[en] The effect of various parameters on the yield for the electrochemical generation of ferrate was investigated for pressed pellet iron electrodes. An optimum yield was observed for a NaOH concentration of 14-16 M of the anolyte. The rate of iron dissolution and generation of ferrate increased when the temperature of the electrochemical cell is raised from room temperature to 50 deg. C. The pressure applied to the iron powder during the formation of the pellet electrode did not have a strong influence on ferrate generation, at least in the range investigated in this work (5-8 ton/cm²). On the other hand, the purity, particle size and packing density of the powders are important factors in determining the current yield for ferrate generation and the maximum yield was not obtained with the smallest particles investigated (<10 μm). An optimum yield for ferrate generation of 60% was observed for a 2 h electrolysis. The surface of the pressed pellet iron electrode was also analyzed following the electrolysis in 14 M NaOH by X-ray diffraction and X-ray photoelectron spectroscopies. The electrogenerated ferrate was not detected at the electrode surface but the presence of various iron oxides and sodium carbonate was evidenced by these techniques

[en] For more than two decades, electrochemical electricity storage devices have started their organic revolution. Pseudo-supercapacitors, redox supercapacitors and 'all-organic' hybrid devices have already conquered the scientific and industrial communities, even if major efforts are still needed to improve their performance and stability in order to be able to integrate them permanently into long-lasting structures (aeronautics, automotive, building, etc.). A recent strategy consists in grafting small electroactive molecules on the surface of activated carbons. The assembly of these highly scalable generic elements leads to a very large number of possible combinations and rules must be respected for the grafting to be beneficial. This article presents the contributions and limitations of the grafting strategy and concludes with an original alternative to grafting molecules onto carbon

[en] We report the synthesis of a new composite electrode based on nanosized-manganese oxide and carbon nanotubes (CNTs) by electrophoretic deposition of CNTs on a stainless steel (SS) substrate followed by direct spontaneous reduction of MnO₄^- ions to MnO₂ to form the multi-scaled SS-CNT-MnO₂ electrode. The resulting material was characterized by scanning electron microscopy, energy dispersive X-ray analysis, cyclic voltammetry and galvanostatic charge-discharge in a 0.65 M K₂SO₄ aqueous solution. The binderless SS-CNT-MnO₂ nanocomposite electrode shows a very high specific capacitance of 869 F/g of CNT-MnO₂ and good stability during long galvanostatic charge-discharge cycling. To the best of our knowledge, this is one of the highest capacitance for manganese oxide electrode ever reported. In addition to its applicability in electrochemical capacitors, this methodology could be extended to develop other high performance nanocomposite material electrodes based on carbon nanotubes and metal oxide for the future generation of electrochemical power sources.

[en] The modification of glassy carbon electrode was achieved by electrochemical reduction of in situ generated diazonium cations in acetonitrile. The in situ generation of 4-nitrophenyl diazonium cations in acetonitrile was investigated by spectroscopic methods. UV-visible spectroscopy revealed slow kinetics for the reaction of 4-nitroaniline with tert-butylnitrite in acetonitrile to form the corresponding diazonium cation. As a result, a coupling reaction, which implies a consumption of the amine and loss of the already formed diazonium cations, was evidenced by ¹H NMR spectroscopy. This spectroscopic study allowed the optimization of the in situ diazonium cations generation prior to the modification step. The electrochemical modification of the carbon electrodes with 4-nitrophenyl, 4-bromophenyl and anthraquinone groups was characterized by cyclic voltammetry and the resulting grafted layer were characterized by electrochemical techniques. The cyclic voltammetric behaviour during the electrochemical grafting was very similar to the one observed for an isolated diazonium salt dissolved in acetonitrile. In the case of the anthraquinone-modified electrode, the use of acetonitrile, into which the corresponding amine is soluble but not in aqueous media, allowed for its grafting by the in situ approach. The barrier properties of these grafted layers are similar to those obtained from isolated diazonium salts. Finally, the chemical composition of the grafted layers was determined by X-ray photoelectron spectroscopy and surface coverage in the range 5-7 x 10^-10 mol cm^-2 was estimated for films grown in our experimental conditions

[en] The present work is dealing with the attachment of D-glucosaminic acid (D-GA) on glassy carbon electrode by two different methods. Firstly, the electrode was modified by chloromethylphenyl groups by reduction of 4-chloromethylphenyldiazonium cations followed by the nucleophilic substitution of the chlorine by the amine functionality of D-GA and secondly by the direct immobilization of the amine terminated molecule. The generality of the nucleophilic substitution reaction and the direct immobilization of an amine were also demonstrated with reactants bearing an electroactive ferrocene moiety; 4-nitrophenylferrocene (NFc) and 4-ferrocenylaniline (FcA). The surfaces modified with FcA and NFc were investigated by cyclic voltammetry, and the D-GA modified electrodes were characterized by X-ray photoelectron spectroscopy. A preliminary evaluation of the efficiency of these surface modifiers to prevent protein adsorption was realized by scanning electron microscopy.

