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  • 1.
    Adhikari, Arindam
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Pani, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Deidinaitei, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Electrochemical behavior and anticorrosion properties of modified polyaniline dispersed in polyvinylacetate coating on carbon steel2008In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, no 12, 4239-4247 p.Article in journal (Refereed)
    Abstract [en]

    Conducting polyaniline (Pani) was prepared in the presence of methane sulfonic acid (MeSA) as dopant by chemical oxidative polymerization. The Pani-MeSA polymer was characterized by FT-IR, UV-vis, X-ray diffraction (XRD) and impedance spectroscopy. The polyrner was dispersed in polyvinylacetate and coated oil carbon steel samples by a dipping method. The electrochemical behavior and anticorrosion properties of the coating, oil carbon steel in 3% NaCl were investigated using Open-circuit Potential (OCP) versus time of exposure, and electrochemical techniques including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and cyclic voltammetry (CV). During initial exposure, the OCP dropped about 0.35 V and the interfacial resistance increased several times, indicating I certain reduction of the polymer and oxidation of the steel surface. Later the OCP shifted to the noble direction and remained at a stable value during the exposure up to 60 days. The EIS monitoring also revealed the initial change and later stabilization of the coating. The stable high OCP and low coating impedance Suggest that the conducting polymer maintains its oxidative state and provides corrosion protection for carbon steel through out the investigated period. The polarization curves and CV show that the conducting polymer coating induces a passive-like behavior and greatly reduces the corrosion of carbon steel.

  • 2.
    Afzal, Muhammad
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Raza, R.
    Du, S.
    Lima, R.B.d
    Zhu, Bin
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics. Hubei Univ, Fac Phys & Elect Technol, Hubei Collaborat Innovat Ctr Adv Organ Chem Mat, Wuhan 430062, Peoples R China.
    Synthesis of Ba0.3Ca0.7Co0.8Fe0.2O3-δ composite material as novel catalytic cathode for ceria-carbonate electrolyte fuel cells2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 178, 385-391 p.Article in journal (Refereed)
    Abstract [en]

    This work reports a new composite BaxCa1-xCoyFe1-yO3-delta (BCCF) cathode material for advanced and low temperature solid oxide fuel cells (SOFCs). The BCCF-based composite material was synthesized by sol gel method and investigated as a catalytic cathode for low temperature (LT) SOFCs. XRD analysis of the as-prepared material revealed the dominating BCCF perovskite structure as the main phase accompanied with cobalt and calcium oxides as the secondary phases resulting into an overall composite structure. Structure and morphology of the sample was observed by Field Emission Scanning Electron Microscope (FE-SEM). In particular, the Ba0.3Ca0.7Co0.8Fe0.2O3-delta (BCCF37) showed a maximum conductivity of 143 S cm(-1) in air at 550 degrees C measured by DC 4 probe method. The BCCF at the optimized composition exhibited much higher electrical conductivities than the commercial Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) perovskite cathode material. A maximum power density of 325 mW cm(-2) at 550 degrees C is achieved for the ceria-carbonate electrolyte fuel cell with BCCF37 as the cathode material.

  • 3. Behm, Mårten
    et al.
    Irvine, J. T. S.
    Influence of structure and composition upon performance of tin phosphate based negative electrodes for lithium batteries2002In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 47, no 11, 1727-1738 p.Article in journal (Refereed)
    Abstract [en]

    Tin oxide and amorphous tin borophosphates have recently received significant attention as possible new negative electrode materials for lithium batteries. In this study. we have carefully investigated a number of different well-characterised tin phosphates as electrodes in Li-ion cells, in order to better understand the mode of operation of these materials and how their performance is related to structure and composition. The materials that were investigated were crystalline cubic and layered SnP2O7, LiSn2(PO4)(3). Sn2P2O7, and Sn-3(PO4)(2). and amorphous Sn2BPO6. Cubic SnP2O7 showed the best performance with a reversible specific charge capacity of > 360 mA h g(-1) and a capacity retention of 96% over 50 cycles when cycled between 0.02 and 1.2 V versus Li-m. The three Sn(IV) materials showed lower initial reversible capacity but better capacity retention than the three Sn(II) materials in the study. Their higher proportion of inert matrix material can partly explain this. However. cubic SnP2O7 cycled significantly better than its layered polymorph. which shows that the structure of the starting material is also of great importance. Another important conclusion drawn front the results is that it is not necessary for the starting material to be amorphous, or if crystalline, to have small grain size, to cycle well. The three pyrophosphates all show an initial reduction capacity that corresponds to around 2 Li per P2O74- unit more than is predicted by theory. This might be explained by reductive break-up of the P 0 P bond.

  • 4. Bencsik, Gábor
    et al.
    Janáky, Csaba
    Endrődi, Balázs
    University of Szeged, Hungary.
    Visy, Csaba
    Electrocatalytic properties of the polypyrrole/magnetite hybrid modified electrode towards the reduction of hydrogen peroxide in the presence of dissolved oxygen2012In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 73, 53-58 p.Article in journal (Refereed)
    Abstract [en]

    In this study, we report on the electrocatalytic behaviour of a polypyrrole/magnetite hybrid electrode towards the reduction of hydrogen peroxide. The electrocatalytic activity of the composite electrode was demonstrated by cyclic voltammetric and chrono-amperometric measurements in comparison with the identically prepared neat polymer film. The stationary reduction currents, measured at an appropriately chosen potential (here at E = -0.3 V), plotted against the peroxide concentration gave a perfect linear correlation in nitrogen atmosphere in the micromolar concentration range. The performance of the composite electrode was not affected by the presence of sulphate, nitrate or chloride anions. In the presence of dissolved oxygen a complex electrocatalytic activity was observed, involving the reduction of both oxygen and H2O2. However, a linear dependence was found also in oxygen containing media, although with much higher currents, but with the same slope (even at different oxygen concentrations). This fact may trigger the development of such hybrid electrodes towards hydrogen peroxide sensors in different aqueous (including natural) samples.

  • 5.
    Bettini, Eleonora
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Eriksson, Tom
    Bostrom, Magnus
    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.
    Influence of metal carbides on dissolution behavior of biomedical CoCrMo alloy: SEM, TEM and AFM studies2011In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 56, no 25, 9413-9419 p.Article in journal (Refereed)
    Abstract [en]

    The influence of precipitate carbides on dissolution tendency and behavior of a biomedical CoCrMo alloy was investigated at microscopic scale. SEM/EDS, TEM/EDS and XRD were performed to characterize crystallographic structure and composition of different precipitate carbides. Scanning Kelvin probe force microscope (SKPFM) was used to evaluate relative nobility of the carbides. In addition to polarization curves, in situ electrochemical AFM (EC-AFM) measurements were performed to investigate the effect of the carbides on local dissolution processes. SEM/EDS, TEM/EDS and XRD characterizations showed non-uniform structure and composition of Cr and Mo carbides. SKPFM analysis suggested the carbide boundaries as preferential sites for corrosion/dissolution process. Cyclic polarization curves of the alloy in phosphate-buffered saline (PBS) solution showed a large current density increase above a certain potential, but only a small hysteresis loop during reverse scan. No noticeable pitting corrosion was observed by SEM after the experiments. In situ AFM images of the sample in PBS showed a stable surface at potentials in the passive region and around the potential corresponding to the current increase and slight etching-like dissolution around the carbides at higher potentials. Carbide boundaries are preferential sites for metal dissolution and carbides with non-uniform composition might exhibit different dissolution rates.

  • 6.
    Bettini, Eleonora
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Kivisäkk, Ulf
    Sandvik Materials Technology.
    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.
    Study of corrosion behavior of a 22% Cr duplex stainless steel: influence of nano-sized chromium nitrides and exposure temperature2013In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 113, 280-289 p.Article in journal (Refereed)
    Abstract [en]

    Chromium nitrides may precipitate in duplex stainless steels during processing and their influence on the corrosion behavior is of great importance for the steel performance. In this study, the influence of nano-sized quenched-in chromium nitrides on the corrosion behavior of a heat treated 2205 duplex stainless steel was investigated at room temperature and 50 °C (just above critical pitting temperature). The microstructure was characterized by SEM/EDS and AFM analyses, and quenched-in nitrides precipitated in the ferrite phase were identified by TEM analysis. Volta potential mapping at room temperature suggests lower relative nobility of the ferrite matrix. Electrochemical polarization and in-situ AFM measurements in 1 M NaCl solution at room temperature show a passive behavior of the steel despite the presence of the quenched-in nitrides in the ferrite phase, and preferential dissolution of ferrite phase occurred only at transpassive conditions. At 50 °C, selective dissolution of the austenite phase was observed, while the ferrite phase with the quenched-in nitrides remained to be stable. It can be concluded that the finely dispersed quenched-in nitrides do not cause localized corrosion, whereas the exposure temperature has a strong influence on the corrosion behavior of the duplex stainless steel.

