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Sample records for electrochemical microscopy rc-secm

  1. Electrochemical force microscopy

    DOEpatents

    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.

  2. Scanning Electrochemical Microscopy in Neuroscience

    NASA Astrophysics Data System (ADS)

    Schulte, Albert; Nebel, Michaela; Schuhmann, Wolfgang

    2010-07-01

    This article reviews recent work involving the application of scanning electrochemical microscopy (SECM) to the study of individual cultured living cells, with an emphasis on topographical and functional imaging of neuronal and secretory cells of the nervous and endocrine system. The basic principles of biological SECM and associated negative amperometric-feedback and generator/collector-mode SECM imaging are discussed, and successful use of the methodology for screening soft and fragile membranous objects is outlined. The drawbacks of the constant-height mode of probe movement and the benefits of the constant-distance mode of SECM operation are described. Finally, representative examples of constant-height and constant-distance mode SECM on a variety of live cells are highlighted to demonstrate the current status of single-cell SECM in general and of SECM in neuroscience in particular.

  3. Kelvin Probe Force Microscopy in liquid using Electrochemical Force Microscopy

    DOE PAGES

    Collins, Liam; Jesse, Stephen; Kilpatrick, J.; ...

    2015-01-01

    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 watermore » 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.« less

  4. Kelvin Probe Force Microscopy in liquid using Electrochemical Force Microscopy

    SciTech Connect

    Collins, Liam; Jesse, Stephen; Kilpatrick, J.; Tselev, Alexander; Okatan, Mahmut Baris; Kalinin, Sergei V.; Rodriguez, Brian

    2015-01-01

    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.

  5. Visualization of ion transport in Nafion using electrochemical strain microscopy

    SciTech Connect

    Kim, Suran; No, Kwangsoo; Hong, Seungbum

    2015-12-24

    The electromechanical response of a Nafion membrane immersed in water was probed using electrochemical strain microscopy (ESM) to redistribute protons and measure the resulting local strain that is caused by the movement of protons. We also measured the relaxation of protons from the surface resulting from proton diffusion. Using this technique, we can visualize and analyze the local strain change resulting from the redistribution and relaxation of hydrated protons.

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

    PubMed

    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.

  7. Scanning electrochemical microscopy of Li-ion batteries.

    PubMed

    Ventosa, E; Schuhmann, W

    2015-11-21

    Li-ion batteries (LIBs) are receiving increasing attention over the past decade due to their high energy density. This energy storage technology is expected to continue improving the performance, especially for its large-scale deployment in plug-in hybrid electric vehicles (PHEVs) and full electric vehicles (EVs). Such improvement requires having a large variety of analytical techniques at scientists' disposal in order to understand and address the multiple mechanisms and processes occurring simultaneously in this complex system. This perspective article aims to highlight the strength and potential of scanning electrochemical microscopy (SECM) in this field. After a brief description of a LIB system and the most commonly used techniques in this field, the unique information provided by SECM is illustrated by discussing several recent examples from the literature.

  8. Microfluidic push-pull probe for scanning electrochemical microscopy.

    PubMed

    Momotenko, Dmitry; Cortes-Salazar, Fernando; Lesch, Andreas; Wittstock, Gunther; Girault, Hubert H

    2011-07-01

    This paper presents a microfluidic push-pull probe for scanning electrochemical microscopy (SECM) consisting of a working microelectrode, an integrated counter/reference electrode and two microchannels for pushing and pulling an electrolyte solution to and away from a substrate. With such a configuration, a droplet of a permanently renewed redox mediator solution is maintained just at the probe tip to carry out SECM measurements on initially dry substrates or in microenvironments. For SECM imaging purposes, the probe fabricated in a soft polymer material is used in a contact regime. SECM images of various gold-on-glass samples demonstrate the proof-of-concept of a push-pull probe for local surface activity characterization with high spatial resolution even on vertically oriented substrates. Finite element computations were performed to guide the improvement of the probe sensitivity.

  9. Scanning Electrochemical Microscopy of DNA Monolayers Modified with Nile Blue

    PubMed Central

    Gorodetsky, Alon A.; Hammond, William J.; Hill, Michael G.; Slowinski, Krzysztof; Barton, Jacqueline K.

    2009-01-01

    Scanning electrochemical microscopy (SECM) is used to probe long-range charge transport (CT) through DNA monolayers containing the redox-active Nile Blue (NB) intercalator covalently affixed at a specific location in the DNA film. At substrate potentials negative of the formal potential of covalently attached NB, the electrocatalytic reduction of Fe(CN)63− generated at the SECM tip is observed only when NB is located at the DNA/solution interface; for DNA films containing NB in close proximity to the DNA/electrode interface, the electrocatalytic effect is absent. This behavior is consistent with both rapid DNA-mediated CT between the NB intercalator and the gold electrode as well as a rate-limiting electron transfer between NB and the solution phase Fe(CN)63−. The DNA-mediated nature of the catalytic cycle is confirmed through sequence-specific and localized detection of attomoles of TATA-binding protein, a transcription factor that severely distorts DNA upon binding. Importantly, the strategy outlined here is general and allows for the local investigation of the surface characteristics of DNA monolayers both in the absence and in the presence of DNA binding proteins. These experiments highlight the utility of DNA-modified electrodes as versatile platforms for SECM detection schemes that take advantage of CT mediated by the DNA base pair stack. PMID:19053641

  10. In Situ Electrochemical Transmission Electron Microscopy for Battery Research

    SciTech Connect

    Mehdi, Beata L.; Gu, Meng; Parent, Lucas R.; Xu, Wu; Nasybulin, Eduard N.; Chen, Xilin; Unocic, Raymond R.; Xu, Pinghong; Welch, David A.; Abellan, Patricia; Zhang, Jiguang; Liu, Jun; Wang, Chong M.; Arslan, Ilke; Evans, James E.; Browning, Nigel D.

    2014-04-01

    The recent development of in situ liquid stages for (scanning) transmission electron microscopes now makes it possible for us to study the details of electrochemical processes under operando conditions. As electrochemical processes are complex, care must be taken to calibrate the system before any in situ/operando observations. In addition, as the electron beam can cause effects that look similar to electrochemical processes at the electrolyte/electrode interface, an understanding of the role of the electron beam in modifying the operando observations must also be understood. In this paper we describe the design, assembly, and operation of an in situ electrochemical cell, paying particular attention to the method for controlling and quantifying the experimental parameters. The use of this system is then demonstrated for the lithiation/delithiation of silicon nanowires.

  11. In-situ electrochemical transmission electron microscopy for battery research.

    PubMed

    Mehdi, B Layla; Gu, Meng; Parent, Lucas R; Xu, Wu; Nasybulin, Eduard N; Chen, Xilin; Unocic, Raymond R; Xu, Pinghong; Welch, David A; Abellan, Patricia; Zhang, Ji-Guang; Liu, Jun; Wang, Chong-Min; Arslan, Ilke; Evans, James; Browning, Nigel D

    2014-04-01

    The recent development of in-situ liquid stages for (scanning) transmission electron microscopes now makes it possible for us to study the details of electrochemical processes under operando conditions. As electrochemical processes are complex, care must be taken to calibrate the system before any in-situ/operando observations. In addition, as the electron beam can cause effects that look similar to electrochemical processes at the electrolyte/electrode interface, an understanding of the role of the electron beam in modifying the operando observations must also be understood. In this paper we describe the design, assembly, and operation of an in-situ electrochemical cell, paying particular attention to the method for controlling and quantifying the experimental parameters. The use of this system is then demonstrated for the lithiation/delithiation of silicon nanowires.

  12. Pointed carbon fiber ultramicroelectrodes: a new probe option for electrochemical scanning tunneling microscopy.

    PubMed

    Sripirom, Jiyapa; Kuhn, Sonja; Jung, Ulrich; Magnussen, Olaf; Schulte, Albert

    2013-01-15

    Carbon tips for in situ scanning tunneling microscopy studies in an electrochemical environment were prepared by electrochemical etching of carbon fibers and subsequent coating with electrodeposition paint and a silicone elastomer. The tips obtained were stable in acidic electrolyte and allowed high-resolution in situ imaging of the bare Au(111) electrode surface and of Au(111) covered by monolayers of the octyl-triazatriangulenium molecule.

  13. Electro-deposition of Cu studied with in situ electrochemical scanning transmission x-ray microscopy

    NASA Astrophysics Data System (ADS)

    Hitchcock, A. P.; Qin, Z.; Rosendahl, S. M.; Lee, V.; Reynolds, M.; Hosseinkhannazer, H.

    2016-01-01

    Soft X-ray scanning transmission X-ray microscopy (STXM) was used to investigate Cu deposition onto, and stripping from a Au surface. Cu 2p spectromicroscopy was used to analyze initial and final states (ex situ processing) and follow the processes in situ. The in situ experiments were carried out using a static electrochemical cell with an electrolyte layer thickness of ˜1 μm. A new apparatus for in situ electrochemical STXM is described.

  14. High-resolution friction force microscopy under electrochemical control

    NASA Astrophysics Data System (ADS)

    Labuda, Aleksander; Paul, William; Pietrobon, Brendan; Lennox, R. Bruce; Grütter, Peter H.; Bennewitz, Roland

    2010-08-01

    We report the design and development of a friction force microscope for high-resolution studies in electrochemical environments. The design choices are motivated by the experimental requirements of atomic-scale friction measurements in liquids. The noise of the system is analyzed based on a methodology for the quantification of all the noise sources. The quantitative contribution of each noise source is analyzed in a series of lateral force measurements. Normal force detection is demonstrated in a study of the solvation potential in a confined liquid, octamethylcyclotetrasiloxane. The limitations of the timing resolution of the instrument are discussed in the context of an atomic stick-slip measurement. The instrument is capable of studying the atomic friction contrast between a bare Au(111) surface and a copper monolayer deposited at underpotential conditions in perchloric acid.

  15. Electrochemical reactions in subfemtoliter-droplets studied with plasmonics-based electrochemical current microscopy.

    PubMed

    Wang, Yixian; Shan, Xiaonan; Cui, Fengjuan; Li, Jinghong; Wang, Shaopeng; Tao, Nongjian

    2015-01-06

    We report on a plasmonics-based electrochemical current imaging of redox reactions in aqueous droplets with diameters varying from a few hundred nanometers (tens of attoliter in volume) to a few micrometers. The imaging technique allows us to obtain cyclic voltammograms of multiple droplets on a gold electrode simultaneously and to examine the local redox reactions within a droplet. The results are supported by numerical simulations. The work demonstrates a new capability of studying electrochemistry in microdroplets, which offers an opportunity to understand electrochemical reactions within a small confined volume.

  16. Reactivity of monolayer chemical vapor deposited graphene imperfections studied using scanning electrochemical microscopy.

    PubMed

    Tan, Cen; Rodríguez-López, Joaquín; Parks, Joshua J; Ritzert, Nicole L; Ralph, Daniel C; Abruña, Héctor D

    2012-04-24

    Imperfections that disrupt the sp(2) conjugation of graphene can alter its electrical, chemical, and mechanical properties. Here we report on the examination of monolayer chemical vapor deposited graphene imperfections using scanning electrochemical microscopy in the feedback mode. It was found that the sites with a large concentration of defects are approximately 1 order of magnitude more reactive, compared to more pristine graphene surfaces, toward electrochemical reactions. Furthermore, we successfully passivated the activity of graphene defects by carefully controlling the electropolymerization conditions of o-phenylenediamine. With further electropolymerization, a thin film of the polymer was formed, and it was found to be insulating in nature toward heterogeneous electron transfer processes. The use of spatially resolved scanning electrochemical microscopy for detecting the presence and the "healing" of defects on graphene provides a strategy for in situ characterization and control of this attractive surface, enabling optimization of its properties for application in electronics, sensing, and electrocatalysis.

  17. Mapping Ionic Currents and Reactivity on the Nanoscale: Electrochemical Strain Microscopy

    SciTech Connect

    Kalinin, S.V.

    2010-10-19

    Solid-state electrochemical processes in oxides underpin a broad spectrum of energy and information storage devices, ranging from Li-ion and Li-air batteries, to solid oxide fuel cells (SOFC) to electroresistive and memristive systems. These functionalities are controlled by the bias-driven diffusive and electromigration transport of mobile ionic species, as well as intricate a set of electrochemical and defect-controlled reactions at interfaces and in bulk. Despite the wealth of device-level and atomistic studies, little is known on the mesoscopic mechanisms of ion diffusion and electronic transport on the level of grain clusters, individual grains, and extended defects. The development of the capability for probing ion transport on the nanometer scale is a key to deciphering complex interplay between structure, functionality, and performance in these systems. Here we introduce Electrochemical Strain Microscopy, a scanning probe microscopy technique based on strong strain-bias coupling in the systems in which local ion concentrations are changed by electrical fields. The imaging capability, as well as time- and voltage spectroscopies analogous to traditional current based electrochemical characterization methods are developed. The reversible intercalation of Li and mapping electrochemical activity in LiCoO2 is demonstrated, illustrating higher Li diffusivity at non-basal planes and grain boundaries. In Si-anode device structure, the direct mapping of Li diffusion at extended defects and evolution of Li-activity with charge state is explored. The electrical field-dependence of Li mobility is studied to determine the critical bias required for the onset of electrochemical transformation, allowing reaction and diffusion processes in the battery system to be separated at each location. Finally, the applicability of ESM for probing oxygen vacancy diffusion and oxygen reduction/evolution reactions is illustrated, and the high resolution ESM maps are correlated with

  18. Electrochemical push-pull probe: from scanning electrochemical microscopy to multimodal altering of cell microenvironment.

    PubMed

    Bondarenko, Alexandra; Cortés-Salazar, Fernando; Gheorghiu, Mihaela; Gáspár, Szilveszter; Momotenko, Dmitry; Stanica, Luciana; Lesch, Andreas; Gheorghiu, Eugen; Girault, Hubert H

    2015-04-21

    To understand biological processes at the cellular level, a general approach is to alter the cells' environment and to study their chemical responses. Herein, we present the implementation of an electrochemical push-pull probe, which combines a microfluidic system with a microelectrode, as a tool for locally altering the microenvironment of few adherent living cells by working in two different perturbation modes, namely electrochemical (i.e., electrochemical generation of a chemical effector compound) and microfluidic (i.e., infusion of a chemical effector compound from the pushing microchannel, while simultaneously aspirating it through the pulling channel, thereby focusing the flow between the channels). The effect of several parameters such as flow rate, working distance, and probe inclination angle on the affected area of adherently growing cells was investigated both theoretically and experimentally. As a proof of concept, localized fluorescent labeling and pH changes were purposely introduced to validate the probe as a tool for studying adherent cancer cells through the control over the chemical composition of the extracellular space with high spatiotemporal resolution. A very good agreement between experimental and simulated results showed that the electrochemical perturbation mode enables to affect precisely only a few living cells localized in a high-density cell culture.

  19. Electrochemical scanning tunneling microscopy and spectroscopy for single-molecule investigation.

    PubMed

    Alessandrini, Andrea; Facci, Paolo

    2013-01-01

    The technique of electrochemical scanning tunneling microscopy (ECSTM) and spectroscopy (ECSTS) for studying electron transport through single redox molecules is here described. Redox molecules of both biological and organic nature have been studied by this technique with the aim of understanding the transport mechanisms ruling the flow of electrons via a single molecule placed in a nanometer-sized gap between two electrodes while elucidating the role of the redox density of states brought about by the molecule. The obtained results provide unique clues to single-molecule transport behavior and support the concept of single-molecule electrochemical gating.

  20. Atomic force microscopy with nanoelectrode tips for high resolution electrochemical, nanoadhesion and nanoelectrical imaging

    NASA Astrophysics Data System (ADS)

    Nellist, Michael R.; Chen, Yikai; Mark, Andreas; Gödrich, Sebastian; Stelling, Christian; Jiang, Jingjing; Poddar, Rakesh; Li, Chunzeng; Kumar, Ravi; Papastavrou, Georg; Retsch, Markus; Brunschwig, Bruce S.; Huang, Zhuangqun; Xiang, Chengxiang; Boettcher, Shannon W.

    2017-03-01

    Multimodal nano-imaging in electrochemical environments is important across many areas of science and technology. Here, scanning electrochemical microscopy (SECM) using an atomic force microscope (AFM) platform with a nanoelectrode probe is reported. In combination with PeakForce tapping AFM mode, the simultaneous characterization of surface topography, quantitative nanomechanics, nanoelectronic properties, and electrochemical activity is demonstrated. The nanoelectrode probe is coated with dielectric materials and has an exposed conical Pt tip apex of ∼200 nm in height and of ∼25 nm in end-tip radius. These characteristic dimensions permit sub-100 nm spatial resolution for electrochemical imaging. With this nanoelectrode probe we have extended AFM-based nanoelectrical measurements to liquid environments. Experimental data and numerical simulations are used to understand the response of the nanoelectrode probe. With PeakForce SECM, we successfully characterized a surface defect on a highly-oriented pyrolytic graphite electrode showing correlated topographical, electrochemical and nanomechanical information at the highest AFM-SECM resolution. The SECM nanoelectrode also enabled the measurement of heterogeneous electrical conductivity of electrode surfaces in liquid. These studies extend the basic understanding of heterogeneity on graphite/graphene surfaces for electrochemical applications.

  1. Atomic force microscopy with nanoelectrode tips for high resolution electrochemical, nanoadhesion and nanoelectrical imaging.

    PubMed

    Nellist, Michael R; Chen, Yikai; Mark, Andreas; Gödrich, Sebastian; Stelling, Christian; Jiang, Jingjing; Poddar, Rakesh; Li, Chunzeng; Kumar, Ravi; Papastavrou, Georg; Retsch, Markus; Brunschwig, Bruce S; Huang, Zhuangqun; Xiang, Chengxiang; Boettcher, Shannon W

    2017-03-03

    Multimodal nano-imaging in electrochemical environments is important across many areas of science and technology. Here, scanning electrochemical microscopy (SECM) using an atomic force microscope (AFM) platform with a nanoelectrode probe is reported. In combination with PeakForce tapping AFM mode, the simultaneous characterization of surface topography, quantitative nanomechanics, nanoelectronic properties, and electrochemical activity is demonstrated. The nanoelectrode probe is coated with dielectric materials and has an exposed conical Pt tip apex of ∼200 nm in height and of ∼25 nm in end-tip radius. These characteristic dimensions permit sub-100 nm spatial resolution for electrochemical imaging. With this nanoelectrode probe we have extended AFM-based nanoelectrical measurements to liquid environments. Experimental data and numerical simulations are used to understand the response of the nanoelectrode probe. With PeakForce SECM, we successfully characterized a surface defect on a highly-oriented pyrolytic graphite electrode showing correlated topographical, electrochemical and nanomechanical information at the highest AFM-SECM resolution. The SECM nanoelectrode also enabled the measurement of heterogeneous electrical conductivity of electrode surfaces in liquid. These studies extend the basic understanding of heterogeneity on graphite/graphene surfaces for electrochemical applications.

  2. Characterization of LiMn2O4 cathodes by electrochemical strain microscopy

    DOE PAGES

    Alikin, D. O.; Ievlev, A. V.; Luchkin, S. Yu.; ...

    2016-03-15

    Electrochemical strain microscopy (ESM) is a scanning probe microscopy(SPM) method in which the local electrodiffusion is probed via application of AC voltage to the SPM tip and registration of resulting electrochemical strain. In this study, we implemented ESM to measure local strain in bulk LiMn2O4 cathodes of a commercial Li-battery in different states of charge to investigate distribution of Li-ion mobility and concentration. Ramped AC ESM imaging and voltage spectroscopy were used to find the most reliable regime of measurements allowing separating and diminishing different contributions to ESM. This is not a trivial task due to complex geometry of themore » sample and various obstacles resulting in less predictable contributions of different origins into ESM response: electrostatic tip–surface interactions, charge injection, electrostriction, and flexoelectricity. Finally, understanding and control of these contributions is an important step towards quantitative interpretation of ESM data.« less

  3. Novel Automatic Electrochemical-mechanical Polishing (ECMP) of Metals for Scanning Electron Microscopy (Postprint)

    DTIC Science & Technology

    2010-03-23

    Micron 41 (2010) 615–621 619 Fig. 4 . XPS binding energy (eV) versus sputtering time (s) results for the Ti 2p peaks for the titanium samples: (a...improved the IQ values. 4 . Conclusions The electrochemical–mechanical polishing system (ECMP) removed material from titanium and nickel alloys at a...March 2014 4 . TITLE AND SUBTITLE NOVEL AUTOMATIC ELECTROCHEMICAL-MECHANICAL POLISHING (ECMP) OF METALS FOR SCANNING ELECTRON MICROSCOPY

  4. Monitoring charge storage processes in nanoscale oxides using electrochemical scanning probe microscopy.

    SciTech Connect

    Zavadil, Kevin Robert; Lu, Ping; Huang, Jian Yu

    2010-11-01

    Advances in electrochemical energy storage science require the development of new or the refinement of existing in situ probes that can be used to establish structure - activity relationships for technologically relevant materials. The drive to develop reversible, high capacity electrodes from nanoscale building blocks creates an additional requirement for high spatial resolution probes to yield information of local structural, compositional, and electronic property changes as a function of the storage state of a material. In this paper, we describe a method for deconstructing a lithium ion battery positive electrode into its basic constituents of ion insertion host particles and a carbon current collector. This model system is then probed in an electrochemical environment using a combination of atomic force microscopy and tunneling spectroscopy to correlate local activity with morphological and electronic configurational changes. Cubic spinel Li{sub 1+x}Mn{sub 2-x}O{sub 4} nanoparticles are grown on graphite surfaces using vacuum deposition methods. The structure and composition of these particles are determined using transmission electron microscopy and Auger microprobe analysis. The response of these particles to initial de-lithiation, along with subsequent electrochemical cycling, is tracked using scanning probe microscopy techniques in polar aprotic electrolytes (lithium hexafluorophosphate in ethylene carbonate:diethylcarbonate). The relationship between nanoparticle size and reversible ion insertion activity will be a specific focus of this paper.

  5. Electrochemical characterization of sub-micro-gram amounts of organic semiconductors using scanning droplet cell microscopy.

    PubMed

    Gasiorowski, Jacek; Mardare, Andrei I; Sariciftci, Niyazi S; Hassel, Achim Walter

    2013-02-15

    Scanning droplet cell microscopy (SDCM) uses a very small electrolyte droplet at the tip of a capillary which comes in contact with the working electrode. This method is particularly interesting for studies on organic semiconductors since it provides localized electrochemical investigations with high reproducibility. One clear advantage of applying SDCM is represented by the very small amounts of material necessary (less than 1 mg). Organic materials can be investigated quickly and inexpensively in electrochemical studies with a high throughput. In the present study, thin layers of poly(3-hexylthiophene) (P3HT), which is one of the most often used material for organic solar cells, were deposited on ITO/glass as working electrodes in SDCM studies. The redox reactions in 0.1 M tetra(n-butyl)ammonium hexafluorophosphate (TBAPF6) dissolved in propylene carbonate were studied by cyclic voltammetry and by electrochemical impedance spectroscopy. Two reversible, distinct oxidation steps of the P3HT were detected and their kinetics were studied in detail. The doping of P3HT increased due to the electrochemical oxidation and had resulted in a decrease of the film resistance by a few orders of magnitude. Due to localization on the sample various parameter combinations can be studied quantitatively and reproducibly.

  6. Mapping fluxes of radicals from the combination of electrochemical activation and optical microscopy.

    PubMed

    Munteanu, Sorin; Roger, Jean Paul; Fedala, Yasmina; Amiot, Fabien; Combellas, Catherine; Tessier, Gilles; Kanoufi, Frédéric

    2013-01-01

    The coating of gold (Au) electrode surfaces with nitrophenyl (NP) layers is studied by combination of electrochemical actuation and optical detection. The electrochemical actuation of the reduction of the nitrobenzenediazonium (NBD) precursor is used to generate NP radicals and therefore initiate the electrografting. The electrografting process is followed in situ and in real time by light reflectivity microscopy imaging, allowing for spatio-temporal imaging with sub-micrometer lateral resolution and sub-nanometer thickness sensitivity of the local growth of a transparent organic coating onto a reflecting Au electrode. The interest of the electrochemical actuation resides in its ability to finely control the grafting rate of the NP layer through the electrode potential. Coupling the electrochemical actuation with microscopic imaging of the electrode surface allows quantitative estimates of the local grafting rates and subsequently a real time and in situ mapping of the reacting fluxes of NP radicals on the surface. Over the 2 orders of magnitude range of grafting rates (from 0.04 to 4 nm s(-1)), it is demonstrated that the edge of Au electrodes are grafted -1.3 times more quickly than their centre, illustrating the manifestation of edge-effects on flux distribution at an electrode. A model is proposed to explain the observed edge-effect, it relies on the short lifetime of the intermediate NP radical species.

  7. Imaging of Biological Macromolecules on Mica in Humid Air by Scanning Electrochemical Microscopy

    NASA Astrophysics Data System (ADS)

    Fan, Fu-Ren F.; Bard, Allen J.

    1999-12-01

    Imaging of DNA, keyhole limpet hemocyanin, mouse monoclonal IgG, and glucose oxidase on a mica substrate has been accomplished by scanning electrochemical microscopy with a tungsten tip. The technique requires the use of a high relative humidity to form a thin film of water on the mica surface that allows electrochemical reactions to take place at the tip and produce a faradaic current (≈ 1\\ pA) that can be used to control tip position. The effect of relative humidity and surface pretreatment with buffer solutions on the ionic conductivity of a mica surface was investigated to find appropriate conditions for imaging. Resolution of the order of 1 nm was obtained.

  8. Importance and Challenges of Electrochemical in Situ Liquid Cell Electron Microscopy for Energy Conversion Research.

    PubMed

    Hodnik, Nejc; Dehm, Gerhard; Mayrhofer, Karl J J

    2016-09-20

    The foreseeable worldwide energy and environmental challenges demand renewable alternative sources, energy conversion, and storage technologies. Therefore, electrochemical energy conversion devices like fuel cells, electrolyzes, and supercapacitors along with photoelectrochemical devices and batteries have high potential to become increasingly important in the near future. Catalytic performance in electrochemical energy conversion results from the tailored properties of complex nanometer-sized metal and metal oxide particles, as well as support nanostructures. Exposed facets, surface defects, and other structural and compositional features of the catalyst nanoparticles affect the electrocatalytic performance to varying degrees. The characterization of the nanometer-size and atomic regime of electrocatalysts and its evolution over time are therefore paramount for an improved understanding and significant optimization of such important technologies like electrolyzers or fuel cells. Transmission electron microscopy (TEM) and scanning transmission electron microscope (STEM) are to a great extent nondestructive characterization tools that provide structural, morphological, and compositional information with nanoscale or even atomic resolution. Due to recent marked advancement in electron microscopy equipment such as aberration corrections and monochromators, such insightful information is now accessible in many institutions around the world and provides huge benefit to everyone using electron microscopy characterization in general. Classical ex situ TEM characterization of random catalyst locations however suffers from two limitations regarding catalysis. First, the necessary low operation pressures in the range of 10(-6) to 10(-9) mbar for TEM are not in line with typical reaction conditions, especially considering electrocatalytic solid-liquid interfaces, so that the active state cannot be assessed. Second, and somewhat related, is the lack of time resolution for the

  9. Second harmonic detection in the electrochemical strain microscopy of Ag-ion conducting glass

    SciTech Connect

    Yang, Sangmo; Okatan, Mahmut Baris; Paranthaman, Mariappan Parans; Jesse, Stephen; Noh, Tae Won; Kalinin, Sergei V.

    2014-11-14

    The first and second harmonic electromechanical responses and their cross-correlation in Ag-ion conducting glass were investigated using band-excitation electrochemical strain microscopy (ESM). Consecutive ESM images with increasing magnitudes of the applied AC voltage allowed observation of not only reversible surface displacement but also irreversible silver nanoparticle formation above a certain threshold voltage. The second harmonic ESM response was anticorrelated with the first harmonic response in many local regions. Furthermore, the nucleation sites of silver nanoparticles were closely related to the anti-correlated regions, specifically, with low second harmonic and high first harmonic ESM responses. The possible origins of the second harmonic ESM response are discussed.

  10. Convective heat transfer in a measurement cell for scanning electrochemical microscopy.

    PubMed

    Novev, Javor K; Compton, Richard G

    2016-11-21

    Electrochemical experiments, especially those performed with scanning electrochemical microscopy (SECM), are often carried out without taking special care to thermostat the solution; it is usually assumed that its temperature is homogeneous and equal to the ambient. The present study aims to test this assumption via numerical simulations of the heat transfer in a particular system - the typical measurement cell for SECM. It is assumed that the temperature of the solution is initially homogeneous but different from that of its surroundings; convective heat transfer in the solution and the surrounding air is taken into account within the framework of the Boussinesq approximation. The hereby presented theoretical treatment indicates that an initial temperature difference of the order of 1 K dissipates with a characteristic time scale of ∼1000 s; the thermal equilibration is accompanied by convective flows with a maximum velocity of ∼10(-4) m s(-1); furthermore, the temporal evolution of the temperature profile is influenced by the sign of the initial difference. These results suggest that, unless the temperature of the solution is rigorously controlled, convection may significantly compromise the interpretation of data from SECM and other electrochemical techniques, which is usually done on the basis of diffusion-only models.

  11. Toward quantitative electrochemical measurements on the nanoscale by scanning probe microscopy: environmental and current spreading effects.

    PubMed

    Arruda, Thomas M; Kumar, Amit; Jesse, Stephen; Veith, Gabriel M; Tselev, Alexander; Baddorf, Arthur P; Balke, Nina; Kalinin, Sergei V

    2013-09-24

    The application of electric bias across tip-surface junctions in scanning probe microscopy can readily induce surface and bulk electrochemical processes that can be further detected though changes in surface topography, Faradaic or conductive currents, or electromechanical strain responses. However, the basic factors controlling tip-induced electrochemical processes, including the relationship between applied tip bias and the thermodynamics of local processes, remains largely unexplored. Using the model Li-ion reduction reaction on the surface in Li-ion conducting glass ceramic, we explore the factors controlling Li-metal formation and find surprisingly strong effects of atmosphere and back electrode composition on the process. We find that reaction processes are highly dependent on the nature of the counter electrode and environmental conditions. Using a nondepleting Li counter electrode, Li particles could grow significantly larger and faster than a depleting counter electrode. Significant Li ion depletion leads to the inability for further Li reduction. Time studies suggest that Li diffusion replenishes the vacant sites after ∼12 h. These studies suggest the feasibility of SPM-based quantitative electrochemical studies under proper environmental controls, extending the concepts of ultramicroelectrodes to the single-digit nanometer scale.

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

    PubMed

    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 K(3)[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 WO(3) form.

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

    NASA Astrophysics Data System (ADS)

    Yu, Pengfei; Hu, Shuling; Shen, Shengping

    2016-08-01

    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.

  14. Soft Surfaces for Fast Characterization and Positioning of Scanning Electrochemical Microscopy Nanoelectrode Tips.

    PubMed

    Gossage, Zachary T; Simpson, Burton H; Schorr, Noah B; Rodríguez-López, Joaquín

    2016-10-18

    The testing of nanoelectrode tips for scanning electrochemical microscopy (SECM) is a slow and cumbersome task that often results in untimely electrode breakage due to crashing against a substrate. Here, we evaluated approach curves of nano- and microelectrodes to soft surfaces using SECM for a rapid and more convenient characterization and positioning protocol. Soft surfaces consisted of either a submerged argon bubble or a thin polydimethylsiloxane (PDMS) layer. While approach curves to Ar bubbles in the presence of a surfactant were promising for the characterization of microelectrode tips, their performance with nanoelectrodes was deficient. In contrast, approach curves to PDMS films allowed the rapid positioning of nanoelectrodes as small as 30 nm radius at speeds up to 5 μm/s without the risk of breakage. The nanoelectrodes were able to approach the polymer films multiple times without affecting their electrochemical performance. Furthermore, using a half-coated substrate with PDMS, nanoelectrodes could be retracted and positioned very close to the bare, hard substrate for characterization with traditional approach curves. We estimate time savings on tip characterization/positioning on the order of 10- to 100-fold. This simple procedure is easily implemented without the requirement of additional devices supplementing existing commercial SECM instruments.

  15. Electrochemical direct writing and erasing of silver nanostructures on phosphate glass using atomic force microscopy.

    PubMed

    Barna, Shama F; Jacobs, Kyle E; Mensing, Glennys A; Ferreira, Placid M

    2017-02-10

    This paper reports a liquid-free, mask-less electrochemical direct-write lithographic technique using an atomic force microscopy (AFM) probe for writing silver nanostructures in minutes on an optically transparent substrate. Under ambient conditions, silver is locally and controllably extracted to the surface of superionic (AgI)0.25 (AgPO3)0.75 glass by bringing a conductive AFM probe tip in contact with it, biasing the probe with a negative voltage, and regulating the resulting current. The growth mechanism of the resulting nanostructure is explored by extracting silver with a stationary AFM tip on the surface of the silver. A moving tip was then used to produce continuous lines, solid films and discrete dots of silver by implementing continuous and pulsed current writing approaches. The line dimensions depend on writing speed and current flowing in the electrochemical circuit, while the size and spacing of the dots depend on the parameters (magnitude, duration and frequency) of the current pulses and the writing speed of the AFM tip. Line-widths in the ∼100 nm range are demonstrated. Our investigation also shows that a threshold potential must be overcome to be able to draw and reduce silver ions on the glass surface. When polarity between the electrodes is reversed, the patterned silver ionizes back into the glass, thus offering the capability to erase and rewrite Ag patterns on the glass surface.

  16. Electrochemical direct writing and erasing of silver nanostructures on phosphate glass using atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Barna, Shama F.; Jacobs, Kyle E.; Mensing, Glennys A.; Ferreira, Placid M.

    2017-02-01

    This paper reports a liquid-free, mask-less electrochemical direct-write lithographic technique using an atomic force microscopy (AFM) probe for writing silver nanostructures in minutes on an optically transparent substrate. Under ambient conditions, silver is locally and controllably extracted to the surface of superionic (AgI)0.25 (AgPO3)0.75 glass by bringing a conductive AFM probe tip in contact with it, biasing the probe with a negative voltage, and regulating the resulting current. The growth mechanism of the resulting nanostructure is explored by extracting silver with a stationary AFM tip on the surface of the silver. A moving tip was then used to produce continuous lines, solid films and discrete dots of silver by implementing continuous and pulsed current writing approaches. The line dimensions depend on writing speed and current flowing in the electrochemical circuit, while the size and spacing of the dots depend on the parameters (magnitude, duration and frequency) of the current pulses and the writing speed of the AFM tip. Line-widths in the ∼100 nm range are demonstrated. Our investigation also shows that a threshold potential must be overcome to be able to draw and reduce silver ions on the glass surface. When polarity between the electrodes is reversed, the patterned silver ionizes back into the glass, thus offering the capability to erase and rewrite Ag patterns on the glass surface.

  17. High-speed scanning electrochemical microscopy method for substrate kinetic determination: method and theory.

    PubMed

    Kuss, Sabine; Trinh, Dao; Danis, Laurence; Mauzeroll, Janine

    2015-08-18

    Scanning electrochemical microscopy (SECM) allows imaging and analysis of a variety of biological samples, such as living cells. Up to now, it still remains a challenge to successfully decouple signals related to topography and reactivity. Furthermore, such delicate samples require careful adjustment of experimental parameters, such as scan velocity. The present study proposes a method to extract a substrate's kinetic rate by numerical modeling and experimental high speed constant height SECM imaging. This is especially useful for the determination of substrates with unknown surface reaction kinetics and large topographical features. To make this approach applicable to soft cell samples, which cannot be imaged at high velocity, a nonlinear fit strategy is presented to obtain kinetic rate values also under slow scan velocity conditions.

  18. Scanning Electrochemical Microscopy: A Comprehensive Review of Experimental Parameters from 1989 to 2015.

    PubMed

    Polcari, David; Dauphin-Ducharme, Philippe; Mauzeroll, Janine

    2016-11-23

    Scanning electrochemical microscopy (SECM) is an electroanalytical scanning probe technique capable of imaging substrate topography and local reactivity with high resolution. Since its inception in 1989, it has expanded into a wide variety of research areas including biology, corrosion, energy, kinetics, instrumental development, and surface modification. In the past 25 years, over 1800 peer-reviewed publications have focused on SECM, including several topical reviews. However, these reviews often omit key details, forcing readers to search the literature. In this review, we provide a comprehensive summary of the experimental parameters (e.g., solvents, probes, and mediators) used in all SECM publications since 1989, irrespective of the application. It can be used to rapidly assess experimental possibilities and make an informed decision about experimental design. In other words, it is a practical guide to SECM.

  19. Direct mapping of Li distribution in electrochemically lithiated graphite anodes using scanning Auger electron microscopy

    NASA Astrophysics Data System (ADS)

    Ishida, Nobuyuki; Fukumitsu, Hitoshi; Kimura, Hiroshi; Fujita, Daisuke

    2014-02-01

    The spatial distribution of Li ions in electrochemically lithiated graphite anodes for Li-ion battery is characterized by scanning Auger electron microscopy. We show that direct mapping of Li KVV peak intensity reveal the spatial distribution of intercalated Li and its chemical state in a quantitative manner. Furthermore, we demonstrate that mapping using a C KVV peak also reflects the spatial distribution of Li due to the change in the electronic properties of C atoms induced by the electrode reaction (Li intercalation). Mapping measurements on three samples with different charging states (20%, 50%, and 100%) show that at the early stage of charging Li ions do not intercalate homogenously into all the graphite particles but selectively into some specific ones with higher rates. Our method provides the criteria to evaluate structure-correlated Li intercalation from nanometer- to micrometer-scale, such as conductivity network in the electrodes due to a non-uniform morphology of binder and conductive additives.

  20. Second harmonic detection in the electrochemical strain microscopy of Ag-ion conducting glass

    DOE PAGES

    Yang, Sangmo; Okatan, Mahmut Baris; Paranthaman, Mariappan Parans; ...

    2014-11-14

    The first and second harmonic electromechanical responses and their cross-correlation in Ag-ion conducting glass were investigated using band-excitation electrochemical strain microscopy (ESM). Consecutive ESM images with increasing magnitudes of the applied AC voltage allowed observation of not only reversible surface displacement but also irreversible silver nanoparticle formation above a certain threshold voltage. The second harmonic ESM response was anticorrelated with the first harmonic response in many local regions. Furthermore, the nucleation sites of silver nanoparticles were closely related to the anti-correlated regions, specifically, with low second harmonic and high first harmonic ESM responses. The possible origins of the second harmonicmore » ESM response are discussed.« less

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

    SciTech Connect

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

    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.

  2. Direct visualization of solid electrolyte interphase formation in lithium-ion batteries with in situ electrochemical transmission electron microscopy.

    PubMed

    Unocic, Raymond R; Sun, Xiao-Guang; Sacci, Robert L; Adamczyk, Leslie A; Alsem, Daan Hein; Dai, Sheng; Dudney, Nancy J; More, Karren L

    2014-08-01

    Complex, electrochemically driven transport processes form the basis of electrochemical energy storage devices. The direct imaging of electrochemical processes at high spatial resolution and within their native liquid electrolyte would significantly enhance our understanding of device functionality, but has remained elusive. In this work we use a recently developed liquid cell for in situ electrochemical transmission electron microscopy to obtain insight into the electrolyte decomposition mechanisms and kinetics in lithium-ion (Li-ion) batteries by characterizing the dynamics of solid electrolyte interphase (SEI) formation and evolution. Here we are able to visualize the detailed structure of the SEI that forms locally at the electrode/electrolyte interface during lithium intercalation into natural graphite from an organic Li-ion battery electrolyte. We quantify the SEI growth kinetics and observe the dynamic self-healing nature of the SEI with changes in cell potential.

  3. Direct Visualization of Solid Electrolyte Interphase Formation in Lithium-Ion Batteries with In Situ Electrochemical Transmission Electron Microscopy

    SciTech Connect

    Unocic, Raymond R.; Sun, Xiao-Guang; Sacci, Robert L.; Adamczyk, Leslie A.; Alsem, Daan Hein; Dai, Sheng; Dudney, Nancy J.; More, Karren Leslie

    2014-08-01

    Complex, electrochemically driven transport processes form the basis of electrochemical energy storage devices. The direct imaging of electrochemical processes at high spatial resolution and within their native liquid electrolyte would significantly enhance our understanding of device functionality, but has remained elusive. In this work we use a recently developed liquid cell for in situ electrochemical transmission electron microscopy to obtain insight into the electrolyte decomposition mechanisms and kinetics in lithium-ion (Li-ion) batteries by characterizing the dynamics of solid electrolyte interphase (SEI) formation and evolution. Here we are able to visualize the detailed structure of the SEI that forms locally at the electrode/electrolyte interface during lithium intercalation into natural graphite from an organic Li-ion battery electrolyte. We quantify the SEI growth kinetics and observe the dynamic self-healing nature of the SEI with changes in cell potential.

  4. Scanning electrochemical microscopy as a local probe of oxygen permeability in cartilage.

    PubMed Central

    Gonsalves, M; Barker, A L; Macpherson, J V; Unwin, P R; O'Hare, D; Winlove, C P

    2000-01-01

    The use of scanning electrochemical microscopy, a high-resolution chemical imaging technique, to probe the distribution and mobility of solutes in articular cartilage is described. In this application, a mobile ultramicroelectrode is positioned close ( approximately 1 microm) to the cartilage sample surface, which has been equilibrated in a bathing solution containing the solute of interest. The solute is electrolyzed at a diffusion-limited rate, and the current response measured as the ultramicroelectrode is scanned across the sample surface. The topography of the samples was determined using Ru(CN)(6)(4-), a solute to which the cartilage matrix was impermeable. This revealed a number of pit-like depressions corresponding to the distribution of chondrocytes, which were also observed by atomic force and light microscopy. Subsequent imaging of the same area of the cartilage sample for the diffusion-limited reduction of oxygen indicated enhanced, but heterogeneous, permeability of oxygen across the cartilage surface. In particular, areas of high permeability were observed in the cellular and pericellular regions. This is the first time that inhomogeneities in the permeability of cartilage toward simple solutes, such as oxygen, have been observed on a micrometer scale. PMID:10692342

  5. Self-consistent modeling of electrochemical strain microscopy of solid electrolytes

    DOE PAGES

    Tselev, Alexander; Morozovska, Anna N.; Udod, Alexei; ...

    2014-10-10

    Electrochemical strain microscopy (ESM) employs a strong electromechanical coupling in solid ionic conductors to map ionic transport and electrochemical processes with nanometer-scale spatial resolution. To elucidate the mechanisms of the ESM image formation, we performed self-consistent numerical modeling of the electromechanical response in solid electrolytes under the probe tip in a linear, small-signal regime using the Boltzmann–Planck–Nernst–Einstein theory and Vegard's law while taking account of the electromigration and diffusion. We identified the characteristic time scales involved in the formation of the ESM response and found that the dynamics of the charge carriers in the tip-electrolyte system with blocking interfaces canmore » be described as charging of the diffuse layer at the tip-electrolyte interface through the tip contact spreading resistance. At the high frequencies used in the detection regime, the distribution of the charge carriers under the tip is governed by evanescent concentration waves generated at the tip-electrolyte interface. The ion drift length in the electric field produced by the tip determines the ESM response at high frequencies, which follows a 1/f asymptotic law. The electronic conductivity, as well as the electron transport through the electrode-electrolyte interface, do not have a significant effect on the ESM signal in the detection regime. The results indicate, however, that for typical solid electrolytes at room temperature, the ESM response originates at and contains information about the very surface layer of a sample, and the properties of the one-unit-cell-thick surface layer may significantly contribute to the ESM response, implying a high surface sensitivity and a high lateral resolution of the technique. On the other hand, it follows that a rigorous analysis of the ESM signals requires techniques that account for the discrete nature of a solid.« less

  6. Nanogap-enabled study of electrode reactions by scanning electrochemical microscopy

    NASA Astrophysics Data System (ADS)

    Nioradze, Nikoloz

    The nanogap quasi-steady-state voltammetry, developed in my work, presents the way to monitor and study rapid electron transfer reactions on macroscopic substrates of scanning electrochemical microscopy (SECM). It combines the cyclic voltammetry and SECM and monitors substrate reaction as a tip current. The resulting plot of iT versus ES features the retraceable sigmoidal shape of a quasi-steady state voltammogram although a transient peak-shape voltammogram is obtained simultaneously at the macroscopic substrate. This simplifies measurement and analysis of a quasi-steady-state voltammogram and gives information about thermodynamic as well as kinetic parameters of the reaction taking place at the interface. No charging current at the amperometric tip, high and adjustable mass transport under the tip and high spatial resolution are all advantages of quasi-steady-state voltammetry. I also introduced generalized theory for nanoscale iT-ES voltammetry of substrate reactions with arbitrary reversibility and mechanism under comprehensive experimental conditions including any substrate potential and both SECM modes (feedback and substrate generation tip collection, SG/TC). I nanofabricated submicrometer size highly reliable Pt SECM tips and found the way of protection of these tiny electrodes from the damage caused either by electrostatic discharge or electrochemical etching. Subsequent application of quasi-steady-state voltammetry and reliable nanofabricated SECM probes enabled sensitive detection of adsorption of organic impurities from air and ultrapure water to the HOPG surface as evidenced by redox reaction of ferrocenylmethyl)trimethyl ammonium (FcTMA +). Study revealed that hydrophobic contaminant layer slows down the access of hydrophilic aqueous redox species to the underlying HOPG surface, thereby yielding a lower standard rate constant, k 0. Moreover, this barrier effects stronger to a more charged form (FcTMA2+) of a redox couple so that the electron

  7. Self-consistent modeling of electrochemical strain microscopy of solid electrolytes

    SciTech Connect

    Tselev, Alexander; Morozovska, Anna N.; Udod, Alexei; Eliseev, Eugene A.; Kalinin, Sergei V.

    2014-10-10

    Electrochemical strain microscopy (ESM) employs a strong electromechanical coupling in solid ionic conductors to map ionic transport and electrochemical processes with nanometer-scale spatial resolution. To elucidate the mechanisms of the ESM image formation, we performed self-consistent numerical modeling of the electromechanical response in solid electrolytes under the probe tip in a linear, small-signal regime using the Boltzmann–Planck–Nernst–Einstein theory and Vegard's law while taking account of the electromigration and diffusion. We identified the characteristic time scales involved in the formation of the ESM response and found that the dynamics of the charge carriers in the tip-electrolyte system with blocking interfaces can be described as charging of the diffuse layer at the tip-electrolyte interface through the tip contact spreading resistance. At the high frequencies used in the detection regime, the distribution of the charge carriers under the tip is governed by evanescent concentration waves generated at the tip-electrolyte interface. The ion drift length in the electric field produced by the tip determines the ESM response at high frequencies, which follows a 1/f asymptotic law. The electronic conductivity, as well as the electron transport through the electrode-electrolyte interface, do not have a significant effect on the ESM signal in the detection regime. The results indicate, however, that for typical solid electrolytes at room temperature, the ESM response originates at and contains information about the very surface layer of a sample, and the properties of the one-unit-cell-thick surface layer may significantly contribute to the ESM response, implying a high surface sensitivity and a high lateral resolution of the technique. On the other hand, it follows that a rigorous analysis of the ESM signals requires techniques that account for the discrete nature of a solid.

  8. Determination of diffusion coefficient in gel and in aqueous solutions using scanning electrochemical microscopy.

    PubMed

    Csóka, Balázs; Nagy, Géza

    2004-10-29

    Diffusion coefficient of different species in different media is an important property needed in scientific research and practice. A method taking advantage on the special capability of scanning electrochemical microscopy (SECM) is described for the easy and accurate measurement of diffusion coefficient. The method is based on detecting the concentration-time transients with appropriate electrochemical microsensor positioned at the close vicinity of a miniature dose-source device. At a given time (ti), a small dose of the investigated species is introduced. The Deltatmax=(tcmax-ti) value and the distance (d=x+Deltaxn) between the source and the detector microelectrode are used for the calculation of D. While the original set distance (x) cannot be accurately measured in the micrometer scale, the tip travel distance (Deltaxn) of the microscope is well defined. Collecting a few Deltatmax-(x+Deltaxn) data pairs, a reliable value of the diffusion coefficient can be obtained. The procedure is simple, and no exact knowledge of the introduced dose is needed. Two ways of sample dose delivery were used: on the one hand, coulometric generation with current-controlled electric pulse using micro-disc electrode, and on the other one, pressure ejection of a nano-droplet from a glass micropipette. Diffusion coefficient of I2, H2O2, [Ru(NH3)6]Cl3 and K3[Fe(CN)6] were measured in solution and in agarose gel phases of different composition. The effect of polyelectrolyte ion exchangers on the diffusion of the investigated species was checked.

  9. Quantification of photoelectrogenerated hydroxyl radical on TiO2 by surface interrogation scanning electrochemical microscopy.

    PubMed

    Zigah, Dodzi; Rodríguez-López, Joaquín; Bard, Allen J

    2012-10-05

    The surface interrogation mode of scanning electrochemical microscopy (SI-SECM) was used for the detection and quantification of adsorbed hydroxyl radical ˙OH((ads)) generated photoelectrochemically at the surface of a nanostructured TiO(2) substrate electrode. In this transient technique, a SECM tip is used to generate in situ a titrant from a reversible redox pair that reacts with the adsorbed species at the substrate. This reaction produces an SECM feedback response from which the amount of adsorbate and its decay kinetics can be obtained. The redox pair IrCl(6)(2-/3-) offered a reactive, selective and stable surface interrogation agent under the strongly oxidizing conditions of the photoelectrochemical cell. A typical ˙OH((ads)) saturation coverage of 338 μC cm(-2) was found in our nanostructured samples by its reduction with the electrogenerated IrCl(6)(3-). The decay kinetics of ˙OH((ads)) by dimerization to produce H(2)O(2) were studied through the time dependence of the SI-SECM signal and the surface dimerization rate constant was found to be ~k(OH) = 2.2 × 10(3) mol(-1) m(2) s(-1). A radical scavenger, such as methanol, competitively consumes ˙OH((ads)) and yields a shorter SI-SECM transient, where a pseudo-first order rate analysis at 2 M methanol yields a decay constant of k'(MeOH) ~ 1 s(-1).

  10. Scanning electrochemical microscopy, 52. Bipolar conductance technique at ultramicroelectrodes for resistance measurements.

    PubMed

    LeSuer, Robert J; Fan, Fu-Ren F; Bard, Allen J

    2004-12-01

    The bipolar conductance, BICON, technique for the measurement of solution resistance, based on the application of microsecond current pulses, as originally described by Enke and co-workers for measurements with conventional electrodes, was extended for use with ultramicroelectrodes, with a focus on its application in scanning electrochemical microscopy (SECM). When the plateau time used to make the measurement lies within the BICON conditions, the solution conductance can be obtained directly from the output without the need for calibration curves. However, decreasing the size of the ultramicroelectrode decreases the range of values that satisfy these conditions, and one must resort to calibration curves to obtain solution conductance from the measured current, which was nevertheless found to be proportional to electrolyte concentration with electrodes as small as 5 mum in diameter. BICON/SECM approach curves over insulating substrates followed SECM negative feedback theory and approach curves in the presence of low (micromolar) or no added electrolyte are possible once the background conductivity is taken into account. Approach curves to a conducting substrate at open circuit potential are influenced by the solution time constant (solution resistance at the electrode tip x electrode double layer capacitance), which is a function of the tip/substrate distance, as well as the substrate size.

  11. Digital simulation of scanning electrochemical microscopy approach curves to enzyme films with Michaelis-Menten kinetics.

    PubMed

    Burchardt, Malte; Träuble, Markus; Wittstock, Gunther

    2009-06-15

    The formalism for simulating scanning electrochemical microscopy (SECM) experiments by boundary element methods in three space coordinates has been extended to allow consideration of nonlinear boundary conditions. This is achieved by iteratively refining the boundary conditions that are encoded in a boundary condition matrix. As an example, the simulations are compared to experimental approach curves in the SECM feedback mode toward samples modified with glucose oxidase (GOx). The GOx layer was prepared by the layer-by-layer assembly of polyelectrolytes using glucose oxidase as one of the polyelectrolytes. The comparison of the simulated and experimental curves showed that under a wide range of experimentally accessible conditions approximations of the kinetics at the sample by first order models yield misleading results. The approach curves differ also qualitatively from curves calculated with first order models. As a consequence, this may lead to severe deviations when such curves are fitted to first order kinetic models. The use of linear approximations to describe the enzymatic reaction in SECM feedback experiments is justified only if the ratio of the mediator and Michaelis-Menten constant is equal to or smaller than 0.1 (deviation less than 10%).

  12. Scanning Electrochemical Microscopy as a Novel Proximity Sensor for Atraumatic Cochlear Implant Insertion

    PubMed Central

    Velmurugan, J.; Mirkin, M. V.; Svirsky, M. A.; Lalwani, A. K.; Llinas, R. R.

    2014-01-01

    A growing number of minimally invasive surgical and diagnostic procedures require the insertion of an optical, mechanical, or electronic device in narrow spaces inside a human body. In such procedures, precise motion control is essential to avoid damage to the patient’s tissues and/or the device itself. A typical example is the insertion of a cochlear implant which should ideally be done with minimum physical contact between the moving device and the cochlear canal walls or the basilar membrane. Because optical monitoring is not possible, alternative techniques for sub millimeter-scale distance control can be very useful for such procedures. The first requirement for distance control is distance sensing. We developed a novel approach to distance sensing based on the principles of scanning electrochemical microscopy (SECM). The SECM signal, i.e., the diffusion current to a microelectrode, is very sensitive to the distance between the probe surface and any electrically insulating object present in its proximity. With several amperometric microprobes fabricated on the surface of an insertable device, one can monitor the distances between different parts of the moving implant and the surrounding tissues. Unlike typical SECM experiments, in which a disk-shaped tip approaches a relatively smooth sample, complex geometries of the mobile device and its surroundings make distance sensing challenging. Additional issues include the possibility of electrode surface contamination in biological fluids and the requirement for a biologically compatible redox mediator. PMID:24845292

  13. Scanning electrochemical microscopy of membrane transport in the reverse imaging mode.

    PubMed

    Uitto, O D; White, H S

    2001-02-01

    Scanning electrochemical microscopy (SECM), operated in reverse imaging mode (RIM), has been used to visualize the steady-state transport of molecules entering into porous membranes. RIM imaging is advantageous for investigating transport across biological membranes in situations where the SECM tip can access only the exterior membrane surface. Examples of RIM images of a synthetic membrane (mica with pores filled with the ion-selective polymer Nafion) and a biological membrane (hairless mouse skin) recorded during diffusive and iontophoretic transport, are reported. RIM imaging during diffusive transport allows visualization of the depletion of solute molecules in the solution adjacent to the pore openings. However, an accumulation of solute molecules above the pore opening is observed during iontophoresis, which is a consequence of the separation of the solute from the solvent (i.e., ultrafiltration). The separation results from differences in the rates of molecule transfer across the pore/solution interface when electroosmotic flow is operative. The results suggest that RIM imaging may be useful for measuring the kinetics of interfacial molecule transfer at biological membranes.

