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  • 251.
    Sarkar, Debasish
    et al.
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Das, Shyamashis
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Sharada, G.
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Pal, Banabir
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Shukla, Ashok
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Sarma, D. D.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    A Cost-Effective and High-Performance Core-Shell-Nanorod-Based ZnO/alpha-Fe2O3//ZnO/C Asymmetric Supercapacitor2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 6, p. A987-A994Article in journal (Refereed)
    Abstract [en]

    A novel core-shell design for nano-structured electrode materials is introduced for realizing cost-effective and high-performance supercapacitors. In the proposed core-shell design, thin shell-layers of highly pseudo-capacitive materials provide the platform for surface or near-surface-based faradaic and non-faradaic reactions together with shortened ion-diffusion path facilitating fast-ion intercalation and deintercalation processes. The highly-conducting core serves as highway for fast electron transfer toward current collectors, improving both energy and power performance characteristics of the core-shell structure in relation to pristine component materials. Furthermore, use of carbon (C)-based materials as a shell layer in either electrode not only enhances capacitive performance through double-layer formation but also provides enough mechanical strength to sustain volume changes in the core material during long-cycling of the supercapacitor improving its cycle life. In order to enhance electrochemical performance in terms of specific capacitance and rate capability via core-shell architecture and nano-structuring, an asymmetric supercapacitor (ASC) is assembled using ZnO/alpha-Fe2O3 and ZnO/C core-shell nanorods as respective negative and positive electrodes. The ASC exhibits a specific capacitance of similar to 115 F/g at a scan rate of 10 mV/s in a potential window as large as 1.8 V with a response time as short as 39 ms and retains more than 80% of its initial capacitance after 4000 cycles. Interestingly, the ASC can deliver an energy density of similar to 41 Wh/kg and a power density of similar to 7 kW/kg that are significantly higher than those reported hitherto for iron-oxide-based ASCs.

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  • 252. Schwind, Markus
    et al.
    Hosseinpour, Saman
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Langhammer, Christoph
    Zoric, Igor
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Kasemo, Bengt
    Nanoplasmonic Sensing for Monitoring the Initial Stages of Atmospheric Corrosion of Cu Nanodisks and Thin Films2013In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 160, no 10, p. C487-C492Article in journal (Refereed)
    Abstract [en]

    Nanoplasmonic sensing as a powerful experimental technique for corrosion kinetics monitoring is demonstrated. Its versatility is illustrated by studies of initial corrosion carried out on model systems consisting of copper nanodisks and extended copper films in both dry (<0.5% relative humidity, RH) and humid (65 +/- 5% RH) air. Samples with and without a protective self-assembled monolayer of octadecanethiol (ODT) were studied. Thus, we studied four different corrosion situations. Two versions of the technique were employed, direct and indirect nanoplasmonic sensing (INPS). The former used disk-shaped nanoparticles as both sample structures and sensing particles, the latter used extended films as the sample, with the nanoplasmonic sensing particles embedded under the sample. Corrosion kinetics were recorded with high sensitivity and high temporal resolution (submonolayer detection limit; temporal resolution 1-2 seconds). In dry air, six times lower oxidation rates were observed for ODT-covered Cu compared to bare Cu, demonstrating the protection efficiency of the ODT as a corrosion inhibitor. In humid air, a higher oxidation rate was measured for both bare (2.4 times higher) and ODT-covered (1.7 times higher) samples, compared to the same samples exposed to the dry air environment. Oxidation occurred first after a short induction period during which water was adsorbed. For the Cu nanodisks (direct sensing) and Cu films (indirect sensing) studied here, very similar oxidation kinetics were observed.

  • 253. Seidel, Y. E.
    et al.
    Lindström, Rakel
    Jusys, Z.
    Gustavsson, M.
    Hanarp, P.
    Kasemo, B.
    Minkow, A.
    Fecht, H. J.
    Behm, R. J.
    Stability of nanostructured Pt/glassy carbon electrodes prepared by colloidal lithography2008In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 155, no 3, p. K50-K58Article in journal (Refereed)
    Abstract [en]

    The stability of nanostructured Pt/glassy carbon (GC) model electrodes upon exposure to a realistic electrochemical/electrocatalytic reaction environment (continuous reaction, continuous electrolyte flow) was studied by microscopic techniques, X-ray photoelectron spectroscopy, and electrochemical measurements. The model electrodes consist of Pt nanostructures with well-defined sizes and regular spacing on planar GC substrates, and were fabricated using colloidal lithography techniques. Additional plasma treatments of the GC substrates prior to Pt deposition were tested to improve the stability of the resulting Pt/GC model electrodes. Both evaporation and sputter deposition were used for Pt-film fabrication. The model catalysts prepared by Pt evaporation were found to be rather unstable. The stability was significantly improved for sputter-deposited Pt films, and Pt sputter deposition on a GC substrate, pretreated first in oxygen plasma and then in Ar plasma, resulted in stable model electrodes with a fully intact layer of Pt nanostructures after the electrocatalytic experiments.

  • 254. Sharma, S.
    et al.
    Fransson, L.
    Sjostedt, E.
    Nordstrom, L.
    Johansson, Börje
    KTH, Superseded Departments, Materials Science and Engineering.
    Edstrom, K.
    A theoretical and experimental study of the lithiation of eta '-Cu6Sn5 in a lithium-ion battery2003In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, no 3, p. A330-A334Article in journal (Refereed)
  • 255.
    Sharma, Sangeeta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory.
    Fransson, Linda
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Sjöstedt, Elisabeth
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory.
    Nordström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory.
    Johansson, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    A theoretical and experimental study of the lithiation of η'-Cu6Sn5 in a lithium-ion battery2003In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, no 3, p. A330-A334Article in journal (Refereed)
    Abstract [en]

    Themechanism of Li insertion in -Cu6Sn5 to form Li2CuSn isdiscussed in detail, based on both theoretical calculations and experimentalresults. The mechanism is investigated by means of first principlescalculations, with the full potential linearized augmented plane wave method,in combination with in situ X-ray diffraction experiments. The -Cu6Sn5structure, as well as its lithiated products, were optimized andthe electronic charge density calculated in order to study thechange in bond character on lithiation. The average insertion voltageof the -Cu6Sn5-Li2CuSn transformation has been calculated to be 0.378V, in good agreement with the experimental value.                            

  • 256.
    Shin, Joon-Ho
    et al.
    ENEA (Italian National Agency for New Technologies, Energy and the Environment), IDROCOMB, Casaccia Research Center, 00060 Rome, Italy.
    Henderson, Wesley A
    Tizzani, Cosimo
    Passerini, Stefano
    Jeong, Sang S
    Kim, Ki-Won
    Characterization of solvent-free polymer electrolytes consisting of ternary PEO-LiTFSI-PYR14 TFSI2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 9, p. A1649-A1654Article in journal (Refereed)
    Abstract [en]

    The physical properties and electrochemical performance of solvent-free polymer electrolytes, consisting of poly(ethylene oxide) [P(EO)] with Li+'>Li +  Li+ and N'>N N -butyl-N'>N N -methylpyrrolidinium (PYR14+)'>(PYR + 14 ) (PYR14+) salts of bis(trifluoromethanesulfonyl)imide (TFSI), are reported. The addition of the PYR14TFSI'>PYR 14 TFSI PYR14TFSI room-temperature molten salt to the conventional P(EO)10LiTFSI'>P(EO) 10 LiTFSI P(EO)10LiTFSI polymer electrolyte results in a significant enhancement of the ionic conductivity (to 2.6&#xD7;10&#x2212;4S&#x2215;cm'>2.6×10 −4 S/cm 2.6×10−4S∕cm at 20&#xB0;C'>20°C 20°C ). Limetal&#x2215;LiFePO4'>Limetal∕LiFePO 4  Limetal∕LiFePO4 batteries making use of this new family of solid polymer electrolytes have shown a very promising low-temperature cycle life. It was found that a Limetal&#x2215;LiFePO4'>Limetal∕LiFePO 4  Limetal∕LiFePO4 cell at 20&#xB0;C'>20°C 20°C can deliver 138mAh&#x2215;g'>138mAh∕g 138mAh∕g during the first discharge, corresponding to 90% of the nominal specific capacity (154mAh&#x2215;g)'>(154mAh∕g) (154mAh∕g) , and a promisingly low capacity fading of about 0.2%/cycle over 500 cycles.

