Exploring the electrochemical performance of graphitic paste electrodes: graphene vs. graphite.

Science.gov (United States)

Figueiredo-Filho, Luiz C S; Brownson, Dale A C; Gómez-Mingot, Maria; Iniesta, Jesús; Fatibello-Filho, Orlando; Banks, Craig E

2013-11-07

We report the fabrication, characterisation (SEM, TEM, XPS and Raman spectroscopy) and electrochemical implementation of a graphene paste electrode. The paste electrodes utilised are constructed by simply mixing graphene with mineral oil (which acts as a binder) prior to loading the resultant paste into a piston-driven polymeric-tubing electrode-shell, where this electrode configuration allows for rapid renewal of the electrode surface. The fabricated paste electrode is electrochemically characterised using both inner-sphere and outer-sphere redox probes, namely potassium ferrocyanide(ii), hexaammine-ruthenium(iii) chloride and hexachloroiridate(iii), in addition to the biologically relevant and electroactive analytes, l-ascorbic acid (AA) and uric acid (UA). Comparisons are made with a graphite paste alternative and the benefits of graphene implementation as a paste electrode within electrochemistry are explored, as well as the characterisation of their electroanalytical performances. We reveal no observable differences in the electrochemical performance and thus suggest that there are no advantages of using graphene over graphite in the fabrication of paste electrodes. Such work is highly important and informative for those working in the field of electroanalysis where electrochemistry can provide portable, rapid, reliable and accurate sensing protocols (bringing the laboratory into the field), with particular relevance to those searching for new electrode materials.

Corrosion studies using potentiodynamic and EIS electrochemical techniques of welded lean duplex stainless steel UNS S82441

Science.gov (United States)

Brytan, Z.; Niagaj, J.; Reiman, Ł.

2016-12-01

The corrosion characterisation of lean duplex stainless steel (1.4662) UNS S82441 welded joints using the potentiodynamic test and electrochemical impedance spectroscopy in 1 M NaCl solution are discussed. The influence of autogenous TIG welding parameters (amount of heat input and composition of shielding gases like Ar and Ar-N2 and an Ar-He mixture), as well as A-TIG welding was studied. The influence of welding parameters on phase balance, microstructural changes and the protective properties of passive oxide films formed at the open circuit potential or during the anodic polarisation were studied. From the results of the potentiodynamic test and electrochemical impedance spectroscopy of TIG and A-TiG, welded joints show a lower corrosion resistance compared to non-welded parent metal, but introducing heat input properly during welding and applying shielding gases rich in nitrogen or helium can increase austenitic phase content, which is beneficial for corrosion resistance, and improves surface oxide layer resistance in 1 M NaCl solution.

Characterising of solid state electrochemical cells under operation

DEFF Research Database (Denmark)

Holtappels, Peter

2014-01-01

Compared to significant progress in PEMFC especially regarding the utilization of complex fuels such as methanol significant progress has been made by applying spectroscopic / differential IR and spectrometric techniques to working fuel cells, the processes in solid state high temperature...... electrochemical cells are still a "black box". In order to identify local reaction sites, surface coverage and potential/current introduced materials and surface modifications, in situ techniques are needed to gain a better understanding of the elementary and performance limiting steps for these cells...

Electrochemical Characterisation of Bio-Bottle-Voltaic (BBV) Systems Operated with Algae and Built with Recycled Materials.

Science.gov (United States)

Bateson, Peter; Fleet, Jack E H; Riseley, Anthony S; Janeva, Elena; Marcella, Anastasia S; Farinea, Chiara; Kuptsova, Maria; Conde Pueyo, Núria; Howe, Christopher J; Bombelli, Paolo; Parker, Brenda M

2018-04-17

Photobioelectrochemical systems are an emerging possibility for renewable energy. By exploiting photosynthesis, they transform the energy of light into electricity. This study evaluates a simple, scalable bioelectrochemical system built from recycled plastic bottles, equipped with an anode made from recycled aluminum, and operated with the green alga Chlorella sorokiniana . We tested whether such a system, referred to as a bio-bottle-voltaic (BBV) device, could operate outdoors for a prolonged time period of 35 days. Electrochemical characterisation was conducted by measuring the drop in potential between the anode and the cathode, and this value was used to calculate the rate of charge accumulation. The BBV systems were initially able to deliver ~500 mC·bottle −1 ·day −1 , which increased throughout the experimental run to a maximum of ~2000 mC·bottle −1 ·day −1 . The electrical output was consistently and significantly higher than that of the abiotic BBV system operated without algal cells (~100 mC·bottle −1 ·day −1 ). The analysis of the rate of algal biomass accumulation supported the hypothesis that harvesting a proportion of electrons from the algal cells does not significantly perturb the rate of algal growth. Our finding demonstrates that bioelectrochemical systems can be built using recycled components. Prototypes of these systems have been displayed in public events; they could serve as educational toolkits in schools and could also offer a solution for powering low-energy devices off-grid.

Electrochemical Characterisation of Bio-Bottle-Voltaic (BBV Systems Operated with Algae and Built with Recycled Materials

Directory of Open Access Journals (Sweden)

Peter Bateson

2018-04-01

Full Text Available Photobioelectrochemical systems are an emerging possibility for renewable energy. By exploiting photosynthesis, they transform the energy of light into electricity. This study evaluates a simple, scalable bioelectrochemical system built from recycled plastic bottles, equipped with an anode made from recycled aluminum, and operated with the green alga Chlorella sorokiniana. We tested whether such a system, referred to as a bio-bottle-voltaic (BBV device, could operate outdoors for a prolonged time period of 35 days. Electrochemical characterisation was conducted by measuring the drop in potential between the anode and the cathode, and this value was used to calculate the rate of charge accumulation. The BBV systems were initially able to deliver ~500 mC·bottle−1·day−1, which increased throughout the experimental run to a maximum of ~2000 mC·bottle−1·day−1. The electrical output was consistently and significantly higher than that of the abiotic BBV system operated without algal cells (~100 mC·bottle−1·day−1. The analysis of the rate of algal biomass accumulation supported the hypothesis that harvesting a proportion of electrons from the algal cells does not significantly perturb the rate of algal growth. Our finding demonstrates that bioelectrochemical systems can be built using recycled components. Prototypes of these systems have been displayed in public events; they could serve as educational toolkits in schools and could also offer a solution for powering low-energy devices off-grid.

Development of a pilot size of electrochemical flushing equipment for radioactive soil and concrete

International Nuclear Information System (INIS)

Kim, Gye Nam; Moon, Jei Kwon; Choi, Wang Kyu; Yang, Byeong Il; Shon, Jong Sik; Hong, Dae Seok

2010-01-01

A pilot size of electrochemical flushing equipment will be manufactured suitable to the contamination characteristics of radioactive soil and concrete stored in KAERI radioactive waste storage. An optimal reagent and an optimal decontamination conditions should be decided through many experiments. - Contamination characterises analysis of TRIGA radioactive soil and concrete - Manufacture of pilot-scale electrochemical flushing equipment - Manufacture and improvement of suitable electrochemical flushing equipment for contamination characteristics in pilot size - Decontamination experiments of electrochemical flushing equipment in a pilot scale

Functional Testing and Characterisation of ISFETs on Wafer Level by Means of a Micro-droplet Cell

Directory of Open Access Journals (Sweden)

Michael J. Schöning

2006-04-01

Full Text Available A wafer-level functionality testing and characterisation system for ISFETs (ion-sensitive field-effect transistor is realised by means of integration of a specifically designedcapillary electrochemical micro-droplet cell into a commercial wafer prober-station. Thedeveloped system allows the identification and selection of “good” ISFETs at the earlieststage and to avoid expensive bonding, encapsulation and packaging processes for non-functioning ISFETs and thus, to decrease costs, which are wasted for bad dies. Thedeveloped system is also feasible for wafer-level characterisation of ISFETs in terms ofsensitivity, hysteresis and response time. Additionally, the system might be also utilised forwafer-level testing of further electrochemical sensors.

Electrochemical characterisation of CaCl2 deficient LiCl–KCl–CaCl2 eutectic melt and electro-deoxidation of solid UO2

International Nuclear Information System (INIS)

Sri Maha Vishnu, D.; Sanil, N.; Mohandas, K.S.; Nagarajan, K.

2016-01-01

The CaCl 2 deficient ternary eutectic melt LiCl–KCl–CaCl 2 (50.5: 44.2: 5.3 mol %) was electrochemically characterised by cyclic voltammetry and polarization techniques in the context of its probable use as the electrolyte in the electrochemical reduction of solid UO 2 to uranium metal. Tungsten (cathodic polarization) and graphite (anodic polarization) working electrodes were used in these studies carried out in the temperature range 623 K–923 K. The cathodic limit of the melt was observed to be set by the deposition of Ca 2+ ions followed by Li + ions on the tungsten electrode and the anodic limit by oxidation of chloride ions on the graphite electrode (chlorine evolution). The difference between the onset potential of deposition of Ca 2+ and Li + was found to be 0.241 V at a scan rate of 20 mV/s at 623 K and the difference decreased with increase in temperature and vanished at 923 K. Polarization measurements with stainless steel (SS) cathode and graphite anode at 673 K showed the possibility of low–energy reactions occurring on the UO 2 electrode in the melt. UO 2 pellets were cathodically polarized at 3.9 V for 25 h to test the feasibility of electro-reduction to uranium in the melt. The surface of the pellets was found reduced to U metal. - Highlights: • Electrochemically characterized LiCl–KCl–CaCl 2 (50.5: 44.2: 5.3 mol %) melt by CV, LSV and polarization techniques. • Ca 2+ deposits first on tungsten working electrode followed by Li + . Cl − discharges on graphite to liberate chlorine gas. • Surface of UO 2 pellet reduced to U in the melt with low carbon contamination of melt. • Slow reduction of UO 2 due to slow kinetics and low solubility of oxide ions in the low temperature melt.

Electrochemical synthesis of hydrogen peroxide: Rotating disk electrode and fuel cell studies

International Nuclear Information System (INIS)

Lobyntseva, Elena; Kallio, Tanja; Alexeyeva, Nadezda; Tammeveski, Kaido; Kontturi, Kyoesti

2007-01-01

The electrochemical reduction of oxygen on various catalysts was studied using the thin-layer rotating disk electrode (RDE) method. High-surface-area carbon was modified with an anthraquinone derivative and gold nanoparticles. Polytetrafluoroethylene (PTFE) and cationic polyelectrolyte (FAA) were used as binders in the preparation of thin-film electrodes. Our primary goal was to find a good electrocatalyst for the two-electron reduction of oxygen to hydrogen peroxide. All electrochemical measurements were carried out in 0.1 M KOH. Cyclic voltammetry was used in order to characterise the surface processes of the modified electrodes in O 2 -free electrolyte. The RDE results revealed that the carbon-supported gold nanoparticles are active catalysts for the four-electron reduction of oxygen in alkaline solution. Anthraquinone-modified high-area carbon catalyses the two-electron reduction at low overpotentials, which is advantageous for hydrogen peroxide production. In addition, the polymer electrolyte fuel cell technology was used for the generation of hydrogen peroxide. The cell was equipped with a bipolar membrane which consisted of commercial Nafion 117 as a cation-exchange layer and FT-FAA as an anion-exchange layer. The bipolar membranes were prepared by a hot pressing method. Use of the FAA ionomer as a binder for the anthraquinone-modified carbon catalyst resulted in production of hydrogen peroxide

Characterisation and optimisation of electrochemically addressable templated polyaniline structures

OpenAIRE

Gorey, Brian

2014-01-01

The application of intrinsically conducting polymers (ICPs) for lab-on-chip applications has shown recent success with many research groups reporting novel methods to incorporate and control ICP materials in lab-on-chip platforms. Chemical and electrochemical polymerisation have been used to successfully incorporate ICP materials within microfluidic platforms. However, fabrication of 3D ordered flow-through ICP structures has remained a limitation in this research area to date. This work des...

Effect of electrochemical oxidation of a viscose rayon based ...

African Journals Online (AJOL)

A viscose rayon based activated carbon cloth (ACC) was electrochemically oxidised to enhance its cation sorption capacity for comparison with as-received ACC. ACCs were characterised by sodium capacity measurement, pH titration, zeta potential measurement, elemental analysis, Brunauer-Emmet- Teller surface area ...

Electrochemical and genomic analysis of novel electroactive isolates obtained via potentiostatic enrichment from tropical sediment

Science.gov (United States)

Doyle, Lucinda E.; Yung, Pui Yi; Mitra, Sumitra D.; Wuertz, Stefan; Williams, Rohan B. H.; Lauro, Federico M.; Marsili, Enrico

2017-07-01

Enrichment of electrochemically-active microorganisms (EAM) to date has mostly relied on microbial fuel cells fed with wastewater. This study aims to enrich novel EAM by exposing tropical sediment, not frequently reported in the literature, to sustained anodic potentials. Voltamperometric techniques and electrochemical impedance spectroscopy, performed over a wide range of potentials, characterise extracellular electron transfer (EET) over time. Applied potential is found to affect biofilm electrochemical signature. Geobacter metallireducens is heavily enriched on the electrodes, as determined by metagenomic and metatranscriptomic analysis, in the first report of the species in a lactate-fed system. Two novel isolates are grown in pure culture from the enrichment, identified by 16S rRNA gene sequencing as Aeromonas and Enterobacter, respectively. The names proposed are Aeromonas sp. CL-1 and Enterobacter sp. EA-1. Both isolates are capable of EET on carbon felt and screen-printed carbon electrodes without the addition of exogenous redox mediators. Enterobacter sp. EA-1 can also perform mediated electron transfer using the soluble redox mediator 2-hydroxy-1,4-naphthoquinone (HNQ). Both isolates are able to use acetate and lactate as electron donors. This work outlines a comprehensive methodology for characterising novel EAM from unconventional inocula.

Regeneration of phenolic antioxidants from phenoxyl radicals: An ESR and electrochemical study of antioxidant hierarchy

DEFF Research Database (Denmark)

Jørgensen, Lars V.; Madsen, Helle L.; Thomsen, Marianne K.

1999-01-01

Radicals from the flavonoids quercetin, (+)-catechin, (+/-)-taxifolin and luteolin, and from all-rac-alpha-tocopherol have been generated electrochemically by one-electron oxidation in deaerated dimethylformamide (DMF), and characterised by electron spin resonance spectroscopy (ESR) after spin......-trapping by 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). Simulations of the ESR spectrum based on estimated coupling constants of the spin-trapped quercetin radical, confirmed that this antioxidant radical is oxygen-centered. The complex mixture of radicals, quinoid intermediates and stable two-electron oxidation...

Development and characterisation of Ni-Si3N4 nanocomposites

International Nuclear Information System (INIS)

R, Mohan Reddy; M, Praveen B.; M, Praveen C.; V, Venkatesha T.; Kumar N B, Rithin

2015-01-01

Nickel–Si 3 N 4 composites were generated by means of pulse-reverse (PR) electrodeposition technique. The corrosion rate was calculated for the composites by electrochemical methods such as polarisation and impedance methods. Composites were characterised by scanning electron microscope (SEM) and X-ray diffractometer (XRD) to evaluate their microstructures. Coatings obtained by PR method shows more corrosion resistance than DC generated coatings

Screen-printed carbon electrode modified on its surface with amorphous carbon nitride thin film: Electrochemical and morphological study

Energy Technology Data Exchange (ETDEWEB)

Ghamouss, F. [Universite de Nantes, UMR 6006-CNRS, FR-2465-CNRS, Laboratoire d' Analyse isotopique et Electrochimique de Metabolismes (LAIEM) (France); Tessier, P.-Y. [Universite de Nantes, UMR CNRS 6502, Institut des Materiaux Jean Rouxel - IMN Faculte des Sciences and des Techniques de Nantes, 2 rue de la Houssiniere, 44322 Nantes Cedex 3 (France); Djouadi, A. [Universite de Nantes, UMR CNRS 6502, Institut des Materiaux Jean Rouxel - IMN Faculte des Sciences and des Techniques de Nantes, 2 rue de la Houssiniere, 44322 Nantes Cedex 3 (France); Besland, M.-P. [Universite de Nantes, UMR CNRS 6502, Institut des Materiaux Jean Rouxel - IMN Faculte des Sciences and des Techniques de Nantes, 2 rue de la Houssiniere, 44322 Nantes Cedex 3 (France); Boujtita, M. [Universite de Nantes, UMR 6006-CNRS, FR-2465-CNRS, Laboratoire d' Analyse isotopique et Electrochimique de Metabolismes (LAIEM) (France)]. E-mail: mohammed.boujtita@univ-nantes.fr

2007-04-20

The surface of a screen-printed carbon electrode (SPCE) was modified by using amorphous carbon nitride (a-CN {sub x}) thin film deposited by reactive magnetron sputtering. Scanning electron microscopy and photoelectron spectroscopy measurements were used to characterise respectively the morphology and the chemical structure of the a-CN {sub x} modified electrodes. The incorporation of nitrogen in the amorphous carbon network was demonstrated by X ray photoelectron spectroscopy. The a-CN {sub x} layers were deposited on both carbon screen-printed electrode (SPCE) and silicon (Si) substrates. A comparative study showed that the nature of substrate, i.e. SPCE and Si, has a significant effect on both the surface morphology of deposited a-CN {sub x} film and their electrochemical properties. The improvement of the electrochemical reactivity of SPCE after a-CN {sub x} film deposition was highlighted both by comparing the shapes of voltammograms and calculating the apparent heterogeneous electron transfer rate constant.

Study of the electrodeposition of rhenium thin films by electrochemical quartz microbalance and X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Schrebler, R.; Cury, P.; Suarez, C.; Munoz, E.; Vera, F.; Cordova, R.; Gomez, H.; Ramos-Barrado, J.R.; Leinen, D.; Dalchiele, E.A.

2005-01-01

Rhenium thin films were prepared by electrodeposition from an aqueous solution containing 0.1 M Na 2 SO 4 +H 2 SO 4 , pH 2 in presence of y mM HReO 4 . As substrates polycrystalline gold (y=0.75 mM HReO 4 ) and monocrystalline n-Si(100) (y=40 mM HReO 4 ) were used. The electrochemical growth of rhenium was studied by cyclic voltammetry and electrochemical quartz microbalance on gold electrodes. The results found in the potential region before the hydrogen evolution reaction (her) showed that ReO 3 , ReO 2 and Re 2 O 3 with different hydration grades can be formed. In the potential region where the her is occurring, either on gold or n-Si(100) the electrodeposition of metallic rhenium takes place. On both substrates, rhenium films were formed by electrolysis at constant potential and X-ray photoelectron spectroscopy technique was used to characterise these deposits. It was concluded that the electrodeposited films were of metallic rhenium and only the uppermost atomic layer contained rhenium oxide species

Effect of antimony, bismuth and calcium addition on corrosion and electrochemical behaviour of AZ91 magnesium alloy

International Nuclear Information System (INIS)

Zhou Wei; Aung, Naing Naing; Sun Yangshan

2009-01-01

This study investigated the effect of antimony, bismuth and calcium addition on the corrosion and electrochemical behaviour of AZ91 magnesium alloy in 3.5% NaCl solution. Techniques including constant immersion, electrochemical potentiodynamic polarisation, scanning electron microscopy (SEM), energy dispersed spectroscopy (EDS) and X-ray diffraction (XRD) were used to characterise electrochemical and corrosion properties and surface topography. It was found that corrosion attack occurred preferentially on Mg 3 Bi 2 and Mg 3 Sb 2 particles while Mg 17 Al 8 Ca 0.5 and Mg 2 Ca phases showed no detrimental effect on corrosion. Combined addition of small amounts of bismuth and antimony to the AZ91 alloy resulted in significant increase in corrosion rate

Three dimensional electrochemical system for neurobiological studies

DEFF Research Database (Denmark)

Vazquez, Patricia; Dimaki, Maria; Svendsen, Winnie Edith

2009-01-01

In this work we report a novel three dimensional electrode array for electrochemical measurements in neuronal studies. The main advantage of working with these out-of-plane structures is the enhanced sensitivity of the system in terms of measuring electrochemical changes in the environment...

Electrochemical characterisation of CaCl{sub 2} deficient LiCl–KCl–CaCl{sub 2} eutectic melt and electro-deoxidation of solid UO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Sri Maha Vishnu, D., E-mail: smvd2@cam.ac.uk; Sanil, N.; Mohandas, K.S.; Nagarajan, K.

2016-03-15

The CaCl{sub 2} deficient ternary eutectic melt LiCl–KCl–CaCl{sub 2} (50.5: 44.2: 5.3 mol %) was electrochemically characterised by cyclic voltammetry and polarization techniques in the context of its probable use as the electrolyte in the electrochemical reduction of solid UO{sub 2} to uranium metal. Tungsten (cathodic polarization) and graphite (anodic polarization) working electrodes were used in these studies carried out in the temperature range 623 K–923 K. The cathodic limit of the melt was observed to be set by the deposition of Ca{sup 2+} ions followed by Li{sup +} ions on the tungsten electrode and the anodic limit by oxidation of chloride ions on the graphite electrode (chlorine evolution). The difference between the onset potential of deposition of Ca{sup 2+} and Li{sup +} was found to be 0.241 V at a scan rate of 20 mV/s at 623 K and the difference decreased with increase in temperature and vanished at 923 K. Polarization measurements with stainless steel (SS) cathode and graphite anode at 673 K showed the possibility of low–energy reactions occurring on the UO{sub 2} electrode in the melt. UO{sub 2} pellets were cathodically polarized at 3.9 V for 25 h to test the feasibility of electro-reduction to uranium in the melt. The surface of the pellets was found reduced to U metal. - Highlights: • Electrochemically characterized LiCl–KCl–CaCl{sub 2} (50.5: 44.2: 5.3 mol %) melt by CV, LSV and polarization techniques. • Ca{sup 2+} deposits first on tungsten working electrode followed by Li{sup +}. Cl{sup −} discharges on graphite to liberate chlorine gas. • Surface of UO{sub 2} pellet reduced to U in the melt with low carbon contamination of melt. • Slow reduction of UO{sub 2} due to slow kinetics and low solubility of oxide ions in the low temperature melt.

The influence of current collector corrosion on the performance of electrochemical capacitors

Science.gov (United States)

Wojciechowski, Jarosław; Kolanowski, Łukasz; Bund, Andreas; Lota, Grzegorz

2017-11-01

This paper discusses the effect of current collector (stainless steel 316L) corrosion on the performance of electrochemical capacitors operated in aqueous electrolytes. This topic seems to be often neglected in scientific research. The studied electrolytes were 1 M H2SO4, 1 M KI, 1 M Na2SO4, 1 M KOH and 6 M KOH. The corrosion process was investigated by means of selected direct and alternating current techniques. The surface of the current collectors as well as the corrosion products were characterised using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy and atomic force microscopy. Stainless steel 316L in alkaline solutions is characterised by the lowest values of corrosion potentials whereas the potentials in acidic media become the most noble. Our studies show that corrosion potentials increase with decreasing pH value. This phenomenon can be explained with the formation of passive oxide films on the stainless steel current collectors. The passive oxide films are usually thicker and more porous in alkaline solutions than that in the other electrolytes. The processes occurring at the electrode/electrolyte interfaces strongly influence the working parameters of electrochemical capacitors such as voltage, working potentials of single electrodes, self-discharge as well as the internal resistance and cycling stability.

Electrochemical study of stress corrosion cracking of copper alloys

International Nuclear Information System (INIS)

Malki, Brahim

1999-01-01

This work deals with the electrochemical study of stress corrosion of copper alloys in aqueous environment. Selective dissolution and electrochemical oxidation are two key-points of the stress corrosion of these alloys. The first part of this thesis treats of these aspects applied to Cu-Au alloys. Measurements have been performed using classical electrochemical techniques (in potentio-dynamic, potentio-static and galvano-static modes). The conditions of occurrence of an electrochemical noise is analysed using signal processing techniques. The impact on the behavior of Cu 3 Au are discussed. In the second part, the stress corrosion problem is addressed in the case of surface oxide film formation, in particular for Cu-Zn alloys. We have found useful to extend this study to mechanical stress oxidation mechanisms in the presence of an oscillating potential electrochemical system. The aim is to examine the influence of these new electrochemical conditions (galvano-static mode) on the behavior of stressed brass. Finally, the potential distribution at crack tip is calculated in order to compare the different observations [fr

Development and characterisation of Ni-Si{sub 3}N{sub 4} nanocomposites

Energy Technology Data Exchange (ETDEWEB)

R, Mohan Reddy; M, Praveen B., E-mail: bm.praveen@yahoo.co.in [Dept of Chemistry, Srinivas School of Engineering, Mukka, Mangalore - 574146, Karnataka (India); M, Praveen C. [Dept. of Chemistry, PESITM, Shimoga – 577204 (India); V, Venkatesha T. [Dept. of Studies in Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta - 577451, Karnataka (India); Kumar N B, Rithin [Dept of Physics, Srinivas School of Engineering, Mukka, Mangalore-574 146, Karnataka (India)

2015-06-24

Nickel–Si{sub 3}N{sub 4} composites were generated by means of pulse-reverse (PR) electrodeposition technique. The corrosion rate was calculated for the composites by electrochemical methods such as polarisation and impedance methods. Composites were characterised by scanning electron microscope (SEM) and X-ray diffractometer (XRD) to evaluate their microstructures. Coatings obtained by PR method shows more corrosion resistance than DC generated coatings.

ELECTROCHEMICAL STUDIES OF N'-FERROCENYLMETHYL-N ...

African Journals Online (AJOL)

2011-12-31

Phenylbenzohydrazide. FcX was studied in acetonitrile with tetrabutylammonium hexafluorophosphate as the supporting electrolyte and aqueous ethanol using the electrochemical technique. This study using cyclic (CV) and rotating ...

Electrochemical and spectroscopic study on thiolation of polyaniline

International Nuclear Information System (INIS)

Blomquist, Maija; Bobacka, Johan; Ivaska, Ari; Levon, Kalle

2013-01-01

Highlights: ► We have thiolated and characterized polyaniline films in order to verify that the thiolation process has taken place. ► Such extensive characterization of thiolation of polyaniline has not previously been reported. ► Thiolation alters the electrochemical properties of polyaniline and the process should be understood. ► Through thiolation many reactive groups may covalently be bound to the polymer backbone. ► Possibility of covalent binding makes polyaniline films an attractive substrate for, e.g., biosensors. -- Abstract: Polyaniline (PANI) is a conducting polymer, easily synthesized and lucrative for many electrochemical applications like ion-selective sensors and biosensors. Thiolated molecules, including biological ones, can be bound by nucleophilic attachment to the polyaniline backbone. These covalently bound thiols add functionality to PANI, but also cause changes in the electrochemical properties of PANI. Polyaniline studied in this work was electropolymerized on glassy carbon electrodes. 2-Mercaptoethanol (MCE) and 6-(ferrocenyl)hexanethiol (FCHT) were used as the thiols to form functionalized films. The films were characterized by cyclic voltammetry (CV), ex situ FTIR and Raman spectroscopies, electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The goal of this work was to confirm the thiolation by spectroscopic methods and to study the impact of thiolation on the electrochemical properties of PANI. Our study showed that thiolated PANI has different electrochemical properties than PANI. Although the thiolation partially reduced the PANI backbone it still remained conductive after the thiolation. Detailed understanding of the thiolation process can be very useful for future applications of PANI

Electrocatalytic activity mapping of model fuel cell catalyst films using scanning electrochemical microscopy

International Nuclear Information System (INIS)

Nicholson, P.G.; Zhou, S.; Hinds, G.; Wain, A.J.; Turnbull, A.

2009-01-01

Scanning electrochemical microscopy has been employed to spatially map the electrocatalytic activity of model proton exchange membrane fuel cell (PEMFC) catalyst films towards the hydrogen oxidation reaction (the PEMFC anode reaction). The catalyst films were composed of platinum-loaded carbon nanoparticles, similar to those typically used in PEMFCs. The electrochemical characterisation was correlated with a detailed physical characterisation using dynamic light scattering, transmission electron microscopy and field-emission scanning electron microscopy. The nanoparticles were found to be reasonably mono-dispersed, with a tendency to agglomerate into porous bead-type structures when spun-cast. The number of carbon nanoparticles with little or no platinum was surprisingly higher than would be expected based on the platinum-carbon mass ratio. Furthermore, the platinum-rich carbon particles tended to agglomerate and the clusters formed were non-uniformly distributed. This morphology was reflected in a high degree of heterogeneity in the film activity towards the hydrogen oxidation reaction.

Development of techniques for electrochemical studies in power plant environments

International Nuclear Information System (INIS)

Maekelae, K.

2000-01-01

The properties of the oxide films on the engineering alloys used as construction materials in power plants change as a result of exposure to aqueous environments. The susceptibility of the materials to different forms of corrosion is influenced by the properties of these oxide films. The structure and electrochemical properties of the oxide films are in turn dependent on the applied water chemistry. Therefore, water chemistry control has been used in minimising the impact of different corrosion phenomena in operating power plants. Since there is not only one ideal operational specification for all light water reactors, individually designed water chemistry programs are needed to take into account plant-specific design features and particular problem areas. The applicability of alternative water chemistry practices require fast and reliable in-line electrochemical techniques to monitor possible changes in the oxidation behaviour of nuclear power plant materials. This thesis summarises the work done at the Technical Research Centre of Finland over the past 10 years to increase the knowledge of factors affecting the oxidation behaviour of construction materials in aqueous coolants at high temperatures. The work started with the development of electrodes for measurement of high temperature water chemistry parameters such as pH and the corrosion potential of construction materials. After laboratory testing these electrodes were used both in test reactors and in operating nuclear power plants. These measurements showed that high temperature water chemistry monitoring may be more accurate than corresponding room temperature measurements, particularly during transient situations. However, it was also found that understanding the processes taking place within and on oxide films requires a combination of electrochemical techniques enabling characterisation of the electronic properties of these films. This conclusion resulted in development of a controlled

In-situ electrochemical study of Zr1nb alloy corrosion in high temperature Li{sup +} containing water

Energy Technology Data Exchange (ETDEWEB)

Krausová, Aneta [University of Chemistry and Technology, Technická 3, 166 28 Prague 6 (Czech Republic); Macák, Jan, E-mail: macakj@vscht.cz [University of Chemistry and Technology, Technická 3, 166 28 Prague 6 (Czech Republic); Sajdl, Petr [University of Chemistry and Technology, Technická 3, 166 28 Prague 6 (Czech Republic); Novotný, Radek [JRC-IET, Westerduinveg 3, 1755 LE Petten (Netherlands); Renčiuková, Veronika [University of Chemistry and Technology, Technická 3, 166 28 Prague 6 (Czech Republic); Vrtílková, Věra [ÚJP a.s., Nad Kamínkou 1345, 156 10 Prague 5 (Czech Republic)

2015-12-15

Long-term in-situ corrosion tests were performed in order to evaluate the influence of lithium ions on the corrosion of zirconium alloy. Experiments were carried out in a high-pressure high-temperature loop (280 °C, 8 MPa) in a high concentration water solution of LiOH (70 and 200 ppm Li{sup +}) and in a simulated WWER primary coolant environment. The kinetic parameters characterising the oxidation process have been explored using in-situ electrochemical impedance spectroscopy and slow potentiodynamic polarization. Also, a suitable equivalent circuit was suggested, which would approximate the impedance characteristics of the corrosion of Zr–1Nb alloy. The Mott–Schottky approach was used to determine the semiconducting character of the passive film. - Highlights: • Zr1Nb alloy was tested in WWER coolant and in LiOH solutions at 280 °C. • Corrosion rates were estimated in-situ from electrochemical data. • Electrochemical data agreed well with weight gains and metallography data. • Increase of corrosion rate in LiOH appeared after short exposure (300–500 h). • Very high donor densities (1.1–1.2 × 10{sup 20} cm{sup −3}) of Zr oxide grown in LiOH were found.

Impedance Spectroscopic Characterisation of Porosity in 3D Cell Culture Scaffolds with Different Channel Networks

DEFF Research Database (Denmark)

Canali, Chiara; Mohanty, Soumyaranjan; Heiskanen, Arto

2015-01-01

We present the application of electrochemical impedance spectroscopy (EIS) as a method for discriminating between different polydimethylsiloxane (PDMS) scaffolds for three-dimensional (3D) cell cultures. The validity of EIS characterisation for scaffolds having different degree of porosity...... serve as means of single-frequency measurements for fast scaffold characterization combined with in vitro monitoring of 3D cell cultures....

Electrodeposition and electrochemical characterisation of thick and thin coatings of Sb and Sb/Sb2O3 particles for Li-ion battery anodes

International Nuclear Information System (INIS)

Bryngelsson, Hanna; Eskhult, Jonas; Edstroem, Kristina; Nyholm, Leif

2007-01-01

The possibilities to electrodeposit thick coatings composed of nanoparticles of Sb and Sb 2 O 3 for use as high-capacity anode materials in Li-ion batteries have been investigated. It is demonstrated that the stability of the coatings depends on their Sb 2 O 3 concentrations as well as microstructure. The electrodeposition reactions in electrolytes with different pH and buffer capacities were studied using chronopotentiometry and electrochemical quartz crystal microbalance measurements. The obtained deposits, which were characterised with XRD and SEM, were also tested as anode materials in Li-ion batteries. The influence of the pH and buffer capacity of the deposition solution on the composition and particle size of the deposits were studied and it is concluded that depositions from a poorly buffered solution of antimony-tartrate give rise to good anode materials due to the inclusion of precipitated Sb 2 O 3 nanoparticles in the Sb coatings. Depositions under conditions yielding pure Sb coatings give rise to deposits composed of large crystalline particles with poor anode stabilities. The presence of a plateau at about 0.8 V versus Li + /Li due to SEI forming reactions and the origin of another plateau at about 0.4 V versus Li + /Li seen during the lithiation of thin Sb coatings are also discussed. It is demonstrated that the 0.4 V plateau is present for Sb coatings for which the (0 1 2) peak is the main peak in the XRD diffractogram

4D nano-tomography of electrochemical energy devices using lab-based X-ray imaging

Energy Technology Data Exchange (ETDEWEB)

Heenan, T. M. M.; Finegan, D. P.; Tjaden, B.; Lu, X.; Iacoviello, F.; Millichamp, J.; Brett, D. J. L.; Shearing, P. R.

2018-05-01

Electrochemical energy devices offer a variety of alternate means for low-carbon, multi-scale energy conversion and storage. Reactions in these devices are supported by electrodes with characteristically complex microstructures. To meet the increasing capacity and lifetime demands across a range of applications, it is essential to understand microstructural evolutions at a cell and electrode level which are thought to be critical aspects influencing material and device lifetime and performance. X-ray computed tomography (CT) has become a highly employed method for non-destructive characterisation of such microstructures with high spatial resolution. However, sub-micron resolutions present significant challenges for sample preparation and handling particularly in 4D studies, (three spatial dimensions plus time). Here, microstructural information is collected from the same region of interest within two electrode materials: a solid oxide fuel cell and the positive electrode from a lithium-ion battery. Using a lab-based X-ray instrument, tomograms with sub-micron resolutions were obtained between thermal cycling. The intricate microstructural evolutions captured within these two materials provide model examples of 4D X-ray nano-CT capabilities in tracking challenging degradation mechanisms. This technique is valuable in the advancement of electrochemical research as well as broader applications for materials characterisation.

Imparting improvements in electrochemical sensors: evaluation of different carbon blacks that give rise to significant improvement in the performance of electroanalytical sensing platforms

International Nuclear Information System (INIS)

Vicentini, Fernando Campanhã; Ravanini, Amanda E.; Figueiredo-Filho, Luiz C.S.; Iniesta, Jesús; Banks, Craig E.; Fatibello-Filho, Orlando

2015-01-01

Three different carbon black materials have been evaluated as a potential modifier, however, only one demonstrated an improvement in the electrochemical properties. The carbon black structures were characterised with SEM, XPS and Raman spectroscopy and found to be very similar to that of amorphous graphitic materials. The modifications utilised were constructed by three different strategies (using ultrapure water, chitosan and dihexadecylphosphate). The fabricated sensors are electrochemically characterised using N,N,N',N'-tetramethyl-para-phenylenediamine and both inner-sphere and outer-sphere redox probes, namely potassium ferrocyanide(II) and hexaammineruthenium(III) chloride, in addition to the biologically relevant and electroactive analytes, dopamine (DA) and acetaminophen (AP). Comparisons are made with an edge-plane pyrolytic graphite and glassy-carbon electrode and the benefits of carbon black implemented as a modifier for sensors within electrochemistry are explored, as well as the characterisation of their electroanalytical performances. We reveal significant improvements in the electrochemical performance (excellent sensitivity, faster heterogeneous electron transfer rate (HET)) over that of a bare glassy-carbon and edge-plane pyrolytic graphite electrode and thus suggest that there are substantial advantages of using carbon black as modifier in the fabrication of electrochemical based sensors. Such work is highly important and informative for those working in the field of electroanalysis where electrochemistry can provide portable, rapid, reliable and accurate sensing protocols (bringing the laboratory into the field), with particular relevance to those searching for new electrode materials

Electrochemical Reduction of solid UO2 in Molten Fluoride Salts

International Nuclear Information System (INIS)

Gibilaro, Mathieu; Cassayre, Laurent; Massot, Laurent; Chamelot, Pierre; Malmbeck, Rikard; Dugne, Olivier; Allegri, Patrick

2010-01-01

The direct electrochemical reduction of UO 2 solid pellets was carried out in LiF-CaF 2 (+ 2wt % Li 2 O) at 850 deg. C. An inert gold anode was used instead of the usual reactive sacrificial carbon anode. In this case, reduction of oxide ions yields O 2 gas evolution on the anode. Electrochemical characterisations of UO 2 pellets have been performed by linear sweep voltammetry at 10 mV/s and reduction waves associated to its direct reduction have been observed at a potential 150 mV more positive in comparison with the solvent reduction. Then, galvano-static electrolyses runs have been realised and products were characterised by SEM-EDX, EPMA/WDS and XRD. In one of the runs, uranium oxide was partially reduced and three phases were observed: non reduced UO 2 in the centre, pure metallic uranium on the external layer and an intermediate phase representing the initial stage of reduction taking place at the grain boundaries. In another run, the UO 2 sample was fully reduced. Due to oxygen removal, the U matrix had a typical coral-like structure which is characteristic of the pattern observed after the electroreduction of solid oxides. (authors)

Electrochemical Impedance Studies of SOFC Cathodes

DEFF Research Database (Denmark)

Hjelm, Johan; Søgaard, Martin; Wandel, Marie

2007-01-01

Mixed ion- and electron-conducting composite electrodes consisting of doped ceria and perovskite have been studied by electrochemical impedance spectroscopy (EIS) at different temperatures and oxygen partial pressures. This paper aims to describe the different contributions to the polarisation...

Pencil It in: Exploring the Feasibility of Hand-Drawn Pencil Electrochemical Sensors and Their Direct Comparison to Screen-Printed Electrodes

Directory of Open Access Journals (Sweden)

Elena Bernalte

2016-08-01

Full Text Available We explore the fabrication, physicochemical characterisation (SEM, Raman, EDX and XPS and electrochemical application of hand-drawn pencil electrodes (PDEs upon an ultra-flexible polyester substrate; investigating the number of draws (used for their fabrication, the pencil grade utilised (HB to 9B and the electrochemical properties of an array of batches (i.e, pencil boxes. Electrochemical characterisation of the PDEs, using different batches of HB grade pencils, is undertaken using several inner- and outer-sphere redox probes and is critically compared to screen-printed electrodes (SPEs. Proof-of-concept is demonstrated for the electrochemical sensing of dopamine and acetaminophen using PDEs, which are found to exhibit competitive limits of detection (3σ upon comparison to SPEs. Nonetheless, it is important to note that a clear lack of reproducibility was demonstrated when utilising these PDEs fabricated using the HB pencils from different batches. We also explore the suitability and feasibility of a pencil-drawn reference electrode compared to screen-printed alternatives, to see if one can draw the entire sensing platform. This article reports a critical assessment of these PDEs against that of its screen-printed competitors, questioning the overall feasibility of PDEs’ implementation as a sensing platform.

Direct electrochemical reduction of solid uranium oxide in molten fluoride salts

Science.gov (United States)

Gibilaro, Mathieu; Cassayre, Laurent; Lemoine, Olivier; Massot, Laurent; Dugne, Olivier; Malmbeck, Rikard; Chamelot, Pierre

2011-07-01

The direct electrochemical reduction of UO 2 solid pellets was carried out in LiF-CaF 2 (+2 mass.% Li 2O) at 850 °C. An inert gold anode was used instead of the usual reactive sacrificial carbon anode. In this case, oxidation of oxide ions present in the melt yields O 2 gas evolution on the anode. Electrochemical characterisations of UO 2 pellets were performed by linear sweep voltammetry at 10 mV/s and reduction waves associated to oxide direct reduction were observed at a potential 150 mV more positive in comparison to the solvent reduction. Subsequent, galvanostatic electrolyses runs were carried out and products were characterised by SEM-EDX, EPMA/WDS, XRD and microhardness measurements. In one of the runs, uranium oxide was partially reduced and three phases were observed: nonreduced UO 2 in the centre, pure metallic uranium on the external layer and an intermediate phase representing the initial stage of reduction taking place at the grain boundaries. In another run, the UO 2 sample was fully reduced. Due to oxygen removal, the U matrix had a typical coral-like structure which is characteristic of the pattern observed after the electroreduction of solid oxides.

A kinetic study of the electrochemical hydrogenation of ethylene

International Nuclear Information System (INIS)

Sedighi, S.; Gardner, C.L.

2010-01-01

In this study, we have examined the kinetics of the electrochemical hydrogenation of ethylene in a PEM reactor. While in itself this reaction is of little industrial interest, this reaction can be looked upon as a model reaction for many of the important hydrogenation processes including the refining of heavy oils and the hydrogenation of vegetable oils. To study the electrochemical hydrogenation of ethylene, several experimental techniques have been used including polarization measurements, measurement of the composition of the exit gases and potential step, transient measurements. The results show that the hydrogenation reaction proceeds rapidly and essentially to completion. By fitting the experimental transient data to the results from a zero-dimensional mathematical model of the process, a set of kinetic parameters for the reactions has been obtained that give generally good agreement with the experimental results. It seems probable that similar experimental techniques could be used to study the electrochemical hydrogenation of other unsaturated organic molecules of more industrial significance.

On the Ageing of High Energy Lithium-Ion Batteries—Comprehensive Electrochemical Diffusivity Studies of Harvested Nickel Manganese Cobalt Electrodes

Directory of Open Access Journals (Sweden)

Odile Capron

2018-01-01

Full Text Available This paper examines the impact of the characterisation technique considered for the determination of the L i + solid state diffusion coefficient in uncycled as in cycled Nickel Manganese Cobalt oxide (NMC electrodes. As major characterisation techniques, Cyclic Voltammetry (CV, Galvanostatic Intermittent Titration Technique (GITT and Electrochemical Impedance Spectroscopy (EIS were systematically investigated. L i + diffusion coefficients during the lithiation process of the uncycled and cycled electrodes determined by CV at 3.71 V are shown to be equal to 3 . 48 × 10 - 10 cm 2 ·s - 1 and 1 . 56 × 10 - 10 cm 2 ·s - 1 , respectively. The dependency of the L i + diffusion with the lithium content in the electrodes is further studied in this paper with GITT and EIS. Diffusion coefficients calculated by GITT and EIS characterisations are shown to be in the range between 1 . 76 × 10 - 15 cm 2 ·s - 1 and 4 . 06 × 10 - 12 cm 2 ·s - 1 , while demonstrating the same decreasing trend with the lithiation process of the electrodes. For both electrode types, diffusion coefficients calculated by CV show greater values compared to those determined by GITT and EIS. With ageing, CV and EIS techniques lead to diffusion coefficients in the electrodes at 3.71 V that are decreasing, in contrast to GITT for which results indicate increasing diffusion coefficient. After long-term cycling, ratios of the diffusion coefficients determined by GITT compared to CV become more significant with an increase about 1 order of magnitude, while no significant variation is seen between the diffusion coefficients calculated from EIS in comparison to CV.

Magnetic, catalytic, EPR and electrochemical studies on binuclear ...

Indian Academy of Sciences (India)

Magnetic, catalytic, EPR and electrochemical studies on binuclear copper(II) complexes ... to the oxidation of 3,5-di--butylcatechol to the corresponding quinone. ... EPR spectral studies in methanol solvent show welldefined four hyperfine ...

Project ''Electrochemical Energy Storage Systems'' 1. Jan. 1980 - 31. Dec. 1980. Report for the Ministry of Energy, February 1981

Energy Technology Data Exchange (ETDEWEB)

1981-02-15

The project ''Electrochemical Energy Storage Systems'' involves several scientific centers in Denmark (the Technical University, Odense University and Risoe National Laboratory) and Danish-English cooperation in ''Materials Research for Advanced Batteries''. The project is divided into four subprojects: (1) fabrication and properties of solid electrolytes; (2) new fast ion conductors; (3) characterisation and performance of solid solution electrodes; and (4) battery applications studies and battery assessment. The electrochemical research comprehends new materials with improved ionic conductivity - lithium nitrides and iodides, zeolites, some sodium ion conductors. Crystalline electrolytes (of TiS/sub 2//Li/sub 3/N type) are investigated. Efficient batteries for propulsion purposes have been evaluated from the economic and energy conservation point of view. Some informative activities in the field of energy conservation are reported.

Materials characterisation

International Nuclear Information System (INIS)

Azali Muhammad

2005-01-01

Various nuclear techniques have been developed and employed by technologies and scientists worldwide to physically and chemically characterise the material particularly those that have applications in industry. These include small angle neutron scattering (SANS), x-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) for the internal structural study of material, whereas, the x-ray fluorescence (XRF) for the chemical analysis, while the Moessbauer spectroscopy for the study on the magnetic properties and structural identity of material. Basic principle and instrumentations of the techniques are discussed in this chapter. Example of their applications in various disciplines particularly in characterisation of industrial materials also described

Potential of Sr isotopic analysis in ceramic provenance studies: Characterisation of Chinese stonewares

Science.gov (United States)

Li, Bao-Ping; Zhao, Jian-Xin; Greig, Alan; Collerson, Kenneth D.; Zhuo, Zhen-Xi; Feng, Yue-Xin

2005-11-01

We compare the trace element and Sr isotopic compositions of stoneware bodies made in Yaozhou and Jizhou to characterise these Chinese archaeological ceramics and examine the potential of Sr isotopes in provenance studies. Element concentrations determined by ICP-MS achieve distinct characterisation for Jizhou samples due to their restricted variation, yet had limited success with Yaozhou wares because of their large variability. In contrast, 87Sr/86Sr ratios in Yaozhou samples have a very small variation and are all significantly lower than those of Jizhou samples, which show a large variation and cannot be well characterised with Sr isotopes. Geochemical interpretation reveals that 87Sr/86Sr ratios will have greater potential to characterise ceramics made of low Rb/Sr materials such as kaolin clay, yet will show larger variations in ceramics made of high Rb/Sr materials such as porcelain stone.

Potential of Sr isotopic analysis in ceramic provenance studies: Characterisation of Chinese stonewares

International Nuclear Information System (INIS)

Li Baoping; Zhao Jianxin; Greig, Alan; Collerson, Kenneth D.; Zhuo Zhenxi; Feng Yuexin

2005-01-01

We compare the trace element and Sr isotopic compositions of stoneware bodies made in Yaozhou and Jizhou to characterise these Chinese archaeological ceramics and examine the potential of Sr isotopes in provenance studies. Element concentrations determined by ICP-MS achieve distinct characterisation for Jizhou samples due to their restricted variation, yet had limited success with Yaozhou wares because of their large variability. In contrast, 87 Sr/ 86 Sr ratios in Yaozhou samples have a very small variation and are all significantly lower than those of Jizhou samples, which show a large variation and cannot be well characterised with Sr isotopes. Geochemical interpretation reveals that 87 Sr/ 86 Sr ratios will have greater potential to characterise ceramics made of low Rb/Sr materials such as kaolin clay, yet will show larger variations in ceramics made of high Rb/Sr materials such as porcelain stone

Raman Spectroscopy and Electrochemical Investigations of Pt Electrocatalyst Supported on Carbon Prepared through Plasma Pyrolysis of Natural Gas

Directory of Open Access Journals (Sweden)

Tereza Cristina Santos Evangelista

2015-01-01

Full Text Available Physicochemical and electrochemical characterisations of Pt-based electrocatalysts supported on carbon (Vulcan carbon, C1, and carbon produced by plasma pyrolysis of natural gas, C2 toward ethanol electrooxidation were investigated. The Pt20/C180 and Pt20/C280 electrocatalysts were prepared by thermal decomposition of polymeric precursors at 350°C. The electrochemical and physicochemical characterisations of the electrocatalysts were performed by means of X-ray diffraction (XRD, transmission electron microscope (TEM, Raman scattering, cyclic voltammetry, and chronoamperometry tests. The XRD results show that the Pt-based electrocatalysts present platinum metallic which is face-centered cubic structure. The results indicate that the Pt20/C180 electrocatalyst has a smaller particle size (10.1–6.9 nm compared with the Pt20/C280 electrocatalyst; however, the Pt20/C280 particle sizes are similar (12.8–10.4 nm and almost independent of the reflection planes, which suggests that the Pt crystallites grow with a radial shape. Raman results reveal that both Vulcan carbon and plasma carbon are graphite-like materials consisting mostly of sp2 carbon. Cyclic voltammetry and chronoamperometry data obtained in this study indicate that the deposition of Pt on plasma carbon increases its electrocatalytic activity toward ethanol oxidation reaction.

Potential of Sr isotopic analysis in ceramic provenance studies: Characterisation of Chinese stonewares

Energy Technology Data Exchange (ETDEWEB)

Li Baoping [Advanced Centre for Queensland University Isotope Research Excellence (ACQUIRE), University of Queensland, Brisbane, Qld 4072 (Australia)]. E-mail: b.li@uq.edu.au; Zhao Jianxin [Advanced Centre for Queensland University Isotope Research Excellence (ACQUIRE), University of Queensland, Brisbane, Qld 4072 (Australia); Greig, Alan [Advanced Centre for Queensland University Isotope Research Excellence (ACQUIRE), University of Queensland, Brisbane, Qld 4072 (Australia); Collerson, Kenneth D. [Advanced Centre for Queensland University Isotope Research Excellence (ACQUIRE), University of Queensland, Brisbane, Qld 4072 (Australia); Zhuo Zhenxi [Shaanxi Provincial Institute of Archaeology, Xi' an 710054 (China); Feng Yuexin [Advanced Centre for Queensland University Isotope Research Excellence (ACQUIRE), University of Queensland, Brisbane, Qld 4072 (Australia)

2005-11-15

We compare the trace element and Sr isotopic compositions of stoneware bodies made in Yaozhou and Jizhou to characterise these Chinese archaeological ceramics and examine the potential of Sr isotopes in provenance studies. Element concentrations determined by ICP-MS achieve distinct characterisation for Jizhou samples due to their restricted variation, yet had limited success with Yaozhou wares because of their large variability. In contrast, {sup 87}Sr/{sup 86}Sr ratios in Yaozhou samples have a very small variation and are all significantly lower than those of Jizhou samples, which show a large variation and cannot be well characterised with Sr isotopes. Geochemical interpretation reveals that {sup 87}Sr/{sup 86}Sr ratios will have greater potential to characterise ceramics made of low Rb/Sr materials such as kaolin clay, yet will show larger variations in ceramics made of high Rb/Sr materials such as porcelain stone.

Electrochemical deposition of Cu and Nb from pyrrolidinium based ionic liquid

Energy Technology Data Exchange (ETDEWEB)

Mascia, Michele, E-mail: michele.mascia@unica.it [Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali Università degli Studi di Cagliari, via Marengo 2, 09123 Cagliari (Italy); Vacca, Annalisa; Mais, Laura; Palmas, Simonetta [Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali Università degli Studi di Cagliari, via Marengo 2, 09123 Cagliari (Italy); Musu, Elodia [Laboratorio Telemicroscopia Industriale, Sardegna Ricerche, Polaris, Parco Tecnologico della Sardegna, Edificio 3, Loc. Piscinamanna, 09010 Pula, CA (Italy); Delogu, Francesco [Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali Università degli Studi di Cagliari, via Marengo 2, 09123 Cagliari (Italy)

2014-11-28

A study on the electrochemical deposition of Cu/Nb composites is presented in this work. The electrodeposition tests were performed using 1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulphonyl) imide as solvent. The electrochemical behaviour of copper and niobium ions was investigated by cyclic and linear sweep voltammetries, allowing to obtain information on potentials and mechanisms of deposition. Firstly, the electrodeposition of Nb on Cu substrate and of Cu on Nb substrate was investigated; then, the deposition of Cu and Nb in dual bath mode was considered. All the experimental tests were carried out at 125 °C under inert atmosphere, in order to avoid interference of water and oxygen. According to the electrochemistry of the metals considered and based on the experimental results, the possible reaction path for the oxidation/reduction was proposed. Deposition tests were carried out at different potentials and the related samples were analysed by scanning electron microscopy and energy dispersive X-ray spectroscopy. Structural and chemical analyses indicate that the obtained deposits cover uniformly the electrode surface and exhibit individual layers with a characteristic size ranging between 50 and 100 nm. - Highlights: • Cu/Nb composites were obtained by electro-deposition from ionic liquid. • The electrochemical behaviour was studied by cyclic and linear sweep voltammetries. • Anodic dissolution of Cu and cathodic deposition of Cu, Nb and Cu/Nb were studied. • The Cu, Nb and Cu/Nb deposits were characterised through SEM and EDX analyses. • The characteristic length of the deposits ranges between 50 and 100 nm.

Current trends in electrochemical sensing and biosensing of DNA methylation.

Science.gov (United States)

Krejcova, Ludmila; Richtera, Lukas; Hynek, David; Labuda, Jan; Adam, Vojtech

2017-11-15

DNA methylation plays an important role in physiological and pathological processes. Several genetic diseases and most malignancies tend to be associated with aberrant DNA methylation. Among other analytical methods, electrochemical approaches have been successfully employed for characterisation of DNA methylation patterns that are essential for the diagnosis and treatment of particular diseases. This article discusses current trends in the electrochemical sensing and biosensing of DNA methylation. Particularly, it provides an overview of applied electrode materials, electrode modifications and biorecognition elements applications with an emphasis on strategies that form the core DNA methylation detection approaches. The three main strategies as (i) bisulfite treatment, (ii) cleavage by restriction endonucleases, and (iii) immuno/affinity reaction were described in greater detail. Additionally, the availability of the reviewed platforms for early cancer diagnosis and the approval of methylation inhibitors for anticancer therapy were discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

The Aqueous Electrochemical Response of TiC–Stainless Steel Cermets

Directory of Open Access Journals (Sweden)

Chukwuma Onuoha

2018-05-01

Full Text Available A family of TiC–stainless steel ceramic–metal composites, or cermets, has been developed in the present study, using steel grades of 304 L, 316 L, or 410 L as the binder phase. Melt infiltration was used to prepare the cermets, with the steel binder contents varying between 10–30 vol. %. The corrosion behaviour was evaluated using a range of electrochemical techniques in an aqueous solution containing 3.5 wt. % NaCl. The test methods included potentiodynamic, cyclic, and potentiostatic polarisation. The corroded samples were subsequently characterised using scanning electron microscopy (SEM and energy dispersive X-ray spectroscopy (EDS, while the post-corrosion solutions were analysed using inductively coupled plasma optical emission spectroscopy (ICP-OES to determine the residual ionic and particulate material removed from the cermets during electrochemical testing. It was demonstrated that the corrosion resistance was enhanced through decreasing the steel binder content, which arises due to the preferential dissolution of the binder phase, while the TiC ceramic remains largely unaffected. Increasing corrosion resistance was observed in the sequence TiC-304 L > TiC-316 L > TiC-410 L.

Nanostructured stannic oxide: Synthesis and characterisation for potential energy storage applications

Science.gov (United States)

Dodoo-Arhin, D.; Nuamah, R. A.; Jain, P. K.; Obada, D. O.; Yaya, A.

2018-06-01

SnO2 nanoparticles were synthesized using the hydrothermal technique. Well crystalline particles with different morphologies and crystallite size in the range of 2 nm-10 nm were obtained by using Urea and Soduim Borohydride as reducing agents, and deploying Dioctyl Sulfosuccinate Sodium Salt (AOT) and Cetyl Trimethyl ammonium bromide (CTAB) as the surfactants. Samples have been characterised by X-ray diffraction, Scanning Electron microscopy, Energy Dispersive X-ray spectroscopy, specific surface area, porosity, and Fourier Transform Infrared spectroscopy. Preliminary studies on the potential electrochemical properties of the as-produced nanoparticles were investigated using cyclic voltammetry, electrochemical impedance spectroscopy and potentiostatic charge-discharge in aqueous KOH electrolyte. The surfactant and reducing agents used in the synthesis procedure of SnO2 nanoparticles influenced the particle size and the morphology, which in turn influenced the capacitance of the SnO2 nanoparticles. The SnO2 electrode material showed pseudocapacitor properties with a maximum capacitance value of 1.6 Fg-1 at a scan rate of 5 mVs-1, an efficiency of 52% at a current of 1 mA and a maximum capacitance retention of about 40% after 10 cycles at a current of 1 mA. From the Nyquist plot, The ESR for the samples increase accordingly as SCA (31.5 Ω) < SAA (31.85 Ω) < SE (36.3 Ω) < SAT (36.92 Ω) < SCT (40.41 Ω) < SA < SC (53.97 Ω). These values are a confirmation of the low capacitance, efficiencies and capacitance retention recorded. The results obtained demonstrate the potential electrochemical storage applications of SnO2 nanoparticles without the addition of conductive materials.

Electrochemically active manganese oxides: structural modelling, modifications induced by thermal processing and photon insertion

International Nuclear Information System (INIS)

Ripert, Michel

1990-01-01

The objective of this research study is to understand the mechanism of proton insertion into manganese dioxide. It comprised the performances of in situ discharges of two commercial samples in an electrochemical cell designed for this purpose. In order to characterise the structure of electrochemically active manganese dioxides, and particularly to elucidate the orthorhombic-hexagonal dilemma, the author proposes a crystalline-chemical approach which comprises the development of a unique structural model which takes the structure of all forms of electrochemically active manganese dioxides into account, and a numerical simulation of diffraction diagrams (X rays and neutrons) of these structures. The development of this modelling results in the development of a method which allows, from experimental diffraction diagrams, characteristic structural parameters of each sample of EMD (electrolytic manganese dioxide) or CMD (chemical manganese dioxide) to be obtained. Moreover, the observation of the structural evolution of the dioxide is possible by using in situ neutron diffraction. Reduction has been studied by using slow potential scanning voltammetry. By using these both techniques (neutron diffraction and voltammetry), it is possible to explain the structural mechanism of reduction of MnO_2 and to show the origin of the non-reversibility of the proton/MnO_2 system, to quantitatively explain the shape voltammetry curves, and to highlight experimentally for the first time the different sites of insertion of the proton

Studies on direct and indirect electrochemical immunoassays

OpenAIRE

Buckley, Eileen

1989-01-01

Two approaches to electrochemical immunoassay are reported. The first approach was an indirect method, involving an electroactive, enzyme-catalysed, substrate to product reaction. Conditions were optimised for the amperometric detection of para-aminophenol, the electroactive product of the alkaline phosphatase catalysed hydrolysis of a new substrate, p-aminophenylphosphate, after separation by HPLC. The second approach involved the direct electrochemical detection of an immunoglo...

Electrochemical studies of ruthenium compounds

International Nuclear Information System (INIS)

Kumar Ghosh, B.; Chakravorty, A.

1989-01-01

In many ways the chemistry of transition metals is the chemistry of multiple oxidation states and the associated redox phenomena. If a particular element were to be singeld out to illustrate this viewpoint, a model choice would be ruthenium - an element that is directly or indirectly the active centre of a plethora of redox phenomena encompassing ten different oxidation states and a breathtaking diversity of structure and bonding. In the present review the authors are primarily concerned with the oxidation states of certain ligands coordinated to ruthenium. This choice is deliberate since this is one area where the unique power of electrochemical methods is splendidly revealed. Without these methods, development in this area would have been greatly hampered. A brief summary of metal oxidation states is also included as a prelude to the main subject of this review. The authors have generally emphasize the information derived which is of chemical interest leaving the details of formal electrochemical arguments in the background. The authors have reviewed the pattern and systematics of ligand redox in ruthenium complexes. The synergistic combination of electrochemical and spectroscopic methods have vastly increased our understanding of ligand phenomena during the last 15 years or so. This in turn has led to better understanding and new developments in other fields. Photophysics and photochemistry could be cited as examples. (author). 176 refs.; 10 figs.; 10 tabs

Nature of the Electrochemical Properties of Sulphur Substituted LiMn2O4 Spinel Cathode Material Studied by Electrochemical Impedance Spectroscopy

Directory of Open Access Journals (Sweden)

Monika Bakierska

2016-08-01

Full Text Available In this work, nanostructured LiMn2O4 (LMO and LiMn2O3.99S0.01 (LMOS1 spinel cathode materials were comprehensively investigated in terms of electrochemical properties. For this purpose, electrochemical impedance spectroscopy (EIS measurements as a function of state of charge (SOC were conducted on a representative charge and discharge cycle. The changes in the electrochemical performance of the stoichiometric and sulphur-substituted lithium manganese oxide spinels were examined, and suggested explanations for the observed dependencies were given. A strong influence of sulphur introduction into the spinel structure on the chemical stability and electrochemical characteristic was observed. It was demonstrated that the significant improvement in coulombic efficiency and capacity retention of lithium cell with LMOS1 active material arises from a more stable solid electrolyte interphase (SEI layer. Based on EIS studies, the Li ion diffusion coefficients in the cathodes were estimated, and the influence of sulphur on Li+ diffusivity in the spinel structure was established. The obtained results support the assumption that sulphur substitution is an effective way to promote chemical stability and the electrochemical performance of LiMn2O4 cathode material.

Electrochemical behaviour of titanium coated stainless steel by r.f. sputtering in synthetic sweat solutions for electrode applications

International Nuclear Information System (INIS)

Fonseca, C.; Vaz, F.; Barbosa, M.A.

2004-01-01

The r.f. sputtering technique was used to deposit titanium thin films on stainless steel substrates, aiming at the application of the coated samples as skin contact materials for 'dry' active electrodes. In this work the electrochemical behaviour of the coated samples was investigated in synthetic sweat solutions and their performance was compared with that of uncoated stainless steel and bulk titanium. The characterisation of the samples was carried out by electrochemical techniques and scanning electron microscopy. The coated samples displayed corrosion resistance values in synthetic sweat solutions much higher than stainless steel samples and of the same order of the values measured for bulk titanium in the same conditions

Structural, spectroscopic and electrochemical study of V substituted ...

Indian Academy of Sciences (India)

Administrator

Electrochemical impedance studies showed that ionic conductivity is high for x = 0∙10 composition. a.c. and ... ground in an agate mortar in the presence of methanol for .... tion peaks are stabilized at 2∙41 V. The oxidation peaks are observed ...

ELECTROCHEMICAL FINGERPRINT STUDIES OF SELECTED MEDICINAL PLANTS RICH IN FLAVONOIDS.

