Relevant bibliographies by topics / Electrochemical interface / Dissertations / Theses
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Dissertations / Theses on the topic 'Electrochemical interface'

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Published: 4 June 2021
Last updated: 2 February 2022

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1

Bohm, Sivasambu. "Optical and electrochemical studies of the silicon/electrolyte interface." Thesis, University of Bath, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362286.

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2

Harlow, G. S. "Surface X-ray diffraction studies of the electrochemical interface." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3003643/.

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This thesis describes the application of in-situ surface X-ray diffraction (SXRD) experiments to the study of electrochemical interfaces. Measurements performed at synchrotron radiation facilities are used to provide in-sight into the surface structure of electrodes and the electrochemical double layer. The impact of structural changes on electrochemical reactivity, and likewise the impact of electrochemical processes on electrode structure are discussed. Measurements of the Au (111) reconstruction in alkaline solution indicate that the presence of CO causes the partial lifting of the reconstruction; it is suggested that this leads to an increase in defects and this is the underlying reason for CO promoted gold catalysis. In-situ SXRD measurements with a non-aqueous electrolyte are presented, representing a technological advance in the study of electrochemical interfaces. Crystal truncation rods (CTRs) measured at the Pt (111) / non-aqueous acetonitrile interface are used to determine the structure of both the electrode surface and the electrolyte close to the interface. The results indicate that acetonitrile undergoes a potential dependant reorientation but, in the presence of molecular oxygen, the acetonitrile molecules close to the electrode are dissociated and therefore cannot reorient. Measurements of CTRs at the Pt (111) / electrolyte interface for several aqueous electrolytes are combined with CTRs measured in non-aqueous acetonitrile to explore the dependence of surface relaxation on adsorption. Fits to CTRs are also used to determine the double layer structure at aqueous Pt (111) / acetonitrile interfaces and how it varies with acetonitrile concentration. The results indicate that the acetonitrile adsorption increases with concentration and that the double layer region compresses.
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3

Wilson, Natalie Elizabeth. "In-situ and model infrared studies of the electrochemical interface." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313195.

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4

Yamada, Yuki. "Studies on Electrochemical Reactions at Interface between Graphite and Solution." 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/126811.

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5

Guymon, Clint. "MPSA effects on copper electrodeposition : understanding molecular behavior at the electrochemical interface /." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1112.pdf.

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6

Abel, Julia Catherine. "Investigation of the electrode/electrolyte interface using ultra fast electrochemical ellipsometry." Thesis, University of Newcastle Upon Tyne, 2001. http://hdl.handle.net/10443/799.

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Electrochemical ellipsometry is employed to determine the real and imaginary parts of the refractive index and the thickness of thin films as functions of the potential applied to the electrode upon which the film is grown. The relatively recent advent of an analyser with no moving parts, the Stokesmeter, has removed previous time restraints and allows microsecond resolution. The Newcastle system is extremely novel, using a Stokesmeter, and thus being capable of 325 gs resolution, and also being electrochemically interfaced. The ellipsometric studies have concentrated on the growth and behaviour of a series of electroactive polymers derived from salicylaldehydes (Salens). [Ni(SaltMe)] and [Ni(SaIdMe)] were found to yield stable homogeneous films upon polymerisation, however while the behaviour during film growth was similar, marked differences were observed during potential cycling, poly[Ni(SaIdMe)] showing a marked decrease in thickness near the anodic limit not observed for poly[Ni(Saltme)], indicating that even minor changes to ligand structure well away from the site of polymerisation may have significant effects on the resulting film. The behaviour of poly[Ni(OMeSaltMe)] during polymerisation is more complicated; initially a homogeneous film is produced, however about half way through the growth process the film becomes inhomogeneous, and remains so during subsequent potential cycling. This behaviour was also observed for poly[Pd(OMeSalen)], indicating electron donating groups around the phenyl rings of the ligand have a profound effect on the nature of the polymer films, possibly far more so than the identity of the central metal.
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7

Zhao, Meng. "Understanding Electrochemical Interface Properties by Comprehensive Self-Consistent Density Functional Theory." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1491315734773944.

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8

Nolan, Melissa A. "Microfabricated iridium arrays : failure mechanisms, investigation of the Hg-Ir interface and their use in Cu or Hg determination /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1999.

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Thesis (Ph.D.)--Tufts University, 1999.
Adviser: Samuel P. Kaunaves. Submitted to the Dept. of Chemistry. Includes bibliographical references (leaves 190). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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9

Janek, Jürgen, and Björn Luerßen. "Study of electrochemical interface processes by locally resolving photoelectron spectroscopy and microscopy." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-186682.

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10

Guymon, Clint Gordon. "MPSA Effects on Copper Electrodeposition: Understanding Molecular Behavior at the Electrochemical Interface." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/333.

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In this work the structure of the electrochemical metal-liquid interface is determined through use of quantum mechanics, molecular simulation, and experiment. Herein are profiled the molecular dynamics details and results of solid-liquid interfaces at flat non-specific solid surfaces and copper metal electrodes. Ab initio quantum-mechanical calculations are reported and define the interatomic potentials in the simulations. Some of the quantum-mechanical calculations involve small copper clusters interacting with 3-mercaptopropanesulfonic acid (MPSA), sodium, chloride, bisulfate and cuprous ions. In connection with these I develop the electrode charge dynamics (ECD) routine to treat the charge mobility in a metal. ECD bridges the gap between small-scale metal-cluster ab initio calculations and large-scale simulations of metal surfaces of arbitrary geometry. As water is the most abundant surface species in aqueous systems, water determines much of the interfacial dynamics. In contrast to prior simulation work, simulations in this work show the presence of a dense 2D ice-like rhombus structure of water on the surface that is relatively impervious to perturbation by typical electrode charges. I also find that chloride ions are adsorbed at both positive and negative electrode potentials, in agreement with experimental findings. Including internal modes of vibration in the water model enhances the ion contact adsorption at the solid surface. In superconformal filling of copper chip interconnects, organic additives are used to bottom-up fill high-aspect ratio trenches or vias. I use molecular dynamics and rotating-disk-electrode experiments to provide insight into the function of MPSA, one such additive. It is concluded that the thiol head group of MPSA inhibits copper deposition by preferentially occupying the active surface sites. The sulfonate head group participates in binding the copper ions and facilitating their transfer to the surface. Chloride ions reduce the work function of the copper electrode, reduce the binding energy of MPSA to the copper surface, and attenuate the binding of copper ions to the sulfonate head group of MPSA.
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11

Janek, Jürgen, and Björn Luerßen. "Study of electrochemical interface processes by locally resolving photoelectron spectroscopy and microscopy." Diffusion fundamentals 12 (2010) 26, 2010. https://ul.qucosa.de/id/qucosa%3A13875.

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12

Jaegermann, Wolfram. "Oxide Thin Film Li-Battery Materials: Synthesis, Interface Properties and Electrochemical Performance." Diffusion fundamentals 21 (2014) 3, S.1, 2014. https://ul.qucosa.de/id/qucosa%3A32391.

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13

Duclairoir, Florence. "Electrochemical control of supramolecular structures in solution and at the solid/liquid interface." Thesis, Heriot-Watt University, 2003. http://hdl.handle.net/10399/313.

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14

Dai, Yifan. "ENGINEERING THE BIO-ELECTRODE INTERFACE FOR ELECTROCHEMICAL BIOSENSORS WITH SENSITIVITY, ACCURACY AND SIMPLICITY." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1587470062118459.

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15

Stevens, Anthony Clark 1960. "CHARACTERIZATION OF ION-SELECTIVE ELECTRODES BY ELECTROCHEMICAL STUDIES OF ION TRANSFER AT THE LIQUID/LIQUID INTERFACE." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/276364.

