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Sample records for electrochemical microscopy secm

  1. Local deposition of anisotropic nanoparticles using scanning electrochemical microscopy (SECM).

    Science.gov (United States)

    Fedorov, Roman G; Mandler, Daniel

    2013-02-28

    We demonstrate localized electrodeposition of anisotropic metal nanoobjects, namely Au nanorods (GNR), on indium tin oxide (ITO) using scanning electrochemical microscopy (SECM). A gold microelectrode was the source of the gold ions whereby double pulse chronoamperometry was employed to generate initially Au seeds which were further grown under controlled conditions. The distance between the microelectrode and the ITO surface as well as the different experimental parameters (electrodeposition regime, solution composition and temperature) were optimized to produce faceted gold seeds with the required characteristics (size and distribution). Colloidal chemical synthesis was successfully exploited for better understanding the role of the surfactant and different additives in breaking the crystallographic symmetry and anisotropic growth of GNR. Experiments performed in a conventional three-electrode cell revealed the most appropriate electrochemical conditions allowing high yield synthesis of nanorods with well-defined shape as well as nanocubes and bipyramids.

  2. Redox competition mode of scanning electrochemical microscopy (RC-SECM) for visualisation of local catalytic activity.

    Science.gov (United States)

    Eckhard, Kathrin; Chen, Xingxing; Turcu, Florin; Schuhmann, Wolfgang

    2006-12-07

    In order to locally analyse catalytic activity on modified surfaces a transient redox competition mode of scanning electrochemical microscopy (SECM) has been developed. In a bi-potentiostatic experiment the SECM tip competes with the sample for the very same analyte. This leads to a current decrease at the SECM tip, if it is positioned in close proximity to an active catalyst site on the surface. Specifically, local catalytic activity of a Pt-catalyst modified sample with respect to the catalytic reduction of molecular oxygen was investigated. At higher local catalytic activity the local 02 partial pressure within the gap between accurately positioned SECM tip and sample is depleted, leading to a noticeable tip current decrease over active sites. A flexible software module has been implemented into the SECM to adapt the competition conditions by proper definition of tip and sample potentials. A potential pulse profile enables the localised electrochemically induced generation of molecular oxygen prior to the competition detection. The current decay curves are recorded over the entire duration of the applied reduction pulse. Hence, a time resolved processing of the acquired current values provides movies of the local oxygen concentration against x,y-position. The SECM redox competition mode was verified with a macroscopic Pt-disk electrode as a test sample to demonstrate the feasibility of the approach. Moreover, highly dispersed electro-deposited spots of gold and platinum on glassy carbon were visualised using the redox competition mode of SECM. Catalyst spots of different nature as well as activity inhomogeneities within one spot caused by local variations in Pt-loading were visualised successfully.

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

    Science.gov (United States)

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

    2015-01-01

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

  4. Fabrication, characterization, and functionalization of dual carbon electrodes as probes for scanning electrochemical microscopy (SECM).

    Science.gov (United States)

    McKelvey, Kim; Nadappuram, Binoy Paulose; Actis, Paolo; Takahashi, Yasufumi; Korchev, Yuri E; Matsue, Tomokazu; Robinson, Colin; Unwin, Patrick R

    2013-08-06

    Dual carbon electrodes (DCEs) are quickly, easily, and cheaply fabricated by depositing pyrolytic carbon into a quartz theta nanopipet. The size of DCEs can be controlled by adjusting the pulling parameters used to make the nanopipet. When operated in generation/collection (G/C) mode, the small separation between the electrodes leads to reasonable collection efficiencies of ca. 30%. A three-dimensional finite element method (FEM) simulation is developed to predict the current response of these electrodes as a means of estimating the probe geometry. Voltammetric measurements at individual electrodes combined with generation/collection measurements provide a reasonable guide to the electrode size. DCEs are employed in a scanning electrochemical microscopy (SECM) configuration, and their use for both approach curves and imaging is considered. G/C approach curve measurements are shown to be particularly sensitive to the nature of the substrate, with insulating surfaces leading to enhanced collection efficiencies, whereas conducting surfaces lead to a decrease of collection efficiency. As a proof-of-concept, DCEs are further used to locally generate an artificial electron acceptor and to follow the flux of this species and its reduced form during photosynthesis at isolated thylakoid membranes. In addition, 2-dimensional images of a single thylakoid membrane are reported and analyzed to demonstrate the high sensitivity of G/C measurements to localized surface processes. It is finally shown that individual nanometer-size electrodes can be functionalized through the selective deposition of platinum on one of the two electrodes in a DCE while leaving the other one unmodified. This provides an indication of the future versatility of this type of probe for nanoscale measurements and imaging.

  5. Reactivity at the film/solution interface of ex situ prepared bismuth film electrodes: A scanning electrochemical microscopy (SECM) and atomic force microscopy (AFM) investigation

    International Nuclear Information System (INIS)

    Hocevar, Samo B.; Daniele, Salvatore; Bragato, Carlo; Ogorevc, Bozidar

    2007-01-01

    Bismuth film electrodes (BiFEs) prepared ex situ with and without complexing bromide ions in the modification solution were investigated using scanning electrochemical microscopy (SECM) and atomic force microscopy (AFM). A feedback mode of the SECM was employed to examine the conductivity and reactivity of a series of thin bismuth films deposited onto disk glassy carbon substrate electrodes (GCEs) of 3 mm in diameter. A platinum micro-electrode (φ = 25 μm) was used as the SECM tip, and current against tip/substrate distance was recorded in solutions containing either Ru(NH 3 ) 6 3+ or Fe(CN) 6 4- species as redox mediators. With both redox mediators positive feedback approach curves were recorded, which indicated that the bismuth film deposition protocol associated with the addition of bromide ions in the modification solution did not compromise the conductivity of the bismuth film in comparison with that prepared without bromide. However, at the former Bi film a slight kinetic hindering was observed in recycling Ru(NH 3 ) 6 3+ , suggesting a different surface potential. On the other hand, the approach curves recorded by using Fe(CN) 6 4- showed that both types of the aforementioned bismuth films exhibited local reactivity with the oxidised form of the redox mediator, and that bismuth film obtained with bromide ions exhibited slightly lower reactivity. The use of SECM in the scanning operation mode allowed us to ascertain that the bismuth deposits were uniformly distributed across the whole surface of the glassy carbon substrate electrode. Comparative AFM measurements corroborated the above findings and additionally revealed a denser growth of smaller bismuth crystals over the surface of the substrate electrode in the presence of bromide ions, while the crystals were bigger but sparser in the absence of bromide ions in the modification solution

  6. Respiration activity of Escherichia coli entrapped in a cone-shaped microwell and cylindrical micropore monitored by scanning electrochemical microscopy (SECM).

    Science.gov (United States)

    Kaya, Takatoshi; Numai, Daisuke; Nagamine, Kuniaki; Aoyagi, Shigeo; Shiku, Hitoshi; Matsue, Tomokazu

    2004-06-01

    The metabolic activity of E. coli cells embedded in collagen gel microstructures in a cone-shaped well and in a cylindrical micropore was investigated using scanning electrochemical microscopy (SECM), based on the oxygen consumption rate and the conversion rate from ferrocyanide to ferricyanide. The analysis of the concentration profiles for oxygen and ferrocyanide afforded the oxygen consumption rate and the ferrocyanide production rate. A comparison indicated that the ferrocyanide production rates were larger than the oxygen consumption rate, and also that the rates observed in the cylindrical micropore were larger than those observed in the cone-shaped well. The ferrocyanide production rate of a single E. coli cell was calculated to be (5.4 +/- 2.6) x 10(-19) mol s(-1), using a cylindrical micropore system.

  7. Simultaneous noncontact topography and electrochemical imaging by SECM/SICM featuring ion current feedback regulation.

    Science.gov (United States)

    Takahashi, Yasufumi; Shevchuk, Andrew I; Novak, Pavel; Murakami, Yumi; Shiku, Hitoshi; Korchev, Yuri E; Matsue, Tomokazu

    2010-07-28

    We described a hybrid system of scanning electrochemical microscopy (SECM) and scanning ion conductance microscopy (SICM) with ion current feedback nanopositioning control for simultaneous imaging of noncontact topography and spatial distribution of electrochemical species. A nanopipette/nanoring electrode probe provided submicrometer resolution of the electrochemical measurement on surfaces with complex topology. The SECM/SICM probe had an aperture radius of 220 nm. The inner and outer radii of the SECM Au nanoring electrode were 330 and 550 nm, respectively. Characterization of the probe was performed with scanning electron microscopy (SEM), cyclic voltammetry (CV), and approach curve measurements. SECM/SICM was applied to simultaneous imaging of topography and electrochemical responses of enzymes (horse radish peroxidase (HRP) and glucose oxidase (GOD)) and single live cells (A6 cells, superior cervical ganglion (SCG) cells, and cardiac myocytes). The measurements revealed the distribution of activity of the enzyme spots on uneven surfaces with submicrometer resolution. SECM/SICM acquired high resolution topographic images of cells together with the map of electrochemical signals. This combined technique was also applied to the evaluation of the permeation property of electroactive species through cellular membranes.

  8. SECM photography

    OpenAIRE

    Zhang, M; Su, B; Cortés-Salazar, F; Hojeij, M; Girault, H H

    2008-01-01

    A novel strategy for imaging commercial black-and-white negative photo films by scanning electrochemical microscopy (SECM) is demonstrated. The imaging is based on using IrCl3 6 as the redox mediator to dissolve silver grains. The SECM probe is biased at a sufficient constant anodic potential (0.8 V vs. Ag QRE) to oxidize IrCl3 6 under diffusion control. SECM images of a patterned band array (2.8 mm 3 mm) and of an ‘‘EPFL” logo (8.6 mm 7 mm) have been recorded with a high resolution fro...

  9. Electrochemical gating in scanning electrochemical microscopy

    NARCIS (Netherlands)

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

    2008-01-01

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

  10. Spectrally encoded confocal microscopy (SECM) for rapid assessment of breast excision specimens (Conference Presentation)

    Science.gov (United States)

    Brachtel, Elena F.; Johnson, Nicole B.; Huck, Amelia E.; Rice-Stitt, Travis L.; Vangel, Mark G.; Smith, Barbara L.; Tearney, Guillermo J.; Kang, DongKyun

    2016-03-01

    Unacceptably large percentage (20-40%) of breast cancer lumpectomy patients are required to undergo multiple surgeries when positive margins are found upon post-operative histologic assessment. If the margin status can be determined during surgery, surgeon can resect additional tissues to achieve tumor-free margin, which will reduce the need for additional surgeries. Spectrally encoded confocal microscopy (SECM) is a high-speed reflectance confocal microscopy technology that has a potential to image the entire surgical margin within a short procedural time. Previously, SECM was shown to rapidly image a large area (10 mm by 10 mm) of human esophageal tissue within a short procedural time (15 seconds). When used in lumpectomy, SECM will be able to image the entire margin surface of ~30 cm2 in around 7.5 minutes. SECM images will then be used to determine margin status intra-operatively. In this paper, we present results from a study of testing accuracy of SECM for diagnosing malignant breast tissues. We have imaged freshly-excised breast specimens (N=46) with SECM. SECM images clearly visualized histomorphologic features associated with normal/benign and malignant breast tissues in a similar manner to histologic images. Diagnostic accuracy was tested by comparing SECM diagnoses made by three junior pathologists with corresponding histologic diagnoses made by a senior pathologist. SECM sensitivity and specificity were high, 0.91 and 0.93, respectively. Intra-observer agreement and inter-observer agreement were also high, 0.87 and 0.84, respectively. Results from this study showed that SECM has a potential to accurately determine margin status during breast cancer lumpectomy.

  11. Use of Local Electrochemical Methods (SECM, EC-STM) and AFM to Differentiate Microstructural Effects (EBSD) on Very Pure Copper

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Lombardia, Esther; Graeve, Iris De; Terryn, Herman [Vrije Universiteit Brussel, Brussels (Belgium); Lapeire, Linsey; Verbeken, Kim; Kestens, Leo [Ghent University, Zwijnaarde (Ghent) (Belgium); Maurice, Vincent; Klein, Lorena; Marcus, Philippe [Institut de Recherche de Chimie Paris, Paris (France); Gonzalez-Garcia, Yaiza; Mol, Arjan [Delft University of Technology, Delft (Netherlands)

    2017-02-15

    When aiming for an increased and more sustainable use of metals a thorough knowledge of the corrosion phenomenon as function of the local metal microstructure is of crucial importance. In this work, we summarize the information presented in our previous publications and present an overview of the different local (electrochemical) techniques that have been proven to be effective in studying the relation between different microstructural variables and their different electrochemical behavior. Atomic force microscopy (AFM), scanning electrochemical microscopy (SECM), and electrochemical scanning tunneling microscopy (EC-STM) were used in combination with electron backscatter diffraction (EBSD). Consequently, correlations could be identified between the grain orientation and grain boundary characteristics, on the one hand, and the electrochemical behavior on the other hand. The grain orientation itself has an influence on the corrosion, and the orientation of the neighboring grains also seems to play a decisive role in the dissolution rate. With respect to intergranular corrosion, only coherent twin boundaries seem to be resistant.

  12. Mapping the antioxidant activity of apple peels with soft probe scanning electrochemical microscopy

    OpenAIRE

    Lin, Tzu-En; Lesch, Andreas; Li, Chi-Lin; Girault, Hubert

    2017-01-01

    We present a non-invasive electrochemical strategy for mapping the antioxidant (AO) activity of apple peels, which counterbalances oxidative stress caused by various external effectors. Soft carbon microelectrodes were used for soft probe scanning electrochemical microscopy (SECM) enabling the gentle and scratch-free in contact mode scanning of the rough and delicate apple peels in an electrolyte solution. The SECM feedback mode was applied using ferrocene methanol (FcMeOH) as redox mediator ...

  13. Scanning Electrochemical Microscopy as a Tool for the Characterization of Dental Erosion

    Directory of Open Access Journals (Sweden)

    Pollyana S. Castro

    2011-01-01

    Full Text Available When the tooth is exposed to acidic environments, an irreversible loss of dental hard tissue occurs in a process called dental erosion. In this work, the scanning electrochemical microscopy (SECM was used to probe the consumption of protons at the vicinity of a tooth surface with a platinum microelectrode fixed at −0.5 (V versus Ag/AgCl/KCl(sat. SECM approach curves were recorded to assess the extent of diffusion in the solution close to the tooth substrate. SECM images clearly demonstrated that the acid erosion process is very fast at solution pH values in the range between 3 and 4.

  14. Probing individual redox PEGylated gold nanoparticles by electrochemical--atomic force microscopy.

    Science.gov (United States)

    Huang, Kai; Anne, Agnès; Bahri, Mohamed Ali; Demaille, Christophe

    2013-05-28

    Electrochemical-atomic force microscopy (AFM-SECM) was used to simultaneously probe the physical and electrochemical properties of individual ~20 nm sized gold nanoparticles functionalized by redox-labeled PEG chains. The redox PEGylated nanoparticles were assembled onto a gold electrode surface, forming a random nanoarray, and interrogated in situ by a combined AFM-SECM nanoelectrode probe. We show that, in this so-called mediator-tethered (Mt) mode, AFM-SECM affords the nanometer resolution required for resolving the position of individual nanoparticles and measuring their size, while simultaneously electrochemically directly contacting the redox-PEG chains they bear. The dual measurement of the size and current response of single nanoparticles uniquely allows the statistical distribution in grafting density of PEG on the nanoparticles to be determined and correlated to the nanoparticle diameter. Moreover, because of its high spatial resolution, Mt/AFM-SECM allows "visualizing" simultaneously but independently the PEG corona and the gold core of individual nanoparticles. Beyond demonstrating the achievement of single-nanoparticle resolution using an electrochemical microscopy technique, the results reported here also pave the way toward using Mt/AFM-SECM for imaging nano-objects bearing any kind of suitably redox-labeled (bio)macromolecules.

  15. Design and fabrication of nanoelectrodes for applications with scanning electrochemical microscopy

    Science.gov (United States)

    Thakar, Rahul

    Scanning electrochemical microscope (SECM) was introduced two decades ago and has since emerged as a powerful research tool to investigate localized electrochemical reactions at the surface of material and biological samples. The ability to obtain chemical information at a surface differentiates SECM from competing scanning probe microscopy (SPM) techniques. Although, chemical specificity is a unique advantage offered by SECM, inherent limitations due to a slow feedback response, and challenges associated with production of smaller electrodes have remained major drawbacks. Initially in this research, SECM was utilized as a characterization and investigative tool. Later, advances in SECM imaging were achieved with design and production of multifunctional nanoelectrodes. At first, platinum based nanoelectrodes were fabricated for use as electrochemical probes to investigate local electron transfer at chemically-modified surfaces. Further, micron and sub-micron platinum electrodes with chemically modified shrouds were prepared and characterized with voltammetric measurements. Studies reveal experimental evidence for the presence of edge-effects that are typically associated with submicron electrodes. Interestingly, we observed selectivity of these electrodes based on hydrophobic/ hydrophilic character. Through vapor deposition of parylene over microstructured material, single-pore membranes and porous membrane arrays were produced. Pore size characterization within porous membranes was performed with templated growth of micro/nanostructures. Characterization of transport properties of ions and redox-active molecules through hydrophobic parylene membranes was investigated with ion conductance microscopy and SECM, individually. Parylene is an insulative material that is chemically resistant, deposits conformally over high-aspect ratio objects and also converts into conductive carbon at high-temperature pyrolysis. Motivated by these results we identified a unique

  16. Ultramicroelectrode voltammetry and scanning electrochemical microscopy in room-temperature ionic liquid electrolytes.

    Science.gov (United States)

    Walsh, Darren A; Lovelock, Kevin R J; Licence, Peter

    2010-11-01

    The high viscosity and unusual properties of room temperature ionic liquids (RTILs) present a number of challenges when performing steady-state voltammetry and scanning electrochemical microscopy in RTILs. These include difficulties in recording steady-state currents at ultramicroelectrode surfaces due to low diffusion coefficients of redox species and problems associated with unequal diffusion coefficients of oxidised and reduced species in RTILs. In this tutorial review, we highlight the recent progress in the use of RTILs as electrolytes for ultramicroelectrode voltammetry and SECM. We describe the basic principles of ultramicroelectrode voltammetry and SECM and, using examples from the recent literature, we discuss the conditions that must be met to perform steady-state voltammetry and SECM measurements in RTILs. Finally, we briefly discuss the electrochemical insights that can be obtained from such measurements.

  17. Electrochemical force microscopy

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-01-10

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

  18. Switching Transient Generation in Surface Interrogation Scanning Electrochemical Microscopy and Time-of-Flight Techniques.

    Science.gov (United States)

    Ahn, Hyun S; Bard, Allen J

    2015-12-15

    In surface interrogation scanning electrochemical microscopy (SI-SECM), fine and accurate control of the delay time between substrate generation and tip interrogation (tdelay) is crucial because tdelay defines the decay time of the reactive intermediate. In previous applications of the SI-SECM, the resolution in the control of tdelay has been limited to several hundreds of milliseconds due to the slow switching of the bipotentiostat. In this work, we have improved the time resolution of tdelay control up to ca. 1 μs, enhancing the SI-SECM to be competitive in the time domain with the decay of many reactive intermediates. The rapid switching SI-SECM has been implemented in a substrate generation-tip collection time-of-flight (SG-TC TOF) experiment of a solution redox mediator, and the results obtained from the experiment exhibited good agreement with that obtained from digital simulation. The reaction rate constant of surface Co(IV) on oxygen-evolving catalyst film, which was inaccessible thus far due to the lack of tdelay control, has been measured by the rapid switching SI-SECM.

  19. Nano-Electrochemistry and Nano-Electrografting with an Original Combined AFM-SECM

    Directory of Open Access Journals (Sweden)

    Ammar Ben Brahim

    2013-05-01

    Full Text Available This study demonstrates the advantages of the combination between atomic force microscopy and scanning electrochemical microscopy. The combined technique can perform nano-electrochemical measurements onto agarose surface and nano-electrografting of non-conducting polymers onto conducting surfaces. This work was achieved by manufacturing an original Atomic Force Microscopy-Scanning ElectroChemical Microscopy (AFM-SECM electrode. The capabilities of the AFM-SECM-electrode were tested with the nano-electrografting of vinylic monomers initiated by aryl diazonium salts. Nano-electrochemical and technical processes were thoroughly described, so as to allow experiments reproducing. A plausible explanation of chemical and electrochemical mechanisms, leading to the nano-grafting process, was reported. This combined technique represents the first step towards improved nano-processes for the nano-electrografting.

  20. Nano-Electrochemistry and Nano-Electrografting with an Original Combined AFM-SECM

    Science.gov (United States)

    Ghorbal, Achraf; Grisotto, Federico; Charlier, Julienne; Palacin, Serge; Goyer, Cédric; Demaille, Christophe; Ben Brahim, Ammar

    2013-01-01

    This study demonstrates the advantages of the combination between atomic force microscopy and scanning electrochemical microscopy. The combined technique can perform nano-electrochemical measurements onto agarose surface and nano-electrografting of non-conducting polymers onto conducting surfaces. This work was achieved by manufacturing an original Atomic Force Microscopy-Scanning ElectroChemical Microscopy (AFM-SECM) electrode. The capabilities of the AFM-SECM-electrode were tested with the nano-electrografting of vinylic monomers initiated by aryl diazonium salts. Nano-electrochemical and technical processes were thoroughly described, so as to allow experiments reproducing. A plausible explanation of chemical and electrochemical mechanisms, leading to the nano-grafting process, was reported. This combined technique represents the first step towards improved nano-processes for the nano-electrografting. PMID:28348337

  1. Localization of proteins in paint cross-sections by scanning electrochemical microscopy as an alternative immunochemical detection technique

    Energy Technology Data Exchange (ETDEWEB)

    Sciutto, Giorgia; Prati, Silvia [Microchemistry and Microscopy Art Diagnostic Laboratory, University of Bologna, Via Guaccimanni 42, Ravenna 48121 (Italy); Department of Chemistry “G. Ciamician”, University of Bologna, Via Selmi, Bologna 2 40126 (Italy); Mazzeo, Rocco, E-mail: rocco.mazzeo@unibo.it [Microchemistry and Microscopy Art Diagnostic Laboratory, University of Bologna, Via Guaccimanni 42, Ravenna 48121 (Italy); Department of Chemistry “G. Ciamician”, University of Bologna, Via Selmi, Bologna 2 40126 (Italy); Zangheri, Martina; Roda, Aldo; Bardini, Luca; Valenti, Giovanni; Rapino, Stefania [Department of Chemistry “G. Ciamician”, University of Bologna, Via Selmi, Bologna 2 40126 (Italy); Marcaccio, Massimo, E-mail: massimo.marcaccio@unibo.it [Department of Chemistry “G. Ciamician”, University of Bologna, Via Selmi, Bologna 2 40126 (Italy)

    2014-06-01

    Highlights: • Advanced immuno-electrochemical detection of proteins in paint samples by SECM. • Analysis performed directly on cross-section with high spatial resolution. • Identification of HRP catalytic activity for a selective location of analyte. • Satisfactory results were obtained for aged real samples. • The way forward for an extensive application of SECM in conservation science is shown. - Abstract: The qualitative identification of proteinaceous substances, as well as their location within a complex paint stratigraphy, is one of the most challenging issues in the characterization of painting materials. Nevertheless, information on paint components represent a crucial task for studies concerning both the ancient painting techniques adopted and the state of conservation, being fundamental investigations for the selection of appropriate conservation actions. The present research was aimed at developing a new detection approach for the immunochemical localization of ovalbumin in paint cross-sections based on the use of scanning electrochemical microscopy (SECM). The immunochemical analyses were performed using an anti-ovalbumin primary antibody and a secondary antibody labelled with horseradish peroxidase (HRP). SECM measurements were performed in feedback mode using benzoquinone (BQ)/hydroquinone (H{sub 2}Q) redox couple. In presence of hydrogen peroxide (H{sub 2}O{sub 2}), HRP catalyzes the re-oxidation of H{sub 2}Q to BQ and the increment of BQ concentration in correspondence of the target protein was detected by SECM through the electrochemical reduction of the regenerated BQ at the microelectrode. Indeed, the localization of ovalbumin was possible thanks to a clear discrimination of SECM currents, achieved by the comparison of the measurements recorded before and after H{sub 2}O{sub 2} administration, based on the HRP on/off approach. The method was evaluated both on samples from standard mocks-up and on a historical sample, collected from a

  2. Non-destructive Patterning of Carbon Electrodes by Using the Direct Mode of Scanning Electrochemical Microscopy.

    Science.gov (United States)

    Stratmann, Lutz; Clausmeyer, Jan; Schuhmann, Wolfgang

    2015-11-16

    Patterning of glassy carbon surfaces grafted with a layer of nitrophenyl moieties was achieved by using the direct mode of scanning electrochemical microscopy (SECM) to locally reduce the nitro groups to hydroxylamine and amino functionalities. SECM and atomic force microscopy (AFM) revealed that potentiostatic pulses applied to the working electrode lead to local destruction of the glassy carbon surface, most likely caused by etchants generated at the positioned SECM tip used as the counter electrode. By applying galvanostatic pulses, and thus, limiting the current during structuring, corrosion of the carbon surface was substantially suppressed. After galvanostatic patterning, unambiguous proof of the formation of the anticipated amino moieties was possible by modulation of the pH value during the feedback mode of SECM imaging. This patterning strategy is suitable for the further bio-modification of microstructured surfaces. Alkaline phosphatase, as a model enzyme, was locally bound to the modified areas, thus showing that the technique can be used for the development of protein microarrays. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Ultramicrosensors based on transition metal hexacyanoferrates for scanning electrochemical microscopy

    Directory of Open Access Journals (Sweden)

    Maria A. Komkova

    2013-10-01

    Full Text Available We report here a way for improving the stability of ultramicroelectrodes (UME based on hexacyanoferrate-modified metals for the detection of hydrogen peroxide. The most stable sensors were obtained by electrochemical deposition of six layers of hexacyanoferrates (HCF, more specifically, an alternating pattern of three layers of Prussian Blue and three layers of Ni–HCF. The microelectrodes modified with mixed layers were continuously monitored in 1 mM hydrogen peroxide and proved to be stable for more than 5 h under these conditions. The mixed layer microelectrodes exhibited a stability which is five times as high as the stability of conventional Prussian Blue-modified UMEs. The sensitivity of the mixed layer sensor was 0.32 A·M−1·cm−2, and the detection limit was 10 µM. The mixed layer-based UMEs were used as sensors in scanning electrochemical microscopy (SECM experiments for imaging of hydrogen peroxide evolution.

  4. Modelization of the SECM in molten salts environment

    International Nuclear Information System (INIS)

    Lucas, M.; Slim, C.; Di Caprio, D.; Delpech, S.; Stafiej, J.

    2013-01-01

    We develop a cellular automata simulation of SECM (Scanning Electrochemical Microscopy)experiments to study corrosion in molten salt media for generation IV nuclear reactors. The electrodes used in these experiments are cylindrical glass tips with a coaxial metal wire inside. As the result of simulations we obtain the current approach curves of the electrodes with geometries characterized by several values of the ratios of glass to metal area at the tip. We compare these results with predictions of the known analytic expressions, solutions of partial differential equations for flat uniform geometry of the substrate. We present also the results for other, more complicated substrate surface geometries e. g. regular saw modulated surface, or surface obtained by an Eden model process. We show that with a simple cellular automata model we can reasonably well simulate the results of SECM setup. The stochastic resolution of the diffusion equations is made possible by the parallel code implemented on GPU

  5. Surface Interrogation Scanning Electrochemical Microscopy for a Photoelectrochemical Reaction: Water Oxidation on a Hematite Surface.

    Science.gov (United States)

    Kim, Jae Young; Ahn, Hyun S; Bard, Allen J

    2018-03-06

    To understand the pathway of a photoelectrochemical (PEC) reaction, quantitative knowledge of reaction intermediates is important. We describe here surface interrogation scanning electrochemical microscopy for this purpose (PEC SI-SECM), where a light pulse to a photoactive semiconductor film at a given potential generates intermediates that are then analyzed by a tip generated titrant at known times after the light pulse. The improvements were demonstrated for photoelectrochemical water oxidation (oxygen evolution) reaction on a hematite surface. The density of photoactive sites, proposed to be Fe 4+ species, on a hematite surface was successfully quantified, and the photoelectrochemical water oxidation reaction dynamics were elucidated by time-dependent redox titration experiments. The new configuration of PEC SI-SECM should find expanded usage to understand and investigate more complicated PEC reactions with other materials.

  6. Imaging by Electrochemical Scanning Tunneling Microscopy and Deconvolution Resolving More Details of Surfaces Nanomorphology

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    observed in high-resolution images of metallic nanocrystallites may be effectively deconvoluted, as to resolve more details of the crystalline morphology (see figure). Images of surface-crystalline metals indicate that more than a single atomic layer is involved in mediating the tunneling current......Upon imaging, electrochemical scanning tunneling microscopy (ESTM), scanning electrochemical micro-scopy (SECM) and in situ STM resolve information on electronic structures and on surface topography. At very high resolution, imaging processing is required, as to obtain information that relates...... to crystallographic-surface structures. Within the wide range of new technologies, those images surface features, the electrochemical scanning tunneling microscope (ESTM) provides means of atomic resolution where the tip participates actively in the process of imaging. Two metallic surfaces influence ions trapped...

  7. Detection of CO2•- in the Electrochemical Reduction of Carbon Dioxide in N,N-Dimethylformamide by Scanning Electrochemical Microscopy.

    Science.gov (United States)

    Kai, Tianhan; Zhou, Min; Duan, Zhiyao; Henkelman, Graeme A; Bard, Allen J

    2017-12-27

    The electrocatalytic reduction of CO 2 has been studied extensively and produces a number of products. The initial reaction in the CO 2 reduction is often taken to be the 1e formation of the radical anion, CO 2 •- . However, the electrochemical detection and characterization of CO 2 •- is challenging because of the short lifetime of CO 2 •- , which can dimerize and react with proton donors and even mild oxidants. Here, we report the generation and quantitative determination of CO 2 •- in N,N-dimethylformamide (DMF) with the tip generation/substrate collection (TG/SC) mode of scanning electrochemical microscopy (SECM). CO 2 was reduced at a hemisphere-shaped Hg/Pt ultramicroelectrode (UME) or a Hg/Au film UME, which were utilized as the SECM tips. The CO 2 •- produced can either dimerize to form oxalate within the nanogap between SECM tip and substrate or collected at SECM substrate (e.g., an Au UME). The collection efficiency (CE) for CO 2 •- depends on the distance (d) between the tip and substrate. The dimerization rate (6.0 × 10 8 M -1 s -1 ) and half-life (10 ns) of CO 2 •- can be evaluated by fitting the collection efficiency vs distance curve. The dimerized species of CO 2 •- , oxalate, can also be determined quantitatively. Furthermore, the formal potential (E 0 ') and heterogeneous rate constant (k 0 ) for CO 2 reduction were determined with different quaternary ammonium electrolytes. The significant difference in k 0 is due to a tunneling effect caused by the adsorption of the electrolytes on the electrode surface at negative potentials.

  8. Fabrication of cone-shaped boron doped diamond and gold nanoelectrodes for AFM-SECM

    Energy Technology Data Exchange (ETDEWEB)

    Avdic, A; Lugstein, A; Bertagnolli, E [Solid State Electronics Institute, Vienna University of Technology, Floragasse 7, 1040 Vienna (Austria); Wu, M; Gollas, B [Competence Centre for Electrochemical Surface Technology, Viktor Kaplan Strasse 2, 2700 Wiener Neustadt (Austria); Pobelov, I; Wandlowski, T [Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern (Switzerland); Leonhardt, K; Denuault, G, E-mail: alois.lugstein@tuwien.ac.at [School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom)

    2011-04-08

    We demonstrate a reliable microfabrication process for a combined atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM) measurement tool. Integrated cone-shaped sensors with boron doped diamond (BDD) or gold (Au) electrodes were fabricated from commercially available AFM probes. The sensor formation process is based on mature semiconductor processing techniques, including focused ion beam (FIB) machining, and highly selective reactive ion etching (RIE). The fabrication approach preserves the geometry of the original AFM tips resulting in well reproducible nanoscaled sensors. The feasibility and functionality of the fully featured tips are demonstrated by cyclic voltammetry, showing good agreement between the measured and calculated currents of the cone-shaped AFM-SECM electrodes.

  9. Scanning electrochemical microscopy for the fabrication of copper nanowires: Atomic contacts with quantized conductance, and molecular adsorption effect

    International Nuclear Information System (INIS)

    Janin, Marion; Ghilane, Jalal; Lacroix, Jean-Christophe

    2012-01-01

    Highlights: ► Electrochemistry and SECM to generate copper nanowires with quantized conductance. ► Stable atomic contacts lasting for several hundreds of seconds have been obtained. ► The quantized conductances are independent of the tip and gap size. ► The method allows contacts to be generated in the presence of chosen molecules. ► Four-electrode configuration opens the route to redox gated atomic contact. - Abstract: Scanning electrochemical microscopy, SECM, is proposed as a tool for the fabrication of copper nanowires. In a first step, configuration based on two electrodes, a platinum UME (cathode) and a copper substrate (anode), operating in the SECM configuration was employed. For nanowires generated in water the conductance changes stepwise and varies by integer values of the conductance quantum G 0 . The formation of atomic contacts is supported by the ohmic behavior of the I–V curve. It depends neither on the UME tip radius nor on the initial gap size between tip and substrate. Atomic contacts generated in aqueous solutions of sodium dodecyl sulfate (SDS) below the critical micellar concentration (CMC) have conductances below 1G 0 attributed to molecular adsorption on the contact. In some cases, the nanowires have low conductance, 0.01G 0 . The corresponding I–V curve shows tunneling rather than ohmic behavior, suggesting that molecular junctions are formed with a few surfactant molecules trapped between the two electrodes. Finally, copper nanowires with quantized conductance have been generated using the SECM operating in a four-electrode setup. Thanks to the reference electrode, this configuration leads to better control of the potential of each working electrode; this setup will make it possible to evaluate the conductance variation and/or modulation upon electrochemical stimuli.

  10. Development of scanning electrochemical microscopy for the investigation of photocatalysis at semiconductor surfaces

    International Nuclear Information System (INIS)

    Fonseca, Sofia Margarida Martins Costa da

    2002-01-01

    This thesis is concerned with the development and application of scanning electrochemical microscopy (SECM) to investigate interfacial photoelectrochemical processes occurring at supported TiO 2 surfaces. The new SECM approach, involving both amperometric and potentiometric electrodes, was used to monitor interfacial photoprocesses with high spatial resolution. A new in situ photoelectrochemical approach to chemical actinometry has been developed and used to determine the light flux through a quartz fibre employed in the SECM system. In this system an ultramicroelectrode (UME) probe is positioned with high precision at a known distance close to a TiO 2 -coated fibre and used to detect reactants or products of the ongoing photodegradation process. The microelectrochemical actinometry approach was developed using the well-known liquid phase potassium ferrioxalate actinometer. The approach involved recording the steady-state current for Fe(lll) reduction at an SECM tip positioned close to the fibre. A step function in the light flux (off-on) was then applied and the resulting chronoamperometric behaviour due to the reduction of Fe(lll) at the UME was recorded as a function of tip-fibre separation distance. A theoretical model has been developed to simulate experimental current-time profiles, which allowed the light flux through the quartz fibre to be quantified. An experimental approach to investigating the photoelectrochemical reduction of oxygen at UV-illuminated TiO 2 surfaces, in aqueous aerated and oxygenated electrolyte solutions, in the absence and presence of hole scavengers, has been developed. In this new approach the chronoamperometric behaviour for oxygen reduction was recorded at an UME tip after stepping the light flux at a back-illuminated TiO 2 film on and off. The kinetics of the reduction process were interpreted through various theoretical models proposed in the literature. This experimental approach demonstrated a significant depletion of the

  11. Electron transfer kinetics of cytochrome c immobilized on a phenolic terminated thiol self assembled monolayer determined by scanning electrochemical microscopy

    International Nuclear Information System (INIS)

    Alizadeh, Vali; Mousavi, Mir Fazlollah; Mehrgardi, Masoud Ayatollahi; Kazemi, Sayed Habib; Sharghi, Hashem

    2011-01-01

    Highlights: → Preparing a thiolated phenolic self-assembled monolayer surface (SAM). → Application of this SAM to immobilize cytochrome C. → Scanning electrochemical microscopy used for these studies. → Determination of both tunneling electron transfer and bimolecular rate constants between the immobilized protein-substrate and probe. - Abstract: In the present manuscript, the electrochemical behavior of cytochrome c (cyt-c) immobilized onto a phenolic terminated self assembled monolayer (SAM) on a gold electrode is investigated using cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM). The tunneling electron transfer (ET) rate constant between the immobilized protein and the underlying electrode surface, and also the bimolecular ET rate constant between the immobilized protein and a probe has been obtained using approach curves that were obtained by SECM. The approach curves were recorded at different substrate overpotentials in the presence of various concentrations of ferrocyanide as a probe and various surface concentrations of cyt-c; then the standard tunneling ET and bimolecular rate constants are obtained as 3.4 ± 0.3 s -1 and (2.0 ± 0.5) x 10 7 cm 3 mol -1 s -1 , respectively.

  12. Electron transfer kinetics of cytochrome c immobilized on a phenolic terminated thiol self assembled monolayer determined by scanning electrochemical microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, Vali [Department of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Mousavi, Mir Fazlollah, E-mail: mousavim@modares.ac.ir [Department of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Mehrgardi, Masoud Ayatollahi [Department of Chemistry, University of Isfahan, Isfahan (Iran, Islamic Republic of); Kazemi, Sayed Habib [Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan (Iran, Islamic Republic of); Sharghi, Hashem [Department of Chemistry, Shiraz University, Shiraz (Iran, Islamic Republic of)

    2011-07-01

    Highlights: > Preparing a thiolated phenolic self-assembled monolayer surface (SAM). > Application of this SAM to immobilize cytochrome C. > Scanning electrochemical microscopy used for these studies. > Determination of both tunneling electron transfer and bimolecular rate constants between the immobilized protein-substrate and probe. - Abstract: In the present manuscript, the electrochemical behavior of cytochrome c (cyt-c) immobilized onto a phenolic terminated self assembled monolayer (SAM) on a gold electrode is investigated using cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM). The tunneling electron transfer (ET) rate constant between the immobilized protein and the underlying electrode surface, and also the bimolecular ET rate constant between the immobilized protein and a probe has been obtained using approach curves that were obtained by SECM. The approach curves were recorded at different substrate overpotentials in the presence of various concentrations of ferrocyanide as a probe and various surface concentrations of cyt-c; then the standard tunneling ET and bimolecular rate constants are obtained as 3.4 {+-} 0.3 s{sup -1} and (2.0 {+-} 0.5) x 10{sup 7} cm{sup 3} mol{sup -1} s{sup -1}, respectively.

  13. Determining Li+-Coupled Redox Targeting Reaction Kinetics of Battery Materials with Scanning Electrochemical Microscopy.

    Science.gov (United States)

    Yan, Ruiting; Ghilane, Jalal; Phuah, Kia Chai; Pham Truong, Thuan Nguyen; Adams, Stefan; Randriamahazaka, Hyacinthe; Wang, Qing

    2018-02-01

    The redox targeting reaction of Li + -storage materials with redox mediators is the key process in redox flow lithium batteries, a promising technology for next-generation large-scale energy storage. The kinetics of the Li + -coupled heterogeneous charge transfer between the energy storage material and redox mediator dictates the performance of the device, while as a new type of charge transfer process it has been rarely studied. Here, scanning electrochemical microscopy (SECM) was employed for the first time to determine the interfacial charge transfer kinetics of LiFePO 4 /FePO 4 upon delithiation and lithiation by a pair of redox shuttle molecules FcBr 2 + and Fc. The effective rate constant k eff was determined to be around 3.70-6.57 × 10 -3 cm/s for the two-way pseudo-first-order reactions, which feature a linear dependence on the composition of LiFePO 4 , validating the kinetic process of interfacial charge transfer rather than bulk solid diffusion. In addition, in conjunction with chronoamperometry measurement, the SECM study disproves the conventional "shrinking-core" model for the delithiation of LiFePO 4 and presents an intriguing way of probing the phase boundary propagations induced by interfacial redox reactions. This study demonstrates a reliable method for the kinetics of redox targeting reactions, and the results provide useful guidance for the optimization of redox targeting systems for large-scale energy storage.

  14. Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

    Directory of Open Access Journals (Sweden)

    Sanju Gupta

    2015-10-01

    Full Text Available Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO1, (PPy/ErGO1, (PAni/GO1 and (PPy/GO1. The rationale design is to create thin films that possess interconnected graphene nanosheets (GNS with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, Cs, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent Cs of ≥350 F g−1 as compared with constituents (∼70 F g−1 at discharge current density of 0.3 A g−1 that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting and conducting polymers (semiconducting backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine electrochemical (reactivity of surface ion

  15. Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Sanju, E-mail: sanju.gupta@wku.edu; Price, Carson [Department of Physics and Astronomy, Western Kentucky University, 1906 College Heights Blvd., Bowling Green, KY 42101-3576 (United States)

    2015-10-15

    Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL) assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO){sub 1}, (PPy/ErGO){sub 1}, (PAni/GO){sub 1} and (PPy/GO){sub 1}. The rationale design is to create thin films that possess interconnected graphene nanosheets (GNS) with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, C{sub s}, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent C{sub s} of ≥350 F g{sup −1} as compared with constituents (∼70 F g{sup −1}) at discharge current density of 0.3 A g{sup −1} that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM) technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting) and conducting polymers (semiconducting) backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine

  16. Scanning electrochemical microscopy of graphene/polymer hybrid thin films as supercapacitors: Physical-chemical interfacial processes

    Science.gov (United States)

    Gupta, Sanju; Price, Carson

    2015-10-01

    Hybrid electrode comprising an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the electrically conducting polymers namely, polyaniline; PAni and polypyrrole; PPy are constructed that exhibited synergistic effect with excellent electrochemical performance as thin film supercapacitors for alternative energy. The hybrid supercapacitors were prepared by layer-by-layer (LbL) assembly based on controlled electrochemical polymerization followed by reduction of graphene oxide electrochemically producing ErGO, for establishing intimate electronic contact through nanoscale architecture and chemical stability, producing a single bilayer of (PAni/ErGO)1, (PPy/ErGO)1, (PAni/GO)1 and (PPy/GO)1. The rationale design is to create thin films that possess interconnected graphene nanosheets (GNS) with polymer nanostructures forming well-defined tailored interfaces allowing sufficient surface adsorption and faster ion transport due to short diffusion distances. We investigated their electrochemical properties and performance in terms of gravimetric specific capacitance, Cs, from cyclic voltammograms. The LbL-assembled bilayer films exhibited an excellent Cs of ≥350 F g-1 as compared with constituents (˜70 F g-1) at discharge current density of 0.3 A g-1 that outperformed many other hybrid supercapacitors. To gain deeper insights into the physical-chemical interfacial processes occurring at the electrode/electrolyte interface that govern their operation, we have used scanning electrochemical microscopy (SECM) technique in feedback and probe approach modes. We present our findings from viewpoint of reinforcing the role played by heterogeneous electrode surface composed of nanoscale graphene sheets (conducting) and conducting polymers (semiconducting) backbone with ordered polymer chains via higher/lower probe current distribution maps. Also targeted is SECM imaging that allowed to determine electrochemical (re)activity of surface ion adsorption sites

  17. Intermittent Contact Alternating Current Scanning Electrochemical Microscopy: A Method for Mapping Conductivities in Solid Li Ion Conducting Electrolyte Samples

    Energy Technology Data Exchange (ETDEWEB)

    Catarelli, Samantha Raisa; Lonsdale, Daniel [Uniscan Instruments Ltd., Macclesfield (United Kingdom); Cheng, Lei [Energy Storage and Distribution Resources Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Materials Sciences and Engineering Department, University of California Berkeley, Berkeley, CA (United States); Syzdek, Jaroslaw [Bio-Logic USA LLC, Knoxville, TN (United States); Doeff, Marca, E-mail: mmdoeff@lbl.gov [Energy Storage and Distribution Resources Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

    2016-03-31

    Intermittent contact alternating current scanning electrochemical microscopy (ic-ac-SECM) has been used to determine the electrochemical response to an ac signal of several types of materials. A conductive gold foil and insulating Teflon sheet were first used to demonstrate that the intermittent contact function allows the topography and conductivity to be mapped simultaneously and independently in a single experiment. Then, a dense pellet of an electronically insulating but Li ion conducting garnet phase, Al-substituted Li{sub 7}La{sub 3}Zr{sub 2}O{sub 12} (LLZO), was characterized using the same technique. The polycrystalline pellet was prepared by classical ceramic sintering techniques and was comprised of large (~150 μm) grains. Critical information regarding the contributions of grain and grain boundary resistances to the total conductivity of the garnet phase was lacking due to ambiguities in the impedance data. In contrast, the use of the ic-ac-SECM technique allowed spatially resolved information regarding local conductivities to be measured directly. Impedance mapping of the pellet showed that the grain boundary resistance, while generally higher than that of grains, varied considerably, revealing the complex nature of the LLZO sample.

  18. Kelvin probe force microscopy in liquid using electrochemical force microscopy

    Directory of Open Access Journals (Sweden)

    Liam Collins

    2015-01-01

    Full Text Available Conventional closed loop-Kelvin probe force microscopy (KPFM has emerged as a powerful technique for probing electric and transport phenomena at the solid–gas interface. The extension of KPFM capabilities to probe electrostatic and electrochemical phenomena at the solid–liquid interface is of interest for a broad range of applications from energy storage to biological systems. However, the operation of KPFM implicitly relies on the presence of a linear lossless dielectric in the probe–sample gap, a condition which is violated for ionically-active liquids (e.g., when diffuse charge dynamics are present. Here, electrostatic and electrochemical measurements are demonstrated in ionically-active (polar isopropanol, milli-Q water and aqueous NaCl and ionically-inactive (non-polar decane liquids by electrochemical force microscopy (EcFM, a multidimensional (i.e., bias- and time-resolved spectroscopy method. In the absence of mobile charges (ambient and non-polar liquids, KPFM and EcFM are both feasible, yielding comparable contact potential difference (CPD values. In ionically-active liquids, KPFM is not possible and EcFM can be used to measure the dynamic CPD and a rich spectrum of information pertaining to charge screening, ion diffusion, and electrochemical processes (e.g., Faradaic reactions. EcFM measurements conducted in isopropanol and milli-Q water over Au and highly ordered pyrolytic graphite electrodes demonstrate both sample- and solvent-dependent features. Finally, the feasibility of using EcFM as a local force-based mapping technique of material-dependent electrostatic and electrochemical response is investigated. The resultant high dimensional dataset is visualized using a purely statistical approach that does not require a priori physical models, allowing for qualitative mapping of electrostatic and electrochemical material properties at the solid–liquid interface.

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

    Science.gov (United States)

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

    2018-06-18

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

  20. Reaction of Br2 with adsorbed CO on Pt, studied by the surface interrogation mode of scanning electrochemical microscopy.

    Science.gov (United States)

    Wang, Qian; Rodríguez-López, Joaquín; Bard, Allen J

    2009-12-02

    Scanning electrochemical microscopy surface interrogation (SI-SECM) in the cyclic voltammetry mode was successfully used to detect and quantify adsorbed CO on a Pt electrode by reaction with electrogenerated Br(2). The two-electrode setup used in this new technique allowed the production of Br(2) on an interrogator tip, which reported a transient positive feedback above a Pt substrate at open circuit as an indication of the reactivity of this halogen with CO((ads)). Br(-) and CO(2) are shown to be the main products of the reaction (in the absence of O(2)), which may involve the formation of bromophosgene as a hydrolyzable intermediate. Under saturation conditions, CO((ads)) was reproducibly quantified at the polycrystalline Pt surface with theta(CO) approximately = 0.5. The reaction is shown to be blocked by the action of pre-adsorbed cyanide, which demonstrates the surface character of the process. The formation of CO(2) as an end product was further tested in a bulk experiment: addition of Pt black to a mixture of Br(2) in 0.5 M H(2)SO(4) through which CO was bubbled gave a precipitate of BaCO(3) in a saturated solution of Ba(OH)(2). The use of SI-SECM allowed access to a reaction that would otherwise be difficult to prove through conventional electrochemistry on a single electrode.

  1. A new application of scanning electrochemical microscopy for the label-free interrogation of antibody-antigen interactions

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, Joanne L.; Davis, Frank; Collyer, Stuart D. [Cranfield Health, Cranfield University, Cranfield, MK43 0AL (United Kingdom); Higson, Seamus P.J., E-mail: s.p.j.higson@cranfield.ac.uk [Cranfield Health, Cranfield University, Cranfield, MK43 0AL (United Kingdom)

    2011-03-18

    Within this work we present a 'proof of principle' study for the use of scanning electrochemical microscopy (SECM) to detect and image biomolecular interactions in a label-free assay as a potential alternative to current fluorescence techniques. Screen-printed carbon electrodes were used as the substrate for the deposition of a dotted array, where the dots consist of biotinylated polyethyleneimine. These were then further derivatised, first with neutravidin and then with a biotinylated antibody to the protein neuron specific enolase (NSE). SECM using a ferrocene carboxylic acid mediator showed clear differences between the array and the surrounding unmodified carbon. Imaging of the arrays before and following exposure to various concentrations of the antigen showed clear evidence for specific binding of the NSE antigen to the antibody derivatised dots. Non-specific binding was quantified. Control experiments with other proteins showed only non-specific binding across the whole of the substrate, thereby confirming that specific binding does occur between the antibody and antigen at the surface of the dots. Binding of the antigen was accompanied by a measured increase in current response, which may be explained in terms of protein electrostatic interaction and hydrophobic interactions to the mediator, thereby increasing the localised mediator flux. A calibration curve was obtained between 500 fg mL{sup -1} to 200 pg mL{sup -1} NSE which demonstrated a logarithmic relationship between the current change upon binding and antigen concentration without the need for any labelling of the substrate.

  2. Direct evidence of ionic fluxes across ion-selective membranes: a scanning electrochemical microscopic and potentiometric study.

    Science.gov (United States)

    Gyurcsányi, R E; Pergel, E; Nagy, R; Kapui, I; Lan, B T; Tóth, K; Bitter, I; Lindner, E

    2001-05-01

    Scanning electrochemical microscopy (SECM) supplemented with potentiometric measurements was used to follow the time-dependent buildup of a steady-state diffusion layer at the aqueous-phase boundary of lead ion-selective electrodes (ISEs). Differential pulse voltammetry is adapted to SECM for probing the local concentration profiles at the sample side of solvent polymeric membranes. Major factors affecting the membrane transport-related surface concentrations were identified from SECM data and the potentiometric transients obtained under different experimental conditions (inner filling solution composition, membrane thickness, surface pretreatment). The amperometrically determined surface concentrations correlated well with the lower detection limits of the lead ion-selective electrodes.

  3. Cyclic voltammetry and scanning electrochemical microscopy studies of methylene blue immobilized on the self-assembled monolayer of n-dodecanethiol

    International Nuclear Information System (INIS)

    Salamifar, Seyed Ehsan; Mehrgardi, Masoud Ayatollahi; Kazemi, Sayed Habib; Mousavi, Mir Fazllollah

    2010-01-01

    Electron transfer (ET) kinetics through n-dodecanethiol (C 12 SH) self-assembled monolayer on gold electrode was studied using cyclic voltammetry (CV), scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS). An SECM model for compensating pinhole contribution, was used to measure the ET kinetics of solution-phase probes of ferrocyanide/ferricyanide (Fe(CN) 6 4-/3- ) and ferrocenemethanol/ferrociniummethanol (FMC 0/+ ) through the C 12 SH monolayer yielding standard tunneling rate constant (k ET 0 ) of (4 ± 1) x 10 -11 and (3 ± 1) x 10 -10 cm s -1 for Fe(CN) 6 4-/3- and FMC 0/+ respectively. Decay tunneling constants (β) of 0.97 and 0.96 A -1 for saturated alkane thiol chains were obtained using Fe(CN) 6 4- and FMC respectively. Also, it was found that methylene blue (MB) molecules are effectively immobilized on the C 12 SH monolayer and can mediate the ET between the solution-phase probes and underlying gold substrate. SECM-mediated model was used to simultaneously measure the bimolecular ET between the solution-phase probes and the monolayer-immobilized MB molecules, as well as tunneling ET between the monolayer-immobilized MB molecules and the underlying gold electrode, allowing the measurement of k BI = (5 ± 1) x 10 6 and (4 ± 2) x 10 7 cm 3 mol -1 s -1 for the bimolecular ET and k ET/MB 0 =(1±0.3)x10 -3 and (7 ± 3) x 10 -2 s -1 for the standard tunneling rate constant of ET using Fe(CN) 6 4-/3- and FMC 0/+ probes respectively.

  4. Cyclic voltammetry and scanning electrochemical microscopy studies of methylene blue immobilized on the self-assembled monolayer of n-dodecanethiol

    Energy Technology Data Exchange (ETDEWEB)

    Salamifar, Seyed Ehsan [Department of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of); Mehrgardi, Masoud Ayatollahi [Department of Chemistry, University of Isfahan, Isfahan (Iran, Islamic Republic of); Kazemi, Sayed Habib [Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan (Iran, Islamic Republic of); Mousavi, Mir Fazllollah, E-mail: mousavim@modares.ac.i [Department of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran (Iran, Islamic Republic of)

    2010-12-30

    Electron transfer (ET) kinetics through n-dodecanethiol (C{sub 12}SH) self-assembled monolayer on gold electrode was studied using cyclic voltammetry (CV), scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS). An SECM model for compensating pinhole contribution, was used to measure the ET kinetics of solution-phase probes of ferrocyanide/ferricyanide (Fe(CN){sub 6}{sup 4-/3-}) and ferrocenemethanol/ferrociniummethanol (FMC{sup 0/+}) through the C{sub 12}SH monolayer yielding standard tunneling rate constant (k{sub ET}{sup 0}) of (4 {+-} 1) x 10{sup -11} and (3 {+-} 1) x 10{sup -10} cm s{sup -1} for Fe(CN){sub 6}{sup 4-/3-} and FMC{sup 0/+} respectively. Decay tunneling constants ({beta}) of 0.97 and 0.96 A{sup -1} for saturated alkane thiol chains were obtained using Fe(CN){sub 6}{sup 4-} and FMC respectively. Also, it was found that methylene blue (MB) molecules are effectively immobilized on the C{sub 12}SH monolayer and can mediate the ET between the solution-phase probes and underlying gold substrate. SECM-mediated model was used to simultaneously measure the bimolecular ET between the solution-phase probes and the monolayer-immobilized MB molecules, as well as tunneling ET between the monolayer-immobilized MB molecules and the underlying gold electrode, allowing the measurement of k{sub BI} = (5 {+-} 1) x 10{sup 6} and (4 {+-} 2) x 10{sup 7} cm{sup 3} mol{sup -1} s{sup -1} for the bimolecular ET and k{sub ET/MB}{sup 0}=(1{+-}0.3)x10{sup -3} and (7 {+-} 3) x 10{sup -2} s{sup -1} for the standard tunneling rate constant of ET using Fe(CN){sub 6}{sup 4-/3-} and FMC{sup 0/+} probes respectively.

  5. A Study of the Mechanism of the Hydrogen Evolution Reaction on Nickel by Surface Interrogation Scanning Electrochemical Microscopy.

    Science.gov (United States)

    Liang, Zhenxing; Ahn, Hyun S; Bard, Allen J

    2017-04-05

    The hydrogen evolution reaction (HER) on Ni in alkaline media was investigated by scanning electrochemical microscopy under two operating modes. First, the substrate generation/tip collection mode was employed to extract the "true" cathodic current associated with the HER from the total current in the polarization curve. Compared to metallic Ni, the electrocatalytic activity of the HER is improved in the presence of the low-valence-state oxide of Ni. This result is in agreement with a previous claim that the dissociative adsorption of water can be enhanced at the Ni/Ni oxide interface. Second, the surface-interrogation scanning electrochemical microscopy (SI-SECM) mode was used to directly measure the coverage of the adsorbed hydrogen on Ni at given potentials. Simulation indicates that the hydrogen coverage follows a Frumkin isotherm with respect to the applied potential. On the basis of the combined analysis of the Tafel slope and surface hydrogen coverage, the rate-determining step is suggested to be the adsorption of hydrogen (Volmer step) in the investigated potential window.

  6. Observation of Dynamic Interfacial Layers in Li-Ion and Li-O_2 Batteries by Scanning Electrochemical Microscopy

    International Nuclear Information System (INIS)

    Bülter, Heinz; Schwager, Patrick; Fenske, Daniela; Wittstock, Gunther

    2016-01-01

    Highlights: • Imaging changes of solid electrolyte interphases on rinsed lithiated graphite. • Strongly non-uniform changes of SEI passivation properties. • In situ imaging of clogged gas diffusion electrodes of Li/O_2 batteries. - Abstract: The requirements of high energy density in modern batteries dictate the use of very high (oxidizing) or very low (reducing) potential for negative and positive electrode materials. These extreme potentials can cause molecular compounds to undergo electron transfer reactions at the interfaces. This is well documented for lithium-ion batteries, where a solid electrolyte interphase (SEI) between the lithiated graphite electrode and the electrolyte is formed by the decomposition of electrolyte components mainly during the first charging process. Characterization of the SEI is a challenge because of the variety of chemically similar components and enclosed electrolyte species. Furthermore, ex situ analysis of the SEI requires separation and isolation of the SEI, which may change the content and the structure of the SEI. Scanning electrochemical microscopy (SECM) provides in situ analysis of passivating layers formed at battery electrodes. Such approaches must deal with continuous changes of the studied interfaces. This is illustrated for the in situ investigation of the electron transport at SEI-covered lithiated graphite using 2,5-di-tert-butyl-1,4-dimethoxy benzene as SECM mediator in an inert atmosphere. With this setup, the influence of rinsing protocols on the passivating properties of the SEI was studied. An extensive rinsing compared to our previous studies [DOI 10.1002/anie.201403935] leads to much higher local variation of the SEI passivation properties which continue over the entire observation time of 54 h. The second example uses a SECM generation-collection experiment to detect gas permeation through a gas-diffusion electrode (GDE) of a Li-O_2 cell into a Li"+-containing organic electrolyte. The passivation of the

  7. Fabrication and characterization of a nanometer-sized optical fiber electrode based on selective chemical etching for scanning electrochemical/optical microscopy.

    Science.gov (United States)

    Maruyama, Kenichi; Ohkawa, Hiroyuki; Ogawa, Sho; Ueda, Akio; Niwa, Osamu; Suzuki, Koji

    2006-03-15

    We have already reported a method for fabricating ultramicroelectrodes (Suzuki, K. JP Patent, 2004-45394, 2004). This method is based on the selective chemical etching of optical fibers. In this work, we undertake a detailed investigation involving a combination of etched optical fibers with various types of tapered tip (protruding-shape, double- (or pencil-) shape and triple-tapered electrode) and insulation with electrophoretic paint. Our goal is to establish a method for fabricating nanometer-sized optical fiber electrodes with high reproducibility. As a result, we realized pencil-shaped and triple-tapered electrodes that had radii in the nanometer range with high reproducibility. These nanometer-sized electrodes showed well-defined sigmoidal curves and stable diffusion-limited responses with cyclic voltammetry. The pencil-shaped optical fiber, which has a conical tip with a cone angle of 20 degrees , was effective for controlling the electrode radius. The pencil-shaped electrodes had higher reproducibility and smaller electrode radii (r(app) etched optical fiber electrodes. By using a pencil-shaped electrode with a 105-nm radius as a probe, we obtained simultaneous electrochemical and optical images of an implantable interdigitated array electrode. We achieved nanometer-scale resolution with a combination of scanning electrochemical microscopy SECM and optical microscopy. The resolution of the electrochemical and optical images indicated sizes of 300 and 930 nm, respectively. The neurites of living PC12 cells were also successfully imaged on a 1.6-microm scale by using the negative feedback mode of an SECM.

  8. Scanning electrochemical microscopy. 47. Imaging electrocatalytic activity for oxygen reduction in an acidic medium by the tip generation-substrate collection mode.

    Science.gov (United States)

    Fernández, José L; Bard, Allen J

    2003-07-01

    The oxygen reduction reaction (ORR) in acidic medium was studied on different electrode materials by scanning electrochemical microscopy (SECM) operating in a new variation of the tip generation-substrate collection mode. An ultramicroelectrode tip placed close to the substrate electrode oxidizes water to oxygen at a constant current. The substrate is held at a potential where the tip-generated oxygen is reduced and the resulting substrate current is measured. By changing the substrate potential, it is possible to obtain a polarization (current-potential) curve, which depends on the electrocatalytic activity of the substrate material. The main difference between this mode and the classical feedback SECM mode of operation is that the feedback diffusion process is not required for the measurement, allowing its application for studying the ORR in acidic solutions. Activity-sensitive images of heterogeneous surfaces, e.g., with Pt and Au electrodes, were obtained from the substrate current when the x-y plane was scanned with the tip. The usefulness of this technique for imaging electrocatalytic activity of smooth metallic electrodes and of highly dispersed fuel cell-type electrocatalysts was demonstrated. The application of this method to the combinatorial chemical analysis of electrode materials and electrocatalysts is discussed.

  9. Menadione metabolism to thiodione in hepatoblastoma by scanning electrochemical microscopy

    Science.gov (United States)

    Mauzeroll, Janine; Bard, Allen J.; Owhadian, Omeed; Monks, Terrence J.

