Modern aspects of electrochemistry

CERN Document Server

Vayenas, Constantinos G

2007-01-01

This book covers a broad range of topics in Electrochemistry in an authoritative manner by internationally renowned specialists. Topics include a chapter on the survey of experimental techniques and devices of solid state electrochemistry begun in Volume 39.

Silicon: electrochemistry and luminescence

NARCIS (Netherlands)

Kooij, Ernst Stefan

1997-01-01

The electrochemistry of crystalline and porous silicon and the luminescence from porous silicon has been studied. One chapter deals with a model for the anodic dissolution of silicon in HF solution. In following chapters both the electrochemistry and various ways of generating visible

Electrochemistry and dye-sensitized solar cells

Czech Academy of Sciences Publication Activity Database

Kavan, Ladislav

2017-01-01

Roč. 2, č. 1 (2017), s. 88-98 ISSN 2451-9103 R&D Projects: GA ČR GA13-07724S Institutional support: RVO:61388955 Keywords : electrochemistry * dye-sensitized cells * photoelectrode Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis)

Interaction distances in oxides, sulfides and selenides with face-centered packing

International Nuclear Information System (INIS)

Kesler, Ya.A.

1993-01-01

Concept of characteristic distances (CD) was specified with account of the principle of topologically face-centered anion packing: calculation method was presented and boundary conditions of CD concept applicability were considered. Tables of CD in oxides, sulfides and selenides, obtained in result of self-consistent calculations on the basis of experimental crystallographic data, are presented. Pair correlations between CD in oxides, sulfides and selenides were considered, their relationship with cation electron structure was established. Peculiarities of chemical bond in oxides, sulfides and selenides with face-centered anion packing were discussed

Green Hydroselenation of Aryl Alkynes: Divinyl Selenides as a Precursor of Resveratrol

Directory of Open Access Journals (Sweden)

Gelson Perin

2017-02-01

Full Text Available A simple and efficient protocol to prepare divinyl selenides has been developed by the regio- and stereoselective addition of sodium selenide species to aryl alkynes. The nucleophilic species was generates in situ, from the reaction of elemental selenium with NaBH4, utilizing PEG-400 as the solvent. Several divinyl selenides were obtained in moderate to excellent yields with selectivity for the (Z,Z-isomer by a one-step procedure that was carried out at 60 °C in short reaction times. The methodology was extended to tellurium, giving the desired divinyl tellurides in good yields. Furthermore, the Fe-catalyzed cross-coupling reaction of bis(3,5-dimethoxystyryl selenide 3f with (4-methoxyphenylmagnesium bromide 5 afforded resveratrol trimethyl ether 6 in 57% yield.

Green Hydroselenation of Aryl Alkynes: Divinyl Selenides as a Precursor of Resveratrol.

Science.gov (United States)

Perin, Gelson; Barcellos, Angelita M; Luz, Eduardo Q; Borges, Elton L; Jacob, Raquel G; Lenardão, Eder J; Sancineto, Luca; Santi, Claudio

2017-02-20

A simple and efficient protocol to prepare divinyl selenides has been developed by the regio- and stereoselective addition of sodium selenide species to aryl alkynes. The nucleophilic species was generates in situ , from the reaction of elemental selenium with NaBH₄, utilizing PEG-400 as the solvent. Several divinyl selenides were obtained in moderate to excellent yields with selectivity for the ( Z , Z )-isomer by a one-step procedure that was carried out at 60 °C in short reaction times. The methodology was extended to tellurium, giving the desired divinyl tellurides in good yields. Furthermore, the Fe-catalyzed cross-coupling reaction of bis(3,5-dimethoxystyryl) selenide 3f with (4-methoxyphenyl)magnesium bromide 5 afforded resveratrol trimethyl ether 6 in 57% yield.

Asymmetric supercapacitors with metal-like ternary selenides and porous graphene electrodes

KAUST Repository

Xia, Chuan; Jiang, Qiu; Zhao, Chao; Beaujuge, Pierre; Alshareef, Husam N.

2016-01-01

nanostructured ternary nickel cobalt selenides result in a much higher areal capacitance (2.33 F cm−2 at 4 mA cm−2), better rate performance and cycling stability than their binary selenide equivalents, and other ternary oxides and chalcogenides. Those hybrid

Selenide isotope generator for the Galileo mission

International Nuclear Information System (INIS)

Goebel, C.J.; Hammel, T.E.

1978-01-01

A significantly improved thermoelectric generator has been developed to provide electric power for NASA's Galileo Mission in 1982. Nominal power requirements for Galileo will be about 450 watts at BOL (Beginning of Life), and this will be furnished by two Selenide Isotope Generators (SIG) each powered by a Multi Hundred Watt (MHW) radioisotopic heat source. A Ground Demonstration System (GDS) of a nominal 100 w(e) features a 3M - produced selenide ring module around a shortened MHW-dimensioned electrical heat source, newly developed axially-grooved heat pipes on a disc-shaped radiator, and other innovations which will allow a full-sized generator's weight to be held at about 90 lbs

Slow recombination centers in cadmium selenide monocrystalline films

International Nuclear Information System (INIS)

Smyntyna, V.A.

1983-01-01

As a result of annealing when concentration of selenium Vacancies decreases due to their diffusion towards the surface, show recombination K-centers begin to influence the photoelectric properties of monocrystalline cadmium selenide layers. Energy levels of K-centers are located by 0.23-0.25 eV over the valent zone ceiling. The nature of K-centers is determined by the presence in the cadmium selenide layer structure of intrisic defects-cadmium vacancies in contrast to r-centers of slow recombination which are bound with impurities in a semiconductor material

Vapor transport deposition of antimony selenide thin film solar cells with 7.6% efficiency.

Science.gov (United States)

Wen, Xixing; Chen, Chao; Lu, Shuaicheng; Li, Kanghua; Kondrotas, Rokas; Zhao, Yang; Chen, Wenhao; Gao, Liang; Wang, Chong; Zhang, Jun; Niu, Guangda; Tang, Jiang

2018-06-05

Antimony selenide is an emerging promising thin film photovoltaic material thanks to its binary composition, suitable bandgap, high absorption coefficient, inert grain boundaries and earth-abundant constituents. However, current devices produced from rapid thermal evaporation strategy suffer from low-quality film and unsatisfactory performance. Herein, we develop a vapor transport deposition technique to fabricate antimony selenide films, a technique that enables continuous and low-cost manufacturing of cadmium telluride solar cells. We improve the crystallinity of antimony selenide films and then successfully produce superstrate cadmium sulfide/antimony selenide solar cells with a certified power conversion efficiency of 7.6%, a net 2% improvement over previous 5.6% record of the same device configuration. We analyze the deep defects in antimony selenide solar cells, and find that the density of the dominant deep defects is reduced by one order of magnitude using vapor transport deposition process.

Applications of electrochemistry in medicine

CERN Document Server

Schlesinger, Mordechay

2013-01-01

Medical Applications of Electrochemistry, a volume of the series Modern Aspects of Electrochemistry, illustrates the interdisciplinary nature of modern science by indicating the many current issues in medicine that are susceptible to solution by electrochemical methods. This book also suggests how personalized medicine can develop.

Fabrication, characterization and applications of iron selenide

Energy Technology Data Exchange (ETDEWEB)

Hussain, Raja Azadar, E-mail: hussainazadar@yahoo.com [Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Badshah, Amin [Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Lal, Bhajan [Department of Energy Systems Engineering, Sukkur Institute of Business Administration (Pakistan)

2016-11-15

This review article presents fabrication of FeSe by solid state reactions, solution chemistry routes, chemical vapor deposition, spray pyrolysis and chemical vapor transport. Different properties and applications such as crystal structure and phase transition, band structure, spectroscopy, superconductivity, photocatalytic activity, electrochemical sensing, and fuel cell activity of FeSe have been discussed. - Graphical abstract: Iron selenide can be synthesized by solid state reactions, chemical vapor deposition, solution chemistry routes, chemical vapor transport and spray pyrolysis. - Highlights: • Different fabrication methods of iron selenide (FeSe) have been reviewed. • Crystal structure, band structure and spectroscopy of FeSe have been discussed. • Superconducting, catalytic and fuel cell application of FeSe have been presented.

Condensed matter physics in electrochemistry

International Nuclear Information System (INIS)

Kornyshev, A.A.

1991-01-01

Some topics in electrochemistry are considered from the condensed matter physics viewpoint in relation to the problems discussed in this book. Examples of the successful application of condensed matter physics to electrochemistry are discussed together with prospective problems and pressing questions. (author). 127 refs, 4 figs

PROPERTIES AND OPTICAL APPLICATION OF POLYCRYSTALLINE ZINC SELENIDE OBTAINED BY PHYSICAL VAPOR DEPOSITION

Directory of Open Access Journals (Sweden)

A. A. Dunaev

2015-05-01

Full Text Available Findings on production technology, mechanical and optical properties of polycrystalline zinc selenide are presented. The combination of its physicochemical properties provides wide application of ZnSe in IR optics. Production technology is based on the method of physical vapor deposition on a heated substrate (Physical Vapor Deposition - PVD. The structural features and heterogeneity of elemental composition for the growth surfaces of ZnSe polycrystalline blanks were investigated using CAMEBAX X-ray micro-analyzer. Characteristic pyramid-shaped crystallites were recorded for all growth surfaces. The measurements of the ratio for major elements concentrations show their compliance with the stoichiometry of the ZnSe compounds. Birefringence, optical homogeneity, thermal conductivity, mechanical and optical properties were measured. It is established that regardless of polycrystalline condensate columnar and texturing, the optical material is photomechanically isotropic and homogeneous. The actual performance of parts made of polycrystalline optical zinc selenide in the thermal spectral ranges from 3 to 5 μm and from 8 to 14 μm and in the CO2 laser processing plants with a power density of 500 W/cm2 is shown. The developed technology gives the possibility to produce polycrystalline optical material on an industrial scale.

Comparative electrochemistry of technetium (V) and rhenium (V) dioxo complexes

International Nuclear Information System (INIS)

Kremer, C.; Kremer, E.; Dominguez, S.; Mederos, A.

1996-01-01

The heavy use of 99m Tc in nuclear medicine and the recent development of 188 Re radiopharmaceuticals have encouraged the comparative study of Tc and Re coordination compounds. In this work, the electrochemistry of [M v O 2 (amine) 2 ] + (M = Tc, Re; amine = ethylenediamine, 1,3-diaminopropane, diethylenetriamine, triethylenetetramine) complexes is studied by cyclic voltammetry and the results are compared. The voltammograms of these compounds, obtained at different pH values, show that [ReO 2 (amine) 2 + cations are thermodynamically stable even when protonated. On the other hand, analogous Tc compounds are not so stable and easily decompose if existing as [TcO (OH) (amine) 2 ] 2+ . (author). 17 refs., 3 figs., 1 tab

Instrumental methods in electrochemistry

CERN Document Server

Pletcher, D; Peat, R

2010-01-01

Using 372 references and 211 illustrations, this book underlines the fundamentals of electrochemistry essential to the understanding of laboratory experiments. It treats not only the fundamental concepts of electrode reactions, but also covers the methodology and practical application of the many versatile electrochemical techniques available.Underlines the fundamentals of electrochemistry essential to the understanding of laboratory experimentsTreats the fundamental concepts of electrode reactionsCovers the methodology and practical application of the many ve

11. SIBEE: Brazilian symposium on electrochemistry and electro analytics

International Nuclear Information System (INIS)

1999-01-01

Theoretical and experimental papers are presented in these proceedings on the following subjects: fundamental electrochemistry, energy electrochemical conversion, electro catalysis, corrosion, polymers, molecular electrochemistry and bio electrochemistry

National symposium on electrochemistry in nuclear technology

International Nuclear Information System (INIS)

1994-01-01

A National Symposium on Electrochemistry in Nuclear Technology (NASENT-94) was held at Kalpakkam, India during January 5-7, 1994. The subjects covered a wide range of topics in electrochemistry, such as electrochemical production, refining, analysis and corrosion of metals, electrochemical monitors and sensors, solid state electrochemistry, applications of electrochemical processes and measurement techniques in nuclear technology etc. Papers relevant to INIS are indexed separately

Chemical Potential Tuning and Enhancement of Thermoelectric Properties in Indium Selenides.

Science.gov (United States)

Rhyee, Jong-Soo; Kim, Jin Hee

2015-03-20

Researchers have long been searching for the materials to enhance thermoelectric performance in terms of nano scale approach in order to realize phonon-glass-electron-crystal and quantum confinement effects. Peierls distortion can be a pathway to enhance thermoelectric figure-of-merit ZT by employing natural nano-wire-like electronic and thermal transport. The phonon-softening known as Kohn anomaly, and Peierls lattice distortion decrease phonon energy and increase phonon scattering, respectively, and, as a result, they lower thermal conductivity. The quasi-one-dimensional electrical transport from anisotropic band structure ensures high Seebeck coefficient in Indium Selenide. The routes for high ZT materials development of In₄Se₃ - δ are discussed from quasi-one-dimensional property and electronic band structure calculation to materials synthesis, crystal growth, and their thermoelectric properties investigations. The thermoelectric properties of In₄Se₃ - δ can be enhanced by electron doping, as suggested from the Boltzmann transport calculation. Regarding the enhancement of chemical potential, the chlorine doped In₄Se₃ - δ Cl 0.03 compound exhibits high ZT over a wide temperature range and shows state-of-the-art thermoelectric performance of ZT = 1.53 at 450 °C as an n -type material. It was proven that multiple elements doping can enhance chemical potential further. Here, we discuss the recent progress on the enhancement of thermoelectric properties in Indium Selenides by increasing chemical potential.

{sup 77} Se NMR of deuteride vinyl and acetylene selenides; RMn de {sup 77} Se de selenetos vinilicos e acetilenicos deuterados

Energy Technology Data Exchange (ETDEWEB)

Roque, L C; Stefani, H A; Arruda Campos, I.P. de; Comasseto, J V [Sao Paulo Univ., SP (Brazil). Inst. de Quimica

1992-12-31

The main objective of this work is a contribution for establishing a data base sufficient for interpretation of the selenium organic compound spectra. Due to the short literature on acetylene and vinyl selenides, the investigation of these compounds using {sup 77} Se NMR has been considered interesting. Particularly, compounds containing the selenium phenyl group have been selected, as they are larger used in organic chemistry. Non usual deuterated compounds have been applied, viewing simplification of the experimental results interpretation, since the use of deuterium virtually eliminates the Se-H coupling constants, due to the protons of the selenium phenyl group 5 refs., 2 tabs.

Ex situ formation of metal selenide quantum dots using bacterially derived selenide precursors

International Nuclear Information System (INIS)

Fellowes, J W; Pattrick, R A D; Lloyd, J R; Charnock, J M; Coker, V S; Mosselmans, J F W; Weng, T-C; Pearce, C I

2013-01-01

Luminescent quantum dots were synthesized using bacterially derived selenide (Se II− ) as the precursor. Biogenic Se II− was produced by the reduction of Se IV by Veillonella atypica and compared directly against borohydride-reduced Se IV for the production of glutathione-stabilized CdSe and β-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological Se II− formed smaller, narrower size distributed QDs under the same conditions. The growth kinetics of biologically sourced CdSe phases were slower. The proteins isolated from filter sterilized biogenic Se II− included a methylmalonyl-CoA decarboxylase previously characterized in the closely related Veillonella parvula. XAS analysis of the glutathione-capped CdSe at the S K-edge suggested that sulfur from the glutathione was structurally incorporated within the CdSe. A novel synchrotron based XAS technique was also developed to follow the nucleation of biological and inorganic selenide phases, and showed that biogenic Se II− is more stable and more resistant to beam-induced oxidative damage than its inorganic counterpart. The bacterial production of quantum dot precursors offers an alternative, ‘green’ synthesis technique that negates the requirement of expensive, toxic chemicals and suggests a possible link to the exploitation of selenium contaminated waste streams. (paper)

Ex Situ Formation of Metal Selenide Quantum Dots Using Bacterially Derived Selenide Precursors

Energy Technology Data Exchange (ETDEWEB)

Fellowes, Jonathan W.; Pattrick, Richard; Lloyd, Jon; Charnock, John M.; Coker, Victoria S.; Mosselmans, JFW; Weng, Tsu-Chien; Pearce, Carolyn I.

2013-04-12

Luminescent quantum dots were synthesized using bacterially derived selenide (SeII-) as the precursor. Biogenic SeII- was produced by the reduction of Se-IV by Veillonella atypica and compared directly against borohydride-reduced Se-IV for the production of glutathione-stabilized CdSe and beta-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological SeII- formed smaller, narrower size distributed QDs under the same conditions. The growth kinetics of biologically sourced CdSe phases were slower. The proteins isolated from filter sterilized biogenic SeII- included a methylmalonyl-CoA decarboxylase previously characterized in the closely related Veillonella parvula. XAS analysis of the glutathione-capped CdSe at the S K-edge suggested that sulfur from the glutathione was structurally incorporated within the CdSe. A novel synchrotron based XAS technique was also developed to follow the nucleation of biological and inorganic selenide phases, and showed that biogenic SeII- is more stable and more resistant to beam-induced oxidative damage than its inorganic counterpart. The bacterial production of quantum dot precursors offers an alternative, 'green' synthesis technique that negates the requirement of expensive, toxic chemicals and suggests a possible link to the exploitation of selenium contaminated waste streams.

Biomass electrochemistry : from cellulose to sorbitol

NARCIS (Netherlands)

Kwon, Youngkook

2013-01-01

The primary goal of this thesis is to study the potential role of electrochemistry in finding new routes for sustainable chemicals from biomass in aqueous-phase solutions. In order to assess the potential of electrochemistry in biomass conversion, we developed an online HPLC system by using a

Imaging mass spectrometry tackles interfacial challenges in electrochemistry

Energy Technology Data Exchange (ETDEWEB)

Yu, Xiao-Ying

2017-12-01

Electrochemistry has played a significant role in many research fields. Owing to its sensitivity and selectivity, in situ electroanalysis has been widely used as a fast and economical means for achieving outstanding results. Although many spectroscopic techniques have been used in electrochemistry, the challenges to capture short-lived intermediate species as a result of electron transfer in the buried solid electrode and electrolyte solution interface remains a grand challenge. In situ imaging mass spectrometry (IMS) recently has been extended to capture transient species in electrochemistry. This review intends to summarize newest development of IMS and its applications in advancing fundamental electrochemistry.

Assessment of fibrous insulation materials for the selenide isotope generator system

International Nuclear Information System (INIS)

Wei, G.C; Tennery, V.J.

1977-11-01

Fibrous insulations for use in the converter and the heat source of the radioisotope-powered, selenide element, thermoelectric generator (selenide isotope generator) are assessed. The most recent system design and material selection basis is presented. Several fibrous insulation materials which have the potential for use as load-bearing or nonload-bearing thermal insulations are reviewed, and thermophysical properties supplied by manufacturers or published in the literature are presented. Potential problems with the application of fibrous insulations in the selenide isotope generator are as follows: compatibility with graphite, the thermoelectric elements, and the isolation hot frame; devitrification, grain growth, and sintering with an accompanying degradation of insulation quality; impurity diffusion from the insulation to adjoining structures; outgassing and storage of fibrous materials. Areas in which thermophysical data or quantitative information on the insulation and structural stability is lacking are identified

Factors that Prevent Learning in Electrochemistry

Science.gov (United States)

Schmidt, Hans-Jurgen; Marohn, Annette; Harrison, Allan G.

2007-01-01

Electrochemistry plays an important role in curricula, textbooks, and in everyday life. The purpose of the present study was to identify and understand secondary-school students' problems in learning electrochemistry at an introductory chemistry level. The investigation covered four areas: (a) electrolytes, (b) transport of electric charges in…

Low-energy electron energy losses and inelastic mean free paths in zinc, selenium, and zinc selenide

Energy Technology Data Exchange (ETDEWEB)

Bourke, J.D.; Chantler, C.T., E-mail: chantler@unimelb.edu.au

2014-10-15

We compute low-energy optical energy loss spectra for the elemental solids zinc and selenium, and for the binary compound zinc selenide. The optical data are transformed via a constrained partial-pole algorithm to produce momentum-dependent electron energy loss spectra and electron inelastic mean free paths. This enables a comparison between the electron scattering behaviour in a compound solid and its constituent elements. Results cannot be explained by aggregation methods or commonly used universal curves, and prove that new approaches are required. Our work demonstrates new capabilities for the determination of fundamental material properties for a range of structures previously inaccessible to established theoretical models, and at energy levels inaccessible to most experimental techniques.

Low-energy electron energy losses and inelastic mean free paths in zinc, selenium, and zinc selenide

International Nuclear Information System (INIS)

Bourke, J.D.; Chantler, C.T.

2014-01-01

We compute low-energy optical energy loss spectra for the elemental solids zinc and selenium, and for the binary compound zinc selenide. The optical data are transformed via a constrained partial-pole algorithm to produce momentum-dependent electron energy loss spectra and electron inelastic mean free paths. This enables a comparison between the electron scattering behaviour in a compound solid and its constituent elements. Results cannot be explained by aggregation methods or commonly used universal curves, and prove that new approaches are required. Our work demonstrates new capabilities for the determination of fundamental material properties for a range of structures previously inaccessible to established theoretical models, and at energy levels inaccessible to most experimental techniques

Electrochemistry - variety from volts

Energy Technology Data Exchange (ETDEWEB)

Spurgeon, D.

1985-07-01

At a UNESCO conference held in Paris, France in June 1984 to honor Alessandro Volta, many experts maintained that electrochemistry holds much promise for the developing countries because many of its processes are inexpensive, simple, and easily adapted to the materials and conditions of the developing world. Some of the uses of electrochemistry highlighted at the conference, already available or imminent include: semiconductors in photoelectrochemical cells; photoelectrochemical systems for carrying out chemical reaction; electrophoretic deposition of paints or plastic coatings; electrochemical machining; quantitative analysis of chemicals, and diagnostics of brain chemistry.

From zinc selenate to zinc selenide nano structures synthesized by reduction process

International Nuclear Information System (INIS)

Hutagalung, S.D.; Eng, S.T.; Ahmad, Z.A.; Ishak Mat; Yussof Wahab

2009-01-01

One-dimensional nano structure materials are very attractive because of their electronic and optical properties depending on their size. It is well known that properties of material can be tuned by reducing size to nano scale because at the small sizes, that they behave differently with its bulk materials and the band gap will control by the size. The tunability of the band gap makes nano structured materials useful for many applications. As one of the wide band gaps semiconductor compounds, zinc selenide (ZnSe) nano structures (nanoparticles, nano wires, nano rods) have received much attention for the application in optoelectronic devices, such as blue laser diode, light emitting diodes, solar cells and IR optical windows. In this study, ZnSe nano structures have been synthesized by reduction process of zinc selenate using hydrazine hydrate (N 2 H 4 .2H 2 O). The reductive agent of hydrazine hydrate was added to the starting materials of zinc selenate were heat treated at 500 degree Celsius for 1 hour under argon flow to form one-dimensional nano structures. The SEM and TEM images show the formation of nano composite-like structure, which some small nano bar and nano pellets stick to the rod. The x-ray diffraction and elemental composition analysis confirm the formation of mixture zinc oxide and zinc selenide phases. (author)

A facile way to control phase of tin selenide flakes by chemical vapor deposition

Science.gov (United States)

Wang, Zhigang; Pang, Fei

2018-06-01

Although two-dimensional (2D) tin selenides are attracting intense attentions, studies on its phase transition are still relatively few. Here we report a facile way to control the phase growth of tin selenide flakes on mica and SiO2/Si by only adjusting nominal Sn:Se ratio, which refers to the amount of loaded SnO2 and Se precursors. High normal Sn:Se ratio induced SnSe flakes, conversely SnSe2 flakes formed. It could be used as a practical guide to selectively synthesize pure phase of single crystalline 2D layered chalcogenide materials similar to tin selenides.

Chemical Potential Tuning and Enhancement of Thermoelectric Properties in Indium Selenides

Directory of Open Access Journals (Sweden)

Jong-Soo Rhyee

2015-03-01

Full Text Available Researchers have long been searching for the materials to enhance thermoelectric performance in terms of nano scale approach in order to realize phonon-glass-electron-crystal and quantum confinement effects. Peierls distortion can be a pathway to enhance thermoelectric figure-of-merit ZT by employing natural nano-wire-like electronic and thermal transport. The phonon-softening known as Kohn anomaly, and Peierls lattice distortion decrease phonon energy and increase phonon scattering, respectively, and, as a result, they lower thermal conductivity. The quasi-one-dimensional electrical transport from anisotropic band structure ensures high Seebeck coefficient in Indium Selenide. The routes for high ZT materials development of In4Se3−δ are discussed from quasi-one-dimensional property and electronic band structure calculation to materials synthesis, crystal growth, and their thermoelectric properties investigations. The thermoelectric properties of In4Se3−δ can be enhanced by electron doping, as suggested from the Boltzmann transport calculation. Regarding the enhancement of chemical potential, the chlorine doped In4Se3−δCl0.03 compound exhibits high ZT over a wide temperature range and shows state-of-the-art thermoelectric performance of ZT = 1.53 at 450 °C as an n-type material. It was proven that multiple elements doping can enhance chemical potential further. Here, we discuss the recent progress on the enhancement of thermoelectric properties in Indium Selenides by increasing chemical potential.

Synthetic diamond in electrochemistry

International Nuclear Information System (INIS)

Pleskov, Yurii V

1999-01-01

The results of studies on the electrochemistry of diamond carried out during the last decade are reviewed. Methods for the preparation, the crystalline structure and the main electrophysical properties of diamond thin films are considered. Depending on the doping conditions, the diamond behaves as a superwide-gap semiconductor or as a semimetal. It is shown that the 'metal-like' diamond is corrosion-resistant and can be used advantageously as an electrode in the electrosynthesis (in particular, for the electroreduction of compounds that are difficult to reduce) and electroanalysis. Kinetic characteristics of some redox reactions and the impedance parameters for diamond electrodes are presented. The results of comparative studies of the electrodes made of diamond single crystals, polycrystalline diamond and amorphous diamond-like carbon, which reveal the effect of the crystalline structure (e.g., the influence of intercrystallite boundaries) on the electrochemical properties of diamond, are presented. The bibliography includes 99 references.

Selenide Mineralization in the Příbram Uranium and Base-Metal District (Czech Republic

Directory of Open Access Journals (Sweden)

Pavel Škácha

2017-06-01

Full Text Available Selenium mineralization in the Příbram uranium and base-metal district (Central Bohemia, Czech Republic bound to uraninite occurrences in calcite hydrothermal veins is extremely diverse. The selenides antimonselite, athabascaite, bellidoite, berzelianite, brodtkorbite, bukovite, bytízite, cadmoselite, chaméanite, clausthalite, crookesite, dzharkenite, eskebornite, eucairite, ferroselite, giraudite, hakite, klockmannite, naumannite, permingeatite, příbramite, sabatierite, tiemannite, and umangite were found here, including two new mineral phases: Hg-Cu-Sb and Cu-As selenides. Those selenides—and in some cases their sulphidic equivalents—are characterized using wavelength-dispersive spectroscopy, reflected light, powder X-ray diffraction, single crystal X-ray diffraction, Raman spectroscopy, and electron backscatter diffraction. The selenide mineralization in the Příbram uranium district is bound to the border of the carbonate-uraninite and subsequent carbonate-sulphidic stages. Selenides crystallized there at temperatures near 100 °C in the neutral-to-weakly-alkaline environment from solutions with high oxygen fugacity and a high Se2/S2 fugacity ratio.

catena-Poly[[copper(II-bis[μ-bis(3,5-dimethyl-1H-pyrazol-4-yl selenide

Directory of Open Access Journals (Sweden)

Maksym Seredyuk

2009-11-01

Full Text Available In the title compound, {[Cu(C10H14N4Se2](ClO42}n, the CuII ion is located on a twofold rotation axis and has a tetragonally distorted square-planar geometry constituted by four N atoms. A pair of bis(3,5-dimethyl-1H-pyrazol-4-yl selenide (L ligands bridges the copper centers into a polymeric chain extending along [001]. The perchlorate anions are involved in intermolecular N—H...O hydrogen bonding, which links the chains into layers parallel to the bc plane.

Ammonia-free chemical bath method for deposition of microcrystalline cadmium selenide films

International Nuclear Information System (INIS)

Lokhande, C.D.; Lee, Eun-Ho; Jung, Kwang-Deog; Joo, Oh-Shim

2005-01-01

Chemical deposition of cadmium selenide (CdSe) films has been carried out from alkaline aqueous solution containing Cd 2+ and Se 2- ions. In general, the alkaline pH of the CdSe deposition bath has been adjusted by addition of liquid ammonia. However, the use of ammonia in large-scale chemical deposition method represents an environmental problem due to its volatility and toxicity. The volatility of ammonia changes the pH of deposition bath and results into irreproducible film properties. In the present paper, ammonia-free and weak alkaline (pH < 9.0) chemical method for cadmium selenide film has been developed. The cadmium selenide films are microcrystalline (grain size 0.5-0.7 μm) with hexagonal crystal structure. These films are photoactive and therefore, useful in photo conversion of light into electrical power

On some derived compounds of fluorides of Cerium III or IV: defined compounds and non stoichiometric phases

International Nuclear Information System (INIS)

Besse, Jean-Pierre

1968-01-01

This research study addresses the study of rare earth fluorides. It reports the preparation and study of new fluoro-cerates (IV) in order to complete the set of already known compounds (ammonium fluoro-cerate, and alkaline earth compounds), the study of binary CeF 3 binary systems, monovalent and divalent fluorides, and CeF 3 -NF 2 -N'F ternary systems, and the study of non stoichiometric phases in CeF 3 oxides, sulphides and selenides [fr

Mechanochemical synthesis of nanocrystalline lead selenide. Industrial approach

Energy Technology Data Exchange (ETDEWEB)

Achimovicova, Marcela; Balaz, Peter [Slovak Academy of Sciences, Kosice (Slovakia). Inst. of Geotechnics; Durisin, Juraj [Slovak Academy of Sciences, Kosice (Slovakia). Inst. of Materials Research; Daneu, Nina [Josef Stefan Institute, Ljubljana (Slovenia). Dept. for Nanostructured Materials; Kovac, Juraj; Satka, Alexander [Slovak Univ. of Technology and International Laser Centre, Bratislava (Slovakia). Dept. of Microelectronics; Feldhoff, Armin [Leibniz Univ. Hannover (Germany). Inst. fuer Physikalische Chemie und Elektrochemie; Gock, Eberhard [Technical Univ. Clausthal, Clausthal-Zellerfeld (Germany). Inst. of Mineral and Waste Processing and Dumping Technology

2011-04-15

Mechanochemical synthesis of lead selenide PbSe nanoparticles was performed by high-energy milling of lead and selenium powder in a laboratory planetary ball mill and in an industrial eccentric vibratory mill. Structural properties of the synthesized lead selenide were characterized using X-ray diffraction that confirmed crystalline nature of PbSe nanoparticles. The average size of PbSe crystallites of 37 nm was calculated from X-ray diffraction data using the Williamson-Hall method. The methods of particle size distribution analysis, specific surface area measurement, scanning electron microscopy and transmission electron microscopy were used for characterization of surface, mean particle size, and morphology of PbSe. An application of industrial mill verified a possibility of the synthesis of a narrow bandgap semiconductor PbSe at ambient temperature and in a relatively short reaction time. (orig.)

Carbon Nanotube Electrodes for Hot-Wire Electrochemistry

Czech Academy of Sciences Publication Activity Database

Gründler, P.; Frank, Otakar; Kavan, Ladislav; Dunsch, L.

2009-01-01

Roč. 10, č. 3 (2009), s. 559-563 ISSN 1439-4235 R&D Projects: GA AV ČR IAA400400804; GA AV ČR KAN200100801 Institutional research plan: CEZ:AV0Z40400503 Keywords : electrochemistry * electrodes * nanotubes * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 3.453, year: 2009

The Electrochemistry of Organophosphorus Compounds.

Science.gov (United States)

1988-01-20

of hydrogen on the electrode surface. Mechanistkc views are further developed with the addition of water resulting in the formation of...the exclusive vlide product. Furthermore, carbonvl compounds were added to the electrolyses to react with the electrochemically-generated ylides via...the Wittig reaction. The resulting olefins were found to catalytically isomerize from the Z isomer to the E isomer upon reduction. The role of water

Protein Electrochemistry: Questions and Answers.

Science.gov (United States)

Fourmond, V; Léger, C

This chapter presents the fundamentals of electrochemistry in the context of protein electrochemistry. We discuss redox proteins and enzymes that are not photoactive. Of course, the principles described herein also apply to photobioelectrochemistry, as discussed in later chapters of this book. Depending on which experiment is considered, electron transfer between proteins and electrodes can be either direct or mediated, and achieved in a variety of configurations: with the protein and/or the mediator free to diffuse in solution, immobilized in a thick, hydrated film, or adsorbed as a sub-monolayer on the electrode. The experiments can be performed with the goal to study the protein or to use it. Here emphasis is on mechanistic studies, which are easier in the configuration where the protein is adsorbed and electron transfer is direct, but we also explain the interpretation of signals obtained when diffusion processes affect the response.This chapter is organized as a series of responses to questions. Questions 1-5 are related to the basics of electrochemistry: what does "potential" or "current" mean, what does an electrochemical set-up look like? Questions 6-9 are related to the distinction between adsorbed and diffusive redox species. The answers to questions 10-13 explain the interpretation of slow and fast scan voltammetry with redox proteins. Questions 14-19 deal with catalytic electrochemistry, when the protein studied is actually an enzyme. Questions 20, 21 and 22 are general.

Fundamentals and applications of electrochemistry

Science.gov (United States)

McEvoy, A. J.

2013-06-01

The Voltaic pile, invented here on Lake Como 200 years ago, was a crucial step in the development of electrical engineering. For the first time a controlled and reliable source of electric current was available. The science of electrochemistry developed rapidly and is now a key contributor, not just to energy technology but also, for example, to metallurgy and industrial processes. The basic concepts of electrochemistry are presented, with the practical examples of its application in fuel cells, and with the perspective of the history of the subject.

Electrochemistry in fast reactor technology

International Nuclear Information System (INIS)

Mathews, C.K.

1987-01-01

Electrochemistry plays a significant role in the production, characterisation or behaviour of the fuel, the coolant and structural materials used in fast reactor systems. The role of electrochemistry in sodium production, in the fuel cycle, in the development of electrochemical meters used for the on-line monitoring of the various impurities at sub ppm levels and in the recovery of plutonium and uranium are discussed. The advantage of voltammmetric techniques in the analysis of impurities and the application of electrochemical meters have been investigated. (author). 5 figs., 15 refs

Cybernetic prediction of selenide Chevreul's phases

International Nuclear Information System (INIS)

Kiseleva, N.N.; Savitskij, E.M.

1981-01-01

The method of training a computer is used to forecast the possibility for the formation of selenide Chevreul's phases of the Asub(x)Bsub(6)Sesub(8) composition (where A is any chemical element, B-Mo, Cr, W, Re). The peculiarities of applying cybernetic forecasting systems in inorganic chemistry are considered. The critical temperature of transfer into the superconducting state of some phases forecasted is estimated [ru

Diagnostic Genesis Features of Au-Ag Selenide-Telluride Mineralization of Western Java Deposits

Directory of Open Access Journals (Sweden)

Euis Tintin Yuningsih

2016-01-01

Full Text Available DOI: 10.17014/ijog.3.1.67-76The ore mineralogy of the westernmost part of West Java such as Pongkor, Cibaliung, Cikidang, Cikotok, and Cirotan are characterized by the dominance of silver-arsenic-antimony sulfosalt with silver selenides and rarely tellurides over the argentite, whereas the eastern part of West Java including Arinem and Cineam deposits are dominated by silver-gold tellurides. Mineralogy of Se-type deposits at Pongkor, Cikidang, Cibaliung, Cisungsang, and Cirotan and Te-type deposits at Arinem and Cineam shows their different geochemical characteristics. Mineralogical and geochemical differences can be explained by variation of physico-chemical conditions that existed during gold-silver deposition by applying the phase relation among sulfide, telluride, and selenide mineral association in the deposits. The relative values of ƒSe2(g, ƒTe(g, and ƒS2(g control the actual presence of selenide or telluride minerals within the West Java deposits, which also depend on their concentrations in the hydrothermal fluid. Even though the concentration of selenium in the hydrothermal fluid of Te-type deposits might have been similar or even higher than that in the Se-type, early substitution of selenium in the sulfide minerals prevents its concentration in the hydrothermal fluid to the levels for precipitating selenide minerals. Therefore, early sulfide mineral deposition from reduction fluids will not increase the ƒSe2(g/ƒS2(g ratio to form selenide minerals in Te-type deposits of Arinem and Cineam, other than selenium-bearing sulfide mineral such as Se-bearing galena or Se-bearing pyrargyrite-proustite.

catena-Poly[[copper(II)-bis[μ-bis(3,5-dimethyl-1H-pyrazol-4-yl) selenide

Science.gov (United States)

Seredyuk, Maksym; Haukka, Matti; Pavlenko, Vadim A.; Fritsky, Igor O.

2009-01-01

In the title compound, {[Cu(C10H14N4Se)2](ClO4)2}n, the CuII ion is located on a twofold rotation axis and has a tetra­gonally distorted square-planar geometry constituted by four N atoms. A pair of bis(3,5-dimethyl-1H-pyrazol-4-yl) selenide (L) ligands bridges the copper centers into a polymeric chain extending along [001]. The perchlorate anions are involved in inter­molecular N—H⋯O hydrogen bonding, which links the chains into layers parallel to the bc plane. PMID:21578140

Application and Utilization of Electrochemistry in Organic Chemistry

Czech Academy of Sciences Publication Activity Database

Navrátil, Tomáš

2011-01-01

Roč. 15, č. 17 (2011), s. 2921-2922 ISSN 1385-2728 R&D Projects: GA AV ČR IAA400400806 Institutional research plan: CEZ:AV0Z40400503 Keywords : electrochemistry * organic chemistry * applications Subject RIV: CG - Electrochemistry Impact factor: 3.064, year: 2011

Versatile cell for in-situ spectroelectrochemical and ex-situ nanomorphological characterization of both water soluble and insoluble phthalocyanine compounds

Czech Academy of Sciences Publication Activity Database

Mansfeldová, Věra; Klusáčková, Monika; Tarábková, Hana; Janda, Pavel; Nesměrák, K.

2016-01-01

Roč. 147, č. 8 (2016), s. 1393-1400 ISSN 0026-9247 Institutional support: RVO:61388955 Keywords : organometallic compounds * electrochemistry * cyclic voltammetry Subject RIV: CG - Electrochemistry Impact factor: 1.282, year: 2016

Crystal structure of non-stoichiometric copper selenides studied by neutron scattering and X-ray diffraction

International Nuclear Information System (INIS)

Bikkulova, N.N.; Yagafarova, Z.A.; Asylguzhina, G.N.; Danilkin, S.A.; Fuess, H.; Skomorokhov, A.N.; Yadrovskii, E.L.; Beskrovnyi, A.I.

2003-01-01

Structural characteristics of non-stoichiometric copper selenides were studied by the elastic neutron and X-ray scattering techniques. Rietveld analysis was used to refine the structure of the high-temperature β-phase of the Cu 1.75 Se, Cu 1.78 Se, and Cu 1.83 Se samples. The homogeneity ranges of the cubic phase were determined. The modification of the crystal structure accompanying the β-α phase transition was studied for Cu 1.75 Se and Cu 1.98 Se compounds within the 443-10 K temperature range. It was shown that the phase transition is accompanied by distortions of the fcc lattice and the ordering of copper ions

Phase-Engineered Type-II Multimetal-Selenide Heterostructures toward Low-Power Consumption, Flexible, Transparent, and Wide-Spectrum Photoresponse Photodetectors.

Science.gov (United States)

Chen, Yu-Ze; Wang, Sheng-Wen; Su, Teng-Yu; Lee, Shao-Hsin; Chen, Chia-Wei; Yang, Chen-Hua; Wang, Kuangye; Kuo, Hao-Chung; Chueh, Yu-Lun

2018-05-01

Phase-engineered type-II metal-selenide heterostructures are demonstrated by directly selenizing indium-tin oxide to form multimetal selenides in a single step. The utilization of a plasma system to assist the selenization facilitates a low-temperature process, which results in large-area films with high uniformity. Compared to single-metal-selenide-based photodetectors, the multimetal-selenide photodetectors exhibit obviously improved performance, which can be attributed to the Schottky contact at the interface for tuning the carrier transport, as well as the type-II heterostructure that is beneficial for the separation of the electron-hole pairs. The multimetal-selenide photodetectors exhibit a response to light over a broad spectrum from UV to visible light with a high responsivity of 0.8 A W -1 and an on/off current ratio of up to 10 2 . Interestingly, all-transparent photodetectors are successfully produced in this work. Moreover, the possibility of fabricating devices on flexible substrates is also demonstrated with sustainable performance, high strain tolerance, and high durability during bending tests. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New materials for solid state electrochemistry

International Nuclear Information System (INIS)

Ferloni, P.; Consiglio Nazionale delle Ricerche, Pavia; Magistris, A.; Consiglio Nazionale delle Ricerche, Pavia

1994-01-01

Solid state electrochemistry is an interdisciplinary area, undergoing nowadays a fast development. It is related on the one hand to chemistry, and on the other hand to crystallography, solid state physics and materials science. In this paper structural and electrical properties of some families of new materials interesting for solid state electrochemistry are reviewed. Attention is focused essentially on ceramic and crystalline materials, glasses and polymers, displaying high ionic conductivity and potentially suitable for various applications in solid state electrochemical devices. (orig.)

Electrochemistry-High Resolution Mass Spectrometry to Study Oxidation Products of Trimethoprim

Directory of Open Access Journals (Sweden)

Marc-André Lecours

2018-01-01

Full Text Available The study of the fate of emerging organic contaminants (EOCs, especially the identification of transformation products, after water treatment or in the aquatic environment, is a topic of growing interest. In recent years, electrochemistry coupled to mass spectrometry has attracted a lot of attention as an alternative technique to investigate oxidation metabolites of organic compounds. The present study used different electrochemical approaches, such as cyclic voltammetry, electrolysis, electro-assisted Fenton reaction coupled offline to high resolution mass spectrometry and thin-layer flow cell coupled online to high resolution mass spectrometry, to study oxidation products of the anti-infective trimethoprim, a contaminant of emerging concern frequently reported in wastewaters and surface waters. Results showed that mono- and di-hydroxylated derivatives of trimethoprim were generated in electrochemically and possibly tri-hydroxylated derivatives as well. Those compounds have been previously reported as mammalian and bacterial metabolites as well as transformation products of advance oxidation processes applied to waters containing trimethoprim. Therefore, this study confirmed that electrochemical techniques are relevant not only to mimic specific biotransformation reactions of organic contaminants, as it has been suggested previously, but also to study the oxidation reactions of organic contaminants of interest in water treatment. The key role that redox reactions play in the environment make electrochemistry-high resolution mass spectrometry a sensitive and simple technique to improve our understanding of the fate of organic contaminants in the environment.

Morphology-Tuned Synthesis of Nickel Cobalt Selenides as Highly Efficient Pt-Free Counter Electrode Catalysts for Dye-Sensitized Solar Cells.

Science.gov (United States)

Qian, Xing; Li, Hongmei; Shao, Li; Jiang, Xiancai; Hou, Linxi

2016-11-02

In this work, morphology-tuned ternary nickel cobalt selenides based on different Ni/Co molar ratios have been synthesized via a simple precursor conversion method and used as counter electrode (CE) materials for dye-sensitized solar cells (DSSCs). The experimental facts and mechanism analysis clarified the possible growth process of product. It can be found that the electrochemical performance and structures of ternary nickel cobalt selenides can be optimized by tuning the Ni/Co molar ratio. Benefiting from the unique morphology and tunable composition, among the as-prepared metal selenides, the electrochemical measurements showed that the ternary nickel cobalt selenides exhibited a more superior electrocatalytic activity in comparison with binary Ni and Co selenides. In particular, the three-dimensional dandelion-like Ni 0.33 Co 0.67 Se microspheres delivered much higher power conversion efficiency (9.01%) than that of Pt catalyst (8.30%) under AM 1.5G irradiation.

Electrochemistry and Radioactive Wastes: A Scientific Overview

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Maher Abed Elaziz

2015-12-01

Full Text Available Radioactive wastes are arising from nuclear applications such as nuclear medicine and nuclear power plants. Radioactive wastes should be managed in a safe manner to protect human beings and the environment now and in the future. The management strategy depends on collection, segregation, treatment, immobilization, and disposal. The treatment process is a very important step in which the hazardous materials were converted to a more concentrated, less volume and less movable materials. Electrochemistry is the branch of chemistry in which the passage of electric current was producing a chemical change. Electrochemical treatment of radioactive wastes is widely used all over the world. It has a number of advantages and hence benefits. Electrochemistry can lead to remote, automatic control and increasing safety. The present work is focusing on the role of electrochemistry in the treatment of radioactive wastes worldwide. It contains the fundamentals of electrochemistry, the brief story of radioactive wastes, and the modern trends in the electrochemical treatment of radioactive wastes. An overview of electrochemical decomposition of organic wastes, electrochemical reduction of nitrates, electro- precipitation, electro- ion exchange, and electrochemical remediation of soil are outlined. The main operating factors, the mechanism of decontamination, energy consumption and examples of field trials are considered.

Theory of two-magnon Raman scattering in alkaline iron selenide superconductors

Energy Technology Data Exchange (ETDEWEB)

Liu, C.S. [Department of Physics, Yanshan University, Qinhuangdao 006004 (China); Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China); Zhang, A.M. [Department of Physics, Renmin University of China, Beijing 100872 (China); Xu, T.F. [Department of Physics, Yanshan University, Qinhuangdao 006004 (China); Wu, W.C., E-mail: wu@phy.ntnu.edu.tw [Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China)

2014-11-15

Highlights: • Two-magnon Raman scattering is theoretically studied for alkaline iron selenides. • Underlying spin interactions of the √(5)×√(5) AF superstructure are investigated in details. • Optimal set of exchange parameters is revealed when fitting to experiments. - Abstract: Motivated by the recent experiment of two-magnon Raman scattering in alkaline iron selenide superconductors (Zhang et al., 2012), we investigate in details the underlying spin interactions of the √(5)×√(5) antiferromagnetic superstructure. Based on the linear spin wave approximation, the Fleury-London (FL) two-magnon Raman cross-sections are calculated. By comparing theoretical results with the Raman data in both A{sub g} and B{sub g} channels, an optimal set of exchange parameters which are consistent with the fitting to the neutron scattering data are obtained. It reveals that the experimentally observed broad and asymmetric peaks around 1600 cm{sup −1} are dominantly originated from quasiparticle excitations in two nearly degenerate magnon bands in the (0,±π) and (±π,0) directions. The result thus supports that the magnetic properties in alkaline iron selenide AFe{sub 1.6+x}Se{sub 6} superconductors can be basically described by the quantum spin model with up to third nearest-neighbor exchange couplings.

Exploring the thermoelectric and magnetic properties of uranium selenides: Tl2Ag2USe4 and Tl3Cu4USe6

International Nuclear Information System (INIS)

Azam, Sikander; Khan, Saleem Ayaz; Din, Haleem Ud; Khenata, Rabah; Goumri-Said, Souraya

2016-01-01

The electronic, magnetic and thermoelectric properties of Tl 2 Ag 2 USe 4 and Tl 3 Cu 4 USe 6 compounds were investigated using the full potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The exchange correlation was treated with the generalized gradient approximation plus optimized effective Hubbard parameter and spin–orbit coupling (GGA+U+SOC). The present uranium selenides show narrow direct energy band gap values of 0.7 and 0.875 eV for Tl 2 Ag 2 USe 4 and Tl 3 Cu 4 USe 6 respectively. For both selenides U-d/f states are responsible for electrical transport properties. Uranium atoms were the most contributors in the magnetic moment compared to other atoms and show ferromagnetic nature. The spin density isosurfaces show the polarization of neighboring atoms of Uranium, such as silver/copper and selenium. Thermoelectric calculations reveal that Tl 3 Cu 4 USe 6 is more suitable for thermoelectric device applications than Tl 2 Ag 2 USe 4 . - Highlights: • Electronic, magnetic and thermoelectric properties of uranium selenides are investigated with DFT. • They show a narrow direct energy band gap of 0.7 and 0.875 eV. • U-d/f states are responsible for electrical transport properties. • Tl 3 Cu 4 USe 6 is more suitable for thermoelectric device applications than Tl 2 Ag 2 USe 4 .

Catalysis in electrochemistry: from fundamentals to strategies for fuel cell development

National Research Council Canada - National Science Library

Santos, Elizabeth; Schmickler, Wolfgang

2011-01-01

"Catalysis in Electrochemistry: From Fundamentals to Strategies for Fuel Cell Development is a modern, comprehensive reference work on catalysis in electrochemistry, including principles, methods, strategies, and applications...

Peroxidase-like activity of nanocrystalline cobalt selenide and its application for uric acid detection

Directory of Open Access Journals (Sweden)

Zhuang QQ

2017-04-01

Full Text Available Quan-Quan Zhuang,1 Zhi-Hang Lin,1 Yan-Cheng Jiang,1 Hao-Hua Deng,2 Shao-Bin He,1,3 Li-Ting Su,4 Xiao-Qiong Shi,2 Wei Chen2 1Department of Pharmacy, Affiliated Quanzhou First Hospital of Fujian Medical University, Quanzhou, 2Department of Pharmaceutical Analysis, School of Pharmacy, Fujian Medical University, Fuzhou, 3Department of Pharmacy, Quanzhou Infectious Disease Hospital, 4Department of Pharmaceutical Analysis, Quanzhou Medical College, Quanzhou, People’s Republic of China Abstract: Dendrite-like cobalt selenide nanostructures were synthesized from cobalt and selenium powder precursors by a solvothermal method in anhydrous ethylenediamine. The as-prepared nanocrystalline cobalt selenide was found to possess peroxidase-like activity that could catalyze the reaction of peroxidase substrates in the presence of H2O2. A spectrophotometric method for uric acid (UA determination was developed based on the nanocrystalline cobalt selenide-catalyzed coupling reaction between N-ethyl-N-(3-sulfopropyl-3-methylaniline sodium salt and 4-aminoantipyrine (4-AAP in the presence of H2O2. Under optimum conditions, the absorbance was proportional to the concentration of UA over the range of 2.0–40 µM with a detection limit of 0.5 µM. The applicability of the proposed method has been validated by determination of UA in human serum samples with satisfactory results. Keywords: enzyme mimics, cobalt selenide, peroxidase-like activity, uric acid, human serum

Electrochemistry and Spectroelectrochemistry of Bioactive Hydroxyquinolines: A Mechanistic Study

Czech Academy of Sciences Publication Activity Database

Sokolová, Romana; Nycz, J. E.; Ramešová, Šárka; Fiedler, Jan; Degano, I.; Szala, M.; Kolivoška, Viliam; Gál, M.

2015-01-01

Roč. 119, č. 20 (2015), s. 6074-6080 ISSN 1520-6106 Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR M200401201 Program:M Institutional support: RVO:61388955 Keywords : electrochemistry * spectroelectrochemistry * Bioactive Hydroxyquinolines Subject RIV: CG - Electrochemistry Impact factor: 3.187, year: 2015

Condensed matter physics aspects of electrochemistry

International Nuclear Information System (INIS)

Tosi, M.P.; Kornyshev, A.A.

1991-01-01

This volume collects the proceedings of the Working Party on ''Electrochemistry: Condensed Matter, Atomic and Molecular Physics Aspects'', held for two weeks in the summer of 1990 at the International Centre for Theoretical Physics (ICTP) in Trieste. The goal of the meeting was to discuss those areas of electrochemistry that are accessible to the modern methods of theoretical condensed matter, atomic and molecular physics, in order to stimulate insight and deeper involvement by theoretical physicists into the field. The core of the ICTP Working Party was a set of topically grouped plenary lectures, accompanied by contributed seminars and by the formulation of joint research projects. In the tradition of the ICTP, it was not a meeting of pure theoreticians: about half of the lecturers were professional experimentalists - experts in electrochemistry, physical chemistry, surface science, technical applications. A set of topics was chosen for discussion at the meeting: Liquids, solvation, solutions; The interface (structure, characterization, electric properties, adsorption); Electrodynamics, optics, photo-emission; Charge transfer kinetics (homogeneous and heterogeneous reactions and processes); Superconducting electrodes; Fractal electrodes; Applied research (energy conversion and power sources, electrocatalysis, electroanalysis of turbulent flows). Refs, figs and tabs

Electrochemistry. The basics, with examples

Energy Technology Data Exchange (ETDEWEB)

Lefrou, Christine [LEPMI, Saint Martin d' Heres (France); Poignet, Jean-Claude; Fabry, Pierre

2012-07-01

This book offers original and new approaches to the teaching of electrochemical concepts, principles and applications. Throughout the text the authors provide a balanced coverage of the thermodynamic and kinetic processes at the heart of electrochemical systems. The first half of the book outlines fundamental concepts appropriate to undergraduate students and the second half gives an in-depth account of electrochemical systems suitable for experienced scientists and course lecturers. Concepts are clearly explained and mathematical treatments are kept to a minimum or reported in appendices. This book features: 1. Questions and answers for self-assessment 2. Basic and advanced level numerical descriptions. 3. Illustrated electrochemistry applications This book is accessible to both novice and experienced electrochemists and supports a deep understanding of the fundamental principles and laws of electrochemistry.

Development of an Electrochemistry Teaching Sequence Using a Phenomenographic Approach

Science.gov (United States)

Rodriguez-Velazquez, Sorangel

2013-01-01

Electrochemistry is the area of chemistry that studies electron transfer reactions across an interface. Chemistry education researchers have acknowledged that difficulties in electrochemistry instruction arise due to the level of abstraction of the topic, lack of adequate explanations and representations found in textbooks, and a quantitative…

Synthesis and electrochemistry of tri- and tetranuclear polypyridine derivations of ruthenium

International Nuclear Information System (INIS)

Francis, A.M.A.

1990-01-01

The synthesis of clusters of ruthenium is the focus of this work. The electrochemistry of metal cluster derivatives of ruthenium, iron and osmium are reviewed. The ability of these compounds to undergo more than one electron transfer reaction and to act as electron reservoirs is evident. The synthesis and characterisation of a range of polypyridine derivatives of [Ru 3 (CO) 12 ]; [Ru 3 (CO) 10 (napy)]; [Ru 3 (CO) 10 (bipy)]; [Ru 4 H 4 (CO) 12 ]; [Ru 4 H 4 (CO) 8 (bipy) 2 ] and [Ru 4 H 4 (CO) 10 (bipy)] were dealt with. The crystal structures of [Ru 3 (CO) 10 (napy)] and [Ru 4 H 4 (CO) 10 (bipy)] were also determined. The six compounds were fully investigated and a mechanism for their electrochemical reduction was postulated based on their observed experimental data, and that of the relevant compounds. The techniques used are also described and a brief introduction to the actual theory and practise of these techniques is discussed. 132 refs., 33 figs., 22 tabs

Developments in electrochemistry science inspired by Martin Fleischmann

CERN Document Server

Pletcher, Derek; Williams, David

2014-01-01

Martin Fleischmann was truly one of the 'fathers' of modern electrochemistry having made major contributions to diverse topics within electrochemical science and technology. These include the theory and practice of voltammetry and in situ spectroscopic techniques, instrumentation, electrochemical phase formation, corrosion, electrochemical engineering, electrosynthesis and cold fusion.  While intended to honour the memory of Martin Fleischmann, Developments in Electrochemistry is neither a biography nor a history of his contributions. Rather, the book is a series of critical reviews of topic

Optoelectronic and low temperature thermoelectric studies on nanostructured thin films of silver gallium selenide

Science.gov (United States)

Jacob, Rajani; Philip, Rachel Reena; Nazer, Sheeba; Abraham, Anitha; Nair, Sinitha B.; Pradeep, B.; Urmila, K. S.; Okram, G. S.

2014-01-01

Polycrystalline thin films of silver gallium selenide were deposited on ultrasonically cleaned soda lime glass substrates by multi-source vacuum co-evaporation technique. The structural analysis done by X-ray diffraction ascertained the formation of nano structured tetragonal chalcopyrite thin films. The compound formation was confirmed by X-ray photo-electron spectroscopy. Atomic force microscopic technique has been used for surface morphological analysis. Direct allowed band gap ˜1.78eV with high absorption coefficient ˜106/m was estimated from absorbance spectra. Low temperature thermoelectric effects has been investigated in the temperature range 80-330K which manifested an unusual increase in Seebeck coefficient with negligible phonon drag toward the very low and room temperature regime. The electrical resistivity of these n-type films was assessed to be ˜2.6Ωm and the films showed good photo response.

Zr{sub 2}N{sub 2}Se. The first zirconium(IV) nitride selenide by the oxidation of zirconium(III) nitride with selenium

Energy Technology Data Exchange (ETDEWEB)

Lissner, Falk; Hack, Bettina; Schleid, Thomas [Institute for Inorganic Chemistry, University of Stuttgart (Germany); Lerch, Martin [Institute for Chemistry, Technical University of Berlin (Germany)

2012-08-15

The oxidation of zirconium(III) nitride (ZrN) with suitable amounts of selenium (Se) in the presence of sodium chloride (NaCl) as flux yields small yellow brownish platelets of the first zirconium(IV) nitride selenide with the composition Zr{sub 2}N{sub 2}Se. The new compound crystallizes in the hexagonal space group P6{sub 3}/mmc (no. 194) with a = 363.98(2) pm, c = 1316.41(9) pm (c/a = 3.617) and two formula units per unit cell. The crystallographically unique Zr{sup 4+} cations are surrounded by three selenide and four nitride anions in the shape of a capped trigonal antiprism. The Se{sup 2-} anions are coordinated by six Zr{sup 4+} cations as trigonal prism and the N{sup 3-} anions reside in tetrahedral surrounding of Zr{sup 4+} cations. These [NZr{sub 4}]{sup 13+} tetrahedra become interconnected via three edges each to form {sup 2}{sub ∞}{[(NZr_4_/_4)_2]"2"+} double layers parallel to the (001) plane, which are held together by monolayers of Se{sup 2-} anions. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Coulometric titration at low temperatures-nonstoichiometric silver selenide

OpenAIRE

Beck, Gesa K.; Janek, Jürgen

2003-01-01

A modified coulometric titration technique is described for the investigation of nonstoichiometric phases at low temperatures. It allows to obtain titration curves at temperatures where the conventional coulometric titration technique fails because of too small chemical diffusion coefficients of the mobile component. This method for indirect coulometric titration is applied to silver selenide between -100 and 100 °C. The titration curves are analyzed on the basis of a defect chemical model an...

Aspects of a Distinct Cytotoxicity of Selenium Salts and Organic Selenides in Living Cells with Possible Implications for Drug Design

Directory of Open Access Journals (Sweden)

Ethiene Castellucci Estevam

2015-07-01

Full Text Available Selenium is traditionally considered as an antioxidant element and selenium compounds are often discussed in the context of chemoprevention and therapy. Recent studies, however, have revealed a rather more colorful and diverse biological action of selenium-based compounds, including the modulation of the intracellular redox homeostasis and an often selective interference with regulatory cellular pathways. Our basic activity and mode of action studies with simple selenium and tellurium salts in different strains of Staphylococcus aureus (MRSA and Saccharomyces cerevisiae indicate that such compounds are sometimes not particularly toxic on their own, yet enhance the antibacterial potential of known antibiotics, possibly via the bioreductive formation of insoluble elemental deposits. Whilst the selenium and tellurium compounds tested do not necessarily act via the generation of Reactive Oxygen Species (ROS, they seem to interfere with various cellular pathways, including a possible inhibition of the proteasome and hindrance of DNA repair. Here, organic selenides are considerably more active compared to simple salts. The interference of selenium (and tellurium compounds with multiple targets could provide new avenues for the development of effective antibiotic and anticancer agents which may go well beyond the traditional notion of selenium as a simple antioxidant.

An Effective Approach to Teaching Electrochemistry.

Science.gov (United States)

Birss, Viola I.; Truax, D. Rodney

1990-01-01

An approach which may be useful for teaching electrochemistry in freshman college chemistry courses is presented. Discussed are the potential problems with teaching this subject and solutions provided by this approach. (CW)

The birth of protein electrochemistry.

Science.gov (United States)

Blanford, Christopher F

2013-12-11

The results from a final-year undergraduate project led to an $876M sale of a spin-out company 19 years later: the 1977 communication from Mark Eddowes and Allen Hill seeded the rich field of protein electrochemistry, the technology that underpins commercial glucose biosensors.

Non-haloaluminate room-temperature ionic liquids in electrochemistry--a review.

Science.gov (United States)

Buzzeo, Marisa C; Evans, Russell G; Compton, Richard G

2004-08-20

Some twenty-five years after they first came to prominence as alternative electrochemical solvents, room temperature ionic liquids (RTILs) are currently being employed across an increasingly wide range of chemical fields. This review examines the current state of ionic liquid-based electrochemistry, with particular focus on the work of the last decade. Being composed entirely of ions and possesing wide electrochemical windows (often in excess of 5 volts), it is not difficult to see why these compounds are seen by electrochemists as attractive potential solvents. Accordingly, an examination of the pertinent properties of ionic liquids is presented, followed by an assessment of their application to date across the various electrochemical disciplines, concluding with an outlook viewing current problems and directions.

Cationic and Anionic Disorder in CZTSSe Kesterite Compounds: A Chemical Crystallography Study.

