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Sample records for ceria composite electrodes

  1. Fabrication of copper-ceria hybrid composite electrode for electrocatalytic oxidation of methanol

    Institute of Scientific and Technical Information of China (English)

    LI Jing; LI Lijun; YU Yuting; GAO Yanfang; LIU Jinrong

    2013-01-01

    Copper-ceria hybrid composite electrode prepared by electrochemical co-deposition was examined for their redox process and electrocatalytic activities towards the oxidation of methanol.The structure and morphology of electrodes were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM),respectively.XRD pattern of the copper-ceria hybrid composite electrode exhibited some diffraction peaks of CeO2 and SEM micrograph showed that it was composed of grains and flakes.The energy dispersive spectroscopy (EDS) spectrum of this area also showed the presence of cerium.Cyclic voltammetry,CO stripping and chronoamperometry were performed to characterize electrocatalytic property of the prepared samples.In cyclic voltammetry studies and chronoamperometry,copper-ceria hybrid composite electrode towards oxidation of methanol showed a significantly higher response and long term stability.CO stripping results indicated the facile removal of intermediate poisoning species CO in the presence of CeO2,which was helpful for CO and methanol electro-oxidation.

  2. High-temperature conversion of methane on a composite gadolinia-doped ceria-gold electrode

    DEFF Research Database (Denmark)

    Marina, O.A.; Mogensen, Mogens Bjerg

    1999-01-01

    Direct electrochemical oxidation of methane was attempted on a gadolinia-doped ceria Ce(0.6)Gd(0.4)O(1.8) (CG4) electrode in a solid oxide fuel cell using a porous gold-CG4 mixture as current collector Gold is relatively inert to methane in contrast to other popular SOFC anode materials such as...... observed at the open-circuit potential and low anodic overpotentials seems to be due to thermal methane cracking in the gas phase and on the alumina surfaces in the cell housing. At high anodic overpotentials, at electrode potentials where oxygen evolution was expected to take place, the formation of CO(2...

  3. High-temperature conversion of methane on a composite gadolinia-doped ceria-gold electrode

    DEFF Research Database (Denmark)

    Marina, O.A.; Mogensen, Mogens Bjerg

    1999-01-01

    nickel and platinum. CG4 was found to exhibit a low electrocatalytic activity for methane oxidation as well as no significant reforming activity implying that the addition of an electrocatalyst or cracking catalyst to the CG4 anode is required for SOFC operating on methane. The methane conversion......Direct electrochemical oxidation of methane was attempted on a gadolinia-doped ceria Ce(0.6)Gd(0.4)O(1.8) (CG4) electrode in a solid oxide fuel cell using a porous gold-CG4 mixture as current collector Gold is relatively inert to methane in contrast to other popular SOFC anode materials such as...... observed at the open-circuit potential and low anodic overpotentials seems to be due to thermal methane cracking in the gas phase and on the alumina surfaces in the cell housing. At high anodic overpotentials, at electrode potentials where oxygen evolution was expected to take place, the formation of CO(2...

  4. Lanthanide doped ceria thin films as possible counter electrode materials in electrochromic devices

    CERN Document Server

    Hartridge, A

    2000-01-01

    suitability of these thin films as counter electrodes in electrochromic devices. The final chapter then turns to the electrochemical insertion of lithium into these materials using cyclic voltammetry. All films studied enabled the reversible insertion of lithium with varying potentials and charge capacities without the loss of transmission of light common to other potential counter electrode materials. Certain compositions however, comprising ceria doped with Dy, Y, Nd and Pr, allowed enough lithium insertion (charge capacity) to fulfil the requirements of counter electrode materials in electrochromic devices. These materials are therefore worthy of further study. Crystalline solid solutions of lanthanide doped ceria have long been known for their high ionic conductivity and as such have found applications as oxygen sensors and in solid oxide fuel cells. With advances in preparative techniques over the years, thin films of ceria doped with zirconia and titania have been studied and found to possess the necess...

  5. High Performance Nano-Ceria Electrodes for Solid Oxide Cells

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Martinez Aguilera, Lev; Sudireddy, Bhaskar Reddy

    2016-01-01

    In solid oxide electrochemical cells, the conventional Ni-based fuel-electrodes provide high electrocatalytic activity but they are often a major source of long-term performance degradation due to carbon deposition, poisoning of reaction sites, Ni mobility, etc. Doped-ceria is a promising mixed i...

  6. Electrochemical testing of composite electrodes of (La1−xSrx)sMnO3 and doped ceria in NO-containing atmosphere

    DEFF Research Database (Denmark)

    Werchmeister, Rebecka Maria Larsen; Kammer Hansen, Kent; Mogensen, Mogens Bjerg

    2012-01-01

    The possibility of using electrochemical cells for removal of NO x from an exhaust gas with excess O2 has been examined. (La1−x Sr x ) s MnO3 (LSM) and ceria doped with Pr or Gd were selected as electrode materials and investigated in three-electrode cells. The electrodes were characterised elect...

  7. Characterization of (La1-xSrx)(s)MnO3 and Doped Ceria Composite Electrodes in NOx-Containing Atmosphere with Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Werchmeister, Rebecka Maria Larsen; Kammer Hansen, Kent; Mogensen, Mogens Bjerg

    2010-01-01

    polarization resistance (Rp) when NO or NO2 was present in the atmosphere at low temperatures (300–400°C) than in air. The impedance spectra for electrodes in 1% NO in Ar were dominated by a low frequency arc at high temperatures (500–600°C). This arc seemed to be a type of conversion arc, which is related to......This study used electrochemical impedance spectroscopy (EIS) to characterize composite metal oxide electrodes in atmospheres containing NO, NO2, and O2. Symmetrical cells with electrodes of (La1−xSrx)sMnO3 [(x, s)=(0.15, 0.9) and (0.5, 0.99)] and doped ceria [Ce0.9Gd0.1O2 and Ce1−xGdxO2 (x=0.1, 0.......2)] were subjected to EIS while varying the temperature (from 300 to 600°C), the composition of the atmosphere, and the gas flow. The impedance spectra were fitted to equivalent circuits, and common arcs were identified and sought related to physical and chemical processes. The electrodes had a much lower...

  8. Fast mass interdiffusion in ceria/alumina composite

    DEFF Research Database (Denmark)

    Teocoli, Francesca; Ni, De Wei; Sanna, Simone;

    2015-01-01

    Gadolinium-doped ceria (CGO) presents unique processes at low oxygen partial pressure (pO2 < 1012 atm) and low temperatures (T > 800 C) such as faster mass diffusion, which are not observed in conventional sintering under ambient air conditions. In CGO/Al2O3 composites the resulting effects drive...

  9. Ceria Based Composite Membranes for Oxygen Separation

    DEFF Research Database (Denmark)

    Gurauskis, Jonas; Ovtar, Simona; Kaiser, Andreas;

    2014-01-01

    ; meanwhile the primary role of a secondary phase in this membrane is to compensate the low electronic conductivity of matrix at intended functioning conditions. In this work thin film (15-20 μm) composite membranes based on CGO matrix and LSF electronic conducting phase were fabricated and evaluated...... oxygen fluxes close to 1 ml×min×cm-2 at 900 °C and the oxygen driving force of log pO2=-2. Issues related to processing parameters and new results on performance of these asymmetric geometry CGO/LSF composite membranes will be presented. Figure 1. Cross-section of asymmetric CGO-LSF composite membrane...

  10. Modifications of interface chemistry of LSM–YSZ composite by ceria nanoparticles

    DEFF Research Database (Denmark)

    Knöfel, Christina; Wang, Hsiang-Jen; Thydén, Karl Tor Sune; Mogensen, Mogens Bjerg

    2011-01-01

    crystal structure. Low concentrations of lanthanum and manganese originating from LSM were detected within SDC particles. It was also observed that the relative atomic concentration of strontium increased on the LSM–YSZ surface with increasing amount of SDC nanoparticles. These findings are related to the...... applied nanoparticle impregnation method. It is indicated that interactions between surfactant, nanoparticles, impregnation solution and the LSM–YSZ composite take place which can locally affect the surface and interface chemistry of the investigated materials.......A porous composite electrode LSM–YSZ (lanthanum strontium manganite and yttria stabilized zirconia) was impregnated with different amounts of SDC (samarium substituted ceria) nanoparticles. The materials were investigated with X-ray diffraction, scanning electron microscopy, transmission electron...

  11. The Composite Insertion Electrode

    DEFF Research Database (Denmark)

    Atlung, Sven; Zachau-Christiansen, Birgit; West, Keld;

    1984-01-01

    The specific energy obtainable by discharge of porous insertion electrodes is limited by electrolyte depletion in thepores. This can be overcome using a solid ion conductor as electrolyte. The term "composite" is used to distinguishthese electrodes from porous electrodes with liquid electrolyte...

  12. Preparation and characterization of ceria-zirconia composite for enrichment and identification of phosphopeptides.

    Science.gov (United States)

    Wu, Jian-Hong; Xiao, Kuang; Zhao, Yong; Zhang, Wei-Ping; Guo, Lin; Feng, Yu-Qi

    2010-08-01

    Ceria-zirconia composites at different molar ratios were synthesized. Several methods were used to characterize these composites, including X-ray photoelectron spectroscopy, surface area and surface acid-base property detection. A one-step method for isolation and identification of phosphopeptides from peptide mixture was created using these ceria-zirconia composites. Using tryptic digest of standard phosphorylated protein, we have shown that these enrichment and dephosphorylation activities are effective. The adsorption capacity and catalytic property of ceria-zirconia composites at different molar ratios and calcinated temperatures were studied. In combination with MALDI-TOF-based peptide mass finger printing technique, we have established a method to utilize the enrichment/dephosphorylation dual properties of these ceria-zirconia composites for the analysis of phosphoprotein in nonfat milk successfully. PMID:20574959

  13. Preparation, characterization and photocatalytic activity of a novel composite photocatalyst: Ceria-coated activated carbon

    International Nuclear Information System (INIS)

    In the present work, a novel composite photocatalyst ceria-coated activated carbon (CCAC) was prepared by a facile method. The composite photocatalyst was characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and photocatalytic degradation of 4-chlorophenol (4-CP). A synergy effect for 4-CP degradation was observed because the activated carbon (AC) with strong adsorbent activity provided sites for the adsorption of 4-CP. Then, the adsorbed 4-CP can migrate continuously onto the surface of ceria particles and then degraded at there. Hydroquinone (HQ) and benzoquinone (BQ) were found to be the main intermediates of the photocatalytic 4-CP degradation with ceria or CCAC by HPLC measurement. The results suggested that the same reaction mechanism occurred in the presence of ceria or titania.

  14. Composite Electrodes in Electrochemistry

    Czech Academy of Sciences Publication Activity Database

    Šebková, Světlana; Navrátil, Tomáš; Kopanica, M.

    Galway : National University of Ireland , 2004. s. 72. [International Conference on Electroanalysis /10./. 06.06.2004-10.06.2004, Galway] Keywords : electrochemistry * modern electroanalytical sensors * silver composite electrode Subject RIV: CG - Electrochemistry

  15. Composite carbon foam electrode

    Science.gov (United States)

    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.

  16. Composite Electrodes for Electrochemical Supercapacitors

    OpenAIRE

    Yang QuanMin; Li Jun; Zhitomirsky Igor

    2010-01-01

    Abstract 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 to...

  17. High polishing selectivity ceria slurry for formation of top electrode in spin-transfer torque magnetic random access memory

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Hao [Advanced Semiconductor Materials and Devices Development Center, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Electronics and Communication Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Lim, Jae-Hyung [Advanced Semiconductor Materials and Devices Development Center, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Nanoscale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Park, Jin-Hyung [Advanced Semiconductor Materials and Devices Development Center, Hanyang University, Seoul 133-791 (Korea, Republic of); Park, Jea-Gun, E-mail: parkjgL@hanyang.ac.kr [Advanced Semiconductor Materials and Devices Development Center, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Electronics and Communication Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2012-11-01

    During the formation of the top electrode (T.E.) in spin-transfer torque magnetic random access memory, a slurry with a high polishing rate of SiO{sub 2} and a low polishing rate of metal (T.E. material) is required in the chemical mechanical planarization application area. We used a ceria-based slurry with a polymeric additive to maintain the high polishing rate of SiO{sub 2} while it suppresses the polishing rate of the T.E. material, tantalum and ruthenium. We found ruthenium showed a significantly higher selectivity than tantalum in the ceria-based slurry. X-ray photoelectron spectroscopy was used to investigate the adsorption characteristics of the polymeric additive on the T.E. material. Except for the adsorbed polymeric additive, we found that zeta potential of the T.E. material played a critical role in determining the polishing selectivity of SiO{sub 2}-to-T.E. material. - Highlights: Black-Right-Pointing-Pointer High selective chemical mechanical planarization (CMP) slurry was investigated. Black-Right-Pointing-Pointer The slurry has a high selectivity of SiO{sub 2}-to-metals like tantalum and ruthenium. Black-Right-Pointing-Pointer Spin-transfer-torque magnetic memory requires such high selectivity slurry. Black-Right-Pointing-Pointer Surface zeta potential was used to explain CMP mechanism. Black-Right-Pointing-Pointer tantalum and ruthenium have different rate-determining steps during CMP.

  18. Continuum modeling of size effects on the composition and stresses in nanoparticles of ionic solids with application to ceria

    Science.gov (United States)

    Haftbaradaran, Hamed; Mossaiby, Farshid

    2016-03-01

    Owing to its broad potential applications, nanostructured ceria has been subject of intense investigation in the past few decades. Experiments have demonstrated that various material properties of the nanostructured ionic solids including ceria vary with the feature size. Here, we present a theoretical study of the size effects on the composition, defect concentrations and stresses in free-standing nanoparticles of nonstoichiometric ionic solids. To this end, a continuum model is developed which accounts for the highly nonlinear coupling between mechanical, chemical and electrical driving forces, and their effects on the thermodynamic equilibrium of the defect species. It is demonstrated that the model, once applied to the case of ceria, predicts size-dependent defect concentrations and surface stresses. It is further shown that the theoretical predictions of the size effects on the composition and lattice parameter are in good agreement with the experimental observations.

  19. Electrochemical study of lithiated transition metal oxide composite as symmetrical electrode for low temperature ceramic fuel cells

    OpenAIRE

    Fan, Liangdong; Zhang, Hongjuan; Chen, Mingming; Wang, Chengyang; Wang, Hao; Singh, Manish; Zhu, Bin

    2013-01-01

    In this work, Lithiated NiCuZnOx (LNCZO) composite is synthesized and evaluated as a potential symmetrical electrode for ceria-carbonate composite electrolyte based low temperature ceramic fuel cells. Its crystal structures, the hydrogen oxidation/oxygen reduction electrochemical activities and fuel cell performances are systematically examined on the symmetrical cell configuration. Nano crystallite particles in the form of composite are observed for these oxides. The LNCZO shows relatively h...

  20. Composite Electrodes for Electrochemical Supercapacitors

    Science.gov (United States)

    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.

  1. Composite Electrodes for Electrochemical Supercapacitors

    Directory of Open Access Journals (Sweden)

    Yang QuanMin

    2010-01-01

    Full Text Available Abstract 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.

  2. Microstructural evaluation of ceria-samaria-gadolinia-nickel oxide composite after reduction in hydrogen atmosphere

    International Nuclear Information System (INIS)

    The ceria-samaria-gadolinia-nickel composite (Ni-SGDC), used as Solid Oxide Fuel Cell (SOFC) anode, was obtained by 'in situ' reduction of NiO-SGDC, with composition Ce0,8(SmGd)0,2O1,9/NiO and mass proportion 40:60%. The composite was produced by hydroxides coprecipitation using CTAB surfactant, followed by solvothermal treatment in butanol, calcination at 600 deg C, pressing and sintering at 1350 deg C for 1 h. The composite reduction kinetic was evaluated in a tubular furnace under dynamic atmosphere of 4% H2 /Air, fixing the temperature at 900 deg C and time between 10 and 120 minutes. The microstructural characterization was performed by optical and scanning electron microscopy. The samples were characterized either by X-ray diffraction and density measurements by immersion technique in water. It was verified that the NiO reduced fraction reached values between 80 and 90% and the achieved porosity (about 30%) is acceptable to a good anode performance (author)

  3. Ceria and copper/ceria functional coatings for electrochemical applications: Materials preparation and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Melnik, J.; Fu, X.Z.; Luo, J.L.; Sanger, A.R.; Chuang, K.T. [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2G6 (Canada); Yang, Q.M. [Vale-Inco Technical Services Ltd., Mississauga, Ontario L5K 1Z9 (Canada)

    2010-04-15

    Following preliminary investigations, two electrodeposition techniques (electrophoretic and electrolytic) were selected and adapted for deposition of doped ceria ceramic and copper/doped ceria composite coatings on Ni substrates (foil and foam). The copper/doped ceria composites have potential value as protective functional coatings for current collectors in electrochemical cells including solid oxide fuel sells (SOFC). The doped ceria ceramic coating has potential application as a porous matrix for anodes of SOFCs operating on syngas, sour gas, or hydrocarbons. (author)

  4. Electrospinning of Ceria and Nickel Oxide Nanofibers

    Science.gov (United States)

    Yerasi, Jyothi Swaroop Reddy

    Electrospinning uses an electrical charge to draw very fine fibers from a liquid. It has very high potential for industrial processing. Electrospinning is cost effective, repeatable and it can produce long, continuous nanofibers. Polymers such as polyalcohol, polyamides, and PLLA can be easily electrospun. The increase in demand for clean energy combined with the research work in progress and the potential advantages of electrospun electrodes over conventionally fabricated SOFCs makes electrospinning a strong candidate. In this thesis, ceramic nanofibers (ceria and nickel oxide) that can potentially be used in SOFCs are fabricated. A three-phase approach is implemented in the fabrication of ceria and nickel oxide nanofibers. The first phase involves the preparation of the composite ceramic-polymer solution to be electrospun. The second phase gives the processing conditions such as voltage applied, feed rate, and gauge of syringe tip used for successfully electrospinning composite ceramic-polymer fibers. The final stage demonstrates the temperature cycles used to burn out the polymer and calcine the ceramic particles in the ceramic-polymer nanofibers leaving behind ceria and nickel oxide nanofibers. Techniques such as scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray Diffraction (XRD) were used to measure the average diameter of the fibers formed and to understand the chemical composition and crystallanity of the nanofibers after calcination. This thesis also discusses the advantages and possibility of fabricating side-by-side nanofibers and oriented nanofiber mats.

  5. In situ confocal Raman micro-spectroscopy and electrochemical studies of mussel adhesive protein and ceria composite film on carbon steel in salt solutions

    International Nuclear Information System (INIS)

    Highlights: • Film-forming corrosion inhibitor composed of Mussel protein and CeO2 nanoparticles. • Confocal Raman mapping combined with EIS for studies of inhibition mechanism. • Mussel protein forms tri-Fe3+/catechol complexes and binds to ceria nanoparticles. • The composite film oxidizes ferrous to ferric. • Phosphates react with Fe ions and heal defects of the composite film. -- Abstract: Thin films composed of Mefp-1 and ceria nanoparticles have shown an increasing corrosion inhibition effect with time for carbon steel in acidic aqueous solutions containing phosphate, which motivates a detailed study of the inhibition mechanism by in situ confocal Raman micro-spectroscopy (CRM) and electrochemical impedance spectroscopy (EIS) measurements. The presence of both CeO2 and ferric oxides in the thin composite film was demonstrated by X-ray photoelectron spectroscopy analysis. The Raman spectra assisted by DFT calculations suggest that Mefp-1 forms tri-Fe3+/Mefp-1 complexes and binds to ceria nanoparticles in the composite film. The in situ CRM measurement allow us to follow the development of corrosion products. The measurements show a mixture of Fe oxides/oxyhydroxides, and also indicate that ferrous oxides may be further oxidized by the composite film. Moreover, phosphate ions react with the Fe ions released from the surface to form iron–phosphate deposits, which become incorporated into the corrosion product layer and the composite film. The EIS measurements suggest a layered surface structure formed by the initial Mefp-1/ceria composite layer and the corrosion products/iron–phosphate deposits. These measurements also demonstrate the greatly increased inhibition effect of the composite film in the presence of the phosphate ions. The consistent CRM and EIS results suggest that the iron–phosphate deposits heal defects in the composite film and corrosion product layer, which results in a significantly improved corrosion inhibition of the Mefp-1

  6. Characterization of Pd catalyst-electrodes deposited on YSZ: Influence of the preparation technique and the presence of a ceria interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Borja, Carmen, E-mail: Carmen.JBorja@uclm.es [Departamento de Ingenieria Quimica, Facultad de Ciencias Quimicas, Universidad de Castilla-La Mancha. Avenida Camilo Jose Cela 12, 13071 Ciudad Real (Spain); Matei, Florina [Department of Petroleum Processing Engineering and Environmental Protection, Petroleum - Gas University of Ploiesti (Romania); Dorado, Fernando; Valverde, Jose Luis [Departamento de Ingenieria Quimica, Facultad de Ciencias Quimicas, Universidad de Castilla-La Mancha. Avenida Camilo Jose Cela 12, 13071 Ciudad Real (Spain)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Impregnation of palladium over YSZ led to more dispersed films. Black-Right-Pointing-Pointer XPS spectra indicated electron deficient Pd{sup 2+} species on the surface of palladium films. Black-Right-Pointing-Pointer Impregnated palladium films were more active than those prepared by paste deposition Black-Right-Pointing-Pointer The addition of a CeO{sub 2} interlayer enhanced the catalytic rate for the impregnated samples. - Abstract: Palladium catalyst-electrodes supported on Y{sub 2}O{sub 3}-stabilized-ZrO{sub 2} (YSZ) prepared either by paste deposition or wet impregnation technique were characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found a strong dependence of the catalytic film preparation technique as well as of the presence of a ceria interlayer between the palladium film and the solid electrolyte on the catalytic activity towards methane oxidation. Impregnated palladium films were found to be more active than films prepared by paste deposition. Besides, the addition of ceria allowed stabilizing the palladium active phase for methane oxidation.

  7. Capacitor with a composite carbon foam electrode

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Capacitor with a composite carbon foam electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Steven T. (San Leandro, CA); Pekala, Richard W. (Pleasant Hill, CA); Kaschmitter, James L. (Pleasanton, CA)

    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.

  9. Analytical Application of Silver Composite Electrode

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Kopanica, M.

    2002-01-01

    Roč. 32, č. 2 (2002), s. 153-166. ISSN 1040-8347 R&D Projects: GA ČR GA203/98/P239 Institutional research plan: CEZ:AV0Z4040901 Keywords : silver composite electrode * voltammetry * halogenides Subject RIV: CG - Electrochemistry Impact factor: 2.074, year: 2002

  10. Recent development of ceria-based (nano)composite materials for low temperature ceramic fuel cells and electrolyte-free fuel cells

    OpenAIRE

    Fan, Liangdong; Wang, Chengyang; Chen, Mingming; Zhu, Bin

    2013-01-01

    In the last ten years, the research of solid oxide fuel cells (SOFCs) or ceramic fuel cells (CFC) had focused on reducing the working temperature through the development of novel materials, especially the high ionic conductive electrolyte materials. Many progresses on single-phase electrolyte materials with the enhanced ionic conductivity have been made, but they are still far from the criteria of commercialization. The studies of ceria oxide based composite electrolytes give an alternative s...

  11. Carbon deposition behaviour in metal-infiltrated gadolinia doped ceria electrodes for simulated biogas upgrading in solid oxide electrolysis cells

    Science.gov (United States)

    Duboviks, V.; Lomberg, M.; Maher, R. C.; Cohen, L. F.; Brandon, N. P.; Offer, G. J.

    2015-10-01

    One of the attractive applications for reversible Solid Oxide Cells (SOCs) is to convert CO2 into CO via high temperature electrolysis, which is particularly important for biogas upgrading. To improve biogas utility, the CO2 component can be converted into fuel via electrolysis. A significant issue for SOC operation on biogas is carbon-induced catalyst deactivation. Nickel is widely used in SOC electrodes for reasons of cost and performance, but it has a low tolerance to carbon deposition. Two different modes of carbon formation on Ni-based electrodes are proposed in the present work based on ex-situ Raman measurements which are in agreement with previous studies. While copper is known to be resistant towards carbon formation, two significant issues have prevented its application in SOC electrodes - namely its relatively low melting temperature, inhibiting high temperature sintering, and low catalytic activity for hydrogen oxidation. In this study, the electrodes were prepared through a low temperature metal infiltration technique. Since the metal infiltration technique avoids high sintering temperatures, Cu-Ce0.9Gd0.1O2-δ (Cu-CGO) electrodes were fabricated and tested as an alternative to Ni-CGO electrodes. We demonstrate that the performance of Cu-CGO electrodes is equivalent to Ni-CGO electrodes, whilst carbon formation is fully suppressed when operated on biogas mixture.

  12. Analytical Applications of Composite Solid Electrodes

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Barek, J.

    2009-01-01

    Roč. 39, č. 3 (2009), s. 131-147. ISSN 1040-8347 R&D Projects: GA ČR GA203/07/1195; GA AV ČR IAA400400806; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40400503 Keywords : composite solid electrodes * voltammetry * amperometry * environmental analysis * review Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.621, year: 2009

  13. Composite Electrodes in Environmental Analytical Chemistry

    Czech Academy of Sciences Publication Activity Database

    Barek, J.; Navrátil, Tomáš; Šebková, Světlana; Kopanica, M.

    Praha, 2003 - (Barek, J.; Buszewski, B.; Frak, H.; Ševčík, J.), s. 3-8 ISBN 80-86238-26-1. [Seminar on Environmental Analytical Chemistry /3./. Bayreuth (DE), 15.02.2003] Grant ostatní: GIT(AR) 101/02/U111/CZ Institutional research plan: CEZ:AV0Z4040901 Keywords : composite electrodes * analytical applications Subject RIV: CG - Electrochemistry

  14. Smooth Nanowire/Polymer Composite Transparent Electrodes

    KAUST Repository

    Gaynor, Whitney

    2011-04-29

    Smooth composite transparent electrodes are fabricated via lamination of silver nanowires into the polymer poly-(4,3-ethylene dioxythiophene): poly(styrene-sulfonate) (PEDOT:PSS). The surface roughness is dramatically reduced compared to bare nanowires. High-efficiency P3HT:PCBM organic photovoltaic cells can be fabricated using these composites, reproducing the performance of cells on indium tin oxide (ITO) on glass and improving the performance of cells on ITO on plastic. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    OpenAIRE

    Manea, F.; Motoc, S.; Pop, A.(National Institute for Physics and Nuclear Engineering, Bucharest, Romania); Remes, A.; Schoonman, J.

    2012-01-01

    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.

  16. Improved Internal Reference Oxygen Sensors with Composite Ceramic Electrodes

    DEFF Research Database (Denmark)

    Hu, Qiang; Jacobsen, Torben; Hansen, Karin Vels;

    2012-01-01

    Potentiometric oxygen sensors with an internal reference electrode, which uses the equilibrium pO2 of the binary mixture of Ni/NiO as the reference, are demonstrated. The cells employ Pt or composite ceramics as the sensing electrode. The cells are fabricated by a flexible and potentially low cost...... performance are highly reproducible. The composite ceramics, based on strontium doped manganite and yttria doped zirconia, are proven superior over Pt to serve as the electrode material....

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

    NARCIS (Netherlands)

    Manea, F.; Motoc, S.; Pop, A.; Remes, A.; Schoonman, J.

    2012-01-01

    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 nan

  18. Zirconia-ceria solid solution synthesis and the temperature-time-transformation diagram for the 1:1 composition

    International Nuclear Information System (INIS)

    Zirconia-ceria solid solutions of tetragonal symmetry (t'-ZrO2) containing 30 to 65 mol% ceria were prepared by annealing c'-ZrO2 at 627C samples sintered at 1,660-1,760C, where c'-ZrO2 is defined as a cubic or tetragonal phase whose axial ratio c/a (tetragonality) is equal to 1. The lattice parameters and the cube root of the unit cell volumes of the annealed samples increased linearly with the ceria content but, on the other hand, the axial ratio c/a (tetragonality) decreased to 1.000 at 70 mol%. During the annealing of each sample, the cell volume decreased because the residual Ce3+ ions were oxidized to the smaller Ce4+. The temperature-time-transformation (TTT) diagram of the 1:1 solid solution was investigated for the c' - t' diffusionless phase transition and the c'- (t + c) diffusional reaction. The c' - t' transformation was found to behave as a thermally activated process with an activation energy estimated to be 113 kJ/mol. This value may indicate that c' - t' transformation is controlled by oxygen diffusion accompanied by dimensional changes of the cerium ions

  19. Arsenic(III) adsorption from aqueous solutions on novel carbon cryogel/ceria nanocomposite

    OpenAIRE

    Tamara Minović Arsić; Ana Kalijadis; Branko Matović; Milovan Stoiljković; Jelena Pantić; Jovan Jovanović; Rada Petrović; Bojan Jokić; Biljana Babić

    2016-01-01

    Carbon cryogel/ceria composite, with 10 wt.% of ceria, was synthesized by mixing of ceria and carbon cryogel (CC). The sample was characterized by field emission scanning electron microscopy, nitrogen adsorption and X-ray diffraction. The adsorption of arsenic(III) ions from aqueous solutions on carbon cryogel/ceria nanocomposite was studied as a function of time, solution pH and As(III) ion concentration. The results are correlated with previous investigations of adsorption mechanism of arse...

  20. Kinetic Studies on Ni-YSZ Composite Electrodes

    DEFF Research Database (Denmark)

    Njodzefon, Jean-Claude; Sudireddy, Bhaskar Reddy; Hjelm, Johan; Graves, Christopher R.

    2015-01-01

    AC and DC techniques were applied to investigate the electrochemical reaction kinetics of porous composite Ni/8-mol% yttria-stabilized zirconia (Ni/8YSZ) solid oxide cell (SOC) electrodes using a novel pseudo-3-electrode cell geometry. From OCV impedance spectra an activation energy Ea of 1.13 eV...

  1. Compliant composite electrodes and large strain bistable actuation

    Science.gov (United States)

    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.

  2. Development and characterization of a new conducting carbon composite electrode

    International Nuclear Information System (INIS)

    A new conducting composite flexible material prepared from cellulose acetate (CA) polymer and graphite has been developed and used for the fabrication of electrodes, which were then characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy (SEM) was used to provide information concerning the morphology of the composite electrode surface. The potential window, background currents and capacitance were evaluated by cyclic voltammetry in the pH range from 4.6 to 8.2. The voltammetry of model electroactive species demonstrates a close to reversible electrochemical behaviour, under linear diffusion control. The electroactive area of the composite electrodes increases after appropriate electrode polishing and electrochemical pre-treatment. The electrodes were used as substrate for the electropolymerisation of the phenazine dye neutral red, for future use as redox mediator in electrochemical biosensors. The composite electrodes were also successfully used for the amperometric detection of ascorbate at 0.0 V vs. SCE, and applied to the measurement of ascorbate in Vitamin C tablets; the sensor exhibits high sensitivity and a low detection limit of 7.7 μM. Perspectives for use as a versatile, mechanically flexible and robust composite electrode of easily adaptable dimensions are indicated

  3. Transparent composite electrode for high-efficiency polymer LEDs

    Science.gov (United States)

    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%.

  4. Manganese oxide composite electrodes for lithium batteries

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2016-05-01

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

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

    Science.gov (United States)

    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. Kinetic Studies on Ni-YSZ Composite Electrodes

    DEFF Research Database (Denmark)

    Njodzefon, Jean-Claude; Hjelm, Johan; Graves, Christopher R.;

    2015-01-01

    carefully chosen cell geometry, methodology and operation conditions. Experimental The investigated cells consist of porous Ni/8YSZ composite working-electrodes with an active area between 0.8 and 1 mm2 and ~100 mm2 counter electrodes of the same material screen-printed on a special shaped 8YSZ electrolyte......Introduction Polarization of the Solid Oxide Cell (SOC) causes current to flow. If the fuel electrode is anodically polarized, the cell operates in fuel cell mode, oxidizing a fuel like hydrogen, carbon monoxide or hydrocarbons. In cathodic polarization the cell operates in electrolysis mode......, reducing steam, carbon dioxide or both at the fuel electrode. Independent of polarization direction, the current flowing through the electrodes of an SOC is limited by processes such as adsorption and desorption of reactants or products, diffusion through the porous electrodes, activation or charge...

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

    Science.gov (United States)

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

    2016-02-10

    Battery electrodes are complex mesoscale systems comprised of electroactive components, conductive additives, and binders. In this report, methods for processing electrodes with dispersion of the components are described. To investigate the degree of material dispersion, a spin-coating technique was adopted to provide a thin, uniform layer that enabled observation of the morphology. Distinct differences in the distribution profile of the electrode components arising from individual materials physical affinities were readily identified. Hansen solubility parameter (HSP) analysis revealed pertinent surface interactions associated with materials dispersivity. Further studies demonstrated that HSPs can provide an effective strategy to identify surface modification approaches for improved dispersions of battery electrode materials. Specifically, introduction of surfactantlike functionality such as oleic acid (OA) capping and P3HT-conjugated polymer wrapping on the surface of nanomaterials significantly enhanced material dispersity over the composite electrode. The approach to the surface treatment on the basis of HSP study can facilitate design of composite electrodes with uniformly dispersed morphology and may contribute to enhancing their electrical and electrochemical behaviors. The conductivity of the composites and their electrochemical performance was also characterized. The study illustrates the importance of considering electronic conductivity, electron transfer, and ion transport in the design of environments incorporating active nanomaterials. PMID:26765041

  9. Polyaniline-graphite composite film glucose oxidase electrode

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hai-hui; CHEN Hong; CHEN Jin-hua; KUANG Ya-fei

    2006-01-01

    A novel polyaniline-graphite composite film glucose oxidase (PGCF GOD) electrode was developed. The PGCF was synthesized by cyclic voltammetry method in 0.5 mol/L H2SO4 solution containing 1 g/L graphite powder and 0.2 mol/L aniline. The PGCF GOD electrode was prepared by doping GOD into the composite film. The morphology of the PGCF and the response property of the PGCF GOD electrode were investigated by scanning electron microscopy and electrochemical measurement,respectively. The results show that the PGCF has a porous and netty structure and the PGCF GOD electrode has excellent response property such as high sensitivity and short response time. Influences of pH value, temperature, glucose concentration and potential on the response current of the electrode were also discussed. The sensor has a maximum steady-state current density of 357.17 tA/cm2and an apparent Michaelis-Menten constant of 16.57 mmol/L. The maximum current response of the enzyme electrode occurs under the condition of pH 5.5, 0.8 V and 65 ℃.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, Sagar; Lokesh, K.S.; Sampath, S. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012 (India)

    2008-12-01

    The performance of exfoliated graphite (EG)-ruthenium oxide (RuO{sub x}) composites as binderless electrodes is evaluated for electrochemical capacitors (ECs). A composite of EG-RuO{sub 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{sub 2}SO{sub 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{sub x}. (author)

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

    Science.gov (United States)

    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.

  12. Development of graphite-polymer composites as electrode materials

    Directory of Open Access Journals (Sweden)

    Carolina Maria Fioramonti Calixto

    2007-06-01

    Full Text Available Graphite powder was mixed to polyurethane, silicon rubber and Araldite® (epoxy in order to prepare composite materials to be used in the preparation of electrodes. Results showed that voltammetric response could be obtained when at least 50% of graphite (w.w-1 is present in the material. SEM and thermogravimetry were also used in the characterization of the composites.

  13. Anodic Stripping Voltammetry for Arsenic Determination on Composite Gold Electrode

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Kopanica, M.; Krista, J.

    2003-01-01

    Roč. 48, č. 2 (2003), s. 265-272. ISSN 0009-2223 Grant ostatní: GIT(AR) 101/02/U111/CZ Institutional research plan: CEZ:AV0Z4040901 Keywords : arsenic determination * stripping voltammetry * composite gold electrode Subject RIV: CG - Electrochemistry Impact factor: 0.415, year: 2003

  14. Stabilizing dimensional changes in Si-based composite electrodes by controlling the electrode porosity: An in situ electrochemical dilatometric study

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Goojin [Green Energy System Center, Kumoh National Institute of Technology, Gumi, Gyeongbuk 730-701 (Korea, Republic of); Lee, Sang Min; Choi, Nam Soon [Battery Development Team, Samsung SDI Co., Ltd. Cheonan, Chungnam 330-300 (Korea, Republic of); Kim, Young-Ugk, E-mail: kyuang@snu.ac.kr [Battery Development Team, Samsung SDI Co., Ltd. Cheonan, Chungnam 330-300 (Korea, Republic of); Lee, Churl Kyoung [School of Advanced Materials and System Engineering, Kumoh National Institute of Technology, Gumi, Gyeongbuk, 730-701 (Korea, Republic of)

    2011-05-30

    Highlights: > A porosity-controllable Si-based composite electrode was fabricated. > PMMA showing unzipping phenomena was utilized as a pore-forming agent. > Cyclic dilation behavior was investigated with an in situ electrochemical dilatometry. > PMMA-treated electrodes exhibited improved cycle performance. > Control of electrode porosity by PMMA can be an effective way for Si-based electrodes. - Abstract: A porosity-controllable Si-based composite electrode was fabricated in the present study. Poly(methyl methacrylate) (PMMA), which possesses the unique thermal property of unzipping, was utilized as a pore-forming agent during electrode fabrication. PMMA-treated electrodes presented relatively low volume expansion and little deformation during lithiation. The cyclic dilation behavior of PMMA-treated electrodes was investigated by applying an in situ electrochemical dilatometric method, and enhanced dimensional reversibility during cycling was observed. The dilation behavior was closely related to the electrochemical performance, and PMMA-treated electrodes exhibited improved capacity retention and low impedance change during cycling. The newly generated pores in the PMMA-treated electrode can accommodate the volumetric expansion of Si-based active materials, which suppresses electrode deformation and the breakdown of the electrical network. The porosity plays an important role in Si-based electrodes. Thus, controlling the porosity through PMMA-treatment can be an effective way for the application of Si-based composite electrodes for advanced lithium-ion batteries.

  15. Raman and Rietveld structural characterization of sintered alkaline earth doped ceria

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira Junior, Jose Marcio; Brum Malta, Luiz Fernando; Garrido, Francisco M.S. [Departamento de Quimica Inorganica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 149, Centro de Tecnologia, Bloco A, room 632, CEP 68563, 21941-909 Rio de Janeiro, RJ (Brazil); Ogasawara, Tsuneharu [Programa de Engenharia Metalurgica e de Materiais, Coordenacao dos Programas de Pos - Graduacao de Engenharia, Centro de Tecnologia, Universidade Federal do Rio de Janeiro, Ilha do Fundao, CEP 68505, 21941-972 Rio de Janeiro, RJ (Brazil); Medeiros, Marta Eloisa, E-mail: chico@iq.ufrj.br [Departamento de Quimica Inorganica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 149, Centro de Tecnologia, Bloco A, room 632, CEP 68563, 21941-909 Rio de Janeiro, RJ (Brazil)

    2012-08-15

    Nanocrystalline calcium and strontium singly doped ceria and co-doped ceria materials for solid electrolytes were prepared via a hydrothermal route. The effect of the hydrothermal treatment time on the solid solution composition was evaluated. Sr doped ceria was the most difficult to form, due to the Sr{sup 2+} large ionic radius. The small crystal size (12-16 nm) of powders allowed sintering into dense ceramic pellets at 1350 Degree-Sign C for 5 h. Raman spectroscopy evidenced a great lattice distortion for Sr doped and co-doped ceria materials, explaining the deterioration of the electrical properties for these ceramics. Besides that, a second phase was detected for Sr doped ceria pellet by using X-ray powder diffraction and Rietveld refinement of XRD data. Impedance measurements showed that Ca-doped ceria behaves as the best ionic conductor ({sigma}{sub g} 390 Degree-Sign C = 1.0 Multiplication-Sign 10{sup -3} S cm{sup -1}) since the nominal composition was achieved; on the other hand, Sr doped ceria performed as resistive materials since Sr incorporation into ceria lattice was critical. These results enhance the close interlace between electrical performance and chemical composition of alkaline earth doped ceria. -- Highlights: Black-Right-Pointing-Pointer Hydrothermally synthesized calcium doped ceria nanoparticles. Black-Right-Pointing-Pointer Incorporation of alkaline earth dopant into ceria lattice. Black-Right-Pointing-Pointer Raman and Rietveld structural characterization. Black-Right-Pointing-Pointer Calcium doped ceria ceramic pellets with high ionic conductivity. Black-Right-Pointing-Pointer Problems associated with the Sr{sup 2+} incorporation into ceria lattice.

  16. Metal Oxide/Graphene Composites for Supercapacitive Electrode Materials.

    Science.gov (United States)

    Jeong, Gyoung Hwa; Baek, Seungmin; Lee, Seungyeol; Kim, Sang-Wook

    2016-04-01

    Graphene composites with metal or metal oxide nanoparticles have been extensively investigated owing to their potential applications in the fields of fuel cells, batteries, sensing, solar cells, and catalysis. Among them, much research has focused on supercapacitor applications and have come close to realization. Composites include monometal oxides of cobalt, nickel, manganese, and iron, as well as their binary and ternary oxides. In addition, their morphological control and hybrid systems of carbon nanotubes have also been investigated. This review presents the current trends in research on metal oxide/graphene composites for supercapacitors. Furthermore, methods are suggested to improve the properties of electrochemical capacitor electrodes. PMID:27061763

  17. Surface modification of ceria nanoparticles and their chemical mechanical polishing behavior on glass substrate

    International Nuclear Information System (INIS)

    To improve their chemical mechanical polishing (CMP) performance, ceria nanoparticles were surface modified with γ-aminopropyltriethoxysilane (APS) through silanization reaction with their surface hydroxyl group. The compositions, structures and dispersibility of the modified ceria particles were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), laser particle size analyzer, zeta potential measurement and stability test, respectively. The results indicated that APS had been successfully grafted onto the surface of ceria nanoparticles, which led to the modified ceria nanoparticles with better dispersibility and stability than unmodified ceria particles in aqueous fluids. Then, CMP performance of the modified ceria nanoparticles on glass substrate was investigated. Experimental results showed that the modified ceria particles exhibited lower material removal rate (MRR) but much better surface quality than unmodified ceria particles, which may be explained by the hardness reduction of ceria particles, the enhancement of lubrication of the particles and substrate surfaces, and the elimination of the agglomeration among the ceria particles.

  18. Anodic stripping voltammetry using graphite composite solid electrode

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Barek, J.; Kopanica, Miloslav

    2009-01-01

    Roč. 74, 11-12 (2009), s. 1807-1826. ISSN 0010-0765 R&D Projects: GA AV ČR IAA400400806; GA ČR GA203/07/1195; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40400503 Keywords : Graphite composite solid electrode * voltammetry * metals Subject RIV: CG - Electrochemistry Impact factor: 0.856, year: 2009

  19. Sintering behavior of ceria pellets

    Energy Technology Data Exchange (ETDEWEB)

    Abd El-Halim, A.S.; Abdelmonem, N.M.; Abd El-Hamid, G.; Afify, N.A.

    1989-02-01

    The sintering behaviour of ceria pellets was studied to produce dense, sound and crack-free pellets. Ceria is prepared by the precipitation of ammonium cerous carbonate (ACeC). The precipitate of ACeC is dried and then calcined to produce ceria (CeO/sub 2/) powder. The ceria powder is used to fabricate pellets which are sintered at 1200...1500/sup 0/C. It was found that higher density (more than 85% of the theoretical), sound and crack-free ceria pellets can be obtained via calcination of ACeC powders at 600/sup 0/C for 2 h, pressing the obtained ceria powders into pellets at 550 N/mm/sup 2/, and then sintering these pellets at 1500/sup 0/C for 3 h in air.

  20. Ruthenium oxide-niobium hydroxide composites for pseudocapacitor electrodes

    International Nuclear Information System (INIS)

    A simple solution-based method has been developed to vary the composition of redox active ruthenium oxide with highly proton-conducting niobium hydroxide to create stable, high capacitance electrodes at elevated temperatures. This method presents a dramatic departure from most other ruthenium oxide systems, which are prepared through annealing of hydrous ruthenium oxide. Typically RuO2 processed at high temperature only exhibits high electrical conductivity and suffers from poor proton conduction, giving low overall capacitances. Here, the optimized Ru/Nb oxide composition can be used to achieve high power densities, high capacitances, and stabilized electrodes while significantly reducing ruthenium content. Extensive materials characterization including high-resolution cross-sectional TEM, elemental mapping, XRD, electrochemical impedance spectroscopy, and proton NMR were used to evaluate the structure of the material system. The electrochemically inert niobium oxide serves as a network former enhancing accessibility to redox active ruthenium oxide. The dispersion of RuO2 in the NbO(OH)x matrix results in reduced RuO2 particle size, as observed via TEM and XRD, while also increasing the proton concentration in the material. Interconnected RuO2 particles provide electrically conducting pathways, even at low Ru contents, where percolation networks remain intact. Ruthenium is more efficiently utilized in the Ru/Nb composites and ruthenium content can be significantly reduced without decreasing capacitive performance. In addition, the composite electrodes, with the fine mixing of Ru and Nb, give higher power performance than for RuO2 alone.

  1. Composite oxygen electrode and method for preparing same

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention provides a composite oxygen electrode, comprising - a porous backbone structure comprising two separate but percolating phases, the first phase being an electronic conducting phase, the second phase being an oxide ion conducting phase; and - an electrocatalytic layer on the...... the steps of: - forming a porous backbone structure comprising two separate but percolating phases, the first phase being an electronic conducting phase, the second phase being an oxide ion conducting phase; and - applying an electrocatalytic layer on the surface of said backbone structure, wherein...

  2. Patch electrode glass composition affects ion channel currents.

    OpenAIRE

    Furman, R E; Tanaka, J C

    1988-01-01

    The influence of patch electrode glass composition on macroscopic IV relations in inside-out patches of the cGMP-activated ion channel from rod photoreceptors was examined for a soda lime glass, a Kovar sealing glass, a borosilicate glass, and several soft lead glasses. In several glasses the shape or magnitude of the currents changed as the concentration of EGTA or EDTA was increased from 200 microM to 10 mM. The changes in IV response suggest that, at low concentrations of chelator, divalen...

  3. The pH-dependant attachment of ceria nanoparticles to silica using surface analytical techniques

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • A model for interaction between ceria nanoparticles and silica surfaces is proposed. • Proposed model investigated using zeta potential measurements and XPS. • Surface contamination is minimized at higher slurry pH levels. • High-resolution Ce 3d XPS and surface composition measured at different pH levels. • Variations in ceria contamination on silica surfaces via SEM and AES are studied. - Abstract: The adhesion and removal of ceria particles to a silica surface was investigated with the use of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and auger electron spectroscopy (AES) measurements. A model is presented based on electrophoretic mobility measurements of ceria slurry and silica particles at different pH's. XPS results show that at acidic pH values, ceria is present on silica surfaces, but at alkaline pH values, far less ceria is present, or no ceria is present in the extreme case. SEM results corroborated the XPS results showing uniform distribution of ceria particles on silica surface at pH 6 while a clean silica surface is observed at pH 12. However, SEM images show agglomeration of ceria particles occurring at the isoelectric point of ceria at ∼pH 9.6. High resolution Ce 3d XPS analysis indicates that ceria present on the surface is composed ∼31% Ce(III) and ∼69% Ce(IV). AES mapping done at specific points on the silica surface validated both XPS and SEM results. Based on XPS, SEM and AES analyses, it is clear that an alkaline pH is necessary to minimize particulate contamination of silica surface by ceria

  4. Carbon nanotube/felt composite electrodes without polymer binders

    Energy Technology Data Exchange (ETDEWEB)

    Rosolen, J. Mauricio; Matsubara, E.Y.; Marchesin, Marcel S.; Lala, Stella M.; Montoro, L.A.; Tronto, S. [Departamento de Quimica-FFCLRP, Universidade de Sao Paulo, Ribeirao Preto 14040-930, SP (Brazil)

    2006-11-08

    In this work we have investigated the suitability of composite electrodes consisting of cup-stacked and bamboo-like carbon nanotubes (CNT) synthesized directly onto a carbon felt for both lithium storage and double-layer capacitance applications. The CNT/felt composite electrode was prepared using catalytic chemical vapor decomposition on the carbon felt. The microstructure of the electrodes was characterized by scanning electron microscopy. Electrochemical characterization of the CNT/felt, either submitted or not to acid treatment for extraction of the catalytic particles used during the CNT growth, was carried out using 1molL{sup -1} LiPF{sub 6} in mixtures of ethylene carbonate, dimethyl carbonate, diethyl carbonate, and propylene carbonate. The carbon nanotubes loading and the type of CNT, whether open or closed, on the felt were the most significant factors regarding the electrochemical properties of the composite. With respect to the application of the composite to lithium storage, an anomalous behavior in the reversible specific capacity as a function of the current was detected. The capacity was found to be large at higher current values. The best reversible specific capacity was found for the open-CNT/felt (275mAhg{sup -1} at 0.16Ag{sup -1}, and 200mAhg{sup -1} at 0.82Ag{sup -1}), on an area of 0.634mm{sup 2}. The double-layer capacitance of the CNT decreased with increasing current. In the case of the open-CNT with a CNT loading of 13.93mg, the composite provided 40.3{mu}Fcm{sup 2} or about 12Fg{sup -1} at 10mA of polarization current using 1molL{sup -1} LiPF{sub 6} in mixtures of ethylene carbonate and dimethyl carbonate. For the closed-CNT with a CNT loading of 9.3mg, the double-layer capacitance was 30Fg{sup -1} at 20mA in 1M H{sub 2}SO{sub 4}. (author)

  5. Conducting polymer/carbon nanocoil composite electrodes for efficient supercapacitors

    KAUST Repository

    Baby, Rakhi Raghavan

    2012-01-01

    Herein, we report for the first time, conducting polymer (polyaniline (PANI) and polypyrrole (PPY)) coated carbon nanocoils (CNCs) as efficient binder-free electrode materials for supercapacitors. CNCs act as a perfect backbone for the uniform distribution of the conducting polymers in the composites. In two electrode configuration, the samples exhibited high specific capacitance with the values reaching up to 360 and 202 F g -1 for PANI/CNCs and PPY/CNCs respectively. The values obtained for specific capacitance and maximum storage energy per unit mass of the composites were found to be comparable to one of the best reported values for polymer coated multi-walled carbon nanotubes. In addition, the fabricated PANI/CNC based supercapacitors exhibited a high value of 44.61 Wh kg -1 for maximum storage energy per unit mass. Although the devices exhibit an initial capacitance loss due to the instability of the polymer, the specific capacitance stabilizes at a fixed value after 500 charge-discharge cycles. © 2012 The Royal Society of Chemistry.

  6. Composite Material Suitable for Use as Electrode Material in a SOC

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to composite material suitable for use as an electrode material in a solid oxide cell, said composite material consist of at least two non-miscible mixed ionic and electronic conductors. Further provided is a composite material suitable for use as an electrode materi...

  7. Expansion and shrinkage of the sulfur composite electrode in rechargeable lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    He, Xiangming; Ren, Jianguo; Wang, Li; Pu, Weihua; Jiang, Changyin; Wan, Chunrong [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)

    2009-05-01

    The expansion and shrinkage characteristics of sulfur composite cathode electrode in rechargeable lithium batteries have been investigated. It was found that the sulfur composites electrodes expanded when discharging and shrank when charging again. The thickness change of the electrode was measured to be about 22%. The thickness of lithium metal anodes was also changed when lithium deposition and dissolution, while the sulfur composites electrodes expanded and shrank conversely. The investigation showed that the thickness changes of lithium anode and sulfur composite cathode could be compensated with each other to keep the total thickness of the cell not to change so much. (author)

  8. The negative effect of ceria on the propene selectivity for isopropanol decomposition over phosphated and phosphate-free ceria/alumina catalysts

    OpenAIRE

    Khalaf, Hussein A

    2013-01-01

    Consequences of loading level of ceria (5, 10 and 20-wt%) on the structural, textural and surface acid–base properties as well as the impacts on catalytic activity towards isopropanol decomposition on pure and phosphated alumina is described. The obtained results indicated that composites mainly kept γ–alumina structure and the addition of ceria and/or phosphate has no effect on the bulk structure of alumina. Textural characteristics show that the phosphated composites have higher surface are...

  9. Monitoring drilling mud composition using flowing liquid junction electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Jasinski, R.; Fletcher, P.; Vercaemer, C.

    1990-06-27

    The concentration of a chosen ionic component of a drilling mud is determined from the potential difference between an ion selective electrode, selective to the component and a reference electrode, the reference electrode being connected to the mud by a liquid junction through which reference electrolyte flows from the electrode to the mud. The system avoids errors due to undesirable interactions between the mud and the reference electrode materials. (author).

  10. Platinum nanophase electro catalysts and composite electrodes for hydrogen production

    Science.gov (United States)

    Petrik, L. F.; Godongwana, Z. G.; Iwuoha, E. I.

    Nanophase Pt electro catalysts were prepared by impregnating a Pt salt containing solution upon a high surface area hexagonal mesoporous silica (HMS) matrix, which was then carbonized to varying degree by chemical vapour deposition of liquid petroleum gas (LPG). Thereafter the HMS Si matrix could be removed by chemical etching with NaOH to immediately form a Pt containing carbon analogue or ordered mesoporous carbon (OMC) with a porous structure similar to the parent HMS. Nanoparticles of Pt electro catalysts were thus successfully stabilized without agglomeration on both HMS and upon the porous HMS carbon analogue or OMC, which was graphitic in nature. The catalysts were electro active for the hydrogen evolution reaction and their activity compared favourable with an industry standard. Such nanophase Pt electro catalysts could be incorporated successfully in a composite electrode by sequential deposition, upon a suitable substrate and the catalysts in electrodes so formed proved to be stable and active under high-applied potential in high electrolyte environment for hydrogen production by electrolysis of water. This route to preparing a nanophase Pt OMC catalyst may be applicable to prepare active electro catalysts for polymer electrolyte fuel cells and solid polymer electrolyte electrolyzers.

  11. Development of new metal matrix composite electrodes for electrical discharge machining through powder metallurgy process

    OpenAIRE

    C. Mathalai Sundaram; Sivasubramanian, R.; Sivakumar, M.

    2014-01-01

    Electrical discharge machining (EDM) is one of the widely used nontraditional machining methods to produce die cavities by the erosive effect of electrical discharges. This method is popular due to the fact that a relatively soft electrically conductive tool electrode can machine hard work piece. Copper electrode is normally used for machining process. Electrode wear rate is the major drawback for EDM researchers. This research focus on fabrication of metal matrix composite (MMC) electrode by...

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

    OpenAIRE

    Pop, A.(National Institute for Physics and Nuclear Engineering, Bucharest, Romania); Manea, F.; Orha, C.; Motoc, S.; Llinoiu, E.; Vaszilcsin, N.; Schoonman, J.

    2012-01-01

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

  13. Polyaniline/polysulfone composite film electrode for simultaneous determination of hydroquinone and catechol

    International Nuclear Information System (INIS)

    Highlights: ► We prepared a composite film which has bi-layers with asymmetric microstructure and relatively rich porosity which provides larger surface area for electrochemical reaction. ► The outer polysulfone layer is propitious for the organic molecules to enrich on the composite film, which brings great enhancement in electron transfer kinetics. ► The composite film electrode can be used to detect qualitatively or quantitatively hydroquinone and catechol in the single solute or mixed systems. - Abstract: Polyaniline (PAN)/polysulfone (PSF) composite film electrodes were successfully prepared by electropolymerization using cyclic votammetry technique. The composite film electrodes show a great enhancement in electron transfer kinetics, and the separation between oxidation and reduction peaks (ΔEp) decreases from 200 to 35 mV for hydroquinone (H2Q) and from 275 to 42 mV for catechol (CC) at bare Pt and composite film electrodes respectively. In their mixed systems, the redox peak of H2Q and two pairs of redox peaks of CC on this composite film electrode could be obviously distinguished which indicates the composite film electrodes have excellent electrocatalytic activity and reversibility towards the oxidation of two diphenols (hydroquinone and catechol). The linear relationships between the peak current and concentration are observed for single solute and mixed systems within the certain concentration range, implying that the composite film electrodes have potential application in the qualitative or quantitative analysis of diphenol.

  14. Synthesis and characterization of tin oxide/carbon aerogel composite electrodes for electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Sung-Woo; Hyun, Sang-Hoon [School of Advanced Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749 (Korea)

    2007-10-11

    Two types of carbon aerogel-based functional electrodes for supercapacitor applications are developed. To improve the electrochemical performance of the electrodes, carbon aerogels are doped with pseudocapacitive tin oxide either by impregnating tin oxide sol into resorcinol-formaldehyde (RF) wet gels (Method I), or by impregnating tin tetrachloride solution into carbon aerogel electrodes (Method II). The electrodes are heat-treated to 450 C in air to activate the electrode surface and complete the oxidation of tin-precursors in the network structure of the aerogel. The effects of different impregnation methods on the physical/electrochemical properties of the composite electrodes are investigated. Microstructural and compositional variations of the electrodes with tin oxide doping are also examined by scanning electron microscopy and energy dispersive X-ray analysis. The tin oxide/carbon aerogel composite electrodes synthesized by both methods have similar specific capacitances (66-70 F g{sup -1}). Composite electrodes synthesized via Method II showed better cyclic stability compared with electrodes synthesized via Method I. (author)

  15. Kinetics of CO/CO2 and H2/H2O reactions at Ni-based and ceria-based solid-oxide-cell electrodes

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2015-01-01

    , a composite of nickel and yttria/scandia stabilized zirconia (Ni–SZ). Ni–SZ is known to be more active for H2/H2O than for CO/CO2 reactions, but the reported relative activity varies widely. Here we compare AC impedance and DC current–overpotential data measured in the two gas environments for several...... the electrochemical reactions CO2 + 2e 4 CO + O2 and H2O + 2e 4 H2 + O2, for which the electrocatalytic activities of different electrodes differ considerably. The relative activities in CO/CO2 and H2/H2O and the nature of the differences are not well studied, even for the most common fuel-electrode material...... and porous Ni–SZ electrodes, the ratio of electrode polarization resistance in CO/CO2 vs. H2/H2O decreases from 33 to 2. Experiments and modelling suggest that the ratio decreases due to a lower concentration of impurities blocking the three phase boundary and due to the nature of the reaction zone extension...

  16. Development of new metal matrix composite electrodes for electrical discharge machining through powder metallurgy process

    Directory of Open Access Journals (Sweden)

    C. Mathalai Sundaram

    2014-12-01

    Full Text Available Electrical discharge machining (EDM is one of the widely used nontraditional machining methods to produce die cavities by the erosive effect of electrical discharges. This method is popular due to the fact that a relatively soft electrically conductive tool electrode can machine hard work piece. Copper electrode is normally used for machining process. Electrode wear rate is the major drawback for EDM researchers. This research focus on fabrication of metal matrix composite (MMC electrode by mixing copper powder with titanium carbide (TiC and Tungsten carbide (WC powder through powder metallurgy process, Copper powder is the major amount of mixing proportion with TiC and WC. However, this paper focus on the early stage of the project where powder metallurgy route was used to determine suitable mixing time, compaction pressure and sintering and compacting process in producing EDM electrode. The newly prepared composite electrodes in different composition are tested in EDM for OHNS steel.