  • 7. Bora, Tanujjal
    et al.
    Kyaw, Htet H
    Dutta, Joydeep
    Center of Excellence in Nanotechnology, Asian Institute of Technology, Thailand.
    Zinc oxide–zinc stannate core–shell nanorod arrays for CdS quantum dot sensitized solar cells2012In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 68, 141-145 p.Article in journal (Refereed)
    Abstract [en]

    Nanorod arrays of zinc oxide–zinc stannate core–shell photoelectrodes were prepared by a simple hydrothermal process and cadmium sulfide (CdS) quantum dot sensitized solar cells were fabricated. The photocurrent density of the core–shell photoelectrode was found to improve by ∼2.4 times compared to ZnO nanorod photoelectrodes, due to improved surface area and charge transport in the core–shell photoelectrodes. With a thin layer of ZnS on the CdS quantum dot surface, the core–shell quantum dot sensitized solar cell demonstrated maximum power conversion efficiency of 1.24% under 1 sun illumination (AM1.5).

  • 8. Bultel, Yann
    et al.
    Wiezell, Katarina
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Jaouen, Frédéric
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Ozil, P.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Investigation of mass transport in gas diffusion layer at the air cathode of a PEMFC2005In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 51, no 3, 474-488 p.Article in journal (Refereed)
    Abstract [en]

    In a polymer electrolyte membrane fuel cell (PEMFC), slowdiffusion in the gas diffusion electrode may induce oxygen depletion when using air at the cathode. This work focuses on the behavior of a single PEMFC built with a Nafion® based MEA and an E-TEK gas diffusion layer and fed at the cathode with nitrogen containing 5, 10 and 20% of oxygen and working at different cell temperatures and relative humidities. The purpose is to apply the experimental impedance technique to cells wherein transport limitations at the cathode are significant. In parallel, a model is proposed to interpret the polarization curves and the impedance diagrams of a single PEMFC. The model accounts for mass transport through the gas diffusion electrode. It allows us to qualitatively analyze the experimental polarization curves and the corresponding impedance spectra and highlights the intra-electrode processes and the influence of the gas diffusion layer.

  • 9.
    Bursell, Martin
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Pirjamali, M.
    Kiros, Yohannes
    KTH, Superseded Departments, Chemical Engineering and Technology.
    La0.6Ca0.4CoO3, La0.1Ca0.9MnO3 and LaNiO3 as bifunctional oxygen electrodes2002In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 47, no 10, 1651-1660 p.Article in journal (Refereed)
    Abstract [en]

    A series of perovskite catalysts was investigated for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline electrolyte and at room temperature, supplied by oxygen or air. A meniscus cell was used to screen-test candidate catalysts for their bifunctionality and assess their activity for ORR at 3 mm depth of immersion (DOI) in the electrolyte. Based on the meniscus data LaNiO3, La0.1Ca0.9MnO3 and La0.6Ca0.4CoO3 were selected for further assessment in microelectrode and half-cell studies. Activity tests for the ORR and OER, Tafel slopes at high current densities and apparent activation energies for the ORR were determined using a microelectrode technique on samples of the selected perovskites, La0.1Ca0.9MnO3, La0.6Ca0.4CoO3 and LaNiO3 with and without graphite support. Tafel slopes of ca. 120 mV per decade and apparent activation energies of approximately 18 kcal mol(-1) were measured at high cathodic current densities. Cycle-life and performance of La0.1Ca0.9MnO3, La0.6Ca0.4CoO3 and LaNiO3-based gas-diffusion electrodes in half-cell configurations were tested at a constant current density of 25 mA cm(-2) With subsequent and intermittent polarizations. Similar activities resulted in the ORR, while increased numbers of cycles were observed for the La0.1Ca0.9MnO3-based electrode. Furthermore, electrode material compositions, especially PTFE contents were optimized to conform to the establishment of the three phase interactions of the electrode structure, Transmission Electron microscopy (TEM) and BET-surface area analyses were carried out in order to find out the morphological and surface properties of the perovskite materials.

  • 10.
    Chang, Tingru
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Univ Sci & Technol Beijing, Peoples R China.
    Jin, Ying
    Wen, Lei
    Zhang, Chensheng
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Zhang, Junping
    Synergistic effects of gelatin and convection on copper foil electrodeposition2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 211, 245-254 p.Article in journal (Refereed)
    Abstract [en]

    Copper foil electrodeposition has been explored using a pure titanium rotating disk electrode (RDE) in acidic electrolytes containing gelatin and/or chloride ions under different convection conditions. In the plating bath without gelatin, the results indicate that stronger convection promotes hydrogen evolution, which reduces the current efficiency during copper plating. Gelatin restrains the growth of copper grains in the lateral direction parallel to the surface. This results in grain refinement on the shiny side, an increase in local grain misorientation and in internal stresses on both the shiny and the matte side, and a reduction in their internal stress difference. At strong convection conditions and with gelatin present, copper deposits as strip-like grains along the centrifugal direction of the cross section, and finally forms a spiral-shaped pattern on the matte side. The causes of these features are discussed in detail. The combined influences of hydrogen and gelatin adsorption are further elaborated in a model for a copper deposition. The current investigation suggests that a moderate convection (somewhat lower than 1000 rpm) and a concentration of 2 ppm gelatin in the plating bath are sufficient for copper foil fabrication in the presence of chloride ions (20 ppm).

  • 11. Chen, H.
    et al.
    Gao, Y.
    Lu, Z.
    Ye, L.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. KTH, School of Information and Communication Technology (ICT), Centres, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Center on Molecular Devices, Dalian University of Technology (DUT), Dalian 116024, China.
    Copper Oxide Film In-situ Electrodeposited from Cu(II) Complex as Highly Efficient Catalyst for Water Oxidation2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 230, 501-507 p.Article in journal (Refereed)
    Abstract [en]

    Water splitting is deemed as an effective pathway for producing ideal clean energy, such as hydrogen. Here, a copper oxide film (Cu-Tris film) was prepared in-situ from a 0.2 M phosphate buffer solution (pH = 12.0) containing 1.0 mM Cu2+ and 2.0 mM Tris via controlled-potential electrodeposition. The Cu-Tris film showed a significantly low overpotential of 390 mV at a current density of 1.0 mA/cm2 for electrocatalytic water oxidation. Simultaneously, a considerably low Tafel slope of 41 mV/decade was achieved. This Cu-Tris film also exhibited a high and stable current density of ca. 7.5 mA/cm2 at 1.15 V vs. NHE for long-term electrocatalysis (10 h). These results demonstrated the superior performance of the developed Cu-Tris film, which should be attributed to the regulating effect of the five coordinated planar structure of the Cu-Tris complex precursor during the process of electrodeposition.

  • 12.
    Cornell, Ann
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Håkansson, Bo
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Ruthenium based DSA in chlorate electrolysis–critical anode potential and reaction kinetics2003In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 48, no 5, 473-481 p.Article in journal (Refereed)
    Abstract [en]

    Ruthenium based DSA®s have been investigated in chlorate electrolyte using rotating discs made from commercial electrodes. Measurements of the voltammetric charge, q*, and of iR-corrected polarisation curves up to current densities of 40 kA/m2 were recorded on new anodes and on aged anodes from 3 years of production in a chlorate plant. Anodic polarisation curves in chloride containing electrolytes bend towards a higher slope at approximately 1.2 V versus Ag/AgCl, likely due to oxidation of ruthenium. The potential and current density at which the curves bend have been defined as the critical potential, Ecr, and the critical current density, icr. New anodes that operate at a relatively high potential, >Ecr, obtain an increase in real surface area and thereby a decrease in anode potential and in the selectivity for oxygen formation during the first months of operation. Experiments at constant ionic strength under chlorate process conditions showed that Ecr decreased with increasing chloride concentration with a factor of −0.09 V/log Cl, whereas icr increased with increasing chloride concentration. The chlorine evolution reaction was of the first order with respect to chloride concentration. A possible reaction mechanism for chlorine formation is suggested.