  • 257.
    Sisbandini, Ciptanti
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    The Mechanism of Capacity Enhancement in LiFePO4 Cathodes Through Polyetheramine Coating2009In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 156, no 9, p. A720-A725Article in journal (Refereed)
    Abstract [en]

    Thispaper addresses the possible mechanisms underlying the capacity enhancement throughpolyetheramine [PEA, glyceryl poly(oxypropylene)triamine] coating on LiFePO4 (Phostech Lithium) particlesurface. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared studieshave confirmed the presence of PEA on the surface bythe appearance of the N 1s peak in the XPSspectra and bands in the 2850–2960  cm−1 wavenumber range of theIR spectra. Potentiostatic measurements in organic electrolytes have shown thatthe discharge capacity is increased ca. 12% compared to theas-received material, i.e., more Fe2+/Fe3+ ions are utilized during theredox process. This is due to better wettability of theelectrolyte to the particle surface, which is indicated by theslower sedimentation of coated particles. Furthermore, cyclic voltammetry has shownthat PEA-coated particles display higher capacity than the as-received materialalso in an aqueous electrolyte, which to some extent canbe explained by the difference in wettability between the materials,but also by the protection of LiFePO4 from spontaneous formationof a Li3PO4 surface layer and Fe3+-containing solids when incontact with water.

  • 258. Smith, Leif
    et al.
    Söderbärg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Electro-chemical etch stop obtained by accumulation of free carriers without pn junction1993In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 140, no 1, p. 271-275Article in journal (Refereed)
  • 259. Soderstrom, D.
    et al.
    Lourdudoss, Sebastian
    KTH, Superseded Departments (pre-2005), Microelectronics and Information Technology, IMIT.
    Wallnas, M.
    Dadgar, A.
    Stenzel, O.
    Bimberg, D.
    Schumann, H.
    Studies on ruthenium-doped InP growth by low-pressure hydride vapor-phase epitaxy2001In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 148, no 7, p. G375-G378Article in journal (Refereed)
    Abstract [en]

    Ruthenium-doped InP (InP:Ru) has been grown by low-pressure hydride vapor-phase epitaxy (LP-HVPE) using bis(eta (5)-2,4-dimethylpentadienyl)ruthenium(II) as precursor. Ruthenium concentrations in the range 2 x 10(15) to 2 x 10(18) cm(-3) have been achieved. The Ru incorporation has been studied in terms of incorporation flux, and it is shown that the growth rate limits: the incorporation rate. From current-voltage measurements on n-InP/InP:Ru/n-InP and p-InP/InP:Ru/p-InP structures, resistivities greater than 10(3) Omega cm and greater than 10(10) Omega cm have been obtained, respectively.

  • 260. Sorar, I.
    et al.
    Rojas-González, E.A.
    Bayrak Pehlivan, I.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism of W–Ti Oxide Films: Cycling Durability, Potentiostatic Rejuvenation, and Modeling of Electrochemical Degradation2019In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, p. H795-H801Article in journal (Other academic)
    Abstract [en]

    Thin films of electrochromic W oxide and W–Ti oxide were prepared by reactive DC magnetron sputtering and were cycled voltammetrically in an electrolyte of lithium perchlorate in propylene carbonate. Film degradation was studied for up to 500 voltammetric cycles in voltage ranges between 1.5–4.0 and 2.0–4.0 V vs. Li/Li+. Optically and electrochemically degraded films were subjected to potentiostatic posttreatment at 6.0 V vs. Li/Li+ to achieve ion de-trapping and rejuvenation so that the films partly regained their original properties. Ti incorporation and potentiostatic posttreatment jointly yielded superior electrochromic properties provided the lower limit of the voltage range was above 1.6–1.7 V vs. Li/Li+. Degradation dynamics for as-deposited and rejuvenated thin films was modeled successfully by power-law kinetics; this analysis indicated coexistence of two degradation mechanisms, one based on dispersive chemical kinetics and operating universally and another, of unknown origin, rendered inactive by rejuvenation. The results of the present study are of large interest for the development of electrochromic devices with exceptional durability.

  • 261.
    Sorar, Idris
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Hatay Mustafa Kemal University, Turkey.
    Rojas González, Edgar Alonso
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Bayrak Pehlivan, Ilknur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism of W–Ti Oxide Thin Films: Cycling Durability,Potentiostatic Rejuvenation, and Modelling of Electrochemical Degradation2019In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, no 15, p. H795-H801Article in journal (Refereed)
    Abstract [en]

    Thin films of electrochromicWoxide and W–Ti oxide were prepared by reactive DC magnetron sputtering and were cycled voltammetrically in an electrolyte of lithium perchlorate in propylene carbonate. Film degradation was studied for up to 500 voltammetric cycles in voltage ranges between 1.5–4.0 and 2.0–4.0 V vs. Li/Li+. Optically and electrochemically degraded films were subjected to potentiostatic posttreatment at 6.0 V vs. Li/Li+ to achieve ion de-trapping and rejuvenation so that the films partly regained their original properties. Ti incorporation and potentiostatic posttreatment jointly yielded superior electrochromic properties provided the lower limit of the voltage range was above 1.6–1.7 V vs. Li/Li+. Degradation dynamics for as-deposited and rejuvenated thin films was modeled successfully by power-law kinetics; this analysis indicated coexistence of two degradation mechanisms, one based on dispersive chemical kinetics and operating universally and another, of unknown origin, rendered inactive by rejuvenation. The results of the present study are of large interest for the development of electrochromic devices with exceptional durability.

  • 262.
    Sparr, Mari
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Bodén, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    A Steady-State Model of the Porous Molten Carbonate Fuel Cell Anode for Investigation of Kinetics and Mass Transfer2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 8, p. A1525-A1532Article in journal (Refereed)
    Abstract [en]

    The purpose of this paper was to investigate the effect of gas phase mass transfer and the influence of different reactions on the anode performance and to understand previously made experiments better. This has been done by mathematically modeling how different effects influence the polarization curve of the anode. Some previously obtained experimental data were used as input for the model. In this study, results from using the mechanisms proposed for the hydrogen oxidation by Jewulski and Suski and Ang and Sammels, respectively, show that they are equally likely. Furthermore, the direct electrochemical oxidation of carbon monoxide only slightly influences the anode performance. The concentration gradients in the current collector are larger than inside the electrode for gases not in equilibrium when entering the current collector; this is an effect caused by the shift reaction inside the electrode. However, if the gas compositions correspond to equilibrium at the current collector, the gas composition profiles become almost uniform. The disparities of the partial pressure dependency found in earlier experiments may be explained if the inlet gas composition is assumed to be the one obtained directly after humidification and not in equilibrium, as generally assumed.