  14. Scanning electrochemical microscopy #54. Application to the study of heterogeneous catalytic reactions-hydrogen peroxide decomposition.

    PubMed

    Fernández, José L; Hurth, Cedric; Bard, Allen J

    2005-05-19

    A scanning electrochemical microscopy (SECM) approach for the analysis of heterogeneous catalytic reactions at solid-liquid interfaces is described and applied. In this scheme, reactant, generated at a tip, undergoes a reaction (e.g., disproportionation) at the substrate. The theoretical background for this study, performed by digital simulations using a finite difference method, considers a chemical reaction at the substrate with general stoichiometry. In this case, the fraction of regenerated mediator (nu(S)) may differ with respect to a substrate reaction that is the reverse of the tip reaction, resulting in an asymmetric mediator loop. Simulated tip current transients and approach curves at different values of the kinetic rate constant for reactions where nu(S) < 1 were used to analyze this new SECM situation. This approach was used to study the catalytic decomposition of hydrogen peroxide (HO2- --> 1/2O2 + OH-), where nu(S) = 0.5, on supported catalysts. A gold-mercury amalgam tip was used to quantitatively reduce dissolved O2 (mediator) to HO2-, which was decomposed back to oxygen at the catalyst substrate. Rate constants for the decomposition reaction on immobilized catalase and Pt particles were measured at different pH values by the correlation of experimental approach curves with the theoretical dependencies.

  15. Characterization of LiMn2O4 cathodes by electrochemical strain microscopy

    SciTech Connect

    Alikin, D. O.; Ievlev, A. V.; Luchkin, S. Yu.; Turygin, A. P.; Shur, V. Ya.; Kalinin, S. V.; Kholkin, A. L.

    2016-03-15

    Electrochemical strain microscopy (ESM) is a scanning probe microscopy(SPM) method in which the local electrodiffusion is probed via application of AC voltage to the SPM tip and registration of resulting electrochemical strain. In this study, we implemented ESM to measure local strain in bulk LiMn2O4 cathodes of a commercial Li-battery in different states of charge to investigate distribution of Li-ion mobility and concentration. Ramped AC ESM imaging and voltage spectroscopy were used to find the most reliable regime of measurements allowing separating and diminishing different contributions to ESM. This is not a trivial task due to complex geometry of the sample and various obstacles resulting in less predictable contributions of different origins into ESM response: electrostatic tip–surface interactions, charge injection, electrostriction, and flexoelectricity. Finally, understanding and control of these contributions is an important step towards quantitative interpretation of ESM data.

  16. Scanning tunneling microscopy of electrochemically activated platinum surfaces. A direct ex-situ determination of the electrode nanotopography

    SciTech Connect

    Vazquez, L.; Gomez, J.; Baro, A.M.; Garcia, N.; Marcos, M.L.; Velasco, J.G.; Vara, J.M.; Arvia, A.J.; Presa, J.; Garcia, A.; Aguilar, M.

    1987-03-18

    A direct scanning tunneling microscopy ex-situ determination on the nanometer scale of the topography of electrochemically highly activated platinum electrodes is presented. A correlation between catalytic activity and surface microtopography becomes evident. This result gives support to a structural model for the activated electrode surface. In the model, a volume with a pebble-like structure allows electrocatalytic processes to occur practically free of diffusion relaxation contributions under usual voltammetric conditions.

  17. Microstamped Petri Dishes for Scanning Electrochemical Microscopy Analysis of Arrays of Microtissues

    PubMed Central

    Sridhar, Adithya; de Boer, Hans L.; van den Berg, Albert; Le Gac, Séverine

    2014-01-01

    While scanning electrochemical microscopy (SECM) is a powerful technique for non-invasive analysis of cells, SECM-based assays remain scarce and have been mainly limited so far to single cells, which is mostly due to the absence of suitable platform for experimentation on 3D cellular aggregates or microtissues. Here, we report stamping of a Petri dish with a microwell array for large-scale production of microtissues followed by their in situ analysis using SECM. The platform is realized by hot embossing arrays of microwells (200 μm depth; 400 μm diameter) in commercially available Petri dishes, using a PDMS stamp. Microtissues form spontaneously in the microwells, which is demonstrated here using various cell lines (e.g., HeLa, C2C12, HepG2 and MCF-7). Next, the respiratory activity of live HeLa microtissues is assessed by monitoring the oxygen reduction current in constant height mode and at various distances above the platform surface. Typically, at a 40 μm distance from the microtissue, a 30% decrease in the oxygen reduction current is measured, while above 250 μm, no influence of the presence of the microtissues is detected. After exposure to a model drug (50% ethanol), no such changes in oxygen concentration are found at any height in solution, which reflects that microtissues are not viable anymore. This is furthermore confirmed using conventional live/dead fluorescent stains. This live/dead assay demonstrates the capability of the proposed approach combining SECM and microtissue arrays formed in a stamped Petri dish for conducting cellular assays in a non-invasive way on 3D cellular models. PMID:24690887

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

    SciTech Connect

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

    2012-06-15

    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 {approx}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 Degree-Sign variability in cone angle and 1.5 mm controllability in cone length were achieved, while routinely producing ultra-sharp probes.

  19. Potential-dependent adsorption/desorption behavior of perfluorosulfonated ionomer on a gold electrode surface studied by cyclic voltammetry, electrochemical quartz microbalance, and electrochemical atomic force microscopy.

    PubMed

    Masuda, Takuya; Ikeda, Kota; Uosaki, Kohei

    2013-02-19

    Potential-dependent adsorption/desorption behavior of perfluorosulfonated ionomer (PFSI) on a gold electrode was investigated by cyclic voltammetry (CV), electrochemical quartz crystal microbalance (EQCM), and electrochemical atomic force microscopy (EC-AFM) in a Nafion (i.e., PFSI) dispersed aqueous solution without any other electrolyte. It was found that PFSI serves as an electrolyte and that electrochemical measurements can be performed in this solution without any significant IR drop. PFSI molecules were adsorbed on the Au surface in the lying-down configuration in the potential range between 0 and 0.45 V, the amount of adsorbed PFSI increased when the potential was made more positive than 0.75 V, and the adsorbed PFSI fully desorbed from the surface at potentials more positive than 1.4 V where gold oxide was formed. Once the gold oxide had been reduced, PFSI readsorbed on the surface, albeit slowly. PFSI desorbed from the surface as the potential was made more negative than 0 V. These processes took place reversibly.

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

    SciTech Connect

    Gupta, Sanju Price, Carson

    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

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

    NASA Astrophysics Data System (ADS)

    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

  2. Iontophoretic transport through porous membranes using scanning electrochemical microscopy: application to in vitro studies of ion fluxes through skin.

    PubMed

    Scott, E R; White, H S; Phipps, J B

    1993-06-01

    Scanning electrochemical microscopy (SECM) is used to map localized iontophoretic fluxes of electroactive species through porous membranes. A method is described that allows both the rate of transport of species from a microscopic pore and the pore's diameter to be measured. SECM images and analyses of synthetic porous membranes (track-etched polycarbonate and mica membranes) and hairless mouse skin are reported. Preliminary analysis of SECM images of the mouse skin indicates that a significant percentage of the iontophoretic flux occurs through pores associated with hair follicles.

  3. The study of multireactional electrochemical interfaces via a tip generation/substrate collection mode of scanning electrochemical microscopy: the hydrogen evolution reaction for Mn in acidic solution.

    PubMed

    Leonard, Kevin C; Bard, Allen J

    2013-10-23

    We report a new method of scanning electrochemical microscopy (SECM) that can be used to separate multireactional electrochemical interfaces, i.e., electrodes at which two or more reactions occur (and hence two partial currents flow) at the same time. This was done with a modified tip generation/substrate collection mode where the two reactions occur on the tip electrode, and the substrate electrode is held at a potential to collect only one of the products, allowing the determination of the individual partial currents. Thus, by using the substrate electrode current and the difference between the tip and substrate electrode currents, the two reactions occurring on the tip electrode can be separated. As a test case for this new method, we investigated proton reduction on Mn, a reaction that, because of the highly corrosive nature of Mn, to our knowledge has never before been directly measured. This test was carried out using a Mn tip electrode and a Pt substrate electrode. Using a three-dimensional COMSOL Multiphysics simulation, we were able to accurately determine the tip/substrate distance with this electrode, and by fitting simulations to experimental data, we were able to determine an exchange current density, log(j(0)) = -4.7 ± 0.7 A cm(-2), for proton reduction on Mn in strong acid. This result corrects a literature value and was used in a pattern recognition algorithm reported in a companion manuscript.

  4. Visualizing and Calculating Tip-Substrate Distance in Nanoscale Scanning Electrochemical Microscopy Using 3-Dimensional Super-Resolution Optical Imaging.

    PubMed

    Sundaresan, Vignesh; Marchuk, Kyle; Yu, Yun; Titus, Eric J; Wilson, Andrew J; Armstrong, Chadd M; Zhang, Bo; Willets, Katherine A

    2017-01-03

    We report a strategy for the optical determination of tip-substrate distance in nanoscale scanning electrochemical microscopy (SECM) using three-dimensional super-resolution fluorescence imaging. A phase mask is placed in the emission path of our dual SECM/optical microscope, generating a double helix point spread function at the image plane, which allows us to measure the height of emitting objects relative to the focus of the microscope. By exciting both a fluorogenic reaction at the nanoscale electrode tip as well as fluorescent nanoparticles at the substrate, we are able to calculate the tip-substrate distance as the tip approaches the surface with precision better than 25 nm. Attachment of a fluorescent particle to the insulating sheath of the SECM tip extends this technique to nonfluorogenic electrochemical reactions. Correlated electrochemical and optical determination of tip-substrate distance yielded excellent agreement between the two techniques. Not only does super-resolution imaging offer a secondary feedback mechanism for measuring the tip-sample gap during SECM experiments, it also enables facile tip alignment and a strategy for accounting for electrode tilt relative to the substrate.

  5. In situ transmission electron microscopy observation of electrochemical sodiation of individual Co₉S₈-filled carbon nanotubes.

    PubMed

    Su, Qingmei; Du, Gaohui; Zhang, Jun; Zhong, Yijun; Xu, Bingshe; Yang, Yuehai; Neupane, Suman; Li, Wenzhi

    2014-04-22

    The comprehension of fundamental electrochemical behavior and sodiation mechanism is critical for the design of high-performance electrode materials for sodium-ion (Na-ion) batteries. In this paper, the electrochemical sodiation process and microstructure evolution of individual Co9S8-filled carbon nanotubes (CNTs) have been directly visualized and studied using in situ transmission electron microscopy. Upon the first sodiation, a reaction front propagates progressively along the filling nanowire, causing the filled CNT to inflate. The filled CNTs behave differently depending on their structures and the magnitude of the sodiation voltage. For a Co9S8-filled CNT with an open end, the sodiated Co9S8 filler shows a substantial axial elongation of 120.8% and a small radial swelling due to the extrusion of CNT walls. In contrast, the closed CNT shows a major radial expansion of 40.6% and a small axial elongation because of the mechanical confinement of the carbon shells. After sodiation, the spacing between the carbon shells increases from 3.4 to 3.8 Å due to the Na(+)-ion insertion and the single-crystalline Co9S8 filler converts to numerous Co nanograins dispersed in a Na2S matrix. Compared with the gentle microstructure evolution of the CNT under small charging voltage, a strong electrochemical reaction accompanying drastic swelling and fracturing of CNT shells is observed for the CNT electrode under large charging voltage. Our observations provide direct evidence and important insights for the electrochemical process of CNT-based composite materials in Na-ion batteries.

  6. Scanning electrochemical microscopy studies of micropatterned copper sulfide (Cu(x)S) thin films fabricated by a wet chemistry method.

    PubMed

    Chen, Miao; Zhao, Jing; Zhao, Xiaocui

    2011-05-30

    Patterned copper sulfide (Cu(x)S) microstructures on Si (1 1 1) wafers were successfully fabricated by a relatively simple solution growth method using copper sulfate, ethylenediaminetetraacetate and sodium thiosulfate aqueous solutions as precursors. The Cu(x)S particles were selectively deposited on a patterned self-assembled monolayer of 3-aminopropyltriethoxysilane regions created by photolithography. To obtain high quality Cu(x)S films, preparative conditions such as concentration, proportion, pH and temperature of the precursor solutions were optimized. Various techniques such as optical microscopy, atomic force microscopy (AFM), X-ray diffraction, optical absorption and scanning electrochemical microscopy (SECM) were employed to examine the topography and properties of the micro-patterned Cu(x)S films. Optical microscopy and AFM results indicated that the Cu(x)S micro-pattern possessed high selectivity and clear edge resolution. From combined X-ray diffraction analysis and optical band gap calculations we conclude that Cu(9)S(5) (digenite) was the main phase within the resultant Cu(x)S film. Both SECM image and cyclic voltammograms confirmed that the Cu(x)S film had good electrical conductivity. Moreover, from SECM approach curve analysis, the apparent electron-transfer rate constant (k) in the micro-pattern of Cu(x)S dominated surface was estimated as 0.04 cm/s. The SECM current map showed high edge acuity of the micro-patterned Cu(x)S.

  7. Scanning electrochemical microscopy studies of micropatterned copper sulfide (CuxS) thin films fabricated by a wet chemistry method

    PubMed Central

    Chen, Miao; Zhao, Jing; Zhao, Xiaocui

    2011-01-01

    Patterned copper sulfide (CuxS) microstructures on Si (1 1 1) wafers were successfully fabricated by a relatively simple solution growth method using copper sulfate, ethylenediaminetetraacetate and sodium thiosulfate aqueous solutions as precursors. The CuxS particles were selectively deposited on a patterned self-assembled monolayer of 3-aminopropyltriethoxysilane regions created by photolithography. To obtain high quality CuxS films, preparative conditions such as concentration, proportion, pH and temperature of the precursor solutions were optimized. Various techniques such as optical microscopy, atomic force microscopy (AFM), X-ray diffraction, optical absorption and scanning electrochemical microscopy (SECM) were employed to examine the topography and properties of the micro-patterned CuxS films. Optical microscopy and AFM results indicated that the CuxS micro-pattern possessed high selectivity and clear edge resolution. From combined X-ray diffraction analysis and optical band gap calculations we conclude that Cu9S5 (digenite) was the main phase within the resultant CuxS film. Both SECM image and cyclic voltammograms confirmed that the CuxS film had good electrical conductivity. Moreover, from SECM approach curve analysis, the apparent electron-transfer rate constant (k) in the micro-pattern of CuxS dominated surface was estimated as 0.04 cm/s. The SECM current map showed high edge acuity of the micro-patterned CuxS. PMID:21785491

  8. Quantitative Visualization of Molecular Delivery and Uptake at Living Cells with Self-Referencing Scanning Ion Conductance Microscopy-Scanning Electrochemical Microscopy.

    PubMed

    Page, Ashley; Kang, Minkyung; Armitstead, Alexander; Perry, David; Unwin, Patrick R

    2017-03-07

    A multifunctional dual-channel scanning probe nanopipet that enables simultaneous scanning ion conductance microscopy (SICM) and scanning electrochemical microscopy (SECM) measurements is demonstrated to have powerful new capabilities for spatially mapping the uptake of molecules of interest at living cells. One barrel of the probe is filled with electrolyte and the molecules of interest and is open to the bulk solution for both topographical feedback and local delivery to a target interface, while a solid carbon electrode in the other barrel measures the local concentration and flux of the delivered molecules. This setup allows differentiation in molecular uptake rate across several regions of single cells with individual measurements at nanoscale resolution. Further, operating in a "hopping mode", where the probe is translated toward the interface (cell) at each point allows self-referencing to be employed, in which the carbon electrode response is calibrated at each and every pixel in bulk for comparison to the measurement near the surface. This is particularly important for measurements in living systems where an electrode response may change over time. Finite element method (FEM) modeling places the technique on a quantitative footing to allow the response of the carbon electrode and local delivery rates to be quantified. The technique is extremely versatile, with the local delivery of molecules highly tunable via control of the SICM bias to promote or restrict migration from the pipet orifice. It is expected to have a myriad of applications from drug delivery to screening catalysts.

  9. Note: Circuit design for direct current and alternating current electrochemical etching of scanning probe microscopy tips

    NASA Astrophysics Data System (ADS)

    Jobbins, Matthew M.; Raigoza, Annette F.; Kandel, S. Alex

    2012-03-01

    We present control circuits designed for electrochemically etching, reproducibly sharp STM probes. The design uses an Arduino UNO microcontroller to allow for both ac and dc operation, as well as a comparator driven shut-off that allows for etching to be stopped in 0.5-1 μs. The Arduino allows the instrument to be customized to suit a wide variety of potential applications without significant changes to hardware. Data is presented for coarse chemical etching of 80:20 platinum-iridium, tungsten, and nickel tips.

  10. Qualitative and quantitative detection of DNA amplified with HRP-modified SiO2 nanoparticles using scanning electrochemical microscopy.

    PubMed

    Fan, Huajun; Jiao, Fang; Chen, Hong; Zhang, Fan; Wang, Qingjiang; He, Pingang; Fang, Yuzhi

    2013-09-15

    Qualitative and quantitative detection of DNA was achieved by a "sandwich" DNA sensor through SG/TC (substrate generation and tip collection) mode of scanning electrochemical microscopy (SECM). The "sandwich" DNA structure was formed by the hybridization of thiol-tethered oligodeoxynucleotide probes (capture probe), assembled on the gold substrate surface, with target DNA and biotinylated indicator probe. HRP (horseradish peroxidase)-wrapped SiO2 nanoparticles were linked to the sandwich structure through biotin-streptavidin interaction. Hydroquinone (H2Q) was oxidized to benzoquinone (BQ) at the modified substrate surface where sequence-specific hybridization had occurred through the HRP-catalyzed reaction in the presence of H2O2. The detection was based on the reduction of BQ generated on the modified substrate by SECM tip. For SECM imaging experiment, we structured the microsensor platform through localized desorption of 1-dodecanethiol monolayer. Approach curves were employed for quantitative detection of DNA concentration. The detection limit of complementary DNA was as low as 0.8pM. This technique is promising for the application on electrochemical DNA chip.

  11. Fabrication and Demonstration of Mercury Disc-Well Probes for Stripping-Based Cyclic Voltammetry Scanning Electrochemical Microscopy.

    PubMed

    Barton, Zachary J; Rodríguez-López, Joaquín

    2017-03-07

    Scanning electrochemical microscopy (SECM) is a rising technique for the study of energy storage materials. Hg-based probes allow the extension of SECM investigations to ionic processes, but the risk of irreversible Hg amalgam saturation limits their operation to rapid timescales and dilute analyte solutions. Here, we report a novel fabrication protocol for Hg disc-well ultramicroelectrodes (UMEs), which retain access to stripping information but are less susceptible to amalgam saturation than traditional Hg sphere-caps or thin-films. The amalgamation and stripping behaviors of Hg disc-well UMEs are compared to those of traditional Hg sphere-cap UMEs and corroborated with data from finite element simulations. The improved protection against amalgam saturation allows Hg disc-wells to operate safely in highly concentrated environments at long timescales. The utility of the probes for bulk measurements extends also to SECM studies, where the disc geometry facilitates small tip-substrate gaps and improves both spatial and temporal resolution. Because they can carry out slow, high-resolution anodic stripping voltammetry approaches and imaging in concentrated solutions, Hg disc-well electrodes fill a new analytical niche for studies of ionic reactivity and are a valuable addition to the electrochemical toolbox.

  12. Study on the Electrochemical Reaction Mechanism of ZnFe2O4 by In Situ Transmission Electron Microscopy

    PubMed Central

    Su, Qingmei; Wang, Shixin; Yao, Libing; Li, Haojie; Du, Gaohui; Ye, Huiqun; Fang, Yunzhang

    2016-01-01

    A family of mixed transition–metal oxides (MTMOs) has great potential for applications as anodes for lithium ion batteries (LIBs). However, the reaction mechanism of MTMOs anodes during lithiation/delithiation is remain unclear. Here, the lithiation/delithiation processes of ZnFe2O4 nanoparticles are observed dynamically using in situ transmission electron microscopy (TEM). Our results suggest that during the first lithiation process the ZnFe2O4 nanoparticles undergo a conversion process and generate a composite structure of 1–3 nm Fe and Zn nanograins within Li2O matrix. During the delithiation process, volume contraction and the conversion of Zn and Fe take place with the disappearance of Li2O, followed by the complete conversion to Fe2O3 and ZnO not the original phase ZnFe2O4. The following cycles are dominated by the full reversible phase conversion between Zn, Fe and ZnO, Fe2O3. The Fe valence evolution during cycles evidenced by electron energy–loss spectroscopy (EELS) techniques also exhibit the reversible conversion between Fe and Fe2O3 after the first lithiation, agreeing well with the in situ TEM results. Such in situ TEM observations provide valuable phenomenological insights into electrochemical reaction of MTMOs, which may help to optimize the composition of anode materials for further improved electrochemical performance. PMID:27306189

  13. Scanning Electrochemical Microscopy of One-Dimensional Nanostructure: Effects of Nanostructure Dimensions on the Tip Feedback Current under Unbiased Conditions

    PubMed Central

    Xiong, Hui; Kim, Jiyeon; Kim, Eunkyoung; Amemiya, Shigeru

    2009-01-01

    Scanning electrochemical microscopy (SECM) is developed as a powerful approach to electrochemical characterization of individual one-dimensional (1D) nanostructures under unbiased conditions. 1D nanostructures comprise high-aspect-ratio materials with both nanoscale and macroscale dimensions such as nanowires, nanotubes, nanobelts, and nanobands. Finite element simulations demonstrate that the feedback current at a disk-shaped ultramicroelectrode tip positioned above an unbiased nanoband, as prepared on an insulating substrate, is sensitive to finite dimensions of the band, i.e., micrometer length, nanometer width, and nanometer height from the insulating surface. The electron-transfer rate of a redox mediator at the nanoband surface depends not only on the intrinsic rate but also on the open-circuit potential of the nanoband, which is determined by the dimensions of the nanoband as well as the tip inner and outer radii, and tip–substrate distance. The theoretical predictions are confirmed experimentally by employing Au nanobands as fabricated on a SiO2 surface by electron-beam lithography, thereby yielding well defined dimensions of 100 or 500 nm in width, 47 nm in height, and 50 μm in length. A 100 nm-wide nanoband can be detected by SECM imaging with ∼2 μm-diameter tips although the tip feedback current is compromised by finite electron-transfer kinetics for Ru(NH3)63+ at the nanoband surface. PMID:20160938

  14. Monitoring Scanning Electrochemical Microscopy Approach Curves with Mid-Infrared Spectroscopy – Towards a Novel Current-Independent Positioning Mode

    PubMed Central

    Wang, Liqun; Kranz, Christine; Mizaikoff, Boris

    2010-01-01

    Single-bounce attenuated total reflection infrared spectroscopy in the 3–20 µm range (MIR) has been combined with scanning electrochemical microscopy (SECM) for in situ spectroscopic detection of electrochemically induced localized surface modifications using an ultramicroelectrode (UME). In this study, a novel current-independent approach for positioning the UME in aqueous electrolyte solution is presented using either changes of IR absorption intensity associated with borosilicate glass (BSG), which is used as shielding material of the UME wire, or by monitoring IR changes of the water spectrum within the penetration depth of the evanescent field due to displacement of water molecules in the volume between the sample surface and the UME within the evanescent field. The experimental results show that the UME penetrates into the exponentially decaying evanescent field in close vicinity (a few µm) to the ATR crystal surface. Hence, the resulting intensity changes of the IR absorption spectra for borosilicate glass (increase) and for water (decrease), can be used to determine the position of the UME relative to the ATR crystal surface independent of the current measured at the UME. PMID:20329757

  15. Identical Location Transmission Electron Microscopy Imaging of Site-Selective Pt Nanocatalysts: Electrochemical Activation and Surface Disordering.

    PubMed

    Arán-Ais, Rosa M; Yu, Yingchao; Hovden, Robert; Solla-Gullón, Jose; Herrero, Enrique; Feliu, Juan M; Abruña, Héctor D

    2015-12-02

    We have employed identical location transmission electron microscopy (IL-TEM) to study changes in the shape and morphology of faceted Pt nanoparticles as a result of electrochemical cycling; a procedure typically employed for activating platinum surfaces. We find that the shape and morphology of the as-prepared hexagonal nanoparticles are rapidly degraded as a result of potential cycling up to +1.3 V. As few as 25 potential cycles are sufficient to cause significant degradation, and after about 500-1000 cycles the particles are dramatically degraded. We also see clear evidence of particle migration during potential cycling. These finding suggest that great care must be exercised in the use and study of shaped Pt nanoparticles (and related systems) as electrocatlysts, especially for the oxygen reduction reaction where high positive potentials are typically employed.

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

    SciTech Connect

    Varenyk, O. V.; Silibin, M. V.; Kiselev, Dmitri A.; Eliseev, E. A.; Kalinin, Sergei V.; Morozovska, A. N.

    2015-08-19

    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. Furthermore, 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.

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

    DOE PAGES

    Varenyk, O. V.; Silibin, M. V.; Kiselev, Dmitri A.; ...

    2015-08-19

    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. Furthermore, 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,more » which are of potential interest for flexible and high-density non-volatile memory devices.« less

  18. Real-time mapping of a hydrogen peroxide concentration profile across a polymicrobial bacterial biofilm using scanning electrochemical microscopy.

    PubMed

    Liu, Xiuhui; Ramsey, Matthew M; Chen, Xiaole; Koley, Dipankar; Whiteley, Marvin; Bard, Allen J

    2011-02-15

    Quantitative detection of hydrogen peroxide in solution above a Streptococcus gordonii (Sg) bacterial biofilm was studied in real time by scanning electrochemical microscopy (SECM). The concentration of hydrogen peroxide was determined to be 0.7 mM to 1.6 mM in the presence of 10 mM glucose over a period of 2 to 8 h. The hydrogen peroxide production measured was higher near the biofilm surface in comparison to Sg grown planktonically. Differential hydrogen peroxide production was observed both by fluorometric as well as by SECM measurements. The interaction between two different species in a bacterial biofilm of Sg and Aggregatibacter actinomycetemcomitans (Aa) in terms of hydrogen peroxide production was also studied by SECM. One-directional y-scan SECM measurements showed the unique spatial mapping of hydrogen peroxide concentration across a mixed species biofilm and revealed that hydrogen peroxide concentration varies greatly dependent upon local species composition.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Adlayer structure of octa-alkoxy-substituted copper(II) phthalocyanine on Au(111) by electrochemical scanning tunneling microscopy.

    PubMed

    Wang, Li; Ou-Yang, Liangyue; Yau, Shueh-Lin

    2008-01-01

    Electrochemical scanning tunneling microscopy (ECSTM) has been used to examine the adlayer of octa-alkoxy-substituted copper(II) phthalocyanines (CuPc(OC(8)H(17))(8)) on Au(111) in 0.1 M HClO(4), where the molecular adlayer was prepared by spontaneous adsorption from a benzene solution containing this molecule. Topography STM scans revealed long-range ordered, interweaved arrays of CuPc(OC(8)H(17))(8) with coexistent rectangular and hexagonal symmetries. High-quality STM molecular resolution yielded the internal molecular structure and the orientation of CuPc(OC(8)H(17))(8) admolecules. These STM results could shed insight into the method of generating ordered molecular assemblies of phthalocyanine molecules with long-chained substitutes on metal surface.

  1. Novel Protein Crystal Growth Electrochemical Cell For Applications in X-ray Diffraction and Atomic Force Microscopy

    SciTech Connect

    G Gil-Alvaradejo; R Ruiz-Arellano; C Owen; A Rodriguez-Romero; E Rudino-Pinera; M Antwi; V Stojanoff; A Moreno

    2011-12-31

    A new crystal growth cell based on transparent indium tin oxide (ITO) glass-electrodes for electrochemically assisted protein crystallization allows for reduced nucleation and crystal quality enhancement. The crystallization behavior of lysozyme and ferritin was monitored as a function of the electric current applied to the growth cell. The X-ray diffraction analysis showed that for specific currents, the crystal quality is substantially improved. No conformational changes were observed in the 3D crystallographic structures determined for crystals grown under different electric current regimes. Finally, the strong crystal adhesion on the surface of ITO electrode because of the electroadhesion allows a sufficiently strong fixing of the protein crystals, to undergo atomic force microscopy investigations in a fluid cell.

  2. I Situ Electrochemical Scanning Tunneling Microscopy Study of Dealloying and Stress Corrosion Cracking of Copper - Alloys.

    NASA Astrophysics Data System (ADS)

    Chen, Jin-Syung Fred

    The mechanism of stress corrosion cracking (SCC) of Cu-30Au in 0.6 M NaCl was investigated by a series of experiments, in which samples were dealloyed (i.e., selective removal of copper atoms) by potentiostatic anodic polarization at zero applied stress (i) for varying lengths of time (10 seconds to 30 minutes) and then impact bent, and (ii) for 30 minutes followed by a period of time (5 seconds to 10 minutes) at the open circuit potential and then impact bent. The results indicate that dealloying at zero applied stress produces a surface porous layer that is capable, for a brief period of time (<= ~ 15 seconds), of inducing intergranular cleavage failure of the normally ductile FCC substrate. However, for time >15 seconds at open circuit potential, aging or coarsening reverses the ability of the surface layer to induce cleavage. In addition, samples were dealloyed and simultaneously stressed at various nominal values. At low values of applied stress, failure occurred by brittle intergranular cracking (IGSCC); and at high values of stress, failure occurred by brittle transgranular cracking (TGSCC). The results indicate that the mechanism of IGSCC is identical to that of TGSCC and can best be described by a modification of the "film-induced cleavage" model. The implication of the aging phenomenon to the film-induced cleavage model of stress corrosion cracking is also discussed. An electrochemical scanning tunneling microscope (ESTM) was built and used to study the in-situ dealloying process of thin-film Cu-Au alloys. Thin-films of Cu-75 at%Au alloy were prepared by thermal evaporation of the bulk alloy and deposition of the vapor onto heated mica. The surface structure of the thin film thus grown consists of terrace of well defined (111) planes separated by atomic height steps. The results from in-situ ESTM indicate that if applied potentials were lower than the critical potential (E_{rm c}), dissolution of Cu preferentially occurred at the low coordination sites

  3. Scanning electrochemical microscopy of DNA hybridization on DNA microarrays enhanced by HRP-modified SiO2 nanoparticles.

    PubMed

    Fan, Huajun; Wang, Xiaolan; Jiao, Fang; Zhang, Fan; Wang, Qingjiang; He, Pingang; Fang, Yuzhi

    2013-07-02

    Imaging of localized hybridization of nucleic acids immobilized on a glass DNA microarray was performed by means of generation collection (GC) mode scanning electrochemical microscopy (SECM). Amine-tethered oligodeoxynucleotide probes, spotted on the glass surface, were hybridized with an unmodified target sequence and a biotinylated indicator probe via sandwich hybridization. Spots where sequence-specific hybridization had occurred were modified by streptavidin-horseradish-peroxidase-(HRP)-wrapped SiO2 nanoparticles through the biotin-streptavidin interaction. In the presence of H2O2, hydroquinone (H2Q) was oxidized to benzoquinone (BQ) at the modified spot surface through the HRP catalytic reaction, and the generated BQ corresponding to the amount of target DNA was reduced in solution by an SECM tip. With this DNA microarray, a number of genes could be detected simultaneously and selectively enough to discriminate between complementary sequences and those containing base mismatches. The DNA targets at prepared spots could be imaged in SECM GC mode over a wide concentration range (10(-7)-10(-12) M). This technique may find applications in genomic sequencing.

  4. Scanning electrochemical microscopy based evaluation of influence of pH on bioelectrochemical activity of yeast cells - Saccharomyces cerevisiae.

    PubMed

    Ramanavicius, A; Morkvenaite-Vilkonciene, I; Kisieliute, A; Petroniene, J; Ramanaviciene, A

    2017-01-01

    In this research scanning electrochemical microscopy was applied for the investigation of immobilized yeast Saccharomyces cerevisiae cells. Two redox mediators based system was applied in order to increase the efficiency of charge transfer from yeast cells. 9,10-phenanthrenequinone (PQ) was applied as a lipophilic redox mediator, which has the ability to cross the cell's membrane; another redox mediator was ferricyanide, which acted as a hydrophylic electron acceptor able to transfer electrons from the PQ to the working electrode of SECM. Hill's function was applied to determine the optimal pH for this described SECM-based system. The influence of pH on cell viability could be well described by Hill's function. It was determined that at pH 6.5 the PQ has a minimal toxic influence on yeast cells, and the kinetics of metabolic processes in cells as well as electron transfer rate achieved in consecutive action of both redox mediators were appropriate to achieve optimal current signals.

  5. Electrochemical strain microscopy time spectroscopy: Model and experiment on LiMn{sub 2}O{sub 4}

    SciTech Connect

    Amanieu, Hugues-Yanis; Thai, Huy N. M. Schröder, Jörg; Luchkin, Sergey Yu.; Rosato, Daniele; Lupascu, Doru C.; Keip, Marc-André; Kholkin, Andrei L.

    2015-08-07

    Electrochemical Strain Microscopy (ESM) can provide useful information on ionic diffusion in solids at the local scale. In this work, a finite element model of ESM measurements was developed and applied to commercial lithium manganese (III,IV) oxide (LiMn{sub 2}O{sub 4}) particles. ESM time spectroscopy was used, where a direct current (DC) voltage pulse locally disturbs the spatial distribution of mobile ions. After the pulse is off, the ions return to equilibrium at a rate which depends on the Li diffusivity in the material. At each stage, Li diffusivity is monitored by measuring the ESM response to a small alternative current (AC) voltage simultaneously applied to the tip. The model separates two different mechanisms, one linked to the response to DC bias and another one related to the AC excitation. It is argued that the second one is not diffusion-driven but is rather a contribution of the sum of several mechanisms with at least one depending on the lithium ion concentration explaining the relaxation process. With proper fitting of this decay, diffusion coefficients of lithium hosts could be extracted. Additionally, the effect of phase transition in LiMn{sub 2}O{sub 4} is taken into account, explaining some experimental observations.

  6. Using scanning electrochemical microscopy to probe chemistry at the solid-liquid interface in chemically amplified immersion lithography

    NASA Astrophysics Data System (ADS)

    LeSuer, Robert J.; Fan, Fu-Ren F.; Bard, Allen J.; Taylor, J. Christopher; Tsiartas, Pavlos; Willson, Grant; Conley, Willard E.; Feit, Gene; Kunz, Roderick R.

    2004-05-01

    Three modes of scanning electrochemical microscopy (SECM) - voltammetry, pH, and conductivity - have been used to better understand the chemistry at, and diffusion through, the solid/liquid interface formed between a resist film and water in 193 nm immersion lithography. Emphasis has been placed on investigating the photoacid generator (PAG), triphenylsulfonium perfluorobutanesulfonate, and the corresponding photoacid. The reduction of triphenylsulfonium at a hemispherical Hg microelectrode was monitored using square wave voltammetry to detect trace amounts of the PAG leaching from the surface. pH measurements at a 100 μm diameter Sb microelectrode show the formation of acid in the water layer above a resist upon exposure with UV irradiation. Bipolar conductance measurements at a 100 μm Pt tip positioned 100 μm from the surface indicate that the conductivity of the solution during illumination is dependent upon the percentage of PAG in the film. Liquid chromatography mass spectrometric analysis of water samples in contact with resist films has been used to quantify the amounts (< 10 ng/cm2) of PAG leaching from the film in the dark which occurs within the first 30 seconds of contact time. Washing the film removes approximately 80% of the total leachable PAG.

  7. Investigating catalase activity through hydrogen peroxide decomposition by bacteria biofilms in real time using scanning electrochemical microscopy.

    PubMed

    Abucayon, Erwin; Ke, Neng; Cornut, Renaud; Patelunas, Anthony; Miller, Douglas; Nishiguchi, Michele K; Zoski, Cynthia G

    2014-01-07

    Catalase activity through hydrogen peroxide decomposition in a 1 mM bulk solution above Vibrio fischeri (γ-Protebacteria-Vibrionaceae) bacterial biofilms of either symbiotic or free-living strains was studied in real time by scanning electrochemical microscopy (SECM). The catalase activity, in units of micromoles hydrogen peroxide decomposed per minute over a period of 348 s, was found to vary with incubation time of each biofilm in correlation with the corresponding growth curve of bacteria in liquid culture. Average catalase activity for the same incubation times ranging from 1 to 12 h was found to be 0.28 ± 0.07 μmol H2O2/min for the symbiotic biofilms and 0.31 ± 0.07 μmol H2O2/min for the free-living biofilms, suggesting similar catalase activity. Calculations based on Comsol Multiphysics simulations in fitting experimental biofilm data indicated that approximately (3 ± 1) × 10(6) molecules of hydrogen peroxide were decomposed by a single bacterium per second, signifying the presence of a highly active catalase. A 2-fold enhancement in catalase activity was found for both free-living and symbiotic biofilms in response to external hydrogen peroxide concentrations as low as 1 nM in the growth media, implying a similar mechanism in responding to oxidative stress.

  8. Giant Electric-Field-Induced Strain in PVDF-Based Battery Separator Membranes Probed by Electrochemical Strain Microscopy.

    PubMed

    Romanyuk, Konstantin; Costa, Carlos M; Luchkin, Sergey Yu; Kholkin, Andrei L; Lanceros-Méndez, Senentxu

    2016-05-31

    Efficiency of lithium-ion batteries largely relies on the performance of battery separator membrane as it controls the mobility and concentration of Li-ions between the anode and cathode electrodes. Recent advances in electrochemical strain microscopy (ESM) prompted the study of Li diffusion and transport at the nanoscale via electromechanical strain developed under an application of inhomogeneous electric field applied via the sharp ESM tip. In this work, we observed unexpectedly high electromechanical strain developed in polymer membranes based on porous poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) and, using it, could study a dynamics of electroosmotic flow of electrolyte inside the pores. We show that, independently of the separator membrane, electric field-induced deformation observed by ESM on wetted membrane surfaces can reach up to 10 nm under a moderate bias of 1 V (i.e., more than an order of magnitude higher than that in best piezoceramics). Such a high strain is explained by the electroosmotic flow in a porous media composed of PVDF. It is shown that the strain-based ESM method can be used to extract valuable information such as average pore size, porosity, elasticity of membrane in electrolyte solvent, and membrane-electrolyte affinity expressed in terms of zeta potential. Besides, such systems can, in principle, serve as actuators even in the absence of apparent piezoelectricity in amorphous PVDF.

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

    PubMed

    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.

  10. Cyclic Voltammetry Probe Approach Curves with Alkali Amalgams at Mercury Sphere-Cap Scanning Electrochemical Microscopy Probes.

    PubMed

    Barton, Zachary J; Rodríguez-López, Joaquín

    2017-03-07

    We report a method of precisely positioning a Hg-based ultramicroelectrode (UME) for scanning electrochemical microscopy (SECM) investigations of any substrate. Hg-based probes are capable of performing amalgamation reactions with metal cations, which avoid unwanted side reactions and positive feedback mechanisms that can prove problematic for traditional probe positioning methods. However, prolonged collection of ions eventually leads to saturation of the amalgam accompanied by irreversible loss of Hg. In order to obtain negative feedback positioning control without risking damage to the SECM probe, we implement cyclic voltammetry probe approach surfaces (CV-PASs), consisting of CVs performed between incremental motor movements. The amalgamation current, peak stripping current, and integrated stripping charge extracted from a shared CV-PAS give three distinct probe approach curves (CV-PACs), which can be used to determine the tip-substrate gap to within 1% of the probe radius. Using finite element simulations, we establish a new protocol for fitting any CV-PAC and demonstrate its validity with experimental results for sodium and potassium ions in propylene carbonate by obtaining over 3 orders of magnitude greater accuracy and more than 20-fold greater precision than existing methods. Considering the timescales of diffusion and amalgam saturation, we also present limiting conditions for obtaining and fitting CV-PAC data. The ion-specific signals isolated in CV-PACs allow precise and accurate positioning of Hg-based SECM probes over any sample and enable the deployment of CV-PAS SECM as an analytical tool for traditionally challenging conditions.

  11. Mapping Cd²⁺-induced membrane permeability changes of single live cells by means of scanning electrochemical microscopy.

    PubMed

    Filice, Fraser P; Li, Michelle S M; Henderson, Jeffrey D; Ding, Zhifeng

    2016-02-18

    Scanning Electrochemical Microscopy (SECM) is a powerful, non-invasive, analytical methodology that can be used to investigate live cell membrane permeability. Depth scan SECM imaging allowed for the generation of 2D current maps of live cells relative to electrode position in the x-z or y-z plane. Depending on resolution, one depth scan image can contain hundreds of probe approach curves (PACs). Individual PACs were obtained by simply extracting vertical cross-sections from the 2D image. These experimental PACs were overlaid onto theoretically generated PACs simulated at specific geometry conditions. Simulations were carried out using 3D models in COMSOL Multiphysics to determine the cell membrane permeability coefficients at different locations on the surface of the cells. Common in literature, theoretical PACs are generated using a 2D axially symmetric geometry. This saves on both compute time and memory utilization. However, due to symmetry limitations of the model, only one experimental PAC right above the cell can be matched with simulated PAC data. Full 3D models in this article were developed for the SECM system of live cells, allowing all experimental PACs over the entire cell to become usable. Cd(2+)-induced membrane permeability changes of single human bladder (T24) cells were investigated at several positions above the cell, displaced from the central axis. The experimental T24 cells under study were incubated with Cd(2+) in varying concentrations. It is experimentally observed that 50 and 100 μM Cd(2+) caused a decrease in membrane permeability, which was uniform across all locations over the cell regardless of Cd(2+) concentration. The Cd(2+) was found to have detrimental effects on the cell, with cells shrinking in size and volume, and the membrane permeability decreasing. A mapping technique for the analysis of the cell membrane permeability under the Cd(2+) stress is realized by the methodology presented.

  12. Photoelectrochemical and Electrochemical Characterization of Sub-Micro-Gram Amounts of Organic Semiconductors Using Scanning Droplet Cell Microscopy

    PubMed Central

    2014-01-01

    A model organic semiconductor (MDMO-PPV) was used for testing a modified version of a photoelectrochemical scanning droplet cell microscope (PE-SDCM) adapted for use with nonaqueous electrolytes and containing an optical fiber for localized illumination. The most attractive features of the PE-SDCM are represented by the possibility of addressing small areas on the investigated substrate and the need of small amounts of electrolyte. A very small amount (ng) of the material under study is sufficient for a complete electrochemical and photoelectrochemical characterization due to the scanning capability of the cell. The electrochemical behavior of the polymer was studied in detail using potentiostatic and potentiodynamic investigations as well as electrochemical impedance spectroscopy. Additionally, the photoelectrochemical properties were investigated under illumination conditions, and the photocurrents found were at least 3 orders of magnitude higher than the dark (background) current, revealing the usefulness of this compact microcell for photovoltaic characterizations. PMID:25101149

  13. Scanning electrochemical microscopy study of ion annihilation electrogenerated chemiluminescence of rubrene and [Ru(bpy)3]2+.

    PubMed

    Rodríguez-López, Joaquín; Shen, Mei; Nepomnyashchii, Alexander B; Bard, Allen J

    2012-06-06

    Scanning electrochemical microscopy (SECM) was used for the study of electrogenerated chemiluminescence (ECL) in the radical annihilation mode. The concurrent steady-state generation of radical ions in the microgap formed between a SECM probe and a transparent microsubstrate provides a distance-dependent ECL signal that can provide information about the kinetics, stability, and mechanism of the light emission process. In the present study, the ECL emission from rubrene and [Ru(bpy)(3)](2+) was used to model the system by carrying out experiments with the SECM and light-detecting apparatus inside an inert atmosphere box. We studied the influence of the distance between the two electrodes, d, and the annihilation kinetics on the ECL light emission profiles under steady-state conditions, as well as the ECL profiles when carrying out cyclic voltammetry (CV) at a fixed d. Experimental results are compared to simulated results obtained through commercial finite element method software. The light produced by annihilation of the ions was a function of d; stronger light was observed at smaller d. The distance dependence of the ECL emission allows the construction of light approach curves in a similar fashion as with the tip currents in the feedback mode of SECM. These ECL approach curves provide an additional channel to describe the reaction kinetics that lead to ECL; good agreement was found between the ECL approach curve emission profile and the simulated results for a fast, diffusion-limited second-order annihilation process (k(ann) > 10(7) M(-1) s(-1)). In the CV mode at fixed distance, the ECL emission of rubrene showed two distinct signals at different potentials when fixing the substrate to generate the radical cation and scanning the tip to generate the radical anion. The first signal (pre-emission) corresponded to an emission well before reaching the generation of the radical anion and was more intense on Au than on Pt. The second ECL signal showed the expected

  14. Scanning Electrochemical Microscopy for the Investigation of Galvanic Corrosion of Iron with Zinc in 0.1 M NaCl Solution

    NASA Astrophysics Data System (ADS)

    Joseph Raj, X.; Nishimura, T.

    2016-02-01

    Scanning electrochemical microscopy was used to monitor microscopic aspects of the electrochemical processes at the iron-zinc couple immersed in 0.1 M NaCl aqueous solution. The SECM measured the concentration of chemical species relevant to the corrosion processes. The electrochemical behavior of galvanic Fe/Zn coupling was investigated as a function of time using SECM microelectrode both as Fe/Zn joined together as well as away from each other. SECM amperometric line scan curves were obtained over the Fe/Zn at a constant distance. In the first case, the chemical species participating in the corrosion reactions at the sample are detected at the SECM tip by applying appropriate potential values to the microelectrode. The release of Zn2+ ionic species into the solution phase from local anodic sites, as well as the consumption of dissolved oxygen at the corresponding cathodic locations, was successfully monitored. The results revealed that the galvanic couple where Fe/Zn is close to each other will show higher corrosion rate of zinc than that of galvanic couple away from each other. The Fe/Zn couple away from each other showed a decrease in current values with time. This is due to the formation of oxide layer of Zn over the Fe followed by the protection of the corrosion products with further exposure times.

  15. Characterization of local electrochemical doping of high performance conjugated polymer for photovoltaics using scanning droplet cell microscopy.

    PubMed

    Gasiorowski, Jacek; Mardare, Andrei Ionut; Sariciftci, Niyazi Serdar; Hassel, Achim Walter

    2013-12-15

    The electrochemical oxidation of a next generation low bandgap high performance photovoltaic material namely poly[4,8-bis-substituted-benzo[1,2-b:4,5-b0]dithiophene-2,6-diyl-alt-4-substituted-thieno[3,4-b] thiophene-2,6-diyl] (PBDTTT-c) thin film was investigated using a scanning droplet cell microscope. Cyclic voltammetry was used for the basic characterization of the oxidation/doping of PBDTTT-c. Application of the different final potentials during the electrochemical study provides a close look to the oxidation kinetics. The electrical properties of both doped and undoped PBDTTT-c were analyzed in situ by electrochemical impedance spectroscopy giving the possibility to correlate the changes in the doping level with the subsequent changes in the resistance and capacitance. As a result one oxidation peak was found during the cyclic voltammetry and in potentiostatic measurements. From Mott-Schottky analysis a donor concentration of 2.3 × 10(20) cm(-3) and a flat band potential of 1.00 V vs. SHE were found. The oxidation process resulted in an increase of the conductivity by two orders of magnitude reaching a maximum for the oxidized form of 1.4 S cm(-1).

  16. Insights into electrode/electrolyte interfacial processes and the effect of nanostructured cobalt oxides loading on graphene-based hybrids by scanning electrochemical microscopy

    NASA Astrophysics Data System (ADS)

    Gupta, Sanju; Carrizosa, Sara B.

    2016-12-01

    Nanostructured cobalt oxide polymorphs (CoO and Co3O4) deposited via electrodeposition allowed optimal loading on supercapacitive graphene nanosheets producing a set of graphene-based hybrids namely, CoO/GO, CoO/ErGO, Co3O4/GO, Co3O4/rGO, and Co3O4/ErGO, as pseudocapacitive electrochemical electrodes. We gained fundamental insights into the complex physicochemical interfacial processes at electrode surfaces and electrode/electrolyte (or solid/liquid) interfaces by scanning electrochemical microscopy operating in the feedback probe approach and imaging modes while monitoring and mapping the redox probe (re)activity behavior. We determined the various experimental descriptors including diffusion coefficient, electron transfer rate, and electroactive site distribution on electrodes. We emphasize the interplay of (1) heterogeneous basal and edge plane active sites, (2) graphene surface functional moieties (conducting/semiconducting), and (3) crystalline spinel cobalt oxides (semiconducting/insulating) coated graphene, reinforcing the available electron density of states in the vicinity of the Fermi level contributing to higher electroactivity, faster interfacial diffusion, and shorter distances for electron transfer, facilitated through molecular and chemical bridges obtained by electrodeposition as compared with the physical deposition.

  17. Potential-dependent structures investigated at the perchloric acid solution/iodine modified Au(111) interface by electrochemical frequency-modulation atomic force microscopy.

    PubMed

    Utsunomiya, Toru; Tatsumi, Shoko; Yokota, Yasuyuki; Fukui, Ken-ichi

    2015-05-21

    Electrochemical frequency-modulation atomic force microscopy (EC-FM-AFM) was adopted to analyze the electrified interface between an iodine modified Au(111) and a perchloric acid solution. Atomic resolution imaging of the electrode was strongly dependent on the electrode potential within the electrochemical window: each iodine atom was imaged in the cathodic range of the electrode potential, but not in the more anodic range where the tip is retracted by approximately 0.1 nm compared to the cathodic case for the same imaging parameters. The frequency shift versus tip-to-sample distance curves obtained in the electric double layer region on the iodine adlayer indicated that the water structuring became weaker at the anodic potential, where the atomic resolution images could not be obtained, and immediately recovered at the original cathodic potential. The reversible hydration structures were consistent with the reversible topographic images and the cyclic voltammetry results. These results indicate that perchlorate anions concentrated at the anodic potential affect the interface hydration without any irreversible changes to the interface under these conditions.

  18. Comparative electrochemical scanning tunneling microscopy study of nonionic fluorosurfactant zonyl FSN self-assembled monolayers on Au(111) and Au(100): a potential-induced structural transition.

    PubMed

    Tang, Yongan; Yan, Jiawei; Zhu, Feng; Sun, Chunfeng; Mao, Bingwei

    2011-02-01

    We investigate the structure of nonionic fluorosurfactant zonyl FSN self-assembled monolayers on Au(111) and Au(100) in 0.05 M H(2)SO(4) as a function of the electrode potential by electrochemical scanning tunneling microscopy (ECSTM). On Au(111), a (3(1/2) × 3(1/2))R30° arrangement of the FSN SAMs is observed, which remains unchanged in the potential range where the redox reaction of FSN molecules does not occur. On Au(100), some parallel corrugations of the FSN SAMs are observed, which originate from the smaller distance and the repulsive interaction between FSN molecules to make the FSN molecules deviate from the bridging sites, and ECSTM reveals a potential-induced structural transition of the FSN SAMs. The experimental observations are rationalized by the effect of the intermolecular interaction. The smaller distance between molecules on Au(100) results in the repulsive force, which increases the probability of structural change induced by external factors (i.e., the electrode potential). The appropriate distance and interactions of FSN molecules account for the stable structure of FSN SAMs on Au(111). Surface crystallography may influence the intermolecular interaction through changing the molecular arrangements of the SAMs. The results benefit the molecular-scale understanding of the behavior of the FSN SAMs under electrochemical potential control.

  19. Electropolishing of stainless steels in a choline chloride based ionic liquid: an electrochemical study with surface characterisation using SEM and atomic force microscopy.

    PubMed

    Abbott, Andrew P; Capper, Glen; McKenzie, Katy J; Glidle, Andrew; Ryder, Karl S

    2006-09-28

    We have studied the anodic dissolution (electropolishing) of various stainless steel alloys in an ionic liquid comprising a 2 : 1 stoichiometric mix of ethylene glycol (EG) and choline chloride. We have used a combination of electrochemical and spectroscopic methods together with in situ liquid probe microscopy. We discuss the role and influence of the surface oxide passivation layer, characterized here by X-ray photoelectron spectroscopy (XPS) and linear sweep voltammetry, on the polishing process. We address the question of dealloying during the polish in order to contribute to our understanding of the viability of the ionic liquid as a replacement industrial electropolishing medium; the current commercial process uses a corrosive mixture of phosphoric and sulfuric acids. Also, we present data from ex situ and in situ liquid AFM studies giving both a qualitative and quantitative insight into the nature and scale of morphological changes at the steel surface during the polishing process.

  20. Scanning electrochemical cell microscopy: theory and experiment for quantitative high resolution spatially-resolved voltammetry and simultaneous ion-conductance measurements.

    PubMed

    Snowden, Michael E; Güell, Aleix G; Lai, Stanley C S; McKelvey, Kim; Ebejer, Neil; O'Connell, Michael A; Colburn, Alexander W; Unwin, Patrick R

    2012-03-06

    Scanning electrochemical cell microscopy (SECCM) is a high resolution electrochemical scanning probe technique that employs a dual-barrel theta pipet probe containing electrolyte solution and quasi-reference counter electrodes (QRCE) in each barrel. A thin layer of electrolyte protruding from the tip of the pipet ensures that a gentle meniscus contact is made with a substrate surface, which defines the active surface area of an electrochemical cell. The substrate can be an electrical conductor, semiconductor, or insulator. The main focus here is on the general case where the substrate is a working electrode, and both ion-conductance measurements between the QRCEs in the two barrels and voltammetric/amperometric measurements at the substrate can be made simultaneously. In usual practice, a small perpendicular oscillation of the probe with respect to the substrate is employed, so that an alternating conductance current (ac) develops, due to the change in the dimensions of the electrolyte contact (and hence resistance), as well as the direct conductance current (dc). It is shown that the dc current can be predicted for a fixed probe by solving the Nernst-Planck equation and that the ac response can also be derived from this response. Both responses are shown to agree well with experiment. It is found that the pipet geometry plays an important role in controlling the dc conductance current and that this is easily measured by microscopy. A key feature of SECCM is that mass transport to the substrate surface is by diffusion and, for charged analytes, ion migration which can be controlled and varied quantifiably via the bias between the two QRCEs. For a working electrode substrate this means that charged redox-active analytes can be transported to the electrode/solution interface in a well-defined and controllable manner and that relatively fast heterogeneous electron transfer kinetics can be studied. The factors controlling the voltammetric response are determined by

  1. Ion permeability of the nuclear pore complex and ion-induced macromolecular permeation as studied by scanning electrochemical and fluorescence microscopy.