Science.gov (United States)

Bais, Pierre; Caldes, Maria Teresa; Paris, Michaël; Guillot-Deudon, Catherine; Fertey, Pierre; Domengès, Bernadette; Lafond, Alain

2017-10-02

The cationic and anionic disorder in the Cu 2 ZnSnSe 4 -Cu 2 ZnSnS 4 (CZTSe-CZTS) system has been investigated through a chemical crystallography approach including X-ray diffraction (in conventional and resonant setup), 119 Sn and 77 Se NMR spectroscopy, and high-resolution transmission electron microscopy (HRTEM) techniques. Single-crystal XRD analysis demonstrates that the studied compounds behave as a solid solution with the kesterite crystal structure in the whole S/(S + Se) composition range. As previously reported for pure sulfide and pure selenide compounds, the 119 Sn NMR spectroscopy study gives clear evidence that the level of Cu/Zn disorder in mixed S/Se compounds depends on the thermal history of the samples (slow cooled or quenched). This conclusion is also supported by the investigation of the 77 Se NMR spectra. The resonant single-crystal XRD technique shows that regardless of the duration of annealing step below the order-disorder critical temperature the ordering is not a long-range phenomenon. Finally, for the very first time, HREM images of pure selenide and mixed S/Se crystals clearly show that these compounds have different microstructures. Indeed, only the mixed S/Se compound exhibits a mosaic-type contrast which could be the sign of short-range anionic order. Calculated images corroborate that HRTEM contrast is highly dependent on the nature of the anion as well as on the local anionic order.

Development of an Electrochemistry Teaching Sequence using a Phenomenographic Approach

Science.gov (United States)

Rodriguez-Velazquez, Sorangel

Electrochemistry is the area of chemistry that studies electron transfer reactions across an interface. Chemistry education researchers have acknowledged that difficulties in electrochemistry instruction arise due to the level of abstraction of the topic, lack of adequate explanations and representations found in textbooks, and a quantitative emphasis in the application of concepts. Studies have identified conceptions (also referred to as misconceptions, alternative conceptions, etc.) about the electrochemical process that transcends academic and preparation levels (e.g., students and instructors) as well as cultural and educational settings. Furthermore, conceptual understanding of the electrochemical process requires comprehension of concepts usually studied in physics such as electric current, resistance and potential and often neglected in introductory chemistry courses. The lack of understanding of physical concepts leads to students. conceptions with regards to the relation between the concepts of redox reactions and electric circuits. The need for instructional materials to promote conceptual understanding of the electrochemical process motivated the development of the electrochemistry teaching sequence presented in this dissertation. Teaching sequences are educational tools that aim to bridge the gap between student conceptions and the scientific acceptable conceptions that instructors expect students to learn. This teaching sequence explicitly addresses known conceptions in electrochemistry and departs from traditional instruction in electrochemistry to reinforce students. previous knowledge in thermodynamics providing the foundation for the explicit relation of redox reactions and electric circuits during electrochemistry instruction. The scientific foundations of the electrochemical process are explained based on the Gibbs free energy (G) involved rather than on the standard redox potential values (E° ox/red) of redox half-reactions. Representations of

Selenide-Based Electrocatalysts and Scaffolds for Water Oxidation Applications

KAUST Repository

Xia, Chuan; Jiang, Qiu; Zhao, Chao; Hedhili, Mohamed N.; Alshareef, Husam N.

2015-01-01

Selenide-based electrocatalysts and scaffolds on carbon cloth are successfully fabricated and demonstrated for enhanced water oxidation applications. A max­imum current density of 97.5 mA cm−2 at an overpotential of a mere 300 mV and a small Tafel slope of 77 mV dec−1 are achieved, suggesting the potential of these materials to serve as advanced oxygen evolution reaction catalysts.

Selenide-Based Electrocatalysts and Scaffolds for Water Oxidation Applications

KAUST Repository

Xia, Chuan

2015-11-05

Selenide-based electrocatalysts and scaffolds on carbon cloth are successfully fabricated and demonstrated for enhanced water oxidation applications. A max­imum current density of 97.5 mA cm−2 at an overpotential of a mere 300 mV and a small Tafel slope of 77 mV dec−1 are achieved, suggesting the potential of these materials to serve as advanced oxygen evolution reaction catalysts.

Dictionary of electrochemistry. Lexikon Elektrochemie

Energy Technology Data Exchange (ETDEWEB)

Hibbert, D B; James, A M

1987-01-01

Electrochemistry, officially a branch of physical chemistry, is an interdisciplinary field bordering on biology, physics, metallurgy and other fields of engineering. This glossary and dictionary presents information and basic knowledge on recent developments in electrochemistry, i.e. fuel cells, corrosion, energy conversion, electrode kinetics, ion-selective electrodes, and bioelectrochemistry. The user is given a short and precise definition of each term, its importance in different fields of science and, in case of measuring units, a description of the method of measurement. Electrochemical and thermodynamic equations are presented without formal proof, but with an indication of their applications and limitations. Access to relevant information is facilitated by drawings and tables. Bibliographic data are many, and SI units are used throughout the book. A dictionary in the annex makes it easier for the user to find English-language literature. The book may be a useful reference book for biologists, microbiologists, biochemists, chemists, pharmacists, geologists, physicists, technicians, and especially metallurgists.

Optoelectronic and low temperature thermoelectric studies on nanostructured thin films of silver gallium selenide

International Nuclear Information System (INIS)

Jacob, Rajani; Philip, Rachel Reena; Nazer, Sheeba; Abraham, Anitha; Nair, Sinitha B.; Pradeep, B.; Urmila, K. S.; Okram, G. S.

2014-01-01

Polycrystalline thin films of silver gallium selenide were deposited on ultrasonically cleaned soda lime glass substrates by multi-source vacuum co-evaporation technique. The structural analysis done by X-ray diffraction ascertained the formation of nano structured tetragonal chalcopyrite thin films. The compound formation was confirmed by X-ray photo-electron spectroscopy. Atomic force microscopic technique has been used for surface morphological analysis. Direct allowed band gap ∼1.78eV with high absorption coefficient ∼10 6 /m was estimated from absorbance spectra. Low temperature thermoelectric effects has been investigated in the temperature range 80–330K which manifested an unusual increase in Seebeck coefficient with negligible phonon drag toward the very low and room temperature regime. The electrical resistivity of these n-type films was assessed to be ∼2.6Ωm and the films showed good photo response

Electrochemistry of isopolytungstate mixtures

International Nuclear Information System (INIS)

Borzenko, M.I.; Botukhova, G.N.; Tsirlina, G.A.; Petrii, O.A.

2008-01-01

Solutions of isopolytungstates are of interest as the precursors for electrodeposited rechargeable tungsten oxides, and also in relation to hydrogen evolution catalysis. Understanding of isopolytungstate electrochemistry is complicated by numerous pH-dependent equilibria. This paper presents some data of dc polarography and UV absorption spectroscopy for solutions always containing several types of coexisting isopolytungstate species, in order to understand the individual electrochemical reactivity of certain isopolyanions

Hydrothermal synthesis and characterization of sea urchin-like nickel and cobalt selenides nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Liu Xiaohe [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China) and School of Metallurgical Science and Engineering, Central South University, Changsha, Hunan 410083 (China)]. E-mail: liuxh@mail.csu.edu.cn; Zhang Ning [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China); Yi Ran [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China); Qiu Guanzhou [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China); Yan Aiguo [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China); Wu Hongyi [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China); Meng Dapeng [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China); Tang, Motang [School of Metallurgical Science and Engineering, Central South University, Changsha, Hunan 410083 (China)

2007-05-25

Sea urchin-like nanorod-based nickel and cobalt selenides nanocrystals have been selective synthesized via a hydrothermal reduction route in which hydrated nickel chloride and hydrated cobalt chloride were employed to supply Ni and Co source and aqueous hydrazine (N{sub 2}H{sub 4}.H{sub 2}O) was used as reducing agent. The composition, morphology, and structure of final products could be easily controlled by adjusting the molar ratios of reactants and process parameters such as hydrothermal time. The morphology and phase structure of the final products have been investigated by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The probable formation mechanism of the sea urchin-like nanorod-based nickel and cobalt selenides nanocrystals was discussed on the basis of the experimental results.

Electrochemistry and Storage

Science.gov (United States)

Thaller, L. H.

1984-01-01

The term electrochemistry implies the use of devices that convert chemical energy into electrical energy and sometimes vice versa. These devices are usually composed of some number of individual cells that are connected together to form a battery. In the cases where these devices cannot be electrically recharged they are usually referred to as primary batteries, whereas if these batteries can be charged and recharged repeatedly, they are called secondary batteries. The past and present uses of primary and secondary batteries in aerospace applications are discussed.

DNA-Mediated Electrochemistry

Science.gov (United States)

Gorodetsky, Alon A.; Buzzeo, Marisa C.

2009-01-01

The base pair stack of DNA has been demonstrated as a medium for long range charge transport chemistry both in solution and at DNA-modified surfaces. This chemistry is exquisitely sensitive to structural perturbations in the base pair stack as occur with lesions, single base mismatches, and protein binding. We have exploited this sensitivity for the development of reliable electrochemical assays based on DNA charge transport at self-assembled DNA monolayers. Here we discuss the characteristic features, applications, and advantages of DNA-mediated electrochemistry. PMID:18980370

Silver(I), Copper(I) and Copper(II) Complex of the New N,Se-Chelate Ligand 2-Phenylselenomethyl-1H-benzimidazole: Electrochemistry and Structure

Czech Academy of Sciences Publication Activity Database

Leboschka, M.; Sieger, M.; Sarkar, B.; Niemeyer, M.; Schurr, T.; Fiedler, Jan; Záliš, Stanislav; Kaim, W.

2009-01-01

Roč. 635, 6-7 (2009), s. 1001-1007 ISSN 0044-2313 R&D Projects: GA AV ČR KAN100400702; GA MŠk OC 139 Institutional research plan: CEZ:AV0Z40400503 Keywords : copper compounds * solid-state structures * electrochemistry * selenother ligand * silver complex Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.226, year: 2009

Proceedings of the ISEAC international symposium cum workshop on electrochemistry

International Nuclear Information System (INIS)

Aggarwal, Suresh K.; Guin, Saurav K.; Kamat, Jayshree V.; Gupta, Ruma

2011-01-01

This symposium highlights the role of chemistry to find out the solution of some global problems. Among the leading branches of chemistry, the foot prints of electrochemistry can be seen in a variety of fields for both fundamental studies and methodological applications. Electrochemistry and allied science has already exhibited its potential to meet the world's need starting from health and medicine, environment, nanofabrication to alternate energy resources. Articles relevant to INIS are indexed separately

Redox-capacitor to connect electrochemistry to redox-biology.

Science.gov (United States)

Kim, Eunkyoung; Leverage, W Taylor; Liu, Yi; White, Ian M; Bentley, William E; Payne, Gregory F

2014-01-07

It is well-established that redox-reactions are integral to biology for energy harvesting (oxidative phosphorylation), immune defense (oxidative burst) and drug metabolism (phase I reactions), yet there is emerging evidence that redox may play broader roles in biology (e.g., redox signaling). A critical challenge is the need for tools that can probe biologically-relevant redox interactions simply, rapidly and without the need for a comprehensive suite of analytical methods. We propose that electrochemistry may provide such a tool. In this tutorial review, we describe recent studies with a redox-capacitor film that can serve as a bio-electrode interface that can accept, store and donate electrons from mediators commonly used in electrochemistry and also in biology. Specifically, we (i) describe the fabrication of this redox-capacitor from catechols and the polysaccharide chitosan, (ii) discuss the mechanistic basis for electron exchange, (iii) illustrate the properties of this redox-capacitor and its capabilities for promoting redox-communication between biology and electrodes, and (iv) suggest the potential for enlisting signal processing strategies to "extract" redox information. We believe these initial studies indicate broad possibilities for enlisting electrochemistry and signal processing to acquire "systems level" redox information from biology.

Electrochemistry, biosensors and microfluidics: a convergence of fields.

Science.gov (United States)

Rackus, Darius G; Shamsi, Mohtashim H; Wheeler, Aaron R

2015-08-07

Electrochemistry, biosensors and microfluidics are popular research topics that have attracted widespread attention from chemists, biologists, physicists, and engineers. Here, we introduce the basic concepts and recent histories of electrochemistry, biosensors, and microfluidics, and describe how they are combining to form new application-areas, including so-called "point-of-care" systems in which measurements traditionally performed in a laboratory are moved into the field. We propose that this review can serve both as a useful starting-point for researchers who are new to these topics, as well as being a compendium of the current state-of-the art for experts in these evolving areas.

Investigating Nanoscale Electrochemistry with Surface- and Tip-Enhanced Raman Spectroscopy.

Science.gov (United States)

Zaleski, Stephanie; Wilson, Andrew J; Mattei, Michael; Chen, Xu; Goubert, Guillaume; Cardinal, M Fernanda; Willets, Katherine A; Van Duyne, Richard P

2016-09-20

The chemical sensitivity of surface-enhanced Raman spectroscopy (SERS) methodologies allows for the investigation of heterogeneous chemical reactions with high sensitivity. Specifically, SERS methodologies are well-suited to study electron transfer (ET) reactions, which lie at the heart of numerous fundamental processes: electrocatalysis, solar energy conversion, energy storage in batteries, and biological events such as photosynthesis. Heterogeneous ET reactions are commonly monitored by electrochemical methods such as cyclic voltammetry, observing billions of electrochemical events per second. Since the first proof of detecting single molecules by redox cycling, there has been growing interest in examining electrochemistry at the nanoscale and single-molecule levels. Doing so unravels details that would otherwise be obscured by an ensemble experiment. The use of optical spectroscopies, such as SERS, to elucidate nanoscale electrochemical behavior is an attractive alternative to traditional approaches such as scanning electrochemical microscopy (SECM). While techniques such as single-molecule fluorescence or electrogenerated chemiluminescence have been used to optically monitor electrochemical events, SERS methodologies, in particular, have shown great promise for exploring electrochemistry at the nanoscale. SERS is ideally suited to study nanoscale electrochemistry because the Raman-enhancing metallic, nanoscale substrate duly serves as the working electrode material. Moreover, SERS has the ability to directly probe single molecules without redox cycling and can achieve nanoscale spatial resolution in combination with super-resolution or scanning probe microscopies. This Account summarizes the latest progress from the Van Duyne and Willets groups toward understanding nanoelectrochemistry using Raman spectroscopic methodologies. The first half of this Account highlights three techniques that have been recently used to probe few- or single-molecule electrochemical

Water as a Promoter and Catalyst for Dioxygen Electrochemistry in Aqueous and Organic Media

Czech Academy of Sciences Publication Activity Database

Staszak-Jirkovský, J.; Subbaraman, R.; Strmcnik, D.; Harrison, K. L.; Diesendruck, Ch. E.; Assary, R.; Frank, Otakar; Kobr, L.; Wiberg, G. K. H.; Genorio, B.; Connell, J. G.; Lopes, P. P.; Stamenkovic, V. R.; Curtiss, L.; Moore, J. S.; Zavadil, K. R.; Markovic, N. M.

2015-01-01

Roč. 5, č. 11 (2015), s. 6600-6607 ISSN 2155-5435 Institutional support: RVO:61388955 Keywords : electrochemistry * electrocatalysis * binding energy Subject RIV: CG - Electrochemistry Impact factor: 9.307, year: 2015

Electrochemistry of conjugated planar anticancer molecules: Irinotecan and Sunitinib

International Nuclear Information System (INIS)

Zotti, Gianni; Berlin, Anna; Vercelli, Barbara

2017-01-01

The evaluation of drug levels is important for personalized therapeutic approaches particularly in cancer care. To this end electrochemistry provides simplicity, low cost, high sensitivity and possibility of miniaturization. Here we report the electrochemistry and UV-visible spectroscopy of two extensively used planar conjugated anticancer molecules, Irinotecan (ITC) and Sunitinib (SUN), in aprotic medium and water. Comparison is made with model compounds without amine ends. The electronic spectra of ITC and SUN in dimethylsulfoxide show similar vibronic patterns (0.2 eV vibrational energy for both) with energy gaps of 3.1 and 2.5 eV respectively. Cyclic voltammetry in acetonitrile shows the same one-electron reduction peak (-1.9 V vs Ag/Ag + ) and oxidation peaks at 1.45 and 0.65 V, both beyond the oxidation of the amine ends (0.45 V). In water the optical energy gaps are unchanged but the vibronic structure is almost lost and the oxidation processes are eased by 0.45 V for SUN and 1.10 V for ITC. The number of oxidatively exchanged electrons in water is two for ITC but four in two subsequent two-electron steps for SUN. The overall oxidation process for ITC likely involves the nucleophilic attack of a water molecule to the quinoline moiety. The first two-electron oxidation of SUN, involving the pyrrole moiety, leads possibly to the conjugated imine ring which is further oxidized to the N-oxide form. Lowering of the electron-transfer activation energy by water is assigned in part to release of molecular rigidity but in ITC the major role is assigned to a nucleophilic attack of water already in the activated state.

Individuals achieve more accurate results with meters that are codeless and employ dynamic electrochemistry.

Science.gov (United States)

Rao, Anoop; Wiley, Meg; Iyengar, Sridhar; Nadeau, Dan; Carnevale, Julie

2010-01-01

Studies have shown that controlling blood glucose can reduce the onset and progression of the long-term microvascular and neuropathic complications associated with the chronic course of diabetes mellitus. Improved glycemic control can be achieved by frequent testing combined with changes in medication, exercise, and diet. Technological advancements have enabled improvements in analytical accuracy of meters, and this paper explores two such parameters to which that accuracy can be attributed. Four blood glucose monitoring systems (with or without dynamic electrochemistry algorithms, codeless or requiring coding prior to testing) were evaluated and compared with respect to their accuracy. Altogether, 108 blood glucose values were obtained for each system from 54 study participants and compared with the reference values. The analysis depicted in the International Organization for Standardization table format indicates that the devices with dynamic electrochemistry and the codeless feature had the highest proportion of acceptable results overall (System A, 101/103). Results were significant when compared at the 10% bias level with meters that were codeless and utilized static electrochemistry (p = .017) or systems that had static electrochemistry but needed coding (p = .008). Analytical performance of these blood glucose meters differed significantly depending on their technologic features. Meters that utilized dynamic electrochemistry and did not require coding were more accurate than meters that used static electrochemistry or required coding. 2010 Diabetes Technology Society.

INTERNALIZING ISLAMIC VALUES IN ELECTROCHEMISTRY LEARNING

Directory of Open Access Journals (Sweden)

Cucu Zenab Subarkah

2016-06-01

Full Text Available The purpose of this paper is to describe a potential way of integrating the knowledge of electrochemistry with a story in the Al-Quran particularly in the sura of Al-Kahfi, verse 83-96. The story tells about an implicit understanding of the concept of electro chemistry. Having the story in the learning of electrochemistry is aimed to internalizing the spirit of Islam in the learning of electro chemistry. Using a classroom action research, this study involved 95 students who are taking the course of Basic Chemistry 2. This study used three instruments, namely: observation sheet of students activity, observation sheet of students attitute, and self-assessment questionnaire. Based on the data, the study found that students were considerably active in each stage of the learning process with the average of activitiy is 78% (good. With regards to attitude, only aspect of responsibility that was not well appeared while the aspects of religious curiosity, cooperative, and communication relatively presented 

Covalent Dimers of 1,3-Diphenylisobenzofuran for Singlet Fission: Synthesis and Electrochemistry

Czech Academy of Sciences Publication Activity Database

Akdag, Akin; Wahab, Abdul; Beran, Pavel; Rulíšek, Lubomír; Dron, P. I.; Ludvík, Jiří; Michl, Josef

2015-01-01

Roč. 80, č. 1 (2015), s. 80-89 ISSN 0022-3263 R&D Projects: GA ČR GA13-21704S; GA ČR(CZ) GA14-31419S Institutional support: RVO:61388963 ; RVO:61388955 Keywords : singlet fission * reduction potentials * electrochemistry * theoretical calculations Subject RIV: CC - Organic Chemistry; CG - Electrochemistry (UFCH-W) Impact factor: 4.785, year: 2015

Students' understandings of electrochemistry

Science.gov (United States)

O'Grady-Morris, Kathryn

Electrochemistry is considered by students to be a difficult topic in chemistry. This research was a mixed methods study guided by the research question: At the end of a unit of study, what are students' understandings of electrochemistry? The framework of analysis used for the qualitative and quantitative data collected in this study was comprised of three categories: types of knowledge used in problem solving, levels of representation of knowledge in chemistry (macroscopic, symbolic, and particulate), and alternative conceptions. Although individually each of the three categories has been reported in previous studies, the contribution of this study is the inter-relationships among them. Semi-structured, task-based interviews were conducted while students were setting up and operating electrochemical cells in the laboratory, and a two-tiered, multiple-choice diagnostic instrument was designed to identify alternative conceptions that students held at the end of the unit. For familiar problems, those involving routine voltaic cells, students used a working-forwards problem-solving strategy, two or three levels of representation of knowledge during explanations, scored higher on both procedural and conceptual knowledge questions in the diagnostic instrument, and held fewer alternative conceptions related to the operation of these cells. For less familiar problems, those involving non-routine voltaic cells and electrolytic cells, students approached problem-solving with procedural knowledge, used only one level of representation of knowledge when explaining the operation of these cells, scored higher on procedural knowledge than conceptual knowledge questions in the diagnostic instrument, and held a greater number of alternative conceptions. Decision routines that involved memorized formulas and procedures were used to solve both quantitative and qualitative problems and the main source of alternative conceptions in this study was the overgeneralization of theory

Electrochemistry coupled to (LC-)MS for the simulation of oxidative biotransformation reactions of PAHs.

Science.gov (United States)

Wigger, Tina; Seidel, Albrecht; Karst, Uwe

2017-06-01

Electrochemistry coupled to liquid chromatography and mass spectrometry was used for simulating the biological and environmental fate of polycyclic aromatic hydrocarbons (PAHs) as well as for studying the PAH degradation behavior during electrochemical remediation. Pyrene and benzo[a]pyrene were selected as model compounds and oxidized within an electrochemical thin-layer cell equipped with boron-doped diamond electrode. At potentials of 1.2 and 1.6 V vs. Pd/H 2 , quinones were found to be the major oxidation products for both investigated PAHs. These quinones belong to a large group of PAH derivatives referred to as oxygenated PAHs, which have gained increasing attention in recent years due to their high abundance in the environment and their significant toxicity. Separation of oxidation products allowed the identification of two pyrene quinone and three benzo[a]pyrene quinone isomers, all of which are known to be formed via photooxidation and during mammalian metabolism. The good correlation between electrochemically generated PAH quinones and those formed in natural processes was also confirmed by UV irradiation experiments and microsomal incubations. At potentials higher than 2.0 V, further degradation of the initial oxidation products was observed which highlights the capability of electrochemistry to be used as remediation technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dinuclear ruthenium sawhorse-type complexes containing carboxylato bridges and ferrocenyl substituents: Synthesis and electrochemistry

Czech Academy of Sciences Publication Activity Database

Auzias, M.; Süss-Fink, G.; Štěpnička, P.; Ludvík, Jiří

2007-01-01

Roč. 360, č. 6 (2007), s. 2023-2028 ISSN 0020-1693 Institutional research plan: CEZ:AV0Z40400503 Keywords : carboxylato bridges * dinuclear complexes * ruthenium * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 1.713, year: 2007

Exploring the thermoelectric and magnetic properties of uranium selenides: Tl{sub 2}Ag{sub 2}USe{sub 4} and Tl{sub 3}Cu{sub 4}USe{sub 6}

Energy Technology Data Exchange (ETDEWEB)

Azam, Sikander; Khan, Saleem Ayaz [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 30614 Pilsen (Czech Republic); Din, Haleem Ud [Department of Physics, Hazara University, Mansehra (Pakistan); Khenata, Rabah [Laboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Département de Technologie, Université de Mascara, Mascara 29000 (Algeria); Goumri-Said, Souraya, E-mail: sosaid@alfaisal.edu [College of Science, Physics department, Alfaisal University, P.O. Box 50927, Riyadh 11533 (Saudi Arabia)

2016-09-01

The electronic, magnetic and thermoelectric properties of Tl{sub 2}Ag{sub 2}USe{sub 4} and Tl{sub 3}Cu{sub 4}USe{sub 6} compounds were investigated using the full potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The exchange correlation was treated with the generalized gradient approximation plus optimized effective Hubbard parameter and spin–orbit coupling (GGA+U+SOC). The present uranium selenides show narrow direct energy band gap values of 0.7 and 0.875 eV for Tl{sub 2}Ag{sub 2}USe{sub 4} and Tl{sub 3}Cu{sub 4}USe{sub 6} respectively. For both selenides U-d/f states are responsible for electrical transport properties. Uranium atoms were the most contributors in the magnetic moment compared to other atoms and show ferromagnetic nature. The spin density isosurfaces show the polarization of neighboring atoms of Uranium, such as silver/copper and selenium. Thermoelectric calculations reveal that Tl{sub 3}Cu{sub 4}USe{sub 6} is more suitable for thermoelectric device applications than Tl{sub 2}Ag{sub 2}USe{sub 4}. - Highlights: • Electronic, magnetic and thermoelectric properties of uranium selenides are investigated with DFT. • They show a narrow direct energy band gap of 0.7 and 0.875 eV. • U-d/f states are responsible for electrical transport properties. • Tl{sub 3}Cu{sub 4}USe{sub 6} is more suitable for thermoelectric device applications than Tl{sub 2}Ag{sub 2}USe{sub 4}.

Electrochemistry and energy science

International Nuclear Information System (INIS)

Vijh, A.K.

1980-01-01

The purpose of the paper is to delineate the structure of moder electrochemistry and to elucidate the manner in which electrochemical ideas and techniques contribute to the development of power sources and the the advancement of energy science. One example of such an application is the prevention of corrosion in the coolant circuit of a nuclear power station, or its decontamination; another is the use of electrolysis for final upgrading of heavy water. (N.D.H.)

Extinction in an extended-face crystal of zinc selenide

International Nuclear Information System (INIS)

Stevenson, A.W.; Barnea, Z.

1982-01-01

X-ray intensity measurements from an extended-face single crystal of cubic zinc selenide obtained by McIntyre, Moss and Barnea (1980) have been re-analysed with a view to explaining the unresolved discrepancies between theory and experiment present in the original analysis of the most severely extinguished reflections. The results are shown to complement the recent findings of a wavelength dependent study using the same crystal specimen and foreshadow the need to allow for the presence of the Borrmann effect

Size effects in electrochemistry

International Nuclear Information System (INIS)

Petrii, Oleg A; Tsirlina, Galina A

2001-01-01

General characteristics of size-dependent phenomena in electrochemical systems are given. Primary attention is paid to methodical achievements of nanoelectrochemistry, which is a line of research created over the last 15 years. The development of the main concepts of electrochemistry initiated by the stream of nanoscopic information is considered. The prospects for local studies of processes on charged interfaces, elementary steps of these processes and application of nanoelectrodes and related systems in interdisciplinary fields are discussed. The bibliography includes 198 references.

Applied Electrochemistry of Aluminum

DEFF Research Database (Denmark)

Li, Qingfeng; Qiu, Zhuxian

Electrochemistry of aluminum is of special importance from both theoretical and technological point of view. It covers a wide range of electrolyte systems from molten fluoride melts at around 1000oC to room temperature molten salts, from aqueous to various organic media and from liquid to solid...... electrolytes. The book is an updated review of the technological advances in the fields of electrolytic production and refining of metals, electroplating, anodizing and other electrochemical surface treatments, primary and secondary batteries, electrolytic capacitors; corrosion and protection and others....

Nanomaterials based on carbon and Ti(IV) oxides: some aspects of their electrochemistry

Czech Academy of Sciences Publication Activity Database

Kavan, Ladislav

2012-01-01

Roč. 9, 8/9 (2012), s. 652-679 ISSN 1475-7435 R&D Projects: GA MŠk LC510; GA AV ČR IAA400400804; GA AV ČR KAN200100801 Institutional research plan: CEZ:AV0Z40400503 Keywords : carbon nanostructures * titanium oxide * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 1.087, year: 2012

A simple and effective approach to the synthesis of alkynyl selenides from terminal alkynes

Institute of Scientific and Technical Information of China (English)

Barahman Movassagh; Mozhgan Navidi

2012-01-01

Alkynyl selenides were prepared under very mild conditions by reacting terminal alkynes with respective diorganic diselenides in the presence of potassium t-butoxide.The advantages of this protocol include the use of readily available substrates and reagent and good yield of the products.

Bipolar electrochemistry.

Science.gov (United States)

Fosdick, Stephen E; Knust, Kyle N; Scida, Karen; Crooks, Richard M

2013-09-27

A bipolar electrode (BPE) is an electrically conductive material that promotes electrochemical reactions at its extremities (poles) even in the absence of a direct ohmic contact. More specifically, when sufficient voltage is applied to an electrolyte solution in which a BPE is immersed, the potential difference between the BPE and the solution drives oxidation and reduction reactions. Because no direct electrical connection is required to activate redox reactions, large arrays of electrodes can be controlled with just a single DC power supply or even a battery. The wireless aspect of BPEs also makes it possible to electrosynthesize and screen novel materials for a wide variety of applications. Finally, bipolar electrochemistry enables mobile electrodes, dubbed microswimmers, that are able to move freely in solution. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Introduction to Electrochemistry and the Use of Electrochemistry to Synthesize and Evaluate Catalysts for Water Oxidation and Reduction

Science.gov (United States)

Hendel, Samuel J.; Young, Elizabeth R.

2016-01-01

Electrochemical analysis is an important skill to teach in chemistry curricula because it is a critical tool in current high-impact chemical research. Electrochemistry enables researchers to analyze a variety of systems extending from molecules to materials that encompass research themes ranging from clean energy to substrate activation in…

The importance of V.G. Levich’s research in the development of modern electrochemistry

DEFF Research Database (Denmark)

Ulstrup, J.; Vorotyntsev, M. A.; Davydov, A. D.

2017-01-01

The fundamental scientific areas founded and developed by V.G. Levich and his school, and their importance in contemporary theoretical electrochemistry have been overviewed.......The fundamental scientific areas founded and developed by V.G. Levich and his school, and their importance in contemporary theoretical electrochemistry have been overviewed....

X-Ray diffraction analysis of thermally evaporated copper tin selenide thin films at different annealing temperature

International Nuclear Information System (INIS)

Mohd Amirul Syafiq Mohd Yunos; Zainal Abidin Talib; Wan Mahmood Mat Yunus; Josephine Liew Ying Chyi; Wilfred Sylvester Paulus

2010-01-01

Semiconductor thin films Copper Tin Selenide, Cu 2 SnSe 3 , a potential compound for semiconductor radiation detector or solar cell applications were prepared by thermal evaporation method onto well-cleaned glass substrates. The as-deposited films were annealed in flowing purified nitrogen, N 2 , for 2 hours in the temperature range from 100 to 500 degree Celsius. The structure of as-deposited and annealed films has been studied by X-ray diffraction technique. The semi-quantitative analysis indicated from the Reitveld refinement show that the samples composed of Cu 2 SnSe 3 and SnSe. These studies revealed that the films were structured in mixed phase between cubic space group F-43 m (no. 216) and orthorhombic space group P n m a (no. 62). The crystallite size and lattice strain were determined from Scherrer calculation method. The results show that increasing in annealing temperature resulted in direct increase in crystallite size and decrease in lattice strain. (author)

Electronic band structure and optical properties of antimony selenide under pressure

Energy Technology Data Exchange (ETDEWEB)

Abhijit, B.K.; Jayaraman, Aditya; Molli, Muralikrishna, E-mail: muralikrishnamolli@sssihl.edu.in [Department of Physics, Sri Sathya Sai Institute of Higher Learning, Prasanthinilayam, 515 134 (India)

2016-05-23

In this work we present the optical properties of Antimony Selenide (Sb{sub 2}Se{sub 3}) under ambient conditions and under pressure of 9.2 GPa obtained using first principles calculations. We investigated the electronic band structure using the FP-LAPW method within the sphere of the density functional theory. Optical properties like refractive index, absorption coefficient and optical conductivity are calculated using the WIEN2k code.

Adsorption and gas-chromatographic properties of tungsten selenide

International Nuclear Information System (INIS)

Gavrilova, T.B.; Kiselev, A.V.; Roshchina, T.M.

1988-01-01

Method of gas chromatography was used to investigate the surface properties of a series of tungsten selenide WSe 2 samples as well as to determine the role of geometrical and electronic structure of adsorbate molecules and their orientation with respect to the surface during adsorption on WSe 2 . Thermodynamic characteristics of hydrocarbon C 6 -C 10 adsorption at surface occupation close to the zero one were determined. Correlation of the values of thermodynamic characteristics of saturated and aromatic hydrocarbon adsorption enabled to refer WSe 2 to nonspecific adsorbents. It is noted that the main role during hydrocarbon adsorption on WSe 2 is played by nonpolar basic facets, occupied by selenium atoms

Medicinal electrochemistry: integration of electrochemistry, medicinal chemistry and computational chemistry.

Science.gov (United States)

Almeida, M O; Maltarollo, V G; de Toledo, R A; Shim, H; Santos, M C; Honorio, K M

2014-01-01

Over the last centuries, there were many important discoveries in medicine that were crucial for gaining a better understanding of several physiological processes. Molecular modelling techniques are powerful tools that have been successfully used to analyse and interface medicinal chemistry studies with electrochemical experimental results. This special combination can help to comprehend medicinal chemistry problems, such as predicting biological activity and understanding drug action mechanisms. Electrochemistry has provided better comprehension of biological reactions and, as a result of many technological improvements, the combination of electrochemical techniques and biosensors has become an appealing choice for pharmaceutical and biomedical analyses. Therefore, this review will briefly outline the present scope and future advances related to the integration of electrochemical and medicinal chemistry approaches based on various applications from recent studies.

Compatibility of Pt-3008 with selected components of the selenide isotope generator system

International Nuclear Information System (INIS)

Keiser, J.R.

1979-04-01

The first in a new generation of radioisotopic thermoelectric generators being built by Teledyne Energy Systems and designated the Selenide Isotope Generator has thermoelectric materials that can be degraded by reaction with O 2 , H 2 O, CO, and other gases. Consequently, for at least the first ground demonstration system a protective xenon atmosphere will be maintained over the thermoelectrics. The high-temperature portion of the atmosphere-retaining structure will be fabricated from the alloy Pt-3008 (Pt--30 wt % Rh--8 wt % W), which was developed at Oak Ridge National Laboratory. For this application Pt-3008 must be compatible with the various insulations and thermoelectric materials. A study of the compatibility of Pt-3008 with these materials and showed that Pt-3008 was embrittled after exposure to some of the insulations that were not adequately outgassed and by one of the thermoelectric materials (Cu 2 Se) in some of the isothermal tests. It is believed that Pt-3008 will be compatible with the Selenide Isotope Generator materials when they are well outgassed and under the temperature gradient conditions of the operating system

Electrochemistry of high-tc superconductors

International Nuclear Information System (INIS)

Petrij, O.A.; Tsirlina, G.A.

1993-01-01

The review deals with the problems of formation of a new section in modern electrochemistry related to various electrochemical aspects of high-temperature superconductivity. Specific properties of multicomponent oxides as electrode materials are pointed out. The data of experimental works on the study of degradation of superconducting ceramics, electroanalysis of complex oxide systems, electric deposition of metals and polymer films upon them are described. Special attention is paid to electrochemical approaches to electrosynthesis of films, possessing high-temperature superconductivity

Electrochemistry in supercritical fluids

Science.gov (United States)

Branch, Jack A.; Bartlett, Philip N.

2015-01-01

A wide range of supercritical fluids (SCFs) have been studied as solvents for electrochemistry with carbon dioxide and hydrofluorocarbons (HFCs) being the most extensively studied. Recent advances have shown that it is possible to get well-resolved voltammetry in SCFs by suitable choice of the conditions and the electrolyte. In this review, we discuss the voltammetry obtained in these systems, studies of the double-layer capacitance, work on the electrodeposition of metals into high aspect ratio nanopores and the use of metallocenes as redox probes and standards in both supercritical carbon dioxide–acetonitrile and supercritical HFCs. PMID:26574527

Electrochemistry of single molecules and biomolecules, molecular scale nanostructures, and low-dimensional systems

DEFF Research Database (Denmark)

Nazmutdinov, Renat R.; Zinkicheva, Tamara T.; Zinkicheva, Tamara T.

2018-01-01

Electrochemistry at ultra-small scales, where even the single molecule or biomolecule can be characterized and manipulated, is on the way to a consolidated status. At the same time molecular electrochemistry is expanding into other areas of sophisticated nano- and molecular scale systems includin...... molecular scale metal and semiconductor nanoparticles (NPs) and other nanostructures, e.g. nanotubes, “nanoflowers” etc.. The new structures offer both new electronic properties and highly confined novel charge transfer environments....

Discussion meet on role of electrochemistry in biosensors, nano-materials, fuel cells and ionic liquids

International Nuclear Information System (INIS)

Aggarwal, S.K.; Gopinath, N.; Sharma, M.K.

2006-09-01

Electrochemistry is a challenging as well as fascinating branch of chemistry, which is finding applications in almost all areas of science and technology. This present discussion covers invited talks and contributed papers on electrochemical biomimetic sensing, electrochemical immuno sensing, electrochemistry of nano-particles and electrowinning. Papers relevant to INIS are indexed separately

Depression-like behavior and mechanical allodynia are reduced by bis selenide treatment in mice with chronic constriction injury: a comparison with fluoxetine, amitriptyline, and bupropion.

Science.gov (United States)

Jesse, Cristiano R; Wilhelm, Ethel A; Nogueira, Cristina W

2010-12-01

Neuropathic pain is associated with significant co-morbidities, including depression, which impact considerably on the overall patient experience. Pain co-morbidity symptoms are rarely assessed in animal models of neuropathic pain. Neuropathic pain is characterized by hyperexcitability within nociceptive pathways and remains difficult to treat with standard analgesics. The present study determined the effect of bis selenide and conventional antidepressants (fluoxetine, amitriptyline, and bupropion) on neuropathic pain using mechanical allodynic and on depressive-like behavior. Male mice were subjected to chronic constriction injury (CCI) or sham surgery and were assessed on day 14 after operation. Mice received oral treatment with bis selenide (1-5 mg/kg), fluoxetine, amitriptyline, or bupropion (10-30 mg/kg). The response frequency to mechanical allodynia in mice was measured with von Frey hairs. Mice were evaluated in the forced swimming test (FST) test for depression-like behavior. The CCI procedure produced mechanical allodynia and increased depressive-like behavior in the FST. All of the drugs produced antiallodynic effects in CCI mice and produced antidepressant effects in control mice without altering locomotor activity. In CCI animals, however, only the amitriptyline and bis selenide treatments significantly reduced immobility in the FST. These data demonstrate an important dissociation between the antiallodynic and antidepressant effects in mice when tested in a model of neuropathic pain. Depressive behavior in CCI mice was reversed by bis selenide and amitriptyline but not by the conventional antidepressants fluoxetine and buproprion. Bis selenide was more potent than the other drugs tested for antidepressant-like and antiallodynic effects in mice.

Asymmetric supercapacitors with metal-like ternary selenides and porous graphene electrodes

KAUST Repository

Xia, Chuan

2016-04-14

Asymmetric supercapacitors provide a promising approach to fabricate capacitive energy storage devices with high energy and power densities. In this work, asymmetric supercapacitors with excellent performance have been fabricated using ternary (Ni, Co)0.85Se on carbon fabric as bind-free positive electrode and porous free-standing graphene films as negative electrode. Owing to their metal-like conductivity (~1.67×106 S m−1), significant electrochemical activity, and superhydrophilic nature, our nanostructured ternary nickel cobalt selenides result in a much higher areal capacitance (2.33 F cm−2 at 4 mA cm−2), better rate performance and cycling stability than their binary selenide equivalents, and other ternary oxides and chalcogenides. Those hybrid supercapacitors can afford impressive areal capacitance and stack capacitance of 529.3 mF cm−2 and 6330 mF cm−3 at 1 mA cm−2, respectively. More impressively, our optimized asymmetric device operating at 1.8 V delivers a very high stack energy density of 2.85 mWh cm−3 at a stack power density of 10.76 mW cm−3, as well as 85% capacitance retention after 10,000 continuous charge-discharge cycles. Even at a high stack power density of 1173 mW cm−3, this device still deliveries a stack energy density of 1.19 mWh cm−3, superior to most of the reported supercapacitors.

Annals of the 4. Brazilian Symposium on Electrochemistry and Electroanalytics

International Nuclear Information System (INIS)

1984-01-01

Theoretical and experimental papers on electrochemistry and electroanalysis are presented. The techniques used are: voltametry, polarography, ellipsometry, coulometric titration, luminescence, potentiometry, electrodeposition and photoelectrochemistry. (C.L.B.) [pt

Direct electrochemistry of hemoglobin entrapped in dextran film on ...

Indian Academy of Sciences (India)

Administrator

28. Li et al used single- walled carbon nanotube (SWCNT) and 1-hexyl-3- ... Electrochemistry of dextran/hemoglobin/carbon ionic liquid electrode. 273. 2.4 Procedures ..... used for the construction of H2O2 biosensor. Acknowledgement.

Two-step synthesis of silver selenide semiconductor with a linear magnetoresistance effect

International Nuclear Information System (INIS)

Yang, Fengxia; Xiong, Shuangtao; Liu, Fengxian; Han, Chong; Zhang, Duanming; Xia, Zhengcai

2012-01-01

A two-step synthesis method for polycrystalline β-silver selenide (β-Ag 2 Se) was developed. In the first step, nanopowder was prepared using a chemical conversion method at room temperature. In the second step, the nanopowder was compressed and then the bulk Ag 2 Se was fabricated by the solid-state sintering process. The crystalline phase and morphology were examined. The results showed that β-Ag 2 Se was fast fabricated at room temperature. The dense polycrystalline Ag-rich Ag 2 Se was synthesized successfully at 450 °C for 0.5 h under Argon flow. For the polycrystalline, the electronic properties and transverse magnetoresistance (TMR) in a pulsed magnetic field were investigated. The samples displayed n-type semiconducting behaviors and a critical temperature with a broaden temperature range of 140–150 K. Also, it presented a positive and nearly linear dependence on magnetic field H at H ≥ H c (crossover field) ranging from 2 to 20 T. Moreover, the linear dependence of TMR at strong field was non-saturating up to 35 T. Combining with the observation of morphology, it is thought that this unusual TMR effect was caused by slightly excess Ag. This new synthesis method provided a potential route to synthesize nonstoichiometric silver selenide. (paper)

Analysis of Protein-Phenolic Compound Modifications Using Electrochemistry Coupled to Mass Spectrometry.

Science.gov (United States)

Kallinich, Constanze; Schefer, Simone; Rohn, Sascha

2018-01-29

In the last decade, electrochemical oxidation coupled with mass spectrometry has been successfully used for the analysis of metabolic studies. The application focused in this study was to investigate the redox potential of different phenolic compounds such as the very prominent chlorogenic acid. Further, EC/ESI-MS was used as preparation technique for analyzing adduct formation between electrochemically oxidized phenolic compounds and food proteins, e.g., alpha-lactalbumin or peptides derived from a tryptic digestion. In the first step of this approach, two reactant solutions are combined and mixed: one contains the solution of the digested protein, and the other contains the phenolic compound of interest, which was, prior to the mixing process, electrochemically transformed to several oxidation products using a boron-doped diamond working electrode. As a result, a Michael-type addition led to covalent binding of the activated phenolic compounds to reactive protein/peptide side chains. In a follow-up approach, the reaction mix was further separated chromatographically and finally detected using ESI-HRMS. Compound-specific, electrochemical oxidation of phenolic acids was performed successfully, and various oxidation and reaction products with proteins/peptides were observed. Further optimization of the reaction (conditions) is required, as well as structural elucidation concerning the final adducts, which can be phenolic compound oligomers, but even more interestingly, quite complex mixtures of proteins and oxidation products.

2010 Gordon Research Conference, Electrochemistry, January 9-15, 2010

Energy Technology Data Exchange (ETDEWEB)

Creager, Stephen [Clemson Univ., SC (United States)

2010-12-31

Electrochemical science plays a crucial role in many important technologies and is intimately involved in many natural phenomena. Several new Gordon Research Conferences have appeared recently that are dedicated to electrochemical technologies, however electrochemistry as a discipline continues to thrive and provide the underpinnings of these technologies. The 2010 Electrochemistry GRC will focus on a wide range of fundamental electrochemical phenomena and materials and on their application in areas involving energy storage, information storage, chemical analysis, and motion actuation. The meeting will include sessions dedicated to the following specific topics: electrochemical energy storage (e.g. batteries; at least two sessions); electrochemical motion actuation (e.g. electrokinesis); electrocatalysis; electrochemistry in digital information storage; and bioelectrochemistry (including bioanalysis). An Open Session devoted to highlighting the activities of {approx}10 young investigators and non-North American visitors via brief 10-minute talks, and two open poster sessions highlighting the contributions of approximately 60 conference participants including graduate students, will be held. Altogether the conference is expected to include approximately 90 presentations. As has been the case in the recent past, the meeting will bring together participants from academia, national labs, and the private sector, including senior and junior-level scientists, postdoctoral scientists, and graduate students for informal interactions and exchange of ideas. An affiliated Gordon-Kenan Research Seminar (GRS) will also be held with the conference. Special efforts will be made to invite participation from members of underrepresented groups.

Proceedings of the fifth ISEAC triennial international conference on advances and recent trends in electrochemistry

International Nuclear Information System (INIS)

Aggarwal, Suresh K.; Guin, Saurav K.; Sharma, Manoj K.; Kamat, Jayshree V.; Ambolikar, Arvind S.

2013-01-01

The fifth international conference on advances and recent trends in electrochemistry was held during January 16-20, 2013 at Hyderabad. The topics covered under it were on electrochemistry and different branches of science and technology including nuclear science. Articles on electrochemical quartz crystal microbalance, scanning electrochemical microscope, electrochemical biosensors and ionic liquids are also included. Papers relevant to INIS are indexed separately

Dinuclear hexamethylbenzene ruthenium cations containing eta(1):eta(2)-2-(ferrocenyl)ethen-1-yl ligands: Synthesis, structure, electrochemistry

Czech Academy of Sciences Publication Activity Database

Tschan, M. J.-L.; Therrien, B.; Ludvík, Jiří; Štěpnička, P.; Süss-Fink, G.

2006-01-01

Roč. 691, č. 20 (2006), s. 4304-4311 ISSN 0022-328X Institutional research plan: CEZ:AV0Z40400503 Keywords : arene ligands * electrochemistry * ferrocene derivatives Subject RIV: CG - Electrochemistry Impact factor: 2.332, year: 2006

Electrosynthesis of cadmium selenide films from sodium citrate-selenosulphite bath

International Nuclear Information System (INIS)

Lokhande, C.D.; Lee, Eun-Ho; Jung, Kwang-Deog; Joo, Oh-Shim

2005-01-01

Electrosynthesis of cadmium selenide (CdSe) film has been carried out from deposition bath containing sodium selenosulphite, along with cadmium complexed with sodium citrate under potentiostatic deposition condition on titanium substrates. The pH of deposition bath was weakly basic (< 9.0). The CdSe films up to 3.0 μm were deposited. The X-ray diffraction (XRD) studies revealed that the CdSe films are microcrystalline with increased grain size after annealing. The scanning electron microscopy showed that the films are porous with cauliflower-like morphology. The photelectrochemical characterization showed that the CdSe films are photoactive

go to top Electrochemistry and Spectroscopy of an Energetic Material FOX-7. A molecular Approach to Degradation Mechanism

Czech Academy of Sciences Publication Activity Database

Šimková, Ludmila; Urban, Jiří; Klíma, Jiří; Ludvík, Jiří

2012-01-01

Roč. 4, č. 6 (2012), s. 554-560 ISSN 2035-1755 R&D Projects: GA MŠk ME09002 Institutional support: RVO:61388955 Keywords : 2,2-Dinitroethene-1,1-Diamine * Degradation Mechanism * Electrochemistry Subject RIV: CG - Electrochemistry

Synthesis, spectra and electrochemistry of dinitro-bis- {2-(phenylazo ...

Indian Academy of Sciences (India)

Unknown

2006-09-18

Sep 18, 2006 ... Synthesis, spectra and electrochemistry of dinitro-bis-. {2-(phenylazo)pyrimidine} ruthenium(II). Nitro–nitroso derivatives and reactivity of the electrophilic nitrosyl centre. PRITHWIRAJ BYABARTTA. Department of Chemistry, The University of Burdwan, Burdwan 713 104. Present address: Departmento de ...

Solved problems in electrochemistry

International Nuclear Information System (INIS)

Piron, D.L.

2004-01-01

This book presents calculated solutions to problems in fundamental and applied electrochemistry. It uses industrial data to illustrate scientific concepts and scientific knowledge to solve practical problems. It is subdivided into three parts. The first uses modern basic concepts, the second studies the scientific basis for electrode and electrolyte thermodynamics (including E-pH diagrams and the minimum energy involved in transformations) and the kinetics of rate processes (including the energy lost in heat and in parasite reactions). The third part treats larger problems in electrolysis and power generation, as well as in corrosion and its prevention. Each chapter includes three sections: the presentation of useful principles; some twenty problems with their solutions; and, a set of unsolved problems

Physical, optical and electrical properties of copper selenide (CuSe) thin films deposited by solution growth technique at room temperature

International Nuclear Information System (INIS)

Gosavi, S.R.; Deshpande, N.G.; Gudage, Y.G.; Sharma, Ramphal

2008-01-01

Copper selenide (CuSe) thin films are grown onto amorphous glass substrate from an aqueous alkaline medium using solution growth technique (SGT) at room temperature. The preparative parameters were optimized to obtain good quality of thin films. The as-deposited films were characterized for physical, optical and electrical properties. X-ray diffraction (XRD) pattern reveals that the films are polycrystalline in nature. Energy dispersive analysis by X-ray (EDAX) shows formation of stoichiometric CuSe compound. Uniform deposition of CuSe thin films on glass substrate was observed from scanning electron microscopy (SEM) and atomic force microscopy (AFM) micrographs. Average grain size was determined to 144.53 ± 10 nm using atomic force microscopy. The band gap was found to be 2.03 eV with direct band-to-band transition. Semi-conducting behaviour was observed from resistivity measurements. Ohmic behaviour was seen from I-V curve with good electrical conductivity

Polycrystalline TiO2 Anatase with a Large Proportion of Crystal Facets (001): Lithium Insertion Electrochemistry

Czech Academy of Sciences Publication Activity Database

Bouša, Milan; Lásková, Barbora; Zukalová, Markéta; Procházka, Jan; Chou, A.; Kavan, Ladislav

2010-01-01

Roč. 157, č. 10 (2010), A1108-A1112 ISSN 0013-4651 R&D Projects: GA MŠk LC510; GA AV ČR IAA400400804; GA AV ČR KAN200100801 Institutional research plan: CEZ:AV0Z40400503 Keywords : polycrystalline * TiO2 * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 2.420, year: 2010

Solid-state electrochemistry on the nanometer and atomic scales: the scanning probe microscopy approach

Science.gov (United States)

Strelcov, Evgheni; Yang, Sang Mo; Jesse, Stephen; Balke, Nina; Vasudevan, Rama K.; Kalinin, Sergei V.

2016-01-01

Energy technologies of the 21st century require understanding and precise control over ion transport and electrochemistry at all length scales – from single atoms to macroscopic devices. This short review provides a summary of recent works dedicated to methods of advanced scanning probe microscopy for probing electrochemical transformations in solids at the meso-, nano- and atomic scales. Discussion presents advantages and limitations of several techniques and a wealth of examples highlighting peculiarities of nanoscale electrochemistry. PMID:27146961

A new one-dimensional compound: Synthesis and structure of InNb3(Se2)6

International Nuclear Information System (INIS)

Deng Shuiquan; Zhuang Honghui; Huang Jinshun; Huang Jingling

1993-01-01

The new one-dimensional compound, indium niobium selenide, was synthesized by high-temperature solid-state reactions. The structure is composed of [Nb 3 (Se 2 ) 6 ] ∞ chains running along the c axis with In atoms intercalated between these chains. All the Nb atoms have rectangular antiprismatic coordination environments. All the Se atoms in the structure are in the form of Se 2 dimers with Se-Se distances of 2.325(2) and 2.356(2) A. (orig.)

Polycrystalline thin films of antimony selenide via chemical bath deposition and post deposition treatments

International Nuclear Information System (INIS)

Rodriguez-Lazcano, Y.; Pena, Yolanda; Nair, M.T.S.; Nair, P.K.

2005-01-01

We report a method for obtaining thin films of polycrystalline antimony selenide via chemical bath deposition followed by heating the thin films at 573 K in selenium vapor. The thin films deposited from chemical baths containing one or more soluble complexes of antimony, and selenosulfate initially did not show X-ray diffraction (XRD) patterns corresponding to crystalline antimony selenide. Composition of the films, studied by energy dispersive X-ray analyses indicated selenium deficiency. Heating these films in presence of selenium vapor at 573 K under nitrogen (2000 mTorr) resulted in an enrichment of Se in the films. XRD peaks of such films matched Sb 2 Se 3 . Evaluation of band gap from optical spectra of such films shows absorption due to indirect transition occurring in the range of 1-1.2 eV. The films are photosensitive, with dark conductivity of about 2 x 10 -8 (Ω cm) -1 and photoconductivity, about 10 -6 (Ω cm) -1 under tungsten halogen lamp illumination with intensity of 700 W m -2 . An estimate for the mobility life time product for the film is 4 x 10 -9 cm 2 V -1

Detector and sensor devices: fabrication from lead compounds. January 1975-September 1988 (Citations from the INSPEC: Information Services for the Physics and Engineering Communities data base). Report for January 1975-September 1988

International Nuclear Information System (INIS)

1988-10-01

This bibliography contains citations concerning developments, properties, and production of lead compound materials for use in detector- and sensor-device fabrication. Topics include infrared detectors, lead compound heterojunctions and photodiodes, photovoltaic and pyroelectric detectors, epitaxial growth methods, remote sensing, and night vision. Development and preparation of lead sulfide, selenide, telluride, and thallium-monoxide compounds are discussed. Performance analysis and applications of lead compound detectors and sensors are examined. (This updated bibliography contains 229 citations, 19 of which are new entries to the previous edition.)

Board and card games for studying electrochemistry: Preliminary research and early design

Science.gov (United States)

Kurniawan, Rizmahardian Ashari; Kurniasih, Dedeh; Jukardi

2017-12-01

Games in the chemistry classroom can offer engaging and fun alternative method of learning. However, only a few games in chemistry, especially in electrochemistry subject are available commercially. In this research, we developed board and card games for studying electrochemistry. We surveyed chemistry teacher and students from 10 different senior high schools in Pontianak to decide content and characteristic of the game. We have designed the game that can be played by four students or four group of students, either as a specific instruction in the classroom or as a supplementary learning material. The game was designed to help students understanding the voltaic cell configuration and its voltaic potential.

Binding of Substrate Locks the Electrochemistry of CRY-DASH into DNA Repair.

Science.gov (United States)

Gindt, Yvonne M; Messyasz, Adriana; Jumbo, Pamela I

2015-05-12

VcCry1, a member of the CRY-DASH family, may serve two diverse roles in vivo, including blue-light signaling and repair of UV-damaged DNA. We have discovered that the electrochemistry of the flavin adenine dinucleotide cofactor of VcCry1 is locked to cycle only between the hydroquinone and neutral semiquinone states when UV-damaged DNA is present. Other potential substrates, including undamaged DNA and ATP, have no discernible effect on the electrochemistry, and the kinetics of the reduction is unaffected by damaged DNA. Binding of the damaged DNA substrate determines the role of the protein and prevents the presumed photochemistry required for blue-light signaling.

Advances in molten salt electrochemistry towards future energy systems

International Nuclear Information System (INIS)

Ito, Yasuhiko

2005-01-01

This review article describes some selected novel molten salt electrochemical processes which have been created/developed by the author and his coworkers, with emphasis on the applications towards future energy systems. After showing a perspective of the applications of molten salt electrochemistry from the viewpoints of energy and environment, several selected topics are described in detail, which include nitride fuel cycle in a nuclear field, hydrogen energy system coupled with ammonia economy, thermally regenerative fuel cell systems, novel Si production process for solar cell and novel molten salt electrochemical processes for various energy and environment related functional materials including nitrides, rare earth-transition metal alloys, fine particles obtained by plasma-induced electrolysis, and carbon film. And finally, the author stresses again, the importance and potential of molten salt electrochemistry, and encourages young students, scientists and researchers to march in a procession hand in hand towards a bright future of molten salts. (author)

Bipolar electrochemistry: from materials science to motion and beyond.

Science.gov (United States)

Loget, Gabriel; Zigah, Dodzi; Bouffier, Laurent; Sojic, Neso; Kuhn, Alexander

2013-11-19

Bipolar electrochemistry, a phenomenon which generates an asymmetric reactivity on the surface of conductive objects in a wireless manner, is an important concept for many purposes, from analysis to materials science as well as for the generation of motion. Chemists have known the basic concept for a long time, but it has recently attracted additional attention, especially in the context of micro- and nanoscience. In this Account, we introduce the fundamentals of bipolar electrochemistry and illustrate its recent applications, with a particular focus on the fields of materials science and dynamic systems. Janus particles, named after the Roman god depicted with two faces, are currently in the heart of many original investigations. These objects exhibit different physicochemical properties on two opposite sides. This makes them a unique class of materials, showing interesting features. They have received increasing attention from the materials science community, since they can be used for a large variety of applications, ranging from sensing to photosplitting of water. So far the great majority of methods developed for the generation of Janus particles breaks the symmetry by using interfaces or surfaces. The consequence is often a low time-space yield, which limits their large scale production. In this context, chemists have successfully used bipolar electrodeposition to break the symmetry. This provides a single-step technique for the bulk production of Janus particles with a high control over the deposit structure and morphology, as well as a significantly improved yield. In this context, researchers have used the bipolar electrodeposition of molecular layers, metals, semiconductors, and insulators at one or both reactive poles of bipolar electrodes to generate a wide range of Janus particles with different size, composition and shape. In using bipolar electrochemistry as a driving force for generating motion, its intrinsic asymmetric reactivity is again the

(The latest developments of the physical aspects of electrochemistry)

Energy Technology Data Exchange (ETDEWEB)

Liu, S.H.

1990-09-24

The author was one of 26 invited lecturers to discuss the latest developments of the physical aspects of electrochemistry. He interacted extensively with other lecturers and many participants from developing countries. He also visited with the Director of the Italian Synchrotron Radiation Source now under construction in Trieste, Italy.

Direct electrochemistry of hemoglobin entrapped in dextran film on ...

Indian Academy of Sciences (India)

Direct electrochemistry of hemoglobin (Hb) entrapped in the dextran (De) film on the surface of a room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) modified carbon paste electrode (CILE) has been investigated. UV-Vis and FT-IR spectroscopy showed that Hb retained its native ...

Electrochemistry of V2ON with lithium

International Nuclear Information System (INIS)

Zhou Yongning; Liu Chang; Chen Huajun; Zhang Long; Li Wenjing; Fu Zhengwen

2011-01-01

Highlights: → We have prepared V 2 ON thin film by reactive dc sputtering method and annealing process. → We investigated for its electrochemistry with lithium. → V 2 ON thin films exhibit a large reversible specific capacity of 830 mAh g -1 with much less polarization than VN thin films. → The reversible transformation between nanocrystalline V 2 ON and well dispersed V, Li 2 O, Li 3 N nano-composites were revealed. - Abstract: V 2 ON thin film has been successfully fabricated by reactive dc sputtering method and annealing process and was investigated for its electrochemistry with lithium. The reversible discharge capacities of V 2 ON/Li cells cycled between 0.01 and 4.0 V were found in the range of 803-915 mAh g -1 during the first 50 cycles. By using ex situ scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction and X-ray photoelectron spectroscopy measurements, the reversible transformation between nanocrystalline V 2 ON and well dispersed V, Li 2 O, Li 3 N nano-composites were revealed in the lithium electrochemical reaction. V 2 ON thin film exhibits high reversible capacity and good cycle performance with remarkable lower polarization than VN thin film.

Electrochemistry of Hemin on Single-Crystal Au(111)-electrode Surfaces

DEFF Research Database (Denmark)

Zhang, Ling; Ulstrup, Jens; Zhang, Jingdong

adsorption on well-defined single-crystal Au(111)-electrode surfaces using electrochemistry combined with scanning tunnelling microscopy under electrochemical control. Hemin gives two voltammetric peaks assigned to adsorbed monomers and dimmers (Fig. 1B). In situ STM shows that hemin self...

Electrochemistry of Some New Alkaline Battery Electrodes

Science.gov (United States)

1976-02-01

1NýT;7 ~~ AFAPI 4TR- 75)aI Electrochemistry of Somwý New Alkaline V CI RG, 0OTNME Dr/ David F., ’Pickett, IM Wayue ’,Hisb’q Mr. R ic ha rd A I Mid...adding ZnO to the electi-olyte (saturated) and usi .j the interc:ell conrec;tor d isr:ussed earlier ,itLh el4cc.roploated zinc ag inst. the silver fo

II Colombian Congress of Electrochemistry (CCEQ) and 2nd Symposium on Nanoscience and Nanotechnology (SNN)

International Nuclear Information System (INIS)

2017-01-01

In the present volume of Journal of Physics: Conference Series we publish the proceedings of the “II Colombian Congress of Electrochemistry (CCEQ) and 2nd Symposium on Nanoscience and Nanotechnology (SNN)”, that was held from, October 4-7, 2016, at the Bucarica headquarters of the Universidad Industrial de Santander (UIS), Bucaramanga, Colombia. The proceedings consist of 45 contributions that were presented as plenary talks at the event. The abstracts of all participants’ contributions were published in the Abstract Book with ISBN 978-958-8819-39-6. The website of the symposium is available at http://cceq.uis.edu.co/. The scientific program of the II CCEQ and 2nd SNN consisted of 5 Plenary Lecture, 3 Magisterial Conferences, 2 Keynote, 54 Oral and 78 Poster Presentations and 3 Courses with the participation of undergraduate and graduate students, professors, researchers and entrepreneurs from Colombia, Spain, Mexico, Brazil and Venezuela. Moreover, the II CCEQ and 2nd SNN provided a forum of exchange in the research and innovation that enrich the area of electrochemistry, Nanoscience and Nanotechnology of the materials and the industrial applications. All papers in these Proceedings refer to one from the following topics: New Materials, Thin Film, Surface Physics, Simulation and Diagnosis, Laser and Hybrid Processes, Biomedical Coatings, Preparation/Characterization/Application Nanomaterials, Surface Modification (Ionic Implantation, Ion Nitriding, PVD, CVD), Electrochemistry of Materials (Electrodeposits, Electropolymerization, Nanoelectrochemistry, Semiconductors), Corrosion, Analytical Electrochemistry, Electrochemistry in Mineral Processing and Metals (Extractive Metallurgy), Storage and Conversion Electrochemical Energy and Environmental Electrochemistry and Water Treatment involving Electrochemical Nature Phenomena. The editor hopes that those interested in the area of the science of materials can to enjoy this reading that reflects a wide variety of

Strain Engineering to Modify the Electrochemistry of Energy Storage Electrodes

Science.gov (United States)

Muralidharan, Nitin; Carter, Rachel; Oakes, Landon; Cohn, Adam P.; Pint, Cary L.

