MgCaAl layered double hydroxide-derived mixed metal oxide porous hexagonal nanoplatelets for CO sorption.

Porous hexagonal nanoplatelets of mixed metal oxide (MMO) derived from the calcination of MgAl layered double hydroxide exhibits a CO sorption capacity of 1.99 mmol g at 30 °C, with a retention of 87% sorption capacity over 10 carbonation-decarbonation cycles and a CO sorption capacity of 1 mmol g at 200 °C with a 40% increase in capacity over 10 cycles. The high sorption capacity is attributed to the porous nanoplatelet structure of the MMO with a BET surface area of 115 m g, which enables increased CO diffusion.

Anion Exchange Reactions of 3R-MgAl-Carbonate-LDH: Comparison with the 3R Analogue and Formation of 3R Polytype of MgAl-LDH with Other Interlayer Anions.

Anion exchange reactions with several monovalent anions and a divalent sulfate anion could be successfully carried out on 3R polytype of magnesium aluminum LDH containing interlayer carbonate ions by refluxing the carbonate-LDH in 1-butanol with ammonium salt of the desired anion. The reaction was similar to what was observed in the case of 3R polytype (Bhojaraj et al., , , 20072-20079) in that here too the reaction occurs topotactically resulting in 3R polytypes of LDHs in the cases of chloride and bromide anions.

Separation of amino acids by selective sorption through reconstructive intercalation in calcined MgAl-layered double hydroxide.

Mg-Al layered double hydroxide (MgAl-LDH) exhibits selectivity in the intercalation of amino acids (AAs). When the MgAl-LDH derived mixed metal oxide was treated with different mixtures of AAs, preferential sorption of one AA over the other(s) was observed as indicated by XRD analysis of the products and HPLC analysis of the interlayer AA contents in the products. The order of preference was aspartic acid, glutamic acid (acidic AAs) > glycine, alanine (neutral AAs) > hystidine, and arginine (basic AAs).

The Effect of Reactive Electric Field-Assisted Sintering of MoS/BiTe Heterostructure on the Phase Integrity of BiTe Matrix and the Thermoelectric Properties.

In this work, a series of BiTe/X mol% MoS (X = 0, 25, 50, 75) bulk nanocomposites were prepared by hydrothermal reaction followed by reactive spark plasma sintering (SPS). X-ray diffraction analysis (XRD) indicates that the native nanopowders, comprising of BiTe/MoS heterostructure, are highly reactive during the electric field-assisted sintering by SPS. The nano-sized MoS particles react with the BiTe plates matrix forming a mixed-anion compound, BiTeS, at the interface between the nanoplates.

Induced 2H-Phase Formation and Low Thermal Conductivity by Reactive Spark Plasma Sintering of 1T-Phase Pristine and Co-Doped MoS Nanosheets.

Pristine and Co-doped MoS nanosheets, containing a dominant 1T phase, have been densified by spark plasma sintering (SPS) to produce a nanostructured arrangement. The structural analysis by X-ray powder diffraction revealed that the reactive sintering process transforms the 1T-MoS nanosheets into their stable 2H form despite a significantly reduced sintering temperature and time testifying to the fast kinetics of phase change. Together with the phase conversion, the SPS process promoted a strong texturing of the nanosheets, which drives additional scattering processes and alters the electronic and thermal transport properties.

Hierarchically Porous, Biphasic, and C-Doped TiO for Solar Photocatalytic Degradation of Dyes and Selective Oxidation of Benzyl Alcohol.

Macroporous TiO monoliths were synthesized by self-sustained combustion reactions of molded pellets made up of a mixture of TiCl as a precursor, urea as a fuel, ammonium nitrate as an oxidizer, and starch as a binder. The porous TiO monoliths were found to be a heterostructure of anatase and rutile phases, in addition to being doped with carbon. Variation in the amount of starch yielded porous monoliths of different anatase-rutile ratios (increasing rutile component from 0 to 40%) but comparable Brunauer-Emmett-Teller (BET) surface area (∼30 m g).

Solvent-Mediated and Mechanochemical Methods for Anion Exchange of Carbonate from Layered Double Hydroxides Using Ammonium Salts.