    2004-01-01

    The cytotoxicity of menadione on hepatocytes was studied by using the substrate generation/tip collection mode of scanning electrochemical microscopy by exposing the cells to menadione and detecting the menadione-S-glutathione conjugate (thiodione) that is formed during the cellular detoxication process and is exported from the cell by an ATP-dependent pump. This efflux was electrochemically detected and allowed scanning electrochemical microscopy monitoring and imaging of single cells and groups of highly confluent live cells. Based on a constant flux model, ≈6 × 106 molecules of thiodione per cell per second are exported from monolayer cultures of Hep G2 cells. PMID:15601769

  10. Real-time monitoring of quorum sensing in 3D-printed bacterial aggregates using scanning electrochemical microscopy.

    Science.gov (United States)

    Connell, Jodi L; Kim, Jiyeon; Shear, Jason B; Bard, Allen J; Whiteley, Marvin

    2014-12-23

    Microbes frequently live in nature as small, densely packed aggregates containing ∼10(1)-10(5) cells. These aggregates not only display distinct phenotypes, including resistance to antibiotics, but also, serve as building blocks for larger biofilm communities. Aggregates within these larger communities display nonrandom spatial organization, and recent evidence indicates that this spatial organization is critical for fitness. Studying single aggregates as well as spatially organized aggregates remains challenging because of the technical difficulties associated with manipulating small populations. Micro-3D printing is a lithographic technique capable of creating aggregates in situ by printing protein-based walls around individual cells or small populations. This 3D-printing strategy can organize bacteria in complex arrangements to investigate how spatial and environmental parameters influence social behaviors. Here, we combined micro-3D printing and scanning electrochemical microscopy (SECM) to probe quorum sensing (QS)-mediated communication in the bacterium Pseudomonas aeruginosa. Our results reveal that QS-dependent behaviors are observed within aggregates as small as 500 cells; however, aggregates larger than 2,000 bacteria are required to stimulate QS in neighboring aggregates positioned 8 μm away. These studies provide a powerful system to analyze the impact of spatial organization and aggregate size on microbial behaviors.

  11. A study of ion exchange at the poly(butyl viologen)-electrolyte interface by SECM

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Chih-Yu.; Vasantha, V.S. [Department of Chemical Engineering, National Taiwan University, Taipei 10617 (China); Ho, Kuo-Chuan [Department of Chemical Engineering, National Taiwan University, Taipei 10617 (China); Institute of Polymer Science and Engineering, National Taiwan University, Taipei 10617 (China)

    2008-09-01

    In this work, the ion exchange characteristics of poly(butyl viologen) (PBV) thin films on a platinum electrode has been investigated by cyclic voltammetric (CV) scans. Since ferrocyanide anions (Fe(CN){sub 6}{sup 4-}) were added during the polymerization of the PBV thin-film for its stability, Fe(CN){sub 6}{sup 4-} could form charge transfer complex with monomer and co-deposited with polymer. Scanning electrochemical microscopy (SECM) was used to probe the released Fe(CN){sub 6}{sup 4-} ions from PBV film with Os(bpy){sub 3}Cl{sub 2} as a mediator for the approaching process in 0.5 M KCl medium. Mass changes during the redox process of the film were also monitored in-situ by electrochemical quartz crystal microbalance (EQCM). The ion exchange and transport behavior was observed during CV cycling of the film of the SECM and EQCM. The insertion and extraction of anions were found to be potential-dependence. Moreover, the decrease in tip current of released Fe(CN){sub 6}{sup 4-} with increasing cycle number accounted for the ion exchange between Fe(CN){sub 6}{sup 4-} and Cl{sup -} in the KCl electrolyte. However, the Fe(CN){sub 6}{sup 4-}/Fe(CN){sub 6}{sup 3-} redox couple was found to be highly stable between 0.0 and 0.5 V (vs. Ag/AgCl/saturated KCl) in the phosphate buffer solution. Therefore, the electrochemical property of Fe(CN){sub 6}{sup 4-}/Fe(CN){sub 6}{sup 3-} redox couple was studied at different scan rates using CV technique. The peak currents were directly proportional to the scan rate as predicted for a surface confined diffusionless system. The surface coverage ({gamma}) and the concentration of Fe(CN){sub 6}{sup 4-} were determined to be 1.88 x 10{sup -8} mol/cm{sup 2} and 0.641 mol/dm{sup 3}, respectively. By neglecting cations incorporation during redox reaction of the PBV film and also based on the results obtained from energy-dispersive X-ray spectroscopy for the films of as-deposited, reduced and oxidized states, an ion exchange mechanism was

  12. Inhibition of the MRP1-mediated transport of the menadione-glutathione conjugate (thiodione) in HeLa cells as studied by SECM.

    Science.gov (United States)

    Koley, Dipankar; Bard, Allen J

    2012-07-17

    Oxidative stress induced in live HeLa cells by menadione (2-methyl-1,4-napthaquinone) was studied in real time by scanning electrochemical microscopy (SECM). The hydrophobic molecule menadione diffuses through a living cell membrane where it is toxic to the cell. However, in the cell it is conjugated with glutathione to form thiodione. Thiodione is then recognized and transported across the cell membrane via the ATP-driven MRP1 pump. In the extracellular environment, thiodione was detected by the SECM tip at levels of 140, 70, and 35 µM upon exposure of the cells to menadione concentrations of 500, 250, and 125 µM, respectively. With the aid of finite element modeling, the kinetics of thiodione transport was determined to be 1.6 10(-7) m/s, about 10 times faster than menadione uptake. Selective inhibition of these MRP1 pumps inside live HeLa cells by MK571 produced a lower thiodione concentration of 50 µM in presence of 500 µM menadione and 50 µM MK571. A similar reduced (50% drop) thiodione efflux was observed in the presence of monoclonal antibody QCRL-4, a selective blocking agent of the MRP1 pumps. The reduced thiodione flux confirmed that thiodione was transported by MRP1, and that glutathione is an essential substrate for MRP1-mediated transport. This finding demonstrates the usefulness of SECM in quantitative studies of MRP1 inhibitors and suggests that monoclonal antibodies can be a useful tool in inhibiting the transport of these MDR pumps, and thereby aiding in overcoming multidrug resistance.

  13. Electrochemical monitoring of intracellular enzyme activity of single living mammalian cells by using a double-mediator system

    International Nuclear Information System (INIS)

    Matsumae, Yoshiharu; Takahashi, Yasufumi; Ino, Kosuke; Shiku, Hitoshi; Matsue, Tomokazu

    2014-01-01

    Graphical abstract: NAD(P)H:quinone oxidoreductase (NQO) activity of single HeLa cells were evaluated by using the menadione–ferrocyanide double mediator system combined with scanning electrochemical microscopy (SECM). - Highlights: • NAD(P)H:quinone oxidoreductase activity of single cells were evaluated with SECM. • Fe(CN) 6 3− /menadione concentrations were optimized for long-term SECM monitoring. • Menadione affect the intracellular levels of reactive oxygen species and GSH. • At 100 μM menadione, the Fe(CN) 6 3− generation rate decreased rapidly within 30 min. - Abstract: We evaluated the intracellular NAD(P)H:quinone oxidoreductase (NQO) activity of single HeLa cells by using the menadione–ferrocyanide double-mediator system combined with scanning electrochemical microscopy (SECM). The double-mediator system was used to amplify the current response from the intracellular NQO activity and to reduce menadione-induced cell damage. The electron shuttle between the electrode and menadione was mediated by the ferrocyanide/ferricyanide redox couple. Generation of ferrocyanide was observed immediately after the addition of a lower concentration (10 μM) of menadione. The ferrocyanide generation rate was constant for 120 min. At a higher menadione concentration (100 μM), the ferrocyanide generation rate decreased within 30 min because of the cytotoxic effect of menadione. We also investigated the relationship between intracellular reactive oxygen species or glutathione levels and exposure to different menadione concentrations to determine the optimal condition for SECM with minimal invasiveness. The present study clearly demonstrates that SECM is useful for the analysis of intracellular enzymatic activities in single cells with a double-mediator system

  14. Electrochemical monitoring of intracellular enzyme activity of single living mammalian cells by using a double-mediator system

    Energy Technology Data Exchange (ETDEWEB)

    Matsumae, Yoshiharu [Graduate School of Environmental Studies, Tohoku University, Aramaki 6-6-11-605, Aoba, Sendai 980-8579 (Japan); Takahashi, Yasufumi [Advanced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba, Sendai 980-8577 (Japan); Ino, Kosuke [Graduate School of Environmental Studies, Tohoku University, Aramaki 6-6-11-605, Aoba, Sendai 980-8579 (Japan); Shiku, Hitoshi, E-mail: shiku@bioinfo.che.tohoku.ac.jp [Graduate School of Environmental Studies, Tohoku University, Aramaki 6-6-11-605, Aoba, Sendai 980-8579 (Japan); Matsue, Tomokazu, E-mail: matsue@bioinfo.che.tohoku.ac.jp [Graduate School of Environmental Studies, Tohoku University, Aramaki 6-6-11-605, Aoba, Sendai 980-8579 (Japan); Advanced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba, Sendai 980-8577 (Japan)

    2014-09-09

    Graphical abstract: NAD(P)H:quinone oxidoreductase (NQO) activity of single HeLa cells were evaluated by using the menadione–ferrocyanide double mediator system combined with scanning electrochemical microscopy (SECM). - Highlights: • NAD(P)H:quinone oxidoreductase activity of single cells were evaluated with SECM. • Fe(CN){sub 6}{sup 3−}/menadione concentrations were optimized for long-term SECM monitoring. • Menadione affect the intracellular levels of reactive oxygen species and GSH. • At 100 μM menadione, the Fe(CN){sub 6}{sup 3−} generation rate decreased rapidly within 30 min. - Abstract: We evaluated the intracellular NAD(P)H:quinone oxidoreductase (NQO) activity of single HeLa cells by using the menadione–ferrocyanide double-mediator system combined with scanning electrochemical microscopy (SECM). The double-mediator system was used to amplify the current response from the intracellular NQO activity and to reduce menadione-induced cell damage. The electron shuttle between the electrode and menadione was mediated by the ferrocyanide/ferricyanide redox couple. Generation of ferrocyanide was observed immediately after the addition of a lower concentration (10 μM) of menadione. The ferrocyanide generation rate was constant for 120 min. At a higher menadione concentration (100 μM), the ferrocyanide generation rate decreased within 30 min because of the cytotoxic effect of menadione. We also investigated the relationship between intracellular reactive oxygen species or glutathione levels and exposure to different menadione concentrations to determine the optimal condition for SECM with minimal invasiveness. The present study clearly demonstrates that SECM is useful for the analysis of intracellular enzymatic activities in single cells with a double-mediator system.

  15. Quantifying Chemical and Electrochemical Reactions in Liquids by in situ Electron Microscopy

    DEFF Research Database (Denmark)

    Canepa, Silvia

    and developing a robust imaging analysis method for quantitatively understand chemical and electrochemical process during in situ liquid electron microscopy. By using two custom-made liquid cells (an electrochemical scanning electron microscopy (EC-SEM) platform and Liquid Flow S/TEM holder) beam...... of electrochemical deposition of copper (Cu) by electrochemical liquid scanning electron microscopy (EC-SEM) was done in order to direct observe the formation of dendritic structures. Finally the shape evolution from solid to hollow structures through galvanic replacement reactions were observed for different silver...

  16. Electrochemical and surface studies of some Porphines as corrosion inhibitor for J55 steel in sweet corrosion environment

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ambrish, E-mail: ambrish.16752@ipu.co.in [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University), Chengdu, Sichuan 610500 (China); Department of Chemistry, LFTS, Lovely Professional University, Phagwara, Punjab 144402 (India); Lin, Yuanhua, E-mail: yhlin28@163.com [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University), Chengdu, Sichuan 610500 (China); Ansari, K.R.; Quraishi, M.A. [Department of Applied Chemistry, Indian Institute of Technology, Banaras Hindu University, Varanasi, U.P. (India); Ebenso, Eno. E. [Department of Chemistry, School of Mathematical & Physical Sciences, North-West University(Mafikeng Campus), Private Bag X2046, Mmabatho 2735 (South Africa); Chen, Songsong; Liu, Wanying [CNPC Key Lab for Tubular Goods Engineering (Southwest Petroleum University), Chengdu, Sichuan 610500 (China)

    2015-12-30

    Graphical abstract: Corrosion inhibition of J55 steel in 3.5 wt.% NaCl solution saturated with CO2 by the three Porphines 5,10,15,20-Tetra(4-pyridyl)-21H,23H-porphine (P1), 5,10,15,20-Tetraphenyl-21H,23H-porphine (P2), 5,10,15,20-Tetrakis(4-hydroxyphenyl)-21H,23H-porphine (P3), electrochemical impedance spectroscopy (EIS), contact angle measurement, scanning electrochemical microscopy (SECM), and atomic force microscopy (AFM). - Highlights: • J55 steel protection in 3.5% NaCl solution saturated with CO2 by Porphines. • Weight loss and impedance results are in good agreement. • The adsorption of Porphines obeys the Langmuir adsorption isotherm. • Scanning electrochemical microscopy is used to discuss the insulated and conductive surface. • Examination of surface morphology by AFM. - Abstract: Corrosion inhibition of J55 steel in 3.5 wt.% NaCl solution saturated with CO{sub 2} by the three Porphines 5,10,15,20-Tetra(4-pyridyl)-21H,23H-porphine (P1), 5,10,15,20-Tetraphenyl-21H,23H-porphine (P2), 5,10,15,20-Tetrakis(4-hydroxyphenyl)-21H,23H-porphine (P3), electrochemical impedance spectroscopy (EIS), Contact angle measurement, scanning electrochemical microscopy (SECM), and atomic force microscopy (AFM). Adsorption of such Porphines on the J55 steel surface obeyed to the Langmuir adsorption isotherm. Atomic force microscopy (AFM), SECM, and Contact angle results confirm the formation of inhibitor film on J55 steel surface thereby mitigating corrosion.

  17. Electrochemical and surface studies of some Porphines as corrosion inhibitor for J55 steel in sweet corrosion environment

    International Nuclear Information System (INIS)

    Singh, Ambrish; Lin, Yuanhua; Ansari, K.R.; Quraishi, M.A.; Ebenso, Eno. E.; Chen, Songsong; Liu, Wanying

    2015-01-01

    Graphical abstract: Corrosion inhibition of J55 steel in 3.5 wt.% NaCl solution saturated with CO2 by the three Porphines 5,10,15,20-Tetra(4-pyridyl)-21H,23H-porphine (P1), 5,10,15,20-Tetraphenyl-21H,23H-porphine (P2), 5,10,15,20-Tetrakis(4-hydroxyphenyl)-21H,23H-porphine (P3), electrochemical impedance spectroscopy (EIS), contact angle measurement, scanning electrochemical microscopy (SECM), and atomic force microscopy (AFM). - Highlights: • J55 steel protection in 3.5% NaCl solution saturated with CO2 by Porphines. • Weight loss and impedance results are in good agreement. • The adsorption of Porphines obeys the Langmuir adsorption isotherm. • Scanning electrochemical microscopy is used to discuss the insulated and conductive surface. • Examination of surface morphology by AFM. - Abstract: Corrosion inhibition of J55 steel in 3.5 wt.% NaCl solution saturated with CO_2 by the three Porphines 5,10,15,20-Tetra(4-pyridyl)-21H,23H-porphine (P1), 5,10,15,20-Tetraphenyl-21H,23H-porphine (P2), 5,10,15,20-Tetrakis(4-hydroxyphenyl)-21H,23H-porphine (P3), electrochemical impedance spectroscopy (EIS), Contact angle measurement, scanning electrochemical microscopy (SECM), and atomic force microscopy (AFM). Adsorption of such Porphines on the J55 steel surface obeyed to the Langmuir adsorption isotherm. Atomic force microscopy (AFM), SECM, and Contact angle results confirm the formation of inhibitor film on J55 steel surface thereby mitigating corrosion.

  18. Intermittent contact atomic force microscopy in electrochemical environment

    Energy Technology Data Exchange (ETDEWEB)

    Haering, P; Koetz, R [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Siegenthaler, H [Bern Univ., Bern (Switzerland)

    1997-06-01

    In situ measurements with Atomic Force Microscopy may cause surface modifications due to the tip-surface interactions. As an alternative and less destructive method, Intermittent Contact Atomic Force Microscopy (ICAFM) has been tested in an electrolytic environment. In the ICAFM mode the tip is not constantly in contact with the surface under investigation but is tapping onto the surface with a certain frequency. A commercial Park Scientific Instruments Microscopy has been modified to enable in situ experiment with ICAFM. It was possible to image iridium oxide films with ICAFM in the electrolytic environment without any noticeable surface modifications. (author) 3 figs., 4 refs.

  19. Single-step electrochemical method for producing very sharp Au scanning tunneling microscopy tips

    International Nuclear Information System (INIS)

    Gingery, David; Buehlmann, Philippe

    2007-01-01

    A single-step electrochemical method for making sharp gold scanning tunneling microscopy tips is described. 3.0M NaCl in 1% perchloric acid is compared to several previously reported etchants. The addition of perchloric acid to sodium chloride solutions drastically shortens etching times and is shown by transmission electron microscopy to produce very sharp tips with a mean radius of curvature of 15 nm

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  1. Photoelectrochemical kinetics of Eosin Y-sensitized zinc oxide films investigated by scanning electrochemical microscopy under illumination with different LED

    International Nuclear Information System (INIS)

    Shen Yan; Tefashe, Ushula Mengesha; Nonomura, Kazuteru; Loewenstein, Thomas; Schlettwein, Derck; Wittstock, Gunther

    2009-01-01

    The overall efficiency of the light-induced charge separation in dye-sensitized solar cells depends on the kinetic competition between back electron transfer and dye regeneration processes by a redox electrolyte. In a previous study, the reduction of the intermittently formed photo-oxidized dye molecules by iodide ions in the electrolyte phase was investigated using the feedback mode of a scanning electrochemical microscope (SECM) and a quantitative model had been derived. Here we provide a more thorough experimental verification of this model by variation of the excitation wavelength, light intensities and mediator concentrations. Nanoporous ZnO/Eosin Y films prepared by self-assembly were used as model electrodes and were used with an iodide/triiodide electrolyte. The experimentally found effective rate constants could be related to the rate constant for the reaction of the dissolved donor with photo-oxidized Eosin Y bound to ZnO and the absorption spectrum of the dye and confirmed the assumption made in the derivation of the model. For the regeneration process of Eosin Y, a rate constant of k ox with different light emitting diodes and light intensities is determined.

  2. Photoelectrochemical kinetics of Eosin Y-sensitized zinc oxide films investigated by scanning electrochemical microscopy under illumination with different LED

    Energy Technology Data Exchange (ETDEWEB)

    Shen Yan; Tefashe, Ushula Mengesha [Department of Pure and Applied Chemistry, Faculty of Mathematics and Natural Sciences, Carl von Ossietzky University of Oldenburg, D-26111 Oldenburg (Germany); Nonomura, Kazuteru; Loewenstein, Thomas; Schlettwein, Derck [Institute of Applied Physics, Justus Liebig University of Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen (Germany); Wittstock, Gunther, E-mail: gunther.wittstock@uni-oldenburg.d [Department of Pure and Applied Chemistry, Faculty of Mathematics and Natural Sciences, Carl von Ossietzky University of Oldenburg, D-26111 Oldenburg (Germany)

    2009-12-30

    The overall efficiency of the light-induced charge separation in dye-sensitized solar cells depends on the kinetic competition between back electron transfer and dye regeneration processes by a redox electrolyte. In a previous study, the reduction of the intermittently formed photo-oxidized dye molecules by iodide ions in the electrolyte phase was investigated using the feedback mode of a scanning electrochemical microscope (SECM) and a quantitative model had been derived. Here we provide a more thorough experimental verification of this model by variation of the excitation wavelength, light intensities and mediator concentrations. Nanoporous ZnO/Eosin Y films prepared by self-assembly were used as model electrodes and were used with an iodide/triiodide electrolyte. The experimentally found effective rate constants could be related to the rate constant for the reaction of the dissolved donor with photo-oxidized Eosin Y bound to ZnO and the absorption spectrum of the dye and confirmed the assumption made in the derivation of the model. For the regeneration process of Eosin Y, a rate constant of k{sub ox} with different light emitting diodes and light intensities is determined.

  3. Scanning electrochemical microscopy determination of hydrogen flux at liquid|liquid interface with potentiometric probe

    OpenAIRE

    Jedraszko, Justyna; Nogala, Wojciech; Adamiak, Wojciech; Girault, Hubert H.; Opallo, Marcin

    2014-01-01

    Scanning electrochemical microscopy potentiometric determination of local hydrogen concentration and its flux next to the liquid|liquid interface was demonstrated. This method is based on the shift of open circuit potential of Pt-based reversible hydrogen electrode. The detection system was verified with a system generating hydrogen under galvanostatic conditions. Then, it was applied to aqueous|1,2-dichloroethane interface where hydrogen is produced with decamethylferrocene as electron donor.

  4. Multifunctional scanning ion conductance microscopy

    Science.gov (United States)

    Page, Ashley; Unwin, Patrick R.

    2017-01-01

    Scanning ion conductance microscopy (SICM) is a nanopipette-based technique that has traditionally been used to image topography or to deliver species to an interface, particularly in a biological setting. This article highlights the recent blossoming of SICM into a technique with a much greater diversity of applications and capability that can be used either standalone, with advanced control (potential–time) functions, or in tandem with other methods. SICM can be used to elucidate functional information about interfaces, such as surface charge density or electrochemical activity (ion fluxes). Using a multi-barrel probe format, SICM-related techniques can be employed to deposit nanoscale three-dimensional structures and further functionality is realized when SICM is combined with scanning electrochemical microscopy (SECM), with simultaneous measurements from a single probe opening up considerable prospects for multifunctional imaging. SICM studies are greatly enhanced by finite-element method modelling for quantitative treatment of issues such as resolution, surface charge and (tip) geometry effects. SICM is particularly applicable to the study of living systems, notably single cells, although applications extend to materials characterization and to new methods of printing and nanofabrication. A more thorough understanding of the electrochemical principles and properties of SICM provides a foundation for significant applications of SICM in electrochemistry and interfacial science. PMID:28484332

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

    International Nuclear Information System (INIS)

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

    1996-01-01

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

  6. Accessing the dynamics of end-grafted flexible polymer chains by atomic force-electrochemical microscopy. Theoretical modeling of the approach curves by the elastic bounded diffusion model and Monte Carlo simulations. Evidence for compression-induced lateral chain escape.

    Science.gov (United States)

    Abbou, Jeremy; Anne, Agnès; Demaille, Christophe

    2006-11-16

    The dynamics of a molecular layer of linear poly(ethylene glycol) (PEG) chains of molecular weight 3400, bearing at one end a ferrocene (Fc) label and thiol end-grafted at a low surface coverage onto a gold substrate, is probed using combined atomic force-electrochemical microscopy (AFM-SECM), at the scale of approximately 100 molecules. Force and current approach curves are simultaneously recorded as a force-sensing microelectrode (tip) is inserted within the approximately 10 nm thick, redox labeled, PEG chain layer. Whereas the force approach curve gives access to the structure of the compressed PEG layer, the tip-current, resulting from tip-to-substrate redox cycling of the Fc head of the chain, is controlled by chain dynamics. The elastic bounded diffusion model, which considers the motion of the Fc head as diffusion in a conformational field, complemented by Monte Carlo (MC) simulations, from which the chain conformation can be derived for any degree of confinement, allows the theoretical tip-current approach curve to be calculated. The experimental current approach curve can then be very satisfyingly reproduced by theory, down to a tip-substrate separation of approximately 2 nm, using only one adjustable parameter characterizing the chain dynamics: the effective diffusion coefficient of the chain head. At closer tip-substrate separations, an unpredicted peak is observed in the experimental current approach curve, which is shown to find its origin in a compression-induced escape of the chain from within the narrowing tip-substrate gap. MC simulations provide quantitative support for lateral chain elongation as the escape mechanism.

  7. Scanning electrochemical microscopy of menadione-glutathione conjugate export from yeast cells

    Science.gov (United States)

    Mauzeroll, Janine; Bard, Allen J.

    2004-01-01

    The uptake of menadione (2-methyl-1,4-naphthoquinone), which is toxic to yeast cells, and its expulsion as a glutathione complex were studied by scanning electrochemical microscopy. The progression of the in vitro reaction between menadione and glutathione was monitored electrochemically by cyclic voltammetry and correlated with the spectroscopic (UV–visible) behavior. By observing the scanning electrochemical microscope tip current of yeast cells suspended in a menadione-containing solution, the export of the conjugate from the cells with time could be measured. Similar experiments were performed on immobilized yeast cell aggregates stressed by a menadione solution. From the export of the menadione-glutathione conjugate detected at a 1-μm-diameter electrode situated 10 μm from the cells, a flux of about 30,000 thiodione molecules per second per cell was extracted. Numerical simulations based on an explicit finite difference method further revealed that the observation of a constant efflux of thiodione from the cells suggested the rate was limited by the uptake of menadione and that the efflux through the glutathione-conjugate pump was at least an order of magnitude faster. PMID:15148374

  8. Coating of tips for electrochemical scanning tunneling microscopy by means of silicon, magnesium, and tungsten oxides

    Science.gov (United States)

    Salerno, Marco

    2010-09-01

    Different combinations of metal tips and oxide coatings have been tested for possible operation in electrochemical scanning tunneling microscopy. Silicon and magnesium oxides have been thermally evaporated onto gold and platinum-iridium tips, respectively. Two different thickness values have been explored for both materials, namely, 40 and 120 nm for silicon oxide and 20 and 60 nm for magnesium oxide. Alternatively, tungsten oxide has been grown on tungsten tips via electrochemical anodization. In the latter case, to seek optimal results we have varied the pH of the anodizing electrolyte between one and four. The oxide coated tips have been first inspected by means of scanning electron microscopy equipped with microanalysis to determine the morphological results of the coating. Second, the coated tips have been electrically characterized ex situ for stability in time by means of cyclic voltammetry in 1 M aqueous KCl supporting electrolyte, both bare and supplemented with K3[Fe(CN)6] complex at 10 mM concentration in milliQ water as an analyte. Only the tungsten oxide coated tungsten tips have shown stable electrical behavior in the electrolyte. For these tips, the uncoated metal area has been estimated from the electrical current levels, and they have been successfully tested by imaging a gold grating in situ, which provided stable results for several hours. The successful tungsten oxide coating obtained at pH=4 has been assigned to the WO3 form.

  9. Electrochemomechanics with flexoelectricity and modelling of electrochemical strain microscopy in mixed ionic-electronic conductors

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Pengfei; Hu, Shuling; Shen, Shengping, E-mail: sshen@mail.xjtu.edu.cn [State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace, Xi' an Jiaotong University, Xi' an 710049 (China)

    2016-08-14

    Recently, a new scanning probe microscopy approach, referred to as electrochemical strain microscopy (ESM), for probing local ionic flows and electrochemical reactions in solids based on the bias-strain coupling was proposed by Morozovska et al. Then, a series of theoretical papers for analyzing the image formation and spectroscopic mechanism of ESM were published within the framework of Fermi-Dirac statistics, the Vegard law, the direct flexoelectric coupling effect, the electrostriction effect, and so on. However, most of the models in these papers are limited to the partial coupling or particular process, and numerically solved by using decoupling approximation. In this paper, to model the ESM measurement with the coupling electrical-chemical-mechanical process, the chemical Gibbs function variational principle for the thermal electrical chemical mechanical fully coupling problem is proposed. The fully coupling governing equations are derived from the variational principle. When the tip concentrates the electric field within a small volume of the material, the inhomogeneous electric field is induced. So, both direct and inverse flexoelectric effects should be taken into account. Here, the bulk defect electrochemical reactions are also taken into account, which are usually omitted in the existing works. This theory can be used to deal with coupling problems in solids, including conductors, semiconductors, and piezoelectric and non-piezoelectric dielectrics. As an application of this work, a developed initial-boundary value problem is solved numerically in a mixed ion-electronic conductor. Numerical results show that it is meaningful and necessary to consider the bulk defect chemical reaction. Besides, the chemical reaction and the flexoelectric effect have an interactive influence on each other. This work can provide theoretical basis for the ESM as well as investigating the bulk chemical reaction process in solids.

  10. Development of electrochemical reporter assay using HeLa cells transfected with vector plasmids encoding various responsive elements

    Energy Technology Data Exchange (ETDEWEB)

    Shiku, Hitoshi, E-mail: shiku@bioinfo.che.tohoku.ac.jp [Graduate School of Environmental Studies, Tohoku University, 6-6-11-604 Aramaki-Aoba, Sendai 980-8579 (Japan); Takeda, Michiaki; Murata, Tatsuya [Graduate School of Environmental Studies, Tohoku University, 6-6-11-604 Aramaki-Aoba, Sendai 980-8579 (Japan); Akiba, Uichi; Hamada, Fumio [Graduate School of Engineering and Resource Science, Akita University, 1-1 Tegata gakuen-machi, Akita 010-8502 (Japan); Matsue, Tomokazu, E-mail: matsue@bioinfo.che.tohoku.ac.jp [Graduate School of Environmental Studies, Tohoku University, 6-6-11-604 Aramaki-Aoba, Sendai 980-8579 (Japan)

    2009-04-27

    Electrochemical assay using HeLa cell lines transfected with various plasmid vectors encoding SEAP (secreted alkaline phosphatase) as the reporter has been performed by using SECM (scanning electrochemical microscopy). The plasmid vector contains different responsive elements that include GRE (glucocorticoid response elements), CRE (cAMP responsive elements), or {kappa}B (binding site for NF{kappa}B (nuclear factor kappa B)) upstream of the SEAP sequence. The transfected HeLa cells were patterned on a culture dish in a 4 x 4 array of circles of diameter 300 {mu}m by using the PDMS (poly(dimethylsiloxane)) stencil technique. The cellular array was first exposed to 100 ng mL{sup -1} dexamethasone, 10 ng mL{sup -1} forskolin, or 100 ng mL{sup -1} TNF-{alpha} (tumor necrosis factor {alpha}) after which it was further cultured in an RPMI culture medium for 6 h. After incubation, the cellular array was soaked in a measuring solution containing 4.7 mM PAPP (p-aminophenylphosphate) at pH 9.5, following which electrochemical measurements were performed immediately within 40 min. The SECM method allows parallel evaluation of different cell lines transfected with pGRE-SEAP, pCRE-SEAP, and pNF{kappa}B-SEAP patterned on the same solid support for detection of the oxidation current of PAP (p-aminophenol) flux produced from only 300 HeLa cells in each stencil pattern. The results of the SECM method were highly sensitive as compared to those obtained from the conventional CL (chemiluminescence) protocol with at least 5 x 10{sup 4} cells per well.

  11. Imaging space charge regions in Sm-doped ceria using electrochemical strain microscopy

    International Nuclear Information System (INIS)

    Chen, Qian Nataly; Li, Jiangyu; Adler, Stuart B.

    2014-01-01

    Nanocrystalline ceria exhibits a total conductivity several orders of magnitude higher than microcrystalline ceria in air at high temperature. The most widely accepted theory for this enhancement (based on fitting of conductivity data to various transport and kinetic models) is that relatively immobile positively charged defects and/or impurities accumulate at the grain boundary core, leading to a counterbalancing increase in the number of mobile electrons (small polarons) within a diffuse space charge region adjacent to each grain boundary. In an effort to validate this model, we have applied electrochemical strain microscopy to image the location and relative population of mobile electrons near grain boundaries in polycrystalline Sm-doped ceria in air at 20–200 °C. Our results show the first direct (spatially resolved) evidence that such a diffuse space charge region does exist in ceria, and is localized to both grain boundaries and the gas-exposed surface

  12. Imaging space charge regions in Sm-doped ceria using electrochemical strain microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qian Nataly; Li, Jiangyu, E-mail: jjli@uw.edu [Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States); Adler, Stuart B., E-mail: stuadler@uw.edu [Department of Chemical Engineering, University of Washington, Seattle, Washington 98195 (United States)

    2014-11-17

    Nanocrystalline ceria exhibits a total conductivity several orders of magnitude higher than microcrystalline ceria in air at high temperature. The most widely accepted theory for this enhancement (based on fitting of conductivity data to various transport and kinetic models) is that relatively immobile positively charged defects and/or impurities accumulate at the grain boundary core, leading to a counterbalancing increase in the number of mobile electrons (small polarons) within a diffuse space charge region adjacent to each grain boundary. In an effort to validate this model, we have applied electrochemical strain microscopy to image the location and relative population of mobile electrons near grain boundaries in polycrystalline Sm-doped ceria in air at 20–200 °C. Our results show the first direct (spatially resolved) evidence that such a diffuse space charge region does exist in ceria, and is localized to both grain boundaries and the gas-exposed surface.

  13. Instrumentation for in situ flow electrochemical Scanning Transmission X-ray Microscopy (STXM)

    Science.gov (United States)

    Prabu, Vinod; Obst, Martin; Hosseinkhannazer, Hooman; Reynolds, Matthew; Rosendahl, Scott; Wang, Jian; Hitchcock, Adam P.

    2018-06-01

    We report the design and performance of a 3-electrode device for real time in situ scanning transmission X-ray microscopy studies of electrochemical processes under both static (sealed, non-flow) conditions and with a continuous flow of electrolytes. The device was made using a combination of silicon microfabrication and 3D printing technologies. The performance is illustrated by results of a study of copper deposition and stripping at a gold working electrode. X-ray absorption spectromicroscopy at the Cu 2p edge was used to follow the evolution as a function of potential and time of the spatial distributions of Cu(0) and Cu(i) species electro-deposited from an aqueous solution of copper sulphate. The results are interpreted in terms of competing mechanisms for the reduction of Cu(ii).

  14. 1993-1994 Final technical report for establishing the SECME Model in the District of Columbia

    Energy Technology Data Exchange (ETDEWEB)

    Vickers, R.G.

    1995-12-31

    This is the final report for a program to establish the SECME Model in the District of Columbia. This program has seen the development of a partnership between the District of Columbia Public Schools, the University of the District of Columbia, the Department of Energy, and SECME. This partnership has demonstrated positive achievement in mathematics and science education and learning in students within the District of Columbia.

  15. 1993-1994 Final technical report for establishing the SECME Model in the District of Columbia

    International Nuclear Information System (INIS)

    Vickers, R.G.

    1995-01-01

    This is the final report for a program to establish the SECME Model in the District of Columbia. This program has seen the development of a partnership between the District of Columbia Public Schools, the University of the District of Columbia, the Department of Energy, and SECME. This partnership has demonstrated positive achievement in mathematics and science education and learning in students within the District of Columbia

  16. Multiscale electrochemical analysis of the corrosion of titanium and nitinol for implant applications

    International Nuclear Information System (INIS)

    Izquierdo, J.; González-Marrero, M.B.; Bozorg, M.; Fernández-Pérez, B.M.; Vasconcelos, H.C.; Santana, J.J.; Souto, R.M.

    2016-01-01

    Highlights: • Direct screening of differences in the surface reactivity of the passive layers formed on pure titanium and nitinol. • Distinct effect of polarization on the passive layers. • Detection of nickel soluble species released from corrosion pits. - Abstract: Surface electrochemical activity of titanium and nitinol biomaterials in naturally aerated Ringer’s physiological solution was investigated using potentiodynamic polarization and scanning electrochemical microscopy (SECM) techniques. SECM was operated in feedback and redox competition modes as a function of potential applied to the substrate. The kinetics of the electron transfer rate on both materials was characterized by mathematical modelling of the Z-approach curves monitored under feedback conditions. The rate constant values greatly depended on the characteristics of the passive layers formed over the metals under potentiostatic control. A more insulating film was found on nitinol when biased at low polarizations, resulting in smaller tip current increments during tip approach to the investigated surface under positive feedback and competition operation modes. However, at higher anodic polarizations, nitinol passive layers experience breakdown, and therefore tip current values reflect the release of metal cations from the biomaterial surface.

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

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  18. Establishing the SECME model in the District of Columbia. Quarterly report, 1 January 1994--31 March 1994

    Energy Technology Data Exchange (ETDEWEB)

    Vikers, R.G.

    1994-05-01

    During this quarter, many program activities were held to help SECME teachers and counselors implement, improve and strengthen SECME school programs in the District of Columbia. Teachers were actively engaged in enhanced instructional techniques, ideas, processes and resources to help them enrich their students` learning experience. Students are busily participating in hands-on instructional activities and preparing for the SECME competition where they are learning to excel in a competitive environment designed to help them make the most of their school experience.

  19. Carbon-Based Solid-State Calcium Ion-Selective Microelectrode and Scanning Electrochemical Microscopy: A Quantitative Study of pH-Dependent Release of Calcium Ions from Bioactive Glass.

    Science.gov (United States)

    Ummadi, Jyothir Ganesh; Downs, Corey J; Joshi, Vrushali S; Ferracane, Jack L; Koley, Dipankar

    2016-03-15

    Solid-state ion-selective electrodes are used as scanning electrochemical microscope (SECM) probes because of their inherent fast response time and ease of miniaturization. In this study, we report the development of a solid-state, low-poly(vinyl chloride), carbon-based calcium ion-selective microelectrode (Ca(2+)-ISME), 25 μm in diameter, capable of performing an amperometric approach curve and serving as a potentiometric sensor. The Ca(2+)-ISME has a broad linear response range of 5 μM to 200 mM with a near Nernstian slope of 28 mV/log[a(Ca(2+))]. The calculated detection limit for Ca(2+)-ISME is 1 μM. The selectivity coefficients of this Ca(2+)-ISME are log K(Ca(2+),A) = -5.88, -5.54, and -6.31 for Mg(2+), Na(+), and K(+), respectively. We used this new type of Ca(2+)-ISME as an SECM probe to quantitatively map the chemical microenvironment produced by a model substrate, bioactive glass (BAG). In acidic conditions (pH 4.5), BAG was found to increase the calcium ion concentration from 0.7 mM ([Ca(2+)] in artificial saliva) to 1.4 mM at 20 μm above the surface. In addition, a solid-state dual SECM pH probe was used to correlate the release of calcium ions with the change in local pH. Three-dimensional pH and calcium ion distribution mapping were also obtained by using these solid-state probes. The quantitative mapping of pH and Ca(2+) above the BAG elucidates the effectiveness of BAG in neutralizing and releasing calcium ions in acidic conditions.

  20. AFSC/ABL: Southeast Coastal Monitoring Survey (SECM)-juvenile salmon and associated epipelagic ichthyofauna in the marine waters of Southeast Alaska

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — SECM research was initiated in the spring of 1997, just prior to the onset of a strong El Nio event, and has continued annually. SECM sampling occurs around Icy...

  1. Two-step controllable electrochemical etching of tungsten scanning probe microscopy tips

    KAUST Repository

    Khan, Yasser; Al-Falih, Hisham; Ng, Tien Khee; Ooi, Boon S.; Zhang, Yaping

    2012-01-01

    Dynamic electrochemical etching technique is optimized to produce tungsten tips with controllable shape and radius of curvature of less than 10 nm. Nascent features such as dynamic electrochemical etching and reverse biasing after drop-off are utilized, and two-step dynamic electrochemical etching is introduced to produce extremely sharp tips with controllable aspect ratio. Electronic current shut-off time for conventional dc drop-off technique is reduced to ?36 ns using high speed analog electronics. Undesirable variability in tip shape, which is innate to static dc electrochemical etching, is mitigated with novel dynamic electrochemical etching. Overall, we present a facile and robust approach, whereby using a novel etchant level adjustment mechanism, 30° variability in cone angle and 1.5 mm controllability in cone length were achieved, while routinely producing ultra-sharp probes. © 2012 American Institute of Physics.

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

    International Nuclear Information System (INIS)

    Lanz, Patrick; Villevieille, Claire; Novák, Petr

    2013-01-01

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

  3. Real-time mapping of salt glands on the leaf surface of Cynodon dactylon L. using scanning electrochemical microscopy.

    Science.gov (United States)

    Parthasarathy, Meera; Pemaiah, Brindha; Natesan, Ravichandran; Padmavathy, Saralla R; Pachiappan, Jayaraman

    2015-02-01

    Salt glands are specialized organelles present in the leaf tissues of halophytes, which impart salt-tolerance capability to the plant species. These glands are usually identified only by their morphology using conventional staining procedures coupled with optical microscopy. In this work, we have employed scanning electrochemical microscopy to identify the salt glands not only by their morphology but also by their salt excretion behavior. Bermuda grass (Cynodon dactylon L.) species was chosen for the study as they are known to be salt-tolerant and contain salt glands on leaf surfaces. Scanning electrochemical microscopy performed in sodium chloride medium in the presence and absence of potassium ferrocyanide as redox mediator, reveals the identity of salt glands. More insight into the ion expulsion behavior of these glands was obtained by mapping lateral and vertical variations in ion concentrations using surface impedance measurements which indicated five times higher resistance over the salt glands compared to the surrounding tissues and bulk solution. The protocol could be used to understand the developmental processes in plants grown in different soil/water conditions in order to improve salt tolerance of food crops by genetic engineering and hence improve their agricultural productivity.

  4. Quasi-steady-state voltammetry of rapid electron transfer reactions at the macroscopic substrate of the scanning electrochemical microscope.

    Science.gov (United States)

    Nioradze, Nikoloz; Kim, Jiyeon; Amemiya, Shigeru

    2011-02-01

    We report on a novel theory and experiment for scanning electrochemical microscopy (SECM) to enable quasi-steady-state voltammetry of rapid electron transfer (ET) reactions at macroscopic substrates. With this powerful approach, the substrate potential is cycled widely across the formal potential of a redox couple while the reactant or product of a substrate reaction is amperometrically detected at the tip in the feedback or substrate generation/tip collection mode, respectively. The plot of tip current versus substrate potential features the retraceable sigmoidal shape of a quasi-steady-state voltammogram although a transient voltammogram is obtained at the macroscopic substrate. Finite element simulations reveal that a short tip-substrate distance and a reversible substrate reaction (except under the tip) are required for quasi-steady-state voltammetry. Advantageously, a pair of quasi-steady-state voltammograms is obtained by employing both operation modes to reliably determine all transport, thermodynamic, and kinetic parameters as confirmed experimentally for rapid ET reactions of ferrocenemethanol and 7,7,8,8-tetracyanoquinodimethane at a Pt substrate with ∼0.5 μm-radius Pt tips positioned at 90 nm-1 μm distances. Standard ET rate constants of ∼7 cm/s were obtained for the latter mediator as the largest determined for a substrate reaction by SECM. Various potential applications of quasi-steady-state voltammetry are also proposed.

  5. Self-consistent modelling of electrochemical strain microscopy in mixed ionic-electronic conductors: Nonlinear and dynamic regimes

    Science.gov (United States)

    Varenyk, O. V.; Silibin, M. V.; Kiselev, D. A.; Eliseev, E. A.; Kalinin, S. V.; Morozovska, A. N.

    2015-08-01

    The frequency dependent Electrochemical Strain Microscopy (ESM) response of mixed ionic-electronic conductors is analyzed within the framework of Fermi-Dirac statistics and the Vegard law, accounting for steric effects from mobile donors. The emergence of dynamic charge waves and nonlinear deformation of the surface in response to bias applied to the tip-surface junction is numerically explored. The 2D maps of the strain and concentration distributions across the mixed ionic-electronic conductor and bias-induced surface displacements are calculated. The obtained numerical results can be applied to quantify the ESM response of Li-based solid electrolytes, materials with resistive switching, and electroactive ferroelectric polymers, which are of potential interest for flexible and high-density non-volatile memory devices.

  6. Self-consistent modelling of electrochemical strain microscopy in mixed ionic-electronic conductors: Nonlinear and dynamic regimes

    Energy Technology Data Exchange (ETDEWEB)

    Varenyk, O. V.; Morozovska, A. N., E-mail: sergei2@ornl.gov, E-mail: anna.n.morozovska@gmail.com [Institute of Physics, National Academy of Sciences of Ukraine, 46, pr. Nauky, 03028 Kyiv (Ukraine); Silibin, M. V. [National Research University of Electronic Technology “MIET,” 124498 Moscow (Russian Federation); Kiselev, D. A. [National University of Science and Technology “MISiS,” 119049 Moscow, Leninskiy pr. 4 (Russian Federation); Eliseev, E. A. [Institute for Problems of Materials Science, NAS of Ukraine, Krjijanovskogo 3, 03142 Kyiv (Ukraine); Kalinin, S. V., E-mail: sergei2@ornl.gov, E-mail: anna.n.morozovska@gmail.com [The Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2015-08-21

    The frequency dependent Electrochemical Strain Microscopy (ESM) response of mixed ionic-electronic conductors is analyzed within the framework of Fermi-Dirac statistics and the Vegard law, accounting for steric effects from mobile donors. The emergence of dynamic charge waves and nonlinear deformation of the surface in response to bias applied to the tip-surface junction is numerically explored. The 2D maps of the strain and concentration distributions across the mixed ionic-electronic conductor and bias-induced surface displacements are calculated. The obtained numerical results can be applied to quantify the ESM response of Li-based solid electrolytes, materials with resistive switching, and electroactive ferroelectric polymers, which are of potential interest for flexible and high-density non-volatile memory devices.

  7. Microscopy

    Science.gov (United States)

    Patricia A. Moss; Les Groom

    2001-01-01

    Microscopy is the study and interpretation of images produced by a microscope. "Interpretation" is the keyword, because the microscope enables one to see structures that are too small or too close together to be resolved by the unaided eye. (The human eye cannot separate two points or lines that are closer together than 0.1 mm.) it is important to...

  8. Single Cell Oxygen Mapping (SCOM) by Scanning Electrochemical Microscopy Uncovers Heterogeneous Intracellular Oxygen Consumption

    OpenAIRE

    Santos, Carla Santana; Kowaltowski, Alicia J.; Bertotti, Mauro

    2017-01-01

    We developed a highly sensitive oxygen consumption scanning microscopy system using platinized platinum disc microelectrodes. The system is capable of reliably detecting single-cell respiration, responding to classical regulators of mitochondrial oxygen consumption activity as expected. Comparisons with commercial multi-cell oxygen detection systems show that the system has comparable errors (if not smaller), with the advantage of being able to monitor inter and intra-cell heterogeneity in ox...

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

    Science.gov (United States)

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

    2017-09-13

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

  10. Membrane Separated Flow Cell for Parallelized Electrochemical Impedance Spectroscopy and Confocal Laser Scanning Microscopy to Characterize Electro-Active Microorganisms

    International Nuclear Information System (INIS)

    Stöckl, Markus; Schlegel, Christin; Sydow, Anne; Holtmann, Dirk; Ulber, Roland; Mangold, Klaus-Michael

    2016-01-01

    Highlights: • Development of a membrane separated electrochemical flow cell. • Simultaneous combination of EIS and CLSM. • Monitoring of bacterial cell attachment to anode of MFC. • Cell attachment of Shewanella oneidensis is shown. - Abstract: Understanding the attachment of electro-active bacteria to electrode surfaces and their subsequent biofilm formation is one of the major challenges for the establishment of bacterial bioelectrochemial systems (BES). For a constant observation of biofilm growth, providing information on different stages of biofilm formation, continuous monitoring methods are required. In this paper a combination of two powerful analytical methods, Electrochemical Impedance Spectroscopy (EIS) and Confocal Laser Scanning Microscopy (CLSM), for biofilm monitoring is presented. A custom-built flow cell with a transparent indium tin oxide working electrode (WE) was constructed allowing monitoring of cell attachment to a working electrode simultaneously by EIS and CLSM. Cyclic Voltammetry (CV) and EIS of an iron (II)/iron (III) redox couple indicate that the flow cell is suitable for electrochemical experiments. An engineered Shewanella oneidensis MR-1 (ATCC700550) producing eGFP was used as electro-active model organism to demonstrate the practical application of the flow cell as BES to monitor cell attachment simultaneously with EIS and CLSM. Applying the flow cell as MFC (transparent working electrode poised as anode) produced a typical current curve for such a system. From the equivalent circuit used to interpret EIS data the charge transfer resistance R CT is sensitive to attachment of microorganisms. Fitted R CT was increased initially after cell inoculation and then lowered constantly with progressing experimental time. In parallel taken CLSM images show that bacteria already adhered to the WE 5 min after inoculation. A mono- respectively bilayer of electro-active cells was observed after 17 h on the WE surface. With the presented

  11. Porphyrins as Corrosion Inhibitors for N80 Steel in 3.5% NaCl Solution: Electrochemical, Quantum Chemical, QSAR and Monte Carlo Simulations Studies

    Directory of Open Access Journals (Sweden)

    Ambrish Singh

    2015-08-01

    Full Text Available The inhibition of the corrosion of N80 steel in 3.5 wt. % NaCl solution saturated with CO2 by four porphyrins, namely 5,10,15,20-tetrakis(4-hydroxyphenyl-21H,23H-porphyrin (HPTB, 5,10,15,20-tetra(4-pyridyl-21H,23H-porphyrin (T4PP, 4,4′,4″,4‴-(porphyrin-5,10,15,20-tetrayltetrakis(benzoic acid (THP and 5,10,15,20-tetraphenyl-21H,23H-porphyrin (TPP was studied using electrochemical impedance spectroscopy (EIS, potentiodynamic polarization, scanning electrochemical microscopy (SECM and scanning electron microscopy (SEM techniques. The results showed that the inhibition efficiency, η% increases with increasing concentration of the inhibitors. The EIS results revealed that the N80 steel surface with adsorbed porphyrins exhibited non-ideal capacitive behaviour with reduced charge transfer activity. Potentiodynamic polarization measurements indicated that the studied porphyrins acted as mixed type inhibitors. The SECM results confirmed the adsorption of the porphyrins on N80 steel thereby forming a relatively insulated surface. The SEM also confirmed the formation of protective films of the porphyrins on N80 steel surface thereby protecting the surface from direct acid attack. Quantum chemical calculations, quantitative structure activity relationship (QSAR were also carried out on the studied porphyrins and the results showed that the corrosion inhibition performances of the porphyrins could be related to their EHOMO, ELUMO, ω, and μ values. Monte Carlo simulation studies showed that THP has the highest adsorption energy, while T4PP has the least adsorption energy in agreement with the values of σ from quantum chemical calculations.

  12. Well-ordered structure of methylene blue monolayers on Au(111) surface: electrochemical scanning tunneling microscopy studies.

    Science.gov (United States)

    Song, Yonghai; Wang, Li

    2009-02-01

    Well-ordered structure of methylene blue (MB) monolayers on Au(111) surface has been successfully obtained by controlling the substrate potential. Electrochemical scanning tunneling microscopy (ECSTM) examined the monolayers of MB on Au(111) in 0.1 M HClO(4) and showed long-range ordered, interweaved arrays of MB with quadratic symmetry on the substrate in the potential range of double-layer charging. High-resolution ECSTM image further revealed the details of the MB monolayers structure of c(5 x 5 radical 3)rect and the flat-lying orientation of ad-molecules. The dependence of molecular organization on the substrate potential and the formation mechanism of well-ordered structure on Au(111) surface were investigated in detail. The obtained well-ordered structure at the interface between a metal and an aqueous electrolyte might possibly be used as high-density device for signal memory and templates for the advanced nanopatterning of surfaces. (c) 2008 Wiley-Liss, Inc.

  13. Time dependence of the natural passivation process on AISI 304 in an alkaline medium: Atomic force microscopy and scanning Kelvin probe force microscopy as additional tools to electrochemical impedance spectroscopy

    Science.gov (United States)

    Benaioun, N. E.; Maafa, I.; Florentin, A.; Denys, E.; Hakiki, N. E.; Moulayat, N.; Bubendorff, J. L.

    2018-04-01

    Thin surface films formed on AISI 304 samples in an alkaline solution of pH = 13 are studied by atomic force microscopy (AFM), scanning Kelvin probe force microscopy (SKPFM) and electrochemical impedance spectroscopy (EIS) as a function of immersion time. The results reveal that changes on EIS diagrams correspond to topographical modifications on the sample surface as shown by AFM. Both techniques are therefore complementary. The oxide layer is chemically homogenous as shown by SKPFM imaging and our ultra-thin passive layer is an efficient barrier against corrosion.

  14. Electrochemical characterization of pulsed layer deposited hydroxyapatite-zirconia layers on Ti-21Nb-15Ta-6Zr alloy for biomedical application

    Energy Technology Data Exchange (ETDEWEB)

    Izquierdo, Javier [Department of Chemistry, Universidad de La Laguna, P.O. Box 456, E-38200 La Laguna, Tenerife (Spain); Bolat, Georgiana [“Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, 73 Prof. Dr. Doc. D. Mangeron Street, 700050 Iasi (Romania); Cimpoesu, Nicanor [“Gheorghe Asachi” Technical University of Iasi, Faculty of Materials Science, 61-63 Prof. Dr. Doc. D. Mangeron Street, 700050 Iasi (Romania); Trinca, Lucia Carmen [Science Department, University of Agricultural Sciences and Veterinary Medicine, M. Sadoveanu Alley 3, 700490 Iasi (Romania); Mareci, Daniel, E-mail: danmareci@yahoo.com [“Gheorghe Asachi” Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, 73 Prof. Dr. Doc. D. Mangeron Street, 700050 Iasi (Romania); Souto, Ricardo Manuel, E-mail: rsouto@ull.es [Department of Chemistry, Universidad de La Laguna, P.O. Box 456, E-38200 La Laguna, Tenerife (Spain); Institute of Material Science and Nanotechnology, Universidad de La Laguna, E-38200 La Laguna, Tenerife (Spain)

    2016-11-01

    Highlights: • New quarternary Ti-based alloy for biomaterial application. • Combined hydroxyapatite-zirconia coating produced by pulsed laser deposition. • Porous layer formed on the coated alloy blocks electron transfer reactions. • Electrochemical behaviour consistent with passive film with duplex structure. • HA–ZrO{sub 2} coated Ti-21Nb-15Ta-6Zr exhibits high potential for osseointegration. - Abstract: A new titanium base Ti-21Nb-15Ta-6Zr alloy covered with hydroxyapatite-zirconia (HA–ZrO{sub 2}) by pulsed laser deposition (PLD) technique was characterized regarding its corrosion resistance in simulated physiological Ringer’s solution at 37 °C. For the sake of comparison, Ti-6Al-4V standard implant alloy, with and without hydroxyapatite-zirconia coating, was also characterized. Multiscale electrochemical analysis using both conventional averaging electrochemical techniques, namely electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization, and spatially-resolved microelectrochemical techniques (scanning electrochemical microscopy, SECM) were used to investigate the electrochemical behaviour of the materials. In addition, scanning electron microscopy evidenced that no relevant surface morphology changes occurred on the materials upon immersion in the simulated physiological solution, despite variations in their electrochemical behaviour. Although uncoated metals appear to show better performances during conventional corrosion tests, the response is still quite similar for the HA–ZrO{sub 2} coated materials while providing superior resistance towards electron transfer due to the formation of a more dense film on the surface, thus effectively behaving as a passive material. It is believed corrosion of the HA–ZrO{sub 2} coated Ti-21Nb-15Ta-6Zr alloy will have negligible effect upon biochemical and cellular events at the bone-implant interface and could facilitate osseointegration.

  15. Lipid Bilayer Membrane in a Silicon Based Micron Sized Cavity Accessed by Atomic Force Microscopy and Electrochemical Impedance Spectroscopy.

    Science.gov (United States)

    Khan, Muhammad Shuja; Dosoky, Noura Sayed; Patel, Darayas; Weimer, Jeffrey; Williams, John Dalton

    2017-07-05

    Supported lipid bilayers (SLBs) are widely used in biophysical research to probe the functionality of biological membranes and to provide diagnoses in high throughput drug screening. Formation of SLBs at below phase transition temperature ( Tm ) has applications in nano-medicine research where low temperature profiles are required. Herein, we report the successful production of SLBs at above-as well as below-the Tm of the lipids in an anisotropically etched, silicon-based micro-cavity. The Si-based cavity walls exhibit controlled temperature which assist in the quick and stable formation of lipid bilayer membranes. Fusion of large unilamellar vesicles was monitored in real time in an aqueous environment inside the Si cavity using atomic force microscopy (AFM), and the lateral organization of the lipid molecules was characterized until the formation of the SLBs. The stability of SLBs produced was also characterized by recording the electrical resistance and the capacitance using electrochemical impedance spectroscopy (EIS). Analysis was done in the frequency regime of 10 -2 -10⁵ Hz at a signal voltage of 100 mV and giga-ohm sealed impedance was obtained continuously over four days. Finally, the cantilever tip in AFM was utilized to estimate the bilayer thickness and to calculate the rupture force at the interface of the tip and the SLB. We anticipate that a silicon-based, micron-sized cavity has the potential to produce highly-stable SLBs below their Tm . The membranes inside the Si cavity could last for several days and allow robust characterization using AFM or EIS. This could be an excellent platform for nanomedicine experiments that require low operating temperatures.

  16. Electrochemical performance of potentiodynamically deposited polyaniline electrodes in ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Patil, Dipali S., E-mail: dipali.patilphy@gmail.com [Department of Physics, Yeungnam University, Gyeonbuk 712-749 (Korea, Republic of); Thin Film Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India); Pawar, S.A. [Thin Film Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India); Department of Materials Science and Engineering, Chonnam National University, Gwangju 500 757 (Korea, Republic of); Patil, S.K.; Salavi, P.P.; Kolekar, S.S. [Department of Chemistry, Shivaji University, Kolhapur 416 004 (India); Devan, R.S.; Ma, Y.R. [Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan (China); Kim, J.H. [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500 757 (Korea, Republic of); Shin, J.C. [Department of Physics, Yeungnam University, Gyeonbuk 712-749 (Korea, Republic of); Patil, P.S., E-mail: patilps_2000@yahoo.com [Thin Film Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India)

    2015-10-15

    Present work reports electropolymerization of aniline onto stainless steel substrate using room temperature ionic liquid N-methyl-2-pyrrolidonium hydrogensulfate [NMP][HSO{sub 4}] by potentiodynamic electrodeposition method. To study the effect of electropolymerization cycle number on the electrochemical performance, the number of scans is varied from 1{sup st} to 5{sup th} cycle. X-ray photoelectron spectroscopy is used for the phase identification of polyaniline (PANI) films. Scanning electrochemical microscopy (SECM) was used to study the electrochemical activity of PANI films. The highest specific capacitance of 581 Fg{sup −1} and energy density of 96.6 whkg{sup −1} are obtained for the sample, deposited using four cycle. - Graphical abstract: We have synthesized PANI samples with different thickness (or deposited mass) on stainless steel as a function of deposition cycles by potentiodynamic electrodeposition in room temperature IL [NMP][HSO{sub 4}]. A globular nanostructural growth of PANI is observed over the compact background of PANI for sample P{sub 2}. The sample P{sub 4} revealed a globular structure with spongy porous morphology. This nanostructure and porous structure is useful for supercapacitor, because it reduces the diffusion resistance of the electrolyte into electrode matrix. - Highlights: • Electropolymerization of aniline using room temperature ionic liquid N-methyl-2-pyrrolidonium hydrogensulfate [NMP][HSO4]. • The highest specific capacitance of 581 Fg{sup −1} and energy density of 96.60 Whkg{sup −1} is observed for the optimized sample. • The improved specific capacitance of PANI electrode material can be used to develop high performance supercapacitor.

  17. Electrochemical performance of potentiodynamically deposited polyaniline electrodes in ionic liquid

    International Nuclear Information System (INIS)

    Patil, Dipali S.; Pawar, S.A.; Patil, S.K.; Salavi, P.P.; Kolekar, S.S.; Devan, R.S.; Ma, Y.R.; Kim, J.H.; Shin, J.C.; Patil, P.S.

    2015-01-01

    Present work reports electropolymerization of aniline onto stainless steel substrate using room temperature ionic liquid N-methyl-2-pyrrolidonium hydrogensulfate [NMP][HSO 4 ] by potentiodynamic electrodeposition method. To study the effect of electropolymerization cycle number on the electrochemical performance, the number of scans is varied from 1 st to 5 th cycle. X-ray photoelectron spectroscopy is used for the phase identification of polyaniline (PANI) films. Scanning electrochemical microscopy (SECM) was used to study the electrochemical activity of PANI films. The highest specific capacitance of 581 Fg −1 and energy density of 96.6 whkg −1 are obtained for the sample, deposited using four cycle. - Graphical abstract: We have synthesized PANI samples with different thickness (or deposited mass) on stainless steel as a function of deposition cycles by potentiodynamic electrodeposition in room temperature IL [NMP][HSO 4 ]. A globular nanostructural growth of PANI is observed over the compact background of PANI for sample P 2 . The sample P 4 revealed a globular structure with spongy porous morphology. This nanostructure and porous structure is useful for supercapacitor, because it reduces the diffusion resistance of the electrolyte into electrode matrix. - Highlights: • Electropolymerization of aniline using room temperature ionic liquid N-methyl-2-pyrrolidonium hydrogensulfate [NMP][HSO4]. • The highest specific capacitance of 581 Fg −1 and energy density of 96.60 Whkg −1 is observed for the optimized sample. • The improved specific capacitance of PANI electrode material can be used to develop high performance supercapacitor

  18. Evolution of the Corrosion Morphology on AZ31B Tracked Electrochemically and by In Situ Microscopy in Chloride-Containing Media

    Science.gov (United States)

    Melia, M. A.; Cain, T. W.; Briglia, B. F.; Scully, J. R.; Fitz-Gerald, J. M.

    2017-11-01

    The evolution of open-circuit corrosion morphology as a function of immersion time for Mg alloy AZ31B in 0.6-M NaCl solution was investigated. Real-time optical microscopy accompanied by simultaneous electrochemical characterization was used to characterize the filiform corrosion (FFC) of AZ31B. Specifically, the behavior of propagating corrosion filaments on the metal surface was observed, and correlations among polarization resistance, filament propagation rates, open-circuit potential, and active coverage of local corrosion sites were revealed. Three distinct stages of corrosion were observed in 0.6-M NaCl. An initial passive region, during which a slow potential rise occurred (termed stage I), a second FFC region (termed stage II) with shallow penetrating, distinct filaments, and a final FFC region (termed stage III) with deeper penetrating filaments, aligned to form a linear front. The electrochemical properties of each stage are discussed, providing insights into the penetration rates and corrosion model.

  19. Electrochemical characteristics of bioresorbable binary MgCa alloys in Ringer's solution: Revealing the impact of local pH distributions during in-vitro dissolution.

