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1.	Abbrent, Sabina, et al. (author) Gel electrolytes prepared from oligo(ethylene glycol)dimethacrylate : glass transition, conductivity and Li+-coordination 1998 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 43:10-11, s. 1185-1191 Journal article (peer-reviewed)abstract 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.
2.	Behm, Mårten, et al. (author) Influence of structure and composition upon performance of tin phosphate based negative electrodes for lithium batteries 2002 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 47:11, s. 1727-1738 Journal article (peer-reviewed)abstract 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.
3.	Bursell, Martin, et al. (author) La0.6Ca0.4CoO3, La0.1Ca0.9MnO3 and LaNiO3 as bifunctional oxygen electrodes 2002 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 47:10, s. 1651-1660 Journal article (peer-reviewed)abstract 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.
4.	Cornell, Ann, et al. (author) Ruthenium based DSA in chlorate electrolysis–critical anode potential and reaction kinetics 2003 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 48:5, s. 473-481 Journal article (peer-reviewed)abstract 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.
5.	Cornell, Ann, et al. (author) The effect of addition of chromate on the hydrogen evolution reaction and on iron oxidation in hydroxide and chlorate solutions 1992 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 37:10, s. 1873-1881 Journal article (peer-reviewed)abstract 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.
6.	Edwards, M. O. M., et al. (author) 'Electric-paint displays' with carbon counter electrodes 2001 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 46:13-14, s. 2187-2193 Journal article (peer-reviewed)abstract '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.
7.	Ferry, Anders, et al. (author) A Raman, ac impedance and pfg-NMR investigation of poly(ethylene oxide) dimethyl ether (400) complexed with LiCF3SO3 1997 In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 43:10-11, s. 1471-1476 Journal article (peer-reviewed)abstract ac impedance, Raman spectroscopy and pulsed field gradient NMR measurements have been conducted on solutions of poly(ethylene oxide) dimethyl ether of molecular weight 400 complexed with LiCF3SO3, as a function of salt concentration; the ether oxygen to alkali metal cation ratios (O:M) ranging from 53:1 to 563:1. From an analysis of the νs(SO3) band envelope of the triflate anion, the relative concentrations of anions in various chemical environments have been calculated. A slight redissociation effect is observed with increasing salt concentration which correlates well with an observed increase in the molar conductivity. Pulsed field gradient NMR measurements show that the 1H, 7Li and 19F self-diffusion coefficients all decrease monotonically with increasing salt concentration. Experimental conductivity data is compared to values calculated from the diffusion coefficients using the Nernst-Einstein relation. We find that the calculated values are higher for all concentrations; the discrepancy increases with decreasing salt concentration.
8.	Ferry, Anders, et al. (author) NMR and Raman studies of a novel fast-ion-conducting polymer-in-salt electrolyte based on LiCF3SO3 and PAN 2000 In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 45:8-9, s. 1237-1242 Journal article (peer-reviewed)abstract We report spectroscopic results from investigations of a novel solid polymeric fast-ion-conductor based on poly(acrylonitrile), (PAN, of repeat unit [CH2CH(CN)]n), and the salt LiCF3SO3. From NMR studies of the temperature and concentration dependencies of 7Li- and 1H-NMR linewidths, we conclude that significant ionic motion occurs at temperatures close to the glass transition temperature of these polymer-in-salt electrolytes, in accordance with a recent report on the ionic conductivity. In the dilute salt-in-polymer regime, however, ionic motion appears mainly to be confined to local salt-rich domains, as determined from the dramatic composition dependence of the ionic conductivity. FT-Raman spectroscopy is used to directly probe the local chemical anionic environment, as well as the Li+-PAN interaction. The characteristic δs(CF3) mode of the CF3SO3- anion at ∼ 750-780 cm-1 shows that the ionic substructure is highly complex. Notably, no spectroscopic evidence of free anions is found even at relatively salt-depleted compositions (e.g. N:Li ∼ 60-10:1). A strong Li+-PAN interaction is manifested as a pronounced shift of the characteristic polymer C=N stretching mode, found at ∼2244 cm-1 in pure PAN, to ∼ 2275 cm-1 for Li+-coordinated C=N moieties. Our proton-NMR data suggest that upon complexation of PAN with LiCF3SO3, the glass transition occurs at progressively lower temperatures.
