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  • 1.
    Abbasalizadeh, Aida
    et al.
    Delft Univ Technol TU Delft, Dept Mat Sci & Engn, Mekelweg 2, NL-2628 CD Delft, Netherlands..
    Seetharaman, Seshadri
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Venkatesan, Prakash
    Delft Univ Technol TU Delft, Dept Mat Sci & Engn, Mekelweg 2, NL-2628 CD Delft, Netherlands..
    Sietsma, Jilt
    Delft Univ Technol TU Delft, Dept Mat Sci & Engn, Mekelweg 2, NL-2628 CD Delft, Netherlands..
    Yang, Yongxiang
    Delft Univ Technol TU Delft, Dept Mat Sci & Engn, Mekelweg 2, NL-2628 CD Delft, Netherlands..
    Use of iron reactive anode in electrowinning of neodymium from neodymium oxide2019Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 310, s. 146-152Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrolytic production of metallic neodymium is carried out in fused neodymium fluoride salts containing neodymium oxide. Two major challenges pertaining to neodymium production in fluoride salts are a) low solubility of neodymium oxide in fluoride melt, b) possibility of anodic gas evolution (CO, CO2, CF4, C2F6). In this study, iron is used as a reactive anode in the electrolysis process, promoting electrochemical dissolution of iron into the melt, preventing PFC (perfluorocarbon) gas evolution at the anode. Further, the rare earth oxide is converted to rare earth fluoride by the use of iron fluoride formed as the result of iron dissolution. Thus, the fluoridizing agent is constantly regenerated in-situ which enables the continuous conversion of neodymium oxide feed. The cathodic product is Nd-Fe alloy which can be used as a master alloy for the production of NdFeB magnets. 

  • 2.
    Abbrent, Sabina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen.
    Lindgren, J
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen.
    Tegenfeldt, J
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen.
    Wendsjö, Å
    Gel electrolytes prepared from oligo(ethylene glycol)dimethacrylate: glass transition, conductivity and Li+-coordination1998Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 43, nr 10-11, s. 1185-1191s. 1185-1191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of two plasticizers, propylene carbonate and dimethyl sulphoxide, as well as different salt concentrations of Li(TFSI), on properties of a polymer gel electrolyte material has been studied using differential scanning calorimetry (DSC) and ac impedance and FTIR spectroscopy. Variations of glass transition temperature and the conductivity behaviours of the systems were examined, and found to be highly dependent on the amount and type of the plasticizer used. Characteristic band-shifts in FTIR spectra, indicating coordination of lithium ions, have been found for the polymer and both the plasticizers in the corresponding binary solutions. These shifts were used to study the coordination preferences in the complete ternary electrolyte system. The combined results from the three experimental techniques have been discussed.

  • 3. Abyaneh, Morteza Y
    Electrocrystallization of lead dioxide: Analysis of the early stages of nucleation and growth2010Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 55, s. 3572-3579Artikkel i tidsskrift (Fagfellevurdert)
  • 4.
    Abyaneh, Morteza Y
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Historisk-filosofiska fakulteten, Filosofiska institutionen.
    Homogeneous and Heterogeneous Nucleation in ElectrocrystallizationInngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The belief amongst most electrochemists that the appropriate models, representing “homogeneous” and “heterogeneous” nucleation in the context of electrocrystallization, are spherical and spherical-cap shapes, respectively, is challenged. A proper foundation for modelling heterogeneous nucleation is introduced. The free energy required for the formation of a nucleus within an indent is derived and compared with that required for the formation of a nucleus onto a flat surface of an electrode. It is shown for the first time, using the classical theory of nucleation, that a much smaller free energy is required for nucleating within an indent on the surface of an electrode than nucleating onto a flat electrode surface. The applicability of the model, with the corresponding equations, to nucleation in the context of electrocrystallization is established. 

  • 5. Adhikari, A
    et al.
    Claesson, P
    YKI – Ytkemiska institutet.
    Pan, J
    Leygraf, C
    Dedinaite, A
    YKI – Ytkemiska institutet.
    Blomberg, E
    YKI – Ytkemiska institutet.
    Electrochemical behavior and anticorrosion properties of modified polyaniline dispersed in polyvinylacetate coating on carbon steel2008Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, s. 4239-4247Artikkel i tidsskrift (Fagfellevurdert)
    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 polymer was dispersed in polyvinylacetate and coated on carbon steel samples by a dipping method. The electrochemical behavior and anticorrosion properties of the coating on 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 a 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 throughout 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.

  • 6.
    Adhikari, Arindam
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Claesson, Per M.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Pani, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Deidinaitei, Andra
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Blomberg, Eva
    KTH, Skolan för kemivetenskap (CHE), Kemi, Ytkemi.
    Electrochemical behavior and anticorrosion properties of modified polyaniline dispersed in polyvinylacetate coating on carbon steel2008Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, nr 12, s. 4239-4247Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 7.
    Afzal, Muhammad
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Raza, R.
    Du, S.
    Lima, R.B.d
    Zhu, Bin
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik. 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 cells2015Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 178, s. 385-391Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 8.
    Aitola, Kerttu
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Halme, Janne
    Feldt, Sandra
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Lohse, Peter
    Borghei, Maryam
    Kaskela, Antti
    Nasibulin, Albert G.
    Kauppinen, Esko I.
    Lund, Peter D.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Highly catalytic carbon nanotube counter electrode on plastic for dye solar cells utilizing cobalt-based redox mediator2013Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 111, s. 206-209Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A flexible, slightly transparent and metal-free random network of single-walled carbon nanotubes (SWCNTs) on plain polyethylene terephthalate (PET) plastic substrate outperformed platinum on conductive glass and on plastic as the counter electrode (CE) of a dye solar cell employing a Co(II/III)tris(2,2'-bipyridyl) complex redox mediator in 3-methoxypropionitrile solvent. The CE charge-transfer resistance of the SWCNT film was 0.60 Omega cm(2), 4.0 Omega cm(2) for sputtered platinum on indium tin oxide-PET substrate and 1.7 Omega cm(2) for thermally deposited Pt on fluorine-doped tin oxide glass, respectively. The solar cell efficiencies were in the same range, thus proving that an entirely carbon-based SWCNT film on plastic is as good CE candidate for the Co electrolyte. (C) 2013 Elsevier Ltd. All rights reserved.

