Through a topochemical oxidative reaction (TOR) under air, a β‐Co(OH)2 brucite type structure is converted into a monometallic CoIICoIII–CO3 layered double hydroxide (LDH). The structural and ...morphological characterizations are performed using powder X‐ray diffraction, Fourier‐transformed IR spectroscopy, and scanning and transmission electron microscopy. The local structure is scrutinized using an extended X‐ray absorption fine structure, X‐ray absorption near‐edge structure, and pair distribution function analysis. The chemical composition of pristine material and its derivatives (electrochemically treated) are identified by thermogravimetry analysis for the bulk and X‐ray photoelectron spectroscopy for the surface. The electrochemical behavior is investigated on deposited thin films in aqueous electrolyte (KOH) by cyclic voltammetry and electrochemical impedance spectroscopy, and their capacitive properties are further investigated by Galvanostatic cycling with potential limitation. The charge capacity is found to be as high as 1490 F g−1 for CoIICoIII–CO3 LDH at a current density of 0.5 A g−1. The performances of these materials are described using Ragone plots, which finally allow us to propose them as promising supercapacitor materials. A surface‐to‐bulk comparison using the above characterization techniques gives insight into the cyclability and reversibility limits of this material.
Through a topochemical oxidative reaction (TOR) of β‐Co(OH)2, cobalt mono‐metal layered double hydroxide CoII–CoIII is obtained and analyzed using a combined set of characterization techniques. The results agree with chemical titration of the oxidation state of Co atoms. Remarkable capacitances are obtained, close to 1500 F g−1 at 0.5 A g−1, into KOH aqueous electrolyte.
A sol-gel synthesis using modified poly(methyl methacrylate) (PMMA) bearing trimethoxysilane groups and tetraethoxysilane (TEOS) allowed immobilization of very high loadings of ionic liquid BMImNTf ...sub(2) within nanocomposite PMMA-silica membranes. The ionic liquid (IL) provided both flexibility and ionic conductivity, while the silica nanofiller covalently bonded to the polymer chains maintained mechanical strength, as shown by a DMA and tensile test. Complex impedance spectroscopy evidenced a critical threshold in ionic conductivity around 76%, which was ascribed to an unusual transition from "polymer-in-salt" to "quasi-liquid" electrolyte behaviour. Outstanding IL loadings as high as 90 wt% were reached, resulting in the same ionic conductivity as the pure IL.
Conversion cathodes such as metal fluorides are particularly interesting for their theoretical capacities up to 711 mAh/g when used in Li-ion batteries. However, they generally suffer from high ...hysteresis and/or poor cyclability. To overcome these problems, ternary metal fluorides are being explored to improve electrochemical properties compared to the usual binary fluorides: a polymer electrolyte membrane is also used to avoid undesirable cathode-electrolyte reactions and to assess the compatibility of such cathode materials with All Solid State Batteries (ASSB). Among the multi-metallic models, copper hexacyanoferrate Cu3Fe(CN)62.nH2O from the Prussian blue analogue family (PBA), is fluorinated under pure fluorine gas at selected temperatures according to preliminary thermogravimetric mass spectrometry analyses. Using X-ray absorption spectroscopy and diffraction, an inverse perovskite structure Cu(H2O)43·(FeF6)2 is identified at a fluorination temperature of 140 °C and an intimate mixture of CuF2 and FeF3 is formed at 350 °C. The cyclic voltammogram of the latter compared to that of a ball-milled sample of similar composition CuF2/FeF3 highlights the advantages of MMTF multi-metallic template fluorination for electrochemical properties, interpreted by the high level of homogeneous dispersion of the redox centers obtained with this method compared to the mechanical milling reference evaluated by SEM. The fluorides are also found to be compatible with the commercial solid polymer electrolyte membrane PEO-LiTFSI (Poly Ethylene Oxide impregnated with Lithium bis(trifluoromethanesulfonyl)imide), underlining the suitability of the MMTF-prepared cathodes for use in the ASSB.
Evolution of the local environment of copper (light green) and iron atoms (orange) according to ICSD reference structures of phases identified by XRD assignments (Oxygen: red ; Nitrogen: blue ; Carbon: gray ; fluorine: green) Display omitted
•New methodology of fluorination of BPA inorganic template (MMTF).•Anti-perovskite phase Cu(H2O)43·(FeF6)2 obtained at low fluorination temperature, confirmed by XAS and XRD.•An intimate structure of CuF2 and FeF3 at high fluorination temperature.•New compounds useable as cathode in polymer lithium ion battery.