9.	Ferry, Anders, et al. (author) The molar conductivity behavior in polymer electrolytes at low salt concentrations : a raman study of poly(propylene glycol) complexed with LiCF3SO3 1995 In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 40:13-14, s. 2369-2373 Journal article (peer-reviewed)abstract Raman scattering measurements have been carried out on poly(propylene glycol) complexed with LiCF3SO3 salt over a wide salt concentration range, the ether oxygen to alkali metal cation ratios (O:M) ranging from 4820:1 to 12:1. The relative concentrations of solvated anions, anion-cation pairs and ionic aggregates have been calculated from an analysis of the symmetric anion stretch. The degree of association is found to be almost constant in the O:M range 4820:1-40:1 whereafter it increases with increasing salt concentration. The results show that the dramatic increase reported for the molar conductivity in the O:M range 1000:1-40:1 cannot be explained by the redissociation of contact ion pairs or the formation of conducting triplets. Instead the major contribution to the conductivity increase seems to be a concentration dependent enhancement of the ionic mobility. A percolation based ionic hopping process involving exchange between ions in pairs and dissolved ions, either free or coordinated to ether oxygen sites, is advanced as a possible microscopic mechanism.
10.	Ferry, Anders, et al. (author) Transport property measurements of polymer electrolytes 1998 In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 43:10-11, s. 1387-1393 Journal article (peer-reviewed)abstract Straightforward electrochemical methods for determining the transport properties (bulk ionic conductivity, salt diffusion coefficient, and cation transference number) of polymer electrolytes are described herein. The new technique for measuring t0+ is:based on concentrated solution theory, and requires no assumptions to be made concerning ideality of the solution. The experimental methods are described and results on representative polymer electrolyte systems are presented in this paper. Cation transference numbers are found to be salt-concentration dependent and considerably less than unity or even negative over a wide concentration range. This implies that the cationic current is mainly carried by complexed ions. The presence of associated ionic species in the present systems is confirmed by Raman spectroscopic evidence. Finally, the practical effects of a negative t0+ on cell operation and implications for device design are discussed.
11.	Fontes, Eduardo, et al. (author) MATHEMATICAL-MODELING OF THE MCFC CATHODE 1993 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 38:18, s. 2669-2682 Journal article (peer-reviewed)
12.	Frenning, Göran, et al. (author) Dielectric and Li transport properties of electron conducting and non-conducting sputtered amorphous Ta2O5 films 2001 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 46:13-14, s. 2041-2046 Journal article (peer-reviewed)abstract Two types of sputtered thin film amorphous tantalum oxide (Ta2O5) were studied: one electron conducting Ta2O5 (ec-Ta2O5) and the other non-conducting Ta2O5 (nc-Ta2O5). The as-deposited films were characterized by impedance spectroscopy (IS) and isothermal transient ionic current (ITIC) measurements. From IS, the dc conductivity 2×10−14 S/cm was obtained for the ec-Ta2O5 film at an applied ac potential of 50 mV whereas a value ≤1×10−17 S/cm was obtained for the nc-Ta2O5 film. Li conducting properties were studied using the galvanostatic intermittent titration technique and ITIC measurements on the intercalated samples. Despite the very dissimilar dc conductivities of the as-deposited films, the two Ta2O5 samples showed surprisingly similar Li ion conducting properties for small Li/Ta2O5 ratios. The Li ion mobility was in the range 1.1×10−9–3.0×10−9 cm2/V s for both films. However, the Li storage behaviour as well as the chemical diffusion coefficient differed. For the nc-Ta2O5 film a plateau was observed in the equilibrium potential vs. composition curve for Li/Ta2O5 ratios between 7×10−5 and 2×10−3. This plateau was likely to have been caused by attractive interactions between the intercalated ions, possibly large enough to cause phase separation. The attractive interactions were shown to suppress the chemical diffusion coefficient in this composition range.
13.	Georen, P., et al. (author) Characterisation and modelling of the transport properties in lithium battery polymer electrolytes 2001 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 47:4, s. 577-587 Journal article (peer-reviewed)abstract 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.
14.	Gode, Peter, et al. (author) Influence of the composition on the structure and electrochemical characteristics of the PEFC cathode 2003 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 48:28, s. 4175-4187 Journal article (peer-reviewed)abstract 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.
15.	Hjelm, A. K., et al. (author) Electrochemical investigation of LiMn2O4 cathodes in gel electrolyte at various temperatures 2002 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 48:2, s. 171-179 Journal article (peer-reviewed)abstract 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.
16.	Hjelm, A. K., et al. (author) Experimental and theoretical analysis of LiMn2O4 cathodes for use in rechargeable lithium batteries by electrochemical impedance spectroscopy (EIS) 2002 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 47:11, s. 1747-1759 Journal article (peer-reviewed)abstract 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.