  • 9.
    Ali Soomro, Razium
    et al.
    University of Bristol, England; University of Sindh, Pakistan.
    Richard Hallam, Keith
    University of Bristol, England.
    Hussain Ibupoto, Zafar
    University of Sindh, Pakistan.
    Tahira, Aneela
    University of Sindh, Pakistan.
    Tufail Hussain Sherazi, Syed
    University of Sindh, Pakistan.
    Sanam Sirajjuddin; Memon, Safia
    University of Sindh, Pakistan.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Amino acid assisted growth of CuO nanostructures and their potential application in electrochemical sensing of organophosphate pesticide2016Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 190, s. 972-979Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work reports a highly sensitive electrochemical sensor for organophosphate pesticide (malathion) based on unique and attractive CuO nanostructures. The discussed nanostructures were synthesized using low temperature hydrothermal growth method utilizing green amino acids such as glycine, serine, threonine and histidine as effective bio-compatible templates. The morphological evaluation demonstrated formation of unique and attractive 1-D nanostructures reflecting the effective growth controlling and directing capabilities of the utilized amino acids. The as-synthesized CuO nanostructures were noted to possess high affinity towards malathion which enabled their application as electrode material for the development of affinity based electrochemical sensor. Although, the as-synthesized morphologies were all sensitive towards malathion but the glycine directed triangular flake-like nanostructures exhibited greater sensitivity compared to other competitors. The electrochemical behaviour of the modified electrodes was studied using cyclic voltammetry (CV) whereas, differential pulse voltammetry (DPV) was utilized for the analytical evaluation of the sensor. The developed sensor demonstrated high reproducibility, stability, wide detection window (1-12 nM), and sensitivity to detect malathion up to 0.1 nM based on suppressive signal measurement. In addition, the sensor system exhibited high anti-interference capability in the presence of common co-existing pesticides like lindane, carbendazim, and trichlorfon. The developed sensor provides an effective measure for detecting extremely low concentration of malathion with wide applicability in various fields. (C) 2015 Elsevier Ltd. All rights reserved.

  • 10. Amiri, Omid
    et al.
    Salavati-Niasari, Masoud
    Farangi, Mostafa
    Mazaheri, Mehdi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bagheri, Samira
    Stable Plasmonic-Improved dye Sensitized Solar Cells by Silver Nanoparticles Between Titanium Dioxide Layers2015Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 152, s. 101-107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Novel metal nanoparticles (NPs) are introduced as light-harvesting antennae to enhance photocurrent of photovoltaic cells. In this work, we examined the plasmonic enhancement of photocurrent in dye-sensitized solar cells with deposition of Ag NPs between different TiO2 layers. The I-V measurement showed clearly that the open-circuit voltage (V-OC) of cells doesn't depend on Ag existence in our cells configuration extremely, however the short-circuit photocurrent density (JSC) strongly depends on it. Deposition of Ag NPs on packing TiO2 layer (T1) and transparent layer of TiO2 (T-2) both had acceptable results. The solar cells performance by treatment of Ag was studied and the results indicated that time treatment of AgNO3 and KBH4 is a key parameter which has effect on the PCE of the device. Low time (1 min), hardly shows any effect while medium time (2 min) shows significant effect on device performance. Meanwhile to improve the stability of these cells, we have proposed a new sealing method to fabricate promising stabile dye synthesized solar cells.

  • 11.
    Anwar, Nargis
    et al.
    Dundalk Inst Technol, Ireland.
    Armstrong, Gordon
    Univ Limerick, Ireland.
    Laffir, Fathima
    Univ Limerick, Ireland.
    Dickinson, Calum
    Univ Limerick, Ireland.
    Vagin, Mikhail
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    McCormac, Timothy
    Dundalk Inst Technol, Ireland.
    Redox switching of polyoxometalate-doped polypyrrole films in ionic liquid media2018Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 265, s. 254-258Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The surface immobilization of the parent Dawson polyoxometalate (POM) as a counter-ion for the electropolymerization of polypyrrole (PPy) or as an electrode-adhered solid was utilized for voltammetric studies of the surface adhered POM in room temperature ionic liquids (RTIL). Illustrating the efficiency of intermediate stabilization, voltammetry at POM-modified electrodes in a PF6-based RTIL revealed richer redox behaviour and higher stabilization in comparison with aqueous electrolytes and with BF4-based RTIL, respectively. High stability of the POM-doped PPy towards continuous charge-discharge voltammetric redox cycles was confirmed by minor changes in film morphology observed after the cycling in RTILs. (c) 2017 Elsevier Ltd. All rights reserved.

