3D hierarchical and porous layered double hydroxide structures: an overview of synthesis methods and applications

International audienceNanostructured layered double hydroxide (LDH) materials with unique diffusion properties, large surface area along with desired functionalities have recently been produced for a number of well-established and advanced fields of applications. In this review, we describe and discuss the main synthetic methods that have been reported for the fabrication of porous LDH with tailored chemical composition and porosity. The efficiency of soft and hard templating approaches is particularly reviewed. A special emphasis is put on the microstructure and porosity of the materials according to the synthetic method involved. Finally, the performance enhancement of the materials due to the presence of porosity, especially macroporosity, in applications such as pollutant removal, catalysis and energy storage and conversion is overviewed

Advances in Layered double Hydroxide-based Materials for CO2 Electroreduction: A Comprehensive Review of recent Research Progress

International audiencePlease provide Text for Abstract. Over the past decade, layered double hydroxides (LDH), known as ionic lamellarcompounds, have been described as promising materials for CO2 adsorption and its photocatalytic conversion. These LDHapplications have been already reviewed in previous papers. Interestingly, over the past three years, LDH have been alsoused for the design of modified electrodes applied to CO2 electroreduction (CO2ER). This review presents, for the firsttime, an overview of these recent developments in the synthesis of electrocatalysts based on LDH and their performance inCO2ER. In this field of applications, LDH act either i) as electrocatalysts, ii) as supports for other electrocatalysts, iii) asprecursors for the generation of metal nanoparticles or metal oxide electrocatalysts through chemical or electrochemicalconversions. The composition of the as-prepared electrocatalysts and electrolysis conditions modify the reduction productsformed. ZnAl-based LDH appears to be a promising catalyst for CO formation, and CuAl-LDH for formate. A chemical orelectrochemical activation of copper-based LDH to obtain Cu+ and/or Cu0 active species appears to be a very promisingmethod for generating valuable products, such as acetate, methanol or ethylene. This review will be useful for newprospects on LDH-based electrocatalysts applied on CO2ER

Pickering emulsions based on layered double hydroxides and metal hydroxides

International audienceAs previously underlined in this book, Pickering emulsions have in recent years gained increasing attention due to their interesting properties related to the replacement of surfactants by solid microparticles or nanoparticles. Such change in the nature of the stabilizer confers higher stability and lower toxicity to the emulsions. This chapter focus on the recent advances in the specific use of a peculiar class of inorganic bidimensionnal particles the Layered Double Hydroxides (LDH) and hydroxides salts in Pickering emulsion process. The properties of the two main classes of LDH involved in the stabilization of emulsion that is pristine materials and modified LDH with organic anions, are described. Then the different results obtained for oil-in-water, water-in-oil and water-in-water involving LDH or hydroxides salt particles are discussed. At last, the interest of Pickering emulsion stabilized by LDH in various applications are also reviewed

A Review of Vanadium Dioxide as an Actor of Nanothermochromism: Challenges and Perspectives for Polymer Nanocomposites

International audienceVO2 has been intensively studied as a model system for metal‐insulator transition (MIT), ever since its phase switching behavior at relatively low temperature (Tc = 68 °C) was discovered. Its thermo‐active characteristics have been studied for applications in thermal solar collectors to prevent overheating of the fluid absorber, smart windows, and smart tiles to optimize thermal comfort in buildings. In the last few decades, strong efforts were made to develop protocols to process VO2‐based material into thin films, coatings, porous layers, and glazings in order to provide thermo‐active properties to common substrates. A selection of complementary works in both the synthesis of VO2 nanoparticles and formulation of VO2‐polymer nanocomposites is proposed in the present review. The perspective of this work is to provide an easy entry to the thermochromic nanocomposite research field as a tutorial to tackle future challenges such as improving the application‐oriented properties, in particular transition temperature Tc and solar transmittance modulation ΔTsol. Synthesis techniques to fabricate VO2 particles and nanoparticles and strategies to insert VO2 particles in a polymer matrix are presented

Layered double hydroxides: where should research stress on for massive scaling up?