  • 263. Sukhrobov, Parviz
    et al.
    Numonov, Sodik
    Liu, Jing
    Luo, Jun
    Mamat, Xamxikamar
    Li, Yongtao
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Hu, Guangzhi
    Umeå University, Faculty of Science and Technology, Department of Physics. Key Laboratory of Chemistry of Plant Resources in Arid Regions, State Key Laboratory Basis of Xinjiang Indigenous Medicinal Plants Resource Utilization, Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi, China.
    Rapid Microwave-Assisted Synthesis of Copper Decorated Carbon Black Nanocomposite for Non-Enzyme Glucose Sensing in Human Blood2019In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, no 13, p. B1238-B1244Article in journal (Refereed)
    Abstract [en]

    The current research performs the novelty fabricated of non-enzymatic biosensor based on copper nanoparticles decorated carbon black nanocomposite modified glassy carbon electrode (Cu/DCB/GCE) by using the microwave method. The prepared nanomaterial was applied for glucose determination in biological fluids and human serum samples. The techniques of SEM, TEM, XPS, XRD, EDS and mapping tests were selected for the morphological, compositions and crystal structure characterizations of the fabricated nanocomposite. In comparison with other electrodes based on metal decorated carbon black, the Cu/DCB/GCE demonstrated the best electrocatalytic property toward glucose oxidation in 0.1 M KOH electrolyte. Cu/DCB/GCE under the optimal potential of +0.5 V in a linear range from 0.5 up to 7000 mu M with a detection limit of 0.1 mu M (S/N=3), the coefficient of correlation R-2=0.999, performed significant high sensitivity of 1595 mu A mM(-1) cm(-2). Rapid amperometric responses of the prepared biosensor in short time with 0.8-2 s were observed by addition of different glucose concentrations in alkaline solution. Modified Cu/DCB/GCE exhibited the best anti-interference property against blood cells and some blood co-existence molecules such as dopamine, uric acid, ascorbic acid, albumin, and globulin. Most importantly, Cu/DCB/GCE biosensor was used for glucose level determination in human blood serum samples. Due to the attractable structure and properties of the fabricated biosensor, it can be suggested for the future development of glucose detection design.

  • 264.
    Syväjärvi, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Anisotropic etching of SiC2000In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 147, no 9, p. 3519-3522Article in journal (Refereed)
    Abstract [en]

    The etching effect using molten KOH of micropipes and dislocations in silicon carbide single crystals is investigated. Most of the etch pits become hexagonal due to an anisotropic etching behavior. Micropipes are interconnected with dislocations, and this observation is discussed in relation to the growth process. The hexagonal pattern of micropipes is revealed by rapid etching provided by a large undersaturation. Etching from a melt gives a disintegration of the SiC crystal at the micropipe via spiral dissolution as a consequence of etching near equilibrium conditions. The Si- and C-faces are attacked by molten KOH preferentially and isotropically, respectively. The size of the micropipes with increasing etching time is studied for both the Si- and C-faces. The temperature dependence of the etch rate follows an Arrhenius dependence with an apparent activation energy of about 12-15 kcal/mol derived from measuring the etch rate and weight loss.

  • 265.
    Söderbärg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Investigation of buried etch stop layer in silicon by nitrogen implantation1992In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 139, no 2, p. 561-566Article in journal (Refereed)
  • 266. Tidblad, J.
    et al.
    Aastrup, T.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    GILDES model studies of aqueous chemistry VI: Initial so2/O 3- And so2/NO2-induced atmospheric corrosion of copper2005In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 152, no 5, p. B178-B185Article in journal (Refereed)
    Abstract [en]

    GILDES, a computer-based model of atmospheric corrosion, has been used to simulate copper exposed at room temperature to 200 ppb SO2 in combination with either NO2 or O-3 at different concentrations. The GILDES model involves the five most important regimes in atmospheric corrosion (gas, liquid, deposition, electrodic, and surface) and includes 27 aqueous species and more than 60 aqueous reactions. Under these exposure conditions copper forms cuprite (Cu2O) and various copper sulfates in both SO2 + NO2 and SO2 + O-3 mixtures, and copper hydroxynitrate in SO2 + NO2 after an incubation time of 4 h. Among these experimental observations the GILDES model correctly predicts the formation of copper sulfate (in both SO2 + O-3 and SO2 + NO2 mixtures) and copper hydroxynitrate (SO2 + NO2). It is furthermore able to predict the formation rate of copper sulfate in SO2 + O-3 mixtures, but not the formation rate of copper sulfate and copper hydroxynitrate in SO2 + NO2 mixtures.

  • 267.
    Tirén, J
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Svensson, BG
    Evaluation of boron distributions in amorphous 49BF2+-implanted silicon1991In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 138, no 2, p. 571-576Article in journal (Refereed)
  • 268.
    Törndahl, Tobias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Ottosson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Carlsson, Jan-Otto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Growth of Copper(I) Nitride by ALD Using Copper(II) Hexafluoroacetylacetonate, Water and Ammonia as Precursors2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 3, p. C146-C151Article in journal (Other academic)
    Abstract [en]

    Films of copper(I) nitride were deposited by atomic layer deposition (ALD) using copper(II) hexafluoroacetylacetonate, water, and ammonia as precursors. Introduction of a water pulse in the ALD cycle was found to be crucial for initiating film growth on both amorphous SiO2 and single-crystalline α-Al2O3(001) substrates. The water pulses generated an oxidic copper monolayer, which in a subsequent ammonia pulse was converted to the nitride. The films have been grown in the temperature range from 210to302°C . Phase pure films of Cu3N were obtained up to 265°C . At higher deposition temperatures such as 283°C , phase mixtures of Cu3N and Cu were obtained. For temperatures above 302°C films of only Cu were grown. Film growth rate was the same on the two different substrates. The films were randomly oriented on SiO2 . Completely intact films were obtained at a thickness of 20nm . The optical bandgap of the films was measured to be 1.6eV .

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  • 269.
    Usman, Muhammad
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Pilvi, Tero
    Schoner, Adolf
    Leskela, Markku
    Toward the Understanding of Stacked Al-Based High-k Dielectrics for Passivation of 4H-SiC Devices2011In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 158, no 1, p. H75-H79Article in journal (Refereed)
    Abstract [en]

    Metal insulator semiconductor structures using high-k materials have been prepared and investigated for the passivation of 4H-SiC surfaces. Alternate layers of AlN and Al2O3 were deposited on 8 nm thermally grown SiO2 on epitaxial SiC, forming multilayer stacked dielectrics. Atomic layer deposition (ALD) has been used for the deposition. Our results show that the AlN, deposited by ALD, has a columnar polycrystalline structure with boundaries related to the step bunching of SiC epitaxial layer. Capacitance-voltage measurements have been performed at room temperature, 100, 200, and 300 degrees C. Annealing of the samples was also performed at these temperatures and they were consecutively measured at room temperature. Current-voltage measurements have also been performed before and after annealing. It has been observed that the stack with a bottom layer of Al2O3, forming an interface with the thin SiO2, is more stable at high temperatures; however, its breakdown voltage is less than that of the other stack with AlN forming the bottom layer. The breakdown behavior of the stacks is also found to be different depending on the order of AlN and Al2O3 layers.

  • 270.
    Van den Steen, N.
    et al.
    Vrije Universiteit Brussel, Belgium.
    Simillion, H.
    Vrije Universiteit Brussel, Belgium.
    Thierry, Dominique
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, KIMAB.
    Terryn, H.
    Vrije Universiteit Brussel, Belgium.
    Deconinck, J.
    Vrije Universiteit Brussel, Belgium.
    Comparing modeled and experimental accelerated corrosion tests on steel2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 9, p. C554-C562Article in journal (Refereed)
    Abstract [en]

    Four different accelerated corrosion tests on steel are simulated with a Dynamic Electrolyte Film Corrosion model. Based on the time dependent temperature and humidity, combined with the presence of hygroscopic salts, a time dependent electrolyte thickness is calculated. At every timestep, the modeled film thickness dictates the corrosion current. Focussing on the thickness predictions, an elementary corrosion model is adopted to enable the corrosion depth estimations. The trends of the simulated corrosion depths are compared with experimental data obtained with an electrical resistance corrosion sensing system, demonstrating the importance of the electrolyte thickness and composition for a thorough understanding and modeling of atmospheric corrosion on steel. © The Author(s) 2017.

