Patrice Huguet

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Papers by Patrice Huguet

Characterisation of cation exchange membrane in hydro-organic media by electrochemistry and Raman spectroscopy

by Gérald Pourcelly, Patrice Huguet, and Christophe Innocent

Physical Chemistry Chemical Physics, 2001

ABSTRACT The physicochemical characterisation of a CMX membrane in hydro-organic media was undert... more ABSTRACT The physicochemical characterisation of a CMX membrane in hydro-organic media was undertaken. N-Methylformamide (NMF) and five other solvents with various relative permittivities were investigated. The water content, electrical resistance and transport numbers allowed us to compare the mobility of protons and sodium ions through the membrane as a function of the nature and amount of the organic solvent in the equilibrating solution. Moreover, Raman spectroscopy proved to be a powerful tool to investigate the solvent sorption within the membrane material.

The poisoning effect of mercury complexes with an anionic exchange membrane used in an electrodialysis process: a Raman study

New Journal of Chemistry, 1998

ABSTRACT Poisoning of an ion exchange membrane is one of the most important problems encountered ... more ABSTRACT Poisoning of an ion exchange membrane is one of the most important problems encountered in the electrodialysis process. The poisoning of an anion exchange membrane, used in an electrodialysis process to purify and reconcentrate an hydrochloric acid solution containing mercury chloride, has been investigated. Raman spectroscopic analysis of the contaminated material, combined with electrodialysis results, are presented and discussed. The stoichiometry of the poisoning mercury complex and its action as a counter ion inside the membrane are determined. Moreover, a strong interaction between the membrane fixed sites and the mercury complex is pointed out.

Contribution of Raman Spectroscopy to the Comprehension of Limiting Phenomena Occurring with a Vinylpyridinium Anion Exchange Membrane during the Electrolysis of Cr(VI) Solutions

by Gérald Pourcelly, Patrice Huguet, and Christophe Innocent

Journal of Physical Chemistry B, 1999

Limiting phenomena occur during the recovery of chromic acid solutions by electrodialysis using a... more Limiting phenomena occur during the recovery of chromic acid solutions by electrodialysis using a poly(4vinylpyridinium) anion exchange membrane (AEM). An increase of the cell electrical resistance appears as the current is applied. As for other AEMs, the inner acid concentration is very high compared to that of the equilibrating solution. Raman spectroscopy shows the presence of polychromate ions. Moreover, a competition takes place between the dichromate ions and the poly(4-vinylpyridinium) exchange sites toward protons. The deprotonation of the sites and the very low mobility of the polychromate counterions explain the increase of the electrical resistance.

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Electrochemical and Raman Spectroscopy Study of a Nafion Perfluorosulfonic Membrane in Organic Solvent−Water Mixtures

by Gérald Pourcelly, Patrice Huguet, and Christophe Innocent

Journal of Physical Chemistry B, 2001

... Related Content. Building Energy Storage Device on a Single Nanowire Nano Letters: Building E... more

Microfluidic setup for the visualization of water and methanol content of fuel cell membranes under flow conditions

by Stefano Deabate and Patrice Huguet

Effect of pulsed electric field on electrodialysis of a NaCl solution in sub-limiting current regime

by Gérald Pourcelly, Patrice Huguet, and V. Nikonenko

Electrochimica Acta, 2015

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Effect of coating and plasma treatments on the induced coupled plasma-reactive ionic etching of boron-doped diamond for microelectromechanical systems (MEMS) applications

Nanoscience Methods, 2014

ABSTRACT Induced coupled plasma etching was performed on poly-crystalline boron-doped diamond (BD... more ABSTRACT Induced coupled plasma etching was performed on poly-crystalline boron-doped diamond (BDD) films synthesized by microwave assisted chemical vapor deposition (MWCVD). Effects of the input power and of the gas composition and pressure on etching performances have been investigated. A basic aluminium layer and a new hybrid material have been studied as protecting film for the patterning. Best conditions to get high etch rates were a gas ratio Ar/O2 of 27% (vol.) under 10 mTorr at 200 W (input power). Aluminium (Al) masking induced un-intentional whiskers formation which was removable using CHF3 as a reactive gas with the drawback to lower the process selectivity. In order to get both a high etching rate and a high selectivity, a hybrid material based on an organic/mineral resin was then used as the masking material. This performing photoresist film allowed etching a 3.6-μm-thick BDD film at 200 nm min−1.