  17. Compressed multiwall carbon nanotube composite electrodes provide enhanced electroanalytical performance for determination of serotonin

    International Nuclear Information System (INIS)

    Serotonin (5-HT) is an important neurochemical that is present in high concentrations within the intestinal tract. Carbon fibre and boron-doped diamond based electrodes have been widely used to date for monitoring 5-HT, however these electrodes are prone to fouling and are difficult to fabricate in certain sizes and geometries. Carbon nanotubes have shown potential as a suitable material for electroanalytical monitoring of 5-HT but can be difficult to manipulate into a suitable form. The fabrication of composite electrodes is an approach that can shape conductive materials into practical electrode geometries suitable for biological environments. This work investigated how compression of multiwall carbon nanotubes (MWCNTs) epoxy composite electrodes can influence their electroanalytical performance. Highly compressed composite electrodes displayed significant improvements in their electrochemical properties along with decreased internal and charge transfer resistance, reproducible behaviour and improved batch to batch variability when compared to non-compressed composite electrodes. Compression of MWCNT epoxy composite electrodes resulted in an increased current response for potassium ferricyanide, ruthenium hexaammine and dopamine, by preferentially removing the epoxy during compression and increasing the electrochemical active surface of the final electrode. For the detection of serotonin, compressed electrodes have a lower limit of detection and improved sensitivity compared to non-compressed electrodes. Fouling studies were carried out in 10 μM serotonin where the MWCNT compressed electrodes were shown to be less prone to fouling than non-compressed electrodes. This work indicates that the compression of MWCNT carbon-epoxy can result in a highly conductive material that can be moulded to various geometries, thus providing scope for electroanalytical measurements and the production of a wide range of analytical devices for a variety of systems

  18. Novel architecture of composite electrode for optimization of lithium battery performance

    OpenAIRE

    Guy, D.; LESTRIEZ, B; Bouchet, R.; Gaudefroy, Vincent; Guyomard, D.

    2006-01-01

    We show that the polymeric binder of the composite electrode may have an important role on the lithium trivanadate Li1.2V3O8 electrode performance. We describe a new tailored polymeric binder combination with controlled polymerfiller (carbon black) interactions that allows the preparation of new and more efficient electrode architecture. Using this polymeric binder, composite electrodes based on Li1.2V3O8 display a room temperature cycling capacity of 280 mAh g−1 (C/5 rate, 3.32 V) i...

  19. Graphite-graphite oxide composite electrode for vanadium redox flow battery

    International Nuclear Information System (INIS)

    Highlights: → A new composite electrode is designed for vanadium redox flow battery (VRB). → The graphite oxide (GO) is used as electrode reactions catalyst. → The excellent electrode activity is attributed to the oxygen-containing groups attached on the GO surface. → A catalytic mechanism of the GO towards the redox reactions is presumed. - Abstract: A graphite/graphite oxide (GO) composite electrode for vanadium redox battery (VRB) was prepared successfully in this paper. The materials were characterized with X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The specific surface area was measured by the Brunauer-Emmett-Teller method. The redox reactions of [VO2]+/[VO]2+ and V3+/V2+ were studied with cyclic voltammetry and electrochemical impedance spectroscopy. The results indicated that the electrochemical performances of the electrode were improved greatly when 3 wt% GO was added into graphite electrode. The redox peak currents of [VO2]+/[VO]2+ and V3+/V2+ couples on the composite electrode were increased nearly twice as large as that on the graphite electrode, and the charge transfer resistances of the redox pairs on the composite electrode are also reduced. The enhanced electrochemical activity could be ascribed to the presence of plentiful oxygen functional groups on the basal planes and sheet edges of the GO and large specific surface areas introduced by the GO.

  20. Ceria and strontium titanate based electrodes

    DEFF Research Database (Denmark)

    2010-01-01

    A ceramic anode structure obtainable by a process comprising the steps of: (a) providing a slurry by dispersing a powder of an electronically conductive phase and by adding a binder to the dispersion, in which said powder is selected from the group consisting of niobium-doped strontium titanate, ...

  1. Aqueous processing of composite lithium ion electrode material

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Investigations of rate limitation in nanostructured composite electrodes and experiments towards a 3D Li-ion microbattery

    OpenAIRE

    Johns, Phillip A.

    2011-01-01

    The factors effecting discharge rate limitation within LiFePO4 composite electrode structures have been investigated. It was found that for composite electrodes containing ‘small particles’ of active material solid state processes are not necessarily rate limiting. A simple model has been developed to describe the rate limitation that occurs in the composite electrode structure due to electrolyte concentration, electrode thickness and lithium ion transference number. The conformal electrodepo...

  3. Sulfur tolerant composite cermet electrodes for solid oxide electrochemical cells

    Science.gov (United States)

    Isenberg, Arnold O.

    1987-01-01

    An electrochemical apparatus is made containing an exterior electrode bonded to the exterior of a tubular, solid, oxygen ion conducting electrolyte where the electrolyte is also in contact with an interior electrode, said exterior electrode comprising particles of an electronic conductor contacting the electrolyte, where a ceramic metal oxide coating partially surrounds the particles and is bonded to the electrolyte, and where a coating of an ionic-electronic conductive material is attached to the ceramic metal oxide coating and to the exposed portions of the particles.

  4. Carbon nanotube/Co3O4 composite for air electrode of lithium-air battery

    OpenAIRE

    Yoon, Taek Han; Park, Yong Joon

    2012-01-01

    A carbon nanotube [CNT]/Co3O4 composite is introduced as a catalyst for the air electrode of lithium-air [Li/air] batteries. Co3O4 nanoparticles are successfully attached to the sidewall of the CNT by a hydrothermal method. A high discharge capacity and a low overvoltage indicate that the CNT/Co3O4 composite is a very promising catalyst for the air electrode of Li/air batteries.

  5. Graphite–castor oil polyurethane composite electrode surfaces – AFM morphological and electrochemical characterisation

    OpenAIRE

    Chiorcea-Paquim, Ana-Maria; Diculescu, Victor Constantin; Cervini, Priscila; Cavalheiro, Eder Tadeu Gomes; Brett, Ana Maria Oliveira

    2014-01-01

    Graphite–castor oil polyurethane composite electrodes with different graphite weight percentages, 30–70% graphite–polyurethane w w−1, were morphologically studied by atomic force microscopy (AFM) and voltammetry. AFM images and r.m.s. roughness measurements demonstrated that the polyurethane roughness decreased with increasing the graphite content, composites of 50% and 60% graphite–polyurethane w w−1 showing the smother electrode surface. The electrochemical characterisation was performed in...

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

    OpenAIRE

    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 ...

  7. Sustainable selective oxidations using ceria-based materials

    NARCIS (Netherlands)

    J. Beckers; G. Rothenberg

    2010-01-01

    This Perspective covers sustainable oxidation processes using doped cerias, ceria-supported catalysts and ceria-based mixed oxides. Firstly, we consider the general properties of ceria-based catalysts. We outline the advantages of the ceria redox cycle, and explain the dynamic behaviour of these cat

  8. Research Progress of Graphene and Its Composites as Electrodes for Capacitive Deionization

    Directory of Open Access Journals (Sweden)

    FENG Ai-Hu, YU Yun, SONG Li-Xin

    2016-02-01

    Full Text Available Capacitive deionization is an energy-efficient and environment-friendly desalination method, which forces ionic species toward oppositely charged high-surface-area electrodes under an electric field to achieve the purpose of desalination. The key technology is to prepare electrode materials, which require high specific surface area, reasonable pore size distribution and excellent electrical conductivity. Graphene is a desired kind of electrode material used in capacitive deionization for its high specific surface area and wonderful conductivity. However, the actual specific surface area is far below the theoretical value due to the effect of aggregation of graphene. The three-dimensional graphene or the composite materials can overcome aggregation effect to improve the performance of electrode. The research progress of the capacitive deionization technology based on graphene and its composite electrode are reviewed in detail. The existing problems and application prospect are also objectively pointed out in this review.

  9. Influence of ceria on the thermally durability of Pt/Rh automotive catalyst

    International Nuclear Information System (INIS)

    Full text: The use of cerium oxide as an oxygen storage component in automotive three-way catalysts has been well established. More recently the requirement of the three-way catalysts against the increase of the severity in emission standards has focused attention on the development of more active, durable catalysts. The thermally durability of Pt/Rh catalyst can be achieved by the utilization of thermally stable ceria as well as optimization of washcoat composition and structure in order to control the extent of interaction between PGM and ceria. In the present paper, we describe the influence of newly developed washcoat components and PGM interaction with ceria on catalytic performance. First, to clear that the interaction between PGM and ceria contributes to catalytic performance, several kinds of catalysts which have the varied interactions between PGM and ceria were prepared using engineered washcoat techniques and evaluated in the model gas reactor. It was obvious that the difference in performance among them after aging derived from a diversity of interactions between Pt, Rh, and ceria. Second, for the purpose of determining the thermally durability of the developed Pt/Rh catalyst, the catalysts including the current catalyst were aged under three different temperatures and evaluated on engine dynamometer. Result of engine dynamometer evaluation revealed that significant improvement in the thermal durability can be achieved by optimizing the PGM-ceria interaction. In conclusion, we recognize that a thermal durability of a three-way catalyst can be improved by the stabilization of proper PGM-ceria interaction after aging as well as the utilization of thermally durable ceria material

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

    Energy Technology Data Exchange (ETDEWEB)

    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).

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  15. Investigation on Mg and Sc co-doped Ceria electrolyte for IT-SOFC

    Directory of Open Access Journals (Sweden)

    P.Ravi Chandran

    2014-07-01

    Full Text Available Nanocrystalline form of pure ceria (CeO2 and metal (Mg or Sc doped ceria was attempted for 10 mol %. Also, Mg and Sc co-doped ceria with Ce1-x(Mg0.5Sc0.5xO2 (x=0-0.24 was prepared as an electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs by co-precipitation method. The synthesized different compositions of pure and doped nanocrystalline powders were then subjected to powder X-ray diffraction (XRD for phase and structural identification. All the nanocrystalline samples were found to be ceria based solid solutions of fluorite type structures. A.C. impedance spectroscopy measurements in the frequency range of 50Hz to 5MHz was carried out to study the grain, grain boundary and ionic conductivity of doped ceria samples in the temperature range of 400-600oC. The sample Ce0.84(Mg0.5Sc0.50.16O2 composition showed highest ionic conductivity i.e., 1.923 x 10-2 S/cm at 500oC. Its morphology and composition was investigated using scanning electron microscopic analysis (SEM and energy dispersive X-ray spectrometry (EDS and conductivity behavior was compared with those of pure ceria and singly doped ceria electrolytes namely Ce0.9Mg0.1O2 and Ce0.9Sc0.1O2. The impedance analysis reveals that the sample Ce0.9Mg0.1O2 was found to have higher ionic conductivity compared to Ce0.9Sc0.1O2 in the temperature range of 400–600°C. The co-doped ceria showed a much higher conductivity in air at 500oC in comparison to that of singly doped ceria. Therefore, these co-doped ceria are also the more ideal electrolyte materials for IT-SOFCs. Nyquist plot shows the major contributions were due to the grain boundary resistance contributions which accounts for the higher ionic conductivity in case of the dopants. These dopant effect on the ceria is discussed in detail.

  16. Kinetic Studies on Ni-YSZ Composite Electrodes

    DEFF Research Database (Denmark)

    Njodzefon, Jean-Claude; Hjelm, Johan; Graves, Christopher R.; Sudireddy, Bhaskar Reddy

    Introduction Polarization of the Solid Oxide Cell (SOC) causes current to flow. If the fuel electrode is anodically polarized, the cell operates in fuel cell mode, oxidizing a fuel like hydrogen, carbon monoxide or hydrocarbons. In cathodic polarization the cell operates in electrolysis mode, red...

  17. Honeycomb-structured porous poly(3,4-ethylenedioxythiophene) composite layers on a gold electrode

    International Nuclear Information System (INIS)

    Three microstructured electrodes modified with poly(3,4-ethylenedioxythiophene) (PEDOT) were obtained. One electrode was modified with PEDOT doped with poly(4-lithium styrenesulfonic acid) (PSSLi), the second one with a PEDOT + polyacrylic acid composite doped with PSSLi, and the third one with a PEDOT + anthranilic acid composite doped with poly(4-styrenesulfonic acid). The three electrodes were prepared using templates of polystyrene latex spheres (PS). The templates were deposited on the electrode using our dip-coating-like technique that we developed by optimizing key parameters, such as PS and sodium dodecyl sulfate concentration, angle of inclination, and decantation rate. The structure of the templates was verified by optical microscopy. A conducting polymer layer was obtained by electropolymerization from appropriate monomer solutions. In the final stage, the template was dissolved in toluene and the morphology of the resulting honeycomb-structure was examined by atomic force microscopy and scanning electron microscopy methods. The electrochemical properties of the electrodes were tested by cyclic voltammetry and electrochemical impedance spectroscopy. - Highlights: • We developed microstructured electrodes based on conducting composites. • We obtained three composites with PEDOT, polyacrylic acid and anthranilic acid. • All structures were obtained on a polystyrene template via electropolymerization. • SDS surfactant plays a key role during template deposition process

  18. Honeycomb-structured porous poly(3,4-ethylenedioxythiophene) composite layers on a gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Krzyczmonik, Paweł, E-mail: pawel@chemia.uni.lodz.pl [Department of Inorganic and Analytical Chemistry, Team of Electroanalysis and Electrochemistry, University of Lodz, Tamka 12, 91-403 Lodz (Poland); Socha, Ewelina; Skrzypek, Sławomira [Department of Inorganic and Analytical Chemistry, Team of Electroanalysis and Electrochemistry, University of Lodz, Tamka 12, 91-403 Lodz (Poland); Soliwoda, Katarzyna; Celichowski, Grzegorz; Grobelny, Jarosław [Department of Materials Technology and Chemistry, University of Lodz, Pomorska 163, 90-236 Lodz (Poland)

    2014-08-28

    Three microstructured electrodes modified with poly(3,4-ethylenedioxythiophene) (PEDOT) were obtained. One electrode was modified with PEDOT doped with poly(4-lithium styrenesulfonic acid) (PSSLi), the second one with a PEDOT + polyacrylic acid composite doped with PSSLi, and the third one with a PEDOT + anthranilic acid composite doped with poly(4-styrenesulfonic acid). The three electrodes were prepared using templates of polystyrene latex spheres (PS). The templates were deposited on the electrode using our dip-coating-like technique that we developed by optimizing key parameters, such as PS and sodium dodecyl sulfate concentration, angle of inclination, and decantation rate. The structure of the templates was verified by optical microscopy. A conducting polymer layer was obtained by electropolymerization from appropriate monomer solutions. In the final stage, the template was dissolved in toluene and the morphology of the resulting honeycomb-structure was examined by atomic force microscopy and scanning electron microscopy methods. The electrochemical properties of the electrodes were tested by cyclic voltammetry and electrochemical impedance spectroscopy. - Highlights: • We developed microstructured electrodes based on conducting composites. • We obtained three composites with PEDOT, polyacrylic acid and anthranilic acid. • All structures were obtained on a polystyrene template via electropolymerization. • SDS surfactant plays a key role during template deposition process.

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

    Science.gov (United States)

    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

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

    NARCIS (Netherlands)

    Pop, A.; Manea, F.; Orha, C.; Motoc, S.; Llinoiu, E.; Vaszilcsin, N.; Schoonman, J.

    2012-01-01

    The aim of this study was to prepare three types of multiwall carbon nanotubes (CNT)-based composite electrodes and to modify their surface by copper electrodeposition for nonenzymatic oxidation and determination of glucose from aqueous solution. Copper-decorated multiwall carbon nanotubes composite

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

    Science.gov (United States)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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

  4. Preparation of highly porous NiO–gadolinium-doped ceria nano-composite powders by one-pot glycine nitrate process for anode-supported tubular solid oxide fuel cells

    Directory of Open Access Journals (Sweden)

    Seung-Young Park

    2014-12-01

    Full Text Available Highly porous NiO–gadolinium-doped ceria (GDC nano-composite powders are synthesized by a one-pot glycine nitrate process and applied to the fabrication of Ni–YSZ (yttria-stabilized zirconia-supported tubular solid oxide fuel cells (SOFCs with a cell configuration of Ni–YSZ/Ni/Ni–GDC/GDC/LSCF (La0.6Sr0.4Co0.2Fe0.8O3−δ–GDC/LSCF. The power density of the cell is as high as 413 mW cm−2 at 600 °C, which is 1.37 times higher than that of an identically configured cell fabricated using ball milling-derived NiO–GDC powders (301 mW cm−2. The high porosity of the powders and the good mixing between the NiO and GDC primary nanoparticles due to the abrupt combustion of the precursors effectively suppress the densification, coarsening, and agglomeration of NiO and GDC particles during sintering, resulting in a highly porous Ni–GDC anode layer with good dispersion of Ni and GDC particles and a cell with significantly enhanced power density.

  5. A Graphite-Polyurethane Composite Electrode for the Analysis of Furosemide

    OpenAIRE

    Semaan, Felipe S.; Pinto, Edilson M.; Cavalheiro, Éder T. G.; Brett, Christopher M. A.

    2008-01-01

    A graphite-polyurethane composite electrode has been used for the determination of furosemide, a antihypertensive drug, in pharmaceutical samples by anodic oxidation. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the electrooxidation process at +1.0 V vs. SCE over a wide pH range, with the result that no adsorption of analyte or products occurs, unlike at other carbon-based electrode materials. Quantification was carried out using cyclic voltammetry, ...

  6. Composite electrode of carbon nanotubes and vitreous carbon for electron field emission

    OpenAIRE

    Matsubara, EY; Rosolen, JM; Silva, SRP

    2008-01-01

    In this work, the electron field emission behaviour of electrodes formed by carbon nanotubes (CNTs) grown onto monolithic vitreous carbon (VCarbon) substrates with microcavities is presented. Scanning electron microscopy was used to characterize the microstructure of the films. Tungsten probes, stainless steel sphere, and phosphor electrodes were employed in the electron field emission study. The CNT/VCarbon composite represents a route to inexpensive excellent large area electron emission ca...

  7. Catalysis by ceria and related materials

    CERN Document Server

    Trovarelli, Alessandro

    2013-01-01

    This book follows the 2002 edition of Catalysis by Ceria and Related Materials, which was the first book entirely devoted to ceria and its catalytic properties. In the ten years since the first edition a massive amount of work has been carried out in the field, and ceria has gained a prominent position in catalysis as one of the most valuable material for several applications. This second edition covers fundamental and applied aspects of the latest advances in ceria-based materials with a special focus on structural, redox and catalytic features. Special emphasis is given to nano-engineered an

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

    Science.gov (United States)

    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.

  9. Modifying ceria (111) with a TiO2 nanocluster for enhanced reactivity.

    Science.gov (United States)

    Nolan, Michael

    2013-11-14

    Modification of ceria catalysts is of great interest for oxidation reactions such as oxidative dehydrogenation of alcohols. Improving the reactivity of ceria based catalysts for these reactions means that they can be run at lower temperatures and density functional theory (DFT) simulations of new structures and compositions are proving valuable in the development of these catalysts. In this paper, we have used DFT+U (DFT corrected for on-site Coulomb interactions) to examine the reactivity of a novel modification of ceria, namely, modifying with TiO2, using the example of a Ti2O4 species adsorbed on the ceria (111) surface. The oxygen vacancy formation energy in the Ti2O4-CeO2 system is significantly reduced over the bare ceria surfaces, which together with previous work on ceria-titania indicates that the presence of the interface favours oxygen vacancy formation. The energy gain upon hydrogenation of the catalyst, which is the rate determining step in oxidative dehydrogenation, further points to the improved oxidation power of this catalyst structure. PMID:24320294

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

    Science.gov (United States)

    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. PMID:26147828

  11. Effect of E8010-P1 electrode composition on the weld metal properties

    International Nuclear Information System (INIS)

    Different manufactures produce E8010-P1 electrode with different chemical compositions due to the relatively wide range of permissible alloying elements in the composition of this electrode. Four groups of E8010-P1 electrodes, with different compositions, were selected and effect of electrode composition on the microstructure and mechanical properties of weld meal were examined. Microstructural studies revealed that presence of the Mn, Mo and Ni in the weld metal influences significantly on the morphology of ferrite in the weld metal zone. Large amount of Mn (around 1%) in the weld metal leads to the formation of fine acicular ferrite in the weld metal. Furthermore, presence of Mo (around 0.4%) in the weld metal prevents formation of continuous grain boundary ferrite in the weld zone. Mechanical properties investigations reveal that the more acicular ferrite in the weld metal, the higher strength and ductility of this zone. -- Highlights: • Mn and Mo resulted in formation of acicular ferrite in the weld metal. • Composition of E8010-P1 has significant effect on the structural and mechanical properties of weld area. • Optimal chemical composition of pipe line E8010-P1 was determined

  12. Three-dimensional crisscross porous manganese oxide/carbon composite networks for high performance supercapacitor electrodes

    International Nuclear Information System (INIS)

    Highlights: • Three-dimensional inter-connected porous networks of manganese oxide/carbon composites were successfully developed. • The powdery composite possesses good conductivity and favorable porosity. • The composite electrode delivers an outstanding specific capacitance of 807 F g−1 at 1 A g−1. - Abstract: Manganese oxide/carbon (MnOx/C) composites have been successfully prepared via a high temperature heat treatment method followed by the electrochemical oxidation. The presence of carbon not only enhances the electronic conductivity of manganese oxides (MnOx), but also provides more active sites for the transformation of manganese monoxide (MnO) during the galvanostatic charge–discharge process. Simultaneity, the interconnected porous structures of MnOx/C samples are believed to provide a continuous channel for the diffusion of electrolyte ion and shorten the diffusion length of ions involved in the charge/discharge cycling processes. Consequently, these advantages endow the MnOx/C electrode a better capacitance performance, a superior long-term cyclic stability and outstanding rate capability compared with pristine MnOx. More importantly, the composites show a fascinating capacitance of 807 F g−1 at 1 A g−1, which is much higher than the reported hydrous RuO2 electrodes. It can be easily speculated that MnOx/C composites will act as a promising electrode materials for designing high-performance supercapacitors

  13. Fermi Potential across Working Solid Oxide Cells with Zirconia or Ceria Electrolytes

    DEFF Research Database (Denmark)

    Jacobsen, Torben; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2014-01-01

    A solid electrolyte will always possess a finite electronic conductivity, in particular electrolytes like doped ceria that easily get reduced and become mixed ionic and electronic conductors. This given rise too high leak currents through the solid oxide cell (SOC). Especially, problems have been...... observed for ceria based electrolytes, but also in case of solid oxide electrolyser cells (SOEC) with yttria stabilized zirconia (YSZ) big electronic leak currents have been observed for very high overvoltages on one or both electrodes. Furthermore, it is important to realize that the potential gradient...... various temperatures and operation conditions. Furthermore, the situation within cells based on gadolinia doped ceria (CGO) and on YSZ electrolytes are compared. Finally, it is discussed how the Fermi potential and electron conductivity will be affected by the various parameters including operation...

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

    Science.gov (United States)

    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

  15. Preparation and electrocatalytic property of Au-Pt/SnO2/GC composite electrode

    Institute of Scientific and Technical Information of China (English)

    YU Zhihui; XIE Jia; BAI Jie; TIAN Mi; XIA Dingguo

    2009-01-01

    Au-Pt/SnO2/GC composite electrode was prepared by self-assembling Au-Pt nanoparticles on SnO2 film, which was deposited on actived glassy carbon (GC). Atomic force microscopy (AFM) and scanning electron microscopy (SEM) images revealed that dense and uniform Au-Pt particles with 25-nm diameter were dispersed on SnO2 film. X-ray photoelectron spectroscopy (XPS) results proved that there was an interaction between Au-Pt nanoparticles and SnO2 support. Electrochemical experiments showed that Au-Pt/SnO2/GC composite electrode had a good electrocatalytic activity to the oxidation of methanol.

  16. Application of spherical Ni(OH)2/CNTs composite electrode in asymmetric supercapacitor

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-feng; RUAN Dian-bo; YOU Zheng

    2006-01-01

    The composite electrodes consisting of carbon nanotubes and spherical Ni(OH)2 are developed by mixing nickel hydroxide, carbon nanotubes and carbonyl nickel powder together in 8-1-1 ratio. A maximum capacitance of 311 F/g is obtained for an electrode prepared with the precipitation process. In order to enhance energy density, an asymmetric type pseudo-capacitor/electric double layer capacitor is considered and its electrochemical properties are investigated. Values for the specific energy and maximum specific power of 25.8 W-h/kg and 2.8 kW/kg, respectively, are demonstrated for a cell voltage between 0 and 1.6 V. By using the modified cathode of a Ni(OH)2/carbon nanotube composite electrode, the asymmetric supercapacitor exhibits high energy density and stable power characteristics.

  17. Nickel/carbon nanofibers composite electrodes as supercapacitors prepared by electrospinning

    International Nuclear Information System (INIS)

    Nickel-embedded carbon nanofibers were prepared by the processes of stabilization and carbonation after electrospinning a mixture solution of nickel acetate and polyacrylonitrile in N,N-dimethylformamide. The surface morphology and structure of composites were examined by scanning electron microscope (SEM) and X-ray diffraction (XRD). Compared with performances of composite electrodes with different mass ratios of nickel and carbon by cyclic voltammetry (CV) and chronopotentiogram test, the results show that the introduction of a proper proportion of nickel into carbon could enhance both specific capacitance (SC) and electrochemical stability. The specific capacitance of the carbon nanofiber electrode without the Ni loading was 50 F/g, while that of 22.4 wt.% Ni/carbon electrode increased to 164 F/g. The improved specific capacitance may be attributed to synergic effects from each pristine component, and the electrochemical catalysis effect of nickel.

  18. Electrocatalytic oxidation of phenol using Ni-Al2O3 composite-coating electrodes

    International Nuclear Information System (INIS)

    Electrocatalytic oxidation of phenol on Ni-Al2O3 composite electrodes was investigated in wastewater. Firstly Ni-Al2O3 composite-coating electrodes was prepared by electrodeposition of Ni-Al2O3 composite on the mild steel substrates from the citrate bath containing NiSO4 as a source of nickel and alumina particles. The electrodeposited composite coating was heat treated at 400 deg. C and characterized by using different techniques such as scanning electron microscope (SEM), electron dispersive X-ray analysis (EDX), and X-ray diffraction (XRD). On using this composite coating as electrodes it was found that the highest electrocatalytic activity was achieved in presence of [H2SO4 (2 g/l) + FeSO4 (20 mg/l)]. In presence of each of NaOH and H2SO4 the activity of the electrode was poor. The electro-Fenton's reagent was the most suitable oxidizing agent for the oxidation of phenol. The reaction between hydrogen peroxide, produced at a cathode, with ferrous sulphate produces hydroxyl radical, one of the strongest inorganic oxidants. In the presence of organic compound, the hydroxyl radical oxidizes the degradable compound to a free radicals and water. Further chain oxidation of the organic radicals leads to a total decomposition of the organic compound, leaving only carbon dioxide and water. Optimizing the conditions that ensure effective electrochemical degradation of phenol on Ni-Al2O3 composite-coating electrodes necessitates the control of all the operating factors.

  19. Computer Simulations of Composite Electrodes in Solid-Oxide Fuel-Cells

    Energy Technology Data Exchange (ETDEWEB)

    Sunde, Svein

    1999-07-01

    Fuel cells are devices for converting the combined chemical (free) energy of fuels and oxygen (air) directly to electrical energy without relying on the dynamic action of steam heated by reacting fuel-oxygen mixtures, like in steam turbines, or of the reacting gas mixtures themselves, like in gas turbines. The basic rationale for fuel cells is their high efficiencies as compared to indirect-conversion methods. Fuel cells are currently being considered for a number of applications, among them de-centralised power supply. Fuel cells come in five basic types and are usually classified according to the type of electrolyte used, which in turn to a significant degree limits the options for anode and cathode materials. The solid-oxide fuel-cell (SOFC) , with which this thesis is concerned, is thus named after its oxide electrolyte, typically the oxide-ion conducting material yttria-stabilised zirconia (YSZ). While the cathode of an SOFC is often uniform in chemical composition (or at least intended to be), various problems of delamination, cracking etc. associated with the use of metallic anode electrocatalysts led to the development of composite SOFC anodes. Porous anodes consisting of Ni and YSZ particles in roughly 50/50 wt-% mixtures are now almost standard with any SOFC-development programme. The designer of composite SOFC electrodes is faced with at least three, interrelated questions: (1) What will be the optimum microstructure and composition of the composite electrode? (2) If the structure changes during operation, as is often observed, what will be the consequences for the internal losses in the cell? (3) How do we interpret electrochemical and conductivity measurements with regard to structure and composition? It is the primary purpose of this thesis to provide a framework for modelling the electrochemical and transport properties of composite electrodes for SOFC, and to arrive at some new insights that cannot be offered by experiment alone. Emphasis is put on

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  1. Fabrication of W–Cu/CeO2 composites with excellent electric conductivity and high strength prepared from copper-coated tungsten and Ceria powders

    International Nuclear Information System (INIS)

    W–Cu/CeO2 composites with excellent electric conductivity and high strength have been prepared from Cu-coated W and CeO2 composite powders. The phase and morphology of W–Cu/CeO2 composite powders and W–Cu/CeO2 composites are characterized by x-ray diffraction, field-emission scanning electron microscopy and energy-dispersive spectroscopy. The relative density, microhardness, electrical conductivity, and bending strength of the sintered samples are also examined. Results show that the addition of Cu-coated CeO2 composite powders significantly affect the microstructure and properties of W–Cu composite materials. The low content of CeO2 (0, 0.25 wt%, 0.5 wt%) have made an inconspicuous impression on bending strength and microhardness. While the composites still exhibit a best bending strength of 1102.7 MPa, which is higher than the national standard (W–Cu) of 39.28%. When the addition of CeO2 reached 0.25 wt%, the composites show the best electric conductivity of 69.41% IACS, which is higher than the national standard (W–Cu) of 65.26%. However, with further addition of CeO2 to 1 wt% and 2 wt%, the composites show numerous pores and aggregated particles, which is prone to damage the properties of the alloys

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

    Science.gov (United States)

    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. PMID:26714293

  3. Electrophoretic nanotechnology of composite electrodes for electrochemical supercapacitors.

    Science.gov (United States)

    Su, Y; Zhitomirsky, I

    2013-02-14

    The electrophoretic deposition (EPD) method has been developed for the fabrication of MnO(2)-multiwalled carbon nanotube (MWCNT) films for application in electrochemical supercapacitors (ESs). For MWCNT applications, which depend on electrical conductivity, it is challenging to achieve dispersion and EPD of pristine MWCNT and avoid defects due to chemical treatment or functionalization. An important finding was the possibility of efficient dispersion and controlled EPD of MWCNT using calconcarboxylic acid (CCA). Moreover, the use of CCA allowed efficient dispersion of MnO(2) in concentrated suspensions and EPD of MnO(2) films. The comparison of the experimental data for chromotrope FB (CFB) and CCA and chemical structures of the molecules provided insight into the mechanism of CCA adsorption on MnO(2). The fabrication of stable suspensions of MnO(2) nanoparticles containing MWCNT, and controlled codeposition of both materials is a crucial aspect in the EPD of composites. The new approach was based on the use of CCA as a charging and dispersing agent for EPD of MnO(2) nanoparticles and MWCNT. The deposition yield measurements at various experimental conditions and Fourier transform infrared spectroscopy data, coupled with results of electron microscopy, thermogravimetric, and differential thermal analysis provided evidence of the formation of MnO(2)-MWCNT composites. The electrochemical testing results and impedance spectroscopy data showed good capacitive behavior of the composite films and the beneficial effect of MWCNTs. PMID:22662969

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

    Science.gov (United States)

    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. PMID:25950937

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

    Science.gov (United States)

    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

  6. Electrochemical detection and degradation of ibuprofen from water on multi-walled carbon nanotubes-epoxy composite electrode

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

    This work describes the electrochemical behaviour of ibuprofen on two types of multi-walled carbon nanotubes based composite electrodes,i.e.,multi-walled carbon nanotubes-epoxy (MWCNT) and silver-modified zeolite-multi-walled carbon nanotubes-epoxy (AgZMWCNT) composites electrodes.The composite electrodes were obtained using two-roll mill procedure.SEM images of surfaces of the composites revealed a homogeneous distribution of the composite components within the epoxy matrix.AgZMWCNT composite electrode exhibited the better electrical conductivity and larger electroactive surface area.The electrochemical determination of ibuprofen (IBP) was achieved using AgZMWCNT by cyclic voltammetry,differential-pulsed voltammetry,square-wave voltammetry and chronoamperometry.The IBP degradation occurred on both composite electrodes under controlled electrolysis at 1.2 and 1.75 V vs.Ag/AgCl,and IBP concentration was determined comparatively by differential-pulsed voltammetry,under optimized conditions using AgZMWCNT electrode and UV-Vis spectrophotometry methods to determine the IBP degradation performance for each electrode.AgZMWCNT electrode exhibited a dual character allowing a double application in IBP degradation process and its control.

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

    Science.gov (United States)

    Palmre, Viljar

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

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

    Science.gov (United States)

    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. Composite supercapacitor electrodes made of activated carbon/PEDOT:PSS and activated carbon/doped PEDOT

    Indian Academy of Sciences (India)

    T S Sonia; P A Mini; R Nandhini; Kalluri Sujith; Balakrishnan Avinash; S V Nair; K R V Subramanian

    2013-08-01

    In this paper, we report on the high electrical storage capacity of composite electrodes made from nanoscale activated carbon combined with either poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) or PEDOT doped with multiple dopants such as ammonium persulfate (APS) and dimethyl sulfoxide (DMSO). The composites were fabricated by electropolymerization of the conducting polymers (PEDOT:PSS, doped PEDOT) onto the nanoscale activated carbon backbone, wherein the nanoscale activated carbon was produced by ball-milling followed by chemical and thermal treatments. Activated carbon/PEDOT:PSS yielded capacitance values of 640 F g-1 and 26mF cm-2, while activated carbon/doped PEDOT yielded capacitances of 1183 F g-1 and 42 mF cm-2 at 10 mV s-1. This is more than five times the storage capacity previously reported for activated carbon–PEDOT composites. Further, use of multiple dopants in PEDOT improved the storage performance of the composite electrode well over that of PEDOT:PSS. The composite electrodes were characterized for their electrochemical behaviour, structural and morphological details and electronic conductivity and showed promise as high-performance energy storage systems.

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

    Science.gov (United States)

    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.

  11. Preparation and electrochemical characterization of C/PANI composite electrode materials

    Institute of Scientific and Technical Information of China (English)

    LAI Yan-qing; LI Jing; LI Jie; LU Hai; ZHANG Zhi-an; LIU Ye-xiang

    2006-01-01

    Taking the nano-sized carbon black and aniline monomer as precursor and (NH4)2 S2 O6 as oxidant, the well coated C/polyaniline(C/PANI) composite materials were prepared by in situ polymerization of the aniline on the surface of well-dispersed nano-sized carbon black for supercapacitor. The micro-structure of the C/PANI composite electrode materials were analyzed by SEM. The electrochemical properties of C/ PANI and PANI composite electrode were characterized by means of the galvanostatic charge-discharge experiment, cyclic voltammetric measurement and impedance spectroscopy analysis. The results show that by adding the nano-sized carbon black in the process of chemical polymerization of the aniline, the polyaniline can be in situ polymerized and well-coated onto the carbon black particles, which may effectively improve the aggregation of particles and the electrolyte penetration.with PANI electrode, C/PANI electrode shows more desired capacitance characteristics, smaller internal resistance and better cycle performance.

  12. Thermal plasma of electric arc discharge in air between composite Cu-C electrodes

    International Nuclear Information System (INIS)

    The complex technique of plasma property studies is suggested. As the first step the radial profiles of temperature and electron density in plasma of free burning electric arc discharge in air between Cu-C composite and brass electrodes, as well as copper electrodes in air flow, were measured by optical emission spectroscopy techniques. As the next step the radial profiles of electric conductivity of plasma mixture were calculated by solution of energy balance equation. The electron density is obtained from electric conductivity by calculation in assumption of local thermodynamical equilibrium in plasma.

  13. PEDOT-based composites as electrode materials for supercapacitors

    Science.gov (United States)

    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.

  14. Effect of samarium addition and annealing on the properties of electrodeposited ceria thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zivkovic, L. [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie, LECIME, CNRS UMR 7575, Chimie ParisTech (ENSCP)-Paris, 11 rue Pierre et Marie Curie, 75231 Paris cedex 05 (France); The Vinca Institute of Nuclear Sciences, University of Belgrade, 11 001 Belgrade, PO BOX 522 (Serbia); Lair, V., E-mail: virginie-lair@ens.chimie-paristech.f [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie, LECIME, CNRS UMR 7575, Chimie ParisTech (ENSCP)-Paris, 11 rue Pierre et Marie Curie, 75231 Paris cedex 05 (France); Lupan, O. [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie, LECIME, CNRS UMR 7575, Chimie ParisTech (ENSCP)-Paris, 11 rue Pierre et Marie Curie, 75231 Paris cedex 05 (France); Department of Microelectronics and Semiconductor Devices, Technical University of Moldova, 168 Stefan cel Mare Blvd., Chisinau, MD-2004 (Moldova, Republic of); Ringuede, A. [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie, LECIME, CNRS UMR 7575, Chimie ParisTech (ENSCP)-Paris, 11 rue Pierre et Marie Curie, 75231 Paris cedex 05 (France)

    2011-03-31

    Samarium (Sm)-doped ceria (CeO{sub 2}) (SDC) is a promising material for high temperature electrochemical devices. Our work demonstrates that thin SDC films can be prepared by a cost-effective electrodeposition method at a low-temperature (30 {sup o}C) and - 0.8 V/SCE (saturated calomel electrode) potential. Analysis of the structural properties of the obtained SDC films, as-grown and annealed at 600 {sup o}C, has been carried out by X-ray diffraction (XRD). Morphology and film composition were studied using scanning electronic microscopy and energy dispersive X-ray analysis. Vibrational properties were determined by Raman spectroscopy. The effects of samarium addition into the deposition bath on the final film composition have been studied. According to XRD results, film crystallographic properties are directly linked to the percentage of Sm incorporated in the CeO{sub 2} lattice. We report on the electrochemical deposition of the SDC films performed over a large range of Sm additions (0-30%). The effect of temperature annealing has been studied as well.

  15. The reduction and oxidation of ceria: A natural abundance triple oxygen isotope perspective

    Science.gov (United States)

    Hayles, Justin; Bao, Huiming

    2015-06-01

    Ceria (CeO2) is a heavily studied material in catalytic chemistry for use as an oxygen storage medium, oxygen partial pressure regulator, fuel additive, and for the production of syngas, among other applications. Ceria powders are readily reduced and lose structural oxygen when subjected to low pO2 and/or high temperature conditions. Such dis-stoichiometric ceria can then re-oxidize under higher pO2 and/or lower temperature by incorporating new oxygen into the previously formed oxygen site vacancies. Despite extensive studies on ceria, the mechanisms for oxygen adsorption-desorption, dissociation-association, and diffusion of oxygen species on ceria surface and within the crystal structure are not well known. We predict that a large kinetic oxygen isotope effect should accompany the release and incorporation of ceria oxygen. As the first attempt to determine the existence and the degree of the isotope effect, this study focuses on a set of simple room-temperature re-oxidation experiments that are also relevant to a laboratory procedure using ceria to measure the triple oxygen isotope composition of CO2. Triple-oxygen-isotope labeled ceria powders are heated at 700 °C and cooled under vacuum prior to exposure to air. By combining results from independent experimental sets with different initial oxygen isotope labels and using a combined mass-balance and triangulation approach, we have determined the isotope fractionation factors for both high temperature reduction in vacuum (⩽10-4 mbar) and room temperature re-oxidation in air. Results indicate that there is a 1.5‰ ± 0.8‰ increase in the δ18O value of ceria after being heated in vacuum at 700 °C for 1 h. When the vacuum is broken at room temperature, the previously heated ceria incorporates 3-19% of its final structural oxygen from air, with a δ18O value of 2.1-4.1+7.7 ‰ for the incorporated oxygen. The substantial incorporation of oxygen from air supports that oxygen mobility is high in vacancy

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

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jun; Zhitomirsky, Igor [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario (Canada); Yang, Quan Min [Inco Technical Services, Mississauga, Ontario (Canada)

    2008-12-01

    Manganese dioxide nanofibers with length ranged from 0.1 to 1 {mu}m 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{sup -2}, showed a capacitive behavior in the 0.1-0.5 M Na{sub 2}SO{sub 4} solutions. The highest specific capacitance (SC) of 155 F g{sup -1} was obtained at a scan rate of 2 mV s{sup -1} in the 0.5 M Na{sub 2}SO{sub 4} solutions. The SC increased with increasing MWCNT content in the composite materials and increasing Na{sub 2}SO{sub 4} concentration in the solutions and decreased with increasing scan rate. (author)

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

    Science.gov (United States)

    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.

  18. Strontium Titanate-based Composite Anodes for Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Kammer Hansen, Kent; Wallenberg, L.R.;

    2008-01-01

    Surfactant-assisted infiltration of Gd-doped ceria (CGO) in Nb-doped SrTiO3 (STN) was investigated as a potential fuel electrode for solid oxide fuel cells (SOFC). An electronically conductive backbone structure of STN was first fabricated at high temperatures and then combined with the mixed...... conducting and electrochemically active nano-sized CGO phase at low temperatures. Symmetrical cell measurements at open circuit voltage (OCV), showed that the electrochemical activity was maintained or even improved compared to Ni/YSZ fuel electrodes. The novel electrode had an electrode polarization...... resistance of 0.12 Omegacm2 and 0.44 Omegacm2 in humidified H2 at 850 ºC and 650 ºC, respectively. In addition, the ceramic composite electrode was shown to be redox stable. The electrode was actually activated with redox cycles at 650 ºC. The ceramic electrode structure thus presents a potential solution to...

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

    Science.gov (United States)

    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.

  20. Voltammetric detection of bisphenol a by a chitosan–graphene composite modified carbon ionic liquid electrode

    International Nuclear Information System (INIS)

    In this paper 1-ethyl-3-methylimidazolium tetrafluoroborate based carbon ionic liquid electrode (CILE) was fabricated and further modified with chitosan (CTS) and graphene (GR) composite film. The fabricated CTS-GR/CILE was further used for the investigation on the electrochemical behavior of bisphenol A (BPA) by cyclic voltammetry and differential pulse voltammetry. A well-defined anodic peak appeared at 0.436 V in 0.1 mol/L pH 8.0 Britton–Robinson buffer solution, which was attributed to the electrooxidation of BPA on the modified electrode. The electrochemical parameters of BPA on the modified electrode were calculated with the results of the charge transfer coefficient (α) as 0.662 and the apparent heterogeneous electron transfer rate constant (ks) as 1.36 s−1. Under the optimal conditions, a linear relationship between the oxidation peak current of BPA and its concentration can be obtained in the range from 0.1 μmol/L to 800.0 μmol/L with the limit of detection as 2.64 × 10−8 mol/L (3σ). The CTS-GR/CILE was applied to the detection of BPA content in plastic products with satisfactory results. - Highlights: ► A graphene modified carbon ionic liquid electrode was fabricated and characterized. ► Electrochemical behaviors of bisphenol A were investigated. ► Bisphenol A was detected by the proposed electrode.

  1. 2D Cross Sectional Analysis and Associated Electrochemistry of Composite Electrodes Containing Dispersed Agglomerates of Nanocrystalline Magnetite, Fe₃O₄.

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2014-01-01

    Full Text Available 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. Large-scale graphene-based composite films for flexible transparent electrodes fabricated by electrospray deposition

    Science.gov (United States)

    Kim, Woo Sik; Moon, Sook Young; Kim, Hui Jin; Park, Sungjin; Koyanagi, Jun; Huh, Hoon

    2014-12-01

    Large-scale transparent conducting electrodes were fabricated using the electrospray method on a glass wafer and polyethylene terephthalate film using chemically reduced graphene oxide and poly (3,4-ethylenedioxythiophene) (PEDOT). Graphene oxide (GO) is prepared by the modified Hummers method, and reduced GO (RG) is prepared at low temperature. By varying the concentration of RG and PEDOT of the composite material on the substrate, the electrical conductivity and transmittance of the electrode was controlled. The optical transmittance values of the graphene-based electrode at a wavelength of 550 nm were between 81 and 95% and had sheet resistances from 370 to 5400 Ω sq-1. After 1000 cycles of a bending test, the sheet resistances of the graphene-based composite films were unchanged. Different types of graphene and graphene-based electrodes were characterized by field-emission scanning electron microscopy, high-resolution transmission electron microscopy, high-resolution Raman spectroscopy, x-ray photoelectron spectroscopy, x-ray diffraction, transmittance, and electrical conductivity measurements.

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

    Science.gov (United States)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    Yamaguchi, Keisuke; Ueda, Takao; Nanasawa, Akira

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2015-01-01

    An electrochemical detection technique based on combination of was coulometric differential fast Fourier transformation admittance voltammetry (CDFFTAV) and nano-composite film modified glassy carbon electrode was successfully applied for sensitive determination of Amlodipine. The nano-composite film was made by a mixture of ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4), multiwall carbon nanotube and Au nanoparticles as electrochemical mediators. Studies reveal that the irreversible oxidation of Amlodipine was highly facile on the electrode surface. The electrochemical response was established on calculation of the charge under the admittance peak, which was obtained by discrete integration of the admittance response in a selected potential range, obtained in a flow injection analysis. Once established the best operative optimum conditions, the resulting nano-composite film electrode showed a catalytic effect on the oxidation of the analyte. The response is linear in the Amlodipine concentration range of 1.0 × 10(-9) to 2.0 × 10(-7)M with a detection limit of 1.25 × 10(-10)M. Moreover, the proposed technique exhibited high sensitivity, fast response time (less than 6s) and long-term stability and reproducibility around 96%, and it was successfully used to the determination of Amlodipine content in the pharmaceutical formulation. PMID:25281143

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

    Science.gov (United States)

    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. Polarization Induced Changes in LSM Thin Film Electrode Composition Observed by In Operando Raman Spectroscopy and TOF-SIMS

    DEFF Research Database (Denmark)

    McIntyre, Melissa D.; Walker, Robert; Traulsen, Marie Lund;

    2015-01-01

    an applied potential.1-3 The presented work explores the polarisation induced changes in LSM electrode composition by utilizing in operando Raman spectroscopy and post mortem ToF-SIMS depth profiling on LSM thin film model electrodes fabricated by pulsed laser deposition on YSZ substrates with a thin...

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

    Science.gov (United States)

    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.

  12. Biocompatible PEDOT:Nafion composite electrode coatings for selective detection of neurotransmitters in vivo.

    Science.gov (United States)

    Vreeland, Richard F; Atcherley, Christopher W; Russell, Wilfred S; Xie, Jennifer Y; Lu, Dong; Laude, Nicholas D; Porreca, Frank; Heien, Michael L

    2015-03-01

    A Nafion and poly(3,4-ethylenedioxythiophene) (PEDOT) containing composite polymer has been electropolymerized on carbon-fiber microelectrodes with the goal of creating a mechanically stable, robust, and controllable electrode coating that increases the selectivity and sensitivity of in vivo electrochemical measurements. The coating is deposited on carbon-fiber microelectrodes by applying a triangle waveform from +1.5 V to -0.8 V and back in a dilute solution of ethylenedioxythiophene (EDOT) and Nafion in acetonitrile. Scanning electron microscopy demonstrated that the coating is uniform and ∼100 nm thick. Energy-dispersive X-ray spectroscopy demonstrated that both sulfur and fluorine are present in the coating, indicating the incorporation of PEDOT (poly(3,4-ethylenedioxythiophene) and Nafion. Two types of PEDOT:Nafion coated electrodes were then analyzed electrochemically. PEDOT:Nafion-coated electrodes made using 200 μM EDOT exhibit a 10-90 response time of 0.46 ± 0.09 s versus 0.45 ± 0.11 s for an uncoated fiber in response to a 1.0 μM bolus of dopamine. The electrodes coated using a higher EDOT concentration (400 μM) are slower with a 10-90 response time of 0.84 ± 0.19 s, but display increased sensitivity to dopamine, at 46 ± 13 nA/μM, compared to 26 ± 6 nA/μM for the electrodes coated in 200 μM EDOT and 13 ± 2 nA/μM for an uncoated fiber. PEDOT:Nafion-coated electrodes were lowered into the nucleus accumbens of a rat, and both spontaneous and electrically evoked dopamine release were measured. In addition to improvements in sensitivity and selectivity, the coating dramatically reduces acute in vivo biofouling. PMID:25692657

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

    Science.gov (United States)

    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.

  14. Synthesis and electrochemical properties of three-dimensional graphene/polyaniline composites for supercapacitor electrode materials

    Institute of Scientific and Technical Information of China (English)

    赵文; 何大伟; 王永生; 杜翔; 忻昊

    2015-01-01

    To improve the specific capacitance and rate capability of electrode material for supercapacitors, a three-dimensional graphene/polyaniline (3DGN/PANI) composite is prepared via in situ polymerization on GN hydrogel. PANI grows on the GN surface as a thin film, and its content in the composite is controlled by the concentration of the reaction monomer. The specific capacitance of the 3DGN/PANI composite containing 10 wt%PANI reaches 322.8 F·g−1 at a current density of 1 A·g−1, nearly twice as large as that of the pure 3DGN (162.8 F·g−1). The capacitance of the composite is 307.9 F·g−1 at 30 A·g−1 (maintaining 95.4%), and 89%retention after 500 cycles. This study demonstrates the exciting potential of 3DGN/PANI with high capacitance, excellent rate capability and long cycling life for supercapacitors.

  15. Electrochemical behavior of thin-film Sm-doped ceria: insights from the point-contact configuration.

    Science.gov (United States)

    Oh, Tae-Sik; Haile, Sossina M

    2015-05-28

    The electrochemical behavior of chemical vapor deposition (CVD) grown porous films of Sm-doped ceria (SDC) for hydrogen oxidation has been evaluated by impedance spectroscopy using a point contact geometry at a temperature of 650 °C. Porous SDC films, 950 nm in thickness, were deposited on both sides of single-crystal YSZ(100). Pt paste was applied over the surface of one SDC layer to create a high-activity counter electrode. Ni wire was contacted to the surface of the other SDC layer to create a limited contact-area working electrode. The active area of contact at the working electrode was determined using the Newman equation and the electrolyte constriction impedance. The radius of this area varied from 5 to 18 μm, depending on gas composition and bias. The area-normalized electrode impedance (where the area was that determined as described above) varied from 0.03 to 0.17 Ω cm(2) and generally decreased with cathodic bias and decreasing oxygen partial pressure. From an analysis of the dimensions of the active area with bias, it was found that the majority of the overpotential occurred at the SDC|gas interface rather than the SDC|YSZ interface. Overall, the anode overpotential is found to be extremely small, competitive with the best oxide anodes reported in the literature. Nevertheless, the impedance falls in line with expected values based on extrapolations of the properties of dense, flat SDC model electrodes grown by pulsed laser deposition (Chueh et al., Nat. Mater., 2012). The results demonstrate that, with suitable fabrication approaches, exceptional activity can be achieved with SDC for hydrogen electrooxidation even in the absence of metal-oxide-gas triple phase boundaries. PMID:25932615

  16. Performance of a combined capacitor based on ultrafine nickel oxide/carbon nanotubes composite electrodes

    Institute of Scientific and Technical Information of China (English)

    Xiaofeng Wang; Yanqiu Cao; Yiqiang Lu; Qiqian Sha; Ji Liang

    2004-01-01

    A new sol-gel process for the preparation of ultrafine nickel hydroxide electrode materials was developed. The composite electrodes consisting of carbon nanotubes and Ni(OH)2 were developed by mixing the hydroxide and carbon nanotubes together in different mass ratios. In order to enhance energy density, a combined type pseudocapacitor/electric double layer capacitor was considered and its electrochemical properties were characterized by cyclic voltammetry and dc charge/discharge test. The combined capacitor shows excellent capacitor behavior with an operating voltage up to 1.6 V in KOH aqueous electrolyte. Stable charge/discharge behaviors were observed with much higher specific capacitance values of 24 F/g compared with that of EDLC (12F/g) by introducing 60% Ni(OH)2 in the anode material. By using the modified anode of a Ni(OH)2/carbon nanotubes composite electrode, the specific capacitance of the cell was less sensitive to discharge current density compared with that of the capacitor employing pure nickel hydroxide as anode. The combined capacitor in this study exhibits high energy density and stable power characteristics.

  17. Boron-doped MnO{sub 2}/carbon fiber composite electrode for supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Hong Zhong, E-mail: hzchi@hdu.edu.cn [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhu, Hongjie [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Gao, Linhui [Center of Materials Engineering, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2015-10-05

    Highlights: • Interstitial ion in MnO{sub 2} lattice. • Porous film composed by interlocking worm-like nanostructure. • Boron-doped birnessite-type MnO{sub 2}/carbon fiber composite electrode. • Enhanced capacitive properties through nonmetal element doping. - Abstract: The boron-doped MnO{sub 2}/carbon fiber composite electrode has been prepared via in situ redox reaction between potassium permanganate and carbon fibers in the presence of boric acid. The addition of boron as dopant results in the increase of growth-rate of MnO{sub 2} crystal and the formation of worm-like nanostructure. Based on the analysis of binding energy, element boron incorporates into the MnO{sub 2} lattice through interstitial mode. The doped electrode with porous framework is beneficial to pseudocapacitive reaction and surface charge storage, leading to higher specific capacitance and superior rate capability. After experienced 1000 cycles, the boron-doped MnO{sub 2} still retain a higher specific capacitance by about 80% of its initial value. The fall in capacitance is blamed to be the combination of the formation of soluble Mn{sup 2+} and the absence of active site on the outer surface.

  18. Boron-doped MnO2/carbon fiber composite electrode for supercapacitor

    International Nuclear Information System (INIS)

    Highlights: • Interstitial ion in MnO2 lattice. • Porous film composed by interlocking worm-like nanostructure. • Boron-doped birnessite-type MnO2/carbon fiber composite electrode. • Enhanced capacitive properties through nonmetal element doping. - Abstract: The boron-doped MnO2/carbon fiber composite electrode has been prepared via in situ redox reaction between potassium permanganate and carbon fibers in the presence of boric acid. The addition of boron as dopant results in the increase of growth-rate of MnO2 crystal and the formation of worm-like nanostructure. Based on the analysis of binding energy, element boron incorporates into the MnO2 lattice through interstitial mode. The doped electrode with porous framework is beneficial to pseudocapacitive reaction and surface charge storage, leading to higher specific capacitance and superior rate capability. After experienced 1000 cycles, the boron-doped MnO2 still retain a higher specific capacitance by about 80% of its initial value. The fall in capacitance is blamed to be the combination of the formation of soluble Mn2+ and the absence of active site on the outer surface

  19. Bi{sub 2}O{sub 3} with activated carbon composite as a supercapacitor electrode

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.X. [Institute of Chemical Power Sources, Soochow University, Suzhou 215006 (China); Jin, C.C., E-mail: jinsml@163.com [Institute of Chemical Power Sources, Soochow University, Suzhou 215006 (China); Qian, W.J. [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215006 (China)

    2014-12-05

    Highlights: • The AC–Bi{sub 2}O{sub 3} composite was synthesized by vacuum impregnation and roasting process. • The capacitance of AC–Bi{sub 2}O{sub 3} is 332.6 F g{sup −1} in 6 M KOH at specific current of 1 A g{sup −1}. • The capacitance of AC–Bi{sub 2}O{sub 3} is about 3 times larger than that of AC (106.5 F g{sup −1}). • The AC–Bi{sub 2}O{sub 3} electrode can keep 59% of initial capacitance over 1000 cycles. - Abstract: To improve the capacitance of activated carbon (AC) supercapacitors, the activated carbon–bismuth oxide (AC–Bi{sub 2}O{sub 3}) composite was synthesized by vacuum impregnation and roasting process. The morphology and phase structure of the AC–Bi{sub 2}O{sub 3} composite was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectrum (FTIR), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET). The electrochemical performance (cyclic voltammetry (CV), galvanostatic charge discharge tests and electrochemical impedance spectroscopy (EIS)) of the AC electrode and the AC–Bi{sub 2}O{sub 3} electrode was characterized on the electrochemical workstation. It was found that the capacitance of AC–Bi{sub 2}O{sub 3} composite is 332.6 F g{sup −1} in 6 M KOH by chronopotentiometry at a specific current of 1 A g{sup −1} and the specific capacitance is more than 3 times larger than that of activated carbon (106.5 F g{sup −1}) at the same condition. In addition, the composite also displays a low resistance and a good stability. These results show that AC–Bi{sub 2}O{sub 3} composite is a very promising electrode material for high-performance supercapacitors.

  20. Preparation and characterization of RuO2/polyaniline/polymer binder composite electrodes for supercapacitor applications

    Directory of Open Access Journals (Sweden)

    SUZANA SOPČIĆ

    2012-03-01

    Full Text Available The composite electrodes consisting of amorphous and hydrous RuO2, polyaniline and polymeric binder, Nafion® or poly(vinilydene fluoride were prepared. The electro¬chem-ical and pseudocapacitive properties of the prepared electrodes were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the responses of composite electrodes are very sensitive to the presence of individual components and their respective ratio in the mixture. The difference in the electro-chemical behavior was explained by the different physico-chemical properties of the polymeric binders.

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

    Directory of Open Access Journals (Sweden)

    Joop Schoonman

    2007-04-01

    Full Text Available An exfoliated graphite-polystyrene composite electrode was evaluated as analternative electrode in the oxidation and the determination of oxalic acid in 0.1 M Na2SO4supporting electrolyte. Using CV, LSV, CA procedures, linear dependences I vs. C wereobtained in the concentrations range of oxalic acid between 0.5 to 3 mM, with LOD =0.05mM, and recovery degree of 98%, without need of surface renewing between successiveruns. The accuracy of the methods was evaluated as excellent comparing the detection resultswith that obtained using conventional KMnO4 titration method. In addition, the apparentdiffusion coefficient of oxalic acid D was found to be around 2.89 · 10-8 cm2·s-1 by CA andCV.

  2. Laser annealed composite titanium dioxide electrodes for dye-sensitized solar cells on glass and plastics

    Science.gov (United States)

    Pan, Heng; Ko, Seung Hwan; Misra, Nipun; Grigoropoulos, Costas P.

    2009-02-01

    We report a rapid and low temperature process for fabricating composite TiO2 electrodes for dye-sensitized solar cells on glass and plastics by in tandem spray deposition and laser annealing. A homogenized KrF excimer laser beam (248 nm) was used to layer-by-layer anneal spray deposited TiO2 nanoparticles. The produced TiO2 film is crack free and contains small particles (30 nm) mixed with different fractions of larger particles (100-200 nm) controlled by the applied laser fluence. Laser annealed double-layered structure is demonstrated for both doctor-blade deposited and spray-deposited electrodes and performance enhancement can be observed. The highest demonstrated all-laser-annealed cells utilizing ruthenium dye and liquid electrolyte showed power conversion efficiency of ˜3.8% under simulated illumination of 100 mW/cm2.