Science.gov (United States)

Konieczyński, Paweł

2015-01-01

The combination of a size-exclusion column (SEC) with electrochemical (voltammetric) detection at a boron-doped diamond electrode (BDDE) was applied for studying the correlations between electroactive Cu and Fe species with phenolic groups of flavonoids. For comparison with electrochemical results, SEC-HPLC-DAD detection was used. The studied plant material comprised of: Betula verrucosa Ehrh., Equisetun arvense L., Polygonum aviculare L., Viola tricolor L., Crataegus oxyacantha L., Sambucus nigra L. and Helichrysum arenarium (L.) Moench. Based upon the results, high negative correlation was found for the chromatographic peak currents at 45 min with the sum of Cu and Fe for the aqueous extracts of Sambucus, Crataegus and Betula species, and for the peak currents at 65 min of the aqueous extracts of Sambucus, Crataegus, Helichrysum and Betula botanical species. This behavior confirms that it is mainly the flavonoids with easily oxidizable phenolic groups which are strongly influenced by the presence of Cu and Fe. Moreover, the electrochemical profiles obtained thanks to the use of HPLC hyphenated with voltammetric detection can be potentially applied for fingerprint studies of the plant materials used in medicine.

Development and characterisation of a novel composite electrode material consisting of poly(3,4-ethylenedioxythiophene) including Au nanoparticles

International Nuclear Information System (INIS)

Zanardi, C.; Terzi, F.; Pigani, L.; Heras, A.; Colina, A.; Lopez-Palacios, J.; Seeber, R.

2008-01-01

Composite material consisting of poly(3,4-ethylenedioxythiophene) (PEDOT), including Au nanoparticles encapsulated by N-dodecyl-N,N-dimethyl-3-ammonium-1-propanesulphonate (SB12) is synthesised by constant-current method on ITO glass, in aqueous medium, leading to an electrode coating. The synthesis process is followed by UV-vis spectroelectrochemistry, both in normal-beam and in parallel-beam configurations. Under the same experimental conditions PEDOT is also synthesised by electropolymerisation only in the presence of LiClO 4 supporting electrolyte, as well in solutions also containing SB12. The data relative to the electrosynthesis of the three materials are compared. The composite material based on the conductive polymer matrix including Au nanoparticles has been characterised by SEM, TEM, ICP, Raman and UV-vis spectroscopies. The behaviour of the three different electrode coatings with respect to p-doping process has been studied by conventional electrochemical techniques and by potentiostatic and potentiodynamic UV-vis spectroelectrochemical methods. Conclusions are drawn out about the effect of the presence of the surfactant and of Au nanoparticles on the electrochemical properties of the electrode system

First Principle simulations of electrochemical interfaces - a DFT study

DEFF Research Database (Denmark)

Ahmed, Rizwan

for the whole system to qualify as a proper electrochemical interface. I have also contributed to the model, which accounts for pH in the first principle electrode-electrolyte interface simulations. This is an important step forward, since electrochemical reaction rate and barrier for charge transfer can......In this thesis, I have looked beyond the computational hydrogen electrode (CHE) model, and focused on the first principle simulations which treats the electrode-electrolyte interfaces explicitly. Since obtaining a realistic electrode-electrolyte interface was difficult, I aimed to address various...... challenges regarding first principle electrochemical interface modeling in order to bridge the gap between the model interface used in simulations and real catalyst at operating conditions. Atomic scale insight for the processes and reactions that occur at the electrochemical interface presents a challenge...

Electrochemical Studies of Camptothecin and Its Interaction with Human Serum Albumin

OpenAIRE

Zhao, Jing; Zheng, Xiaofeng; Xing, Wei; Huang, Junyi; Li, Genxi

2007-01-01

Camptothecin, an anticancer component from Camptotheca acuminate, may interact with human serum albumin (HSA) at the subdomain IIA (site I), and then convert to its inactive form(carboxylate form). In this paper, the detailed electrochemical behaviors of camptothecin at a pyrolytic graphite electrode is presented. The interaction between camptothecin and HSA is also studied by electrochemical technique. By comparing with bovine serum albumin (BSA), which is highly homologous to HSA, we prove ...

Alizarin Red S as an electrochemical indicator for saccharide recognition

Energy Technology Data Exchange (ETDEWEB)

Schumacher, Soeren, E-mail: soeren.schumacher@ibmt.fraunhofer.de [Fraunhofer Institute for Biomedical Engineering, Am Muehlenberg 13, 14476 Potsdam (Germany); Nagel, Thomas; Scheller, Frieder W.; Gajovic-Eichelmann, Nenad [Fraunhofer Institute for Biomedical Engineering, Am Muehlenberg 13, 14476 Potsdam (Germany)

2011-07-30

Graphical abstract: Display Omitted Highlights: > Transfer of the established Alizarin Red S (ARS) for saccharide-boronic acid interaction to electrochemistry. > Investigation of electrochemical behaviour of ARS and its interaction with phenylboronic acid at pH 7.4. > Through addition of fructose the ARS was displaced. > Displaced ARS could be monitored electrochemically corresponding to the used fructose concentration. - Abstract: In addition to the well-established spectroscopic Alizarin Red S (ARS) assay for the determination of binding constants between arylboronic acids and different saccharides, we report the use of ARS as a reporter in an electrochemical set-up. The electrochemical properties of ARS, the binding to phenyl boronic acid (PBA) and the competition with fructose in phosphate buffer at pH 7.4 were investigated by cyclic voltammetry (CV). By choosing a negative scan direction (starting at +0.2 V), a quasi-reversible process was detected at E{sup 0}' = -0.59V with {Delta}E{sub p} = 0.1V. An irreversible oxidation peak at +0.42 V could also be detected. These peaks are characterised both as a 2-proton-2-electron transfer and corresponds to the oxidation and reduction of the anthraquinone or the ortho-quinone moiety. After addition of phenylboronic acid a new oxidation peaks occurred at -0.42 V which correlates with the ARS-PBA interaction. The peak current increased with increasing phenylboronic acid concentration according to the release of BA and formation of the ARS-PBA ester. After addition of fructose the peak current decreases again, in proportion to the fructose concentration, enabling the use of ARS as an electrochemical reporter for fructose detection up to 50 mM. Also the interaction with other cis-diol containing compounds such as sorbitol, mannitol, glucose and mannose was investigated and a dependence based on already published binding constants to phenylboronic acid could be shown.

Alizarin Red S as an electrochemical indicator for saccharide recognition

International Nuclear Information System (INIS)

Schumacher, Soeren; Nagel, Thomas; Scheller, Frieder W.; Gajovic-Eichelmann, Nenad

2011-01-01

Graphical abstract: Display Omitted Highlights: → Transfer of the established Alizarin Red S (ARS) for saccharide-boronic acid interaction to electrochemistry. → Investigation of electrochemical behaviour of ARS and its interaction with phenylboronic acid at pH 7.4. → Through addition of fructose the ARS was displaced. → Displaced ARS could be monitored electrochemically corresponding to the used fructose concentration. - Abstract: In addition to the well-established spectroscopic Alizarin Red S (ARS) assay for the determination of binding constants between arylboronic acids and different saccharides, we report the use of ARS as a reporter in an electrochemical set-up. The electrochemical properties of ARS, the binding to phenyl boronic acid (PBA) and the competition with fructose in phosphate buffer at pH 7.4 were investigated by cyclic voltammetry (CV). By choosing a negative scan direction (starting at +0.2 V), a quasi-reversible process was detected at E 0 ' = -0.59V with ΔE p = 0.1V. An irreversible oxidation peak at +0.42 V could also be detected. These peaks are characterised both as a 2-proton-2-electron transfer and corresponds to the oxidation and reduction of the anthraquinone or the ortho-quinone moiety. After addition of phenylboronic acid a new oxidation peaks occurred at -0.42 V which correlates with the ARS-PBA interaction. The peak current increased with increasing phenylboronic acid concentration according to the release of BA and formation of the ARS-PBA ester. After addition of fructose the peak current decreases again, in proportion to the fructose concentration, enabling the use of ARS as an electrochemical reporter for fructose detection up to 50 mM. Also the interaction with other cis-diol containing compounds such as sorbitol, mannitol, glucose and mannose was investigated and a dependence based on already published binding constants to phenylboronic acid could be shown.

Electrochemical performance studies of MnO2 nanoflowers recovered from spent battery

International Nuclear Information System (INIS)

Ali, Gomaa A.M.; Tan, Ling Ling; Jose, Rajan; Yusoff, Mashitah M.; Chong, Kwok Feng

2014-01-01

Highlights: • MnO 2 is recovered from spent zinc–carbon batteries as nanoflowers structure. • Recovered MnO 2 nanoflowers show high specific capacitance. • Recovered MnO 2 nanoflowers show stable electrochemical cycling up to 900 cycles. • Recovered MnO 2 nanoflowers show low resistance in EIS data. - Abstract: The electrochemical performance of MnO 2 nanoflowers recovered from spent household zinc–carbon battery is studied by cyclic voltammetry, galvanostatic charge/discharge cycling and electrochemical impedance spectroscopy. MnO 2 nanoflowers are recovered from spent zinc–carbon battery by combination of solution leaching and electrowinning techniques. In an effort to utilize recovered MnO 2 nanoflowers as energy storage supercapacitor, it is crucial to understand their structure and electrochemical performance. X-ray diffraction analysis confirms the recovery of MnO 2 in birnessite phase, while electron microscopy analysis shows the MnO 2 is recovered as 3D nanostructure with nanoflower morphology. The recovered MnO 2 nanoflowers exhibit high specific capacitance (294 F g −1 at 10 mV s −1 ; 208.5 F g −1 at 0.1 A g −1 ) in 1 M Na 2 SO 4 electrolyte, with stable electrochemical cycling. Electrochemical data analysis reveal the great potential of MnO 2 nanoflowers recovered from spent zinc–carbon battery in the development of high performance energy storage supercapacitor system

Molten salt engineering for thorium cycle. Electrochemical studies as examples

International Nuclear Information System (INIS)

Ito, Yasuhiko

1998-01-01

A Th-U nuclear energy system utilizing accelerator driven subcritical molten salt breeder reactor has several advantages compared to conventional U-Pu nuclear system. In order to obtain fundamental data on molten salt engineering of Th-U system, electrochemical study was conducted. As the most primitive simulated study of beam irradiation of molten salt, discharge electrolysis was investigated in molten LiCl-KCl-AgCl system. Stationary discharge was generated under atmospheric argon gas and fine Ag particles were obtained. Hydride ion (H - ) behavior in molten salts was also studied to predict the behavior of tritide ion (T - ) in molten salt fuel. Finally, hydrogen behavior in metals at high temperature was investigated by electrochemical method, which is considered to be important to confine and control tritium. (author)

A perspective on the structural studies of inner membrane electrochemical potential-driven transporters.

Science.gov (United States)

Lemieux, M Joanne

2008-09-01

Electrochemical potential-driven transporters represent a vast array of proteins with varied substrate specificities. While diverse in size and substrate specificity, they are all driven by electrochemical potentials. Over the past five years there have been increasing numbers of X-ray structures reported for this family of transporters. Structural information is available for five subfamilies of electrochemical potential-driven transporters. No structural information exists for the remaining 91 subfamilies. In this review, the various subfamilies of electrochemical potential-driven transporters are discussed. The seven reported structures for the electrochemical potential-driven transporters and the methods for their crystallization are also presented. With a few exceptions, overall crystallization trends have been very similar for the transporters despite their differences in substrate specificity and topology. Also discussed is why the structural studies on these transporters were successful while others are not as fruitful. With the plethora of transporters with unknown structures, this review provides incentive for crystallization of transporters in the remaining subfamilies for which no structural information exists.

Effect of varying the amount of binder on the electrochemical characteristics of palm shell activated carbon

Science.gov (United States)

Imam Maarof, Hawaiah; Daud, Wan Mohd Ashri Wan; Kheireddine Aroua, Mohamed

2017-06-01

Polytetrafluoroethylene (PTFE) is among the most common binders used in the fabrication of an electrode, which is used for various electrochemical applications such as desalination, water purification, and wastewater treatment. In this study, the amount of the binder was varied at 10, 20, 30, and 40 wt% of the total mass of palm shell activated carbon (PSAC). The PSAC was used as the active material and carbon black was used as the conductive agent. The effect of different amounts of binder was observed by evaluating the electrochemical characteristics of the electrode through cyclic voltammetry (CV) and potentio electrochemical spectroscopy (PEIS). The CV analysis was employed to determine the geometric area normalised electrode double layer capacitance, CE , and the electrode reaction of the prepared electrode. Meanwhile, the common redox probe, ferro/ferricyanide in 0.5 M NaCl, was employed to estimate the electron transfer resistance through PEIS. The electrochemical characterisation proved that the optimum amount of PTFE was 20 wt% for the 4:1 ratio of active material to conductive agent. On increasing the amount of the binder to 30 wt% and 40 wt%, the estimated value of CE decreased and remained almost equivalent. Adding more than 30 wt% of binder resulted in pore blockage and reduced the available active site on the PSAC electrode. In addition, the electron transfer resistance of the prepared electrode was found to be in the range of 4-5 Ω·cm2.

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.

Radiological characterisation - Know your objective

International Nuclear Information System (INIS)

Lindow, Veronica; Moeller, Jennifer

2012-01-01

When developing a programme for mapping the radiological characteristics of a facility to be decommissioned it is important to take into account the objectives of the programme. Will the results be used to plan for radiological control and selection of appropriate decontamination and dismantling techniques? Will the radiological inventory be used for dimensioning of future waste repositories? These are two examples of the applications for such studies, which could require that a radiological characterisation programme be adapted to provide the data appropriate to the intended use. The level of detail and scope needed for a radiological characterisation will also vary depending on how the data will be used. An application to free-release a facility requires a comprehensive survey and well documented analysis in order to ensure that no radioactive contamination above prescribed levels is present. A bounding calculation to determine the maximum anticipated volumes and activity of radioactive waste requires a different approach. During the past few years, older decommissioning studies for the Swedish nuclear power plants have been updated (or are in the process of being updated). The decommissioning study's main purpose is to estimate the cost for decommissioning. The cost estimation is based on material and activity inventories, which in turn is based on previous and, in some cases, updated radiological characterisations of the facilities. The radiological inventory is an important part of the study as it affects the cost of decommissioning but also the uncertainties and accuracy of the cost estimation. The presentation will discuss the challenges in specifying a radiological characterisation programme with multiple objectives, together with insights on how data delivered can be applied to yield results suitable for the intended purpose, without introducing excessive conservatism. The intent of the presentation is to define issues that can be of use in various aspects

Electrochemical Oxidation of Propene with a LSF15/CGO10 Electrochemical Reactor

DEFF Research Database (Denmark)

Ippolito, Davide; Kammer Hansen, Kent

2014-01-01

A porous electrochemical reactor, made of La0.85Sr0.15FeO3 (LSF) as electrode and Ce0.9Gd0.1O1.95 (CGO) as electrolyte, was studied for the electrochemical oxidation of propene over a wide range of temperatures. Polarization was found to enhance propene oxidation rate. Ce0.9Gd0.1O1.95 was used...... as infiltration material to enhance the effect of polarization on propene oxidation rate, especially at low temperatures. The influence of infiltrated material, as a function of heat treatment, on the reactor electrochemical behavior has been evaluated by using electrochemical impedance spectroscopy...... in suppressing the competing oxygen evolution reaction and promoting the oxidation of propene under polarization, with faradaic efficiencies above 70% at 250◦C. © 2014 The Electrochemical Society....

A study of passivation/depassivation of carbon steel; electrochemical impedance spectrocopy vs. potential noise fluctuations

International Nuclear Information System (INIS)

Roberge, P.R.; Halliop, E.; Sastri, V.S.

1992-01-01

A technique based on recording corrosion potential fluctuations generated by corroding electrodes was used under open-circuit conditions to study passivation and depassivation of carbon steel. Quantification of the electrochemical signal in terms of the pitting corrosion rate has been attempted. The amplitude of electrochemical noise signals was analyzed under different pitting conditions and correlated to polarization resistance values obtained from the electrochemical impedance spectra. The automatic statistical data analysis of electrochemical impedance data points has been successfully applied to calculate polarization resistance values and other interesting characteristics of such measurements

Revisiting the electrochemical impedance spectroscopy of magnesium with online inductively coupled plasma atomic emission spectroscopy.

Science.gov (United States)

Shkirskiy, Viacheslav; King, Andrew D; Gharbi, Oumaïma; Volovitch, Polina; Scully, John R; Ogle, Kevin; Birbilis, Nick

2015-02-23

The electrochemical impedance of reactive metals such as magnesium is often complicated by an obvious inductive loop with decreasing frequency of the AC polarising signal. The characterisation and ensuing explanation of this phenomenon has been lacking in the literature to date, being either ignored or speculated. Herein, we couple electrochemical impedance spectroscopy (EIS) with online atomic emission spectroelectrochemistry (AESEC) to simultaneously measure Mg-ion concentration and electrochemical impedance spectra during Mg corrosion, in real time. It is revealed that Mg dissolution occurs via Mg(2+) , and that corrosion is activated, as measured by AC frequencies less than approximately 1 Hz approaching DC conditions. The result of this is a higher rate of Mg(2+) dissolution, as the voltage excitation becomes slow enough to enable all Mg(2+) -enabling processes to adjust in real time. The manifestation of this in EIS data is an inductive loop. The rationalisation of such EIS behaviour, as it relates to Mg, is revealed for the first time by using concurrent AESEC. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microfluidic platform for studying the electrochemical reduction of carbon dioxide

Science.gov (United States)

Whipple, Devin Talmage

Diminishing supplies of conventional energy sources and growing concern over greenhouse gas emissions present significant challenges to supplying the world's rapidly increasing demand for energy. The electrochemical reduction of carbon dioxide has the potential to address many of these issues by providing a means of storing electricity in chemical form. Storing electrical energy as chemicals is beneficial for leveling the output of clean, but intermittent renewable energy sources such as wind and solar. Electrical energy stored as chemicals can also be used as carbon neutral fuels for portable applications allowing petroleum derived fuels in the transportation sector to be replaced by more environmentally friendly energy sources. However, to be a viable technology, the electrochemical reduction of carbon dioxide needs to have both high current densities and energetic efficiencies (Chapter 1). Although many researchers have studied the electrochemical reduction of CO2 including parameters such as catalysts, electrolytes and temperature, further investigation is needed to improve the understanding of this process and optimize the performance (Chapter 2). This dissertation reports the development and validation of a microfluidic reactor for the electrochemical reduction of CO2 (Chapter 3). The design uses a flowing liquid electrolyte instead of the typical polymer electrolyte membrane. In addition to other benefits, this flowing electrolyte gives the reactor great flexibility, allowing independent analysis of each electrode and the testing of a wide variety of conditions. In this work, the microfluidic reactor has been used in the following areas: • Comparison of different metal catalysts for the reduction of CO2 to formic acid and carbon monoxide (Chapter 4). • Investigation of the effects of the electrolyte pH on the reduction of CO2 to formic acid and carbon monoxide (Chapter 5). • Study of amine based electrolytes for lowering the overpotentials for CO2

Characterisation of biosynthesised silver nanoparticles by scanning electrochemical microscopy (SECM) and voltammetry.

Science.gov (United States)

Battistel, Dario; Baldi, Franco; Gallo, Michele; Faleri, Claudia; Daniele, Salvatore

2015-01-01

Silver nanoparticles (AgNPs) were biosynthesised by a Klebsiella oxytoca strain BAS-10, which, during its growth, is known to produce a branched exopolysaccharide (EPS). Klebsiella oxytoca cultures, treated with AgNO3 and grown under either aerobic or anaerobic conditions, produced silver nanoparticles embedded in EPS (AgNPs-EPS) containing different amounts of Ag(0) and Ag(I) forms. The average size of the AgNPs-EPS was determined by transmission electron microscopy, while the relative abundance of Ag(0)- or Ag(I)-containing AgNPs-EPS was established by scanning electrochemical microscopy (SECM). Moreover, the release of silver(I) species from the various types of AgNPs-EPS was investigated by combining SECM with anodic stripping voltammetry. These measurements allowed obtaining information on the kinetic of silver ions release from AgNPs-EPS and their concentration profiles at the substrate/water interface. Copyright © 2014 Elsevier B.V. All rights reserved.

Electrochemically adsorbed Pb on Ag (111) studied with grazing- incidence x-ray scattering

International Nuclear Information System (INIS)

Kortright, J.B.; Ross, P.N.; Melroy, O.R.; Toney, M.F.; Borges, G.L.; Samant, M.G.

1989-04-01

Grazing-incidence x-ray scattering studies of the evolution of electrochemically deposited layers of lead on silver (111) as a function of applied electrochemical potential are presented. Measurements were made with the adsorbed layers in contact with solution in a specially designed sample cell. The observed lead structures are a function of the applied potential and range from an incommensurate monolayer, resulting from underpotential deposition, to randomly oriented polycrystalline bulk lead, resulting from lower deposition potentials. These early experiments demonstrate the ability of in situ x-ray diffraction measurements to determine structures associated with electrochemical deposition. 6 refs., 4 figs

DFT based study of transition metal nano-clusters for electrochemical NH3 production

DEFF Research Database (Denmark)

Howalt, Jakob Geelmuyden; Bligaard, Thomas; Rossmeisl, Jan

2013-01-01

Theoretical studies of the possibility of producing ammonia electrochemically at ambient temperature and pressure without direct N2 dissociation are presented. Density functional theory calculations were used in combination with the computational standard hydrogen electrode to calculate the free...... for electrochemical ammonia production. The competing hydrogen evolution reaction has also been analyzed for comparison....

An extended characterisation theorem for quantum logics

International Nuclear Information System (INIS)

Sharma, C.S.; Mukherjee, M.K.

1977-01-01

Two theorems are proved. In the first properties of an important mapping from an orthocomplemented lattice to itself are studied. In the second the characterisation theorem of Zierler (Pacific J. Math.; 11:1151 (1961)) is extended to obtain a very useful theorem characterising orthomodular lattices. Since quantum logics are merely sigma-complete orthomodular lattices, the principal result is, for application in quantum physics, a characterisation theorem for quantum logics. (author)

Characterisation of Tmmmian Local Sorghmn Varieties

African Journals Online (AJOL)

Many local varieties of sorghum grown in Tanzania have not been characterised in terms of their end uses. This study was conducted to characterise 14 such varieties. Three improved varieties commonly grown in this country were includedfor comparison. Physical analyses that included 100-grain weight, percent dehulling ...

Effect of impurities on structural and electrochemical properties of the Ni-YSZ interface

DEFF Research Database (Denmark)

Jensen, Karin Vels; Wallenberg, R.; Chorkendorff, I.

2003-01-01

. The results were compared to earlier investigations of a less pure nickel/YSZ interface. The pure interface developed different structures depending on whether or not the samples were polarised. Despite,the purity of the nickel, impurities were found in the interfacial region. The pure electrodes......The changes in interface structure and chemical composition of a 99.995% pure nickel/yttria-stabilised zirconia (YSZ) interface were examined after heat treatment at 1000degreesC in 97% H-2/3% H2O with and without polarisation. Impedance spectroscopy was used for electrochemical characterisation...

Design of an electrochemical cell for in situ XAS studies

Energy Technology Data Exchange (ETDEWEB)

Watanabe, N. [Instituto de Quimica, Universidade Estadual de Campinas (UNICAMP), Box 6154, CEP 13083-970, Campinas, SP (Brazil); Morais, J. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Goncalves, 9500, Bairro Agronomia, CP 15051, CEP 91501-970, Porto Alegre, RS (Brazil); Alves, M.C.M. [Instituto de Quimica, Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Goncalves, 9500, Bairro Agronomia, CP 15003, CEP 91501-970, Porto Alegre, RS (Brazil)], E-mail: maria@iq.ufrgs.br

2007-05-15

In situ X-ray absorption spectroscopy (XAS) studies have been carried out on the electrochemical insertion of Co metal particles in polypyrrole. This has become possible due to the development of an electrochemical cell to allow XAS studies in fluorescence geometry under steady-state conditions. The experimental set-up allows the in situ monitoring of the structural and electronic changes of the selected atom in a matrix. The project of the electrochemical cell is presented with the results obtained at different stages of the electrochemical process. XANES and EXAFS results showed that the initial stage of the cobalt insertion in polypyrrole took place in an ionic form, like [-[(C{sub 4}H{sub 2}N){sub 3}CH{sub 3}(CH{sub 2}){sub 11}OSO{sub 3}{sup -}]{sub 6}Co{sup 2+}] with posterior reduction to a metallic form. The quantitative analysis of the first shell shows that, at -0.60 V, the cobalt atoms are surrounded by 6 ({+-}0.5) atoms located at 2.12 ({+-}0.05) A with a large Debye-Waller factor ({sigma}{sup 2}) value of 0.0368 ({+-}0.0074). At -0.80 V, two distances of R = 1.99 ({+-}0.01) and R = 2.50 ({+-}0.01) A show the coexistence of cobalt in the oxidized and reduced (Co{sup 0}) forms. The Co-Co distance corresponds to that of bulk cobalt. At -1.20 V, the obtained values of N = 12 ({+-}0.5) and R = 2.56 ({+-}0.01) A and a Debye-Waller factor of 0.0176 ({+-}0.0004) suggest the formation of metallic cobalt in a quite disordered form.

Indoor atmospheric corrosion of historical ferrous alloys. System characterisation, mechanisms and modelling discussion

International Nuclear Information System (INIS)

Monnier, J.

2008-12-01

Understanding the mechanisms of indoor atmospheric corrosion in iron alloys is of primary importance in several fields, including for the conservation of Middle Ages monuments or the long term storage of nuclear waste. In this research, a double approach was developed, combining fine characterisation of corrosion systems and design of experiments to answers specific questions related to mechanisms understanding. Iron indoor atmospheric corrosion was investigated on samples coming from the reinforcing chain of the Amiens cathedral (15. century). In the first stage, the corrosion system has been extensively characterised from the macroscopic to the nano-metric scale. In particular, structural micro-analysis (μ-Raman, μ-XRD, μ-XAS) has been used to locate, identify and quantify the oxidised phases. Rust layers are composed of a matrix of nano-metric goethite, with low quantities of lepidocrocite and akaganeite mostly located in the extern part of the corrosion system. In addition, clear marblings are dispersed in the matrix, which are sometimes connected with the metal core. Although these may contain maghemite, these marblings are generally made of ferri-hydrite/feroxyhite phases. In the second stage, specific experiments have been carried out in an unsaturated marked medium to locate oxygen reduction sites in the rust layers. Several cases were evidenced, depending on the rust layer morphology. In addition, reduction processes of model phases have been studied in situ, using an electrochemical cell coupled with structural characterisation techniques. This combination highlighted the influence of reduction mode and pH on the type of reduced phase formed. From the obtained results, several mechanisms are proposed to explain the long term indoor atmospheric corrosion of iron, including rust layers morphology and phases properties. The different hypotheses have been integrated in a proposed method to diagnosis ancient ferrous systems stability. These hypotheses also

Electrochemical reduction of NOx

DEFF Research Database (Denmark)

Traulsen, Marie Lund

NO and NO2 (collectively referred to as NOx) are air pollutants, and the largest single contributor to NOx pollution is automotive exhaust. This study investigates electrochemical deNOx, a technology which aims to remove NOx from automotive diesel exhaust by electrochemical reduction of NOx to N2...... and O2. The focus in this study is on improving the activity and selectivity of solid oxide electrodes for electrochemical deNOx by addition of NOx storage compounds to the electrodes. Two different composite electrodes, La0.85Sr0.15MnO3-δ-Ce0.9Gd0.1O1.95 (LSM15-CGO10) and La0.85Sr0.15FeO3-δ-Ce0.9Gd0.1O......1.95 (LSF15-CGO10), have been investigated in combination with three different NOx storage compounds: BaO, K2O and MnOx. The main focus in the investigation has been on conversion measurements and electrochemical characterization, the latter by means of electrochemical impedance spectroscopy...

Electrochemical Study of Bromide in the Presence of 1,3-Indandione. Application to the Electrochemical Synthesis of Bromo Derivatives of 1,3-Indandione

OpenAIRE

Nematollahi, D.; Akaberi, N.

2001-01-01

The electrochemical oxidation of bromide in the presence of 1,3-indandione (1) in water/acetic acid and methanol/acetic acid mixtures has been studied by cyclic voltammetry and controlled-potential coulometry. The results indicate the participation of 1,3-indandione in the bromination reaction. On the basis of the electroanalytical and preparative results a reaction mechanism including electron transfer, chemical reaction and regeneration of bromide was discussed. The electrochemical synthesi...

Real-time studies of battery electrochemical reactions inside a transmission electron microscope.

Energy Technology Data Exchange (ETDEWEB)

Leung, Kevin; Hudak, Nicholas S.; Liu, Yang; Liu, Xiaohua H.; Fan, Hongyou; Subramanian, Arunkumar; Shaw, Michael J.; Sullivan, John Patrick; Huang, Jian Yu

2012-01-01

We report the development of new experimental capabilities and ab initio modeling for real-time studies of Li-ion battery electrochemical reactions. We developed three capabilities for in-situ transmission electron microscopy (TEM) studies: a capability that uses a nanomanipulator inside the TEM to assemble electrochemical cells with ionic liquid or solid state electrolytes, a capability that uses on-chip assembly of battery components on to TEM-compatible multi-electrode arrays, and a capability that uses a TEM-compatible sealed electrochemical cell that we developed for performing in-situ TEM using volatile battery electrolytes. These capabilities were used to understand lithiation mechanisms in nanoscale battery materials, including SnO{sub 2}, Si, Ge, Al, ZnO, and MnO{sub 2}. The modeling approaches used ab initio molecular dynamics to understand early stages of ethylene carbonate reduction on lithiated-graphite and lithium surfaces and constrained density functional theory to understand ethylene carbonate reduction on passivated electrode surfaces.

Characterisation of social impacts in LCA. Part 2: implementation in six company case studies

DEFF Research Database (Denmark)

Dreyer, Louise Camilla; Hauschild, Michael Zwicky; Schierbeck, Jens

2010-01-01

, Restrictions of freedom of association and collective bargaining, and Child labour (Dreyer et al, 2009a). These impact categories are considered by the authors to be among the obligatory impact categories in a Social LCA. The characterisation models combine information about the way a company manages its...... or industrial branch or sector) of the company. The resulting indicator score represents the risk that violations take place of the labour right represented by the impact category. Results The social impact characterisation is performed for each of the six case studies using the methodology earlier developed...

Electrochemically deposited hybrid nickel-cobalt hexacyanoferrate nanostructures for electrochemical supercapacitors

International Nuclear Information System (INIS)

Safavi, A.; Kazemi, S.H.; Kazemi, H.

2011-01-01

Highlights: → Nanostructured hybrid nickel-cobalt hexacyanoferrate is used in supercapacitors. → A high capacitance (765 F g -1 ) is obtained at a specific current of 0.2 A g -1 . → Long cycle-life and excellent stability are demonstrated during 1000 cycles. - Abstract: This study describes the use of electrodeposited nanostructured hybrid nickel-cobalt hexacyanoferrate in electrochemical supercapacitors. Herein, various compositions of nickel and cobalt hexacyanoferrates (Ni/CoHCNFe) nanostructures are electrodeposited on an inexpensive stainless steel substrate using cyclic voltammetric (CV) method. The morphology of the electrodeposited nanostructures is studied using scanning electron microscopy, while their electrochemical characterizations are investigated using CV, galvanostatic charge and discharge and electrochemical impedance spectroscopy. The results show that the nanostructures of hybrid metal cyanoferrate, shows a much higher capacitance (765 F g -1 ) than those obtained with just nickel hexacyanoferrate (379 F g -1 ) or cobalt hexacyanoferrate (277 F g -1 ). Electrochemical impedance spectroscopy results confirm the favorable capacitive behavior of the electrodeposited materials. The columbic efficiency is approximately 95% based on the charge and discharge experiments. Long cycle-life and excellent stability of the nanostructured materials are also demonstrated during 1000 cycles.

Electrochemically deposited hybrid nickel-cobalt hexacyanoferrate nanostructures for electrochemical supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Safavi, A., E-mail: safavi@chem.susc.ac.ir [Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Nanotechnology Research Institute, Shiraz University, Shiraz (Iran, Islamic Republic of); Kazemi, S.H., E-mail: habibkazemi@iasbs.ac.ir [Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731 (Iran, Islamic Republic of); Kazemi, H. [Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of)

2011-10-30

Highlights: > Nanostructured hybrid nickel-cobalt hexacyanoferrate is used in supercapacitors. > A high capacitance (765 F g{sup -1}) is obtained at a specific current of 0.2 A g{sup -1}. > Long cycle-life and excellent stability are demonstrated during 1000 cycles. - Abstract: This study describes the use of electrodeposited nanostructured hybrid nickel-cobalt hexacyanoferrate in electrochemical supercapacitors. Herein, various compositions of nickel and cobalt hexacyanoferrates (Ni/CoHCNFe) nanostructures are electrodeposited on an inexpensive stainless steel substrate using cyclic voltammetric (CV) method. The morphology of the electrodeposited nanostructures is studied using scanning electron microscopy, while their electrochemical characterizations are investigated using CV, galvanostatic charge and discharge and electrochemical impedance spectroscopy. The results show that the nanostructures of hybrid metal cyanoferrate, shows a much higher capacitance (765 F g{sup -1}) than those obtained with just nickel hexacyanoferrate (379 F g{sup -1}) or cobalt hexacyanoferrate (277 F g{sup -1}). Electrochemical impedance spectroscopy results confirm the favorable capacitive behavior of the electrodeposited materials. The columbic efficiency is approximately 95% based on the charge and discharge experiments. Long cycle-life and excellent stability of the nanostructured materials are also demonstrated during 1000 cycles.

Characterisation of PV CIS module by artificial neural networks. A comparative study with other methods

International Nuclear Information System (INIS)

Almonacid, F.; Rus, C.; Hontoria, L.; Munoz, F.J.

2010-01-01

The presence of PV modules made with new technologies and materials is increasing in PV market, in special Thin Film Solar Modules (TFSM). They are ready to make a substantial contribution to the world's electricity generation. Although Si wafer-based cells account for the most of increase, technologies of thin film have been those of the major growth in last three years. During 2007 they grew 133%. On the other hand, manufacturers provide ratings for PV modules for conditions referred to as Standard Test Conditions (STC). However, these conditions rarely occur outdoors, so the usefulness and applicability of the indoors characterisation in standard test conditions of PV modules is a controversial issue. Therefore, to carry out a correct photovoltaic engineering, a suitable characterisation of PV module electrical behaviour is necessary. The IDEA Research Group from Jaen University has developed a method based on artificial neural networks (ANNs) to electrical characterisation of PV modules. An ANN was able to generate V-I curves of si-crystalline PV modules for any irradiance and module cell temperature. The results show that the proposed ANN introduces a good accurate prediction for si-crystalline PV modules performance when compared with the measured values. Now, this method is going to be applied for electrical characterisation of PV CIS modules. Finally, a comparative study with other methods, of electrical characterisation, is done. (author)

Electrochemical characterisation of X10CrNi 18-8 steel in artificial plasma

Directory of Open Access Journals (Sweden)

J. Przondziono

2015-01-01

Full Text Available Quality of applied guide wires conditions the course of treatment and its success to a great extent. In order to simulate conditions that can be found in blood vascular system samples were exposed to artificial blood plasma (T = 37 } 1 oC for the time of 8 h. In order to obtain information regarding physical and chemical properties of modified surface of wire made of X10CrNi 18-8 steel, electrochemical impedance spectroscopy (EIS test and tests of chemical composition of the surface layer X-ray photoelectron spectroscopy (XPS were made. On the ground of performed EIS and XPS tests, favourable impact of steam sterilisation process on corrosion resistance of X10CrNi 18-8 steel was observed only for the case when chemical passivation was applied prior to sterilisation.

Cycle aging studies of lithium nickel manganese cobalt oxide-based batteries using electrochemical impedance spectroscopy

NARCIS (Netherlands)

Maheshwari, Arpit; Heck, Michael; Santarelli, Massimo

2018-01-01

The cycle aging of a commercial 18650 lithium-ion battery with graphite anode and lithium nickel manganese cobalt (NMC) oxide-based cathode at defined operating conditions is studied by regular electrochemical characterization, electrochemical impedance spectroscopy (EIS) and post-mortem analysis.

Kinetic mechanism for modeling of electrochemical reactions.

Science.gov (United States)

Cervenka, Petr; Hrdlička, Jiří; Přibyl, Michal; Snita, Dalimil

2012-04-01

We propose a kinetic mechanism of electrochemical interactions. We assume fast formation and recombination of electron donors D- and acceptors A+ on electrode surfaces. These mediators are continuously formed in the electrode matter by thermal fluctuations. The mediators D- and A+, chemically equivalent to the electrode metal, enter electrochemical interactions on the electrode surfaces. Electrochemical dynamics and current-voltage characteristics of a selected electrochemical system are studied. Our results are in good qualitative agreement with those given by the classical Butler-Volmer kinetics. The proposed model can be used to study fast electrochemical processes in microsystems and nanosystems that are often out of the thermal equilibrium. Moreover, the kinetic mechanism operates only with the surface concentrations of chemical reactants and local electric potentials, which facilitates the study of electrochemical systems with indefinable bulk.

Studies of electrochemical interfaces by TOF neutron reflectometry at the IBR-2 reactor

Science.gov (United States)

Petrenko, V. I.; Gapon, I. V.; Rulev, A. A.; Ushakova, E. E.; Kataev, E. Yu; Yashina, L. V.; Itkis, D. M.; Avdeev, M. V.

2018-03-01

The operation performance of electrochemical energy conversion and storage systems such as supercapacitors and batteries depends on the processes occurring at the electrochemical interfaces, where charge separation and chemical reactions occur. Here, we report about the tests of the neutron reflectometry cells specially designed for operando studies of structural changes at the electrochemical interfaces between solid electrodes and liquid electrolytes. The cells are compatible with anhydrous electrolytes with organic solvents, which are employed today in all lithium ion batteries and most supercapacitors. The sensitivity of neutron reflectometry applied at the time-of-flight (TOF) reflectometer at the pulsed reactor IBR-2 is discussed regarding the effect of solid electrolyte interphase (SEI) formation on metal electrode surface.

Electrochemical Analysis of Neurotransmitters

Science.gov (United States)

Bucher, Elizabeth S.; Wightman, R. Mark

2015-07-01

Chemical signaling through the release of neurotransmitters into the extracellular space is the primary means of communication between neurons. More than four decades ago, Ralph Adams and his colleagues realized the utility of electrochemical methods for the study of easily oxidizable neurotransmitters, such as dopamine, norepinephrine, and serotonin and their metabolites. Today, electrochemical techniques are frequently coupled to microelectrodes to enable spatially resolved recordings of rapid neurotransmitter dynamics in a variety of biological preparations spanning from single cells to the intact brain of behaving animals. In this review, we provide a basic overview of the principles underlying constant-potential amperometry and fast-scan cyclic voltammetry, the most commonly employed electrochemical techniques, and the general application of these methods to the study of neurotransmission. We thereafter discuss several recent developments in sensor design and experimental methodology that are challenging the current limitations defining the application of electrochemical methods to neurotransmitter measurements.

Characterisation of bulk solids

Energy Technology Data Exchange (ETDEWEB)

D. McGlinchey [Glasgow Caledonian University, Glasgow (United Kingdom). Centre for Industrial Bulk Solids Handling

2005-07-01

Handling of powders and bulk solids is a critical industrial technology across a broad spectrum of industries, including minerals processing. With contributions from leading authors in their respective fields, this book provides the reader with a sound understanding of the techniques, importance and application of particulate materials characterisation. It covers the fundamental characteristics of individual particles and bulk particulate materials, and includes discussion of a wide range of measurement techniques, and the use of material characteristics in design and industrial practice. Contents: Characterising particle properties; Powder mechanics and rheology; Characterisation for hopper and stockpile design; Fluidization behaviour; Characterisation for pneumatic conveyor design; Explosiblility; 'Designer' particle characteristics; Current industrial practice; and Future trends. 130 ills.

Synthesis and electrochemical study of Pt-based nanoporous materials

International Nuclear Information System (INIS)

Wang Jingpeng; Holt-Hindle, Peter; MacDonald, Duncan; Thomas, Dan F.; Chen Aicheng

2008-01-01

In the present work, a variety of Pt-based bimetallic nanostructured materials including nanoporous Pt, Pt-Ru, Pt-Ir, Pt-Pd and Pt-Pb networks have been directly grown on titanium substrates via a facile hydrothermal method. The as-fabricated electrodes were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and electrochemical methods. The active surface areas of these nanoporous Pt-based alloy catalysts are increased by over 68 (Pt-Pd), 69 (Pt-Ru) and 113 (Pt-Ir) fold compared to a polycrystalline Pt electrode. All these synthesized nanoporous electrodes exhibit superb electrocatalytic performance towards electrochemical oxidation of methanol and formic acid. Among the five nanoporous Pt-based electrodes, the Pt-Ir shows the highest peak current density at +0.50 V, with 68 times of enhancement compared to the polycrystalline Pt for methanol oxidation, and with 86 times of enhancement in formic acid oxidation; whereas the catalytic activity of the nanoporous Pt-Pb electrode outperforms the other materials in formic acid oxidation at the low potential regions, delivering an enhanced current density by 280-fold compared to the polycrystalline Pt at +0.15 V. The new approach described in this study is suitable for synthesizing a wide range of bi-metallic and tri-metallic nanoporous materials, desirable for electrochemical sensor design and potential application in fuel cells

Synthesis and electrochemical study of Pt-based nanoporous materials

Energy Technology Data Exchange (ETDEWEB)

Wang Jingpeng [Department of Chemistry, Lakehead University, Thunder Bay, Ontario P7B 5E1 (Canada); Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Holt-Hindle, Peter; MacDonald, Duncan [Department of Chemistry, Lakehead University, Thunder Bay, Ontario P7B 5E1 (Canada); Thomas, Dan F. [Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Chen Aicheng [Department of Chemistry, Lakehead University, Thunder Bay, Ontario P7B 5E1 (Canada)], E-mail: aicheng.chen@lakeheadu.ca

2008-10-01

In the present work, a variety of Pt-based bimetallic nanostructured materials including nanoporous Pt, Pt-Ru, Pt-Ir, Pt-Pd and Pt-Pb networks have been directly grown on titanium substrates via a facile hydrothermal method. The as-fabricated electrodes were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and electrochemical methods. The active surface areas of these nanoporous Pt-based alloy catalysts are increased by over 68 (Pt-Pd), 69 (Pt-Ru) and 113 (Pt-Ir) fold compared to a polycrystalline Pt electrode. All these synthesized nanoporous electrodes exhibit superb electrocatalytic performance towards electrochemical oxidation of methanol and formic acid. Among the five nanoporous Pt-based electrodes, the Pt-Ir shows the highest peak current density at +0.50 V, with 68 times of enhancement compared to the polycrystalline Pt for methanol oxidation, and with 86 times of enhancement in formic acid oxidation; whereas the catalytic activity of the nanoporous Pt-Pb electrode outperforms the other materials in formic acid oxidation at the low potential regions, delivering an enhanced current density by 280-fold compared to the polycrystalline Pt at +0.15 V. The new approach described in this study is suitable for synthesizing a wide range of bi-metallic and tri-metallic nanoporous materials, desirable for electrochemical sensor design and potential application in fuel cells.0.

Synthesis and electrochemical study of Pt-based nanoporous materials

Energy Technology Data Exchange (ETDEWEB)

Wang, Jingpeng [Department of Chemistry, Lakehead University, Thunder Bay, Ontario P7B 5E1 (Canada); Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Holt-Hindle, Peter; MacDonald, Duncan; Chen, Aicheng [Department of Chemistry, Lakehead University, Thunder Bay, Ontario P7B 5E1 (Canada); Thomas, Dan F. [Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1 (Canada)

2008-10-01

In the present work, a variety of Pt-based bimetallic nanostructured materials including nanoporous Pt, Pt-Ru, Pt-Ir, Pt-Pd and Pt-Pb networks have been directly grown on titanium substrates via a facile hydrothermal method. The as-fabricated electrodes were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and electrochemical methods. The active surface areas of these nanoporous Pt-based alloy catalysts are increased by over 68 (Pt-Pd), 69 (Pt-Ru) and 113 (Pt-Ir) fold compared to a polycrystalline Pt electrode. All these synthesized nanoporous electrodes exhibit superb electrocatalytic performance towards electrochemical oxidation of methanol and formic acid. Among the five nanoporous Pt-based electrodes, the Pt-Ir shows the highest peak current density at +0.50 V, with 68 times of enhancement compared to the polycrystalline Pt for methanol oxidation, and with 86 times of enhancement in formic acid oxidation; whereas the catalytic activity of the nanoporous Pt-Pb electrode outperforms the other materials in formic acid oxidation at the low potential regions, delivering an enhanced current density by 280-fold compared to the polycrystalline Pt at +0.15 V. The new approach described in this study is suitable for synthesizing a wide range of bi-metallic and tri-metallic nanoporous materials, desirable for electrochemical sensor design and potential application in fuel cells. (author)

Electrochemical applications of CVD diamond

International Nuclear Information System (INIS)

Pastor-Moreno, Gustavo

2002-01-01

Diamond technology has claimed an important role in industry since non-expensive methods of synthesis such as chemical vapour deposition allow to elaborate cheap polycrystalline diamond. This fact has increased the interest in the scientific community due to the outstanding properties of diamond. Since Pleskov published in 1987 the first paper in electrochemistry, many researchers around the world have studied different aspects of diamond electrochemistry such as reactivity, electrical structure, etc. As part of this worldwide interest these studies reveal new information about diamond electrodes. These studies report investigation of diamond electrodes characterized using structural techniques like scanning electrode microscopy and Raman spectroscopy. A new electrochemical theory based on surface states is presented that explains the metal and the semiconductor behaviour in terms of the doping level of the diamond electrode. In an effort to characterise the properties of diamond electrodes the band edges for hydrogen and oxygen terminated surface are located in organic solvent, hence avoiding possible interference that are present in aqueous solution. The determination of the band edges is performed by Mott-Schottky studies. These allow the calculation of the flat band potential and therefore the band edges. Additional cyclic voltammetric studies are presented for both types of surface termination. Mott-Schottky data and cyclic voltammograms are compared and explained in terms of the band edge localisation. Non-degenerately p-type semiconductor behaviour is presented for hydrogen terminated boron doped diamond. Graphitic surface states on oxidised surface boron doped diamond are responsible for the electrochemistry of redox couples that posses similar energy. Using the simple redox couple 1,4-benzoquinone effect of surface termination on the chemical behaviour of diamond is presented. Hydrogen sublayers in diamond electrodes seem to play an important role for the

Simultaneous electrochemical-electron spin resonance studies of carotenoid cation radicals and dications

International Nuclear Information System (INIS)

Khaled, M.; Hadjipetrou, A.; Xinhai Chen; Kispert, L.

1989-01-01

Carotenoids are present in the chloroplasts of photosynthetic green plants and serve as photoprotect devices and antenna pigments, and active role in the photosynthetic electron-transport chain with the carotenoid cation radical as an integral part of the electron-transfer process. The research reported herein has confirmed that carotenoid cation radicals have a lifetime that is sensitive to solvent, being longest in CH 2 Cl 2 and are best prepared electrochemically. Semiempirical AM1 and INDO calculations of the trans and cis isomers of β-carotene, canthaxanthin and β-apo-8'-carotenal cation radicals predicted the unresolved EPR line whose linewidth varies to a measurable degree with carotenoid, which subsequent experimental observations affirmed. Simultaneous electrochemical - electron spin resonance studies of carotenoid cation radicals and dications have shown the radicals detected by EPR are formed by the one electron oxidation of the carotenoid, that dimers are not formed upon decay of the radical cations and an estimate of the rate of comproportionation as a function of carotenoid can be given. The formal rate constant K' for heterogenous electron transfer rate at the electrode surface has been deduced from rotating disc experiments. Upon deuteration, and in the presence of excess β-carotene, the half-life for decay of the carotenoid radical cation increased an order of magnitude due to the reaction between diffusion carotenoid dications and carotenoids to form additional radical cations. The carotenoid diffusion coefficients deduced by chronocoulometry substantiates this measurement. The produces formed upon electrochemical studies are being studied by HPLC and the isomers formed thermally are being separated. Additional radical reactions are currently being studied by EPR and electrochemical methods

Characterisation: Challenges and Opportunities - A UK Perspective

International Nuclear Information System (INIS)

Emptage, Matthew; Loudon, David; Mcleod, Richard; Milburn, Helen

2016-01-01

Characterisation plays a very important role in the nuclear industry supporting: the development and implementation of decommissioning strategies/plans (and the optimisation of associated costs through reduction in technical risks); regulatory compliance demonstration; waste prevention/minimisation; evaluation and optimisation of worker radiation doses; and maintaining public confidence. Recognising these important drivers, the UK regulators are working with the UK Nuclear Decommissioning Authority (NDA) to undertake a review of characterisation practice in the UK nuclear (decommissioning) industry. The objective of the characterisation review is to understand the current characterisation challenges and to determine strategic and tactical opportunities (including sharing of standards and guidance, capabilities, learning from experience, good practice, research and development, training, quality assurance) to optimise characterisation practice. The work is being undertaken through review of nuclear operator's characterisation practice, with input from the NDA, the UK regulators, nuclear operators and representatives from the supply chain, and through consideration of good practice case studies. To support this, a catalogue of relevant national/international guidance documents is also be compiled. Finally a workshop with representatives from all parties has taken place to consider the findings and establish a common understanding of challenges and opportunities and to start to consider how they can be addressed. The review is establishing a collective (UK regulator's, NDA; nuclear operator's and supply chain) understanding of opportunities to improve characterisation practice in the UK. The characterisation review process is described and early results are presented and discussed. Subsequent work in 2016 will be required to prioritise the opportunities and to build a consensus to facilitate development and implementation of an improvement plan. The aim

Shadow corrosion phenomenon. An out-of-pile study on electrochemical effects

Energy Technology Data Exchange (ETDEWEB)

Weber, Nadine

2017-04-28

The focus of the present thesis was the study of the enhanced corrosion phenomenon named ''Shadow Corrosion''. Within the context of researching based on the corrosion mechanism as well as the influencing parameters and driving forces, which cause or even intensify the corrosion, a variety of electrochemical characterization and surface analysis techniques were used. The first part of this thesis gives a short introduction with the definition of the term Shadow Corrosion and of the specific type called ''Enhanced Spacer Shadow Corrosion'' (ESSC). This is followed by a description of the involved materials being Zircaloy and Inconel 718. Chapter 2 introduces the background knowledge including fundamentals about environ-mental conditions under which Shadow Corrosion occurs as well as the oxidation behavior of Zircaloy and Inconel 718. Furthermore, the state of the art about the Shadow Corrosion mechanism is presented and a description of the influencing effects on the enhanced corrosion phenomenon, like galvanic corrosion, water radiolysis, and photo-effect, is given. Further information and parameters on the part of AREVA GmbH concerning water impurities and a used coating layer on Inconel 718 are listed, which are of interest for the issue concerning the phenomenon Shadow Corrosion. The last part of this chapter contains the experimental conditions and parameters for the laboratory experiments with focus on water chemistry, specimen geometry, and UV-light exposure for photoexcitation and water radiolysis. Three different working hypotheses of this thesis are described in chapter 3. One hypothesis regarding the Shadow Corrosion Phenomenon is based on a galvanic corrosion mechanism between Zircaloy and Inconel 718. In addition, it is supposed that the galvanic corrosion could be influenced by the deposition of silver on Zircaloy and Inconel 718 in the form of an increased galvanic current. A further assumption is that the

Shadow corrosion phenomenon. An out-of-pile study on electrochemical effects

International Nuclear Information System (INIS)

Weber, Nadine

2017-01-01

The focus of the present thesis was the study of the enhanced corrosion phenomenon named ''Shadow Corrosion''. Within the context of researching based on the corrosion mechanism as well as the influencing parameters and driving forces, which cause or even intensify the corrosion, a variety of electrochemical characterization and surface analysis techniques were used. The first part of this thesis gives a short introduction with the definition of the term Shadow Corrosion and of the specific type called ''Enhanced Spacer Shadow Corrosion'' (ESSC). This is followed by a description of the involved materials being Zircaloy and Inconel 718. Chapter 2 introduces the background knowledge including fundamentals about environ-mental conditions under which Shadow Corrosion occurs as well as the oxidation behavior of Zircaloy and Inconel 718. Furthermore, the state of the art about the Shadow Corrosion mechanism is presented and a description of the influencing effects on the enhanced corrosion phenomenon, like galvanic corrosion, water radiolysis, and photo-effect, is given. Further information and parameters on the part of AREVA GmbH concerning water impurities and a used coating layer on Inconel 718 are listed, which are of interest for the issue concerning the phenomenon Shadow Corrosion. The last part of this chapter contains the experimental conditions and parameters for the laboratory experiments with focus on water chemistry, specimen geometry, and UV-light exposure for photoexcitation and water radiolysis. Three different working hypotheses of this thesis are described in chapter 3. One hypothesis regarding the Shadow Corrosion Phenomenon is based on a galvanic corrosion mechanism between Zircaloy and Inconel 718. In addition, it is supposed that the galvanic corrosion could be influenced by the deposition of silver on Zircaloy and Inconel 718 in the form of an increased galvanic current. A further assumption is that the galvanic current could be decreased by a Cr

Surface characterisation and electrochemical behaviour of porous titanium dioxide coated 316L stainless steel for orthopaedic applications

International Nuclear Information System (INIS)

Nagarajan, S.; Rajendran, N.

2009-01-01

Porous titanium dioxide was coated on surgical grade 316L stainless steel (SS) and its role on the corrosion protection and enhanced biocompatibility of the materials was studied. X-ray diffraction analysis (XRD), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) were carried out to characterise the surface morphology and also to understand the structure of the as synthesised coating on the substrates. The corrosion behaviour of titanium dioxide coated samples in simulated body fluid was evaluated using polarisation and impedance spectroscopy studies. The results reveal that the titanium dioxide coated 316L SS exhibit a higher corrosion resistance than the uncoated 316L SS. The titanium dioxide coated surface is porous, uniform and also it acts as a barrier layer to metallic substrate and the porous titanium dioxide coating induces the formation of hydroxyapatite layer on the metal surface.

Formation of a cerium conversion coating on magnesium alloy using ascorbic acid as additive. Characterisation and anticorrosive properties of the formed films

OpenAIRE

A.P. Loperena; I.L. Lehr; S.B. Saidman.

2016-01-01

Cerium-based conversion coatings were formed on AZ91D magnesium alloy by immersion of the substrate in solutions containing Ce(NO3)3, H2O2 and ascorbic acid (HAsc). The characterisation of the films was performed by electrochemical and surface analysis techniques such as SEM, EDS, X-ray diffraction and X-ray photoelectron spectroscopy (XPS). The degree of corrosion protection achieved was evaluated in simulated physiological solution by the open circuit potential monitoring, polarisation tech...

Study of electrochemical phosphate conversion coating of metallic surfaces

International Nuclear Information System (INIS)

Gougelin, Patrick

1985-01-01

After an overview on phosphate conversion coating processes, on models of iron electrochemical dissolution, on the passivation phenomenon, and on the phosphate conversion coating treatment, this research thesis reports a detailed study of this last process. The author presents the experimental method, reports the study of this process and of passivation under constant polarization. He reports the use of various techniques and conditions: chrono-amperometry, chrono-potentiometry, cyclic volt-amperometry

Studies on mass transfer in electrochemical systems

Energy Technology Data Exchange (ETDEWEB)

Sundstroem, L.G.

1997-10-01

The first part is of an introductory nature. It contains a description of the methods used, a discussion of the physics of electrochemical cells with a liquid electrolyte, and a summary of the different studies made, including both those which have been reported in papers, and those which have not. Contributions with novel aspects include (* a derivation of the electro-neutrality condition from Maxwell`s equations of electrodynamics, and **) an argument in favour of the use of mass-averaged velocity in ion transport expressions. The second part focuses on specific cases. It consists of seven research papers which give a more detailed presentation of the main studies 40 refs, 6 figs

Electrochemical sensors applied to pollution monitoring: Measurement error and gas ratio bias - A volcano plume case study

Science.gov (United States)

Roberts, T. J.; Saffell, J. R.; Oppenheimer, C.; Lurton, T.

2014-06-01

There is an increasing scientific interest in the use of miniature electrochemical sensors to detect and quantify atmospheric trace gases. This has led to the development of ‘Multi-Gas' systems applied to measurements of both volcanic gas emissions, and urban air pollution. However, such measurements are subject to uncertainties introduced by sensor response time, a critical issue that has received limited attention to date. Here, a detailed analysis of output from an electrochemical SO2 sensor and two H2S sensors (contrasting in their time responses and cross-sensitivities) demonstrates how instrument errors arise under the conditions of rapidly fluctuating (by dilution) gas abundances, leading to scatter and importantly bias in the reported gas ratios. In a case study at Miyakejima volcano (Japan), electrochemical sensors were deployed at both the crater-rim and downwind locations, thereby exposed to rapidly fluctuating and smoothly varying plume gas concentrations, respectively. Discrepancies in the H2S/SO2 gas mixing ratios derived from these measurements are attributed to the sensors' differing time responses to SO2 and H2S under fluctuating plume conditions, with errors magnified by the need to correct for SO2 interference in the H2S readings. Development of a sensor response model that reproduces sensor t90 behaviour (the time required to reach 90% of the final signal following a step change in gas abundance) during calibration enabled this measurement error to be simulated numerically. The sensor response times were characterised as SO2 sensor (t90 ~ 13 s), H2S sensor without interference (t90 ~ 11 s), and H2S sensor with interference (t90 ~ 20 s to H2S and ~ 32 s to SO2). We show that a method involving data integration between periods of episodic plume exposure identifiable in the sensor output yields a less biased H2S/SO2 ratio estimate than that derived from standard analysis approaches. For the Miyakejima crater-rim dataset this method yields highly

Electrochemical deposition of TiB2 in high temperature molten salts

International Nuclear Information System (INIS)

Fastner, U.; Steck, T.; Pascual, A.; Fafilek, G.; Nauer, G.E.

2008-01-01

The electrochemical deposition of TiB 2 out of a NaCl-KCl-NaF-KBF 4 -K 2 TiF 6 electrolyte at 600 deg. C was tested on steel and molybdenum substrates using various current programs. The characterisation of the deposited layers has been carried out by X-ray diffraction methods, scanning electron microscopy and microhardness measurements. The pulse sequences and the current densities used influence in a significant way the homogeneity of the layers deposited, the crystal size, the texture and other physical properties like electrical and thermal conductivity. The microhardness range was up to 2900 HV, smooth and dense layers were prepared at a pulse frequency of 100 Hz

Spectro-electrochemical Studies of Europium and Uranium Ions in LiCl-KCl Eutectic

Energy Technology Data Exchange (ETDEWEB)

Bae, Sang Eun; Park, Yong Joon; Cho, Young Hwan; Song, Kyu Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2010-05-15

Pyrochemical processing of nuclear fuels using a molten salt as a solvent is regarded as one of the promising options for future spent nuclear fuel management. Molten salts are known as suitable media for electrorefining and electrowinning of metal in the Pyrochemical process. There are complicated chemical and electrochemical reactions in the molten salt of the Pyrochemical process. In order to reach a better understanding and control of these metal deposition processes, accurate knowledge of the reaction mechanism is essential. Spectroscopic methods, such as fluorescence and UV-VIS spectroscopy, are considered to be one of powerful tools to investigate the chemical elements and its oxidation state. In this work, the spectroscopic studies have been performed under the electrochemical control to investigate the reaction mechanisms in the molten salt at high temperature during the electrochemical reactions

Spectro-electrochemical Studies of Europium and Uranium Ions in LiCl-KCl Eutectic

International Nuclear Information System (INIS)

Bae, Sang Eun; Park, Yong Joon; Cho, Young Hwan; Song, Kyu Seok

2010-01-01

Pyrochemical processing of nuclear fuels using a molten salt as a solvent is regarded as one of the promising options for future spent nuclear fuel management. Molten salts are known as suitable media for electrorefining and electrowinning of metal in the Pyrochemical process. There are complicated chemical and electrochemical reactions in the molten salt of the Pyrochemical process. In order to reach a better understanding and control of these metal deposition processes, accurate knowledge of the reaction mechanism is essential. Spectroscopic methods, such as fluorescence and UV-VIS spectroscopy, are considered to be one of powerful tools to investigate the chemical elements and its oxidation state. In this work, the spectroscopic studies have been performed under the electrochemical control to investigate the reaction mechanisms in the molten salt at high temperature during the electrochemical reactions

Permeability, strength and electrochemical studies on ceramic multilayers for solid-state electrochemical cells

DEFF Research Database (Denmark)

Andersen, Kjeld Bøhm; Charlas, Benoit; Stamate, Eugen

2017-01-01

An electrochemical reactor can be used to purify flue gasses. Such a reactor can be a multilayer structure consisting of alternating layers of porous electrodes and electrolytes (a porous cell stack). In this work optimization of such a unit has been done by changing the pore former composition...

Effect of Amine Adlayer on Electrochemical Uric Acid Sensor Conducted on Electrochemically Reduced Graphene Oxide

Energy Technology Data Exchange (ETDEWEB)

Park, Sumi; Kim, Kyuwon [Incheon National University, Incheon (Korea, Republic of)

2016-03-15

The electrochemical biosensing efficiency of uric acid (UA) detection on an electrochemically reduced graphene oxide (ERGO)-decorated electrode surface was studied by using various amine linkers used to immobilize ERGO. The amine linkers aminoethylphenyldiazonium , 2,2'-(ethylenedioxy)bis(ethylamine), 3-aminopro-pyltriethoxysilane, and polyethyleneimine were coated on indium-tin-oxide electrode surfaces through chemical or electrochemical deposition methods. ERGO-decorated surfaces were prepared by the electrochemical reduction of graphene oxide (GO), which was immobilized on the amine-coated electrode surfaces through the electrostatic interaction between GO and the ammonium ion of the linker on the surface. We monitored the sensing results of electrochemical UA detection with differential pulse voltammetry. The ERGO-modified surface presented electrocatalytic oxidation of UA and ascorbic acid. Among the different amines tested, 3-aminopropyltriethoxysilane provided the best biosensing performance in terms of sensitivity and reproducibility.

Effect of Amine Adlayer on Electrochemical Uric Acid Sensor Conducted on Electrochemically Reduced Graphene Oxide

International Nuclear Information System (INIS)

Park, Sumi; Kim, Kyuwon

2016-01-01

The electrochemical biosensing efficiency of uric acid (UA) detection on an electrochemically reduced graphene oxide (ERGO)-decorated electrode surface was studied by using various amine linkers used to immobilize ERGO. The amine linkers aminoethylphenyldiazonium , 2,2'-(ethylenedioxy)bis(ethylamine), 3-aminopro-pyltriethoxysilane, and polyethyleneimine were coated on indium-tin-oxide electrode surfaces through chemical or electrochemical deposition methods. ERGO-decorated surfaces were prepared by the electrochemical reduction of graphene oxide (GO), which was immobilized on the amine-coated electrode surfaces through the electrostatic interaction between GO and the ammonium ion of the linker on the surface. We monitored the sensing results of electrochemical UA detection with differential pulse voltammetry. The ERGO-modified surface presented electrocatalytic oxidation of UA and ascorbic acid. Among the different amines tested, 3-aminopropyltriethoxysilane provided the best biosensing performance in terms of sensitivity and reproducibility.

Characterisation of humic material for inter-laboratory comparison

International Nuclear Information System (INIS)

Peachy, D.; Bradley, A.D.; Davis, A.E.; Stuart, M.E.; Tait, B.A.R.; Vickers, B.P.; Williams, G.M.