2016-01-01

Strain engineering has been a critical aspect of device design in semiconductor manufacturing for the past decade, but remains relatively unexplored for other applications, such as energy storage. Using mechanical strain as an input parameter to modulate electrochemical potentials of metal oxides opens new opportunities intersecting fields of electrochemistry and mechanics. Here we demonstrate that less than 0.1% strain on a Ni-Ti-O based metal-oxide formed on superelastic shape memory NiTi alloys leads to anodic and cathodic peak potential shifts by up to ~30 mV in an electrochemical cell. Moreover, using the superelastic properties of NiTi to enable strain recovery also recovers the electrochemical potential of the metal oxide, providing mechanistic evidence of strain-modified electrochemistry. These results indicate that mechanical energy can be coupled with electrochemical systems to efficiently design and optimize a new class of strain-modulated energy storage materials. PMID:27283872

Mono and dinuclear iridium, rhodium and ruthenium complexes containing chelating carboxylato pyrazine ligands: Synthesis, molecular structure and electrochemistry

Czech Academy of Sciences Publication Activity Database

Govindaswamy, P.; Therrien, B.; Süss-Fink, G.; Štěpnička, P.; Ludvík, Jiří

2007-01-01

Roč. 692, č. 8 (2007), s. 1661-1671 ISSN 0022-328X R&D Projects: GA MŠk LC510; GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40400503 Keywords : dinuclear complexes * iridium * rhodium * ruthenium * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 2.168, year: 2007

The bioinorganic electrochemistry of vanadium-penicillamine complexes

International Nuclear Information System (INIS)

Bagal, U.A.; Riechel, T.L.

1989-01-01

Vanadium (V) has been found to inhibit (Na + , K + )-ATPase in the sodium pump reaction in erythrocytes. Glutathione has been suggested as the reducing agent that reverses the effect by reducing vanadium to the (IV) oxidation state. Penicillamine is being studied as a model for glutathione since both have sulfhydryl groups which are involved in redox and coordination chemistry. The electrochemistry in DMSO of penicillamine, its carboxylic ester, and their VO 2 + complexes are discussed in this paper

Application on electrochemistry measurement of high temperature high pressure condition in PWR nuclear power plants

International Nuclear Information System (INIS)

Li Yuchun; Xiao Zhongliang; Jiang Ya; Yu Xiaowei; Pang Feifei; Deng Fenfang; Gao Fan; Zhou Nianguang

2011-01-01

High temperature high pressure electrochemistry testing system was comprehensively analyzed in this paper, according to actual status for supervision in primary and secondary circuits of PWR nuclear power plants. Three research methods were reviewed and discussed for in-situ monitor system. By combination with ECP realtime measurement it was executed for evaluation and water chemistry optimization in nuclear power plants. It is pointed out that in-situ electrochemistry measurement has great potential application for water chemistry evaluation in PWR nuclear power plants. (authors)

Understanding Electrochemistry Concepts Using the Predict-Observe-Explain Strategy

Science.gov (United States)

Karamustafaoglu, Sevilay; Mamlok-Naaman, Rachel

2015-01-01

The current study deals with freshman students who study at the Department of Science at the Faculty of Education. The aim of the study was to investigate the effect of teaching electrochemistry concepts using Predict-Observe-Explain (POE) strategy. The study was quasi-experimental design using 20 students each in the experimental group (EG) and…

Proceedings of the conference on electrochemistry of carbon allotropes: Graphite, fullerenes and diamond

Energy Technology Data Exchange (ETDEWEB)

Kinoshita, K. [ed.] [Lawrence Berkeley National Lab., CA (United States); Scherson, D. [ed.] [Case Western Reserve Univ., Cleveland, OH (United States)

1998-02-01

This conference provided an opportunity for electrochemists, physicists, materials scientists and engineers to meet and exchange information on different carbon allotropes. The presentations and discussion among the participants provided a forum to develop recommendations on research and development which are relevant to the electrochemistry of carbon allotropes. The following topics which are relevant to the electrochemistry of carbon allotropes were addressed: Graphitized and disordered carbons, as Li-ion intercalation anodes for high-energy-density, high-power-density Li-based secondary batteries; Carbons as substrate materials for catalysis and electrocatalysis; Boron-doped diamond film electrodes; and Electrochemical characterization and electrosynthesis of fullerenes and fullerene-type materials. Abstracts of the presentations are presented.

LIGA-based microsystem manufacturing:the electrochemistry of through-mold depostion and material properties.

Energy Technology Data Exchange (ETDEWEB)

Kelly, James J. (Sandia National Laboratories, Livermore, CA); Goods, Steven Howard (Sandia National Laboratories, Livermore, CA)

2005-06-01

The report presented below is to appear in ''Electrochemistry at the Nanoscale'', Patrik Schmuki, Ed. Springer-Verlag, (ca. 2005). The history of the LIGA process, used for fabricating dimensional precise structures for microsystem applications, is briefly reviewed, as are the basic elements of the technology. The principal focus however, is on the unique aspects of the electrochemistry of LIGA through-mask metal deposition and the generation of the fine and uniform microstructures necessary to ensure proper functionality of LIGA components. We draw from both previously published work by external researchers in the field as well as from published and unpublished studies from within Sandia.

Radiation-induced physical ageing in network arsenic-sulfide/selenide glasses

International Nuclear Information System (INIS)

Shpotyuk, M; Golovchak, R; Kozdras, A; Shpotyuk, O

2010-01-01

Effect of radiation-induced physical ageing is investigated by differential scanning calorimetry method in As x Se 100-x (10 ≤ x ≤ 42) and As x S 100-x (30 ≤ x ≤ 42) glasses. Obtained results are compared with conventional physical ageing at normal conditions. Significant radiation-induced physical ageing is recorded for glassy As x S 100-x within 30 ≤ x x Se 100-x glasses from the same compositional interval do not show any measurable changes in DSC curves after γ-irradiation. Observed difference in radiation-induced physical ageing in arsenic-sulfide/selenide glasses is explained by a greater lifetime of γ-induced excitations within sulfur-based network in comparison with selenium-based one.

Short-range order in amorphous thin films of indium selenides

International Nuclear Information System (INIS)

Zakharov, V.P.; Poltavtsev, Yu.G.; Sheremet, G.P.

1982-01-01

A structure of the short-range order and a character of interatomic interactions in indium selenides Insub(1-x)Sesub(x) with 0.333 <= x <= 0.75, obtained in the form of amorphous films 0.05-0.80 μm thick are studied using electron diffraction method. It is found out that mostly tetrahedrical coordination of nearest neighbours in the vicinity of indium atoms is characteristic for studied amorphous films, and coordination of selenium atoms is different. Amorphous film with x=0.75 posesses a considereably microheterogeneous structure of the short-range order, which is characterized by the presence of microunclusions of amorphous selenium and atoms of indium, octohedrically coordinated by selenium atoms

Construction and direct electrochemistry of orientation controlled laccase electrode.

Science.gov (United States)

Li, Ying; Zhang, Jiwei; Huang, Xirong; Wang, Tianhong

2014-03-28

A laccase has multiple redox centres. Chemisorption of laccases on a gold electrode through a polypeptide tag introduced at the protein surface provides an isotropic orientation of laccases on the Au surface, which allows the orientation dependent study of the direct electrochemistry of laccase. In this paper, using genetic engineering technology, two forms of recombinant laccase which has Cys-6×His tag at the N or C terminus were generated. Via the Au-S linkage, the recombinant laccase was assembled orientationally on gold electrode. A direct electron transfer and a bioelectrocatalytic activity toward oxygen reduction were observed on the two orientation controlled laccase electrodes, but their electrochemical behaviors were found to be quite different. The orientation of laccase on the gold electrode affects both the electron transfer pathway and the electron transfer efficiency of O2 reduction. The present study is helpful not only to the in-depth understanding of the direct electrochemistry of laccase, but also to the development of laccase-based biofuel cells. Copyright © 2014 Elsevier Inc. All rights reserved.

Selenide mineralization in the Příbram uranium and base-metal district (Czech Republic)

Czech Academy of Sciences Publication Activity Database

Škácha, P.; Sejkora, J.; Plášil, Jakub

2017-01-01

Roč. 7, č. 6 (2017), s. 1-56, č. článku 91. ISSN 2075-163X R&D Projects: GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : selenides * chemical composition * crystal structure * wavelength-dispersive spectroscopy * X-ray diffraction * Příbram Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 2.088, year: 2016

Enzymatic Activity Detection via Electrochemistry for Enceladus

Science.gov (United States)

Studemeister, Lucy; Koehne, Jessica; Quinn, Richard

2017-01-01

Electrochemical detection of biological molecules is a pertinent topic and application in many fields such as medicine, environmental spills, and life detection in space. Proteases, a class of molecules of interest in the search for life, catalyze the hydrolysis of peptides. Trypsin, a specific protease, was chosen to investigate an optimized enzyme detection system using electrochemistry. This study aims at providing the ideal functionalization of an electrode that can reliably detect a signal indicative of an enzymatic reaction from an Enceladus sample.

Synthesis, structure, and electrochemistry and magnetic properties of a novel 1D homochiral MnIII(5-Brsalen) coordination polymer with left-handed helical character

Science.gov (United States)

Dong, Dapeng; Yu, Naisen; Zhao, Haiyan; Liu, Dedi; Liu, Jia; Li, Zhenghua; Liu, Dongping

2016-01-01

A novel homochiral manganese (III) Mn(5-Brsalen) coordination polymer with left-handed helical character by spontaneous resolution on crystallization by using Mn(5-Brsalen) and 4,4-bipyridine, [MnIII(5-Brsalen)(4,4-bipy)]·ClO4·CH3OH (1) (4,4-bipy = 4,4-bipyridine) has been synthesized and structurally characterized by X-ray single-crystal diffraction, elemental analysis and infrared spectroscopy. In compound 1, each manganese(III) anion is six-coordinate octahedral being bonded to four atoms of 5-Brsalen ligand in an equatorial plane and two nitrogen atoms from a 4,4-bipyridine ligand in axial positions. The structure of compound 1 can be described a supramolecular 2D-like structure which was formed by the intermolecular π-stacking interactions between the neighboring chains of the aromatic rings of 4,4-bipyridine and 5-Brsalen molecules. UV-vis absorption spectrum, electrochemistry and magnetic properties of the compound 1 have also been studied.

In-situ Liquid Electron Microscopy Setups for Investigation of Nanoscale Electrochemistry

DEFF Research Database (Denmark)

Jensen, Eric; Møller-Nilsen, Rolf Erling Robberstad; Canepa, Silvia

2014-01-01

-situ electrochemistry and has achieved ~10 nm resolution. Such systems are important tools for developing sustainable technology and for understanding nanoscale phenomena. However, both systems suffer from interacting with theelectron beam, which is a high-voltage radiation source, and therefore initial experiments...

Radiation-induced physical ageing in network arsenic-sulfide/selenide glasses

Energy Technology Data Exchange (ETDEWEB)

Shpotyuk, M; Golovchak, R; Kozdras, A; Shpotyuk, O, E-mail: shpotyuk@novas.lviv.ua

2010-11-15

Effect of radiation-induced physical ageing is investigated by differential scanning calorimetry method in As{sub x}Se{sub 100-x} (10 {<=} x {<=} 42) and As{sub x}S{sub 100-x} (30 {<=} x {<=} 42) glasses. Obtained results are compared with conventional physical ageing at normal conditions. Significant radiation-induced physical ageing is recorded for glassy As{sub x}S{sub 100-x} within 30 {<=} x < 40 range, while As{sub x}Se{sub 100-x} glasses from the same compositional interval do not show any measurable changes in DSC curves after {gamma}-irradiation. Observed difference in radiation-induced physical ageing in arsenic-sulfide/selenide glasses is explained by a greater lifetime of {gamma}-induced excitations within sulfur-based network in comparison with selenium-based one.

Selenide isotope generator for the Galileo mission. Reliability program plan

International Nuclear Information System (INIS)

1978-10-01

The reliability program plan for the Selenide Isotope Generator (SIG) program is presented. It delineates the specific tasks that will be accomplished by Teledyne Energy Systems and its suppliers during design, development, fabrication and test of deliverable Radioisotopic Thermoelectric Generators (RTG), Electrical Heated Thermoelectric Generators (ETG) and associated Ground Support Equipment (GSE). The Plan is formulated in general accordance with procedures specified in DOE Reliability Engineering Program Requirements Publication No. SNS-2, dated June 17, 1974. The Reliability Program Plan presented herein defines the total reliability effort without further reference to Government Specifications. The reliability tasks to be accomplished are delineated herein and become the basis for contract compliance to the extent specified in the SIG contract Statement of Work

A review of electrochemistry of relevance to environment-assisted cracking in light water reactors

International Nuclear Information System (INIS)

Turnbull, A.; Psaila-Dombrowski, M.

1992-01-01

The electrochemistry of relevance to environment-assisted cracking in high temperature, low conductivity water is critically reviewed. The review covers corrosion potential and electrochemical polarisation measurements, thermodynamics, and also experimental measurements and mathematical modelling of the electrochemistry in cracks and crevices. There is a lack of critical data in relation to the electrode kinetics of relevant cathodic reduction reactions, namely H + , H 2 O, O 2 , H 2 O 2 and steady-state anodic reaction data are limited. Transient anodic current measurements, associated with initially film-free metal, have been made for a range of conditions but there is uncertainty regarding the role of fluid flow and transport processes on the current decay characteristics. A number of experimental measurements of potential and pH in crevices and cracks have been made but the experiments are difficult to carry out reliably and hence the range of data of relevance to practical conditions is very limited. Recent developments in mathematical modelling have significantly enhanced the qualitative understanding of the processes controlling the local electrochemistry in cracks and crevices but the reliability of the quantitative predictions is limited by the paucity of reliable input data. (Author)

[Novel Approaches in DNA Methylation Studies - MS-HRM Analysis and Electrochemistry].

Science.gov (United States)

Bartošík, M; Ondroušková, E

Cytosine methylation in DNA is an epigenetic mechanism regulating gene expression and plays a vital role in cell differentiation or proliferation. Tumor cells often exhibit aberrant DNA methylation, e.g. hypermethylation of tumor suppressor gene promoters. New methods, capable of determining methylation status of specific DNA sequences, are thus being developed. Among them, MS-HRM (methylation-specific high resolution melting) and electrochemistry offer relatively inexpensive instrumentation, fast assay times and possibility of screening multiple samples/DNA regions simultaneously. MS-HRM is due to its sensitivity and simplicity an interesting alternative to already established techniques, including methylation-specific PCR or bisulfite sequencing. Electrochemistry, when combined with suitable electroactive labels and electrode surfaces, has been applied in several unique strategies for discrimination of cytosines and methylcytosines. Both techniques were successfully tested in analysis of DNA methylation within promoters of important tumor suppressor genes and could thus help in achieving more precise diagnostics and prognostics of cancer. Aberrant methylation of promoters has already been described in hundreds of genes associated with tumorigenesis and could serve as important biomarker if new methods applicable into clinical practice are sufficiently advanced.Key words: DNA methylation - 5-methylcytosine - HRM analysis - melting temperature - DNA duplex - electrochemistry - nucleic acid hybridizationThis work was supported by MEYS - NPS I - LO1413.The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study.The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 6. 5. 2016Accepted: 16. 5. 2016.

The merger of electrochemistry and molecular electronics.

Science.gov (United States)

McCreery, Richard L

2012-02-01

Molecular Electronics has the potential to greatly enhance existing silicon-based microelectronics to realize new functions, higher device density, lower power consumption, and lower cost. Although the investigation of electron transport through single molecules and molecular monolayers in "molecular junctions" is a recent development, many of the relevant concepts and phenomena are derived from electrochemistry, as practiced for the past several decades. The past 10+ years have seen an explosion of research activity directed toward how the structure of molecules affects electron transport in molecular junctions, with the ultimate objective of "rational design" of molecular components with new electronic functions, such as chemical sensing, interactions with light, and low-cost, low-power consumer electronics. In order to achieve these scientifically and commercially important objectives, the factors controlling charge transport in molecules "connected" to conducting contacts must be understood, and methods for massively parallel manufacturing of molecular circuits must be developed. This Personal Account describes the development of reproducible and robust molecular electronic devices, starting with modified electrodes used in electrochemistry and progressing to manufacturable molecular junctions. Although the field faced some early difficulties in reliability and characterization, the pieces are now in place for rapid advances in understanding charge transport at the molecular level. Inherent in the field of Molecular Electronics are many electrochemical concepts, including tunneling, redox exchange, activated electron transfer, and electron coupling between molecules and conducting contacts. Copyright © 2012 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Development of scintillators on the basis of AIIBVI compounds for radiation instruments used in medical and technical applications

Directory of Open Access Journals (Sweden)

Starzhinskiy N. G.

2009-06-01

Full Text Available Physico-technological problems of preparation and main properties of scintillation materials based on zinc selenide and other AIIBVI compounds are considered. Effects have been determined of dopant properties on formation processes of complex lattice defects playing the role of luminescence centers. It is shown that such property features as high light output and very low afterglow level, as well as a unique combination of scintillation and semiconductor properties allow application of these materials in different fields of radiation instrument technologies.

NASA Glenn Research Center Electrochemistry Branch Overview

Science.gov (United States)

Manzo, Michelle A.; Hoberecht, Mark; Reid, Concha

2010-01-01

This presentation covers an overview of NASA Glenn's history and heritage in the development of electrochemical systems for aerospace applications. Current programs related to batteries and fuel cells are addressed. Specific areas of focus are Li-ion batteries and Polymer Electrolyte Membrane Fuel cells systems and their development for future Exploration missions. The presentation covers details of current component development efforts for high energy and ultra high energy Li-ion batteries and non-flow-through fuel cell stack and balance of plant development. Electrochemistry Branch capabilities and facilities are also addressed.

Electroanalytical Evaluation of Nanoparticles by Nano-impact Electrochemistry

Science.gov (United States)

Karimi, Anahita

Applications of engineered nanoparticles in electronics, catalysis, solid oxide fuel cells, medicine and sensing continue to increase. Traditionally, nanoparticle systems are characterized by spectroscopic and microscopic techniques. These methods are cumbersome and expensive, which limit their routine use for screening purposes. Electrochemistry is a powerful, yet underutilized tool, for the detection and classification of nanoparticles. The first part of this dissertation investigates a recently developed electrochemical method -- nanoparticle collision electrochemistry -- for detection and characterization of nanoparticles. Three independent projects have been described to evaluate the use of this technique for characterizing nanoparticle based systems including: conjugation with biomolecules, interaction with environmental contaminants and fundamental investigation of conformational changes of nanoparticle capping ligands. The thesis reports the first use of nano-impact electrochemistry to quantitatively investigate bioconjugation and biomolecular recognition at conductive nanoparticles. Furthermore, we also demonstrate the potential of this method as a single step, reagentless and label-free technique for the ultra-sensitive detection of biomolecular targets. A fundamental study of biorecognition is important for the development of therapeutics and molecular diagnosis probes in the biomedical, biosensing and biotechnology fields. The second project describes the use of this method as a screening tool of particle reactivity. We study the interaction and adsorption of a toxic environmental metalloid (Arsenic) with metal oxide nanoparticles to extract mechanistic, speciation and loading information. We discuss the potential of this approach to complement or replace costly characterization techniques and enable routine study of nanoparticles and their reactivity. In the third project, we use the nano-impact method to study the pH-dependent conformational changes

The digital structural analysis of cadmium selenide crystals by a method of ion beam thinning for high resolution electron microscopy

International Nuclear Information System (INIS)

Kanaya, Koichi; Baba, Norio; Naka, Michiaki; Kitagawa, Yukihisa; Suzuki, Kunio

1986-01-01

A digital processing method using a scanning densitometer system for structural analysis of electron micrographs was successfully applied to a study of cadmium selenide crystals, which were prepared by an argon-ion beam thinning method. Based on Fourier techniques for structural analysis from a computer-generated diffractogram, it was demonstrated that when cadmium selenide crystals were sufficiently thin to display the higher order diffraction spots at a high resolution approaching the atomic level, they constitute an alternative hexagonal lattice of imperfect wurtzite phase from a superposition of individual harmonic images by the enhanced scattering amplitude and corrected phase. From the structural analysis data, a Fourier synthetic lattice image was reconstructed, representing the precise location and three-dimensional arrangement of each of the atoms in the unit cell. Extensively enhanced lattice defect images of dislocations and stacking faults were also derived and shown graphically. (author)

Nanoscale Electrochemistry of sp(2) Carbon Materials: From Graphite and Graphene to Carbon Nanotubes.

Science.gov (United States)

Unwin, Patrick R; Güell, Aleix G; Zhang, Guohui

2016-09-20

Carbon materials have a long history of use as electrodes in electrochemistry, from (bio)electroanalysis to applications in energy technologies, such as batteries and fuel cells. With the advent of new forms of nanocarbon, particularly, carbon nanotubes and graphene, carbon electrode materials have taken on even greater significance for electrochemical studies, both in their own right and as components and supports in an array of functional composites. With the increasing prominence of carbon nanomaterials in electrochemistry comes a need to critically evaluate the experimental framework from which a microscopic understanding of electrochemical processes is best developed. This Account advocates the use of emerging electrochemical imaging techniques and confined electrochemical cell formats that have considerable potential to reveal major new perspectives on the intrinsic electrochemical activity of carbon materials, with unprecedented detail and spatial resolution. These techniques allow particular features on a surface to be targeted and models of structure-activity to be developed and tested on a wide range of length scales and time scales. When high resolution electrochemical imaging data are combined with information from other microscopy and spectroscopy techniques applied to the same area of an electrode surface, in a correlative-electrochemical microscopy approach, highly resolved and unambiguous pictures of electrode activity are revealed that provide new views of the electrochemical properties of carbon materials. With a focus on major sp(2) carbon materials, graphite, graphene, and single walled carbon nanotubes (SWNTs), this Account summarizes recent advances that have changed understanding of interfacial electrochemistry at carbon electrodes including: (i) Unequivocal evidence for the high activity of the basal surface of highly oriented pyrolytic graphite (HOPG), which is at least as active as noble metal electrodes (e.g., platinum) for outer

A Review on Direct Electrochemistry of Catalase for Electrochemical Sensors

Directory of Open Access Journals (Sweden)

Periasamy Arun Prakash

2009-03-01

Full Text Available Catalase (CAT is a heme enzyme with a Fe(III/II prosthetic group at its redox centre. CAT is present in almost all aerobic living organisms, where it catalyzes the disproportionation of H2O2 into oxygen and water without forming free radicals. In order to study this catalytic mechanism in detail, the direct electrochemistry of CAT has been investigated at various modified electrode surfaces with and without nanomaterials. The results show that CAT immobilized on nanomaterial modified electrodes shows excellent catalytic activity, high sensitivity and the lowest detection limit for H2O2 determination. In the presence of nanomaterials, the direct electron transfer between the heme group of the enzyme and the electrode surface improved significantly. Moreover, the immobilized CAT is highly biocompatible and remains extremely stable within the nanomaterial matrices. This review discusses about the versatile approaches carried out in CAT immobilization for direct electrochemistry and electrochemical sensor development aimed as efficient H2O2 determination. The benefits of immobilizing CAT in nanomaterial matrices have also been highlighted.

Electrochemical oxidation of quaternary ammonium electrolytes : Unexpected side reactions in organic electrochemistry

NARCIS (Netherlands)

Nouri Nigjeh, Eslam; de Vries, Marcel; Bruins, Andries P.; Bischoff, Rainer; Permentier, Hjalmar P.

Quaternary ammonium salts are among the most widely used electrolytes in organic electrochemistry, but there is little known about their unwanted side oxidation reactions. We have, therefore, studied the constant potential oxidation products of quaternary ammonium electrolytes using mass

Development of a controlled-distance electrochemistry arrangement to be used in power plant environments

International Nuclear Information System (INIS)

Bojinov, M.; Laitinen, T.; Moilanen, P.; Maekelae, K.; Maekelae, M.; Saario, T.; Sirkiae, P.

2000-07-01

This publication presents the state-of-the-art of the controlled-distance electrochemistry (CDE) arrangement developed at VTT. Due to the possibility to control accurately the distance between two electrodes, the CDE arrangement makes possible electrochemical measurements in poorly-conductive media such as simulated coolants of light water reactor systems. This experimental arrangement has now been developed into a versatile electrochemical tool, which can be used for thin-layer electrochemistry (TLEC), wall-jet ring-disc and contact electric impedance (CEI) as well as contact electric resistance (CER) measurements. This report comprises results from the years 1997-1999 and summarises the different possible TLEC configurations and electrode locations as well as the development of a bellows-driven CDE system. (orig.)

A study on the optics of copper indium gallium (di)selenide (CIGS) solar cells with ultra-thin absorber layers

NARCIS (Netherlands)

Xu, M.; Wachters, A.J.H.; Van Deelen, J.; Mourad, M.C.D.; Buskens, P.J.P.

2014-01-01

We present a systematic study of the effect of variation of the zinc oxide (ZnO) and copper indium gallium (di)selenide (CIGS) layer thickness on the absorption characteristics of CIGS solar cells using a simulation program based on finite element method (FEM). We show that the absorption in the

Electrochemistry and in situ Raman spectroelectrochemistry of low and high quality boron doped diamond layers in aqueous electrolyte solution

Czech Academy of Sciences Publication Activity Database

Vlčková Živcová, Zuzana; Frank, Otakar; Petrák, Václav; Tarábková, Hana; Vacík, Jiří; Nesládek, M.; Kavan, Ladislav

2013-01-01

Roč. 87, JAN 2013 (2013), s. 518-525 ISSN 0013-4686 R&D Projects: GA AV ČR IAA400400804; GA AV ČR KAN200100801 Grant - others:European Commission CORDIS(XE) FP7-ENERGY-2010-FET, projekt 256617 Institutional support: RVO:61389005 ; RVO:61388955 ; RVO:68378271 Keywords : boron doped diamond * electrochemistry * aqueous electrolyte solution Subject RIV: CG - Electrochemistry Impact factor: 4.086, year: 2013

Proceedings of the eleventh ISEAC international discussion meet on electrochemistry and its applications

International Nuclear Information System (INIS)

Aggarwal, Suresh K.; Guin, Saurav K.; Gupta, Ruma S.; Ambolikar, Arvind S.

2014-01-01

Electrochemistry has truly emerged as a multidisciplinary science and is being used in different fields for variety of applications. Several electrochemically synthesized nano composites of conducting polymers and nanoparticles of noble metals are promising electrode materials in fuel cells because of their electrocatalytic behavior. Room Temperature Ionic Liquids (RTILs) are the green solvents which have generated a lot of interest because of their broad electrochemical window which allows the reduction of ions with very high negative redox potentials on Pt, Au, glassy carbon electrodes etc., without significant hydrogen evolution. Therefore, RTILs are promising electrolytes for electrochemical studies on actinides and lanthanides. This issue includes two tutorial articles viz. Carbon nanotubes and its significance in electrochemistry and introduction to electrodeposition of metals and alloys. Papers relevant to INIS are indexed separately

Ultrahigh-vacuum in situ electrochemistry with solid polymer electrolyte and x-ray photoelectron spectroscopy studies of polypyrrole

International Nuclear Information System (INIS)

Skotheim, T.A.; Florit, M.I.; Melo, A.; O'Grady, W.E.

1984-01-01

A new in situ combined electrochemistry and x-ray-photoelectron-spectroscopy (XPS) technique using solid polymer electrolytes has been used to characterize electrically conducting films of polypyrrole perchlorate. The technique allows in situ electrochemical oxidation and reduction (doping and undoping) in ultrahigh vacuum and the simultaneous study of the polymer with XPS as a function of its electrochemical potential. We demonstrate that some anion species interact strongly electrostatically with the nitrogen heteroatoms. We also show conclusively that the electrochemistry of polypyrrole is highly irreversible

Study of the crystallographic phase change on copper (I) selenide thin films prepared through chemical bath deposition by varying the pH of the solution

Energy Technology Data Exchange (ETDEWEB)

Sandoval-Paz, M.G., E-mail: myrnasandoval@udec.cl [Departament of Physics, Faculty of Physical Sciences and Mathematics, University of Concepcion, Box 160-C, Concepción (Chile); Rodríguez, C.A. [Department of Materials Engineering, Faculty of Engineering, University of Concepción, Edmundo Larenas 270, Concepción 4070409 (Chile); Porcile-Saavedra, P.F. [Departament of Physics, Faculty of Physical Sciences and Mathematics, University of Concepcion, Box 160-C, Concepción (Chile); Trejo-Cruz, C. [Department of Physics, Faculty of Science, University of Biobío, Avenue Collao 1202, Box 5C, Concepción 4051381 (Chile)

2016-07-15

Copper (I) selenide thin films with orthorhombic and cubic structure were deposited on glass substrates by using the chemical bath deposition technique. The effects of the solution pH on the films growth and subsequently the structural, optical and electrical properties of the films were studied. Films with orthorhombic structure were obtained from baths wherein both metal complex and hydroxide coexist; while films with cubic structure were obtained from baths where the metal hydroxide there is no present. The structural modifications are accompanied by changes in bandgap energy, morphology and electrical resistivity of the films. - Graphical abstract: “Study of the crystallographic phase change on copper (I) selenide thin films prepared through chemical bath deposition by varying the pH of the solution” by M. G. Sandoval-Paz, C. A. Rodríguez, P. F. Porcile-Saavedra, C. Trejo-Cruz. Display Omitted - Highlights: • Copper (I) selenide thin films were obtained by chemical bath deposition. • Orthorhombic to cubic phase change was induced by varying the reaction solution pH. • Orthorhombic phase is obtained mainly from a hydroxides cluster mechanism. • Cubic phase is obtained mainly from an ion by ion mechanism. • Structural, optical and electrical properties are presented as a function of pH.

Enhanced performance of hybrid solar cells using longer arms of quantum cadmium selenide tetrapods

KAUST Repository

Lee, Kyu-Sung

2011-12-01

We demonstrate that enhanced device performance of hybrid solar cells based on tetrapod (TP)-shaped cadmium selenide (CdSe) nanoparticles and conjugated polymer of poly (3-hexylthiophene) (P3HT) can be obtained by using longer armed tetrapods which aids in better spatial connectivity, thus decreasing charge hopping events which lead to better charge transport. Longer tetrapods with 10 nm arm length lead to improved power conversion efficiency of 1.12% compared to 0.80% of device having 5 nm short-armed tetrapods:P3HT photoactive blends.

Enhanced Manifold of States Achieved in Heterostructures of Iron Selenide and Boron-Doped Graphene

Directory of Open Access Journals (Sweden)

Valentina Cantatore

2017-10-01

Full Text Available Enhanced superconductivity is sought by employing heterostructures composed of boron-doped graphene and iron selenide. Build-up of a composite manifold of near-degenerate noninteracting states formed by coupling top-of-valence-band states of FeSe to bottom-of-conduction-band states of boron-doped graphene is demonstrated. Intra- and intersubsystem excitons are explored by means of density functional theory in order to articulate a normal state from which superconductivity may emerge. The results are discussed in the context of electron correlation in general and multi-band superconductivity in particular.

Enhanced performance of hybrid solar cells using longer arms of quantum cadmium selenide tetrapods

KAUST Repository

Lee, Kyu-Sung; Kim, Inho; Gullapalli, Sravani; Wong, Michael S.; Jabbour, Ghassan E.

2011-01-01

We demonstrate that enhanced device performance of hybrid solar cells based on tetrapod (TP)-shaped cadmium selenide (CdSe) nanoparticles and conjugated polymer of poly (3-hexylthiophene) (P3HT) can be obtained by using longer armed tetrapods which aids in better spatial connectivity, thus decreasing charge hopping events which lead to better charge transport. Longer tetrapods with 10 nm arm length lead to improved power conversion efficiency of 1.12% compared to 0.80% of device having 5 nm short-armed tetrapods:P3HT photoactive blends.

A short introduction to digital simulations in electrochemistry: simulating the Cottrell experiment in NI LabVIEW

Directory of Open Access Journals (Sweden)

Soma Vesztergom

2018-05-01

Full Text Available A brief introduction to the use of digital simulations in electrochemistry is given by a detailed description of the simulation of Cottrell’s experiment in the LabVIEW programming language. A step-by-step approach is followed and different simulation techniques (explicit and implicit Euler, Runge–Kutta and Crank–Nicolson methods are applied. The applied techniques are introduced and discussed on the basis of Padé approximants. The paper might be found useful by undergraduate and graduate students familiarizing themselves with the digital simulation of electrochemical problems, as well as by university lecturers involved with the teaching of theoretical electrochemistry.

Mono and dinuclear rhodium, iridium and ruthenium complexes containing chelating 2,2´-bipyrimidine ligands: Synthesis, molecular structure, electrochemistry and catalytic properties

Czech Academy of Sciences Publication Activity Database

Govindaswamy, P.; Canivet, J.; Therrien, B.; Süss-Fink, G.; Štěpnička, P.; Ludvík, Jiří

2007-01-01

Roč. 692, č. 17 (2007), s. 3664-3675 ISSN 0022-328X R&D Projects: GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40400503 Keywords : arene ligands * electrochemistry * dinuclear complexes * transfer hydrogenation Subject RIV: CG - Electrochemistry Impact factor: 2.168, year: 2007

Hydroxylamine electrochemistry at low-index single-crystal platinum electrodes in acidic media

NARCIS (Netherlands)

Rosca, V.; Beltramo, G.L.; Koper, M.T.M.

2004-01-01

The electrochemistry of hydroxylamine at low-index single-crystal platinum electrodes in acidic media has been studied by voltammetry and in-situ FTIRRAS. Hydroxylamine (HAM) reactivity at platinum is largely controlled by interaction of the other components of the solution or products of the HAM

Semiconductor electrochemistry of coal pyrite. Final technical report, September 1990--September 1995

Energy Technology Data Exchange (ETDEWEB)

Osseo-Asare, K.; Wei, D.

1996-01-01

This project is concerned with the physiochemical processes occuring at the pyrite/aqueous interface, in the context of coal cleaning, desulfurization, and acid mine drainage. The use of synthetic particles of pyrite as model electrodes to investigate the semiconductor electrochemistry of pyrite is employed.

Photo-induced cooperative covalent-bond switching in amorphous arsenic selenide

Energy Technology Data Exchange (ETDEWEB)

Shpotyuk, O [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202, Stryjska str., Lviv, UA-290031 (Ukraine); Balitska, V [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202, Stryjska str., Lviv, UA-290031 (Ukraine); Filipecki, J [Institute of Physics of Jan Dlugosz University, 13/15, Al. Armii Krajowej, Czestochowa, PL-42201 (Poland)

2005-01-01

A microstructural mechanism of photoinduced transformations in amorphous arsenic selenide films was studied with IR Fourier-spectroscopy technique in 300-100 cm{sup -1} region. It was shown that stage of irreversible photostructural changes was connected with cooperative process of coordination defect formation accompanied by homopolar chemical bonds switching in heteropolar ones. On the contrary, reversible photoinduced effects were caused by heteropolar chemical bonds switching in homopolar ones, as well as additional channel of bridge heteropolar bonds switching in short-layer ones. The both processes were associated with formation of anomalously coordinated defect pairs and accompanying atomic displacements at the level of medium-range ordering. The developed mathematical simulation procedure testified in a favour of defect-related origin of the reversible photo-thermallyinduced transformations, since their kinetics corresponded to known stretched-exponential dependence, tending to bimolecular behaviour rather then to single-exponential one.

Impact electrochemistry on screen-printed electrodes for the detection of monodispersed silver nanoparticles of sizes 10-107 nm.

Science.gov (United States)

Nasir, Muhammad Zafir Mohamad; Pumera, Martin

2016-10-12

Impact electrochemistry provides a useful alternative technique for the detection of silver nanoparticles in solutions. The combined use of impact electrochemistry on screen-printed electrodes (SPEs) for the successful detection of silver nanoparticles provides an avenue for future on-site, point-of-care detection devices to be made for environmental, medicinal and biological uses. Here we discuss the use of screen-printed electrodes for the detection of well-defined monodispersed silver nanoparticles of sizes 10, 20, 40, 80, and 107 nm.

Blood glucose meters employing dynamic electrochemistry are stable against hematocrit interference in a laboratory setting.

Science.gov (United States)

Pfützner, Andreas; Musholt, Petra B; Schipper, Christina; Demircik, Filiz; Hengesbach, Carina; Flacke, Frank; Sieber, Jochen; Forst, Thomas

2013-11-01

Hematocrit (HCT) is known to be a confounding factor that interferes with many blood glucose (BG) measurement technologies, resulting in wrong readings. Dynamic electrochemistry has been identified as one possible way to correct for these potential deviations. The purpose of this laboratory investigation was to assess the HCT stability of four BG meters known to employ dynamic electrochemistry (BGStar and iBGStar, Sanofi; Wavesense Jazz, AgaMatrix; Wellion Linus, MedTrust) in comparison with three other devices (GlucoDock, Medisana; OneTouch Verio Pro, LifeScan; FreeStyle Freedom InsuLinx, Abbott-Medisense). Venous heparinized blood was immediately aliquoted after draw and manipulated to contain three different BG concentrations (60-90, 130-160, and 280-320 mg/dl) and five different HCT levels (25%, 35%, 45%, 55%, and 60%). After careful oxygenation to normal blood oxygen pressure, each of the resulting 15 different samples was measured six times with three devices and three strip lots of each meter. The YSI Stat 2300 served as laboratory reference method. Stability to HCT influence was assumed when less than 10% difference occurred between the highest and lowest mean glucose deviations in relation to HCT concentrations [hematocrit interference factor (HIF)]. Five of the investigated self-test meters showed a stable performance with the different HCT levels tested in this investigation: BGStar (HIF 4.6%), iBGStar (6.6%), Wavesense Jazz (4.1%), Wellion Linus (8.5%), and OneTouch Verio Pro (6.2%). The two other meters were influenced by HCT (FreeStyle InsuLinx 17.8%; GlucoDock 46.5%). In this study, meters employing dynamic electrochemistry, as used in the BGStar and iBGStar devices, were shown to correct for potential HCT influence on the meter results. Dynamic electrochemistry appears to be an effective way to handle this interfering condition. © 2013 Diabetes Technology Society.

Blood Glucose Meters Employing Dynamic Electrochemistry Are Stable against Hematocrit Interference in a Laboratory Setting

Science.gov (United States)

Pfützner, Andreas; Musholt, Petra B.; Schipper, Christina; Demircik, Filiz; Hengesbach, Carina; Flacke, Frank; Sieber, Jochen; Forst, Thomas

2013-01-01

Background Hematocrit (HCT) is known to be a confounding factor that interferes with many blood glucose (BG) measurement technologies, resulting in wrong readings. Dynamic electrochemistry has been identified as one possible way to correct for these potential deviations. The purpose of this laboratory investigation was to assess the HCT stability of four BG meters known to employ dynamic electrochemistry (BGStar and iBGStar, Sanofi; Wavesense Jazz, AgaMatrix; Wellion Linus, MedTrust) in comparison with three other devices (GlucoDock, Medisana; OneTouch Verio Pro, LifeScan; FreeStyle Freedom InsuLinx, Abbott-Medisense). Methods Venous heparinized blood was immediately aliquoted after draw and manipulated to contain three different BG concentrations (60–90, 130–160, and 280–320 mg/dl) and five different HCT levels (25%, 35%, 45%, 55%, and 60%). After careful oxygenation to normal blood oxygen pressure, each of the resulting 15 different samples was measured six times with three devices and three strip lots of each meter. The YSI Stat 2300 served as laboratory reference method. Stability to HCT influence was assumed when less than 10% difference occurred between the highest and lowest mean glucose deviations in relation to HCT concentrations [hematocrit interference factor (HIF)]. Results Five of the investigated self-test meters showed a stable performance with the different HCT levels tested in this investigation: BGStar (HIF 4.6%), iBGStar (6.6%), Wavesense Jazz (4.1%), Wellion Linus (8.5%), and OneTouch Verio Pro (6.2%). The two other meters were influenced by HCT (FreeStyle InsuLinx 17.8%; GlucoDock 46.5%). Conclusions In this study, meters employing dynamic electrochemistry, as used in the BGStar and iBGStar devices, were shown to correct for potential HCT influence on the meter results. Dynamic electrochemistry appears to be an effective way to handle this interfering condition. PMID:24351179

Transition metal oxide nanopowder and ionic liquid: an efficient system for the synthesis of diorganyl selenides, selenocysteine and derivatives

Energy Technology Data Exchange (ETDEWEB)

Narayanaperumal, Senthil; Gul, Kashif; Kawasoko, Cristiane Y.; Singh, Devender; Dornelles, Luciano; Rodrigues, Oscar E.D. [Universidade Federal de Santa Maria (UFSC), RS (Brazil). Dept. de Quimica. LabSelen-NanoBio; Braga, Antonio L. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Quimica. LabSelen

2010-07-01

We have developed an efficient method for the synthesis of diorganyl selenides and {beta}-seleno amines using Zn, catalytic amounts of ZnO nanopowder, as a catalyst and ionic liquid as a recyclable solvent. This ZnO/ionic liquid system shows high efficiency in catalyzing these transformations with the formation of the desired products in high yields. (author)

Understanding oxygen electrochemistry in aprotic LiO2 batteries

Directory of Open Access Journals (Sweden)

Liang Wang

2017-07-01

Full Text Available In the past decade, the aprotic lithium–oxygen (LiO2 battery has generated a great deal of interest because theoretically it can store more energy than today's lithium-ion batteries. Although considerable research efforts have been devoted to the R&D of this potentially disruptive technology, many scientific and engineering obstacles still remain to be addressed before a practical device could be realized. In this review, we summarize recent advances in the fundamental understanding of the O2 electrochemistry in LiO2 batteries, including the O2 reduction to Li2O2 on discharge and the reverse Li2O2 oxidation on recharge and factors that exert strong influences on the redox of O2/Li2O2. In addition, challenges and perspectives are also provided for the future study of LiO2 batteries. Keywords: Lithium–oxygen battery, Oxygen electrochemistry, Mechanism

Detailed H2 and CO Electrochemistry for a MEA Model Fueled by Syngas

KAUST Repository

Lee, W. Y.; Ong, K. M.; Ghoniem, A. F.

2015-01-01

© The Electrochemical Society. SOFCs can directly oxidize CO in addition to H2, which allows them to be coupled to a gasifier. Many membrane-electrode-assembly (MEA) models neglect CO electrochemistry due to sluggish kinetics and the water

Organic molecules passivated Mn doped Zinc Selenide quantum dots and its properties

International Nuclear Information System (INIS)

Archana, J.; Navaneethan, M.; Ponnusamy, S.; Hayakawa, Y.; Muthamizhchelvan, C.

2011-01-01

Quantum dots of Mn doped Zinc Selenide with N-Methylaniline as the capping agent was prepared by simple and inexpensive wet chemical method. Size of the particles observed by TEM was of the order of 2-4 nm which was well consistent with the size measured by UV analysis. The presence of paramagnetic substance Mn 2+ in the ZnSe quantum dots was confirmed by EPR measurement. Mn doped ZnSe nanoparticles exhibited a strong blue emission that was strongly dependent upon the Mn dopant level and the surface passivation produced by N-Methylaniline. The stability of the product was studied by thermal analysis which shows that this product is highly suitable for opto-electronic applications.

The 1,4-diazabutadiene/1,2-enediamido non-innocent ligand system in the formation of iridaheteroaromatic compounds: Spectroelectrochemistry and electronic structure

Czech Academy of Sciences Publication Activity Database

Kaim, A.; Sieger, M.; Greulich, S.; Sarkar, B.; Fiedler, Jan; Záliš, Stanislav

2010-01-01

Roč. 695, č. 7 (2010), s. 1052-1058 ISSN 0022-328X R&D Projects: GA AV ČR KAN100400702; GA MŠk OC 139; GA MŠk OC09043 Institutional research plan: CEZ:AV0Z40400503 Keywords : 1,4-diazabutadiene * electronic structure * iridium compounds Subject RIV: CG - Electrochemistry Impact factor: 2.205, year: 2010

Fluorescence imaging technology (FI) for high-throughput screening of selenide-modified nano-TiO2 catalysts.

Science.gov (United States)

Wang, Liping; Lee, Jianchao; Zhang, Meijuan; Duan, Qiannan; Zhang, Jiarui; Qi, Hailang

2016-02-18

A high-throughput screening (HTS) method based on fluorescence imaging (FI) was implemented to evaluate the catalytic performance of selenide-modified nano-TiO2. Chemical ink-jet printing (IJP) technology was reformed to fabricate a catalyst library comprising 1405 (Ni(a)Cu(b)Cd(c)Ce(d)In(e)Y(f))Se(x)/TiO2 (M6Se/Ti) composite photocatalysts. Nineteen M6Se/Tis were screened out from the 1405 candidates efficiently.

7. International Frumkin Symposium. Basic electrochemistry for science and technology. Abstracts. Part 2

International Nuclear Information System (INIS)

2000-01-01

Modern tendencies of development of electrochemistry as in regions of fundamental investigations so in applied directions are presented. Basic themes of reports presented are: electrocatalysis and electrosynthesis, batteries and supercapacitors, corrosion and electrodeposition, electrolytes and membranes, biosensors and electroanalysis, nanoelectrochemistry [ru

Electrochemistry at the edge of a single graphene layer in a nanopore

DEFF Research Database (Denmark)

Banerjee, Sutanuka; Shim, Jeong; Rivera, J.

2013-01-01

We study the electrochemistry of single layer graphene edges using a nanopore-based structure consisting of stacked graphene and AlO dielectric layers. Nanopores, with diameters ranging from 5 to 20 nm, are formed by an electron beam sculpting process on the stacked layers. This leads to a unique...

Electrochemistry and Spectroelectrochemistry of the Pu (III/IV) and (IV/VI) Couples in Nitric Acid Systems

Energy Technology Data Exchange (ETDEWEB)

Lines, Amanda M. [Nuclear Chemistry and Engineering, Pacific Northwest National Laboratory, Richland WA 99352; Adami, Susan R. [Nuclear Chemistry and Engineering, Pacific Northwest National Laboratory, Richland WA 99352; Casella, Amanda J. [Nuclear Chemistry and Engineering, Pacific Northwest National Laboratory, Richland WA 99352; Sinkov, Sergey I. [Nuclear Chemistry and Engineering, Pacific Northwest National Laboratory, Richland WA 99352; Lumetta, Gregg J. [Nuclear Chemistry and Engineering, Pacific Northwest National Laboratory, Richland WA 99352; Bryan, Samuel A. [Nuclear Chemistry and Engineering, Pacific Northwest National Laboratory, Richland WA 99352

2017-09-20

The solution chemistry of Pu in nitric acid is explored via electrochemistry and spectroelectrochemistry. By utilizing and comparing these techniques, an improved understanding of Pu behavior and its dependence on nitric acid concentration can be achieved. Here the Pu (III/IV) couple is characterized using cyclic voltammetry, square wave voltammetry, and a spectroelectrochemical Nernst step. Results indicate the formal reduction potential of the couple shifts negative with increasing acid concentration and reversible electrochemistry is no longer attainable above 6 M HNO3. Spectroelectrochemistry is also used to explore the irreversible oxidation of Pu(IV) to Pu(VI) and shine light on the mechanism and acid dependence of the redox reaction.

Photothermal deflection spectroscopy investigations of uranium electrochemistry

International Nuclear Information System (INIS)

Russo, R.E.; Rudnicki, J.D.

1993-01-01

Photothermal Deflection Spectroscopy (PDS) has been successfully applied to the study of uranium oxide electrochemistry. A brief description of PDS and preliminary results that demonstrate the technique are presented. Concentration gradients formed at the electrode surface are measured by this technique. The gradients give insight into the reaction mechanisms. There is some evidence of the initiation of non-electrochemical dissolution of the uranium oxide. Optical absorption by the uranium oxide is measured by PDS and the first results indicate that the absorption of the surface does not change during electrochemical experiments. This result is contrary to literature measurements of bulk samples that indicate that the optical absorption should be strongly changing

Influence of the substituents on the electronic and electrochemical properties of a new square-planar nickel-bis(quinoxaline-6,7-dithiolate) system: synthesis, spectroscopy, electrochemistry, crystallography, and theoretical investigation.

Science.gov (United States)

Bolligarla, Ramababu; Reddy, Samala Nagaprasad; Durgaprasad, Gummadi; Sreenivasulu, Vudagandla; Das, Samar K

2013-01-07

We describe the synthesis, crystal structures, electronic absorption spectra, and electrochemistry of a series of square-planar nickel-bis(quinoxaline-6,7-dithiolate) complexes with the general formula [Bu(4)N](2)[Ni(X(2)6,7-qdt)(2)], where X = H (1a), Ph (2a), Cl (3), and Me (4). The solution and solid-state electronic absorption spectral behavior and electrochemical properties of these compounds are strongly dependent on the electron donating/accepting nature of the substituent X, attached to the quinoxaline-6,7-dithiolate ring in the system [Bu(4)N](2)[Ni(X(2)6,7-qdt)(2)]. Particularly, the charge transfer (CT) transition bands observed in the visible region are greatly affected by the electronic nature of the substituent. A possible explanation for this influence of the substituents on electronic absorption and electrochemistry is described based on highest occupied molecular orbital (HOMO) to lowest unoccupied molecular orbital (LUMO) gaps, which is further supported by ground-state electronic structure calculations. In addition to this, the observed CT bands in all the complexes are sensitive to the solvent polarity. Interestingly, compounds 1a, 2a, 3, and 4 undergo reversible oxidation at very low oxidation potentials appearing at E(1/2) = +0.12 V, 0.033 V, 0.18 V, and 0.044 V vs Ag/AgCl, respectively, in MeOH solutions, corresponding to the respective couples [Ni(X(2)6,7-qdt)(2)](-)/[Ni(X(2)6,7-qdt)(2)](2-). Compounds 1a, 3, and 4 have been characterized unambiguously by single crystal X-ray structural analysis; compound 2a could not be characterized by single crystal X-ray structure determination because of the poor quality of the concerned crystals. Thus, we have synthesized the tetraphenyl phosphonium salt of the complex anion of 2a, [PPh(4)](2)[Ni(Ph(2)6,7-qdt)(2)]·3DMF (2b) for its structural characterization.

Electrochemistry and spectro-electrochemistry of dithizonatophenylmercury(II)

International Nuclear Information System (INIS)

Eschwege, Karel G. von; As, Lydia van; Swarts, Jannie C.

2011-01-01

Graphical abstract: Display Omitted Highlights: → CV and spectroelectrochemistry of dithizone and PhHgHDz, 3, is presented. → CV shows 3 has stable metal thioether (Hg-S-C), 1 oxidation and two reductions. → 3 is photochromic (t 1/2, relaxation = 1300 s). → Electrochemistry of ground and photo-activated 3 is identical. → Spectroelectrochemistry of 3 highlights electrochromism. - Abstract: The reactions between dithizone (H 2 Dz, (1)) or potassium dithizonate (K + HDz - , (2)) and phenylmercury(II) chloride gives PhHg(HDz), (3). Complex (3) is photochromic. In dichloromethane, the blue photo-exited state of (3) exhibits a first order relaxation process to regenerate the orange ground state with rate constant 0.00053 s -1 . The half life of this relaxation is ca. 1300 s. Electrochemically, on cyclic voltammetry time scale, the oxidations of (1) and (3) are different. A comparative voltammetric and spectro-electrochemical study of (1) and (3) in CH 2 Cl 2 containing 0.1 mol dm -3 [N( n Bu) 4 ][B(C 6 F 5 ) 4 ] revealed that the mercapto group of (1) can be oxidised in two one-electron transfer steps. A disulphide is first produced and then in a second oxidation step, HDz + is formed. In contrast, complex (3) shows only one ligand-based oxidation step. Upon complexation with phenylmercury the free mercaptan group of (1) becomes a stable 'metal thioether', Hg-S-C, which effectively prevents disulphide formation in (3) upon electrochemical oxidation. Both (1) and (3) shows two reduction steps. The electrochemical fingerprint of blue photo-excited (3) is identical to that of the orange ground state as no new functional groups are introduced upon irradiation; only bond rotation occurs. The different electronic spectra for each of the redox states of (3), obtained from spectro-electrochemical measurements, revealed that only the (3)/(3 - ) couple exhibits electrochromic properties.

Electrochemistry in the mimicry of oxidative drug metabolism by cytochrome P450s.

Science.gov (United States)

Nouri-Nigjeh, Eslam; Bischoff, Rainer; Bruins, Andries P; Permentier, Hjalmar P

2011-05-01

Prediction of oxidative drug metabolism at the early stages of drug discovery and development requires fast and accurate analytical techniques to mimic the in vivo oxidation reactions by cytochrome P450s (CYP). Direct electrochemical oxidation combined with mass spectrometry, although limited to the oxidation reactions initiated by charge transfer, has shown promise in the mimicry of certain CYP-mediated metabolic reactions. The electrochemical approach may further be utilized in an automated manner in microfluidics devices facilitating fast screening of oxidative drug metabolism. A wide range of in vivo oxidation reactions, particularly those initiated by hydrogen atom transfer, can be imitated through the electrochemically-assisted Fenton reaction. This reaction is based on O-O bond activation in hydrogen peroxide and oxidation by hydroxyl radicals, wherein electrochemistry is used for the reduction of molecular oxygen to hydrogen peroxide, as well as the reduction of Fe(3+) to Fe(2+). Metalloporphyrins, as surrogates for the prosthetic group in CYP, utilizing metallo-oxo reactive species, can also be used in combination with electrochemistry. Electrochemical reduction of metalloporphyrins in solution or immobilized on the electrode surface activates molecular oxygen in a manner analogous to the catalytical cycle of CYP and different metalloporphyrins can mimic selective oxidation reactions. Chemoselective, stereoselective, and regioselective oxidation reactions may be mimicked using electrodes that have been modified with immobilized enzymes, especially CYP itself. This review summarizes the recent attempts in utilizing electrochemistry as a versatile analytical and preparative technique in the mimicry of oxidative drug metabolism by CYP. © 2011 Bentham Science Publishers Ltd.

Electrochemistry of Single Metalloprotein and DNA‐Based Molecules at Au(111) Electrode Surfaces

DEFF Research Database (Denmark)

Salvatore, Princia; Zeng, Dongdong; Karlsen, Kasper Kannegård

2013-01-01

We have briefly overviewed recent efforts in the electrochemistry of single transition metal complex, redox metalloprotein, and redox‐marked oligonucleotide (ON) molecules. We have particularly studied self‐assembled molecular monolayers (SAMs) of several 5′‐C6‐SH single‐ (ss) and double‐strand (...

Inquiry-Based Laboratory Activities in Electrochemistry: High School Students' Achievements and Attitudes

Science.gov (United States)

Sesen, Burcin Acar; Tarhan, Leman

2013-01-01

This study aimed to investigate the effects of inquiry-based laboratory activities on high school students' understanding of electrochemistry and attitudes towards chemistry and laboratory work. The participants were 62 high school students (average age 17 years) in an urban public high school in Turkey. Students were assigned to experimental (N =…

Metal-air batteries: from oxygen reduction electrochemistry to cathode catalysts.

Science.gov (United States)

Cheng, Fangyi; Chen, Jun

2012-03-21

Because of the remarkably high theoretical energy output, metal-air batteries represent one class of promising power sources for applications in next-generation electronics, electrified transportation and energy storage of smart grids. The most prominent feature of a metal-air battery is the combination of a metal anode with high energy density and an air electrode with open structure to draw cathode active materials (i.e., oxygen) from air. In this critical review, we present the fundamentals and recent advances related to the fields of metal-air batteries, with a focus on the electrochemistry and materials chemistry of air electrodes. The battery electrochemistry and catalytic mechanism of oxygen reduction reactions are discussed on the basis of aqueous and organic electrolytes. Four groups of extensively studied catalysts for the cathode oxygen reduction/evolution are selectively surveyed from materials chemistry to electrode properties and battery application: Pt and Pt-based alloys (e.g., PtAu nanoparticles), carbonaceous materials (e.g., graphene nanosheets), transition-metal oxides (e.g., Mn-based spinels and perovskites), and inorganic-organic composites (e.g., metal macrocycle derivatives). The design and optimization of air-electrode structure are also outlined. Furthermore, remarks on the challenges and perspectives of research directions are proposed for further development of metal-air batteries (219 references).

Controllable synthesis of metal selenide heterostructures mediated by Ag2Se nanocrystals acting as catalysts

Science.gov (United States)

Zhou, Jiangcong; Huang, Feng; Xu, Ju; Wang, Yuansheng

2013-09-01

Ag2Se nanocrystals were demonstrated to be novel semiconductor mediators, or in other word catalysts, for the growth of semiconductor heterostructures in solution. This is a result of the unique feature of Ag2Se as a fast ion conductor, allowing foreign cations to dissolve and then to heterogrow the second phase. Using Ag2Se nanocrystals as catalysts, dimeric metal selenide heterostructures such as Ag2Se-CdSe and Ag2Se-ZnSe, and even multi-segment heterostructures such as Ag2Se-CdSe-ZnSe and Ag2Se-ZnSe-CdSe, were successfully synthesized. Several interesting features were found in the Ag2Se based heterogrowth. At the initial stage of heterogrowth, a layer of the second phase forms on the surface of an Ag2Se nanosphere, with a curved junction interface between the two phases. With further growth of the second phase, the Ag2Se nanosphere tends to flatten the junction surface by modifying its shape from sphere to hemisphere in order to minimize the conjunct area and thus the interfacial energy. Notably, the crystallographic relationship of the two phases in the heterostructure varies with the lattice parameters of the second phase, in order to reduce the lattice mismatch at the interface. Furthermore, a small lattice mismatch at the interface results in a straight rod-like second phase, while a large lattice mismatch would induce a tortuous product. The reported results may provide a new route for developing novel selenide semiconductor heterostructures which are potentially applicable in optoelectronic, biomedical, photovoltaic and catalytic fields.Ag2Se nanocrystals were demonstrated to be novel semiconductor mediators, or in other word catalysts, for the growth of semiconductor heterostructures in solution. This is a result of the unique feature of Ag2Se as a fast ion conductor, allowing foreign cations to dissolve and then to heterogrow the second phase. Using Ag2Se nanocrystals as catalysts, dimeric metal selenide heterostructures such as Ag2Se-CdSe and Ag2Se

The mechanism of the nano-CeO2 films deposition by electrochemistry method as coated conductor buffer layers

International Nuclear Information System (INIS)

Lu, Yuming; Cai, Shuang; Liang, Ying; Bai, Chuanyi; Liu, Zhiyong; Guo, Yanqun; Cai, Chuanbing

2015-01-01

Highlights: • Crack-free CeO 2 film thicker than 200 nm was prepared on NiW substrate by ED method. • Different electrochemical processes as hydroxide/metal mechanisms were identified. • The CeO 2 precursor films deposited by ED method were in nano-scales. - Abstract: Comparing with conventional physical vapor deposition methods, electrochemistry deposition technique shows a crack suppression effect by which the thickness of CeO 2 films on Ni–5 at.%W substrate can reach a high value up to 200 nm without any cracks, make it a potential single buffer layer for coated conductor. In the present work, the processes of CeO 2 film deposited by electrochemistry method are detailed investigated. A hydroxide reactive mechanism and an oxide reactive mechanism are distinguished for dimethyl sulfoxide and aqueous solution, respectively. Before heat treatment to achieve the required bi-axial texture performance of buffer layers, the precursor CeO 2 films are identified in nanometer scales. The crack suppression for electrochemistry deposited CeO 2 films is believed to be attributed to the nano-effects of the precursors

Polyamide–thallium selenide composite materials via temperature and pH controlled adsorption–diffusion method

International Nuclear Information System (INIS)

Ivanauskas, Remigijus; Samardokas, Linas; Mikolajunas, Marius; Virzonis, Darius; Baltrusaitis, Jonas

2014-01-01

Graphical abstract: Single phase polyamide–thallium selenide hybrid functional materials were synthesized for solar energy conversion. - Highlights: • Thallium selenide–polyamide composite materials surfaces synthesized. • Mixed phase composition confirmed by XRD. • Increased temperature resulted in a denser surface packing. • Urbach energies correlated with AFM showing decreased structural disorder. • Annealing in N 2 at 100 °C yielded a single TlSe phase. - Abstract: Composite materials based on III–VI elements are promising in designing efficient photoelectronic devices, such as thin film organic–inorganic solar cells. In this work, TlSe composite materials were synthesized on a model polymer polyamide using temperature and pH controlled adsorption–diffusion method via (a) selenization followed by (b) the exposure to the group III metal (Tl) salt solution and their surface morphological, chemical and crystalline phase information was determined with particular focus on their corresponding structure–optical property relationship. XRD analysis yielded a complex crystalline phase distribution which correlated well with the optical and surface morphological properties measured. pH 11.3 and 80 °C yielded well defined, low structural disorder composite material surface. After annealing in N 2 at 100 °C, polycrystalline PA-Tl x Se y composite materials yielded a single TlSe phase due to the enhanced diffusion and reaction of thallium ions into the polymer. The method described here can be used to synthesize variety of binary III–VI compounds diffused into the polymer at relatively low temperatures and low overall cost, thus providing for a flexible synthesis route for novel composite solar energy harvesting materials

Recent advances in electrochemical detection of important sulfhydryl-containing compounds

Czech Academy of Sciences Publication Activity Database

Zlámalová, Magda; Nesměrák, K.

