Showing papers on "Mesoporous material published in 2008"
TL;DR: In this paper, high resolution transmission electron microscopy proves the extended two-dimensional character of the condensation motif of graphitic carbon nitride, and a new family of metal nitride nanostructures can also be accessed from the corresponding oxides.
Abstract: Graphitic carbon nitride, g-C3N4, can be made by polymerization of cyanamide, dicyandiamide or melamine. Depending on reaction conditions, different materials with different degrees of condensation, properties and reactivities are obtained. The firstly formed polymeric C3N4 structure, melon, with pendant amino groups, is a highly ordered polymer. Further reaction leads to more condensed and less defective C3N4 species, based on tri-s-triazine (C6N7) units as elementary building blocks. High resolution transmission electron microscopy proves the extended two-dimensional character of the condensation motif. Due to the polymerization-type synthesis from a liquid precursor, a variety of material nanostructures such as nanoparticles or mesoporous powders can be accessed. Those nanostructures also allow fine tuning of properties, the ability for intercalation, as well as the possibility to give surface-rich materials for heterogeneous reactions. Due to the special semiconductor properties of carbon nitrides, they show unexpected catalytic activity for a variety of reactions, such as for the activation of benzene, trimerization reactions, and also the activation of carbon dioxide. Model calculations are presented to explain this unusual case of heterogeneous, metal-free catalysis. Carbon nitride can also act as a heterogeneous reactant, and a new family of metal nitride nanostructures can be accessed from the corresponding oxides.
2,746 citations
TL;DR: By using the unique core-shell microspheres with accessible large pores and excellent magnetic property, a fast removal of microcystins with high efficiency can be achieved.
Abstract: Superparamagnetic microspheres with an Fe3O4@SiO2 core and a perpendicularly aligned mesoporous SiO2 shell were synthesized through a surfactant-templating sol−gel approach. The microspheres possess high magnetization (53.3 emu/g), high surface area (365 m2/g), large pore volume (0.29 cm3/g), and uniform mesopore (2.3 nm). By using the unique core−shell microspheres with accessible large pores and excellent magnetic property, a fast removal of microcystins with high efficiency (>95%) can be achieved.
1,553 citations
TL;DR: Characterization was performed using both manometry and gravimetry in different laboratories for isotherms coupled with microcalorimetry and FTIR to specify the gas-solid interactions in Mesoporous MOFs MIL-100 and MIL-101.
Abstract: Mesoporous MOFs MIL-100 and MIL-101 adsorb huge amounts of CO2 and CH4. Characterization was performed using both manometry and gravimetry in different laboratories for isotherms coupled with microcalorimetry and FTIR to specify the gas—solid interactions. In particular, the uptake of carbon dioxide in MIL-101 has been shown to occur with a record capacity of 40 mmol g−1 or 390 cm3STP cm−3 at 5 MPa and 303 K.
1,055 citations
TL;DR: This Review discusses the application of ordered, large-pore, functionalized mesoporous silicates to immobilize proteins for biocatalysis.
Abstract: Mesoporous silicates (MPS) have an ordered pore structure with dimensions comparable to many biological molecules. They have been extensively explored as supports for proteins and enzymes in biocatalytic applications. Since their initial discovery, novel syntheses methods have led to precise control over pore size and structure, particle size, chemical composition, and stability, thus allowing the adsorption of a wide variety of biological macromolecules, such as heme proteins, lipases, antibody fragments, and proteases, into their structures. This Review discusses the application of ordered, large-pore, functionalized mesoporous silicates to immobilize proteins for biocatalysis.
629 citations
TL;DR: Partly ordered mesoporous alumina with hydrous aluminum nitrate as the precursor exhibits reactant size selectivity in hydrogenation of acetone, D-glucose, and D-(+)-cellobiose as a test reaction, indicating the potential applications in shape-selective catalysis.