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16

Zhang, Jian, Tao Wang, Darius Pohl, Bernd Rellinghaus, Renhao Dong, Shaohua Liu, Xiaodong Zhuang, and Xinliang Feng. "Interface Engineering of MoS2/Ni3S2 Heterostructures for Highly Enhanced Electrochemical Overall Water Splitting Activity." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-235457.

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To achieve sustainable production of H2 fuel through water splitting, low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are required to replace Pt and IrO2 catalysts. Here, for the first time, we present the interface engineering of novel MoS2/Ni3S2 heterostructures, in which abundant interfaces are formed. For OER, such MoS2/Ni3S2 heterostructures show an extremely low overpotential of ~218 mV at 10 mA cm-2, which is superior to that of the state-of-the-art OER electrocatalysts. Using MoS2/Ni3S2 heterostructures as bifunctional electrocatalysts, an alkali electrolyser delivers a current density of 10 mA cm-2 at a very low cell voltage of ~1.56 V. In combination with density function theory (DFT) calculations, this study demonstrates that the constructed interfaces synergistically favor the chemisorption of hydrogen and oxygencontaining intermediates, thus accelerating the overall electrochemical water splitting.
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17

Johnson-Lynn, Sarah Elizabeth. "Novel electrochemical patterning of titanium alloy to control osteogenesis at the bone-implant interface." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2407.

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The aims of this thesis were to fully characterise the surface properties of titanium alloy treated with a novel process of electrochemical etching and to assess the effect of these surfaces on osseointegration and the behaviour of osteoblasts. In vitro investigation was performed using rat osteoblasts and human mesenchymal cells. Significant differences were observed in cell polarity and cell area between cells cultured on 3V and 5V and those treated at 9V. Significantly greater mean focal adhesion area and mean number of focal adhesions per unit cell area were also observed between the 3V and 5V treated surfaces compared to the 9V treated surfaces. Longer term experiments revealed no significant changes in the levels of alkaline phosphatase activity between cells cultured on the different surfaces. After 28 days in culture, cells were stained for mineralised deposits and no significant differences were seen in the total area of bone nodules found on the experimental surfaces. To assess the influence of the treated surfaces on bone cell biology, immunofluorescence was used to localise cadherin-11 and activity and inhibition assays were performed for small GTPases of the Rho family. On the 9V treated surfaces, significantly increased staining for cadherin-11 was seen, as well as significantly greater RhoA activity. In vivo experiments were performed with electrochemically treated titanium implants in a rat tibia model. Analysis of micro-CT images of retrieved tibias revealed a significantly greater area of mineralised bone matrix in contact with the implant surface for the 9V treated surfaces and the same trend was observed on histomorphometric analysis. High variability in the mechanical testing data meant that no significant differences were seen, but a trend for greater load to failure of the bone-implant interface was observed for the 3V treated surfaces.
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18

Bennett, Raffeal A. "Characterization of the Solid-Electrolyte Interface on Sn Film Electrodes by Electrochemical Quartz Crystal Microbalance." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1399048324.

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19

Santhanakrishna, Anand Kumar. "Piezoelectric ZnO Nanowires as a Tunable Interface Material for Opto-Electronic Applications." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7926.

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Organic electronic devices are sustainable alternatives to the conventional electronics, due to their advantages of low cost, mechanical flexibility and wide range of applications. With the myriad list of organic materials available today, the opportunities to imagine new innovative devices are immense. Organic electronic devices such as OLEDs (organic light emitting diode), OPVs (Organic photovoltaics) and OFETs (organic field effect transistors) are among the leading device categories. Although OLED’s have been a huge commercial success, other categories are not lagging. Radical thinking is necessary to improve on the current performances of these devices. One such thinking is to combine the versatile ZnO (Zinc Oxide) material to organic semiconductors. This can be achieved by exploiting the dual nature of ZnO’s semiconducting and piezoelectric property. Many devices have used ZnO in combination with organic semiconductors for applications ranging from sensors, photovoltaics, OFET’s, memory and many others. The goal of the work is to incorporate the piezoelectric nature of hydrothermally grown ZnO nanowires for Opto-electronic applications. Although the initial research work was done on incorporating the piezo effect of bulk grown ZnO nanowires in improving the efficiency of an OPV, we discovered a unique memory effect in this device by incorporating ZnO nanowires in an inverted organic photovoltaic architecture. The device switched between a rectifying response in dark to resistive behavior under illumination with a finite transition time and was reversible. Since then we decided to explore few of the opto-electronic applications of this technology. The synthesis and characterization of crystalline ZnO nanowires, nanoforest and planar ZnO nanofilm are reported along with the application of these ZnO nanostructures in optoelectronic devices. Noncentro symmetry of crystalline ZnO nanostructures makes it an excellent candidate to be used as piezo functional material and these nanostructures are characterized using electrochemical cell containing ZnO electrode as the working electrode. ZnO nanostructures like nanowires, nanoforest and planar nanofilm are similarly characterized for piezo property using electrochemical technique. Different devices require distinguishing physical and electrical properties of ZnO nanostructures, hence morphology, effect of pre-strain, surface area, surface coverage and thickness of these nanostructures were evaluated for its piezoresponse. It is shown that it was possible to obtain similar piezoresponse among different ZnO nanostructures in addition to taking advantage of the structural benefits among various categories of nanostructures as per requirement. The presented research can be used as the proof-of-the-concept that ZnO nanostructures can be designed and fabricated with a prestrain to adjust the piezo response of the material under external forces. Therefore, the structure with the prestrain can be employed in various electronic and optical devices where the piezo voltage can be used for adjusting the energy band bending at an interface.
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20

Geagea, Maya. "Nouvelles architectures de surfaces d’échanges de piles à combustible de type SOFC pour l’amélioration de l’efficacité électrochimique." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEM046/document.

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Le présent travail souhaite explorer théoriquement et expérimentalement de quelle manière l’augmentation des surfaces d’échange par l’architecturation mésoscopique des interfaces électrode/électrolyte dans une SOFC à anode support pourrait améliorer ses performances. D’abord, une optimisation des caractéristiques microstructurales de l’anode a été effectuée par ajustement de la composition initiale de la barbotine, favorisation de la percolation du réseau de Ni par une microstructure « hiérarchique » et des mesures de perméabilités aux gaz identifiant le choix de l’anode. Ensuite, un modèle électrochimique a montré une augmentation des courants d’échange par rapport à la surface plane dans le cas d’un motif périodique pour une épaisseur d’électrolyte sensiblement plus petite que les dimensions du motif. Ce dernier doit présenter des singularités concaves et convexes de façon à confiner le matériau d’électrode au voisinage de l’interface, ainsi que des caractéristiques géométriques réduisant la surtension de concentration. De telles architectures ont été réalisées, par des techniques de mise en forme des céramiques, sur des anodes auto-supportées (YSZ + Ni) sur lesquelles une couche mince d’électrolyte (YSZ) a été déposée, puis l’ensemble co-fritté. Pour finaliser la cellule, une barrière de diffusion (CGO) et une cathode bicouche (LSCF48 + CGO / LSCF48) ont ensuite été déposées puis frittées. Les premiers résultats électriques et électrochimiques montrent une augmentation de la densité de courant de130 à 300 mA.cm-2 à une tension d’opération de 0,7 V, qui reste plus élevée que ce que prévoyait la modélisation. Les résultats sont discutés ici en termes de géométrie du motif et de son évolution au cours du frittage, ainsi que des surtensions d’activation et de concentration
The present work aims to explore, theoretically and experimentally, how the increase of exchange surfaces via the mesoscopic scale corrugation of electrode / electrolyte interfaces in an anode-supported SOFC could improve its performance. First, an optimization of the microstructural characteristics of the anode was performed by adjusting the initial composition of the slurry, favoring the percolation of the network of Ni by a "hierarchical" microstructure and gas permeability measurements identifying the choice of the anode. Next, an electrochemical model showed an increase in the exchange currents with respect to the planar surface in the case of a periodic pattern for an electrolyte thickness substantially smaller than the dimensions of the pattern. The latter must have concave and convex singularities so as to confine the electrode material in the vicinity of the interface, as well as geometrical characteristics reducing the concentration overvoltage. Such architectures have been carried out by ceramic shaping techniques on self-supported anodes (YSZ + Ni) on which a thin layer of electrolyte (YSZ) has been deposited, and then the co-sintered along with the anode. To finalize the cell, a diffusion barrier (CGO) and a bi-layered cathode (LSCF48 + CGO / LSCF48) were then deposited and then sintered. The first electrical and electrochemical results show an increase in the current density from 130 to 300 mA.cm-2 at an operating voltage of 0.7V, which is still higher than what was anticipated by modeling, reaching more than the double of the value for flat interfaces. The results are discussed here in terms of geometry of the pattern and its evolution during sintering, as well as activation and concentration overvoltages
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21

