Silica/polypyrrole nanocomposites without dopant (SiO2/PPy) and with oxalate dopant (SiO2/PPyOx) were synthesized using polymerization of pyrrole in the presence of nano SiO2. Synthesized SiO2/PPy and SiO2/PPyOx were characterized by FTIR, SEM, TEM and EDX and their electrical conductivities were determined by CV method through the two-point-electrode without electrolyte. The corrosion protection performance of polyvinylbutyral (PVB) coatings containing SiO2/PPyOx was evaluated and compared with that of pure PVB coatings and of PVB coatings containing SiO2/PPy by electrochemical impedance spectroscopy and adhesion measurement. The results show that electrical conductivities of SiO2/PPy and SiO2/PPyOx were 0.181 and 0.109 S/cm, respectively. The ratio of PPy on SiO2 in SiO2/PPy and SiO2/PPyOx composites was 0.77/1 and the ratio of oxalate on PPy in SiO2/PPyOx composite was 1.24/1. SiO2/PPy and SiO2/PPyOx improved corrosion resistance and adhesion of PVB coatings. The presence of oxalate in SiO2/PPyOx significantly enhanced the effect of SiO2/PPy on the protection performance of PVB coatings.

Fluorine is produced from the electrolysis of KF/HF mixtures at around 95°C. In the cell configuration, carbon anodes are screwed onto a copper busbar. Much attention has been paid to the stability of copper since the corrosion and redeposition of this metal on the cathodes is one of the main factors (side reaction) that limit the production yield of fluorine gas, the lifetime of the cells, and the development of new electrolyzers. Therefore, in the frame of this study, various experiments were carried out to determine the corrosion rate of copper for a wide range of HF ratios and temperatures. A statistical approach to the electrochemical data allowed us to predict the corrosion rate for many of the operating conditions. At open circuit voltage (OCV), copper shows good corrosion resistance even for high HF ratios. However, under 6-V anodic polarization, copper corrosion rate increases drastically with an increase of the temperature and/or the HF ratio. Characterization techniques have shown that only a thin copper fluoride layer has been detected on copper at OCV. By contrast, two types of copper fluorides were evidenced at the electrode surface (CuF2 and KCuF3) when a potential was applied to Cu. Under anodic polarization, a thin CuF2 layer is formed at the copper surface, whereas KCuF3 is detected on the electrode surface resulting from the precipitation of Cu2+. For a better interpretation of the results, erosion–corrosion phenomenon emanating from the fluorine bubbles' impacts and electrolyte movements have been highlighted by weight losses of copper pieces. The breakdown of the passivation layer on copper and the exposition of the surface to the corrosive medium imply a quicker degradation of the metallic pieces.

Boron doped diamond microelectrodes arrays (MEA) have been prepared in order to be used as new amperometric sensors in electrochemical cells for HPLC detectors. The following parameters were studied: number and diameter (15–40µm) of the electrodes, distance between them (50–240µm), and effect of the flow rate (0.1–3mL/min). It was thus possible to find the optimum value of the parameters which give a good signal/noise ratio in the chronoamperometric responses, with a size of the electrochemical sensors as small as possible.

Sodium-hydroxyapatite coatings (NaHAp) were electrodeposited on the surface of CoNiCrMo alloys (NaHAp/CoNiCrMo) from an electrolyte solution containing Ca(NO3)2, NH4H2PO4 and NaNO3. The phase structure, composition and morphology of the coatings were studied by X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX) and Scanning electron microscopy (SEM). The results showed that the obtained coatings were single phase crystals of HAp, with plate shape and that the sodium acts as a doping element in their composition (0.73%). The deposition temperature affected the thickness as well as the phase structure of the coatings. When the deposition temperature increased, the thickness of the coating increased. The XRD results showed that the coating obtained at 50°C was composed of single phase crystals of HAp with the thickness 6.34m. The in vitro test with CoNiCrMo and NaHAp/CoNiCrMo materials in SBF solution was realized with different immersion times. The results showed that the pH of SBF decreased and the mass of materials increased. SEM images prove the formation of apatite on the surface of NaHAp/CoNiCrMo leading to the decrease of the corrosion current density during immersion process in SBF solution.

