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1.
Hydrothermally stable thioether‐bridged mesoporous materials have been synthesized by one‐step co‐condensation of 1,4‐bis(triethoxysily)propane tetrasulfide (TESPTS) with tetramethoxysilane (TMOS) using cetyltrimethylammonimum bromide (CTAB) as the surfactant in basic conditions. The ordered mesoporous materials can be formed with a wide range of thioether concentrations in the mesoporous framework, as is seen by X‐ray diffraction (XRD) characterization. The results of N2 sorption and transmission electron microscopy (TEM) reveal that the materials synthesized with TESPTS/TMOS molar ratios in the range 1:8–1:3 have extensive structural defect holes in the nanochannels. All materials exhibit enhanced hydrothermal stability, which is in proportion to the concentration of thioether bridging in the mesoporous framework. The thioether‐functionalized mesoporous materials are efficient adsorbents for removing Hg2+ and phenol from waste water. The Hg2+‐adsorption capacity of the material can be as high as 1500 mg g–1. 相似文献
2.
Nanocast carbon monoliths exhibiting a three‐ or four‐modal porosity have been prepared by one‐step impregnation, using silica monoliths containing a bimodal porosity as the scaffold. Combined volume and surface templating, together with the controlled synthesis of the starting silica monoliths used as the scaffold, enables a flexible means of pore‐size control on several length scales simultaneously. The monoliths were characterized by nitrogen sorption, scanning electron microscopy, transmission electron microscopy, and mercury porosimetry. It is shown that the carbon monoliths represent a positive replica of the starting silica monoliths on the micrometer length scale, whereas the volume‐templated mesopores are a negative replica of the silica scaffold. In addition to the meso‐ and macropores, the carbon monoliths also exhibit microporosity. The different modes of porosity are arranged in a hierarchical structure‐within‐structure fashion, which is thought to be optimal for applications requiring a high surface area in combination with a low pressure drop over the material. 相似文献
3.
Nanometer‐sized surfactant‐templated materials are prepared in the form of stable suspensions of colloidal mesoporous silica (CMS) consisting of discrete, nonaggregated particles with dimensions smaller than 200 nm. A high‐yield synthesis procedure is reported based on a cationic surfactant and low water content that additionally enables the adjustment of the size range of the individual particles between 50 and 100 nm. Particularly, the use of the base triethanolamine (TEA) and the specific reaction conditions result in long‐lived suspensions. Dynamic light scattering reveals narrow particle size distributions in these suspensions. Smooth spherical particles with pores growing from the center to the periphery are observed by using transmission electron microscopy, suggesting a seed‐growth mechanism. The template molecules could be extracted from the nanoscale mesoporous particles via sonication in acidic media. The resulting nanoparticles give rise to type IV adsorption isotherms revealing typical mesopores and additional textural porosity. High surface areas of over 1000 m2 g–1 and large pore volumes of up to 1 mL g–1 are obtained for these extracted samples. 相似文献
4.
Y.&#x;F. Shi Y. Meng D.&#x;H. Chen S.&#x;J. Cheng P. Chen H.&#x;F. Yang Y. Wan D.&#x;Y. Zhao 《Advanced functional materials》2006,16(4):561-567
Highly ordered mesoporous silicon carbide ceramics have been successfully synthesized with yields higher than 75 % via a one‐step nanocasting process using commercial polycarbosilane (PCS) as a precursor and mesoporous silica as hard templates. Mesoporous SiC nanowires in two‐dimensional (2D) hexagonal arrays (p6m) can be easily replicated from a mesoporous silica SBA‐15 template. Small‐angle X‐ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images show that the SiC nanowires have long‐range regularity over large areas because of the interwire pillar connections. A three‐dimensional (3D) bicontinuous cubic mesoporous SiC structure (Ia3d) can be fabricated using mesoporous silica KIT‐6 as the mother template. The structure shows higher thermal stability than the 2D hexagonal mesoporous SiC, mostly because of the 3D network connections. The major constituent of the products is SiC, with 12 % excess carbon and 14 % oxygen measured by elemental analysis. The obtained mesoporous SiC ceramics are amorphous below 1200 °C and are mainly composed of randomly oriented β‐SiC crystallites after treatment at 1400 °C. N2‐sorption isotherms reveal that these ordered mesoporous SiC ceramics have high Brunauer–Emmett–Teller (BET) specific surface areas (up to 720 m2 g–1), large pore volumes (～ 0.8 cm3 g–1), and narrow pore‐size distributions (mean values of 2.0–3.7 nm), even upon calcination at temperatures as high as 1400 °C. The rough surface and high order of the nanowire arrays result from the strong interconnections of the SiC products and are the main reasons for such high surface areas. XRD, N2‐sorption, and TEM measurements show that the mesoporous SiC ceramics have ultrahigh stability even after re‐treatment at 1400 °C under a N2 atmosphere. Compared with 2D hexagonal SiC nanowire arrays, 3D cubic mesoporous SiC shows superior thermal stability, as well as higher surface areas (590 m2 g–1) and larger pore volumes (～ 0.71 cm3 g–1). 相似文献
5.