17.	Idla, K., et al. (author) Good adhesion between chemically oxidized titanium and electrochemically deposited polypyrrole 2000 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 45:13, s. 2121-2130 Journal article (peer-reviewed)abstract A method for producing extremely adhesive polypyrrole (Ppy) films is described. The electrochemical synthesis of Ppy on thin chemically pre-oxidized Ti layers produces a mechanically strong, shiny polymer film with extremely good adhesion. Adhesion of Ppy films on Ti metal without chemical pre-oxidation is very weak. Two multilayer systems are described with Ppy as an electrochemically active layer, chemically oxidized Ti (TixOy) as a thin adhesive layer, and either a Si-wafer or Al foil as a substrate. Ppy films survive more than 6000 reduction-oxidation cycles in aqueous electrolyte without delamination. The possible mechanisms of enhanced adhesion are discussed. Those are: (1) increased adhesion due to changes in the chemical composition and surface structure of the pre-oxidized Ti, (2) the possibility of the chemical oxidation of pyrrole on the metal surface in addition to the electrochemical polymerization, (3) the adsorption of pyrrole molecules onto pre-oxidized Ti surface by interaction with Ti hydroxides on surface, and (4) the simultaneous growth of TixOy and Ppy.
18.	Ihonen, J., et al. (author) A novel polymer electrolyte fuel cell for laboratory investigations and in-situ contact resistance measurements 2001 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 46:19, s. 2899-2911 Journal article (peer-reviewed)abstract 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.
19.	Inganäs, Olle, et al. (author) Phase engineering for enhanced electrochromism in conjugated polymers 2001 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 46:13-14, s. 2031-2034 Journal article (peer-reviewed)abstract Development of nanostructured blends of electrochromic polymers formed by self-assembly is reported. We have prepared blends of a polythiophene derivative, poly(3,4-ethylenedioxythiophene) and polypyrrole, combining optical and electrochemical properties of the two polymers. The route towards these blends is based on self-assembly of the former polymer into a hydrogel, and subsequent electrochemical polymerisation of the latter using the conducting hydrogel matrix as a template. When used as electrodes, these materials show very fast electrochromic response. The route used in the present work is generic and may be extended to other polymers. © 2001 Elsevier Science Ltd.
20.	Lagergren, Carina, et al. (author) Experimental determination of effective conductivities in porous molten carbonate fuel cell electrodes 1998 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 44:2-3, s. 503-511 Journal article (peer-reviewed)abstract 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).
21.	Larsson, Regina, et al. (author) Properties of electrolytes under pressure : PPG400 and PPG4000 complexed with LiCF3SO3 2003 In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 48:23, s. 3481-3489 Journal article (peer-reviewed)abstract High-pressure electrical conductivity measurements and differential thermal analysis have been carried out on poly(propylene glycol) (PPG) complexed with LiCF3SO3 (composition O:Li = 20:1) for pressures up to 1 GPa. The temperature and pressure dependence of the conductivity were analyzed in terms of the recently presented generalized Vogel equation as well as the well-known Vogel-Tamman-Fulcher equation, and the former provides an improved description of the data. The conductivity results show that the apparent activation volumes for the conduction process at room temperature and atmospheric pressure are 48 and 42 cm3 mol-1 for electrolyte based on PPG4000 (molecular weight = 4000) and PPG400, respectively. The temperature variation of the activation volume as well as the molecular weight dependence are described well within the free volume theory, which also provide a reasonable description of the pressure dependence. Differential thermal analysis was used to determine the pressure dependence of the glass transition temperature Tg for the electrolyte based on PPG400. The result for the initial slope dTg/dp = 140 K GPa-1 agrees well with that for the pure host PPG, but Tg is shifted up 6 K.
22.	Lazzaroni, R., et al. (author) The chemical and electronic structure of the interface between aluminum and conjugated polymers 1994 In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 39:2, s. 235-244 Journal article (peer-reviewed)abstract The chemical and electronic structure of the interface between aluminum and several proto-typical conjugated systems is investigated with a combined experimental and theoretical approach. The experiments consists of following the evolution of the polymer surface during the early stages of aluminum deposition, with X-ray and Ultraviolet Photoelectron Spectroscopies (XPS, UPS). In parallel, quantum chemical calculations are performed on model oligomer systems interacting with isolated Al atoms. Aluminum is found to interact strongly with the polymer chain. New covalent Al-carbon bonds are formed along the polymer backbone; the chain geometry is deeply modified and the Ï€ electron conjugation can be dramatically reduced.
23.	Lehtinen, T, et al. (author) Electrochemical characterization of PVDF-based proton conducting membranes for fuel cells 1998 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 43, s. 1881-1890 Journal article (peer-reviewed)abstract The electrochemical characterization of proton-conducting membranes prepared by irradiation-induced grafting and subsequent sulfonation of PVDF films has been performed. In particular, measurements of the ionic conductivity, oxygen solubility and diffusion in the membranes are presented, as well as kinetic data for the oxygen reduction reaction in a membrane-platinum system and a simulation of the performance of these PVDF-g-PSSA membranes in a solid polymer electrolyte fuel cell using a microcathode technique. At sufficient degrees of grafting (>40%) the conductivity reaches 0.1 Scm−1, well above that of Nafion 117 (DuPont). The PVDF-g-PSSA membranes show lower solubilities and higher diffusion coefficients of oxygen and a higher water uptake than Nafion 117. The microcathode measurements indicate that those PVDF-g-PSSA membranes which have a conductivity higher than that of Nafion 117 may also give improved performance in fuel cell conditions provided that they have the necessary mechanical and chemical stability.
