrations similar to those in real seawater. It is found that the OCV is reduced by about 25% (as compared to the results in pure NaCl solutions) due to the presence of the divalent ions, even in low concentrations. Interestingly, this can be related to the “uphill” transport of such ions against their concentration gradients. On the contrary, their effect on the dynamics of the cell potential is negligible in the case of highly charged membranes. The comparison between model predictions and experimental results shows a very satisfactory agreement, and gives clues for the practical application of these recently introduced energy production methods. PMID:25089164

  11. 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

  12. Monolithic multiscale bilayer inverse opal electrodes for dye-sensitized solar cell applications

    NASA Astrophysics Data System (ADS)

    Lee, Jung Woo; Moon, Jun Hyuk

    2015-03-01

    Multilayer structures in which the layers are both electrically and physically connected are critical to be used as high-performance electrodes for photovoltaic devices. We present the first multiscale bilayer inverse opal (IO) structures for application as electrodes in dye-sensitized solar cells (DSCs). A bilayer of a mesoscopic IO layer (70 nm pore diameter) and a top macroporous IO layer (215 nm and 250 nm pore diameters) was fabricated as the high-specific-area electrode and the light-harvesting enhancing layer, respectively. The mesoscopic IO layer exhibits a dye-adsorption density, which is approximately 4 times greater than that of the macroporous IO structure because of its small pore size. The macroporous IO layer exhibits a photonic bandgap reflection in the visible-light wavelength range. We incorporated the bilayer IO electrodes into DSCs and compared the effects of the pore sizes of the macroporous layers on the photocurrent densities of the DSCs. We observed that the bilayer IO electrode DSCs that contained a 250 nm IO layer exhibited photocurrent densities greater than those of 215 nm IO DSCs. This enhanced photocurrent density was achieved because the photonic bandgap (PBG) reflection wavelength matches the wavelength range in which the N719 dye has a small light-absorption coefficient. The fabrication of this structurally homogeneous IO bilayer allows a strong contact between the layers, and the resulting bilayer, therefore, exhibits a high photovoltaic performance. We believe that this bilayer structure provides an alternative approach to the development of optimized electrode structures for various devices.Multilayer structures in which the layers are both electrically and physically connected are critical to be used as high-performance electrodes for photovoltaic devices. We present the first multiscale bilayer inverse opal (IO) structures for application as electrodes in dye-sensitized solar cells (DSCs). A bilayer of a mesoscopic IO layer (70

  13. Applications for carbon fibre recovered from composites

    NASA Astrophysics Data System (ADS)

    Pickering; Liu, Z.; Turner, TA; Wong, KH

    2016-07-01

    Commercial operations to recover carbon fibre from waste composites are now developing and as more recovered fibre becomes available new applications for recovered fibre are required. Opportunities to use recovered carbon fibre as a structural reinforcement are considered involving the use of wet lay processes to produce nonwoven mats. Mats with random in-plane fibre orientation can readily be produced using existing commercial processes. However, the fibre volume fraction, and hence the mechanical properties that can be achieved, result in composites with limited mechanical properties. Fibre volume fractions of 40% can be achieved with high moulding pressures of over 100 bar, however, moulding at these pressures results in substantial fibre breakage which reduces the mean fibre length and the properties of the composite manufactured. Nonwoven mats made from aligned, short carbon fibres can achieve higher fibre volume fractions with lower fibre breakage even at high moulding pressure. A process for aligning short fibres is described and a composite of over 60% fibre volume fraction has been manufactured at a pressures up to 100 bar with low fibre breakage. Further developments of the alignment process have been undertaken and a composite of 46% fibre volume fraction has been produced moulded at a pressure of 7 bar in an autoclave, exhibiting good mechanical properties that compete with higher grade materials. This demonstrates the potential for high value applications for recovered carbon fibre by fibre alignment.

  14. Monolithic multiscale bilayer inverse opal electrodes for dye-sensitized solar cell applications.

    PubMed

    Lee, Jung Woo; Moon, Jun Hyuk

    2015-03-12

    Multilayer structures in which the layers are both electrically and physically connected are critical to be used as high-performance electrodes for photovoltaic devices. We present the first multiscale bilayer inverse opal (IO) structures for application as electrodes in dye-sensitized solar cells (DSCs). A bilayer of a mesoscopic IO layer (70 nm pore diameter) and a top macroporous IO layer (215 nm and 250 nm pore diameters) was fabricated as the high-specific-area electrode and the light-harvesting enhancing layer, respectively. The mesoscopic IO layer exhibits a dye-adsorption density, which is approximately 4 times greater than that of the macroporous IO structure because of its small pore size. The macroporous IO layer exhibits a photonic bandgap reflection in the visible-light wavelength range. We incorporated the bilayer IO electrodes into DSCs and compared the effects of the pore sizes of the macroporous layers on the photocurrent densities of the DSCs. We observed that the bilayer IO electrode DSCs that contained a 250 nm IO layer exhibited photocurrent densities greater than those of 215 nm IO DSCs. This enhanced photocurrent density was achieved because the photonic bandgap (PBG) reflection wavelength matches the wavelength range in which the N719 dye has a small light-absorption coefficient. The fabrication of this structurally homogeneous IO bilayer allows a strong contact between the layers, and the resulting bilayer, therefore, exhibits a high photovoltaic performance. We believe that this bilayer structure provides an alternative approach to the development of optimized electrode structures for various devices.

  15. Monolithic multiscale bilayer inverse opal electrodes for dye-sensitized solar cell applications.

    PubMed

    Lee, Jung Woo; Moon, Jun Hyuk

    2015-03-12

    Multilayer structures in which the layers are both electrically and physically connected are critical to be used as high-performance electrodes for photovoltaic devices. We present the first multiscale bilayer inverse opal (IO) structures for application as electrodes in dye-sensitized solar cells (DSCs). A bilayer of a mesoscopic IO layer (70 nm pore diameter) and a top macroporous IO layer (215 nm and 250 nm pore diameters) was fabricated as the high-specific-area electrode and the light-harvesting enhancing layer, respectively. The mesoscopic IO layer exhibits a dye-adsorption density, which is approximately 4 times greater than that of the macroporous IO structure because of its small pore size. The macroporous IO layer exhibits a photonic bandgap reflection in the visible-light wavelength range. We incorporated the bilayer IO electrodes into DSCs and compared the effects of the pore sizes of the macroporous layers on the photocurrent densities of the DSCs. We observed that the bilayer IO electrode DSCs that contained a 250 nm IO layer exhibited photocurrent densities greater than those of 215 nm IO DSCs. This enhanced photocurrent density was achieved because the photonic bandgap (PBG) reflection wavelength matches the wavelength range in which the N719 dye has a small light-absorption coefficient. The fabrication of this structurally homogeneous IO bilayer allows a strong contact between the layers, and the resulting bilayer, therefore, exhibits a high photovoltaic performance. We believe that this bilayer structure provides an alternative approach to the development of optimized electrode structures for various devices. PMID:25634556

  16. 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.

  17. 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

    2016-01-01

    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

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

    PubMed

    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/cm(2)), open-circuit voltage (VOC) from 0.24 to 0.55V, 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). PMID:23973582

  19. 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

  20. 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. PMID:26354251

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  2. Durability of composites in automotive structural applications

    SciTech Connect

    Corum, J.M.; Battiste, R.L.; McCoy, H.E.; Ruggles, M.B.; Simpson, W.A.; Weitsman, Y.J.

    1996-10-01

    The overall goal of the project is to develop experimentally-based, durability-driven design guidelines for automotive composite structures and to demonstrate their applicability to lightweight, manufacturable structures under representative field loading histories and environments. Key technical issues are the potentially degrading effects that (1) both cyclic and long-term sustained loadings, (2) various automotive environments, and (3) low-energy impacts can have on the dimensional stability, strength, and stiffness of automotive composite structures. The purpose of this paper is to present the findings and observations developed to date and to outline future directions.

  3. Composite Material Application to Liquid Rocket Engines

    NASA Technical Reports Server (NTRS)

    Judd, D. C.

    1982-01-01

    The substitution of reinforced plastic composite (RPC) materials for metal was studied. The major objectives were to: (1) determine the extent to which composite materials can be beneficially used in liquid rocket engines; (2) identify additional technology requirements; and (3) determine those areas which have the greatest potential for return. Weight savings, fabrication costs, performance, life, and maintainability factors were considered. Two baseline designs, representative of Earth to orbit and orbit to orbit engine systems, were selected. Weight savings are found to be possible for selected components with the substitution of materials for metal. Various technology needs are identified before RPC material can be used in rocket engine applications.

  4. Direct electrochemistry and electrocatalysis of myoglobin immobilized on Fe2O3 nanoparticle-sodium alginate-ionic liquid composite-modified electrode.

    PubMed

    Zhan, Tianrong; Xi, Mengying; Wang, Yan; Sun, Wei; Hou, Wanguo

    2010-06-01

    A biocomposite material composed of sodium alginate (SA), Fe(2)O(3) nanoparticles, and ionic liquid 1-decyl-3-methylimidazolium bromide ([DMIM]Br) was fabricated and used for the immobilization of myoglobin (Mb) on the surface of a carbon ionic liquid electrode (CILE). The CILE was fabricated by mixing graphite powder with ionic liquid N-butylpyridinium hexafluorophosphate (BPPF(6)) together. UV-Vis absorption and FTIR spectroscopic results indicated that Mb retained its native structure in the composite material. A pair of well-defined redox peaks appeared on the cyclic voltammogram in pH 7.0 phosphate buffer solution (PBS) with the formal peak potential (E(0')) at -0.256 V (versus SCE), which was the typical electrochemical behavior of Mb heme Fe(III)/Fe(II) redox couples. The Mb-modified electrode showed good electrocatalytic activity to the reduction of trichloroacetic acid (TCA) and NaNO(2) with wide linear range, good sensitivity, and reproducibility. The calibration range for TCA detection was between 0.6 and 12.0 mmol L(-1) with the linear regression equation as Iss (μA)=42.44C (mmol L(-1))+50.57 and a detection limit of 0.4 mmol L(-1) (3σ). The Mb-modified electrode also applied to NaNO(2) determination in the concentration range from 4.0 to 100.0 mmol L(-1) with a detection limit of 1.3 mmol L(-1) (3σ). So the proposed electrode has potential applications as third-generation biosensors.

  5. 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

  6. Ni-BaTiO3-Based Base-Metal Electrode (BME) Ceramic Capacitors for Space Applications

    NASA Technical Reports Server (NTRS)

    Liu, Donhang; Fetter, Lula; Meinhold, Bruce

    2015-01-01

    A multi-layer ceramic capacitor (MLCC) is a high-temperature (1350C typical) co-fired ceramic monolithic that is composed of many layers of alternately stacked oxide-based dielectric and internal metal electrodes. To make the dielectric layers insulating and the metal electrode layers conducting, only highly oxidation-resistant precious metals, such as platinum, palladium, and silver, can be used for the co-firing of insulating MLCCs in a regular air atmosphere. MLCCs made with precious metals as internal electrodes and terminations are called precious-metal electrode (PME) capacitors. Currently, all military and space-level applications only address the use of PME capacitors.

  7. Virtues of composite structures in electrode modification. Preparation and properties of poly(aniline)/nafion composite films. Technical report No. 3, September 1987-June 1988

    SciTech Connect

    Orata, D.O.; Buttry, D.A.

    1988-07-09

    Poly(aniline) (PA) is electropolymerized within thin films of precast Nafion on gold or glassy carbon electrodes. The quartz crystal microbalance (QCM) is used to aid in identification of the ionic species that undergo transport during switching of the PA between its insulating and conducting forms. The QCM frequency changes observed in solutions containing various cationic species suggest that cation transport is dominant for these composite structures. In acidic solution, a consequence of the high transport number for the proton in the composite films is shown to be an enhanced switching rate relative to the simple (non-composite) PA film. The composite PA films appear to be less resistive and therefore more electrochemically well behaved over a wider pH range than the simple PA films.

  8. Recent development of carbon electrode materials and their bioanalytical and environmental applications.

    PubMed

    Zhang, Wei; Zhu, Shuyun; Luque, Rafael; Han, Shuang; Hu, Lianzhe; Xu, Guobao

    2016-02-01

    Carbon materials have been extensively investigated due to their diversity, favorable properties, and active applications including electroanalytical chemistry. This critical review discusses new synthetic methods, novel carbon materials, new properties and electroanalytical applications of carbon materials particularly related to the preparation as well as bioanalytical and environmental applications of highly oriented pyrolytic graphite, graphene, carbon nanotubes, various carbon films (e.g. pyrolyzed carbon films, boron-doped diamond films and diamond-like carbon films) and screen printing carbon electrodes. Future perspectives in the field have also been discussed (366 references).

  9. Disposable Non-Enzymatic Glucose Sensors Using Screen-Printed Nickel/Carbon Composites on Indium Tin Oxide Electrodes.

    PubMed

    Jeon, Won-Yong; Choi, Young-Bong; Kim, Hyug-Han

    2015-01-01

    Disposable screen-printed nickel/carbon composites on indium tin oxide (ITO) electrodes (DSPNCE) were developed for the detection of glucose without enzymes. The DSPNCE were prepared by screen-printing the ITO substrate with a 50 wt% nickel/carbon composite, followed by curing at 400 °C for 30 min. The redox couple of Ni(OH)₂/NiOOH was deposited on the surface of the electrodes via cyclic voltammetry (CV), scanning from 0-1.5 V for 30 cycles in 0.1 M NaOH solution. The DSPNCE were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. The resulting electrical currents, measured by CV and chronoamperometry at 0.65 V vs. Ag/AgCl, showed a good linear response with glucose concentrations from 1.0-10 mM. Also, the prepared electrodes showed no interference from common physiologic interferents such as uric acid (UA) or ascorbic acid (AA). Therefore, this approach allowed the development of a simple, disposable glucose biosensor. PMID:26690438

  10. A Graphene Composite Material with Single Cobalt Active Sites: A Highly Efficient Counter Electrode for Dye-Sensitized Solar Cells.