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

    Science.gov (United States)

    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. PMID:22980574

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

    Science.gov (United States)

    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. Singler-chamber SOFCs based on gadolinia doped ceria operated on methane and propane; Pilas de combustible de una sola camara, basadas en electrolitos de ceria dopada con gadolinia y operadas con metano y propano

    Energy Technology Data Exchange (ETDEWEB)

    Morales, M.; Roa, J. J.; Capdevila, X. G.; Segarra, M.; Pinol, S.

    2010-07-01

    The main advantages of single-chamber solid oxide fuel cells (SOFCs) respect to dual-chamber SOFCs, are to simplify the device design and to operate in mixtures of hydrocarbon (methane, propane...) and air, with no separation between fuel and oxidant. However, this design requires the use of selective electrodes for the fuel oxidation and the oxidant reduction. In this work, electrolyte-supported SOFCs were fabricated using gadolinia doped ceria (GDC) as the electrolyte, Ni + GDC as the anode and LSC(La{sub 0}.5Sr{sub 0}.5CoO{sub 3}-{delta})-GDC-Ag{sub 2}O as the cathode. The electrical properties of the cell were determined in mixtures of methane + air and propane + air. The influence of temperature, gas composition and total flow rate on the fuel cell performance was investigated. As a result, the power density was strongly increased with increasing temperature, total flow rate and hydrocarbon composition. Under optimized gas compositions and total flow conditions, power densities of 70 and 320 mW/cm{sup 2} operating on propane at a temperature of 600 degree centigrade and methane (795 degree centigrade) were obtained, respectively. (Author)

  6. Assessment for the role of rare earth oxide in the R2O3 - RuO2 - Pt composite electrode

    International Nuclear Information System (INIS)

    Our work has showed several results related to assessment for the role of rare earth oxide in the R2O3 - RuO2 - Pt composite electrode. The precursor method was used for preparing composite electrode in the following forms: a- RuO2 - Pt electrode b- La2O3 (55%) - RuO2 (45%) - Pt electrode c- CeO2 (60%) - RuO2 (40%) - Pt electrode By measurements of anodic polarization and cyclic potential for the types of a, b, c electrodes we can see that the La2O3 (55%) - 45% RuO2 - Pt electrode will be the best anodic electrode. It means that the partial replacement of ruthenium oxide by lanthanum oxide in composite oxide electrode will be an effective one. (author)

  7. Electrochemical sensors based on binuclear cobalt phthalocyanine/surfactant/ordered mesoporous carbon composite electrode

    International Nuclear Information System (INIS)

    A new ordered mesoporous carbon (OMC) composite modified electrode was fabricated for the first time. Binuclear cobalt phthalocyaninehexasulfonate sodium salt (bi-CoPc) can be adsorbed onto didodecyldimethylammonium bromide (DDAB)/OMC film by ion exchange. UV-vis spectroscopy, scanning electron microscopy (SEM) and electrochemical methods were used to characterize the composite film. The cyclic voltammograms demonstrate that the charge transfer of bi-CoPc is promoted by the presence of OMC. Further study indicated that bi-CoPc/DDAB/OMC film is the excellent electrocatalyst for the electrochemical reduction of oxygen in a neutral aqueous solution and hemoglobin (Hb) at lower concentrations. Additionally, as an amperometric 2-mercaptoethanol (2-ME) sensor, this modified electrode shows a wider linear range (2.5 x 10-6 to 1.4 x 10-4 M), high sensitivity (16.5 μA mM-1) and low detection limit of 0.6 μM (S/N = 3). All these confirm the fact that the new composite film may have wide potential applications in biofuel cells, biological and environmental sensors.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    Highlights: • The composites of polyaniline nanofiber and large mesoporous carbon were prepared for supercapacitors. • The large mesoporous carbons were simply prepared by nano-CaCO3 template method. • The composites exhibit high capacitance and good rate capability and cycle stability. - Abstract: 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. Polyaniline nanofiber/large mesoporous carbon composites as electrode materials for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Huan; Xu, Bin; Jia, Mengqiu, E-mail: jiamq@mail.buct.edu.cn; Zhang, Mei; Cao, Bin; Zhao, Xiaonan; Wang, Yu

    2015-03-30

    Highlights: • The composites of polyaniline nanofiber and large mesoporous carbon were prepared for supercapacitors. • The large mesoporous carbons were simply prepared by nano-CaCO{sub 3} template method. • The composites exhibit high capacitance and good rate capability and cycle stability. - Abstract: 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-CaCO{sub 3} 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{sup −1} at a current load of 0.1 A g{sup −1} with good rate performance and cycling stability, suggesting its potential application in the electrode material for supercapacitors.

  11. Sulphur-polypyrrole composite positive electrode materials for rechargeable lithium batteries

    International Nuclear Information System (INIS)

    A novel conducting sulphur-polypyrrole composite material was prepared by the chemical polymerization method with sodium p-toluenesulphonate as the dopant, 4-styrenesulphonic sodium salts as the surfactant, and FeCl3 as the oxidant. The new material was characterized by Raman spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Nanosize polypyrrole particles were uniformly coated onto the surface of the sulphur powder, which significantly improved the electrical conductivity, the capacity and the cycle durability in a lithium cell compared with the bare sulphur electrode

  12. Voltammetric determination of theophylline at a Nafion/multi-wall carbon nanotubes composite film-modified glassy carbon electrode

    Indian Academy of Sciences (India)

    Suling Yang; Ran Yang; Gang Li; Jianjun Li; Lingbo Qu

    2010-11-01

    A Nafion/multi-wall carbon nanotubes (MWNTs) composite film-modified electrode was fabricated and applied to the sensitive and convenient determination of theophylline (TP). Multi-wall carbon nanotubes (MWNTs) were easily dispersed homogeneously into 0.1% Nafion methanol solution by sonication. Appropriate amount of Nafion/MWNTs suspension was coated on a glassy carbon electrode. After evaporating methanol, a Nafion/MWNTs composite film-modified electrode was achieved. TP could effectively accumulate at Nafion/MWNTs composite film-modified electrode and cause a sensitive anodic peak at around 1180 mV (vs SCE) in 0.01 mol/L H2SO4 medium (pH 1.8). In contrast with the bare glassy carbon electrode, Nafion film-modified electrode, Nafion/MWNTs film-modified electrode could remarkably increase the anodic peak current and decreased the overpotential of TP oxidation. Under the optimized conditions, the anodic peak current was proportional to TP concentration in the range of 8.0 × 10-8-6.0 × 10-5 mol/L, with a detection limit of 2.0 × 10-8 mol/L. This newly developed method was used to determine TP in drug samples with good percentage of recoveries.

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

    Science.gov (United States)

    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. PMID:24615460

  14. Preparation and CO conversion activity of ceria nanotubes by carbon nanotubes templating method

    Institute of Scientific and Technical Information of China (English)

    FANG Jianhui; CAO Zhiyuan; ZHANG Dengsong; SHEN Xia; DING Weizhong; SHI Liyi

    2008-01-01

    Ceria nanotubes with high CO conversion activity by means of carbon nanotubes as removable templates in the simple liquid phase process were fabricated under moderate conditions. The pristine CNTs were first pretreated by refluxing in a 30% nitric acid solution at 140 °C for 24 h, then dispersed in an ethanolic Ce(NO3)3·6H2O solution with ultrasonic radiation at room temperature for 1 h. Under vigorous stirring, NaOH solution was added drop by drop into the above ethanolic solution until the pH value was 10. The product was collected and repeatedly washed with ethanol and on drying at 60 °C, the CeO2/CNT composites were obtained. Then, the as-prepared composites were heated at 450 °C in an air atmosphere for 30 min to remove CNTs. The ceria nanotubes were characterized by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and X-Ray Photoelectron Spectrum (XPS). The results showed that the ceria nanotubes were polycrystalline face-centered cubic phase and were composed of lots of dense ceria nanoparticles. The diameter of ceria nanotubes was about 40-50 nm. Catalytic activity of the product for CO oxidation was carried out at the region of 30-300 °C in a U-shaped quartz reactor with feeding about 0.15 g of the catalyst, which was loaded on Al2O3 carrier. The inlet gas composition was 1.0% CO and 28% O2 with N2 as balance, and the rate of flow was kept at 40 ml/min. The catalytic products were analyzed by gas chromatography. The as-prepared CeO2 nanotubes showed higher CO oxidation activity, which indicated that the morphology of ceria products affected the catalytic performance. The ceria nanotubes supported on Al2O3 demonstrated that conversion temperature for CO oxidation to CO2 was lower than that for bulk catalysts.

  15. Catalysis by ceria and related materials

    CERN Document Server

    Trovarelli, Alessandro

    2002-01-01

    The use of CeO2-based materials in catalysis has attracted considerable attention in recent years, particularly in applications like environmental catalysis, where ceria has shown great potential. This book critically reviews the most recent advances in the field, with the focus on both fundamental and applied issues. The first few chapters cover structural and chemical properties of ceria and related materials, i.e. phase stability, reduction behaviour, synthesis, interaction with probe molecules (CO, O2, NO), and metal-support interaction - all presented from the viewpoint of catalytic appl

  16. Solvothermal Synthesis of Ni/Reduced Graphene Oxide Composites as Electrode Material for Supercapacitors

    International Nuclear Information System (INIS)

    Highlights: • Ni/RGO composites were successfully synthesized through a simple solvothermal method. • The attached Ni nanoparticles can efficiently inhibit the aggregation of RGO nanosheets and provide pseudocapacitance. • Ni/RGO–2 exhibits the highest specific capacitance of 547.3 F g−1 at 1 A g−1 in 2 M KOH. • Ni/RGO–2 can maintain 81% of initial capacity after a continuous 1000 times of cycling. - Abstract: A series of Ni/reduced graphene oxide (Ni/RGO) composites were synthesized through a simple solvothermal method. Detailed characterizations of the composite using transmission electron microscopy and field emission scanning electron microscopy indicated that Ni particles were uniformly dispersed on the RGO surfaces. The electrochemical performances of Ni/RGO composites were much higher than their counterparts of Ni and RGO, because of the Ni particles being firmly decorated with the RGO nanosheets and the synergistic effect between both components. Among the prepared composites, Ni/RGO–2 exhibits the best electrochemical performance; namely, a high specific capacitance of 547.3 F g−1 is obtained in 2 M KOH at 1 A g−1 and 81% of initial value is remained after a continuous cycling of 1000 times, which make it to be a promising electrode material for supercapacitors

  17. Graphene/vanadium oxide nanotubes composite as electrode material for electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Meimei [College of Chemistry, Xiangtan University, Xiangtan 411005 (China); College of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); Ge, Chongyong [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); College of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); Hou, Zhaohui, E-mail: zhqh96@163.com [College of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); Cao, Jianguo [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); College of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); He, Binhong [College of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); Zeng, Fanyan [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); College of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006 (China); Kuang, Yafei, E-mail: yafeik@163.com [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

    2013-07-15

    Graphene/vanadium oxide nanotubes (VOx-NTs) composite was successfully synthesized through the hydrothermal process in which acetone as solvent and 1-hexadecylamine (HDA) as structure-directing template were used. Morphology, structure and composition of the as-obtained composite were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, nitrogen isothermal adsorption/desorption and thermo gravimetric analysis (TGA). The composite with the VOx-NTs amount of 69.0 wt% can deliver a specific capacitance of 210 F/g at a current density of 1 A/g in 1 M Na{sub 2}SO{sub 4} aqueous solution, which is nearly twice as that of pristine graphene (128 F/g) or VOx-NTs (127 F/g), and exhibit a good performance rate. Compared with pure VOx-NTs, the cycle stability of the composite was also greatly improved due to the enhanced conductivity of the electrode and the structure buffer role of graphene.

  18. Electrochemical properties of graphene nanosheets/polyaniline nanofibers composites as electrode for supercapacitors

    Science.gov (United States)

    Li, Jing; Xie, Huaqing; Li, Yang; Liu, Jie; Li, Zhuxin

    Graphene nanosheets/polyaniline nanofibers (GNS/PANI) composites are synthesized via in situ polymerization of aniline monomer in HClO 4 solution. The PANI nanofibers homogeneously coating on the surface of GNS greatly improve the charge transfer reaction. The GNS/PANI composites exhibit better electrochemical performances than the pure individual components. A remarkable specific capacitance of 1130 F g -1 (based on GNS/PANI composites) is obtained at a scan rate of 5 mV s -1 in 1 M H 2SO 4 solution compared to 402 F g -1 for pure PANI and 270 F g -1 for GNS. The excellent performance is not only due to the GNS which can provide good electrical conductivity and high specific surface area, but also associate with a good redox activity of ordered PANI nanofibers. Moreover, the GNS/PANI composites present excellent long cycle life with 87% specific capacitance retained after 1000 charge/discharge processes. The resulting composites are promising electrode materials for high-performance electrical energy storage devices.

  19. Graphene/vanadium oxide nanotubes composite as electrode material for electrochemical capacitors

    International Nuclear Information System (INIS)

    Graphene/vanadium oxide nanotubes (VOx-NTs) composite was successfully synthesized through the hydrothermal process in which acetone as solvent and 1-hexadecylamine (HDA) as structure-directing template were used. Morphology, structure and composition of the as-obtained composite were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, nitrogen isothermal adsorption/desorption and thermo gravimetric analysis (TGA). The composite with the VOx-NTs amount of 69.0 wt% can deliver a specific capacitance of 210 F/g at a current density of 1 A/g in 1 M Na2SO4 aqueous solution, which is nearly twice as that of pristine graphene (128 F/g) or VOx-NTs (127 F/g), and exhibit a good performance rate. Compared with pure VOx-NTs, the cycle stability of the composite was also greatly improved due to the enhanced conductivity of the electrode and the structure buffer role of graphene

  20. Preparation of TiO2-based nanotubes/nanoparticles composite thin film electrodes for their electron transport properties

    International Nuclear Information System (INIS)

    The composite thin film electrodes were prepared with one-dimensional (1D) TiO2-B nanotubes (NTs) and zero-dimensional TiO2 nanoparticles (NPs) based on different weight ratios. The electron transport properties of the NTs/NPs composite thin film electrodes applied for dye-sensitized solar cells had been investigated systematically. The results indicated that although the amount of dye adsorption decreased slightly, the devices with the NTs/NPs composite thin film electrodes could obtain higher open-circuit voltage and overall conversion efficiency compared to devices with pure TiO2 NPs electrodes by rational tuning the weight ratio of TiO2-B NTs and TiO2 NPs. When the weight ratio of TiO2-B NTs in the NTs/NPs composite thin film electrodes increased, the density of states and recombination rate decreased. The 1D structure of TiO2-B NTs can provide direct paths for electron transport, resulting in higher electron lifetime, electron diffusion coefficient and electron diffusion length. The composite thin film electrodes possess the merits of the rapid electron transport of TiO2-B NTs and the high surface area of TiO2 NPs, which has great applied potential in the field of photovoltaic devices. - Highlights: • The composite thin film electrodes (CTFEs) were prepared with nanotubes and nanoparticles. • The CTFEs possess the rapid electron transport and high surface area. • The CTFEs exhibit lower recombination rate and longer electron life time. • The CTFEs have great applied potential in the field of photovoltaic devices

  1. Characterization of gadolinia-doped ceria with manganese addition synthesized by the cation complexation technique

    International Nuclear Information System (INIS)

    Ceria-based compounds may be used for several technological applications like catalysts, grinding media and materials for electrolyte and electrodes in solid oxide fuel cells. For most of these applications fine powders are required. In this work, nanostructured ceria powders containing 20 mol % gadolinia with and without manganese addition were synthesized by the cation complexation technique. The prepared powders were calcined at 600 deg C for thermal decomposition of the metal citrate precursors. Results of X-ray diffraction, scanning electron microscopy and specific surface area evidenced the role of manganese on physical characteristics of the nanostructured materials. The cation complexation technique revealed to be a promising method for obtaining nanostructured powders with high yield and suitable physical properties for several technological applications. (author)

  2. Flexible Electrode Design: Fabrication of Freestanding Polyaniline-Based Composite Films for High-Performance Supercapacitors.

    Science.gov (United States)

    Khosrozadeh, Ali; Darabi, Mohammad Ali; Xing, Malcolm; Wang, Quan

    2016-05-11

    Polyaniline (PANI) is a promising pseudocapacitance electrode material. However, its structural instability leads to low cyclic stability and limited rate capability which hinders its practical applications. In view of the limitations, flexible PANI-based composite films are developed to improve the electrochemical performance of electrode materials. We report in the research a facile and cost-effective approach for fabrication of a high-performance supercapacitor (SC) with excellent cyclic stability and tunable energy and power densities. SC electrode containing a very high mass loading of active materials is a flexible film of PANI, tissue wiper-based cellulose, graphite-based exfoliated graphite (ExG), and silver nanoparticles with potential applications in wearable electronics. The optimum preparation weight ratios of silver nitrate/aniline and ExG/aniline used in the research are estimated to be 0.18 and 0.65 (or higher), respectively. Our results show that an ultrahigh capacitance of 3.84 F/cm(2) (240.10 F/g) at a discharge rate of 5 mA can be achieved. In addition, our study shows that the power density can be increased from 1531.3 to 3000 W/kg by selecting the weight ratio of ExG/aniline to be more than 0.65, with a sacrifice in the energy density. The obtained promising electrochemical properties are found to be mainly attributed to an effective combination of PANI, ExG, cushiony cellulose scaffold, and silver as well as the porosity of the composite. PMID:27116563

  3. Statistical thermodynamics of non-stoichiometric ceria and ceria zirconia solid solutions.

    Science.gov (United States)

    Bulfin, B; Hoffmann, L; de Oliveira, L; Knoblauch, N; Call, F; Roeb, M; Sattler, C; Schmücker, M

    2016-08-17

    The thermodynamic redox properties of ceria and ceria zirconia solid solutions are analysed with a new methodology for modelling such systems based on the statistical mechanics of lattice configurations. Experimental thermogravimetric equilibrium data obtained for small non-stoichiometry measurements are combined with literature data to cover a large range of non-stoichiometry (CeO2-δ, δ = 0.001-0.32), temperature (1073-1773 K) and oxygen partial pressure (1-10(-13) bar). A dilute species model of defect clusters , obeying the law of mass action, was sufficient to describe the system over the whole range of conditions, leading to a simple analytical equation of state for the system. This offers new physical insight into the redox properties of ceria based materials, and the theoretical methods developed should also be of great interest for other materials which exhibit continuous oxygen non-stoichiometry similar to ceria, such as perovskite oxides. PMID:27494765

  4. Reactive Mechanisms of LSCF Single-Phase and LSCF-CGO Composite Electrodes Operated in Anodic and Cathodic Polarisations

    International Nuclear Information System (INIS)

    An in-house model for a MIEC or MIEC-CGO composite has been built in order to analyse the electrode operating mechanisms in anodic and cathodic polarisations (SOEC and SOFC modes). A special attention has been paid to take into account the electrode microstructure properties as well as the most likely processes occurring therein. The reactive pathway has been divided in a sequence of reaction steps with a first oxidoreduction at the gas/MIEC surface, and a second one in parallel at the electrode TPBs. The model has been calibrated on experimental data recorded at 800 °C on a LSCF electrode tested in a symmetrical test configuration. A good agreement was found between simulated and experimental polarisation curves by using the electrode microstructural properties extracted from a 3D reconstruction obtained by FIB-SEM tomography. Considering the LSCF single-phase electrode, simulation results have highlighted that the reactive pathway is governed by the oxygen exchange at the gas/MIEC surface in cathodic polarisation. The mechanism is found to remain unchanged at low anodic polarisation, whereas oxidation at TPBs becomes the predominant reactive pathway at higher polarisation. For the LSCF-CGO composite, simulations have shown that the reactive mechanism is governed by the charge transfer at TPBs whatever the electrode polarisation. Thanks to sensitivity analysis, the rate-limiting steps of the different reactive pathways are also discussed

  5. Polarization Induced Changes in LSM Thin Film Electrode Composition Observed by In Operando Raman Spectroscopy and TOF-SIMS

    DEFF Research Database (Denmark)

    McIntyre, Melissa D.; Traulsen, Marie Lund; Norrman, Kion;

    2015-01-01

    electrical polarizations. Raman spectra recorded during polarization showed shifts in spectral intensities that were both reversible and dependent on the applied potential. Spectral changes were assigned to changes in the LSM electronic structure that resulted from changing oxide concentrations in the near......-surface region. Ex situ TOF-SIMS depth profiles were recorded through the LSM electrodes and revealed distinct compositional changes throughout the electrodes. The electrode elements and impurities separated into well-defined layers that were more stratified for stronger applied polarizations. The mechanism...

  6. Hydrodeoxygenation of Guaiacol over Ceria-Zirconia Catalysts.

    Science.gov (United States)

    Schimming, Sarah M; LaMont, Onaje D; König, Michael; Rogers, Allyson K; D'Amico, Andrew D; Yung, Matthew M; Sievers, Carsten

    2015-06-22

    The hydrodeoxygenation of guaiacol is investigated over bulk ceria and ceria-zirconia catalysts with different elemental compositions. The reactions are performed in a flow reactor at 1 atm and 275-400 °C. The primary products are phenol and catechol, whereas cresol and benzene are formed as secondary products. No products with hydrogenated rings are formed. The highest conversion of guaiacol is achieved over a catalyst containing 60 mol % CeO2 and 40 mol % ZrO2 . Pseudo-first-order activation energies of 97-114 kJ mol(-1) are observed over the mixed metal oxide catalysts. None of the catalysts show significant deactivation during 72 h on stream. The important physicochemical properties of the catalysts are characterized by X-ray diffraction (XRD), temperature-programmed reduction, titration of oxygen vacancies, and temperature-programmed desorption of ammonia. On the basis of these experimental results, the reasons for the observed reactivity trends are identified. PMID:26036450

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

    Science.gov (United States)

    Arcila Velez, Margarita Rosa

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

  8. Graphene ceramic composite as a new kind of surface-renewable electrode: application to the electroanalysis of ascorbic acid

    International Nuclear Information System (INIS)

    This study introduces a new surface-renewable electrode based on a sol–gel derived graphene ceramic composite. The electrode was prepared by dispersing graphene nanosheets into a solution of the sol–gel precursors containing methyl triethoxysilane in methanol and hydrochloric acid. During hydrolysis of methyl triethoxysilane, the graphene nanosheets are trapped in the gel. After moulding and drying the composite, it can be used as a surface-renewable electrode to which we refer as a graphene ceramic composite electrode (GCCE). Cyclic voltammograms of the hexacyanoferrate(II/III) model redox system at the GCCE were compared to those obtained with a conventional carbon ceramic electrode and showed a highly improved electron transfer rate at the GCCE. The electrocatalytic oxidation of ascorbic acid as a model analyte was then studied at working potential of 50 mV and over the 3–84 μM concentration range. It revealed a sensitivity of 6.06 μA μM−1 cm−2 and a detection limit of 0.82 μM. The GCCE was successfully applied to the determination of ascorbic acid in orange juice and urine samples. Advantages such as good mechanical and chemical stability, ease of fabrication, and reproducible preparation make the GCCE a potentially useful and widely applicable renewable electrode for use in routine analysis. (author)

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

    International Nuclear Information System (INIS)

    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. (paper)

  10. Structural characterization of hexadecyltrimethylammonium-smectite composites and their potentiometric electrode applications

    Energy Technology Data Exchange (ETDEWEB)

    Cubuk, Osman [Department of Chemistry, Faculty of Arts and Sciences, Erzincan University, 24100 Erzincan (Turkey); Caglar, Bulent, E-mail: bcaglar55@gmail.com [Department of Chemistry, Faculty of Arts and Sciences, Erzincan University, 24100 Erzincan (Turkey); Topcu, Cihan; Coldur, Fatih; Sarp, Gokhan [Department of Chemistry, Faculty of Arts and Sciences, Erzincan University, 24100 Erzincan (Turkey); Tabak, Ahmet [Department of Chemistry, Faculty of Arts and Sciences, Recep Tayyip Erdoğan University, 53100 Rize (Turkey); Sahin, Erdal [Department of Chemistry, Faculty of Arts and Sciences, Erzincan University, 24100 Erzincan (Turkey)

    2015-05-30

    Graphical abstract: - Highlights: • Surfactant cations intercalated with different molecular arrangements into smectite layers. • The electrophoretic mobility values indicate that excess surfactant loadings also create positive charges on the organosmectites surfaces. • A novel potentiometric SCN{sup −} selective electrode was fabricated based on modified smectite. - Abstract: Organosmectites were prepared by the intercalation of hexadecyltrimethylammonium cations at various ratios into interlayer of Unye smectite. Structural, thermal, morphological and textural properties of the synthesized organosmectites were characterized. Afterwards, a novel potentiometric PVC-membrane thiocyanate selective electrode was prepared based on the obtained hexadecyltrimethylammonium modified smectites as electroactive material. The basal spacing values of organosmectites were observed in the range of 15.61 and 35.50 Å. Powder X-ray diffraction data show that the surfactant cations penetrated into the smectite layers with different molecular arrangements. Modification of smectite with hexadecyltrimethylammonium led to appreciable decreases in the intensities of the FTIR bands at 3402 and 1635 cm{sup −1} and the new characteristic vibrational bands at 2927, 2850, 1472 and 722 cm{sup −1} originating from the surfactant molecules appeared. The thermal analysis data showed that the decomposition of surfactant species occurred in the temperature range of 170–720 °C and the amount of dehydrated water gradually decreased with the increase in surfactant amount. The intercalation of surfactant species within the gallery spacing led gradually to smaller surface areas. In addition, the electrophoretic mobility values indicate that excess surfactant loadings also generate positive charges on the organosmectite surfaces. The most convenient membrane composition resulting in the best potentiometric performance was investigated. The optimum membrane composition was determined to

  11. Structural characterization of hexadecyltrimethylammonium-smectite composites and their potentiometric electrode applications

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Surfactant cations intercalated with different molecular arrangements into smectite layers. • The electrophoretic mobility values indicate that excess surfactant loadings also create positive charges on the organosmectites surfaces. • A novel potentiometric SCN− selective electrode was fabricated based on modified smectite. - Abstract: Organosmectites were prepared by the intercalation of hexadecyltrimethylammonium cations at various ratios into interlayer of Unye smectite. Structural, thermal, morphological and textural properties of the synthesized organosmectites were characterized. Afterwards, a novel potentiometric PVC-membrane thiocyanate selective electrode was prepared based on the obtained hexadecyltrimethylammonium modified smectites as electroactive material. The basal spacing values of organosmectites were observed in the range of 15.61 and 35.50 Å. Powder X-ray diffraction data show that the surfactant cations penetrated into the smectite layers with different molecular arrangements. Modification of smectite with hexadecyltrimethylammonium led to appreciable decreases in the intensities of the FTIR bands at 3402 and 1635 cm−1 and the new characteristic vibrational bands at 2927, 2850, 1472 and 722 cm−1 originating from the surfactant molecules appeared. The thermal analysis data showed that the decomposition of surfactant species occurred in the temperature range of 170–720 °C and the amount of dehydrated water gradually decreased with the increase in surfactant amount. The intercalation of surfactant species within the gallery spacing led gradually to smaller surface areas. In addition, the electrophoretic mobility values indicate that excess surfactant loadings also generate positive charges on the organosmectite surfaces. The most convenient membrane composition resulting in the best potentiometric performance was investigated. The optimum membrane composition was determined to have 20.0% (w/w) 2

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

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

    OpenAIRE

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

    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 characteriz...

  16. RuO2/Graphene composites for super-capacitor electrodes

    Science.gov (United States)

    Amir, Fatima; Ramlall, Tariq; Forest, Rebecca

    2013-03-01

    Metal oxides/graphene composites show significant improvement in their electrochemical proprieties compared to their individual constituents, such as high capacity, high rate capability and excellent cycling stability. Ruthenium dioxide (RuO2) has been recognized as an important electrode material for water electrolysis, oxygen reduction, and super-capacitors. A crucial aspect of all these applications is their structural, morphological and electrical properties. We have synthesized RuO2 from hydrolysis and oxidation of ruthenium tri-chloride RuCl3, which we physically mixed to graphene and used to coat tungsten substrates. For comparison, we also have deposited commercial RuO2 hydrate mixed with graphene on tungsten. The samples were then annealed at different temperatures. The effect of temperature has been studied in detail. Surface morphology analysis using a scanning electron microscope (SEM) shows smaller grain size at temperatures higher than 180 C. Structural properties obtained by using x-ray diffraction revealed an amorphous structure at temperatures lower than 180 C. The supercapacitance of the RuO2/graphene electrode is found to be dependent on the surface morphology. This project was supported by the Clare Booth Luce Foundation

  17. Electrocatalytic oxidation of hydrazine by copper iodide modified sol-gel derived carbon-ceramic composite Electrode

    Directory of Open Access Journals (Sweden)

    Ghasem Karim-Nezhad

    2014-03-01

    Full Text Available A new sol-gel derived ceramic-carbon composite electrode was fabricated by the use of CuI as modifier. The electrocatalytic activity of the copper iodide modified sol-gel derived ceramic-carbon composite (CIM-SGD-CCC electrode was examined for the oxidation of hydrazine. Cyclic voltammetry was employed to study the electrochemical and electrocatalytic properties of the modified electrode. Results showed that the CIM-SGD-CCC electrode has very high catalytic activity for electrooxidation of hydrazine. This proves that the copper iodide bears the main role in electro-catalytic oxidation of hydrazine. This modified electrode shows fast amperometric response with the range from 1 μ mol L-1 to 40 μ mol L-1 and the limit of detection (LOD of 0.524 μ mol L-1 for hydrazine. The relative standard deviation (R.S.D. was 0.72 % for 5 successive assays. High stability, good reproducibility, rapid response, easy surface regeneration and fabrication are the important characteristics of the proposed electrode.

  18. Surface Modification of Silver Nanowires for Morphology and Processing Control in Composite Transparent Electrodes.

    Science.gov (United States)

    Liang, Zhiming; Graham, Kenneth R

    2015-10-01

    Silver nanowires are attractive components for a number of materials and applications, including silver nanowire (AgNW)-polymer composites, electrically conductive coatings, and transparent electrodes. In this manuscript, the ability of thiols with hydrophobic to ionic end groups to bind to AgNW surfaces is investigated, followed by how the polarity of the surface modifying thiol influences the morphological and electrical properties of both AgNW/PEDOT:PSS blend films and pure AgNW networks. Utilizing surface modification of AgNWs with sodium 3-mercapto-1-propanesulfonate (MPS), morphologically homogeneous AgNW/PEDOT:PSS thin films with an order of magnitude lower sheet resistance at similar transmittance values than unmodified AgNWs are obtained with a one-step processing method. Brief optimization of MPS-AgNW/PEDOT:PSS blends yields a sheet resistance of 22.6 Ω/□ at 81.4% transmittance. PMID:26389535

  19. In situ synthesis of ceria nanoparticles in the ordered mesoporous carbon as a novel electrochemical sensor for the determination of hydrazine

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yue [College of Chemistry, Nankai University, 94 WeiJin Road, Tianjin 300071 (China); Li, Yijun, E-mail: yijunli@nankai.edu.cn [Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300071 (China); College of Chemistry, Nankai University, 94 WeiJin Road, Tianjin 300071 (China); He, Xiwen [College of Chemistry, Nankai University, 94 WeiJin Road, Tianjin 300071 (China)

    2014-03-01

    Highlights: • CeO{sub 2}–OMC composites were prepared via a hydrothermal method. • CeO{sub 2}–OMC had electrocatalytic ability to oxidation of hydrazine. • The sensor had high sensitivity, excellent stability and reproducibility. • The sensor was successfully employed to detect hydrazine in real water samples. - Abstract: A novel ceria (CeO{sub 2})–ordered mesoporous carbon (OMC) modified electrode for the sensitive amperometric determination of hydrazine was reported. CeO{sub 2}–OMC composites were synthesized via a hydrothermal method at a relatively low temperature (180 °C) and characterized by scanning electron microscopy (SEM), transmission electron microcopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The CeO{sub 2}–OMC modified glassy carbon electrode was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) and indicated good electrocatalytic effect to the oxidation of hydrazine. Under the optimized conditions, the present sensor could be used to measure hydrazine in wide linear range from 40 nM to 192 μM (R{sup 2} = 0.999) with a low detection limit of 12 nM (S/N = 3). Additionally, the sensor has been successfully applied to detect hydrazine in real water samples and the recoveries were between 98.2% and 105.6%. Eventually, the sensor exhibited an excellent stability and reproducibility as a promising method for determination of hydrazine.

  20. RuO2/Activated Carbon Composite Electrode Prepared by Modified Colloidal Procedure and Thermal Decomposition Method

    Science.gov (United States)

    Li, Xiang; Zheng, Feng; Gan, Weiping; Luo, Xun

    2016-01-01

    RuO2/activated carbon (AC) composite electrode was prepared by a modified colloidal procedure and a thermal decomposition method. The precursor for RuO2/AC was coated on tantalum sheet and annealed at 150°C to 190°C for 3 h to develop thin-film electrode. The microstructure and morphology of the RuO2/AC film were characterized by thermogravimetric analysis (TGA), x-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). The TGA results showed the maximum loss of RuO2/AC composite film at 410°C, with residual RuO2 of 23.17 wt.%. The amorphous phase structure of the composite was verified by XRD analysis. SEM analysis revealed that fine RuO2 particles were dispersed in an activated carbon matrix after annealing. The electrochemical properties of RuO2/AC electrode were examined by cycling voltammetry, galvanostatic charge-discharge, and cyclic behavior measurements. The specific capacitance of RuO2/AC electrode reached 245 F g-1. The cyclic behavior of RuO2/AC electrode was stable. Optimal annealing was achieved at 170°C for 3 h.

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Taer, E.; Awitdrus,; Farma, R. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Department of Physics, Faculty of Mathematics and Natural Sciences, University of Riau, 28293 Pekanbaru, Riau (Indonesia); Deraman, M., E-mail: madra@ukm.my; Talib, I. A.; Ishak, M. M.; Omar, R.; Dolah, B. N. M.; Basri, N. H.; Othman, M. A. R. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Kanwal, S. [ICCBS, H.E.J. Research Institute of Chemistry, University of Karachi, 75270 Karachi (Pakistan)

    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.

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

    Science.gov (United States)

    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.

  4. Study on the CO Oxidation over Ceria-Based Nanocatalysts.

    Science.gov (United States)

    Piumetti, Marco; Andana, Tahrizi; Bensaid, Samir; Russo, Nunzio; Fino, Debora; Pirone, Raffaele

    2016-12-01

    A series of ceria nanocatalysts have been prepared to study the structure dependency of the CO oxidation reaction. The ceria samples with well-defined nanostructures (nanocubes/Ce-NC and nanorods/Ce-NR) have been prepared using the hydrothermal method. Mesoporous ceria (Ce-MES) and ceria synthesized with solution combustion technique (Ce-SCS) have also been prepared for comparison. The lowest CO oxidation temperature has been reached by using ceria nanocubes (Ce-NC). This high activity draws immense contributions from the highly reactive (100) and (110) surfaces of the truncated nanocubes. The Ce-MES and Ce-SCS samples, despite their high surface areas, are unable to outdo the activity of Ce-NC and Ce-NR due to the abundant presence of (111) crystalline planes. This finding confirms the structure sensitivity of CO oxidation reaction catalyzed with ceria. PMID:27009532

  5. Gadolinia-Doped Ceria Cathodes for Electrolysis of CO2

    Science.gov (United States)

    Adler, Stuart B.

    2009-01-01

    Gadolinia-doped ceria, or GDC, (Gd(0.4)Ce(0.6)O(2-delta), where the value of delta in this material varies, depending on the temperature and oxygen concentration in the atmosphere in which it is being used) has shown promise as a cathode material for high-temperature electrolysis of carbon dioxide in solid oxide electrolysis cells. The polarization resistance of a GDC electrode is significantly less than that of an otherwise equivalent electrode made of any of several other materials that are now in use or under consideration for use as cathodes for reduction of carbon dioxide. In addition, GDC shows no sign of deterioration under typical temperature and gas-mixture operating conditions of a high-temperature electrolyzer. Electrolysis of CO2 is of interest to NASA as a way of generating O2 from the CO2 in the Martian atmosphere. On Earth, a combination of electrolysis of CO2 and electrolysis of H2O might prove useful as a means of generating synthesis gas (syngas) from the exhaust gas of a coal- or natural-gas-fired power plant, thereby reducing the emission of CO2 into the atmosphere. The syngas a mixture of CO and H2 could be used as a raw material in the manufacture, via the Fisher-Tropsch process, of synthetic fuels, lubrication oils, and other hydrocarbon prod

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

    Science.gov (United States)

    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

  7. Electrodeposited Mn3O4-NiO-Co3O4 as a composite electrode material for electrochemical capacitor

    International Nuclear Information System (INIS)

    Highlights: • Composite electrodes were synthesized by in situ electrodeposition method. • The highest specific capacitance of composite electrode is 7404 F g−1. • The power density of composite electrode is 99 kW kg−1 at current density of 20 A g−1. • The addition of K3Fe(CN)6 in KOH electrolyte has improved the electrochemical performance. - Abstract: A simple and easy galvanostatic electrodeposition method is used to synthesise a composite electrode consisting of manganese oxide (Mn3O4), nickel oxide (NiO) and cobalt oxide (Co3O4). The influence of Co3O4 on the morphology of fixed Mn3O4-NiO particles is investigated with a field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). The nature and elemental of the composite are examined by means of X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). The electrochemical performances of an Mn3O4-NiO-Co3O4 nanostructure/SS composite electrode are studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (CD) in various electrolytes, i.e. 0.5 M Na2SO4, 0.5 M KOH, 0.5 M Na2SO4/0.04 M K3Fe(CN)6 and 0.5 M KOH/0.04 M K3Fe(CN)6 electrolytes. The composite electrode prepared from 0.15 M Co deposition solution exhibits the optimum specific capacitance of 7404 F g−1 with high energy and power density of 1028 Wh kg−1 and 99 kW kg−1 at 20 A g−1 in mix KOH/0.04 M K3Fe(CN)6 electrolyte, respectively. The results show that the incorporation of K3Fe(CN)6 in KOH electrolyte influences the capacitance of Mn3O4-NiO-Co3O4 composite electrodes

  8. Electrocatalytic oxidation of phenol using Ni-Al{sub 2}O{sub 3} composite-coating electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud, S.S. [Chemistry Department, University College for Women for Arts, Science and Education, Ain Shams University, Heliopolis, Cairo (Egypt)], E-mail: drsohairr@hotmail.com; Ahmed, M.M. [Chemistry Department, University College for Women for Arts, Science and Education, Ain Shams University, Heliopolis, Cairo (Egypt)

    2009-05-27

    Electrocatalytic oxidation of phenol on Ni-Al{sub 2}O{sub 3} composite electrodes was investigated in wastewater. Firstly Ni-Al{sub 2}O{sub 3} composite-coating electrodes was prepared by electrodeposition of Ni-Al{sub 2}O{sub 3} composite on the mild steel substrates from the citrate bath containing NiSO{sub 4} as a source of nickel and alumina particles. The electrodeposited composite coating was heat treated at 400 deg. C and characterized by using different techniques such as scanning electron microscope (SEM), electron dispersive X-ray analysis (EDX), and X-ray diffraction (XRD). On using this composite coating as electrodes it was found that the highest electrocatalytic activity was achieved in presence of [H{sub 2}SO{sub 4} (2 g/l) + FeSO{sub 4} (20 mg/l)]. In presence of each of NaOH and H{sub 2}SO{sub 4} the activity of the electrode was poor. The electro-Fenton's reagent was the most suitable oxidizing agent for the oxidation of phenol. The reaction between hydrogen peroxide, produced at a cathode, with ferrous sulphate produces hydroxyl radical, one of the strongest inorganic oxidants. In the presence of organic compound, the hydroxyl radical oxidizes the degradable compound to a free radicals and water. Further chain oxidation of the organic radicals leads to a total decomposition of the organic compound, leaving only carbon dioxide and water. Optimizing the conditions that ensure effective electrochemical degradation of phenol on Ni-Al{sub 2}O{sub 3} composite-coating electrodes necessitates the control of all the operating factors.

  9. Segmental Body Composition Assessment for Obese Japanese Adults by Single-Frequency Bioelectrical Impedance Analysis with 8-point Contact Electrodes

    OpenAIRE

    Sato, Susumu; Demura, Shinichi; Kitabayashi, Tamotsu; Noguchi, Takanori

    2007-01-01

    This study aimed to determine the accuracy of segmental body composition variables estimated by singlefrequency BIA with 8-point contact electrodes (SF-BIA8), compared with dual-energy X-ray absorptiometry (DXA). Subjects were 72 obese Japanese adults (43 males and 29 females) aged 30 to 66 years. Segmental body composition variables (fat free mass : FFM, fat mass : FM, and percent fat mass : %FAT) were measured by these techniques. The correlations between impedance values and FFM measured b...

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

    Science.gov (United States)

    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. Highly crystalline graphene/carbon black composite counter electrodes with controllable content: Synthesis, characterization and application in dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Highlights: ► Certain graphene in composite counter electrode (CE) boosted the efficiency of DSSCs. ► Composite CE combined the merits of graphene and carbon black. ► Systematic research showed the importance of the amount of graphene in composite CE. ► Composite counter electrode had excellent electrochemical stability. -- Abstract: Highly crystalline graphene/carbon black composite counter electrodes, possessing advantages of both rapid electron transport of graphene and high surface area of carbon black, have been prepared using a facile approach. Tuning composite content allows for the fabrication of high-efficiency dye-sensitized solar cells (DSSCs) in this work. The ratio of graphene and carbon black at ca. 1:3 in weight has been confirmed optimum for synthesizing the composite counter electrode. By comparison with those made of either highly crystalline graphene or carbon black, the DSSC based on composite counter electrode has higher conversion efficiency. Moreover, not only does our DSSCs have comparable performance to that of the Pt-based DSSC, but is more cost-effective. Additionally, the chemical catalysis and stability of composite counter electrodes toward I3− reduction, and the interfacial charge transfer have been quantitatively investigated by cyclic voltammetry and electrochemical impedance spectra. The results have revealed that the content of graphene and carbon black in composite counter electrodes is very important for fabricating the DSSCs with high catalytic performance and fast interfacial electron transfer

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

    Science.gov (United States)

    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...

  13. Voltammetry of Lead Cations on a New Type of Silver Composite Electrode in the Presence of Other Cations

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Šebková, Světlana; Kopanica, M.

    2004-01-01

    Roč. 379, - (2004), s. 294-301. ISSN 1618-2642 Grant ostatní: GIT(AR) 101/02/U111/CZ Institutional research plan: CEZ:AV0Z4040901 Keywords : voltammetry * silver composite electrode * lead cations Subject RIV: CG - Electrochemistry Impact factor: 2.098, year: 2004

  14. Electrochemical behaviour of graphene–poly (3,4-ethylene- dioxythiophene) (PEDOT) composite electrodes for supercapacitor applications

    Indian Academy of Sciences (India)

    Dona Jacob; P A Mini; Avinash Balakrishnan; S V Nair; K R V Subramanian

    2014-02-01

    In this paper, we report on the electrochemical characteristics of graphene–PEDOT composite electrodes. The electrodes were made of indium tin oxide (ITO) substrates by simple processes of electrophoretic deposition of graphene followed by electropolymerization of EDOT monomer. The composite electrode was obtained by electrochemical measurements, a median specific capacitance of 1410 F/g and a median area capacitance of 199 mF cm−2 at a scan rate of 40 mVs−1. The composite showed good stability characteristics after repeated scans in cyclic voltammmetry and fared much better than a thin film of PEDOT. The thermal stability of the composite is also much superior when compared to the polymer with a weight loss temperature of 350° C for the composite and 250° C for the polymer, respectively. The above electrochemical and thermal behaviours of the composite are correlated to the unique morphology of electrodeposited graphene that provides a conductive and high surface area template for electropolymerization.

  15. Mathematical Modeling of an Active-Fiber Composite Energy Harvester with Interdigitated Electrodes

    Directory of Open Access Journals (Sweden)

    A. Jemai

    2014-01-01

    Full Text Available The use of active-fiber composites (AFC instead of traditional ceramic piezoelectric materials is motivated by flexibility and relatively high actuation capacity. Nevertheless, their energy harvesting capabilities remain low. As a first step toward the enhancement of AFC’s performances, a mathematical model that accurately simulates the dynamic behavior of the AFC is proposed. In fact, most of the modeling approaches found in the literature for AFC are based on finite element methods. In this work, we use homogenization techniques to mathematically describe piezoelectric properties taking into consideration the composite structure of the AFC. We model the interdigitated electrodes as a series of capacitances and current sources linked in parallel; then we integrate these properties into the structural model of the AFC. The proposed model is incorporated into a vibration based energy harvesting system consisting of a cantilever beam on top of which an AFC patch is attached. Finally, analytical solutions of the dynamic behavior and the harvested voltage are proposed and validated with finite element simulations.

  16. Coulometric titration studies of nonstoichiometric nanocrystalline ceria

    International Nuclear Information System (INIS)

    Oxygen nonstoichiometry measurements in nanocrystalline ceria, x in CeO2-x, were performed using coulometric titration. The measurements reveal large apparent deviations from stoichiometry, of the order of 10-3--10-4 at T = 405--455 C and PO2 = 0.21--10-5 atm, as compared to levels of ∼ 10-9 for coarsened materials under the same conditions. The level of nonstoichiometry is, however, larger then expected from previous electrical conductivity data of nanocrystalline ceria. In addition, x ∝ PO2-1/2 while σ ∝ PO2-1/6. The observed dependence of X(PO2, T) can be explained by either the formation of neutral oxygen vacancies at or near the interface, or by surface adsorption

  17. Effect of poly(3,4-ethylenedioxythiophene) (PEDOT) in carbon-based composite electrodes for electrochemical supercapacitors

    Science.gov (United States)

    Lei, Chunhong; Wilson, Peter; Lekakou, Constantina

    Electrochemical double layer supercapacitor cells were fabricated and tested using composite electrodes of activated carbon with carbon black and poly(3,4-ethylenedioxythiophene) (PEDOT), and an organic electrolyte 1 M TEABF 4/PC solution. The effect of PEDOT on the performance of the EDLC cells was explored and the cells were characterised by electrochemical impedance spectroscopy (EIS), cyclic voltammetry and galvanostatic charge-discharge. A generalised equivalent circuit model was developed for which numerical simulations were performed to determine the properties and parameters of its components from the EIS data. It was found that the proposed model fitted successfully the data of all tested cells. PEDOT enhanced the electrode and cell capacitance via its pseudo-capacitance effect up to a maximum value for an optimum PEDOT loading and greatly increased the energy density of the cell while the maximum power density has been still maintained at supercapacitor levels. Furthermore, PEDOT replaced PVDF as a binder and harmful solvent release was reduced during electrode processing. Activated carbon-carbon black composite electrodes with PEDOT as binder were found to have specific capacitance superior to that of activated carbon-carbon black electrodes with PVDF binder.

  18. Sub-nA spatially resolved conductivity profiling of surface and interface defects in ceria films

    Directory of Open Access Journals (Sweden)

    Tim Farrow

    2015-03-01

    Full Text Available Spatial variability of conductivity in ceria is explored using scanning probe microscopy with galvanostatic control. Ionically blocking electrodes are used to probe the conductivity under opposite polarities to reveal possible differences in the defect structure across a thin film of CeO2. Data suggest the existence of a large spatial inhomogeneity that could give rise to constant phase elements during standard electrochemical characterization, potentially affecting the overall conductivity of films on the macroscale. The approach discussed here can also be utilized for other mixed ionic electronic conductor systems including memristors and electroresistors, as well as physical systems such as ferroelectric tunneling barriers.

  19. Sub-nA spatially resolved conductivity profiling of surface and interface defects in ceria films

    International Nuclear Information System (INIS)

    Spatial variability of conductivity in ceria is explored using scanning probe microscopy with galvanostatic control. Ionically blocking electrodes are used to probe the conductivity under opposite polarities to reveal possible differences in the defect structure across a thin film of CeO2. Data suggest the existence of a large spatial inhomogeneity that could give rise to constant phase elements during standard electrochemical characterization, potentially affecting the overall conductivity of films on the macroscale. The approach discussed here can also be utilized for other mixed ionic electronic conductor systems including memristors and electroresistors, as well as physical systems such as ferroelectric tunneling barriers

  20. Sub-nA spatially resolved conductivity profiling of surface and interface defects in ceria films

    Energy Technology Data Exchange (ETDEWEB)

    Farrow, Tim; Kumar, Amit, E-mail: a.kumar@qub.ac.uk [Centre for Nanostructured Media, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN (United Kingdom); Yang, Nan [CNR-SPIN and Engineering Faculty, Università degli studi Niccolò Cusano, Rome I-00166 (Italy); Doria, Sandra; Balestrino, Giuseppe [CNR-SPIN and DICCI Dipartiment, Università di Roma Tor Vergata, Via del Politecnico 1, I-00133 Rome (Italy); Belianinov, Alex; Jesse, Stephen; Kalinin, Sergei V. [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Arruda, Thomas M. [Chemistry Department, Salve Regina University, Newport, Rhode Island 02840 (United States)

    2015-03-01

    Spatial variability of conductivity in ceria is explored using scanning probe microscopy with galvanostatic control. Ionically blocking electrodes are used to probe the conductivity under opposite polarities to reveal possible differences in the defect structure across a thin film of CeO{sub 2}. Data suggest the existence of a large spatial inhomogeneity that could give rise to constant phase elements during standard electrochemical characterization, potentially affecting the overall conductivity of films on the macroscale. The approach discussed here can also be utilized for other mixed ionic electronic conductor systems including memristors and electroresistors, as well as physical systems such as ferroelectric tunneling barriers.

  1. Modification of glassy carbon electrode with a polymer/mediator composite and its application for the electrochemical detection of iodate

    International Nuclear Information System (INIS)

    Highlights: ► FAD and PEDOT are combined to modify the glassy carbon electrode for IO3− sensing. ► The doping of FAD into PEDOT matrix can almost be viewed as an irreversible process. ► The optimal cycle number for preparing the GCE/PEDOT/FAD electrode is found to be 9. ► The detection limit of the GCE/PEDOT/FAD electrode for IO3− is found to be 0.16 μM. ► The GCE/PEDOT/FAD electrode possesses enough selectivity toward IO3−. - Abstract: A modified glassy carbon electrode was prepared by depositing a composite of polymer and mediator on a glassy carbon electrode (GCE). The mediator, flavin adenine dinucleotide (FAD) and the polymer, poly(3,4-ethylenedioxythiophene) (PEDOT) were electrochemically deposited as a composite on the GCE by applying cyclic voltammetry (CV). This modified electrode is hereafter designated as GCE/PEDOT/FAD. FAD was found to significantly enhance the growth of PEDOT. Electrochemical quartz crystal microbalance (EQCM) analysis was performed to study the mass changes in the electrode during the electrodeposition of PEDOT, with and without the addition of FAD. The optimal cycle number for preparing the modified electrode was determined to be 9, and the corresponding surface coverage of FAD (ΓFAD) was ca. 5.11 × 10−10 mol cm−2. The amperometric detection of iodate was performed in a 100 mM buffer solution (pH 1.5). The GCE/PEDOT/FAD showed a sensitivity of 0.78 μA μM−1 cm−2, a linear range of 4–140 μM, and a limit of detection of 0.16 μM for iodate. The interference effects of 250-fold Na+, Mg2+, Ca2+, Zn2+, Fe2+, Cl−, NO3−, I−, SO42− and SO32−, with reference to the concentration of iodate were negligible. The long-term stability of GCE/PEDOT/FAD was also investigated. The GCE/PEDOT/FAD electrode retained 82% of its initial amperometric response to iodate after 7 days. The GCE/PEDOT/FAD was also applied to determine iodate in a commercial salt.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Liping; Wang, Xianyou; Li, Na; An, Hongfang; Chen, Huajie [School of Chemistry, Key Laboratory of Environmentally Friendly Chemistry and Applications of Minister of Education, Xiangtan University, Hunan 411105 (China); Wang, Ying; Guo, Jia [School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Hubei 430073 (China)

    2010-03-15

    Calcium carbide (CaC{sub 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{sub 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{sup -1} measured by cyclic voltammetry at 1 mV s{sup -1}. Besides, the capacitance retention of coin supercapacitor remained 80.1% after 1000 cycles. (author)

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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. Effect of composition and particle morphology on the electrochemical properties of LaNi{sub 5}-based alloy electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Spodaryk, Mariana, E-mail: poshtamary@ukr.net [Institute for Problems of Materials Science, NAS of Ukraine, 3 Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Shcherbakova, Larisa; Sameljuk, Anatoly [Institute for Problems of Materials Science, NAS of Ukraine, 3 Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Zakaznova-Herzog, Valentina; Braem, Beat; Holzer, Marco; Mauron, Philippe; Remhof, Arndt [Division ‘Hydrogen and Energy’, EMPA Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Solonin, Yurii [Institute for Problems of Materials Science, NAS of Ukraine, 3 Krzhyzhanovsky Str., 03680 Kyiv-142 (Ukraine); Züttel, Andreas [Division ‘Hydrogen and Energy’, EMPA Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf (Switzerland)

    2014-09-01

    Highlights: • Characteristics of Al and Co in substituted gas-atomised alloy electrodes is shown. • Surface composition determines the kinetics and stability of the electrodes. • Corrosion of the Al leads to faster kinetics as compared to the Co-containing alloys. - Abstract: Al and Co substituted LaNi{sub 5}-based intermetallic compounds were investigated as negative electrode materials in alkaline KOH-electrolyte. The structure, morphology and electrochemical properties of gas-atomised and cast LaNi{sub 4.5}Al{sub 0.5} and LaNi{sub 2.5}Co{sub 2.4}Al{sub 0.1} alloys were investigated and the effect of the substitutions and the production method on the surface and bulk composition is compared to cast LaNi{sub 5} as a reference. While the rapid solidification of the gas-atomised alloys affects the site energy distribution for hydrogen on the interstitial sites, the activation and degradation mechanism of the electrodes cycle life is dominated by the elemental composition of the alloy and especially the surface. Therefore, the alloys with the larger Al content activate within a few cycles and also degrade faster as compared to the alloys with a high Co content. Furthermore, the dissolution of Al leads to a highly active surface with a lower reaction resistance, which leads to an order of magnitude increased high rate dischargeability.

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

    Science.gov (United States)

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

    2016-03-01

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

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

    Science.gov (United States)

    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.

  8. Production of Sn–Cu/MWCNT composite electrodes for Li-ion batteries by using electroless tin coating

    Energy Technology Data Exchange (ETDEWEB)

    Uysal, Mehmet, E-mail: mehmetu@sakarya.edu.tr; Cetinkaya, Tugrul; Kartal, Muhammet, E-mail: kartal@sakarya.edu.tr; Alp, Ahmet; Akbulut, Hatem

    2014-12-01

    Cycling stability of pure tin electrodes were aimed to improve by using a suitable combination of copper and multiwalled carbon nanotubes (MWCNTs). For this purpose, firstly Sn–Cu composite powders were produced using an electroless process. Then, Sn–Cu/MWCNT composite electrodes were prepared with dispersing different amounts of MWCNT (10 wt.%, 20 wt.%, 40 wt.%) by high energy mechanical milling method. The surface morphology of the produced Sn–Cu/MWCNT composite powders was characterized using scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) was used to determine the elemental surface composition of the composites. X-ray diffraction (XRD) analysis was performed to investigate the structure of the Sn–Cu/MWCNT composite powders. The electrochemical performance of Sn–Cu/MWCNT composite electrodes has been investigated by charge/discharge tests and cyclic voltammetry experiments. The cell discharge capacities were determined at a constant current in voltage range between 0.02 V and 1.5 V. AC Electrochemical Impedance Spectroscopy (EIS) analysis was also carried out to measure resistivity and Li-diffusion in the assembled cells. The amounts of MWCNTs were shown to be a crucial factor to improve Sn–Cu/MWCNT composite anodes for cyclability and reversible capacity. - Highlights: • Sn–Cu/MWCNT anodes were produced by high energy mechanical milling and electroless method. • MWCNT increases electronic contact between current collector and active material. • The discharge capacity of Sn–Cu/40MWCNT composite was found to be 439 mAh g{sup −1} even after 30 cycles.

  9. Synthesis, microstructure and mechanical properties of ceria stabilized tetragonal zirconia prepared by spray drying technique

    International Nuclear Information System (INIS)

    Ceria stabilized zirconia powders with ceria concentration varying from 6 to 16 mol% were synthesized using spray drying technique. Powders were characterized for their particle size distribution and specific surface area. The dense sintered ceramics fabricated using these powders were characterized for their microstructure, crystallite size and phase composition. The flexural strength, fracture toughness and micro-hardness of sintered ceramics were measured. High fracture toughness and flexural strength were obtained for sintered bodies with 12 mol% of CeO2. Flexural strength and fracture toughness were dependent on CeO2 concentration, crystallite size and phase composition of sintered bodies. Correlation of data has indicated that the transformable tetragonal phase is the key factor in controlling the fracture toughness and strength of ceramics. It has been demonstrated that the synthesis method is effective to prepare nanocrystalline tetragonal ceria stabilized zirconia powders with improved mechanical properties. Ce-ZrO2 with 20 wt% alumina was also prepared with flexural strength, 1200 MPa and fracture toughness 9.2 MPa√m. (author)

  10. Synthesis, microstructure and mechanical properties of ceria stabilized tetragonal zirconia prepared by spray drying technique

    Indian Academy of Sciences (India)

    S C Sharma; N M Gokhale; Rajiv Dayal; Ramji Lal

    2002-02-01

    Ceria stabilized zirconia powders with ceria concentration varying from 6 to 16 mol% were synthesized using spray drying technique. Powders were characterized for their particle size distribution and specific surface area. The dense sintered ceramics fabricated using these powders were characterized for their microstructure, crystallite size and phase composition. The flexural strength, fracture toughness and microhardness of sintered ceramics were measured. High fracture toughness and flexural strength were obtained for sintered bodies with 12 mol% of CeO2. Flexural strength and fracture toughness were dependent on CeO2 concentration, crystallite size and phase composition of sintered bodies. Correlation of data has indicated that the transformable tetragonal phase is the key factor in controlling the fracture toughness and strength of ceramics. It has been demonstrated that the synthesis method is effective to prepare nanocrystalline tetragonal ceria stabilized zirconia powders with improved mechanical properties. Ce–ZrO2 with 20 wt% alumina was also prepared with flexural strength, 1200 MPa and fracture toughness, 9.2 MPa √m.