    Fulltekst tilgjengelig fra 2019-12-15 13:11
  • 12. Bagheri, Narjes
    et al.
    Aghaei, Alireza
    Ghotbi, Mohammad Yeganeh
    Marzbanrad, Ehsan
    Vlachopoulos, Nick
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Haggman, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Wang, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Skunik-Nuckowska, Magdalena
    Kulesza, Pawel. J.
    Combination of Asymmetric Supercapacitor Utilizing Activated Carbon and Nickel Oxide with Cobalt Polypyridyl-Based Dye-Sensitized Solar Cell2014Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 143, s. 390-397Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A dye-sensitized solar cell (DSC) based on the metal-free organic sensitizer and the cobalt (II, III) polypyridyl electrolyte was integrated here within an asymmetric supercapacitor utilizing cobalt-doped nickel oxide and activated carbon as positive and negative electrodes, respectively. A low cost nickel foil served as intermediate (auxiliary) bifunctional electrode separating two parts of the device and permitting the DSC electrolyte regeneration at one side and charge storage within cobalt-doped nickel oxide at the other. The main purpose of the research was to develop an integrated photocapacitor system capable of both energy generation and its further storage. Following irradiation at the 100 mW cm(-2) level, the solar cell generated an open-circuit voltage of 0.8 V and short-circuit current of 8 mA cm(-2) which corresponds to energy conversion efficiency of 4.9%. It was further shown that upon integration with asymmetric supercapacitor, the photogenerated energy was directly injected into porous charge storage electrodes thus resulting in specific capacitance of 32 F g(-1) and energy density of 2.3 Wh kg(-1). The coulumbic and total (energy conversion and charge storage) efficiency of photocapacitor were equal to 54% and 0.6%, respectively.

  • 13.
    Bagheri, Narjes
    et al.
    Mat & Energy Res Ctr, Div Ceram, POB 31787-316, Karaj, Iran..
    Aghaei, Alireza
    Mat & Energy Res Ctr, Div Ceram, POB 31787-316, Karaj, Iran..
    Vlachopoulos, Nick
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Skunik-Nuckowska, Magdalena
    Univ Warsaw, Fac Chem, Pasteura 1, PL-02093 Warsaw, Poland..
    Kulesza, Pawel J.
    Univ Warsaw, Fac Chem, Pasteura 1, PL-02093 Warsaw, Poland..
    Häggman, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Boschloo, Gerrit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Univ Paris 07, Sorbonne Paris Cite, CNRS, UMR 7086,ITODYS, 15 Rue Jean Antoinede Baif, F-75205 Paris 13, France.;Sungkyankwan Univ, Sch Chem Engn, Suwon 440746, South Korea..
    Physicochemical identity and charge storage properties of battery-type nickel oxide material and its composites with activated carbon2016Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 194, s. 480-488Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structural properties of annealed nickel oxide and its composites with activated carbon (synthesized via simple precipitation methods) have been addressed using X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption/desorption method and scanning electron microscopy. The charge storage properties of materials have also been investigated in three-and two-electrode configurations by means of cyclic voltammetry and galvanostatic charging/discharging in alkaline media. The results are consistent with the view that, depending on a method of preparation, the resulting nickel oxide films may exhibit redox characteristics different from that typically observed for nickel oxide-based materials. It is demonstrated that faradaic-type (redox) reactions, that are typical for battery-like materials, contribute predominantly to the high electrode capacity of 257C g(-1) (at 0.1 A g(-1)). By combining nickel oxide with a capacitive material such as activated carbon within the two-electrode symmetric cell, systems with increased charge-storage capabilities have been obtained. The fact, that the voltage window of nickel oxide-based cell has been broadened positively from 0.6 V to 1 V upon introduction of activated carbon, has also resulted in the increase of the cell's energy and power densities as well. 

  • 14.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Georén, Peter
    Marsal, Roser
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ion conduction of branched polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolytes2011Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 57, s. 201-206Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ionic conductivity of polymer electrolytes containing branched poly (ethylene imine) (BPEI) and lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) was measured between temperatures of 20 and 70◦C and molar ratios of 20:1 and 400:1. The electrolytes were characterized by impedance spectroscopy, differential scanning calorimetry, and viscosity measurements. At room temperature, the maximum conductivity was 2×10−6 S/cm at a molar ratio of 50:1. The molar conductivity of the electrolytes displayed first a minimum and then a maximum upon increasing salt concentration. A proportionality of molar conductivity to segmental mobility was seen from glass transition temperature and viscosity measurements. Analysis of the Walden product and isoviscosity conductivity showed that the percentage of ions bound in ion pairs increased at low concentrations below 0.1 mol/kg. The average dipole moment decreased with salt concentration. The temperature dependence of the ionic conductivity showed an Arrhenius behavior.

  • 15.
    Bayrak Pehlivan, Ilknur
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Granqvist, Claes-Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Niklasson, Gunnar A
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Ion conduction mechanism of nanocomposite polymer electrolytes comprised of polyethyleneimine–lithium bis(trifluoromethylsulfonyl)imide and silica2014Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 119, s. 164-168Artikkel i tidsskrift (Fagfellevurdert)
  • 16. Behm, Mårten
    et al.
    Irvine, J. T. S.
    Influence of structure and composition upon performance of tin phosphate based negative electrodes for lithium batteries2002Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 47, nr 11, s. 1727-1738Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 17. 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 oxygen2012Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 73, s. 53-58Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 18.
    Bergman, Martin
    et al.
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    Bergfelt, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Polymerkemi.
    Sun, Bing
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Bowden, Tim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Polymerkemi.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. Uppsala Univ, Dept Chem, Angstrom Lab, SE-75121 Uppsala, Sweden..
    Johansson, Patrik
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    Graft copolymer electrolytes for high temperature Li-battery applications, using poly(methyl methacrylate) grafted poly(ethylene glycol)methyl ether methacrylate and lithium bis(trifluoromethanesulfonimide)2015Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 175, s. 96-103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For successful hybridization of heavy vehicles, high temperature batteries might be the solution. Here, high temperature solid polymer electrolytes (SPE's) based on different ratios of poly(methyl methacrylate) (PMMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA), with LiTFSI salt (at a fixed ether oxygen (EO):Li ratio of 20:1) have been prepared and investigated. The copolymers comprise PMMA backbones with grafted PEGMA side-chains containing 9 EO units. The SPE systems were characterized using Raman spectroscopy, broadband dielectric spectroscopy, differential scanning calorimetry, thermal gravimetric analysis, and electrochemical cycling in prototype cells, with a particular focus on the 83 wt% PEGMA system. The electrolytes have good thermal stabilities and dissociate the LiTFSI salt easily, while at the same time maintaining low glass transition temperatures (T-g's). Depending on the polymeric structure, ionic conductivities >1 mS cm(-1) at 110 degrees C are detected, thus providing ion transport properties for a broad range of electrochemical applications. Prototype Li vertical bar polymer electrolyte vertical bar LiFePO4 cells utilizing the SPE at 60 degrees C showed surprisingly low capacities (<20 mA h g(-1) LiFePO4), which could be due to poor electrode/electrolyte contacts.