    PubMed

    Cui, Xiaoju; Xiao, Jianping; Wu, Yihui; Du, Peipei; Si, Rui; Yang, Huaixin; Tian, Huanfang; Li, Jianqi; Zhang, Wen-Hua; Deng, Dehui; Bao, Xinhe

    2016-06-01

    The design of catalysts that are both highly active and stable is always challenging. Herein, we report that the incorporation of single metal active sites attached to the nitrogen atoms in the basal plane of graphene leads to composite materials with superior activity and stability when used as counter electrodes in dye-sensitized solar cells (DSSCs). A series of composite materials based on different metals (Mn, Fe, Co, Ni, and Cu) were synthesized and characterized. Electrochemical measurements revealed that CoN4 /GN is a highly active and stable counter electrode for the interconversion of the redox couple I(-) /I3 (-) . DFT calculations revealed that the superior properties of CoN4 /GN are due to the appropriate adsorption energy of iodine on the confined Co sites, leading to a good balance between adsorption and desorption processes. Its superior electrochemical performance was further confirmed by fabricating DSSCs with CoN4  /GN electrodes, which displayed a better power conversion efficiency than the Pt counterpart. PMID:27089044

  11. A Graphene Composite Material with Single Cobalt Active Sites: A Highly Efficient Counter Electrode for Dye-Sensitized Solar Cells.

    PubMed

    Cui, Xiaoju; Xiao, Jianping; Wu, Yihui; Du, Peipei; Si, Rui; Yang, Huaixin; Tian, Huanfang; Li, Jianqi; Zhang, Wen-Hua; Deng, Dehui; Bao, Xinhe

    2016-06-01

    The design of catalysts that are both highly active and stable is always challenging. Herein, we report that the incorporation of single metal active sites attached to the nitrogen atoms in the basal plane of graphene leads to composite materials with superior activity and stability when used as counter electrodes in dye-sensitized solar cells (DSSCs). A series of composite materials based on different metals (Mn, Fe, Co, Ni, and Cu) were synthesized and characterized. Electrochemical measurements revealed that CoN4 /GN is a highly active and stable counter electrode for the interconversion of the redox couple I(-) /I3 (-) . DFT calculations revealed that the superior properties of CoN4 /GN are due to the appropriate adsorption energy of iodine on the confined Co sites, leading to a good balance between adsorption and desorption processes. Its superior electrochemical performance was further confirmed by fabricating DSSCs with CoN4  /GN electrodes, which displayed a better power conversion efficiency than the Pt counterpart.

  12. Disposable Non-Enzymatic Glucose Sensors Using Screen-Printed Nickel/Carbon Composites on Indium Tin Oxide Electrodes

    PubMed Central

    Jeon, Won-Yong; Choi, Young-Bong; Kim, Hyug-Han

    2015-01-01

    Disposable screen-printed nickel/carbon composites on indium tin oxide (ITO) electrodes (DSPNCE) were developed for the detection of glucose without enzymes. The DSPNCE were prepared by screen-printing the ITO substrate with a 50 wt% nickel/carbon composite, followed by curing at 400 °C for 30 min. The redox couple of Ni(OH)2/NiOOH was deposited on the surface of the electrodes via cyclic voltammetry (CV), scanning from 0–1.5 V for 30 cycles in 0.1 M NaOH solution. The DSPNCE were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. The resulting electrical currents, measured by CV and chronoamperometry at 0.65 V vs. Ag/AgCl, showed a good linear response with glucose concentrations from 1.0–10 mM. Also, the prepared electrodes showed no interference from common physiologic interferents such as uric acid (UA) or ascorbic acid (AA). Therefore, this approach allowed the development of a simple, disposable glucose biosensor. PMID:26690438

  13. Continuous Preparation of Copper/Carbon Nanotube Composite Films and Application in Solar Cells.

    PubMed

    Luo, Xiao Gang; Le Wu, Min; Wang, Xiao Xia; Zhong, Xin Hua; Zhao, Ke; Wang, Jian Nong

    2016-02-01

    Realizing the continuous and large scale preparation of particle/carbon nanotube (CNT) composites with enhanced functionalities, and broad applications in energy conversion, harvesting, and storage systems, remains as a big challenge. Here, we report a scalable strategy to continuously prepare particle/CNT composite films in which particles are confined by CNT films. This is achieved by the continuous condensation and deposition of a cylindrical assembly of CNTs on a paper strip and the in situ incorporation of particles during the layer-by-layer deposition process. A Cu/CNT composite film is prepared as an example; such a film exhibits very high power conversion efficiency when it is used as a counter electrode in a solar cell, compared with previous materials under otherwise identical conditions. The proposed method can be extended to other CNT-based composite films with excellent functionalities for wide applications. PMID:26784865

  14. Nanoscale electrode arrays produced with microscale lithographic techniques for use in biomedical sensing applications.

    PubMed

    Terry, Jonathan G; Schmüser, Ilka; Underwood, Ian; Corrigan, Damion K; Freeman, Neville J; Bunting, Andrew S; Mount, Andrew R; Walton, Anthony J

    2013-12-01

    A novel technique for the production of nanoscale electrode arrays that uses standard microfabrication processes and micron-scale photolithography is reported here in detail. These microsquare nanoband edge electrode (MNEE) arrays have been fabricated with highly reproducible control of the key array dimensions, including the size and pitch of the individual elements and, most importantly, the width of the nanoband electrodes. The definition of lateral features to nanoscale dimensions typically requires expensive patterning techniques that are complex and low-throughput. However, the fabrication methodology used here relies on the fact that vertical dimensions (i.e. layer thicknesses) have long been manufacturable at the nanoscale using thin film deposition techniques that are well established in mainstream microelectronics. The authors report for the first time two aspects that highlight the particular suitability of these MNEE array systems for probe monolayer biosensing. The first is simulation, which shows the enhanced sensitivity to the redox reaction of the solution redox couple. The second is the enhancement of probe film functionalisation observed for the probe film model molecule, 6-mercapto-1-hexanol compared with microsquare electrodes. Such surface modification for specific probe layer biosensing and detection is of significance for a wide range of biomedical and other sensing and analytical applications. PMID:24206769

  15. Application of graphene oxide/lanthanum-modified carbon paste electrode for the selective determination of dopamine

    NASA Astrophysics Data System (ADS)

    Ye, Fengying; Feng, Chenqi; Fu, Ning; Wu, Huihui; Jiang, Jibo; Han, Sheng

    2015-12-01

    A home-made carbon paste electrode (CPE) was reformed by graphene oxide (GO)/lanthanum (La) complexes, and a modified electrode, called GO-La/CPE, was fabricated for the selective determination of dopamine (DA) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Several factors affecting the electrocatalytic performance of the modified sensor were investigated. Owning to the combination of GO and La ions, the GO-La/CPE sensor exhibited large surface area, well selectivity, good repeatability and stability in the oxidation reaction of DA. At optimal conditions, the response of the GO-La/CPE electrode for determining DA was linear in the region of 0.01-0.1 μM and 0.1-400.0 μM. The limit of detection was down to 0.32 nM (S/N = 3). In addition, this modified electrode was successfully applied to the detection of DA in real urine and serum samples by using standard adding method, showing its promising application in the electroanalysis of real samples.

  16. Application of BDD thin film electrode for electrochemical decomposition of heterogeneous aromatic compounds

    NASA Astrophysics Data System (ADS)

    Czupryniak, Justyna; Fabiańska, Aleksandra; Stepnowski, Piotr; Ossowski, Tadeusz; Bogdanowicz, Robert; Gnyba, Marcin; Siedlecka, Ewa

    2012-10-01

    The aim of the presented study is to investigate the applicability of electrochemical oxidation of aromatic compounds containing heteroatoms, e.g. waste from production of pesticides or pharmaceutics, at a borondoped diamond (BDD) electrode. The BDD electrodes were synthesized by microwave plasma enhanced chemical vapour deposition (MW PE CVD). Investigation of the electrode surface by optical microscopy and scanning electron microscopy (SEM) confirmed that the synthesized layer was continuous and formed a densely packed grain structure with an average roughness of less than 0:5 μm. The influence of important electrochemical parameters: current density, kind of reactor, pH or mixing operation, on the efficiency of the oxidation was investigated. The fouling of electrode's surface caused by the deposition of organic material was observed during CV and galvanostatic experiments. At low current density the oxidation rate constant k was low, but the current efficiency was relatively high. The BDD can be used successfully to remove heterogeneous aromatic compounds existing either as molecules or cations. During 4 h of electrolysis 95% of aromatic compounds were electrochemically decomposed to mineral forms. It was observed that the influence of the initial pH on mineralization was marginal.

  17. Application of BDD thin film electrode for electrochemical decomposition of heterogeneous aromatic compounds

    NASA Astrophysics Data System (ADS)

    Czupryniak, Justyna; Fabiańska, Aleksandra; Stepnowski, Piotr; Ossowski, Tadeusz; Bogdanowicz, Robert; Gnyba, Marcin; Siedlecka, Ewa M.

    2012-10-01

    The aim of the presented study is to investigate the applicability of electrochemical oxidation of aromatic compounds containing heteroatoms, e.g. waste from production of pesticides or pharmaceutics, at a borondoped diamond (BDD) electrode. The BDD electrodes were synthesized by microwave plasma enhanced chemical vapour deposition (MW PE CVD). Investigation of the electrode surface by optical microscopy and scanning electron microscopy (SEM) confirmed that the synthesized layer was continuous and formed a densely packed grain structure with an average roughness of less than 0 :5 μm. The influence of important electrochemical parameters: current density, kind of reactor, pH or mixing operation, on the efficiency of the oxidation was investigated. The fouling of electrode's surface caused by the deposition of organic material was observed during CV and galvanostatic experiments. At low current density the oxidation rate constant k was low, but the current efficiency was relatively high. The BDD can be used successfully to remove heterogeneous aromatic compounds existing either as molecules or cations. During 4 h of electrolysis 95% of aromatic compounds were electrochemically decomposed to mineral forms. It was observed that the influence of the initial pH on mineralization was marginal.

  18. Nanoscale electrode arrays produced with microscale lithographic techniques for use in biomedical sensing applications.

    PubMed

    Terry, Jonathan G; Schmüser, Ilka; Underwood, Ian; Corrigan, Damion K; Freeman, Neville J; Bunting, Andrew S; Mount, Andrew R; Walton, Anthony J

    2013-12-01

    A novel technique for the production of nanoscale electrode arrays that uses standard microfabrication processes and micron-scale photolithography is reported here in detail. These microsquare nanoband edge electrode (MNEE) arrays have been fabricated with highly reproducible control of the key array dimensions, including the size and pitch of the individual elements and, most importantly, the width of the nanoband electrodes. The definition of lateral features to nanoscale dimensions typically requires expensive patterning techniques that are complex and low-throughput. However, the fabrication methodology used here relies on the fact that vertical dimensions (i.e. layer thicknesses) have long been manufacturable at the nanoscale using thin film deposition techniques that are well established in mainstream microelectronics. The authors report for the first time two aspects that highlight the particular suitability of these MNEE array systems for probe monolayer biosensing. The first is simulation, which shows the enhanced sensitivity to the redox reaction of the solution redox couple. The second is the enhancement of probe film functionalisation observed for the probe film model molecule, 6-mercapto-1-hexanol compared with microsquare electrodes. Such surface modification for specific probe layer biosensing and detection is of significance for a wide range of biomedical and other sensing and analytical applications.

  19. Enzymatic deposition of Au nanoparticles on the designed electrode surface and its application in glucose detection.

    PubMed

    Zhang, Hongfang; Liu, Ruixiao; Sheng, Qinglin; Zheng, Jianbin

    2011-02-01

    This paper reported the enzymatic deposition of Au nanoparticles (AuNPs) on the designed 3-mercapto-propionic acid/glucose oxidase/chitosan (MPA/GOD/Chit) modified glassy carbon electrode and its application in glucose detection. Chit served as GOD immobilization matrix and interacted with MPA through electrostatic attraction. AuNPs, without nano-seeds presented on the electrode surface, was produced through the glucose oxidase catalyzed oxidation of glucose. The mechanism of production of AuNPs was confirmed to be that enzymatic reaction products H(2)O(2) in the solution reduce gold complex to AuNPs. The characterizations of the electrode modified after each assembly step was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy showed the average particle size of the AuNPs is 40nm with a narrow particle size distribution. The content of AuNPs on the electrode surfaces was measured by differential pulse stripping voltammetry. The electrochemical signals on voltammogram showed a linear increase with the glucose concentration in the range of 0.010-0.12mM with a detection limit of 4μM. This provided a method to the determination of glucose. PMID:21115279

  20. Microbubble Compositions, Properties and Biomedical Applications

    PubMed Central

    Sirsi, Shashank

    2010-01-01

    Over the last decade, there has been significant progress towards the development of microbubbles as theranostics for a wide variety of biomedical applications. The unique ability of microbubbles to respond to ultrasound makes them useful agents for contrast ultrasound imaging, molecular imaging, and targeted drug and gene delivery. The general composition of a microbubble is a gas core stabilized by a shell comprised of proteins, lipids or polymers. Each type of microbubble has its own unique advantages and can be tailored for specialized functions. In this review, different microbubbles compositions and physiochemical properties are discussed in the context of current progress towards developing novel constructs for biomedical applications, with specific emphasis on molecular imaging and targeted drug/gene delivery. PMID:20574549

  1. 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.

  2. Electrochemical determination of Sudan I in food products using a carbon nanotube-ionic liquid composite modified electrode.