    Science.gov (United States)

    Mareci, D; Bolat, G; Izquierdo, J; Crimu, C; Munteanu, C; Antoniac, I; Souto, R M

    2016-03-01

    Biodegradable magnesium-calcium (MgCa) alloy is a very attractive biomaterial. Two MgCa alloys below the solid solubility of Ca were considered, as to solely investigate the effect of Ca content on the behavior of magnesium and the pH changes associated to metal dissolution. X-ray diffraction analysis and optical microscopy showed that both Mg-0.63Ca and Mg-0.89Ca alloys were solely composed of α(Mg) phase. Degradation characteristics and electrochemical characterization of MgCa alloys were investigated during exposure to Ringer's solution at 37 °C by electrochemical impedance spectroscopy and scanning electrochemical microscopy. The impedance behavior showed both capacitive and inductive features that are related to the alloy charge transfer reaction and the relaxation of the absorbed corrosion compounds, and can be described in terms of an equivalent circuit. Scanning electron microscopy (SEM) was employed to view the surface morphology of the MgCa samples after 1 week immersion in Ringer's solution showing extensive precipitation of corrosion products, whereas the substrate shows evidence of a non-uniform corrosion process. Energy dispersive analysis showed that the precipitates contained oxygen, calcium, magnesium and chlorine, and the Mg:Ca ratios were smaller than in the alloys. Scanning electrochemical microscopy (SECM) was used to visualize local pH changes associated to these physicochemical processes with high spatial resolution. The occurrence of pH variations in excess of 3 units between anodic and cathodic half-cell reactions was monitored in situ. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  1. Chemical, electrical and electrochemical characterization of hybrid organic/inorganic polypyrrole/PW{sub 12}O{sub 40}{sup 3-} coating deposited on polyester fabrics

    Energy Technology Data Exchange (ETDEWEB)

    Molina, J.; Fernandez, J.; Rio, A.I. del; Bonastre, J. [Departamento de Ingenieria Textil y Papelera, EPS de Alcoy, Universitat Politecnica de Valencia, Plaza Ferrandiz y Carbonell s/n, 03801 Alcoy (Spain); Cases, F., E-mail: fjcases@txp.upv.es [Departamento de Ingenieria Textil y Papelera, EPS de Alcoy, Universitat Politecnica de Valencia, Plaza Ferrandiz y Carbonell s/n, 03801 Alcoy (Spain)

    2011-09-15

    A study of the stability of conducting fabrics of polyester (PES) coated with polypyrrole/PW{sub 12}O{sub 40}{sup 3-} (organic/inorganic hybrid material) in different pH solutions (1, 7, 13) has been done. Washing tests were also done in views of its possible application in electronic textiles such as antistatic clothing. X-ray photoelectron spectroscopy (XPS) studies have been done to quantify the amount of counter ion that remains in the polymer matrix and determine the doping ratio (N{sup +}/N) after the different tests. Scanning electron microscopy (SEM) was also used to observe morphological differences after the different tests. Surface resistivity changes were measured by means of electrochemical impedance spectroscopy (EIS). Scanning electrochemical microscopy (SECM) was employed to measure changes in electroactivity after the different tests. Higher pHs caused a decrease of the doping ratio (N{sup +}/N), the loss of part of the counter ions and the decrease of its conducting and electrocatalytic properties. The stability in acid media and neutral media and after the washing test was good. Only at pH 13 the loss of the counter ion was widespread and there was a decrease of its conducting and catalytic properties; although the fabrics continued acting mainly as a conducting material.

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

    Czech Academy of Sciences Publication Activity Database

    Kavan, Ladislav; Vlčková Živcová, Zuzana; Petrák, Václav; Frank, Otakar; Janda, Pavel; Tarábková, Hana; Nesladek, M.; Mortet, Vincent

    2015-01-01

    Roč. 179, OCT 2015 (2015), s. 626-636 ISSN 0013-4686 R&D Projects: GA ČR GA13-31783S Institutional support: RVO:61388955 ; RVO:68378271 Keywords : Raman spectroelectrochemistry * atomic force microscopy * boron doped diamond Subject RIV: CG - Electrochemistry Impact factor: 4.803, year: 2015

  3. Cyclodextrin inclusion complexes with thiocholesterol and their self-assembly on gold: A combined electrochemical and lateral force microscopy analysis

    International Nuclear Information System (INIS)

    Pandey, Rakesh K.; Lakshminarayanan, V.

    2014-01-01

    The present study is an attempt to understand the properties of an interesting self-assembled monolayer system composed of inclusion complexes of thiocholesterol and cyclodextrins. Cyclodextrins were used as host compound while thiocholesterol was used as the entrant molecule into the cavity of cyclodextrins. The improved electron transfer barrier property towards a redox couple indicates a sturdy inclusion complex monolayer. A very large R ct value, 64.6 kΩ·cm 2 for a redox system was obtained in the case of methyl-β-cyclodextrin and thiocholesterol inclusion complex self-assembled monolayer. A rather low value of capacitance 1.2 μF cm −2 measured in supporting electrolyte further signifies the fact that inclusion complex monolayer is quite impermeable for ionic species. In addition lateral force microscopy combined with force–distance analysis revealed the presence of an interesting mixed hydrophilic/hydrophobic surface. - Highlights: • Self-assembled monolayer of inclusion complexes on gold surface • Lateral force microscopy study of the regions of varying hydrophilicities • Could find applications in patterning surfaces to be hydrophilic/hydrophobic • Improved electron transfer barrier properties

  4. In Situ Characterization of Ni and Ni/Fe Thin Film Electrodes for Oxygen Evolution in Alkaline Media by a Raman-Coupled Scanning Electrochemical Microscope Setup.

    Science.gov (United States)

    Steimecke, Matthias; Seiffarth, Gerda; Bron, Michael

    2017-10-17

    We present a spectroelectrochemical setup, in which Raman microscopy is combined with scanning electrochemical microscopy (SECM) in order to provide both spectroscopic and electrochemical information on the very same location of an electrode at the same time. The setup is applied to a subject of high academic and practical interest, namely, the oxygen evolution reaction at Ni and Ni/Fe electrodes. It comprises a transparent substrate electrode, onto which Ni and Ni/Fe thin films are deposited. An ultramicroelectrode (UME) is placed closely above the substrate to obtain electrochemical information, while a Raman microscope probes the same sample spot from below. To obtain information on oxygen evolution activity and structural changes, increasingly positive potentials from 0.1 up to 0.7 V vs Hg|HgO|1 M KOH were applied to the Ni/Fe-electrodes in 0.1 M KOH solution. Evolved oxygen is detected by reduction at a Pt UME, allowing for the determination of onset potentials, while the substrate current, which is recorded in parallel, is due to both overlapping oxygen evolution and the oxidation of Ni(OH) 2 to NiOOH. An optimum of 15% Fe in Ni/Fe films with respect to oxygen evolution activity was determined. At the same time, the potential-dependent formation of γ-NiOOH characterized by the Raman double band at 475 and 557 cm -1 allows for the conclusion that a certain amount of disorder introduced by Fe atoms is necessary to obtain high oxygen evolution reaction (OER) activity.

  5. Molecular assembly and electro polymerization of 3,4-ethylenedioxy thiophene on Au(100) single crystal electrode using in-situ electrochemical scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Garcia, Jonyl L.; Tongol, Bernard John V.; ShuehLin Yau

    2012-01-01

    Electrochemical scanning tunneling microscopy (Ec-STM) is a powerful technique that can provide molecular-level information regarding electrode surface processes in-situ in electrolyte solvent under ambient conditions. In this study, the adsorption and electro polymerization of an industrially important conducting polymer precursor, 3,4-ethylenedioxy thiophene (EDOT), on Au (100) single crystal was probed using Ec-STM. The Au (100) single crystal electrode substrate used for this study was fabricated using the well-known Clavilier's flame melting procedure. Cyclic voltammetry (CV) was used along with Ec-STM to characterize the bare, EDOT-modified, and poly(EDOT)-modified Au (100) single crystal electrode. Time-dependent Ec-STM imaging at 0.550 V showed the formation of an EDOT self-assembled monolayer through 2-D surface dillusion. The resulting EDOT molecular assembly on Au (100) single crystal electrode was found to fit in a 4√2χ3√2 unit cell. Difference in apparent corrugation between molecular rows was attributed to different angular orientation with respect to the substrate. The electro polymerization of EDOT on Au (100) single crystal electrode was done by potentiostatic and potentiodynamic methods. Both methods suggested a solution-process mechanism for EDOT electro polymerization. (author)

  6. In Situ Scanning Tunneling Microscopy Topography Changes of Gold (111) in Aqueous Sulfuric Acid Produced by Electrochemical Surface Oxidation and Reduction and Relaxation Phenomena

    Science.gov (United States)

    Pasquale, M. A.; Nieto, F. J. Rodríguez; Arvia, A. J.

    The electrochemical formation and reduction of O-layers on gold (111) films in 1 m sulfuric acid under different potentiodynamic routines are investigated utilizing in situ scanning tunneling microscopy. The surface dynamics is interpreted considering the anodic and cathodic reaction pathways recently proposed complemented with concurrent relaxation phenomena occurring after gold (111) lattice mild disruption (one gold atom deep) and moderate disruption (several atoms deep). The dynamics of both oxidized and reduced gold topographies depends on the potentiodynamic routine utilized to form OH/O surface species. The topography resulting from a mild oxidative disruption is dominated by quasi-2D holes and hillocks of the order of 5 nm, involving about 500-600 gold atoms each, and their coalescence. A cooperative turnover process at the O-layer, in which the anion ad-layer and interfacial water play a key role, determines the oxidized surface topography. The reduction of these O-layers results in gold clusters, their features depending on the applied potential routine. A moderate oxidative disruption produces a surface topography of hillocks and holes several gold atoms high and deep, respectively. The subsequent reduction leads to a spinodal gold pattern. Concurrent coalescence appears to be the result of an Ostwald ripening that involves the surface diffusion of both gold atoms and clusters. These processes produce an increase in surface roughness and an incipient gold faceting. The dynamics of different topographies can be qualitatively explained employing the arguments from colloidal science theory. For 1.1 V ≤ E ≅ Epzc weak electrostatic repulsions favor gold atom/cluster coalescence, whereas for E < Epzc the attenuated electrostatic repulsions among gold surfaces stabilize small clusters over the substrate producing string-like patterns.

  7. Electrochemical, atomic force microscopy and infrared reflection absorption spectroscopy studies of pre-formed mussel adhesive protein films on carbon steel for corrosion protection

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fan, E-mail: fanzhang@kth.se [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Div. of Surface and Corrosion Science, Drottning Kristinas vaeg.51, SE-100 44 Stockholm (Sweden); Pan, Jinshan [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Div. of Surface and Corrosion Science, Drottning Kristinas vaeg.51, SE-100 44 Stockholm (Sweden); Claesson, Per Martin [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Div. of Surface and Corrosion Science, Drottning Kristinas vaeg.51, SE-100 44 Stockholm (Sweden); Institute for Surface Chemistry, P.O. Box 5607, SE-114 86 Stockholm (Sweden); Brinck, Tore [KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Physical Chemistry, Division of Physical Chemistry, Teknikringen 36, SE-10044 Stockholm (Sweden)

    2012-10-01

    Electrochemical measurements, in situ and ex situ atomic force microscopy (AFM) experiments and infrared reflection absorption spectroscopy (IRAS) analysis were performed to investigate the formation and stability as well as corrosion protection properties of mussel adhesive protein (Mefp-1) films on carbon steel, and the influence of cross-linking by NaIO{sub 4} oxidation. The in situ AFM measurements show flake-like adsorbed protein aggregates in the film formed at pH 9. The ex situ AFM images indicate multilayer-like films and that the film becomes more compact and stable in NaCl solution after the cross-linking. The IRAS results reveal the absorption bands of Mefp-1 on carbon steel before and after NaIO{sub 4} induced oxidation of the pre-adsorbed protein. Within a short exposure time, a certain corrosion protection effect was noted for the pre-formed Mefp-1 film in 0.1 M NaCl solution. Cross-linking the pre-adsorbed film by NaIO{sub 4} oxidation significantly enhanced the protection efficiency by up to 80%. - Highlights: Black-Right-Pointing-Pointer Mussel protein was tested as 'green' corrosion protection strategy for steel. Black-Right-Pointing-Pointer At pH 9, the protein adsorbs on carbon steel and forms a multilayer-like film. Black-Right-Pointing-Pointer NaIO{sub 4} leads to structural changes and cross-linking of the protein film. Black-Right-Pointing-Pointer Cross-linking results in a dense and compact film with increased stability. Black-Right-Pointing-Pointer Cross-linking of preformed film significantly enhances the corrosion protection.

  8. Electrochemical characteristics of bioresorbable binary MgCa alloys in Ringer's solution: Revealing the impact of local pH distributions during in-vitro dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Mareci, D., E-mail: danmareci@yahoo.com [Faculty of Chemical Engineering and Environmental Protection, The “Gheorghe Asachi” Technical University of Iasi, 700050, Iasi (Romania); Bolat, G. [Faculty of Chemical Engineering and Environmental Protection, The “Gheorghe Asachi” Technical University of Iasi, 700050, Iasi (Romania); Izquierdo, J. [Department of Chemistry, University of La Laguna, P.O. Box 456, E-38200 La Laguna (Tenerife) (Spain); Crimu, C.; Munteanu, C. [Faculty of Mechanical Engineering, The “Gheorghe Asachi” Technical University of Iasi, 700050, Iasi (Romania); Antoniac, I. [Faculty of Materials Science and Engineering, Politehnica of Bucharest, 060042 Bucharest (Romania); Souto, R.M., E-mail: rsouto@ull.es [Department of Chemistry, University of La Laguna, P.O. Box 456, E-38200 La Laguna (Tenerife) (Spain); Faculty of Materials Science and Engineering, Politehnica of Bucharest, 060042 Bucharest (Romania)

    2016-03-01

    Biodegradable magnesium–calcium (MgCa) alloy is a very attractive biomaterial. Two MgCa alloys below the solid solubility of Ca were considered, as to solely investigate the effect of Ca content on the behavior of magnesium and the pH changes associated to metal dissolution. X-ray diffraction analysis and optical microscopy showed that both Mg–0.63Ca and Mg–0.89Ca alloys were solely composed of α(Mg) phase. Degradation characteristics and electrochemical characterization of MgCa alloys were investigated during exposure to Ringer's solution at 37 °C by electrochemical impedance spectroscopy and scanning electrochemical microscopy. The impedance behavior showed both capacitive and inductive features that are related to the alloy charge transfer reaction and the relaxation of the absorbed corrosion compounds, and can be described in terms of an equivalent circuit. Scanning electron microscopy (SEM) was employed to view the surface morphology of the MgCa samples after 1 week immersion in Ringer's solution showing extensive precipitation of corrosion products, whereas the substrate shows evidence of a non-uniform corrosion process. Energy dispersive analysis showed that the precipitates contained oxygen, calcium, magnesium and chlorine, and the Mg:Ca ratios were smaller than in the alloys. Scanning electrochemical microscopy (SECM) was used to visualize local pH changes associated to these physicochemical processes with high spatial resolution. The occurrence of pH variations in excess of 3 units between anodic and cathodic half-cell reactions was monitored in situ. - Highlights: • Spontaneous degradation of MgCa alloys in Ringer's solution characterized at 37 °C • Reactivity differences between Mg0.63Ca and Mg0.89Ca are evidenced using multiscale electrochemical characterization. • Electrochemical activation occurs heterogeneously on the alloy surface. • Metal dissolution is accompanied by local pH changes. • Mg0.63Ca degrades faster

  9. Scanning Kelvin probe force microscopy as a means of predicting the electrochemical characteristics of the surface of a modified AA4xxx/AA3xxx (Al alloys) brazing sheet

    International Nuclear Information System (INIS)

    Afshar, F. Norouzi; Wit, J.H.W. de; Terryn, H.; Mol, J.M.C.

    2013-01-01

    Highlights: ► Macro- and micro-electrochemical surface properties of an aluminium brazing sheet were investigated. ► Electrochemical surface properties before and after brazing were studied and compared. ► Scanning Kelvin probe force microscopy and potentiodynamic polarization measurements were performed. ► The electrochemical responses were correlated to the pre- and post-brazing treatment microstructure. -- Abstract: Macro- and micro-electrochemical properties of clad and core surfaces of a modified AA4xxx/AA3xxx brazing sheet material, before and after brazing, have been evaluated and compared. By scanning Kelvin probe force microscopy (SKPFM), the Volta potential distribution over the brazed and non-brazed clad surfaces was measured. The changes in the Volta potential maps were correlated to the macro-electrochemical responses of the surfaces and the microstructural features that evolve as a result of brazing. By performing potentiodynamic polarization experiments and microscopic analysis of the corroded surfaces and cross sections, the suitability of SKPFM analysis for corrosion performance prediction of the aluminium brazing sheet material in a sea water acidified accelerated test (SWAAT) environment was confirmed. Considering the purity of Si phase in the structures of both brazed and non-brazed material, it is suggested that Si can be applied as a reliable local reference in both structures to compare the changes in Volta potential differences as the result of different heat treatments of aluminium brazing sheet. Increasing the copper content of the re-solidified clad material as a result of brazing treatment was found to increase the Volta potential of the matrix which in turn reduces the cathodic protection power of the re-solidified clad material towards the core material

  10. Optimization of Electrical Methods for Sub -surface Monitoring of Biological Contamination: From Micro-scale to Macroscopic one through Sub-micrometric Topographic and Electrochemical Studies of Oxydation/Reduction Processes Provoked by Bacteria

    Science.gov (United States)

    Dhahri, S.; Marliere, C.

    2012-12-01

    The presence of biological matter (bacteria) in deep geological sites for storage of, for instance, radioactive elements or groundwater in aquifers was clearly proved. That biomass triggers physical and chemical processes which greatly modify the durability and the sustainability of the storage sites. These processes, mainly from oxidative/reductive reactions, are poorly understood. This is mainly due to the fact that former studies were done at the macroscopic level far away from the micrometric scale where relevant processes induced by bacteria take place. Investigations at microscopic level are needed. Thus, we developed an experimental set -up based on the combined use of optical microscopy (epifluorescence and transmission), atomic force microscopy (AFM) and scanning electro -chemical microscopy (SECM) in order to get simultaneous information on topographic and electro -chemical processes at different length scales. The first highly sensitive step was to use AFM and optical microscopy with biological samples in liquid environment: We will present a new, non -perturbative method for imaging bacteria in their natural liquid environment using AFM. No immobilization protocol, neither chemical nor mechanical, is needed, contrary to what has been regarded till now as essential. Furthermore we were able to follow the natural gliding movements of bacteria, directly proving their living state during the AFM investigation: we thus directly prove the low impact of these breakthrough AFM observations on the native behavior of the bacteria. The second delicate step was to combine AFM and optical measurements with electrical ones. We mounted a new experimental set-up coupling real -time (i) monitoring of optical properties as the optical density (OD) evolution related to bulk bacterial growth in liquid or as the counting of number of bacteria adhering on the surface of the sample as well and (ii) electrical and electrochemical measurements. We thus will present results on

  11. Electrochemical study of bio-corrosion mechanisms at the carbon steel interface in presence of iron-reducing and hydrogenotrophic bacteria in the nuclear waste disposal context

    International Nuclear Information System (INIS)

    Leite-de-Souza-Moreira, Rebeca

    2013-01-01

    The safety of deep geological repository for nuclear waste is a very important and topical matter especially for the nuclear industry. Such as nuclear fuel the high level waste have to be stored for time frames of millions of years in metallic containers. Typically these containers should be placed in deep geological clay formations 500 metres underground. Corrosion processes, will take place after the re-saturation of the geological medium and under the prevalent anoxic conditions may lead to the generation of hydrogen. This gas accumulates in clay environment through the years and eventually becomes hazardous for steel containers. In the particular environment of geological repositories does not provide much biodegradable substances. This is the reason that hydrogen represents a new suitable energy source for hydrogenotrophic bacteria. Thereby formed bacterial bio-films on the containers may contribute to a process of fast decay of the steel, the so called bio-corrosion. The aim of this study is to characterize the electrochemical interfaces in order to obtain the mechanisms of bio-corrosion of carbon steels in presence of iron reducing and hydrogenotrophic bacterium Shewanella oneideinsis. The products of corrosion processes, namely hydrogen and iron (III) oxides are used as electron donor and acceptor, respectively. The amount of hydrogen consumed by Shewanella could be estimated with 10"-"4 mol s"-"1 using Scanning Electrochemical Microscopy (SECM) techniques. The influence of the local hydrogen generation was evaluated via chrono-amperometry. When hydrogen was locally generated above a carbon steel substrate an accelerated corrosion process can be observed. Eventually, using Local Electrochemical Impedance Spectroscopy (LEIS) techniques, the mechanism of the generalised corrosion process was demonstrated. (author)

  12. Graphenated tantalum(IV) oxide and poly(4-styrene sulphonic acid)-doped polyaniline nanocomposite as cathode material in an electrochemical capacitor

    International Nuclear Information System (INIS)

    Njomo, Njagi; Waryo, Tesfaye; Masikini, Milua; Ikpo, Chinwe O.; Mailu, Stephen; Tovide, Oluwakemi; Ross, Natasha; Williams, Avril; Matinise, Nolubabalo; Sunday, Christopher E.; Mayedwa, Noluthando; Baker, Priscilla G.L.; Ozoemena, Kenneth I.; Iwuoha, Emmanuel I.

    2014-01-01

    Nanostructured poly(4-styrene sulphonic acid) and tantalum (IV) oxide-doped polyaniline nanocomposite were synthesised and their electro-conductive properties were determined. The oxide was synthesized using a modified sol-gel method and then dispersed in acidic media through sonication and entrapped in-situ into the polymeric matrix during the oxidative chemical polymerization of aniline doped with poly(4-styrene sulphonic acid). The oxides and novel polymeric nanocomposite were characterised with TEM, SEM, EDX, XRD, FTIR, UV-visible to ascertain elemental and phase composition, successful polymerization, doping, morphology and entrapment of the metal oxide nanoparticles. The electro-conductivity of the nanomaterial was interrogated using scanning electrochemical microscopy (SECM) and cyclic voltammetry (CV). The material was then anchored on activated graphitic carbon and used in the design of an asymmetric supercapacitor cell using 6 M KOH aqueous electrolyte. Characteristically high specific capacitance values of 318.4 F/g with a corresponding energy and power densities of 1.57 kWh/kg and 0.435 kW/kg, respectively, were demonstrated. The cell also showed high coulombic efficiency of 94.9% with a long cycle life and good cycle stability making the nanomaterial suitable for constructing supercapacitor cell electrodes

  13. The study of optimal conditions of electrochemical etching of tunnel electron microscopy tungsten tips; Estudio de las condiciones optimas para la preparacion electroquimica de puntas de tungsteno para el Microscopio de Efecto Tunel

    Energy Technology Data Exchange (ETDEWEB)

    Anguiano, E; Aguilar, M [Instituto de Ciencia de Materiales del SCIC, Madrid (Spain); Olivar, A I [Centro de Investigacion y de Estudios Avanzados del IPN Unidad Merida. Departamento de fisica Aplicada, Yucatan, Mexico (Mexico)

    1997-12-31

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

  14. The electrochemical interface of Ag(111) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid—A combined in-situ scanning probe microscopy and impedance study

    International Nuclear Information System (INIS)

    Li, Mian-Gang; Chen, Li; Zhong, Yun-Xin; Chen, Zhao-Bin; Yan, Jia-Wei; Mao, Bing-Wei

    2016-01-01

    The electrochemical interface between Ag(111) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) has been investigated by in-situ scanning probe microscopy (SPM) and electrochemical impedance spectroscopy (EIS). In-situ scanning tunneling microscopy (STM) characterization has revealed that there is neither surface reconstruction nor strong adsorption of EMITFSI on Ag(111) surface so that EIS investigation can be fulfilled under well-defined surface condition and in the absence of pseudo capacitive process. In-situ atom force microscopy (AFM) force curve measurements further disclose that there exists five layered structures near and normal to the surface, among them three layered structures being charged and forming the electric double layer (EDL) of the interface. An electric equivalent circuit is proposed, which comprises two serial parallel branches involving the innermost layered structure and the next two layered structures in the EDL, respectively. The inner layer circuit is given by a constant phase element (CPE) in parallel to a resistor, while the outer layer circuit is given by a capacity in parallel with a resistor-Warburg element branch. Slow response is observed for the inner layer, which is attributed to the hindrance of reorientation and/or redistribution of ions in the more ordered and robust inner layer region. The inner layer capacitance and outer layer capacitance have opposing potential dependence, and the resultant double layer capacitance shows weak potential dependence.

  15. Electrochemical attosyringe.

    Science.gov (United States)

    Laforge, François O; Carpino, James; Rotenberg, Susan A; Mirkin, Michael V

    2007-07-17

    The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In cell biology, it is often necessary to inject material of high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable to such molecules. All techniques currently used for microinjection are plagued by two common problems: the relatively large injector size and volume of injected fluid, and poor control of the amount of injected material. Here we demonstrate the possibility of electrochemical control of the fluid motion that allows one to sample and dispense attoliter-to-picoliter (10(-18) to 10(-12) liter) volumes of either aqueous or nonaqueous solutions. By changing the voltage applied across the liquid/liquid interface, one can produce a sufficient force to draw solution inside a nanopipette and then inject it into an immobilized biological cell. A high success rate was achieved in injections of fluorescent dyes into cultured human breast cells. The injection of femtoliter-range volumes can be monitored by video microscopy, and current/resistance-based approaches can be used to control injections from very small pipettes. Other potential applications of the electrochemical syringe include fluid dispensing in nanolithography and pumping in microfluidic systems.

  16. Microstructure influence on corrosion behavior of a Fe–Cr–V–N tool alloy studied by SEM/EDS, scanning Kelvin force microscopy and electrochemical measurement

    International Nuclear Information System (INIS)

    Sababi, Majid; Ejnermark, Sebastian; Andersson, Jörgen; Claesson, Per M.; Pan, Jinshan

    2013-01-01

    Highlights: ► Localized corrosion of a new N-based tool alloy (Fe–Cr–V–N) has been studied. ► One-pass mode of scanning Kelvin force microscopy (KFM) was used in the study. ► The focus was on correlation between microstructure and localized corrosion. - Abstract: Microstructure influence on corrosion behavior of an N-based tool alloy (Fe–Cr–V–N) has been studied. Electron microscopy analysis showed two types of hard phases in the alloy. One-pass mode scanning Kelvin force microscopy (KFM) was used to investigate relative nobility of the hard phases. Volta potential mapping indicates higher nobility for the hard phases than the alloy matrix, and, the V- and N-rich particles exhibit the highest Volta potential. Post-polarization analysis by SEM revealed localized dissolution initiated in matrix regions adjacent to hard phase particles, and the boundary region surrounding the Cr- and Mo-rich particles is more prone to localized corrosion.

  17. Development of novel tungsten processing technologies for electro-chemical machining (ECM) of plasma facing components

    International Nuclear Information System (INIS)

    Holstein, Nils; Krauss, Wolfgang; Konys, Juergen

    2011-01-01

    Plasma facing components for fusion applications must exhibit long-term stability under extreme conditions, and therefore material imperfections cannot be tolerated due to a high risk of technical failures. To prevent or abolish defects in refractory metals components during the manufacturing process, some methods of electro-chemical machining as S-ECM and C-ECM were developed, enabling both the processing of smooth plain defect-free surfaces of different geometry and the removal of bulk material for the shaping of three-dimensional structures, also without cracks. It is discussed, that tungsten ablation with accurate electro-chemical molding is very sensitive to the kind of electric current, and therefore current investigations focused also on the effects of frequency profiles on the sharpness of edge rounding.

  18. Confocal Raman Microscopy for the Determination of Protein and Quaternary Ammonium Ion Loadings in Biocatalytic Membranes for Electrochemical Energy Conversion and Storage

    International Nuclear Information System (INIS)

    Cai, Rong; Abdellaoui, Sofiene; Kitt, Jay P.; Irvine, Cullen; Harris, Joel M.

    2017-01-01

    Here, the need to immobilize active enzyme, while ensuring high rates of substrate turnover and electronic charge transfer with an electrode, is a centrally important challenge in the field of bioelectrocatalysis. In this work, we demonstrate the use of confocal Raman microscopy as a tool for quantitation and molecular-scale structural characterization of ionomers and proteins within biocatalytic membranes to aid in the development of energy efficient biofuel cells. A set of recently available short side chain Aquivion ionomers spanning a range of equivalent weight (EW) suitable for enzyme immobilization was investigated. Aquivion ionomers (790 EW, 830 EW and 980 EW) received in the proton-exchanged (SO 3 H) form were treated with tetra-n-butylammonium bromide (TBAB) to neutralize the ionomer and expand the size of ionic domains for enzyme incorporation. Through the use of confocal Raman microscopy, membrane TBA+ ion content was predicted in calibration studies to within a few percent of the conventional titrimetric method across the full range of TBA + : SO 3 - ratios of practical interest (0.1 to 1.7). Protein incorporation into membranes was quantified at the levels expected in biofuel cell electrodes. Furthermore, features associated with the catalytically active, enzyme-coordinated copper center were evident between 400 cm -1 - 500 cm -1 in spectra of laccase catalytic membranes, demonstrating the potential to interrogate mechanistic chemistry at the enzyme active site of biocathodes under fuel cell reaction conditions. When benchmarked against the 1100 EW Nafion ionomer in glucose/air enzymatic fuel cells (EFCs), EFCs with laccase air-breathing cathodes prepared from TBA + modified Aquivion ionomers were able to reach maximum power densities (P max ) up to 1.5 times higher than EFCs constructed with cathodes prepared from TBA + modified Nafion. The improved performance of EFCs containing the short side chain Aquivion ionomers relative to Nafion is traced to

  19. Surface monitoring for pitting evolution into uniform corrosion on Cu-Ni-Zn ternary alloy in alkaline chloride solution: ex-situ LCM and in-situ SECM

    Science.gov (United States)

    Kong, Decheng; Dong, Chaofang; Zheng, Zhaoran; Mao, Feixiong; Xu, Aoni; Ni, Xiaoqing; Man, Cheng; Yao, Jizheng; Xiao, Kui; Li, Xiaogang

    2018-05-01

    The evolution of the corrosion process on Cu-Ni-Zn alloy in alkaline chloride solution was investigated by in-situ scanning electrochemical microscopy, X-ray photoelectron spectroscopy, and ex-situ laser confocal microscopy, and the effects of ambient temperature and polarization time were also discussed. The results demonstrated a higher pitting nucleation rate and lower pit growth rate at low temperature. The ratio of pit depth to mouth diameter decreased with increasing pit volume and temperature, indicating that pits preferentially propagate in the horizontal direction rather than the vertical direction owing to the presence of corrosion products and deposited copper. The surface current was uniform and stabilized at approximately 2.2 nA during the passive stage, whereas the current increased after the pits were formed with the maximum approaching 3 nA. Increasing the temperature led to an increase in porous corrosion products (CuO, Zn(OH)2, and Ni(OH)2) and significantly increased the rate of transition from pitting to uniform corrosion. Dezincification corrosion was detected by energy dispersive spectrometry, and a mechanism for pitting transition into uniform corrosion induced by dezincification at the grain boundaries is proposed.

  20. Electrochemical reduction of graphited materials in LiClO{sub 4}-EC and LiClO{sub 4}-PC media: characterization of interface products by transmission electron microscopy; Reduction electrochimique de materiaux graphites en milieux LiCIO{sub 4}-EC et LiCIO{sub 4}-PC: caracterisation des produits d`interface par microscopie electronique a transmission

    Energy Technology Data Exchange (ETDEWEB)

    Billaud, D.; Naji, A.; Ghanbaja, J. [Universite Henri Poincare Nancy, 54 - Vandoeuvre-les-Nancy (France); Willmann, P. [Centre National d`Etudes Spatiales (CNES), 31 - Toulouse (France)

    1996-12-31

    The electrochemical intercalation of non-solvated lithium in different graphited materials has been performed in LiClO{sub 4}-ethylene carbonate (EC) medium. The irreversible capacity observed during the first output is mainly due to the formation of a passivation layer made of electrolyte reduction products. These products have been characterized for different electrode reduction potentials using transmission electron microscopy (image, diffraction) and electron energy loss spectroscopy (EELS). EC reduction on the electrode surface in presence of LiClO{sub 4} leads to the formation of Li{sub 2}CO{sub 3} for potentials close to 0.8 V vs Li{sup +}/Li. For lower potentials, the electrolyte reduction reaction goes on with the formation of different lithium alkyl-carbonates. In LiClO{sub 4}-propylene carbonate (PC) medium, the interface phenomena are different. The reduction of a graphite electrode is characterized by the exfoliation phenomenon which hinders lithium intercalation. On the contrary, the formation of the passivation layer by graphite reduction in LiClO{sub 4}-EC medium allows the cycling of the electrode in the LiClO{sub 4}-PC electrolyte. In this case, the irreversible capacity observed during the first output depends on the experimental conditions of formation of the passivation layer. Abstract only. (J.S.)

  1. Electrochemical reduction of graphited materials in LiClO{sub 4}-EC and LiClO{sub 4}-PC media: characterization of interface products by transmission electron microscopy; Reduction electrochimique de materiaux graphites en milieux LiCIO{sub 4}-EC et LiCIO{sub 4}-PC: caracterisation des produits d`interface par microscopie electronique a transmission

    Energy Technology Data Exchange (ETDEWEB)

    Billaud, D; Naji, A; Ghanbaja, J [Universite Henri Poincare Nancy, 54 - Vandoeuvre-les-Nancy (France); Willmann, P [Centre National d` Etudes Spatiales (CNES), 31 - Toulouse (France)

    1997-12-31

    The electrochemical intercalation of non-solvated lithium in different graphited materials has been performed in LiClO{sub 4}-ethylene carbonate (EC) medium. The irreversible capacity observed during the first output is mainly due to the formation of a passivation layer made of electrolyte reduction products. These products have been characterized for different electrode reduction potentials using transmission electron microscopy (image, diffraction) and electron energy loss spectroscopy (EELS). EC reduction on the electrode surface in presence of LiClO{sub 4} leads to the formation of Li{sub 2}CO{sub 3} for potentials close to 0.8 V vs Li{sup +}/Li. For lower potentials, the electrolyte reduction reaction goes on with the formation of different lithium alkyl-carbonates. In LiClO{sub 4}-propylene carbonate (PC) medium, the interface phenomena are different. The reduction of a graphite electrode is characterized by the exfoliation phenomenon which hinders lithium intercalation. On the contrary, the formation of the passivation layer by graphite reduction in LiClO{sub 4}-EC medium allows the cycling of the electrode in the LiClO{sub 4}-PC electrolyte. In this case, the irreversible capacity observed during the first output depends on the experimental conditions of formation of the passivation layer. Abstract only. (J.S.)

  2. Electrochemical biosensors

    CERN Document Server

    Cosnier, Serge

    2015-01-01

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

  3. Electrochemical Processes

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers

    1997-01-01

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

  4. Electrochemical analysis

    International Nuclear Information System (INIS)

    Hwang, Hun

    2007-02-01

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

  5. Fluorescence microscopy.

    Science.gov (United States)

    Sanderson, Michael J; Smith, Ian; Parker, Ian; Bootman, Martin D

    2014-10-01

    Fluorescence microscopy is a major tool with which to monitor cell physiology. Although the concepts of fluorescence and its optical separation using filters remain similar, microscope design varies with the aim of increasing image contrast and spatial resolution. The basics of wide-field microscopy are outlined to emphasize the selection, advantages, and correct use of laser scanning confocal microscopy, two-photon microscopy, scanning disk confocal microscopy, total internal reflection, and super-resolution microscopy. In addition, the principles of how these microscopes form images are reviewed to appreciate their capabilities, limitations, and constraints for operation. © 2014 Cold Spring Harbor Laboratory Press.

  6. Electrochemical capacitor

    Science.gov (United States)

    Anderson, Marc A.; Liu, Kuo -Chuan; Mohr, Charles M.

    1999-10-05

    An inexpensive porous metal oxide material having high surface area, good conductivity and high specific capacitance is advantageously used in an electrochemical capacitor. The materials are formed in a sol-gel process which affords control over the properties of the resultant metal oxide materials.

  7. Electrochemical construction

    Science.gov (United States)

    Einstein, Harry; Grimes, Patrick G.

    1983-08-23

    An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.

  8. Electrochemical device

    Science.gov (United States)

    Grimes, Patrick G.; Einstein, Harry; Bellows, Richard J.

    1988-01-12

    A tunnel protected electrochemical device features channels fluidically communicating between manifold, tunnels and cells. The channels are designed to provide the most efficient use of auxiliary power. The channels have a greater hydraulic pressure drop and electrical resistance than the manifold. This will provide a design with the optimum auxiliary energy requirements.

  9. Electrochemical Cell

    DEFF Research Database (Denmark)

    1999-01-01

    The invention relates to a rechargeable electrochemical cell comprising a negative electrode, an electrolyte and a positive electrode in which the positive electrode structure comprises a lithium cobalt manganese oxide of the composition Li¿2?Co¿y?Mn¿2-y?O¿4? where 0 ... for capacity losses in lithium ion cells and lithium-alloy cells....

  10. Electrochemical Design of Optical Nanoantennas

    Directory of Open Access Journals (Sweden)

    Vasilchenko V.E.

    2015-01-01

    Full Text Available Electrochemical techniques for fabricating tapered gold nanoantennas (tips are discussed. In the paper, the tunable design of nanoantennas is demonstrated. Tip parameters such as a tip apex curvature, mesoscopic morphology, aspect ratio and enhancement factor can be varied with etching electrolyte and applied voltage. The low-cost method makes tipehnahced optical spectroscopy and microscopy feasible for routine optical measurements beyond the diffraction limit.

  11. Electrochemical cell

    Science.gov (United States)

    Kaun, T.D.

    An improved secondary electrochemical cell is disclosed having a negative electrode of lithium aluminum, a positive electrode of iron sulfide, a molten electrolyte of lithium chloride and potassium chloride, and the combination that the fully charged theoretical capacity of the negative electrode is in the range of 0.5 to 1.0 that of the positive electrode. The cell thus is negative electrode limiting during discharge cycling. Preferably, the negative electrode contains therein, in the approximate range of 1 to 10 volume % of the electrode, an additive from the materials of graphitized carbon, aluminum-iron alloy, and/or magnesium oxide.

  12. Electrochemical stability of subnanometer Pt clusters

    DEFF Research Database (Denmark)

    Quinson, Jonathan; Röefzaad, Melanie; Deiana, Davide

    2018-01-01

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

  13. Electrochemical impedance spectroscopy of oxidized porous silicon

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-04-01

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

  14. Characterization of electro-oxidation catalysts using scanning electrochemical and mass spectral methods

    Science.gov (United States)

    Jambunathan, Krishnakumar

    Low temperature fuel cells have many potential benefits, including high efficiency, high energy density and environmental friendliness. However, logistically appealing fuels for this system, such as reformed hydrocarbons or alcohols, exhibit poor performance because of catalyst poisoning that occurs during oxidation at the anode. This research focuses on the analysis of several model fuels and catalyst materials to understand the impact of catalyst poisoning on reactivity. Two novel experimental tools were developed based upon the local measurement of catalyst performance using scanning, reactivity mapping probes. The Scanning Electrochemical Microscope (SECM) was used to directly measure the rate constant for hydrogen oxidation in the presence and absence of dissolved CO. The Scanning Differential Electrochemical Mass Spectrometer (SDEMS) was exploited to measure the partial and complete oxidation products of methanol and ethanol oxidation. The reactivity of Pt and Pt/Ru catalysts towards the hydrogen oxidation reaction in the absence and presence of adsorbed CO was elucidated using the SECM. Steady state rate constant measurements in the absence of CO showed that the rate of hydrogen oxidation reaction exceeded 1 cms-1 . Steady state rate constant measurements in the presence of CO indicated that the platinum surface is completely inactive due to adsorbed CO. Addition of as little as 6% Ru to the Pt electrode was found to significantly improve the activity of the electrode towards CO removal. SDEMS was used to study the electro-oxidation of methanol on Pt xRuy electrodes at different electrode potentials and temperatures. Screening measurements performed with the SDEMS showed that PtxRu y electrodes containing 6--40% Ru had the highest activity for methanol oxidation. Current efficiencies for CO2 were also calculated under different conditions. SDEMS was also used to study the electro-oxidation of ethanol on Pt xRuy electrodes. The reaction was found to occur

  15. Electrochemical energy generation

    International Nuclear Information System (INIS)

    Kreysa, G.; Juettner, K.

    1993-01-01

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

  16. Electrochemical properties of double wall carbon nanotube electrodes

    OpenAIRE

    Pumera, Martin

    2007-01-01

    AbstractElectrochemical properties of double wall carbon nanotubes (DWNT) were assessed and compared to their single wall (SWNT) counterparts. The double and single wall carbon nanotube materials were characterized by Raman spectroscopy, scanning and transmission electron microscopy and electrochemistry. The electrochemical behavior of DWNT film electrodes was characterized by using cyclic voltammetry of ferricyanide and NADH. It is shown that while both DWNT and SWNT were significantly funct...

  17. Chemical Production of Graphene Catalysts for Electrochemical Energy Conversion

    DEFF Research Database (Denmark)

    Seselj, Nedjeljko

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

  18. Electrochemical behaviour of monolayer and bilayer graphene

    OpenAIRE

    Valota, Anna T.; Kinloch, Ian A.; Novoselov, Kostya S.; Casiraghi, Cinzia; Eckmann, Axel; Hill, Ernie W.; Dryfe, Robert A. W.

    2011-01-01

    Results of a study on the electrochemical properties of exfoliated single and multilayer graphene flakes are presented. Graphene flakes were deposited on silicon/silicon oxide wafers to enable fast and accurate characterization by optical microscopy and Raman spectroscopy. Conductive silver paint and silver wires were used to fabricate contacts; epoxy resin was employed as masking coating in order to expose a stable, well defined area of graphene. Both multilayer and monolayer graphene microe...

  19. Electrochemical synthesis of polydiphenylamine nanofibrils through AAO template

    International Nuclear Information System (INIS)

    Zhao Yanchun; Chen Miao; Liu Xiang; Xu Tao; Liu Weimin

    2005-01-01

    Highly ordered polydiphenylamine (PDPA) nanofibrils arrays have been fabricated within the pores of porous anodic aluminum oxide (AAO) template membrane by electrochemical polymerization. The morphology of PDPA nanofibrils array was observed using transmission electron microscopy (TEM) and its electrochemical behavior and structure were examined by cyclic voltammetry, UV-vis spectroscopy and Fourier transmission infrared spectrum. The result of TEM revealed that the obtained PDPA nanofibrils had uniform and well-aligned array. The UV-vis spectroscopy and electrochemical experimental result indicated that the spatial restraint in the pores of AAO membrane is sufficient to induce the formation of more ordered PDPA chains in the AAO membrane

  20. Electrochemical synthesis of polydiphenylamine nanofibrils through AAO template

    Energy Technology Data Exchange (ETDEWEB)

    Yanchun, Zhao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Miao, Chen [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Xiang, Liu [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Tao, Xu [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Weimin, Liu [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2005-06-15

    Highly ordered polydiphenylamine (PDPA) nanofibrils arrays have been fabricated within the pores of porous anodic aluminum oxide (AAO) template membrane by electrochemical polymerization. The morphology of PDPA nanofibrils array was observed using transmission electron microscopy (TEM) and its electrochemical behavior and structure were examined by cyclic voltammetry, UV-vis spectroscopy and Fourier transmission infrared spectrum. The result of TEM revealed that the obtained PDPA nanofibrils had uniform and well-aligned array. The UV-vis spectroscopy and electrochemical experimental result indicated that the spatial restraint in the pores of AAO membrane is sufficient to induce the formation of more ordered PDPA chains in the AAO membrane.

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

    Science.gov (United States)

    2018-01-01

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

  2. Heavy-ion microscopy

    International Nuclear Information System (INIS)

    Kraft, G.; Yang, T.C.H.; Richards, T.; Tobias, C.A.

    1980-01-01

    This chapter briefly describes the techniques of optical microscopy, scanning and transmission electron microscopy, soft x-ray microscopy and compares these latter techniques with heavy-ion microscopy. The resolution obtained with these various types of microscopy are compared and the influence of the etching procedure on total resolution is discussed. Several micrographs of mammalian cells are included

  3. Electrochemical solar energy conversion

    International Nuclear Information System (INIS)

    Gerischer, H.

    1991-01-01

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

  4. Electrochemical thermodynamic measurement system

    Science.gov (United States)

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

    2009-09-29

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

  5. Local electrochemical evaluation of a self-healing coating based on encapsulated healing-agent

    NARCIS (Netherlands)

    González-García, Y.; García, S.J.; Fischer, H.R.; Hughes, A.E.; Mol, J.M.C.

    2011-01-01

    In this work local electrochemical techniques are introduced as powerful and complementary techniques for the in-situ evaluation of self-healing systems applied for the protection of metals against corrosion. Scanning vibrating electrode technique (SVET) and scanning electrochemical microscopy

  6. Engineering Electrochemical Setups for Electron Microscopy of Liquid Processes

    DEFF Research Database (Denmark)

    Jensen, Eric; Burrows, Andrew

    This work focuses on creating tools for imaging liquid samples at atmospheric pressure and room temperature in two different electron microscopes; the scanning electron microscope (SEM) and the transmission electron microscope (TEM). The main focus of the project was the fabrication of the two sy...

  7. In SITU Transmission Electron Microscopy on Operating Electrochemical CELLS

    DEFF Research Database (Denmark)

    Gualandris, Fabrizio; Simonsen, Søren Bredmose; Mogensen, Mogens Bjerg

    2016-01-01

    Solid oxide cells (SOC) have the potential of playing a significant role in the future efficient energy system scenario. In order to become widely commercially available, an improved performance and durability of the cells has to be achieved [1]. Conventional scanning and transmission SEM and TEM...... have been often used for ex-situ post mortem characterization of SOFCs and SOECs [2,3]. However, in order to get fundamental insight of the microstructural development of SOFC/SOEC during operation conditions in situ studies are necessary [4]....

  8. In-Situ Transmission Electron Microscopy on Operating Electrochemical Cells

    DEFF Research Database (Denmark)

    Gualandris, Fabrizio; Simonsen, Søren Bredmose; Mogensen, Mogens Bjerg

    have been often used for ex-situpost mortem characterization of SOFCs and SOECs [2,3]. However, in order to get fundamental insight of themicrostructural development of SOFC/SOEC during operation conditions in-situ studies are necessary [4]. Thedevelopment of advanced TEM chips and holders makes...... it possible to undertake analysis during exposure to theSOFC/SOEC sample of reactive gas flow, elevated temperatures and electrical biasing in combination. Thisallows the study of nanostructure development under temperature and electrode polarisation conditions similarto operation conditions.In this work, we...... with animage corrector and a differential pumping system.A symmetric cell was prepared by depositing a cell consisting of three thin films on a strontium titanate (STO)single crystal substrate by pulsed laser deposition (PLD). Lanthanum strontium cobaltite La0.6Sr0.4CoO3-δ (LSC)was chosen as electrode...

  9. Preparation of Chemically Etched Tips for Ambient Instructional Scanning Tunneling Microscopy

    Science.gov (United States)

    Zaccardi, Margot J.; Winkelmann, Kurt; Olson, Joel A.

    2010-01-01

    A first-year laboratory experiment that utilizes concepts of electrochemical tip etching for scanning tunneling microscopy (STM) is described. This experiment can be used in conjunction with any STM experiment. Students electrochemically etch gold STM tips using a time-efficient method, which can then be used in an instructional grade STM that…

  10. Efficient electrochemical degradation of multiwall carbon nanotubes.

    Science.gov (United States)

    Reipa, Vytas; Hanna, Shannon K; Urbas, Aaron; Sander, Lane; Elliott, John; Conny, Joseph; Petersen, Elijah J

    2018-07-15

    As the production mass of multiwall carbon nanotubes (MWCNT) increases, the potential for human and environmental exposure to MWCNTs may also increase. We have shown that exposing an aqueous suspension of pristine MWCNTs to an intense oxidative treatment in an electrochemical reactor, equipped with an efficient hydroxyl radical generating Boron Doped Diamond (BDD) anode, leads to their almost complete mineralization. Thermal optical transmittance analysis showed a total carbon mass loss of over two orders of magnitude due to the electrochemical treatment, a result consistent with measurements of the degraded MWCNT suspensions using UV-vis absorbance. Liquid chromatography data excludes substantial accumulation of the low molecular weight reaction products. Therefore, up to 99% of the initially suspended MWCNT mass is completely mineralized into gaseous products such as CO 2 and volatile organic carbon. Scanning electron microscopy (SEM) images show sporadic opaque carbon clusters suggesting the remaining nanotubes are transformed into structure-less carbon during their electrochemical mineralization. Environmental toxicity of pristine and degraded MWCNTs was assessed using Caenorhabditis elegans nematodes and revealed a major reduction in the MWCNT toxicity after treatment in the electrochemical flow-by reactor. Published by Elsevier B.V.

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  12. Correlated Light Microscopy and Electron Microscopy

    NARCIS (Netherlands)

    Sjollema, Klaas A.; Schnell, Ulrike; Kuipers, Jeroen; Kalicharan, Ruby; Giepmans, Ben N. G.; MullerReichert, T; Verkade, P

    2012-01-01

    Understanding where, when, and how biomolecules (inter)act is crucial to uncover fundamental mechanisms in cell biology. Recent developments in fluorescence light microscopy (FLM) allow protein imaging in living cells and at the near molecular level. However, fluorescence microscopy only reveals

  13. Fundamentals of electrochemical science

    CERN Document Server

    Oldham, Keith

    1993-01-01

    Key Features* Deals comprehensively with the basic science of electrochemistry* Treats electrochemistry as a discipline in its own right and not as a branch of physical or analytical chemistry* Provides a thorough and quantitative description of electrochemical fundamentals

  14. Electrochemical Analysis of Neurotransmitters

    Science.gov (United States)

    Bucher, Elizabeth S.; Wightman, R. Mark

    2015-07-01

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

  15. Organic electrochemical transistors

    KAUST Repository

    Rivnay, Jonathan; Inal, Sahika; Salleo, Alberto; Owens, Ró isí n M.; Berggren, Magnus; Malliaras, George G.

    2018-01-01

    Organic electrochemical transistors (OECTs) make effective use of ion injection from an electrolyte to modulate the bulk conductivity of an organic semiconductor channel. The coupling between ionic and electronic charges within the entire volume

  16. Study of the ion-channel behavior on glassy carbon electrode supported bilayer lipid membranes stimulated by perchlorate anion

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhiquan; Shi, Jun; Huang, Weimin, E-mail: huangwm@jlu.edu.cn

    2015-10-01

    In this paper, a kind of didodecyldimethylammonium bromide (DDAB) layer membranes was supported on a glassy carbon electrode (GCE). We studied the ion channel behavior of the supported bilayer lipid membrane by scanning electrochemical microscopy (SCEM) in tris(2,2′-bipyridine) ruthenium(II) solution. Perchlorate anion was used as a presence of stimulus and ruthenium(II) complex cations as the probing ions for the measurement of SECM, the lipid membrane channel was opened and exhibited the behavior of distinct SECM positive feedback curve. The channel was in a closed state in the absence of perchlorate anions while reflected the behavior of SECM negative feedback curve. The rates of electron transfer reaction in the lipid membranes surface were detected and it was dependant on the potential of SECM. - Highlights: • The rates of electron transfer reaction in the lipid membranes surface were detected. • Dynamic investigations of ion-channel behavior of supported bilayer lipid membranes by scanning electrochemical microscopy • A novel way to explore the interaction between molecules and supported bilayer lipid membranes.

  17. Electrochemical polymer electrolyte membranes

    CERN Document Server

    Fang, Jianhua; Wilkinson, David P

    2015-01-01

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

  18. Oxygen-free in situ scanning tunnelling microscopy

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Ulstrup, Jens

    2007-01-01

    Scanning tunneling microscopy under full electrochemical potential control (in situ STM) has been used extensively as an efficient method to characterize microstructures at solid/liquid interfaces at the atomic and molecular levels. However, under ambient conditions oxygen may interfere in open i...

  19. Microsphere imaging with confocal microscopy and two photon microscopy

    International Nuclear Information System (INIS)

    Chun, Hyung Su; An, Kyung Won; Lee, Jai Hyung

    2002-01-01

    We have acquired images of polystyrene and fused-silica microsphere by using conventional optical microscopy, confocal microscopy and two-photon microscopy, and performed comparative analysis of these images. Different from conventional optical microscopy, confocal and two-photon microscopy had good optical sectioning capability. In addition, confocal microscopy and two-photon microscopy had better lateral resolution than conventional optical microscopy. These results are attributed to confocality and nonlinearity of confocal microscopy and two photon microscopy, respectively.

  20. Electron microscopy for Engineers

    International Nuclear Information System (INIS)

    Jones, I P

    2009-01-01

    This paper reviews the application of (mainly) Transmission Electron Microscopy (TEM) in an engineering context. The first two sections are TEM and chemical in nature; the final three sections are more general and include aspects of Scanning Electron Microscopy (SEM).

  1. Electrochemical Biosensors - Sensor Principles and Architectures

    Science.gov (United States)

    Grieshaber, Dorothee; MacKenzie, Robert; Vörös, Janos; Reimhult, Erik

    2008-01-01

    Quantification of biological or biochemical processes are of utmost importance for medical, biological and biotechnological applications. However, converting the biological information to an easily processed electronic signal is challenging due to the complexity of connecting an electronic device directly to a biological environment. Electrochemical biosensors provide an attractive means to analyze the content of a biological sample due to the direct conversion of a biological event to an electronic signal. Over the past decades several sensing concepts and related devices have been developed. In this review, the most common traditional techniques, such as cyclic voltammetry, chronoamperometry, chronopotentiometry, impedance spectroscopy, and various field-effect transistor based methods are presented along with selected promising novel approaches, such as nanowire or magnetic nanoparticle-based biosensing. Additional measurement techniques, which have been shown useful in combination with electrochemical detection, are also summarized, such as the electrochemical versions of surface plasmon resonance, optical waveguide lightmode spectroscopy, ellipsometry, quartz crystal microbalance, and scanning probe microscopy. The signal transduction and the general performance of electrochemical sensors are often determined by the surface architectures that connect the sensing element to the biological sample at the nanometer scale. The most common surface modification techniques, the various electrochemical transduction mechanisms, and the choice of the recognition receptor molecules all influence the ultimate sensitivity of the sensor. New nanotechnology-based approaches, such as the use of engineered ion-channels in lipid bilayers, the encapsulation of enzymes into vesicles, polymersomes, or polyelectrolyte capsules provide additional possibilities for signal amplification. In particular, this review highlights the importance of the precise control over the delicate

  2. Electron microscopy of surfaces

    International Nuclear Information System (INIS)

    Venables, J.A.

    1981-01-01

    Electron beam techniques used to study clean surfaces and surface processes on a microscopic scale are reviewed. Recent experimental examples and possible future developments are discussed. Special emphasis is given to (i) transmission diffraction and microscopy techniques, including atomic imaging; (ii) Auger microscopy on bulk and thin film samples; (iii) secondary electron microscopy, especially low energy secondaries for work-function imaging and photoelectron imaging; and (iv) reflection electron microscopy and diffraction. (orig.)

  3. Dictionary of Microscopy

    Science.gov (United States)

    Heath, Julian

    2005-10-01

    The past decade has seen huge advances in the application of microscopy in all areas of science. This welcome development in microscopy has been paralleled by an expansion of the vocabulary of technical terms used in microscopy: terms have been coined for new instruments and techniques and, as microscopes reach even higher resolution, the use of terms that relate to the optical and physical principles underpinning microscopy is now commonplace. The Dictionary of Microscopy was compiled to meet this challenge and provides concise definitions of over 2,500 terms used in the fields of light microscopy, electron microscopy, scanning probe microscopy, x-ray microscopy and related techniques. Written by Dr Julian P. Heath, Editor of Microscopy and Analysis, the dictionary is intended to provide easy navigation through the microscopy terminology and to be a first point of reference for definitions of new and established terms. The Dictionary of Microscopy is an essential, accessible resource for: students who are new to the field and are learning about microscopes equipment purchasers who want an explanation of the terms used in manufacturers' literature scientists who are considering using a new microscopical technique experienced microscopists as an aide mémoire or quick source of reference librarians, the press and marketing personnel who require definitions for technical reports.

  4. Materials for electrochemical capacitors

    Science.gov (United States)

    Simon, Patrice; Gogotsi, Yury

    2008-11-01

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

  5. Electrochemical reduction of NOx

    DEFF Research Database (Denmark)

    Traulsen, Marie Lund

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

  6. Electrochemical behavior of monolayer and bilayer graphene.

    Science.gov (United States)

    Valota, Anna T; Kinloch, Ian A; Novoselov, Kostya S; Casiraghi, Cinzia; Eckmann, Axel; Hill, Ernie W; Dryfe, Robert A W

    2011-11-22

    Results of a study on the electrochemical properties of exfoliated single and multilayer graphene flakes are presented. Graphene flakes were deposited on silicon/silicon oxide wafers to enable fast and accurate characterization by optical microscopy and Raman spectroscopy. Conductive silver paint and silver wires were used to fabricate contacts; epoxy resin was employed as a masking coating in order to expose a stable, well-defined area of graphene. Both multilayer and monolayer graphene microelectrodes showed quasi-reversible behavior during voltammetric measurements in potassium ferricyanide. However, the standard heterogeneous charge transfer rate constant, k°, was estimated to be higher for monolayer graphene flakes. © 2011 American Chemical Society

  7. Pulse electrochemical meso/micro/nano ultraprecision machining technology.

    Science.gov (United States)

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

    2013-11-01

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

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

    Science.gov (United States)

    Niaz, Akbar; Khan, Sajid Ullah

    2016-01-01

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

  9. Electrochemical energy storage

    CERN Document Server

    Tarascon, Jean-Marie

    2015-01-01

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

  10. Electrochemical Hydrogen Evolution

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  11. Electrochemical preparation of uniform CuO/Cu2O heterojunction on β-cyclodextrin-modified carbon fibers

    KAUST Repository

    Chen, Fang-Ping; Jin, Guan-Ping; Su, Jing-Yu; Feng, Xiaoshuang

    2016-01-01

    materials were characterized by field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electrochemical techniques. The potential application in pollution treatment

  12. Electrochemically deposited hybrid nickel-cobalt hexacyanoferrate nanostructures for electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-30

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

  13. Electrochemically deposited hybrid nickel-cobalt hexacyanoferrate nanostructures for electrochemical supercapacitors

    International Nuclear Information System (INIS)

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

    2011-01-01

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

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  15. Microstructure and mechanical properties of friction welded AISI 1040/AISI 304L steels before and after electrochemical corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Sarsilmaz, Furkan [Firat Univ., Elazig (Turkey). Dept. of Mechatronics Engineering; Kirik, Ihsan [Batman Univ. (Turkey); Ozdemir, Niyazi [Firat Univ., Elazig (Turkey)

    2018-03-01

    The aim of the present study is to investigate the effect of welding parameters both on the electrochemical corrosion behavior and tensile strength of pre- and post-electrochemical corrosion of friction welded dissimilar steels. The microstructural changes of AISI 1040/AISI 304L friction welded couples and also parent materials were analyzed by using scanning electron microscopy. The electrochemical behaviors of AISI1040/AISI304L joints were comparatively investigated by potentiodynamic polarization curve test and by electrochemical impedance spectra. Moreover, tensile strength experiments were carried out determining the behavior of friction welded joints of pre- and post-electrochemical corrosion and results indicated that the maximum tensile test value of the dissimilar welded pre-electrochemical corrosion was higher than those of post-electrochemical corrosion and was also very close to AISI 1040 parent material value.

  16. Electrochemical Power Sources

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 7. Electrochemical Power Sources - Rechargeable Batteries. A K Shukla S K Martha. General Article Volume 6 Issue 7 July 2001 pp 52-63. Fulltext. Click here to view fulltext PDF. Permanent link:

  17. Electro-chemical grinding

    Science.gov (United States)

    Feagans, P. L.

    1972-01-01

    Electro-chemical grinding technique has rotation speed control, constant feed rates, and contour control. Hypersonic engine parts of nickel alloys can be almost 100% machined, keeping tool pressure at virtual zero. Technique eliminates galling and permits constant surface finish and burr-free interrupted cutting.

  18. New microscopy for nanoimaging

    CERN Document Server

    Kinjo, Y; Watanabe, M

    2002-01-01

    Two types of new microscopy, namely, X-ray contact microscopy (XRCM) in combination with atomic force microscopy (AFM) and X-ray projection microscopy (XRPM) using synchrotron radiation and zone plate optics were used to image the fine structures of human chromosomes. In the XRCM plus AFM system, location of X-ray images on a photoresist has become far easier than that with our previous method using transmission electron microscopy coupled with the replica method. In addition, the images obtained suggested that the conformation of chromatin fiber differs from the current textbook model regarding the architecture of a eukaryotic chromosome. X-ray images with high contrast of the specimens could be obtained with XRPM. The resolution of each microscopy was about 30 and 200-300 nm for XRCM plus AFM and XRPM, respectively. (author)

  19. Microscopy and Image Analysis.

    Science.gov (United States)

    McNamara, George; Difilippantonio, Michael; Ried, Thomas; Bieber, Frederick R

    2017-07-11

    This unit provides an overview of light microscopy, including objectives, light sources, filters, film, and color photography for fluorescence microscopy and fluorescence in situ hybridization (FISH). We believe there are excellent opportunities for cytogeneticists, pathologists, and other biomedical readers, to take advantage of specimen optical clearing techniques and expansion microscopy-we briefly point to these new opportunities. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

  20. CARS microscopy for imaging

    International Nuclear Information System (INIS)

    Arzumanyan Grigory; Voskanyan Karine

    2013-01-01

    Optical microscopy grows in its importance with the development of modern nanotechnology, biotechnology, methods of diagnostics and treatment of most dangerous diseases for mankind. There are several important goals of optical microscopy for biomedical studies among which the next three may be distinguished: fast imaging with high lateral spatial resolution, 3-D sectioning capability and high contrast for chemical selectivity. To meet these specific requirements, various types of both linear and nonlinear optical microscopy were elaborated. (authors)

  1. Fluorescence (Multiwave) Confocal Microscopy.

    Science.gov (United States)

    Welzel, J; Kästle, Raphaela; Sattler, Elke C

    2016-10-01

    In addition to reflectance confocal microscopy, multiwave confocal microscopes with different laser wavelengths in combination with exogenous fluorophores allow fluorescence mode confocal microscopy in vivo and ex vivo. Fluorescence mode confocal microscopy improves the contrast between the epithelium and the surrounding soft tissue and allows the depiction of certain structures, like epithelial tumors, nerves, and glands. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Electron Microscopy Center (EMC)

    Data.gov (United States)

    Federal Laboratory Consortium — The Electron Microscopy Center (EMC) at Argonne National Laboratory develops and maintains unique capabilities for electron beam characterization and applies those...