Abshere, Travis Arthur. "A picosecond photoluminescence and electrochemical study of the n-GaAs/elctrolyte interface in a nonaqueous photoelectrochemical cell /." view abstract or download file of text, 2000. http://wwwlib.umi.com/cr/uoregon/fullcit?p9978241.

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Thesis (Ph. D.)--University of Oregon, 2000.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 122-126). Also available for download via the World Wide Web; free to University of Oregon users.
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22

Maffre, Marion. "Électrolytes aqueux concentrés pour applications électrochimiques." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTS088.

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Les électrolytes aqueux concentrés, appelés « water-in-salt » (WIS) ont récemment émergé comme une nouvelle classe d'électrolytes. Ils permettent d’augmenter la fenêtre de stabilité électrochimique de l'eau, thermodynamiquement limitée à 1,23 V, grâce au décalage des potentiels d'évolution de l'hydrogène (HER) et de l'oxygène (OER). Ils ouvrent ainsi la voie au développement de batteries rechargeables aqueuses.Ce travail de thèse s'est concentré sur la détermination des facteurs responsables du décalage du potentiel d’OER lorsque la concentration en sel augmente. Dans le but d’atteindre cet objectif des études théoriques et expérimentales ont été menées. Dans un premier volet, la contribution de la diminution de la quantité d’eau libre sur le décalage du potentiel d’OER a été investie. Pour cela ; d’une part l’effet de la concentration en sel sur l’activité de l’eau a été quantifié. D’autre part, l’impact de l’activité de l’eau sur le potentiel de Nernst d’OER a été déterminé. Dans un second volet, l’effet de l’activité de l’eau ainsi que l’effet stérique des anions sur le potentiel d’OER ont été évalués, en employant l’équation de Butler-Volmer. Ces deux études ont été rendues possible par l’adaptation des formalismes communément utilisés pour les électrolytes classiques dilués. Dans un troisième volet, les processus chimiques et électrochimiques se produisant en potentiels positifs ont été étudiés. L’ensemble des travaux réalisés ont permis de démontrer que l’oxydation de l’eau n’est pas l’unique réaction en potentiels positifs. De plus, il a été mis en évidence que les processus redox impliqués sont complexes et conduisent à la formation d'un film à la surface de l'électrode positive
Concentrated aqueous electrolytes, called water-in-salt (WIS), have recently emerged as a new class of electrolytes. They permit to widen the electrochemical stability window of water, thermodynamically limited to 1.23 V. This is occurring because hydrogen reduction (HER) and oxygen oxidation (OER) reactions are shifted. They are currently attracting major interest for the trending development of aqueous rechargeable batteries.This thesis work focused on the factors causing the shift in the onset potential of the oxygen evolution reaction to more positive values with the increase of salt concentration. In order to reach this goal, theoretical and experimental studies were carried out. In a first part, the contribution of the decrease in the amount of free water on the shift of the water oxidation potential was investigated. For this, on one hand the effect of salt concentration on water activity was quantified. On the other hand, the impact of water activity on the Nernst potential of OER was determined. In a second part, the effect of water activity as well as the steric effect of anions on the OER potential was evaluated, using the Butler-Volmer equation. These two studies were realized by adapting the formalisms commonly used for conventional dilute electrolytes. In a third component, the chemical and electrochemical processes occurring in positive potentials were studied. All the work carried out has shown that water oxidation is not the only oxidation reaction occurring at a high positive potential. Moreover, it has been shown that the redox processes involved are complex and lead to the formation of a film on the surface of the positive electrode
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Weiher, Norbert. "Combined in situ and ex situ studies of an electrochemical interface investigation of anodic oxide layers on gold /." [S.l. : s.n.], 2003. http://www.diss.fu-berlin.de/2003/15/index.html.

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24

Dogel, Jana. "Electrochemical SPM study of 2D and 3D phase formation of Zn at the ionic liquid, Au(111) interface." Karlsruhe : Univ.-Verl, 2004. http://deposit.d-nb.de/cgi-bin/dokserv?idn=971617570.

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25

Valencia, Violeta. "Electrochemical Characterization Of Zinc-Rich Epoxy Primer-Cnt Nanocoating / Steel Interface In Co2 Saturated Under Different Flow Conditions." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1431108599.

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26

Feng, Shi. "Elucidation of hydrogen oxidation kinetics on metal/proton conductor interface." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/48941.

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High temperature proton conducting perovskite oxides are very attractive materials for applications in electrochemical devices, such as solid oxide fuel cells (SOFCs) and hydrogen permeation membranes. A better understanding of the hydrogen oxidation mechanism over the metal/proton conductor interface, is critical for rational design to further enhance the performances of the applications. However, kinetic studies focused on the metal/proton system are limited, compared with the intensively studied metal/oxygen ion conductor system, e.g., Ni/YSZ (yttrium stabilized zirconia, Zr₁-ₓYₓO₂-δ). This work presents an elementary kinetic model developed to assess reaction pathway of hydrogen oxidation/reduction on metal/proton conductor interface. Individual rate expressions and overall hydrogen partial pressure dependencies of current density and polarization resistance were derived in different rate limiting cases. The model is testified by tailored experiments on Pt/BaZr₀.₁Ce₀.₇Y₀.₁Yb₀.₁O₃-δ (BZCYYb) interface using pattern electrodes. Comparison of electrochemical testing and the theoretical predictions indicates the dissociation of hydrogen is the rate-limiting step (RLS), instead of charge transfer, displaying behavior different from metal/oxygen ion conductor interfaces. The kinetic model presented in this thesis is validated by high quantitative agreement with experiments under various conditions. The discovery not only contributes to the fundamental understanding of the hydrogen oxidation kinetics over metal/proton conductors, but provides insights for rational design of hydrogen oxidation catalysts in a variety of electrochemical systems.
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27

Bhatnagar, Purva. "A microcontroller-based Electrochemical Impedance Spectroscopy Platform for Health Monitoring Systems." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439307617.

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28

Jeganathan, Akilavasan [Verfasser], Frank [Gutachter] Marlow, and Ferdi [Gutachter] Schüth. "Liquid-liquid interface investigations using electrochemical impedance spectroscopy / Akilavasan Jeganathan ; Gutachter: Frank Marlow, Ferdi Schüth ; Fakultät für Chemie und Biochemie." Bochum : Ruhr-Universität Bochum, 2021. http://d-nb.info/1230631445/34.

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29

Protsailo, Lesia V. "Characterization of the electrode/SAM/electrolyte interface and intermolecular interactions in solutions using electrochemical impedance spectroscopy and ATR-FTIR spectroscopy /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.