In situ dynamic characterization of water transport and proton mobility in Nafion by ATR-FTIR and micro Raman spectroscopy

by Patrice Huguet and Stefano Deabate

Raman Microspectroscopy as a Useful Tool for In Situ and Operando Studies of Water Transport in Perfluorosulfonic Membranes for PEMFCs

by Patrice Huguet and Stefano Deabate

Fuel Cells, 2014

ABSTRACT An operating PEMFC for commercial use must be able to adapt to variations in power deman... more ABSTRACT An operating PEMFC for commercial use must be able to adapt to variations in power demands and operating conditions while maintaining near optimal performance. Current research shows that one of the main issues affecting power output, stability, and longevity is the quantity and distribution of water in the system. The last are strongly affected by the sorption and transport properties of the polymer electrolyte. Thus, the need for a fundamental understanding of water transport in the PEMFC membrane-electrode assembly has motivated, over the past few years, the development of new operando diagnostic tools sensitive to the membrane hydration. Among these, the most recent technique is based on confocal Raman microspectroscopy. This tutorial review is devoted to the illustration of the basis of this method, with a particular focus on the Raman signal processing needed to obtain reliable through-plane water concentration profiles across PFSA membranes. Then, the potential of in situ and operando μ-Raman is highlighted by reviewing the few studies reported to date, completed by the most recent results obtained by our group. Finally, advantages and drawbacks of operando Raman microspectroscopy are shortly discussed.

Asymmetric bi-layer PFSA membranes as model systems for the study of water management in the PEMFC

by Patrice Huguet and Stefano Deabate

Phys. Chem. Chem. Phys., 2014

New bi-layer PFSA membranes made of Nafion® NRE212 and Aquivion™ E79-05s with different equivalen... more New bi-layer PFSA membranes made of Nafion® NRE212 and Aquivion™ E79-05s with different equivalent weights are prepared with the aim of managing water repartition in the PEMFC. The membrane water transport properties, i.e. back-diffusion and electroosmosis, as well as the electrochemical performances, are compared to those of state-of-art materials. The actual water content (the inner water concentration profile across the membrane thickness) is measured under operation in the fuel cell by in situ Raman microspectroscopy. The orientation of the equivalent weight gradient with respect to the water external gradient and to the proton flow direction affects the membrane water content, the water transport ability and, thus, the fuel cell performances. Higher power outputs, related to lower ohmic losses, are observed when the membrane is assembled with the lower equivalent weight layer (Aquivion™) at the anode side. This orientation, corresponding to enhanced water transport by back-flow while electroosmosis remains unaffected, results in the higher hydration of the membrane and of the anode active layer during operation. Also, polarization data suggest a different water repartition in the fuel cell along the on-plane direction. Even if the interest in multi-layer PFSA membranes as perspective electrolytes for PEMFCs is not definitively attested, these materials appear to be excellent model systems to establish relationships between the membrane transport properties, the water distribution in the fuel cell and the electrochemical performances. Thanks to the micrometric resolution, in situ Raman microspectroscopy proves to be a unique tool to measure the actual hydration of the membrane at the surface swept by the hydrated feed gases during operation, so that it can be used as a local probe of the water concentration evolution along the gas distribution channels according to changing working conditions.