  3. Coherent light microscopy

    CERN Document Server

    Ferraro, Pietro; Zalevsky, Zeev

    2011-01-01

    This book deals with the latest achievements in the field of optical coherent microscopy. While many other books exist on microscopy and imaging, this book provides a unique resource dedicated solely to this subject. Similarly, many books describe applications of holography, interferometry and speckle to metrology but do not focus on their use for microscopy. The coherent light microscopy reference provided here does not focus on the experimental mechanics of such techniques but instead is meant to provide a users manual to illustrate the strengths and capabilities of developing techniques. Th

  4. Bridging fluorescence microscopy and electron microscopy

    NARCIS (Netherlands)

    Giepmans, Ben N. G.

    Development of new fluorescent probes and fluorescence microscopes has led to new ways to study cell biology. With the emergence of specialized microscopy units at most universities and research centers, the use of these techniques is well within reach for a broad research community. A major

  5. Electrochemical Biosensors - Sensor Principles and Architectures

    Directory of Open Access Journals (Sweden)

    Erik Reimhult

    2008-03-01

    Full Text Available Quantification of biological or biochemical processes are of utmost importancefor medical, biological and biotechnological applications. However, converting the biologicalinformation to an easily processed electronic signal is challenging due to the complexity ofconnecting an electronic device directly to a biological environment. Electrochemical biosensorsprovide an attractive means to analyze the content of a biological sample due to thedirect conversion of a biological event to an electronic signal. Over the past decades severalsensing concepts and related devices have been developed. In this review, the most commontraditional techniques, such as cyclic voltammetry, chronoamperometry, chronopotentiometry,impedance spectroscopy, and various field-effect transistor based methods are presented alongwith selected promising novel approaches, such as nanowire or magnetic nanoparticle-basedbiosensing. Additional measurement techniques, which have been shown useful in combinationwith electrochemical detection, are also summarized, such as the electrochemical versionsof surface plasmon resonance, optical waveguide lightmode spectroscopy, ellipsometry,quartz crystal microbalance, and scanning probe microscopy.The signal transduction and the general performance of electrochemical sensors are often determinedby the surface architectures that connect the sensing element to the biological sampleat the nanometer scale. The most common surface modification techniques, the various electrochemicaltransduction mechanisms, and the choice of the recognition receptor moleculesall influence the ultimate sensitivity of the sensor. New nanotechnology-based approaches,such as the use of engineered ion-channels in lipid bilayers, the encapsulation of enzymesinto vesicles, polymersomes, or polyelectrolyte capsules provide additional possibilities forsignal amplification.In particular, this review highlights the importance of the precise control over the

  6. Electrochemical Oxidation of Glycerol Using Gold Electrode

    International Nuclear Information System (INIS)

    Mohamed Rozali Othman; Amirah Ahmad

    2015-01-01

    Cyclic voltammetry, potential linear V and chronocuolometry methods were carried out to gain electrochemical behavior of glycerol at a gold electrode. Potassium hydroxide and sulfuric acid were chosen to be the electrolyte for the electro-oxidation of this organic compound. Besides gold plate electrode, gold composite electrode (Au-PVC) was also used as the working electrode. The Au-PVC composite electrode was characterized by Scanning Electron Microscopy (SEM) to determine its morphological aspects before and after used in electrochemical oxidation of glycerol. In alkaline solution, the adsorption of hydroxide species onto the surface of both gold plate and composite Au-PVC electrodes occurs at potential around 500 mV vs SCE. However, at gold plate electrode, there was a small, broad peak before the drastic escalation of current densities which indicates the charge transfer of the chemisorbed OH - anion. In acidic media, the gold oxide was formed after potential 1.0 V. From the cyclic voltammogram glycerol undergo oxidation twice in potassium hydroxide at gold plate and Au-PVC composite electrodes, while in sulfuric acid, oxidation reaction happened once for glycerol on the gold plate electrode. Overall, electrochemical oxidation of glycerol was more effective in alkaline media. Tafel graph which plotted from potential linear V method shows that Au-PVC composite electrode is better than gold plate electrode for the electro-oxidation of glycerol in alkaline solution. Electrochemical oxidation of glycerol products as analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) produced several carboxylic acids and phenolic compounds. (author)

  7. Fabrication and electrochemical performance of graphene—ZnO nanocomposites

    International Nuclear Information System (INIS)

    Li Zhen-Peng; Men Chuan-Ling; Wang Wan; Cao Jun

    2014-01-01

    Graphene—ZnO nanocomposites were synthesized successfully through a one-step solvothermal approach. The morphology, structure, and composition of the prepared nanocomposites were investigated by scanning electron microscopy (SEM), transmission electron microscope (TEM), laser micro Raman spectroscopy, and Fourier transform infra-red spectroscopy (FT-IR). The outcomes confirmed that this approach is comparatively steady, practicable, and operable compared with other reported methods. The electrochemical performance of the graphene-ZnO electrodes was analyzed through cyclic voltammetry, altering-current (AC) impedance, and chronopotentiometry tests. The graphene—ZnO electrodes exhibited an improved electrode performance with higher specific capacitance (115 F·g −1 ), higher electrochemical stability, and higher energy density than the graphene electrodes and most reported graphene—ZnO electrodes. Graphene—ZnO nanocomposites have a steady reversible charge/discharge behavior, which makes them promising candidates for electrochemical capacitors (ECs). (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  8. Capsid protein oxidation in feline calicivirus using an electrochemical inactivation treatment

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-02-11

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

  9. Corrosion protection of ENIG surface finishing using electrochemical methods

    International Nuclear Information System (INIS)

    Bui, Q.V.; Nam, N.D.; Choi, D.H.; Lee, J.B.; Lee, C.Y.; Kar, A.; Kim, J.G.; Jung, S.B.

    2010-01-01

    Four types of thin film coating were carried out on copper for electronic materials by the electroless plating method at a pH range from 3 to 9. The coating performance was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization testing in a 3.5 wt.% NaCl solution. In addition, atomic force microscopy and X-ray diffraction were also used to analyze the coating surfaces. The electrochemical behavior of the coatings was improved using the electroless nickel plating solution of pH 5. The electroless nickel/immersion gold on the copper substrate exhibited high protective efficiency, charge transfer resistance and very low porosity, indicating an increase in corrosion resistance. Atomic force microscopy and X-ray diffraction analyses confirmed the surface uniformity and the formation of the crystalline-refined NiP {1 2 2} phase at pH 5.

  10. Study on the electrochemical of the metal deposition from ionic liquids for lithium, titanium and dysprosium

    International Nuclear Information System (INIS)

    Berger, Claudia A.

    2017-01-01

    The thesis was aimed to the characterization of electrochemically deposited film of lithium, titanium and dysprosium on Au(111) from different ionic liquids, finally dysprosium on neodymium-iron-boron magnate for industrial applications. The investigation of the deposits were performed using cyclic voltametry, in-situ scanning tunneling microscopy, electrochemical quartz microbalance, XPS and Auger electron spectroscopy. The sample preparation is described in detail. The deposition rate showed a significant temperature dependence.

  11. A reusable device for electrochemical applications of hydrogel supported black lipid membranes

    DEFF Research Database (Denmark)

    Mech-Dorosz, Agnieszka; Heiskanen, Arto; Bäckström, Sania

    2015-01-01

    the ETFE substrate and a gold electrode microchip, thus allowing direct electrochemical studies with the integrated working electrodes. Using electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy and contact angle measurements, we demonstrate the optimized chemical modifications...... of the gold electrode microchips and plasma modification of the ETFE aperture arrays facilitating covalent "sandwiching" of the hydrogel. Both fluorescence microscopy and EIS were used to demonstrate the induced spontaneous thinning of a deposited lipid solution, leading to formation of stabilized hs...

  12. The possibility of multi-layer nanofabrication via atomic force microscope-based pulse electrochemical nanopatterning

    Science.gov (United States)

    Kim, Uk Su; Morita, Noboru; Lee, Deug Woo; Jun, Martin; Park, Jeong Woo

    2017-05-01

    Pulse electrochemical nanopatterning, a non-contact scanning probe lithography process using ultrashort voltage pulses, is based primarily on an electrochemical machining process using localized electrochemical oxidation between a sharp tool tip and the sample surface. In this study, nanoscale oxide patterns were formed on silicon Si (100) wafer surfaces via electrochemical surface nanopatterning, by supplying external pulsed currents through non-contact atomic force microscopy. Nanoscale oxide width and height were controlled by modulating the applied pulse duration. Additionally, protruding nanoscale oxides were removed completely by simple chemical etching, showing a depressed pattern on the sample substrate surface. Nanoscale two-dimensional oxides, prepared by a localized electrochemical reaction, can be defined easily by controlling physical and electrical variables, before proceeding further to a layer-by-layer nanofabrication process.

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

    Directory of Open Access Journals (Sweden)

    H. Adelkhani

    2016-06-01

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

  14. Confocal Raman microscopy

    CERN Document Server

    Dieing, Thomas; Hollricher, Olaf

    2018-01-01

    This second edition provides a cutting-edge overview of physical, technical and scientific aspects related to the widely used analytical method of confocal Raman microscopy. The book includes expanded background information and adds insights into how confocal Raman microscopy, especially 3D Raman imaging, can be integrated with other methods to produce a variety of correlative microscopy combinations. The benefits are then demonstrated and supported by numerous examples from the fields of materials science, 2D materials, the life sciences, pharmaceutical research and development, as well as the geosciences.

  15. Facile electrochemical synthesis of tellurium nanorods and their photoconductive properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, H.H. [Center for Photon Manufacturing Science and Technology, School of Materials Science and Engineering, Jiangsu University, Zhenjiang - 212013 (China); Zhang, P. [Dongguan University of Technology, Dongguan-523808 (China); School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou - 510275 (China); Liang, C.L. [Instrumental Analysis and Research Center, SunYat-sen University, Guangzhou - 510275 (China); Yang, J. [School of Materials Science and Engineering, Jiangsu University, Zhenjiang - 212013 (China); Zhou, M. [Center for Photon Manufacturing Science and Technology, School of Materials Science and Engineering, Jiangsu University, Zhenjiang - 212013 (China); The State Key Laboratory of Tribology, Tsinghua University, Beijing - 10084 (China); Lu, X.H. [School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou - 510275 (China); Hope, G.A. [School of Biomolecular and Physical Sciences, Griffith University, Nathan - Qld 4111 (Australia)

    2012-10-15

    Tellurium nanorods have been successfully fabricated by template and surfactant-free electrochemical technique from an aqueous solution at room temperature. The as-prepared tellurium nanorods were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectrometry, UV-vis spectroscopy and photoluminescence spectroscopy. Films based on tellurium nanorods were constructed to study the photoresponse and I-V curves. These photoresponse measurements demonstrate that tellurium nanorods exhibited enhanced conductivity under illumination compared to in the dark measurement. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Electrochemical deposition of Prussian blue on hydrogen terminated silicon(111)

    International Nuclear Information System (INIS)

    Zhao Jianwei; Zhang Yan; Shi Chuanguo; Chen, Hongyuan; Tong Lianming; Zhu Tao; Liu Zhongfan

    2006-01-01

    Electrochemical deposition of Prussian blue (PB) was performed by cyclic voltammetry on hydrogen terminated n-type Si(111) surface. The characterization of the samples based on atomic force microscopy and X-ray diffraction spectroscopy showed a nanocrystal form of the PB films on the silicon surface. The thickness of PB films as a function of the potential cycling number was monitored simultaneously by Raman spectroscopy, proving that the growth of the films is in a good controllable manner

  17. A glassy carbon electrode modified with an iron N4-macrocycle and reduced graphene oxide for voltammetric sensing of dissolved oxygen

    International Nuclear Information System (INIS)

    Silva, Saimon M.; Aguiar, Lucas F.; Carvalho, Rita M. S.; Tanaka, Auro A.; Damos, Flavio S.; Luz, Rita C. S.

    2016-01-01

    The authors describe a platform for the electrochemical reduction of oxygen. It is based on the use of a glassy carbon electrode (GCE) that was modified in a single-step microwave assisted reaction with a N4-macrocycle containing iron(III) (FeN4) and with reduced graphene oxide. The FeN4/rGO composite was characterized by cyclic voltammetry, differential pulse voltammetry, and scanning electrochemical microscopy (SECM). Cyclic voltammetry showed the composite to enable efficient reduction of O_2 at a very low overpotential (−0.05 V vs. Ag/AgCl). SECM measurements were carried out to map (in the redox competition mode) the activity of a GCE microelectrode modified with FeN4/rGO. Under optimized conditions, the response to dissolved O_2 ranges from 0.8 up to 25 mg⋅L"-"1, and the limit of detection is 0.2 mg⋅L"-"1. (author)

  18. Electrochemical migration of tin in electronics and microstructure of the dendrites

    DEFF Research Database (Denmark)

    Minzari, Daniel; Grumsen, Flemming Bjerg; Jellesen, Morten Stendahl

    2011-01-01

    The macro-, micro-, and nano-scale morphology and structure of tin dendrites, formed by electrochemical migration on a surface mount ceramic chip resistor having electrodes consisting of tin with small amounts of Pb (∼2wt.%) was investigated by scanning electron microscopy and transmission electr...... by the dehydration of the hydrated oxide originally formed in solution ex-situ in ambient air.......The macro-, micro-, and nano-scale morphology and structure of tin dendrites, formed by electrochemical migration on a surface mount ceramic chip resistor having electrodes consisting of tin with small amounts of Pb (∼2wt.%) was investigated by scanning electron microscopy and transmission electron...... microscopy including Energy dispersive X-ray spectroscopy and electron diffraction. The tin dendrites were formed under 5 or 12V potential bias in 10ppm by weight NaCl electrolyte as a micro-droplet on the resistor during electrochemical migration experiments. The dendrites formed were found to have...

  19. Electrochemical Corrosion of Stainless Steel in Thiosulfate Solutions Relevant to Gold Leaching

    Science.gov (United States)

    Choudhary, Lokesh; Wang, Wei; Alfantazi, Akram

    2016-01-01

    This study aims to characterize the electrochemical corrosion behavior of stainless steel in the ammoniacal thiosulfate gold leaching solutions. Electrochemical corrosion response was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy, while the semi-conductive properties and the chemical composition of the surface film were characterized using Mott-Schottky analysis and X-ray photoelectron spectroscopy, respectively. The morphology of the corroded specimens was analyzed using scanning electron microscopy. The stainless steel 316L showed no signs of pitting in the ammoniacal thiosulfate solutions.

  20. Synthesis and electrochemical properties of tin oxide-based composite by rheological technique

    International Nuclear Information System (INIS)

    He Zeqiang; Li Xinhai; Xiong Lizhi; Wu Xianming; Xiao Zhuobing; Ma Mingyou

    2005-01-01

    Novel rheological technique was developed to synthesize tin oxide-based composites. The microstructure, morphology, and electrochemical performance of the materials were investigated by X-ray diffraction, scanning electron microscopy and electrochemical methods. The particles of tin oxide-based materials form an inactive matrix. The average size of the particles is about 150 nm. The material delivers a charge capacity of more than 570 mAh g -1 . The capacity loss per cycle is about 0.15% after being cycled 30 times. The good electrochemical performance indicates that this kind of tin oxide-based material is promising anode for lithium-ion battery

  1. Electrochemical deposition of coatings of highly entropic alloys from non-aqueous solutions

    Directory of Open Access Journals (Sweden)

    Jeníček V.

    2016-03-01

    Full Text Available The paper deals with electrochemical deposition of coatings of highly entropic alloys. These relatively new materials have been recently intensively studied. The paper describes the first results of electrochemical coating with highly entropic alloys by deposition from non-aqueous solutions. An electrochemical device was designed and coatings were deposited. The coatings were characterised with electronic microscopy scanning, atomic absorption spectrometry and X-ray diffraction methods and the combination of methods of thermic analysis of differential scanning calorimetry and thermogravimetry.

  2. Modified porous silicon for electrochemical sensor of para-nitrophenol

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  3. Modified porous silicon for electrochemical sensor of para-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Belhousse, S., E-mail: all_samia_b@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Belhaneche-Bensemra, N., E-mail: nbelhaneche@yahoo.fr [Ecole Nationale Polytechnique (ENP), 10, Avenue Hassen Badi, B.P. 182, 16200, El Harrach, Algiers (Algeria); Lasmi, K., E-mail: kahinalasmi@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Mezaache, I., E-mail: lyeso_44@hotmail.fr [Ecole Nationale Polytechnique (ENP), 10, Avenue Hassen Badi, B.P. 182, 16200, El Harrach, Algiers (Algeria); Sedrati, T., E-mail: tarek_1990m@hotmail.fr [Ecole Nationale Polytechnique (ENP), 10, Avenue Hassen Badi, B.P. 182, 16200, El Harrach, Algiers (Algeria); Sam, S., E-mail: Sabrina.sam@polytechnique.edu [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Tighilt, F.-Z., E-mail: mli_zola@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Gabouze, N., E-mail: ngabouze@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria)

    2014-11-15

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

  4. Force modulation and electrochemical gating of conductance in a cytochrome

    Science.gov (United States)

    Davis, Jason J.; Peters, Ben; Xi, Wang

    2008-09-01

    Scanning probe methods have been used to measure the effect of electrochemical potential and applied force on the tunnelling conductance of the redox metalloprotein yeast iso-1-cytochrome c (YCC) at a molecular level. The interaction of a proximal probe with any sample under test will, at this scale, be inherently perturbative. This is demonstrated with conductive probe atomic force microscopy (CP-AFM) current-voltage spectroscopy in which YCC, chemically adsorbed onto pristine Au(111) via its surface cysteine residue, is observed to become increasingly compressed as applied load is increased, with concomitant decrease in junction resistance. Electrical contact at minimal perturbation, where probe-molecule coupling is comparable to that in scanning tunnelling microscopy, brings with it the observation of negative differential resistance, assigned to redox-assisted probe-substrate tunnelling. The role of the redox centre in conductance is also resolved in electrochemical scanning tunnelling microscopy assays where molecular conductance is electrochemically gateable through more than an order of magnitude.

  5. International Multidisciplinary Microscopy Congress

    CERN Document Server

    Oral, Ahmet; Ozer, Mehmet; InterM; INTERM2013

    2014-01-01

    The International Multidisciplinary Microscopy Congress (INTERM2013) was organized on October 10-13, 2013. The aim of the congress was to bring together scientists from various branches to discuss the latest advances in the field of microscopy. The contents of the congress have been broadened to a more "interdisciplinary" scope, so as to allow all scientists working on related subjects to participate and present their work. These proceedings include 39 peer-reviewed technical papers, submitted by leading academic and research institutions from over 12 countries and representing some of the most cutting-edge research available. The 39 papers are grouped into the following sections: - Applications of Microscopy in the Physical Sciences - Applications of Microscopy in the Biological Sciences

  6. Hydroxyapatite formation on biomedical Ti–Ta–Zr alloys by magnetron sputtering and electrochemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun-Ju [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Jeong, Yong-Hoon [Biomechanics and Tissue Engineering Laboratory, Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Brantley, William A. [Division of Prosthodontics and Restorative Science, College of Dentistry, The Ohio State University, Columbus, OH (United States)

    2014-12-01

    The purpose of this study was to investigate hydroxyapatite formation on Ti-25Ta-xZr titanium alloys resulting from radio-frequency magnetron sputtering and electrochemical deposition. Electrochemical deposition of hydroxyapatite (HA) was first carried out using a cyclic voltammetry (CV) method at 80 °C in 5 mM Ca (NO{sub 3}){sub 2} + 3 mM NH{sub 4}H{sub 2}PO{sub 4}. Then a physical vapor deposition (PVD) coating was obtained by a radio-frequency (RF) magnetron sputtering technique. The microstructures, phase transformations, and morphologies of the hydroxyapatite films deposited on the titanium alloys were analyzed by optical microscopy (OM), X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDS) and field-emission scanning electron microscopy (FE-SEM). The morphologies of electrochemically deposited HA showed plate-like shapes on the titanium alloys, and the morphologies of the RF-sputtered HA coating had the appearance droplet particles on the plate-like precipitates that had formed by electrochemical deposition. For the RF-sputtered HA coatings, the Ca/P ratio was increased, compared to that for the electrochemically deposited HA surface. Moreover, the RF-sputtered HA coating, consisting of agglomerated droplet particles on the electrochemically deposited HA surface, had better wettability compared to the bulk titanium alloy surface. - Highlights: • Hydroxyapatite (HA) was deposited on Ti–Ta–Zr alloys by radio-frequency (RF) magnetron sputtering and a cyclic voltammetry. • The morphologies of the RF-sputtered HA coating on electrochemical deposits presented plate-like shapes with a droplet particle. • The Ca/P ratio for RF-sputtered HA coatings was greater than that for electrochemical deposited HA coatings. • The RF-sputtered and electrochemical HA coatings had superior wettability compared to the electrochemically deposited coatings.

  7. Hydroxyapatite formation on biomedical Ti–Ta–Zr alloys by magnetron sputtering and electrochemical deposition

    International Nuclear Information System (INIS)

    Kim, Hyun-Ju; Jeong, Yong-Hoon; Choe, Han-Cheol; Brantley, William A.

    2014-01-01

    The purpose of this study was to investigate hydroxyapatite formation on Ti-25Ta-xZr titanium alloys resulting from radio-frequency magnetron sputtering and electrochemical deposition. Electrochemical deposition of hydroxyapatite (HA) was first carried out using a cyclic voltammetry (CV) method at 80 °C in 5 mM Ca (NO 3 ) 2 + 3 mM NH 4 H 2 PO 4 . Then a physical vapor deposition (PVD) coating was obtained by a radio-frequency (RF) magnetron sputtering technique. The microstructures, phase transformations, and morphologies of the hydroxyapatite films deposited on the titanium alloys were analyzed by optical microscopy (OM), X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDS) and field-emission scanning electron microscopy (FE-SEM). The morphologies of electrochemically deposited HA showed plate-like shapes on the titanium alloys, and the morphologies of the RF-sputtered HA coating had the appearance droplet particles on the plate-like precipitates that had formed by electrochemical deposition. For the RF-sputtered HA coatings, the Ca/P ratio was increased, compared to that for the electrochemically deposited HA surface. Moreover, the RF-sputtered HA coating, consisting of agglomerated droplet particles on the electrochemically deposited HA surface, had better wettability compared to the bulk titanium alloy surface. - Highlights: • Hydroxyapatite (HA) was deposited on Ti–Ta–Zr alloys by radio-frequency (RF) magnetron sputtering and a cyclic voltammetry. • The morphologies of the RF-sputtered HA coating on electrochemical deposits presented plate-like shapes with a droplet particle. • The Ca/P ratio for RF-sputtered HA coatings was greater than that for electrochemical deposited HA coatings. • The RF-sputtered and electrochemical HA coatings had superior wettability compared to the electrochemically deposited coatings

  8. Electrochemical Sensors for Clinic Analysis

    Directory of Open Access Journals (Sweden)

    Guang Li

    2008-03-01

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

  9. Electrochemical reduction of NO{sub x}

    Energy Technology Data Exchange (ETDEWEB)

    Lund Traulsen, M.

    2012-04-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-08-01

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

  11. MnO{sub 2} nanotube and nanowire arrays by electrochemical deposition for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Hui; Feng, Jinkui; Wang, Hailong; Lai, Man On; Lu, Li [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore)

    2010-07-01

    Highly ordered MnO{sub 2} nanotube and nanowire arrays are successfully synthesized via a electrochemical deposition technique using porous alumina templates. The morphologies and microstructures of the MnO{sub 2} nanotube and nanowire arrays are investigated by field emission scanning electron microscopy and transmission electron microscopy. Electrochemical characterization demonstrates that the MnO{sub 2} nanotube array electrode has superior capacitive behaviour to that of the MnO{sub 2} nanowire array electrode. In addition to high specific capacitance, the MnO{sub 2} nanotube array electrode also exhibits good rate capability and good cycling stability, which makes it promising candidate for supercapacitors. (author)

  12. Electrochemical destruction of nitrosamines

    Energy Technology Data Exchange (ETDEWEB)

    Lejen, T; Volchek, K; Ladanowski, C; Velicogna, D; Whittaker, H [Environment Canada, Ottawa, ON (Canada). Emergencies Engineering Div.

    1996-09-01

    Treatment conditions for the electrolytic destruction of nitrosamines were studied. The joint investigation between Canada and the Ukraine was part of an assessment of hazardous contaminants at former Soviet ICBM missile sites. The electrochemical destruction of N-dimethylnitrosamines (NDMA) on carbon/platinum electrodes was studied under basic and acidic conditions by UV spectroscopy, gas chromatography, mass spectroscopy, and colorimetry. Experiments with a 100 ppm NDMA solution showed that electrolytic-reduction was pH sensitive within a range of pH 0.5 to 4.0. Electrolysis was effective for the reduction of NDMA in strong acidic conditions. 30 refs., 1 tab., 4 figs.

  13. Electrochemical Science and Technology

    CERN Document Server

    Oldham, Keith; Bond, Alan

    2011-01-01

    The book addresses the scientific principles underlying electrochemistry. Starting with the basic concepts of electricity, the early chapters discuss the physics and chemistry of the materials from which electrochemical cells are constructed and the properties that make these materials appropriate as cell components. Much of the importance of electrochemistry lies in the conversion of electrical energy into chemical energy and vice versa; the thermodynamics of these processes is described, in the context of a wide range of applications of these interconversions. An electrode is a surface at wh

  14. Electrochemical photovoltaic cells and electrodes

    Science.gov (United States)

    Skotheim, Terje A.

    1984-01-01

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

  15. Thermodynamics of irreversible electrochemical phenomena

    NARCIS (Netherlands)

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

    1953-01-01

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

  16. Electrochemical biosensors for hormone analyses.

    Science.gov (United States)

    Bahadır, Elif Burcu; Sezgintürk, Mustafa Kemal

    2015-06-15

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

  17. Electrochemical characterization of aminated acrylic conducting polymer

    International Nuclear Information System (INIS)

    Rashid, Norma Mohammad; Heng, Lee Yook; Ling, Tan Ling

    2015-01-01

    New attempt has been made to synthesize aminated acrylic conducting polymer (AACP) using precursor of phenylvinylsulfoxide (PVS). The process was conducted via the integration of microemulsion and photopolymerization techniques. It has been utilized for covalent immobilization of amino groups by the adding of N-achryiloxisuccinimide (NAS). Thermal eliminating of benzene sulfenic acids from PVS has been done at 250 °C to form electroactive polyacetylene (PA) segment. Characterization of AACP has been conducted using fourier transform infrared (FTIR), scanning electron microscopy (SEM) and linear sweep cyclic voltammetry (CV). A range of 0.3-1.25μm particle size obtained from SEM characterization. A quasi-reversible system performed as shown in electrochemical study

  18. Electrochemical characterization of aminated acrylic conducting polymer

    Energy Technology Data Exchange (ETDEWEB)

    Rashid, Norma Mohammad [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Lestari Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor Darul Ehsan (Malaysia); Heng, Lee Yook [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Lestari Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor Darul Ehsan (Malaysia); Southeast Asia Disaster Prevention Research Initiative, Lestari Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor Darul Ehsan (Malaysia); Ling, Tan Ling [Southeast Asia Disaster Prevention Research Initiative, Lestari Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor Darul Ehsan (Malaysia)

    2015-09-25

    New attempt has been made to synthesize aminated acrylic conducting polymer (AACP) using precursor of phenylvinylsulfoxide (PVS). The process was conducted via the integration of microemulsion and photopolymerization techniques. It has been utilized for covalent immobilization of amino groups by the adding of N-achryiloxisuccinimide (NAS). Thermal eliminating of benzene sulfenic acids from PVS has been done at 250 °C to form electroactive polyacetylene (PA) segment. Characterization of AACP has been conducted using fourier transform infrared (FTIR), scanning electron microscopy (SEM) and linear sweep cyclic voltammetry (CV). A range of 0.3-1.25μm particle size obtained from SEM characterization. A quasi-reversible system performed as shown in electrochemical study.

  19. Tuning the physico-electrochemical properties of novel cobalt (II) octa[(3,5-biscarboxylate)-phenoxy] phthalocyanine complex using phenylamine-functionalised SWCNTs

    CSIR Research Space (South Africa)

    Agboola, BO

    2010-03-01

    Full Text Available OBPPc-SWCNT-phenylamine hybrid were evaluated using spectroscopy (IR and UV–vis), field emission scanning electron microscopy and electrochemistry (cyclic voltammetry and electrochemical impedance spectroscopy). Integration of SWCNT-phenylamine resulted in the physical...

  20. Undoped CVD diamond films for electrochemical applications

    International Nuclear Information System (INIS)

    Mosinska, Lidia; Fabisiak, Kazimierz; Paprocki, Kazimierz; Kowalska, Magdalena; Popielarski, Pawel; Szybowicz, Miroslaw

    2013-01-01

    By using different deposition conditions, the CVD diamond films with different qualities and orientation were grown by the hot-filament CVD technique. The object of this article is to summarize and discuss relation between structural, physical and electrochemical properties of different diamond electrodes. The physical properties of the Hot Filament CVD microcrystalline diamond films are analyzed by scanning electron microscopy and Raman spectroscopy. In presented studies two different electrodes were used of the diamond grain sizes around 200 nm and 10 μm, as it was estimated from SEM picture. The diamond layers quality was checked on basis of FWHM (Full width at Half Maximum) of 1332 cm −1 diamond Raman peak. The ratio of sp 3 /sp 2 carbon bonds was determined by 1550 cm −1 G band and 1350 cm −1 D band in the Raman spectrum. The electrochemical properties were analyzed using (CV) cyclic voltammetry measurements in aqueous solutions. The sensitivity of undoped diamond electrodes depends strongly on diamond film quality and concentration of amorphous carbon phase in the diamond layer

  1. Zinc oxide nanostructures for electrochemical cortisol biosensing

    Science.gov (United States)

    Vabbina, Phani Kiran; Kaushik, Ajeet; Tracy, Kathryn; Bhansali, Shekhar; Pala, Nezih

    2014-05-01

    In this paper, we report on fabrication of a label free, highly sensitive and selective electrochemical cortisol immunosensors using one dimensional (1D) ZnO nanorods (ZnO-NRs) and two dimensional nanoflakes (ZnO-NFs) as immobilizing matrix. The synthesized ZnO nanostructures (NSs) were characterized using scanning electron microscopy (SEM), selective area diffraction (SAED) and photoluminescence spectra (PL) which showed that both ZnO-NRs and ZnO-NFs are single crystalline and oriented in [0001] direction. Anti-cortisol antibody (Anti-Cab) are used as primary capture antibodies to detect cortisol using electrochemical impedance spectroscopy (EIS). The charge transfer resistance increases linearly with increase in cortisol concentration and exhibits a sensitivity of 3.078 KΩ. M-1 for ZnO-NRs and 540 Ω. M -1 for ZnO-NFs. The developed ZnO-NSs based immunosensor is capable of detecting cortisol at 1 pM. The observed sensing parameters are in physiological range. The developed sensors can be integrated with microfluidic system and miniaturized potentiostat to detect cortisol at point-of-care.

  2. Confocal Raman Microscopy

    CERN Document Server

    Dieing, Thomas; Toporski, Jan

    2011-01-01

    Confocal Raman Microscopy is a relatively new technique that allows chemical imaging without specific sample preparation. By integrating a sensitive Raman spectrometer within a state-of-the-art microscope, Raman microscopy with a spatial resolution down to 200nm laterally and 500nm vertically can be achieved using visible light excitation. Recent developments in detector and computer technology as well as optimized instrument design have reduced integration times of Raman spectra by orders of magnitude, so that complete images consisting of tens of thousands of Raman spectra can be acquired in seconds or minutes rather than hours, which used to be standard just one decade ago. The purpose of this book is to provide the reader a comprehensive overview of the rapidly developing field of Confocal Raman Microscopy and its applications.

  3. Confocal scanning microscopy

    DEFF Research Database (Denmark)

    Bariani, Paolo

    This report is based on a metrological investigation on confocal microscopy technique carried out by Uffe Rolf Arlø Theilade and Paolo Bariani. The purpose of the experimental activity was twofold a metrological instrument characterization and application to assessment of rough PP injection moulded...... replicated topography. Confocal microscopy is seen to be a promising technique in metrology of microstructures. Some limitations with respect to surface metrology were found during the experiments. The experiments were carried out using a Zeiss LSM 5 Pascal microscope owned by the Danish Polymer Centre...

  4. Leakage radiation interference microscopy.

    Science.gov (United States)

    Descrovi, Emiliano; Barakat, Elsie; Angelini, Angelo; Munzert, Peter; De Leo, Natascia; Boarino, Luca; Giorgis, Fabrizio; Herzig, Hans Peter

    2013-09-01

    We present a proof of principle for a new imaging technique combining leakage radiation microscopy with high-resolution interference microscopy. By using oil immersion optics it is demonstrated that amplitude and phase can be retrieved from optical fields, which are evanescent in air. This technique is illustratively applied for mapping a surface mode propagating onto a planar dielectric multilayer on a thin glass substrate. The surface mode propagation constant estimated after Fourier transformation of the measured complex field is well matched with an independent measurement based on back focal plane imaging.

  5. Electrochemical hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Digby Macdonald

    2010-08-09

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not

  6. Electrochemical hydrogen Storage Systems

    International Nuclear Information System (INIS)

    Macdonald, Digby

    2010-01-01

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not described in the

  7. Electrochemical extraction of samarium from molten chlorides in pyrochemical processes

    International Nuclear Information System (INIS)

    Castrillejo, Y.; Fernandez, P.; Medina, J.; Hernandez, P.; Barrado, E.

    2011-01-01

    This work concerns the electrochemical extraction of samarium from molten chlorides. In this way, the electrochemical behaviour of samarium ions has been investigated in the eutectic LiCl-KCl at the surface of tungsten, aluminium and aluminium coated tungsten electrodes. On a W inert electrode the electro-reduction of Sm(III) takes place in only one soluble-soluble electrochemical step Sm(III)/Sm(II). The electrochemical system Sm(II)/Sm(0) has not been observed within the electrochemical window, because of the prior reduction of Li(I) ions from the solvent, which inhibits the electro-extraction of Sm species from the salt on such a substrate. Sm metal in contact with the melt react to give Li(0) according to the reaction: Sm(0) + 2Li(I) ↔ Sm(II) + 2Li(0). On the contrary, on reactive Al electrodes the electrochemical system Sm(II)/Sm(0) was observed within the electroactive range. The potential shift of the redox couple is caused by the decrease of Sm activity in the metal phase due to the formation of Sm-Al alloys at the interface. The formation mechanism of the intermetallic compounds was studied in a melt containing: (i) both Sm(III) and Al(III) ions, using W and Al coated tungsten electrodes, and (ii) Sm(III) ions using an Al electrode. Analysis of the samples after potentiostatic electrolysis by X-ray diffraction and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), allowed the identification of Al 3 Sm and Al 2 Sm.

  8. Electrochemical extraction of samarium from molten chlorides in pyrochemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Castrillejo, Y., E-mail: ycastril@qa.uva.es [QUIANE/Dept Quimica Analitica, F. de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain); Fernandez, P. [QUIANE/Dept Quimica Analitica, F. de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain); Medina, J. [Dept Fisica Materia Condensada Cristalografia y Mineralogia, F. de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain); Hernandez, P. [Centro de Investigaciones Quimicas, Universidad Autonoma del Estado de Hidalgo, Carr. Pachuca-Tulancingo Km. 4.5, C.P. 42076 Pachuca, Hidalgo (Mexico); Barrado, E. [QUIANE/Dept Quimica Analitica, F. de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain)

    2011-10-01

    This work concerns the electrochemical extraction of samarium from molten chlorides. In this way, the electrochemical behaviour of samarium ions has been investigated in the eutectic LiCl-KCl at the surface of tungsten, aluminium and aluminium coated tungsten electrodes. On a W inert electrode the electro-reduction of Sm(III) takes place in only one soluble-soluble electrochemical step Sm(III)/Sm(II). The electrochemical system Sm(II)/Sm(0) has not been observed within the electrochemical window, because of the prior reduction of Li(I) ions from the solvent, which inhibits the electro-extraction of Sm species from the salt on such a substrate. Sm metal in contact with the melt react to give Li(0) according to the reaction: Sm(0) + 2Li(I) {r_reversible} Sm(II) + 2Li(0). On the contrary, on reactive Al electrodes the electrochemical system Sm(II)/Sm(0) was observed within the electroactive range. The potential shift of the redox couple is caused by the decrease of Sm activity in the metal phase due to the formation of Sm-Al alloys at the interface. The formation mechanism of the intermetallic compounds was studied in a melt containing: (i) both Sm(III) and Al(III) ions, using W and Al coated tungsten electrodes, and (ii) Sm(III) ions using an Al electrode. Analysis of the samples after potentiostatic electrolysis by X-ray diffraction and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), allowed the identification of Al{sub 3}Sm and Al{sub 2}Sm.

  9. Fluorescence confocal polarizing microscopy

    Indian Academy of Sciences (India)

    Much of the modern understanding of orientational order in liquid crystals (LCs) is based on polarizing microscopy (PM). A PM image bears only two-dimensional (2D) information, integrating the 3D pattern of optical birefringence over the path of light. Recently, we proposed a technique to image 3D director patterns by ...

  10. Ballistic hole magnetic microscopy

    NARCIS (Netherlands)

    Haq, E.; Banerjee, T.; Siekman, M.H.; Lodder, J.C.; Jansen, R.

    2005-01-01

    A technique to study nanoscale spin transport of holes is presented: ballistic hole magnetic microscopy. The tip of a scanning tunneling microscope is used to inject hot electrons into a ferromagnetic heterostructure, where inelastic decay creates a distribution of electron-hole pairs.

  11. Acoustic, electrochemical and microscopic characterization of interaction of Arthrospira platensis biofilm and heavy metal ions

    OpenAIRE

    Tekaya , Nadèje; Gammoudi , Ibtissèm; Braiek , Mohamed; Tarbague , Hakim; Morote , Fabien; Raimbault , Vincent; Sakly , Nawfel; Rebière , Dominique; Ben Ouada , Hatem; Lagarde , Florence; Ben Ouada , Hafedh; Cohen-Bouhacina , Touria; Déjous , Corinne; Jaffrezic-Renault , Nicole

    2013-01-01

    International audience; This study examines a biofilm of Arthrospira platensis and its interactions with cadmium and mercury, using electrochemical admittance spectroscopy technique combined with highly sensitive Love wave platform for the real-time detection in liquid medium. Spirulina cells were immobilized via multilayers of polyelectrolyte (PEM) on Si/SiO2 surface of both transducers and characterized using atomic force microscopy (AFM). Scanning electron microscopy (SEM) cell images reve...

  12. Electrochemical treatment of graphite

    Energy Technology Data Exchange (ETDEWEB)

    Podlovilin, V.I.; Egorov, I.M.; Zhernovoj, A.I.

    1983-01-01

    In the course of investigating various modes of electrochemical treatment (ECT) it has been found that graphite anode treatment begins under the ''glow mode''. A behaviour of some marks of graphite with the purpose of ECT technique development in different electrolytes has been tested. Electrolytes have been chosen of three types: highly alkaline (pH 13-14), neutral (pH-Z) and highly acidic (pH 1-2). For the first time parallel to mechanical electroerosion treatment, ECT of graphite and carbon graphite materials previously considered chemically neutral is proposed. ECT of carbon graphite materials has a number of advantages as compared with electroerrosion and mechanical ones with respect to the treatment rate and purity (ronghness) of the surface. A small quantity of sludge (6-8%) under ECT is in highly alkali electrolytes.

  13. Organic electrochemical transistors

    Science.gov (United States)

    Rivnay, Jonathan; Inal, Sahika; Salleo, Alberto; Owens, Róisín M.; Berggren, Magnus; Malliaras, George G.

    2018-02-01

    Organic electrochemical transistors (OECTs) make effective use of ion injection from an electrolyte to modulate the bulk conductivity of an organic semiconductor channel. The coupling between ionic and electronic charges within the entire volume of the channel endows OECTs with high transconductance compared with that of field-effect transistors, but also limits their response time. The synthetic tunability, facile deposition and biocompatibility of organic materials make OECTs particularly suitable for applications in biological interfacing, printed logic circuitry and neuromorphic devices. In this Review, we discuss the physics and the mechanism of operation of OECTs, focusing on their identifying characteristics. We highlight organic materials that are currently being used in OECTs and survey the history of OECT technology. In addition, form factors, fabrication technologies and applications such as bioelectronics, circuits and memory devices are examined. Finally, we take a critical look at the future of OECT research and development.

  14. Electrochemical Hydrogen Compressor

    Energy Technology Data Exchange (ETDEWEB)

    Lipp, Ludwig [FuelCell Energy, Inc., Torrington, CT (United States)

    2016-01-21

    Conventional compressors have not been able to meet DOE targets for hydrogen refueling stations. They suffer from high capital cost, poor reliability and pose a risk of fuel contamination from lubricant oils. This project has significantly advanced the development of solid state hydrogen compressor technology for multiple applications. The project has achieved all of its major objectives. It has demonstrated capability of Electrochemical Hydrogen Compression (EHC) technology to potentially meet the DOE targets for small compressors for refueling sites. It has quantified EHC cell performance and durability, including single stage hydrogen compression from near-atmospheric pressure to 12,800 psi and operation of EHC for more than 22,000 hours. Capital cost of EHC was reduced by 60%, enabling a path to meeting the DOE cost targets for hydrogen compression, storage and delivery ($2.00-2.15/gge by 2020).

  15. Fast electrochemical actuator

    International Nuclear Information System (INIS)

    Uvarov, I V; Postnikov, A V; Svetovoy, V B

    2016-01-01

    Lack of fast and strong microactuators is a well-recognized problem in MEMS community. Electrochemical actuators can develop high pressure but they are notoriously slow. Water electrolysis produced by short voltage pulses of alternating polarity can overcome the problem of slow gas termination. Here we demonstrate an actuation regime, for which the gas pressure is relaxed just for 10 μs or so. The actuator consists of a microchamber filled with the electrolyte and covered with a flexible membrane. The membrane bends outward when the pressure in the chamber increases. Fast termination of gas and high pressure developed in the chamber are related to a high density of nanobubbles in the chamber. The physical processes happening in the chamber are discussed so as problems that have to be resolved for practical applications of this actuation regime. The actuator can be used as a driving engine for microfluidics. (paper)

  16. Organic electrochemical transistors

    KAUST Repository

    Rivnay, Jonathan

    2018-01-16

    Organic electrochemical transistors (OECTs) make effective use of ion injection from an electrolyte to modulate the bulk conductivity of an organic semiconductor channel. The coupling between ionic and electronic charges within the entire volume of the channel endows OECTs with high transconductance compared with that of field-effect transistors, but also limits their response time. The synthetic tunability, facile deposition and biocompatibility of organic materials make OECTs particularly suitable for applications in biological interfacing, printed logic circuitry and neuromorphic devices. In this Review, we discuss the physics and the mechanism of operation of OECTs, focusing on their identifying characteristics. We highlight organic materials that are currently being used in OECTs and survey the history of OECT technology. In addition, form factors, fabrication technologies and applications such as bioelectronics, circuits and memory devices are examined. Finally, we take a critical look at the future of OECT research and development.

  17. Advanced Microscopy of Microbial Cells

    DEFF Research Database (Denmark)

    Haagensen, Janus Anders Juul; Regenberg, Birgitte; Sternberg, Claus

    2011-01-01

    microscopy, super-resolution optical microscopy (STED, SIM, PALM) as well as atomic force microscopy and Raman spectroscopy. Using examples of bistability in microbial populations as well as biofilm development and differentiation in bacterial and yeast consortia, we demonstrate the importance of microscopy...

  18. Static and Dynamic Measurement of Dopamine Adsorption in Carbon Fiber Microelectrodes Using Electrochemical Impedance Spectroscopy.

    Science.gov (United States)

    Rivera-Serrano, Nilka; Pagan, Miraida; Colón-Rodríguez, Joanisse; Fuster, Christian; Vélez, Román; Almodovar-Faria, Jose; Jiménez-Rivera, Carlos; Cunci, Lisandro

    2018-02-06

    In this study, electrochemical impedance spectroscopy was used for the first time to study the adsorption of dopamine in carbon fiber microelectrodes. In order to show a proof-of-concept, static and dynamic measurements were taken at potentials ranging from -0.4 to 0.8 V versus Ag|AgCl to demonstrate the versatility of this technique to study dopamine without the need of its oxidation. We used electrochemical impedance spectroscopy and single frequency electrochemical impedance to measure different concentrations of dopamine as low as 1 nM. Moreover, the capacitance of the microelectrodes surface was found to decrease due to dopamine adsorption, which is dependent on its concentration. The effect of dissolved oxygen and electrochemical oxidation of the surface in the detection of dopamine was also studied. Nonoxidized and oxidized carbon fiber microelectrodes were prepared and characterized by optical microscopy, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Optimum working parameters of the electrodes, such as frequency and voltage, were obtained for better measurement. Electrochemical impedance of dopamine was determined at different concentration, voltages, and frequencies. Finally, dynamic experiments were conducted using a flow cell and single frequency impedance in order to study continuous and real-time measurements of dopamine.

  19. Polarized Light Microscopy

    Science.gov (United States)

    Frandsen, Athela F.

    2016-01-01

    Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often

  20. Multifunctional Graphene-based Hybrid Nanomaterials for Electrochemical Energy Storage.

    Science.gov (United States)

    Gupta, Sanju

    Intense research in renewable energy is stimulated by global demand of electric energy. Electrochemical energy storage and conversion systems namely, supercapacitors and batteries, represent the most efficient and environmentally benign technologies. Moreover, controlled nanoscaled architectures and surface chemistry of electrochemical electrodes is enabling emergent next-generation efficient devices approaching theoretical limit of energy and power densities. This talk will present our recent activities to advance design, development and deployment of composition, morphology and microstructure controlled two- and three-dimensional graphene-based hybrids architectures. They are chemically and molecularly bridged with carbon nanotubes, conducting polymers, transition metal oxides and mesoproprous silicon wrapped with graphene nanosheets as engineered electrodes for supercapacitor cathodes and battery anodes. They showed significant enhancement in terms of gravimetric specific capacitance, interfacial capacitance, charging-discharging rate and cyclability. We will also present fundamental physical-chemical interfacial processes (ion transfer kinetics and diffusion), imaging electroactive sites, and topography at electrode/electrolyte interface governing underlying electrochemical mechanisms via scanning electrochemical microscopy. KY NSF EPSCoR.

  1. Surface modification and electrochemical behaviour of undoped nanodiamonds

    International Nuclear Information System (INIS)

    Zang Jianbing; Wang Yanhui; Bian Linyan; Zhang Jinhui; Meng Fanwei; Zhao Yuling; Ren Shubin; Qu Xuanhui

    2012-01-01

    Surface modifications of undoped nanodiamond (ND) particles were carried out through different annealing treatments. The methods of Fourier transform infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy were used to characterize the ND surface before and after the annealing process. The electrochemical properties of the modified ND powders in aqueous solution were investigated with Fe(CN) 6 3−/4− as a redox probe. When the annealing temperature was below 850 °C, vacuum annealing removed parts of the oxygen-containing surface functionalities from the ND surface and produced more sp 2 carbon atoms in the shell. The charge transfer of the Fe(CN) 6 3−/4− redox couple decreased with increasing annealing temperature. Re-annealing in air restored the original surface conditions: few sp 2 -bonded carbon atoms and similar surface functionalities, and thus the electrochemical activity. When ND was annealed in vacuum at 900–1100 °C, more serious graphitization produced a continuous fullerenic shell wrapped around a diamond core, which had a high conductivity and electrochemical activity. This provides a novel nanoparticle with high conductivity and high stability for electrochemical applications.

  2. Ultra-nanocrystalline diamond nanowires with enhanced electrochemical properties

    International Nuclear Information System (INIS)

    Shalini, Jayakumar; Lin, Yi-Chieh; Chang, Ting-Hsun; Sankaran, Kamatchi Jothiramalingam; Chen, Huang-Chin; Lin, I.-Nan; Lee, Chi-Young; Tai, Nyan-Hwa

    2013-01-01

    The effects of N 2 incorporation in Ar/CH 4 plasma on the electrochemical properties and microstructure of ultra-nanocrystalline diamond (UNCD) films are reported. While the electrical conductivity of the films increased monotonously with increasing N 2 content (up to 25%) in the plasma, the electrochemical behavior was optimized for UNCD films grown in (Ar–10% N 2 )/CH 4 plasma. Transmission electron microscopy showed that the main factor resulting in high conductivity in the films was the formation of needle-like nanodiamond grains and the induction graphite layer encapsulating these grains. The electrochemical process for N 2 -incorporated UNCD films can readily be activated due to the presence of nanographite along the grain boundaries of the films. The formation of needle-like diamond grains was presumably due to the presence of CN species that adhered to the existing nanodiamond clusters, which suppressed radial growth of the nanodiamond crystals, promoting anisotropic growth and the formation of needle-like nanodiamond. The N 2 -incorporated UNCD films outperformed other electrochemical electrode materials, such as boron-doped diamond and glassy carbon, in that the UNCD electrodes could sense dopamine, urea, and ascorbic acid simultaneously in the same mixture with clear resolution

  3. Spectroscopic and electrochemical characterization of nanostructured optically transparent carbon electrodes.

    Science.gov (United States)

    Benavidez, Tomás E; Garcia, Carlos D

    2013-07-01

    The present paper describes the results related to the optical and electrochemical characterization of thin carbon films fabricated by spin coating and pyrolysis of AZ P4330-RS photoresist. The goal of this paper is to provide comprehensive information allowing for the rational selection of the conditions to fabricate optically transparent carbon electrodes (OTCE) with specific electrooptical properties. According to our results, these electrodes could be appropriate choices as electrochemical transducers to monitor electrophoretic separations. At the core of this manuscript is the development and critical evaluation of a new optical model to calculate the thickness of the OTCE by variable angle spectroscopic ellipsometry. Such data were complemented with topography and roughness (obtained by atomic force microscopy), electrochemical properties (obtained by cyclic voltammetry), electrical properties (obtained by electrochemical impedance spectroscopy), and structural composition (obtained by Raman spectroscopy). Although the described OTCE were used as substrates to investigate the effect of electrode potential on the real-time adsorption of proteins by ellipsometry, these results could enable the development of other biosensors that can be then integrated into various CE platforms. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Chemical splitting of multiwalled carbon nanotubes to enhance electrochemical capacitance for supercapacitors

    Science.gov (United States)

    Li, Xinlu; Li, Tongtao; Zhang, Xinlin; Zhong, Qineng; Li, Hongyi; Huang, Jiamu

    2014-06-01

    Multiwalled carbon nanotubes (MWCNTs) were chemically split and self-assembled to a flexible porous paper made of graphene oxide nanoribbons (GONRs). The morphology and microstructure of the pristine MWCNTs and GONRs were analyzed by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy. And the specific surface area and porosity structure were measured by N2 adsorption-desorption. The longitudinally split MWCNTs show an enhancement in specific capacitance from 21 F g-1 to 156 F g-1 compared with the pristine counterpart at 0.1 A g-1 in a 6 M KOH aqueous electrolytes. The electrochemical experiments prove that the chemical splitting of MWCNTs will make inner carbon layers opened and exposed to electrochemical double layers, which can effectively improve the electrochemical capacitance for supercapacitors.

  5. Characterization of immobilization methods of antiviral antibodies in serum for electrochemical biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Huy, Tran Quang, E-mail: huytq@nihe.org.vn [National Institute of Hygiene and Epidemiology (NIHE), No1 Yersin St., Hanoi (Viet Nam); International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), No1 Dai Co Viet, Hanoi (Viet Nam); Hanh, Nguyen Thi Hong; Van Chung, Pham; Anh, Dang Duc; Nga, Phan Thi [National Institute of Hygiene and Epidemiology (NIHE), No1 Yersin St., Hanoi (Viet Nam); Tuan, Mai Anh, E-mail: tuanma-itims@mail.hut.edu.vn [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), No1 Dai Co Viet, Hanoi (Viet Nam)

    2011-06-01

    In this paper, we describes different methods to immobilize Japanese encephalitis virus (JEV) antibodies in human serum onto the interdigitated surface of a microelectrode sensor for optimizing electrochemical detection: (1) direct covalent binding to the silanized surface, (2) binding to the silanized surface via a cross-linker of glutaraldehyde (GA), (3) binding to glutaraldehyde/silanized surface via goat anti-human IgG polyclonal antibody and (4) binding to glutaraldehyde/silanized surface via protein A (PrA). Field emission scanning electron microscopy, Fourier transform infrared spectrometry, and fluorescence microscopy are used to verify the characteristics of antibodies on the interdigitated surface after the serum antibodies immobilization. The analyzed results indicate that the use of protein A is an effective choice for immobilization and orientation of antibodies in serum for electrochemical biosensors. This study provides an advantageous immobilization method of serum containing antiviral antibodies to develop electrochemical biosensors for preliminary screening of viruses in clinical samples from outbreaks.

  6. Electrochemical applications of CVD diamond

    International Nuclear Information System (INIS)

    Pastor-Moreno, Gustavo

    2002-01-01

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

  7. Electron microscopy in metallurgy

    International Nuclear Information System (INIS)

    Loretto, M.H.

    1980-01-01

    The aim of this paper is to review briefly the contribution which (TEM) transmission electron microscopy (including high voltage electron microscopy (HVEM)) has made to metallurgy. Since it is straightforward with modern electron microscopes to extract the crystallographic information which provides the basis for any interpretation, the major problem in most metallurgical work lies in assessing how the structure (which TEM has characterised) has arisen and which properties of the specimen can be understood in terms of this structure. Radiation damage, quenching, phase transformations, grain boundaries and plastic deformation have been the main fields in which TEM has contributed significantly. After briefly summarising the role of TEM in each field, examples of recent work will be used to indicate current TEM activity in physical metallurgy. (author)

  8. Second harmonic generation microscopy

    DEFF Research Database (Denmark)

    Brüggemann, Dagmar Adeline; Brewer, Jonathan R.; Risbo, Jens

    2010-01-01

    Myofibers and collagen show non-linear optical properties enabling imaging using second harmonic generation (SHG) microscopy. The technique is evaluated for use as a tool for real-time studies of thermally induced changes in thin samples of unfixed and unstained pork. The forward and the backward...... scattered SHG light reveal complementary features of the structures of myofibers and collagen fibers. Upon heating the myofibers show no structural changes before reaching a temperature of 53 °C. At this temperature the SHG signal becomes extinct. The extinction of the SHG at 53 °C coincides with a low......-temperature endotherm peak observable in the differential scanning calorimetry (DSC) thermograms. DSC analysis of epimysium, the connective tissue layer that enfold skeletal muscles, produces one large endotherm starting at 57 °C and peaking at 59.5 °C. SHG microscopy of collagen fibers reveals a variability of thermal...

  9. Sensitive Electrochemical Detection of Native and Aggregated x-Synuclein Protein Involved in Parkinson's Disease

    NARCIS (Netherlands)

    Masarik, Michal; Stobiecka, Agata; Kizek, René; Jelen, Frantisek; Pechan, Zdenk; Hoyer, Wolfgang; Subramaniam, Vinod; Palecek, Emil

    2004-01-01

    The aggregation of α-synuclein, a 14 kDa protein, is involved in several human neurodegenerative disorders, including Parkinson's disease. We studied native and in vitro aggregated α-synuclein by circular dichroism (CD), atomic force microscopy (AFM) and electrochemical methods. We used constant

  10. Electron microscopy and diffraction

    International Nuclear Information System (INIS)

    Gjoennes, J.; Olsen, A.

    1986-01-01

    This report is a description of research activities and plans at the electron microscopy laboratorium, Physics Department, University of Oslo. Since the first electron microscope was installed in 1968, the research has covered inorganic structures, physical metallurgy, as well as theory of electron scattering and the development of methods in this field. The current plans involve efforts in the development of crystallographic and spectroscopic methods

  11. Influence of the polymeric coating thickness on the electrochemical performance of Carbon Fiber/PAni composites

    Directory of Open Access Journals (Sweden)

    Carla Polo Fonseca

    2015-10-01

    Full Text Available Abstract Carbon fiber/polyaniline composites (CF/PAni were synthesized at three different deposition time of 30, 60 and 90 min by oxidative polymerization. The composite materials were morphologically and physically characterized by scanning electron microscopy and by Raman spectroscopy, respectively. Their electrochemical responses were analyzed by cyclic voltammetry, by galvanostatic test, and by electrochemical impedance spectroscopy. The influence of the PAni layer thickness deposited on carbon fibers for the composite formation as well as for their electrochemical properties was discussed. The CF/PAni-30 showed a nanometric thickness with more homogeneous morphology compared to those formed in deposition times of 60 and 90 min. It also showed, from the electrochemical impedance spectroscopy measurements, the lowest charge transfer resistance value associated to the its highest value for the double-layer capacitance of 180 Fg-1 making it a very strong candidate as a supercapacitor electrode.

  12. Water-mediated electrochemical nano-writing on thin ceria films

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  13. Deep Learning Microscopy

    KAUST Repository

    Rivenson, Yair

    2017-05-12

    We demonstrate that a deep neural network can significantly improve optical microscopy, enhancing its spatial resolution over a large field-of-view and depth-of-field. After its training, the only input to this network is an image acquired using a regular optical microscope, without any changes to its design. We blindly tested this deep learning approach using various tissue samples that are imaged with low-resolution and wide-field systems, where the network rapidly outputs an image with remarkably better resolution, matching the performance of higher numerical aperture lenses, also significantly surpassing their limited field-of-view and depth-of-field. These results are transformative for various fields that use microscopy tools, including e.g., life sciences, where optical microscopy is considered as one of the most widely used and deployed techniques. Beyond such applications, our presented approach is broadly applicable to other imaging modalities, also spanning different parts of the electromagnetic spectrum, and can be used to design computational imagers that get better and better as they continue to image specimen and establish new transformations among different modes of imaging.

  14. Surface x-ray scattering and scanning tunneling microscopy studies at the Au(111) electrode

    International Nuclear Information System (INIS)

    Ocko, B.M.; Magnussen, O.M.; Wang, J.X.; Adzic, R.R.

    1993-01-01

    This chapter reviews Surface X-ray Scattering and Scanning Tunneling Microscopy results carried out at the Au(111) surface under electrochemical conditions. Results are presented for the reconstructed surface, and for bromide and thallium monolayers. These examples are used to illustrate the complementary nature of the techniques

  15. Characterization of Electrochemically Generated Silver

    Science.gov (United States)

    Adam, Niklas; Martinez, James; Carrier, Chris

    2014-01-01

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

  16. Electrochemical incineration of wastes

    Science.gov (United States)

    Kaba, L.; Hitchens, G. D.; Bockris, J. OM.

    1989-01-01

    The disposal of domestic organic waste in its raw state is a matter of increasing public concern. Earlier, it was regarded as permissible to reject wastes into the apparently infinite sink of the sea but, during the last 20 years, it has become clear that this is environmentally unacceptable. On the other hand, sewage farms and drainage systems for cities and for new housing developments are cumbersome and expensive to build and operate. New technology whereby waste is converted to acceptable chemicals and pollution-free gases at site is desirable. The problems posed by wastes are particularly demanding in space vehicles where it is desirable to utilize treatments that will convert wastes into chemicals that can be recycled. In this situation, the combustion of waste is undesirable due to the inevitable presence of oxides of nitrogen and carbon monoxide in the effluent gases. Here, in particular, electrochemical techniques offer several advantages including the low temperatures which may be used and the absence of any NO and CO in the evolved gases. Work done in this area was restricted to technological papers, and the present report is an attempt to give a more fundamental basis to the early stages of a potentially valuable technology.

