Search results for "Hydroxides"

Spontaneous Magnetization in Ni−Al and Ni−Fe Layered Double Hydroxides

2008

Layered double hydroxides containing paramagnetic Ni (II) and diamagnetic/paramagnetic Al (III)/Fe (III) ions have been prepared and characterized. Ni 2Al(OH) 6(NO 3). nH 2O ( 1), Ni 2Fe(OH) 6(NO 3). nH 2O ( 2), Ni 2Fe(OH) 6(C 6H 8O 4) 0.5. nH 2O ( 3), and Ni 2Fe(OH) 6(C 10H 16O 4) 0.5. nH 2O ( 4) were prepared by coprecipitation at controlled pH as polycrystalline materials with the typical brucite-like structure, with alternating layers of hydroxide and the corresponding anions, which determine the interlayer separation. Magnetic studies show the appearance of spontaneous magnetization between 2 and 15 K for these compounds. Interestingly, the onset temperature for spontaneous magnetizati…

Cover Feature: Boosting the Supercapacitive Behavior of CoAl Layered Double Hydroxides via Tuning the Metal Composition and Interlayer Space (Batteri…

2020

Alkoxide-intercalated NiFe-layered double hydroxides magnetic nanosheets as efficient water oxidation electrocatalysts

2016

Alkoxide-intercalated NiFe-layered double hydroxides were synthesized via the nonaqueous methanolic route. These nanoplatelets exhibit high crystalline quality as demonstrated by atomic resolution scanning transmission electron microscopy combined with electron energy-loss spectroscopy. Moreover, the presence of the alkoxide moieties has been unambiguously demonstrated by means of thermogravimetric analysis coupled to a mass spectrometer. These NiFe-LDHs can be exfoliated in water or organic solvents and processed into homogeneous ultra-thin films (< 3nm thick) with the assistance of O2-plasma. The study of their behaviour as water oxidation electrocatalysts has shown an outstanding perf…

Fundamental Insights into the Covalent Silane Functionalization of NiFe Layered Double Hydroxides

2020

Layered double hydroxides (LDHs) are a class of 2D anionic materials exhibiting wide chemical versatility and promising applications in different fields, ranging from catalysis to energy storage and conversion. However, the covalent chemistry of this kind of 2D materials is still barely explored. Herein, the covalent functionalization with silanes of a magnetic NiFe-LDH is reported. The synthetic route consists of a topochemical approach followed by anion exchange reaction with surfactant molecules prior to covalent functionalization with the (3-aminopropyl)triethoxysilane (APTES) molecules. The functionalized NiFe-APTES was fully characterized by X-ray diffraction, infrared spectroscopy, e…

Structural Characterisation of Complex Layered Double Hydroxides and TGA-GC-MS Study on Thermal Response and Carbonate Contamination in Nitrate- and …

2015

Layered double hydroxides (LDHs) are versatile materials used for intercalating bioactive molecules in the fields of pharmaceuticals, nutraceuticals and cosmetics, with the purpose of protecting them from degradation, enhancing their water solubility to increase bioavailability and improving their pharmacokinetic properties and formulation stability. Moreover, LDHs are used in various technological applications to improve stability and processability. The crystal chemistry of hydrotalcite-like compounds was investigated by X-ray powder diffraction (XRPD), automated electron diffraction tomography (ADT) and thermogravimetric analysis (TGA)-GC-MS to shed light on the mechanisms involved in io…

Magnetic materials based on layered double hydroxides: chemical design, processing and electrochemical applications

2018

Tras el descubrimiento del grafeno en 2004, los materiales bidimensionales han generado un interés creciente por parte de la comunidad científica que se prolonga hasta nuestros días. Junto a este material constituido por delgadas láminas de carbono, también existen materiales bidimensionales de naturaleza inorgánica entre los que predominan aquellos basados en fuerzas de van der Waals. Dicalcogenuros metálicos, fósforo negro o antimoneno son algunos de estos ejemplos. Sin embargo, también existen materiales 2D formados por láminas iónicas, donde son las fuerzas electrostáticas las que ejercen un papel fundamental en cuanto a la organización y estructura de dichos sistemas. Este es el caso d…

Influence of antioxidants intercalated layered double hydroxides (AO-LDHs) on the thermo-oxidative stability of pla and pe based nanocomposites

2016

Layered double hydroxides (LDHs) are excellent host matrices for storage and delivery of antioxidants (AOs).

Effects of phenolic-like intercalated layered double hydroxides on poly(lactic acid) based nanocomposites

2015

Two phenolic-like antioxidants (AOs), 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate and 6-hydroxy-2,5,7,8-tetrametilcromano-2-carboxylate anions, were intercalated by anion exchange in layered double hydroxides (LDHs). The two AO-LDHs were dispersed by ultrasound-assisted solution mixing in poly(lactic acid) (PLA) and the thermal oxidation stability of the composites was evaluated following the variation of the molecular weight by SEC, after a controlled aging process, and determining the oxidation induction time (OIT) by DSC. The results evidenced that the intercalation of both the AO molecules within the LDH galleries prevent their own thermal and thermo-oxidative degradation as well a…

On Demand One-Pot Mild Preparation of Layered Double Hydroxides and Their Hybrid Forms: Advances through the Epoxide Route.

2019

Epoxide ring opening driven alkalinization process was explored with the aim of preparing layered double hydroxide (LDH) phases on demand, at room temperature. Employing iodide as nucleophilic agent, the precipitation reaction can be driven under much lower halide concentrations. This scenario favors the selective intercalation of concomitant bulky oxo anions as nitrate or perchlorate in the LDH products, allowing for the one-pot synthesis of an LDH able to delaminate in formamide. Even large dicarboxylic acids, - O2 C-(CH2 )n -CO2 - , with n up to 8, can be quantitively intercalated within the growing LDH phase, providing a versatile one-pot route for hybrid LDHs as well. Under the mild co…

Progress in Understanding of the Interactions between Functionalized Polyolefins and Organo-Layered Double Hydroxides

2013

The dispersion of organo-layered double hydroxides (O-LDH) in functionalized polyolefins (POs) is investigated. Two different polyethylene matrices (maleic anhydride (MAH) and diethyl maleate functionalized) are tested and a hydrogenated fatty acid modified LDH is used. The attention is focused on evidencing the interaction between the functional groups of the polymer and the O-LDH through FT-IR. Moreover, a combination of solvent fractionation, morphological, and rheological characterizations enables to gain a deeper insight into the structure of these composites. In particular, the formation of bridging bonds between the particles and MAH functionalized macromolecules is assumed, possibly…