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Dogel, Jana [Verfasser]. "Electrochemical SPM study of 2D and 3D phase formation of Zn at the ionic liquid, Au(111) interface / Jana Dogel." Karlsruhe : Univ.-Verl. Karlsruhe, 2004. http://d-nb.info/971617570/34.

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31

Öhman, Maria. "An in situ spectro-electrochemical study of aluminium/polymer interfaces : development of ATR-FTIR and its integration with EIS for corrosion studies." Licentiate thesis, KTH, Fibre and Polymer Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4237.

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In order to extend the applications of aluminium, organic coatings may be applied on sheet materials, for instance for corrosion protection or aesthetic surface finish purposes in the automotive and construction industries, or on foil materials in the flexible packaging industry.

The most common mechanisms for deterioration and structural failure of organically coated aluminium structures are triggered by exposures to the surrounding environment. Despite the great importance to elucidate the influence of exposure parameters on a buried aluminium/polymer interface, there is still a lack of knowledge regarding the mechanisms that destabilise the structure. It is generally believed that a detailed in situ analysis of the transport of corroding species to the buried interface, or of surface processes occurring therein, is most difficult to perform at relevant climatic and real-time conditions.

In this work, Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) in the Kretschmann-ATR configuration was successfully applied to in situ studies of the transport of water and ionic species through polymer films to the aluminium/polymer interface upon exposure to ultra pure deionised water and to a 1 M sodium thiocyanate (NaSCN) model electrolyte. Other main processes distinguished were the formation of corrosion products on the aluminium surface and swelling of the surface-near polymer network. Hence, in situ ATR-FTIR was capable to separate deterioration-related processes from each other.

To perform more unambiguous interpretations, a spectro-electrochemical method was also developed for in situ studies of the buried aluminium/polymer interface by integrating the ATR-FTIR technique with a complementary acting technique, Electrical Impedance Spectroscopy (EIS). While transport of water and electrolyte through the polymer film to the aluminium/polymer interface and subsequent oxidation/corrosion of aluminium could be followed by ATR-FTIR, the protective properties of the polymer as well as of processes at the aluminium surface were simultaneously studied by EIS. The integrated set-up provided complementary information of the aluminium/polymer sample investigated, with ATR-FTIR being sensitive to the surface-near region and EIS being sensitive to the whole system. While oxidation/corrosion and delamination are difficult to distinguish by EIS, oxide formation could be confirmed by ATR-FTIR. Additionally, while delamination and polymer swelling may be difficult to separate with ATR-FTIR, EIS distinguished swelling of the polymer network and also identified ultimate failure as a result of delamination.

The capability of the integrated ATR-FTIR / EIS in situ technique was explored by studying aluminium/polymer systems of varying characteristics. Differences in water and electrolyte ingress could be monitored, as well as metal corrosion, polymer swelling and delamination.

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32

Agyekum, Isaac. "Electrochemical Studies of Reactions in Small Volumes Less Than 1 Femto Litres." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/1316.

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Electrochemical methods have been used to study electron transfer reactions at the interface between an aqueous phase of less than 1 femto liters in volume and a bulk organic phase. The small aqueous phase is formed at the end of a slightly recessed platinum electrode. When a negative potential is applied between the Pt electrode and the aqueous phase, Ru(NH3)63+ in the aqueous phase could be reduced to Ru(NH3)62+. Because the volume of the aqueous phase is very small, the electrochemically formed Ru(NH3)62+ could instantly reach the interface between the aqueous phase and the organic phase which contains 7,7,8,8-Teteracyanoquinodimethane (TCNQ), and be oxidized to form Ru(NH3)63+ by giving electrons to TCNQ at the interface. Our results showed a positive shift in the E1/2 comparing the reaction undertaken in the recessed cavity and the bulk solution.
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33

Taranovskyy, Andriy [Verfasser]. "Study of dynamic processes at the electrochemical interface by in situ high speed STM: surface diffusion and adsorbate interactions / Andriy Taranovskyy." Kiel : Universitätsbibliothek Kiel, 2012. http://d-nb.info/1029083754/34.

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34

Gomes, Wyllerson Evaristo 1983. "Estudo da interface sólido/líquido aplicando a microbalança de cristal de quartzo com eletrodos funcionalizados." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276941.

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Orientador: David Mendez Soares
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Neste trabalho, pesquisamos o uso de filmes autoorganizados sobre o eletrodo de ouro da microbalança de cristal de quartzo eletroquímica, EQCM. Focamos a pesquisa na interação física da superfície sólida funcionalizada com o meio líquido. Desenvolvemos uma metodologia para compreender a dinâmica de variação dos parâmetros medidos, pela EQCM durante um experimento (perturbação) em meio líquido. Introduzimos a representação bidimensional da variação da freqüência de ressonância e da resistência de ressonância do cristal de quartzo da EQCM, ?f e ?R respectivamente, durante uma perturbação, usando o tempo como parâmetro. A metodologia foi utilizada para soluções aquosas de sais, álcool, líquidos apolares como ciclohexano, n-hexano, soluções de sacarose. Mostramos que líquidos reais apresentam viscoelasticidade. Também testamos a perturbação causada pela aplicação de campo elétrico nas interfaces sólido/soluções iônicas em condições em que o eletrodo é polarizável. Mostramos a possibilidade de formação de nanoestruturas gasosas, nanobolhas. Estendemos a pesquisa para a superfície do ouro funcionalizado com filmes de tiol, S-layers (proteínas de membrana de bactéria), e adsorção de lipossomos zwiteriônicos. A interface sólido/líquido também foi estudada relativamente às características hidrofóbicas da funcionalidade devido à sua microestrutura superficial (superfície superhidrofóbica). Usamos as técnicas de microscopia de força atômica, AFM, e de Raman confocal, paralelamente às nossas pesquisas com a EQCM. Para complementar o estudo de campos elétricos aplicados a interfaces, estudamos também os efeitos macroscópicos da aplicação desses campos a líquidos dielétricos como a água. Pesquisamos o fenômeno da ponte líquida usando líquidos dielétricos isolantes apróticos
Abstract: In this work, we have studied the use of self-assembling films onto gold electrode of the electrochemical quartz crystal microbalance, EQCM. The main objective is to understand the physical interaction of the functionalized solid surface with the liquid medium. We have developed a methodology to understand the dynamics of variation of the parameters measured by the EQCM in liquid medium. We also have introduced the two-dimensional representation of the variation of resonance frequency and resonance resistance of the quartz crystal of the EQCM, ?f and ?R respectively. The measurements were taken during a perturbation, using time as parameter. The methodology was used for aqueous salt solutions, alcohol, nonpolar liquids such as cyclohexane, n-hexane and sucrose solutions. We showed that real liquids exhibit viscoelasticity. We also tested the perturbation caused by the application of electric field at solid interfaces/ionic solutions, under conditions in which the electrode is polarizable. We showed the possibility of formation of gaseous nanostructures, nanobubbles. We extended the study to gold electrode thiol-functionalized surfaces, gold surfaces covered by S-layers films (membrane proteins of bacteria), and then adsorption of zwitterionic liposomes. The solid/liquid interface was also studied in relation to hydrophobic functionality due to its surface microstructure (superhydrophobic surface). We use the atomic force microscopy, AFM, and confocal Raman techniques, parallel to our research with EQCM. In addition to the study of electric fields applied to interfaces, we also studied the macroscopic effects of the application of these fields to the dielectric liquids like water. We researched the phenomenon of liquid bridge using insulating dielectric aprotic liquids
Doutorado
Física
Doutor em Ciências
2010/140031-3
CNPQ
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35

Nilsson, Stefan. "Development of Sheathless Electrospray Mass Spectrometry and Investigations of Associated Electrochemical Processes – A Fairy Tale." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4293.