    PubMed

    Liu, Benzhi; Yin, Chuntao; Wang, Min

    2014-01-01

    A sensitive and convenient electrochemical method was developed for the determination of Sudan I using a carbon nanotube-ionic liquid composite modified electrode with the enhancement effect of cetyltrimethyl ammonium bromide (CTAB). The modified electrode exhibited an obvious electrocatalytic activity towards the oxidation of Sudan I, and the oxidation peak current significantly increased in the presence of CTAB. The experimental parameters, such as solution pH, concentration of CTAB and accumulation time, were optimised for Sudan I determination. The oxidation peak current showed a linear relationship with the concentration of Sudan I in the range of 3.0 × 10(-8) to 3.1 × 10(-6) mol l(-1), with a detection limit of 8.0 × 10(-9) mol l(-1). The proposed method was successfully applied for the determination of Sudan I in food products of ketchup and chilli sauce. PMID:25254422

  3. Structural Ceramic Composites for Nuclear Applications

    SciTech Connect

    William Windes; P.A. Lessing; Y. Katoh; L. L. Snead; E. Lara-Curzio; J. Klett; C. Henager, Jr.; R. J. Shinavski

    2005-08-01

    A research program has been established to investigate fiber reinforced ceramic composites to be used as control rod components within a Very High Temperature Reactor. Two candidate systems have been identified, carbon fiber reinforced carbon (Cf/C) and silicon carbide fiber reinforced silicon carbide (SiCf/SiC) composites. Initial irradiation stability studies to determine the maximum dose for each composite type have been initiated within the High Flux Isotope Reactor at Oak Ridge National Laboratory. Test samples exposed to 10 dpa irradiation dose have been completed with future samples to dose levels of 20 and 30 dpa scheduled for completion in following years. Mechanical and environmental testing is being conducted concurrently at the Idaho National Laboratory and at Pacific Northwest National Laboratory. High temperature test equipment, testing methodologies, and test samples for high temperature (up to 1600º C) tensile strength and long duration creep studies have been established. Specific attention was paid to the architectural fiber preform design as well as the materials used in construction of the composites. Actual testing of both tubular and flat, "dog-bone" shaped tensile composite specimens will begin next year. Since there is no precedence for using ceramic composites within a nuclear reactor, ASTM standard test procedures will be established from these mechanical and environmental tests. Close collaborations between the U.S. national laboratories and international collaborators (i.e. France and Japan) are being forged to establish both national and international test standards to be used to qualify ceramic composites for nuclear reactor applications.

  4. Flexible transparent conducting composite films using a monolithically embedded AgNW electrode with robust performance stability

    NASA Astrophysics Data System (ADS)

    Im, Hyeon-Gyun; Jin, Jungho; Ko, Ji-Hoon; Lee, Jaemin; Lee, Jung-Yong; Bae, Byeong-Soo

    2013-12-01

    We report on the performance of an all-in-one flexible hybrid conducting film employing a monolithically embedded AgNW transparent electrode and a high-performance glass-fabric reinforced composite substrate (AgNW-GFRHybrimer film). Specifically, we perform in-depth investigations on the stability of the AgNW-GFRHybrimer film against heat, thermal oxidation, and wet chemicals to demonstrate the potential of the hybrid conducting film as a robust electrode platform for thin-film optoelectronic devices. With the ease of large-area processability, smooth surface topography, and robust performance stability, the AgNW-GFRHybrimer film can be a promising platform for high-performance optoelectronic devices.We report on the performance of an all-in-one flexible hybrid conducting film employing a monolithically embedded AgNW transparent electrode and a high-performance glass-fabric reinforced composite substrate (AgNW-GFRHybrimer film). Specifically, we perform in-depth investigations on the stability of the AgNW-GFRHybrimer film against heat, thermal oxidation, and wet chemicals to demonstrate the potential of the hybrid conducting film as a robust electrode platform for thin-film optoelectronic devices. With the ease of large-area processability, smooth surface topography, and robust performance stability, the AgNW-GFRHybrimer film can be a promising platform for high-performance optoelectronic devices. Electronic supplementary information (ESI) available: Further characteristics of AgNW-GFRHybrimer films and thermal oxidation of AgNW on glass. See DOI: 10.1039/c3nr05348b

  5. Enhanced performance of TiO2 nanoparticle and aerogel composite electrode for dye sensitized solar cell.

    PubMed

    Kim, Chang-Yeoul; Park, Yu-Sik; Hwang, Hae-Jin

    2012-04-01

    To evaluate the effects of specific surface area to the photocurrent conversion efficiency of dye-sensitized solar cell (DSC), we adopted TiO2 aerogel (TA)/nanoparticle (TP) composite as a photoelectrode. We prepared three types of photoelectrodes, TPs, TAs, and TATPs (1:1 TAs and TPs composite photoelectrode). The performance of TATP composite electrode was compared with that of TP and TAs. TATPs showed the improved cell efficiency, more than 0.5%, compared with a reference TPs below 15 micrometer thickness. Although the introduction of TAs increases the specific surface area for the dye adsorption, DSC composed of only TAs does not show the best efficiency result due to the crack generation. In conclusion, to produce the best photocurrent conversion efficiency, the high specific surface area of TiO2 photoelectrode for high dye adsorption should be balanced with proper control of the good electron transfer path. PMID:22849065

  6. 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

    2013-10-01

    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.

  7. Development of molecular precursors for deposition of indium sulphide thin film electrodes for photoelectrochemical applications.

    PubMed

    Ehsan, Muhammad Ali; Peiris, T A Nirmal; Wijayantha, K G Upul; Olmstead, Marilyn M; Arifin, Zainudin; Mazhar, Muhammad; Lo, K M; McKee, Vickie

    2013-08-14

    Symmetrical and unsymmetrical dithiocarbamato pyridine solvated and non-solvated complexes of indium(III) with the general formula [In(S2CNRR')3]·n(py) [where py = pyridine; R,R' = Cy, n = 2 (1); R,R' = (i)Pr, n = 1.5 (2); NRR' = Pip, n = 0.5 (3) and R = Bz, R' = Me, n = 0 (4)] have been synthesized. The compositions, structures and properties of these complexes have been studied by means of microanalysis, IR and (1)H-NMR spectroscopy, X-ray single crystal and thermogravimetric (TG/DTG) analyses. The applicability of these complexes as single source precursors (SSPs) for the deposition of β-In2S3 thin films on fluorine-doped SnO2 (FTO) coated conducting glass substrates by aerosol-assisted chemical vapour deposition (AACVD) at temperatures of 300, 350 and 400 °C is studied. All films have been characterized by powder X-ray diffraction (PXRD) and energy dispersive X-ray analysis (EDX) for the detection of phase and stoichiometry of the deposit. Scanning electron microscopy (SEM) studies reveal that precursors (1)-(4), irrespective of different metal ligand design, generate comparable morphologies of β-In2S3 thin films at different temperatures. Direct band gap energies of 2.2 eV have been estimated from the UV-vis spectroscopy for the β-In2S3 films fabricated from precursors (1) and (4). The photoelectrochemical (PEC) properties of β-In2S3 were confirmed by recording the current-voltage plots under light and dark conditions. The plots showed anodic photocurrent densities of 1.25 and 0.65 mA cm(-2) at 0.23 V vs. Ag/AgCl for the β-In2S3 films made at 400 and 350 °C from the precursors (1) and (4), respectively. The photoelectrochemical performance indicates that the newly synthesised precursors are highly useful in fabricating β-In2S3 electrodes for solar energy harvesting and optoelectronic application. PMID:23787951

  8. Electrodeposited polypyrrole/carbon nanotubes composite films electrodes for neural interfaces.

    PubMed

    Lu, Yi; Li, Tao; Zhao, Xueqing; Li, Mei; Cao, Yuliang; Yang, Hanxi; Duan, Yanwen Y

    2010-07-01

    The search for new electrode materials including new electrode modification methods is crucial for improving long-term performance of neuroprosthetic devices. In this study, an investigation of electrochemically co-deposited polypyrrole/single-walled carbon nanotube (PPy/SWCNT) films for improving the electrode-neural interface was reported. The PPy/SWCNT microelectrodes exhibited a particularly high safe charge injection (Q(inj)) limit of approximately 7.5 mC/cm(2) and low electrode impedance at 1 kHz, as well as good stability. Cell attachment and neurite outgrowth of rat pheochromocytoma (PC12) cells on the PPy/SWCNT deposited substrates were clearly observed by Calcein-AM staining and scanning electron microscope (SEM) analysis. Furthermore, tissue response was studied by a 6-week implantation in the cortex of rats. A significantly lower (p<0.05) glial fibrillary acidic protein (GFAP) and higher (p<0.05) neuronal nuclei (NeuN) immunostaining were found on comparison of the test group (n=11) with the control group (n=8), in the zone within the distance of 100 microm to the implant interface. All of these characteristics are desirable for chronically implantable neural probes with high density microelectrodes. Importantly, this technique can easily incorporate other modification methods to build a more advanced electrode-neural interface.

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

    PubMed

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

    2015-07-22

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

  10. Laser-based surface preparation of composite laminates leads to improved electrodes for electrical measurements

    NASA Astrophysics Data System (ADS)

    Almuhammadi, Khaled; Selvakumaran, Lakshmi; Alfano, Marco; Yang, Yang; Bera, Tushar Kanti; Lubineau, Gilles

    2015-12-01

    Electrical impedance tomography (EIT) is a low-cost, fast and effective structural health monitoring technique that can be used on carbon fiber reinforced polymers (CFRP). Electrodes are a key component of any EIT system and as such they should feature low resistivity as well as high robustness and reproducibility. Surface preparation is required prior to bonding of electrodes. Currently this task is mostly carried out by traditional sanding. However this is a time consuming procedure which can also induce damage to surface fibers and lead to spurious electrode properties. Here we propose an alternative processing technique based on the use of pulsed laser irradiation. The processing parameters that result in selective removal of the electrically insulating resin with minimum surface fiber damage are identified. A quantitative analysis of the electrical contact resistance is presented and the results are compared with those obtained using sanding.

  11. 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.

  12. Facile Preparation and Lithium Storage Properties of TiO2 @Graphene Composite Electrodes with Low Carbon Content.

    PubMed

    Guo, Sheng-Qi; Zhen, Meng-Meng; Liu, Lu; Yuan, Zhi-Hao

    2016-08-16

    Over the past decade, TiO2 /graphene composites as electrodes for lithium ion batteries have attracted a great deal of attention for reasons of safety and environmental friendliness. However, most of the TiO2 /graphene electrodes have large graphene content (9-40 %), which is bound to increase the cost of the battery. Logically, reducing the amount of graphene is a necessary part to achieve a green battery. The synthesis of TiO2 nanosheets under solvothermal conditions without additives is now demonstrated. Through mechanical mixing TiO2 nanosheets with different amount of reduced graphene (rGO), a series of TiO2 @graphene composites was prepared with low graphene content (rGO content 1, 2, 3, and 5 wt %). When these composites were evaluated as anodes for lithium ion batteries, it was found that TiO2 +3 wt % rGO manifested excellent cycling stability and a high specific capacity (243.7 mAh g(-1) at 1 C; 1 C=167.5 mA g(-1) ), and demonstrated superior high-rate discharge/charge capability at 20 C. PMID:27339820

  13. Non-invasive method for selection of electrodes and stimulus parameters for FES applications with intrafascicular arrays

    NASA Astrophysics Data System (ADS)

    Dowden, B. R.; Frankel, M. A.; Normann, R. A.; Clark, G. A.

    2012-02-01

    High-channel-count intrafascicular electrode arrays provide comprehensive and selective access to the peripheral nervous system. One practical difficulty in using several electrode arrays to evoke coordinated movements in paralyzed limbs is the identification of the appropriate stimulation channels and stimulus parameters to evoke desired movements. Here we present the use of a six degree-of-freedom load cell placed under the foot of a feline to characterize the muscle activation produced by three 100-electrode Utah Slanted Electrode Arrays (USEAs) implanted into the femoral nerves, sciatic nerves, and muscular branches of the sciatic nerves of three cats. Intramuscular stimulation was used to identify the endpoint force directions produced by 15 muscles of the hind limb, and these directions were used to classify the forces produced by each intrafascicular USEA electrode as flexion or extension. For 451 USEA electrodes, stimulus intensities for threshold and saturation muscle forces were identified, and the 3D direction and linearity of the force recruitment curves were determined. Further, motor unit excitation independence for 198 electrode pairs was measured using the refractory technique. This study demonstrates the utility of 3D endpoint force monitoring as a simple and non-invasive metric for characterizing the muscle-activation properties of hundreds of implanted peripheral nerve electrodes, allowing for electrode and parameter selection for neuroprosthetic applications.

  14. Application of atmospheric pressure plasma in polymer and composite adhesion

    NASA Astrophysics Data System (ADS)

    Yu, Hang

    An atmospheric pressure helium and oxygen plasma was used to investigate surface activation and bonding in polymer composites. This device was operated by passing 1.0-3.0 vol% of oxygen in helium through a pair of parallel plate metal electrodes powered by 13.56 or 27.12 MHz radio frequency power. The gases were partially ionized between the capacitors where plasma was generated. The reactive species in the plasma were carried downstream by the gas flow to treat the substrate surface. The temperature of the plasm gas reaching the surface of the substrate did not exceed 150 °C, which makes it suitable for polymer processing. The reactive species in the plasma downstream includes ~ 1016-1017 cm-3 atomic oxygen, ~ 1015 cm-3 ozone molecule, and ~ 10 16 cm-3 metastable oxygen molecule (O2 1Deltag). The substrates were treated at 2-5 mm distance from the exit of the plasma. Surface properties of the substrates were characterized using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). Subsequently, the plasma treated samples were bonded adhesively or fabricated into composites. The increase in mechanical strength was correlated to changes in the material composition and structure after plasma treatment. The work presented hereafter establishes atmospheric pressure plasma as an effective method to activate and to clean the surfaces of polymers and composites for bonding. This application can be further expanded to the activation of carbon fibers for better fiber-resin interactions during the fabrication of composites. Treating electronic grade FR-4 and polyimide with the He/O2 plasma for a few seconds changed the substrate surface from hydrophobic to hydrophilic, which allowed complete wetting of the surface by epoxy in underfill applications. Characterization of the surface by X-ray photoelectron spectroscopy shows formation of oxygenated functional groups, including hydroxyl, carbonyl, and

  15. Effect Of Dynamic Characteristics of Power Supplies on Aerosol Composition While Welding With Coated Electrodes

    NASA Astrophysics Data System (ADS)

    Il'yaschenko, D. P.; Chinakhov, D. A.; Sadikov, I. D.