    PubMed

    Kim, Jiyeon; Izadyar, Anahita; Shen, Mei; Ishimatsu, Ryoichi; Amemiya, Shigeru

    2014-02-18

    Efficient delivery of therapeutic macromolecules and nanomaterials into the nucleus is imperative for gene therapy and nanomedicine. Nucleocytoplasmic molecular transport, however, is tightly regulated by the nuclear pore complex (NPC) with the hydrophobic transport barriers based on phenylalanine and glycine repeats. Herein, we apply scanning electrochemical microscopy (SECM) to quantitatively study the permeability of the NPCs to small probe ions with a wide range of hydrophobicity as a measure of their hydrophobic interactions with the transport barriers. Amperometric detection of the redox-inactive probe ions is enabled by using the ion-selective SECM tips based on the micropipet- or nanopipet-supported interfaces between two immiscible electrolyte solutions. The remarkably high ion permeability of the NPCs is successfully measured by SECM and theoretically analyzed. This analysis demonstrates that the ion permeability of the NPCs is determined by the dimensions and density of the nanopores without a significant effect of the transport barriers on the transported ions. Importantly, the weak ion-barrier interactions become significant at sufficiently high concentrations of extremely hydrophobic ions, i.e., tetraphenylarsonium and perfluorobutylsulfonate, to permeabilize the NPCs to naturally impermeable macromolecules. Dependence of ion-induced permeabilization of the NPC on the pathway and mode of macromolecular transport is studied by using fluorescence microscopy to obtain deeper insights into the gating mechanism of the NPC as the basis of a new transport model.

  2. Measurement of apparent diffusion coefficients within ultrathin nafion Langmuir-Schaefer films: comparison of a novel scanning electrochemical microscopy approach with cyclic voltammetry.

    PubMed

    Bertoncello, Paolo; Ciani, Ilenia; Li, Fei; Unwin, Patrick R

    2006-12-05

    The use of scanning electrochemical microscopy (SECM) to evaluate the apparent diffusion coefficient, Dapp, of redox-active species in ultrathin Nafion films is described. In this technique, an ultramicroelectrode (UME) tip, positioned close to a film on a macroscopic electrode, is used to oxidize (or reduce) a species in bulk solution, causing the tip-generated oxidant (reductant) to diffuse to the film/solution interface. The oxidation (reduction) of film-confined species regenerates the reductant (oxidant) in solution, leading to feedback to the UME. A numerical model is developed that allows Dapp to be determined. For these studies, ultrathin films of Nafion were prepared using the Langmuir-Schaefer (LS) technique and loaded with an electroactive species, either the ferrocene derivative ferrocenyltrimethylammonium cation, FA+, or tris(2,2'-bipyridyl)ruthenium(II), Ru(bpy)32+. The morphology and the thickness of the Nafion LS films (1.5 +/- 0.2 nm per layer deposited) were evaluated using atomic force microscopy (AFM). For comparison with the SECM measurements, cyclic voltammetry (CV) was employed to evaluate the concentration of electroactive species within the Nafion LS films and to determine Dapp. The latter was found to be essentially invariant with film thickness, but the value for Ru(bpy)32+ was 1 order of magnitude larger than for FA+. CV and SECM measurements yield different values of Dapp, and the underlying reasons are discussed. In general, the Dapp values for these films are considerably smaller than for recast Nafion films, which can be attributed to the compactness of Nafion LS films. Nonetheless, the ultrathin nature of the films leads to fast response times, and we thus expect that these modified electrodes could find applications in sensing, electroanalysis, and electrocatalysis.

  3. Ordered molecular assemblies of substituted bis(phthalocyaninato) rare earth complexes on Au(111): in situ scanning tunneling microscopy and electrochemical studies.

    PubMed

    Ma, Houyi; Yang, Liang-Yueh Ou; Pan, Na; Yau, Shueh-Lin; Jiang, Jianzhuang; Itaya, Kingo

    2006-02-28

    Substituted bis(phthalocyaninato) rare earth complexes ML2 (M = Y and Ce; L = [Pc(OC8H17)8]2, where Pc = phthalocyaninato) were adsorbed onto single crystalline Au(111) electrodes from benzene saturated with either YL2 or CeL2 complex at room temperature. In situ scanning tunneling microscopy (STM) and cyclic voltammetry (CV) were used to examine the structures and the redox reactions of these admolecules on Au(111) electrodes in 0.1 mol dm(-3) HClO4. The CVs obtained with YL2- and CeL2-coated Au(111) electrodes respectively contained two and three pairs of redox peaks between 0 and 1.0 V (versus reversible hydrogen electrode). STM molecular resolution revealed that YL2 and CeL2 admolecules were imaged as spherical protrusions separated by 2.3 nm, which suggests that they were oriented with their molecular planes parallel to the unreconstructed Au(111)-(1 x 1). Both molecules when adsorbing from approximately micromolar benzene dosing solutions produced mainly ordered arrays characterized as (8 x 5 radical3)rect (theta = 0.0125). The redox reactions occurring between 0.2 and 1.0 V caused no change in the adlayer, but they were desorbed or oxidized at the negative and positive potential limits. The processes of adsorption and desorption at the negative potentials were reversible to the modulation of potential. Electrochemical impedance spectroscopy (EIS) and CV measurements showed that YL2 and CeL2 adlayers could block the adsorption of perchlorate anions and mediating electron transfer at the Au(111) electrode, leading to the enhancement of charge transfer for the ferro/ferricyanide redox couple.

  4. The geometry of nanometer-sized electrodes and its influence on electrolytic currents and metal deposition processes in scanning tunneling and scanning electrochemical microscopy

    NASA Astrophysics Data System (ADS)

    Sklyar, Oleg; Treutler, Thomas H.; Vlachopoulos, Nikolaos; Wittstock, Gunther

    2005-12-01

    Electrodes with an effective radius of about 10 nm have been produced by a combination of electrochemical etching, electrophoretic deposition of polymer, and heat curing. Their size and stability were characterized by cyclic voltammetry. They were then used in combined electrochemical scanning tunneling microscopic (ECSTM) and scanning electrochemical microscopic (SECM) experiments. In an extension of an earlier report, electrochemical surface modification approaches are reported here. They comprise the local electrochemical removal of a self-assembled monolayer (SAM) of dodecanethiol on flame-annealed gold by an electrochemical desorption procedure. The possibility of local electrochemical deposition is demonstrated by positioning a nanoelectrode 0.5 nm above a surface and switching off the distance regulation while performing an electrodeposition of Pt at the tip. The growing deposit bridges the tip-sample gap. If the distance regulation is switched on after 1 ms, the Pt junction is disrupted leaving a Pt nanodot at the sample surface. The dot was characterized by ECSTM experiments after solution exchange. Digital simulations by the boundary element method (BEM) provide a quantitative description of Faraday currents in nanoelectrochemical assemblies. A software tool was created that can accept arbitrary geometries as input data sets. The flexibility of the simulation strategy was demonstrated by the calculation of local current densities during electrochemical copper deposition on a smooth electrode in the presence of an ECSTM tip close to the surface. The current densities deviate less than 1% from those in the absence of tip if the average current density is kept below 1 μA cm -2. SECM approach curves for nanoelectrodes were also calculated.

  5. Analytical and mineralogical studies of ore and impurities from a chromite mineral using X-ray analysis, electrochemical and microscopy techniques.

    PubMed

    Sánchez-Ramos, S; Doménech-Carbó, A; Gimeno-Adelantado, J V; Peris-Vicente, J

    2008-02-15

    A wide analytical study of South African chromite ore, material with high interest in ceramic industry, has been carried out. With this purpose, an accurate chemical identification and mineralogical characterization of the mineral and the gangue have been performed using X-ray fluorescence (XRF), voltammetry, X-ray diffraction (XRD), light microscopy (LM), and scanning electron microscopy (SEM/EDX). The elemental composition of the sample (ore and gangue) has been obtained by XRF. The voltammetric analysis has allowed to demonstrate that iron in the sample was as Fe(II). The main compound of the chromite ore was a spinel (magnesiochromite ferroan), identified by XRD from the sample, which constitutes the chromite ore. This technique has also been useful to characterize some silicates as impurities in the chromite ore sample. Light microscopy has allowed the detection of the spinel and the identification of a silicate impurity (chrome chlorite), by means of their colouration. On the other hand, the other silicate impurity was identified as labradorite by means of X-ray microscopy by SEM/EDX. Finally, a strategy was developed to calculate the composition of each mineral in the unknown sample. The obtained results were: chromite spinel 82.89%, chlorite 12.79% and labradorite 4.32%.

  6. High-Speed Electrochemical Imaging.

    PubMed

    Momotenko, Dmitry; Byers, Joshua C; McKelvey, Kim; Kang, Minkyung; Unwin, Patrick R

    2015-09-22

    The design, development, and application of high-speed scanning electrochemical probe microscopy is reported. The approach allows the acquisition of a series of high-resolution images (typically 1000 pixels μm(-2)) at rates approaching 4 seconds per frame, while collecting up to 8000 image pixels per second, about 1000 times faster than typical imaging speeds used up to now. The focus is on scanning electrochemical cell microscopy (SECCM), but the principles and practicalities are applicable to many electrochemical imaging methods. The versatility of the high-speed scan concept is demonstrated at a variety of substrates, including imaging the electroactivity of a patterned self-assembled monolayer on gold, visualization of chemical reactions occurring at single wall carbon nanotubes, and probing nanoscale electrocatalysts for water splitting. These studies provide movies of spatial variations of electrochemical fluxes as a function of potential and a platform for the further development of high speed scanning with other electrochemical imaging techniques.

  7. Probing the conformation and 2D-distribution of pyrene-terminated redox-labeled poly(ethylene glycol) chains end-adsorbed on HOPG using cyclic voltammetry and atomic force electrochemical microscopy.

    PubMed

    Anne, Agnès; Bahri, Mohamed Ali; Chovin, Arnaud; Demaille, Christophe; Taofifenua, Cécilia

    2014-03-14

    The present paper aims at illustrating how end-attachment of water-soluble flexible chains bearing a terminal functional group onto graphene-like surfaces has to be carefully tuned to ensure the proper positioning of the functional moiety with respect to the anchoring surface. The model experimental system considered here consists of a layer of poly(ethylene glycol) (PEG) chains, bearing an adsorbing pyrene foot and a ferrocene (Fc) redox functional head, self-assembled onto highly oriented pyrolytic graphite (HOPG). Cyclic voltammetry is used to accurately measure the chain coverage and gain insights into the microenvironment experienced by the Fc heads. Molecule-touching atomic force electrochemical microscopy (Mt/AFM-SECM) is used to simultaneously probe the chain conformation and the position of the Fc heads within the layer, and also to map the 2D-distribution of the chains over the surface. This multiscale electrochemical approach allows us to show that whereas Fc-PEG-pyrene readily self-assembles to form extremely homogeneous layers, the strongly hydrophobic nature of graphite planes results in a complex coverage-dependent structure of the PEG layer due to the interaction of the ferrocene label with the HOPG surface. It is shown that, even though pyrene is known to adsorb particularly strongly onto HOPG, the more weakly adsorbing terminal ferrocene can also act as the chain anchoring moiety especially at low coverage. However we show that beyond a critical coverage value the Fc-PEG-pyrene chains adopt an ideal "foot-on" end-attached conformation allowing the Fc head to explore a volume away from the surface solely limited by the PEG chain elasticity.

  8. Temperature-dependent Li-ion diffusion and Activation Energy of Li1.2Co0.13Ni0.13Mn0.54O2 thin film cathode at Nanoscale by using Electrochemical Strain Microscopy.

    PubMed

    Yang, Shan; Yan, Binggong; Wu, Jiaxiong; Lu, Li; Zeng, Kaiyang

    2017-04-07

    This paper presents the in situ mapping of temperature-dependent lithium ions diffusion at nanometer level in thin film Li1.2Co0.13Ni0.13Mn0.54O2 cathode using Electrochemical Strain Microscopy (ESM). Thin film Li1.2Co0.13Ni0.13Mn0.54O2 cathode exhibits higher Li-ions diffusivities with increasing the temperature, which explains the higher capacity ob-served in the Li-ion batteries with Li-rich cathode at elevated temperature. In addition, the activation energy for lithi-um ions diffusion can be extracted in an Arrhenius-type plot at the level of grain structure with the assumption that the ionic movement is diffusion controlled. Compared with the grain interiors, the grain boundaries show relatively lower activation energy hence it is preferred diffusion path for Li-ions. This study has bridged the gap between atomis-tic calculations and traditional macroscopic experiments, showing the direct evidence as well as the mechanisms for ionic diffusion for Li-rich cathode material.

  9. Detection of the Sn(III) intermediate and the mechanism of the Sn(IV)/Sn(II) electroreduction reaction in bromide media by cyclic voltammetry and scanning electrochemical microscopy.

    PubMed

    Chang, Jinho; Bard, Allen J

    2014-01-08

    Fast-scan cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM) were used to investigate the reduction of Sn(IV) as the hexabromo complex ion in a 2 M HBr-4 M NaBr medium. CV at scan rates to 100 V/s and SECM indicated the reaction pathway involves ligand-coupled electron transfer via an ECEC-DISP process: (1) one-electron reduction of Sn(IV)Br6(2-) to Sn(III)Br6(3-); (2) bromide dissociation of the reduced Sn(III)Br6(3-) to Sn(III)Br5(2-); (3) disproportionation of the reduced 2Sn(III)Br5(2-) to Sn(IV)Br5(-) and Sn(II)Br5(3-); (4) one-electron reduction of Sn(III)Br5(2-) to Sn(II)Br5(3-); (5) bromide dissociation from Sn(II)Br5 to Sn(II)Br4(2-). The intermediate Sn(III) species was confirmed by SECM(3-), where the Sn(III) generated at the Au tip was collected on a Au substrate in the tip generation/substrate collection mode when the distance between the tip and substrate was a few hundred nanometers.

  10. Electrochemical and in-situ scanning tunneling microscopy studies of bis(fluorosulfonyl)imide and bis(trifluoromethanesulfonyl)imide based ionic liquids on graphite and gold electrodes and lithium salt influence

    NASA Astrophysics Data System (ADS)

    Hu, Xiaoyan; Chen, Chunlei; Yan, Jiawei; Mao, Bingwei

    2015-10-01

    We report electrochemical and in-situ scanning tunneling microscopy (STM) studies of surface processes on graphite and Au(111) electrodes in N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide (Py13FSI) and N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (Py13TFSI) ionic liquids in the absence and presence of LiTFSI salt. In both of neat ionic liquids, the intercalation of cations and exfoliation of HOPG layers occur during cathodic excursion. However, the surface decomposition of FSI anions can form an effective protection film on the surface, which suppresses the intercalation and exfoliation processes, while the surface decomposition of TFSI anions mainly causes etching of the surface, which makes the intercalation and exfoliation easier to proceed. The addition of Li salt can promote the formation of the protective film, especially in Py13FSI, and thus significantly suppress the intercalation and exfoliation processes. The discrepancies between these two ionic liquids are caused by the different anion interactions with graphite. Additionally, comparisons of the behaviors on HOPG and on Au(111) confirm that the surface processes are crucially dependent on the nature of the electrode. Trace amounts of oxygen and water can cause the formation of a film-like structure on Au(111), but show no apparent influence on HOPG.

  11. Solid Electrolyte Interphase (SEI) at TiO2 Electrodes in Li-Ion Batteries: Defining Apparent and Effective SEI Based on Evidence from X-ray Photoemission Spectroscopy and Scanning Electrochemical Microscopy.

    PubMed

    Ventosa, Edgar; Madej, Edyta; Zampardi, Giorgia; Mei, Bastian; Weide, Philipp; Antoni, Hendrik; La Mantia, Fabio; Muhler, Martin; Schuhmann, Wolfgang

    2017-01-25

    The high (de)lithiation potential of TiO2 (ca. 1.7 V vs Li/Li(+) in 1 M Li(+)) decreases the voltage and, thus, the energy density of a corresponding Li-ion battery. On the other hand, it offers several advantages such as the (de)lithiation potential far from lithium deposition or absence of a solid electrolyte interphase (SEI). The latter is currently under controversial debate as several studies reported the presence of a SEI when operating TiO2 electrodes at potentials above 1.0 V vs Li/Li(+). We investigate the formation of a SEI at anatase TiO2 electrodes by means of X-ray photoemission spectroscopy (XPS) and scanning electrochemical microscopy (SECM). The investigations were performed in different potential ranges, namely, during storage (without external polarization), between 3.0-2.0 V and 3.0-1.0 V vs Li/Li(+), respectively. No SEI is formed when a completely dried and residues-free TiO2 electrode is cycled between 3.0 and 2.0 V vs Li/Li(+). A SEI is detected by XPS in the case of samples stored for 6 weeks or cycled between 3.0 and 1.0 V vs Li/Li(+). With use of SECM, it is verified that this SEI does not possess the electrically insulating character as expected for a "classic" SEI. Therefore, we propose the term apparent SEI for TiO2 electrodes to differentiate it from the protecting and effective SEI formed at graphite electrodes.

  12. Electrochemical Engineering

    ERIC Educational Resources Information Center

    Alkire, Richard

    1976-01-01

    Discusses an electrochemical engineering course that combines transport phenomena and basic physical chemistry. Lecture notes and homework problems are used instead of a textbook; an outline of lecture topics is presented. (MLH)

  13. Electrochemical Design of Optical Nanoantennas

    NASA Astrophysics Data System (ADS)

    Vasilchenko, V. E.; Kharintsev, S. S.; Salakhov, M. Kh.

    2015-09-01

    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.

  14. Electrochemical Techniques

    SciTech Connect

    Chen, Gang; Lin, Yuehe

    2008-07-20

    Sensitive and selective detection techniques are of crucial importance for capillary electrophoresis (CE), microfluidic chips, and other microfluidic systems. Electrochemical detectors have attracted considerable interest for microfluidic systems with features that include high sensitivity, inherent miniaturization of both the detection and control instrumentation, low cost and power demands, and high compatibility with microfabrication technology. The commonly used electrochemical detectors can be classified into three general modes: conductimetry, potentiometry, and amperometry.

  15. Electron microscopy investigation and electrochemical performance of carbon-coated LiFe0.7Mn0.2Ni0.1PO4 for lithium ion battery

    NASA Astrophysics Data System (ADS)

    Rohman, Fadli; Suwandi, Endang; Majid, Nurhalis; Subhan, Achmad

    2016-02-01

    The carbon-coated LiFe0.7Mn0.2Ni0.1PO4 was synthesized using solid state reaction method and sintering process. The carbon was coated on the surface of the LiFe0.7Mn0.2Ni0.1PO4 particle using citric acid as the carbon source. the crystal phase and diffraction peak of the particle was shown from X-Ray Diffraction characterization. The particle morphology and size distribution of this material was investigated using Scanning Electron Microscopy (SEM). The thickness of the carbon coating and the crystal lattice spacing was investigated using Transmission Electron Microscopy (TEM). The particle size, carbon coating thickness, and crystal lattice spacing were found to be 10 - 50 µm, 4 nm, and Å, respectively. The effect of the carbon layer on the surface of the LiFe0.7Mn0.2Ni0.1PO4 particle as a cathode material in lithium-ion battery exhibited in the electrochemical performance test as shown in cyclic voltammetry and charge-discharge measurement test. According to the cyclic voltammetry test, it was shown that the redox peaks of the carbon-coated LiFe0.7Mn0.2Ni0.1PO4 from Fe2+ to Fe3+ were at 3.579 V and 2.96 V, but there was lower peak at 3.52 V. This phenomenon indicated the presence of doped Mn and Ni. The specific capacity of carbon coated LiFe0.7Mn0.2Ni0.1PO4 was 49 mAh/g, which was higher than uncoated LiFe0.7Mn0.2Ni0.1PO4, 30 mAh/g. On the other hand, after 40 cycles the specific capacity of carbon-coated LiFe0.7Mn0.2Ni0.1PO4 was decreasing to 10%, while the specific capacity of uncoated LiFe0.7Mn0.2Ni0.1PO4 remained almost similar before and after 40 cycles. In term of columbic efficiency, carbon-coated LiFe0.7Mn0.2Ni0.1PO4 was more stable, better than uncoated LiFe0.7Mn0.2Ni0.1PO4. Moreover, all samples were in close proximity to 100% efficiency. The C-rates test result showed that the discharge C-rates ability of the carbon coated LiFe0.7Mn0.2Ni0.1PO4 had been better than uncoated LiFe0.7Mn0.2Ni0.1PO4. At 1.5 C rate, the capacity loss of carbon-coated LiFe0

  16. Fluorescence Microscopy

    PubMed Central

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

    2016-01-01

    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. PMID:25275114

  17. Electrochemical cell

    DOEpatents

    Redey, Laszlo I.; Vissers, Donald R.; Prakash, Jai

    1994-01-01

    An electrochemical cell having a bimodal positive electrode, a negative electrode of an alkali metal, and a compatible electrolyte including an alkali metal salt molten at the cell operating temperature. The positive electrode has an electrochemically active layer of at least one transition metal chloride at least partially present as a charging product, and additives of bromide and/or iodide and sulfur in the positive electrode or the electrolyte. Electrode volumetric capacity is in excess of 400 Ah/cm.sup.3 ; the cell can be 90% recharged in three hours and can operate at temperatures below 160.degree. C. There is also disclosed a method of reducing the operating temperature and improving the overall volumetric capacity of an electrochemical cell and for producing a positive electrode having a BET area greater than 6.times.10.sup.4 cm.sup.2 /g of Ni.

  18. Electrochemical cell

    DOEpatents

    Redey, Laszlo I.; Vissers, Donald R.; Prakash, Jai

    1996-01-01

    An electrochemical cell having a bimodal positive electrode, a negative electrode of an alkali metal, and a compatible electrolyte including an alkali metal salt molten at the cell operating temperature. The positive electrode has an electrochemically active layer of at least one transition metal chloride at least partially present as a charging product, and additives of bromide and/or iodide and sulfur in the positive electrode or the electrolyte. Electrode volumetric capacity is in excess of 400 Ah/cm.sup.3 ; the cell can be 90% recharged in three hours and can operate at temperatures below 160.degree. C. There is also disclosed a method of reducing the operating temperature and improving the overall volumetric capacity of an electrochemical cell and for producing a positive electrode having a BET area greater than 6.times.10.sup.4 cm.sup.2 /g of Ni.

  19. Electrochemical cell

    DOEpatents

    Redey, L.I.; Vissers, D.R.; Prakash, J.

    1996-07-16

    An electrochemical cell is described having a bimodal positive electrode, a negative electrode of an alkali metal, and a compatible electrolyte including an alkali metal salt molten at the cell operating temperature. The positive electrode has an electrochemically active layer of at least one transition metal chloride at least partially present as a charging product, and additives of bromide and/or iodide and sulfur in the positive electrode or the electrolyte. Electrode volumetric capacity is in excess of 400 Ah/cm{sup 3}; the cell can be 90% recharged in three hours and can operate at temperatures below 160 C. There is also disclosed a method of reducing the operating temperature and improving the overall volumetric capacity of an electrochemical cell and for producing a positive electrode having a BET area greater than 6{times}10{sup 4}cm{sup 2}/g of Ni. 6 figs.

  20. Electrochemical cell

    DOEpatents

    Redey, L.I.; Vissers, D.R.; Prakash, J.

    1994-02-01

    An electrochemical cell is described having a bimodal positive electrode, a negative electrode of an alkali metal, and a compatible electrolyte including an alkali metal salt molten at the cell operating temperature. The positive electrode has an electrochemically active layer of at least one transition metal chloride at least partially present as a charging product, and additives of bromide and/or iodide and sulfur in the positive electrode or the electrolyte. Electrode volumetric capacity is in excess of 400 Ah/cm[sup 3]; the cell can be 90% recharged in three hours and can operate at temperatures below 160 C. There is also disclosed a method of reducing the operating temperature and improving the overall volumetric capacity of an electrochemical cell and for producing a positive electrode having a BET area greater than 6[times]10[sup 4] cm[sup 2]/g of Ni. 8 figures.

  1. Electrochemical device

    DOEpatents

    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.

  2. Electrochemical construction

    DOEpatents

    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.

  3. Electrochemical capacitor

    DOEpatents

    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.

  4. Electrochemical Engineering.

    ERIC Educational Resources Information Center

    Alkire, Richard C.

    1983-01-01

    Discusses engineering ramifications of electrochemistry, focusing on current/potential distribution, evaluation of trade-offs between influences of different phenomena, use of dimensionless numbers to assist in scale-over to new operating conditions, and economics. Also provides examples of electrochemical engineering education content related to…

  5. Analytical Microscopy

    SciTech Connect

    Not Available

    2006-06-01

    In the Analytical Microscopy group, within the National Center for Photovoltaic's Measurements and Characterization Division, we combine two complementary areas of analytical microscopy--electron microscopy and proximal-probe techniques--and use a variety of state-of-the-art imaging and analytical tools. We also design and build custom instrumentation and develop novel techniques that provide unique capabilities for studying materials and devices. In our work, we collaborate with you to solve materials- and device-related R&D problems. This sheet summarizes the uses and features of four major tools: transmission electron microscopy, scanning electron microscopy, the dual-beam focused-ion-beam workstation, and scanning probe microscopy.

  6. Electrochemical Epitaxy

    DTIC Science & Technology

    1994-06-25

    formation. Frequently, the first atmic layer of the depositing element forms at a potential prior to, under, that needed to deposit the bulk element. Thiis...ps referred to as undepotential deposition (UPD). UPD is an importaM well studied and reviewed area of electrochemical surface science [4-6]. In...general, UPD results in deposits one atom thick (an atomic layer), although the absolute coveage is fequmty some function of the deposition potential. In

  7. Electrochemical cell

    DOEpatents

    Redey, Laszlo I.; Vissers, Donald R.; Prakash, Jai

    1994-01-01

    An electrochemical cell having an alkali metal negative electrode such as sodium and a positive electrode including Ni or transition metals, separated by a .beta." alumina electrolyte and NaAlCl.sub.4 or other compatible material. Various concentrations of a bromine, iodine and/or sulfur containing additive and pore formers are disclosed, which enhance cell capacity and power. The pore formers may be the ammonium salts of carbonic acid or a weak organic acid or oxamide or methylcellulose.

  8. Electrochemical cell

    SciTech Connect

    Walsh, F.M.

    1986-12-23

    This patent describes an electrochemical cell having a metal anode wherein the metal is selected from zinc and cadmium; a bromine cathode; and an aqueous electrolyte containing a metal bromide, the metal bromide having the same metal as the metal of the anode. The improvement described here comprises: a bromine complexing agent in the aqueous metal bromide electrolyte, the complexing agent consisting solely of a quaternary ammonium salt of an N-organo substituted alpha amino acid, ester, or betaine.

  9. Electrochemical cell

    DOEpatents

    Redey, L.I.; Myles, K.M.; Vissers, D.R.; Prakash, J.

    1996-07-02

    An electrochemical cell is described with a positive electrode having an electrochemically active layer of at least one transition metal chloride. A negative electrode of an alkali metal and a compatible electrolyte including an alkali metal salt molten at cell operating temperature is included in the cell. The electrolyte is present at least partially as a corrugated {beta}{double_prime} alumina tube surrounding the negative electrode interior to the positive electrode. The ratio of the volume of liquid electrolyte to the volume of the positive electrode is in the range of from about 0.1 to about 3. A plurality of stacked electrochemical cells is disclosed each having a positive electrode, a negative electrode of an alkali metal molten at cell operating temperature, and a compatible electrolyte. The electrolyte is at least partially present as a corrugated {beta}{double_prime} alumina sheet separating the negative electrode and interior to the positive electrodes. The alkali metal is retained in a porous electrically conductive ceramic, and seals for sealing the junctures of the electrolyte and the adjacent electrodes at the peripheries thereof. 8 figs.

  10. Electrochemical cell

    DOEpatents

    Redey, Laszlo I.; Myles, Kevin M.; Vissers, Donald R.; Prakash, Jai

    1996-01-01

    An electrochemical cell with a positive electrode having an electrochemically active layer of at least one transition metal chloride. A negative electrode of an alkali metal and a compatible electrolyte including an alkali metal salt molten at cell operating temperature is included in the cell. The electrolyte is present at least partially as a corrugated .beta." alumina tube surrounding the negative electrode interior to the positive electrode. The ratio of the volume of liquid electrolyte to the volume of the positive electrode is in the range of from about 0.1 to about 3. A plurality of stacked electrochemical cells is disclosed each having a positive electrode, a negative electrode of an alkali metal molten at cell operating temperature, and a compatible electrolyte. The electrolyte is at least partially present as a corrugated .beta." alumina sheet separating the negative electrode and interior to the positive electrodes. The alkali metal is retained in a porous electrically conductive ceramic, and seals for sealing the junctures of the electrolyte and the adjacent electrodes at the peripheries thereof.

  11. Electrochemical cell

    DOEpatents

    Nagy, Zoltan; Yonco, Robert M.; You, Hoydoo; Melendres, Carlos A.

    1992-01-01

    An electrochemical cell has a layer-type or sandwich configuration with a Teflon center section that houses working, reference and counter electrodes and defines a relatively narrow electrolyte cavity. The center section is surrounded on both sides with thin Teflon membranes. The membranes are pressed in place by a pair of Teflon inner frames which are in turn supported by a pair of outer metal frames. The pair of inner and outer frames are provided with corresponding, appropriately shaped slits that are in plane generally transverse to the plane of the working electrode and permit X-ray beams to enter and exit the cell through the Teflon membranes that cover the slits so that the interface between the working electrode and the electrolyte within the cell may be analyzed by transmission geometry. In one embodiment, the center section consists of two parts, one on top of the other. Alternatively, the center section of the electrochemical cell may consist of two intersliding pieces or may be made of a single piece of Teflon sheet material. The electrolyte cavity is shaped so that the electrochemical cell can be rotated 90.degree. in either direction while maintaining the working and counter electrodes submerged in the electrolyte.

  12. Electrochemical cell

    DOEpatents

    Nagy, Z.; Yonco, R.M.; You, H.; Melendres, C.A.

    1992-08-25

    An electrochemical cell has a layer-type or sandwich configuration with a Teflon center section that houses working, reference and counter electrodes and defines a relatively narrow electrolyte cavity. The center section is surrounded on both sides with thin Teflon membranes. The membranes are pressed in place by a pair of Teflon inner frames which are in turn supported by a pair of outer metal frames. The pair of inner and outer frames are provided with corresponding, appropriately shaped slits that are in plane generally transverse to the plane of the working electrode and permit X-ray beams to enter and exit the cell through the Teflon membranes that cover the slits so that the interface between the working electrode and the electrolyte within the cell may be analyzed by transmission geometry. In one embodiment, the center section consists of two parts, one on top of the other. Alternatively, the center section of the electrochemical cell may consist of two intersliding pieces or may be made of a single piece of Teflon sheet material. The electrolyte cavity is shaped so that the electrochemical cell can be rotated 90[degree] in either direction while maintaining the working and counter electrodes submerged in the electrolyte. 5 figs.

  13. Electrochemical cell

    DOEpatents

    Kaun, Thomas D.

    1984-01-01

    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 0.5-1.0 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 1-10 volume % of the electrode, an additive from the materials of graphitized carbon, aluminum-iron alloy, and/or magnesium oxide.

  14. Electrochemical cell

    DOEpatents

    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.

  15. Electrochemical cell

    DOEpatents

    Redey, L.I.; Vissers, D.R.; Prakash, J.

    1994-08-23

    An electrochemical cell is described having an alkali metal negative electrode such as sodium and a positive electrode including Ni or transition metals, separated by a [beta] alumina electrolyte and NaAlCl[sub 4] or other compatible material. Various concentrations of a bromine, iodine and/or sulfur containing additive and pore formers are disclosed, which enhance cell capacity and power. The pore formers may be the ammonium salts of carbonic acid or a weak organic acid or oxamide or methylcellulose. 6 figs.

  16. Correlative Microscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microscopy and Imaging offers many opportunities to collaborate and cooperate with scientists in many different fields nationally and internationally. Images have proven to be very important components in basic research, product development and understanding structure/function relationships in addit...

  17. Correlative microscopy.

    PubMed

    Loussert Fonta, Céline; Humbel, Bruno M

    2015-09-01

    In recent years correlative microscopy, combining the power and advantages of different imaging system, e.g., light, electrons, X-ray, NMR, etc., has become an important tool for biomedical research. Among all the possible combinations of techniques, light and electron microscopy, have made an especially big step forward and are being implemented in more and more research labs. Electron microscopy profits from the high spatial resolution, the direct recognition of the cellular ultrastructure and identification of the organelles. It, however, has two severe limitations: the restricted field of view and the fact that no live imaging can be done. On the other hand light microscopy has the advantage of live imaging, following a fluorescently tagged molecule in real time and at lower magnifications the large field of view facilitates the identification and location of sparse individual cells in a large context, e.g., tissue. The combination of these two imaging techniques appears to be a valuable approach to dissect biological events at a submicrometer level. Light microscopy can be used to follow a labelled protein of interest, or a visible organelle such as mitochondria, in time, then the sample is fixed and the exactly same region is investigated by electron microscopy. The time resolution is dependent on the speed of penetration and fixation when chemical fixatives are used and on the reaction time of the operator for cryo-fixation. Light microscopy can also be used to identify cells of interest, e.g., a special cell type in tissue or cells that have been modified by either transfections or RNAi, in a large population of non-modified cells. A further application is to find fluorescence labels in cells on a large section to reduce searching time in the electron microscope. Multiple fluorescence labelling of a series of sections can be correlated with the ultrastructure of the individual sections to get 3D information of the distribution of the marked proteins: array

  18. Electrochemical supercapacitors

    DOEpatents

    Rudge, Andrew J.; Ferraris, John P.; Gottesfeld, Shimshon

    1996-01-01

    A new class of electrochemical capacitors provides in its charged state a positive electrode including an active material of a p-doped material and a negative electrode including an active material of an n-doped conducting polymer, where the p-doped and n-doped materials are separated by an electrolyte. In a preferred embodiment, the positive and negative electrode active materials are selected from conducting polymers consisting of polythiophene, polymers having an aryl group attached in the 3-position, polymers having aryl and alkyl groups independently attached in the 3- and 4-positions, and polymers synthesized from bridged dimers having polythiophene as the backbone. A preferred electrolyte is a tetraalykyl ammonium salt, such as tetramethylammonium trifluoromethane sulphonate (TMATFMS), that provides small ions that are mobile through the active material, is soluble in acetonitrile, and can be used in a variety of capacitor configurations.

  19. Expansion Microscopy

    PubMed Central

    Chen, Fei; Tillberg, Paul W.; Boyden, Edward S.

    2014-01-01

    In optical microscopy, fine structural details are resolved by using refraction to magnify images of a specimen. Here we report the discovery that, by synthesizing a swellable polymer network within a specimen, it can be physically expanded, resulting in physical magnification. By covalently anchoring specific labels located within the specimen directly to the polymer network, labels spaced closer than the optical diffraction limit can be isotropically separated and optically resolved, a process we call expansion microscopy (ExM). Thus, this process can be used to perform scalable super-resolution microscopy with diffraction-limited microscopes. We demonstrate ExM with effective ~70 nm lateral resolution in both cultured cells and brain tissue, performing three-color super-resolution imaging of ~107 μm3 of the mouse hippocampus with a conventional confocal microscope. PMID:25592419

  20. Electrochemical synthesis of multisegmented nanowires

    SciTech Connect

    Kok, Kuan-Ying; Ng, Inn-Khuan; Saidin, Nur Ubaidah

    2012-11-27

    Electrochemical deposition has emerged as a promising route for nanostructure fabrication in recent years due to the many inherent advantages it possesses. This study focuses on the synthesis of high-aspect-ratio multisegmented Au/Ni nanowires using template-directed sequential electrochemical deposition techniques. By selectively removing the Ni segments in the nanowires, high-yield of pure gold nanorods of predetermined lengths was obtained. Alternatively, the sacrificial Ni segments in the nanowires can be galvanically displaced with Bi and Te to form barbells structures with Bi{sub x}Te{sub y} nanotubes attached to neighbouring gold segments. Detailed studies on the nanostructures obtained were carried out using various microscopy, diffraction and probebased techniques for structural, morphological and chemical characterizations.

  1. Electrochemical synthesis and surface characterization of (pyrrole+2-methylfuran) copolymer

    NASA Astrophysics Data System (ADS)

    Djaouane, Linda; Nessark, Belkacem; Sibous, Lakhdar

    2017-02-01

    Electrochemical copolymerization of pyrrole (Py) and 2-methylfuran (2 MF) was performed on platinum and ITO substrates in acetonitrile/lithium perchlorate solution, using cyclic voltammetry method. The electrochemical behavior of the modified electrode surface by polypyrrole, poly(2-methylfuran) homopolymers and (pyrrole+2-methylfuran) copolymer was characterized by cyclic voltammetry, electrochemical impedance spectroscopy (EIS), UV-visible spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). The cyclic voltammetry shows anodic and cathodic peaks which are characteristic of the oxidation and the reduction of the formed films. The electrochemical impedance spectroscopy confirmed the results obtained by cyclic voltammetry. AFM and SEM analyses proved as well that the morphology and the electrochemical properties of the polypyrrole film are modified in the presence of 2-methylfuran.

  2. Positron microscopy

    SciTech Connect

    Hulett, L.D. Jr.; Xu, J.

    1995-02-01

    The negative work function property that some materials have for positrons make possible the development of positron reemission microscopy (PRM). Because of the low energies with which the positrons are emitted, some unique applications, such as the imaging of defects, can be made. The history of the concept of PRM, and its present state of development will be reviewed. The potential of positron microprobe techniques will be discussed also.

  3. Microfluidic electrochemical reactors

    DOEpatents

    Nuzzo, Ralph G [Champaign, IL; Mitrovski, Svetlana M [Urbana, IL

    2011-03-22

    A microfluidic electrochemical reactor includes an electrode and one or more microfluidic channels on the electrode, where the microfluidic channels are covered with a membrane containing a gas permeable polymer. The distance between the electrode and the membrane is less than 500 micrometers. The microfluidic electrochemical reactor can provide for increased reaction rates in electrochemical reactions using a gaseous reactant, as compared to conventional electrochemical cells. Microfluidic electrochemical reactors can be incorporated into devices for applications such as fuel cells, electrochemical analysis, microfluidic actuation, pH gradient formation.

  4. High Power Electrochemical Capacitors

    DTIC Science & Technology

    2012-03-23

    electrochemical properties of vanadium oxide aerogels prepared by a freeze-drying process. Journal of the Electrochemical Society, 2004. 151(5): p...Electrochemical Society, 2002. 149(1): p. A26-A30. 12. Rolison, D.R. and B. Dunn, Electrically conductive oxide aerogels : new materials in...surface area vanadium oxide aerogels . Electrochemical and Solid-State Letters, 2000. 3(10): p. 457-459. 14. Shembel, E., et al., Synthesis, investigation

  5. Electrochemical methane sensor

    DOEpatents

    Zaromb, S.; Otagawa, T.; Stetter, J.R.

    1984-08-27

    A method and instrument including an electrochemical cell for the detection and measurement of methane in a gas by the oxidation of methane electrochemically at a working electrode in a nonaqueous electrolyte at a voltage about 1.4 volts vs R.H.E. (the reversible hydrogen electrode potential in the same electrolyte), and the measurement of the electrical signal resulting from the electrochemical oxidation.

  6. Plasmonic Imaging of Electrochemical Reactions of Single Nanoparticles.

    PubMed

    Fang, Yimin; Wang, Hui; Yu, Hui; Liu, Xianwei; Wang, Wei; Chen, Hong-Yuan; Tao, N J

    2016-11-15

    systems and nanoscale materials with high throughput. The plasmonic approach has two imaging modes: electrochemical current imaging and interfacial impedance imaging. The former images local electrochemical current associated with electrochemical reactions (faradic current), and the latter maps local interfacial impedance, including nonfaradic contributions (e.g., double layer charging). The plasmonic imaging technique can perform voltammetry (cyclic or square wave) in an analogous manner to the traditional electrochemical methods. It can also be integrated with bright field, dark field, and fluorescence imaging capabilities in one optical setup to provide additional capabilities. To date the plasmonic imaging technique has found various applications, including mapping of heterogeneous surface reactions, analysis of trace substances, detection of catalytic reactions, and measurement of graphene quantum capacitance. The plasmonic and other emerging optical imaging techniques (e.g., dark field and fluorescence microscopy), together with the scanning probe-based electrochemical imaging and single nanoparticle analysis techniques, provide new capabilities for one to study single nanoparticle electrochemistry with unprecedented spatial and temporal resolutions. In this Account, we focus on imaging of electrochemical reactions at single nanoparticles.

  7. Electrochemical activation of carbon nanotube/polymer composites.

    PubMed

    Sánchez, Samuel; Fàbregas, Esteve; Pumera, Martin

    2009-01-07

    Electrochemical activation of carbon nanotube/polysulfone composite electrodes for enhanced heterogeneous electron transfer is studied. The physicochemical insight into the electrochemical activation of carbon nanotube/polymer composites was provided by transmission electron microscopy, Raman spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry. Dopamine, ascorbic acid, NADH, and ferricyanide are used as a model redox system for evaluating the performance of activated carbon nanotube/polymer composite electrodes. We demonstrate that polymer wrapping of carbon nanotubes is subject to defects and to partial removal during activation. Such tunable activation of electrodes would enable on-demand activation of electrodes for satisfying the needs of sensing or energy storage devices.

  8. Electrochemical polypyrrole formation from pyrrole 'adlayer'.

    PubMed

    Plausinaitis, Deivis; Sinkevicius, Linas; Mikoliunaite, Lina; Plausinaitiene, Valentina; Ramanaviciene, Almira; Ramanavicius, Arunas

    2017-01-04

    In this research study, we investigated the morphology of polypyrrole nanostructures, which were formed during the electrochemical deposition of conducting polymer. An electrochemical quartz crystal microbalance (EQCM) cell equipped with a flow-through system was employed to exchange solutions of different compositions within the EQCM cell. When bare PBS buffer in the EQCM cell was exchanged with PBS buffer with pyrrole we observed a distinct increase in the resonance frequency Δf. This change in the resonance frequency and electrical capacitance, which was calculated from electrochemical impedance spectroscopy (EIS) data, illustrate that pyrrole on the surface of the gold electrode formed an adsorbed layer (adlayer). The formation of a pyrrole adlayer before the potential pulse that induced polymerization was investigated by QCM-based measurements. The electrochemical polymerization of this adlayer was induced by a single potential pulse and a nanostructured layer, which consisted of adsorbed polypyrrole (Ppy) nanoparticles with a diameter of 50 nm, was formed. QCM and EIS data revealed that by the next cycle of the electrochemical formation of Ppy, which was investigated after flow-through-based exchange of solutions, the initially formed Ppy surface was covered by the adlayer of pyrrole. This adlayer was desorbed when pyrrole was removed from the solution. When electrochemical polymerization was performed using 50 potential pulses, a Ppy layer, which had more complex morphology, was formed on the EQCM crystal. Scanning electron microscopy showed that the conductivity of this layer was unequally distributed. We observed that the polypyrrole layer formed by electrochemical deposition, which was performed using potential pulses, was formed out of aggregated spherical Ppy particles with a diameter of 50 nm.

  9. Electrochemical oxidation of cholesterol

    PubMed Central

    2015-01-01

    Summary Indirect cholesterol electrochemical oxidation in the presence of various mediators leads to electrophilic addition to the double bond, oxidation at the allylic position, oxidation of the hydroxy group, or functionalization of the side chain. Recent studies have proven that direct electrochemical oxidation of cholesterol is also possible and affords different products depending on the reaction conditions. PMID:25977713

  10. Electrochemical cell stack assembly

    DOEpatents

    Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

    2010-06-22

    Multiple stacks of tubular electrochemical cells having a dense electrolyte disposed between an anode and a cathode preferably deposited as thin films arranged in parallel on stamped conductive interconnect sheets or ferrules. The stack allows one or more electrochemical cell to malfunction without disabling the entire stack. Stack efficiency is enhanced through simplified gas manifolding, gas recycling, reduced operating temperature and improved heat distribution.

  11. Electrochemical thermodynamic measurement system

    DOEpatents

    Reynier, Yvan; Yazami, Rachid; Fultz, Brent T.

    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.

  12. Planar electrochemical device assembly

    DOEpatents

    Jacobson; Craig P. , Visco; Steven J. , De Jonghe; Lutgard C.

    2010-11-09

    A pre-fabricated electrochemical device having a dense electrolyte disposed between an anode and a cathode preferably deposited as thin films is bonded to a porous electrically conductive support. A second porous electrically conductive support may be bonded to a counter electrode of the electrochemical device. Multiple electrochemical devices may be bonded in parallel to a single porous support, such as a perforated sheet to provide a planar array. Planar arrays may be arranged in a stacked interconnected array. A method of making a supported electrochemical device is disclosed wherein the method includes a step of bonding a pre-fabricated electrochemical device layer to an existing porous metal or porous metal alloy layer.

  13. Planar electrochemical device assembly

    DOEpatents

    Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

    2007-06-19

    A pre-fabricated electrochemical device having a dense electrolyte disposed between an anode and a cathode preferably deposited as thin films is bonded to a porous electrically conductive support. A second porous electrically conductive support may be bonded to a counter electrode of the electrochemical device. Multiple electrochemical devices may be bonded in parallel to a single porous support, such as a perforated sheet to provide a planar array. Planar arrays may be arranged in a stacked interconnected array. A method of making a supported electrochemical device is disclosed wherein the method includes a step of bonding a pre-fabricated electrochemical device layer to an existing porous metal or porous metal alloy layer.

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

    ERIC Educational Resources Information Center

    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…

  15. Composite Nanostructured Material Fabrication By Electrochemical Scanning Probe Microscopy

    DTIC Science & Technology

    1992-10-31

    achieve selective electrodeposition onto a nanostructured surface and in techniques and procedures needed to create a nanoheterostructure , a class of... nanoheterostructures . As an example of such a structure we would start with a nanostructure consisting of a metal film of material A which has nanometer-scale...selective electrodeposition onto a nanostructured surface and in techniques and procedures needed to create a nanoheterostructure . The first attempts to

  16. Electrode for electrochemical cell

    DOEpatents

    Kaun, T.D.; Nelson, P.A.; Miller, W.E.

    1980-05-09

    An electrode structure for a secondary electrochemical cell includes an outer enclosure defining a compartment containing electrochemical active material. The enclosure includes a rigid electrically conductive metal sheet with perforated openings over major side surfaces. The enclosure can be assembled as first and second trays each with a rigid sheet of perforated electrically conductive metal at major side surfaces and normally extending flanges at parametric margins. The trays can be pressed together with moldable active material between the two to form an expandable electrode. A plurality of positive and negative electrodes thus formed are arranged in an alternating array with porous frangible interelectrode separators within the housing of the secondary electrochemical cell.

  17. Electrode for electrochemical cell

    DOEpatents

    Kaun, Thomas D.; Nelson, Paul A.; Miller, William E.

    1981-01-01

    An electrode structure for a secondary electrochemical cell includes an outer enclosure defining a compartment containing electrochemical active material. The enclosure includes a rigid electrically conductive metal sheet with perforated openings over major side surfaces. The enclosure can be assembled as first and second trays each with a rigid sheet of perforated electrically conductive metal at major side surfaces and normally extending flanges at parametric margins. The trays can be pressed together with moldable active material between the two to form an expandable electrode. A plurality of positive and negative electrodes thus formed are arranged in an alternating array with porous frangible interelectrode separators within the housing of the secondary electrochemical cell.

  18. Synthesis and electrochemical performance of polyaniline @MnO2/graphene ternary composites for electrochemical supercapacitors

    NASA Astrophysics Data System (ADS)

    Pan, Chao; Gu, Haiteng; Dong, Li

    2016-01-01

    We introduce a facile method to construct new ternary hierarchical nanocomposites by combining MnO2 coated one dimensional (1D) conducting polyaniline (PANI) nanowires with 2D graphene sheets (GNs). The hierarchical nanocomposite structures of PANI@MnO2/GNs (PMGNs) are further proved by X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The electrochemical characteristics of the electrodes made of the hierarchical structured PMGNs materials are determined by the CV and galvanostatic measurements. These electrochemical tests indicate that electrodes made of the nanostructured PMGNs exhibit an improved reversible capacitance of 695 F g-1 after 1000 cycles at a high current density of 4 A g-1. The ternary composites possess higher electrochemical capacitance than each individual component as supercapacitor electrode materials. Such intriguing electrochemical performance is mainly attributed to the synergistic effects of MnO2, PANI and graphene. The hierarchical ternary nanocomposites show excellent electrochemical properties for energy storage applications, which evidence their potential application as supercapacitors.

  19. Electrochemical Sensors: Functionalized Silica

    SciTech Connect

    Fryxell, Glen E.; Lin, Yuehe; Yantasee, Wassana

    2009-03-24

    This chapter summarizes recent devellopment of electrochemical sensors based on functionlized mesoporous silica materials. The nanomatrials based sensors have been developed for sensitive and selective enrironmental detection of toxic heavy metal and uranium ions.

  20. Advanced Electrochemical Waste Forms

    SciTech Connect

    Riley, Brian J.; Crum, Jarrod V.; McCloy, John S.; Matyas, Josef

    2011-12-01

    This is a brief description of PNNL's efforts in FY2011 towards developing advanced electrochemical waste forms. This is a short section that will become part of a larger document being put together by INL.

  1. Electrochemical Analysis of Neurotransmitters

    NASA Astrophysics Data System (ADS)

    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.

  2. ELECTROCHEMICAL DEGRADATION OF POLYCHLOROBIPHENYLS

    EPA Science Inventory

    Granular graphite is an ideal conductive material for electrochemical reduction technology applications in the field. Granular graphite was used to enhance the transfer of chlorinated aliphatic compounds in saturated, low permeability soils by electroosmosis. It was also used to ...

  3. Electrochemical Analysis of Neurotransmitters

    PubMed Central

    Bucher, Elizabeth S.; Wightman, R. Mark

    2016-01-01

    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. PMID:25939038

  4. Electrochemical heat engine

    DOEpatents

    Elliott, Guy R. B.; Holley, Charles E.; Houseman, Barton L.; Sibbitt, Jr., Wilmer L.

    1978-01-01

    Electrochemical heat engines produce electrochemical work, and mechanical motion is limited to valve and switching actions as the heat-to-work cycles are performed. The electrochemical cells of said heat engines use molten or solid electrolytes at high temperatures. One or more reactions in the cycle will generate a gas at high temperature which can be condensed at a lower temperature with later return of the condensate to electrochemical cells. Sodium, potassium, and cesium are used as the working gases for high temperature cells (above 600 K) with halogen gases or volatile halides being used at lower temperature. Carbonates and halides are used as molten electrolytes and the solid electrolyte in these melts can also be used as a cell separator.

  5. Electrochemical Analysis of Neurotransmitters.

    PubMed

    Bucher, Elizabeth S; Wightman, R Mark

    2015-01-01

    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.

  6. Preparation and characterization of STM tips for electrochemical studies

    NASA Astrophysics Data System (ADS)

    Nagahara, L. A.; Thundat, T.; Lindsay, S. M.

    1989-10-01

    We report on a fabrication technique for scanning tunneling microscopy (STM) tips for in situ electrochemical investigations. Unwanted Faradaic currents were minimized by insulating the STM tips with Apiezon wax. Cyclic voltammetry showed Apiezon wax to be inert in various electrolytes.

  7. Electrochemical Atomic Layer Processing

    DTIC Science & Technology

    1994-06-25

    where an atomic layer of an element is deposited , or removed, in a surface limited reaction. The potentials used are referred to as underpotentials in...the electrochemical literature. The atomic layer deposition process is referred to as underpotential deposition (UPD). 14. SUBJECT TERMS 15, NUMBER OF...reaction. The potentials used are referred to as underpotentials in the electrochemical literature. The atomic layer deposition process is referred to as

  8. Electrochemical Energy Storage Materials

    DTIC Science & Technology

    2012-07-01

    separated to allow the electrolyte diffusion in an electrochemical cell . Figure 9c shows a zoomed cross-sectional view of the TiO2 coated Ni...Electrochemical half- cells were assembled using the TiO2 coated Ni nanowire arrays (working electrode) and Li foil (counter electrode) separated by two layers... Solar Cells Using Coaxial Electrospinning.” James R. Deneault, Xiaoyin Xiao, Tae-Sik Kang, Joanna S. Wang, Chien M. Wai, Gail J. Brown, Michael F

  9. Solid state electrochemical composite

    DOEpatents

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

    2009-06-30

    Provided is a composite electrochemical device fabricated from highly electronically conductive materials such as metals, metal alloys, or electronically conductive ceramics. The electronic conductivity of the electrode substrate is maximized. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in ionic (electrochemical) devices such as fuel cells and electrolytic gas separation systems including oxygen generation system.

  10. Electrochemical Characterization of Ultrathin Cross-Linked Metal Nanoparticle Films.

    PubMed

    Han, Chu; Percival, Stephen J; Zhang, Bo

    2016-09-06

    Here we report the preparation, characterization, and electrochemical study of conductive, ultrathin films of cross-linked metal nanoparticles (NPs). Nanoporous films ranging from 40 to 200 nm in thickness composed of gold and platinum NPs of ∼5 nm were fabricated via a powerful layer-by-layer spin coating process. This process allows preparation of uniform NP films as large as 2 × 2 cm(2) with precise control over thickness, structure, and electrochemical and electrocatalytic properties. Gold, platinum, and bimetallic NP films were fabricated and characterized using cyclic voltammetry, scanning electron microscopy, and conductance measurements. Their electrocatalytic activity toward the oxygen reduction reaction (ORR) was investigated. Our results show that the electrochemical activity of such NP films is initially hindered by the presence of dense thiolate cross-linking ligands. Both electrochemical cycling and oxygen plasma cleaning are effective means in restoring their electrochemical activity. Gold NP films have higher electric conductivity than platinum possibly due to more uniform film structure and closer particle-particle distance. The electrochemical and electrocatalytic performance of platinum NP films can be greatly enhanced by the incorporation of gold NPs. This work focuses on electrochemical characterization of cross-linked NP films and demonstrates several unique properties. These include quick and easy preparation, ultrathin and uniform film thickness, tunable structure and composition, and transferability to many other substrates.

  11. Genomagnetic Electrochemical Biosensors

    NASA Astrophysics Data System (ADS)

    Wang, Joseph; Erdem, Arzum

    The use of nucleic acid technologies has significantly improved preparation and diagnostic procedures in life sciences. Nucleic acid layers combined with electrochemical or optical transducers produce a new kind of affinity biosensors as DNA Biosensor for small molecular weight molecules. Electrochemical DNA biosensors are attractive devices for converting the hybridization event into an analytical signal for obtaining sequence-specific information in connection with clinical, environmental or forensic investigations. DNA hybridization biosensors, based on electrochemical transduction of hybridization, couple the high specificity of hybridization reactions with the excellent sensitivity and portability of electrochemical transducers. The main goal in all researches is to design DNA biosensors for preparing a basis for the future DNA microarray system. DNA chip has now become a powerful tool in biological research, however the real clinic assay is still under development. Recently, there has been a great interest to the magnetic beads and/or nanoparticles labelled with metals such as gold, cadmium, silver, etc. for designing of novel electrochemical DNA biosensor approaches resulting in efficient separation. The attractive features of this technology include simple approach, rapid results, multi-analyte detection, low-cost per measurument, stable, and non-hazardous reagents, and reduced waste handling. Some of these new approaches and applications of the electrochemical DNA biosensors based on magnetic beads and its combining with nanoparticles labelled with metals are described and discussed.