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36

Yoon, Junro. "A Study of Interface Reaction of Li0.35La0.55TiO3-Li2CO3 and Its Effect on Potentiometric CO2 Gas Sensors." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354666091.

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37

Lahiri, Indranil. "Carbon Nanotube Based Systems for High Energy Efficient Applications." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/508.

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In the current age of fast-depleting conventional energy sources, top priority is given to exploring non-conventional energy sources, designing highly efficient energy storage systems and converting existing machines/instruments/devices into energy-efficient ones. ‘Energy efficiency’ is one of the important challenges for today’s scientific and research community, worldwide. In line with this demand, the current research was focused on developing two highly energy-efficient devices – field emitters and Li-ion batteries, using beneficial properties of carbon nanotubes (CNT). Interface-engineered, directly grown CNTs were used as cathode in field emitters, while similar structure was applied as anode in Li-ion batteries. Interface engineering was found to offer minimum resistance to electron flow and strong bonding with the substrate. Both field emitters and Li-ion battery anodes were benefitted from these advantages, demonstrating high energy efficiency. Field emitter, developed during this research, could be characterized by low turn-on field, high emission current, very high field enhancement factor and extremely good stability during long-run. Further, application of 3-dimensional design to these field emitters resulted in achieving one of the highest emission current densities reported so far. The 3-D field emitter registered 27 times increase in current density, as compared to their 2-D counterparts. These achievements were further followed by adding new functionalities, transparency and flexibility, to field emitters, keeping in view of current demand for flexible displays. A CNT-graphene hybrid structure showed appreciable emission, along with very good transparency and flexibility. Li-ion battery anodes, prepared using the interface-engineered CNTs, have offered 140% increment in capacity, as compared to conventional graphite anodes. Further, it has shown very good rate capability and an exceptional ‘zero capacity degradation’ during long cycle operation. Enhanced safety and charge transfer mechanism of this novel anode structure could be explained from structural characterization. In an attempt to progress further, CNTs were coated with ultrathin alumina by atomic layer deposition technique. These alumina-coated CNT anodes offered much higher capacity and an exceptional rate capability, with very low capacity degradation in higher current densities. These highly energy efficient CNT based anodes are expected to enhance capacities of future Li-ion batteries.
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38

Li, Xiaoji. "Understanding Liquid-Air Interface Corrosion of Steel in Simplified Liquid Nuclear Waste Solutions." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1365506823.

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39

Silva, Rejane Maria Pereira da. "Eletroquímica de interface óleo/água : aplicações e estudos fundamentais de parâmetros cinéticos e termodinâmicos." reponame:Repositório Institucional da UFABC, 2018.

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Orientador: Prof. Dr. Hugo Barbosa Suffredini
Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência e Tecnologia/Química, Santo André, 2018.
Este trabalho descreve a realizacao de estudos eletroquimicos fundamentais em interfaces do tipo liquido/liquido. Primeiramente, pretendeu-se compreender as diferencas na oxidacao de uma molecula modelo (ferroceno) por meio de estudos eletroquimicos relacionados a cinetica e termodinamica em diferentes situacoes. A primeira situacao enfoca a oxidacao direta do ferroceno em um eletrolito de suporte convencional aquoso e a segunda e relacionada ao ferroceno sendo adicionado diretamente em oleo mineral que quando em contato com o eletrolito de suporte aquoso, forma uma interface do tipo oleo/agua. Experimentos adicionais tambem foram conduzidos em uma emulsao, que foi constituida por ferroceno em oleo misturados com eletrolitos convencionais e cloreto de tetrabutilamonio (CTBA). Uma placa de diamante dopado com boro (DDB) foi usada como eletrodo de trabalho. Observou-se um deslocamento de aproximadamente 0,07 V quando a oxidacao do ferroceno foi conduzida na interface oleo/agua em comparacao com a oxidacao direta na fase aquosa convencional. Esta mudanca de potencial tambem foi calculada usando a Teoria do Funcional da Densidade (DFT) como ferramenta teorica. Uma comparacao adicional foi realizada em relacao a interface e as emulsoes, constatando que a forca ionica e um fator determinante nesses tipos de estudos. Finalmente, as curvas de Tafel indicaram que as coordenadas da reacao do ferroceno sao diferentes quando o eletrodo e colocado na interface versus diretamente na fase aquosa, sendo que a energia de ativacao obtida para o ferroceno na agua foi de 129 kJ mol L-1 e na interface igual a 53,0 kJ mol L-1. Posteriormente, mostrou-se o uso da microextracao liquido-liquido dispersiva (DLLME) combinada com a eletroquimica de interface oleo/agua, utilizando ferroceno como molecula- modelo. Uma mistura de 150 ¿ÊL de etanol (solvente dispersante) e 50 ¿ÊL de 1-undecanol (solvente de extracao) foi injetada em 9 mL de uma solucao aquosa de ferroceno preparada em H2SO 4 1,0 x10 -3 mol L -1. Uma gota da fase organica contendo ferroceno foi inserida diretamente na superficie de um eletrodo de carbono impresso, e uma curva analitica foi obtida, ponto a ponto, com boa linearidade. O eletrodo de DDB foi utilizado para promover o calculo do coeficiente de particao, em que foi possivel calcular as concentracoes finais de ferroceno nas fases aquosa e organica como sendo iguais a 4,2 ~ 10 -4 mol L-1 e 0,15 mol L -1, respectivamente. Ao usar estes valores, o coeficiente de particao (log P) de 2,5 foi calculado. Por fim, a eletroquimica de interface oleo/agua foi aplicada para estudar a influencia do acido naftenico na corrosao do aco API-5L-X70 a temperatura ambiente a partir de um sistema bifasico constituido por petroleo/solucao aquosa. Um estudo in-situ baseou-se na espectroscopia de impedancia eletroquimica (EIS), enquanto medidas localizadas de impedancia eletroquimica (LEIS) e microscopia eletroquimica de varredura (SECM) foram utilizadas para estudar o efeito da pre-exposicao do aco ao sistema bifasico. Os resultados de LEIS e SECM mostraram que a pre-exposicao ao petroleo com acido naftenico produz uma superficie mais ativa do que apenas a solucao de sulfato. A adicao de acido naftenico ao oleo provoca corrosao. A morfologia da corrosao e caracterizada por tres regioes: i) na fase de oleo; ii) na fase aquosa e iii) em torno da interface. A corrosao foi mais evidente em torno da interface. Propoe-se um mecanismo no qual as moleculas de acidos naftenicos se auto-organizam na interface oleo/agua, gerando acidificacao local no contato trifasico entre oleo / fase aquosa / metal.
This work describes the realization of fundamental electrochemical studies at a liquid / liquid interface. Firstly, it was intended to understand the differences in the oxidation of a model molecule (ferrocene) through electrochemical studies related to kinetics and thermodynamics in different situations. The first situation focuses the direct oxidation of ferrocene in an aqueous conventional support electrolyte and the second one is when ferrocene is directly placed in mineral oil, subsequently placed in contact with an aqueous support electrolyte thereby forming an oil/water interface. Additional experiments were also conducted in an emulsion, which was constituted by ferrocene in oil and mixed with conventional electrolytes and tetrabutylammonium chloride (TBAC). A Boron-Doped Diamond Electrode (BDD) was used as the working electrode. We observed an approximately 0.07 V shift when the ferrocene oxidation was conducted at the oil/water interface compared with the direct oxidation in the conventional aqueous phase. This potential shift was also calculated using the Density Functional Theory (DFT) as a theoretical tool. An additional comparison was conducted related to the interface and emulsions, finding that the ionic strength is determining factor in these types of studies. Finally, Tafel plots indicated that reaction coordinates of the ferrocene are different when the electrode is placed at the interface versus directly in the aqueous phase, in which the activation energy obtained for ferrocene in water was 129 kJ mol L-1 and at the interface equal to 53.0 kJ mol L-1. Posteriorly, we showed the use of dispersive liquid-liquid microextraction (DLLME) combined with organic/water interface electrochemistry by using ferrocene as a model-molecule. A mixture of 150 ¿ÊL of ethanol (disperser solvent) and 50 ¿ÊL of 1-undecanol (extractant solvent) was injected into 9 mL of a ferrocene aqueous solution prepared in 1.0~10.3 mol L.1 H2SO4. Afterward, a drop of the organic phase containing ferrocene was directly inserted on a screen-printed carbon electrode and the analytical curve was obtained, point-to-point, with a good linearity. Besides that, a BDD electrode was used to promote the partition coefficient calculation, and it was possible to calculate the final concentrations of ferrocene in the aqueous and organic phases as being equal to 4.2~10.4 mol L.1 and 0.15 mol L.1, respectively. By using these values, the partition coefficient (log P) was calculated as 2.5. Finally, the oil/water interface was applied to study the role of naphthenic acid in the API.5L.X70 steel corrosion at room temperature from a biphasic system consisting of petroleum/aqueous solution. An in-situ study was based on electrochemical impedance spectroscopy, while localized measures of electrochemical impedance (LEIS) and scanning electrochemical microscopy (SECM) were used for the effect of pre-exposure from steel to biphasic system. The results LEIS and SECM showed that the pre-exposure to oil with acid produces a more active surface than just sulfate medium. Corrosion morphology is characterized by three regions: i) in oil phase; ii) in the aqueous phase, and iii) around the interface. Naphthenic acid corrosion was restricted to the area around the interface. A mechanism is proposed in which naphthenic acids self-assemble at the oil/water interface, generating local acidification at the oil/aqueous phase/metal three-phase contact.
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40