The deposition of TiN on stainless steel substrates may improve the stability and compatibility of this material with bone, which may be advantageously exploited for the elaboration of advanced pros- thetic devices. In this work, TiN-coated 316LSS (by way of DC magnetron sputtering) was used as a starting material for investigating the electrochemical post-deposition of hydroxyapatite (HAp) which has a composition close to that of bone. Electrodeposition was carried out starting from an aqueous medium containing solubilized Ca(NO3)2 and NH4H2PO4 in the presence of H2O2. We report the influence of experimental conditions on the morphology of the obtained HAp coating on TiN/316LSS. The effect of applied potential, temperature, H2O2 concentration, pH and duration of reaction were thoroughly discussed on the basis of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy and Energy Dispersive X-ray Spectroscopy (EDX) results. This method appears advantageous for producing HAp-coated implant materials.

Pierre Turq has made decisive contributions to the theory and to the multiscale simulation of charged systems, such as molten salts, electrolyte solutions and colloidal suspensions, in the bulk, at interfaces and under confinement. His research line focussed on dynamical properties and was characterised by constant efforts to connect his theoretical work to both experiments and practical applications. In this article, his colleagues and former students pay a tribute to his past and current research interests by illustrating some recent developments accomplished in his laboratory.

Lead dioxide deposits have been prepared as thin films Fluorine-doped tin oxide (FTO) substrates from methanesulphonate or nitrate-based plating solutions. The resulting electrodes exhibit lower oxygen evolution overpotential than FTO and their flatband potential is considerably higher. In addition, it is possible to increase their donor density by incorporating fluoride anions in the PbO2 coating.The electrodes have been designed for the generation of oxygen. It is shown that a transparent electrocatalytic FTO/PbO2 thin film assembly can be prepared by such process. (C) 2013 Elsevier B.V. All rights reserved.

An original selective and quantitative detection method for direct access to reactive oxygen species (ROS) generated in near-neutral aqueous solutions during transient electrochemical experiments is described herein. Several chemiluminescent probes, which were selected for their high selectivity toward ROS were used and the selective electrogenerated chemiluminescence (SECL) method was validated on several electrocatalytic materials known to exhibit different behaviors toward the oxygen reduction reaction (ORR); the examined electrodes consisted of platinum, Au(1 1 1), glassy carbon and boron-doped diamond (BDD). We first selected appropriate molecular probes that are suitable for use under electrochemical polarization conditions and that are chemiluminescent in the chosen aqueous solutions. The roles of the concentration, solubility and possible activation of the molecular probes were identified. Then, the information obtained by the simultaneous recording of the amperometric signal was correlated with the chemiluminescence intensity, which was measured with a highly sensitive photomultiplier tube (PMT). The experimental results were interpreted by constructing a potential vs. pH diagram for the oxygenated species. The complementary nature of the information about the mechanistic path of the ongoing mechanism of ORR on the different electrode materials allowed us to propose a unified scheme. A coupled proton electron transfer (CPET) mechanism can be invoked to explain the major differences observed from the identified reactive intermediates in relation to the electrocatalytic activity of the electrode materials. (c) 2013 Elsevier Ltd. All rights reserved.

The overpotential of oxygen evolution reaction is 700-800 mV more positive at FTO anode than on Pt electrode.This property of FTO coating makes it attractive as an electrode material for electrochemical sensors and electroanalytical chemistry.However, oxygen transfer reactions, such as Pb 2+ and Cl -oxidation, occur with considerably lower overpotential.It indicates the possibility of formation of oxygen-containing particles which are adsorbed on the FTO surface at 1.5-1.6V vs Ag/AgCl.Similar kinetics of galvanostatic formation of hypochlorite-ions on the Pt and FTO surface can indicate the similar character, surface concentration, and the energy of adsorbed radical-type particles.FTO coating thereby shows high electrocatalytic activity towards the synthesis of sodium hypochlorite during the electrolysis of dilute NaCl solutions.The preparation of new electrodes with electrocatalytic properties toward oxidation reactions was performed by electrodeposition of lead dioxide onto glass substrates covered with FTO.The modification of FTO electrodes with PbO 2 leads to more conductive electrodes with an improved donor density.The electrodes have been designed for oxygen generation.

Composite materials based on PbO2 containing TiO2 or ZrO2 were prepared from electrolytes containing a suspension of TiO2 or ZrO2. The contents of foreign oxides in the composite depend on the electrolyte composition and conditions of deposition. When a dispersed phase is incorporated into the composite coating, the dimensions of lead dioxide crystals decrease to submicro- and nano-size. Physico-chemical properties of composite materials are mainly determined by their chemical composition. (C) 2011 Elsevier B.V. All rights reserved.