  • 271.
    von Kraemer, Sophie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lafitte, Benoit
    Polymer and Materials Chemistry, Department of Chemistry, Lund University.
    Puchner, Mario
    Polymer and Materials Chemistry, Department of Chemistry, Lund University.
    Jannasch, Patric
    Polymer and Materials Chemistry, Department of Chemistry, Lund University.
    Substitution of Nafion with Sulfonated Polysulfone in Membrane-Electrode Assembly Components for 60-120 °C PEMFC Operation2008In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 155, no 10, p. B1001-B1007Article in journal (Refereed)
    Abstract [en]

    To investigate the influence of sulfonated polysulfone (sPSU) in membrane–electrode assemblies (MEAs), sPSU-based gas diffusion electrodes (GDEs) and sPSU membranes were studied both as complete MEAs and as separate components in assembled MEAs at 60–120°C. The complete sPSU MEAs showed mass-transport limitations, irrespective of ion exchange capacity, compared to Nafion MEAs. Cyclic voltammetry and low-current impedance analysis revealed comparable electrochemically active catalyst areas and kinetic properties in the sPSU and Nafion GDEs, while gas-crossover measurements showed a lower gas permeability in sPSU compared to Nafion. The sPSU and Nafion GDEs, deposited on Nafion membranes, possessed comparable fuel cell characteristics at 120°C and 100% relative humidity, demonstrating no considerable limitations when utilizing sPSU as an alternative to Nafion in the GDE, thus implying a sufficient gas permeability in the sPSU GDE at high humidity. Furthermore, the results clearly showed that the sPSU membrane induced mass-transport limitations in both sPSU and Nafion GDEs, revealing that the limiting factor of the sPSU MEAs was primarily the membrane-induced cathode flooding due to unoptimized water transport in the sPSU membrane. The work demonstrates the importance of electrochemical evaluation of ionomers as complete MEAs and as separate components when studying MEAs.

  • 272.
    von Kraemer, Sophie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Puchner, Mario
    Division of Polymer and Materials Chemistry, Lund University.
    Jannasch, Patric
    Division of Polymer and Materials Chemistry, Lund University.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Erratum: Gas Diffusion Electrodes and Membrane Electrode Assemblies Based on a Sulfonated Polysulfone for High-Temperature PEMFC [J. Electrochem. Soc., 153, A2077 (2006)]2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 12, p. L35-L35Article in journal (Refereed)
  • 273.
    von Kraemer, Sophie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Puchner, Mario
    Division of Polymer and Materials Chemistry, Lund University.
    Jannasch, Patric
    Division of Polymer and Materials Chemistry, Lund University.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Gas Diffusion Electrodes and Membrane Electrode Assemblies Based on a Sulfonated Polysulfone for High-Temperature PEMFC2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 11, p. A2077-A2084Article in journal (Refereed)
    Abstract [en]

    Membrane electrode assemblies MEAs with a sulfonated polysulfone sPSU as the proton-conducting phase were fuel cellevaluated at varying temperatures in over-humidified conditions. The sPSU was prepared by a direct polycondensation involvinga commercially available sulfonated naphthalene diol monomer. The gas diffusion electrodes GDEs and MEAs were successfullyfabricated and a thorough morphological study was subsequently carried out on GDEs with varying sPSU contents and inksolvents. The scanning electron microscopy and porosimetry studies revealed highly porous GDE morphologies at sPSU contentsbelow 20 wt %. Double-layer capacitance measurements showed an almost fully sPSU-wetted electronic phase when the sPSUcontent was 10 wt %. The MEAs were prepared by applying the GDEs directly onto sPSU membranes. MEAs with a total Ptloading of 0.2 mg/cm2 were successfully fuel cell operated at 120°C. The MEAs showed mass-transport limitations in the rangeof 600–800 mA/cm2, most probably caused by abundant water due to the overhumidified measuring conditions. The low resistanceof the MEAs indicated a well-integrated structure between the GDEs and the membrane.

  • 274. Wallinder, D.
    et al.
    Hornlund, E.
    Hultquist, Gunnar
    KTH, Superseded Departments, Materials Science and Engineering.
    Influence of hydrogen in iron and in two stainless steels on aqueous and gaseous corrosion2002In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 149, no 9, p. B393-B397Article in journal (Refereed)
    Abstract [en]

    The influence of hydrogen in Fe, 301 stainless steel (SS 301), and Avesta 353MA on corrosion resistance in aqueous solutions was studied. The oxidation kinetics of uncoated and Pt-coated Fe was also investigated in O-2 at 500 and 700degreesC. Electrochemical and weight loss measurements were used to evaluate the corrosion resistance in aqueous solutions, and the high-temperature oxidation rate was determined by measuring the pressure decrease in a closed volume. Observations of a high dissolution rate of Fe and SS 301 in deionized water, as well as a high oxidation rate in O-2, can be explained by an increased metal cation transport in the oxide film induced by hydrogen in the metal. However, hydrogen up to a certain concentration in Avesta 353MA was found to increase the resistance to localized corrosion in chloride solution. Pt coating on Fe was found to decrease the oxidation rate and improve scale adherence. The presented results are discussed in view of recent findings of balanced metal cation and oxygen anion transport in protective metal oxides.

  • 275. Wang, Yongchao
    et al.
    Yin, Litao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. University of Science and Technology Beijing, China.
    Jin, Ying
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Numerical Simulation of Micro-Galvanic Corrosion in Al Alloys: Steric Hindrance Effect of Corrosion Product2018In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 14, p. C1035-C1043Article in journal (Refereed)
    Abstract [en]

    An improved finite element model was established to demonstrate the steric hindrance effect of the precipitated corrosion product (Al(OH)(3)) on micro-galvanic corrosion triggered by intermetallic particles (IMPs) in an Al-matrix. In this model, the precipitation/ dissolution of the corrosion product could occur in the whole liquid field as the result of a reversible reaction. Simulation results show that the precipitated insulating Al(OH)(3) on the electrode surface can inhibit further corrosion by reducing the conductivity of the solution and the active electrode surface area. Meanwhile, the steric hindrance effect of the precipitated Al(OH)(3) also slows down the diffusion and migration of species in the solution. Moreover, considering the porous nature of precipitated Al(OH)(3), a porosity parameter epsilon was introduced to describe the degree of compactness of corrosion product, which reaches a certain minimum value epsilon(c) under a specific corrosion situation. Compared to the previous work in which a surface coverage parameter was used to describe the blocking effect of Al(OH)(3) on surface activity, the present model is more realistic in mimicking the micro-galvanic corrosion, and also useful for the simulation of the transition from metastable pit formation to pit propagation.

  • 276.
    Warczak, Magdalena
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Univ Warsaw, Poland.
    Osial, Magdalena
    Univ Warsaw, Poland.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Glowacki, Eric
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering. Warsaw Univ Technol, Poland.
    Electrogeneration of Hydrogen Peroxide via Oxygen Reduction on Polyindole Films2020In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 167, no 8, article id 086502Article in journal (Refereed)
    Abstract [en]

    Efficient electrochemical generation of hydrogen peroxide via oxygen reduction is of great interest for industrial and clean energy applications. In this work, we report the application of conducting polymer-polyindole (PIN) films for electrogeneration of hydrogen peroxide. Polyindole films were electrochemically polymerized on gold substrates in non-aqueous electrolytes and then tested for electrocatalytic properties in acidic aqueous solutions. We find that PIN can serve as an electrocatalyst for oxygen reduction reaction via a two-electron pathway. Electrolysis performance indicates that PIN is an efficient, selective, and stable electrocatalyst for hydrogen peroxide generation at low pH, and suggests PIN as a conducting polymer with useful electrocatalytic properties in scientific experiments and applications. (C) 2020 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.

  • 277.
    Weissenrieder, Jonas
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Kleber, C.
    Schreiner, M.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    In situ studies of sulfate nest formation on iron2004In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 151, no 9, p. B497-B504Article in journal (Refereed)
    Abstract [en]

    Initial SO2-induced atmospheric corrosion of iron has been followed in situ by three highly surface sensitive and complementary techniques, infrared reflection absorption spectroscopy, quartz crystal microbalance, and atomic force microscopy. The resulting corrosion attack was local in nature and resembled what are called sulfate nests, frequently observed on steel naturally exposed outdoors. The conclusions drawn challenge the established model for the formation and growth of sulfate nests: SO2 alone in humid air is not a sufficient prerequisite for sulfate nest formation. Only when an oxidant such as NO2 or O-3 is added to the corrosive atmosphere, can sulfate nests be detected. The conditions and formation of sulfate nests and other forms of local corrosion attacks are discussed in view of all in situ observations generated.