Dumaisnil, Kévin. "Élaboration et caractérisations de matériaux de cathode et d'électrolyte pour pile à combustible à oxyde solide." Thesis, Littoral, 2015. http://www.theses.fr/2015DUNK0396/document.

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L'énergie produite par des matières fossiles, pétrole et charbon, va se raréfier de manière inéluctable et couter de plus en plus cher à moyen terme. Pour pallier à la fin des matières fossiles, le développement d'énergies alternatives est indispensable. Parmi celles-ci, la production d'électricité et de chaleur à partir d'hydrogène commence à se développer grâce aux piles à combustible (PAC) depuis les très faibles puissances (des microwatts pour alimenter les capteurs) jusqu'aux fortes puissances (des Mégawatts pour l'industrie) en passant par des puissances moyennes (des kilowatts pour le résidentiel). Une PAC est constituée de 3 éléments : 2 électrodes (anode et cathode) séparées par un électrolyte. Dans cette thèse, ces 3 éléments sont constitués d'oxydes solides et la pile est appelée SOFC (Solid Oxide Fuel Cell). Les piles SOFC actuellement commercialisées fonctionnent à de très hautes températures, typiquement supérieures à 800°C. L'objectif du travail a été d'élaborer des oxydes pour diminuer cette température vers 600°C ce qui permet d'utiliser de l'acier pour contenir ces piles. Pour que la pile SOFC fonctionne à cette température, il est impératif de diminuer la résistance électrique des 2 électrodes et de l'électrolyte de manière à récupérer une tension électrique continue maximale aux bornes de la pile et aussi à faire passer un courant électrique élevé dans celle-ci. La cathode, en contact avec l'oxygène de l'air, est l'élément le plus critique à optimiser. Nous avons choisi comme matériau de cathode un matériau déjà étudié, La₀.₆Sr₀.₄Co₀.₈Fe₀.₂O₃ (LSCF) et comme électrolyte Ce₀.₉Gd₀.₁O₂ (CGO) connu comme performant en dessous de 650 °C. Nous avons élaboré ces matériaux par une méthode de chimie douce, la méthode sol-gel Péchini, et caractérisé ceuxi-ci par diffraction de rayons X et microscopie électronique à balayage. Une part importante du travail a été la caractérisation électrique à l'aide de mesures d'impédance complexe dans une large gamme de fréquence (0,05 Hz à 2 MHz) et de température (300°C à 700 °C). Le meilleur résultat a été obtenu avec une cathode composite poreuse d'épaisseur 40 µm constituée à masses égales de LSCF et de CGO déposée par sérigraphie sur une céramique dense de CGO d'épaisseur 1,5 mm. De plus, un film mince dense de LSCF d'épaisseur 0,1 µm environ a été déposé par centrifugation pour améliorer l'interface entre la cathode et l'électrolyte. À 600 °C la résistance de cette cathode a été mesurée à 0,13 Ω pour 1 cm² de cathode : cette valeur est à l'état de l'art. Une étude du vieillissement de cette cathode et de l'électrolyte a été effectuée à 600 °C pendant 1000 h en continu sous air : cela s'est traduit par une augmentation de la résistance de la cathode de 32%. Ceci peut être lié à la différence de valeurs des coefficients d'expansion thermique des matériaux de cathode et d'électrolyte
Energy made from fossil fuels, oil or coal, is becoming increasingly rare and its price will increase in the near future. Developing alternative energy sources could compensate the use of fossil fuel. Particularly, an alternative form of energy is being developed through fuel cells, through the production of electricity and heat from hydrogen. Fuel cells can provide low wattage (microwatts for sensor applications), medium wattage (kilowatts for residential applications) and high wattage (megawatts for the industry). A fuel cell consists of 3 components : 2 electrodes (anode and cathode) separated by an electrolyte. In my work, I use solid pxide materials for these three elements in order to expand on the literature of Solid Oxide Fuel Cell (SOFC). Commercialized SOFCs currently operate at very high temperatures, typically above 800°C. The objective of this study was to develop oxides that could decrease the working temperature of the cell to 600°C, which would allow the use of steel to contain these fuel cells. In order to enable the SOFC to operate at this temperature, it is imperative to decrease the electrical resistances of the two electrodes and electrolyte in order to collect a continuous voltage which is maximal at the terminals of the fuel cell, and also to have a high electric current going through the fuel cell. The cathode, in contact with the oxygen present in the atmosphere, is the most critical element to be optimized. I close as a cathode material La₀.₆Sr₀.₄Co₀.₈Fe₀.₂O₃ (LSCF), which has already been studied. As electrolyte, I used Ce₀.₉Gd₀.₁O₂ (CGO) which is known to work below 650°C. I synthesized these materials through the Pechini method, a soft chemistry sol-gel method. The materials were characterized by X-ray diffraction and scanning electron microscopy. An important aspect of this work was the electrical characterization using complex impedance measurements in a wide frequency range (0,05 Hz to 2 MHz) and temperature (300°C to 700°C). The best result was obtained with a 40 µm thick, porous, composite cathode (LSCF/CGO 50/50 wt%) was deposited by screen printing on a 1,5 mm thick and dense CGO ceramic. In addition, a dense thin film of LSCF with a thickness of about 0,1 µm was spin-coated between the cathode and the electrolyte to improve the interface. At 600°C the measured resistance of the cathode was 0,13 Ω for 1 cm² : this value is similar to the results found in the state of the art. An aging study of the cathode and the electrolyte was carried out at 600 °C for 1000 h in air : the resistance of the cathode increased of 32%. This may be related to the different values of the thermal expansion coefficients of the cathode and electrolyte materials
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41

Shrestha, Reena Amatya. "Investigations on the phenomena of accumulation and mobilization of heavy metals and arsenic at the sediment water interface by electrochemically initiated processes." Doctoral thesis, [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=977195716.

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42

Dehiwala, Liyanage Chamathka H. "In-situ scanning tunneling microscopy studies of the SEI formation on graphite anodes in propylene carbonate." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574502965210263.