1988-01-01

The characterisation and interlaboratory comparison of common humic materials by members of the European Commission's COCO group (set up to study complexes and colloids), forms part of a study of the effects of natural organic compounds in groundwater on the complexation and mobility of radionuclides. Three samples have been characterised: a sodium salt and a protonated form of the commercially available humic acid from Aldrich Chemicals; and a protonated humic acid from the Gorleben research site in Germany. Characterisation undertaken by BGS includes moisture content, elemental analysis, metal content, functional group analysis, infra-red spectroscopy, ultra-violet absorbance (E 4 /E 6 ratios), and ultra-filtration. (author)

Electrokinetic and electrochemical corrosion studies related to crud formation

International Nuclear Information System (INIS)

Scenini, Fabio; Palumbo, Gaetano; Stevens, Nicholas; Cook, Tony; Banks, Andrew

2012-09-01

A potentially important mechanism for the flow-induced deposition of CRUD from pressurised high temperature primary water is the effect of 'streaming potentials' that develop across the electrochemical double layer of a metallic surface as a result of fluid flow across a pressure gradient or orifice. Thus, under such conditions, streaming currents develop normal to a surface and may result in preferential oxidation, for example of dissolved ferrous to ferric ions with their subsequent deposition as an oxide. The approach presented in this paper was to consider the electrokinetic problem is to firstly consider the magnitude of currents that can be developed under a given set of flow/mass transport conditions and, secondly, to consider the way in which these relatively small currents might give rise to oxide deposition. Electrochemical measurements on 304L samples were carried out over a range of temperatures in hydrogenated, alkaline water. The test conditions were chosen in order to simulate PWR primary water conditions. Furthermore, in order to facilitate the electrochemical studies, the ferrous ion concentration in the solution was also enhanced by the presence of a mild steel plate left in the autoclave to corrode. By employing the cyclic voltammetry technique interpreted using the Randles-Sevcik equation it was possible to calculate the concentration of ferrous ions and their diffusion coefficient. A miniature flow cell was designed for the purpose of creating regions of accelerated flow with consequent formation of anodic and cathodic regions so as to be able to measure the streaming currents. A study was carried out in order to better understand the potential which is associated with the streaming potential as function of the velocity and temperature at fixed pH. (authors)

Electrochemical studies on plutonium in molten salts

International Nuclear Information System (INIS)

Bourges, G.; Lambertin, D.; Rochefort, S.; Delpech, S.; Picard, G.

2007-01-01

Electrochemical studies on plutonium have been supporting the development of pyrochemical processes involving plutonium at CEA. The electrochemical properties of plutonium have been studied in molten salts - ternary eutectic mixture NaCl-KCl-BaCl 2 , equimolar mixture NaCl-KCl and pure CaCl 2 - and in liquid gallium at 1073 K. The formal, or apparent, standard potential of Pu(III)/Pu redox couple in eutectic mixture of NaCl-KCl-BaCl 2 at 1073 K determined by potentiometry is equal to -2.56 V (versus Cl 2 , 1 atm/Cl - reference electrode). In NaCl-KCl eutectic mixture and in pure CaCl 2 the formal standard potentials deduced from cyclic voltammetry are respectively -2.54 V and -2.51 V. These potentials led to the calculation of the activity coefficients of Pu(III) in the molten salts. Chronoamperometry on plutonium in liquid gallium using molten chlorides - CaCl 2 and equimolar NaCl/KCl - led to the determination of the activity coefficient of Pu in liquid Ga, log γ = -7.3. This new data is a key parameter to assess the thermodynamic feasibility of a process using gallium as solvent metal. By comparing gallium with other solvent metals - cadmium, bismuth, aluminum - gallium appears to be, with aluminum, more favorable for the selectivity of the separation at 1073 K of plutonium from cerium. In fact, compared with a solid tungsten electrode, none of these solvent liquid metals is a real asset for the selectivity of the separation. The role of a solvent liquid metal is mainly to trap the elements

Technological study of electrochemical uranium fuel reprocessing in fused chloride bath

International Nuclear Information System (INIS)

Fernandes, Damaris

2002-01-01

This study is applied to metallic fuels recycling, concerning advanced reactor concept, which was proposed and tested in LMR type reactors. Conditions for electrochemical non-irradiated uranium fuel reprocessing in fused chloride bath in laboratory scale were established. Experimental procedures and parameters for dehydration treatment of LiCl-KCl eutectic mixture and for electrochemical study of U 3+ /U system in LiCl-KCl were developed and optimized. In the voltammetric studies many working electrodes were tested. As auxiliary electrodes, graphite and stainless steels crucibles were verified, with no significant impurities inclusions in the system. Ag/AgCl in Al 2 O 3 with 1 w% in AgCl were used as reference electrode. The experimental set up developed for electrolyte treatment as well as for the study of the system U 3+ /U in LiCl-KCl showed to be adequate and efficient. Thermogravimetric Techniques, Scanning Electron Microscopy with Energy Dispersive X-Ray Spectrometry and cyclic voltametry showed an efficient dehydration method by using HCl gas and than argon flux for 12 h. Scanning Electron Microscopy, with Energy Dispersive X-Ray Spectrometry and Inductively Coupled Plasma Emission Spectrometry and DC Arc Emission Spectrometry detected the presence of uranium in the cadmium phase. X-ray Diffraction and also Inductively Coupled Plasma Emission Spectrometry and DC Arc Emission Spectrometry were used for uranium detection in the salt phase. The obtained results for the system U 3+ /U in LiCl-KCl showed the viability of the electrochemical reprocessing process based on the IFR advanced fuel cycle. (author)

Electrochemical biosensors

CERN Document Server

Cosnier, Serge

2015-01-01

"This is an excellent book on modern electrochemical biosensors, edited by Professor Cosnier and written by leading international experts. It covers state-of-the-art topics of this important field in a clear and timely manner."-Prof. Joseph Wang, UC San Diego, USA 　"This book covers, in 13 well-illustrated chapters, the potential of electrochemical methods intimately combined with a biological component for the assay of various analytes of biological and environmental interest. Particular attention is devoted to the description of electrochemical microtools in close contact with a biological cell for exocytosis monitoring and to the use of nanomaterials in the electrochemical biosensor architecture for signal improvement. Interestingly, one chapter describes the concept and design of self-powered biosensors derived from biofuel cells. Each topic is reviewed by experts very active in the field. This timely book is well suited for providing a good overview of current research trends devoted to electrochemical...

Comparative DEMS study on the electrochemical oxidation of carbon blacks

DEFF Research Database (Denmark)

Ashton, Sean James; Arenz, Matthias

2012-01-01

Publication year: 2012 Source:Journal of Power Sources, Volume 217 Sean J. Ashton, Matthias Arenz The intention of the study presented here is to compare the electrochemical oxidation tendencies of a pristine Ketjen Black EC300 high surface area (HSA) carbon black, and four graphitised counterparts...... heat-treated between 2100 and 3200 °C, such as those typically used as corrosion resistant carbon (CRC) supports for polymer electrolyte membrane fuel cell (PEMFC) catalysts. A methodology combining cyclic voltammetry (CV) and differential electrochemical mass spectrometry (DEMS) is used, which allows......; however, CRC samples graphitised =2800 °C did not exhibit this same behaviour. Highlights ¿ We quantitatively determine electrooxidation of carbon support materials. ¿ We can distinguish between the total and partial electrooxidation. ¿ Non or mildly heat treated carbon forms passivating layer. ¿ Heat...

Development and Electrochemical Investigations of an EIS- (Electrolyte-Insulator-Semiconductor based Biosensor for Cyanide Detection

Directory of Open Access Journals (Sweden)

Michael J. Schöning

2007-08-01

Full Text Available A cyanide biosensor based on a pH-sensitive p-doped electrolyte-insulator-semiconductor (EIS structure with an immobilised enzyme (cyanidase is realised at thelaboratory scale. The immobilisation of the cyanidase is performed in two distinct steps:first, the covalent coupling of cyanidase to an N-hydroxysuccinimide- (NHS activatedSepharoseTM gel and then, the physical entrapment of NHS-activated SepharoseTM with theimmobilised cyanidase in a dialysis membrane onto the EIS structure. The immobilisationof the cyanidase to the NHS-activated SepharoseTM is studied by means of gelelectrophoresis measurements and investigations using an ammonia- (NH3 selectiveelectrode. For the electrochemical characterisation of the cyanide biosensor,capacitance/voltage and constant capacitance measurements, respectively, have beencarried out. A differential measurement procedure is presented to evaluate the cyanideconcentration-dependent biosensor signals.

Evaluation of chemically modified Ti–5Mo–3Fe alloy surface: Electrochemical aspects and in vitro bioactivity on MG63 cells

Energy Technology Data Exchange (ETDEWEB)

Kumar, A. Madhan [Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Sudhagar, P. [Energy Materials Laboratory, WCU Program Department of Energy Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Ramakrishna, Suresh [Graduate School of Biomedical Science and Engineering/College of Medicine, Hanyang University, Sungdong-gu, Seoul (Korea, Republic of); Kang, Yong Soo [Energy Materials Laboratory, WCU Program Department of Energy Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Hyongbum [Graduate School of Biomedical Science and Engineering/College of Medicine, Hanyang University, Sungdong-gu, Seoul (Korea, Republic of); Gasem, Zuhair M. [Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Rajendran, N., E-mail: nrajendran@annauniv.edu [Department of Chemistry, Anna University, Chennai (India)

2014-07-01

Ti–5Mo–3Fe (TMF) alloy is a newly developed β-titanium alloy with low modulus, and it has been deemed as suitable material for dental or orthopaedic implant. The aim of the present study is to evaluate the effect of alkali and hydrogen peroxide treatment on the corrosion and biological performance of TMF surface. The phases, morphology with chemical composition and topography of the treated surface were examined by X-ray diffraction, scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDAX) analysis and atomic force microscopy (AFM), respectively. Micro hardness of treated substrates was measured using Vicker's micro hardness method. The electrochemical studies were carried out using potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) measurements. In order to describe the bio-activity, contact angle measurements, in vitro characterisation and cell culture studies were performed for treated TMF surfaces in simulated body fluid (SBF) and MG63 cells. All these observations showed that the NaOH treatment is the most appropriate method for TMF alloy which exhibited superior biocompatibility and enhanced corrosion protection performance due to their hydrophilic, smooth, compact porous surface morphology than that of other substrates.

Optimization of the use of carbon paste electrodes (CPE for electrochemical study of the chalcopyrite

Directory of Open Access Journals (Sweden)

Daniela G. Horta

2009-01-01

Full Text Available The use of carbon paste electrodes (CPE of mineral sulfides can be useful for electrochemical studies to overcome problems by using massive ones. Using CPE-chalcopyrite some variables were electrochemically evaluated. These variables were: (i the atmosphere of preparation (air or argon of CPE and elapsed time till its use; (ii scan rate for voltammetric measurements and (iii chalcopyrite concentration in the CPE. Based on cyclic voltammetry, open-circuit potential and electrochemical impedance results the recommendations are: oxygen-free atmosphere to prepare and kept the CPE until around two ours, scan rates from 10 to 40 mV s-1, and chalcopyrite concentrations > 20%.

Electrochemical Study of Bromide in the Presence of 1,3-Indandione. Application to the Electrochemical Synthesis of Bromo Derivatives of 1,3-Indandione

Directory of Open Access Journals (Sweden)

N. Akaberi

2001-06-01

Full Text Available The electrochemical oxidation of bromide in the presence of 1,3-indandione (1 in water/acetic acid and methanol/acetic acid mixtures has been studied by cyclic voltammetry and controlled-potential coulometry. The results indicate the participation of 1,3-indandione in the bromination reaction. On the basis of the electroanalytical and preparative results a reaction mechanism including electron transfer, chemical reaction and regeneration of bromide was discussed. The electrochemical synthesis of bromo derivatives of 1,3-indandione (2-3 has been successfully performed at constant current, in an undivided cell, in good yield and purity.

ELECTROCHEMICAL STUDIES OF CARBON STEEL CORROSION IN HANFORD DOUBLE SHELL TANK (DST) WASTE

Energy Technology Data Exchange (ETDEWEB)

DUNCAN, J.B.; WINDISCH, C.F.

2006-10-13

This paper reports on the electrochemical scans for the supernatant of Hanford double-shell tank (DST) 241-SY-102 and the electrochemical scans for the bottom saltcake layer for Hanford DST 241-AZ-102. It further reports on the development of electrochemical test cells adapted to both sample volume and hot cell constraints.

Characterisation of COPD heterogeneity in the ECLIPSE cohort

DEFF Research Database (Denmark)

Agusti, Alvar; Calverley, Peter M A; Celli, Bartolome

2010-01-01

Chronic obstructive pulmonary disease (COPD) is a complex condition with pulmonary and extra-pulmonary manifestations. This study describes the heterogeneity of COPD in a large and well characterised and controlled COPD cohort (ECLIPSE).......Chronic obstructive pulmonary disease (COPD) is a complex condition with pulmonary and extra-pulmonary manifestations. This study describes the heterogeneity of COPD in a large and well characterised and controlled COPD cohort (ECLIPSE)....

Electrochemical energy generation

International Nuclear Information System (INIS)

Kreysa, G.; Juettner, K.

1993-01-01

The proceedings encompass 40 conference papers belonging to the following subject areas: Baseline and review papers; electrochemical fuel cells; batteries: Primary and secondary cells; electrochemical, regenerative systems for energy conversion; electrochemical hydrogen generation; electrochemistry for nuclear power plant; electrochemistry for spent nuclear fuel reprocessing; energy efficiency in electrochemical processes. There is an annex listing the authors and titles of the poster session, and compacts of the posters can be obtained from the office of the Gesellschaft Deutscher Chemiker, Abteilung Tagungen. (MM) [de

Best Practice on facility characterisation from a material and waste end-state perspective. Radiological characterisation in a waste and materials end-state perspective - International Characterisation Survey Aiming to Understand Good Practice

International Nuclear Information System (INIS)

Larsson, Arne; Weber, Inge; Emptage, Matthew; )

2016-01-01

Full text of publication follows: The Task Group on Radiological Characterisation and Decommissioning within the Nuclear Energy Agency (NEA) Working Party on Decommissioning was established to identify and present Best Practice in radiological characterisation at different stages of decommissioning as well as areas that could or should be developed further by international cooperation and coordination. The first phase of the project was focusing on general aspects of strategies for radiological characterisation in decommissioning of nuclear facilities. The second phase of the project focus on strategies for optimising radiological characterisation in a waste and materials end-state perspective, building on previous task group findings. One of the activities within the second phase has been to conduct a survey with the main objective to identify Best Practice. The survey was in the form of a questionnaire in two versions, one for regulators and one for owners/implementers. Sections of the questionnaire to gather views on Best Practice: - Initiation of a characterisation program; - Planning and preparation; - Implementation (i.e. conducting the characterisation measurements and samplings); - Data assessment phase (evaluation of the results); - Quality assurance. A section on the national legislation in the regulator version and a case study section in the owner version complement the questionnaire in order to get an overview of the regulatory frameworks and also practical experiences. The extensive questionnaire was distributed to a wide audience of recognised experts throughout the member states. 53 responses were received from in total 12 countries. Most responses were from Europe but also Asia and North America were represented. The preliminary conclusions are: - There is a solid experience in radiological characterisation among regulators as well as owners/implementers; - Responses demonstrates to large extent a common view of regulators and owners

Physico-chemical characterisation of Indian biomass ashes

Energy Technology Data Exchange (ETDEWEB)

K. Umamaheswaran; Vidya S. Batra [Energy and Resources Institute (TERI), New Delhi (India)

2008-05-15

India stands fourth in biomass utilisation for various purposes like domestic, commercial and industrial applications. While extensive studies have been made for coal ash characterisation and utilisation, studies on characterisation of biomass ash and its utilisation has not been addressed. In this paper, biomass ash from five sources i.e. rice husk, bagasse, groundnut shell, cashewnut shell, and arecanut shell have been characterised. Chemical composition analysis, particle size analysis, thermal analysis, and microstructure analysis were carried out. Results show that in all ashes silica is the major compound with particle size ranging from 15 to 30 {mu}m and having irregular shape. Ash powders originating from cashewnut shell, arecanut shell and groundnut shell also have compounds of calcium, magnesium and potassium. Bagasse and cashewnut shell ashes have high LOI due to presence of unburnt carbon, P{sub 2}O{sub 5} and other volatiles. 16 refs., 22 figs., 3 tabs.

Technetium electrodeposition from aqueous formate solutions at graphite electrode: electrochemical study

International Nuclear Information System (INIS)

Maslennikov, A.; Peretroukhine, V.; Masson, M.; Lecomte, M.

1999-01-01

Recovery of technetium from aqueous formate buffer solutions of ionic strength μ = 1.0 was studied in the pH interval from 1.6 to 7.5 at graphite cathode in an electrolytic cell with separated compartments was studied, using cyclic voltammetry (CV) and inverse stripping voltammetry (ISV) techniques. It has been shown that Tc electrodeposition process becomes possible at the potentials of graphite cathode E cath. 1/2 = -0.72±0.02 V/SCE and was pH independent in the interval pH = 3.46-7.32. Mechanism of electrodeposition, including Tc(VII)/Tc(IV) reduction in the solution followed by Tc(IV) hydrolysis at the electrode surface with formation of hydrated Tc oxide cathodic deposit has been proposed. The further precision of the Tc(VII) electrochemical reduction mechanism in formate buffer media and optimization of the electrodeposition process seems to be possible using additional analytical facilities except electrochemical methods. (orig.)

An electrochemical study of U(VI) and Cr(VI) in molten borates

International Nuclear Information System (INIS)

Brigaudeau, M.; Gregori de Pinochet, I. de

1977-01-01

The electrochemical reduction of U(VI) and Cr(VI), in molten Na 2 B 4 O 7 at 800 deg C was studied by means of linear sweep voltammetry, and chronopotentiometry. The reduction of U(VI) to U(V) proceeded reversibly at a platinum electrode. The diffusion coefficient for the U(VI) species at 800 deg C was 4.10 -7 cm 2 .s -1 . The activation energy of diffusion was (34,8 +- 0,8) kcal. mole -1 . Electrochemical studies of Cr(VI) at 800 0 C reveal a two-step reduction process at a platinum electrode. Only the voltammogram for the first step charge transfer process was studied. Analysis indicated that Cr(VI) is reversibly reduced to Cr(III) at a platinum electrode. The diffusion coefficient for Cr(VI) at 800 0 C is 1,9.10 -7 cm 2 .s -1 [fr

Coupling of an indicator-free electrochemical DNA biosensor with polymerase chain reaction for the detection of DNA sequences related to the apolipoprotein E

Energy Technology Data Exchange (ETDEWEB)

Lucarelli, Fausto; Marrazza, Giovanna; Palchetti, Ilaria; Cesaretti, S.; Mascini, Marco

2002-09-26

This paper describes a disposable indicator-free electrochemical DNA biosensor applied to the detection of apolipoprotein E (apoE) sequences in PCR samples. In the indicator-free assays, the duplex formation was detected by measuring the electrochemical signal of the guanine base of nucleic acids. The biosensor format involved the immobilisation of an inosine-modified (guanine-free) probe onto a screen-printed electrode (SPE) transducer and the detection of the duplex formation in connection with the square-wave voltammetric measurement of the oxidation peak of the guanine of the target sequence. The indicator-free scheme has been characterised using 23-mer oligonucleotides as model: parameters affecting the hybridisation assay such as probe immobilisation conditions, hybridisation time, use of hybridisation accelerators were examined and optimised. The analysis of PCR samples (244 bp DNA fragments, obtained by amplification of DNA extracted from human blood) required a further optimisation of the experimental procedure. In particular, a lower steric hyndrance of the probe modified surface was essential to allow an efficient hybridisation of the target DNA fragment. Negative controls have been performed using the PCR blank and amplicons unrelated to the immobilised probe. A 10 min hybridisation time allowed a full characterisation of each sample.

Characterisation of areal surface texture

CERN Document Server

Leach, Richard

2014-01-01

This book presents the areal framework that is being adopted by the international community, concentrating on characterisation methods, and presenting case studies highlighting use of areal methods in applications from automobile manufacturing to archaeology.

Kinetic studies of electrochemical generation of Ag(II) ion and catalytic oxidation of selected organics

International Nuclear Information System (INIS)

Zawodzinski, C.; Smith, W.H.; Martinez, K.R.

1993-01-01

The goal of this research is to develop a method to treat mixed hazardous wastes containing selected organic compounds and heavy metals, including actinide elements. One approach is to destroy the organic via electrochemical oxidation to carbon dioxide, then recover the metal contaminants through normally accepted procedures such as ion exchange, precipitation, etc. The authors have chosen to study the electrochemical oxidation of a simple alcohol, iso-propanol. Much of the recent work reported involved the use of an electron transfer mediator, usually the silver(I)/(II) redox couple. This involved direct electrochemical generation of the mediator at the anode of a divided cell followed by homogeneous reaction of the mediator with the organic compound. In this study the authors have sought to compare the mediated reaction with direct electrochemical oxidation of the organic. In addition to silver(I)/(II) they also looked at the cobalt(II)/(III) redox coupled. In the higher oxidation state both of these metal ions readily hydrolyze in aqueous solution to ultimately form insoluble oxide. The study concluded that in a 6M nitric acid solution at room temperature iso-propanol can be oxidized to carbon dioxide and acetic acid. Acetic acid is a stable intermediate and resists further oxidation. The presence of Co(III) enhances the rate or efficiency of the reaction

Electrochemical, morphological and microstructural characterization of carbon film resistor electrodes for application in electrochemical sensors

International Nuclear Information System (INIS)

Gouveia-Caridade, Carla; Soares, David M.; Liess, Hans-Dieter; Brett, Christopher M.A.

2008-01-01

The electrochemical and microstructural properties of carbon film electrodes made from carbon film electrical resistors of 1.5, 15, 140 Ω and 2.0 kΩ nominal resistance have been investigated before and after electrochemical pre-treatment at +0.9 V vs SCE, in order to assess the potential use of these carbon film electrodes as electrochemical sensors and as substrates for sensors and biosensors. The results obtained are compared with those at electrodes made from previously investigated 2 Ω carbon film resistors. Cyclic voltammetry was performed in acetate buffer and phosphate buffer saline electrolytes and the kinetic parameters of the model redox system Fe(CN) 6 3-/4- obtained. The 1.5 Ω resistor electrodes show the best properties for sensor development with wide potential windows, similar electrochemical behaviour to those of 2 Ω and close-to-reversible kinetic parameters after electrochemical pre-treatment. The 15 and 140 Ω resistor electrodes show wide potential windows although with slower kinetics, whereas the 2.0 kΩ resistor electrodes show poor cyclic voltammetric profiles even after pre-treatment. Electrochemical impedance spectroscopy related these findings to the interfacial properties of the electrodes. Microstructural and morphological studies were carried out using contact mode Atomic Force Microscopy (AFM), Confocal Raman spectroscopy and X-ray diffraction. AFM showed more homogeneity of the films with lower nominal resistances, related to better electrochemical characteristics. X-ray diffraction and Confocal Raman spectroscopy indicate the existence of a graphitic structure in the carbon films

Characterisation of mouse prothymocytes

NARCIS (Netherlands)

W.J.A. Boersma (Wim)

1982-01-01

textabstractIn this thesis, the study of growth kinetics of thymocytes in lethally irradiated mice as a means to characterise the early T-cell progenitors is described. Normal bone marrow cells were used as the source of hemopoietic cells. The experiments show that it is possible to obtain

Testing new methodologies and assessing their potential for reservoir characterisation: Geoelectrical studies in the Northwest Carboniferous Basin (Ireland).

Science.gov (United States)

Ogaya, Xènia; Campanyà, Joan; Rath, Volker; Jones, Alan G.; Reay, Derek; Raine, Rob; McConnell, Brian; Ledo, Juanjo

2016-04-01

The overarching objective of this study is to improve our methods of characterising saline aquifers by integrating newly acquired electromagnetic data with existing geophysical and geological data. The work presented here is part of an ongoing project to evaluate Ireland's potential for onshore carbon sequestration (IRECCSEM; funded by Science Foundation Ireland). The methodology presented in this characterisation work is not only relevant for studying the potential for onshore carbon sequestration, but is generally applicable for aquifer characterisation, particularly for the evaluation of geothermal resources in appropriate geological settings. We present first results of the three-dimensional (3D) modelling and inversion of the magnetotelluric (MT) data acquired in the Northwest Carboniferous Basin (Ireland) in summer 2015. The electrical resistivity distribution beneath the survey area is constrained using a joint inversion of three different types of electromagnetic data: MT impedance tensor responses (Z), geomagnetic transfer functions (GTF) and inter-station horizontal magnetic transfer-functions (HMT). The preliminary 3D resistivity model obtained reveals the geoelectrical structure of the subsurface, which is translated into parameters relevant to fluid flow. The electromagnetic data were acquired along profiles linking four wells drilled in the area and the available well log data from those wells are used to evaluate some of the existing petrophysical relationships and calibrate them for the study area. This allows us to interpolate the rock physical properties from one well to another well, using the computed geoelectrical model as a reference. The obtained results are compared to available independent geological and geophysical data in order to analyse the validity of this technique, to characterise the uncertainties inherent to our approach, and to assess the potential of this methodology for reservoir characterisation.

Optical and electrochemical studies of polyaniline/SnO2 fibrous nanocomposites

International Nuclear Information System (INIS)

Manivel, P.; Ramakrishnan, S.; Kothurkar, Nikhil K.; Balamurugan, A.; Ponpandian, N.; Mangalaraj, D.; Viswanathan, C.

2013-01-01

Graphical abstract: Fiber with porous like structure of PANI/SnO 2 nanocomposites were prepared by simplest in situ chemical polymerization method. The PL emission spectra revealed that the band from 404 and 436 nm which is related with oxygen vacancies. The excellent electrochemical properties of composite electrode show the specific capacitance of 173 F/g at a scan rate of 25 m V/s. Display Omitted Highlights: ► Self assembled PANI/SnO 2 nanocomposites were synthesized by simple polymerization method. ► Electrochemical behavior of PANI/SnO 2 nanocomposites electrode was analyzed by CV. ► Nanocomposites exhibit a higher specific capacitance of 173 F/g, compared with pure SnO 2 . -- Abstract: Polyaniline (PANI)/tin oxide (SnO 2 ) fibrous nanocomposites were successfully prepared by an in situ chemical polymerization method with suitable conditions. The obtained composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, photoluminescence (PL), electrical conductivity and cyclic voltammetry studies (CV). The XRD pattern of the as-prepared sample shows the presence of tetragonal SnO 2 and the crystalline structure of SnO 2 was not affected with the incorporation of PANI. The FTIR analysis confirms the uniform attachment of PANI on the surface of SnO 2 nanostructures. SEM images show a fibrous agglomerated structure of PANI/SnO 2 . The PL emission spectra revealed that the band from 404 and 436 nm which is related with oxygen vacancies. The electrochemical behavior of the PANI/SnO 2 composite electrode was evaluated in a H 2 SO 4 solution using cyclic voltammetry. The composite electrode exhibited a specific capacitance of 173 F/g at a scan rate 25 mV/s. Thus the as-prepared PANI/SnO 2 composite shows excellent electrochemical properties, suggesting that this composite is a promising material for supercapacitors.

Studies on room temperature electrochemical oxidation and its effect on the transport properties of TBCCO films

International Nuclear Information System (INIS)

Shirage, P M; Shivagan, D D; Pawar, S H

2004-01-01

A novel room temperature electrochemical process for the synthesis of single-phase Tl 2 Ba 2 Ca 2 Cu 3 O 10 (TBCCO/Tl-2223) superconducting films has been developed. Electrochemical parameters were optimized by studying linear sweep voltammetry (LSV), cyclic voltammetry (CV) and chronoamperometry (CA) for the deposition of Tl-Ba-Ca-Cu alloy at room temperature. The superconducting films of the TBCCO were obtained by two oxidation techniques. In the first technique, the electrodeposited Tl-Ba-Ca-Cu alloyed films were oxidized at various temperatures in flowing oxygen atmosphere. In the second technique, stoichiometric electrocrystallization to get Tl 2 Ba 2 Ca 2 Cu 3 O 10 (Tl-2223) was completed by electrochemically intercalating oxygen species into Tl-Ba-Ca-Cu alloy at room temperature for various lengths of time. The oxygen content in the samples was varied by varying the electrochemical oxidation period, and the changes in the crystal structure, superconducting transition temperature (T c ) and critical current density (J c ) were recorded. The high temperature furnace oxidation technique was replaced by the room temperature electrochemical oxidation technique. The dependence of superconducting parameters on oxygen content is correlated with structure-property relations

Characterising the hydrological regime of an ungauged temporary river system: a case study.

Science.gov (United States)

D'Ambrosio, Ersilia; De Girolamo, Anna Maria; Barca, Emanuele; Ielpo, Pierina; Rulli, Maria Cristina

2017-06-01

Temporary streams are characterised by specific hydrological regimes, which influence ecosystem processes, groundwater and surface water interactions, sediment regime, nutrient delivery, water quality and ecological status. This paper presents a methodology to characterise and classify the regime of a temporary river in Southern Italy based on hydrological indicators (HIs) computed with long-term daily flow records. By using a principal component analysis (PCA), a set of non-redundant indices were identified describing the main characteristics of the hydrological regime in the study area. The indicators identified were the annual maximum 30- and 90-day mean (DH4 and DH5), the number of zero flow days (DL6), flow permanence (MF) and the 6-month seasonal predictability of dry periods (SD6). A methodology was also tested to estimate selected HIs in ungauged river reaches. Watershed characteristics such as catchment area, gauging station elevation, mean watershed slope, mean annual rainfall, land use, soil hydraulic conductivity and available water content were derived for each site. Selected indicators were then linked to the catchment characteristics using a regression analysis. Finally, MF and SD6 were used to classify the river reaches on the basis of their degree of intermittency. The methodology presented in this paper constitutes a useful tool for ecologists and water resource managers in the Water Framework Directive implementation process, which requires a characterisation of the hydrological regime and a 'river type' classification for all water bodies.

Electrochemical and DFT study of an anticancer and active anthelmintic drug at carbon nanostructured modified electrode

International Nuclear Information System (INIS)

Ghalkhani, Masoumeh; Beheshtian, Javad; Salehi, Maryam

2016-01-01

The electrochemical response of mebendazole (Meb), an anticancer and effective anthelmintic drug, was investigated using two different carbon nanostructured modified glassy carbon electrodes (GCE). Although, compared to unmodified GCE, both prepared modified electrodes improved the voltammetric response of Meb, the carbon nanotubes (CNTs) modified GCE showed higher sensitivity and stability. Therefore, the CNTs-GCE was chosen as a promising candidate for the further studies. At first, the electrochemical behavior of Meb was studied by cyclic voltammetry and differential pulse and square wave voltammetry. A one step reversible, pH-dependent and adsorption-controlled process was revealed for electro-oxidation of Meb. A possible mechanism for the electrochemical oxidation of Meb was proposed. In addition, electronic structure, adsorption energy, band gap, type of interaction and stable configuration of Meb on the surface of functionalized carbon nanotubes were studied by using density functional theory (DFT). Obtained results revealed that Meb is weakly physisorbed on the CNTs and that the electronic properties of the CNTs are not significantly changed. Notably, CNTs could be considered as a suitable modifier for preparation of the modified electrode for Meb analysis. Then, the experimental parameters affecting the electrochemical response of Meb were optimized. Under optimal conditions, high sensitivity (b(Meb) = dI p,a (Meb) / d[Meb] = 19.65 μA μM −1 ), a low detection limit (LOD (Meb) = 19 nM) and a wide linear dynamic range (0.06–3 μM) was resulted for the voltammetric quantification of Meb. - Highlights: • Electrochemical oxidation mechanism of Meb was investigated. • A carbon nanostructure modified electrode was developed for the determination of Meb. • The modified electrode surface was characterized by SEM and impedance studies. • This study provides an effective chemically modified electrode with satisfactory repeatability and reproducibility

Characterisation of mouse prothymocytes

NARCIS (Netherlands)

Boersma, W.J.A.

1982-01-01

In this thesis, the study of growth kinetics of thymocytes in lethally irradiated mice as a means to characterise the early T-cell progenitors is described. Normal bone marrow cells were used as the source of hemopoietic cells. The experiments show that it is possible to obtain information on T-cell

Electrochemical impedance study of copper in phosphate buffered solution

International Nuclear Information System (INIS)

Salimon, J.; Mohamad, M.; Yamin, B.M.; Kalaji, M.

2003-01-01

The processes occurring on the copper electrode surface in phosphate buffered solution were investigated using the Electrochemical Impedance Spectroscopy. The electrochemical behaviors of copper through their charge transfer resistance and double-layer capacitance at the onset of the hydrogen evolution region and the anodic passivation layer formation and diffusion of copper species at anodic potential regions are discussed. The specific adsorption of anions (hydroxide and/or H/sub 2/PO/sub 4/) occurred at potential less negative than -0.9V. Adsorbed hydrogen appeared at hydrogen evolution region at potential range of -1.5 to -1.0 V. The deposition of insoluble copper species occurred at anodic potential regions. (author)

Electrochemical Performance of Ni-MOFs for Supercapacitors

Science.gov (United States)

Li, Yujuan; Song, Lili; Han, Yinghui; Wang, Guangyou

2018-03-01

In this work, the Ni-MOFs of electrode material has been synthesized, characterized and studied for the electrochemical properties of electrode materials. The effects of the doping amount of Ni, calcination temperature and time were studied in detail. The results suggested that the electrochemical properties were obviously improved by the Ni-MOFs of electrode material and the best preparation conditions can also improve the electrochemical properties of electrode materials. These results open a way for the design of tailored MOFs as electrode materials for supercapacitors.

The use of odd random phase electrochemical impedance spectroscopy to study lithium-based corrosion inhibition by active protective coatings

NARCIS (Netherlands)

Meeusen, M.; Visser, P.; Fernández Macía, L.; Hubin, A.; Terryn, H.A.; Mol, J.M.C.

2018-01-01

In this work, the study of the time-dependent behaviour of lithium carbonate based inhibitor technology for the active corrosion protection of aluminium alloy 2024-T3 is presented. Odd random phase electrochemical impedance spectroscopy (ORP-EIS) is selected as the electrochemical tool to study

Use of electrochemical techniques to study the corrosion of metals in model fluoride melts

Energy Technology Data Exchange (ETDEWEB)

Fabre, S. [EDF R and D, Département MMC, Groupe Chimie et Corrosion, 77818 Moret-sur-Loing Cedex (France); Cabet, C., E-mail: celine.cabet@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d’Etude de la Corrosion Non Aqueuse, F-91191 Gif-sur-Yvette (France); Cassayre, L.; Chamelot, P. [Université Toulouse, INPT, UPS, Laboratoire de Génie Chimique, Département Procédés Electrochimiques, F-31062 Toulouse Cedex 09 (France); Delepech, S. [ENSCP, Laboratoire d’Électrochimie, de Chimie des Interface et Modélisation pour l’Energie, UMR 7575, 11 rue Pierre et Marie Curie, 75232 Paris Cedex 5 (France); Finne, J. [EDF R and D, Département MMC, Groupe Chimie et Corrosion, 77818 Moret-sur-Loing Cedex (France); Massot, L. [Université Toulouse, INPT, UPS, Laboratoire de Génie Chimique, Département Procédés Electrochimiques, F-31062 Toulouse Cedex 09 (France); Noel, D. [EDF R and D, Département MMC, Groupe Chimie et Corrosion, 77818 Moret-sur-Loing Cedex (France)

2013-10-15

Molten fluorides are appealing coolants for innovative nuclear systems but structural alloys may undergo corrosion at high temperature. Because corrosion primarily occurs via electrochemical reactions, electrochemical techniques are ideal for the study of corrosion thermochemistry and kinetics. Examples are given. An electrochemical series was established using voltammetry in LiF–NaF at 1173 K. Stability increases in the following order: Na, Cr, Fe, Ni, Mo/W, Ag, Au. Various alloys were also classified according to their oxidation resistance. A cathodic protection method was developed to curb the intergranular attack of some nickel alloys in molten LiF–CaF{sub 2}–MgF{sub 2}–ZrF{sub 4} containing tellurium vapor at 953 K. Voltammetry and polarization resistance measurement were used to estimate the rate of chromium selective dissolution for nickel base alloys immersed in LiF–NaF at 1073 K and 1173 K.

Characterisation of carbon nanotubes in the context of toxicity studies

Science.gov (United States)

Berhanu, D.; Dybowska, A.; Misra, S.K.; Stanley, C.J.; Ruenraroengsak, P.; Boccaccini, A.R.; Tetley, T.D.; Luoma, S.N.; Plant, J.A.; Valsami-Jones, E.

2009-01-01

Nanotechnology has the potential to revolutionise our futures, but has also prompted concerns about the possibility that nanomaterials may harm humans or the biosphere. The unique properties of nanoparticles, that give them novel size dependent functionalities, may also have the potential to cause harm. Discrepancies in existing human health and environmental studies have shown the importance of good quality, well-characterized reference nanomaterials for toxicological studies. Here we make a case for the importance of the detailed characterization of nanoparticles, using several methods, particularly to allow the recognition of impurities and the presence of chemically identical but structurally distinct phases. Methods to characterise fully, commercially available multi-wall carbon nanotubes at different scales, are presented. ?? 2009 Berhanu et al; licensee BioMed Central Ltd.

CCS site characterisation criteria

Energy Technology Data Exchange (ETDEWEB)

Bachu, S.; Hawkes, C.; Lawton, D.; Pooladi-Darvish, M.; Perkins, E.

2009-12-15

IEA GHG recently commissioned the Alberta Research Counil in Canada to conduct a review of storage site selection criteria and site characterisation methods in order to produce a synthesis report. This report reviews the literature on the subject on the site seleciton and characterisation since the publication of the IPCC Special Report on CCS, and provides a synthesis and classification of criteria. 161 refs.

An electrochemical study of neutral red-DNA interaction

International Nuclear Information System (INIS)

Heli, H.; Bathaie, S.Z.; Mousavi, M.F.

2005-01-01

Electrochemical methods were used to investigate the interaction of neutral red (NR) with double-stranded calf thymus DNA, in solution as well as using a DNA-modified glassy carbon (GC-DNA) electrode. The results were compared with those obtained from bare glassy carbon (GC) electrode. The formal potential of NR was more positive when GC-DNA electrode was used although the rate of heterogeneous electron transfer is as high as that of using GC electrode. GC-DNA electrode enables preconcentration of NR for chosen times on the electrode surface, despite the fact that the mass transfer effects in the thin DNA layer adsorbed on the surface was still observed using cyclic voltammetry and electrochemical impedance spectroscopy techniques. Parameters, such as the diffusion coefficient of NR, binding site size in base pairs and the ratio of the binding constants for the oxidized and reduced forms of the bound species were obtained. A binding isotherm for NR at GC-DNA electrode was obtained from coulometric titrations and gave an affinity constant equal to 2.76 x 10 4 L mol -1 . From the studies of the interaction in solution, the diffusion coefficient of free and DNA-bound NR, binding constant and binding site size of the DNA-NR complex was also obtained simultaneously by non-linear fitting analysis of voltammetric data

Diazonium salt derivatives of osmium bipyridine complexes: Electrochemical grafting and characterisation of modified surfaces

International Nuclear Information System (INIS)

Garrett, David J.; Jenkins, Peter; Polson, Matthew I.J.; Leech, Donal; Baronian, Keith H.R.; Downard, Alison J.

2011-01-01

Osmium bipyridine complexes were directly grafted to carbon electrodes through electroreduction of the diazonium salts [Os(bpy-ph-N 2 + ) 3 ](PF 6 ) 5 (1) and [Os(bpy-ph-N 2 + ) 2 Cl 2 ](PF 6 ) 2 (2). Growth of the films was not self-limiting as is usually found for grafting from diazonium salts. It appears that electron hopping through the bipyridine ligands of the immobilised complexes enables film growth to continue at a constant rate during grafting by potential cycling. The surface concentrations of deposited films were measured electrochemically and the film thicknesses were measured by depth-profiling using the atomic force microscope. Films up to 42 nm thick were prepared with no evidence for slowing of film growth. The grafted films exhibited high stability when repetitively cycled through the Os 2+/3+ couple and electron transfer rate constants of 11.4 s -1 and 35.4 s -1 were measured in ACN and PBS, respectively, for the Os 2+/3+ couple of the film grafted from 1.

Effect of the electrochemical technique on nanocrystalline ZnO electrodeposition, its structural, morphological and photoelectrochemical properties

Energy Technology Data Exchange (ETDEWEB)

Chettah, Hamdane; Abdi, Djamila, E-mail: naimadjam@hotmail.com

2013-06-30

This article reports the influence of the electrochemical technique on the electrodeposition of nanoscopic zinc oxide from aqueous mixed bath of zinc nitrate and potassium chloride at 70 °C onto fluorine doped tin oxide coated glass substrates. ZnO thin films were elaborated via cyclic voltamperometry and chronoamperometry techniques. This study shows structural and morphological differences in films deposited according to both methods. Thin and adherent films obtained via cyclic voltamperometry have been obtained after 100 cycles, and those obtained using the chronoampermetric method grown at potential of − 1 V vs. Ag/AgCl during 1 h. The structural characterisation of such films was performed using X-ray diffraction, which showed the most important peaks of ZnO wurtzite structure with preferential orientation along the (002) axis for deposits obtained via cyclic voltamperometry presenting nanometric grain sizes (42 nm). Atomic force microscopy was used to study surface morphology and estimate the surface roughness factor for two deposits. Photoelectrochemical study indicates that both kinds of films had n-type electrical conductivity and presents high photoanodic-generated currents. - Highlights: • Zinc oxide films were electrodeposited on fluorine doped tin oxide substrates at 70 °C. • Two electrochemical techniques were used cyclic voltamperometry and chronoamperometry. • X-ray diffraction showed the most important peaks of ZnO wurtzite structure. • Preferential orientation along the (002) axis for cyclic voltamperometry films. • Deposits had n-type electrical conductivity and high photoanodic-generated currents.

Electrochemical surface plasmon spectroscopy-Recent developments and applications

International Nuclear Information System (INIS)

Zhang, Nan; Schweiss, Ruediger; Zong, Yun; Knoll, Wolfgang

2007-01-01

A survey is given on recent developments and applications of electrochemical techniques combined with surface plasmon resonance (SPR) spectroscopy. Surface plasmon spectroscopy (SPS) and optical waveguide mode spectroscopy make use of evanescent waves on metal-dielectric interfaces and can be conveniently combined with electrochemical methods. Selected examples of applications of high-pressure surface electrochemical plasmon resonance spectroscopy to study supramolecular architectures such as layer-by-layer films of conducting polymers or thin composite films will be presented. Then a combination of SPS with the electrochemical quartz crystal microbalance (EQCM) will be introduced and illustrated with a study on doping/de-doping process of a conducting polymer. This combination allows for simultaneous electrochemical, optical and microgravimetric characterization of interfaces. Finally, new technical developments including integration of SPS into microfluidic devices using a grating coupler and surface plasmon enhanced diffraction will be discussed

Electrochemical Dissolution of Iridium and Iridium Oxide Particles in Acidic Media: Transmission Electron Microscopy, Electrochemical Flow Cell Coupled to Inductively Coupled Plasma Mass Spectrometry, and X-ray Absorption Spectroscopy Study.

Science.gov (United States)

Jovanovič, Primož; Hodnik, Nejc; Ruiz-Zepeda, Francisco; Arčon, Iztok; Jozinović, Barbara; Zorko, Milena; Bele, Marjan; Šala, Martin; Šelih, Vid Simon; Hočevar, Samo; Gaberšček, Miran

2017-09-13

Iridium-based particles, regarded as the most promising proton exchange membrane electrolyzer electrocatalysts, were investigated by transmission electron microscopy and by coupling of an electrochemical flow cell (EFC) with online inductively coupled plasma mass spectrometry. Additionally, studies using a thin-film rotating disc electrode, identical location transmission and scanning electron microscopy, as well as X-ray absorption spectroscopy have been performed. Extremely sensitive online time-and potential-resolved electrochemical dissolution profiles revealed that Ir particles dissolve well below oxygen evolution reaction (OER) potentials, presumably induced by Ir surface oxidation and reduction processes, also referred to as transient dissolution. Overall, thermally prepared rutile-type IrO 2 particles are substantially more stable and less active in comparison to as-prepared metallic and electrochemically pretreated (E-Ir) analogues. Interestingly, under OER-relevant conditions, E-Ir particles exhibit superior stability and activity owing to the altered corrosion mechanism, where the formation of unstable Ir(>IV) species is hindered. Due to the enhanced and lasting OER performance, electrochemically pre-oxidized E-Ir particles may be considered as the electrocatalyst of choice for an improved low-temperature electrochemical hydrogen production device, namely a proton exchange membrane electrolyzer.

Electrochemical behavior of pitch-based activated carbon fibers for electrochemical capacitors

International Nuclear Information System (INIS)

Lee, Hye-Min; Kwac, Lee-Ku; An, Kay-Hyeok; Park, Soo-Jin; Kim, Byung-Joo

2016-01-01

Highlights: • Electrode materials for electrochemical capacitors were developed using pitch-based activated carbon fibers with steam activation. • Activated carbon fibers showed enhanced specific surface area from 1520 to 3230 m 2 /g. • The increase in the specific capacitance of the samples was determined by charged pore structure during charging and discharging. - Abstract: In the present study, electrode materials for electrochemical capacitors were developed using pitch-based activated carbon fibers with steam activation. The surface and structural characteristics of activated carbon fibers were observed using scanning electron microscopy and X-ray diffraction, respectively. Pore characteristics were investigated using N 2 /77 K adsorption isotherms. The activated carbon fibers were applied as electrodes for electrical double-layer capacitors and analyzed in relation to the activation time. The specific surface area and total pore volume of the activated carbon fibers were determined to be 1520–3230 m 2 /g and 0.61–1.87 cm 3 /g, respectively. In addition, when the electrochemical characteristics were analyzed, the specific capacitance was confirmed to have increased from 1.1 F/g to 22.5 F/g. From these results, it is clear that the pore characteristics of pitch-based activated carbon fibers changed considerably in relation to steam activation and charge/discharge cycle; therefore, it was possible to improve the electrochemical characteristics of the activated carbon fibers.

Corrosion Study Using Electrochemical Impedance Spectroscopy

Science.gov (United States)

Farooq, Muhammad Umar

2003-01-01

Corrosion is a common phenomenon. It is the destructive result of chemical reaction between a metal or metal alloy and its environment. Stainless steel tubing is used at Kennedy Space Center for various supply lines which service the orbiter. The launch pads are also made of stainless steel. The environment at the launch site has very high chloride content due to the proximity to the Atlantic Ocean. Also, during a launch, the exhaust products in the solid rocket boosters include concentrated hydrogen chloride. The purpose of this project was to study various alloys by Electrochemical Impedance Spectroscopy in corrosive environments similar to the launch sites. This report includes data and analysis of the measurements for 304L, 254SMO and AL-6XN in primarily neutral 3.55% NaCl. One set of data for 304L in neutral 3.55%NaCl + 0.1N HCl is also included.

Electrochemical and AFM Characterization of G-Quadruplex Electrochemical Biosensors and Applications

Science.gov (United States)

2018-01-01

Guanine-rich DNA sequences are able to form G-quadruplexes, being involved in important biological processes and representing smart self-assembling nanomaterials that are increasingly used in DNA nanotechnology and biosensor technology. G-quadruplex electrochemical biosensors have received particular attention, since the electrochemical response is particularly sensitive to the DNA structural changes from single-stranded, double-stranded, or hairpin into a G-quadruplex configuration. Furthermore, the development of an increased number of G-quadruplex aptamers that combine the G-quadruplex stiffness and self-assembling versatility with the aptamer high specificity of binding to a variety of molecular targets allowed the construction of biosensors with increased selectivity and sensitivity. This review discusses the recent advances on the electrochemical characterization, design, and applications of G-quadruplex electrochemical biosensors in the evaluation of metal ions, G-quadruplex ligands, and other small organic molecules, proteins, and cells. The electrochemical and atomic force microscopy characterization of G-quadruplexes is presented. The incubation time and cations concentration dependence in controlling the G-quadruplex folding, stability, and nanostructures formation at carbon electrodes are discussed. Different G-quadruplex electrochemical biosensors design strategies, based on the DNA folding into a G-quadruplex, the use of G-quadruplex aptamers, or the use of hemin/G-quadruplex DNAzymes, are revisited. PMID:29666699

Electrochemical studies of redox probes in self-organized lyotropic ...

Indian Academy of Sciences (India)

Administrator

quinone|hydroquinone, methyl viologen and ferrocenemethanol probes in a lyotropic hexagonal columnar phase (H1 phase) using cyclic voltammetry and electrochemical impedance ..... hydrogen bond of hydroquinone during oxidation is.

Electrochemical remediation of copper contaminated clay soils

Energy Technology Data Exchange (ETDEWEB)

Korolev, V.A.; Babakina, O.A.; Mitojan, R.A. [Moscow State Univ. (Russian Federation)

2001-07-01

The study objective focused on electrochemical remediation copper polluted soils in the presence of adjuvant substances and conditions that are more effective for the treatment. Some of these substances were studied in different researches. Moreover, authors obtained a result of extraction copper rate higher than 90%. In this connection the following problems were set: - Influence organic and inorganic substances on copper mobility in soil under the DC current. - Moisture effect on copper migration in clay. - Electrochemical remediation soils different mineralogical composition. - A washing conditions contribution to electrochemical remediation of soil from copper. - Accuracy rating experimental dates. (orig.)

A dual-electrochemical cell to study the biocorrosion of stainless steel.

Science.gov (United States)

Lopes, F A; Perrin, S; Féron, D

2007-01-01

The presence of microorganisms on metal surfaces can alter the local physical/chemical conditions and lead to microbiologically influenced corrosion (MIC). The goal of the present work was to study the effect of a mixed aerobic-anaerobic biofilm on the behaviour of stainless steel (316 L) in underground conditions. Rather than testing different bacteria or consortia, investigations were based on the mechanisms of MIC. Mixed biofilms were simulated by the addition of glucose oxidase to reproduce the aerobic conditions and by sulphide or sulphate-reducing bacteria (SRB) for the anaerobic conditions. A double thermostated electrochemical cell has been developed to study the coupling between aerobic and anaerobic conditions. Results suggested a transfer of electrons from the stainless steel sample of the anaerobic cell to the stainless steel sample of the aerobic one. Inorganic sulphide was replaced by SRB in the anaerobic cell revealing an increase of the galvanic current which may be explained by an effect of lactate and/or acetate on the anodic reaction or by a high sulphide concentration in the biofilm. The results of this study underline that the dual-electrochemical cell system is representative of phenomena present in natural environments and should be considered as an option when studying MIC.

Fundamental Studies on the Electrochemical Behaviour of Carbon Steel Exposed in Sulphide and Sulphate-Reducing Environments

DEFF Research Database (Denmark)

Hilbert, Lisbeth Rischel

The aim of the report is to give a fundamental understanding of the response of different electrochemical techniques on carbon steel in a sulphide environment as well as in a biologically active sulphate-reducing environment (SRB). This will form the basis for further studies and for recommendati......The aim of the report is to give a fundamental understanding of the response of different electrochemical techniques on carbon steel in a sulphide environment as well as in a biologically active sulphate-reducing environment (SRB). This will form the basis for further studies...

Electrochemical and weight-loss study of carbon steel corrosion

International Nuclear Information System (INIS)

Thomas, V.J.; Olive, R.P.

2007-01-01

The Point Lepreau Generating Station (PLGS) will undergo an 18 month refurbishment project beginning in April, 2008. During this time, most of the carbon steel piping in the primary loop will be drained of water and dried. However, some water will remain during the shutdown due to the lack of drains in some lower points in the piping system. As a result, it is necessary to examine the effect of corrosion during the refurbishment. This study examined the effect of several variables on the corrosion rate of clean carbon steel. Specifically, the effect of oxygen in the system and the presence of chloride ions were evaluated. Corrosion rates were determined using both a weight-loss technique and electrochemical methods. The experiment was conducted at room temperature. The corrosion products from the experiment were analyzed using a Raman microscope. The results of the weight-loss measurements show that the corrosion rate of polished carbon steel is independent of both the presence of oxygen and chloride ions. The electrochemical method failed to yield meaningful results due to the lack of clearly interpretable data and the inherent subjectivity in the analysis. Lepidocricite was found to be the main corrosion product using the Raman microscope. (author)

TXRF study of electrochemical deposition of metals on glass-ceramic carbon electrode surfaces

International Nuclear Information System (INIS)

Alov, N.; Oskolok, K.; Wittershagen, A.; Mertens, M.; Rittmeyer, C.; Kolbesen, B.O.

2000-01-01

Nowadays the methods of solid surface analysis are widely used to study the thermodynamic and kinetic aspects of joint electrochemical deposition of metals on solid substrates. In this work the surfaces of some binary and ternary metal electrodeposits on disc glass-ceramic carbon electrodes were studied by total-reflection x-ray fluorescence spectroscopy (TXRF). Metal alloys were obtained as a result of electrochemical co-deposition of copper, cadmium and lead from n x 10 -4 M (Cu, Cd, Pb)(NO 3 ) 2 + 0.01 M HNO 3 solutions under mixing. TXRF measurements were performed with an ATOMIKA EXTRA II A spectrometer using Mo K α and W (Brems) primary excitation. The serious advantage of TXRF as a method of near-surface analysis is very high element sensitivity. Apart from main elements (Cu, Cd, Pb) we have detected trace elements (Cl, Ag, Pt, Hg) which are present in working solution and has an effect to the electrodeposit formation. The comparison of TXRF data with information obtained by X-ray photoelectron spectroscopy and electron-probe x-ray microanalysis permits to realize depth profiling electrochemical alloys. In particular it was found that in binary systems Cu-Pb and Cu-Cd the relative lead and cadmium content on the electrodeposit surface is considerably greater than in the bulk. These phenomena are due to the features of metal nucleation and growth mechanisms. High sensitivity of TXRF to surface morphology and the correlation of TXRF and scanning electron microscopy data allow to determine the area of prevailing location of metal in the heterogeneous alloy surface. So we have established that in Cu-Pb and Cu-Cd-Pb systems solid solution of copper and lead is formed: significant part of lead is deposited not only in specific 3D-clusters but also in copper thin film. It was demonstrated that the near-surface TXRF analysis of metal electrodeposits on solid electrodes is highly effective to study the mechanisms of metal nucleation, metal cluster and thin film

Electrochemical studies of Copper, Tantalum and Tantalum Nitride surfaces in aqueous solutions for applications in chemical-mechanical and electrochemical-mechanical planarization

Science.gov (United States)

Sulyma, Christopher Michael

This report will investigate fundamental properties of materials involved in integrated circuit (IC) manufacturing. Individual materials (one at a time) are studied in different electrochemical environmental solutions to better understand the kinetics associated with the polishing process. Each system tries to simulate a real CMP environment in order to compare our findings with what is currently used in industry. To accomplish this, a variety of techniques are used. The voltage pulse modulation technique is useful for electrochemical processing of metal and alloy surfaces by utilizing faradaic reactions like electrodeposition and electrodissolution. A theoretical framework is presented in chapter 4 to facilitate quantitative analysis of experimental data (current transients) obtained in this approach. A typical application of this analysis is demonstrated for an experimental system involving electrochemical removal of copper surface layers, a relatively new process for abrasive-free electrochemical mechanical planarization of copper lines used in the fabrication of integrated circuits. Voltage pulse modulated electrodissolution of Cu in the absence of mechanical polishing is activated in an acidic solution of oxalic acid and hydrogen peroxide. The current generated by each applied voltage step shows a sharp spike, followed by a double-exponential decay, and eventually attains the rectangular shape of the potential pulses. For the second system in chapter 5, open-circuit potential measurements, cyclic voltammetry and Fourier transform impedance spectroscopy have been used to study pH dependent surface reactions of Cu and Ta rotating disc electrodes (RDEs) in aqueous solutions of succinic acid (SA, a complexing agent), hydrogen peroxide (an oxidizer), and ammonium dodecyl sulfate (ADS, a corrosion inhibitor for Cu). The surface chemistries of these systems are relevant for the development of a single-slurry approach to chemical mechanical planarization (CMP) of Cu

Electrochemical study of the tarnish layer of silver deposited on glass

OpenAIRE

Ben Amor , Yasser; Sutter , Eliane; Takenouti , Hisasi; Tribollet , Bernard; Boinet , M.; Faure , R.; Balencie , J.; Durieu , G.

2014-01-01

International audience; Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the tarnished thin layer of silver deposited on glass. Instead of natural tarnishing in air environment, an acceleration of tarnishing process was realized by immersion of Ag covered glass in 10 μM K2S medium. The X-ray photoelectron spectroscopy (XPS) shows that tarnishing product formed on the silver surface consisted of Ag2S and Ag2O. As electrochemical characterizatio...

Electrochemical thermodynamic measurement system

Science.gov (United States)

Reynier, Yvan [Meylan, FR; Yazami, Rachid [Los Angeles, CA; Fultz, Brent T [Pasadena, CA

2009-09-29

The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.

Electrochemical impedance spectroscopy of oxidized porous silicon

Energy Technology Data Exchange (ETDEWEB)

Mula, Guido, E-mail: guido.mula@unica.it [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Tiddia, Maria V. [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Ruffilli, Roberta [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Falqui, Andrea [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Palmas, Simonetta; Mascia, Michele [Dipartimento di Ingegneria Meccanica Chimica e dei Materiali, Università degli Studi di Cagliari, Piazza d' Armi, 09126 Cagliari (Italy)

2014-04-01

We present a study of the electrochemical oxidation process of porous silicon. We analyze the effect of the layer thickness (1.25–22 μm) and of the applied current density (1.1–11.1 mA/cm{sup 2}, values calculated with reference to the external samples surface) on the oxidation process by comparing the galvanostatic electrochemical impedance spectroscopy (EIS) measurements and the optical specular reflectivity of the samples. The results of EIS were interpreted using an equivalent circuit to separate the contribution of different sample parts. A different behavior of the electrochemical oxidation process has been found for thin and thick samples: whereas for thin samples the oxidation process is univocally related to current density and thickness, for thicker samples this is no more true. Measurements by Energy Dispersive Spectroscopy using a Scanning Electron Microscopy confirmed that the inhomogeneity of the electrochemical oxidation process is increased by higher thicknesses and higher currents. A possible explanation is proposed to justify the different behavior of thin and thick samples during the electrochemical process. - Highlights: • A multidisciplinary approach on porous Si electrochemical oxidation is proposed. • Electrochemical, optical, and structural characterizations are used. • Layer thickness and oxidation current effects are shown. • An explanation of the observed behavior is proposed.

Diazonium salt derivatives of osmium bipyridine complexes: Electrochemical grafting and characterisation of modified surfaces

Energy Technology Data Exchange (ETDEWEB)

Garrett, David J. [MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Jenkins, Peter [School of Chemistry, National University of Ireland, Galway (Ireland); Polson, Matthew I.J. [Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Leech, Donal [School of Chemistry, National University of Ireland, Galway (Ireland); Baronian, Keith H.R. [School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch (New Zealand); Downard, Alison J., E-mail: alison.downard@canterbury.ac.n [MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch (New Zealand)

2011-02-01

Osmium bipyridine complexes were directly grafted to carbon electrodes through electroreduction of the diazonium salts [Os(bpy-ph-N{sub 2}{sup +}){sub 3}](PF{sub 6}){sub 5} (1) and [Os(bpy-ph-N{sub 2}{sup +}){sub 2}Cl{sub 2}](PF{sub 6}){sub 2} (2). Growth of the films was not self-limiting as is usually found for grafting from diazonium salts. It appears that electron hopping through the bipyridine ligands of the immobilised complexes enables film growth to continue at a constant rate during grafting by potential cycling. The surface concentrations of deposited films were measured electrochemically and the film thicknesses were measured by depth-profiling using the atomic force microscope. Films up to 42 nm thick were prepared with no evidence for slowing of film growth. The grafted films exhibited high stability when repetitively cycled through the Os{sup 2+/3+} couple and electron transfer rate constants of 11.4 s{sup -1} and 35.4 s{sup -1} were measured in ACN and PBS, respectively, for the Os{sup 2+/3+} couple of the film grafted from 1.

The pharmacokinetic study of rutin in rat plasma based on an electrochemically reduced graphene oxide modified sensor

Directory of Open Access Journals (Sweden)

Pei Zhang

2016-04-01

Full Text Available An electrochemical method based on a directly electrochemically reduced graphene oxide (ERGO film coated on a glassy carbon electrode (GCE was developed for the rapid and convenient determination of rutin in plasma. ERGO was modified on the surface of GCE by one-step electro-deposition method. Electrochemical behavior of rutin on ERGO/GCE indicated that rutin underwent a surface-controlled quasi-reversible process and the electrochemical parameters such as charge transfer coefficient (α, electron transfer number (n and electrode reaction standard rate constant (ks were 0.53, 2 and 3.4 s−1, respectively. The electrochemical sensor for rutin in plasma provided a wide linear response range of 4.70×10−7−1.25×10−5 M with the detection limit (s/n=3 of 1.84×10−8 M. The assay was successfully used to the pharmacokinetic study of rutin. The pharmacokinetic parameters such as elimination rate half-life (t1/2, area under curve (AUC, and plasma clearance (CL were calculated to be 3.345±0.647 min, 5750±656.0 µg min/mL, and 5.891±0.458 mL/min/kg, respectively. The proposed method utilized a small sample volume of 10 μL and had no complicated sample pretreatment (without deproteinization, which was simple, eco-friendly, and time- and cost-efficient for rutin pharmacokinetic studies.

Electrochemical corrosion study of Mg–Al–Zn–Mn alloy in aqueous ethylene glycol containing chloride ions

Directory of Open Access Journals (Sweden)

Harish Medhashree

2017-01-01

Full Text Available Nowadays most of the automobiles use magnesium alloys in the components of the engine coolant systems. These engine coolants used are mainly composed of aqueous ethylene glycol along with some inhibitors. Generally the engine coolants are contaminated by environmental anions like chlorides, which would enhance the rate of corrosion of the alloys used in the coolant system. In the present study, the corrosion behavior of Mg–Al–Zn–Mn alloy in 30% (v/v aqueous ethylene glycol containing chloride anions at neutral pH was investigated. Electrochemical techniques, such as potentiodynamic polarization method, cyclic polarization and electrochemical impedance spectroscopy (EIS were used to study the corrosion behavior of Mg–Al–Zn–Mn alloy. The surface morphology, microstructure and surface composition of the alloy were studied by using the scanning electron microscopy (SEM, optical microscopy and energy dispersion X-ray (EDX analysis, respectively. Electrochemical investigations show that the rate of corrosion increases with the increase in chloride ion concentration and also with the increase in medium temperature.

Electrochemical studies of Pu on prussian blue (PB)-gold nanoparticles (AuNPs) functionalized glassy carbon (GC) electrode

International Nuclear Information System (INIS)

Sharma, Manoj K.; Ambolikar, Arvind S.; Aggarwal, Suresh K.