  • 13.
    Cornell, Ann
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Simonsson, Daniel
    KTH, Superseded Departments, Chemical Engineering and Technology.
    The effect of addition of chromate on the hydrogen evolution reaction and on iron oxidation in hydroxide and chlorate solutions1992In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 37, no 10, 1873-1881 p.Article in journal (Refereed)
    Abstract [en]

    The addition of chromate to the electrolyte has been shown in previous papers to hinder almost completely the electroreduction of hypochlorite, while the hydrogen evolution reaction can still proceed on the cathode surface. The effect of chromate on the latter reaction has been studied with cyclic voltammetry and by measuring polarization curves for iron electrodes in both chlorate and hydroxide electrolyte. For the sake of comparison, the investigations have also included the effects on the gold electrode in hydroxide solution. The results showed that the kinetics is changed in a way that decreases the differences in electrocatalytic activity between different electrode materials. Also, the innermost layer of the chromium hydroxide film seems to be the most active part in the HER. The chromate also affects the oxidation of the iron surface. A practical result of this is that the activity for the HER on corroded iron in chlorate electrolyte depends on whether the electrolyte contained chromate during the period of corrosion. The activation becomes much smaller if chromate is present.

  • 14. Cornell, Ann M.
    et al.
    Hakansson B,
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Ruthenium based DSA((R)) in chlorate electrolysis - critical anode potential and reaction kinetics2003In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 48, no 5, 473-481 p.Conference paper (Refereed)
    Abstract [en]

    Ruthenium based DSA((R))s have been investigated in chlorate electrolyte using rotating discs made from commercial electrodes. Measurements of the voltammetric charge, q*, and of iR-corrected polarisation curves up to current densities of 40 kA/m(2) Were recorded on new anodes and on aged anodes from 3 years of production in a chlorate plant. Anodic polarisation curves in chloride containing electrolytes bend towards a higher slope at approximately 1.2 V versus Ag/AgCl, likely due to oxidation of ruthenium. The potential and current density at which the curves bend have been defined as the critical potential, E-cr, and the critical current density, i(cr). New anodes that operate at a relatively high potential, > E-cr, obtain an increase in real surface area and thereby a decrease in anode potential and in the selectivity for oxygen formation during the first months of operation. Experiments at constant ionic strength under chlorate process conditions showed that E-cr decreased with increasing chloride concentration with a factor of -0.09 V/log Cl-, whereas i(cr) increased with increasing chloride concentration. The chlorine evolution reaction was of the first order with respect to chloride concentration. A possible reaction mechanism for chlorine formation is suggested.

  • 15.
    Crespo, Gaston A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Recent Advances in Ion-selective membrane electrodes for in situ environmental water analysis2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 245, 1023-1034 p.Article, review/survey (Refereed)
    Abstract [en]

    Ion-selective membrane electrodes (ISEs) have become very attractive sensing platforms for environmental water analysis. This review mainly presents recent advances in polymeric-based ISEs relevant to water research and primarily focused on alkali and alkali earth-metal cations, ammonium ions, halide anions and certain oxoanions involved in biogeochemical cycles (e.g. nutrients (NO2 −, NO3 −), carbon (HCO3 −/CO3 2−) and phosphorus (HPO4 2−/H2PO4 −)). Clearly, ISEs have the potential to be the icon of decentralized ion chemical information for water research as in the case of wearable ISE sensors. The modern development of robust ISEs (mainly in all-solid-state format) has allowed an easy implementation either into submersible or non-submersible probes that maintain, to an acceptable degree, the required analytical performance. Remarkable benefits, such as avoidance of sample contamination, sample preservation and determination of perturbations of chemical speciation, are significant to enhancing the fundamental knowledge of ongoing biogeochemical process. A perspective on the current requirements of ISEs in terms of analytical performance and engineering construction is provided initially and is followed by recent contributions listed according to the sampling methodology, including i) on-board/on-site sampling with subsequent coverage of decentralized analysis (on moving or fixed platforms) and ii) in situ monitoring with submersible sensing probes. On the one hand, there is difficulty in making a general statement about ISEs for water research, specifically in terms of whether they are suitable. This lies in the complexity and heterogeneity of the samples. Accordingly, particular scenarios are discussed. On the other hand, it is also evident that further steps are still needed at the fundamental level, including development of receptors, robust membranes and novel alternatives that would enable the sensing of ions at deep-sea. Importantly, there is a plenty of room for improvement and new approaches; and it should be stressed that the recent progress in water research using ISEs has been owing to multidisciplinary efforts. Facing this challenge is very exciting and the development of ISE platforms that enable working in real conditions is quite plausible.

  • 16. Crespo, Gaston A.
    et al.
    Afshar, Majid Ghahraman
    Barrabes, Noelia
    Pawlak, Marcin
    Bakker, Eric
    Characterization of Salophen Co(III) Acetate Ionophore for Nitrite Recognition2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 179, 16-23 p.Article in journal (Refereed)
  • 17. Cuartero, Maria
    et al.
    Acres, Robert G.
    Bradley, John
    Jarolimova, Zdenka
    Wang, Lu
    Bakker, Eric
    Crespo, Gaston A.
    University of Geneva, Switzerland.
    De Marco, Roland
    Electrochemical Mechanism of Ferrocene-Based Redox Molecules in Thin Film Membrane Electrodes2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 238, 357-367 p.Article in journal (Refereed)
    Abstract [en]

    Cyclic voltammetry (CV) in chloride-based aqueous electrolytes of ferrocene molecule doped thin membranes (similar to 200 nm in thickness) on glassy carbon (GC) substrate electrodes, both plasticized poly (vinyl chloride) (PVC) and unplasticized poly(methyl methacrylate)/poly(decyl methacrylate) (PMMA-PDMA) membranes, has shown that the electrochemical oxidation behavior is irreversible due most likely to degradation of ferrocene at the buried interface (GC vertical bar membrane). Furthermore, CV of the ferrocene molecules at GC electrodes in organic solvents employing chloride-based and chloride-free organic electrolytes has demonstrated that the chloride anion is inextricably linked to this irreversible ferrocene oxidation electrochemistry. Accordingly, we have explored the electrochemical oxidation mechanism of ferrocene-based redox molecules in thin film plasticized and unplasticized polymeric membrane electrodes by coupling synchrotron radiation-X-ray photoelectron spectroscopy (SR-XPS) and near edge X-ray absorption fine structure (NEXAFS) with argon ion sputtering to depth profile the electrochemically oxidized thin membrane systems. With the PVC depth profiling studies, it was not possible to precisely study the influence of chloride on the ferrocene reactivity due to the high atomic ratio of chloride in the PVC membrane; however, the depth profiling results obtained with a chlorine-free polymer (PMMA-PDMA) provided irrefutable evidence for the formation of a chloride-based iron product at the GC| PMMA-PDMA interface. Finally, we have identified conditions that prevent the irreversible conversion of ferrocene by utilizing a high loading of redox active reagent and/or an ionic liquid (IL) membrane plasticizer with high ionicity that suppresses the mass transfer of chloride.

  • 18. Danielsson, Carl-Ola
    et al.
    Dahlkild, Anders
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Velin, Anna
    Behm, Mårten
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    A Model for the Enhanced Water Dissociation On Monopolar Membranes2009In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 54, no 11, 2983-2991 p.Article in journal (Refereed)
    Abstract [en]

    A model for the enhanced water dissociation that takes place at the solution/membrane interface in electromembrane processes is presented. The mechanisms behind the enhanced water dissociation are poorly understood and therefore a semi-empirical approach is suggested. The enhanced water dissociation is introduced as a heterogeneous surface reaction similar to the well established Butler–Volmer law for electrode reactions. In the model there are two parameters that need to be determined through experiments. A 1D diffusion boundary layer problem is presented and solved in order to show that a sufficient rate of water dissociation can be obtained with the model. The advantage of the presented model is that it can easily be incorporated into simulations of electromembrane processes such as electrodialysis, electrodeionization and electropermutation. The influence of the enhanced water dissociation on these processes can then be studied.