International audienceFor more than half a century, layered double hydroxides (LDHs) have attracted great attention from the scientific community. These materials belong to a rare anionic clay group and have demonstrated amazing physicochemical properties, leading to disruptive, cost-effective and eco-friendly applications for health, environment and agriculture. However, LDHs are not widely used in daily items, nor are they massively applied in industry despite their very good potential for large-scale development. This study looks at the current shortcomings preventing the industrial implementation of LDH powders while evidencing and discussing the strategies to encourage research to bridge the gaps on this topic

Intracrystalline alkylation of benzoate ions into layered double hydroxides

Several layered double hydroxides (LDHs) containing metals of different nature intercalated with benzoate anions have been synthesised in order to study the O-alkylation reaction of the interlayered species with alkyl halide in dry media conditions. In all the cases, the expected ester was obtained with good yield (>60%). The presence of anionic benzoate in the structure was prefered to obtain high selectivity and yield, in comparison with the use of sodium benzoate supported as a salt. The use of MW irradiation to promote these reactions has permitted the reaction time to be reduced considerably. The influence of water present in the LDH on the ester formation has also been investigated. Characterisation of the LDH support before and after reaction is also presented, showing the influence of the nature of the cations located in the octahedral sheets. The support can be regenerated, with no effect on the reactivity.This work was partially supported by the CICYT (Spain). V. Prevot thanks the Conseil Regional of Auvergne (France) for a postdoctoral fellowship. The authors gratefully acknowledge technical assistance from J. Merino and M. A. Muro (ICMM) and from V. Ravel and A. M. Mafille, from Techinauv, who recorded the SEM micrographs. We also thank A. L. Garcia-Ponce for helpful discussions

Effect of Pseudomonas sp. ADP-anionic clay interactions on atrazine biodegradation

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Intracrystalline reactivity of layered double hydroxides: Carboxylate alkylations in dry media

This work concerns the reactivity in dry media conditions, i.e. without solvents, of layered double hydroxide (LDH) solids, containing carboxylate ions in their structure, towards alkyl and benzyl halides. Reaction occurs giving the corresponding esters, with excellent yield and selectivity, and preserving the lamellar arrangement of the pristine solids. The reactions were activated by conventional thermal treatment (100 °C) or by microwave (MW) irradiation.This work was partially supported by the CICYT, Spain. The authors gratefully acknowledge technical assistance from J. Merino and M. A. Muro. We also thank M. A. Martin Luengo and P. Aranda for helpful discussions and M. Yates for revising the manuscript

Contribution des argiles ferrifères à l'élaboration de biocapteurs ampérométriques : Etude de l'interaction de l'Hémoglobine avec des Argiles et des Hydroxydes Doubles Lamellaires.