Abstract: The facile synthesis of highly ordered mesoporous aluminas with high thermal stability and tunable pore sizes is systematically investigated. The general synthesis strategy is based on a sol-gel process associated with nonionic block copolymer as templates in ethanol solvent. Small-angle XRD, TEM, and nitrogen adsorption and desorption results show that these mesoporous aluminas possess a highly ordered 2D hexagonal mesostructure, which is resistant to high temperature up to 1000 degrees C. Ordered mesoporous structures with tunable pore sizes are obtained with various precursors, different acids as pH adjustors, and different block copolymers as templates. These mesoporous aluminas have large surface areas (ca. 400 m2/g), pore volumes (ca. 0.70 cm3/g), and narrow pore-size distributions. The influence of the complexation ability of anions and hydro-carboxylic acid, acid volatility, and other important synthesis conditions are discussed in detail. Utilizing this simple strategy, we also obtained partly ordered mesoporous alumina with hydrous aluminum nitrate as the precursor. FTIR pyridine adsorption measurements indicate that a large amount of Lewis acid sites exist in these mesoporous aluminas. These materials are expected to be good candidates in catalysis due to the uniform pore structures, large surface areas, tunable pore sizes, and large amounts of surface Lewis acid sites. Loaded with ruthenium, the representative mesoporous alumina exhibits reactant size selectivity in hydrogenation of acetone, D-glucose, and D-(+)-cellobiose as a test reaction, indicating the potential applications in shape-selective catalysis.
615 citations
TL;DR: The application of templating methods to produce zeolite materials with hierarchical bi- or trimodal pore size distributions is reviewed with emphasis on mesoporous materials.
Abstract: The application of templating methods to produce zeolite materials with hierarchical bi- or trimodal pore size distributions is reviewed with emphasis on mesoporous materials. Hierarchical zeolite materials are categorized into three distinctly different types of materials: hierarchical zeolite crystals, nanosized zeolite crystals, and supported zeolite crystals. For the pure zeolite materials in the first two categories, the additional meso- or macroporosity can be classified as being either intracrystalline or intercrystalline, whereas for supported zeolite materials, the additional porosity originates almost exclusively from the support material. The methods for introducing mesopores into zeolite materials are discussed and categorized. In general, mesopores can be templated in zeolite materials by use of solid templating, supramolecular templating, or indirect templating. In this categorization of templating methods, the nature of the interface between the zeolite crystal and the mesopore exactly when...
612 citations
TL;DR: In this paper, the effects of CO 2 treatment on the pore structures of carbon CS15A6 were discussed and the results showed that CO 2 activation leads to better capacitive performances.
563 citations
TL;DR: Results from the self-assembly of block copolymers with ligand-stabilized platinum nanoparticles, leading to lamellar CCM-Pt-4 and inverse hexagonal hybrid mesostructures with high nanoparticle loadings are presented.
Abstract: The synthesis of ordered mesoporous metal composites and ordered mesoporous metals is a challenge because metals have high surface energies that favor low surface areas. We present results from the self-assembly of block copolymers with ligand-stabilized platinum nanoparticles, leading to lamellar CCM-Pt-4 and inverse hexagonal (CCM-Pt-6) hybrid mesostructures with high nanoparticle loadings. Pyrolysis of the CCM-Pt-6 hybrid produces an ordered mesoporous platinum-carbon nanocomposite with open and large pores (>/=10 nanometers). Removal of the carbon leads to ordered porous platinum mesostructures. The platinum-carbon nanocomposite has very high electrical conductivity (400 siemens per centimeter) for an ordered mesoporous material fabricated from block copolymer self-assembly.
555 citations
TL;DR: This work reports on an approach established for group-IV (titanium) and group-V (niobium) oxides, with potential applications to photovoltaic cells and fuel cells, respectively, which overcomes previous limitations and gives direct access to the desired materials in a 'one-pot' synthesis.
Abstract: Direct access to thermally stable and highly crystalline mesoporous transition-metal oxides with uniform pores
554 citations
TL;DR: It is demonstrated how a wide range of crystal morphologies can be realized through such confined growth within 3DOm carbon, synthesized by replication of colloidal crystals composed of size-tunable (about 10-40 nm) silica nanoparticles.
Abstract: Zeolite nanocrystals with three-dimensionally ordered mesoporous structures are important for designing molecularly accessible and selective catalysts. With a single zeolite synthesis procedure, uniform nanocrystals and crystal zeolites with ordered imprinted mesoporosity can now be obtained.