2011-01-01

In electrochemical processes, electron transfer across the solid-liquid interface is the elementary step and electron transfer kinetics is significantly influenced by the interfacial properties. Therefore, preparation of well-defined electrochemical interface with highly controllable properties - larger effective surface area, increased mass transport, and better electronic interaction between the analyte and electrode - is significant for both fundamental and applied studies in electrochemistry. In the present work electrochemistry of Pu(IV)/Pu(III) is studied on multilayered AuNPs-PB-AuNPs functionalized electrode

Small-angle neutron scattering and cyclic voltammetry study on electrochemically oxidized and reduced pyrolytic carbon

International Nuclear Information System (INIS)

Braun, A.; Kohlbrecher, J.; Baertsch, M.; Schnyder, B.; Koetz, R.; Haas, O.; Wokaun, A.

2004-01-01

The electrochemical double layer capacitance and internal surface area of a pyrolytic carbon material after electrochemical oxidation and subsequent reduction was studied with cyclic voltammetry and small-angle neutron scattering. Oxidation yields an enhanced internal surface area (activation), and subsequent reduction causes a decrease of this internal surface area. The change of the Porod constant, as obtained from small-angle neutron scattering, reveals that the decrease in internal surface area is not caused merely by a closing or narrowing of the pores, but by a partial collapse of the pore network

Boron-doped Diamond Electrodes: Electrochemical, Atomic Force Microscopy and Raman Study towards Corrosion-modifications at Nanoscale

International Nuclear Information System (INIS)

Kavan, Ladislav; Vlckova Zivcova, Zuzana; Petrak, Vaclav; Frank, Otakar; Janda, Pavel; Tarabkova, Hana; Nesladek, Milos; Mortet, Vincent

2015-01-01

Highlights: • B-doped diamond is nanostructured by corrosion-driven modifications occurring at carbonaceous impurity sites (sp 2 -carbons). • The electrochemical oxidation partly transforms a hydrogen-terminated diamond surface to O-terminated one, but the electrocatalytic activity of plasmatically O-terminated diamond is not achieved. • In contrast to all usual sp 2 carbons, the Raman spectra of B-doped diamond electrodes do not change upon electrochemical charging/discharging. - Abstract: Comparative studies of boron-doped diamonds electrodes (polycrystalline, single-crystalline, H-/O-terminated, and with different sp 3 /sp 2 ratios) indicate morphological modifications of diamond which are initiated by corrosion at nanoscale. In-situ electrochemical AFM imaging evidences that the textural changes start at non-diamond carbonaceous impurity sites treated at high positive potentials (>2.2 V vs. Ag/AgCl). The primary perturbations subsequently develop into sub-micron-sized craters. Raman spectroscopy shows that the primary erosion site is graphite-like (sp 2 -carbon), which is preferentially removed by anodic oxidation. Other non-diamond impurity, viz. tetrahedral amorphous carbon (t-aC), is less sensitive to oxidative decomposition. The diamond-related Raman features, including the B-doping-assigned modes, are intact during reversible electrochemical charging/discharging, which is a salient difference from all usual sp 2 -carbons. The electrochemical oxidation partly transforms a hydrogen-terminated diamond surface to O-terminated one, but the electrocatalytic activity of plasmatically O-terminated diamond is not achieved for a model redox couple, Fe 3+/2+ . Electrochemical impedance spectra were fitted to six different equivalent circuits. The determination of acceptor concentrations is feasible even for highly-doped diamond electrodes.

Wastes Characterisation from Foundry Activities on European Level

International Nuclear Information System (INIS)

Andres, I.; Ruiz, C.; Ibanez, R.; Viguri, J.; Irabien, A.

1999-01-01

This work presents The results of the eco toxicological characterisation of 22 defined wastes from steel foundry activities. The wastes have been selected from three processes, steel mill (smelting). sand casting and cleaning and finishing of steel products,with the common characteristics of represent an important industrial activity in the area and generated the wastes considered in this study. The eco toxicological characterisation obtained applying the Spanish regulations on hazardous waste is compared to the hazardous attributions considered by the European Union in order to characterise a waste as hazardous (non hazardous). The results allow to conclude that a acceptable concordance between both methodologies is reached and remark the need to split the broad generic types of wastes given by the Spanish regulation (Eco toxic / non eco toxic) into clearly identifiable specific types of waste

Dynamics of electrochemical lithiation/delithiation of graphene-encapsulated silicon nanoparticles studied by in-situ TEM.

Science.gov (United States)

Luo, Langli; Wu, Jinsong; Luo, Jiayan; Huang, Jiaxing; Dravid, Vinayak P

2014-01-24

The incorporation of nanostructured carbon has been recently reported as an effective approach to improve the cycling stability when Si is used as high-capacity anodes for the next generation Li-ion battery. However, the mechanism of such notable improvement remains unclear. Herein, we report in-situ transmission electron microscopy (TEM) studies to directly observe the dynamic electrochemical lithiation/delithiation processes of crumpled graphene-encapsulated Si nanoparticles to understand their physical and chemical transformations. Unexpectedly, in the first lithiation process, crystalline Si nanoparticles undergo an isotropic to anisotropic transition, which is not observed in pure crystalline and amorphous Si nanoparticles. Such a surprising phenomenon arises from the uniformly distributed localized voltage around the Si nanoparticles due to the highly conductive graphene sheets. It is observed that the intimate contact between graphene and Si is maintained during volume expansion/contraction. Electrochemical sintering process where small Si nanoparticles react and merge together to form large agglomerates following spikes in localized electric current is another problem for batteries. In-situ TEM shows that graphene sheets help maintain the capacity even in the course of electrochemical sintering. Such in-situ TEM observations provide valuable phenomenological insights into electrochemical phenomena, which may help optimize the configuration for further improved performance.

Characterisation of silica surfaces III: Characterisation of aerosil samples through ethanol adsorption and contact angle studies

Directory of Open Access Journals (Sweden)

M.S. Nadiye–Tabbiruka

2009-12-01

Full Text Available Aerosil samples, heat treated and then silylated with various silanes at various temperatures have been characterised by adsorption of ethanol at 293 K. Adsorption isotherms were plotted and the BET specific surface areas were determined. Contact angles were measured by the captive bubble method at the three phase contact line in ethanol, on glass slides similarly modified. Silylation was found to alter the ethanol adsorptive properties on aerosil and increase the contact angles on the glass slides to extents that depend on the silane used as well as the concentration of residual silanols and that of surface silyl groups.

Kinetic study on electrochemical oxidation of catechols in the ...

Indian Academy of Sciences (India)

glassy carbon electrode in different experimental conditions. The electrogenerated ... cancer activities.5 Catechols can be easily oxidized electrochemically to ... from unity and approaches to zero in basic solution. This behavior is related to the ...

Study of chemical and electrochemical properties of some elements in molten NaAlCl

International Nuclear Information System (INIS)

Bermond, Alain

1976-01-01

We describe a study of the electrochemical and chemical properties in molten mixtures of Aluminium Chloride-Sodium chloride, at 210 deg. C and the concept of acidity, related to chloride activity, is previously summarized. In a first part, the study of Mercury and Cadmium by means of electro-analytical techniques, states the Hg 2+ 2 , Hg 2+ , Cd 2+ 2 and Cd 2+ ions and their acid properties. Some diagrams Equilibrium potential vs acidity are the synthesis of these results. In a second part, it is shown that a nickel electrode is an indicator of the presence of oxide ions; from interpretation of electrochemical results, O 2 appears to behave, in terms of the chloro-acido-basicity concept, as a strong di-base, giving the solvated form AlOCl - 2 , or a strong tri-base giving AlOCl. A saturation effect by Al 2 O 3 appears when the oxide concentration is increased; the solubility of Al 2 O 3 versus acidity is determined from the electrochemical results. In a third part, results for the Ni/Ni(II) or HCl/H 2 O systems are related to dissolved oxide ion presence in chloroaluminate melts; elimination of oxide ions, through H 2 O formation, by reaction with HCl is noteworthy. (author) [fr

Characterisation

Science.gov (United States)

2007-03-01

Characterisation. In Nanotechnology Aerospace Applications – 2006 (pp. 4-1 – 4-8). Educational Notes RTO-EN-AVT-129bis, Paper 4. Neuilly-sur-Seine, France: RTO...the Commercialisation Processes Concept IDEA Proof-of- Principle Trial Samples Engineering Verification Samples Design Verification Samples...SEIC Systems Engineering for commercialisation Design Houses, Engineering & R&D USERS & Integrators SE S U R Integrators Fabs & Wafer Processing Die

Electrochemical study of lithium insertion into carbon-rich polymer-derived silicon carbonitride ceramics

International Nuclear Information System (INIS)

Kaspar, Jan; Mera, Gabriela; Nowak, Andrzej P.; Graczyk-Zajac, Magdalena; Riedel, Ralf

2010-01-01

This paper presents the lithium insertion into carbon-rich polymer-derived silicon carbonitride (SiCN) ceramic synthesized by the thermal treatment of poly(diphenylsilylcarbodiimide) at three temperatures, namely 1100, 1300, and 1700 o C under 0.1 MPa Ar atmosphere. At lower synthesis temperatures, the material is X-ray amorphous, while at 1700 o C, the SiCN ceramic partially crystallizes. Anode materials prepared from these carbon-rich SiCN ceramics without any fillers and conducting additives were characterized using cyclic voltammetry and chronopotentiometric charging/discharging. We found that the studied silicon carbonitride ceramics demonstrate a promising electrochemical behavior during lithium insertion/extraction in terms of capacity and cycling stability. The sample synthesized at 1300 o C exhibits a reversible capacity of 392 mAh g -1 . Our study confirms that carbon-rich SiCN phases are electrochemically active materials in terms of Li inter- and deintercalation.

Electrochemical analysis

International Nuclear Information System (INIS)

Hwang, Hun

2007-02-01

This book explains potentiometry, voltametry, amperometry and basic conception of conductometry with eleven chapters. It gives the specific descriptions on electrochemical cell and its mode, basic conception of electrochemical analysis on oxidation-reduction reaction, standard electrode potential, formal potential, faradaic current and faradaic process, mass transfer and overvoltage, potentiometry and indirect potentiometry, polarography with TAST, normal pulse and deferential pulse, voltammetry, conductometry and conductometric titration.

Service water electrochemical monitoring development at Ontario Hydro

International Nuclear Information System (INIS)

Brennenstuhl, A.M.

1994-01-01

Ontario Hydro (OH) is currently investigating the feasibility of using electrochemical techniques for the corrosion monitoring of service water systems. To date all evaluations have been carried out in a field simulator. The studies include examining the effects of; system startup after periods of stagnation, sodium hypochlorite injection, and zebra mussel settlement on metallic surfaces. Carbon steel and Type 304L stainless steel have been evaluated. Electrochemical potential noise (EPN), electrochemical current noise (ECN) potential and coupling current were semi-continuously monitored over a period of up to one year. Data obtained from the electrochemical noise monitoring has given OH valuable insights into the mechanisms of degradation in service water systems. The high sensitivity of the electrochemical noise technique, particularly to localized corrosion has proved to be the major attraction of the system

Electrochemical Promotion of Catalytic Reactions Using

DEFF Research Database (Denmark)

Petrushina, Irina; Bjerrum, Niels; Cleemann, Lars Nilausen

2007-01-01

This paper presents the results of a study on electrochemical promotion (EP) of catalytic reactions using Pt/C/polybenzimidazole(H3PO4)/Pt/C fuel cell performed by the Energy and Materials Science Group (Technical University of Denmark) during the last 6 years[1-4]. The development of our...... understanding of the nature of the electrochemical promotion is also presented....

The study of optimal conditions of electrochemical etching of tunnel electron microscopy tungsten tips

International Nuclear Information System (INIS)

Anguiano, E.; Aguilar, M.; Olivar, A.I.

1996-01-01

We present the experimental results obtained during the study made in the electrochemical etching of tunneling electron microscopy tungsten tips. The experiments was made using DC and two usual electrolytes: KOH and NaOH. For the tip preparation we used a electrochemical cell with stainless steel cathode and the tungsten wire as anode. the electrodes was introduced in a glass recipient containing the electrolytic solution. We study the effects of applied voltage, polish time, tip length and electrolyte concentration as process relevant parameters. The best condition for tip preparation was obtained with a metallurgical microscope and with a SEM.EDX and Auger analysis was made. The results shown the better tips was made with KOH as electrolyte with a limited concentration range (2-4 normal) and applied voltage (2-6 volts) (Author) 20 refs

Building micro and nanosystems with electrochemical discharges

International Nuclear Information System (INIS)

Wuethrich, Rolf; Allagui, Anis

2010-01-01

Since the discovery of the electrochemical discharge phenomenon by Fizeau and Foucault, several contributions have expanded the wide range of applications associated with this high current density electrochemical process. The complexity of the phenomenon, from the macroscopic to the microscopic scales, led since then to experimental and theoretical studies from different research fields. This contribution reviews the chemical and electrochemical perspectives where a mechanistic model based on results from radiation chemistry of aqueous solutions is proposed. In addition applications to micro-machining and fabrication of nanoparticles are discussed.

Building micro and nanosystems with electrochemical discharges

Energy Technology Data Exchange (ETDEWEB)

Wuethrich, Rolf, E-mail: wuthrich@encs.concordia.c [Department of Mechanical and Industrial Engineering, Concordia University, 1455 de Maisonneuve Blvd. West, Montreal, QC (Canada); Allagui, Anis [Department of Mechanical and Industrial Engineering, Concordia University, 1455 de Maisonneuve Blvd. West, Montreal, QC (Canada)

2010-11-30

Since the discovery of the electrochemical discharge phenomenon by Fizeau and Foucault, several contributions have expanded the wide range of applications associated with this high current density electrochemical process. The complexity of the phenomenon, from the macroscopic to the microscopic scales, led since then to experimental and theoretical studies from different research fields. This contribution reviews the chemical and electrochemical perspectives where a mechanistic model based on results from radiation chemistry of aqueous solutions is proposed. In addition applications to micro-machining and fabrication of nanoparticles are discussed.

Hydrogen storage material, electrochemically active material, electrochemical cell and electronic equipment

NARCIS (Netherlands)

2008-01-01

The invention relates to a hydrogen storage material comprising an alloy of magnesium. The invention further relates to an electrochemically active material and an electrochemical cell provided with at least one electrode comprising such a hydrogen storage material. Also, the invention relates to

Electrochemical Study of Hydrocarbon-Derived Electrolytes for Supercapacitors

Science.gov (United States)

Noorden, Zulkarnain A.; Matsumoto, Satoshi

2013-10-01

In this paper, we evaluate the essential electrochemical properties - capacitive and resistive behaviors - of hydrocarbon-derived electrolytes for supercapacitor application using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrolytes were systematically prepared from three hydrocarbon-derived compounds, which have different molecular structures and functional groups, by treatment with high-concentration sulfuric acid (H2SO4) at room temperature. Two-electrode cells were assembled by sandwiching an electrolyte-containing glass wool separator with two active electrodes of activated carbon sheets. The dc electrical properties of the tested cells in terms of their capacitive behavior were investigated by CV, and in order to observe the frequency characteristics of the constructed cells, EIS was carried out. Compared with the tested cell with only high-concentration H2SO4 as the electrolyte, the cell with the derived electrolytes exhibit a capacitance as high as 135 F/g with an improved overall internal resistance of 2.5 Ω. Through the use of a simple preparation method and low-cost precursors, hydrocarbon-derived electrolytes could potentially find large-scale and higher-rating supercapacitor applications.

Electrochemical and DFT study of an anticancer and active anthelmintic drug at carbon nanostructured modified electrode.

Science.gov (United States)

Ghalkhani, Masoumeh; Beheshtian, Javad; Salehi, Maryam

2016-12-01

The electrochemical response of mebendazole (Meb), an anticancer and effective anthelmintic drug, was investigated using two different carbon nanostructured modified glassy carbon electrodes (GCE). Although, compared to unmodified GCE, both prepared modified electrodes improved the voltammetric response of Meb, the carbon nanotubes (CNTs) modified GCE showed higher sensitivity and stability. Therefore, the CNTs-GCE was chosen as a promising candidate for the further studies. At first, the electrochemical behavior of Meb was studied by cyclic voltammetry and differential pulse and square wave voltammetry. A one step reversible, pH-dependent and adsorption-controlled process was revealed for electro-oxidation of Meb. A possible mechanism for the electrochemical oxidation of Meb was proposed. In addition, electronic structure, adsorption energy, band gap, type of interaction and stable configuration of Meb on the surface of functionalized carbon nanotubes were studied by using density functional theory (DFT). Obtained results revealed that Meb is weakly physisorbed on the CNTs and that the electronic properties of the CNTs are not significantly changed. Notably, CNTs could be considered as a suitable modifier for preparation of the modified electrode for Meb analysis. Then, the experimental parameters affecting the electrochemical response of Meb were optimized. Under optimal conditions, high sensitivity (b(Meb)=dIp,a(Meb)/d[Meb]=19.65μAμM(-1)), a low detection limit (LOD (Meb)=19nM) and a wide linear dynamic range (0.06-3μM) was resulted for the voltammetric quantification of Meb. Copyright © 2016 Elsevier B.V. All rights reserved.

Graphene-Paper Based Electrochemical Sensors

DEFF Research Database (Denmark)

Zhang, Minwei; Halder, Arnab; Cao, Xianyi

2017-01-01

in electrochemical sensors and energy technologies amongothers. In this chapter, we present some examples to overview recent advances in theresearch and development of two-dimensional (2D) graphene papers as new materialsfor electrochemical sensors. The chapter covers the design, fabrication, functionalizationand...... functionalization ofgraphene papers with polymer and nanoscale functional building blocks for electrochemical-sensing purposes. In terms of electrochemical-sensing applications, the emphasis ison enzyme-graphene and nanoparticle-graphene paper-based systems for the detectionof glucose. We finally conclude...

Corrosion behaviour of Ni in aprotic solvents an electrochemical, XPS and AFM study

International Nuclear Information System (INIS)

Bellucci, F.; Monetta, T.; Capobianco, G.; Deganello, A.; Glisenti, A.; Moretti, G.

1998-01-01

Electrochemical and X-ray photoelectron spectroscopic (XPS) techniques have been used to study the passivation of nickel in 0.1 M H 2 SO 4 DMF and ACN solutions with different water content. Electrochemical results indicate the anodic formation of a thin, poor protective layer and the possibility of salt precipitation onto the metallic surface. ARXPS results indicate that while in the anodic film formed in DMF, Ni(OH) 2 constitute the superficial component under which a discontinuous layer of NiO and NiSO 4 is present. Ni(OH) 2 and NiSO 4 are the more superficial constituents in the passivation layer formed in ACN, while NiO becomes prevalent in the underlying layers. AFM images show that in both the solvents the sample surface is very dishomogeneous with flakes and fractures. (orig.)

Defect studies of ZnO single crystals electrochemically doped with hydrogen

Science.gov (United States)

Čížek, J.; Žaludová, N.; Vlach, M.; Daniš, S.; Kuriplach, J.; Procházka, I.; Brauer, G.; Anwand, W.; Grambole, D.; Skorupa, W.; Gemma, R.; Kirchheim, R.; Pundt, A.

2008-03-01

Various defect studies of hydrothermally grown (0001) oriented ZnO crystals electrochemically doped with hydrogen are presented. The hydrogen content in the crystals is determined by nuclear reaction analysis and it is found that already 0.3at.% H exists in chemically bound form in the virgin ZnO crystals. A single positron lifetime of 182ps is detected in the virgin crystals and attributed to saturated positron trapping at Zn vacancies surrounded by hydrogen atoms. It is demonstrated that a very high amount of hydrogen (up to ˜30at.%) can be introduced into the crystals by electrochemical doping. More than half of this amount is chemically bound, i.e., incorporated into the ZnO crystal lattice. This drastic increase of the hydrogen concentration is of marginal impact on the measured positron lifetime, whereas a contribution of positrons annihilated by electrons belonging to O-H bonds formed in the hydrogen doped crystal is found in coincidence Doppler broadening spectra. The formation of hexagonal shape pyramids on the surface of the hydrogen doped crystals by optical microscopy is observed and discussed.

Study and optimisation of manganese oxide-based electrodes for electrochemical supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Staiti, P.; Lufrano, F. [CNR-ITAE, Istituto di Tecnologie Avanzate per l' Energia ' ' Nicola Giordano' ' , Via Salita S. Lucia n. 5, 98126 S. Lucia, Messina (Italy)

2009-02-01

A manganese oxide material was synthesised by an easy precipitation method based on reduction of potassium permanganate(VII) with a manganese(II) salt. The material was treated at different temperatures to study the effect of thermal treatment on capacitive property. The best capacitive performance was obtained with the material treated at 200 C. This material was used to prepare electrodes with different amounts of polymer binder, carbon black and graphite fibres to individuate the optimal composition that gave the best electrochemical performances. It was found that graphite fibres improve the electrochemical performance of electrodes. The highest specific capacitance (267 F g{sup -1} MnO{sub x}) was obtained with an electrode containing 70% of MnO{sub x}, 15% of carbon black, 10% of graphite fibres and 5% of PVDF. This electrode, with CB/GF ratio of 1.5, showed a higher utilization of manganese oxide. The results reported in the present paper further confirmed that manganese oxide is a very interesting material for supercapacitor application. (author)

Characterisation of long-lived low and intermediate-level radioactive wastes in the Nordic Countries

International Nuclear Information System (INIS)

Broden, K.; Carugati, S.; Brodersen, K.; Carlsson, T.; Viitanen, P.; Walderhaug, T.; Sneve, M.; Hornkjoel, S.; Backe, S.

1997-11-01

The present report is final report from a study on characterisation of radioactive waters in the Nordic countries. The study has mainly been focused on long-lived low and intermediate level radioactive waste. Methods to measure or estimate the activity content and the general composition are discussed. Recommendations are given regarding characterisation of waste under treatment and characterisation of already produced waste packages. (au)

Characterisation of long-lived low and intermediate-level radioactive wastes in the Nordic Countries

Energy Technology Data Exchange (ETDEWEB)

Broden, K. [Studsvik RadWaste AB, (El Salvador); Carugati, S.; Brodersen, K. [Forskningscenter Risoe, (Denmark); Carlsson, T.; Viitanen, P. [VVT, (Finland); Walderhaug, T. [Icelandic Radiation Protection Institute (Iceland); Sneve, M.; Hornkjoel, S. [Norwegian Radiation Protection Authority (Norway); Backe, S. [Institute for Energy Technology (Norway)

1997-11-01

The present report is final report from a study on characterisation of radioactive waters in the Nordic countries. The study has mainly been focused on long-lived low and intermediate level radioactive waste. Methods to measure or estimate the activity content and the general composition are discussed. Recommendations are given regarding characterisation of waste under treatment and characterisation of already produced waste packages. (au).

Radiological Characterisation from a Waste and Materials End-State Perspective: Practices and Experience

International Nuclear Information System (INIS)

Mommaert, Chantal; Andrieu, Caroline; Desnoyers, Yvon; Denis Pombet; Salsac, Marie-Delphine; Knaack, Michael; Altavilla, Massimo; Manes, Daniela; Takahashi, Hiroaki; Ul Syed, Naeem; Palomo, Nieves Martin; Larsson, Arne; Dunlop, Alister; Susan Brown; Emptage, Matthew; Black, Greg; Abu-Eid, Rateb; Szilagyi, Andrew; Weber, Inge; )

2017-01-01

Radiological characterisation is a key enabling activity for the planning and implementation of nuclear facility decommissioning. Effective characterisation allows the extent, location and nature of contamination to be determined and provides crucial information for facility dismantling, the management of material and waste arisings, the protection of workers, the public and the environment, and associated cost estimations. This report will be useful for characterisation practitioners who carry out tactical planning, preparation, optimisation and implementation of characterisation to support the decommissioning of nuclear facilities and the management of associated materials and waste. It compiles recent experience from NEA member countries in radiological characterisation, including from international experts, international case studies, an international conference, and international standards and guidance. Using this comprehensive evidence base, the report identifies relevant good practice and provides practical advice covering all stages of the characterisation process

Study on electrochemical corrosion mechanism of steel foot of insulators for HVDC lines

Science.gov (United States)

Zheng, Weihua; Sun, Xiaoyu; Fan, Youping

2017-09-01

The main content of this paper is the mechanism of electrochemical corrosion of insulator steel foot in HVDC transmission line, and summarizes five commonly used artificial electrochemical corrosion accelerated test methods in the world. Various methods are analyzed and compared, and the simulation test of electrochemical corrosion of insulator steel feet is carried out by water jet method. The experimental results show that the experimental environment simulated by water jet method is close to the real environment. And the three suspension modes of insulators in the actual operation, the most serious corrosion of the V type suspension hardware, followed by the tension string suspension, and the linear string corrosion rate is the slowest.

Electrochemical reduction of NO{sub x}

Energy Technology Data Exchange (ETDEWEB)

Lund Traulsen, M.

2012-04-15

NO and NO{sub 2} (collectively referred to as NO{sub x}) are air pollutants, and the largest single contributor to NO{sub x} pollution is automotive exhaust. This study investigates electrochemical deNO{sub x}, a technology which aims to remove NO{sub x} from automotive diesel exhaust by electrochemical reduction of NO{sub x} to N{sub 2} and O{sub 2}. The focus in this study is on improving the activity and selectivity of solid oxide electrodes for electrochemical deNO{sub x} by addition of NO{sub x} storage compounds to the electrodes. Two different composite electrodes, La{sub 0.85}Sr{sub 0.15}MnO{sub 3-{delta}-}Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} (LSM15-CGO10) and La{sub 0.85}Sr{sub 0.15}FeO{sub 3-{delta}-}Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} (LSF15-CGO10), have been investigated in combination with three different NO{sub x} storage compounds: BaO, K{sub 2}O and MnO{sub x}. The main focus in the investigation has been on conversion measurements and electrochemical characterization, the latter by means of electrochemical impedance spectroscopy and cyclic voltammetry. In addition, infrared spectroscopy has been performed to study how NO{sub x} adsorption on the electrodes is affected by the presence of the aforementioned NO{sub x} storage compounds. Furthermore, non-tested and tested electrode microstructures have been thoroughly evaluated by scanning electron microscopy. The studies reveal addition of MnO{sub x} or K{sub 2}O to the electrodes cause severe degradation problems, and addition of these compounds is thus unsuitable for electrode improvement. In contrast, addition of BaO to LSM15-CGO10 electrodes is shown to have a very positive impact on the NO{sub x} conversion. The increased NO{sub x} conversion, following the BaO addition, is attributed to a combination of 1) a decreased electrode polarisation resistance and 2) an altered NO{sub x} adsorption. The NO{sub x} conversion is observed to increase strongly with polarisation, and during 9 V polarisation of an

ELECTROCHEMICAL OXIDATION OF ETHANOL USING Ni-Co-PVC COMPOSITE ELECTRODE

Directory of Open Access Journals (Sweden)

Riyanto Riyanto

2011-07-01

Full Text Available The morphological characteristics and electrochemical behavior of nickel metal foil (Ni, nickel-polyvinyl chloride (Ni-PVC and nickel-cobalt-polyvinyl chloride (Ni-Co-PVC electrodes in alkaline solution has been investigated. The morphological characteristics of the electrode surface were studied using SEM and EDS, while the electrochemical behavior of the electrodes was studied using cyclic voltammetry (CV. It was found that composite electrodes (Ni-PVC and Ni-Co-PVC have a porous, irregular and rough surface. In situ studies using electrochemical technique using those three electrodes exhibited electrochemical activity for redox system, as well as selectivity in the electrooxidation of ethanol to acetic acid. The studies also found that an electrokinetics and electrocatalytic activity behaviors of the electrodes prepared were Ni metal foil

A study of the electrochemical behaviour of electrodes in operating solid-state supercapacitors

International Nuclear Information System (INIS)

Staiti, P.; Lufrano, F.

2007-01-01

The electrochemical behaviour of electrodes and of complete solid-state supercapacitors has been studied by cyclic voltammetry (CV) and galvanostatic charge/discharge (CD) measurements using two independent electrochemical equipments. The first one controlled the execution of the test and recorded the voltage and current values of the complete supercapacitor while the other one recorded the potential changes of the single electrodes. In this work, two different types of capacitors were studied: (a) a symmetric supercapacitor using carbon electrodes, and (b) a hybrid (asymmetric) supercapacitor with ruthenium oxide/carbon in the positive electrode and carbon in the negative electrode. The studies evidenced that in the symmetric capacitors the positive electrode controlled the capacitive performance and an optimal mass ratio from 1.2:1 to 1.3:1 between the positive and the negative electrodes was found in the investigated conditions. For the hybrid supercapacitor it was observed that the ruthenium-based positive electrode influenced the capacitive performance of carbon-based negative electrode and that an accurate balance of carbon loading in the negative electrode was necessary

Electrochemical force microscopy

Energy Technology Data Exchange (ETDEWEB)

Kalinin, Sergei V.; Jesse, Stephen; Collins, Liam F.; Rodriguez, Brian J.

2017-01-10

A system and method for electrochemical force microscopy are provided. The system and method are based on a multidimensional detection scheme that is sensitive to forces experienced by a biased electrode in a solution. The multidimensional approach allows separation of fast processes, such as double layer charging, and charge relaxation, and slow processes, such as diffusion and faradaic reactions, as well as capturing the bias dependence of the response. The time-resolved and bias measurements can also allow probing both linear (small bias range) and non-linear (large bias range) electrochemical regimes and potentially the de-convolution of charge dynamics and diffusion processes from steric effects and electrochemical reactivity.

The Heroic and the Villainous: a qualitative study characterising the role models that shaped senior doctors' professional identity.

Science.gov (United States)

Foster, Kirsty; Roberts, Chris

2016-08-16

The successful development and sustaining of professional identity is critical to being a successful doctor. This study explores the enduring impact of significant early role models on the professional identity formation of senior doctors. Personal Interview Narratives were derived from the stories told by twelve senior doctors as they recalled accounts of people and events from the past that shaped their notions of being a doctor. Narrative inquiry methodology was used to explore and analyse video recording and transcript data from interviews. Role models were frequently characterised as heroic, or villainous depending on whether they were perceived as good or bad influences respectively. The degree of sophistication in participants' characterisations appeared to correspond with the stage of life of the participant at the time of the encounter. Heroes were characterised as attractive, altruistic, caring and clever, often in exaggerated terms. Conversely, villains were typically characterised as direct or covert bullies. Everyday events were surprisingly powerful, emotionally charged and persisted in participants' memories much longer than expected. In particular, unresolved emotions dating from encounters where bullying behaviour had been witnessed or experienced were still apparent decades after the event. The characterisation of role models is an important part of the professional identity and socialisation of senior doctors. The enduring impact of what role models say and do means that all doctors, need to consistently reflect on how their own behaviour impacts the development of appropriate professional behaviours in both students and training doctors. This is especially important where problematic behaviours occur as, if not dealt with, they have the potential for long-lasting undesirable effects. The importance of small acts of caring in building a nurturing and supportive learning atmosphere at all stages of medical education cannot be underestimated.

Optical and electrochemical studies of polyaniline/SnO{sub 2} fibrous nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Manivel, P. [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Ramakrishnan, S.; Kothurkar, Nikhil K. [Department of Chemical Engineering and Material Science, Amrita Vishwa Vidyapeetham, Coimbatore 641 112, Tamil Nadu (India); Balamurugan, A.; Ponpandian, N.; Mangalaraj, D. [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Viswanathan, C., E-mail: viswanathan@buc.edu.in [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India)

2013-02-15

Graphical abstract: Fiber with porous like structure of PANI/SnO{sub 2} nanocomposites were prepared by simplest in situ chemical polymerization method. The PL emission spectra revealed that the band from 404 and 436 nm which is related with oxygen vacancies. The excellent electrochemical properties of composite electrode show the specific capacitance of 173 F/g at a scan rate of 25 m V/s. Display Omitted Highlights: ► Self assembled PANI/SnO{sub 2} nanocomposites were synthesized by simple polymerization method. ► Electrochemical behavior of PANI/SnO{sub 2} nanocomposites electrode was analyzed by CV. ► Nanocomposites exhibit a higher specific capacitance of 173 F/g, compared with pure SnO{sub 2}. -- Abstract: Polyaniline (PANI)/tin oxide (SnO{sub 2}) fibrous nanocomposites were successfully prepared by an in situ chemical polymerization method with suitable conditions. The obtained composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, photoluminescence (PL), electrical conductivity and cyclic voltammetry studies (CV). The XRD pattern of the as-prepared sample shows the presence of tetragonal SnO{sub 2} and the crystalline structure of SnO{sub 2} was not affected with the incorporation of PANI. The FTIR analysis confirms the uniform attachment of PANI on the surface of SnO{sub 2} nanostructures. SEM images show a fibrous agglomerated structure of PANI/SnO{sub 2}. The PL emission spectra revealed that the band from 404 and 436 nm which is related with oxygen vacancies. The electrochemical behavior of the PANI/SnO{sub 2} composite electrode was evaluated in a H{sub 2}SO{sub 4} solution using cyclic voltammetry. The composite electrode exhibited a specific capacitance of 173 F/g at a scan rate 25 mV/s. Thus the as-prepared PANI/SnO{sub 2} composite shows excellent electrochemical properties, suggesting that this composite is a promising material for supercapacitors.

Electrochemical behaviour of carbon paste electrodes enriched with tin oxide nanoparticles using voltammetry and electrochemical impedance spectroscopy.

Science.gov (United States)

Muti, Mihrican; Erdem, Arzum; Caliskan, Ayfer; Sınag, Ali; Yumak, Tugrul

2011-08-01

The effect of the SnO(2) nanoparticles (SNPs) on the behaviour of voltammetric carbon paste electrodes were studied for possible use of this material in biosensor development. The electrochemical behaviour of SNP modified carbon paste electrodes (CPE) was first investigated by using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The performance of the SNP modified electrodes were compared to those of unmodified ones and the parameters affecting the response of the modified electrode were optimized. The SNP modified electrodes were then tested for the electrochemical sensing of DNA purine base adenine to explore their further development in biosensor applications. Copyright © 2011 Elsevier B.V. All rights reserved.

SiteChar. Characterisation of European CO2 storage. Deliverable D8.1. Qualitative and quantitative social site characterisations

Energy Technology Data Exchange (ETDEWEB)

Brunsting, S.; Pol, M.; Paukovic, M. [ECN Policy Studies, Energy research Centre of the Netherlands ECN, Amsterdam (Netherlands); Kaiser, M.; Zimmer, R. [Unabhaengiges Institut fuer Umweltfragen UfU, Berlin (Germany); Shackley, S.; Mabon, L. [Scottish Carbon Capture and Storage SCCS, Edinburg, Scotland (United Kingdom); Hepplewhite, F.; Loveridge, R. [Energy Markets Unit, Scottish Government, Edinburg, Scotland (United Kingdom); Mazurowski, M.; Polak-Osiniak, D. [Polish Oil and Gas Company PGNiG, Warszawa (Poland); Rybicki, C. [AGH University of Science and Technology, Krakow (Poland)

2012-10-15

At local level, public support has proven crucial to the implementation of CO2 capture and storage (CCS) demonstration projects. Whereas no method exists to guarantee public acceptability of any project, a constructive stakeholder engagement process does increase the likelihood thereof. Social site characterisation can be used as an instrument to explore, plan and evaluate a process of active and constructive local stakeholder engagement in a prospective CCS project as a parallel activity to technical site characterisation. It roughly consists of a formative research phase to get acquainted with the area followed by a series of public information and engagement activities. This deliverable presents results from the first phase for the social site characterisations of a prospective CCS site in Poland (onshore) and the UK (offshore), using qualitative as well as quantitative research methods, as a first step to planning of local public engagement activities and evaluation of these activities that will be undertaken by this consortium at both sites in the near future. Although the term social site characterisation actually refers to the entire process of formative research and subsequent public outreach, and hence to the complete package of awareness work undertaken as part of SiteChar, in the present deliverable the term only refers to the formative research activities as undertaken up to now and as described in this deliverable. The qualitative part of the social site characterisation consisted of (1) a description of relevant social site characteristics such as local history; (2) interviews with relevant local stakeholders; (3) a media analysis of local newspapers. The quantitative part of the social site characterisation consisted of surveys using representative samples to characterise the local population in terms of awareness, knowledge and perceptions of CCS, felt involvement in decision making, extent of local activism, level of trust in representatives and

Numerical Study of the Buoyancy-Driven Flow in a Four-Electrode Rectangular Electrochemical Cell

Science.gov (United States)

Sun, Zhanyu; Agafonov, Vadim; Rice, Catherine; Bindler, Jacob

2009-11-01

Two-dimensional numerical simulation is done on the buoyancy-driven flow in a four-electrode rectangular electrochemical cell. Two kinds of electrode layouts, the anode-cathode-cathode-anode (ACCA) and the cathode-anode-anode-cathode (CAAC) layouts, are studied. In the ACCA layout, the two anodes are placed close to the channel outlets while the two cathodes are located between the two anodes. The CAAC layout can be converted from the ACCA layout by applying higher electric potential on the two middle electrodes. Density gradient was generated by the electrodic reaction I3^-+2e^- =3I^-. When the electrochemical cell is accelerated axially, buoyancy-driven flow occurs. In our model, electro-neutrality is assumed except at the electrodes. The Navier-Stokes equations with the Boussinesq approximation and the Nernst-Planck equations are employed to model the momentum and mass transports, respectively. It is found that under a given axial acceleration, the electrolyte density between the two middle electrodes determines the bulk flow through the electrochemical cell. The cathodic current difference is found to be able to measure the applied acceleration. Other important electro-hydrodynamic characteristics are also discussed.

The Electrochemical Behavior of SnSb as an Anode for Li-ion Batteries Studied by Electrochemical Impedance Spectroscopy and Electron Microscopy

International Nuclear Information System (INIS)

Tesfaye, Alexander T.; Yücel, Yasemin D.; Barr, Maïssa K.S.; Santinacci, Lionel; Vacandio, Florence; Dumur, Frédéric; Maria, Sébastien; Monconduit, Laure; Djenizian, Thierry

2017-01-01

Highlights: •Electrochemical behavior of SnSb is investigated by EIS, SEM and TEM. •Formation of SEI and cracks occurs during cycling experiments. •The capacity fading as a result of the electrode modifications is discussed. -- Abstract: Evolution of the electrical and morphological properties of micron-sized SnSb has been investigated to understand the electrochemical behavior observed during cycling experiments. Electron microscopy techniques (scanning electron microscopy and transmission electron microscopy) and electrochemical impedance spectroscopy have been combined to evidence the electrode modifications and particularly the formation of a solid electrolyte interphase (SEI) layer. Evolution of the SEI resistance and the charge transfer resistance with the cell voltage can be explained by the electrolyte degradation and expansion/contraction of the electrode. Furthermore, we show that the SEI formation is not limited at the first discharge/charge of the battery. The continuous growth of the SEI layer up to 50 cycles associated to the electrode pulverization caused by the large volume variations are responsible for the capacity fading.

Chemical Production of Graphene Catalysts for Electrochemical Energy Conversion

DEFF Research Database (Denmark)

Seselj, Nedjeljko

by scanning tunneling microscopy (STM), to investigate the nature of L-cysteine bonds on Au. Synthesized electrocatalysts were characterized by spectroscopic, microscopic and electrochemical techniques. Electrocatalysis was examined by electrochemical oxidation of formic acid, methanol and ethanol, and oxygen......Recently developed FC technology is among many approaches aiming at solving the global energy challenges. FCs are electrochemical devices that convert chemical energy from fuel molecules into electrical energy via electrochemical reactions. FCs are, however, limited by the scarce and expensive...... was achieved via L-cysteine linker molecules that provided pathways for fast electron transfers during the electrocatalytic reactions. Electrochemical properties of selfassembled L-cysteine monolayers immobilized on single-crystal Au(111) surfaces were studied in ionic liquids and their structures imaged...

Electrochemical Study of Welded AISI 304 and 904L Stainless Steel in Seawater in View of Corrosion

Directory of Open Access Journals (Sweden)

Richárd Székely

2010-10-01

Full Text Available This is a comparative study of the corrosion behaviour of welds in AISI 304 and AISI 904L stainless steels carried out in seawater model solution in the temperature range 5-35°C and the standard of corrosion testing of welds was followed. The corrosion rate and corrosion attack characteristics were determined for welds of the examined steels with several type of treatment. The aim of this work was to compare the steels based on their resistance against the corrosion in terms of pitting potential (Epit and repassivation potential (Erepass. Seawater is an electrochemically aggressive medium, which can initiate localised corrosion in welded stainless steels. Different electrochemical and testing methods were used, including cyclic voltammetry, chronopotentiometry, electrochemical impedance spectroscopy (EIS, pH measuring and penetration tests.

Electrochemical and conversion electron Moessbauer study of corrosion induced by acid rain

International Nuclear Information System (INIS)

Vertes, C.; Lakatos-Varsanyi, M.; Vertes, A.; Meisel, W.; Guetlich, P.

1993-01-01

The passivation of low carbon steel was studied in aqueous solution of 0.5M Na 2 SO 4 +0.001M NaHSO 3 (pH 3.5, 6.5 and 8.5) which can be considered as a model of acid rain. The used conversion electron Moessbauer spectroscopy (CEMS) with the complementary electrochemical investigations proved that the sulfite ions induce pitting corrosion at pH 3.5 and 6.5, while the measurements showed much weaker pitting at pH 8.5. The compositions and thicknesses of the passive films formed during the electrochemical treatments are determined from the CEM spectra. Only γ-FeOOH was found on the surface of the samples at pH 6.5 and 8.5. Nevertheless, at pH 3.5 the sextet belonging to Fe 3 C appears in the spectra, and also FeSO 4 .H 2 O could be detected in low concentration. (orig.)

Synergy of Nyquist and Bode electrochemical impedance spectroscopy studies to particle size effect on the electrochemical properties of LiNi0.5Co0.2Mn0.3O2

International Nuclear Information System (INIS)

Liang, Chenghao; Liu, Lianbao; Jia, Zheng; Dai, Changsong; Xiong, Yueping

2015-01-01

To study the mechanism of material particle size effects on the electrochemical properties of LiNi 0.5 Co 0.2 Mn 0.3 O 2 , two kinds of materials with particle size of 300 nm and 1 μm were prepared, based on the electrospinning method and sol-gel method, respectively. The capacity differences of the two materials at 20 mA/g discharge current were unapparent, in the potential range of 2.8V–4.3 V, but become gigantic at 1000 mA/g discharge current. Electrochemical impedance spectroscopy (EIS) was employed to analysis the differences caused by particle size, and frequency responses of every electrochemical process were analyzed in detail through Bode plots, which proved the electrospinning material had an excellent performance caused by a shorter lithium ion and electron diffusion distance.

Electrochemical study in molten sodium fluoroborate at 4200C

International Nuclear Information System (INIS)

Wagner, J.F.

1983-06-01

By analysing the behavior of the electrochemical system Cu (I)/Cu it was possible to study the acid-base properties of molten sodium fluoroborate. The anion of the solvent BF 4 - is shown to undergo a strong dissociation according to the equilibrium BF 4 - BF 3 (g) + F - , the Ki constant at 420 0 C being evaluated at 1.58 x 10 -2 mol kg -1 atm. The acidity variations of sodium fluoroborate at this temperature are limited to about two pF units (pKi=1.8). A potentiometric study of the copper, silver and nickel systems showed that the corresponding metallic cations are little complexed by fluoride ions in spite of the strong dissociation of the solvent [fr

Materials for electrochemical capacitors

Science.gov (United States)

Simon, Patrice; Gogotsi, Yury

2008-11-01

Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

Analytical Characterisation of Nanoscale Zero-Valent Iron: A ...

Science.gov (United States)

Zero-valent iron nanoparticles (nZVI) have been widely tested as they are showing significant promise for environmental remediation. However, many recent studies have demonstrated that their mobility and reactivity in subsurface environments are significantly affected by their tendency to aggregate. Both the mobility and reactivity of nZVI mainly depends on properties such as particle size, surface chemistry and bulk composition. In order to ensure efficient remediation, it is crucial to accurately assess and understand the implications of these properties before deploying these materials into contaminated environments. Many analytical techniques are now available to determine these parameters and this paper provides a critical review of their usefulness and limitations for nZVI characterisation. These analytical techniques include microscopy and light scattering techniques for the determination of particle size, size distribution and aggregation state, and X-ray techniques for the characterisation of surface chemistry and bulk composition. Example characterisation data derived from commercial nZVI materials is used to further illustrate method strengths and limitations. Finally, some important challenges with respect to the characterisation of nZVI in groundwater samples are discussed. In recent years, manufactured nanoparticles (MNPs) have attracted increasing interest for their potential applications in the treatment of contaminated soil and water. In compar

In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

International Nuclear Information System (INIS)

Bertram, F.; Evertsson, J.; Messing, M. E.; Mikkelsen, A.; Lundgren, E.; Zhang, F.; Pan, J.; Carlà, F.; Nilsson, J.-O.

2014-01-01

We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

Electrochemical study on the cationic promotion of the catalytic SO2 oxidation in pyrosulfate melts

DEFF Research Database (Denmark)

Petrushina, Irina; Bjerrum, Niels; Cappeln, Frederik Vilhelm

1998-01-01

The electrochemical behavior of the molten V2O5-M2S2O7 (M = K, Cs, or Na) system was studied using a gold working electrode at 440 degrees C in argon and air atmosphere. The aim of the present investigation was to find a possible correlation between the promoting effect of Cs+ and Na+ ions...... on the catalytic oxidation of SO2 in the V2O5-M2S2O7 system and the effect of these alkali cations on the electrochemical behavior of V2O5 in the alkali pyrosulfate melts It has been shown that Na+ ions had a promoting effect on the V(V) reversible arrow V(IV) electrochemical reaction. Sodium ions accelerate both...... in the catalytic SO, oxidation most likely is the oxidation of V(IV) to V(V) and the Na+ and Cs+ promoting effect is based on the acceleration of this stage. It has also been proposed that voltammetric measurements can be used for fast optimization of the composition of the vanadium catalyst (which...

Electrochemical stability of subnanometer Pt clusters

DEFF Research Database (Denmark)

Quinson, Jonathan; Röefzaad, Melanie; Deiana, Davide

2018-01-01

In the present work, the degradation of size-selected Pt nanoclusters is studied under electrochemical conditions. This model catalyst mimics carbon supported Pt nanoclusters and nanoparticles typically employed in proton exchange membrane fuel cells (PEMFCs). Insight into the early stage...... of degradation is given by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and confirmed by transmission electron microscopy (TEM). In contrast to common assumptions, it is demonstrated that even extremely small Pt clusters exhibit a remarkable stability under electrochemical...... - is observed. In light of the findings reported, developing highly-dispersed subnanometer Pt clusters as catalyst for PEMFCs is a realistic approach provided the operation conditions are suitably adjusted. Furthermore, mitigation strategies to improve the stability of few-atoms catalyst under electrochemical...

Diversity in electrochemical oxidation of dihydroxybenzenes in the ...

Indian Academy of Sciences (India)

Abstract. Electrochemical oxidation of some catechol derivatives (1a–e) have been studied in water/ acetonitrile solution containing 1-methylindole (3) as a nucleophile, using cyclic voltammetry and controlled- potential coulometry. An interesting diversity in the mechanisms has been observed in electrochemical oxidation ...

Electrochemical and spectroscopic characterisation of amphetamine-like drugs: Application to the screening of 3,4-methylenedioxymethamphetamine (MDMA) and its synthetic precursors

OpenAIRE

Milhazes, Nuno; Martins, Pedro; Uriarte, Eugenio; Garrido, Jorge; Calheiros, Rita; Marques, M. Paula M.; Borges, Fernanda

2007-01-01

A complete physicochemical characterisation of MDMA and its synthetic precursors MDA, 3,4-methylenedioxybenzaldehyde (piperonal) and 3,4-methylenedioxy-beta-methyl-beta-nitrostyrene was carried out through voltammetric assays and Raman spectroscopy combined with theoretical (DFT) calculations. The former provided important analytical redox data, concluding that the oxidative mechanism of the N-demethylation of MDMA involves the removal of an electron from the amino-nitrogen atom, leading to t...

Hydrodynamics studies of cyclic voltammetry for electrochemical micro biosensors

DEFF Research Database (Denmark)

Adesokan, Bolaji James; Quan, Xueling; Evgrafov, Anton

2015-01-01

We investigate the effect of flow rate on the electrical current response to the applied voltage in a micro electrochemical system. To accomplish this, we considered an ion-transport model that is governed by the Nernst-Planck equation coupled to the Navier-Stokes equations for hydrodynamics...

U_xTh_1_-_x(C_2O_4)_2 solide characterisation studies

International Nuclear Information System (INIS)

Carrigan, C.; Taylor, R.; Sarsfield, M.

2016-01-01

Many advanced reprocessing schemes under development are aimed at co-processing and co-conversion of actinides, unlike current reprocessing plants that produce separate uranium and plutonium products. The most well developed option for the co-conversion stage is probably oxalate co-precipitation, followed by the thermal co-conversion to a mixed oxide product. It is thus envisaged that future processes will avoid separation of plutonium from uranium and instead allow part of the uranium to flow with the plutonium, resulting in co-precipitation as the oxalate, and finally co-conversion to a mixed uranium-plutonium oxide (MOX), which can be fabricated into recycled nuclear fuel for further energy generation. The co-crystallisation of uranium (IV) and plutonium (III) into a single oxalate structure ensures the homogenous distribution of the 2 actinides at the molecular scale. The joint conversion of uranium and plutonium to the oxide form makes it possible to remove the complicated step of blending and grinding the 2 distinct oxide powders, as currently employed for the purposes of MOX fuel fabrication. This concept can also be extended to other actinides, including minor actinides from partitioning processes such as SANEX (Selective Actinide Extraction) and GANEX (Grouped Actinide Extraction) processes or even a thorium containing product from recycle of thorium based fuels. A selection of U_xTh_1_-_x(C_2O_4)_2 solids at varying concentrations of uranium and thorium were prepared by oxalate co-precipitation. Uranium (VI) was conditioned electrochemically at -0.7 V to uranium (IV), in the presence of hydrazine. The reduced uranium (IV) in nitric acid was mixed with thorium nitrate solutions at different concentration ratios with oxalic acid. The mixed tetravalent uranium-thorium oxalate solid products have been characterised by Raman and IR spectroscopies. The influence of thorium substituted into the uranium oxalate structure was evaluated. Several vibrational modes

Electrochemical Sensors for Clinic Analysis

Directory of Open Access Journals (Sweden)

Guang Li

2008-03-01

Full Text Available Demanded by modern medical diagnosis, advances in microfabrication technology have led to the development of fast, sensitive and selective electrochemical sensors for clinic analysis. This review addresses the principles behind electrochemical sensor design and fabrication, and introduces recent progress in the application of electrochemical sensors to analysis of clinical chemicals such as blood gases, electrolytes, metabolites, DNA and antibodies, including basic and applied research. Miniaturized commercial electrochemical biosensors will form the basis of inexpensive and easy to use devices for acquiring chemical information to bring sophisticated analytical capabilities to the non-specialist and general public alike in the future.

Electrochemical reduction study of Eu3+ in perchlorid media by cyclic chronopotentiometry

International Nuclear Information System (INIS)

Brotto, M.E.; Rabockai, T.

1990-01-01

The electrochemical reduction of Eu 3+ in perchloric media was studied by means of cyclic chronopotentiometry. It is shown that the charge transfer reaction is followed by a chemical reaction in which Eu 2+ ion reoxydized to the trivalent ion (catalytic reaction scheme). The mean value of the homogeneous reaction rate constant is (2,43 +- 0,24) x 10 -2 dm 3 .mol -1 . (author)

Electrochemical biosensors for hormone analyses.

Science.gov (United States)

Bahadır, Elif Burcu; Sezgintürk, Mustafa Kemal

2015-06-15

Electrochemical biosensors have a unique place in determination of hormones due to simplicity, sensitivity, portability and ease of operation. Unlike chromatographic techniques, electrochemical techniques used do not require pre-treatment. Electrochemical biosensors are based on amperometric, potentiometric, impedimetric, and conductometric principle. Amperometric technique is a commonly used one. Although electrochemical biosensors offer a great selectivity and sensitivity for early clinical analysis, the poor reproducible results, difficult regeneration steps remain primary challenges to the commercialization of these biosensors. This review summarizes electrochemical (amperometric, potentiometric, impedimetric and conductometric) biosensors for hormone detection for the first time in the literature. After a brief description of the hormones, the immobilization steps and analytical performance of these biosensors are summarized. Linear ranges, LODs, reproducibilities, regenerations of developed biosensors are compared. Future outlooks in this area are also discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterisation of semiconductor materials for ionising radiation detectors

International Nuclear Information System (INIS)

Vaitkus, J.; Gaubas, E.; Jasinskaite, R.; Juska, G.; Kazukauskas, V.; Puras, R.; Rahman, M.; Sakalauskas, S.; Smith, K.

2002-01-01

Methods for the detection and characterisation of semiconductor material parameters and inhomogeneities are analysed. The peculiarities of different 'classical' material and structure characterisation methods are discussed. The methods of lifetime and surface recombination mapping and electric field distribution in the samples are presented. Some results of investigations of GaAs, Si and SiC are used for the characterisation of different peculiarities or methods

Electrochemical study of chemical properties in ethanolamine and its mixtures with water

International Nuclear Information System (INIS)

Grall, M.

1964-12-01

This work is concerned with the study of acid-base reactions and of complex formation in ethanolamine and its mixtures with water. The ionic product of the solvent has been determined by an electro-chemical study of the H + /H 2 system. The reduction curves for ethanolamine-water mixtures, for different acidities, have made it possible to follow the variations in the size of the pH domain as a function of the composition of the solvent. The form of this variation has been explained on the basis of the dielectric constant and the solvation of the proton by the ethanolamine. In the second part, the electrochemical systems of mercury have been studied by anodic polarography. In order to establish a parallel between the acid-base reactions and complex formation reactions, we have studied the stability of Hg (CN) 2 in water-ethanolamine mixtures. It has been possible to deduce the law for the variation of pK c with solvent composition. The representative graph of this function passes through a minimum for a proportion of about 50 per cent of ethanolamine as in the case of acids. This variation has been explained by the predominating influence of ε for ethanolamine propositions of over 50 per cent and by that of the solvation of Hg 2+ for proportions of under 50 per cent. (author) [fr

Characterisation of a Sr-90 based electron monochromator

CERN Document Server

Arfaoui, S; CERN; Casella, C; ETH Zurich

2015-01-01

This note describes the characterisation of an energy filtered Sr-90 source to be used in laboratory studies that require Minimum Ionising Particles (MIP) with a kinetic energy of up to approx. 2 MeV. The energy calibration was performed with a LYSO scintillation crystal read out by a digital Silicon Photomultiplier (dSiPM). The LYSO/dSiPM set-up was pre-calibrated using a Na-22 source. After introducing the motivation behind the usage of such a device, this note presents the principle and design of the electron monochromator as well as its energy and momentum characterisation.

ELECTROCHEMICAL PROMOTED CATALYSIS: TOWARDS PRACTICAL UTILIZATION

Directory of Open Access Journals (Sweden)

DIMITRIOS TSIPLAKIDES

2008-07-01

Full Text Available Electrochemical promotion (EP of catalysis has already been recognized as “a valuable development in catalytic research” (J. Pritchard, 1990 and as “one of the most remarkable advances in electrochemistry since 1950” (J. O’M. Bockris, 1996. Laboratory studies have clearly elucidated the phenomenology of electrochemical promotion and have proven that EP is a general phenomenon at the interface of catalysis and electrochemistry. The major progress toward practical utilization of EP is surveyed in this paper. The focus is given on the electropromotion of industrial ammonia synthesis catalyst, the bipolar EP and the development of a novel monolithic electropromoted reactor (MEPR in conjunction with the electropromotion of thin sputtered metal films. Future perspectives of electrochemical promotion applications in the field of hydrogen technologies are discussed.

Impedimetric method for physiologically characterisation of fungi

DEFF Research Database (Denmark)

Nielsen, Per Væggemose; Petersen, Karina

1998-01-01

Fungi are playing an important role in the food and pharmaceutical industry today, both as starter cultures, fermentation organisms, and as contaminants. Characterisation of fungal growth is normally time consuming as it includes measurements and study on a wide range of media at different...... temperatures, pH, water activity and atmosphere composition. Nevertheless is it important information in ecophysiological studies, where the growth potential by fungi are related to composition and storage of food. It is therefore of great interest to device a rapid method for characterisation of fungi.......The objective was to determine the growth phases of various fungi using an impedimetric method and compare this with traditional methods using agar plates, in order to determine if this rapid method can replace the traditional method.The method is based on impedimetric assessment of growth on the Bactometer 128...

Characterising the 750 GeV diphoton excess

International Nuclear Information System (INIS)

Bernon, Jérémy; Goudelis, Andreas; Kraml, Sabine; Mawatari, Kentarou; Sengupta, Dipan

2016-01-01

We study kinematic distributions that may help characterise the recently observed excess in diphoton events at 750 GeV at the LHC Run 2. Several scenarios are considered, including spin-0 and spin-2 750 GeV resonances that decay directly into photon pairs as well as heavier parent resonances that undergo three-body or cascade decays. We find that combinations of the distributions of the diphoton system and the leading photon can distinguish the topology and mass spectra of the different scenarios, while patterns of QCD radiation can help differentiate the production mechanisms. Moreover, missing energy is a powerful discriminator for the heavy parent scenarios if they involve (effectively) invisible particles. While our study concentrates on the current excess at 750 GeV, the analysis is general and can also be useful for characterising other potential diphoton signals in the future.

A high-performance flexible fibre-shaped electrochemical capacitor based on electrochemically reduced graphene oxide.

Science.gov (United States)

Li, Yingru; Sheng, Kaixuan; Yuan, Wenjing; Shi, Gaoquan

2013-01-11

A fibre-shaped solid electrochemical capacitor based on electrochemically reduced graphene oxide has been fabricated, exhibiting high specific capacitance and rate capability, long cycling life and attractive flexibility.

Characterising the disintegration properties of tablets in opaque media using texture analysis.

Science.gov (United States)

Scheuerle, Rebekah L; Gerrard, Stephen E; Kendall, Richard A; Tuleu, Catherine; Slater, Nigel K H; Mahbubani, Krishnaa T

2015-01-01

Tablet disintegration characterisation is used in pharmaceutical research, development, and quality control. Standard methods used to characterise tablet disintegration are often dependent on visual observation in measurement of disintegration times. This presents a challenge for disintegration studies of tablets in opaque, physiologically relevant media that could be useful for tablet formulation optimisation. This study has explored an application of texture analysis disintegration testing, a non-visual, quantitative means of determining tablet disintegration end point, by analysing the disintegration behaviour of two tablet formulations in opaque media. In this study, the disintegration behaviour of one tablet formulation manufactured in-house, and Sybedia Flashtab placebo tablets in water, bovine, and human milk were characterised. A novel method is presented to characterise the disintegration process and to quantify the disintegration end points of the tablets in various media using load data generated by a texture analyser probe. The disintegration times in the different media were found to be statistically different (Pdisintegration times from each other in human versus bovine milk (adjusted P value 0.1685). Copyright © 2015 Elsevier B.V. All rights reserved.

Flow-induced corrosion of absorbable magnesium alloy: In-situ and real-time electrochemical study

International Nuclear Information System (INIS)

Wang, Juan; Jang, Yongseok; Wan, Guojiang; Giridharan, Venkataraman; Song, Guang-Ling; Xu, Zhigang; Koo, Youngmi; Qi, Pengkai; Sankar, Jagannathan; Huang, Nan; Yun, Yeoheung

2016-01-01

Highlights: • An in-situ and real-time electrochemical monitoring of flow-induced corrosion of Mg alloy is designed in a vascular bioreactor. • Effect of hydrodynamics on corrosion kinetics, types, rates and products is analyzed. • Flow accelerates mass and electron transfer, leading to an increase in uniform and localized corrosions. • Flow increases not only the thickness of uniform corrosion product layer, but the removal rate of localized corrosion products. • Electrochemical impedance spectroscopy and linear polarization-measured polarization resistances provide a consistent correlation to corrosion rate calculated by computed tomography. - Abstract: An in-situ and real-time electrochemical study in a vascular bioreactor was designed to analyze corrosion mechanism of magnesium alloy (MgZnCa) under mimetic hydrodynamic conditions. Effect of hydrodynamics on corrosion kinetics, types, rates and products was analyzed. Flow-induced shear stress (FISS) accelerated mass and electron transfer, leading to an increase in uniform and localized corrosions. FISS increased the thickness of uniform corrosion layer, but filiform corrosion decreased this layer resistance at high FISS conditions. FISS also increased the removal rate of localized corrosion products. Impedance-estimated and linear polarization-measured polarization resistances provided a consistent correlation to corrosion rate calculated by computed tomography.

Electrochemical Implications of Defects in Carbon Nanotubes

Science.gov (United States)

Hall, Jonathan Peter

The electrochemical behavior of carbon nanotubes (CNTs) containing both intrinsic and extrinsically introduced defects has been investigated through the study of bamboo and hollow multi-walled CNT morphologies. The controlled addition of argon, hydrogen, and chlorine ions in addition to atomic hydrogen and magnesium vapor was used for varying the charge and type of extrinsic defects. To quantify changes in the CNTs upon treatment, Raman spectroscopy and electrochemical techniques were employed. It was indicated from Raman spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and chronopotentiometric experiments that the electrochemical response of hollow type CNTs could be tailored more significantly compared to bamboo type CNTs, which have innately high reactive site densities and are less amenable to modification. Total defect density and edge-plane-like defect concentrations monitored through Raman spectroscopy were used to correlate changes in the electrochemical response of the CNT electrodes as a function of treatment. The implementation of CNT electrodes in a prototypical electrolytic capacitor device was then explored and characterized. Dependencies on source current and redox couple concentration were evaluated, as well as changes in the total capacitance as a function of treatment. Cyclability studies were also performed as a function of source current magnitude to evaluate the longevity of the faradaic currents which typically decrease over time in other similar capacitors. This thesis then concludes with an overall summary of the themes and findings of the research presented in this work.

Electrochemical Study of Modified Glassy Carbon Electrode with Carboxyphenyl Diazonium Salt in Aqueous Solutions

Directory of Open Access Journals (Sweden)

Mariem BOUROUROU

2014-05-01

Full Text Available The covalent grafting of carboxyphenyl functionalities to planar carbon substrates by reaction with 2-carboxybenezenediazonium salt has been studied in aqueous acid solution. The surface was characterized, before and after the functionnalization process, by cyclic voltammetry, electrochemical impedance spectroscopy and linear sweep voltammetry (LSV in order to control and to prove the formation of a coating on the carbon surface. The results indicate the presence of substituted phenyl groups on the investigated surface. Electrochemical impedance measurements show that the slowing down of the electron transfer kinetics was more evident by increasing the number of cycles resulting to higher DEp and RCT parameters. Besides, the effect of the pH on the electron transfer processes of the Fe(CN63-/4- at the modified electrode is studied. By changing the solution pH the terminal group’s charge state would vary, based on which the surface pKa value is estimated.

Single-Molecule Electrochemical Gating in Ionic Liquids

DEFF Research Database (Denmark)

Kay, Nicola J.; Higgins, Simon J.; Jeppesen, Jan O.

2012-01-01

The single-molecular conductance of a redox active molecular bridge has been studied in an electrochemical single-molecule transistor configuration in a room-temperature ionic liquid (RTIL). The redox active pyrrolo-tetrathiafulvalene (pTTF) moiety was attached to gold contacts at both ends through...... −(CH2)6S– groups, and gating of the redox state was achieved with the electrochemical potential. The water-free, room-temperature, ionic liquid environment enabled both the monocationic and the previously inaccessible dicationic redox states of the pTTF moiety to be studied in the in situ scanning...... and decreases again as the second redox process is passed. This is described as an “off–on–off–on–off” conductance switching behavior. This molecular conductance vs electrochemical potential relation could be modeled well as a sequential two-step charge transfer process with full or partial vibrational...