In this thesis work, we were interested in the development of electrochemical biosensors by using iron rich clays and Layered Doubles Hydroxides (LDH), as matrices for immobilizing hemoglobin (Hb). The aim of this work was to study the contribution of iron structural materials in improving the performance of biosensors by a phenomenon of redox catalysis. Hemoglobin is a metalloprotein containing iron porphyrin (heme) as prosthetic group. A preferred orientation of the biomolecule on an electrode surface may improve the direct electron transfer between the active site of the protein and the electrode. The electro-catalytic properties of immobilized Hb were studied for the reduction of hydrogen peroxide (H2O2) and, allowed the development of different amperometric biosensors. We have immobilized Hb in iron rich cationic clays (nontronite from Garfield, montmorillonites) and in a montmorillonite containing non iron as a reference. The electrochemical properties of these clays were studied by cyclic voltammetry and impedancemetry. The adsorption isotherms of Hb on these clays showed a strong affinity of Hb for nontronite. We have also shown that octahedral structural iron clays, especially nontronite, improve the direct electron transfer between Hb and electrode. Immobilization of Hb in LDH of different compositions (MgAl and ZnAl) was performed by adsorption and coprecipitation methods. We noted that iron situated in octahedral site in LDH (MgFe) is not electroactive and therefore can not improve the electro-enzymatic process. The chemical and morphological characterizations of the Hb-LDH biohybrids were carried out by several techniques, such as XRD, IR, UV, SEM and TEM. We noted a partial denaturation of the tertiary structure of the protein, due to the formation hydrogen bonds between the biomolecule and hydroxyl layers of LDH, which limits the accessibility of heme to direct electronic transfer. Besides the interactions of Hb with LDH, we was also interested in the immobilization of a negatively charged metalloporphyrin, (FeTSPP) in three different LDH: Zn2Al Mg2Al and Zn2Cr and we have starting the first electrochemical study of these materials.Ce travail de thèse est consacré au développement de biocapteurs électrochimiques en utilisant des argiles ou des hydroxydes doubles lamellaires (HDL), riches en fer, comme matrices d'immobilisation de l'hémoglobine (Hb). Le but était de mettre en évidence la contribution des propriétés redox de ces matériaux dans l'amélioration des performances des biocapteurs par un phénomène de catalyse redox. L'hémoglobine est une métalloprotéine qui contient des porphyrines au fer (hème) comme sous-unité prosthétique. Une orientation privilégiée de cette biomolécule à la surface d'une électrode permet le transfert direct d'électrons entre le site actif de la protéine et l'électrode. Les propriétés électro-catalytiques de l'Hb immobilisée ont été étudiées pour la réduction du peroxyde d'hydrogène et ont permis la réalisation de différents biocapteurs ampérométriques. Nous avons immobilisé l'Hb dans plusieurs argiles cationiques contenant du fer : la nontronite de Garfield, des montmorillonites ferrifères synthétiques ou naturelles, ainsi qu'une montmorillonite synthétique servant de référence. Les propriétés électrochimiques de ces argiles ont été évaluées en voltammétrie cyclique et en impédancemétrie, en relation avec leurs propriétés structurales. Les isothermes d'adsorption de l'Hb dans ces argiles ont été établis montrant une forte affinité de l'Hb pour la nontronite. Nous avons montré que les argiles riches en fer octaédrique, notamment la nontronite, améliorent le transfert direct d'électrons entre l'Hb et l'électrode. L'immobilisation de l'Hb dans des HDL, de compositions différentes (MgAl et ZnAl) a été réalisée par adsorption et coprécipitation. Il faut noter que le fer situé en site octaédrique dans les HDL (MgFe) n'est pas électroactif et ne peut donc pas intervenir dans le processus électro-enzymatique. Les caractérisations physico-chimiques et morphologiques des biohybrides Hb-HDL ont été faites par plusieurs techniques, comme la DRX, IR, UV, MEB et MET, montrant une dénaturation partielle de la structure tertiaire de la protéine par la formation de liaisons hydrogènes entre la biomolécule et les feuillets hydroxylés des HDL; ce qui limite l'accessibilité de l'hème au transfert électronique direct. Outre l'immobilisation de l'Hb dans les HDL, nous avons également intercalé une métalloporphyrine chargée négativement, la FeTSPP, dans trois HDL de compositions différentes : Zn2Al, Mg2Al et Zn2Cr et nous avons réalisé la première étude électrochimique avec ces matériaux

Tailoring Hybrid Layered Double Hydroxides for the Development of Innovative Applications

International audienceHybrid materials based on layered double hydroxides (LDHs) exhibit great potential in diverse fields such as health care, polymer composites, environment, catalysis, and energy generation. Indeed, the compositional flexibility and the scalability of LDH structures, their low cost, and their ease of synthesis have made hybrid LDHs extremely attractive for constructing smart and high-performance multifunctional materials. This review provides a comprehensive and critical overview of the current research on multifunctional hybrid LDHs. Organic–inorganic hybrid LDHs, intercalated and surface-immobilized structures, are both specifically addressed. The new trends and strategies for hybrid LDH synthesis are first described, and then the potential of the latest hybrid LDHs, polymer LDH nanocomposites, and LDH bio-nanocomposites are presented. Significant achievements published from ≈2010, including authors' results, which employ hybrid LDH assemblies in materials science, medicine, polymer nanocomposites, cement chemistry, and environmental technologies, are specifically addressed. It is concluded with remarks on present challenges and future prospects