548 citations
TL;DR: Mesoporous Si@carbon core-shell nanowires with a diameter of approximately 6.5 nm were prepared for a lithium battery anode material using a SBA-15 template and demonstrated excellent first charge capacity and retention after 80 cycles.
Abstract: Mesoporous Si@carbon core-shell nanowires with a diameter of approximately 6.5 nm were prepared for a lithium battery anode material using a SBA-15 template. As-synthesized nanowires demonstrated excellent first charge capacity of 3163 mA h/g with a Coulombic efficiency of 86% at a rate of 0.2 C (600 mA/g) between 1.5 and 0 V in coin-type half-cells. Moreover, the capacity retention after 80 cycles was 87% and the rate capability at 2 C (6000 mA/g) was 78% the capacity at 0.2 C.
TL;DR: The key point of this synthesis relies on the occurrence of several high temperature polymerization reactions, where irreversible carbonization reactions coupled with the reversible trimerization of nitriles allow the reorganization of the dynamic triazine network.
Abstract: High surface area organic materials featuring both micro- and mesopores were synthesized under ionothermal conditions via the formation of polyaryltriazine networks. While the polytrimerization of nitriles in zinc chloride at 400 degrees C produces microporous polymers, higher reaction temperatures induce the formation of additional spherical mesopores with a narrow dispersity. The nitrogen-rich carbonaceous polymer materials thus obtained present surface areas and porosities up to 3300 m(2) g(-1) and 2.4 cm(3) g(-1), respectively. The key point of this synthesis relies on the occurrence of several high temperature polymerization reactions, where irreversible carbonization reactions coupled with the reversible trimerization of nitriles allow the reorganization of the dynamic triazine network. The ZnCl2 molten salt fulfills the requirement of a high temperature solvent, but is also required as catalyst. Thus, this dynamic polymerization system provides not only highly micro- and mesoporous materials, but also allows controlling the pore structure in amorphous organic materials.
TL;DR: In this article, mesoporous carbon with homogeneous boron dopant was prepared by co-impregnation and carbonization of sucrose and boric acid confined in mesopores of SBA-15 silica template.
Abstract: Mesoporous carbon with homogeneous boron dopant was prepared by co-impregnation and carbonization of sucrose and boric acid confined in mesopores of SBA-15 silica template. Low-level boron doping shows catalytic effect on oxygen chemisorption at edge planes and alters electronic structure of space charge layer of doped mesoporous carbon. These characteristics are responsible for substantial improvement of interfacial capacitance by 1.5-1.6 times higher in boron-doped carbon than that in boron-free carbon with alkaline electrolyte (6 M KOH) and/or acid electrolyte (I M H2SO4). This finding should be very useful for developing new doped carbon electrode materials for supercapacitors.
TL;DR: The new O-Ti-B-N structure formed on the surface of the photocatalyst is highly active in collecting and separating the charge carriers, thereby greatly enhancing the visible light photocatalytic activity.
Abstract: Add an N: The visible-light absorption of boron-doped mesoporous TiO2 depends strongly on the state of the dopant (see picture), although the activity can be substantially enhanced by additional doping of nitrogen. The new O-Ti-B-N structure formed on the surface of the photocatalyst is highly active in collecting and separating the charge carriers, thereby greatly enhancing the visible light photocatalytic activity.
TL;DR: In this paper, a two-dimensional mesoporous carbon nitride (MCN) with tunable pore diameters was successfully prepared for the first time using SBA-15 materials as templates through a simple polymerization reaction between ethylenediamine (EDA) and carbon tetrachloride (CTC) by a nano hard-templating approach.