  • 19. Darab, Mandi
    et al.
    Barnett, Alejandro Oyarce
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry. SINTEF, Norway.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Thomassen, Magnus Skinlo
    Sunde, Svein
    The Influence of Catalyst Layer Thickness on the Performance and Degradation of PEM Fuel Cell Cathodes with Constant Catalyst Loading2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 232, 505-516 p.Article in journal (Refereed)
    Abstract [en]

    Three catalytic layers containing Pt nanoparticles supported on high surface area carbon of different Pt loading but with the same total amount of platinum and therefore of different thickness were employed as cathode catalytic layers (CCLs) in a PEM fuel cell. The layers were subjected to a degradation protocol with an upper potential limit of 1.5 V. Upon exposure to the degradation protocol particle size increased, the electrochemical areas (ECAs) of the catalysts decreased, the catalytic layers became thinner, and the average pore size decreased, indicating both carbon and Pt corrosion. The relative decrease in the ECA was approximately the same for all three layers and was therefore approximately independent of CCL thickness. For all samples the reaction order with respect to oxygen was one half and the samples showed doubling of the slope of the potential vs. log current curve (dEld logi) at high current densities. This indicates that kinetics control the potential at low currents and kinetics and proton migration (ohmic drops in the catalytic layer) at high. However, the degradation protocol also introduced limitations due to oxygen diffusion in the agglomerates. This led to a quadrupling of the dEld logi-slope in 13% oxygen in the samples with the highest catalyst area per volume. For the sample with the lowest catalyst area per volume this slope increased by a factor of six in 13% oxygen, indicating that the local current density exceeded that required for the Tafel slope of the oxygen-reduction reaction (ORR) to double.

  • 20.
    Davoodi, Ali
    et al.
    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.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Norgren, S.
    Sapa Technology, Finspång.
    Integrated AFM and SECM for in situ studies of localized corrosion of Al alloys2007In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 52, no 27, 7697-7705 p.Article in journal (Refereed)
    Abstract [en]

    Rolled 3xxx series Al alloys, e.g., EN AW-3003, are generally used as fin or tube material in heat exchangers for automobiles. With reducing fin thickness, maintaining fin material integrity is of increasing importance. This study aimed at exploring the differences in intrinsic corrosion properties between EN AW-3003 and a newly developed Al–Mn–Si–Zr fin alloy using state-of-the-art local probing techniques. Volta potential mapping of both alloys by scanning Kelvin probe force microscopy (SKPFM) indicates a cathodic behaviour of constituent intermetallic particles (>0.5 μm) relative to the alloy matrix. Compared to EN AW-3003, the Al–Mn–Si–Zr alloy has a smaller number of particles with large Volta potential difference relative to the matrix. In situ atomic force microscopy (AFM) measurements in slightly corrosive solutions showed extensive localized dissolution and deposition of corrosion products on EN AW-3003, and only a small number of corroding sites and “tunnel-like” pits on Al–Mn–Si–Zr. Probing the ongoing localized corrosion process by integrated AFM and scanning electrochemical microscopy (SECM) revealed more extensive local electrochemical activity on EN AW-3003 than on Al–Mn–Si–Zr. In all, the lower corrosion activity and smaller tunnel-like pits resulted in lower material loss of the Al–Mn–Si–Zr alloy, a beneficial property when striving towards thinner fin material.

  • 21. Ding, Xin
    et al.
    Gao, Yan
    Fan, Ting
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ji, Yongfei
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Zhang, Linlin
    Yu, Ze
    Ahlquist, Mårten S. G.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. Dalian University of Technology (DUT), China.
    Silicon Compound Decorated Photoanode for Performance Enhanced Visible Light Driven Water Splitting2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 215, 682-688 p.Article in journal (Refereed)
    Abstract [en]

    An efficient dye (1) sensitized photoelectrochemical cell (DS-PEC) has been assembled with a silicon compound (3-chloropropyl) trimethoxy-silane (Si-Cl) decorated working electrode (WE) TiO2(1 + 2). The introduction of this Si-Cl molecule on photoanode leads to better performances on efficiency than untreated ones for light driven water splitting. The firm Si-O layer formed on TiO2 increased the resistance of the TiO2/catalyst interface which is assumed to decrease charge recombination from TiO2 to the oxidized catalyst 2. The work presented here provides an effective method to improve the performances of DS-PECs.

  • 22. Ding, Xin
    et al.
    Gao, Yan
    Zhang, Linlin
    Yu, Ze
    Liu, Jianhui
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Artificial photosynthesis: A two-electrode photoelectrochemical cell for light driven water oxidation with molecular components2014In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 149, 337-340 p.Article in journal (Refereed)
    Abstract [en]

    An efficient two-electrode molecular PEC was assembled, in which a photoanode was constructed using a co-adsorbed method with a molecular photosensitizer (PS) 1 and a molecular catalyst 2 on TiO2-sintered FTO electrode (TiO2(1 + 2)). Without applied bias against a reference electrode, the system achieves remarkable photocurrent densities and carries out light driven water oxidation as evidenced by Clark electrode measurements in solution. A photocurrent density of 70 mA/cm(2) has been obtained within 10 s illumination time, and a TON of about 220 was obtained with a maximum turnover frequency (TOF) of ca. 4 min(-1) within the initial 5 minutes illumination duration.

  • 23. Dobrota, Ana S.
    et al.
    Pasti, Igor A.
    Mentus, Slavko V.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala University, Sweden.
    Skorodumova, Natalia V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala University, Sweden.
    Functionalized graphene for sodium battery applications: the DFT insights2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 250, 185-195 p.Article in journal (Refereed)
    Abstract [en]

    Considering the increasing interest in the use of graphene-based materials for energy conversion and storage applications, we have performed a DFT study of Na interaction with doped graphene, both in non-oxidized and oxidized forms. Oxidation seems to play the crucial role when it comes to the interaction of doped graphene materials with sodium. The dopants act as attractors of OH groups, making the material prone to oxidation, and therefore altering its affinity towards Na. In some cases, this can result in hydroxide or water formation - an irreversible change lethal for battery performance. Our results suggest that one should carefully control the oxidation level of doped graphene-based materials if they are to be used as sodium battery electrode materials as the optimal oxidation level depends on the dopant type.

  • 24. Dobrota, Ana S.
    et al.
    Pasti, Igor A.
    Skorodumova, Natalia V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala University, Sweden.
    Oxidized graphene as an electrode material for rechargeable metal-ion batteries - a DFT point of view2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 176, 1092-1099 p.Article in journal (Refereed)
    Abstract [en]

    In line with a growing interest in the use of graphene-based materials for energy storage applications and active research in the field of rechargeable metal-ion batteries we have performed a DFT based computational study of alkali metal atoms (Li, Na and K) interaction with an oxidized graphene. The presence of oxygen surface groups (epoxy and hydroxyl) alters the chemisorption properties of graphene. In particular, we observe that the epoxy groups are redox active and enhance the alkali metal adsorption energies by a factor of 2 or more. When an alkali metal atom interacts with hydroxyl-graphene the formation of metal-hydroxide is observed. In addition to a potential boost of metal ion storage capability, oxygen functional groups also prevent the precipitation of the metal phase. By simulating lithiation/de-lithiation process on epoxy-graphenes, it was concluded that the oxidized graphene can undergo structural changes during battery operation. Our results suggest that the content and the type of oxygen surface groups should be carefully tailored to maximize the performance of metal-ion batteries. This is mainly related to the control of the oxidation level in order to provide enough active centers for metal ion storage while preserving sufficient electrical conductivity.