Characterisation of fracture network and groundwater preferential ...

African Journals Online (AJOL)

Characterisation of fractured rocks and evaluation of fracture connectivity are essential for the study of subsurface flow and transport in fractured rock aquifers. In this study, we use a new method to present fracture networks and analyse the connectivity of the fractures, based on the technique of randomly-generated ...

Electrochemical study of the AISI 409 ferritic stainless steel: passive film stability and pitting nucleation and growth

International Nuclear Information System (INIS)

Souza, Juliana Sarango de; Oliveira, Leandro Antônio de; Antunes, Renato Altobelli; Sayeg, Isaac Jamil

2017-01-01

The aim of the present work was to study the passive film stability and pitting corrosion behavior of the AISI 409 stainless steel. The electrochemical tests were carried out in 0.1 M NaCl solution at room temperature. The general electrochemical behavior was assessed using electrochemical impedance spectroscopy (EIS) measurements whereas the semiconducting properties of the passive film were evaluated by the Mott-Schottky approach. Pitting corrosion was investigated using potentiodynamic and potentiostatic polarization tests. Surface morphology was examined using confocal laser scanning microscopy and scanning electron microscopy (SEM). Energy dispersive X-ray spectroscopy (EDS) analyses were carried out to identify the composition of precipitates that could act as preferential sites for the onset of pitting corrosion. The results showed that the passive film presents n-type semiconductive behavior. Grain boundaries played an important role as pitting initiation sites for the AISI 409 stainless steel. (author)

Electrochemical study of the AISI 409 ferritic stainless steel: passive film stability and pitting nucleation and growth

Energy Technology Data Exchange (ETDEWEB)

Souza, Juliana Sarango de [Universidade Federal de São Paulo (UNIFESP), Diadema, SP (Brazil). Departamento de Ciências Exatas e da Terra; Oliveira, Leandro Antônio de; Antunes, Renato Altobelli, E-mail: renato.antunes@ufabc.edu.br [Universidade Federal do ABC (CECS/UFABC), Santo André, SP (Brazil). Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas; Sayeg, Isaac Jamil [Universidade de São Paulo (USP), SP (Brazil). Instituto de Geociências

2017-11-15

The aim of the present work was to study the passive film stability and pitting corrosion behavior of the AISI 409 stainless steel. The electrochemical tests were carried out in 0.1 M NaCl solution at room temperature. The general electrochemical behavior was assessed using electrochemical impedance spectroscopy (EIS) measurements whereas the semiconducting properties of the passive film were evaluated by the Mott-Schottky approach. Pitting corrosion was investigated using potentiodynamic and potentiostatic polarization tests. Surface morphology was examined using confocal laser scanning microscopy and scanning electron microscopy (SEM). Energy dispersive X-ray spectroscopy (EDS) analyses were carried out to identify the composition of precipitates that could act as preferential sites for the onset of pitting corrosion. The results showed that the passive film presents n-type semiconductive behavior. Grain boundaries played an important role as pitting initiation sites for the AISI 409 stainless steel. (author)

Synthesis and characterisation of doxorubicin-loaded functionalised ...

African Journals Online (AJOL)

The synthesised cobalt ferrite nanoparticles (CFNPs) were functionalised with xanthine gum (XG) and subsequently characterised by Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and contact angle studies. Vibrating sample magnetometry (VSM) was used for magnetic measurements of ...

Optimization studies of HgSe thin film deposition by electrochemical atomic layer epitaxy (EC-ALE)

CSIR Research Space (South Africa)

Venkatasamy, V

2006-06-01

Full Text Available Studies of the optimization of HgSe thin film deposition using electrochemical atomic layer epitaxy (EC-ALE) are reported. Cyclic voltammetry was used to obtain approximate deposition potentials for each element. These potentials were then coupled...

Phenotypic characterisation and molecular polymorphism of ...

African Journals Online (AJOL)

The study of the phenotypic characterisation and molecular polymorphism of local chicken populations was carried out in Benin on 326 chickens of the Forest ecological area and 316 of the Savannah ecological area, all were 7 months old at least. The collection of blood for the molecular typing was achieved on 121 ...

Electrochemical oxidation of organic waste

International Nuclear Information System (INIS)

Almon, A.C.; Buchanan, B.R.

1990-01-01

Both silver catalyzed and direct electrochemical oxidation of organic species are examined in analytical detail. This paper describes the mechanisms, reaction rates, products, intermediates, capabilities, limitations, and optimal reaction conditions of the electrochemical destruction of organic waste. A small bench-top electrocell being tested for the treatment of small quantities of laboratory waste is described. The 200-mL electrochemical cell used has a processing capacity of 50 mL per day, and can treat both radioactive and nonradioactive waste. In the silver catalyzed process, Ag(I) is electrochemically oxidized to Ag(II), which attacks organic species such as tributylphosphate (TBP), tetraphenylborate (TPB), and benzene. In direct electrochemical oxidation, the organic species are destroyed at the surface of the working electrode without the use of silver as an electron transfer agent. This paper focuses on the destruction of tributylphosphate (TBP), although several organic species have been destroyed using this process. The organic species are converted to carbon dioxide, water, and inorganic acids

Characterising the disintegration properties of tablets in opaque media using texture analysis

OpenAIRE

Scheuerle, Rebekah L.; Gerrard, Stephen E.; Kendall, Richard A.; Tuleu, Catherine; Slater, Nigel K.H.; Mahbubani, Krishnaa T.

2015-01-01

Tablet disintegration characterisation is used in pharmaceutical research, development, and quality control. Standard methods used to characterise tablet disintegration are often dependent on visual observation in measurement of disintegration times. This presents a challenge for disintegration studies of tablets in opaque, physiologically relevant media that could be useful for tablet formulation optimisation. In this study is explored an application of texture analysis disintegration testin...

Electrochemical properties and electrochemical impedance spectroscopy of polypyrrole-coated platinum electrodes

Directory of Open Access Journals (Sweden)

M. Fall

2006-12-01

Full Text Available Polypyrrole (PPy films of different thickness were characterized by electrochemical impedance spectroscopy (EIS measurements in acetonitrile and aqueous solutions, containing 0.1 M NaClO4 or sodium dodecylsulfate as the dopant. The PPy films were electrochemically deposited on Pt, and their electrochemical properties studied by cyclic voltammetry. Impedance spectra were obtained at potentials ranging from 0 to 0.8 V/SCE. The EIS data were fitted using two different equivalent electrical circuits (depending on the nature of the dopant. They involve a diffusive capacitance, which increased with the passing charge during electrosynthesis (i.e. film thickness for ClO4--doped PPy, but was practically unaffected by the film thickness in the case of SDS-doped PPy. Also, a double-layer capacitance was found only in the circuit of ClO4--doped PPy. It increased with the film thickness, and showed a minimum near the open-circuit potential. Finally the charge-transfer resistance (Rct obtained with SDS is nearly 200-fold higher than that obtained with ClO4- in the same solvent (H2O. With the same dopant (ClO4-, Rct is about five times higher in acetonitrile relative to water. All these EIS results of the different types of PPy suggest a relation with the wettability of the polymer.

Characterisation of wastewater for modelling of wastewater ...

African Journals Online (AJOL)

Bio-process modelling is increasingly used in design, modification and troubleshooting of wastewater treatment plants (WWTPs). Characterisation of the influent wastewater to a WWTP is an important part of developing such a model. The characterisation required for modelling is more detailed than that routinely employed ...

Characterisation and application of NovaFiber lignin

NARCIS (Netherlands)

Gosselink, R.J.A.; Snijder, M.H.B.; Kranenbarg, A.; Keijsers, E.R.P.; Jong, de E.; Stigsson, L.L.

2004-01-01

Sulphur-free lignin coming from a novel alkaline-pulping process called NovaFiber, which has been developed by KIRAM AB, has been characterised and evaluated for potential applications. A Kraft lignin has been used for comparison. Considering the characterisation results of a NovaFiber softwood and

Characterisation of nanomaterial hydrophobicity using engineered surfaces

Energy Technology Data Exchange (ETDEWEB)

Desmet, Cloé; Valsesia, Andrea; Oddo, Arianna; Ceccone, Giacomo; Spampinato, Valentina; Rossi, François; Colpo, Pascal, E-mail: pascal.colpo@ec.europa.eu [Directorate Health, Consumer and Reference Materials, Consumer Products Safety Unit (Italy)

2017-03-15

Characterisation of engineered nanomaterials (NMs) is of outmost importance for the assessment of the potential risks arising from their extensive use. NMs display indeed a large variety of physico-chemical properties that drastically affect their interaction with biological systems. Among them, hydrophobicity is an important property that is nevertheless only slightly covered by the current physico-chemical characterisation techniques. In this work, we developed a method for the direct characterisation of NM hydrophobicity. The determination of the nanomaterial hydrophobic character is carried out by the direct measurement of the affinity of the NMs for different collectors. Each collector is an engineered surface designed in order to present specific surface charge and hydrophobicity degrees. Being thus characterised by a combination of surface energy components, the collectors enable the NM immobilisation with surface coverage in relation to their hydrophobicity. The experimental results are explained by using the extended DLVO theory, which takes into account the hydrophobic forces acting between NMs and collectors.

Morphological reason for enhancement of electrochemical double layer capacitances of various acetylene blacks by electrochemical polarization

International Nuclear Information System (INIS)

Kim, Taegon; Ham, Chulho; Rhee, Choong Kyun; Yoon, Seong-Ho; Tsuji, Masaharu; Mochida, Isao

2008-01-01

Enhancement of electrochemical capacitance and morphological variations of various acetylene blacks caused by electrochemical polarization are presented. Acetylene blacks of different mean particle diameters were modified by air-oxidation and heat treatment to diversify the morphologies of the acetylene blacks before electrochemical polarization. The various acetylene blacks were electrochemically oxidized at 1.6 V (vs. Ag/AgCl) for 10 s and the polarization step was repeated until the capacitance values did not change any longer. These polarization steps enhanced the capacitances of the acetylene blacks and the specific enhancement factors range from 2 to 5.5. Such an enhancement is strongly related to morphological modification as revealed by transmission electron microscopic observations. The electrochemical polarization resulted in formation of tiny graphene sheets on the wide graphitic carbon surfaces, which were most responsible for the observed capacitive enhancement. Although the pseudo-capacitance increased after polarization by forming oxygenated species on the surfaces, its contribution to the total capacitance was less than 10%. The mechanism of the formation of the tiny graphene sheets during the electrochemical oxidation is described schematically

Characterisation of COPD heterogeneity in the ECLIPSE cohort

DEFF Research Database (Denmark)

Agusti, Alvar; Calverley, Peter M A; Celli, Bartolome

2010-01-01

Chronic obstructive pulmonary disease (COPD) is a complex condition with pulmonary and extra-pulmonary manifestations. This study describes the heterogeneity of COPD in a large and well characterised and controlled COPD cohort (ECLIPSE)....

TEM characterisation of stress corrosion cracks in nickel based alloys: effect of chromium content and chemistry of environment

International Nuclear Information System (INIS)

Delabrouille, F.

2004-11-01

Stress corrosion cracking (SCC) is a damaging mode of alloys used in pressurized water reactors, particularly of nickel based alloys constituting the vapour generator tubes. Cracks appear on both primary and secondary sides of the tubes, and more frequently in locations where the environment is not well defined. SCC sensitivity of nickel based alloys depends of their chromium content, which lead to the replacement of alloy 600 (15 % Cr) by alloy 690 (30 % Cr) but this phenomenon is not yet very well understood. The goal of this thesis is two fold: i) observe the effect of chromium content on corrosion and ii) characterize the effect of environment on the damaging process of GV tubes. For this purpose, one industrial tube and several synthetic alloys - with controlled chromium content - have been studied. Various characterisation techniques were used to study the corrosion products on the surface and within the SCC cracks: SIMS; TEM - FEG: thin foil preparation, HAADF, EELS, EDX. The effect of chromium content and surface preparation on the generalised corrosion was evidenced for synthetic alloys. Moreover, we observed the penetration of oxygen along triple junctions of grain boundaries few micrometers under the free surface. SCC tests show the positive effect of chromium for contents varying from 5 to 30 % wt. Plastic deformation induces a modification of the structure, and thus of the protective character, of the internal chromium rich oxide layer. SCC cracks which developed in different chemical environments were characterised by TEM. The oxides which are formed within the cracks are different from what is observed on the free surface, which reveals a modification of medium and electrochemical conditions in the crack. Finally we were able to evidence some structural characteristics of the corrosion products (in the cracks and on the surface) which turn to be a signature of the chemical environment. (author)

Electrical and Electrochemical Properties of Conducting Polymers

Directory of Open Access Journals (Sweden)

Thanh-Hai Le

2017-04-01

Full Text Available Conducting polymers (CPs have received much attention in both fundamental and practical studies because they have electrical and electrochemical properties similar to those of both traditional semiconductors and metals. CPs possess excellent characteristics such as mild synthesis and processing conditions, chemical and structural diversity, tunable conductivity, and structural flexibility. Advances in nanotechnology have allowed the fabrication of versatile CP nanomaterials with improved performance for various applications including electronics, optoelectronics, sensors, and energy devices. The aim of this review is to explore the conductivity mechanisms and electrical and electrochemical properties of CPs and to discuss the factors that significantly affect these properties. The size and morphology of the materials are also discussed as key parameters that affect their major properties. Finally, the latest trends in research on electrochemical capacitors and sensors are introduced through an in-depth discussion of the most remarkable studies reported since 2003.

FABRICATION AND CHARACTERIZATION OF POLYANILINE-GRAPHENE COMPOSITE AS ELECTRODE IN ELECTROCHEMICAL CAPACITOR

Directory of Open Access Journals (Sweden)

H. Adelkhani

2016-06-01

Full Text Available In this study, polyaniline-graphene composites with different nano-structures are synthesized and the behaviour of the obtained composites serving as electrode materials in electrochemical capacitors is studied. The morphology, crystal structure, and thermal stability of the composites are examined using scanning electron microscopy (SEM, X-ray diffraction (XRD, and Thermal gravimetric analysis (TGA. Electrochemical properties are characterized by cyclic voltammetry (CV. According to the results, the obtained composites show different crystal structures and different thermal stabilities, and consequently different electrochemical capacities, when used as electrodes in electrochemical capacitors. A nano-fibre composite is shown to have a good degree of crystallization, 5.17% water content, 637oC degradation onset temperature, and 379 Fg-1 electrochemical capacity.

ONKALO. Underground characterisation and research programme (UCRP)

International Nuclear Information System (INIS)

2003-09-01

The purpose of the ONKALO Underground Characterisation and Research Programme (UCRP) is to explore Olkiluoto rock conditions and thereby enhance the current geoscientific understanding of the site, to allow the submission of an application for a construction licence for the deep repository. The characterisation programme has the following geoscientific goals: to develop and demonstrate techniques for detailed characterising volumes of rock from the underground, to update the current descriptive model of Olkiluoto bedrock and to increase confidence in this model such that it will serve the needs of construction and the Preliminary Safety Assessment Report (PSAR) in the construction licence application, and to identify volumes of rock that could be suitable for housing parts of the repository. The development of ONKALO will be based on coordinated investigation, design and construction activities. Mapping data from the tunnel front and data obtained from short probe holes will constitute most of the data needed to control the construction of ONKALO. Pilot holes will be drilled along the tunnel profile as the excavation proceeds and investigations will be carried out for geological, rock mechanics, hydrogeological and hydrogeochemical characterisation. Investigations cover more detailed mapping and sampling in parts of the tunnel, mapping and sampling of potential groundwater inflows to the tunnel and investigations from characterisation bore holes drilled from ONKALO. In addition, monitoring is planned in surface-drilled boreholes, in boreholes drilled from ONKALO, and in ONKALO itself. Monitoring will reveal changes in bedrock conditions and thus provide important information for site characterisation. The information collected by characterisation and monitoring will all be assessed in an integrated modelling effort. The aim of this modelling is both to successively enhance the description and understanding of the rock volume around ONKALO and to assess potential

A microfluidic chip for electrochemical conversions in drug metabolism studies

NARCIS (Netherlands)

Odijk, Mathieu; Baumann, A.; Lohmann, W.; van den Brink, Floris Teunis Gerardus; Olthuis, Wouter; Karst, U.; van den Berg, Albert

2009-01-01

We have designed a microfluidic microreactor chip for electrochemical conversion of analytes, containing a palladium reference electrode and platinum working and counter electrodes. The counter electrode is placed in a separate side-channel on chip to prevent unwanted side-products appearing in the

CO2 Storage Feasibility: A Workflow for Site Characterisation

Directory of Open Access Journals (Sweden)

Nepveu Manuel

2015-04-01

Full Text Available In this paper, we present an overview of the SiteChar workflow model for site characterisation and assessment for CO2 storage. Site characterisation and assessment is required when permits are requested from the legal authorities in the process of starting a CO2 storage process at a given site. The goal is to assess whether a proposed CO2 storage site can indeed be used for permanent storage while meeting the safety requirements demanded by the European Commission (EC Storage Directive (9, Storage Directive 2009/31/EC. Many issues have to be scrutinised, and the workflow presented here is put forward to help efficiently organise this complex task. Three issues are highlighted: communication within the working team and with the authorities; interdependencies in the workflow and feedback loops; and the risk-based character of the workflow. A general overview (helicopter view of the workflow is given; the issues involved in communication and the risk assessment process are described in more detail. The workflow as described has been tested within the SiteChar project on five potential storage sites throughout Europe. This resulted in a list of key aspects of site characterisation which can help prepare and focus new site characterisation studies.

Electrochemical gating in scanning electrochemical microscopy

NARCIS (Netherlands)

Ahonen, P.; Ruiz, V.; Kontturi, K.; Liljeroth, P.; Quinn, B.M.

2008-01-01

We demonstrate that scanning electrochemical microscopy (SECM) can be used to determine the conductivity of nanoparticle assemblies as a function of assembly potential. In contrast to conventional electron transport measurements, this method is unique in that electrical connection to the film is not

Feasibility studies on electrochemical separation and recovery of uranium by using domestic low grade uranium resources

International Nuclear Information System (INIS)

Oh, Won Zin; Jung, Chong Hun; Lee, Kune Woo; Won, Hui Jun; Choi, Wang Kyu; Kim, Gye Nam; Lee, Yu Ri; Lee, Joong Moung

2005-12-01

The up-to-date electrochemical uranium separation technology has been developed for uranium sludge waste treatment funded by a long term national nuclear technology development program. The objective of the studies is to examine applicability of the uranium separation technology to making use of the low grade uranium resources in the country. State of the arts of uranium separation and recovery from the low grade national uranium resources. - The amount of the high grade uranium resources(0.1 % U 3 O 8 contents) in the world is 1,750,000MTU and that of the low grade uranium resources(0.04 % U 3 O 8 contents) in the country is 340,000MTU. - The world uranium price will be increase to more than 30$/l0b in 10 years, so that the low grade uranium in the country become worth while to recover. - The conventional uranium recovery technologies are based on both acidic - The ACF electrochemical uranium separation technology is the state of the art technology in the world and the adsorption capability of 690 mgU/g is several ten times higher than that of a conventional zeolite and the uranium stripping efficiency by desorption is more than 99%. So, this technology is expected to replace the existing solvent extraction technology. Feasibility of the ACF electrochemical uranium separation technology as an uranium recovery method. Lab scale demonstration of uranium separation and recovery technologies have been carried out by using an ACF electrochemical method

Electrochemical redox reactions in solvated silica sol-gel glass

International Nuclear Information System (INIS)

Opallo, M.

2002-01-01

The studies of electrochemical redox reactions in solvated silica sol-gel glass were reviewed. The methodology of the experiments with emphasis on the direct preparation of the solid electrolyte and the application ultra microelectrodes was described. Generally, the level of the electrochemical signal is not much below that observed in liquid electrolyte. The current depends on time elapsed after gelation, namely the longer time, the smaller current. The differences between electrochemical behaviour of the redox couples in monoliths and thin layers were described. (author)

Characterisation of bovine epiblast-derived outgrowth colonies

DEFF Research Database (Denmark)

Østrup, Esben; Gjørret, Jakob; Schauser, Kirsten Hallundbæk

2010-01-01

The aim of the present study was to characterise bovine epiblast-derived outgrowth colonies (OCs) with respect to the embryonic origin of their cellular components. Epiblasts were isolated mechanically from bovine Day 12 embryos. Epiblasts were cultured on feeder layers of SNL cells (neomycin...

Aerobic and Electrochemical Oxidations with N-Oxyl Reagents

Science.gov (United States)

Miles, Kelsey C.

Selective oxidation of organic compounds represents a significant challenge for chemical transformations. Oxidation methods that utilize nitroxyl catalysts have become increasingly attractive and include Cu/nitroxyl and nitroxyl/NO x co-catalyst systems. Electrochemical activation of nitroxyls is also well known and offers an appealing alternative to the use of chemical co-oxidants. However, academic and industrial organic synthetic communities have not widely adopted electrochemical methods. Nitroxyl catalysts facilitate effective and selective oxidation of alcohols and aldehydes to ketones and carboxylic acids. Selective benzylic, allylic, and alpha-heteroatom C-H abstraction can also be achieved with nitroxyls and provides access to oxygenated products when used in combination with molecular oxygen as a radical trap. This thesis reports various chemical and electrochemical oxidation methods that were developed using nitroxyl mediators. Chapter 1 provides a short review on practical aerobic alcohol oxidation with Cu/nitroxyl and nitroxyl/NO x systems and emphasizes the utility of bicyclic nitroxyls as co-catalysts. In Chapter 2, the combination of these bicyclic nitroxyls with NOx is explored for development of a mild oxidation of alpha-chiral aryl aldehydes and showcases a sequential asymmetric hydroformylation/oxidation method. Chapter 3 reports the synthesis and characterization of two novel Cu/bicyclic nitroxyl complexes and the electronic structure analysis of these complexes. Chapter 4 highlights the electrochemical activation of various nitroxyls and reports an in-depth study on electrochemical alcohol oxidation and compares the reactivity of nitroxyls under electrochemical or chemical activation. N-oxyls can also participate in selective C-H abstraction, and Chapter 5 reports the chemical and electrochemical activation of N-oxyls for radical-mediated C-H oxygenation of (hetero)arylmethanes. For these electrochemical transformations, the development of

Waste package characterisation

Energy Technology Data Exchange (ETDEWEB)

Sannen, L.; Bruggeman, M.; Wannijn, J.P

1998-09-01

Radioactive wastes originating from the hot labs of the Belgian Nuclear Research Centre SCK-CEN contain a wide variety of radiotoxic substances. The accurate characterisation of the short- and long-term radiotoxic components is extremely difficult but required in view of geological disposal. This paper describes the methodology which was developed and adopted to characterise the high- and medium-level waste packages at the SCK-CEN hot laboratories. The proposed method is based on the estimation of the fuel inventory evacuated in a particular waste package; a calculation of the relative fission product contribution on the fuel fabrication and irradiation footing; a comparison of the calculated, as expected, dose rate and the real measured dose rate of the waste package. To cope with the daily practice an appropriate fuel inventory estimation route, a user friendly computer programme for fission product and corresponding dose rate calculation, and a simple dose rate measurement method have been developed and implemented.

Waste package characterisation

International Nuclear Information System (INIS)

Sannen, L.; Bruggeman, M.; Wannijn, J.P.

1998-09-01

Radioactive wastes originating from the hot labs of the Belgian Nuclear Research Centre SCK-CEN contain a wide variety of radiotoxic substances. The accurate characterisation of the short- and long-term radiotoxic components is extremely difficult but required in view of geological disposal. This paper describes the methodology which was developed and adopted to characterise the high- and medium-level waste packages at the SCK-CEN hot laboratories. The proposed method is based on the estimation of the fuel inventory evacuated in a particular waste package; a calculation of the relative fission product contribution on the fuel fabrication and irradiation footing; a comparison of the calculated, as expected, dose rate and the real measured dose rate of the waste package. To cope with the daily practice an appropriate fuel inventory estimation route, a user friendly computer programme for fission product and corresponding dose rate calculation, and a simple dose rate measurement method have been developed and implemented

Electrochemical sensor for detection of carcinoma

International Nuclear Information System (INIS)

Thakur, Bhawana; Sawant, Shilpa N.; Jayakumar, S.

2012-01-01

Detection of carcinoma in early stage is very important for its effective treatment. Although considerable advancement has been made in its detection and treatment, there is a significant need for rapid, low-cost, sensitive, and selective biosensors for detection of cancer. In recent years, electrochemical detection techniques have received much attention due to their rapid response, high sensitivity, and inherent selectivity. They can provide an inexpensive platform for detection of analytes in clinical diagnostics. Conducting polymers are a versatile material for development of electrochemical biosensors. Due to the conducting nature of these polymers, they act as a transducer to convert the biological signal into electrical signal. These polymers also exhibit good biocompatibility, hence are ideal for immobilisation of biological recognition element during the development of the sensor film. Recently author have demonstrated a whole cell based electrochemical biosensor for detection of the pesticide Lindane at very low concentrations. In the present study, we have tried to develop polyaniline based electrochemical sensor for detection of carcinoma. Polyaniline was deposited on gold interdigitated electrodes by electropolymerization using potentiodynamic method. The polymer film was suitably modified to obtain the sensor film for recognition of the tumour cells. Response of the sensor to various tumour cells such as lung cancer cells, human fibrosarcoma cells, prostate cancer cells, breast cancer cells was studied and was compared to that of normal cells. The sensor electrode could detect tumour cells based on the nature of response obtained

Water-mediated electrochemical nano-writing on thin ceria films

International Nuclear Information System (INIS)

Yang, Nan; Doria, Sandra; Tebano, Antonello; Licoccia, Silvia; Balestrino, Giuseppe; Kumar, Amit; Arruda, Thomas M; Jesse, Stephen; Ivanov, Ilia N; Baddorf, Arthur P; Strelcov, Evgheni; Kalinin, Sergei V; Jang, Jae Hyuck; Borisevich, Albina Y

2014-01-01

Bias dependent mechanisms of irreversible cathodic and anodic processes on a pure CeO 2 film are studied using modified atomic force microscopy (AFM). For a moderate positive bias applied to the AFM tip an irreversible electrochemical reduction reaction is found, associated with significant local volume expansion. By changing the experimental conditions we are able to deduce the possible role of water in this process. Simultaneous detection of tip height and current allows the onset of conductivity and the electrochemical charge transfer process to be separated, further elucidating the reaction mechanism. The standard anodic/cathodic behavior is recovered in the high bias regime, where a sizable transport current flows between the tip and the film. These studies give insight into the mechanisms of the tip-induced electrochemical reactions as mediated by electronic currents, and into the role of water in these processes, as well as providing a different approach for electrochemical nano-writing. (paper)

The Scandinavian baltic pancreatic club (SBPC) database: design, rationale and characterisation of the study cohort.

Science.gov (United States)

Olesen, Søren S; Poulsen, Jakob L; Drewes, Asbjørn M; Frøkjær, Jens B; Laukkarinen, Johanna; Parhiala, Mikael; Rix, Iben; Novovic, Srdan; Lindkvist, Björn; Bexander, Louise; Dimcevski, Georg; Engjom, Trond; Erchinger, Friedemann; Haldorsen, Ingfrid S; Pukitis, Aldis; Ozola-Zālīte, Imanta; Haas, Stephan; Vujasinovic, Miroslav; Löhr, J Matthias; Gulbinas, Antanas; Jensen, Nanna M; Jørgensen, Maiken T; Nøjgaard, Camilla

2017-08-01

Chronic pancreatitis (CP) is a multifaceted disease associated with several risk factors and a complex clinical presentation. We established the Scandinavian Baltic Pancreatic Club (SBPC) Database to characterise and study the natural history of CP in a Northern European cohort. Here, we describe the design of the database and characteristics of the study cohort. Nine centres from six different countries in the Scandinavian-Baltic region joined the database. Patients with definitive or probable CP (M-ANNHEIM diagnostic criteria) were included. Standardised case report forms were used to collect several assessment variables including disease aetiology, duration of CP, preceding acute pancreatitis, as well as symptoms, complications, and treatments. The clinical stage of CP was characterised according to M-ANNNHEIM. Yearly follow-up is planned for all patients. The study cohort comprised of 910 patients (608 men: 302 women; median age 58 (IQR: 48-67) years with definite 848 (93%) or probable CP 62 (7%). Nicotine (70%) and alcohol (59%) were the most frequent aetiologies and seen in combination in 44% of patients. A history of recurrent acute pancreatitis was seen in 49% prior to the development of CP. Pain (69%) and exocrine pancreatic insufficiency (68%) were the most common complications followed by diabetes (43%). Most patients (30%) were classified as clinical stage II (symptomatic CP with exocrine or endocrine insufficiency). Less than 10% of the patients had undergone pancreatic surgery. The SBPC database provides a mean for future prospective, observational studies of CP in the Northern European continent.

The characterisation of precipitated magnetites

International Nuclear Information System (INIS)

Rush, D.F.; Segal, D.L.

1982-06-01

Methods are described for the preparation of magnetite by precipitation from aqueous solutions of iron(II) and iron(III) salts. The magnetites have been characterised by transmission electron microscopy, chemical analysis and X-ray diffraction. Transmission Moessbauer spectroscopy has also been used to characterise precipitated magnetites and a comparison of the spectra has been made with those obtained from nickel ferrite and hydrated ferric oxides. The hydrothermal stability of magnetite at 573 K has also been investigated. This work is relevant to corrosion processes that can occur in the water coolant circuits of nuclear reactors. (author)

Electrochemical degradation of the chloramphenicol at flow reactor

International Nuclear Information System (INIS)

Rezende, Luis Gustavo P.; Prado, Vania M. do; Rocha, Robson S.; Beati, Andre A.G.F.; Sotomayor, Maria del Pilar T.; Lanza, Marcos R.V.

2010-01-01

This paper reports a study of electrochemical degradation of the chloramphenicol antibiotic in aqueous medium using a flow-by reactor with DSA anode. The process efficiency was monitored by chloramphenicol concentration analysis with liquid chromatography (HPLC) during the experiments. Analysis of Total Organic Carbon (TOC) was performed to estimate the degradation degree and Ion Chromatography (IC) was performed to determinate inorganic ions formed during the electrochemical degradation process. In electrochemical flow-by reactor, 52% of chloramphenicol was degraded, with 12% TOC reduction. IC analysis showed the production of chloride ions (25 mg L -1 ), nitrate ions (6 mg L -1 ) and nitrite ions (4.5 mg L -1 ). (author)

Pulse electrochemical meso/micro/nano ultraprecision machining technology.

Science.gov (United States)

Lee, Jeong Min; Kim, Young Bin; Park, Jeong Woo

2013-11-01

This study demonstrated meso/micro/nano-ultraprecision machining through electrochemical reactions using intermittent DC pulses. The experiment focused on two machining methods: (1) pulse electrochemical polishing (PECP) of stainless steel, and (2) pulse electrochemical nano-patterning (PECNP) on a silicon (Si) surface, using atomic force microscopy (AFM) for fabrication. The dissolution reaction at the stainless steel surface following PECP produced a very clean, smooth workpiece. The advantages of the PECP process included improvements in corrosion resistance, deburring of the sample surface, and removal of hydrogen from the stainless steel surface as verified by time-of-flight secondary-ion mass spectrometry (TOF-SIMS). In PECNP, the electrochemical reaction generated within water molecules produced nanoscale oxide textures on a Si surface. Scanning probe microscopy (SPM) was used to evaluate nanoscale-pattern processing on a Si wafer surface produced by AFM-PECNP For both processes using pulse electrochemical reactions, three-dimensional (3-D) measurements and AFM were used to investigate the changes on the machined surfaces. Preliminary results indicated the potential for advancing surface polishing techniques and localized micro/nano-texturing technology using PECP and PECNP processes.

Spectroscopic and electrochemical study of polynuclear clusters from ruthenium acetate

International Nuclear Information System (INIS)

Cipriano, C.

1989-01-01

The chemistry of the trinuclear clusters [Ru sub(3) O (CH sub(3) CO sub(2)) sub(4) L sub(3)] where L = imidazole, pyridine or pyrazine type of ligands, was investigated based on spectroscopic and electrochemical techniques. These complexes are of great interest from the point of view of their electronic and redox properties, providing multisite species for electron transfer processes. They were isolated in solid state, and characterized by means of elementary analyses and infrared spectra. The electrochemical behaviour in acetonitrile solution was typically reversible; the cyclic voltammograms exhibited a series of four or five mono electronic waves ascribed to the sucessive Ru sup(IV) Ru sup(III) Ru sup(III) / Ru sup(III) Ru sup(III) Ru sup(III)/ --- Ru sup(II) Ru sup(II) Ru sup(II) redox couples. The differences between the successive redox potentials were about 1 V, indicating strong metal-metal interaction in the trinuclear Ru sub(3) centre. The E values were strongly sensitive to the nature of the N-heterocyclic ligand, increasing with the pi-acceptor properties of the pyridine and pyrazine derivatives, but in a much less pronounced way in the case of the imidazole derivatives. Resonance Raman studies for the pyrazine cluster showed selective intensification of the vibrational modes of the Ru-pyrazine chromophore, and the trinuclear centre, using excitation wavelengths coinciding with the metal-to-pyrazine and metal-metal bands, respectively. (author)

Study on the Efficient Disintegration of HTGR Fuel Elements by Electrochemical Method

International Nuclear Information System (INIS)

Piao Nan; Chen Ji; Xiao Cuiping; We Mingfen; Che Jing

2014-01-01

The spent fuel elements in High- temperature gas-cooled reactor (HTGR) have a special structure, so the head-end process of the spent fuel reprocessing is different from the process of water reactor spent fuel. The first step of head-end process of the HTGR spent fuel reprocessing process is disintegration of the graphite matrix and separation of the coated fuel particles. Electrochemical method with nitrate solution as an electrolyte for fuel element disintegration has been conducted by the Institute of Nuclear and New Energy Technology in Tsinghua University. This method allows a total disintegration of graphite matrix, while still preserving the integrity of TRISO particles. The influences of the pretreatment methods such as heating oxidation of graphite, hydrothermal and oxidants oxidation were investigated in the present work. The experimental results showed that there were no significant effects on increasing the disintegration rate when pretreatment methods were used ahead of electrochemical disintegration. This phenomenon indicated that the fuel elements which were calcined at 1073 K and pressed under 300 MPa are too compact to be broken by these pretreatment methods. And the electrochemical disintegration is an effective but slow method in breaking the graphite matrix. (author)

Characterisation of gold from Fiji

OpenAIRE

Naden, Jon; Henney, P.J.

1995-01-01

This is a study of the variation in chemistry and inclusion mineralogy of bedrock and placer gold from Fiji. It forms part of a large project, undertaking gold characterisation from a wide range of geological environments in Ecuador, Zimbabwe, Malaysia and Fiji. The work was carried out under the Overseas Development AdministratiodBritish Geological Survey Technology Development and Research programme (Project R5549) as part of the British Government’s provision of technical...

Molecularly imprinted polymer based electrochemical detection of L-cysteine at carbon paste electrode.

Science.gov (United States)

Aswini, K K; Vinu Mohan, A M; Biju, V M

2014-04-01

A methacrylic acid (MAA) based molecularly imprinted polymer (MIP) modified carbon paste electrode (CPE) was developed for electrochemical detection of L-cysteine (Cys). Characterisation of MIP was done with FTIR and the modified electrode with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). CV, DPV and impedance analysis demonstrated that the modified electrode is responsive towards the target molecule. The optimum percentage composition of MIP for MIP/CPE and the effect of pH towards the electrode response for Cys were studied. The detection of Cys in the range of 2×10(-8) to 18×10(-8)M at MIP/CPE was monitored by DPV with a limit of detection of 9.6nM and R(2) of 0.9974. Also, various physiological interferents such as ascorbic acid, L-tryptophan, D-glucose, D-cysteine and L-cysteine were found to have little effect on DPV response at MIP/CPE. The utility of the electrode was proved by the effective detection of Cys from tap water and human blood plasma samples with reproducible results. Copyright © 2014 Elsevier B.V. All rights reserved.

Electrochemical impedance characterization of FeSn2 electrodes for Li-ion batteries

International Nuclear Information System (INIS)

Chamas, M.; Lippens, P-E.; Jumas, J-C.; Hassoun, J.; Panero, S.; Scrosati, B.

2011-01-01

Highlights: → In this paper we study a tin based, FeSn 2 , high capacity lithium-alloying electrode. → The electrochemical performance of this electrode in lithium batteries is remarkably influenced by the current rate. → This aspect is investigated by electrochemical techniques such as galvanostatic cycling and impedance spectroscopy. → The results demonstrated that the good electrochemical behavior of the electrode at the higher currents is due to the formation of a stable solid electrolyte interphase (SEI) film. - Abstract: This work reports the electrochemical characterization of a micro-scale FeSn 2 electrode in a lithium battery. The electrode is proposed as anode material for advanced lithium ion batteries due to its characteristics of high capacity (500 mAh g -1 ) and low working voltage (0.6 V vs. Li). The electrochemical alloying process is studied by cyclic voltammetry and galvanostatic cycling while the interfacial properties are investigated by electrochemical impedance spectroscopy. The impedance measurements in combination with the galvanostatic cycling tests reveal relatively low overall impedance values and good electrochemical performance for the electrode, both in terms of delivered capacity and cycling stability, even at the higher C-rate regimes.

Nanomaterials for environmental studies: Classification, reference material issues, and strategies for physico-chemical characterisation

International Nuclear Information System (INIS)

Stone, Vicki; Nowack, Bernd; Baun, Anders; Brink, Nico van den; Kammer, Frank von der; Dusinska, Maria; Handy, Richard; Hankin, Steven; Hasselloev, Martin; Joner, Erik; Fernandes, Teresa F.

2010-01-01

NanoImpactNet is a European Commission Framework Programme 7 (FP7) funded project that provides a forum for the discussion of current opinions on nanomaterials in relation to human and environmental issues. In September 2008, in Zurich, a NanoImpactNet environmental workshop focused on three key questions: 1.What properties should be characterised for nanomaterials used in environmental and ecotoxicology studies? 2.What reference materials should be developed for use in environmental and ecotoxicological studies? 3.Is it possible to group different nanomaterials into categories for consideration in environmental studies? Such questions have been, at least partially, addressed by other projects/workshops especially in relation to human health effects. Such projects provide a useful basis on which this workshop was based, but in this particular case these questions were reformulated in order to focus specifically on environmental studies. The workshop participants, through a series of discussion and reflection sessions, generated the conclusions listed below. The physicochemical characterisation information identified as important for environmental studies included measures of aggregation/agglomeration/dispersability, size, dissolution (solubility), surface area, surface charge, surface chemistry/composition, with the assumption that chemical composition would already be known. There is a need to have test materials for ecotoxicology, and several substances are potentially useful, including TiO 2 nanoparticles, polystyrene beads labelled with fluorescent dyes, and silver nanoparticles. Some of these test materials could then be developed into certified reference materials over time. No clear consensus was reached regarding the classification of nanomaterials into categories to aid environmental studies, except that a chemistry-based classification system was a reasonable starting point, with some modifications. It was suggested, that additional work may be required

Nanomaterials for environmental studies: Classification, reference material issues, and strategies for physico-chemical characterisation

Energy Technology Data Exchange (ETDEWEB)

Stone, Vicki, E-mail: v.stone@napier.ac.uk [School of Life Sciences, Edinburgh Napier University, 10 Colinton Road, Edinburgh EH10 5DT (United Kingdom); Nowack, Bernd [Materials, Products and the Environment Group, Empa - Swiss Federal Laboratories for Materials Testing and Research, Lerchenfeldstrasse 5 CH - 9014 St. Gallen (Switzerland); Baun, Anders [Department of Environmental Engineering, Technical University of Denmark, NanoDTU, Building 113, 2800 Kgs. Lyngby (Denmark); Brink, Nico van den [Alterra, P.O. Box 47, 6700 AA Wageningen (Netherlands); Kammer, Frank von der [Department of Environmental Geosciences, Vienna University, Althanstrasse 14, Wien 1090 (Austria); Dusinska, Maria [Health Effects Laboratory, Centre for Ecological Economics, Norwegian Institute for Air Research (NILU), Instituttveien, 18, 2027 Kjeller (Norway); Handy, Richard [University of Plymouth, Davy Building, Drake Circus, Plymouth PL4 8AA (United Kingdom); Hankin, Steven [Institute of Occupational Medicine, Research Avenue North, Riccarton, Edinburgh EH14 4AP (United Kingdom); Hasselloev, Martin [Department of Chemistry, Environmental Nanoparticle Research Group, Goeteborg University, SE-412 96 Goeteborg (Sweden); Joner, Erik [Bioforsk Soil and Environment, Fredrik A Dahls vei 20, N-1432 Aas (Norway); Fernandes, Teresa F. [School of Life Sciences, Edinburgh Napier University, 10 Colinton Road, Edinburgh EH10 5DT (United Kingdom)

2010-03-01

NanoImpactNet is a European Commission Framework Programme 7 (FP7) funded project that provides a forum for the discussion of current opinions on nanomaterials in relation to human and environmental issues. In September 2008, in Zurich, a NanoImpactNet environmental workshop focused on three key questions: 1.What properties should be characterised for nanomaterials used in environmental and ecotoxicology studies? 2.What reference materials should be developed for use in environmental and ecotoxicological studies? 3.Is it possible to group different nanomaterials into categories for consideration in environmental studies? Such questions have been, at least partially, addressed by other projects/workshops especially in relation to human health effects. Such projects provide a useful basis on which this workshop was based, but in this particular case these questions were reformulated in order to focus specifically on environmental studies. The workshop participants, through a series of discussion and reflection sessions, generated the conclusions listed below. The physicochemical characterisation information identified as important for environmental studies included measures of aggregation/agglomeration/dispersability, size, dissolution (solubility), surface area, surface charge, surface chemistry/composition, with the assumption that chemical composition would already be known. There is a need to have test materials for ecotoxicology, and several substances are potentially useful, including TiO{sub 2} nanoparticles, polystyrene beads labelled with fluorescent dyes, and silver nanoparticles. Some of these test materials could then be developed into certified reference materials over time. No clear consensus was reached regarding the classification of nanomaterials into categories to aid environmental studies, except that a chemistry-based classification system was a reasonable starting point, with some modifications. It was suggested, that additional work may be

Electrochemical and SEM studies of tetra-ammine platinum (II) (Pt(NH3)4)(OH)2 solution

International Nuclear Information System (INIS)

Wan Jeffrey Basirun

2002-01-01

Electrochemical studies include cyclic voltammetry with microelectrodes were done on a solution of tetra-ammine platinum (II) (Pt(NH 3 ) 4 )(OH) 2 at pH 13 and showed that the electrochemical reduction of this compound was no different from the tetra-ammine platinum (II) (Pt(NH 3 ) 4 )(HPO 4 ) at pH 10.4. The solution was instable to high temperatures and results have shown that electroplating can be done at a limited temperature range for longer periods of time or at higher temperatures for short periods of time. Scanning electron microscopy was done on some of the constant current electrodeposited samples at high temperatures and result obtained was satisfactory. (Authors)

Electrochemical and spectroscopic studies of tungstencarbonyl complexes containing nitrogen and phosphorous ligands

Directory of Open Access Journals (Sweden)

Haddad Paula S.

2000-01-01

Full Text Available The present work deals with the synthesis, spectroscopic investigation and electrochemical behaviour of the compounds [W(CO4(bipy] (1, [W(CO3(bipy(dppm] (2 and [W(CO3(bipy(dppf] (3, bipy = 2,2'-bipyridine; dppm = bis(diphenylphosphinomethane; dppf = 1,1'-bis(diphenylphosphinoferrocene. The IR and 31P{¹H} NMR spectroscopic data have shown an octahedral coordination geometry for the tungsten atom with the diphosphines acting as monodentate ligands. The electrochemical behaviour of the complexes was investigated by cyclic voltammetry and controlled potential coulometry. Cyclic voltammograms have indicated that the compounds containing diphosphines ligands are more stable towards oxidation than compound (1.

CMOS Electrochemical Instrumentation for Biosensor Microsystems: A Review

Directory of Open Access Journals (Sweden)

Haitao Li

2016-12-01

Full Text Available Modern biosensors play a critical role in healthcare and have a quickly growing commercial market. Compared to traditional optical-based sensing, electrochemical biosensors are attractive due to superior performance in response time, cost, complexity and potential for miniaturization. To address the shortcomings of traditional benchtop electrochemical instruments, in recent years, many complementary metal oxide semiconductor (CMOS instrumentation circuits have been reported for electrochemical biosensors. This paper provides a review and analysis of CMOS electrochemical instrumentation circuits. First, important concepts in electrochemical sensing are presented from an instrumentation point of view. Then, electrochemical instrumentation circuits are organized into functional classes, and reported CMOS circuits are reviewed and analyzed to illuminate design options and performance tradeoffs. Finally, recent trends and challenges toward on-CMOS sensor integration that could enable highly miniaturized electrochemical biosensor microsystems are discussed. The information in the paper can guide next generation electrochemical sensor design.

Characterisation of exposure to non-ionising electromagnetic fields in the Spanish INMA birth cohort: study protocol.

Science.gov (United States)

Gallastegi, Mara; Guxens, Mònica; Jiménez-Zabala, Ana; Calvente, Irene; Fernández, Marta; Birks, Laura; Struchen, Benjamin; Vrijheid, Martine; Estarlich, Marisa; Fernández, Mariana F; Torrent, Maties; Ballester, Ferrán; Aurrekoetxea, Juan J; Ibarluzea, Jesús; Guerra, David; González, Julián; Röösli, Martin; Santa-Marina, Loreto

2016-02-18

Analysis of the association between exposure to electromagnetic fields of non-ionising radiation (EMF-NIR) and health in children and adolescents is hindered by the limited availability of data, mainly due to the difficulties on the exposure assessment. This study protocol describes the methodologies used for characterising exposure of children to EMF-NIR in the INMA (INfancia y Medio Ambiente- Environment and Childhood) Project, a prospective cohort study. Indirect (proximity to emission sources, questionnaires on sources use and geospatial propagation models) and direct methods (spot and fixed longer-term measurements and personal measurements) were conducted in order to assess exposure levels of study participants aged between 7 and 18 years old. The methodology used varies depending on the frequency of the EMF-NIR and the environment (homes, schools and parks). Questionnaires assessed the use of sources contributing both to Extremely Low Frequency (ELF) and Radiofrequency (RF) exposure levels. Geospatial propagation models (NISMap) are implemented and validated for environmental outdoor sources of RFs using spot measurements. Spot and fixed longer-term ELF and RF measurements were done in the environments where children spend most of the time. Moreover, personal measurements were taken in order to assess individual exposure to RF. The exposure data are used to explore their relationships with proximity and/or use of EMF-NIR sources. Characterisation of the EMF-NIR exposure by this combination of methods is intended to overcome problems encountered in other research. The assessment of exposure of INMA cohort children and adolescents living in different regions of Spain to the full frequency range of EMF-NIR extends the characterisation of environmental exposures in this cohort. Together with other data obtained in the project, on socioeconomic and family characteristics and development of the children and adolescents, this will enable to evaluate the complex

Characterisation of exposure to non-ionising electromagnetic fields in the Spanish INMA birth cohort: study protocol

Directory of Open Access Journals (Sweden)

Mara Gallastegi

2016-02-01

Full Text Available Abstract Background Analysis of the association between exposure to electromagnetic fields of non-ionising radiation (EMF-NIR and health in children and adolescents is hindered by the limited availability of data, mainly due to the difficulties on the exposure assessment. This study protocol describes the methodologies used for characterising exposure of children to EMF-NIR in the INMA (INfancia y Medio Ambiente- Environment and Childhood Project, a prospective cohort study. Methods/Design Indirect (proximity to emission sources, questionnaires on sources use and geospatial propagation models and direct methods (spot and fixed longer-term measurements and personal measurements were conducted in order to assess exposure levels of study participants aged between 7 and 18 years old. The methodology used varies depending on the frequency of the EMF-NIR and the environment (homes, schools and parks. Questionnaires assessed the use of sources contributing both to Extremely Low Frequency (ELF and Radiofrequency (RF exposure levels. Geospatial propagation models (NISMap are implemented and validated for environmental outdoor sources of RFs using spot measurements. Spot and fixed longer-term ELF and RF measurements were done in the environments where children spend most of the time. Moreover, personal measurements were taken in order to assess individual exposure to RF. The exposure data are used to explore their relationships with proximity and/or use of EMF-NIR sources. Discussion Characterisation of the EMF-NIR exposure by this combination of methods is intended to overcome problems encountered in other research. The assessment of exposure of INMA cohort children and adolescents living in different regions of Spain to the full frequency range of EMF-NIR extends the characterisation of environmental exposures in this cohort. Together with other data obtained in the project, on socioeconomic and family characteristics and development of the children

Quantitative characterisation of an engineering write-up using random walk analysis

Directory of Open Access Journals (Sweden)

Sunday A. Oke

2008-02-01

Full Text Available This contribution reports on the investigation of correlation properties in an English scientific text (engineering write-up by means of a random walk. Though the idea to use a random walk to characterise correlations is not new (it was used e.g. in the genome analysis and in the analysis of texts, a random walk approach to the analysis of an English scientific text is still far from being exploited in its full strength as demonstrated in this paper. A method of high-dimensional embedding is proposed. Case examples were drawn arbitrarily from four engineering write-ups (Ph.D. synopsis of three engineering departments in the Faculty of Technology, University of Ibadan, Nigeria. Thirteen additional analyses of non-engineering English texts were made and the results compared to the engineering English texts. Thus, a total of seventeen write-ups of eight Faculties and sixteen Departments of the University of Ibadan were considered. The characterising exponents which relate the average distance of random walkers away from a known starting position to the elapsed time steps were estimated for the seventeen cases according to the power law and in three different dimensional spaces. The average characteristic exponent obtained for the seventeen cases and over three different dimensional spaces studied was 1.42 to 2-decimal with a minimum and a maximum coefficient of determination (R2 of 0.9495 and 0.9994 respectively. This is found to be 284% of the average characterising exponent value (0.5, as supported by the literature for random walkers based on the pseudo-random number generator. The average characteristic exponent obtained for the four cases that were engineering-based and over the three different dimensional studied spaces was 1.41 to 2-decimal (closer by 99.3% to 1.42 with a minimum and a maximum coefficient of determination (R2 of 0.9507 and 0.9974 respectively. This is found to be 282% of the average characterising exponent value (0.5, as

Defining Jazz Revisited - Taking a social constructionist approach to the characterisation of jazz

DEFF Research Database (Denmark)

Høyer, Ole Izard

2017-01-01

the concept of jazz from a social constructionist perspective and examines how constructions of a genre formation of jazz are characterised by ideas about the social. It is argued that ‘characterisations of jazz’ are central to such genre-definitions and are as tightly bound to social context......This article reconsiders the definition of jazz as a case study in relation to how a musical genre is constituted through narratives of culture and identity in musical culture. Rethinking the definition of jazz as a way of characterisation through a social constructionist approach, this article...

Thermophysical and Electrochemical Properties of Ethereal Functionalised Cyclic Alkylammonium-based Ionic Liquids as Potential Electrolytes for Electrochemical Applications.

Science.gov (United States)

Neale, Alex R; Murphy, Sinead; Goodrich, Peter; Hardacre, Christopher; Jacquemin, Johan

2017-08-05

A series of hydrophobic room temperature ionic liquids (ILs) based on ethereal functionalised pyrrolidinium, piperidinium and azepanium cations bearing the bis[(trifluoromethyl)sulfonyl]imide, [TFSI] - , anion were synthesized and characterized. Their physicochemical properties such as density, viscosity and electrolytic conductivity, and thermal properties including phase transition behaviour and decomposition temperature have been measured. All of the ILs showed low melting point, low viscosity and good conductivity and the latter properties have been discussed in terms of the IL fragility, an important electrolyte feature of the transport properties of glass-forming ILs. Furthermore, the studied [TFSI] - -based ILs generally exhibit good electrochemical stabilities and, by coupling electrochemical experiments and DFT calculations, the effect of ether functionalisation at the IL cation on the electrochemical stability of the IL is discussed. Preliminary investigations into the Li-redox chemistry at a Cu working electrode are also reported as a function of ether-functionality within the pyrrolidinium-based IL family. Overall, the results show that these ionic liquids are suitable for electrochemical devices such as battery systems, fuel cells or supercapacitors. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Electrochemical development of particle tracks in CR-39 polymer dosimeter

International Nuclear Information System (INIS)

Hadlock, D.E.; Parkhurst, M.A.; Yang, C.S.; Groeger, J.; Johnson, J.R.; Huang, S.J.

1985-09-01

Electrochemical etching of CR-39 polymeric track etch neutron detectors results in proton-recoil tracks can be distinguished from background tracks much better than tracks developed solely by chemical etching. A newly designed and constructed electrochemical etching apparatus allows large numbers of dosimeters to be processed simultaneously with consistent results. Many processing systems have been developed for chemical and electrochemical etching of the track etch dosimeters. Three systems specifically show great promise and are being studied extensively

The use of anions with sulfate function in electrolyte for lithium battery. Study of transport mechanism; Utilisation d'anions a fonction sulfate dans des electrolytes pour batterie au lithium. Etude des mecanismes de transport

Energy Technology Data Exchange (ETDEWEB)

Chauvin, Ch.

2005-05-15

Lithium salts based on oligo-ether sulfate were synthesized and characterised. They incorporate oxy-ethylene units which enable the lithium cation salvation and, potentially, their use as ionic liquids. Their properties as lithium salts dissolved in liquid or polymer electrolytes were evaluated. Their electrochemical and thermal stabilities are sufficient for lithium battery application. Due to their weak dissociation in POE, their conductivities are fairly low. On the other hand, they have high cationic transference numbers. In mixture with usual salts as LiTFSI, they provide a good compromise between conductivities/transference number/cost. The second part of this study deals with the synthesis and characterisation of an ionomer with sulfate function and polyether backbone. The electrochemical, physical and chemical properties of this material show that it could be used as polymer electrolyte. Its potential as cross-linked gelled polymer electrolyte is outstanding. Structural analyses on an ionomeric monocrystal have been corroborated with quantum chemistry calculations. (author)

Electrochemical solar energy conversion

International Nuclear Information System (INIS)

Gerischer, H.

1991-01-01

The principles of solar energy conversion in photoelectrochemical cells are briefly reviewed. Cells for the generation of electric power and for energy storage in form of electrochemical energy are described. These systems are compared with solid state photovoltaic devices, and the inherent difficulties for the operation of the electrochemical systems are analyzed. (author). 28 refs, 10 figs

Electrochemical characterization of praseodymia doped zircon. Catalytic effect on the electrochemical reduction of molecular oxygen in polar organic solvents

Energy Technology Data Exchange (ETDEWEB)

Domenech, Antonio, E-mail: antonio.domenech@uv.es [Departament de Quimica Analitica, Universitat de Valencia, Dr. Moliner, 50, 46100 Burjassot, Valencia (Spain); Montoya, Noemi; Alarcon, Javier [Departament de Quimica Inorganica, Universitat de Valencia, Dr. Moliner, 50, 46100 Burjassot, Valencia (Spain)

2011-08-01

Highlights: > Electrochemical characterization of Pr centers in praseodymia-doped zircon. > Study of the catalytic effect on the reduction of peroxide radical anion in nonaqueous solvents. > Assessment of non-uniform distribution of Pr centers in the zircon grains. - Abstract: The voltammetry of microparticles and scanning electrochemical microscopy methodologies are applied to characterize praseodymium centers in praseodymia-doped zircon (Pr{sub x}Zr{sub (1-y)}Si{sub (1-z)}O{sub 4}; y + z = x; 0.02 < x < 0.10) specimens prepared via sol-gel synthetic routes. In contact with aqueous electrolytes, two overlapping Pr-centered cathodic processes, attributable to the Pr (IV) to Pr (III) reduction of Pr centers in different sites are obtained. In water-containing, air-saturated acetone and DMSO solutions as solvent, Pr{sub x}Zr{sub (1-y)}Si{sub (1-z)}O{sub 4} materials produce a significant catalytic effect on the electrochemical reduction of peroxide radical anion electrochemically generated. These electrochemical features denote that most of the Pr centers are originally in its 4+ oxidation state in the parent Pr{sub x}Zr{sub (1-y)}Si{sub (1-z)}O{sub 4} specimens. The variation of the catalytic performance of such specimens with potential scan rate, water concentration and Pr loading suggests that Pr is not uniformly distributed within the zircon grains, being concentrated in the outer region of such grains.

Electrochemical characterization of hydrogels for biomimetic applications

DEFF Research Database (Denmark)

Peláez, L.; Romero, V.; Escalera, S.

2011-01-01

) or a photoinitiator (P) to encapsulate and stabilize biomimetic membranes for novel separation technologies or biosensor applications. In this paper, we have investigated the electrochemical properties of the hydrogels used for membrane encapsulation. Specifically, we studied the crosslinked hydrogels by using...... electrochemical impedance spectroscopy (EIS), and we demonstrated that chemically crosslinked hydrogels had lower values for the effective electrical resistance and higher values for the electrical capacitance compared with hydrogels with photoinitiated crosslinking. Transport numbers were obtained using......〉 and 〈Pw〉 values than PEG‐1000‐DMA‐P and PEG‐400‐DA‐P hydrogels. In conclusion, our results show that hydrogel electrochemical properties can be controlled by the choice of polymer and type of crosslinking used and that their water and salt permeability properties are congruent with the use of hydrogels...

Characterisation of anisotropic etching in KOH using network etch rate function model: influence of an applied potential in terms of microscopic properties

International Nuclear Information System (INIS)

Nguyen, Q D; Elwenspoek, M

2006-01-01

Using the network etch rate function model, the anisotropic etch rate of p-type single crystal silicon was characterised in terms of microscopic properties including step velocity, step and terrace roughening. The anisotropic etch rate data needed have been obtained using a combination of 2 wagon wheel patterns on different substrate and 1 offset trench pattern. Using this procedure the influence of an applied potential has been investigated in terms of microscopic properties. Model parameter trends show a good correlation with chemical/electrochemical reaction mechanism and mono- and dihydride terminated steps reactivity difference. Results also indicate a minimum in (111) terrace roughening which results in a peak in anisotropic ratio at the non-OCP applied potential of -1250 mV vs OCP

Characterization of Electrochemically Generated Silver

Science.gov (United States)

Adam, Niklas; Martinez, James; Carrier, Chris

2014-01-01

Silver biocide offers a potential advantage over iodine, the current state of the art in US spacecraft disinfection technology, in that silver can be safely consumed by the crew. Low concentrations of silver (Silver does not require hardware to remove it from a water system, and therefore can provide a simpler means for disinfecting water. The Russian segment of the International Space Station has utilized an electrochemically generated silver solution, which is colloidal in nature. To be able to reliably provide a silver biocide to drinking water by electrochemical means would reduce mass required for removing another biocide such as iodine from the water. This would also aid in crew time required to replace iodine removal cartridges. Future long term missions would benefit from electrochemically produced silver as the biocide could be produced on demand and requires only a small concentration to be effective. Since it can also be consumed safely, there is less mass in removal hardware and little consumables required for production. The goal of this project initially is to understand the nature of the electrochemically produced silver, the particle sizes produced by the electrochemical cell and the effect that voltage adjustment has on the particle size. In literature, it has been documented that dissolved oxygen and pH have an effect on the ionization of the electrochemical silver so those parameters would be measured and possibly adjusted to understand their effect on the silver.

Concatenation of electrochemical grafting with chemical or electrochemical modification for preparing electrodes with specific surface functionality

International Nuclear Information System (INIS)

Verma, Pallavi; Maire, Pascal; Novak, Petr

2011-01-01

Surface modified electrodes are used in electro-analysis, electro-catalysis, sensors, biomedical applications, etc. and could also be used in batteries. The properties of modified electrodes are determined by the surface functionality. Therefore, the steps involved in the surface modification of the electrodes to obtain specific functionality are of prime importance. We illustrate here bridging of two routes of surface modifications namely electrochemical grafting, and chemical or electrochemical reduction. First, by electrochemical grafting an organic moiety is covalently immobilized on the surface. Then, either by chemical or by electrochemical route the terminal functional group of the grafted moiety is transformed. Using the former route we prepared lithium alkyl carbonate (-O(CH 2 ) 3 OCO 2 Li) modified carbon with potential applications in batteries, and employing the latter we prepared phenyl hydroxyl amine (-C 6 H 4 NHOH) modified carbon which may find application in biosensors. Benzyl alcohol (-C 6 H 4 CH 2 OH) modified carbon was prepared by both chemical as well as electrochemical route. We report combinations of conjugating the two steps of surface modifications and show how the optimal route of terminal functional group modification depends on the chemical nature of the moiety attached to the surface in the electrochemical grafting step.

Concatenation of electrochemical grafting with chemical or electrochemical modification for preparing electrodes with specific surface functionality

Energy Technology Data Exchange (ETDEWEB)

Verma, Pallavi; Maire, Pascal [Paul Scherrer Institut, Electrochemistry Laboratory, Section Electrochemical Energy Storage, CH-5232 Villigen PSI (Switzerland); Novak, Petr, E-mail: petr.novak@psi.c [Paul Scherrer Institut, Electrochemistry Laboratory, Section Electrochemical Energy Storage, CH-5232 Villigen PSI (Switzerland)

2011-04-01

Surface modified electrodes are used in electro-analysis, electro-catalysis, sensors, biomedical applications, etc. and could also be used in batteries. The properties of modified electrodes are determined by the surface functionality. Therefore, the steps involved in the surface modification of the electrodes to obtain specific functionality are of prime importance. We illustrate here bridging of two routes of surface modifications namely electrochemical grafting, and chemical or electrochemical reduction. First, by electrochemical grafting an organic moiety is covalently immobilized on the surface. Then, either by chemical or by electrochemical route the terminal functional group of the grafted moiety is transformed. Using the former route we prepared lithium alkyl carbonate (-O(CH{sub 2}){sub 3}OCO{sub 2}Li) modified carbon with potential applications in batteries, and employing the latter we prepared phenyl hydroxyl amine (-C{sub 6}H{sub 4}NHOH) modified carbon which may find application in biosensors. Benzyl alcohol (-C{sub 6}H{sub 4}CH{sub 2}OH) modified carbon was prepared by both chemical as well as electrochemical route. We report combinations of conjugating the two steps of surface modifications and show how the optimal route of terminal functional group modification depends on the chemical nature of the moiety attached to the surface in the electrochemical grafting step.

Bussing Structure In An Electrochemical Cell

Science.gov (United States)

Romero, Antonio L.

2001-06-12

A bussing structure for bussing current within an electrochemical cell. The bussing structure includes a first plate and a second plate, each having a central aperture therein. Current collection tabs, extending from an electrode stack in the electrochemical cell, extend through the central aperture in the first plate, and are then sandwiched between the first plate and second plate. The second plate is then connected to a terminal on the outside of the case of the electrochemical cell. Each of the first and second plates includes a second aperture which is positioned beneath a safety vent in the case of the electrochemical cell to promote turbulent flow of gasses through the vent upon its opening. The second plate also includes protrusions for spacing the bussing structure from the case, as well as plateaus for connecting the bussing structure to the terminal on the case of the electrochemical cell.