Abstract: Two-dimensional mesoporous carbon nitride (MCN) with tunable pore diameters have been successfully prepared for the first time using SBA-15 materials with different pore diameters as templates through a simple polymerization reaction between ethylenediamine (EDA) and carbon tetrachloride (CTC) by a nano hard-templating approach. The obtained materials have been unambiguously characterized using X-ray diffraction (XRD), N2 adsorption, high-resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), high-resolution scanning electron microscopy (HRSEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, and CHN analysis. The results show that the pore diameter of the MCN materials can be easily tuned from 4.2 to 6.4 nm without affecting their structural order. XRD, HRTEM and N2 adsorption results reveal that the materials are structurally well ordered with a two-dimensional porous structure, a high surface area and a large pore volume. It is also demonstrated for the first time that the textural parameters such as the specific pore volume, the specific surface area and the pore diameter, and the nitrogen content of the MCN materials can be controlled by the simple adjustment of the EDA to CTC weight ratio. The carbon to nitrogen ratio of the MCN decreases from 4.3 to 3.3 with increasing EDA to CTC weight ratio from 0.3 to 0.9. The optimum EDA to CTC weight ratio required for fabricating the well-ordered MCN materials with excellent textural parameters and high nitrogen content is around 0.45. The catalytic activity of the materials has been tested in the Friedel-Crafts acylation of benzene using hexanoyl chloride as the acylating agent. The materials are highly active and show a high conversion and 100 % product selectivity to caprophenone.
TL;DR: The fabrication and chemical modifications of porous silicon for biomedical applications, and also the potential advantages of PSi in drug delivery are reviewed.
TL;DR: In this article, a rattle-type hollow magnetic mesoporous sphere (HMMS) with Fe3O4 particles encapsulated in the cores of mesopore silica microspheres has been successfully fabricated by sol-gel reactions on hematite particles followed by cavity generation with hydrothermal treatment and H2 reduction.
Abstract: A novel kind of rattle-type hollow magnetic mesoporous sphere (HMMS) with Fe3O4 particles encapsulated in the cores of mesoporous silica microspheres has been successfully fabricated by sol–gel reactions on hematite particles followed by cavity generation with hydrothermal treatment and H2 reduction. Such a structure has the merits of both enhanced drug-loading capacity and a significant magnetization strength. The prepared HMMSs realize a relatively high storage capacity up to 302 mg g−1 when ibuprofen is used as a model drug, and the IBU–HMMS system has a sustained-release property, which follows a Fick's law.
TL;DR: In this paper, individual SnO2 nanoparticles were incorporated into a carbon matrix produced by hydrothermal carbonization, and assembled into mesoporous SNO2 microspheres with good electrochemical performance regarding Li storage.
Abstract: Individual SnO2 nanoparticles were incorporated into a carbon matrix produced by hydrothermal carbonization. After the removal of the carbon, the nanoparticles assembled into mesoporous SnO2 microspheres with good electrochemical performance regarding Li storage.
TL;DR: In this paper, two different reaction pathways over Co(3)O(4)-CeO(2) and Pd/Co(3,O,4)-Co(2), with varying compositions were proposed.
TL;DR: In this article, the synthesis of ordered mesoporous polymers and carbons based on the supramolecular aggregates as templates is summarized and the morphological control and functionalization of these materials are briefly summarized.
Abstract: Supramolecular aggregateʼs self-assembling approach has derived diverse mesostructured inorganic solids. Recent progresses involve ordered mesoporous carbonaceous frameworks. This review paper summarizes the synthesis of ordered mesoporous polymers and carbons based on the supramolecular aggregates as templates. Block copolymers are mainly introduced here. Both the aggregates of block copolymers themselves and the assembling with thermosetting resins have the abilities to organize ordered mesostructures. The understanding of the synthesis is on the formation of supramolecular arrangement of molecules, templating, cross-linking, removal of templates, and carbonization. In addition, the morphological control and the functionalization of ordered mesoporous carbonaceous materials are briefly summarized. The attractive mesoporous carbonaceous materials offer great opportunities in catalysis, water purification, electrodes, adsorbents, gas storage, aero-space, etc.
TL;DR: A large-scale self-etching approach for the synthesis of monodispersed mesoporous F-TiO2 hollow microspheres exhibited ease for the concurrent membrane filtration and photocatalysis, providing high potential for engineering application in advanced water treatment.
