Recent advances and perspectives for intercalation layered compounds. Part 2: applications in the field of catalysis, environment and health

Intercalation compounds represent a unique class of materials that can be anisotropic (1D and 2D-based topology) or isotropic (3D) through their guest/host superlattice repetitive organisation. Intercalation refers to the reversible introduction of guest species with variable natures into a crystalline host lattice. Different host lattice structures have been used for the preparation of intercalation compounds, and many examples are produced by exploiting the flexibility and the ability of 2D-based hosts to accommodate different guest species, ranging from ions to complex molecules. This reaction is then carried out to allow systematic control and fine tuning of the final properties of the derived compounds, thus allowing them to be used for various applications. This review mainly focuses on the recent applications of intercalation layered compounds (ILCs) based on layered clays, zirconium phosphates, layered double hydroxides and graphene as heterogeneous catalysts, for environmental and health purposes, aiming at collecting and discussing how intercalation processes can be exploited for the selected applications

Recent advances and perspectives on intercalation layered compounds part 1: design and applications in the field of energy

Herein, initially, we present a general overview of the global financial support for chemistry devoted to materials science, specifically intercalation layered compounds (ILCs). Subsequently, the strategies to synthesise these host structures and the corresponding guest–host hybrid assemblies are exemplified on the basis of some families of materials, including pillared clays (PILCs), porous clay heterostructures (PCHs), zirconium phosphate (ZrP), layered double hydroxides (LDHs), graphite intercalation compounds (GICs), graphene-based materials, and MXenes. Additionally, a non-exhaustive survey on their possible application in the field of energy through electrochemical storage, mostly as electrode materials but also as electrolyte additives, is presented, including lithium technologies based on lithium ion batteries (LIBs), and beyond LiBs with a focus on possible alternatives such XIBs (X = Na (NIB), K (KIB), Al (AIB), Zn (ZIB), and Cl (CIB)), reversible Mg batteries (RMBs), dual-ion batteries (DIBs), Zn-air and Zn-sulphur batteries and supercapacitors as well as their relevance in other fields related to (opto)electronics. This selective panorama should help readers better understand the reason why ILCs are expected to meet the challenge of tomorrow as electrode materials

Contribution à l'étude de l'intercalation de chlorures de lanthanoïdes dans le graphite par voie hétérocomplexe

Graphite Intercalation Compounds are useful for low dimensionality studies. Research developed here relates to the development and the physicochemical characterization of GICs with lanthanide chlorides (LnCl3-GICs), the latter constituting one of the last great classes hardly known of GICs. This work results from a bibliographical review leading to the choice of chlorides SmCl3, GdCl3, TbCl3, DyCl3, HoCl3. The development of a hetero-complex way of synthesis made it possible to optimize the conditions of synthesis of LnCl3-GICs of 2nd stage. These compounds are binaries or ternaries which can present structural correlations between free and intercalated chlorides. The magnetic behaviour of lanthanide chlorides and GICs associated was studied. In the free state, chlorides remain mainly paramagnetic between 2 and 300K. In the intercalated state, analyses reveal an attenuation of magnetic interactions.Les composés d'intercalation du graphite sont des matériaux précieux pour l'étude de la basse dimensionnalité. Les recherches développées ici concernent l'élaboration et la caractérisation physico-chimique des composés d'insertion du graphite avec les chlorures de lanthanoïdes (CIGs-LnCl3), ces derniers constituant l'une des dernières grandes classes mal connue de CIGs. Ce travail résulte d'une revue bibliographique conduisant au choix des chlorures de SmCl3, GdCl3, TbCl3, DyCl3, HoCl3. La mise au point d'un protocole de synthèse par voie hétérocomplexe a permis d'optimiser les conditions de synthèse de CIGs de 2ème stade binaires ou ternaires pouvant présenter des corrélations structurales entre chlorures libres et insérés. Le comportement magnétique des chlorures de lanthanoïdes et des CIGs associés a été étudié. A l'état libre, les chlorures restent pour la plupart paramagnétiques entre 2 et 300K. A l'état inséré, les analyses révèlent une atténuation des interactions magnétiques