  • 19.
    Bettini, Eleonora
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Eriksson, Tom
    Bostrom, Magnus
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Influence of metal carbides on dissolution behavior of biomedical CoCrMo alloy: SEM, TEM and AFM studies2011Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 56, nr 25, s. 9413-9419Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 20.
    Bettini, Eleonora
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Kivisäkk, Ulf
    Sandvik Materials Technology.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Study of corrosion behavior of a 22% Cr duplex stainless steel: influence of nano-sized chromium nitrides and exposure temperature2013Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 113, s. 280-289Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 21. 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 cells2012Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 68, s. 141-145Artikkel i tidsskrift (Fagfellevurdert)
    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).

  • 22.
    Brandell, Daniel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Joemetsa, Silver
    Kasemaegi, Heiki
    Aabloo, Alvo
    Molecular Dynamics modelling a small-molecule crystalline electrolyte: LiBF4(CH3O(CH2CH2O)(4)CH3)(0.5)2013Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 104, s. 33-40Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Molecular Dynamics techniques have been used to investigate structure and ion conductivity in the glyme-based crystalline electrolyte LiBF4(CH3O(CH2CH2O)(4)CH3)(0.5). The structure allows ionic transport in two distinct directions in the structure, y or z, resulting in anisotropic effects. MD simulations have also been carried out under external electric fields of 1-5 x 10(6) V/m, imposed in y- or z-directions, to induce ion transport on a short time-space scale at room temperature conditions. The MD simulations reproduce the experimentally determined structure satisfactorily, and also the unusually high cationic transport numbers (t(+) > 0.6). The simulations suggest that the ion transport is dominated by the Li-ions inside the glyme complexes, while the Li-ions outside comprise stable complexes with the generally immobilized anions. 

  • 23.
    Brandell, Daniel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Kasemägi, Heiki
    Aabloo, Alvo
    Poly(ethylene oxide)-poly(butadiene) interpenetrated networks as electroactive polymers for actuators: a molecular dynamics study2010Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 55, nr 4, s. 1333-1337Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Molecular dynamics (MD)techniques have been used to study ionic transport and coordination stability in an interpenetrating polymer (IPN) network used as electrolyte for actuator devices. The system consisted of poly(ethylene oxide) (PEO) and poly(butadiene) (PB) in a 80/20% weight ratio at a total polymer of 32%, immersed into propylene carbonate (PC) solutions of LiClO4. The system has been studied for five different concentrations of LiClO4 in PC: 0.25, 0.5, 0.75, 1.0 and 1.25 M, and with applied external electric fields of 0. 1 and 5 MV/m. It is shown that the polymer matrix has little involvement in the movement of ions and solvent, but that the polymer arrangement is important for the solvent phase nano-structure, and thereby influences the mobility. The mobility of PC is higher than of the other species in the system, but the charged species display higher mobility under external field. The field threshold level for conductivity processes is between 1 and 5 MV/m. It is argued that ion pairing, phase separation and coordination stability are important for the overall dynamic properties.

  • 24.
    Brandell, Daniel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Priimaegi, Priit
    Kasemaegi, Heiki
    Aabloo, Alvo
    Branched polyethylene/poly(ethylene oxide) as a host matrix for Li-ion battery electrolytes: A molecular dynamics study2011Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 57, s. 228-236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This article discusses the structural and dynamic properties of a model polymer electrolyte system suitable for Li-ion batteries, investigated by Molecular Dynamics simulations at 293 K. It consists of a non-polar polyethylene backbone, onto which polar oligomeric polyethylene oxide side-chains of length 4-15 EO units are attached. LiPF(6) salt is dissolved into the matrix to a concentration corresponding to a Li:EO ratio of 1:12. It is found that the system display significantly higher mobility values that linear PEO using the same concentration, which is attributed to the high side-chain dynamics and the polar/non-polar topology of the system. An optimum side-chain length of 10 EO units is found for many properties, such as the dissolution of salt, although the Li(+) ion diffusion was found to be the highest for side-chain lengths of 15 EO units: 1.54 x 10(-13) m(2) s(-1).

  • 25.
    Bryngelsson, Hanna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Eskhult, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Electrodeposition and electrochemical characterisation of thick and thin coatings of Sb and Sb/Sb2O3 particles for Li-ion battery anodes2007Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, nr 3, s. 1062-1073Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The possibilities to electrodeposit thick coatings composed of nanoparticles of Sb and Sb2O3 for use as high-capacity anode materials in Li-ion batteries have been investigated. It is demonstrated that the stability of the coatings depends on their Sb2O3 concentrations as well as microstructure. The electrodeposition reactions in electrolytes with different pH and buffer capacities were studied using chronopotentiometry and electrochemical quartz crystal microbalance measurements. The obtained deposits, which were characterised with XRD and SEM, were also tested as anode materials in Li-ion batteries. The influence of the pH and buffer capacity of the deposition solution on the composition and particle size of the deposits were studied and it is concluded that depositions from a poorly buffered solution of antimony-tartrate give rise to good anode materials due to the inclusion of precipitated Sb2O3 nanoparticles in the Sb coatings. Depositions under conditions yielding pure Sb coatings give rise to deposits composed of large crystalline particles with poor anode stabilities. The presence of a plateau at about 0.8V versus Li+/Li due to SEI forming reactions and the origin of another plateau at about 0.4 V versus Li+/Li seen during the lithiation of thin Sb coatings are also discussed. It is demonstrated that the 0.4 V plateau is present for Sb coatings for which the (0 1 2) peak is the main peak in the XRD diffractogram.