Deintercalation of carbonate from layered double hydroxides (LDH) followed by intercalation of another anion (decarbonative intercalation) is a good method for the synthesis of crystalline LDH with different intercalated anions. We have carried out decarbonative intercalation of halides, nitrate, acetate, and sulfate by refluxing the carbonate-LDH with the corresponding ammonium salt in 1-butanol to obtain ordered LDH incorporating the desired anion. The crystallinity of the precursor LDH is retained in the anion-exchanged products, making this reaction a useful tool to prepare ordered LDH containing various anions.

Microwave-Assisted Synthesis of Porous Aggregates of CuS Nanoparticles for Sunlight Photocatalysis.

Solvated two-dimensional nanosheets of copper hydroxy dodecylsulfate in 1-butanol react with thiourea under microwave irradiation to yield surfactant-free porous aggregates of CuS nanoparticles. These aggregates exhibit excellent photocatalytic activity toward degradation of methylene blue, methyl orange, and 4-chlorophenol in natural sunlight. While the high surface area (14.

Magnetic Co-Doped MoS Nanosheets for Efficient Catalysis of Nitroarene Reduction.

Co-doped MoS nanosheets have been synthesized through the hydrothermal reaction of ammonium tetrathiomolybdate and hydrazine in the presence of cobalt acetate. These nanosheets exhibit a dominant metallic 1T phase with cobalt ion-activated defective basal planes and S-edges. In addition, the nanosheets are dispersible in polar solvents like water and methanol.

Preparation of titanate nanosheets and nanoribbons by exfoliation of amine intercalated titanates.

Amine intercalated titanates were synthesized by direct exchange of potassium ions of K2Ti4O9 by alkyl ammonium ions of various alkyl chain lengths. These intercalated solids exfoliate well in alcohols of different alkyl chain lengths and non-polar solvents such as toluene and hexane to yield colloidal dispersions of titanate nanosheets. The longer the alkyl chain of the intercalated amine the better the exfoliation of the intercalated titanate in long chain alcohols and non-polar solvents.

Cobalt hydroxide/oxide hexagonal ring-graphene hybrids through chemical etching of metal hydroxide platelets by graphene oxide: energy storage applications.

The reaction of β-Co(OH)2 hexagonal platelets with graphite oxide in an aqueous colloidal dispersion results in the formation of β-Co(OH)2 hexagonal rings anchored to graphene oxide layers. The interaction between the basic hydroxide layers and the acidic groups on graphene oxide induces chemical etching of the hexagonal platelets, forming β-Co(OH)2 hexagonal rings. On heating in air or N2, the hydroxide hybrid is morphotactically converted to porous Co3O4/CoO hexagonal ring-graphene hybrids.

Chemical unzipping of WS2 nanotubes.

WS2 nanoribbons have been synthesized by chemical unzipping of WS2 nanotubes. Lithium atoms are intercalated in WS2 nanotubes by a solvothermal reaction with n-butyllithium in hexane. The lithiated WS2 nanotubes are then reacted with various solvents--water, ethanol, and long chain thiols.

Exfoliation of copper hydroxysalt in water and the conversion of the exfoliated layers to cupric and cuprous oxide nanoparticles.

P-aminobenzoate-intercalated copper hydroxysalt was prepared by coprecipitation at high pH (∼12). As the pH was reduced to ∼7 on washing with water, the development of partial positive charge on the amine end of the intercalated anion caused repulsion between the layers leading to delamination and colloidal dispersion of monolayers of copper hydroxysalt in water. The dispersed copper hydroxysalt monolayers were used as precursors for the synthesis of copper(I)/(II) oxide nanoparticles at room temperature.

Near 100% selectivity in anion exchange reactions of layered zinc hydroxy nitrate.

The anionic clay, zinc hydroxy nitrate was found to selectively intercalate fluoride ions from a mixture of halide ions and chloride ions from a mixture of chloride, bromide and iodide ions. In a binary mixture of chloride and bromide ions, the selectivity for chloride ions was very high (94%) even when the bromide concentration was eight times in excess. The selectivity was achieved in both concentrated and dilute salt solutions.