    2016-08-01

    In the context of a significant increase in production output and use of welding technologies in the manufacturing of engineering products the problem of hygienic characteristics of working conditions in arc fusion welding is becoming increasingly important. The work represents how the dynamic characteristics of a power supply affect the transfer of alloying elements from a coated electrode into a base metal, a slag phase and a solid component of welding fumes. Short-circuit current limiting in inverters reduces overheating of electrode metal drops by 15%; welding fumes quantitative component - to 38%; manganese - to 30%; thermal radiation intensity - by 37%.

  16. 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.

  17. Development, characterization and applications of electrodes modified with conductive polymers, ionic liquids and proteins

    NASA Astrophysics Data System (ADS)

    Tang, Yijun

    My research involves both fundamental studies and applications of the electrodes whose surfaces are chemically modified. Conductive polymers are one of the major materials that are used to modify electrode surfaces. The thorough understanding of the behavior of conductive polymers in ionic liquids is interesting and important as the ionic liquids are becoming promising solvents. With poly(vinyl ferrocene) as the model conductive polymer, electrochemical studies were performed in various ionic liquid electrolytes. A theoretical square model and dynamic equilibrium were proposed to describe the interaction between conductive polymers and ionic liquids when the electrons transferred between the electrode and electrolyte. These findings were applied to enable and accelerate the structure relaxation of conductive polymers so that the conductive polymers were capable of delivering peptides efficiently. Incorporation of metallic nanoparticles to the conductive polymer matrix entitled new properties to the conductive polymer, increasing conductivity and providing catalytic abilities. This modification on electrode surface might bring potential uses in gas sensing, energy storage, energy conversion, etc. Conductive polymer coated electrodes produced unique double layer in ionic liquids and a fundamental study of quantum charging help to understand the double layer properties. I also studied the application of surface modified electrodes in chemo- and biosensing. A nonregeneration protocol was created to save the cost and the time in analyzing interfacial binding activities and to prevent the potential of deterioration caused to biological ligands by the conventional regeneration. In the study of carbohydrate/protein interactions, a "click" chemical reaction was first used in constructing a carbohydrate-based biosensor, which was capable of detecting and analyzing proteins specifically and accurately. In another biosensor design, the hydrogen bonding between the template and

  18. Application of geoelectric methods using buried electrodes in exploration and mining

    SciTech Connect

    Draskovits, P.; Simon, A. )

    1992-07-01

    In this paper various geoelectric methods which have been developed and applied in the last 10-20 years in ELGI are discussed. These methods which use buried electrodes are: hole-to-surface gradient mapping to detect bauxite deposits in sinkholes below a resistive screening layer; in-mine gradient profiling to map the basement topography below galleries; and the hole-to-surface version of geoelectric layer tracing to find outcrops of mineralized zones penetrated by drillings. Data processing procedures have been developed on the basis of common concepts and hypotheses to link theoretical models with geological structures. The objects investigated are determined as the difference between the theoretical models and geological structures. Examples illustrate the solution of the above-mentioned geological problems by the practical application of adequate geoelectric methods using buried electrodes.

  19. 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.

  20. (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.

  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. Electrospun composite nanofibers of poly vinyl pyrrolidone and zinc oxide nanoparticles modified carbon paste electrode for electrochemical detection of curcumin.

    PubMed

    Afzali, Moslem; Mostafavi, Ali; Shamspur, Tayebeh

    2016-11-01

    A simple and novel ferrocene-nanofiber carbon paste electrode was developed to determine curcumin in a phosphate buffer solution at pH=8. ZnO nanoparticles were produced via a sonochemical process and composite nanofibers of PVP/ZnO were prepared by electrospinning. The characterization was performed by SEM, XRD and IR. The results suggest that the electrospun composite nanofibers having a large surface area promote electron transfer for the oxidation of curcumin and hence the FCNFCPE exhibits high electrocatalytic activity and performs well in regard to the oxidation of curcumin. The proposed method was successfully applied for measurement of curcumin in urine and turmeric as real samples. PMID:27524081

  3. Electrodes for high-definition transcutaneous DC stimulation for applications in drug delivery and electrotherapy, including tDCS.

    PubMed

    Minhas, Preet; Bansal, Varun; Patel, Jinal; Ho, Johnson S; Diaz, Julian; Datta, Abhishek; Bikson, Marom

    2010-07-15

    Transcutaneous electrical stimulation is applied in a range of biomedical applications including transcranial direct current stimulation (tDCS). tDCS is a non-invasive procedure where a weak direct current (<2 mA) is applied across the scalp to modulate brain function. High-definition tDCS (HD-tDCS) is a technique used to increase the spatial focality of tDCS by passing current across the scalp using <12 mm diameter electrodes. The purpose of this study was to design and optimize "high-definition" electrode-gel parameters for electrode durability, skin safety and subjective pain. Anode and cathode electrode potential, temperature, pH and subjective sensation over time were assessed during application of 2 mA direct current, for up to 22 min on agar gel or subject forearms. A selection of five types of solid-conductors (Ag pellet, Ag/AgCl pellet, rubber pellet, Ag/AgCl ring and Ag/AgCl disc) and seven conductive gels (Signa, Spectra, Tensive, Redux, BioGel, Lectron and CCNY-4) were investigated. The Ag/AgCl ring in combination with CCNY-4 gel resulted in the most favorable outcomes. Under anode stimulations, electrode potential and temperature rises were generally observed in all electrode-gel combinations except for Ag/AgCl ring and disc electrodes. pH remained constant for all solid-conductors except for both Ag and rubber pellet electrodes with Signa and CCNY-4 gels. Sensation ratings were independent of stimulation polarity. Ag/AgCl ring electrodes were found to be the most comfortable followed by Ag, rubber and Ag/AgCl pellet electrodes across all gels.

  4. Immobilization of Prussian Blue nanoparticles onto thiol SAM modified Au electrodes for electroanalytical or biosensor applications.

    PubMed

    Miao, Yuqing; Chen, Jianrong; Wu, Xiaohua; Fang, Keming; Jia, Aiping; Liu, Jiwei

    2007-08-01

    Poly(vinylpyrrolidone) (PVP)-protected Prussian Blue (PB) nanoparticles were prepared by simply mixing FeCI3 and K4Fe(CN)6 with absence or presence of HCI or/and KCI in water solution. The obtained PB nanoparticles were immobilized onto thiol self-assembled monolayer (SAM) modified Au electrodes. L-cysteine (Cys) and 1,8-octanedithiol (ODT) were compared as a bridge between the gold surface and the PB nanoparticles. The results show that PB prepared from the initial solution with KCI gives preferred electrochemical response and that Cys/Au shows improved immobilization effect of PB than ODT/Au. The obtained PB/Cys/Au electrodes exhibit electrocatalytic activity toward H2O2 reduction and DL-homocysteine (HCys) oxidation. Glucose oxidase (GOX) was immobilized onto PB modified electrode to explore the potentials for the design of oxidase-based biosensors. It is possible to anchor PB nanoparticles and develop their application on electroanalysis and biosensing.

  5. Carbon nanotube - reduced graphene oxide composites for thermal energy harvesting applications.

    PubMed

    Romano, Mark S; Li, Na; Antiohos, Dennis; Razal, Joselito M; Nattestad, Andrew; Beirne, Stephen; Fang, Shaoli; Chen, Yongsheng; Jalili, Rouhollah; Wallace, Gordon G; Baughman, Ray; Chen, Jun

    2013-12-01

    By controlling the SWNT-rGO electrode composition and thickness to attain the appropriate porosity and tortuosity, the electroactive surface area is maximized while rapid diffusion of the electrolyte through the electrode is maintained. This leads to an increase in exchange current density between the electrode and electrolyte which results in enhanced thermocell performance. PMID:24167027

  6. Preparation, characterization and application of Nano CdS doped with alum composite electrolyte

    NASA Astrophysics Data System (ADS)

    Singh, Pramod K.; Kumar, Pawan; Seth, Tanay; Rhee, Hee-Woo; Bhattacharya, B.

    2012-09-01

    A new composite electrolyte has been developed for electrochemical application and studied in details. The system contains Alum doped with nanosize cadmium sulphide (CdS) particles in the desire ratio. The structural studies were carried out by using X-ray diffraction (XRD) as well as infrared spectroscopy (IR) which affirms the composite nature of the system. The electrical properties, including ion transport studies and complex impedance spectra confirm the ionic nature of sample as well as enhancement in ionic conductivity by CdS doping. The temperature dependence measurement confirms the Arrhenius nature of sample, which is commonly observed in the ionic composite system. The dielectric constant varies with temperature, and this data is used to calculate the number of charge carrier (n/no) contributing to conductivity and fits well with emf variation. A cell was fabricated by sandwiching the composite between graphite and stainless steel electrodes, which shows an emf of 7 mV.

  7. Synthesis and application of polypyrrole/carrageenan nano-bio composite as a cathode catalyst in microbial fuel cells.

    PubMed

    Esmaeili, Chakavak; Ghasemi, Mostafa; Heng, Lee Yook; Hassan, Sedky H A; Abdi, Mahnaz M; Daud, Wan Ramli Wan; Ilbeygi, Hamid; Ismail, Ahmad Fauzi

    2014-12-19

    A novel nano-bio composite polypyrrole (PPy)/kappa-carrageenan(KC) was fabricated and characterized for application as a cathode catalyst in a microbial fuel cell (MFC). High resolution SEM and TEM verified the bud-like shape and uniform distribution of the PPy in the KC matrix. X-ray diffraction (XRD) has approved the amorphous structure of the PPy/KC as well. The PPy/KC nano-bio composites were then studied as an electrode material, due to their oxygen reduction reaction (ORR) ability as the cathode catalyst in the MFC and the results were compared with platinum (Pt) as the most common cathode catalyst. The produced power density of the PPy/KC was 72.1 mW/m(2) while it was 46.8 mW/m(2) and 28.8 mW/m(2) for KC and PPy individually. The efficiency of the PPy/KC electrode system is slightly lower than a Pt electrode (79.9 mW/m(2)) but due to the high cost of Pt electrodes, the PPy/KC electrode system has potential to be an alternative electrode system for MFCs. PMID:25263889

  8. Synthesis and application of polypyrrole/carrageenan nano-bio composite as a cathode catalyst in microbial fuel cells.

    PubMed

    Esmaeili, Chakavak; Ghasemi, Mostafa; Heng, Lee Yook; Hassan, Sedky H A; Abdi, Mahnaz M; Daud, Wan Ramli Wan; Ilbeygi, Hamid; Ismail, Ahmad Fauzi

    2014-12-19

    A novel nano-bio composite polypyrrole (PPy)/kappa-carrageenan(KC) was fabricated and characterized for application as a cathode catalyst in a microbial fuel cell (MFC). High resolution SEM and TEM verified the bud-like shape and uniform distribution of the PPy in the KC matrix. X-ray diffraction (XRD) has approved the amorphous structure of the PPy/KC as well. The PPy/KC nano-bio composites were then studied as an electrode material, due to their oxygen reduction reaction (ORR) ability as the cathode catalyst in the MFC and the results were compared with platinum (Pt) as the most common cathode catalyst. The produced power density of the PPy/KC was 72.1 mW/m(2) while it was 46.8 mW/m(2) and 28.8 mW/m(2) for KC and PPy individually. The efficiency of the PPy/KC electrode system is slightly lower than a Pt electrode (79.9 mW/m(2)) but due to the high cost of Pt electrodes, the PPy/KC electrode system has potential to be an alternative electrode system for MFCs.

  9. Composite Solid Electrolyte for Li Battery Applications

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, G.; Attia, A. I.; Halpert, G.; Peled, E.

    1993-01-01

    The electrochemical, bulk and interfacial properties of the polyethylene oxide (PEO) based composite solid electrolyte (CSE) comprising LiI, PEO, and Al2O3 have been evaluated for Li battery applications. The bulk interfacial and transport properties of the CSEs seem to strongly depend on the alumina particle size. For the CSE films with 0.05 micron alumina while the bulk conductivity is around 10(exp -4) (mho/cm) at 103 C, the Li ion transport number seems to be close to unity at the same temperature. Compared to the PEO electrolyte this polymer composite electrolyte seems to exhibit robust mechanical and interfacial properties. We have studied three different films with three different alumina sizes in the range 0.01-0.3 micron. Effects of Al2O3 particle size on the electrochemical performance of polymer composite electrolyte is discussed. With TiS2 as cathode a 10 mAh small capacity cell was charged and discharged at C/40 and C/20 rates respectively.

  10. The Application of Nafion Metal Catalyst Free Carbon Nanotube Modified Gold Electrode: Voltammetric Zinc Detection in Serum

    PubMed Central

    Yue, Wei; Bange, Adam; Riehl, Bill L.; Johnson, Jay M.; Papautsky, Ian; Heineman, William R.