  • 26.
    Bryngelsson, Hanna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Eskhult, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Thin films of Cu2Sb and Cu9Sb2 as anode materials in Li-ion batteries2008Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, nr 24, s. 7226-7234Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thin Cu2Sb films have been prepared by heat-treating Sb films. electrodeposited on Cu substrates. The influence of the electrodeposition conditions and the heat-treatment period on composition and morphology of the films were investigated (SEM and XRD) and the obtained films were tested as anode materials for Li-ion batteries. The Cu2Sb material showed a stable capacity of 290 mAh g(-1) (close to the theoretical capacity of 323 mAh g-1) during more than 60 cycles. The presence of 9-11% (w/w) Sb2O3 in the electrodeposited films resulted in smaller particles but also slowed down formation of Cu2Sb during the heat-treatment step. The presence of Sb2O3 was found to decrease the cycling stability although structural reversibility of Cu2Sb was obtained both with and without Sb2O3. Longer heat-treatment of pure Sb films resulted in the formation of Cu9Sb2 which was shown to be reduced at a lower potential than Cu2Sb. The Cu9Sb2 was converted to Cu2Sb during repeated cycling and the capacity of the latter Cu2Sb material was found to be 230 mAh g(-1). While reduction of the materials was complicated by simultaneous formation of an SEI layer, three plateaus Could be identified during the oxidation of Li3Sb, indicating the presence of three separate one-electron oxidation reactions.

  • 27.
    Bucur, R. V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    State of the pre-adsorbed sulfur on a rough platinum electrode in voltammetric conditions: Microgravimetric measurements with electrochemical quartz crystal microbalance2013Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 87, s. 186-193Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The removal of the chemisorbed sulfur from the surface of the rough Pt electrode was investigated by combined coulometric and gravimetric measurements using the cyclic voltammetry (CV) and the electrochemical quartz crystal microbalance (EQCMB) methods. Pt surface was covered with elemental sulfur in 1 M solutions of Na2S and tiourea (TU) at open circuit potential, for a period between 60 s and 300 s. CV was performed in 0.1 M HClO4, 0.1 M NaOH and 1 M NaOH solutions, while EQCM in 1 M NaOH solution, in the air, at 296 K. The balance of the oxidation reaction was calculated with the anodic and cathodic charges involved in CV and the mass variation of the rough Pt electrode through the frequency shift of the piezoelectric sensor. Discrepancies in the mass balance calculated by coulometry and microgravimetry were ascribed to the complexity of the removal mechanism. By each cycle, S is removed from the surface as SO3 in two stages: a fraction in the anodic scan, simultaneous with the oxidation process (faradaic process) and a remaining fraction in the cathodic scan, by electro-desorption (non-faradaic process). The whole process is biased by the potential of the electrode (the electrical field at the interface). The balance can be thoroughly equilibrated by invoking a "hidden" process embedded in the cathodic scan, accountable for the non-faradaic removal of additional mass of sulfur. This process could be caused by the adsorbate-adsorbate (S*/SO3* or S*/O*) interaction and is not detectable in CV measurements. Consequently, the S coverage calculated in CV by anodic and cathodic charge balance yields lower values than the real chemisorbed amount (the symbol * represents the adsorbed state of the element).

  • 28.
    Bucur, R. V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Structure of the Voltammograms of the Platinum-Black Electrodes: Derivative Voltammetry and Data Fitting Analysis2014Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 129, s. 76-84Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Voltammograms of Pt-black electrodes were recorded in aerated 1 M HClO4 solution, at T = 298 K, for three different upper values of the oxidation potential, E-max = 1.6 V, 1.44 V and 1.39 V. Numerical differentiation of the raw data enhanced details which hardly were visible in the original voltammograms. The derivative of the anodic current resided in well defined peaks attributed to two peaks-like electrode reactions (potential range 0.6 V-1.0 V) and a smooth reaction generating the anodic current plateau, at potential higher than IV. The derivative of the cathodic peaks revealed that the cathodic current results from two reactions occurring simultaneously, but with different rates: the reduction of the adsorbed - OH* followed by that of the adsorbed-O*. The data fitting analysis was performed with the empirical kinetic equations based upon the sigmoid-like functions. The analysis confirmed the results found on the derivative voltammograms and enabled to compute the individual component of the anodic and cathodic branches. Complementary mass measurements with the electrochemical quartz crystal microbalance (EQCM) confirmed that both the oxidation and the reduction processes on the Pt-black electrodes consist of a complex succession of overlapping reactions associated with both the adsorbed - OH* and - O* species. (c) 2014 Elsevier Ltd. All rights reserved.