Destructive impact of molecular noise on nanoscale electrochemical oscillators

Science.gov (United States)

Cosi, Filippo G.; Krischer, Katharina

2017-06-01

We study the loss of coherence of electrochemical oscillations on meso- and nanosized electrodes with numeric simulations of the electrochemical master equation for a prototypical electrochemical oscillator, the hydrogen peroxide reduction on Pt electrodes in the presence of halides. On nanoelectrodes, the electrode potential changes whenever a stochastic electron-transfer event takes place. Electrochemical reaction rate coefficients depend exponentially on the electrode potential and become thus fluctuating quantities as well. Therefore, also the transition rates between system states become time-dependent which constitutes a fundamental difference to purely chemical nanoscale oscillators. Three implications are demonstrated: (a) oscillations and steady states shift in phase space with decreasing system size, thereby also decreasing considerably the oscillating parameter regions; (b) the minimal number of molecules necessary to support correlated oscillations is more than 10 times as large as for nanoscale chemical oscillators; (c) the relation between correlation time and variance of the period of the oscillations predicted for chemical oscillators in the weak noise limit is only fulfilled in a very restricted parameter range for the electrochemical nano-oscillator.

A Comprehensive Pitting Study of High Velocity Oxygen Fuel Inconel 625 Coating by Using Electrochemical Testing Techniques

Science.gov (United States)

Niaz, Akbar; Khan, Sajid Ullah

2016-01-01

In the present work, Inconel 625 was coated on a mild steel substrate using a high velocity oxygen fuel coating process. The pitting propensity of the coating was tested by using open circuit potential versus time, potentiodynamic polarization, electrochemical potentiokinetic reactivation, and scanning electrochemical microscopy. The pitting propensity of the coating was compared with bulk Inconel 625 alloy. The results confirmed that there were regions of different electrochemical activities on the coating which have caused pitting corrosion.

Electrochemical activation of Li2MnO3 at elevated temperature investigated by in situ Raman microscopy

International Nuclear Information System (INIS)

Lanz, Patrick; Villevieille, Claire; Novák, Petr

2013-01-01

Layered-layered oxides of the type xLi 2 MnO 3 ·(1 − x)LiMO 2 (M = Mn, Ni, Co) have been postulated to contain Li 2 MnO 3 domains which, upon electrochemical activation, give rise to a characteristic potential plateau at 4.5 V vs. Li + /Li. To improve our understanding of the complex reaction mechanisms at play, we applied in situ Raman microscopy to investigate the constituent Li 2 MnO 3 . Li 2 MnO 3 synthesised via a two-step solid-state reaction was characterised by scanning electron microscopy and X-ray diffraction. Preliminary electrochemical tests and ex situ Raman microscopy showed the need for elevated temperatures to achieve activation. For the first time, in situ Raman microscopy (at 50 °C) confirmed the activation of Li 2 MnO 3 . The main signal at 615 cm −1 shifted to higher wavenumbers upon charging. After reaching 4.4 V vs. Li + /Li, this shift grew significantly, which is in good agreement with the onset of the potential plateau in both Li 2 MnO 3 and xLi 2 MnO 3 ·(1 − x)LiMO 2 , and is assigned to the partial formation of a spinel-like phase

Database characterisation of HEP applications

International Nuclear Information System (INIS)

Piorkowski, Mariusz; Grancher, Eric; Topurov, Anton

2012-01-01

Oracle-based database applications underpin many key aspects of operations for both the LHC accelerator and the LHC experiments. In addition to the overall performance, the predictability of the response is a key requirement to ensure smooth operations and delivering predictability requires understanding the applications from the ground up. Fortunately, database management systems provide several tools to check, measure, analyse and gather useful information. We present our experiences characterising the performance of several typical HEP database applications performance characterisations that were used to deliver improved predictability and scalability as well as for optimising the hardware platform choice as we migrated to new hardware and Oracle 11g.

Electrochemical reaction rates in a dye-sensitised solar cell - the iodide/tri-iodide redox system

DEFF Research Database (Denmark)

Bay, L.; West, K.; Winther-Jensen, B.

2006-01-01

The electrochemical reaction rate of the redox couple iodide/tri-iodide in acetonitrile is characterised by impedance spectroscopy. Different electrode materials relevant for the function of dye-sensitised solar cells (DSSC) are investigated. Preferably, the reaction with the iodide....../tri-iodide couple should be fast at the counter electrode, i.e. this electrode must have a high catalytic activity towards the redox couple, and the same reaction must be slow on the photo electrode. The catalytic activity is investigated for platinum, poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPy......), and polyaniline (PANI)-all deposited onto fluorine-doped tin oxide (FTO) glass. Both Pt and PEDOT are found to have sufficiently high catalytic activities for practical use as counter electrodes in DSSC. The reaction resistance on FTO and anatase confirmed the beneficial effect of a compact anatase layer on top...

Electrochemical reaction rates in a dye sentisised solar cell - the iodide/tri-iodide redox system

DEFF Research Database (Denmark)

Bay, Lasse; West, Keld; Winter-Jensen, Bjørn

2006-01-01

The electrochemical reaction rate of the redox couple iodide / tri-iodide in acetonitrile is characterised by impedance spectroscopy. Different electrode materials relevant for the function of dye-sensitised solar cells (DSSC) are investigated. Preferably, the reaction with the iodide / tri......-iodide couple should be fast at the counter electrode, i.e. this electrode must have a high catalytic activity towards the redox couple, and the same reaction must be slow on the photo electrode. The catalytic activity is investigated for platinum, poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPy......), and polyaniline (PANI) - all deposited onto fluorine doped tin oxide (FTO) glass. Both Pt and PEDOT are found to have sufficiently high catalytic activities for practical use as counter electrode in DSSC. The reaction resistance on FTO and anatase confirmed the beneficial effect of a compact anatase layer on top...

Characterisation and concentration profile of aluminium during ...

African Journals Online (AJOL)

An aluminium(Al) characterisation study was conducted at a surface water treatment plant (Buffalo Pound Water Treatment Plant (BPWTP) in Moose Jaw, Saskatchewan, Canada) to understand better the effect of alum coagulant on various Al fractions. The raw water source for BPWTP is Buffalo Pound Lake water. The Al ...

Characterisation of Gliclazide-PEG 8000 Solid Dispersions

African Journals Online (AJOL)

Erah

Purpose: The aim of the present study was to characterise gliclazide solid dispersions (SDs) ... Results: The solubility of gliclazide increased with increasing amount of PEG 8000 in aqueous medium. ... FTIR analysis demonstrated the absence of well-defined gliclazide - PEG 8000 .... voltage of 35 kV and 20 mA current. The.

Characterisation of childhood and adolescence accidental fatalities ...

African Journals Online (AJOL)

Background: Accidental death in childhood and adolescence is posing a public health problem in Nigeria, as most of these deaths were not caused by the victims. There is need to research into the pattern and circumstances surrounding the death. Aim: To characterise and study accidental deaths in childhood and ...

Electrochemical ion separation in molten salts

Science.gov (United States)

Spoerke, Erik David; Ihlefeld, Jon; Waldrip, Karen; Wheeler, Jill S.; Brown-Shaklee, Harlan James; Small, Leo J.; Wheeler, David R.

2017-12-19

A purification method that uses ion-selective ceramics to electrochemically filter waste products from a molten salt. The electrochemical method uses ion-conducting ceramics that are selective for the molten salt cations desired in the final purified melt, and selective against any contaminant ions. The method can be integrated into a slightly modified version of the electrochemical framework currently used in pyroprocessing of nuclear wastes.

Study of the degradation of liquid-organic radioactive wastes by electrochemical methods

International Nuclear Information System (INIS)

Hernandez A, J. I.

2015-01-01

In this study degradation studies were performed on blank samples, in which two electrochemical cells with different electrodes were used, the first is constituted by mesh electrodes Ti/Ir-Ta/Ti and the second by rod electrodes Ti/Ddb, using as reference an electrolytic medium of scintillation liquid and scintillation liquid more water, applying different potentials ranging from 1 to 25 V. After obtaining the benchmarks, the treatment was applied to samples containing organic liquid radioactive waste, in this case a short half-life radioisotope as Sulfur-35, the degradation characterization of organic compounds was performed in infrared spectrometry. (Author)

Concentric-Electrode Organic Electrochemical Transistors: Case Study for Selective Hydrazine Sensing

Directory of Open Access Journals (Sweden)

Sébastien Pecqueur

2017-03-01

Full Text Available We report on hydrazine-sensing organic electrochemical transistors (OECTs with a design consisting of concentric annular electrodes. The design engineering of these OECTs was motivated by the great potential of using OECT sensing arrays in fields such as bioelectronics. In this work, poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate (PEDOT:PSS-based OECTs have been studied as aqueous sensors that are specifically sensitive to the lethal hydrazine molecule. These amperometric sensors have many relevant features for the development of hydrazine sensors, such as a sensitivity down to 10−5 M of hydrazine in water, an order of magnitude higher selectivity for hydrazine than for nine other water-soluble common analytes, the capability to entirely recover its base signal after water flushing, and a very low operation voltage. The specificity for hydrazine to be sensed by our OECTs is caused by its catalytic oxidation at the gate electrode, and enables an increase in the output current modulation of the devices. This has permitted the device-geometry study of the whole series of 80 micrometric OECT devices with sub-20-nm PEDOT:PSS layers, channel lengths down to 1 µm, and a specific device geometry of coplanar and concentric electrodes. The numerous geometries unravel new aspects of the OECT mechanisms governing the electrochemical sensing behaviours of the device—more particularly the effect of the contacts which are inherent at the micro-scale. By lowering the device cross-talk, micrometric gate-integrated radial OECTs shall contribute to the diminishing of the readout invasiveness and therefore further promote the development of OECT biosensors.

Study of the aqueous synthesis, optical and electrochemical characterization of alloyed Zn{sub x}Cd{sub 1-x}Te nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Matos, Charlene Regina Santos [Postgraduate Program in Materials Science and Engineering, Federal University of Sergipe, São Cristóvão, SE (Brazil); Candido, Luan P.M.; Souza, Helio Oliveira [Department of Chemistry, Federal University of Sergipe, São Cristóvão, SE (Brazil); Pereira da Costa, Luiz [Institute of Technology and Research (ITP), Tiradentes University, Aracaju, SE (Brazil); Sussuchi, Eliana Midori [Department of Chemistry, Federal University of Sergipe, São Cristóvão, SE (Brazil); Gimenez, Iara F., E-mail: gimenez@ufs.br [Postgraduate Program in Materials Science and Engineering, Federal University of Sergipe, São Cristóvão, SE (Brazil); Department of Chemistry, Federal University of Sergipe, São Cristóvão, SE (Brazil); Postgraduate Program in Chemistry, Federal University of Sergipe, São Cristóvão, SE (Brazil)

2016-08-01

The effects of experimental factors such as initial reaction pH, capping ligand, and heating method on the optical and electrochemical properties of aqueous alloyed Zn{sub x}Cd{sub 1-x}Te nanocrystals were evaluated. Here the type of capping ligand (glutathione GSH and 3-mercaptopropionic acid MPA) was found to be the most significant factor in controlling the range of photoluminescence emission. Also a pronounced pH effect on the emission wavelength has been verified in the presence of GSH, in contrast to MPA for which only a minor pH effect was observed. The heating method (microwave or hydrothermal) was found to be irrelevant for the emission wavelength at the conditions studied. The electrochemical characterization in aqueous medium (cyclic voltammetry and differential pulse voltammetry) evidenced a good correlation between electrochemical and optical band gap values and allowed estimation of band edge positions. - Highlights: • ZnCdTe quantum dots were obtained by aqueous synthesis. • Nature of capping ligand was the most relevant factor. • Optical and electrochemical band gaps were well correlated.

Study of electrochemical corrosion parameters in the detection of fission fragments in solid state trace detectors (SSTD)

International Nuclear Information System (INIS)

Silva Oliveira, S. da; Rogers, J.D.

1980-01-01

The basic properties of the electrochemical corrosion method, for the Makrofol E plastic, irradiated with fission fragments from a 252 Cf source were studied and discussed in this paper. (A.C.A.S.) [pt

Contribution to the electrochemical study of corrosion in low-conductivity environments. Application to the study of the behaviour of austenitic stainless steels in concentrated solutions of acetic acid

International Nuclear Information System (INIS)

Chechirlian, Serge

1989-01-01

As the use of conventional electrochemical methods to study metal and alloy corrosion in concentrated solutions of acetic acid is challenged by difficulties due the low conductivity of these environments, the first part of this research thesis proposes a critical, theoretical and experimental study of these difficulties. It notably evokes the use of electrochemical impedance techniques, the different compensation devices and means of correction of the ohmic voltage drop, and artefacts used during high frequency impedance measurements in lesser conductive solutions. The second part addresses the characterization of the corrosion behaviour of austenitic stainless steels in a concentrated acetic acid at 25 and 95 degrees C. Electrochemical techniques are coupled with analytical methods (solution analysis, sample surface analysis after corrosion tests). The roles of molybdenum as alloying element, of dissolved oxygen, of impurities (sulfites) or of formic acid additions are studied and discussed [fr

Ordered mesoporous carbon for electrochemical sensing: A review

Energy Technology Data Exchange (ETDEWEB)

Ndamanisha, Jean Chrysostome [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Universite du Burundi, Institut de pedagogie appliquee, B.P. 5223, Bujumbura (Burundi); Guo Liping, E-mail: guolp078@nenu.edu.cn [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China)

2012-10-17

Highlights: Black-Right-Pointing-Pointer The preparation and functionalization of ordered mesoporous carbon. Black-Right-Pointing-Pointer Their applications as electrochemical sensors with high electrocatalytic activity. Black-Right-Pointing-Pointer A promising electrode material based on its interesting properties. - Abstract: With its well-ordered pore structure, high specific surface area and tunable pore diameters in the mesopore range, ordered mesoporous carbon (OMC) is suitable for applications in catalysis and sensing. We report recent applications of OMC in electrochemical sensors and biosensors. After a brief description of the electrochemical properties, the functionalization of the OMC for improvement of the electrocatalytic properties is then presented. We show how the ordered mesostructure of OMC is very important in those applications. The high density of edge plane-like defective sites (EDSs), oxygen-containing groups and a large surface area on OMC may provide many favorable sites for electron transfer to compounds, which makes OMC a potential novel material for an investigation of the electrochemical behavior of substances. Moreover, the structural capabilities of OMC at the scale of a few nanometers agree with immobilization of other electrocataytic substances. Interesting properties of this material may open up a new approach to study the electrochemical determination of other biomolecules.

Nitrogen-Doped Three Dimensional Graphene for Electrochemical Sensing.

Science.gov (United States)

Yan, Jing; Chen, Ruwen; Liang, Qionglin; Li, Jinghong

2015-07-01

The rational assembly and doping of graphene play an crucial role in the improvement of electrochemical performance for analytical applications. Covalent assembly of graphene into ordered hierarchical structure provides an interconnected three dimensional conductive network and large specific area beneficial to electrolyte transfer on the electrode surface. Chemical doping with heteroatom is a powerful tool to intrinsically modify the electronic properties of graphene due to the increased free charge-carrier densities. By incorporating covalent assembly and nitrogen doping strategy, a novel nitrogen doped three dimensional reduced graphene oxide nanostructure (3D-N-RGO) was developed with synergetic enhancement in electrochemical behaviors. The as prepared 3D-N-RGO was further applied for catechol detection by differential pulse voltammetry. It exhibits much higher electrocatalytic activity towards catechol with increased peak current and decreased potential difference between the oxidation and reduction peaks. Owing to the improved electro-chemical properties, the response of the electrochemical sensor varies linearly with the catechol concentrations ranging from 5 µM to 100 µM with a detection limit of 2 µM (S/N = 3). This work is promising to open new possibilities in the study of novel graphene nanostructure and promote its potential electrochemical applications.

Electrochemical Impedance Study of Reduction Kinetics of the Pesticide Vinclozoline

Czech Academy of Sciences Publication Activity Database

Pospíšil, Lubomír; Sokolová, Romana; Colombini, M. P.; Giannarelli, S.; Fuoco, R.

2000-01-01

Roč. 67, - (2000), s. 305-312 ISSN 0026-265X R&D Projects: GA MŠk OC D15.10; GA ČR GA203/97/1048 Institutional research plan: CEZ:AV0Z4040901 Keywords : electrochemical impedance * pesticide s * vinclozoline Subject RIV: CG - Electrochemistry Impact factor: 0.884, year: 2000

Combined rock-physical modelling and seismic inversion techniques for characterisation of stacked sandstone reservoir

NARCIS (Netherlands)

Justiniano, A.; Jaya, Y.; Diephuis, G.; Veenhof, R.; Pringle, T.

2015-01-01

The objective of the study is to characterise the Triassic massive stacked sandstone deposits of the Main Buntsandstein Subgroup at Block Q16 located in the West Netherlands Basin. The characterisation was carried out through combining rock-physics modelling and seismic inversion techniques. The

Reactivity study of silicon electrode modified by grafting using electrochemical reduction of diazonium salts

International Nuclear Information System (INIS)

Kaiber, A.; Cherkkaoui, M.; Chazalviel, J.N.

2015-01-01

The use of the hydrogenated surface of silicon is hampered by its chemical instability by surface oxidation. The researchers have attempted to modify this surface by direct grafting through the establishment of covalent silicon-carbon bonds from the reaction of chemical species on the surface. Different grafting methods can be implemented for the preparation of grafted surfaces. The choice of an electrochemical reaction allows fast grafting from the hydrogenated surface. We studied the formation of a phenyl layer by electrochemical reduction of aryl diazonium salts (BF4-,+N2-ph-OCH3) on a p-Si-H (111) electrode in an aqueous medium (0.05M H/sub 2/SO/sub 4/ + 0.05M HF). The grafting of an organic layer by reduction is confirmed by the observation of a cyclic voltammetry peak around -0.3V/SCE. In-situ infrared spectroscopy (IR) analysis allows to identify the chemical functions present on the grafted surface, allowing a direct monitoring of the grafting reaction. (author)

Electrochemical Study of Esculetin Nitration by Digital Simulation of Cyclic Voltammograms

Directory of Open Access Journals (Sweden)

Lida Khalafi

2013-01-01

Full Text Available The reaction of electrochemically generated o-quinones from oxidation of esculetin as Michael acceptor with nitrite ion as nucleophile has been studied using cyclic voltammetry. The reaction mechanism is believed to be EC, including oxidation of catechol moiety of esculetin followed by Michael addition of nitrite ion. The observed homogeneous rate constants (obs for reactions were estimated by comparing the experimental voltammetric responses with the digitally simulated results based on the proposed mechanism. Also the effects of pH and nucleophile concentration on voltammetric behavior and the rate constants of chemical reactions were described.

Characterisation of contaminated metals using an advanced statistical toolbox - Geostatistical characterisation of contaminated metals: methodology and illustrations

International Nuclear Information System (INIS)

Larsson, Arne; Lidar, Per; Desnoyers, Yvon

2014-01-01

Radiological characterisation plays an important role in the process to recycle contaminated or potentially contaminated metals. It is a platform for planning, identification of the extent and nature of contamination, assessing potential risk impacts, cost estimation, radiation protection, management of material arising from decommissioning as well as for the release of the materials as well as the disposal of the generated secondary waste as radioactive waste. Key issues in radiological characterisation are identification of objectives, development of a measurement and sampling strategy (probabilistic, judgmental or a combination thereof), knowledge management, traceability, recording and processing of obtained information. By applying advanced combination of statistical and geostatistical in the concept better performance can be achieved at a lower cost. This paper will describe the benefits with the usage of the available methods in the different stages of the characterisation, treatment and clearance processes aiming for reliable results in line with the data quality objectives. (authors)

Capsid protein oxidation in feline calicivirus using an electrochemical inactivation treatment

Energy Technology Data Exchange (ETDEWEB)

Shionoiri, Nozomi; Nogariya, Osamu; Tanaka, Masayoshi; Matsunaga, Tadashi; Tanaka, Tsuyoshi, E-mail: tsuyo@cc.tuat.ac.jp

2015-02-11

Highlights: • Feline calicivirus was inactivated electrochemically by a factor of >5 log. • The electrochemical treatment was performed at 0.9 V (vs. Ag/AgCl) for 15 min. • Electrochemical treatment caused oxidation of viral proteins. • Oxidation of viral proteins can lead to loss of viral structural integrity. - Abstract: Pathogenic viral infections are an international public health concern, and viral disinfection has received increasing attention. Electrochemical treatment has been used for treatment of water contaminated by bacteria for several decades, and although in recent years several reports have investigated viral inactivation kinetics, the mode of action of viral inactivation by electrochemical treatment remains unclear. Here, we demonstrated the inactivation of feline calicivirus (FCV), a surrogate for human noroviruses, by electrochemical treatment in a developed flow-cell equipped with a screen-printed electrode. The viral infectivity titer was reduced by over 5 orders of magnitude after 15 min of treatment at 0.9 V vs. Ag/AgCl. Proteomic study of electrochemically inactivated virus revealed oxidation of peptides located in the viral particles; oxidation was not observed in the non-treated sample. Furthermore, transmission electron microscopy revealed that viral particles in the treated sample had irregular structures. These results suggest that electrochemical treatment inactivates FCV via oxidation of peptides in the structural region, causing structural deformation of virus particles. This first report of viral protein damage through electrochemical treatment will contribute to broadening the understanding of viral inactivation mechanisms.

Synthesis, Characterization, and Electrochemical Properties of Polyaniline Thin Films

Science.gov (United States)

Rami, Soukaina

Conjugated polymers have been used in various applications (battery, supercapacitor, electromagnetic shielding, chemical sensor, biosensor, nanocomposite, light-emitting-diode, electrochromic display etc.) due to their excellent conductivity, electrochemical and optical properties, and low cost. Polyaniline has attracted the researchers from all disciplines of science, engineering, and industry due to its redox properties, environmental stability, conductivity, and optical properties. Moreover, it is a polymer with fast electroactive switching and reversible properties displayed at low potential, which is an important feature in many applications. The thin oriented polyaniline films have been fabricated using self-assembly, Langmuir-Blodgett, in-situ self-assembly, layer-by-layer, and electrochemical technique. The focus of this thesis is to synthesize and characterize polyaniline thin films with and without dyes. Also, the purpose of this thesis is to find the fastest electroactive switching PANI electrode in different electrolytic medium by studying their electrochemical properties. These films were fabricated using two deposition techniques: in-situ self-assembly and electrochemical deposition. The characterization of these films was done using techniques such as Fourier Transform Infrared Spectroscopy (FTIR), UV-spectroscopy, Scanning Electron Microscope (SEM), and X-Ray Diffraction (XRD). FTIR and UV-spectroscopy showed similar results in the structure of the polyaniline films. However, for the dye incorporated films, since there was an addition in the synthesis of the material, peak locations shifted, and new peaks corresponding to these materials appeared. The 1 layer PANI showed compact film morphology, comparing to other PANI films, which displayed a fiber-like structure. Finally, the electrochemical properties of these thin films were studied using cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) in

Location and characterisation of pollution sites by principal ...

African Journals Online (AJOL)

Location and characterisation of pollution sites by principal component analysis of trace contaminants in a slightly polluted seasonal river: a case study of the Arenales River (Salta, Argentina) ... Keywords: trace element contamination, water quality, principal component analysis, Arenales River, Salta, Argentina ...

Electrochemical treatment of tannery wastewater using DSA electrodes

International Nuclear Information System (INIS)

Costa, Carla Regina; Botta, Clarice M.R.; Espindola, Evaldo L.G.; Olivi, Paulo

2008-01-01

In this work we studied the electrochemical treatment of a tannery wastewater using dimensionally stable anodes (DSA) containing tin, iridium, ruthenium, and titanium. The electrodes were prepared by thermal decomposition of the polymeric precursors. The electrolyses were performed under galvanostatic conditions, at room temperature. Effects of the oxide composition, current density, and effluent conductivity were investigated, and the current efficiency was calculated as a function of the time for the performed electrolyses. Results showed that all the studied electrodes led to a decrease in the content of both total phenolic compounds and total organic carbon (TOC), as well as lower absorbance in the UV-vis region. Toxicity tests using Daphnia similis demonstrated that the electrochemical treatment reduced the wastewater toxicity. The use of DSA type electrodes in the electrochemical treatment of tannery wastewater proved to be useful since it can promote a decrease in total phenolic compounds, TOC, absorbance, and toxicity

Electrochemical treatment of tannery wastewater using DSA electrodes

Energy Technology Data Exchange (ETDEWEB)

Costa, Carla Regina [Departamento de Quimica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, CEP 14049-901 Ribeirao Preto, SP (Brazil); Botta, Clarice M.R.; Espindola, Evaldo L.G. [Nucleo de Estudos em Ecossistemas Aquaticos, Centro de Recursos Hidricos e Ecologia Aplicada, Escola de Engenharia de Sao Carlos, Universidade de Sao Paulo, CP 292, CEP 13560-970 Sao Carlos, SP (Brazil); Olivi, Paulo [Departamento de Quimica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, CEP 14049-901 Ribeirao Preto, SP (Brazil)], E-mail: olivip@ffclrp.usp.br

2008-05-01

In this work we studied the electrochemical treatment of a tannery wastewater using dimensionally stable anodes (DSA) containing tin, iridium, ruthenium, and titanium. The electrodes were prepared by thermal decomposition of the polymeric precursors. The electrolyses were performed under galvanostatic conditions, at room temperature. Effects of the oxide composition, current density, and effluent conductivity were investigated, and the current efficiency was calculated as a function of the time for the performed electrolyses. Results showed that all the studied electrodes led to a decrease in the content of both total phenolic compounds and total organic carbon (TOC), as well as lower absorbance in the UV-vis region. Toxicity tests using Daphnia similis demonstrated that the electrochemical treatment reduced the wastewater toxicity. The use of DSA type electrodes in the electrochemical treatment of tannery wastewater proved to be useful since it can promote a decrease in total phenolic compounds, TOC, absorbance, and toxicity.

Electrochemical photovoltaic cells and electrodes

Science.gov (United States)

Skotheim, Terje A.

1984-01-01

Improved electrochemical photovoltaic cells and electrodes for use therein, particularly electrodes employing amorphous silicon or polyacetylene coating are produced by a process which includes filling pinholes or porous openings in the coatings by electrochemical oxidation of selected monomers to deposit insulating polymer in the openings.

Electrochemical Hydrogen Evolution

DEFF Research Database (Denmark)

Laursen, A.B.; Varela Gasque, Ana Sofia; Dionigi, F.

2012-01-01

The electrochemical hydrogen evolution reaction (HER) is growing in significance as society begins to rely more on renewable energy sources such as wind and solar power. Thus, research on designing new, inexpensive, and abundant HER catalysts is important. Here, we describe how a simple experiment...... catalysts based on this. Suited for upper-level high school and first-year university students, this exercise involves using a basic two-cell electrochemical setup to test multiple electrode materials as catalysts at one applied potential, and then constructing a volcano curve with the resulting currents...

Electrochemical energy storage

CERN Document Server

Tarascon, Jean-Marie

2015-01-01

The electrochemical storage of energy has become essential in assisting the development of electrical transport and use of renewable energies. French researchers have played a key role in this domain but Asia is currently the market leader. Not wanting to see history repeat itself, France created the research network on electrochemical energy storage (RS2E) in 2011. This book discusses the launch of RS2E, its stakeholders, objectives, and integrated structure that assures a continuum between basic research, technological research and industries. Here, the authors will cover the technological

Synthesis, characterisation and electrochemical behaviour of Cu(II)

Indian Academy of Sciences (India)

Neutral tetradentate N2O2 type complexes of Cu(II), Ni(II), Co(II) and Zn(II) have been synthesised using the Schiff base formed by the condensation of acetylacetone and p-anisidine. Microanalysis, molar conductance, magnetic susceptibility, IR, UV-Vis, 1H NMR, CV and EPR studies have been carried out to determine the ...

Electrochemical non-enzymatic glucose sensors

International Nuclear Information System (INIS)

Park, Sejin; Boo, Hankil; Chung, Taek Dong

2006-01-01

The electrochemical determination of glucose concentration without using enzyme is one of the dreams that many researchers have been trying to make come true. As new materials have been reported and more knowledge on detailed mechanism of glucose oxidation has been unveiled, the non-enzymatic glucose sensor keeps coming closer to practical applications. Recent reports strongly imply that this progress will be accelerated in 'nanoera'. This article reviews the history of unraveling the mechanism of direct electrochemical oxidation of glucose and making attempts to develop successful electrochemical glucose sensors. The electrochemical oxidation of glucose molecules involves complex processes of adsorption, electron transfer, and subsequent chemical rearrangement, which are combined with the surface reactions on the metal surfaces. The information about the direct oxidation of glucose on solid-state surfaces as well as new electrode materials will lead us to possible breakthroughs in designing the enzymeless glucose sensing devices that realize innovative and powerful detection. An example of those is to introduce nanoporous platinum as an electrode, on which glucose is oxidized electrochemically with remarkable sensitivity and selectivity. Better model of such glucose sensors is sought by summarizing and revisiting the previous reports on the electrochemistry of glucose itself and new electrode materials

Microfluidic electrochemical device and process for chemical imaging and electrochemical analysis at the electrode-liquid interface in-situ

Science.gov (United States)

Yu, Xiao-Ying; Liu, Bingwen; Yang, Li; Zhu, Zihua; Marshall, Matthew J.

2016-03-01

A microfluidic electrochemical device and process are detailed that provide chemical imaging and electrochemical analysis under vacuum at the surface of the electrode-sample or electrode-liquid interface in-situ. The electrochemical device allows investigation of various surface layers including diffuse layers at selected depths populated with, e.g., adsorbed molecules in which chemical transformation in electrolyte solutions occurs.

3,5-Diamino-1,2,4-triazole@electrochemically reduced graphene oxide film modified electrode for the electrochemical determination of 4-nitrophenol

International Nuclear Information System (INIS)

Kumar, Deivasigamani Ranjith; Kesavan, Srinivasan; Baynosa, Marjorie Lara; Shim, Jae-Jin

2017-01-01

Highlights: •Triazole film was formed on electrochemically reduced graphene oxide. •pDAT@ERGO/GC was utilized for the electrochemical determination of 4-nitrophenol. •pDAT@ERGO/GC electrode offered wide concentration and nanomolar detection limit. •The fabricated electrode was employed in water sample analyses. -- Abstract: In this study, an eco-friendly benign method for the modification of electrochemically reduced graphene oxide (ERGO) on glassy carbon (GC) surface and electrochemical polymerized 3,5-diamino-1,2,4-triazole (DAT) film composite (pDAT@ERGO/GC) electrode was developed. The surface morphologies of the pDAT@ERGO/GC modified electrode were analyzed by field emission scanning electron microscopy (FESEM). FESEM images indicated that the ERGO supported pDAT has an almost homogeneous morphology structure with a size of 70 to 80 nm. It is due to the water oxidation reaction occurred while pDAT@ERGO/GC fabrication peak at +1.4 V leads to O 2 evolution and oxygen functional group functionalization on ERGO, which confirmed by X-ray photoelectron spectroscopy (XPS). In contrast, the bare GC modified with pDAT showed randomly arranged irregular bulky morphology structure compared to those of pDAT@ERGO/GC. Electrochemical reduction of graphene oxide was confirmed by Raman spectroscopy, XPS, and electrochemical impedance spectroscopy (EIS). The pDAT@ERGO/GC modified electrode was used for the electrochemical determination of 4-nitrophenol (4-NP). The 4-NP oxidation peak was observed at +0.25 V, and the differential pulse voltammetry demonstrated wide concentration range (5–1500 μM), high sensitivity (0.7113 μA μM −1 ), and low limit of detection (37 nM). Moreover, the pDAT@ERGO/GC electrode was applied to real water sample analysis by standard addition method, where in good recoveries (97.8% to 102.4%) were obtained.

Graphene derived carbon confined sulfur cathodes for lithium-sulfur batteries: Electrochemical impedance studies

International Nuclear Information System (INIS)

Ganesan, Aswathi; Varzi, Alberto; Passerini, Stefano; Shaijumon, Manikoth M.

2016-01-01

Highlights: • Graphene-derived carbon (GDC) with distinctive porosity characteristics are prepared. • Effect of micro-/mesoporosity of GDC for improved Li-S battery performance is studied. • Impedance studies reveal insights into Li-S redox reactions and capacity fading phenomena. - Abstract: Sulfur nanocomposites are prepared by using graphene derived carbon (GDC), with controlled porosity characteristics, as confining matrix and are studied as efficient cathodes for lithium-sulfur (Li-S) batteries. To understand the effect of micro-/mesoporosity in porous carbon for the effective encapsulation of sulfur and polysulfides towards improved Li-S battery performance, two different GDC samples with controlled porosity characteristics, one with predominantly micropores (GDC-1) and a surface area of 1970 m 2 g −1 and the other with a surface area of 3239 m 2 g −1 , having more or less equal contribution of micro- and mesopores (GDC-2), are used to synthesize nanocomposite sulfur electrodes following melt diffusion process. Electrochemical studies are carried out by using cyclic voltammetry, galvanostatic charge/discharge cycling and electrochemical impedance spectroscopy (EIS). EIS spectra collected at different depth of discharge (DOD) in the first cycle as well as upon cycling give valuable insights into the Li-S redox reactions and capacity fading phenomena in these electrodes. The impedance response of GDC-S electrodes suggests a detrimental effect of the mesopores, where insoluble reaction products can easily accumulate, resulting in the loss of active material leading to capacity fading of Li-S cells.

Investigation of electrochemical actuation by polyaniline nanofibers

Science.gov (United States)

Mehraeen, Shayan; Alkan Gürsel, Selmiye; Papila, Melih; Çakmak Cebeci, Fevzi

2017-09-01

Polyaniline nanofibers have shown promising electrical and electrochemical properties which make them prominent candidates in the development of smart systems employing sensors and actuators. Their electrochemical actuation potential is demonstrated in this study. A trilayer composite actuator based on polyaniline nanofibers was designed and fabricated. Cross-linked polyvinyl alcohol was sandwiched between two polyaniline nanofibrous electrodes as ion-containing electrolyte gel. First, electrochemical behavior of a single electrode was studied, showing reversible redox peak pairs in 1 M HCl using a cyclic voltammetry technique. High aspect ratio polyaniline nanofibers create a porous network which facilitates ion diffusion and thus accelerates redox reactions. Bending displacement of the prepared trilayer actuator was then tested and reported under an AC potential stimulation as low as 0.5 V in a variety of frequencies from 50 to 1000 mHz, both inside 1 M HCl solution and in air. Decay of performance of the composite actuator in air is investigated and it is reported that tip displacement in a solution was stable and repeatable for 1000 s in all selected frequencies.

Electrochemical and computational studies, in protic medium, of Morita-Baylis-Hillman adducts and correlation with leishmanicidal activity

International Nuclear Information System (INIS)

Paiva, Yen G. de; Pinho Júnior, Waldomiro; Souza, Antonio A. de; Costa, Cícero O.; Silva, Fábio P.L.; Lima-Junior, Cláudio G.; Vasconcellos, Mario L.A.A.; Goulart, Marília O.F.

2014-01-01

Highlights: • Twelve Morita-Baylis-Hillman adducts (MBHA) with significant leishmanicidal activity were studied by electrochemical and computational techniques, in protic media. • Ortho compounds for each series showed more negative reduction potentials than their positional isomers. • Less stable hydroxylamines were formed for ortho derivatives. • There is an inverse correlation between electrochemical parameters and bioactivity. - Abstract: Enzymatic bioreduction of nitro groups plays an important role on the activity of biologically active nitroaromatic compounds. Electrochemical methods are useful tools to simulate in vivo metabolic processes. This work presents electrochemical studies, in protic media (EtOH + phosphate buffer 4:6), using cyclic voltammetry (CV) of twelve Morita-Baylis-Hillman adducts (MBHA) with significant leishmanicidal activity. To facilitate the analysis, the molecules were grouped in four classes according to their side chains. Cyclic voltammograms display, in all cases, only one cathodic wave related to the formation of the correspondent hydroxylamines, which suffer further oxidation generating the nitroso derivatives in a sequential cycle. Ortho compounds exhibit more negative reduction potentials compared to the other isomers, in the same chemical class. This phenomenon could be related not only to structural effects but also to the presence of solvation spheres during the electroreduction process and/or stabilization of the resulting hydroxylamine. A proposal to explain the higher leishmanicidal activity of the ortho compounds compared with the meta and para compounds was suggested based on theoretical calculations (HF/6-31 + G */PCM, water, as a calculation level) that indicated lower thermodynamic stability for the ortho, in comparison to the corresponding meta and para hydroxylamines, fact that may suggest the easier transformation of the electrogenerated compounds into reactive electrophilic intermediates or final products

MECHANISTIC STUDY OF COLCHICINE’s ELECTROCHEMICAL OXIDATION

International Nuclear Information System (INIS)

Bodoki, Ede; Chira, Ruxandra; Zaharia, Valentin; Săndulescu, Robert

2015-01-01

Colchicine, as one of the most ancient drugs of human kind, is still in the focal point of the current research due to its multimodal mechanism of action. The elucidation of colchicine’s still unknown redox properties may play an important role in deciphering its beneficial and harmful implications over the human body. Therefore, a systematic mechanistic study of colchicine’s oxidation has been undertaken by electrochemistry coupled to mass spectrometry using two different types of electrolytic cells, in order to clarify the existing inconsistencies with respect to this topic. At around 1 V vs. Pd/H 2 , initiated by a one-electron transfer, the oxidation of colchicine sets off leading to a cation radical, whose further oxidation may evolve on several different pathways. The main product of the anodic electrochemical reaction, regardless of the carrier solution’s pH is represented by a 7-hydroxy derivative of colchicine. At more anodic potentials (above 1.4 V vs. Pd/H 2 ) compounds arising from epoxidation and/or multiple hydroxylation occur. No di- or tridemethylated quinone structures, as previously suggested in the literature for the electrolytic oxidation of colchicine, has been detected in the mass spectra.

Electrochemical impedance spectroscopic study of passive zirconium

Energy Technology Data Exchange (ETDEWEB)

Ai Jiahe; Chen Yingzi [Center for Electrochemical Science and Technology, Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Urquidi-Macdonald, Mirna [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802 (United States); Macdonald, Digby D. [Center for Electrochemical Science and Technology, Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)], E-mail: ddm2@psu.edu

2008-09-30

Spent, unreproccessed nuclear fuel is generally contained within the operational fuel sheathing fabricated from a zirconium alloy (Zircaloy 2, Zircaloy 4, or Zirlo) and is then stored in a swimming pool and/or dry storage facilities until permanent disposal in a licensed repository. During this period, which begins with irradiation of the fuel in the reactor during operation, the fuel sheathing is exposed to various, aggressive environments. The objective of the present study was to characterize the nature of the passive film that forms on pure zirconium in contact with an aqueous phase [0.1 M B(OH){sub 3} + 0.001 M LiOH, pH 6.94] at elevated temperatures (in this case, 250 deg. C), prior to storage, using electrochemical impedance spectroscopy (EIS) with the data being interpreted in terms of the point defect model (PDM). The results show that the corrosion resistance of zirconium in high temperature, de-aerated aqueous solutions is dominated by the outer layer. The extracted model parameter values can be used in deterministic models for predicting the accumulation of general corrosion damage to zirconium under a wide range of conditions that might exist in some repositories.

Thermodynamics of irreversible electrochemical phenomena

NARCIS (Netherlands)

Groot, S.R. de; Mazur, P.; Tolhoek, H.A.

1953-01-01

A discussion from first principles is given of the energy and entropy laws in electrochemical systems. It is found that it is possible to clarify such controversial concepts as the form of the second law and the role of the electrochemical potential in the systems concerned.

In Situ Investigation of Electrochemically Mediated Surface-Initiated Atom Transfer Radical Polymerization by Electrochemical Surface Plasmon Resonance.

Science.gov (United States)

Chen, Daqun; Hu, Weihua

2017-04-18

Electrochemically mediated atom transfer radical polymerization (eATRP) initiates/controls the controlled/living ATRP chain propagation process by electrochemically generating (regenerating) the activator (lower-oxidation-state metal complex) from deactivator (higher-oxidation-state metal complex). Despite successful demonstrations in both of the homogeneous polymerization and heterogeneous systems (namely, surface-initiated ATRP, SI-ATRP), the eATRP process itself has never been in situ investigated, and important information regarding this process remains unrevealed. In this work, we report the first investigation of the electrochemically mediated SI-ATRP (eSI-ATRP) by rationally combining the electrochemical technique with real-time surface plasmon resonance (SPR). In the experiment, the potential of a SPR gold chip modified by the self-assembled monolayer of the ATRP initiator was controlled to electrochemically reduce the deactivator to activator to initiate the SI-ATRP, and the whole process was simultaneously monitored by SPR with a high time resolution of 0.1 s. It is found that it is feasible to electrochemically trigger/control the SI-ATRP and the polymerization rate is correlated to the potential applied to the gold chip. This work reveals important kinetic information for eSI-ATRP and offers a powerful platform for in situ investigation of such complicated processes.

Image analysis for material characterisation

Science.gov (United States)

Livens, Stefan

In this thesis, a number of image analysis methods are presented as solutions to two applications concerning the characterisation of materials. Firstly, we deal with the characterisation of corrosion images, which is handled using a multiscale texture analysis method based on wavelets. We propose a feature transformation that deals with the problem of rotation invariance. Classification is performed with a Learning Vector Quantisation neural network and with combination of outputs. In an experiment, 86,2% of the images showing either pit formation or cracking, are correctly classified. Secondly, we develop an automatic system for the characterisation of silver halide microcrystals. These are flat crystals with a triangular or hexagonal base and a thickness in the 100 to 200 nm range. A light microscope is used to image them. A novel segmentation method is proposed, which allows to separate agglomerated crystals. For the measurement of shape, the ratio between the largest and the smallest radius yields the best results. The thickness measurement is based on the interference colours that appear for light reflected at the crystals. The mean colour of different thickness populations is determined, from which a calibration curve is derived. With this, the thickness of new populations can be determined accurately.

Preparation and Electrochemical Properties of Silver Doped Hollow Carbon Nanofibers

Directory of Open Access Journals (Sweden)

LI Fu

2016-11-01

Full Text Available Silver doped PAN-based hollow carbon nanofibers were prepared combining co-electrospinning with in situ reduction technique subsequently heat treatment to improve the electrochemical performances of carbon based supercapacitor electrodes. The morphology, structure and electrochemical performances of the resulted nanofiber were studied. The results show that the silver nanoparticles can be doped on the surface of hollow carbon nanofibers and the addition of silver favors the improvement of the electrochemical performances, exhibiting the enhanced reversibility of electrode reaction and the capacitance and the reduced charge transfer impedance.

AC impedance electrochemical modeling of lithium-ion positive electrodes

International Nuclear Information System (INIS)

Dees, D.; Gunen, E.; Abraham, D.; Jansen, A.; Prakash, J.

2004-01-01

Under Department of Energy's Advanced Technology Development Program,various analytical diagnostic studies are being carried out to examine the lithium-ion battery technology for hybrid electric vehicle applications, and a series of electrochemical studies are being conducted to examine the performance of these batteries. An electrochemical model was developed to associate changes that were observed in the post-test analytical diagnostic studies with the electrochemical performance loss during testing of lithium ion batteries. While both electrodes in the lithium-ion cell have been studied using a similar electrochemical model, the discussion here is limited to modeling of the positive electrode. The positive electrode under study has a composite structure made of a layered nickel oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ) active material, a carbon black and graphite additive for distributing current, and a PVDF binder all on an aluminum current collector. The electrolyte is 1.2M LiPF 6 dissolved in a mixture of EC and EMC and a Celgard micro-porous membrane is used as the separator. Planar test cells (positive/separator/negative) were constructed with a special fixture and two separator membranes that allowed the placement of a micro-reference electrode between the separator membranes (1). Electrochemical studies including AC impedance spectroscopy were then conducted on the individual electrodes to examine the performance and ageing effects in the cell. The model was developed by following the work of Professor Newman at Berkeley (2). The solid electrolyte interface (SEI) region, based on post-test analytical results, was assumed to be a film on the oxide and an oxide layer at the surface of the oxide. A double layer capacity was added in parallel with the Butler-Volmer kinetic expression. The pertinent reaction, thermodynamic, and transport equations were linearized for a small sinusoidal perturbation (3). The resulting system of differential equations was solved

An Electrochemical Impedance Spectroscopy Study on a Lithium Sulfur Pouch Cell

DEFF Research Database (Denmark)

Stroe, Daniel Loan; Knap, Vaclav; Swierczynski, Maciej Jozef

2016-01-01

The impedance behavior of a 3.4 Ah pouch Lithium-Sulfur cell was extensively characterized using the electrochemical impedance spectroscopy (EIS) technique. EIS measurements were performed at various temperatures and over the entire state-of-charge (SOC) interval without applying a superimposed DC...

Glucose biosensor based on disposable electrochemical paper-based transducers fully fabricated by screen-printing.

Science.gov (United States)

Lamas-Ardisana, P J; Martínez-Paredes, G; Añorga, L; Grande, H J

2018-06-30

This paper describes a new approach for the massive production of electrochemical paper-based analytical devices (ePADs). These devices are fully fabricated by screen-printing technology and consist of a lineal microfluidic channel delimited by hydrophobic walls (patterned with diluted ultraviolet screen-printing ink in chromatographic paper grade 4) and a three-electrode system (printed with carbon and/or Ag/AgCl conductive inks). The printing process was characterised and optimized for pattern each layer with only one squeeze sweep. These ePADs were used as transducers to develop a glucose biosensor. Ionic strength/pH buffering salts, electrochemical mediator (ferricyanide) and enzyme (glucose dehydrogenase FAD-dependent) were separately stored along the microfluidic channel in order to be successively dissolved and mixed after the sample dropping at the entrance. The analyses required only 10 µl and the biosensors showed good reproducibility (RSD = 6.2%, n = 10) and sensitivity (0.426 C/M cm 2 ), wide linear range (0.5-50 mM; r 2 = 0.999) and low limit of detection (0.33 mM). Furthermore, the new biosensor was applied for glucose determination in five commercial soft-drinks without any sample treatment before the analysis. These samples were also analysed with a commercial enzymatic-kit assay. The results indicated that both methods provide accurate results. Copyright © 2018 Elsevier B.V. All rights reserved.

Electrochemical sensing of etoposide using carbon quantum dot modified glassy carbon electrode.

Science.gov (United States)

Nguyen, Hoai Viet; Richtera, Lukas; Moulick, Amitava; Xhaxhiu, Kledi; Kudr, Jiri; Cernei, Natalia; Polanska, Hana; Heger, Zbynek; Masarik, Michal; Kopel, Pavel; Stiborova, Marie; Eckschlager, Tomas; Adam, Vojtech; Kizek, Rene

2016-04-25

In this study, enhancement of the electrochemical signals of etoposide (ETO) measured by differential pulse voltammetry (DPV) by modifying a glassy carbon electrode (GCE) with carbon quantum dots (CQDs) is demonstrated. In comparison with a bare GCE, the modified GCE exhibited a higher sensitivity towards electrochemical detection of ETO. The lowest limit of detection was observed to be 5 nM ETO. Furthermore, scanning electron microscopy (SEM), fluorescence microscopy (FM), and electrochemical impedance spectroscopy (EIS) were employed for the further study of the working electrode surface after the modification with CQDs. Finally, the GCE modified with CQDs under optimized conditions was used to analyse real samples of ETO in the prostate cancer cell line PC3. After different incubation times (1, 3, 6, 9, 12, 18 and 24 h), these samples were then prepared prior to electrochemical detection by the GCE modified with CQDs. High performance liquid chromatography with an electrochemical detection method was employed to verify the results from the GCE modified with CQDs.

Tunneling Mode of Scanning Electrochemical Microscopy: Probing Electrochemical Processes at Single Nanoparticles.

Science.gov (United States)

Sun, Tong; Wang, Dengchao; Mirkin, Michael V

2018-06-18

Electrochemical experiments at individual nanoparticles (NPs) can provide new insights into their structure-activity relationships. By using small nanoelectrodes as tips in a scanning electrochemical microscope (SECM), we recently imaged individual surface-bound 10-50 nm metal NPs. Herein, we introduce a new mode of SECM operation based on tunneling between the tip and a nanoparticle immobilized on the insulating surface. The obtained current vs. distance curves show the transition from the conventional feedback response to electron tunneling between the tip and the NP at separation distances of less than about 3 nm. In addition to high-resolution imaging of the NP topography, the tunneling mode enables measurement of the heterogeneous kinetics at a single NP without making an ohmic contact with it. The developed method should be useful for studying the effects of nanoparticle size and geometry on electrocatalytic activity in real-world applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical studies of CNT/Si–SnSb nanoparticles for lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Nithyadharseni, P. [Department of Physics, Bannari Amman Institute of Technology, Sathyamangalam 638402 (India); Department of Physics, Advanced Batteries Lab, National University of Singapore, 117542 (Singapore); Reddy, M.V., E-mail: phymvvr@nus.edu.sg [Department of Physics, Advanced Batteries Lab, National University of Singapore, 117542 (Singapore); Nalini, B., E-mail: lalin99@rediffmail.com [Department of Physics, Avinashilingam University for Women, Coimbatore 641043 (India); Ravindran, T.R. [Centre for Research in Nanotechnology, Karunya University, Coimbatore 641114 (India); Pillai, B.C.; Kalpana, M. [Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam 603102 (India); Chowdari, B.V.R. [Department of Physics, Advanced Batteries Lab, National University of Singapore, 117542 (Singapore)

2015-10-15

Highlights: • Si added SnSb and CNT exhibits very low particle size of below 30 nm • A strong PL quenching due to the addition of Si to SnSb. • Electrochemical studies show CNT added SnSb shows good capacity retention. - Abstract: Nano-structured SnSb, SnSb–CNT, Si–SnSb and Si–SnSb–CNT alloys were synthesized from metal chlorides of Sn, Sb and Si via reductive co-precipitation technique using NaBH{sub 4} as reducing agent. The as prepared compounds were characterized by various techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), Raman, Fourier transform infra-red (FTIR) and photoluminescence (PL) spectroscopy. The electrochemical performances of the compounds were characterized by galvanostatic cycling (GC) and cyclic voltammetry (CV). The Si–SnSb–CNT compound shows a high reversible capacity of 1200 mAh g{sup −1}. However, the rapid capacity fading was observed during cycling. In contrast, SnSb–CNT compound showed a high reversible capacity of 568 mAh g{sup −1} at 30th cycles with good cycling stability. The improved reversible capacity and cyclic performance of the SnSb–CNT compound could be attributed to the nanosacle dimension of SnSb particles and the structural advantage of CNTs.

Electrochemical polymer electrolyte membranes

CERN Document Server

Fang, Jianhua; Wilkinson, David P

2015-01-01

Electrochemical Polymer Electrolyte Membranes covers PEMs from fundamentals to applications, describing their structure, properties, characterization, synthesis, and use in electrochemical energy storage and solar energy conversion technologies. Featuring chapters authored by leading experts from academia and industry, this authoritative text: Discusses cutting-edge methodologies in PEM material selection and fabricationPoints out important challenges in developing PEMs and recommends mitigation strategies to improve PEM performanceAnalyzes the cur

Radiological Characterisation for Decommissioning of Nuclear Installations - Final Report of the Task Group on Radiological Characterisation and Decommissioning (RCD) of the Working Party on Decommissioning and Dismantling (WPDD) - Final Report, September 2013

International Nuclear Information System (INIS)

Andrieu, Caroline; Olivier Dehaye, Catherine; Tardy, Frederic; Boisserie, Thierry; Desnoyers, Yvon; Thierfeldt, Stefan; Martin, Nieves; Henrik Efraimsson; Haakansson, Lars; Larsson, Arne; Dunlop, Alister A.; Jarman, Sean; Orr, Peter; Abu-Eid, Boby

2013-01-01

consult the documents listed in the bibliography. The present report covers important aspects relating to radiological characterisation of nuclear installations with respect to decommissioning; it does not cover survey methods for clearance of materials and buildings or the release of sites. Chapter 2 describes the role and significance of radiological characterisation in decommissioning to provide an overview of this task, in particular with respect to the applied methods and its significance for a decommissioning project. Chapter 3 gives an overview on radiological characterisation during the various phases of a nuclear installation's life cycle and discusses how synergies with respect to efficient radiological characterisation can be exploited between various phases. Chapter 4 presents implementation issues for a typical radiological characterisation campaign. Practical information for implementing radiological characterisation in an efficient way is provided. Chapter 5 discusses overarching aspects that are relevant to all phases and that have more strategic importance. This chapter includes discussion of staff and organisational aspects, aspects related to performance of measurement and measurement strategies, use of integrated approaches and of issues/obstacles that have the potential to cause significant delays and increasing the costs. Chapter 6 provides a list of important lessons that have been learned from a multitude of decommissioning projects. Chapter 7 offers a short overview of areas suitable for further study, e.g. by OECD/NEA Task Groups. The reference list indicates sources that are directly referred to in the text. The bibliography section at the end of the document provides suggestions for further reading. Appendices provide information on the implementation of sampling strategies and requirements. The glossary explains some terms that may not be common in radiation protection literature or that have a special meaning in this report

The Binding Effect of Proteins on Medications and Its Impact on Electrochemical Sensing: Antipsychotic Clozapine as a Case Study

Directory of Open Access Journals (Sweden)

George E. Banis

2017-08-01

Full Text Available Clozapine (CLZ, a dibenzodiazepine, is demonstrated as the optimal antipsychotic for patients suffering from treatment-resistant schizophrenia. Like many other drugs, understanding the concentration of CLZ in a patient’s blood is critical for managing the patients’ symptoms, side effects, and overall treatment efficacy. To that end, various electrochemical techniques have been adapted due to their capabilities in concentration-dependent sensing. An open question associated with electrochemical CLZ monitoring is whether drug–protein complexes (i.e., CLZ bound to native blood proteins, such as serum albumin (SA or alpha-1 acid-glycoprotein (AAG contribute to electrochemical redox signals. Here, we investigate CLZ-sensing performance using fundamental electrochemical methods with respect to the impact of protein binding. Specifically, we test the activity of bound and free fractions of a mixture of CLZ and either bovine SA or human AAG. Results suggest that bound complexes do not significantly contribute to the electrochemical signal for mixtures of CLZ with AAG or SA. Moreover, the fraction of CLZ bound to protein is relatively constant at 31% (AAG and 73% (SA in isolation with varying concentrations of CLZ. Thus, electrochemical sensing can enable direct monitoring of only the unbound CLZ, previously only accessible via equilibrium dialysis. The methods utilized in this work offer potential as a blueprint in developing electrochemical sensors for application to other redox-active medications with high protein binding more generally. This demonstrates that electrochemical sensing can be a new tool in accessing information not easily available previously, useful toward optimizing treatment regimens.

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

International Nuclear Information System (INIS)

Liu Jingjun; Menchavez, Ruben L.; Watanabe, Hideo; Fuji, Masayoshi; Takahashi, Minoru

2008-01-01

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, H 2 SO 4 , HNO 3 , 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

Electrochemical investigation on an acrylated thiophene

Energy Technology Data Exchange (ETDEWEB)

Hogervorst, A.C.R. (TNO Plastics and Rubber Research Inst., Delft (Netherlands)); Kock, T.J.J.M. (TNO Plastics and Rubber Research Inst., Delft (Netherlands)); Ruiter, B. de (TNO Plastics and Rubber Research Inst., Delft (Netherlands)); Waal, A. van der (TNO Plastics and Rubber Research Inst., Delft (Netherlands))

1993-03-22

The electrochemical behaviour of electropolymerized 2-(3-thienyl)ethyl acrylate (PAcrT) has been investigated, and compared to the behaviour of electropolymerized thiophene and 3-n-decylthiophene (PDT). The effect of electron beam irradiation on the electrochemical properties of these three polymers has been studied. It has been found that for PAcrT the oxidation wave shifts to higher potentials upon electron beam irradiation. For PDT a similar but smaller change occurs. We suggest that the shift of the oxidation wave of PAcrT is caused by cross-links, formed between the acrylate substituents, which fixate the main chain parts in twisted states and reduce the conjugation length. (orig.)

Soil Radiological Characterisation Methodology

International Nuclear Information System (INIS)

Attiogbe, Julien; Aubonnet, Emilie; De Maquille, Laurence; De Moura, Patrick; Desnoyers, Yvon; Dubot, Didier; Feret, Bruno; Fichet, Pascal; Granier, Guy; Iooss, Bertrand; Nokhamzon, Jean-Guy; Ollivier Dehaye, Catherine; Pillette-Cousin, Lucien; Savary, Alain

2014-12-01

This report presents the general methodology and best practice approaches which combine proven existing techniques for sampling and characterisation to assess the contamination of soils prior to remediation. It is based on feedback of projects conducted by main French nuclear stakeholders involved in the field of remediation and dismantling (EDF, CEA, AREVA and IRSN). The application of this methodology will enable the project managers to obtain the elements necessary for the drawing up of files associated with remediation operations, as required by the regulatory authorities. It is applicable to each of the steps necessary for the piloting of remediation work-sites, depending on the objectives targeted (release into the public domain, re-use, etc.). The main part describes the applied statistical methodology with the exploratory analysis and variogram data, identification of singular points and their location. The results obtained permit assessment of a mapping to identify the contaminated surface and subsurface areas. It stakes the way for radiological site characterisation since the initial investigations from historical and functional analysis to check that the remediation objectives have been met. It follows an example application from the feedback of the remediation of a contaminated site on the Fontenay aux Roses facility. It is supplemented by a glossary of main terms used in the field from different publications or international standards. This technical report is a support of the ISO Standard ISO ISO/TC 85/SC 5 N 18557 'Sampling and characterisation principles for soils, buildings and infrastructures contaminated by radionuclides for remediation purposes'. (authors) [fr

Electrochemical study of nitrobenzene reduction using novel Pt nanoparticles/macroporous carbon hybrid nanocomposites

International Nuclear Information System (INIS)

Zhang Yufan; Zeng Lijun; Bo Xiangjie; Wang Huan; Guo Liping

2012-01-01

Graphical abstract: A one-step microwave-assisted route for rapidly synthesizing Pt nanoparticles ensemble on macroporous carbon hybrid nanocomposites (PNMPC) has been reported. As a novel electrode material, the excellent electrochemical behavior of nitrobenzene was investigated thoroughly at the PNMPC modified glassy carbon electrode. And moreover, the modified electrode was successfully applied to the determination of nitrobenzene in real samples. Highlights: ► One-step microwave-assisted heating synthesis Pt nanoparticles/macroporous carbon hybrid nanocomposites (PNMPC). ► Catalytic rate constant being 3.14 × 10 4 M −1 s −1 for NB in pH 7.0. ► Sensitive electrochemical detection of NB at the PNMPC/Nafion/GC electrode. ► The electrode showing excellent anti-interference ability and good stability for NB. - Abstract: Novel Pt nanoparticles (PN) ensemble on macroporous carbon (MPC) hybrid nanocomposites (PNMPC) were prepared through a rapidly and simple one-step microwave-assisted heating procedure. The obtained PNMPC was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and electrochemical methods. The electrochemical reduction of nitrobenzene (NB) was thoroughly investigated at the PNMPC modified glassy carbon (GC) electrode, and the catalytic rate constant was calculated to be 3.14 × 10 4 M −1 s −1 for NB. A sensitive NB sensor was developed based on the PNMPC/GC electrode, which showed a wide linear range (1–200 μM), low detection limit (50 nM), high sensitivity (6.93 μA μM −1 ), excellent anti-interference ability and good stability. And moreover, the electrode was successfully applied to the determination of NB in real samples.

Enzyme-Gelatin Electrochemical Biosensors: Scaling Down

Directory of Open Access Journals (Sweden)

Hendrik A. Heering

2012-03-01

Full Text Available In this article we investigate the possibility of scaling down enzyme-gelatin modified electrodes by spin coating the enzyme-gelatin layer. Special attention is given to the electrochemical behavior of the selected enzymes inside the gelatin matrix. A glassy carbon electrode was used as a substrate to immobilize, in the first instance, horse heart cytochrome c (HHC in a gelatin matrix. Both a drop dried and a spin coated layer was prepared. On scaling down, a transition from diffusion controlled reactions towards adsorption controlled reactions is observed. Compared to a drop dried electrode, a spin coated electrode showed a more stable electrochemical behavior. Next to HHC, we also incorporated catalase in a spin coated gelatin matrix immobilized on a glassy carbon electrode. By spincoating, highly uniform sub micrometer layers of biocompatible matrices can be constructed. A full electrochemical study and characterization of the modified surfaces has been carried out. It was clear that in the case of catalase, gluteraldehyde addition was needed to prevent leaking of the catalase from the gelatin matrix.

Structural and electrochemical study of the reaction of lithium with silicon nanowires

KAUST Repository

Chan, Candace K.; Ruffo, Riccardo; Hong, Seung Sae; Huggins, Robert A.; Cui, Yi

2009-01-01

The structural transformations of silicon nanowires when cycled against lithium were evaluated using electrochemical potential spectroscopy and galvanostatic cycling. During the charge, the nanowires alloy with lithium to form an amorphous Lix

Chip cleaning and regeneration for electrochemical sensor arrays

Energy Technology Data Exchange (ETDEWEB)

Bhalla, Vijayender [Biochemistry Department ' G.Moruzzi' , University of Bologna, Via Irnerio 48, 40126 Bologna (Italy); Carrara, Sandro, E-mail: sandro.carrara@epfl.c [Biochemistry Department ' G.Moruzzi' , University of Bologna, Via Irnerio 48, 40126 Bologna (Italy); Stagni, Claudio [Department DEIS, University of Bologna, viale Risorgimento 2, 40136 Bologna (Italy); Samori, Bruno [Biochemistry Department ' G.Moruzzi' , University of Bologna, Via Irnerio 48, 40126 Bologna (Italy)

2010-04-02

Sensing systems based on electrochemical detection have generated great interest because electronic readout may replace conventional optical readout in microarray. Moreover, they offer the possibility to avoid labelling for target molecules. A typical electrochemical array consists of many sensing sites. An ideal micro-fabricated sensor-chip should have the same measured values for all the equivalent sensing sites (or spots). To achieve high reliability in electrochemical measurements, high quality in functionalization of the electrodes surface is essential. Molecular probes are often immobilized by using alkanethiols onto gold electrodes. Applying effective cleaning methods on the chip is a fundamental requirement for the formation of densely-packed and stable self-assembly monolayers. However, the available well-known techniques for chip cleaning may not be so reliable. Furthermore, it could be necessary to recycle the chip for reuse. Also in this case, an effective recycling technique is required to re-obtain well cleaned sensing surfaces on the chip. This paper presents experimental results on the efficacy and efficiency of the available techniques for initial cleaning and further recycling of micro-fabricated chips. Piranha, plasma, reductive and oxidative cleaning methods were applied and the obtained results were critically compared. Some interesting results were attained by using commonly considered cleaning methodologies. This study outlines oxidative electrochemical cleaning and recycling as the more efficient cleaning procedure for electrochemical based sensor arrays.