  12. Facile and controllable electrochemical reduction of graphene oxide and its applications

    SciTech Connect

    Shao, Yuyan; Wang, Jun; Engelhard, Mark H.; Wang, Chong M.; Lin, Yuehe

    2010-01-01

    Graphene oxide is electrochemically reduced which is called electrochemically reduced graphene oxide (ER-G). ER-G is characterized with scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The oxygen content is significantly decreased and the sp 2 carbon is restored after electrochemical reduction. ER-G exhibits much higher electrochemical capacitance and cycling durability than carbon nanotubes (CNTs) and chemically reduced graphene; the specific capacitance measured with cyclic voltammetry (20 mV/s) is ~165 F/g, ~86 F/g, and ~100 F/g for ER-G, CNTs, and chemically reduced graphene,1 respectively. The electrochemical reduction of oxygen and hydrogen peroxide was greatly enhanced on ER-G electrodes as compared with CNTs. ER-G has shown a good potential for applications in energy storage, biosensors, and electrocatalysis.

  13. Reclamation of niobium compounds from ionic liquid electrochemical polishing of superconducting radio frequency cavities

    SciTech Connect

    Wixtrom, Alex I.; Buhler, Jessica E.; Reece, Charles E.; Abdel-Fattah, Tarek M.

    2013-06-01

    Recent research has shown that choline chloride (vitamin B4)-based solutions can be used as a greener alternative to acid-based electrochemical polishing solutions. This study demonstrated a successful method for electrochemical deposition of niobium compounds onto the surface of copper substrates using a novel choline chloride-based ionic liquid. Niobium ions present in the ionic liquid solution were dissolved into the solution prior to deposition via electrochemical polishing of solid niobium. A black coating was clearly visible on the surface of the Cu following deposition. This coating was analyzed using scanning electron microscopy (SEM), electron dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and X-ray fluorescence spectroscopy (XRF). This ionic liquid-based electrochemical deposition method effectively recycles previously dissolved niobium from electrochemical polishing of superconducting radio frequency (SRF) cavities.

  14. Electrochemical Biosensors - Sensor Principles and Architectures

    PubMed Central

    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

  15. Materials for electrochemical capacitors.

    PubMed

    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.

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

    PubMed

    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.

  17. Electrochemical Membrane Incinerator

    SciTech Connect

    Johnson, Dennis C.; Houk, Linda L.; Feng, Jianren

    1998-12-08

    Electrochemical incineration of benzoquinone was evaluated as a model for the mineralization of carbon in toxic aromatic compounds. A Ti or Pt anode was coated with a film of the oxides of Ti, Ru, Sn and Sb. This quaternary metal oxide film was stable; elemental analysis of the electrolyzed solution indicated the concentration of these metal ions to be 3 {micro}g/L or less. The anode showed good reactivity for the electrochemical incineration of benzoquinone. The use of a dissolved salt matrix as the so-called ''supporting electrolyte'' was eliminated in favor of a solid-state electrolyte sandwiched between the anode and cathode.

  18. Engineering electrochemical capacitor applications

    NASA Astrophysics Data System (ADS)

    Miller, John R.

    2016-09-01

    Electrochemical capacitor (EC) applications have broadened tremendously since EC energy storage devices were introduced in 1978. Then typical applications operated below 10 V at power levels below 1 W. Today many EC applications operate at voltages approaching 1000 V at power levels above 100 kW. This paper briefly reviews EC energy storage technology, shows representative applications using EC storage, and describes engineering approaches to design EC storage systems. Comparisons are made among storage systems designed to meet the same application power requirement but using different commercial electrochemical capacitor products.

  19. Electrochemical fabrication of capacitors

    DOEpatents

    Mansour, Azzam N.; Melendres, Carlos A.

    1999-01-01

    A film of nickel oxide is anodically deposited on a graphite sheet held in osition on an electrochemical cell during application of a positive electrode voltage to the graphite sheet while exposed to an electrolytic nickel oxide solution within a volumetrically variable chamber of the cell. An angularly orientated x-ray beam is admitted into the cell for transmission through the deposited nickel oxide film in order to obtain structural information while the film is subject to electrochemical and in-situ x-ray spectroscopy from which optimum film thickness, may be determined by comparative analysis for capacitor fabrication purposes.

  20. Electrochemical micro sensor

    DOEpatents

    Setter, Joseph R.; Maclay, G. Jordan

    1989-09-12

    A micro-amperometric electrochemical sensor for detecting the presence of a pre-determined species in a fluid material is disclosed. The sensor includes a smooth substrate having a thin coating of solid electrolytic material deposited thereon. The working and counter electrodes are deposited on the surface of the solid electrolytic material and adhere thereto. Electrical leads connect the working and counter electrodes to a potential source and an apparatus for measuring the change in an electrical signal caused by the electrochemical oxidation or reduction of the species. Alternatively, the sensor may be fabricated in a sandwich structure and also may be cylindrical, spherical or other shapes.

  1. Electrochemical membrane incinerator

    DOEpatents

    Johnson, Dennis C.; Houk, Linda L.; Feng, Jianren

    2001-03-20

    Electrochemical incineration of p-benzoquinone was evaluated as a model for the mineralization of carbon in toxic aromatic compounds. A Ti or Pt anode was coated with a film of the oxides of Ti, Ru, Sn and Sb. This quaternary metal oxide film was stable; elemental analysis of the electrolyzed solution indicated the concentration of these metal ions to be 3 .mu.g/L or less. The anode showed good reactivity for the electrochemical incineration of benzoquinone. The use of a dissolved salt matrix as the so-called "supporting electrolyte" was eliminated in favor of a solid-state electrolyte sandwiched between the anode and cathode.

  2. Separators for electrochemical cells

    DOEpatents

    Carlson, Steven Allen; Anakor, Ifenna Kingsley

    2014-11-11

    Provided are separators for use in an electrochemical cell comprising (a) an inorganic oxide and (b) an organic polymer, wherein the inorganic oxide comprises organic substituents. Preferably, the inorganic oxide comprises an hydrated aluminum oxide of the formula Al.sub.2O.sub.3.xH.sub.2O, wherein x is less than 1.0, and wherein the hydrated aluminum oxide comprises organic substituents, preferably comprising a reaction product of a multifunctional monomer and/or organic carbonate with an aluminum oxide, such as pseudo-boehmite and an aluminum oxide. Also provided are electrochemical cells comprising such separators.

  3. Dictionary of Microscopy

    NASA Astrophysics Data System (ADS)

    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. Electrochemical nitridation of metal surfaces

    DOEpatents

    Wang, Heli; Turner, John A.

    2015-06-30

    Electrochemical nitridation of metals and the produced metals are disclosed. An exemplary method of electrochemical nitridation of metals comprises providing an electrochemical solution at low temperature. The method also comprises providing a three-electrode potentiostat system. The method also comprises stabilizing the three-electrode potentiostat system at open circuit potential. The method also comprises applying a cathodic potential to a metal.

  5. Chemical imaging of surfaces with the scanning electrochemical microscope

    NASA Astrophysics Data System (ADS)

    Bard, Allen J.; Fan, Fu-Ren F.; Pierce, David T.; Unwin, Patrick R.; Wipf, David O.; Zhou, Feimeng

    1991-10-01

    Scanning electrochemical microscopy is a scanning probe technique that is based on faradaic current changes as a small electrode is moved across the surface of a sample. The images obtained depend on the sample topography and surface reactivity. The response of the scanning electrochemical microscope is sensitive to the presence of conducting and electroactive species, which makes it useful for imaging hetrogeneous surfaces. The principles and instrumentation used to obtain images and surface reaction-kinetic information are discussed, and examples of applications to the study of electrodes, minerals, and biological samples are given.

  6. Modification of the surface morphology of the silicon substrate for boron-doped diamond electrodes in electrochemical wastewater treatment applications

    NASA Astrophysics Data System (ADS)

    Bak, Ji-Yoon; Lee, Choong-Hyun; Kim, Jung-Do; Lim, Dae-Soon

    2016-01-01

    For electrochemical wastewater treatment applications, textured boron-doped diamond (BDD) electrodes were fabricated by using a simple and cost-effective etching process. On the basis of the surface area measurement, the etching time was optimized in order to achieve higher electrochemical wastewater treatment performance. The surface structure, electrochemical properties, and electrochemical oxidation performance of the electrodes were characterized by using Raman spectroscopy and atomic force microscopy, in addition to electrochemical techniques. The textured BDD electrode demonstrated a dense and large surface area with no change in the film's properties. The effective surface area of the textured BDD electrode was approximately twice as large as that of the planar BDD electrode. The electrochemical results clearly demonstrate that the enhanced surface area of the BDD electrode achieves a higher current efficiency and much lower energy consumption in the electrochemical oxidation of methyl-orange.

  7. Electro-chemical grinding

    NASA Technical Reports Server (NTRS)

    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.

  8. Electrochemical biosensors and nanobiosensors

    PubMed Central

    Hammond, Jules L.; Formisano, Nello; Carrara, Sandro; Tkac, Jan

    2016-01-01

    Electrochemical techniques have great promise for low-cost miniaturised easy-to-use portable devices for a wide range of applications–in particular, medical diagnosis and environmental monitoring. Different techniques can be used for biosensing, with amperometric devices taking the central role due to their widespread application in glucose monitoring. In fact, glucose biosensing takes an approximately 70% share of the biosensor market due to the need for diabetic patients to monitor their sugar levels several times a day, making it an appealing commercial market. In this review, we present the basic principles of electrochemical biosensor devices. A description of the different generations of glucose sensors is used to describe in some detail the operation of amperometric sensors and how the introduction of mediators can enhance the performance of the sensors. Electrochemical impedance spectroscopy is a technique being increasingly used in devices due to its ability to detect variations in resistance and capacitance upon binding events. Novel advances in electrochemical sensors, due to the use of nanomaterials such as carbon nanotubes and graphene, are presented as well as future directions that the field is taking. PMID:27365037

  9. Electrochemically formed 3D hierarchical thin films of cobalt-manganese (Co-Mn) hexacyanoferrate hybrids for electrochemical applications

    NASA Astrophysics Data System (ADS)

    Alam Venugopal, Narendra Kumar; Joseph, James

    2016-02-01

    Here we report the feasibility of forming 3D nanostructured hexacyanoferates of Cobalt and Manganese (Co-MnHCF) on GC surface by a facile electrochemical method. This 3D architecture on glassy carbon electrode characterised systematically by voltammetry and other physical characterisation techniques like Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform Infrared spectroscopy (FTIR) etc,. Electrochemical Quartz crystal microbalance (EQCM) studies helped out to calculate the total mass change during Co-MnHCF formation. Electrochemical studies reveal that the formal redox potentials of both Co and MnHCF films remained close to that of newly formed Co-MnHCF hybrid films. These 3D modified films were successfully applied for two different electrochemical applications i) For pseudocapacitor studies in KNO3 medium ii) Investigated the electrocatalytic behaviour of redox film towards water oxidation reaction in alkaline medium. Electrochemical performances of newly formed Co-MnHCF are compared with their individual transition metal (Co, Mn) hexacyanoferrates. The resulting material shows a specific capacitance of 350 F g-1 through its fast reversible redox reaction of electrochemically formed Co-MnHCF modified film. Interestingly we showed the overpotential of 450 mV (from its thermodynamic voltage 1.2 V) to attain its optimum current density of 10 mA cm-2 for O2 evolution in alkaline medium.

  10. Electrochemical systems configured to harvest heat energy

    DOEpatents

    Lee, Seok Woo; Yang, Yuan; Ghasemi, Hadi; Chen, Gang; Cui, Yi

    2017-01-31

    Electrochemical systems for harvesting heat energy, and associated electrochemical cells and methods, are generally described. The electrochemical cells can be configured, in certain cases, such that at least a portion of the regeneration of the first electrochemically active material is driven by a change in temperature of the electrochemical cell. The electrochemical cells can be configured to include a first electrochemically active material and a second electrochemically active material, and, in some cases, the absolute value of the difference between the first thermogalvanic coefficient of the first electrochemically active material and the second thermogalvanic coefficient of the second electrochemically active material is at least about 0.5 millivolts/Kelvin.

  11. Electrochemical behavior of chemically synthesized selenium thin film.

    PubMed

    Patil, A M; Kumbhar, V S; Chodankar, N R; Lokhande, A C; Lokhande, C D

    2016-05-01

    The facile and low cost simple chemical bath deposition (CBD) method is employed to synthesize red colored selenium thin films. These selenium films are characterized for structural, morphological, topographical and wettability studies. The X-ray diffraction (XRD) pattern showed the crystalline nature of selenium thin film with hexagonal crystal structure. The scanning electron microscopy (SEM) study displays selenium nanoparticles ranging from 20 to 475 nm. A specific surface area of 30.5 m(2) g(-1) is observed for selenium nanoparticles. The selenium nanoparticles hold mesopores in the range of 1.39 nm, taking benefits of the good physicochemical stability and excellent porosity. Subsequently, the electrochemical properties of selenium thin films are deliberated by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) techniques. The selenium thin film shows specific capacitance (Cs) of 21.98 F g(-1) with 91% electrochemical stability.

  12. Axial Plane Optical Microscopy

    PubMed Central

    Li, Tongcang; Ota, Sadao; Kim, Jeongmin; Wong, Zi Jing; Wang, Yuan; Yin, Xiaobo; Zhang, Xiang

    2014-01-01

    We present axial plane optical microscopy (APOM) that can, in contrast to conventional microscopy, directly image a sample's cross-section parallel to the optical axis of an objective lens without scanning. APOM combined with conventional microscopy simultaneously provides two orthogonal images of a 3D sample. More importantly, APOM uses only a single lens near the sample to achieve selective-plane illumination microscopy, as we demonstrated by three-dimensional (3D) imaging of fluorescent pollens and brain slices. This technique allows fast, high-contrast, and convenient 3D imaging of structures that are hundreds of microns beneath the surfaces of large biological tissues. PMID:25434770

  13. Light sheet microscopy.

    PubMed

    Weber, Michael; Mickoleit, Michaela; Huisken, Jan

    2014-01-01

    This chapter introduces the concept of light sheet microscopy along with practical advice on how to design and build such an instrument. Selective plane illumination microscopy is presented as an alternative to confocal microscopy due to several superior features such as high-speed full-frame acquisition, minimal phototoxicity, and multiview sample rotation. Based on our experience over the last 10 years, we summarize the key concepts in light sheet microscopy, typical implementations, and successful applications. In particular, sample mounting for long time-lapse imaging and the resulting challenges in data processing are discussed in detail.

  14. Liquid Cell Transmission Electron Microscopy.

    PubMed

    Liao, Hong-Gang; Zheng, Haimei

    2016-05-27

    Liquid cell transmission electron microscopy (TEM) has attracted significant interest in recent years. With nanofabricated liquid cells, it has been possible to image through liquids using TEM with subnanometer resolution, and many previously unseen materials dynamics have been revealed. Liquid cell TEM has been applied to many areas of research, ranging from chemistry to physics, materials science, and biology. So far, topics of study include nanoparticle growth and assembly, electrochemical deposition and lithiation for batteries, tracking and manipulation of nanoparticles, catalysis, and imaging of biological materials. In this article, we first review the development of liquid cell TEM and then highlight progress in various areas of research. In the study of nanoparticle growth, the electron beam can serve both as the illumination source for imaging and as the input energy for reactions. However, many other research topics require the control of electron beam effects to minimize electron beam damage. We discuss efforts to understand electron beam-liquid matter interactions. Finally, we provide a perspective on future challenges and opportunities in liquid cell TEM.

  15. Liquid Cell Transmission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Liao, Hong-Gang; Zheng, Haimei

    2016-05-01

    Liquid cell transmission electron microscopy (TEM) has attracted significant interest in recent years. With nanofabricated liquid cells, it has been possible to image through liquids using TEM with subnanometer resolution, and many previously unseen materials dynamics have been revealed. Liquid cell TEM has been applied to many areas of research, ranging from chemistry to physics, materials science, and biology. So far, topics of study include nanoparticle growth and assembly, electrochemical deposition and lithiation for batteries, tracking and manipulation of nanoparticles, catalysis, and imaging of biological materials. In this article, we first review the development of liquid cell TEM and then highlight progress in various areas of research. In the study of nanoparticle growth, the electron beam can serve both as the illumination source for imaging and as the input energy for reactions. However, many other research topics require the control of electron beam effects to minimize electron beam damage. We discuss efforts to understand electron beam-liquid matter interactions. Finally, we provide a perspective on future challenges and opportunities in liquid cell TEM.

  16. System level electrochemical principles

    NASA Technical Reports Server (NTRS)

    Thaller, L. H.

    1985-01-01

    The traditional electrochemical storage concepts are difficult to translate into high power, high voltage multikilowatt storage systems. The increased use of electronics, and the use of electrochemical couples that minimize the difficulties associated with the corrective measures to reduce the cell to cell capacity dispersion were adopted by battery technology. Actively cooled bipolar concepts are described which represent some attractive alternative system concepts. They are projected to have higher energy densities lower volumes than current concepts. They should be easier to scale from one capacity to another and have a closer cell to cell capacity balance. These newer storage system concepts are easier to manage since they are designed to be a fully integrated battery. These ideas are referred to as system level electrochemistry. The hydrogen-oxygen regenerative fuel cells (RFC) is probably the best example of the integrated use of these principles.

  17. Electrochemical Deposition of Niobium onto the Surface of Copper Using a Novel Choline Chloride-Based Ionic Liquid

    SciTech Connect

    Wixtroma, Alex I.; Buhlera, Jessica E.; Reece, Charles E.; Abdel-Fattah, Tarek M.

    2013-06-01

    Recent research has shown that choline chloride-based solutions can be used to replace acid-based electrochemical polishing solutions. In this study niobium metal was successfully deposited on the surface of copper substrate via electrochemical deposition using a novel choline chloride-based ionic liquid. The niobium metal used for deposition on the Cu had been dissolved in the solution from electrochemical polishing of a solid niobium piece prior to the deposition. The visible coating on the surface of the Cu was analyzed using scanning electron microscopy (SEM) and electron dispersive x-ray spectroscopy (EDX). This deposition method effectively recycles previously dissolved niobium from electrochemical polishing.

  18. Electrochemical storage cell

    SciTech Connect

    Haberfellner, F.; Prappacher, G.

    1985-01-08

    Electrochemical storage cell of the sodium and sulfur type with at least one anode space for receiving the anolyte and a cathode space for receiving the catholyte, which are separated from each other by an alkali ion-conducting solid electrolyte and are bounded at least in some areas by a metallic housing. The cathode space is in communication via at least one connecting element with at least one supply container for the sodium polysulfide being formed in the chemical reaction.

  19. Electrochemical storage cell

    SciTech Connect

    Steinleitner, G.

    1984-05-01

    Electrochemical storage cell or battery with at least one anode space for receiving the anolyte and one cathode space for receiving the catholyte which spaces are separated from each other by an alkali ion-conducting solid electrolyte and are bounded at least in some places by a metallic housing. A safety space which is subdivided into at least two safety zones, adjoins at least in some places, the solid electrolyte.

  20. Molten Salt Electrochemical Systems.

    DTIC Science & Technology

    1983-05-31

    metal tetrafluoroborates were examined for similar behavior. Commercial samples of the lithium, sodium and potassium salts were used, while the...REPORT a PERID C £0 inal, 1 June 1980-31 March Molten Salt Electrochemical Systems 1983 6 PERFORMING OŘG. REPORT NUMBER 7. AUTHOR(a) I CONTRACT OR...dilfferent from Reporl) IS. KEY WORDS (Continue ora ow... side 55 n~cssay and Identify by block number ) Molten Salt , Phase Diagram, Electrolyte 30

  1. Remote electrochemical sensor

    DOEpatents

    Wang, Joseph; Olsen, Khris; Larson, David

    1997-01-01

    An electrochemical sensor for remote detection, particularly useful for metal contaminants and organic or other compounds. The sensor circumvents technical difficulties that previously prevented in-situ remote operations. The microelectrode, connected to a long communications cable, allows convenient measurements of the element or compound at timed and frequent intervals and instrument/sample distances of ten feet to more than 100 feet. The sensor is useful for both downhole groundwater monitoring and in-situ water (e.g., shipboard seawater) analysis.

  2. Electrochemical corrosion studies

    NASA Technical Reports Server (NTRS)

    Knockemus, W. W.

    1986-01-01

    The objective was to gain familiarity with the Model 350 Corrosion Measurement Console, to determine if metal protection by grease coatings can be measured by the polarization-resistance method, and to compare corrosion rates of 4130 steel coated with various greases. Results show that grease protection of steel may be determined electrochemically. Studies were also conducted to determine the effectiveness of certain corrosion inhibitors on aluminum and steel.

  3. Electrochemical flow capacitors

    DOEpatents

    Gogotsi, Yury; Presser, Volker; Kumbur, Emin Caglan

    2015-10-27

    The present invention generally relates to devices for energy storage technologies, and more particularly to electrochemical flow capacitor systems and applications. In some aspects, these flow capacitors have at least one electrode comprising a non-stationary solid or semi-solid composition comprising supercapacitive particles and an electrolytic solvent in electrical communication with at least one current collector, and energy is stored and/or released by charging and/or discharging the electrode(s).

  4. Atomic force microscopy of biological samples.

    PubMed

    Allison, David P; Mortensen, Ninell P; Sullivan, Claretta J; Doktycz, Mitchel J

    2010-01-01

    The ability to evaluate structural-functional relationships in real time has allowed scanning probe microscopy (SPM) to assume a prominent role in post genomic biological research. In this mini-review, we highlight the development of imaging and ancillary techniques that have allowed SPM to permeate many key areas of contemporary research. We begin by examining the invention of the scanning tunneling microscope (STM) by Binnig and Rohrer in 1982 and discuss how it served to team biologists with physicists to integrate high-resolution microscopy into biological science. We point to the problems of imaging nonconductive biological samples with the STM and relate how this led to the evolution of the atomic force microscope (AFM) developed by Binnig, Quate, and Gerber, in 1986. Commercialization in the late 1980s established SPM as a powerful research tool in the biological research community. Contact mode AFM imaging was soon complemented by the development of non-contact imaging modes. These non-contact modes eventually became the primary focus for further new applications including the development of fast scanning methods. The extreme sensitivity of the AFM cantilever was recognized and has been developed into applications for measuring forces required for indenting biological surfaces and breaking bonds between biomolecules. Further functional augmentation to the cantilever tip allowed development of new and emerging techniques including scanning ion-conductance microscopy (SICM), scanning electrochemical microscope (SECM), Kelvin force microscopy (KFM) and scanning near field ultrasonic holography (SNFUH).

  5. Atomic force microscopy of biological samples

    SciTech Connect

    Doktycz, Mitchel John

    2010-01-01

    The ability to evaluate structural-functional relationships in real time has allowed scanning probe microscopy (SPM) to assume a prominent role in post genomic biological research. In this mini-review, we highlight the development of imaging and ancillary techniques that have allowed SPM to permeate many key areas of contemporary research. We begin by examining the invention of the scanning tunneling microscope (STM) by Binnig and Rohrer in 1982 and discuss how it served to team biologists with physicists to integrate high-resolution microscopy into biological science. We point to the problems of imaging nonconductive biological samples with the STM and relate how this led to the evolution of the atomic force microscope (AFM) developed by Binnig, Quate, and Gerber, in 1986. Commercialization in the late 1980s established SPM as a powerful research tool in the biological research community. Contact mode AFM imaging was soon complemented by the development of non-contact imaging modes. These non-contact modes eventually became the primary focus for further new applications including the development of fast scanning methods. The extreme sensitivity of the AFM cantilever was recognized and has been developed into applications for measuring forces required for indenting biological surfaces and breaking bonds between biomolecules. Further functional augmentation to the cantilever tip allowed development of new and emerging techniques including scanning ion-conductance microscopy (SICM), scanning electrochemical microscope (SECM), Kelvin force microscopy (KFM) and scanning near field ultrasonic holography (SNFUH).

  6. Electrochemical Quartz Crystal Nanobalance

    NASA Astrophysics Data System (ADS)

    Inzelt, György

    The method of piezoelectric microgravimetry (nanogravimetry) using an electrochemical quartz crystal microbalance (EQCM) or nanobalance (EQCN) can be considered as a novel and much more sensitive version of electrogravimetry. The EQCN technique has become a widely used technique in several areas of electrochemistry, electroanalytical chemistry, bioelectrochemistry, etc. [1-10]. Obviously, mass changes occurring during adsorption, sorption, electrosorption, electrodeposition, or spontaneous deposition can be followed, which is very helpful for the elucidation of reaction mechanism via identification of the species accumulated on the surface. These investigations include metal and alloy deposition, underpotential deposition, electroplating, synthesis of conducting polymers by electropolymerization, adsorption of biologically active materials, and analytical determination of small ions and biomolecules. Of course, the opposite processes, i.e., spontaneous dissolution, electrodissolution, corrosion, can also be studied. Electrochemical oscillations, in which the formation and oxidation of chemisorbed molecular fragments play a determining role, have been studied, too. The majority of the investigations have been devoted to ion and solvent transport associated with the redox transformations of electrochemically active polymers. Similar studies have been carried out regarding polynuclear surface layers such as metal hexacyanometalates as well as inorganic and organic microcrystals of different compositions.

  7. ELECTROCHEMICAL POWER FOR TRANSPORTATION

    SciTech Connect

    Cairns, Elton J.; Hietbrink, Earl H.

    1981-01-01

    This section includes some historical background of the rise and fall and subsequent rebirth of the electric vehicle; and a brief discussion of current transportation needs, and environmental and energy utilization issues that resulted in the renewed interest in applying electrochemical energy conversion technology to electric vehicle applications. Although energy utilization has evolved to be the most significant and important issue, the environmental issue will be discussed first in this section only because of its chronological occurrence. The next part of the chapter is a review of passenger and commercial electric vehicle technology with emphasis on vehicle design and demonstrated performance of vehicles with candidate power sources being developed. This is followed by a discussion of electrochemical power source requirements associated with future electric vehicles that can play a role in meeting modern transportation needs. The last part of the chapter includes first a discussion of how to identify candidate electrochemical systems that might be of interest in meeting electric vehicle power source requirements. This is then followed by a review of the current technological status of these systems and a discussion of the most significant problems that must be resolved before each candidate system can be a viable power source.

  8. A compact analytical formalism for current transients in electrochemical systems.

    PubMed

    Nair, Pradeep R; Alam, Muhammad A

    2013-01-21

    Micro- and nanostructured electrodes form an integral part of a wide variety of electrochemical systems for biomolecular detection, batteries, solar cells, scanning electrochemical microscopy, etc. Given the complexity of the electrode structures, the Butler-Volmer formalism of redox reactions, and the diffusion transport of redox species, it is hardly surprising that only a few problems are amenable to closed-form, compact analytical solutions. While numerical solutions are widely used, it is often difficult to integrate the insights gained into the design and optimization of electrochemical systems. In this article, we develop a comprehensive analytical formalism for current transients that not only anticipate the responses of complex electrode structures to complicated voltammetry measurements, but also intuitively interpret diverse experiments such as redox detection of molecules at nanogap electrodes, scanning electrochemical microscopy, etc. The results from the analytical model, well supported through detailed numerical simulations and experimental data from the literature, have broad implications in the design and optimization of nanostructured electrodes for healthcare and energy storage applications.

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

    PubMed

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

    2017-03-27

    Pulse electrochemical nanopatterning (PECN), a non-contact scanning probe lithography (NC-SPL) process using ultrashort voltage pulses, is based primarily on an electrochemical machining (ECM) 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.

  10. Lasers for nonlinear microscopy.

    PubMed

    Wise, Frank

    2013-03-01

    Various versions of nonlinear microscopy are revolutionizing the life sciences, almost all of which are made possible because of the development of ultrafast lasers. In this article, the main properties and technical features of short-pulse lasers used in nonlinear microscopy are summarized. Recent research results on fiber lasers that will impact future instruments are also discussed.

  11. Adsorption and Assembly of Ions and Organic Molecules at Electrochemical Interfaces: Nanoscale Aspects

    NASA Astrophysics Data System (ADS)

    Yoshimoto, Soichiro; Itaya, Kingo

    2013-06-01

    We describe the history of electrochemical scanning tunneling microscopy (STM) and advances made in this field during the past 20 years. In situ STM allows one to monitor various electrode processes, such as the underpotential deposition of copper and silver ions; the specific adsorption of iodine and sulfate/bisulfate ions; electrochemical dissolution processes of silicon and gold single-crystal surfaces in electrolyte solutions; and the molecular assembly of metalloporphyrins, metallophthalocyanines, and fullerenes, at atomic and/or molecular resolution. Furthermore, a laser confocal microscope, combined with a differential interference contrast microscope, enables investigation of the dynamics of electrochemical processes at atomic resolution.

  12. Adsorption and assembly of ions and organic molecules at electrochemical interfaces: nanoscale aspects.

    PubMed

    Yoshimoto, Soichiro; Itaya, Kingo

    2013-01-01

    We describe the history of electrochemical scanning tunneling microscopy (STM) and advances made in this field during the past 20 years. In situ STM allows one to monitor various electrode processes, such as the underpotential deposition of copper and silver ions; the specific adsorption of iodine and sulfate/bisulfate ions; electrochemical dissolution processes of silicon and gold single-crystal surfaces in electrolyte solutions; and the molecular assembly of metalloporphyrins, metallophthalocyanines, and fullerenes, at atomic and/or molecular resolution. Furthermore, a laser confocal microscope, combined with a differential interference contrast microscope, enables investigation of the dynamics of electrochemical processes at atomic resolution.

  13. Coimmobilization of urease and glutamate dehydrogenase in electrochemically prepared polypyrrole-polyvinyl sulfonate films.

    PubMed

    Gambhir, A; Gerard, M; Mulchandani, A K; Malhotra, B D

    2001-01-01

    Immobilization of urease and glutamate dehydrogenase enzymes in electrochemically prepared polypyrrole-polyvinyl sulfonate films (PPY-PVS) was carried out using physical adsorption and electrochemical entrapment techniques. Detailed studies on optimum pH, Fourier transform infrared spectroscopy, cyclic voltammetry, and scanning electron microscopy of the enzymes in the immobilized state were conducted. The value of the apparent Michaelis-Menten constant was experimentally determined to be 2.5 and 2.7 for physically adsorbed and electrochemically entrapped urease in PPY-PVS films, respectively.

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Space Electrochemical Research and Technology

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The proceedings of NASA's third Space Electrochemical Research and Technology (SERT) conference are presented. The objective of the conference was to assess the present status and general thrust of research and development in those areas of electrochemical technology required to enable NASA missions in the next century. The conference provided a forum for the exchange of ideas and opinions of those actively involved in the field, in order to define new opportunities for the application of electrochemical processes in future NASA missions. Papers were presented in three technical areas: the electrochemical interface, the next generation in aerospace batteries and fuel cells, and electrochemistry for nonenergy storage applications.

  16. Electrochemical Sensors for Clinic Analysis

    PubMed Central

    Wang, You; Xu, Hui; Zhang, Jianming; Li, Guang

    2008-01-01

    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. PMID:27879810

  17. Continuous organic electrochemical synthesis

    SciTech Connect

    Nobe, K.; Baizer, M.; Pintauro, P.; Park, K.; Gilbert, S.

    1984-07-01

    The electrochemical oxidation of glucose to gluconic acid and reduction of glucose to sorbitol has been successfully paired in an undivided packed bed electrode flow cell. The use of a Raney nickel powder catalytic cathode significantly improved the current efficiency for sorbitol production, as compared to a high hydrogen overpotential Zn(Hg) cathode. The optimum operating conditions for the paired synthesis are: activity W-2 Raney nickel powder cathode, graphite chip anode, a 1.6 M glucose and 0.4 M CaBr/sub 2/ initial solution composition, pH 6-7, 60/sup 0/C solution temperature, a current density of 250 to 500 mA and a solution volumetric flow rate of 100 ml min/sup -1/. Under these conditions the sorbitol current efficiencies are at least 80%, the glucose acid current efficiencies are 100% and the product yields are quantitative. A separation scheme for the paired synthesis has also been devised. It consists of the precipitation of the oxidation product (calcium gluconate) and the ethanol extraction of glucose and CaBr/sub 2/ from sorbitol. Based on a preliminary economic analysis of the cost of raw materials, energy and the electrochemical cell and separation equipment the cost of producing 1 lb calcium gluconate and 0.68 lb sorbitol in a paired synthesis was estimated to be $0.896. The cost of producing the same amount of sorbitol and calcium gluconate in separate electrochemical cells was calculated to be $1.20. Thus, the paired synthesis appears to be an economically viable process.

  18. Electrochemical incineration of wastes

    NASA Technical Reports Server (NTRS)

    Bockris, J. O. M.; Bhardwaj, R. C.; Tennakoon, C. L. K.

    1993-01-01

    There is an increasing concern regarding the disposal of human wastes in space vehicles. It is of utmost importance to convert such wastes into harmless products which can be recycled into an Environmental Life Support System (CELSS), which incorporates the growth of plants (e.g. wheat) and algae to supplement the diet of the astronauts. Chemical treatments have proven relatively unsatisfactory and tend to be increasingly so with increase of the mission duration. Similarly, the use of heat to destroy wastes and convert them to CO2 by the use of air or oxygen has the disadvantage and difficulty of dissipating heat in a space environment and to the inevitable presence of oxides of nitrogen and carbon monoxide in the effluent gases. In particular, electrochemical techniques offer several advantages including low temperatures which may be used and the absence of any NO and CO in the evolved gases. Successful research has been carried out in the electrochemical oxidation of wastes over the last several years. The major task for 1992 was to conduct parametric studies in preparation for the building of a breadboard system, i.e., an actual practical device to consume the daily waste output of one astronaut in 24 hours, electrochemical incineration of human wastes in space vehicles. One of the main objectives was to decide on the type of three dimensional or other electrode system that would suit this purpose. The various types of electrode systems which were considered for this purpose included: rotating disc electrode, micro-electrode (an array), vibrating electrode, jet electrode, and packed bed electrode.

  19. Divided electrochemical cell assembly

    SciTech Connect

    King, Ch. J. H.

    1985-02-19

    A divided electrochemical cell assembly comprises stacked bipolar substantially square parallel planar electrodes and membranes. The corners and edges of the electrodes with bordering insulative spacers in juxtaposition with the chamber walls define four electrolyte circulation manifolds. Anolyte and catholyte channeling means permit the separate introduction of anolyte and catholyte into two of the manifolds and the withdrawal of anolyte and catholyte separately from at least two other manifolds. The electrodes and membranes are separated from one another by the insulative spacers which are also channeling means disposed to provide electrolyte channels across the interfaces of adjacent electrodes and membranes.

  20. Electrochemical storage cell

    SciTech Connect

    Fischer, W.; Hasenauer, D.

    1983-09-20

    An electrochemical storage cell is disclosed based on alkali metal and chalcogen comprising at least one anode space for the alkali metal anolyte and a cathode space for the chalcogen catholyte, with the anode space and the cathode space separated from each other by an alkali ion-conducting solid electrolyte wall and a metallic housing bounding the cell. The solid electrolyte wall has a plurality of spaced, outwardly extending hollow recesses, and at least one current collector disposed between each pair of adjacent recesses.

  1. Electrochemical storage cell

    SciTech Connect

    Steinleitner, G.

    1985-05-07

    Electrochemical storage cell of the alkali metal and chalcogen type with at least one anode space for the alkali metal anolyte, and a cathode space for the chalcogen catholyte, with the anode space and the cathode space separated from each other by an alkali ion-conducting solid electrolyte wall, the improvement comprising the addition in the anode space of sodium and of a capturing material with O/sub 2/-getter properties in an amount sufficient to absorb detrimental bound or free oxygen.

  2. Amplifying Electrochemical Indicators

    NASA Technical Reports Server (NTRS)

    Fan, Wenhong; Li, Jun; Han, Jie

    2004-01-01

    Dendrimeric reporter compounds have been invented for use in sensing and amplifying electrochemical signals from molecular recognition events that involve many chemical and biological entities. These reporter compounds can be formulated to target specific molecules or molecular recognition events. They can also be formulated to be, variously, hydrophilic or amphiphilic so that they are suitable for use at interfaces between (1) aqueous solutions and (2) electrodes connected to external signal-processing electronic circuits. The invention of these reporter compounds is expected to enable the development of highly miniaturized, low-power-consumption, relatively inexpensive, mass-producible sensor units for diverse applications.

  3. Electrochemical thinning of silicon

    DOEpatents

    Medernach, J.W.

    1994-01-11

    Porous semiconducting material, e.g. silicon, is formed by electrochemical treatment of a specimen in hydrofluoric acid, using the specimen as anode. Before the treatment, the specimen can be masked. The porous material is then etched with a caustic solution or is oxidized, depending of the kind of structure desired, e.g. a thinned specimen, a specimen, a patterned thinned specimen, a specimen with insulated electrical conduits, and so on. Thinned silicon specimen can be subjected to tests, such as measurement of interstitial oxygen by Fourier transform infra-red spectroscopy (FTIR). 14 figures.

  4. Electrochemical thinning of silicon

    DOEpatents

    Medernach, John W.

    1994-01-01

    Porous semiconducting material, e.g. silicon, is formed by electrochemical treatment of a specimen in hydrofluoric acid, using the specimen as anode. Before the treatment, the specimen can be masked. The porous material is then etched with a caustic solution or is oxidized, depending of the kind of structure desired, e.g. a thinned specimen, a specimen, a patterned thinned specimen, a specimen with insulated electrical conduits, and so on. Thinned silicon specimen can be subjected to tests, such as measurement of interstitial oxygen by Fourier transform infra-red spectroscopy (FTIR).

  5. Electrochemical incineration of wastes

    NASA Technical Reports Server (NTRS)

    Kaba, L.; Hitchens, G. D.; Bockris, J. O'M.

    1989-01-01

    A low temperature electrolysis process has been developed for the treatment of solid waste material and urine. Experiments are described in which organic materials are oxidized directly at the surface of an electrode. Also, hypochlorite is generated electrochemically from chloride component of urine. Hypochlorite can act as a strong oxidizing agent in solution. The oxidation takes place at 30-60 C and the gaseous products from the anodic reaction are carbon dioxide, nitrogen, oxygen. Hydrogen is formed at the cathode. Carbon monoxide, and nitrogen oxides and methane were not detected in the off gases. Chlorine was evolved at the anode in relatively low amounts.

  6. Remote electrochemical sensor

    DOEpatents

    Wang, J.; Olsen, K.; Larson, D.

    1997-10-14

    An electrochemical sensor is described for remote detection, particularly useful for metal contaminants and organic or other compounds. The sensor circumvents technical difficulties that previously prevented in-situ remote operations. The microelectrode, connected to a long communications cable, allows convenient measurements of the element or compound at timed and frequent intervals and instrument/sample distances of ten feet to more than 100 feet. The sensor is useful for both downhole groundwater monitoring and in-situ water (e.g., shipboard seawater) analysis. 21 figs.

  7. Clinical specular microscopy

    SciTech Connect

    Hirst, L.W.; Laing, R.A.

    1987-01-01

    This book provides the general ophthalmologist with a guide to the clinical applications of specular microscopy. Important material is included on laser injury, cataract surgery, corneal transplants, glaucoma, uveitis, and trauma.

  8. Photothermal imaging scanning microscopy

    DOEpatents

    Chinn, Diane; Stolz, Christopher J.; Wu, Zhouling; Huber, Robert; Weinzapfel, Carolyn

    2006-07-11

    Photothermal Imaging Scanning Microscopy produces a rapid, thermal-based, non-destructive characterization apparatus. Also, a photothermal characterization method of surface and subsurface features includes micron and nanoscale spatial resolution of meter-sized optical materials.

  9. Electrochemical photovoltaic cells and electrodes

    DOEpatents

    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.

  10. Electrochemically Programmable Plasmonic Antennas.

    PubMed

    Dong, Shi; Zhang, Kai; Yu, Zhiping; Fan, Jonathan A

    2016-07-26

    Plasmonic antennas are building blocks in advanced nano-optical systems due to their ability to tailor optical response based on their geometry. We propose an electrochemical approach to program the optical properties of dipole antennas in a scalable, fast, and energy-efficient manner. These antennas comprise two arms, one serving as an anode and the other a cathode, separated by a solid electrolyte. As a voltage is applied between the antenna arms, a conductive filament either grows or dissolves within the electrolyte, modifying the antenna load. We probe the dynamics of stochastic filament formation and their effects on plasmonic mode programming using a combination of three-dimensional optical and electronic simulations. In particular, we identify device operation regimes in which the charge-transfer plasmon mode can be programmed to be "on" or "off." We also identify, unexpectedly, a strong correlation between DC filament resistance and charge-transfer plasmon mode frequency that is insensitive to the detailed filament morphology. We envision that the scalability of our electrochemical platform can generalize to large-area reconfigurable metamaterials and metasurfaces for on-chip and free-space applications.

  11. Electrochemically regenerable carbon dioxide absorber

    NASA Technical Reports Server (NTRS)

    Woods, R. R.; Marshall, R. D.; Schubert, F. H.; Heppner, D. B.

    1979-01-01

    Preliminary designs were generated for two electrochemically regenerable carbon dioxide absorber concepts. Initially, an electrochemically regenerable absorption bed concept was designed. This concept incorporated the required electrochemical regeneration components in the absorber design, permitting the absorbent to be regenerated within the absorption bed. This hardware was identified as the electrochemical absorber hardware. The second hardware concept separated the functional components of the regeneration and absorption process. This design approach minimized the extravehicular activity component volume by eliminating regeneration hardware components within the absorber. The electrochemical absorber hardware was extensively characterized for major operating parameters such as inlet carbon dioxide partial pressure, process air flow rate, operational pressure, inlet relative humidity, regeneration current density and absorption/regeneration cycle endurance testing.

  12. Electrochemical biosensors for hormone analyses.

    PubMed

    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.

  13. Intermittent contact hydration scanning probe microscopy.

    PubMed

    Aloisi, G; Bacci, F; Carlà, M; Dolci, D

    2010-07-01

    Hydration scanning probe microscopy is a technique similar to scanning tunneling microscopy, in which the probe current, sustained by the slight surface conduction of a thin hydration layer covering an insulating support surface, is essentially electrochemical in nature instead of electronic tunneling. Such a technique allows the imaging of a great variety of samples, including insulators, provided that they are hydrophilic, as well as the study of molecular samples of biological interest (such as DNA) fixed on a suitable supporting surface. The main problem to obtain stable and reproducible images comes from the very critical determination of the operating conditions under which the probe-hydration layer interaction does not lead to the formation of a relatively large water meniscus. It has been suggested that this issue can be removed by adding a high frequency oscillation to the probe movement, as in tapping atomic force microscopy. Meniscus formation and breakup have been investigated in order to determine the best values for the amplitude and the frequency of the oscillation. Results obtained in this mode are discussed in comparison with the usual continuous contact mode.

  14. Zinc oxide nanostructures for electrochemical cortisol biosensing

    NASA Astrophysics Data System (ADS)

    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.

  15. Electrochemical characterization of aminated acrylic conducting polymer

    SciTech Connect

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

    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.

  16. Tough germanium nanoparticles under electrochemical cycling.

    PubMed

    Liang, Wentao; Yang, Hui; Fan, Feifei; Liu, Yang; Liu, Xiao Hua; Huang, Jian Yu; Zhu, Ting; Zhang, Sulin

    2013-04-23

    Mechanical degradation of the electrode materials during electrochemical cycling remains a serious issue that critically limits the capacity retention and cyclability of rechargeable lithium-ion batteries. Here we report the highly reversible expansion and contraction of germanium nanoparticles under lithiation-delithiation cycling with in situ transmission electron microscopy (TEM). During multiple cycles to the full capacity, the germanium nanoparticles remained robust without any visible cracking despite ∼260% volume changes, in contrast to the size-dependent fracture of silicon nanoparticles upon the first lithiation. The comparative in situ TEM study of fragile silicon nanoparticles suggests that the tough behavior of germanium nanoparticles can be attributed to the weak anisotropy of the lithiation strain at the reaction front. The tough germanium nanoparticles offer substantial potential for the development of durable, high-capacity, and high-rate anodes for advanced lithium-ion batteries.

  17. Electrochemical hydrogen Storage Systems

    SciTech Connect

    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 described in the

  18. Electrochemical sensor for monitoring electrochemical potentials of fuel cell components

    DOEpatents

    Kunz, Harold R.; Breault, Richard D.

    1993-01-01

    An electrochemical sensor comprised of wires, a sheath, and a conduit can be utilized to monitor fuel cell component electric potentials during fuel cell shut down or steady state. The electrochemical sensor contacts an electrolyte reservoir plate such that the conduit wicks electrolyte through capillary action to the wires to provide water necessary for the electrolysis reaction which occurs thereon. A voltage is applied across the wires of the electrochemical sensor until hydrogen evolution occurs at the surface of one of the wires, thereby forming a hydrogen reference electrode. The voltage of the fuel cell component is then determined with relation to the hydrogen reference electrode.

  19. Nonlinear vibrational microscopy

    DOEpatents

    Holtom, Gary R.; Xie, Xiaoliang Sunney; Zumbusch, Andreas

    2000-01-01

    The present invention is a method and apparatus for microscopic vibrational imaging using coherent Anti-Stokes Raman Scattering or Sum Frequency Generation. Microscopic imaging with a vibrational spectroscopic contrast is achieved by generating signals in a nonlinear optical process and spatially resolved detection of the signals. The spatial resolution is attained by minimizing the spot size of the optical interrogation beams on the sample. Minimizing the spot size relies upon a. directing at least two substantially co-axial laser beams (interrogation beams) through a microscope objective providing a focal spot on the sample; b. collecting a signal beam together with a residual beam from the at least two co-axial laser beams after passing through the sample; c. removing the residual beam; and d. detecting the signal beam thereby creating said pixel. The method has significantly higher spatial resolution then IR microscopy and higher sensitivity than spontaneous Raman microscopy with much lower average excitation powers. CARS and SFG microscopy does not rely on the presence of fluorophores, but retains the resolution and three-dimensional sectioning capability of confocal and two-photon fluorescence microscopy. Complementary to these techniques, CARS and SFG microscopy provides a contrast mechanism based on vibrational spectroscopy. This vibrational contrast mechanism, combined with an unprecedented high sensitivity at a tolerable laser power level, provides a new approach for microscopic investigations of chemical and biological samples.

  20. Optical imaging. Expansion microscopy.

    PubMed

    Chen, Fei; Tillberg, Paul W; Boyden, Edward S

    2015-01-30

    In optical microscopy, fine structural details are resolved by using refraction to magnify images of a specimen. We discovered that by synthesizing a swellable polymer network within a specimen, it can be physically expanded, resulting in physical magnification. By covalently anchoring specific labels located within the specimen directly to the polymer network, labels spaced closer than the optical diffraction limit can be isotropically separated and optically resolved, a process we call expansion microscopy (ExM). Thus, this process can be used to perform scalable superresolution microscopy with diffraction-limited microscopes. We demonstrate ExM with apparent ~70-nanometer lateral resolution in both cultured cells and brain tissue, performing three-color superresolution imaging of ~10(7) cubic micrometers of the mouse hippocampus with a conventional confocal microscope.

  1. Electrochemical storage cell

    SciTech Connect

    Hartmann, B.; Kleinschmager, H.

    1980-12-16

    An electrochemical storage cell or battery with an anode space for an alkali metal as the anolyte and with a cathode space for a sulfur-containing catholyte substance, which are separated from each other by an alkali-ion-conducting solid electrolyte and are confined by a cell wall of metal, particularly of a light metal or steel is described. Long-life corrosion protection of the metal cell wall is provided by a protective layer by applying to at least that part of the metal cell wall in contact with the catholyte substance, a foil of corrosion-resistant material 0.01 to 0.2 mm thick by means of a conductive adhesive which retains its adhesive properties at operating temperatures.

  2. Electrochemical storage cell

    SciTech Connect

    Langpape, R.

    1984-06-05

    The invention relates to an electrochemical storage cell on the basis of alkali metal and chalcogen, particularly sodium and sulfur. The storage cell has an anode space for receiving the anolyte and a cathode space for receiving the catholyte. The two spaces are separated from each other by a cup-shaped solid electrolyte. The solid electrolyte is surrounded in the region of the anode space by a capillary structure over the entire length. The capillary structure has at least one widened portion which is formed by an outward-pointing bulge of the capillary structure. The widened portion extends over the entire length of the capillary structure. Each widened portion is traversed in its interior by a canal. The cylinder surface of this canal is formed by a metal screen. The entrance opening of this canal is directly adjacent to the exit opening of a supply container for the sodium.

  3. Fast electrochemical actuator

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    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.

  4. Electrochemical cell design

    DOEpatents

    Arntzen, John D.

    1978-01-01

    An electrochemical cell includes two outer electrodes and a central electrode of opposite polarity, all nested within a housing having two symmetrical halves which together form an offset configuration. The outer electrodes are nested within raised portions within the side walls of each housing half while the central electrode sealingly engages the perimetric margins of the side-wall internal surfaces. Suitable interelectrode separators and electrical insulating material electrically isolate the central electrode from the housing and the outer electrodes. The outer electrodes are electrically connected to the internal surfaces of the cell housing to provide current collection. The nested structure minimizes void volume that would otherwise be filled with gas or heavy electrolyte and also provides perimetric edge surfaces for sealing and supporting at the outer margins of frangible interelectrode separator layers.

  5. Electrochemical catalyst recovery method

    DOEpatents

    Silva, Laura J.; Bray, Lane A.

    1995-01-01

    A method of recovering catalyst material from latent catalyst material solids includes: a) combining latent catalyst material solids with a liquid acid anolyte solution and a redox material which is soluble in the acid anolyte solution to form a mixture; b) electrochemically oxidizing the redox material within the mixture into a dissolved oxidant, the oxidant having a potential for oxidation which is effectively higher than that of the latent catalyst material; c) reacting the oxidant with the latent catalyst material to oxidize the latent catalyst material into at least one oxidized catalyst species which is soluble within the mixture and to reduce the oxidant back into dissolved redox material; and d) recovering catalyst material from the oxidized catalyst species of the mixture. The invention is expected to be particularly useful in recovering spent catalyst material from petroleum hydroprocessing reaction waste products having adhered sulfides, carbon, hydrocarbons, and undesired metals, and as well as in other industrial applications.

  6. Electrochemical catalyst recovery method

    DOEpatents

    Silva, L.J.; Bray, L.A.

    1995-05-30

    A method of recovering catalyst material from latent catalyst material solids includes: (a) combining latent catalyst material solids with a liquid acid anolyte solution and a redox material which is soluble in the acid anolyte solution to form a mixture; (b) electrochemically oxidizing the redox material within the mixture into a dissolved oxidant, the oxidant having a potential for oxidation which is effectively higher than that of the latent catalyst material; (c) reacting the oxidant with the latent catalyst material to oxidize the latent catalyst material into at least one oxidized catalyst species which is soluble within the mixture and to reduce the oxidant back into dissolved redox material; and (d) recovering catalyst material from the oxidized catalyst species of the mixture. The invention is expected to be particularly useful in recovering spent catalyst material from petroleum hydroprocessing reaction waste products having adhered sulfides, carbon, hydrocarbons, and undesired metals, and as well as in other industrial applications. 3 figs.

  7. Electrochemical Hydrogen Compressor

    SciTech Connect

    Lipp, Ludwig

    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).

  8. Process for electrochemically gasifying coal

    DOEpatents

    Botts, T.E.; Powell, J.R.

    1985-10-25

    A process is claimed 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. 7 figs.

  9. Renewable-reagent electrochemical sensor

    DOEpatents

    Wang, Joseph; Olsen, Khris B.

    1999-01-01

    A new electrochemical probe(s) design allowing for continuous (renewable) reagent delivery. The probe comprises an integrated membrane-sampling/electrochemical sensor that prevents interferences from surface-active materials and greatly extends the linear range. The probe(s) is useful for remote or laboratory-based monitoring in connection with microdialysis sampling and electrochemical measurements of metals and organic compounds that are not readily detected in the absence of reacting with the compound. Also disclosed is a method of using the probe(s).

  10. Renewable-reagent electrochemical sensor

    DOEpatents

    Wang, J.; Olsen, K.B.

    1999-08-24

    A new electrochemical probe(s) design allowing for continuous (renewable) reagent delivery is described. The probe comprises an integrated membrane sampling/electrochemical sensor that prevents interferences from surface-active materials and greatly extends the linear range. The probe(s) is useful for remote or laboratory-based monitoring in connection with microdialysis sampling and electrochemical measurements of metals and organic compounds that are not readily detected in the absence of reacting with the compound. Also disclosed is a method of using the probe(s). 19 figs.

  11. Light microscopy digital imaging.

    PubMed

    Joubert, James; Sharma, Deepak

    2011-10-01

    This unit presents an overview of digital imaging hardware used in light microscopy. CMOS, CCD, and EMCCDs are the primary sensors used. The strengths and weaknesses of each define the primary applications for these sensors. Sensor architecture and formats are also reviewed. Color camera design strategies and sensor window cleaning are also described in the unit.

  12. Video Telescope Operating Microscopy.

    PubMed

    Divers, Stephen J

    2015-09-01

    Exotic pet veterinarians frequently have to operate on small animals, and magnification is commonly used. Existing endoscopy equipment can be used with a mechanical arm and telescope to enable video telescope operating microscopy. The additional equipment items and their specifics are described, and several case examples are provided.

  13. Scanning ultrafast electron microscopy.

    PubMed

    Yang, Ding-Shyue; Mohammed, Omar F; Zewail, Ahmed H

    2010-08-24

    Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability.

  14. Photoacoustic computed microscopy

    PubMed Central

    Yao, Lei; Xi, Lei; Jiang, Huabei

    2014-01-01

    Photoacoustic microscopy (PAM) is emerging as a powerful technique for imaging microvasculature at depths beyond the ~1 mm depth limit associated with confocal microscopy, two-photon microscopy and optical coherence tomography. PAM, however, is currently qualitative in nature and cannot quantitatively measure important functional parameters including oxyhemoglobin (HbO2), deoxyhemoglobin (HbR), oxygen saturation (sO2), blood flow (BF) and rate of oxygen metabolism (MRO2). Here we describe a new photoacoustic microscopic method, termed photoacoustic computed microscopy (PACM) that combines current PAM technique with a model-based inverse reconstruction algorithm. We evaluate the PACM approach using tissue-mimicking phantoms and demonstrate its in vivo imaging ability of quantifying HbO2, HbR, sO2, cerebral BF and cerebral MRO2 at the small vessel level in a rodent model. This new technique provides a unique tool for neuroscience research and for visualizing microvasculature dynamics involved in tumor angiogenesis and in inflammatory joint diseases. PMID:24828539

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

    NASA Astrophysics Data System (ADS)

    Huy, Tran Quang; Hanh, Nguyen Thi Hong; Van Chung, Pham; Anh, Dang Duc; Nga, Phan Thi; Tuan, Mai Anh

    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.