  • 29.
    Bucur, Romulus V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    The resting-state of the Pt-black electrode in acid solution and the structure of the adsorption layer: Coulometric and electrochemical quartz crystal microbalance measurements2012Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 62, s. 354-361Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The properties of Pt-electrodes in 1 M HClO4 solution, in air, were studied both in the resting-state and mild oxidation conditions, within the potential range of 1000 mV and 1600 mV. Cyclic voltammetry (CV) and cathodic stripping voltammetry (CSV) were used for coulometric determination of the amount of O-containing species adsorbed on the electrode surface during the oxidation-reduction reactions. Simultaneously, the mass of the adsorption layer was measured in situ, with the electrochemical quartz crystal microbalance (EQCM). The surface of the Pt-black electrode in the resting-state is covered with OH*-species (apparently a ML), which are spontaneously generated by immersion in the aqueous solution without any polarization potential. The surface of the Pt smooth electrode is covered uppermost by a sub-monolayer of oxygen, in similar conditions. The resting-state of the Pt-black electrode is characterized by a reproducible value of the rest potential, E-r = 1040 +/- 5 mV (average of 10 samples) and a reduction peak in CV mode at E'(p) = 791 +/- 7 mV (average of 10 samples). In anodic polarization conditions, PtOH* is oxidized to PtO*, in CV mode, and to Pt(O-2)*, in the potentiostatic mode. The reduction peak of PtO* in CV mode is E ''(p) = 694 +/- 9 mV (average of 10 samples), indicating a stronger bond to the surface of the electrode. The yielding of Pt(O-2)* is not fast enough to accommodate the increase of the oxidation potential by finite sweep rate of the CV mode at 10 mVs(-1). Therefore this oxidation level could not be achieved in CV mode. The prolonged oxidation in the potentiostatic mode results in the coverage of the surface of Pt-black electrode with a monolayer of (O-2)*-species.

  • 30. Bultel, Yann
    et al.
    Wiezell, Katarina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Jaouen, Frédéric
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Ozil, P.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Investigation of mass transport in gas diffusion layer at the air cathode of a PEMFC2005Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 51, nr 3, s. 474-488Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 31.
    Bursell, Martin
    et al.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Pirjamali, M.
    Kiros, Yohannes
    KTH, Tidigare Institutioner                               , Kemiteknik.
    La0.6Ca0.4CoO3, La0.1Ca0.9MnO3 and LaNiO3 as bifunctional oxygen electrodes2002Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 47, nr 10, s. 1651-1660Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 32.
    Böhme, Solveig
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    On the electrochemistry of tin oxide coated tin electrodes in lithium-ion batteries2015Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 179, s. 482-494Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As tin based electrodes are of significant interest in the development of improved lithium-ion batteries it is important to understand the associated electrochemical reactions. In this work it is shown that the electrochemical behavior of SnO2 coated tin electrodes can be described based on the SnO2 and SnO conversion reactions, the lithium tin alloy formation and the oxidation of tin generating SnF2. The CV, XPS and SEM data, obtained for electrodeposited tin crystals on gold substrates, demonstrates that the capacity loss often observed for SnO2 is caused by the reformed SnO2 layer serving as a passivating layer protecting the remaining tin. Capacities corresponding up to about 80 % of the initial SnO2 capacity could, however, be obtained by cycling to 3.5 V vs. Li+/Li. It is also shown that the oxidation of the lithium tin alloy is hindered by the rate of the diffusion of lithium through a layer of tin with increasing thickness and that the irreversible oxidation of tin to SnF2 at potentials larger than 2.8 V vs. Li+/Li is due to the fact that SnF2 is formed below the SnO2 layer. This improved electrochemical understanding of the SnO2/Sn system should be valuable in the development of tin based electrodes for lithium-ion batteries.

  • 33.
    Carlson, Annika
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Shapturenka, Pavel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Eriksson, Björn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lagergren, Carina
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Wreland Lindström, Rakel
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Electrode parameters and operating conditions influencing the performance of anion exchange membrane fuel cells2018Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 277, s. 151-160Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A deeper understanding of porous electrode preparation and performance losses is necessary to advance the anion exchange membrane fuel cell (AEMFC) technology. This study has investigated the performance losses at 50 °C for varied: Tokuyama AS-4 ionomer content in the catalyst layer, Pt/C loading and catalyst layer thickness at the anode and cathode, relative humidity, and anode catalyst. The prepared gas diffusion electrodes in the interval of ionomer-to-Pt/C weight ratio of 0.4–0.8 or 29–44 wt% ionomer content show the highest performance. Varying the loading and catalyst layer thickness simultaneously shows that both the cathode and the anode influence the cell performance. The effects of the two electrodes are shown to vary with current density and this is assumed to be due to non-uniform current distribution throughout the electrodes. Further, lowering the relative humidity at the anode and cathode separately shows small performance losses for both electrodes that could be related to lowered ionomer conductivity. Continued studies are needed to optimize, and understand limitations of, each of the two electrodes to obtain improved cell performance.

  • 34.
    Chang, Tingru
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. Univ Sci & Technol Beijing, Peoples R China.
    Jin, Ying
    Wen, Lei
    Zhang, Chensheng
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Odnevall Wallinder, Inger
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Zhang, Junping
    Synergistic effects of gelatin and convection on copper foil electrodeposition2016Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 211, s. 245-254Artikkel i tidsskrift (Fagfellevurdert)
    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).

