Fluorine-doped tin oxide (FTO) electrodes were functionalized by electro reduction of in situ generated 4-carboxyphenyl diazonium salt. Several grafting potentials and times were investigated in order to find the optimal grafting conditions. The electrochemical behavior of bare FTO electrodes in the presence of the diazonium, together with Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) characterization of the grafted electrodes in the presence of redox probes ferricyanide and ferrocene allowed us to conclude that 10 min grafting under a controlled potential of -0.50 V lead to the formation of a poorly-packed organic multilayer on the electrode surface. X-ray Photoelectron Spectroscopy (XPS), together with Fourier-Transform Infrared Spectroscopy (FTIR) analyses, further evidenced the presence of carboxylic groups onto modified FTO electrodes.

Cet article présente l'utilisation réussie de films minces électrodéposés de birnessite, un matériau non toxique à base d'un élément abondant, en tant que matériau d'électrode pour le développement d'un traitement électrochimique simple, efficace, peu onéreux et facile à mettre en œuvre dans des conditions très douces, pour dégrader et minéraliser des polluants organiques. L'idée originale consiste à coupler les propriétés oxydantes naturelles de la birnessite à un traitement d'oxydation électrochimique dans le but d'augmenter ses capacités de dégradation. Deux polluants pertinents ont été testés. Le glyphosate (N-(phosphonométhyl) glycine) est le principe actif du Roundup(r), un herbicide à large spectre le plus utilisé dans le monde. En raison de cette utilisation intensive, le glyphosate est un des pesticides le plus retrouvé dans l'environnement. L'AMPA (acide aminométhylphosphonique) est le principal métabolite du glyphosate, plus toxique et persistant que son parent. Ce composé peut provenir aussi de la dégradation des acides phosphoniques présents dans les détergents, et c'est pourquoi l'AMPA se retrouve également très fréquemment dans l'environnement, notamment en milieu urbain, et très récemment en milieu marin. De très bonnes capacités de minéralisation ont été obtenues pour ces deux polluants (0,720 g glyphosate minéralisé / g birnessite ; 0,105 g AMPA minéralisé / g birnessite) à des coûts énergétiques très bas, ce qui permet d'envisager des applications potentielles pour des traitements soit à des concentrations de niveau environnemental en complément de traitements existants, soit directement à la source de pollution.

Numerical modelling is an effective tool for predicting corrosion. We make use of a stochastic Cellular Automata (CA)-based modelling for corrosion studies at a mesoscopic scale. Physico-chemical phenomena that cannot be satisfactorily described by standard deterministic and macroscopic methods are here taken into account. In this CA modelling, materials and their environments are described by a 3D lattice, where each cell has a state. The physico-chemical phenomena are represented as simple rules that define the temporal evolution of the states of the cells. These rules can be combined to model complex systems. Our model is stochastic in the sense that the transition rules are given probabilities and diffusion in the electrolyte is modelled as a random walk. Simultaneous anodic and cathodic reactions describe the corrosion mechanisms. Special emphasis is given to the electric connection between the anodic and cathodic cells. The anodic and cathodic reactions occur simultaneously, maintaining the electric balance. In this work, we study the evolution of the generalised corrosion of a metallic surface. Two regimes are found that are determined by local acidity of the electrolyte. Uniform corrosion is predominant in the first regime, where anodic and cathodic half-reactions occur homogeneously over the surface. In the second regime, a local increase in acidity appears that induces the predominance of localised corrosion. The competition between these two regimes determines the global corrosion kinetics.This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems.

We present a stochastic CA modelling approach of corrosion based on spatially separated electrochemical halfreactions, diffusion, acido-basic neutralization in solution and passive properties of the oxide layers.Starting from different initial conditions, a single framework allows one to describe generalised corrosion, localised corrosion, reactive and passive surfaces, including occluded corrosion phenomena as well.Spontaneous spatial separation of anodic and cathodic zones is associated with bare metal and passivated metal on the surface.This separation is also related to local acidification of the solution.This spontaneous change is associated with a much faster corrosion rate.Material morphology is closely related to corrosion kinetics, which can be used for technological applications.