Functionalized-graphene modified graphite electrode for the selective determination of dopamine in presence of uric acid and ascorbic acid.

Graphene is chemically synthesized by solvothermal reduction of colloidal dispersions of graphite oxide. Graphite electrode is modified with functionalized-graphene for electrochemical applications. Electrochemical characterization of functionalized-graphene modified graphite electrode (FGGE) is carried out by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).

Layer-by-layer composite of anionic and cationic clays by metathesis.

An alternately stacked layer-by-layer composite of oppositely charged layered solids was obtained by solvothermal treatment of the monolayer colloidal dispersions of dodecylsulfate intercalated nickel aluminum LDH and cetyl trimethylammonium intercalated smectite in 1-octanol. This composite shows altered thermal decomposition behavior compared to the parent solids. On heating the LDH component of the composite decomposes to NiO, while the layer structure of the cationic clay is retained up to 800°C.

Synthesis and anion-exchange reactions of a new anionic clay, α-magnesium hydroxide.

A new anionic clay, α-magnesium hydroxide, was synthesized by hydrolysis of magnesium acetate in propylene glycol. The structure of this α-hydroxide is similar to that of hydrotalcites. It consists of positively charged magnesium hydroxide layers arising out of partial protonation of the hydroxyl groups of the [Mg(OH)(2)] layers and loosely held anions in the interlayer region.

Exfoliation of alpha-hydroxides of nickel and cobalt in water.

p-Aminobenzoate ion intercalated alpha-hydroxides of nickel/cobalt were synthesized by precipitation using ammonia (pH= approximately 12). Aqueous colloidal suspension of alpha-hydroxide of nickel/cobalt was obtained on washing the precipitate as the pH was reduced to approximately 7. The development of partial positive charge on the amine end of the intercalated anion causes repulsion between the layers leading to exfoliation and colloidal suspension of monolayers in water.

Intracrystalline oxidation of thiosulfate-intercalated layered double hydroxides.

Thiosulfate-intercalated zinc-aluminum LDH was prepared by anion exchange reaction. The interlayer thiosulfate ions of this LDH could be quantitatively oxidized to tetrathionate ions using iodine and sulfate ions using H2O2. Both of these intracrystalline reactions are topotactic in nature.

Delamination of surfactant-intercalated brucite-like hydroxy salts of cobalt and copper and solvothermal decomposition of the resultant colloidal dispersions.

Surfactant anion intercalated hydroxy salts of copper and cobalt of the formula M(OH)2- x (surf)x.mH2O [M = Cu, Co; surf = dodecyl sulfate, dodecyl benzene sulfonate, and x = 0.5 for Cu and 0.

Graphite oxide-intercalated anionic clay and its decomposition to graphene-inorganic material nanocomposites.

A graphite oxide-intercalated anionic clay (nickel zinc hydroxysalt) has been prepared using the aqueous colloidal dispersions of negatively charged graphite oxide sheets and aminobenzoate-intercalated anionic clay layers as precursors. When the two colloidal dispersions are reacted, the interlayer aminobenzoate ions are displaced from the anionic clay and the negatively charged graphite oxide sheets are intercalated between the positively charged layers of the anionic clay. The thermal decomposition of the intercalated solid at different temperatures yields graphene-metal oxide/metal nanocomposites.

Interstratification of trioctahedral and dioctahedral smectites through delamination and costacking.

Trioctahedral and dioctahedral organosmectites delaminate in 1-octanol to give stable monolayer colloidal dispersions. Addition of acetone to a mixture of these colloidal dispersions yields a composite of the two clays. Layers of the two smectites are interstratified in the composite.

Ferrimagnetic nanogranular Co3O4 through solvothermal decomposition of colloidally dispersed monolayers of alpha-cobalt hydroxide.

Co3O4 nanoparticles of 35 nm with a cauliflower-like morphology were obtained when a monolayer colloidal dispersion of dodecyl sulfate intercalated alpha-cobalt hydroxide in butanol was subjected to solvothermal hydrolytic decomposition. The nanogranular particles exhibit weakly ferromagnetic properties in contrast with both bulk and dispersed nanoparticulate Co3O4.