    2013-01-01

    Metal catalyst free carbon nanotube (MCFCNT) whiskers were first used as an electrode modification material on a gold electrode surface for zinc voltammetric measurements. A composite film of Nafion and MCFCNT whiskers was applied to a gold electrode surface to form a mechanically stable sensor. The sensor was then used for zinc detection in both acetate buffer solution and extracted bovine serum solution. A limit of detection of 53 nM was achieved for a 120 s deposition time. The zinc in bovine serum was extracted via a double extraction procedure using dithizone in chloroform as a zinc chelating ligand. The modified electrode was found to be both reliable and sensitive for zinc measurements in both matrices. PMID:24436574

  11. 1-3 piezoelectric composites for high temperature transducer applications

    PubMed Central

    Li, Lili; Zhang, Shujun; Xu, Zhuo; Wen, Fei; Geng, Xuecang; Lee, Hyeong Jae; Shrout, Thomas R.

    2013-01-01

    High temperature Pb(Zr,Ti)O3 /epoxy 1-3 composites were fabricated using the dice and fill method. The epoxy filler was modified with glass spheres in order to improve the thermal reliability of the composites at elevated temperatures. Temperature dependent dielectric and electromechanical properties of the composites were measured after aging at 250°C with different dwelling times. Obvious cracks were observed and the electrodes were damaged in the composite with unmodified epoxy after 200 hours, leading to the failure of the composite. In contrast, composites with >12 vol% glass sphere loaded epoxies were found to exhibit minimal electrical property variation after aging for 500 hours, with dielectric permittivity, piezoelectric coefficient and electromechanical coupling being on the order of 940, 310pC/N and 57%, respectively. This is due to the improved thermal expansion behavior of the modified filler. PMID:23729863

  12. 1-3 piezoelectric composites for high temperature transducer applications.

    PubMed

    Li, Lili; Zhang, Shujun; Xu, Zhuo; Wen, Fei; Geng, Xuecang; Lee, Hyeong Jae; Shrout, Thomas R

    2013-04-24

    High temperature Pb(Zr,Ti)O3 /epoxy 1-3 composites were fabricated using the dice and fill method. The epoxy filler was modified with glass spheres in order to improve the thermal reliability of the composites at elevated temperatures. Temperature dependent dielectric and electromechanical properties of the composites were measured after aging at 250°C with different dwelling times. Obvious cracks were observed and the electrodes were damaged in the composite with unmodified epoxy after 200 hours, leading to the failure of the composite. In contrast, composites with >12 vol% glass sphere loaded epoxies were found to exhibit minimal electrical property variation after aging for 500 hours, with dielectric permittivity, piezoelectric coefficient and electromechanical coupling being on the order of 940, 310pC/N and 57%, respectively. This is due to the improved thermal expansion behavior of the modified filler.

  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. 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.

  15. 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. PMID:27490161

  16. Polymer light harvesting composites for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Sun, Sam-Shajing; Wang, Dan

    2015-09-01

    Polymer based optoelectronic composites and thin film devices exhibit great potential in space applications due to their lightweight, flexible shape, high photon absorption coefficients, and robust radiation tolerance in space environment. Polymer/dye composites appear promising for optoelectronics applications due to potential enhancements in both light harvesting and charge separation. In this study, the optoelectronic properties of a series of molecular dyes paired with a conjugated polymer Poly(3-hexylthiophene-2,5-diyl) (P3HT) were investigated. Specifically, the solution PL quenching coefficients (Ksv) of dye/polymer follows a descending order from dyes of Chloro(protoporphyrinato)iron(III) (Hemin), Protoporphyrin, to meso-Tetra(4-carboxyphenyl)porphine (TCPP). In optoelectronic devices made of the P3HT/dye/PCBM composites, the short circuit current densities Jsc as well as the overall power conversion efficiencies (PCE) also follow a descending order from Hemin, Protoporphyrin, to TCPP, despite Hemin exhibits the intermediate polymer/dye LUMO (lowest unoccupied molecular orbital) offset and lowest absorption coefficient as compared to the other two dyes, i.e., the cell optoelectronic efficiency did not follow the LUMO offsets which are the key driving forces for the photo induced charge separations. This study reveals that too large LUMO offset or electron transfer driving force may result in smaller PL quenching and optoelectronic conversion efficiency, this could be another experimental evidence for the Marcus electron transfer model, particularly for the Marcus `inverted region'. It appears an optimum electron transfer driving force or strong PL quenching appears more critical than absorption coefficient for optoelectronic conversion devices.

  17. Nanostructured metal-polyaniline composites and applications thereof

    DOEpatents

    Wang, Hsing-Lin; Li, Wenguang; Bailey, James A.; Gao, Yuan

    2012-10-02

    Metal-polyaniline (PANI) composites are provided together with a process of preparing such composites by an electrodeless process. The metal of the composite can have nanoscale structural features and the composites can be used in applications such as catalysis for hydrogenation reactions and for analytical detection methods employing SERS.

  18. Microstructures and Dielectric Characteristics of Ultrafine-Grained Barium Titanate-Based Ceramics for Base-Metal-Electrode Multilayer Ceramic Capacitors Applications

    NASA Astrophysics Data System (ADS)

    Wang, Tian; Wang, Xiaohui; Song, Tae-Ho; Li, Longtu

    2007-10-01

    Ultrafine-grained ceramics based on barium titanate for base-metal-electrode multilayer ceramic capacitors (BME-MLCCs) applications have been prepared. X-ray diffraction analysis was used to identify the phase compositions of the ceramics. The microstructures were characterized by scanning electron microscopy and transmission electron microscopy. The effects of different dopant contents on the crystal structures, grain growth, microstructures, and dielectric characteristics of the ceramics were investigated. Desired core-shell structures have been observed and the relationships of composition, crystal structure, grain growth, and microstructure have been discussed. The present ceramics show an average grain size of 180 nm and homogeneous microstructures, as well as a high dielectric constant, a low degree of dielectric loss and good X7R temperature characteristics, which would be promising candidates for next-generation BME-MLCC applications.

  19. Synthesis of honeycomb MnO2 nanospheres/carbon nanoparticles/graphene composites as electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Xiong, Yachao; Zhou, Min; Chen, Hao; Feng, Lei; Wang, Zhao; Yan, Xinzhu; Guan, Shiyou

    2015-12-01

    Improving the electrochemical performance of manganese dioxide (MnO2) electrodes is of great significance for supercapacitors. In this study, a novel honeycomb MnO2 nanospheres/carbon nanoparticles/graphene composites has been fabricated through freeze-drying method. The honeycomb MnO2 nanospheres are well inserted and dispersed on the graphene. Carbon nanoparticles in the composites act as spacers to effectively prevent graphene from restacking and agglomeration, construct efficient 3D conducting architecture with graphene for honeycomb MnO2 nanospheres, and alleviate the aggregation of honeycomb MnO2 nanospheres by separating them from each other. As a result, such honeycomb MnO2 nanospheres/carbon nanoparticles/graphene composites display much improved electrochemical capacitive performance of 255 F g-1 at a current density of 0.5 A g-1, outstanding rate capability (150 F g-1 remained at a current density of 20 A g-1) and good cycling stability (83% of the initial capacitance retained after 1000 charge/discharge cycles). The strategy for the synthesis of these composites is very effective.

  20. Synthesis and Characterization of Self-Standing and Highly Flexible δ-MnO2@CNTs/CNTs Composite Films for Direct Use of Supercapacitor Electrodes.

    PubMed

    Wu, Peng; Cheng, Shuang; Yang, Lufeng; Lin, Zhiqiang; Gui, Xuchun; Ou, Xing; Zhou, Jun; Yao, Minghai; Wang, Mengkun; Zhu, Yuanyuan; Liu, Meilin

    2016-09-14

    Self-standing and flexible films worked as pseudocapacitor electrodes have been fabricated via a simple vacuum-filtration procedure to stack δ-MnO2@carbon nanotubes (CNTs) composite layer and pure CNT layer one by one with CNT layers ended. The lightweight CNTs layers served as both current collector and supporter, while the MnO2@CNTs composite layers with birnessite-type MnO2 worked as active layer and made the main contribution to the capacitance. At a low discharge current of 0.2 A g(-1), the layered films displayed a high areal capacitance of 0.293 F cm(-2) with a mass of 1.97 mg cm(-2) (specific capacitance of 149 F g(-1)) and thickness of only 16.5 μm, and hence an volumetric capacitance of about 177.5 F cm(-3). Moreover, the films also exhibited a good rate capability (only about 15% fading for the capacitance when the discharge current increased to 5 A g(-1) from 0.2 A g(-1)), outstanding cycling stability (about 90% of the initial capacitance was remained after 5,000 cycles) and high flexibility (almost no performance change when bended to different angles). In addition, the capacitance of the films increased proportionally with the stacked layers and the geometry area. E.g., when the stacked layers were three times many with a mass of 6.18 mg cm(-2), the areal capacitance of the films was increased to 0.764 F cm(-2) at 0.5 A g(-1), indicating a high electronic conductivity. It is not overstated to say that the flexible and lightweight layered films emerged high potential for future practical applications as supercapacitor electrodes. PMID:27561652

  1. 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. PMID:27287106

  2. 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.

  3. 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.

  4. Electrocatalytic activity of NiO on silicon nanowires with a carbon shell and its application in dye-sensitized solar cell counter electrodes

    NASA Astrophysics Data System (ADS)

    Kim, Junhee; Jung, Cho-Long; Kim, Minsoo; Kim, Soomin; Kang, Yoonmook; Lee, Hae-Seok; Park, Jeounghee; Jun, Yongseok; Kim, Donghwan

    2016-03-01

    To improve the catalytic activity of a material, it is critical to maximize the effective surface area by directly contacting the electrolyte. Nanowires are a promising building block for catalysts in electrochemical applications because of their large surface area. Nickel oxide (NiO) decoration was achieved by drop-casting a nickel-dissolved solution onto vertically aligned silicon nanowire arrays with a carbon shell (SiNW/C). Based on the hybridization of the NiO and silicon nanowire arrays with a carbon shell this study aimed to achieve a synergic effect for the catalytic activity performance. This study demonstrated that the resulting nanomaterial exhibits excellent electrocatalytic activity and performs well as a counter electrode for dye-sensitized solar cells (DSSCs). The compositions of the materials were examined using X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy. Their micro- and nano-structures were investigated using scanning electron microscopy and transmission electron microscopy. The electrochemical activity toward I-/I3- was examined using cyclic voltammetry and electrochemical impedance spectroscopy. The obtained peak power conversion efficiency of the DSSC based on the NiO@SiNW/C counter electrode was 9.49%, which was greater than that of the DSSC based on the Pt counter electrode.To improve the catalytic activity of a material, it is critical to maximize the effective surface area by directly contacting the electrolyte. Nanowires are a promising building block for catalysts in electrochemical applications because of their large surface area. Nickel oxide (NiO) decoration was achieved by drop-casting a nickel-dissolved solution onto vertically aligned silicon nanowire arrays with a carbon shell (SiNW/C). Based on the hybridization of the NiO and silicon nanowire arrays with a carbon shell this study aimed to achieve a synergic effect for the catalytic activity performance. This study demonstrated that the

  5. Applications of magnetically active fibre reinforced composites

    NASA Astrophysics Data System (ADS)

    Etches, Julie; Bond, Ian; Mellor, Philip

    2005-05-01

    As the application of fibre reinforced polymer composites (FRP) becomes more widespread there is a desire to add functionality beyond that of simple mechanical properties in order to facilitate the development of 'smart' materials. For example, the functionality being discussed in this paper is the imparting of significant magnetic properties to a FRP. This can take the form of soft magnetic performance for use in electrical machines or hard magnetic performance for novel forms of sensing or power generation. It has been demonstrated that by using hollow glass fibres as a reinforcement, magnetic material can be introduced into these fibres without significant effects on the structural behaviour of the FRP. The current studies have included the assessment of such a magnetic FRP in a variety of applications. The addition of hard magnetic materials, e.g. magnetite and barium ferrite, has been achieved through the use of nanopowders and the resulting FRP has been assessed for morphing structures applications. The magnitude of magnetic performance that can be currently achieved is controlled by the availability of suitable magnetic materials in fine powder form and the volume of magnetic material which can be incorporated within the fibres.

  6. Interconnection of multichannel polyimide electrodes using anisotropic conductive films (ACFs) for biomedical applications.

    PubMed

    Baek, Dong-Hyun; Park, Ji Soo; Lee, Eun-Joong; Shin, SuJung; Moon, Jin-Hee; Pak, James Jungho; Lee, Sang-Hoon

    2011-05-01

    In this paper, we propose a method for interconnecting soft polyimide (PI) electrodes using anisotropic conductive films (ACFs). Reliable and automated bonding was achieved through development of a desktop thermocompressive bonding device that could simultaneously deliver appropriate temperatures and pressures to the interconnection area. The bonding conditions were optimized by changing the bonding temperature and bonding pressure. The electrical properties were characterized by measuring the contact resistance of the ACF bonding area, yielding a measure that was used to optimize the applied pressure and temperature. The optimal conditions consisted of applying a pressure of 4 kg f/cm(2) and a temperature of 180 °C for 20 s. Although ACF base bonding is widely used in industry (e.g., liquid crystal display manufacturing), this study constitutes the first trial of a biomedical application. We performed a preliminary in vivo biocompatibility investigation of ACF bonded area. Using the optimized temperature and pressure conditions, we interconnected a 40-channel PI multielectrode device for measuring electroencephalography (EEG) signals from the skulls of mice. The electrical properties of electrode were characterized by measuring the impedance. Finally, EEG signals were measured from the mice skulls using the fabricated devices to investigate suitability for application to biomedical devices.