Influence of Compressive Stress on the Water Content of Perfluorosulphonated Membranes: A μ-Raman Study

by Patrice Huguet and Stefano Deabate

Fuel Cells, 2011

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Confocal Raman Microscopy for Membrane Content Visualization

by Patrice Huguet and Stefano Deabate

Monitoring and Visualizing Membrane-Based Processes, 2009

The crossed interdiffusion of sodium nitrate and sulfate through an anion exchange membrane, as studied by Raman spectroscopy

by V. Nikonenko and Patrice Huguet

New Journal of Chemistry, 2005

ABSTRACT Raman spectroscopy is applied to visualize concentration profiles in solution adjacent t... more ABSTRACT Raman spectroscopy is applied to visualize concentration profiles in solution adjacent to the top of DSV anion exchange membranes in horizontal positions. The concentration profiles of sulfates, nitrates and their fluxes through the membrane are recorded as a function of time during 13–15 h experiments. A three layer mathematical model based on extended Nernst–Planck equations with a convective term is developed. The membrane’s kinetic and static parameters, such as ionic diffusion and ion exchange coefficients, are determined by separate experiments. Only one parameter, the diffusion boundary layer thickness, δ, is fitted. It is found that the model described fluxes well, especially when the variation of δ is taken into account. At the same time, the model gives nearly linear concentration profiles, whereas the measured profiles are much more complicated. This complicated shape is explained by natural convection and the emergence of the Bènard vortexes in the system.

In-Situ Measurement of Electroosmotic Drag Coefficient in Nafion Membrane for the PEMFC

The Journal of Physical Chemistry B, 2011

A new method based on hydrogen pump has been developed to measure the electroosmotic drag coeffic... more A new method based on hydrogen pump has been developed to measure the electroosmotic drag coefficient in representative PEMFC operating conditions. It allows eliminating the back-flow of water which leads to some errors in the calculation of this coefficient with previously reported electrochemical methods. Measurements have been performed on 50 μm thick Nafion membranes both extruded and recast. Contrary to what has been described in most of previous published works, the electroosmotic drag coefficient decreases as the membrane water content increases. The same trend is observed for temperatures between 25 and 80 °C. For the same membrane water content, the electroosmotic drag coefficient increases with temperature. In the same condition, there is no difference in drag coefficient for extruded Nafion N112 and recast Nafion NRE212. These results are discussed on the basis of the two commonly accepted proton transport mechanisms, namely, Grotthus and vehicular.

Probing proton dissociation in ionic polymers by means of in situ ATR-FTIR spectroscopy

by Patrice Huguet and Stefano Deabate

Physical Chemistry Chemical Physics, 2008

The hydration process of cationic membrane protogenic groups was investigated using in situ ATR-F... more The hydration process of cationic membrane protogenic groups was investigated using in situ ATR-FTIR spectroscopy. The aim of this study is to provide a relationship between the hydration degree of the membrane and the dissociation state of exchange sites inside the polymer material. IR spectra were recorded by means of an environmental device specifically manufactured to allow the control of water vapour pressure in equilibrium with the sample. The behaviour of Nafion 112 and sulfonated poly(ether ether ketone) (S-PEEK), in both proton and sodium forms, was compared. IR data, analyzed and fitted in the 800-1850 cm(-1) spectral range, gave precise information on the assignment of sulfonic group vibrational modes. The results of this study improve the understanding of the transition phenomena between dissociated and undissociated states of the grafted sites in protonic conductors.