  • 25. Dolidze, T. D.
    et al.
    Khoshtariya, D. E.
    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.
    Glaser, Julius
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Inorganic Chemistry.
    Two-equivalent electrochemical reduction of a cyano-complex Tl-III(CN)(2) (+) and the novel di-nuclear compound (CN)(5)Pt-II-Tl-III (0)2005In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 50, no 22, 4444-4450 p.Article in journal (Refereed)
    Abstract [en]

    Extending our recent insights in two-electron transfer microscopic mechanisms for a Tl-III/Tl-I redox system, the electrochemical response of glassy carbon electrode in acidified solutions of Tl-III (ClO4)(3) containing different concentrations of sodium cyanide has been extensively studied for the first time by use of cyclic voltammetry and the CVSIM curve simulation PC program. The complex [Tl-III(CN)(2)](+) has been thoroughly identified electrochemically and shown to display a single welldefined reduction wave (which has no anodic counterpart), ascribed to the two-equivalent process yielding [Tl-I(aq)](+). This behavior is similar to that of [Tl-III (aq)](3+) ion in the absence of sodium cyanide, disclosed in the previous work, and is compatible with the quasi-simultaneous yet sequential two-electron transfer pattern (with two reduction waves merged in one), implying the rate-determining first electron transfer step (resulting in the formation of a covalently interacting di-thallium complex as a metastable intermediate), and the fast second electron transfer step. Some preliminary studies of the two-equivalent reduction of directly metal-metal bonded stable compound [(CN)(5)Pt-II-Tl-III](0) has been also performed displaying two reduction waves compatible with a true sequential pattern.

  • 26. Dong, Wenjing
    et al.
    Yaqub, Azra
    Janjua, Naveed K.
    Raza, Rizwan
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei, China.
    All in One Multifunctional Perovskite Material for Next Generation SOFC2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 193, 225-230 p.Article in journal (Refereed)
    Abstract [en]

    Multifunctional roles of La0.2Sr0.25Ca0.45TiO3 (LSCT) perovskite material as anode, cathode, and electrolyte for low temperature solid oxide fuel cell (LT-SOFC) are discovered for the first time, and have been investigated via electrochemical impedance spectroscopy (EIS) and fuel cell (FC) measurements. LSCT resistance decreases prominently in FC environment as shown in this study. An improved performance was observed by compositing LSCT with samaria doped ceria (SDC) at 550 degrees C when the FC power density increased from tens of mW cm(-2) for the pure LSCT system up to hundreds of mW cm(-2). The improved conductivity of LSCT-SDC composite is highlighted. The multifunctionality of LSCT as cathode, anode and electrolyte could be attributed to different conducting behavior at high and low oxygen partial pressures and ionic conduction at intermediate oxygen partial pressures. These new discoveries not only indicate great potential for exploring multifunctional perovskites for the next generation SOFC, but also deepen SOFC science and develop new technologies.

  • 27. Ebin, B.
    et al.
    Gümen, S.
    Arslan, C.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Electrochemical properties of nanocrystalline LiFe xMn 2-xO 4 (x = 0.2-1.0) cathode particles prepared by ultrasonic spray pyrolysis method2012In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 76, 368-374 p.Article in journal (Refereed)
    Abstract [en]

    The nanocrystalline LiFe xMn 2-xO 4 (x = 0.2-1.0) particles were prepared by ultrasonic spray pyrolysis method using nitrate salts of ingredients at 800°C in air atmosphere. Particle properties were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy. Besides, cyclic voltammetry and galvanostatic tests were performed to investigate the effects of the iron substituent amount on electrochemical behavior. Particle characterization studies show that nanocrystalline particles have spinel structure and they are in submicron size range with spherical morphology. The lowest iron doped sample (LiFe 0.2Mn 1.8O 4) exhibits 117 mAh g -1 cumulative discharge capacity at 0.5 C and 88% capacity retention for 4 V plateau after 50 cycles. At higher iron concentrations, substituent tends to occupy the 8a tetrahedral sites, which prevent the lithium transport in the lattice during charge-discharge process. Increasing of the iron amount in the spinel structure causes the deterioration of the electrochemical performance.

  • 28. Edwards, M. O. M.
    et al.
    Boschloo, Gerrit
    Gruszecki, T.
    Pettersson, H.
    Sohlberg, R.
    Hagfeldt, A.
    'Electric-paint displays' with carbon counter electrodes2001In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 46, no 13-14, 2187-2193 p.Article in journal (Refereed)
    Abstract [en]

    'Electric-paint displays' are electrochromic displays with dyed nanostructured metal-oxide electrodes, e.g. viologen-derivatized nanostructured titanium dioxide electrodes. Such displays are particularly promising for applications with low switch frequency, large segment areas, and high demands on colours, background brightness, and large viewing-angles. The concept is simple and well suited for inexpensive industrial production methods. We present blue-on-white electric-paint displays with porous carbon counter electrodes. The initial results with laboratory prototypes are promising. The switch time is about 1/2 s and the reflectance in the bleached state is as high as 40-55% in the visible region. Furthermore, the display prototypes sustain more than 100 000 switching cycles without severe degradation. The results from spectroelectrochemical measurements on the assembled displays are presented.

  • 29.
    Ekström, Henrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Wickman, Björn
    Chalmers tekniska högskola, Göteborg.
    Gustavsson, Marie
    Chalmers tekniska högskola, Göteborg.
    Hanarp, Per
    Chalmers tekniska högskola, Göteborg.
    Eurenius, Lisa
    Chalmers tekniska högskola, Göteborg.
    Olsson, Eva
    Chalmers tekniska högskola, Göteborg.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Nanometer-thick films of titanium oxide acting as electrolyte in the polymer electrolyte fuel cell2007In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 52, no 12, 4239-4245 p.Article in journal (Refereed)
    Abstract [en]

    0-18nm-thick titanium, zirconium and tantalum oxide films are thermally evaporated on Nation 117 membranes, and used as thin spacer electrolyte layers between the Nation and a 3 nm Pt catalyst film. Electrochemical characterisation of the films in terms of oxygen reduction activity, high frequency impedance and cyclic voltammetry in nitrogen is performed in a fuel cell at 80 degrees C and full humidification. Titanium oxide films with thicknesses up to 18 nm are shown to conduct protons, whereas zirconium oxide and tantalum oxide block proton transport already at a thickness of 1.5 nm. The performance for oxygen reduction is higher for a bi-layered film of 3 nm platinum on 1.5 or 18 nm titanium oxide, than for a pure 3 nm platinum film with no spacer layer. The improvement in oxygen reduction performance is ascribed to a higher active surface area of platinum, i.e. no beneficial effect of combining platinum with zirconium, tantalum or titanium oxides on the intrinsic oxygen reduction activity is seen. The results suggest that TiO2 may be used as electrolyte in fuel cell electrodes, and that low-temperature proton exchange fuel cells could be possible using TiO2 as electrolyte.

  • 30.
    Endrodi, Balazs
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry. University of Szeged, Hungary.
    Simic, Nina
    Wildlock, Mats
    Cornell, Ann M.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    A review of chromium(VI) use in chlorate electrolysis: Functions, challenges and suggested alternatives2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 234, 108-122 p.Article, review/survey (Refereed)
    Abstract [en]

    Sodium chlorate is industrially produced by electrolysis of an aqueous salt solution, in which chromium ( VI) constitutes an important excipient component. It is added to a concentration of a few grams Na2Cr2O7/ liter to the electrolyte and has several functions in the process, the most important being to increase the Faradaic efficiency for hydrogen evolution in the undivided electrochemical cells. A thin film of Cr(OH)(3) x nH(2)O formed by reductive deposition on the cathodes decreases the rate of unwanted side reactions, while still enabling hydrogen evolution to occur. In addition chromium(VI) buffers the electrolyte at the optimum pH for operation and promotes the desired homogeneous reactions in the electrolyte bulk. Chromium species also affect the rates of hydrogen and oxygen evolution at the electrodes and are said to protect the steel cathodes from corrosion. Although chromium(VI) stays in a closed loop during chlorate production, chromate is a highly toxic compound and new REACH legislation therefore intends to phase out its use in Europe from 2017. A production without chromium(VI), with no other process modifications is not possible, and today there are no commercially available alternatives to its addition. Thus, there is an urgent need for European chlorate producers to find solutions to this problem. It is expected that chromium-free production will be a requirement also in other parts of the world, following the European example. As the chromium(VI) addition affects the chlorate process in many ways its replacement might require a combination of solutions targeting each function separately. The aim of this paper is to explain the role and importance of chromium(VI) in the chlorate manufacturing process. Previous achievements in its replacement are summarized and critically evaluated to expose the current state of the field, and to highlight the most promising avenues to be followed. An attempt is also made to reveal connections with other research fields (e.g. photochemical water splitting, corrosion science) facing similar problems. Allied effort of these different communities is expected to open up research avenues to the mutual benefit of these fields.