  • 278.
    Weissenrieder, Jonas
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    In situ studies of filiform corrosion of iron2004In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 151, no 3, p. B165-B171Article in journal (Refereed)
    Abstract [en]

    The influence of small amounts (similar to2 mug/cm(2)) of deposited NaCl on the initial atmospheric corrosion of iron has been investigated in situ at varying relative humidities. The deliquescence of the NaCl crystallites and corrosion product formation was followed at relative humidities >75% with quartz crystal microbalance combined with either infrared reflection absorption spectroscopy or optical microscopy. The resulting corrosion attacks initiate at droplets of NaCl solution and form filaments characteristic of filiform corrosion. During the progress of filiform corrosion specific features observed include a constant mass increase rate with time at a given relative humidity, a NaCl-depleted radial zone in front of the active filament head, a chlorine-enriched filament head, and a step-wise growth of the filament. The chloride transport towards the filament head is believed to be mass-transport limited and the filament growth is driven by a differential aeration cell within the filament.

  • 279.
    Wen, Rui-Tao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromic Iridium-Containing Nickel Oxide Films with Excellent Electrochemical Cycling Performance2016In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 163, no 2, p. E7-E13Article in journal (Refereed)
    Abstract [en]

    Electrochromic Ni oxide thin films attract much interest because of their large potential for applications as optically active layers in energy-saving and comfort enhancing smart windows in buildings. However Ni oxide, typically being the anodic counter electrode in a W-oxide-based device, may suffer severe charge capacity degradation upon extended electrochemical cycling. It is therefore important to identify improved Ni-oxide-based thin films for electrochromics. Here we describe a new class of such films wherein an addition of a small amount of Ir to Ni oxide is found to provide strongly improved electrochemical cycling durability. Best properties were achieved with Ir/(Ir + Ni) = 7.6%, and such films displayed charge capacity and optical modulation that, remarkably, were still increasing after 10,000 cycles.

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  • 280.
    Wesselmark, Maria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lagergren, Carina
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Methanol oxidation as anode reaction in zinc electrowinning2005In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 152, no 11, p. D201-D207Article in journal (Refereed)
    Abstract [en]

    In this study, different types of Pt- and PtRu-based electrodes were compared regarding their activity and stability for methanol oxidation in an acid zinc sulfate solution. The lead anodes used in zinc electrowinning today are not dimensionally stable and have a high overvoltage for oxygen evolution. By replacing the oxygen evolution in sulfate-based electrolytes with methanol oxidation, the anode potential could be significantly lowered. This would reduce the energy consumption and also enable the use of new and more stable types of electrodes. The activities of the electrodes studied were found sufficient for electrowinning. The highest activity was obtained with porous PtRu, while platinized titanium was the most stable electrode. All electrodes were deactivated with time, and the deactivation rate of PtRu was influenced by mass transport. The dominating reaction mechanism seemed to be different on Pt and on PtRu. Due to deactivation of the electrodes with time, a reactivation method was needed. The best method tested in this study was to periodically reverse the current. After assessing the electrodes with respect to important properties, the platinized titanium electrode was considered to be most suitable for use in electrowinning processes.

  • 281.
    Wiezell, Katarina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Holmström, Nicklas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Studying Low-Humidity Effects in PEFCs Using EIS II: Modeling2012In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 159, no 8, p. F379-F392Article in journal (Refereed)
    Abstract [en]

    Electrochemical impedance spectroscopy (EIS) and steady-state models have been developed to investigate the influence of water transport on the membrane and electrode performance, with focus on the low-frequency impedance. Models for the membrane, hydrogen anode and oxygen cathode were connected in order to take the influence of water concentration on proton conductivity and hydrogen kinetics into account. At low frequencies, below 1 Hz, a pseudo-inductive loop was predicted, resulting from the overlap of the responses from anode and membrane. The anode response could be coupled to changes in the kinetics and polymer conductivity in the active layer, and the membrane response to changes in conductivity with changing water profile. The low frequency capacitive part was attributed to drying of the anode side of the membrane, while the inductive part was attributed to the rehydration of the membrane with water produced at the cathode. The loop appeared at a frequency proportional to 1/L-2, where L is the membrane thickness. The model was successfully fitted to experimental data at different membrane thicknesses, relative humidities and current densities. The modeled data follow the same trends as experimental data, giving an increase in impedance at dry conditions and with thicker membranes.

  • 282.
    Wiezell, Katarina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Gode, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Steady-State and EIS Investigations of Hydrogen Electrodes and Membranes in Polymer Electrolyte Fuel Cells: I. Modeling2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 4, p. A749-A758Article in journal (Refereed)
    Abstract [en]

    Electrochemical impedance spectroscopy (EIS) and steady-state models have been developed for the porous hydrogen electrode with water concentration dependence and water transport in a polymer electrolyte fuel cell membrane. Because the hydrogen electrode performance is influenced by its water content, the hydrogen electrode model was coupled to the membrane model. The EIS model for the hydrogen electrode gave three to four loops in the complex plane plots. The high-frequency semicircle was attributed to the Volmer reaction and the medium-frequency semicircle to the hydrogen adsorption. The additional low-frequency loops were connected to changes in the hydrogen electrode performance with water concentration, due to changes in kinetics or proton conductivity. Those loops appear in a frequency range depending on the water transport in the membrane, changing with D/L-m(2), where D is the water diffusivity and L-m is the membrane thickness. Modeling of the membrane alone showed that the membrane gives rise to a loop in EIS. The difference between the high- and low-frequency intercepts of the loop is idR/di, where the high-frequency intercept is equal to the membrane resistance. The loop appears in the same frequency range as the hydrogen electrode low-frequency loops and thus overlaps.

  • 283.
    Wiezell, Katarina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Gode, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Steady-state and EIS investigations of hydrogen electrodes and membranes in polymer electrolyte fuel cells: II. Experimental2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 4, p. A759-A764Article in journal (Refereed)
    Abstract [en]

    Influence of water on membrane and anode performance was studied with steady-state and electrochemical impedance spectroscopy (EIS) measurements using a symmetrical cell with hydrogen on both sides. Both full-cell and half-cell measurements were performed. To obtain half-cell data a new reference electrode approach was demonstrated based on porous references in a four-electrode setup. A varying membrane resistance with current density was obtained using current interrupt and EIS measurements. The EIS measurements showed two semicircles at 10(4) Hz and 0.01-0.1 Hz, respectively. The first corresponds to hydrogen adsorption and the second to the water dependence of the electrode performance and membrane resistance. The low-frequency semicircle appears in a frequency range depending on the membrane thickness. The loop corresponding to the discharge of the double-layer capacitance through the Volmer reaction appears at frequencies too high to be experimentally measurable. The experimental data were in good agreement with the model developed in Part I of this paper. The model was also successfully fitted to experimental full cell data at different current densities and membrane thicknesses. The experiments confirmed that the low-frequency semicircle is attributed to the water dependence of both anode and membrane performance.

  • 284.
    Wijaya, Olivia
    et al.
    TUM CREATE, Singapore 138602, Singapore.; Nanyang Technol Univ, Sch Mat Sci & Engn, Singapore 639798, Singapore.
    Rinaldi, Ali
    TUM CREATE, Singapore 138602, Singapore.; King Fahd Univ Petr & Minerals, Dept Chem, Dhahran 31261, Saudi Arabia.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Yazami, Rachid
    TUM CREATE, Singapore 138602, Singapore.; Nanyang Technol Univ, Sch Mat Sci & Engn, Singapore 639798, Singapore.; Nanyang Technol Univ, Energy Res Inst, Singapore 637141, Singapore.
    The Origin of Li-O2 Battery Performance Enhancement Using Fluorocarbon Additive2016In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 163, no 13, p. A2660-A2664Article in journal (Refereed)
    Abstract [en]

    Perfluorocarbon compounds (PFC) are known for their high O2 dissolution capability and have been investigated as additives/electrolyte solvents to improve Li-O2 batteries performance. Nevertheless, systematic studies that go beyond the proof of concept that fluorocarbon additives enhance the performance of Li-O2 batteries have not been carried out yet. In this work, we investigate 1-methoxyheptafluoropropane additive (1-PFC), a fluorocarbon with an ether functional group that has been considered as one of the candidates as additives in the Li-O2 battery. Using electrochemical methods and physical characterization of discharge products, we found that the enhancement of the discharge capacity of Li-O2 cells with 1-PFC additive is most likely correlated with instability of the 1-PFC additive against superoxide radicals, rather than the improvement in O2 solubility.