  11. Electrochemical detection of rutin with a carbon ionic liquid electrode modified by Nafion, graphene oxide and ionic liquid composite

    International Nuclear Information System (INIS)

    We report on a carbon ionic liquid electrode modified with a composite made from Nafion, graphene oxide and ionic liquid, and its application to the sensitive determination of rutin. The modified electrode was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. It shows excellent cyclic voltammetric and differential pulse voltammetric performance due to the presence of nanoscale graphene oxide and the ionic liquid, and their interaction. A pair of well-defined redox peaks of rutin appears at pH 3.0, and the reduction peak current is linearly related to its concentration in the range from 0.08 μM to 0.1 mM with a detection limit of 0.016 μM (at 3σ). The modified electrode displays excellent selectivity and good stability, and was successfully applied to the determination of rutin in tablets with good recovery. (author)

  12. Electrochemical sensing of catechol using a glassy carbon electrode modified with a composite made from silver nanoparticles, polydopamine, and graphene

    International Nuclear Information System (INIS)

    We report on the modification of a glassy carbon electrode with a composite consisting of silver nanoparticles (AgNPs), polydopamine, and graphene to give an electrochemical sensor for catechol. The composite was characterized by transmission electron microscopy, and the electrochemical behavior of catechol at the modified electrode was studied by cyclic voltammetry. The electrochemical response is greatly enhanced and thought to result from a combination of beneficial effects including the good conductivity and large surface area of the AgNPs, the high conductivity of graphene, the synergistic effects of the composite, and the increased quantity of catechol that is adsorbed on the surface of the electrode. Differential pulse voltammetric responses are proportional to the concentration of catechol between 0.5 and 240 μM levels of catechol, and the detection limit is 0.1 μM (S/N = 3). The performance of the sensor was evaluated with catechol-spiked water samples, and recoveries range from 96.5 % to 103.1 %. The results indicated that the composite presented here is a promising substrate for use in electrochemical sensing. (author)

  13. Toxicity evaluation of PEDOT/biomolecular composites intended for neural communication electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Asplund, M; Thaning, E; Von Holst, H [Division of Neuronic Engineering, School of Technology and Health, Royal Institute of Technology, SE-14152 Huddinge (Sweden); Lundberg, J [Section for Neuroradiology, R2:02 NKK-lab, Department of Clinical Neuroscience, Karolinska Institutet, Karolinska University Hospital, Solna, SE-171 76, Stockholm (Sweden); Sandberg-Nordqvist, A C [Section of Clinical CNS Research, Department of Clinical Neuroscience, Karolinska Institutet, Karolinska University Hospital, Solna, SE-171 76, Stockholm (Sweden); Kostyszyn, B [Center for Hearing and Communication Research, Department of Clinical Neuroscience, Karolinska Institutet, Karolinska University Hospital, M1:01, SE-171 76 Stockholm (Sweden); Inganaes, O, E-mail: maria.asplund@sth.kth.s [Biomolecular and Organic Electronics, IFM, Linkoeping University, SE-581 83 Linkoeping (Sweden)

    2009-08-15

    Electrodes coated with the conducting polymer poly(3,4-ethylene dioxythiophene) (PEDOT) possess attractive electrochemical properties for stimulation or recording in the nervous system. Biomolecules, added as counter ions in electropolymerization, could further improve the biomaterial properties, eliminating the need for surfactant counter ions in the process. Such PEDOT/biomolecular composites, using heparin or hyaluronic acid, have previously been investigated electrochemically. In the present study, their biocompatibility is evaluated. An agarose overlay assay using L929 fibroblasts, and elution and direct contact tests on human neuroblastoma SH-SY5Y cells are applied to investigate cytotoxicity in vitro. PEDOT:heparin was further evaluated in vivo through polymer-coated implants in rodent cortex. No cytotoxic response was seen to any of the PEDOT materials tested. The examination of cortical tissue exposed to polymer-coated implants showed extensive glial scarring irrespective of implant material (Pt:polymer or Pt). However, quantification of immunological response, through distance measurements from implant site to closest neuron and counting of ED1+ cell density around implant, was comparable to those of platinum controls. These results indicate that PEDOT:heparin surfaces were non-cytotoxic and show no marked difference in immunological response in cortical tissue compared to pure platinum controls.

  14. Azine/hydrogel/nanotube composite-modified electrodes for NADH catalysis and enzyme immobilization

    International Nuclear Information System (INIS)

    The development of new, efficient bioelectrodes is important to the improvement of biosensor and biofuel cell technology. NAD-dependent dehydrogenase enzymes represent a diverse field of oxidoreductase enzymes that can be used to create unique biosensors and biofuel cells, but require electrocatalysts to oxidize NADH in order to harvest the electrons efficiently from fuel oxidation. This study presents a new methodology for the co-immobilization of dehydrogenase enzymes, azine-based NADH electrocatalysts, carbon nanotubes, and polymer hydrogels. The easy “one-pot” mixing and casting procedure is shown to produce electrodes that can electro-oxidize NADH at low potentials. In situ electropolymerization of the azine dyes within the composites is shown to improve NADH sensitivity, but harms enzyme activity. Biosensors and biofuel cells are constructed with a model enzyme, glucose dehydrogenase, to show the application of this system in a glucose biosensor and biofuel cell. Glucose biosensors produced limiting current densities of 400 μA/cm2 and glucose/air-breathing biofuel cells produced power densities slightly greater than 100 μW/cm2.

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhao; Alford, T. L., E-mail: TA@asu.edu [School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287 (United States); Khorasani, Arash Elhami [ON Semiconductor Corp., Phoenix, Arizona 85005 (United States); Theodore, N. D. [CHD-Fab, Freescale Semiconductor Inc., Tempe, Arizona 85224 (United States); Dhar, A. [Intel Corp., 2501 NW 229th Ave, Hillsboro, Oregon 97124 (United States)

    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.

  19. Composition dependence of methanol oxidation activity in nickel–cobalt hydroxides and oxides: an optimization toward highly active electrodes

    International Nuclear Information System (INIS)

    Graphical Abstract: Display Omitted - Abstract: Non-precious metal electrodes, Ni and Co hydroxides and oxides, have been recently found active towards electro-oxidation of methanol in alkaline. In this article, we present a first and complete study on composition dependence of Ni–Co hydroxides and oxides for methanol electro-oxidation. Ni–Co hydroxide electrodes were prepared by co-electrodeposition on stainless steel mesh (SSM). The atomic ratio of Ni/Ni + Co in Ni–Co hydroxides was controlled by adjusting the ratio of precursor concentration. Ni–Co oxide electrodes were further obtained by annealing the Ni–Co hydroxides. The morphology factors of Ni–Co hydroxides and oxides were revealed by measuring double layer capacitance using cyclic voltammetry (CV). Methanol oxidation reaction (MOR) performance of these Ni–Co hydroxides and oxide electrodes was investigated by CV, and electrochemical impedance spectroscopy (EIS) techniques at room temperature (RT, ∼25 °C). It is found that the MOR performance of Ni–Co hydroxides increased with the increase of Ni content, while the performance of Ni–Co oxide electrodes presented a volcano plot. The highest MOR performance, the smallest charge transfer resistance and Tafel slope were found at the atomic composition of 46% Ni. Such an enhancement probably was due to the synergistic effect of co-existing Ni and Co in the spinel structure. In contrast, the electrode with the mixture of Ni oxide and Co oxide was unable to reach such a high activity. The function of Ni in Ni–Co hydroxides and oxides was attributed to facilitating the methanol oxidation, and in low potential it presented high absorption of intermediate products

  20. Copper-ceria interaction: A combined photoemission and DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Szabová, Lucie, E-mail: szabovalucie@gmail.com [Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8 (Czech Republic); Skála, Tomáš [Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8 (Czech Republic); Sincrotrone Trieste, Strada Statale 14, km 163.5, 34149 Basovizza, Trieste (Italy); Matolínová, Iva [Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8 (Czech Republic); Fabris, Stefano; Farnesi Camellone, Matteo [CNR DEMOCRITOS, Theory@Elettra group, Istituto Officina Molecolare IOM, Area Science Park, 34149 Basovizza, Trieste (Italy); SISSA – Scuola Internazionale Superiore di Studi Avanzati, via Bonomea 265, 34136 Trieste (Italy); Matolín, Vladimír [Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 18000 Prague 8 (Czech Republic)

    2013-02-15

    Stoichiometric and partially reduced ceria films were deposited on preoxidized Ru(0 0 0 1) crystal by Ce evaporation in oxygen atmosphere of different pressures at 700 K. Copper-ceria interaction was investigated by deposition of metalic copper on both types of substrate. The samples were characterized by low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) of core states and resonant photoelectron spectroscopy (RPES) of the valence bands. Copper adsorption on stoichiometric ceria caused reduction of CeO{sub 2}, while on the oxygen-defficient ceria it partially reoxidized the substrate. This is in agreement with DFT+U calculations of copper adsorption on stoichiometric and defective ceria surfaces.

  1. Evaluation of contact resistance between carbon fiber/epoxy composite laminate and printed silver electrode for damage monitoring

    International Nuclear Information System (INIS)

    An addressable conducting network (ACN) makes it possible to monitor the condition of a structure using the electrical resistance between electrodes on the surface of a carbon fiber reinforced plastics (CFRP) structure. To improve the damage detection reliability of the ACN, the contact resistances between the electrodes and CFRP laminates needs to be minimized. In this study, silver nanoparticle electrodes were fabricated via printed electronics techniques on a CFRP composite. The contact resistance between the silver electrodes and CFRP were measured with respect to various fabrication conditions such as the sintering temperature of the silver nano-ink and the surface roughness of the CFRP laminates. The interfaces between the silver electrode and carbon fibers were observed using a scanning electron microscope (SEM). Based on this study, it was found that the lowest contact resistance of 0.3664Ω could be achieved when the sintering temperature of the silver nano-ink and surface roughness were 120 degree C and 0.230 a, respectively.

  2. Evaluation of contact resistance between carbon fiber/epoxy composite laminate and printed silver electrode for damage monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Eun Beom; Kim, Hak Sung [Dept. of Mechanical Convergence Engineering, Hanyang University, Seoul (Korea, Republic of); Takahashi, Kosuke [Dept. of Mechanical Sciences and Engineering, Tokyo Institute of Technology, Tokyo (Korea, Republic of)

    2014-10-15

    An addressable conducting network (ACN) makes it possible to monitor the condition of a structure using the electrical resistance between electrodes on the surface of a carbon fiber reinforced plastics (CFRP) structure. To improve the damage detection reliability of the ACN, the contact resistances between the electrodes and CFRP laminates needs to be minimized. In this study, silver nanoparticle electrodes were fabricated via printed electronics techniques on a CFRP composite. The contact resistance between the silver electrodes and CFRP were measured with respect to various fabrication conditions such as the sintering temperature of the silver nano-ink and the surface roughness of the CFRP laminates. The interfaces between the silver electrode and carbon fibers were observed using a scanning electron microscope (SEM). Based on this study, it was found that the lowest contact resistance of 0.3664Ω could be achieved when the sintering temperature of the silver nano-ink and surface roughness were 120 degree C and 0.230 a, respectively.

  3. Long Term Stability Investigation of Solid Oxide Electrolysis Cell with Infiltrated Porous YSZ Air Electrode Under High Current

    DEFF Research Database (Denmark)

    Veltzé, Sune; Ovtar, Simona; Simonsen, Søren Bredmose; Thydén, Karl Tor Sune; Kiebach, Wolff-Ragnar; Küngas, Rainer

    stabilised zirconia (YSZ) backbone air electrode and Ni/YSZ cermet fuel electrode. The SOC was tested at electrolysis conditions under high current (up to -1 A/cm2). The porous YSZ electrodes was infiltrated with gadolinium-doped ceria oxide (CGO), to act as a barrier layer between the catalyst and the...

  4. Effect of Elemental Composition on the Structure, Electrochemical Properties, and Ozone Production Activity of Ti/SnO2-Sb-Ni Electrodes Prepared by Thermal Pyrolysis Method

    OpenAIRE

    Mohammad K. Amini; Hamed Shekarchizade

    2011-01-01

    Ti/SnO2-Sb-Ni electrodes with various Ni- and Sb-doping levels have been prepared by dip-coating thermal pyrolysis procedure, and their simultaneous electrochemical ozone production (EOP) and oxygen evolution reaction (OER) were investigated. The effects of electrode composition on the nanostructure, morphology, electrochemical behavior, kinetic parameters, and lifetime of the electrodes were systematically studied using X-ray diffraction, scanning electron microscopy, cyclic voltammetry, lin...

  5. A Hydrogen Peroxide Biosensor Combined HRP Doped Polypyrrole with Ferrocene Modified Sol-gel Derived Composite Carbon Electrode

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A novel amperometric biosensor for the detection of hydrogen peroxide is described.The biosensor was constructed by electrodepositing HRP/PPy membrane on the surface of ferrocenecarboxylic acid mediated sol-gel derived composite carbon electrode. The biosensor gives response to hydrogen peroxide in a few seconds with detection limit of 5×l0-7 mol · L-1(based on signal: noise=3). Linear range is up to 0.2 mmol · L-1.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Relation Between the Composition and Properties of Carbon Ionic Liquid Electrodes (CILEs)

    Czech Academy of Sciences Publication Activity Database

    Mikysek, T.; Stočes, M.; Jovanovski, V.; Sopha, H.; Švancara, I.; Ludvík, Jiří

    Pardubice : University Press Centre, 2011 - (Kalcher, K.; Metelka, R.; Švancara, I.; Vytřas, K.), s. 157-166 ISBN 978-80-7395-434-5 R&D Projects: GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : carbon ionic liquid electrode * carbon paste electrode * characterization Subject RIV: CG - Electrochemistry

  8. Relation between the composition and properties of carbon nanotubes paste electrodes (CNTPEs)

    Czech Academy of Sciences Publication Activity Database

    Mikysek, T.; Stočes, M.; Švancara, I.; Ludvík, Jiří

    Pardubice : Univerzita Pardubice, 2010, s. 69-75. ISBN 978-80-7395-348-5 R&D Projects: GA MŠk(CZ) LC06035; GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : carbon nanotube paste electrode * carbon paste electrode * characterization Subject RIV: CG - Electrochemistry

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

    Science.gov (United States)

    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

  10. Detection of dopamine in non-treated urine samples using glassy carbon electrodes modified with PAMAM dendrimer-Pt composites

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M.G. [Laboratory of Bioelectrochemistry, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, S. C., Parque Tecnologico, Queretaro, Sanfandila, Pedro Escobedo 76703, Queretaro (Mexico); Department of Chemistry, Universidad de Guanajuato, Cerro de la Venada S/N Col. Pueblito de Rocha, 36040 Guanajuato, Gto (Mexico); Armendariz, G.M.E.; Godinez, Luis A.; Torres, J. [Laboratory of Bioelectrochemistry, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, S. C., Parque Tecnologico, Queretaro, Sanfandila, Pedro Escobedo 76703, Queretaro (Mexico); Sepulveda-Guzman, S. [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Universidad, San Nicolas de los Garza, Nuevo Leon, 66451 Nuevo Leon (Mexico); Bustos, E., E-mail: ebustos@cideteq.mx [Laboratory of Bioelectrochemistry, Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, S. C., Parque Tecnologico, Queretaro, Sanfandila, Pedro Escobedo 76703, Queretaro (Mexico)

    2011-09-01

    Composites of hydroxyl-terminated PAMAM dendrimers, generation 4.0 (64 peripheral OH groups) containing Pt nanoparticles were synthesized at different reaction times using a microwave reactor. The synthetic procedure resulted in dendrimer encapsulated nanoparticles of Pt (DENs-Pt) of 1.53 {+-} 0.17 nm diameter that was calculated from transmission electron microscopy, and the Pt nanoparticles had single crystal plane in (1 1 1) orientation determinate by selective area diffraction. Each composite was electrochemically immobilized on a pre-functionalized glassy carbon (GC) electrode that was incorporated as a flow injection amperometric (FIA) detector, for the selective detection and quantification of dopamine (DA) in untreated urine samples. Comparison of the analytical performance of the novel electrochemical detector revealed that the DENs-Pt modified GC electrode with the composite synthesized for 30 min in the microwave reactor, showed the best response for the detection of DA in samples of non-treated urine, being the detection and quantification limits smaller (19 and 9 ppb, respectively) than those corresponding to the naked a GC electrode (846 and 423 ppb, respectively) using the FIA detector. In addition, it was found that this electroanalytical approach suffers minimal matrix effects that arise in the analysis of DA in untreated samples of urine.

  11. Influence of calcium and lithium on the densification and electrical conductivity of gadolinia-doped ceria

    International Nuclear Information System (INIS)

    In this work, the use of calcium and lithium as sintering aid to gadolinia-doped ceria was systematically investigated. The main purpose was to verify the influence of these additives on the densification and electrical conductivity of sintered ceramics. Powder compositions containing up to 1.5 mol% (metal basis) of calcium or lithium were prepared by both solid state reaction and oxalate coprecipitation methods. The main characterization techniques were thermal analyses, X-ray diffraction, scanning electron microscopy and electrical conductivity by impedance spectroscopy. Both additives promoted densification of gadolinia-doped ceria. The densification increases with increasing the additive content. Different effects on microstructure and electrical conductivity result from the method of preparation, e.g., solid state reaction or coprecipitation. Calcium addition greatly enhances the grain growth compared to lithium addition. The electrical conductivity of specimens containing a second additive is lower than that of pure gadolinia-doped ceria. Both additives influence the intergranular conductivity and favor the exudation of gadolinium out of the solid solution. (author)

  12. Facile preparation of free-standing rGO paper-based Ni-Mn LDH/graphene superlattice composites as a pseudocapacitive electrode.

    Science.gov (United States)

    Quan, W; Tang, Z L; Wang, S T; Hong, Y; Zhang, Z T

    2016-02-23

    A novel film electrode was assembled via a simple filtration process, with an rGO paper as the substrate and Ni-Mn LDH/graphene superlattice composites as the functional layer. The electrode presented typical pseudocapacitive behaviours with excellent rate property and cycle stability. PMID:26856730

  13. Carbon Deposition during CO2 Electrolysis in Ni-Based Solid-Oxide-Cell Electrodes

    DEFF Research Database (Denmark)

    Skafte, Theis Løye; Graves, Christopher R.; Blennow, P.;

    2015-01-01

    The carbon formation threshold in an operating cell was investigated during electrolysis of an idealized reactant atmosphere of CO and CO2. The electrolysis current was gradually increased in steps until the cell voltage spontaneously increased, thereby indicating cell degradation and possibly the...... onset of carbon deposition. The outlet gas composition at each current step was estimated based on the inlet gas composition and the reactant conversion using Faraday's law. The increase in voltage was observed at lower outlet pCO/pCO2 ratios than that corresponding to the expected thermodynamic...... threshold for carbon formation. The degradation observed was related to the fuel electrode, as confirmed by electrochemical impedance spectroscopy. Mitigation of the degradation mechanism was attempted by infiltrating gadolinium doped ceria. The onset of carbon deposition was largely unaffected, but the...

  14. A novel electrochemical sensor of bisphenol A based on stacked graphene nanofibers/gold nanoparticles composite modified glassy carbon electrode

    International Nuclear Information System (INIS)

    In this paper, a novel and convenient electrochemical sensor based on stacked graphene nanofibers (SGNF) and gold nanoparticles (AuNPs) composite modified glassy carbon electrode (GCE) was developed for the determination of bisphenol A (BPA). The AuNPs/SGNF modified electrode showed an efficient electrocatalytic role for the oxidation of BPA, and the oxidation overpotentials of BPA were decreased significantly and the peak current increased greatly compared with bare GCE and other modified electrode. The transfer electron number (n) and the charge transfer coefficient (α) were calculated with the result as n = 4, α = 0.52 for BPA, which indicated the electrochemical oxidation of BPA on AuNPs/SGNF modified electrode was a four-electron and four-proton process. The effective surface areas of AuNPs/SGNF/GCE increased for about 1.7-fold larger than that of the bare GCE. In addition, the kinetic parameters of the modified electrode were calculated and the apparent heterogeneous electron transfer rate constant (ks) was 0.51 s−1. Linear sweep voltammetry was applied as a sensitive analytical method for the determination of BPA and a good linear relationship between the peak current and BPA concentration was obtained in the range from 0.08 to 250 μM with a detection limit of 3.5 × 10−8 M. The modified electrode exhibited a high sensitivity, long-term stability and remarkable reproducible analytical performance and was successfully applied for the determination of BPA in baby bottles with satisfying results

  15. Mechanistic studies of water electrolysis and hydrogen electro-oxidation on high temperature ceria-based solid oxide electrochemical cells.

    Science.gov (United States)

    Zhang, Chunjuan; Yu, Yi; Grass, Michael E; Dejoie, Catherine; Ding, Wuchen; Gaskell, Karen; Jabeen, Naila; Hong, Young Pyo; Shavorskiy, Andrey; Bluhm, Hendrik; Li, Wei-Xue; Jackson, Gregory S; Hussain, Zahid; Liu, Zhi; Eichhorn, Bryan W

    2013-08-01

    Through the use of ambient pressure X-ray photoelectron spectroscopy (APXPS) and a single-sided solid oxide electrochemical cell (SOC), we have studied the mechanism of electrocatalytic splitting of water (H2O + 2e(-) → H2 + O(2-)) and electro-oxidation of hydrogen (H2 + O(2-) → H2O + 2e(-)) at ∼700 °C in 0.5 Torr of H2/H2O on ceria (CeO2-x) electrodes. The experiments reveal a transient build-up of surface intermediates (OH(-) and Ce(3+)) and show the separation of charge at the gas-solid interface exclusively in the electrochemically active region of the SOC. During water electrolysis on ceria, the increase in surface potentials of the adsorbed OH(-) and incorporated O(2-) differ by 0.25 eV in the active regions. For hydrogen electro-oxidation on ceria, the surface concentrations of OH(-) and O(2-) shift significantly from their equilibrium values. These data suggest that the same charge transfer step (H2O + Ce(3+) Ce(4+) + OH(-) + H(•)) is rate limiting in both the forward (water electrolysis) and reverse (H2 electro-oxidation) reactions. This separation of potentials reflects an induced surface dipole layer on the ceria surface and represents the effective electrochemical double layer at a gas-solid interface. The in situ XPS data and DFT calculations show that the chemical origin of the OH(-)/O(2-) potential separation resides in the reduced polarization of the Ce-OH bond due to the increase of Ce(3+) on the electrode surface. These results provide a graphical illustration of the electrochemically driven surface charge transfer processes under relevant and nonultrahigh vacuum conditions. PMID:23822749

  16. A novel nonenzymatic hydrogen peroxide sensor based on silver nanoparticles and ionic liquid functionalized multiwalled carbon nanotube composite modified electrode

    International Nuclear Information System (INIS)

    Highlights: • A novel nonenzymatic H2O2 sensor was constructed on AgNPs/MWCNTs-IL modified GCE. • Ionic liquid functionalized carbon nanotube was used as matrices for deposition of AgNPs effectively. • AgNPs were uniformly and less agglomerate formed on the MWCNTs-IL film. • AgNPs/MWCNTs-IL/GCE displayed good electrocatalytic activity to the reduction of H2O2 and applied to real samples. • The electrocatalytic mechanism of the constructed sensor was proposed. -- Abstract: A novel hydrogen peroxide (H2O2) sensor was fabricated by electrodepositing Ag nanoparticles (NPs) on a glassy carbon electrode (GCE) modified with ionic liquid functionalized multiwalled carbon nanotube (MWCNTs-IL) composites. The AgNPs/MWCNTs-IL composite was characterized by different methods including scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The constructed electrode exhibited good catalytic activity toward the reduction of H2O2, and obtained a linear response to logarithm of the H2O2 concentrations ranging from 1.2 × 10−8 to 4.8 × 10−6 M with a limit of detection (LOD) of 3.9 × 10−9 M. Moreover, it can be applied to real samples analysis. The excellent performance of hydrogen peroxide sensor were ascribed to the MWCNTs-IL composites being used as effective load matrix for the deposition of AgNPs and the synergistic amplification effect of the two kinds of nanomaterials – AgNPs and MWCNTs. Therefore, the catalytic mechanism of the constructed sensor was proposed. AgNPs dispersed on MWCNTs-IL were used as the catalyst for the H2O2 into O2, and the generated oxygen transported the electrode surrounding where it was detected by reduction on the electrode

  17. Ceria concentration effect on chemical mechanical polishing of optical glass

    International Nuclear Information System (INIS)

    It was found material removal rate (MRR) sharply increased from 250 to 675 nm/min as the concentration decreased from 1 to 0.25 wt% in optical glass chemical mechanical polishing (CMP) using ceria slurries. Scanning electron microscopy was employed to characterize the ceria abrasive used in the slurry. Atomic force microscopy results showed good surface had been got after CMP. Schematic diagrams of the CMP process were shown. Furthermore, the absorption spectra indicated a sudden change from Ce4+ to Ce3+ of the ceria surface when the concentration decreased, which revealed a quantum origin of the phenomenon

  18. Characterization of ceria-based SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Doshi, R.; Routbort, J.; Krumpelt, M. [Argonne National Lab., IL (United States)

    1996-12-31

    Solid Oxide Fuel Cells (SOFCs) operating at low temperatures (500-700{degrees}C) offer many advantages over the conventional zirconia-based fuel cells operating at higher temperatures. Reduced operating temperatures result in: (1) Application of metallic interconnects with reduced oxidation problems (2) Reduced time for start-up and lower energy consumption to reach operating temperatures (3) Increased thermal cycle ability for the cell structure due to lower thermal stresses of expansion mismatches. While this type of fuel cell may be applied to stationary applications, mobile applications require the ability for rapid start-up and frequent thermal cycling. Ceria-based fuel cells are currently being developed in the U.K. at Imperial College, Netherlands at ECN, and U.S.A. at Ceramatec. The cells in each case are made from a doped ceria electrolyte and a La{sub 1-x}Sr{sub x}Co{sub 1-y}Fe{sub y}O{sub 3} cathode.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Won-Yong Jeon

    2015-12-01

    Full Text Available 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(OH2/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.

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

    Science.gov (United States)

    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

  3. Performance of the Chemical and Electrochemical Composites of PPy/CNT as Electrodes in Type I Supercapacitors

    Directory of Open Access Journals (Sweden)

    S. C. Canobre

    2015-01-01

    Full Text Available Polypyrrole (PPy is one of the most studied conducting polymers and a very promising material for various applications such as lithium-ion secondary batteries, light-emitting devices, capacitors, and supercapacitors, owing to its many advantages, including good processability, easy handling, and high electronic conductivity. In this work, PPy films were chemically and electrochemically synthesized, both in and around carbon nanotubes (CNTs. The cyclic voltammograms of the device, composed of the electrochemically synthesized PPy/CNT composites as working and counter electrodes (Type I supercapacitor with p-type doping, showed a predominantly capacitive profile with low impedance values and good electrochemical stability, with the anodic charge remaining almost constant (11.38 mC, a specific capacitance value of 530 F g−1 after 50 charge and discharge cycles, and a coulombic efficiency of 99.2%. The electrochemically synthesized PPy/CNT composite exhibited better electrochemical properties compared to those obtained for the chemically synthesized composite. Thus, the electrochemically synthesized PPy/CNT composite is a promising material to be used as electrodes in Type I supercapacitors.

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

    Science.gov (United States)

    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

  5. Nickel Sulfide/Graphene/Carbon Nanotube Composites as Electrode Material for the Supercapacitor Application in the Sea Flashing Signal System

    Institute of Scientific and Technical Information of China (English)

    Hailong Chen; Ji Li; Conglai Long; Tong Wei; Guoqing Ning; Jun Yan; Zhuangjun Fan

    2014-01-01

    This work presents NiS/graphene/carbon nanotube (NiS/GNS/CNT) composites as electrode material for the supercapacitor application in sea flashing signal systems. NiS nanosheets were closely anchored on the conductive GNS-CNT networks. As a result, the NiS/GNS/CNT electrode showed a high specific capacitance of 2 377 F·g-1 at 2 mV·s-1 and good cycling stability compared with the pure NiS (1 599 F·g-1 ). The enhanced electrochemical performances are attributed to the synergetic effect between the conductive carbon and the pseudo-capacitive NiS. The high performance supercapacitor may provide application in the sea flashing signal system.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Van Hoa [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 712-749 (Korea, Republic of); Department of Chemistry, Nha Trang University, 2 Nguyen Dinh Chieu, Nha Trang (Viet Nam); Tran, Trung Hieu [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 712-749 (Korea, Republic of); Shim, Jae-Jin, E-mail: jjshim@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 712-749 (Korea, Republic of)

    2014-11-01

    Conducting poly(o-phenylenediamine) (POPD)/graphene oxide (GO) composites were prepared using a facile and efficient method involving the in-situ polymerization of OPD in the presence of GO in an aqueous medium. Copper sulfate was used as an oxidative initiator for the polymerization of OPD. Scanning electron microscopy and transmission electron microscopy images showed that POPD microfibrils were formed and distributed relatively uniformly with GO sheets in the obtained composites. X-ray diffraction results revealed the highly crystal structure of POPD. This composite exhibited good catalytic activity and stability. These results highlight the potential applications of POPD/GO composites as excellent electrochemical sensors. The composites were used to modify glass carbon electrodes for the chemical detection of hydrogen peroxide in aqueous media. - Highlights: • Graphene oxide/poly(o-phenylenediamine) composites were prepared efficiently. • POPD microfibrils were distributed relatively uniformly with GO sheets. • The composite exhibited good catalytic activity and stability for H{sub 2}O{sub 2} sensing.

  9. Ozonation of bezafibrate over ceria and ceria supported on carbon materials.

    Science.gov (United States)

    Gonçalves, Alexandra G; Órfão, José J M; Pereira, Manuel Fernando R

    2015-01-01

    Two catalysts containing ceria dispersed on the surface of multi-walled carbon nanotubes and activated carbon were investigated as ozonation catalysts for the mineralization of bezafibrate (BZF). The results were compared with those obtained in the absence of the catalyst and in the presence of the parent carbon materials, as well as in the presence of ceria (CeO2). Carbon materials containing ceria showed an interesting catalytic effect. Both materials enhanced the mineralization of BZF relatively to single ozonation and ozonation catalysed by the corresponding carbon materials. In the catalytic ozonation with these materials, both surface and bulk reactions are supposed to occur. The BZF ozonation catalysed by CeO2 leaded to the highest mineralization degrees, indicating that the reaction mechanism followed in the presence of CeO2 (free radical oxidation in solution) leads to the formation of intermediates more easily degradable, mainly after 120 min of reaction. Some primary products and refractory final oxidation compounds in single and catalytic ozonation of BZF were followed. The original chlorine present on the BZF molecule is completely converted to chloride anion and part of the nitrogen is mainly converted to NO3- along with smaller amounts of NO2- and NH4+. Microtox tests revealed that simultaneous use of ozone and CeO2 originated lower acute toxicity. PMID:25189707

  10. Fabrication of lithium titanate/graphene composites with high rate capability as electrode materials for hybrid electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Rong, E-mail: xuerongsmile@qq.com; Yan, Jingwang, E-mail: yanjw@dicp.ac.cn; Jiang, Liang, E-mail: jiangliang@dicp.ac.cn; Yi, Baolian, E-mail: blyi@dicp.ac.cn

    2015-06-15

    A lithium titanate (Li{sub 4}Ti{sub 5}O{sub 12})/graphene composite (LTO/graphene) is fabricated with a one-pot sol–gel method. Graphite oxide is dispersed in an aqueous solution of lithium acetate and tetrabutyl titanate followed by heat treatment in H{sub 2}/Ar. The LTO/graphene composite with reduced aggregation and improved homogeneity is investigated as an anode material for electrochemical capacitors. Electron transport is improved by the conductive graphene network in the insulating Li{sub 4}Ti{sub 5}O{sub 12} particles. The charge transfer resistance at the particle/electrolyte interface is reduced from 83.1 Ω to 55.4 Ω. The specific capacity of LTO/graphene composite is 126 mAh g{sup −1} at 20C. The energy density and power density of a hybrid electrochemical supercapacitor with a LTO/graphene negative electrode and an activated carbon positive electrode are 120.8 Wh kg{sup −1} and 1.5 kW kg{sup −1}, respectively, which is comparable to that of conventional electrochemical double layer capacitors (EDLCs). The LTO/graphene composite fabricated by the one-pot sol–gel method is a promising anode material for hybrid electrochemical supercapacitors. - Highlights: • A Li{sub 4}Ti{sub 5}O{sub 12}/graphene composite was fabricated with a one-pot sol–gel method. • The Li{sub 4}Ti{sub 5}O{sub 12}/graphene composite showed a reduced aggregation and an improved homogeneity. • The Li{sub 4}Ti{sub 5}O{sub 12}/graphene based hybrid supercapacitor exhibited higher energy and power densities.

  11. Fabrication of lithium titanate/graphene composites with high rate capability as electrode materials for hybrid electrochemical supercapacitors

    International Nuclear Information System (INIS)

    A lithium titanate (Li4Ti5O12)/graphene composite (LTO/graphene) is fabricated with a one-pot sol–gel method. Graphite oxide is dispersed in an aqueous solution of lithium acetate and tetrabutyl titanate followed by heat treatment in H2/Ar. The LTO/graphene composite with reduced aggregation and improved homogeneity is investigated as an anode material for electrochemical capacitors. Electron transport is improved by the conductive graphene network in the insulating Li4Ti5O12 particles. The charge transfer resistance at the particle/electrolyte interface is reduced from 83.1 Ω to 55.4 Ω. The specific capacity of LTO/graphene composite is 126 mAh g−1 at 20C. The energy density and power density of a hybrid electrochemical supercapacitor with a LTO/graphene negative electrode and an activated carbon positive electrode are 120.8 Wh kg−1 and 1.5 kW kg−1, respectively, which is comparable to that of conventional electrochemical double layer capacitors (EDLCs). The LTO/graphene composite fabricated by the one-pot sol–gel method is a promising anode material for hybrid electrochemical supercapacitors. - Highlights: • A Li4Ti5O12/graphene composite was fabricated with a one-pot sol–gel method. • The Li4Ti5O12/graphene composite showed a reduced aggregation and an improved homogeneity. • The Li4Ti5O12/graphene based hybrid supercapacitor exhibited higher energy and power densities

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    KAUST Repository

    Almuhammadi, Khaled

    2015-10-19

    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.

  16. Enhanced sensitivity for biosensors: Functionalized P1,5-diaminonaphthalene-multiwall carbon nanotube composite film-modified electrode

    International Nuclear Information System (INIS)

    A homogeneous electroactive poly(1,5-diaminonaphthalene) (P1,5DAN) and multiwalled carbon nanotube (MWNT) composite film-modified electrode was fabricated by cyclic voltammetry and a casting method. The dispersion and morphology of the MWNTs/P1,5DAN composite film were investigated by scanning electron microscopy. The cyclic voltammograms of the electrode modified by the MWNTs/P15DAN composite film strongly depended on the film thickness and pH of the electrolyte solution. Two absolutely isolated oxidation potentials were found as the MWCNTs were immobilized onto the surface of P1,5DAN film in a pH 6.8 buffer solution containing ascorbic acid (AA) and uric acid (UA). Both peak currents linearly increased with increased concentrations. The electrochemical behavior of UA was not interrupted even in the presence of high-concentration AA given that AA had no observable electrochemical changes at the immobilized concentration. The electrocatalytic behavior of H2O2 was also investigated by steady-state amperometry for the immobilization of horseradish peroxidase on the P1,5DAN film. The plot of the response current vs. H2O2 concentration was linear over the wide concentration range of 0.015–5.37 mM.

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

    Science.gov (United States)

    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

  18. Electro-oxidation treatment of Sn/PANI electrode and electrocatalytic activity of Pt/Sn hydroxide/PANI composite electrodes

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hai-hui; PENG Zheng; JIAO Yong-gang; LIAO Jie; KUANG Ya-fei

    2008-01-01

    After being electro-oxidized by cyclic voltammetry(CV) method in 0.5 mol/L H2504 solution or in 0.2mol/L H2O2+0.5 mol/L H2SO4 solution, the Sn/polyaniline (PANI) electrodes were modified with Pt microparticles by pulse galvanostatic method, thus Pt/Sn hydroxide/PANI electrodes were prepared. The electrocatalytic activities of the Pt/Sn/PANI electrode and Pt/Sn hydroxide/PANI electrode for formaldehyde electro-oxidation were investigated by CV method. The effects of deposition charges (Qdep) of PANI, Sn and Pt, scan rate and formaldehyde concentration on the electrocatalytic activity of Pt/Sn hydroxide/PANI electrode were also studied. The results show that the electrocatalytic activities of the Pt/Sn hydroxide/PANI electrodes are much higher than those of the Pt/Sn/PANI electrode.

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

    Science.gov (United States)

    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.

  20. Electrode processes in KCl-KF melt of eutectic composition, containing Gd2O3

    International Nuclear Information System (INIS)

    Electric reduction of gadolinium ions from eutectic melt KCl-KF with gadolinium oxide additions (0.210-1.233 wt. %) at a temperature of 1008 K on molybdenum and glass carbon electrodes was studied. Solubility of gadolinium oxide in the range of temperatures 610-922 deg C was determined. It is shown that reduction of gadolinium oxofluoride complex takes place reversibly with subsequent reversible chemical reaction. Gadolinium reduction on iron electrode in eutectic solution KCl-KF treated for unwanted oxide-ion impurities involves formation of iron-gadolinium alloy

  1. A well-structured metastable ceria surface

    Energy Technology Data Exchange (ETDEWEB)

    Olbrich, R.; Pieper, H. H.; Oelke, R.; Wilkens, H.; Wollschläger, J.; Reichling, M., E-mail: reichling@uos.de [Fachbereich Physik, Universität Osnabrück, Barbarastr. 7, 49076 Osnabrück (Germany); Zoellner, M. H.; Schroeder, T. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany)

    2014-02-24

    By the growth of a 180 nm thick film on Si(111), we produce a metastable ceria surface with a morphology dominated by terraced pyramids with an oriented triangular base. Changes in the nanoscale surface morphology and local surface potential due to annealing at temperatures ranging from 300 K to 1150 K in the ultra-high vacuum are studied with non-contact atomic force microscopy and Kelvin probe force microscopy. As the surface is stable in the temperature range of 300 K to 850 K, it is most interesting for applications requiring regular steps with a height of one O-Ce-O triple layer.

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

    Science.gov (United States)

    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.

  3. Evolution of the chemical bonding nature and electrode activity of indium selenide upon the composite formation with graphene nanosheets

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted -- Highlights: • In4Se2.85@graphene nanocomposite is easily prepared by high energy mechanical milling process. • The bond covalency of In4Se2.85 is notably changed upon the composite formation with graphene. • In4Se2.85@graphene nanocomposite shows promising anode performance for lithium ion battery. -- Abstract: Evolution of the chemical bonding nature and electrochemical activity of indium selenide upon the composite formation with carbon species is systematically investigated. Nanocomposites of In4Se2.85@graphene and In4Se2.85@carbon-black are synthesized via a solid state reaction between In and Se elements, and the following high energy mechanical milling of In4Se2.85 with graphene and carbon-black, respectively. The high energy mechanical milling (HEMM) of In4Se2.85 with carbon species gives rise to a decrease of particle size with a significant depression of the crystallinity of In4Se2.85 phase. In contrast to the composite formation with carbon-black, that with graphene induces a notable decrease of (In−Se) bond covalency, underscoring significant chemical interaction between graphene and In4Se2.85. Both the nanocomposites of In4Se2.85@graphene and In4Se2.85@carbon-black show much better anode performance for lithium ion batteries with larger discharge capacity and better cyclability than does the pristine In4Se2.85 material, indicating the beneficial effect of composite formation on the electrochemical activity of indium selenide. Between the present nanocomposites, the electrode performance of the In4Se2.85@graphene nanocomposite is superior to that of the In4Se2.85@carbon-black nanocomposite, which is attributable to the weakening of (In−Se) bonds upon the composite formation with graphene as well as to the better mixing between In4Se2.85 and graphene. The present study clearly demonstrates that the composite formation with graphene has strong influence on the chemical bonds and electrode activity of indium

  4. Synthesis and characterization of (Ba,Yb doped ceria nanopowders

    Directory of Open Access Journals (Sweden)

    Branko Matović

    2011-06-01

    Full Text Available Nanometric size (Ba, Yb doped ceria powders with fluorite-type structure were obtained by applying selfpropagating room temperature methods. Tailored composition was: Ce0.95−xBa0.05YbxO2−δ with fixed amount of Ba − 0.05 and varying Yb content “x” from 0.05 to 0.2. Powder properties such as crystallite and particle size and lattice parameters have been studied. Röntgen diffraction analyses (XRD were used to characterize the samples at room temperature. Also, high temperature treatment (up to 1550°C was used to follow stability of solid solutions. The mean diameters of the nanocrystals are determined from the full width at half maxima (FWHM of the XRD peaks. It was found that average diameter of crystallites is less than 3 nm. WilliamsonHall plots were used to separate the effect of the size and strain in the nanocrystals.

  5. Electrochemistry of ruthenium dioxide composite electrodes in diethylmethylammonium-triflate protic ionic liquid and its mixtures with acetonitrile

    International Nuclear Information System (INIS)

    Ruthenium dioxide electrodes store charge via faradaic reactions involving proton exchange with the electrolyte, thereby achieving very high specific capacitance values that make it a very interesting material for electrochemical capacitors. We demonstrated earlier that these faradaic reactions occur for RuO2 in non-aqueous electrolytes based on protic ionic liquids, but the specific capacitance were limited due to the high degree of crystallinity of the material prepared in thin films by thermal decomposition. In order to increase the specific capacitance and to evaluate the impact of proton transport and transfer in high load electrodes, RuO2 was prepared by a conventional sol-gel route and used as the active material in a composite electrode to evaluate its electrochemical response in the protic ionic liquid diethymethylammonium-trifluoromethanesulfonate (DEMA-TfO). Cyclic voltammetry was carried out in the pure DEMA-TfO as well as in mixtures of the ionic liquid with acetonitrile. The results showed a significant impact of the electrolyte viscosity and conductivity at high potential scan rates and a limitation of the proton transfer rate at low scan rates. The specific capacitance can be improved at low scan rates by increasing temperature, reaching a value of 338 F/g at 120 °C with a 2 mV/s scan rate. This value is by far the highest reported for RuO2 in a non-aqeuous electrolyte

  6. A red-to-gray poly(3-methylthiophene) electrochromic device using a zinc hexacyanoferrate/PEDOT:PSS composite counter electrode

    International Nuclear Information System (INIS)

    In this paper, we describe a novel red-to-gray poly(3-methylthiophene) (PMeT) electrochromic device (ECD) with the aid of a zinc hexacyanoferrate (ZnHCF)/PEDOT:PSS counter electrode. The application of ZnHCF to an ECD is first reported. ZnHCF has long suffered from poor deposition yield problem, but we demonstrate that a robust ZnHCF film can be prepared by spin coating of a liquid suspension composed of ZnHCF nanoparticles and PEDOT:PSS ink on ITO. It was found that the ZnHCF/PEDOT:PSS composite worked much better with PMeT than pure ZnHCF or pure PEDOT:PSS from both electrochemical and optical aspects. With a LiClO4/PC electrolyte, the PMeT ECD having ZnHCF/PEDOT:PSS as its counter electrode could be reversibly switched between its red state (>0.8 V) and its gray state (2/C. The maximum contrast ratio was 5.45 at 720 nm. In addition, the charge capacity of the ECD could retain 95% of its original value after 10,000 cycles of cyclic voltammetry aging test, although an electrodeposited PMeT film alone could be cycled several hundred times only. To sum up, this work proposes a new, cost-effective transparent counter electrode and brings a stable, high visual-contrast PMeT ECD prototype for further development of a red-color bistable display.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Characterisation of hydrophobic carbon nanofiber-silica composite film electrodes for redox liquid immobilisation

    International Nuclear Information System (INIS)

    Carbon (50-150 nm diameter) nanofibers were embedded into easy to prepare thin films of a hydrophobic sol-gel material and cast onto tin-doped indium oxide substrate electrodes. They promote electron transport and allow efficient electrochemical reactions at solid|liquid and at liquid|liquid interfaces. In order to prevent aggregation of carbon nanofibers silica nanoparticles of 7 nm diameter were added into the sol-gel mixture as a 'surfactant' and homogeneous high surface area films were obtained. Scanning electron microscopy reveals the presence of carbon nanofibers at the electrode surface. The results of voltammetric experiments performed in redox probe-ferrocenedimethanol solution in aqueous electrolyte solution indicate that in the absence of organic phase, incomplete wetting within the hydrophobic film of carbon nanofibers can cause hemispherical diffusion regime typical for ultramicroelectrode like behaviour. The hydrophobic film electrode was modified with two types of redox liquids: pure tert-butylferrocene or dissolved in 2-nitrophenyloctylether as a water-insoluble solvent and immersed in aqueous electrolyte solution. With a nanomole deposit of pure redox liquid, stable voltammetric responses are obtained. The presence of carbon nanofibers embedded in the mesoporous matrix substantially increases the efficiency of the electrode process and stability under voltammetric conditions. Also well-defined response for diluted redox liquids is obtained. From measurements in a range of different aqueous electrolyte media a gradual transition from anion transfer dominated to cation transfer dominated processes is inferred depending on the hydrophilicity of the transferring anion or cation

  9. Optical properties and electrochromic characterization of sol-gel deposited ceria films

    Energy Technology Data Exchange (ETDEWEB)

    Oezer, N. [Department of Materials Science and Mineral Engineering, University of California, 94720-1760 Berkeley, CA (United States)

    2001-06-01

    Ceria (CeO{sub 2}) films were deposited by the sol-gel spin coating process and optical and electrochromic properties have been investigated. Ceria coating solutions were prepared using cerium ammonium nitrate and ethanol. The films were characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), UV-visible (UV-Vis) spectroscopy and cyclic voltammetry. XRD analysis of the films showed that they had a cerianite structure for heat treatment temperatures at or above 450C. XPS examinations show that the film stoichiometry was CeO{sub 2}. The SEM examinations showed that the surface texture was very uniform and homogeneous. Optical constants of the films were calculated from transmittance (T) spectra using optical spectrometer in the wavelength range of 300-900nm. The refractive index (n), and extinction coefficient (k) values were n=1.82{+-}0.01 and k=0.02{+-}0.002 at 550nm, respectively. The optical bandgap (E{sub g}) of crystalline cerium oxide film was 3.1{+-}0.003eV. The electrochemical behavior investigated in 0.5M LiClO{sub 4} propylene carbonate (PC) electrolyte. Cyclic voltammetry showed a reversible electrochemical insertion or extraction of the Li{sup +} ions maintaining a high optical transmissivity. Spectroelectrochemistry showed that these films could be used as optically passive counter-electrode in transmissive electrochromic devices.

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

    International Nuclear Information System (INIS)

    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 0.1 M phosphate buffer solution (PBS) at pH 7.0 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 3 Sb/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. - Highlights: • A voltammetric nanosensor was prepared using nanoparticles of WO3 and CNTs. • A selective quantification of paracetamol was carried out in the presence of AA. • A linear plot was obtained for current responses versus concentrations over the range from 1.0 × 10−9 to 2.0 × 10−7 M. • A detection limit of 554 pM was obtained for paracetamol using the proposed nanosensor. • An accurate quantification makes the proposed nanosensor of great interest for public health

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

    Energy Technology Data Exchange (ETDEWEB)

    Baytak, Aysegul Kutluay; Duzmen, Sehriban; Teker, Tugce; Aslanoglu, Mehmet, E-mail: maslanoglu@harran.edu.tr

    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 (WO{sub 3}) 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 (WO{sub 3}NPs/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 0.1 M phosphate buffer solution (PBS) at pH 7.0 using square wave voltammetry (SWV). The peak current increased linearly with the concentration of PR in the range of 1.0 × 10{sup −9}–2.0 × 10{sup −7} M. The detection limit (LOD) was 5.54 × 10{sup −11} M (based on 3 S{sub b}/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. - Highlights: • A voltammetric nanosensor was prepared using nanoparticles of WO{sub 3} and CNTs. • A selective quantification of paracetamol was carried out in the presence of AA. • A linear plot was obtained for current responses versus concentrations over the range from 1.0 × 10{sup −9} to 2.0 × 10{sup −7} M. • A detection limit of 554 pM was obtained for paracetamol using the proposed nanosensor. • An accurate quantification makes the proposed nanosensor of great interest for public health.

  12. Direct electrochemistry of glucose oxidase on the hydroxyapatite/Nafion composite film modified electrode and its application for glucose biosensing

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A novel glucose biosensor was constructed by immobilizing the glucose oxidase(GOD) on a hydroxyapatite(HAp)/Nafion composite film modified glassy carbon electrode(GCE) and applied to the highly selective and sensitive determination of glucose.With the cooperation of HAp and Nafion,the composite film played an important role in enhancing the stability and sensitivity of the biosensor.The results demonstrate that the GOD adsorbed onto the HAp/Nafion composite film exhibits a pair of welldefined nearly reversible redox peaks and fine catalysis to the oxidation of glucose companied with the consumption of dissolved oxygen.On the basis of the decrease of the reduction current of dissolved oxygen at the applied potential of -0.80 V(vs.SCE) upon the addition of glucose,the concentration of glucose could be detected sensitively and selectively.The decreased reduction current was linear with the concentration of glucose in the range of 0.12―2.16 mM.The detection limit and sensitivity were 0.02 mM(S/N=3) and 6.75 mA·M-1,respectively.All the results demonstrate that HAp/Nafion composite film provides a novel and efficient platform for the immobilization of enzymes and realizes the direct electrochemistry.The composite materials should have potential applications in the fabrication of third-generation biosensors.

  13. Direct electrochemistry of glucose oxidase on the hydroxyapatite/Nafion composite film modified electrode and its application for glucose biosensing

    Institute of Scientific and Technical Information of China (English)

    MA RongNa; WANG Bin; LIU Yan; LI Jing; ZHAO Qian; WANG GuoTao; JIA WenLi; WANG HuaiSheng

    2009-01-01

    A novel glucose biosensor was constructed by immobilizing the glucose oxidase (GOD) on a hydroxyapatite (Hap)/Nafion composite film modified glassy carbon electrode (GCE) and applied to the highly selective and sensitive determination of glucose.With the cooperation of Hap and Nation,the composite film played an important role in enhancing the stability and sensitivity of the biosensor.The results demonstrate that the GOD adsorbed onto the Hap/Nation composite film exhibits a pair of welldefined nearly reversible redox peaks and fine catalysis to the oxidation of glucose companied with the consumption of dissolved oxygen.On the basis of the decrease of the reduction current of dissolved oxygen at the applied potential of-0.80 V (vs.SCE) upon the addition of glucose,the concentration of glucose could be detected sensitively and selectively.The decreased reduction current was linear with the concentration of glucose in the range of 0.12-2.16 mM.The detection limit and sensitivity were 0.02 mM (S/N=3) and 6.75 mA·M~(-1),respectively.All the results demonstrate that Hap/Nafion composite film provides a novel and efficient platform for the immobilization of enzymes end realizes the direct electrochemistry.The composite materials should have potential applications in the fabrication of third-generation biosensors.

  14. Electrochemical and corrosion behavior of electrode materials on the basis of compositions of ruthenium dioxide and base metal oxides

    International Nuclear Information System (INIS)

    The effect of the active coating composition on the electrochemical and corrosion behavior of the electrode materials on the basis of the metal oxides (M = Ru, Ti, Ta, Nb, Cr, Co, W, Mo and Zr) under the conditions of the chlorine electrolysis is studied with the purpose of improving and developing new anode materials. It is shown, that certain ternary systems on the basis of the ruthenium oxide ad oxides of the studied transition metals are not second by their electrochemical and corrosion characteristics to the ruthenium-titanium anodes of the standard composition (30 mol% RuO2 + 70 mol% TiO2), though the RuO2 content therein may be by three times lesser

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

    Science.gov (United States)

    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

  16. Paper-based energy-storage devices comprising carbon fiber-reinforced polypyrrole-cladophora nanocellulose composite electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Razaq, Aamir; Sjoedin, Martin; Stroemme, Maria; Mihranyan, Albert [Nanotechnology and Functional Materials, Department of Engineering Sciences, Uppsala (Sweden); Department of Chemistry, Angstroem Laboratory, Uppsala (Sweden); Nyholm, Leif [Department of Chemistry, Angstroem Laboratory, Uppsala (Sweden)

    2012-04-15

    Composites of polypyrrole (PPy) and Cladophora nanocellulose, reinforced with 8 {mu}m-thick chopped carbon filaments, can be used as electrode materials to obtain paper-based energy-storage devices with unprecedented performance at high charge and discharge rates. Charge capacities of more than 200 C g{sup -1} (PPy) are obtained for paper-based electrodes at potential scan rates as high as 500 mV s{sup -1}, whereas cell capacitances of {proportional_to}60-70 F g{sup -1} (PPy) are reached for symmetric supercapacitor cells with capacitances up to 3.0 F (i.e.,0.48 F cm{sup -2}) when charged to 0.6 V using current densities as high as 31 A g{sup -1} based on the PPy weight (i.e., 99 mA cm{sup -2}). Energy and power densities of 1.75 Wh kg{sup -1} and 2.7 kW kg{sup -1}, respectively, are obtained when normalized with respect to twice the PPy weight of the smaller electrode. No loss in cell capacitance is seen during charging/discharging at 7.7 A g{sup -1} (PPy) over 1500 cycles. It is proposed that the nonelectroactive carbon filaments decrease the contact resistances and the resistance of the reduced PPy composite. The present straightforward approach represents significant progress in the development of low-cost and environmentally friendly paper-based energy-storage devices for high-power applications. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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). PMID:26263060

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

    Science.gov (United States)

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

    2015-05-15

    Titanium dioxide (TiO2)/ activated carbon (AC) composite materials, as capacitive deionization electrodes, were prepared by a two-step microwave-assisted ionothermal synthesis method. The electrosorption capacity of the composite electrodes was studied and the effects of AC characteristics were explored. These effects were investigated by multiple analytical techniques, including X-ray photoelectron spectroscopy, thermogravimetry analysis and electrochemical impedance spectroscopy, etc. The experimental results indicated that the electrosorption capacity of the TiO2/AC composite electrode is dependent on the characteristics of AC including the pore structure and the surface property. An enhancement in electrosorption capacity was observed for the TiO2/AC composite electrode prepared from the AC with higher mesopore content and less hydrophilic surface. This enhancement is due to the deposition of anatase TiO2 with suitable amount of Ti-OH. On the other hand, a decline in electrosorption capacity was observed for the TiO2/AC composite electrode prepared from the AC with higher micropore content and highly hydrophilic surface. High content of hydrogen bond complex formed between the functional group on hydrophilic surface with H2O, which will slow down the TiO2 precursor-H2O reaction. In such situation, the effect of TiO2 becomes unfavorable as the loading amount of TiO2 is less and the micropore can also be blocked. PMID:25576198

  20. Designer electrode interfaces simultaneously comprising three different metal nanoparticle (Au, Ag, Pd)/carbon microsphere/carbon nanotube composites: progress towards combinatorial electrochemistry.

    Science.gov (United States)

    Dai, Xuan; Wildgoose, Gregory G; Compton, Richard G

    2006-11-01

    In this report gold, silver and palladium metal nanoparticles are separately supported on glassy carbon microspheres (GCM) using bulk electroless deposition techniques to produce three different materials labelled as GCM-Au, GCM-Ag and GCM-Pd respectively. These three materials are then combined together into a composite film on a glassy carbon (GC) electrode surface using multiwalled carbon nanotubes (MWCNTs). The MWCNTs serve to not only mechanically support this composite film as a "binder" but they also help to "wire up" each modified GCM to the underlying substrate. The intelligently designed structure of this electrode interface allows this single modified electrode to simultaneously behave as if it were a macrodisc electrode constructed of gold, silver or palladium, whilst using only a fraction of the equivalent amount of these precious metals. Furthermore this unique structure allows the possibility of combinatorial electrochemistry to be realised using a relatively facile electrode construction which avoids the problems of alloy formation, co-deposition and the formation of bimetallic species. For instance a mixture of several different analytes, which can each only be detected on a different specific substrate, can simultaneously be determined using one electrode in a single voltammetric experiment! Alternatively a substrate could undergo electrocatalytic reactions on one substrate, whilst the products, and hence the progress of this reaction, can be studied at a different substrate simultaneously at the same electrode surface. Proof-of-concept examples are presented herein and the designer electrode interface is shown to produce analytical responses to model target analytes such as hydrazine, bromide and thallium(I) ions that are comparable, if not better, than those obtained at metal macrodisc electrodes and even at other state-of-the-art nanoparticle modified electrodes. PMID:17066193

  1. Redox properties of doped and supported copper-ceria catalysts.

    Science.gov (United States)

    Beckers, Jurriaan; Rothenberg, Gadi

    2008-12-14

    Copper-doped ceria catalysts feature in a variety of catalytic reactions. One important application is selective hydrogen combustion via oxygen exchange, which forms the basis of cyclic oxidative dehydrogenation. This paper describes the synthesis of monophasic (doped) and biphasic (supported) Cu-ceria catalysts, that are then characterized using a combination of temperature programmed reduction (TPR) and X-ray diffraction (XRD) methods. The catalysts are analyzed both as fresh samples and after redox cycling at 550-800 degrees C. TPR and XRD characterization clarify the role of the active sites on the catalyst surface and the copper-ceria interactions. Depending on the catalyst type, reduction occurs at approximately 110 degrees C, approximately 150 degrees C, or approximately 190 degrees C. The reduction at 110 degrees C is ascribed to highly dispersed copper species doped in the ceria lattice, and that at 190 degrees C to CuO crystallites supported on ceria. Remarkably, both types converge to the 150 degrees C feature after redox cycling. The reduction temperature of the doped catalyst increases after redox cycling, indicating that stable Cu clusters form at the surface. Conversely, the reduction temperature of the "supported" catalyst decreases after redox cycling, and the CuO crystallites disappear. With this knowledge, a copper-doped ceria catalyst is analyzed after application in selective hydrogen combustion (16 consecutive redox cycles at 550 degrees C). No CuO crystallites are observed, and the sample reduces at approximately 110 degrees C. This suggests that copper-doped ceria is the active oxygen exchange phase in selective hydrogen combustion. PMID:19030619

  2. Comparative Study of Different Cross-Linking Agents for the Immobilization of Functionalized Carbon Nanotubes within a Chitosan Film Supported on a Graphite−Epoxy Composite Electrode

    OpenAIRE

    Pauliukaite, Rasa; Ghica, Mariana Emilia; Fatibello-Filho, Orlando; Brett, Christopher M. A.

    2009-01-01

    The effectiveness of immobilization of functionalized carbon nanotubes into chitosan using different cross-linking agents has been evaluated. The cross-linkers used were glyoxal (GO), glutaraldehyde (GA), epichlorohydrin (ECH), and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide together with N-hydroxysuccinimide (EDC-NHS), and the nanotubes were retained on graphite epoxy resin composite electrodes. The nanotube modified electrodes have been characterized by cyclic voltammetry (CV) and electr...

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

    OpenAIRE

    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 r...