2016-01-01

Roč. 147, č. 8 (2016), s. 1331-1338 ISSN 0026-9247 Institutional support: RVO:61388955 Keywords : electrochemistry * electrochemical detection * thiol Subject RIV: CG - Electrochemistry Impact factor: 1.282, year: 2016

Scanning thermo-ionic microscopy for probing local electrochemistry at the nanoscale

Energy Technology Data Exchange (ETDEWEB)

Eshghinejad, Ahmadreza; Nasr Esfahani, Ehsan; Wang, Peiqi; Li, Jiangyu, E-mail: jjli@uw.edu [Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States); Xie, Shuhong [Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, Hunan (China); Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong (China); Geary, Timothy C.; Adler, Stuart B. [Department of Chemical Engineering, University of Washington, Seattle, Washington 98195 (United States)

2016-05-28

Conventional electrochemical characterization techniques based on voltage and current measurements only probe faradaic and capacitive rates in aggregate. In this work we develop a scanning thermo-ionic microscopy (STIM) to probe local electrochemistry at the nanoscale, based on imaging of Vegard strain induced by thermal oscillation. It is demonstrated from both theoretical analysis and experimental validation that the second harmonic response of thermally induced cantilever vibration, associated with thermal expansion, is present in all solids, whereas the fourth harmonic response, caused by local transport of mobile species, is only present in ionic materials. The origin of STIM response is further confirmed by its reduced amplitude with respect to increased contact force, due to the coupling of stress to concentration of ionic species and/or electronic defects. The technique has been applied to probe Sm-doped Ceria and LiFePO{sub 4}, both of which exhibit higher concentrations of mobile species near grain boundaries. The STIM gives us a powerful method to study local electrochemistry with high sensitivity and spatial resolution for a wide range of ionic systems, as well as ability to map local thermomechanical response.

Metallurgical electrochemistry: the interface between materials science and molten salt chemistry

International Nuclear Information System (INIS)

Sadoway, D.R.

1991-01-01

Even though molten salt electrolysis finds application in the primary extraction of metals (electrowinning), the purification and recycling of metals (electrorefining), and in the formation of metal coatings (electroplating), the technology remains in many respects underexploited. Electrolysis in molten salts as well as other nonaqueous media has enormous potential for materials processing. First, owing to the special attributes of nonaqueous electrolytes electrochemical processing in these media has an important role to play in the generation of advanced materials, i.e., materials with specialized chemistries or tailored microstructures (electrosynthesis). Secondly, as environmental quality standards rise beyond the capabilities of classical metals extraction technologies to comply, molten salt electrolysis may prove to be the only acceptable route from ore to metal. Growing public awareness of pollution from the metals industry could stimulate a renaissance in molten salt electrochemistry. Challenges facing metallurgical electrochemistry as relates to the environment fall into two categories: (1) improving existing electrochemical technology, and (2) developing clean electrochemical technology to displace current nonelectrochemical technology. In both instances success hinges upon the discovery of advanced materials and the ecologically sound extraction of metals, the close coupling between materials science and molten salt chemistry is manifest. (author) 6 refs

In-situ Raman spectroscopy to elucidate the influence of adsorption in graphene electrochemistry

NARCIS (Netherlands)

van den Beld, Wesley T. E.; Odijk, Mathieu; Vervuurt, Rene H. J.; Weber, Jan-Willem; Bol, Ageeth A.; van den Berg, Albert; Eijkel, Jan C. T.

2017-01-01

Electrochemistry on graphene is of particular interest due to graphene’s high surface area, high electrical conductivity and low interfacial capacitance. Because the graphene Fermi level can be probed by its strong Raman signal, information on the graphene doping can be obtained which in turn can

Low temperature electrochemistry at normal conductor/frozen electrolyte interface

International Nuclear Information System (INIS)

Borkowska, Z.; Stimming, U.

1991-01-01

The frozen electrolyte technique (FREECE = FRozen Electrolyte ElectroChEmistry) is based on the experimental result that frozen electrolytes are suitable for electrochemical studies. This technique has been used in our laboratory and also by others to investigate interfacial electrochemical behavior. An argument will be given as to why the FREECE technique is advantageous in a number of respects and what kind of electrolyte systems can be used. Reference is made to electrochemical results such as interfacial reactions and double layer properties. 26 refs

Lead Selenide Nanostructures Self-Assembled across Multiple Length Scales and Dimensions

Directory of Open Access Journals (Sweden)

Evan K. Wujcik

2016-01-01

Full Text Available A self-assembly approach to lead selenide (PbSe structures that have organized across multiple length scales and multiple dimensions has been achieved. These structures consist of angstrom-scale 0D PbSe crystals, synthesized via a hot solution process, which have stacked into 1D nanorods via aligned dipoles. These 1D nanorods have arranged into nanoscale 2D sheets via directional short-ranged attraction. The nanoscale 2D sheets then further aligned into larger 2D microscale planes. In this study, the authors have characterized the PbSe structures via normal and cryo-TEM and EDX showing that this multiscale multidimensional self-assembled alignment is not due to drying effects. These PbSe structures hold promise for applications in advanced materials—particularly electronic technologies, where alignment can aid in device performance.

Novel urchin-like In2O3–chitosan modified electrode for direct electrochemistry of glucose oxidase and biosensing

International Nuclear Information System (INIS)

Yang Zhanjun; Huang Xiaochun; Zhang Rongcai; Li Juan; Xu Qin; Hu Xiaoya

2012-01-01

Highlights: ► The urchin-like In 2 O 3 –CS film is proposed for the immobilization of protein. ► The direct electrochemistry of glucose oxidase and biosensing was studied. ► The constructed glucose biosensor shows excellent performances. ► This matrix provides a new and efficient approach for the direct electrochemistry. - Abstract: A novel urchin-like In 2 O 3 –chitosan modified glassy carbon electrode (GCE) is for the first time prepared. The direct electrochemistry of glucose oxidase (GOD) immobilized on the surface of modified GCE and biosensing are studied. The urchin-like In 2 O 3 nanostructure-based matrix has large specific surface area and provides a favorable and biocompatible microenvironment for promoting the direct electron transfer between proteins and electrode surface. The properties of different modified electrode are characterized by scanning electron microscopy (SEM), electrochemical impedance spectra (EIS), UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and cyclic voltammetry, respectively. The constructed glucose biosensor shows wide linear range (5.0 × 10 −6 to 1.3 × 10 −3 M), low detection limit (1.9 × 10 −6 M), a Michaelis–Menten constant of 0.37 mM. The proposed biosensor has good sensitivity, excellent selectivity, good reproducibility and stability. This urchin-like In 2 O 3 –chitosan matrix provides a new approach and efficient matrix for the direct electrochemistry of proteins and developing novel types of biosensors.

Cytocompatibility of direct water synthesized cadmium selenide quantum dots in colo-205 cells

Energy Technology Data Exchange (ETDEWEB)

Rodriguez-Torres, Marcos R. [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States); Velez, Christian; Zayas, Beatriz [Universidad Metropolitana, ChemTox Laboratory, School of Environmental Affairs (United States); Rivera, Osvaldo [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States); Arslan, Zikri [Jackson State University, Department of Chemistry (United States); Gonzalez-Vega, Maxine N. [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States); Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Morell, Gerardo [University of Puerto Rico, Molecular Science Research Center (United States); Primera-Pedrozo, Oliva M., E-mail: oprimera1@suagm.edu [Universidad Metropolitana, Nanomaterials Science Laboratory, School of Science and Technology (United States)

2015-06-15

Cadmium selenide quantum dots (CdSe QDs), inorganic semiconducting nanocrystals, are alluring increased attraction due to their highly refined chemistry, availability, and super tunable optical properties suitable for many applications in different research areas, such as photovoltaics, light-emitting devices, environmental sciences, and nanomedicine. Specifically, they are being widely used in bio-imaging in contrast to organic dyes due to their high brightness and improved photo-stability, and their ability to tune their absorption and emission spectra upon changing the crystal size. The production of CdSe QDs is mostly assisted by trioctylphosphine oxide compound, which acts as solvent or solubilizing agent and renders the QDs soluble in organic compounds (such as toluene, chloroform, and hexane) that are highly toxic. To circumvent the toxicity-related factor in CdSe QDs, we report the synthesis of CdSe QDs capped with thioglycolic acid (TGA) in an aqueous medium, and their biocompatibility in colo-205 cancer cells. In this study, the [Cd{sup 2+}]/[TGA] ratio was adjusted to 11:1 and the Se concentration (10 and 15 mM) was monitored in order to evaluate its influence on the optical properties and cytocompatibility. QDs resulted to be quite stable in water (after purification) and RPMI cell medium and no precipitation was observed for long contact times, making them appealing for in vitro experiments. The spectroscopy analysis, advanced electron microscopy, and X-ray diffractometry studies indicate that the final products were successfully formed exhibiting an improved optical response. Colo-205 cells being exposed to different concentrations of TGA-capped CdSe QDs for 12, 24, and 48 h with doses ranging from 0.5 to 2.0 mM show high tolerance reaching cell viabilities as high as 93 %. No evidence of cellular apoptotic pathways was observed as pointed out by our Annexin V assays at higher concentrations. Moreover, confocal microscopy analysis conducted to

Thermodynamic data for uranium and thorium intermetallic compounds: A historical perspective

International Nuclear Information System (INIS)

Alcock, C.B.

1989-01-01

The development of quantitative information concerning the stabilities of uranium and thorium intermetallic compounds since the publication of Rough and Bauer's phase diagram compilation are reviewed. During this era a number of high temperature measurement techniques have been developed, from gas/solid equilibration to mass spectrometry and from high temperature calorimetry to solid state electrochemistry, and the growth of quantitative information has run parallel to this evolution. The amount of experimental effort now appears to be declining, and the task presently of major importance is to integrate and rationalize the quantitative information, an effort which will undoubtedly lead to new experimental initiatives. (orig.)

Implementation of Case-Based Instruction on Electrochemistry at the 11th Grade Level

Science.gov (United States)

Tarkin, Aysegul; Uzuntiryaki-Kondakci, Esen

2017-01-01

This study aims to compare the effectiveness of case-based instruction over traditional instruction in improving 11th grade students' understanding of electrochemistry concepts, attitudes toward chemistry, chemistry self-efficacy beliefs, and motivation to learn chemistry. In total, 113 students (47 males and 66 females) from three high schools…

Synthesis and characterization of (Ni{sub 1−x}Co{sub x})Se{sub 2} based ternary selenides as electrocatalyst for triiodide reduction in dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Theerthagiri, J.; Senthil, R.A. [Solar Energy Lab, Department of Chemistry, Thiruvalluvar University, Vellore 632115 (India); Buraidah, M.H. [Centre for Ionics University of Malaya, Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia); Raghavender, M. [Department of Physics, Yogi Vemana University, Kadapa 516003, Andhra Pradesh (India); Madhavan, J., E-mail: jagan.madhavan@gmail.com [Solar Energy Lab, Department of Chemistry, Thiruvalluvar University, Vellore 632115 (India); Arof, A.K. [Centre for Ionics University of Malaya, Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia)

2016-06-15

Ternary metal selenides of (Ni{sub 1−x}Co{sub x})Se{sub 2} with 0≤x≤1 were synthesized by using one-step hydrothermal reduction route. The synthesized metal selenides were utilized as an efficient, low-cost platinum free counter electrode for dye-sensitized solar cells. The cyclic voltammetry and electrochemical impedance spectroscopy studies revealed that the Ni{sub 0.5}Co{sub 0.5}Se{sub 2} counter electrode exhibited higher electrocatalytic activity and lower charge transfer resistance at the counter electrode/electrolyte interface than the other compositions for reduction of triiodide to iodide. Ternary selenides of Ni{sub 0.5}Co{sub 0.5}Se{sub 2} offer a synergistic effect to the electrocatalytic activity for the reduction of triiodide that might be due to an increase in active catalytic sites and small charge transfer resistance. The DSSC with Ni{sub 0.5}Co{sub 0.5}Se{sub 2} counter electrode achieved a high power conversion efficiency of 6.02%, which is comparable with that of conventional platinum counter electrode (6.11%). This present investigation demonstrates the potential application of Ni{sub 0.5}Co{sub 0.5}Se{sub 2} as counter electrode in dye-sensitized solar cells.

Remarkable photo-catalytic degradation of malachite green by nickel doped bismuth selenide under visible light irradiation

International Nuclear Information System (INIS)

Kulsi, Chiranjit; Ghosh, Amrita; Mondal, Anup; Kargupta, Kajari; Ganguly, Saibal; Banerjee, Dipali

2017-01-01

Highlights: • Bi_2Se_3 and Ni doped Bi_2Se_3 were synthesized by solvothermal approach. • Presence of nickel was confirmed by X-ray photoelectron spectroscopy (XPS) measurement. • Complete degradation of malachite green (MG) dye was achieved by Ni doped Bi_2Se_3 with H_2O_2. • Remarkable photo-catalytic degradation by doped bismuth selenide has been explained. • Scavenger tests show degradation of MG is mainly dominated by ·OH oxidation process. - Abstract: Bismuth selenide (Bi_2Se_3) and nickel (Ni) doped Bi_2Se_3 were prepared by a solvothermal approach to explore the photo-catalytic performance of the materials in degradation of malachite green (MG). The presence of nickel was confirmed by X-ray photoelectron spectroscopy (XPS) measurement in doped Bi_2Se_3. The results showed that the nickel doping played an important role in microstructure and photo-catalytic activity of the samples. Nickel doped Bi_2Se_3 sample exhibited higher photo-catalytic activity than that of the pure Bi_2Se_3 sample under visible-light irradiation. The photo-catalytic degradation followed first-order reaction kinetics. Fast degradation kinetics and complete (100% in 5 min of visible light irradiation) removal of MG was achieved by nickel doped Bi_2Se_3 in presence of hydrogen peroxide (H_2O_2) due to modification of band gap energies leading to suppression of photo-generated electron-hole recombination.

Reduced Graphene Oxide: Is it a promising catalyst for the electrochemistry of [UO2(CO3)3]4−/[UO2(CO3)3]5−?

International Nuclear Information System (INIS)

Guin, Saurav K.; Ambolikar, Arvind S.; Kamat, J.V.

2015-01-01

Highlights: • First report on aqueous electrochemistry of uranium on graphene materials. • Graphene(Nafion)/GC did not show applicability for the anionic analytes. • Electrochemically Reduced Graphene Oxide (ERGNO) was synthesised by cyclic voltammetry. • ERGNO catalysed the electrochemistry of [U VI O 2 (CO 3 ) 3 ] 4- /[U V O 2 (CO 3 ) 3 ] 5- . • Both the cathodic and anodic overpotentials of U(VI)/U(V) reaction decreased on ERGNO. - Abstract: The graphene has been emerging in the electrocatalysis and electroanalysis as the potent surface modifying agents for the working electrodes. However, the aqueous electrochemistry of the actinides on graphene (or graphene type materials) is yet unexplored. In this paper, the aqueous electrochemistry of [U VI O 2 (CO 3 ) 3 ] 4− /[U V O 2 (CO 3 ) 3 ] 5− redox couple was systematically investigated on electrochemically reduced graphene oxide (ERGNO) modified glassy carbon (GC) electrode in saturated Na 2 CO 3 solution (pH ∼12.3). This is the first report on aqueous actinide electrochemistry on graphene materials. The results showed that ERGNO could catalyse the redox chemistry of [U VI O 2 (CO 3 ) 3 ] 4− /[U V O 2 (CO 3 ) 3 ] 5− by reducing both the cathodic and anodic overpotentials compared to bare GC electrode. However, no enhancement in the peak current was observed on ERGNO electrode for the same reaction. Therefore, the present study introduces an appeal for a systematic investigation on the electrochemistry of the actinides at graphene materials to gear up their applications in nuclear technology

Methods of making copper selenium precursor compositions with a targeted copper selenide content and precursor compositions and thin films resulting therefrom

Science.gov (United States)

Curtis, Calvin J [Lakewood, CO; Miedaner, Alexander [Boulder, CO; van Hest, Marinus Franciscus Antonius Maria; Ginley, David S [Evergreen, CO; Leisch, Jennifer [Denver, CO; Taylor, Matthew [West Simsbury, CT; Stanbery, Billy J [Austin, TX

2011-09-20

Precursor compositions containing copper and selenium suitable for deposition on a substrate to form thin films suitable for semi-conductor applications. Methods of forming the precursor compositions using primary amine solvents and methods of forming the thin films wherein the selection of temperature and duration of heating controls the formation of a targeted species of copper selenide.

Synthesis, Molecular Structure, and Electrochemistry of 1-Ferrocenyl-1,2-dicarba-closo-dodecaboranes

Czech Academy of Sciences Publication Activity Database

Korotvička, A.; Šnajdr, I.; Štěpnička, P.; Císařová, I.; Janoušek, Zbyněk; Kotora, M.

-, č. 15 (2013), s. 2789-2798 ISSN 1434-1948 Grant - others:GA ČR(CZ) GAP207/11/0338; GAČR(CZ) GAP207/11/0705 Program:GA Institutional support: RVO:61388963 Keywords : carboranes * metallocenes * structure elucidation * electrochemistry * addition Subject RIV: CA - Inorganic Chemistry Impact factor: 2.965, year: 2013

Electrochemistry and microsystems

International Nuclear Information System (INIS)

Ehrfeld, Wolfgang

2003-01-01

Electrochemistry takes a key position in products and manufacturing processes of microtechnology, which has established a multi-billion dollar market with applications in information, entertainment, medical, automotive, telecom and many other technologies. In combination with microlithographic pattern generation electrochemical deposition processes are applied in manufacturing CDs and DVDs, nozzle plates for ink jet printers, read-write heads for hard magnetic disks and solder bumps for flip-chip technology. Three-dimensional microstructures with extremely high precision and aspect ratio are manufactured by means of LIGA technology, which combines deep lithography, electroforming and moulding process steps. Field assisted etching processes with ultra-short voltage pulses, anodization of silicon and field assisted ion exchange in glass have been successfully used for generating microstructures. Meanwhile, there are a huge number of microdevices, which utilize electrochemical phenomena. ISFETs and ion sensitive electrodes are standard components in the field of microsensors, microfuel cells will become high-performance power supply systems for mobile IT and entertainment products. In communication technology electrophoresis-based on electronic ink displays will become more and more important products. The most challenging development is dealing with so-called labs-on-a-chip which utilize electrochemical phenomena like electrophoresis, isoelectric focussing and electroosmosis to create a novel platform for ultra-miniaturized analytics in life sciences, medical diagnosis, environmental technologies and many other areas of modern development

Purines bearing phenanthroline or bipyridine ligands and their Ru II complexes in position 8 as model compounds for electrochemical DNA labeling - synthesis, crystal structure, electrochemistry, quantum calculations, cytostatic and antiviral activity

Czech Academy of Sciences Publication Activity Database

Vrábel, Milan; Hocek, Michal; Havran, Luděk; Fojta, Miroslav; Votruba, Ivan; Klepetářová, Blanka; Pohl, Radek; Rulíšek, Lubomír; Zendlová, Lucie; Hobza, Pavel; Shih, I.; Mabery, E.; Mackman, R.

-, č. 12 (2007), s. 1752-1769 ISSN 1434-1948 R&D Projects: GA ČR GA203/05/0043; GA ČR(CZ) GD203/05/H001; GA MŠk LC512; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50040507 Keywords : purines * Ru complexes * electrochemistry Subject RIV: CC - Organic Chemistry Impact factor: 2.597, year: 2007

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

Science.gov (United States)

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

2015-06-24

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

Control of accidental releases of hydrogen selenide in vented storage cabinets

Science.gov (United States)

Fthenakis, V. M.; Moskowitz, P. D.; Sproull, R. D.

1988-07-01

Highly toxic hydrogen selenide and hydrogen sulfide gases are used in the production of copper-indium-diselenide photovoltaic cells by reactive sputtering. In the event of an accident, these gases may be released to the atmosphere and pose hazards to public and occupational safety and health. This paper outlines an approach for designing systems for the control of these releases given the uncertainty in release conditions and lack of data on the chemical systems involved. Accidental releases of these gases in storage cabinets can be controlled by either a venturi and packed-bed scrubber and carbon adsorption bed, or containment scrubbing equipment followed by carbon adsorption. These systems can effectively reduce toxic gas emissions to levels needed to protect public health. The costs of these controls (˜0.012/Wp) are samll in comparison with current (˜6/Wp) and projected (˜I/Wp) production costs.

Understanding the mechanism of direct electrochemistry of mitochondria-modified electrodes from yeast, potato and bovine sources at carbon paper electrodes

International Nuclear Information System (INIS)

Giroud, Fabien; Nicolo, Tera A.; Koepke, Sara J.; Minteer, Shelley D.

2013-01-01

Although mitochondria have been used for bio-electrochemistry for over 5 years, little is known about their direct electrochemistry mechanism. This paper focuses on developing a better understanding of the electron transfer mechanism of mitochondria from three different organisms at carbon electrodes. Yeast, potato and bovine mitochondria have been successfully isolated and immobilized onto Toray paper electrodes via vapor deposited silica. Organelle-modified electrodes were first characterized using cyclic voltammetry. Similar electrochemical signals were obtained for all organisms. Direct electron transfer was observed when a metabolite of the Krebs cycle was present in the buffer solution. Control experiments based on the immobilization of two electron carriers contained in mitochondria, cytochrome c and a quinone (coenzyme Q 10 ), tend to show the electron transfer mechanism to the carbon material comes from the quinone pool of the organelles. As quinones are known to be pH-dependent, we further investigated the response of the electrochemical signal of the three isolated mitochondria and the two electron carriers separately. The half wave potentials obtained from the organelles appeared to be pH-dependent and their variations are comparable to coenzyme Q 10 rather than cytochrome c. Finally, extraction of both the cytochrome c and the quinone pool from intact mitochondria was performed to validate our hypothesis that direct electrochemistry of mitochondria happens via the quinone pool. Electrochemistry of immobilized quinone-depleted mitochondria validated the hypothesis that the mitochondria are communicating with the electrodes through the quinone pool

Synthesis, crystal structure, and magnetic properties of quaternary iron selenides: Ba{sub 2}FePnSe{sub 5} (Pn=Sb, Bi)

Energy Technology Data Exchange (ETDEWEB)

Wang, Jian; Greenfield, Joshua T.; Kovnir, Kirill

2016-10-15

Two new barium iron pnictide–selenides, Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5}, were synthesized by a high-temperature solid-state route and their crystal structures were determined using single crystal X-ray diffraction. Both compounds are isomorphic to the high pressure phase Ba{sub 3}FeS{sub 5} and crystallize in the orthorhombic space group Pnma (No. 62) with cell parameters of a=12.603(2)/12.619(2) Å, b=9.106(1)/9.183(1) Å, c=9.145(1)/9.123(1) Å and Z=4 for Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5}, respectively. According to differential scanning calorimetry, Ba{sub 2}FePnSe{sub 5} compounds exhibit high thermal stability and melt congruently at 1055(5) K (Pn=Sb) and 1105(5) K (Pn=Bi). Magnetic characterizations reveal strong antiferromagnetic nearest-neighbor interactions in both compounds resulting in an antiferromagnetic ordering at 58(1) K for Ba{sub 2}FeSbSe{sub 5} and 79(2) K for Ba{sub 2}FeBiSe{sub 5}. The magnetic interactions between Fe{sup 3+} centers, which are at least 6 Å apart from each other, are mediated by superexchange interactions. - Graphical abstract: In Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5} the magnetic interactions between Fe{sup 3+} centers, which are at least 6 Å apart from each other, are mediated by superexchange interactions. - Highlights: • New compounds Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5} have been synthesized. • The crystal structure was determined by single crystal X-ray diffraction. • Both compounds melt congruently at temperatures above 1000 K. • Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5} exhibit AFM ordering at 58 K (Sb) and 70 K (Bi). • Magnetic exchange between Fe{sup 3+} is mediated by either Se–Sb(Bi)–Se or Se–Ba–Se bridges.

7. International Frumkin Symposium. Basic electrochemistry for science and technology. Abstracts. Part 1

International Nuclear Information System (INIS)

2000-01-01

Modern tendencies of development of electrochemistry as in regions of fundamental investigations so in applied directions are presented. Basic themes of reports presented are: charge transport in condensed media, interface fenomena and electric properties at low soluble substances with electrolyte solutions, structure and properties of charged interfaces, transport in electrochemical systems, problems of bioelectrochemistry [ru

Polyamide–thallium selenide composite materials via temperature and pH controlled adsorption–diffusion method

Energy Technology Data Exchange (ETDEWEB)

Ivanauskas, Remigijus; Samardokas, Linas [Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu str. 19, Kaunas LT-50254 (Lithuania); Mikolajunas, Marius; Virzonis, Darius [Department of Technology, Kaunas University of Technology, Panevezys Faculty, Daukanto 12, 35212 Panevezys (Lithuania); Baltrusaitis, Jonas, E-mail: job314@lehigh.edu [Department of Chemical and Biomolecular Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States)

2014-10-30

Graphical abstract: Single phase polyamide–thallium selenide hybrid functional materials were synthesized for solar energy conversion. - Highlights: • Thallium selenide–polyamide composite materials surfaces synthesized. • Mixed phase composition confirmed by XRD. • Increased temperature resulted in a denser surface packing. • Urbach energies correlated with AFM showing decreased structural disorder. • Annealing in N{sub 2} at 100 °C yielded a single TlSe phase. - Abstract: Composite materials based on III–VI elements are promising in designing efficient photoelectronic devices, such as thin film organic–inorganic solar cells. In this work, TlSe composite materials were synthesized on a model polymer polyamide using temperature and pH controlled adsorption–diffusion method via (a) selenization followed by (b) the exposure to the group III metal (Tl) salt solution and their surface morphological, chemical and crystalline phase information was determined with particular focus on their corresponding structure–optical property relationship. XRD analysis yielded a complex crystalline phase distribution which correlated well with the optical and surface morphological properties measured. pH 11.3 and 80 °C yielded well defined, low structural disorder composite material surface. After annealing in N{sub 2} at 100 °C, polycrystalline PA-Tl{sub x}Se{sub y} composite materials yielded a single TlSe phase due to the enhanced diffusion and reaction of thallium ions into the polymer. The method described here can be used to synthesize variety of binary III–VI compounds diffused into the polymer at relatively low temperatures and low overall cost, thus providing for a flexible synthesis route for novel composite solar energy harvesting materials.

Growth and Low Temperature Transport Measurements of Pure and Doped Bismuth Selenide

DEFF Research Database (Denmark)

Mlack, Jerome Thomas

Se3, which is a strong spin orbit material and a topological insulator. I describe a synthesis technique and low-temperature transport measurements of nanostructures of Bi2Se3, that when annealed with palladium show evidence of superconductivity. The growth method is a catalyst-free atmospheric...... with palladium via annealing, the transport properties of the samples can be altered to exhibit superconductivity. Thin films of palladium are deposited on prefabricated Bi2Se3 nanodevices and annealed at temperatures in excess of 100 Celsius. We find that Bi2Se3 absorbs Pd under these conditions...... pressure vapor-solid growth. The growth method yields a variety of nanostructures, and materials analysis shows ordered structures of bismuth selenide in all cases. Low-temperature measurements of as-grown nanostructures indicate tunable carrier density in all samples. By doping the nanostructures...

Uncovering the intrinsic relationship of electrocatalysis and molecular electrochemistry for dissociative electron transfer to polychloroethanes at silver cathode

International Nuclear Information System (INIS)

Huang, Binbin; Zhu, Yuanyuan; Li, Jing; Zeng, Guangming; Lei, Chao

2017-01-01

Highlights: • Thermodynamics of dissociative electron transfer to C–Cl bonds at Ag are studied. • The catalyzed dissociative electron transfer theory was proposed for the first time. • The adsorption of organic chlorides onto Ag plays a key role for dechlorination. • The catalytic property of Ag is ascribed to the lower of intrinsic barrier energy. • The relationship of electrocatalysis and molecular electrochemistry is indicated. - Abstract: The relationship between electrocatalysis and molecular electrochemistry for the reductive dechlorination of organic chlorides has been a central topic for decades. Herein, we try to reveal the catalytic property of silver electrode by investigating the thermodynamics of dissociative electron transfer (DET) to C–Cl bonds of polychloroethanes (PCAs) on both inert (GC) and catalytic (Ag) electrodes. By extending the “sticky” DET model reported by Savéant, we show that the catalyzed DET model can well describe the activation-driving force relationships for the electrocatalytic dechlorination on Ag, where in addition to the possible ion-dipole interations, the adsorption of chlorinated species onto Ag surface, which is found to play a fundamental role in the electrocatalysis process in this study, is introduced in the new developed DET model. In this work, we firstly report that the catalytic property of Ag electrode characterizing with drastically postive shift of reduction potential is ascribed to the lower of intrinsic barrier free energy, rather than the activation free energy, for the reductive dechlorination. Moreover, the intrinsic relationship of electrocatalysis and molecular electrochemistry is clearly indicated and quantitatively developed. These results may provide new insights in uncovering both the nature of catalytic property of Ag and the relationship of electrocatalysis and molecular electrochemistry for PCAs and other halocarbons.

Laser Photolysis and Thermolysis of Organic Selenides and Tellurides for Chemical Gas-phase Deposition of Nanostructured Materials

Directory of Open Access Journals (Sweden)

Josef Pola

2009-03-01

Full Text Available Laser radiation-induced decomposition of gaseous organic selenides and tellurides resulting in chemical deposition of nanostructured materials on cold surfaces is reviewed with regard to the mechanism of the gas-phase decomposition and properties of the deposited materials. The laser photolysis and laser thermolysis of the Se and Te precursors leading to chalcogen deposition can also serve as a useful approach to nanostructured chalcogen composites and IVA group (Si, Ge, Sn element chalcogenides provided that it is carried out simultaneously with laser photolysis or thermolysis of polymer and IVA group element precursor.

Self-standing nanoribbons of antimony selenide and antimony sulfide with well-defined size and band gap

International Nuclear Information System (INIS)

Vadapoo, Rajasekarakumar; Krishnan, Sridevi; Yilmaz, Hulusi; Marin, Carlos

2011-01-01

Sub-10 nm semiconducting nanostructures are crucial for the realization of nanoscale devices. Fabrication of nanostructures at this scale with homogeneous properties is challenging. Using ab initio calculations, we show that self-standing ribbons of antimony selenide and antimony sulfide of width 1.1 nm exhibit well-defined bandgaps of 1.66 and 2.16 eV, respectively. Molecular dynamics studies show that these ribbons are stable at 500 K. The one-dimensional (1D) heterostructure of these nanoribbons (Sb 2 Se 3 /Sb 2 S 3 ) along the [001] direction shows a straddling type behavior.

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

International Nuclear Information System (INIS)

Oh, Seung Mi; Lee, Eunsil; Adpakpang, Kanyaporn; Patil, Sharad B.; Park, Mi Jin; Lim, Young Soo; Lee, Kyu Hyoung; Kim, Jong-Young; Hwang, Seong-Ju

2015-01-01

Graphical abstract: Display Omitted -- Highlights: • In 4 Se 2.85 @graphene nanocomposite is easily prepared by high energy mechanical milling process. • The bond covalency of In 4 Se 2.85 is notably changed upon the composite formation with graphene. • In 4 Se 2.85 @graphene nanocomposite shows promising anode performance for lithium ion battery. -- Abstract: Evolution of the chemical bonding nature and electrochemical activity of indium selenide upon the composite formation with carbon species is systematically investigated. Nanocomposites of In 4 Se 2.85 @graphene and In 4 Se 2.85 @carbon-black are synthesized via a solid state reaction between In and Se elements, and the following high energy mechanical milling of In 4 Se 2.85 with graphene and carbon-black, respectively. The high energy mechanical milling (HEMM) of In 4 Se 2.85 with carbon species gives rise to a decrease of particle size with a significant depression of the crystallinity of In 4 Se 2.85 phase. In contrast to the composite formation with carbon-black, that with graphene induces a notable decrease of (In−Se) bond covalency, underscoring significant chemical interaction between graphene and In 4 Se 2.85 . Both the nanocomposites of In 4 Se 2.85 @graphene and In 4 Se 2.85 @carbon-black show much better anode performance for lithium ion batteries with larger discharge capacity and better cyclability than does the pristine In 4 Se 2.85 material, indicating the beneficial effect of composite formation on the electrochemical activity of indium selenide. Between the present nanocomposites, the electrode performance of the In 4 Se 2.85 @graphene nanocomposite is superior to that of the In 4 Se 2.85 @carbon-black nanocomposite, which is attributable to the weakening of (In−Se) bonds upon the composite formation with graphene as well as to the better mixing between In 4 Se 2.85 and graphene. The present study clearly demonstrates that the composite formation with graphene has strong influence

Electron exchange between neutral and ionized impurity iron centers in vitreous arsenic selenide

Energy Technology Data Exchange (ETDEWEB)

Marchenko, A. V. [Herzen State Pedagogical University of Russia (Russian Federation); Terukov, E. I. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Egorova, A. Yu. [St.-Petersburg Mining University (Russian Federation); Kiselev, V. S.; Seregin, P. P., E-mail: ppseregin@mail.ru [Herzen State Pedagogical University of Russia (Russian Federation)

2017-04-15

Impurity iron atoms in vitreous arsenic-selenide As{sub 2}Se{sub 3} films modified by iron form one-electron donor centers with an ionization energy of 0.24 (3) eV (the energy is counted from the conduction-band bottom). The Fermi level is shifted with an increase in the iron concentration from the mid-gap to the donorlevel position of iron due to the filling of one-electron states of the acceptor type lying below the Fermi level. At an iron concentration of ≥3 at %, the electron-exchange process is observed between neutral and ionized iron centers resulting in a change both in the electron density and in the tensor of the electric-field gradient at iron-atom nuclei with increasing temperature above 350 K.

Molybdenum, molybdenum oxides, and their electrochemistry.

Science.gov (United States)

Saji, Viswanathan S; Lee, Chi-Woo

2012-07-01

The electrochemical behaviors of molybdenum and its oxides, both in bulk and thin film dimensions, are critical because of their widespread applications in steels, electrocatalysts, electrochromic materials, batteries, sensors, and solar cells. An important area of current interest is electrodeposited CIGS-based solar cells where a molybdenum/glass electrode forms the back contact. Surprisingly, the basic electrochemistry of molybdenum and its oxides has not been reviewed with due attention. In this Review, we assess the scattered information. The potential and pH dependent active, passive, and transpassive behaviors of molybdenum in aqueous media are explained. The major surface oxide species observed, reversible redox transitions of the surface oxides, pseudocapacitance and catalytic reduction are discussed along with carefully conducted experimental results on a typical molybdenum glass back contact employed in CIGS-based solar cells. The applications of molybdenum oxides and the electrodeposition of molybdenum are briefly reviewed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemistry-based Battery Modeling for Prognostics

Science.gov (United States)

Daigle, Matthew J.; Kulkarni, Chetan Shrikant

2013-01-01

Batteries are used in a wide variety of applications. In recent years, they have become popular as a source of power for electric vehicles such as cars, unmanned aerial vehicles, and commericial passenger aircraft. In such application domains, it becomes crucial to both monitor battery health and performance and to predict end of discharge (EOD) and end of useful life (EOL) events. To implement such technologies, it is crucial to understand how batteries work and to capture that knowledge in the form of models that can be used by monitoring, diagnosis, and prognosis algorithms. In this work, we develop electrochemistry-based models of lithium-ion batteries that capture the significant electrochemical processes, are computationally efficient, capture the effects of aging, and are of suitable accuracy for reliable EOD prediction in a variety of usage profiles. This paper reports on the progress of such a model, with results demonstrating the model validity and accurate EOD predictions.

Transition-Metal-Free Diarylannulated Sulfide and Selenide Construction via Radical/Anion-Mediated Sulfur-Iodine and Selenium-Iodine Exchange.

Science.gov (United States)

Wang, Ming; Fan, Qiaoling; Jiang, Xuefeng

2016-11-04

A facile, straightforward protocol was established for diarylannulated sulfide and selenide construction through S-I and Se-I exchange without transition metal assistance. Elemental sulfur and selenium served as the chalcogen source. Diarylannulated sulfides were systematically achieved from a five- to eight-membered ring. A trisulfur radical anion was demonstrated as the initiator for this radical process via electron paramagnetic resonance (EPR) study. OFET molecules [1]benzothieno[3,2-b][1]benzothiophene (BTBT) and [1]benzothieno[3,2-b][1]benzoselenophene (BTBS) were efficiently established.

New quaternary thallium indium germanium selenide TlInGe2Se6: Crystal and electronic structure

Science.gov (United States)

Khyzhun, O. Y.; Parasyuk, O. V.; Tsisar, O. V.; Piskach, L. V.; Myronchuk, G. L.; Levytskyy, V. O.; Babizhetskyy, V. S.

2017-10-01

Crystal structure of a novel quaternary thallium indium germanium selenide TlInGe2Se6 was investigated by means of powder X-ray diffraction method. It was determined that the compound crystallizes in the trigonal space group R3 with the unit cell parameters a = 10.1798(2) Å, c = 9.2872(3) Å. The relationship with similar structures was discussed. The as-synthesized TlInGe2Se6 ingot was tested with X-ray photoelectron spectroscopy (XPS) and X-ray emission spectroscopy (XES). In particular, the XPS valence-band and core-level spectra were recorded for initial and Ar+ ion-bombarded surfaces of the sample under consideration. The XPS data allow for statement that the TlInGe2Se6 surface is rigid with respect to Ar+ ion-bombardment. Particularly, Ar+ ion-bombardment (3.0 keV, 5 min duration, ion current density fixed at 14 μA/cm2) did not cause substantial modifications of stoichiometry in topmost surface layers. Furthermore, comparison on a common energy scale of the XES Se Kβ2 and Ge Kβ2 bands and the XPS valence-band spectrum reveals that the principal contributions of the Se 4p and Ge 4p states occur in the upper and central portions of the valence band of TlInGe2Se6, respectively, with also their substantial contributions in other portions of the band. The bandgap energy of TlInGe2Se6 at the level of αg=103 cm-1 is equal to 2.38 eV at room temperature.

Hydrogenated graphenes by birch reduction: influence of electron and proton sources on hydrogenation efficiency, magnetism, and electrochemistry

Czech Academy of Sciences Publication Activity Database

Eng, A.Y.S.; Sofer, Z.; Huber, Š.; Bouša, D.; Maryško, Miroslav; Pumera, M.

2015-01-01

Roč. 21, č. 7 (2015), 16828-16838 ISSN 0947-6539 Institutional support: RVO:68378271 Keywords : hydrogenated graphenes * birch reduction * magnetism * electrochemistry * hydrogenation efficiency Subject RIV: CA - Inorganic Chemistry Impact factor: 5.771, year: 2015

Application of ultrasound in electrochemistry. An overview of mechanisms and design of experimental arrangement

Czech Academy of Sciences Publication Activity Database

Klíma, Jiří

2011-01-01

Roč. 51, č. 2 (2011), s. 202-209 ISSN 0041-624X R&D Projects: GA MŠk LC510; GA MŠk 1P05OC074 Institutional research plan: CEZ:AV0Z40400503 Keywords : sonoelectrochemistry * mechanism of sonochemical effect * microjets Subject RIV: CG - Electrochemistry Impact factor: 1.838, year: 2011

Density functional theory study of inter-layer coupling in bulk tin selenide

Science.gov (United States)

Song, Hong-Yue; Lü, Jing-Tao

2018-03-01

We study the inter-layer coupling in bulk tin selenide (SnSe) through density functional theory based calculations. Different approximations for the exchange-correlation functionals and the van der Waals interaction are employed. By performing comparison with graphite, MoS2 and black phosphorus, we analyze the inter-layer coupling from different points of view, including the binding energy, the low frequency inter-layer optical phonons, and the inter-layer charge transfer. We find that, there is a strong charge transfer between layers of SnSe, resulting in the strongest inter-layer coupling. Moreover, the charge transfer renders the inter-layer coupling in SnSe not of van der Waals type. Mechanical exfoliation has been used to fabricate mono- or few-layer graphene, MoS2 and black phosphorus. But, our results show that it may be difficult to apply similar technique to SnSe.

Solar Light Responsive Photocatalytic Activity of Reduced Graphene Oxide-Zinc Selenide Nanocomposite

Science.gov (United States)

Chakraborty, Koushik; Ibrahim, Sk; Das, Poulomi; Ghosh, Surajit; Pal, Tanusri

2017-10-01

Solution processable reduced graphene oxide-zinc selenide (RGO-ZnSe) nanocomposite has been successfully synthesized by an easy one-pot single-step solvothermal reaction. The RGO-ZnSe composite was characterized structurally and morphologically by the study of XRD analysis, SEM and TEM imaging. Reduction in graphene oxide was confirmed by FTIR spectroscopy analysis. Photocatalytic efficiency of RGO-ZnSe composite was investigated toward the degradation of Rhodamine B under solar light irradiation. Our study indicates that the RGO-ZnSe composite is catalytically more active compared to the controlled-ZnSe under the solar light illumination. Here, RGO plays an important role for photoinduced charge separation and subsequently hinders the electron-hole recombination probability that consequently enhances photocatalytic degradation efficiency. We expect that this type of RGO-based optoelectronics materials opens up a new avenue in the field of photocatalytic degradation of different organic water pollutants.

On-line probe for fast electrochemistry/electrospray mass spectrometry. Investigation of polycyclic aromatic hydrocarbons.

Science.gov (United States)

Xu, X; Lu, W; Cole, R B

1996-12-01

A newly invented probe accessory for fast electrochemistry/electrospray mass spectrometry (EC/ESMS) is presented and evaluated. The device features a low-volume, three-electrode electrochemical cell which has been designed with a minimum distance between the working electrode and the "Taylor cone" inherent to the electrospray process. This configuration limits the time between electrochemical generation of ions and mass spectrometric analysis to an absolute minimum. A fused-silica layer insulates the microcylinder working electrode from the sample solution until immediately prior to the electrospray region, postponing electrode processes until the last moment. The same fused-silica layer insulates the working electrode from the surrounding auxiliary electrode, a stainless steel capillary that also serves as the electrospray capillary. The performance and capabilities of the novel electrochemistry/electrospray mass spectrometry system have been evaluated using polycyclic aromatic hydrocarbons (PAHs) as test analytes. In the positive ion EC/ESMS mode, oxidized forms (one-electron removal) of PAHs are produced in high yield. The ability to analyze reaction products appearing subsequent to the initial oxidation is also demonstrated.

Fabrication of graphene–platinum nanocomposite for the direct electrochemistry and electrocatalysis of myoglobin

Energy Technology Data Exchange (ETDEWEB)

Sun, Wei, E-mail: swyy26@hotmail.com [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China); College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Li, Linfang [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Lei, Bingxin [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China); Li, Tongtong; Ju, Xiaomei; Wang, Xiuzheng; Li, Guangjiu [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Sun, Zhenfan [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China)

2013-05-01

In this paper a platinum (Pt) nanoparticle decorated graphene (GR) nanosheet was synthesized and used for the investigation on direct electrochemistry of myoglobin (Mb). By integrating GR–Pt nanocomposite with Mb on the surface of carbon ionic liquid electrode (CILE), a new electrochemical biosensor was fabricated. UV-Vis absorption and FT-IR spectra indicated that Mb remained its native structure in the nanocomposite film. Electrochemical behaviors of Nafion/Mb–GR–Pt/CILE were investigated with a pair of well-defined redox peak appeared, which indicated that direct electron transfer of Mb was realized on the underlying electrode with the usage of the GR–Pt nanocomposite. The fabricated electrode showed good electrocatalytic activity to the reduction of trichloroacetic acid in the linear range from 0.9 to 9.0 mmol/L with the detection limit as 0.32 mmol/L (3σ), which showed potential application for fabricating novel electrochemical biosensors and bioelectronic devices. - Highlights: ► The GR–Pt nanocomposite was synthesized and employed for the fabrication of electrochemical biosensor. ► Direct electrochemistry of Mb in the nanocomposite was realized. ► The prepared biosensor exhibited excellent electrochemical response to the reduction of TCA.

Integration of electrochemistry in micro-total analysis systems for biochemical assays: recent developments.

Science.gov (United States)

Xu, Xiaoli; Zhang, Song; Chen, Hui; Kong, Jilie

2009-11-15

Micro-total analysis systems (microTAS) integrate different analytical operations like sample preparation, separation and detection into a single microfabricated device. With the outstanding advantages of low cost, satisfactory analytical efficiency and flexibility in design, highly integrated and miniaturized devices from the concept of microTAS have gained widespread applications, especially in biochemical assays. Electrochemistry is shown to be quite compatible with microanalytical systems for biochemical assays, because of its attractive merits such as simplicity, rapidity, high sensitivity, reduced power consumption, and sample/reagent economy. This review presents recent developments in the integration of electrochemistry in microdevices for biochemical assays. Ingenious microelectrode design and fabrication methods, and versatility of electrochemical techniques are involved. Practical applications of such integrated microsystem in biochemical assays are focused on in situ analysis, point-of-care testing and portable devices. Electrochemical techniques are apparently suited to microsystems, since easy microfabrication of electrochemical elements and a high degree of integration with multi-analytical functions can be achieved at low cost. Such integrated microsystems will play an increasingly important role for analysis of small volume biochemical samples. Work is in progress toward new microdevice design and applications.

Phase diagram of (Li(1-x)Fe(x))OHFeSe: a bridge between iron selenide and arsenide superconductors.

Science.gov (United States)

Dong, Xiaoli; Zhou, Huaxue; Yang, Huaixin; Yuan, Jie; Jin, Kui; Zhou, Fang; Yuan, Dongna; Wei, Linlin; Li, Jianqi; Wang, Xinqiang; Zhang, Guangming; Zhao, Zhongxian

2015-01-14

Previous experimental results have shown important differences between iron selenide and arsenide superconductors which seem to suggest that the high-temperature superconductivity in these two subgroups of iron-based families may arise from different electronic ground states. Here we report the complete phase diagram of a newly synthesized superconducting (SC) system, (Li1-xFex)OHFeSe, with a structure similar to that of FeAs-based superconductors. In the non-SC samples, an antiferromagnetic (AFM) spin-density-wave (SDW) transition occurs at ∼127 K. This is the first example to demonstrate such an SDW phase in an FeSe-based superconductor system. Transmission electron microscopy shows that a well-known √5×√5 iron vacancy ordered state, resulting in an AFM order at ∼500 K in AyFe2-xSe2 (A = metal ions) superconductor systems, is absent in both non-SC and SC samples, but a unique superstructure with a modulation wave vector q = (1)/2(1,1,0), identical to that seen in the SC phase of KyFe2-xSe2, is dominant in the optimal SC sample (with an SC transition temperature Tc = 40 K). Hence, we conclude that the high-Tc superconductivity in (Li1-xFex)OHFeSe stems from the similarly weak AFM fluctuations as FeAs-based superconductors, suggesting a universal physical picture for both iron selenide and arsenide superconductors.

The Effects of Problem-Based Learning (PBL) on the Academic Achievement of Students Studying "Electrochemistry"

Science.gov (United States)

Günter, Tugçe; Alpat, Sibel Kilinç

2017-01-01

This study investigates the effects of problem-based learning (PBL) on students' academic achievements in studying "Electrochemistry" within a course on Analytical Chemistry. The research was of a pretest-posttest control group quasi-experimental design and it was conducted with second year students in the Chemistry Teaching Program at…

Investigating Phase Transform Behavior in Indium Selenide Based RAM and Its Validation as a Memory Element

Directory of Open Access Journals (Sweden)

Swapnil Sourav

2016-01-01

Full Text Available Phase transform properties of Indium Selenide (In2Se3 based Random Access Memory (RAM have been explored in this paper. Phase change random access memory (PCRAM is an attractive solid-state nonvolatile memory that possesses potential to meet various current technology demands of memory design. Already reported PCRAM models are mainly based upon Germanium-Antimony-Tellurium (Ge2Sb2Te5 or GST materials as their prime constituents. However, PCRAM using GST material lacks some important memory attributes required for memory elements such as larger resistance margin between the highly resistive amorphous and highly conductive crystalline states in phase change materials. This paper investigates various electrical and compositional properties of the Indium Selenide (In2Se3 material and also draws comparison with its counterpart mainly focusing on phase transform properties. To achieve this goal, a SPICE model of In2Se3 based PCRAM model has been reported in this work. The reported model has been also validated to act as a memory cell by associating it with a read/write circuit proposed in this work. Simulation results demonstrate impressive retentivity and low power consumption by requiring a set pulse of 208 μA for a duration of 100 μs to set the PCRAM in crystalline state. Similarly, a reset pulse of 11.7 μA for a duration of 20 ns can set the PCRAM in amorphous state. Modeling of In2Se3 based PCRAM has been done in Verilog-A and simulation results have been extensively verified using SPICE simulator.

Synthesis of Cation and Water Free Cryptomelane Type OMS-2 Cathode Materials: The Impact of Tunnel Water on Electrochemistry

Energy Technology Data Exchange (ETDEWEB)

Poyraz, Altug S.; Huang, Jianping; Zhang, Bingjie; Marschilok, Amy C.; Takeuchi, Kenneth J.; Takeuchi, Esther S.

2017-01-01

Cryptomelane type manganese dioxides (α-MnO₂, OMS-2) are interesting potential cathode materials due to the ability of their one dimensional (1D) tunnels to reversibly host various cations including Li⁺and an accessible stable 3+/4+ redox couple. Here, we synthesized metal cation free OMS-2 materials where the tunnels were occupied by only water and hydronium ions. Water was subsequently removed from the tunnels. Cation free OMS-2 and Dry-OMS-2 were used as cathodes in Li based batteries to investigate the role of tunnel water on their electrochemistry. The initial discharge capacity was higher for Dry-OMS-2 (252 mAh/g) compared to OMS-2 (194 mAh/g), however, after 100 cycles Dry-OMS-2 and OMS-2 delivered 137 mAh/g and 134 mAh/g, respectively. Li⁺ion diffusion was more facile for Dry-OMS as evidenced by rate capability, at 400 mA/g. Dry-OMS-2 delivered 135mAh/g whereas OMS-2 delivered ~115 mAh/g. This first report of the impact of tunnel water on the electrochemistry of OMS-2 type materials demonstrates that the presence of tunnel water in OMS-2 type materials negatively impacts the electrochemistry.

Repair of model compounds of photoinduced lesions in DNA. Electrochemical approaches

International Nuclear Information System (INIS)

Boussicault, F.

2006-09-01

The goal of this work is to better understand the repair mechanism of photoinduced lesions in DNA (cyclobutane dimers and pyrimidine (6-4) pyrimidone adducts) by photolyase redox enzymes, using tools and concepts of molecular electrochemistry. Thanks to the study of model compounds of cyclobutane lesions by cyclic voltametry, we have been able to mimic the key step of the enzymatic repair (dissociative electron transfer) and to monitor the repair of model compounds by Escherichia coli DNA photolyase. From these results, we have discussed the repair mechanism, especially the stepwise or concerted character of the process. Repair mechanism of (6-4) adducts is not known now, but a possible pathway implies an electron transfer coupled to the cleavage of two bonds in the closed form of the lesions (oxetanes). Voltammetric study of reduction and oxidation of model oxetanes and their repair by E. coli DNA photolyase gave some experimental evidence confirming the proposed mechanism and allowing a better understanding of it. (author)

Effects of Jigsaw and Animation Techniques on Students' Understanding of Concepts and Subjects in Electrochemistry

Science.gov (United States)

Doymus, Kemal; Karacop, Ataman; Simsek, Umit

2010-01-01

This study investigated the effect of jigsaw cooperative learning and animation versus traditional teaching methods on students' understanding of electrochemistry in a first-year general chemistry course. This study was carried out in three different classes in the department of primary science education during the 2007-2008 academic year. The…

The role of isomorphous substitutions in natural selenides belonging to the pyrite group

International Nuclear Information System (INIS)

Bindi, Luca; Cipriani, Curzio; Pratesi, Giovanni; Trosti-Ferroni, Renza

2008-01-01

The present paper reports chemical and structural data of selenide minerals belonging to the pyrite group. Eighteen samples of minerals in this group with variable chemical composition (7 samples of penroseite, NiSe 2 ; 10 samples of krutaite, CuSe 2 ; 1 sample of trogtalite, CoSe 2 ) were studied by means of X-ray single-crystal diffraction and electron microprobe. On the basis of information gained from the chemical characterization, we can conclude that a complete solid solution between NiSe 2 and CuSe 2 exists in nature with the absence of pure end-members. Although verified only for the Ni-rich members, we also infer a solid solution between NiSe 2 and CoSe 2 . The unit-cell parameters were modeled using a multiple regression method as a function of the Co, Ni, and Cu contents

The lattice dynamical studies of rare earth compounds: electron-phonon interactions

International Nuclear Information System (INIS)

Jha, Prafulla K.; Sanyal, Sankar P.; Singh, R.K.

2002-01-01

During the last two decades chalcogenides and pnictides of rare earth (RE) atoms have drawn considerable attention of the solid state physicists because of their peculiar electronic, magnetic, optical and phonon properties. Some of these compounds e.g. sulphides and selenides of cerium (Ce), samarium (Sm), yttrium (Y), ytterbium (Yb), europium (Eu) and thulium (Tm) and their alloys show nonintegral valence (between 2 and 3), arising due to f-d electron hybridization at ambient temperature and pressure. The rare earth mixed valence compounds (MVC) reviewed in this article crystallize in simple cubic structure. Most of these compounds show the existence of strong electron-phonon coupling at half way to the zone boundary. This fact manifests itself through softening of the longitudinal acoustic mode, negative value of elastic constant C 12 etc. The purpose of this contribution is to review some of the recent activities in the fields of lattice dynamics and allied properties of rare earth compounds. The present article is primarily devoted to review the effect of electron-phonon interactions on the dynamical properties of rare earth compounds by using the lattice dynamical model theories based on charged density deformations and long-range many body forces. While the long range charge transfer effect arises due to f-d hybridization of nearly degenerate 4f-5d bands of rare earth ions, the density deformation comes into the picture of breathing motion of electron shells. These effects of charge transfer and charge density deformation when considered in the lattice dynamical models namely the three body force rigid ion model (TRM) and breathing shell model (BSM) are quite successful in explaining the phonon anomalies in these compounds and undoubtedly unraveled many important physical process governing the phonon anomalies in rare earth compounds

Forensic analyses of explosion debris from the January 2, 1992 Pd/D2O electrochemistry incident at SRI International

International Nuclear Information System (INIS)

Andresen, B.; Whipple, R.; Vandervoort, D.; Grant, P.

1992-01-01

The January 2, 1992 explosion in an electrochemistry laboratory at SRI International (SRI) resulted in the death of scientist Andrew Riley, and gained some notoriety due to its association with experimental work in the controversial field of cold fusion research. Selected components of explosion debris were subjected to forensic analyses at LLNL to elucidate potential causes of, or contributing factors to, the explosion. Interrogation of the debris by LLNL encompassed nuclear, chemical, physical, and materials investigations. Nuclear studies for the determination of tritium and neutron-activation products in stainless steel and brass were negative. No evidence of signature species indicative of orthodox nuclear events was detected. The inorganic and particulate analyses were likewise negative with respect to residues of unexpected chemical species. Such target compounds included conventional explosives, accelerants, propellants, or any exceptional industrial chemicals. The GC-MS analyses of trace organic components in the explosion debris provided perhaps the most interesting results obtained at LLNL. Although no evidence of organic explosives, oxidizers, or other unusual compounds was detected, the presence of a hydrocarbon oil in the interior of the electrochemical cell was established. It is likely that its source was lubricating fluid from the machining of the metal cell components. If residues of organic oils are present during electrolysis experiments, the potential exists for an explosive reaction in the increasingly enriched oxygen atmosphere within the headspace of a metal cell

A Historical Analysis of the Daniell Cell and Electrochemistry Teaching in French and Tunisian Textbooks

Science.gov (United States)

Boulabiar, Ahlem; Bouraoui, Kamel; Chastrette, Maurice; Abderrabba, Manef

2004-01-01

The condition in which the Daniell Cell was historically constructed is examined and the evolution of its presentation in French and Tunisian chemistry textbooks is analyzed. Based on the studies, several innovations to facilitate the teaching of the cell, and more generally, the teaching of electrochemistry and of ionic conduction are proposed.

Selective growth of gold onto copper indium sulfide selenide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Witt, Elena; Parisi, Juergen; Kolny-Olesiak, Joanna [Oldenburg Univ. (Germany). Inst. of Physics, Energy and Semiconductor Research

2013-05-15

Hybrid nanostructures are interesting materials for numerous applications in chemistry, physics, and biology, due to their novel properties and multiple functionalities. Here, we present a synthesis of metal-semiconductor hybrid nanostructures composed of nontoxic I-III-VI semiconductor nanoparticles and gold. Copper indium sulfide selenide (CuInSSe) nanocrystals with zinc blende structure and trigonal pyramidal shape, capped with dodecanethiol, serve as an original semiconductor part of a new hybrid nanostructure. Metallic gold nanocrystals selectively grow onto vertexes of these CuInSSe pyramids. The hybrid nanostructures were studied by transmission electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, and UV-Vis-absorption spectroscopy, which allowed us conclusions about their growth mechanism. Hybrid nanocrystals are generated by replacement of a sacrificial domain in the CuInSSe part. At the same time, small selenium nanocrystals form that stay attached to the remaining CuInSSe/Au particles. Additionally, we compare the synthesis and properties of CuInSSe-based hybrid nanostructures with those of copper indium disulfide (CuInS{sub 2}). CuInS{sub 2}/Au nanostructures grow by a different mechanism (surface growth) and do not show any selectivity. (orig.)

Transport properties of Cu-doped bismuth selenide single crystals at high magnetic fields up to 60 Tesla: Shubnikov-de Haas oscillations and π-Berry phase

Science.gov (United States)

Romanova, Taisiia A.; Knyazev, Dmitry A.; Wang, Zhaosheng; Sadakov, Andrey V.; Prudkoglyad, Valery A.

2018-05-01

We report Shubnikov-de Haas (SdH) and Hall oscillations in Cu-doped high quality bismuth selenide single crystals. To increase the accuracy of Berry phase determination by means of the of the SdH oscillations phase analysis we present a study of n-type samples with bulk carrier density n ∼1019 -1020cm-3 at high magnetic field up to 60 Tesla. In particular, Landau level fan diagram starting from the value of the Landau index N = 4 was plotted. Thus, from our data we found π-Berry phase that directly indicates the Dirac nature of the carriers in three-dimensional topological insulator (3D TI) based on Cu-doped bismuth selenide. We argued that in our samples the magnetotransport is determined by a general group of carriers that exhibit quasi-two-dimensional (2D) behaviour and are characterized by topological π-Berry phase. Along with the main contribution to the conductivity the presence of a small group of bulk carriers was registered. For 3D-pocket Berry phase was identified as zero, which is a characteristic of trivial metallic states.

Common Principles of Molecular Electronics and Nanoscale Electrochemistry.

Science.gov (United States)

Bueno, Paulo Roberto

2018-05-24

The merging of nanoscale electronics and electrochemistry can potentially modernize the way electronic devices are currently engineered or constructed. It is well known that the greatest challenges will involve not only miniaturizing and improving the performance of mobile devices, but also manufacturing reliable electrical vehicles, and engineering more efficient solar panels and energy storage systems. These are just a few examples of how technological innovation is dependent on both electrochemical and electronic elements. This paper offers a conceptual discussion of this central topic, with particular focus on the impact that uniting physical and chemical concepts at a nanoscale could have on the future development of electroanalytical devices. The specific example to which this article refers pertains to molecular diagnostics, i.e., devices that employ physical and electrochemical concepts to diagnose diseases.

Selenium electrochemistry. Applications in the nuclear fuel cycle

Energy Technology Data Exchange (ETDEWEB)

Maslennikov, A.; Peretroukhine, V. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Physical Chemistry; David, F. [Centre National de la Recherche Scientifique (CNRS), 91 - Orsay (France); Lecomte, M. [CEA Centre d' Etudes de la Valle du Rhone, 30 - Marcoule (France). Direction du Cycle du Combustible

1999-07-01

Modern state of selenium electrochemistry is reviewed in respect of the application of electrochemical methods for the study of the behavior of this element and its quantitative analysis in the solutions of nuclear fuel cycle. The review includes the data on the redox potentials of Se in aqueous solutions, and the data on Se redox reactions, occurring at mercury and solid electrodes. Analysis of the available literature data shows that the inverse stripping voltammetry technique for trace Se concentration and determination seems to be the most promising in application for the Se determination in PUREX solutions and in radioactive wastes. The adaptation of the ISV technique for the trace Se concentration and determination in the solutions of the nuclear fuel cycle is indicated as the most prospective goal of the future experimental study. (author)

Phase I and phase II reductive metabolism simulation of nitro aromatic xenobiotics with electrochemistry coupled with high resolution mass spectrometry.