  • 31.
    Endrődi, Balázs
    et al.
    University of Szeged, Hungary.
    Kormányos, A.
    Janáky, C.
    Berkesi, O.
    Visy, C.
    Fixation of laccase enzyme into polypyrrole, assisted by chemical interaction with modified magnetite nanoparticles: A facile route to synthesize stable electroactive bionanocomposite catalysts2014In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 122, 282-288 p.Article in journal (Refereed)
    Abstract [en]

    Effective bio-electrocatalysts require stable immobilization of sufficient amounts of the bioactive component. In this study, a novel and efficient method for specific binding of laccase enzyme onto magnetite nanoparticles (NPs) is presented. The interaction between the chemically modified magnetite NPs and the enzyme was evidenced by both infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). Subsequently, the enzyme-coated magnetite NPs were successfully incorporated into polypyrrole (PPy) matrix during galvanostatic electropolymerization. The encapsulation of laccase covered NPs was proved by EQCN, TEM, and FT-IR spectroscopy; whereas the electrochemical behaviour of the formed bionanocomposite was characterized by cyclic voltammetiy. In oxygen saturated solution a cathodic charge surplus was observed, related to the electrochemical reduction of oxygen. This surplus was two times higher in the case of the laccase containing layer compared to its only magnetite containing counterpart. Kinetic aspects of the oxygen reduction reaction (ORR) on the laccase containing films were investigated by hydrodynamic voltammetry, and the four-electron route was found to be exclusive, which is promising from the fuel cell perspective. Such synergistic combination of inorganic NPs and enzymes may open new avenues in the application of these bio-nanocomposite materials.

  • 32.
    Fontes, Eduardo
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lagergren, Carina
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Simonsson, Daniel
    KTH, Superseded Departments, Chemical Engineering and Technology.
    MATHEMATICAL-MODELING OF THE MCFC CATHODE1993In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 38, no 18, 2669-2682 p.Article in journal (Refereed)
  • 33.
    Ge, Xinlei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Wang, Xidong
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Copper extraction from copper ore by electro-reduction in molten CaCl2-NaCl2009In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 54, no 18, 4397-4402 p.Article in journal (Refereed)
    Abstract [en]

    Sintered solid porous pellets of copper sulfide (Cu2S) and Cu2S/FeS were electrolysed at a cell voltage of 2.2-2.8 V to elemental Cu, S and Cu, Fe, S, respectively in molten CaCl2-NaCl at 800 degrees C under the protection of argon gas. The process parameters for optimal electrolysis are presented. The electrolysis products are characterized by microscopic techniques and XRD. The product characteristics are linked to the process parameters. The direct electrolysis of the sulfide to copper with the emission of elemental sulphur offers an attractive green process route for the treatment of copper ore.

  • 34. Georen, P.
    et al.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Characterisation and modelling of the transport properties in lithium battery polymer electrolytes2001In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 47, no 4, 577-587 p.Article in journal (Refereed)
    Abstract [en]

    The ionic transport properties of solid polymer electrolytes can limit the performance of lithium batteries and are difficult to characterise. Few characterisation methods are available and the reported results show large discrepancies and the methods do not take variations of the properties with salt concentration into account although such are typical for polymer electrolytes. In this study, numerical macroscopic modelling, using the concentrated solution theory, was employed to determine the transport properties and thermodynamic activity factor, allowing concentration-dependent parameters. A copolymer of ethylene oxide and propylene oxide with 0.11 - 2 M LiTFSI was characterised at 25 degreesC using chronopotentiometry and concentration cell experiments. The determined ionic conductivity, kappa, apparent salt diffusion coefficient, D-s and cationic transport number, t(+)(0), were in line with previous results and kappa was also verified using electrochemical impedance spectroscopy. t(+)(0) values below 0.25 were measured, showing a decrease with increasing salt concentration. It was found that it was important to take into account the concentration dependence of the transport properties as well as the ionic interaction and the activity factor of the salt. The study resulted in a transport model well suited for the system that can easily be used to simulate the electrolyte behaviour for any current.

  • 35.
    Georen, Peter
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Characterisation and modelling of the transport properties in lithium battery gel electrolytes - Part I. The binary electrolyte PC/LiClO42004In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 49, no 21, 3497-3505 p.Article in journal (Refereed)
    Abstract [en]

    A recent development trend for rechargeable lithium batteries is the use of ternary gel electrolytes. The main advantage of the gels is the mechanical rigidity, which improves as the polymer content is increased. However, the transport properties deteriorate with increasing polymer amount. This dualistic optimisation problem has caused an increased interest in understanding the transport processes in gels, however no full characterisation or modelling study could be found in the literature. In this paper, which is the first part of a study of the transport in the ternary gel system PMMA/PC/LiClO4, the liquid electrolyte PC/LiClO4 is characterised and modelled for concentrations between 0.1 and 2 M according to a previously employed methodology, based on electrochemical measurements. A model using concentration dependent interaction parameters proved to describe the results in the whole concentration region well. The cationic transport number and salt diffusivity were determined to be approximately 0.3 and 1e-10m(2)/s, respectively. The mean ionic activity factor variations prove to be substantial. Furthermore, it was demonstrated that the inter-ionic friction was important to consider at concentrations above 1 M. The fundamental friction parameters determined in this part will be used in the following part of the study to describe the friction between ions and solvent.

  • 36.
    Gil, Harveth
    et al.
    Department of Materials, University of Antioquia.
    Echavarria, Alejandro
    Department of Materials, University of Antioquia.
    Echeverria, Felix
    Department of Materials, University of Antioquia.
    Electrochemical reduction modeling of copper oxides obtained during in situ and ex situ conditions in the presence of acetic acid2009In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 54, no 20, 4676-4681 p.Article in journal (Refereed)
    Abstract [en]

    We used the potentiodynamic reduction technique to study the mechanism of copper oxide formation inthe presence of acetic acid.We performed all reductions under neutral conditions (0.1MKCl) until hydrogenevolution. We produced the copper oxides in an environment containing 0, 500, and 800 ppb aceticacid at high relative humidity. We then compared experimental results between electrochemically producedoxide films obtained by imposing anodic potentials to copper specimens in several concentrationsof pure acetic acid (1, 0.1, 0.01 and 0.001 M). We found that, as the concentration of the acid decreases,the formation of the copper oxide (I) increases.We also found the same peaks in samples produced underthe synthetic environment.We modeled the curves, taking into account the electrochemical reduction ofcopper (II) oxide (CuO), amorphous cuprite (Cu2O)am, intermediate cuprite (Cu2O)in, crystalline cuprite(Cu2O)cr, and hydrogen. These oxides have been previously detected in similar conditions. We found noevidence of copper carboxylate founding samples produced by the electrochemical method.

  • 37.
    Gode, Peter
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Jaouen, Frederic
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Sundholm, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Influence of the composition on the structure and electrochemical characteristics of the PEFC cathode2003In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 48, no 28, 4175-4187 p.Article in journal (Refereed)
    Abstract [en]

    The influence the composition of the cathode has on its structure and electrochemical performance was investigated for a Nafion content spanning from 10 to 70 wt.%. The cathodes were formed on a Nafion membrane by the spray method and using 20 wt.% Pt on Vulcan (E-TEK). Materials characterisation (SEM, STEM, gas and mercury porosimetry, electron conductivity) and electrochemical characterisation (steady-state polarisation curve, impedance spectroscopy in O-2 and current-pulse measurements in N-2) were performed. The impedance spectra were analysed using our dynamic agglomerate model. The results indicate that the agglomerate model is valid until a Nafion content of about 45 wt.%. Pt/C and Nation are homogeneously mixed for any composition and no Nafion film was observed. The cathodes containing 36-43 wt.% Nation display a single or double Tafel slope behaviour ascribed to diffusion limitations in the agglomerates. At larger Nation content, the agglomerate model can describe the curves only by assuming a diffusion coefficient 3-4 decades smaller than that of gases. At such compositions, the porosity was only 10%. These results were interpreted as a blocking of the pores and a non-percolating pore system for too large Nafion contents.