  7. Cytotoxicity evaluation of polymer-derived ceramics for pacemaker electrode applications.

    PubMed

    Grossenbacher, Jonas; Gullo, Maurizio R; Dalcanale, Federico; Blugan, Gurdial; Kuebler, Jakob; Lecaudé, Stéphanie; Tevaearai Stahel, Hendrik; Brugger, Juergen

    2015-11-01

    Ceramics are known to be chemically stable, and the possibility to electrically dope polymer-derived ceramics makes it a material of interest for implantable electrode applications. We investigated cytotoxic characteristics of four polymer-derived ceramic candidates with either electrically conductive or insulating properties. Cytotoxicity was assessed by culturing C2C12 myoblast cells under two conditions: by exposing them to material extracts and by putting them directly in contact with material samples. Cell spreading was optically evaluated by comparing microscope observations immediately after the materials insertion and after 24 h culturing. Cell viability (MTT) and mortality (LDH) were quantified after 24-h incubation in contact with the materials. Comparison was made with biocompatible positive references (alumina, platinum, biocompatible stainless steel 1.4435), negative references (latex, stainless steel 1.4301) and controls (no material present in the culture wells). We found that the cytotoxic properties of tested ceramics are comparable to established reference materials. These ceramics, which are reported to be very stable, can be microstructured and electrically doped to a wide range of conductivity and are thus excellent candidates for implantable electrode applications including pacemakers.

  8. 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.

  9. Application of Composite Mechanics to Composites Enhanced Concrete Structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Gotsis, Pascal K.

    2006-01-01

    A new and effective method is described to design composites to repair damage or enhance the overload strength of concrete infrastructures. The method is based on composite mechanics which is available in computer codes. It is used to simulate structural sections made from reinforced concrete which are typical in infrastructure as well as select reinforced concrete structures. The structural sections are represented by a number of layers through the thickness where different layers are used in concrete, and for the composite. The reinforced concrete structures are represented with finite elements where the element stiffness parameters are from the structural sections which are represented by composite mechanics. The load carrying capability of the structure is determined by progressive structural fracture. Results show up to 40 percent improvements for damage and for overload enhancement with relatively small laminate thickness for the structural sections and up to three times for the composite enhanced select structures (arches and domes).

  10. Life testing of LSM-YSZ composite electrodes under reversing-current operation.

    PubMed

    Hughes, Gareth A; Yakal-Kremski, Kyle; Barnett, Scott A

    2013-10-28

    Durability testing of solid oxide cell electrodes in reversing-current and constant-current operation modes is presented. (La0.8Sr0.2)0.98MnO3-δ-Zr0.84Y0.16O2-γ (LSM-YSZ) symmetric cells were tested at 800 °C in air with current densities of 0.5 and 1.5 A cm(-2), with current cycle periods of 1 and 12 h. A continuous increase in both ohmic and polarization resistance was observed, via Electrochemical Impedance Spectroscopy (EIS), for cells tested with a reversing current of 1.5 A cm(-2), whereas cells tested at 0.5 A cm(-2) showed no measurable resistance increase. The resistance degradation was explained by delamination in the electrode, observed by post-test Scanning Electron Microscopy (SEM), near the interface with the electrolyte for the 1.5 A cm(-2) cells, but not for those tested at 0.5 A cm(-2). Current cycle period also impacted the degradation observed at 1.5 A cm(-2): both the rate of resistance increase and the extent of post-test delamination decreased on going from constant current mode to a 12 h period to a 1 h period. The results indicate that lower current densities and reversing-current operation are desirable to maximize the lifetime of solid oxide cells.

  11. 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. PMID:27203558

  12. Electrochemistry and voltammetric determination of colchicine using an acetylene black-dihexadecyl hydrogen phosphate composite film modified glassy carbon electrode.

    PubMed

    Zhang, Huajie

    2006-05-01

    The electrochemical behavior of colchicine at an acetylene black-dihexadecyl hydrogen phosphate (denoted as AB-DHP) composite film coated glassy carbon electrode (GCE) was investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV). Compared with the poor electrochemical signal at the unmodified GCE, the electrochemical response of colchicine at the AB-DHP film modified GCE was greatly improved, as confirmed from the significant peak current enhancement. The remarkable peak current enhancement indicates that the AB-DHP modified GCE has great potential in the sensitive determination of colchicine. Thus, all the experimental conditions, which influence the electrochemical response of colchicine, were studied and the optimum conditions were achieved. Finally, a sensitive and simple voltammetric method with a good linear relationship in the range of 1.0 x 10(-7) approximately 4.0 x 10(-5) mol/L, was developed for the determination of colchicine. The detection limit of colchicine was also examined and a low value of 4.0 x 10(-8) mol/L for 4-min accumulation was obtained (S/N=3). This electrode was successfully applied to detect colchicine in human urine samples.

  13. 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.

  14. Construction and analytical applications of an extractive electrode sensitive to mercury(I).

    PubMed

    Baiulescu, G E; Ciocan, N

    1977-01-01

    The construction and characteristics of a new type of extractive electrode sensitive to Hg(2+)(2) are described. The performance of the electrode is compared with that of an ion-selective electrode with mercurous dithizonate as the active substance. The Hg(2+)(2) -extractive electrode contains Pd(HDz)(2) in its membrane. Its stability and sensitivity are remarkable. It has been used as indicator electrode for the titration of halides alone and in mixtures, and for determination of mercury(I), mercury(II), silver, and of substances containing or reacting with mercury. The basis of the electrode response is discussed.

  15. Synthesis and Applications of Large Area Graphene-Based Electrode Systems

    NASA Astrophysics Data System (ADS)

    Paul, Rajat Kanti

    Graphene is a single sheet of carbon atoms with outstanding electrical and physical properties and being exploited for applications in electronics, sensors, fuel cells, photovoltaics and energy storage. However, practical designs of graphene-based electrode systems and related experimental implementations are required to realize their widespread applications in nano- to bioelectronics. In this dissertation, different graphene-based electrode systems having metallic and semiconducting properties are synthesized optimizing process conditions. Also realized is the potential of the fabricated electrode systems by applying them in practical applications such as sensor devices and fuel cells. The zero bandgap of semimetal graphene still limits its application as an effective field-effect transistor device or a chemiresistor sensor operating at room temperature. It has been shown theoretically and experimentally that graphene nanoribbons (GNRs) or nanomeshes (GNMs) can attain a bandgap that is large enough for a transistor device, and hence would show high sensitivity to various gaseous species or biomolecules. Large-area mono- and bilayer graphene films are synthesized by a simple chemical vapor deposition (CVD) technique depending on the carbon precursors such as methane, acetylene and ethanol, and the results are compared using optical microscopy (OM), Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM) and x-ray photoelectron spectroscopy (XPS). A simple reactive ion etching (RIE) combined with well-established nanosphere lithography is performed on the synthesized CVD-grown monolayer graphene platform to fabricate large area GNMs with specific dimension and periodicity. The fabricated GNMs chemiresistor sensor devices show excellent sensitivity towards NO2 and NH 3, significantly higher than their film counterparts. The GNM sensor devices exhibit sensitivities of about 4.32%/ppm (parts-per-million) in NO 2 and 0.71%/ppm in NH3 with estimated

  16. 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.

  17. Determination of arsenate in water by anion selective membrane electrode using polyurethane-silica gel fibrous anion exchanger composite.

    PubMed

    Khan, Asif Ali; Shaheen, Shakeeba

    2014-01-15

    Polyurethane (PU)-silica (Si gel) based fibrous anion exchanger composites were prepared by solid-gel polymerization of polyurethane in the presence of different amounts of silica gel. The formation of PU-Si gel fibrous anion exchanger composite was characterized by Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTA), scanning electron microscopy (SEM) and elemental analysis. The membrane having a composition of 5:3 (PU:Si gel) shows best results for water content, porosity, thickness and swelling. Our studies show that the present ion selective membrane electrode is selective for arsenic, having detection limit (1×10(-8)M to 1×10(-1)M), response time (45s) and working pH range (5-8). The selectivity coefficient values for interfering ions indicate good selectivity for arsenate (AsO4(3-)) over interfering anions. The accuracy of the detection limit results was compared by PCA-Arsenomat. PMID:24275475

  18. Determination of arsenate in water by anion selective membrane electrode using polyurethane-silica gel fibrous anion exchanger composite.

    PubMed

    Khan, Asif Ali; Shaheen, Shakeeba

    2014-01-15

    Polyurethane (PU)-silica (Si gel) based fibrous anion exchanger composites were prepared by solid-gel polymerization of polyurethane in the presence of different amounts of silica gel. The formation of PU-Si gel fibrous anion exchanger composite was characterized by Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTA), scanning electron microscopy (SEM) and elemental analysis. The membrane having a composition of 5:3 (PU:Si gel) shows best results for water content, porosity, thickness and swelling. Our studies show that the present ion selective membrane electrode is selective for arsenic, having detection limit (1×10(-8)M to 1×10(-1)M), response time (45s) and working pH range (5-8). The selectivity coefficient values for interfering ions indicate good selectivity for arsenate (AsO4(3-)) over interfering anions. The accuracy of the detection limit results was compared by PCA-Arsenomat.

  19. A Rationally Designed Thymidine-Based Self-Assembled Monolayer on a Gold Electrode for Electroanalytical Applications.

    PubMed

    Datta, Dhrubajyoti; Bera, Raj Kumar; Jana, Saibal; Manna, Bhaskar; Roy, Debayan; Anoop, Anakuthil; Raj, C Retna; Pathak, Tanmaya

    2015-07-01

    A self-assembled monolayer (SAM) of 1-(3,5-epidithio-2,3,5-trideoxy-β-D-threo-pentofuranosyl)thymine (EFT) on a gold electrode was prepared and characterized by Raman spectral and electrochemical measurements. Voltammetric and electrochemical impedance measurements show that the SAM of EFT on a Au electrode impedes the electron-transfer reaction. The SAM of EFT was successfully used for the voltammetric sensing of urate in neutral solution. The coexisting ascorbate anion does not interfere and therefore the EFT-based electrode was able to quantify urate at the micromolar level in the presence of a large excess amount of ascorbate. To demonstrate the practical applications, the amount of urate in two different human serum samples was quantified by using the EFT-based electrode; the results are in good agreement with those determined by the clinical method. DFT calculations show that both ascorbate and urate have noncovalent interactions including hydrogen-bonding interactions with EFT.

  20. Magneto-electric interactions at bending resonance in an asymmetric multiferroic composite: Theory and experiment on the influence of electrode position

    NASA Astrophysics Data System (ADS)

    Sreenivasulu, G.; Qu, P.; Petrov, V. M.; Qu, Hongwei; Srinivasan, G.

    2015-05-01

    In magnetostrictive-piezoelectric bilayers the strength of mechanical strain mediated magneto-electric (ME) interactions shows a resonance enhancement at bending modes. Such composites when operating under frequency modulation at bending resonance have very high ME sensitivity and are of importance for ultrasensitive magnetometers. This report provides an avenue for further enhancement in the ME sensitivity by strategic positioning of the electrodes in the bilayer. We discuss the theory and measurements on the dependence of ME coupling on the position of electrodes in a lead zirconate titanate-permendur bilayer. Samples of effective length L with full electrodes and partial electrodes of length l = L/3 are studied. A five-fold increase in ME voltage coefficient (MEVC) at bending resonance and a 75% increase in low-frequency MEVC are measured as the partial electrode position is moved from the free-end to clamped-end of the bilayer. When the partial electrode is close to the clamped end, the low-frequency and resonance MEVC are 22% and 45% higher, respectively, than for fully electroded bilayer. According to the model discussed here these observations could be attributed to non-uniform stress along the sample length under flexural deformation. Such deformations are stronger at the free-end than at the clamped-end, thereby reducing the stress produced by applied magnetic fields and a reduction in MEVC. Estimates of MEVC are in good agreement with the data.

  1. Bioelectrochemical degradation of urea at platinized boron doped diamond electrodes for bioregenerative applications

    NASA Astrophysics Data System (ADS)

    Nicolau, Eduardo; Gonzalez, Ileana; Nicolau, Eduardo; Cabrera, Carlos R.

    The recovery of potable water from space mission wastewater is critical for the life support and environmental health of crew members in long-term missions. NASA estimates reveal that at manned space missions 0.06 kg/person·day of urine is produced, with urea and various salts as its main components. Current spacecraft water reclamation strategies include the utilization of not only multifiltration systems (MF) and reverse osmosis (RO), but also biological components to deal with crew urine streams. In this research we explore the utilization of urease (EC 3.5.1.5) to convert urea directly to nitrogen by the in-situ utilization of the reaction products, to increase the amount of clean water in future space expeditions. First of all, platinum was electrodeposited on boron doped diamond electrodes by cycling the potential between -0.2 V and 1.0 V in metal/0.5 M H2SO4 solution. SEM images of the electrodes showed a distribution of platinum nanoparticles ranging between 50 nm and 300 nm. The biochemical reaction of urease in nature produces ammonia and carbon dioxide from urea. Based on this, Cyclic Voltammetry experiments of an ammonium acetate solution at pH 10 were performed showing an anodic peak at -0.3 V vs. Ag/AgCl due to the ammonia oxidation. Then, a urease solution (Jack Bean) was poured into the electrochemical cell and subsequent additions of urea were performed with the potential held at -0.3 V in order to promote ammonia oxidation. Chronoamperometry data shows that with more than five urea additions the enzyme still responding by producing ammonia, which is being subsequently oxidized at the electrode surface and producing molecular nitrogen. This research has tremendous applications for future long-term space missions since the reaction byproducts could be used for a biomass subsystem (in-situ resource recovery), while generating electricity from the same process.

  2. 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.