Science.gov (United States)

Bussy, Ugo; Chung-Davidson, Yu-Wen; Li, Ke; Li, Weiming

2014-11-01

Electrochemistry combined with (liquid chromatography) high resolution mass spectrometry was used to simulate the general reductive metabolism of three biologically important nitro aromatic molecules: 3-trifluoromethyl-4-nitrophenol (TFM), niclosamide, and nilutamide. TFM is a pesticide used in the Laurential Great Lakes while niclosamide and nilutamide are used in cancer therapy. At first, a flow-through electrochemical cell was directly connected to a high resolution mass spectrometer to evaluate the ability of electrochemistry to produce the main reduction metabolites of nitro aromatic, nitroso, hydroxylamine, and amine functional groups. Electrochemical experiments were then carried out at a constant potential of -2.5 V before analysis of the reduction products by LC-HRMS, which confirmed the presence of the nitroso, hydroxylamine, and amine species as well as dimers. Dimer identification illustrates the reactivity of the nitroso species with amine and hydroxylamine species. To investigate xenobiotic metabolism, the reactivity of nitroso species to biomolecules was also examined. Binding of the nitroso metabolite to glutathione was demonstrated by the observation of adducts by LC-ESI(+)-HRMS and the characteristics of their MSMS fragmentation. In conclusion, electrochemistry produces the main reductive metabolites of nitro aromatics and supports the observation of nitroso reactivity through dimer or glutathione adduct formation.

The role of isomorphous substitutions in natural selenides belonging to the pyrite group

Energy Technology Data Exchange (ETDEWEB)

Bindi, Luca [Museo di Storia Naturale, sez. di Mineralogia e Litologia, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy)], E-mail: luca.bindi@unifi.it; Cipriani, Curzio [Museo di Storia Naturale, sez. di Mineralogia e Litologia, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy); Pratesi, Giovanni [Museo di Storia Naturale, sez. di Mineralogia e Litologia, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy); Dipartimento di Scienze della Terra, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy); Trosti-Ferroni, Renza [Dipartimento di Scienze della Terra, Universita degli Studi di Firenze, via La Pira 4, I-50121 Firenze (Italy)

2008-07-14

The present paper reports chemical and structural data of selenide minerals belonging to the pyrite group. Eighteen samples of minerals in this group with variable chemical composition (7 samples of penroseite, NiSe{sub 2}; 10 samples of krutaite, CuSe{sub 2}; 1 sample of trogtalite, CoSe{sub 2}) were studied by means of X-ray single-crystal diffraction and electron microprobe. On the basis of information gained from the chemical characterization, we can conclude that a complete solid solution between NiSe{sub 2} and CuSe{sub 2} exists in nature with the absence of pure end-members. Although verified only for the Ni-rich members, we also infer a solid solution between NiSe{sub 2} and CoSe{sub 2}. The unit-cell parameters were modeled using a multiple regression method as a function of the Co, Ni, and Cu contents.

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

International Nuclear Information System (INIS)

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

2016-01-01

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

Isoflurane as a solvent for electrochemistry. Electrooxidation study of icosahedral carborane anions in four different solvents

Czech Academy of Sciences Publication Activity Database

Wahab, Abdul; Kvapilová, Hana; Klíma, Jiří; Michl, Josef; Ludvík, Jiří

2013-01-01

Roč. 689, JAN 2013 (2013), s. 257-261 ISSN 1572-6657 R&D Projects: GA MŠk ME09002; GA ČR GC203/09/J058 Institutional support: RVO:61388955 ; RVO:61388963 Keywords : isoflurane * relative permitivity * icosahedral carborane anions Subject RIV: CG - Electrochemistry Impact factor: 2.871, year: 2013

A computationally efficient implementation of a full and reduced-order electrochemistry-based model for Li-Ion batteries

NARCIS (Netherlands)

Xia, L.; Najafi, E.; Li, Z.; Bergveld, H.J.; Donkers, M.C.F.

2017-01-01

Lithium-ion batteries are commonly employed in various applications owing to high energy density and long service life. Lithium-ion battery models are used for analysing batteries and enabling power control in applications. The Doyle-Fuller-Newman (DFN) model is a popular electrochemistry-based

Direct electrochemistry and electrocatalysis of a glucose oxidase-functionalized bioconjugate as a trace label for ultrasensitive detection of thrombin.

Science.gov (United States)

Bai, Lijuan; Yuan, Ruo; Chai, Yaqin; Yuan, Yali; Wang, Yan; Xie, Shunbi

2012-11-18

For the first time, a glucose oxidase-functionalized bioconjugate was prepared and served as a new trace label through its direct electrochemistry and electrocatalysis in a sandwich-type electrochemical aptasensor for ultrasensitive detection of thrombin.

Topic-Specific Pedagogical Content Knowledge (TSPCK) in Redox and Electrochemistry of Experienced Teachers

Science.gov (United States)

O'Brien, Stephanie

Topic specific pedagogical content knowledge (TSPCK) is the basis by which knowledge of subject matter of a particular topic is conveyed to students. This includes students' prior knowledge, curricular saliency, what makes a topic easy or difficult to teach, representations, and teaching strategies. The goal of this study is to assess the pedagogical content knowledge of chemistry teachers in a professional learning community in the areas of redox and electrochemistry, as this has been regarded in previous literature as conceptually challenging for students to learn. By acquiring information regarding the PCK development of experienced chemistry teachers, the education and practice of all science teachers can be advanced. This study builds upon previous research that developed validated instruments to evaluate TSPCK. The research questions sought to determine which components of TSPCK were evidenced by the instructional design decisions teachers made, what shared patterns and trends were evident, and how TSPCK related to student learning outcomes. To answer the research questions subjects completed a background questionnaire, a TSPCK assessment, and interview tasks to elicit information about pedagogical decision making and processes that influenced student learning in their classrooms. The TSPCK exam and interview responses were coded to align with thematic constructs. To determine the effect of TSPCK on student learning gains, pre/post-assessment data on redox and electrochemistry were compared to teachers' TSPCK. The chemistry teachers displayed varying levels of TSPCK in redox and electrochemistry, as evidenced by their knowledge of student learning obstacles, curricular saliency, and teaching methodologies. There was evidence of experienced teachers lacking in certain areas of TSPCK, such as the ability to identify student misconceptions, suggesting the need for programmatic improvements in pre-service and in-service training to address the needs of current

Humidity effect on nanoscale electrochemistry in solid silver ion conductors and the dual nature of its locality.

Science.gov (United States)

Yang, Sang Mo; Strelcov, Evgheni; Paranthaman, M Parans; Tselev, Alexander; Noh, Tae Won; Kalinin, Sergei V

2015-02-11

Scanning probe microscopy (SPM) is a powerful tool to investigate electrochemistry in nanoscale volumes. While most SPM-based studies have focused on reactions at the tip-surface junction, charge and mass conservation requires coupled and intrinsically nonlocal cathodic and anodic processes that can be significantly affected by ambient humidity. Here, we explore the role of water in both cathodic and anodic processes, associated charge transport, and topographic volume changes depending on the polarity of tip bias. The first-order reversal curve current-voltage technique combined with simultaneous detection of the sample topography, referred to as FORC-IVz, was applied to a silver solid ion conductor. We found that the protons generated from water affect silver ionic conduction, silver particle formation and dissolution, and mechanical integrity of the material. This work highlights the dual nature (simultaneously local and nonlocal) of electrochemical SPM studies, which should be considered for comprehensive understanding of nanoscale electrochemistry.

JPRS Report, Science & Technology, Japan, International Society of Electrochemistry Meeting (40th) Held in Kyoto on 17-22 Sep 89

National Research Council Canada - National Science Library

1990-01-01

Selected "extended abstracts" presented at the 40th International Society of Electrochemistry Meeting held 17-22 Sep 89 in Kyoto, sponsored by the International Union of Pure and Applied Chemistry (IUPAC...

Abrasive stripping voltammetry - a new method for the study of the electrochemistry of solid materials

International Nuclear Information System (INIS)

Scholz, F.

1992-01-01

The method is applicable to electronic conductors and non-conductors. The following applications are described: Qualitative and quantitative analysis of alloys, identification of minerals, quantitative analysis of powder mixtures, identification and study of the electrochemistry of different phases in high-T c superconductor systems, determination of stability constants of metal dithiocarbamates, study of the corrosion behaviour of dental alloys. (orig.)

Effectiveness of Interactive Multimedia Module with Pedagogical Agent (IMMPA) in the Learning of Electrochemistry: A Preliminary Investigation

Science.gov (United States)

Lee, Tien Tien; Osman, Kamisah

2011-01-01

Electrochemistry is found to be a difficult topic to learn due to its abstract concepts that involve the macroscopic, microscopic and symbolic representation levels. Research showed that animation and simulation using Information and Communication Technology (ICT) can help students to visualize and hence enhance students' understanding in learning…

Synthesis and Characterization of Aqueous Lead Selenide Quantum Dots for Solar Cell Application

Science.gov (United States)

Albert, Ancy; Sreekala, C. O.; Prabhakaran, Malini

2018-02-01

High quality, colloidal lead selenide (PbSe) nanoparticles possessing cube shaped morphology have been successfully synthesized by organometallic synthesis method, using oleic acid (OA) as capping agent. The use of non-coordinating solvent, 1-Octadecene (ODE), during the synthesis results in good quality nanocrystals. Morphology analysis by transmission electron microscopy reveals that cube-shaped nanocrystals with a size range of 10 nm have been produced during the synthesis. The absorption and PL spectra analysis showed an emission peak at 675 nm when excited to a wavelength of 610 nm, further confirmed the formation of PbSe nanocrystals. The surface modification of this colloidal quantum dots was then carried out using L- cysteine ligand, to make them water soluble, for solar cell application. The J-V characteristics study of this PbSe quantum dots solar cell (PbSe QDSC) showed a little power conversion efficiency which intern it shows significant advance toward effective utilization of PbSe nanocrystals sensitized in solar cells.

Direct electrochemistry and intramolecular electron transfer of ascorbate oxidase confined on L-cysteine self-assembled gold electrode.

Science.gov (United States)

Patil, Bhushan; Kobayashi, Yoshiki; Fujikawa, Shigenori; Okajima, Takeyoshi; Mao, Lanqun; Ohsaka, Takeo

2014-02-01

A direct electrochemistry and intramolecular electron transfer of multicopper oxidases are of a great importance for the fabrication of these enzyme-based bioelectrochemical-devices. Ascorbate oxidase from Acremonium sp. (ASOM) has been successfully immobilized via a chemisorptive interaction on the l-cysteine self-assembled monolayer modified gold electrode (cys-SAM/AuE). Thermodynamics and kinetics of adsorption of ASOM on the cys-SAM/AuE were studied using cyclic voltammetry. A well-defined redox wave centered at 166±3mV (vs. Ag│AgCl│KCl(sat.)) was observed in 5.0mM phosphate buffer solution (pH7.0) at the fabricated ASOM electrode, abbreviated as ASOM/cys-SAM/AuE, confirming a direct electrochemistry, i.e., a direct electron transfer (DET) between ASOM and cys-SAM/AuE. The direct electrochemistry of ASOM was further confirmed by taking into account the chemical oxidation of ascorbic acid (AA) by O2 via an intramolecular electron transfer in the ASOM as well as the electrocatalytic oxidation of AA at the ASOM/cys-SAM/AuE. Thermodynamics and kinetics of the adsorption of ASOM on the cys-SAM/AuE have been elaborated along with its direct electron transfer at the modified electrodes on the basis of its intramolecular electron transfer and electrocatalytic activity towards ascorbic acid oxidation and O2 reduction. ASOM saturated surface area was obtained as 2.41×10(-11)molcm(-2) with the apparent adsorption coefficient of 1.63×10(6)Lmol(-1). The ASOM confined on the cys-SAM/AuE possesses its essential enzymatic function. © 2013.

Electrochemistry Experiments to Develop Novel Sensors for Real-World Applications

Directory of Open Access Journals (Sweden)

Suzanne Lunsford

2013-08-01

Full Text Available These novel STEM (Science Technology Engineering and Mathematics Electrochemistry experiments have been designed to increase the integrated science content, pedagogical, and technological knowledge for real-world applications. This study has focused on (1 the fundamental understanding on the relationship of metal oxide films and polymers to electrochemical sensors, and (2 the development of new materials which have great application of electrode materials. Following the inquiry based learning strategy the research students learn to develop and study the electrode surfaces to meet the needs of stability and low detection limits. Recently, new advances in environmental health are revealing the anthropogenic or naturally occurring harmful organic chemicals in sources of water supply expose a great health threat to human and aquatic life. Due to their well-known carcinogenic and lethal properties, the presence of human produced toxic chemicals such as phenol and its derivatives poses a critical threat to human health and aquatic life in such water resources. In order to achieve effective assessment and monitoring of these toxic chemicals there is a need to develop in-situ (electrochemical sensors methods to detect rapidly. Electrochemical sensors have attracted more attention to analytical chemist and electrochemistry engineers due to its simplicity, rapidness and high sensitivity. However, there will be real challenges of achieving successful analysis of chemicals (phenol in the presence of common interferences in water resources, which will be discussed regarding the students challenging learning experiences in developing an electrochemical sensor. The electrochemical sensor developed (TiO2 , ZrO2 or sol-gel mixture TiO2/ZrO2 will be illustrated and the successes will be shown by cyclic voltammetry data in detection of 1,2-dihydroxybenzenes (catechol, dopamine and phenol.

Functionalizing Arrays of Transferred Monolayer Graphene on Insulating Surfaces by Bipolar Electrochemistry

DEFF Research Database (Denmark)

Koefoed, Line; Pedersen, Emil Bjerglund; Thyssen, Lena

2016-01-01

Development of versatile methods for graphene functionalization is necessary before use in applications such as composites or as catalyst support. In this study, bipolar electrochemistry is used as a wireless functionalization method to graft 4-bromobenzenediazonium on large (10 × 10 mm2) monolayer...... graphene sheets supported on SiO2. Using this technique, transferred graphene can be electrochemically functionalized without the need of a metal support or the deposition of physical contacts. X-ray photoelectron spectroscopy and Raman spectroscopy are used to map the chemical changes and modifications...

Point contacts at the copper-indium-gallium-selenide interface—A theoretical outlook

Energy Technology Data Exchange (ETDEWEB)

Bercegol, Adrien, E-mail: adrien.bercegol@polytechnique.edu; Chacko, Binoy; Klenk, Reiner; Lauermann, Iver; Lux-Steiner, Martha Ch. [Helmholtz-Zentrum Berlin für Materialien und Energie, Albert Einstein Straße 15, 12489 Berlin (Germany); Liero, Matthias [Weierstraß-Institut für Angewandte Analysis und Stochastik, 10117 Berlin (Germany)

2016-04-21

For a long time, it has been assumed that recombination in the space-charge region of copper-indium-gallium-selenide (CIGS) is dominant, at least in high efficiency solar cells with low band gap. The recent developments like potassium fluoride post deposition treatment and point-contact junction may call this into question. In this work, a theoretical outlook is made using three-dimensional simulations to investigate the effect of point-contact openings through a passivation layer on CIGS solar cell performance. A large set of solar cells is modeled under different scenarios for the charged defect levels and density, radius of the openings, interface quality, and conduction band offset. The positive surface charge created by the passivation layer induces band bending and this influences the contact (CdS) properties, making it beneficial for the open circuit voltage and efficiency, and the effect is even more pronounced when coverage area is more than 95%, and also makes a positive impact on the device performance, even in the presence of a spike at CIGS/CdS heterojunction.

DNA Electrochemistry with Tethered Methylene Blue

Science.gov (United States)

Pheeney, Catrina G.

2012-01-01

Methylene blue (MB′), covalently attached to DNA through a flexible C12 alkyl linker, provides a sensitive redox reporter in DNA electrochemistry measurements. Tethered, intercalated MB′ is reduced through DNA-mediated charge transport; the incorporation of a single base mismatch at position 3, 10, or 14 of a 17-mer causes an attenuation of the signal to 62 ± 3% of the well-matched DNA, irrespective of position in the duplex. The redox signal intensity for MB′–DNA is found to be least 3-fold larger than that of Nile blue (NB)–DNA, indicating that MB′ is even more strongly coupled to the π-stack. The signal attenuation due to an intervening mismatch does, however, depend on DNA film density and the backfilling agent used to passivate the surface. These results highlight two mechanisms for reduction of MB′ on the DNA-modified electrode: reduction mediated by the DNA base pair stack and direct surface reduction of MB′ at the electrode. These two mechanisms are distinguished by their rates of electron transfer that differ by 20-fold. The extent of direct reduction at the surface can be controlled by assembly and buffer conditions. PMID:22512327

Film Self-Assembly of Oppositely Charged Macromolecules Triggered by Electrochemistry through a Morphogenic Approach.

Science.gov (United States)

Dochter, Alexandre; Garnier, Tony; Pardieu, Elodie; Chau, Nguyet Trang Thanh; Maerten, Clément; Senger, Bernard; Schaaf, Pierre; Jierry, Loïc; Boulmedais, Fouzia

2015-09-22

The development of new surface functionalization methods that are easy to use, versatile, and allow local deposition represents a real scientific challenge. Overcoming this challenge, we present here a one-pot process that consists in self-assembling, by electrochemistry on an electrode, films made of oppositely charged macromolecules. This method relies on a charge-shifting polyanion, dimethylmaleic-modified poly(allylamine) (PAHd), that undergoes hydrolysis at acidic pH, leading to an overall switching of its charge. When a mixture of the two polyanions, PAHd and poly(styrenesulfonate) (PSS), is placed in contact with an electrode, where the pH is decreased locally by electrochemistry, the transformation of PAHd into a polycation (PAH) leads to the continuous self-assembly of a nanometric PAH/PSS film by electrostatic interactions. The pH decrease is obtained by the electrochemical oxidation of hydroquinone, which produces protons locally over nanometric distances. Using a negatively charged enzyme, alkaline phosphatase (AP), instead of PSS, this one-pot process allows the creation of enzymatically active films. Under mild conditions, self-assembled PAH/AP films have an enzymatic activity which is adjustable simply by controlling the self-assembly time. The selective functionalization of microelectrode arrays by PAH/AP was achieved, opening the route toward miniaturized biosensors.

Structural investigation of oxovanadium(IV) Schiff base complexes: X-ray crystallography, electrochemistry and kinetic of thermal decomposition

Czech Academy of Sciences Publication Activity Database

Asadi, M.; Asadi, Z.; Savaripoor, N.; Dušek, Michal; Eigner, Václav; Shorkaei, M.R.; Sedaghat, M.

2015-01-01

Roč. 136, Feb (2015), 625-634 ISSN 1386-1425 R&D Projects: GA ČR(CZ) GAP204/11/0809 Institutional support: RVO:68378271 Keywords : Oxovanadium(IV) complexes * Schiff base * Kinetic s of thermal decomposition * Electrochemistry Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.653, year: 2015

The Effect of Process Oriented Guided Inquiry Learning (POGIL) on 11th Graders' Conceptual Understanding of Electrochemistry

Science.gov (United States)

Sen, Senol; Yilmaz, Ayhan; Geban, Ömer

2016-01-01

The purpose of this study was to investigate the effect of Process Oriented Guided Inquiry Learning (POGIL) method compared to traditional teaching method on 11th grade students' conceptual understanding of electrochemistry concepts. Participants were 115 students from a public school in Turkey. Nonequivalent control group design was used. Two…

Electro-Fermentation - Merging Electrochemistry with Fermentation in Industrial Applications.

Science.gov (United States)

Schievano, Andrea; Pepé Sciarria, Tommy; Vanbroekhoven, Karolien; De Wever, Heleen; Puig, Sebastià; Andersen, Stephen J; Rabaey, Korneel; Pant, Deepak

2016-11-01

Electro-fermentation (EF) merges traditional industrial fermentation with electrochemistry. An imposed electrical field influences the fermentation environment and microbial metabolism in either a reductive or oxidative manner. The benefit of this approach is to produce target biochemicals with improved selectivity, increase carbon efficiency, limit the use of additives for redox balance or pH control, enhance microbial growth, or in some cases enhance product recovery. We discuss the principles of electrically driven fermentations and how EF can be used to steer both pure culture and microbiota-based fermentations. An overview is given on which advantages EF may bring to both existing and innovative industrial fermentation processes, and which doors might be opened in waste biomass utilization towards added-value biorefineries. Copyright © 2016 Elsevier Ltd. All rights reserved.

In situ generation of copper cations and complexation with tebuconazole in a hyphenation of electrochemistry with mass spectrometry

Czech Academy of Sciences Publication Activity Database

Jaklová Dytrtová, Jana; Jakl, M.; Schröder, Detlef; Norková, Renáta

2013-01-01

Roč. 338, 15 MAR (2013), s. 45-49 ISSN 1387-3806 R&D Projects: GA ČR GP13-21409P Institutional support: RVO:61388963 Keywords : electrochemical ion generation * ESI-MS * coupling * fungicide * tebuconazole * soil solution Subject RIV: CG - Electrochemistry Impact factor: 2.227, year: 2013

Impact of Interactive Multimedia Module with Pedagogical Agents on Students' Understanding and Motivation in the Learning of Electrochemistry

Science.gov (United States)

Osman, Kamisah; Lee, Tien Tien

2014-01-01

The Electrochemistry topic is found to be difficult to learn due to its abstract concepts involving macroscopic, microscopic, and symbolic representation levels. Studies have shown that animation and simulation using information and communication technology (ICT) can help students to visualize and hence enhance their understanding in learning…

Surfactant-Templated TiO.sub.2./sub. (Anatase): Characteristic Features of Lithium Insertion Electrochemistry in Organized Nanostructures

Czech Academy of Sciences Publication Activity Database

Kavan, Ladislav; Rathouský, Jiří; Grätzel, M.; Shklover, V.; Zukal, Arnošt

2000-01-01

Roč. 104, č. 50 (2000), s. 12012-12020 ISSN 1089-5647 R&D Projects: GA AV ČR IAA4040804; GA MŠk OC D14.10; GA AV ČR KSK2050602 Institutional research plan: CEZ:AV0Z4040901 Subject RIV: CG - Electrochemistry Impact factor: 3.386, year: 2000

Immobilization of horseradish peroxidase on self-assembled (3-mercaptopropyl)trimethoxysilane film: Characterization, direct electrochemistry, redox thermodynamics and biosensing

International Nuclear Information System (INIS)

Wu Fanghua; Hu Zhichao; Xu Jingjing; Tian Yuan; Wang Liwei; Xian Yuezhong; Jin Litong

2008-01-01

Highly organized (3-mercaptopropyl)trimethoxysilane (3-MPT) films have been prepared via self-assembled coupled with sol-gel linking technology. Horseradish peroxidase (HRP) is successfully immobilized onto the densely packed three-dimensional (3D) 3-MPT network and the direct electrochemistry of HRP is achieved without any electron mediators or promoters. Redox thermodynamics of HRP on the 3-MPT films, which is obtained from the temperature dependence of the reduction potential, suggests that the positive shift of redox potentials of HRP at the interface of 3-MPT originates from the solvent reorganization effects and conformational change of the polypeptide chain of HRP. Based on the direct electrochemistry and electrocatalytic ability of HRP, a sensitive third-generation amperometric H 2 O 2 biosensor is developed with two linear dependence ranges of 5.0 x 10 -7 to 1.0 x 10 -4 and 1.0 x 10 -4 to 2.0 x 10 -2 mol L -1

Electrochemistry of metalloproteins: protein film electrochemistry for the study of E. coli [NiFe]-hydrogenase-1.

Science.gov (United States)

Evans, Rhiannon M; Armstrong, Fraser A

2014-01-01

Protein film electrochemistry is a technique which allows the direct control of redox-active enzymes, providing particularly detailed information on their catalytic properties. The enzyme is deposited onto a working electrode tip, and through control of the applied potential the enzyme activity is monitored as electrical current, allowing for direct study of inherent activity as electrons are transferred to and from the enzyme redox center(s). No mediators are used. Because the only enzyme present in the experiment is bound at the electrode surface, gaseous and liquid phase inhibitors can be introduced and removed whilst the enzyme remains in situ. Potential control means that kinetics and thermodynamics are explored simultaneously; the kinetics of a reaction can be studied as a function of potential. Steady-state catalytic rates are observed directly as current (for a given potential) and non-steady-state rates (such as interconversions between different forms of the enzyme) are observed from the change in current with time. The more active the enzyme, the higher the current and the better the signal-to-noise. In this chapter we outline the practical aspects of PFE for studying electroactive enzymes, using the Escherichia coli [NiFe]-hydrogenase 1 (Hyd-1) as an example.

From supramolecular electrochemistry to molecular-level devices

Energy Technology Data Exchange (ETDEWEB)

Credi, Alberto; Ferrer Ribera, Belen; Venturi, Margherita

2004-09-15

Supramolecular (multi-component) systems can perform complex functions which result from the cooperation of actions performed by suitably selected molecular components. Looking at supramolecular systems, from the viewpoint of the functions, shows that the concept of macroscopic device can be extended to molecular level. Nature exploits very complex molecular-level devices to substain life, and, in the last twenty years, the development of supramolecular chemistry has allowed the construction of simple molecular-level devices, that are of interest not only for basic research, but also for the growth of nanoscience and nanotechnology. Molecular-level devices operate via electronic and/or nuclear rearrangements, and like macroscopic devices, they need energy to operate and signals to communicate with the operator. Electrochemistry can provide the answer to this dual requirement, since electrons/holes, besides supplying the energy needed to make a devices work, can also be useful to 'read' the state of the system and thus to control and monitor the operation of the device. In this article, some examples of molecular-level devices investigated in our laboratory will be reviewed.

Hydrothermal synthesis of layered iron-chalcogenide superconductors and related compounds

International Nuclear Information System (INIS)

Pachmayr, Ursula Elisabeth

2017-01-01

This thesis provides a new preparative approach to iron-chalcogenide based superconductors. The hydrothermal synthesis of anti-PbO type FeSe, which can be seen as basis structure of the compounds of interest was successfully developed. Along with this, some insights regarding the influence of synthesis parameters were gained featuring a basis for further hydrothermal syntheses of new iron-chalcogenide compounds. The potential of this method, primarily the extension of the so far limited accessibility of iron-chalcogenide based superconductors by solid-state sythesis, was revealed within the present work. The solid-solution FeSe_1_-_xS_x was prepared for the whole substitution range, whereas solid-state synthesis exhibits a solubility limit at x = 0.3. Furthermore, the new compounds [(Li_0_._8Fe_0_._2)OH]FeX (X = Se, S) were synthesized which are exclusively accessible via hydrothermal method. The compounds, where layers of (Li_0_._8Fe_0_._2)OH alternate with FeX layers, feature exceptional physical properties, notably a coexistence of superconductivity and ferromagnetism. They were intensively studied within this work. By combination of solid-state and hydrothermal ion-exchange synthesis even large crystals necessary for subsequent physical measurements are accessible. Apart from these layered iron-chalcogenide superconductors, further compounds which likewise exhibit building blocks of edge-sharing FeSe_4 tetrahedra were found via this synthesis method. The iron selenides A_2Fe_4Se_6 (A = K, Rb, Cs) consist of double chains of [Fe_2Se_3]"1"-, whereas a new compound Na_6(H_2O)_1_8Fe_4Se_8 exhibits [Fe_4Se_8]"6"- 'stella quadrangula' clusters. This structural diversity as well as the associated physical properties of the compounds demonstrates the numerous capabilities of hydrothermal synthesis in the field of iron-chalcogenide compounds. In particular with regard to iron-chalcogenide based superconductors this synthesis strategy is encouraging. It seems probable

Hydrothermal synthesis of layered iron-chalcogenide superconductors and related compounds

Energy Technology Data Exchange (ETDEWEB)

Pachmayr, Ursula Elisabeth

2017-04-06

This thesis provides a new preparative approach to iron-chalcogenide based superconductors. The hydrothermal synthesis of anti-PbO type FeSe, which can be seen as basis structure of the compounds of interest was successfully developed. Along with this, some insights regarding the influence of synthesis parameters were gained featuring a basis for further hydrothermal syntheses of new iron-chalcogenide compounds. The potential of this method, primarily the extension of the so far limited accessibility of iron-chalcogenide based superconductors by solid-state sythesis, was revealed within the present work. The solid-solution FeSe{sub 1-x}S{sub x} was prepared for the whole substitution range, whereas solid-state synthesis exhibits a solubility limit at x = 0.3. Furthermore, the new compounds [(Li{sub 0.8}Fe{sub 0.2})OH]FeX (X = Se, S) were synthesized which are exclusively accessible via hydrothermal method. The compounds, where layers of (Li{sub 0.8}Fe{sub 0.2})OH alternate with FeX layers, feature exceptional physical properties, notably a coexistence of superconductivity and ferromagnetism. They were intensively studied within this work. By combination of solid-state and hydrothermal ion-exchange synthesis even large crystals necessary for subsequent physical measurements are accessible. Apart from these layered iron-chalcogenide superconductors, further compounds which likewise exhibit building blocks of edge-sharing FeSe{sub 4} tetrahedra were found via this synthesis method. The iron selenides A{sub 2}Fe{sub 4}Se{sub 6} (A = K, Rb, Cs) consist of double chains of [Fe{sub 2}Se{sub 3}]{sup 1-}, whereas a new compound Na{sub 6}(H{sub 2}O){sub 18}Fe{sub 4}Se{sub 8} exhibits [Fe{sub 4}Se{sub 8}]{sup 6-} 'stella quadrangula' clusters. This structural diversity as well as the associated physical properties of the compounds demonstrates the numerous capabilities of hydrothermal synthesis in the field of iron-chalcogenide compounds. In particular with regard

Electrochemistry of sulfur and polysulfides in ionic liquids.

Science.gov (United States)

Manan, Ninie S A; Aldous, Leigh; Alias, Yatimah; Murray, Paul; Yellowlees, Lesley J; Lagunas, M Cristina; Hardacre, Christopher

2011-12-01

The electrochemistry of elemental sulfur (S(8)) and the polysulfides Na(2)S(4) and Na(2)S(6) has been studied for the first time in nonchloroaluminate ionic liquids. The cyclic voltammetry of S(8) in the ionic liquids is different to the behavior reported in some organic solvents, with two reductions and one oxidation peak observed. Supported by in situ UV-vis spectro-electrochemical experiments, the main reduction products of S(8) in [C(4)mim][DCA] ([C(4)mim] = 1-butyl-3-methylimidazolium; DCA = dicyanamide) have been identified as S(6)(2-) and S(4)(2-), and plausible pathways for the formation of these species are proposed. Dissociation and/or disproportionation of the polyanions S(6)(2-) and S(4)(2-) appears to be slow in the ionic liquid, with only small amounts of the blue radical species S(3)(•-) formed in the solutions at r.t., in contrast with that observed in most molecular solvents. © 2011 American Chemical Society

Post-test analysis of components from selenide isotope generator modules M-7, M-15, and M-18

International Nuclear Information System (INIS)

Wei, G.C.; Keiser, J.R.; Crouse, R.S.; Allen, M.D.; Schaffhauser, A.C.

1979-05-01

Several critical components removed from SIG (Selenide Isotope Generator) thermoelectric modules M-7, M-15C, M-15D, and M-18 were examined. These modules failed to show the predicted stability and conversion efficiency. Understanding the degradation and identifying means for preventing it necessitated detailed post-test examinations of key parts in the modules. Steel springs, which provided pressure for contacts at the hot and cold ends of P- or N-legs, relaxed more than expected. Beryllium oxide insulators had dark deposits that caused electrical shorts. The GdSe 1 49 N-leg exhibited cracking. The (Cu,Ag) 2 Se P-leg lost weight or sublimed excessively in module M-7 and more than expected in the other modules

Field Effect Transistors Using Atomically Thin Layers of Copper Indium Selenide (CuInSe)

Science.gov (United States)

Patil, Prasanna; Ghosh, Sujoy; Wasala, Milinda; Lei, Sidong; Vajtai, Robert; Ajayan, Pulickel; Talapatra, Saikat

We will report fabrication of field-effect transistors (FETs) using few-layers of Copper Indium Selenide (CuInSe) flakes exfoliated from crystals grown using chemical vapor transport technique. Our transport measurements indicate n-type FET with electron mobility µ ~ 3 cm2 V-1 s-1 at room temperature when Silicon dioxide (SiO2) is used as a back gate. Mobility can be further increased significantly when ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) is used as top gate. Similarly subthreshold swing can be further improved from 103 V/dec to 0.55 V/dec by using ionic liquid as a top gate. We also found ON/OFF ratio of ~ 102 for both top and back gate. Comparison between ionic liquid top gate and SiO2 back gate will be presented and discussed. This work is supported by the U.S. Army Research Office through a MURI Grant # W911NF-11-1-0362.

Synthesis of Co-Electrospun Lead Selenide Nanostructures within Anatase Titania Nanotubes for Advanced Photovoltaics

Directory of Open Access Journals (Sweden)

Evan K. Wujcik

2015-06-01

Full Text Available Inorganic nano-scale heterostructures have many advantages over hybrid organic-inorganic dye-sensitized solar cells (DSSC or Grätzel cells, including their resistance to photo-bleaching, thermal stability, large specific surface areas, and general robustness. This study presents a first-of-its-kind low-cost all-inorganic lead selenide-anatase titania (PbSe/TiO2 nanotube heterostructure material for photovoltaic applications. Herein, PbSe nanostructures have been co-electrospun within a hollow TiO2 nanotube with high connectivity for highly efficient charge carrier flow and electron-hole pair separation. This material has been characterized by transmission electron microscopy (TEM, electron diffraction, energy dispersive X-ray spectroscopy (EDX to show the morphology and material composition of the synthesized nanocomposite. Photovoltaic characterization has shown this newly synthesized proof-of-concept material can easily produce a photocurrent under solar illumination, and, with further refinement, could reveal a new direction in photovoltaic materials.

Sulfur ligand mediated electrochemistry of gold surfaces and nanoparticles: what, how, and why

DEFF Research Database (Denmark)

Chi, Qijin; Ford, Michael J.; Halder, Arnab

2017-01-01

Gold surfaces are widely used in electrochemistry whilst gold nanoparticles have very many uses, with both the surfaces and the particles often being protected by sulfur-bound organic ligands. The ligands not only provide chemical stability but also directly participate in many desired processes....... This review considers the diversity of known atomic structures for gold-sulfur interfaces, how these structures facilitate a diversity of mechanisms in electrochemical applications, and why this is possible based on recent advances in the basic understanding of the electronic structure of gold-sulfur bonds...

Synthesis, Structures, and Electrochemistry of Group 6 Aminocarbenes with a P -Chelating 1''-(Diphenylphosphino)ferrocenyl Substituent

Czech Academy of Sciences Publication Activity Database

Meca, L.; Dvořák, D.; Ludvík, Jiří; Císařová, I.; Štěpnička, P.

2004-01-01

Roč. 23, č. 10 (2004), s. 2541-2551 ISSN 0276-7333 R&D Projects: GA ČR GA203/04/0487; GA ČR GA203/99/M037; GA ČR GP203/01/P002 Institutional research plan: CEZ:AV0Z4040901 Keywords : synthesis * electrochemistry of group 6 * chelating Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.196, year: 2004

The influence of Mn on the crystallography and electrochemistry of nonstoichiometric AB5-type hydride-forming compounds

International Nuclear Information System (INIS)

Notten, P.H.L.; Latroche, M.; Percheron-Guegan, A.

1999-01-01

To design Co-free, low-pressure, hydride-forming compounds for application in rechargeable nickel metal hydride batteries, nonstoichiometric AB x materials were investigated. The influence of both the Mn content and the degree of nonstoichiometry on the crystallography, electrochemical cycling stability, and electrode morphology were studied. The investigated composition was in the range of La(Ni 1-z Mn z ) x with 5.0 le x le 6.0 and 0 le xz le 2.0. The annealing temperature was essential in preparing homogeneous compounds. In agreement with geometric considerations, both the a and c axis of the hexagonal unit cell increase with increasing Mn content. In contrast, the a axis decreases with increasing degree of nonstoichiometry. As proved by neutron-diffraction experiments, the introduction of dumbbell pairs of Ni or Mn atoms on the La positions in the crystal lattice is responsible for this behavior. The electrochemical cycling stability is found to be strongly dependent on both the chemical and nonstoichiometric composition. Electrochemically stable materials are characterized by the absence of a significant particle-size reduction upon electrode cycling, reducing the overall oxidation rate. Unstable materials suffer from severe mechanical cracking through which the oxidation rate is increased. The improved mechanical stability is attributed to the reduced discrete lattice expansion. The most stable compound has a partial hydrogen pressure of only 0.1 bar, which matches well with that desirable in practical NiMH batteries. Neutron-diffraction experiments confirmed the hypothesis that La atoms are replaced by dumbbell pairs of Ni, in the case of the binary LaNi 5.4 , and by Mn atoms in the case of the mn-containing nonstoichiometric compounds. Electron-probe microanalyses and density measurements support the dumbbell hypothesis

Synthesis and superconductivity of molybdenum cluster compounds (Chevrel phase)

International Nuclear Information System (INIS)

Culetto, F.J.

1979-05-01

The discovery of superconductivity in ternary molybdenum sulfides (Chevrel phases) in 1972 has stimulated research on these compounds. Some of the phases show extremely high critical fields Hc 2 and might therefore find technical application as high field superconductors. In order to understand the electron-phonon-interaction in these substances, measurements of the superconducting isotope effect in 92-100 Mo 6 Se 8 , Mo 6 76-82 Se 8 , and 116-124 SnMo 6 S 8 have been performed. The corresponding isotope effect exponents β (βmo=0.27 +- 0.04, βSe=0.27 +- 0.05 and βSn 6 Se 8 . In case of the ternary Chevrel phase SnMo 6 S 8 , phonon modes connected with displacements of the Sn-ions have only minor influence on the transition temperature. This result can be explained by the weak overlap of the molybdenum dsub(x)2sub(-y)2 - orbitals with Sn-sites. Furthermore, we report experiments on the synthesis of new Chevrel phase materials. In order to optimize the valence electron concentration in some ternary molybdenum selenide compounds, chalcogen exchange reactions have been performed. A new Chevrel phase superconductor, Cusub(x)Mo 6 S 6 J 2 with x=0 - 1.2, has been synthesized by copper diffusion into the non occupied channels running between the Mo 6 S 6 J 2 -'molecules' of Mo 6 S 6 J 2 . (orig.)

Synthesis and magnetic structure of the layered manganese oxide selenide Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Blandy, Jack N. [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom); Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Boskovic, Jelena C. [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom); Clarke, Simon J., E-mail: simon.clarke@chem.ox.ac.uk [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom)

2017-01-15

The synthesis of a high-purity sample of the layered oxide selenide Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} is reported. At ambient temperature it crystallises in the space group I4/mmm with two formula units in the unit cell and lattice parameters a=4.08771(1) Å, c=19.13087(8) Å. The compound displays mixed-valent manganese in a formal oxidation state close to +2.5 and powder neutron diffraction measurements reveal that below the Néel temperature of 63(1) K this results in an antiferromagnetic structure which may be described as A-type, modelled in the magnetic space group P{sub I}4/mnc (128.410 in the Belov, Neronova and Smirnova (BNS) scheme) in which localised Mn moments of 3.99(2) μ{sub B} are arranged in ferromagnetic layers which are coupled antiferromagnetically. In contrast to the isostructural compound Sr{sub 2}MnO{sub 2}Cu{sub 1.5}S{sub 2}, Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} does not display long range ordering of coinage metal ions and vacancies, nor may significant amounts of the coinage metal readily be deintercalated using soft chemical methods. - Graphical abstract: Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} containing mixed valent Mn ions undergoes magnetic ordering with ferromagnetic coupling within MnO{sub 2} sheets and antiferromagnetic coupling between MnO{sub 2} sheets. - Highlights: • High purity sample of Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} obtained. • Magnetic structure determined. • Compared with related mixed-valent manganite oxide chalcogenides.

Photoconductivity in reactively evaporated copper indium selenide thin films

Science.gov (United States)

Urmila, K. S.; Asokan, T. Namitha; Pradeep, B.; Jacob, Rajani; Philip, Rachel Reena

2014-01-01

Copper indium selenide thin films of composition CuInSe2 with thickness of the order of 130 nm are deposited on glass substrate at a temperature of 423 ±5 K and pressure of 10-5 mbar using reactive evaporation, a variant of Gunther's three temperature method with high purity Copper (99.999%), Indium (99.999%) and Selenium (99.99%) as the elemental starting materials. X-ray diffraction (XRD) studies shows that the films are polycrystalline in nature having preferred orientation of grains along the (112) plane. The structural type of the film is found to be tetragonal with particle size of the order of 32 nm. The structural parameters such as lattice constant, particle size, dislocation density, number of crystallites per unit area and strain in the film are also evaluated. The surface morphology of CuInSe2 films are studied using 2D and 3D atomic force microscopy to estimate the grain size and surface roughness respectively. Analysis of the absorption spectrum of the film recorded using UV-Vis-NIR Spectrophotometer in the wavelength range from 2500 nm to cutoff revealed that the film possess a direct allowed transition with a band gap of 1.05 eV and a high value of absorption coefficient (α) of 106 cm-1 at 570 nm. Photoconductivity at room temperature is measured after illuminating the film with an FSH lamp (82 V, 300 W). Optical absorption studies in conjunction with the good photoconductivity of the prepared p-type CuInSe2 thin films indicate its suitability in photovoltaic applications.

Relative Effect of Lecture Method Supplemented with Music and Computer Animation on Senior Secondary School Students' Retention in Electrochemistry

Science.gov (United States)

Akpoghol, T. V.; Ezeudu, F. O.; Adzape, J. N.; Otor, E. E.

2016-01-01

The study investigated the effects of Lecture Method Supplemented with Music (LMM) and Computer Animation (LMC) on senior secondary school students' retention in electrochemistry in Makurdi metropolis. Three research questions and three hypotheses guided the study. The design of the study was quasi experimental, specifically the pre-test,…

Plastic reactor suitable for high pressure and supercritical fluid electrochemistry

DEFF Research Database (Denmark)

Branch, Jack; Alibouri, Mehrdad; Cook, David A.

2017-01-01

The paper describes a reactor suitable for high pressure, particularly supercritical fluid, electrochemistry and electrodeposition at pressures up to 30 MPa at 115◦C. The reactor incorporates two key, new design concepts; a plastic reactor vessel and the use of o-ring sealed brittle electrodes...... by the deposition of Bi. The application of the reactor to the production of nanostructures is demonstrated by the electrodeposition of ∼80 nm diameter Te nanowires into an anodic alumina on silicon template. Key advantages of the new reactor design include reduction of the number of wetted materials, particularly...... glues used for insulating electrodes, compatability with reagents incompatible with steel, compatability with microfabricated planar multiple electrodes, small volume which brings safety advantages and reduced reagent useage, and a significant reduction in experimental time....

A compact double crystal monochromator for electrochemistry beamline at PLS

CERN Document Server

Rah, S; Kim, G H

2001-01-01

A compact double crystal monochromator based on 16.5'' CF flange has been designed, fabricated and installed for electrochemistry beamline at Pohang light source. The Bragg angle range of the monochromator is 7-75 deg. The mechanical design is modified from typical Boomerang design [J.A. Golovchenko et al., Rev. Sci. Instrum. 52 (1981) 509; J.P. Kirkland, Nucl. Instr. and Meth. A291 (1990) 185] to have fixed beam offset and single driving axis for spectroscopy experiments. The parallelism error of the crystals is minimized to less than 6 mu rad for the range, by using a precision single axis linear guide, Also, the number of mechanical parts in the vacuum is minimized and 1.8x10 sup - sup 9 Torr of vacuum is achieved without baking.

Effects of Lecture Method Supplemented with Music and Computer Animation on Senior Secondary School Students' Academic Achievement in Electrochemistry

Science.gov (United States)

Akpoghol, T. V.; Ezeudu, F. O.; Adzape, J. N.; Otor, E. E.

2016-01-01

The study investigated the effects of Lecture Method Supplemented with Music (LMM) and Computer Animation (LMC) on senior secondary school students' academic achievement in electrochemistry in Makurdi metropolis. Six research questions and six hypotheses guided the study. The design of the study was quasi experimental, specifically the pre-test,…

Developments in Synthetic Application of Selenium(IV Oxide and Organoselenium Compounds as Oxygen Donors and Oxygen-Transfer Agents

Directory of Open Access Journals (Sweden)

Jacek Młochowski

2015-06-01

Full Text Available A variety of selenium compounds were proven to be useful reagents and catalysts for organic synthesis over the past several decades. The most interesting aspect, which emerged in recent years, concerns application of hydroperoxide/selenium(IV oxide and hydroperoxide/organoselenium catalyst systems, as “green reagents” for the oxidation of different organic functional groups. The topic of oxidations catalyzed by organoselenium derivatives has rapidly expanded in the last fifteen years This paper is devoted to the synthetic applications of the oxidation reactions mediated by selenium compounds such as selenium(IV oxide, areneseleninic acids, their anhydrides, selenides, diselenides, benzisoselenazol-3(2H-ones and other less often used other organoselenium compounds. All these compounds have been successfully applied for various oxidations useful in practical organic syntheses such as epoxidation, 1,2-dihydroxylation, and α-oxyfunctionalization of alkenes, as well as for ring contraction of cycloalkanones, conversion of halomethyl, hydroxymethyl or active methylene groups into formyl groups, oxidation of carbonyl compounds into carboxylic acids and/or lactones, sulfides into sulfoxides, and secondary amines into nitrones and regeneration of parent carbonyl compounds from their azomethine derivatives. Other reactions such as dehydrogenation and aromatization, active carbon-carbon bond cleavage, oxidative amidation, bromolactonization and oxidation of bromide for subsequent reactions with alkenes are also successfully mediated by selenium (IV oxide or organoselenium compounds. The oxidation mechanisms of ionic or free radical character depending on the substrate and oxidant are discussed. Coverage of the literature up to early 2015 is provided. Links have been made to reviews that summarize earlier literature and to the methods of preparation of organoselenium reagents and catalysts.

The electrochemical reduction processes of solid compounds in high temperature molten salts.

Science.gov (United States)

Xiao, Wei; Wang, Dihua

2014-05-21

Solid electrode processes fall in the central focus of electrochemistry due to their broad-based applications in electrochemical energy storage/conversion devices, sensors and electrochemical preparation. The electrolytic production of metals, alloys, semiconductors and oxides via the electrochemical reduction of solid compounds (especially solid oxides) in high temperature molten salts has been well demonstrated to be an effective and environmentally friendly process for refractory metal extraction, functional materials preparation as well as spent fuel reprocessing. The (electro)chemical reduction of solid compounds under cathodic polarizations generally accompanies a variety of changes at the cathode/melt electrochemical interface which result in diverse electrolytic products with different compositions, morphologies and microstructures. This report summarizes various (electro)chemical reactions taking place at the compound cathode/melt interface during the electrochemical reduction of solid compounds in molten salts, which mainly include: (1) the direct electro-deoxidation of solid oxides; (2) the deposition of the active metal together with the electrochemical reduction of solid oxides; (3) the electro-inclusion of cations from molten salts; (4) the dissolution-electrodeposition process, and (5) the electron hopping process and carbon deposition with the utilization of carbon-based anodes. The implications of the forenamed cathodic reactions on the energy efficiency, chemical compositions and microstructures of the electrolytic products are also discussed. We hope that a comprehensive understanding of the cathodic processes during the electrochemical reduction of solid compounds in molten salts could form a basis for developing a clean, energy efficient and affordable production process for advanced/engineering materials.

X-ray crystallography, electrochemistry, spectral and thermal analysis of some tetradentate schiff base complexes and formation constant measurements

Czech Academy of Sciences Publication Activity Database

Asadi, Z.; Savarypour, N.; Dušek, Michal; Eigner, Václav

2017-01-01

Roč. 47, č. 11 (2017), s. 1501-1508 ISSN 2470-1556 R&D Projects: GA ČR(CZ) GA15-12653S Institutional support: RVO:68378271 Keywords : X-ray crystallography * transition metal Schiff base complexes * thermogravimetry * electrochemistry * formation constant measurements Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.)

Chemical bath deposited zinc sulfide buffer layers for copper indium gallium sulfur-selenide solar cells and device analysis

International Nuclear Information System (INIS)

Kundu, Sambhu; Olsen, Larry C.

2005-01-01

Cadmium-free copper indium gallium sulfur-selenide (CIGSS) thin film solar cells have been fabricated using chemical bath deposited (CBD) zinc sulfide (ZnS) buffer layers. Shell Solar Industries provided high quality CIGSS absorber layers. The use of CBD-ZnS, which is a higher band gap material than CdS, improved the quantum efficiency of fabricated cells at lower wavelengths, leading to an increase in short circuit current. The best cell to date yielded an active area (0.43 cm 2 ) efficiency of 13.3%. The effect of the ZnS buffer layer thickness on device performance was studied carefully. This paper also presents a discussion of issues relevant to the use of the CBD-ZnS buffer material for improving device performance

Corrosion of structural materials and electrochemistry in high temperature water of nuclear power systems

International Nuclear Information System (INIS)

Uchida, Shunsuke

2014-01-01

The latest experiences with corrosion in the cooling systems of nuclear power plants are reviewed. High temperature cooling water causes corrosion of structural materials, which often leads to adverse effects in the plants, e.g., generating defects in materials of major components and fuel claddings, increasing shutdown radiation and increasing the volume of radwaste sources. Corrosion behaviors are much affected by water qualities and differ according to the values of water qualities and the materials themselves. In order to establish reliable operation, each plant requires its own unique optimal water chemistry control based on careful consideration of its system, materials and operational history. Electrochemistry is one of key issues that determine corrosion related problems but it is not the only issue. Most phenomena for corrosion related problems, e.g., flow-accelerated corrosion (FAC), intergranular stress corrosion cracking (IGSCC), primary water stress corrosion cracking (PWSCC) and thinning of fuel cladding materials, can be understood based on an electrochemical index, e.g., electrochemical corrosion potential (ECP), conductivities and pH. The most important electrochemical index, ECP, can be measured at elevated temperature and applied to in situ sensors of corrosion conditions to detect anomalous conditions of structural materials at their very early stages. In the paper, theoretical models based on electrochemistry to estimate wall thinning rate of carbon steel piping due to flow-accelerated corrosion and corrosive conditions determining IGSCC crack initiation and growth rate are introduced. (author)

Analysis of the electrochemistry of hemes with Ems spanning 800 mV

Science.gov (United States)

Zheng, Zhong; Gunner, M. R.

2009-01-01

The free energy of heme reduction in different proteins is found to vary over more than 18 kcal/mol. It is a challenge to determine how proteins manage to achieve this enormous range of Ems with a single type of redox cofactor. Proteins containing 141 unique hemes of a-, b-, and c-type, with bis-His, His-Met, and aquo-His ligation were calculated using Multi-Conformation Continuum Electrostatics (MCCE). The experimental Ems range over 800 mV from −350 mV in cytochrome c3 to 450 mV in cytochrome c peroxidase (vs. SHE). The quantitative analysis of the factors that modulate heme electrochemistry includes the interactions of the heme with its ligands, the solvent, the protein backbone, and sidechains. MCCE calculated Ems are in good agreement with measured values. Using no free parameters the slope of the line comparing calculated and experimental Ems is 0.73 (R2 = 0.90), showing the method accounts for 73% of the observed Em range. Adding a +160 mV correction to the His-Met c-type hemes yields a slope of 0.97 (R2 = 0.93). With the correction 65% of the hemes have an absolute error smaller than 60 mV and 92% are within 120 mV. The overview of heme proteins with known structures and Ems shows both the lowest and highest potential hemes are c-type, whereas the b-type hemes are found in the middle Em range. In solution, bis-His ligation lowers the Em by ≈205 mV relative to hemes with His-Met ligands. The bis-His, aquo-His, and His-Met ligated b-type hemes all cluster about Ems which are ≈200 mV more positive in protein than in water. In contrast, the low potential bis-His c-type hemes are shifted little from in solution, whereas the high potential His-Met c-type hemes are raised by ≈300 mV from solution. The analysis shows that no single type of interaction can be identified as the most important in setting heme electrochemistry in proteins. For example, the loss of solvation (reaction field) energy, which raises the Em, has been suggested to be a major factor in

IR Laser-Induced Co-decomposition of Dimethyl Selenide and Trisilane: Gas-Phase Formation of SiSe and Chemical Vapor Deposition of Nanostructured H/Si/Se/C Polymers.

Czech Academy of Sciences Publication Activity Database

Santos, M.; Díaz, L.; Urbanová, Markéta; Bastl, Zdeněk; Šubrt, Jan; Pola, Josef

2007-01-01

Roč. 188, 2-3 (2007) , s. 399-408 ISSN 1010-6030 R&D Projects: GA MŠk(CZ) ME 846 Grant - others:MCyT(ES) BQU2003/08531/C02/02 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40320502; CEZ:AV0Z40400503 Keywords : laser deposition * laser-induced polymers * silicon selenide Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 1.911, year: 2007

Efficient cold cathode emission in crystalline-amorphous hybrid: Study on carbon nanotube-cadmium selenide system

Science.gov (United States)

Sarkar, S.; Banerjee, D.; Das, N. S.; Ghorai, U. K.; Sen, D.; Chattopadhyay, K. K.

2018-03-01

Cadmium Selenide (CdSe) quantum dot (QD) decorated amorphous carbon nanotubes (a-CNTs) hybrids have been synthesized by simple chemical process. The samples were characterized by field emission scanning and transmission electron microscopy, Fourier transformed infrared spectroscopy, Raman and UV-Vis spectroscopy. Lattice image obtained from transmission electron microscopic study confirms the successful attachment of CdSe QDs. It is seen that hybrid samples show an enhanced cold emission properties with good stability. The results have been explained in terms of increased roughness, more numbers of emitting sites and favorable band bending induced electron transport. ANSYS software based calculation has also supported the result. Also a first principle based study has been done which shows that due to the formation of hybrid structure there is a profound upward shift in the Fermi level, i.e. a decrease of work function, which is believed to be another key reason for the observed improved field emission performance.

Swift heavy ion induced modifications in optical and electrical properties of cadmium selenide thin films

Science.gov (United States)

Choudhary, Ritika; Chauhan, Rishi Pal

2017-07-01

The modification in various properties of thin films using high energetic ion beam is an exciting area of basic and applied research in semiconductors. In the present investigations, cadmium selenide (CdSe) thin films were deposited on ITO substrate using electrodeposition technique. To study the swift heavy ion (SHI) induced effects, the deposited thin films were irradiated with 120 MeV heavy Ag9+ ions using pelletron accelerator facility at IUAC, New Delhi, India. Structural phase transformation in CdSe thin film from metastable cubic phase to stable hexagonal phase was observed after irradiation leading to decrease in the band gap from 2.47 eV to 2.12 eV. The phase transformation was analyzed through X-ray diffraction patterns. During SHI irradiation, Generation of high temperature and pressure by thermal spike along the trajectory of incident ions in the thin films might be responsible for modification in the properties of thin films.[Figure not available: see fulltext.

Electrochemistry of plutonium in molten halides

International Nuclear Information System (INIS)

McCurry, L.E.; Moy, G.M.M.; Bowersox, D.F.

1987-01-01

The electrochemistry of plutonium in molten halides is of technological importance as a method of purification of plutonium. Previous authors have reported that plutonium can be purified by electrorefining impure plutonium in various molten haldies. Work to eluciate the mechanism of the plutonium reduction in molten halides has been limited to a chronopotentiometric study in LiCl-KCl. Potentiometric studies have been carried out to determine the standard reduction potential for the plutonium (III) couple in various molten alkali metal halides. Initial cyclic voltammetric experiments were performed in molten KCL at 1100 K. A silver/silver chloride (10 mole %) in equimolar NaCl-KCl was used as a reference electrode. Working and counter electrodes were tungsten. The cell components and melt were contained in a quartz crucible. Background cyclic voltammograms of the KCl melt at the tungsten electrode showed no evidence of electroactive impurities in the melt. Plutonium was added to the melt as PuCl/sub 3/, which was prepared by chlorination of the oxide. At low concentrations of PuCl/sub 3/ in the melt (0.01-0.03 molar), no reduction wave due to the reduction of Pu(III) was observed in the voltammograms up to the potassium reduction limit of the melt. However on scan reversal after scanning into the potassium reduction limit a new oxidation wave was observed

Synthesis and characterization of hexagonal nano-sized nickel selenide by simple hydrothermal method assisted by CTAB

Energy Technology Data Exchange (ETDEWEB)

Sobhani, Azam [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Davar, Fatemeh [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of)

2011-07-01

Nano-sized nickel selenide powders have been successfully synthesized via an improved hydrothermal route based on the reaction between NiCl{sub 2}.6H{sub 2}O, SeCl{sub 4} and hydrazine (N{sub 2}H{sub 4}.H{sub 2}O) in water, in present of cetyltrimethyl ammonium bromide (CTAB) as surfactant, at various conditions. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray energy dispersive spectroscopy analysis. Effects of temperature, reaction time and reductant agent on the morphology, the particle sizes and the phase of the final products have been investigated. It was found that the phase and morphology of the products could be greatly influenced by these parameters. The synthesis procedure is simple and uses less toxic reagents than the previously reported methods. Photoluminescence (PL) was used to study the optical properties of NiSe samples.

Enhanced phosphorescence and electroluminescence in triplet emitters by doping gold into cadmium selenide/zinc sulfide nanoparticles

International Nuclear Information System (INIS)

Liu, H.-W.; Laskar, Inamur R.; Huang, C.-P.; Cheng, J.-A.; Cheng, S.-S.; Luo, L.-Y.; Wang, H.-R.; Chen, T.-M.

2005-01-01

Gold-cadmium selenide/zinc sulfide (Au-CdSe/ZnS) nanocomposites (NCs) were synthesized and characterized by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, ultraviolet-visible (UV-visible) absorption and photoluminescence (PL) emission spectroscopy. The PL intensity in the Au-CdSe/ZnS NCs system was found to be much greater than that of CdSe/ZnS nanoparticles (NPs) alone, because of the surface-enhanced Raman scattering of Au NPs. Adding Au-CdSe/ZnS NCs to the cyclometalated iridium(III) complex (Ir-complex) greatly enhanced the PL intensity of a triplet emitter. Three double-layered electroluminescence (EL) devices were fabricated where the emitting zone contains the definite mixture of Ir-complex and the NCs [molar concentration of Ir-complex/NCs = 1:0 (Blank, D-1), 1:1 (D-2) and 1:3 (D-3)] and the device D-2 exhibited optimal EL performances

Layered bismuth selenide utilized as hole transporting layer for highly stable organic photovoltaics

KAUST Repository

Yuan, Zhongcheng

2015-11-01

Abstract Layered bismuth selenide (L-Bi2Se3) nanoplates were implemented as hole transporting layers (HTLs) for inverted organic solar cells. Device based on L-Bi2Se3 showed increasing power conversion efficiency (PCE) during ambient condition storage process. A PCE of 4.37% was finally obtained after 5 days storage, which outperformed the ones with evaporated-MoO3 using poly(3-hexylthiophene) (P3HT) as donor material and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as acceptor. The improved device efficiency can be attributed to the high conductivity and increasing work function of L-Bi2Se3. The work function of L-Bi2Se3 increased with the storage time in ambient condition due to the oxygen atom doping. Ultraviolet photoelectron spectroscopy and high resolution X-ray photoelectron spectroscopy were conducted to verify the increased work function, which originated from the p-type doping process. The device based on L-Bi2Se3 exhibited excellent stability in ambient condition up to 4 months, which was much improved compared to the device based on traditional HTLs. © 2015 Elsevier B.V.

Efficient solution-processed small molecule: Cadmium selenide quantum dot bulk heterojunction solar cells

International Nuclear Information System (INIS)

Gupta, Vinay; Upreti, Tanvi; Chand, Suresh

2013-01-01

We report bulk heterojunction solar cells based on blends of solution-processed small molecule [7,7′-(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b′]dithiophene-2,6-diyl) bis(6-fluoro-4-(5′-hexyl-[2,2′-bithiophen]-5yl)benzo[c] [1,2,5] thiadiazole)] p-DTS(FBTTh 2 ) 2 : Cadmium Selenide (CdSe) (70:30, 60:40, 50:50, and 40:60) in the device configuration: Indium Tin Oxide /poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/p-DTS(FBTTh 2 ) 2 : CdSe/Ca/Al. The optimized ratio of p-DTS(FBTTh 2 ) 2 :CdSe::60:40 leads to a short circuit current density (J sc ) = 5.45 mA/cm 2 , open circuit voltage (V oc ) = 0.727 V, and fill factor (FF) = 51%, and a power conversion efficiency = 2.02% at 100 mW/cm 2 under AM1.5G illumination. The J sc and FF are sensitive to the ratio of p-DTS(FBTTh 2 ) 2 :CdSe, which is a crucial factor for the device performance

Zinc Selenide-Based Schottky Barrier Detectors for Ultraviolet-A and Ultraviolet-B Detection

Directory of Open Access Journals (Sweden)

V. Naval

2010-01-01

Full Text Available Wide-bandgap semiconductors such as zinc selenide (ZnSe have become popular for ultraviolet (UV photodetectors due to their broad UV spectral response. Schottky barrier detectors made of ZnSe in particular have been shown to have both low dark current and high responsivity. This paper presents the results of electrical and optical characterization of UV sensors based on ZnSe/Ni Schottky diodes fabricated using single-crystal ZnSe substrate with integrated UV-A (320–400 nm and UV-B (280–320 nm filters. For comparison, characteristics characterization of an unfiltered detector is also included. The measured photoresponse showed good discrimination between the two spectral bands. The measured responsivities of the UV-A and UV-B detectors were 50 mA/W and 10 mA/W, respectively. A detector without a UV filter showed a maximum responsivity of about 110 mA/W at 375 nm wavelength. The speed of the unfiltered detector was found to be about 300 kHz primarily limited by the RC time constant determined largely by the detector area.