24.	Lindbergh, Göran, et al. (author) Corrosion behaviour of high aluminium steels in molten carbonate in an anode gas environment 2001 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 46:8, s. 1131-1140 Journal article (peer-reviewed)abstract The corrosion behaviour of five ferritic steels with high aluminium content was investigated in (Li-0.60/Na-0.40)CO3 melt in three different anode gas environments. The corrosion potentials were measured versus time, and the electrochemical techniques used for determination of the corrosion rates were linear polarisation resistance and Tafel extrapolation. The corrosion layer formed on the surface after electrochemical tests have been analysed by scanning electron microscopy (SEM) and glow discharge optical emission spectroscopy (GDOES). The evaluation of corrosion rates and corrosion resistance from the experimental electrochemical data by the conventional Tafel extrapolation and linear polarisation equations are not valid under these conditions. Therefore, a modified theoretical model has been used to evaluate the corrosion resistance and corrosion rates. In general, the corrosion resistance of high aluminium steels in molten carbonate melt, at anode gas environment, is much higher than that of 310 and 316 stainless steels. It has been shown that lower temperatures in combination with higher concentrations of carbon dioxide result in a higher corrosion rate.
25.	Petersen, G., et al. (author) A Raman study of ion-polymer and ion-ion interactions in low molecular weight polyether - LiCF3SO3 complexes 1992 In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 37:9, s. 1495-1497 Journal article (peer-reviewed)abstract We report Raman scattering investigations of the stability of various ion—polymer interactions from studies of LiCF3SO3—polyethers. New results for endcapped polyethers of different molecular weights in the range of one to eight repeat units are compared with previous data from OH-terminated polyether salt complexes. We conclude that anions coordinated to OH-endgroups are more stable than cations forming crosslinks between oxygens of adjacent polymer chains which in turn are more stable than cations coordinated to single oxygens. It is the weak oxygen—cation bond which is causing the dramatic increase in ion—ion association as tempearature increases. OH—anion bonds are little affected by temperature.
26.	Rasmussen, A.A., et al. (author) Microstructure in electrodeposited copper layers, the role of the substrate 2001 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 47:1, s. 67-74 Journal article (peer-reviewed)abstract The microstructures of Cu layers, ranging in thickness from 3 to 12 µm, were investigated. The layers were electrodeposited from an acidic copper electrolyte onto two distinct substrate materials important for the micro-components industry: an Au layer with a pronounced <111>-texture, and a nano-crystalline Ni-P layer. The evolutions of surface topography, morphology and crystallographic texture in the layers were investigated with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction analysis, respectively. Distinct surface topographies were observed for Cu layers deposited on the Au and Ni-P substrates. Deposition onto the Au substrate resulted in a very smooth surface of all Cu layers, whereas the Ni-P substrate caused an irregular surface for 3-µm-thick layers of Cu. The crystallographic texture in the Cu layers in the first few micrometres depended strongly on the crystallographic texture in the substrate. The Cu crystallites inherited the <111>-orientation of the Au substrate, whilst no preferred crystallographic orientation was observed in the Cu crystallites on the nano-crystalline Ni-P substrate. For Cu layers thicker than 3 µm a <110>-fibre texture developed on both the substrates. © 2001 Elsevier Science Ltd. All rights reserved.
27.	Valizadeh, S., et al. (author) Electrochemical deposition of Co nanowire arrays, Quantitative consideration of concentration profiles 2001 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 47:6, s. 865-874 Journal article (peer-reviewed)abstract Electrodeposition of Co into ion track etched polycarbonate membranes by a chronoamperometric method has been studied. The concentration variation and diffusion limiting current during nanoprocessing for growth of Co in nanoelectrode applications are described for two regimes, in the vicinity of the electrode and at the mouth of pores. The behaviour of the as-deposited nanoelectrodes can be modelled as a recessed microelectrode. A diffusion controlled limiting current of the nanodes is studied by the Cottrell equation at short times, i.e. current at-1/2. At longer times, a steady-state current is obtained due to gradually increasing radii, r, of the spherical diffusion zones from each recessed nanode, i.e. current a(1/(r+L)), where L is the membrane thickness. The experimental value of diffusion coefficient D for Co ions was found: D = 2.5 × 10-5 cm2 s-1. XRD and TEM measurements on 250 nm diameter and 20 µm long Co nanowires showed a hexagonal closed packed phase with a <100> texturing. The nanowires exhibited an enhanced magnetic coercivity in comparison to bulk Co. The difference of saturation fields between the parallel and perpendicular orientation fields corresponds well to the expected demagnetisation field of 2pM = 8796 Oe value due to the shape anisotropy in case of an infinite thin Co cylinder. © 2001 Elsevier Science Ltd. All rights reserved.