Abstract: We report a large-scale self-etching approach for the synthesis of monodispersed mesoporous F−TiO2 hollow microspheres. The self-etching derived from HF was elucidated by the morphology, chemical composition, and crystal size evolutions from solid to hollow microspheres with the increase in the concentration of H2SO4. The resulting TiO2 hollow microspheres exhibited ease for the concurrent membrane filtration and photocatalysis, providing high potential for engineering application in advanced water treatment, for not only increasing water production but also improving water quality.
TL;DR: Amine-functionalized MCM-41 micro-spheres were found to show a significantly slower drug release rate than irregularly shaped powders, which should facilitate drug delivery control over a longer time period.
TL;DR: In this paper, the main types of nanoporous adsorbents for water are identified and described with emphasis on the mechanism of adsorption, modification, improvement of the water sorption capacity, possible regeneration, and stabilization.
TL;DR: In this paper, a mesoporous carbon (S-C) composites were tested in a novel ionic liquid electrolyte consisting of 1-ethyl-3methylimidazolium bis(trifluoromethanesulfonyl)imide and lithium bistrifluorsulfonimidate.
TL;DR: In this paper, the possibilities of using hard templates to create nanostructured "soft" materials, for example, polymer networks, carbon nitrides, or carbonaceous materials, which are still organic in their nature, are described.
Abstract: This review describes the possibilities of using hard templates to create nanostructured “soft” materials, for example, polymer networks, carbon nitrides, or carbonaceous materials, that is, materials which are still organic in their nature. Examples are given for the whole range of hard templates described in the literature, starting from silica nanoparticles, zeolites, and periodic mesoporous silicas to aluminum oxide membranes and colloidal crystals.
TL;DR: In this paper, three mesoporous silica materials with different pore sizes and pore connectivity were prepared and functionalized with aminopropyl (AP) ligands by post-synthesis treatment.
TL;DR: The one-pot synthesis of alumina-supported metal oxides via self-assembly of a metal precursor and aluminum isopropoxide in the presence of triblock copolymer (as a structure directing agent) is described in detail for nickel oxide, representing an important step toward the facile and reproducible synthesis of ordered mesoporous aluminium-supported materials.
Abstract: The one-pot synthesis of alumina-supported metal oxides via self-assembly of a metal precursor and aluminum isopropoxide in the presence of triblock copolymer (as a structure directing agent) is described in detail for nickel oxide. The resulting mesoporous mixed metal oxides possess p6 mm hexagonal symmetry, well-developed mesoporosity, relatively high BET surface area, large pore widths, and crystalline pore walls. In comparison to pure alumina, nickel aluminum oxide samples exhibited larger mesopores and improved thermal stability. Also, long-range ordering of the aforementioned samples was observed for nickel molar percentages as high as 20%. The generality of the recipe used for the synthesis of mesoporous nickel aluminum oxide was demonstrated by preparation of other alumina-supported metal oxides such as MgO, CaO, TiO 2, and Cr 2O 3. This method represents an important step toward the facile and reproducible synthesis of ordered mesoporous alumina-supported materials for various applications where large and accessible pores with high loading of catalytically active metal oxides are needed.
TL;DR: In this paper, a Bi2O3/TiO2 nanocrystalline with ordered mesoporous structure is synthesized by ab evaporation-induced self-assembly method.
Abstract: Bi2O3/TiO2 nanocrystallines with ordered mesoporous structure are synthesized by ab evaporation-induced self-assembly method. During liquid-phase photocatalytic degradation of p-chlorophenol under visible illumination (λ > 420 nm), this catalyst exhibits high activity owing to the synergetic effects of both the Bi2O3-photosensitization and the unique structural characteristics. The Bi2O3-photosensitization of TiO2 could extend the spectral response from UV to visible area, making the Bi2O3/TiO2 photocatalyst easily activated by visible lights. The ordered mesoporous channels facilitate the diffusion of reactant molecules. Meanwhile, the high surface area could enhance the Bi2O3 dispersion, the light harvesting, and the reactant adsorption. Furthermore, the highly crystallized anatase may promote the transfer of photoelectrons from bulk to surface and thus inhibit their recombination with photoholes, leading to enhanced quantum efficiency.
TL;DR: It was found that the development of an ordered mesoporous structure and the control of the number of micropores are two important strategies for optimising electrode material properties for electrosorptive deionisation.