B.&#x;D. Hatton K. Landskron W. Whitnall D.&#x;D. Perovic G.&#x;A. Ozin 《Advanced functional materials》2005,15(5):823-829
Periodic mesoporous organosilica (PMO) thin films have been produced using an evaporation‐induced self‐assembly (EISA) spin‐coating procedure and a cationic surfactant template. The precursors are silsesquioxanes of the type (C2H5O)3Si–R–Si(OC2H5)3 or R′–[Si(OC2H5)3]3 with R = methene (–CH2–), ethylene (–C2H2–), ethene (–C2H4–), 1,4‐phenylene (C6H4), and R′ = 1,3,5‐phenylene (C6H3). The surfactant is successfully removed by solvent extraction or calcination without any significant Si–C bond cleavage of the organic bridging groups R and R′ within the channel walls. The materials have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X‐ray diffraction (PXRD), and 29Si and 13C magic‐angle spinning (MAS) NMR spectroscopy. The d‐spacing of the PMOs is found to be a function of R. Nanoindentation measurements reveal increased mechanical strength and stiffness for the PMOs with R = CH2 and C2H4 compared to silica. Films with different organic‐group content have been prepared using mixtures of silsesquioxane and tetramethylorthosilicate (TMOS) precursors. The dielectric constant (k) is found to decrease with organic content, and values as low as 1.8 have been measured for films thermally treated to cause a “self‐hydrophobizing” bridging‐to‐terminal transformation of the methene to methyl groups with concomitant loss of silanols. Increasing the organic content and thermal treatment also increases the resistance to moisture adsorption in 60 and 80 %‐relative‐humidity (RH) environments. Methene PMO films treated at 500 °C are found to be practically unchanged after five days exposure to 80 % RH. These low dielectric constants, plus the good thermal and mechanical stability and the hydrophobicity suggest the potential utility of these films as low‐k layers in microelectronics. 相似文献
6.
Poly(vinylbenzyl chloride), (PVBC) latex particles of about 100 nm in size are prepared by emulsion polymerization. Silyl functional groups are introduced onto the PVBC‐nanoparticle templates via surface‐initiated atom transfer radical polymerization of 3‐(trimethoxysilyl)propyl methacrylate. The silyl groups are then converted into a silica shell, approximately 20 nm thick, via a reaction with tetraethoxysilane in ethanolic ammonia. Hollow silica nanospheres are finally generated by thermal decomposition of the PVBC template cores. Field‐emission scanning electron microscopy and field‐emission transmission electron microscopy are used to characterize the intermediate products and the hollow nanospheres. Fourier‐transform infrared spectroscopy results indicate that the polymer cores are completely decomposed. 相似文献
7.
Hierarchical carbon materials with functional groups residing at the surface are prepared for the first time by using nanostructured silica materials as templates in combination with hydrothermal carbonization at mild temperatures (180 °C). Different carbon morphologies (e.g., macroporous casts, hollow spheres, carbon nanoparticles, and mesoporous microspheres) can be obtained by simply altering the polarity of the silica surface. The surface functionality and hydrophilicity of the resulting materials are assessed by Fourier transform IR spectroscopy, X‐ray photoelectron analysis, and water porosimetry. Raman spectroscopy and X‐ray diffraction measurements show that the materials are of the carbon‐black type, similar to charcoal. 相似文献
8.
W. S. Choi H. Y. Koo Z. Zhongbin Y. Li D.‐Y. Kim 《Advanced functional materials》2007,17(11):1743-1749
Porous capsules composed of hematite, silica, and hematite–silica composites are prepared by a templated synthesis method. Polyelectrolyte multilayer‐coated particles (PEMPs) are used to synthesize goethite nanocrystals and the resulting goethite‐nanocrystal‐embedded PEMPs (PEMP–goethite) are then used as templates to form porous capsules. The surface morphology and surface area of the porous capsules can be controlled by the size of the PEMP–goethite template, which is determined by the extent of growth of the goethite nanocrystals. By controlling the surface morphology and area, it is also possible to tune the sensitivity of the hematite capsules for use as gas‐sensing materials. This surfactant‐free approach is also used to synthesize silica and silica‐based composite capsules with a controllable porous shell thickness. This straightforward approach can also be extended to the synthesis of other porous capsules or particles with a controllable surface morphology. 相似文献
9.
