Two-dimensional Galleries Research Articles

Confined Structures and Selective Mass Transport of Organic Liquids in Graphene Nanochannels

Selective transport of liquids is an important process in the energy and environment industry. The increased energy consumption and the demands of clean water and fossil fuels have urged the development of high-performance membrane technologies. Nanoscale channels with the critical size for molecular sieving and atomistically smooth walls for significant boundary slippage are highly promising to balance the tradeoff between permeability and selectivity. In this work, we explore the molecular structures and dynamics of organic solvents and water, which are confined within nanoscale two-dimensional galleries between graphene or graphene oxide sheets. Molecular dynamics simulation results show that the layered order and significant interfacial slippage are universal for all molecular liquids, leading to notable flow enhancement for channels with a width of few nanometers, in the order of ethylene glycol > butanol > ethanol > hexane > toluene > water > acetone. The extracted dependence of permeability, selectivity on the channel width, and properties of molecular liquids clarify the underlying mechanisms of selective mass transport in nanofluidics, which help to understand and control the filtration and separation processes of molecular liquids. The performance of graphene oxide membranes for permeation and filtration is finally discussed based on the calculated flow resistance for pressure-driven flow or molecular diffusivity for diffusive flow, as well as the solubility and wettability of membranes.

Molecular-Level Heterostructures Assembled from Titanium Carbide MXene and Ni–Co–Al Layered Double-Hydroxide Nanosheets for All-Solid-State Flexible Asymmetric High-Energy Supercapacitors

Unique layered Ti3C2/Ni–Co–Al layered double hydroxide (LDH) heterostructures alternatively stacked with molecular-level nanosheets are for the first time synthesized by a facile liquid-phase cofeeding and electrostatic attraction heteroassemble strategy between negatively charged Ti3C2 and positively charged Ni–Co–Al-LDH nanosheets. The molecular-level Ti3C2/Ni–Co–Al-LDH heterostructures possessing the merits of both conductive and pseudocapacitive components can show greatly enhanced dynamic behavior in Faradaic reaction, which is significant for obtaining a high power density. Electrons penetrate in Ti3C2 layers, while ions diffuse rapidly along two-dimensional galleries, displaying the shortest diffusion pathway and highest efficiency for charge transfer. The Ti3C2/Ni–Co–Al-LDH heterostructure exhibits a specific capacitance of 748.2 F g–1 at current density of 1 A g–1, showing an enhanced rate capacity. Importantly, a maximum energy density of 45.8 Wh kg–1 is obtained when Ti3C2/Ni–Co–Al-LDH acts as ...

Improvement in the emission properties of a luminescent anionic dye intercalated between the lamellae of zinc hydroxide-layered

A luminescent green anionic dye, 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium, has been intercalated between the layers of the zinc hydroxide-layered (here named as ZHL-layered-NO3) using an anion exchange technique to produce new luminescent organic–inorganic hybrid materials with interesting photoemission properties. X-ray diffraction, FTIR, UV–vis spectroscopic and scanning electron microscopic studies have shown the incorporation of the luminescent anionic dye between the layers of the inorganic host. X-ray diffraction studies revealed increases in the basal spacing of ZHL-layered hybrid after the intercalation of the green dye using different time intercalation. The interlayer spacing increased from 0.98nm in the pristine ZHL-layered NO3 to 3.54, 3.18 and 3.62nm in the ZHL-layered/Py-SO3−3 composites at 12, 24 and 48h of time intercalation, respectively. Photophysical properties of these new luminescent hybrids (ZHL-layered/Py-SO3−3) were also investigated using the UV–vis absorption, steady-state and dynamic fluorescence spectroscopies. All hybrid materials presented UV–vis absorption bands and photoemission at green region due to the presence of the anionic dye in the galleries of the inorganic layered. For the material produced at 12h of time intercalation, a higher quantum yield photoluminescence (ϕPL=13.0%) was observed compared to the pure dye solid (ϕPL=1.0%). This result was attributed to the confinement of the anionic species in the host two-dimensional gallery. These observations open new opportunities for the use of this organic dye immobilized in alternative layered compound for electronic devices or for sensors.

Using VBA Technology to Develop Two-Dimensional Gallery System of Components of Injection Moulds for Plastics

The development process and method of using VBA technology to develop two-dimensional gallery system of components of injection moulds for plastics taking ejector pin for example is described in detail, which includes establishing parameters database of components, design and calling of user interface, program and menu. The two-dimensional gallery system of components of injection moulds for plastics developed in AutoCAD can generate two-dimensional drawing automatically with the design parameters that user selects and it is convenient for user to plot.

Synthesis of graphene nanosheets with good control over the number of layers within the two-dimensional galleries of layered double hydroxides

Graphene nanosheets have been generated in the confined space of the two-dimensional galleries of a layered double hydroxide (LDH) and good control over the number of graphene layers can be achieved by adjusting the amounts of intercalated carbon source.