An all covalent nanostructured lead sensor was built by the successive grafting of gold nanoparticles and carboxylic ligands at the surface of self-adhesive carbon screen-printed electrodes (SPEs). Surface analysis techniques were used in each step in order to investigate the structuration of this sensor. The self-adhesive surfaces were made from the electrochemical grafting of p-phenylenediamine at the surface of the SPEs via diazonium salts chemistry. The quantity of grafted aniline functions, estimated by Nuclear Reaction Analysis (NRA) performed with p-phenylenediamine labelled with N-15 isotope, is in agreement with an almost complete coverage of the electrode surface. The subsequent diazotization of the aniline functions at the surface of the SPEs was performed; X-ray Photoelectron Spectroscopy (XPS) allowed us to consider a quantitative conversion of the aniline functions into diazonium moieties. The spontaneous grafting of gold nanoparticles on the as-obtained reactive surfaces ensures the nanostructuration of the material, and XPS studies showed that the covalent bonding of the gold nanoparticles at the surface of the SPEs induces a change both in the Au-4f (gold nanoparticles) and Cl-2p (carbon ink) core level signals. These unusual observations are explained by an interaction between the carbon ink constituting the substrate and the gold nanoparticles. Heavy and toxic metals are considered of major environmental concern because of their non-biodegradability. In a final step, the grafting of the carboxylic ligands at the surface of the SPEs and an accumulation step in the presence of lead(II) cations allowed us to evidence the interest of nanostructured materials as metallic pollutants sensors. (C) 2016 Elsevier B.V. All rights reserved.

We use stochastic Cellular Automata (CA) based modelling for corrosion studies at a mesoscopic scale. Physico-chemical phenomena that cannot be satisfactorily described by standard deterministic and macroscopic methods are represented. Materials are described by a 3D lattice where each cell has a state. Phenomena are represented as simple transition rules defining the evolution of the cells with given probabilities. Diffusion in the electrolyte is modelled as a random walk. Charge transfer corresponds to simultaneous anodic and cathodic reactions with special emphasis on their electric connection ensuring electric balance. We study evolution of pitting corrosion in terms of pit size morphology and acidity of the electrolyte. Starting from metal covered by a passive layer with a single defect, a cavity starts growing inside the metal and notably the exterior basic environment delays the dissolution of the protective passive layer. Results are in accordance with published experimental results on pitting corrosion.

The presence of AMPA in environment becomes today a real problem due to its persistence, its toxicity, and its multiple origins (main metabolite of glyphosate, the pesticide the most used in the world; degradation product of personal care and industrial products). This paper reports the development of a simple, effective, cheap and easy electrochemical treatment, for mineralising AMPA under very soft conditions: at room temperature, at free pH, and in a classical open electrochemical cell. The electrode material used is an electrodeposited thin film of birnessite, a non-toxic material, synthesised in very soft conditions. The original idea is to couple the spontaneous oxidative properties of birnessite to an electrochemical oxidation treatment in the aim to increase its reactivity towards this pollutant. Very good mineralisation rates and capacity (≈0.115g AMPA mineralized by gramme of birnessite) were obtained with very low energy supplies (Q≈3C). Some tests performed with concentrated glyphosate solutions, one of its main parents, give also good results allowing us to envisage the development of an easy method of wastewater treatments at very low costs in complement of classical methods and/or directly at the source of pollution.