  16. Electrochemical biofilm control: A review

    PubMed Central

    Sultana, Sujala T; Babauta, Jerome T; Beyenal, Haluk

    2015-01-01

    One of the methods of controlling biofilms that has widely been discussed in the literature is to apply a potential or electrical current to a metal surface on which the biofilm is growing. Although electrochemical biofilm control has been studied for decades, the literature is often conflicting, as is detailed in this review. The goals of this review are to (1) present the current status of knowledge regarding electrochemical biofilm control, (2) establish a basis for a fundamental definition of electrochemical biofilm control and requirements for studying it, (3) discuss current proposed mechanisms, and (4) introduce future directions in the field. It is expected that the review will provide researchers with guidelines on comparing data sets across the literature and generating comparable data sets. The authors believe that, with the correct design, electrochemical biofilm control has great potential for industrial use. PMID:26592420

  17. Fabrication of luminescent SrWO{sub 4} thin films by a novel electrochemical method

    SciTech Connect

    Chen Lianping Gao Yuanhong

    2007-10-02

    Highly crystallized SrWO{sub 4} thin films with single scheelite structure were prepared within 60 min by a cell electrochemical method. X-ray diffraction analysis shows that SrWO{sub 4} thin films have a tetragonal structure. Scanning electron microscopy examinations reveal that SrWO{sub 4} grains grow well in tetragonal tapers and grains like flowers or bunches, which can usually form by using the electrolysis electrochemical method, have disappeared under cell electrochemical conditions. X-ray photoelectron spectra and energy dispersive X-ray microanalysis examinations demonstrate that the composition of the film is consistent with its stoichiometry. These SrWO{sub 4} films show a single blue emission peak (located at 460 nm) using an excitation wave of 230 nm. The speed of cell electrochemical method can be controlled by changing temperature. The optimum treatment temperature is about 50-60 deg. C.

  18. Imaging Local Electric Field Distribution by Plasmonic Impedance Microscopy.

    PubMed

    Wang, Yixian; Shan, Xiaonan; Wang, Shaopeng; Tao, Nongjian; Blanchard, Pierre-Yves; Hu, Keke; Mirkin, Michael V

    2016-02-02

    We report on imaging of local electric field on an electrode surface with plasmonic electrochemical impedance microscopy (P-EIM). The local electric field is created by putting an electrode inside a micropipet positioned over the electrode and applying a voltage between the two electrodes. We show that the distribution of the surface charge as well as the local electric field at the electrode surface can be imaged with P-EIM. The spatial distribution and the dependence of the local charge density and electric field on the distance between the micropipet and the surface are measured, and the results are compared with the finite element calculations. The work also demonstrates the possibility of integrating plasmonic imaging with scanning ion conductance microscopy (SICM) and other scanning probe microscopies.

  19. Size-controlled electrochemical growth of PbS nanostructures into electrochemically patterned self-assembled monolayers.

    PubMed

    Nişancı, Fatma Bayrakçeken; Demir, Ümit

    2012-06-05

    1-Hexadecanethiol self-assembled monolayers (HDT SAMs) on Au(111) were used as a molecular resist to fabricate nanosized patterns by electrochemical reductive partial desorption for subsequent electrodeposition of PbS from the same solution simultaneously. The influences of potential steps of variable pulse width and amplitude on the size and the number of patterns were investigated. The kinetics of pattern formation by reductive desorption appears to be instantaneous according to chronoamperometric and morphological investigations. PbS structures were deposited electrochemically into the patterns on HDT SAMs by a combined electrochemical technique, based on the codeposition from the same saturated PbS solution at the underpotential deposition of Pb and S. Scanning tunneling microscopy measurements showed that all of the PbS deposits were disk shaped and uniformly distributed on Au(111) surfaces. Preliminary results indicated that the diameter and the density of PbS deposits can be controlled by controlling the pulse width and amplitude of potential applied at the reductive removal stage of HDT SAMs and the deposition time during the electrochemical deposition step.

  20. Supported liquid membrane electrochemical separators

    DOEpatents

    Pemsler, J. Paul; Dempsey, Michael D.

    1986-01-01

    Supported liquid membrane separators improve the flexibility, efficiency and service life of electrochemical cells for a variety of applications. In the field of electrochemical storage, an alkaline secondary battery with improved service life is described in which a supported liquid membrane is interposed between the positive and negative electrodes. The supported liquid membranes of this invention can be used in energy production and storage systems, electrosynthesis systems, and in systems for the electrowinning and electrorefining of metals.

  1. Electrochemical Hydrogen Compressor

    SciTech Connect

    David P. Bloomfield; Brian S. MacKenzie

    2006-05-01

    The Electrochemical Hydrogen Compressor EHC was evaluated against DOE applications for compressing hydrogen at automobile filling stations, in future hydrogen pipelines and as a commercial replacement for conventional diaphragm hydrogen compressors. It was also evaluated as a modular replacement for the compressors used in petrochemical refineries. If the EHC can be made inexpensive, reliable and long lived then it can satisfy all these applications save pipelines where the requirements for platinum catalyst exceeds the annual world production. The research performed did not completely investigate Molybdenum as a hydrogen anode or cathode, it did show that photoetched 316 stainless steel is inadequate for an EHC. It also showed that: molybdenum bipolar plates, photochemical etching processes, and Gortex Teflon seals are too costly for a commercial EHC. The use of carbon paper in combination with a perforated thin metal electrode demonstrated adequate anode support strength, but is suspect in promoting galvanic corrosion. The nature of the corrosion mechanisms are not well understood, but locally high potentials within the unit cell package are probably involved. The program produced a design with an extraordinary high cell pitch, and a very low part count. This is one of the promising aspects of the redesigned EHC. The development and successful demonstration of the hydraulic cathode is also important. The problem of corrosion resistant metal bipolar plates is vital to the development of an inexpensive, commercial PEM fuel cell. Our research suggests that there is more to the corrosion process in fuel cells and electrochemical compressors than simple, steady state, galvanic stability. It is an important area for scientific investigation. The experiments and analysis conducted lead to several recommended future research directions. First, we need a better understanding of the corrosion mechanisms involved. The diagnosis of experimental cells with titration to

  2. Nanoparticle shape evolution and proximity effects during tip-induced electrochemical processes

    DOE PAGES

    Yang, Sangmo; Paranthaman, Mariappan Parans; Noh, Tae Won; ...

    2016-01-08

    The voltage spectroscopies in scanning probe microscopy (SPM) techniques are widely used to investigate the electrochemical processes in nanoscale volumes, which are important for current key applications, such as batteries, fuel cells, catalysts, and memristors. The spectroscopic measurements are commonly performed on a grid of multiple points to yield spatially resolved maps of reversible and irreversible electrochemical functionalities. Hence, the spacing between measurement points is an important parameter to be considered, especially for irreversible electrochemical processes. Here, we report nonlocal electrochemical dynamics in chains of Ag particles fabricated by the SPM tip on a silver ion solid electrolyte. When themore » grid spacing is small compared with the size of the formed Ag particles, anomalous chains of unequally sized particles with double periodicity evolve. This behavior is ascribed to a proximity effect during the tip-induced electrochemical process, specifically, size-dependent silver particle growth following the contact between the particles. In addition, fractal shape evolution of the formed Ag structures indicates that the growth-limiting process changes from Ag+/Ag redox reaction to Ag+-ion diffusion with the increase in the applied voltage and pulse duration. Our study shows that characteristic shapes of the electrochemical products are good indicators for determining the underlying growth-limiting process, and emergence of complex phenomena during spectroscopic mapping of electrochemical functionalities.« less

  3. Nanoparticle shape evolution and proximity effects during tip-induced electrochemical processes

    SciTech Connect

    Yang, Sangmo; Paranthaman, Mariappan Parans; Noh, Tae Won; Kalinin, Sergei V.; Strelcov, Evgheni

    2016-01-08

    The voltage spectroscopies in scanning probe microscopy (SPM) techniques are widely used to investigate the electrochemical processes in nanoscale volumes, which are important for current key applications, such as batteries, fuel cells, catalysts, and memristors. The spectroscopic measurements are commonly performed on a grid of multiple points to yield spatially resolved maps of reversible and irreversible electrochemical functionalities. Hence, the spacing between measurement points is an important parameter to be considered, especially for irreversible electrochemical processes. Here, we report nonlocal electrochemical dynamics in chains of Ag particles fabricated by the SPM tip on a silver ion solid electrolyte. When the grid spacing is small compared with the size of the formed Ag particles, anomalous chains of unequally sized particles with double periodicity evolve. This behavior is ascribed to a proximity effect during the tip-induced electrochemical process, specifically, size-dependent silver particle growth following the contact between the particles. In addition, fractal shape evolution of the formed Ag structures indicates that the growth-limiting process changes from Ag+/Ag redox reaction to Ag+-ion diffusion with the increase in the applied voltage and pulse duration. Our study shows that characteristic shapes of the electrochemical products are good indicators for determining the underlying growth-limiting process, and emergence of complex phenomena during spectroscopic mapping of electrochemical functionalities.

  4. Characterization of Electrochemically Generated Silver

    NASA Technical Reports Server (NTRS)

    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 (<500 ppb) have been shown to kill bacteria in water systems and keep it safe for potability. 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.

  5. Antitumor effects of electrochemical treatment

    PubMed Central

    González, Maraelys Morales; Zamora, Lisset Ortíz; Cabrales, Luis Enrique Bergues; Sierra González, Gustavo Victoriano; de Oliveira, Luciana Oliveira; Zanella, Rodrigo; Buzaid, Antonio Carlos; Parise, Orlando; Brito, Luciana Macedo; Teixeira, Cesar Augusto Antunes; Gomes, Marina das Neves; Moreno, Gleyce; Feo da Veiga, Venicio; Telló, Marcos; Holandino, Carla

    2013-01-01

    Electrochemical treatment is an alternative modality for tumor treatment based on the application of a low intensity direct electric current to the tumor tissue through two or more platinum electrodes placed within the tumor zone or in the surrounding areas. This treatment is noted for its great effectiveness, minimal invasiveness and local effect. Several studies have been conducted worldwide to evaluate the antitumoral effect of this therapy. In all these studies a variety of biochemical and physiological responses of tumors to the applied treatment have been obtained. By this reason, researchers have suggested various mechanisms to explain how direct electric current destroys tumor cells. Although, it is generally accepted this treatment induces electrolysis, electroosmosis and electroporation in tumoral tissues. However, action mechanism of this alternative modality on the tumor tissue is not well understood. Although the principle of Electrochemical treatment is simple, a standardized method is not yet available. The mechanism by which Electrochemical treatment affects tumor growth and survival may represent more complex process. The present work analyzes the latest and most important research done on the electrochemical treatment of tumors. We conclude with our point of view about the destruction mechanism features of this alternative therapy. Also, we suggest some mechanisms and strategies from the thermodynamic point of view for this therapy. In the area of Electrochemical treatment of cancer this tool has been exploited very little and much work remains to be done. Electrochemical treatment constitutes a good therapeutic option for patients that have failed the conventional oncology methods. PMID:23592904

  6. Polarized Light Microscopy

    NASA Technical Reports Server (NTRS)

    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

  7. Surface Modification of Nitinol by Chemical and Electrochemical Etching

    NASA Astrophysics Data System (ADS)

    Yang, Zhendi; Wei, Xiaojin; Cao, Peng; Gao, Wei

    2013-07-01

    In this paper, Nitinol, an equiatomic binary alloy of nickel and titanium, was surface modified for its potential biomedical applications by chemical and electrochemical etching. The main objective of the surface modification is to reduce the nickel content on the surface of Nitinol and simultaneously to a rough surface microstructure. As a result, better biocompatibility and better cell attachment would be achieved. The effect of the etching parameters was investigated, using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDX) and X-ray photoelectron spectrometry (XPS). The corrosion property of modified Nitinol surfaces was investigated by electrochemical work station. After etching, the Ni content in the surface layer has been reduced and the oxidation of Ti has been enhanced.

  8. Quantitative deconvolution microscopy.

    PubMed

    Goodwin, Paul C

    2014-01-01

    The light microscope is an essential tool for the study of cells, organelles, biomolecules, and subcellular dynamics. A paradox exists in microscopy whereby the higher the needed lateral resolution, the more the image is degraded by out-of-focus information. This creates a significant need to generate axial contrast whenever high lateral resolution is required. One strategy for generating contrast is to measure or model the optical properties of the microscope and to use that model to algorithmically reverse some of the consequences of high-resolution imaging. Deconvolution microscopy implements model-based methods to enable the full diffraction-limited resolution of the microscope to be exploited even in complex and living specimens.

  9. Electrochemical polishing of notches

    DOEpatents

    Kephart, Alan R.; Alberts, Alfred H.

    1989-01-01

    An apparatus and method are disclosed for the selective electrochemical polishing of a lateral tip of a deep longitudinal notch in a work piece used to test crack initiation properties of materials. A DC power source is connected to the work piece and to an electrode disposed laterally along the distal end of an insulated body which is inserted in the longitudinal notch. The electrode and distal end of the body are disposed along the tip of the notch, but are spaced from the notch so as to provide a lateral passage for an electrolyte. The electrolyte is circulated through the passage so that the electrolyte only contacts the work piece adjacent the passage. Conveniently, the electrolyte is circulated by use of an inlet tube and an outlet tube provided at opposite ends of the passage. These tubes are preferably detachably located adjacent the ends of the passage and suitable seals are provided. A holding device including arms to which the tubes are attached is conveniently used to rapidly and easily locate the test specimen with the passage aligned with the tubes. The electrode is preferably a wire which is located in grooves along the distal end of the insulated body and up one side of the body or a plastic sheath insulated thin metal strip.

  10. Electrochemical polishing of notches

    DOEpatents

    Kephart, A.R.; Alberts, A.H.

    1989-02-21

    An apparatus and method are disclosed for the selective electrochemical polishing of a lateral tip of a deep longitudinal notch in a work piece used to test crack initiation properties of materials. A DC power source is connected to the work piece and to an electrode disposed laterally along the distal end of an insulated body which is inserted in the longitudinal notch. The electrode and distal end of the body are disposed along the tip of the notch, but are spaced from the notch so as to provide a lateral passage for an electrolyte. The electrolyte is circulated through the passage so that the electrolyte only contacts the work piece adjacent the passage. Conveniently, the electrolyte is circulated by use of an inlet tube and an outlet tube provided at opposite ends of the passage. These tubes are preferably detachably located adjacent the ends of the passage and suitable seals are provided. A holding device including arms to which the tubes are attached is conveniently used to rapidly and easily locate the test specimen with the passage aligned with the tubes. The electrode is preferably a wire which is located in grooves along the distal end of the insulated body and up one side of the body or a plastic sheath insulated thin metal strip. 4 figs.

  11. Electrochemical incineration of wastes

    NASA Technical Reports Server (NTRS)

    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.

  12. Electrochemical Ion Transfer with Thin Films of Poly(3-octylthiophene).

    PubMed

    Cuartero, Maria; Acres, Robert G; De Marco, Roland; Bakker, Eric; Crespo, Gastón A

    2016-07-05

    We report on the limiting conditions for ion-transfer voltammetry between an ion-exchanger doped and plasticized poly(vinyl chloride) (PVC) membrane and an electrolyte solution that was triggered via the oxidation of a poly(3-octylthiophene) (POT) solid-contact (SC), which was unexpectedly related to the thickness of the POT SC. An electropolymerized 60 nm thick film of POT coated with a plasticized PVC membrane exhibited a significant sodium transfer voltammetric signal whereas a thicker film (180 nm) did not display a measurable level of ion transfer due to a lack of oxidation of thick POT beneath the membrane film. In contrast, this peculiar phenomenon was not observed when the POT film was in direct contact with an organic solvent-based electrolyte. This evidence is indicative of three key points: (i) the coated membrane imposes a degree of rigidity to the system, which restricts the swelling of the POT film and its concomitant p-doping; (ii) this phenomenon is exacerbated with thicker POT films due to an initial morphology (rougher comprising a network of large POT nanoparticles), which gives rise to a diminished surface area and electrochemical reactivity in the POT SC; (iii) the rate of sodium transfer is higher with a thin POT film due to a smoother surface morphology made up of a network of smaller POT nanoparticles with an increased surface area and electrochemical reactivity. A variety of techniques including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), ellipsometry, scanning electron microscopy (SEM), atomic force microscopy (AFM), and synchrotron radiation-X-ray photoelectron spectroscopy (SR-XPS) were used to elucidate the mechanism of the POT thickness/POT surface roughness dependency on the electrochemical reactivity of the PVC/POT SC system.

  13. Ion photon emission microscopy

    NASA Astrophysics Data System (ADS)

    Rossi, P.; Doyle, B. L.; Banks, J. C.; Battistella, A.; Gennaro, G.; McDaniel, F. D.; Mellon, M.; Vittone, E.; Vizkelethy, G.; Wing, N. D.

    2003-09-01

    A new ion-induced emission microscopy has been invented and demonstrated, which is called ion photon emission microscopy (IPEM). It employs a low current, broad ion beam impinging on a sample, previously coated or simply covered with a few microns of a fast, highly efficient phosphor layer. The light produced at the single ion impact point is collected with an optical microscope and projected at high magnification onto a single photon position sensitive detector (PSD). This allows maps of the ion strike effects to be produced, effectively removing the need for a microbeam. Irradiation in air and even the use of alpha particle sources with no accelerator are possible. Potential applications include ion beam induced charge collection studies of semiconducting and insulating materials, single event upset studies on microchips and even biological cells in radiobiological effectiveness experiments. We describe the IPEM setup, including a 60× OM-40 microscope with a 1.5 mm hole for the beam transmission and a Quantar PSD with 60 μm pixel. Bicron plastic scintillator blades of 10 μm were chosen as a phosphor for their nanosecond time resolution, homogeneity, utility and commercial availability. The results given in this paper are for a prototype IPEM system. They indicate a resolution of ˜12 μm, the presence of a spatial halo and a He-ion efficiency of ˜20%. This marks the first time that nuclear microscopy has been performed with a radioactive source.

  14. Multimodal multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Légaré, François; Pfeffer, Christian P.; Ganikhanov, Feruz

    2009-02-01

    Multiphoton microscopy is a powerful technique for high spatial resolution thick tissue imaging. In its simple version, it uses a high repetition rate femtosecond oscillator laser source focussed and scanned across biological sample that contains fluorophores. However, not every biological structure is inherently fluorescent or can be stained without causing biochemical changes. To circumvent these limitations, other non-invasive nonlinear optical imaging approaches are currently being developed and investigated with regard to different applications. These techniques are: (1) second harmonic generation (SHG), (2) third harmonic generation (THG), and (3) coherent anti-Stokes Raman scattering (CARS) microscopy. The main advantage of the above mentioned techniques is that they derive their imaging contrast from optical nonlinearities that do not involve fluorescence process. As a particular application example we investigated collagen arrays. We show that combining SHG-THG-CARS onto a single imaging platform provides complementary information about the sub-micron architecture of the tissue. SHG microscopy reveals the fibrillar architecture of collagen arrays and confirm a rather high degree of heterogeneity of χ(2) within the focal volume, THG highlights the boundaries between the collagen sheets, and CH2 spectroscopic contrast with CARS.

  15. Structure, Electronic Properties, and Electrochemical Behavior of a Boron-Doped Diamond/Quartz Optically Transparent Electrode.

    PubMed

    Wächter, Naihara; Munson, Catherine; Jarošová, Romana; Berkun, Isil; Hogan, Timothy; Rocha-Filho, Romeu C; Swain, Greg M

    2016-05-31

    The morphology, microstructure, chemistry, electronic properties, and electrochemical behavior of a boron-doped nanocrystalline diamond (BDD) thin film grown on quartz were evaluated. Diamond optically transparent electrodes (OTEs) are useful for transmission spectroelectrochemical measurements, offering excellent stability during anodic and cathodic polarization and exposure to a variety of chemical environments. We report on the characterization of a BDD OTE by atomic force microscopy, optical spectroscopy, Raman spectroscopic mapping, alternating-current Hall effect measurements, X-ray photoelectron spectroscopy, and electrochemical methods. The results reported herein provide the first comprehensive study of the relationship between the physical and chemical structure and electronic properties of a diamond OTE and the electrode's electrochemical activity.

  16. Electrochemical performance and biosensor application of TiO2 nanotube arrays with mesoporous structures constructed by chemical etching.

    PubMed

    Wang, Jinwen; Xu, Guangqing; Zhang, Xu; Lv, Jun; Zhang, Xinyi; Zheng, Zhixiang; Wu, Yucheng

    2015-04-28

    Novel mesoporous TiO2 nanotube arrays (TiO2 NTAs) were synthesized by an anodization method combined with chemical etching in HF solution, and the electrochemical performance was studied. Glucose oxidase (GOx) was immobilized on the mesoporous TiO2 NTAs to achieve an efficient biosensor for amperometric detection of glucose. The morphology, structure, component and electrochemical performance of mesoporous TiO2 NTAs were characterized by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffractometry, X-ray photoelectron spectrometry and an electrochemical workstation, respectively. The influence of the mesoporous structure on the electrochemical performance is discussed in detail by comparing the cyclic voltammograms and electrochemical impedance spectrum of TiO2 and mesoporous TiO2 NTAs in different conditions. High electrochemical active surface area and electron transfer rate play key roles in enhancing the electrochemical performance of mesoporous TiO2 NTAs. When used as the basis of a biosensor, the amperometric response of glucose on a GOx/TiO2-0.5 NTAs electrode is linearly proportion to the glucose concentration in the range from 0.1 to 6 mM with a sensitivity of 0.954 μA mM(-1) cm(-2), which is 14.3 times that of un-etched GOx/TiO2 NTAs.

  17. Spatially-resolved mapping of history-dependent coupled electrochemical and electronical behaviors of electroresistive NiO

    DOE PAGES

    Sugiyama, Issei; Kim, Yunseok; Jesse, Stephen; ...

    2014-10-22

    Bias-induced oxygen ion dynamics underpins a broad spectrum of electroresistive and memristive phenomena in oxide materials. Although widely studied by device-level and local voltage-current spectroscopies, the relationship between electroresistive phenomena, local electrochemical behaviors, and microstructures remains elusive. Here, the interplay between history-dependent electronic transport and electrochemical phenomena in a NiO single crystalline thin film with a number of well-defined defect types is explored on the nanometer scale using an atomic force microscopy-based technique. A variety of electrochemically-active regions were observed and spatially resolved relationship between the electronic and electrochemical phenomena was revealed. The regions with pronounced electroresistive activity were furthermore » correlated with defects identified by scanning transmission electron microscopy. Using fully coupled mechanical-electrochemical modeling, we illustrate that the spatial distribution of strain plays an important role in electrochemical and electroresistive phenomena. In conclusion, these studies illustrate an approach for simultaneous mapping of the electronic and ionic transport on a single defective structure level such as dislocations or interfaces, and pave the way for creating libraries of defect-specific electrochemical responses.« less

  18. Spatially-resolved mapping of history-dependent coupled electrochemical and electronical behaviors of electroresistive NiO

    SciTech Connect

    Sugiyama, Issei; Kim, Yunseok; Jesse, Stephen; Strelcov, Evgheni; Kumar, Amit; Tselev, Alexander; Rahani, Ehasan Kabiri; Shenoy, Vivek B.; Yamamoto, Takahisa; Shibata, Naoya; Ikuhara, Yuichi; Kalinin, Sergei V.

    2014-10-22

    Bias-induced oxygen ion dynamics underpins a broad spectrum of electroresistive and memristive phenomena in oxide materials. Although widely studied by device-level and local voltage-current spectroscopies, the relationship between electroresistive phenomena, local electrochemical behaviors, and microstructures remains elusive. Here, the interplay between history-dependent electronic transport and electrochemical phenomena in a NiO single crystalline thin film with a number of well-defined defect types is explored on the nanometer scale using an atomic force microscopy-based technique. A variety of electrochemically-active regions were observed and spatially resolved relationship between the electronic and electrochemical phenomena was revealed. The regions with pronounced electroresistive activity were further correlated with defects identified by scanning transmission electron microscopy. Using fully coupled mechanical-electrochemical modeling, we illustrate that the spatial distribution of strain plays an important role in electrochemical and electroresistive phenomena. In conclusion, these studies illustrate an approach for simultaneous mapping of the electronic and ionic transport on a single defective structure level such as dislocations or interfaces, and pave the way for creating libraries of defect-specific electrochemical responses.

  19. Spatial Resolution in Scanning Electron Microscopy and Scanning Transmission Electron Microscopy Without a Specimen Vacuum Chamber.

    PubMed

    Nguyen, Kayla X; Holtz, Megan E; Richmond-Decker, Justin; Muller, David A

    2016-08-01

    A long-standing goal of electron microscopy has been the high-resolution characterization of specimens in their native environment. However, electron optics require high vacuum to maintain an unscattered and focused probe, a challenge for specimens requiring atmospheric or liquid environments. Here, we use an electron-transparent window at the base of a scanning electron microscope's objective lens to separate column vacuum from the specimen, enabling imaging under ambient conditions, without a specimen vacuum chamber. We demonstrate in-air imaging of specimens at nanoscale resolution using backscattered scanning electron microscopy (airSEM) and scanning transmission electron microscopy. We explore resolution and contrast using Monte Carlo simulations and analytical models. We find that nanometer-scale resolution can be obtained at gas path lengths up to 400 μm, although contrast drops with increasing gas path length. As the electron-transparent window scatters considerably more than gas at our operating conditions, we observe that the densities and thicknesses of the electron-transparent window are the dominant limiting factors for image contrast at lower operating voltages. By enabling a variety of detector configurations, the airSEM is applicable to a wide range of environmental experiments including the imaging of hydrated biological specimens and in situ chemical and electrochemical processes.

  20. Electrochemical Hydrogen Peroxide Generator

    NASA Technical Reports Server (NTRS)

    Tennakoon, Charles L. K.; Singh, Waheguru; Anderson, Kelvin C.

    2010-01-01

    Two-electron reduction of oxygen to produce hydrogen peroxide is a much researched topic. Most of the work has been done in the production of hydrogen peroxide in basic media, in order to address the needs of the pulp and paper industry. However, peroxides under alkaline conditions show poor stabilities and are not useful in disinfection applications. There is a need to design electrocatalysts that are stable and provide good current and energy efficiencies to produce hydrogen peroxide under acidic conditions. The innovation focuses on the in situ generation of hydrogen peroxide using an electrochemical cell having a gas diffusion electrode as the cathode (electrode connected to the negative pole of the power supply) and a platinized titanium anode. The cathode and anode compartments are separated by a readily available cation-exchange membrane (Nafion 117). The anode compartment is fed with deionized water. Generation of oxygen is the anode reaction. Protons from the anode compartment are transferred across the cation-exchange membrane to the cathode compartment by electrostatic attraction towards the negatively charged electrode. The cathode compartment is fed with oxygen. Here, hydrogen peroxide is generated by the reduction of oxygen. Water may also be generated in the cathode. A small amount of water is also transported across the membrane along with hydrated protons transported across the membrane. Generally, each proton is hydrated with 3-5 molecules. The process is unique because hydrogen peroxide is formed as a high-purity aqueous solution. Since there are no hazardous chemicals or liquids used in the process, the disinfection product can be applied directly to water, before entering a water filtration unit to disinfect the incoming water and to prevent the build up of heterotrophic bacteria, for example, in carbon based filters. The competitive advantages of this process are: 1. No consumable chemicals are needed in the process. The only raw materials

  1. Electrochemical incineration of wastes

    NASA Astrophysics Data System (ADS)

    Bhardwaj, R. C.; Sharma, D. K.; Bockris, J. Om.

    1990-08-01

    The novel technology of waste removal in space vehicles by electrochemical methods is presented to convert wastes into chemicals that can be eventually recycled. The important consideration for waste oxidation is to select a right kind of electrode (anode) material that should be stable under anodic conditions and also a poor electrocatalyst for oxygen and chlorine evolution. On the basis of long term electrolysis experiments on seven different electrodes and on the basis of total organic carbon reduced, two best electrodes were identified. The effect of redox ions on the electrolyte was studied. Though most of the experiments were done in mixtures of urine and waste, the experiments with redox couples involved 2.5 M sulfuric acid in order to avoid the precipitation of redox ions by urea. Two methods for long term electrolysis of waste were investigated: (1) the oxidation on Pt and lead dioxide electrodes using the galvanostatic methods; and (2) potentiostatic method on other electrodes. The advantage of the first method is the faster rate of oxidation. The chlorine evolution in the second method is ten times less then in the first. The accomplished research has shown that urine/feces mixtures can be oxidized to carbon dioxide and water, but current densities are low and must be improved. The perovskite and Ti4O7 coated with RuO2 are the best electrode materials found. Recent experiment with the redox agent improves the current density, however, sulphuric acid is required to keep the redox agent in solution to enhance oxidation effectively. It is desirable to reduce the use of acid and/or find substitutes.

  2. Electrochemical incineration of wastes

    NASA Technical Reports Server (NTRS)

    Bhardwaj, R. C.; Sharma, D. K.; Bockris, J. OM.

    1990-01-01

    The novel technology of waste removal in space vehicles by electrochemical methods is presented to convert wastes into chemicals that can be eventually recycled. The important consideration for waste oxidation is to select a right kind of electrode (anode) material that should be stable under anodic conditions and also a poor electrocatalyst for oxygen and chlorine evolution. On the basis of long term electrolysis experiments on seven different electrodes and on the basis of total organic carbon reduced, two best electrodes were identified. The effect of redox ions on the electrolyte was studied. Though most of the experiments were done in mixtures of urine and waste, the experiments with redox couples involved 2.5 M sulfuric acid in order to avoid the precipitation of redox ions by urea. Two methods for long term electrolysis of waste were investigated: (1) the oxidation on Pt and lead dioxide electrodes using the galvanostatic methods; and (2) potentiostatic method on other electrodes. The advantage of the first method is the faster rate of oxidation. The chlorine evolution in the second method is ten times less then in the first. The accomplished research has shown that urine/feces mixtures can be oxidized to carbon dioxide and water, but current densities are low and must be improved. The perovskite and Ti4O7 coated with RuO2 are the best electrode materials found. Recent experiment with the redox agent improves the current density, however, sulphuric acid is required to keep the redox agent in solution to enhance oxidation effectively. It is desirable to reduce the use of acid and/or find substitutes.

  3. Novel nanoarchitectures for electrochemical biosensing

    NASA Astrophysics Data System (ADS)

    Archibald, Michelle M.

    Sensitive, real-time detection of biomarkers is of critical importance for rapid and accurate diagnosis of disease for point-of-care (POC) technologies. Current methods, while sensitive, do not adequately allow for POC applications due to several limitations, including complex instrumentation, high reagent consumption, and cost. We have investigated two novel nanoarchitectures, the nanocoax and the nanodendrite, as electrochemical biosensors towards the POC detection of infectious disease biomarkers to overcome these limitations. The nanocoax architecture is composed of vertically-oriented, nanoscale coaxial electrodes, with coax cores and shields serving as integrated working and counter electrodes, respectively. The dendritic structure consists of metallic nanocrystals extending from the working electrode, increasing sensor surface area. Nanocoaxial- and nanodendritic-based electrochemical sensors were fabricated and developed for the detection of bacterial toxins using an electrochemical enzyme-linked immunosorbent assay (ELISA) and differential pulse voltammetry (DPV). Proof-of-concept was demonstrated for the detection of cholera toxin (CT). Both nanoarchitectures exhibited levels of sensitivity that are comparable to the standard optical ELISA used widely in clinical applications. In addition to matching the detection profile of the standard ELISA, these electrochemical nanosensors provide a simple electrochemical readout and a miniaturized platform with multiplexing capabilities toward POC implementation. Further development as suggested in this thesis may lead to increases in sensitivity, enhancing the attractiveness of the architectures for future POC devices.

  4. Fourier plane imaging microscopy

    SciTech Connect

    Dominguez, Daniel Peralta, Luis Grave de; Alharbi, Nouf; Alhusain, Mdhaoui; Bernussi, Ayrton A.

    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.

  5. Spatial spectrograms of vibrating atomic force microscopy cantilevers coupled to sample surfaces

    SciTech Connect

    Wagner, Ryan; Raman, Arvind; Proksch, Roger

    2013-12-23

    Many advanced dynamic Atomic Force Microscopy (AFM) techniques such as contact resonance, force modulation, piezoresponse force microscopy, electrochemical strain microscopy, and AFM infrared spectroscopy exploit the dynamic response of a cantilever in contact with a sample to extract local material properties. Achieving quantitative results in these techniques usually requires the assumption of a certain shape of cantilever vibration. We present a technique that allows in-situ measurements of the vibrational shape of AFM cantilevers coupled to surfaces. This technique opens up unique approaches to nanoscale material property mapping, which are not possible with single point measurements alone.

  6. Influence of sodium chloride content in electrolyte solution on electrochemical impedance measurements of human dentin

    PubMed Central

    Eldarrat, Aziza; High, Alec; Kale, Girish

    2017-01-01

    Background: The aim of this study was to investigate the influence of sodium chloride (NaCl) content in electrolyte solution on electrochemical impedance measurements of human dentin by employing electrochemical impedance spectroscopy. Materials and Methods: Dentin samples were prepared from extracted molars. Electrochemical impedance measurements were carried out over a wide frequency range (0.01Hz-10MHz). After measurements, samples were characterized using scanning electron microscopy. Results: Electrochemical impedance measurements showed that the mean values of dentin electrical resistance were 4284, 2062, 1336, 53 and 48kΩ at different NaCl contents in electrolyte solution. One-way ANOVA test of mean values of dentin electrical resistance revealed a significant difference (P < 0.0001) as a function of NaCl content in electrolyte solution. Comparing electrical resistance values of dentin samples at 0.05% w/v and 0.9% w/v concentrations were found to be significantly different (P < 0.05 at 95% confidence level). Scanning electron microscopy revealed structure of dentin sample with intertubular dentin matrix and distribution of patent dentinal tubules. Conclusion: This in vitro study indicated, through electrochemical impedance spectroscopy measurements, that electrical resistance of dentin was affected by the concentration of NaCl in electrolyte solution. It is clear from the current study that NaCl concentration in electrolyte solution has a marked influence on dentin electrical resistance. Therefore, this baseline data need to be considered in any future study on dental samples. PMID:28348614

  7. Distance effects in electrochemical micromachining

    PubMed Central

    Xu, Lizhong; Pan, Yue; Zhao, Chuanjun

    2016-01-01

    Considering exponential dependence of currents on double-layer voltage and the feedback effect of the electrolyte resistance, a distance effect in electrochemical micromachining is found, namely that both time constant and double-layer voltage depend on the separation of electrodes. The double-layer voltage is the real voltage used in processing. Under DC voltage, the apparent voltages between two electrodes are constant for different separations, but the real voltages change with the separations. Small separations exert substantial effects on the real voltages. Accordingly, a DC-voltage small-separation electrochemical micromachining technique was proposed. The double-layer voltage drops sharply as the small separation increases. Thus, the electrochemical reactions are confined to electrode regions in very close proximity even under DC voltage. The machining precision can be significantly enhanced by reducing the voltage and separation between electrodes. With this technique, the machining of conducting materials with submicrometre precision was achieved. PMID:27581708

  8. Space Electrochemical Research and Technology

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This document contains the proceedings of NASA's fourth Space Electrochemical Research and Technology (SERT) Conference, held at the NASA Lewis Research Center on April 14-15, 1993. The objective of the conference was to assess the present status and general thrust of research and development in those areas of electrochemical technology required to enable NASA missions into the next century. The conference provided a forum for the exchange of ideas and opinions of those actively involved in the field, in order to define new opportunities for the application of electrochemical processes in future NASA missions. Papers were presented in three technical areas: advanced secondary batteries, fuel cells, and advanced concepts for space power. This document contains the papers presented.

  9. Apoptosis Evaluation by Electrochemical Techniques.

    PubMed

    Yin, Jian; Miao, Peng

    2016-03-04

    Apoptosis has close relevance to pathology, pharmacology, and toxicology. Accurate and convenient detection of apoptosis would be beneficial for biological study, clinical diagnosis, and drug development. Based on distinct features of apoptotic cells, a diversity of analytical techniques have been exploited for sensitive analysis of apoptosis, such as surface plasmon resonance, electrochemical methods, flow cytometry, and some imaging assays. Among them, the features of simplicity, easy operation, low cost, and high sensitivity make electrochemical techniques powerful tools to investigate electron-transfer processes of in vitro biological systems. In this contribution, a general overview of current knowledge on various technical approaches for apoptosis evaluation is provided. Furthermore, recently developed electrochemical biosensors for detecting apoptotic cells and their advantages over traditional methods are summarized. One of the main considerations focuses on designing the recognition elements based on various biochemical events during apoptosis.

  10. ELECTROCHEMICAL DECHLORINATIONOF 2-CHLOROBIPHENYL IN AQUEOUS SOLUTION

    EPA Science Inventory

    This paper presents electrochemical dechlorination of 2-chlorobiphenyl (2-CI BP) in aqueous environment using palladium modified granular graphite electrodes. 2-CI BP, the PCB congener that requires the highest reduction potential, was effectively dechlorinated in electrochemical...

  11. APPLICATIONS OF ELECTROCHEMICAL IMMUNOSENSORS TO ENVIRONMENTAL MONITORING

    EPA Science Inventory

    This paper discusses basic electrochemical immunoassay technology. Factors limiting the practical application of antibodies to anlaytical problems are also presented. It addresses the potential use of immunoassay methods based on electrochemical detection for the analysis of env...

  12. Multi-pass microscopy

    NASA Astrophysics Data System (ADS)

    Juffmann, Thomas; Klopfer, Brannon B.; Frankort, Timmo L. I.; Haslinger, Philipp; Kasevich, Mark A.

    2016-09-01

    Microscopy of biological specimens often requires low light levels to avoid damage. This yields images impaired by shot noise. An improved measurement accuracy at the Heisenberg limit can be achieved exploiting quantum correlations. If sample damage is the limiting resource, an equivalent limit can be reached by passing photons through a specimen multiple times sequentially. Here we use self-imaging cavities and employ a temporal post-selection scheme to present full-field multi-pass polarization and transmission micrographs with variance reductions of 4.4+/-0.8 dB (11.6+/-0.8 dB in a lossless setup) and 4.8+/-0.8 dB, respectively, compared with the single-pass shot-noise limit. If the accuracy is limited by the number of detected probe particles, our measurements show a variance reduction of 25.9+/-0.9 dB. The contrast enhancement capabilities in imaging and in diffraction studies are demonstrated with nanostructured samples and with embryonic kidney 293T cells. This approach to Heisenberg-limited microscopy does not rely on quantum state engineering.

  13. Multi-pass microscopy

    PubMed Central

    Juffmann, Thomas; Klopfer, Brannon B.; Frankort, Timmo L.I.; Haslinger, Philipp; Kasevich, Mark A.

    2016-01-01

    Microscopy of biological specimens often requires low light levels to avoid damage. This yields images impaired by shot noise. An improved measurement accuracy at the Heisenberg limit can be achieved exploiting quantum correlations. If sample damage is the limiting resource, an equivalent limit can be reached by passing photons through a specimen multiple times sequentially. Here we use self-imaging cavities and employ a temporal post-selection scheme to present full-field multi-pass polarization and transmission micrographs with variance reductions of 4.4±0.8 dB (11.6±0.8 dB in a lossless setup) and 4.8±0.8 dB, respectively, compared with the single-pass shot-noise limit. If the accuracy is limited by the number of detected probe particles, our measurements show a variance reduction of 25.9±0.9 dB. The contrast enhancement capabilities in imaging and in diffraction studies are demonstrated with nanostructured samples and with embryonic kidney 293T cells. This approach to Heisenberg-limited microscopy does not rely on quantum state engineering. PMID:27670525

  14. Magnetic force microscopy

    PubMed Central

    Passeri, Daniele; Dong, Chunhua; Reggente, Melania; Angeloni, Livia; Barteri, Mario; Scaramuzzo, Francesca A; De Angelis, Francesca; Marinelli, Fiorenzo; Antonelli, Flavia; Rinaldi, Federica; Marianecci, Carlotta; Carafa, Maria; Sorbo, Angela; Sordi, Daniela; Arends, Isabel WCE; Rossi, Marco

    2014-01-01

    Magnetic force microscopy (MFM) is an atomic force microscopy (AFM) based technique in which an AFM tip with a magnetic coating is used to probe local magnetic fields with the typical AFM spatial resolution, thus allowing one to acquire images reflecting the local magnetic properties of the samples at the nanoscale. Being a well established tool for the characterization of magnetic recording media, superconductors and magnetic nanomaterials, MFM is finding constantly increasing application in the study of magnetic properties of materials and systems of biological and biomedical interest. After reviewing these latter applications, three case studies are presented in which MFM is used to characterize: (i) magnetoferritin synthesized using apoferritin as molecular reactor; (ii) magnetic nanoparticles loaded niosomes to be used as nanocarriers for drug delivery; (iii) leukemic cells labeled using folic acid-coated core-shell superparamagnetic nanoparticles in order to exploit the presence of folate receptors on the cell membrane surface. In these examples, MFM data are quantitatively analyzed evidencing the limits of the simple analytical models currently used. Provided that suitable models are used to simulate the MFM response, MFM can be used to evaluate the magnetic momentum of the core of magnetoferritin, the iron entrapment efficiency in single vesicles, or the uptake of magnetic nanoparticles into cells. PMID:25050758

  15. Silver stain for electron microscopy

    NASA Technical Reports Server (NTRS)

    Corbett, R. L.

    1972-01-01

    Ammoniacal silver stain used for light microscopy was adapted advantageously for use with very thin biological sections required for electron microscopy. Silver stain can be performed in short time, has more contrast, and is especially useful for low power electron microscopy.

  16. Fundamental Studies Connected with Electrochemical Energy Storage

    NASA Technical Reports Server (NTRS)

    Buck, E.; Sen, R.

    1974-01-01

    Papers are presented which deal with electrochemical research activities. Emphasis is placed on electrochemical energy storage devices. Topics discussed include: adsorption of dendrite inhibitors on zinc; proton discharge process; electron and protron transfer; quantum mechanical formulation of electron transfer rates; and theory of electrochemical kinetics in terms of two models of activation; thermal and electrostatic.

  17. Image Force Microscopy

    NASA Astrophysics Data System (ADS)

    Rajapaksa, Indrajith

    In this thesis we describe an enhancement to the Atomic force microscope (AFM) to simultaneously gather topographic features and spectroscopic information .Compared to the current state of the art of near-field excitation and far-field detection AFM imaging techniques our system uses a radical new approach near-field excitation and near-field detection. By placing the detector in the near-field we achieve high signal to noise and single molecular resolution. The origin of our near-field detector signal is the image force gradient due to the interaction of the stimulated molecular dipole with its image on the metal probe. We designed and built an optical and electronic system to capture this signal and simultaneously image nano-scale surface topography and optical image force gradient. By varying the wavelength of the excitation beam we measure the induced optical image force gradient spectra of molecules on surface. These spectra show good agreement with the absorption spectra of the bulk molecules measured by conventional absorption spectroscopy. We show that image force gradient is directly proportional to the optical absorption dipole strength. Using Finite Element 3D electromagnetic simulations and using Lorentz model for the excited molecular dipole we showed that the image force gradient has a decay length of 1nm, making the theoretical resolution of this microscopy technique approximately 1 nm. This rapid decay was measured experimentally .This resolution was seen by the high contrasting spectroscopic images of molecules on the surface. In follow on experiments this technique was extended to provide surface Raman spectroscopy and microscopy at molecular resolution. We create an image force gradient interaction through optical parametric down conversion between stimulated Raman excited molecules on a surface and a cantilevered nanometer scale probe brought very close to it. Spectroscopy and microscopy on clusters of molecules have been performed. Single

  18. Applications of subsurface microscopy.

    PubMed

    Tetard, Laurene; Passian, Ali; Farahi, Rubye H; Voy, Brynn H; Thundat, Thomas

    2012-01-01

    Exploring the interior of a cell is of tremendous importance in order to assess the effects of nanomaterials on biological systems. Outside of a controlled laboratory environment, nanomaterials will most likely not be conveniently labeled or tagged so that their translocation within a biological system cannot be easily identified and quantified. Ideally, the characterization of nanomaterials within a cell requires a nondestructive, label-free, and subsurface approach. Subsurface nanoscale imaging represents a real challenge for instrumentation. Indeed the tools available for high resolution characterization, including optical, electron or scanning probe microscopies, mainly provide topography images or require taggants that fluoresce. Although the intercellular environment holds a great deal of information, subsurface visualization remains a poorly explored area. Recently, it was discovered that by mechanically perturbing a sample, it was possible to observe its response in time with nanoscale resolution by probing the surface with a micro-resonator such as a microcantilever probe. Microcantilevers are used as the force-sensing probes in atomic force microscopy (AFM), where the nanometer-scale probe tip on the microcantilever interacts with the sample in a highly controlled manner to produce high-resolution raster-scanned information of the sample surface. Taking advantage of the existing capabilities of AFM, we present a novel technique, mode synthesizing atomic force microscopy (MSAFM), which has the ability to probe subsurface structures such as non-labeled nanoparticles embedded in a cell. In MSAFM mechanical actuators (PZTs) excite the probe and the sample at different frequencies as depicted in the first figure of this chapter. The nonlinear nature of the tip-sample interaction, at the point of contact of the probe and the surface of the sample, in the contact mode AFM configuration permits the mixing of the elastic waves. The new dynamic system comprises new

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

    SciTech Connect

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

    2014-07-21

    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.

  20. Synthesis of Ru/multiwalled carbon nanotubes by microemulsion for electrochemical supercapacitor

    SciTech Connect

    Yan Shancheng; Qu Peng; Wang Haitao; Tian Tian; Xiao Zhongdang

    2008-10-02

    An efficient way to decorate multiwalled carbon nanotubes with Ru had been developed. In this method, Ru nanoparticles were prepared by water-in-oil reverse microemulsion, and the produced Ru anchored on MWCNTs. Transmission electron microscopy (TEM) result showed that RuO{sub 2} nanoparticles had the uniform size distribution after electrochemical oxidation. Energy dispersive X-rays (EDX) spectra elucidated the presence of ruthenium oxide in the as-prepared composites after electrochemical oxidation. Cyclic voltammetry result demonstrated that a specific capacitance of deposited ruthenium oxide electrode was significantly greater than that of the pristine MWCNTs electrode in the same medium.

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

    SciTech Connect

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

    2014-07-01

    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.

  2. Nanoscale electrochemical patterning reveals the active sites for catechol oxidation at graphite surfaces.

    PubMed

    Patel, Anisha N; McKelvey, Kim; Unwin, Patrick R

    2012-12-19

    Graphite-based electrodes (graphite, graphene, and nanotubes) are used widely in electrochemistry, and there is a long-standing view that graphite step edges are needed to catalyze many reactions, with the basal surface considered to be inert. In the present work, this model was tested directly for the first time using scanning electrochemical cell microscopy reactive patterning and shown to be incorrect. For the electro-oxidation of dopamine as a model process, the reaction rate was measured at high spatial resolution across a surface of highly oriented pyrolytic graphite. Oxidation products left behind in a pattern defined by the scanned electrochemical cell served as surface-site markers, allowing the electrochemical activity to be correlated directly with the graphite structure on the nanoscale. This process produced tens of thousands of electrochemical measurements at different locations across the basal surface, unambiguously revealing it to be highly electrochemically active, with step edges providing no enhanced activity. This new model of graphite electrodes has significant implications for the design of carbon-based biosensors, and the results are additionally important for understanding electrochemical processes on related sp(2)-hybridized materials such as pristine graphene and nanotubes.

  3. Hyperspectral light sheet microscopy

    NASA Astrophysics Data System (ADS)

    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.

  4. Sensitivity of photoacoustic microscopy

    PubMed Central

    Yao, Junjie; Wang, Lihong V.

    2014-01-01

    Building on its high spatial resolution, deep penetration depth and excellent image contrast, 3D photoacoustic microscopy (PAM) has grown tremendously since its first publication in 2005. Integrating optical excitation and acoustic detection, PAM has broken through both the optical diffusion and optical diffraction limits. PAM has 100% relative sensitivity to optical absorption (i.e., a given percentage change in the optical absorption coefficient yields the same percentage change in the photoacoustic amplitude), and its ultimate detection sensitivity is limited only by thermal noise. Focusing on the engineering aspects of PAM, this Review discusses the detection sensitivity of PAM, compares the detection efficiency of different PAM designs, and summarizes the imaging performance of various endogenous and exogenous contrast agents. It then describes representative PAM applications with high detection sensitivity, and outlines paths to further improvement. PMID:25302158

  5. Snapshot Hyperspectral Volumetric Microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Jiamin; Xiong, Bo; Lin, Xing; He, Jijun; Suo, Jinli; Dai, Qionghai

    2016-04-01

    The comprehensive analysis of biological specimens brings about the demand for capturing the spatial, temporal and spectral dimensions of visual information together. However, such high-dimensional video acquisition faces major challenges in developing large data throughput and effective multiplexing techniques. Here, we report the snapshot hyperspectral volumetric microscopy that computationally reconstructs hyperspectral profiles for high-resolution volumes of ~1000 μm × 1000 μm × 500 μm at video rate by a novel four-dimensional (4D) deconvolution algorithm. We validated the proposed approach with both numerical simulations for quantitative evaluation and various real experimental results on the prototype system. Different applications such as biological component analysis in bright field and spectral unmixing of multiple fluorescence are demonstrated. The experiments on moving fluorescent beads and GFP labelled drosophila larvae indicate the great potential of our method for observing multiple fluorescent markers in dynamic specimens.

  6. Snapshot Hyperspectral Volumetric Microscopy

    PubMed Central

    Wu, Jiamin; Xiong, Bo; Lin, Xing; He, Jijun; Suo, Jinli; Dai, Qionghai

    2016-01-01

    The comprehensive analysis of biological specimens brings about the demand for capturing the spatial, temporal and spectral dimensions of visual information together. However, such high-dimensional video acquisition faces major challenges in developing large data throughput and effective multiplexing techniques. Here, we report the snapshot hyperspectral volumetric microscopy that computationally reconstructs hyperspectral profiles for high-resolution volumes of ~1000 μm × 1000 μm × 500 μm at video rate by a novel four-dimensional (4D) deconvolution algorithm. We validated the proposed approach with both numerical simulations for quantitative evaluation and various real experimental results on the prototype system. Different applications such as biological component analysis in bright field and spectral unmixing of multiple fluorescence are demonstrated. The experiments on moving fluorescent beads and GFP labelled drosophila larvae indicate the great potential of our method for observing multiple fluorescent markers in dynamic specimens. PMID:27103155

  7. Characterization of Polymer Blends: Optical Microscopy (*Polarized, Interference and Phase Contrast Microscopy*) and Confocal Microscopy

    SciTech Connect

    Ramanathan, Nathan Muruganathan; Darling, Seth B.

    2015-01-01

    Chapter 15 surveys the characterization of macro, micro and meso morphologies of polymer blends by optical microscopy. Confocal Microscopy offers the ability to view the three dimensional morphology of polymer blends, popular in characterization of biological systems. Confocal microscopy uses point illumination and a spatial pinhole to eliminate out-of focus light in samples that are thicker than the focal plane.

  8. Extraterrestrial optical microscopy.

    PubMed

    Soffen, G A

    1969-07-01

    An examination of the literature concerned with the use of microscopy for planetary investigation reveals a serious deficiency of current efforts. Many scientists have recommended the use of a microscope for planetary investigation [Biology and the Exploration of Mars, C. S. Pittendrigh, W. Vishniac, and J. P. T. Pearman, Eds. (National Academy of Science-National Research Council, Washington, D. C., 1966), (a) D. Mazia, p. 31; (b) J. Lederberg, p. 137; (c) S. Fox, pp. 219, 226; (d) D. Glaser, p. 326; (e) D. Glaser, J. McCarthy, and M. Minsky, pp. 333, 341; (f) D. G. Rea, pp. 347-426; (g) P. G. Conger, pp. 409-414; (h) M. H. Fernandez, pp. 414-425; (i) D. Schwartz, pp.425-426 . H. P. Klein, Some Biological Problems in the Search for Extraterrestrial Life (American Astronautical Society, Washington, D. C., 1968).] but few are involved in developing the experiment. Since this is a particularly timely period for the preparation of planetary lander experiments, the reasons for this lack of effort would appear to be limited resources or an unclear course of action, rather than lack of interest. Microscopy used for planetary investigation is chiefly the interest of the biologist and the mineralogist. In both cases the desire to use magnifying optics in order to observe objects of submillimeter size is based upon the rich body of knowledge we have acquired from observing the terrestrial microcosm. In addition to purely imaging, certain special optical techniques, e.g., polarimetry, colorimetry, phase contrast, etc., can be used to enhance the interpretation of microscopic imaging data. This interaction of the optical with the chemical or structural aspects of nature can be used to great advantage in the exploration of extraterrestrial biology and mineralogy.