28.	Zhu, B., et al. (author) Corrosion behaviour of high-chromium ferritic steels in molten carbonate in cathode environment 2001 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 46:17, s. 2593-2604 Journal article (peer-reviewed)abstract The corrosion behaviour of four ferritic steels with a high chromium content and AISI 310 was investigated in (Li-0.60/Na-0.40)(2)CO3 melt in three different cathode gas environments. The electrochemical techniques used were linear polarisation resistance and Tafel extrapolation. The corrosion layers formed on the surface during the tests were analysed by glow discharge optical emission spectroscopy (GDOES), The corrosion layer formed on the Thermax 4762 sample consists of an iron-rich outer layer and a protective aluminium- and chromium-rich inner layer. The corrosion potential increased to a more positive value as the corrosion layer grew on the surface. This supports the supposition that the cathodic reaction in the corrosion process changes gradually from water reduction to oxygen reduction. It was shown that higher temperatures and low concentrations of oxygen and carbon dioxide under so-called outlet cathode gas conditions result in higher corrosion rates.
29.	Abbasalizadeh, Aida, et al. (author) Use of iron reactive anode in electrowinning of neodymium from neodymium oxide 2019 In: Electrochimica Acta. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0013-4686 .- 1873-3859. ; 310, s. 146-152 Journal article (peer-reviewed)abstract 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.
30.	Abyaneh, Morteza Y (author) Electrocrystallization of lead dioxide : Analysis of the early stages of nucleation and growth 2010 In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 55, s. 3572-3579 Journal article (peer-reviewed)
31.	Abyaneh, Morteza Y (author) Homogeneous and Heterogeneous Nucleation in Electrocrystallization 2024 In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. Journal article (peer-reviewed)abstract 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.
32.	Adeniyi, Omotayo, et al. (author) Engineering of layered iron vanadate nanostructure for electrocatalysis : simultaneous detection of methotrexate and folinic acid in blood serum 2023 In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. Journal article (peer-reviewed)abstract In this study, nanostructure kazakhstanite-like iron vanadate (FexV3xOy.H2O) was synthesized and calcined at different temperatures (100-800 °C) in a nitrogen atmosphere. The material was used to modify screen-printed carbon electrodes to achieve an electrocatalytic effect on the surface. The relationship between calcination conditions and the catalytic performance of the electrode towards the oxidation of chemotherapeutic drugs, including methotrexate (MTX) and folinic acid (FA), was studied. Various spectroscopic, microscopic, and electrochemical methods were used to characterize the synthesized materials. The results show that calcination induces changes in the electronic structure, nanostructure morphology, electroactive surface area, and electrocatalytic performance of the material. Screen-printed carbon electrode modified with FexV3xOy calcinated at 450 °C (SPC/FexV3xOy-450) was used to develop a voltammetric sensor for the determination of MTX and FA in blood serum. The response of the SPC/FexV3xOy-450 towards the electrooxidation of MTX and FA was the highest in comparison to the bare SPC and SPC/FexV3xOy calcined at other temperatures. The SPC/FexV3xOy-450 exhibited a linear relationship over a wide concentration range: 0.005-200 µM for MTX and 0.05-200 µM for FA. The detection limit was 2.85 nM for MTX and 7.79 nM for FA. Compared to conventional methods, the SPC/FexV3xOy-450 sensor had a short response time (5 min) for simultaneous detection of MTX and FA without signal interferences from coexisting electroactive compounds. The accurate and precise determination of MTX in the presence of FA confirmed the potential clinical applications of SPC/FexV3xOy-450 for therapeutic drug monitoring during chemotherapy.
33.	Adhikari, Arindam, et al. (author) Electrochemical behavior and anticorrosion properties of modified polyaniline dispersed in polyvinylacetate coating on carbon steel 2008 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 53:12, s. 4239-4247 Journal article (peer-reviewed)abstract 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.
34.	Afzal, Muhammad, et al. (author) Synthesis of Ba0.3Ca0.7Co0.8Fe0.2O3-δ composite material as novel catalytic cathode for ceria-carbonate electrolyte fuel cells 2015 In: Electrochimica Acta. - : Pergamon Press. - 0013-4686 .- 1873-3859. ; 178, s. 385-391 Journal article (peer-reviewed)abstract 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.