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•1–10 layers intercalated antioxidants finely fabricated in a simple route.•Well-dispersed ultrathin intercalated antioxidants were obtained in PP matrix.•Relationship between ...thickness and antioxidative performance is disclosed.•Island effect of ultrathin antioxidants stimulated thermal stability of composites.
A series of different layers ultrathin antioxidant intercalated layered double hydroxides (nL-LDHs, n = 1 to 10) were fabricated in a simple separate nucleation and aging steps route, and the anti-aging performance of nL-LDH/polypropylene (PP) composites was carefully investigated. With the increase of Mg2+concentration from 0.01 mol/L to 0.3 mol/L, the corresponding thickness of nL-LDHs was varied from 2.58 nm to 26.7 nm related to the layer number from n = 1 to n = 10, and the radical-scavenging activity of nL-LDHs was reduced from 51.5 % to 30.2 %. The ultrathin nL-LDHs antioxidants were well dispersed in PP to produce nL-LDH/PP composites with a mass loading of 0.4 wt% via a solvent mixing method. The nL-LDHs antioxidants as a multifunctional agent influence crystallization behavior of PP, and enhance anti-aging performance of nL-LDHs/PP composites. 3L-LDH exhibited the best anti-aging performance and appreciate anti-migration resistance for nL-LDHs/PP composites, which is better than commercial Irganox 1010.
Iron and copper fluorides are of interest as conversion cathode materials in lithium batteries but they suffer from high hysteresis and low cyclability, respectively. To overcome these limitations ...and take advantage of the electrochemical properties of each of the fluorides, fluoride mixtures that combine the two redox centers Fe3+ and Cu2+ are synthesized using Layered Double Hydroxides (LDH) as a 2D multi-metallic template. Hydrotalcite-type phases substituted with Cu2+ and Fe3+ ions are prepared by coprecipitation then fluorinated with fluorine gas in static mode at temperatures chosen according to their thermal evolution monitored by mass spectrometry. After each fluorination treatment, the materials are characterized by X-ray diffraction and most LDH materials are found stable up to 200 °C, treatment above leads to the formation of fluorides of each of the cations. The initial dispersion of the cations in the LDH sheets nevertheless allows, after fluorination, a composite of fluorides making them totally accessible to the phenomenon of electrochemical conversion shown here in a metallic lithium battery assembly with a Solid Polymer Electrolyte (SPE). In such All-Solid-State Battery (ASSB) configuration often limiting in terms of columbic efficiency, 76% the first discharge capacity is recovered in charge for an optimized composition (up to 560 mAh.g−1). This good reversibility positions these LDH templates very well for future investigations in the field of electrochemical storage.
Hindered phenolic antioxidants have been extensively recognized and applied to boost the heat resistance and oxidative aging performance of poly(propylene) (PP) composites. Low-molecular-weight ...antioxidants are easy to volatilize, migrate, and be extracted from PP or PP-based products, which can directly reduce the antithermal oxidative aging effect of PP and its composites, and it can contaminate food or drugs under its packaging. The design of an efficient and durable antioxidant with antimigration performance has drawn the attention of researchers. Currently, three main approaches are explored: (I) enhancement of molecular weight, that is, high molecular weight of antioxidants can stimulate the structure stability and the resistance toward migration; (II) inorganic immobilization, which involves immobilizing the antioxidants on inorganic substrate to enhance the dispersion and the antimigration performance; and (III) intercalation-mediated assembly, which involved intercalating low-molecular-weight antioxidants into the interlayer region of a layered host to boost antimigration performance based on the host–guest interaction.
This study presents the intercalation into Layered Double Hydroxides (LDHs) of two sulfonated organic molecules featuring the mesoionic triazolium scaffold. These sulfonated fluorophores exhibited ...excellent solubility in aqueous basic solutions, facilitating their compatibility with the synthesis of LDHs through coprecipitation methods. We applied the size-matching interlayer space (SMIS) approach by substituting a portion of a mono- or dianionic surfactant used in LDH preparation by the sulfonated fluorophore, we aimed to match the size of the luminescent interleaved guest effectively. Our investigation focused on two anion spacers: the classic monoanionic dodecyl sulfate (DS) and the dianionic phenylene dipropionate (PPA). Our results indicated that the latter spacer allowed a more efficient insertion of the fluorescent guest. Thermal resistance analysis underscored the robustness of the final hybrid materials, suggesting a promising design strategy for luminescent materials when applied in diverse applications.