  3. Error compensation of single-qubit gates in a surface-electrode ion trap using composite pulses

    NASA Astrophysics Data System (ADS)

    Mount, Emily; Kabytayev, Chingiz; Crain, Stephen; Harper, Robin; Baek, So-Young; Vrijsen, Geert; Flammia, Steven T.; Brown, Kenneth R.; Maunz, Peter; Kim, Jungsang

    2015-12-01

    The fidelity of laser-driven quantum logic operations on trapped ion qubits tend to be lower than microwave-driven logic operations due to the difficulty of stabilizing the driving fields at the ion location. Through stabilization of the driving optical fields and use of composite pulse sequences, we demonstrate high-fidelity single-qubit gates for the hyperfine qubit of a 171/SUPYb+ ion trapped in a microfabricated surface-electrode ion trap. Gate error is characterized using a randomized benchmarking protocol and an average error per randomized Clifford group gate of 3.6 (3 ) ×10-4 is measured. We also report experimental realization of palindromic pulse sequences that scale efficiently in sequence length.

  4. A facile electrochemical fabrication of hierarchically structured nickel-copper composite electrodes on nickel foam for hydrogen evolution reaction

    NASA Astrophysics Data System (ADS)

    Yin, Zuwei; Chen, Fuyi

    2014-11-01

    A NiCu composite electrode with hierarchical structure has been successfully fabricated by an electrochemical method, which consisted of galvanic replacement reaction (GRR), activation process and cyclic voltammetry (CV) treatment. The three-dimensional (3D) Ni-Cu precursors were prepared firstly by dipping Ni foam into three kinds of different copper ion solutions and identified that CuCl2 is a favorite electrolyte. This may be attributed to the adsorption of chloride ion on copper surface to form the CuCln1-n complex and the hydrolysis of CuCln1-n. After an activation process to reduce the hydrolytic product Cu2O into Cu, a CV treatment was performed to form a hierarchical structure to improve the surface area and to heighten the hydrogen evolution reaction (HER) activity. The optimal number of CV cycles is 3.

  5. Advanced composite applications for sub-micron biologically derived microstructures

    NASA Technical Reports Server (NTRS)

    Schnur, J. M.; Price, R. R.; Schoen, P. E.; Bonanventura, Joseph; Kirkpatrick, Douglas

    1991-01-01

    A major thrust of advanced material development is in the area of self-assembled ultra-fine particulate based composites (micro-composites). The application of biologically derived, self-assembled microstructures to form advanced composite materials is discussed. Hollow 0.5 micron diameter cylindrical shaped microcylinders self-assemble from diacetylenic lipids. These microstructures have a multiplicity of potential applications in the material sciences. Exploratory development is proceeding in application areas such as controlled release for drug delivery, wound repair, and biofouling as well as composites for electronic and magnetic applications, and high power microwave cathodes.

  6. Graphene nanocomposites for electrochemical cell electrodes

    SciTech Connect

    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.

  7. Determination of Anthracene on Ag-Au Alloy Nanoparticles/Overoxidized-Polypyrrole Composite Modified Glassy Carbon Electrodes

    PubMed Central

    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 AgNO3 and HAuCl4 using C6H5O7Na3 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. PMID:22163419

  8. Polypyrrole/hexadecylpyridinium chloride-modified graphite oxide composites: Fabrication, characterization, and application in supercapacitors

    NASA Astrophysics Data System (ADS)

    Feng, Huixia; Wang, Bin; Tan, Lin; Chen, Nali; Wang, Nuoxin; Chen, Baiyi

    2014-01-01

    We report a facile and effective method for synthesizing polypyrrole/modified graphite oxide (PPy/MGO) composites by in situ polymerization. The graphite oxide (GO) is modified with hexadecylpyridinium chloride (CPC) and then composited with PPy. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) results demonstrate that PPy chains may combine with CPC molecule via π-π stacking interaction and the structures of PPy/GO and PPy/MGO composites are completely different. Cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectrum (EIS) tests indicate that, at the current density of 1 A g-1, the specific capacitance and energy density of PPy/MGO are 202 F g-1 and 8.49 Wh kg-1 in three-electrode systems and those are 87 F g-1 and 10 Wh kg-1 in two-electrode systems; the capacitance retention of PPy/MGO is 83.8% after 1000 cycles at a scan rate of 1 A g-1; PPy/MGO also exhibited excellent energy performance from Ragone charts. Based on these properties, the PPy/MGO composites may become a promising material for supercapacitor applications.

  9. Mechanical properties of carbon fiber composites for environmental applications

    SciTech Connect

    Andrews, R.; Grulke, E.

    1996-10-01

    Activated carbon fiber composites show great promise as fixed-bed catalytic reactors for use in environmental applications such as flue gas clean-up and ground water decontamination. A novel manufacturing process produces low density composites from chopped carbon fibers and binders. These composites have high permeability, can be activated to have high surface area, and have many potential environmental applications. This paper reports the mechanical and flow properties of these low density composites. Three point flexural strength tests were used to measure composite yield strength and flexural moduli. Composites containing over 10 pph binder had an adequate yield strength of about 200 psi at activations up to 40% weight loss. The composites were anisotropic, having along-fiber to cross-fiber yield strength ratios between 1.2 and 2.0. The friction factor for flow through the composites can be correlated using the fiber Reynolds number, and is affected by the composite bulk density.

  10. The application of carbon aerogel electrodes to desalination {ampersand} waste treatment

    SciTech Connect

    Farmer, J.C., Tran, T.D., Richardson, J.H., Fix, D.V., May, S.C., Thomson, S.L.

    1997-08-01

    An electrically-regenerated electrosorption process known as carbon aerogel capacitive deionization (CDI) has been developed by Lawrence Livermore National Laboratory (LLNL) for continuously removing ionic impurities from aqueous streams. A salt solution flows through an unobstructed channel formed by numerous pairs of parallel carbon aerogel electrodes. Each electrode has a very high Brunauer-Emmet-Teller (BET) surface area (2.0-5.4 x 1O{sup 6} ft{sup 2} lb{sup -1} or 400-1100) and very low electrical resistivity (< 40 m{omega} cm). Surface areas of 1.3 x 10{sup 7} ft{sup 2} lb{sup -1} (2600 m{sup 2} g{sup -1}) have been achieved activation. After polarization, anions and cations are removed from the electrolyte by the imposed electric field and electrosorbed onto the carbon aerogel. The solution is thus separated into two streams, concentrate and purified water. Based upon this analysis, it is concluded that carbon aerogel CDI may be an energy-efficient alternative to electrodialysis and reverse osmosis for the desalination of brackish water (< 5000 ppm), provided that cell geometries and aerogel properties are carefully tailored for such applications.

  11. Synthesis and characterization of DSSC by using Pt nano-counter electrode: photosensor applications

    NASA Astrophysics Data System (ADS)

    Yahia, I. S.; AlFaify, S.; Al-ghamdi, Attieh A.; Hafez, Hoda S.; EL-Bashir, S.; Al-Bassam, A.; El-Naggar, A. M.; Yakuphanoglu, F.

    2016-06-01

    Pt electrode prepared by chemical method has been employed as counter electrode in dye-sensitized solar cell. TiO2 nanomaterial was deposited on fluorine-doped tin oxide substrate to be used as photoanode. Structure of the TiO2 and Pt films was investigated by atomic force microscope. The effect of illumination intensity on the photovoltaic parameters such as open circuit voltage, short circuit current density, output power, fill factor and efficiency of these cells was investigated in the range 2.5-130 mW/cm-2. The cell efficiency is stable above 70 mW/cm2. The fill factor is almost constant all over the studied range of illumination intensity. Impedance spectroscopy of the studied device as the summary measurements of the capacitance-voltage, conductance-voltage and series resistance-voltage characteristics were investigated in a wide range of frequencies (5 kHz-1 MHz). At low frequencies, the capacitance has positive values with peak around the origin due to the interfaces. At 200 and 300 kHz, the capacitance is inverted to negative with further increasing of the positive biasing voltage. Above 400 kHz, C-V profile shows complete negative behavior. Also, the impedance-voltage and phase-voltage characteristics were investigated. This cell shows a new promising device for photosensor applications due to high sensitivity in low and high illuminations.

  12. High specific surface gold electrode on polystyrene substrate: Characterization and application as DNA biosensor.

    PubMed

    Yang, Zhiliu; Liu, Yichen; Lu, Wei; Yuan, Qingpan; Wang, Wei; Pu, Qiaosheng; Yao, Bo

    2016-05-15

    In the past decades, many efforts have been made to improve the sensitivity and specificity of electrochemical DNA biosensors. However, it is still strongly required to develop disposable and reliable DNA biosensors for wide and practical application. In this article, we reported superior electrochemical properties of an integrated plastic-gold electrode (PGE) fabricated in-house by chemical plating on polystyrene substrate. PGEs were found having extremely high capacity of DNA immobilization compared with gold electrodes fabricated by standard sputtering based photolithography. Unique nano-structured surface was observed on PGEs through morphology techniques, which would to some extend give an explanation to higher capacity of DNA immobilization on PGEs. A probable mechanism of carboxylic acid produced on polystyrene substrate after exposure to UV irradiation was proposed and discussed for the first time. This biosensor was applied to detection and manipulate of DNA hybridization. Detection limit of 7.2×10(-11) M and 1-500 nM of linearity range was obtained.

  13. 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.

  14. Performance and cycle life of carbon- and conductive-based air electrodes for rechargeable Zn-air battery applications

    NASA Astrophysics Data System (ADS)

    Chellapandi Velraj, Samgopiraj

    , the LaNi0.8Co0.2O 3-based electrode was unstable during OER after a short time period, while the LaNi0.8Co0.2O3 and NiCo2O 4-based electrodes were stable. The LaNi0.8Co 0.2O3-based electrodes had reasonable ORR activity but stability during oxygen reduction reaction (ORR) was limited due to the flooding of the electrode caused by the extremely hydrophilic nature of the perovskite electrode. On the contrary, the NiCo2O4-based electrode showed reasonable stability for both ORR and OER even during aggressive cyclic lifetime testing at a higher current density of 50 mA.cm-2 and could be a potential support material to replace carbon in bifunctional air electrodes for rechargeable Zn-air battery applications.

  15. 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.

  16. Nanostructured Si/Sn-Ni/C composite as negative electrode for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Edfouf, Z.; Cuevas, F.; Latroche, M.; Georges, C.; Jordy, C.; Hézèque, T.; Caillon, G.; Jumas, J. C.; Sougrati, M. T.

    2011-05-01

    A nanostructured composite with overall atomic composition Ni0.14Sn0.17Si0.32Al0.037C0.346 has been prepared combining powder metallurgy and mechanical milling techniques for being used as anode material in Li-ion battery. Chemical and structural properties of the nanocomposite have been determined by X-ray diffraction (XRD), 119Sn Transmission Mössbauer Spectroscopy (TMS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composite consists of Si particles with typical size ∼150 nm embedded in a poorly crystallized and complex multielemental matrix. The matrix is composed mostly by Ni3.4Sn4, and disordered carbon. Electrochemical evaluation shows a high reversible capacity of 920 mAh g-1, with reasonable reversible capacity retention (∼0.1% loss/cycle) over 280 cycles.

  17. Electrocatalytic activity of NiO on silicon nanowires with a carbon shell and its application in dye-sensitized solar cell counter electrodes.

    PubMed

    Kim, Junhee; Jung, Cho-long; Kim, Minsoo; Kim, Soomin; Kang, Yoonmook; Lee, Hae-seok; Park, Jeounghee; Jun, Yongseok; Kim, Donghwan

    2016-04-14

    To improve the catalytic activity of a material, it is critical to maximize the effective surface area by directly contacting the electrolyte. Nanowires are a promising building block for catalysts in electrochemical applications because of their large surface area. Nickel oxide (NiO) decoration was achieved by drop-casting a nickel-dissolved solution onto vertically aligned silicon nanowire arrays with a carbon shell (SiNW/C). Based on the hybridization of the NiO and silicon nanowire arrays with a carbon shell this study aimed to achieve a synergic effect for the catalytic activity performance. This study demonstrated that the resulting nanomaterial exhibits excellent electrocatalytic activity and performs well as a counter electrode for dye-sensitized solar cells (DSSCs). The compositions of the materials were examined using X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy. Their micro- and nano-structures were investigated using scanning electron microscopy and transmission electron microscopy. The electrochemical activity toward I(-)/I3(-) was examined using cyclic voltammetry and electrochemical impedance spectroscopy. The obtained peak power conversion efficiency of the DSSC based on the NiO@SiNW/C counter electrode was 9.49%, which was greater than that of the DSSC based on the Pt counter electrode. PMID:27001286

  18. Tetrabutylammonium-modified clay film electrodes: characterization and application to the detection of metal ions.

    PubMed

    Maghear, Adela; Tertiş, Mihaela; Fritea, Luminţa; Marian, Iuliu O; Indrea, Emil; Walcarius, Alain; Săndulescu, Robert

    2014-07-01

    This work describes the preparation and characterization of smectite clay partially exchanged with tetrabutylammonium ions (TBA(+)) and its subsequent deposition onto glassy carbon electrode (GCE) for application to the preconcentration electroanalysis of metal ions (Cd, Pb, and Cu). Such partial exchange of TBA(+) induces the expansion of the interlayer region between the clay sheets (as ascertained by XRD) while maintaining its ion exchange capacity, which resulted in enhanced mass transport rates (as pointed out by electrochemical monitoring of permeability properties of these thin (organo)clay films on GCE). This principle was applied here to the anodic stripping square wave voltammetric analysis of metal ions after accumulation at open circuit. Among others, detection limits as low as 3.6×10(-8)M for copper and 7.2×10(-8)M for cadmium have been achieved.