Effect of confinement of anionic organic ultraviolet ray absorbers into two-dimensional zinc hydroxide nitrate galleries

Anionic ultraviolet (UV) ray absorbers (4-methoxybenzoate, N-acetylanthranilate, 4-methoxycinnamate and 4,4'-diamino-2,2'-stilbenedisulfonate) were intercalated into zinc hydroxide nitrate, either by direct alkaline co-precipitation or topotactic exchange reactions. The intercalation was confirmed by X-ray powder diffractometry (XRPD), Fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA/DTA), scanning electron microscopy (SEM), selected area electron diffraction (SAED), elemental analysis and ultraviolet visible (UV-Vis) spectroscopy. In the co-precipitation reactions full intercalation was achieved, while during the exchange reactions nitrate anions were not completely replaced by the organic anions. After the intercalation, the UV absorption capacity was similar to that of the solid salts and acids, the effect being attributed to the confinement of the anionic species in the host two-dimensional gallery. This observation opens new opportunities for the use of organic anions immobilized in alternative layered matrixes for the formulation of sunscreens.

Thermally Stable Luminescent Composites Fabricated by Confining Rare Earth Complexes in the Two-Dimensional Gallery of Titania Nanosheets and Their Photophysical Properties

Fluorescent composite materials of exfoliated titania nanosheets, Ti(0.91)O(2), and rare earth (RE) complexes, Eu(phen)(2)Cl(3).2H(2)O and Tb(phen)(2)Cl(3).2H(2)O (phen = 1,10-phenanthroline), were synthesized via flocculation between them. X-ray diffraction measurements and transmission electron microscopy observations confirmed a restacked lamellar structure for the composites, and elemental analysis revealed a high RE complex content of 15 wt %. The decomposition temperature of the complexes trapped in the composites was improved to 420 degrees C from 250 degrees C for the free form. The restacked composite composed of Ti(0.91)O(2) nanosheets and Eu(phen)(2) exhibited characteristic red emission from the complex, while the composite with Tb(phen)(2) gave featureless emission originated from the ligand. This phenomenon can be explained by a shift of triplet state level of the ligand after encapsulation in the host titania nanosheets. The quantum yield of europium complex in the composite was enhanced 1.6 times more than that of the pure complex.

Cooperative Host−Guest Recognition in Crystalline Clathrates: Steric Guest Ordering by Molecular Gears

Supramolecular host frameworks consisting of guanidinium (G) and 4,4‘-biphenyldisulfonate (BPDS) ions include a diverse variety of aromatic guests to afford clathrates with the composition (G)2BPDS·(guest). Single-crystal X-ray diffraction reveals that these materials have a bilayer architecture in which the BPDS ions serve as pillars that connect opposing two-dimensional hydrogen-bonded networks of guanidinium and sulfonate ions, resulting in the formation of galleries with one-dimensional pores occupied by the guests. The solid-state structures of clathrates derived from various monosubstituted benzene guests (C6H5X; X = Cl, CH3, Br, I) and disubstituted isomers (o,m,p-YC6H5X; X, Y = Cl, CH3, Br) reveal cooperative host−guest and guest−guest interactions that affect the observed pore structure and molecular ordering in the two-dimensional galleries. The pore heights and corresponding pore sizes decrease with the introduction of halogenated guests relative to their hydrocarbon analogues, suggesting attra...

A New Redox Host for Intercalative Polymerization: Insertion of Polyaniline into α-RuCl3

α-RuCl3 is a new host for polymer intercalation using an in situ redox intercalative polymerization recaction. With the aid of ambient oxygen, aniline molecules get oxidatively polymerized by the Ru3+ centers of the inorganic host and enter the two-dimensional galleries. An electrically conductive lamellar nanocomposite between polyaniline and RuCl3 results in which the layers exhibit mixed Ru2+/3+ valency. The driving force comes from the formation of thermodynamically stable low spin Ru2+ centers,

Zirconia-pillared tetrasilicic fluoromica

Zirconia-pillared tetrasilicic fluoromicas are prepared from sodium tetrasilicic mica, Na-[Mg[sub 2.5]Si[sub 4]O[sub 10]F[sub 2]], using a commercial zirconyl acetate solution as the source of the zirconium polyoxocation pillars. Reproducible results are conveniently obtained without any preliminary heating of the pillaring solution, and the pillaring reaction is performed at ambient temperature. The resulting zirconia-pillared mica has a consistently higher crystallinity and layer spacing than pillared clays prepared from zirconyl chloride solutions adn shows significantly higher thermal stability, an important factor in potential catalytic applications. Zirconia-pillared tetrasilicic fluoromica is a microporous material containing two-dimensional galleries with a height of 11 [angstrom]. The surface area is high, about 300 m[sup 2]/g. After treatment in steam at 760[degrees]C for 17 h, the surface area is reduced only to [approximately]200 m[sup 2]/g. Thus, very small particles of ZrO[sub 2] dispersed between 10-[angstrom]-thick mica layers have been stabilized. 39 refs., 7 figs., 3 tabs.