Inorganic-organic hybrid materials obtained from mesoionic triazolium fluorophores and layered double hydroxides display highly efficient photoluminescence in the solid state.
This work investigates emulsion templating to synthesize hexadecane oil/geopolymer composites. In a system with hexadecane as the internal (dispersed) phase and an alkali activated continuous phase ...without added surfactant, adding aluminosilicate clay particles does not increase resistance against creaming or coalescence, while adding a surfactant (L35 or CTAB) stabilizes the solid-liquid interface. Infrared studies and rheological studies of the associated geopolymerization determined that the presence of the organic phase or surfactant has no significant effect on the geopolymerization kinetics, as determined by the change in time of the Si-O-T IR stretching frequency and the rheological moduli involved during the process. The stabilization of the organic template is reminiscent of Pickering emulsion even though we employ a much greater amount of inorganic material for geopolymer formation. Although the addition of surfactant has a significant effect on the behavior of the paste, the percolation of the network remains unmodified, highlighting the fact that the phenomenon is not dependent on viscosity. Finally, rheological measurements were used to obtain the mass fractal dimension of the as-made gel network, which is able to differentiate the interfacial effect between surfactant molecules with a slightly denser interphase when a cationic surfactant is used.
•Geopolymer composites were synthesized by emulsion templating with hexadecane and surfactant.•The presence of hexadecane or surfactant has no effect on the geopolymer hardening rate.•The formation of the percolation network is similar in the composites with hexadecane and in pure geopolymer.•Surfactants stabilize the emulsion in the presence of aluminosilicate particles.
•Layered double hydroxide platelets are organo-modified by lignosulfonate (LDH/LS).•LDH/LS are dispersed at nanometric scale into thermoplastic starch.•Preparation of partially bio-based blends of ...polyolefin using LDH/LS–starch mixture.
Layered double hydroxide prepared with lignosulfonate (LDH/LS) can be easily dispersed down to the nanometric scale in thermoplastic starch, at concentration of 1 up to 4wt% of LDH/LS. They can thus be used as a bio-based reinforcing agent of thermoplastic starch. Incorporation of LDH/LS in starch must be done using LDH/LS slurry instead of powder on order to avoid secondary particles aggregation, the water of the paste being used as the starch plasticizer. This reinforced starch was used for preparing a starch–polyolefine composite. LDH/LS–starch nanocomposites were mixed in a random terpolymer of ethylene, butyl acrylate (6%) and maleic anhydride (3%) at concentrations of 20wt% and 40wt%. With a 20% loading of (1wt% LDH/LS in thermoplastic starch), the ternary copolymer is partially bio-based while keeping nearly its original processability and mechanical properties and improving oxygen barrier properties. The use of layered double hydroxides is also removing most odours linked to the lignin phase.
The present paper describes the synthesis and characterization of nanocomposite materials built from the assembly of organic polymers and two-dimensional host materials, particularly reviewing those ...composed of layered double hydroxide (LDH) inorganic frameworks. When the meaning commonly adopted for nanocomposites is narrowed, the system is constituted of sheets lying on top of each other in which covalent forces maintain the chemical integrity and define an interlamellar gap filled up with the polymer guest. The situation is different from an inorganic filler dispersed into a polymeric matrix. The incorporation of polymer between the galleries proceeds via different pathways such as coprecipitation, exchange, in situ polymerization, surfactant-mediated incorporation, hydrothermal treatment, reconstruction, or restacking. The latter method, recently effective via the exfoliation of the LDH layers, appears to be more favorable, in terms of crystallinity, to capture monomer entities than the whole polymer. The nanocomposites are enlisted according to the preparation pathways. It is found that these multicomponent systems are thermally more stable than the pristine inorganic compounds, leading, for example, to potential applications in flame-retardant composites. A large variety of LDH/polymer systems may be tailored considering the highly tunable intralayer composition coupled to the choice of the organic moiety. The paper concludes with a brief discussion underlining the perspectives. Despite their appeal, the polymer/LDH class of nanocomposites has not yet been extensively studied for applications.