  17. Electrochemically cathodic exfoliation of graphene sheets in room temperature ionic liquids N-butyl, methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and their electrochemical properties

    International Nuclear Information System (INIS)

    Yang, Yingchang; Lu, Fang; Zhou, Zhou; Song, Weixin; Chen, Qiyuan; Ji, Xiaobo

    2013-01-01

    Graphical abstract: Electrochemically cathodic exfoliation of graphite into few-layer graphene sheets in room temperature ionic liquids (RTILs) N-butyl, methylpyrrolidinium bis(trifluoromethylsulfonyl)-imide (BMPTF 2 N). -- Highlights: • Few-layer graphene sheets were prepared through electrochemically cathodic exfoliation in room temperature ionic liquids. • The mechanism of cathodic exfoliation in ionic liquids was proposed. • The derived activated graphene sheets show enhanced electrochemical properties. -- Abstract: Electrochemically cathodic exfoliation in room temperature ionic liquids N-butyl, methylpyrrolidinium bis(trifluoromethylsulfonyl)-imide (BMPTF 2 N) has been developed for few-layer graphene sheets, demonstrating low levels of oxygen (2.7 at% of O) with a nearly perfect structure (I D /I G 2 N involves the intercalation of ionic liquids cation [BMP] + under highly negatively charge followed by graphite expansion. Porous activated graphene sheets were also obtained by activation of graphene sheets in KOH. Transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy were used to characterize these graphene materials. The electrochemical performances of the graphene sheets and porous activated graphene sheets for lithium-ion battery anode materials were evaluated using cyclic voltammetry, galvanostatic charge–discharge cycling, and electrochemical impedance spectroscopy

  18. Fourier plane imaging microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez, Daniel, E-mail: daniel.dominguez@ttu.edu; Peralta, Luis Grave de [Department of Physics, Texas Tech University, Lubbock, Texas 79409 (United States); Nano Tech Center, Texas Tech University, Lubbock, Texas 79409 (United States); Alharbi, Nouf; Alhusain, Mdhaoui [Department of Physics, Texas Tech University, Lubbock, Texas 79409 (United States); Bernussi, Ayrton A. [Nano Tech Center, Texas Tech University, Lubbock, Texas 79409 (United States); Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States)

    2014-09-14

    We show how the image of an unresolved photonic crystal can be reconstructed using a single Fourier plane (FP) image obtained with a second camera that was added to a traditional compound microscope. We discuss how Fourier plane imaging microscopy is an application of a remarkable property of the obtained FP images: they contain more information about the photonic crystals than the images recorded by the camera commonly placed at the real plane of the microscope. We argue that the experimental results support the hypothesis that surface waves, contributing to enhanced resolution abilities, were optically excited in the studied photonic crystals.

  19. Addition of nitrite enhances the electrochemical defluorination of 2-fluoroaniline

    International Nuclear Information System (INIS)

    Feng, Huajun; Liang, Yuxiang; Guo, Kun; Long, Yuyang; Cong, Yanqing; Shen, Dongsheng

    2015-01-01

    Highlights: • A method for improving defluorination performance by in situ self-assembly of pollutants was developed. • The mechanisms of 2-FA modification and defluorination are discussed. • Positively-charged diazonium salt is used to weaken the C–F bond. - Abstract: This study introduces a novel approach that uses the interaction of pollutants with added nitrite to produce diazonium salts, which cause in situ self-assembly of the pollutants on carbon electrodes, to improve their 2-fluoroaniline (2-FA) defluorination and removal performance. The 2-FA degradation performance, electrode properties, electrochemical properties and degradation pathway were investigated. The reactor containing NO_2"− achieved a 2-FA removal efficiency of 90.1% and a defluorination efficiency of 38% within 48 h, 1.4 and 2.3 times higher than the corresponding results achieved without NO_2"−, respectively. The residual NO_2"− was less than 0.5 mg/L in the reactor containing added NO_2"−, which would not cause serious secondary pollution. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) results proved that the carbon anode surface was successfully modified with benzene polymer, and electrochemical tests confirmed that the electrochemical activity of the modified anode was enhanced significantly. The C–F bond was weakened by the effect of the positive charge of the benzenediazonium groups, and the high electrochemical activity of the carbon anode enhanced the electrochemical performance of the system to accelerate defluorination. Thus, the present electrical method involving nitrite nitrogen is very promising for the treatment of wastewater containing fluoroaniline compounds.

  20. Electrochemical capacitor behavior of copper sulfide (CuS) nanoplatelets

    Energy Technology Data Exchange (ETDEWEB)

    Justin Raj, C.; Kim, Byung Chul; Cho, Won-Je; Lee, Won-Gil; Seo, Yongseong; Yu, Kook-Hyun, E-mail: yukook@dongguk.edu

    2014-02-15

    Highlights: • The electrochemical supercapacitor electrode was fabricated using CuS nanoplatelets. • CuS electrodes shows better electrochemical properties in aqueous LiClO{sub 4} electrolyte. • The heat treated CuS electrode shows an excellent pseudocapacitance performance than bare CuS electrode. -- Abstract: Copper sulfide (CuS) nanoplatelets have been fabricated by simple low temperature chemical bath deposition technique for electrochemical supercapacitor electrodes. The morphology and structural properties of the electrodes were analyzed using scanning electron microscopy and X-ray diffraction. The effect of heat treatment on electrochemical properties of CuS electrodes were examined by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge tests. Results show that bare and heat treated CuS has pseudocapacitive characteristic within the potential range of −0.6 to 0.3 V (vs. Ag/AgCl) in aqueous 1 M LiClO{sub 4} solution. The pseudocapacitance is induced mainly by lithium ions insertion/extraction with the CuS electrodes. The specific capacitance of 72.85 F g{sup −1} was delivered by heat treated CuS film at a scan rate of 5 mV s{sup −1} with an energy and power density of 6.23 W h kg{sup −1} and 1.75 kW kg{sup −1} at 3 Ag{sup −1} constant discharge current which is comparatively higher than that of as deposited CuS electrode.

  1. Addition of nitrite enhances the electrochemical defluorination of 2-fluoroaniline

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Huajun [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012 (China); Laboratory of Microbial Ecology and Technology, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Liang, Yuxiang [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012 (China); Guo, Kun [Laboratory of Microbial Ecology and Technology, Ghent University, Coupure Links 653, B-9000 Ghent (Belgium); Long, Yuyang [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012 (China); Cong, Yanqing, E-mail: yqcong@hotmail.com [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Shen, Dongsheng [School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310012 (China); Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou 310012 (China)

    2015-12-30

    Highlights: • A method for improving defluorination performance by in situ self-assembly of pollutants was developed. • The mechanisms of 2-FA modification and defluorination are discussed. • Positively-charged diazonium salt is used to weaken the C–F bond. - Abstract: This study introduces a novel approach that uses the interaction of pollutants with added nitrite to produce diazonium salts, which cause in situ self-assembly of the pollutants on carbon electrodes, to improve their 2-fluoroaniline (2-FA) defluorination and removal performance. The 2-FA degradation performance, electrode properties, electrochemical properties and degradation pathway were investigated. The reactor containing NO{sub 2}{sup −} achieved a 2-FA removal efficiency of 90.1% and a defluorination efficiency of 38% within 48 h, 1.4 and 2.3 times higher than the corresponding results achieved without NO{sub 2}{sup −}, respectively. The residual NO{sub 2}{sup −} was less than 0.5 mg/L in the reactor containing added NO{sub 2}{sup −}, which would not cause serious secondary pollution. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) results proved that the carbon anode surface was successfully modified with benzene polymer, and electrochemical tests confirmed that the electrochemical activity of the modified anode was enhanced significantly. The C–F bond was weakened by the effect of the positive charge of the benzenediazonium groups, and the high electrochemical activity of the carbon anode enhanced the electrochemical performance of the system to accelerate defluorination. Thus, the present electrical method involving nitrite nitrogen is very promising for the treatment of wastewater containing fluoroaniline compounds.

  2. Synthesis of binary bismuth-cadmium oxide nanorods with sensitive electrochemical sensing performance

    International Nuclear Information System (INIS)

    Wen, Yong; Pei, Lizhai; Wei, Tian

    2017-01-01

    Binary bismuth-cadmium oxide nanorods have been synthesized by a simple hydrothermal process without templates and additives. X-ray diffraction and high-resolution transmission electron microscopy reveal that the nanorods possess single crystalline tetragonal Bi 2 CdO 4 phase. Scanning electron microscopy and transmission electron microscopy images show that the length and diameter of the nanorods are 20-300 nm and 5-10 μm, respectively. The formation of the binary bismuth-cadmium oxide nanorods is closely related to the hydrothermal parameters. The electrochemical sensing performance of the binary bismuth-cadmium oxide nanorods has been investigated using the nanorods as glassy carbon electrode modifiers. The detection limit is 0.19 μM with a linear range of 0.0005-2 mM. The nanorod-modified glassy carbon electrode exhibits good electrocatalytic activity toward L-cysteine and great application potential for electrochemical sensors.

  3. Synthesis of binary bismuth-cadmium oxide nanorods with sensitive electrochemical sensing performance

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Yong [Xinjiang Univ., Xinjiang (China). School of Civil Engineering and Architecture; Pei, Lizhai; Wei, Tian [Anhui Univ. of Technology, Anhui (China). School of Materials Science and Engineering

    2017-07-15

    Binary bismuth-cadmium oxide nanorods have been synthesized by a simple hydrothermal process without templates and additives. X-ray diffraction and high-resolution transmission electron microscopy reveal that the nanorods possess single crystalline tetragonal Bi{sub 2}CdO{sub 4} phase. Scanning electron microscopy and transmission electron microscopy images show that the length and diameter of the nanorods are 20-300 nm and 5-10 μm, respectively. The formation of the binary bismuth-cadmium oxide nanorods is closely related to the hydrothermal parameters. The electrochemical sensing performance of the binary bismuth-cadmium oxide nanorods has been investigated using the nanorods as glassy carbon electrode modifiers. The detection limit is 0.19 μM with a linear range of 0.0005-2 mM. The nanorod-modified glassy carbon electrode exhibits good electrocatalytic activity toward L-cysteine and great application potential for electrochemical sensors.

  4. Correlative Stochastic Optical Reconstruction Microscopy and Electron Microscopy

    Science.gov (United States)

    Kim, Doory; Deerinck, Thomas J.; Sigal, Yaron M.; Babcock, Hazen P.; Ellisman, Mark H.; Zhuang, Xiaowei

    2015-01-01

    Correlative fluorescence light microscopy and electron microscopy allows the imaging of spatial distributions of specific biomolecules in the context of cellular ultrastructure. Recent development of super-resolution fluorescence microscopy allows the location of molecules to be determined with nanometer-scale spatial resolution. However, correlative super-resolution fluorescence microscopy and electron microscopy (EM) still remains challenging because the optimal specimen preparation and imaging conditions for super-resolution fluorescence microscopy and EM are often not compatible. Here, we have developed several experiment protocols for correlative stochastic optical reconstruction microscopy (STORM) and EM methods, both for un-embedded samples by applying EM-specific sample preparations after STORM imaging and for embedded and sectioned samples by optimizing the fluorescence under EM fixation, staining and embedding conditions. We demonstrated these methods using a variety of cellular targets. PMID:25874453

  5. Electrochemical oxidation of organic waste

    International Nuclear Information System (INIS)

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

    1990-01-01

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

  6. Electrochemical depth profiling of multilayer metallic structures: An aluminum brazing sheet

    International Nuclear Information System (INIS)

    Afshar, F. Norouzi; Ambat, R.; Kwakernaak, C.; Wit, J.H.W. de; Mol, J.M.C.; Terryn, H.

    2012-01-01

    Highlights: ► Localized electrochemical cell and glow discharge optical emission spectrometry were used. ► An electrochemical depth profile of an aluminum brazing sheet was obtained. ► The electrochemical responses were correlated to the microstructural features. - Abstract: Combinatory localized electrochemical cell and glow discharge optical emission spectrometry (GDOES) measurements were performed to obtain a thorough in depth electrochemical characterization of an aluminum brazing sheet. By defining electrochemical criteria i.e. breakdown potential, corrosion potential, cathodic and anodic reactivities, and tracking their changes as a function of depth, the evolution of electrochemical responses through out the material thickness were analyzed and correlated to the corresponding microstructural features. Polarization curves in 1 wt% NaCl solution at pH 2.8 were obtained at different depths from the surface using controlled sputtering in a glow discharge optical emission spectrometer as a sample preparation technique. The anodic and cathodic reactivity of the top surface areas were significantly higher than that of the bulk, thus indicating these areas to be more susceptible to localized attack. Consistent with this, optical microscopy and scanning electron microscope analysis revealed a relatively high density of fine intermetallic and silicon particles at these areas. The corrosion mechanism of the top layers was identified to be intergranular and pitting corrosion, while lower sensitivity to these localized attacks were detected toward the brazing sheet core. The results highlight the successful application of the electrochemical depth profiling approach in prediction of the corrosion behavior of the aluminum brazing sheet and the importance of the electrochemical activity of the outer 10 μm in controlling the corrosion performance of the aluminum brazing sheet.

  7. Enhanced optical performance of electrochemically etched porous silicon carbide

    International Nuclear Information System (INIS)

    Naderi, N; Hashim, M R; Saron, K M A; Rouhi, J

    2013-01-01

    Porous silicon carbide (PSC) was successfully synthesized via electrochemical etching of an n-type hexagonal silicon carbide (6H-SiC) substrate using various current densities. The cyclic voltammograms of SiC dissolution show that illumination is required for the accumulation of carriers at the surface, followed by surface oxidation and dissolution of the solid. The morphological and optical characterizations of PSC were reported. Scanning electron microscopy results demonstrated that the current density can be considered an important etching parameter that controls the porosity and uniformity of PSC; hence, it can be used to optimize the optical properties of the porous samples. (paper)

  8. Advanced Microscopy of Microbial Cells

    DEFF Research Database (Denmark)

    Haagensen, Janus Anders Juul; Regenberg, Birgitte; Sternberg, Claus

    2011-01-01

    Growing awareness of heterogeneity in cells of microbial populations has emphasized the importance of advanced microscopy for visualization and understanding of the molecular mechanisms underlying cell-to-cell variation. In this review, we highlight some of the recent advances in confocal...... microscopy, super-resolution optical microscopy (STED, SIM, PALM) as well as atomic force microscopy and Raman spectroscopy. Using examples of bistability in microbial populations as well as biofilm development and differentiation in bacterial and yeast consortia, we demonstrate the importance of microscopy...

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

    Science.gov (United States)

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

    2016-04-25

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

  10. Superhydrophobic surfaces by electrochemical processes.

    Science.gov (United States)

    Darmanin, Thierry; Taffin de Givenchy, Elisabeth; Amigoni, Sonia; Guittard, Frederic

    2013-03-13

    This review is an exhaustive representation of the electrochemical processes reported in the literature to produce superhydrophobic surfaces. Due to the intensive demand in the elaboration of superhydrophobic materials using low-cost, reproducible and fast methods, the use of strategies based on electrochemical processes have exponentially grown these last five years. These strategies are separated in two parts: the oxidation processes, such as oxidation of metals in solution, the anodization of metals or the electrodeposition of conducting polymers, and the reduction processed such as the electrodeposition of metals or the galvanic deposition. One of the main advantages of the electrochemical processes is the relative easiness to produce various surface morphologies and a precise control of the structures at a micro- or a nanoscale. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Hyperspectral light sheet microscopy

    Science.gov (United States)

    Jahr, Wiebke; Schmid, Benjamin; Schmied, Christopher; Fahrbach, Florian O.; Huisken, Jan

    2015-09-01

    To study the development and interactions of cells and tissues, multiple fluorescent markers need to be imaged efficiently in a single living organism. Instead of acquiring individual colours sequentially with filters, we created a platform based on line-scanning light sheet microscopy to record the entire spectrum for each pixel in a three-dimensional volume. We evaluated data sets with varying spectral sampling and determined the optimal channel width to be around 5 nm. With the help of these data sets, we show that our setup outperforms filter-based approaches with regard to image quality and discrimination of fluorophores. By spectral unmixing we resolved overlapping fluorophores with up to nanometre resolution and removed autofluorescence in zebrafish and fruit fly embryos.

  12. Highly sensitive electrochemical determination of Sunset Yellow based on gold nanoparticles/graphene electrode

    International Nuclear Information System (INIS)

    Wang, Jin; Yang, Beibei; Wang, Huiwen; Yang, Ping; Du, Yukou

    2015-01-01

    An electrochemical sensor was prepared using Au nanoparticles and reduced graphene successfully decorated on the glassy carbon electrode (Au/RGO/GCE) through an electrochemical method which was applied to detect Sunset Yellow (SY). The as-prepared electrode was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and electrochemical measurements. The results of cyclic voltammetry (CV) proved that Au/RGO/GCE had the highest catalytic activity for the oxidation of SY as compared with GCE, Au/GCE, and RGO/GCE. Differential pulse voltammetry (DPV) showed that the linear calibration curves for SY on Au/RGO/GCE in the range of 0.002 μM–109.14 μM, and the detection limit was estimated to be 2 nM (S/N = 3). These results suggested that the obtained Au/RGO/GCE was applied to detect SY with high sensitivity, low detection limit and good stability, which provided a promising future for the development of portable sensor in food additives. - Highlights: • An Au/RGO composite was fabricated by electrochemical deposition method. • The oxidation current of SY on the composition is up to 10 μA. • The detection range of SY is 0.002–109.14 μM with a detection limit of 2 nM.

  13. Progress in the Correlative Atomic Force Microscopy and Optical Microscopy

    Directory of Open Access Journals (Sweden)

    Lulu Zhou

    2017-04-01

    Full Text Available Atomic force microscopy (AFM has evolved from the originally morphological imaging technique to a powerful and multifunctional technique for manipulating and detecting the interactions between molecules at nanometer resolution. However, AFM cannot provide the precise information of synchronized molecular groups and has many shortcomings in the aspects of determining the mechanism of the interactions and the elaborate structure due to the limitations of the technology, itself, such as non-specificity and low imaging speed. To overcome the technical limitations, it is necessary to combine AFM with other complementary techniques, such as fluorescence microscopy. The combination of several complementary techniques in one instrument has increasingly become a vital approach to investigate the details of the interactions among molecules and molecular dynamics. In this review, we reported the principles of AFM and optical microscopy, such as confocal microscopy and single-molecule localization microscopy, and focused on the development and use of correlative AFM and optical microscopy.

  14. In situ electrochemical atomic force microscope study on graphite electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Hirasawa, K.A.; Sato, Tomohiro; Asahina, Hitoshi; Yamaguchi, Shoji; Mori, Shoichiro [Mitsubishi Chemical Corp., Inashiki, Ibaraki (Japan). Tsukuba Research Center

    1997-04-01

    Interest in the formation of the solid electrolyte interphase (SEI) film on graphite electrodes has increased recently in the quest to improve the performance of lithium-ion batteries. Topographic and frictional changes on the surface of a highly oriented pyrolytic graphite electrode in 1 M LiCiO{sub 4} ethylene carbonate/ethylmethyl carbonate (1:1) electrolyte were examined during charge and discharge by in situ electrochemical atomic force microscopy and friction force microscopy simultaneously in real-time. Solid electrolyte interphase film formation commenced at approximately 2 V vs. Li/Li{sup +} and stable film formation with an island-like morphology was observed below approximately 0.9 V vs. Li/Li{sup +}. Further experiments on a KS-44 graphite/polyvinylidene difluoride binder composite electrode showed similar phenomena.

  15. Electrochemical detection of ultratrace nitroaromatic explosives using ordered mesoporous carbon

    Energy Technology Data Exchange (ETDEWEB)

    Zang Jianfeng; Guo Chunxian; Hu Fengping [School of Chemical and Biomedical Engineering and Center for Advanced Bionanosystems, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457 (Singapore); Yu Lei [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, CT 06269 (United States); Li Changming, E-mail: ecmli@ntu.edu.sg [School of Chemical and Biomedical Engineering and Center for Advanced Bionanosystems, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457 (Singapore)

    2011-01-10

    A sensitive electrochemical sensor has been fabricated to detect ultratrace nitroaromatic explosives using ordered mesoporus carbon (OMC). OMC was synthesized and characterized by scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption measurements. Glassy carbon electrodes functionalized with OMC show high sensitivity of 62.7 {mu}A cm{sup -2} per ppb towards 2,4,6-trinitrotoluene (TNT). By comparison with other materials such as carbon nanotubes and ordered mesoporous silica, it is found that the high performance of OMC toward sensing TNT is attributed to its large specific surface area and fast electron transfer capability. As low as 0.2 ppb TNT, 1 ppb 2,4-dinitrotoluene and 1 ppb 1,3-dinitrobenzene can be detected on OMC based electrodes. This work renders new opportunities to detect ultratrace explosives for applications of environment protections and home securities against chemical warfare agents.

  16. One-Step Hydrothermal-Electrochemical Route to Carbon-Stabilized Anatase Powders

    Science.gov (United States)

    Tao, Ying; Yi, Danqing; Zhu, Baojun

    2013-04-01

    Black carbon-stabilized anatase particles were prepared by a simple one-step hydrothermal-electrochemical method using glucose and titanium citrate as the carbon and titanium source, respectively. Morphological, chemical, structural, and electrochemical characterizations of these powders were carried out by Raman spectroscopy, Fourier-transform infrared spectroscopy, x-ray diffraction, scanning electron microscopy, and cyclic voltammetry. It was revealed that 200-nm carbon/anatase TiO2 was homogeneously dispersed, and the powders exhibited excellent cyclic performance at high current rates of 0.05 V/s. The powders are interesting potential materials that could be used as anodes for lithium-ion batteries.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  18. Water uptake in free films and coatings using the Brasher and Kingsbury equation: a possible explanation of the different values obtained by electrochemical Impedance spectroscopy and gravimetry

    International Nuclear Information System (INIS)

    Vosgien Lacombre, C.; Bouvet, G.; Trinh, D.; Mallarino, S.; Touzain, S.

    2017-01-01

    For many years, the water uptake in organic coatings was measured by EIS and/or gravimetry but differences in water content values were found in almost all studies. The Brasher-Kingsbury equation used in the electrochemical analysis (EIS) is often criticized because elementary assumptions may be unvalid. The origin of the discrepancy between both methods is still of interest because many questions remain open and this study aims to provide new insights to these questions. In this work, free films and coatings of a model epoxy-amine system were immersed in a 3 wt.% NaCl solution. The water uptake in free films was evaluated using gravimetric measurements and EIS, using the Basher-Kingsbury equation. The mass of free-films used in the EIS tests was measured and compare to gravimetric measurements while the water uptake (EIS) in free films was compared to that obtained with coatings. It was found that the mass increase of free films tested with EIS was in agreement with gravimetric measurements but was always lower than the water uptake obtained by EIS. Moreover, the water uptake in free films (EIS) was different from that obtained with coatings. In all cases, it was found that the Basher-Kingsbury equation overestimated the water uptake. It appears that the differences between EIS and gravimetric measurements can be analyzed in terms of geometrical effects. Indeed, the swelling in free films and coatings can be monitored by DMA and SECM during ageing. Finally, by mixing the experimental swelling data and the Brasher-Kingsbury equation, the same value of water uptake was obtained by EIS and gravimetry for coatings.

  19. Electrochemical preparation of poly(methylene blue)/graphene nanocomposite thin films

    International Nuclear Information System (INIS)

    Erçarıkcı, Elif; Dağcı, Kader; Topçu, Ezgi; Alanyalıoğlu, Murat

    2014-01-01

    Highlights: • Poly(MB)/graphene thin films are prepared by a simple electrochemical approach. • Graphene layers in the film show a broad band in visible region of absorbance spectra. • Morphology of composite films indicates both disordered and ordered regions. • XRD reveals that nanocomposite films include rGO layers after electropolymerization process. • Chemically prepared graphene is better than electrochemically prepared graphene for electrooxidation of nitrite. - Abstract: Poly(methylene blue)/graphene nanocomposite thin films were prepared by electropolymerization of methylene blue in the presence of graphene which have been synthesized by two different methods of a chemical oxidation process and an electrochemical approach. Synthesized nanocomposite thin films were characterized by using cyclic voltammetry, UV–vis. absorption spectroscopy, powder X-ray diffraction, and scanning tunneling microscopy techniques. Electrocatalytical properties of prepared poly(methylene blue)/graphene nanocomposite films were compared toward electrochemical oxidation of nitrite. Under optimized conditions, electrocatalytical effect of nanocomposite films of chemically prepared graphene through electrochemical oxidation of nitrite was better than that of electrochemically prepared graphene

  20. Electrochemical performance studies of MnO2 nanoflowers recovered from spent battery

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  1. Synthesis and electrochemical study of Pt-based nanoporous materials

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  2. Synthesis and electrochemical study of Pt-based nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-10-01

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

  3. Synthesis and electrochemical study of Pt-based nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-10-01

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

  4. Electrochemical Properties for Co-Doped Pyrite with High Conductivity

    Directory of Open Access Journals (Sweden)

    Yongchao Liu

    2015-09-01

    Full Text Available In this paper, the hydrothermal method was adopted to synthesize nanostructure Co-doped pyrite (FeS2. The structural properties and morphology of the synthesized materials were characterized using X-ray diffraction (XRD and scanning electron microscopy (SEM, respectively. Co in the crystal lattice of FeS2 could change the growth rate of different crystal planes of the crystal particles, which resulted in various polyhedrons with clear faces and sharp outlines. In addition, the electrochemical performance of the doping pyrite in Li/FeS2 batteries was evaluated using the galvanostatic discharge test, cyclic voltammetry and electrochemical impedance spectroscopy. The results showed that the discharge capacity of the doped material (801.8 mAh·g−1 with a doping ratio of 7% was significantly higher than that of the original FeS2 (574.6 mAh·g−1 because of the enhanced conductivity. Therefore, the doping method is potentially effective for improving the electrochemical performance of FeS2.

  5. Improved electrochemical performance of hierarchical porous carbon/polyaniline composites

    International Nuclear Information System (INIS)

    Hu Juan; Wang Huanlei; Huang Xiao

    2012-01-01

    Highlights: ► Polyaniline-coated hierarchical porous carbon (HPC) composites have been synthesized by in situ polymerization. ► The HPC/polyaniline composite has significantly better electrochemical capacitance performance than pure HPC and polyaniline. ► The amount of polyaniline loading has a significant effect on the composites’ electrochemical performances. - Abstract: Polyaniline (PANI)-coated hierarchical porous carbon (HPC) composites (HPC/PANI) for use as supercapacitor electrodes were prepared by in situ chemical oxidation polymerization at 273 K of an aniline solution containing well-dispersed HPC particles. After polymerization, a thin layer of PANI was coated on the surface of the HPC particles, which was confirmed by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM) and scanning electron microscopy (SEM). Compared to pure PANI and HPC, the electrochemical capacitance performance of the composites was significantly improved. The highest specific capacitance of the composites obtained is 478 F g −1 at 1 mV s −1 , which is more than twice as that of pure PANI and three times as that of pure HPC. Because of the influence from the hierarchical pore structure of the carbon material, the calculated specific capacitance of PANI in the composite (pseudocapacitance contribution from PANI) is almost one magnitude higher than that of pure PANI.

  6. Electrochemical copolymerization of thiophene derivatives; a precursor to photovoltaic devices

    International Nuclear Information System (INIS)

    Kumar, Prajwal; Ranjith, K.; Gupta, Satyajit; Ramamurthy, Praveen C.

    2011-01-01

    Highlights: → This work presents an electrochemical technique for the polymerization and copolymerization of thiophene derivatives. → Copolymerization of thiophene based monomers like 7,9-dithiophene-2yl-8H-cyclopenta[a]acenaphthalene-8-one and 3-hexylthiophene are synthesized. → Study of the structural, optical, thermal, conductivity, morphological, band gap and impedance measurements of the copolymer indicates a suitable material for photovoltaic applications. - Abstract: This work presents an electrochemical technique for the polymerization and copolymerization of thiophene derivatives like 7,9-dithiophene-2yl-8H-cyclopenta[a]acenaphthalene-8-one and 3-hexylthiophene. The structural characterization of chemically synthesized monomers and electrochemically synthesized polymers was carried out by nuclear magnetic resonance and Fourier transform infrared spectroscopy. Thermal characterizations indicate that copolymer has increased thermal stability than that of homopolymer. Morphological studies of the polymerized films carried out by scanning electron microscopy shows network structure of copolymer. Optical properties of the homopolymers and copolymer were studied by UV-visible spectrometer and it was observed that band gap of copolymer is less than the homopolymers. HOMO and LUMO levels, band gap values of the respective polymers were also calculated from the cyclic voltammetry technique with various scan rates. By the peak current obtained from various scan rates shows that all polymerization reactions are diffusion controlled process. Charge transfer resistances of polymers were determined using Nyquist plots. Conductivity of synthesized polymers shows higher conductivity for copolymer than homopolymers.

  7. SUPPLEMENTARY INFORMATION A combined Electrochemical ...

    Indian Academy of Sciences (India)

    DELL

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

  8. Electrolytes for magnesium electrochemical cells

    Science.gov (United States)

    Burrell, Anthony K.; Sa, Niya; Proffit, Danielle Lee; Lipson, Albert; Liao, Chen; Vaughey, John T.; Ingram, Brian J.

    2017-07-04

    An electrochemical cell includes a high voltage cathode configured to operate at 1.5 volts or greater; an anode including Mg.sup.0; and an electrolyte including an ether solvent and a magnesium salt; wherein: a concentration of the magnesium salt in the ether is 1 M or greater.

  9. All-Polymer Electrochemical Sensors

    DEFF Research Database (Denmark)

    Kafka, Jan Robert

    This thesis presents fabrication strategies to produce different types of all-polymer electrochemical sensors based on electrodes made of the highly conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Three different systems are presented, fabricated either by using microdrilling or by hot...

  10. Electrochemical method for transferring graphene

    DEFF Research Database (Denmark)

    2015-01-01

    The present application discloses a method for separating a graphene-support layer laminate from a conducting substrate-graphene-support layer laminate, using a gentle, controllable electrochemical method. In this way, substrates which are fragile, expensive or difficult to manufacture can be used...... - and even re-used - without damage or destruction of the substrate or the graphene....

  11. Materials for electrochemical device safety

    Science.gov (United States)

    Vissers, Daniel R.; Amine, Khalil; Thackeray, Michael M.; Kahaian, Arthur J.; Johnson, Christopher S.

    2015-04-07

    An electrochemical device includes a thermally-triggered intumescent material or a gas-triggered intumescent material. Such devices prevent or minimize short circuits in a device that could lead to thermal run-away. Such devices may include batteries or supercapacitors.

  12. (Bio)electrochemical ammonia recovery

    NARCIS (Netherlands)

    Kuntke, P.; Sleutels, T.H.J.A.; Rodríguez Arredondo, M.; Georg, S.; Barbosa, S.G.; Heijne, Ter A.; Hamelers, Hubertus V.M.; Buisman, C.J.N.

    2018-01-01

    In recent years, (bio)electrochemical systems (B)ES have emerged as an energy efficient alternative for the recovery of TAN (total ammonia nitrogen, including ammonia and ammonium) from wastewater. In these systems, TAN is removed or concentrated from the wastewater under the influence of an

  13. Graphene-based electrochemical supercapacitors

    Indian Academy of Sciences (India)

    Graphenes prepared by three different methods have been investigated as electrode materials in electrochemical supercapacitors. The samples prepared by exfoliation of graphitic oxide and by the transformation of nanodiamond exhibit high specific capacitance in aq. H2SO4, the value reaching up to 117 F/g. By using an ...

  14. Graphene-based electrochemical supercapacitors

    Indian Academy of Sciences (India)

    WINTEC

    been great interest in graphene, which constitutes an entirely new class of carbon. Electrical characteriza- tion of single-layer graphene has been reported. 12,13. We have investigated the use of graphene as elec- trode material in electrochemical supercapacitors. For this purpose, we have employed graphene prepared.

  15. SURFACE PROPERTIES OF ELECTROCHEMICALLY REDUCED ...

    African Journals Online (AJOL)

    DJFLEX

    A viscose rayon based activated carbon cloth (ACC) was electrochemically reduced ..... bath of liquid nitrogen at a temperature of 77 K. ... that above 59,400 c/g extent of oxidation, the ..... ACC react with aldehyde groups to produce ether.

  16. ELECTROCHEMICAL DETERMINATION OF ETHANOL, 2 ...

    African Journals Online (AJOL)

    2014-12-31

    Dec 31, 2014 ... ABSTRACT. In this work, we present the modification of a glassy carbon electrode with nickel oxide film which is performed in two successive steps. In the first one, the electrochemical deposition of metallic nickel on the glassy carbon electrode (GCE) is achieved in 0.1M boric acid; in the second step, the ...

  17. Electron microscopy (nonbiological)

    International Nuclear Information System (INIS)

    Cowley, J.M.

    1986-01-01

    The period 1982-1985, which is covered by this review, has seen major advances in the capabilities of the commercially available instruments. The new electron microscopes operating in the range of 300-400 keV have provided important improvements in the resolution available and in the possibilities for microanalysis of very small specimen areas. Correspondingly there has been a broadening in the range of possible applications of the techniques. Electron microscopy has become a much more powerful tool for studies of semiconductors and catalysts, for example, and offers promise of a major revolution in surface science. The major industrial laboratories, in particular, are investing in million-dollar instruments and in the highly skilled scientists needed to run them because the capabilities of the new instruments are seen to have immediate practical applications to current industrial research. Unfortunately all of the new instruments and most of the skilled users come from overseas. The American instrument industry, although showing some limited signs of life, is not yet in a position to compete in this lucrative market and the training of electron optics specialists in this country is far from meeting the demand. The increased sophistication required for both the operation of the instruments and the interpretation of the observation requires that the quality as well as the quantity of trainees must be improved. 62 references

  18. Ultrafast scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Botkin, D.A. [California Univ., Berkeley, CA (United States). Dept. of Physics]|[Lawrence Berkeley Lab., CA (United States)

    1995-09-01

    I have developed an ultrafast scanning tunneling microscope (USTM) based on uniting stroboscopic methods of ultrafast optics and scanned probe microscopy to obtain nanometer spatial resolution and sub-picosecond temporal resolution. USTM increases the achievable time resolution of a STM by more than 6 orders of magnitude; this should enable exploration of mesoscopic and nanometer size systems on time scales corresponding to the period or decay of fundamental excitations. USTM consists of a photoconductive switch with subpicosecond response time in series with the tip of a STM. An optical pulse from a modelocked laser activates the switch to create a gate for the tunneling current, while a second laser pulse on the sample initiates a dynamic process which affects the tunneling current. By sending a large sequence of identical pulse pairs and measuring the average tunnel current as a function of the relative time delay between the pulses in each pair, one can map the time evolution of the surface process. USTM was used to measure the broadband response of the STM`s atomic size tunnel barrier in frequencies from tens to hundreds of GHz. The USTM signal amplitude decays linearly with the tunnel junction conductance, so the spatial resolution of the time-resolved signal is comparable to that of a conventional STM. Geometrical capacitance of the junction does not appear to play an important role in the measurement, but a capacitive effect intimately related to tunneling contributes to the measured signals and may limit the ultimate resolution of the USTM.

  19. Superconductivity and electron microscopy

    International Nuclear Information System (INIS)

    Hawkes, P.W.; Valdre, U.

    1977-01-01

    In this review article, two aspects of the role of superconductivity in electron microscopy are examined: (i) the development of superconducting devices (mainly lenses) and their incorporation in electron microscopes; (ii) the development of electron microscope techniques for studying fundamental and technological problems associated with superconductivity. The first part opens with a brief account of the relevant properties of conventional lenses, after which the various types of superconducting lenses are described and their properties compared. The relative merits and inconveniences of superconducting and conventional lenses are examined, particular attention being paid to the spherical and chromatic aberration coefficients at accelerating voltages above a megavolt. This part closes with a survey of the various microscope designs that have been built or proposed, incorporating superconducting components. In the second part, some methods that have been or might be used in the study of superconductivity in the electron microscope are described. A brief account of the types of application for which they are suitable is given. (author)

  20. Transmission acoustic microscopy investigation

    Science.gov (United States)

    Maev, Roman; Kolosov, Oleg; Levin, Vadim; Lobkis, Oleg

    The nature of acoustic contrast, i.e. the connection of the amplitude and phase of the output signal of the acoustic microscope with the local values of the acoustic parameters of the sample (density, elasticity, viscosity) is a central problem of acoustic microscopy. A considerable number of studies have been devoted to the formation of the output signal of the reflection scanning acoustic microscope. For the transmission acoustic microscope (TAM) this problem has remained almost unstudied. Experimental investigation of the confocal system of the TAM was carried out on an independently manufactured laboratory mockup of the TAM with the working frequency of the 420 MHz. Acoustic lenses with the radius of curvature of about 500 microns and aperture angle of 45 deg were polished out in the end faces of two cylindrical sound conductors made from Al2O3 single crystals with an axis parallel to the axis C of the crystal (the length of the sound conductor is 20 mm; diameter, 6 mm). At the end faces of the sound conductor, opposite to the lenses, CdS transducers with a diameter of 2 mm were disposed. The electric channel of the TAM provided a possibility for registering the amplitude of the microscope output signal in the case of the dynamic range of the 50 dB.

  1. Innovative Strategies for Clinical Microscopy Instruction: Virtual Versus Light Microscopy.

    Science.gov (United States)

    McDaniel, M Jane; Russell, Gregory B; Crandall, Sonia J

    2018-06-01

    The purpose of the study was to compare virtual microscopy with light microscopy to determine differences in learning outcomes and learner attitudes in teaching clinical microscopy to physician assistant (PA) students. A prospective, randomized, crossover design study was conducted with a convenience sample of 67 first-year PA students randomized to 2 groups. One group used light microscopes to find microscopic structures, whereas the other group used instructor-directed video streaming of microscopic elements. At the midpoint of the study, the groups switched instructional strategies. Learning outcomes were assessed via posttest after each section of the study, with comparison of final practical examination results to previous cohorts. Attitudes about the 2 educational strategies were assessed through a postcourse questionnaire with a Likert scale. Analysis of the first posttest demonstrated that students in the video-streamed group had significantly better learning outcomes than those in the light microscopy group (P = .004; Cohen's d = 0.74). Analysis of the posttest after crossover showed no differences between the 2 groups (P = .48). Between the 2 posttests, students first assigned to the light microscopy group scored a 6.6 mean point increase (±10.4 SD; p = .0011), whereas students first assigned to the virtual microscopy group scored a 1.3 mean point increase (±7.1 SD; p = .29). The light microscopy group improved more than the virtual microscopy group (P = .019). Analysis of practical examination data revealed higher scores for the study group compared with 5 previous cohorts of first-year students (P virtual microscopy to traditional light microscopy. Virtual microscopy is an effective educational strategy, and students prefer this method when learning to interpret images of clinical specimens.

  2. NDE Acoustic Microscopy Research Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The purpose is to develop advanced, more effective high-resolution micro-NDE materials characterization methods using scanning acoustic microscopy. The laboratory's...

  3. Magnetic Resonance Force Microscopy System

    Data.gov (United States)

    Federal Laboratory Consortium — The Magnetic Resonance Force Microscopy (MRFM) system, developed by ARL, is the world's most sensitive nuclear magnetic resonance (NMR) spectroscopic analysis tool,...

  4. High damage tolerance of electrochemically lithiated silicon

    Science.gov (United States)

    Wang, Xueju; Fan, Feifei; Wang, Jiangwei; Wang, Haoran; Tao, Siyu; Yang, Avery; Liu, Yang; Beng Chew, Huck; Mao, Scott X.; Zhu, Ting; Xia, Shuman

    2015-01-01

    Mechanical degradation and resultant capacity fade in high-capacity electrode materials critically hinder their use in high-performance rechargeable batteries. Despite tremendous efforts devoted to the study of the electro–chemo–mechanical behaviours of high-capacity electrode materials, their fracture properties and mechanisms remain largely unknown. Here we report a nanomechanical study on the damage tolerance of electrochemically lithiated silicon. Our in situ transmission electron microscopy experiments reveal a striking contrast of brittle fracture in pristine silicon versus ductile tensile deformation in fully lithiated silicon. Quantitative fracture toughness measurements by nanoindentation show a rapid brittle-to-ductile transition of fracture as the lithium-to-silicon molar ratio is increased to above 1.5. Molecular dynamics simulations elucidate the mechanistic underpinnings of the brittle-to-ductile transition governed by atomic bonding and lithiation-induced toughening. Our results reveal the high damage tolerance in amorphous lithium-rich silicon alloys and have important implications for the development of durable rechargeable batteries. PMID:26400671

  5. Electrochemical binding and wiring in battery materials

    Energy Technology Data Exchange (ETDEWEB)

    Pejovnik, S. [National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia); Faculty of Chemistry and Chemical Technology, Askerceva 5, SI-1000 Ljubljana (Slovenia); Dominko, R.; Bele, M.; Gaberscek, M.; Jamnik, J. [National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia)

    2008-10-01

    Binders in battery electrodes not only provide mechanical cohesiveness during battery operation but can also affect the electrode properties via the surface modification. Using atomic force microscopy (AFM), we study the surface structuring of three binders: polyvinylidene fluoride (PVdF), carboxymethyl cellulose (CMC) and gelatin. We try to find correlation between the observed structures and the measured electrochemical charge-discharge characteristics. We further measure the binding ability of gelatin adsorbed from solutions of different pHs. While the best binding ability of gelatin is obtained at pH about 9, the least polarization is observed at pH 12. Both properties are explained based on the observed gelatin structuring as a function of pH. In the second part of this study, gelatin is used as a surface agent that dictates the organization of nanometre-sized carbon black particles around micrometre-sized cathodic active particles. Using microcontact impedance measurements on polished pellets we show that using gelatin-forced carbon black deposition the average electronic resistance around LiMn{sub 2}O{sub 4} particles is decreased by more than two orders of magnitude. We believe that it is this decrease in resistance that improves significantly the rate performance of various cathode materials, such as LiMn{sub 2}O{sub 4} and LiCoO{sub 2}. (author)

  6. 3,5-Diamino-1,2,4-triazole@electrochemically reduced graphene oxide film modified electrode for the electrochemical determination of 4-nitrophenol

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  7. Ultraporous poly(3,4-ethylenedioxythiophene) for nanometric electrochemical supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Aradilla, David [Departament d' Enginyeria Quimica, ETSEIB, Universitat Politecnica de Catalunya, Avda. Diagonal 647, Barcelona E-08028 (Spain); Center for Research in Nano-Engineering, Universitat Politecnica de Catalunya, Campus Sud, Edifici C' , C/Pasqual i Vila s/n, Barcelona E-08028 (Spain); Estrany, Francesc [Center for Research in Nano-Engineering, Universitat Politecnica de Catalunya, Campus Sud, Edifici C' , C/Pasqual i Vila s/n, Barcelona E-08028 (Spain); Departament d' Enginyeria Quimica, EUETIB, Universitat Politecnica de Catalunya, Comte d' Urgell 187, Barcelona E-08036 (Spain); Armelin, Elaine [Departament d' Enginyeria Quimica, ETSEIB, Universitat Politecnica de Catalunya, Avda. Diagonal 647, Barcelona E-08028 (Spain); Center for Research in Nano-Engineering, Universitat Politecnica de Catalunya, Campus Sud, Edifici C' , C/Pasqual i Vila s/n, Barcelona E-08028 (Spain); Aleman, Carlos, E-mail: carlos.aleman@upc.edu [Departament d' Enginyeria Quimica, ETSEIB, Universitat Politecnica de Catalunya, Avda. Diagonal 647, Barcelona E-08028 (Spain); Center for Research in Nano-Engineering, Universitat Politecnica de Catalunya, Campus Sud, Edifici C' , C/Pasqual i Vila s/n, Barcelona E-08028 (Spain)

    2012-04-30

    Ultrathin films of poly(3,4-ethylenedioxythiophene) (PEDOT) have been prepared by electropolymerization on steel and indium-tin oxide (ITO) substrates under identical experimental conditions. Scanning electron microscopy and atomic force microscopy indicate that the substrate affects dramatically both the morphology and topography of films when the polymerization times are very short. An ultraporous three-dimensional network involving ultrathin sticks with a fiber-like morphology was formed on ITO. Asymmetric and symmetric supercapacitors have been fabricated by assembling electrodes of PEDOT deposited on ITO and steel. The specific capacitance, electrochemical stability, supercapacitor behavior and Coulombic efficiency measured for devices with an ITO/steel configuration were similar to those reported for advanced PEDOT-inorganic hybrid composites. Furthermore, the performance of the ITO/steel assembly is higher than those determined for symmetric supercapacitors derived from two identical electrodes of PEDOT deposited on steel or on ITO. The unique properties of the asymmetric supercapacitors have been attributed to the ultraporous structure of the ultrathin films deposited on ITO, which is not significantly perturbed when the device is submitted to a very high number of consecutive oxidation-reduction processes, and the different electroactivities of the two electrodes. - Highlights: Black-Right-Pointing-Pointer Ultrathin poly(3,4-ethylenedioxythiophene) (PEDOT) films show fiber-like morphology. Black-Right-Pointing-Pointer The porosity of ultrathin PEDOT films induces a very high electrochemical stability. Black-Right-Pointing-Pointer Asymmetric supercapacitors made of ultrathin PEDOT behave like hybrid nanocomposites.

  8. Ultraporous poly(3,4-ethylenedioxythiophene) for nanometric electrochemical supercapacitor

    International Nuclear Information System (INIS)

    Aradilla, David; Estrany, Francesc; Armelin, Elaine; Alemán, Carlos

    2012-01-01

    Ultrathin films of poly(3,4-ethylenedioxythiophene) (PEDOT) have been prepared by electropolymerization on steel and indium-tin oxide (ITO) substrates under identical experimental conditions. Scanning electron microscopy and atomic force microscopy indicate that the substrate affects dramatically both the morphology and topography of films when the polymerization times are very short. An ultraporous three-dimensional network involving ultrathin sticks with a fiber-like morphology was formed on ITO. Asymmetric and symmetric supercapacitors have been fabricated by assembling electrodes of PEDOT deposited on ITO and steel. The specific capacitance, electrochemical stability, supercapacitor behavior and Coulombic efficiency measured for devices with an ITO/steel configuration were similar to those reported for advanced PEDOT-inorganic hybrid composites. Furthermore, the performance of the ITO/steel assembly is higher than those determined for symmetric supercapacitors derived from two identical electrodes of PEDOT deposited on steel or on ITO. The unique properties of the asymmetric supercapacitors have been attributed to the ultraporous structure of the ultrathin films deposited on ITO, which is not significantly perturbed when the device is submitted to a very high number of consecutive oxidation–reduction processes, and the different electroactivities of the two electrodes. - Highlights: ► Ultrathin poly(3,4-ethylenedioxythiophene) (PEDOT) films show fiber-like morphology. ► The porosity of ultrathin PEDOT films induces a very high electrochemical stability. ► Asymmetric supercapacitors made of ultrathin PEDOT behave like hybrid nanocomposites.

  9. Molecularly imprinted electrochemical sensor based on nickel nanoparticle-modified electrodes for phenobarbital determination

    International Nuclear Information System (INIS)

    Yu, Hui Cheng; Huang, Xue Yi; Lei, Fu Hou; Tan, Xue Cai; Wei, Yi Chun; Li, Hao

    2014-01-01

    Highlights: • Uniform Ni nanoparticles were synthesized. • A Ni nanoparticle-modified imprinted sensor was developed to detect phenobarbital. • The modified sensor exhibited high sensitivity for phenobarbital. • The electrochemical properties of the modified sensor were investigated. • The prepared sensor was applied to detect phenobarbital in fish samples. - Abstract: Uniform nickel nanoparticles were applied to improve the sensitivity of sensors for phenobarbital (PB) determination. A Ni nanoparticle-modified imprinted electrochemical sensor was developed by thermal polymerization with the use of methacrylic acid as the functional monomer and ethylene glycol maleic rosinate acrylate as the crosslinking agent. The chemical structures and morphologies of the imprinted films were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. The success of the fabrication of Ni nanoparticles, as well as the Ni nanoparticle-modified imprinted electrochemical sensor, was confirmed by the analytical results. The electrochemical properties of the modified molecularly imprinted and non-imprinted polymer sensors were investigated by cyclic voltammetry, differential pulse voltammetry, electrochemical impedance spectroscopy, and chronoamperometry. Results showed that the electrochemical properties of the molecularly imprinted sensor were remarkably different from those of the non-imprinted sensor. Linear responses of the imprinted sensor to PB were observed for concentrations ranging from 1.4 × 10 −7 mol L −1 to 1.3 × 10 −4 mol L −1 (r 2 = 0.9976), with a detection limit of 8.2 × 10 −9 mol L −1 (S/N = 3). The imprinted electrochemical sensor was used to determine PB in actual fish samples, in which average recoveries between 95.60% and 104.67% were achieved. The developed Ni nanoparticle-modified electrochemical sensor exhibited high sensitivity, high selectivity, and good recovery

  10. Electronic Blending in Virtual Microscopy

    Science.gov (United States)

    Maybury, Terrence S.; Farah, Camile S.

    2010-01-01

    Virtual microscopy (VM) is a relatively new technology that transforms the computer into a microscope. In essence, VM allows for the scanning and transfer of glass slides from light microscopy technology to the digital environment of the computer. This transition is also a function of the change from print knowledge to electronic knowledge, or as…

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-11-15

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

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

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  13. Synthesis, characterization and electrochemical performance of core/shell structured carbon coated silicon powders for lithium ion battery negative electrodes

    Directory of Open Access Journals (Sweden)

    Tuğrul Çetinkaya

    2017-06-01

    Full Text Available Surface of nano silicon powders were coated with amorphous carbon by pyrolysis of polyacronitrile (PAN polymer. Microstructural characterization of amorphous carbon coated silicon powders (Si-C were carried out using scanning electron microscopy (SEM and thickness of carbon coating is defined by transmission electron microscopy (TEM. Elemental analyses of Si-C powders were performed using energy dispersive X-ray spectroscopy (EDS. Structural and phase characterization of Si-C composite powders were investigated using X-ray diffractometer (XRD and Raman spectroscopy. Produced Si-C powders were prepared as an electrode on the copper current collector and electrochemical tests were carried out using CR2016 button cells at 200 mA/g constant current density. According to electrochemical test results, carbon coating process enhanced the electrochemical performance by reducing the problems stem from volume change and showed 770 mAh/g discharge capacity after 30 cycles.

  14. Electrochemical functionalization of glassy carbon electrode by reduction of diazonium cations in protic ionic liquid

    International Nuclear Information System (INIS)

    Shul, Galyna; Ruiz, Carlos Alberto Castro; Rochefort, Dominic; Brooksby, Paula A.; Bélanger, Daniel

    2013-01-01

    Protic ionic liquid based on 2-methoxypyridine and trifluoroacetic acid was used as electrolyte for the functionalization of a glassy carbon electrode surface by electrochemical reduction of in situ generated 4-chlorobenzene diazonium and 4-nitrobenzene diazonium cations. The diazonium cations were synthesized in an electrochemical cell by reaction of the corresponding amines with NaNO 2 dissolved in protic ionic liquid. The resulting electrografted organic layers exhibit similar properties to those layers obtained by the derivatization from isolated diazonium salts dissolved in protic ionic liquid. Functionalized glassy carbon electrode surfaces were characterized by cyclic voltammetry, Fourier transform infrared and X-ray photoelectron spectroscopies. Atomic force microscopy thickness measurements revealed that, in our experimental conditions, the use of protic ionic liquid led to the formation of film with a thickness of about 1.5 nm. It is also demonstrated that the nitrobenzene chemisorbed on glassy carbon electrode or dissolved in protic ionic liquid undergoes electrochemical conversion to hydroxyaminobenzene

  15. Electrochemical Impedance Spectroscopic Analysis of RuO2 Based Thick Film pH Sensors

    International Nuclear Information System (INIS)

    Manjakkal, Libu; Djurdjic, Elvira; Cvejin, Katarina; Kulawik, Jan; Zaraska, Krzysztof; Szwagierczak, Dorota

    2015-01-01

    The conductimetric interdigitated thick film pH sensors based on RuO 2 were fabricated and their electrochemical reactions with solutions of different pH values were studied by electrochemical impedance spectroscopy (EIS) technique. The microstructural properties and composition of the sensitive films were examined by scanning electron microscopy, X-ray energy dispersive spectroscopy and Raman spectroscopy. The EIS analysis of the sensor was carried out in the frequency range 10 mHz–2 MHz for pH values of test solutions 2–12. The electrical parameters of the sensor were found to vary with changing pH. The conductance and capacitance of the film were distinctly dependent on pH in the low frequency range. The Nyquist and Bode plots derived from the impedance data for the metal oxide thick film pH sensor provided information about the underlying electrochemical reactions

  16. Optical and structural properties of porous zinc oxide fabricated via electrochemical etching method

    International Nuclear Information System (INIS)

    Ching, C.G.; Lee, S.C.; Ooi, P.K.; Ng, S.S.; Hassan, Z.; Hassan, H. Abu; Abdullah, M.J.

    2013-01-01

    Highlights: • Hillock like porous structure zinc oxide was obtained via electrochemical etching. • Anisotropic dominance etching process by KOH etchant. • Reststrahlen features are sensitive to multilayer porous structure. • Determination of porosity from IR reflectance spectrum. -- Abstract: We investigated the optical and structural properties of porous zinc oxide (ZnO) thin film fabricated by ultraviolet light-assisted electrochemical etching. This fabrication process used 10 wt% potassium hydroxide solution as an electrolyte. Hillock-like porous ZnO films were successfully fabricated according to the field emission scanning electron microscopy results. The cross-sectional study of the sample indicated that anisotropic-dominated etching process occurred. However, the atomic force microscopic results showed an increase in surface roughness of the sample after electrochemical etching. A resonance hump induced by the porous structure was observed in the infrared reflectance spectrum. Using theoretical modeling technique, ZnO porosification was verified, and the porosity of the sample was determined

  17. Multilayered films of cobalt oxyhydroxide nanowires/manganese oxide nanosheets for electrochemical capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Huajun [State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, Zhejiang University of Technology, Hangzhou 310014 (China); ARC Centre of Excellence for Functional Nanomaterials, School of Chemical Engineering and AIBN, The University of Queensland, St Lucia, Brisbane, QLD 4072 (Australia); Tang, Fengqiu; Mukherji, Aniruddh; Yan, Xiaoxia; Wang, Lianzhou (Max) Lu, Gao Qing [ARC Centre of Excellence for Functional Nanomaterials, School of Chemical Engineering and AIBN, The University of Queensland, St Lucia, Brisbane, QLD 4072 (Australia); Lim, Melvin [Division of Environmental and Water Resources Engineering, School of Civil and Environmental Engineering, Nanyang Technological University, 639798 (Singapore)

    2010-01-15

    Multilayered films of cobalt oxyhydroxide nanowires (CoOOHNW) and exfoliated manganese oxide nanosheet (MONS) are fabricated by potentiostatic deposition and electrostatic self-assembly on indium-tin oxide coated glass substrates. The morphology and chemical composition of these films are characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectra (XPS) and the potential application as electrochemical supercapacitors are investigated using cyclic voltammetry and charge-discharge measurements. These ITO/CoOOHNW/MONS multilayered film electrodes exhibit excellent electrochemical capacitance properties, including high specific capacitance (507 F g{sup -1}) and long cycling durability (less 2% capacity loss after 5000 charge/discharge cycles). These characteristics indicate that these newly developed films may find important application for electrochemical capacitors. (author)

  18. An Electrochemical Investigation of Nano Cerium Oxide/Graphene as an Electrode Material for Supercapacitors

    Directory of Open Access Journals (Sweden)

    Mohammadreza Shishesaz

    2015-01-01

    In this paper, the effect of cationic and anionic ion sizes on the charge storage capability of graphene nanosheets, is investigated. Electrochemical properties of produced electrode are studied using cyclic voltammetry (CV and electrochemical impedance spectroscopy (EIS techniques, in 3M NaCl, NaOH and KOH electrolytes. Scanning electron microscopy (SEM is used to characterize the microstructure and nature of prepared electrode. SEM images and XRD patterns confirm the layered structure (12 nm thickness of the used graphene with an interlayer distance of 3.36 (Å. The electrochemical results and the ratio of q*O/q*T confirm a good charge storage and charge delivering capability of prepared electrode in 3M NaCl electrolyte. Charge/discharge cycling test shows a good reversibility and confirms that solution resistance will increase after 500 cycles.

  19. Electrochemically Controlled Ion-exchange Property of Carbon Nanotubes/Polypyrrole Nanocomposite in Various Electrolyte Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Daiwon [Pacific Northwest National Laboratory, 902 Battelle Boulevard P.O. Box 999 Richland WA 99352 USA; Zhu, Chengzhou [School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164-2920 United States; Fu, Shaofang [School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164-2920 United States; Du, Dan [School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164-2920 United States; Engelhard, Mark H. [Pacific Northwest National Laboratory, 902 Battelle Boulevard P.O. Box 999 Richland WA 99352 USA; Lin, Yuehe [Pacific Northwest National Laboratory, 902 Battelle Boulevard P.O. Box 999 Richland WA 99352 USA; School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164-2920 United States

    2016-09-15

    The electrochemically controlled ion-exchange properties of multi-wall carbon nanotube (MWNT)/electronically conductive polypyrrole (PPy) polymer composite in the various electrolyte solutions have been investigated. The ion-exchange behavior, rate and capacity of the electrochemically deposited polypyrrole with and without carbon nanotube (CNT) were compared and characterized using cyclic voltammetry (CV), chronoamperometry (CA), electrochemical quartz crystal microbalance (EQCM), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It has been found that the presence of carbon nanotube backbone resulted in improvement in ion-exchange rate, stability of polypyrrole, and higher anion loading capacity per PPy due to higher surface area, electronic conductivity, porous structure of thin film, and thinner film thickness providing shorter diffusion path. Chronoamperometric studies show that electrically switched anion exchange could be completed more than 10 times faster than pure PPy thin film. The anion selectivity of CNT/PPy film is demonstrated using X-ray photoelectron spectroscopy (XPS).

  20. Influence of fabrication procedure on the electrochemical performance of Ag/AgCl reference electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Stoica, Daniela [Department of Biomedical and Inorganic Chemistry, Laboratoire National de Metrologie et d' Essais, 1 Rue Gaston Boissier, 75015 Paris (France); Brewer, Paul J., E-mail: paul.brewer@npl.co.uk [Analytical Science Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW (United Kingdom); Brown, Richard J.C. [Analytical Science Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW (United Kingdom); Fisicaro, Paola [Department of Biomedical and Inorganic Chemistry, Laboratoire National de Metrologie et d' Essais, 1 Rue Gaston Boissier, 75015 Paris (France)

    2011-11-30

    The influence of several parameters in the preparation procedure of thermal-electrolytic Ag/AgCl electrodes on the resulting electrode performance has been studied. In particular, we report the effect on electrode performance of subtle variations in the preparation of silver oxide paste used for electrode manufacture, in thermal annealing conditions employed and in the procedure for electrochemically converting a fraction of the electrode from silver to silver chloride. Scanning electron microscopy and electrochemical impedance spectroscopy have been used to study the characteristics of the electrodes produced. This work reveals a correlation between the electrochemical behaviour and surface physical characteristics - in particular electrode porosity. The outputs of this study have positive implications for improving the accuracy and comparability of primary pH measurement.

  1. Electrochemical catalytic activity of tungsten trioxide- modified graphite felt toward VO2+/VO2+ redox reaction

    International Nuclear Information System (INIS)

    Shen, Yang; Xu, Hongfeng; Xu, Pengcheng; Wu, Xiaoxin; Dong, Yiming; Lu, Lu

    2014-01-01

    A novel graphite felt electrode modified with tungsten trioxide (WO 3 ) was developed to improve the electrochemical performance of graphite felt toward the VO 2 + /VO 2+ redox pair. WO 3 was prepared using a hydrothermal method, and the morphology of WO 3 structures was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical property of WO 3 -modified graphite felt toward VO 2 + /VO 2+ was carefully characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. The hydrogen-vanadium redox flow battery (H-VRFB) test indicates that single cells using 1.1 mg cm −2 WO 3 -modified graphite felt exhibited excellent performance at 70 mA cm −2 , and the corresponding coulombic, voltage, and energy efficiencies were 99.1%, 88.66% and 87.86%, respectively

  2. Controlled amino-functionalization by electrochemical reduction of bromo and nitro azobenzene layers bound to Si(111) surfaces

    NARCIS (Netherlands)

    Ullien, D.; Thüne, P.C.; Jager, W.F.; Sudhölter, E.J.R.; De Smet, L.C.P.M.

    2014-01-01

    4-Nitrobenzenediazonium (4-NBD) and 4-bromobenzenediazonium (4-BBD) salts were grafted electrochemically onto H-terminated, p-doped silicon (Si) surfaces. Atomic force microscopy (AFM) and ellipsometry experiments clearly showed layer thicknesses of 2–7 nm, which indicate multilayer formation.

  3. Electrochemical stability and postmortem studies of Pt/SiC catalysts for polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Stamatin, Serban Nicolae; Spéder, József; Dhiman, Rajnish

    2015-01-01

    In the presented work, the electrochemical stability of platinized silicon carbide is studied. Postmortem transmission electron microscopy and X-ray photoelectron spectroscopy were used to document the change in the morphology and structure upon potential cycling of Pt/SiC catalysts. Two differen......, silicon carbide undergoes at least mild oxidation if not even silicon leaching....

  4. Electrochemical performance of Li4Mn5O12 nano-crystallites prepared by spray-drying-assisted solid state reactions

    International Nuclear Information System (INIS)

    Jiang, Y.P.; Xie, J.; Cao, G.S.; Zhao, X.B.

    2010-01-01

    Nanosized Li 4 Mn 5 O 12 has been synthesized by a spray-drying-assisted solid state method. The effect of spray drying and drying temperature on the microstructure and electrochemical performance of the final products has been investigated. The microstructure of the products has been characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The electrochemical performance of the products has been studied by galvanostatic cycling, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It has been found that the products prepared with a spray-drying pretreatment of the precursor exhibit a smaller grain size and a narrower size distribution than that prepared without the pretreatment. Among the three samples with a precursor pretreatment, that pretreated at 250 o C shows the best electrochemical performance due to the smallest grain size of below 50 nm and the narrowest size distribution.

  5. Electrochemical Behavior of Pure Copper in Phosphate Buffer Solutions: A Comparison Between Micro- and Nano-Grained Copper

    Science.gov (United States)

    Imantalab, O.; Fattah-alhosseini, A.; Keshavarz, M. K.; Mazaheri, Y.

    2016-02-01

    In this work, electrochemical behavior of annealed (micro-) and nano-grained pure copper (fabricated by accumulative roll bonding process) in phosphate buffer solutions of various pH values ranging from 10.69 to 12.59 has been studied. Before any electrochemical measurements, evaluation of microstructure was obtained by optical microscope and transmission electron microscopy. To investigate the electrochemical behavior of the samples, the potentiodynamic polarization, Mott-Schottky analysis, and electrochemical impedance spectroscopy (EIS) were carried out. Potentiodynamic polarization plots and EIS measurements revealed that as a result of grain refinement, the passive behavior of the nano-grained sample was improved compared to that of annealed pure copper. Also, Mott-Schottky analysis indicated that the passive films behaved as p-type semiconductors and grain refinement did not change the semiconductor type of passive films.