  9. Ultrasonic Force Microscopies

    NASA Astrophysics Data System (ADS)

    Kolosov, Oleg; Briggs, Andrew

    Ultrasonic Force Microscopy, or UFM, allows combination of two apparently mutually exclusive requirements for the nanomechanical probe—high stiffness for the efficient indentation and high mechanical compliance that brings force sensitivity. Somewhat inventively, UFM allows to combine these two virtues in the same cantilever by using indention of the sample at high frequency, when cantilever is very rigid, but detecting the result of this indention at much lower frequency. That is made possible due to the extreme nonlinearity of the nanoscale tip-surface junction force-distance dependence, that acts as "mechanical diode" detecting ultrasound in AFM. After introducing UFM principles, we discuss features of experimental UFM implementation, and the theory of contrast in this mode, progressing to quantitative measurements of contact stiffness. A variety of UFM applications ranging from semiconductor quantum nanostructures, graphene, very large scale integrated circuits, and reinforced ceramics to polymer composites and biological materials is presented via comprehensive imaging gallery accompanied by the guidance for the optimal UFM measurements of these materials. We also address effects of adhesion and topography on the elasticity imaging and the approaches for reducing artifacts connected with these effects. This is complemented by another extremely useful feature of UFM—ultrasound induced superlubricity that allows damage free imaging of materials ranging from stiff solid state devices and graphene to biological materials. Finally, we proceed to the exploration of time-resolved nanoscale phenomena using nonlinear mixing of multiple vibration frequencies in ultrasonic AFM—Heterodyne Force Microscopy, or HFM, that also include mixing of ultrasonic vibration with other periodic physical excitations, eg. electrical, photothermal, etc. Significant section of the chapter analyzes the ability of UFM and HFM to detect subsurface mechanical inhomogeneities, as well as

  10. A Renewable Electrochemical Magnetic Immunosensor Based on Gold Nanoparticle Labels

    SciTech Connect

    Liu, Guodong; Lin, Yuehe

    2005-05-24

    A particle-based renewable electrochemical magnetic immunosensor was developed by using magnetic beads and a gold nanoparticle label. Anti-IgG antibody-modified magnetic beads were attached to a renewable carbon paste transducer surface by magnets that were fixed inside the sensor. A gold nanoparticle label was capsulated to the surface of magnetic beads by sandwich immunoassay. Highly sensitive electrochemical stripping analysis offers a simple and fast method to quantify the capatured gold nanoparticle tracer and avoid the use of an enzyme label and substrate. The stripping signal of gold nanoparticle is related to the concentration of target IgG in the sample solution. A transmission electron microscopy image shows that the gold nanoparticles were successfully capsulated to the surface of magnetic beads through sandwich immunoreaction events. The parameters of immunoassay, including the loading of magnetic beads, the amount of gold nanoparticle conjugate, and the immunoreaction time, were optimized. The detection limit of 0.02 μg ml-1of IgG was obtained under optimum experimental conditions. Such particle-based electrochemical magnetic immunosensors could be readily used for simultaneous parallel detection of multiple proteins by using multiple inorganic metal nanoparticle tracers and are expected to open new opportunities for disease diagnostics and biosecurity.

  11. Materials analyses and electrochemical impedance of implantable metal electrodes.

    PubMed

    Howlader, Matiar M R; Ul Alam, Arif; Sharma, Rahul P; Deen, M Jamal

    2015-04-21

    Implantable electrodes with high flexibility, high mechanical fixation and low electrochemical impedance are desirable for neuromuscular activation because they provide safe, effective and stable stimulation. In this paper, we report on detailed materials and electrical analyses of three metal implantable electrodes - gold (Au), platinum (Pt) and titanium (Ti) - using X-ray photoelectron spectroscopy (XPS), scanning acoustic microscopy, drop shape analysis and electrochemical impedance spectroscopy. We investigated the cause of changes in electrochemical impedance of long-term immersed Au, Pt and Ti electrodes on liquid crystal polymers (LCPs) in phosphate buffered saline (PBS). We analyzed the surface wettability, surface and interface defects and the elemental depth profile of the electrode-adhesion layers on the LCP. The impedance of the electrodes decreased at lower frequencies, but increased at higher frequencies compared with that of the short-term immersion. The increase of impedances was influenced by the oxidation of the electrode/adhesion-layers that affected the double layer capacitance behavior of the electrode/PBS. The oxidation of the adhesion layer for all the electrodes was confirmed by XPS. Alkali ions (sodium) were adsorbed on the Au and Pt surfaces, but diffused into the Ti electrode and LCPs. The Pt electrode showed a higher sensitivity to surface and interface defects than that of Ti and Au electrodes. These findings may be useful when designing electrodes for long-term implantable devices.

  12. Electrochemical Thin Layers in Nanostructures for Energy Storage.

    PubMed

    Noked, Malachi; Liu, Chanyuan; Hu, Junkai; Gregorczyk, Keith; Rubloff, Gary W; Lee, Sang Bok

    2016-10-18

    Conventional electrical energy storage (EES) electrodes, such as rechargeable batteries, are mostly based on composites of monolithic micrometer sized particles bound together with polymeric and conductive carbon additives and binders. The kinetic limitations of these monolithic chunks of material are inherently linked to their electrical properties, the kinetics of ion insertion through their interface and ion migration in and through the composite phase. Redox chemistry of nanostructured materials in EES systems offer vast gains in power and energy. Furthermore, due to their thin nature, ion and electron transport is dramatically increased, especially when thin heterogeneous conducting layers are employed synergistically. However, since the stability of the electrode material is dictated by the nature of the electrochemical reaction and the accompanying volumetric and interfacial changes from the perspective of overall system lifetime, research with nanostructured materials has shown often indefinite conclusions: in some cases, an increase in unwanted side-reactions due to the high surface area (bad). In other cases, results have shown significantly better handling of mechanical stress that results from lithiation/delithiation (good). Despite these mixed results, scientifically informed design of thin electrode materials, with carefully chosen architectures, is considered a promising route to address many limitations witnessed in EES systems by reducing and protecting electrodes from parasitic reactions, accommodating mechanical stress due to volumetric changes from electrochemical reactions, and optimizing charge carrier mobilities from both the "ionic" and "electronic" points of view. Furthermore, precise nanoscale control over the electrode structure can enable accurate measurement through advanced spectroscopy and microscopy techniques. This Account summarizes recent findings related to thin electrode materials synthesized by atomic layer deposition (ALD) and

  13. Electrochemical Machining Removes Deep Obstructions

    NASA Technical Reports Server (NTRS)

    Catania, Mark J.

    1987-01-01

    Electrochemical machining (ECM) is effective way of removing obstructing material between two deep holes supposed to intersect but do not because of misalignment of drilling tools. ECM makes it possible to rework costly castings otherwise scrapped. Method fast even for tough or hard alloys and complicated three-dimensional shapes.

  14. [Electrochemical immunoanalysis of cardiac myoglobin].

    PubMed

    Shumiantseva, V V; Bulko, T V; Vagin, M Iu; Suprun, E V; Archakov, A I

    2010-01-01

    Method targeting the direct monitoring of myoglobin based on analysis of electrochemical parameters of modified electrodes were proposed. Method of direct detection is based on interaction of myoglobin with anti-myoglobin with subsequent electrochemical registration of hemeprotein. Myocardial infarction biomarker myoglobin was quantified at biological level using screen printed electrodes modified with gold nanoparticles stabilized with didodecyldimethylammonium bromide (DDAB) and antibodies. Proposed method did not require signal enhancement and amplification and also labeled secondary antibodies. Electro analysis has high specificity and sensitivity. Myoglobin -antibodies interaction was studied also with electrochemical impedance spectroscopy. Sensor has low detection limit and broad diapason of working concentrations (17.8 ng/ml-1780 ng/ml; 1 nM-10 nM). Method based on gold nanoparticles detection on the surface of electrodes was treated for myoglobin identification. AuNP worked as an electrochemical sensing platform: the oxidation of gold surface (resulted in gold oxide formation) upon polarization served as a basis for analytical response. The difference of cathodic peak area and peak high of gold oxide reduction in the case of electrodes with antibodies and electrodes with antibodies-myoglobin complex, was registered.

  15. Separator material for electrochemical cells

    DOEpatents

    Cieslak, Wendy R.; Storz, Leonard J.

    1991-01-01

    An electrochemical cell characterized as utilizing an aramid fiber as a separator material. The aramid fibers are especially suited for lithium/thionyl chloride battery systems. The battery separator made of aramid fibers possesses superior mechanical strength, chemical resistance, and is flame retardant.

  16. Recognized Leader in Electrochemical Purification

    ScienceCinema

    Hoppe, Eric

    2016-07-12

    PNNL scientists developed an electrochemical method for purifying copper, a key material that makes possible radiation detection systems of unprecedented sensitivity. The method begins with the purest copper materials available, and results in the lowest-background copper in the world. Chemist Eric Hoppe explains the process.

  17. Separator material for electrochemical cells

    DOEpatents

    Cieslak, W.R.; Storz, L.J.

    1991-03-26

    An electrochemical cell is characterized as utilizing an aramid fiber as a separator material. The aramid fibers are especially suited for lithium/thionyl chloride battery systems. The battery separator made of aramid fibers possesses superior mechanical strength, chemical resistance, and is flame retardant.

  18. Electrochemical cell with calcium anode

    DOEpatents

    Cooper, John F.; Hosmer, Pamela K.; Kelly, Benjamin E.

    1979-01-01

    An electrochemical cell comprising a calcium anode and a suitable cathode in an alkaline electrolyte consisting essentially of an aqueous solution of an hydroxide and a chloride. Specifically disclosed is a mechanically rechargeable calcium/air fuel cell with an aqueous NaOH/NaCl electrolyte.

  19. Thin Film Inorganic Electrochemical Systems.

    DTIC Science & Technology

    1995-07-01

    determined that thin film cathodes of LiCoO2 can be readily performed by either spray pyrolysis or spin coating . These cathodes are electrochemically...active. We have also determined that thin film anodes of Li4Ti5O12 can be prepared by spray pyrolysis or spin coating . These anodes are also

  20. Electrochemical processing of solid waste

    NASA Technical Reports Server (NTRS)

    Bockris, John OM.

    1987-01-01

    An investigation of electrochemical waste treatment methods suitable for closed, or partially closed, life support systems for manned space exploration is discussed. The technique being investigated involves the electrolysis of solid waste where the aim is to upgrade waste material (mainly fecal waste) to generate gases that can be recycled in a space station or planetary space environment.

  1. Recognized Leader in Electrochemical Purification

    SciTech Connect

    Hoppe, Eric

    2013-11-20

    PNNL scientists developed an electrochemical method for purifying copper, a key material that makes possible radiation detection systems of unprecedented sensitivity. The method begins with the purest copper materials available, and results in the lowest-background copper in the world. Chemist Eric Hoppe explains the process.

  2. Electrochemical Deposition Of Conductive Copolymers

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, Ganesan; Distefano, Salvador; Liang, Ranty H.

    1991-01-01

    Experiments show electrically conductive films are deposited on glassy carbon or indium tin oxide substrates by electrochemical polymerization of N-{(3-trimethoxy silyl) propyl} pyrrole or copolymerization with pyrrole. Copolymers of monomer I and pyrrole exhibit desired electrical conductivity as well as desired adhesion and other mechanical properties. When fully developed, new copolymerization process useful in making surface films of selectable conductivity.

  3. Sheet electrode for electrochemical systems

    DOEpatents

    Tsien, Hsue C.; Newby, Kenneth R.; Grimes, Patrick G.; Bellows, Richard J.

    1983-04-12

    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.

  4. Development of carbon electrodes for electrochemistry, solid-state electronics and multimodal atomic force microscopy imaging

    NASA Astrophysics Data System (ADS)

    Morton, Kirstin Claire

    Carbon is one of the most remarkable elements due to its wide abundance on Earth and its many allotropes, which include diamond and graphite. Many carbon allotropes are conductive and in recent decades scientists have discovered and synthesized many new forms of carbon, including graphene and carbon nanotubes. The work in this thesis specifically focuses on the fabrication and characterization of pyrolyzed parylene C (PPC), a conductive pyrocarbon, as an electrode material for diodes, as a conductive coating for atomic force microscopy (AFM) probes and as an ultramicroelectrode (UME) for the electrochemical interrogation of cellular systems in vitro. Herein, planar and three-dimensional (3D) PPC electrodes were microscopically, spectroscopically and electrochemically characterized. First, planar PPC films and PPC-coated nanopipettes were utilized to detect a model redox species, Ru(NH3) 6Cl3. Then, free-standing PPC thin films were chemically doped, with hydrazine and concentrated nitric acid, to yield p- and n-type carbon films. Doped PPC thin films were positioned in conjunction with doped silicon to create Schottky and p-n junction diodes for use in an alternating current half-wave rectifier circuit. Pyrolyzed parylene C has found particular merit as a 3D electrode coating of AFM probes. Current sensing-atomic force microscopy imaging in air of nanoscale metallic features was undertaken to demonstrate the electronic imaging applicability of PPC AFM probes. Upon further insulation with parylene C and modification with a focused ion beam, a PPC UME was microfabricated near the AFM probe apex and utilized for electrochemical imaging. Subsequently, scanning electrochemical microscopy-atomic force microscopy imaging was undertaken to electrochemically quantify and image the spatial location of dopamine exocytotic release, elicited mechanically via the AFM probe itself, from differentiated pheochromocytoma 12 cells in vitro.

  5. Virtual microscopy in pathology education.

    PubMed

    Dee, Fred R

    2009-08-01

    Technology for acquisition of virtual slides was developed in 1985; however, it was not until the late 1990s that desktop computers had enough processing speed to commercialize virtual microscopy and apply the technology to education. By 2000, the progressive decrease in use of traditional microscopy in medical student education had set the stage for the entry of virtual microscopy into medical schools. Since that time, it has been successfully implemented into many pathology courses in the United States and around the world, with surveys indicating that about 50% of pathology courses already have or expect to implement virtual microscopy. Over the last decade, in addition to an increasing ability to emulate traditional microscopy, virtual microscopy has allowed educators to take advantage of the accessibility, efficiency, and pedagogic versatility of the computer and the Internet. The cost of virtual microscopy in education is now quite reasonable after taking into account replacement cost for microscopes, maintenance of glass slides, and the fact that 1-dimensional microscope space can be converted to multiuse computer laboratories or research. Although the current technology for implementation of virtual microscopy in histopathology education is very good, it could be further improved upon by better low-power screen resolution and depth of field. Nevertheless, virtual microscopy is beginning to play an increasing role in continuing education, house staff education, and evaluation of competency in histopathology. As Z-axis viewing (focusing) becomes more efficient, virtual microscopy will also become integrated into education in cytology, hematology, microbiology, and urinalysis.

  6. Electrochemical binding and wiring in battery materials

    NASA Astrophysics Data System (ADS)

    Pejovnik, S.; Dominko, R.; Bele, M.; Gaberscek, M.; Jamnik, J.

    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 2O 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 2O 4 and LiCoO 2.

  7. Parallel Optical and Electrochemical DNA Detection

    NASA Astrophysics Data System (ADS)

    Knoll, Wolfgang; Liu, Jianyun; Niu, Lifang; Nielsen, Peter Eigil; Tiefenauer, Louis

    This contribution introduces strategies for the sensitive detection of oligonucleotides as bio-analytes binding from solution to a variety of probe architectures assembled at the (Au-) sensor surface. Detection principles based on surface plasmon optics and electrochemical techniques are compared. In particular, cyclic- and square wave voltammetry (SWV) are applied for the read-out of ferrocene redox labels conjugated to streptavidin that binds to the (biotinylated) DNA targets after hybridizing to the interfacial probe matrix of either DNA or peptide nucleic acid (PNA) strands. By employing streptavidin modified with fluorophores the identical sensor architecture can be used for the recording of hybridization reactions by surface plasmon fluorescence spectroscopy (SPFS). The Langmuir isotherms determined by both techniques, i.e., by SWV and SPFS, give virtually identical affinity constants KA, confirming that the mode of detection has no influence on the hybridization reaction. By using semiconducting nanoparticles as luminescence labels that can be tuned in their bandgap energies over a wide range of emission wavelengths surface plasmon fluorescence microscopy allows for the parallel read-out of multiple analyte binding events simultaneously.

  8. High damage tolerance of electrochemically lithiated silicon

    PubMed Central

    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

  9. Electrochemical chloride extraction: efficiency and side effects

    SciTech Connect

    Orellan, J.C.; Escadeillas, G.; Arliguie, G

    2004-02-01

    Some specimens of reinforced concrete cast with an alkali-resistant aggregate, previously maintained in a solution of NaCl, were subjected to an electrochemical chloride extraction (ECE). The chloride profiles before and after treatment were determined. Likewise, alkali ions profiles before and after treatment were determined. After treatment, some specimens were stored in a controlled atmosphere (60 deg. C and 100% RH) in order to accelerate the alkali-silica reaction, if any. Results of chloride content after treatment show that about 40% of the initial chloride is removed within 7 weeks. About one-half of the chloride close to steel was removed, but at the same time, significant amounts of alkali ions were observed around the steel. Microstructural observations by scanning electron microscopy (SEM) showed that after treatment, new cementitious phases containing higher concentrations of sodium, aluminum and potassium were formed. Moreover, alkali-silica gel was observed in the specimens stored at 60 deg. C and 100% RH. It may be possible that the ECE accumulates locally high amounts of alkali ions that stimulate the alkali-silica reaction even though the concrete contained nominally inert siliceous aggregates. The specimen expansions were not recorded, but no cracks were observed.

  10. High damage tolerance of electrochemically lithiated silicon

    DOE PAGES

    Wang, Xueju; Fan, Feifei; Wang, Jiangwei; ...

    2015-09-24

    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. In this paper, 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 ratiomore » 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. Finally, our results reveal the high damage tolerance in amorphous lithium-rich silicon alloys and have important implications for the development of durable rechargeable batteries.« less

  11. High damage tolerance of electrochemically lithiated silicon

    SciTech Connect

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

    2015-09-24

    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. In this paper, 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. Finally, our results reveal the high damage tolerance in amorphous lithium-rich silicon alloys and have important implications for the development of durable rechargeable batteries.

  12. High damage tolerance of electrochemically lithiated silicon.

    PubMed

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

    2015-09-24

    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.

  13. Synthesis and electrochemical properties of NiO nanospindles

    SciTech Connect

    Zhou, Hai; Lv, Baoliang; Xu, Yao; Wu, Dong

    2014-02-01

    Graphical abstract: NiO nanospindles with a different electrochemical activity as compared to those previous reports were synthesized via an agglomeration–dissolution–recrystallization growth process without the addition of any surfactant. - Highlights: • NiO nanospindles were synthesized without the addition of any surfactant. • The agglomeration–dissolution–recrystallization growth process was used to explain the precursors’ formation process of the spindle-like NiO. • As-obtained spindle-like NiO showed a different electrochemical activity as compared to those previous reports. - Abstract: NiO nanospindles were successfully synthesized via a hydrothermal and post-treatment method. The as-synthesized nanospindles were about several hundred nanometers in width and about one micrometer in length. X-ray diffraction (XRD) analysis revealed that the spindle-like structure was cubic NiO phase crystalline. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analysis indicated that these NiO nanospindles were of single crystal nature. On the basis of time-dependent experiments, a possible agglomeration–dissolution–recrystallization growth process was proposed to explain the formation process of the spindle-like precursors. The cyclic voltammetry (CV) measurement showed that the as-prepared spindle-like NiO exhibited a pseudo-capacitance behavior.

  14. Graphene-MnO 2 and graphene asymmetrical electrochemical capacitor with a high energy density in aqueous electrolyte

    NASA Astrophysics Data System (ADS)

    Deng, Lingjuan; Zhu, Gang; Wang, Jianfang; Kang, Liping; Liu, Zong-Huai; Yang, Zupei; Wang, Zenglin

    The graphene-manganese oxide hybrid material has been prepared by solution-phase assembly of aqueous dispersions of graphene nanosheets and manganese oxide nanosheets at room temperature. The morphology and structure of the obtained material are examined by scanning electron microscopy, transition electron microscopy, X-ray diffraction and N 2 adsorption-desorption. Electrochemical properties are characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. An asymmetric electrochemical capacitor with high energy and power densities based on the graphene-manganese oxide hybrid material as positive electrode and graphene as negative electrode in a neutral aqueous Na 2SO 4 solution as electrolyte is assembled. The asymmetrical electrochemical capacitor could cycle reversibly in a voltage of 0-1.7 V and give an energy density of 10.03 Wh kg -1 even at an average power density of 2.53 kW kg -1. Moreover, the asymmetrical electrochemical capacitor exhibit excellent cycle stability, and the capacitance retention of the asymmetrical electrochemical capacitor is 69% after repeating the galvanostatic charge-discharge test at the constant current density of 2230 mA g -1 for 10,000 cycles.

  15. Electrochemical synthesis of nanostructured materials for electrochemical energy conversion and storage.

    PubMed

    Li, Gao-Ren; Xu, Han; Lu, Xue-Feng; Feng, Jin-Xian; Tong, Ye-Xiang; Su, Cheng-Yong

    2013-05-21

    Electrochemical synthesis represents a highly efficient method for the fabrication of nanostructured energy materials, and various nanostructures, such as nanorods, nanowires, nanotubes, nanosheets, dendritic nanostructures, and composite nanostructures, can be easily fabricated with advantages of low cost, low synthetic temperature, high purity, simplicity, and environmental friendliness. The electrochemical synthesis, characterization, and application of electrochemical energy nanomaterials have advanced greatly in the past few decades, allowing an increasing understanding of nanostructure-property-performance relationships. Herein, we highlight some recent progress in the electrochemical synthesis of electrochemical energy materials with the assistance of additives and templates in solution or grafted onto metal or conductive polymer supports, with special attention to the effects on surface morphologies, structures and, more importantly, electrochemical performance. The methodology for preparing novel electrochemical energy nanomaterials and their potential applications has been summarized. Finally, we outline our personal perspectives on the electrochemical synthesis and applications of electrochemical energy nanomaterials.

  16. Electrochemical Glucose Biosensor of Platinum Nanospheres Connected by Carbon Nanotubes

    PubMed Central

    Claussen, Jonathan C.; Kim, Sungwon S.; Haque, Aeraj ul; Artiles, Mayra S.; Porterfield, D. Marshall; Fisher, Timothy S.

    2010-01-01

    Background Glucose biosensors comprised of nanomaterials such as carbon nanotubes (CNTs) and metallic nanoparticles offer enhanced electrochemical performance that produces highly sensitive glucose sensing. This article presents a facile biosensor fabrication and biofunctionalization procedure that utilizes CNTs electrochemically decorated with platinum (Pt) nanospheres to sense glucose amperometrically with high sensitivity. Method Carbon nanotubes are grown in situ by microwave plasma chemical vapor deposition (MPCVD) and electro-chemically decorated with Pt nanospheres to form a CNT/Pt nanosphere composite biosensor. Carbon nanotube electrodes are immobilized with fluorescently labeled bovine serum albumin (BSA) and analyzed with fluorescence microscopy to demonstrate their biocompatibility. The enzyme glucose oxidase (GOX) is immobilized onto the CNT/Pt nanosphere biosensor by a simple drop-coat method for amperometric glucose sensing. Results Fluorescence microscopy demonstrates the biofunctionalization capability of the sensor by portraying adsorption of fluorescently labeled BSA unto MPCVD-grown CNT electrodes. The subsequent GOX–CNT/Pt nanosphere biosensor demonstrates a high sensitivity toward H2O2 (7.4 μA/mM/cm2) and glucose (70 μA/mM/cm2), with a glucose detection limit and response time of 380 nM (signal-to-noise ratio = 3) and 8 s (t90%), respectively. The apparent Michaelis–Menten constant (0.64 mM) of the biosensor also reflects the improved sensitivity of the immobilized GOX/nanomaterial complexes. Conclusions The GOX–CNT/Pt nanosphere biosensor outperforms similar CNT, metallic nanoparticle, and more conventional carbon-based biosensors in terms of glucose sensitivity and detection limit. The biosensor fabrication and biofunctionalization scheme can easily be scaled and adapted for microsensors for physiological research applications that require highly sensitive glucose sensing. PMID:20307391

  17. Exploring Local Electrostatic Effects with Scanning Probe Microscopy: Implications for Piezoresponse Force Microscopy and Triboelectricity

    DOE PAGES

    Balke, Nina; Maksymovych, Petro; Jesse, Stephen; ...

    2014-09-25

    The implementation of contact mode Kelvin probe force microscopy (KPFM) utilizes the electrostatic interactions between tip and sample when the tip and sample are in contact with each other. Surprisingly, the electrostatic forces in contact are large enough to be measured even with tips as stiff as 4.5 N/m. As for traditional non-contact KPFM, the signal depends strongly on electrical properties of the sample, such as the dielectric constant, and the tip-properties, such as the stiffness. Since the tip is in contact with the sample, bias-induced changes in the junction potential between tip and sample can be measured with highermore » lateral and temporal resolution compared to traditional non-contact KPFM. Significant and reproducible variations of tip-surface capacitance are observed and attributed to surface electrochemical phenomena. Lastly, observations of significant surface charge states at zero bias and strong hysteretic electromechanical responses at non-ferroelectric surface have significant implications for fields such as triboelectricity and piezoresponse force microscopy.« less

  18. Exploring Local Electrostatic Effects with Scanning Probe Microscopy: Implications for Piezoresponse Force Microscopy and Triboelectricity

    SciTech Connect

    Balke, Nina; Maksymovych, Petro; Jesse, Stephen; Kravchenko, Ivan I.; Li, Qian; Kalinin, Sergei V.

    2014-09-25

    The implementation of contact mode Kelvin probe force microscopy (KPFM) utilizes the electrostatic interactions between tip and sample when the tip and sample are in contact with each other. Surprisingly, the electrostatic forces in contact are large enough to be measured even with tips as stiff as 4.5 N/m. As for traditional non-contact KPFM, the signal depends strongly on electrical properties of the sample, such as the dielectric constant, and the tip-properties, such as the stiffness. Since the tip is in contact with the sample, bias-induced changes in the junction potential between tip and sample can be measured with higher lateral and temporal resolution compared to traditional non-contact KPFM. Significant and reproducible variations of tip-surface capacitance are observed and attributed to surface electrochemical phenomena. Lastly, observations of significant surface charge states at zero bias and strong hysteretic electromechanical responses at non-ferroelectric surface have significant implications for fields such as triboelectricity and piezoresponse force microscopy.

  19. Intrinsic Friction Microscopy

    NASA Astrophysics Data System (ADS)

    Knorr, Daniel; Overney, Rene

    2008-03-01

    A novel scanning probe methodology based on lateral force microscopy is presented wherein kinetic friction measurements, obtained as a function of velocity for various temperatures, are used to deduce apparent Arrhenius-type activation energies for surface and subsurface molecular mobilities. Depending on the coupling strength (cooperativity) between molecular mobilities involved the dissipation energy can carry a significant entropic energy contribution, accounting for the majority of the apparent Arrhenius activation energy. The intrinsic friction methodology also provides a means of directly separating enthalpic energy contributions from entropic ones by employing absolute rate theory. As such, the degree of cooperativity in the system is readily apparent. This methodology is illustrated with nanoscale tribological experiments on two systems, (1) monodisperse, atactic polystyrene and (2) self assembling molecular glassy chromophores. In polystyrene, dissipation was found to be a discrete function of loading, where the γ-relaxation (phenyl group rotation) was recovered for ultra low loads and the β-relaxation (local backbone translation) for higher loads in the same temperature range, indicating sensitivity to surface and subsurface mobilities. For self assembling glassy chromophores, the degree of intermolecular cooperativity was deduced using the methodology, resulting in an increased understanding of the interactions between self assembling molecules.

  20. Ultrafast scanning probe microscopy

    DOEpatents

    Weiss, Shimon; Chemla, Daniel S.; Ogletree, D. Frank; Botkin, David

    1995-01-01

    An ultrafast scanning probe microscopy method for achieving subpicosecond-temporal resolution and submicron-spatial resolution of an observation sample. In one embodiment of the present claimed invention, a single short optical pulse is generated and is split into first and second pulses. One of the pulses is delayed using variable time delay means. The first pulse is then directed at an observation sample located proximate to the probe of a scanning probe microscope. The scanning probe microscope produces probe-sample signals indicative of the response of the probe to characteristics of the sample. The second pulse is used to modulate the probe of the scanning probe microscope. The time delay between the first and second pulses is then varied. The probe-sample response signal is recorded at each of the various time delays created between the first and second pulses. The probe-sample response signal is then plotted as a function of time delay to produce a cross-correlation of the probe sample response. In so doing, the present invention provides simultaneous subpicosecond-temporal resolution and submicron-spatial resolution of the sample.

  1. Ultrafast scanning tunneling microscopy

    SciTech Connect

    Botkin, D.A. |

    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.

  2. NMR imaging microscopy

    SciTech Connect

    Not Available

    1986-10-01

    In the past several years, proton nuclear magnetic resonance (NMR) imaging has become an established technique in diagnostic medicine and biomedical research. Although much of the work in this field has been directed toward development of whole-body imagers, James Aguayo, Stephen Blackband, and Joseph Schoeninger of the Johns Hopkins University School of Medicine working with Markus Hintermann and Mark Mattingly of Bruker Medical Instruments, recently developed a small-bore NMR microscope with sufficient resolution to image a single African clawed toad cell (Nature 1986, 322, 190-91). This improved resolution should lead to increased use of NMR imaging for chemical, as well as biological or physiological, applications. The future of NMR microscopy, like that of many other newly emerging techniques, is ripe with possibilities. Because of its high cost, however, it is likely to remain primarily a research tool for some time. ''It's like having a camera,'' says Smith. ''You've got a way to look at things at very fine levels, and people are going to find lots of uses for it. But it is a very expensive technique - it costs $100,000 to add imaging capability once you have a high-resolution NMR, which itself is at least a $300,000 instrument. If it can answer even a few questions that can't be answered any other way, though, it may be well worth the cost.''

  3. Mueller polarimetric microscopy

    NASA Astrophysics Data System (ADS)

    Laude-Boulesteix, Blandine; De Martino, Antonello; Le Naour, Gilles; Genestie, Catherine; Schwartz, Laurent; Garcia-Caurel, Enric; Drevillon, Bernard

    2004-07-01

    We present a multispectral polarimetric imaging system well suited for complete Mueller matrix microscopy. The source is a spectrally filtered halogen light bulb, and the image is formed on a fast CCD camera The light polarization is modulated before the sample and analyzed after the sample by using nematic liquid crystal modulators.. The whole Mueller matrix image of the sample is typically measured over 5 seconds for a good signal-to-noise ratio. The instrument design, together with an original and easy-to-operate calibration procedure provides a high polarimetric accuracy over wide ranges of wavelengths and magnifications. Mueller polarimetry provides separate images of scalar and vector retardation and dichroism of the sample, together with its depolarizing power, while all these effects do contribute simultaneously to the contrasts observed in standard polarized microsopy. Polarimetric images of several samples, namely an unstained rabbit cornea, a picrosirius red stained hepatic biopsy, and a rat artery specifically stained for collagen III are shown and discussed

  4. In vivo microscopy.

    PubMed

    Peti-Peterdi, János

    2016-04-01

    This article summarizes the past, present, and future promise of multiphoton excitation fluorescence microscopy for intravital kidney imaging. During the past 15years, several high-power visual research approaches have been developed using multiphoton imaging to study the normal functions of the healthy, intact, living kidney, and the various molecular and cellular mechanisms of the development of kidney diseases. In this review, the main focus will be on intravital multiphoton imaging of the glomerulus, the structure and function of the glomerular filtration barrier, especially the podocyte. Examples will be given for the combination of two powerful research tools, in vivo multiphoton imaging and mouse genetics using commercially available whole animal models for the detailed characterization of glomerular cell types, their function and fate, and for the better understanding of the molecular mechanisms of glomerular pathologies. One of the new modalities of multiphoton imaging, serial imaging of the same glomerulus in the same animal over several days will be emphasized for its potential for further advancing the field of nephrology research.

  5. Microscopy of semiconducting materials

    NASA Astrophysics Data System (ADS)

    Pennycook, S. J.

    1991-04-01

    The purpose of the trip was to present an invited talk at the 7th Oxford Conference on Microscopy of Semiconducting Materials entitled, High-Resolution Z-Contrast Imaging of Heterostructures and Superlattices, (Oxford, United Kingdom) and to visit VG Microscopes, East Grinstead, for discussions on the progress of the Oak Ridge National Laboratory (ORNL) 300-kV high-resolution scanning transmission electron microscope (STEM), which is currently on order. The traveler also visited three other institutions with 100-kV STEMs that either have or intend to purchase the necessary modifications to provide Z-contrast capability similar to that of the existing ORNL machine. Specifically, Max-Planck Institut fuer Metallforschung (Stuttgart, Germany); Cambridge University, Department of Materials Science and Metallurgy (Cambridge, United Kingdom); and Cavendish Laboratory, Cambridge University (Cambridge, United Kingdom) were visited. In addition, discussions were held with C. Humphreys on the possibility of obtaining joint funding for collaborative research involving electron beam writing and Z-contrast imaging in the Cambridge and Oak Ridge STEMs, respectively.

  6. Ultrafast scanning probe microscopy

    DOEpatents

    Weiss, S.; Chemla, D.S.; Ogletree, D.F.; Botkin, D.

    1995-05-16

    An ultrafast scanning probe microscopy method is described for achieving subpicosecond-temporal resolution and submicron-spatial resolution of an observation sample. In one embodiment of the present claimed invention, a single short optical pulse is generated and is split into first and second pulses. One of the pulses is delayed using variable time delay means. The first pulse is then directed at an observation sample located proximate to the probe of a scanning probe microscope. The scanning probe microscope produces probe-sample signals indicative of the response of the probe to characteristics of the sample. The second pulse is used to modulate the probe of the scanning probe microscope. The time delay between the first and second pulses is then varied. The probe-sample response signal is recorded at each of the various time delays created between the first and second pulses. The probe-sample response signal is then plotted as a function of time delay to produce a cross-correlation of the probe sample response. In so doing, the present invention provides simultaneous subpicosecond-temporal resolution and submicron-spatial resolution of the sample. 6 Figs.

  7. Enhanced Electrochemical Catalytic Efficiencies of Electrochemically Deposited Platinum Nanocubes as a Counter Electrode for Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Wei, Yu-Hsuan; Tsai, Ming-Chi; Ma, Chen-Chi M.; Wu, Hsuan-Chung; Tseng, Fan-Gang; Tsai, Chuen-Horng; Hsieh, Chien-Kuo

    2015-12-01

    Platinum nanocubes (PtNCs) were deposited onto a fluorine-doped tin oxide glass by electrochemical deposition (ECD) method and utilized as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). In this study, we controlled the growth of the crystalline plane to synthesize the single-crystal PtNCs at room temperature. The morphologies and crystalline nanostructure of the ECD PtNCs were examined by field emission scanning electron microscopy and high-resolution transmission electron microscopy. The surface roughness of the ECD PtNCs was examined by atomic force microscopy. The electrochemical properties of the ECD PtNCs were analyzed by cyclic voltammetry, Tafel polarization, and electrochemical impedance spectra. The Pt loading was examined by inductively coupled plasma mass spectrometry. The DSSCs were assembled via an N719 dye-sensitized titanium dioxide working electrode, an iodine-based electrolyte, and a CE. The photoelectric conversion efficiency (PCE) of the DSSCs with the ECD PtNC CE was examined under the illumination of AM 1.5 (100 mWcm-2). The PtNCs in this study presented a single-crystal nanostructure that can raise the electron mobility to let up the charge-transfer impedance and promote the charge-transfer rate. In this work, the electrocatalytic mass activity (MA) of the Pt film and PtNCs was 1.508 and 4.088 mAmg-1, respectively, and the MA of PtNCs was 2.71 times than that of the Pt film. The DSSCs with the pulse-ECD PtNC CE showed a PCE of 6.48 %, which is higher than the cell using the conventional Pt film CE (a PCE of 6.18 %). In contrast to the conventional Pt film CE which is fabricated by electron beam evaporation method, our pulse-ECD PtNCs maximized the Pt catalytic properties as a CE in DSSCs. The results demonstrated that the PtNCs played a good catalyst for iodide/triiodide redox couple reactions in the DSSCs and provided a potential strategy for electrochemical catalytic applications.

  8. Sample preparation for STED microscopy.

    PubMed

    Wurm, Christian A; Neumann, Daniel; Schmidt, Roman; Egner, Alexander; Jakobs, Stefan

    2010-01-01

    Since the discovery of the diffraction barrier in the late nineteenth century, it has been commonly accepted that with far-field optical microscopy it is not possible to resolve structural details considerably finer than half the wavelength of light. The emergence of STED microscopy showed that, at least for fluorescence imaging, these limits can be overcome. Since STED microscopy is a far-field technique, in principle, the same sample preparation as for conventional confocal microscopy may be utilized. The increased resolution, however, requires additional precautions to ensure the structural preservation of the specimen. We present robust protocols to generate test samples for STED microscopy. These protocols for bead samples and immunolabeled mammalian cells may be used as starting points to adapt existing labeling strategies for the requirements of sub-diffraction resolution microscopy.

  9. Corrosion monitoring system based on measurement and analysis of electrochemical noise

    SciTech Connect

    Legat, A.; Dolecek, V.

    1995-04-01

    A corrosion monitoring system using electrochemical noise measurements and their numerical analysis was developed. Electrochemical noise was measured in a freely corroding system containing three identical metal electrodes. A voltage signal generated by the first pair of electrodes and a current signal generated by the second pair were measured, and the data were fed into a computer. A mathematical model that included signal processing and pattern recognition was implemented using computer software. Analysis of the electrochemical noise enabled determination of the corrosion rate and the corrosion type. The reliability of the corrosion monitoring system was tested against various reference methods (visual inspection, scanning electron microscopy, current-vs-potential curves, and electrical resistance). Tests were performed on steel and aluminum in aqueous solutions of various pH and conductivity values.

  10. Electrochemical characteristics and impedance spectroscopy studies of nano-cobalt silicate hydroxide for supercapacitor

    NASA Astrophysics Data System (ADS)

    Zhang, Guo-Qing; Zhao, Yong-Qing; Tao, Feng; Li, Hu-Lin

    Cobalt silicate hydroxide (Co 3[Si 2O 5] 2[OH] 2) was prepared by chemical method for use in electrochemical capacitors. X-ray diffraction (XRD) and transmission electron microscopy (TEM) tests indicate that the material was pure hexagonal phase with uniform nanometer size distribution. Cyclic voltammeter (CV) and galvanostatic charge/discharge measurements show that the cobalt silicate hydroxide-based electrode has stable electrochemical capacitor properties between potential range of 0.1-0.55 V with a maximum specific capacitance of 237 F g -1 in alkaline solution and 95% of capacity efficiency was reached after 150 cycles. Electrochemical impedance spectra (EIS) investigation illustrates that the capacitance of the test electrode was mainly consisted of pseudo-capacitance, which was caused by underpotential deposition of H 3O + at the electrode surface.

  11. Electrochemically deposited gold nanoparticles on a carbon paste electrode surface for the determination of mercury.

    PubMed

    Sahoo, Srikant; Satpati, Ashis Kumar; Reddy, Annareddy Venkata Ramana

    2015-01-01

    An electrochemical method was developed for the determination of Hg at ultratrace levels using an Au nanoparticle (AuNP) array modified carbon paste electrode (CPE) by anodic stripping voltammetry. Scanning electron microscopy measurements imaged the size and shape of AuNPs on the CPE substrate; it was possible to tune the size and the NP density by changing the deposition time and medium. Electrochemical characterization of the AuNP modified CPE was carried out using cyclic voltammetry and electrochemical impedance measurements. Interferences due to some commonly occurring metal ions and surfactants on the stripping peak of Hg were also investigated. The 3σ detection limit for Hg using the AuNP modified electrode was as 0.24 μg/L. This method was applied to determine Hg in soil samples.

  12. Electrochemical assisted photocatalytic degradation of salicylic acid with highly ordered TiO2 nanotube electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Zhu, Jinwei; Wang, Ying; Feng, Jiangtao; Yan, Wei; Xu, Hao

    2014-07-01

    To explore the kinetics of photoelectrocatalytic degradation of salicylic acid, one of the important PPCPs, highly ordered TiO2 nanotube arrays (NTs) were prepared by the electrochemical anodization and characterized with scanning electron microscopy and X-ray diffraction techniques. The effect of TiO2 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.

  13. Study on synthesis and electrochemical properties of hematite nanotubes for energy storage in supercapacitor

    SciTech Connect

    Nathan, D. Muthu Gnana Theresa; Sagayaraj, P.

    2015-06-24

    Hematite nanotubes (α-Fe{sub 2}O{sub 3} NTs) are synthesized via a cost-effective and environmental-friendly hydrothermal technique. Field emission scanning electron microscopy and X-ray powder diffraction analyses reveal the formation of α-Fe{sub 2}O{sub 3} NTs with high crystallinity and purity. Optical behavior of α-Fe{sub 2}O{sub 3} NTs is studied employing UV-visible spectroscopy. Electrochemical properties of the as-prepared electrode material are investigated by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy in a three electrode cell. The synthesized α-Fe{sub 2}O{sub 3} NTs present enhanced pseudocapacitive performance with high specific capacity of 230 Fg{sup −1} at current density of 1 Ag{sup −1}. The prepared α-Fe{sub 2}O{sub 3} NTs can be utilized as a potential electrode material for electrochemical capacitor applications.

  14. Electrochemical Polishing Applications and EIS of a Novel Choline Chloride-Based Ionic Liquid

    SciTech Connect

    Wixtrom, Alex I.; Buhler, Jessica E.; Reece, Charles E.; Abdel-Fattah, Tarek M.

    2013-06-01

    Minimal surface roughness is a critical feature for high-field superconducting radio frequency (SRF) cavities used to engineer particle accelerators. Current methods for polishing Niobium cavities typically utilize solutions containing a mixture of concentrated sulfuric and hydrofluoric acid. Polishing processes such as these are effective, yet there are many hazards and costs associated with the use (and safe disposal) of the concentrated acid solutions. An alternative method for electrochemical polishing of the cavities was explored using a novel ionic liquid solution containing choline chloride. Potentiostatic electrochemical impedance spectroscopy (EIS) was used to analyze the ionic polishing solution. Final surface roughness of the Nb was found to be comparable to that of the acid-polishing method, as assessed by atomic force microscopy (AFM). This indicates that ionic liquid-based electrochemical polishing of Nb is a viable replacement for acid-based methods for preparation of SRF cavities.

  15. Chitosan/graphene oxide nanocomposite films with enhanced interfacial interaction and their electrochemical applications

    NASA Astrophysics Data System (ADS)

    He, Linghao; Wang, Hongfang; Xia, Guangmei; Sun, Jing; Song, Rui

    2014-09-01

    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.

  16. Study on synthesis and electrochemical properties of hematite nanotubes for energy storage in supercapacitor

    NASA Astrophysics Data System (ADS)

    Nathan, D. Muthu Gnana Theresa; Sagayaraj, P.

    2015-06-01

    Hematite nanotubes (α-Fe2O3 NTs) are synthesized via a cost-effective and environmental-friendly hydrothermal technique. Field emission scanning electron microscopy and X-ray powder diffraction analyses reveal the formation of α-Fe2O3 NTs with high crystallinity and purity. Optical behavior of α-Fe2O3 NTs is studied employing UV-visible spectroscopy. Electrochemical properties of the as-prepared electrode material are investigated by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy in a three electrode cell. The synthesized α-Fe2O3 NTs present enhanced pseudocapacitive performance with high specific capacity of 230 Fg-1 at current density of 1 Ag-1. The prepared α-Fe2O3 NTs can be utilized as a potential electrode material for electrochemical capacitor applications.

  17. In situ characterization of localized corrosion of stainless steel by scanning electrochemical microscope

    NASA Astrophysics Data System (ADS)

    Yin, Yuehua; Niu, Lin; Lu, Min; Guo, Weikuan; Chen, Shenhao

    2009-08-01

    Scanning electrochemical microscopy (SECM) area scan measurements have been performed to investigate the localized corrosion of type 304 stainless steel in neutral chloride solution. Variations in the Faradaic current measured at selected tip potential values can be related to changes in the local concentration and electrochemical activities of electroactive species involved in corrosion reactions occurring at the substrate as a function of immersion times of the substrate and polarized currents or potentials applied on the substrate. To further verify the results acquired from cyclic voltammetric experiments, SECM measurements were employed to in situ study the compositions and electrochemical activity distribution profile of the pitting corrosion products of stainless steel. It has been demonstrated that the combination of feedback current mode with generation-collection (G-C) mode of SECM is suitable to elucidate the possible reaction mechanisms and paths involved in the localize corrosion of stainless steel in neutral chloride solution.

  18. Structure and opto-electrochemical properties of ZnO nanowires grown on n-Si substrate.

    PubMed

    Ladanov, Mikhail; Ram, Manoj K; Matthews, Garrett; Kumar, Ashok

    2011-07-19

    Zinc oxide (ZnO) nanostructures have attracted great attention as a promising functional material with unique properties suitable for applications in UV lasers, light emitting diodes, field emission devices, sensors, field effect transistors, and solar cells. In the present work, ZnO nanowires have been synthesized on an n-type Si substrate using a hydrothermal method where surfactant acted as a modifying and protecting agent. The surface morphology, electrochemical properties, and opto-electrochemical properties of ZnO nanowires are investigated by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), cyclic voltammetry, and impedance spectroscopy techniques. The cycling characteristics and rate capability of the ZnO nanowires are explored through electrochemical studies performed under varying electrolytes. The photo response is observed using UV radiation. It is demonstrated that crystallinity, particle size, and morphology all play significant roles in the electrochemical performance of the ZnO electrodes.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Flower-like NiO structures: Controlled hydrothermal synthesis and electrochemical characteristic

    SciTech Connect

    Chai, Hui; Chen, Xuan; Jia, Dianzeng; Bao, Shujuan; Zhou, Wanyong

    2012-12-15

    Graphical abstract: Flower-like porous NiO was obtained via thermal decomposition of the precursor prepared by a hydrothermal process using hexamethylenetetramine and polyethylene glycol as hydrolysis-controlling agent and surfactant, respectively. The morphology and microstructure of as-synthesized NiO were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results of electrochemical measurements demonstrated that the flower-like porous NiO has high capacity (340 F g{sup −1}) with excellent cycling performance as electrode materials of electrochemical capacitors (ECs), which may be attributed to the unique microstrcture of NiO. Data analyses indicated that NiO with novel porous structure attractive for practical and large-scale applications in electrochemical capacitors. Display Omitted Highlights: ► Synthesis and characterization of NiO with novel porous structure is presented in this work. ► The electrochemical performance of product was examined. ► NiO with excellent performance as electrode materials may be due to the unique microstrcture. ► NiO with novel porous structure attractive for practical with high capacity (340 F g{sup −1}). -- Abstract: Flower-like porous NiO was obtained by thermal decomposition of the precursor prepared by a hydrothermal process with hexamethylenetetramine and polyethylene glycol as hydrolysis-controlling agent and surfactant, respectively. The morphology and microstructure of as-synthesized NiO were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The resulting structures of NiO exhibited porous like petal building blocks. The electrochemical measurements’ results demonstrated that flower-like porous NiO has high capacity (340 F g{sup −1}) with excellent cycling performance as electrode materials for

  1. Graphene as a spacer to layer-by-layer assemble electrochemically functionalized nanostructures for molecular bioelectronic devices.

    PubMed

    Wang, Xiang; Wang, Jingfang; Cheng, Hanjun; Yu, Ping; Ye, Jianshan; Mao, Lanqun

    2011-09-06

    This study demonstrates the capability of graphene as a spacer to form electrochemically functionalized multilayered nanostructures onto electrodes in a controllable manner through layer-by-layer (LBL) chemistry. Methylene green (MG) and positively charged methylimidazolium-functionalized multiwalled carbon nanotubes (MWNTs) were used as examples of electroactive species and electrochemically useful components for the assembly, respectively. By using graphene as the spacer, the multilayered nanostructures of graphene/MG and graphene/MWNT could be readily formed onto electrodes with the LBL method on the basis of the electrostatic and/or π-π interaction(s) between graphene and the electrochemically useful components. Scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV-vis), and cyclic voltammetry (CV) were used to characterize the assembly processes, and the results revealed that nanostructure assembly was uniform and effective with graphene as the spacer. Electrochemical studies demonstrate that the assembled nanostructures possess excellent electrochemical properties and electrocatalytic activity toward the oxidation of NADH and could thus be used as electronic transducers for bioelectronic devices. This potential was further demonstrated by using an alcohol dehydrogenase-based electrochemical biosensor and glucose dehydrogenase-based glucose/O(2) biofuel cell as typical examples. This study offers a simple route to the controllable formation of graphene-based electrochemically functionalized nanostructures that can be used for the development of molecular bioelectronic devices such as biosensors and biofuel cells.

  2. Zeolitic imidazolate framework-based electrochemical biosensor for in vivo electrochemical measurements.

    PubMed

    Ma, Wenjie; Jiang, Qin; Yu, Ping; Yang, Lifen; Mao, Lanqun

    2013-08-06

    This study demonstrates the first exploitation of zeolitic imidazolate frameworks (ZIFs) as the matrix for constructing integrated dehydrogenase-based electrochemical biosensors for in vivo measurement of neurochemicals, such as glucose. In this study, we find that ZIFs are able to serve as a matrix for coimmobilizing electrocatalysts (i.e., methylene green, MG) and dehydrogenases (i.e., glucose dehydrogenase, GDH) onto the electrode surface and an integrated electrochemical biosensor is readily formed. We synthesize a series of ZIFs, including ZIF-7, ZIF-8, ZIF-67, ZIF-68, and ZIF-70 with different pore sizes, surface areas, and functional groups. The adsorption capabilities toward MG and GDH of these ZIFs are systematically studied with UV-vis spectroscopy, confocal laser scanning microscopy, and Fourier transfer-infrared spectroscopy. Among all the ZIFs demonstrated here, ZIF-70 shows excellent adsorption capacities toward both MG and GDH and is thus employed as the matrix for our glucose biosensor. To construct the biosensor, we first drop-coat a MG/ZIF-70 composite onto a glassy carbon electrode and then coat GDH onto the MG/ZIF-70 composite. In a continuous-flow system, the as-prepared ZIF-based biosensor is very sensitive to glucose with a linear range of 0.1-2 mM. Moreover, the ZIF-based biosensor is more highly selective on glucose than on other endogenous electroactive species in the cerebral system. In the end, we demonstrate that our biosensor is capable of monitoring dialysate glucose collected from the brain of guinea pigs selectively and in a near real-time pattern.

  3. Surface working of 304L stainless steel: Impact on microstructure, electrochemical behavior and SCC resistance

    SciTech Connect

    Acharyya, S.G.; Khandelwal, A.; Kain, V.; Kumar, A.; Samajdar, I.

    2012-10-15

    The effect of surface working operations on the microstructure, electrochemical behavior and stress corrosion cracking resistance of 304L stainless steel (SS) was investigated in this study. The material was subjected to (a) solution annealing (b) machining and (c) grinding operations. Microstructural characterization was done using stereo microscopy and electron back scattered diffraction (EBSD) technique. The electrochemical nature of the surfaces in machined, ground and solution annealed condition were studied using potentiodynamic polarization and scanning electrochemical microscopy (SECM) in borate buffer solution. The stress corrosion cracking resistance of 304L SS in different conditions was studied by exposing the samples to boiling MgCl{sub 2} environment. Results revealed that the heavy plastic deformation and residual stresses present near the surface due to machining and grinding operations make 304L SS electrochemically more active and susceptible to stress corrosion cracking. Ground sample showed highest magnitude of current density in the passive potential range followed by machined and solution annealed 304L SS. Micro-electrochemical studies established that surface working promotes localized corrosion along the surface asperities which could lead to crack initiation. - Highlights: Black-Right-Pointing-Pointer Machining/grinding produce extensive grain fragmentation near the surface of 304L SS. Black-Right-Pointing-Pointer Machining/grinding result in martensitic transformation near the surface of 304L SS. Black-Right-Pointing-Pointer Machining/grinding drastically reduce the SCC resistance of 304L SS in chloride. Black-Right-Pointing-Pointer Machining/grinding make the surface of 304L SS electrochemically much more active. Black-Right-Pointing-Pointer SECM study reveal that preferential dissolution takes place along surface asperities.

  4. Electrochemical promotion of catalytic reactions

    NASA Astrophysics Data System (ADS)

    Imbihl, R.

    2010-05-01

    The electrochemical promotion of heterogeneously catalyzed reactions (EPOC) became feasible through the use of porous metal electrodes interfaced to a solid electrolyte. With the O 2- conducting yttrium stabilized zirconia (YSZ), the Na + conducting β″-Al 2O 3 (β-alumina), and several other types of solid electrolytes the EPOC effect has been demonstrated for about 100 reaction systems in studies conducted mainly in the mbar range. Surface science investigations showed that the physical basis for the EPOC effect lies in the electrochemically induced spillover of oxygen and alkali metal, respectively, onto the surface of the metal electrodes. For the catalytic promotion effect general concepts and mechanistic schemes were proposed but these concepts and schemes are largely speculative. Applying surface analytical tools to EPOC systems the proposed mechanistic schemes can be verified or invalidated. This report summarizes the progress which has been achieved in the mechanistic understanding of the EPOC effect.

  5. Electrochemical corrosion of metallic biomaterials.

    PubMed

    Pourbaix, M

    1984-05-01

    Methods of electrochemical thermodynamics (electrode potential-pH equilibrium diagrams) and electrochemical kinetics (polarization curves) may help to understand and predict the corrosion behaviour of metals and alloys in the presence of body fluids. A short review of the literature is given concerning some applications of such methods, both in vitro and in vivo, relating to surgical implants (stainless steels, chromium-cobalt-molybdenum alloys, titanium and titanium alloys) and to dental alloys (silver-tin-copper amalgams, silver-base and gold-base casting alloys, nickel-base casting alloys). Attention is drawn to the necessity of more basic research on crevice- and fretting-corrosion of surgical implant materials and dental alloys, and to the toxicity of corrosion products. A perfect understanding of the exact significance of electrode-potentials is essential for the success of such a task.

  6. Electrochemical oxidation of chemical weapons

    SciTech Connect

    Surma, J.E.

    1994-05-01

    Catalyzed electrochemical oxidation (CEO), a low-temperature electrochemical oxidation technique, is being examined for its potential use in destroying chemical warfare agents. The CEO process oxidizes organic compounds to form carbon dioxide and water. A bench-scale CEO system was used in three separate tests sponsored by the US Department of Energy`s (DOE) Office of Intelligence and National Security through the Advanced Concepts Program. The tests examined the effectiveness of CEO in destroying sarin (GB), a chemical nerve agent. The tests used 0.5 mL, 0.95 mL, and 1.0 mL of GB, corresponding to 544 mg, 816 mg, and 1,090 mg, respectively, of GB. Analysis of the off gas showed that, under continuous processing of the GB agent, destruction efficiencies of better than six 9s (99.9999% destroyed) could be achieved.

  7. Electrochemical treatment of liquid wastes

    SciTech Connect

    Hobbs, D.

    1996-10-01

    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.