Ecotoxicological assessment of solar cell leachates: Copper indium gallium selenide (CIGS) cells show higher activity than organic photovoltaic (OPV) cells

Energy Technology Data Exchange (ETDEWEB)

Brun, Nadja Rebecca [University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz (Switzerland); Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Universitätsstrasse 16, CH-8092 Zürich (Switzerland); Wehrli, Bernhard [Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Universitätsstrasse 16, CH-8092 Zürich (Switzerland); Fent, Karl, E-mail: karl.fent@fhnw.ch [University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz (Switzerland); Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Universitätsstrasse 16, CH-8092 Zürich (Switzerland)

2016-02-01

Despite the increasing use of photovoltaics their potential environmental risks are poorly understood. Here, we compared ecotoxicological effects of two thin-film photovoltaics: established copper indium gallium selenide (CIGS) and organic photovoltaic (OPV) cells. Leachates were produced by exposing photovoltaics to UV light, physical damage, and exposure to environmentally relevant model waters, representing mesotrophic lake water, acidic rain, and seawater. CIGS cell leachates contained 583 μg L{sup −1} molybdenum at lake water, whereas at acidic rain and seawater conditions, iron, copper, zinc, molybdenum, cadmium, silver, and tin were present up to 7219 μg L{sup −1}. From OPV, copper (14 μg L{sup −1}), zinc (87 μg L{sup −1}) and silver (78 μg L{sup −1}) leached. Zebrafish embryos were exposed until 120 h post-fertilization to these extracts. CIGS leachates produced under acidic rain, as well as CIGS and OPV leachates produced under seawater conditions resulted in a marked hatching delay and increase in heart edema. Depending on model water and solar cell, transcriptional alterations occurred in genes involved in oxidative stress (cat), hormonal activity (vtg1, ar), metallothionein (mt2), ER stress (bip, chop), and apoptosis (casp9). The effects were dependent on the concentrations of cationic metals in leachates. Addition of ethylenediaminetetraacetic acid protected zebrafish embryos from morphological and molecular effects. Our study suggests that metals leaching from damaged CIGS cells, may pose a potential environmental risk. - Highlights: • Photovoltaics may be disposed in the environment after usage. • Copper indium gallium selenide (CIGS) and organic (OPV) cells were compared. • Morphological and molecular effects were assessed in zebrafish embryos. • Environmental condition affected metal leaching and ecotoxicological activity. • Damaged CIGS cells pose higher risk to the environment than OPV cells.

Electrochemistry for the Generation of Renewable Chemicals: One-Pot Electrochemical Deoxygenation of Xylose to δ-Valerolactone.

Science.gov (United States)

James, Olusola O; Sauter, Waldemer; Schröder, Uwe

2017-05-09

In this study, the electrochemical conversion of xylose to δ-valerolactone via carbonyl intermediates is demonstrated. The conversion was achieved in aqueous media and at ambient conditions. This study also demonstrates that the feedstock for production of renewable chemicals and biofuels through electrochemistry can be extended to primary carbohydrate molecules. This is the first report on a one-pot electrochemical deoxygenation of xylose to δ-valerolactone. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

High Performance Liquid Chromatography/Electrochemistry/High Resolution Electrospray Ionization-Mass Spectrometry (HPLC/EC/HR ESI-MS) Characterization of Selected Cytokinins Oxidation Products

Czech Academy of Sciences Publication Activity Database

Karady, Michal; Novák, Ondřej; Horna, A.; Strnad, Miroslav; Doležal, Karel

2015-01-01

Roč. 27, č. 2 (2015), s. 406-414 ISSN 1040-0397 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Electrochemistry * Cytokinin * Oxidative metabolism Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.471, year: 2015

A study on the optics of copper indium gallium (di)selenide (CIGS) solar cells with ultra-thin absorber layers.

Science.gov (United States)

Xu, Man; Wachters, Arthur J H; van Deelen, Joop; Mourad, Maurice C D; Buskens, Pascal J P

2014-03-10

We present a systematic study of the effect of variation of the zinc oxide (ZnO) and copper indium gallium (di)selenide (CIGS) layer thickness on the absorption characteristics of CIGS solar cells using a simulation program based on finite element method (FEM). We show that the absorption in the CIGS layer does not decrease monotonically with its layer thickness due to interference effects. Ergo, high precision is required in the CIGS production process, especially when using ultra-thin absorber layers, to accurately realize the required thickness of the ZnO, cadmium sulfide (CdS) and CIGS layer. We show that patterning the ZnO window layer can strongly suppress these interference effects allowing a higher tolerance in the production process.

An experimental applications of impedance measurements by spectral analysis to electrochemistry and corrosion

International Nuclear Information System (INIS)

Castro, E.B.; Vilche, J.R.; Milocco, R.H.

1984-01-01

An impedance measurement system based on the spectral analysis of excitation and response signals was implemented using a pseudo-random binary sequence in the generation of the electrical perturbation signal. The spectral density functions were estimated through finite Fourier transforms of the original time history records by fast computation of Fourier series. Experimental results obtained using the FFT algorithm in the developed impedance measurement system which covers a wide frequency range, 10 KHz >= f >= 1 mHz, are given both for dummy cells representing conventional electric circuits in electrochemistry and corrosion systems and for the Fe/acidic chloride solution interfaces under different polarization conditions. (C.L.B.) [pt

Nanopore Electrochemistry: A Nexus for Molecular Control of Electron Transfer Reactions

Science.gov (United States)

2018-01-01

Pore-based structures occur widely in living organisms. Ion channels embedded in cell membranes, for example, provide pathways, where electron and proton transfer are coupled to the exchange of vital molecules. Learning from mother nature, a recent surge in activity has focused on artificial nanopore architectures to effect electrochemical transformations not accessible in larger structures. Here, we highlight these exciting advances. Starting with a brief overview of nanopore electrodes, including the early history and development of nanopore sensing based on nanopore-confined electrochemistry, we address the core concepts and special characteristics of nanopores in electron transfer. We describe nanopore-based electrochemical sensing and processing, discuss performance limits and challenges, and conclude with an outlook for next-generation nanopore electrode sensing platforms and the opportunities they present. PMID:29392173

Nanopore Electrochemistry: A Nexus for Molecular Control of Electron Transfer Reactions

Directory of Open Access Journals (Sweden)

Kaiyu Fu

2018-01-01

Full Text Available Pore-based structures occur widely in living organisms. Ion channels embedded in cell membranes, for example, provide pathways, where electron and proton transfer are coupled to the exchange of vital molecules. Learning from mother nature, a recent surge in activity has focused on artificial nanopore architectures to effect electrochemical transformations not accessible in larger structures. Here, we highlight these exciting advances. Starting with a brief overview of nanopore electrodes, including the early history and development of nanopore sensing based on nanopore-confined electrochemistry, we address the core concepts and special characteristics of nanopores in electron transfer. We describe nanopore-based electrochemical sensing and processing, discuss performance limits and challenges, and conclude with an outlook for next-generation nanopore electrode sensing platforms and the opportunities they present.

In-Depth Characterization of Protein Disulfide Bonds by Online Liquid Chromatography-Electrochemistry-Mass Spectrometry

Science.gov (United States)

Switzar, Linda; Nicolardi, Simone; Rutten, Julie W.; Oberstein, Saskia A. J. Lesnik; Aartsma-Rus, Annemieke; van der Burgt, Yuri E. M.

2016-01-01

Disulfide bonds are an important class of protein post-translational modifications, yet this structurally crucial modification type is commonly overlooked in mass spectrometry (MS)-based proteomics approaches. Recently, the benefits of online electrochemistry-assisted reduction of protein S-S bonds prior to MS analysis were exemplified by successful characterization of disulfide bonds in peptides and small proteins. In the current study, we have combined liquid chromatography (LC) with electrochemistry (EC) and mass analysis by Fourier transform ion cyclotron resonance (FTICR) MS in an online LC-EC-MS platform to characterize protein disulfide bonds in a bottom-up proteomics workflow. A key advantage of a LC-based strategy is the use of the retention time in identifying both intra- and interpeptide disulfide bonds. This is demonstrated by performing two sequential analyses of a certain protein digest, once without and once with electrochemical reduction. In this way, the "parent" disulfide-linked peptide detected in the first run has a retention time-based correlation with the EC-reduced peptides detected in the second run, thus simplifying disulfide bond mapping. Using this platform, both inter- and intra-disulfide-linked peptides were characterized in two different proteins, ß-lactoglobulin and ribonuclease B. In order to prevent disulfide reshuffling during the digestion process, proteins were digested at a relatively low pH, using (a combination of) the high specificity proteases trypsin and Glu-C. With this approach, disulfide bonds in ß-lactoglobulin and ribonuclease B were comprehensively identified and localized, showing that online LC-EC-MS is a useful tool for the characterization of protein disulfide bonds.

Expedient preparation of nazlinine and a small library of indole alkaloids using flow electrochemistry as an enabling technology.

Science.gov (United States)

Kabeshov, Mikhail A; Musio, Biagia; Murray, Philip R D; Browne, Duncan L; Ley, Steven V

2014-09-05

An expedient synthesis of the indole alkaloid nazlinine is reported. Judicious choice of flow electrochemistry as an enabling technology has permitted the rapid generation of a small library of unnatural relatives of this biologically active molecule. Furthermore, by conducting the key electrochemical Shono oxidation in a flow cell, the loading of electrolyte can be significantly reduced to 20 mol % while maintaining a stable, broadly applicable process.

Formation and investigation of 6-cysteinyl amino methylated β-cyclodextrin self-assembled monolayers

Czech Academy of Sciences Publication Activity Database

Kolivoška, Viliam; Sokolová, Romana; Kocábová, Jana; Loukou, Ch.; Mallet, J.-M.; Hromadová, Magdaléna

2016-01-01

Roč. 147, č. 1 (2016), s. 45-51 ISSN 0026-9247 R&D Projects: GA ČR(CZ) GA14-05180S Grant - others:GA AV ČR(CZ) L200401501 Institutional support: RVO:61388955 Keywords : cage compounds * cyclic voltammetry * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 1.282, year: 2016

Layer structured bismuth selenides Bi2Se3 and Bi3Se4 for high energy and flexible all-solid-state micro-supercapacitors

Science.gov (United States)

Hao, Chunxue; Wang, Lidan; Wen, Fusheng; Xiang, Jianyong; Li, Lei; Hu, Wentao; Liu, Zhongyuan

2018-02-01

In this work, bismuth selenides (Bi2Se3 and Bi3Se4), both of which have a layered rhombohedral crystal structure, have been found to be useful as electrode materials for supercapacitor applications. In a liquid electrolyte system (6M KOH), Bi2Se3 nanoplates exhibit much better performance as an electrode material than Bi3Se4 nanoparticles do, delivering a higher specific capacitance (272.9 F g-1) than that of Bi3Se4 (193.6 F g-1) at 5 mV s-1. This result may be attributed to the fact that Bi2Se3 nanoplates possess more active electrochemical surfaces for the reversible surface redox reactions owing to their planar quintuple stacked layers (septuple layers for Bi3Se4). To meet the demands of electronic skin, we used a novel flexible annular interdigital structure electrode to support the all-solid-state micro-supercapacitors (AMSCs). The Bi2Se3 AMSC device delivers a much better supercapacitor performance, exhibits a large stack capacitance of 89.5 F cm-3 at 20 mV s-1 (Bi3Se4: 79.1 F cm-3), a high energy density of 17.9 mWh cm-3 and a high power density of 18.9 W cm-3. The bismuth selenides also exhibit good cycle stability, with 95.5% retention after 1000 c for Bi2Se3 (Bi3Se4:90.3%). Clearly, Bi2Se3 nanoplates can be promising electrode materials for flexible annular interdigital AMSCs.

Environmental aspects of electrochemistry and photoelectrochemistry

International Nuclear Information System (INIS)

Tomkiewicz, M.; Yoneyama, H.; Hori, Y.

1993-01-01

Arguably, the end of this century marks the beginning of an era in which an equilibrium between men and environment is no longer an option but a necessity. A full life cycle of new and old technologies will soon be a requirement. Electrochemistry probably plays a more fundamental role toward the end of the life-cycle of many technologies as compared to the beginning of the cycle. This symposium is the first of its kind within the Electrochemical Society in its attempt to unify diverse aspects of the environmental picture. In addition to the scientific interest in the various topics, this diversity reflects the various priorities that emerge in different countries. In Japan a strong emphasis is being put on the environmental consequences of CO 2 accumulation and hence the strong emphasis on CO 2 fixation. In the US and Europe the detoxification of aquatic environments seems at present to attract higher priorities. Almost everywhere there is a need to remedy the cumulative effect of total neglect since the dawn of the industrial revolution that can be traced differently in different parts of the world. In a somewhat arbitrary way the authors have divided the contributions into three categories: (1) CO 2 fixation, (2) Photocatalysis with TiO 2 , (3) Electrochemical decontaminations. Although this partition was done mainly for editorial convenience, it follows closely the clustering at the meeting. Individual papers are cataloged separately for inclusion in the appropriate data bases

Remarkable photo-catalytic degradation of malachite green by nickel doped bismuth selenide under visible light irradiation

Science.gov (United States)

Kulsi, Chiranjit; Ghosh, Amrita; Mondal, Anup; Kargupta, Kajari; Ganguly, Saibal; Banerjee, Dipali

2017-01-01

Bismuth selenide (Bi2Se3) and nickel (Ni) doped Bi2Se3 were prepared by a solvothermal approach to explore the photo-catalytic performance of the materials in degradation of malachite green (MG). The presence of nickel was confirmed by X-ray photoelectron spectroscopy (XPS) measurement in doped Bi2Se3. The results showed that the nickel doping played an important role in microstructure and photo-catalytic activity of the samples. Nickel doped Bi2Se3 sample exhibited higher photo-catalytic activity than that of the pure Bi2Se3 sample under visible-light irradiation. The photo-catalytic degradation followed first-order reaction kinetics. Fast degradation kinetics and complete (100% in 5 min of visible light irradiation) removal of MG was achieved by nickel doped Bi2Se3 in presence of hydrogen peroxide (H2O2) due to modification of band gap energies leading to suppression of photo-generated electron-hole recombination.

The effect of annealing on structural, optical and photosensitive properties of electrodeposited cadmium selenide thin films

Directory of Open Access Journals (Sweden)

Somnath Mahato

2017-06-01

Full Text Available Cadmium selenide (CdSe thin films have been deposited on indium tin oxide coated glass substrate by simple electrodeposition method. X-ray Diffraction (XRD studies identify that the as-deposited CdSe films are highly oriented to [002] direction and they belong to nanocrystalline hexagonal phase. The films are changed to polycrystalline structure after annealing in air for temperatures up to 450 °C and begin to degrade afterwards with the occurrence of oxidation and porosity. CdSe completely ceases to exist at higher annealing temperatures. CdSe films exhibit a maximum absorbance in the violet to blue-green region of an optical spectrum. The absorbance increases while the band gap decreases with increasing annealing temperature. Surface morphology also shows that the increase of the annealing temperature caused the grain growth. In addition, a number of distinct crystals is formed on top of the film surface. Electrical characteristics show that the films are photosensitive with a maximum sensitivity at 350 °C.

Improved microstructure and thermoelectric properties of iodine doped indium selenide as a function of sintering temperature

Science.gov (United States)

Dhama, Pallavi; Kumar, Aparabal; Banerji, P.

2018-04-01

In this paper, we explored the effect of sintering temperature on the microstructure, thermal and electrical properties of iodine doped indium selenide in the temperature range 300 - 700 K. Samples were prepared by a collaborative process of vacuum melting, ball milling and spark plasma sintering at 570 K, 630 K and 690 K. Single phase samples were obtained at higher sintering temperature as InSe is stable only at lower temperature. With increasing sintering temperature, densities of the samples were found to improve with larger grain size formation. Negative values of Seebeck coefficient were observed which indicates n-type carrier transport. Seebeck coefficient increases with sintering temperature and found to be the highest for the sample sintered at 690 K. Thermal conductivity found to be lower in the samples sintered at lower temperatures. The maximum thermoelectric figure of merit found to be ˜ 1 at 700 K due to the enhanced power factor as a result of improved microstructure.

Structure, electrochemistry and spectroscopy of a new diacylhydrazido-bridged diruthenium complex with a strongly near-infrared absorbing RuIIIRuII intermediate

Czech Academy of Sciences Publication Activity Database

Jana, R.; Sarkar, B.; Bubrin, D.; Fiedler, Jan; Kaim, W.

2010-01-01

Roč. 13, č. 10 (2010), s. 1160-1162 ISSN 1387-7003 R&D Projects: GA MŠk OC 140; GA MŠk OC09043 Institutional research plan: CEZ:AV0Z40400503 Keywords : crystal structure * hydrazido ligand * near-infrared ruthenium Subject RIV: CG - Electrochemistry Impact factor: 1.974, year: 2010

Direct Electrochemistry of Horseradish Peroxidase-Gold Nanoparticles Conjugate

Directory of Open Access Journals (Sweden)

Chanchal K. Mitra

2009-02-01

Full Text Available We have studied the direct electrochemistry of horseradish peroxidase (HRP coupled to gold nanoparticles (AuNP using electrochemical techniques, which provide some insight in the application of biosensors as tools for diagnostics because HRP is widely used in clinical diagnostics kits. AuNP capped with (i glutathione and (ii lipoic acid was covalently linked to HRP. The immobilized HRP/AuNP conjugate showed characteristic redox peaks at a gold electrode. It displayed good electrocatalytic response to the reduction of H2O2, with good sensitivity and without any electron mediator. The covalent linking of HRP and AuNP did not affect the activity of the enzyme significantly. The response of the electrode towards the different concentrations of H2O2 showed the characteristics of Michaelis Menten enzyme kinetics with an optimum pH between 7.0 to 8.0. The preparation of the sensor involves single layer of enzyme, which can be carried out efficiently and is also highly reproducible when compared to other systems involving the layer-by-layer assembly, adsorption or encapsulation of the enzyme. The immobilized AuNP-HRP can be used for immunosensor applications

Boundary asymptotics for a non-neutral electrochemistry model with small Debye length

Science.gov (United States)

Lee, Chiun-Chang; Ryham, Rolf J.

2018-04-01

This article addresses the boundary asymptotics of the electrostatic potential in non-neutral electrochemistry models with small Debye length in bounded domains. Under standard physical assumptions motivated by non-electroneutral phenomena in oxidation-reduction reactions, we show that the electrostatic potential asymptotically blows up at boundary points with respect to the bulk reference potential as the scaled Debye length tends to zero. The analysis gives a lower bound for the blow-up rate with respect to the model parameters. Moreover, the maximum potential difference over any compact subset of the physical domain vanishes exponentially in the zero-Debye-length limit. The results mathematically confirm the physical description that electrolyte solutions are electrically neutral in the bulk and are strongly electrically non-neutral near charged surfaces.

2006 Electrochemistry Gordon Research Conference - February 12-17-2006

Energy Technology Data Exchange (ETDEWEB)

Abruna, Hector D. [Cornell Univ., Ithaca, NY (United States)

2007-04-03

The Gordon Research Conference (GRC) on Electrochemistry was held at Santa Ynez Valley Marriott, Buellton California from February 12-17, 2006. The Conference was well-attended with 113 participants (attendees list attached). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students. In designing the formal speakers program, emphasis was placed on current unpublished research and discussion of the future target areas in this field. There was a conscious effort to stimulate lively discussion about the key issues in the field today. Time for formal presentations was limited in the interest of group discussions. In order that more scientists could communicate their most recent results, poster presentation time was scheduled. Attached is a copy of the formal schedule and speaker program and the poster program. In addition to these formal interactions, "free time" was scheduled to allow informal discussions. Such discussions are fostering new collaborations and joint efforts in the field.

Electrochemistry-assisted top-down characterization of disulfide-containing proteins.

Science.gov (United States)

Zhang, Yun; Cui, Weidong; Zhang, Hao; Dewald, Howard D; Chen, Hao

2012-04-17

Covalent disulfide bond linkage in a protein represents an important challenge for mass spectrometry (MS)-based top-down protein structure analysis as it reduces the backbone cleavage efficiency for MS/MS dissociation. This study presents a strategy for solving this critical issue via integrating electrochemistry (EC) online with a top-down MS approach. In this approach, proteins undergo electrolytic reduction in an electrochemical cell to break disulfide bonds and then undergo online ionization into gaseous ions for analysis by electron-capture dissociation (ECD) and collision-induced dissociation (CID). The electrochemical reduction of proteins allows one to remove disulfide bond constraints and also leads to increased charge numbers of the resulting protein ions. As a result, sequence coverage was significantly enhanced, as exemplified by β-lactoglobulin A (24 vs 75 backbone cleavages before and after electrolytic reduction, respectively) and lysozyme (5 vs 66 backbone cleavages before and after electrolytic reduction, respectively). This methodology is fast and does not need chemical reductants, which would have an important impact in high-throughput proteomics research.

Spectroscopy and electrochemistry of U(IV/III) in basic AlCl3-EMIC

International Nuclear Information System (INIS)

Anderson, C.J.; Deakin, M.R.; Choppin, G.R.; Heerman, L.; D'Olieslager, W.; Pruett, D.J.

1990-01-01

The electrochemistry of U(IV) has been investigated in the solvent AlCl 3 -1-ethyl-3-methyl imidazolium chloride (EMIC), a room temperature ionic liquid. In basic solutions ( 3 ) the reduction of U(IV) to U(III) on glassy carbon electrodes is reversible. Spectroscopic data as well as measurements of the formal potential for U(IV)/U(III) as a function of the basic melt composition indicate that U(IV) and U(III) are both hexachloro anions. Diffusion coefficients for these species have been measured by two methods. The values are comparable to those of transition metal hexachloro complexes in the same solvent, supporting the assignment of UCl 6 2- and UCl 6 3-

Layer Structured Bismuth Selenides of Bi2Se3 and Bi3Se4 for High Energy and Flexible All-Solid-State Micro-Supercapacitors.

Science.gov (United States)

Hao, Chunxue; Wang, Lidan; Wen, Fusheng; Xiang, Jianyong; Li, Lei; Hu, Wentao; Liu, Zhongyuan

2017-12-20

Bismuth selenides (Bi2Se3 and Bi3Se4), both of which have the layered rhombohedral crystal structure, and found to be useful as electrode materials for supercapacitor application in this work. Bi2Se3 nanoplates as electrode material exhibit much better performance than that of Bi3Se4 nanoparticles in liquid electrolyte system (6 M KOH), which delivers a higher specific capacitance (272.9 F/g) than that of Bi3Se4 (193.6 F/g) at 5 mV/s. This result would may be attributed to that Bi2Se3 nanoplates possess more active electrochemical surfaces for the reversible surface redox reactions owing to its planar quintuple stacked layers (septuple layers for Bi3Se4). For the demand of electronic skin, we used a novel flexible annular interdigital structure electrode applying for all-solid-state micro-supercapacitors (AMSCs). Bi2Se3 AMSCs device delivers a much more excellent supercapacitor performance, exhibits a large stack capacitance 89.5 F/cm3 (Bi3Se4: 79.1 F/cm3) at 20 mV/s, a high energy density 17.9 mWh/cm3 and high power density 18.9 W/cm3. The bismuth selenides also exhibit good cycle stability, retention 95.5% (90.3%) after 1000 c for Bi2Se3 (Bi3Se4). Obviously, Bi2Se3 nanoplates can be promising electrode materials for flexible annular interdigital all-solid-sate supercapacitor. © 2017 IOP Publishing Ltd.

Efficient solution-processed small molecule: Cadmium selenide quantum dot bulk heterojunction solar cells

Energy Technology Data Exchange (ETDEWEB)

Gupta, Vinay, E-mail: drvinaygupta@netscape.net [Physics of Energy Harvesting Division, Organic and Hybrid Solar Cell Group, CSIR-National Physical Laboratory, New Delhi-110012 (India); Department of Physics, University of California, Santa Barbara, California 93106 (United States); Upreti, Tanvi; Chand, Suresh [Physics of Energy Harvesting Division, Organic and Hybrid Solar Cell Group, CSIR-National Physical Laboratory, New Delhi-110012 (India)

2013-12-16

We report bulk heterojunction solar cells based on blends of solution-processed small molecule [7,7′-(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b′]dithiophene-2,6-diyl) bis(6-fluoro-4-(5′-hexyl-[2,2′-bithiophen]-5yl)benzo[c] [1,2,5] thiadiazole)] p-DTS(FBTTh{sub 2}){sub 2}: Cadmium Selenide (CdSe) (70:30, 60:40, 50:50, and 40:60) in the device configuration: Indium Tin Oxide /poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/p-DTS(FBTTh{sub 2}){sub 2}: CdSe/Ca/Al. The optimized ratio of p-DTS(FBTTh{sub 2}){sub 2}:CdSe::60:40 leads to a short circuit current density (J{sub sc}) = 5.45 mA/cm{sup 2}, open circuit voltage (V{sub oc}) = 0.727 V, and fill factor (FF) = 51%, and a power conversion efficiency = 2.02% at 100 mW/cm{sup 2} under AM1.5G illumination. The J{sub sc} and FF are sensitive to the ratio of p-DTS(FBTTh{sub 2}){sub 2}:CdSe, which is a crucial factor for the device performance.

Electrochemistry of actinide on electrochemically reduced graphene oxide: Electrocatalysis of Np(VI)O22+/Np(V)O2+ in nitric acid solution

International Nuclear Information System (INIS)

Ambolikar, Arvind S.; Guin, Saurav K.; Kasar, U.M.; Kamat, J.V.

2015-01-01

Highlights: • First report of aqueous electrochemistry of neptunium on electrochemically reduced graphene oxide (ERGNO). • First report on the electrochemical impedance spectroscopy of Np (VI) O 2 2+ /Np (V) O 2 + . • The electrochemical reversibility of Np (VI) O 2 2+ /Np (V) O 2 + redox couple improves on ERGNO compared to GC. • ERGNO shows higher sensitivity for the determination of Np compared to bare GC electrode. • The efficiency of detection of Np by ERGNO is improved by virtue of the electrocatalysis. - Abstract: Driven by the academic interest, we have studied the aqueous electrochemistry of neptunium (Np) in 1 M nitric acid solution on the electrochemically reduced graphene oxide (ERGNO) modified glassy carbon (GC) electrode. Similar to our previous experiences on the electrocatalytic action of ERGNO on the electrochemistry of uranium(VI)/uranium(IV) and plutonium(IV)/plutonium(III) redox couples, the present study confirms the robust electrocatalytic ability of ERGNO for the redox reaction of Np (VI) O 2 2+ /Np (V) O 2 + in acidic solution even at high anodic working potentials. The extent of the electrochemical reversibility of Np (VI) O 2 2+ /Np (V) O 2 + redox couple increases on ERGNO compared to the bare GC electrode. For the first time, the electron transfer reaction of Np (VI) O 2 2+ /Np (V) O 2 + redox couple is investigated by electrochemical impedance spectroscopy. The improved sensitivity as well as the lower limit of detection of Np by anodic square wave voltammetry on ERGNO compared to bare GC opens up the application of ERGNO in the nuclear science and technology.

Electrochemistry of chromium subgroup transition metal ions in an ambient temperature chloroaluminate molten salt

International Nuclear Information System (INIS)

Scheffler, T.B.

1984-01-01

The electrochemistry of several chromium subgroup transition metal solutes was studied in the basic AlCl 3 -1-methyl-3-ethylimidazolium chloride (MEIC) ionic liquid at 40.0 0 C by using stationary and rotating disk electrode voltametry, chronoamperometry, coulometry, and UV-vis spectrophotometry. Chromium(III) was present in the melt as the chloro complex [CrCl 6 ] 3- . This complex underwent as essentially irreversible reduction, apparently as a result of slow charge-transfer, to a chromium(II) species at ca. -1.08 V versus an aluminum wire immersed in 66.7 mol % melt. Similar investigations of molybdenum and tungsten were also conducted. Mechanisms are proposed to account for the results

Anthraquinone as a Redox Label for DNA: Synthesis, Enzymatic Incorporation, and Electrochemistry of Anthraquinone-Modified Nucleosides, Nucleotides, and DNA

Czech Academy of Sciences Publication Activity Database

Balintová, Jana; Pohl, Radek; Horáková Brázdilová, Petra; Vidláková, Pavlína; Havran, Luděk; Fojta, Miroslav; Hocek, Michal

2011-01-01

Roč. 17, č. 50 (2011), s. 14063-14073 ISSN 0947-6539 R&D Projects: GA MŠk(CZ) LC06035; GA MŠk LC512; GA AV ČR(CZ) IAA400040901 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : anthraquinone * DNA * electrochemistry * nucleosides * oligonucleotides Subject RIV: CC - Organic Chemistry Impact factor: 5.925, year: 2011

Potencialidades da utilização de compostos de ródio na confecção de sensores eletroquímicos: uma breve revisão

Directory of Open Access Journals (Sweden)

Gil Eric de Souza

1998-01-01

Full Text Available The electrochemistry field has increased in recent years, specially in the search for new sensors to monitor specific analyte in complex samples. In order to improve electrodes, many rhodium compounds have been used as electron mediators for novel sensors development. The most used compounds for this purpose are metal, metal complexes and some organic dyes. Rhodium complexes are known by their good catalytic properties and it could be useful in the sensor field. However, there are only a few reports, on the use of rhodium complexes in sensors and biosensors. A brief review of the electrochemistry of rhodium complexes and some discription of their properties which make those compounds suitable for development of sensor and biosensor.

Electrochemistry of a ferrocene-grafted cell-penetrating peptide

International Nuclear Information System (INIS)

Messina, Pierluca; Hallais, Géraldine; Labbé, Eric; Béranger, Marie; Chassaing, Gérard; Lavielle, Solange; Mansuy, Christelle; Buriez, Olivier

2012-01-01

A cationic cell-penetrating peptide (CPP) labeled with both a ferrocenyl (Fc) moiety and a biotin (B) was successfully synthesized and investigated by electrochemistry. This original CPP derivative noted as Fc-CPP-B could be electrochemically detected, at a micromolar concentration, at a naked gold bead electrode. The presence of a biotin tag in the Fc-CPP-B complex allowed its complexation with avidin, which was itself tethered to a thiolated self-assembled monolayer. Such an avidin-modified gold surface, characterized by atomic force microscopy (AFM), allowed the immobilization of Fc-CPP-B onto the electrode surface, which greatly enhanced its electrochemical detection. Nevertheless, under these conditions the electrogenerated ferrocenium cation could not be reduced during the backward scan, indicating its unexpected reactivity when tethered within the avidin environment. In terms of detection and redox probe regeneration the best results were obtained at a glassy carbon electrode modified with a cation-exchange polymer. Ion-exchange voltammetry, performed under these conditions, allowed the pre-concentration of the peptide at the electrode surface thanks to the net positive charge of the CPP derivative. Interestingly, the anionic character of the polymer contributed to retain the electrogenerated cation Fc + in the film so that it could be reduced back to its original neutral form during the reverse voltammetric scans.

Structural, magnetic, and electronic properties of iron selenide Fe{sub 6-7}Se{sub 8} nanoparticles obtained by thermal decomposition in high-temperature organic solvents

Energy Technology Data Exchange (ETDEWEB)

Lyubutin, I. S., E-mail: lyubutinig@mail.ru, E-mail: crlin@mail.npue.edu.tw; Funtov, K. O.; Dmitrieva, T. V.; Starchikov, S. S. [Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow 119333 (Russian Federation); Lin, Chun-Rong, E-mail: lyubutinig@mail.ru, E-mail: crlin@mail.npue.edu.tw [Department of Applied Physics, National Pingtung University of Education, Pingtung 90003, Taiwan (China); Siao, Yu-Jhan [Department of Mechanical Engineering, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan (China); Chen, Mei-Li [Department of Electro-optical Engineering, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan (China)

2014-07-28

Iron selenide nanoparticles with the NiAs-like crystal structure were synthesized by thermal decomposition of iron chloride and selenium powder in a high-temperature organic solvent. Depending on the time of the compound processing at 340 °C, the nanocrystals with monoclinic (M)-Fe{sub 3}Se{sub 4} or hexagonal (H)-Fe{sub 7}Se{sub 8} structures as well as a mixture of these two phases can be obtained. The magnetic behavior of the monoclinic and hexagonal phases is very different. The applied-field and temperature dependences of magnetization reveal a complicated transformation between ferrimagnetic (FRM) and antiferromagnetic (AFM) structures, which can be related to the spin rotation process connected with the redistribution of cation vacancies. From XRD and Mössbauer data, the 3c type superstructure of vacancy ordering was found in the hexagonal Fe{sub 7}Se{sub 8}. Redistribution of vacancies in Fe{sub 7}Se{sub 8} from random to ordered leads to the transformation of the magnetic structure from FRM to AFM. The Mössbauer data indicate that vacancies in the monoclinic Fe{sub 3}Se{sub 4} prefer to appear near the Fe{sup 3+} ions and stimulate the magnetic transition with the rotation of the Fe{sup 3+} magnetic moments. Unusually high coercive force H{sub c} was found in both (H) and (M) nanocrystals with the highest (“giant”) value of about 25 kOe in monoclinic Fe{sub 3}Se{sub 4}. This is explained by the strong surface magnetic anisotropy which is essentially larger than the core anisotropy. Such a large coercivity is rare for materials without rare earth or noble metal elements, and the Fe{sub 3}Se{sub 4}-based compounds can be the low-cost, nontoxic alternative materials for advanced magnets. In addition, an unusual effect of “switching” of magnetization in a field of 10 kOe was found in the Fe{sub 3}Se{sub 4} nanoparticles below 280 K, which can be important for applications.

Design and fabrication of anti-reflection coating on Gallium Phosphide, Zinc Selenide and Zinc Sulfide substrates for visible and infrared application

Directory of Open Access Journals (Sweden)

Mokrý P.

2013-05-01

Full Text Available Results of design and fabrication of a dual-band anti-reflection coating on a gallium phosphide (GaP, zinc selenide (ZnSe and zinc sulfide (ZnS substrates are presented. A multilayer stack structure of antireflection coatings made of zinc sulfide and yttrium fluoride (YF3 was theoretically designed for optical bands between 0.8 and 0.9 μm and between 9.5 and 10.5 μm. This stack was designed as efficient for these materials (GaP, ZnS, ZnSe together. Multilayer stack structure was deposited using thermal evaporation method. Theoretically predicted transmittance spectra were compared with transmitted spectra measured on coated substrates. Efficiency of anti-reflection coating is estimated and discrepancies are analyzed and discussed.

An aptamer-based biosensing platform for highly sensitive detection of platelet-derived growth factor via enzyme-mediated direct electrochemistry

International Nuclear Information System (INIS)

Deng Kun; Xiang Yang; Zhang Liqun; Chen Qinghai; Fu Weiling

2013-01-01

Highlights: ► Direct electrochemistry of glucose oxidase used for signal generation in aptasensor. ► Using novel nanocomposite for immobilization and signal amplification. ► Sensitive electrochemical detection of platelet-derived growth factor. - Abstract: In this work, a new label-free electrochemical aptamer-based sensor (aptasensor) was constructed for detection of platelet-derived growth factor (PDGF) based on the direct electrochemistry of glucose oxidase (GOD). For this proposed aptasensor, poly(diallyldimethylammonium chloride) (PDDA)-protected graphene-gold nanoparticles (P-Gra-GNPs) composite was firstly coated on electrode surface to form the interface with biocompatibility and huge surface area for the adsorption of GOD layer. Subsequently, gold nanoclusters (GNCs) were deposited on the surface of GOD to capture PDGF binding aptamer (PBA). Finally, GOD as a blocking reagent was employed to block the remaining active sites of the GNCs and avoid the nonspecific adsorption. With the direct electron transfer of double layer GOD membranes, the aptasensor showed excellent electrochemical response and the peak current decreased linearly with increasing logarithm of PDGF concentration from 0.005 nM to 60 nM with a relatively low limit of detection of 1.7 pM. The proposed aptasensor exhibited high specificity, good reproducibility and long-term stability, which provided a new promising technique for aptamer-based protein detection.

Influence of growth and photocatalytic properties of copper selenide (CuSe) nanoparticles using reflux condensation method

Energy Technology Data Exchange (ETDEWEB)

Sonia, S. [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046 (India); Kumar, P. Suresh [Thin Film and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore 641046 (India); Mangalaraj, D., E-mail: dmraj800@yahoo.com [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046 (India); Ponpandian, N.; Viswanathan, C. [Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046 (India)

2013-10-15

Influence of reaction conditions on the synthesis of copper selenide (CuSe) nanoparticles and their photo degradation activity is studied. Nearly monodispersed uniform size (23–44 nm) nanoparticles are synthesized by varying the reaction conditions using reflux condensation method. The obtained nanoparticles are characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and UV–visible absorption spectroscopy. The X-ray diffraction analysis of the sample shows the formation of nanoparticles with hexagonal CuSe structure. The result indicates that on increasing the reaction time from 4 to 12 h, the particle size decreases from 44 to 23 nm, but an increase in the reaction temperature increases the particle size. The calculated band gap E{sub g} is ranging from 2.34 to 3.05 eV which is blue shifted from the bulk CuSe (2.2 eV). The photocatalytic degradation efficiency of the CuSe nanoparticles on two organic dyes Methylene blue (MB) and Rhodamine-B (RhB) in aqueous solution under UV region is calculated as 76 and 87% respectively.

MOF-derived Co-doped nickel selenide/C electrocatalysts supported on Ni foam for overall water splitting

KAUST Repository

Ming, Fangwang; Liang, Hanfeng; Shi, Huanhuan; Xu, Xun; Mei, Gui; Wang, Zhoucheng

2016-01-01

It is of prime importance to develop dual-functional electrocatalysts with good activity for overall water splitting, which remains a great challenge. Herein, we report the synthesis of a Co-doped nickel selenide (a mixture of NiSe and NiSe)/C hybrid nanostructure supported on Ni foam using a metal-organic framework as the precursor. The resulting catalyst exhibits excellent catalytic activity toward the oxygen evolution reaction (OER), which only requires an overpotential of 275 mV to drive a current density of 30 mA cm. This overpotential is much lower than those reported for precious metal free OER catalysts. The hybrid is also capable of catalyzing the hydrogen evolution reaction (HER) efficiently. A current density of -10 mA cm can be achieved at 90 mV. In addition, such a hybrid nanostructure can achieve 10 and 30 mA cm at potentials of 1.6 and 1.71 V, respectively, along with good durability when functioning as both the cathode and the anode for overall water splitting in basic media.

MOF-derived Co-doped nickel selenide/C electrocatalysts supported on Ni foam for overall water splitting

KAUST Repository

Ming, Fangwang

2016-09-01

It is of prime importance to develop dual-functional electrocatalysts with good activity for overall water splitting, which remains a great challenge. Herein, we report the synthesis of a Co-doped nickel selenide (a mixture of NiSe and NiSe)/C hybrid nanostructure supported on Ni foam using a metal-organic framework as the precursor. The resulting catalyst exhibits excellent catalytic activity toward the oxygen evolution reaction (OER), which only requires an overpotential of 275 mV to drive a current density of 30 mA cm. This overpotential is much lower than those reported for precious metal free OER catalysts. The hybrid is also capable of catalyzing the hydrogen evolution reaction (HER) efficiently. A current density of -10 mA cm can be achieved at 90 mV. In addition, such a hybrid nanostructure can achieve 10 and 30 mA cm at potentials of 1.6 and 1.71 V, respectively, along with good durability when functioning as both the cathode and the anode for overall water splitting in basic media.

Direct electrochemistry of glucose oxidase and sensing glucose using a screen-printed carbon electrode modified with graphite nanosheets and zinc oxide nanoparticles

International Nuclear Information System (INIS)

Karuppiah, Chelladurai; Palanisamy, Selvakumar; Chen, Shen-Ming; Veeramani, Vediyappan; Periakaruppan, Prakash

2014-01-01

We have studied the direct electrochemistry of glucose oxidase (GOx) immobilized on electrochemically fabricated graphite nanosheets (GNs) and zinc oxide nanoparticles (ZnO) that were deposited on a screen printed carbon electrode (SPCE). The GNs/ZnO composite was characterized by using scanning electron microscopy and elemental analysis. The GOx immobilized on the modified electrode shows a well-defined redox couple at a formal potential of −0.4 V. The enhanced direct electrochemistry of GOx (compared to electrodes without ZnO or without GNs) indicates a fast electron transfer at this kind of electrode, with a heterogeneous electron transfer rate constant (Ks) of 3.75 s −1 . The fast electron transfer is attributed to the high conductivity and large edge plane defects of GNs and good conductivity of ZnO-NPs. The modified electrode displays a linear response to glucose in concentrations from 0.3 to 4.5 mM, and the sensitivity is 30.07 μA mM −1 cm −2 . The sensor exhibits a high selectivity, good repeatability and reproducibility, and long term stability. (author)

Anthraquinone as a redox label for DNA. Synthesis, enzymatic incorporation and electrochemistry of anthraquinone modified nucleosides, nucleotides and DNA

Czech Academy of Sciences Publication Activity Database

Balintová, J.; Havran, Luděk; Fojta, Miroslav; Hocek, Michal

2012-01-01

Roč. 106, - (2012), s1033-s1033 ISSN 0009-2770. [EuCheMS Chemistry Congress /4./. 26.08.2012-30.08.2012, Prague] R&D Projects: GA ČR GA203/09/0317; GA MŠk LC512; GA MŠk 1M0508; GA AV ČR(CZ) IAA400040901 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50040702 Keywords : nucleosides * oligonucleotides * electrochemistry Subject RIV: CC - Organic Chemistry

Selenide isotope generator for the Galileo Mission: copper/water axially-grooved heat pipe topical report

International Nuclear Information System (INIS)

Strazza, N.P.

1979-01-01

This report presents a summary of the major accomplishments for the development, fabrication, and testing of axially-grooved copper/water heat pipes for Selenide Isotopic Generator (SIG) applications. The early development consisted of chemical, physical, and analytical studies to define an axially-grooved tube geometry that could be successfully fabricated and provide the desired long term (up to seven years) performance is presented. Heat pipe fabrication procedures, measured performance and accelerated life testing of heat pipes S/Ns AL-5 and LT-57 conducted at B and K Engineering are discussed. S/N AL-5 was the first axially-grooved copper/water heat pipe that was fabricated with the new internal coating process for cupric oxide (CuO) and the cleaning and water preparation methods developed by Battelle Columbus Laboratories. Heat pipe S/N LT-57 was fabricated along with sixty other axially-grooved heat pipes allocated for life testing at Teledyne Energy Systems. As of June 25, 1979, heat pipes S/Ns AL-5 and LT-57 have been accelerated life tested for 13,310 and 6,292 respectively, at a nominal operating temperature of 225 0 C without any signs of thermal performance degradation

Direct electrochemistry of nitrate reductase from the fungus Neurospora crassa.

Science.gov (United States)

Kalimuthu, Palraj; Ringel, Phillip; Kruse, Tobias; Bernhardt, Paul V

2016-09-01

We report the first direct (unmediated) catalytic electrochemistry of a eukaryotic nitrate reductase (NR). NR from the filamentous fungus Neurospora crassa, is a member of the mononuclear molybdenum enzyme family and contains a Mo, heme and FAD cofactor which are involved in electron transfer from NAD(P)H to the (Mo) active site where reduction of nitrate to nitrite takes place. NR was adsorbed on an edge plane pyrolytic graphite (EPG) working electrode. Non-turnover redox responses were observed in the absence of nitrate from holo NR and three variants lacking the FAD, heme or Mo cofactor. The FAD response is due to dissociated cofactor in all cases. In the presence of nitrate, NR shows a pronounced cathodic catalytic wave with an apparent Michaelis constant (KM) of 39μM (pH7). The catalytic cathodic current increases with temperature from 5 to 35°C and an activation enthalpy of 26kJmol(-1) was determined. In spite of dissociation of the FAD cofactor, catalytically activity is maintained. Copyright © 2016. Published by Elsevier B.V.

Electrochemistry, polymers and opto-electronic devices: a combination with a future

Directory of Open Access Journals (Sweden)

De Paoli Marco-A.

2002-01-01

Full Text Available Electrochemistry came into life with the invention of the pile, by Volta in 1800. He combined different metal discs with a piece of tissue, swollen with an aqueous salt solution. The so-called Pila di Volta used a polymer for the first time in an electrochemical device and can be seen as a powerful idea to create new devices. Recently, polymers became an alternative to make thin and flexible devices. Thus, we find transparent plastic electrodes based on poly(ethylene terephtalate coated with a transition metal oxide. There are also polymer electrolytes based on complexes of inorganic salts and poly(ethylene oxide derivatives, with reasonable ionic conductivity in the absence of solvents. Finally, the electroactive polymers are efficient substitutes for the inorganic semiconductors because they can be synthetically tailored to produce the desired electronic answer. Combining these materials it is possible to assemble different types of electro-optical devices, like electrochromic, photoelectrochemical and light-emitting electrochemical cells.

Electrochemistry of immobilized particles and droplets experiments with three-phase electrodes

CERN Document Server

Scholz, Fritz; Gulaboski, Rubin; Schröder, Uwe

2014-01-01

This second edition of a successful and highly-accessed monograph has been extended by more than 100 pages. It includes an enlarged coverage of applications for materials characterization and analysis. Also a more detailed description of strategies for determining free energies of ion transfer between miscible liquids is provided. This is now possible with a "third-phase strategy" which the authors explain from theoretical and practical points of view. The book is still the only one detailing strategies for solid state electroanalysis. It also features the specific potential of the techniques to use immobilized particles (for studies of solid materials) and of immobilized droplets of immiscible liquids for the purpose of studying the three-phase electrochemistry of these liquids. This also includes studies of ion transfer between aqueous and immiscible non-aqueous liquids. The bibliography of all published papers in this field of research has been expanded from 318 to now 444 references in this second editi...

Comparison Study of Voltammetric Behavior of Muscle Relaxant Dantrolene Sodium on Silver Solid Amalgam and Bismuth Film Electrodes

Czech Academy of Sciences Publication Activity Database

Šelešovská, R.; Martinková, P.; Štěpánková, M.; Navrátil, Tomáš; Chýlková, J.

2017-01-01

Roč. 2017, č. 2017 (2017), č. článku 3627428. ISSN 2090-8865 R&D Projects: GA ČR GA17-03868S Institutional support: RVO:61388955 Keywords : performance liquid-chromatography * differential-pulse polarography * anodic-stripping voltammetry * screen-printed electrodes * organic-compounds Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 1.801, year: 2016

Comparison Study of Voltammetric Behavior of Muscle Relaxant Dantrolene Sodium on Silver Solid Amalgam and Bismuth Film Electrodes

Czech Academy of Sciences Publication Activity Database

Šelešovská, R.; Martinková, P.; Štěpánková, M.; Navrátil, Tomáš; Chýlková, J.

2017-01-01

Roč. 2017, č. 2017 (2017), č. článku 3627428. ISSN 2090-8865 R&D Projects: GA ČR GA17-03868S Institutional support: RVO:61388955 Keywords : performance liquid - chromatography * differential-pulse polarography * anodic-stripping voltammetry * screen-printed electrodes * organic-compounds Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 1.801, year: 2016

Repair of model compounds of photoinduced lesions in DNA. Electrochemical approaches; Reparation de modeles de lesions photoinduites de l'ADN. Approches electrochimiques

Energy Technology Data Exchange (ETDEWEB)

Boussicault, F

2006-09-15

The goal of this work is to better understand the repair mechanism of photoinduced lesions in DNA (cyclobutane dimers and pyrimidine (6-4) pyrimidone adducts) by photolyase redox enzymes, using tools and concepts of molecular electrochemistry. Thanks to the study of model compounds of cyclobutane lesions by cyclic voltametry, we have been able to mimic the key step of the enzymatic repair (dissociative electron transfer) and to monitor the repair of model compounds by Escherichia coli DNA photolyase. From these results, we have discussed the repair mechanism, especially the stepwise or concerted character of the process. Repair mechanism of (6-4) adducts is not known now, but a possible pathway implies an electron transfer coupled to the cleavage of two bonds in the closed form of the lesions (oxetanes). Voltammetric study of reduction and oxidation of model oxetanes and their repair by E. coli DNA photolyase gave some experimental evidence confirming the proposed mechanism and allowing a better understanding of it. (author)

USSR Report Chemistry

National Research Council Canada - National Science Library

1986-01-01

THIS REPORT CONTAINS FOREIGN MEDIA INFORMATION FROM THE USSR CONCERNING Adsorption, Alkaloids, ANALYTICAL CHEMISTRY, CATALYSIS, ELECTROCHEMISTRY, Fertilizers, INORGANIC COMPOUNDS, ORGANOPHOSPHOROUS...

Electrochemistry in light water reactors reference electrodes, measurement, corrosion and tribocorrosion issues

CERN Document Server

Bosch, R -W; Celis, Jean-Pierre

2007-01-01

There has long been a need for effective methods of measuring corrosion within light water nuclear reactors. This important volume discusses key issues surrounding the development of high temperature reference electrodes and other electrochemical techniques. The book is divided into three parts with part one reviewing the latest developments in the use of reference electrode technology in both pressurised water and boiling water reactors. Parts two and three cover different types of corrosion and tribocorrosion and ways they can be measured using such techniques as electrochemical impedance spectroscopy. Topics covered across the book include in-pile testing, modelling techniques and the tribocorrosion behaviour of stainless steel under reactor conditions. Electrochemistry in light water reactors is a valuable reference for all those concerned with corrosion problems in this key technology for the power industry. Discusses key issues surrounding the development of high temperature reference eletrodes A valuab...

Electrochemistry as a Tool for Study, Delvelopment and Promotion of Catalytic Reactions

DEFF Research Database (Denmark)

Petrushina, Irina

of Fermi level by electrochemical production of promoters, reducing or oxidizing current carriers of the catalyst support (O2-, H+, Na+). This type1 was abbreviated as EEPP. In Capters 4-7, the results of my research are given as examples of use of electrochemistry as a tool for study, promotion...... be measured and changed by polarization in electrochemical experiment. In Chapter 3 the nature of the electrochemical heterogeneous catalytic reactions is dicussed, including the new theory of electrochemical promotion. This theory is based on electrochemical change of the Fermi level of the catalyst. It also...... states that that there are two types of electrochemical promotion: First type is based on change of the Fermi level through the charge of the electric double layer (EDL) between catalyst and its support without electrochemical reaction. This effect was abbreviated as EDLE. Second type is based on change...

Facile hot-injection synthesis of stoichiometric Cu2ZnSnSe4 nanocrystals using bis(triethylsilyl) selenide.

Science.gov (United States)

Jin, Chunyu; Ramasamy, Parthiban; Kim, Jinkwon

2014-07-07

Cu2ZnSnSe4 is a prospective material as an absorber in thin film solar cells due to its many advantages including direct band gap, high absorption coefficient, low toxicity, and relative abundance (indium-free) of its elements. In this report, CZTSe nanoparticles have been synthesized by the hot-injection method using bis-(triethylsilyl)selenide [(Et3Si)2Se] as the selenium source for the first time. Energy dispersive X-ray spectroscopy (EDS) confirmed the stoichiometry of CZTSe nanoparticles. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies showed that the nanocrystals were single phase polycrystalline with their size within the range of 25-30 nm. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy measurements ruled out the existence of secondary phases such as Cu2SnSe3 and ZnSe. The effect of reaction time and precursor injection order on the formation of stoichiometric CZTSe nanoparticles has been studied by Raman spectroscopy. UV-vis-NIR data indicate that the CZTSe nanocrystals have an optical band gap of 1.59 eV, which is optimal for photovoltaic applications.

An aptamer-based biosensing platform for highly sensitive detection of platelet-derived growth factor via enzyme-mediated direct electrochemistry

Energy Technology Data Exchange (ETDEWEB)

Deng Kun; Xiang Yang; Zhang Liqun; Chen Qinghai [Laboratory of the Clinical Experimental Base of Biosensor and Microarray, Center of Molecule and Gene Diagnosis, Southwest Hospital, Third Military Medical University, Chongqing 400042 (China); Fu Weiling, E-mail: weilingfu@yahoo.com [Laboratory of the Clinical Experimental Base of Biosensor and Microarray, Center of Molecule and Gene Diagnosis, Southwest Hospital, Third Military Medical University, Chongqing 400042 (China)

2013-01-08

Highlights: Black-Right-Pointing-Pointer Direct electrochemistry of glucose oxidase used for signal generation in aptasensor. Black-Right-Pointing-Pointer Using novel nanocomposite for immobilization and signal amplification. Black-Right-Pointing-Pointer Sensitive electrochemical detection of platelet-derived growth factor. - Abstract: In this work, a new label-free electrochemical aptamer-based sensor (aptasensor) was constructed for detection of platelet-derived growth factor (PDGF) based on the direct electrochemistry of glucose oxidase (GOD). For this proposed aptasensor, poly(diallyldimethylammonium chloride) (PDDA)-protected graphene-gold nanoparticles (P-Gra-GNPs) composite was firstly coated on electrode surface to form the interface with biocompatibility and huge surface area for the adsorption of GOD layer. Subsequently, gold nanoclusters (GNCs) were deposited on the surface of GOD to capture PDGF binding aptamer (PBA). Finally, GOD as a blocking reagent was employed to block the remaining active sites of the GNCs and avoid the nonspecific adsorption. With the direct electron transfer of double layer GOD membranes, the aptasensor showed excellent electrochemical response and the peak current decreased linearly with increasing logarithm of PDGF concentration from 0.005 nM to 60 nM with a relatively low limit of detection of 1.7 pM. The proposed aptasensor exhibited high specificity, good reproducibility and long-term stability, which provided a new promising technique for aptamer-based protein detection.

Investigation of Electronic and Opto-Electronic Properties of Two-Dimensional (2D) Layers of Copper Indium Selenide Field Effect Transistors

Science.gov (United States)

Patil, Prasanna Dnyaneshwar

Investigations performed in order to understand the electronic and optoelectronic properties of field effect transistors based on few layers of 2D Copper Indium Selenide (CuIn7Se11) are reported. In general, field effect transistors (FETs), electric double layer field effect transistors (EDL-FETs), and photodetectors are crucial part of several electronics based applications such as tele-communication, bio-sensing, and opto-electronic industry. After the discovery of graphene, several 2D semiconductor materials like TMDs (MoS2, WS2, and MoSe2 etc.), group III-VI materials (InSe, GaSe, and SnS2 etc.) are being studied rigorously in order to develop them as components in next generation FETs. Traditionally, thin films of ternary system of Copper Indium Selenide have been extensively studied and used in optoelectronics industry as photoactive component in solar cells. Thus, it is expected that atomically thin 2D layered structure of Copper Indium Selenide can have optical properties that could potentially be more advantageous than its thin film counterpart and could find use for developing next generation nano devices with utility in opto/nano electronics. Field effect transistors were fabricated using few-layers of CuIn7Se11 flakes, which were mechanically exfoliated from bulk crystals grown using chemical vapor transport technique. Our FET transport characterization measurements indicate n-type behavior with electron field effect mobility microFE ≈ 36 cm2 V-1 s-1 at room temperature when Silicon dioxide (SiO2) is used as a back gate. We found that in such back gated field effect transistor an on/off ratio of 104 and a subthreshold swing ≈ 1 V/dec can be obtained. Our investigations further indicate that Electronic performance of these materials can be increased significantly when gated from top using an ionic liquid electrolyte [1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6)]. We found that electron field effect mobility microFE can be increased from

UV-Vis-NIR spectroelectrochemical study of tetrathiorhenate-bridged diruthenium complexes

Czech Academy of Sciences Publication Activity Database

Grupp, A.; Fiedler, Jan; Kaim, W.

2015-01-01

Roč. 86, SI (2015), s. 71-75 ISSN 0277-5387 R&D Projects: GA MŠk LD14129 Institutional support: RVO:61388955 Keywords : redox reactions * rhenium compound * ruthenium compound Subject RIV: CG - Electrochemistry Impact factor: 2.108, year: 2015

The Institute of Radiochemistry, University of Liege, (Sart-Tilman), Belgium

International Nuclear Information System (INIS)

Duyckaerts, G.

1977-01-01

The Institute of Radiochemistry, erected in the new Sart-Tilman campus of the University of Liege has been especially planned and equipped for research on actinide chemistry. The two-floor building is well adapted for work in glove-boxes and well ventilated hoods with highly radioactive α-emitters. For the last ten years, research has been carried out in the following directions: synthesis and structural analysis of actinide compounds, thermodynamic evaluations on actinide compounds by microcalorimetry, electrochemistry of actinides in fused salts, redox properties of actinides in fused salts by absorption spectrophotometry, solution chemistry of actinides by solvent extraction, ion exchange and electrochemistry. (T.G.)

Synthesis, characterization, and anomalous dielectric and conductivity performance of one-dimensional (bdaH)InSe2 (bda = 1,4-butanediamine)

International Nuclear Information System (INIS)

Du, Ke-Zhao; Hu, Wan-Biao; Hu, Bing; Guan, Xiang-Feng; Huang, Xiao-Ying

2011-01-01

Graphical abstract: Anomalous dielectric and conductivity performance have been observed in the organic-containing indium selenide (bdaH)InSe 2 , which are attributed to the water molecules existing in the crystal boundary rather than phase transition. Highlights: → The title compound is the first example of organic-containing one-dimensional indium selenide. → The anomalous dielectric peak is attributed to water molecules in crystal boundary. → The inorganic and organic components of the title compound are connected via hydrogen bonding to form a supramolecular three-dimensional network. -- Abstract: A new indium selenide, namely (bdaH)InSe 2 (1) (bda = 1,4-butanediamine) has been solvothermally synthesized and structurally characterized. It belongs to the non-centrosymmetric space group Fdd2. Its structure features an infinite one-dimensional anionic chain of [InSe 2 ] n n- with monoprotonated [bdaH] + as charge compensating cation. The organic [bdaH] + cations are joined into a supramolecular one-dimensional chain via N-H...N hydrogen bonding, which further interacts with the inorganic chain via N-H...Se and C-H...Se hydrogen bonding, forming a supramolecular three-dimensional network. Based on such a well-defined structure, the thermal stability, optical, conductivity, and dielectric properties were systematically investigated, showing that dielectric constant, as well as conductivity, had a hump at about 95 o C, which could be attributed to water molecules in the crystal boundary.

Stereoisomeric products of electrochemical reduction of heterocyclic Fischer aminocarbene Cr(0) complexes. Development of the electrochemistry-mass spectrometry tandem approach using biphasic (acetonitrile-hexane) preparative electrolysis

Czech Academy of Sciences Publication Activity Database

Metelková, R.; Hoskovcová, I.; Polášek, Miroslav; Urban, Jiří; David, T.; Ludvík, Jiří

2015-01-01

Roč. 162, APR 2015 (2015), s. 17-23 ISSN 0013-4686 R&D Projects: GA ČR GAP206/11/0727 Institutional support: RVO:61388955 Keywords : Fischer aminocarbene complexes biphasic electrolysis * EC-MS * HPLC-NMR Subject RIV: CG - Electrochemistry Impact factor: 4.803, year: 2015

Structural and electrochemical analysis of chemically synthesized microcubic architectured lead selenide thin films

Science.gov (United States)

Bhat, T. S.; Shinde, A. V.; Devan, R. S.; Teli, A. M.; Ma, Y. R.; Kim, J. H.; Patil, P. S.

2018-01-01

The present work deals with the synthesis of lead selenide (PbSe) thin films by simple and cost-effective chemical bath deposition method with variation in deposition time. The structural, morphological, and electrochemical properties of as-deposited thin films were examined using characterization techniques such as X-ray diffraction spectroscopy (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy. XRD reveals formation of rock salt phase cubic structured PbSe. FE-SEM images show the formation of microcubic structured morphology. The existence of the PbSe is confirmed from the XPS analysis. On the other hand, CV curves show four reaction peaks corresponding to oxidation [PbSe and Pb(OH)2] and reduction (PbO2 and Pb(OH)2) at the surface of PbSe thin films. The PbSe:2 sample deposited for 80 min. shows maximum specific capacitance of 454 ± 5 F g- 1 obtained at 0.25 mA cm- 2 current density. The maximum energy density of 69 Wh kg- 1 was showed by PbSe:2 electrode with a power density of 1077 W kg- 1. Furthermore, electrochemical impedance studies of PbSe:2 thin film show 80 ± 3% cycling stability even after 500 CV cycles. Such results show the importance of microcubic structured PbSe thin film as an anode in supercapacitor devices.

A transparent nickel selenide counter electrode for high efficient dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Dong, Jia; Wu, Jihuai, E-mail: jhwu@hqu.edu.cn; Jia, Jinbiao; Ge, Jinhua; Bao, Quanlin; Wang, Chaotao; Fan, Leqing

2017-04-15

Highlights: • Ni{sub 0.85}Se was obtained by hydrothermal way and the film was gained by spin-coating. • Ni{sub 0.85}Se film has good conductivity and excellent electrocatalytic activity. • DSSC based on transparent Ni{sub 0.85}Se counter electrode obtains PCE of 8.96%. • The PCE reaches 10.76% when putting a mirror under Ni{sub 0.85}Se counter electrode. - Abstract: Nickel selenide (Ni{sub 0.85}Se) was synthesized by a facile one-step hydrothermal reaction and Ni{sub 0.85}Se film was prepared by spin-coating Ni{sub 0.85}Se ink on FTO and used as counter electrode (CE) in dye-sensitized solar cells (DSSC). The Ni{sub 0.85}Se CEs not only show high transmittance in visible range, but also possess remarkable electrocatalytic activity toward I{sup −}/I{sub 3}{sup −}. The electrocatalytic ability of Ni{sub 0.85}Se films was verified by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization curves. The DSSC using Ni{sub 0.85}Se CE exhibits a power conversion efficiency (PCE) of 8.96%, while the DSSC consisting of sputtered Pt CE only exhibits a PCE of 8.15%. When adding a mirror under Ni{sub 0.85}Se CE, the resultant DSSC exhibits a PCE of 10.76%, which exceeds that of a DSSC based on sputtered Pt CE (8.44%) by 27.49%.