INTRODUCTION The increase in industrial and agricultural activities in developing countries requires the use of high quantities of synthetic chemicals such as pesticides, insecticides, dyes and chemical additives. Many industries, including textiles, use various dyes and generate a considerable amount of colored wastewater causing damage to the ecological system[1-3]. Moreover, most dyes are stable to light and are not biodegradable[4,5], that is why the dyes in BIRNESSITE ELECTRODEPOSITED ONTO SnO2SUBSTRATE: APPLICATION TO THE REMOVAL OF METHYL ORANGE

We present a stochastic three dimensional (3D) model for corrosion at a mesoscopic scale. The competition between uniform and localized corrosion is studied, with special emphasis given to the connection between the anodic and cathodic reactions. Even if the reactions happen at different places, they are linked and occur simultaneously, maintaining an electric balance. We focused on the particular case of an occluded corrosion on a metal covered by a non reactive layer, where two growth regimes are evidenced and controlled by the diffusion of species in the electrolyte. (C) 2016 Elsevier Ltd. All rights reserved.

Laccase in combination with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as a mediator is a well-known bioelectrocatalyst for the 4-electron oxygen reduction reactions (ORR). The present work deals with the first exploitation of mesoporous iron(III) trimesate-based metal organic frameworks (MOF) MIL-100(Fe) (MIL stands for materials from Institut Lavoisier) as a new and efficient immobilization matrix of laccase for the building up of biocathodes for ORR. First, the immobilization of ABTS in the pores of the MOF was studied by combining micro-Raman spectroscopy, X-ray powder diffraction (XRPD), and N2 porosimetry. The ABTS-MIL-100(Fe)-based modified electrode presents excellent properties in terms of charge transfer kinetics and ionic conductivity as well as a very stable and reproducible electrochemical response, showing that MIL-100(Fe) provides a suitable and stabilizing microenvironment for electroactive ABTS molecules. In a second step, laccase was further immobilized on the MIL-100(Fe)-ABTS matrix. The Lac-ABTS-MIL-100(Fe)-CIE bioelectrode presents a high electrocatalytic current density of oxygen reduction and a reproducible electrochemical response characterized by a high stability over a long period of time (3 weeks). These results constitute a significant advance in the field of laccase-based bioelectrocatalysts for ORR. According to our work, it appears that the high catalytic efficiency of Lac-ABTS-MIL-100(Fe) for ORR may result from a synergy of chemical and catalytic properties of MIL-100(Fe) and laccase.

We report in this paper an original way to covalently bind the macrocyclic ligand, 1,4,8,11-tetraazacyclotetradecane (cyclam), through diazonium salt chemistry, on the surface of carbon screen-printed electrodes (SPEs). The in situ synthesis of the diazonium salt obtained from the amine precursor derived from the cyclam and its electrografting are described. X-ray Photoelectron Spectroscopy was used to characterize this functionalized surface. Owing to the strong cyclam–Cu(II) affinity, the so called SPE-cyclam can be used as electrochemical sensors for Cu(II) determination at trace levels. The influence of electroanalysis parameters such as the accumulation time and the pH of the medium were investigated. An interference study was carried out with numerous metallic cations and few interference was found for Cu(II) quantification. The described method provided a limit of detection and a limit of quantification of 1.3×10−8M and 4.0×10−8M, respectively. Interference study and performances show that SPE-cyclam could be considered as efficient sensors for environmental analysis.

This work presents the synthesis and the characterization of hybrid material thin films obtained by the combination of two processes. The electrochemical grafting of organic layers made of carboxyphenyl moieties is carried out from the reduction of a diazonium salt on tin dioxide (SnO2) thin films previously deposited on Si substrates by metal organic chemical vapor deposition (MOCVD). Since the MOCVD experimental parameters impact the crystal growth of the SnO2 layer (i.e. its morphology and its texturation), various electrochemical grafting models can occur, producing different hybrid materials. In order to evidence the efficiency of the electrochemical grafting of the carboxyphenyl moieties, X-ray Photoelectron Spectroscopy (XPS) is used to characterize the first nanometers in depth of the synthesized hybrid material layer. Then three electrochemical grafting models are proposed. (C) 2016 Elsevier B.V. All rights reserved.