  8. Electrochemically driven mechanical energy harvesting

    PubMed Central

    Kim, Sangtae; Choi, Soon Ju; Zhao, Kejie; Yang, Hui; Gobbi, Giorgia; Zhang, Sulin; Li, Ju

    2016-01-01

    Efficient mechanical energy harvesters enable various wearable devices and auxiliary energy supply. Here we report a novel class of mechanical energy harvesters via stress–voltage coupling in electrochemically alloyed electrodes. The device consists of two identical Li-alloyed Si as electrodes, separated by electrolyte-soaked polymer membranes. Bending-induced asymmetric stresses generate chemical potential difference, driving lithium ion flux from the compressed to the tensed electrode to generate electrical current. Removing the bending reverses ion flux and electrical current. Our thermodynamic analysis reveals that the ideal energy-harvesting efficiency of this device is dictated by the Poisson's ratio of the electrodes. For the thin-film-based energy harvester used in this study, the device has achieved a generating capacity of 15%. The device demonstrates a practical use of stress-composition–voltage coupling in electrochemically active alloys to harvest low-grade mechanical energies from various low-frequency motions, such as everyday human activities. PMID:26733282

  9. Electrochemically driven mechanical energy harvesting.

    PubMed

    Kim, Sangtae; Choi, Soon Ju; Zhao, Kejie; Yang, Hui; Gobbi, Giorgia; Zhang, Sulin; Li, Ju

    2016-01-06

    Efficient mechanical energy harvesters enable various wearable devices and auxiliary energy supply. Here we report a novel class of mechanical energy harvesters via stress-voltage coupling in electrochemically alloyed electrodes. The device consists of two identical Li-alloyed Si as electrodes, separated by electrolyte-soaked polymer membranes. Bending-induced asymmetric stresses generate chemical potential difference, driving lithium ion flux from the compressed to the tensed electrode to generate electrical current. Removing the bending reverses ion flux and electrical current. Our thermodynamic analysis reveals that the ideal energy-harvesting efficiency of this device is dictated by the Poisson's ratio of the electrodes. For the thin-film-based energy harvester used in this study, the device has achieved a generating capacity of 15%. The device demonstrates a practical use of stress-composition-voltage coupling in electrochemically active alloys to harvest low-grade mechanical energies from various low-frequency motions, such as everyday human activities.

  10. Theory of electrochemical pattern formation

    NASA Astrophysics Data System (ADS)

    Christoph, J.; Eiswirth, M.

    2002-03-01

    The spatial coupling in electrochemical systems is mediated by ion migration under the influence of the electric field. Since field effects spread very rapidly, every point of an electrode can communicate with every other one practically instantaneously through migration coupling. Based on mathematical potential theory we present the derivation of a generally applicable reaction-migration equation, which describes the coupling via an integral over the whole electrode area. The corresponding coupling function depends only on the geometry of the electrode setup and has been computed for commonly used electrode shapes (such as ring, disk, ribbon or rectangle). The pattern formation observed in electrochemical systems in the bistable, excitable and oscillatory regime can be reproduced in computer simulations, and the types of patterns occurring under different geometries can be rationalized.

  11. A Parylene Bellows Electrochemical Actuator

    PubMed Central

    Li, Po-Ying; Sheybani, Roya; Gutierrez, Christian A.; Kuo, Jonathan T. W.; Meng, Ellis

    2011-01-01

    We present the first electrochemical actuator with Parylene bellows for large-deflection operation. The bellows diaphragm was fabricated using a polyethylene-glycol-based sacrificial molding technique followed by coating in Parylene C. Bellows were mechanically characterized and integrated with a pair of interdigitated electrodes to form an electrochemical actuator that is suitable for low-power pumping of fluids. Pump performance (gas generation rate and pump efficiency) was optimized through a careful examination of geometrical factors. Overall, a maximum pump efficiency of 90% was achieved in the case of electroplated electrodes, and a deflection of over 1.5 mm was demonstrated. Real-time wireless operation was achieved. The complete fabrication process and the materials used in this actuator are bio-compatible, which makes it suitable for biological and medical applications. PMID:21318081

  12. Electrochemically driven mechanical energy harvesting

    NASA Astrophysics Data System (ADS)

    Kim, Sangtae; Choi, Soon Ju; Zhao, Kejie; Yang, Hui; Gobbi, Giorgia; Zhang, Sulin; Li, Ju

    2016-01-01

    Efficient mechanical energy harvesters enable various wearable devices and auxiliary energy supply. Here we report a novel class of mechanical energy harvesters via stress-voltage coupling in electrochemically alloyed electrodes. The device consists of two identical Li-alloyed Si as electrodes, separated by electrolyte-soaked polymer membranes. Bending-induced asymmetric stresses generate chemical potential difference, driving lithium ion flux from the compressed to the tensed electrode to generate electrical current. Removing the bending reverses ion flux and electrical current. Our thermodynamic analysis reveals that the ideal energy-harvesting efficiency of this device is dictated by the Poisson's ratio of the electrodes. For the thin-film-based energy harvester used in this study, the device has achieved a generating capacity of 15%. The device demonstrates a practical use of stress-composition-voltage coupling in electrochemically active alloys to harvest low-grade mechanical energies from various low-frequency motions, such as everyday human activities.

  13. Cathode composition for electrochemical cell

    DOEpatents

    Steunenberg, Robert K.; Martin, Allan E.; Tomczuk, Zygmunt

    1976-01-01

    A high-temperature, secondary electrochemical cell includes a negative electrode containing an alkali metal such as lithium, an electrolyte of molten salt containing ions of that alkali metal and a positive electrode containing a mixture of metallic sulfides. The positive electrode composition is contained within a porous structure that permits permeation of molten electrolyte and includes a mixture of about 5% to 30% by weight Cu.sub.2 S in FeS.

  14. Solid state electrochemical current source

    DOEpatents

    Potanin, Alexander Arkadyevich; Vedeneev, Nikolai Ivanovich

    2002-04-30

    A cathode and a solid state electrochemical cell comprising said cathode, a solid anode and solid fluoride ion conducting electrolyte. The cathode comprises a metal oxide and a compound fluoride containing at least two metals with different valences. Representative compound fluorides include solid solutions of bismuth fluoride and potassium fluoride; and lead fluoride and potassium fluoride. Representative metal oxides include copper oxide, lead oxide, manganese oxide, vanadium oxide and silver oxide.

  15. [Electrochemical methods for biomedical investigations].

    PubMed

    Shumyantseva, V V; Bulko, T V; Suprun, E V; Kuzikov, A V; Agafonova, L E; Archakov, A I

    2015-01-01

    In the review, authors discussed recently published experimental data concerning highly sensitive electrochemical methods and technologies for biomedical investigations in the postgenomic era. Developments in electrochemical biosensors systems for the analysis of various bio objects are also considered: cytochrome P450s, cardiac markers, bacterial cells, the analysis of proteins based on electro oxidized amino acids as a tool for analysis of conformational events. The electroanalysis of catalytic activity of cytochromes P450 allowed developing system for screening of potential substrates, inhibitors or modulators of catalytic functions of this class of hemoproteins. The highly sensitive quartz crystal microbalance (QCM) immunosensor has been developed for analysis of bio affinity interactions of antibodies with troponin I in plasma. The QCM technique allowed real-time monitoring of the kinetic differences in specific interactions and nonspecific sorption, with out multiple labeling procedures and separation steps. The affinity binding process was characterized by the association (ka) and the dissociation (kd) kinetic constants and the equilibrium association (K) constant, calculated using experimental data. Based on the electroactivity of bacterial cells, the electrochemical system for determination of sensitivity of the microbial cells to antibiotics cefepime, ampicillin, amikacin, and erythromycin was proposed. It was shown that the minimally detectable cell number corresponds to 106 CFU per electrode. The electrochemical method allows estimating the degree of E.coli JM109 cells resistance to antibiotics within 2-5 h. Electrosynthesis of polymeric analogs of antibodies for myoglobin (molecularly imprinted polymer, MIP) on the surface of graphite screen-printed electrodes as sensor elements with o- phenylenediamine as the functional monomer was developed. Molecularly imprinted polymers demonstrate selective complementary binding of a template protein molecule

  16. Materials for Electrochemical Energy Storage

    NASA Astrophysics Data System (ADS)

    Johannes, Michelle

    2013-03-01

    Electrochemical energy storage is a primary concern of both the consumer and public energy sectors. Energy, once generated, must be stored, transported and retrieved efficiently. This is commonly done through the use of various kinds of batteries and recently through the use of capacitors. Optimal energy storage involves the complete electrochemical system, but many of the performance properties can be understood in terms of the constituent materials that make up the anode, cathode and electrolyte. In this talk will give a brief overview of electrochemical energy storage systems and the role of materials in improving them. Using computational methods as a framework, I will discuss how discuss how macroscopic properties, such as capacity, conductivity, voltage, and stability are determined by fundamental materials properties at the quantum mechanical level. Using the knowledge gained from understanding the underlying processes, I will discuss some common battery materials, such as LiFePO4, layered transition metal oxides, and oxide electrolyte materials. I will show how predictions for better materials can be made using computational tools to save time and money by circumventing expensive screening in the laboratory. I will also discuss how tailoring the morphology of materials, for example by synthesizing at the nanoscale, can have extreme benefits for battery materials performance.

  17. Compacted carbon for electrochemical cells

    DOEpatents

    Greinke, R.A.; Lewis, I.C.

    1997-10-14

    This invention provides compacted carbon that is useful in the electrode of an alkali metal/carbon electrochemical cell of improved capacity selected from the group consisting of: (a) coke having the following properties: (1) an x-ray density of at least 2.00 grams per cubic centimeters, (2) a closed porosity of no greater than 5%, and (3) an open porosity of no greater than 47%; and (b) graphite having the following properties: (1) an x-ray density of at least 2.20 grams per cubic centimeters, (2) a closed porosity of no greater than 5%, and (3) an open porosity of no greater than 25%. This invention also relates to an electrode for an alkali metal/carbon electrochemical cell comprising compacted carbon as described above and a binder. This invention further provides an alkali metal/carbon electrochemical cell comprising: (a) an electrode as described above, (b) a non-aqueous electrolytic solution comprising an organic aprotic solvent and an electrolytically conductive salt and an alkali metal, and (c) a counter electrode. 10 figs.

  18. Compacted carbon for electrochemical cells

    DOEpatents

    Greinke, Ronald Alfred; Lewis, Irwin Charles

    1997-01-01

    This invention provides compacted carbon that is useful in the electrode of an alkali metal/carbon electrochemical cell of improved capacity selected from the group consisting of: (a) coke having the following properties: (i) an x-ray density of at least 2.00 grams per cubic centimeters, (ii) a closed porosity of no greater than 5%, and (iii) an open porosity of no greater than 47%; and (b) graphite having the following properties: (i) an x-ray density of at least 2.20 grams per cubic centimeters, (ii) a closed porosity of no greater than 5%, and (iii) an open porosity of no greater than 25%. This invention also relates to an electrode for an alkali metal/carbon electrochemical cell comprising compacted carbon as described above and a binder. This invention further provides an alkali metal/carbon electrochemical cell comprising: (a) an electrode as described above, (b) a non-aqueous electrolytic solution comprising an organic aprotic solvent and an electrolytically conductive salt and an alkali metal, and (c) a counterelectrode.

  19. Correlative Multimodal Probing of Ionically-Mediated Electromechanical Phenomena in Simple Oxides: Reversible and Irreversible Electrochemical Processes in NiO

    SciTech Connect

    Kim, Yunseok; Strelcov, Evgheni; Hwang, In Rok; Choi, Taekjib; Park, Bae Ho; Jesse, Stephen; Kalinin, Sergei V

    2013-01-01

    The interplay between the ionic and electronic transport in NiO is explored on the nanoscale using correlative imaging by first-order reversal curve measurements in current-voltage and electrochemical strain microscopy. Electronic current and electromechanical response are observed in reversible and electroforming regime. These studies provide insight into nanoscale mechanisms of electroresistive phenomena in NiO and establish universal method to study interplay between the ionic and electronic transport and electrochemical transformations in mixed electronic-ionic conductors.

  20. Electrochemical synthesis of gold nanoparticles on the surface of multi-walled carbon nanotubes with glassy carbon electrode and their application

    NASA Astrophysics Data System (ADS)

    Song, Y. Z.; Li, X.; Song, Y.; Cheng, Z. P.; Zhong, H.; Xu, J. M.; Lu, J. S.; Wei, C. G.; Zhu, A. F.; Wu, F. Y.; Xu, J.

    2013-01-01

    Gold nanoparticles on the surface of multi-walled carbon nanotubes with glassy carbon electrode were prepared using electrochemical synthesis method. The thin films of gold Nanoparticles/multi-walled carbon nanotubes were characterized by scanning electron microscopy, powder X-ray diffraction, and cyclic voltammetry. Electrochemical behavior of adrenaline hydrochloride at gold nanoparticles/multi-walled carbon nanotube modified glassy carbon electrode was investigated. A simple, sensitive, and inexpensive method for determination of adrenaline hydrochloride was proposed.

  1. Electronic Blending in Virtual Microscopy

    ERIC Educational Resources Information Center

    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…

  2. One-Step Electrochemical Preparation of Multilayer Graphene Functionalized with Nitrogen.

    PubMed

    Ustavytska, Olena; Kurys, Yaroslav; Koshechko, Vyacheslav; Pokhodenko, Vitaly

    2017-12-01

    A new environmentally friendly one-step method for producing multilayer (preferably 7-9 layers) nitrogen-doped graphene (N-MLG) with a slight amount of oxygen-containing defects was developed. The approach is based on the electrochemical exfoliation of graphite electrode in the presence of azide ions under the conditions of electrolysis with pulse changing of the electrode polarization potential. It was found that usage of azide anions lead not only to the exfoliation of graphite but also to the simultaneous functionalization of graphene sheets by nitrogen atoms (as a result of electrochemical decomposition of azide anions with ammonia evolution). Composition, morphology, structure, and electrochemical properties of N-MLG were characterized by C,H,N analysis, transmission electron microscopy, atomic force microscopy, FTIR, UV-Vis, and Raman spectroscopy, as well as cyclic voltammetry. The perspective of using N-MLG as oxygen reduction reaction electrocatalyst and for the electrochemical analysis of biomarkers (dopamine, ascorbic acid, and uric acid) in their mixtures was shown.

  3. Time-Resolved Chemical Mapping in Light-Emitting Electrochemical Cells.

    PubMed

    Jafari, Mohammad Javad; Liu, Jiang; Engquist, Isak; Ederth, Thomas

    2017-01-25

    An understanding of the doping and ion distributions in light-emitting electrochemical cells (LECs) is required to approach a realistic conduction model which can precisely explain the electrochemical reactions, p-n junction formation, and ion dynamics in the active layer and to provide relevant information about LECs for systematic improvement of function and manufacture. Here, Fourier-transform infrared (FTIR) microscopy is used to monitor anion density profile and polymer structure in situ and for time-resolved mapping of electrochemical doping in an LEC under bias. The results are in very good agreement with the electrochemical doping model with respect to ion redistribution and formation of a dynamic p-n junction in the active layer. We also physically slow ions by decreasing the working temperature and study frozen-junction formation and immobilization of ions in a fixed-junction LEC device by FTIR imaging. The obtained results show irreversibility of the ion redistribution and polymer doping in a fixed-junction device. In addition, we demonstrate that infrared microscopy is a useful tool for in situ characterization of electroactive organic materials.

  4. Passivation dynamics in the anisotropic deposition and stripping of bulk magnesium electrodes during electrochemical cycling

    SciTech Connect

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

    2015-08-10

    Rechargeable magnesium (Mg) batteries show promise for use as a next generation technology for high-density energy storage, though 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. Finally, 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.

  5. One-Step Electrochemical Preparation of Multilayer Graphene Functionalized with Nitrogen

    NASA Astrophysics Data System (ADS)

    Ustavytska, Olena; Kurys, Yaroslav; Koshechko, Vyacheslav; Pokhodenko, Vitaly

    2017-03-01

    A new environmentally friendly one-step method for producing multilayer (preferably 7-9 layers) nitrogen-doped graphene (N-MLG) with a slight amount of oxygen-containing defects was developed. The approach is based on the electrochemical exfoliation of graphite electrode in the presence of azide ions under the conditions of electrolysis with pulse changing of the electrode polarization potential. It was found that usage of azide anions lead not only to the exfoliation of graphite but also to the simultaneous functionalization of graphene sheets by nitrogen atoms (as a result of electrochemical decomposition of azide anions with ammonia evolution). Composition, morphology, structure, and electrochemical properties of N-MLG were characterized by C,H,N analysis, transmission electron microscopy, atomic force microscopy, FTIR, UV-Vis, and Raman spectroscopy, as well as cyclic voltammetry. The perspective of using N-MLG as oxygen reduction reaction electrocatalyst and for the electrochemical analysis of biomarkers (dopamine, ascorbic acid, and uric acid) in their mixtures was shown.

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

    PubMed

    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.

  7. Effect of surfactant on the electrochemical performance of graphene/iron oxide electrode for supercapacitor

    NASA Astrophysics Data System (ADS)

    Ghasemi, Shahram; Ahmadi, Fatemeh

    2015-09-01

    In this study, reduced graphene oxide- Fe3O4 (RGO-Fe3O4) nanocomposite is fabricated using simple electrophoretic deposition (EPD) method followed by an electrochemical reduction process. It is characterized using atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and scanning electron microscopy. Fe3O4 nanoparticles with 20-50 nm in diameter are uniformly formed on RGO. Electrochemical properties of nanocomposite are characterized by cyclic voltammetery, galvanostatic charge/discharge and electrochemical impedance spectroscopy. According to the galvanostatic charge/discharge analysis, RGO-Fe3O4/SS presents specific capacitance (Cs) of 154 F g-1 at current density of 1 A g-1, which is higher than that of RGO/SS (81 F g-1) in Na2SO4 electrolyte. Also, the electrochemical behaviors show that addition of three kind of surfactant, i.e. sodium dodecyl sulphate, cetyltrimethylammonium bromide, t-octyl phenoxy polyethoxyethanol (Triton X-100) to Na2SO4 aqueous solution can improve the Cs of RGO-Fe3O4/SS electrodes. RGO-Fe3O4/SS in Na2SO4 electrolyte containing Triton X-100 shows maximum Cs of 236 F g-1 at 1 A g-1 which retains 97% of initial capacitance after 500 cycles.

  8. Controllable synthesis of metal hydroxide and oxide nanostructures by ionic liquids assisted electrochemical corrosion method

    NASA Astrophysics Data System (ADS)

    Liu, Na; Wu, Di; Wu, Haoxi; Luo, Fang; Chen, Ji

    2008-08-01

    Cu(OH) 2 nanowires have been synthesized by anodic oxidation of copper through a simple electrolysis process employing ionic liquid as an electrolyte. Controlling the electrochemical conditions can qualitatively modulate the lengths, amounts, and shapes of Cu(OH) 2 nanostructures. A rational mechanism based on coordination self-assembly and oriented attachment is proposed for the selective formation of the polycrystalline Cu(OH) 2 nanowires. In addition, the FeOOH nanoribbons, Ni(OH) 2 nanosheets, and ZnO nanospheres were also synthesized by this route, indicative of the universality of the electrochemical route presented herein. The morphologies and structures of the synthesized nanostructures have been characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), and thermogravimetric (TG).

  9. Highly sensitive and selective electrochemical dopamine sensing properties of multilayer graphene nanobelts

    NASA Astrophysics Data System (ADS)

    Karthick Kannan, Padmanathan; Moshkalev, Stanislav A.; Sekhar Rout, Chandra

    2016-02-01

    In the present study, we report the electrochemical sensing property of multi-layer graphene nanobelts (GNBs) towards dopamine (DA). GNBs are synthesized from natural graphite and characterized by using techniques like field-emission scanning electron microscopy, atomic force microscopy and Raman spectroscopy. An electrochemical sensor based on GNBs is developed for the detection of DA. From the cyclic voltammetry and amperometry studies, it is found that GNBs possess excellent electrocatalytic activity towards DA molecules. The developed DA sensor showed a sensitivity value of 0.95 μA μM-1 cm-2 with a linear range of 2 μM to 0.2 mM. The interference data exhibited that GNB is highly selective to DA even in the presence of common interfering species like ascorbic acid, uric acid, glucose and lactic acid.

  10. Scanning Tunneling Microscopy, Atomic Force Microscopy, and Related Techniques

    DTIC Science & Technology

    1992-02-26

    primary surface contaminants on electrochemically etched tunpten STM tips as CO. graphite, WC, and tungsten oxide (B55). Several unusual STM tips...the energy density of states by a contamination -induced peak, charging of electron traps, and resonant tunneling in a double- barier quantum well...inequivalent molecules in the unit cell of a free standing tetracene crystal (D371). Atomic resolution on different faces of the conductive perylene radical

  11. Microfluidic chip integrated with flexible PDMS-based electrochemical cytosensor for dynamic analysis of drug-induced apoptosis on HeLa cells.

    PubMed

    Cao, Jun-Tao; Zhu, Ying-Di; Rana, Rohit Kumar; Zhu, Jun-Jie

    2014-01-15

    A novel microfluidic platform integrated with a flexible PDMS-based electrochemical cytosensor was developed for real-time monitoring of the proliferation and apoptosis of HeLa cells. The PDMS-gold film, which had a conductive smooth surface and was semi-transparent, facilitated electrochemical measurements and optical microscope observations. We observed distinct increases and decreases in peak current intensity, corresponding to cell proliferation in culture medium and apoptosis in the presence of an anticancer drug, respectively. This electrochemical analysis method permitted real-time, label-free monitoring of cell behavior, and the electrochemical results were confirmed with optical microscopy. The flexible microfluidic electrochemical platform presented here is suitable for on-site monitoring of cell behavior in microenvironments.

  12. Electrochemical immunochip sensor for aflatoxin M1 detection.

    PubMed

    Parker, Charlie O; Lanyon, Yvonne H; Manning, Mary; Arrigan, Damien W M; Tothill, Ibtisam E

    2009-07-01

    An investigation into the fabrication, electrochemical characterization, and development of a microelectrode array (MEA) immunosensor for aflatoxin M(1) is presented in this paper. Gold MEAs (consisting of 35 microsquare electrodes with 20 microm x 20 microm dimensions and edge-to-edge spacing of 200 microm) together with on-chip reference and counter electrodes were fabricated using standard photolithographic methods. The MEAs were then characterized by cyclic voltammetry, and the behavior of the on-chip electrodes were evaluated. The microarray sensors were assessed for their applicability to the development of an immunosensor for the analysis of aflatoxin M(1) directly in milk samples. Following the sensor surface silanization, antibodies were immobilized by cross-linking with 1,4-phenylene diisothiocyanate (PDITC). Surface characterization was conducted by electrochemistry, fluorescence microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). A competitive enzyme linked immunosorbent assay (ELISA) assay format was developed on the microarray electrode surface using the 3,3,5',5'-tetramethylbenzidine dihyrochloride (TMB)/H(2)O(2) electrochemical detection scheme with horseradish peroxidase (HRP) as the enzyme label. The performance of the assay and the microarray sensor were characterized in pure buffer conditions before applying to the milk samples. With the use of this approach, the detection limit for aflatoxin M(1) in milk was estimated to be 8 ng L(-1), with a dynamic detection range of 10-100 ng L(-1), which meets present legislative limits of 50 ng L(-1). The milk interference with the sensor surface was also found to be minimal. These devices show high potential for development of a range of new applications which have previously only been detected using elaborate instrumentation.

  13. Multi-contrast Photoacoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Yao, Junjie

    Photoacoustic microscopy is a hybrid imaging modality with high spatial resolution, moderate imaging depth, excellent imaging contrast and functional imaging capability. Taking full advantage of this powerful weapon, we have investigated different anatomical, functional, flow dynamic and metabolic parameter measurements using photoacoustic microscopy. Specifically, Evans-blue dye was used to enhance photoacoustic microscopy of capillaries; label-free transverse and axial blood flow was measured based on bandwidth broadening and time shift of the photoacoustic signals; metabolic rate of oxygen was quantified in vivo from all the five parameters measured by photoacoustic microcopy; whole cross-sectional imaging of small intestine was achieved on a double-illumination photoacoustic microscopy with extended depth of focus and imaging depth; hemodynamic imaging was performed on a MEMS-mirror enhanced photoacoustic microscopy with a cross-sectional imaging rate of 400 Hz. As a maturing imaging technique, PAM is expected to find new applications in both fundamental life science and clinical practice.

  14. Studies in scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Sarid, Dror

    1995-06-01

    The following is a final report on our work in the field of Scanning Probe Microscopy (SPM), which has been funded by the AFOSR under Contract #F49620-92-J-0164. The AFOSR funding was instrumental in the establishment of a multi-lab facility at the Optical Sciences Center, which performs research in SPM using two ultrahigh vacuum (UHV) STM facilities, and several Atomic Force Microscopy (AFM) facilities. The fabrication and characterization work performed in the SPM Laboratory is supplemented by infrared (IR) spectroscopy, high resolution transmission electron microscopy (HRTEM), and scanning electron microscopy (SEM), available in other departments on campus. The report covers the following areas: (1) GaAs and CdSe Structures, (2) Optical Interactions on a nm and nsec Scales, (3) Fullerenes on Gold, (4) Fullerenes on MoS2, (5) Fullerenes on Si, (6) SiC, (7) Nanotubes, (8) Scanning Force Microscopy, and (9) Biology.

  15. Chip-scale microscopy imaging.

    PubMed

    Zheng, Guoan

    2012-08-01

    Chip-scale microscopy imaging platforms are pivotal for improving the efficiency of modern biomedical and bioscience experiments. Their integration with other lab-on-a-chip techniques would allow rapid, reliable and high-throughput sample analysis for applications in diverse disciplines. In typical chip-scale microscopy imaging platforms, the light path can be generalized to the following steps: photons leave the light source, interact with the sample and finally are detected by the sensor. Based on the light path of these platforms, the current review aims to provide some insights on design strategies for chip-scale microscopy. Specifically, we analyze current chip-scale microscopy approaches from three aspects: illumination design, sample manipulation and substrate/imager modification. We also discuss some opportunities for future developments of chip-scale microscopy, such as time multiplexed structured illumination and hydrodynamic focusing for high throughput sample manipulation.

  16. Atomic force microscopy combined with optical microscopy for cells investigation.

    PubMed

    Cascione, Mariafrancesca; de Matteis, Valeria; Rinaldi, Rosaria; Leporatti, Stefano

    2017-01-01

    This review reports on the combined use of the atomic force microscopy (AFM) and several type of optical/fluorescence/laser scanning microscopy for investigating cells. It is shown that the hybrid systems of AFM with optical-derived microscopies enable to study in detail cell surface properties (such as topography), their mechanical properties (e.g., Young's modulus) mechanotransduction phenomena and allow to gain insight into biological-related pathways and mechanisms in the complex nanoworld of cells. Microsc. Res. Tech. 80:109-123, 2017. © 2016 Wiley Periodicals, Inc.

  17. Characterization of thin film semiconductors by scanning probe microscopy and tunneling spectroscopy

    NASA Astrophysics Data System (ADS)

    Gichuhi, Anthony

    We have used scanning tunneling microscopy, atomic force microscopy, tunneling spectroscopy, resonance Raman spectroscopy and electrochemistry to study the electrosynthesis of II-VI compound semiconductors with special emphasis on ZnS, CdS, and HgS. This dissertation will focus mainly on the electrochemical and scanning probe (STM and AFM) applications to these compounds, in addition to novel materials such as CoSb. We hope to understand the structural, as well optical properties of these materials. Finally, we hope to develop a recipe for the electrosynthesis of high quality semiconductor films. In Chapter 2, we report an electrochemical, scanning probe microscopic and Raman spectroscopic investigation of thin US films grown by electrochemical atomic layer epitaxy (EC-ALE) aimed at understanding the role played by the order of deposition on film quality. In Chapter 3, we report a study of electrosynthesized CdS-HgS heterojunctions using scanning tunneling microscopy (STM), photoluminescence spectroscopy (PL), and electrochemistry. US thin films were grown by electrochemical atomic layer epitaxy onto Au(111) substrates and were terminated with a single HgS monolayer. In Chapter 4, the structure and chemical composition of electrosynthesized ZnS thin films on Au(111) substrates grown by alternating underpotential deposition and oxidative adsorption cycles of S and Zn from solution precursors was studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). In Chapter 5, conditions for the growth of. stable mercury sulfide (HgS) monolayers on Au(111) surfaces using electrochemical atomic layer epitaxy have been investigated. HgS thin films were characterized by X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Chapter 6: This chapter describes the use of resonance Raman spectroscopy to characterize thin films of the II-VI compound semiconductors electrosynthesized on metal surfaces. We describe how resonance

  18. Shock-activated electrochemical power supplies

    DOEpatents

    Benedick, W.B.; Graham, R.A.; Morosin, B.

    1987-04-20

    A shock-activated electrochemical power supply is provided which is initiated extremely rapidly and which has a long shelf life. Electrochemical power supplies of this invention are initiated much faster than conventional thermal batteries. Power supplies of this invention comprise an inactive electrolyte and means for generating a high-pressure shock wave such that the shock wave is propagated through the electrolyte rendering the electrolyte electrochemically active. 2 figs.

  19. Shock-activated electrochemical power supplies

    DOEpatents

    Benedick, William B.; Graham, Robert A.; Morosin, Bruno

    1988-01-01

    A shock-activated electrochemical power supply is provided which is initiated extremely rapidly and which has a long shelf life. Electrochemical power supplies of this invention are initiated much faster than conventional thermal batteries. Power supplies of this invention comprise an inactive electrolyte and means for generating a high-pressure shock wave such that the shock wave is propagated through the electrolytes rendering the electrolyte electrochemically active.

  20. Shock-activated electrochemical power supplies

    DOEpatents

    Benedick, W.B.; Graham, R.A.; Morosin, B.

    1988-11-08

    A shock-activated electrochemical power supply is provided which is initiated extremely rapidly and which has a long shelf life. Electrochemical power supplies of this invention are initiated much faster than conventional thermal batteries. Power supplies of this invention comprise an inactive electrolyte and means for generating a high-pressure shock wave such that the shock wave is propagated through the electrolytes rendering the electrolyte electrochemically active. 2 figs.

  1. Electrochemical components employing polysiloxane-derived binders

    DOEpatents

    Delnick, Frank M.

    2013-06-11

    A processed polysiloxane resin binder for use in electrochemical components and the method for fabricating components with the binder. The binder comprises processed polysiloxane resin that is partially oxidized and retains some of its methyl groups following partial oxidation. The binder is suitable for use in electrodes of various types, separators in electrochemical devices, primary lithium batteries, electrolytic capacitors, electrochemical capacitors, fuel cells and sensors.

  2. Enhanced solar photocurrent of LaTaON2 photoanodes via electrochemical treatment

    NASA Astrophysics Data System (ADS)

    Huang, Huiting; Li, Zhaosheng

    2017-03-01

    Having a theoretical 18.5% solar-to-hydrogen efficiency, LaTaON2 has emerged as a promising photoanode material. However, its performance is crucially limited by low photocurrent in the past reports. To improve its solar photocurrent, a negative electrochemical treatment was applied for the LaTaON2 photoanode. The sample powder was successfully synthesized by a flux assisted-nitridation with precursor derived from solid state sintering. And the LaTaON2 photoanodes were fabricated by electrophoretic deposition with a post-necking procedure. The solar photocurrent of as-fabricated LaTaON2 photoanode has increased to 1.2 mA cm-2 at 1.6 VRHE after the negative electrochemical treatment in the dark. The photoanodes with and without the electrochemical treatment were investigated by scanning electron microscopy (SEM), Mott–Schottky test, transient photocurrent and open-circuit photovoltage. The results showed that the enhancement maybe ascribed to the soared carrier density and elimination of surface recombination centre. Therefore it is proposed that the electrochemical treatment eliminates the surface recombination centre of the oxynitrides leading to increased solar photocurrent. It was also found that the SrTaO2N photoanode had increased photocurrent after the electrochemical treatment. This study provides a facile and general way to improve the solar water-splitting current of photoanodes.

  3. Multiscale Electrochemical Investigation of the Corrosion Resistance of Various Alloys Used in Dental Prostheses

    NASA Astrophysics Data System (ADS)

    Iacoban, Sorin; Mareci, Daniel; Bolat, Georgiana; Munteanu, Corneliu; Souto, Ricardo Manuel

    2015-04-01

    The electrochemical behavior of Ag-Pd (Paliag), Ni-Cr (Heraenium NA), and Co-Cr (Heraenium CE) alloys used in dental prosthetics construction of crowns and bridges was studied in 0.9 pct NaCl solution at 298 K (25 °C). The localized electrochemical characteristics related to corrosion resistance and eventual breakdown of the protecting oxide layers were investigated by scanning electrochemical microscopy (SECM), whereas potentiodynamic polarization and electrochemical impedance spectroscopy techniques were employed to establish oxide stability. When the corrosion resistance of the alloys was evaluated by means of the corrosion current value determined around their corresponding open circuit potential in 0.9 pct NaCl solution, good protection can be expected resulting from their spontaneous passivation (low current densities in the order of tenths of μA cm-2). The polarization resistance of all the samples increased with immersion time, in the sequence Ag-Pd < Heraenium NA < Heraenium CE. Yet, increased electrochemical activity was detected with SECM when the alloys were polarized at +0.40 V SCE, a value that may be eventually experienced in the human body. Although a passivation mechanism was still operating in the chromium-containing alloys, oxide dissolution and precipitation of corrosion products occurred on Ag-Pd instead.

  4. Chemical and electrochemical study of fabrics coated with reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Molina, J.; Fernández, J.; del Río, A. I.; Bonastre, J.; Cases, F.

    2013-08-01

    Polyester fabrics coated with reduced graphene oxide (RGO) have been obtained and later characterized by means of chemical and electrochemical techniques. X-ray photoelectron spectroscopy showed a decrease of the oxygen content as well as an increase of the sp2 fraction after chemical reduction of graphene oxide (GO). The electrical conductivity was measured by electrochemical impedance spectroscopy (EIS) and showed a decrease of 5 orders of magnitude in the resistance (Ω) when GO was reduced to RGO. The phase angle also changed from 90° for PES-GO (capacitative behavior) to 0° for RGO coated fabrics (resistive behavior). In general an increase in the number of RGO layers produced an increase of the conductivity of the fabrics. EIS measurements in metal/sample/electrolyte configuration showed better electrocatalytic properties and faster diffusion rate for RGO specimens. Scanning electrochemical microscopy was employed to test the electroactivity of the different fabrics obtained. The sample coated with GO was not conductive since negative feedback was obtained. When GO was reduced to RGO the sample behaved like a conducting material since positive feedback was obtained. Approach curves indicated that the redox mediator had influence on the electrochemical response. The Fe(CN)63-/4- redox mediator produced a higher electrochemical response than Ru(NH3)63+/2+ one.

  5. Structure and Optical Features of Micro/Nanosized Carbon Forms Prepared by Electrochemical Exfoliation

    NASA Astrophysics Data System (ADS)

    Nedilko, Sergii G.; Revo, Sergiy; Chornii, Vitalii; Scherbatskyi, Vasyl; Ivanenko, Kateryna; Nedielko, Maksym; Sementsov, Yurii; Skoryk, Mykola; Nikolenko, Andrii; Strelchuk, Victor

    2017-01-01

    Micro/nanosized carbon materials were prepared by electrochemical exfoliation method in the forms of the colloids and thin films. Scanning electronic microscopy, optical and luminescent microscopy, and Raman scattering and luminescent spectroscopy were applied for characterization of materials. The wide photoluminescence band in the visible spectral region was observed for each of the samples. The shape of the photoluminescence band depends on excitation wavelength and on the size of the particles. At least two components with maxima at 580 and 710 nm can be distinguished in the photoluminescence spectra. The relations between the photoluminescence properties and morphology of the samples have been described and discussed.

  6. Hydroxyapatite/gelatin functionalized graphene oxide composite coatings deposited on TiO2 nanotube by electrochemical deposition for biomedical applications

    NASA Astrophysics Data System (ADS)

    Yan, Yajing; Zhang, Xuejiao; Mao, Huanhuan; Huang, Yong; Ding, Qiongqiong; Pang, Xiaofeng

    2015-02-01

    Graphene oxide cross-linked gelatin was employed as reinforcement fillers in hydroxyapatite coatings by electrochemical deposition process on TiO2 nanotube arrays (TNs). The TNs were grown on titanium by electrochemical anodization in hydrofluoric electrolyte using constant voltage. Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Field emission scanning electron microscopy equipped with energy dispersive X-ray analysis and biological studies were used to characterize the coatings. The corrosion resistance of the coatings was also investigated by electrochemical method in simulated body fluid solution.

  7. Nanomaterial-Based Electrochemical Biosensors and Bioassays

    SciTech Connect

    Liu, Guodong; Mao, Xun; Gurung, Anant; Baloda, Meenu; Lin, Yuehe; He, Yuqing

    2010-08-31

    This book chapter summarizes the recent advance in nanomaterials for electrochemical biosensors and bioassays. Biofunctionalization of nanomaterials for biosensors fabrication and their biomedical applications are discussed.

  8. Apparatus for combinatorial screening of electrochemical materials

    DOEpatents

    A high throughput combinatorial screening method and apparatus for the evaluation of electrochemical materials using a single voltage source is disclosed wherein temperature changes arising from the application of an electrical load to a cell array are used to evaluate the relative electrochemical efficiency of the materials comprising the array. The apparatus may include an array of electrochemical cells that are connected to each other in parallel or in series, an electronic load for applying a voltage or current to the electrochemical cells , and a device , external to the cells, for monitoring the relative temperature of each cell when the load is applied.

    2009-12-15

    A high throughput combinatorial screening method and apparatus for the evaluation of electrochemical materials using a single voltage source (2) is disclosed wherein temperature changes arising from the application of an electrical load to a cell array (1) are used to evaluate the relative electrochemical efficiency of the materials comprising the array. The apparatus may include an array of electrochemical cells (1) that are connected to each other in parallel or in series, an electronic load (2) for applying a voltage or current to the electrochemical cells (1), and a device (3), external to the cells, for monitoring the relative temperature of each cell when the load is applied.

  9. The simulation model of planar electrochemical transducer

    NASA Astrophysics Data System (ADS)

    Zhevnenko, D. A.; Vergeles, S. S.; Krishtop, T. V.; Tereshonok, D. V.; Gornev, E. S.; Krishtop, V. G.

    2016-12-01

    Planar electrochemical systems are very perspective to build modern motion and pressure sensors. Planar microelectronic technology is successfully used for electrochemical transducer of motion parameters. These systems are characterized by an exceptionally high sensitivity towards mechanic exposure due to high rate of conversion of the mechanic signal to electric current. In this work, we have developed a mathematical model of this planar electrochemical system, which detects the mechanical signals. We simulate the processes of mass and charge transfer in planar electrochemical transducer and calculated its transfer function with different geometrical parameters of the system.

  10. Microscopy techniques in flavivirus research.

    PubMed

    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.

  11. Protocol of Electrochemical Test and Characterization of Aprotic Li-O2 Battery.

    PubMed

    Luo, Xiangyi; Wu, Tianpin; Lu, Jun; Amine, Khalil

    2016-07-12

    We demonstrate a method for electrochemical testing of an aprotic Li-O2 battery. An aprotic Li-O2 battery is made of a Li-metal anode, an aprotic electrolyte, and an O2-breathing cathode. The aprotic electrolyte is a solution of lithium salt with aprotic solvent; and porous carbon is commonly used as the cathode substrate. To improve the performance, an electrocatalyst is deposited onto the porous carbon substrate by certain deposition methods, such as atomic layer deposition (ALD) and wet-chemistry reaction. The as-prepared cathode materials are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray absorption near edge structure (XANES). A Swagelok-type cell, sealed in a glass chamber filled with pure O2, is used for the electrochemical test on a battery test system. The cells are tested under either capacity-controlled mode or voltage controlled mode. The reaction products are investigated by electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and Raman spectroscopy to study the possible pathway of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). This protocol demonstrates a systematic and efficient arrangement of routine tests of the aprotic Li-O2 battery, including the electrochemical test and characterization of battery materials.

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

    DOE PAGES

    Strelcov, Evgheni; Yang, Sang Mo; Jesse, Stephen; ...

    2016-04-21

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

  13. Horizontal microscopy in square capillaries

    NASA Astrophysics Data System (ADS)

    Moroz, Pavel E.

    1992-07-01

    Intracellular protoplasmic movements may, due to gravity, have a vertical component greater or different from the horizontal one. This makes horizontal microscopy indispensable in the search for the cellular sensor of gravity. The possibility of the latter being a cell organelle assigns special significance to high-resolution microscopy. A horizontal suction device for picking up a cell and its high-resolution horizontal microscopy in a rectangular capillary may be helpful for detection of gravity-related shifts of cellular organelles in vivo.

  14. Research With Scanning Tip Microscopy

    DTIC Science & Technology

    1991-12-31

    08ro P noiwe bae?041Le Research With Scanning Tip Microscopy AFOSR-89-0498 V AUTHOS)i Professor Dror Sarid 7. PFOUImNG 00ANIZATION NAMEIS) AND...forces and (b) surfaces. UNCLASS UNCLASS UNCLASS UL FINAL REPORT TO THE AFOSR ൱-, to J4ti. r Aat io Research in Scanning Tip Microscopy Dror Sarid Dtst...microscopy have been used to investigate (a) forces and (b) surfaces. a. Forces 1. Dror Sarid , Douglas lams, Volker Weissenberger, and L. Stephen Bell

  15. Soil microstructure and electron microscopy

    NASA Technical Reports Server (NTRS)

    Smart, P.; Fryer, J. R.

    1988-01-01

    As part of the process of comparing Martian soils with terrestial soils, high resolution electron microscopy and associated techniques should be used to examine the finer soil particles, and various techniques of electron and optical microscopy should be used to examine the undisturbed structure of Martian soils. To examine the structure of fine grained portions of the soil, transmission electron microscopy may be required. A striking feature of many Martian soils is their red color. Although the present-day Martian climate appears to be cold, this color is reminiscent of terrestial tropical red clays. Their chemical contents are broadly similar.

  16. Specific features of sample preparation from amorphous aluminum alloys for transmission electron microscopy

    SciTech Connect

    Volkov, P. A.; Todorova, E. V.; Bakhteeva, N. D.; Ivanova, A. G.; Vasil'ev, A. L.

    2011-05-15

    An aluminum amorphous alloy doped with transition (Fe and Ni) and rare earth (La) metals has been used as an object of systematic study of the structural transformations that are characteristic of different methods of sample preparation for transmission electron microscopy (the mechanical tearing of ribbons, electrochemical thinning, and Ar{sup +}-ion etching under different conditions). The results of X-ray diffraction analysis and a calorimetric study of the structure in comparison with electron microscopy data made it possible to determine the optimal method of sample preparation, which ensures minimum distortions in the structure of metastable amorphous alloys with a low crystallization temperature.

  17. Electrochemical Machining of Metal Plates

    SciTech Connect

    Cooper, J F; Evans, M C

    2005-03-04

    Electrochemical machining (ECM) with concentrated sodium chlorate electrolyte was used to rapidly cut a circular groove (13 cm diameter, 0.2 cm wide) through a 0.15 cm thick sheet of steel--thus opening a 5-inch porthole in as little as 10 minutes. The most favorable operating conditions were: T = 22 C; chlorate concentration 600 g NaClO{sub 3}/liter-solution; electric power of 100 A at 10 V; and flow of 0.5 l/s at a pressure drop of 10 kPa (1.5 psi). The porthole may be removed entirely by electrochemical means, or the electrochemical dissolution may continue until only thin membrane remains that is subsequently cut with a utility knife. An array of thermocouples was used to track temperature in the flowing solution and in the trough being machined; the maximum increase in temperature in the trough was 5 C over that of the flowing electrolyte which increased in temperature by 19 C because of power dissipation. ECM is shown feasible for rapid perforation of plates of ferrous and non-ferrous metals using portable equipment and commercial batteries. The technique can be extended to cut perforations of arbitrary shape through non-planar surfaces using a deformable ring cathode. Analysis of the power requirements for electrolyte flow and ECM indicate a total system weight of less than 45 kg (100 lb) using a commercial NiMH battery. The technique is recommended for reduction to practice and demonstration on full scale as an engineering prototype.

  18. Electrochemically reduced graphene oxide-based electrochemical sensor for the sensitive determination of ferulic acid in A. sinensis and biological samples.

    PubMed

    Liu, Linjie; Gou, Yuqiang; Gao, Xia; Zhang, Pei; Chen, Wenxia; Feng, Shilan; Hu, Fangdi; Li, Yingdong

    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 (ks) and electron-transfer coefficient (α) were calculated as 1.12, 1.24s(-1), and 0.40, respectively. Under the optimized conditions, the oxidation peak current was proportional to FA concentration at 8.49 × 10(-8)mol L(-1) to 3.89 × 10(-5)mol L(-1) with detection limit of 2.06 × 10(-8)mol L(-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%.

  19. Studies in Scanning Probe Microscopy.

    DTIC Science & Technology

    2007-11-02

    refereed journals, as well as two books titled Scanning Force Microscopy, With Applications to Electric, Magnetic, and Atomic Forces published by Oxford University Press in 1991 and a revised edition in 1994.

  20. Fluorescence Microscopy of Single Molecules

    ERIC Educational Resources Information Center

    Zimmermann, Jan; van Dorp, Arthur; Renn, Alois

    2004-01-01

    The investigation of photochemistry and photophysics of individual quantum systems is described with the help of a wide-field fluorescence microscopy approach. The fluorescence single molecules are observed in real time.

  1. En face coherence microscopy [Invited

    PubMed Central

    Thouvenin, Olivier; Grieve, Kate; Xiao, Peng; Apelian, Clement; Boccara, A. Claude

    2017-01-01

    En face coherence microscopy or flying spot or full field optical coherence tomography or microscopy (FF-OCT/FF-OCM) belongs to the OCT family because the sectioning ability is mostly linked to the source coherence length. In this article we will focus our attention on the advantages and the drawbacks of the following approaches: en face versus B scan tomography in terms of resolution, coherent versus incoherent illumination and influence of aberrations, and scanning versus full field imaging. We then show some examples to illustrate the diverse applications of en face coherent microscopy and show that endogenous or exogenous contrasts can add valuable information to the standard morphological image. To conclude we discuss a few domains that appear promising for future development of en face coherence microscopy. PMID:28270972

  2. Computer microscopy in lymphoma diagnostics

    NASA Astrophysics Data System (ADS)

    Mozhenkova, A. V.; Tupitsin, N. N.; Frenkel, M. A.; Falaleeva, N. A.; Nikitaev, V. G.; Polyakov, E. V.

    2017-01-01

    The article describes the application of computer microscopy with multi-spectral camera for the comparative characteristics of normal lymphocytes and lymphoid cells in follicular lymphoma. Wavelet functions are used to quantify parameters of the cells nuclei images.

  3. Vertically scanned laser sheet microscopy.

    PubMed

    Dong, Di; Arranz, Alicia; Zhu, Shouping; Yang, Yujie; Shi, Liangliang; Wang, Jun; Shen, Chen; Tian, Jie; Ripoll, Jorge

    2014-01-01

    Laser sheet microscopy is a widely used imaging technique for imaging the three-dimensional distribution of a fluorescence signal in fixed tissue or small organisms. In laser sheet microscopy, the stripe artifacts caused by high absorption or high scattering structures are very common, greatly affecting image quality. To solve this problem, we report here a two-step procedure which consists of continuously acquiring laser sheet images while vertically displacing the sample, and then using the variational stationary noise remover (VSNR) method to further reduce the remaining stripes. Images from a cleared murine colon acquired with a vertical scan are compared with common stitching procedures demonstrating that vertically scanned light sheet microscopy greatly improves the performance of current light sheet microscopy approaches without the need for complex changes to the imaging setup and allows imaging of elongated samples, extending the field of view in the vertical direction.

  4. Electrochemical form grinding. Fnal report

    SciTech Connect

    Stiles, R.W.

    1980-06-01

    Electrochemical form grinding cutting tests were performed on 25 17-4 PH stainless steel bars by a copper resin aluminum oxide wheel formed from a diamond form block. Tests investigated methods of dressing a form into a grinding wheel, nozzle design, optimum machine settings, and tolerance capabilities. The electrolyte was distributed evenly onto the wheel by a form-fitting nozzle, and a minimum of two passes, rough and finish, were made because of current density variations throughout the cut. Tolerance held on the form test samples was +- 0.12 mm on the contour, with an average 0.12 mm overcut.

  5. Electrochemical formation of field emitters

    DOEpatents

    Bernhardt, Anthony F.

    1999-01-01

    Electrochemical formation of field emitters, particularly useful in the fabrication of flat panel displays. The fabrication involves field emitting points in a gated field emitter structure. Metal field emitters are formed by electroplating and the shape of the formed emitter is controlled by the potential imposed on the gate as well as on a separate counter electrode. This allows sharp emitters to be formed in a more inexpensive and manufacturable process than vacuum deposition processes used at present. The fabrication process involves etching of the gate metal and the dielectric layer down to the resistor layer, and then electroplating the etched area and forming an electroplated emitter point in the etched area.

  6. Electrochemical Nanoparticle-Based Sensors

    NASA Astrophysics Data System (ADS)

    Wang, Joseph

    Electrochemical devices are extremely useful for delivering analytical information in a fast, simple, and low-cost fashion, and are thus uniquely qualified for meeting the demands of point-of-care diagnostics. In particular, nanoparticles offer elegant ways for interfacing biomolecular recognition events with electronic signal transduction, for dramatically amplifying the resulting electrical response, and for designing novel coding strategies. Nanoparticles, such as colloidal gold or inorganic nanocrystals, offer considerable promise as quantitation tags for biological assays owing to their unique amplification and coding capabilities.

  7. Nanoelectrode array for electrochemical analysis

    DOEpatents

    Yelton, William G.; Siegal, Michael P.

    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.

  8. Electrochemical storage cell or battery

    SciTech Connect

    Mennicke, S.; Liebermann, K.; Reiss, K.

    1983-11-08

    Electrochemical storage cell is disclosed, based on alkali metal and chalcogen as reactants with an anode space and a cathode space separated by an alkali ion conducting solid electrolyte wall and bounded by a cell wall of light metal such as aluminum. A strongly adhering metal coating is applied to the area of the light metal wall in contact with one of the reactants. The metal coating chemically reacts to form a sulfide without materially affecting conductivity of the cell wall of light metal and without material increase in the internal resistance of the storage cell.

  9. Electrolyte composition for electrochemical cell

    DOEpatents

    Vissers, Donald R.; Tomczuk, Zygmunt; Anderson, Karl E.; Roche, Michael F.

    1979-01-01

    A high-temperature, secondary electrochemical cell that employs FeS as the positive electrode reactant and lithium or lithium alloy as the negative electrode reactant includes an improved electrolyte composition. The electrolyte comprises about 60-70 mole percent LiCl and 30-40 percent mole percent KCl which includes LiCl in excess of the eutectic composition. The use of this electrolyte suppresses formation of the J phase and thereby improves the utilization of positive electrode active material during cell cycling.

  10. High temperature sealed electrochemical cell

    SciTech Connect

    Valentin Chung, Brice Hoani; Burke, Paul J.; Sadoway, Donald R.

    2015-10-06

    A cell for high temperature electrochemical reactions is provided. The cell includes a container, at least a portion of the container acting as a first electrode. An extension tube has a first end and a second end, the extension tube coupled to the container at the second end forming a conduit from the container to said first end. A second electrode is positioned in the container and extends out of the container via the conduit. A seal is positioned proximate the first end of the extension tube, for sealing the cell.

  11. Preparation and characterization of zinc oxide nanoparticles and their sensor applications for electrochemical monitoring of nucleic acid hybridization.

    PubMed

    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).

  12. Magnetic Force Microscopy in Liquids.

    PubMed

    Ares, Pablo; Jaafar, Miriam; Gil, Adriana; Gómez-Herrero, Julio; Asenjo, Agustina

    2015-09-01

    In this work, the use of magnetic force microscopy (MFM) to acquire images of magnetic nanostructures in liquid environments is presented. Optimization of the MFM signal acquisition in liquid media is performed and it is applied to characterize the magnetic signal of magnetite nanoparticles. The ability for detecting magnetic nanostructures along with the well-known capabilities of atomic force microscopy in liquids suggests potential applications in fields such as nanomedicine, nanobiotechnology, or nanocatalysis.

  13. Confocal microscopy in transmitted light

    NASA Astrophysics Data System (ADS)

    Dodt, Hans-Ulrich; Becker, Klaus

    2003-10-01

    We developed a confocal microscope for transmitted light to visualize fine details in phase objects like unstained biological specimens. The main difficulty of confocal microscopy in transmission is the alignment of illumination and detector pinholes. This alignment was achieved by using "electronic pinholes" on the detector side. As a first step, we were able to image cells in onion skin at greater depths and with higher resolution than by using conventional microscopy.

  14. Low Voltage Scanning Electron Microscopy

    DTIC Science & Technology

    1988-10-01

    Microscopy List of Keywords ,Scanning electron microscopy SEM X -ray .Micoranalysis EDX/EDS -%Low voltage , High resolution -Ceramic surfaces Supported...energy component normal to the surface). (a) Applications to x -ray microanalysis The essential problem leading to the specification of a LVSEM is...illustrated (Fig.l), for a conventional microprobe operated with 20nA probe current, by the contrast of the alumunium (K) x -ray signal as the probe is scanned

  15. Non-aqueous electrolytes for electrochemical cells

    DOEpatents

    Zhang, Zhengcheng; Dong, Jian; Amine, Khalil

    2016-06-14

    An electrolyte electrochemical device includes an anodic material and an electrolyte, the electrolyte including an organosilicon solvent, a salt, and a hybrid additiving having a first and a second compound, the hybrid additive configured to form a solid electrolyte interphase film on the anodic material upon application of a potential to the electrochemical device.

  16. Porous nickel oxide films for electrochemical capacitors

    SciTech Connect

    Liu, K.C.; Anderson, M.A.

    1995-12-31

    NiO/Ni composite thin films consisting of nano-sized particles have been found to perform as good electrodes in electrochemical capacitor applications. These films can provide a specific capacitance of 25--40 F/g. The low cost of raw materials and easy manufacturing process of this system should allow one to produce low-cost electrochemical capacitors.

  17. Method for making an electrochemical cell

    DOEpatents

    Tuller, Harry L.; Kramer, Steve A.; Spears, Marlene A.; Pal, Uday B.

    1996-01-01

    An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is provided.

  18. Electrochemical synthesis of nanosized hydroxyapatite by pulsed direct current method

    SciTech Connect

    Nur, Adrian; Rahmawati, Alifah; Ilmi, Noor Izzati; Affandi, Samsudin; Widjaja, Arief

    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.

  19. Solid oxide electrochemical reactor science.

    SciTech Connect

    Sullivan, Neal P.; Stechel, Ellen Beth; Moyer, Connor J.; Ambrosini, Andrea; Key, Robert J.

    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.

  20. Electrochemical application of DNA biosensors

    NASA Astrophysics Data System (ADS)

    Mascini, M.; Lucarelli, F.; Palchetti, I.; Marrazza, G.

    2001-09-01

    Disposable electrochemical DNA-based biosensors are reviewed; they have been used for the determination of low- molecular weight compounds with affinity for nucleic acids and for the detection of hybridization reaction. The first application is related to the molecular interaction between surface-linked DNA and pollutants or drugs, in order to develop a simple device for rapid screening of toxic compounds. The determination of such compounds was measured by their effect simple device for rapid screening of toxic compounds. The determination of such compounds was measured by their effect on the oxidation signal of the guanine peak of calf thymus DNA immobilized on the electrode surface and investigated by chronopotentiometric or voltammetric analysis. Applicability to river and wastewater sample is demonstrated. Moreover, disposable electrochemical sensors for the detection of a specific sequence of DNA were realized by immobilizing synthetic single-stranded oligonucleotides onto a graphite screen-printed electrode. The probes because hybridized with different concentrations of complementary sequences present in the sample. The hybrids formed on the electrode surface were evaluated by chronopotentiometric analysis using daunomycin as the indicator of the hybridization reaction. The hybridization was also performed using real samples. Application to apolipoprotein E is described, in this case samples have to be amplified by PCR and then analyzed by the DNA biosensor. The extension of such procedures to samples of environmental interest or to contamination of food is discussed.