D. Fattakhova‐Rohlfing M. Wark T. Brezesinski B. M. Smarsly J. Rathouský 《Advanced functional materials》2007,17(1):123-132
A study of electrochemical Li insertion combined with structural and textural analysis enabled the identification and quantification of individual crystalline and amorphous phases in mesoporous TiO2 films prepared by the evaporation‐induced self‐assembly procedure. It was found that the properties of the amphiphilic block copolymers used as templates, namely those of a novel poly(ethylene‐co‐butylene)‐b‐poly(ethylene oxide) polymer (KLE) and commercial Pluronic P123 (HO(CH2CH2O)20(CH2CH(CH3)O)70(CH2CH2O)20H), decisively influence the physicochemical properties of the resulting films. The KLE‐templated films possess a 3D cubic mesoporous structure and are practically amorphous when calcined at temperatures below 450 °C, but treatment at 550–700 °C provides a pure‐phase (anatase), fully crystalline material with intact mesoporous architecture. The electrochemically determined fraction of crystalline anatase increases from 85 to 100 % for films calcined at 550 and 700 °C, respectively. In contrast, the films prepared using Pluronic P123, which also show a 3D cubic pore arrangement, exhibit almost 50 % crystallinity even at a calcination temperature of 400 °C, and their transformation into a fully crystalline material is accompanied by collapse of the mesoporous texture. Therefore, our study revealed the significance of using suitable block‐copolymer templates for the generation of mesoporous metal oxide films. Coupling of both electrochemical and X‐ray diffraction methods has shown to be highly advisable for the correct interpretation of structure properties, in particular the crystallinity, of such sol–gel derived films. 相似文献
10.
K.&#x;T. Lee J.&#x;C. Lytle N.&#x;S. Ergang S.&#x;M. Oh A. Stein 《Advanced functional materials》2005,15(4):547-556
Three‐dimensionally ordered macroporous (3DOM) materials are composed of well‐interconnected pore and wall structures with wall thicknesses of a few tens of nanometers. These characteristics can be applied to enhance the rate performance of lithium‐ion secondary batteries. 3DOM monoliths of hard carbon have been synthesized via a resorcinol‐formaldehyde sol–gel process using poly(methyl methacrylate) colloidal‐crystal templates, and the rate performance of 3DOM carbon electrodes for lithium‐ion secondary batteries has been evaluated. The advantages of monolithic 3DOM carbon electrodes are: 1) solid‐state diffusion lengths for lithium ions of the order of a few tens of nanometers, 2) a large number of active sites for charge‐transfer reactions because of the material's high surface area, 3) reasonable electrical conductivity of 3DOM carbon due to a well‐interconnected wall structure, 4) high ionic conductivity of the electrolyte within the 3DOM carbon matrix, and 5) no need for a binder and/or a conducting agent. These factors lead to significantly improved rate performance compared to a similar but non‐templated carbon electrode and compared to an electrode prepared from spherical carbon with binder. To increase the energy density of 3DOM carbon, tin oxide nanoparticles have been coated on the surface of 3DOM carbon by thermal decomposition of tin sulfate, because the specific capacity of tin oxide is larger than that of carbon. The initial specific capacity of SnO2‐coated 3DOM carbon increases compared to that of 3DOM carbon, resulting in a higher energy density of the modified 3DOM carbon. However, the specific capacity decreases as cycling proceeds, apparently because lithium–tin alloy nanoparticles were detached from the carbon support by volume changes during charge–discharge processes. The rate performance of SnO2‐coated 3DOM carbon is improved compared to 3DOM carbon. 相似文献
11.
M. Yang J. Ma Z. Niu X. Dong H. Xu Z. Meng Z. Jin Y. Lu Z. Hu Z. Yang 《Advanced functional materials》2005,15(9):1523-1528
Hollow latex cages (HLCs) are used as templates to fabricate composite hollow spheres with complex structures. The template HLCs have a polystyrene shell with transverse hydrophilic channels connecting to an interior hydrophilic surface. They are stable and permeable, and a reagent can be preloaded into the cavity reservoir. The interior hydrophilic surface is conducive to a favorable inward synthesis. By simply altering the loading sequence of reagents and their concentration, the morphology of the composite spheres can be tuned. For example, during the formation of titania composite spheres by a sol–gel process using tetrabutyl titanate (TBT), composite hollow spheres with titania pillars protruding from the surface are predominantly created, owing to the formation of titania within the hydrophilic channels when the HLCs, preloaded with water, are immersed into TBT at an appropriate concentration. When the TBT concentration is decreased, the size of the pillars decreases accordingly until they disappear, leading to a smooth outer surface. Conversely, when HLCs loaded with TBT are immersed into water, titania forms only on the interior hydrophilic surface and not within the channels, resulting in composite hollow spheres with smooth outer surfaces. The composite spheres can be further used as templates to grow material on the outer surface, and double‐shelled hollow spheres of various compositions are achieved. Macroporous materials with unique morphologies—for example, hollow spheres embedded within the pores—have been derived by using an array template of the composite spheres. The method can be applied to a diversity of inorganic materials, metals, oxides, semiconductors, and functional polymers. 相似文献
12.