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43

Bani, Hashemi Amir [Verfasser], Mantia Fabio [Akademischer Betreuer] La, Mantia Fabio [Gutachter] La, and Mauro [Gutachter] Pasta. "Electrochemical and morphological characterization of the Interface at negative electrodes in aqueous metal-ion batteries "Gas Evolution & electrodepostion Efficiency" / Amir Bani Hashemi ; Gutachter: Fabio La Mantia, Mauro Pasta ; Betreuer: Fabio La Mantia." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/1154925978/34.

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44

Basly, Jean-Philippe. "Caracterisation de inp par des methodes electrochimiques : spectroscopie d'impedance et methodes potentiostatiques." Caen, 1988. http://www.theses.fr/1988CAEN2002.

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45

Foreman, Pamela Louise. "Spectroscopic characterisation of electrochemical biosensor interfaces." Thesis, University of Glasgow, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284728.

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46

O'Brien, Emmett P. "Durability of Adhesive Joints Subjected to Environemntal Stress." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/29139.

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Environmental stresses arising from temperature and moisture changes, and/or other aggressive fluid ingressions can degrade the mechanical properties of the adhesive, as well as the integrity of an adhesive interface with a substrate. Therefore such disruptions can significantly reduce the lifetime and durability of an adhesive joint.1-4 In this research, the durability of certain epoxy adhesive joints and coatings were characterized using a fracture mechanics approach and also by constant frequency impedance spectroscopy. The shaft-loaded blister test (SLBT) was utilized to measure the strain energy release rate (G) or adhesive fracture energy of a pressure sensitive adhesive tape. In this study, support for the value of the SLBT fracture mechanics approach was obtained. The SLBT was then used to investigate the effects of relative humidity on a model epoxy bonded to silicon oxide. Lastly, the effects of water and temperature on the adhesion of a commercial filled epoxy bonded to silicon oxide was characterized and interpreted. A novel impedance sensor for investigating adhesion was developed in a collaborative effort between Virginia Tech and Hewlett-Packard. Utilizing the technique of constant frequency impedance spectroscopy, the distribution and transport of fluids at the interface of adhesive joints was measured. A broad spectrum of adhesives was tested. In addition, the effects of hygroscopic cycling on the durability of adhesive coatings were measured for the commercial filled epoxy using the device. Lastly, recommended modifications of the experimental set-up with the new sensor are proposed to improve the technique.
Ph. D.
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47

Stewart, Alan Andrew. "Electrochemical studies of polarisable liquid/liquid interfaces." Thesis, University of Edinburgh, 1990. http://hdl.handle.net/1842/11432.

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The interface between two immiscible electrolyte solutions (ITIES) has been investigated for cyclic/linear sweep voltammetry of ion transfer, facilitated ion transfer and electron transfer. Approximate analytical solutions have been derived for the different geometries of liquid/liquid interfaces which are known, i.e. planar spherical/hemispherical, micro-hole and micropipette interfaces, for both reversible and quasi-reversible charge transfer. For planar ITIES the solution is the same as for linear diffusion for electron transfer at a metal/electrolyte interface. For spherical and hemispherical ITIES new solutions have been derived which allow a kinetic analysis to be carried out on cyclic voltammetric results, without the need to use extremely high sweep rates. The solution for a spherical interface is then used to approximate a solution for a micro-hole interface by applying the approximation that microdisc and spherical electrodes are equivalent when the ratio of the radii of the spherical electrode to the microdisc electrode is 2/π. This approximation is also used to evaluate a solution for ion transfers across an interface supported at the tip of a micropipette, where the system is also fully characterised experimentally for voltammetry. Using a similar numerical method as applied to the above problems a solution was evaluated for electron transfer across a planar ITIES for both reversible and quasi-reversible reactions. For all of these approximate solutions the trends found are the same as those seen from experimental results. A method is also presented for the kinetic analysis of 'steady-state' voltammetric waves for facilitated ion transfer across an ITIES supported at the tip of a micropipette. The technique is then used to evaluate the rate of K^+ facilitated by BD18C6 and Li^+ transfer facilitated by both ETH1810 and 2,9-dibutyl-1,10-phenanthroline. The use of liquid/liquid interfaces is also investigated as an assay method for catecholamines. As well as using ion transfer at ITIES as a method to determine catecholamines the use of enzyme coupled reactions, in conjunction with stardard redox electrochemistry or liquid/liquid electrochemistry, is also discussed.
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48

Su, Xiao Ph D. Massachusetts Institute of Technology. "Organometallic redox-interfaces for selective electrochemical separations." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/109673.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, February 2017.
"October 2016." Cataloged from PDF version of thesis.
Includes bibliographical references (pages 255-295).
Electrochemical separation methods are promising due to their modularity, fast kinetics and potential integration with renewable sources. However, they are still limited in application due to high energetic costs and lack of chemical selectivity. This work explores redox-electrodes as a platform for targeting aqueous and organic contaminants with high separation factors, in the contexts of environmental water remediation, chemical product purification in organic synthesis, metal-recovery and bio-separations. The design of selective stimuli-responsive interfaces is a crucial challenge for advanced electrochemical processes. Whereas redox-electrodes are well known in sensing, catalysis and energy storage, here we focus on their unique potential for selective ion removal - cases in which one dilute compound is targeted in the presence of large excess of competing electrolyte. In particular, organometallics and associated metalcomplexes offer an attractive material platform, due to their flexible metal-ligand design and as a consequence, extensive control allowed of their electronic properties. The first major thrust is the molecular design of various organometallic species for specific interactions with charged compounds in solution. We developed a series of heterogeneous, nano-structured metallocene interfaces to control the selective sorption and release of anions, cations, and even proteins, based on electrochemical potential. In parallel, through a combination of electronic structure calculations and spectroscopy, we unraveled the unique binding mechanism between ferrocenium and organic ions demonstrating an unusual redox-mediated hydrogen-bonding between cyclopentadienyl and carboxylates; and utilize this knowledge to further tune our redox-systems to enhance chemical selectivity. We expanded our organometallic set to various bi-pyridines and functionalized metallocenes, and studied various problems ranging from reactive separations to catalytic remediation of contaminants of emerging concern. A second major thrust consists in utilizing asymmetric pseudo capacitors as the next generation configuration for electrochemical separation devices. Asymmetric systems were shown to have much higher energy storage capabilities as well as separation efficiencies. We focused on counter-electrode design, in which the redox reaction at the cathode works in tandem with the anode, thus maintaining the water chemistry by suppressing parasitic reactions which otherwise lower current efficiency. From a fundamental perspective, the novel interaction mechanisms explored in this thesis were shown to have broader implications in deionization, sensing, catalysis and energy storage. For chemical engineering, this work demonstrated redox-based electrochemical methods as an energy-efficient and sustainable route to process intensification, and paved their way for practical implementation in industry.
by Xiao Su.
Ph. D.
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49

Huang, Jimin. "Characterization of Electrochemical Interfaces by INfrared Spectroscopy." Diss., Virginia Tech, 1996. http://hdl.handle.net/10919/30301.