Simplified fate modelling in respect to ecotoxicological and human toxicological characterisation of emissions of chemical compounds

DEFF Research Database (Denmark)

Birkved, Morten; Heijungs, Reinout

2011-01-01

The impact assessment of chemical compounds in Life Cycle Impact Assessment (LCIA) and Environmental Risk Assessment (ERA) requires a vast amount of data on the properties of the chemical compounds being assessed. The purpose of the present study is to explore statistical options for reduction...... of the data demand associated with characterisation of chemical emissions in LCIA and ERA.Based on a USEtox™ characterisation factor set consisting of 3,073 data records, multi-dimensional bilinear models for emission compartment specific fate characterisation of chemical emissions were derived by application...... the independent chemical input parameters from the minimum data set, needed for characterisation in USEtox™, according to general availability, importance and relevance for fate factor prediction.Each approach (63% and 75% of the minimum data set needed for characterisation in USEtox™) yielded 66 meta...

Methodology for characterisation of glass fibre composite architecture

DEFF Research Database (Denmark)

Hansen, Jens Zangenberg; Larsen, J.B.; Østergaard, R.C.

2012-01-01

of the fibres. The information is used for different analyses to investigate and characterise the fibre architecture. As an example, the methodology is applied to glass fibre reinforced composites with varying fibre contents. The different fibre volume fractions (FVFs) affect the number of contact points per......The present study outlines a methodology for microstructural characterisation of fibre reinforced composites containing circular fibres. Digital micrographs of polished cross-sections are used as input to a numerical image processing tool that determines spatial mapping and radii detection...... fibre, the communal fibre distance and the local FVF. The fibre diameter distribution and packing pattern remain somewhat similar for the considered materials. The methodology is a step towards a better understanding of the composite microstructure and can be used to evaluate the interconnection between...

Characterization of electrochemically and chemically generated technetium diphosphonate radiopharmaceuticals

International Nuclear Information System (INIS)

Martin, J.L. Jr.

1987-01-01

Tc-Methylene diphosphonate, (MDP), the skeletal imaging ligand is most use in radiopharmacies, is the first metal-ligand complex prepared electrochemically in this work. A similar systematic evaluation of electrochemically reduced Tc-dimethylaminomethylene diphosphonate (DMAD) is presented. DMAD as well as MDP have been characterized by anion exchange HPLC following NaBH4 reduction. The goal is twofold. First, the effect of varying the applied potential on the resultant chromatographic distribution of complexes is investigated. Secondly, the combination(s) of applied potential and preparation pH which preferentially directs the formation of technetium diphosphonate complexes previously shown to be superior skeletal imaging agents is determined. EXAFS, extended x-ray absorption fine structure spectroscopy, is applied to the analysis of dilute solutions (10mM) of electrochemically and chemically reduced Tc-MDP complexes. Further characterizations of electrochemically and chemically generated complexes are performed using in-vitro and in-vivo physiological techniques of biodistribution and blood clearance studies on Sprague Dawley rats and beagle dogs respectively. Finally, in-vitro and in-vivo dilution studies were performed using water, human and dog urine, to determine the influence of the physiological environment on clinically prepared and injected radiopharmaceuticals

A Study on Electrochemical Reduction of Rare Earth Oxides in Molten LiCl-Li2O Salt

International Nuclear Information System (INIS)

Lee, Min Woo; Jeong, Sang Mun; Lee, See Hoon; Sohn, Jung Min

2016-01-01

In this study, the electrochemical reduction of RE 2 O 3 (RE = Nd or Ce) has been conducted via co-reduction NiO to increase the reduction degree of the rare earth oxides in molten molten LiCl containing 1wt% Li 2 O. The electrochemical reduction behavior of the mixed RE 2 O 3 -NiO oxide has been investigated and the reduction path of RE 2 O 3 has been proposed. An electorchemical spent fuel processing technology, pyroprocessing, has been developed for recycling of spent fuel to be applied to a sodium-cooled fast reactor. The spent fuel is reduced in the oxide reduction process. It is well known that the rare earth oxides are hardly reduced due to their electrochemical and thermodynamic stability. The rare earth oxides unreduced in the reduction process can cause problems via reaction with UCl 3 in the electrorefiner. To tackle those problems, the electrochemical reduction of rare earth oxide has been conducted via co-reduction of NiO in LiCl molten salt containing 1 wt% Li 2 O. The reduction of the oxide mixture starts from the reduction of NiO to Ni, followed by that of RE 2 O 3 on the produced Ni to form intermetallic RENi 5 . The mixed oxide pellets were successfully reduced to the RENi5 alloy by constant electrolysis at 3.0 V at 650 .deg. C. The crucial aspect to these results is that the thermodynamically stable rare-earth oxide, Nd 2 O 3 was successfully converted to the metal in the presence of NiO.

Electrochemical Impedance Study of Zinc Yellow Polypropylene-Coated Aluminum Alloy

Directory of Open Access Journals (Sweden)

Zhi-hua Sun

2010-01-01

Full Text Available Performance of zinc yellow polypropylene-coated aluminum alloy 7B04 during accelerated degradation test is studied using electrochemical impedance spectroscopy (EIS. It has been found that the zinc yellow polypropylene paint has few flaw and acts as a pure capacitance before accelerated test. After 336-hour exposure to the test, the impedance spectroscopy shows two time constants, and water has reached to the aluminum alloy/paint interface and forms corrosive microcell. For the scratched samples, the reaction of metal corrosion and the hydrolysis of zinc yellow ion can occur simultaneously. The impedance spectroscopy indicates inductance after 1008-hour exposure to the test, but the inductance disappears after 1344-hour exposure and the passivation film has pitting corrosion.

Conducting polypyrrole films as a potential tool for electrochemical treatment of azo dyes in textile wastewaters

Energy Technology Data Exchange (ETDEWEB)

Haque, Md. Mominul [Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109 (Australia); Smith, Warren T. [Samadha Pacifica Pty Ltd, Woonona, NSW 2517 (Australia); Wong, Danny K.Y., E-mail: Danny.Wong@mq.edu.au [Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109 (Australia)

2015-02-11

Highlights: • Anion exchange property of polypyrrole films exploited in developing a treatment method for Acid Red 1. • An environmentally friendly treatment method for Acid Red 1 without generating any toxic by-products. • Acid Red 1 is anodically entrapped and cathodically liberated at polypyrrole films. • Analytical characteristics of Acid Red 1-entrapped polypyrrole films. - Abstract: In this paper, we demonstrate conducting polypyrrole films as a potential green technology for electrochemical treatment of azo dyes in wastewaters using Acid Red 1 as a model analyte. These films were synthesised by anodically polymerising pyrrole in the presence of Acid Red 1 as a supporting electrolyte. In this way, the anionic Acid Red 1 is electrostatically attracted to the cationic polypyrrole backbone formed to maintain electroneutrality, and is thus entrapped in the film. These Acid Red 1-entrapped polypyrrole films were characterised by electrochemical, microscopic and spectroscopic techniques. Based on a two-level factorial design, the solution pH, Acid Red 1 concentration and polymerisation duration were identified as significant parameters affecting the entrapment efficiency. The entrapment process will potentially aid in decolourising Acid Red 1-containing wastewaters. Similarly, in a cathodic process, electrons are supplied to neutralise the polypyrrole backbone, liberating Acid Red 1 into a solution. In this work, following an entrapment duration of 480 min in 2000 mg L{sup −1} Acid Red 1, we estimated 21% of the dye was liberated after a reduction period of 240 min. This allows the recovery of Acid Red 1 for recycling purposes. A distinctive advantage of this electrochemical Acid Red 1 treatment, compared to many other techniques, is that no known toxic by-products are generated in the treatment. Therefore, conducting polypyrrole films can potentially be applied as an environmentally friendly treatment method for textile effluents.

Electrochemical detection of Hg(II in water using self-assembled single walled carbon nanotube-poly(m-amino benzene sulfonic acid on gold electrode

Directory of Open Access Journals (Sweden)

Gauta Gold Matlou

2016-09-01

Full Text Available This work reports on the detection of mercury using single walled carbon nanotube-poly (m-amino benzene sulfonic acid (SWCNT-PABS modified gold electrode by self-assembled monolayers (SAMs technique. A thiol containing moiety (dimethyl amino ethane thiol (DMAET was used to facilitate the assembly of the SWCNT-PABS molecules onto the Au electrode surface. The successfully assembled monolayers were characterised using atomic force microscopy (AFM. Cyclic voltammetric and electrochemical impedance spectroscopic studies of the modified electrode (Au-DMAET-(SWCNT-PABS showed improved electron transfer over the bare Au electrode and the Au-DMAET in [Fe (CN6]3−/4− solution. The Au-DMAET-(SWCNT-PABS was used for the detection of Hg in water by square wave anodic stripping voltammetry (SWASV analysis at the following optimized conditions: deposition potential of −0.1 V, deposition time of 30 s, 0.1 M HCl electrolyte and pH 3. The sensor showed a good sensitivity and a limit of detection of 0.06 μM with a linear concentration range of 20 ppb to 250 ppb under the optimum conditions. The analytical applicability of the proposed method with the sensor electrode was tested with real water sample and the method was validated with inductively coupled plasma – optical emission spectroscopy. Keywords: Self-assembly, Gold electrode, Carbon nanotubes, Electrochemical detection, Mercury

Fabrication of a miniaturized cell using microsystem technologies for electrochemical applications

International Nuclear Information System (INIS)

Lakard, Boris; Jeannot, Jean-Claude; Spajer, Michel; Herlem, Guillaume; Labachelerie, Michel de; Blind, Pascal; Fahys, Bernard

2005-01-01

A new type of electrochemical cell has been developed for use in electrochemical, chemical and biological applications. Using a platinum microelectrode as working electrode, this cell incorporates a silver microelectrode as reference electrode. These microelectrodes, whose area is equal to 1 μm 2 , were fabricated using photolithography, sputtering, and focused ion beam (FIB) technologies since these micro-fabrication techniques allow us to develop miniaturized electrochemical cells useful either for nanoelectrochemistry or biosensors applications. In this study, we show it is possible to coat a surface by chemical or biological compounds by immersing the microelectrodes in a solution, then setting a difference of potential between the two microelectrodes of the cell. For example, we used this miniaturized cell to realize the electrochemical polymerization of aniline into polyaniline to show that this electrochemical cell is efficient to coat a surface with a thin film of polymer

Pullulan as a potent green inhibitor for corrosion mitigation of aluminum composite: Electrochemical and surface studies.

Science.gov (United States)

B P, Charitha; Rao, Padmalatha

2018-06-01

This work emphasizes the corrosion inhibition ability of pullulan, an environmentally benign fungal polysaccharide on acid corrosion of 6061Aluminum-15% (v) SiC (P) composite material (Al-CM). The electrochemical measurements such as potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) studies were carried out for the corrosion inhibition studies. Conditions were optimized to obtain maximum inhibition efficiency, by performing the experiment at varying concentrations of inhibitor, in the temperature range of 308K- 323K. Surface morphology studies were done to reaffirm the adsorption of inhibitor on the surface of composite material. Pullulan acted as mixed type of inhibitor with a maximum efficiency of 89% at 303K for the addition of 1.0 gL -1 of inhibitor. Evaluation of kinetic and thermodynamic parameters revealed that inhibitor underwent physical adsorption onto the surface of Al-CM and obeyed Freundlich adsorption isotherm. The surface characterization like SEM-EDX, AFM confirmed the adsorption of pullulan molecule. Pullulan can be considered as effective, eco friendly green inhibitor for the corrosion control of Al-CM. Copyright © 2018 Elsevier B.V. All rights reserved.

Electrochemical stability of ionic clathrate hydrates and their structural consideration

International Nuclear Information System (INIS)

Lee, Wonhee; Lim, Dongwook; Lee, Huen

2013-01-01

Although electrochemical stability is an essential factor in relation to the potential applications of ionic clathrate hydrates to solid electrolytes, most studies regarding the proton conductors have focused on their ionic conductivity and thermal stability. Solid electrolytes in various electrochemical devices have to endure the applied potentials; thus, we examined the linear sweep voltammograms of various tetraalkylammonium hydroxide hydrates in order to shed light on the trend of electrochemical stability depending on the hydrate structure. We revealed that the electrochemical stability of Me 4 NOH hydrates is mainly affected by both their ionic concentration and cage occupancy. In particular, the true clathrate structures of β-Me 4 NOH hydrates are more electrochemically stable than their α-forms that possess partially broken hydrogen bonds. We also observed that the binary THF–Pr 4 NOH and pure Bu 4 NOH clathrate hydrates exhibit greater electrochemical stability than those of pure Me 4 NOH hydrates having lower or similar ionic concentrations. These results are considered to arise from the fact that each of the Pr 4 N + and Bu 4 N + ions occupies an extended space comprising four cages, which leads to stabilization of the larger unit, whereas a Me 4 N + ion is completely included only in one cage

Characterisation of a uranium fire aerosol

International Nuclear Information System (INIS)

Leuscher, A.H.

1976-01-01

Uranium swarf, which can burn spontaneously in air, creates an aerosol which is chemically toxic and radiotoxic. The uptake of uranium oxide in the respiratory system is determined to a large extent by the characteristics of the aerosol. A study has been made of the methods by which aerosols can be characterised. The different measured and defined characteristics of particles are given. The normal and lognormal particle size distributions are discussed. Shape factors interrelating characteristics are explained. Experimental techniques for the characterisation of an aerosol are discussed, as well as the instruments that have been used in this study; namely the Andersen impactor, point-to-plane electrostatic precipitator and the Pollak counter. Uranium swarf was made to burn with a heated filament, and the resulting aerosol was measured. Optical and electron microscopy have been used for the determination of the projected area diameters, and the aerodynamic diameters have been determined with the impactor. The uranium fire aerosol can be represented by a bimodal, or monomodal, lognormal particle size distribution depending on the way in which the swarf burns. The determined activity median aerodynamic diameter of the two peaks were 0,49μm and 6,0μm respectively [af

Oxidative stabilization of polyacrylonitrile nanofibers and carbon nanofibers containing graphene oxide (GO: a spectroscopic and electrochemical study

Directory of Open Access Journals (Sweden)

İlknur Gergin

2017-08-01

Full Text Available In this study, a precursor for carbon nanofibers (CNF was fabricated via electrospinning and carbonized through a thermal process. Before carbonization, oxidative stabilization should be applied, and the oxidation mechanism also plays an important role during carbonization. Thus, the understanding of the oxidation mechanism is an essential part of the production of CNF. The oxidation process of polyacrylonitrile was studied and nanofiber webs containing graphene oxide (GO are obtained to improve the electrochemical properties of CNF. Structural and morphological characterizations of the webs are carried out by using attenuated total reflectance Fourier transform infrared spectroscopy and Raman spectroscopy, scanning electron microscopy, atomic force microscopy and transmission electron microscopy. Mechanical tests are performed with a dynamic mechanical analyzer, and thermal studies are conducted by using thermogravimetric analysis. Electrochemical impedance spectroscopy, and cyclic voltammetry are used to investigate capacitive behavior of the products. The proposed equivalent circuit model was consistent with charge-transfer processes taking place at interior pores filled with electrolyte.

Microsatellite markers of water buffalo, Bubalus bubalis - development, characterisation and linkage disequilibrium studies

Directory of Open Access Journals (Sweden)

Vaidhegi R

2009-10-01

Full Text Available Abstract Background Microsatellite markers are highly polymorphic and widely used in genome mapping and population genetic studies in livestock species. River buffalo, Bubalus bubalis is an economically important livestock species, though only a limited number of microsatellite markers have been reported thus far in this species. Results In the present study, using two different approaches 571 microsatellite markers have been characterized for water buffalo. Of the 571 microsatellite markers, 498 were polymorphic with average heterozygosity of 0.51 on a panel of 24 unrelated buffalo. Fisher exact test was used to detect LD between the marker pairs. Among the 137550 pairs of marker combination, 14.58% pairs showed significant LD (P Conclusion The high conservation of cattle microsatellite loci in water buffalo promises the usefulness of the cattle microsatellites markers on buffalo. The polymorphic markers characterised in this study will contribute to genetic linkage and radiation hybrid mapping of water buffalo and population genetic studies.

Modelling, fabrication and characterisation of THz fractal meta-materials

DEFF Research Database (Denmark)

Xiao, S.; Zhou, L.; Malureanu, Radu

2011-01-01

We present theoretical predictions, fabrication procedure and characterisation results of fractal metamaterials for the THz frequency range. The characterisation results match well the predicted response thus validating both the fabrication procedure as well as the simulation one. Such systems sh...

Electrochemical properties of ion implanted silicon

International Nuclear Information System (INIS)

Pham minh Tan.

1979-11-01

The electrochemical behaviour of ion implanted silicon in contact with hydrofluoric acid solution was investigated. It was shown that the implanted layer on silicon changes profoundly its electrochemical properties (photopotential, interface impedance, rest potential, corrosion, current-potential behaviour, anodic dissolution of silicon, redox reaction). These changes depend strongly on the implantation parameters such as ion dose, ion energy, thermal treatment and ion mass and are weakly dependent on the chemical nature of the implantation ion. The experimental results were evaluated and interpreted in terms of the semiconductor electrochemical concepts taking into account the interaction of energetic ions with the solid surface. The observed effects are thus attributed to the implantation induced damage of silicon lattice and can be used for profiling of the implanted layer and the electrochemical treatment of the silicon surface. (author)

Two-phase flow characterisation by nuclear magnetic resonance

International Nuclear Information System (INIS)

Leblond, J.; Javelot, S.; Lebrun, D.; Lebon, L.

1998-01-01

The results presented in this paper demonstrate the performance of the PFGSE-NMR to obtain a complete characterisation of two-phase flows. Different methods are proposed to characterise air-water flows in different regimes: stationary two-phase flows and flows in transient condition. Finally a modified PFGSE is proposed to analyse the turbulence of air-water bubbly flow. (author)

Electrochemical and micro-gravimetric corrosion studies on spent fuel provide relevant source term data for a repository performance assessment

International Nuclear Information System (INIS)

Wegen, Detlef H.; Bottomley, Paul D. W.; Glatz, Jean-Paul

2004-01-01

Various electrochemical methods (corrosion potential monitoring, AC impedance analysis and electrochemical noise monitoring) were used in the investigation of UO 2 samples: natural and doped with two different levels of 238 Pu (0.1 and 10 wt%) simulating the increasing α-intensities seen with time in the repository. The results were compared and were able to show the intense, but also the very local nature of the radiolysis and to demonstrate that corrosion rates were proportional to α-radiolysis and hence the 238 Pu content; the corrosion rates were in accordance with earlier work at ITU. By contrast it was seen that the redox potentials only gave information as to the bulk solution that did not reflect the true conditions at the electrode interface that were driving the corrosion processes of UO 2 dissolution in groundwaters. The study shows how electrochemical techniques can provide vital information on the corrosion mechanism at the UO 2 /solution interface

Evaluation of Electrochemical Treatment of Chloride Contaminated Mortar Containing GGBS

Directory of Open Access Journals (Sweden)

Ki Hong Lee

2017-01-01

Full Text Available The present study concerns the influence of cementitious binder on electrochemical treatment of steel embedded in salt contaminated mortar. As binder, ordinary Portland cement (OPC and ground granulated blast furnace slag (GGBS were used and the current density of 250–750 mA/m2 was applied for 4 weeks to complete electrochemical chloride extraction. To evaluate the effect of electrochemical treatment the chloride profile and corrosion behaviour covering chloride concentration, galvanic current density, linear polarization resistance, open circuit potential, and mass loss were measured. An increase in the applied direct current density resulted in a decrease in the chloride concentration at the vicinity of steel, accompanying the mitigated corrosion damage. The performance of electrochemical treatment was more remarkable in mortar containing GGBS presumably due to binding mechanism. However, corrosion damage was more detrimental in GGBS rather than OPC at a given potential, while GGBS had superior corrosion resistance to a corrosive environment and treatment conditions. Therefore, the electrochemical treatment should be conducted prudently to evaluate the corrosion state of embedded steel depending on binder type.

SUPPLEMENTARY INFORMATION A combined Electrochemical ...

Indian Academy of Sciences (India)

DELL

A combined Electrochemical and Theoretical study of pyridine-based Schiff bases as novel corrosion inhibitors for mild steel in hydrochloric acid medium. PARUL DOHAREa, M A QURAISHIb* and I B OBOTb. aDepartment of Chemistry, Indian Institute of Technology, Banaras Hindu University, Varanasi, Uttar. Pradesh 221 ...

Electrochemical studies of iron/carbonates system applied to the formation of thin layers of siderite on inert substrates

International Nuclear Information System (INIS)

Ithurbide, A.; Peulon, S.; Mandin, Ph.; Beaucaire, C.; Chausse, A.

2007-01-01

In order to understand the complex mechanisms of the reactions occurring, a methodology is developed. It is based on the use of compounds electrodeposited under the form of thin layers and which are used then as electrodes to study their interactions with the toxic species. It is in this framework that is studied the electrodeposition of siderite on inert substrates. At first, have been studied iron electrochemical systems in carbonated solutions. These studies have been carried out with classical electrochemical methods (cyclic voltametry, amperometry) coupled to in-situ measurements: quartz microbalance, pH. Different compounds have been obtained under the form of homogeneous and adherent thin layers. The analyses of these depositions, by different ex-situ characterizations (XRD, IR, SEM, EDS..) have revealed particularly the presence of siderite. Then, the influence of several experimental parameters (substrate, potential, medium composition, temperature) on the characteristics of siderite thin layers has been studied. From these experimental results, models have been proposed. (O.M.)

In situ electrochemical impedance spectroscopy of Zr-1%Nb under VVER primary circuit conditions

International Nuclear Information System (INIS)

Nagy, Gabor; Kerner, Zsolt; Pajkossy, Tamas

2002-01-01

Oxide layers were grown on tubular samples of Zr-1%Nb under conditions simulating those in VVER-type pressurised water reactors, viz. in near-neutral borate solutions in an autoclave at 290 deg. C. These samples were investigated using electrochemical impedance spectroscopy which was found to be suitable to follow in situ the corrosion process. A -CPE ox parallel R ox - element was used to characterise the oxide layer on Zr-1%Nb. Both the CPE ox coefficient, σ ox , and the parallel resistance, R ox , were found to be thickness dependent. The layer thickness, however, can only be calculated after a calibration procedure. The temperature dependence of the CPE ox element was also found to be anomalous while the temperature dependence of R ox indicates that the oxide layer has semiconductor properties. The relaxation time - defined as (R ox σ ox ) 1/α - was found to be quasi-independent of oxidation time and temperature; thus it is characteristic to the oxide layer on Zr-1%Nb

Robust high temperature oxygen sensor electrodes

DEFF Research Database (Denmark)

Lund, Anders

Platinum is the most widely used material in high temperature oxygen sensor electrodes. However, platinum is expensive and the platinum electrode may, under certain conditions, suffer from poisoning, which is detrimental for an oxygen sensor. The objective of this thesis is to evaluate electrode...... materials as candidates for robust oxygen sensor electrodes. The present work focuses on characterising the electrochemical properties of a few electrode materials to understand which oxygen electrode processes are limiting for the response time of the sensor electrode. Three types of porous platinum......-Dansensor. The electrochemical properties of the electrodes were characterised by electrochemical impedance spectroscopy (EIS), and the structures were characterised by x-ray diffraction and electron microscopy. At an oxygen partial pressures of 0.2 bar, the response time of the sensor electrode was determined by oxygen...

Current limitations and challenges in nanowaste detection, characterisation and monitoring

Energy Technology Data Exchange (ETDEWEB)

Part, Florian; Zecha, Gudrun [Department of Water-Atmosphere-Environment, University of Natural Resources and Life Sciences, Institute of Waste Management, Muthgasse 107, 1190 Vienna (Austria); Causon, Tim [Department of Chemistry, Division of Analytical Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna (Austria); Sinner, Eva-Kathrin [Department of Nanobiotechnology, Institute for Synthetic Bioarchitectures, University of Natural Resources and Life Sciences, Muthgasse 11/II, 1190 Vienna (Austria); Huber-Humer, Marion, E-mail: marion.huber-humer@boku.ac.at [Department of Water-Atmosphere-Environment, University of Natural Resources and Life Sciences, Institute of Waste Management, Muthgasse 107, 1190 Vienna (Austria)

2015-09-15

Highlights: • First review on detection of nanomaterials in complex waste samples. • Focus on nanoparticles in solid, liquid and gaseous waste samples. • Summary of current applicable methods for nanowaste detection and characterisation. • Limitations and challenges of characterisation of nanoparticles in waste. - Abstract: Engineered nanomaterials (ENMs) are already extensively used in diverse consumer products. Along the life cycle of a nano-enabled product, ENMs can be released and subsequently accumulate in the environment. Material flow models also indicate that a variety of ENMs may accumulate in waste streams. Therefore, a new type of waste, so-called nanowaste, is generated when end-of-life ENMs and nano-enabled products are disposed of. In terms of the precautionary principle, environmental monitoring of end-of-life ENMs is crucial to allow assessment of the potential impact of nanowaste on our ecosystem. Trace analysis and quantification of nanoparticulate species is very challenging because of the variety of ENM types that are used in products and low concentrations of nanowaste expected in complex environmental media. In the framework of this paper, challenges in nanowaste characterisation and appropriate analytical techniques which can be applied to nanowaste analysis are summarised. Recent case studies focussing on the characterisation of ENMs in waste streams are discussed. Most studies aim to investigate the fate of nanowaste during incineration, particularly considering aerosol measurements; whereas, detailed studies focusing on the potential release of nanowaste during waste recycling processes are currently not available. In terms of suitable analytical methods, separation techniques coupled to spectrometry-based methods are promising tools to detect nanowaste and determine particle size distribution in liquid waste samples. Standardised leaching protocols can be applied to generate soluble fractions stemming from solid wastes, while

Development of new corrosion inhibitor tested on mild steel supported by electrochemical study

Directory of Open Access Journals (Sweden)

Hussein Jwad Habeeb

2018-03-01

Full Text Available Mild steel is a metal which is commonly used in industrials and manufacturing of equipment for most industries round the world. It is cheaper cost compared with the other metals and its durable, hard and easy-to-wear physical properties make it a major choice in the manufacture of equipment parts. The main problem through the uses of mild steel in industry is its resistance against corrosion, especially in acidic solutions. This case led to raise the cost of maintenance of equipment that used mild steel and as a result increased costs for the company. Organic corrosive inhibitors that also act as green chemicals, 4-hydroxybenzylideneaminomethyl-5-ethyl-1,3,4-thiadiazol have been synthesized. This inhibitor is tested as corrosion inhibitor on a mild steel sample MS in 1 M hydrochloric acid solution (HCl using electrochemical measurements test includes PD (Potentiodynamic, EIS (Electrochemical impedance spectroscopy, OCP (Open circuit potential and EFM (electrochemical frequency modulation. The obtained results indicate that 4-hydroxybenzylideneaminomethyl-5-ethyl-1,3,4-thiadiazol acts as a good corrosion inhibitor for mild steel sample in HCl solution with efficiency above 90%. Changes in the impedance parameters postulated adsorption on the mild steel specimens' surfaces of, which it going to the formation of protective coating layer. It also shows that 4-hydroxybenzylideneaminomethyl-5-ethyl-1,3,4-thiadiazol corrosion inhibitors are effective in helping to reduce and slow down the corrosion process that occurs on mild steel surface in hydrochloric acid solution. Increase of corrosion inhibitor concentration provides a protective layer of mild steel. However, this protective layer becomes weak when the temperature of the solution increases. Keywords: Hydroxybenzylideneaminomethy, Potentiodynamic, Electrochemical frequency modulation, Impedance

Effect of electrochemical treatments on the surface chemistry of activated carbon

OpenAIRE

Berenguer Betrián, Raúl; Marco Lozar, Juan Pablo; Quijada Tomás, César; Cazorla Amorós, Diego; Morallón Núñez, Emilia

2008-01-01

The effect of the electrochemical treatment (galvanostatic electrolysis in a filter-press electrochemical cell) on the surface chemistry and porous structure of a granular activated carbon (GAC) has been analyzed by means of temperature-programmed desorption and N2 (at 77 K) and CO2 (at 273 K) adsorption isotherms. The anodic and cathodic treatments, the applied current (between 0.2 and 2.0 A) and the type of electrolyte (NaOH, H2SO4 and NaCl)have been studied as electrochemical variables. Bo...

Characterization of electrochemically modified polycrystalline platinum surfaces

Energy Technology Data Exchange (ETDEWEB)

Krebs, L.C.; Ishida, Takanobu.

1991-12-01

The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between {minus}0.24 and +1.25 V{sub SCE} while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-{rho}-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

Characterization of electrochemically modified polycrystalline platinum surfaces

Energy Technology Data Exchange (ETDEWEB)

Krebs, Leonard C. [State Univ. of New York (SUNY), Stony Brook, NY (United States); Ishida, Takanobu [State Univ. of New York (SUNY), Stony Brook, NY (United States)

1991-12-01

The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between -0.24 and +1.25 V_SCE while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-ρ-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

Electrochemical Control of Peptide Self-Organization on Atomically Flat Solid Surfaces: A Case Study with Graphite.

Science.gov (United States)

Seki, Takakazu; So, Christopher R; Page, Tamon R; Starkebaum, David; Hayamizu, Yuhei; Sarikaya, Mehmet

2018-02-06

The nanoscale self-organization of biomolecules, such as proteins and peptides, on solid surfaces under controlled conditions is an important issue in establishing functional bio/solid soft interfaces for bioassays, biosensors, and biofuel cells. Electrostatic interaction between proteins and surfaces is one of the most essential parameters in the adsorption and self-assembly of proteins on solid surfaces. Although the adsorption of proteins has been studied with respect to the electrochemical surface potential, the self-assembly of proteins or peptides forming well-organized nanostructures templated by lattice structure of the solid surfaces has not been studied in the relation to the surface potential. In this work, we utilize graphite-binding peptides (GrBPs) selected by the phage display method to investigate the relationship between the electrochemical potential of the highly ordered pyrolytic graphite (HOPG) and peptide self-organization forming long-range-ordered structures. Under modulated electrical bias, graphite-binding peptides form various ordered structures, such as well-ordered nanowires, dendritic structures, wavy wires, amorphous (disordered) structures, and islands. A systematic investigation of the correlation between peptide sequence and self-organizational characteristics reveals that the presence of the bias-sensitive amino acid modules in the peptide sequence has a significant effect on not only surface coverage but also on the morphological features of self-assembled structures. Our results show a new method to control peptide self-assembly by means of applied electrochemical bias as well as peptide design-rules for the construction of functional soft bio/solid interfaces that could be integrated in a wide range of practical implementations.

Electrochemical formation of uranium-zirconium alloy in LiCl-KCl melts

Energy Technology Data Exchange (ETDEWEB)

Murakami, Tsuyoshi, E-mail: m-tsuyo@criepi.denken.or.j [Central Research Institute of Electric Power Industry (CRIEPI), Komae-shi, Tokyo 201-8511 (Japan); Kato, Tetsuya; Kurata, Masaki [Central Research Institute of Electric Power Industry (CRIEPI), Komae-shi, Tokyo 201-8511 (Japan); Yamana, Hajimu [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

2009-11-15

Since zirconium is considered an electrochemically active species under practical conditions of the electrorefining process, it is crucial to understand the electrochemical behavior of zirconium in LiCl-KCl melts containing actinide ions. In this study, the electrochemical codeposition of uranium and zirconium on a solid cathode was performed. It was found that the delta-(U, Zr) phase, which is the only intermediate phase of the uranium-zirconium binary alloy system, was deposited on a tantalum substrate by potentiostatic electrolysis at -1.60 V (vs. Ag{sup +}/Ag) in LiCl-KCl melts containing 0.13 in mol% UCl{sub 3} and 0.23 in mol% ZrCl{sub 4} at 773 K. To our knowledge, this is the first report on the electrochemical formation of the delta-(U, Zr) phase. The relative partial molar properties of uranium in the delta-(U, Zr) phase were evaluated by measuring the open-circuit-potentials of the electrochemically prepared delta-phase electrode.

Electrochemical formation of uranium-zirconium alloy in LiCl-KCl melts

International Nuclear Information System (INIS)

Murakami, Tsuyoshi; Kato, Tetsuya; Kurata, Masaki; Yamana, Hajimu

2009-01-01

Since zirconium is considered an electrochemically active species under practical conditions of the electrorefining process, it is crucial to understand the electrochemical behavior of zirconium in LiCl-KCl melts containing actinide ions. In this study, the electrochemical codeposition of uranium and zirconium on a solid cathode was performed. It was found that the δ-(U, Zr) phase, which is the only intermediate phase of the uranium-zirconium binary alloy system, was deposited on a tantalum substrate by potentiostatic electrolysis at -1.60 V (vs. Ag + /Ag) in LiCl-KCl melts containing 0.13 in mol% UCl 3 and 0.23 in mol% ZrCl 4 at 773 K. To our knowledge, this is the first report on the electrochemical formation of the δ-(U, Zr) phase. The relative partial molar properties of uranium in the δ-(U, Zr) phase were evaluated by measuring the open-circuit-potentials of the electrochemically prepared δ-phase electrode.

Modified porous silicon for electrochemical sensor of para-nitrophenol

International Nuclear Information System (INIS)

Belhousse, S.; Belhaneche-Bensemra, N.; Lasmi, K.; Mezaache, I.; Sedrati, T.; Sam, S.; Tighilt, F.-Z.; Gabouze, N.

2014-01-01

Highlights: • Hybrid device based on Porous silicon (PSi) and polythiophene (PTh) was prepared. • Three types of PSi/PTh hybrid structures were elaborated: PSi/PTh, oxide/PSi/PTh and Amino-propyltrimethoxysilane (APTMES)/oxide/PSi/PTh. • PTh was grafted on PSi using electrochemical polymerization. • The electrodetection of para-nitrophenol (p-NPh) was performed by cyclic voltammetry. • Oxide/PSi/PTh and APTMES/oxide/PSi/PTh, based electrochemical sensor showed a good response toward p-NPh. - Abstract: Hybrid structures based on polythiophene modified porous silicon was used for the electrochemical detection of para-nitrophenol, which is a toxic derivative of parathion insecticide and it is considered as a major toxic pollutant. The porous silicon was prepared by anodic etching in hydrofluodic acid. Polythiophene films were then grown by electropolymerisation of thiophene monomer on three different surfaces: hydrogenated PSi, oxidized PSi and amine-terminated PSi. The morphology of the obtained structures were observed by scanning electron microscopy and characterized by spectroscopy (FTIR). Cyclic voltammetry was used to study the electrochemical response of proposed structures to para-nitrophenol. The results show a high sensitivity of the sensor and a linearity of the electrochemical response in a large concentration interval ranging from 1.5 × 10 −8 M to the 3 × 10 −4 M

Electrochemical Sensors Based on Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Md. Aminur Rahman

2009-03-01

Full Text Available This review focuses on recent contributions in the development of the electrochemical sensors based on carbon nanotubes (CNTs. CNTs have unique mechanical and electronic properties, combined with chemical stability, and behave electrically as a metal or semiconductor, depending on their structure. For sensing applications, CNTs have many advantages such as small size with larger surface area, excellent electron transfer promoting ability when used as electrodes modifier in electrochemical reactions, and easy protein immobilization with retention of its activity for potential biosensors. CNTs play an important role in the performance of electrochemical biosensors, immunosensors, and DNA biosensors. Various methods have been developed for the design of sensors using CNTs in recent years. Herein we summarize the applications of CNTs in the construction of electrochemical sensors and biosensors along with other nanomaterials and conducting polymers.

Electrochemical behaviour of rhenium-graphite electrode

International Nuclear Information System (INIS)

Varypaev, V.N.; Krasikov, V.L.

1980-01-01

Electrochemical behaviour of combination electrode from graphite with electrodeposited thin coating of electrolytic rhenium is studied. Solution of 0.5 m NaCl+0.04 m AlCl 3 served as an electrolite. Polarization galvanostatic curves of hydrogen evolution upon electrodes with conditional rhenium thickness of 3.5 and 0.35 μm, 35 and 3.5 nm are obtained. Possibility of preparation of rhenium-graphite cathode with extremely low rhenium consume, electro-chemical properties of which are simu-lar to purely rhenium cathode is shown. Such electrode is characterized with stable in time low cathode potential of hydrogen evolution in chloride electrolyte and during cathode polarization it is not affected by corrosion

Carbon Onions: Synthesis and Electrochemical Applications

Energy Technology Data Exchange (ETDEWEB)

McDonough, John K. [Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Science and Engineering; Gogotsi, Y. [Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Science and Engineering

2013-01-01

Onion-like carbon structures have been synthesized in many ways and large scale production is currently under study. The annealing method can satisfy the need for large scale production, though the ideal spherical shape is unachievable, and the temperature attainable in this method is not sufficient for treating the entire particle. The arc-discharge method provides an alternate pathway toward large scale synthesis. Due to its structure and electrochemical properties, carbon onions can be used as materials for electrochemical double layer capacitors (EDLC) and can be used to store energy across a much wider temperature range, which gives these materials advantages over conventional EDLCs. This and other aspects of carbon onions are discussed in this article.

Electrochemical Processes

DEFF Research Database (Denmark)

Bech-Nielsen, Gregers

1997-01-01

The notes describe in detail primary and secondary galvanic cells, fuel cells, electrochemical synthesis and electroplating processes, corrosion: measurments, inhibitors, cathodic and anodic protection, details of metal dissolution reactions, Pourbaix diagrams and purification of waste water from...

Electrochemical Studies of Benzophenone and Fluorenone Imines, Amines and Diphenyldiazomethane.

Science.gov (United States)

1982-01-01

exhaustive, controlled-potential electrolyses has also been described. 2 Cells. electrodes. and electrolysis procedures. All electrochemical experiments...scale electrolyses was monitored periodically by cyclic voltammetry. At the conclusion of the experiment, the electrolysis mixture was protonated in a...stainless steel * column packed with LiChrosorb RP8 or LiChrosorb RP18, 10-pm mean particle size. The eluting solvent was a mixture of methanol and water

Thermoluminescence characterisation of chemical vapour deposited diamond films

CERN Document Server

Mazzocchi, S; Bucciolini, M; Cuttone, G; Pini, S; Sabini, M G; Sciortino, S

2002-01-01

The thermoluminescence (TL) characteristics of a set of six chemical vapour deposited diamond films have been studied with regard to their use as off-line dosimeters in radiotherapy. The structural characterisation has been performed by means of Raman spectroscopy. Their TL responses have been tested with radiotherapy beams ( sup 6 sup 0 Co photons, photons and electrons from a linear accelerator (Linac), 26 MeV protons from a TANDEM accelerator) in the dose range 0.1-7 Gy. The dosimetric characterisation has yielded a very good reproducibility, a very low dependence of the TL response on the type of particle and independence of the radiation energy. The TL signal is not influenced by the dose rate and exhibits a very low thermal fading. Moreover, the sensitivity of the diamond samples compares favourably with that of standard TLD100 dosimeters.

Chemical characterisation of zircon-cadmium sulfoselenide ceramic pigments

International Nuclear Information System (INIS)

Gazulla Barreda, M. F.; Rodrigo Edo, M.; Blasco Roca, E.; Orduna Cordero, M.

2013-01-01

The present paper addresses the development of a methodology that allows the complete chemical characterisation of zircon cadmium sulfoselenide ceramic pigments including minor and major elements. To develop the methodology, five zircon-cadmium sulfoselenide pigments with different hues were selected, studying the different measurement process steps, from sample preparation to the optimisation of the measurement of the different components of the pigments by spectroscopic techniques (WD-XRF and elemental analysis by combustion and IR detection). The chemical characterisation method developed was validated with synthetic standards prepared from the mixture of certified reference materials and pure oxides because no certified referenced materials of this type of pigments were commercially available. The developed method can be used for a complete chemical characterization of zircon-cadmium sulfoselenide ceramic pigments with a very low uncertainty for all the elements analysed. (Author)

An Electrochemical Study of Two Self-Dopable Water-Soluble Aniline Derivatives: Electrochemical Deposition of Copolymers

Directory of Open Access Journals (Sweden)

Loredana Vacareanu

2012-01-01

Full Text Available An electrochemical study of two water-soluble aniline derivatives, N-(3-sulfopropyl aniline (AnPS and N-(3-sulfopropyl p-aminodiphenylamine (DAnPS, in aqueous acidic electrolytic solutions containing different kinds of doping anions (Cl −, SO4 2−, and ClO4 − was carried out. At sufficiently high anodic potential, the sulfonated aniline derivatives undergo oxidation processes yielding cation-radical and dimer intermediates, but no polymer deposition was observed on the working electrode surface. Experimental results showed that both aniline derivatives are electroactive compounds exhibiting redox behaviour in the range of potential of −0.2 V–1.6 V. Due to the self-doping effect induced by sulfonic groups, AnPS and DAnPS compounds have good electroactivity even in neat water solution. By adding a small amount of aniline into electrolytic system, thin layers of copolymers were deposited on the working electrode surface. The copolymer layers formed on the electrodes show a highly orientational and positional order, confirmed by AFM and XRD spectroscopic techniques. During the anodic oxidation processes some distinct colour changes were observed.

Electrochemical study of nanometric Si on carbon for lithium ion secondary batteries

Energy Technology Data Exchange (ETDEWEB)

Doh, Chil-Hoon; Lee, Jung-Hoon; Lee, Duck-Jun; Kim, Ju-Seok; Jin, Bong-Soo; Moon, Seong-In [Korea Electrotechnology Research Institute, Changwon 641-120 (Korea, Republic of); Hwang, Young-Ki [Kyungnam University, Masan 631-701 (Korea, Republic of); Park, Cheol-Wan, E-mail: chdoh@keri.re.k [Sodiff Advanced Materials Co. Ltd, Youngju 750-080 (Korea, Republic of)

2010-05-01

The electrochemical and thermochemical properties of a silicon-graphite composite anode for lithium ion batteries were evaluated. The electrochemical properties were varied by the condition of pretreatment. The electrochemical pretreatment of constant current (C/10) and constant potential for 24 h showed specific discharge and charge capacities of 941 and 781 mA h g{sup -1} to give a specific irreversible capacity of 161 mA h g{sup -1} and a coulombic efficiency of 83%. The initial cycle as the next cycle of pretreatment showed a specific charge capacity (Li desertion) of 698 mA h g{sup -1} and a coulombic efficiency of 95%. Coulombic efficiency at the fifth cycle was 97% to clear up almost all of the irreversible capacity. During the pretreatment cycle to the fourth cycle, the average specific charge capacity was 683 mA h g{sup -1} and the cumulative irreversible capacity was 264 mA h g{sup -1}. Exothermic heat values based on the specific capacity of the discharged (Li insertion) electrode of silicon-graphite composite for the temperature range of 50-300 {sup 0}C were 2.09 and 2.21 J mA{sup -1}h{sup -1} for 0 and 2 h as time of pretreatment in the case of just disassembled wet electrodes and 1.43 and 1.01 J mA{sup -1}h{sup -1} for 12 and 24 h as time of pretreatment in the case of dried electrodes, respectively.

Study on the Electrochemical Property of Microporous Cobalt Phosphite[Co_11(HPO_3)_8(OH)_6

International Nuclear Information System (INIS)

Lee, Dong Heon; Kang, Myunggoo; Jung, Hyun; Paek, Seung-Min

2016-01-01

Crystalline microporous cobalt phosphite, Co_11(HPO_3)_8(OH)_6, was prepared via facile hydrothermal route without the use of any templates or surfactants. The cobalt chloride hexahydrate (CoCl_2·6H_2O) and sodium hypophosphite monohydrate (NaH_2PO_2·H_2O) were employed as reactants, and sodium bicarbonate(NaHCO_3) was added to adjust the pH. The resultant Co_11(HPO_3)_8(OH)_6 shows dumbbell-like shape witha size of several micrometers. The obtained materials were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), and energy dispersive spectrometry (EDS). The Co_11(HPO_3)_8(OH)_6 is applied as electrochemical energy storage electrode material because of its unique microporous nature. Different aqueous electrolytes (LiOH, NaOH, and KOH) have been tested in order to study the effect of electrolyte cations on electrochemical behavior. To investigate the capacity and stability of Co_11(HPO_3)_8(OH)_6 electrode, cyclic voltammetry (CV), galvanostatic charge-discharge (GC), and cycle stability were performed in aqueous electrolytes with different cations at room temperature. We found that the electrochemical behavior of these materials is strongly dependent on the species of electrolyte cations (Li"+,Na"+, and K"+).

Study of electrochemical processes for separation of the actinides and lanthanides in molten fluoride media

International Nuclear Information System (INIS)

Zvejskova, R.; Chuchvalcova Bimova, K.; Lisy, F.; Soucek, P.

2005-01-01

The technology of the Molten Salt Reactors (MSR) is developed for two possible applications: For one thing as the Molten Salt Transmutation Reactor (MSTR) incinerating plutonium and minor actinides within reprocessing of spent fuel from PWR or FBR and for another thing as electricity generating MSR working under thorium uranium fuel cycle. Electrochemical separation processes are one of promising pyrochemical techniques that should enable the on-line reprocessing of circulating fuel salt in MSR (fuel cycle back-end). The former application represents the Czech P and T concept, in which framework the electrolytic separation can be applied both in the front-end and back-end of the MSTR fuel cycle. Within the front-end electro separation should follow the Fluoride Volatility Method (FVM), which should separate 95 % of uranium from the spent fuel in the form of volatile uranium hexafluoride. The residual uranium and fission products (FP) are supposed to be separated among others also by electrochemical methods. The presented work comprises the results reached within development of electrochemical separation of the actinides and fission products from each other by electrolytic deposition method on solid cathode in molten fluoride media, that represent he carrier salts of MSR technology. The knowledge of electrochemical properties (red-ox potentials, mainly of deposition potentials) is necessary for determination of separation possibilities of individual components by electrolysis. (authors)

Electrochemical studies of quinine in surfactant media using hanging mercury drop electrode: a cyclic voltammetric study.

Science.gov (United States)

Dar, Riyaz Ahmad; Brahman, Pradeep Kumar; Tiwari, Sweety; Pitre, Krishna Sadashiv

2012-10-01

The electrochemical behavior of quinine was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV) using surfactant. The reduction peak current of quinine increases remarkably in presence of 1% CTAB. Its electrochemical behavior is quasi-reversible in the Britton-Robinson buffers of pH 10.38 by exhibiting the well-defined single cathodic and anodic waves and the ratio of I(p)(a)/I(p)(c) approaching one at the scan rate of 500 mVs(-1). On the basis of CV, SWV and Coulometry, electrochemical reduction mechanism of quinine has been proposed which has shown that protonation occurs on the nitrogen of the quinoline moiety. Linearity was obtained when the peak currents (I(p)) were plotted against concentrations of quinine in the range of 30.0-230.0 ng mL(-1) with a detection limit of 0.132 ng mL(-1) in SWV and 90.0-630.0 ng mL(-1) with a detection limit of 0.238 ng mL(-1) in DPV. Fast and sensitive SWV has been applied for the quantitative analysis of quinine in bark of Cinchona sp. and in soft drinks and a good recovery was obtained. The accuracy and precision of the method are determined and validated statistically. No interferences from other food additives were observed. The relative standard deviation for intraday and interday assay was 0.89 and 0.73% (n=3) respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Experimental study of a solar-driven photo-electrochemical hybrid system for the decolorization of Acid Red 26

International Nuclear Information System (INIS)

Wang, Yiping; Chen, Miao; Huang, Qunwu; Cui, Yong; Jin, Yanchao; Cui, Lingyun; Wen, Chen

2017-01-01

Highlights: • A solar-driven photo-electrochemical system (S/EC/PS) was first constructed. • Solar spectrum was fully used for the dye decolorization, power supply and thermal. • The electricity needed for EC was offered by the hybrid system. • In comparison with S/PS, decolorization time of S/EC/PS shorten 50%. • PV panels has lower working temperature due to the water cooling. - Abstract: This study presents a new solar-driven hybrid system that integrated a photo-electrochemical reactor with a photovoltaics (PV) panel for azo dyes’ decolorization and electricity generation. Full spectrum of sunlight is utilized to optimize the color removal of Acid Red 26 (AR26) in this hybrid system. Persulfate (PS, S 2 O 4 2− ) was selected as the photochemical oxidant and Ti/IrO 2 -Ta 2 O 5 electrode was used as the anode. Experiments were made to evaluate the efficiency of decolorization and the performance of PV panels in different reaction conditions outdoors. The results showed that the synergistic effect of two processes was observed for the AR26 decolorization. Comparing with the solar/persulfate process or the electrochemical process alone, the complete color removal time by the hybrid system decreased up to 50% and 44.4% respectively. In this system, the water layer in the flow channel cooled PV panels by absorbing the far infrared spectrum of sunlight, and the increased temperature of wastewater from 7 °C to 16 °C enhanced the decolorization efficiency of AR26. Moreover, the generated electricity by PV panels could satisfy the energy demand of electrochemical oxidation.

Electrochemical studies on electroless ternary and quaternary Ni-P based alloys

International Nuclear Information System (INIS)

Balaraju, J.N.; Selvi, V. Ezhil; Grips, V.K. William; Rajam, K.S.

2006-01-01

The autocatalytic (electroless) deposition of Ni-P based alloys is a well-known commercial process that has found numerous applications because of their excellent anticorrosive, wear, magnetic, solderable properties, etc. It is a barrier coating, protecting the substrate by sealing it off from the corrosive environments, rather than by sacrificial action. The corrosion resistance varies with the phosphorus content of the deposit: relatively high for a high-phosphorus electroless nickel deposit but low for a low-phosphorus electroless nickel deposit. In the present investigation ternary Ni-W-P alloy films were prepared using alkaline citrate-based bath. Quaternary Ni-W-Cu-P films were deposited by the addition of 3 mM copper ions in ternary Ni-W-P bath. X-ray diffraction (XRD) studies indicated that all the deposits were nanocrystalline, i.e. 1.2, 2.1 and 6.0 nm, respectively, for binary, ternary and quaternary alloys. Corrosion resistance of the films was evaluated in 3.5% sodium chloride solution in non-deaerated and deaerated conditions by potentiodynamic polarization and electrochemical impedance (EIS) methods. Lower corrosion current density values were obtained for the coatings tested in deaerated condition. EIS studies showed that higher charge transfer resistance values were obtained for binary Ni-P coatings compared to ternary or quaternary coatings. For all the coatings a gradual increase in the anodic current density had been observed beyond 740 mV. In deaerated condition all the reported coatings exhibited a narrow passive region and all the values of E p , E tp and i pass were very close showing no major changes in the electrochemical behavior. In the non-deaerated conditions no passivation behavior had been observed for all these coatings

Pyrite Passivation by Triethylenetetramine: An Electrochemical Study

Directory of Open Access Journals (Sweden)

Yun Liu

2013-01-01

Full Text Available The potential of triethylenetetramine (TETA to inhibit the oxidation of pyrite in H2SO4 solution had been investigated by using the open-circuit potential (OCP, cyclic voltammetry (CV, potentiodynamic polarization, and electrochemical impedance (EIS, respectively. Experimental results indicate that TETA is an efficient coating agent in preventing the oxidation of pyrite and that the inhibition efficiency is more pronounced with the increase of TETA. The data from potentiodynamic polarization show that the inhibition efficiency (η% increases from 42.08% to 80.98% with the concentration of TETA increasing from 1% to 5%. These results are consistent with the measurement of EIS (43.09% to 82.55%. The information obtained from potentiodynamic polarization also displays that the TETA is a kind of mixed type inhibitor.

Structural characterisation and physical properties of Li MMnO 4 ( M=Cr, Ti) spinels

Science.gov (United States)

Arillo, M. A.; Cuello, G.; López, M. L.; Martín, P.; Pico, C.; Veiga, M. L.

2005-01-01

New spinel-type phases of general formula Li MMnO 4 ( M=Cr, Ti), derived from LiMn 2O 4 by substitution of Mn 3+ by Cr 3+ or Mn 4+ by Ti 4+, have been obtained and characterised. Neutron diffraction refinements confirm that both phases crystallise in the Fd3m space group, giving the cation distributions [Li] 8 a[CrMn] 16 dO 4 and [Li 0.66Ti 0.34] 8 a[Li 0.34MnTi 0.66] 16 dO 4. Electrical conductivity has been examined by various techniques showing that these materials behave as semiconductors. The electrochemical behaviour indicates different oxidation-reduction steps in both cases concomitant with the insertion/deinsertion of lithium in non-reversible processes. X-ray diffraction patterns show that the above process is topotactic in LiCrMnO 4. Magnetic data and neutron diffraction measurements show that no long-range magnetic ordering is present, suggesting a spin-glass transition for M=Cr at low temperature, while for M=Ti the presence of non-magnetic ions in the octahedral sublattice provokes an inherent magnetic frustration.

Electrochemical heterogeneity and corrosion resistance of a welded titanium-zirconium joint

International Nuclear Information System (INIS)

Polyakov, S.G.; Goncharov, A.B.; Onoprienko, L.M.; Smiyan, O.D.

1992-01-01

The electrochemical behavior and corrosion resistance of various welded joints of zirconium alloy N-2.5 with commercial titanium VT1 made by the argon-arc method are studied. Electrochemical heterogeneity is studied by measuring the distribution of potentials over the surface, galvanic currents, and recording of polarization curves for different zones of a welded joint in 5% sulfuric acid solution at 340 K. It is established that electrochemical heterogeneity of the zones of an N-2.5 + VT1 welded joint leads to acceleration of the cathodic process in a welded joint and the anodic process along the fusion line from the titanium direction where the greatest hydrogenation of the metal and corrosion damage is correspondingly observed

Sonochemical and sustainable synthesis of graphene-gold (G-Au) nanocomposites for enzymeless and selective electrochemical detection of nitric oxide.

Science.gov (United States)

Geetha Bai, Renu; Muthoosamy, Kasturi; Zhou, Meifang; Ashokkumar, Muthupandian; Huang, Nay Ming; Manickam, Sivakumar

2017-01-15

In this study, a sonochemical approach was utilised for the development of graphene-gold (G-Au) nanocomposite. Through the sonochemical method, simultaneous exfoliation of graphite and the reduction of gold chloride occurs to produce highly crystalline G-Au nanocomposite. The in situ growth of gold nanoparticles (AuNPs) took place on the surface of exfoliated few-layer graphene sheets. The G-Au nanocomposite was characterised by UV-vis, XRD, FTIR, TEM, XPS and Raman spectroscopy techniques. This G-Au nanocomposite was used to modify glassy carbon electrode (GCE) to fabricate an electrochemical sensor for the selective detection of nitric oxide (NO), a critical cancer biomarker. G-Au modified GCE exhibited an enhanced electrocatalytic response towards the oxidation of NO as compared to other control electrodes. The electrochemical detection of NO was investigated by linear sweep voltammetry analysis, utilising the G-Au modified GCE in a linear range of 10-5000μM which exhibited a limit of detection of 0.04μM (S/N=3). Furthermore, this enzyme-free G-Au/GCE exhibited an excellent selectivity towards NO in the presence of interferences. The synergistic effect of graphene and AuNPs, which facilitated exceptional electron-transfer processes between the electrolyte and the GCE thereby improving the sensing performance of the fabricated G-Au modified electrode with stable and reproducible responses. This G-Au nanocomposite introduces a new electrode material in the sensitive and selective detection of NO, a prominent biomarker of cancer. Copyright © 2016 Elsevier B.V. All rights reserved.

Study for electrochemical behavior of uranium oxide in a molten LiCl-Li2O system

International Nuclear Information System (INIS)

Park, Sung Bin; Park, Byung Heung; Seo, Chung Seok; Jung, Ki Jung; Park, Seong Won

2005-01-01

Interest in the electrolytic reduction of uranium oxide is increasing in the treatment of spent fuel oxides. With complicated and expensive procedures many reactive metals can be prepared in a pure metal form, the electrochemical reduction of a metal oxide has been recently proposed in metallurgy. The electrochemical reduction process is simple and rapid when compared to the conventional processes. The process can reduce the production costs and be applicable to a wide range of metal oxides. Chen et al. proposed the direct electrochemical reduction of titanium dioxide to titanium in a molten calcium chloride. Argonne National Laboratory (ANL) has reported the experimental results of an electrochemical reduction of the uranium oxide fuel in a bench-scale apparatus with a cyclic voltammetry, and has designed high-capacity reduction (HCR) cells and conducted three kg-scale UO 2 reduction runs. Gourishankar et al. classified the mechanisms of the electrolytic reduction of the metal oxides in a LiCl-Li 2 O molten salt system into two types; the simultaneous reduction and the direct electrochemical reduction. The uranium oxide in LiCl-Li 2 O molten salt was converted to uranium metal according to two mechanisms. Korea Atomic Energy Research Institute (KAERI) has developed the Advanced Spent Fuel Conditioning Process (ACP) to be an innovative technology in handling the PWR spent fuel. As part of ACP, the electrolytic reduction process (ER process) is the electrochemical reduction process of uranium oxide to uranium metal in molten salt. The ER process has advantages in a technical stability, an economic potential and a good proliferation resistance. KAERI has reported on the good experimental results of an electrochemical reduction of the uranium oxide in a 20 kg HM/batch lab-scale. In this work, cyclic voltammograms for a LiCl-3 wt% Li 2 O system and an U 3 O 8 -LiCl-3 wt% Li 2 O system with the integrated cathode assembly have been obtained. From the cyclic

Influence of graphene microstructures on electrochemical performance for supercapacitors

Directory of Open Access Journals (Sweden)

Youning Gong

2015-10-01

Full Text Available The influence of variant graphenes on electrochemical performance for supercapacitors was studied comparatively and systematically by using SEM, FTIR and Raman spectroscopy, cyclic voltammetry (CV, galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS. The results revealed that: 1 the nitrogen-doped graphene (N-G electrode exhibited the highest specific capacitance at the same voltage scan rate; 2 the specific capacitance of the N-G reached up to 243.5 F/g at 1 A/g, while regular graphite oxide (GO was 43.5 F/g and reduced graphene oxide (rGO was 67.9 F/g; 3 N-G exhibited the best supercapacitance performance and the superior electrochemical properties, which made it an ideal electrode material for supercapacitors.

Characterising encapsulated nuclear waste using cosmic-ray muon tomography

International Nuclear Information System (INIS)

Clarkson, A.; Hamilton, D.J.; Hoek, M.; Ireland, D.G.; Kaiser, R.; Keri, T.; Lumsden, S.; Mahon, D.F.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S.; Yang, G.; Johnstone, J.R.; Shearer, C.; Zimmerman, C.

2015-01-01

Tomographic imaging techniques using the Coulomb scattering of cosmic-ray muons have been shown previously to successfully identify and characterise low- and high-Z materials within an air matrix using a prototype scintillating-fibre tracker system. Those studies were performed as the first in a series to assess the feasibility of this technology and image reconstruction techniques in characterising the potential high-Z contents of legacy nuclear waste containers for the U.K. Nuclear Industry. The present work continues the feasibility study and presents the first images reconstructed from experimental data collected using this small-scale prototype system of low- and high-Z materials encapsulated within a concrete-filled stainless-steel container. Clear discrimination is observed between the thick steel casing, the concrete matrix and the sample materials assayed. These reconstructed objects are presented and discussed in detail alongside the implications for future industrial scenarios

Characterising encapsulated nuclear waste using cosmic-ray muon tomography

Science.gov (United States)

Clarkson, A.; Hamilton, D. J.; Hoek, M.; Ireland, D. G.; Johnstone, J. R.; Kaiser, R.; Keri, T.; Lumsden, S.; Mahon, D. F.; McKinnon, B.; Murray, M.; Nutbeam-Tuffs, S.; Shearer, C.; Yang, G.; Zimmerman, C.

2015-03-01

Tomographic imaging techniques using the Coulomb scattering of cosmic-ray muons have been shown previously to successfully identify and characterise low- and high-Z materials within an air matrix using a prototype scintillating-fibre tracker system. Those studies were performed as the first in a series to assess the feasibility of this technology and image reconstruction techniques in characterising the potential high-Z contents of legacy nuclear waste containers for the U.K. Nuclear Industry. The present work continues the feasibility study and presents the first images reconstructed from experimental data collected using this small-scale prototype system of low- and high-Z materials encapsulated within a concrete-filled stainless-steel container. Clear discrimination is observed between the thick steel casing, the concrete matrix and the sample materials assayed. These reconstructed objects are presented and discussed in detail alongside the implications for future industrial scenarios.

Electrochemical Evaluation of Corrosion Inhibiting Layers Formed in a Defect from Lithium-Leaching Organic Coatings

NARCIS (Netherlands)

Visser, P.; Meeusen, M.; Gonzalez Garcia, Y.; Terryn, H.A.; Mol, J.M.C.

2017-01-01

This work presents the electrochemical evaluation of protective layers generated in a coating defect from lithium-leaching organic coatings on AA2024-T3 aluminum alloys as a function of neutral salt spray exposure time. Electrochemical impedance spectroscopy was used to study the electrochemical

Electrochemical procedures in the treatment of the spent nuclear fuel

International Nuclear Information System (INIS)

Oliveira Forbicini, Christina Aparecida L.G. de.

1994-01-01

Taking into account the advantages of the electrochemical technique and operational features of contactors, type mixer-settler, a new electrolytic extraction equipment is presented. Preliminary studies on electrochemical reduction behavior were carried out with a single stage prototype to set the reliable parameters for the final multistage mixer-settler design (MIRELE). Titanium was the housing material (cathode) and platinum the anode. MIRELE was designed and manufactured at IPEN workshop. After operational tests, the equipment was installed in a glove-box and U/Pu electrochemical partitioning studies were accomplished. The influences of parameters, as hydrazine as scavenger agent in nitric acid medium, current density control in each transference unit and organic and aqueous flow rate on the process efficiency were verified. An uranium separation higher than 99,5% has been achieved. Based on these studies, a flowsheet for spent nuclear fuel treatment was performed, including: an U-Pu co-extraction and scrubbing step, a partial partitioning, followed by final partitioning both using electrochemical Pu reduction, and an uranium reextraction as last step. The product with Pu/U ratio 2,2 times higher than the initial one, with suitable composition for the MOX fuel re-fabrication, has been achieved, showing an important application of the equipment in the new concept of fuel recycling. Also, waste volume reduction, one of the important aspects of the process, has been obtained. Concluding the works, an electrochemical procedure for residual hydrazine decomposition, present in the plutonium product solution, was used to provide a safety operation during the concentration step. (author). 94 refs., 44 figs., 15 tabs

Menadione metabolism to thiodione in hepatoblastoma by scanning electrochemical microscopy

Science.gov (United States)

Mauzeroll, Janine; Bard, Allen J.; Owhadian, Omeed; Monks, Terrence J.

2004-01-01

The cytotoxicity of menadione on hepatocytes was studied by using the substrate generation/tip collection mode of scanning electrochemical microscopy by exposing the cells to menadione and detecting the menadione-S-glutathione conjugate (thiodione) that is formed during the cellular detoxication process and is exported from the cell by an ATP-dependent pump. This efflux was electrochemically detected and allowed scanning electrochemical microscopy monitoring and imaging of single cells and groups of highly confluent live cells. Based on a constant flux model, ≈6 × 106 molecules of thiodione per cell per second are exported from monolayer cultures of Hep G2 cells. PMID:15601769

Cuprous oxide thin films grown by hydrothermal electrochemical deposition technique

International Nuclear Information System (INIS)

Majumder, M.; Biswas, I.; Pujaru, S.; Chakraborty, A.K.