S.&#x;Y. Choi M. Mamak N. Coombs N. Chopra G.&#x;A. Ozin 《Advanced functional materials》2004,14(4):335-344
Herein a novel synthetic route is described for the production of thermally stable, structurally well‐defined two‐dimensional (2D) hexagonal mesoporous nanocrystalline anatase (meso‐nc‐TiO2), with a large pore diameter, narrow pore‐size distribution, high surface area, and robust inorganic walls comprised of nanocrystalline anatase. The synthetic approach involves the evaporation‐induced co‐assembly of a non‐ionic amphiphilic triblock‐copolymer template and titanium tetraethoxide, but with a pivotal change in the main solvent of the system, where the commonly used ethanol is replaced with 1‐butanol. This seemingly minor modification in solvent type from ethanol to 1‐butanol turns out to be the key synthetic strategy for achieving a robust, structurally well‐ordered meso‐nc‐TiO2 material in the form of either thick or thin films. The beneficial “solvent” effect originates from the higher hydrophobicity of 1‐butanol than ethanol, enhancing microphase separation and templating, lower critical micelle concentration of the template in 1‐butanol, and the ability to increase the relative concentration of the inorganic precursor to template in the co‐assembly synthesis. Moreover, thin films with dimensions of several centimeters that are devoid of cracks down to the length scale of the mesostructure itself, having high porosity, well‐defined mesostructural features, and semi‐crystalline pore walls were straightforwardly and reproducibly obtained as a result of the physicochemical property advantages of 1‐butanol over ethanol within our synthesis scheme. 相似文献
13.
M.&#x;B. Yue Y. Chun Y. Cao X. Dong J.&#x;H. Zhu 《Advanced functional materials》2006,16(13):1717-1722
A novel CO2 capture phenomenon is observed by modifying as‐prepared mesoporous silica SBA‐15 (SBA(P)) with tetraethylenepentamine (TEPA), not only conserving the energy and time required for removing the template, but also opening the way to utilizing the micelle for dispersing guest species. The TEPA species dispersed within the channels of SBA(P) are highly accessible to CO2 molecules; moreover, the hydroxyl group of the poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (Pluronic P123) template is able to modify the interactions between CO2 and the amine to enhance the adsorptive capacity of this system. The remarkably high adsorption capacity (173 mg g–1) of this mesoporous silica–amine composite suggests potential CO2 trapping applications, especially at low CO2 concentrations during prolonged cyclic operations. 相似文献
14.
Y.H. Wu B.J. Yang G.C. Han B.Y. Zong H.Q. Ni P. Luo T.C. Chong T.S. Low Z.X. Shen 《Advanced functional materials》2002,12(8):489-494
Well‐aligned carbon nanowalls with a thickness of a few nanometers and a lateral size in the micrometer range have been grown on various types of substrates. The nanowalls exhibit a remarkably different surface morphology as compared to fullerenes and carbon nanotubes, in particular their two‐dimensionality and high surface area. In this work, we focused on the second aspect and developed a templating method to fabricate a class of nanostructured materials based on the novel surface morphology of the carbon nanowalls. These structures may have potential applications in batteries, gas sensors, catalysts, and light‐emission/detection, field‐emission, and biomedical devices. 相似文献
15.