  • 285. Wijayasinghe, A.
    et al.
    Bergman, Bill
    KTH, Superseded Departments, Materials Science and Engineering.
    Lagergren, Carina
    KTH, Superseded Departments, Chemical Engineering and Technology.
    LiFeO2-LiCoO2-NiO cathodes for molten carbonate fuel cells2003In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, no 5, p. A558-A564Article in journal (Refereed)
    Abstract [en]

    Dissolution of the state-of-the-art lithiated nickel oxide cathode is a major obstacle for the development of molten carbonate fuel cell (MCFC) technology. LiFeO2 and LiCoO2 were reported earlier as the most promising alternative materials; however, they do not satisfactorily substitute for the state-of-the-art cathode material. A solid solution consisting of LiFeO2, LiCoO2, and NiO is expected to posses some desirable properties of these three materials. Powder compositions in the LiFeO2-NiO binary system and a ternary subsystem with a constant 50:50 molar ratio of LiFeO2:NiO were prepared by the Pechini method. After preliminary powder characterizations, the feasibility of new materials for MCFC cathode application was studied. Electrical conductivity and microstructural characteristics were investigated, first in the form of bulk pellets and then in ex situ sintered porous gas diffusion cathodes. Finally, the electrochemical performance of selected cathodes was evaluated by short-time laboratory scale cell operations. The electrical conductivity of the ternary compositions with 50:50 molar ratio of LiFeO2:NiO increases significantly with increasing LiCoO2 content up to about 25 mol %. Further increase of LiCoO2 content decreases conductivity. The cell study indicates the possibility of preparing cathodes suitable for MCFC application with a considerably high LiFeO2 content.

  • 286.
    Wreland Lindström, Rakel
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Kortsdottir, Katrin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Wesselmark, Maria
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Oyarce, Alejandro
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lagergren, Carina
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Active Area Determination of Porous Pt Electrodes Used in Polymer Electrolyte Fuel Cells: Temperature and Humidity Effects2010In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 157, no 12, p. B1795-B1801Article in journal (Refereed)
    Abstract [en]

    This paper discusses the proper measure of the electrochemically active area (ECA)of carbon supported Pt catalyst in PEM fuel cells employing in situ cyclic voltammetry. The charges of the hydrogen underpotential deposition (Hupd) and CO stripping peak obtained in situ are compared, and the influence of operation temperature (25–80°C) and relative humidity (40%–90%) is discussed. The results show that the charges of the Hupd decrease with rising temperature, while the corresponding charges of the CO stripping peak are essentially independent of temperature, at least at high relative humidity. The unexpectedly small Hupd charges are explained by the significant overlap with the hydrogen evolution reaction in a fuel cell at elevated temperatures. According to our results, it is proposed that a more reliable value of Pt ECA is estimated from the CO stripping charge. However, with decreasing humidity the charges of both Hupd and CO stripping peaks decrease, which is probably an effect of increasing blockage of Pt active sites by hydrophobic domains in the electrode ionomer. Some implications of varying cell conditions on the estimated Pt ECA and its correlation with fuel cell activity are discussed in an example from a fuel cell degradation test.

  • 287.
    Wreland Lindström, Rakel
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Oyarce, Alejandro
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Aguinaga, Luis Guerrero
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Ubeda, Diego
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Ingratta, Mark
    Jannasch, Patric
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Performance of Phosphonated Hydrocarbon Ionomer in the Fuel Cell Cathode Catalyst Layer2013In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 160, no 3, p. F269-F277Article in journal (Refereed)
    Abstract [en]

    Inexpensive and environmentally friendly electrolyte polymers that can be operated at higher temperatures and drier conditions are highly interesting for PEM fuel cells for automotive, portable power and stationary electricity generation applications. In this study an ionomer based on polysulfone grafted with poly(vinylphosphonic acid) (PSUgPVPA) in the cathode Pt/C catalyst layer was electrochemically characterized and compared to Nafion. The performance at different levels of humidity at 80 degrees C was evaluated by polarization measurements, cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The results show that the performance of the PSUgPVPA-based cathode catalyst layer is comparable to that of Nafion-at 100% relative humidity (RH) but with some instabilities. However, at drier conditions significant losses of performance for the PSUgPVPA-based cathode was observed. This could be an effect of catalyst poisoning by the ionomer interfering with ORR. However, the concomitant decrease of the electrochemical surface area, double layer capacitance and increased imaginary impedance, indicate that the poorer performance at low humidity is mainly an effect of reduced catalyst wetting by the ionomer in combination with the decreased proton conduction in the ionomeric phase.

  • 288.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Jeschull, Fabian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brant, William R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    The Role of LiTDI Additive in LiNi1/3Mn1/3Co1/3O2/ Graphite Lithium-Ion Batteries at Elevated Temperatures2018In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 165, no 2, p. A40-A46Article in journal (Refereed)
    Abstract [en]

    The poor thermal stability of conventional LiPF6-based electrolytes is one of the major obstacles for today's lithium-ion batteries. Recently, lithium 4,5-dicyano-2-( trifluoromethyl) imidazolide (LiTDI) has demonstrated to be highly efficient in scavenging moisture from the electrolyte and thereby improving electrolyte stability. In this context, effects of the LiTDI additive on LiNi1/3Mn1/3Co1/3O2 (NMC)/graphite cells are evaluated at a temperature of 55 degrees C. With the incorporation of LiTDI, an improved cycling performance of NMC/graphite cells was achieved, and the impedance increase at the NMC/electrolyte interface was significantly mitigated. Furthermore, LiTDI exhibited a profound influence on the interfacial chemistries in the full cell, and LiTDI-derived species were found on the surfaces of both the cathode and the anode. The SEI layer formed on graphite anodes was more homogenous in morphology and consisted of larger amounts of LiF and fewer oxygen-containing species, as compared to graphite in additive-free cells. This study shows that LiTDI is a promising electrolyte additive for NMC/graphite cells operated at elevated temperatures, highlighting that the influence of the LiTDI additive is worth exploring also in other battery chemistries.

  • 289.
    Yin, Litao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Univ Sci & Technol Beijing, Peoples R China.
    Jin, Ying
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Birbilis, Nick
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Numerical Simulation of Micro-Galvanic Corrosion in Al Alloys: Effect of Geometric Factors2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 2, p. C75-C84Article in journal (Refereed)
    Abstract [en]

    A finite element model for simulating the propagation of intermetallic particle driven micro-galvanic corrosion in an Al-matrix model system is presented. The model revealed dynamic changes related to localized corrosion, including the moving dissolution boundary, the deposition of reaction products (Al(OH)(3)), and their blocking effect. Modelling was focused on the effects of key geometric parameters, including the radius of cathodic particle (range 0.5 to 4 mu m) and the width of an assumed anodic ring surrounding the particle (range 0.1 to 2 mu m). Simulations revealed the dynamic flow of molecular and ionic species, along with influence of geometrical constraints. For ring widths below 0.5 mu m, deposition of Al(OH)(3) inside the dissolving volume was inhibited due to limited transport of OH- and O-2 into a constrained volume - resulting in local acidification. An increase in cathodic particle radius at given ring width resulted in a greater dissolution by providing a larger cathodic area for O-2 reduction, quantifying the effect of cathode/anode ratio. The model was also developed to include two cathodic particles to explore any interaction. The present study reveals a physicochemical model that contributes toward a framework for multi-process localized corrosion systems, which can be further adapted to commercial alloy systems.