  4. Effect of Elemental Composition on the Structure, Electrochemical Properties, and Ozone Production Activity of Ti/SnO2-Sb-Ni Electrodes Prepared by Thermal Pyrolysis Method

    Directory of Open Access Journals (Sweden)

    Hamed Shekarchizade

    2011-01-01

    Full Text Available Ti/SnO2-Sb-Ni electrodes with various Ni- and Sb-doping levels have been prepared by dip-coating thermal pyrolysis procedure, and their simultaneous electrochemical ozone production (EOP and oxygen evolution reaction (OER were investigated. The effects of electrode composition on the nanostructure, morphology, electrochemical behavior, kinetic parameters, and lifetime of the electrodes were systematically studied using X-ray diffraction, scanning electron microscopy, cyclic voltammetry, linear sweep voltammetry, and chronopotentiometry. Dissolved ozone was produced in a quartz cell and its concentration was monitored by in situ UV spectrophotometry. The presence of small amounts of Ni (Ni : Sn atomic ratio of 0.2 : 100 gives valuable characteristics to the electrodes such as increasing EOP activity and service life. Higher Ni concentrations increase the electrode film resistance and decrease its capacitance, roughness factor, and service life, while increasing Sb level up to 12 atom% improves the electrode performance with respect to these parameters. Nevertheless, the Sb/Sn atomic ratio of more than 2% reduces the EOP current efficiency in favor of OER. The optimum composition of the electrode for EOP was determined to be Sb/Sn and Ni/Sn atomic ratios of 2% and 0.2%, respectively. The highest current efficiency was 48.3% in 0.1 M H2SO4 solution at room temperature.

  5. Cathodic Tb(III) chelate electrochemiluminescence at oxide-covered magnesium and n-ZnO:Al/MgO composite electrodes

    International Nuclear Information System (INIS)

    Some of the luminescent aromatic Tb(III) chelates can be excited at oxide-covered magnesium and n-ZnO:Al/MgO composite electrodes by cathodic pulse polarization in aqueous solution. This is based on the cathodic injection of hot electrons into the aqueous electrolyte solution and successive redox reactions in one-electron steps resulting in the excited states of the chelates. Due to the relatively long luminescence lifetime of multidentate Tb(III) chelates, these chelates can be very sensitively detected by time-resolved electrochemiluminescence (TR-ECL) measurements using the present working electrodes. Thus, metal or highly doped semiconductor electrodes coated by a thin MgO film lend themselves as nontransparent or in some cases, even optically transparent working electrodes for generation of free radicals and cathodic ECL in aqueous solution. The results suggest that also other even more efficient optically transparent composite tunnel emission electrodes than the present n-ZnO:Al/MgO electrodes could be constructed by coating n-ZnO:Al glass electrodes with other wide band gap insulating oxides

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

    Science.gov (United States)

    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

  7. Effect of Ca and Li additions on densification and electrical conductivity of 10 mol% gadolinia-doped ceria prepared by the coprecipitation technique; Efeito de adicoes de litio e calcio na densificacao e na condutividade eletrica da ceria-10% mol gadolinia preparada pela tecnica de co-precipitacao

    Energy Technology Data Exchange (ETDEWEB)

    Porfirio, T.C.

    2010-07-01

    Ceria containing rare-earth ceramics are potential candidates for application in intermediate-temperature solid oxide fuel cells. One of the main problems related to these ceramic materials is their relatively low sinterability. In this work, the effects of Ca and Li additions on densification and electrical conductivity of 10 mol% gadolinia-doped ceria was investigated. Ceramic compositions containing 1.5 mol% Ca or Li were prepared by the oxalate coprecipitation technique. Results of sintered density and electrical conductivity were compared to those of ceramic samples obtained by solid state reactions showing the effects of the synthesis method on densification and total electrical conductivity of the sintered materials. (author)

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

    Science.gov (United States)

    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.

  9. Synthesis of graphene oxide based CuO nanoparticles composite electrode for highly enhanced nonenzymatic glucose detection.

    Science.gov (United States)

    Song, Jian; Xu, Lin; Zhou, Chunyang; Xing, Ruiqing; Dai, Qilin; Liu, Dali; Song, Hongwei

    2013-12-26

    CuO nanoparticles (NPs) based graphene oxide (CuO/GO) composites with different CuO NPs loading amount as well as pure CuO NPs with different hydrothermal temperatures were synthesized using a hydrothermal method. Transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Raman spectroscopy were employed to characterize the morphology and structures of our samples. The influence of hydrothermal temperature, GO sheet, and loading amount of CuO on particle size and structure of CuO was systemically investigated. The nonenzymatic biosensing properties of CuO/GO composites and CuO NPs toward glucose were studied based on glassy carbon electrode (GCE). The sensing properties of CuO NPs were improved after loading on GO sheets. The CuO/GO composites with saturated loading of the CuO NPs exhibited the best nonenzymatic biosensing behavior. It exhibited a sensitivity of 262.52 μA mM(-1) cm(-2) to glucose with a 0.69 μM detection limit (S/N = 3) and a linear range from 2.79 μM to 2.03 mM under a working potential of +0.7 V. It also showed outstanding long term stability, good reproducibility, excellent selectivity, and accurate measurement in real serum sample. It is believed that CuO/GO composites show good promise for further application on nonenzymatic glucose biosensors. PMID:24182328

  10. Li4Ti5O12/C composite electrode material synthesized involving conductive carbon precursor for Li-ion battery

    International Nuclear Information System (INIS)

    Li4Ti5O12/C composite was synthesized via a simple solid-state reaction using Super-P-Li conductive carbon black as reaction precursor. The prepared samples were characterized by XRD, SEM, TG and granularity analysis and their electrochemical performance was also investigated in this work. The results showed that the Li4Ti5O12/C composite had a spinel crystal structure and the particle size of the powder was uniformly distributed with an average particle size of 480 nm. The conductive carbon was embedded in the Li4Ti5O12 particles without incorporation in the Li4Ti5O12 crystal lattice during the sintering process. The added Super-P-Li carbon played an important role in improving the electronic conductivity and electrochemical performance of the Li4Ti5O12/C electrode. Compared with raw Li4Ti5O12, the Li4Ti5O12/C composite exhibited higher rate capability and excellent reversibility. The initial discharge capacity of Li4Ti5O12/C composite was 174.5 mAh g-1 at 0.5C and 169.3 mAh g-1 at 1C.

  11. Factors influencing MnO2/multi-walled carbon nanotubes composite's electrochemical performance as supercapacitor electrode

    International Nuclear Information System (INIS)

    Poor crystallined α-MnO2 grown on multi-walled carbon nanotubes (MWCNTs) by reducing KMnO4 in ethanol are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Brunauer-Emmett-Telle (BET) surface area measurement, which indicate that MWCNTs are wrapped up by poor crystalline MnO2 and BET areas of the composites maintain the same level of 200 m2 g-1 as the content of MWCNTs in the range of 0-30%. The electrochemical performances of the MnO2/MWCNTs composites as electrode materials for supercapacitor are evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge measurement in 1 M Na2SO4 solution. At a scan rate of 5 mV s-1, rectangular shapes could only be observed for the composites with higher MWCNTs contents. The effect of additional conductive agent KS6 on the electrochemical behavior of the composites is also studied. With a fixed carbon content of 25% (MWCNTs included), MnO2 with 20% MWCNTs and 5% KS6 has the highest specific capacitance, excellent cyclability and best rate capability, which gives the specific capacitance of 179 F g-1 at a scan rate of 5 mV s-1, and remains 114.6 F g-1 at 100 mV s-1.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  14. Fe{sub 3}O{sub 4}/carbon coated silicon ternary hybrid composite as supercapacitor electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Ilgeun; Kim, Myeongjin; Kim, Jooheon, E-mail: jooheonkim@cau.ac.kr

    2015-02-15

    Highlights: • Silicon was covered with carbon by thermal vapor deposition. • Carbon layer prevent exposure of silicon to reactive electrolyte. • Fe{sub 3}O{sub 4} contents in the composites optimized for electrochemical performance. • Fe{sub 3}O{sub 4}/carbon coated Si exhibits higher electrochemical performance than raw Si. - Abstract: In this study, Fe{sub 3}O{sub 4}/carbon-coated Si ternary hybrid composites were fabricated. A carbon layer was directly formed on the surface of Si by the thermal vapor deposition. The carbon-coating layer not only prevented the contact between Si and reactive electrolyte but also provided anchoring sites for the deposition of Fe{sub 3}O{sub 4}. Fe{sub 3}O{sub 4} nanoparticles were deposited on the surface of carbon-coated Si by the hydrazine reducing method. The morphology and structure of Fe{sub 3}O{sub 4} and carbon layer were characterized via X-ray diffractometry, field emission scanning electron microscopy, field emission transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analyses. These characterizations indicate that a carbon layer was fully coated on the Si particles, and Fe{sub 3}O{sub 4} particles were homogeneously deposited on the carbon-coated Si particles. The Fe{sub 3}O{sub 4}/carbon-coated Si electrode exhibited enhanced electrochemical performance, attributed to the high conductivity and stability of carbon layer and pseudocapacitive reaction of Fe{sub 3}O{sub 4}. The proposed ternary-hybrid composites may be potentially useful for the fabrication of high-performance electrodes.

  15. Ascorbate electro-oxidation by modified electrodes: Polypyrrole and polypyrrole/Ni(OH){sub 2} composite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues da Silva, Marcelo [Faculdade de Engenharia/Colegio Tecnico Industrial, UNESP, CP 473, 17033-360 Bauru, SP (Brazil); Ferreira, Marcelo Silva [Departamento de Quimica, Centro de Ciencias Exatas, UEL, CP 6001, 86051-980 Londrina, PR (Brazil); Dall' Antonia, Luiz Henrique, E-mail: luizh@uel.br [Departamento de Quimica, Centro de Ciencias Exatas, UEL, CP 6001, 86051-980 Londrina, PR (Brazil)

    2012-08-01

    The present paper describes the utilization of polypyrrole and the composite of polypyrrole doped with nickel hydroxide modified electrodes toward the catalytic oxidation of ascorbate. Films were potentiostatically deposited onto a glassy carbon surface and Fluor-doped tin oxide glass for different times. The physical characterization was performed using the low angle X-ray diffraction technique. Furthermore, the films were electrochemically characterized using cyclic voltammetry. The X-ray diffraction results show the existence of different polymorphic phases of nickel hydroxide in the polymer matrix, and the {beta}-Ni(OH){sub 2} phase appears to be dominant. The cyclic voltammetry profile in KOH solution shows the presence of two redox peaks that are related to the Ni{sup II}/Ni{sup III} and Ni{sup III}/Ni{sup II} couples, at approximately 0.5 and 0.35 V, respectively. The reversible electro-oxidation of ascorbate was observed on the surface of the polypyrrole and composite films. The analytical curves obtained using voltammetric techniques show a linear relationship between the faradaic current and the increase of the ascorbic acid concentration. The sensitivity of these films, which is obtained from the slope of the analytical curves, shows that the composite film is more electroactive than the polypyrrole film: 133.4 mA L mol{sup -1} cm{sup -2} and 83.8 mA L mol{sup -1} cm{sup -2}, respectively. The rate constants of the catalytic ascorbate electro-oxidation were also reported, where the mean values were found to be 217.74 M{sup -1} s{sup -1} and 54.37 M{sup -1} s{sup -1}, for the composite and polypyrrole films, respectively. The low cost of polypyrrole doped with Ni(OH){sub 2} composite electrodes presents a more selective and high sensitivity to determine ascorbic acid concentration. - Highlights: Black-Right-Pointing-Pointer Electrochemical synthesis of polypyrrole and nickel hydroxide composite thin films Black-Right-Pointing-Pointer High sensitivity

  16. Highly conductive alumina/NCN composites electrodes fabricated by gelcasting and reduction-sintering-An electrochemical behavior study in aggressive environments

    International Nuclear Information System (INIS)

    A novel highly conductive alumina/nano-carbon network composites (alumina/NCN composites) was fabricated by gelcasting and reduction-sintering method under argon atmosphere. The electrochemical behaviors of the alumina/NCN composites were studied systematically in some aggressive solutions (HCl, H2SO4, HNO3, NaOH, and KOH), using potentiodynamic polarization and chronoamperometry and X-ray diffraction and SEM observations. The results showed that the electrochemical stability and reproducibility of the composite electrodes in these diluted acids and alkalis were very good and had, in some extent, an electro-catalytic activity toward formation of hydrogen evolution and reduction of dissolved oxygen in aqueous solutions in comparison with a commercial graphite electrode. In addition, the pyrolyzed nano-carbon contents, size, and shape in the alumina matrix, have greatly effects on the electrochemical performances and electrode reactions in these solutions. It is found that the minimal residual carbon content of 0.62 wt.% in the matrix is enough to improve electrochemical performances and avoid to loss the ceramics physical properties at the same time. When the additional potential in all the tested electrolytes was at +1700 mV (vs. SCE), alumina particles at the electrode surface were not observed to dissolve into solution in this case, indicating the material being suitable for electrodes in aggressive solutions

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

    Science.gov (United States)

    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

  18. Effects of bath composition on the morphology of electroless-plated Cu electrodes for hetero-junctions with intrinsic thin layer solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Woon Young [Surface Technology R& BD Group, Korea Institute of Industrial Technology (KITECH), Gaetbeol-ro 156, Yeonsu-gu, Incheon 406-840 (Korea, Republic of); Lee, Yu Jin [Surface Technology R& BD Group, Korea Institute of Industrial Technology (KITECH), Gaetbeol-ro 156, Yeonsu-gu, Incheon 406-840 (Korea, Republic of); Department of Materials Science & Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Lee, Min Hyung, E-mail: minhyung@kitech.re.kr [Surface Technology R& BD Group, Korea Institute of Industrial Technology (KITECH), Gaetbeol-ro 156, Yeonsu-gu, Incheon 406-840 (Korea, Republic of)

    2015-07-31

    The morphology of an electroless-plated Cu electrode was investigated as a function of bath composition. To enhance the selectivity of Cu electrode deposition on the surface of an indium tin oxide layer, a Ti/Cu multi-layer was deposited as a Cu electrode seed layer by physical vapor deposition, and then electroless plating was performed using various complexing agents and a surfactant. The degree of selectivity was effectively influenced by the type of complexing agent. The electroless plating solution containing N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine (THPED) as complexing agent showed excellent selective growth of the Cu electrode as compared to the solution containing ethylenediaminetetraacetic acid. Even though THPED led to better selective growth of the electroless-plated Cu electrode, the aspect ratio of electrode lateral growth was about 2.7 times that of vertical growth. By adding a nonionic surfactant, the ratio between vertical growth rate and lateral growth rate was improved about 4.6 times. The Cu–THPED electroless plating with nonionic surfactant provided a drastic decrease in lateral growth rate, compared with the Cu–THPED electroless plating bath excluding nonionic surfactant. The Cu–THPED solution including nonionic surfactant is a promising composition of electroless plating solution for the clear selective plating of Cu electrodes on hetero-junctions with intrinsic thin layer solar cells. - Highlights: • Selective electroless plating (SEP) depends on binding strength of complexing agent. • The SEP was performed using Cu-N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine. • A surfactant is able to remove hydrogen bubbles on Cu electrode surface. • The growth of Cu electrode was improved in vertical direction by adding surfactant.

  19. Effects of bath composition on the morphology of electroless-plated Cu electrodes for hetero-junctions with intrinsic thin layer solar cell

    International Nuclear Information System (INIS)

    The morphology of an electroless-plated Cu electrode was investigated as a function of bath composition. To enhance the selectivity of Cu electrode deposition on the surface of an indium tin oxide layer, a Ti/Cu multi-layer was deposited as a Cu electrode seed layer by physical vapor deposition, and then electroless plating was performed using various complexing agents and a surfactant. The degree of selectivity was effectively influenced by the type of complexing agent. The electroless plating solution containing N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine (THPED) as complexing agent showed excellent selective growth of the Cu electrode as compared to the solution containing ethylenediaminetetraacetic acid. Even though THPED led to better selective growth of the electroless-plated Cu electrode, the aspect ratio of electrode lateral growth was about 2.7 times that of vertical growth. By adding a nonionic surfactant, the ratio between vertical growth rate and lateral growth rate was improved about 4.6 times. The Cu–THPED electroless plating with nonionic surfactant provided a drastic decrease in lateral growth rate, compared with the Cu–THPED electroless plating bath excluding nonionic surfactant. The Cu–THPED solution including nonionic surfactant is a promising composition of electroless plating solution for the clear selective plating of Cu electrodes on hetero-junctions with intrinsic thin layer solar cells. - Highlights: • Selective electroless plating (SEP) depends on binding strength of complexing agent. • The SEP was performed using Cu-N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine. • A surfactant is able to remove hydrogen bubbles on Cu electrode surface. • The growth of Cu electrode was improved in vertical direction by adding surfactant

  20. Influence of ceria nanoparticles on chemical structure and properties of segmented polyesters

    International Nuclear Information System (INIS)

    In this work, we present new nanocomposite materials derived from segmented copolyesters, comprising ethylene terephthalate (PET) segments and dimerized linoleic acid (DLA), and nanometric cerium oxide particles (CeO2). Nanoparticles were incorporated in situ during polycondensation in various concentrations, from 0.1 up to 0.6 wt.%. It was found that preparation of nanocomposites in situ, during polycondensation, had no significant influence on changes in segmental composition as determined from 1H and 13C, as well as 2D NMR. Thermal analysis and calculated degree of crystallinity showed that increasing concentration of ceria nanoparticles lead to an increase in mass content of PET crystallites in hard segments. The XRD investigations also showed an increased intensity of characteristic signals with increasing ceria concentration. Simultaneously, the incorporation of CeO2 led to an increase in tensile strength and elongation at break, indicating a reinforcing and plasticizing effect of ceria nanoparticles. However, the modulus at 10% strain decreased with increasing amount of nanoparticles. The in vitro culture of human cardiac progenitor cells (hCPCs) on the new materials indicated a homogenous cell displacement across the samples after 5 days with no signs of cytotoxicity, indicating good biocompatibility in vitro of CeO2-based nanocomposites and a potential for biomedical applications. - Highlights: • Successful preparation of nanocomposites containing Ce02 in PET–DLA was carried out. • CeO2 increased crystallinity and enhanced mechanical properties of nanocomposites. • The PET–DLA nanocomposites supported adhesion and growth of hCPCs

  1. Influence of ceria nanoparticles on chemical structure and properties of segmented polyesters

    Energy Technology Data Exchange (ETDEWEB)

    El Fray, M., E-mail: mirfray@zut.edu.pl [West Pomeranian University of Technology, Szczecin, Polymer Institute, Division of Biomaterials and Microbiological Technologies, Al. Piastów 45, 70-311 Szczecin (Poland); Strzalkowska, D. [West Pomeranian University of Technology, Szczecin, Polymer Institute, Division of Biomaterials and Microbiological Technologies, Al. Piastów 45, 70-311 Szczecin (Poland); Mandoli, C. [International Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Pagliari, F.; Di Nardo, P. [Laboratory of Molecular and Cellular Cardiology, Department of Internal Medicine, University of Rome “Tor Vergata”, Rome 00133 (Italy); Traversa, E. [International Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2015-08-01

    In this work, we present new nanocomposite materials derived from segmented copolyesters, comprising ethylene terephthalate (PET) segments and dimerized linoleic acid (DLA), and nanometric cerium oxide particles (CeO{sub 2}). Nanoparticles were incorporated in situ during polycondensation in various concentrations, from 0.1 up to 0.6 wt.%. It was found that preparation of nanocomposites in situ, during polycondensation, had no significant influence on changes in segmental composition as determined from {sup 1}H and {sup 13}C, as well as 2D NMR. Thermal analysis and calculated degree of crystallinity showed that increasing concentration of ceria nanoparticles lead to an increase in mass content of PET crystallites in hard segments. The XRD investigations also showed an increased intensity of characteristic signals with increasing ceria concentration. Simultaneously, the incorporation of CeO{sub 2} led to an increase in tensile strength and elongation at break, indicating a reinforcing and plasticizing effect of ceria nanoparticles. However, the modulus at 10% strain decreased with increasing amount of nanoparticles. The in vitro culture of human cardiac progenitor cells (hCPCs) on the new materials indicated a homogenous cell displacement across the samples after 5 days with no signs of cytotoxicity, indicating good biocompatibility in vitro of CeO{sub 2}-based nanocomposites and a potential for biomedical applications. - Highlights: • Successful preparation of nanocomposites containing Ce0{sub 2} in PET–DLA was carried out. • CeO{sub 2} increased crystallinity and enhanced mechanical properties of nanocomposites. • The PET–DLA nanocomposites supported adhesion and growth of hCPCs.

  2. Synthesis and characterization of electrodeposited samaria and samaria-doped ceria thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lair, V., E-mail: virginie-lair@ens.chimie-paristech.f [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie, LECIME, CNRS UMR 7575-ENSCP Chimie Paristech, 11rue Pierre et Marie Curie, 75231 Paris cedex 05 (France); Zivkovic, L.S. [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie, LECIME, CNRS UMR 7575-ENSCP Chimie Paristech, 11rue Pierre et Marie Curie, 75231 Paris cedex 05 (France); The Vinca Institute of Nuclear Sciences, University of Belgrade, PO Box 522, 11 001Belgrade (Serbia); Lupan, O. [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie, LECIME, CNRS UMR 7575-ENSCP Chimie Paristech, 11rue Pierre et Marie Curie, 75231 Paris cedex 05 (France); Department of Microelectronics and Semiconductor Devices, Technical University of Moldova, 168 Stefan cel Mare Blvd., Chisinau, MD-2004, Republic of Moldova (Moldova, Republic of); Ringuede, A. [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie, LECIME, CNRS UMR 7575-ENSCP Chimie Paristech, 11rue Pierre et Marie Curie, 75231 Paris cedex 05 (France)

    2011-04-30

    Graphical abstract: . Display Omitted Highlights: {yields} It reported hereby on the electrochemical deposition of pure Sm{sub 2}O{sub 3} and samaria-doped ceria SDC-films at low-temperature (30 {sup o}C). {yields} A detailed analysis of the composition, structural, morphological and vibrational properties of SDC electrodeposited films are presented. {yields} Effects of thermal annealing on the evolution of the material properties of Sm{sub 2}O{sub 3} and SDC by means of XRD and Raman spectroscopy were analyzed. {yields} Presented results indicate that electrochemical Sm{sub 2}O{sub 3} and SDC-films are good for further studies in applications as protective coatings against corrosion of different metallic surfaces and in solid oxide fuel cell. - Abstract: Samaria (Sm{sub 2}O{sub 3}) and samaria-doped ceria (SDC) films are electrochemically deposited on stainless steel in view of a potential use in solid oxide fuel cells. As it is possible to deposit separately pure ceria (CeO{sub 2}) and pure samaria (Sm{sub 2}O{sub 3}) in similar conditions, SDC films were successfully obtained in one electrochemical conditions set. Thin films have been fabricated at low-temperature (30 {sup o}C) by applying a cathodic potential of -0.8 V/SCE, for 2 h. Structural and morphological properties of electrodeposited films have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), techniques and Raman spectroscopy. Special attention has been focused on the Raman spectroscopy study to emphasize the effect of heat treatment and samarium doping. Despite cracks, single SDC phase was obtained crystallizing in a cubic symmetry.

  3. A red-to-gray poly(3-methylthiophene) electrochromic device using a zinc hexacyanoferrate/PEDOT:PSS composite counter electrode

    Energy Technology Data Exchange (ETDEWEB)

    Hong, S.-F. [Department of Bio-Industrial Mechatronics Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chen, L.-C., E-mail: chenlinchi@ntu.edu.t [Department of Bio-Industrial Mechatronics Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Bioenergy Research Center, National Taiwan University, Taipei 10617, Taiwan (China)

    2010-04-30

    In this paper, we describe a novel red-to-gray poly(3-methylthiophene) (PMeT) electrochromic device (ECD) with the aid of a zinc hexacyanoferrate (ZnHCF)/PEDOT:PSS counter electrode. The application of ZnHCF to an ECD is first reported. ZnHCF has long suffered from poor deposition yield problem, but we demonstrate that a robust ZnHCF film can be prepared by spin coating of a liquid suspension composed of ZnHCF nanoparticles and PEDOT:PSS ink on ITO. It was found that the ZnHCF/PEDOT:PSS composite worked much better with PMeT than pure ZnHCF or pure PEDOT:PSS from both electrochemical and optical aspects. With a LiClO{sub 4}/PC electrolyte, the PMeT ECD having ZnHCF/PEDOT:PSS as its counter electrode could be reversibly switched between its red state (>0.8 V) and its gray state (<0 V). For a 2 cm x 2 cm prototype device, the response time for coloration was less than 1 s. The maximum transmittance modulation of the device could attain 45.3% at 750 nm, which resulted in a corresponding coloration efficiency of 336.8 cm{sup 2}/C. The maximum contrast ratio was 5.45 at 720 nm. In addition, the charge capacity of the ECD could retain 95% of its original value after 10,000 cycles of cyclic voltammetry aging test, although an electrodeposited PMeT film alone could be cycled several hundred times only. To sum up, this work proposes a new, cost-effective transparent counter electrode and brings a stable, high visual-contrast PMeT ECD prototype for further development of a red-color bistable display.

  4. Nano-perovskite carbon paste composite electrode for the simultaneous determination of dopamine, ascorbic acid and uric acid

    International Nuclear Information System (INIS)

    A perovskite, SrPdO3, of the type ABO3 was used in the form of a composite with carbon paste as an electrode (CpE/SrPdO3) for the electrochemical sensing of dopamine (DA) in biological fluids. The CpE/SrPdO3 electrode showed a unique long term stability and low detection limit for (DA) determination. The structural characteristics of the modifier (SrPdO3) that were prepared by a green method revealed a primary orthorhombic perovskite phase of SrPdO3 and a secondary phase of SrPd3O4. The electrocatalytic activity of the CpE/SrPdO3 electrode toward DA oxidation is relatively higher when compared to electrodeposited palladium nanoparticles modified CpE (CpE/Pd) with equivalent loading of Pd4+ salt. The prepared perovskite was characterized by XRD and SEM. Electrochemical characterization of CpE/SrPdO3 was done using cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy. The redox behavior of DA follows a quasi reversible mechanism and two linear ranges of 7–70 μmol L−1 and 90–160 μmol L−1 with low detection limits of 9.3 nmol L−1 and 25 nmol L−1, respectively, and good correlation coefficient of 0.9981 could be determined. The electrocatalytic behavior is explained in terms of an oxygen–surface interaction between the oxygen atoms of the hydroxyl groups and the transition element in the perovskite. The protocol of DA sensing using this method was simple, sensitive and successfully applied for direct determination of DA in human urine samples with excellent recovery results. CpE/SrPdO3 showed also high reproducibility, enhanced sensitivity, selectivity and anti-interference ability

  5. Three-Dimensional BC/PEDOT Composite Nanofibers with High Performance for Electrode-Cell Interface.

    Science.gov (United States)

    Chen, Chuntao; Zhang, Ting; Zhang, Qi; Feng, Zhangqi; Zhu, Chunlin; Yu, Yalin; Li, Kangming; Zhao, Mengyao; Yang, Jiazhi; Liu, Jian; Sun, Dongping

    2015-12-30

    There is an increasing need to synthesize biocompatible nanofibers with excellent mechanical and electrical performance for electrochemical and biomedical applications. Here we report a facile approach to prepare electroactive and flexible 3D nanostructured biomaterials with high performance based on bacterial cellulose (BC) nanofibers. Our approach can coat BC nanofibers with poly(3,4-ethylenedioxythiophene) (PEDOT) by in situ interfacial polymerization in a controllable manner. The PEDOT coating thickness is adjustable by the monomer concentration or reaction time during polymerization, producing nanofibers with a total diameter ranging from 30 to 200 nm. This fabrication process also provides a convenient method to tune different parameters such as the average pore size and electrical conductivity on the demands of actual applications. Our experiments have demonstrated that the 3D BC/PEDOT nanofibers exhibit high specific surface area, excellent mechanical properties, electroactive stability, and low cell cytotoxicity. With electrical stimulation, calcium imaging of PC12 neural cells on BC/PEDOT nanofibers has revealed a significant increase in the percentage of cells with higher action potentials, suggesting an enhanced capacitance effect of charge injection. As an attractive solution to the challenge of designing better electrode-cell interfaces, 3D BC/PEDOT nanofibers promise many important applications such as biosensing devices, smart drug delivery systems, and implantable electrodes for tissue engineering. PMID:26550840

  6. Preparation, Electrochemical Property and Application in Bulk-modified Electrode of Dawson-type Phosphomolybdate-doped Polypyrrole Composite Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A kind of inorganic-organic hybrid semiconductor composite nanoparticles: Dawson-type phosphomolybdatedoped polypyrrole (P2Mo18-PPy) was designed and prepared using microemulsion oxidation-polymerization at room temperature and characterized by TEM and IR. The P2Mo18-PPy was used as a bulk-modifier to fabricate a chemically modified carbon paste electrode(CPE) by direct mixing, which represents the example of polyoxometalates (POMs)-doped semiconductor polymer nanoparticles modified electrode. Both the advantage of POMs-doped polymer and the surface-renewal property of the CPE were fully utilized. The electrochemical behavior of the P2Mo18-PPy bulk-modified CPE(P2Mo18-PPy-CPE) was investigated with cyclic voltammetry. Three couples of reversible redox peaks were observed in the range from + 800 to 0 mV, which corresponded to the reduction and oxidation through two-, four- and six-electron processes, respectively. The P2Mo18-PPY-CPE showed a high electrocatalytic activity for the reduction of nitrite, which expanded the application of POMs-doped semiconductor polymer nanoparticles.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2016-06-15

    Sensitive and selective determination of protein biomarkers remains a significant challenge due to the existence of various biomarkers in human body at a low concentration level. Therefore, new technologies were incessantly steered to detect tiny biomarkers at a low concentration level, yet, it is difficult to develop reliable, stable and sensitive detection methods for disease diagnostics. Therefore, the present study demonstrates a methodology to detect insulin in serum at low levels based on Ag nanoflower (AgNF) decorated reduced graphene oxide (rGO) modified micro-disk electrode arrays (MDEAs). The morphology of AgNF-rGO composite was characterized by scanning electron microscopy, the structure was analyzed using X-ray diffraction patterns and Raman spectra. The hybrid interface exhibited enhanced electrical conductivity when compared with its individual elements and had improved capturing ability for antibody-antigen binding towards insulin detection. In order to measure quantitatively the insulin concentration in PBS and human serum, the change in impedance (ΔZ) from electrochemical impedance spectroscopy was analyzed for various concentrations of insulin in [Fe(CN)6](3-/4-) redox couple. The electrode with adsorbed antibodies showed an increase in ΔZ for the addition of antigen concentrations over a working range of 1-1000ngmL(-1). The detection limits were 50 and 70pgmL(-1) in PBS and human serum, respectively. PMID:26852199

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

    International Nuclear Information System (INIS)

    Highlights: • PU–Si gel is new anion exchanger material synthesized and characterized. • This material used as anion exchange membrane is applied for electroanalytical studies. • The method for detection and determination of AsO43− in traces amounts discussed. • The results are also verified from arsenic analyzer. -- Abstract: 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 (45 s) and working pH range (5–8). The selectivity coefficient values for interfering ions indicate good selectivity for arsenate (AsO43−) over interfering anions. The accuracy of the detection limit results was compared by PCA-Arsenomat

  10. SnO2/ZnO composite structure for the lithium-ion battery electrode

    International Nuclear Information System (INIS)

    In this article, SnO2/ZnO composite structures have been synthesized by two steps hydrothermal method and investigated their lithium storage capacity as compared with pure ZnO. It has been found that these composite structures combining the large specific surface area, stability and catalytic activity of SnO2 micro-crystals, demonstrate the higher initial discharge capacity of 1540 mA h g−1 with a Coulombic efficiency of 68% at a rate of 120 mA h g−1 between 0.02 and 2 V and found much better than that of any previously reported ZnO based composite anodes. In addition, a significantly enhanced cycling performance, i.e., a reversible capacity of 497 mA h g−1 is retained after 40 cycles. The improved lithium storage capacity and cycle life is attributed to the addition of SnO2 structure, which act as good electronic conductors and better accommodation of the large volume change during lithiation/delithiation process. - Graphical abstract: SnO2/ZnO composite structures demonstrate the improved lithium storage capacity and cycle life as compared with pure ZnO nanostructure. Highlights: ► Synthesis of SnO2/ZnO composite structures by two steps hydrothermal approach. ► Investigation of lithium storage capacity. ► Excellent lithium storage capacity and cycle life of SnO2/ZnO composite structures.

  11. Graphene/Nafion composite film modified glassy carbon electrode for simultaneous determination of paracetamol, aspirin and caffeine in pharmaceutical formulations.

    Science.gov (United States)

    Yiğit, Aydın; Yardım, Yavuz; Çelebi, Metin; Levent, Abdulkadir; Şentürk, Zühre

    2016-09-01

    A graphene-Nafion composite film was fabricated on the glassy carbon electrode (GR-NF/GCE), and used for simultaneous determination of paracetamol (PAR), aspirin (ASA) and caffeine (CAF). The electrochemical behaviors of PAR, ASA and CAF were investigated by cyclic voltammetry and square-wave adsorptive anodic stripping voltammetry. By using stripping one for simultaneous determination of PAR, ASA and CAF, their electrochemical oxidation peaks appeared at +0.64, 1.04 and 1.44V, and good linear current responses were obtained with the detection limits of 18ngmL(-1) (1.2×10(-9)M), 11.7ngmL(-1) (6.5×10(-8)M) and 7.3ngmL(-1) (3.8×10(-8)M), respectively. Finally, the proposed electrochemical sensor was successfully applied for quantifying PAR, ASA and CAF in commercial tablet formulations. PMID:27343573

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Emmanuel I. Iwuoha

    2010-10-01

    Full Text Available 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.

  14. Voltammetric and amperometric determination of hydrogen peroxide using a carbon-ceramic electrode modified with a nanohybrid composite made from single-walled carbon nanotubes and silver nanoparticles

    International Nuclear Information System (INIS)

    A nanohybrid composite material was prepared from single-walled carbon nanotubes and silver nanoparticles, and used to fabricate a modified carbon-ceramic electrode. The preparation of the composite is facile and efficient. The nanohybrid composite deposited on the carbon-ceramic electrode was characterized by X-ray diffraction and cyclic voltammetry. The new electrode displays favorable electrocatalytic ability towards hydrogen peroxide (HO2) and can be used to electrocatalytically reduce this species. Under the optimum conditions, the current measured during hydrodynamic amperometry is linearly related to the concentration of H2O2 over the concentration range from 0.01 to 8 mM, with a detection limit of 2 x 10-7 M at a signal-to-noise ratio of 3 and sensitivity of 3.23 μA/mM. The electrode exhibits good reproducibility, long-term stability and negligible interference by dopamine, uric acid, and other important biological compounds. The electrode was successfully applied to the determination of H2O2 in honey samples, and the recovery was 101.2%. (author)

  15. Enhanced mass diffusion phenomena in highly defective doped ceria

    DEFF Research Database (Denmark)

    Esposito, Vincenzo; Ni, De Wei; He, Zeming;

    2013-01-01

    The densification and grain growth of the solid state ionic conductor material Ce0.9Gd0.1O1.95−δ (i.e. GDC10, gadolinium-doped ceria, with Gd 10mol.%) are analysed for nanometric and fine powders of various particle sizes, both in air and in a 9vol.% H2–N2 mixture. Due to a dominant solute drag e...... effect in aliovalent highly doped ceria, the starting morphology of the powders controls the diffusion mechanisms of the material in air. Conversely, highly enhanced densification and grain growth are achieved by firing the materials at reduced temperatures (800...

  16. Electrostatic accumulation and determination of triclosan in ultrathin carbon nanoparticle composite film electrodes

    International Nuclear Information System (INIS)

    A film composed of carbon nanoparticles and poly(diallyldimethylammonium chloride) or CNP-PDDAC is formed in a layer-by-layer deposition process at tin-doped indium oxide (ITO) substrates. Excess positive binding sites within this film in aqueous phosphate buffer at pH 9.5 are quantified by adsorption of iron(III)phthalocyanine tetrasulfonate and indigo carmine. Both anionic redox systems bind with Langmuirian characteristics (K ∼ 105 mol-1 dm3) and show electrochemical reactivity throughout the film at different thicknesses. Therefore, the electrical conductivity in CNP-PDDAC films is good and the positive binding sites are approximately 140 pmol cm-2 per layer. Structural instability of the CNP-PDDAC film in the presence of high concentrations of iron(III)phthalocyanine tetrasulfonate or indigo carmine is observed. Triclosan, a widely used anti-bacterial and anti-fungal agent, exists in aqueous media at pH 9.5 as a negatively charged chlorinated poly-aromatic phenol. Due to the negative charge, triclosan is readily accumulated into CNP-PDDAC films with an efficiency consistent with that expected for simple electrostatic interaction with the cationic binding sites. Oxidation of bound triclosan occurs at 0.6 V versus SCE in a chemically irreversible process. The CNP-PDDAC film electrode is renewed by rinsing in organic solvent and the triclosan oxidation response is shown to correlate with the triclosan concentration in solution from 0.5 to 50 μM. Applications of the CNP-PDDAC film electrode (or improved versions of it) in analysis or in anodic extraction are proposed

  17. Electrostatic accumulation and determination of triclosan in ultrathin carbon nanoparticle composite film electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Amiri, Mandana [Department of Chemistry, Sharif University of Technology, Teheran (Iran, Islamic Republic of); Shahrokhian, Saeed [Department of Chemistry, Sharif University of Technology, Teheran (Iran, Islamic Republic of); Psillakis, Elefteria [Laboratory of Aquatic Chemistry, Department of Environmental Engineering, Technical University of Crete, Polytechnioupolis, 73100 Chania-Crete (Greece); Marken, Frank [Department of Chemistry, University of Bath, Bath BA2 7AY (United Kingdom)]. E-mail: f.marken@bath.ac.uk

    2007-06-12

    A film composed of carbon nanoparticles and poly(diallyldimethylammonium chloride) or CNP-PDDAC is formed in a layer-by-layer deposition process at tin-doped indium oxide (ITO) substrates. Excess positive binding sites within this film in aqueous phosphate buffer at pH 9.5 are quantified by adsorption of iron(III)phthalocyanine tetrasulfonate and indigo carmine. Both anionic redox systems bind with Langmuirian characteristics (K {approx} 10{sup 5} mol{sup -1} dm{sup 3}) and show electrochemical reactivity throughout the film at different thicknesses. Therefore, the electrical conductivity in CNP-PDDAC films is good and the positive binding sites are approximately 140 pmol cm{sup -2} per layer. Structural instability of the CNP-PDDAC film in the presence of high concentrations of iron(III)phthalocyanine tetrasulfonate or indigo carmine is observed. Triclosan, a widely used anti-bacterial and anti-fungal agent, exists in aqueous media at pH 9.5 as a negatively charged chlorinated poly-aromatic phenol. Due to the negative charge, triclosan is readily accumulated into CNP-PDDAC films with an efficiency consistent with that expected for simple electrostatic interaction with the cationic binding sites. Oxidation of bound triclosan occurs at 0.6 V versus SCE in a chemically irreversible process. The CNP-PDDAC film electrode is renewed by rinsing in organic solvent and the triclosan oxidation response is shown to correlate with the triclosan concentration in solution from 0.5 to 50 {mu}M. Applications of the CNP-PDDAC film electrode (or improved versions of it) in analysis or in anodic extraction are proposed.

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

    Science.gov (United States)

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

    2006-12-19

    Electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were examined to disclose the effects of partial substitution of Ti atom by the other metals in the composite electrodes. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were prepared by sol-gel process using laurylamine hydrochloride as a template for the formation of micellar precursors yielding well-defined mesoporous nanocrystalline structures, as in the cases of the formation of silica and titania tubules and nanoparticles by the templating mechanism. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were characterized by transmission electron microscopy, BET surface area analysis, X-ray diffraction analysis, Raman spectroscopy, and impedance measurements. The TiO2 anatase nanocrystalline structure is retained after doping a small amount (5 mol %) of Nb, Ge, or Zr into the TiO2 structure, suggesting the homogeneous distribution of the doped metals with replacing Ti atom by the doped metal. The power conversion efficiency of the porphyrin-sensitized solar cells increases in the order Zr-added TiO2 (0.8%) < Nb-added TiO2 (1.2%) < TiO2 (2.0%) < Ge-added TiO2 cells (2.4%) under the same conditions. The improvement of cell performance of the Ge-added TiO2 cell results from the negative shift of the conduction band of the Ge-added TiO2 electrode. The Ge-added TiO2 cell exhibited a maximum power conversion efficiency of 3.5% when the porphyrin was adsorbed onto the surface of the Ge-added TiO2 electrode with a thickness of 4 microm in MeOH for 1 h. PMID:17154633

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

    Science.gov (United States)

    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. PMID:22524013

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

    Science.gov (United States)

    Starr, Christopher A.

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

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

    Science.gov (United States)

    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.

  2. Kinetic lattice Monte Carlo model for oxygen vacancy diffusion in praseodymium doped ceria: Applications to materials design

    International Nuclear Information System (INIS)

    Kinetic lattice Monte Carlo (KLMC) model is developed for investigating oxygen vacancy diffusion in praseodymium-doped ceria. The current approach uses a database of activation energies for oxygen vacancy migration, calculated using first-principles, for various migration pathways in praseodymium-doped ceria. Since the first-principles calculations revealed significant vacancy-vacancy repulsion, we investigate the importance of that effect by conducting simulations with and without a repulsive interaction. Initially, as dopant concentrations increase, vacancy concentration and thus conductivity increases. However, at higher concentrations, vacancies interfere and repel one another, and dopants trap vacancies, creating a 'traffic jam' that decreases conductivity, which is consistent with the experimental findings. The modeled effective activation energy for vacancy migration slightly increased with increasing dopant concentration in qualitative agreement with the experiment. The current methodology comprising a blend of first-principle calculations and KLMC model provides a very powerful fundamental tool for predicting the optimal dopant concentration in ceria related materials. -- graphical abstract: Ionic conductivity in praseodymium doped ceria as a function of dopant concentration calculated using the kinetic lattice Monte Carlo vacancy-repelling model, which predicts the optimal composition for achieving maximum conductivity. Display Omitted Research highlights: → KLMC method calculates the accurate time-dependent diffusion of oxygen vacancies. → KLMC-VR model predicts a dopant concentration of ∼15-20% to be optimal in PDC. → At higher dopant concentration, vacancies interfere and repel one another, and dopants trap vacancies. → Activation energy for vacancy migration increases as a function of dopant content

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

    OpenAIRE

    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 Cu...

  4. Preparation and Numerical Simulation of Ni-SiC Composite Coatings Deposited by Electrode Position

    OpenAIRE

    Huibin Xu; Yong Wang

    2013-01-01

    In order to investigate and predict effects of preparation parameters on wear mass loss of Ni-SiC composite coatings, Ni coatings and Ni-SiC composite coatings were prepared on steel substrates by electrodeposition process. The results showed that the contents of SiC particles increased with density of pulse current and on-duty ratio of pulse current increasing. The predictive curves of wear mass losses predicted by ANN had the similar shapes with the measured curve and the maximum error was ...

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

    Science.gov (United States)

    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.

  6. Preparation and Numerical Simulation of Ni-SiC Composite Coatings Deposited by Electrode Position

    Directory of Open Access Journals (Sweden)

    Huibin Xu

    2013-05-01

    Full Text Available In order to investigate and predict effects of preparation parameters on wear mass loss of Ni-SiC composite coatings, Ni coatings and Ni-SiC composite coatings were prepared on steel substrates by electrodeposition process. The results showed that the contents of SiC particles increased with density of pulse current and on-duty ratio of pulse current increasing. The predictive curves of wear mass losses predicted by ANN had the similar shapes with the measured curve and the maximum error was 9.7%. When the current density was between 30 A/dm2 and 50 A/dm2, the wear losses of Ni coatings and Ni-SiC coatings decreased with the increase of current density. SiC particles in a composite coating electrodeposited by ultrasonic parameters were much greater in number and were dispersed homogeneously in the deposit and the Ni-SiC composite coating exhibited a dense structure.

  7. Application of graphene-ionic liquid-chitosan composite-modified carbon molecular wire electrode for the sensitive determination of adenosine-5′-monophosphate

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Fan [Key Laboratory of Tropical Medicinal Plant Chemistry of Ministry of Education, College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China); Gong, Shixing; Xu, Li; Zhu, Huanhuan [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Sun, Zhenfan [Key Laboratory of Tropical Medicinal Plant Chemistry of Ministry of Education, College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China); Sun, Wei, E-mail: swyy26@hotmail.com [Key Laboratory of Tropical Medicinal Plant Chemistry of Ministry of Education, College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China)

    2013-12-01

    In this paper, a graphene (GR) ionic liquid (IL) 1-octyl-3-methylimidazolium hexafluorophosphate and chitosan composite-modified carbon molecular wire electrode (CMWE) was fabricated by a drop-casting method and further applied to the sensitive electrochemical detection of adenosine-5′-monophosphate (AMP). CMWE was prepared with diphenylacetylene (DPA) as the modifier and the binder. The properties of modified electrode were examined by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical behaviors of AMP was carefully investigated with enhanced responses appeared, which was due to the presence of GR-IL composite on the electrode surface with excellent electrocatalytic ability. A well-defined oxidation peak of AMP appeared at 1.314 V and the electrochemical parameters were calculated by electrochemical methods. Under the selected conditions, the oxidation peak current of AMP was proportional to its concentration in the range from 0.01 μM to 80.0 μM with the detection limit as 3.42 nM (3σ) by differential pulse voltammetry. The proposed method exhibited good selectivity and was applied to the detection of vidarabine monophosphate injection samples with satisfactory results. - Highlights: • A graphene, ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate and chitosan composite were prepared. • Composite-modified carbon molecular wire electrode was fabricated and characterized. • A sensitive electrochemical method for the detection of adenosine-5′-monophosphate was established.

  8. Application of graphene-ionic liquid-chitosan composite-modified carbon molecular wire electrode for the sensitive determination of adenosine-5′-monophosphate

    International Nuclear Information System (INIS)

    In this paper, a graphene (GR) ionic liquid (IL) 1-octyl-3-methylimidazolium hexafluorophosphate and chitosan composite-modified carbon molecular wire electrode (CMWE) was fabricated by a drop-casting method and further applied to the sensitive electrochemical detection of adenosine-5′-monophosphate (AMP). CMWE was prepared with diphenylacetylene (DPA) as the modifier and the binder. The properties of modified electrode were examined by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical behaviors of AMP was carefully investigated with enhanced responses appeared, which was due to the presence of GR-IL composite on the electrode surface with excellent electrocatalytic ability. A well-defined oxidation peak of AMP appeared at 1.314 V and the electrochemical parameters were calculated by electrochemical methods. Under the selected conditions, the oxidation peak current of AMP was proportional to its concentration in the range from 0.01 μM to 80.0 μM with the detection limit as 3.42 nM (3σ) by differential pulse voltammetry. The proposed method exhibited good selectivity and was applied to the detection of vidarabine monophosphate injection samples with satisfactory results. - Highlights: • A graphene, ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate and chitosan composite were prepared. • Composite-modified carbon molecular wire electrode was fabricated and characterized. • A sensitive electrochemical method for the detection of adenosine-5′-monophosphate was established

  9. Electrochemical synthesis and characterization of Gadolinia-Doped Ceria thin films

    International Nuclear Information System (INIS)

    Graphical abstract: Raman spectra and the corresponding microstructures observed by SEM for Gd and Ce-based films. -- Abstract: Cerium oxide based materials are versatile compounds in terms of properties and applications. This work analyses the production of thin layers, of less than 2 μm thick of Gd-doped ceria (GDC) solid solution for high temperature electrochemical applications such as fuel cells and electrolyser cells. We focused on the synthesis of the deposit by cathodic electrodeposition by means of one unique chemical electrolytic bath to produce the doped compound. The resulting deposit is a single phase compound that presents a cubic structure being the expected composition Ce0.77Gd0.23O2-δ. The feasibility of a “one step deposition” (i.e. from one common solution bath) for Gd-doped ceria was demonstrated in the conditions presented in this paper. The presented results deal with the electrodeposition and the microstructural features of the produced materials, which were characterized by X-Ray Diffraction, Scanning Electron Microscopy (FE-SEM) coupled to EDX and Raman spectroscopy

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

    Science.gov (United States)

    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.

  11. A composite electrode based on sub-micrometric iron metal and lithium fluoride

    International Nuclear Information System (INIS)

    In this paper a general method to obtain a mixture of a transition metal embedded in a matrix of lithium fluoride is proposed. The method consists in the reduction of the oxide of the transition metal with lithium hydride to form the correspondent transition metal and lithium oxide. This latter is then converted into lithium fluoride by solid state reaction with ammonium fluoride. In this work the proposed method was applied to iron(III) oxide to obtain a mixture of iron metal and lithium fluoride. The crystal structure and phase purity of the intermediate as well as the final product were analyzed by X-ray diffraction measurement and the crystallite dimensions evaluated by using the Scherrer's formula. The iron metal/lithium fluoride mixture was used as a conversion material and its electrochemical properties evaluated by galvanostatic charge discharge cycles, impedance spectroscopy and galvanostatic intermittent titration technique. As the conversion material is in its reduced state it can be coupled with a carbonaceous negative electrode to build a lithium ion battery, opening new perspectives for using conversion materials in lithium ion batteries technology

  12. A solid-state electrochemiluminescence composite modified electrode based on Ru(bpy)32+/PAHNSA: Characterization and pharmaceutical applications

    International Nuclear Information System (INIS)

    A composite electrochemiluminescence (ECL) sensor was constructed by electrochemical polymerization of 4-amino-3-hydroxynaphthalene sulfonic acid (AHNSA) and tris(2,2′-bipyridyl) ruthenium(II), [Ru(bpy)3]2+, from their aqueous solutions at glassy carbon electrode (GCE). The proposed one-step electrochemical synthesis of the composite film (Ru/PAHNSA/GCE) provides a stable and reactive luminescent for the quantification of chlorpheniramine maleate (CPM) in its pharmaceutical preparations. The properties and the structure of the modified surface were studied using typical voltammetric, Electrochemical Impedance Spectroscopy (EIS), X-Ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM) methods. The intensity of the ECL as a function of [CPM] is linear for the range between 0.2 and 32 μg mL−1 with a detection limit of 0.023 μg mL−1. The performance of the sensor was tested in the presence of interference species and for real sample analysis under optimal conditions

  13. Fabrification of electroreduced graphene oxide–bentonite sodium composite modified electrode and its sensing application for linezolid

    International Nuclear Information System (INIS)

    Graphene and its composites have attracted considerable attention in synthesis and electrochemical applications. In the present work, we have synthesized and characterized graphene oxide-bentonite composite (GO-BEN) and utilized it to fabricate an electrochemical sensor. For this, the solution of GO-BEN cast on glassy carbon electrode (GCE) was reduced electrochemically in phosphate buffer solution of pH 6 to obtain electrochemically reduced graphene oxide-bentonite composite (ERGO-BEN-GCE). This ERGO-BEN film was used for electrochemical investigation of an oxazolidinone class of antibiotic, linezolid (LIN) for the first time. The electrochemical sensor showed excellent enhancement and adsorptive ability towards the electrooxidation of LIN. LIN exhibited two each of oxidation and reduction peaks on ERGO-BEN film in phosphate buffer of pH 7.0. Effects of accumulation time, pH of solution and scan rate were studied and various electrochemical parameters were evaluated. The plot of pH versus Ep gave a slope of 26.2 mV/pH in the pH range of 4.2-8.0 indicating the participation of two electrons and one proton in the electrode process. An adsorptive stripping differential pulse voltammetric method (AdSDPV) was developed for the determination of LIN in bulk, pharmaceutical formulations and urine samples. Adsorptive stripping linear sweep voltammetric (AdSLSV) and differential pulse voltammetric (DPV) methods were also developed and the results were compared. LIN showed linear relationship between the current density and concentration in the range of 0.25 - 31.25 μM with a LOD of 0.0337 μM in AdSDPV method; 0.5 - 31.25 μM with a LOD of 0.100 μM in DPV method and 1.25 - 37.5 μM with a LOD of 0.5461 μM in AdSLSV method respectively. The proposed AdSDPV method was observed to be simple, fast and inexpensive and hence, could be readily adopted for quality control in pharmaceutical products

  14. Understanding RuO{sub 2}.xH{sub 2}O/carbon nanofibre composites as supercapacitor electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Pico, F.; Rojas, R.M.; Amarilla, J.M.; Rojo, J.M. [Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Cientificas (CSIC), Cantoblanco, Sor Juana Ines de la Cruz 3, E-28049 Madrid (Spain); Ibanez, J. [Centro Nacional de Investigaciones Metalurgicas, CSIC, Avda Gregorio del Amo 8, E-28040 Madrid (Spain); Lillo-Rodenas, M.A.; Linares-Solano, A. [MCMA, Departamento de Quimica Inorganica, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain)

    2008-01-21

    Composites made from RuO{sub 2}.xH{sub 2}O particles supported on carbon nanofibres (CNF) have been prepared for supercapacitor electrodes. CNF, produced by Grupo Antolin Ing. SA. using a floating catalyst procedure was treated either in HCl or in HNO{sub 3}. Then the composites were obtained by impregnation of CNF with an aqueous RuCl{sub 3}.0.5H{sub 2}O solution followed by filtering and alkali solution treatment. Heat treatment at 150 C for 2 h was done. Specific capacitance of the composites has been measured and discussed on the basis of their RuO{sub 2}.xH{sub 2}O content and RuO{sub 2}.xH{sub 2}O particle size. The composites having RuO{sub 2}.xH{sub 2}O contents below 11 wt% show RuO{sub 2}.xH{sub 2}O particles, which grow from 2 to 4 nm as the RuO{sub 2}.xH{sub 2}O content increases. The specific capacitance of supported RuO{sub 2}.xH{sub 2}O, which can be very high (up to 840 F g{sup -1}), decreases as the RuO{sub 2}.xH{sub 2}O content increases and RuO{sub 2}.xH{sub 2}O particles grow. The composites having RuO{sub 2}.xH{sub 2}O contents above 11 wt% show RuO{sub 2}.xH{sub 2}O particles of nearly constant size (4 nm); the effect of increasing the RuO{sub 2}.xH{sub 2}O content is to increase the amount of particles but not the size of the particles. In these composites the specific capacitance of supported RuO{sub 2}.xH{sub 2}O is nearly constant (440 F g{sup -1}) and close to bare RuO{sub 2}.xH{sub 2}O (460 F g{sup -1}). (author)

  15. Enhanced Electrocatalytic Performance of a Porous g-C3 N4 /Graphene Composite as a Counter Electrode for Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Wang, Guiqiang; Zhang, Juan; Kuang, Shuai; Zhang, Wei

    2016-08-01

    A porous graphitic carbon nitride (g-C3 N4 )/graphene composite was prepared by a simple hydrothermal method and explored as the counter electrode of dye-sensitized solar cells (DSCs). The obtained g-C3 N4 /graphene composite was characterized by XRD, SEM, TEM, FTIR spectroscopy, and X-ray photoelectron spectroscopy. The results show that incorporating graphene nanosheets into g-C3 N4 forms a three-dimensional architecture with a high surface area, porous structure, efficient electron-transport network, and fast charge-transfer kinetics at the g-C3 N4 /graphene interfaces. These properties result in more electrocatalytic active sites and facilitate electrolyte diffusion and electron transport in the porous framework. As a result, the as-prepared porous g-C3 N4 /graphene composite exhibits an excellent electrocatalytic activity. In I(-) /I3 (-) redox electrolyte, the charge-transfer resistance of the porous g-C3 N4 /graphene composite electrode is 1.8 Ω cm(2) , which is much lower than those of individual g-C3 N4 (70.1 Ω cm(2) ) and graphene (32.4 Ω cm(2) ) electrodes. This enhanced electrocatalytic performance is beneficial for improving the photovoltaic performance of DSCs. By employing the porous g-C3 N4 /graphene composite as the counter electrode, the DSC achieves a conversion efficiency of 7.13 %. This efficiency is comparable to 7.37 % for a cell with a platinum counter electrode. PMID:27381049

  16. A novel high power symmetric ZnO/carbon aerogel composite electrode for electrochemical supercapacitor

    International Nuclear Information System (INIS)

    We present, for the first time, a new material of symmetric electrochemical supercapacitor in which zinc oxide (ZnO) with carbon aerogel (CA) was used as active material. Physical properties of ZnO/CA composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that ZnO has single hexagonal structure and the grain size increases with increase of ZnO compository. The result of cyclic voltammetry indicates that the specific capacitance of ZnO/CA composite in 6 M KOH electrolyte was approximately 25 F/g at 10 mV/s for 2:1 composition. AC impedance analysis reveals that ZnO with carbon aerogel powder enhanced the conductivity by reducing the internal resistance. Galvanostatic charge/discharge measurements were done at various current densities, namely 25, 50, 75, and 100 mA/cm2. It was found that the cells have excellent electrochemical reversibility and capacitive characteristics in KOH electrolyte. The maximum capacitance of the ZnO/CA supercapacitor was 500 F/g at 100 mA/cm2. It has been observed that the specific capacitance is constant up to 500 cycles at all current densities, which implies that the dendrite formation was controlled

  17. Physical, chemical and electrochemical properties of pure and doped ceria

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Sammes, N.M.; Tompsett, G.A.

    2000-01-01

    This paper gives an extract of available data on the physical, chemical, electrochemical and mechanical properties of pure and doped ceria, predominantly in the temperature range from 200 to 1000 degrees C. Several areas are pointed out where further research is needed in order to make a better...

  18. Preparation of activated ceria and its desulfurization performance

    Institute of Scientific and Technical Information of China (English)

    Qing-chun Yu; Yong Deng; Fei Wang; Yue-bin Feng; Xiu-min Chen; Bin Yang; Da-chun Liu

    2015-01-01

    Activated ceria (CeO2/γ-Al2O3) prepared by impregnation was characterized by X-ray diffraction (XRD), scanning electron mi-croscopy (SEM), and hydrogen temperature-programmed reduction (TPR). The desulfurization of the activated ceria was investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TG). The results showed that ceria could be highly dispersed or crystallized on the surface ofγ-alumina. The reduction temperatures of 0.1CeO2/γ-Al2O3, 0.45CeO2/γ-Al2O3, and CeO2 ranged from 250°C to 470°C, 330°C to 550°C, and 350°C to 550°C, respectively. The reduction peak tem-perature of 0.45CeO2/γ-Al2O3 was higher than that of 0.1CeO2/γ-Al2O3, which was consistent with the reduction temperature of CeO2. O2 participated in the reaction between ceria and sulfur dioxide. The desulfurization product was cerium(III) sulfate. The intensity of the hy-droxyl band decreased with the formation of sulfate species.

  19. Adsorption and desorption characteristics of arsenic onto ceria nanoparticles

    Science.gov (United States)

    Feng, Qinzhong; Zhang, Zhiyong; Ma, Yuhui; He, Xiao; Zhao, Yuliang; Chai, Zhifang

    2012-01-01

    The rapid increase in the use of engineered nanoparticles [ENPs] has resulted in an increasing concern over the potential impacts of ENPs on the environmental and human health. ENPs tend to adsorb a large variety of toxic chemicals when they are emitted into the environment, which may enhance the toxicity of ENPs and/or adsorbed chemicals. The study was aimed to investigate the adsorption and desorption behaviors of arsenic on ceria NPs in aqueous solution using batch technique. Results show that the adsorption behavior of arsenic on ceria NPs was strongly dependent on pH and independent of ionic strength, indicating that the electrostatic effect on the adsorption of these elements was relatively not important compared to surface chemical reactions. The adsorption isotherms fitted very well to both the Langmuir and Freundlich models. The thermodynamic parameters (Δ H 0 , Δ S 0 , and Δ G 0 ) for the adsorption of arsenic were determined at three different temperatures of 283, 303, and 323 K. The adsorption reaction was endothermic, and the process of adsorption was favored at high temperature. The desorption data showed that desorption hysteresis occurred at the initial concentration studied. High adsorption capacity of arsenic on ceria NPs suggests that the synergistic effects of ceria NPs and arsenic on the environmental systems may exist when they are released into the environment.