  1. Buffered Electrochemical Polishing of Niobium

    SciTech Connect

    Gianluigi Ciovati; Tian, Hui; Corcoran, Sean

    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.

  2. Space Electrochemical Research and Technology

    NASA Technical Reports Server (NTRS)

    Wilson, Richard M. (Compiler)

    1996-01-01

    Individual papers presented at the conference address the following topics: development of a micro-fiber nickel electrode for nickel-hydrogen cell, high performance nickel electrodes for space power application, bending properties of nickel electrodes for nickel-hydrogen batteries, effect of KOH concentration and anions on the performance of a Ni-H2 battery positive plate, advanced dependent pressure vessel nickel hydrogen spacecraft cell and battery design, electrolyte management considerations in modern nickel hydrogen and nickel cadmium cell and battery design, a novel unitized regenerative proton exchange membrane fuel cell, fuel cell systems for first lunar outpost - reactant storage options, the TMI regenerable solid oxide fuel cell, engineering development program of a closed aluminum-oxygen semi-cell system for an unmanned underwater vehicle, SPE OBOGS on-board oxygen generating system, hermetically sealed aluminum electrolytic capacitor, sol-gel technology and advanced electrochemical energy storage materials, development of electrochemical supercapacitors for EMA applications, and high energy density electrolytic capacitor.

  3. Electrochemical processing of solid waste

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    The investigation into electrolysis as a means of waste treatment and recycling on manned space missions is described. The electrochemical reactions of an artificial fecal waste mixture was examined. Waste electrolysis experiments were performed in a single compartment reactor, on platinum electrodes, to determine conditions likely to maximize the efficiency of oxidation of fecal waste material to CO2. The maximum current efficiencies for artificial fecal waste electrolysis to CO2 was found to be around 50 percent in the test apparatus. Experiments involving fecal waste oxidation on platinum indicates that electrodes with a higher overvoltage for oxygen evolution such as lead dioxide will give a larger effective potential range for organic oxidation reactions. An electrochemical packed column reactor was constructed with lead dioxide as electrode material. Preliminary experiments were performed using a packed-bed reactor and continuous flow techniques showing this system may be effective in complete oxidation of fecal material. The addition of redox mediator Ce(3+)/Ce(4+) enhances the oxidation process of biomass components. Scientific literature relevant to biomass and fecal waste electrolysis were reviewed.

  4. Electrochemical treatment of liquid wastes

    SciTech Connect

    Hobbs, D.T.

    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. Electrochemically assisted pyrolysis of hardwoods

    SciTech Connect

    Koch, V.R.

    1986-08-01

    This project explored the low-temperature, electrochemically assisted pyrolysis of lignocellulosic material to low-molecular-weight organic chemicals. Through the agency of low temperature AlCl{sub 3}-based molten salts, aspen hardwood flour was reacted in AlCl{sub 3}:NaCl, AlCl{sub 3}:NaCl:KCl, and AlCl{sub 3}:BPC (n-butylpyridinium chloride) media at temperatures from 30-220 C. A wide variety of water soluble products were formed comprising CO, CO{sub 2}, keto-alcohols and low molecular weight phenolic compounds as determined by GC and FTIR spectroscopy. The compounds represented about 32% by weight of the aspen wood flour. Owing to the narrow (2 volt) electrochemical window versus an Al reference electrode, neither the wood flour nor the reaction products manifested any electro-activity. Authentic samples of cellulose, hemicellulose, and Klason lignin were also subjected to low temperature pyrolysis. Only the hemicellulose reacted to give CO{sub 2} and keto-alcohols.

  6. Topics in electrochemical degradation of photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Mon, G. R.

    1984-01-01

    Electrochemical degradation of photovoltaic modules was examined. It is found that the extent of electrochemical damage is dependent on the integrated leakage current. The PV electrochemical degradation mechanisms in the two polarities are different: (1) degradation rates in the two polarities are of the same order of magnitude; (2) center tapped grounded arrays are a preferred system configuration to minimize electrochemical degradation. The use of thicker pottant layers and polymer substrate films to reduce equilibrium leakage current values is suggested. A metallized substrate layer, if used, should be isolated from the pottant and the frame by polyester layers, and EVA modules appear to be consistent with 30 year life allocation levels for electrochemical damage. Temperature acceleration factors are well behaved and moderately well understood; humidity acceleration factors vary radically with module construction and materials and require additional research.

  7. Electrochemical post-functionalization of conducting polymers.

    PubMed

    Inagi, Shinsuke; Fuchigami, Toshio

    2014-05-01

    This article summarizes recent progress in the post-functionalization of conjugated polymers by electrochemical methods. These electrochemical polymer reactions typically proceed via electrochemical doping of a conjugated polymer film, followed by chemical transformation. Examples include the quantitative oxidative fluorination of polyfluorenes and oxidative halogenation of polythiophenes, as well as the reductive hydrogenation of polyfluorenones. The degree of functionalization, otherwise known as the reaction ratio, can be controlled by varying the charge passed through the polymer, allowing the optoelectronic properties of the conjugated polymers to be tailored. Wireless bipolar electrodes with an in-plane potential distribution are also useful with regard to the electrochemical doping and reaction of conjugated polymers and allow the synthesis of films exhibiting composition gradients. Such bipolar electrochemistry can induce multiple reaction sites during electrochemical polymer reactions.

  8. Bussing Structure In An Electrochemical Cell

    DOEpatents

    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.

  9. Electrochemical hydrogenation of thiophene on SPE electrodes

    NASA Astrophysics Data System (ADS)

    Huang, Haiyan; Yuan, Penghui; Yu, Ying; Chung, Keng H.

    2017-01-01

    Electrochemical reduction desulfurization is a promising technology for petroleum refining which is environmental friendly, low cost and able to achieve a high degree of automation. Electrochemical hydrogenation of thiophene was performed in a three-electrode system which SPE electrode was the working electrode. The electrochemical desulfurization was studied by cyclic voltammetry and bulk electrolysis with coulometry (BEC) techniques. The results of cyclic voltammetry showed that the electrochemical hydrogenation reduction reaction occurred at -0.4V. The BEC results showed that the currents generated from thiophene hydrogenation reactions increased with temperature. According to Arrhenius equation, activation energy of thiophene electrolysis was calculated and lower activation energy value indicated it was diffusion controlled reaction. From the products of electrolytic reactions, the mechanisms of electrochemical hydrogenation of thiophene were proposed, consisting of two pathways: openingring followed by hydrogenation, and hydrogenation followed by ring opening.

  10. Nanotube Forests for Electrochemical Energy Storage from Electrostatic Assembly

    NASA Astrophysics Data System (ADS)

    Shao, Lin; Jang, Woo-Sik; Lutkenhaus, Jodie

    2011-03-01

    With increasing global energy consumption, efficient energy storage sytems are urgently needed. Currently, lithium-ion batteries are prevalent in many of these applications because of their established reliability and superior performance relative to older technologies; however, Li-ion batteries can be limited by mass transfer and safety concerns. Here, we present nanostructured polymer-based electrodes that potentially address these limitations. We apply layer-by-layer (LbL) assembly and nanotemplating to realize LbL-nanotube cathode arrays containing vanadium pentoxide and polyaniline. Both polyaniline and V2O5 store charge via doping/undoping and intercalation/deintercalation, respectively. The aim is to create high surface area electrodes that minimize the diffusion resistance of reactants, which could boost power density. The (LbL) growth profile was monitored using UV-Vis spectroscopy and profilometery. Electrochemical properties were characterized using cyclic voltammetery. Scanning electron microscopy images confirm that large areas of LbL nanotubes can be made. Future work will assess how nanostructured cathodes will behave electrochemically as nanotube aspect ratio is varied. NSF-CBET 0938842.

  11. Spatially resolved probing of electrochemical reactions via energy discovery platforms

    SciTech Connect

    Ding, Jilai; Strelcov, Evgheni; Kalinin, Sergei V.; Bassiri-Gharb, Nazanin

    2015-06-01

    The electrochemical reactivity of solid surfaces underpins functionality of a broad spectrum of materials and devices ranging from energy storage and conversion, to sensors and catalytic devices. The surface electrochemistry is, however, a complex process, controlled by the interplay of charge generation, field-controlled and diffusion-controlled transport. Here we explore the fundamental mechanisms of electrochemical reactivity on nanocrystalline ceria, using the synergy of nanofabricated devices and time-resolved Kelvin probe force microscopy (tr-KPFM), an approach we refer to as energy discovery platform. Through tr-KPFM, the surface potential mapping in both the space and time domains and current variation over time are obtained, enabling analysis of local ionic and electronic transport and their dynamic behavior on the 10 ms to 10 s scale. Based on their different responses in the time domain, conduction mechanisms can be separated and identified in a variety of environmental conditions, such as humidity and temperature. The theoretical modeling of ion transport through finite element method allows for creation of a minimal model consistent with observed phenomena, and establishing of the dynamic characteristics of the process, including mobility and diffusivity of charged species. Furthermore, the future potential of the energy discovery platforms is also discussed.

  12. Interferences in electrochemical hydride generation of hydrogen selenide

    NASA Astrophysics Data System (ADS)

    Bolea, E.; Laborda, F.; Belarra, M. A.; Castillo, J. R.

    2001-12-01

    Interferences from Cu(II), Zn(II), Pt(IV), As(III) and nitrate on electrochemical hydride generation of hydrogen selenide were studied using a tubular flow-through generator, flow injection sample introduction and quartz tube atomic absorption spectrometry. Comparison with conventional chemical generation using tetrahydroborate was also performed. Lead and reticulated vitreous carbon (RVC), both in particulate form, were used as cathode materials. Signal supressions up to 60-75%, depending on the cathode material, were obtained in the presence of up to 200 mg l-1 of nitrate due to the competitive reduction of the anion. Interference from As(III) was similar in electrochemical and chemical generation, being related to the quartz tube atomization process. Zinc did not interfere up to Se/Zn ratios 1:100, whereas copper and platinum showed suppression levels up to 50% for Se/interferent ratios 1:100. Total signal suppression was observed in presence of Se/Cu ratios 1:100 when RVC cathodes were used. No memory effects were observed in any case. Scanning electron microscopy and squared wave voltametry studies supported the interference mechanism based on the decomposition of the hydride on the dispersed particles of the reduced metal.

  13. Two-phase electrochemical lithiation in amorphous silicon.

    PubMed

    Wang, Jiang Wei; He, Yu; Fan, Feifei; Liu, Xiao Hua; Xia, Shuman; Liu, Yang; Harris, C Thomas; Li, Hong; Huang, Jian Yu; Mao, Scott X; Zhu, Ting

    2013-02-13

    Lithium-ion batteries have revolutionized portable electronics and will be a key to electrifying transport vehicles and delivering renewable electricity. Amorphous silicon (a-Si) is being intensively studied as a high-capacity anode material for next-generation lithium-ion batteries. Its lithiation has been widely thought to occur through a single-phase mechanism with gentle Li profiles, thus offering a significant potential for mitigating pulverization and capacity fade. Here, we discover a surprising two-phase process of electrochemical lithiation in a-Si by using in situ transmission electron microscopy. The lithiation occurs by the movement of a sharp phase boundary between the a-Si reactant and an amorphous Li(x)Si (a-Li(x)Si, x ~ 2.5) product. Such a striking amorphous-amorphous interface exists until the remaining a-Si is consumed. Then a second step of lithiation sets in without a visible interface, resulting in the final product of a-Li(x)Si (x ~ 3.75). We show that the two-phase lithiation can be the fundamental mechanism underpinning the anomalous morphological change of microfabricated a-Si electrodes, i.e., from a disk shape to a dome shape. Our results represent a significant step toward the understanding of the electrochemically driven reaction and degradation in amorphous materials, which is critical to the development of microstructurally stable electrodes for high-performance lithium-ion batteries.

  14. Kinetics of electrochemical boriding of low carbon steel

    NASA Astrophysics Data System (ADS)

    Kartal, G.; Eryilmaz, O. L.; Krumdick, G.; Erdemir, A.; Timur, S.

    2011-05-01

    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 2B 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.

  15. CO2 decomposition using electrochemical process in molten salts

    NASA Astrophysics Data System (ADS)

    Otake, Koya; Kinoshita, Hiroshi; Kikuchi, Tatsuya; Suzuki, Ryosuke O.

    2012-08-01

    The electrochemical decomposition of CO2 gas to carbon and oxygen gas in LiCl-Li2O and CaCl2-CaO molten salts was studied. This process consists of electrochemical reduction of Li2O and CaO, as well as the thermal reduction of CO2 gas by the respective metallic Li and Ca. Two kinds of ZrO2 solid electrolytes were tested as an oxygen ion conductor, and the electrolytes removed oxygen ions from the molten salts to the outside of the reactor. After electrolysis in both salts, the aggregations of nanometer-scale amorphous carbon and rod-like graphite crystals were observed by transmission electron microscopy. When 9.7 %CO2-Ar mixed gas was blown into LiCl-Li2O and CaCl2-CaO molten salts, the current efficiency was evaluated to be 89.7 % and 78.5 %, respectively, by the exhaust gas analysis and the supplied charge. When a solid electrolyte with higher ionic conductivity was used, the current and carbon production became larger. It was found that the rate determining step is the diffusion of oxygen ions into the ZrO2 solid electrolyte.

  16. Electrochemical synthesis of carbon nanodots directly from alcohols.

    PubMed

    Deng, Jianhui; Lu, Qiujun; Mi, Naxiu; Li, Haitao; Liu, Meiling; Xu, Mancai; Tan, Liang; Xie, Qingji; Zhang, Youyu; Yao, Shouzhuo

    2014-04-22

    Carbon nanodots (C-dots) show great potential as an important material for biochemical sensing, energy conversion, photocatalysis, and optoelectronics because of their water solubility, chemical inertness, low toxicity, and photo- and electronic properties. Numerous methods have been proposed for the preparation of C-dots. However, complex procedures and strong acid treatments are often required, and the as-prepared C-dots tend to be of low quality, and in particular, have a low efficiency for photoluminescence. Herein, a facile and general strategy involving the electrochemical carbonization of low-molecular-weight alcohols is proposed. As precursors, the alcohols transited into carbon-containing particles after electrochemical carbonization under basic conditions. The resultant C-dots exhibit excellent excitation- and size-dependent fluorescence without the need for complicated purification and passivation procedures. The sizes of the as-prepared C-dots can be adjusted by varying the applied potential. High-quality C-dots are prepared successfully from different small molecular alcohols, suggesting that this research provides a new, highly universal method for the preparation of fluorescent C-dots. In addition, luminescence microscopy of the C-dots is demonstrated in human cancer cells. The results indicate that the as-prepared C-dots have low toxicity and can be used in imaging applications.

  17. Electrochemical Atomic Layer Epitaxy of InAs

    NASA Astrophysics Data System (ADS)

    Maddox, Clinton B.; Happek, Uwe; Flowers, Billy H., Jr.; Vaidyanathan, Raman; Wade, Travis L.; Stickney, John L.

    1999-11-01

    We report on the electrosynthesis of InAs semiconductor films at room temperature using electrochemical atomic layer epitaxy. With this novel technique a semiconductor film can be formed layer by layer, via electrodeposition. An automated thin-layer electrochemical flow cell system is used to deposit InAs. A layer of In is first deposited on a gold cathode from a solution containing ions of In. Using the proper potential, only an atomic layer of material is formed. The solution is then exchanged for one containing As ions, and the second atomic layer (at a different, ion-specific potential) is deposited. These two steps establish a cycle producing a monolayer of the compound. The cycle can be repeated to produce semiconductor films consisting of thousands of layers. The quality of the obtained films is analyzed using x-ray diffraction, atomic force microscopy, Raman spectroscopy, and infrared spectroscopy probing the bandgap of the material. This work is supported in part by the National Science Foundation and the University of Georgia Research Foundation.

  18. Electrochemical fabrication and amperometric sensor application of graphene sheets

    NASA Astrophysics Data System (ADS)

    Öztürk, Ayşe; Alanyalıoğlu, Murat

    2016-07-01

    Graphene sheets have been fabricated by applying two-step electrochemical processes in two-electrode cell system containing 0.1 M sodium dodecyl sulfate (SDS). First step is intercalation of SDS into graphite anode electrode and this process has been applied at different intercalation potential values of 1, 3, 5, and 7 V. Second step includes exfoliation of SDS-intercalated graphite electrode in the same medium by acting as cathode. Stable graphene dispersions are obtained after these two electrochemical steps. Characterization of graphene sheets have been carried out using scanning electron microscopy, electron dispersive spectroscopy, fourier transform infrared spectroscopy, UV-Vis. absorption spectroscopy, X-ray diffraction, and cyclic voltammetry techniques. Graphene sheets have been modified onto glassy carbon electrode (GCE) by drop-casting of graphene dispersion. Graphene/GCE having a good electrocatalytic activity has been used for amperometric determination of nitrite in both standard laboratory and real samples. The oxidation current density was linearly proportional to the nitrite concentration in a range between 1 and 250 μM. The sensitivity of the sensor was calculated as 0.843 μAμM-1 cm-2 with a detection limit of 0.24 μM at a signal-to-noise ratio of 3.0.

  19. Analysis of electrochemical noise by the stochastic process detector method

    SciTech Connect

    Roberge, P.R. . Dept. of Chemistry and Chemical Engineering)

    1994-07-01

    Electrochemical noise (EN) generated during the corrosion of metal specimens can be analyzed for its stochastic nature. Voltage fluctuations observed during the exposure of commercial aluminum (Al) sheet material were analyzed using a new technique based on randomness of these fluctuations. The stochastic process detector (SPD) technique was found to be very sensitive to the presence of deterministic features that are sometimes present in noise records. Results obtained with three orthogonal faces of Aluminum Association (AA) 7075-T6 Al alloy (UNS A97075) exposed to a saline solution were compared to electrochemical impedance spectroscopy (EIS) measurements and micrographs of exposed specimens. Some fundamental characteristics of voltage fluctuations revealed by SPD appeared to be related directly to the degree of localized corrosion in progress on the metal surfaces. The noise fluctuations' voltage rise times (RT) seemed to be related directly to the propensity of the AA 7075-T6 alloy tested to suffer from localized forms of corrosion visible under optical microscopy (OM). These findings agreed with variations observed in the constant-phase element (CPE) exponents, as calculated from EIS measurements, which also have been related to the degree of localized attack on corroding specimens.

  20. Electrochemical and Dry Sand Impact Erosion Studies on Carbon Steel

    PubMed Central

    Naz, M. Y.; Ismail, N. I.; Sulaiman, S. A.; Shukrullah, S.

    2015-01-01

    This study investigated the dry and aqueous erosion of mild steel using electrochemical and dry sand impact techniques. In dry sand impact experiments, mild steel was eroded with 45 μm and 150 μm sand particles. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and micro-hardness techniques were used to elaborate the surface morphology of the eroded samples. The results revealed significant change in morphology of the eroded samples. In-depth analysis showed that although the metal erosion due to larger particles was significantly higher, the fines also notably damaged the metal surface. The surface damages were appreciably reduced with decrease in impact angle of the accelerated particles. The maximum damages were observed at an impact angle of 90°. The hardness of the samples treated with 45 μm and 150 μm sand remained in the range of 88.34 to 102.31 VHN and 87.7 to 97.55 VHN, respectively. In electrochemical experiments, a triple electrode probe was added into the metal treatment process. The linear polarization resistance (LPR) measurements were performed in slurries having 5% (by weight) of sand particles. LPR of the samples treated with 45 μm and 150 μm sand slurries was calculated about 949 Ω.cm2 and 809 Ω.cm2, respectively. PMID:26561231

  1. Electrochemical dynamics of nanoscale metallic inclusions in dielectrics.

    PubMed

    Yang, Yuchao; Gao, Peng; Li, Linze; Pan, Xiaoqing; Tappertzhofen, Stefan; Choi, ShinHyun; Waser, Rainer; Valov, Ilia; Lu, Wei D

    2014-06-23

    Nanoscale metal inclusions in or on solid-state dielectrics are an integral part of modern electrocatalysis, optoelectronics, capacitors, metamaterials and memory devices. The properties of these composite systems strongly depend on the size, dispersion of the inclusions and their chemical stability, and are usually considered constant. Here we demonstrate that nanoscale inclusions (for example, clusters) in dielectrics dynamically change their shape, size and position upon applied electric field. Through systematic in situ transmission electron microscopy studies, we show that fundamental electrochemical processes can lead to universally observed nucleation and growth of metal clusters, even for inert metals like platinum. The clusters exhibit diverse dynamic behaviours governed by kinetic factors including ion mobility and redox rates, leading to different filament growth modes and structures in memristive devices. These findings reveal the microscopic origin behind resistive switching, and also provide general guidance for the design of novel devices involving electronics and ionics.

  2. Rapid prototyping of electrochemical lateral flow devices: stencilled electrodes.

    PubMed

    Aller Pellitero, Miguel; Kitsara, Maria; Eibensteiner, Friedrich; del Campo, F Javier

    2016-04-21

    A straightforward and very cost effective method is proposed to prototype electrodes using pressure sensitive adhesives (PSA) and a simple cutting technique. Two cutting methods, namely blade cutting and CO2 laser ablation, are compared and their respective merits are discussed. The proposed method consists of turning the protective liner on the adhesive into a stencil to apply screen-printing pastes. After the electrodes have been printed, the liner is removed and the PSA can be used as a backing material for standard lateral flow membranes. We present the fabrication of band electrodes down to 250 μm wide, and their characterization using microscopy techniques and cyclic voltammetry. The prototyping approach presented here facilitates the development of new electrochemical devices even if very limited fabrication resources are available. Here we demonstrate the fabrication of a simple lateral-flow device capable of determining glucose in blood. The prototyping approach presented here is highly suitable for the development of novel electroanalytical tools.

  3. Electrochemical Evaluation of Pyrite Films Prepared by Plasma Spraying

    SciTech Connect

    Guidotti, R.A.; Reinhardt, F.W.

    1998-10-30

    Thermally activated batteries use electrodes that are typically fabricated by cold pressing of powder. In the LiSi/FeS2 system, natural (mineral) pyrite is used for the cathode. In an effort to increase the energy density and specific energy of these batteries, flame and plasma spraying to form thin films of pyrite cathodes were evaluated. The films were deposited on a 304 stainless steel substrate (current collector) and were characterized by scanning electron microscopy and x-ray dlfllaction. The films were electrochemically tested in single cells at 5000C and the petiormance compared to that of standard cells made with cold-pressed powders. The best results were obtained with material deposited by de-arc plasma spraying with a proprietq additive to suppress thermal decomposion of the pyrite.

  4. Synthesis and Electrochemical Properties of Nano-VO2 (B).

    PubMed

    Yang, Yun; Lu, Yong; Wang, Wei; Feng, Chuanqi; Yang, Shuijin

    2016-03-01

    The nano-VO2 (B) has been self-assembly synthesized by hydrothermal method using different templates, which may give them some interesting properties. The as-prepared samples were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties of the samples were investigated. The results show that the hexadecyltrimethyl ammonium bromide (CTAB) (soft template) was used to obtain the VO2 (B1) nanobelts. The flake graphite (hard template) was taken to get the VO2 (B2) nanosheets. The VO2 (B1) nanobelts have higher initial capacity to compare with VO2 (B2). But the VO2 (B2) nanosheets showed better cycling performance than that of VO2 (B1) nanobelts. The nano VO2 (B2) is a promising anode material for lithium ion battery application.

  5. Enhanced photocatalytic activity of electrochemically synthesized aluminum oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Pathania, Deepak; Katwal, Rishu; Kaur, Harpreet

    2016-03-01

    In this study, aluminum oxide (Al2O3) nanoparticles (NPs) were synthesized via an electrochemical method. The effects of reaction parameters such as supporting electrolytes, solvent, current and electrolysis time on the shape and size of the resulting NPs were investigated. The Al2O3 NPs were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, thermogravimetric analysis/differential thermal analysis, energy-dispersive X-ray analysis, and ultraviolet-visible spectroscopy. Moreover, the Al2O3 NPs were explored for photocatalytic degradation of malachite green (MG) dye under sunlight irradiation via two processes: adsorption followed by photocatalysis; coupled adsorption and photocatalysis. The coupled process exhibited a higher photodegradation efficiency (45%) compared to adsorption followed by photocatalysis (32%). The obtained kinetic data was well fitted using a pseudo-first-order model for MG degradation.

  6. Electrochemical reactivity and proton transport mechanisms in nanostructured ceria

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  7. Electrodeposition of polymer electrolyte in nanostructured electrodes for enhanced electrochemical performance of thin-film Li-ion microbatteries

    NASA Astrophysics Data System (ADS)

    Salian, Girish D.; Lebouin, Chrystelle; Demoulin, A.; Lepihin, M. S.; Maria, S.; Galeyeva, A. K.; Kurbatov, A. P.; Djenizian, Thierry

    2017-02-01

    We report that electrodeposition of polymer electrolyte in nanostructured electrodes has a strong influence on the electrochemical properties of thin-film Li-ion microbatteries. Electropolymerization of PMMA-PEG (polymethyl methacrylate-polyethylene glycol) was carried out on both the anode (self-supported titania nanotubes) and the cathode (porous LiNi0.5Mn1.5O4) by cyclic voltammetry and the resulting electrode-electrolyte interface was examined by scanning electron microscopy. The electrochemical characterizations performed by galvanostatic experiments reveal that the capacity values obtained at different C-rates are doubled when the electrodes are completely filled by the polymer electrolyte.

  8. Electrochemical Deposition of Si-Ca/P on Nanotube Formed Beta Ti Alloy by Cyclic Voltammetry Method.

    PubMed

    Jeong, Yong-Hoon; Choe, Han-Cheol

    2015-08-01

    The purpose of this study was to investigate electrochemical deposition of Si-Ca/P on nanotube formed Ti-35Nb-10Zr alloy by cyclic voltammetry method. Electrochemical deposition of Si substituted Ca/P was performed by pulsing the applied potential on nanotube formed surface. The surface characteristics were observed by field-emission scanning electron microscopy, X-ray diffractometer, and potentiodynamic polarization test. The phase structure and surface morphologies of Si-Ca/P deposition were affected by deposition cycles. From the anodic polarization test, nanotube formed surface at 20 V showed the high corrosion resistance with lower value of Icorr, I300, and Ipass.

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

    PubMed

    Stamatin, Serban N; Speder, Jozsef; Dhiman, Rajnish; Arenz, Matthias; Skou, Eivind M

    2015-03-25

    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 different potential cycle aging tests were used in order to accelerate the support corrosion, simulating start-up/shutdown and load cycling. On the basis of the results, we draw two main conclusions. First, platinized silicon carbide exhibits improved electrochemical stability over platinized active carbons. Second, silicon carbide undergoes at least mild oxidation if not even silicon leaching.

  10. Preliminary study of structural changes in Li2MnSiO4 cathode material during electrochemical reaction

    NASA Astrophysics Data System (ADS)

    Świętosławski, Michał; Molenda, Marcin; Gajewska, Marta

    2016-06-01

    In this paper, we present exsitu observations of a structure of particular Li2MnSiO4 grains at different states of charge (SOC). The goal of these studies is structural analysis of Li2MnSiO4 cathode material for Li-ion batteries at different stages of electrochemical reaction using transmission electron microscopy. Performed analysis suggests that amorphization process of Li2MnSiO4 is not directly connected with lithium ions deintercalation but with additional electrochemical reactions running in the working cell.

  11. Electrochemical and electron microscopic characterization of Super-P based cathodes for Li-O2 batteries.

    PubMed

    Marinaro, Mario; Eswara Moorthy, Santhana K; Bernhard, Jörg; Jörissen, Ludwig; Wohlfahrt-Mehrens, Margret; Kaiser, Ute

    2013-01-01

    Aprotic rechargeable Li-O2 batteries are currently receiving considerable interest because they can possibly offer significantly higher energy densities than conventional Li-ion batteries. The electrochemical behavior of Li-O2 batteries containing bis(trifluoromethane)sulfonimide lithium salt (LiTFSI)/tetraglyme electrolyte were investigated by galvanostatic cycling and electrochemical impedance spectroscopy measurements. Ex-situ X-ray diffraction and scanning electron microscopy were used to evaluate the formation/dissolution of Li2O2 particles at the cathode side during the operation of Li-O2 cells.

  12. Exploration of two-enzyme coupled catalysis system using scanning electrochemical microscopy.

    PubMed

    Wu, Zeng-Qiang; Jia, Wen-Zhi; Wang, Kang; Xu, Jing-Juan; Chen, Hong-Yuan; Xia, Xing-Hua

    2012-12-18

    In biological metabolism, a given metabolic process usually occurs via a group of enzymes working together in sequential pathways. To explore the metabolism mechanism requires the understanding of the multienzyme coupled catalysis systems. In this paper, an approach has been proposed to study the kinetics of a two-enzyme coupled reaction using SECM combining numerical simulations. Acetylcholine esterase and choline oxidase are immobilized on cysteamine self-assembled monolayers on tip and substrate gold electrodes of SECM via electrostatic interactions, respectively. The reaction kinetics of this two-enzyme coupled system upon various separation distance precisely regulated by SECM are measured. An overall apparent Michaelis-Menten constant of this enzyme cascade is thus measured as 2.97 mM at an optimal tip-substrate gap distance of 18 μm. Then, a kinetic model of this enzyme cascade is established for evaluating the kinetic parameters of individual enzyme by using the finite element method. The simulated results demonstrate the choline oxidase catalytic reaction is the rate determining step of this enzyme cascade. The Michaelis-Menten constant of acetylcholine esterase is evaluated as 1.8 mM. This study offers a promising approach to exploring mechanism of other two-enzyme coupled reactions in biological system and would promote the development of biosensors and enzyme-based logic systems.

  13. Impedance Spectroscopic Investigation of Proton Conductivity in Nafion Using Transient Electrochemical Atomic Force Microscopy (AFM)

    PubMed Central

    Hink, Steffen; Wagner, Norbert; Bessler, Wolfgang G.; Roduner, Emil

    2012-01-01

    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 0.2–1000 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. PMID:24958175

  14. Vacuum-Deposited Porphyrin Protective Films on Graphite: Electrochemical Atomic Force Microscopy Investigation during Anion Intercalation.

    PubMed

    Yivlialin, Rossella; Bussetti, Gianlorenzo; Penconi, Marta; Bossi, Alberto; Ciccacci, Franco; Finazzi, Marco; Duò, Lamberto

    2017-02-01

    The development of graphene products promotes a renewed interest toward the use of graphite in addition to the historical one for its proven viability as battery electrode. However, when exposed to harsh conditions, the graphite surface ages in ways that still need to be fully characterized. In applications to batteries, to optimize the electrode performances in acid solutions, different surface functionalizations have been studied. Among them, aromatic molecules have been recently proposed. In this communication, we report on the protective effect exerted by a physical-vapor-deposited porphyrin layer. Metal-free tetra-phenyl-porphyrins were deposited on a highly oriented pyrolytic graphite crystal to study the modifications that occur during anion intercalation in graphite. The graphite electrode was plunged in an electrolyte solution of 1 M sulfuric acid and subjected to cyclic voltammetry. The results indicate that blister formation, the characteristic swelling of graphite surface induced by anion intercalation, is significantly perturbed by the porphyrin overlayer; the process is inhibited in those areas where the protective porphyrin film is present. We ascribe the inhibition of the anion intercalation to the protective porphyrin wetting layer.

  15. Electrochemical spectroscopy of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Hwang, Jungseek

    Conjugated polymers become conductors when they are doped (oxidized or reduced). The initial work was done on conducting polymers by three Nobel laureates (A. J. Heeger, H. Shirakawa, and A. G. MacDiarmid) in 1977. They discovered an increase by nearly 10 orders of magnitude in the electrical conductivity of polyacetylene when it was doped with iodine or other acceptors. Conjugated polymers have been studied intensively since that time because of their high conductivity, reversible doping and low-dimensional geometry. Doping causes electronic structure changes which have numerous potential applications. We have studied three thiophene derivative polymers: poly (3,4-ethylenedioxy-thiophene) (PEDOT), poly (3,4-propylenedioxythiophene) (PProDOT), and poly (3,4-dimethylpropylenedioxythiophene) (PProDOTMe2). Two types of samples were used for this study. The first was a thin polymer film on an indium tin oxide (ITO) coated glass slide. The polymer film was deposited on a metallic ITO surface by an electrochemical method. We measured reflectance and transmittance of the sample. The data were analyzed by modeling all layers of this multi-layer thin film structure, using the Drude-Lorentz model for each layer. We calculated the optical constants from the modeling results and obtained information on the electronic structure of the neutral and doped polymers. Conjugated polymers can be reversibly doped in an electrochemical cell. The doping causes optical absorption bands to move from one optical frequency to another frequency. To study this behavior, we prepared another type of sample. First, a thin polymer film was deposited on a gold-coated Mylar film by the same electrochemical method. Then, we built electrochromic cells with an infrared transparent window, using the polymer films on the gold/Mylar strips as electrodes. We connected the cell to an electrical supply. As we change the cell voltage (potential difference between the two electrodes), we can change the doping

  16. Structured line illumination Raman microscopy

    PubMed Central

    Watanabe, Kozue; Palonpon, Almar F.; Smith, Nicholas I.; Chiu, Liang-da; Kasai, Atsushi; Hashimoto, Hitoshi; Kawata, Satoshi; Fujita, Katsumasa

    2015-01-01

    In the last couple of decades, the spatial resolution in optical microscopy has increased to unprecedented levels by exploiting the fluorescence properties of the probe. At about the same time, Raman imaging techniques have emerged as a way to image inherent chemical information in a sample without using fluorescent probes. However, in many applications, the achievable resolution is limited to about half the wavelength of excitation light. Here we report the use of structured illumination to increase the spatial resolution of label-free spontaneous Raman microscopy, generating highly detailed spatial contrast from the ensemble of molecular information in the sample. Using structured line illumination in slit-scanning Raman microscopy, we demonstrate a marked improvement in spatial resolution and show the applicability to a range of samples, including both biological and inorganic chemical component mapping. This technique is expected to contribute towards greater understanding of chemical component distributions in organic and inorganic materials. PMID:26626144

  17. Computational 'microscopy' of cellular membranes.

    PubMed

    Ingólfsson, Helgi I; Arnarez, Clément; Periole, Xavier; Marrink, Siewert J

    2016-01-15

    Computational 'microscopy' refers to the use of computational resources to simulate the dynamics of a molecular system. Tuned to cell membranes, this computational 'microscopy' technique is able to capture the interplay between lipids and proteins at a spatio-temporal resolution that is unmatched by other methods. Recent advances allow us to zoom out from individual atoms and molecules to supramolecular complexes and subcellular compartments that contain tens of millions of particles, and to capture the complexity of the crowded environment of real cell membranes. This Commentary gives an overview of the main concepts of computational 'microscopy' and describes the state-of-the-art methods used to model cell membrane processes. We illustrate the power of computational modelling approaches by providing a few in-depth examples of large-scale simulations that move up from molecular descriptions into the subcellular arena. We end with an outlook towards modelling a complete cell in silico.

  18. Correlative microscopy of detergent granules.

    PubMed

    van Dalen, G; Nootenboom, P; Heussen, P C M

    2011-03-01

    The microstructure of detergent products for textile cleaning determines to a large extent the physical properties of these products. Correlative microscopy was used to reveal the microstructure by reconciling images obtained by scanning electron microscopy with energy dispersive X-ray analysis, X-ray microtomography and Fourier transform infrared microscopy. These techniques were applied on the same location of a subsample of a spray-dried detergent base powder embedded in polyacrylate. In this way, the three-dimensional internal and external structure of detergent granules could be investigated from milli to nano scale with detailed spatial information about the components present. This will generate knowledge how to design optimal microstructures for laundry products to obtain product properties demanded by the market. This method is also very useful for other powder systems used in a large variety of industries (e.g. for pharmaceutical, food, ceramic and metal industries).

  19. Band Excitation in Scanning Probe Microscopy: Recognition and Functional Imaging

    NASA Astrophysics Data System (ADS)

    Jesse, S.; Vasudevan, R. K.; Collins, L.; Strelcov, E.; Okatan, M. B.; Belianinov, A.; Baddorf, A. P.; Proksch, R.; Kalinin, S. V.

    2014-04-01

    Field confinement at the junction between a biased scanning probe microscope's tip and solid surface enables local probing of various bias-induced transformations, such as polarization switching, ionic motion, and electrochemical reactions. The nanoscale size of the biased region, smaller or comparable to that of features such as grain boundaries and dislocations, potentially allows for the study of kinetics and thermodynamics at the level of a single defect. In contrast to classical statistically averaged approaches, this approach allows one to link structure to functionality and deterministically decipher associated mesoscopic and atomistic mechanisms. Furthermore, responses measured as a function of frequency and bias can serve as a fingerprint of local material functionality, allowing for local recognition imaging of inorganic and biological systems. This article reviews current progress in multidimensional scanning probe microscopy techniques based on band excitation time and voltage spectroscopies, including discussions on data acquisition, dimensionality reduction, and visualization, along with future challenges and opportunities for the field.

  20. Advanced analytical electron microscopy for alkali-ion batteries

    DOE PAGES

    Qian, Danna; Ma, Cheng; Meng, Ying Shirley; ...

    2015-01-01

    Lithium-ion batteries are a leading candidate for electric vehicle and smart grid applications. However, further optimizations of the energy/power density, coulombic efficiency and cycle life are still needed, and this requires a thorough understanding of the dynamic evolution of each component and their synergistic behaviors during battery operation. With the capability of resolving the structure and chemistry at an atomic resolution, advanced analytical transmission electron microscopy (AEM) is an ideal technique for this task. The present review paper focuses on recent contributions of this important technique to the fundamental understanding of the electrochemical processes of battery materials. A detailed reviewmore » of both static (ex situ) and real-time (in situ) studies will be given, and issues that still need to be addressed will be discussed.« less

  1. Advanced analytical electron microscopy for alkali-ion batteries

    SciTech Connect

    Qian, Danna; Ma, Cheng; Meng, Ying Shirley; More, Karren; Chi, Miaofang

    2015-01-01

    Lithium-ion batteries are a leading candidate for electric vehicle and smart grid applications. However, further optimizations of the energy/power density, coulombic efficiency and cycle life are still needed, and this requires a thorough understanding of the dynamic evolution of each component and their synergistic behaviors during battery operation. With the capability of resolving the structure and chemistry at an atomic resolution, advanced analytical transmission electron microscopy (AEM) is an ideal technique for this task. The present review paper focuses on recent contributions of this important technique to the fundamental understanding of the electrochemical processes of battery materials. A detailed review of both static (ex situ) and real-time (in situ) studies will be given, and issues that still need to be addressed will be discussed.

  2. Confocal microscopy and exfoliative cytology

    PubMed Central

    Reddy, Shyam Prasad; Ramani, Pratibha; Nainani, Purshotam

    2013-01-01

    Context: Early detection of potentially malignant lesions and invasive squamous-cell carcinoma in the oral cavity could be greatly improved through techniques that permit visualization of subtle cellular changes indicative of the neoplastic transformation process. One such technique is confocal microscopy. Combining rapidity with reliability, an innovative idea has been put forward using confocal microscope in exfoliative cytology. Aims: The main objective of this study was to assess confocal microscopy for cytological diagnosis and the results were compared with that of the standard PAP stain. Settings and Design: Confocal microscope, acridine orange (AO) stain, PAP (Papanicolaou) stain. The study was designed to assess confocal microscopy for cytological diagnosis. In the process, smears of patients with (clinically diagnosed and/or suspected) oral squamous cell carcinoma as well as those of controls (normal people) were stained with acridine orange and observed under confocal microscope. The results were compared with those of the standard PAP method. Materials and Methods: Samples of buccal mucosa smears from normal patients and squamous cell carcinoma patients were made, fixed in 100% alcohol, followed by AO staining. The corresponding set of smears was stained with PAP stain using rapid PAP stain kit. The results obtained were compared with those obtained with AO confocal microscopy. Results: The study had shown nuclear changes (malignant cells) in the smears of squamous cell carcinoma patients as increased intensity of fluorescence of the nucleus, when observed under confocal microscope. Acridine orange confocal microscopy showed good amount of sensitivity and specificity (93%) in identifying malignant cells in exfoliative cytological smears. Conclusion: Confocal microscopy was found to have good sensitivity in the identification of cancer (malignant) cells in exfoliative cytology, at par with the PAP method. The rapidity of processing and screening a

  3. DHMI: dynamic holographic microscopy interface

    NASA Astrophysics Data System (ADS)

    He, Xuefei; Zheng, Yujie; Lee, Woei Ming

    2016-12-01

    Digital holographic microscopy (DHM) is a powerful in-vitro biological imaging tool. In this paper, we report a fully automated off-axis digital holographic microscopy system completed with a graphical user interface in the Matlab environment. The interface primarily includes Fourier domain processing, phase reconstruction, aberration compensation and autofocusing. A variety of imaging operations such as region of interest selection, de-noising mode (filtering and averaging), low frame rate imaging for immediate reconstruction and high frame rate imaging routine ( 27 fps) are implemented to facilitate ease of use.

  4. The future of electron microscopy

    SciTech Connect

    Zhu, Yimei; Durr, Hermann

    2015-04-01

    Seeing is believing. So goes the old adage and seen evidence is undoubtedly satisfying because it can be interpreted easily, though not always correctly. For centuries, humans have developed such instruments as telescopes that observe the heavens and microscopes that reveal bacteria and viruses. The 2014 Nobel Prize in Chemistry was awarded to Eric Betzig, Stefan Hell, and William Moerner for their foundational work on superresolution fluorescence microscopy in which they overcame the Abbe diffraction limit for the resolving power of conventional light microscopes. (See Physics Today, December 2014, page 18.) That breakthrough enabled discoveries in biological research and testifies to the importance of modern microscopy.

  5. The future of electron microscopy

    DOE PAGES

    Zhu, Yimei; Durr, Hermann

    2015-04-01

    Seeing is believing. So goes the old adage and seen evidence is undoubtedly satisfying because it can be interpreted easily, though not always correctly. For centuries, humans have developed such instruments as telescopes that observe the heavens and microscopes that reveal bacteria and viruses. The 2014 Nobel Prize in Chemistry was awarded to Eric Betzig, Stefan Hell, and William Moerner for their foundational work on superresolution fluorescence microscopy in which they overcame the Abbe diffraction limit for the resolving power of conventional light microscopes. (See Physics Today, December 2014, page 18.) That breakthrough enabled discoveries in biological research and testifiesmore » to the importance of modern microscopy.« less

  6. The origin of electrochemical nomenclature.

    PubMed

    Giddens, W R

    2001-09-01

    This article is about the origin and development of certain words that are important in the vocabulary of all physicians and scientists. The words that make up the electrochemical nomenclature were created in 1833 by Michael Faraday and several of his friends. Terms such as electrolyte, ion, and electrode were invented in a fashion that ignored theory but fitted the experimental facts of the laboratory. This nomenclature, derived from Greek, was so accurate and functional that is has been completely incorporated into modern chemistry, a fact that seems remarkable since the structure of the atom was completely unknown at the time. To fully develop the etymology of these words, the life of Faraday is summarized and the deliberations of the men involved are reviewed.

  7. Composite Electrodes for Electrochemical Supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Jun; Yang, Quan Min; Zhitomirsky, Igor

    2010-03-01

    Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4-6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT) into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with total mass loading of 7-15 mg cm-2, showed a capacitive behavior in 0.5-M Na2SO4 solutions. The decrease in stirring time during precipitation of the nanofibers resulted in reduced agglomeration and higher specific capacitance (SC). The highest SC of 185 F g-1 was obtained at a scan rate of 2 mV s-1 for mass loading of 7 mg cm-2. The SC decreased with increasing scan rate and increasing electrode mass.

  8. Electrochemical formation of field emitters

    DOEpatents

    Bernhardt, A.F.

    1999-03-16

    Electrochemical formation of field emitters, particularly useful in the fabrication of flat panel displays is disclosed. The fabrication involves field emitting points in a gated field emitter structure. Metal field emitters are formed by electroplating and the shape of the formed emitter is controlled by the potential imposed on the gate as well as on a separate counter electrode. This allows sharp emitters to be formed in a more inexpensive and manufacturable process than vacuum deposition processes used at present. The fabrication process involves etching of the gate metal and the dielectric layer down to the resistor layer, and then electroplating the etched area and forming an electroplated emitter point in the etched area. 12 figs.

  9. Cathode for an electrochemical cell

    DOEpatents

    Bates, John B.; Dudney, Nancy J.; Gruzalski, Greg R.; Luck, Christopher F.

    2001-01-01

    Described is a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode. Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between -15.degree. C. and 150.degree. C.

  10. Electrolyte for an electrochemical cell

    DOEpatents

    Bates, J.B.; Dudney, N.J.

    1997-01-28

    Described is a thin-film battery, especially a thin-film microbattery, and a method for making the same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte amorphous lithium phosphorus oxynitride which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between {minus}15 C and 150 C. 9 figs.

  11. Electrolyte for an electrochemical cell

    DOEpatents

    Bates, John B.; Dudney, Nancy J.

    1997-01-01

    Described is a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte amorphous lithium phosphorus oxynitride which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between -15.degree. C. and 150.degree. C.

  12. Electrochemical studies of corrosion inhibitors

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1990-01-01

    The effect of single salts, as well as multicomponent mixtures, on corrosion inhibition was studied for type 1010 steel; for 5052, 1100, and 2219-T87 aluminum alloys; and for copper. Molybdate-containing inhibitors exhibit an immediate, positive effect for steel corrosion, but an incubation period may be required for aluminum before the effect of a given inhibitor can be determined. The absence of oxygen was found to provide a positive effect (smaller corrosion rate) for steel and copper, but a negative effect for aluminum. This is attributed to the two possible mechanisms by which aluminum can oxidize. Corrosion inhibition is generally similar for oxygen-rich and oxygen-free environments. The results show that the electrochemical method is an effective means of screening inhibitors for the corrosion of single metals, with caution to be exercised in the case of aluminum.

  13. Multichannel electrochemical microbial detection unit

    NASA Technical Reports Server (NTRS)

    Wilkins, J. R.; Young, R. N.; Boykin, E. H.

    1978-01-01

    The paper describes the design and capabilities of a compact multichannel electrochemical unit devised to detect and automatically indicate detection time length of bacteria. By connecting this unit to a strip-chart recorder, a permanent record is obtained of the end points and growth curves for each of eight channels. The experimental setup utilizing the multichannel unit consists of a test tube (25 by 150 mm) containing a combination redox electrode plus 18 ml of lauryl tryptose broth and positioned in a 35-C water bath. Leads from the electrodes are connected to the multichannel unit, which in turn is connected to a strip-chart recorder. After addition of 2.0 ml of inoculum to the test tubes, depression of the push-button starter activates the electronics, timer, and indicator light for each channel. The multichannel unit is employed to test tenfold dilutions of various members of the Enterobacteriaceae group, and a typical dose-response curve is presented.

  14. Gravitational effects on electrochemical batteries

    NASA Technical Reports Server (NTRS)

    Meredith, R. E.; Juvinall, G. L.; Uchiyama, A. A.

    1972-01-01

    The existing work on gravitational effects on electrochemical batteries is summarized, certain conclusions are drawn, and recommendations are made for future activities in this field. The effects of sustained high-G environments on cycle silver-zinc and nickel-cadmium cells have been evaluated over four complete cycles in the region of 10 to 75 G. Although no effects on high current discharge performances or on ampere-hour capacity were noted, severe zinc migration and sloughing of active material from the zinc electrode were observed. This latter effect constitutes real damage, and over a long period of time would result in loss of capacity. It is recommended that a zero-G battery experiment be implemented. Both an orbiting satellite and a sounding rocket approach are being considered.

  15. Optical microscopy versus scanning electron microscopy in urolithiasis.

    PubMed

    Marickar, Y M Fazil; Lekshmi, P R; Varma, Luxmi; Koshy, Peter

    2009-10-01

    Stone analysis is incompletely done in many clinical centers. Identification of the stone component is essential for deciding future prophylaxis. X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy (SEM) still remains a distant dream for routine hospital work. It is in this context that optical microscopy is suggested as an alternate procedure. The objective of this article was to assess the utility of an optical microscope which gives magnification of up to 40x and gives clear picture of the surface of the stones. In order to authenticate the morphological analysis of urinary stones, SEM and elemental distribution analysis were performed. A total of 250 urinary stones of different compositions were collected from stone clinic, photographed, observed under an optical microscope, and optical photographs were taken at different angles. Twenty-five representative samples among these were gold sputtered to make them conductive and were fed into the SEM machine. Photographs of the samples were taken at different angles at magnifications up to 4,000. Elemental distribution analysis (EDAX) was done to confirm the composition. The observations of the two studies were compared. The different appearances of the stones under optical illuminated microscopy were mostly standardized appearances, namely bosselations of pure whewellite, spiculations of weddellite, bright yellow colored appearance of uric acid, and dirty white amorphous appearance of phosphates. SEM and EDAX gave clearer pictures and gave added confirmation of the stone composition. From the references thus obtained, it was possible to confirm the composition by studying the optical microscopic pictures. Higher magnification capacity of the SEM and the EDAX patterns are useful to give reference support for performing optical microscopy work. After standardization, routine analysis can be performed with optical microscopy. The advantage of the optical microscope is that, it

  16. Mediated electrochemical hazardous waste destruction

    SciTech Connect

    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{sup 2+} or Ce{sup +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.

  17. Electrochemical Measurement of Atmospheric Corrosion

    NASA Technical Reports Server (NTRS)

    DeArmond, Anna H.; Davis, Dennis D.; Beeson, Harold D.

    1999-01-01

    Corrosion of Shuttle thruster components in atmospheres containing high concentrations of nitrogen tetroxide (NTO) and water is an important issue in ground operations of bipropellant systems in humid locations. Measurements of the corrosivities of NTO-containing atmospheres and the responses of different materials to these atmospheres have been accomplished using an electrochemical sensor. The sensor is composed of alternating aluminum/titanium strips separated by thin insulating layers. Under high humidity conditions a thin film of water covers the surface of the sensor. Added NTO vapor reacts with the water film to form a conductive medium and establishes a galvanic cell. The current from this cell can be integrated with respect to time and related to the corrosion activity. The surface layer formed from humid air/NTO reacts in the same way as an aqueous solution of nitric acid. Nitric acid is generally considered an important agent in NTO corrosion situations. The aluminum/titanium sensor is unresponsive to dry air, responds slightly to humid air (> 75% RH), and responds strongly to the combination of humid air and NTO. The sensor response is a power function (n = 2) of the NTO concentration. The sensor does not respond to NTO in dry air. The response of other materials in this type of sensor is related to position of the material in a galvanic series in aqueous nitric acid. The concept and operation of this electrochemical corrosion measurement is being applied to other corrosive atmospheric contaminants such as hydrogen chloride, hydrogen fluoride, sulfur dioxide, and acidic aerosols.

  18. Electrochemical studies at high pressure

    SciTech Connect

    Cruanes, M.T.

    1993-01-01

    This research has dealt with the development and application of a methodology that permits electrochemical measurements at high pressure. The initial efforts focused on the design and construction of an electrochemical cell functional at hydrostatic pressures as high as 10 kbar. This cell was equipped with an Ag/AgCl/KCl (0.1M) reference electrode which provides reliable control of the potential at all pressures. The potential of this reference electrode can be considered to be constant with pressure. Measurements of formal potentials (E[degrees][prime]) of several transition-metal complexes vs the Ag/AgCl electrode rendered volumes of reactions whose magnitudes support the prediction of the negligible pressure dependence of the reference electrode. The main systems that have been investigated at high pressure are surface-modified electrodes. The author studied the effect of compression on the dynamics of charge transport in quaternized poly(4-vinylpyridine) (QPVP) films placed on gold electrodes, loaded with potassium ferricyanide, and equilibrated in potassium nitrate. Pressure accomplished the continuous change in the structure of the polymer network. This change causes a pronounced restriction in the propagation of charge and in the motion of mass. This high-pressure methodology has also allowed the spatial characterization of electron transfer events taking place between a gold electrode and ferrocene molecules covalently attached to the end of 1-undodecanethiol chains self-assembled on the electrode surface. The volumes of reaction and activation for the oxidation process are both positive, indicating that a volume expansion is associated with the formation of ferricinium. A model is proposed in which the creation of a vacancy in the self-assembled monolayer, for the accommodation of the ferricinium ion or a charge-compensating anion, is coupled with the electron transfer step.

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

    NASA Astrophysics Data System (ADS)

    Izquierdo, Javier; Bolat, Georgiana; Cimpoesu, Nicanor; Trinca, Lucia Carmen; Mareci, Daniel; Souto, Ricardo Manuel

    2016-11-01

    A new titanium base Ti-21Nb-15Ta-6Zr alloy covered with hydroxyapatite-zirconia (HA-ZrO2) 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-ZrO2 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-ZrO2 coated Ti-21Nb-15Ta-6Zr alloy will have negligible effect upon biochemical and cellular events at the bone-implant interface and could facilitate osseointegration.

  20. Simultaneous imaging of the topography and electrochemical activity of a 2D carbon nanotube network using a dual functional L-shaped nanoprobe.

    PubMed

    Lee, Eunjoo; Sung, Jungwoo; An, Taechang; Shin, Heungjoo; Nam, Hong Gil; Lim, Geunbae

    2015-05-07

    The application of nanomaterials for biosensors and fuel cells is becoming more common, but it requires an understanding of the relationship between the structure and electrochemical characteristics of the materials at the nanoscale. Herein, we report the development of scanning electrochemical microscopy-atomic force microscopy (SECM-AFM) nanoprobes for collecting spatially resolved data regarding the electrochemical activity of nanomaterials such as carbon nanotube (CNT) networks. The fabrication of the nanoprobe begins with the integration of a CNT-bundle wire into a conventional AFM probe followed by the deposition of an insulating layer and cutting of the probe end. In addition, a protrusive insulating tip is integrated at the end of the insulated CNT-bundle wire to maintain a constant distance between the nanoelectrode and the substrate; this yields an L-shaped nanoprobe. The resulting nanoprobes produced well-fitted maps of faradaic current data with less than 300 nm spatial resolution and topographical images of CNT networks owing to the small effective distance (of the order of tens of nanometers) between the electrode and the substrate. Electrochemical imaging using the L-shaped nanoprobe revealed that the electrochemical activity of the CNT network is not homogeneous and provided further understanding of the relationship between the topography and electrochemical characteristics of CNT networks.