  6. In-situ electrochemical coating of Ag nanoparticles onto graphite electrode with enhanced performance for Li-ion batteries

    International Nuclear Information System (INIS)

    Yun, Jiaojiao; Wang, Yan; Gao, Tian; Zheng, Huiyuan; Shen, Ming; Qu, Qunting; Zheng, Honghe

    2015-01-01

    The effects of silver hexafluorophosphate (AgPF 6 ) as an electrolyte additive on the electrochemical behaviors of graphite anode are systematically studied by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The surface structure and composition of graphite electrode after electrochemical cycles are investigated through scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. It is found that Ag nanoparticles derived from electrochemical reduction of Ag + are homogenously distributed on the graphite surface. Significant improvements on the discharge capacity, rate behavior, and low-temperature performance of graphite electrode are obtained. The reasons are associated with the decreased resistances of solid-electrolyte interface and charge-transfer process, which improve the electrode kinetics for Li + intercalation/deintercalation

  7. Electrochemical sensing carcinogens in beverages

    CERN Document Server

    Zia, Asif Iqbal

    2016-01-01

    This book describes a robust, low-cost electrochemical sensing system that is able to detect hormones and phthalates – the most ubiquitous endocrine disruptor compounds – in beverages and is sufficiently flexible to be readily coupled with any existing chemical or biochemical sensing system. A novel type of silicon substrate-based smart interdigital transducer, developed using MEMS semiconductor fabrication technology, is employed in conjunction with electrochemical impedance spectroscopy to allow real-time detection and analysis. Furthermore, the presented interdigital capacitive sensor design offers a sufficient penetration depth of the fringing electric field to permit bulk sample testing. The authors address all aspects of the development of the system and fully explain its benefits. The book will be of wide interest to engineers, scientists, and researchers working in the fields of physical electrochemistry and biochemistry at the undergraduate, postgraduate, and research levels. It will also be high...

  8. Electrochemical treatment of liquid wastes

    International Nuclear Information System (INIS)

    Hobbs, D.

    1996-01-01

    Electrochemical treatment processes are being evaluated and developed for the destruction of organic compounds and nitrates/nitrites and the removal of other hazardous species from liquid wastes stored throughout the DOE complex. This activity consists of five major tasks: (1) evaluation of different electrochemical reactors for the destruction and removal of hazardous waste components, (2) development and validation of engineering process models, (3) radioactive laboratory-scale tests, (4) demonstration of the technology in an engineering-scale size reactor, and (5) analysis and evaluation of testing data. The development program team is comprised of individuals from federal, academic, and private industry. Work is being carried out in DOE, academic, and private industrial laboratories

  9. Recent Advances in Electrochemical Glycobiosensing

    Directory of Open Access Journals (Sweden)

    Germarie Sánchez-Pomales

    2011-01-01

    Full Text Available Biosensors based on electrochemical transduction mechanisms have recently made advances into the field of glycan analysis. These glyco-biosensors offer simple, rapid, sensitive, and economical approaches to the measurement need for rapid glycan analysis for biomarker detection, cancer and disease diagnostics, and bioprocess monitoring of therapeutic glycoproteins. Although the prevalent methods of glycan analysis (high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy provide detailed identification and structural analysis of glycan species, there are significantly few low-cost, rapid glycan assays available for diagnostic and screening applications. Here we review instances in which glyco-biosensors have been used for glycan analysis using a variety of electrochemical transduction mechanisms (e.g., amperometric, potentiometric, impedimetric, and voltammetric, selective binding agents (e.g., lectins and antibodies, and redox species (e.g., enzyme substrates, inorganic, and nanomaterial.

  10. Electrochemical fabrication of a novel conducting metallopolymer nanoparticles and its electrocatalytic application

    International Nuclear Information System (INIS)

    Kazemi, Sayed Habib; Mohamadi, Rahim

    2013-01-01

    Graphical abstract: Nanoparticles of nickel-curcumin conducting polymer (Ni-Curc-NPs) were fabricated by a two steps electrochemical method. In the first step, nickel source was immobilized at the electrode surface in the form of nickel nanoparticles (NiNPs). Then, electropolymerization of Ni-curcumin was performed at the NiNPs modified electrode. These nanostructures were successfully employed for electrooxidative determination of glucose and significant increase in the electrochemical sensitivity and lower limit of detection were observed. -- Highlights: • A novel two steps method for fabrication of nickel-curcumin conducting polymer was described. • Nickel-curcumine nanoparticles were easily prepared instead of thin film. • Ni-Curc-NPs modified electrode was successfully employed for electrooxidation of glucose. • Significant improvement in the sensitivity and limit of detection was observed. -- Abstract: Present article is the first example of a novel two step electrochemical route for fabrication of nanoparticles of conducting metallopolymer of Ni-curcumin (Ni-Curc-NPs). Firstly, nickel nanoparticles (Ni-NPs) were electrochemically deposited on the electrode surface. Then, electropolymerization of Ni-Curc-NPs were performed at the electrode modified with Ni-NPs. These nanostructures were characterized using electrochemical methods including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and hydrodynamic amperometry, also surface analysis methods and electron microscopy including energy dispersive analysis of X-ray (EDAX), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Additionally, application of the Ni-Curc-NPs modified electrode toward glucose electrooxidation was examined. A lower limit of detection and enhanced dynamic linear range for determination of glucose were observed at Ni-Curc-NPs modified electrode compared to Ni-NPs modified electrode

  11. Electrochemical Applications in Metal Bioleaching.

    Science.gov (United States)

    Tanne, Christoph Kurt; Schippers, Axel

    2017-12-10

    Biohydrometallurgy comprises the recovery of metals by biologically catalyzed metal dissolution from solids in an aqueous solution. The application of this kind of bioprocessing is described as "biomining," referring to either bioleaching or biooxidation of sulfide metal ores. Acidophilic iron- and sulfur-oxidizing microorganisms are the key to successful biomining. However, minerals such as primary copper sulfides are recalcitrant to dissolution, which is probably due to their semiconductivity or passivation effects, resulting in low reaction rates. Thus, further improvements of the bioleaching process are recommendable. Mineral sulfide dissolution is based on redox reactions and can be accomplished by electrochemical technologies. The impact of electrochemistry on biohydrometallurgy affects processing as well as analytics. Electroanalysis is still the most widely used electrochemical application in mineralogical research. Electrochemical processing can contribute to bioleaching in two ways. The first approach is the coupling of a mineral sulfide to a galvanic partner or electrocatalyst (spontaneous electron transfer). This approach requires only low energy consumption and takes place without technical installations by the addition of higher redox potential minerals (mostly pyrite), carbonic material, or electrocatalytic ions (mostly silver ions). Consequently, the processed mineral (often chalcopyrite) is preferentially dissolved. The second approach is the application of electrolytic bioreactors (controlled electron transfer). The electrochemical regulation of electrolyte properties by such reactors has found most consideration. It implies the regulation of ferrous and ferric ion ratios, which further results in optimized solution redox potential, less passivation effects, and promotion of microbial activity. However, many questions remain open and it is recommended that reactor and electrode designs are improved, with the aim of finding options for simplified

  12. Composite Electrodes for Electrochemical Supercapacitors

    OpenAIRE

    Li, Jun; Yang, QuanMin; Zhitomirsky, Igor

    2010-01-01

    Abstract Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4–6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT) into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with to...

  13. Electrochemical studies of ruthenium compounds

    International Nuclear Information System (INIS)

    Kumar Ghosh, B.; Chakravorty, A.

    1989-01-01

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

  14. Neutron dosimetry using electrochemical etching

    International Nuclear Information System (INIS)

    Su, S.J.; Stillwagon, G.B.; Morgan, K.Z.

    1977-01-01

    Registration of α-tracks and fast-neutron-induced recoils tracks by the electrochemical etching technique as applied to sensitive polymer foils (e.g., polycarbonate) provides a simple, sensitive and inexpensive means of fast neutron personnel dosimetry as well as a valuable research tool for microdosimetry. When tracks were amplified by our electrochemical technique and the etching results compared with conventional etching technique a striking difference was noted. The electrochemically etched tracks were of much larger diameter (approx. 100 μm) and gave superior contrast. Two optical devices--the transparency projector and microfiche reader--were adapted to facilitate counting of the tracks appearing on our polycarbonate foils. The projector produced a magnification of 14X for a screen to projector distance of 5.0 meter and read's magnification was 50X. A Poisson distribution was determined for the number of tracks located in a particular area of the foil and experimentally verified by random counting of quarter sections of the microfiche reader screen. Finally, in an effort to determine dose equivalent (rem), a conversion factor is being determined by finding the sensitivity response (tracks/neutron) of recoil particle induced tracks as a function of monoenergetic fast neutrons and comparing results with those obtained by others

  15. Facile electrochemical synthesis of few layered graphene from discharged battery electrode and its

    Directory of Open Access Journals (Sweden)

    Santosh K. Tiwari

    2017-05-01

    Full Text Available A cost-effective, simple and non-hazardous route for synthesis of few-layered graphene from waste zinc carbon battery (ZCB electrodes via electrochemical expansion (ECE has been reported. In this synthesis, we have electrochemically exfoliated the graphene layers, by intercalating sodium dodecyl benzenesulfonate (SDBS surfactant into graphitic layers at different D.C. voltages with a constant SDBS concentration. The graphene sheets were isolated, purified and characterized by Transmission electron microscopy (TEM, Scanning electron microscopy (SEM, Fourier transform infrared spectrometry (FTIR, X-ray diffraction (XRD, Raman spectrometry, Ultraviolet absorption (UV, Selected area electron diffraction (SAED and Cyclic voltammetry. Best result was obtained at 4.5 V of D.C. A possible mechanism for the intercalation process has been proposed. A promising application of the produced material for supercapacitor application has also been explored in combination with polyaniline.

  16. One step paired electrochemical synthesis of iron and iron oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Ordoukhanian Juliet

    2016-09-01

    Full Text Available In this study, a new one step paired electrochemical method is developed for simultaneous synthesis of iron and iron oxide nanoparticles. iron and iron oxide are prepared as cathodic and anodic products from iron (ii sulfate aqueous solution in a membrane divided electrolytic cell by the pulsed current electrosynthesis. Because of organic solvent-free and electrochemical nature of the synthesis, the process could be considered as green and environmentally friendly. The reduction of energy consumption and low cost are the other significant advantages of this new method that would have a great application potential in the chemical industry. The nanostructure of prepared samples was characterized by Fourier transform infrared spectroscopy (FT-IR, X-ray diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The magnetic properties were studied by vibrating sample magnetometer (VsM.

  17. Microscopy techniques in flavivirus research.

    Science.gov (United States)

    Chong, Mun Keat; Chua, Anthony Jin Shun; Tan, Terence Tze Tong; Tan, Suat Hoon; Ng, Mah Lee

    2014-04-01

    The Flavivirus genus is composed of many medically important viruses that cause high morbidity and mortality, which include Dengue and West Nile viruses. Various molecular and biochemical techniques have been developed in the endeavour to study flaviviruses. However, microscopy techniques still have irreplaceable roles in the identification of novel virus pathogens and characterization of morphological changes in virus-infected cells. Fluorescence microscopy contributes greatly in understanding the fundamental viral protein localizations and virus-host protein interactions during infection. Electron microscopy remains the gold standard for visualizing ultra-structural features of virus particles and infected cells. New imaging techniques and combinatory applications are continuously being developed to push the limit of resolution and extract more quantitative data. Currently, correlative live cell imaging and high resolution three-dimensional imaging have already been achieved through the tandem use of optical and electron microscopy in analyzing biological specimens. Microscopy techniques are also used to measure protein binding affinities and determine the mobility pattern of proteins in cells. This chapter will consolidate on the applications of various well-established microscopy techniques in flavivirus research, and discuss how recently developed microscopy techniques can potentially help advance our understanding in these membrane viruses. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Passivation Dynamics in the Anisotropic Deposition and Stripping of Bulk Magnesium Electrodes During Electrochemical Cycling.

    Science.gov (United States)

    Wetzel, David J; Malone, Marvin A; Haasch, Richard T; Meng, Yifei; Vieker, Henning; Hahn, Nathan T; Gölzhäuser, Armin; Zuo, Jian-Min; Zavadil, Kevin R; Gewirth, Andrew A; Nuzzo, Ralph G

    2015-08-26

    Although rechargeable magnesium (Mg) batteries show promise for use as a next generation technology for high-density energy storage, little is known about the Mg anode solid electrolyte interphase and its implications for the performance and durability of a Mg-based battery. We explore in this report passivation effects engendered during the electrochemical cycling of a bulk Mg anode, characterizing their influences during metal deposition and dissolution in a simple, nonaqueous, Grignard electrolyte solution (ethylmagnesium bromide, EtMgBr, in tetrahydrofuran). Scanning electron microscopy images of Mg foil working electrodes after electrochemical polarization to dissolution potentials show the formation of corrosion pits. The pit densities so evidenced are markedly potential-dependent. When the Mg working electrode is cycled both potentiostatically and galvanostatically in EtMgBr these pits, formed due to passive layer breakdown, act as the foci for subsequent electrochemical activity. Detailed microscopy, diffraction, and spectroscopic data show that further passivation and corrosion results in the anisotropic stripping of the Mg {0001} plane, leaving thin oxide-comprising passivated side wall structures that demark the {0001} fiber texture of the etched Mg grains. Upon long-term cycling, oxide side walls formed due to the pronounced crystallographic anisotropy of the anodic stripping processes, leading to complex overlay anisotropic, columnar structures, exceeding 50 μm in height. The passive responses mediating the growth of these structures appear to be an intrinsic feature of the electrochemical growth and dissolution of Mg using this electrolyte.

  19. Effect of black clay soil moisture on the electrochemical behavior of API X70 pipeline steel

    Science.gov (United States)

    Hendi, R.; Saifi, H.; Belmokre, K.; Ouadah, M.; Smili, B.; Talhi, B.

    2018-03-01

    The effect of moisture content variation (20–100 wt.%) on the electrochemical behavior of API X70 pipeline steel buried in the soil of Skikda (East of Algeria) was studied using electrochemical techniques, scanning electron microscopy (SEM), X ray diffraction analysis (XRD) and weight loss measurement. The electrochemical measurements showed that the corrosion current Icorr is directly proportional to the moisture content up to 50 wt.%, beyond this content, this value becomes almost constant. The result were confirmed by electrochemical impedance spectroscopy; the capacitance of the double layer formed on the surface is the highest at 50 wt.%. A single time constant was detected by plotting the Bode diagrams. The steel surface degradation has been appreciated using the scanning electron microscopy observations. A few pitting corrosion at 20 wt.% moisture, followed by more degradation at 50 wt.% have been revealed. However, when the moisture amount exceeded 50 wt.%, the surface became entirely covered by a corrosion product. XRD analysis revealed the dominance of FeOOH and Fe3O4 phases on steel surface for a moisture content of 50 wt.%.

  20. Effect of preparation methods on dispersion stability and electrochemical performance of graphene sheets

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Li, E-mail: chenli1981@lut.cn; Li, Na; Zhang, Mingxia; Li, Pinnan; Lin, Zhengping

    2017-05-15

    Chemical exfoliation is one of the most important strategies for preparing graphene. The aggregation of graphene sheets severely prevents graphene from exhibiting excellent properties. However, there are no attempts to investigate the effect of preparation methods on the dispersity of graphene sheets. In this study, three chemical exfoliation methods, including Hummers method, modified Hummers method, and improved method, were used to prepare graphene sheets. The influence of preparation methods on the structure, dispersion stability in organic solvents, and electrochemical properties of graphene sheets were investigated. Fourier transform infrared microscopy, Raman spectra, transmission electron microscopy, and UV–vis spectrophotometry were employed to analyze the structure of the as-prepared graphene sheets. The results showed that graphene prepared by improved method exhibits excellent dispersity and stability in organic solvents without any additional stabilizer or modifier, which is attributed to the completely exfoliation and regular structure. Moreover, cyclic voltammetric and electrochemical impedance spectroscopy measurements showed that graphene prepared by improved method exhibits superior electrochemical properties than that prepared by the other two methods. - Graphical abstract: Graphene oxides with different oxidation degree were obtained via three methods, and then graphene with different crystal structures were created by chemical reduction of exfoliated graphene oxides. - Highlights: • Graphene oxides with different oxidation degree were obtained via three oxidation methods. • The influence of oxidation methods on microstructure of graphene was investigated. • The effect of oxidation methods on dispersion stability of graphene was investigated. • The effect of oxidation methods on electrochemical properties of graphene was discussed.

  1. Effect of preparation methods on dispersion stability and electrochemical performance of graphene sheets

    International Nuclear Information System (INIS)

    Chen, Li; Li, Na; Zhang, Mingxia; Li, Pinnan; Lin, Zhengping

    2017-01-01

    Chemical exfoliation is one of the most important strategies for preparing graphene. The aggregation of graphene sheets severely prevents graphene from exhibiting excellent properties. However, there are no attempts to investigate the effect of preparation methods on the dispersity of graphene sheets. In this study, three chemical exfoliation methods, including Hummers method, modified Hummers method, and improved method, were used to prepare graphene sheets. The influence of preparation methods on the structure, dispersion stability in organic solvents, and electrochemical properties of graphene sheets were investigated. Fourier transform infrared microscopy, Raman spectra, transmission electron microscopy, and UV–vis spectrophotometry were employed to analyze the structure of the as-prepared graphene sheets. The results showed that graphene prepared by improved method exhibits excellent dispersity and stability in organic solvents without any additional stabilizer or modifier, which is attributed to the completely exfoliation and regular structure. Moreover, cyclic voltammetric and electrochemical impedance spectroscopy measurements showed that graphene prepared by improved method exhibits superior electrochemical properties than that prepared by the other two methods. - Graphical abstract: Graphene oxides with different oxidation degree were obtained via three methods, and then graphene with different crystal structures were created by chemical reduction of exfoliated graphene oxides. - Highlights: • Graphene oxides with different oxidation degree were obtained via three oxidation methods. • The influence of oxidation methods on microstructure of graphene was investigated. • The effect of oxidation methods on dispersion stability of graphene was investigated. • The effect of oxidation methods on electrochemical properties of graphene was discussed.

  2. Fluorescence confocal microscopy for pathologists.

    Science.gov (United States)

    Ragazzi, Moira; Piana, Simonetta; Longo, Caterina; Castagnetti, Fabio; Foroni, Monica; Ferrari, Guglielmo; Gardini, Giorgio; Pellacani, Giovanni

    2014-03-01

    Confocal microscopy is a non-invasive method of optical imaging that may provide microscopic images of untreated tissue that correspond almost perfectly to hematoxylin- and eosin-stained slides. Nowadays, following two confocal imaging systems are available: (1) reflectance confocal microscopy, based on the natural differences in refractive indices of subcellular structures within the tissues; (2) fluorescence confocal microscopy, based on the use of fluorochromes, such as acridine orange, to increase the contrast epithelium-stroma. In clinical practice to date, confocal microscopy has been used with the goal of obviating the need for excision biopsies, thereby reducing the need for pathological examination. The aim of our study was to test fluorescence confocal microscopy on different types of surgical specimens, specifically breast, lymph node, thyroid, and colon. The confocal images were correlated to the corresponding histological sections in order to provide a morphologic parallel and to highlight current limitations and possible applications of this technology for surgical pathology practice. As a result, neoplastic tissues were easily distinguishable from normal structures and reactive processes such as fibrosis; the use of fluorescence enhanced contrast and image quality in confocal microscopy without compromising final histologic evaluation. Finally, the fluorescence confocal microscopy images of the adipose tissue were as accurate as those of conventional histology and were devoid of the frozen-section-related artefacts that can compromise intraoperative evaluation. Despite some limitations mainly related to black/white images, which require training in imaging interpretation, this study confirms that fluorescence confocal microscopy may represent an alternative to frozen sections in the assessment of margin status in selected settings or when the conservation of the specimen is crucial. This is the first study to employ fluorescent confocal microscopy on

  3. Electrochemical Positioning of Ordered Nanostructures

    Science.gov (United States)

    2016-04-26

    capable of both, AFM and STM ( scanning tunneling microscopy). The AFM system delivers low drift and low noise that is perfect for our laboratory...STM ( scanning tunneling microscopy). The AFM system delivers low drift and low noise that is perfect for our laboratory which is on the second...Force Microscope (AFM). Using this equipment, faculty and students will seek to explore two questions, (1) “What are some of the changes in the

  4. Fabrication and electrochemical behavior of single-walled carbon nanotube/graphite-based electrode

    International Nuclear Information System (INIS)

    Moghaddam, Abdolmajid Bayandori; Ganjali, Mohammad Reza; Dinarvand, Rassoul; Razavi, Taherehsadat; Riahi, Siavash; Rezaei-Zarchi, Saeed; Norouzi, Parviz

    2009-01-01

    An electrochemical method for determining the dihydroxybenzene derivatives on glassy carbon (GC) has been developed. In this method, the performance of a single-walled carbon nanotube (SWCNT)/graphite-based electrode, prepared by mixing SWCNTs and graphite powder, was described. The resulting electrode shows an excellent behavior for redox of 3,4-dihydroxybenzoic acid (DBA). SWCNT/graphite-based electrode presents a significant decrease in the overvoltage for DBA oxidation as well as a dramatic improvement in the reversibility of DBA redox behavior in comparison with graphite-based and glassy carbon (GC) electrodes. In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) procedures performed for used SWCNTs

  5. Novel Electrochemical Synthesis of Polypyrrole/Ag Nanocomposite and Its Electrocatalytic Performance towards Hydrogen Peroxide Reduction

    OpenAIRE

    Ruma Gupta; Kavitha Jayachandran; J. S. Gamare; B. Rajeshwari; Santosh K. Gupta; J. V. Kamat

    2015-01-01

    A simple electrochemical method of synthesis of polypyrrole/silver (PPy/Ag) nanocomposite is presented. The method is based on potentiodynamic polymerization of pyrrole followed by electrodeposition of silver employing a single potentiostatic pulse. The synthesized PPy film has embedded Ag nanocubes. The morphology and structure of the resulting nanocomposite were characterized by field emission scanning electron microscopy and X-ray diffraction. Electron paramagnetic resonance studies showed...

  6. Characterization by acoustic emission and electrochemical impedance spectroscopy of the cathodic disbonding of Zn coating

    International Nuclear Information System (INIS)

    Amami, Souhail; Lemaitre, Christian; Laksimi, Abdelouahed; Benmedakhene, Salim

    2010-01-01

    Galvanized steel has been tested in a synthetic sea water solution under different cathodic overprotection conditions. The generated hydrogen flux caused the damage of the metal-zinc interface and led to a progressive coating detachment. Scanning electron microscopy, electrochemical impedance spectroscopy and acoustic emission technique were used to characterize the damage chronology under different cathodic potentials. A damage mechanism was proposed and the acoustic signature related to the coating degradation was statistically identified using clustering techniques.

  7. Characterization by acoustic emission and electrochemical impedance spectroscopy of the cathodic disbonding of Zn coating

    Energy Technology Data Exchange (ETDEWEB)

    Amami, Souhail [Universite de Technologie de Compiegne, Departement de Genie Mecanique, Laboratoire Roberval, UMR 6066 du CNRS, B.P. 20529, 60206 Compiegne Cedex (France)], E-mail: souhail.amami@utc.fr; Lemaitre, Christian; Laksimi, Abdelouahed; Benmedakhene, Salim [Universite de Technologie de Compiegne, Departement de Genie Mecanique, Laboratoire Roberval, UMR 6066 du CNRS, B.P. 20529, 60206 Compiegne Cedex (France)

    2010-05-15

    Galvanized steel has been tested in a synthetic sea water solution under different cathodic overprotection conditions. The generated hydrogen flux caused the damage of the metal-zinc interface and led to a progressive coating detachment. Scanning electron microscopy, electrochemical impedance spectroscopy and acoustic emission technique were used to characterize the damage chronology under different cathodic potentials. A damage mechanism was proposed and the acoustic signature related to the coating degradation was statistically identified using clustering techniques.

  8. Electrochemical synthesis of polypyrrole on ferrous and non-ferrous metals from sweet aqueous electrolytic medium

    International Nuclear Information System (INIS)

    Bazzaoui, M.; Martins, J.I.; Reis, T.C.; Bazzaoui, E.A.; Nunes, M.C.; Martins, L.

    2005-01-01

    The electrodeposition of polypyrrole (PPy) on oxidizable metals such as aluminum and iron has been achieved in aqueous medium of saccharin and pyrrole. Scanning electron microscopy and X-ray photoelectron spectroscopy analysis reveal a good homogeneity of the obtained PPy film. The electrochemical synthesis of PPy coating has been achieved successfully under potentiodynamic, galvanostatic and potentiostatic techniques. The corrosion experiments performed in HCl show that the PPy coating increases the corrosion potential and decreases the corrosion current density

  9. Kinetic mechanism for modeling of electrochemical reactions.

    Science.gov (United States)

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

    2012-04-01

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

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

    Science.gov (United States)

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

    2013-01-11

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

  11. Applications of Nonlinear Electrochemical Impedance Spectroscopy (NLEIS)

    KAUST Repository

    Adler, S. B.

    2013-08-31

    This paper reviews the use of nonlinear electrochemical impedance spectroscopy (NLEIS) in the analysis of SOFC electrode reactions. By combining EIS and NLEIS, as well as other independent information about an electrode material, it becomes possible to establish quantitative links between electrochemical kinetics and materials properties, even when systems are unstable with time. After a brief review of the method, this paper summarizes recent results analyzing the effects of Sr segregation in thin-film LSC electrodes. © The Electrochemical Society.

  12. Fabrication of Micro Components by Electrochemical Deposition

    DEFF Research Database (Denmark)

    Tang, Peter Torben

    The main issue of this thesis is the combination of electrochemical deposition of metals and micro machining. Processes for electroplating and electroless plating of nickel and nickel alloys have been developed and optimised for compatibility with microelectronics and silicon based micromechanics...... of electrochemical machining and traditional machining is compared to micro machining techniques as performed in the field of microelectronics. Various practical solutions and equipment for electrochemical deposition of micro components are demonstrated, as well as the use and experience obtained utilising...

  13. Management of processes of electrochemical dimensional processing

    Science.gov (United States)

    Akhmetov, I. D.; Zakirova, A. R.; Sadykov, Z. B.

    2017-09-01

    In different industries a lot high-precision parts are produced from hard-processed scarce materials. Forming such details can only be acting during non-contact processing, or a minimum of effort, and doable by the use, for example, of electro-chemical processing. At the present stage of development of metal working processes are important management issues electrochemical machining and its automation. This article provides some indicators and factors of electrochemical machining process.

  14. Electrochemical ion separation in molten salts

    Science.gov (United States)

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

    2017-12-19

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

  15. Studying the Kinetics of Crystalline Silicon Nanoparticle Lithiation with In Situ Transmission Electron Microscopy

    KAUST Repository

    McDowell, Matthew T.

    2012-09-04

    In situ transmission electron microscopy (TEM) is used to study the electrochemical lithiation of high-capacity crystalline Si nanoparticles for use in Li-ion battery anodes. The lithiation reaction slows down as it progresses into the particle interior, and analysis suggests that this behavior is due not to diffusion limitation but instead to the influence of mechanical stress on the driving force for reaction. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Studying the Kinetics of Crystalline Silicon Nanoparticle Lithiation with In Situ Transmission Electron Microscopy

    KAUST Repository

    McDowell, Matthew T.; Ryu, Ill; Lee, Seok Woo; Wang, Chongmin; Nix, William D.; Cui, Yi

    2012-01-01

    In situ transmission electron microscopy (TEM) is used to study the electrochemical lithiation of high-capacity crystalline Si nanoparticles for use in Li-ion battery anodes. The lithiation reaction slows down as it progresses into the particle interior, and analysis suggests that this behavior is due not to diffusion limitation but instead to the influence of mechanical stress on the driving force for reaction. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. 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

  18. V2O5 xerogel-poly(ethylene oxide) hybrid material: Synthesis, characterization, and electrochemical properties

    International Nuclear Information System (INIS)

    Guerra, Elidia M.; Ciuffi, Katia J.; Oliveira, Herenilton P.

    2006-01-01

    In this work, we report the synthesis, characterization, and electrochemical properties of vanadium pentoxide xerogel-poly(ethylene oxide) (PEO) hybrid materials obtained by varying the average molecular weight of the organic component as well as the components' ratios. The materials were characterized by X-ray diffraction, ultraviolet/visible and infrared spectroscopies, thermogravimetric analysis, scanning electron microscopy, electron paramagnetic resonance, and cyclic voltammetry. Despite the presence of broad and low intensity peaks, the X-ray diffractograms indicate that the lamellar structure of the vanadium pentoxide xerogel is preserved, with increase in the interplanar spacing, giving evidence of a low-crystalline structure. We found that the electrochemical behaviour of the hybrid materials is quite similar to that found for the V 2 O 5 xerogel alone, and we verified that PEO leads to stabilization and reproducibility of the Li + electrochemical insertion/de-insertion into the V 2 O 5 xerogel structure, which makes these materials potential components of lithium ion batteries. - Graphical abstract: The synthesis, structural and electrochemical properties of vanadium pentoxide xerogel-poly(ethylene oxide) hybrid materials have been described. Despite the presence of broad and low intensity peaks, the X-ray diffractograms indicate that the lamellar structure of the vanadium pentoxide xerogel is preserved. The cyclic voltammetry technique demonstrated that PEO intercalation provides an improvement in the electrochemical properties, mainly with respect to the lithium electroinsertion process into the oxide matrix

  19. Electrochemical behavior of cysteine at a CuGeO3 nanowires modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Dong Yongping; Pei Lizhai; Chu Xiangfeng; Zhang Wangbing; Zhang Qianfeng

    2010-01-01

    A CuGeO 3 nanowire modified glassy carbon electrode was fabricated and characterized by scanning electron microscopy. The results of electrochemical impedance spectroscopy reveal that electron transfer through nanowire film is facile compared with that of bare glassy carbon electrode. The modified electrode exhibited a novel electrocatalytic behavior to the electrochemical reactions of L-cysteine in neutral solution, which was not reported previously. Two pairs of semi-reversible electrochemical peaks were observed and assigned to the processes of oxidation/reduction and adsorption/desorption of cysteine at the modified electrode, respectively. The electrochemical response of cysteine is poor in alkaline condition and is enhanced greatly in acidic solution, suggesting that hydrogen ions participate in the electrochemical oxidation process of cysteine. The intensities of two anodic peaks varied linearly with the concentration of cysteine in the range of 1 x 10 -6 to 1 x 10 -3 mol L -1 , which make it possible to sensitive detection of cysteine with the CuGeO 3 nanowire modified electrode. Furthermore, the modified electrode exhibited good reproducibility and stability.

  20. Chitosan/graphene oxide nanocomposite films with enhanced interfacial interaction and their electrochemical applications

    International Nuclear Information System (INIS)

    He, Linghao; Wang, Hongfang; Xia, Guangmei; Sun, Jing; Song, Rui

    2014-01-01

    Graphical abstract: Nanocomposites by introducing graphene oxide (GO) into chitosan (CS) matrix were prepared and the effect of GO on the crystallization, thermal stability and mechanical properties of the films were investigated. In addition, the electrochemical behavior of the CS/GO modified electrode was comparatively studied with that of the neat CS-modified electrode. - Highlights: • Graphene oxide (GO) with well dispersion in the biopolymer chitosan (CS) matrix. • Detectable interactions do exist between the GO nanosheets and CS segments. • The addition of minor GO can improve the electrochemical activity of the neat CS. - Abstract: A series of chitosan (CS) nanocomposites incorporated with graphene oxide (GO) nanosheets were facilely prepared by sonochemical method. Characterized by scanning electron microscopy, the obtained nanocomposites showed fine dispersion of GO in the CS matrix. Meanwhile, a marked interfacial interaction was also revealed as the values of glass transition temperature, the decomposition temperature and the storage modulus were significantly increased with the addition of GO. Furthermore, the well dispersed GO nanosheets could significantly improve the electrochemical activity of the CS as demonstrated by the electrochemical behaviors of pure CS and the GO/CS composite electrodes. Hence, the GO/CS nanocomposites film could be a promising candidate in the fabrication of electrochemical biosensors

  1. On the possibility of electrochemical unzipping of multiwalled carbon nanotubes to produce graphene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Zehtab Yazdi, Alireza; Roberts, Edward P.L.; Sundararaj, Uttandaraman, E-mail: u.sundararaj@ucalgary.ca

    2016-08-15

    Highlights: • MWCNTs synthesized and electrochemically oxidized to study the formation of GNR • HRTEM, Raman and XPS confirmed no successful unzipping occurred after oxidation • Electrochemical oxidation very unlikely facilitate formation of intercalated MWCNTs - Abstract: Multiwalled carbon nanotubes (MWCNTs) with different geometrical characteristics and chemical doping have been synthesized and electrochemically oxidized to study the possibility of unzipping, and creating graphene nanoribbon (GNR) nanostructures. Modified glassy carbon electrodes of the MWCNTs have been tested in an aqueous electrolyte via anodic scans in a wide range of potentials, followed by keeping at the maximum potential for different times. The microstructural features, structural defects, and functional groups and their elements have been then studied using high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. All results have confirmed that no successful unzipping occurs in the MWCNTs after electrochemical oxidation, even for the nitrogen-doped MWCNTs (CN{sub x}-MWCNTs) with reactive nitrogen groups and defective bamboo structures. In contrast to the report by Shinde et al. (J. Am. Chem. Soc. 2011, 133, 4168–4171), it has been concluded that the electrochemical oxidation in aqueous electrolytes is very unlikely to facilitate sufficient incorporation of the intercalated molecules among the walls of the MWCNTs. These molecules are, however, responsible for unzipping of MWCNTs.

  2. Polypyrrole Composite Film for Highly Sensitive and Selective Electrochemical Determination Sensors

    International Nuclear Information System (INIS)

    Zheng, Xiangli; Tian, Dong; Duan, Shuo; Wei, Maochao; Liu, Shan; Zhou, Changli; Li, Qing; Wu, Gang

    2014-01-01

    In this paper, polypyrrole (PPy) and benz[a]anthracene-7,12-dione (BaD) were electro-polymerized onto a pyrolytic graphite electrode (PGE), constructing a novel BaD/PPy/PGE platform for electrochemical sensoring. The morphology and electrochemical properties of the fabricated BaD/PPy/PGE were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Furthermore, the electrochemical behavior of benzo[k]fluoranthene (BkF) at the BaD/PPy/PGE was investigated. Due to the specific interactions between BkF and BaD, a wide linear range of BkF detection from 1.0 × 10 −12 to 1.0 × 10 −9 M with good linearity (R 2 = 0.9962) and a low detection limit (1.0 × 10 −13 M, S/N = 3) were demonstrated. Importantly, other similar aromatics which had one ring or more than two rings, such as benzo[a]anthracene, benzo[a]pyrene, pyrene, benzo[ghi]peryle, anthracene, phenanthrene, naphthalene and parachlorophenol, showed insignificant interference on BkF detection. Consequently, this novel BaD/PPy/PGE with excellent stability and selectivity holds promise as an effective BkF electrochemical sensor in aqueous solution. As an example for its practical application, the newly developed sensor was applied to quantitative determination of BkF in waste water samples obtained from a coking plant with satisfactory sensitivity, selectivity, and reversibility

  3. Scanning Tunneling Microscopy - image interpretation

    International Nuclear Information System (INIS)

    Maca, F.

    1998-01-01

    The basic ideas of image interpretation in Scanning Tunneling Microscopy are presented using simple quantum-mechanical models and supplied with examples of successful application. The importance is stressed of a correct interpretation of this brilliant experimental surface technique

  4. Graphene Nanosheets/Poly(3,4-ethylenedioxythiophene) Nanotubes Composite Materials for Electrochemical Biosensing Applications

    International Nuclear Information System (INIS)

    Huang, Tzu-Yen; Kung, Chung-Wei; Wang, Jen-Yuan; Lee, Min-Han; Chen, Lin-Chi; Chu, Chih-Wei; Ho, Kuo-Chuan

    2015-01-01

    Highlights: • Novel composite materials contain 2D rGO nanosheets and 1D PEDOT nanotubes. • 3D nanocomposite film effectively improved the sensitivity for analyte detection. • The rGO/PEDOT NTs film shows good catalytic activities toward hydrazine and H 2 O 2 . • The rGO/PEDOT NTs film also exhibits high selectivity from the interference test. -- Graphical abstract: Display Omitted -- Abstract: In this study, we developed the novel composite materials containing reduced graphene oxide (rGO) nanosheets and poly(3,4-ethylenedioxythiophene) nanotubes (PEDOT NTs) for electrochemical biosensing applications. Transmission electron microscopy, scanning electron microscopy and atomic force microscopy suggested that the rGO nanosheets cover the substrate uniformly, and the PEDOT NTs act as a conducting bridge to connect the rGO sheets. By combining the two materials, it's expected to enhance the conductivity of the film and improve the surface coverage. We applied the rGO/PEDOT NTs composite for electrochemical detection of hydrazine and hydrogen peroxide; noticeable improvements in electrochemical activity and reactivity were observed compared to those of the pristine rGO and PEDOT NTs electrodes. This may be attributed to the better surface coverage of the rGO/PEDOT NTs modified electrode with superior conductivity. Furthermore, interference tests indicate that the rGO/PEDOT NTs composite film exhibits high selectivity toward the analyte. The rGO/PEDOT NTs composite thus provides a potential platform for biosensing applications

  5. Graphene-Paper Based Electrochemical Sensors

    DEFF Research Database (Denmark)

    Zhang, Minwei; Halder, Arnab; Cao, Xianyi

    2017-01-01

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

  6. Electrochemical modeling of hydrogen storage in hydride-forming electrodes

    NARCIS (Netherlands)

    Ledovskikh, A.; Danilov, D.; Vermeulen, P.; Notten, P.H.L.

    2009-01-01

    An electrochemical kinetic model (EKM) is developed, describing the electrochemical hydrogen storage in hydride-forming materials under equilibrium conditions. This model is based on first principles of electrochemical reaction kinetics and statistical thermodynamics and describes the complex,

  7. Mediated electrochemical hazardous waste destruction

    International Nuclear Information System (INIS)

    Hickman, R.G.; Farmer, J.C.; Wang, F.T.

    1992-03-01

    There are few permitted processes for mixed waste (radioactive plus chemically hazardous) treatment. We are developing an electrochemical process, based upon mediated electrochemical oxidation (MEO), that converts toxic organic components of mixed waste to water, carbon dioxide, and chloride or chloride precipitates. Aggressive oxidizer ions such as Ag 2+ , Co 3+ , or Fe 3+ are produced at an anode. These can attack organic molecules directly, and may also produce hydroxyl free radicals that promote destruction. Solid and liquid radioactive waste streams containing only inorganic radionuclide forms may be treated with existing technology and prepared for final disposal. The coulombic efficiency of the process has been determined, as well as the destruction efficiency for ethylene glycol, a surrogate waste. In addition, hazardous organic materials are becoming very expensive to dispose of and when they are combined with transuranic radioactive elements no processes are presently permitted. Mediated electrochemical oxidation is an ambient- temperature aqueous-phase process that can be used to oxidize organic components of mixed wastes. Problems associated with incineration, such as high-temperature volatilization of radionuclides, are avoided. Historically, Ag(II) has been used as a mediator in this process. Fe(III) and Co(III) are attractive alternatives to Ag(II) since they form soluble chlorides during the destruction of chlorinated solvents. Furthermore, silver itself is toxic heavy metal. Quantitative data have been obtained for the complete oxidation of ethylene glycol by Fe(III) and Co(III). Though ethylene glycol is a nonhalogenated organic, these data have enabled us to make direct comparisons of activities of Fe(III) and Co(III) with Ag(II). Very good quantitative data for the oxidation of ethylene glycol by Ag(II) had already been collected

  8. Electrochemical properties of quaternary ammonium salts for electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Ue, Makoto; Takeda, Masayuki; Takehara, Masahiro; Mori, Shoichiro [Mitsubishi Chemical Corp., Inashiki, Ibaraki (Japan). Tsukuba Research Center

    1997-08-01

    The limiting reduction and oxidation potentials and electrolytic conductivities of new quaternary ammonium salts were examined for electrochemical capacitor applications, whose anions have already been tested as lithium salts for lithium battery applications. The anodic stability was in the following order BR{sub 4}{sup {minus}} < ClO{sub 4}{sup {minus}} {le} CF{sub 3}SO{sub 3}{sup {minus}} < (CF{sub 3}SO{sub 2}){sub 2}N{sup {minus}} {le} C{sub 4}F{sub 9}SO{sub 3}{sup {minus}} < BF{sub 4}{sup {minus}} < PF{sub 6}{sup {minus}} {le} AsF{sub 6}{sup {minus}} < SbF{sub 6}{sup {minus}}. The electrolytic conductivities of Me{sub 4{minus}n}Et{sub n}N(CF{sub 3}SO{sub 2}){sub 2}N (n = 0--4) were examined in comparison with Me{sub 4{minus}n}Et{sub n}NBF{sub 4} counterparts. These imide salts showed good solubility, relatively high conductivity, and anodic stability in propylene carbonate. Et{sub 4}N(CF{sub 3}SO{sub 2}){sub 2}N was found to be a good supporting salt for low permittivity organic solvents, and it afforded a highly conductive electrolyte system based on the ethylene carbonate-dimethyl carbonate mixed solvent, which is useful for electrochemical capacitor applications.

  9. Nanoporous carbon for electrochemical capacitors.

    Energy Technology Data Exchange (ETDEWEB)

    Siegal, Michael P.; Bunker, Bruce Conrad; Limmer, Steven J.; Yelton, William Graham

    2010-05-01

    Nanoporous carbon (NPC) is a purely graphitic material with highly controlled densities ranging from less than 0.1 to 2.0 g/cm3, grown via pulsed-laser deposition. Decreasing the density of NPC increases the interplanar spacing between graphene-sheet fragments. This ability to tune the interplanar spacing makes NPC an ideal model system to study the behavior of carbon electrodes in electrochemical capacitors and batteries. We examine the capacitance of NPC films in alkaline and acidic electrolytes, and measure specific capacitances as high as 242 F/g.

  10. Nanoelectrode array for electrochemical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yelton, William G [Sandia Park, NM; Siegal, Michael P [Albuquerque, NM

    2009-12-01

    A nanoelectrode array comprises a plurality of nanoelectrodes wherein the geometric dimensions of the electrode controls the electrochemical response, and the current density is independent of time. By combining a massive array of nanoelectrodes in parallel, the current signal can be amplified while still retaining the beneficial geometric advantages of nanoelectrodes. Such nanoelectrode arrays can be used in a sensor system for rapid, non-contaminating field analysis. For example, an array of suitably functionalized nanoelectrodes can be incorporated into a small, integrated sensor system that can identify many species rapidly and simultaneously under field conditions in high-resistivity water, without the need for chemical addition to increase conductivity.

  11. Nanoporous carbon for electrochemical capacitors.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Siegal, Michael P.; Bunker, Bruce Conrad; Limmer, Steven J.; Yelton, William Graham

    2010-04-01

    Nanoporous carbon (NPC) is a purely graphitic material with highly controlled densities ranging from less than 0.1 to 2.0 g/cm3, grown via pulsed-laser deposition. Decreasing the density of NPC increases the interplanar spacing between graphene-sheet fragments. This ability to tune the interplanar spacing makes NPC an ideal model system to study the behavior of carbon electrodes in electrochemical capacitors and batteries. We examine the capacitance of NPC films in alkaline and acidic electrolytes, and measure specific capacitances as high as 242 F/g.

  12. Electrochemical characterization of liquid resistors

    International Nuclear Information System (INIS)

    Wilson, J.M.; Whiteley, R.V.

    1983-01-01

    During the first two years of operation of Sandia's Particle Beam Fusion Accelerator (PBFA I) the reliability of the CuSO 4 solution resistors in the Marx Generator Energy Storage System has been unsatisfactory. Resistor failure, which is characterized by a large increase in resistance, has been attributed to materials, production techniques, and operating parameters. The problems associated with materials and production techniques have been identified and solutions are proposed. Non-ideal operating parameters are shown to cause polarization of the cathode in the resistor. This initiates electrochemical reactions in the resistor. These reactions often lead to resistance changes and to eventual resistor failure

  13. Lead-nickel electrochemical batteries

    CERN Document Server

    Glaize, Christian

    2012-01-01

    The lead-acid accumulator was introduced in the middle of the 19th Century, the diverse variants of nickel accumulators between the beginning and the end of the 20th Century. Although old, these technologies are always very present on numerous markets. Unfortunately they are still not used in optimal conditions, often because of the misunderstanding of the internal electrochemical phenomena.This book will show that batteries are complex systems, made commercially available thanks to considerable amounts of scientific research, empiricism and practical knowledge. However, the design of

  14. Preparation and characterization of zinc oxide nanoparticles and their sensor applications for electrochemical monitoring of nucleic acid hybridization.

    Science.gov (United States)

    Yumak, Tugrul; Kuralay, Filiz; Muti, Mihrican; Sinag, Ali; Erdem, Arzum; Abaci, Serdar

    2011-09-01

    In this study, ZnO nanoparticles (ZNP) of approximately 30 nm in size were synthesized by the hydrothermal method and characterized by X-ray diffraction (XRD), Braun-Emmet-Teller (BET) N2 adsorption analysis and transmission electron microscopy (TEM). ZnO nanoparticles enriched with poly(vinylferrocenium) (PVF+) modified single-use graphite electrodes were then developed for the electrochemical monitoring of nucleic acid hybridization related to the Hepatitis B Virus (HBV). Firstly, the surfaces of polymer modified and polymer-ZnO nanoparticle modified single-use pencil graphite electrodes (PGEs) were characterized using scanning electron microscopy (SEM). The electrochemical behavior of these electrodes was also investigated using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Subsequently, the polymer-ZnO nanoparticle modified PGEs were evaluated for the electrochemical detection of DNA based on the changes at the guanine oxidation signals. Various modifications in DNA oligonucleotides and probe concentrations were examined in order to optimize the electrochemical signals that were generated by means of nucleic acid hybridization. After the optimization studies, the sequence-selective DNA hybridization was investigated in the case of a complementary amino linked probe (target), or noncomplementary (NC) sequences, or target and mismatch (MM) mixture in the ratio of (1:1). Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Investigation of the cleanliness of transferred graphene. The first step toward its application as a window material for electron microscopy and spectroscopy

    International Nuclear Information System (INIS)

    Ma, Tao; Miyazaki, Kotaro; Ariga, Hiroko; Takakusagi, Satoru; Asakura, Kiyotaka

    2015-01-01

    The cleanliness of transferred graphene is of significant importance for its application as the window material in environmental cells used for electron microscopy and spectroscopy. We investigated the dependence of the cleanliness of graphene on transfer routes, including FeCl 3 etching, (NH 4 ) 2 S 2 O 8 etching, electrochemical delamination, and O 2 -bubbling, by means of transmission electron microscopy and X-ray photoelectron spectroscopy. It was found that electrochemical delamination provided the cleanest graphene with only a small amount of poly(methyl methacrylate) (PMMA) residue existing on the surface. (author)

  16. Effects of solution viscosity on heterogeneous electron transfer across a liquid/liquid interface

    Energy Technology Data Exchange (ETDEWEB)

    Bai Yamin; Sun Peng; Zhang Meiqin; Gao Zhao; Yang Zhengyu; Shao Yuanhua

    2003-10-15

    Scanning electrochemical microscopy (SECM) is employed to investigate the effect of solution viscosity on the rate constants of electron transfer (ET) reaction between potassium ferricyanide in water and 7,7,8,8-tetracyanoquinodimethane (TCNQ) in 1,2-dichloroethane. Either tetrabutylammonium (TBA{sup +}) or ClO{sub 4}{sup -} is chosen as the common ion in both phases to control the interfacial potential drop. The rate constant of heterogeneous ET reaction between TCNQ and ferrocyanide produced in-situ, k{sub 12}, is evaluated by SECM and is inversely proportional to the viscosity of the aqueous solution and directly proportional to the diffusion coefficient of K{sub 4}Fe(CN){sub 6} in water when the concentration of TCNQ in the DCE phase is in excess. The k{sub 12} dependence on viscosity is explained in terms of the longitudinal relaxation time of the solution. The rate constant of the heterogeneous ET reaction between TCNQ{sup -} and ferricyanide, k{sub 21}, is also obtained by SECM and these results cannot be explained by the same manner.

  17. Photoinducedly electrochemical preparation of Prussian blue film and electrochemical modification of the film with cetyltrimethylammonium cation

    Energy Technology Data Exchange (ETDEWEB)

    Liu Shouqing, E-mail: shouqing_liu@hotmail.co [Key Laboratory of Environmental Functional Materials of Jiangsu Province, College of Chemistry and Bioengineering, Suzhou University of Science and Technology, Suzhou 215009 (China); Li Hua; Sun Weihui; Wang Xiaomei; Chen Zhigang [Key Laboratory of Environmental Functional Materials of Jiangsu Province, College of Chemistry and Bioengineering, Suzhou University of Science and Technology, Suzhou 215009 (China); Xu Jingjuan; Ju Huangxian; Chen Hongyuan [Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education, Nanjing University, Nanjing 210093 (China)

    2011-04-15

    Research highlights: {yields} Cetyltrimethylammonium cations work as counter ions in Prussian blue film was observed and confirmed by cyclic voltammetry, Fourier transform infrared spectroscopy, X-ray powder diffraction measurements, scanning electronic microscopy and transmission electron microscope for the first time. {yields} Because the cetyltrimethylammonium cations in Prussian blue film are hydrophobic, the Prussian blue film is very stable even in alkali solution, which provides a technical basis for fabrication of stable biosensors. - Abstract: This work presents a photoinducedly electrochemical preparation of Prussian blue from a single sodium nitroprusside and insertion of cetyltrimethylammonium cations into Prussian blue as counter ions. The product of photoinducedly electrochemical reactions has a couple of voltammetric peaks at E{sup o} = 0.266 V in 0.2 mol l{sup -1} KCl solution, the measurements of X-ray powder diffraction and FT-IR spectroscopy show that it is Prussian blue (PB). The formation mechanism of a pre-photochemical reaction and subsequent electrochemical reaction is suggested. The cyclic voltammetric treatment of the freshly as-prepared PB film in 1.0 mmol l{sup -1} cetyltrimethylammonium (CTA) bromide solution leads to the insertion of cetyltrimethylammonium cations into the channels of Prussian blue, which substitutes for potassium ions as counter ions in Prussian blue. The Prussian blue containing CTA counter ions shows two couples of voltammetric peaks at E{sup o} = -0.106 V and E{sup o} = 0.249 V in 0.2 mol l{sup -1} KCl solution containing 1.0 mmol l{sup -1} cetyltrimethylammonium bromide. Compared with the electrochemical behaviors of KFeFe(CN){sub 6} in 0.1 mol l{sup -1} KOH alkali solution, CTAFeFe(CN){sub 6} shows relatively durable voltammetric currents due to the hydrophobic effects of cetyltrimethylammonium. The diffusion coefficients for CTA and potassium cations were estimated to be D{sub CTA} 1.25 x 10{sup -12} cm{sup 2} s

  18. Electrochemical Promotion of Catalytic Reactions Using

    DEFF Research Database (Denmark)

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

    2007-01-01

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

  19. Three dimensional electrochemical system for neurobiological studies

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  20. The Strategic Electrochemical Research Center in Denmark

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Hansen, Karin Vels

    2011-01-01

    A 6-year strategic electrochemistry research center (SERC) in fundamental and applied aspects of electrochemical cells with a main emphasis on solid oxide cells was started in Denmark on January 1st, 2007 in cooperation with other Danish and Swedish Universities. Furthermore, 8 Danish companies...... are presented. ©2011 COPYRIGHT ECS - The Electrochemical Society...

  1. Electrochemical synthesis of nanosized hydroxyapatite by pulsed direct current method

    Energy Technology Data Exchange (ETDEWEB)

    Nur, Adrian; Rahmawati, Alifah; Ilmi, Noor Izzati; Affandi, Samsudin; Widjaja, Arief [Departement of Chemical Engineering, Faculty of Industrial Technology, Sepuluh Nopember Institute of Technology, Kampus ITS Sukolilo, Surabaya 60111 (Indonesia)

    2014-02-24

    Synthesis of nanosized of hydroxyapatite (HA) by electrochemical pulsed direct current (PDC) method has been studied. The aim of this work is to study the influence of various PDC parameters (pH initial, electrode distance, duty cycle, frequency, and amplitude) on particle surface area of HA powders. The electrochemical synthesis was prepared in solution Ca{sup 2+}/EDTA{sup 4−}/PO{sub 4}{sup 3+} at concentration 0.25/0.25/0.15 M for 24 h. The electrochemical cell was consisted of two carbon rectangular electrodes connected to a function generator to produce PDC. There were two treatments for particles after electrosynthesized, namely without aging and aged for 2 days at 40 °C. For both cases, the particles were filtered and washed by demineralized water to eliminate the impurities and unreacted reactants. Then, the particles were dried at 100 °C for 2 days. The dried particles were characterized by X-ray diffraction, surface area analyzer, scanning electron microscopy (SEM), Fourier transform infrared spectra and thermogravimetric and differential thermal analysis. HA particles can be produced when the initial pH > 6. The aging process has significant effect on the produced HA particles. SEM images of HA particles showed that the powders consisted of agglomerates composed of fine crystallites and have morphology plate-like and sphere. The surface area of HA particles is in the range of 25 – 91 m{sup 2}/g. The largest particle surface area of HA was produced at 4 cm electrode distance, 80% cycle duty, frequency 0.1 Hz, amplitude 9 V and with aging process.

  2. Asymmetric electrochemical supercapacitor, based on polypyrrole coated carbon nanotube electrodes

    International Nuclear Information System (INIS)

    Su, Y.; Zhitomirsky, I.

    2015-01-01

    Highlights: • Polypyrrole (PPy) coated multiwalled carbon nanotubes (MWCNT) were prepared. • New method is based on the use of new electrochemically active dopants for PPy. • The dopans provided dispersion of MWCNT and promoted PPy coating formation. • Symmetric PPy–MWCNT supercapacitors showed high capacitance and low resistance. • Asymmetric PPy–MWCNT/VN–MWCNT devices and modules allowed larger voltage window. - Abstract: Conductive polypyrrole (PPy) polymer – multiwalled carbon nanotubes (MWCNT) composites were synthesized using sulfanilic acid azochromotrop (SPADNS) and sulfonazo III sodium salt (CHR-BS) as anionic dopants for chemical polymerization of PPy. The composites were tested for application in electrodes of electrochemical supercapacitors (ES). Sedimentation tests, electrophoretic deposition experiments and Fourier transform infrared spectroscopy (FTIR) investigations showed that strong adsorption of anionic CHR-BS on MWCNT provided MWCNT dispersion. The analysis of scanning and transmission electron microscopy data demonstrated that the use of CHR-BS allowed the formation of PPy coatings on MWCNT. As a result, the composites, prepared using CHR-BS, showed higher capacitance, compared to the composites, prepared using SPADNS. The electrodes, containing MWCNT, coated with PPy showed a capacitance of 179 F g −1 for active mass loading of 10 mg cm −2 , good capacitance retention at scan rates in the range of 2–100 mV s −1 and excellent cyclic stability. Asymmetric ES devices, containing positive PPy–MWCNT electrodes and negative vanadium nitride (VN)–MWCNT electrodes showed significant improvement in energy storage performance, compared to the symmetric ES due to the larger voltage window. The low impedance and high capacitance of the individual cells paved the way to the development of modules with higher voltage, which showed good electrochemical performance

  3. Electrochemical Reduction Process for Pyroprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Eun-Young; Hong, Sun-Seok; Park, Wooshin; Im, Hun Suk; Oh, Seung-Chul; Won, Chan Yeon; Cha, Ju-Sun; Hur, Jin-Mok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-06-15

    Nuclear energy is expected to meet the growing energy demand while avoiding CO{sub 2} emission. However, the problem of accumulating spent fuel from current nuclear power plants which is mainly composed of uranium oxides should be addressed. One of the most practical solutions is to reduce the spent oxide fuel and recycle it. Next-generation fuel cycles demand innovative features such as a reduction of the environmental load, improved safety, efficient recycling of resources, and feasible economics. Pyroprocessing based on molten salt electrolysis is one of the key technologies for reducing the amount of spent nuclear fuel and destroying toxic waste products, such as the long-life fission products. The oxide reduction process based on the electrochemical reduction in a LiCl-Li{sub 2}O electrolyte has been developed for the volume reduction of PWR (Pressurized Water Reactor) spent fuels and for providing metal feeds for the electrorefining process. To speed up the electrochemical reduction process, the influences of the feed form for the cathode and the type of anode shroud on the reduction rate were investigated.

  4. Electrochemical treatment of liquid wastes

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.T. [Savannah River Technology Center, Aiken, SC (United States)

    1997-10-01

    Under this task, electrochemical treatment processes are being evaluated and developed for the destruction of organic compounds and nitrates/nitrites and the removal of other hazardous species from liquid wastes stored throughout the DOE complex. This technology targets the (1) destruction of nitrates, nitrites and organic compounds; (2) removal of radionuclides; and (3) removal of RCRA metals. The development program consists of five major tasks: (1) evaluation of electrochemical reactors for the destruction and removal of hazardous waste components, (2) development and validation of engineering process models, (3) radioactive laboratory-scale tests, (4) demonstration of the technology in an engineering-scale reactor, and (5) analysis and evaluation of test data. The development program team is comprised of individuals from national laboratories, academic institutions, and private industry. Possible benefits of this technology include: (1) improved radionuclide separation as a result of the removal of organic complexants, (2) reduction in the concentrations of hazardous and radioactive species in the waste (e.g., removal of nitrate, mercury, chromium, cadmium, {sup 99}Tc, and {sup 106}Ru), (3) reduction in the size of the off-gas handling equipment for the vitrification of low-level waste (LLW) by reducing the source of NO{sub x} emissions, (4) recovery of chemicals of value (e.g. sodium hydroxide), and (5) reduction in the volume of waste requiring disposal.

  5. Electrochemical Reduction of Zinc Phosphate

    International Nuclear Information System (INIS)

    Kim, Chang Hwan; Lee, Jung Hyun; Shin, Woon Sup

    2010-01-01

    We demonstrated first that the electrochemical reduction of zinc phosphate in neutral phosphate buffer is possible and potentially applicable to bio-compatible rechargeable battery. The actual redox component is Zn(s)/Zn phosphate(s) and the future research about the control of crystal formation for the better cyclability is required. In lead-acid battery, the electrochemical redox reaction of Pb (s) /PbSO 4(s) is used by reducing Pb(II) and oxidizing Pb(0) in sulfate rich solution. Since both reduced form and oxidized form are insoluble, they cannot diffuse to the opposite electrodes and react. It is a very common strategy to make a stable battery electrode that a metal element is reduced and oxidized in solution containing an abundance of anion readily precipitating with the metal ion. For the application of this strategy to construction of rechargeable battery using bio-compatible electrode materials and electrolytes, the use of phosphate ion can be considered as anion readily precipitating with metal ions. If phosphate buffer with neutral pH is used as electrolyte, the better bio-compatibility will be achieved than most of rechargeable battery using strong acid, strong base or organic solvent as electrolyte solution. There are many metal ions readily precipitating with phos-phate ion, and zinc is one of them

  6. Solid oxide electrochemical reactor science.

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Neal P. (Colorado School of Mines, Golden, CO); Stechel, Ellen Beth; Moyer, Connor J. (Colorado School of Mines, Golden, CO); Ambrosini, Andrea; Key, Robert J. (Colorado School of Mines, Golden, CO)

    2010-09-01

    Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid oxide electrolyzer cells (SOEC), which are the reverse of solid-oxide fuel cells (SOFC). SOECs complement Sandia's efforts in thermochemical production of alternative fuels. An SOEC technology would co-electrolyze carbon dioxide (CO{sub 2}) with steam at temperatures around 800 C to form synthesis gas (H{sub 2} and CO), which forms the building blocks for a petrochemical substitutes that can be used to power vehicles or in distributed energy platforms. The effort described here concentrates on research concerning catalytic chemistry, charge-transfer chemistry, and optimal cell-architecture. technical scope included computational modeling, materials development, and experimental evaluation. The project engaged the Colorado Fuel Cell Center at CSM through the support of a graduate student (Connor Moyer) at CSM and his advisors (Profs. Robert Kee and Neal Sullivan) in collaboration with Sandia.

  7. Nanodevices in nature: Electrochemical aspects

    International Nuclear Information System (INIS)

    Volkov, Alexander G.; Volkova-Gugeshashvili, Maya I.; Brown-McGauley, Courtney L.; Osei, Albert J.