  • 35. Chen, H.
    et al.
    Gao, Y.
    Lu, Z.
    Ye, L.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, 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 Oxidation2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 230, s. 501-507Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 36.
    Cioffi, Nicola
    et al.
    University Bari Aldo Moro, Italy.
    Colaianni, Lorenzo
    Schaefer S E Europe SRL Italy.
    Ieva, Eliana
    Solvay Solexis SpA.
    Pilolli, Rosa
    University Bari Aldo Moro, Italy.
    Ditaranto, Nicoletta
    University Bari Aldo Moro, Italy.
    Daniela Angione, Maria
    University Bari Aldo Moro, Italy.
    Cotrone, Serafina
    University Bari Aldo Moro, Italy.
    Buchholt, Kristina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Sabbatini, Luigia
    University Bari Aldo Moro, Italy.
    Torsi, Luisa
    University Bari Aldo Moro, Italy.
    Electrosynthesis and characterization of gold nanoparticles for electronic capacitance sensing of pollutants2011Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 56, nr 10, s. 3713-3720Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present study, gold/surfactant core/shell colloidal nanoparticles with a controlled morphology and chemical composition have been obtained via the so-called sacrificial anode technique, carried out in galvanostatic mode. As synthesized Au-NPs had an average core diameter comprised between 4 and 8 nm, as a function of the electrochemical process experimental conditions. The UV-Vis characterization of gold nanocolloids showed clear spectroscopic size effects, affecting both the position and width of the nanoparticle surface plasmon resonance peak. The nanomaterial surface spectroscopic characterization showed the presence of two chemical states, namely nanostructured Au(0) (its abundance being higher than 90%) and Au(I). Au-NPs were then deposited on the top of a capacitive field effect sensor and subjected to a mild thermal annealing aiming at removing the excess of stabilizing surfactant molecules. Au-NP sensors were tested towards some gases found in automotive gas exhausts. The sensing device showed the largest response towards NOx, and much smaller - if any - responses towards interferent species such as NH3, H-2, CO, and hydrocarbons.

  • 37.
    Ciosek Högström, Katarzyna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Malmgren, Sara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hahlin, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin Germany.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    The Buried Carbon/Solid Electrolyte Interphase in Li-ion Batteries Studied by Hard X-ray Photoelectron Spectroscopy2014Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 138, s. 430-436Artikkel i tidsskrift (Fagfellevurdert)
  • 38.
    Claesson, Per
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Brandner, Birgit
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Dedinaite, Andra
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    In situ confocal Raman micro-spectroscopy and electrochemicalstudies of mussel adhesive protein and ceria composite film on carbonsteel in salt solutions2013Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 107, s. 276-291Artikkel i tidsskrift (Fagfellevurdert)
  • 39.
    Cornell, Ann
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Håkansson, Bo
    Lindbergh, Göran
    KTH, Tidigare Institutioner, Kemiteknik.
    Ruthenium based DSA in chlorate electrolysis–critical anode potential and reaction kinetics2003Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 48, nr 5, s. 473-481Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 40.
    Cornell, Ann
    et al.
    KTH, Tidigare Institutioner, Kemiteknik.
    Lindbergh, Göran
    KTH, Tidigare Institutioner, Kemiteknik.
    Simonsson, Daniel
    KTH, Tidigare Institutioner, Kemiteknik.
    The effect of addition of chromate on the hydrogen evolution reaction and on iron oxidation in hydroxide and chlorate solutions1992Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 37, nr 10, s. 1873-1881Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 41.
    Crespo, Gaston A.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Recent Advances in Ion-selective membrane electrodes for in situ environmental water analysis2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 245, s. 1023-1034Artikkel, forskningsoversikt (Fagfellevurdert)
    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.

  • 42. Crespo, Gaston A.
    et al.
    Afshar, Majid Ghahraman
    Barrabes, Noelia
    Pawlak, Marcin
    Bakker, Eric
    Characterization of Salophen Co(III) Acetate Ionophore for Nitrite Recognition2015Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 179, s. 16-23Artikkel i tidsskrift (Fagfellevurdert)
  • 43. 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 Electrodes2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 238, s. 357-367Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 44.
    Cuartero, Maria
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Chai, Lijun
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Zhang, Biaobiao
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi.
    De Marco, Roland
    Univ Sunshine Coast, Fac Sci Hlth Educ & Engn, 90s Sippy Downs Dr, Sippy Downs, Qld 4556, Australia.;Univ Queensland, Sch Chem & Mol Biosci, Brisbane, Qld 4072, Australia.;Curtin Univ, Fuels & Energy Technol Inst, Perth, WA 6102, Australia..
    Crespo, Gaston A.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Ferrocene self assembled monolayer as a redox mediator for triggering ion transfer across nanometer-sized membranes2019Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 315, s. 84-93Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Modulation of ion-transfer processes across nanometer-sized voltammetry membranes by ferrocene-based self-assembled monolayer on regular glassy carbon electrode is herein demonstrated. The composition of the membrane is advantageously tuned to promote either cation or anion transfer: the presence of an exchangeable cation results in cation transfer, whereas a lipophilic salt induces anion transfer through the fulfilment of the electroneutrality of the system. When an anodic scan oxidizes ferrocene moieties in the monolayer, these are stabilized by the pairing of lipophilic anions present in the membrane. As a result, either, hydrophilic cations present in the membrane are expelled into the solution or anions enter from the solution generating hence reversible and voltammetric waves for these transfers. The use of a redox active monolayer rather than a conducting polymer film or a redox active compound into the membrane overcomes a number of drawbacks previously manifested by these systems. The confinement of the redox process in a thin film at the immediate vicinity of the membrane allows to avoid the need of elevated number of redox moieties to be sued in the membrane, therefore suppressing its acute leaching and being compatible with the incorporation of both cation and anion ionophores for the first time. In this sense, assisted transfer of lithium and chloride are shown as proof-of-concept. Here, the peak potential of the associated voltammetric waves shifts according to the Nernst equation, in analogy to potentiometric sensors. Analytical detection of lithium and chloride ions in real samples is additionally presented.