  19. Tetrabutylammonium-modified clay film electrodes: characterization and application to the detection of metal ions.

    PubMed

    Maghear, Adela; Tertiş, Mihaela; Fritea, Luminţa; Marian, Iuliu O; Indrea, Emil; Walcarius, Alain; Săndulescu, Robert

    2014-07-01

    This work describes the preparation and characterization of smectite clay partially exchanged with tetrabutylammonium ions (TBA(+)) and its subsequent deposition onto glassy carbon electrode (GCE) for application to the preconcentration electroanalysis of metal ions (Cd, Pb, and Cu). Such partial exchange of TBA(+) induces the expansion of the interlayer region between the clay sheets (as ascertained by XRD) while maintaining its ion exchange capacity, which resulted in enhanced mass transport rates (as pointed out by electrochemical monitoring of permeability properties of these thin (organo)clay films on GCE). This principle was applied here to the anodic stripping square wave voltammetric analysis of metal ions after accumulation at open circuit. Among others, detection limits as low as 3.6×10(-8)M for copper and 7.2×10(-8)M for cadmium have been achieved. PMID:24840412

  20. Application of copper-carbon fiber composites to power semiconductor devices

    NASA Technical Reports Server (NTRS)

    Kuniya, Keiichi; Arakawa, Hideo; Sakaue, Tadashi; Minorikawa, Hitoshi; Akeyama, Kenji; Sakamoto, Tatsuji

    1988-01-01

    Copper-carbon composite electrodes are used in a series of power semiconductor devices, i.e., resin molded diodes, button-type diodes, stud-type diodes, power modules, and integrated circuit igniter modules. The properties of these power semiconductor devices compare favorably with those conventional devices using Mo or W electrodes. In thermal fatigue tests, no degradation in the electrical and mechanical characteristics of these devices are observed. The new composite electrode with carbon fibers satisfies all of the major requirements for the electrodes in power semiconductor devices.

  1. Reliability Evaluation of Base-Metal-Electrode Multilayer Ceramic Capacitors for Potential Space Applications

    NASA Technical Reports Server (NTRS)

    Liu, David (Donhang); Sampson, Michael J.

    2011-01-01

    Base-metal-electrode (BME) ceramic capacitors are being investigated for possible use in high-reliability spacelevel applications. This paper focuses on how BME capacitors construction and microstructure affects their lifetime and reliability. Examination of the construction and microstructure of commercial off-the-shelf (COTS) BME capacitors reveals great variance in dielectric layer thickness, even among BME capacitors with the same rated voltage. Compared to PME (precious-metal-electrode) capacitors, BME capacitors exhibit a denser and more uniform microstructure, with an average grain size between 0.3 and 0.5 m, which is much less than that of most PME capacitors. BME capacitors can be fabricated with more internal electrode layers and thinner dielectric layers than PME capacitors because they have a fine-grained microstructure and do not shrink much during ceramic sintering. This makes it possible for BME capacitors to achieve a very high capacitance volumetric efficiency. The reliability of BME and PME capacitors was investigated using highly accelerated life testing (HALT). Most BME capacitors were found to fail with an early avalanche breakdown, followed by a regular dielectric wearout failure during the HALT test. When most of the early failures, characterized with avalanche breakdown, were removed, BME capacitors exhibited a minimum mean time-to-failure (MTTF) of more than 105 years at room temperature and rated voltage. Dielectric thickness was found to be a critical parameter for the reliability of BME capacitors. The number of stacked grains in a dielectric layer appears to play a significant role in determining BME capacitor reliability. Although dielectric layer thickness varies for a given rated voltage in BME capacitors, the number of stacked grains is relatively consistent, typically around 12 for a number of BME capacitors with a rated voltage of 25V. This may suggest that the number of grains per dielectric layer is more critical than the

  2. Mechanical properties of carbon fiber composites for environmental applications

    SciTech Connect

    Andrews, R.; Grulke, E.; Kimber, G.

    1996-12-31

    Activated carbon fiber composites show great promise as fixed-bed catalytic reactors for use in environmental applications such as flue gas clean-up and ground water decontamination. A novel manufacturing process produces low density composites from chopped carbon fibers and binders. These composites have high permeability, can be activated to have high surface area, and have many potential environmental applications. This paper reports the mechanical and flow properties of these low density composites. Three point flexural strength tests were used to measure composite yield strength and flexural moduli. Composites containing over 10 pph binder had an adequate yield strength of about 200 psi at activations up to 40% weight loss. The composites were anisotropic, having along-fiber to cross-fiber yield strength ratios between 1.2 and 2.0. The pressure drop of air through the composites correlated with the gas velocity, and showed a dependence on sample density.

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

    PubMed

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

    2016-12-01

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

  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. 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.

  6. 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.

  7. Synthesis and electronic applications of oxide-metal eutectic composites

    SciTech Connect

    Holder, J. D.; Cochran, J. K.; Hill, D. N.; Chapman, A. T.; Clark, G. W.

    1980-01-01

    A review is given of important developments in the synthesis of oxide-metal eutectic composites and the composite application in the continuing development of field emitters. Known metal oxide-metal binary and ternary eutectic systems are listed. The synthesis, electrical conductivity, thermodynamics, and applications are discussed. (FS)

  8. Application of infrared spectroscopy to monitoring gas insulated high-voltage equipment: electrode material-dependent SF(6) decomposition.

    PubMed

    Kurte, R; Beyer, C; Heise, H M; Klockow, D

    2002-08-01

    Sulfur hexafluoride is a chemically inert gas which is used in gas insulated substations (GIS) and other high-voltage equipment, leading to a significant enhancement of apparatus lifetime and reductions in installation size and maintenance requirements compared to conventional air insulated substations. However, component failures due to aging of the gas through electrical discharges may occur, and on-site monitoring for risk assessment is needed. Infrared spectroscopy was used for the analysis of gaseous by-products generated from electrical discharges in sulfur hexafluoride gas. An infrared monitoring system was developed using a micro-cell coupled to an FTIR spectrometer by silver halide fibers. Partial least-squares calibration was applied by using a limited number of optimally selected spectral variables. Emphasis was placed on the determination of main decomposition products, such as SOF(2), SOF(4), and SO(2)F(2). Besides the different electrical conditions, the material of the plane counter electrode of the discharge chamber was also varied between silver, aluminum, copper, tungsten, or tungsten/copper alloy. For the spark experiments the point electrode was the same material as chosen for the plane electrode, whereas for partial discharges a stainless steel needle was employed. Complementary investigations on the chemical composition within the solid counter electrode material by secondary neutral mass spectrometry (SNMS) were also carried out. Under sparking conditions, the electrode material plays an important role in the decomposition rates of the gas-phase, but no relevant material dependence could be observed under partial discharge conditions. PMID:12185577

  9. Dry electrodes for electrocardiography.

    PubMed

    Meziane, N; Webster, J G; Attari, M; Nimunkar, A J

    2013-09-01

    Patient biopotentials are usually measured with conventional disposable Ag/AgCl electrodes. These electrodes provide excellent signal quality but are irritating for long-term use. Skin preparation is usually required prior to the application of electrodes such as shaving and cleansing with alcohol. To overcome these difficulties, researchers and caregivers seek alternative electrodes that would be acceptable in clinical and research environments. Dry electrodes that operate without gel, adhesive or even skin preparation have been studied for many decades. They are used in research applications, but they have yet to achieve acceptance for medical use. So far, a complete comparison and evaluation of dry electrodes is not well described in the literature. This work compares dry electrodes for biomedical use and physiological research, and reviews some novel systems developed for cardiac monitoring. Lastly, the paper provides suggestions to develop a dry-electrode-based system for mobile and long-term cardiac monitoring applications.

  10. 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.

  11. A clinically applicable approach for detecting spontaneous action potential spikes in amyotrophic lateral sclerosis with a linear electrode array.

    PubMed

    Jahanmiri-Nezhad, Faezeh; Li, Xiaoyan; Barkhaus, Paul E; Rymer, William Z; Zhou, Ping

    2014-02-01

    Examination of spontaneous muscle activity is an important part of the routine electromyogram (EMG) in assessing neuromuscular diseases. The EMG is specifically valuable as a diagnostic test in supporting the diagnosis of amyotrophic lateral sclerosis. High-density surface EMG is a relatively new technique that has until now been used in research but has the potential for clinical application. This study presents a simple high-density surface EMG method for automatic detection of spontaneous action potentials from surface electrode array recordings of patients with amyotrophic lateral sclerosis. To reduce computational complexity while maintaining useful information from the electrode array recording, the multichannel high-density surface EMG was transferred to single-dimensional data by calculating the maximum difference across all channels of the electrode array. A spike detection threshold was then set in the single-dimensional domain to identify the firing times of each spontaneous action potential spike, whereas a spike extraction threshold was used to define the onset and offset of the spontaneous spikes. These data were used to extract the spontaneous spike waveforms from the electrode array EMG. A database of detected spontaneous spikes was thus obtained, including their waveforms, on all channels along with their corresponding firing times. This newly developed method makes use of the information from different channels of the electrode array EMG recording. It also has the primary feature of being simple and fast in implementation, with convenient parameter adjustment and user-computer interaction. Hence, it has good possibilities for clinical application.

  12. 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.

  13. 25th anniversary article: polymer-particle composites: phase stability and applications in electrochemical energy storage.

    PubMed

    Srivastava, Samanvaya; Schaefer, Jennifer L; Yang, Zichao; Tu, Zhengyuan; Archer, Lynden A

    2014-01-15

    Polymer-particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created. In favorable situations, the spatial distribution of these interfaces can be controlled to create new hybrid materials with physical and transport properties inaccessible in their constituents or poorly prepared mixtures. This review surveys progress in the last decade in understanding phase behavior, structure, and properties of nanoparticle-polymer composites. The review takes a decidedly polymers perspective and explores how physical and chemical approaches may be employed to create hybrids with controlled distribution of particles. Applications are studied in two contexts of contemporary interest: battery electrolytes and electrodes. In the former, the role of dispersed and aggregated particles on ion-transport is considered. In the latter, the polymer is employed in such small quantities that it has been historically given titles such as binder and carbon precursor that underscore its perceived secondary role. Considering the myriad functions the binder plays in an electrode, it is surprising that highly filled composites have not received more attention. Opportunities in this and related areas are highlighted where recent advances in synthesis and polymer science are inspiring new approaches, and where newcomers to the field could make important contributions. PMID:24323839

  14. 25th anniversary article: polymer-particle composites: phase stability and applications in electrochemical energy storage.

    PubMed

    Srivastava, Samanvaya; Schaefer, Jennifer L; Yang, Zichao; Tu, Zhengyuan; Archer, Lynden A

    2014-01-15

    Polymer-particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created. In favorable situations, the spatial distribution of these interfaces can be controlled to create new hybrid materials with physical and transport properties inaccessible in their constituents or poorly prepared mixtures. This review surveys progress in the last decade in understanding phase behavior, structure, and properties of nanoparticle-polymer composites. The review takes a decidedly polymers perspective and explores how physical and chemical approaches may be employed to create hybrids with controlled distribution of particles. Applications are studied in two contexts of contemporary interest: battery electrolytes and electrodes. In the former, the role of dispersed and aggregated particles on ion-transport is considered. In the latter, the polymer is employed in such small quantities that it has been historically given titles such as binder and carbon precursor that underscore its perceived secondary role. Considering the myriad functions the binder plays in an electrode, it is surprising that highly filled composites have not received more attention. Opportunities in this and related areas are highlighted where recent advances in synthesis and polymer science are inspiring new approaches, and where newcomers to the field could make important contributions.

  15. 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.

  16. Hydrogeological application of electrical resistivity tomography: Implementing a fixed-electrode strategy

    NASA Astrophysics Data System (ADS)

    Pezeshkpour, Parsa

    The requirements of environmental assessments and of understanding and monitoring in-situ mass and heat processes in porous media have led to the development of geophysical methods for remote mapping and monitoring of contaminant plumes and fluid migration. With the possible exception of seismic approaches, electrical methods known as Electrical Resistivity Tomography (ERT) have become the most widely studied and used for these purposes. Wherever a sufficient contrast in ground resistivity is generated by human or natural processes, monitoring the resistivity structure over time may give insight into these processes. ERT has monitoring applications in processes such as Enhanced Oil Recovery (EOR), Slurry Fracture Injection (SFI), and monitoring transport processes in hydrogeology. A permanent electrode arrangement for long term monitoring removes the effects of Earth's heterogeneity and anisotropy when a process is analyzed as a function of time. As a starting point on the work described in this thesis, ERT data were collected from a Cambridge, Ontario, sand pit before, immediately after and one week following a 11000 liters slurry injection. These measurements verified that ERT could detect changes caused by the injection and later movement of this conductive mixture in the ground. The commercial equipment used for these measurements was not well suited to the tasks, mainly because it was extremely slow. Further, there was a lack of robust and user-friendly three-dimensional modeling software to use as a means of predicting response and---eventually---as the engine of an inversion routine. Finally, it was difficult to analyze the injection situation in terms of how best to place a limited number of surface and borehole electrodes to most effectively monitor the injection fluids. The remainder of the thesis addresses these problems. The first objective was to design and construct a more suitable ERT measurement system. The second objective was to adapt SALTFLOW as

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.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. Electronic supplementary information (ESI) available: SEM image, Raman spectrum and electrochemical characterizations. See DOI: 10.1039/c5nr00584a

  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. Raman spectroscopy for in-situ monitoring of electrode processes

    SciTech Connect

    Varma, R; Cook, G M; Yao, N P

    1982-04-01

    The theoretical and experimental applications of Raman spectroscopic techniques to the study of battery electrode processes are described. In particular, the potential of Raman spectroscopy as an in-situ analytical tool for the characterization of the structure and composition of electrode surface layers at electrode-electrolyte interfaces during electrolysis is examined. It is anticipated that this understanding of the battery electrode processes will be helpful in designing battery active material with improved performance. The applications of Raman spectroscopy to the in-situ study of electrode processes has been demonstrated in a few selected areas, including: (1) the anodic corrosion of lead in sulfuric acid and (2) the anodization and sulfation of tetrabasicleadsulfate in sulfuric acid. Preliminary results on the anodization of iron and on the electrochemical behavior of nickel positive-electrode active material in potassium hydroxide electrolytes are presented in the Appendix.