  20. Vanadium oxide–carbon nanotube composite electrodes for energy storage by supercritical fluid deposition: experiment design and device performance

    International Nuclear Information System (INIS)

    Vanadium pentoxide (V2O5) deposited on porous multiwalled carbon nanotube (MWCNT) buckypaper using supercritical fluid CO2(scCO2) deposition shows excellent performance for electrochemical capacitors. However, the low weight loading of V2O5 is one of the main problems. In this paper, design of experiments and response surface methods were employed to explore strategies for improving the active material loading by increasing the organo-vanadium precursor adsorption. A second-order response surface model was fitted to the designed experiments to predict the loading of the vanadium precursors onto carbon nanotube buckypaper as a function of time, temperature and pressure of CO2, buckypaper functionalization, precursor type, initial precursor mass and stir speed. Operation conditions were identified by employing a model that led to a precursor loading of 19.33%, an increase of 72.28% over the initial screening design. CNTs–V2O5 composite electrodes fabricated from deposited samples using the optimized conditions demonstrated outstanding electrochemical performance (947.1 F g−1 of V2O5 at a high scan rate 100 mV s−1). The model also predicted operation conditions under which light precursor aggregation took place. The V2O5 from aggregated precursor still possessed considerable specific capacitance (311 F g−1 of V2O5 at a scan rate 100 mV s−1), and the significantly higher V2O5 loading (∼81%) contributed to an increase in overall electrode capacitance. (paper)

  1. Novel platinum nanoparticles/vapor grown carbon fibers composite counter electrodes for high performance dye sensitized solar cells

    International Nuclear Information System (INIS)

    Highlights: • The Pt nanoparticles (PtNPs) are highly dispersed on vapor grown carbon fibers (VGCFs). • The power conversion efficiency of DSSCs depends substantially on the relative content of VGCFs to PtNPs. • Electrocatalytic activities of PtNPs/VGCFs are examined using impedance, cyclic voltammetry, and Tafel polarization techniques. • Moderate combination of PtNPs and VGCFs exhibits higher power conversion efficiency of DSSCs than that of PtNPs or VGCFs alone. - Abstract: A composite film composed of platinum nanoparticles (PtNPs) and vapor grown carbon fibers (VGCFs) was coated on FTO glass acted as a counter electrode (CE) for high performance dye-sensitized solar cell (DSSC) via a facially thermal approach. The PtNP/VGCF hybrid film was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry (TGA), X-ray diffraction (XRD), Raman, and X-ray photoelectroscopy (XPS). In addition, cyclic voltammetry (CV), Tafel polarization, and electrochemical impedance spectroscopy (EIS) were measured to correlate electrocatalytic activity to photovoltaic performance of DSSCs based on these PtNP/VGCF hybrid counter electrodes (CEs). Results indicated that PtNPs can enhance the thermal stability of VGCFs and were uniformly distributed over VGCFs with high porosity to provide large exposed surface area for redox reactions occurring within the films. VGCFs were found to benefit Pt reduction during annealing at 450 °C. A DSSC comprising the hybrid CE with a weight ratio of PtNPs to VGCFs of 3:7 (PV37) illustrated a higher solar-to-electricity efficiency of 7.77% in comparison to 7.31% for a conventional Pt CE or 3.79% for a pure VGCF CE. Electrochemical analyses demonstrated that PV37 CE featured the strongest electrocatalytic ability for the reduction of I3− to I− and the lowest Nernst diffusion resistance, confirming the highest power conversion efficiency among the samples evaluated

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

    Science.gov (United States)

    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.

  3. Synthesis and characterization of nanostructured electrodes for solid state ionic devices

    Science.gov (United States)

    Zhang, Yuelan

    Solid-state electrochemical energy conversion and storage technologies such as fuel cells and lithium ion batteries will influence the way we use energy and the environment we live in. The demands for advanced power sources with high energy efficiency, minimum environmental impact, and low cost have been the impetus for the development of a new generation of batteries and fuel cells. Currently, lithium ion battery technology's greatest disadvantages are long-term cycling stability and high charge/discharge rate capabilities. On the other hand, fuel cell technology's greatest disadvantage is cost. It is found that these problems could be attenuated by the incorporation of nano-structured materials. But, we are still far away from possessing a solid scientific understanding of what goes on at the nanoscale inside these solid state ionic devices, and what is the relationship between nano-structures and their electrochemical properties, especially between the microstructure and electrode polarization and degradation. Electrode polarization represents a voltage loss in an electrochemical energy conversion process. Such understanding is critical for further progress in solid state ionic devices. This thesis focused on the design, fabrication, and characterization of nanostructured porous electrodes with desired composition and microstructure to minimize electrode polarization losses in the application of fuel cells and lithium ion batteries. Various chemical methods such as sol-gel, hydrothermal, surfactant, colloidal and polymer template-assisted processes have been applied in this work. And various characterization techniques have been used to explore the understanding of the microscopic features with electrochemical interfacial properties of the electrodes. Solid-state diffusion often limits the utilization and rate capability of electrode materials in a lithium-ion battery, especially at high charge/discharge rates. When the fluxes of Li+ insertion or extraction

  4. Direct electrochemistry and electrocatalysis of hemoglobin with carbon nanotube-ionic liquid-chitosan composite materials modified carbon ionic liquid electrode

    International Nuclear Information System (INIS)

    A novel composite biomaterial was prepared by combining chitosan, multi-walled carbon nanotubes (MWCNTs), hemoglobin (Hb) and ionic liquid (IL) 1-butyl-3-methyl-imidazolium bromide together, which was further modified on the surface of a carbon ionic liquid electrode (CILE) with another ionic liquid 1-ethyl-3-methylimidazolium ethylsulphate as the binder. Ultraviolet-visible and Fourier transform infrared spectroscopic results indicated that Hb molecules in the composite film retained the native structure. Cyclic voltammetric results showed that a pair of well-defined redox peaks appeared in 0.1 mol/L phosphate buffer solution, indicating that the direct electron transfer of Hb in the composite film with the underlying electrode was realized. The results were attributed to the synergistic effect of MWCNTs and IL in the composite film, which promoted the electron transfer rate of Hb. The composite material modified electrode showed excellent electrocatalytic ability towards the reduction of different substrates such as trichloroacetic acid and NaNO2 with good stability and reproducibility.

  5. Effect of compounding process on the structure and electrochemical properties of ordered mesoporous carbon/polyaniline composites as electrodes for supercapacitors

    Science.gov (United States)

    Li, Lixia; Song, Huaihe; Zhang, Qincang; Yao, Jingyuan; Chen, Xiaohong

    Polyaniline (PANI) loaded ordered mesoporous carbon (OMC) composites were prepared via different processes, involving the in situ polymerization of aniline in the presence of OMC or its precursor and the direct physical mixing method. On the basis of analyzing the morphologies and structures of these three OMC/PANI composites, the influence of compounding processes on the electrochemical properties as electrodes for supercapacitors was first investigated. It was observed that regardless of compounding process, two distinct electrochemical behaviors took place on all of the composite electrodes, including a redox reaction with insertion and deinsertion of electrolyte ions, and electrostatic attraction at the electrode/electrolyte interface. Additionally, these OMC/PANI composites showed higher specific capacitances compared with pure OMC and PANI. Most significantly, the in situ synthesized OMC/PANI composite using OMC as a starting material exhibited the highest specific capacitance of 747 F g -1 at a current density of 0.1 A g -1 and excellent rate capability, which was attributed to the high degree of dispersion of PANI and the contact of PANI with electrolyte as well as the double fixing effects of surface and mesopore of OMC on PANI.

  6. Effect of compounding process on the structure and electrochemical properties of ordered mesoporous carbon/polyaniline composites as electrodes for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lixia; Song, Huaihe; Zhang, Qincang; Yao, Jingyuan; Chen, Xiaohong [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 100029 Beijing (China)

    2009-02-01

    Polyaniline (PANI) loaded ordered mesoporous carbon (OMC) composites were prepared via different processes, involving the in situ polymerization of aniline in the presence of OMC or its precursor and the direct physical mixing method. On the basis of analyzing the morphologies and structures of these three OMC/PANI composites, the influence of compounding processes on the electrochemical properties as electrodes for supercapacitors was first investigated. It was observed that regardless of compounding process, two distinct electrochemical behaviors took place on all of the composite electrodes, including a redox reaction with insertion and deinsertion of electrolyte ions, and electrostatic attraction at the electrode/electrolyte interface. Additionally, these OMC/PANI composites showed higher specific capacitances compared with pure OMC and PANI. Most significantly, the in situ synthesized OMC/PANI composite using OMC as a starting material exhibited the highest specific capacitance of 747 F g{sup -1} at a current density of 0.1 A g{sup -1} and excellent rate capability, which was attributed to the high degree of dispersion of PANI and the contact of PANI with electrolyte as well as the double fixing effects of surface and mesopore of OMC on PANI. (author)

  7. Electrochemical horseradish peroxidase biosensor based on dextran-ionic liquid-V2O5 nanobelt composite material modified carbon ionic liquid electrode

    International Nuclear Information System (INIS)

    Direct electrochemistry of horseradish peroxidase (HRP) was realized in a dextran (De), 1-ethyl-3-methylimidazolium ethylsulphate ([EMIM]EtOSO3) and V2O5 nanobelt composite material modified carbon ionic liquid electrode (CILE). Spectroscopic results indicated that HRP retained its native structure in the composite. A pair of well-defined redox peaks of HRP appeared in pH 3.0 phosphate buffer solution with the formal potential of -0.213 V (vs. SCE), which was the characteristic of HRP heme Fe(III)/Fe(II) redox couple. The result was attributed to the specific characteristics of De-IL-V2O5 nanocomposite and CILE, which promoted the direct electron transfer rate of HRP with electrode. The electrochemical parameters of HRP on the composite modified electrode were calculated and the electrocatalysis of HRP to the reduction of trichloroacetic acid (TCA) was examined. Under the optimal conditions the reduction peak current increased with TCA concentration in the range from 0.4 to 16.0 mmol L-1. The proposed electrode is valuable for the third-generation electrochemical biosensor.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    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

  10. Potential of Ceria-Based Catalysts for the Oxidation of Landfill Leachate by Heterogeneous Fenton Process

    Directory of Open Access Journals (Sweden)

    E. Aneggi

    2012-01-01

    Full Text Available In this study, ceria and ceria-zirconia solid solutions were tested as catalyst for the treatment of landfill leachate with a Fenton-like process. The catalysts considered in this work were pure ceria and ceria-zirconia solid solutions as well as iron-doped samples. All the catalysts were extensively characterized and applied in batch Fenton-like reactions by a close batch system, the COD (chemical oxygen demand and TOC (total organic carbon parameters were carried out before and after the treatments in order to assay oxidative abatement. Results show a measurable improvement of the TOC and COD abatement using ceria-based catalysts in Fenton-like process and the best result was achieved for iron-doped ceria-zirconia solid solution. Our outcomes point out that heterogeneous Fenton technique could be effectively used for the treatment of landfill leachate and it is worth to be the object of further investigations.

  11. Enhanced direct electron transfer between laccase and hierarchical carbon microfibers/carbon nanotubes composite electrodes. Comparison of three enzyme immobilization methods

    International Nuclear Information System (INIS)

    Three immobilization protocols were investigated with respect to direct electron transfer between hierarchical carbon microfibers/carbon nanotubes composite material on graphite rod electrodes and Trametes hirsuta laccase. Immobilization was done by covalent binding of laccase to aminophenyl-modified electrodes via amide-bond formation with carboxylic acid residues or imino-bond formation with aldehyde groups introduced by oxidation of sugar residues of the enzyme's glycosylation shell. Moreover, immobilization was achieved by adsorbing laccase to electrodes hydrophilized with pyrene-hexanoic acid. High current densities for biocatalytic oxygen reduction were obtained for all immobilization strategies. The formation of the imino bonds let to the binding of laccase in close to 100% direct electron transfer configuration and consequently to the highest oxygen reduction currents.

  12. Two-dimensional electrochemical model for mixed conductors: a study of ceria

    CERN Document Server

    Ciucci, Francesco; Haile, Sossina M; Goodwin, David G

    2009-01-01

    A two-dimensional small bias model has been developed for a patterned metal current collector $|$ mixed oxygen ion and electronic conductor (MIEC) $|$ patterned metal current collector electrochemical cell in a symmetric gas environment. Specifically, we compute the electrochemical potential distributions of oxygen vacancies and electrons in the bulk and near the surface for $\\text{Pt} | \\text{Sm}_{0.15}\\text{Ce}_{0.85}\\text{O}_{1.925} | \\text{Pt}$ symmetric cell in a $\\text{H}_2-\\text{H}_2\\text{O}-\\text{Ar}$ (reducing) atmosphere from 500 to $650^o C$. Using a two-dimensional finite-element model, we show that two types of electronic current exist within the cell: an in-plane drift-diffusion current that flows between the gas $|$ ceria chemical reaction site and the metal current collector, and a cross-plane current that flows between the two metal electrodes on the opposite side of the cell. By fitting the surface reaction constant $\\tilde k_f^0$ to experimental electrode resistance values while fixing mate...

  13. Investigation of the Alkaline Electrochemical Interface and Development of Composite Metal/Metal-Oxides for Hydrogen and Oxygen Electrodes

    Science.gov (United States)

    Bates, Michael

    electrolyte. The HER kinetics of numerous binary & ternary Ni-alloys and composite Ni/metal-oxide/C samples were evaluated in aqueous 0.1 M KOH electrolyte. Furthermore a model of the double layer interface is proposed, which helps explain the observed ensemble effect in the presence of AEI. In Chapter 3, Ni-Fe and Ni-Fe-Co mixed-metal-oxide (MMO) films were investigated for oxygen evolution reaction (OER) activity in 0.1M KOH on high surface area Raney-Nickel supports. During investigations of MMO activity, aniline was identified as a useful "capping agent" for synthesis of high-surface area MMO-polyaniline (PANI) composite materials. A Ni-Fe-Co/PANI-Raney-Ni catalyst was developed which exhibits enhanced mass-activity compared to state-of-the-art Ni-Fe OER electrocatalysts reported to date. The morphology of the MMO catalyst film on PANI/Raney-Ni support provides excellent dispersion of active-sites and should maintain high active-site utilization for catalyst loading on gas-diffusion electrodes. In Chapter 4, the de-activation of reversible-hydrogen electrode catalysts was investigated and the development of a Pt-Ir-Nx/C catalyst is reported, which exhibits significantly increased stability in the HBr/Br 2 electrolyte. In contrast a Pt-Ir/C catalyst exhibited increased tolerance to high-voltage cycling and in particular showed recovery of electrocatalytic activity after reversible de-activation (presumably from bromide adsorption and subsequent oxidative bromide stripping). Under the harshest testing conditions of high-voltage cycling or exposure to Br2 the Pt-based catalyst showed a trend in stability: Pt < Pt-Ir < Pt-Ir-Nx. (Abstract shortened by UMI.).

  14. A Disposable Organophosphorus Pesticides Enzyme Biosensor Based on Magnetic Composite Nano-Particles Modified Screen Printed Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Weigang Wen

    2010-01-01

    Full Text Available A disposable organophosphorus pesticides (OPs enzyme biosensor based on magnetic composite nanoparticle-modified screen printed carbon electrodes (SPCE has been developed. Firstly, an acetylcholinesterase (AChE-coated Fe3O4/Au (GMP magnetic nanoparticulate (GMP-AChE was synthesized. Then, GMP-AChE was absorbed on the surface of a SPCE modified by carbon nanotubes (CNTs/nano-ZrO2/prussian blue (PB/Nafion (Nf composite membrane by an external magnetic field. Thus, the biosensor (SPCE|CNTs/ZrO2/PB/Nf|GMP-AChE for OPs was fabricated. The surface of the biosensor was characterized by scanning electron micrography (SEM and X-ray fluorescence spectrometery (XRFS and its electrochemical properties were studied by cyclic voltammetry (CV and differential pulse voltammetry (DPV. The degree of inhibition (A% of the AChE by OPs was determined by measuring the reduction current of the PB generated by the AChE-catalyzed hydrolysis of acetylthiocholine (ATCh. In pH = 7.5 KNO3 solution, the A was related linearly to the concentration of dimethoate in the range from 1.0 × 10-3–10 ng•mL-1 with a detection limit of 5.6 × 10-4 ng•mL-1. The recovery rates in Chinese cabbage exhibited a range of 88%–105%. The results were consistent with the standard gas chromatography (GC method. Compared with other enzyme biosensors the proposed biosensor exhibited high sensitivity, good selectivity with disposable, low consumption of sample. In particular its surface can be easily renewed by removal of the magnet. The convenient, fast and sensitive voltammetric measurement opens new opportunities for OPs analysis.

  15. Direct Electrochemistry of Glucose Oxidase Immobilized on Chitosan-gold Nanoparticle Composite Film on Glassy Carbon Electrodes and Its Biosensing Application

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The direct electrochemistry of glucose oxidase (Gox) immobilized on a composite matrix based on chitosan (CHIT) and Au nanoparticles (Au NP) underlying on a glassy carbon electrode was achieved. The cyclic voltam-metry and electrochemical impedance spectroscopy were used to characterize the modified electrode. In deaerated buffer solutions, the cyclic voltammetry of the composite films of Gox-Au NP-CHIT showed a pair of well-behaved redox peaks that were assigned to the redox reaction of Gox, confirming the effective immobilization of Gox on the composite film. The electron transfer rate constant was estimated to be 15.6 s-1, indicating a high electron transfer between the Gox redox center and electrode. The combination of CHIT and Au NP also promoted the stability of Gox in the composite film and retained its bioactivity, which might have the potential application to glucose determination. The calculated apparent Michaelis-Menten constant was 10.1 mmol·L-1. Furthermore, the proposed biosensor could be used for the determination of glucose in human plasma samples.

  16. Chitosan mediated synthesis of core/double shell ternary polyaniline/Chitosan/cobalt oxide nano composite-as high energy storage electrode material in supercapacitors

    Science.gov (United States)

    Vellakkat, Mini; Hundekkal, Devendrappa

    2016-01-01

    Nanostructured ternary composite of polyaniline (PANI), Co3O4 nanoparticles, and Chitosan (CS) has been prepared by an in situ chemical oxidation method, and the nanocomposites (CPAESCO) were used as supercapacitor electrodes. The Co3O4 nanoparticles are uniformly coated with CS and PANI layers in it. Different techniques (Fourier transform infrared spectrophotometry, x-ray diffraction, thermal gravimetric analysis, UV-visible spectroscopy, scanning electron microscopy, transmission electron microscopy and electro chemical analysis-cyclic voltammetry, galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy) were used to analyse the optical, structural, thermal, chemical and supercapacitive aspects of the nanocomposites. Core/double shell ternary composite electrode exhibits significantly increased specific capacitance than PANI/Co3O4 or PANI/CS binary composites in supercapacitors. The ternary nanocomposite with 40% nanoparticle exhibits a highest specific capacitance reaching 687 F g-1, Energy density of (95.42 Wh kg-1 at 1 A g-1) and power density of (1549 W kg-1 at 3 A g-1) and outstanding cycling performance, with, 91% capacitance retained over 5000 cycles. It is found that this unique bio compatible nano composite with synergy is a new multifunctional material which will be useful in the design of supercapacitor electrodes and other energy conversion devices too.

  17. Graphite-teflon composite bienzyme electrodes for the determination of cholesterol in reversed micelles. Application to food samples.

    Science.gov (United States)

    Peña, N; Ruiz, G; Reviejo, A J; Pingarrón, J M

    2001-03-15

    A bienzyme amperometric composite biosensor for the determination of free and total cholesterol in food samples is reported. Cholesterol oxidase and horseradish peroxidase, together with potassium ferrocyanide as a mediator, are incorporated into a graphite-70% Teflon matrix. The compatibility of this biosensor design with predominantly nonaqueous media allows the use of reversed micelles as working medium. The reversed micelles are formed with ethyl acetate as continuous phase (in which cholesterol is soluble), a 4% final concentration of 0.05 mol L(-1) phosphate buffer solution, pH 7.4, as dispersed phase, and 0.1 mol L(-1) AOT as emulsifying agent. Studies on the repeatability of the amperometric response obtained at +0.10 V, with and without regeneration of the electrode surface by polishing, on the useful lifetime of one single biosensor and on the reproducibility in the fabrication of different pellets illustrate the robustness of the biosensor design. Determination of free and total cholesterol in food samples such as butter, lard, and egg yoke was carried out, and the obtained results were advantageously compared with those provided by using a commercial Boehringer test kit. PMID:11305650

  18. Structure of vanadium oxide supported on ceria by multi-wavelength Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zili [ORNL; Rondinone, Adam Justin [ORNL; Overbury, Steven {Steve} H [ORNL

    2011-01-01

    ABSTRACT The structure of vanadium oxide species supported on ceria (VOx/CeO2) was investigated under various conditions by in situ multi-wavelength Raman spectroscopy, IR spectroscopy, isotopic labeling and temperature programmed reduction (TPR). For the first time, the detailed structure of dehydrated VOx species was revealed on the polycrystalline ceria support. VOx species can co-exist on ceria surface in the structure of monomer, dimer, trimer, polymer, crystalline V2O5 and CeVO4 as a function of VOx loading. These species interact strongly with both the defect sites and labile surface oxygen of ceria, passivating the redox property of ceria. Under ambient condition, the dispersed VOx species are hydrated into polyvanadate species which can be reversibly dehydrated back to the original structure forms. The ceria support with defect sites facilitates the interaction between water (H218O) and V16Ox species, leading to very facile isotopic oxygen exchange between the two even at room temperature. During H2 reduction, both the VOx species and the ceria support can be reduced with ceria surface being more reducible. The reducibility of various dispersed VOx species scales with their polymerization degree, i.e., polymer > trimer > dimer > monomer. The reoxidation of reduced VOx species is found to proceed via ceria lattice oxygen instead of the gas phase oxygen where ceria acts as an oxygen buffer. The revealed structure evolution of surface VOx species on ceria under hydrated, dehydrated, reduced, and regenerated conditions provides a basis for understanding the vanadia-ceria catalysis.

  19. The effect of Pr co-dopant on the performance of solid oxide fuel cells with Sm-doped ceria electrolyte

    International Nuclear Information System (INIS)

    Samaria-doped ceria Ce0.9Sm0.1O1.95 (SDC) and samaria and praseodymium co-doped ceria Ce0.9Sm0.08Pr0.02O1.95 (SPDC) powders were synthesized by glycine nitrate process. SDC and SPDC electrolytes were made using the corresponding powders to press pellets and sinter them in air at 1400 deg. C. SEM and open porosity measurement showed the electrolytes were not dense and SPDC was more porous than SDC. Raman spectra indicated the oxygen vacancy concentration of SPDC was higher than SDC. Solid oxide fuel cells (SOFCs) with SPDC and SDC electrolytes were made and tested. The SOFC with SPDC electrolyte had higher power density but lower open circuit voltage. Impedance measurement was undertaken for the SOFCs at open circuit and the results showed that both the Ohmic and polarization resistances for SPDC electrolyte are smaller than for SDC. It is explained that co-doping Pr in Sm-doped ceria may increase the oxygen ionic conductivity by changing the grain boundary conditions so that more oxygen vacancies may exist and move faster. The electrochemical catalytic activity of Pr may play an important role in decreasing the polarization of electrolyte-electrode interface of the SOFCs

  20. Bottom electrodes dependence of microstructures and dielectric properties of compositionally graded (Ba1-xSrx)TiO3 thin films

    International Nuclear Information System (INIS)

    Compositionally graded (Ba1-xSrx)TiO3 (BST) thin films, with x decreasing from 0.3 to 0, were deposited on Pt/Ti/SiO2/Si and Ru/SiO2/Si substrates by radio frequency magnetron sputtering technology. The microstructure and dielectric properties of the graded BST thin films were investigated. It was found that the films on Ru electrode have better crystallization, and that RuO2 is present between the Ru bottom electrode and the graded BST thin films by X-ray diffraction and SEM analysis. Dielectric measurement reveals that the graded BST thin films deposited on Ru bottom electrode have higher dielectric constant and tunability. The enhanced dielectric behavior is attributed to better crystallization as well as smaller space charge capacitance width and the formation of RuO2 that is more compatible with the BST films. The graded BST films on Ru electrode show higher leakage current due to lower barrier height and rougher surface of bottom electrode

  1. Sensitive electrochemical determination of trace cadmium on a stannum film/poly(p-aminobenzene sulfonic acid)/electrochemically reduced graphene composite modified electrode

    International Nuclear Information System (INIS)

    In this study, a novel stannum film/poly(p-aminobenzene sulfonic acid)/graphene composite modified glassy carbon electrode (GCE) was prepared by using electrodeposition of exfoliated graphene oxide, electropolymerization of p-aminobenzene sulfonic acid (p-ABSA) and in situ plating stannum fim methods, successively. This sensor was further used for sensitive determination of trace cadmium ions by square wave anodic stripping voltammetry (SWASV). The morphologies and electrochemistry properties of the modified electrode were characterized by scanning electron microscopy, Raman spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy and linear sweep voltammetry. It was found that the formed graphene layer on the top of GCE could remarkably facilitate the electron transfer and enlarge the specific surface area of the electrode. While the poly(p-ABSA) film could effectively increase the adhesion and stability of graphene layer, enhance ion-exchange capacity and prevent the macromolecule in real samples absorbing on the surface of electrode. By combining co-deposits ability with heavy metals of stannum film, the obtained electrode exhibited a good stripping performance for the analysis of Cd(II). Under the optimum conditions, a linear response was observed in the range from 1.0 to 70.0 μgL−1 with a detection limit of 0.05 μgL−1 (S/N = 3). The sensor was further applied to the determination of cadmium ions in real water samples with satisfactory results

  2. Facile synthesis of graphite/PEDOT/MnO2 composites on commercial supercapacitor separator membranes as flexible and high-performance supercapacitor electrodes.

    Science.gov (United States)

    Tang, Pengyi; Han, Lijuan; Zhang, Li

    2014-07-01

    A facile and low-cost method is presented to synthesize graphite/PEDOT/MnO2 composites with controlled network structures on commercial supercapacitor separator (CSS) membranes for high-performance supercapacitors, in which pencil lead and a cellulose-based commercial supercapacitor separator membrane were applied as the graphite source and the flexible substrate, respectively. The dependence of PEDOT and MnO2 loading on the structural formation, the electrochemical performance of the hybrid electrode, and the formation mechanism of MnO2 nanowires are systematically investigated. The optimized electrode possesses a high areal capacitance of 316.4 mF/cm(2) at a scan rate of 10 mV/s and specific capacitance of 195.7 F/g at 0.5 A/g. The asymmetric supercapacitor device assembled using optimized CSS/Graphite/PEDOT/MnO2 electrode and activated carbon electrode exhibits a high energy density of 31.4 Wh/kg at a power density of 90 W/kg and maintains 1 Wh/kg at 4500 W/kg. After 2000 cycles, the device retains 81.1% of initial specific capacitance, and can drive a mini DC-motor for ca. 10 s. The enhanced capability of the CSS-based graphite/PEDOT/MnO2 network electrode has high potential for low-cost, high-performance, and flexible supercapacitors. PMID:24905133

  3. Highly transparent and efficient counter electrode using SiO2/PEDOT-PSS composite for bifacial dye-sensitized solar cells.

    Science.gov (United States)

    Song, Dandan; Li, Meicheng; Li, Yingfeng; Zhao, Xing; Jiang, Bing; Jiang, Yongjian

    2014-05-28

    A highly transparent and efficient counter electrode was facilely fabricated using SiO2/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) inorganic/organic composite and used in bifacial dye-sensitized solar cells (DSCs). The optical properties of SiO2/PEDOT-PSS electrode can be tailored by the blending amount of SiO2 and film thickness, and the incorporation of SiO2 in PEDOT-PSS provides better transmission in the long wavelength range. Meanwhile, the SiO2/PEDOT-PSS counter electrode shows a better electrochemical catalytic activity than PEDOT-PSS electrode for triiodide reduction, and the role of SiO2 in the catalytic process is investigated. The bifacial DSC with SiO2/PEDOT-PSS counter electrode achieves a high power conversion efficiency (PCE) of 4.61% under rear-side irradiation, which is about 83% of that obtained under front-side irradiation. Furthermore, the PCE of bifacial DSC can be significantly increased by adding a reflector to achieve bifacial irradiation, which is 39% higher than that under conventional front-side irradiation. PMID:24802383

  4. Design of an electrolyte composition for stable and rapid charging-discharging of a graphite negative electrode in a bis(fluorosulfonyl)imide-based ionic liquid

    Science.gov (United States)

    Matsui, Yukiko; Yamagata, Masaki; Murakami, Satoshi; Saito, Yasuteru; Higashizaki, Tetsuya; Ishiko, Eriko; Kono, Michiyuki; Ishikawa, Masashi

    2015-04-01

    We evaluate the effects of lithium salt on the charge-discharge performance of a graphite negative electrode in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMImFSI) ionic liquid-based electrolytes. Although the graphite negative electrode exhibits good cyclability and rate capability in both 0.43 mol dm-3 LiFSI/EMImFSI and LiTFSI/EMImFSI (TFSI- = bis(trifluoromethylsulfonyl)imide) at room temperature, only the LiFSI/EMImFSI system enables the graphite electrode to be operated with sufficient discharge capacity at the low temperature of 0 °C, even though there is no noticeable difference in ionic conductivity, compared with LiTFSI/EMImFSI. Furthermore, a clear difference in the low-temperature behaviors of the two cells composed of EMImFSI with a high-concentration of lithium salts is observed. Additionally, charge-discharge operation of the graphite electrode at C-rate of over 5.0 can be achieved using of the high-concentration LiFSI/EMImFSI electrolyte. Considering the low-temperature characteristics in both high-concentration electrolytes, the stable and rapid charge-discharge operation in the high-concentration LiFSI/EMImFSI is presumably attributed to a suitable electrode/electrolyte interface with low resistivity. These results suggest that optimization of the electrolyte composition can realize safe and high-performance lithium-ion batteries that utilize ionic liquid-based electrolytes.

  5. Facile hydrothermal fabrication of nitrogen-doped graphene/Fe{sub 2}O{sub 3} composites as high performance electrode materials for supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Penghui; Li, Weilong, E-mail: lwl@nwu.edu.cn; Wang, Gang; Yu, Baozhi; Li, Xiaojun; Bai, Jintao; Ren, Zhaoyu, E-mail: rzy@nwu.edu.cn

    2014-08-01

    Highlights: • Nitrogen-doped graphene/Fe{sub 2}O{sub 3} composites (NGFeCs) have been synthesized simply. • Fe{sub 2}O{sub 3} particles with size about 20–100 nm were homogenously anchored on NG sheets. • The as-prepared NGFeCs were firstly used as electrode materials for supercapacitor. • The as-prepared NGFeCs electrode shows excellent electrochemical performance. - Abstract: Nitrogen-doped graphene/Fe{sub 2}O{sub 3} composites (NGFeCs) have been synthesized by a simple hydrothermal method. The structure and morphology of the samples were analyzed by X-ray diffraction, Raman spectra, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The results indicate that Fe{sub 2}O{sub 3} particles with size about 20–100 nm were homogenously anchored on nitrogen-doped graphene (NG) sheets. Electrochemical properties of the synthesized materials were characterized by serials of electrochemical measurements in 1 M Na{sub 2}SO{sub 4} electrolyte. The as-prepared NGFeCs show a better electrochemical performance than the graphene/Fe{sub 2}O{sub 3} composites (GFeCs). The specific capacitance of NGFeCs electrode is 260.1 F/g (150.4 F/g for GFeCs electrode) at a current density of 2 A/g. Additionally, over 82.5% (214.6 F/g) of the original capacitance is retained after 1000 cycles at a current density of 2 A/g (61.4% for GFeCs electrode). The superior electrochemical performance can be ascribed to the good electronic conductivity and more active and nucleation sites introduced by the nitrogen-doping (especially by pyrrolic N-doping)

  6. Glucose sensor based on an electrochemical reduced graphene oxide-poly(L-lysine) composite film modified GC electrode.

    Science.gov (United States)

    Hua, Liang; Wu, Xiaqin; Wang, Rong

    2012-12-21

    A convenient and environmentally friendly method of fabricating glucose biosensors is proposed. Glucose oxidase (GOD) was immobilized on electrochemically reduced graphene oxide (ERGO) which was adsorbed on the poly-L-lysine (PLL) modified glassy carbon electrode after being immersed in GO solution for 4 h. The electrochemical behaviors of GOD/ERGO/PLL/GC electrode have been investigated by cyclic voltammetry. Direct electron transfer between GOD immobilized with ERGO/PLL and GC electrode was observed. Moreover, the GOD/ERGO/PLL/GC electrode exhibited excellent electrocatalytic activity for the detection of glucose with a linear range from 0.25 to 5 mmol L(-1). PMID:23082313

  7. Laser assisted modification and chemical metallization of electron-beam deposited ceria thin films

    International Nuclear Information System (INIS)

    Excimer laser processing is applied for tailoring the surface morphology and phase composition of CeO2 ceramic thin films. E-beam evaporation technique is used to deposit samples on stainless steel and silicate glass substrates. The films are then irradiated with ArF* excimer laser pulses under different exposure conditions. Scanning electron microscopy, optical spectrophotometry, X-ray diffractometry and EDS microanalysis are used to characterize the non-irradiated and laser-processed films. Upon UV laser exposure there is large increase of the surface roughness that is accompanied by photo-darkening and ceria reduction. It is shown that the laser induced changes in the CeO2 films facilitate the deposition of metal nano-aggregates in a commercial copper electroless plating bath. The significance of laser modification as a novel approach for the production of CeO2 based thin film catalysts is discussed.

  8. The Sulphur Poisoning Behaviour of Gadolinia Doped Ceria Model Systems in Reducing Atmospheres

    Directory of Open Access Journals (Sweden)

    Matthias Gerstl

    2016-08-01

    Full Text Available An array of analytical methods including surface area determination by gas adsorption using the Brunauer, Emmett, Teller (BET method, combustion analysis, XRD, ToF-SIMS, TEM and impedance spectroscopy has been used to investigate the interaction of gadolinia doped ceria (GDC with hydrogen sulphide containing reducing atmospheres. It is shown that sulphur is incorporated into the GDC bulk and might lead to phase changes. Additionally, high concentrations of silicon are found on the surface of model composite microelectrodes. Based on these data, a model is proposed to explain the multi-facetted electrochemical degradation behaviour encountered during long term electrochemical measurements. While electrochemical bulk properties of GDC stay largely unaffected, the surface polarisation resistance is dramatically changed, due to silicon segregation and reaction with adsorbed sulphur.

  9. Effect of Gd dopant concentration on the defect engineering in ceria nanostructures

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted Highlights: ► Investigates the ionic conductivity of defect engineered Gd doped nano scale ceria. ► Reveals that there exists an optimum concentration of dopant to engineer ceria with large O2 vacancies. ► For the first time the Nanosponge morphology observed in the Gd doped nanoceria. ► It is observed that 5% of Gd in ceria is optimum to induce appropriate amount of defects. ► Thereby an enhanced ionic conductivity is achieved in 5% Gd doped ceria. -- Abstract: In this study, the fabrication and characterization of pure and gadolinium (Gd) doped ceria nanostructures (Ce1−xGdxO2−δ where x = 0.05, 0.1 and 0.2) are investigated. The origin of defect formation has been systematically investigated by XRD and UV-Visible Raman. All the fabricated ceria are found to be “Nanosponge” morphology which is observed by using FESEM technique. The charge transfer of O2− ions and Ce3+/Ce4+ in the ceria host due to these defect structures are studied by UV–DRS. Impedance analysis is showed an enhanced ionic conductivity for 5% Gd doped ceria compared to other concentration of Gd, revealing that the dopant concentration is a critical parameter in engineering a large number of vacancy defects in ceria nanostructures.

  10. Brain microvascular endothelial cell association and distribution of a 5 nm ceria engineered nanomaterial

    Directory of Open Access Journals (Sweden)

    Dan M

    2012-07-01

    Full Text Available Mo Dan,1,2 Michael T Tseng,3 Peng Wu,4 Jason M Unrine,5 Eric A Grulke,4 Robert A Yokel1,21Department of Pharmaceutical Sciences, College of Pharmacy, 2Graduate Center for Toxicology, University of Kentucky, Lexington, KY, USA; 3Departments of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY, USA; 4Chemical and Materials Engineering Department, 5Department of Plant and Soil Science, University of Kentucky, Lexington, KY, USAPurpose: Ceria engineered nanomaterials (ENMs have current commercial applications and both neuroprotective and toxic effects. Our hypothesis is that ceria ENMs can associate with brain capillary cells and/or cross the blood–brain barrier.Methods: An aqueous dispersion of ~5 nm ceria ENM was synthesized and characterized in house. Its uptake space in the Sprague Dawley rat brain was determined using the in situ brain perfusion technique at 15 and 20 mL/minute flow rates; 30, 100, and 500 µg/mL ceria perfused for 120 seconds at 20 mL/minute; and 30 µg/mL perfused for 20, 60, and 120 seconds at 20 mL/minute. The capillary depletion method and light and electron microscopy were used to determine its capillary cell and brain parenchymal association and localization.Results: The vascular space was not significantly affected by brain perfusion flow rate or ENM, demonstrating that this ceria ENM did not influence blood–brain barrier integrity. Cerium concentrations, determined by inductively coupled plasma mass spectrometry, were significantly higher in the choroid plexus than in eight brain regions in the 100 and 500 µg/mL ceria perfusion groups. Ceria uptake into the eight brain regions was similar after 120-second perfusion of 30, 100, and 500 µg ceria/mL. Ceria uptake space significantly increased in the eight brain regions and choroid plexus after 60 versus 20 seconds, and it was similar after 60 and 120 seconds. The capillary depletion method showed 99.4% ± 1.1% of the ceria ENM associated

  11. Disinfection effects of undoped and silver-doped ceria powders of nanometer crystallite size

    Science.gov (United States)

    Tsai, Dah-Shyang; Yang, Tzu-Sen; Huang, Yu-Sheng; Peng, Pei-Wen; Ou, Keng-Liang

    2016-01-01

    Being endowed with an ability of capturing and releasing oxygen, the ceria surface conventionally assumes the role of catalyzing redox reactions in chemistry. This catalytic effect also makes possible its cytotoxicity toward microorganisms at room temperature. To study this cytotoxicity, we synthesized the doped and undoped ceria particles of 8–9 nm in size using an inexpensive precipitation method and evaluated their disinfecting aptitudes with the turbidimetric and plate count methods. Among the samples being analyzed, the silver-doped ceria exhibits the highest sterilization ability, yet the undoped ceria is the most intriguing. The disinfection effect of undoped ceria is moderate in magnitude, demanding a physical contact between the ceria surface and bacteria cell wall, or the redox catalysis that can damage the cell wall and result in the cell killing. Evidently, this effect is short-range and depends strongly on dispersion of the nanoparticles. In contrast, the disinfection effects of silver-doped ceria reach out several millimeters since it releases silver ions to poison the surrounding microorganisms. Additionally, the aliovalent silver substitution creates more ceria defects. The synergetic combination, silver poisoning and heterogeneous redox catalysis, lifts and extends the disinfecting capability of silver-doped ceria to a superior level. PMID:27330294

  12. Composition and evolution of the solid-electrolyte interphase in Na2Ti3O7 electrodes for Na-ion batteries: XPS and Auger parameter analysis.

    Science.gov (United States)

    Muñoz-Márquez, Miguel A; Zarrabeitia, Maider; Castillo-Martínez, Elizabeth; Eguía-Barrio, Aitor; Rojo, Teófilo; Casas-Cabanas, Montse

    2015-04-15

    Na2Ti3O7 is considered a promising negative electrode for Na-ion batteries; however, poor capacity retention has been reported and the stability of the solid-electrolyte interphase (SEI) could be one of the main actors of this underperformance. The composition and evolution of the SEI in Na2Ti3O7 electrodes is hereby studied by means of X-ray photoelectron spectroscopy (XPS). To overcome typical XPS limitations in the photoelectron energy assignments, the analysis of the Auger parameter is here proposed for the first time in battery materials characterization. We have found that the electrode/electrolyte interface formed upon discharge, mostly composed by carbonates and semicarbonates (Na2CO3, NaCO3R), fluorides (NaF), chlorides (NaCl) and poly(ethylene oxide)s, is unstable upon electrochemical cycling. Additionally, solid state nuclear magnetic resonance (NMR) studies prove the reaction of the polyvinylidene difluoride (PVdF) binder with sodium. The powerful approach used in this work, namely Auger parameter study, enables us to correctly determine the composition of the electrode surface layer without any interference from surface charging or absolute binding energy calibration effects. As a result, the suitability for Na-ion batteries of binders and electrolytes widely used for Li-ion batteries is questioned here. PMID:25811538

  13. Electrospark deposition of Al2O3–TiB2/Ni composite-phase surface coatings on Cu–Cr–Zr alloy electrodes

    Directory of Open Access Journals (Sweden)

    Ping Luo

    2015-03-01

    Full Text Available To improve electrode life during the resistance spot welding of galvanized steel plates, an Al2O3–TiB2 composite coating was synthesized on the surfaces of spot-welding electrodes through an electrospark deposition process. The microstructure, elemental composition, phase structure, and mechanical properties of the coating were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, and microhardness testing. It was found that extensive cracking occurred in the monolithic Al2O3–TiB2 coating and at the coating–electrode interface. When the Al2O3–TiB2 coating was deposited on electrodes precoated with Ni, the number of defects decreased significantly. Further, delamination did not occur, and fewer cracks were formed. The average hardness of the multilayered Al2O3–TiB2/Ni coating was approximately 2200 HV and higher than that of the monolithic Al2O3–TiB2 coating (1100 HV.

  14. Room-temperature solution-processed and metal oxide-free nano-composite for the flexible transparent bottom electrode of perovskite solar cells.

    Science.gov (United States)

    Lu, Haifei; Sun, Jingsong; Zhang, Hong; Lu, Shunmian; Choy, Wallace C H

    2016-03-21

    The exploration of low-temperature and solution-processed charge transporting and collecting layers can promote the development of low-cost and large-scale perovskite solar cells (PVSCs) through an all solution process. Here, we propose a room-temperature solution-processed and metal oxide-free nano-composite composed of a silver nano-network and graphene oxide (GO) flawless film for the transparent bottom electrode of a PVSC. Our experimental results show that the amount of GO flakes play a critical role in forming the flawless anti-corrosive barrier in the silver nano-network through a self-assembly approach under ambient atmosphere, which can effectively prevent the penetration of liquid or gaseous halides and their corrosion against the silver nano-network underneath. Importantly, we simultaneously achieve good work function alignment and surface wetting properties for a practical bottom electrode by controlling the degree of reduction of GO flakes. Finally, flexible PVSC adopting the room-temperature and solution-processed nano-composite as the flexible transparent bottom electrode has been demonstrated on a polyethylene terephthalate (PET) substrate. As a consequence, the demonstration of our room-temperature solution-processed and metal oxide-free flexible transparent bottom electrode will contribute to the emerging large-area flexible PVSC technologies. PMID:26923479

  15. Enhanced direct electron transfer reactivity of hemoglobin in cationic gemini surfactant-room temperature ionic liquid composite film on glassy carbon electrodes

    International Nuclear Information System (INIS)

    A novel composite film comprising cationic gemini surfactant butyl-α,ω-bis(dimethylcetylammonium bromide) (C16H33N(CH3)2-C4H8-N(CH3)2C16H33, C16-C4-C16) and ionic liquid 1-octyl-3-methylimidazolium hexafluorophate (OMIMPF6) has been prepared. The composite film shows good biocompatibility and it can promote the direct electron transfer between hemoglobin (Hb) and glassy carbon (GC) electrode. On the C16-C4-C16 (dissolved in ethanol)-OMIMPF6 film coated GC electrode, the immobilized Hb can exhibit a pair of well-defined, quasi-reversible and stable redox peaks with a formal potential of -0.317 V (vs SCE) in 0.10 M pH 7 phosphate buffer solutions. The electron transfer coefficient (α) of Hb is calculated to be 0.44 and the heterogeneous electron transfer rate constant is 6.08 s-1. With the length of alkyl chains of gemini surfactant increasing and the ethanol concentration rising, the redox peaks of the resulting electrode C16-C4-C16-OMIMPF6-Hb/GC become bigger. The electrode presents good electrocatalytic response to peroxide hydrogen. The kinetic parameters Imax and km for the catalytic reaction are estimated. In addition, UV-vis spectra and reflectance absorption infrared spectra demonstrate that the Hb immobilized in the C16-C4-C16-OMIMPF6 film almost retains the structure of native Hb

  16. Mechanical characterization of hydroxyapatite, thermoelectric materials and doped ceria

    Science.gov (United States)

    Fan, Xiaofeng

    For a variety of applications of brittle ceramic materials, porosity plays a critical role structurally and/or functionally, such as in engineered bone scaffolds, thermoelectric materials and in solid oxide fuel cells. The presence of porosity will affect the mechanical properties, which are essential to the design and application of porous brittle materials. In this study, the mechanical property versus microstructure relations for bioceramics, thermoelectric (TE) materials and solid oxide fuel cells were investigated. For the bioceramic material hydroxyapatite (HA), the Young's modulus was measured using resonant ultrasound spectroscopy (RUS) as a function of (i) porosity and (ii) microcracking damage state. The fracture strength was measured as a function of porosity using biaxial flexure testing, and the distribution of the fracture strength was studied by Weibull analysis. For the natural mineral tetrahedrite based solid solution thermoelectric material (Cu10Zn2As4S13 - Cu 12Sb4S13), the elastic moduli, hardness and fracture toughness were studied as a function of (i) composition and (ii) ball milling time. For ZiNiSn, a thermoelectric half-Heusler compound, the elastic modulus---porosity and hardness---porosity relations were examined. For the solid oxide fuel cell material, gadolina doped ceria (GDC), the elastic moduli including Young's modulus, shear modulus, bulk modulus and Poisson's ratio were measured by RUS as a function of porosity. The hardness was evaluated by Vickers indentation technique as a function of porosity. The results of the mechanical property versus microstructure relations obtained in this study are of great importance for the design and fabrication of reliable components with service life and a safety factor. The Weibull modulus, which is a measure of the scatter in fracture strength, is the gauge of the mechanical reliability. The elastic moduli and Poisson's ratio are needed in analytical or numerical models of the thermal and

  17. A composite catalytic film of Ni-NPs/PEDOT: PSS for the counter electrodes in dye–sensitized solar cells

    International Nuclear Information System (INIS)

    Graphical abstract: The POEM-dispersed Ni-NPs were incorporated with PEDOT:PSS as the electro-catalytic composite film for the CE of a DSSC. The η of the DSSC using Ni-NPs/PEDOT:PSS CE (7.81%) is better than that of the cell with a Pt CE (7.63%). The Ni-NPs/PEDOT:PSS CE showed an unfailing stability after long-term potential cycling. - Highlights: • POEM was synthesized for the good dispersion of the Ni-NPs. • PEDOT:PSS was intended to enable a good contact between the Ni-NPs and the substrate. • Ni-NPs was used to improve the conductivity of PEDOT:PSS film. • The η of the DSSC with Ni-NPs/PEDOT:PSS (7.81%) was higher than that of the cell with Pt (7.63%). • The Ni-NPs/PEDOT:PSS CE showed a high stability after long-term potential cycling. - Abstract: As the catalytic material for the counter electrode (CE) of a dye-sensitized solar cell (DSSC), a composite film of nickel nanoparticles (Ni-NPs) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was deposited on an FTO glass substrate, by using a home-made polymeric dispersant, poly(oxyethylene)-segmented imide (POEM). Scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive X-ray spectroscopy (EDX) were used to characterize the films. A solar-to-electricity conversion efficiency (η) of 7.81% was achieved for the DSSC using Ni-NPs/PEDOT: PSS, while the DSSC with the Pt CE showed a ηof 7.63%. The best composite film showed a high stability, when it was subjected to potential cycling for 100 cycles in an electrolyte containing the redox couple, iodide/triiodide (I-/I3−), while the Pt film showed a considerable decrease in its stability. In replacing the conventional sputtered Pt film as the CE in a DSSC, the Ni-NPs/PEDOT: PSS film exhibited multiple advantages of higher power conversion efficiency, higher stability of the catalytic film, and less expensive material cost. The photovoltaic parameters of the cells were substantiated by incident photon

  18. Differential pulse voltammetric determination of ascorbic acid in the presence of folic acid at electro-deposited NiO/graphene composite film modified electrode

    International Nuclear Information System (INIS)

    This paper demonstrated an electrochemical sensor based on NiO nanoparticles-graphene composite film (NiO/GR) modified glassy carbon electrode for detecting ascorbic acid (AA) in the presence of folic acid using differential pulse voltammetry. The obtained NiO/GR nanocomposite was fabricated by electro-deposition technology. The morphologies and interface properties of NiO/GR composite film were examined by scanning electron microscopy, energy dispersive X-ray spectroscopy and electrochemical impedance spectroscopy. The modified electrode exhibits excellent sensing performance for detecting AA with linear range from 0.05 to 1100 μM and a detection limit of 0.0167 μM (S/N = 3). Under optimal conditions, the sensor displays excellent stability and satisfactory results in real samples analysis

  19. Zinc deposition and dissolution in methanesulfonic acid onto a carbon composite electrode as the negative electrode reactions in a hybrid redox flow battery

    International Nuclear Information System (INIS)

    Highlights: → Use methanesulfonic acid to avoid dendrite formation during a long (>4 h) zinc electrodeposition. → Electrochemical characterization of Zn(II) deposition and its morphology using methanesulfonic acid solutions. → Use of additives to improve the efficiency of zinc deposition and dissolution as the half cell reaction of a redox flow battery. - Abstract: Electrodeposition and dissolution of zinc in methanesulfonic acid were studied as the negative electrode reactions in a hybrid redox flow battery. Cyclic voltammetry at a rotating disk electrode was used to characterize the electrochemistry and the effect of process conditions on the deposition and dissolution rate of zinc in aqueous methanesulfonic acid. At a sufficiently high current density, the deposition process became a mass transport controlled reaction. The diffusion coefficient of Zn2+ ions was 7.5 x 10-6 cm2 s-1. The performance of the zinc negative electrode in a parallel plate flow cell was also studied as a function of Zn2+ ion concentration, methanesulfonic acid concentration, current density, electrolyte flow rate, operating temperature and the addition of electrolytic additives, including potassium sodium tartarate, tetrabutylammonium hydroxide, and indium oxide. The current-, voltage- and energy efficiencies of the zinc-half cell reaction and the morphologies of the zinc deposits are also discussed. The energy efficiency improved from 62% in the absence of additives to 73% upon the addition of 2 x 10-3 mol dm-3 of indium oxide as a hydrogen suppressant. In aqueous methanesulfonic acid with or without additives, there was no significant dendrite formation after zinc electrodeposition for 4 h at 50 mA cm-2.

  20. Effects of Electrodeposition Mode and Deposition Cycle on the Electrochemical Performance of MnO2-NiO Composite Electrodes for High-Energy-Density Supercapacitors

    OpenAIRE

    Rusi; S. R. Majid

    2016-01-01

    Nanostructured network-like MnO2-NiO composite electrodes were electrodeposited onto stainless steel substrates via different electrodeposition modes, such as chronopotentiometry, chronoamperometry, and cyclic voltammetry, and then subjected to heat treatment at 300°C for metal oxide conversion. X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy were used to study the crystalline natures and morphologies of the deposited films. The electrochem...

  1. Electrochemical reactivity and proton transport mechanisms in nanostructured ceria

    Science.gov (United States)

    Ding, J.; Strelcov, E.; Kalinin, S. V.; Bassiri-Gharb, N.

    2016-08-01

    Electrochemical reactivity and ionic transport at the nanoscale are essential in many energy applications. In this study, time-resolved Kelvin probe force microscopy (tr-KPFM) is utilized for surface potential mapping of nanostructured ceria, in both space and time domains. The fundamental mechanisms of proton injection and transport are studied as a function of environmental conditions and the presence or absence of triple phase boundaries. Finite element modeling is used to extract physical parameters from the experimental data, allowing not only quantification of the observed processes, but also decoupling of their contributions to the measured signal. The constructed phase diagrams of the parameters demonstrate a thermally activated proton injection reaction at the triple phase boundary, and two transport processes that are responsible for the low-temperature proton conductivity of nanostructured ceria.

  2. Electrochemical reactivity and proton transport mechanisms in nanostructured ceria.

    Science.gov (United States)

    Ding, J; Strelcov, E; Kalinin, S V; Bassiri-Gharb, N

    2016-08-26

    Electrochemical reactivity and ionic transport at the nanoscale are essential in many energy applications. In this study, time-resolved Kelvin probe force microscopy (tr-KPFM) is utilized for surface potential mapping of nanostructured ceria, in both space and time domains. The fundamental mechanisms of proton injection and transport are studied as a function of environmental conditions and the presence or absence of triple phase boundaries. Finite element modeling is used to extract physical parameters from the experimental data, allowing not only quantification of the observed processes, but also decoupling of their contributions to the measured signal. The constructed phase diagrams of the parameters demonstrate a thermally activated proton injection reaction at the triple phase boundary, and two transport processes that are responsible for the low-temperature proton conductivity of nanostructured ceria. PMID:27407076

  3. Effects of Electrodeposition Mode and Deposition Cycle on the Electrochemical Performance of MnO2-NiO Composite Electrodes for High-Energy-Density Supercapacitors

    Science.gov (United States)

    Rusi; Majid, S. R.

    2016-01-01

    Nanostructured network-like MnO2-NiO composite electrodes were electrodeposited onto stainless steel substrates via different electrodeposition modes, such as chronopotentiometry, chronoamperometry, and cyclic voltammetry, and then subjected to heat treatment at 300°C for metal oxide conversion. X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy were used to study the crystalline natures and morphologies of the deposited films. The electrochemical properties were investigated using cyclic voltammetry and charge/discharge tests. The results revealed that the electrochemical performance of the as-obtained composite electrodes depended on the electrodeposition mode. The electrochemical properties of MnO2-NiO composite electrodes prepared using cyclic voltammetry exhibited the highest capacitance values and were most influenced by the deposition cycle number. The optimum specific capacitance was 3509 Fg−1 with energy and power densities of 1322 Wh kg−1 and 110.5 kW kg−1, respectively, at a current density of 20 Ag−1 in a mixed KOH/K3Fe(CN)6 electrolyte. PMID:27182595

  4. Sensitive voltammetric determination of chloramphenicol by using single-wall carbon nanotube-gold nanoparticle-ionic liquid composite film modified glassy carbon electrodes

    International Nuclear Information System (INIS)

    A novel composite film modified glassy carbon electrode has been fabricated and characterized by scanning electron microscope (SEM) and voltammetry. The composite film comprises of single-wall carbon nanotube (SWNT), gold nanoparticle (GNP) and ionic liquid (i.e. 1-octyl-3-methylimidazolium hexafluorophosphate), thus has the characteristics of them. The resulting electrode shows good stability, high accumulation efficiency and strong promotion to electron transfer. On it, chloramphenicol can produce a sensitive cathodic peak at -0.66 V (versus SCE) in pH 7.0 phosphate buffer solutions. Parameters influencing the voltammetric response of chloramphenicol are optimized, which include the composition of the film and the operation conditions. Under the optimized conditions, the peak current is linear to chloramphenicol concentration in the range of 1.0 x 10-8-6.0 x 10-6 M, and the detection limit is estimated to be 5.0 x 10-9 M after an accumulation for 150 s on open circuit. The electrode is applied to the determination of chloramphenicol in milk samples, and the recoveries for the standards added are 97.0% and 100.3%. In addition, the electrochemical reaction of chloramphenicol and the effect of single-wall carbon nanotube, gold nanoparticle and ionic liquid are discussed

  5. Hydrogen peroxide biosensor based on gold nanoparticles/thionine/gold nanoparticles/multi-walled carbon nanotubes-chitosans composite film-modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Li Shenfeng; Zhu Xiaoying; Zhang Wei; Xie Guoming [Key Laboratory of Laboratory Medical Diagnostics, Ministry of Education, Department of Laboratory Medicine, Chongqing Medical University, Chongqing 400016 (China); Feng Wenli, E-mail: fengwlcqmu@sina.com [Key Laboratory of Laboratory Medical Diagnostics, Ministry of Education, Department of Laboratory Medicine, Chongqing Medical University, Chongqing 400016 (China)

    2012-01-15

    In this paper, an amperometric electrochemical biosensor for the detection of hydrogen peroxide (H{sub 2}O{sub 2}), based on gold nanoparticles (GNPs)/thionine (Thi)/GNPs/multi-walled carbon nanotubes (MWCNTs)-chitosans (Chits) composite film was developed. MWCNTs-Chits homogeneous composite was first dispersed in acetic acid solution and then the GNPs were in situ synthesized at the composite. The mixture was dripped on the glassy carbon electrode (GCE) and then the Thi was deposited by electropolymerization by Au-S or Au-N covalent bond effect and electrostatic adsorption effect as an electron transfer mediator. Finally, the mixture of GNPs and horseradish peroxidase (HRP) was assembled onto the modified electrode by covalent bond. The electrochemical behavior of the modified electrode was investigated by scanning electron microscope, cyclic voltammetry and chronoamperometry. This study introduces the in situ-synthesized GNPs on the other surface of the modified materials in H{sub 2}O{sub 2} detection. The linear response range of the biosensor to H{sub 2}O{sub 2} concentration was from 5 Multiplication-Sign 10{sup -7} mol L{sup -1} to 1.5 Multiplication-Sign 10{sup -3} mol L{sup -1} with a detection limit of 3.75 Multiplication-Sign 10{sup -8} mol L{sup -1} (based on S/N = 3).

  6. High Energy Density All Solid State Asymmetric Pseudocapacitors Based on Free Standing Reduced Graphene Oxide-Co3O4 Composite Aerogel Electrodes.