Depth-resolved micro-Raman spectroscopy of tri-layer PFSA membrane for PEM fuel cells: how to obtain reliable inner water contents

by Patrice Huguet and Stefano Deabate

Journal of Raman Spectroscopy, 2013

ABSTRACT Raman depth‐profiling microspectroscopy is currently emerging as a fast and non‐invasive... more ABSTRACT Raman depth‐profiling microspectroscopy is currently emerging as a fast and non‐invasive method for the local content measurement of water diffusing across the perfluorosulfonic acid polymer used as electrolyte in low‐temperature fuel cells. However, water depth profiles obtained thereby are affected by the gradual degradation of the Raman signal as the exciting radiation is focused deeper into the sample and, thus, usually exhibit artificial gradients. The appropriate way to rectify raw data, in order to measure reliable inner water contents, is discussed in the case of perfluorosulfonic acid membranes soaked in water. The method is tested on a tri‐layer material composed by stacked ionomers with different chemical composition, ionic exchange capacity and swelling. Comparison of Raman spectra of the different ionomers, obtained under strictly the same hydration and optical conditions, allows critical discussion of previously reported band assignments. It is shown that Raman bands arising from the polymer backbone and from the side chain can be readily discriminated. Reliable water concentration profiles can then be obtained from the ratio between the Raman signal of sorbed water and of the polymer phase. Comparison with depth profiles obtained by using the pure water signal as internal reference shows that quantitative measurement requires the careful choice of the adequate Raman bands for representing the ionomer occupation of the volume probed by the exciting radiation. Different to what usually performed, the ionomer Raman signal to be integrated for compensating optical losses should include both bands arising from the polymer backbone and side chains. Last, obtaining accurate water concentration profiles also needs the knowledge of the so‐called optical factor β, i.e. the ratio between the scattering cross sections of ionomer chemical groups and sorbed water, which has to be measured by independent Raman experiments. Copyright © 2012 John Wiley &amp; Sons, Ltd.

In situ confocal-Raman measurement of water and methanol concentration profiles in Nafion® membrane under cross-transport conditions

by Patrice Huguet and Stefano Deabate

Journal of Power Sources, 2008

The local concentration gradients of water and methanol within a Nafion ® membrane are measured w... more The local concentration gradients of water and methanol within a Nafion ® membrane are measured with a new microfluidic cell specially designed for depth measurement by confocal micro-Raman spectroscopy. The experimental concentration profiles of solvents, obtained in situ under cross-transport conditions, are fitted taking into account the contribution of the experimental set-up to the Raman response. This method allows to measure the concentration ratios of methanol and water at the solution-membrane interface as well as the real concentration gradients of these solvents within the membrane medium. These parameters are critical for a better understanding of membrane transport properties and cannot be directly measured by other techniques. Indeed, results here reported show that internal gradients differ from those that can be estimated from methods measuring external concentrations.

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Protonation and diffusion phenomena in poly(4-vinylpyridine)-based weak anion-exchange membranes

Journal of Membrane Science, 2009

Purification and concentration of mineral acids can be carried through dialysis processes with an... more Purification and concentration of mineral acids can be carried through dialysis processes with anionexchange membranes. Weak anion-exchange membranes are active only for sufficient acid concentrations in their structure, however too high concentrations result in significant proton leakage, i.e. reduction in the transport selectivity. The present paper deals with the kinetics of acid diffusion through two commercial poly(4-vinylpyridine)-based weak anion-exchange membranes which comprises protonation of the exchanging groups. The electrical conductivity and the water content of the membranes were shown to be linear function of the protonation degree of poly(4-vinylpyridine) groups. Kinetics of protonation and diffusion of acids have been investigated using dialysis cells. First diffusion kinetics has been studied in a conventional dialysis cell, by observation of the transient acid transport through the membrane (macroscopic studies). Besides, protonation kinetics was investigated using a miniaturised dialysis cell coupled to confocal Raman microspectrometer. Profiles of non-protonated and protonated sites in the membrane were recorded along time, depending on the membrane grade and the nature of the acid transported. Interpretation of the two sources of data yielded permeability coefficient and diffusion coefficient, whose meaning is discussed. A mechanism for protonation/diffusion in this type of weak anion exchangers in acidic media was proposed.