[en] The electrodeposition of copper on pyrolytic graphite from CuSO₄ or Cu(NO₃)₂ in a 1.8 M H₂SO₄ aqueous solution was investigated. The Cu deposits were formed potentiostatically and characterized by electrochemical methods, scanning electron microscopy, energy dispersive X-ray and X-ray photoelectron spectroscopy. It was found that the deposition of copper in the presence of CuSO₄ induced the codeposition of sulfate anions. In addition, electrochemical quartz crystal microbalance revealed that the increase of the Cu mass was higher than expected from Faraday's law with the CuSO₄/H₂SO₄ solution. These results confirmed the specific adsorption of anions during the Cu deposition. On the other hand, the use of Cu(NO₃)₂ resulted in a non-contaminated surface with different surface morphologies. The Cu nuclei size, the population density and the surface coverage were monitored as a function of the deposition potential. From the analysis of the chronoamperometric curves, the nucleation kinetics was studied by using various theoretical models. Independently of the Cu source, the nucleation mechanism follows a three-dimensional (3D) process. Copper nucleates according to an instantaneous mode when the deposition potential is more negative than -300 mV versus Ag/AgCl, while the nucleation was interpreted in terms of a progressive mode at -150 mV. The nuclei population densities were also determined by using two common fitting models for 3D nucleation and growth (Scharifker-Mostany and Mirkin-Nilov-Heerman-Tarallo). Their values are reported here as a function of the deposition potential

[en] Lead dioxide thin films were electrodeposited on gold substrates and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mass change occurring upon immersion in a H₂SO₄ electrolyte and during electrochemical reduction was observed in situ by electrochemical quartz crystal microbalance (EQCM). A hydrated PbO₂ gel-type layer is formed at the surface of electrodeposited PbO₂. The concentration of the H₂SO₄ electrolyte does not affect the composition of the gel nor the amount of lead dioxide involved in the hydration process. It is established that 1.3 x 10^-7 mol cm^-2 of β-PbO₂ are hydrated at the surface of an electrodeposited film and that the hydration reaction occurs according to the following reaction: PbO₂^(crystal) + xH₂O ↔ (PbO(OH)₂.(x - 1)H₂O)^(gel), where x = 8.1. The mass change occurring during the first and subsequent discharge of PbO₂ was recorded. It is shown that both PbO₂^(crystal) and PbO(OH)₂.(7.1)H₂O)^(gel) are reduced to PbSO₄ during the first discharge.

[en] Supercapacitors are new storage elements for electrical energy. They have an instantaneous power more significant than that of the batteries and an energy larger than that of the conventional capacitors. Their lifespan are higher than that of the batteries (approximately 10 years). They have a structure anode-cathode containing activated carbon, which leads to obtain very high capacitance values (up to 5000 F). So supercapacitors will be new potential storage elements for energy, ideally complementary to the batteries or the fuel cell in the field of transport for example. Other applications as in the field of stationary or telecommunication were carried out in the world, or are in phase of study and of evaluation. Many studies are carried out to increase the cross capacity-voltage of these components. However due to their recent technology, some significant points remain in order to know how to improve the reliability of the component and the system in which they are used. The objective of this congress is to bring together in Europe the specialists who work in the field of the supercapacitors, to present the state of the art and to discuss the evolution of the technologies for supercapacitors, as well as theirs use in various fields. This congress will have to specify the problems concerning reliability, the diagnosis and the safety of their use as well as the development of devices for balancing and power electronics related to the use of the supercapacitors. Content: 1 - Ultracapacitors: today's achievements and tomorrow's perspectives; 2 - Energy Storage on board of railway vehicles; 3 - Nanostructured transition metal oxides for aqueous hybrid electrochemical supercapacitors; 4 - Development and fabrication of a 1.5F-5V Solid electrolyte supercapacitor; 5 - Study of surface treatment of Al current collector foil and influence of carbon nanotubes in Carbon/Carbon supercapacitors in organic electrolyte; 6 - Calculation of diffusion coefficients of TEABF4 in acetonitrile by means of the single particle microelectrode technique; 7 - Fe₂O₃ polypyrrole hybrid nanocomposite supercapacitors; 8 - Manganese oxide nanocomposites as supercapacitor electrode materials: Preparation and electrochemical performances; 9 - Fabrication of Birnessite-type Layered Manganese Oxide Films for Supercapacitors; 10 - Electro-thermal analysis of hybrid electrochemical Supercapacitors; 11 - Development and characterization of Ni-C supercapacitor; 12 - Electrical and thermal behaviour of a supercapacitor module: on-line characterization; 13 - Ultracapacitor electrical modeling using temperature dependent parameters; 14 - Modeling of the supercapacitors and influence of the temperature during a self-discharge; 15 - Supercapacitor modeling with Artificial Neural Network (ANN); 16 - First accelerated ageing cycling test on supercapacitors for transportation applications: methodology, first results; 17 - Impedance measurement and modeling of supercapacitors for railway applications; 18 - Capacitance and series resistance determination in high power ultracapacitors; 19 - Contribution to dimensioning a pack of supercapacitors for 12/42 V application; 20 - Using supercapacitors in combination with bi-directional DC/DC converters for active load management in residential fuel cell applications; 21 - The use of a combined battery/supercapacitor storage to provide voltage ride-through capability and transient stabilizing properties by wind turbines; 22 - Power-energy management in lift drive system with super capacitors compensator; 23 - A solution for increasing the efficiency of Diesel-electric locomotives with supercapacitive energy storage; 24 - System variants for operation of trams without a catenary; 25 - Supercapacitors as an energy storage for fuel cell automotive hybrid electrical system; 26 - Supercapacitors for embarked systems as a storage energy device solution; 27 - Small Hybrid Bus TOHYCO-Rider with Supercaps and inductive power transfer; 28 - Fostering the commercialization of Ultracapacitors