Quelques problèmes de factorisation dans les anneaux de polynômes

On étudie la non-unicité des factorisations dans des anneaux de polynômes. On s'intéresse tout d'abord à l'élasticité des anneaux A+XI[X] où 1 est un idéal de A : lorsque A est factoriel, on la calcule et on montre qu'elle n'est pas réalisée par une factorisation; lorsque A est de Dedekind, on l'encadre au moyen de constantes liées à 1 et au groupe des classes. On considère ensuite les anneaux V+XB[X] ou V est un DVR de corps K et B est la clôture de V dans une extension finie de K ; outre des résultats généraux, on en calcule l'élasticité (affinant un résultat de Gonzalez) on détermine les ensembles de Geroldinger et de Chapman-Smith et on caractérise les cas de stabilité asymptotique. Enfin, on considère un suranneau d'un anneau semi-factoriel et on étudie quelles conditions doit satisfaire l'extension pour que le suranneau soit lui-même semi-factoriel (répondant a des questions de Coykendall); on applique alors cette analyse au cas des anneaux A+XB[X] (améliorant un résultat de Kim).AIX-MARSEILLE3-BU Sc.St Jérô (130552102) / SudocSudocFranceF

Nouvelles données sur les systèmes graphite-lithium-europium et graphite-lithium-calcium

La méthode solide-liquide en milieu alliage fondu à base de lithium a permis ces dernières années la synthèse de plusieurs composés d'intercalation du graphite (CIG) insérés à coeur au sein des systèmes graphite-lithium-alcalino-terreux. Dans le cadre de cette thèse, cette méthode de synthèse a été étendue aux systèmes graphite-lithium-lanthanoïde, avec une difficulté supplémentaire qui est la méconnaissance des diagrammes de phases binaires lithium-lanthanoïde dont les données sont capitales pour déterminer les domaines de température et de composition chimique des alliages susceptibles de conduire à des CIG. L'immersion de plaquettes de pyrographite dans certains alliages lithium-europium judicieusement choisis a mené à un composé binaire EuC6 ainsi qu'à un composé ternaire graphite-lithium-europium de premier stade.La cinétique de formation de EuC6 a été suivie par diffraction des rayons X ex situ afin de comprendre les différentes étapes de la réaction et d'identifier les phases intermédiaires menant au composé final thermodynamiquement stable. Ce mécanisme révèle un processus réactionnel plus coopératif que celui menant au composé CaC6 et a été décrit par une succession d'étapes contribuant à l'insertion à coeur de l'europium.La composition élémentaire du composé ternaire a été déterminée grâce à une analyse par faisceau d'ions qui a permis de doser simultanément les trois éléments lithium, carbone et europium. Le résultat de cette analyse a conduit à la formule chimique Li0,25Eu1,95C6. EuC6 a également été étudié par microsonde nucléaire, le rapport atomique C/Eu de 6 a ainsi notamment pu être confirmé.Des études structurales ont été menées pour les composés binaires et ternaires. D'une part, il a été possible d'effectuer la résolution structurale complète du binaire EuC6, qui cristallise dans une maille hexagonale de groupe d'espace P63/mmc. D'autre part pour le ternaire Li0,25Eu1,95C6, la séquence d'empilement poly-couche selon l'axe c du feuillet inséré a été modélisée, par combinaison des données structurales avec les informations issues de l'analyse par faisceau d'ions.Les composés d'intercalation du graphite sont des solides de basse dimensionnalité qui se prêtent idéalement à l'étude des relations structure-propriétés. Ainsi dans le système graphite-lithium-calcium, le caractère supraconducteur des composés CaC6 et Li3Ca2C6 a été étudié par spectroscopie de spin de muon ([mu]SR). Pour le système graphite-lithium-europium, des mesures magnétiques réalisées préalablement à ce travail ont été poursuivies et complétées par des analyses [mu]SR (pour Li0,25Eu1,95C6 et EuC6) ainsi que par spectrométrie Mössbauer de 151Eu (pour Li0,25Eu1,95C6) à basse température.The molten alloy solid-liquid method containing lithium has recently enabled the synthesis of several bulk graphite intercalation compounds (GICs) in graphite-lithium-alkaline earth metal systems. As part of this thesis, this synthesis method was extended to graphite-lithium-lanthanide systems, with an additional difficulty which is the lack of knowledge of lithium-lanthanide binary phase diagrams whose data are crucial for determining the temperature range and chemical composition of alloys that may lead to GICs.The immersion of pyrographite platelets in some europium-lithium alloys wisely chosen led to a binary EuC6 compound as well as a graphite-lithium-europium first stage ternary compound.Kinetics study of EuC6 compound was followed by ex situ X-ray diffraction in order to understand the different reaction steps and identify intermediate phases leading to the thermodynamically stable final compound. This mechanism revealed a reaction process more "cooperative" than that leading to CaC6 binary compound and was described by a succession of steps that contribute to the bulk insertion of europium.The elementary composition of the ternary compound was determined by ions beam analysis allowing the simultaneous quantification of the three elements lithium, carbon and europium. The refinement of these analyses led to the chemical formula Li0,25Eu1,95C6 for the ternary compound. EuC6 has also been studied by nuclear microprobe analysis, and especially the C/Eu atomic ratio equal to 6 has been confirmed.Structural studies have been undertaken for binary and ternary compounds. On one hand, it was possible to fully resolve the three-dimensional structure of the binary EuC6, which crystallizes in a hexagonal unit cell with P63/mmc space group. On the other hand, the c axis stacking sequence of the poly-layered intercalated sheet of the ternary compound was modeled by combining structural data with information from the ions beam analysis. The graphite intercalation compounds are low-dimensional solids that are ideal for the study of structure-properties relations. Thus in graphite-lithium-calcium system, superconducting character has been studied for CaC6 and Li3Ca2C6 compounds by muons spin spectroscopy ([mu]SR). For the graphite-lithium-europium system, previous magnetic measurements have been continued and supplemented by [mu]SR analysis (for Li0,25Eu1,95C6 and EuC6) and by low temperature 151Eu Mössbauer spectroscopy (for Li0,25Eu1,95C6).NANCY1-Bib. numérique (543959902) / SudocSudocFranceF