Composite materials based on PbO2 containing TiO2 or ZrO2 were prepared from electrolytes containing a suspension of TiO2 or ZrO2. The contents of foreign oxides in the composite depend on the electrolyte composition and conditions of deposition. When a dispersed phase is incorporated into the composite coating, the dimensions of lead dioxide crystals decrease to submicro- and nano-size. Physico-chemical properties and electrocatalytic activity of composite materials are mainly determined by their chemical composition. The electrocatalytic properties of a composite PbO2-TiO2 anode vs the oxygen evolution reaction (OER) and the electrochemical degradation of methyl tert-butyl ether (MTBE) were investigated.

Electrochemical behavior of 316L stainless steel material according to immersion time in simulated body fluid solution was studied by measurement of open circuit potential (Eo), Tafel polarization and electrochemical impedance methods. The increase of both Eo and Rp, while the decrease of icorr showed the formation of apatite film on the surface of 316L stainless steel in test time. The results of measurement infrared IR spectra, SEM, X-ray and EDX indicated that the formation of apatite film was relatively thick after 17 days immersion and characterized the structure of HAp

In this work, the electrogeneration of peroxodisulfate from a 1 M H2SO4 solution on boron-doped diamond microelectrodes array has been studied. The peroxodisulfate is detected at the vicinity of the boron doped diamond electrode, with the SECM probe, only when the polarization of the microarray is greater than 2.1 V versus AgCl/Ag. The main electrochemical interest of working with microarrays comes from the fact that current densities and efficiencies are comparable to those observed in the peroxodisulfate industrial production. The local Scanning Electrochemical Microscopy studies have shown that the peroxodisulfate reaction is related to a surface mediated oxidation of sulfate anions into peroxodisulfate according to a complex reactional mechanism.

Titanium is a valve metal able to withstand corrosion due to the presence of a passivating layer of titanium oxide on its surface But due to that more or less insulating layer titanium cannot be used directly as an anodic material However modification of the surface of a Ti/TiO2 substrate may lead to the formation of new structures Ti/TiO2/M or Ti/TiO2/OX in which M is a metal such as platinum and OX a conducting oxide exhibiting electrocatalytic properties These structures have interesting electrochemical properties and may be used as efficient electrode materialsIn this paper after a review of the electrochemical behaviour of these structures we give new results concerning the selective electrodeposition of lead dioxide on Ti/TiO2 substrates and we propose an interpretation of the results taking into account the dielectric properties of the underlying TiO2 It is shown that there is a dramatic decrease of the resistance of the electrode when a PbO2 layer is electrodeposited onto a Ti/TiO2 structure That effect allows the preparation of electrodes (low-cost DSAs) that may be used as anodes in spite of the presence of the underlying TiO2 layer that layer being useful to avoid corrosion of the titanium substrate At last the effect of stabilization of the underlying TiO2 layer is discussed (C) 2010 Elsevier Ltd All rights reserved

In the work, the regularities of electrodeposition of composite materials based on PbO2 containing the valve metal particles are considered. The content of dispersed phase in the composite depends on the electrolyte composition and conditions of deposition. The incorporation of titanium particles into PbO2 considerably changes the deposit morphology. It is found that the service life of electrodes containing dispersed Ti phase increases by 4 times as compared with the conventional anodes made of pure PbO2.

During the electrolysis of molten KH-2HF, a solid CF film is formed on carbon anodes. The influence of the potential applied to the anode on the composition of the CF surface film was studied by XPS and NMR. Results obtained with carbon electrochemically passivated in molten KF-2HF have been compared with those obtained with carbon simply immersed in molten KF-2HF without any polarization. Whatever the potential, and even in the case of carbon sample immersed in molten KF-2HF without any polarization, the presence of covalent and semi-ionic C–F bonds has been pointed out both by XPS and NMR. For polarized samples, the higher the potential applied to the anode in KF-2HF, the higher the fluorination level. From investigations carried out with carbon activated at 40V in molten KF-2HF, it was concluded that the electropolishing of the surface induced by this treatment allows enhancing drastically the fluorine evolution reaction.

Electrodeposition of composite PbO2-based materials containing titanium dioxide particles was studied. The TiO2 content of the composite depends on the bath composition and the deposition conditions. Inclusion of TiO2 particles in PbO2 substantially changes the morphology and structure of the deposit. The oxygen overpotential at composite materials increased but the rate of the conversion of 4-chlorophenol into nontoxic compounds remained virtually unchanged. The lifetime of the electrodes containing the inert TiO2 phase was found to be twice as long as that of traditional PbO2 anodes.