    2007-01-01

    Electrochemical multielectron reactions in photosynthesis and respiration are evaluated by thermodynamic and kinetic analysis. Kharkats and Volkov [Yu.I. Kharkats, A.G. Volkov, Biochim. Biophys. Acta 891 (1987) 56] were the first to present proof that cytochrome c oxidase reduces molecular oxygen by synchronous multielectron mechanism without O 2 - intermediate formation. After this pioneering observation, it became clear that the first step of oxygen reduction is two-electron concerted process. The energy for the H + -pump of cytochrome oxidase is liberated when the third and fourth electrons are added in the last two steps of water formation independent of the reaction pathway. Electrochemical principles govern many biological properties of organisms, such as the generation of electric fields, and the conduction of fast excitation waves. These properties are supported by the function of a variety of natural nanodevices. Ionic channels, as natural nanodevices, control the plasma membrane potential, and the movement of ions across membranes; thereby, regulating various biological functions. Some voltage-gated ion channels work as plasma membrane nanopotentiostats. In plants, excitation waves are possible mechanisms for intercellular and intracellular communication in response to environmental changes. The role of electrified nanointerface of the plasma membrane in signal transduction is discussed as well

  8. Buffered Electrochemical Polishing of Niobium

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Tian, Hui [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); College of William and Mary, Williamsburg, VA (United States); Corcoran, Sean [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2011-03-01

    The standard preparation of superconducting radio-frequency (SRF) cavities made of pure niobium include the removal of a 'damaged' surface layer, by buffered chemical polishing (BCP) or electropolishing (EP), after the cavities are formed. The performance of the cavities is characterized by a sharp degradation of the quality factor when the surface magnetic field exceeds about 90 mT, a phenomenon referred to as 'Q-drop.' In cavities made of polycrystalline fine grain (ASTM 5) niobium, the Q-drop can be significantly reduced by a low-temperature (? 120 °C) 'in-situ' baking of the cavity if the chemical treatment was EP rather than BCP. As part of the effort to understand this phenomenon, we investigated the effect of introducing a polarization potential during buffered chemical polishing, creating a process which is between the standard BCP and EP. While preliminary results on the application of this process to Nb cavities have been previously reported, in this contribution we focus on the characterization of this novel electrochemical process by measuring polarization curves, etching rates, surface finish, electrochemical impedance and the effects of temperature and electrolyte composition. In particular, it is shown that the anodic potential of Nb during BCP reduces the etching rate and improves the surface finish.

  9. Bussing Structure In An Electrochemical Cell

    Science.gov (United States)

    Romero, Antonio L.

    2001-06-12

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

  10. Light microscopy - Methods and protocols

    Directory of Open Access Journals (Sweden)

    CarloAlberto Redi

    2011-11-01

    Full Text Available The first part of the book (six chapters is devoted to some selected applications of bright-field microscopy while the second part (eight chapters to some fluorescence microscopy studies. Both animal and plant biology investigations are presented covering multiple fields like immunology, cell signaling, cancer biology and, surprisingly to me, ecology. This chapter is titled: Light microscopy in aquatic ecology: Methods for plankton communities studies and it is due to Maria Carolina S. Soares and colleagues from the Laboratory of Aquatic Ecology, Dept. of Biology, Federal University of Juiz de Fora (Brazil. Here they present methods to quantify the different component of planktonic communities in a step-by-step manner so that virus, bacteria, algae and animals pertaining to different taxa can be recognized and the contribution they made to the plankton composition evaluated. It descends that even how the plankton composition is changing due to environmental variations can be accurately determined....

  11. Optically Designed Anodised Aluminium Surfaces: Microstructural and Electrochemical Aspects

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy

    is not possible as the anodic pore sizes are an order of magnitude smaller than the traditional white pigments. The approaches presented in this thesis focus on different techniques like modification of the aluminium microstructure, engineering of the aluminium surface, and application on non...... the microstructure in order to impart light scattering ability to the anodised layer. Coatings based on Al-Zr and Al-Ti binary system were studied for their anodising behaviour with and without heat treatment. The structure evolution of the Al-Zr sputtered coatings and the effect of Si during heat treatment...... Emission Spectroscopy, and Scanning Kelvin Probe Force Microscopy. Optical characterization was performed using integrating sphere measurements. Combining the results and understanding obtained from anodising of magnetron sputtered coatings, Al-TiO2 surface composites and their electrochemical behaviour...

  12. Corrosion mitigation of J55 steel in 3.5% NaCl solution by a macrocyclic inhibitor

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ambrish [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University), Chengdu, Sichuan 610500 (China); Department of Chemistry, LFTS, Lovely Professional University, Phagwara, Punjab 144402 (India); Lin, Yuanhua, E-mail: yhlin28@163.com [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University), Chengdu, Sichuan 610500 (China); Obot, I.B. [Centre of Research Excellence in Corrosion, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Ebenso, Eno E. [Department of Chemistry, School of Mathematical & Physical Sciences, North-West University (Mafikeng Campus), Private Bag X2046, Mmabatho 2735 (South Africa); Material Science Innovation & Modelling (MaSIM) Focus Area, Faculty of Agriculture, Science and Technology, North-West University (Mafikeng Campus), Private Bag X2046, Mmabatho 2735 (South Africa); Ansari, K.R.; Quraishi, M.A. [Department of Applied Chemistry, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005, Uttar Pradesh (India)

    2015-11-30

    Graphical abstract: SECM studies revealed decrease of steady current in the presence of inhibitor while it increased for 3.5% NaCl solution that acted as the conductor. - Highlights: • J55 steel protection in 3.5% NaCl solution saturated with CO{sub 2} by HPT. • Potentiodynamic polarization curves reveal that the actions of HPT are mixed type. • The adsorption of HPT obeys the Langmuir adsorption isotherm. • Scanning electrochemical microscopy is used to discuss the insulated and conductive surface. - Abstract: 1,2,4,7,9,10-Hexaazacyclo-pentadeca-10,15-dien-3,5,6,8-tetraone (HPT) a macrocyclic compound has been studied using electrochemical methods and scanning electrochemical microscopy (SECM) techniques. The R{sub ct} values increased and C{sub dl} values decreased with the increase in concentration of the inhibitor. The corrosion inhibition of J55 steel in 3.5 wt.% NaCl solution saturated with CO{sub 2} by polarization studies revealed that HPT acted as a mixed type inhibitor. The adsorption of HPT on the J55 steel surface obeyed the Langmuir adsorption isotherm. The thermodynamic parameters (K{sub ads}, ΔG°{sub ads}) were also computed and discussed.

  13. Corrosion mitigation of J55 steel in 3.5% NaCl solution by a macrocyclic inhibitor

    International Nuclear Information System (INIS)

    Singh, Ambrish; Lin, Yuanhua; Obot, I.B.; Ebenso, Eno E.; Ansari, K.R.; Quraishi, M.A.

    2015-01-01

    Graphical abstract: SECM studies revealed decrease of steady current in the presence of inhibitor while it increased for 3.5% NaCl solution that acted as the conductor. - Highlights: • J55 steel protection in 3.5% NaCl solution saturated with CO 2 by HPT. • Potentiodynamic polarization curves reveal that the actions of HPT are mixed type. • The adsorption of HPT obeys the Langmuir adsorption isotherm. • Scanning electrochemical microscopy is used to discuss the insulated and conductive surface. - Abstract: 1,2,4,7,9,10-Hexaazacyclo-pentadeca-10,15-dien-3,5,6,8-tetraone (HPT) a macrocyclic compound has been studied using electrochemical methods and scanning electrochemical microscopy (SECM) techniques. The R ct values increased and C dl values decreased with the increase in concentration of the inhibitor. The corrosion inhibition of J55 steel in 3.5 wt.% NaCl solution saturated with CO 2 by polarization studies revealed that HPT acted as a mixed type inhibitor. The adsorption of HPT on the J55 steel surface obeyed the Langmuir adsorption isotherm. The thermodynamic parameters (K ads , ΔG° ads ) were also computed and discussed.

  14. Platinum nanoparticles functionalized nitrogen doped graphene platform for sensitive electrochemical glucose biosensing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhanjun, E-mail: zjyang@yzu.edu.cn; Cao, Yue; Li, Juan; Jian, Zhiqin; Zhang, Yongcai; Hu, Xiaoya

    2015-04-29

    Highlights: • An efficient PtNPs@NG nanocomposite was prepared for the immobilization of enzyme. • A novel electrochemical glucose biosensor was constructed based on this PtNPs@NG. • The proposed glucose biosensor showed high sensitivity and low detection limit. • The PtNPs@NG composite provided a promising platform for biosensing applications. - Abstract: In this work, we reported an efficient platinum nanoparticles functionalized nitrogen doped graphene (PtNPs@NG) nanocomposite for devising novel electrochemical glucose biosensor for the first time. The fabricated PtNPs@NG and biosensor were characterized using transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, static water contact angle, UV–vis spectroscopy, electrochemical impedance spectra and cyclic voltammetry, respectively. PtNPs@NG showed large surface area and excellent biocompatibility, and enhanced the direct electron transfer between enzyme molecules and electrode surface. The glucose oxidase (GOx) immobilized on PtNPs@NG nanocomposite retained its bioactivity, and exhibited a surface controlled, quasi-reversible and fast electron transfer process. The constructed glucose biosensor showed wide linear range from 0.005 to 1.1 mM with high sensitivity of 20.31 mA M{sup −1} cm{sup −2}. The detection limit was calculated to be 0.002 mM at signal-to-noise of 3, which showed 20-fold decrease in comparison with single NG-based electrochemical biosensor for glucose. The proposed glucose biosensor also demonstrated excellent selectivity, good reproducibility, acceptable stability, and could be successfully applied in the detection of glucose in serum samples at the applied potential of −0.33 V. This research provided a promising biosensing platform for the development of excellent electrochemical biosensors.

  15. Electrochemical behaviour and nanoscale characteristics of CNT-based fibers as new substrate for cell growth

    Energy Technology Data Exchange (ETDEWEB)

    Polizu, S.; Yahia, L.H. [Ecole Polytechnique de Montreal, PQ (Canada). Laboratoire d' innovation et d' analyse de la bioperformance; Savadogo, O. [Ecole Polytechnique de Montreal, Montreal, PQ (Canada). Laboratoire de nouveaux materiaux pour l' energie et l' electrochimie; Maugey, M.; Poulin, P. [Centre de Recherche Paul Pascal, CNRS, Bordeaux (France); Rouabhia, M. [Laval Univ., Quebec City, PQ (Canada). Faculty of Medicine

    2008-07-01

    This paper reported on a study in which carbon nanotube (CNT) macroscopic fibers were formulated by a newly developed non-covalent method for fabricating fibrous substrate. The covalent and noncovalent chemistry of CNTs has been widely used in the development of CNT-based biomaterials as active substrates for living cells. Time of Flight Mass Spectroscopy (TOF-SIMS) analysis was used to determine the surface characteristics of the CNT-based fibers produced by wet spinning method. The structure and texture of fibers were imaged using Low-Vacuum Scanning Electron Microscopy (LV-SEM) equipped with an Energy Dispersive Spectrometer (EDS) for microanalysis. Atomic Force Microscopy (AFM) imaging revealed the structure of fibers. Cyclic Voltametry (CV) measurements were performed to examine the electrochemical behaviour of fibers. Sulfuric acid and a cell culture medium was used as the 2 different electrolytes. The influences of environmental parameters on the electrochemical phenomena taking place were identified. The intrinsic electrochemical characteristics of fibers were revealed through measurements in acid environment. The cell culture medium simulated the physiological conditions. It was concluded that the newly developed wet spinning method is very efficient for making CNT-based fibers as electroactive biomaterials. The structural nanoscale details evidenced a good alignment of nanotubes in the thread and the critical role it plays in electrochemical interactions. The differences induced by the variation of electrolytes suggest that a relationship could be established between the fiber chemistry and the electrochemical response. This correlation has considerably potential for the design of new biomedical devices. 2 refs.

  16. Platinum nanoparticles functionalized nitrogen doped graphene platform for sensitive electrochemical glucose biosensing

    International Nuclear Information System (INIS)

    Yang, Zhanjun; Cao, Yue; Li, Juan; Jian, Zhiqin; Zhang, Yongcai; Hu, Xiaoya

    2015-01-01

    Highlights: • An efficient PtNPs@NG nanocomposite was prepared for the immobilization of enzyme. • A novel electrochemical glucose biosensor was constructed based on this PtNPs@NG. • The proposed glucose biosensor showed high sensitivity and low detection limit. • The PtNPs@NG composite provided a promising platform for biosensing applications. - Abstract: In this work, we reported an efficient platinum nanoparticles functionalized nitrogen doped graphene (PtNPs@NG) nanocomposite for devising novel electrochemical glucose biosensor for the first time. The fabricated PtNPs@NG and biosensor were characterized using transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, static water contact angle, UV–vis spectroscopy, electrochemical impedance spectra and cyclic voltammetry, respectively. PtNPs@NG showed large surface area and excellent biocompatibility, and enhanced the direct electron transfer between enzyme molecules and electrode surface. The glucose oxidase (GOx) immobilized on PtNPs@NG nanocomposite retained its bioactivity, and exhibited a surface controlled, quasi-reversible and fast electron transfer process. The constructed glucose biosensor showed wide linear range from 0.005 to 1.1 mM with high sensitivity of 20.31 mA M −1 cm −2 . The detection limit was calculated to be 0.002 mM at signal-to-noise of 3, which showed 20-fold decrease in comparison with single NG-based electrochemical biosensor for glucose. The proposed glucose biosensor also demonstrated excellent selectivity, good reproducibility, acceptable stability, and could be successfully applied in the detection of glucose in serum samples at the applied potential of −0.33 V. This research provided a promising biosensing platform for the development of excellent electrochemical biosensors

  17. Fabrication of highly sensitive gold nanourchins based electrochemical sensor for nanomolar determination of primaquine

    Energy Technology Data Exchange (ETDEWEB)

    Thapliyal, Neeta Bachheti, E-mail: thapliyaln@ukzn.ac.za; Chiwunze, Tirivashe Elton; Karpoormath, Rajshekhar, E-mail: karpoormath@ukzn.ac.za; Cherukupalli, Srinivasulu

    2017-05-01

    A gold nanourchins modified glassy carbon electrode (AuNu/GCE) was developed for the determination of antimalarial drug, primaquine (PQ). The surface of AuNu/GCE was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and cyclic voltammetry (CV). EIS results indicated that the electron transfer process at AuNu/GCE was faster as compared to the bare electrode. The SEM and TEM image confirmed the presence and uniform dispersion of gold nanourchins on the GCE surface. Upon investigating the electrochemical behavior of PQ at AuNu/GCE, the developed sensor was found to exhibit high electrocatalytic activity towards the oxidation of PQ. Under optimal experimental conditions, the sensor showed fast and sensitive current response to PQ over a linear concentration range of 0.01–1 μM and 0.001–1 μM with a detection limit of 3.5 nM and 0.9 nM using differential pulse voltammetry (DPV) and square wave voltammetry (SWV), respectively. The AuNu/GCE showed good selectivity, reproducibility and stability. Further, the developed sensor was successfully applied to determine the drug in human urine samples and pharmaceutical formulations demonstrating its analytical applicability in clinical analysis as well as quality control. The proposed method thus provides a promising alternative in routine sensing of PQ as well as promotes the application of gold nanourchins in electrochemical sensors. - Graphical abstract: A gold nanourchins modified glassy carbon electrode was fabricated and used as an electrochemical sensing platform for the determination of primaquine. Display Omitted - Highlights: • Gold nanourchins based electrochemical sensor for determination of primaquine • A detection limit of 0.9 nM was obtained using square wave voltammetry. • Proposed method was applied to quantify the drug in tablet and human urine samples. • Fast, simple and low-cost method for trace analysis of

  18. Fabrication of highly sensitive gold nanourchins based electrochemical sensor for nanomolar determination of primaquine

    International Nuclear Information System (INIS)

    Thapliyal, Neeta Bachheti; Chiwunze, Tirivashe Elton; Karpoormath, Rajshekhar; Cherukupalli, Srinivasulu

    2017-01-01

    A gold nanourchins modified glassy carbon electrode (AuNu/GCE) was developed for the determination of antimalarial drug, primaquine (PQ). The surface of AuNu/GCE was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and cyclic voltammetry (CV). EIS results indicated that the electron transfer process at AuNu/GCE was faster as compared to the bare electrode. The SEM and TEM image confirmed the presence and uniform dispersion of gold nanourchins on the GCE surface. Upon investigating the electrochemical behavior of PQ at AuNu/GCE, the developed sensor was found to exhibit high electrocatalytic activity towards the oxidation of PQ. Under optimal experimental conditions, the sensor showed fast and sensitive current response to PQ over a linear concentration range of 0.01–1 μM and 0.001–1 μM with a detection limit of 3.5 nM and 0.9 nM using differential pulse voltammetry (DPV) and square wave voltammetry (SWV), respectively. The AuNu/GCE showed good selectivity, reproducibility and stability. Further, the developed sensor was successfully applied to determine the drug in human urine samples and pharmaceutical formulations demonstrating its analytical applicability in clinical analysis as well as quality control. The proposed method thus provides a promising alternative in routine sensing of PQ as well as promotes the application of gold nanourchins in electrochemical sensors. - Graphical abstract: A gold nanourchins modified glassy carbon electrode was fabricated and used as an electrochemical sensing platform for the determination of primaquine. Display Omitted - Highlights: • Gold nanourchins based electrochemical sensor for determination of primaquine • A detection limit of 0.9 nM was obtained using square wave voltammetry. • Proposed method was applied to quantify the drug in tablet and human urine samples. • Fast, simple and low-cost method for trace analysis of

  19. Effect of graphene oxide nanoplatelets on electrochemical properties of steel substrate in saline media

    International Nuclear Information System (INIS)

    Chaudhry, A.U.; Mittal, Vikas; Mishra, Brajendra

    2015-01-01

    There has been increased interest in using graphene oxide (GO) in various industrial applications such as working fluids, lubricants, oil and gas fields, heavy metal removal from water, anticorrosion paints and coatings etc. We studied electrochemical properties of steel in the presence of suspended GO in saline media. GO suspension has been characterized using Transmission electron microscopy (TEM) and X-ray diffractometer (XRD). We measured the effect of the GO concentration (0–15 ppm) on electrochemical properties of steel using different techniques: open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and potentiodynamic (PD) methods. Results indicate that the suppression of corrosion is directly proportional to increasing GO concentrations in saline environments. Surface morphology of corroded samples was examined using Scanning Electron Microscopy (SEM). Identification of the elements at accumulated layer was estimated from peaks of energy dispersive x-ray spectroscopy (EDX) and XRD. Increased protection abilities with increasing GO concentration have been attributed to the domination of salt layer presence at the surface of steel which occurs via precipitation of sodium chloride. Surface analysis confirm that there is no direct effect of GO on the protection behavior of steel. The presence of GO in the solution can enhance the precipitation of NaCl due to the decreased solubility NaCl which further slows down the corrosion. The pourbaix diagram shows that GO forms an anionic compound with sodium which may enhance the precipitation at working electrode. - Graphical abstract: Display Omitted - Highlights: • Electrochemical properties of steel in saline media containing nano graphene oxide. • Effect of concentration of graphene oxide on electrochemical properties. • Mechanism of corrosion reduction due to the presence of graphene oxide

  20. GOX-functionalized nanodiamond films for electrochemical biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Villalba, Pedro [Department of Chemical and Biomedical Engineering, University of South Florida (United States); Departamento de Medicina, Universidad del Norte, Barranquilla (Colombia); Ram, Manoj K., E-mail: mkram@usf.edu [Department of Mechanical Engineering, University of South Florida, 4202 E Fowler Avenue, Tampa, FL, 33620-5350 (United States); Nanotechnology Research and Education Center, University of South Florida (United States); Gomez, Humberto [Department of Mechanical Engineering, University of South Florida, 4202 E Fowler Avenue, Tampa, FL, 33620-5350 (United States); Departamento de Medicina, Universidad del Norte, Barranquilla (Colombia); Kumar, Amrita [Department of Physiology, Emory University. Atlanta GA (United States); Bhethanabotla, Venkat [Department of Chemical and Biomedical Engineering, University of South Florida (United States); Kumar, Ashok [Department of Mechanical Engineering, University of South Florida, 4202 E Fowler Avenue, Tampa, FL, 33620-5350 (United States); Nanotechnology Research and Education Center, University of South Florida (United States)

    2011-07-20

    The importance of nanodiamond in biological and technological applications has been recognized recently, and applied in drug delivery, biochip, sensors and biosensors. Under this investigation, nanodiamond (ND) and nitrogen doped nanodiamond (NND) were deposited on n-type silicon films, and later functionalized with enzyme Glucose oxidase (GOX). The GOX functionalized doped and undoped ND films were characterized using combination of several techniques; i.e. FTIR spectroscopy, Raman spectroscopy, atomic force microscopy (AFM) and electrochemical techniques. ND/GOX and NND/GOX thin films on n-type silicon have been found to provide sensitive glucose sensor. GOX has been chosen as a model enzyme system to functionalize with ND at molecular level to understand the glucose biosensor. - Research highlights: {yields} Nanodiamond (ND) films were used as an enzyme electrode for glucose quantification. {yields} Electrochemical behavior of doped and intrinsic films was analyzed. {yields} Electrode demonstrates sensitivity to glucose concentration in dynamic condition. {yields} Linear behavior was observed upto 8mM before saturation condition.

  1. Electrochemical Grafting of Graphene Nano Platelets with Aryl Diazonium Salts.

    Science.gov (United States)

    Qiu, Zhipeng; Yu, Jun; Yan, Peng; Wang, Zhijie; Wan, Qijin; Yang, Nianjun

    2016-10-26

    To vary interfacial properties, electrochemical grafting of graphene nano platelets (GNP) with 3,5-dichlorophenyl diazonium tetrafluoroborate (aryl-Cl) and 4-nitrobenzene diazonium tetrafluoroborate (aryl-NO 2 ) was realized in a potentiodynamic mode. The covalently bonded aryl layers on GNP were characterized using atomic force microscopy and X-ray photoelectron spectroscopy. Electrochemical conversion of aryl-NO 2 into aryl-NH 2 was conducted. The voltammetric and impedance behavior of negatively and positively charged redox probes (Fe(CN) 6 3-/4- and Ru(NH 3 ) 6 2+/3+ ) on three kinds of aryl layers grafted on GNP reveal that their interfacial properties are determined by the charge states of redox probes and reactive terminal groups (-Cl, -NO 2 , -NH 2 ) in aryl layers. On aryl-Cl and aryl-NH 2 garted GNP, selective and sensitive monitoring of positively charged lead ions as well as negatively charged nitrite and sulfite ions was achieved, respectively. Such a grafting procedure is thus a perfect way to design and control interfacial properties of graphene.

  2. GOX-functionalized nanodiamond films for electrochemical biosensor

    International Nuclear Information System (INIS)

    Villalba, Pedro; Ram, Manoj K.; Gomez, Humberto; Kumar, Amrita; Bhethanabotla, Venkat; Kumar, Ashok

    2011-01-01

    The importance of nanodiamond in biological and technological applications has been recognized recently, and applied in drug delivery, biochip, sensors and biosensors. Under this investigation, nanodiamond (ND) and nitrogen doped nanodiamond (NND) were deposited on n-type silicon films, and later functionalized with enzyme Glucose oxidase (GOX). The GOX functionalized doped and undoped ND films were characterized using combination of several techniques; i.e. FTIR spectroscopy, Raman spectroscopy, atomic force microscopy (AFM) and electrochemical techniques. ND/GOX and NND/GOX thin films on n-type silicon have been found to provide sensitive glucose sensor. GOX has been chosen as a model enzyme system to functionalize with ND at molecular level to understand the glucose biosensor. - Research highlights: → Nanodiamond (ND) films were used as an enzyme electrode for glucose quantification. → Electrochemical behavior of doped and intrinsic films was analyzed. → Electrode demonstrates sensitivity to glucose concentration in dynamic condition. → Linear behavior was observed upto 8mM before saturation condition.

  3. High performance lithium insertion negative electrode materials for electrochemical devices

    Energy Technology Data Exchange (ETDEWEB)

    Channu, V.S. Reddy, E-mail: chinares02@gmail.com [SMC Corporation, College Station, TX 77845 (United States); Rambabu, B. [Solid State Ionics and Surface Sciences Lab, Department of Physics, Southern University and A& M College, Baton Rouge, LA 70813 (United States); Kumari, Kusum [Department of Physics, National Institute of Technology, Warangal (India); Kalluru, Rajmohan R. [The University of Southern Mississippi, College of Science and Technology, 730 E Beach Blvd, Long Beach, MS 39560 (United States); Holze, Rudolf [Institut für Chemie, AG Elektrochemie, Technische Universität Chemnitz, D-09107 Chemnitz (Germany)

    2016-11-30

    Highlights: • LiCrTiO{sub 4} nanostructures were synthesized for electrochemical applications by soft chemical synthesis followed by annealing. • The presence of Cr and Ti elements are confirmed from the EDS spectrum. • Oxalic acid assisted LiCrTiO{sub 4} electrode shows higher specific capacity (mAh/g). - Abstract: Spinel LiCrTiO{sub 4} oxides to be used as electrode materials for a lithium ion battery and an asymmetric supercapacitor were synthesized using a soft-chemical method with and without chelating agents followed by calcination at 700 °C for 10 h. Structural and morphological properties were studied with powder X-ray diffraction, scanning electron and transmission electron microscopy. Particles of 50–10 nm in size are observed in the microscopic images. The presence of Cr and Ti is confirmed from the EDS spectrum. Electrochemical properties of LiCrTiO{sub 4} electrode were examined in a lithium ion battery. The electrode prepared with oxalic acid-assisted LiCrTiO{sub 4} shows higher specific capacity.This LiCrTiO{sub 4} is also used as anode material for an asymmetric hybrid supercapacitor. The cell exhibits a specific capacity of 65 mAh/g at 1 mA/cm{sup 2}. The specific capacity decreases with increasing current densities.

  4. Electrophoretic nanotechnology of composite electrodes for electrochemical supercapacitors.

    Science.gov (United States)

    Su, Y; Zhitomirsky, I

    2013-02-14

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

  5. Kinetics of electrochemical boriding of low carbon steel

    International Nuclear Information System (INIS)

    Kartal, G.; Eryilmaz, O.L.; Krumdick, G.; Erdemir, A.; Timur, S.

    2011-01-01

    In this study, the growth kinetics of the boride layers forming on low carbon steel substrates was investigated during electrochemical boriding which was performed at a constant current density of 200 mA/cm 2 in a borax based electrolyte at temperatures ranging from 1123 K to 1273 K for periods of 5-120 min. After boriding, the presence of both FeB and Fe 2 B phases were confirmed by the X-ray diffraction method. Cross-sectional microscopy revealed a very dense and thick morphology for both boride phases. Micro hardness testing of the borided steel samples showed a significant increase in the hardness of the borided surfaces (i.e., up to (1700 ± 200) HV), while the hardness of un-borided steel samples was approximately (200 ± 20) HV. Systematic studies over a wide range of boriding time and temperature confirmed that the rate of the boride layer formation is strongly dependent on boriding duration and has a parabolic character. The activation energy of boride layer growth for electrochemical boriding was determined as (172.75 ± 8.6) kJ/mol.

  6. Single-Atom Catalysts of Precious Metals for Electrochemical Reactions.

    Science.gov (United States)

    Kim, Jiwhan; Kim, Hee-Eun; Lee, Hyunjoo

    2018-01-10

    Single-atom catalysts (SACs), in which metal atoms are dispersed on the support without forming nanoparticles, have been used for various heterogeneous reactions and most recently for electrochemical reactions. In this Minireview, recent examples of single-atom electrocatalysts used for the oxygen reduction reaction (ORR), hydrogen oxidation reaction (HOR), hydrogen evolution reaction (HER), formic acid oxidation reaction (FAOR), and methanol oxidation reaction (MOR) are introduced. Many density functional theory (DFT) simulations have predicted that SACs may be effective for CO 2 reduction to methane or methanol production while suppressing H 2 evolution, and those cases are introduced here as well. Single atoms, mainly Pt single atoms, have been deposited on TiN or TiC nanoparticles, defective graphene nanosheets, N-doped covalent triazine frameworks, graphitic carbon nitride, S-doped zeolite-templated carbon, and Sb-doped SnO 2 surfaces. Scanning transmission electron microscopy, extended X-ray absorption fine structure measurement, and in situ infrared spectroscopy have been used to detect the single-atom structure and confirm the absence of nanoparticles. SACs have shown high mass activity, minimizing the use of precious metal, and unique selectivity distinct from nanoparticle catalysts owing to the absence of ensemble sites. Additional features that SACs should possess for effective electrochemical applications were also suggested. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Electrochemical Oxidation of Cyanide Using Platinized Ti Electrodes

    Directory of Open Access Journals (Sweden)

    Aušra VALIŪNIENĖ

    2013-12-01

    Full Text Available The cyanide-containing effluents are dangerous ecological hazards and must be treated before discharging into the environment. Anodic oxidation is one of the best ways to degrade cyanides. Pt anodes as the most efficient material for the cyanide electrochemical degradation are widely used. However, these electrodes are too expensive for industrial purposes. In this work Ti electrodes covered with nano-sized Pt particle layer were prepared and used for the anodic oxidation of cyanide ions. Surface images of Ti electrodes and Ti electrodes covered with different thickness layer of Pt were compared and characterized by the atomic force microscopy (AFM. The products formed in the solution during the CN- ions electrooxidation were examined by the Raman spectroscopy. An electrochemical Fast Fourier transformation (FFT impedance spectroscopy was used to estimate the parameters that reflect real surface roughness of Pt-modified Ti electrodes.DOI: http://dx.doi.org/10.5755/j01.ms.19.4.2514

  8. Multilevel electrochemical signal detections of metalloprotein heterolayers for bioelectronic device

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Yong-Ho; Yoo, Si-Youl; Lee, Taek [Department of Chemical and Biomolecular Engineering, Sogang University, 35 Baekbeom-ro(Sinsu-dong), Mapo-gu, Seoul 121-742 (Korea, Republic of); Lee, Hun Joo [Interdisciplinary Program of Integrated Biotechnology, Sogang University, 35 Baekbeomro(Sinsu-dong), Mapo-gu, Seoul 121-742 (Korea, Republic of); Min, Junhong [School of Integrative Engineering, Chung-Ang University, Heukseok-dong, Dongjak-gu, Seoul 156-756 (Korea, Republic of); Choi, Jeong-Woo, E-mail: jwchoi@sogang.ac.kr [Department of Chemical and Biomolecular Engineering, Sogang University, 35 Baekbeom-ro(Sinsu-dong), Mapo-gu, Seoul 121-742 (Korea, Republic of); Interdisciplinary Program of Integrated Biotechnology, Sogang University, 35 Baekbeomro(Sinsu-dong), Mapo-gu, Seoul 121-742 (Korea, Republic of)

    2014-01-31

    In the present study, we investigated the simultaneous detection of multilevel electrochemical signals from various metalloprotein heterolayers for the bioelectronic devices. A layer-by-layer assembly method based on simple electrostatic interaction was introduced to form protein bilayers. The gold substrate was modified with poly (ethylene glycol) thiol acid as the precursor, which introduced negative charges to the surface. Based on the isoelectric point, net-charge controlled metalloproteins by pH adjustment were sequentially immobilized on this negatively charged substrate. The degree of protein immobilization on the gold substrate was confirmed by surface plasmon resonance spectroscopy, and the surface topology changes due to the protein immobilization were confirmed by atomic force microscopy. Redox signals in the protein layers were measured by cyclic voltammetry. As a result, various redox signals generated from different metalloproteins on a single electrode were monitored. This proposed method for the detection of multi-level electrochemical signals can be directly applied to bioelectronic devices that store multi-information in a single electrode. - Highlights: • We fabricated heterolayers composed of various metalloproteins. • Metalloproteins were immobilized by layer-by-layer assembly. • The degree of immobilization was controlled by the net charge of metalloproteins. • Various redox signals generated from heterolayers were well monitored.

  9. Structural and Electrochemical Properties of Lithium Nickel Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Gyu-bong Cho

    2014-01-01

    Full Text Available LiNiO2 thin films were fabricated by RF magnetron sputtering. The microstructure of the films was determined by X-ray diffraction and field-emission scanning electron microscopy. The electrochemical properties were investigated with a battery cycler using coin-type half-cells. The LiNiO2 thin films annealed below 500°C had the surface carbonate. The results suggest that surface carbonate interrupted the Li intercalation and deintercalation during charge/discharge. Although the annealing process enhanced the crystallization of LiNiO2, the capacity did not increase. When the annealing temperature was increased to 600°C, the FeCrNiO4 oxide phase was generated and the discharge capacity decreased due to an oxygen deficiency in the LiNiO2 thin film. The ZrO2-coated LiNiO2 thin film provided an improved discharge capacity compared to bare LiNiO2 thin film suggesting that the improved electrochemical characteristic may be attributed to the inhibition of surface carbonate by ZrO2 coating layer.

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  11. Multiphoton Microscopy for Ophthalmic Imaging

    Directory of Open Access Journals (Sweden)

    Emily A. Gibson

    2011-01-01

    Full Text Available We review multiphoton microscopy (MPM including two-photon autofluorescence (2PAF, second harmonic generation (SHG, third harmonic generation (THG, fluorescence lifetime (FLIM, and coherent anti-Stokes Raman Scattering (CARS with relevance to clinical applications in ophthalmology. The different imaging modalities are discussed highlighting the particular strength that each has for functional tissue imaging. MPM is compared with current clinical ophthalmological imaging techniques such as reflectance confocal microscopy, optical coherence tomography, and fluorescence imaging. In addition, we discuss the future prospects for MPM in disease detection and clinical monitoring of disease progression, understanding fundamental disease mechanisms, and real-time monitoring of drug delivery.

  12. Nanoscale Laser Terahertz Emission Microscopy

    DEFF Research Database (Denmark)

    Klarskov, Pernille; Kim, Hyewon; Colvin, Vicki L.

    2017-01-01

    Laser terahertz emission microscopy (LTEM) has become a powerful tool for studying ultrafast dynamics and local fields in many different types of materials. This technique, which relies on acceleration of charge carriers in a material upon femtosecond excitation, can provide insight into the phys......Laser terahertz emission microscopy (LTEM) has become a powerful tool for studying ultrafast dynamics and local fields in many different types of materials. This technique, which relies on acceleration of charge carriers in a material upon femtosecond excitation, can provide insight...

  13. Illuminating Electron Microscopy of Photocatalysts

    DEFF Research Database (Denmark)

    Cavalca, Filippo

    .1% of the surface of the planet with a device that converts solar energy into a useable form at 10% efficiency would give more than the present worldwide consumption of fossil energy. Photocatalysts are of fundamental interest for sustainable energy research because they provide a viable route for converting solar...... energy into chemical bonds. By means of Transmission Electron Microscopy (TEM) it is possible to gain insight in the fundamentals of their reaction mechanisms, chemical behaviour, structure and morphology before, during and after reaction using in situ investigations. In particular, the environmental TEM...... the microscope that allows electron microscopy under nonconventional TEM conditions and new kinds of in situ spectroscopy....

  14. Single-molecule conductance of redox molecules in electrochemical scanning tunneling microscopy

    DEFF Research Database (Denmark)

    Haiss, W.; Albrecht, Tim; van Zalinge, H.

    2007-01-01

    of a maximum in the I-tunneling versus electrode potential relationship can be fitted by a "soft" gating concept. This arises from large configurational fluctuations of the molecular bridge linked to the gold contacts by flexible chains. This view is incorporated in a formalism that is well-suited for data...... analysis and reproduces in all important respects the 6V6 data for physically sound values of the appropriate parameters. This study demonstrates that fluctuations of isolated configurationally "soft" molecules can dominate charge transport patterns and that theoretical frameworks for compact monolayers...

  15. Impedance Spectroscopic Investigation of Proton Conductivity in Nafion Using Transient Electrochemical Atomic Force Microscopy (AFM

    Directory of Open Access Journals (Sweden)

    Emil Roduner

    2012-06-01

    Full Text Available Spatially resolved impedance spectroscopy of a Nafion polyelectrolyte membrane is performed employing a conductive and Pt-coated tip of an atomic force microscope as a point-like contact and electrode. The experiment is conducted by perturbing the system by a rectangular voltage step and measuring the incurred current, followed by Fourier transformation and plotting the impedance against the frequency in a conventional Bode diagram. To test the potential and limitations of this novel method, we present a feasibility study using an identical hydrogen atmosphere at a well-defined relative humidity on both sides of the membrane. It is demonstrated that good quality impedance spectra are obtained in a frequency range of 0.2–1,000 Hz. The extracted polarization curves exhibit a maximum current which cannot be explained by typical diffusion effects. Simulation based on equivalent circuits requires a Nernst element for restricted diffusion in the membrane which suggests that this effect is based on the potential dependence of the electrolyte resistance in the high overpotential region.

  16. Electrochemical migration of tin in electronics and microstructure of the dendrites

    Energy Technology Data Exchange (ETDEWEB)

    Minzari, Daniel, E-mail: dmin@mek.dtu.d [Section for Materials and Surface Technology, Department for Mechanical Engineering, Technical University of Denmark (Denmark); Grumsen, Flemming Bjerg; Jellesen, Morten S.; Moller, Per; Ambat, Rajan [Section for Materials and Surface Technology, Department for Mechanical Engineering, Technical University of Denmark (Denmark)

    2011-05-15

    Graphical abstract: The electrochemical migration of tin in electronics forms dendritic structures, consisting of a metallic tin core, which is surrounded by oxide layers having various thickness. Display Omitted Research highlights: Electrochemical migration occurs if two conductors are connected by condensed moisture. Metallic ions are dissolved and grow in a dendritic structure that short circuit the electrodes. The dendrite consists of a metallic tin core with oxide layers of various thickness surrounding. Detailed microstructure of dendrites is investigated using electron microscopy. The dendrite microstructure is heterogeneous along the growth direction. - Abstract: The macro-, micro-, and nano-scale morphology and structure of tin dendrites, formed by electrochemical migration on a surface mount ceramic chip resistor having electrodes consisting of tin with small amounts of Pb ({approx}2 wt.%) was investigated by scanning electron microscopy and transmission electron microscopy including Energy dispersive X-ray spectroscopy and electron diffraction. The tin dendrites were formed under 5 or 12 V potential bias in 10 ppm by weight NaCl electrolyte as a micro-droplet on the resistor during electrochemical migration experiments. The dendrites formed were found to have heterogeneous microstructure along the growth direction, which is attributed to unstable growth conditions inside the micro-volume of electrolyte. Selected area electron diffraction showed that the dendrites are metallic tin having sections of single crystal orientation and lead containing intermetallic particles embedded in the structure. At certain areas, the dendrite structure was found to be surrounded by an oxide crust, which is believed to be due to unstable growth conditions during the dendrite formation. The oxide layer was found to be of nanocrystalline structure, which is expected to be formed by the dehydration of the hydrated oxide originally formed in solution ex-situ in ambient air.

  17. Force microscopy of layering and friction in an ionic liquid

    International Nuclear Information System (INIS)

    Hoth, Judith; Hausen, Florian; Bennewitz, Roland; Müser, Martin H

    2014-01-01

    The mechanical properties of the ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl) trifluorophosphate ([Py 1,4 ][FAP]) in confinement between a SiO x and a Au(1 1 1) surface are investigated by means of atomic force microscopy (AFM) under electrochemical control. Up to 12 layers of ion pairs can be detected through force measurements while approaching the tip of the AFM to the surface. The particular shape of the force versus distance curve is explained by a model for the interaction between tip, gold surface and ionic liquid, which assumes an exponentially decaying oscillatory force originating from bulk liquid density correlations. Jumps in the tip–sample distance upon approach correspond to jumps of the compliant force sensor between branches of the oscillatory force curve. Frictional force between the laterally moving tip and the surface is detected only after partial penetration of the last double layer between tip and surface. (paper)

  18. Comparison of electrochemical method with ozonation, chlorination and monochloramination in drinking water disinfection

    Energy Technology Data Exchange (ETDEWEB)

    Li Hongna, E-mail: lihongna@gmail.com [Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871 (China); Zhu Xiuping [Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871 (China); Ni Jinren, E-mail: nijinren@iee.pku.edu.cn [Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing 100871 (China)

    2011-11-30

    inactivation of the two Bacillus was much slower than E. coli and S. aureus. As a result, the non-selectivity of electrochemical disinfection with BDD anode to different kinds of microorganisms was further proved, which was primarily controlled by the hydroxyl radicals existed in the free state. For each bacterium, the order of disinfection availability of the four processes was consistent. Finally, scanning electron microscopy (SEM) was implemented to observe the cell morphology. It was shown that cell surface damage was more obvious in electrochemical system with strong oxidants compared with that after ozone treatment, while the integrity of cells were not affected in weak oxidizing chlorine and monochloramine.

  19. Comparison of electrochemical method with ozonation, chlorination and monochloramination in drinking water disinfection

    International Nuclear Information System (INIS)

    Li Hongna; Zhu Xiuping; Ni Jinren

    2011-01-01

    Bacillus was much slower than E. coli and S. aureus. As a result, the non-selectivity of electrochemical disinfection with BDD anode to different kinds of microorganisms was further proved, which was primarily controlled by the hydroxyl radicals existed in the free state. For each bacterium, the order of disinfection availability of the four processes was consistent. Finally, scanning electron microscopy (SEM) was implemented to observe the cell morphology. It was shown that cell surface damage was more obvious in electrochemical system with strong oxidants compared with that after ozone treatment, while the integrity of cells were not affected in weak oxidizing chlorine and monochloramine.

  20. High Resolution Scanning Ion Microscopy

    NARCIS (Netherlands)

    Castaldo, V.

    2011-01-01

    The structure of the thesis is the following. The first chapter is an introduction to scanning microscopy, where the path that led to the Focused Ion Beam (FIB) is described and the main differences between electrons and ion beams are highlighted. Chapter 2 is what is normally referred to (which I

  1. Illuminating Electron Microscopy of Photocatalysts

    DEFF Research Database (Denmark)

    Cavalca, Filippo

    Photocatalysts are of fundamental interest for sustainable energy research because of their wide range of applications and great potential for state of the art and future usages [1]. By means of Transmission Electron Microscopy (TEM) it is possible to give a deep insight in the structure, composi...

  2. Light Microscopy at Maximal Precision

    Directory of Open Access Journals (Sweden)

    Matthew Bierbaum

    2017-10-01

    Full Text Available Microscopy is the workhorse of the physical and life sciences, producing crisp images of everything from atoms to cells well beyond the capabilities of the human eye. However, the analysis of these images is frequently little more accurate than manual marking. Here, we revolutionize the analysis of microscopy images, extracting all the useful information theoretically contained in a complex microscope image. Using a generic, methodological approach, we extract the information by fitting experimental images with a detailed optical model of the microscope, a method we call parameter extraction from reconstructing images (PERI. As a proof of principle, we demonstrate this approach with a confocal image of colloidal spheres, improving measurements of particle positions and radii by 10–100 times over current methods and attaining the maximum possible accuracy. With this unprecedented accuracy, we measure nanometer-scale colloidal interactions in dense suspensions solely with light microscopy, a previously impossible feat. Our approach is generic and applicable to imaging methods from brightfield to electron microscopy, where we expect accuracies of 1 nm and 0.1 pm, respectively.

  3. Mechanics in Steels through Microscopy

    NARCIS (Netherlands)

    Tirumalasetty, G.K.

    2013-01-01

    The goal of the study consolidated in this thesis is to understand the mechanics in steels using microscopy. In particular, the mechanical response of Transformation Induced Plasticity (TRIP) steels is correlated with their microstructures. Chapter 1 introduces the current state of the art of TRIP

  4. Light Microscopy at Maximal Precision

    Science.gov (United States)

    Bierbaum, Matthew; Leahy, Brian D.; Alemi, Alexander A.; Cohen, Itai; Sethna, James P.

    2017-10-01

    Microscopy is the workhorse of the physical and life sciences, producing crisp images of everything from atoms to cells well beyond the capabilities of the human eye. However, the analysis of these images is frequently little more accurate than manual marking. Here, we revolutionize the analysis of microscopy images, extracting all the useful information theoretically contained in a complex microscope image. Using a generic, methodological approach, we extract the information by fitting experimental images with a detailed optical model of the microscope, a method we call parameter extraction from reconstructing images (PERI). As a proof of principle, we demonstrate this approach with a confocal image of colloidal spheres, improving measurements of particle positions and radii by 10-100 times over current methods and attaining the maximum possible accuracy. With this unprecedented accuracy, we measure nanometer-scale colloidal interactions in dense suspensions solely with light microscopy, a previously impossible feat. Our approach is generic and applicable to imaging methods from brightfield to electron microscopy, where we expect accuracies of 1 nm and 0.1 pm, respectively.

  5. Stochastic Optical Reconstruction Microscopy (STORM).

    Science.gov (United States)

    Xu, Jianquan; Ma, Hongqiang; Liu, Yang

    2017-07-05

    Super-resolution (SR) fluorescence microscopy, a class of optical microscopy techniques at a spatial resolution below the diffraction limit, has revolutionized the way we study biology, as recognized by the Nobel Prize in Chemistry in 2014. Stochastic optical reconstruction microscopy (STORM), a widely used SR technique, is based on the principle of single molecule localization. STORM routinely achieves a spatial resolution of 20 to 30 nm, a ten-fold improvement compared to conventional optical microscopy. Among all SR techniques, STORM offers a high spatial resolution with simple optical instrumentation and standard organic fluorescent dyes, but it is also prone to image artifacts and degraded image resolution due to improper sample preparation or imaging conditions. It requires careful optimization of all three aspects-sample preparation, image acquisition, and image reconstruction-to ensure a high-quality STORM image, which will be extensively discussed in this unit. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

  6. Transmission electron microscopy of bone

    NARCIS (Netherlands)

    Everts, Vincent; Niehof, Anneke; Tigchelaar-Gutter, Wikky; Beertsen, Wouter

    2012-01-01

    This chapter describes procedures to process mineralized tissues obtained from different sources for transmission electron microscopy (TEM). Methods for fixation, resin embedding, staining of semi-thin sections and ultrathin sections are presented. In addition, attention will be paid to processing

  7. Electrochemically pretreated zeolite-modified carbon-paste electrodes for determination of linuron in an agricultural formulation and water

    International Nuclear Information System (INIS)

    Siara, L.R.; Lima, F. de; Cardoso, C.A.L.; Arruda, G.J.

    2015-01-01

    Highlights: • Cyclic voltammetry, square-wave voltammetry, electrochemical impedance spectroscopic, and scanning electron microscopy were employed. • Kinetic parameters (n, α, k s , and Γ) were calculated. • High sensitivity was observed in the linear concentration range. • Excellent recovery rates were achieved for tap water samples. • The method proved applicable to the determination of linuron in the presence of potential organic and inorganic interferents, none of which affected the results. - Abstract: A simple and inexpensive, yet highly sensitive electrochemical method for quantifying linuron in tap and distilled water and in agricultural formulations was developed using electrochemically pretreated zeolite-modified carbon-paste electrodes (ZMCPEs). Compared with untreated ZMCPEs, the electrochemically pretreated electrodes showed significantly enhanced peak currents for linuron oxidation. Scanning electron microscopy and energy-dispersive x-ray spectroscopy were used to examine the structure of the zeolite-modified and unmodified carbon-paste electrodes (CPEs). ZMCPEs were electrochemically characterized using cyclic voltammetry, chronocoulometry, square-wave voltammetry, and electrochemical impedance spectroscopy. A mechanism for linuron oxidation on ZMCPE surfaces was proposed. The electrochemical variables taken into account were electrode area, number of transferred electrons, electron transfer coefficient, electrode reaction standard rate constant, surface coverage, and capacitance of the electric double layer. Zeolite was found to have a strong influence on these variables. The electrochemical procedure applied to linuron was developed using electrochemically pretreated ZMCPEs under optimal conditions. Linuron oxidation currents exhibited linear concentration in the 87.36 to 625.72 nmol L −1 range, with a limit of detection of 22.57 nmol L −1 . The proposed electrochemical method was employed to quantify linuron in tap and distilled

  8. Surface treatment influences electrochemical stability of cpTi exposed to mouthwashes

    International Nuclear Information System (INIS)

    Beline, Thamara; Garcia, Camila S.; Ogawa, Erika S.; Marques, Isabella S.V.; Matos, Adaias O.; Sukotjo, Cortino; Mathew, Mathew T.

    2016-01-01

    The role of surface treatment on the electrochemical behavior of commercially pure titanium (cpTi) exposed to mouthwashes was tested. Seventy-five disks were divided into 15 groups according to surface treatment (machined, sandblasted with Al 2 O 3 , and acid etched) and electrolyte solution (artificial saliva — control, 0.12% chlorhexidine digluconate, 0.05% cetylpyridinium chloride, 0.2% sodium fluoride, and 1.5% hydrogen peroxide) (n = 5). Open-circuit-potential and electrochemical impedance spectroscopy were conducted at baseline and after 7 and 14 days of immersion in each solution. Potentiodynamic test and total weight loss of disks were performed after 14 days of immersion. Scanning electron microscopy, energy dispersive spectroscopy, white light interferometry and profilometry were conducted for surface characterization before and after the electrochemical tests. Sandblasting promoted the lowest polarization resistance (R p ) (P < .0001) and the highest capacitance (CPE) (P < .006), corrosion current density (I corr ) and corrosion rate (P < .0001). In contrast, acid etching increased R p and reduced CPE, independent to the mouthwash; while hydrogen peroxide reduced R p (P < .008) and increased I corr and corrosion rate (P < .0001). The highest CPE values were found for hydrogen peroxide and 0.2% sodium fluoride. Immersion for longer period improved the electrochemical stability of cpTi (P < .05). In conclusion, acid etching enhanced the electrochemical stability of cpTi. Hydrogen peroxide and sodium fluoride reduced the resistance to corrosion of cpTi, independent to the surface treatment. Chlorhexidine gluconate and cetylpyridinium chloride did not alter the corrosive behavior of cpTi. - Highlights: • Acid etching enhanced the electrochemical stability of cpTi. • Hydrogen peroxide and sodium fluoride reduced the corrosion resistance of cpTi. • Chlorhexidine gluconate and cetylpyridinium chloride can be safely used.

  9. Surface treatment influences electrochemical stability of cpTi exposed to mouthwashes

    Energy Technology Data Exchange (ETDEWEB)

    Beline, Thamara [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); IBTN/Br — Institute of Biomaterials, Tribocorrosion and Nanomedicine, Brazilian Branch (Brazil); Garcia, Camila S. [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); Ogawa, Erika S. [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); IBTN/Br — Institute of Biomaterials, Tribocorrosion and Nanomedicine, Brazilian Branch (Brazil); Marques, Isabella S.V. [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); Matos, Adaias O. [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); IBTN/Br — Institute of Biomaterials, Tribocorrosion and Nanomedicine, Brazilian Branch (Brazil); Sukotjo, Cortino [Department of Restorative Dentistry, University of Illinois at Chicago, College of Dentistry, 801 S Paulina, Chicago, IL 60612 (United States); IBTN — Institute of Biomaterials, Tribocorrosion and Nanomedicine (United States); Mathew, Mathew T. [IBTN — Institute of Biomaterials, Tribocorrosion and Nanomedicine (United States); Department of Orthopedic Surgery, Rush University Medical Center, 1611 W Harrison, Chicago, IL 60612 (United States); and others

    2016-02-01

    The role of surface treatment on the electrochemical behavior of commercially pure titanium (cpTi) exposed to mouthwashes was tested. Seventy-five disks were divided into 15 groups according to surface treatment (machined, sandblasted with Al{sub 2}O{sub 3}, and acid etched) and electrolyte solution (artificial saliva — control, 0.12% chlorhexidine digluconate, 0.05% cetylpyridinium chloride, 0.2% sodium fluoride, and 1.5% hydrogen peroxide) (n = 5). Open-circuit-potential and electrochemical impedance spectroscopy were conducted at baseline and after 7 and 14 days of immersion in each solution. Potentiodynamic test and total weight loss of disks were performed after 14 days of immersion. Scanning electron microscopy, energy dispersive spectroscopy, white light interferometry and profilometry were conducted for surface characterization before and after the electrochemical tests. Sandblasting promoted the lowest polarization resistance (R{sub p}) (P < .0001) and the highest capacitance (CPE) (P < .006), corrosion current density (I{sub corr}) and corrosion rate (P < .0001). In contrast, acid etching increased R{sub p} and reduced CPE, independent to the mouthwash; while hydrogen peroxide reduced R{sub p} (P < .008) and increased I{sub corr} and corrosion rate (P < .0001). The highest CPE values were found for hydrogen peroxide and 0.2% sodium fluoride. Immersion for longer period improved the electrochemical stability of cpTi (P < .05). In conclusion, acid etching enhanced the electrochemical stability of cpTi. Hydrogen peroxide and sodium fluoride reduced the resistance to corrosion of cpTi, independent to the surface treatment. Chlorhexidine gluconate and cetylpyridinium chloride did not alter the corrosive behavior of cpTi. - Highlights: • Acid etching enhanced the electrochemical stability of cpTi. • Hydrogen peroxide and sodium fluoride reduced the corrosion resistance of cpTi. • Chlorhexidine gluconate and cetylpyridinium chloride can be safely used.

  10. High transconductance organic electrochemical transistors

    Science.gov (United States)

    Khodagholy, Dion; Rivnay, Jonathan; Sessolo, Michele; Gurfinkel, Moshe; Leleux, Pierre; Jimison, Leslie H.; Stavrinidou, Eleni; Herve, Thierry; Sanaur, Sébastien; Owens, Róisín M.; Malliaras, George G.

    2013-07-01

    The development of transistors with high gain is essential for applications ranging from switching elements and drivers to transducers for chemical and biological sensing. Organic transistors have become well-established based on their distinct advantages, including ease of fabrication, synthetic freedom for chemical functionalization, and the ability to take on unique form factors. These devices, however, are largely viewed as belonging to the low-end of the performance spectrum. Here we present organic electrochemical transistors with a transconductance in the mS range, outperforming transistors from both traditional and emerging semiconductors. The transconductance of these devices remains fairly constant from DC up to a frequency of the order of 1 kHz, a value determined by the process of ion transport between the electrolyte and the channel. These devices, which continue to work even after being crumpled, are predicted to be highly relevant as transducers in biosensing applications.

  11. Electrochemical processing of carbon dioxide.

    Science.gov (United States)

    Oloman, Colin; Li, Hui

    2008-01-01

    With respect to the negative role of carbon dioxide on our climate, it is clear that the time is ripe for the development of processes that convert CO(2) into useful products. The electroreduction of CO(2) is a prime candidate here, as the reaction at near-ambient conditions can yield organics such as formic acid, methanol, and methane. Recent laboratory work on the 100 A scale has shown that reduction of CO(2) to formate (HCO(2)(-)) may be carried out in a trickle-bed continuous electrochemical reactor under industrially viable conditions. Presuming the problems of cathode stability and formate crossover can be overcome, this type of reactor is proposed as the basis for a commercial operation. The viability of corresponding processes for electrosynthesis of formate salts and/or formic acid from CO(2) is examined here through conceptual flowsheets for two process options, each converting CO(2) at the rate of 100 tonnes per day.

  12. Composite Electrodes for Electrochemical Supercapacitors

    Directory of Open Access Journals (Sweden)

    Yang QuanMin

    2010-01-01

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

  13. Composite Electrodes for Electrochemical Supercapacitors

    Science.gov (United States)

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

    2010-03-01

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

  14. High transconductance organic electrochemical transistors

    Science.gov (United States)

    Khodagholy, Dion; Rivnay, Jonathan; Sessolo, Michele; Gurfinkel, Moshe; Leleux, Pierre; Jimison, Leslie H.; Stavrinidou, Eleni; Herve, Thierry; Sanaur, Sébastien; Owens, Róisín M.; Malliaras, George G.

    2013-01-01

    The development of transistors with high gain is essential for applications ranging from switching elements and drivers to transducers for chemical and biological sensing. Organic transistors have become well-established based on their distinct advantages, including ease of fabrication, synthetic freedom for chemical functionalization, and the ability to take on unique form factors. These devices, however, are largely viewed as belonging to the low-end of the performance spectrum. Here we present organic electrochemical transistors with a transconductance in the mS range, outperforming transistors from both traditional and emerging semiconductors. The transconductance of these devices remains fairly constant from DC up to a frequency of the order of 1 kHz, a value determined by the process of ion transport between the electrolyte and the channel. These devices, which continue to work even after being crumpled, are predicted to be highly relevant as transducers in biosensing applications. PMID:23851620

  15. Mediated electrochemical hazardous waste destruction

    International Nuclear Information System (INIS)

    Hickman, R.G.; Farmer, J.C.; Wang, F.T.

    1991-08-01

    There are few permitted processes for mixed waste (radioactive plus chemically hazardous) treatment. We are developing electrochemical processes that convert the toxic organic components of mixed waste to water, carbon dioxide, an innocuous anions such as chloride. Aggressive oxidizer ions such as Ag 2+ or Ce +4 are produced at an anode. These can attack the organic molecules directly. They can also attack water which yields hydroxyl free radicals that in turn attack the organic molecules. The condensed (i.e., solid and/or liquid) effluent streams contain the inorganic radionuclide forms. These may be treated with existing technology and prepared for final disposal. Kinetics and the extent of destruction of some toxic organics have been measured. Depending on how the process is operated, coulombic efficiency can be nearly 100%. In addition, hazardous organic materials are becoming very expensive to dispose of and when they are combined with transuranic radioactive elements no processes are presently permitted. Mediated electrochemical oxidation is an ambient-temperature aqueous-phase process that can be used to oxidize organic components of mixed wastes. Problems associated with incineration, such as high-temperature volatilization of radionuclides, are avoided. Historically, Ag (2) has been used as a mediator in this process. Fe(6) and Co(3) are attractive alternatives to Ag(2) since they form soluble chlorides during the destruction of chlorinated solvents. Furthermore, silver itself is a toxic heavy metal. Quantitative data has been obtained for the complete oxidation of ethylene glycol by Fe(6) and Co(3). Though ethylene glycol is a nonhalogenated organic, this data has enabled us to make direct comparisons of activities of Fe(6) and Co(3) with Ag(2). Very good quantitative data for the oxidation of ethylene glycol by Ag(2) had already been collected. 4 refs., 6 figs

  16. Electrochemically reduced graphene oxide-based electrochemical sensor for the sensitive determination of ferulic acid in A. sinensis and biological samples

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Linjie [School of Pharmacy, Lanzhou University, Lanzhou 730000 (China); Gou, Yuqiang [Lanzhou Military Command Center for Disease Prevention and Control, Lanzhou 730000 (China); Gao, Xia; Zhang, Pei; Chen, Wenxia; Feng, Shilan [School of Pharmacy, Lanzhou University, Lanzhou 730000 (China); Hu, Fangdi, E-mail: hufd@lzu.edu.cn [School of Pharmacy, Lanzhou University, Lanzhou 730000 (China); Li, Yingdong, E-mail: lydj412@163.com [Gansu College of Tradition Chinese Medicine, Lanzhou 730000 (China)

    2014-09-01

    An electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE) was used as a new voltammetric sensor for the determination of ferulic acid (FA). The morphology and microstructure of the modified electrodes were characterized by scanning electron microscopy (SEM) and Raman spectroscopy analysis, and the electrochemical effective surface areas of the modified electrodes were also calculated by chronocoulometry method. Sensing properties of the electrochemical sensor were investigated by means of cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that ERGO was electrodeposited on the surface of GCE by using potentiostatic method. The proposed electrode exhibited electrocatalytic activity to the redox of FA because of excellent electrochemical properties of ERGO. The transfer electron number (n), electrode reaction rate constant (k{sub s}) and electron-transfer coefficient (α) were calculated as 1.12, 1.24 s{sup −1}, and 0.40, respectively. Under the optimized conditions, the oxidation peak current was proportional to FA concentration at 8.49 × 10{sup −8} mol L{sup −1} to 3.89 × 10{sup −5} mol L{sup −1} with detection limit of 2.06 × 10{sup −8} mol L{sup −1}. This fabricated sensor also displayed acceptable reproducibility, long-term stability, and high selectivity with negligible interferences from common interfering species. The voltammetric sensor was successfully applied to detect FA in A. sinensis and biological samples with recovery values in the range of 99.91%-101.91%. - Highlights: • A novel ERGO–based electrochemical sensor of FA was successfully fabricated by using one-step electrodeposition method. • The electrode reaction was an adsorption–diffusion mixed controlled process. • The low detection limit with good selectivity and sensitivity were obtained. • This method was applied for the determination of FA in A. sinensis and biological samples.

  17. Enhancing the water oxidation activity of Ni2P nanocatalysts by iron-doping and electrochemical activation

    International Nuclear Information System (INIS)

    Liu, Guang; He, Dongying; Yao, Rui; Zhao, Yong; Li, Jinping

    2017-01-01

    Highlights: •A sol-gel method for synthesis of Fe-doping Ni 2 P nanocatalysts was present. •Fe-doping Ni 2 P sample exhibited high OER activity after electrochemical activation. •In situ formed Fe-NiOOH layer on activated Fe-Ni 2 P provided more active OER sites. -- Abstract: In this work, we reported a facile and safe route for synthesis of Ni 2 P nanocatalysts by sol-gel method and demonstrated that the oxygen evolution reaction (OER) activity of Ni 2 P nanocatalysts can be dramatically enhanced by iron-doping and electrochemical activation. Compared with the fresh Fe-doped Ni 2 P nanocatalysts, a stable Fe-NiOOH layer was formed on the surface of Fe-doped Ni 2 P nanoparticles by electrochemical activation, thus promoting the charge transfer ability and surface electrochemically active sites generation for the electrochemical activated Fe-doped Ni 2 P nanocatalysts, ultimately accounting for the improvement of water oxidation activity, which was evidenced by cyclic voltammograms (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectra (XPS) as well as high-resolution transmission electron microscopy (HR-TEM) measurements. For water oxidation reaction in 1 M KOH solution, the electrochemical activated Fe-doped Ni 2 P nanocatalysts can attain 10 mA/cm 2 at an overpotential of 292 mV with Tafel slope of 50 mV/dec, which was also much better than that of individual Ni 2 P, Fe 2 P nanocatalysts as well as commercial RuO 2 electrocatalyst. Moreover, long-term stability performance by chronoamperometric and chronopotentiometric tests for the activated Fe-doped Ni 2 P nanocatalysts exhibited no obvious decline within 56 h. It was demonstrated that modulating the OER catalytic activity for metal phosphide by iron-doping and electrochemical activation may provide new opportunities and avenues to engineer high performance electrocatalysts for water splitting.