2015-01-01

Semiconducting cuprous oxide films were grown by a hydrothermal electro-deposition technique on metal (Cu) and glass (ITO) substrates between 60 °C and 100 °C. X-ray diffraction studies reveal the formation of cubic cuprous oxide films in different preferred orientations depending upon the deposition technique used. Film growth, uniformity, grain size, optical band gap and photoelectrochemical response were found to improve in the hydrothermal electrochemical deposition technique. - Highlights: • Cu 2 O thin films were grown on Cu and glass substrates. • Conventional and hydrothermal electrochemical deposition techniques were used. • Hydrothermal electrochemical growth showed improved morphology, thickness and optical band gap

In-situ SEM microchip setup for electrochemical experiments with water based solutions

DEFF Research Database (Denmark)

Jensen, Eric; Købler, C.; Jensen, Palle Skovhus

2013-01-01

Studying electrochemical (EC) processes with electron microscopes offers the possibility of achieving much higher resolution imaging of nanoscale processes in real time than with optical microscopes. We have developed a vacuum sealed liquid sample electrochemical cell with electron transparent wi...

NICKEL HYDROXIDE FILMS IN CONTACT WITH AN ELECTROACTIVE SOLUTION. A STUDY EMPLOYING ELECTROCHEMICAL IMPEDANCE MEASUREMENTS

OpenAIRE

RICARDO TUCCERI

2018-01-01

The deactivation of nickel hydroxide films after prolonged storage times without use was studied. This study was carried out in the context of the Rotating Disc Electrode Voltammetry (RDEV) and Electrochemical Impedance Spectroscopy (EIS) when the nickel hydroxide film contacts an electroactive solution and a redox reaction occurs at the Au-Ni(OH)2|electrolyte interface. Deferasirox (4-(3,5-bis(2- hydroxyphenyl)-1,2,4-triazol-1-yl) benzoic acid) was employed as redox species in solution. Limi...

Hyphenated analytical techniques for materials characterisation

International Nuclear Information System (INIS)

Armstrong, Gordon; Kailas, Lekshmi

2017-01-01

This topical review will provide a survey of the current state of the art in ‘hyphenated’ techniques for characterisation of bulk materials, surface, and interfaces, whereby two or more analytical methods investigating different properties are applied simultaneously to the same sample to better characterise the sample than can be achieved by conducting separate analyses in series using different instruments. It is intended for final year undergraduates and recent graduates, who may have some background knowledge of standard analytical techniques, but are not familiar with ‘hyphenated’ techniques or hybrid instrumentation. The review will begin by defining ‘complementary’, ‘hybrid’ and ‘hyphenated’ techniques, as there is not a broad consensus among analytical scientists as to what each term means. The motivating factors driving increased development of hyphenated analytical methods will also be discussed. This introduction will conclude with a brief discussion of gas chromatography-mass spectroscopy and energy dispersive x-ray analysis in electron microscopy as two examples, in the context that combining complementary techniques for chemical analysis were among the earliest examples of hyphenated characterisation methods. The emphasis of the main review will be on techniques which are sufficiently well-established that the instrumentation is commercially available, to examine physical properties including physical, mechanical, electrical and thermal, in addition to variations in composition, rather than methods solely to identify and quantify chemical species. Therefore, the proposed topical review will address three broad categories of techniques that the reader may expect to encounter in a well-equipped materials characterisation laboratory: microscopy based techniques, scanning probe-based techniques, and thermal analysis based techniques. Examples drawn from recent literature, and a concluding case study, will be used to explain the

Hyphenated analytical techniques for materials characterisation

Science.gov (United States)

Armstrong, Gordon; Kailas, Lekshmi

2017-09-01

This topical review will provide a survey of the current state of the art in ‘hyphenated’ techniques for characterisation of bulk materials, surface, and interfaces, whereby two or more analytical methods investigating different properties are applied simultaneously to the same sample to better characterise the sample than can be achieved by conducting separate analyses in series using different instruments. It is intended for final year undergraduates and recent graduates, who may have some background knowledge of standard analytical techniques, but are not familiar with ‘hyphenated’ techniques or hybrid instrumentation. The review will begin by defining ‘complementary’, ‘hybrid’ and ‘hyphenated’ techniques, as there is not a broad consensus among analytical scientists as to what each term means. The motivating factors driving increased development of hyphenated analytical methods will also be discussed. This introduction will conclude with a brief discussion of gas chromatography-mass spectroscopy and energy dispersive x-ray analysis in electron microscopy as two examples, in the context that combining complementary techniques for chemical analysis were among the earliest examples of hyphenated characterisation methods. The emphasis of the main review will be on techniques which are sufficiently well-established that the instrumentation is commercially available, to examine physical properties including physical, mechanical, electrical and thermal, in addition to variations in composition, rather than methods solely to identify and quantify chemical species. Therefore, the proposed topical review will address three broad categories of techniques that the reader may expect to encounter in a well-equipped materials characterisation laboratory: microscopy based techniques, scanning probe-based techniques, and thermal analysis based techniques. Examples drawn from recent literature, and a concluding case study, will be used to explain the

Preparation and property study of MnO2/CNPs as electrode materials of electrochemical supercapacitors

Directory of Open Access Journals (Sweden)

JIANG Chao

2016-12-01

Full Text Available MnO2 nanorods deposited on carbon nanospheres (MnO2/CNPs as electrode materials of electrochemical supercapacitors have been synthesized via a hydrothermal synthesis.The micro morphologies and phases of the as-prepared MnO2/CNPs were characterized by field emission scanning electro microscopy(FESEM and X-ray diffraction(XRD.The electrochemical properties of nanomaterials were tested by cyclic voltammetry and galvanostatic charge-discharge.At a current density of 0.1 A/g using 1 mol/L Na2SO4 as electrolyte,the as-prepared MnO2/CNPs exhibit excellent specific capacitance of 305.6 F/g,far larger than carbon nanospheres (49.3 F/g.At a current density of 5 A/g,the specific capacitance of MnO2/CNPs is 235 F/g,which is 76.9% of the specific capacitance under 1 A/g current density.These results demonstrated that MnO2/CNPs may show potential application for electrode materials in electrochemical supercapacitors.

Electrochemical stability and postmortem studies of Pt/SiC catalysts for polymer electrolyte membrane fuel cells

DEFF Research Database (Denmark)

Stamatin, Serban Nicolae; Spéder, József; Dhiman, Rajnish

2015-01-01

In the presented work, the electrochemical stability of platinized silicon carbide is studied. Postmortem transmission electron microscopy and X-ray photoelectron spectroscopy were used to document the change in the morphology and structure upon potential cycling of Pt/SiC catalysts. Two differen......, silicon carbide undergoes at least mild oxidation if not even silicon leaching....

Mechanical characterisation of agarose-based chromatography resins for biopharmaceutical manufacture.

Science.gov (United States)

Nweke, Mauryn C; McCartney, R Graham; Bracewell, Daniel G

2017-12-29

Mechanical characterisation of agarose-based resins is an important factor in ensuring robust chromatographic performance in the manufacture of biopharmaceuticals. Pressure-flow profiles are most commonly used to characterise these properties. There are a number of drawbacks with this method, including the potential need for several re-packs to achieve the desired packing quality, the impact of wall effects on experimental set up and the quantities of chromatography media and buffers required. To address these issues, we have developed a dynamic mechanical analysis (DMA) technique that characterises the mechanical properties of resins based on the viscoelasticity of a 1ml sample of slurry. This technique was conducted on seven resins with varying degrees of mechanical robustness and the results were compared to pressure-flow test results on the same resins. Results show a strong correlation between the two techniques. The most mechanically robust resin (Capto Q) had a critical velocity 3.3 times higher than the weakest (Sepharose CL-4B), whilst the DMA technique showed Capto Q to have a slurry deformation rate 8.3 times lower than Sepharose CL-4B. To ascertain whether polymer structure is indicative of mechanical strength, scanning electron microscopy images were also used to study the structural properties of each resin. Results indicate that DMA can be used as a small volume, complementary technique for the mechanical characterisation of chromatography media. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Synthesis and electrochemical performance of hierarchical Sb2S3 nanorod-bundles for lithium-ion batteries

Directory of Open Access Journals (Sweden)

XIAOZHONG ZHOU

2014-05-01

Full Text Available Uniform hierarchical Sb2S3 nanorod-bundles were synthesised successfully by L-cysteine hydrochloride-assisted solvothermal treatment, and were then characterised by X-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy, respectively. The electrochemical performance of the synthesised Sb2S3 nanorod-bundles was investigated by cyclic voltammetry and galvanostatic charge−discharge technique, respectively. This material was found to exhibit a high initial charge specific capacity of 803 mA h g-1 at a rate of 100 mA g-1, a good cyclability of 614 mA h g-1 at a rate of 100 mA g-1 after 30 cycles, and a good rate capability of 400 mA h g-1 at a rate of 500 mA g-1 when evaluated as an electrode candidate material for lithium-ion batteries.

Electrochemical performance of 3D porous Ni-Co oxide with electrochemically exfoliated graphene for asymmetric supercapacitor applications

International Nuclear Information System (INIS)

Kim, Dae Kyom; Hwang, Minsik; Ko, Dongjin; Kang, Jeongmin; Seong, Kwang-dong; Piao, Yuanzhe

2017-01-01

Graphical abstract: The paper reported the Ni-Co oxide/electrochemically exfoliated graphene nanocomposites with 3D porous nano-architectures (NC-EEG) using a simple low temperature solution method combined with a thermal annealing treatment. 3D porous architectures provide large surface areas and shorten electron diffusion pathways for high performance asymmetric supercapacitors. Display Omitted -- Highlights: •A simple low temperature solution method was used for preparing NC-EEG. •Graphene sheets were obtained by electrochemically exfoliation process. •A high capacity of NC-EEG in a three-electrode system, as high as 649 C g −1 , was recorded. •Asymmetric supercapacitor based on NC-EEG exhibited excellent energy density and power density. -- Abstract: Ni-Co oxide, one of the binary metal oxides, has many advantages for use in high-performance supercapacitor electrode materials due to its relatively high electronic conductivity and improved electrochemical performance. In this work, Ni-Co oxide/electrochemically exfoliated graphene nanocomposites (NC-EEG) are successfully synthesized using a simple low temperature solution method combined with a thermal annealing treatment. Graphene sheets are directly obtained by an electrochemical exfoliation process with graphite foil, which is very simple, environmentally friendly, and has a relatively short reaction time. This electrochemically exfoliated graphene (EEG) can improve the electrical conductivity of the Ni-Co oxide nanostructures. The as-prepared NC-EEG nanocomposites have 3D porous architectures that can provide large surface areas and shorten electron diffusion pathways. Electrochemical properties were performed by cyclic voltammetry and galvanostatic charge/discharge in a 6 M KOH electrolyte. The NC-EEG nanocomposites exhibited a high capacity value of 649 C g −1 at a current density of 1.0 A g −1 . The asymmetric supercapacitors, manufactured on the basis of NC-EEG nanocomposites as a positive

Sintering effect on material properties of electrochemical reactors used for removal of nitrogen oxides and soot particles emitted from diesel engines

DEFF Research Database (Denmark)

He, Zeming; Andersen, Kjeld Bøhm; Keel, Li

2010-01-01

In the present work, 12-layered electrochemical reactors (comprising five cells) with a novel configuration including supporting layer lanthanum strontium manganate (LSM)-yttria stabilised zirconia (YSZ), electrode layer LSM-gadolinia-doped cerium oxide (CGO) and electrolyte layer CGO were...... fabricated via the processes of slurry preparation, tape casting and lamination and sintering. The parameters of porosity, pore size, pore size distribution, shrinkage, flow rate of the sintered reactors and the electrical conductivities of the supporting layer and the electrode in the sintered reactors were...... characterised. The effect of sintering temperature on microstructures and properties of the sintered samples was discussed, and 1,250 °C was determined as the appropriate sintering temperature for reactor production based on the performance requirements for applications. Using the present ceramic processing...

Characterisation of metal combustion with DUST code

Energy Technology Data Exchange (ETDEWEB)

García-Cascales, José R., E-mail: jr.garcia@upct.es [DITF, ETSII, Universidad Politécnica de Cartagena, Dr Fleming s/n, 30202 Murcia (Spain); Velasco, F.J.S. [Centro Universitario de la Defensa de San Javier, MDE-UPCT, C/Coronel Lopez Peña s/n, 30730 Murcia (Spain); Otón-Martínez, Ramón A.; Espín-Tolosa, S. [DITF, ETSII, Universidad Politécnica de Cartagena, Dr Fleming s/n, 30202 Murcia (Spain); Bentaib, Ahmed; Meynet, Nicolas; Bleyer, Alexandre [Institut de Radioprotection et Sûreté Nucléaire, BP 17, 92260 Fontenay-aux-Roses (France)

2015-10-15

Highlights: • This paper is part of the work carried out by researchers of the Technical University of Cartagena, Spain and the Institute of Radioprotection and Nuclear Security of France. • We have developed a code for the study of mobilisation and combustion that we have called DUST by using CAST3M, a multipurpose software for studying many different problems of Mechanical Engineering. • In this paper, we present the model implemented in the code to characterise metal combustion which describes the combustion model, the kinetic reaction rates adopted and includes a first comparison between experimental data and calculated ones. • The results are quite promising although suggest that improvement must be made on the kinetic of the reaction taking place. - Abstract: The code DUST is a CFD code developed by the Technical University of Cartagena, Spain and the Institute of Radioprotection and Nuclear Security, France (IRSN) with the objective to assess the dust explosion hazard in the vacuum vessel of ITER. Thus, DUST code permits the analysis of dust spatial distribution, remobilisation and entrainment, explosion, and combustion. Some assumptions such as particle incompressibility and negligible effect of pressure on the solid phase make the model quite appealing from the mathematical point of view, as the systems of equations that characterise the behaviour of the solid and gaseous phases are decoupled. The objective of this work is to present the model implemented in the code to characterise metal combustion. In order to evaluate its ability analysing reactive mixtures of multicomponent gases and multicomponent solids, two combustion problems are studied, namely H{sub 2}/N{sub 2}/O{sub 2}/C and H{sub 2}/N{sub 2}/O{sub 2}/W mixtures. The system of equations considered and finite volume approach are briefly presented. The closure relationships used are commented and special attention is paid to the reaction rate correlations used in the model. The numerical

Nickel-cobalt hydroxide nanosheets: Synthesis, morphology and electrochemical properties.

Science.gov (United States)

Schneiderová, Barbora; Demel, Jan; Zhigunov, Alexander; Bohuslav, Jan; Tarábková, Hana; Janda, Pavel; Lang, Kamil

2017-08-01

This paper reports the synthesis, characterization, and electrochemical performance of nickel-cobalt hydroxide nanosheets. The hydroxide nanosheets of approximately 0.7nm thickness were prepared by delamination of layered nickel-cobalt hydroxide lactate in water and formed transparent colloids that were stable for months. The nanosheets were deposited on highly oriented pyrolytic graphite by spin coating, and their electrochemical behavior was investigated by cyclic voltammetry in potassium hydroxide electrolyte. Our method of electrode preparation allows for studying the electrochemistry of nanosheets where the majority of the active centers can participate in the charge transfer reaction. The observed electrochemical response was ascribed to mutual compensation of the cobalt and nickel response via electron sharing between these metals in the hydroxide nanosheets, a process that differentiates the behavior of nickel-cobalt hydroxide nanosheets from single nickel hydroxide or cobalt hydroxide nanosheets or their physical mixture. The presence of cobalt in the nickel-cobalt hydroxide nanosheets apparently decreases the time of electrochemical activation of the nanosheet layer, which for the nickel hydroxide nanosheets alone requires more potential sweeps. Copyright © 2017 Elsevier Inc. All rights reserved.

Electrochemical Study of Delta-9-Tetrahydrocannabinol by Cyclic Voltammetry Using Screen Printed Electrode, Improvements in Forensic Analysis

Directory of Open Access Journals (Sweden)

Marco Antonio BALBINO

2016-12-01

Full Text Available Rapid screening of seized drugs is a continuing problem for governmental laboratories and customs agents. Recently new and cheaper methods based on electrochemical sensing have been developed for the detection of illicit drugs. Screen printed electrodes are particularly useful in this regard and can provide excellent sensitivity. In this study, a carbon screen printed electrode for the voltammetric analysis of D9-THC was developed. The analysis was performed using cyclic voltammetry with 0.15 mol×L-1 potassium nitrate as a supporting electrolyte. In the analysis, a D9-THC standard solution was added to the surface electrode by a drop coating method. A study of scan rate, time of pre-concentration, and concentration influence parameters showed versatility during the investigation. The high sensitivity, quantitative capability and low limit of detection (1.0 µmol×L-1 demonstrate that this electrochemical method should be an attractive alternative in forensic investigations of seized samples.

Studies on Me/Al-layered double hydroxides (Me = Ni and Co) as electrode materials for electrochemical capacitors

International Nuclear Information System (INIS)

Liu Xianming; Zhang Yihe; Zhang Xiaogang; Fu Shaoyun

2004-01-01

Me/Al-layered double hydroxides (Me=Ni and Co) prepared by the chemical co-precipitation method have been shown to be outstanding novel materials for electrochemical capacitors. The crystalline structure and the electrochemical properties of the electrodes have been studied by considering the effect of the mole ratio of nickel/cobalt. X-ray diffraction analysis shows that the materials belong to hexagonal system with layered structure. Cyclic voltammetric measurements indicate that Me/Al-layered double hydroxides with the Ni/Co mole ratio of 4:6 exhibit excellent capacitive properties within the potential range of 0.0-0.6 V versus Hg/HgO in 6 mol/L KOH electrolyte. Charge/discharge behaviors have been observed with the highest specific capacitance values of 960 F/g at the current density of 400 mA/g. Impedance studies show that the enhanced electrical properties and high frequency response are attributed to the presence of Co oxides

Management of processes of electrochemical dimensional processing

Science.gov (United States)

Akhmetov, I. D.; Zakirova, A. R.; Sadykov, Z. B.

2017-09-01

In different industries a lot high-precision parts are produced from hard-processed scarce materials. Forming such details can only be acting during non-contact processing, or a minimum of effort, and doable by the use, for example, of electro-chemical processing. At the present stage of development of metal working processes are important management issues electrochemical machining and its automation. This article provides some indicators and factors of electrochemical machining process.

Application of electrochemical optical waveguide lightmode spectroscopy for studying the effect of different stress factors on lactic acid bacteria

Energy Technology Data Exchange (ETDEWEB)

Adanyi, Nora [Central Food Research Institute, H-1537 Budapest, P.O. Box 393 (Hungary)]. E-mail: n.adanyi@cfri.hu; Nemeth, Edina [Central Food Research Institute, H-1537 Budapest, P.O. Box 393 (Hungary); Halasz, Anna [Central Food Research Institute, H-1537 Budapest, P.O. Box 393 (Hungary); Szendro, Istvan [MicroVacuum Ltd., H-1147 Budapest, Kerekgyarto u. 10 (Hungary); Varadi, Maria [Central Food Research Institute, H-1537 Budapest, P.O. Box 393 (Hungary)

2006-07-28

Electrochemical optical waveguide lightmode spectroscopy (EC-OWLS) has been developed to combine evanescent-field optical sensing with electrochemical control of surface adsorption processes. For bioanalytical sensing, a layer of indium tin oxide (ITO) served as both a high-refractive index waveguide and a conductive electrode. In addition, an electrochemical flow-through fluid cuvette was applied, which incorporated working, reference, and counter electrodes, and was compatible with the constraints of optical sensing. The subject of our study was to monitor how the different stress factors (lactic acid, acetic acid and hydrogen peroxide) influence the survival of lactic acid bacteria. The advantage of EC-OWLS technique is that we could carry out kinetic studies on the behaviour of bacteria under stress conditions, and after exposure of lactobacilli to acid and oxidative stress we get faster results about the status of bacteria compared to the traditional quantitative methods. After optimization of the polarization potential used, calibration curve was determined and the sensor response of different rate of living and damaged cells was studied. The bacterial cells were adsorbed in native form on the surface of the sensor by ensuring polarizing potential (1 V) and were exposed to different concentration of acetic acid and hydrogen peroxide solution to 1 h, respectively and the behaviour of bacteria was monitored. Results were compared to traditional micro-assay method.

Application of electrochemical optical waveguide lightmode spectroscopy for studying the effect of different stress factors on lactic acid bacteria

International Nuclear Information System (INIS)

Adanyi, Nora; Nemeth, Edina; Halasz, Anna; Szendro, Istvan; Varadi, Maria

2006-01-01

Electrochemical optical waveguide lightmode spectroscopy (EC-OWLS) has been developed to combine evanescent-field optical sensing with electrochemical control of surface adsorption processes. For bioanalytical sensing, a layer of indium tin oxide (ITO) served as both a high-refractive index waveguide and a conductive electrode. In addition, an electrochemical flow-through fluid cuvette was applied, which incorporated working, reference, and counter electrodes, and was compatible with the constraints of optical sensing. The subject of our study was to monitor how the different stress factors (lactic acid, acetic acid and hydrogen peroxide) influence the survival of lactic acid bacteria. The advantage of EC-OWLS technique is that we could carry out kinetic studies on the behaviour of bacteria under stress conditions, and after exposure of lactobacilli to acid and oxidative stress we get faster results about the status of bacteria compared to the traditional quantitative methods. After optimization of the polarization potential used, calibration curve was determined and the sensor response of different rate of living and damaged cells was studied. The bacterial cells were adsorbed in native form on the surface of the sensor by ensuring polarizing potential (1 V) and were exposed to different concentration of acetic acid and hydrogen peroxide solution to 1 h, respectively and the behaviour of bacteria was monitored. Results were compared to traditional micro-assay method

Evaluation of the Technical-Economic Potential of Particle- Reinforced Aluminum Matrix Composites and Electrochemical Machining

International Nuclear Information System (INIS)

Schubert, A; Hackert-Oschätzchen, M; Lehnert, N; Götze, U; Herold, F; Schmidt, A; Meichsner, G

2016-01-01

Compared to conventional cutting, the processing of materials by electrochemical machining offers some technical advantages like high surface quality, no thermal or mechanical impact on the work piece and preservation of the microstructure of the work piece material. From the economic point of view, the possibility of process parallelization and the absence of any process-related tool wear are mentionable advantages of electrochemical machining. In this study, based on experimental results, it will be evaluated to what extent the electrochemical machining is technically and economically suitable for the finish-machining of particle- reinforced aluminum matrix composites (AMCs). Initial studies showed that electrochemical machining - in contrast to other machining processes - has the potential to fulfil demanding requirements regarding precision and surface quality of products or components especially when applied to AMCs. In addition, the investigations show that processing of AMCs by electrochemical machining requires less energy than the electrochemical machining of stainless steel. Therefore, an evaluation of electrochemically machined AMCs - compared to stainless steel - from a technical and an economic perspective will be presented in this paper. The results show the potential of electro-chemically machined AMCs and contribute to the enhancement of instruments for technical-economic evaluations as well as a comprehensive innovation control. (paper)

Gold nanoparticle-based electrochemical biosensors

International Nuclear Information System (INIS)

Pingarron, Jose M.; Yanez-Sedeno, Paloma; Gonzalez-Cortes, Araceli

2008-01-01

The unique properties of gold nanoparticles to provide a suitable microenvironment for biomolecules immobilization retaining their biological activity, and to facilitate electron transfer between the immobilized proteins and electrode surfaces, have led to an intensive use of this nanomaterial for the construction of electrochemical biosensors with enhanced analytical performance with respect to other biosensor designs. Recent advances in this field are reviewed in this article. The advantageous operational characteristics of the biosensing devices designed making use of gold nanoparticles are highlighted with respect to non-nanostructured biosensors and some illustrative examples are commented. Electrochemical enzyme biosensors including those using hybrid materials with carbon nanotubes and polymers, sol-gel matrices, and layer-by-layer architectures are considered. Moreover, electrochemical immunosensors in which gold nanoparticles play a crucial role in the electrode transduction enhancement of the affinity reaction as well as in the efficiency of immunoreagents immobilization in a stable mode are reviewed. Similarly, recent advances in the development of DNA biosensors using gold nanoparticles to improve DNA immobilization on electrode surfaces and as suitable labels to improve detection of hybridization events are considered. Finally, other biosensors designed with gold nanoparticles oriented to electrically contact redox enzymes to electrodes by a reconstitution process and to the study of direct electron transfer between redox proteins and electrode surfaces have also been treated

Gold nanoparticle-based electrochemical biosensors

Energy Technology Data Exchange (ETDEWEB)

Pingarron, Jose M.; Yanez-Sedeno, Paloma; Gonzalez-Cortes, Araceli [Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040 Madrid (Spain)

2008-08-01

The unique properties of gold nanoparticles to provide a suitable microenvironment for biomolecules immobilization retaining their biological activity, and to facilitate electron transfer between the immobilized proteins and electrode surfaces, have led to an intensive use of this nanomaterial for the construction of electrochemical biosensors with enhanced analytical performance with respect to other biosensor designs. Recent advances in this field are reviewed in this article. The advantageous operational characteristics of the biosensing devices designed making use of gold nanoparticles are highlighted with respect to non-nanostructured biosensors and some illustrative examples are commented. Electrochemical enzyme biosensors including those using hybrid materials with carbon nanotubes and polymers, sol-gel matrices, and layer-by-layer architectures are considered. Moreover, electrochemical immunosensors in which gold nanoparticles play a crucial role in the electrode transduction enhancement of the affinity reaction as well as in the efficiency of immunoreagents immobilization in a stable mode are reviewed. Similarly, recent advances in the development of DNA biosensors using gold nanoparticles to improve DNA immobilization on electrode surfaces and as suitable labels to improve detection of hybridization events are considered. Finally, other biosensors designed with gold nanoparticles oriented to electrically contact redox enzymes to electrodes by a reconstitution process and to the study of direct electron transfer between redox proteins and electrode surfaces have also been treated. (author)

Study on the electrochemical of the metal deposition from ionic liquids for lithium, titanium and dysprosium

International Nuclear Information System (INIS)

Berger, Claudia A.

2017-01-01

The thesis was aimed to the characterization of electrochemically deposited film of lithium, titanium and dysprosium on Au(111) from different ionic liquids, finally dysprosium on neodymium-iron-boron magnate for industrial applications. The investigation of the deposits were performed using cyclic voltametry, in-situ scanning tunneling microscopy, electrochemical quartz microbalance, XPS and Auger electron spectroscopy. The sample preparation is described in detail. The deposition rate showed a significant temperature dependence.

Characterisation of focal liver lesions with contrast enhanced ultrasonography

International Nuclear Information System (INIS)

Dietrich, Christoph F.

2004-01-01

Ultrasound contrast agents (USCA) have improved the detection rate of liver tumours in recent years. Conventional ultrasound has been reported to be relatively unreliable in the characterisation of liver tumours. SonoVue [reg] (Bracco Imaging Spa) has been shown to be particularly advantageous in the differentiation of benign and malignant liver tumours and, therefore, possibly represents a new cost-effective competitive alternative to other liver imaging modalities (e.g. computed tomography and magnetic resonance imaging), thus allowing these important technologies to be available for other indications (e.g. brain, thorax). More detailed and specific liver tumour characterisation is possible in about 80% of liver tumours due to typical vascularity and perfusion patterns. The role of USCA for better characterisation, which is possible through the analysis of flow characteristics in real time, places a particular emphasis on agent use. Contrast enhanced real-time imaging techniques with SonoVue [reg] allow real-time analysis of tumour perfusion in patients with liver lesions. Liver tumours known to be hyperperfused in the arterial phase (e.g. focal nodular hyperplasia, hepatocellular adenoma and carcinoma, and hyperperfused metastases) can be better detected and characterised. Hypoperfused tumours (e.g. liver metastases of the gastrointestinal tract) can be recognised in the portal venous phase as less perfused 'black spots'. In this article we discuss liver tumour characterisation by contrast enhanced ultrasonography

Electrochemical and DFT studies of {beta}-amino-alcohols as corrosion inhibitors for brass

Energy Technology Data Exchange (ETDEWEB)

Gao, Guo [State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116012 (China)]. E-mail: gaogaoguoguo@yahoo.com.cn; Liang, Chenghao [State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116012 (China); Electromechanics and Materials Engineering College, Dalian Maritime University, Dalian 116026 (China)

2007-03-20

The electrochemical performance of 1-diethylamino-propan-2-ol (EAP) and 1,3-bis-diethylamino-propan-2-ol (DEAP) for brass in simulated atmospheric water is evaluated by potentiodynamic curves and electrochemical impedance spectroscopy (EIS). The experimental results show that the investigated compounds, which can effectively retard the anodic dissolution of brass, are anodic inhibitors. Furthermore, the inhibition efficiency of DEAP is higher than that of EAP at the same concentration. This observation is supported by density functional theoretical (DFT) parameters such as the highest occupied molecule energy level (E {sub HOMO}), the lowest unoccupied molecule energy level (E {sub LUMO}), the energy difference ({delta}E) between E {sub HOMO} and E {sub LUMO}, Mulliken charges and the HOMO orbital.

Synthesis of fully and partially sulfonated polyanilines derived from ortanilic acid: An electrochemical and electromicrogravimetric study

International Nuclear Information System (INIS)

Cano Marquez, Abraham Guadalupe; Torres Rodriguez, Luz Maria; Montes Rojas, Antonio

2007-01-01

The electrochemical polymerization of 2-aminobenzene sulfonic acid, also called ortanilic acid (o-ASA), on a gold electrode precoated with polyaniline (PANI), has been carried out. We proved that the electropolymerization of o-ASA is enhanced on PANI electrodes, resulting in thicker films obtained in aqueous media at room temperature. The electrosynthesized film (P(o-ASA)) was characterized by cyclic voltammetry, FTIR and nuclear magnetic resonance. The compensation of P(o-ASA) charge was evaluated using electrochemical quartz crystal microbalance combined with cyclic voltammetry, which showed that the electroneutralization process mainly involves cations. Additionally, copolymers of aniline and o-ASA were electrosynthesized, using a metallic electrode modified with PANI also as a working electrode. The degree of sulfanation of copolymers has been modulated with the proportions of monomers in the electrosynthesis solution. The studies reveal a more important participation of cations in fully sulfonated polyaniline than in partially sulfonated polyaniline

Electrocatalysts and their Supporting Materials for Proton Exchange Membrane Fuel Cells: Activity and Durability Studies

DEFF Research Database (Denmark)

Permyakova, Anastasia Aleksandrovna

of methanol electro-oxidation for ALD deposited Pt films on Si(100) and Pt-Si alloys on Si(100). ALD deposited Pt films on Si(100) were subsequently annealed at various temperatures to obtain Pt-Si alloy film on Si(100). Obtained alloys were subsequently characterised as potentially highly active methanol...... in oxygen reduction, carbon monoxide and methanol electro-oxidation reactions were explored. Employed catalysts were characterized electrochemically and physiochemically using techniques such as: cyclic voltammetry, rotating disk electrode technique, SEM, TEM, EDS, XPS, TGA/DTA, Raman, XRD, FTIR-IR among...... to long-term durability procedures. A significant part of the PhD study involved development of electrochemical instrumentation and techniques, such as: RDE and set-up, oxygen reduction, methanol and CO electrooxidation, long-term durability procedures, etc. The techniques employed by the author were self...

Static and Dynamic Measurement of Dopamine Adsorption in Carbon Fiber Microelectrodes Using Electrochemical Impedance Spectroscopy.

Science.gov (United States)

Rivera-Serrano, Nilka; Pagan, Miraida; Colón-Rodríguez, Joanisse; Fuster, Christian; Vélez, Román; Almodovar-Faria, Jose; Jiménez-Rivera, Carlos; Cunci, Lisandro

2018-02-06

In this study, electrochemical impedance spectroscopy was used for the first time to study the adsorption of dopamine in carbon fiber microelectrodes. In order to show a proof-of-concept, static and dynamic measurements were taken at potentials ranging from -0.4 to 0.8 V versus Ag|AgCl to demonstrate the versatility of this technique to study dopamine without the need of its oxidation. We used electrochemical impedance spectroscopy and single frequency electrochemical impedance to measure different concentrations of dopamine as low as 1 nM. Moreover, the capacitance of the microelectrodes surface was found to decrease due to dopamine adsorption, which is dependent on its concentration. The effect of dissolved oxygen and electrochemical oxidation of the surface in the detection of dopamine was also studied. Nonoxidized and oxidized carbon fiber microelectrodes were prepared and characterized by optical microscopy, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Optimum working parameters of the electrodes, such as frequency and voltage, were obtained for better measurement. Electrochemical impedance of dopamine was determined at different concentration, voltages, and frequencies. Finally, dynamic experiments were conducted using a flow cell and single frequency impedance in order to study continuous and real-time measurements of dopamine.

Electrochemical fabrication and electronic behavior of polypyrrole nano-fiber array devices

International Nuclear Information System (INIS)

Liu Ling; Zhao Yaomin; Jia Nengqin; Zhou Qin; Zhao Chongjun; Yan Manming; Jiang Zhiyu

2006-01-01

Electrochemically active Polypyrrole (PPy) nano-fiber array device was fabricated via electrochemical deposition method using aluminum anodic oxide (AAO) membrane as template. After alkaline treatment electrochemically active PPy nano-fiber lost electrochemical activity, and became electrochemically inactive PPy. The electronic properties of PPy nano-fiber array devices were measured by means of a simple method. It was found that for an indium-tin oxide/electrochemically inactive PPy nano-fiber device, the conductivity of nano-fiber increased with the increase of voltage applied on the two terminals of nano-fiber. The electrochemical inactive PPy nano-fiber might be used as a nano-fiber switching diode. Both Au/electrochemically active PPy and Au/electrochemically inactive PPy nano-fiber devices demonstrate rectifying behavior, and might have been used for further application as nano-rectifiers

Electrochemical fabrication and electronic behavior of polypyrrole nano-fiber array devices

Energy Technology Data Exchange (ETDEWEB)

Ling, Liu [Department of Chemistry, and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Yaomin, Zhao [Department of Chemistry, and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Nengqin, Jia [Department of Chemistry, and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Qin, Zhou [Department of Chemistry, and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Chongjun, Zhao [Photon Craft Project, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences and Japan Science and Technology Agency, Shanghai 201800 (China); Manming, Yan [Department of Chemistry, and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China); Zhiyu, Jiang [Department of Chemistry, and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433 (China)

2006-05-01

Electrochemically active Polypyrrole (PPy) nano-fiber array device was fabricated via electrochemical deposition method using aluminum anodic oxide (AAO) membrane as template. After alkaline treatment electrochemically active PPy nano-fiber lost electrochemical activity, and became electrochemically inactive PPy. The electronic properties of PPy nano-fiber array devices were measured by means of a simple method. It was found that for an indium-tin oxide/electrochemically inactive PPy nano-fiber device, the conductivity of nano-fiber increased with the increase of voltage applied on the two terminals of nano-fiber. The electrochemical inactive PPy nano-fiber might be used as a nano-fiber switching diode. Both Au/electrochemically active PPy and Au/electrochemically inactive PPy nano-fiber devices demonstrate rectifying behavior, and might have been used for further application as nano-rectifiers.

Electrochemical construction

Science.gov (United States)

Einstein, Harry; Grimes, Patrick G.

1983-08-23

An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.

Electrochemical Corrosion of Stainless Steel in Thiosulfate Solutions Relevant to Gold Leaching

Science.gov (United States)

Choudhary, Lokesh; Wang, Wei; Alfantazi, Akram

2016-01-01

This study aims to characterize the electrochemical corrosion behavior of stainless steel in the ammoniacal thiosulfate gold leaching solutions. Electrochemical corrosion response was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy, while the semi-conductive properties and the chemical composition of the surface film were characterized using Mott-Schottky analysis and X-ray photoelectron spectroscopy, respectively. The morphology of the corroded specimens was analyzed using scanning electron microscopy. The stainless steel 316L showed no signs of pitting in the ammoniacal thiosulfate solutions.

Stability of nanocrystalline electrochemically deposited layers

DEFF Research Database (Denmark)

Pantleon, Karen; Somers, Marcel A. J.

2009-01-01

have different microstructure and properties compared to bulk materials and the thermodynamic non-equilibrium state of as-deposited layers frequently results in changes of the microstructure as a function of time and/or temperature. The evolving microstructure affects the functionality and reliability......The technological demand for manufacturing components with complex geometries of micrometer or sub-micrometer dimensions and ambitions for ongoing miniaturization have attracted particular attention to electrochemical deposition methods. Thin layers of electrochemically deposited metals and alloys...... of electrodeposited components, which can be beneficial, as for the electrical conductivity of copper interconnect lines, or detrimental, as for reduced strength of nickel in MEMS applications. The present work reports on in-situ studies of the microstructure stability of as-deposited nanocrystalline Cu-, Ag- and Ni...

Modified porous silicon for electrochemical sensor of para-nitrophenol

Energy Technology Data Exchange (ETDEWEB)

Belhousse, S., E-mail: all_samia_b@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Belhaneche-Bensemra, N., E-mail: nbelhaneche@yahoo.fr [Ecole Nationale Polytechnique (ENP), 10, Avenue Hassen Badi, B.P. 182, 16200, El Harrach, Algiers (Algeria); Lasmi, K., E-mail: kahinalasmi@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Mezaache, I., E-mail: lyeso_44@hotmail.fr [Ecole Nationale Polytechnique (ENP), 10, Avenue Hassen Badi, B.P. 182, 16200, El Harrach, Algiers (Algeria); Sedrati, T., E-mail: tarek_1990m@hotmail.fr [Ecole Nationale Polytechnique (ENP), 10, Avenue Hassen Badi, B.P. 182, 16200, El Harrach, Algiers (Algeria); Sam, S., E-mail: Sabrina.sam@polytechnique.edu [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Tighilt, F.-Z., E-mail: mli_zola@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Gabouze, N., E-mail: ngabouze@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria)

2014-11-15

Highlights: • Hybrid device based on Porous silicon (PSi) and polythiophene (PTh) was prepared. • Three types of PSi/PTh hybrid structures were elaborated: PSi/PTh, oxide/PSi/PTh and Amino-propyltrimethoxysilane (APTMES)/oxide/PSi/PTh. • PTh was grafted on PSi using electrochemical polymerization. • The electrodetection of para-nitrophenol (p-NPh) was performed by cyclic voltammetry. • Oxide/PSi/PTh and APTMES/oxide/PSi/PTh, based electrochemical sensor showed a good response toward p-NPh. - Abstract: Hybrid structures based on polythiophene modified porous silicon was used for the electrochemical detection of para-nitrophenol, which is a toxic derivative of parathion insecticide and it is considered as a major toxic pollutant. The porous silicon was prepared by anodic etching in hydrofluodic acid. Polythiophene films were then grown by electropolymerisation of thiophene monomer on three different surfaces: hydrogenated PSi, oxidized PSi and amine-terminated PSi. The morphology of the obtained structures were observed by scanning electron microscopy and characterized by spectroscopy (FTIR). Cyclic voltammetry was used to study the electrochemical response of proposed structures to para-nitrophenol. The results show a high sensitivity of the sensor and a linearity of the electrochemical response in a large concentration interval ranging from 1.5 × 10{sup −8} M to the 3 × 10{sup −4}M.

Electrochemical capacitance performance of titanium nitride nanoarray

Energy Technology Data Exchange (ETDEWEB)

Xie, Yibing, E-mail: ybxie@seu.edu.cn [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Suzhou Research Institute of Southeast University, Suzhou 215123 (China); Wang, Yong [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Du, Hongxiu [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China); Suzhou Research Institute of Southeast University, Suzhou 215123 (China)

2013-12-01

Highlights: • TiN nanoarray is formed by a nitridation process of TiO{sub 2} in ammonia atmosphere. • TiN nanoarray exhibits much higher EDLC capacitance than TiO{sub 2} nanoarray. • The specific capacitance of TiN nanoarray achieves a high level of 99.7 mF cm{sup −2}. • A flexible solid-state supercapacitor is constructed by TiN nanoarray and PVA gel. -- Abstract: In this study, titanium nitride (TiN) nanoarrays with a short nanotube and long nanopore structure have been prepared by an anodization process of ultra thin titanium foil in ethylene glycol (EG) solution containing ammonium fluoride, subsequent calcination process in an air atmosphere, and final nitridation process in an ammonia atmosphere. The morphology and microstructure characterization has been conducted using field emission scanning electron microscope and X-ray diffraction. The electrochemical properties have been investigated through cyclic voltammetry and electrochemical impedance spectrum measurements. The electrochemical capacitance performance has been investigated by galvanostatic charge–discharge measurements in the acidic, neural and alkali electrolyte solution. Well-defined TiN nanoarrays contribute a much higher capacitance performance than titania (TiO{sub 2}) in the supercapacitor application due to the extraordinarily improved electrical conductivity. Such an electrochemical capacitance can be further enhanced by increasing aspect ratio of TiN nanoarray from short nanotubes to long nanopores. A flexible supercapacitor has been constructed using two symmetrical TiN nanoarray electrodes and a polyvinyl alcohol (PVA) gel electrolyte with H{sub 2}SO{sub 4}–KCl–H{sub 2}O–EG. Such a supercapacitor has a highly improved potential window and still keeps good electrochemical energy storage. TiN nanoarray with a high aspect ratio can act well as an ultra thin film electrode material of flexible supercapacitor to contribute a superior capacitance performance.

Electrochemical, interfacial, and surface studies of the conversion of carbon dioxide to liquid fuels on tin electrodes

Science.gov (United States)

Wu, Jingjie

The electrochemical reduction of carbon dioxide (CO2) into liquid fuels especially coupling with the intermittent renewable electricity offers a promising means of storing electricity in chemical form, which reduces the dependence on fossil fuels and mitigates the negative impact of anthropogenic CO2 emissions on the planet. Although converting CO2 to fuels is not in itself a new concept, the field has not substantially advanced in the last 30 years primarily because of the challenge of discovery of structural electrocatalysts and the development of membrane architectures for efficient collection of reactants and separation of products. An efficient catalyst for the electrochemical conversion of CO2 to fuels must be capable of mediating a proton-coupled electron transfer reaction at low overpotentials, reducing CO2 in the presence of water, selectively converting CO 2 to desirable chemicals, and sustaining long-term operations (Chapter 1). My Ph.D. research was an investigation of the electroreduction of CO2 on tin-based electrodes and development of an electrochemical cell to convert CO2 to liquid fuels. The initial study focused on understanding the CO2 reduction reaction chemistry in the electrical double layer with an emphasis on the effects of electrostatic adsorption of cations, specific adsorption of anion and electrolyte concentration on the potential and proton concentration at outer Helmholtz plane at which reduction reaction occurs. The variation of potential and proton concentration at outer Helmholtz plane accounts for the difference in activity and selectivity towards CO2 reduction when using different electrolytes (Chapter 2). Central to the highly efficient CO2 reduction is an optimum microstructure of catalyst layer in the Sn gas diffusion electrode (GDE) consisting of 100 nm Sn nanoparticles to facilitate gas diffusion and charge transfer. This microstructure in terms of the proton conductor fraction and catalyst layer thickness was optimized to

Bioactivation of diclofenac in vitro and in vivo: correlation to electrochemical studies

DEFF Research Database (Denmark)

Madsen, Kim G; Skonberg, Christian; Jurva, Ulrik

2008-01-01

Diclofenac is widely used in the treatment of, for example, arthritis and muscle pain. The use of diclofenac has been associated with hepatotoxicity, which has been linked to the formation of reactive metabolites. Diclofenac can be metabolized to 4'-OH- and 5-OH-diclofenac, both of which are able...... oxidation of diclofenac to a +16 Da metabolite was shown to be identical to a synthetic standard of 5-OH-diclofenac. Furthermore, two different experimental designs were investigated with respect to the electrochemical oxidation of 4'-OH- and 5-OH-diclofenac. In the first approach, the oxidized sample...... was collected in an aqueous solution of GSH, whereas in the other approach, GSH was added to the sample before the oxidation was performed. From these electrochemical oxidations, a range of GSH conjugates of 4'-OH- and 5-OH-diclofenac were observed and characterized by MS/MS. This allowed the development...

Electrochemical Characterization of a PEMEC Using Impedance Spectroscopy

DEFF Research Database (Denmark)

Elsøe, Katrine; Grahl-Madsen, L.; Hjelm, Johan

2017-01-01

In this study, electrochemical impedance spectroscopy (EIS) is applied in combination with cyclic voltammetry (CV) and current density – cell voltage curves (iV-curves) to investigate the processes contributing to the total impedance of a polymer electrolyte membrane electrolysis cell (PEMEC). i......V-curves were linear above 0.35 A cm−2 implying ohmic processes to be performance limiting, however the impedance spectra showed three arcs indicating three electrochemical reactions at these conditions not to be purely ohmic, but also to have capacitive properties. A hypothesis that the composite Ir...

Electrochemical modification of carbon electrode with benzylphosphonic groups

International Nuclear Information System (INIS)

Benjamin, Ossonon Diby; Weissmann, Martin; Bélanger, Daniel

2014-01-01

Electrochemical modification of carbon electrodes by aryl groups bearing a phosphonate terminal functionality was carried out by both electrochemical reduction of diazonium ions (diazobenzylphosphonic acid) and electrochemical oxidation of an amine (aminobenzylphosphonic acid). The grafting by electrochemical reduction of aryl diazonium ions was found to be more efficient. The surface concentration of phosphonate groups, estimated by electrochemical reduction of electrostatically bound Pb(II) ions, was found to be about 25% higher for the layer formed by electrochemical reduction of diazonium ions than for the layer formed by oxidation of the amine. The acid–base properties of the grafted films were slightly influenced by the grafting procedure and the difference in the apparent pK a was most likely related to the presence of the substrate –NH-aryl linkage for the film generated by amine oxidation. X-ray photoelectron spectroscopy was used to get some insight on the chemical species present at the carbon electrode surface. For both procedures, the films consist in mixture of at least two different covalently grafted species

Superhydrophobic surfaces by electrochemical processes.

Science.gov (United States)

Darmanin, Thierry; Taffin de Givenchy, Elisabeth; Amigoni, Sonia; Guittard, Frederic

2013-03-13

This review is an exhaustive representation of the electrochemical processes reported in the literature to produce superhydrophobic surfaces. Due to the intensive demand in the elaboration of superhydrophobic materials using low-cost, reproducible and fast methods, the use of strategies based on electrochemical processes have exponentially grown these last five years. These strategies are separated in two parts: the oxidation processes, such as oxidation of metals in solution, the anodization of metals or the electrodeposition of conducting polymers, and the reduction processed such as the electrodeposition of metals or the galvanic deposition. One of the main advantages of the electrochemical processes is the relative easiness to produce various surface morphologies and a precise control of the structures at a micro- or a nanoscale. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of nano-particles by soft chemistry: structural, morphological and dimensional control. Studies of the electrochemical properties (towards dyes solar cells)

International Nuclear Information System (INIS)

Cassaignon, S.; Koelsch, M.; Jolivet, J.P.

2006-01-01

In this work are described the electrochemical behaviour of different TiO 2 films (anatase, brookite and rutile) in aqueous solution and the influence of the parameters as the crystal structure and the morphology on the electrochemical answer. To complete this study, the capacity of the double layer has been measured by impedance spectroscopy. Voltage measurements of TiO 2 sensitized by a dye will allow to discuss the reversibility of the system and the rearrangement mechanisms. At last, the influence of the nature of the TiO 2 particles (anatase, rutile and brookite) on the photovoltage has been studied in order to estimate their interest for photovoltaic devices. (O.M.)

Materials Characterisation of Glass/epoxy Composites - Focusing on Process Conditions

DEFF Research Database (Denmark)

Jakobsen, Johnny; Lyckegaard, Anders; Jensen, Erik Appel

2013-01-01

Predicting the behaviour of fibre reinforced polymer composites taking the process conditions into account involves advanced modelling techniques and an extensive materials characterisation. The materials characterisation of a chopped strand mat glass/epoxy composite has been the focus...

Electrochemical studies of the effect of H2 on UO2 dissolution

International Nuclear Information System (INIS)

King, F.; Shoesmith, D.W.

2004-09-01

This report summarises evidence for the effect of H 2 on the oxidation and dissolution of UO 2 derived from electrochemical studies. In the presence of γ-radiation or with SIMFUEL electrodes containing ε-particles, the corrosion potential (E CORR ) of UO 2 is observed to be suppressed in the presence of H 2 by up to several hundred milli volts. This effect has been observed at room temperature with 5 MPa H 2 (in the case of γ-irradiated solutions) and at 60 deg C with a H 2 partial pressure of only 0.002-0.014 MPa H 2 with the SIMFUEL electrode. The suppression of E CORR in the presence of H 2 indicates that the degree of surface oxidation and the rate of dissolution of UO 2 is lower in the presence of H 2 .The precise mechanism of the effect of H 2 is unclear at this time. The mechanism appears to involve a surface heterogeneous process, rather than a homogeneous solution process. Under some circumstances the value of E CORR approaches the equilibrium potential for the H 2 /H + couple, suggesting galvanic coupling between sites on which this electrochemical process is catalysed and the rest of the UO 2 surface. It is also possible that H* radical species, either produced radiolytically from H 2 O or by dissociation of H 2 on ε-particles or surface-active UO 2+x sites, reduce oxidised U(V)/U(VI) surface states to U(IV). The effect of H 2 on reducing the degree of surface oxidation is only partially reversible, since surfaces reduced in H 2 atmospheres (re-)oxidise more slowly and to a lesser degree than surfaces not previously exposed to H 2 . Homogeneous reactions between dissolved H 2 and either oxidants or dissolved U(VI) cannot explain the observed effects.Regardless of the precise mechanism, the suppression of the degree of surface oxidation results in lower UO 2 dissolution rates in the presence of H 2 . Application of an electro-chemical dissolution model to the observed E CORR values suggests that the fractional dissolution rate of used fuel in the

Superficially located enlarged lymphoid follicles characterise nodular gastritis.

Science.gov (United States)

Okamura, Takuma; Sakai, Yasuhiro; Hoshino, Hitomi; Iwaya, Yugo; Tanaka, Eiji; Kobayashi, Motohiro

2015-01-01

Nodular gastritis is a form of chronic Helicobacter pylori gastritis affecting the gastric antrum and characterised endoscopically by the presence of small nodular lesions resembling gooseflesh. It is generally accepted that hyperplasia of lymphoid follicles histologically characterises nodular gastritis; however, quantitative analysis in support of this hypothesis has not been reported. Our goal was to determine whether nodular gastritis is characterised by lymphoid follicle hyperplasia.The number, size, and location of lymphoid follicles in nodular gastritis were determined and those properties compared to samples of atrophic gastritis. The percentages of high endothelial venule (HEV)-like vessels were also evaluated.The number of lymphoid follicles was comparable between nodular and atrophic gastritis; however, follicle size in nodular gastritis was significantly greater than that seen in atrophic gastritis. Moreover, lymphoid follicles in nodular gastritis were positioned more superficially than were those in atrophic gastritis. The percentage of MECA-79 HEV-like vessels was greater in areas with gooseflesh-like lesions in nodular versus atrophic gastritis.Superficially located hyperplastic lymphoid follicles characterise nodular gastritis, and these follicles correspond to gooseflesh-like nodular lesions observed endoscopically. These observations suggest that MECA-79 HEV-like vessels could play at least a partial role in the pathogenesis of nodular gastritis.

Electrochemical modeling of hydrogen storage in hydride-forming electrodes

NARCIS (Netherlands)

Ledovskikh, A.; Danilov, D.; Vermeulen, P.; Notten, P.H.L.

2009-01-01

An electrochemical kinetic model (EKM) is developed, describing the electrochemical hydrogen storage in hydride-forming materials under equilibrium conditions. This model is based on first principles of electrochemical reaction kinetics and statistical thermodynamics and describes the complex,

Electrochemically induced transformation of NiS nanoparticles into Ni(OH)2 in KOH aqueous solution toward electrochemical capacitors

International Nuclear Information System (INIS)

Hou Linrui; Yuan Changzhou; Li Diankai; Yang Long; Shen Laifa; Zhang Fang; Zhang Xiaogang

2011-01-01

Highlights: → NiS is synthesized by means of the H 2 O/CS 2 interface under hydrothermal treatment. → NiS itself owns poor electrochemical capacitance in 2 M KOH solution. → NiS is electrochemically induced and transformed into electroactive Ni(OH) 2 . → Ni(OH) 2 is responsible for good energy storage of the NiS in the KOH solution. → The new formed Ni(OH) 2 delivers large energy density at high rates. - Abstract: Nickel sulfide nanoparticles (NPs) are first synthesized by virtue of a unique H 2 O/CS 2 interface under mild hydrothermal treatment. Electrochemical data reveals that the as-synthesized NiS NPs themselves own poor supercapacitive behavior at initial cyclic voltammetry (CV) cycles in 2 M KOH solution, while a specific capacitance of 893 F g -1 can be surprisingly obtained at a current density of 5 A g -1 just after continuous 320 CV cycles. X-ray diffraction and Fourier transform infrared techniques demonstrate that what is really responsible for the good electrochemical capacitance in the KOH aqueous solution is the new electrochemically formed Ni(OH) 2 phase, rather than NiS NPs themselves. The Ni(OH) 2 is slowly formed during the continuous CV cycling process, in which the electrochemically induced phase transformation from NiS to Ni(OH) 2 phase takes place. Furthermore, the new Ni(OH) 2 phase demonstrates the great ability of delivering large specific capacitance at high rates.

Ionic Liquid Catalyzed Electrolyte for Electrochemical Polyaniline Supercapacitors

Science.gov (United States)

Inamdar, A. I.; Im, Hyunsik; Jung, Woong; Kim, Hyungsang; Kim, Byungchul; Yu, Kook-Hyun; Kim, Jin-Sang; Hwang, Sung-Min

2013-05-01

The effect of different wt.% of ionic liquid "1,6-bis (trimethylammonium-1-yl) hexane tetrafluoroborate" in 0.5 M LiClO4+PC electrolyte on the supercapacitor properties of polyaniline (PANI) thin film are investigated. The PANI film is synthesized using electropolymerization of aniline in the presence of sulfuric acid. The electrochemical properties of the PANI thin film are studied by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) measurements. The optimum amount of the ionic liquid is found to be 2 wt.% which provides better ionic conductivity of the electrolyte. The highest specific capacitance of 259 F/g is obtained using the 2 wt.% electrolyte. This capacitance remains at up to 208 F/g (80% capacity retention) after 1000 charge-discharge cycles at a current density of 0.5 mA/g. The PANI film in the 2 wt.% ionic liquid catalyzed 0.5 M LiClO4+PC electrolyte shows small electrochemical resistance, better rate performance and higher cyclability. The increased ionic conductivity of the 2 wt.% ionic liquid catalyzed electrolyte causes a reduction in resistance at the electrode/electrolyte interface, which can be useful in electrochemically-preferred power devices for better applicability.

Smart electrochemical biosensors: From advanced materials to ultrasensitive devices

Energy Technology Data Exchange (ETDEWEB)

Sadik, Omowunmi A., E-mail: osadik@binghamton.ed [Department of Chemistry, Center for Advanced Sensors and Environmental Monitoring (CASE), State University of New York-Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States); Mwilu, Samuel K.; Aluoch, Austin [Department of Chemistry, Center for Advanced Sensors and Environmental Monitoring (CASE), State University of New York-Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States)

2010-05-30

The specificity, simplicity, and inherent miniaturization afforded by advances in modern electronics have allowed electrochemical sensors to rival the most advanced optical protocols. One major obstacle in implementing electrochemistry for studying biomolecular reaction is its inadequate sensitivity. Recent reports however showed unprecedented sensitivities for biomolecular recognition using enhanced electronic amplification provided by new classes of electrode materials (e.g. carbon nanotubes, metal nanoparticles, and quantum dots). Biosensor technology is one area where recent advances in nanomaterials are pushing the technological limits of electrochemical sensitivities, thus allowing for the development of new sensor chemistries and devices. This work focuses on our recent work, based on metal-enhanced electrochemical detection, and those of others in combining advanced nanomaterials with electrochemistry for the development of smart sensors for proteins, nucleic acids, drugs and cancer cells.

Smart electrochemical biosensors: From advanced materials to ultrasensitive devices

International Nuclear Information System (INIS)

Sadik, Omowunmi A.; Mwilu, Samuel K.; Aluoch, Austin

2010-01-01

The specificity, simplicity, and inherent miniaturization afforded by advances in modern electronics have allowed electrochemical sensors to rival the most advanced optical protocols. One major obstacle in implementing electrochemistry for studying biomolecular reaction is its inadequate sensitivity. Recent reports however showed unprecedented sensitivities for biomolecular recognition using enhanced electronic amplification provided by new classes of electrode materials (e.g. carbon nanotubes, metal nanoparticles, and quantum dots). Biosensor technology is one area where recent advances in nanomaterials are pushing the technological limits of electrochemical sensitivities, thus allowing for the development of new sensor chemistries and devices. This work focuses on our recent work, based on metal-enhanced electrochemical detection, and those of others in combining advanced nanomaterials with electrochemistry for the development of smart sensors for proteins, nucleic acids, drugs and cancer cells.

Electrochemical capacitor

Science.gov (United States)

Anderson, Marc A.; Liu, Kuo -Chuan; Mohr, Charles M.

1999-10-05

An inexpensive porous metal oxide material having high surface area, good conductivity and high specific capacitance is advantageously used in an electrochemical capacitor. The materials are formed in a sol-gel process which affords control over the properties of the resultant metal oxide materials.

Characterisation of hydrides in a zirconium alloy, by EBSD

International Nuclear Information System (INIS)

Ubhi, H.S.; Larsen, K.

2012-01-01

Zirconium alloys are used in nuclear reactors owing to their low capture cross-section for thermal neutrons and good mechanical and corrosion properties. However, they do suffer from delayed hydrogen cracking (DHC) due to formation of hydride particles. This study shows how the electron back-scatter diffraction (EBSD) technique can be used to characterise hydrides and their orientation relationship with the matrix. Hydrided EB weld specimens were prepared by electro-polishing, characterised using Oxford instruments AZtecHKL EBSD apparatus and software attached to a FEG SEM. Hydrides were found to exist as fine intra granular plates and having the Blackburn orientation relationship, i.e. (0002)Zr//(111)hydride and (1120)Zr//(1-10)hydride. The hydrides were also found to contain sigma 3 boundaries as well as local misorientations. (author)

Physico-chemical characterisation of material fractions in household waste

DEFF Research Database (Denmark)

Götze, Ramona; Boldrin, Alessio; Scheutz, Charlotte

2016-01-01

State-of-the-art environmental assessment of waste management systems rely on data for the physico-chemical composition of individual material fractions comprising the waste in question. To derive the necessary inventory data for different scopes and systems, literature data from different sources...... and backgrounds are consulted and combined. This study provides an overview of physico-chemical waste characterisation data for individual waste material fractions available in literature and thereby aims to support the selection of data fitting to a specific scope and the selection of uncertainty ranges related...... to the data selection from literature. Overall, 97 publications were reviewed with respect to employed characterisation method, regional origin of the waste, number of investigated parameters and material fractions and other qualitative aspects. Descriptive statistical analysis of the reported physico...

Elaboration and characterisation of plutonium waste reference materials

International Nuclear Information System (INIS)

Perolat, J.P.

1990-01-01

The Analysis Methods Establishment Commission (CETAMA) has set up a program for the elaboration and characterisation of plutonium waste reference materials. The object of this program is to give laboratories the possibility to test and calibrate apparatus used in non-destructive methods for the analysis of plutonium waste. The different parameters of this program are presented: - characterisation of plutonium, - type and number of containers, - plutonium distribution inside the different containers, - description of the matrix

Morphological and electrochemical studies of spherical boron doped diamond electrodes

Energy Technology Data Exchange (ETDEWEB)

Mendes de Barros, R.C. [IQ/USP, Av. Lineu Prestes, 748, Bloco 2 Superior, Cidade Universitaria, Sao Paulo/SP, 05508-900 (Brazil); Ferreira, N.G. [LAS/INPE, Av. dos Astronautas, 1758, Jardim da Granja, Sao Jose dos Campos/SP, 12245-970 (Brazil); Azevedo, A.F. [LAS/INPE, Av. dos Astronautas, 1758, Jardim da Granja, Sao Jose dos Campos/SP, 12245-970 (Brazil); Corat, E.J. [LAS/INPE, Av. dos Astronautas, 1758, Jardim da Granja, Sao Jose dos Campos/SP, 12245-970 (Brazil); Sumodjo, P.T.A. [IQ/USP, Av. Lineu Prestes, 748, Bloco 2 Superior, Cidade Universitaria, Sao Paulo/SP, 05508-900 (Brazil); Serrano, S.H.P. [IQ/USP, Av. Lineu Prestes, 748, Bloco 2 Superior, Cidade Universitaria, Sao Paulo/SP, 05508-900 (Brazil)]. E-mail: shps@iq.usp.br

2006-08-14

Morphological and electrochemical characteristics of boron doped diamond electrode in new geometric shape are presented. The main purpose of this study is a comparison among voltammetric behavior of planar glassy carbon electrode (GCE), planar boron doped diamond electrode (PDDE) and spherical boron doped diamond electrode (SDDE), obtained from similar experimental parameters. SDDE was obtained by the growth of boron doped film on textured molybdenum tip. This electrode does not present microelectrode characteristics. However, its voltammetric peak current, determined at low scan rates, is largest associated to the smallest {delta}E {sub p} values for ferrocyanide system when compared with PDDE or GCE. In addition, the capacitance is about 200 times smaller than that for GCE. These results show that the analytical performance of boron doped diamond electrodes can be implemented just by the change of sensor geometry, from plane to spherical shape.

Electrochemical synthesis of poly(pyrrole-co-o-anisidine)/chitosan composite films

Science.gov (United States)

Yalçınkaya, Süleyman; Çakmak, Didem

2017-05-01

In this study, poly(pyrrole-co-o-anisidine)/chitosan composite films were electrochemically synthesized in various monomers feed ratio (pyrrole: o-anisidine; 9:1, 7:3, 1:1, 3:7 and 1:9) of pyrrole and o-anisidine on the platinum electrode. Electrochemical synthesis of the composite films was carried out via cyclic voltammetry technique. They were characterized by FT-IR, cyclic voltammetry, SEM micrographs, digital images, TGA and DSC techniques. The SEM results indicated that the particle size of the composite decreased with increasing o-anisidine ratio and the films became more likely to be smooth morphology. The TGA results proved that the film of the composite with 1:1 ratio showed highest final degradation temperature and lowest weight loss (83%) compared to copolymer and 9:1 1:9 composite films. The 1:1 composite film had higher thermal stability than copolymer and the other composite films (9:1 1:9). Meanwhile, electrochemical studies exhibited that the 1/9 composite film had good electrochemical stability as well.

Towards a complete characterisation of guaiacwood oil.

Science.gov (United States)

Tissandié, Loïc; Viciana, Stéphane; Brevard, Hugues; Meierhenrich, Uwe J; Filippi, Jean-Jacques

2018-05-01

Guaiacwood oil is a common perfume ingredient used in modern compositions for its suave woody-rosy scent. This essential oil is a byproduct of the timber industry obtained by hydrodistillation of the heartwood of Bulnesia sarmientoi, a tree native from Latin America. Despite being widely used in perfumery, guaiacwood oil has been poorly described in the past. This study aims at giving an in-depth characterisation of its chemical composition as well as disclosing the odorant compounds responsible for its characteristic fragrance. Our methodology was based on a combination of fractionation and analytical techniques, including comprehensive two-dimensional gas chromatography coupled to mass spectrometry and preparative capillary-gas chromatography. The entire analytical work led to the isolation of 20 constituents among which 14 have never been reported so far in natural extracts. Each isolated compound was fully characterised by spectroscopic methods. Finally, the accurate knowledge of the chemical composition permitted the identification of the odour-active constituents by gas chromatography-olfactometry. Copyright © 2018 Elsevier Ltd. All rights reserved.