  • 38.
    Hallberg, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Vernersson, Thomas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Thyboll Pettersson, Erik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Dvinskikh, Sergey V.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Electrokinetic transport of water and methanol in Nafion membranes as observed by NMR spectroscopy2010In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 55, no 10, 3542-3549 p.Article in journal (Refereed)
    Abstract [en]
    Electrophoretic NMR (eNMR) and pulsed-field-gradient NMR (PFG-NMR) methods were used to study transport processes in situ and in a chemically resolved manner in the electrolyte of an experimental direct methanol fuel cell (DMFC) setup, constituted of several layers of Nation 117. The measurements were conducted at room temperature for membranes fully swollen by methanol-water mixtures over a wide concentration interval. The experimental setup and the experimental protocol for the eNMR experiments are discussed in detail. The magnitude of the water and methanol self-diffusion coefficients show a good agreement with previously published data while the ratio of the two self-diffusion coefficients may indicate an imperfect mixing of the two solvent molecules. On the molecular level, the drag of water and methanol molecules by protons is roughly of the same magnitude, with the drag of methanol molecules increasing with increasing methanol content. The electro-osmotic drag defined on mass-flow basis increased for methanol from a low level with increasing methanol concentration while that of water remained roughly constant. (C) 2010 Elsevier Ltd. All rights reserved.
  • 39.
    He, Yunjuan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Faculty of Computer and Information, Hubei University, Wuhan, Hubei, China.
    Fan, Liangdong
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Faculty of Computer and Information, Hubei University, Wuhan, Hubei, China.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Singh, Manish
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Zhang, Wei
    Zhao, Yufeng
    Li, Junjiao
    Zhu, Bin
    Faculty of Computer and Information, Hubei University, Wuhan, Hubei, China.
    Cobalt oxides coated commercial Ba0.5Sr0.5Co0.8Fe0.2O3-delta as high performance cathode for low-temperature SOFCs2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 191, 223-229 p.Article in journal (Refereed)
    Abstract [en]

    In order to improve the catalytic activity of commercial Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) for low-temperature solid oxide fuel cells (LTSOFC) (300-600 degrees C), CoOx has been used to modify the commercial BSCF through a solution coating approach. Phase and morphology of samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy-dispersive spectrometry (EDS), respectively. BSCF with 10 wt% CoOx exhibited an improved conductivity of 44 S/cm, and achieved a peak power density of 463 mW/cm(2) at 550 degrees C for LTSOFC, which is a 100% enhancement than that with the BSCF cathode. The cathode oxygen reduction reaction (ORR) promoted by CoOx and enhanced device performance mechanism have been proposed. This work provides a new way for the exploitation of high effective cathode materials for LTSOFCs.

  • 40.
    Hedberg, Yolanda S.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Karolinska Inst, Sweden.
    Pradhan, Sulena
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Cappellini, F.
    Karlsson, Maria-Elisa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Tech Res Inst Sweden, Sweden.
    Karlsson, H. L.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hedberg, Jonas F.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Electrochemical surface oxide characteristics of metal nanoparticles (Mn, Cu and Al) and the relation to toxicity2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 212, 360-371 p.Article in journal (Refereed)
    Abstract [en]

    Most metal nanoparticles (NPs), except noble metal NPs, rapidly form a thin surface oxide in ambient conditions. The protective properties of these oxides improve or worsen depending on the environment, e.g., the human lung. Several properties, including the chemical/electrochemical stability and defect density, determine the capacity of these surface oxides to hinder the bulk metal from further oxidation (corrosion). The aim of this study was to investigate whether electrochemical surface oxide characterization of non-functionalized base metal NPs of different characteristics (Al, Mn and Cu) can assist in understanding their bioaccessibility (metal release) in cell media (DMEM+) and their cytotoxic properties following exposure in lung epithelial (A549) cells. The composition and valence states of surface oxides of metal NPs and their electrochemical activity were investigated using an electrochemical technique based on a graphite paste electrode to perform cyclic voltammetry in buffer solutions and open circuit potential measurements in DMEM+. The electrochemical surface oxide characterization was complemented and verified by Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The open circuit potential trends in DMEM+ correlated well with metal release results in the same solution, and provided information on the kinetics of oxide dissolution in the case of Cu NPs. Extensive particle agglomeration in cell medium (DMEM+) was observed by means of photon-cross correlation spectroscopy for all metal NPs, with sedimentation taking place very quickly. As a consequence, measurements of the real dose of added non-functionalized metal NPs to cell cultures for cytotoxicity testing from a sonicated stock solution were shown necessary. The cytotoxic response was found to be strongly correlated to changes in physico-chemical and electrochemical properties of the surface oxides of the metal NPs, the most potent being Cu NPs, followed by Mn NPs. No cytotoxicity was observed for Al NPs. The electrochemical surface oxide characterization corresponded well with other tools commonly used for nanotoxicological characterization and provided additional information.

  • 41. Hjelm, A. K.
    et al.
    Eriksson, T.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Electrochemical investigation of LiMn2O4 cathodes in gel electrolyte at various temperatures2002In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 48, no 2, 171-179 p.Article in journal (Refereed)
    Abstract [en]

    A composite lithium battery electrode of LiMn2O4 in combination with a gel electrolyte (1 M LiBF4/24 wt% PMMA/1:1 EC:DEC) has been investigated by galvanostatic cycling experiments and electrochemical impedance spectroscopy (EIS) at various temperatures, i.e. -3 < T < 56 degreesC, For analysis of EIS data, a mathematical model taking into account local kinetics and potential distribution in the liquid phase within the porous electrode structure was used. Reasonable values of the double-layer capacitance, the exchange-current density and the solid phase diffusion were found as a function of temperature. The apparent activation energy of the charge-transfer ( similar to 65 kJ mol(-1)), the solid phase transfer ( similar to 45 kJ mol(-1)) and of the ionic bulk and effective conductance in the gel phase ( similar to 34 kJ mol(-1)), respectively, were also determined, The kinetic results related to ambient temperature were compared to those obtained in the corresponding liquid electrolyte. The incorporated PMMA was found to reduce the ionic conductivity of the free electrolyte, and it was concluded that the presence of 24 wt% PMMA does not have a significant influence on the kinetic properties of LiMn2O4.

  • 42. Hjelm, A. K.
    et al.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Experimental and theoretical analysis of LiMn2O4 cathodes for use in rechargeable lithium batteries by electrochemical impedance spectroscopy (EIS)2002In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 47, no 11, 1747-1759 p.Article in journal (Refereed)
    Abstract [en]

    A comparative study of the impedance response measured with composite electrodes and thin film electrodes of LiMn2O4 was conducted. The electrodes were prepared on different current collectors (i.e. aluminium, carbonised aluminium and gold) and the experiments were run at various state-of-discharge (SOD) and liquid electrolyte compositions. The impedance response was shown to be strongly dependent on the current collector used. It was demonstrated that the high-to-medium frequency semicircle can be attributed to the contact resistance between the current collector and the active electrode material and that the medium-to-low frequency semicircle can be ascribed to the active electrode material. For the analysis, a mathematical model based on a resistance between the current collector and the active electrode material, interfacial-charge transfer coupled to the double-layer charging and solid-phase diffusion was developed. Potential distribution due to porous electrode effects was also considered, Fitting the model to experimental data enabled reasonable values of the exchange-current density, the double-layer capacitance and the solid-phase diffusion coefficient. However, the very low fitted value of the effective conductivity in the liquid phase indicates that this model does not give a satisfying description of the intercalation process of LiMn2O4.

  • 43. Ihonen, J.
    et al.
    Jaouen, F.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Sundholm, G.
    A novel polymer electrolyte fuel cell for laboratory investigations and in-situ contact resistance measurements2001In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 46, no 19, 2899-2911 p.Article in journal (Refereed)
    Abstract [en]

    A novel polymer electrolyte membrane fuel cell and assembly was developed for laboratory investigations. In this cell a simultaneous measurement of clamping pressure and contact resistances is possible. In the study presented this paper, the cell was utilised in in-situ contact resistance measurements of unplated and plated stainless steel (type 316). These contact resistances were studied in situ as a function of time, clamping pressure, gas pressure and current density. Ex-situ measurements were used to validate the in-situ contact resistance measurements. The validity and error sources of the applied in-situ measurement method were studied using both computer simulations and experiments.