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Swelling and permeability of Nafion®117 in water–methanol solutions: An experimental and modelling investigation

by V. Nikonenko and Patrice Huguet

Journal of Membrane Science, 2011

The swelling and diffusion behaviour of a Nafion ® 117 ion-exchange membrane was investigated in ... more The swelling and diffusion behaviour of a Nafion ® 117 ion-exchange membrane was investigated in mixed water-methanol solutions. The membrane porosity was found as a function of the methanol content in solution. The water and methanol uptake was determined by Raman spectrometry. The permeation experiments were realized in conditions where a membrane initially separated a water-methanol electrolyte solution from a solution prepared with pure water, both solutions containing either 0.1 M HCl or 0.5 M HCl. Different rotation speeds of stirrer rods were applied in the range of 70-700 rpm. A mathematical model for water-methanol permeation through a membrane taking into account the transfer through adjacent diffusion boundary layers (DBLs) and the dependence of the methanol diffusion coefficient on the methanol concentration was developed. The DBL thickness, ı, and the methanol permeability, P*, were determined by numerical fitting of experimental data. It was found that the rotating stirrers used in the cell were almost as efficient as rotating electrodes or membranes: we have found that ı ≈ 1.2ı Levich , where ␦ Levich was calculated by the well-known Levich equation for rotating disc electrodes. However, the contribution of diffusion resistance of DBL into the overall resistance of the three-layer system was not negligible, even at high rotation speeds, due to high methanol permeation through Nafion ® 117. When taking into account the DBLs, the "true" methanol permeability of Nafion ® 117 in the presence of 0.5 M HCl in the upstream and downstream compartments (at 25 • C) was equal to 0.44 × 10 −5 cm 2 s −1 . If the contribution of DBLs was not considered, the apparent methanol permeability at rotation speed of 70 rpm (ı ≈ 76 m) was equal to 0.35 × 10 −5 cm 2 s −1 . Even at 650 rpm (ı ≈ 25 m), the apparent methanol permeability, (0.41 × 10 −5 cm 2 s −1 ) was still lower than its "true" value. An approximate equation relating the apparent (efficient) non-electrolyte permeability with the "true" membrane permeability and the diffusion layer thickness was deduced following the approach proposed by Helfferich. (L. Dammak). losses in cell potential . At low current densities, chemical water-methanol diffusion is the main mechanism of the solvent transport, while at high current densities, the "cross-over" is essentially controlled by electro-osmotic water drag .

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Application of relaxation periods during electrodialysis of a casein solution: Impact on anion-exchange membrane fouling

Journal of Membrane Science, 2007

Electrodialysis (ED) is a membrane process used on a large scale. However, one of the common prob... more Electrodialysis (ED) is a membrane process used on a large scale. However, one of the common problems is fouling of ion-exchange membranes stacked in the cell. The use of pulsed power, consisting in applying a constant current density during a fixed time of application (T on ) followed by a pause duration (T off ), was demonstrated recently as an effective fouling mitigation method for electrodialysis. Up until now, no work has investigated the potential of electrodialysis using pulsed electric field on protein fouling. The aim of the present work was to study the influence of pulsed electric field (PEF) with a low frequency square shaped periodic signal (T on = 10 s-T off = 10 s, T on = 10 s-T off = 40 s) in comparison with dc current during electrodialysis of a casein solution at different current densities (10, 20 and 30 mA/cm 2 ) on membrane fouling. It appeared from these results that PEF, under certain conditions of pulse, would avoid fouling on anion-exchange membranes. For 10 s-40 s pulsed electric field conditions, no fouling was observed with any density, while for 10 s-10 s PEF conditions, fouling appeared only at current density over 10 mA/cm 2 . dc current, whatever the current density conditions, led to a fouling on the diluate side of the AEM. Furthermore, when fouling occurred, magnitude layer thickness and dry weight increased with the applied current density. The nature of the fouling was identified as 97% protein. The protein fouling would be due to the dissociation of water molecules and/or heat increase at the anion-exchange membrane interface. The relaxation time of the pulse would limit both phenomena on the membrane.

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