  18. Electrochemical Approaches to Renewable Energy

    Science.gov (United States)

    Lobaccaro, Peter

    Renewable energy is becoming an increasingly important component of the world's energy supply as the threat of global warming continues to rise. There is a need to reduce the cost of this renewable energy and a future challenge to deal with the strain intermittent power sources like renewables place on the power grid. In this dissertation, electrochemistry is harnessed to address possible solutions to both of these issues. First, it is used to develop a low cost alternative photovoltaic material. Then, it is used to investigate the production of chemical fuel stocks which can be used for energy storage. In chapter 2, advances are made in the electrochemical deposition of indium (In) on molybdenum foil which enables the deposition of electronic-grade purity, continuous films with thicknesses in the micron range. As an example application, the electrodeposited In films are phosphorized via the thin-film vapor-liquid-solid growth method. The resulting poly-crystalline InP films display excellent optoelectronic quality, comparable to films grown from more standard vacuum deposition techniques. This demonstrates the versatility of the developed electrochemical deposition procedure. In the remaining chapters, renewable fuel production is investigated. First in chapter 3, molybdenum disulfide (MoS2) is examined as a catalyst for the hydrogen evolution reaction (HER). Typically, high-cost synthesized MoS2 is used as the catalyst because the pristine MoS 2 mineral is known to be a poor catalyst. The fundamental challenge with pristine MoS2 is the inert HER activity of the predominant (0001) basal surface plane. Here, we report a general thermal process in which the basal plane is texturized to increase the density of HER-active edge sites. The process generates high HER catalytic performance in pristine MoS 2 across various morphologies such as the bulk mineral, films composed of micron-scale flakes, and even films of a commercially-available spray of nanoflake MoS2. In

  19. Electron transport determines the electrochemical properties of tetrahedral amorphous carbon (ta-C) thin films

    International Nuclear Information System (INIS)

    Palomäki, Tommi; Wester, Niklas; Caro, Miguel A.; Sainio, Sami; Protopopova, Vera; Koskinen, Jari; Laurila, Tomi

    2017-01-01

    Amorphous carbon based electrodes are very promising for electrochemical sensing applications. In order to better understand their structure-function relationship, the effect of film thickness on the electrochemical properties of tetrahedral amorphous carbon (ta-C) electrodes was investigated. ta-C thin films of 7, 15, 30, 50 and 100 nm were characterized in detail with Raman spectroscopy, transmission electron microscopy (TEM), conductive atomic force microscopy (c-AFM), scanning tunneling spectroscopy (STS) and X-ray absorption spectroscopy (XAS) to assess (i) the surface properties of the films, (ii) the effect of film thickness on their structure and electrical properties and (iii) the subsequent correlation with their electrochemistry. The electrochemical properties were investigated by cyclic voltammetry (CV) using two different outer-sphere redox probes, Ru(NH 3 ) 6 3+/2+ and FcMeOH, and by electrochemical impedance spectroscopy (EIS). Computational simulations using density functional theory (DFT) were carried out to rationalize the experimental findings. The characterization results showed that the sp 2 /sp 3 ratio increased with decreasing ta-C film thickness. This correlated with a decrease in mobility gap value and an increase in the average current through the films, which was also consistent with the computational results. XAS indicated that the surface of the ta-C films was always identical and composed of a sp 2 -rich layer. The CV measurements indicated reversible reaction kinetics for both outer-sphere redox probes at 7 and 15 nm ta-C films with a change to quasi-reversible behavior at a thickness of around 30 nm. The charge transfer resistance, obtained from EIS measurements, decreased with decreasing film thickness in accordance with the CV results. Based on the characterization and electrochemical results, we conclude that the reaction kinetics in the case of outer-sphere redox systems is determined mainly by the electron transport through the

  20. Building micro and nanosystems with electrochemical discharges

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-11-30

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

  1. Building micro and nanosystems with electrochemical discharges

    International Nuclear Information System (INIS)

    Wuethrich, Rolf; Allagui, Anis

    2010-01-01

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

  2. Process for electrochemically gasifying coal using electromagnetism

    Science.gov (United States)

    Botts, Thomas E.; Powell, James R.

    1987-01-01

    A process for electrochemically gasifying coal by establishing a flowing stream of coal particulate slurry, electrolyte and electrode members through a transverse magnetic field that has sufficient strength to polarize the electrode members, thereby causing them to operate in combination with the electrolyte to electrochemically reduce the coal particulate in the slurry. Such electrochemical reduction of the coal produces hydrogen and carbon dioxide at opposite ends of the polarized electrode members. Gas collection means are operated in conjunction with the process to collect the evolved gases as they rise from the slurry and electrolyte solution.

  3. Electrochemical cell structure including an ionomeric barrier

    Science.gov (United States)

    Lambert, Timothy N.; Hibbs, Michael

    2017-06-20

    An apparatus includes an electrochemical half-cell comprising: an electrolyte, an anode; and an ionomeric barrier positioned between the electrolyte and the anode. The anode may comprise a multi-electron vanadium phosphorous alloy, such as VP.sub.x, wherein x is 1-5. The electrochemical half-cell is configured to oxidize the vanadium and phosphorous alloy to release electrons. A method of mitigating corrosion in an electrochemical cell includes disposing an ionomeric barrier in a path of electrolyte or ion flow to an anode and mitigating anion accumulation on the surface of the anode.

  4. Electrochemical ammonia production on molybdenum nitride nanoclusters

    DEFF Research Database (Denmark)

    Howalt, Jakob Geelmuyden; Vegge, Tejs

    2013-01-01

    Theoretical investigations of electrochemical production of ammonia at ambient temperature and pressure on nitrogen covered molybdenum nanoparticles are presented. Density functional theory calculations are used in combination with the computational hydrogen electrode approach to calculate the free...... energy profile for electrochemical protonation of N2 and N adatoms on cuboctahedral Mo13 nanoparticles. Pathways for electrochemical ammonia production via direct protonation of N adatoms and N2 admolecules with an onset potential as low as -0.5 V and generally lower than -0.8 V on both a nitrogen...

  5. Electrochemical desalination of historic Portuguese tiles

    DEFF Research Database (Denmark)

    Ottosen, Lisbeth M.; Dias-Ferreira, Celia; Ribeiro, Alexandra B.

    2015-01-01

    Soluble salts cause severe decay of historic Portuguese tiles. Treatment options for removal of the salts to stop the decay are few. The present paper deals with development of a method for electrochemical desalination, where an electric DC field is applied to the tiles. Laboratory experiments were...... the electrochemical treatment. The removal rate was similar for the two anions so the chloride concentration reached the lowest concentration level first. At this point the electric resistance increased, but the removal of nitrate continued unaffected till similar low concentration. The sulfate concentration...... was successful. Based on the obtained results an important step is taken towards development of an electrochemical technique for desalination of tile panels....

  6. Electrochemical remediation of copper contaminated clay soils

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-07-01

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

  7. Spectro-electrochemical and DFT study of tenoxicam metabolites formed by electrochemical oxidation

    International Nuclear Information System (INIS)

    Ramírez-Silva, M.T.; Guzmán-Hernández, D.S.; Galano, A.; Rojas-Hernández, A.; Corona-Avendaño, S.; Romero-Romo, M.; Palomar-Pardavé, M.

    2013-01-01

    Highlights: • Tenoxicam deprotonation and electrochemical oxidation were studied. • Both spectro-electrochemical and theoretical DFT studies were considered. • It was found that the ampholitic species of tenoxicam is a zwitterion. • Electrochemical oxidation of tenoxicam yields two non-electroactive products. • The nature of these fragments was further confirmed by a chromatography study. -- Abstract: From experimental (spectro-electrochemical) and theoretical (DFT) studies, the mechanisms of tenoxicam deprotonation and electrochemical oxidation were assessed. From these studies, new insights on the nature of the ampholitic species involved during tenoxicam's deprotonation in aqueous solution are presented; see scheme A. Moreover, it is shown that, after the analysis of two different reaction schemes that involve up to 10 different molecules and 12 reaction paths, the electrochemical oxidation of tenoxicam, yields two non-electroactive products that are predominately formed by its fragmentation, after the loss of two electrons. The nature of these fragments was further confirmed by a chromatography study

  8. Electrodeposition synthesis and electrochemical properties of nanostructured γ-MnO 2 films

    Science.gov (United States)

    Chou, Shulei; Cheng, Fangyi; Chen, Jun

    The thin films of carambola-like γ-MnO 2 nanoflakes with about 20 nm in thickness and at least 200 nm in width were prepared on nickel sheets by combination of potentiostatic and cyclic voltammetric electrodeposition techniques. The as-prepared MnO 2 nanomaterials, which were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), were used as the active material of the positive electrode for primary alkaline Zn/MnO 2 batteries and electrochemical supercapacitors. Electrochemical measurements showed that the MnO 2 nanoflake films displayed high potential plateau (around 1.0 V versus Zn) in primary Zn/MnO 2 batteries at the discharge current density of 500 mA g -1 and high specific capacitance of 240 F g -1 at the current density of 1 mA cm -2. This indicated the potential application of carambola-like γ-MnO 2 nanoflakes in high-power batteries and electrochemical supercapacitors. The growth process for the one- and three-dimensional nanostructured MnO 2 was discussed on the basis of potentiostatic and cyclic voltammetric techniques. The present synthesis method can be extended to the preparation of other nanostructured metal-oxide films.

  9. Graphene prepared by one-pot solvent exfoliation as a highly sensitive platform for electrochemical sensing

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Can; Cheng, Qin [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Wu, Kangbing, E-mail: kbwu@hust.edu.cn [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Wu, Gang [Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Li, Qing, E-mail: qing_li_2@brown.edu [Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2014-05-01

    Highlights: • Graphene was prepared by one-step solvent exfoliation as superior electrode material. • Compared with RGO, prepared graphene exhibited stronger signal enhancement. • A widespread and highly-sensitive electrochemical sensing platform was constructed. - Abstract: Graphene was easily obtained via one-step ultrasonic exfoliation of graphite powder in N-methyl-2-pyrrolidone. Scanning electron microscopy, transmission electron microscopy, Raman and particle size measurements indicated that the exfoliation efficiency and the amount of produced graphene increased with ultrasonic time. The electrochemical properties and analytical applications of the resulting graphene were systematically studied. Compared with the predominantly-used reduced graphene oxides, the obtained graphene by one-step solvent exfoliation greatly enhanced the oxidation signals of various analytes, such as ascorbic acid (AA), dopamine (DA), uric acid (UA), xanthine (XA), hypoxanthine (HXA), bisphenol A (BPA), ponceau 4R, and sunset yellow. The detection limits of AA, DA, UA, XA, HXA, BPA, ponceau 4R, and sunset yellow were evaluated to be 0.8 μM, 7.5 nM, 2.5 nM, 4 nM, 10 nM, 20 nM, 2 nM, and 1 nM, which are much lower than the reported values. Thus, the prepared graphene via solvent exfoliation strategy displays strong signal amplification ability and holds great promise in constructing a universal and sensitive electrochemical sensing platform.

  10. Effect of Ce addition on the mechanical and electrochemical properties of a lithium battery shell alloy

    International Nuclear Information System (INIS)

    Zhang, Junchao; Ding, Dongyan; Xu, Xinglong; Gao, Yongjin; Chen, Guozhen; Chen, Weigao; You, Xiaohua; Huang, Yuanwei; Tang, Jinsong

    2014-01-01

    Highlights: • Fabrication of Ce-free and Ce-containing Al–Cu–Mn–Fe–Mg alloy. • TEM, tensile and electrochemical characterization of the alloys. • Ce element greatly affects the precipitation of the alloy. • Ce element had great impact on the tensile strength and corrosion potential of the alloys. - Abstract: Due to severe application environment lithium battery shell of new-energy automotives requires increasing demands for using high performance aluminum alloys. In the present work, effect of Ce addition on the microstructure, tensile and electrochemical properties of an Al–Cu–Mn–Mg–Fe alloy were investigated through using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), tensile tests and electrochemical tests. The experimental results indicated that the addition of Ce element could promote the precipitation of second phases. With addition of 0.36% Ce, high melting point Al 8 Cu 4 Ce phase and many Al 20 Cu 2 Mn 3 particles could be found. In addition, the precipitation of conventionally dominant phase of Al 2 Cu could be suppressed in alloy. The Ce addition was found to result in enhanced tensile strength and improved corrosion resistance

  11. Self-assembled hierarchical graphene/polyaniline hybrid aerogels for electrochemical capacitive energy storage

    International Nuclear Information System (INIS)

    Yang, Fan; Xu, Maowen; Bao, Shu-Juan; Wei, Hua; Chai, Hui

    2014-01-01

    In this work, polyaniline nanowires (PANI-NWs) act as spacers, incorporated with graphene oxide and self-assembled into graphene/PANI hybrid aerogels through a facile hydrothermal route. The as-synthesized samples have been characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS), contact angle measurement, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) for their microstructure, morphology and relative affinities toward water. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements have been used to study the effects of composition, microstructure and morphology of the samples on their capacitive performance. The experimental results indicate that the PANI can effectively tailor the microstructures and electrochemical performances of the products. The as-prepared materials with an appropriate proportion of PANI nanowires can efficiently prevent the adjacent graphene sheets from aggregation and provide fast ionic channels for electrochemical energy storage. A specific capacitance of 520.3 F g −1 has been achieved from graphene/PANI hybrid aerogel, which also exhibits excellent cycling stability

  12. Effect of Ce addition on the mechanical and electrochemical properties of a lithium battery shell alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Junchao [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Ding, Dongyan, E-mail: dyding@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Xu, Xinglong [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Gao, Yongjin; Chen, Guozhen; Chen, Weigao; You, Xiaohua [Huafon NLM Al Co., Ltd, Shanghai 201506 (China); Huang, Yuanwei; Tang, Jinsong [Shanghai Huafon Materials Technology Institute, Shanghai 201203 (China)

    2014-12-25

    Highlights: • Fabrication of Ce-free and Ce-containing Al–Cu–Mn–Fe–Mg alloy. • TEM, tensile and electrochemical characterization of the alloys. • Ce element greatly affects the precipitation of the alloy. • Ce element had great impact on the tensile strength and corrosion potential of the alloys. - Abstract: Due to severe application environment lithium battery shell of new-energy automotives requires increasing demands for using high performance aluminum alloys. In the present work, effect of Ce addition on the microstructure, tensile and electrochemical properties of an Al–Cu–Mn–Mg–Fe alloy were investigated through using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), tensile tests and electrochemical tests. The experimental results indicated that the addition of Ce element could promote the precipitation of second phases. With addition of 0.36% Ce, high melting point Al{sub 8}Cu{sub 4}Ce phase and many Al{sub 20}Cu{sub 2}Mn{sub 3} particles could be found. In addition, the precipitation of conventionally dominant phase of Al{sub 2}Cu could be suppressed in alloy. The Ce addition was found to result in enhanced tensile strength and improved corrosion resistance.

  13. Modified glassy carbon electrodes based on carbon nanostructures for ultrasensitive electrochemical determination of furazolidone

    Energy Technology Data Exchange (ETDEWEB)

    Shahrokhian, Saeed, E-mail: shahrokhian@sharif.edu [Department of Chemistry, Sharif University of Technology, Tehran 11155-9516 (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Naderi, Leila [Department of Chemistry, Sharif University of Technology, Tehran 11155-9516 (Iran, Islamic Republic of); Ghalkhani, Masoumeh [Department of Chemistry, Faculty of Science, Shahid Rajaee Teacher Training University, Lavizan, Tehran (Iran, Islamic Republic of); Institute for advanced technology, Shahid Rajaee Teacher Training University, Lavizan, Tehran, 16788 (Iran, Islamic Republic of)

    2016-04-01

    The electrochemical behavior of Furazolidone (Fu) was investigated on the surface of the glassy carbon electrode modified with different carbon nanomaterials, including carbon nanotubes (CNTs), carbon nanoparticles (CNPs), nanodiamond-graphite (NDG), graphene oxide (GO), reduced graphene oxide (RGO) and RGO-CNT hybrids (various ratios) using linear sweep voltammetry (LSV). The results of voltammetric studies exhibited a considerable increase in the cathodic peak current of Fu at the RGO modified GCE, compared to other modified electrodes and also bare GCE. The surface morphology and nature of the RGO film was thoroughly characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The modified electrode showed two linear dynamic ranges of 0.001–2.0 μM and 2.0–10.0 μM with a detection limit of 0.3 nM for the voltammetric determination of Fu. This sensor was used successfully for Fu determination in pharmaceutical and clinical preparations. - Highlights: • The electrochemical behavior of Furazolidone (Fu) was investigated on the surface of the modified electrode with different carbon nanomaterials by Linear sweep voltammetry. • Two linear dynamic ranges and a low detection limit were obtained. • The modified electrode was applied for the detection of Fu in pharmaceutical and clinical preparations.

  14. Chitosan-iron oxide nanocomposite based electrochemical aptasensor for determination of malathion

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakar, Nirmal, E-mail: nirmalprabhakar@gmail.com; Thakur, Himkusha; Bharti, Anu; Kaur, Navpreet

    2016-10-05

    An electrochemical aptasensor based on chitosan-iron oxide nanocomposite (CHIT-IO) film deposited on fluorine tin Oxide (FTO) was developed for the detection of malathion. Iron oxide nanoparticles were prepared by co-precipitation method and characterized by Transmission electron microscopy and UV–Visible spectroscopy. The biotinylated DNA aptamer sequence specific to the malathion was immobilized onto the iron oxide doped-chitosan/FTO electrode by using streptavidin as linking molecule. Various characterization studies like Field Emission-Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and Electrochemical studies were performed to attest the successful fabrication of bioelectrodes. Experimental parameters like aptamer concentration, response time, stability of electrode and reusability studies were optimized. Aptamer immobilized chitosan-iron oxide nanocomposite (APT/SA/CHIT-IO/FTO) bioelectrodes exhibited LOD of about 0.001 ng/mL within 15 min and spike-in studies revealed about 80–92% recovery of malathion from the lettuce leaves and soil sample. - Highlights: • An electrochemical aptasensor for the detection of Malathion has been developed. • Chitosan-iron oxide NP deposited FTO sheets provides platform for aptamer immobilization. • Aptasensor has efficiency to detect malathion upto 0.001 ng/mL within 15 min.

  15. Electrodeposition synthesis and electrochemical properties of nanostructured {gamma}-MnO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Shulei; Cheng, Fangyi; Chen, Jun [Institute of New Energy Material Chemistry, Nankai University, Tianjin 300071 (China)

    2006-11-08

    The thin films of carambola-like {gamma}-MnO{sub 2} nanoflakes with about 20nm in thickness and at least 200nm in width were prepared on nickel sheets by combination of potentiostatic and cyclic voltammetric electrodeposition techniques. The as-prepared MnO{sub 2} nanomaterials, which were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), were used as the active material of the positive electrode for primary alkaline Zn/MnO{sub 2} batteries and electrochemical supercapacitors. Electrochemical measurements showed that the MnO{sub 2} nanoflake films displayed high potential plateau (around 1.0V versus Zn) in primary Zn/MnO{sub 2} batteries at the discharge current density of 500mAg{sup -1} and high specific capacitance of 240Fg{sup -1} at the current density of 1mAcm{sup -2}. This indicated the potential application of carambola-like {gamma}-MnO{sub 2} nanoflakes in high-power batteries and electrochemical supercapacitors. The growth process for the one- and three-dimensional nanostructured MnO{sub 2} was discussed on the basis of potentiostatic and cyclic voltammetric techniques. The present synthesis method can be extended to the preparation of other nanostructured metal-oxide films. (author)

  16. High-resolution intravital microscopy.

    Directory of Open Access Journals (Sweden)

    Volker Andresen

    Full Text Available Cellular communication constitutes a fundamental mechanism of life, for instance by permitting transfer of information through synapses in the nervous system and by leading to activation of cells during the course of immune responses. Monitoring cell-cell interactions within living adult organisms is crucial in order to draw conclusions on their behavior with respect to the fate of cells, tissues and organs. Until now, there is no technology available that enables dynamic imaging deep within the tissue of living adult organisms at sub-cellular resolution, i.e. detection at the level of few protein molecules. Here we present a novel approach called multi-beam striped-illumination which applies for the first time the principle and advantages of structured-illumination, spatial modulation of the excitation pattern, to laser-scanning-microscopy. We use this approach in two-photon-microscopy--the most adequate optical deep-tissue imaging-technique. As compared to standard two-photon-microscopy, it achieves significant contrast enhancement and up to 3-fold improved axial resolution (optical sectioning while photobleaching, photodamage and acquisition speed are similar. Its imaging depth is comparable to multifocal two-photon-microscopy and only slightly less than in standard single-beam two-photon-microscopy. Precisely, our studies within mouse lymph nodes demonstrated 216% improved axial and 23% improved lateral resolutions at a depth of 80 µm below the surface. Thus, we are for the first time able to visualize the dynamic interactions between B cells and immune complex deposits on follicular dendritic cells within germinal centers (GCs of live mice. These interactions play a decisive role in the process of clonal selection, leading to affinity maturation of the humoral immune response. This novel high-resolution intravital microscopy method has a huge potential for numerous applications in neurosciences, immunology, cancer research and

  17. High-Resolution Intravital Microscopy

    Science.gov (United States)

    Andresen, Volker; Pollok, Karolin; Rinnenthal, Jan-Leo; Oehme, Laura; Günther, Robert; Spiecker, Heinrich; Radbruch, Helena; Gerhard, Jenny; Sporbert, Anje; Cseresnyes, Zoltan; Hauser, Anja E.; Niesner, Raluca

    2012-01-01

    Cellular communication constitutes a fundamental mechanism of life, for instance by permitting transfer of information through synapses in the nervous system and by leading to activation of cells during the course of immune responses. Monitoring cell-cell interactions within living adult organisms is crucial in order to draw conclusions on their behavior with respect to the fate of cells, tissues and organs. Until now, there is no technology available that enables dynamic imaging deep within the tissue of living adult organisms at sub-cellular resolution, i.e. detection at the level of few protein molecules. Here we present a novel approach called multi-beam striped-illumination which applies for the first time the principle and advantages of structured-illumination, spatial modulation of the excitation pattern, to laser-scanning-microscopy. We use this approach in two-photon-microscopy - the most adequate optical deep-tissue imaging-technique. As compared to standard two-photon-microscopy, it achieves significant contrast enhancement and up to 3-fold improved axial resolution (optical sectioning) while photobleaching, photodamage and acquisition speed are similar. Its imaging depth is comparable to multifocal two-photon-microscopy and only slightly less than in standard single-beam two-photon-microscopy. Precisely, our studies within mouse lymph nodes demonstrated 216% improved axial and 23% improved lateral resolutions at a depth of 80 µm below the surface. Thus, we are for the first time able to visualize the dynamic interactions between B cells and immune complex deposits on follicular dendritic cells within germinal centers (GCs) of live mice. These interactions play a decisive role in the process of clonal selection, leading to affinity maturation of the humoral immune response. This novel high-resolution intravital microscopy method has a huge potential for numerous applications in neurosciences, immunology, cancer research and developmental biology

  18. Carbon nanotubes modified with antimony nanoparticles: A novel material for electrochemical sensing

    International Nuclear Information System (INIS)

    Moraes, Fernando C.; Cesarino, Ivana; Cesarino, Vivian; Mascaro, Lucia H.; Machado, Sergio A.S.

    2012-01-01

    Highlights: ► A novel material for the electrochemical sensing was developed. ► Sensor based CNTs modified with Sb-nanoparticles was characterised and applied. ► The proposed sensor was suitable and sensitive for the determination of bisphenol A. - Abstract: In this study, a novel material for the electrochemical determination of bisphenol A using a nanocomposite based on multi-walled carbon nanotubes modified with antimony nanoparticles has been investigated. The morphology, structure, and electrochemical performance of the nanocomposite electrodes were characterised by field emission gun scanning electron microscopy, energy-dispersive X-ray spectroscopy, and cyclic voltammetry. A scan rate study and electrochemical impedance spectroscopy showed that the bisphenol A oxidation product is adsorbed on nanocomposite electrode surface. Differential pulse voltammetry in phosphate buffer solution at pH 6, allowed the development of a method to determine bisphenol A levels in the range of 0.5–5.0 μmol L −1 , with a detection limit of 5.24 nmol L −1 (1.19 μg L −1 ).

  19. Fabrication and characterization of electrochemically prepared bioanode (polyaniline/ferritin/glucose oxidase) for biofuel cell application

    Science.gov (United States)

    ul Haque, Sufia; Inamuddin; Nasar, Abu; Asiri, Abdullah M.

    2018-01-01

    Porous matrix of polyaniline (PANI) has been electrodeposited along with the entrapment of biocompatible redox mediator ferritin (Frt) and glucose oxidase (GOx) on the surface of glassy carbon (GC) electrode. The characterizations have been carried out by X-ray Diffraction (XRD) and Transmission electron microscopy (TEM). The enhanced electrochemical signal transfer rate from enzyme to the electrode surface was due to the intimate contact of the enzyme with the electrochemically polymerized conducting PANI matrix. The PANI/Frt/GOx modified GC bioanode was used to investigate the electrocatalytic activity as a function of the concentration of glucose in the range of 10-60 mM. It was confirmed by the electrochemical impedance spectroscopy (EIS), the thick deposition of PANI layer becomes more compact due to which the charge transfer resistance of PANI matrix becomes higher. All the electrochemical measurements of the electrode were carried out by using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). CV curves were recorded at different scan rates (20-100 mV/s) at 50 mM of glucose in 0.3 M potassium ferrocyanide. A normalized saturation current density of 22.3 ± 2 mA/cm2 was observed for the oxidation of 50 mM glucose at a scan rate of 100 mV/s.

  20. Preparation and electrochemical performances of nanoporous/cracked cobalt oxide layer for supercapacitors

    Science.gov (United States)

    Gobal, Fereydoon; Faraji, Masoud

    2014-12-01

    Nanoporous/cracked structures of cobalt oxide (Co3O4) electrodes were successfully fabricated by electroplating of zinc-cobalt onto previously formed TiO2 nanotubes by anodizing of titanium, leaching of zinc in a concentrated alkaline solution and followed by drying and annealing at 400 °C. The structure and morphology of the obtained Co3O4 electrodes were characterized by X-ray diffraction, EDX analysis and scanning electron microscopy. The results showed that the obtained Co3O4 electrodes were composed of the nanoporous/cracked structures with an average pore size of about 100 nm. The electrochemical capacitive behaviors of the nanoporous Co3O4 electrodes were investigated by cyclic voltammetry, galvanostatic charge-discharge studies and electrochemical impedance spectroscopy in 1 M NaOH solution. The electrochemical data demonstrated that the electrodes display good capacitive behavior with a specific capacitance of 430 F g-1 at a current density of 1.0 A g-1 and specific capacitance retention of ca. 80 % after 10 days of being used in electrochemical experiments, indicating to be promising electroactive materials for supercapacitors. Furthermore, in comparison with electrodes prepared by simple cathodic deposition of cobalt onto TiO2 nanotubes(without dealloying procedure), the impedance studies showed improved performances likely due to nanoporous/cracked structures of electrodes fabricated by dealloying of zinc, which provide fast ion and electron transfer routes and large reaction surface area with the ensued fast reaction kinetics.

  1. Electrochemical behavior of an anticancer drug 5-fluorouracil at methylene blue modified carbon paste electrode

    International Nuclear Information System (INIS)

    Bukkitgar, Shikandar D.; Shetti, Nagaraj P.

    2016-01-01

    A novel sensor for the determination of 5-fluorouracil was constructed by electrochemical deposition of methylene blue on surface of carbon paste electrode. The electrode surface morphology was studied using Atomic force microscopy and XRD. The electrochemical activity of modified electrode was characterized using cyclic voltammetry and differential pulse method. The developed sensor shows impressive enlargement in sensitivity of 5-fluorouracil determination. The peak currents obtained from differential pulse voltammetry was linear with concentration of 5-fluorouracil in the range 4 × 10 −5 –1 × 10 −7 M and detection limit and quantification limit were calculated to be 2.04 nM and 6.18 nM respectively. Further, the sensor was successfully applied in pharmaceutical and biological fluid sample analysis. - Highlights: • Electrochemical oxidation of 5-fluorouracil has been investigated for first time at methylene blue modified carbon paste electrode • The electrode process was irreversible and diffusion controlled • Probable electrochemical mechanism was proposed which involved two proton and two electron transfer reaction • The LOD and LOQ values were calculated to be 2.04 nM and 6.18 nM, respectively, with good selectivity and sensitivity. • Proposed method was applied to 5-Fluorouracil determination in pharmaceutical and spiked human urine samples

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

    Science.gov (United States)

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

    2016-05-01

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

  3. Electrochemical Polishing Applications and EIS of a Vitamin B4-Based Ionic Liquid

    International Nuclear Information System (INIS)

    Wixtrom, Alex I.; Buhler, Jessica E.; Reece, Charles E.; Abdel-Fattah, Tarek M.

    2013-01-01

    Modern particle accelerators require minimal interior surface roughness for Niobium superconducting radio frequency (SRF) cavities. Polishing of the Nb is currently achieved via electrochemical polishing with concentrated mixtures of sulfuric and hydrofluoric acids. This acid-based approach is effective at reducing the surface roughness to acceptable levels for SRF use, but due to acid-related hazards and extra costs (including safe disposal of used polishing solutions), an acid-free method would be preferable. This study focuses on an alternative electrochemical polishing method for Nb, using a novel ionic liquid solution containing choline chloride, also known as Vitamin B 4 (VB 4 ). Potentiostatic electrochemical impedance spectroscopy (EIS) was also performed on the VB4-based system. Nb polished using the VB4-based method was found to have a final surface roughness comparable to that achieved via the acid-based method, as assessed by atomic force microscopy (AFM). These findings indicate that acid-free VB 4 -based electrochemical polishing of Nb represents a promising replacement for acid-based methods of SRF cavity preparation

  4. Electrochemical corrosion behavior of a Ti-35Nb alloy for medical prostheses

    International Nuclear Information System (INIS)

    Cremasco, Alessandra; Osorio, Wislei R.; Freire, Celia M.A.; Garcia, Amauri; Caram, Rubens

    2008-01-01

    Since the 1980s, the titanium alloys show attractive properties for biomedical applications where the most important factors are, firstly, biocompatibility, corrosion and mechanical resistances, low modulus of elasticity, very good strength to weight ratio, reasonable formability and osseointegration. The aim of this study was to investigate the effects of two different heat treatments; furnace cooling and water quenching, on the general electrochemical corrosion resistance of Ti-35 wt%Nb alloy samples immersed in a 0.9% NaCl (0.15 mol L -1 ) solution at 25 deg. C and neutral pH range. The samples were obtained using a non-consumable tungsten electrode furnace with a water-cooled copper hearth under argon atmosphere. The microstructural pattern was examined by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). In order to evaluate the electrochemical corrosion behavior of such Ti-Nb alloy samples, corrosion tests were performed by using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. Analyses of an equivalent circuit have also been used to provide quantitative support for the discussions and understanding of the corrosion behavior. It was found that water quenching provides a microstructural pattern consisting of an alpha-martensite acicular phase which decreases the material electrochemical performance due to the stress-induced martensitic transformation

  5. Electrochemical corrosion behavior of a Ti-35Nb alloy for medical prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Cremasco, Alessandra [Department of Materials Engineering, State University of Campinas, UNICAMP, P.O. Box 6122, 13083-970 Campinas, SP (Brazil); Osorio, Wislei R. [Department of Materials Engineering, State University of Campinas, UNICAMP, P.O. Box 6122, 13083-970 Campinas, SP (Brazil)], E-mail: wislei@fem.unicamp.br; Freire, Celia M.A.; Garcia, Amauri; Caram, Rubens [Department of Materials Engineering, State University of Campinas, UNICAMP, P.O. Box 6122, 13083-970 Campinas, SP (Brazil)

    2008-05-30

    Since the 1980s, the titanium alloys show attractive properties for biomedical applications where the most important factors are, firstly, biocompatibility, corrosion and mechanical resistances, low modulus of elasticity, very good strength to weight ratio, reasonable formability and osseointegration. The aim of this study was to investigate the effects of two different heat treatments; furnace cooling and water quenching, on the general electrochemical corrosion resistance of Ti-35 wt%Nb alloy samples immersed in a 0.9% NaCl (0.15 mol L{sup -1}) solution at 25 deg. C and neutral pH range. The samples were obtained using a non-consumable tungsten electrode furnace with a water-cooled copper hearth under argon atmosphere. The microstructural pattern was examined by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). In order to evaluate the electrochemical corrosion behavior of such Ti-Nb alloy samples, corrosion tests were performed by using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. Analyses of an equivalent circuit have also been used to provide quantitative support for the discussions and understanding of the corrosion behavior. It was found that water quenching provides a microstructural pattern consisting of an alpha-martensite acicular phase which decreases the material electrochemical performance due to the stress-induced martensitic transformation.

  6. In situ electrochemical etching and examination by SPM of titanate ceramics

    International Nuclear Information System (INIS)

    Thorogood, G.J.; Short, K.T; Zhang, Y.

    2002-01-01

    Full text: The aqueous durability of titanate related ceramics is of great importance for the immobilisation of high level radioactive waste-in order to observe the reaction progress at the solid-liquid interface of these durable ceramics, we have attempted to accelerate the dissolution process via electrochemical means by using a SPM cell with electrochemical capability. The experiment involves placing a titanate ceramic disk (with flat polished surfaces) in the electrochemical cell. The cell is then set up with the ceramic acting as one electrode and another electrode being placed in the solution. In a flow through cell it is possible to select the pH and observe the change, not only in surface morphology as dissolution occurs, but also the frictional characteristics of the surface. The SPM tip plays no role in the electrochemical reaction. We will be presenting results from our work and discussing possible mechanisms for dissolution and future directions of the work. Copyright (2002) Australian Society for Electron Microscopy Inc

  7. Production and characterization of TI/PbO2 electrodes by a thermal-electrochemical method

    Directory of Open Access Journals (Sweden)

    Laurindo Edison A.

    2000-01-01

    Full Text Available Looking for electrodes with a high overpotential for the oxygen evolution reaction (OER, useful for the oxidation of organic pollutants, Ti/PbO2 electrodes were prepared by a thermal-electrochemical method and their performance was compared with that of electrodeposited electrodes. The open-circuit potential for these electrodes in 0.5 mol L-1 H2SO4 presented quite stable similar values. X-ray diffraction analyses showed the thermal-electrochemical oxide to be a mixture of ort-PbO, tetr-PbO and ort-PbO2. On the other hand, the electrodes obtained by electrodeposition were in the tetr-PbO2 form. Analyses by scanning electron microscopy showed that the basic morphology of the thermal-electrochemical PbO2 is determined in the thermal step, being quite distinct from that of the electrodeposited electrodes. Polarization curves in 0.5 mol L-1 H2SO4 showed that in the case of the thermal-electrochemical PbO2 electrodes the OER was shifted to more positive potentials. However, the values of the Tafel slopes, quite high, indicate that passivating films were possibly formed on the Ti substrates, which could eventually explain the somewhat low current values for OER.

  8. Electrochemical impedance spectroscopic characterization of titanium during alkali treatment and apatite growth in simulated body fluid

    International Nuclear Information System (INIS)

    Raman, V.; Tamilselvi, S.; Rajendran, N.

    2007-01-01

    Alkali treatment of titanium with subsequent heat treatment has been adapted as an important pre-treatment procedure for hydroxyapatite formation in orthopaedic applications. The electrochemical study during the alkali treatment process has not been explored yet. In the present work, electrochemical impedance spectroscopic (EIS) studies have been employed to analyse the electrochemical behaviour of titanium during the alkali treatment. The open circuit potential and potentiodynamic polarisation measurements were carried out in simulated body fluid (SBF) solution. Scanning electron microscopy and energy dispersive X-ray analysis were used to characterize the surface morphology and to correlate the results obtained from the electrochemical studies. An optimum growth of the passive film was found to occur at the end of 17th hour of treatment by alkali treatment. The alkali treated titanium immersed in SBF solution for various durations exhibited the formation of a duplex layer structure due to an inner barrier layer and an outer gel layer during the initial periods of immersion. However, with increase in immersion time to 10 days, a stable apatite layer was formed over the barrier layer and this was confirmed from the equivalent circuit fitted for the impedance data

  9. Electrochemical impedance spectroscopic characterization of titanium during alkali treatment and apatite growth in simulated body fluid

    Energy Technology Data Exchange (ETDEWEB)

    Raman, V.; Tamilselvi, S. [Department of Chemistry, MIT Campus, Anna University, Chennai 600 044 (India); Rajendran, N. [Department of Chemistry, MIT Campus, Anna University, Chennai 600 044 (India)], E-mail: nrajendran@annauniv.edu

    2007-09-30

    Alkali treatment of titanium with subsequent heat treatment has been adapted as an important pre-treatment procedure for hydroxyapatite formation in orthopaedic applications. The electrochemical study during the alkali treatment process has not been explored yet. In the present work, electrochemical impedance spectroscopic (EIS) studies have been employed to analyse the electrochemical behaviour of titanium during the alkali treatment. The open circuit potential and potentiodynamic polarisation measurements were carried out in simulated body fluid (SBF) solution. Scanning electron microscopy and energy dispersive X-ray analysis were used to characterize the surface morphology and to correlate the results obtained from the electrochemical studies. An optimum growth of the passive film was found to occur at the end of 17th hour of treatment by alkali treatment. The alkali treated titanium immersed in SBF solution for various durations exhibited the formation of a duplex layer structure due to an inner barrier layer and an outer gel layer during the initial periods of immersion. However, with increase in immersion time to 10 days, a stable apatite layer was formed over the barrier layer and this was confirmed from the equivalent circuit fitted for the impedance data.

  10. Contact microscopy with synchrotron radiation

    International Nuclear Information System (INIS)

    Panessa-Warren, B.J.

    1985-10-01

    Soft x-ray contact microscopy with synchrotron radiation offers the biologist and especially the microscopist, a way to morphologically study specimens that could not be imaged by conventional TEM, STEM or SEM methods (i.e. hydrated samples, samples easily damaged by an electron beam, electron dense samples, thick specimens, unstained low contrast specimens) at spatial resolutions approaching those of the TEM, with the additional possibility to obtain compositional (elemental) information about the sample as well. Although flash x-ray sources offer faster exposure times, synchrotron radiation provides a highly collimated, intense radiation that can be tuned to select specific discrete ranges of x-ray wavelengths or specific individual wavelengths which optimize imaging or microanalysis of a specific sample. This paper presents an overview of the applications of x-ray contact microscopy to biological research and some current research results using monochromatic synchrotron radiation to image biological samples. 24 refs., 10 figs

  11. QUANTITATIVE CONFOCAL LASER SCANNING MICROSCOPY

    Directory of Open Access Journals (Sweden)

    Merete Krog Raarup

    2011-05-01

    Full Text Available This paper discusses recent advances in confocal laser scanning microscopy (CLSM for imaging of 3D structure as well as quantitative characterization of biomolecular interactions and diffusion behaviour by means of one- and two-photon excitation. The use of CLSM for improved stereological length estimation in thick (up to 0.5 mm tissue is proposed. The techniques of FRET (Fluorescence Resonance Energy Transfer, FLIM (Fluorescence Lifetime Imaging Microscopy, FCS (Fluorescence Correlation Spectroscopy and FRAP (Fluorescence Recovery After Photobleaching are introduced and their applicability for quantitative imaging of biomolecular (co-localization and trafficking in live cells described. The advantage of two-photon versus one-photon excitation in relation to these techniques is discussed.

  12. Selective sensitivity in Kerr microscopy.

    Science.gov (United States)

    Soldatov, I V; Schäfer, R

    2017-07-01

    A new technique for contrast separation in wide-field magneto-optical Kerr microscopy is introduced. Utilizing the light from eight light emitting diodes, guided to the microscope by glass fibers and being switched synchronously with the camera exposure, domain images with orthogonal in-plane sensitivity can be displayed simultaneously at real-time, and images with pure in-plane or polar contrast can be obtained. The benefit of this new method of contrast separation is demonstrated for Permalloy films, a NdFeB sinter magnet, and a cobalt crystal. Moreover, the new technique is shown to strongly enhance the sensitivity of Kerr microscopy by eliminating parasitic contrast contributions occurring in conventional setups. A doubling of the in-plane domain contrast and a sensitivity to Kerr rotations as low as 0.6 mdeg is demonstrated.

  13. Selective sensitivity in Kerr microscopy

    Science.gov (United States)

    Soldatov, I. V.; Schäfer, R.

    2017-07-01

    A new technique for contrast separation in wide-field magneto-optical Kerr microscopy is introduced. Utilizing the light from eight light emitting diodes, guided to the microscope by glass fibers and being switched synchronously with the camera exposure, domain images with orthogonal in-plane sensitivity can be displayed simultaneously at real-time, and images with pure in-plane or polar contrast can be obtained. The benefit of this new method of contrast separation is demonstrated for Permalloy films, a NdFeB sinter magnet, and a cobalt crystal. Moreover, the new technique is shown to strongly enhance the sensitivity of Kerr microscopy by eliminating parasitic contrast contributions occurring in conventional setups. A doubling of the in-plane domain contrast and a sensitivity to Kerr rotations as low as 0.6 mdeg is demonstrated.

  14. Limits to magnetic resonance microscopy

    International Nuclear Information System (INIS)

    Glover, Paul; Mansfield, Peter

    2002-01-01

    The last quarter of the twentieth century saw the development of magnetic resonance imaging (MRI) grow from a laboratory demonstration to a multi-billion dollar worldwide industry. There is a clinical body scanner in almost every hospital of the developed nations. The field of magnetic resonance microscopy (MRM), after mostly being abandoned by researchers in the first decade of MRI, has become an established branch of the science. This paper reviews the development of MRM over the last decade with an emphasis on the current state of the art. The fundamental principles of imaging and signal detection are examined to determine the physical principles which limit the available resolution. The limits are discussed with reference to liquid, solid and gas phase microscopy. In each area, the novel approaches employed by researchers to push back the limits of resolution are discussed. Although the limits to resolution are well known, the developments and applications of MRM have not reached their limit. (author)

  15. High-resolution electron microscopy

    CERN Document Server

    Spence, John C H

    2013-01-01

    This new fourth edition of the standard text on atomic-resolution transmission electron microscopy (TEM) retains previous material on the fundamentals of electron optics and aberration correction, linear imaging theory (including wave aberrations to fifth order) with partial coherence, and multiple-scattering theory. Also preserved are updated earlier sections on practical methods, with detailed step-by-step accounts of the procedures needed to obtain the highest quality images of atoms and molecules using a modern TEM or STEM electron microscope. Applications sections have been updated - these include the semiconductor industry, superconductor research, solid state chemistry and nanoscience, and metallurgy, mineralogy, condensed matter physics, materials science and material on cryo-electron microscopy for structural biology. New or expanded sections have been added on electron holography, aberration correction, field-emission guns, imaging filters, super-resolution methods, Ptychography, Ronchigrams, tomogr...

  16. Chemical and Electrochemical Synthesis of Polypyrrole Using Carrageenan as a Dopant: Polypyrrole/Multi-Walled Carbon Nanotube Nanocomposites

    Directory of Open Access Journals (Sweden)

    Mostafizur Rahaman

    2018-06-01

    Full Text Available In this article, iota-carrageenan (IC and kappa-carrageenan (KC are used as dopants for the chemical and electrochemical synthesis of polypyrrole (PPy. The composites of chemically synthesized PPy with multi-walled carbon nanotubes (MWNTs were prepared using an in situ technique. Both the dialyzed and non-dialyzed IC and KC were used as dopants for electrochemical polymerization of pyrrole. Chemically synthesized PPy and PPy/MWNTs composites were studied by ultraviolet visible (UV-vis absorption spectra to investigate the effect of the concentration and the incorporation of MWNTs. In addition, the electrical, thermal, mechanical, and microscopic characterizations of these films were performed to examine the effect of the dopants and MWNTs on these properties, along with their surface morphology. The films of electrochemically polymerized PPy were characterized using UV-vis absorption spectra, scanning electron microscopy, and cyclic voltammetry (CV. The results were then compared with the chemical polymerized PPy.

  17. Fabrication of an electrically conductive mixed self-assembled monolayer and its application in an electrochemical immunosensor

    International Nuclear Information System (INIS)

    Lee, Jung Bae; Namgung, Miok; Lee, Sang-Baek; Oh, Se Young

    2008-01-01

    Oligophenylethynylene thiol containing carboxylic acid in the tail group as a conducting wire bioreceptor was synthesized, and then its electrical property was investigated from the measurement of scanning tunneling microscopy (STM). Mixed self-assembled monolayer (SAM) consisting of 4-(2-(4-acetylthio)phenyl)ethynyl) benzoic acid (APBA) and butanethiol was fabricated in order to improve the electrical conductivity owing to the molecular orientation. We have examined the molecular orientation and the electrochemical activity of mixed SAM via X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). Especially, the prepared mixed SAM used as a bioreceptor in electrochemical prostate specific antigen (PSA) immunosensor showed higher electrochemical activity than that of the other SAMs

  18. Structural and electrochemical properties of single crystalline MoV 2O8 nanowires for energy storage devices

    KAUST Repository

    Shahid, Muhammad

    2013-05-01

    We report the synthesis of MoV2O8 nanowires of high quality using spin coating followed by the thermal annealing process. Transmission electron microscopy (TEM) reveals the average diameter of synthesized nanowire about 100 nm, and average length ranges from 1 to 5 μm. The TEM analysis further confirms the <001> growth direction of MoV 2O8 nanowires. The electrochemical properties of synthesized nanowires using cyclic voltammetry show the specific capacitance 56 Fg-1 at the scan rate of 5 mV s-1 that remains 24 Fg -1 at 100 mV s-1. The electrochemical measurements suggest that the MoV2O8 nanowires can be used as a material for the future electrochemical capacitors (energy storage devices). © 2012 Published by Elsevier Inc. All rights reserved.

  19. Structural and electrochemical properties of single crystalline MoV 2O8 nanowires for energy storage devices

    KAUST Repository

    Shahid, Muhammad; Liu, Jingling; Ali, Zahid; Shakir, Imran; Warsi, Muhammad Farooq

    2013-01-01

    We report the synthesis of MoV2O8 nanowires of high quality using spin coating followed by the thermal annealing process. Transmission electron microscopy (TEM) reveals the average diameter of synthesized nanowire about 100 nm, and average length ranges from 1 to 5 μm. The TEM analysis further confirms the <001> growth direction of MoV 2O8 nanowires. The electrochemical properties of synthesized nanowires using cyclic voltammetry show the specific capacitance 56 Fg-1 at the scan rate of 5 mV s-1 that remains 24 Fg -1 at 100 mV s-1. The electrochemical measurements suggest that the MoV2O8 nanowires can be used as a material for the future electrochemical capacitors (energy storage devices). © 2012 Published by Elsevier Inc. All rights reserved.

  20. Electrochemical assisted photocatalytic degradation of salicylic acid with highly ordered TiO{sub 2} nanotube electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qian [The State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Zhu, Jinwei [China Aerospace Science and Technology Corporation Fourty-fourth Research Institution (China); Wang, Ying; Feng, Jiangtao [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Yan, Wei, E-mail: yanwei@mail.xjtu.edu.cn [The State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Xu, Hao, E-mail: xuhao@mail.xjtu.edu.cn [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China)

    2014-07-01

    To explore the kinetics of photoelectrocatalytic degradation of salicylic acid, one of the important PPCPs, highly ordered TiO{sub 2} nanotube arrays (NTs) were prepared by the electrochemical anodization and characterized with scanning electron microscopy and X-ray diffraction techniques. The effect of TiO{sub 2} NTs properties, bias potential, initial salicylic acid concentration and solution pH on the degradation efficiency was studied and carefully analyzed. The results revealed that the salicylic acid degradation follows quasi-first order kinetics in the photoelectrocatalytic process, and the fastest decay kinetics was achieved in acidic environment (pH 2). The result was further interpreted through the electrochemical impedance spectroscopy. It is confirmed that the electrochemical assisted photocatalysis is a synergetic approach to combat stable organic substances with improved efficiency.

  1. Influence of Monomer Concentration on the Morphologies and Electrochemical Properties of PEDOT, PANI, and PPy Prepared from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Shalini Kulandaivalu

    2016-01-01

    Full Text Available Poly(3,4-ethylenedioxyhiophene (PEDOT, polyaniline (PANI, and polypyrrole (PPy were prepared on indium tin oxide (ITO substrate via potentiostatic from aqueous solutions containing monomer and lithium perchlorate. The concentration of monomers was varied between 1 and 10 mM. The effects of monomer concentration on the polymers formation were investigated and compared by using Fourier transform infrared spectroscopy (FTIR, Raman spectroscopy, scanning electron microscopy (SEM, cyclic voltammetry (CV, and electrochemical impedance spectroscopy (EIS measurements. FTIR and Raman spectra showed no changes in the peaks upon the increment of the concentration. Based on the SEM images, the increment in monomer concentration gives significant effect on morphologies and eventually affects the electrochemical properties. PEDOT electrodeposited from 10 mM solution showed excellent electrochemical properties with the highest specific capacitance value of 12.8 mF/cm2.

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

    International Nuclear Information System (INIS)

    Zhou Wei; Aung, Naing Naing; Sun Yangshan

    2009-01-01

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

  3. An investigation of the electrochemical action of the epoxy zinc-rich coatings containing surface modified aluminum nanoparticle

    Science.gov (United States)

    Jalili, M.; Rostami, M.; Ramezanzadeh, B.

    2015-02-01

    Aluminum nanoparticle was modified with amino trimethylene phosphonic acid (ATMP). The surface characterization of the nanoparticles was done by X-ray photo electron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis. The influence of the replacement of 2 wt% of zinc dust in the standard zinc-rich epoxy coating by nanoparticles on the electrochemical action of the coating was studied by electrochemical impedance spectroscopy (EIS) and salt spray tests. The morphology and phase composition of the zinc rich paints were evaluated by X-ray diffraction (XRD) and filed-emission scanning electron microscopy (FE-SEM). Results showed that the ATMP molecules successfully adsorbed on the surface of Al nanoparticles. Results obtained from salt spray and electrochemical measurements revealed that the addition of surface modified nanoparticles to the zinc rich coating enhanced its galvanic action and corrosion protection properties.

  4. Electrochemical deposition of gold-platinum alloy nanoparticles on an indium tin oxide electrode and their electrocatalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Song Yan; Ma Yuting; Wang Yuan [Department of Chemistry, Soochow University, Suzhou, Jiangsu 215123 (China); Di Junwei, E-mail: djw@suda.edu.c [Department of Chemistry, Soochow University, Suzhou, Jiangsu 215123 (China); Tu Yifeng [Department of Chemistry, Soochow University, Suzhou, Jiangsu 215123 (China)

    2010-07-01

    Gold-platinum (Au-Pt) hybrid nanoparticles (Au-PtNPs) were successfully deposited on an indium tin oxide (ITO) surface using a direct electrochemical method. The resulting nanoparticles were characterized by scanning electron microscopy (SEM), UV-vis spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and electrochemical methods. It was found that the size of the Au-PtNPs depends on the number of electrodeposition cycles. Au-PtNPs obtained by 20 electrodeposition cycles had a cauliflower-shaped structure with an average diameter of about 60 nm. These Au-PtNPs exhibited alloy properties. Electrochemical measurements showed that the charge transfer resistivity was significantly decreased for the Au-PtNPs/ITO electrode. Additionally, the Au-PtNPs displayed an electrocatalytic activity for nitrite oxidation and oxygen reduction. The Au-PtNPs/ITO electrodes reported herein could possibly be used as electrocatalysts and sensors.

  5. Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pruna, R., E-mail: rpruna@el.ub.edu; Palacio, F.; López, M. [SIC, Departament d' Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain); Pérez, J. [Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, E-08028 Barcelona (Spain); Mir, M. [Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, E-08028 Barcelona (Spain); Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Monforte de Lemos 3-5 Pabellón 11, E-28029 Madrid (Spain); Blázquez, O.; Hernández, S.; Garrido, B. [MIND-IN" 2UB, Departament d' Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain)

    2016-08-08

    The electroactivity of nanostructured indium tin oxide (ITO) has been investigated for its further use in applications such as sensing biological compounds by the analysis of redox active molecules. ITO films were fabricated by using electron beam evaporation at different substrate temperatures and subsequently annealed for promoting their crystallization. The morphology of the deposited material was monitored by scanning electron microscopy, confirming the deposition of either thin films or nanowires, depending on the substrate temperature. Electrochemical surface characterization revealed a 45 % increase in the electroactive surface area of nanostructured ITO with respect to thin films, one third lower than the geometrical surface area variation determined by atomic force microscopy. ITO surfaces were functionalized with a model organic molecule known as 6-(ferrocenyl)hexanethiol. The chemical attachment was done by means of a glycidoxy compound containing a reactive epoxy group, the so-called 3-glycidoxypropyltrimethoxy-silane. ITO functionalization was useful for determining the benefits of nanostructuration on the surface coverage of active molecules. Compared to ITO thin films, an increase in the total peak height of 140 % was observed for as-deposited nanostructured electrodes, whereas the same measurement for annealed electrodes resulted in an increase of more than 400 %. These preliminary results demonstrate the ability of nanostructured ITO to increase the surface-to-volume ratio, conductivity and surface area functionalization, features that highly benefit the performance of biosensors.

  6. Basic electrochemical properties of sputtered gold film electrodes

    International Nuclear Information System (INIS)

    Libansky, Milan; Zima, Jiri; Barek, Jiri; Reznickova, Alena; Svorcik, Vaclav; Dejmkova, Hana

    2017-01-01

    Gold nanolayers made by sputtering of pure gold (physical vapour deposition) are commonly used for many biophysical and material applications. However, the use of sputtering method for fabrication of working electrodes for electroanalytical purposes is less common. This paper focuses on the testing and characterization of sputtered working roughened gold nanostructured film electrodes, which fall into category of upcoming desirable new generation of nanostructured gold working electrodes. Gold nanostructured films (80 nm thin) were sputtered onto 50 μm thin PTFE substrates with three different types of treatment: pristine, plasma treated, and plasma treated and subsequently spontaneously grafted with biphenyl-4,4′-dithiol. The characterization of gold nanostructured film electrodes was carried out by examination of the electrode reaction of standard redox probes (ferrocyanide/ferricyanide, hydroquinone/benzoquinone) in different types of supporting electrolytes (BR buffers of various pH, KCl, KNO 3 , H 2 SO 4 ), by exploration of the electrode surface by scanning electron microscopy, by atomic force microscopy accompanied by elementary analysis and contact angle measurements. The testing of electrodes was complemented by an attempt to calculate their real surface areas from Randles-Sevcik equation. All results were compared to conventional bulk gold electrode. The practical applicability of the nanostructured gold electrodes as sensors for the determination of environmental pollutants was verified by voltammetric determination of hydroquinone as a model electrochemically oxidisable organic environmental pollutant.

  7. Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces

    International Nuclear Information System (INIS)

    Pruna, R.; Palacio, F.; López, M.; Pérez, J.; Mir, M.; 2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (MIND-IN2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" >Blázquez, O.; 2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (MIND-IN2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" >Hernández, S.; 2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (MIND-IN2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" >Garrido, B.

    2016-01-01

    The electroactivity of nanostructured indium tin oxide (ITO) has been investigated for its further use in applications such as sensing biological compounds by the analysis of redox active molecules. ITO films were fabricated by using electron beam evaporation at different substrate temperatures and subsequently annealed for promoting their crystallization. The morphology of the deposited material was monitored by scanning electron microscopy, confirming the deposition of either thin films or nanowires, depending on the substrate temperature. Electrochemical surface characterization revealed a 45 % increase in the electroactive surface area of nanostructured ITO with respect to thin films, one third lower than the geometrical surface area variation determined by atomic force microscopy. ITO surfaces were functionalized with a model organic molecule known as 6-(ferrocenyl)hexanethiol. The chemical attachment was done by means of a glycidoxy compound containing a reactive epoxy group, the so-called 3-glycidoxypropyltrimethoxy-silane. ITO functionalization was useful for determining the benefits of nanostructuration on the surface coverage of active molecules. Compared to ITO thin films, an increase in the total peak height of 140 % was observed for as-deposited nanostructured electrodes, whereas the same measurement for annealed electrodes resulted in an increase of more than 400 %. These preliminary results demonstrate the ability of nanostructured ITO to increase the surface-to-volume ratio, conductivity and surface area functionalization, features that highly benefit the performance of biosensors.

  8. Computers in field ion microscopy

    International Nuclear Information System (INIS)

    Suvorov, A.L.; Razinkova, T.L.; Sokolov, A.G.

    1980-01-01

    A review is presented of computer applications in field ion microscopy (FIM). The following topics are discussed in detail: (1) modeling field ion images in perfect crystals, (2) a general scheme of modeling, (3) modeling of the process of field evaporation, (4) crystal structure defects, (5) alloys, and (6) automation of FIM experiments and computer-assisted processing of real images. 146 references are given

  9. CNNs for electron microscopy segmentation

    OpenAIRE

    García-Amorena García, Pablo

    2013-01-01

    In the framework of Biomedicine, mitochondria are known to play an important role in neural function. Recent studies show mitochondrial morphology to be crucial to cellular physiology and synaptic function, and a link between mitochondrial defects and neuro-degenerative diseases is strongly suspected. Electron microscopy (EM), with its very high resolution in all three directions, is one of the key tools to look more closely into these tissues, but the huge amounts of data it produces m...

  10. Probing the electrochemical behaviour of SWCNT-cobalt nanoparticles and their electrocatalytic activities towards the detection of nitrite at acidic and physiological pH conditions

    CSIR Research Space (South Africa)

    Adekunle, AS

    2010-05-01

    Full Text Available was confirmed by field emission scanning electron microscopy (FESEM), AFM and EDX techniques. The electron transfer behavior of the modified electrodes was investigated in [Fe (CN)6]3-/4- redox probe using cyclic voltammetry (CV) and electrochemical impedance...

  11. Electrochemical Sensors Based on Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Md. Aminur Rahman

    2009-03-01

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

  12. Electrochemical, Chemical and Enzymatic Oxidations of Phenothiazines

    NARCIS (Netherlands)

    Blankert, B.; Hayen, H.; van Leeuwen, S.M.; Karst, U.; Bodoki, E.; Lotrean, S.; Sandulescu, R.; Mora Diaz, N.; Dominguez, O.; Arcos, J.; Kauffmann, J.-M.

    2005-01-01

    The oxidation of several phenothiazine drugs (phenothiazine, promethazine hydrochloride, promazine hydrochloride, trimeprazine hydrochloride and ethopropazine hydrochloride) has been carried out in aqueous acidic media by electrochemical, chemical and enzymatic methods. The chemical oxidation was

  13. Significant improvement of electrochemical performance of Cu ...

    Indian Academy of Sciences (India)

    LiVPO4F cathode material for lithium-ion batteries. YU ZHANGa,∗, XIAOLAN BAIb ... and energy dispersive spectroscopy (EDS). ... Analysis of electrochemical impedance spectra (EIS) ... studied with a SEM (JSM-7500F, Japan) equipped with.

  14. High temperature and pressure electrochemical test station

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Allebrod, Frank; Mogensen, Mogens Bjerg

    2013-01-01

    An electrochemical test station capable of operating at pressures up to 100 bars and temperatures up to 400 ◦C has been established. It enables control of the partial pressures and mass flow of O2, N2, H2, CO2, and H2O in a single or dual environment arrangement, measurements with highly corrosive...... media, as well as localized sampling of gas evolved at the electrodes for gas analysis. A number of safety and engineering design challenges have been addressed. Furthermore, we present a series of electrochemical cell holders that have been constructed in order to accommodate different types of cells...... and facilitate different types of electrochemical measurements. Selected examples of materials and electrochemical cells examined in the test station are provided, ranging from the evaluation of the ionic conductivity of liquid electrolytic solutions immobilized in mesoporous ceramic structures...

  15. Electrochemical Impedance Studies of SOFC Cathodes

    DEFF Research Database (Denmark)

    Hjelm, Johan; Søgaard, Martin; Wandel, Marie

    2007-01-01

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

  16. Electrochemical properties of ion implanted silicon

    International Nuclear Information System (INIS)

    Pham minh Tan.

    1979-11-01

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

  17. Electrochemical conversion of micropollutants in gray water

    NARCIS (Netherlands)

    Butkovskyi, A.; Jeremiasse, A.W.; Hernandez Leal, L.; Zande, van der T.; Rijnaarts, H.; Zeeman, G.

    2014-01-01

    Electrochemical conversion of micropollutants in real gray water effluent was studied for the first time. Six compounds that are frequently found in personal care and household products, namely methylparaben, propylparaben, bisphenol A, triclosan, galaxolide, and 4- methylbenzilidene camphor

  18. Electrochemical remediation technologies for soil and groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Doering, F. [Electrochemical Processes I.I. c. Valley Forge, PA (United States)]|[P2 Soil Remediation, Inc. Stuttgart (Germany); Doering, N. [P2 Soil Remediation, Inc. Stuttgart (Germany)

    2001-07-01

    In Direct Current Technologies (DCTs) a direct current electricity is passed between at least two subsurface electrodes in order to effect the remediation of the groundwater and/or the soil. DCTs in line with the U.S.-terminology comprise of the ElectroChemical Remediation Technologies (ECRTs), and GeoKinetics. The primary distinction between ECRTs and ElectroKinetics are the power input, and the mode of operation, which are electrochemical reactions vs. mass transport. ECRTs combine phenomena of colloid (surface) electrochemistry with the phenomena of Induced Polarization (IP). This report focuses on ECRTs, comprising of the ElectroChemical GeoOxidation (ECGO) for the mineralization of organic pollutants to finally carbon dioxide and water, and Induced Complexation (IC), related to the electrochemical conversion of metals enhancing the mobilization and precipitation of heavy metals on both electrodes. Both technologies are based on reduction-oxidation (redox) reactions at the scale of the individual soil particles. (orig.)

  19. Applications of Nonlinear Electrochemical Impedance Spectroscopy (NLEIS)

    KAUST Repository

    Adler, S. B.

    2013-01-01

    This paper reviews the use of nonlinear electrochemical impedance spectroscopy (NLEIS) in the analysis of SOFC electrode reactions. By combining EIS and NLEIS, as well as other independent information about an electrode material, it becomes possible

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

    African Journals Online (AJOL)

    2011-12-31

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