  • 44.
    Karlsson, Rasmus K. B.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Cornell, Ann
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Pettersson, Lars G. M.
    The electrocatalytic properties of doped TiO22015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 180, 514-527 p.Article in journal (Refereed)
    Abstract [en]

    To rationally control the catalytic properties of heterogeneous catalysts is the goal in heterogeneous (electro)catalysis research. Recent developments of theoretical methods based on density functional theory have enabled computational screening of catalysts, to achieve fundamental understanding of which catalyst is optimal for a certain reaction. In the present work, such screening is employed to elucidate the electrocatalytic properties of doped rutile TiO2. Electrodes based on this material are widely used in industrial production of, e.g., chlorine and sodium chlorate. The screening covers 38 different dopants, including all fourth, fifth and sixth row transition metals. Several dopants are predicted to activate TiO2, resulting in a material optimal either for the oxygen evolution reaction, or for selective chlorine evolution. The results can serve as a map for the rational design of electrocatalysts based on TiO2.

  • 45.
    Karlsson, Rasmus K. B.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Hansen, Heine A.
    Bligaard, Thomas
    Cornell, Ann
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Pettersson, Lars G. M.
    Ti atoms in Ru0.3Ti0.7O2 mixed oxides form active and selective sites for electrochemical chlorine evolution2014In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 146, 733-740 p.Article in journal (Refereed)
    Abstract [en]

    The electrocatalytic properties of the (1 1 0) surface of Ru-doped TiO2, Ti-doped RuO2 and the industrially important Dimensionally Stable Anode (DSA) composition Ru0.3Ti0.7O2 have been examined using density functional theory. It is found that the oxygen adsorption energy on a Ti site is strongly affected by the presence of small amounts of Ru dopant, whereas oxygen adsorption is relatively unaffected by Ti dopants in RuO2. The calculations also indicate that coordinatively unsaturated Ti sites on Ru-doped TiO2 and on Ru0.3Ti0.7O2 could form active and selective sites for Cl-2 evolution. These results suggest a reason for why DSA shows a higher chlorine selectivity than RuO2 and propose an experimental test of the hypothesis.

  • 46.
    Kiros, Yohannes
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Pirjamali, M.
    Bursell, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Reaction Engineering.
    Oxygen reduction electrodes for electrolysis in chlor-alkali cells2006In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 51, no 16, 3346-3350 p.Article in journal (Refereed)
    Abstract [en]

    Oxygen reduction electrodes, containing non-noble metal catalysts supported on high surface area carbon and wet-proofed with PTFE were tested under reaction conditions for the chlor-alkali electrolysis. Double-layer gas diffusion electrodes were prepared by rolling of an active layer and diffusion layer on a nickel wire screen, compressed and sintered at 300 degrees C. Electrochemical measurements for substantiating the activity and stability of the half-cells were conducted in 8 M NaOH by supplying oxygen at a cell temperature of 70 degrees C and a constant current load of 300 mA cm(-2). An electrolysis cell with a dimensionally stable anode (DSA) and double-layered cathode was assembled, where 4.8 M NaCl and oxygen were supplied, respectively, for the production of chlorine and NaOH. The cell performances as well as stability of the electrodes were investigated at about 80 degrees C. This study shows that by replacing the high voltage consuming hydrogen-evolving reaction and by adopting highly active electrocatalysts as cathode materials, energy savings of more than 30% could be realized.

  • 47.
    Klett, Matilda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Zavalis, Tommy
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Hellqvist Kjell, Maria
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Wreland Lindström, Rakel
    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.
    Altered electrode degradation with temperature in LiFePO4/mesocarbon microbead graphite cells diagnosed with impedance spectroscopy2014In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 141, 173-181 p.Article in journal (Other academic)
    Abstract [en]

    Electrode degradation in LiFePO4 / mesocarbon microbead graphite (MCMB) pouch cells aged at 55 °C by a synthetic hybrid drive cycle or storage is diagnosed and put into context with previous results of aging at 22 °C. The electrode degradation is evaluated by means of electrochemical impedance spectroscopy (EIS), measured separately on electrodes harvested from the cells, and by using a physics-based impedance model for aging evaluation. Additional capacity measurements, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) are used in the evaluation. At 55 °C the LiFePO4 electrode shows increased particle/electronic conductor resistance, for both stored and cycled electrodes. This differs from results obtained at 22 °C, where the electrode suffered lowered porosity, particle fracture, and loss of active material. For graphite, only cycling gave a sustained effect on electrode performance at 55 °C due to lowered porosity and changes of surface properties, and to greater extent than at low temperature. Furthermore, increased current collector resistance also contributes to a large part of the pouch cell impedance when aged at increased temperatures. The result shows that increased temperature promotes different degradation on the electrode level, and is an important implication for high temperature accelerated aging. In light of the electrode observations, the correlation between full-cell and electrode impedances is discussed.

  • 48.
    Kortsdottir, Katrin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindström, Rakel
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Åkermark, Torbjörn
    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.
    Influence of toluene contamination at the hydrogen Pt/C anode in a proton exchange membrane fuel cell2010In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 55, no 26, 7643-7651 p.Article in journal (Refereed)
    Abstract [en]

    For fuel cells run on hydrogen reformate, traces of hydrocarbon contaminants in the hydrogen gas may be a concern for the performance and lifetime of the fuel cell. This study focuses on the influence of low concentrations of toluene on the adsorption and deactivation chemistry in a proton exchange membrane (PEM) fuel cell. For this purpose cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques were employed. Results from adsorption and desorption (by oxidation or reduction) experiments performed in a humidified nitrogen or hydrogen flow in a fuel cell test cell with a mass spectrometer system connected to the outlet are presented. The influence of adsorption potential, temperature, and humidity are discussed. The results show that toluene adsorbs on the catalyst surface in a broad potential window, up to at least 0.85 V versus RHE at 80 degrees C. Adsorbed toluene oxidizes to CO2 with peak potentials above 1.0V for temperatures below 95 degrees C. Some desorption of toluene (or reduced products) may take place at potentials below 0V. In a hydrogen flow, toluene contamination in per mille concentrations leads to a continuous growth of the charge transfer resistance, while a 10-fold dilution of the toluene concentration resulted in a low and constant charge transfer resistance even for longer exposures. This indicates that a competition between toluene and hydrogen may take place on the active platinum surface at the anode.

  • 49.
    Lagergren, Carina
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Experimental determination of effective conductivities in porous molten carbonate fuel cell electrodes1998In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 44, no 2-3, 503-511 p.Article in journal (Refereed)
    Abstract [en]

    In this work an electrochemical impedance spectroscopy method fbr the determination of the effective conductivities of the pore electrolyte and electrode matrix in porous electrodes has been used. The technique has been employed on porous nickel oxide and lithium cobaltite cathodes partly flooded with lithium-potassium carbonate melt in cathode gas environment. The experimental results show that the effective conductivity of the pore electrolyte of a porous nickel oxide cathode is 0.9-2.2 Omega(-1) m(-1) at the most. If data are approximately corrected for the faradaic reaction the effective conductivity becomes 0.1-0.7 Omega(-1) m(-1). For the lithium cobaltite cathode the measured conductivity of the solid phase is similar to the data measured ex-situ. The effective conductivity of the pore electrolyte is 0.8 Omega(-1) m(-1), i.e. close to the results found for nickel oxide cathodes. The effective conductivity of the pore electrolyte calculated by means of a theoretical model is 0.5-3.5 Omega(-1) m(-1).

  • 50. Laxman, Karthik
    et al.
    Al Gharibi, Laila
    Dutta, Joydeep
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM. Sultan Qaboos University, Oman.
    Capacitive deionization with asymmetric electrodes: Electrode capacitance vs electrode surface area: Electrode capacitance vs electrode surface area2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 176, 420-425 p.Article in journal (Refereed)
    Abstract [en]

    Asymmetry of electrodes on the equilibrium salt adsorption capacity in a capacitive configuration was studied. Experiments were carried out by using activated carbon cloth (ACC) with a specific surface area and specific capacitance of similar to 1000 m(2)/g and 44 F/g as the anode and ACC coated with zinc oxide nanorods (ZnO NR) with a specific surface area and specific capacitance of 637 m(2)/g and 57 F/g as the cathode. The electrodes were characterized electrically and their salt adsorption capacities measured for various anode-cathode configurations to conclude that for multimodal electrodes, specific capacitance and not specific surface area regulates the salt adsorption capacity. The adsorption trends were analyzed and equated to an electrical model to qualitatively predict the equilibrium salt adsorption capacity, where the smaller capacitance was observed to be the limiting factor. The results in this work are especially useful for practical CDI units, where anode-cathode capacitance should be matched to achieve maximum salt removal efficiency.

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