35.	Ahmed, Bilal, et al. (author) Electrochemical activation of commercial graphite sheets for supercapacitive applications 2022 In: Electrochimica Acta. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0013-4686 .- 1873-3859. ; 431 Journal article (peer-reviewed)abstract Carbon-based substrates are widely used as current collectors for high-performance energy storage materials in supercapacitors. However, these substrates exhibit negligible charge storage due to inferior electrochemical activity and small surface area. Herein, electrochemical activation is utilized to enhance the electrochemical activity of - inherently inactive - commercial graphite sheets for supercapacitive applications. The results reveal that the electrochemically activated graphite sheets render a 30-fold increase in areal capacitance, i.e., from 22 to 447 mF cm(-2), which can be ascribed to the activation of graphite oxide functional groups on the surface. Also, the influence of electrochemical activation time on electrochemical performance is explored in detail, followed by the fabrication and characterization of symmetric supercapacitors based on the optimum process parameters in single-cell and tandem configurations, demonstrating the potential of electrochemically activated graphite sheets in practical applications.
36.	Aitola, Kerttu, et al. (author) Highly catalytic carbon nanotube counter electrode on plastic for dye solar cells utilizing cobalt-based redox mediator 2013 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 111, s. 206-209 Journal article (peer-reviewed)abstract 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.
37.	Alferov, Sergey, et al. (author) Electrical communication of cytochrome enriched Escherichia coli JM109 cells with graphite electrodes 2009 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 54:22, s. 4979-4984 Conference paper (peer-reviewed)abstract In the present study three different strains of Escherichia coli (JM 109 - a native "wild type" strain, JM 109/pBSD 1300 - a strain overproducing the membrane anchor domain of Bacillus subtilis succinate-quinone reductase, SQR, a protein that contains two transmembraneously arranged heme groups and JM109/pLUV 1900 - a strain overproducing cytochrome c(550) from B. subtilis, a protein where the cytochrome domain is anchored to the membrane with a transmembrane helix) were immobilised on the surface of a spectrographic graphite electrode and tested for electrical communication using mediators. Such compounds as ferricyanide, 2,6-dichlorophenolindophenol (DCPIP) and ubiquinone (Q(0)) were used as soluble mediators and two flexible osmium redox polymers; poly(1-vinylimidazole)(12)-[Os-(4,4'-dimethyl-2,2'-di'pyridyl)(2)Cl-2](2 +/+) (osmium redox polymer I) and poly(vinylpyridine)-[Os-(N,N'-methylated-2,2'-biimidazole)(3)](2+/3+) (osmium redox polymer II) were co-immobilised with the bacterial cells onto the electrode surface. The effects of applied potential, buffer pH and different substrates were compared for the different combinations bacterial strains - mediators. Through the introduction of the cytochromes in the bacterial membrane it was established that it had great effect on the ability of the bacterial cells to effectively communicate with artificial mediators. The introduction of the transmembraneously arranged heme groups of B. subtilis made it possible for this strain to communicate with the Os-polymers, whereas the introduction of the cytochrome c(550) had an effect especially increasing ability of Q(0) to act as an efficient e(-) acceptor. (C) 2009 Elsevier Ltd. All rights reserved.
38.	Ali Soomro, Razium, et al. (author) Amino acid assisted growth of CuO nanostructures and their potential application in electrochemical sensing of organophosphate pesticide 2016 In: Electrochimica Acta. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0013-4686 .- 1873-3859. ; 190, s. 972-979 Journal article (peer-reviewed)abstract 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.
39.	Amiri, Omid, et al. (author) Stable Plasmonic-Improved dye Sensitized Solar Cells by Silver Nanoparticles Between Titanium Dioxide Layers 2015 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 152, s. 101-107 Journal article (peer-reviewed)abstract 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.
40.	Anwar, Nargis, et al. (author) Redox switching of polyoxometalate-doped polypyrrole films in ionic liquid media 2018 In: Electrochimica Acta. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0013-4686 .- 1873-3859. ; 265, s. 254-258 Journal article (peer-reviewed)abstract 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.
41.	Atak, Gamze, et al. (author) Electrochromic tungsten oxide films prepared by sputtering : Optimizing cycling durability by judicious choice of deposition parameters 2021 In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 367 Journal article (peer-reviewed)abstract Thin films of W oxide were prepared by reactive DC magnetron sputtering (5 cm-diameter W target), and their electrochromic (EC) properties were investigated in an electrolyte of LiClO4 in propylene carbonate. The purpose of the study was to elucidate the role of critical deposition parameters-oxygen/argon gas flow ratio for the sputter plasma Gamma, total pressure in the sputter plasma p(tot) , and sputtering power P-s - on the EC performance with foci on electrochemical cycling durability and optical modulation range Delta T. Specifically, we used 0.15 <= Gamma <= 0.90, 5 <= p(tot) <= 30 mTorr, and 200 <= P-s <= 400 W and studied cycling durability for up to 500 voltammetric cycles in the range 2.0-4.0 V vs. Li/Li+ together with optical properties at a wavelength of 528 nm. Most significantly, we discovered that a judicious choice of deposition parameters could yield films with superior cycling durability. Thus a similar to 300 nm-thick film prepared at Gamma = 0.90, p(tot) = 10 mTorr, and P-s = 200 W showed Delta T approximate to 65% after an initial "training" during similar to 100 voltammetric cycles; higher values of p(tot), on the other hand, yielded films whose Delta Ts degraded by similar to 10% during the cycling, and a lower value of p(tot) led to dark films with only marginal electrochromism. Hence our work delineates a pathway towards W oxide films with excellent durability of the EC properties.