    Science.gov (United States)

    Ghosh, Debasis; Lim, Joonwon; Narayan, Rekha; Kim, Sang Ouk

    2016-08-31

    Modern flexible consumer electronics require efficient energy storage devices with flexible free-standing electrodes. We report a simple and cost-effective route to a graphene-based composite aerogel encapsulating metal oxide nanoparticles for high energy density, free-standing, binder-free flexible pseudocapacitive electrodes. Hydrothermally synthesized Co3O4 nanoparticles are successfully housed inside the microporous graphene aerogel network during the room temperature interfacial gelation at the Zn surface. The resultant three-dimensional (3D) rGO-Co3O4 composite aerogel shows mesoporous quasiparallel layer stack morphology with a high loading of Co3O4, which offers numerous channels for ion transport and a 3D interconnected network for high electrical conductivity. All solid state asymmetric pseudocapacitors employing the composite aerogel electrodes have demonstrated high areal energy density of 35.92 μWh/cm(2) and power density of 17.79 mW/cm(2) accompanied by excellent cycle life. PMID:27494271

  7. 复合电极用导电树脂的制备%PREPARATION OF ELECTRO-CONDUCTIVE RESIN USED AS COMPOSITE ELECTRODE

    Institute of Scientific and Technical Information of China (English)

    刘俊宁; 傅春华

    2011-01-01

    Electro-conductive resin used as water-treated composite electrode was prepared by using low-mederate temperature curing agent(8104), E- 51 epoxy resin, and electroconductive graphite. The electro-conductive resin was diluted by inert diluents and then sprayed to a steel plate by spraying process. The composite electrode was prepared by curing at 80℃. The test results showed that the electro-conductive resin had good conductivity, acid and alkali resistance and adhesion properties, and met well the use requirements of water-treated composite electrode.%采用次中温环氧树脂(EP)固化剂(8104)、E-51 EP、导电石墨制备了水处理复合电极用导电树脂,树脂经惰性稀释剂稀释后,采用喷涂工艺把导电树脂喷附在钢板上,经80℃固化后,制造出复合电极.试验结果表明,导电树脂具有较好的导电性、耐酸碱性能和粘接性能,很好满足了水处理复合电极的使用要求.

  8. Effects of Electrodeposition Mode and Deposition Cycle on the Electrochemical Performance of MnO2-NiO Composite Electrodes for High-Energy-Density Supercapacitors.

    Science.gov (United States)

    Rusi; Majid, S R

    2016-01-01

    Nanostructured network-like MnO2-NiO composite electrodes were electrodeposited onto stainless steel substrates via different electrodeposition modes, such as chronopotentiometry, chronoamperometry, and cyclic voltammetry, and then subjected to heat treatment at 300°C for metal oxide conversion. X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy were used to study the crystalline natures and morphologies of the deposited films. The electrochemical properties were investigated using cyclic voltammetry and charge/discharge tests. The results revealed that the electrochemical performance of the as-obtained composite electrodes depended on the electrodeposition mode. The electrochemical properties of MnO2-NiO composite electrodes prepared using cyclic voltammetry exhibited the highest capacitance values and were most influenced by the deposition cycle number. The optimum specific capacitance was 3509 Fg-1 with energy and power densities of 1322 Wh kg-1 and 110.5 kW kg-1, respectively, at a current density of 20 Ag-1 in a mixed KOH/K3Fe(CN)6 electrolyte. PMID:27182595

  9. Effects of Electrodeposition Mode and Deposition Cycle on the Electrochemical Performance of MnO2-NiO Composite Electrodes for High-Energy-Density Supercapacitors.

    Directory of Open Access Journals (Sweden)

    Rusi

    Full Text Available Nanostructured network-like MnO2-NiO composite electrodes were electrodeposited onto stainless steel substrates via different electrodeposition modes, such as chronopotentiometry, chronoamperometry, and cyclic voltammetry, and then subjected to heat treatment at 300°C for metal oxide conversion. X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy were used to study the crystalline natures and morphologies of the deposited films. The electrochemical properties were investigated using cyclic voltammetry and charge/discharge tests. The results revealed that the electrochemical performance of the as-obtained composite electrodes depended on the electrodeposition mode. The electrochemical properties of MnO2-NiO composite electrodes prepared using cyclic voltammetry exhibited the highest capacitance values and were most influenced by the deposition cycle number. The optimum specific capacitance was 3509 Fg-1 with energy and power densities of 1322 Wh kg-1 and 110.5 kW kg-1, respectively, at a current density of 20 Ag-1 in a mixed KOH/K3Fe(CN6 electrolyte.

  10. Driving High-Performance n- and p-type Organic Transistors with Carbon Nanotube/Conjugated Polymer Composite Electrodes Patterned Directly from Solution

    KAUST Repository

    Hellstrom, Sondra L.

    2010-07-12

    We report patterned deposition of carbon nanotube/conjugated polymer composites from solution with high nanotube densities and excellent feature resolution. Such composites are suited for use as electrodes in high-performance transistors of pentacene and C60, with bottom-contact mobilities of ?0.5 and ?1 cm2 V-1 s-1, respectively. This represents a clear step towards development of inexpensive, high-performance all-organic circuits. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Soot Combustion over Nanostructured Ceria with Different Morphologies

    Science.gov (United States)

    Zhang, Wen; Niu, Xiaoyu; Chen, Liqiang; Yuan, Fulong; Zhu, Yujun

    2016-01-01

    In this study, nano-structure ceria with three different morphologies (nanorod, nanoparticle and flake) have been prepared by hydrothermal and solvothermal methods. The ceria samples were deeply characterized by XRD, SEM, TEM, H2-TPR, XPS and in-situ DRIFTS, and tested for soot combustion in absence/presence NO atmospheres under loose and tight contact conditions. The prepared ceria samples exhibit excellent catalytic activities, especially, the CeO2 with nanorod (Ce-R) shows the best catalytic activity, for which the peak temperature of soot combustion (Tm) is about 500 and 368 °C in loose and tight contact conditions, respectively. The catalytic activity for Ce-R is higher than that of the reported CeO2 catalysts and reaches a level that of precious metals. The characterization results reveal that the maximal amounts of adsorbed oxygen species on the surface of the nanostructure Ce-R catalyst should be the crucial role to decide the catalytic soot performance. High BET surface area may also be a positive effect on soot oxidation activity under loose contact conditions. PMID:27353143

  12. Composite metal-hydrogen electrodes for metal-hydrogen batteries. Final report, October 1, 1993 - April 15, 1997

    International Nuclear Information System (INIS)

    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 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 modern electronic devices

  13. The potential and challenges of thin-film electrolyte and nanostructured electrode for yttria-stabilized zirconia-base anode-supported solid oxide fuel cells

    Science.gov (United States)

    Noh, Ho-Sung; Yoon, Kyung Joong; Kim, Byung-Kook; Je, Hae-June; Lee, Hae-Weon; Lee, Jong-Ho; Son, Ji-Won

    2014-02-01

    Thin-film electrolytes and nanostructured electrodes are essential components for lowering the operation temperature of solid oxide fuel cells (SOFCs); however, reliably implementing thin-film electrolytes and nano-structure electrodes over a realistic SOFC platform, such as a porous anode-support, has been extremely difficult. If these components can be created reliably and reproducibly on porous substrates as anode supports, a more precise assessment of their impact on realistic SOFCs would be possible. In this work, structurally sound thin-film and nano-structured SOFC components consisting of a nano-composite NiO-yttria-stabilized zirconia (YSZ) anode interlayer, a thin YSZ and gadolinia-doped ceria (GDC) bi-layer electrolyte, and a nano-structure lanthanum strontium cobaltite (LSC)-base cathode, are sequentially fabricated on a porous NiO-YSZ anode support using thin-film technology. Using an optimized cell testing setup makes possible a more exact investigation of the potential and challenges of thin-film electrolyte and nanostructured electrode-based anode-supported SOFCs. Peak power densities obtained at 500 °C surpass 500 mW cm-2, which is an unprecedented low-temperature performance for the YSZ-based anode-supported SOFC. It is found that this critical, low-temperature performance for the anode-supported SOFC depends more on the electrode performance than the resistance of the thin-film electrolyte during lower temperature operation.

  14. Hydrogen transfer reaction of cyclohexanone with 2-propanol catalysed by CeO2-ZnO materials: Promoting effect of ceria

    Indian Academy of Sciences (India)

    Braja Gopal Mishra; G Ranga Rao; B Poongodi

    2003-10-01

    Ce-Zn-O mixed oxides were prepared by amorphous citrate process and decomposition of the corresponding acetate precursors. The resulting materials were characterised by TGA, XRD, UV-Vis-DRS, EPR, SEM and surface area measurements. XRD and DRS results indicated fine dispersion of the ceria component in the ZnO matrix. EPR results clearly indicate the presence of oxygen vacancy and defect centres in the composite oxide. Addition of CeO2 to ZnO produced mixed oxides of high surface area compared to the pure ZnO. Hydrogen transfer reaction was carried out on these catalytic materials to investigate the effect of rare earth oxide on the activity of ZnO. Addition of ceria into zinc oxide was found to increase the catalytic activity for hydrogen transfer reaction. The catalytic activity also depended on the method of preparation. Citrate process results in uniformly dispersed mixed oxide with higher catalytic activity.

  15. Vanadium Pentoxide Nanobelt-Reduced Graphene Oxide Nanosheet Composites as High-Performance Pseudocapacitive Electrodes: ac Impedance Spectroscopy Data Modeling and Theoretical Calculations

    Directory of Open Access Journals (Sweden)

    Sanju Gupta

    2016-07-01

    Full Text Available Graphene nanosheets and graphene nanoribbons, G combined with vanadium pentoxide (VO nanobelts (VNBs and VNBs forming GVNB composites with varying compositions were synthesized via a one-step low temperature facile hydrothermal decomposition method as high-performance electrochemical pseudocapacitive electrodes. VNBs from vanadium pentoxides (VO are formed in the presence of graphene oxide (GO, a mild oxidant, which transforms into reduced GO (rGOHT, assisting in enhancing the electronic conductivity coupled with the mechanical robustness of VNBs. From electron microscopy, surface sensitive spectroscopy and other complementary structural characterization, hydrothermally-produced rGO nanosheets/nanoribbons are decorated with and inserted within the VNBs’ layered crystal structure, which further confirmed the enhanced electronic conductivity of VNBs. Following the electrochemical properties of GVNBs being investigated, the specific capacitance Csp is determined from cyclic voltammetry (CV with a varying scan rate and galvanostatic charging-discharging (V–t profiles with varying current density. The rGO-rich composite V1G3 (i.e., VO/GO = 1:3 showed superior specific capacitance followed by VO-rich composite V3G1 (VO/GO = 3:1, as compared to V1G1 (VO/GO = 1:1 composite, besides the constituents, i.e., rGO, rGOHT and VNBs. Composites V1G3 and V3G1 also showed excellent cyclic stability and a capacitance retention of >80% after 500 cycles at the highest specific current density. Furthermore, by performing extensive simulations and modeling of electrochemical impedance spectroscopy data, we determined various circuit parameters, including charge transfer and solution resistance, double layer and low frequency capacitance, Warburg impedance and the constant phase element. The detailed analyses provided greater insights into physical-chemical processes occurring at the electrode-electrolyte interface and highlighted the comparative performance of

  16. Li2Ni(0.5)Mn(0.5)SnO4/C: A Novel Hybrid Composite Electrode for High Rate Applications.

    Science.gov (United States)

    Vellaisamy, Mani; Nallathamby, Kalaiselvi

    2015-09-01

    A novel Li2Ni(0.5)Mn(0.5)SnO4/C composite electrode, existing as a hybrid consisting of monoclinic Li2SnO3 and layered LiNi(0.5)Mn(0.5)O2, has been identified and validated for high capacity and high rate lithium battery applications. Of the components, LiNi(0.5)Mn(0.5)O2 upon discharge forms the corresponding dilithium oxide, viz., Li2Ni(0.5)Mn(0.5)O2, and facilitates the progressive electrochemical performance of the composite electrode. Similarly, Li2SnO3 upon discharge forms Li2O and SnO2, wherein the unacceptable volume expansion related issues of SnO2 are addressed by the buffering activity of Li2O phase. A combination of alloying/dealloying, conversion, and redox mechanism is responsible for the excellent electrochemical behavior of Li2Ni(0.5)Mn(0.5)SnO4/C electrode. With this newer formulation of dilithium stannate composite, a superior capacity of >3000 mAh g(-1) at 100 mA g(-1) current density has been demonstrated. The study opens up a newer gateway for the entry of Li2SnO3·LiM1M2O2 hybrid formulations for exploitation up to 1 A g(-1) rate, thus ensuring the sustainable development of potential electrode materials for high rate applications. PMID:26252728

  17. Growth of Ceria Nano-Islands on a Stepped Au(788 Surface

    Directory of Open Access Journals (Sweden)

    Teng Ma

    2015-08-01

    Full Text Available The growth morphology and structure of ceria nano-islands on a stepped Au(788 surface has been investigated by scanning tunneling microscopy (STM and low-energy electron diffraction (LEED. Within the concept of physical vapor deposition, different kinetic routes have been employed to design ceria-Au inverse model catalysts with different ceria nanoparticle shapes and arrangements. A two-dimensional superlattice of ceria nano-islands with a relatively narrow size distribution (5 ± 2 nm2 has been generated on the Au(788 surface by the postoxidation method. This reflects the periodic anisotropy of the template surface and has been ascribed to the pinning of ceria clusters and thus nucleation on the fcc domains of the herringbone reconstruction on the Au terraces. In contrast, the reactive evaporation method yields ceria islands elongated in [01-1] direction, i.e., parallel to the step edges, with high aspect ratios (~6. Diffusion along the Au step edges of ceria clusters and their limited step crossing in conjunction with a growth front perpendicular to the step edges is tentatively proposed to control the ceria growth under reactive evaporation conditions. Both deposition recipes generate two-dimensional islands of CeO2(111-type O–Ce–O single and double trilayer structures for submonolayer coverages.

  18. Understanding the Formation and Evolution of Ceria Nanoparticles Under Hydrothermal Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Tyrsted, Christoffer; Ørnsbjerg; #8197; Jensen, Kirsten Marie; Bøjesen, Espen Drath; Lock, Nina; Christensen, Mogens; Billinge, Simon J.L.; Brummerstedt; #8197; Iversen, Bo (Aarhus); (Columbia)

    2012-10-23

    The formation and evolution of ceria nanoparticles during hydrothermal synthesis was investigated by in-situ total scattering and powder diffraction. The nucleation of pristine crystalline ceria nanoparticles originated from previously unknown cerium dimer complexes. The nanoparticle growth was highly accelerated under supercritical conditions.

  19. Reversibility of hydrogen chemisorption on a ceria-supported rhodium catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, S.; Calvino, J.J.; Cifredo, G.A.; Izquierdo, J.M. Rodriguez (Univ. de Cadiz, Perto Real (Spain)); Perrichon, V.; Laachir, A. (Inst. de Recherches sur la Catalyse (France))

    1992-09-01

    Cerium dioxide is an important component of the so-called three-way catalysts. This work reports on some new aspects of the chemistry of hydrogen-ceria systems. It is shown that, at room temperature, in the presence of highly dispersed rhodium, ceria chemisorbs large amounts of hydrogen. As deduced from magnetic measurements carried out in situ, this spillover process leads to the reduction of ceria to an extent of 21% of the total amount of cerium ions present in the sample, which is roughly equivalent to the complete surface reduction of the oxide. It is found that over a highly hydroxylated sample the reduction of ceria induced by the spillover process is partly reversible even at 295 K. If the sample is pumped off at 773 K, the initial oxidation state of ceria is almost completely recovered. Both the rate and extent of hydrogen chemisorption on ceria were found to be sensitive to the specific pretreatment applied to the catalyst. Over bare ceria, hydrogen chemisorption at 298 K was negligible, temperatures as high as 473 K being necessary to activate the process. In contrast to the rhodium-containing catalyst, over pure ceria the desorption of hydrogen leads to a much larger extent to water formation, thus revealing a deeper irreversible reduction of the oxide.

  20. Eco-friendly Synthesis of Ceria Foam via Carboxymethylcellulose Gelation: Application for the Epoxidation of Chalcone

    Science.gov (United States)

    A simple and innovative process is described for the eco-friendly preparation of ceria foams via the carboxymethylcellulose gelation by Ce4+ cations; heat treatment of the ensuing xerogels produces ceria foams. The influence of the concentration of cerium and of the calcination t...

  1. Electrochemical quartz crystal microbalance measurement of a Li4Ti5O12 composite electrode in a carbonate electrolyte

    Science.gov (United States)

    Serizawa, Nobuyuki; Shono, Kumi; Kobayashi, Yo; Miyashiro, Hajime; Katayama, Yasushi; Miura, Takashi

    2015-11-01

    Electrochemical quartz crystal microbalance (EQCM) measurement is conducted with a Li4Ti5O12 (lithium titanium oxide, LTO)-coated quartz crystal electrode in a carbonate electrolyte (ethylene carbonate + dimethyl carbonate; 50: 50 vol%) containing 1 M LiPF6. In-situ monitoring of the mass change during the charge and discharge of the LTO electrode can be achieved quantitatively because of the "zero-strain" property of LTO with Li+ insertion and the probably low reactivity between LTO and the electrolyte. The local changes of viscosity and density of the electrolyte contacting the LTO electrode are detected via the resonance resistance of the quartz crystal electrode, suggesting the local concentrations of Li+ and counter anion changed significantly during insertion and extraction of Li+ in the organic electrolyte.

  2. Mesoporous composite nickel cobalt oxide/graphene oxide synthesized via a template-assistant co-precipitation route as electrode material for supercapacitors

    Science.gov (United States)

    Xu, Yanjie; Wang, Lincai; Cao, Peiqi; Cai, Chuanlin; Fu, Yanbao; Ma, Xiaohua

    2016-02-01

    A simple co-precipitation method utilizing SDS (sodium dodecyl sulfate) as template and ammonia as precipitant is successfully employed to synthesize nickel cobalt oxide/graphene oxide (NiCo2O4/GO) composite. The as-prepared composite (NCG-10) exhibits a high capacitance of 1211.25 F g-1, 687 F g-1 at the current density of 1 A g-1, 10 A g-1 and good cycling ability which renders NCG-10 as promising electrode material for supercapacitors. An asymmetric supercapacitor (ASC) (full button cell) has been constructed with NCG-10 as positive electrode and lab-made reduced graphene oxide (rGO) as negative electrode. The fabricated NCG-10//rGO with an extended stable operational voltage of 1.6 V can deliver a high specific capacitance of 144.45 F g-1 at a current density of 1 A g-1. The as-prepared NCG-10//rGO demonstrates remarkable energy density (51.36 W h kg-1 at 1 A g-1), high power density (50 kW kg-1 at 20 A g-1). The retention of capacitance is 88.6% at the current density of 8 A g-1 after 2000 cycles. The enhanced capacitive performance can be attributed to the improved specific surface area and 3D open area of NCG-10 generated by the pores and channels with the substantial function of SDS.

  3. Electrochemical behavior and voltammetric determination of acetaminophen based on glassy carbon electrodes modified with poly(4-aminobenzoic acid)/electrochemically reduced graphene oxide composite films

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wencai [Key Laboratory for Colloid and Interface Chemistry of State Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); School of Chemistry and Chemical Engineering, Qilu Normal University, Jinan 250013 (China); Huang, Hui; Gao, Xiaochun [Key Laboratory for Colloid and Interface Chemistry of State Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Ma, Houyi, E-mail: hyma@sdu.edu.cn [Key Laboratory for Colloid and Interface Chemistry of State Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2014-12-01

    Poly(4-aminobenzoic acid)/electrochemically reduced graphene oxide composite film modified glassy carbon electrodes (4-ABA/ERGO/GCEs) were fabricated by a two-step electrochemical method. The electrochemical behavior of acetaminophen at the modified electrode was investigated by means of cyclic voltammetry. The results indicated that 4-ABA/ERGO composite films possessed excellent electrocatalytic activity towards the oxidation of acetaminophen. The electrochemical reaction of acetaminophen at 4-ABA/ERGO/GCE is proved to be a surface-controlled process involving the same number of protons and electrons. The voltammetric determination of acetaminophen performed with the 4-ABA/ERGO modified electrode presents a good linearity in the range of 0.1–65 μM with a low detection limit of 0.01 μM (S/N = 3). In the case of using the 4-ABA/ERGO/GCE, acetaminophen and dopamine can be simultaneously determined without mutual interference. Furthermore, the 4-ABA/ERGO/GCE has good reproducibility and stability, and can be used to determine acetaminophen in tablets. - Highlights: • The 4-ABA/ERGO/GCE was fabricated by a two-step electrochemical method. • Electrochemical behavior of acetaminophen at the 4-ABA/ERGO/GCE was investigated. • The electrochemical sensor exhibited a low detection limit and good selectivity. • This sensor was applied to the detection of acetaminophen in commercial tablets.

  4. Electrochemical behavior and voltammetric determination of acetaminophen based on glassy carbon electrodes modified with poly(4-aminobenzoic acid)/electrochemically reduced graphene oxide composite films

    International Nuclear Information System (INIS)

    Poly(4-aminobenzoic acid)/electrochemically reduced graphene oxide composite film modified glassy carbon electrodes (4-ABA/ERGO/GCEs) were fabricated by a two-step electrochemical method. The electrochemical behavior of acetaminophen at the modified electrode was investigated by means of cyclic voltammetry. The results indicated that 4-ABA/ERGO composite films possessed excellent electrocatalytic activity towards the oxidation of acetaminophen. The electrochemical reaction of acetaminophen at 4-ABA/ERGO/GCE is proved to be a surface-controlled process involving the same number of protons and electrons. The voltammetric determination of acetaminophen performed with the 4-ABA/ERGO modified electrode presents a good linearity in the range of 0.1–65 μM with a low detection limit of 0.01 μM (S/N = 3). In the case of using the 4-ABA/ERGO/GCE, acetaminophen and dopamine can be simultaneously determined without mutual interference. Furthermore, the 4-ABA/ERGO/GCE has good reproducibility and stability, and can be used to determine acetaminophen in tablets. - Highlights: • The 4-ABA/ERGO/GCE was fabricated by a two-step electrochemical method. • Electrochemical behavior of acetaminophen at the 4-ABA/ERGO/GCE was investigated. • The electrochemical sensor exhibited a low detection limit and good selectivity. • This sensor was applied to the detection of acetaminophen in commercial tablets

  5. Electrochemical characterization of MnO2-based composite in the presence of salt-in-water and water-in-salt electrolytes as electrode for electrochemical capacitors

    Science.gov (United States)

    Gambou-Bosca, Axel; Bélanger, Daniel

    2016-09-01

    The effect of the electrolyte on the electrochemical utilization of manganese dioxide as active material for electrochemical capacitor was studied by cyclic voltammetry and electrochemical impedance spectroscopy. MnO2-based composite electrodes were characterized in salt-in-water (0.65 M K2SO4, 5 M LiNO3, 0.5 M LiNO3 and 0.5 M Ca(NO3)2) and water-in-salt (5 M LiTFSI (lithium bis-trifluoromethanesulfonimide)) electrolytes. Firstly, no effect of the cation valence on the specific capacitance was observed as similar values were measured in 0.5 M LiNO3 and 0.5 M Ca(NO3)2 aqueous solutions at both low and high scan rate, when a MnO2-based composite electrode was cycled in the pseudocapacitive potential region. Secondly, it was found that in 5 M LiTFSI, a MnO2 electrode is characterized by an extended potential stability window of about 1.4 V and exhibits a high specific capacitance of 239 F g-1 per active material mass at a scan rate of 2 mV s-1. However due to the low ionic conductivity of this solution, the rate capability is limited at high scan rate.

  6. Highly efficient dye-sensitized solar cells achieved through using Pt-free Nb2O5/C composite counter electrode and iodide-free redox couples

    Science.gov (United States)

    Li, Ling; Lu, Qi; Li, Wenyan; Li, Xiaowei; Hagfeldt, Anders; Zhang, Wenming; Wu, Mingxing

    2016-03-01

    To improve the catalytic activity of Nb2O5, a composite Nb2O5/C (Nb2O5 imbedded in carbon support) is synthesized with a simple in situ method and then introduced the composite into dye-sensitized solar cells (DSCs) as a counter electrode (CE) catalyst. Based on the analysis of the cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel-polarization curve measurements, the catalytic activity of the Nb2O5/C composite for the regeneration of iodide-free redox couples of polysulfide (T2/T-) and cobalt complex (Co3+/2+) is indeed enhanced significantly as compared with pure Nb2O5, because the composite electrode eliminates the particle aggregation and forms a mesoporous network structure with large pore size. The T2/T- electrolyte based DSCs with Nb2O5/C CE yields a high power conversion efficiency (PCE) of 6.11%, generating a great improvement of 63.8% as compared to the Pt CE based DSCs. In addition, the Nb2O5/C exhibits higher catalytic activity than Pt for regenerating the Co3+/2+ redox couple and the DSCs using Nb2O5/C CE shows a high PCE of 9.86%.

  7. Investigation of long term reactive stability of ceria for use in solar thermochemical cycles

    International Nuclear Information System (INIS)

    The use of an intermediate reactive material composed of cerium (IV) oxide (ceria) is explored for solar fuel production through a CO2-splitting thermochemical redox cycle. To this end, powder and porous ceria samples are tested with TGA (thermogravimetric analysis) to ascertain their maximum fuel production potential from the CeO2 → CeO2−δ cycle. A maximum value of the non-stoichiometric reduction factor δ of ceria powder was 0.0383 at 1450 °C. The reactive stability of a synthesized porous ceria sample is then observed with carbon dioxide splitting at 1100 °C and thermal reduction at 1450 °C. Approximately 86.4% of initial fuel production is retained after 2000 cycles, and the mean value of δ is found to be 0.0197. SEM (scanning electron microscopy) imaging suggests that the porous ceria structure is retained over 2000 cycles despite apparent loss of some surface area. EDS (energy dispersive x-ray spectroscopy) line scans show that oxidation of porous ceria becomes increasingly homogenous throughout the bulk material over an increasing number of cycles. Significant retention of reactivity and porous structure demonstrates the potential of porous ceria for use in a commercial thermochemical reactor. - Highlights: • Ceria is explored for solar fuel production through a CO2-splitting redox cycle. • Stability of porous ceria is observed with carbon dioxide splitting at 1100 °C. • Greater than 86% of initial fuel production is retained after 2000 cycles. • SEM imaging reveals that the porous structure is retained over 2000 cycles. • Findings reveal that ceria structures are compatible with actual implementation

  8. Disinfection effects of undoped and silver-doped ceria powders of nanometer crystallite size

    Directory of Open Access Journals (Sweden)

    Tsai DS

    2016-06-01

    Full Text Available Dah-Shyang Tsai,1 Tzu-Sen Yang,2,3 Yu-Sheng Huang,1 Pei-Wen Peng,2,4 Keng-Liang Ou3,4 1Department of Chemical Engineering, National Taiwan University of Science and Technology, 2School of Dental Technology, 3Graduate Institute of Biomedical Materials and Tissue Engineering, 4Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei, Taiwan Abstract: Being endowed with an ability of capturing and releasing oxygen, the ceria surface conventionally assumes the role of catalyzing redox reactions in chemistry. This catalytic effect also makes possible its cytotoxicity toward microorganisms at room temperature. To study this cytotoxicity, we synthesized the doped and undoped ceria particles of 8–9 nm in size using an inexpensive precipitation method and evaluated their disinfecting aptitudes with the turbidimetric and plate count methods. Among the samples being analyzed, the silver-doped ceria exhibits the highest sterilization ability, yet the undoped ceria is the most intriguing. The disinfection effect of undoped ceria is moderate in magnitude, demanding a physical contact between the ceria surface and bacteria cell wall, or the redox catalysis that can damage the cell wall and result in the cell killing. Evidently, this effect is short-range and depends strongly on dispersion of the nanoparticles. In contrast, the disinfection effects of silver-doped ceria reach out several millimeters since it releases silver ions to poison the surrounding microorganisms. Additionally, the aliovalent silver substitution creates more ceria defects. The synergetic combination, silver poisoning and heterogeneous redox catalysis, lifts and extends the disinfecting capability of silver-doped ceria to a superior level. Keywords: ceria nanoparticle, antibacterial activity, cytotoxicity, oxygen vacancy, reactive oxygen species

  9. Composition analysis of the passive film on the carbon electrode of a lithium-ion battery with an EC-based electrolyte

    Science.gov (United States)

    Yang, C. R.; Wang, Y. Y.; Wan, C. C.

    This work examines the formation of a passive film on the carbon electrode of lithium-ion batteries. With a single solvent of EC (ethylene carbonate), the structure of the passive film is found to be (CH 2OCOOLi) 2. In a DEC (diethyl carbonate) or DMC (dimethyl carbonate) system, C 2H 5OCOOLi and Li 2CO 3 are formed on the surface of the carbon electrode. According to results from mass spectra, CO 2 gas is the main product when EC is decomposed. By contrast, DEC is decomposed into CO and C 2H 6, and DMC into CO and CH 4. These findings suggest that the composition of the passive film depends on the chosen solvent. In a binary solvent system which contains EC, the passive film contains chiefly (CH 2OCOOLi) 2, which is identical to a single EC solvent system.

  10. Room-temperature solution-processed and metal oxide-free nano-composite for the flexible transparent bottom electrode of perovskite solar cells

    Science.gov (United States)

    Lu, Haifei; Sun, Jingsong; Zhang, Hong; Lu, Shunmian; Choy, Wallace C. H.

    2016-03-01

    The exploration of low-temperature and solution-processed charge transporting and collecting layers can promote the development of low-cost and large-scale perovskite solar cells (PVSCs) through an all solution process. Here, we propose a room-temperature solution-processed and metal oxide-free nano-composite composed of a silver nano-network and graphene oxide (GO) flawless film for the transparent bottom electrode of a PVSC. Our experimental results show that the amount of GO flakes play a critical role in forming the flawless anti-corrosive barrier in the silver nano-network through a self-assembly approach under ambient atmosphere, which can effectively prevent the penetration of liquid or gaseous halides and their corrosion against the silver nano-network underneath. Importantly, we simultaneously achieve good work function alignment and surface wetting properties for a practical bottom electrode by controlling the degree of reduction of GO flakes. Finally, flexible PVSC adopting the room-temperature and solution-processed nano-composite as the flexible transparent bottom electrode has been demonstrated on a polyethylene terephthalate (PET) substrate. As a consequence, the demonstration of our room-temperature solution-processed and metal oxide-free flexible transparent bottom electrode will contribute to the emerging large-area flexible PVSC technologies.The exploration of low-temperature and solution-processed charge transporting and collecting layers can promote the development of low-cost and large-scale perovskite solar cells (PVSCs) through an all solution process. Here, we propose a room-temperature solution-processed and metal oxide-free nano-composite composed of a silver nano-network and graphene oxide (GO) flawless film for the transparent bottom electrode of a PVSC. Our experimental results show that the amount of GO flakes play a critical role in forming the flawless anti-corrosive barrier in the silver nano-network through a self

  11. Microcavity-Free Broadband Light Outcoupling Enhancement in Flexible Organic Light-Emitting Diodes with Nanostructured Transparent Metal-Dielectric Composite Electrodes.

    Science.gov (United States)

    Xu, Lu-Hai; Ou, Qing-Dong; Li, Yan-Qing; Zhang, Yi-Bo; Zhao, Xin-Dong; Xiang, Heng-Yang; Chen, Jing-De; Zhou, Lei; Lee, Shuit-Tong; Tang, Jian-Xin

    2016-01-26

    Flexible organic light-emitting diodes (OLEDs) hold great promise for future bendable display and curved lighting applications. One key challenge of high-performance flexible OLEDs is to develop new flexible transparent conductive electrodes with superior mechanical, electrical, and optical properties. Herein, an effective nanostructured metal/dielectric composite electrode on a plastic substrate is reported by combining a quasi-random outcoupling structure for broadband and angle-independent light outcoupling of white emission with an ultrathin metal alloy film for optimum optical transparency, electrical conduction, and mechanical flexibility. The microcavity effect and surface plasmonic loss can be remarkably reduced in white flexible OLEDs, resulting in a substantial increase in the external quantum efficiency and power efficiency to 47.2% and 112.4 lm W(-1). PMID:26687488

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

    Science.gov (United States)

    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

  13. Highly sensitive detection of 2,4,6-trichlorophenol based on HS-β-cyclodextrin/gold nanoparticles composites modified indium tin oxide electrode

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted -- Highlights: •A novel electrochemical sensing platform by self-assembling of HS-β-cyclodextrin/gold nanoparticles onto indium tin oxide electrode (HS-β-CD/AuNPs/SAM/ITO electrode) surface was constructed. •The proposed electrochemical sensor exhibited high sensitivity for the determination 2,4,6-trichlorophenol which electrochemical activity is very weak. •The newly developed method was successfully applied to quantitatively determine 2,4,6-trichlorophenol in tap water samples. -- ABSTRACT: A new electrochemical sensor for determination of 2,4,6-trichlorophenol (2,4,6-TCP) was fabricated. The characterization of the sensor was studied by scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry techniques. The electrochemical behavior of 2,4,6-TCP was investigated using cyclic voltammetry and differential pulse voltammetry at the HS-β-cyclodextrin (HS-β-CD)/gold nanoparticles (AuNPs) composite modified indium tin oxide (ITO) electrode. The results showed that the current responses of 2,4,6-TCP greatly enhanced due to the high catalytic activity and enrichment capability of composites. The peak current of 2,4,6-TCP increases linearly with the increase of the 2,4,6-TCP concentration from 3.0 × 10−9 to 2.8 × 10−8 M, with the limit of detection of 1.0 × 10−9. Further more, the modified electrode was successfully applied to detect the level of 2,4,6-TCP in tap water samples with excellent sensitivity

  14. Enhanced direct electron transfer reactivity of hemoglobin in cationic gemini surfactant-room temperature ionic liquid composite film on glassy carbon electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Li Jiangwen; Liu Lihong; Yan Rui; Xiao Mengying; Liu Liqin [Department of Chemistry, Wuhan University, Wuhan 430072 (China); Zhao Faqiong [Department of Chemistry, Wuhan University, Wuhan 430072 (China)], E-mail: zhaofq@chem.edu.cn; Zeng Baizhao [Department of Chemistry, Wuhan University, Wuhan 430072 (China)

    2008-05-20

    A novel composite film comprising cationic gemini surfactant butyl-{alpha},{omega}-bis(dimethylcetylammonium bromide) (C{sub 16}H{sub 33}N(CH{sub 3}){sub 2}-C{sub 4}H{sub 8}-N(CH{sub 3}){sub 2}C{sub 16}H{sub 33}, C{sub 16}-C{sub 4}-C{sub 16}) and ionic liquid 1-octyl-3-methylimidazolium hexafluorophate (OMIMPF{sub 6}) has been prepared. The composite film shows good biocompatibility and it can promote the direct electron transfer between hemoglobin (Hb) and glassy carbon (GC) electrode. On the C{sub 16}-C{sub 4}-C{sub 16} (dissolved in ethanol)-OMIMPF{sub 6} film coated GC electrode, the immobilized Hb can exhibit a pair of well-defined, quasi-reversible and stable redox peaks with a formal potential of -0.317 V (vs SCE) in 0.10 M pH 7 phosphate buffer solutions. The electron transfer coefficient ({alpha}) of Hb is calculated to be 0.44 and the heterogeneous electron transfer rate constant is 6.08 s{sup -1}. With the length of alkyl chains of gemini surfactant increasing and the ethanol concentration rising, the redox peaks of the resulting electrode C{sub 16}-C{sub 4}-C{sub 16}-OMIMPF{sub 6}-Hb/GC become bigger. The electrode presents good electrocatalytic response to peroxide hydrogen. The kinetic parameters I{sub max} and k{sub m} for the catalytic reaction are estimated. In addition, UV-vis spectra and reflectance absorption infrared spectra demonstrate that the Hb immobilized in the C{sub 16}-C{sub 4}-C{sub 16}-OMIMPF{sub 6} film almost retains the structure of native Hb.

  15. Electrochemical oxidation of adenosine-5 Prime -triphosphate on a chitosan-graphene composite modified carbon ionic liquid electrode and its determination

    Energy Technology Data Exchange (ETDEWEB)

    Sun Wei, E-mail: swyy26@hotmail.com [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou, 571158 (China); College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Liu Jun; Wang Xiuzhen; Li Tongtong; Li Guangjiu; Wu Jie [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Zhang Liqi [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2012-10-01

    In this paper a new electrochemical method was proposed for the determination of adenosine-5 Prime -triphosphate (ATP) based on a chitosan (CTS) and graphene (GR) composite film modified carbon ionic liquid electrode (CTS-GR/CILE). CILE was fabricated by using ionic liquid 1-butyl-3-methylimidazolium dihydrogen phosphate ([BMIM]H{sub 2}PO{sub 4}) as the binder, which was further modified by GR and CTS composite. The modified electrode exhibited an excellent electrocatalytic activity toward the oxidation of ATP with the increase of the oxidation peak current and the decrease of the oxidation peak potential. The electrochemical parameters of ATP on CTS-GR/CILE were calculated with the electron transfer coefficient ({alpha}) as 0.329, the electron transfer number (n) as 2.15, the apparent heterogeneous electron transfer rate constant (ks) as 3.705 Multiplication-Sign 10{sup -5} s{sup -1} and the surface coverage ({Gamma}{sub T}) as 9.33 Multiplication-Sign 10{sup -10} mol cm{sup -2}. Under the optimal conditions the oxidation peak current was proportional to ATP concentration in the range from 1.0 Multiplication-Sign 10{sup -6} to 1.0 Multiplication-Sign 10{sup -3} M with the detection limit of 0.311 {mu}M (S/N = 3). The proposed electrode showed excellent reproducibility, stability, anti-interference ability and further successfully applied to the ATP injection sample detection. - Highlights: Black-Right-Pointing-Pointer Ionic liquid [BMIM]H{sub 2}PO{sub 4} based carbon ionic liquid electrode (CILE) was prepared. Black-Right-Pointing-Pointer Graphene modified CILE was fabricated for the sensitive electrochemical detection of ATP. Black-Right-Pointing-Pointer Good electrocatalytic ability to the ATP oxidation was achieved. Black-Right-Pointing-Pointer Detection of 5 Prime -ATP in commercial injection samples with satisfactory results.

  16. Indium-free Cu/fluorine doped ZnO composite transparent conductive electrodes with stretchable and flexible performance on poly(ethylene terephthalate) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jun; Gong, Haibo; Yang, Xiaopeng; Qiu, Zhiwen; Zi, Min; Qiu, Xiaofeng [Key Lab of Inorganic Functional Material in Universities of Shandong, School of Material Science and Engineering, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Wang, Hongqiang [Stephenson Institute for Renewable Energy, Department of Chemistry, University of Liverpool, Peach Street, Liverpool L69 7ZF (United Kingdom); Cao, Bingqiang, E-mail: mse_caobq@ujn.edu.cn [Key Lab of Inorganic Functional Material in Universities of Shandong, School of Material Science and Engineering, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China)

    2015-03-30

    Graphical abstract: - Highlights: • Cu/FZO bilayer films grow on PET substrates at room temperature. • The lowest resistivity of 6.6 × 10{sup −5} Ω cm is obtained. • The Cu/FZO film exhibits mechanical flexibility and stability. - Abstract: Material-abundant ZnO and metal thin film have been proposed as potential alternatives for the most widely commercial indium tin oxide (ITO) transparent and conductive electrode. Yet the deterioration of optical transparency and conductivity for these materials makes them difficult to compete with ITO. In this work, a double-layer structured film-composed of FZO and Cu film is presented at room temperature, which combines the high transparency of FZO and high conductivity of Cu film. We first studied the effect of oxygen pressure on the transparency and conductivity of free-standing FZO layer deposited on poly(ethylene terephthalate) (PET) by PLD method. Also the structural, electrical, and optical properties of bilayers electrode dependence on the Cu layer thickness were optimized in detail. As the Cu layer thickness increases, the resistivity decreases. The lowest resistivity of 6.6 × 10{sup −5} Ω cm with a carrier concentration of 1.11 × 10{sup 22} cm{sup −3} and mobility of 8.52 cm{sup 2} V{sup −1} s{sup −1} was obtained at the optimum Cu (12 nm) layer thickness. We find that FZO layer have anti-reflection effect for Cu/FZO (250 nm) bilayer in the wavelength range of 650–1000 nm compared with single Cu layer. And we firstly study the stretchable performance for Cu film-based composite electrodes with stretching ratio changing from 0 to 5%. Furthermore, we study excellent mechanical flexibility and stability of composite electrodes by bending test.

  17. Reduced graphene oxide and polypyrrole/reduced graphene oxide composite coated stretchable fabric electrodes for supercapacitor application

    International Nuclear Information System (INIS)

    Highlights: • Stretchable rGO coated fabric electrode was prepared by a dyeing approach. • This conductive fabric could sustain conductivity at 200% strain. • Its specific capacitance was improved after a polypyrrole coating. • These stretchable electrodes showed improved performance at 50% strain. -- Abstract: The advent of self-powered functional garments has given rise to a demand for stretchable energy storage devices that are amendable to integration into textile structures. The electromaterials (anode, cathode and separator) are expected to sustain a deformation of 3% to 55% associated with body movement. Here, we report a stretchable fabric supercapacitor electrode using commonly available nylon lycra fabric as the substrate and graphene oxide (GO) as a dyestuff. It was prepared via a facile dyeing approach followed by a mild chemical reduction. This reduced graphene oxide (rGO) coated fabric electrode retains conductivity at an applied strain of up to 200%. It delivers a specific capacitance of 12.3 F g−1 at a scan rate of 5 mV s−1 in 1.0 M lithium sulfate aqueous solution. The capacitance is significantly increased to 114 F g−1 with the addition of a chemically synthesized polypyrrole (PPy) coating. This PPy-rGO-fabric electrode demonstrates an improved cycling stability and a higher capacitance at 50% strain when compared to the performance observed with no strain

  18. Catalytic Activity of Ceria-Zirconia Nanostructured Materials Prepared via Reversed Microemulsion Method

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Single-phase homogeneous Ce1- xZrxO2 solid solutions with various compositions were synthesized using the reversed microemulsion method. The structural properties and performance of Ce1- x ZrxO2 were studied using XRD, BET,SEM, HRTEM, TPR and CO oxidation measurements. The results show that in the range of x = 0.4 ~ 0.5 and x = 0.6 ~1.0, the solid solutions posses the cubic and the tetragonal phase structure, respectively. Solids obtained by the reversed microemulsion method were more homogeneous on the whole range of composition. XRD investigations of the prepared materials did not show segregation of cerium or zirconium oxides. Highly uniform nanosize solid solution particles of ceria-ziroxidation measurements indicate that the performance of the CeO2-ZrO2 mixed oxides is strongly related to the composition and structure of the oxides. Enhancement of the activity was found for the catalyst prepared by reversed microemulsion method as compared to the sample prepared by sol-gel method.

  19. Electro-oxidation of chlorophenols on poly(3,4-ethylenedioxythiophene)-poly(styrene sulphonate) composite electrode

    Energy Technology Data Exchange (ETDEWEB)

    Pigani, L. [Dipartimento di Chimica, Universita di Modena e Reggio Emilia, via G. Campi, 18, 41100 Modena (Italy); Musiani, M. [Istituto per l' Energetica e le Interfasi, IENI-CNR, Corso Stati Uniti 4, 35127 Padova (Italy); Pirvu, C. [Department of General Chemistry, University Politehnica of Bucharest, Calea Grivitei 132, 78126 Bucharest (Romania); Terzi, F. [Dipartimento di Chimica, Universita di Modena e Reggio Emilia, via G. Campi, 18, 41100 Modena (Italy); Zanardi, C. [Dipartimento di Chimica, Universita di Modena e Reggio Emilia, via G. Campi, 18, 41100 Modena (Italy); Seeber, R. [Dipartimento di Chimica, Universita di Modena e Reggio Emilia, via G. Campi, 18, 41100 Modena (Italy)]. E-mail: reseeber@unimore.it

    2007-01-01

    The electrochemical behaviour of chlorinated phenols on Pt/poly(3,4-ethylenedioxy)thiophene,LiClO{sub 4} and on Pt/poly(3,4-ethylenedioxy)thiophene,poly(sodium-4-styrenesulphonate) electrodes has been investigated in phosphate buffer solution. Poly(sodium-4-styrenesulphonate) exerts remarkable effect against the electrode fouling induced by oxidation of chlorophenols, allowing us to record the relevant anodic response even after repeated potential cycles. Hypotheses about the role exerted by poly(sodium 4-styrenesulphonate) are made, on the basis of evidences provided by several techniques, such as cyclic voltammetry, electrochemical impedance spectroscopy, electrochemical microgravimetry and atomic force microscopy. Thanks to the fact that different chlorophenols show differences in the voltammetric responses, depending on number and position of the chloro substituents on the aromatic ring, applications of the modified electrode in the analysis of mixtures of chlorinated phenols are possible.

  20. Physical and electrochemical properties of supercapacitor composite electrodes prepared from biomass carbon and carbon from green petroleum coke

    Science.gov (United States)

    Awitdrus, Deraman, M.; Talib, I. A.; Farma, R.; Omar, R.; Ishak, M. M.; Taer, E.; Dolah, B. N. M.; Basri, N. H.; Nor, N. S. M.

    2015-04-01

    The green monoliths (GMs) were prepared from the mixtures of pre-carbonized fibers of oil palm empty fruit bunches (or self-adhesive carbon grains (SACG)) and green petroleum coke (GPC) with the mixing ratio of 0, 10, 30, 50 and 70 % GPC, respectively. The GMs were carbonized in N2 environment at 800°C to produce carbon monoliths (CM00, CM10, CM30, CM50 and CM70). The CMs were CO2 activated at 800°C for 1 hour to produced activated carbon monolith electrodes (ACM00, ACM10, ACM30, ACM50 and ACM70). For each percentage of GPC, three duplicate symmetrical supercapacitor cells were fabricated using these activated carbon monolith electrodes respectively, and the capacitive performance amongst the cells was compared and analyzed in order to observe the relationship between the capacitive performance and the physical properties (microstructure and porosity) of the ACMs electrodes containing varying percentage of GPC.

  1. γ-Mo2N/Co3Mo3N composite material for electrochemical supercapacitor electrode

    International Nuclear Information System (INIS)

    A novel class of electrochemical supercapacitors electrode material has been synthesized using temperature-programmed reaction (TPR) CoMoO4 precursors prepared using a mixture of an aqueous solution of Co(NO3).6H2O and (NH4)6Mo7O24.4H2O with ammonia. This material was physically and chemically characterized by X-ray diffraction microscopy (XRD), scanning electron microcopy (SEM), and cyclic voltammetry (CV). CV characterization indicated fast kinetics for charge-discharge process as well as good kinetic reversibility. The material provided 109.9 F g-1 specific capacitance over a potential window of about -0.25 ± 0.55 V versus saturation calomel reference electrode (versus SCE) in aqueous electrolyte. It is, therefore, a possible candidate as material applicable for electrochemical supercapacitors electrode

  2. Glucose aided synthesis of molybdenum sulfide/carbon nanotubes composites as counter electrode for high performance dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • The glucose aided (G-A) preparation of MoS2/CNTs composites were employed as CE in Pt-free DSSC. • The (G-A) MoS2/CNTs* CE showed the low Rct of 1.77 Ω cm2. • The efficiency of the DSSC reached 7.92% based on the (G-A) MoS2/CNTs* CE. - Abstract: In our present study, the composites of molybdenum disulfide/carbon nanotubes (MoS2/CNTs) were synthesized with glucose aided (G-A) by using an in situ hydrothermal route, and proposed as counter electrode (CE) catalyst in the dye-sensitized solar cells (DSSCs) for enhancing electrocatalytic activity toward the reduction of triiodide. The MoS2/CNTs composites with tentacle-like structure were confirmed by using the scanning and transmission electron microscopy. The superior structural characteristics including large active surface area and particularly the unique tentacle-like nanostructure along with 3D large interconnected interstitial volume guaranteed fast mass transport for the electrolyte, and enabled the (G-A) MoS2/CNTs CE to speed up the reduction of triiodide to iodide. The extensive electrochemical studies by the cyclic voltammetry, electrochemical impedence spectroscopy and Tafel measurements indicated that the (G-A) MoS2/CNTs CE possessed superior electrocatalytic activity, great electrochemical stability and impressive low charge transfer resistance on the electrolyte|electrode interface (1.77 Ω cm2) in the triiodide/iodide system compared to the pristine MoS2, MoS2/C and sputtered Pt CEs. The DSSC assembled with the novel (G-A) MoS2/CNTs CE exhibited high power conversion efficiency of 7.92% under the illumination of 100 mW cm−2, comparable to that of the DSSC with the Pt electrode (7.11%)

  3. Synthesis and silica coating of calcia-doped ceria/mica nanocomposite by seeded polymerization technique

    Energy Technology Data Exchange (ETDEWEB)

    El-Toni, Ahmed Mohamed [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)]. E-mail: el-toni@mail.tagen.tohoku.ac.jp; Yin, Shu [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Sato, Tsugio [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

    2006-05-15

    Calcia-doped ceria is of potential interest as an ultraviolet (UV) radiation blocking material in personal care products because of the excellent UV light absorption property and low catalytic ability for the oxidation of organic materials superior to undoped ceria. In order to reduce the oxidation catalytic activity further, calcia-doped ceria was coated with amorphous silica by means of seeded polymerization technique. Generally, nanoparticles of inorganic materials do not provide a good coverage for human skin because of the agglomeration of the particles. The platy particles are required to enhance the covering ability of inorganic materials. This can be accomplished by synthesis of calcia-doped ceria/mica nanocomposite with subsequent silica coating to control catalytic activity of calcia-doped ceria. Calcia-doped ceria/mica nanocomposite was prepared by soft solution chemical method followed by silica coating via seeded polymerization technique. Silica coated calcia-doped ceria/mica nanocomposite was characterized by X-ray diffraction, SEM, TEM, XPS and FT-IR.

  4. Trace analysis of Ponceau 4R in soft drinks using differential pulse stripping voltammetry at SWCNTs composite electrodes based on PEDOT:PSS derivatives.

    Science.gov (United States)

    Wang, Zifei; Zhang, Hui; Wang, Zhipeng; Zhang, Jie; Duan, Xuemin; Xu, Jingkun; Wen, Yangping

    2015-08-01

    Ponceau 4R, an edible synthetic colorant used in drinks, syrups, and sweets, has been successfully detected using differential pulse voltammetry at a single-walled carbon nanotubes-modified composite electrode based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) and two derivatives thereof. The electrochemical parameters of three Ponceau 4R sensors, such as pH value, pre-concentration time, and scan rate, have been optimized, and their electrochemical performances have been compared. A poly(acrylate-modified 3,4-ethylenedioxythiophene-co-3,4-ethylenedioxythiophene):poly(styrene sulfonate)-single-walled carbon nanotubes-poly(vinyl alcohol)-modified electrode showed the best electrocatalytic activity, with the highest response current, lowest detection limit (1.8 nm), widest linear range (0.0055-110.6 μm), and best sensing stability. Additionally, the modified electrode has also been successfully employed for real sample analysis with soft drinks. Satisfactory results were obtained, demonstrating this to be an easy and effective approach for trace analysis of Ponceau 4R in food samples. PMID:25766817

  5. Binderless Composite Electrode Monolith from Carbon Nanotube and Biomass Carbon Activated by H2 SO4 and CO2 Gas for Supercapacitor

    Science.gov (United States)

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

    2011-12-01

    Binderless composite electrodes in the monolithic form prepared from carbon nanotubes (CNTs) and self-adhesive carbon grains (SACG) from fibers of oil palm empty fruit bunch were studied as an electrode in a supercapacitor. The green monoliths (GMs) were prepared from three different types of precursors, SACG, SACG treated with 0.4 Molar H2 SO4 and mixture of SACG and 5% CNTs (by weight) treated with 0.4 Molar H2 SO4 , respectively. These GMs were carbonized at 600 ° C in N2 gas environment and activated by CO2 gas at 800 ° C for 1 hour to produce activated carbon monoliths (ACMs). The properties of the ACMs (density, porosity, microstructure, structure and electrical conductivity) were found affected by CNTs addition and acid treatment. The acid treatment did not improve the electrochemical behavior of the ACMs used as electrodes (specific capacitance, specific energy and specific power of the supercapacitor) in the supercapacitor cells but CNTs addition improves the equivalent series resistance of the cell.

  6. Highly sensitive response to dopamine at a modified electrode involving a composite film with Au nanoparticles dispersed in a fluorocarbon polymer

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A new approach for the highly sensitive detection of dopamine by a novel composite film involving gold nanoparticles trapped in a negatively-charged fluorocarbon polymer (Nafion) on a glassy carbon (GC) electrode fabricated by a simple method is described. Gold nanoparticles with an average diameter of 2.3 nm ± 0.2 nm are dispersed throughout the whole Nafion film. The introduction of gold nanoparticles into the Nafion film not only gives a highly active electrode surface area but also increases the conductivity of the Nafion film and the resulting Au/Nafion/GC electrode combines the advantages of the properties of gold nanoparticles and the selective pre-concentration ability of Nafion. For positively charged dopamine, the results show a decrease in the redox peak separation and a high sensitivity. The oxidation peak current of dopamine was shown to vary linearly with dopamine concentration over a wide range from 0.4 to 50.0 μmol/L with a detection limit of 0.3 μmol/L. Negatively charged ascorbic acid shows no redox waves at concentrations up to 1.0 ×10-4 mol/L.

  7. Enhancing electrocatalytic performance of Sb-doped SnO{sub 2} electrode by compositing nitrogen-doped graphene nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Tigang; Wen, Qing, E-mail: wenqing@hrbeu.edu.cn; Chen, Ye, E-mail: chenye@hrbeu.edu.cn; Zhou, Yiding; Duan, Ying

    2014-09-15

    Highlights: • Sb-doped SnO{sub 2} electrode is modified with nitrogen-doped graphene nanosheets. • Accelerated life of Ti/Sb-SnO{sub 2}-NGNS is 4.45 times as long as that of Ti/Sb-SnO{sub 2}. • Electroactive sites of Ti/Sb-SnO{sub 2}-NGNS are 1.43 times more than that of Ti/Sb-SnO{sub 2}. • The decolorization rate constant of MB on Ti/Sb-SnO{sub 2}-NGNS is 36.6 min{sup −1}. • The decolorization rate constant of OII on Ti/Sb-SnO{sub 2}-NGNS is 44.0 min{sup −1}. - Abstract: An efficient Ti/Sb-SnO{sub 2} electrode modified with nitrogen-doped graphene nanosheets (NGNS) was successfully fabricated by the sol–gel and dip coating method. Compared with Ti/Sb-SnO{sub 2} electrode, the NGNS-modified electrode possesses smaller unite crystalline volume (71.11 Å{sup 3} vs. 71.32 Å{sup 3}), smaller electrical resistivity (13 Ω m vs. 34 Ω m), and lower charge transfer resistance (10.91 Ω vs. 21.01 Ω). The accelerated lifetime of Ti/Sb-SnO{sub 2}-NGNS electrode is prolonged significantly, which is 4.45 times as long as that of Ti/Sb-SnO{sub 2} electrode. The results of X-ray photoelectron spectroscopy measurement and voltammetric charge analysis indicate that introducing NGNS into the active coating can increase more reaction active sites to enhance the electrocatalytic efficiency. The electrochemical dye decolorization analysis demonstrates that Ti/Sb-SnO{sub 2}-NGNS presents efficient electrocatalytic performance for methylene blue and orange II decolorization. And its pseudo-first order kinetic rate constants for methylene blue and orange II decolorization are 36.6 and 44.0 min{sup −1}, respectively, which are 6.0 and 7.1 times as efficient as those of Ti/Sb-SnO{sub 2}, respectively. Considering the significant electrocatalytic activity and low resistivity of Ti/Sb-SnO{sub 2}-NGNS electrode, the cost of wastewater treatment can be expected to be reduced obviously and the application prospect is broad.

  8. Electrocatalytical oxidation and sensitive determination of acetaminophen on glassy carbon electrode modified with graphene–chitosan composite

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Meixia; Gao, Feng [Department of Chemistry and Environmental Science, Zhangzhou Normal University, Zhangzhou 363000 (China); Wang, Qingxiang, E-mail: axiang236@126.com [Department of Chemistry and Environmental Science, Zhangzhou Normal University, Zhangzhou 363000 (China); Cai, Xili [Department of Chemistry and Environmental Science, Zhangzhou Normal University, Zhangzhou 363000 (China); Jiang, Shulian; Huang, Lizhang [Zhangzhou Product Quality Supervision and Inspection Institute, Zhangzhou 363000 (China); Gao, Fei [Department of Chemistry and Environmental Science, Zhangzhou Normal University, Zhangzhou 363000 (China)

    2013-04-01

    The electrochemical behaviors of acetaminophen (ACOP) on a graphene–chitosan (GR–CS) nanocomposite modified glassy carbon electrode (GCE) were investigated by cyclic voltammetry (CV), chronocoulometry (CC) and differential pulse voltammetry (DPV). Electrochemical characterization showed that the GR–CS nanocomposite had excellent electrocatalytic activity and surface area effect. As compared with bare GCE, the redox signal of ACOP on GR–CS/GCE was greatly enhanced. The values of electron transfer rate constant (k{sub s}), diffusion coefficient (D) and the surface adsorption amount (Γ{sup ⁎}) of ACOP on GR–CS/GCE were determined to be 0.25 s{sup −1}, 3.61 × 10{sup −5} cm{sup 2} s{sup −1} and 1.09 × 10{sup −9} mol cm{sup −2}, respectively. Additionally, a 2e{sup −}/2H{sup +} electrochemical reaction mechanism of ACOP was deduced based on the acidity experiment. Under the optimized conditions, the ACOP could be quantified in the range from 1.0 × 10{sup −6} to 1.0 × 10{sup −4} M with a low detection limit of 3.0 × 10{sup −7} M based on 3S/N. The interference and recovery experiments further showed that the proposed method is acceptable for the determination of ACOP in real pharmaceutical preparations. Highlights: ► A chitosan–graphene nanocomposite modified glassy carbon electrode was prepared. ► The modified electrode was electrochemically characterized by CV and EIS. ► Electro-oxidation of acetaminophen was examined on the modified electrode. ► Sensing analysis of the modified electrode toward acetaminophen was studied.