  • 290.
    Yin, Litao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. University of Science and Technology Beijing, China.
    Jin, Ying
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Numerical Simulation of Micro-Galvanic Corrosion of Al Alloys: Effect of Chemical Factors2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 13, p. C768-C778Article in journal (Refereed)
    Abstract [en]

    A finite element model for simulating the propagation of micro-galvanic corrosion of Al alloys induced by intermetallic particle was established to reveal the dynamic changes including a moving dissolution boundary, deposition of reaction products and their blocking effect. This model has previously been used to study the influence of geometrical factors such as the particle size and width of the anodic ring. In this work, we explore effects of chemical factors including pH and bulk concentration of O-2 by using chemical-dependent electrochemical kinetics as input parameters. The simulations reveal that the micro-galvanic corrosion rate is slowest at pH = 6. For pH > 6, the rise of pH increases the dissolution rate of Al and also the deposition rate of Al(OH)(3), leading to a faster but more short localized Al dissolution. For pH < 6, the decline of pH accelerates Al dissolution and inhibits Al(OH)(3) deposition, leading to a faster and more long lasting Al dissolution. At pH <= 4, deposition of Al(OH)(3) becomes negligible, and localized corrosion will propagate continuously. Within the O-2 concentration range relevant for atmospheric conditions, a lower O-2 concentration in the solution leads to a slower rate of micro-galvanic corrosion.

  • 291.
    Yin, Litao
    et al.
    Univ Sci & Technol Beijing, Natl Ctr Mat Serv Safety, Beijing 100083, Peoples R China.;KTH Royal Inst Technol, Sch Engn Sci Chem Biotechnol & Hlth, Dept Chem, Div Surface & Corros Sci, SE-10044 Stockholm, Sweden..
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Jin, Ying
    Univ Sci & Technol Beijing, Natl Ctr Mat Serv Safety, Beijing 100083, Peoples R China..
    Experimental and Simulation Investigations of Copper Reduction Mechanism with and without Addition of SPS2018In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 165, no 13, p. D604-D611Article in journal (Refereed)
    Abstract [en]

    Rotating disk electrode and rotating ring-disk electrode were used to investigate the mechanism of copper reduction and the influence of convection on the effect of Bis-3-sodiumsulfopropyl disulfide (SPS), a widely used accelerator in copper via-filling and copper foil manufacturing. The experimental results show that the commonly accepted single electron transfer for copper reduction is dominating in the low overpotential range, whereas the double electron transfer is also involved in the high overpotential range. SPS was found to exhibit a weak inhibition effect even with Cl- ion in the solution under strong convection, and generate more intermediates in the solution with both Cl- ion and SPS than with Cl- ion alone. Based on the experimental observations, a reaction model for copper reduction considering competition between the single electron transfer and the double electron transfer, as well as desorption and runoff of generated Cu+-containing intermediates, was proposed and used for finite element method modeling. The simulation results enable quantitative description of the proportion of the two charge transfer reactions and the runoff of the intermediates, providing guidelines for selecting the additives and plating conditions in industrial manufacturing. 

  • 292.
    Younesi, Reza
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Christiansen, Ane Sælland
    Technical University of Denmark.
    Scipioni, Roberto
    Technical University of Denmark.
    Ngo, Duc-The
    Technical University of Denmark.
    Simonsen, Søren Bredmose
    Technical University of Denmark.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hjelm, Johan
    Technical University of Denmark.
    Norby, Poul
    Technical University of Denmark.
    Analysis of the Interphase on Carbon Black Formed in High Voltage Batteries2015In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 162, no 7, p. A1289-A1296Article in journal (Refereed)
    Abstract [en]

    Carbon black (CB) additives commonly used to increase the electrical conductivity of electrodes in Li-ion batteries are generally believed to be electrochemically inert additives in cathodes. Decomposition of electrolyte in the surface region of CB in Li-ion cells at high voltages up to 4.9 V is here studied using electrochemical measurements as well as structural and surface characterizations. LiPF6 and LiClO4 dissolved in ethylene carbonate:diethylene carbonate (1:1) were used as the electrolyte to study irreversible charge capacity of CB cathodes when cycled between 4.9 V and 2.5 V. Synchrotron-based soft X-ray photoelectron spectroscopy (SOXPES) results revealed spontaneous partial decomposition of the electrolytes on the CB electrode, without applying external current or voltage. Depth profile analysis of the electrolyte/cathode interphase indicated that the concentration of decomposed species is highest at the outermost surface of the CB. It is concluded that carboxylate and carbonate bonds (originating from solvent decomposition) and LiF (when LiPF6 was used) take part in the formation of the decomposed species. Electrochemical impedance spectroscopy measurements and transmission electron microscopy results, however, did not show formation of a dense surface layer on CB particles.

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  • 293.
    Zangooie, S.
    et al.
    Ctr. Microlectron. Optical Mat. Res., Department of Electrical Engineering, University of Nebraska, Lincoln, NE 68588-0511, United States.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Surface, Pore Morphology, and Optical Properties of Porous 4H-SiC2001In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 148, no 6Article in journal (Refereed)
    Abstract [en]

    Electron microscopy and spectroscopic ellipsometry are used to investigate the microstructural and optical properties of porous SiC. It is discussed that lc dislocations are likely to play a role in the initial phases of the anodization process in terms of formation of nanometer sized holes. Pores are found to initially propagate nearly parallel with the sample surface and gradually change direction toward the c axis. Pore sizes are found to increase with depth toward the interface between the porous SiC and the substrate. A different pore morphology is found along the internal surfaces of micropipes, where structures are relatively large in size and appear spherical in shape. The anisotropy in pore propagation influences the etch rate, which varies in a nonlinear manner with the anodization time. The etching rate is also influenced by the larger absorptivity of the porous layers caused by formation of a disordered phase at the interface between the crystalline SiC and the pores. Ellipsometric analysis of porous SiC layers yields thicknesses and porosities in good agreement with the electron microscopy observations. Optical properties of the solid content of the porous layers are significantly different from those of hulk crystalline SiC, and depend on the etching time and sample thickness. © 2001 The Electrochemical Society. [DOI: 10.1149/1.1368109] All rights reserved.

  • 294.
    Zavalis, Tommy Georgios
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Behm, Mårten
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Investigation of Short-Circuit Scenarios in a Lithium-Ion Battery Cell2012In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 159, no 6, p. A848-A859Article in journal (Refereed)
    Abstract [en]

    A short-circuited lithium-ion battery cell is likely to generate sufficient heat to initiate exothermic side reactions causing thermal runaway. A 2D coupled electrochemical-thermal model was developed to investigate a prismatic LiNi0.8Co0.15Al0.05O2 vertical bar LiPF6, EC/EMC (3:7)vertical bar MAG-10 battery cell that is short-circuited. Three short-circuit scenarios are investigated during the events from when short circuit occurs until exothermic side reactions initiate. The scenarios are an external short circuit, a nail penetration and an impurity-induced short circuit. The model is used to predict the temperature increase within the cell and to explain how the interrelation between the electrochemical processes and the thermal properties affects the increase. Important safety measures are also examined with the model. The simulation results highlight general short-circuit characteristics and critical distinctions between the scenarios. The mass transport of lithium ions in the electrolyte is found to be the most important general characteristic that determines the rate of the temperature increase. The electric resistance distinguishes the scenarios from each other. The rate of the temperature increase is dictated by the mass transport in the electrolyte even when large variations in available active material are made and it is shown to be difficult to slow down the rate by cooling.