42.	Atapour, Masoud, et al. (author) Corrosion and metal release investigations of selective laser melted 316L stainless steel in a synthetic physiological fluid containing proteins and in diluted hydrochloric acid 2020 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 354 Journal article (peer-reviewed)abstract The corrosion and metal release characteristics of additively manufactured stainless steels are key factors for their applicability in biomedical applications. The effect of building direction on the microstructure, corrosion behavior and metal release of selective laser melted (SLM) AISI 316L stainless steel were therefore investigated in a protein-rich synthetic body fluid (PBS+BSA, pH 7.3) and in diluted hydrochloric acid (HCl, pH 1.5). A multi-analytical approach was applied to characterize SLM 316L surfaces printed in different building directions (denoted XY and XZ) and a post heat treated SLM surface (XZ-HT) compared with wrought surfaces. All SLM specimens revealed an austenitic microstructure without any amounts of delta-ferrite and without large-angled grain boundaries in contrast to the wrought 316L surface. The building direction strongly affected the grain size distribution due to the temperature gradients in the melt pools. The SLM 316L specimens released initially slightly less Fe, Cr and Ni compared with the wrought 316L specimen. Slightly less metal was released from the heat treated SLM specimen (XZ-HT) specimen compared to the other SLM specimens. Relatively high amounts of released Cr were observed in PBS+BSA, most probably attributed to protein-bound Cr, whereas substantially more Ni was released in HCl compared to PBS+BSA due to pitting corrosion and a reduced surface oxide thickness. The surface oxide composition of as-printed SLM specimens was strongly dependent on the building direction and the post heat treatment, whereas no differences were observed after abrasion either among the SLM specimens or compared with the wrought 316L specimen. Cr became in all cases enriched within the outermost surface oxide in PBS+BSA and strongly enriched in the HCl solution, coupled to a strongly reduced amount of released metals with time. The heat treated SLM specimen (XZ-HT) gained a superior charge transfer resistance, the lowest passive current density, and the highest OCP value among all specimens. In HCl, the SLM specimens showed a lower pitting susceptibility compared to the wrought specimens. No pitting was observed in PBS+BSA. No differences in corrosion or metal release characteristics were observed related to the building direction of abraded SLM specimens.
43.	Atapour, Masoud, et al. (author) Stainless steel in simulated milk and whey protein solutions - Influence of grade on corrosion and metal release 2020 In: Electrochimica Acta. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0013-4686 .- 1873-3859. ; 331 Journal article (peer-reviewed)abstract Reactions at the biointerfaces between stainless steel and protein-rich dairy products, which contain whey proteins, are important to consider in terms of food safety and material grade selection. Changes in corrosion behavior, metal release, and surface composition of austenitic (AISI 316 L), ferritic (AISI 430), and lean duplex (LDX 2101) stainless steels in simulated milk (SMS) and whey protein solution were investigated. The amount of released metals and the corrosion susceptibility increased according to 2101 < 316 L < 430. All grades revealed low corrosion rates in the whey protein solution without any sign of active/metastable corrosion. Pitting corrosion was evident for 430 in SMS. The total amount of released metals (iron, chromium, and nickel) was significantly higher in whey protein solution compared with SMS. This suggests the metal release process to be mainly governed by complexation reactions. Nickel was preferentially released compared to its bulk composition fraction for both 316 L and 2101 in the highly complexing SMS. Reduced metal release rates with time correlated with the enrichment of chromium in the surface oxide. The extent of metal release was for all metals substantially lower than release limits of metals stipulated in health regulations related to the use of alloys and metals in food-related environments.
44.	Aung, Soe Ko Ko, et al. (author) Reduced hysteresis and enhanced air stability of low-temperature processed carbon-based perovskite solar cells by surface modification 2023 In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 443 Journal article (peer-reviewed)abstract Low temperature processed carbon-based perovskite solar cells (C-PSCs) have gained great interest because of low cost and ease of fabrication. By replacing the Au electrode with carbon, stable solar cells suited for mass-production process can be made. However, power conversion efficiencies (PCEs) of C-PSCs still lag behind that of PSCs with Au contact.Here we explore low temperature (<= 150 degrees C) processed C-PSCs with, where a two-step method is used to prepare mixed-ion lead perovskite films, with tin oxide (SnO2) electron transport layer, poly(3-hexylthiophene-2,5-diyl) (P3HT) hole transport layer and carbon electrode, resulting in devices with a PCE of 14.0%. Moreover, hexyl trimethylammonium bromide (HTAB) was introduced to improve the interface between perovskite and P3HT. Perovskite grains were remarkably enlarged into micrometer-size and defects were reduced. As a result, a champion PCE of 16.1% was obtained, mainly due to enhanced fill factor from 0.67 to 0.73. The interface modification by HTAB molecule is an effective way to passivate the perovskite defects and facilitate the carrier transport at the perovskite/HTL interface. Unencapsulated devices showed excellent stability over 1500 h stored under ambient air (relative humidity -50 +/- 10%).