Iron selenide films by aerosol assisted chemical vapor deposition from single source organometallic precursor in the presence of surfactants

Energy Technology Data Exchange (ETDEWEB)

Hussain, Raja Azadar [Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Badshah, Amin, E-mail: aminbadshah@yahoo.com [Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Younis, Adnan [School of Materials Science and Engineering, University of New South Wales, Sydney 2052, NSW (Australia); Khan, Malik Dilshad [Department of Chemistry, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Akhtar, Javeed [Department of Physics, COMSATS Institute of Information Technology, Park Road, Chak Shahzad, Islamabad (Pakistan)

2014-09-30

This article presents the synthesis and characterization (multinuclear nuclear magnetic resonance, Fourier transform infrared spectroscopy, carbon–hydrogen–nitrogen–sulfur analyzer, atomic absorption spectrometry and thermogravimetric analysis) of a single source organometallic precursor namely 1-acetyl-3-(4-ferrocenylphenyl)selenourea for the fabrication of iron selenide (FeSe) films on glass substrates using aerosol assisted chemical vapor deposition (AACVD). The changes in the morphologies of the films have been monitored by the use of two different surfactants i.e. triton X-100 and tetraoctylphosphonium bromide during AACVD. The role of surfactant has been evaluated by examining the interaction of the surfactants with the precursor by using UV–vis spectroscopy and cyclic voltammetry. The fabricated FeSe films have been characterized with powder X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. - Highlights: • Ferrocene incorporated selenourea (FIS) has been synthesized and characterized. • FeSe thin films have been fabricated from FIS. • Mechanism of film growth was studied with cyclic voltammetry and UV–vis spectroscopy.

Transparent nickel selenide used as counter electrode in high efficient dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Jia, Jinbiao; Wu, Jihuai, E-mail: jhwu@hqu.edu.cn; Tu, Yongguang; Huo, Jinghao; Zheng, Min; Lin, Jianming

2015-08-15

Highlights: • A transparent Ni{sub 0.85}Se is prepared by a facile solvothermal reaction. • Ni{sub 0.85}Se electrode has better electrocatalytic activity than Pt electrode. • DSSC with Ni{sub 0.85}Se electrode obtains efficiency of 8.88%, higher than DSSC with Pt. • DSSC with Ni{sub 0.85}Se/mirror electrode achieves an efficiency of 10.19%. - Abstract: A transparent nickel selenide (Ni{sub 0.85}Se) is prepared by a facile solvothermal reaction and used as an efficient Pt-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). Field emission scanning electron microscopy observes that the as-prepared Ni{sub 0.85}Se possesses porous structure. Cyclic voltammogram measurement indicates that Ni{sub 0.85}Se electrode has larger current density than Pt electrode. Electrochemical impedance spectroscopy shows that the Ni{sub 0.85}Se electrode has lower charge-transfer resistance than Pt electrode. Under simulated solar light irradiation with intensity of 100 mW cm{sup −2} (AM 1.5), the DSSC based on the Ni{sub 0.85}Se CE achieves a power conversion efficiency (PCE) of 8.88%, which is higher than the solar cell based on Pt CE (8.13%). Based on the transparency of Ni{sub 0.85}Se, the DSSC with Ni{sub 0.85}Se/mirror achieves a PCE of 10.19%.

Coexistence of multiphase superconductivity and ferromagnetism in lithiated iron selenide hydroxide [(L i1 -xF ex) OH ]FeSe

Science.gov (United States)

Urban, Christian; Valmianski, Ilya; Pachmayr, Ursula; Basaran, Ali C.; Johrendt, Dirk; Schuller, Ivan K.

2018-01-01

We present experimental evidence for (a) multiphase superconductivity and (b) coexistence of magnetism and superconductivity in a single structural phase of lithiated iron selenide hydroxide [(L i1 -xF ex )OH]FeSe. Magnetic field modulated microwave spectroscopy data confirms superconductivity with at least two distinct transition temperatures attributed to well-defined superconducting phases at TSC 1=40 ±2 K and TSC 2=35 ±2 K. Magnetometry data for the upper critical fields reveal a change in the magnetic order (TM=12 K) below TSC 1 and TSC 2 that is consistent with ferromagnetism. This occurs because the superconducting coherence length is much smaller than the structural coherence length, allowing for several different electronic and magnetic states on a single crystallite. The results give insight into the physics of complex multinary materials, where several phenomena governed by different characteristic length scales coexist.

Electrochemistry of moexipril: experimental and computational approach and voltammetric determination.

Science.gov (United States)

Taşdemir, Hüdai I; Kiliç, E

2014-09-01

The electrochemistry of moexipril (MOE) was studied by electrochemical methods with theoretical calculations performed at B3LYP/6-31 + G (d)//AM1. Cyclic voltammetric studies were carried out based on a reversible and adsorption-controlled reduction peak at -1.35 V on a hanging mercury drop electrode (HMDE). Concurrently irreversible diffusion-controlled oxidation peak at 1.15 V on glassy carbon electrode (GCE) was also employed. Potential values are according to Ag/AgCI, (3.0 M KCI) and measurements were performed in Britton-Robinson buffer of pH 5.5. Tentative electrode mechanisms were proposed according to experimental results and ab-initio calculations. Square-wave adsorptive stripping voltammetric methods have been developed and validated for quantification of MOE in pharmaceutical preparations. Linear working range was established as 0.03-1.35 microM for HMDE and 0.2-20.0 microM for GCE. Limit of quantification (LOQ) was calculated to be 0.032 and 0.47 microM for HMDE and GCE, respectively. Methods were successfully applied to assay the drug in tablets by calibration and standard addition methods with good recoveries between 97.1% and 106.2% having relative standard deviation less than 10%.

Ce3+ 5d-centroid shift and vacuum referred 4f-electron binding energies of all lanthanide impurities in 150 different compounds

International Nuclear Information System (INIS)

Dorenbos, Pieter

2013-01-01

A review on the wavelengths of all five 4f–5d transitions for Ce 3+ in about 150 different inorganic compounds (fluorides, chlorides, bromides, iodides, oxides, sulfides, selenides, nitrides) is presented. It provides data on the centroid shift and the crystal field splitting of the 5d-configuration which are then used to estimate the Eu 2+ inter 4f-electron Coulomb repulsion energy U(6,A) in compound A. The four semi-empirical models (the redshift model, the centroid shift model, the charge transfer model, and the chemical shift model) on lanthanide levels that were developed past 12 years are briefly reviewed. It will be demonstrated how those models together with the collected data of this work and elsewhere can be united to construct schemes that contain the binding energy of electrons in the 4f and 5d states for each divalent and each trivalent lanthanide ion relative to the vacuum energy. As example the vacuum referred binding energy schemes for LaF 3 and La 2 O 3 will be constructed. - Highlights: ► An compilation on all five Ce 3+ 4f–5d energies in 150 inorganic compounds is presented. ► The relationship between the 5d centroid shift and host cation electronegativity id demonstrated. ► The electronic structure scheme of the lanthanides in La 2 O 3 and LaF 3 is presented.

On the importance of identifying, characterizing, and predicting fundamental phenomena towards microbial electrochemistry applications.

Science.gov (United States)

Torres, César Iván

2014-06-01

The development of microbial electrochemistry research toward technological applications has increased significantly in the past years, leading to many process configurations. This short review focuses on the need to identify and characterize the fundamental phenomena that control the performance of microbial electrochemical cells (MXCs). Specifically, it discusses the importance of recent efforts to discover and characterize novel microorganisms for MXC applications, as well as recent developments to understand transport limitations in MXCs. As we increase our understanding of how MXCs operate, it is imperative to continue modeling efforts in order to effectively predict their performance, design efficient MXC technologies, and implement them commercially. Thus, the success of MXC technologies largely depends on the path of identifying, understanding, and predicting fundamental phenomena that determine MXC performance. Copyright © 2013 Elsevier Ltd. All rights reserved.

The oxidative decomposition of natural bioactive compound rhamnetin

Czech Academy of Sciences Publication Activity Database

Ramešová, Šárka; Degano, I.; Sokolová, Romana

2017-01-01

Roč. 788, MAR 2017 (2017), s. 125-130 ISSN 1572-6657 Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR M200401201 Program:M Institutional support: RVO:61388955 Keywords : oxidation * flavonoids * cyclic voltammetry Subject RIV: CG - Electrochemistry OBOR OECD: Analytical chemistry Impact factor: 3.012, year: 2016

Diagnostic radiopharmaceuticals for localization in target tissues exhibiting a regional pH shift relative to surrounding tissues

International Nuclear Information System (INIS)

Blau, M.; Kung, H.F.

1985-01-01

Diagnostic radiopharmaceutical compounds are provided which are capable of entering a target tissue or a target organ by passive diffusion through cell walls and which are effectively accumulated and retained within the target tissue or organ due to a regional pH shift. Such compounds are desirably readily accessible synthetically using readily available radionuclides. The compound comprises a radioactive isotope of an element in chemical combination with at least one amine group and preferably with at least two secondary or tertiary amine groups. The radioactive element is an element other than iodine emitting gamma ray, x-ray or positron radiation. When the element is a gamma ray emitting isotope, at least 75 percent of the number of emissions is emitted at energies of between 80 and 400 keV. The half-life of the isotope is usually between two minutes and 15 days. The compound has acid-base characteristics such that the state of ionization of the compound at the pH of the body is significantly different and usually less than its state of ionization at the intracellular pH of the target tissue. The compound has such lipid solubility characteristics that it is capable of ready penetration through cell walls, but within cells its lipid solubility is substantially decreased, whereby the ability of the compound to leave the target tissue is substantially diminished. Specific data relevant to di-beta-(piperidinoethyl)-selenide and di-beta-(morpholinoethyl)-selenide in rat brains are presented

Engineering phase transformation of cobalt selenide in carbon cages and the phases’ bifunctional electrocatalytic activity for water splitting

Science.gov (United States)

Gao, Jiaojiao; Liu, Li; Qiu, Hua-Jun; Wang, Yu

2017-08-01

Using Co-based metal-organic frameworks as the precursor, we synthesized cobalt selenide (CoSe2) nanoparticles imbedded in carbon cages. By simply controlling the annealing conditions, phase transformation of CoSe2 from the orthorhombic phase to the cubic phase has been realized. Benefitting from the metallic character, the cubic phase CoSe2 shows greatly enhanced electrocatalytic activity for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). The as-prepared cubic phase CoSe2 electrode possesses onset overpotentials of 43 and 200 mV, and Tafel slopes of 51 and 83 mV dec-1 for HER and OER, respectively, which are remarkably superior to that of the orthorhombic phase CoSe2 catalyst and comparable to those of commercial noble-metal catalysts. In addition, the cubic phase CoSe2 electrode also demonstrates excellent stability after long-term operations. Our work not only provides a high performance catalyst for water splitting, but also introduces a new route to the design of a highly efficient catalyst by phase transformation.

Study on tribological and electrochemistry properties of metal materials in H2O2 solutions

Science.gov (United States)

Yuan, Chengqing; Yu, Li; Li, Jian; Yan, Xinping

2012-03-01

Hydrogen peroxide (H2O2) is a kind of ideal green propellant. It is crucial to study the wear behavior and failure modes of the metal materials under the strong oxidizing environment of H2O2. This study aims to investigate the wear of rubbing pairs of 2Cr13 stainless steel against 1045 metal in H2O2 solutions, which has a great effect on wear, the decomposition and damage mechanism of materials. The comparison analysis of the friction coefficients, wear mass loss, worn surface topographies and current densities was conducted under different concentrations of H2O2 solutions. There were significant differences in the tribological and electrochemistry properties of the rubbing pairs in different H2O2 solutions.

The edge- and basal-plane-specific electrochemistry of a single-layer graphene sheet

Science.gov (United States)

Yuan, Wenjing; Zhou, Yu; Li, Yingru; Li, Chun; Peng, Hailin; Zhang, Jin; Liu, Zhongfan; Dai, Liming; Shi, Gaoquan

2013-01-01

Graphene has a unique atom-thick two-dimensional structure and excellent properties, making it attractive for a variety of electrochemical applications, including electrosynthesis, electrochemical sensors or electrocatalysis, and energy conversion and storage. However, the electrochemistry of single-layer graphene has not yet been well understood, possibly due to the technical difficulties in handling individual graphene sheet. Here, we report the electrochemical behavior at single-layer graphene-based electrodes, comparing the basal plane of graphene to its edge. The graphene edge showed 4 orders of magnitude higher specific capacitance, much faster electron transfer rate and stronger electrocatalytic activity than those of graphene basal plane. A convergent diffusion effect was observed at the sub-nanometer thick graphene edge-electrode to accelerate the electrochemical reactions. Coupling with the high conductivity of a high-quality graphene basal plane, graphene edge is an ideal electrode for electrocatalysis and for the storage of capacitive charges. PMID:23896697

Analysis on the Performance of Copper Indium Gallium Selenide (CIGS Based Photovoltaic Thermal

Directory of Open Access Journals (Sweden)

Zulkepli Afzam

2016-01-01

Full Text Available This paper deals with the efficiency improvement of Copper Indium Gallium Selenide (CIGS Photovoltaic (PV and also solar thermal collector. Photovoltaic thermal (PV/T can improve overall efficiency for PV and also solve the problem of limited roof space at urban area. Objective of this study is to clarify the effect of mass flow rate on the efficiency of the PV/T system. A CIGS solar cell is used with rated output power 65 W and 1.18 m2 of area. 4 set of experiments were carried out, which were: thermal collector with 0.12 kg/s flow rate, PV/T with 0.12 kg/s flow rate, PV/T with 0.09 kg/s flow rate and PV. It was found that PV/T with 0.12 kg/s flow rate had the highest electrical efficiency, 2.92 %. PV/T with 0.09 kg/s flow rate had the lowest electrical efficiency, 2.68 %. It also had 2 % higher overall efficiency. The efficiency gained is low due to several factors. The rated output power of the PV is low for the area of 1.18 m2. The packing factor of the PV also need to be considered as it may not be operated at the optimal packing factor. Furthermore, aluminium sheet of the PV may affect the PV temperature due to high thermal conductivity. Further study on more values of mass flow rate and also other parameters that affect the efficiency of the PV/T is necessary.

Synthesis, structure and electrochemistry of cationic diruthenium complexes of the type [(N-N)2Ru2(CO)2(.mu.-OOCFc)]+ containing a ferrocenecarboxylato bridge and two chelating aromatic diimine ligands

Czech Academy of Sciences Publication Activity Database

Auzias, M.; Therrien, B.; Süss-Fink, G.; Štěpnička, P.; Ludvík, Jiří

2007-01-01

Roč. 692, č. 4 (2007), s. 755-760 ISSN 0022-328X Institutional research plan: CEZ:AV0Z40400503 Keywords : carbonyl ligands * carboxylato ligands * ferrocenyl substituents * diimine ligands Subject RIV: CG - Electrochemistry Impact factor: 2.168, year: 2007

Electrochemistry of Pt (100) in alkaline media: A voltammetric study

Science.gov (United States)

van der Vliet, Dennis F.; Koper, Marc T. M.

2010-10-01

Pt (100) is one of the fcc metal surface planes that reconstruct upon annealing at high temperatures. The state of the surface is important in electrochemistry, in order to correlate catalytic behavior with surface structure. Therefore, the behavior of single crystalline Pt (100) in alkaline media was investigated, with particular attention paid to surface long-range order. It was found that, in line with previous results, the manner of cooling the crystal after annealing influenced the state of surface significantly, with a profound effect on blank cyclic voltammetry as well as on carbon monoxide oxidation. Different ratios of inert and reductive gases were used to see if an optimal mixture could be obtained. Using air, argon, hydrogen, CO, and combinations of these gases gave rise to different states of the surface, with clear observable differences in blank voltammetric behavior and CO stripping. Also, the effect of alkali-metal cations and bromide on the blank and CO stripping voltammetry was investigated. Our main conclusion is that cooling in a carbon monoxide containing gas gives a clean, almost defect-free surface with long-range 1 × 1 symmetry. A similar surface can also be prepared with a hydrogen-containing cooling gas, but the content of hydrogen in that stream is critical.

Synthesis, characterization, and anomalous dielectric and conductivity performance of one-dimensional (bdaH)InSe{sub 2} (bda = 1,4-butanediamine)

Energy Technology Data Exchange (ETDEWEB)

Du, Ke-Zhao; Hu, Wan-Biao [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, The Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Hu, Bing; Guan, Xiang-Feng [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, The Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Huang, Xiao-Ying, E-mail: xyhuang@fjirsm.ac.cn [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, The Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

2011-11-15

Graphical abstract: Anomalous dielectric and conductivity performance have been observed in the organic-containing indium selenide (bdaH)InSe{sub 2}, which are attributed to the water molecules existing in the crystal boundary rather than phase transition. Highlights: {yields} The title compound is the first example of organic-containing one-dimensional indium selenide. {yields} The anomalous dielectric peak is attributed to water molecules in crystal boundary. {yields} The inorganic and organic components of the title compound are connected via hydrogen bonding to form a supramolecular three-dimensional network. -- Abstract: A new indium selenide, namely (bdaH)InSe{sub 2} (1) (bda = 1,4-butanediamine) has been solvothermally synthesized and structurally characterized. It belongs to the non-centrosymmetric space group Fdd2. Its structure features an infinite one-dimensional anionic chain of [InSe{sub 2}]{sub n}{sup n-} with monoprotonated [bdaH]{sup +} as charge compensating cation. The organic [bdaH]{sup +} cations are joined into a supramolecular one-dimensional chain via N-H...N hydrogen bonding, which further interacts with the inorganic chain via N-H...Se and C-H...Se hydrogen bonding, forming a supramolecular three-dimensional network. Based on such a well-defined structure, the thermal stability, optical, conductivity, and dielectric properties were systematically investigated, showing that dielectric constant, as well as conductivity, had a hump at about 95 {sup o}C, which could be attributed to water molecules in the crystal boundary.

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

Science.gov (United States)

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

2014-06-01

Nitrogen-doped graphene (NG) was synthesized and used for the investigation on direct electrochemistry of hemoglobin (Hb) with a carbon ionic liquid electrode as the substrate electrode. Due to specific characteristics of NG such as excellent electrocatalytic property and large surface area, direct electron transfer of Hb was realized with enhanced electrochemical responses appearing. Electrochemical behaviors of Hb on the NG modified electrode were carefully investigated with the electrochemical parameters calculated. The Hb modified electrode exhibited excellent electrocatalytic reduction activity toward different substrates, such as trichloroacetic acid and H2O2, with wider dynamic range and lower detection limit. These findings show that NG can be used for the preparation of chemically modified electrodes with improved performance and has potential applications in electrochemical sensing. Copyright © 2014 Elsevier B.V. All rights reserved.

Fabrication of graphene-platinum nanocomposite for the direct electrochemistry and electrocatalysis of myoglobin.

Science.gov (United States)

Sun, Wei; Li, Linfang; Lei, Bingxin; Li, Tongtong; Ju, Xiaomei; Wang, Xiuzheng; Li, Guangjiu; Sun, Zhenfan

2013-05-01

In this paper a platinum (Pt) nanoparticle decorated graphene (GR) nanosheet was synthesized and used for the investigation on direct electrochemistry of myoglobin (Mb). By integrating GR-Pt nanocomposite with Mb on the surface of carbon ionic liquid electrode (CILE), a new electrochemical biosensor was fabricated. UV-Vis absorption and FT-IR spectra indicated that Mb remained its native structure in the nanocomposite film. Electrochemical behaviors of Nafion/Mb-GR-Pt/CILE were investigated with a pair of well-defined redox peak appeared, which indicated that direct electron transfer of Mb was realized on the underlying electrode with the usage of the GR-Pt nanocomposite. The fabricated electrode showed good electrocatalytic activity to the reduction of trichloroacetic acid in the linear range from 0.9 to 9.0 mmol/L with the detection limit as 0.32 mmol/L (3σ), which showed potential application for fabricating novel electrochemical biosensors and bioelectronic devices. Copyright © 2012 Elsevier B.V. All rights reserved.

Glucose oxidase-graphene-chitosan modified electrode for direct electrochemistry and glucose sensing

International Nuclear Information System (INIS)

Kang, Xinhuang; Wang, Jun; Wu, Hong; Aksay, Ilhan A.; Liu, Jun; Lin, Yuehe

2009-01-01

Direct electrochemistry of a glucose oxidase (GOD)/graphene/chitosan nanocomposite was studied. The immobilized enzyme retains its bioactivity, exhibits a surface confined, reversible two-proton and two-electron transfer reaction, and has good stability, activity and a fast heterogeneous electron transfer rate with the rate constant (k s ) of 2.83 s -1 . A much higher enzyme loading (1.12 x 10 -9 mol/cm 2 ) is obtained as compared to the bare glass carbon surface. This GOD/graphene/chitosan nanocomposite film can be used for sensitive detection of glucose. The biosensor exhibits a wider linearity range from 0.08 mM to 12 mM glucose with a detection limit of 0.02 mM and much higher sensitivity (37.93 (micro)A mM -1 cm -2 ) as compared with other nanostructured supports. The excellent performance of the biosensor is attributed to large surface-to-volume ratio and high conductivity of graphene, and good biocompatibility of chitosan, which enhances the enzyme absorption and promotes direct electron transfer between redox enzymes and the surface of electrodes.

The Microscale Synthesis and Electrochemistry of Low-Valent Mononuclear Complexes (h3-C3H5)Fe(CO)3 X (X = I, Br, Cl)

Science.gov (United States)

Mocellin, Enrico; Russell, Richard; Ravera, Mauro

1998-06-01

The experimental content of this paper will appeal to pedagogues and students who might be looking for new ideas that have an element of challenge. By combining experimental procedures which place microscale, chemical synthesis, and an inclusive, unified, product characterization in perspective, we have afforded the student the scope to obtain progressive, disciplined results and the opportunity to discuss these in the subsequent reporting. By this process, it is our experience that the students often identify with the practical work that is being undertaken, and they develop considerable empathy during their contribution to the "discovery" process that this laboratory program offers. The experimental work can be abbreviated to a single compound, subdivided into synthesis or electrochemistry, or extended to macroscale and other instrumental techniques of characterization, thus offering opportunities to accommodate time constraints, class results combination and discussion, and individual student enthusiasm. We believe that having to accept and/or constructively criticize sequential experimental results, collected by fellow students, mimics more realistically the practice of chemistry at the workplace and can build enthusiasm and elicit contagious fellowship from the class. All of these aspects can simply be achieved by utilizing the listed journals and references therein. Most importantly, it affords the students the opportunity to extricate themselves as innocent bystanders from the conventional "single experiment" practical laboratory to a path of practice and achievement in the scientific method.

Manhattan Project Technical Series: The Chemistry of Uranium (I)

International Nuclear Information System (INIS)

Rabinowitch, E. I.; Katz, J. J.

1947-01-01

This constitutes Chapters 11 through 16, inclusive, of the Survey Volume on Uranium Chemistry prepared for the Manhattan Project Technical Series. Chapters are titled: Uranium Oxides, Sulfides, Selenides, and Tellurides; The Non-Volatile Fluorides of Uranium; Uranium Hexafluoride; Uranium-Chlorine Compounds; Bromides, Iodides, and Pseudo-Halides of Uranium; and Oxyhalides of Uranium.

Manhattan Project Technical Series: The Chemistry of Uranium (I)

Energy Technology Data Exchange (ETDEWEB)

Rabinowitch, E. I. [Argonne National Lab. (ANL), Argonne, IL (United States); Katz, J. J. [Argonne National Lab. (ANL), Argonne, IL (United States)

1947-03-10

This constitutes Chapters 11 through 16, inclusive, of the Survey Volume on Uranium Chemistry prepared for the Manhattan Project Technical Series. Chapters are titled: Uranium Oxides, Sulfides, Selenides, and Tellurides; The Non-Volatile Fluorides of Uranium; Uranium Hexafluoride; Uranium-Chlorine Compounds; Bromides, Iodides, and Pseudo-Halides of Uranium; and Oxyhalides of Uranium.

Inherent Electrochemistry and Charge Transfer Properties of Few-Layer Two Dimensional Ti3C2Tx MXene

KAUST Repository

Nayak, Pranati

2018-05-25

We report the effect of Ti3C2Tx MXene flake thickness on its inherent electrochemistry and heterogeneous charge transfer characteristics. It is shown that the Ti3C2Tx undergoes irreversible oxidation in the positive potential window, which strongly depends on the flake thickness and pH of the electrolyte. Few-layer Ti3C2Tx exhibits faster electron transfer kinetics (k0=0.09533 cm/s) with Fe(CN)64−/3− redox mediator compared to multi-layer Ti3C2Tx (k0= 0.00503 cm/s). In addition, few-layer free standing Ti3C2Tx film electrode remains intact after enduring irreversible oxidation.

Inherent Electrochemistry and Charge Transfer Properties of Few-Layer Two Dimensional Ti3C2Tx MXene

KAUST Repository

Nayak, Pranati; Jiang, Qiu; Mohanraman, Rajeshkumar; Anjum, Dalaver H.; Hedhili, Mohamed N.; Alshareef, Husam N.

2018-01-01

We report the effect of Ti3C2Tx MXene flake thickness on its inherent electrochemistry and heterogeneous charge transfer characteristics. It is shown that the Ti3C2Tx undergoes irreversible oxidation in the positive potential window, which strongly depends on the flake thickness and pH of the electrolyte. Few-layer Ti3C2Tx exhibits faster electron transfer kinetics (k0=0.09533 cm/s) with Fe(CN)64−/3− redox mediator compared to multi-layer Ti3C2Tx (k0= 0.00503 cm/s). In addition, few-layer free standing Ti3C2Tx film electrode remains intact after enduring irreversible oxidation.

Structure data of elements and intermetallic phases. SubVol. B. Sulfides, selenides, tellurides. Pt. 1. Ag-Al-Cd-S. Cu-Te-Yb

Energy Technology Data Exchange (ETDEWEB)

Hellwege, K H; Hellwege, A M [eds.; Eisenmann, B; Schaefer, H

1986-01-01

Volume III/14 'Structure data of elements and intermetallic phases' is a supplement to and extension of Volume III/6. Since the publication of III/6 in 1971 (considering original papers up to 1967), the amount of new information for these substances has increased rapidly. Therefore the data had to be divided into several parts. The first part, III/14b1, is presented herewith. In Volume III/6, simple sulfides, selenides and tellurides were treated together with the intermetallic phases. The data are compiled in the same way as in III/6: for each substance the space group, lattice constants, their dependence on temperature and pressure, and other information is listed in the tables. In several cases, mostly for solid solutions, diagrams are given which are added in a separate chapter. Original papers containing a complete structure analysis are referred to in the tables. (orig./GSCH).

Electrochemistry and capillary condensation theory reveal the mechanism of corrosion in dense porous media.

Science.gov (United States)

Stefanoni, Matteo; Angst, Ueli M; Elsener, Bernhard

2018-05-09

Corrosion in carbonated concrete is an example of corrosion in dense porous media of tremendous socio-economic and scientific relevance. The widespread research endeavors to develop novel, environmentally friendly cements raise questions regarding their ability to protect the embedded steel from corrosion. Here, we propose a fundamentally new approach to explain the scientific mechanism of corrosion kinetics in dense porous media. The main strength of our model lies in its simplicity and in combining the capillary condensation theory with electrochemistry. This reveals that capillary condensation in the pore structure defines the electrochemically active steel surface, whose variability upon changes in exposure relative humidity is accountable for the wide variability in measured corrosion rates. We performed experiments that quantify this effect and find good agreement with the theory. Our findings are essential to devise predictive models for the corrosion performance, needed to guarantee the safety and sustainability of traditional and future cements.

Structural investigation of the ZnSe(001)-c(2×2) surface

DEFF Research Database (Denmark)

Weigand, W.; Müller, A.; Kilian, L.

2003-01-01

Zinc selenide is a model system for II-VI compound semiconductors. The geometric structure of the clean (001)-c(2x2) surface has recently been the subject of intense debate. We report here a surface x-ray-diffraction study on the ZnSe(001)-c(2x2) surface performed under ultrahigh vacuum using...

99Tc and Re incorporated into metal oxide polyoxometalates: oxidation state stability elucidated by electrochemistry and theory.

Science.gov (United States)

McGregor, Donna; Burton-Pye, Benjamin P; Mbomekalle, Israel M; Aparicio, Pablo A; Romo, Susanna; López, Xavier; Poblet, Josep M; Francesconi, Lynn C

2012-08-20

The radioactive element technetium-99 ((99)Tc, half-life = 2.1 × 10(5) years, β(-) of 253 keV), is a major byproduct of (235)U fission in the nuclear fuel cycle. (99)Tc is also found in radioactive waste tanks and in the environment at National Lab sites and fuel reprocessing centers. Separation and storage of the long-lived (99)Tc in an appropriate and stable waste-form is an important issue that needs to be addressed. Considering metal oxide solid-state materials as potential storage matrixes for Tc, we are examining the redox speciation of Tc on the molecular level using polyoxometalates (POMs) as models. In this study we investigate the electrochemistry of Tc complexes of the monovacant Wells-Dawson isomers, α(1)-P(2)W(17)O(61)(10-) (α1) and α(2)-P(2)W(17)O(61)(10-) (α2) to identify features of metal oxide materials that can stabilize the immobile Tc(IV) oxidation state accessed from the synthesized Tc(V)O species and to interrogate other possible oxidation states available to Tc within these materials. The experimental results are consistent with density functional theory (DFT) calculations. Electrochemistry of K(7-n)H(n)[Tc(V)O(α(1)-P(2)W(17)O(61))] (Tc(V)O-α1), K(7-n)H(n)[Tc(V)O(α(2)-P(2)W(17)O(61))] (Tc(V)O-α2) and their rhenium analogues as a function of pH show that the Tc-containing derivatives are always more readily reduced than their Re analogues. Both Tc and Re are reduced more readily in the lacunary α1 site as compared to the α2 site. The DFT calculations elucidate that the highest oxidation state attainable for Re is VII while, under the same electrochemistry conditions, the highest oxidation state for Tc is VI. The M(V)→ M(IV) reduction processes for Tc(V)O-α1 are not pH dependent or only slightly pH dependent suggesting that protonation does not accompany reduction of this species unlike the M(V)O-α2 (M = (99)Tc, Re) and Re(V)O-α1 where M(V/IV) reduction process must occur hand in hand with protonation of the terminal M═O to

Dependence of Optical Properties of SEL-Deposited Silver Gallium Selenide Thin Films on the On-Line Growth Parameter: Annealing Duration

International Nuclear Information System (INIS)

Bhuiyan, M.R.A.; Firoz Hasan, S.M.

2005-01-01

Silver gallium selenide (AGS) composite thin films were formed onto ultrasonically and chemically cleaned glass substrates by successive on-line thermal evaporation of individual elements and post-deposition annealing at 300 0 C for various durations in vacuum. The annealing duration was varied between 5 and 20 minutes. The structural and optical properties of the films were ascertained by x-ray diffraction (XRD) and uv-vis-nir spectrophotometry (photon wavelength ranging between 300 and 2500 nm), respectively. The diffractogram indicated that these films were polycrystalline in nature having tetragonal structure with lattice parameters, a ∼ 6.0034 A and c ∼ 10.9165 A. The optical transmittance and reflectance were utilized to compute the absorption coefficient, refractive index and energy gap of the films. Dependence of the optical and structural properties of the films on various annealing durations has been analyzed. The nature of the optical transitions has been direct allowed with band gap energies ranging between 1.713 and 1.757 eV and refractive indices between 1.596 and 3.351 depending on photon energy as well as annealing duration. (authors)

Direct electrochemistry of hemoglobin immobilized in CuO nanowire bundles.

Science.gov (United States)

Li, Yueming; Zhang, Qian; Li, Jinghong

2010-11-15

It is one of main challenges to find the suitable materials to enhance the direct electron transfer between the electrode and redox protein for direct electrochemistry field. Nano-structured metal oxides have attracted considerable interest because of unique properties, well biocompatibility, and good stability. In this paper, the copper oxide nanowire bundles (CuO NWBs) were prepared via a template route, and the bioelectrochemical performances of hemoglobin (Hb) on the CuO NWBs modified glass carbon electrodes (denoted as Hb-CuO NWBs/GC) were studied. TEM and XRD were used to characterize the morphology and structure of the as synthesized CuO NWBs. Fourier transform-infrared spectroscopy (FT-IR) proved that Hb in the CuO NWBs matrix could retain its native secondary structure. A pair of well-defined and quasi-reversible redox peaks at approximately -0.325 V (vs. Ag/AgCl saturated KCl) were shown in the cyclic voltammogram curve for the Hb-CuO NWBs/GC electrode, which indicated the direct electrochemical behavior. The Hb-CuO NWBs/GC electrode also displayed a good electrocatalytic activity toward the reduction of hydrogen peroxide. These results indicate that the CuO NWBs are good substrates for immobilization of biomolecules and might be promising in the fields of (bio) electrochemical analysis. Copyright © 2010 Elsevier B.V. All rights reserved.

Direct electrochemistry and electrocatalytic behavior of hemoglobin entrapped in Ag@C nanocables/gold nanoparticles nanocomposites film.

Science.gov (United States)

Hu, Xiao-Wei; Mao, Chang-Jie; Song, Ji-Ming; Niu, He-Lin; Zhang, Sheng-Yi; Cui, Rong-Jing

2012-10-01

Direct electrochemistry of hemoglobin (Hb) was successfully fabricated by immobilizing Hb on the nanocomposites containing of Ag@C nanocables and Au nanoparticles (AuNPs) modified glassy carbon electrode (GCE). The immobilized Hb retained its biological activity and shown high catalytic activities to the reduction of H2O2 by circular dicroism (CD) spectrum, fourier transform infrared (FT-IR) spectrum and cyclic voltammetry (CV). Experimental conditions such as scan rate and pH Value were studied and optimized. The results indicated that the resulting biosensor are linear to the concentrations of H2O2 in the ranges of 6.67 x 10(-7)-2.40 x 10(5) M, and the detection limit is 2.02 x 10(-7) M. The electrochemical biosensor has also high stability and good reproducibility.

Two hexagonal series of lanthanoid(III) oxide fluoride selenides.: M{sub 6}O{sub 2}F{sub 8}Se{sub 3} (M = La - Nd) and M{sub 2}OF{sub 2}Se (M = Nd, Sm, Gd - Ho)

Energy Technology Data Exchange (ETDEWEB)

Zimmermann, Dirk D.; Grossholz, Hagen; Wolf, Sarah; Schleid, Thomas [Institut fuer Anorganische Chemie, Universitaet Stuttgart (Germany); Janka, Oliver [Institut fuer Anorganische Chemie, Universitaet Stuttgart (Germany); Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Mueller, Alexander C. [Institut fuer Anorganische Chemie, Universitaet Stuttgart (Germany); Institut fuer Textilchemie und Chemiefasern, Denkendorf (Germany)

2015-09-15

Two hexagonal series of lanthanoid(III) oxide fluoride selenides with similar structure types can be obtained by the reaction of the components MF{sub 3}, M{sub 2}O{sub 3}, M, and Se in sealed niobium tubes at 850 C using CsI as fluxing agent. The compounds with the lighter and larger representatives (M = La - Nd) occur with the formula M{sub 6}O{sub 2}F{sub 8}Se{sub 3}, whereas with the heavier and smaller ones (M = Nd, Sm, Gd - Ho) their composition is M{sub 2}OF{sub 2}Se. For both systems single-crystal determinations were used in all cases. The compounds crystallize in the hexagonal crystal system (space group: P6{sub 3}/m) with lattice parameters of a = 1394-1331 pm and c = 403-372 pm (Z = 2 for M{sub 6}O{sub 2}F{sub 8}Se{sub 3} and Z = 6 for M{sub 2}OF{sub 2}Se). The (M1){sup 3+} cations show different square antiprismatic coordination spheres with or without an extra capping fluoride anion. All (M2){sup 3+} cations exhibit a ninefold coordination environment shaped as tricapped trigonal prism. In both structure types the Se{sup 2-} anions are sixfold coordinated as trigonal prisms of M{sup 3+} cations, being first condensed by edges to generate trimeric units and then via faces to form strands running along [001]. The light anions reside either in threefold triangular or in fourfold tetrahedral cationic coordination. For charge compensation, both structures have to contain a certain amount of oxide besides fluoride anions. Since F{sup -} and O{sup 2-} can not be distinguished by X-ray diffraction, bond-valence calculations were used to address the problem of their adjunction to the available crystallographic sites. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

End-of-Discharge and End-of-Life Prediction in Lithium-Ion Batteries with Electrochemistry-Based Aging Models

Science.gov (United States)

Daigle, Matthew; Kulkarni, Chetan S.

2016-01-01

As batteries become increasingly prevalent in complex systems such as aircraft and electric cars, monitoring and predicting battery state of charge and state of health becomes critical. In order to accurately predict the remaining battery power to support system operations for informed operational decision-making, age-dependent changes in dynamics must be accounted for. Using an electrochemistry-based model, we investigate how key parameters of the battery change as aging occurs, and develop models to describe aging through these key parameters. Using these models, we demonstrate how we can (i) accurately predict end-of-discharge for aged batteries, and (ii) predict the end-of-life of a battery as a function of anticipated usage. The approach is validated through an experimental set of randomized discharge profiles.

Mathematical modeling of synthesis gas fueled electrochemistry and transport including H2/CO co-oxidation and surface diffusion in solid oxide fuel cell

Science.gov (United States)

Bao, Cheng; Jiang, Zeyi; Zhang, Xinxin

2015-10-01

Fuel flexibility is a significant advantage of solid oxide fuel cell (SOFC). A comprehensive macroscopic framework is proposed for synthesis gas (syngas) fueled electrochemistry and transport in SOFC anode with two main novelties, i.e. analytical H2/CO electrochemical co-oxidation, and correction of gas species concentration at triple phase boundary considering competitive absorption and surface diffusion. Staring from analytical approximation of the decoupled charge and mass transfer, we present analytical solutions of two defined variables, i.e. hydrogen current fraction and enhancement factor. Giving explicit answer (rather than case-by-case numerical calculation) on how many percent of the current output contributed by H2 or CO and on how great the water gas shift reaction plays role on, this approach establishes at the first time an adaptive superposition mechanism of H2-fuel and CO-fuel electrochemistry for syngas fuel. Based on the diffusion equivalent circuit model, assuming series-connected resistances of surface diffusion and bulk diffusion, the model predicts well at high fuel utilization by keeping fixed porosity/tortuosity ratio. The model has been validated by experimental polarization behaviors in a wide range of operation on a button cell for H2-H2O-CO-CO2-N2 fuel systems. The framework could be helpful to narrow the gap between macro-scale and meso-scale SOFC modeling.

Simulating Electrochemistry of Hydrothermal Vents on Enceladus and Other Ocean Worlds

Science.gov (United States)

Barge, L. M.; Krause, F. C.; Jones, J. P.; Billings, K.; Sobron, P.

2017-12-01

Gradients generated in hydrothermal systems provide a significant source of free energy for chemosynthetic life, and may play a role in present-day habitability on ocean worlds such as Enceladus that are thought to host hydrothermal activity. Hydrothermal vents are similar in some ways to typical fuel cell devices: redox/pH gradients between seawater and hydrothermal fluid are analogous to the oxidant and fuel reservoirs; conductive natural mineral deposits are analogous to electrodes; and, in hydrothermal chimneys, the porous chimney wall can function as a separator or ion-exchange membrane. Electrochemistry, founded on quantitative study of redox and other chemical disequilibria as well as the chemistry of interfaces, is uniquely suited to studying these systems. We have performed electrochemical studies to better understand the catalytic potential of seafloor minerals and vent chimneys, using samples from a black smoker vent chimney as an initial demonstration. Fuel cell experiments with electrodes made from black smoker chimney material accurately simulated the redox reactions that occur in a geological setting with this particular catalyst. Similar methods with other geo-catalysts (natural or synthetic) could be utilized to test which redox reactions or metabolisms could be driven in other hydrothermal systems, including putative vent systems on other worlds.

Detailed H2 and CO Electrochemistry for a MEA Model Fueled by Syngas

KAUST Repository

Lee, W. Y.

2015-07-17

© The Electrochemical Society. SOFCs can directly oxidize CO in addition to H2, which allows them to be coupled to a gasifier. Many membrane-electrode-assembly (MEA) models neglect CO electrochemistry due to sluggish kinetics and the water-gas-shift reaction, but CO oxidation may be important for high CO-content syngas. The 1D-MEA model presented here incorporates detailed mechanisms for both H2 and CO oxidation, individually fitted to experimental data. These mechanisms are then combined into a single model, which provides a good fit to experimental data for H2/CO mixtures. Furthermore, the model fits H2/CO data best when a single chargetransfer step in the H2 mechanism is assumed to be rate-limiting for all current densities. This differs from the result for H2/H2O mixtures, where H2 adsorption becomes rate-limiting at high current densities. These results indicate that CO oxidation cannot be neglected in MEA models running on CO-rich syngas, and that CO oxidation can alter the H2 oxidation mechanism.

Lack of Delocalization in Compounds with the Grouping C=N---N=C

Czech Academy of Sciences Publication Activity Database

Zuman, P.; Ludvík, Jiří

2000-01-01

Roč. 41, č. 41 (2000), s. 7851-7853 ISSN 0040-4039 R&D Projects: GA ČR GA203/99/0763 Institutional research plan: CEZ:AV0Z4040901; CEZ:A54/98:Z4-040-9-ii Subject RIV: CG - Electrochemistry Impact factor: 2.558, year: 2000

Electrochemistry of Cytochrome P450 BM3 in Sodium Dodecyl Sulfate Films

Science.gov (United States)

Udit, Andrew K.; Hill, Michael G.; Gray, Harry B.

2008-01-01

Direct electrochemistry of the cytochrome P450 BM3 heme domain (BM3) was achieved by confining the protein within sodium dodecyl sulfate (SDS) films on the surface of basal-plane graphite (BPG) electrodes. Cyclic voltammetry revealed the heme FeIII/II redox couple at −330 mV (vs. Ag/AgCl, pH 7.4). Up to 10 V/s, the peak current was linear with scan rate, allowing us to treat the system as surface-confined within this regime. The standard heterogeneous rate constant determined at 10 V/s was estimated to be 10 s−1. Voltammograms obtained for the BM3-SDS-BPG system in the presence of dioxygen exhibited catalytic waves at the onset of FeIII reduction. The altered heme reduction potential of the BM3-SDS-graphite system indicates that SDS is likely bound in the enzyme active-site region. Compared to other P450-surfactant systems, we find redox potentials and electron transfer rates that differ by ~ 100 mV and > 10-fold, respectively, indicating that the nature of the surfactant environment has a significant effect on the observed heme redox properties. PMID:17129070

Electrical and optical characteristics of heterojunction devices composed of silicon nanowires and mercury selenide nanoparticle films on flexible plastics.

Science.gov (United States)

Yeo, Minje; Yun, Junggwon; Kim, Sangsig

2013-09-01

A pn heterojunction device based on p-type silicon (Si) nanowires (NWs) prepared by top-down method and n-type mercury selenide (HgSe) nanoparticles (NPs) synthesized by the colloidal method have been fabricated on a flexible plastic substrate. The synthesized HgSe NPs were analyzed through the effective mass approximation. The characteristics of the heterojunction device were examined and studied with the energy band diagram. The device showed typical diode characteristics with a turn-on voltage of 1.5 V and exhibited a high rectification ratio of 10(3) under relatively low forward bias. Under illumination of 633-nm-wavelength light, the device presented photocurrent efficiency of 117.5 and 20.1 nA/W under forward bias and reverse bias conditions, respectively. Moreover, the photocurrent characteristics of the device have been determined by bending of the plastic substrate upward and downward with strain of 0.8%. Even though the photocurrent efficiency has fluctuations during the bending cycles, the values are roughly maintained for 10(4) bending cycles. This result indicates that the fabricated heterojunction device has the potential to be applied as fundamental elements of flexible nanoelectronics.

Martian Dust Devil Electron Avalanche Process and Associated Electrochemistry

Science.gov (United States)

Jackson, Telana L.; Farrell, William M.; Delory, Gregory T.; Nithianandam, Jeyasingh

2010-01-01

Mars' dynamic atmosphere displays localized dust devils and larger, global dust storms. Based on terrestrial analog studies, electrostatic modeling, and laboratory work these features will contain large electrostatic fields formed via triboelectric processes. In the low-pressure Martian atmosphere, these fields may create an electron avalanche and collisional plasma due to an increase in electron density driven by the internal electrical forces. To test the hypothesis that an electron avalanche is sustained under these conditions, a self-consistent atmospheric process model is created including electron impact ionization sources and electron losses via dust absorption, electron dissociation attachment, and electron/ion recombination. This new model is called the Dust Devil Electron Avalanche Model (DDEAM). This model solves simultaneously nine continuity equations describing the evolution of the primary gaseous chemical species involved in the electrochemistry. DDEAM monitors the evolution of the electrons and primary gas constituents, including electron/water interactions. We especially focus on electron dynamics and follow the electrons as they evolve in the E field driven collisional gas. When sources and losses are self-consistently included in the electron continuity equation, the electron density grows exponentially with increasing electric field, reaching an equilibrium that forms a sustained time-stable collisional plasma. However, the character of this plasma differs depending upon the assumed growth rate saturation process (chemical saturation versus space charge). DDEAM also shows the possibility of the loss of atmospheric methane as a function of electric field due to electron dissociative attachment of the hydrocarbon. The methane destruction rates are presented and can be included in other larger atmospheric models.

Synthesis and electrochemistry properties of Sn-Sb ultrafine particles as anode of lithium-ion batteries

International Nuclear Information System (INIS)

Wang, Zhong; Tian, Wenhuai; Li, Xingguo

2007-01-01

Ultrafine particles of Sn-Sb alloys with different chemical composition have been prepared by hydrogen plasma-metal reaction. Structure, morphology, size and chemical composition of the Sn-Sb ultrafine particles were investigated by transmission electron microscopy, X-ray diffraction, BET gas adsorption, and induction-coupled plasma spectroscopy. It was found that all the particles have spherical shapes, with average particle size in the range of 100-300 nm. The electrochemistry properties as an alternative anode material for lithium-ion batteries have been characterized by constant current cycling and cyclic voltammetry. Electrochemical measurements showed that the alloys with Sn-46.5 at.% Sb have best reversible capacity and capacity retention. It exhibited a high reversible lithium-ion storage capacity of 701 mAh g -1 in the initial cycle, which has remained at 81% (i.e., 566 mAh g -1 ) of its original capacity after 20 cycles

Direct electrochemistry and electrocatalysis of glucose oxidase on three-dimensional interpenetrating, porous graphene modified electrode

International Nuclear Information System (INIS)

Cui, Min; Xu, Bing; Hu, Chuangang; Shao, Hui Bo; Qu, Liangti

2013-01-01

Direct electrochemistry of glucose oxidase (GOD) on three-dimensional (3D) interpenetrating porous graphene electrodes has been reported, which have been fabricated by one-step electrochemical reduction of graphene oxide (GO) from its aqueous suspension. The electrochemically reduced GO (ERGO) modified electrodes exhibited excellent electron transfer properties for GOD and enhanced the enzyme activity and stability by the assistance of chitosan. The immobilized GOD shows a fast electron transfer with the rate constant (k s ) of 6.05 s −1 . It is worth mentioning that in the air-saturated phosphate buffer solution without any mediator, the resultant modified electrodes exhibited low detection limit of 1.7 μM with wide linear range of 0.02–3.2 mM and high sensitivity and high selectivity for measuring glucose. It would also be extended to various enzymes and bioactive molecules to develop the biosensor or other bio-electrochemical devices

Synthesis, structure and electrical properties of a new tin vanadium selenide

International Nuclear Information System (INIS)

Atkins, Ryan; Disch, Sabrina; Jones, Zachary; Haeusler, Ines; Grosse, Corinna; Fischer, Saskia F.; Neumann, Wolfgang; Zschack, Paul; Johnson, David C.

2013-01-01

The turbostratically disordered misfit layer compound (SnSe) 1.15 VSe 2 was synthesized and structurally characterized. Electrical transport measurements suggest this compound undergoes a charge or spin density wave (CDW or SDW) transition, which has not been observed in previous misfit layer compounds. The (SnSe) 1.15 VSe 2 compound, created through the modulated elemental reactants technique, contains highly oriented intergrowths of SnSe bilayers and VSe 2 structured Se–V–Se trilayers with abrupt interfaces between them perpendicular to the c-axis. X-ray diffraction data and transmission electron microscope images show that each constituent has in-plane crystallinity but that there is a random rotational disorder between the constituent layers. Temperature-dependent electrical resistivity data and Hall measurements are consistent with (SnSe) 1.15 VSe 2 being a metal, however an abrupt increase in the resistivity occurs between 30 and 100 K. The carrier concentration decreases by approximately 1 carrier per vanadium atom during this temperature interval. - Graphical abstract: Turbostratically disordered (SnSe) 1.15 VSe 2 . - Highlights: • New compound (SnSe) 1.15 VSe 2 . • Turbostratic disorder. • Charge density wave at 100 K

Application of Carbon-Microsphere-Modified Electrodes for Electrochemistry of Hemoglobin and Electrocatalytic Sensing of Trichloroacetic Acid

Science.gov (United States)

Wang, Wen-Cheng; Yan, Li-Jun; Shi, Fan; Niu, Xue-Liang; Huang, Guo-Lei; Zheng, Cai-Juan; Sun, Wei

2015-01-01

By using the hydrothermal method, carbon microspheres (CMS) were fabricated and used for electrode modification. The characteristics of CMS were investigated using various techniques. The biocompatible sensing platform was built by immobilizing hemoglobin (Hb) on the micrometer-sized CMS-modified electrode with a layer of chitosan membrane. On the cyclic voltammogram, a couple of quasi-reversible cathodic and anodic peaks appeared, showing that direct electrochemistry of Hb with the working electrode was achieved. The catalytic reduction peak currents of the bioelectrode to trichloroacetic acid was established in the linear range of 2.0~70.0 mmol·L−1 accompanied by a detection limit of 0.30 mmol·L−1 (3σ). The modified electrode displayed favorable sensitivity, good reproducibility and stability, which suggests that CMS is promising for fabricating third-generation bioelectrochemical sensors. PMID:26703621

Synthesis, structure and electrical properties of a new tin vanadium selenide

Energy Technology Data Exchange (ETDEWEB)

Atkins, Ryan, E-mail: atkins@uoregon.edu [Department of Chemistry and Materials Science Institute, University of Oregon, Eugene, OR 97403 (United States); Disch, Sabrina, E-mail: disch@ill.fr [Institut Laue-Langevin (ILL), F-38042 Grenoble (France); Jones, Zachary, E-mail: zjones@chem.ucsb.edu [Department of Chemistry and Materials Science Institute, University of Oregon, Eugene, OR 97403 (United States); Haeusler, Ines, E-mail: haeusler@physik.hu-berlin.de [Novel Materials, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany); Grosse, Corinna, E-mail: Corinna.Grosse@physik.hu-berlin.de [Novel Materials, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany); Fischer, Saskia F., E-mail: Saskia.Fischer@physik.hu-berlin.de [Novel Materials, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany); Neumann, Wolfgang, E-mail: wsn@uoregon.edu [Department of Chemistry and Materials Science Institute, University of Oregon, Eugene, OR 97403 (United States); Zschack, Paul, E-mail: zschack@bnl.gov [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Johnson, David C., E-mail: davej@uoregon.edu [Department of Chemistry and Materials Science Institute, University of Oregon, Eugene, OR 97403 (United States)

2013-06-15

The turbostratically disordered misfit layer compound (SnSe){sub 1.15}VSe{sub 2} was synthesized and structurally characterized. Electrical transport measurements suggest this compound undergoes a charge or spin density wave (CDW or SDW) transition, which has not been observed in previous misfit layer compounds. The (SnSe){sub 1.15}VSe{sub 2} compound, created through the modulated elemental reactants technique, contains highly oriented intergrowths of SnSe bilayers and VSe{sub 2} structured Se–V–Se trilayers with abrupt interfaces between them perpendicular to the c-axis. X-ray diffraction data and transmission electron microscope images show that each constituent has in-plane crystallinity but that there is a random rotational disorder between the constituent layers. Temperature-dependent electrical resistivity data and Hall measurements are consistent with (SnSe){sub 1.15}VSe{sub 2} being a metal, however an abrupt increase in the resistivity occurs between 30 and 100 K. The carrier concentration decreases by approximately 1 carrier per vanadium atom during this temperature interval. - Graphical abstract: Turbostratically disordered (SnSe){sub 1.15}VSe{sub 2}. - Highlights: • New compound (SnSe){sub 1.15}VSe{sub 2}. • Turbostratic disorder. • Charge density wave at 100 K.

Formation of CuInSe{sub 2} films from metal sulfide and selenide precursor nanocrystals by gas-phase selenization, an in-situ XRD study

Energy Technology Data Exchange (ETDEWEB)

Capon, B., E-mail: boris.capon@ugent.be [Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, B-9000 Ghent (Belgium); Dierick, R. [Physics and Chemistry of Nanostructures, Ghent University, Krijgslaan 281-S3, B-9000 Ghent (Belgium); Hens, Z. [Physics and Chemistry of Nanostructures, Ghent University, Krijgslaan 281-S3, B-9000 Ghent (Belgium); Center for Nano and Biophotonics, Ghent University, Ghent (Belgium); Detavernier, C. [Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, B-9000 Ghent (Belgium)

2016-08-01

In this work phase pure CuInSe{sub 2} thin flms were obtained by selenization of ternary CuInSe{sub 2} and CuInS{sub 2} nanocrystals and mixtures of binary nanocrystals such as CuS, In{sub 2}S{sub 3}, Cu{sub 2}Se and In{sub 2}Se{sub 3}. The temperature of the selenium source was kept at 400 °C during selenization. Monitoring the process using in-situ x-ray diffraction, the effect of selenization on the phase formation and grain growth in the precursor film was investigated. Whereas CuInSe{sub 2} and CuInS{sub 2} nanocrystals exhibit little grain growth, we found that mixtures of binary nanocrystals can show significant sintering depending on the reaction conditions. For the mixture of CuS and In{sub 2}S{sub 3} nanocrystals, the crystallinity and the morphology of the obtained fims strongly depends on the Cu/In ratio, with a Cu excess strongly promoting grain growth. With mixtures of Cu{sub 2}Se and In{sub 2}Se{sub 3} nanocrystals the selenium partial pressure plays a crucial role. Selenium evaporation from the mixed compounds results in CuInSe{sub 2} films composed of relatively small crystallites. Higher selenium partial pressures however resulted in improved sintering. Incomplete propagation of the selenization reaction through the layer was observed though, only leading to a well sintered CuInSe{sub 2} top layer above a fine grained bottom layer. - Highlights: • Different types of colloidal nanocrystals were used as precursors to obtain CuInSe{sub 2} films by gas-phase selenization. • In-situ XRD was used to study the effect of selenization on the phase formation and grain growth in the precursor films. • For a mixture of binary metal sulfides the crystallinity and the morphology strongly depend on the Cu/In ratio. • Higher selenium partial pressures result in improved sintering for a mixture of binary metal selenides.

Transition from Sign-Reversed to Sign-Preserved Cooper-Pairing Symmetry in Sulfur-Doped Iron Selenide Superconductors.

Science.gov (United States)

Wang, Qisi; Park, J T; Feng, Yu; Shen, Yao; Hao, Yiqing; Pan, Bingying; Lynn, J W; Ivanov, A; Chi, Songxue; Matsuda, M; Cao, Huibo; Birgeneau, R J; Efremov, D V; Zhao, Jun

2016-05-13

An essential step toward elucidating the mechanism of superconductivity is to determine the sign or phase of the superconducting order parameter, as it is closely related to the pairing interaction. In conventional superconductors, the electron-phonon interaction induces attraction between electrons near the Fermi energy and results in a sign-preserved s-wave pairing. For high-temperature superconductors, including cuprates and iron-based superconductors, prevalent weak coupling theories suggest that the electron pairing is mediated by spin fluctuations which lead to repulsive interactions, and therefore that a sign-reversed pairing with an s_{±} or d-wave symmetry is favored. Here, by using magnetic neutron scattering, a phase sensitive probe of the superconducting gap, we report the observation of a transition from the sign-reversed to sign-preserved Cooper-pairing symmetry with insignificant changes in T_{c} in the S-doped iron selenide superconductors K_{x}Fe_{2-y}(Se_{1-z}S_{z})_{2}. We show that a rather sharp magnetic resonant mode well below the superconducting gap (2Δ) in the undoped sample (z=0) is replaced by a broad hump structure above 2Δ under 50% S doping. These results cannot be readily explained by simple spin fluctuation-exchange pairing theories and, therefore, multiple pairing channels are required to describe superconductivity in this system. Our findings may also yield a simple explanation for the sometimes contradictory data on the sign of the superconducting order parameter in iron-based materials.

Electrochemistry in near-critical and supercritical fluids. 3. Studies of Br/sup -/, I/sup -/, and hydroquinone in aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Flarsheim, W.J.; Tsou, Y.M.; Trachtenberg, I.; Johnston, K.P.; Bard, A.J.

1986-07-31

A new type of apparatus has been constructed for carrying out electrochemistry in near-critical and supercritical aqueous solutions. The following systems have been studied at a platinum electrode: H/sub 2/O/O/sub 2/, I/sup -//I/sub 2/, Br/sup -//Br/sub 2/, and hydroquinone/benzoquinone. The compact alumina flow cell can be heated or cooled quickly and can be recharged with fresh electrolyte solution while at high temperature and pressure. A large reduction in the potential required for the electrolysis of water was observed. Diffusivities have been measured for iodide ions and hydroquinone. General agreement with the Stokes-Einstein model was observed in the temperature range 25-375/sup 0/C.

Flower-like Bi2Se3 nanostructures: Synthesis and their application for the direct electrochemistry of hemoglobin and H2O2 detection

International Nuclear Information System (INIS)

Fan Hai; Zhang Shenxiang; Ju Peng; Su Haichao; Ai Shiyun

2012-01-01

Highlights: ► Flower-like Bi 2 Se 3 nanostructures were prepared via a hydrothermal technique. ► Bi 2 Se 3 nanostructures significantly improve the direct electron-transfer of Hb. ► The immobilized Hb shows high catalytic activity to the reduction of H 2 O 2 . - Abstract: In this paper, flower-like Bi 2 Se 3 nanostructures consisting of intercrossed nanosheets networks have been synthesized via a facile hydrothermal technique and applied to the protein electrochemistry for the first time. The prepared Bi 2 Se 3 nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The direct electrochemistry of hemoglobin (Hb) has been achieved by immobilizing Hb on the prepared Bi 2 Se 3 nanostructures and Nafion (Nf) modified glassy carbon electrode. Bi 2 Se 3 nanostructures show significant promotion to the direct electron-transfer of Hb. The immobilized Hb retained its biological activity well and shows high catalytic activity to the reduction of hydrogen peroxide (H 2 O 2 ). Under the optimal experimental conditions, the catalytic currents are linear to the concentrations of H 2 O 2 in the range of 2.0 × 10 −6 to 1.0 × 10 −4 M. The corresponding detection limits are 6.3 × 10 −7 M. The prepared flower-like Bi 2 Se 3 nanostructures provide an alternative matrix for protein immobilization and biosensor preparation.

The Isomers of Gadolinium Scandium Nitride Clusterfullerenes GdxSc3-xN@C80 (x=1, 2) and Their Influence on Cluster Structure

Czech Academy of Sciences Publication Activity Database

Yang, S.; Popov, A.; Kalbáč, Martin; Dunsch, L.

2008-01-01

Roč. 14, č. 7 (2008), s. 2084-2092 ISSN 0947-6539 Institutional research plan: CEZ:AV0Z40400503 Keywords : cluster compounds * fullerenes * lanthanides * structure elucidation Subject RIV: CG - Electrochemistry Impact factor: 5.454, year: 2008

Redox behaviour of uranium with iron compounds

International Nuclear Information System (INIS)

Ithurbide, A.

2009-10-01

An option investigated for the management of long-term nuclear waste is a repository in deep geological formations. It is generally admitted that the release of radionuclides from the spent fuel in the geosphere could occur several thousand years after the beginning of the storage. Therefore, to assess the safety of the long-term disposal, it is important to consider the phenomena that can reduce the migration, and in particular the migration of uranium. The aim of this work is to study if siderite, an iron compound present both in the near - and far -field, can limit this migration as well as the role played by the redox process. Siderite thin layers have been obtained by electrochemistry. The layers are adherent and homogeneous. Their thickness is about 1 μm and they are composed of spherical grains. Analytical characterizations performed show that siderite is free of any impurity and does not exhibit any trace of oxidation. The interactions between siderite and uranium (VI) have been carried out in solutions considered as representative of environmental waters, in terms of pH and carbonate concentration. The retention of uranium on the thin layer is important since, after 24 hours of interaction, it corresponds to retention capacities of several hundreds of uranium micro-moles per gram of siderite. XPS analysis show that, in any studied condition, part of uranium present on the thin layer is reduced into an over stoichiometric uranium dioxide. The process of interaction differs depending on the considered environment, specially on the stability of siderite. (author)

Erratum to Electrochemical single-molecule conductivity of duplex and quadruplex DNA [Current Opinion in Electrochemistry volume 7 (2018) 66-74 of duplicate article](S2451910317300984)(10.1016/j.coelec.2017.09.005)

DEFF Research Database (Denmark)

Zhang, Ling; Zhang, Jingdong; Ulstrup, Jens

2018-01-01

The Publisher regrets that this article is an accidental duplication of an article that has already been published in Current Opinion in Electrochemistry Volume 4 Issue 1 (2017) 166-174, http://dx.doi.org/10.1016/j.coelec.2017.11.009. The duplicate article has therefore been withdrawn. The full...