  • 295.
    Zhang, Fan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nilsson, J. -O
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    In situ and operando AFM and EIS studies of anodization of Al 6060: Influence of intermetallic particles2016In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 163, no 9, p. C609-C618Article in journal (Refereed)
    Abstract [en]

    In this study, anodization of an Al 6060 alloy has been investigated by in-situ electrochemical atomic force microscopy (EC-AFM) and electrochemical impedance spectroscopy (EIS) under operando conditions, to elucidate the role of intermetallic particles (IMPs) in the alloy. The Volta potential maps measured by scanning Kelvin probe force microscopy (SKPFM) reveal that the relative nobility is higher for AlFeSi type and lower for Mg2 Si type of particles as compared with the alloy matrix. The EIS results obtained at anodizing potentials show that the thickness of the barrier oxide layer increases linearly with the applied potential, but the oxide growth rate is lower than that of single crystal samples reported previously. Moreover, the EIS spectra show an inductive loop at low frequencies indicating an anodic dissolution process. The EC-AFM images display detailed morphological changes related to the IMPs during the anodization, which reveal certain localized dissolution in parallel to anodic Al oxide (AAO) formation on the alloy. The combined AFM and EIS measurements demonstrate that the IMPs in the alloy cause localized dissolution during anodization, resulting in a reduced AAO growth rate. The corrosion resistance of as-produced AAO film is low unless anodized at sufficiently high potential.

  • 296.
    Zhao, Weijie
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Johnson, C. Magnus
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Nano Infrared Microscopy: Obtaining Chemical Information on the Nanoscale in Corrosion Studies2019In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, no 11, p. C3456-C3460Article in journal (Refereed)
    Abstract [en]

    In this perspective article, the novel technique "nano infrared microscopy" is introduced as a valuable tool in the field of corrosion science to obtain chemical information with a spatial resolution of around 10 nm. Accordingly, the resolution is well below the diffraction limit, in contrast to conventional vibrational microscopy techniques. Thus, studies of corrosion initiation, localized corrosion, and thin protective films can be performed in greater detail than before. There are a few different types of nano infrared microscopes, but they all have in common that they are based on a combination of infrared (IR) spectroscopy and atomic force microscopy (AFM). In this article the theory of the different techniques is discussed, and some results are highlighted to show the ability of the technique in the field of corrosion science. Future possibilities of the technique in studies of corrosion and degradation of materials are also discussed. 

  • 297.
    Zhu, Baiwei
    et al.
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Fedel, Michele
    Department of Industrial Engineering, University of Trento, Trento, Italy.
    Andersson, Nils-Eric
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Leisner, Peter
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing. SP-Technical Research Institute of Sweden, Borås, Sweden.
    Deflorian, Flavio
    Department of Industrial Engineering, University of Trento, Trento, Italy.
    Zanella, Caterina
    Jönköping University, School of Engineering, JTH, Materials and Manufacturing.
    Effect of Si content and morphology on corrosion resistance of anodized cast Al-Si alloys2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 7, p. C435-C441Article in journal (Refereed)
    Abstract [en]

    This paper investigates the influence of Si content and Si particle morphology on the corrosion protection of anodized oxide layers on Al-Si alloys. Two Al alloys with low Si concentrations (2.43 wt-% and 5.45 wt-%, respectively) were studied and compared with 6082-T6 via electrochemical impedance spectroscopy (EIS) in 3 wt-% NaCl solution prior to oxide layer sealing. Si particles were also modified by the addition of Sr to study the influence of Si particle morphology on the corrosion protection of the oxide layer. The EIS showed that the corrosion protection provided by the oxide layer on Al-Si alloys is significantly affected by the presence of Si particles. Si particles make the oxide layer locally thinner and more defective in the eutectic region, thereby increasing the ease of substrate corrosion attack. However, the addition of Sr can improve the corrosion protection of anodized Al-Si alloys significantly. Furthermore, it was proved that higher Si level influences negatively the anodized oxide corrosion protection due to the higher amount of cracks and defects, but Sr modification is efficient in preventing this negative effect.

  • 298.
    Zhu, Baiwei
    et al.
    Jönköping University, Sweden.
    Fedel, Michele
    University of Trento, Italy.
    Andersson, Nils-Eric
    Jönköping University, Sweden.
    Leisner, Peter
    RISE - Research Institutes of Sweden, Safety and Transport, Electronics. Jönköping University, Sweden.
    Deflorian, Flavio
    University of Trento, Italy.
    Zanella, Caterina
    Jönköping University, Sweden.
    Effect of Si content and morphology on corrosionresistance of anodized cast Al-Si alloys2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 7, p. C435-C441Article in journal (Refereed)
    Abstract [en]

    This paper investigates the influence of Si content and Si particle morphology on the corrosion protection of anodized oxide layers on Al-Si alloys. Two Al alloys with low Si concentrations (2.43 wt-% and 5.45 wt-%, respectively) were studied and compared with 6082-T6 via electrochemical impedance spectroscopy (EIS) in 3 wt-% NaCl solution prior to oxide layer sealing. Si particles were also modified by the addition of Sr to study the influence of Si particle morphology on the corrosion protection of the oxide layer. The EIS showed that the corrosion protection provided by the oxide layer on Al-Si alloys is significantly affected by the presence of Si particles. Si particles make the oxide layer locally thinner and more defective in the eutectic region, thereby increasing the ease of substrate corrosion attack. However, the addition of Sr can improve the corrosion protection of anodized Al-Si alloys significantly. Furthermore, it was proved that higher Si level influences negatively the anodized oxide corrosion protection due to the higher amount of cracks and defects, but Sr modification is efficient in preventing this negative effect.

  • 299.
    Zuleta, Marcelo
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Björnbom, Pehr
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Characterization of the electrochemical and ion-transport properties of a nanoporous carbon at negative polarization by the single-particle method2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 1, p. A48-A57Article in journal (Refereed)
    Abstract [en]

    In this work, the electrochemical processes occurring in a nanoporous carbon, obtained from silicon carbide and used as negative electrode material for supercapacitors, have been investigated by means of the single-particle microelectrode method. The processes studied deal with hydrogen adsorption, evolution, and oxidation using 6 M KOH as electrolyte. It was found that adsorption of hydrogen started at -0.5 V, hydrogen evolution at -1.4 V vs Hg vertical bar HgO, and that hydrogen oxidation occurs in two steps. The first oxidation process takes place between 0 and 0.1 V, shown by a well-defined current peak on the voltammograms. The second oxidation stage occurs between 0.1 and 0.5 V, indicated by a successive increase in current with the number of cycles. It was also found that after the first oxidation process, subsequent cycling between -0.5 and -1 V leads to a larger accumulation of hydrogen inside the nanopores and to a decrease of the effective diffusion coefficient (D-eff) of potassium ions. Subsequent oxidation, in a second process, leads to a total consumption of hydrogen and to an increase of D-eff.

  • 300.
    Zuleta, Marcelo
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Björnbom, Pehr
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Effects of pore surface oxidation on electrochemical and mass-transport properties of nanoporous carbon2005In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 152, no 2, p. A270-A276Article in journal (Refereed)
    Abstract [en]

    A new nanoporous (NP) carbon material with a high surface area and a narrow pore size distribution, around 8 A, has been used to investigate the effects that electrochemical oxidation at positive potentials exerts on the capacitance values and effective diffusion coefficients of ions inside the nanopores. An electroanalytical method, based on the single-particle microelectrode technique with micromanipulator, was applied to calculate the diffusion coefficients of 6 M KOH ions in NP carbon. The results were analyzed for short times using the Cottrell model and for long times using the spherical diffusion model. Using cyclic voltammetry, was found that different stages of oxidation took place between 0 and 0.5 V vs. Hg\HgO. After repeated cycling in the first region of oxidation (0-0.3 V), an activation leading to higher capacitance was observed, but the diffusion coefficients decreased from approximately 2 x 10(-9) to 0.5 x 10(-10) cm(2) s(-1). In the second region of oxidation (0.3-0.5 V), where CO2 and 02 evolution can occur, both the capacitance and the diffusion coefficients decreased more dramatically. The effective diffusion coefficients of ions of an activated carbon particle were dependent on the operation potential; decreasing by an order of magnitude when going from -0.3 to +0.3 V. The results are discussed in terms of chemisorption of small oxygen functional groups (-OH or C=O) and ionic interaction with the pore wall.

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