Simple production of high-quality graphene foams by pyrolysis of sodium ethoxide

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Toward the control of graphenic foams

International audienceGraphene-based materials are extensively studied, due to their excellent properties and their wide range of possible applications. Attention has recently been paid to three-dimensional-like graphenic structures, such as crumpled graphene sheets and graphenic foams: these kinds of materials can combine the properties of graphene associating high surface area and porosity, what is particularly interesting for energy or catalysis applications. Most of the synthesis methods leading to such structures are based on graphite oxide exfoliation and re-assembly, but in this work we focus on the preparation of graphenic foams by a solvothermal-based process. We performed a solvothermal reaction between ethanol and sodium at 220°C, during 72 h, under 200 bar, followed by a pyrolysis under nitrogen flow. An extended study of the influence of the temperature (800°C–900°C) of pyrolysis evidences an unexpected strong effect of this parameter on the characteristics of the materials. The optimal conditions provide multi-layer graphene (10 layers) foam with a surface area of 2000 m2·g−1. This work is an important step for the understanding of the mechanisms of the thermal treatment. Post-treatments in different experimental conditions are performed in order to modulate the structure and properties of the graphenic foams

Comparative study of ternary graphite-potassium-metal (M=Tl, Hg, Au) intercalation compounds.

International audiencePotassium-thallium, potassium-mercury, and potassium-gold alloys can be intercalated into graphite, leading to the formation of poly-layered ternary compounds. Different ways of synthesis are involved for the preparation of the corresponding Graphite Intercalation Compounds (GICs). The as-prepared bulk GICs are described in a comparative study, regarding their chemical formula, their formation mechanism, and their structural and superconducting properties. Analogies and differences are pointed out

Multi-scale characterization of graphenic materials synthesized by a solvothermal-based process: Influence of the thermal treatment

International audienceOwing to its exceptional properties and a large range of possible applications, graphene gives rise to a great interest. Several major methods, as mechanical cleavage, liquid phase exfoliation of graphite and supported growth, have been developed these last years. However, it remains difficult to yield industrial quantities of graphene-based materials. Besides the research for the improvement of these major ways of synthesis, we focused on a much less common method: solvothermal synthesis. Graphenic powders can be obtained by a solvothermal reaction between ethanol and sodium followed by a thermal treatment step. We performed the solvothermal reaction and pyrolyzed the as-obtained sodium ethoxide with different temperature and time conditions, in order to study the influence of these two parameters on the final carbon-based sample. Various characterization techniques revealed the obtaining of graphenic materials with large aspect ratio, containing multi-layer graphene (MLG) regions. This study shows the strong influence of temperature and time of pyrolysis on purity, crystallinity and thickness of the samples, and goes toward an optimization of the thermal treatment step

Exhaustive inventory of 2D unit cells commensurate with honeycomb graphene structure

International audienceThe graphene plane possesses a high hexagonal symmetry. Currently, it is largely studied as 2D crystal, especially due to its very interesting potential electronic properties. It is also frequently studied in the 3D stackings as graphite. When a layer of a chemical species is dropped off on a graphene layer, it is common to observe a right adaptation between both 2D crystal networks. This commensurability is consistently studied in this paper by means of a mathematical approach. Through this method, it has been possible to take an inventory of all 2D unit cells commensurate with hexagonal graphene cell. Hexagonal, rectangular and oblique cells can be perfectly listed for the different values of the number of carbon atoms included in the cell. Numerous experimental examples are given in the field of graphite intercalation compounds. And very especially the graphite-electron donors lamellar compounds have been used in order to illustrate the method and its results