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The properties of electrochemical interfaces are studied using Fourier transform infrared spectroscopy. Potential difference infrared spectroscopy (PDIRS) was used in the investigation of carbon monoxide adsorbed on polycrystalline platinum electrodes. It is found that the infrared peak position of adsorbed carbon monoxide is linearly dependent on the applied electrode potential, and that the Stark tuning rate is a function of system temperature. The change in Stark tuning rate is the result of the variation of the interfacial dielectric constant with temperature. Self-assembled alkoxyalkanethiol monolayers were formed on gold substrates as surface modifiers of low dielectric constant designed to influence the interfacial capacitance. Polarization modulation infrared spectroscopy (PMIRS), ellipsometry, interfacial wetting, and cyclic voltammetry were conducted to characterize the modified interfaces. The interfacial capacitance is greatly reduced due to the adsorption of w-mercapto ethers on substrates. It was found that the solvation of the monolayer by solution is capable of improving the mass transport to maintain the Faradaic current while lowering the interfacial capacitance. The oxygen group in w-mercapto ethers at the monolayer-water interface interacts with water molecules to improve the monolayer solubility in water. The w-mercapto ether monolayers were found to be fluid-like in structure, giving better freedom to undergo structural change. The repulsion from the oxygen atoms in adjacent w-mercapto ether molecules adsorbed on the substrate introduces structural disorder to the alkyl chains in the monolayer, allowing better solvent permeation. This relieves some of the current blocking character of long chain alkanethiol monolayers. The interfacial contact angle to water for the w-mercapto ether monolayers is dependent on the oxygen position in the monolayer. 12-Methoxydodecanethiol has the lowest contact angle among all the w-mercapto ethers studied while 12-butoxydodecanethiol through 12-hexoxydodecanethiol have similar contact angles due to the ether oxygen being buried beneath several layers of methylene groups. The film thickness is roughly proportional to the total number of methylene groups in the two alkyl chains on w- mercapto ethers. w-Mercapto ethers that have a longer alkyl chain between the oxygen and thiol tend to form thicker monolayers on the substrates. In situ PMIRS measurements show that w-mercapto ether monolayers do not undergo structural change in the alkyl chains when in contact with either water or acetonitrile. The terminal methyl group, however, suffers from a shift in infrared peak position to lower frequency, and a decrease in peak height as the result of solvent load.
Ph. D.
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50

Castagnola, Valentina. "Implantable microelectrodes on soft substrate with nanostructured active surface for stimulation and recording of brain activities." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2646/.

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Les prothèses neuronales implantables offrent de nos jours une réelle opportunité pour restaurer des fonctions perdues par des patients atteints de lésions cérébrales ou de la moelle épinière, en associant un canal non-musculaire au cerveau ce qui permet la connexion de machines au système nerveux. La fiabilité sur le long terme de ces dispositifs, se présentant sous la forme d'électrodes implantables, est un facteur crucial pour envisager des applications dans le domaine des interfaces cerveau-machine. Cependant, les électrodes actuelles pour l'enregistrement et la stimulation se détériorent en quelques mois voire quelques semaines. Ce défaut de fiabilité sur le long terme, principalement lié à une réaction chronique contre un corps étranger, est induit au départ par le traumatisme consécutif à l'insertion du dispositif et s'aggrave ensuite, durant les mouvements du cerveau, à cause des propriétés mécaniques inadaptées de l'électrode par rapport à celles du tissu. Au cours du temps, l'ensemble de ces facteurs inflammatoires conduit à l'encapsulation de l'électrode par une couche isolante de cellules réactives détériorant ainsi la qualité de l'interface entre le dispositif implanté et le tissu cérébral. Pour s'affranchir de ce phénomène, la biocompatibilité des matériaux et des procédés, ainsi que les propriétés mécaniques de l'électrode doivent être pris en considération. Durant cette thèse, nous avons abordé la question en développant un procédé de fabrication simple pour réaliser des dispositifs implantables souples en parylène. Les électrodes flexibles ainsi obtenues sont totalement biocompatibles et leur compliance est adaptée à celle du tissu cérébral ce qui limite fortement la réaction inflammatoire occasionnée par les mouvements du cerveau. Après avoir optimisé le procédé de fabrication, nous avons focalisé notre étude sur les performances du dispositif et sa stabilité. L'utilisation d'une grande densité d'électrodes micrométriques, avec un diamètre de 10 à 50 µm, permet de localiser les zones d'enregistrement en rendant possible, par exemple, la conversion d'un ensemble de signaux électrophysiologiques en une commande de mouvement. En contrepartie, la réduction de la taille des électrodes conduit à une augmentation de l'impédance ce qui dégrade la qualité d'enregistrement des signaux. Ici, un polymère conducteur organique, le poly(3,4-ethylenedioxythiophene), PEDOT, a été utilisé pour améliorer les caractéristiques électriques d'enregistrement d'électrodes de petites dimensions. Le PEDOT a été déposé sur la surface des électrodes par électrochimie avec une grande reproductibilité. Des dépôts homogènes avec des conductivités électriques très élevées ont été obtenus en utilisant différents procédés électrochimiques. Grâce à l'augmentation du rapport surface/volume induit par la présence de la couche de PEDOT, une diminution significative de l'impédance de l'électrode (jusqu'à 3 ordres de grandeur) a été obtenue sur une large plage de fréquences. De tests de vieillissement thermique accéléré ont également été effectués sans influence notable sur les propriétés électriques démontrant ainsi la stabilité de la couche de PEDOT durant plusieurs mois. Les dispositifs ainsi obtenus, fabriqués en parylène avec un dépôt de PEDOT sur la surface active des électrodes, ont été testés in vitro et in vivo sur des cerveaux de souris. Un meilleur rapport signal sur bruit a été mesuré durant des enregistrements neuronaux en comparaison avec des résultats obtenus avec des électrodes commerciales. En conclusion, la technologie décrite ici, associant stabilité sur le long terme et faible impédance, a permis d'obtenir des électrodes implantables parfaitement adaptées pour le développement d'interfaces neuronales chroniques
Implantable neural prosthetics devices offer, nowadays, a promising opportunity for the restoration of lost functions in patients affected by brain or spinal cord injury, by providing the brain with a non-muscular channel able to link machines to the nervous system. The long term reliability of these devices constituted by implantable electrodes has emerged as a crucial factor in view of the application in the "brain-machine interface" domain. However, current electrodes for recording or stimulation still fail within months or even weeks. This lack of long-term reliability, mainly related to the chronic foreign body reaction, is induced, at the beginning, by insertion trauma, and then exacerbated as a result of mechanical mismatch between the electrode and the tissue during brain motion. All these inflammatory factors lead, over the time, to the encapsulation of the electrode by an insulating layer of reactive cells thus impacting the quality of the interface between the implanted device and the brain tissue. To overcome this phenomenon, both the biocompatibility of materials and processes, and the mechanical properties of the electrodes have to be considered. During this PhD, we have addressed both issues by developing a simple process to fabricate soft implantable devices fully made of parylene. The resulting flexible electrodes are fully biocompatible and more compliant with the brain tissue thus limiting the inflammatory reaction during brain motions. Once the fabrication process has been completed, our study has been focused on the device performances and stability. The use of high density micrometer electrodes with a diameter ranging from 10 to 50 µm, on one hand, provides more localized recordings and allows converting a series of electrophysiological signals into, for instance, a movement command. On the other hand, as the electrode dimensions decrease, the impedance increases affecting the quality of signal recordings. Here, an organic conductive polymer, the poly(3,4-ethylenedioxythiophene), PEDOT, has been used to improve the recording characteristics of small electrodes. PEDOT was deposited on electrode surfaces by electrochemical deposition with a high reproducibility. Homogeneous coatings with a high electrical conductivity were obtained using various electrochemical routes. Thanks to the increase of the surface to volume ratio provided by the PEDOT coating, a significant lowering of the electrode impedance (up to 3 orders of magnitude) has been obtained over a wide range of frequencies. Thermal accelerated ageing tests were also performed without any significant impact on the electrical properties demonstrating the stability of the PEDOT coatings over several months. The resulting devices, made of parylene with a PEDOT coating on the active surface of electrodes, have been tested in vitro and in vivo in mice brain. An improved signal to noise ratio during neural recording has been measured in comparison to results obtained with commercially available electrodes. In conclusion, the technology described here, combining long-term stability and low impedance, make these implantable electrodes suitable candidates for the development of chronic neural interfaces
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