  9. Electrocatalytical oxidation and sensitive determination of acetaminophen on glassy carbon electrode modified with graphene–chitosan composite

    International Nuclear Information System (INIS)

    The electrochemical behaviors of acetaminophen (ACOP) on a graphene–chitosan (GR–CS) nanocomposite modified glassy carbon electrode (GCE) were investigated by cyclic voltammetry (CV), chronocoulometry (CC) and differential pulse voltammetry (DPV). Electrochemical characterization showed that the GR–CS nanocomposite had excellent electrocatalytic activity and surface area effect. As compared with bare GCE, the redox signal of ACOP on GR–CS/GCE was greatly enhanced. The values of electron transfer rate constant (ks), diffusion coefficient (D) and the surface adsorption amount (Γ⁎) of ACOP on GR–CS/GCE were determined to be 0.25 s−1, 3.61 × 10−5 cm2 s−1 and 1.09 × 10−9 mol cm−2, respectively. Additionally, a 2e−/2H+ electrochemical reaction mechanism of ACOP was deduced based on the acidity experiment. Under the optimized conditions, the ACOP could be quantified in the range from 1.0 × 10−6 to 1.0 × 10−4 M with a low detection limit of 3.0 × 10−7 M based on 3S/N. The interference and recovery experiments further showed that the proposed method is acceptable for the determination of ACOP in real pharmaceutical preparations. Highlights: ► A chitosan–graphene nanocomposite modified glassy carbon electrode was prepared. ► The modified electrode was electrochemically characterized by CV and EIS. ► Electro-oxidation of acetaminophen was examined on the modified electrode. ► Sensing analysis of the modified electrode toward acetaminophen was studied

  10. Preparation and electrocatalytic oxidation properties of a nickel pentacyanonitrosylferrate modified carbon composite electrode by two-step sol-gel technique: improvement of the catalytic activity

    International Nuclear Information System (INIS)

    The sol-gel technique was used to construct nickel pentacyanonitrosylferrate (NiPCNF) modified composite ceramic carbon electrodes (CCEs). This involves two steps: forming a CCE containing Ni powder and then immersing the electrode into a sodium pentacyanonitrosyl-ferrate solution (electroless deposition). The cyclic voltammograms of the resulting surface modified CCE under optimum conditions show a well-defined redox couple due to the [NiIIFeIII/II(CN)5NO]0/-1 system. The electrochemical properties and stability of the modified electrode were investigated by cyclic voltammetry. The apparent electron transfer rate constant (ks) and transfer coefficient (α) were determined by cyclic voltammetry being about 1.1 s-1 and 0.55, respectively. Sulfite has been chosen as a model to elucidate the electrocatalytic ability of NiPCNF-modified CCE prepared by one- or two-step sol-gel technique. The modified electrode showed excellent electrocatalytic activity toward the SO32- electro oxidation in pH range 3-9 in comparison with CCE modified by homogeneous mixture of graphite powder, Ni(NO3)2 and Na2[Fe(CN)5NO] (one-step sol-gel technique). Sulfite was determined amperometrically at the surface of this modified electrode in pH 7. Under the optimized conditions the calibration curve is linear in the concentration range 2 μM to 2.0 mM. The detection limit (signal-to-noise is 3) and sensitivity are 0.5 μM and 13.5 nA/μM. The modified carbon ceramic electrode containing nickel pentacyanonitrosylferrate shows good repeatability, short response time, t (90%) 2[Fe(CN)5NO] solution. The advantages of the SO32- amperometrically detector based on the nickel pentacyanonitrosylferrate-doped CCE is high sensitivity, inherent stability at wide pH range, excellent catalytic activity and less expense and simplicity of preparation. This sensor can be used as amperometric detector in chromatographic instruments

  11. Synthesis and characterization of plate-like ceria particles for cosmetic application

    International Nuclear Information System (INIS)

    Plate-like cerium oxide particles were successfully prepared by a facile precipitation process of cerium carbonate precursor followed by calcination in air at 400 deg. C. Ceria particles with the same morphology and slightly decreased particle size compare with those of plate-like cerium carbonate precursor were obtained. The particle size could be controlled by precisely adjusting pH value of the solution. In comparison with commercial ceria nanoparticles, the synthesized plate-like ceria particles showed lower oxidation catalytic activity, higher comfort of use and higher gloss value as well as excellent UV-shielding ability, indicating the potential application as a new cosmetic agent.

  12. Impact of doping on the ionic conductivity of ceria: A comprehensive model

    KAUST Repository

    Wang, Hao

    2013-06-13

    Doped ceria is considered as an electrolyte for solid oxide fuel cell applications. The introduction of dopants in the ceria lattice will affect its electronic structure and, in turn, its ionic conductivity. Simulation of these issues using density functional theory becomes complicated by the random distribution of the constituent atoms. Here we use the generalized gradient approximation with on-site Coulomb interaction in conjunction with the special quasirandom structures method to investigate 18.75% and 25% Y, Gd, Sm, Pr, and La doped ceria. The calculated lattice constants and O migration energies allow us to explain the behavior of the conductivity as obtained in experiments.

  13. Electrochemical sensors for the simultaneous determination of zinc, cadmium and lead using a Nafion/ionic liquid/graphene composite modified screen-printed carbon electrode.

    Science.gov (United States)

    Chaiyo, Sudkate; Mehmeti, Eda; Žagar, Kristina; Siangproh, Weena; Chailapakul, Orawon; Kalcher, Kurt

    2016-04-28

    A simple, low cost, and highly sensitive electrochemical sensor, based on a Nafion/ionic liquid/graphene composite modified screen-printed carbon electrode (N/IL/G/SPCE) was developed to determine zinc (Zn(II)), cadmium (Cd(II)), and lead (Pb(II)) simultaneously. This disposable electrode shows excellent conductivity and fast electron transfer kinetics. By in situ plating with a bismuth film (BiF), the developed electrode exhibited well-defined and separate peaks for Zn(II), Cd(II), and Pb(II) by square wave anodic stripping voltammetry (SWASV). Analytical characteristics of the BiF/N/IL/G/SPCE were explored with calibration curves which were found to be linear for Zn(II), Cd(II), and Pb(II) concentrations over the range from 0.1 to 100.0 ng L(-1). With an accumulation period of 120 s detection limits of 0.09 ng mL(-1), 0.06 ng L(-1) and 0.08 ng L(-1) were obtained for Zn(II), Cd(II) and Pb(II), respectively using the BiF/N/IL/G/SPCE sensor, calculated as 3σ value of the blank. In addition, the developed electrode displayed a good repeatability and reproducibility. The interference from other common ions associated with Zn(II), Cd(II) and Pb(II) detection could be effectively avoided. Finally, the proposed analytical procedure was applied to detect the trace metal ions in drinking water samples with satisfactory results which demonstrates the suitability of the BiF/N/IL/G/SPCE to detect heavy metals in water samples and the results agreed well with those obtained by inductively coupled plasma mass spectrometry. PMID:27046207

  14. Crystal Structure-Ionic Conductivity Relationships in Doped Ceria Systems

    DEFF Research Database (Denmark)

    Omar, Shobit; Wachsman, Eric D.; Jones, Jacob L.;

    2009-01-01

    high temperatures, the minimal elastic strain due to the presence of dopant is observed in Dy0.10Ce0.90O2−δ. Nd0.10Ce0.90O2−δ exhibits larger elastic lattice strain than Dy0.10Ce0.90O2−δ with better ionic conductivity at intermediate temperatures. Therefore, it is shown that the previously proposed......In the past, it has been suggested that the maximum ionic conductivity is achieved in ceria, when doped with an acceptor cation that causes minimum distortion in the cubic fluorite crystal lattice. In the present work, this hypothesis is tested by measuring both the ionic conductivity and elastic...... lattice strain of 10 mol% trivalent cation-doped ceria systems at the same temperatures. A consistent set of ionic conductivity data is developed, where the samples are synthesized under similar experimental conditions. On comparing the grain ionic conductivity, Nd0.10Ce0.90O2−δ exhibits the highest ionic...

  15. Characterization of swift heavy ion irradiation damage in ceria

    Energy Technology Data Exchange (ETDEWEB)

    Yablinsky, Clarissa A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Devanathan, Ram [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Pakarinen, Janne [Inst. for Nuclear Research Center (SCK-CEN), Mol, (Belgium); Gan, Jian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Severin, Daniel [GSI-Darmstadt (Germany); Trautmann, Christina [GSI-Darmstadt (Germany); Allen, Todd R. [Univ. of Wisconsin, Madison, WI (United States). Energy Physics Dept.

    2015-03-04

    Swift heavy ion induced radiation damage is investigated for ceria (CeO2), which serves as a UO2 fuel surrogate. Microstructural changes resulting from an irradiation with 940 MeV gold ions of 42 keV/nm electronic energy loss are investigated by means of electron microscopy accompanied by electron energy loss spectroscopy showing that there exists a small density reduction in the ion track core. While chemical changes in the ion track are not precluded, evidence of them was not observed. Classical molecular dynamics simulations of thermal spikes in CeO2 with an energy deposition of 12 and 36 keV/nm show damage consisting of isolated point defects at 12 keV/nm, and defect clusters at 36 keV/nm, with no amorphization at either energy. Inferences are drawn from modeling about density changes in the ion track and the formation of interstitial loops that shed light on features observed by electron microscopy of swift heavy ion irradiated ceria.

  16. Converse magnetoelectric effect in laminated composite of Metglas and Pb(Zr,TiO3 with screen-printed interdigitated electrodes

    Directory of Open Access Journals (Sweden)

    Yuan Zhang

    2014-06-01

    Full Text Available In this study, we investigate the converse magnetoelectric (CME effect in a laminated composite consisting of Metglas ribbons and Pb(Zr,TiO3 (PZT plate with screen-printed interdigitated electrodes and operating in longitudinal magnetization and longitudinal polarization (L-L mode. Large CME coefficients of 0.134 G·cm/V at frequency of 1 kHz and 2.75 G·cm/V at resonance frequency of 43.5 kHz under a small bias magnetic field of 7 Oe are achieved. The large CME effect can be attributed to the L-L mode and low mechanical loss of the Metglas/PZT laminated composite.

  17. Simultaneous removal of methylene blue and copper(II) ions by photoelectron catalytic oxidation using stannic oxide modified iron(III) oxide composite electrodes

    International Nuclear Information System (INIS)

    Highlights: • Photoelectron catalytic oxidation was used for methylene blue and Cu2+ removal. • SnO2/Fe2O3 was prepared and characterized for use as photoanodes and photocathodes. • Optimal reaction conditions were determined for methylene blue and Cu2+ removal. • Methylene blue removal followed the Langmuir–Freundlich–Hinshelwood kinetic model. • Cu2+ removal followed the first-order rate model. - Abstract: Stannic oxide modified Fe(III) oxide composite electrodes (SnO2/Fe2O3) were synthesized for simultaneously removing methylene blue (MB) and Cu(II) from wastewater using photoelectron catalytic oxidation (PEO). The SnO2/Fe2O3 electrodes were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoelectrochemical techniques. The removal of MB and Cu(II) by PEO using the SnO2/Fe2O3 composite electrodes was studied in terms of reaction time, electric current density, and pH of the electrolyte. The kinetics of the reactions were investigated using batch assays. The optimal reaction time, pH, and electric current density of the PEO process were determined to be 30 min, 6.0, and 10 mA/cm2, respectively. The removal rates of MB from wastewater treated by PEO and electron catalytic oxidation process were 84.87% and 70.64%, respectively, while the recovery rates of Cu(II) were 91.75% and 96.78%, respectively. The results suggest that PEO is an effective method for the simultaneous removal of MB and Cu(II) from wastewater, and the PEO process exhibits a much higher removal rate for MB and Cu(II) compared to the electron catalytic oxidation process. Furthermore, the removal of MB was found to follow the Langmuir–Freundlich–Hinshelwood kinetic model, whereas the removal of Cu(II) fitted well to the first-order reaction model

  18. Li EXCESS Li4+xTi5-xO12-δ/C COMPOSITE USING SPRAY-DRYING METHOD AND ITS ELECTRODE PROPERTIES

    Science.gov (United States)

    Yoshikawa, Daisuke; Suzuki, Norio; Kadoma, Yoshihiro; Ui, Koichi; Kumagai, Naoaki

    2012-03-01

    We have prepared a lithium excess carbon composite material, Li4+xTi5-xO12-δ/C (LTO/C), using various amounts of sucrose as a carbon source by the spray-drying method. The prepared materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and elemental analysis. The prepared material had the Li4Ti5O12 phase including 3.9-18.4 wt.% carbon. Transmission electron microscopy images and the selected area diffraction (SAD) pattern showed that the prepared materials consisted of a carbon nanonetwork in the LTO/C composite. The charge-discharge cycling tests were carried out using the R2032 coin-type cell under the following conditions; 1.2-3.0 V, 0.1 C-10 C (1 C = 175 mA g-1), 25°C. Based on the electrochemical results, the electrode performance of the prepared material was improved with increasing amounts of residual carbon, in particular, LTO/C including 6.2 wt.% residual carbon exhibited the best electrode performance of 156 mAh g-1 at 1 C during 50 cyclings when compared to the other materials.

  19. Fabrication and characterization of TiO2-NTs based hollow carbon fibers/carbon film composite electrode with NiOx decorated for capacitive application

    Science.gov (United States)

    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.

  20. Polymer-Derived Ceramic Functionalized MoS2 Composite Paper as a Stable Lithium-Ion Battery Electrode

    Science.gov (United States)

    David, L.; Bhandavat, R.; Barrera, U.; Singh, G.

    2015-04-01

    A facile process is demonstrated for the synthesis of layered SiCN-MoS2 structure via pyrolysis of polysilazane functionalized MoS2 flakes. The layered morphology and polymer to ceramic transformation on MoS2 surfaces was confirmed by use of electron microscopy and spectroscopic techniques. Tested as thick film electrode in a Li-ion battery half-cell, SiCN-MoS2 showed the classical three-stage reaction with improved cycling stability and capacity retention than neat MoS2. Contribution of conversion reaction of Li/MoS2 system on overall capacity was marginally affected by the presence of SiCN while Li-irreversibility arising from electrolyte decomposition was greatly suppressed. This is understood as one of the reasons for decreased first cycle loss and increased capacity retention. SiCN-MoS2 in the form of self-supporting paper electrode (at 6 mg.cm-2) exhibited even better performance, regaining initial charge capacity of approximately 530 mAh.g-1 when the current density returned to 100 mA.g-1 after continuous cycling at 2400 mA.g-1 (192 mAh.g-1). MoS2 cycled electrode showed mud-cracks and film delamination whereas SiCN-MoS2 electrodes were intact and covered with a uniform solid electrolyte interphase coating. Taken together, our results suggest that molecular level interfacing with precursor-derived SiCN is an effective strategy for suppressing the metal-sulfide/electrolyte degradation reaction at low discharge potentials.

  1. Thermally stable single-atom platinum-on-ceria catalysts via atom trapping.

    Science.gov (United States)

    Jones, John; Xiong, Haifeng; DeLaRiva, Andrew T; Peterson, Eric J; Pham, Hien; Challa, Sivakumar R; Qi, Gongshin; Oh, Se; Wiebenga, Michelle H; Pereira Hernández, Xavier Isidro; Wang, Yong; Datye, Abhaya K

    2016-07-01

    Catalysts based on single atoms of scarce precious metals can lead to more efficient use through enhanced reactivity and selectivity. However, single atoms on catalyst supports can be mobile and aggregate into nanoparticles when heated at elevated temperatures. High temperatures are detrimental to catalyst performance unless these mobile atoms can be trapped. We used ceria powders having similar surface areas but different exposed surface facets. When mixed with a platinum/aluminum oxide catalyst and aged in air at 800°C, the platinum transferred to the ceria and was trapped. Polyhedral ceria and nanorods were more effective than ceria cubes at anchoring the platinum. Performing synthesis at high temperatures ensures that only the most stable binding sites are occupied, yielding a sinter-resistant, atomically dispersed catalyst. PMID:27387946

  2. Thermally stable single-atom platinum-on-ceria catalysts via atom trapping

    Energy Technology Data Exchange (ETDEWEB)

    Jones, John; Xiong, Haifeng; DelaRiva, Andrew; Peterson, Eric J.; Pham, Hien; Challa, Sivakumar R.; Qi, Gongshin; Oh, Se H.; Wiebenga, Michelle H.; Pereira Hernandez, Xavier I.; Wang, Yong; Datye, Abhaya K.

    2016-07-08

    Catalysts based on single atoms of scarce precious metals can lead to more efficient use through enhanced reactivity and selectivity. However, single atoms on catalyst supports can be mobile and aggregate into nanoparticles when heated at elevated temperatures. High temperatures are detrimental to catalyst performance unless these mobile atoms can be trapped. We used ceria powders having similar surface areas but different exposed surface facets. When mixed with a platinum/ aluminum oxide catalyst and aged in air at 800°C, the platinum transferred to the ceria and was trapped. Polyhedral ceria and nanorods were more effective than ceria cubes at anchoring the platinum. Performing synthesis at high temperatures ensures that only the most stable binding sites are occupied, yielding a sinter-resistant, atomically dispersed catalyst.

  3. Nanostructured PLD-grown gadolinia doped ceria: Chemical and structural characterization by transmission electron microscopy techniques

    DEFF Research Database (Denmark)

    Rodrigo, Katarzyna Agnieszka; Wang, Hsiang-Jen; Heiroth, Sebastian;

    2011-01-01

    The morphology as well as the spatially resolved elemental and chemical characterization of 10 mol% gadolinia doped ceria (CGO10) structures prepared by pulsed laser deposition (PLD) technique are investigated by scanning transmission electron microscopy accompanied with electron energy loss...

  4. Imaging space charge regions in Sm-doped ceria using electrochemical strain microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qian Nataly; Li, Jiangyu, E-mail: jjli@uw.edu [Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States); Adler, Stuart B., E-mail: stuadler@uw.edu [Department of Chemical Engineering, University of Washington, Seattle, Washington 98195 (United States)

    2014-11-17

    Nanocrystalline ceria exhibits a total conductivity several orders of magnitude higher than microcrystalline ceria in air at high temperature. The most widely accepted theory for this enhancement (based on fitting of conductivity data to various transport and kinetic models) is that relatively immobile positively charged defects and/or impurities accumulate at the grain boundary core, leading to a counterbalancing increase in the number of mobile electrons (small polarons) within a diffuse space charge region adjacent to each grain boundary. In an effort to validate this model, we have applied electrochemical strain microscopy to image the location and relative population of mobile electrons near grain boundaries in polycrystalline Sm-doped ceria in air at 20–200 °C. Our results show the first direct (spatially resolved) evidence that such a diffuse space charge region does exist in ceria, and is localized to both grain boundaries and the gas-exposed surface.

  5. Ceria-Modified Clay Supported Palladium Catalysts for Complete Oxidation of Volatile Organic Compounds

    Institute of Scientific and Technical Information of China (English)

    Li Jinjun; Hao Zhengping; Hu Chun

    2004-01-01

    Ceria- and alumina-pillared interlayered clays were synthesized in the presence of PEO surfactant by using laponite clay as raw material.And the synthesized pillared clays were used as supports to load palladium catalysts for complete oxidation of benzene.Nitrogen adsorption/desorption experiments reveal that the pillared clays have higher tests show that ceria pillar exhibited promoting effect on the activity of the palladium catalysts, and ceria-pillared clay supported palladium catalyst catalyzed the complete oxidation of benzene at less than 250 ℃.The calcination temperature affects the activity of the catalysts significantly, and it is found that the optimal calcination temperature are 600 and 400 ℃ for ceria- and alumina-pillared clay supported palladium catalysts, respectively.

  6. Reducibility of ceria-lanthana mixed oxides under temperature programmed hydrogen and inert gas flow conditions

    International Nuclear Information System (INIS)

    The present paper deals with the preparation and characterization of La/Ce mixed oxides, with La molar contents of 20, 36 and 57%. We carry out the study of the structural, textural and redox properties of the mixed oxides, comparing our results with those for pure ceria. For this aim we use temperature programmed reduction (TPR), temperature programmed desorption (TPD), nitrogen physisorption at 77 K, X-ray diffraction and high resolution electron microscopy. The mixed oxides are more easy to reduce in a flow of hydrogen than ceria. Moreover, in an inert gas flow they release oxygen in higher amounts and at lower temperatures than pure CeO2. The textural stability of the mixed oxides is also improved by incorporation of lanthana. All these properties make the ceria-lanthana mixed oxides interesting alternative candidates to substitute ceria in three-way catalyst formulations. (orig.)

  7. Understanding the solar-driven reduction of CO2 on doped ceria

    OpenAIRE

    Ramos-Fernandez, E.V.; Shiju, N.R.; Rothenberg, G.

    2014-01-01

    With the appropriate materials, one can construct redox cycles that use CO2 as the oxidant, generating CO as the product. Here, we investigate thermochemical cycles using doped ceria compounds as the oxygen exchange medium. Doped samples are prepared using La, Cr, W, Zr, V, Y, and Ti as dopants. Studying the redox kinetics, we show that doping the pure ceria with zirconium strongly increases overall CO production, albeit at lower reaction rates. This is because the CO2 reduction step is secon...

  8. Lattice Constant Dependence on Particle Size for Ceria prepared from a Citrate Sol-Gel

    Science.gov (United States)

    Morris, V. N.; Farrell, R. A.; Sexton, A. M.; Morris, M. A.

    2006-02-01

    High surface area ceria nanoparticles have been prepared using a citrate solgel precipitation method. Changes to the particle size have been made by calcining the ceria powders at different temperatures, and X-ray methods used to determine their lattice parameters. The particle sizes have been assessed using transmission electron microscopy (TEM) and the lattice parameter found to fall with decreasing particle size. The results are discussed in the light of the role played by surface tension effects.

  9. Viscoelastic properties of doped-ceria under reduced oxygen partial pressure

    DEFF Research Database (Denmark)

    Teocoli, Francesca; Esposito, Vincenzo

    2014-01-01

    The viscoelastic properties of gadolinium-doped ceria (CGO) powder compacts are characterized during sintering and cooling under reduced oxygen partial pressure and compared with conventional sintering in air. Highly defective doped ceria in reducing conditions shows peculiar viscoelastic...... properties due to fast mass diffusion phenomena activated at low temperatures by Ce4+ to Ce3+ reduction. Particularly, the viscous behavior is affected by dramatic microstructural changes, fast grain growth and densification, which are rapidly completed in the last stage of sintering....

  10. Effective Heat and Mass Transport Properties of Anisotropic Porous Ceria for Solar Thermochemical Fuel Generation

    OpenAIRE

    Sophia Haussener; Aldo Steinfeld

    2012-01-01

    High-resolution X-ray computed tomography is employed to obtain the exact 3D geometrical configuration of porous anisotropic ceria applied in solar-driven thermochemical cycles for splitting H2O and CO2. The tomography data are, in turn, used in direct pore-level numerical simulations for determining the morphological and effective heat/mass transport properties of porous ceria, namely: porosity, specific surface area, pore size distribution, extinction coefficient, thermal conductivity, conv...

  11. Enhanced photoelectrochemical water splitting from Si quantum dots/TiO{sub 2} nanotube arrays composite electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhong [Department of Materials Science, Fudan University, Shanghai 200433 (China); Cui, Xiaoli, E-mail: xiaolicui@fudan.edu.cn [Department of Materials Science, Fudan University, Shanghai 200433 (China); Hao, Hongchen; Lu, Ming [Department of Optical Science and Engineering, and Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Fudan University, Shanghai 200433 (China); Lin, Yuehe [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164-2920 (United States)

    2015-06-15

    Graphical abstract: Si quantum dots were firstly applied to modify TiO{sub 2} nanotubes and enhanced visible light response was demonstrated for the resulted Si QDs/TiO{sub 2} nanocomposite. Si QDs are promising in photoelectrochemical water splitting and photocatalysis since their low cost, abundance and environmentally-friendliness. - Highlights: • A novel nanocomposite Si QDs/TiO{sub 2} nanotubes was fabricated and characterized. • Enhanced photoelectrochemical water splitting was firstly demonstrated for Si QDs/TiO{sub 2}. • The visible light response of TiO{sub 2} increased with the presence of Si QDs. - Abstract: This work firstly introduced Si quantum dots (QDs) to modify TiO{sub 2} nanotube arrays for photoelectrochemical water splitting. A systematic study using surface and optical characterization tools reveals the nature of the combination of Si QDs and TiO{sub 2} nanotube arrays. Scanning electron microscopy and X-ray photoelectron spectroscopy results show that Si QDs were assembled on the surface of vertically aligned TiO{sub 2} nanotube arrays. The UV–vis diffuse reflectance spectra indicate the improved visible light absorbance. The enhanced photoelectrochemical water splitting was demonstrated under visible light illumination and the photocurrent density was 1.6 times larger than that of pristine TiO{sub 2} electrodes. Electrochemical impedance behavior was measured for the electrodes and the impedance is slightly reduced for the nanocomposite electrode with the presence of Si QDs. This work demonstrated that Si QDs would be a novel and effective choice for improving the utilization of visible light for TiO{sub 2} nanotubes.

  12. Adhesion and Atomic Structures of Gold on Ceria Nanostructures:The Role of Surface Structure and Oxidation State of Ceria Supports

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yuyuan [Northwestern University, Evanston; Wu, Zili [ORNL; Wen, Jianguo [Argonne National Laboratory (ANL); Poeppelmeier, Kenneth R [Northwestern University, Evanston; Marks, Laurence D [Northwestern University, Evanston

    2015-01-01

    Recent advances in heterogeneous catalysis have demonstrated that oxides supports with the same material but different shapes can result in metal catalysts with distinct catalytic properties. The shape-dependent catalysis was not well-understood owing to the lack of direct visualization of the atomic structures at metal-oxide interface. Herein, we utilized aberration-corrected electron microscopy and revealed the atomic structures of gold particles deposited on ceria nanocubes and nanorods with {100} or {111} facets exposed. For the ceria nanocube support, gold nanoparticles have extended atom layers at the metal-support interface. In contrast, regular gold nanoparticles and rafts are present on the ceria nanorod support. After hours of water gas shift reaction, the extended gold atom layers and rafts vanish, which is associated with the decrease of the catalytic activities. By understanding the atomic structures of the support surfaces, metal-support interfaces, and morphologies of the gold particles, a direct structure-property relationship is established.

  13. Nano-sized ceria particles prepared by spray pyrolysis using polymeric precursor solution

    International Nuclear Information System (INIS)

    Nano-sized ceria particles were prepared from the aqueous solution containing the polymeric precursors by ultrasonic spray pyrolysis at the severe preparation conditions such as high flow rate of carrier gas and short residence time. The key idea to produce nanoparticles was to prepare hollow ceria particles which are easily turned to aggregates of nano-sized primary particles during the post-thermal treatment and thereafter disintegrate such aggregates to nano-sized particles by a simple ball milling process. It was found that using the polymeric precursor strongly influences the crystallization characteristics and morphological changes of the as-prepared particles during the post-thermal treatment. The as-prepared particles prepared from the polymeric precursor solution had non-spherical shape and fractured structure with a thin shell, whereas the as-prepared and calcined ceria particles obtained from the aqueous solution had spherical shape and hollow morphology with a thick shell. Also, nano-sized ceria particles prepared from the polymeric precursor solution had less aggregated structure than those prepared from the aqueous solution. For the ceria particles prepared from the polymeric precursor solution, the degree of aggregation between the primary particles was reduced as increasing the calcination temperature. As a result, aggregation-free nano-sized ceria particles were obtained above 1200 deg. C without a milling process. The mean size of the primary particles increased from several tens nanometer to submicrometer size as the calcination temperature changed from 800 to 1300 deg. C

  14. Monodisperse ceria nanospheres: Synthesis, characterization, optical properties, and applications in wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Li Jie [Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Kalam, Abul; Al-Shihri, Ayed Sad [Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413, P.O. Box 9004 (Saudi Arabia); Su Qingmei; Zhong Guo [Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 (China); Du Gaohui, E-mail: gaohuidu@zjnu.cn [Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004 (China)

    2011-11-01

    Monodisperse ceria nanospheres have been synthesized by a facile solvothermal method, and their morphology and microstructures have been revealed by a combination of X-ray diffraction (XRD), scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy and N{sub 2} adsorption. It is demonstrated that the as-synthesized powders are highly uniform CeO{sub 2} in spherical shape with cubic fluorite structure. HRTEM and XRD studies show that each ceria nanosphere is composed of dozens of nanocrystals with the average size of 8.5 nm. The direct optical band gap of the ceria nanospheres estimated from the ultraviolet-visible absorption spectrum is 2.7 eV, which is evidently red-shifted with respect to the bulk material (E{sub g} = 3.19 eV); the reduced band gap could be resulted from the high concentration of grain boundaries and defects present in the ceria nanospheres. In addition, the ceria nanospheres exhibit a strong blue luminescence at 504 nm and a broad orange luminescence centered at 645 nm. As a result of the large specific surface area, ceria nanospheres are revealed to be an excellent sorbent for the removal of poisonous pollutants present in water, such as chromium ions and rhodamine B. The removal efficiency of chromium ions is as high as {approx}94%.

  15. Characterization of gadolinia doped ceria prepared with nanostructured powders

    International Nuclear Information System (INIS)

    Gadolinia doped ceria is a potential material for application as solid electrolyte in solid oxide fuel cells that operate at intermediate temperatures. The performance of this kind of device is strongly influenced by the properties of the solid electrolyte, and then, by its microstructure. In this work the microstructure evolution of materials with surface area between 7 and 200 m2/g was investigated in detail. Cylindrical pellets were prepared by isostatic compaction and sintered in the 700 deg C to 1400 deg C temperature range. X-ray diffraction experiments were conducted to follow the crystallite growth. The microstructure evolution was accompanied by scanning electron microscopy. The densification was estimated by the geometric parameters of the samples and by dilatometry. The results revealed a fast sintering kinetics for materials with finer particle size, as expected. Different behaviors for crystallite growth were verified. (author)

  16. Morphological Control and Characterization of Monodispersed Ceria Particles

    International Nuclear Information System (INIS)

    The morphological control of cerium oxide particles was carried out by a homogeneous precipitation followed by calcination in air at 400 deg. C. The effects of pre-aging temperature, aging time and precipitation reagents on the morphologies of final products were investigated. When urea was used as a precipitation reagent, monodispersed spherical and flake-like cerium carbonate hydroxide precursor was precipitated in the solution at 90 deg. C for 2 h after pre-aging at 25 deg. C - 50 deg. C for 24-72 h. On the other hand, monodispersed nanosize rod-like cerium hydroxide particles were obtained using triethanolamine as precipitation reagent. Ceria particles with the same morphologies and slightly smaller particle size than those of as-prepared cerium precursor could be obtained after calcination in air at 400 deg. C. Physical-chemical characteristics of the monodispersed cerium oxide particles were evaluated.

  17. Comparative structural and optical properties of different ceria nanoparticles.

    Science.gov (United States)

    Nikolic, A S; Boskovic, M; Fabian, M; Bozanic, D K; Vucinic-Vasic, M; Kremenovic, A; Antic, B

    2013-10-01

    Herein a comparative study of five nanocrystalline cerium oxides (CeO(2-delta)) synthesised by different methods and calcined at 500 degrees C is reported. XRPD analysis showed that stoichiometry parameter delta, crystallite size/strain and lattice constant were only slightly affected by the method utilized. All ceria nanoparticles are nearly spherical in shape with faceted morphology, free of defects and with a relatively uniform size distribution. The average microstrain was found to be approximately 10 times higher than that of bulk counterpart. The absorption edge of nanocrystalline materials was shifted towards a higher wavelengths (red shift) in comparison with bulk counterpart, and band gap values were in the range 2.7-3.24 eV (3.33 eV for bulk counterpart). PMID:24245144

  18. Binder-free nitrogen-doped carbon paper electrodes derived from polypyrrole/cellulose composite for Li-O2 batteries

    Science.gov (United States)

    Liu, Jia; Wang, Zhaohui; Zhu, Jiefang

    2016-02-01

    This work presents a novel binder-free nitrogen-doped carbon paper electrode (NCPE), which was derived from a N-rich polypyrrole (PPy)/cellulose-chopped carbon filaments (CCFs) composite, for Li-O2 batteries. The fabrication of NCPE involved cheap raw materials (e.g., Cladophora sp. green algae) and easy operation (e.g., doping N by a carbonization of N-rich polymer), which is especially suitable for large-scale production. The NCPE exhibited a bird's nest microstructure, which could provide the self-standing electrode with considerable mechanic durability, fast Li+ and O2 diffusion, and enough space for the discharge product deposition. In addition, the NCPE contained N-containing function groups, which may promote the electrochemical reactions. Furthermore, binder-free architecture designs can prevent binder-involved parasitic reactions. A Li-O2 cell with the NCPE displayed a cyclability of more than 30 cycles at a constant current density of 0.1 mA/cm2. The 1st discharge capacity for a cell with the NCPE reached 8040 mAh/g at a current density of 0.1 mA/cm2, with a cell voltage around 2.81 V. A cell with the NCPE displayed a coulombic efficiency of 81% on the 1st cycle at a current density of 0.2 mA/cm2. These results represent a promising progress in the development of a low-cost and versatile paper-based O2 electrode for Li-O2 batteries.

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

    Science.gov (United States)

    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

  20. 14.7% efficient mesoscopic perovskite solar cells using single walled carbon nanotubes/carbon composite counter electrodes

    Science.gov (United States)

    Li, Hao; Cao, Kun; Cui, Jin; Liu, Shuangshuang; Qiao, Xianfeng; Shen, Yan; Wang, Mingkui

    2016-03-01

    A single walled carbon nanotube (SWCNT) possesses excellent hole conductivity. This work communicates an investigation of perovskite solar cells using a mesoscopic TiO2/Al2O3 structure as a framework in combination with a certain amount of SWCNT-doped graphite/carbon black counter electrode material. The CH3NH3PbI3-based device achieves a power conversion efficiency of 14.7% under AM 1.5G illumination. Detailed investigations show an increased charge collection in this device compared to that without the SWCNT additive.A single walled carbon nanotube (SWCNT) possesses excellent hole conductivity. This work communicates an investigation of perovskite solar cells using a mesoscopic TiO2/Al2O3 structure as a framework in combination with a certain amount of SWCNT-doped graphite/carbon black counter electrode material. The CH3NH3PbI3-based device achieves a power conversion efficiency of 14.7% under AM 1.5G illumination. Detailed investigations show an increased charge collection in this device compared to that without the SWCNT additive. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07347b

  1. Nonenzymatic L-lysine amino acid detection using titanium oxide nanoparticles/multi wall carbon nanotube composite electrodes

    International Nuclear Information System (INIS)

    Graphical abstract: - Abstract: For the first time, a nonenzymatic electrochemical sensor for the detection of lysine was proposed based on immobilizing Multi wall carbon nanotube (MWCNT) and Titanium oxide nanoparticles (TiO2NPs) on glassy carbon (GC) electrode. Scaning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) were used to confirm the successful stepwise assembly procedure of the sensor. The electrocatalytical behaviors of the sensor were also investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results showed that MWCNT- TiO2NPs exhibited a remarkable electrocatalytic activity for the oxidation of lysine. Under optimal conditions, the DPV response of the sensor was proportional to the lysine concentration in the range of 500 to 5500 nanomolar with a detection limit and sensitivity of 390 nM and 0.1795 μAμM−1. This electrode show many advantages such as simple preparation without using any enzyme special electron transfer mediator or specific reagent, excellent catalytic activity at physiological pH values and antifouling property toward lysine and its oxidation product. Furthermore, the selectivity of the proposed sensor was tested in the presence of some amino acids and the response of the sensor was encountered with interferences of proline and tryptophan at equimolar concentrations

  2. Ethanol Oxidation Reaction Using PtSn/C+Ce/C Electrocatalysts: Aspects of Ceria Contribution

    International Nuclear Information System (INIS)

    The ethanol oxidation reaction (EOR) was investigated using PtSn/C + Ce/C electrocatalysts in different mass ratios (58:42, 53:47, and 42:58) prepared using the polymeric precursor method. Transmission electron microscopy (TEM) experiments showed particles sizes in the range of 3 to 7 nm. Changes in the net parameters observed for Pt suggest the incorporation of Sn into the Pt crystalline network with the formation of an alloy mixture with the SnO2 phase. Among the PtSn/C + Ce/C catalysts investigated, the 53:47 composition showed the highest activity towards the EOR. In this case, the j versus t curves obtained in the presence of ethanol in acidic media exhibited a current density 90% higher than that observed with the commercial PtSn/C (ETEK). Correspondingly, during the experiments performed on single direct ethanol fuel cells, the maximum power density obtained using PtSn/C + Ce/C (53:47) as the anode was approximately 60% higher than that obtained using the commercial catalyst. FTIR data showed that the observed behavior for ethanol oxidation may be explained in terms of a synergic effect of bifunctional mechanism with electronic effects, in addition to a chemical effect of ceria that provides oxygen-containing species to oxidize acetaldehyde to acetic acid

  3. Regenerable ceria-based SOx traps for sulfur removal in lean exhausts

    International Nuclear Information System (INIS)

    Bare and Pt-containing CeO2, Al2O3:MgO mixed oxide and Al2O3 have been investigated as potential regenerable sulfur oxides (SOx) traps. The samples were evaluated by lean SOx adsorption and temperature programmed desorption using synthetic gas compositions. In addition, combined DRIFT spectroscopy and mass spectrometry were employed to obtain mechanistic information on the adsorption of SOx. The results suggest Pt/CeO2 as promising SOx trap material owing to a high storage capacity at 250 C in combination with efficient release above 600 C. The presence of Pt is generally found to enhance the lean SOx storage capacity at 250 C for CeO2-based samples. Lean SO2 adsorption on CeO2 is found to proceed via the formation of surface and bulk sulfates, where the latter is formed more rapidly for the Pt-containing CeO2 sample. Ceria samples pre-exposed to high amounts of SO2 at 250 and 400 C show lower SOx storage capacity and higher SOx release as compared to fresh samples. This indicates that under the conditions used in this study, a part of the storage sites on CeO2 are non-regenerable. (author)

  4. Hierarchically oriented macroporous anode-supported solid oxide fuel cell with thin ceria electrolyte film.

    Science.gov (United States)

    Chen, Yu; Zhang, Yanxiang; Baker, Jeffrey; Majumdar, Prasun; Yang, Zhibin; Han, Minfang; Chen, Fanglin

    2014-04-01

    Application of anode-supported solid oxide fuel cell (SOFC) with ceria based electrolyte has often been limited by high cost of electrolyte film fabrication and high electrode polarization. In this study, dense Gd0.1Ce0.9O2 (GDC) thin film electrolytes have been fabricated on hierarchically oriented macroporous NiO-GDC anodes by a combination of freeze-drying tape-casting of the NiO-GDC anode, drop-coating GDC slurry on NiO-GDC anode, and co-firing the electrolyte/anode bilayers. Using 3D X-ray microscopy and subsequent analysis, it has been determined that the NiO-GDC anode substrates have a porosity of around 42% and channel size from around 10 μm at the electrolyte side to around 20 μm at the other side of the NiO-GDC (away from the electrolyte), indicating a hierarchically oriented macroporous NiO-GDC microstructure. Such NiO-GDC microstructure shows a tortuosity factor of ∼1.3 along the thickness direction, expecting to facilitate gas diffusion in the anode during fuel cell operation. SOFCs with such Ni-GDC anode, GDC film (30 μm) electrolyte, and La0.6Sr0.4Co0.2Fe0.8O3-GDC (LSCF-GDC) cathode show significantly enhanced cell power output of 1.021 W cm(-2) at 600 °C using H2 as fuel and ambient air as oxidant. Electrochemical Impedance Spectroscopy (EIS) analysis indicates a decrease in both activation and concentration polarizations. This study has demonstrated that freeze-drying tape-casting is a very promising approach to fabricate hierarchically oriented porous substrate for SOFC and other applications. PMID:24621230

  5. An electrochemical sensor for warfarin determination based on covalent immobilization of quantum dots onto carboxylated multiwalled carbon nanotubes and chitosan composite film modified electrode

    International Nuclear Information System (INIS)

    A method is described for the construction of a novel electrochemical warfarin sensor based on covalent immobilization of CdS-quantum dots (CdS-QDs) onto carboxylated multiwalled carbon nanotubes/chitosan (CS) composite film on the surface of a glassy carbon electrode. The CdS-QDs/CS/MWCNTs were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, XRD analysis and electrochemical impedance spectroscopy (EIS). The sensor showed optimum anodic stripping response within 90 s at an accumulation potential of 0.75 V. The modified electrode was used to detect the concentration of warfarin with a wide linear range of 0.05–80 μM and a detection limit (S/N = 3) of 8.5 nM. The proposed sensor has good storage stability, repeatability and reproducibility and was successfully applied for the determination of warfarin in real samples such as urine, serum and milk. - Highlights: • A new sensitive sensor for warfarin determination was developed. • The sensor was constructed based on covalent immobilization of CdS-QDs on the chitosan/MWCNTs/GCE. • The parameters affecting the stripping analysis of warfarin were optimized. • The proposed sensor is used for trace determination of warfarin in urine, serum and milk

  6. Optimisation of the composition of a screen-printed acrylate polymer enzyme layer with respect to an improved selectivity and stability of enzyme electrodes.

    Science.gov (United States)

    Mersal, G A M; Khodari, M; Bilitewski, U

    2004-09-15

    Glucose oxidase (GOD) was immobilized on screen-printed platinum electrodes by entrapment in a screen printable paste polymerized by irradiation with UV-light. The influences of different additives, in particular polymers and graphite, on the sensitivity and stability of the sensor and the permeability of the enzyme layer for a possible electrochemical interferent were investigated. The chosen additives were Gafquat 755N, poly-L-lysine, bovine serum albumin (BSA), sodium dodecylsulfate (SDS), polyethylene glycol (PEG), Nafion and graphite. All additives led to increases of glucose signals, i.e. improved the sensitivity of glucose detection with Gafquat 755N, poly-L-lysine, SDS and graphite showing the strongest influences with increases by a factor 4, 6.5, 5 and 10, respectively. Ascorbic acid was used as a model interferent showing the influence of the enzyme layer composition on the selectivity of the sensor. The addition of Gafquat 755N or poly-L-lysine led to higher signals not only for glucose, but also for ascorbic acid. SDS addition already reduced the influence of ascorbic acid, which was almost completely eliminated when Nafion (5%) and PEG (10%) were added. A comparable beneficial effect on the selectivity of the sensors was also observed for the addition of 0.5% graphite. Thus, the enzyme electrodes with PEG, Nafion or graphite as additives in the enzyme layer were applied to glucose determinations in food samples and samples obtained from E. coli cultivations. PMID:15308235

  7. Selective and sensitive determination of uric acid in the presence of ascorbic acid and dopamine by PDDA functionalized graphene/graphite composite electrode.

    Science.gov (United States)

    Yu, Yanyan; Chen, Zuanguang; Zhang, Beibei; Li, Xinchun; Pan, Jianbin

    2013-08-15

    In this work, a facile electrochemical sensor based on poly(diallyldimethylammonium chloride) (PDDA) functionalized graphene (PDDA-G) and graphite was fabricated. The composite electrode exhibited excellent selectivity and sensitivity towards uric acid (UA), owing to the electrocatalytic effect of graphene nanosheets and the electrostatic attractions between PDDA-G and UA. The anodic peak current of UA obtained by cyclic voltammetry (CV) increased over 10-fold compared with bare carbon paste electrode (CPE). And the reversibility of the oxidation process was improved significantly. Differential pulse voltammetry (DPV) was used to determine UA in the presence of ascorbic acid (AA) and dopamine (DA). It was found that all of oxidation peaks of three species could be well resolved, and the peak current of UA was much stronger than the other two components. More importantly, considerable-amount of AA and DA showed negligible interference to UA assay. The calibration curve for UA ranged from 0.5 to 20 μmol L(-1) with a correlation coefficient of 0.9934. The constructed sensor has been employed to quantitatively determine UA in urine samples. PMID:23708533

  8. Simultaneous detection of ascorbic acid, dopamine, uric acid and tryptophan with Azure A-interlinked multi-walled carbon nanotube/gold nanoparticles composite modified electrode

    Directory of Open Access Journals (Sweden)

    Hayati Filik

    2016-05-01

    Full Text Available In this paper, multi-walled carbon nanotube/Azure A/gold nanoparticle composites (Nafion/AuNPs/AzA/MWCNTs were prepared by binding gold nanoparticles to the surfaces of Azure A-coated carbon nanotubes. Nafion/AuNPs/AzA/MWCNTs based electrochemical sensor was fabricated for the simultaneous determination of ascorbic acid, dopamine, uric acid, and tryptophan. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the electrochemical properties of the modified electrodes. The modified electrode showed excellent electrocatalytic activity toward ascorbic acid, dopamine, uric acid, and tryptophan (pH 7.0. The experiment results showed that the linear response range for simultaneous detection of AA, DA, UA and Trp were 300–10,000 μM, 0.5–50 μM, 0.5–50 μM and 1.0–100 μM, respectively, and the detection limits were 16 μM, 0.014 μM, 0.028 μM and 0.56 μM (S/N = 3. The proposed method offers promise for simple, rapid, selective and cost-effective analysis of small biomolecules. The procedure was also applied to the determination of tryptophan in spiked milk samples.

  9. Optimization of TiO2/Cu/TiO2 multilayers as a transparent composite electrode deposited by electron-beam evaporation at room temperature

    Institute of Scientific and Technical Information of China (English)

    孙洪涛; 王小平; 寇志起; 王丽军; 王金烨; 孙义清

    2015-01-01

    Highly transparent indium-free composite electrodes of TiO2/Cu/TiO2 are deposited by electron-beam evaporation at room temperature. The effects of Cu thickness and annealing temperature on the electrical and optical properties of the multilayer film are investigated. The critical thickness of Cu mid-layer to form a continuous conducting layer is found to be 11 nm. The multilayer with a mid-Cu thickness of 11 nm is optimized to obtain a resistivity of 7.4×10−5 Ω·cm and an average optical transmittance of 86%in the visible spectral range. The figure of merit of the TiO2/Cu(11 nm)/TiO2 multilayer annealed at 150 ◦C reaches a minimum resistivity of 5.9×10−5 Ω·cm and an average optical transmittance of 88%in the visible spectral range. The experimental results indicate that TiO2/Cu/TiO2 multilayers can be used as a transparent electrode for solar cell and other display applications.

  10. An electrochemical sensor for warfarin determination based on covalent immobilization of quantum dots onto carboxylated multiwalled carbon nanotubes and chitosan composite film modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Gholivand, Mohammad Bagher, E-mail: mbgholivand2013@gmail.com; Mohammadi-Behzad, Leila

    2015-12-01

    A method is described for the construction of a novel electrochemical warfarin sensor based on covalent immobilization of CdS-quantum dots (CdS-QDs) onto carboxylated multiwalled carbon nanotubes/chitosan (CS) composite film on the surface of a glassy carbon electrode. The CdS-QDs/CS/MWCNTs were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, XRD analysis and electrochemical impedance spectroscopy (EIS). The sensor showed optimum anodic stripping response within 90 s at an accumulation potential of 0.75 V. The modified electrode was used to detect the concentration of warfarin with a wide linear range of 0.05–80 μM and a detection limit (S/N = 3) of 8.5 nM. The proposed sensor has good storage stability, repeatability and reproducibility and was successfully applied for the determination of warfarin in real samples such as urine, serum and milk. - Highlights: • A new sensitive sensor for warfarin determination was developed. • The sensor was constructed based on covalent immobilization of CdS-QDs on the chitosan/MWCNTs/GCE. • The parameters affecting the stripping analysis of warfarin were optimized. • The proposed sensor is used for trace determination of warfarin in urine, serum and milk.

  11. RuO{sub 2}.xH{sub 2}O/NiO composites as electrodes for electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Pico, Fernando [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, c/Sor Juana Ines de la Cruz 3, E-28049 Madrid (Spain); Ibanez, Joaquin [Centro Nacional de Investigaciones Metalurgicas, CSIC, Av. Gregorio del Amo 8, E-28040 Madrid (Spain); Centeno, Teresa A. [Instituto Nacional del Carbon, CSIC, c/Francisco Pintado Fe 26, Apartado 73, E-33080 Oviedo (Spain); Pecharroman, Carlos [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, c/Sor Juana Ines de la Cruz 3, E-28049 Madrid (Spain); Rojas, Rosa M. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, c/Sor Juana Ines de la Cruz 3, E-28049 Madrid (Spain); Amarilla, Jose M. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, c/Sor Juana Ines de la Cruz 3, E-28049 Madrid (Spain); Rojo, Jose M. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, c/Sor Juana Ines de la Cruz 3, E-28049 Madrid (Spain)]. E-mail: jmrojo@icmm.csic.es

    2006-06-05

    RuO{sub 2}.xH{sub 2}O/NiO composites having RuO{sub 2} contents in the range 0-100 wt.% have been prepared by a co-precipitation method. Structural, microstructural and textural transformations after heating the as-prepared composites at 200 and 600 deg. C have been followed by X-ray diffraction, scanning electron microscopy (SEM) and nitrogen adsorption/desorption isotherms. At 200 deg. C the composites are made of micrometric particles in which nanometric crystallites of the two oxides are aggregated. The composites show microporosity (0.02-0.10 cm{sup 3}/g), mesoporosity (0.07-0.12 cm{sup 3}/g) and relatively high specific surface area (62-309 m{sup 2}/g). At 600 deg. C the composites are fully dehydrated and RuO{sub 2} has crystallized and segregated. Microporosity and mesoporosity as well as specific surface area are strongly decreased. Specific capacitance and specific surface area of the composites heated at 200 and 600 deg. C have been measured and discussed on the basis of the RuO{sub 2} content. For comparison the specific capacitance and specific surface area of mixtures of NiO and RuO{sub 2}.xH{sub 2}O (or RuO{sub 2}) have been taken as references. The higher specific capacitance of the 200 deg. C-heated composites compared to the 600 deg. C-heated ones is due to the higher specific surface area of the former and the higher pseudocapacitance of RuO{sub 2}.xH{sub 2}O compared to RuO{sub 2}. The discussion reported in this work can be applied to other composites such as RuO{sub 2}.xH{sub 2}O/carbon and RuO{sub 2}.xH{sub 2}O/other oxides.

  12. Comparison of Electrodes for High-Performance Electrochemical Capacitors: Multi-Layer MnO2/Pt and Composite MnO2/Pt on Carbon Nanofibres.

    Science.gov (United States)

    Lee, Yu-Jin; An, Geon-Hyoung; Ahn, Hyo-Jin

    2015-11-01

    Four different types of electrodes for high-performance electrochemical capacitors were prepared using electrospinning method and/or impregnation methods: (1) conventional carbon nanofibres (CNF) supports, and CNFs decorated with (2) MnO2 nanophases, (3) multi-layer MnO2/Pt nanophases, and (4) composite MnO2 and Pt nanophases. Their morphological, structural, chemical, and electrochemical properties were characterized using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and galvanostatic charge/discharge measurements. Composite MnO2 and Pt nanophases decorated on the CNFs exhibited superior capacitance (-252.3 F/g at 10 mV/s), excellent capacitance retention (-93.5% after 300 cycles), and high energy densities (13.53-18.06 Wh/kg). The enhanced electrochemical performances can be explained by the composite structure, presenting well-dispersed MnO2 nanophases leading to high capacitance, and well-dispersed Pt nanophases leading to improved electrical conductivity. PMID:26726621

  13. Hybrid nanostructured microporous carbon-mesoporous carbon doped titanium dioxide/sulfur composite positive electrode materials for rechargeable lithium-sulfur batteries

    Science.gov (United States)

    Zegeye, Tilahun Awoke; Kuo, Chung-Feng Jeffrey; Wotango, Aselefech Sorsa; Pan, Chun-Jern; Chen, Hung-Ming; Haregewoin, Atetegeb Meazah; Cheng, Ju-Hsiang; Su, Wei-Nien; Hwang, Bing-Joe

    2016-08-01

    Herein, we design hybrid nanostructured microporous carbon-mesoporous carbon doped titanium dioxide/sulfur composite (MC-Meso C-doped TiO2/S) as a positive electrode material for lithium-sulfur batteries. The hybrid MC-Meso C-doped TiO2 host material is produced by a low-cost, hydrothermal and annealing process. The resulting conductive material shows dual microporous and mesoporous behavior which enhances the effective trapping of sulfur and polysulfides. The hybrid MC-Meso C-doped TiO2/S composite material possesses rutile TiO2 nanotube structure with successful carbon doping while sulfur is uniformly distributed in the hybrid MC-Meso C-doped TiO2 composite materials after the melt-infusion process. The electrochemical measurement of the hybrid material also shows improved cycle stability and rate performance with high sulfur loading (61.04%). The material delivers an initial discharge capacity of 802 mAh g-1 and maintains it at 578 mAh g-1 with a columbic efficiency greater than 97.1% after 140 cycles at 0.1 C. This improvement is thought to be attributed to the unique hybrid nanostructure of the MC-Meso C-doped TiO2 host and the good dispersion of sulfur in the narrow pores of the MC spheres and the mesoporous C-doped TiO2 support.

  14. Improved performance of electrodes based on carbonized olive stones/S composites by impregnating with mesoporous TiO2 for advanced Lisbnd S batteries

    Science.gov (United States)

    Moreno, Noelia; Caballero, Álvaro; Morales, Julián; Rodríguez-Castellón, Enrique

    2016-05-01

    Carbons obtained from biomass have attracted a lot of attention for use as electrodes for Li-ion batteries. Less attention has been paid to their use in Lisbnd S batteries in spite of the higher energy densities. Here, we optimized the electrochemical properties of an activated carbon (OSAC) obtained from olive stones with the help of mesoporous TiO2. The OSAC@TiO2/S hybrid composite exhibited improved electrochemical performance compared with the OSAC/S composite. The presence of TiO2 increased the delivered capacity of the cell by more than 60%, and the rate capability was notably improved. The cell could operate at current densities of 3350 mA g-1 (2 C), releasing an average capacity of 500 mAh g-1 with a coulombic efficiency close to 100%. This improvement in the electrochemical performance is attributed to the sorbent properties of TiO2 towards Li polysulfides and its facility to insert Li, which enhances the electronic and ionic conductivity of the hybrid composite.

  15. A Novel Electrochemical Sensor for Probing Doxepin Created on a Glassy Carbon Electrode Modified with Poly(4-Amino- benzoic Acid/Multi-Walled Carbon Nanotubes Composite Film

    Directory of Open Access Journals (Sweden)

    Ji-Lie Kong

    2010-09-01

    Full Text Available A novel electrochemical sensor for sensitive detection of doxepin was prepared, which was based on a glassy carbon electrode modified with poly(4-aminobenzoic acid/multi-walled carbon nanotubes composite film [poly(4-ABA/MWNTs/GCE]. The sensor was characterized by scanning electron microscopy and electrochemical methods. It was observed that poly(4-ABA/MWNTs/GCE showed excellent preconcentration function and electrocatalytic activities towards doxepin. Under the selected conditions, the anodic peak current was linear to the logarithm of doxepin concentration in the range from 1.0 ´ 10−9 to 1.0 ´ 10−6 M, and the detection limit obtained was 1.0 × 10−10 M. The poly(4-ABA/MWNTs/GCE was successfully applied in the measurement of doxepin in commercial pharmaceutical formulations, and the analytical accuracy was confirmed by comparison with a conventional ultraviolet spectrophotometry assay.

  16. Electrochemical performance of polyaniline nanofibres and polyaniline/multi-walled carbon nanotube composite as an electrode material for aqueous redox supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Sivakkumar, S.R.; Kim, Wan Ju; Choi, Ji-Ae; Kim, Dong-Won [Department of Applied Chemistry, Hanbat National University, Yusung-Gu, Daejeon 305-719 (Korea); MacFarlane, Douglas R. [School of Chemistry, Monash University, Wellington Road, Clayton, Vic. 3800 (Australia); Forsyth, Maria [Department of Materials Engineering, Monash University, Wellington Road, Clayton, Vic. 3800 (Australia)

    2007-09-27

    Polyaniline (PANI) nanofibres are synthesized by interfacial polymerization and their electrochemical performance is evaluated in an aqueous redox supercapacitor constituted as a two-electrode cell. The initial specific capacitance of the cell is 554 F g{sup -1} at a constant current of 1.0 A g{sup -1}, but this value rapidly decreases on continuous cycling. In order to improve the cycleability of the supercapacitor, a composite of polyaniline with multi-walled carbon nanotubes (CNTs) is synthesized by in situ chemical polymerization. Its capacitive behaviour is evaluated in a similar cell configuration. A high initial specific capacitance of 606 F g{sup -1} is obtained with good retention on cycling. In both supercapacitors, the effect of charging potential on cycling performances is investigated. (author)

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

    International Nuclear Information System (INIS)

    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.

  18. Formation of hydrogen from the CO–H2O system using porous Gd-doped ceria electrochemical cell with MnO cathode and Fe3O4 anode

    Directory of Open Access Journals (Sweden)

    Koki Ueda

    2015-03-01

    Full Text Available This paper reports the outlet gas composition and phase change of electrodes during the CO–H2O reaction (CO + H2O → H2 + CO2 using an electrochemical cell with MnO–GDC (Gd-doped ceria: Ce0.8Gd0.2O1.9 cathode/porous GDC electrolyte/Fe3O4–GDC anode system. In the cathode, oxidation of MnO by H2O (3MnO + H2O → Mn3O4 + H2 and electrochemical reduction of Mn3O4 occurred (Mn3O4 + 2e− → 3MnO + O2−. In the anode, reduction of Fe3O4 by CO (Fe3O4 + CO → 3FeO + CO2 and electrochemical oxidation of FeO occurred (3FeO + O2− → Fe3O4 + 2e−. H2 and CO2 gases were produced through the above catalytic reactions. The fraction of H2 gas in the outlet gas increased at a high heating temperature and was 30–50% at 700 °C. As a parallel reaction of the CO–H2O reaction, the supplied CO gas was decomposed to CO2 and solid carbon over Fe3O4 in the anode at low temperatures (disproportion of CO, 2CO → CO2 + C.

  19. Electrophoretic deposition of dense Sr- and Mg-doped LaGaO{sub 3} electrolyte films on porous La-doped ceria for intermediate temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Bozza, F.; Polini, R.; Traversa, E. [Dipartimento di Scienze e Tecnologie Chimiche, Universita di Roma Tor Vergata (Italy)

    2008-10-15

    The application of the electrophoretic deposition (EPD) technique to the preparation of dense La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 2.8} (LSGM) electrolyte films for intermediate temperature solid oxide fuel cells (IT-SOFCs) was investigated. Suspensions of LSGM were prepared in acetone +I{sub 2}+H{sub 2}O dispersion media. The effects of water and iodine content, of the applied voltage, and of powder loading on the EPD rate were systematically studied using metallic substrates (Pt and stainless steel). This allowed to identify the suitable set of EPD process parameters that were used to deposit LSGM films on tape-cast composite electrodes, composed of lanthanum-doped ceria (La{sub 0.4}Ce{sub 0.6}O{sub 2-x}, LDC), polyvinylidene difluoride (PVDF) and carbon powders. After EPD, dense and crack-free 15 {mu}m thick LSGM films were obtained on porous LDC by co-firing in air at 1,490 C. Line profile analyses performed by energy dispersive X-ray spectroscopy (EDS) did not reveal any interdiffusion of ions across the LSGM/LDC interface. The chemical and structural compatibility of LSGM with LDC was also checked by heat treating a mixture of the two powders (1:1 weight ratio) using the same thermal cycle as that of the LDC/LSGM bi-layer co-firing at 1,490 C. EPD has thus proven to be a viable way for manufacturing anode-supported LSGM electrolyte films. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  20. Electrochemical studies of thin films of conducting polymers and conducting polymer composites deposited on metal and semiconductor electrodes

    Science.gov (United States)

    Nagasubramanian, G.; Di Stefano, S.; Moacanin, J.

    1987-01-01

    Electrochemical studies indicate that poly(Isothianaphthene) or PITN, can be p-doped only. Electrochemical properties of PITN and Nafion-PITN in acetonitrile solutions containing tetra-phenyl Phosphonium chloride as supporting electrolyte are compared. In both cases, the electrochemical behavior of thin films are different from that of thick films. In addition, Nafion does not seem to alter the electrochemical properties of PITN. Cyclic voltammetric and chronocoulometric measurements were made to compute the diffusion coefficient of the counter ions. Electrochemical behavior of both PITN and Nafion-PITN in acetonitrile solution containing different counter ions are described. PITN, when electrochemically deposited, apparently neither passivates surface states present nor forms ohmic contacts with p-Si or p(+)Si single-crystal electrodes.