45.	Ayagou, Martien, et al. (author) Electrochemical impedance spectroscopy of iron corrosion in H2S solutions 2018 In: Electrochimica Acta. - : Elsevier Ltd. - 0013-4686 .- 1873-3859. ; 282, s. 775-783 Journal article (peer-reviewed)abstract Corrosion of iron exposed to H2S saturated solution at pH 4 was studied by electrochemical impedance spectroscopy, weight loss coupons and surface analysis. Hydrogen permeation was also used as indirect means of evaluating the intensity of the proton reduction reaction leading to hydrogen entry into the metal. Since corrosion in this type of test solution results in the rapid build-up of a conductive and highly porous iron sulfide scale, a specific contribution of the film has to be considered. An impedance model was thus proposed. The faradaic anodic impedance consists of a two-step reaction with charge transfer and adsorption – desorption. An additional contribution, associated with the conductive and highly porous iron sulfide film was added in parallel. This contribution, mostly visible in the low frequency domain, presents a 45° tail associated with a porous electrode behavior. This model was well adapted to describe impedance diagrams measured at various exposure times, up to 620 h. Charge transfer resistance determined from impedance analysis allowed calculating the evolution with time of the corrosion current density. A very good correlation was found between this corrosion current density and the hydrogen permeation current density. As expected in our experimental conditions, a permeation efficiency close to 100% is demonstrated. Corrosion rate of 490 μm/year was measured by weight-loss specimens, confirming the validity of the impedance analysis, which resulted in a calculated corrosion rate of 530 μm/year.
46.	B. Araujo, Rafael, et al. (author) Elucidating the role of Ni to enhance the methanol oxidation reaction on Pd electrocatalysts 2020 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 360 Journal article (peer-reviewed)abstract Amongst promising available technologies enabling the transition to renewable energy sources, electrochemical oxidation of alcohols, in a direct fuel cell or in an electrolysis reaction (H-2 production), can be an economically and sustainable alternative to currently used technologies. In this work, we highlight the advantages of a Pd-Ni bimetallic electrocatalyst for methanol electrooxidation - a convenient choice due to the low cost of Ni combined with the observed acceptable catalytic performance of Pd. We report a synergistic effort between experiments and theoretical calculations based on density functional theory to provide an in-depth understanding - at the atomistic level - of the origin of the enhanced electrochemical activity of methanol electrooxidation using the bimetallic catalysts Pd3Ni and PdNi over pure Pd. Cyclic voltammograms and High-Performance Liquid Chromatography (HPLC) demonstrate higher activity towards methanol electrooxidation with increased Ni concentration and, furthermore, higher selectivity for CO2. These effects are understood by: 1) changes in the methanol oxidation reaction mechanism. 2) Mitigation or suppression of CO poisoning on the Pd-Ni alloys as compared to the pure Pd catalyst. 3) A stronger tendency towards highly oxidized intermediates for the alloys. These findings elucidate the effects of a bimetallic electrocatalyst for alcohol electrooxidation as well as unambiguously suggest PdNi as a more cost-effective alternative electrocatalyst.
47.	Bagheri, Narjes, et al. (author) Combination of Asymmetric Supercapacitor Utilizing Activated Carbon and Nickel Oxide with Cobalt Polypyridyl-Based Dye-Sensitized Solar Cell 2014 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 143, s. 390-397 Journal article (peer-reviewed)abstract 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.
48.	Bagheri, Narjes, et al. (author) Physicochemical identity and charge storage properties of battery-type nickel oxide material and its composites with activated carbon 2016 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 194, s. 480-488 Journal article (peer-reviewed)abstract 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.
49.	Bajracharya, Suman, et al. (author) Nature inspired catalysts: A review on electroactive microorganism-based catalysts for electrochemical applications 2024 In: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 488 Research review (peer-reviewed)
50.	Bayrak Pehlivan, Ilknur, et al. (author) Ion conduction mechanism of nanocomposite polymer electrolytes comprised of polyethyleneimine–lithium bis(trifluoromethylsulfonyl)imide and silica 2014 In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 119, s. 164-168 Journal article (peer-reviewed)

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