STM, SECPM, AFM and Electrochemistry on Single Crystalline Surfaces

Directory of Open Access Journals (Sweden)

Ulrich Stimming

2010-08-01

Full Text Available Scanning probe microscopy (SPM techniques have had a great impact on research fields of surface science and nanotechnology during the last decades. They are used to investigate surfaces with scanning ranges between several 100 mm down to atomic resolution. Depending on experimental conditions, and the interaction forces between probe and sample, different SPM techniques allow mapping of different surface properties. In this work, scanning tunneling microscopy (STM in air and under electrochemical conditions (EC-STM, atomic force microscopy (AFM in air and scanning electrochemical potential microscopy (SECPM under electrochemical conditions, were used to study different single crystalline surfaces in electrochemistry. Especially SECPM offers potentially new insights into the solid-liquid interface by providing the possibility to image the potential distribution of the surface, with a resolution that is comparable to STM. In electrocatalysis, nanostructured catalysts supported on different electrode materials often show behavior different from their bulk electrodes. This was experimentally and theoretically shown for several combinations and recently on Pt on Au(111 towards fuel cell relevant reactions. For these investigations single crystals often provide accurate and well defined reference and support systems. We will show heteroepitaxially grown Ru, Ir and Rh single crystalline surface films and bulk Au single crystals with different orientations under electrochemical conditions. Image studies from all three different SPM methods will be presented and compared to electrochemical data obtained by cyclic voltammetry in acidic media. The quality of the single crystalline supports will be verified by the SPM images and the cyclic voltammograms. Furthermore, an outlook will be presented on how such supports can be used in electrocatalytic studies.

ZnO/Cu nanocomposite: a platform for direct electrochemistry of enzymes and biosensing applications.

Science.gov (United States)

Yang, Chi; Xu, Chunxiang; Wang, Xuemei

2012-03-06

Unique structured nanomaterials can facilitate the direct electron transfer between redox proteins and the electrodes. Here, in situ directed growth on an electrode of a ZnO/Cu nanocomposite was prepared by a simple corrosion approach, which enables robust mechanical adhesion and electrical contact between the nanostructured ZnO and the electrodes. This is great help to realize the direct electron transfer between the electrode surface and the redox protein. SEM images demonstrate that the morphology of the ZnO/Cu nanocomposite has a large specific surface area, which is favorable to immobilize the biomolecules and construct biosensors. Using glucose oxidase (GOx) as a model, this ZnO/Cu nanocomposite is employed for immobilization of GOx and the construction of the glucose biosensor. Direct electron transfer of GOx is achieved at ZnO/Cu nanocomposite with a high heterogeneous electron transfer rate constant of 0.67 ± 0.06 s(-1). Such ZnO/Cu nanocomposite provides a good matrix for direct electrochemistry of enzymes and mediator-free enzymatic biosensors.

Mixed-valent and radical states of complexes [(bpy)(2)M(.mu.-abpy)M´(bpy)(2)](n+), M,M´ = Ru or Os, abpy=2,2´-azobispyridine: Electron transfer vs. hole transfer mechanism in azo ligand-bridged complexes

Czech Academy of Sciences Publication Activity Database

Heilmann, M.; Frantz, S.; Kaim, W.; Fiedler, Jan; Duboc, C.

2006-01-01

Roč. 359, č. 3 (2006), s. 821-829 ISSN 0020-1693 R&D Projects: GA MŠk LC510; GA AV ČR IAA400400505; GA ČR GA203/03/0821 Institutional research plan: CEZ:AV0Z40400503 Keywords : mixed valency * osmium compounds * radical ligand s * ruthenium compounds * spectroslectrochemistry Subject RIV: CG - Electrochemistry Impact factor: 1.674, year: 2006

Immobilization, direct electrochemistry and electrocatalysis of hemoglobin on colloidal silver nanoparticles-chitosan film

Energy Technology Data Exchange (ETDEWEB)

Yu Chunmei [College of Chemistry and Chemical Engineering and Materials Science, Suzhou University, Suzhou 215123 (China); Institute of Analytical Chemistry for Life Science, School of Public Health, Nantong University, Nantong 226007 (China); Zhou Xiaohui [Institute of Analytical Chemistry for Life Science, School of Public Health, Nantong University, Nantong 226007 (China); Gu Haiying, E-mail: hygu@ntu.edu.c [Institute of Analytical Chemistry for Life Science, School of Public Health, Nantong University, Nantong 226007 (China)

2010-12-01

This paper reports on the fabrication and characterization of hemoglobin (Hb)-colloidal silver nanoparticles (CSNs)-chitosan film on the glassy carbon electrode and its application on electrochemical biosensing. CSNs could greatly enhance the electron transfer reactivity of Hb as a bridge. In the phosphate buffer solution with pH value of 7.0, Hb showed a pair of well-defined redox peaks with the formal potential (E{sup 0'}) of -0.325 V (vs. SCE). The immobilized Hb in the film maintained its biological activity, showing a surface-controlled process with the heterogeneous electron transfer rate constant (k{sub s}) of 1.83 s{sup -1} and displayed the same features of a peroxidase in the electrocatalytic reduction of oxygen and hydrogen peroxide (H{sub 2}O{sub 2}). The linear range for the determination of H{sub 2}O{sub 2} was from 0.75 {mu}M to 0.216 mM with a detection limit of 0.5 {mu}M (S/N = 3). Such a simple assemble method could offer a promising platform for further study on the direct electrochemistry of other redox proteins and the development of the third-generation electrochemical biosensors.

High thermal conductivity materials for thermal management applications

Science.gov (United States)

Broido, David A.; Reinecke, Thomas L.; Lindsay, Lucas R.

2018-05-29

High thermal conductivity materials and methods of their use for thermal management applications are provided. In some embodiments, a device comprises a heat generating unit (304) and a thermally conductive unit (306, 308, 310) in thermal communication with the heat generating unit (304) for conducting heat generated by the heat generating unit (304) away from the heat generating unit (304), the thermally conductive unit (306, 308, 310) comprising a thermally conductive compound, alloy or composite thereof. The thermally conductive compound may include Boron Arsenide, Boron Antimonide, Germanium Carbide and Beryllium Selenide.

Observed damage during Argon gas cluster depth profiles of compound semiconductors

Energy Technology Data Exchange (ETDEWEB)

Barlow, Anders J., E-mail: anders.barlow@ncl.ac.uk; Portoles, Jose F.; Cumpson, Peter J. [National EPSRC XPS Users' Service (NEXUS), School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom)

2014-08-07

Argon Gas Cluster Ion Beam (GCIB) sources have become very popular in XPS and SIMS in recent years, due to the minimal chemical damage they introduce in the depth-profiling of polymer and other organic materials. These GCIB sources are therefore particularly useful for depth-profiling polymer and organic materials, but also (though more slowly) the surfaces of inorganic materials such as semiconductors, due to the lower roughness expected in cluster ion sputtering compared to that introduced by monatomic ions. We have examined experimentally a set of five compound semiconductors, cadmium telluride (CdTe), gallium arsenide (GaAs), gallium phosphide (GaP), indium arsenide (InAs), and zinc selenide (ZnSe) and a high-κ dielectric material, hafnium oxide (HfO), in their response to argon cluster profiling. An experimentally determined HfO etch rate of 0.025 nm/min (3.95 × 10{sup −2} amu/atom in ion) for 6 keV Ar gas clusters is used in the depth scale conversion for the profiles of the semiconductor materials. The assumption has been that, since the damage introduced into polymer materials is low, even though sputter yields are high, then there is little likelihood of damaging inorganic materials at all with cluster ions. This seems true in most cases; however, in this work, we report for the first time that this damage can in fact be very significant in the case of InAs, causing the formation of metallic indium that is readily visible even to the naked eye.

S K Rangarajan

Indian Academy of Sciences (India)

user

chemistry and many-body theory, photoelectrochemistry, porous electrodes, current ... in applied electrochemistry such as corrosion of metals, and current distribution ... Alagappa Chettiar college of Engineering and Technology in. Karaikudi. .... phenomena (ions, solvent dipoles, organic compounds) at the electrochemical ...

Electrochemical Studies on New Chelating Compounds of the Mono- and Bis(Imidazolyl) Pyridine Type

Czech Academy of Sciences Publication Activity Database

Mikysek, T.; Švancara, I.; Bartoš, M.; Vytřas, K.; Drabina, P.; Sedlák, M.; Klíma, Jiří; Urban, Jiří; Ludvík, Jiří

2007-01-01

Roč. 19, č. 24 (2007), s. 2529-2537 ISSN 1040-0397 R&D Projects: GA MŠk LC510; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40400503 Keywords : voltammetry * polarography * coulometry Subject RIV: CG - Electrochemistry Impact factor: 2.949, year: 2007

An electrochemical device generating metal ion adducts of organic compounds for electrospray mass spectrometry

Czech Academy of Sciences Publication Activity Database

Jaklová Dytrtová, Jana; Jakl, M.; Navrátil, Tomáš; Cvačka, Josef; Pačes, Ondřej

2016-01-01

Roč. 211, Sep 1 (2016), s. 787-793 ISSN 0013-4686 R&D Projects: GA ČR GP13-21409P Institutional support: RVO:61388963 ; RVO:61388955 Keywords : EC-ESI-MS * solid electrode * coupling methods * voltammetry * cyproconazole Subject RIV: CG - Electrochemistry Impact factor: 4.798, year: 2016

Recent Progress in Graphite Intercalation Compounds for Rechargeable Metal (Li, Na, K, Al)-Ion Batteries.

Science.gov (United States)

Xu, Jiantie; Dou, Yuhai; Wei, Zengxi; Ma, Jianmin; Deng, Yonghong; Li, Yutao; Liu, Huakun; Dou, Shixue

2017-10-01

Lithium-ion batteries (LIBs) with higher energy density are very necessary to meet the increasing demand for devices with better performance. With the commercial success of lithiated graphite, other graphite intercalation compounds (GICs) have also been intensively reported, not only for LIBs, but also for other metal (Na, K, Al) ion batteries. In this Progress Report, we briefly review the application of GICs as anodes and cathodes in metal (Li, Na, K, Al) ion batteries. After a brief introduction on the development history of GICs, the electrochemistry of cationic GICs and anionic GICs is summarized. We further briefly summarize the use of cationic GICs and anionic GICs in alkali ion batteries and the use of anionic GICs in aluminium-ion batteries. Finally, we reach some conclusions on the drawbacks, major progress, emerging challenges, and some perspectives on the development of GICs for metal (Li, Na, K, Al) ion batteries. Further development of GICs for metal (Li, Na, K, Al) ion batteries is not only a strong supplement to the commercialized success of lithiated-graphite for LIBs, but also an effective strategy to develop diverse high-energy batteries for stationary energy storage in the future.

The electrochemistry of chromium, chromium-boron and chromium-phosphorus alloys

International Nuclear Information System (INIS)

Moffat, T.P.; Ruf, R.R.; Latanision, R.M.

1987-01-01

It is fairly well established that chromium-metalloid interactions represent the key to understanding the remarkable corrosion behavior of TM-Cr-M glasses; (Fe, Ni, Co,...)-Cr-(P, Si, C, S). The character and kinetics of passive film growth on the glasses are being studied ni order to assess the role of the film former, chromium, and the metalloids in the passivation process. A series of thin film microcrystalline chromium, Cr-B and Cr-P binary alloys have been fabricated by physical vapor deposition techniques. Vacuum melted conventionally processed chromium has also been studied. Examination of these materials in lM H/sub 2/SO/sub 4/ and lM HCl by voltammetry, potentiostatic and impedance techniques yields the following conclusion: 1. Pure chromium with a grain size varying from < 400 A to 0.5 mm exhibits no well defined differences in electrochemical behavior in lM H/sub 2/SO/sub 4/. 2. The tremendous corrosion resistance of Cr-B alloys has been confirmed. 3. The beneficial effects observed for boron alloyed with chromium may be considered surprising in view of the neutral/negative influence of alloying boron with iron, i.e. Fe/sub 80/B/sub 20/. 4. The interaction of the electrochemistry of the metalloid constituent with that of the transition base element determines the corrosion behavior. 5. Preliminary work with Cr-P alloys indicates that certain compositions exhibit promising properties - certain films were found to be intact after two days of immersion in concentrated HCl. Further work is in progress

The importance of electrode material in environmental electrochemistry

International Nuclear Information System (INIS)

Kapalka, Agnieszka; Foti, Gyoergy; Comninellis, Christos

2009-01-01

A model describing the hydroxyl radical (HO·) concentration profile at the boron-doped diamond (BDD) electrode, in the presence and absence of organic compounds, is presented. It is shown that this profile depends strongly on the reaction rate constant between the HO· and the organic compound. Furthermore, it is shown that the presence of organics affects the current-potential (I-V) curves. In fact, the higher the reaction rate between organics and HO·, the higher is the shift of the I-V curves toward lower potential with respect to oxygen evolution. Supposing that water discharge to free hydroxyl radicals on BDD is governed by Nernst equation, this shift of the I-V curves toward lower potentials has been calculated and compared with the experimental data obtained on BDD using two model compounds: methanol and formic acid

Pulsed voltage deposited lead selenide thin film as efficient counter electrode for quantum-dot-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Jin, Bin Bin [Key Laboratory of Macromolecular Science of Shaanxi Province & School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062 (China); Department of Chemical Engineering, Institute of Chemical Industry, Shaanxi Institute of Technology, Xi’an 710300 (China); Wang, Ye Feng [Key Laboratory of Macromolecular Science of Shaanxi Province & School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062 (China); Wang, Xue Qing [Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024 (China); Zeng, Jing Hui, E-mail: jhzeng@ustc.edu [Key Laboratory of Macromolecular Science of Shaanxi Province & School of Materials Science and Engineering, Shaanxi Normal University, Xi’an 710062 (China)

2016-04-30

Highlights: • PbSe thin film is deposited on FTO glass by a pulse voltage electrodeposition method. • The thin film is used as counter electrode (CE) in quantum dot-sensitized solar cell. • Superior electrocatalytic activity and stability in the polysulfide electrolyte is received. • The narrow band gap characteristics and p-type conductivity enhances the cell efficiency. • An efficiency of 4.67% is received for the CdS/CdSe co-sensitized solar cells. - Abstract: Lead selenide (PbSe) thin films were deposited on fluorine doped tin oxide (FTO) glass by a facile one-step pulse voltage electrodeposition method, and used as counter electrode (CE) in CdS/CdSe quantum dot-sensitized solar cells (QDSSCs). A power conversion efficiency of 4.67% is received for the CdS/CdSe co-sensitized solar cells, which is much better than that of 2.39% received using Pt CEs. The enhanced performance is attributed to the extended absorption in the near infrared region, superior electrocatalytic activity and p-type conductivity with a reflection of the incident light at the back electrode in addition. The physical and chemical properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), reflectance spectra, electrochemical impedance spectroscopy (EIS) and Tafel polarization measurements. The present work provides a facile pathway to an efficient CE in the QDSSCs.

In Situ Determination of Bisphenol A in Beverage Using a Molybdenum Selenide/Reduced Graphene Oxide Nanoparticle Composite Modified Glassy Carbon Electrode

Directory of Open Access Journals (Sweden)

Rongguang Shi

2018-05-01

Full Text Available Due to the endocrine disturbing effects of bisphenol A (BPA on organisms, rapid detection has become one of the most important techniques for monitoring its levels in the aqueous solutions associated with plastics and human beings. In this paper, a glassy carbon electrode (GCE modified with molybdenum selenide/reduced graphene oxide (MoSe2/rGO was fabricated for in situ determination of bisphenol A in several beverages. The surface area of the electrode dramatically increases due to the existence of ultra-thin nanosheets in a flower-like structure of MoSe2. Adding phosphotungstic acid in the electrolyte can significantly enhance the repeatability (RSD = 0.4% and reproducibility (RSD = 2.2% of the electrode. Under the optimized condition (pH = 6.5, the linear range of BPA was from 0.1 μM–100 μM and the detection limit was 0.015 μM (S/N = 3. When using the as-prepared electrode for analyzing BPA in beverage samples without any pretreatments, the recoveries ranged from 98–107%, and the concentrations were from below the detection limit to 1.7 μM, indicating its potential prospect for routine analysis of BPA.

In Situ Determination of Bisphenol A in Beverage Using a Molybdenum Selenide/Reduced Graphene Oxide Nanoparticle Composite Modified Glassy Carbon Electrode.

Science.gov (United States)

Shi, Rongguang; Liang, Jing; Zhao, Zongshan; Liu, Yi; Liu, Aifeng

2018-05-22

Due to the endocrine disturbing effects of bisphenol A (BPA) on organisms, rapid detection has become one of the most important techniques for monitoring its levels in the aqueous solutions associated with plastics and human beings. In this paper, a glassy carbon electrode (GCE) modified with molybdenum selenide/reduced graphene oxide (MoSe₂/rGO) was fabricated for in situ determination of bisphenol A in several beverages. The surface area of the electrode dramatically increases due to the existence of ultra-thin nanosheets in a flower-like structure of MoSe₂. Adding phosphotungstic acid in the electrolyte can significantly enhance the repeatability (RSD = 0.4%) and reproducibility (RSD = 2.2%) of the electrode. Under the optimized condition (pH = 6.5), the linear range of BPA was from 0.1 μM⁻100 μM and the detection limit was 0.015 μM (S/ N = 3). When using the as-prepared electrode for analyzing BPA in beverage samples without any pretreatments, the recoveries ranged from 98⁻107%, and the concentrations were from below the detection limit to 1.7 μM, indicating its potential prospect for routine analysis of BPA.

Electrochemistry and determination of epinephrine using a mesoporous Al-incorporated SiO{sub 2} modified electrode

Energy Technology Data Exchange (ETDEWEB)

Zeng, Yanhong; Yang, Jinquan; Wu, Kangbing [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China)

2008-05-30

The potential application of Al-incorporated mesoporous SiO{sub 2} (denoted as Al-MCM-41) in electrochemistry as a novel electrode material was investigated. The peak currents of K{sub 3}[Fe(CN){sub 6}] remarkably increase and the peak potential separation obviously decreases at the mesoporous Al-MCM-41 modified carbon paste electrode (CPE). These phenomena suggest that the mesoporous Al-MCM-41 modified CPE possesses larger electrode area and electron transfer rate constant. Furthermore, the electrochemical behavior of epinephrine (EP) was investigated in different supporting electrolytes such as 0.01 mol L{sup -1} HClO{sub 4} and pH 7.0 phosphate buffer. It is found that the mesoporous Al-MCM-41 modified CPE exhibits catalytic ability to the oxidation of EP due to remarkable peak current enhancement and negative shift of peak potential. The electrochemical oxidation mechanism was also discussed. Finally, a novel electrochemical method was proposed for the determination of EP, which used to determine EP in urine samples. (author)

Electrochemistry and determination of epinephrine using a mesoporous Al-incorporated SiO{sub 2} modified electrode

Energy Technology Data Exchange (ETDEWEB)

Zeng Yanhong; Yang Jinquan [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China); Wu Kangbing [Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074 (China)], E-mail: kbwu@mail.hust.edu.cn

2008-05-30

The potential application of Al-incorporated mesoporous SiO{sub 2} (denoted as Al-MCM-41) in electrochemistry as a novel electrode material was investigated. The peak currents of K{sub 3}[Fe(CN){sub 6}] remarkably increase and the peak potential separation obviously decreases at the mesoporous Al-MCM-41 modified carbon paste electrode (CPE). These phenomena suggest that the mesoporous Al-MCM-41 modified CPE possesses larger electrode area and electron transfer rate constant. Furthermore, the electrochemical behavior of epinephrine (EP) was investigated in different supporting electrolytes such as 0.01 mol L{sup -1} HClO{sub 4} and pH 7.0 phosphate buffer. It is found that the mesoporous Al-MCM-41 modified CPE exhibits catalytic ability to the oxidation of EP due to remarkable peak current enhancement and negative shift of peak potential. The electrochemical oxidation mechanism was also discussed. Finally, a novel electrochemical method was proposed for the determination of EP, which used to determine EP in urine samples.

A multi-site array for combined local electrochemistry and electrophysiology in the non-human primate brain.

Science.gov (United States)

Disney, Anita A; McKinney, Collin; Grissom, Larry; Lu, Xuekun; Reynolds, John H

2015-11-30

Currently, the primary technique employed in circuit-level study of the brain is electrophysiology, recording local field or action potentials (LFPs or APs). However most communication between neurons is chemical and the relationship between electrical activity within neurons and chemical signaling between them is not well understood in vivo, particularly for molecules that signal at least in part by non-synaptic transmission. We describe a multi-contact array and accompanying head stage circuit that together enable concurrent electrophysiological and electrochemical recording. The array is small (electrochemistry) recording. This system is designed for concurrent, dual-mode recording. It is also the only system designed explicitly to meet the challenges of recording in non-human primates. Our system offers the possibility for conducting in vivo studies in a range of species that examine the relationship between the electrical activity of neurons and their chemical environment, with exquisite spatial and temporal precision. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Recent Progress in Graphite Intercalation Compounds for Rechargeable Metal (Li, Na, K, Al)‐Ion Batteries

Science.gov (United States)

Xu, Jiantie; Dou, Yuhai; Wei, Zengxi; Li, Yutao; Liu, Huakun; Dou, Shixue

2017-01-01

Abstract Lithium‐ion batteries (LIBs) with higher energy density are very necessary to meet the increasing demand for devices with better performance. With the commercial success of lithiated graphite, other graphite intercalation compounds (GICs) have also been intensively reported, not only for LIBs, but also for other metal (Na, K, Al) ion batteries. In this Progress Report, we briefly review the application of GICs as anodes and cathodes in metal (Li, Na, K, Al) ion batteries. After a brief introduction on the development history of GICs, the electrochemistry of cationic GICs and anionic GICs is summarized. We further briefly summarize the use of cationic GICs and anionic GICs in alkali ion batteries and the use of anionic GICs in aluminium‐ion batteries. Finally, we reach some conclusions on the drawbacks, major progress, emerging challenges, and some perspectives on the development of GICs for metal (Li, Na, K, Al) ion batteries. Further development of GICs for metal (Li, Na, K, Al) ion batteries is not only a strong supplement to the commercialized success of lithiated‐graphite for LIBs, but also an effective strategy to develop diverse high‐energy batteries for stationary energy storage in the future. PMID:29051856

Electrochemistry-based approaches to low cost, high sensitivity, automated, multiplexed protein immunoassays for cancer diagnostics.

Science.gov (United States)

Dixit, Chandra K; Kadimisetty, Karteek; Otieno, Brunah A; Tang, Chi; Malla, Spundana; Krause, Colleen E; Rusling, James F

2016-01-21

Early detection and reliable diagnostics are keys to effectively design cancer therapies with better prognoses. The simultaneous detection of panels of biomarker proteins holds great promise as a general tool for reliable cancer diagnostics. A major challenge in designing such a panel is to decide upon a coherent group of biomarkers which have higher specificity for a given type of cancer. The second big challenge is to develop test devices to measure these biomarkers quantitatively with high sensitivity and specificity, such that there are no interferences from the complex serum or tissue matrices. Lastly, integrating all these tests into a technology that does not require exclusive training to operate, and can be used at point-of-care (POC) is another potential bottleneck in futuristic cancer diagnostics. In this article, we review electrochemistry-based tools and technologies developed and/or used in our laboratories to construct low-cost microfluidic protein arrays for the highly sensitive detection of a panel of cancer-specific biomarkers with high specificity which at the same time has the potential to be translated into POC applications.

Direct electrochemistry of dopamine on gold-Agaricus bisporus laccase enzyme electrode: characterization and quantitative detection.

Science.gov (United States)

Shervedani, Reza Karimi; Amini, Akbar

2012-04-01

Direct electrochemistry of a new laccase enzyme immobilized on gold and its application as a biosensor for dopamine (DA) are investigated by voltammetry and electrochemical impedance spectroscopy. The sensor demonstrated a redox adsorption behavior with E(0') = + 180 mV vs. Ag/AgCl for immobilized Agaricus bisporus laccase (LacAB) enzyme. The MPA platform was assembled on Au with and without utilization of ultrasounds. Excellent results were obtained by using the enzyme electrode fabricated based on MPA assembled with sonication. The LacAB immobilized in this condition showed a large electrocatalytic activity for oxidation of DA. Accordingly, a third-generation (mediator free) biosensor was constructed for DA. The DA concentration could be measured in the linear range of 0.5 to 13.0 and 47.0 to 430.0 μmol L(-1) with correlation coefficients of 0.999 and 0.989, respectively, and a detection limit of 29.0 nmol L(-1). The biosensor was successfully tested for determination of DA in human blood plasma and pharmaceutical samples. Copyright © 2011 Elsevier B.V. All rights reserved.

C-type Nd2Se3

Directory of Open Access Journals (Sweden)

2009-03-01

Full Text Available The title compound, neodymium sesquiselenide, is isotypic with the other known rare-earth metal(III selenides M2Se3 (M = La–Pr and Sm–Lu with the cubic C-type structure. It adopts a cation-defective Th3P4-type arrangement with close to 8/9 of the unique neodymium-cation site occupied, leading to the composition Nd2.667Se4 (Z = 4 or Nd2Se3 (Z = 5.333, respectively. The Nd3+ cations are thus surrounded by eight selenide anions, forming trigonal [NdSe8]13− dodecahedra, whereas the Se2− anions exhibit a sixfold coordination, but due to the under-occupation of neodymium, each one is statistically surrounded by only 5.333 cations. The crystal studied was a merohedral twin with a 0.31 (6:0.69 (6 domain ratio.

Liquid / liquid biphasic electrochemistry in ultra-turrax dispersed acetonitrile / aqueous electrolyte systems

International Nuclear Information System (INIS)

Watkins, John D.; Amemiya, Fumihiro; Atobe, Mahito; Bulman-Page, Philip C.; Marken, Frank

2010-01-01

Unstable acetonitrile | aqueous emulsions generated in situ with ultra-turrax agitation are investigated for applications in dual-phase electrochemistry. Three modes of operation for liquid / liquid aqueous-organic electrochemical processes are demonstrated with no intentionally added electrolyte in the organic phase based on (i) the formation of a water-soluble product in the aqueous phase in the presence of the organic phase, (ii) the formation of a product and ion transfer at the liquid / liquid-electrode triple phase boundary, and (iii) the formation of a water-insoluble product in the aqueous phase which then transfers into the organic phase. A three-electrode electrolysis cell with ultra-turrax agitator is employed and characterised for acetonitrile / aqueous 2 M NaCl two phase electrolyte. Three redox systems are employed in order to quantify the electrolysis cell performance. The one-electron reduction of Ru(NH 3 ) 6 3+ in the aqueous phase is employed to determine the rate of mass transport towards the electrode surface and the effect of the presence of the acetonitrile phase. The one-electron oxidation of n-butylferrocene in acetonitrile is employed to study triple phase boundary processes. Finally, the one-electron reduction of cobalticenium cations in the aqueous phase is employed to demonstrate the product transfer from the electrode surface into the organic phase. Potential applications in biphasic electrosynthesis are discussed.

Colloid electrochemistry of conducting polymer: towards potential-induced in-situ drug release

International Nuclear Information System (INIS)

Sankoh, Supannee; Vagin, Mikhail Yu.; Sekretaryova, Alina N.; Thavarungkul, Panote; Kanatharana, Proespichaya; Mak, Wing Cheung

2017-01-01

Highlights: • Pulsed electrode potential induced an in-situ drug release from dispersion of conducting polymer microcapsules. • Fast detection of the released drug within the colloid microenvironment. • Improved the efficiency of localized drug release at the electrode interface. - Abstract: Over the past decades, controlled drug delivery system remains as one of the most important area in medicine for various diseases. We have developed a new electrochemically controlled drug release system by combining colloid electrochemistry and electro-responsive microcapsules. The pulsed electrode potential modulation led to the appearance of two processes available for the time-resolved registration in colloid microenvironment: change of the electronic charge of microparticles (from 0.5 ms to 0.1 s) followed by the drug release associated with ionic equilibration (1–10 s). The dynamic electrochemical measurements allow the distinction of drug release associated with ionic relaxation and the change of electronic charge of conducting polymer colloid microparticles. The amount of released drug (methylene blue) could be controlled by modulating the applied potential. Our study demonstrated a surface-potential driven controlled drug release of dispersion of conducting polymer carrier at the electrode interfaces, while the bulk colloids dispersion away from the electrode remains as a reservoir to improve the efficiency of localized drug release. The developed new methodology creates a model platform for the investigations of surface potential-induced in-situ electrochemical drug release mechanism.

Direct electrochemistry and electrocatalysis of myoglobin immobilized on zirconia/multi-walled carbon nanotube nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Liang, Ruping; Deng, Minqiang; Cui, Sanguan; Chen, Hong [Department of Chemistry and Institute for Advanced Study, Nanchang University, Nanchang 330031 (China); Qiu, Jianding, E-mail: jdqiu@ncu.edu.cn [Department of Chemistry and Institute for Advanced Study, Nanchang University, Nanchang 330031 (China)

2010-12-15

Zirconia/multi-walled carbon nanotube (ZrO{sub 2}/MWCNT) nanocomposite was prepared by hydrothermal treatment of MWCNTs in ZrOCl{sub 2}.8H{sub 2}O aqueous solution. The morphology and structure of the synthesized ZrO{sub 2}/MWCNT nanocomposite were characterized by transmission electron microscopy and X-ray diffraction analysis. It was found that ZrO{sub 2} nanoparticles homogeneously distributed on the sidewall of MWCNTs. Myoglobin (Mb), as a model protein to investigate the nanocomposite, was immobilized on ZrO{sub 2}/MWCNT nanocomposite. Ultraviolet-visible spectroscopy and electrochemical measurements showed that the nanocomposite could retain the bioactivity of the immobilized Mb to a large extent. The Mb immobilized in the composite showed excellent direct electrochemistry and electrocatalytic activity to the reduction of hydrogen peroxide (H{sub 2}O{sub 2}). The linear response range of the biosensor to H{sub 2}O{sub 2} concentration was from 1.0 to 116.0 {mu}M with the limit of detection of 0.53 {mu}M (S/N = 3). The ZrO{sub 2}/MWCNT nanocomposite provided a good biocompatible matrix for protein immobilization and biosensors preparation.

Direct electrochemistry of glucose oxidase assembled on graphene and application to glucose detection

International Nuclear Information System (INIS)

Wu Ping; Shao Qian; Hu Yaojuan; Jin Juan; Yin Yajing; Zhang Hui; Cai Chenxin

2010-01-01

The direct electrochemistry of glucose oxidase (GOx) integrated with graphene was investigated. The voltammetric results indicated that GOx assembled on graphene retained its native structure and bioactivity, exhibited a surface-confined process, and underwent effective direct electron transfer (DET) reaction with an apparent rate constant (k s ) of 2.68 s -1 . This work also developed a novel approach for glucose detection based on the electrocatalytic reduction of oxygen at the GOx-graphene/GC electrode. The assembled GOx could electrocatalyze the reduction of dissolved oxygen. Upon the addition of glucose, the reduction current decreased, which could be used for glucose detection with a high sensitivity (ca. 110 ± 3 μA mM -1 cm -2 ), a wide linear range (0.1-10 mM), and a low detection limit (10 ± 2 μM). The developed approach can efficiently exclude the interference of commonly coexisting electroactive species due to the use of a low detection potential (-470 mV, versus SCE). Therefore, this study has not only successfully achieved DET reaction of GOx assembled on graphene, but also established a novel approach for glucose detection and provided a general route for fabricating graphene-based biosensing platform via assembling enzymes/proteins on graphene surface.

Simulation of the oxidative metabolism of diclofenac by electrochemistry/(liquid chromatography/)mass spectrometry.

Science.gov (United States)

Faber, Helene; Melles, Daniel; Brauckmann, Christine; Wehe, Christoph Alexander; Wentker, Kristina; Karst, Uwe

2012-04-01

Diclofenac is a frequently prescribed drug for rheumatic diseases and muscle pain. In rare cases, it may be associated with a severe hepatotoxicity. In literature, it is discussed whether this toxicity is related to the oxidative phase I metabolism, resulting in electrophilic quinone imines, which can subsequently react with nucleophiles present in the liver in form of glutathione or proteins. In this work, electrochemistry coupled to mass spectrometry is used as a tool for the simulation of the oxidative pathway of diclofenac. Using this purely instrumental approach, diclofenac was oxidized in a thin layer cell equipped with a boron doped diamond working electrode. Sum formulae of generated oxidation products were calculated based on accurate mass measurements with deviations below 2 ppm. Quinone imines from diclofenac were detected using this approach. It could be shown for the first time that these quinone imines do not react with glutathione exclusively but also with larger molecules such as the model protein β-lactoglobulin A. A tryptic digest of the generated drug-protein adduct confirms that the protein is modified at the only free thiol-containing peptide. This simple and purely instrumental set-up offers the possibility of generating reactive metabolites of diclofenac and to assess their reactivity rapidly and easily.

Integration of electrochemistry with ultra-performance liquid chromatography/mass spectrometry.

Science.gov (United States)

Cai, Yi; Zheng, Qiuling; Liu, Yong; Helmy, Roy; Loo, Joseph A; Chen, Hao

2015-01-01

This study presents the development of ultra-performance liquid chromatography (UPLC) mass spectrometry (MS) combined with electrochemistry (EC) for the first time and its application for the structural analysis of proteins/peptides that contain disulfide bonds. In our approach, a protein/peptide mixture sample undergoes a fast UPLC separation and subsequent electrochemical reduction in an electrochemical flow cell followed by online MS and tandem mass spectrometry (MS/MS) analyses. The electrochemical cell is coupled to the mass spectrometer using our recently developed desorption electrospray ionization (DESI) interface. Using this UPLC/EC/DESI-MS method, peptides that contain disulfide bonds can be differentiated from those without disulfide bonds, as the former are electroactive and reducible. MS/MS analysis of the disulfide-reduced peptide ions provides increased information on the sequence and disulfide-linkage pattern. In a reactive DESI- MS detection experiment in which a supercharging reagent was used to dope the DESI spray solvent, increased charging was obtained for the UPLC-separated proteins. Strikingly, upon online electrolytic reduction, supercharged proteins (e.g., α-lactalbumin) showed even higher charging, which will be useful in top- down protein structure MS analysis as increased charges are known to promote protein ion dissociation. Also, the separation speed and sensitivity are enhanced by approximately 1(~)2 orders of magnitude by using UPLC for the liquid chromatography (LC)/EC/MS platform, in comparison to the previously used high- performance liquid chromatography (HPLC). This UPLC/EC/DESI-MS method combines the power of fast UPLC separation, fast electrochemical conversion, and online MS structural analysis for a potentially valuable tool for proteomics research and bioanalysis.

Electrochemistry of potentially bioreductive alkylating quinones : Part 1. Electrochemical properties of relatively simple quinones, as model compounds of mitomycin- and aziridinylquinone-type antitumour agents

NARCIS (Netherlands)

Driebergen, R.J.; den Hartigh, J.; Holthuis, J.J.M.; Hulshoff, A.; van Oort, W.J.; Postma kelder, S.J.; Verboom, Willem; Reinhoudt, David; Bos, M.; van der Linden, W.E.

1990-01-01

The influence of methyl-, hydroxy and amino substituents on the electrochemical behaviour of simple 1,4-naphtho-and 1,4-benzoquinones, model compounds of many quinoid antitumour agents, in aqueous media was studied. Significant changes in electrochemical behaviour were observed, potentially the

Ruthenium Stilbenyl and Diruthenium Distyrylethene Complexes: Aspects of Electron Delocalization and Electrocatalyzed Isomerization of the Z-Isomer

Czech Academy of Sciences Publication Activity Database

Linseis, M.; Záliš, Stanislav; Zabel, M.; Winter, R. F.

2012-01-01

Roč. 134, č. 40 (2012), s. 16671-16692 ISSN 0002-7863 R&D Projects: GA MŠk LD11086 Institutional support: RVO:61388955 Keywords : CIS-TRANS-ISOMERIZATION * MIXED-VALENCE COMPOUNDS * VIBRATIONAL TIME -SCALE Subject RIV: CG - Electrochemistry Impact factor: 10.677, year: 2012

Liquid-Mercury Free Silver Solid Amalgam Electrode - Tool for Electroanalysis of Organic Compounds

Czech Academy of Sciences Publication Activity Database

Šelešovská-Fadrná, R.; Navrátil, Tomáš; Vlček, Milan

2007-01-01

Roč. 52, č. 6 (2007), s. 911-929 ISSN 0009-2223 R&D Projects: GA ČR GA203/07/1195; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40500505 Keywords : ascorbic acid * solid silver amalgam electrodes * cysteine * voltammetry Subject RIV: CG - Electrochemistry Impact factor: 0.529, year: 2007

A detailed approach to model transport, heterogeneous chemistry, and electrochemistry in solid-oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Janardhanan, V.

2007-07-01

This dissertation layes out detailed descriptions for heterogeneous chemistry, electrochemistry, and porous media transport models to simulate solid oxide fuel cells (SOFCs). An elementary like heterogeneous reaction mechanism for the steam reforming of CH4 developed in our research group is used throughout this work. Based on assumption of hydrogen oxidation as the only electrochemical reaction and single step electron transfer reaction as rate limiting, a modified Butler-Volmer equation is used to model the electrochemistry. The pertinence of various porous media transport models such as Modified Fick Model (MFM), Dusty Gas Model (DGM), Mean Transport Pore Model, Modified Maxwell Stefan Model, and Generalized Maxwell Stefan Model under reaction conditions are studied. In general MFM and DGM predictions are in good agreement with experimental data. Physically realistic electrochemical model parameters are very important for fuel cell modeling. Button cell simulations are carried out to deduce the electrochemical model parameters, and those parameters are further used in the modeling of planar cells. Button cell simulations are carried out using the commercial CFD code FLUENT coupled with DETCHEM. For all temperature ranges the model works well in predicting the experimental observations in the high current density region. However, the model predicts much higher open circuit potentials than that observed in the experiments, mainly due to the absence of coking model in the elementary heterogeneous mechanism leading to nonequilibrium compositions. Furthermore, the study presented here employs Nernst equation for the calculation of reversible potential which is strictly valid only for electrochemical equilibrium. It is assumed that the electrochemical charge transfer reaction involving H2 is fast enough to be in equilibrium. However, the comparison of model prediction with thermodynamic equilibrium reveals that this assumption is violated under very low current

Morphologic, magnetic, and Moessbauer spectral properties of Fe75Co25 nanoparticles prepared by ultrasound-assisted electrochemistry

International Nuclear Information System (INIS)

Mancier, Valerie; Delplancke, J.-L.; Delwiche, Jacques; Hubin-Franskin, M.-J.; Piquer, Cristina; Rebbouh, Leila; Grandjean, Fernande

2004-01-01

Nanopowders of Fe 75 Co 25 alloys have been prepared by ultrasound-assisted electrochemistry. Their composition, crystallographic structure, morphology, have been studied by X-ray diffraction, transmission electron microscopy, X-ray fluorescence, and high-energy electron diffraction. The nanopowders are found to present a composition well determined by the electrolyte bath composition, they show a bcc structure. The iron and cobalt atoms exhibit a very homogeneous distribution in the particles. The magnetic properties of the nanopowders have been measured between 5 and 295 K with a vibrating sample magnetometer and their Moessbauer spectra have been obtained at 295 K. The saturation magnetization is characteristic of FeCo alloys. The magnetic behavior and transmission electron microscopy observations of the particles indicate strongly interacting particles with a radius of ca. 2-4 nm, particles which may form agglomerates of larger size. The measured average hyperfine field is situated at the maximum of the Slater-Pauling curve for the FeCo alloys

Interconnection of Key Microbial Functional Genes for Enhanced Benzo[a]pyrene Biodegradation in Sediments by Microbial Electrochemistry.

Science.gov (United States)

Yan, Zaisheng; He, Yuhong; Cai, Haiyuan; Van Nostrand, Joy D; He, Zhili; Zhou, Jizhong; Krumholz, Lee R; Jiang, He-Long

2017-08-01

Sediment microbial fuel cells (SMFCs) can stimulate the degradation of polycyclic aromatic hydrocarbons in sediments, but the mechanism of this process is poorly understood at the microbial functional gene level. Here, the use of SMFC resulted in 92% benzo[a]pyrene (BaP) removal over 970 days relative to 54% in the controls. Sediment functions, microbial community structure, and network interactions were dramatically altered by the SMFC employment. Functional gene analysis showed that c-type cytochrome genes for electron transfer, aromatic degradation genes, and extracellular ligninolytic enzymes involved in lignin degradation were significantly enriched in bulk sediments during SMFC operation. Correspondingly, chemical analysis of the system showed that these genetic changes resulted in increases in the levels of easily oxidizable organic carbon and humic acids which may have resulted in increased BaP bioavailability and increased degradation rates. Tracking microbial functional genes and corresponding organic matter responses should aid mechanistic understanding of BaP enhanced biodegradation by microbial electrochemistry and development of sustainable bioremediation strategies.

DC-electrochemiluminescence (ECL with a coreactant)—principle and applications in organic chemistry

Czech Academy of Sciences Publication Activity Database

Ludvík, Jiří

2011-01-01

Roč. 15, č. 10 (2011), s. 2065-2081 ISSN 1432-8488 R&D Projects: GA AV ČR IAA400400813 Institutional research plan: CEZ:AV0Z40400503 Keywords : organic compounds * reaction mechanisms * radical intermediates Subject RIV: CG - Electrochemistry Impact factor: 2.131, year: 2011

Electrical properties of silver selenide thin films prepared by reactive ...

Indian Academy of Sciences (India)

Unknown

2001-07-29

Jul 29, 2001 ... tion of a given vapour at a given rate takes place only if the temperature of ... temperature for evaporation of compound and subsequent decomposition ... Electrical conductivity and Hall effect measurements were carried out ...

Electrochemistry at a Metal Nanoparticle on a Tunneling Film: A Steady-State Model of Current Densities at a Tunneling Ultramicroelectrode.

Science.gov (United States)

Hill, Caleb M; Kim, Jiyeon; Bard, Allen J

2015-09-09

Here, a new methodology is proposed for treating electrochemical current densities in metal-insulator-metal nanoparticle (M-I-MNP) systems. The described model provides broad, practical insights about MNP-mediated electron transfer to redox species in solution, where electron transfer from the underlying electrode to a MNP via tunneling and heterogeneous electron transfer from the MNP to redox species in solution are treated as sequential steps. Tunneling is treated through an adaptation of the Simmons model of tunneling in metal-insulator-metal structures, and explicit equations are provided for tunneling currents, which demonstrate the effect of various experimental parameters, such as insulator thickness and MNP size. Overall, a general approach is demonstrated for determining experimental conditions where tunneling will have a measurable impact on the electrochemistry of M-I-MNP systems.

Electrometallurgy of copper refinery anode slimes

Science.gov (United States)

Scott, J. D.

1990-08-01

High-selenium copper refinery anode slimes form two separate and dynamically evolving series of compounds with increasing electrolysis time. In one, silver is progressively added to non-stoichiometric copper selenides, both those originally present in the anode and those formed subsequently in the slime layer, and in the other, silver-poor copper selenides undergo a dis-continuous crystallographic sequence of anodic-oxidative transformations. The silver-to-selenium molar ratio in the as-cast anode and the current density of electrorefining can be used to construct predominance diagrams for both series and, thus, to predict the final bulk “mineralogy” of the slimes. Although totally incorrect in detail, these bulk data are sufficiently accurate to provide explanations for several processing problems which have been experienced by Kidd Creek Division, Falconbridge Ltd., in its commercial tankhouse. They form the basis for a computer model which predicts final cathode quality from chemical analyses of smelter feed.

Studies on Cd1Se0.6Te0.4 Thin Films by Spectroscopic and Diffractometer Characterization

Directory of Open Access Journals (Sweden)

Cliff Orori Mosiori

2017-09-01

Full Text Available Cadmium selenide tellurium is a compound containing cadmium, tellurium and selenium elements forming a combined solid. Hall measurements suggest that it is an n-type semiconductor. Related optical studies indicate that is transparent to infra-red radiation. Structural studies clearly show that it has a wurtzite, sphalerite crystalline forms. Cadmium is a toxic heavy metal, and selenium is only toxic in large amounts or doses. By this toxicity, cadmium selenide is a known to be carcinogen to humans; however, this does not stop investigating it for optoelectronic applications. Current research has narrowed down to investigating cadmium selenide when in the form of nanoparticles. Cadmium selenide finds applications has found applications in opto-electronic devices like laser diodes, biomedical imaging, nano-sensing, high-efficiency solar cells and thin-film transistors. By chemical bath deposition, Cd1Se0.6Te0.4 thin films were grown onto glass. Tellurium was gradually introduced as an impurity and its crystalline structure and optical properties were investigated by XRD and UV-VIS spectroscopy. The main Cd1Se0.6Te0.4/glass characteristics were correlated with the conditions of growing and post-growth treatment and it was found out that films were homogeneous films with controllable thickness onto the glass substrate and suitable for n-type “sandwich” heterostructures applications. Comparison of the intensities of equivalent reflexions provided a test for the internal consistency of the measurements. Equivalent reflexions in two specimens differed on average by 1.4 % and 0.6% from the mean measured intensity, attesting to the high internal consistency of measurements from extended-face crystals. By comparison from data obtained from all samples showed their average deviation from the mean to be 0.9 %.

Solid Amalgam Composite Electrode as a New Sensor for the Determination of Biologically Active Compounds

Czech Academy of Sciences Publication Activity Database

Josypčuk, Bohdan; Navrátil, Tomáš; Lukina, A.; Pecková, K.; Barek, J.

2007-01-01

Roč. 52, č. 6 (2007), s. 897-910 ISSN 0009-2223 R&D Projects: GA ČR GA203/07/1195; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40400503 Keywords : solid composite electrode * solid amalgam electrodes * solid amalgam composite electrode * voltammetry Subject RIV: CG - Electrochemistry Impact factor: 0.529, year: 2007

Iodine-catalyzed sp³ C-H bond activation by selenium dioxide: synthesis of diindolylmethanes and di(3-indolyl)selanides.

Science.gov (United States)

Naidu, P Seetham; Majumder, Swarup; Bhuyan, Pulak J

2015-11-01

An efficient reaction protocol was developed for the synthesis of several diindolylmethane derivatives via the [Formula: see text] C-H bond activation of aryl methyl ketones by [Formula: see text] and indoles in the presence of catalytic amounts of [Formula: see text] at 80 [Formula: see text] using dioxane as solvent. Unexpectedly, an interesting class of di(3-indolyl)selenide compounds was isolated when the reaction was carried out at room temperature.

Actinide, lanthanide and fission product speciation and electrochemistry in high and low temperature ionic melts

Energy Technology Data Exchange (ETDEWEB)

Bhatt, Anand I.; Kinoshita, Hajime; Koster, Anne L.; May, Iain; Sharrad, Clint A.; Volkovich, Vladimir A.; Fox, O. Danny; Jones, Chris J.; Lewin, Bob G.; Charnock, John M.; Hennig, Christoph

2004-07-01

There is currently a great deal of research interest in the development of molten salt technology, both classical high temperature melts and low temperature ionic liquids, for the electrochemical separation of the actinides from spent nuclear fuel. We are interested in gaining a better understanding of actinide and key fission product speciation and electrochemical properties in a range of melts. Our studies in high temperature alkali metal melts (including LiCl and LiCl-KCl and CsCl-NaCl eutectics) have focussed on in-situ species of U, Th, Tc and Ru using X-ray absorption spectroscopy (XAS, both EXAFS and XANES) and electronic absorption spectroscopy (EAS). We report unusual actinide speciation in high temperature melts and an evaluation of the likelihood of Ru or Tc volatilization during plant operation. Our studies in lower temperature melts (ionic liquids) have focussed on salts containing tertiary alkyl group 15 cations and the bis(tri-fluor-methyl)sulfonyl)imide anion, melts which we have shown to have exceptionally wide electrochemical windows. We report Ln, Th, U and Np speciation (XAS, EAS and vibrational spectroscopy) and electrochemistry in these melts and relate the solution studies to crystallographic characterised benchmark species. (authors)

Actinide, lanthanide and fission product speciation and electrochemistry in high and low temperature ionic melts

International Nuclear Information System (INIS)

Bhatt, Anand I.; Kinoshita, Hajime; Koster, Anne L.; May, Iain; Sharrad, Clint A.; Volkovich, Vladimir A.; Fox, O. Danny; Jones, Chris J.; Lewin, Bob G.; Charnock, John M.; Hennig, Christoph

2004-01-01

There is currently a great deal of research interest in the development of molten salt technology, both classical high temperature melts and low temperature ionic liquids, for the electrochemical separation of the actinides from spent nuclear fuel. We are interested in gaining a better understanding of actinide and key fission product speciation and electrochemical properties in a range of melts. Our studies in high temperature alkali metal melts (including LiCl and LiCl-KCl and CsCl-NaCl eutectics) have focussed on in-situ species of U, Th, Tc and Ru using X-ray absorption spectroscopy (XAS, both EXAFS and XANES) and electronic absorption spectroscopy (EAS). We report unusual actinide speciation in high temperature melts and an evaluation of the likelihood of Ru or Tc volatilization during plant operation. Our studies in lower temperature melts (ionic liquids) have focussed on salts containing tertiary alkyl group 15 cations and the bis(tri-fluor-methyl)sulfonyl)imide anion, melts which we have shown to have exceptionally wide electrochemical windows. We report Ln, Th, U and Np speciation (XAS, EAS and vibrational spectroscopy) and electrochemistry in these melts and relate the solution studies to crystallographic characterised benchmark species. (authors)

Observation of nanometer-sized electro-active defects in insulating layers by fluorescence microscopy and electrochemistry.

Science.gov (United States)

Renault, Christophe; Marchuk, Kyle; Ahn, Hyun S; Titus, Eric J; Kim, Jiyeon; Willets, Katherine A; Bard, Allen J

2015-06-02

We report a method to study electro-active defects in passivated electrodes. This method couples fluorescence microscopy and electrochemistry to localize and size electro-active defects. The method was validated by comparison with a scanning probe technique, scanning electrochemical microscopy. We used our method for studying electro-active defects in thin TiO2 layers electrodeposited on 25 μm diameter Pt ultramicroelectrodes (UMEs). The permeability of the TiO2 layer was estimated by measuring the oxidation of ferrocenemethanol at the UME. Blocking of current ranging from 91.4 to 99.8% was achieved. Electro-active defects with an average radius ranging between 9 and 90 nm were observed in these TiO2 blocking layers. The distribution of electro-active defects over the TiO2 layer is highly inhomogeneous and the number of electro-active defect increases for lower degree of current blocking. The interest of the proposed technique is the possibility to quickly (less than 15 min) image samples as large as several hundreds of μm(2) while being able to detect electro-active defects of only a few tens of nm in radius.

Direct Electrochemistry of Hemoglobin at a Graphene Gold Nanoparticle Composite Film for Nitric Oxide Biosensing

Directory of Open Access Journals (Sweden)

Guang-Chao Zhao

2013-06-01

Full Text Available A simple two-step method was employed for preparing nano-sized gold nanoparticles-graphene composite to construct a GNPs-GR-SDS modified electrode. Hemoglobin (Hb was successfully immobilized on the surface of a basal plane graphite (BPG electrode through a simple dropping technique. Direct electrochemistry and electrocatalysis of the hemoglobin-modified electrode was investigated. The as-prepared composites showed an obvious promotion of the direct electro-transfer between hemoglobin and the electrode. A couple of well-defined and quasi-reversible Hb CV peaks can be observed in a phosphate buffer solution (pH 7.0. The separation of anodic and cathodic peak potentials is 81 mV, indicating a fast electron transfer reaction. The experimental results also clarified that the immobilized Hb retained its biological activity for the catalysis toward NO. The biosensor showed high sensitivity and fast response upon the addition of NO, under the conditions of pH 7.0, potential ‒0.82 V. The time to reach the stable-state current was less than 3 s, and the linear response range of NO was 0.72–7.92 μM, with a correlation coefficient of 0.9991.

Forecasting of chalcogenide spinels of the general formula AB2X4 using the method of training of an electronic computer

International Nuclear Information System (INIS)

Kiseleva, N.N.; Savitskij, E.M.

1979-01-01

Experimental evidence on the existence of AB 2 X 4 compounds in A-B-X systems (A and B are any elements of the periodic system, in particular, rare earth elements, X is S or Se) and the data on the properties of elements and simple sulphides (selenides) were used for an attempt to find the probability of formation of AB 2 X 4 compounds as a function of the component properties. The experimental evidence was analyzed by a computer employing algorithms of concept formation training. The results were used to predict new AB 2 X 4 compounds. The computer training method proved an efficient means of revealing the connection between probability of spinel type compounds existence with the component properties. Certain compounds of general formula AB 2 X 4 were predicted and the probability that they possess spinel structure was evaluated

Chemistry Division annual progress report for period ending July 31, 1981

International Nuclear Information System (INIS)

1982-01-01

Research is reported on: chemistry of coal liquefaction, aqueous chemistry at high temperatures, geosciences, high-temperature chemistry and thermodynamics of structural materials, chemistry of TRU elements and compounds, separations chemistry, electrochemistry, nuclear waste chemistry, chemical physics, theoretical chemistry, inorganic chemistry of hydrogen cycles, molten salt systems, and enhanced oil recovery. Separate abstracts were prepared for the sections dealing with coal liquefaction, TRU elements and compounds, separations, nuclear wastes, and enhanced oil recovery

Chemistry Division annual progress report for period ending July 31, 1981

Energy Technology Data Exchange (ETDEWEB)

1982-01-01

Research is reported on: chemistry of coal liquefaction, aqueous chemistry at high temperatures, geosciences, high-temperature chemistry and thermodynamics of structural materials, chemistry of TRU elements and compounds, separations chemistry, electrochemistry, nuclear waste chemistry, chemical physics, theoretical chemistry, inorganic chemistry of hydrogen cycles, molten salt systems, and enhanced oil recovery. Separate abstracts were prepared for the sections dealing with coal liquefaction, TRU elements and compounds, separations, nuclear wastes, and enhanced oil recovery. (DLC)

Metal interactions with boron clusters

International Nuclear Information System (INIS)

Grimes, R.N.

1982-01-01

This book presents information on the following topics: the structural and bonding features of metallaboranes and metallacarboranes; transition-metal derivatives of nido-boranes and some related species; interactions of metal groups with the octahydrotriborate (1-) anion, B 3 H 8 ; metallaboron cage compounds of the main group metals; closo-carborane-metal complexes containing metal-carbon and metal-boron omega-bonds; electrochemistry of metallaboron cage compounds; and boron clusters with transition metal-hydrogen bonds

Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions

KAUST Repository

Samu, Gergely F.; Scheidt, Rebecca A; Kamat, Prashant V.; Janá ky, Csaba

2017-01-01

The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and to assemble their hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr3 and hybrid organic-inorganic MaPbI3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. We believe that the presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that easier comparisons can be made.

Corrosion of structural materials and electrochemistry in high temperature water of nuclear power systems

International Nuclear Information System (INIS)

Uchida, Shunsuke

2008-01-01

The latest experiences with corrosion in the cooling systems of nuclear power plants are reviewed. High temperature cooling water causes corrosion of structural materials, which often leads to adverse effects in the plants, e.g., increased shutdown radiation, generation of defects in materials of major components and fuel claddings, and increased volume of radwaste sources. Corrosion behavior is greatly affected by water quality and differs according to the water quality values and the materials themselves. In order to establish reliable operation, each plant requires its own unique optimal water chemistry control based on careful consideration of its system, materials and operational history. Electrochemistry is one of the key issues that determine corrosion-related problems, but it is not the only issue. Most corrosion-related phenomena, e.g., flow accelerated corrosion (FAC), intergranular stress corrosion cracking (IGSCC), primary water stress corrosion cracking (PWSCC) and thinning of fuel cladding materials, can be understood based on an electrochemical index, e.g., the electrochemical corrosion potential (ECP), conductivities and pH. The most important electrochemical index, the ECP, can be measured at elevated temperature and applied to in situ sensors of corrosion conditions to detect anomalous conditions of structural materials at their very early stages. (orig.)

Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions.

Science.gov (United States)

Samu, Gergely F; Scheidt, Rebecca A; Kamat, Prashant V; Janáky, Csaba

2018-02-13

The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and for assembling them into hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr 3 and hybrid organic-inorganic MAPbI 3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. The presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that comparisons can more easily be made.

Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions

KAUST Repository

Samu, Gergely F.

2017-12-06

The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and to assemble their hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr3 and hybrid organic-inorganic MaPbI3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. We believe that the presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that easier comparisons can be made.

Tetramer model of leukoemeraldine-emeraldine electrochemistry in the presence of trihalogenoacetic acids. DFT approach.

Science.gov (United States)

Barbosa, Nuno Almeida; Grzeszczuk, Maria; Wieczorek, Robert

2015-01-15

First results of the application of the DFT computational approach to the reversible electrochemistry of polyaniline are presented. A tetrameric chain was used as the simplest model of the polyaniline polymer species. The system under theoretical investigation involved six tetramer species, two electrons, and two protons, taking part in 14 elementary reactions. Moreover, the tetramer species were interacting with two trihalogenoacetic acid molecules. Trifluoroacetic, trichloroacetic, and tribromoacetic acids were found to impact the redox transformation of polyaniline as shown by cyclic voltammetry. The theoretical approach was considered as a powerful tool for investigating the main factors of importance for the experimental behavior. The DFT method provided molecular structures, interaction energies, and equilibrium energies of all of the tetramer-acid complexes. Differences between the energies of the isolated tetramer species and their complexes with acids are discussed in terms of the elementary reactions, that is, ionization potentials and electron affinities, equilibrium constants, electrode potentials, and reorganization energies. The DFT results indicate a high impact of the acid on the reorganization energy of a particular elementary electron-transfer reaction. The ECEC oxidation path was predicted by the calculations. The model of the reacting system must be extended to octamer species and/or dimeric oligomer species to better approximate the real polymer situation.

Forensic electrochemistry: indirect electrochemical sensing of the components of the new psychoactive substance "Synthacaine".

Science.gov (United States)

Cumba, Loanda R; Kolliopoulos, Athanasios V; Smith, Jamie P; Thompson, Paul D; Evans, Peter R; Sutcliffe, Oliver B; do Carmo, Devaney R; Banks, Craig E

2015-08-21

"Synthacaine" is a New Psychoactive Substance which is, due to its inherent psychoactive properties, reported to imitate the effects of cocaine and is therefore consequently branded as "legal cocaine". The only analytical approach reported to date for the sensing of "Synthacaine" is mass spectrometry. In this paper, we explore and evaluate a range of potential analytical techniques for its quantification and potential use in the field screening "Synthacaine" using Raman spectroscopy, presumptive (colour) testing, High Performance Liquid Chromatography (HPLC) and electrochemistry. HPLC analysis of street samples reveals that "Synthacaine" comprises a mixture of methiopropamine (MPA) and 2-aminoindane (2-AI). Raman spectroscopy and presumptive (colour) tests, the Marquis, Mandelin, Simon's and Robadope test, are evaluated towards a potential in-the-field screening approach but are found to not be able to discriminate between the two when they are both present in the same sample, as is the case in the real street samples. We report for the first time a novel indirect electrochemical protocol for the sensing of MPA and 2-AI which is independently validated in street samples with HPLC. This novel electrochemical approach based upon one-shot disposable cost effective screen-printed graphite macroelectrodes holds potential for in-the-field screening for "Synthacaine".

Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions

Science.gov (United States)

2017-01-01

The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and for assembling them into hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr3 and hybrid organic–inorganic MAPbI3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. The presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that comparisons can more easily be made. PMID:29503507

Direct electrochemistry and electrocatalysis of glucose oxidase immobilized on reduced graphene oxide and silver nanoparticles nanocomposite modified electrode.

Science.gov (United States)

Palanisamy, Selvakumar; Karuppiah, Chelladurai; Chen, Shen-Ming

2014-02-01

The direct electrochemistry of glucose oxidase (GOx) was successfully realized on electrochemically reduced graphene oxide and silver nanoparticles (RGO/Ag) nanocomposite modified electrode. The fabricated nanocomposite was characterized by field emission scanning electron microscope and energy dispersive spectroscopy. The GOx immobilized nanocomposite modified electrode showed a pair of well-defined redox peaks with a formal potential (E°) of -0.422 V, indicating that the bioactivity of GOx was retained. The heterogeneous electron transfer rate constant (Ks) of GOx at the nanocomposite was calculated to be 5.27 s(-1), revealing a fast direct electron transfer of GOx. The GOx immobilized RGO/Ag nanocomposite electrode exhibited a good electrocatalytic activity toward glucose over a linear concentration range from 0.5 to 12.5 mM with a detection limit of 0.16 mM. Besides, the fabricated biosensor showed an acceptable sensitivity and selectivity for glucose. Copyright © 2013 Elsevier B.V. All rights reserved.

In situ STM imaging and direct electrochemistry of Pyrococcus furiosus ferredoxin assembled on thiolate-modified Au(111) surfaces

DEFF Research Database (Denmark)

Zhang, Jingdong; Christensen, Hans Erik Mølager; Ooi, Bee Lean

2004-01-01

We have addressed here electron transfer (ET) of Pyrococcus furiosus ferredoxin (PfFd, 7.5 kDa) in both homogeneous solution using edge plane graphite (EPG) electrodes and in the adsorbed state by electrochemistry on surface-modified single-crystal Au(111) electrodes, This has been supported...... by surface microscopic structures of PfFd monolayers, as revealed by scanning tunneling microscopy under potential control (in situ STM). Direct ET between PfFd in phosphate buffer solution, pH 7.9, and EPG electrodes is observed in the presence of promoters. Neomycin gives rise to a pair of redox peaks...... with a formal potential of ca -430 mV (vs SCE), corresponding to [3Fe-4S](1+/0). The presence of an additional promoter, which can be propionic acid, alanine, or cysteine, induces a second pair of redox peaks at similar to-900 mV (vs SCE) arising from [3Fe-4S](0/1-). A robust neomycin-PfFd complex was detected...