  • 45. Dahbi, Mohammed
    et al.
    Wikberg, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Saadoune, Ismael
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Gustafsson, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Svedlindh, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    A delithiated LiNi0.65Co0.25Mn0.10O2 electrode material: A structural, magnetic and electrochemical study2009Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 54, nr 11, s. 3211-3217Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A crystalline LiNi0.65Co0.25Mn0.10O2 electrode material was synthesized by the combustion method at 900 °C for 1 h. Rietveld refinement shows less than 3% of Li/Ni disorder in the structure. Lithium extraction involves only the Ni2+/Ni4+ redox couple while Co3+ and Mn4+ remain electrochemically inactive. No structural transition was detected during cycling in the whole composition range 0 < x < 1.0. Furthermore, the hexagonal cell volume changes by only 3% when all lithium was removed indicating a good mechanical stability of the studied compound. LiNi0.65Co0.25Mn0.10O2 has a discharge capacity of 150 mAh/g in the voltage range 2.5–4.5 V, but the best electrochemical performance was obtained with an upper cut-off potential of 4.3 V. Magnetic measurements reveal competing antiferromagnetic and ferromagnetic interactions – varying in strength as a function of lithium content – yielding a low temperature magnetically frustrated state. The evolution of the magnetic properties with lithium content confirms the preferential oxidation of Ni ions compared to Co3+ and Mn4+ during the delithiation process.

  • 46. Danielsson, Carl-Ola
    et al.
    Dahlkild, Anders
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Velin, Anna
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    A Model for the Enhanced Water Dissociation On Monopolar Membranes2009Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 54, nr 11, s. 2983-2991Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 47. Darab, Mandi
    et al.
    Barnett, Alejandro Oyarce
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi. SINTEF, Norway.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Thomassen, Magnus Skinlo
    Sunde, Svein
    The Influence of Catalyst Layer Thickness on the Performance and Degradation of PEM Fuel Cell Cathodes with Constant Catalyst Loading2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 232, s. 505-516Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 48.
    Davoodi, Ali
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Norgren, S.
    Sapa Technology, Finspång.
    Integrated AFM and SECM for in situ studies of localized corrosion of Al alloys2007Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 52, nr 27, s. 7697-7705Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 49.
    Deak, Peter
    et al.
    Univ Bremen, Bremen Ctr Computat Mat Sci, POB 330440, D-28334 Bremen, Germany..
    Kullgren, Jolla
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Aradi, Balint
    Univ Bremen, Bremen Ctr Computat Mat Sci, POB 330440, D-28334 Bremen, Germany..
    Frauenheim, Thomas
    Univ Bremen, Bremen Ctr Computat Mat Sci, POB 330440, D-28334 Bremen, Germany..
    Kavan, Ladislaw
    Acad Sci Czech Republic, J Heyrovsky Inst Phys Chem, Dolejkova 3, CZ-18223 Prague 8, Czech Republic..
    Water splitting and the band edge positions of TiO22016Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 199, s. 27-34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The possibility of splitting water by UV-light on a TiO2 electrode has created great interest in the material, however, it has been later questioned whether rutile can do the job at all without external bias. Anatase was suggested instead, but its efficiency is still a subject of debate. The problem is related to the position of the band edges, that is, of the Fermi-level (E-F), with respect to the redox potentials of water. Here we present hybrid-functional calculations to align the band structures with the vacuum level, assuming the rutile (110) and anatase (101) surface being exposed to water. Our results show that both are capable of water splitting if no adsorbates other than molecular water are present. On a fully hydroxylated surface (i.e., H+ and OH adsorption on undercoordinated surface oxygen and titanium atoms, respectively), E-F is only similar to 0.5 eV above the H+/H-2 potential in case of anatase, and - depending on the level of reduction roughly at, or below it for rutile. We also show, that the band edges (and E-F) shift up if OH+ groups dominate the surface, increasing the driving force for water splitting. This is in line with the experience on titania reduced in hydrogen. Our results are further confirmed by calculating E-F without the presence of water, and comparing it to work function measurements by photoelectron spectroscopy.

  • 50.
    Delices, Annette
    et al.
    Univ Paris Diderot Paris, Sorbonne Paris Cite, ITODYS UMR CNRS 7086, 15 Rue Jean Antoine de Baif, F-75205 Paris 13, France..
    Zhang, Jinbao
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Santoni, Marie-Pierre
    Univ Paris Diderot Paris, Sorbonne Paris Cite, ITODYS UMR CNRS 7086, 15 Rue Jean Antoine de Baif, F-75205 Paris 13, France..
    Dong, Chang-Zhi
    Univ Paris Diderot Paris, Sorbonne Paris Cite, ITODYS UMR CNRS 7086, 15 Rue Jean Antoine de Baif, F-75205 Paris 13, France..
    Maurel, Francois
    Univ Paris Diderot Paris, Sorbonne Paris Cite, ITODYS UMR CNRS 7086, 15 Rue Jean Antoine de Baif, F-75205 Paris 13, France..
    Vlachopoulos, Nick
    Ecole Polytech Fed Lausanne, EPFL FSB ISIC LSPM, Inst Chem Sci & Engn, Lab Photomol Sci, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland..
    Hagfeldt, Anders
    Ecole Polytech Fed Lausanne, EPFL FSB ISIC LSPM, Inst Chem Sci & Engn, Lab Photomol Sci, Chemin Alambics,Stn 6, CH-1015 Lausanne, Switzerland..
    Jouini, Mohamed
    Univ Paris Diderot Paris, Sorbonne Paris Cite, ITODYS UMR CNRS 7086, 15 Rue Jean Antoine de Baif, F-75205 Paris 13, France..
    New covalently bonded dye/hole transporting material for better charge transfer in solid-state dye-sensitized solar cells2018Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 269, s. 163-171Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel metal-free organic dye based on triarylamine functionalized by a carbazole unit is synthesized and used in solid state dye sensitized solar cells (sDSC). The carbazole is co-polymerized with bis-EDOT by in-situ photo-electrochemical polymerization leading to a hole transporting polymer material covalently bonded to the light active centre. These first photovoltaic performances results are promising in sDSCs applications.

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