Nanocomposites combining the mesoporous iron(iii) trimesate MIL-100(Fe) (MIL: Matériaux Institut Lavoisier) and platinum nanoparticles (Pt-NPs) have been used as immobilization matrices of glucose oxidase (GOx). Due to the physico-chemical properties of Pt-NPs (electroactivity) and MIL-100(Fe) (high specific surface area and pore volume, biocompatibility), the resulting GOx-MIL-100(Fe)-PtNP bioelectrode exhibits excellent electrocatalytic performances for glucose detection. This novel glucose biosensor presents a high sensitivity of 71 mA M-1 cm-2 under optimum conditions and a low limit of detection of 5 μM with low response time (<5 s). In contrast, substitution of iron by chromium or aluminum in MIL-100 leads to a much lower sensitivity and higher response time values, suggesting that the iron centres of MIL-100(Fe) may be involved in a synergistic effect which indeed enhances the catalytic oxidation of glucose and biosensor activity. Thus, this work extends the scope of MOF nanoparticles with engineered cores and surface to the field of highly sensitive, durable glucose biosensors.

Tin dioxide (SnO2) thin films are deposited by metal organic chemical vapor deposition (MOCVD) on Si substrates from three commercial metal organic precursors. The morphology and the microstructure of the films are observed by field emission gun-scanning electron microscopy (FEG-SEM). The films are dense and made of crystallites with a nanometer size. The structural properties of the films are assessed by grazing incidence X-ray diffraction (GIXRD). A tetragonal SnO2 phase is observed in the deposited thin films with various texturations as a function of the metal organic precursor used for the deposition. Chemical characterizations of the thin films are also carried out by Fourier transformed infrared spectroscopy (FT-IR) and by X-ray photoelectron spectroscopy (XPS). Finally, the observed morphological, chemical and structural modifications induce changes in the electrical properties of the film. Results are discussed and indicate that the electrical properties of the synthesized SnO2 thin films differ as a function of the MOCVD precursor used for the deposition. Therefore, their electrochemical behavior is modified which influences the grafting of organic molecules to synthesize and develop novel hybrid materials sensors.

For the first time, the assisted transfer of Pb(II) across a water/1,2-Dichloroethane (DCE) microinterface was investigated in the presence of 8-Hydroxyquinoline (named also oxine or 8-HQ) in the organic phase. A monocharged complex was formed in the aqueous phase and then transferred in the organic phase. A good relationship was obtained between currents and Pb(II) concentrations in the 10(-4) to 5 10(-3) M range and 10(-5) to 6 10(-5) M range using cyclic voltammetry and square wave voltammetry respectively. In presence of other heavy metals such as Cd(II) and Zn(II), only one electrochemical process is observed regardless of the mixture. Moreover, stationary currents increase in direct linear relation with the sum of M(II) concentrations added in water, allowing an overall detection of heavy metals. This result indicates that this method can be very interesting for monitoring all toxic metals in effluents. The limit of detection was found equal to 0.2 ppm for lead. This value allows us to reach levels significant for industrial effluents, in comparison to the limits fixed by the French ministry of ecology for lead, cadmium and zinc to 0.5 ppm, 0.2 ppm and 2.0 ppm respectively. This study highlights the real interest of devices based on a liquid-liquid microinterface. (C) 2014 Elsevier Ltd. All rights reserved.

•Confirmation of the perfect additivity of micropores independently of the geometry of arrays.•Study of assisted transfer of cadmium ions by 8-HQ at water/1,2-DCE.•Validation by cyclic and square wave voltammetry measurements for high and low concentrations.•Quantification of Cd(II) ions until 11 ppb in very simple conditions.•Highlighting of the very interesting use of arrays in a classical liquid-liquid microinterface device.

This Letter describes the fast synthesis of a mono-aminated calix[6]arene. The immobilization of this macrocycle onto glassy carbon electrodes via diazonium salt chemistry and the electrochemical characterization of the grafted organic layer are also reported.