P.&#x;V. Braun P. Osenar M. Twardowski G.&#x;N. Tew S.&#x;I. Stupp 《Advanced functional materials》2005,15(11):1745-1750
Aqueous gel‐like lyotropic liquid crystals with extensive hydrogen bonding and nanoscale hydrophilic compartments have been used to define the growth of macroscopic nanotemplated CdS and CdTe thin films. These mesoporous semiconductor films contain a hexagonal array of 2.5 nm pores, 7 nm center‐to‐center, that extend in an aligned fashion perpendicular to the substrate. The CdS is deposited on a polypropylene substrate by a reaction between Cd(NO3)2 dissolved in the liquid crystal and H2S transported via diffusion through the substrate. The CdTe is electrodeposited on indium‐tin‐oxide‐coated glass from TeO2 and Cd(NO3)2, both of which are dissolved in the liquid‐crystal template. The porous nature of the CdTe films enables chemical transformations of the entire bulk of the film. As electrodeposited, the CdTe films are Te rich and, in contrast to a non‐templated film, the excess Te could be removed via a chemical treatment, proving the continuity of the pores in the nanotemplated films. These results suggest that liquid‐crystal lithography with hydrogen‐bonding amphiphiles may be a useful approach to create materials with nanoscale features over macroscopic dimensions. 相似文献
16.
Liquid crystalline epoxy/polyaniline (LCE/PANI) composite nanowires have been fabricated using an anodic aluminum oxide (AAO) membrane by a temperature‐gradient curing process. PANI nanorods with an average diameter of 30 nm have been synthesized by dispersion polymerization in order to employ them as a curing agent for LCE and as a reinforcement filler for the LCE/PANI composite nanowires. Differential scanning calorimetry and Fourier‐transform infrared spectroscopy indicate that the LCE crosslinking reaction occurred inside the channels of the AAO membrane via the curing of LCE with PANI nanorods. The LCE/PANI composite nanowires exhibit an enhanced electrical conductivity and thermal stability, comparable with a LCE/PANI composite monolith. In addition, these polymer‐composite nanowires also display the characteristics of a functionally gradient conducting material. 相似文献
17.
A.&#x;S. Deshpande D.&#x;G. Shchukin E. Ustinovich M. Antonietti R.&#x;A. Caruso 《Advanced functional materials》2005,15(2):239-245
Porous polymer beads have been used as templates in which sol–gel chemistry was conducted for the formation of porous titanium dioxide and titania/aluminum, gallium, or indium oxide spheres. The addition of 5, 10, and 15 wt.‐% of the second metal oxide to titania was studied, resulting in little variation in the final porous‐sphere diameter, but in a decreased titania nanocrystal size and an increased specific surface area of the material. The crystallinity of the samples was observed after heating at 550, 750, and 950 °C as anatase to rutile phase transitions became apparent and peaks from the added metal oxide were observed with the increase in temperature. Photocatalytic decomposition of 2‐chlorophenol was monitored in the presence of the titania and titania/metal‐oxide spheres showing that a 5 wt.‐% addition of the second metal oxide gave best photocatalytic results for all the metal oxides studied. At a pH of 6 the pure titania spheres were less photocatalytically active than the Degussa P25 titania, however the mixed titania/5 wt.‐% metal‐oxide samples were more active than the standard in the order In (least active), Ga, then Al (most active). Variation of the solution pH (between pH 2 and 10) had little influence on the photocatalytic activity of the titania/5 wt.‐% aluminum oxide material, more effect on the titanium/5 wt. % gallium oxide, and the most pronounced effect on the titanium/5 wt.‐% indium oxide, with increased activity at higher pH values. The adsorption of pyridine to the titania samples containing the second metal oxide indicated the presence of Lewis‐acid sites. 相似文献
18.
Direct glucose sensing on highly ordered platinum‐nanotubule array electrodes (NTAEs) is systematically investigated. The NTAEs are fabricated by electrochemical deposition of platinum in a 3‐aminopropyltrimethoxysilane‐modified anodic alumina membrane. Their structures and morphologies are then characterized using X‐ray diffraction and scanning electron microscopy, respectively. Electrochemical results show that NTAEs with different real surface areas could be achieved by controlling the deposition time or by using anodic alumina membranes with different pore size. Electrochemical responses of the as‐synthesized NTAEs to glucose in a solutions of either 0.5 M H2SO4, or phosphate‐buffered saline (PBS, pH 7.4) containing 0.1 M KCl are discussed. Based on the different electrochemical reaction mechanisms of glucose and interferents such as p‐acetamedophenol and ascorbic acid, their high roughness factor makes NTAEs sensitive, selective, and stable enough to be a kind of biosensor for the non‐enzymatic detection of glucose. Such a glucose sensor allows the determination of glucose in the linear range 2–14 mM, with a sensitivity of 0.1 μA cm–2 mM–1 (correlation coefficient 0.999), and a detection limit of 1.0 μM glucose, with neglectable interference from physiological levels of 0.1 mM p‐acetamedophenol, 0.1 mM ascorbic acid, and 0.02 mM uric acid. 相似文献
19.
A mesocellular silica–carbon nanocomposite foam (MSCF) is designed for the immobilization and biosensing of proteins. The as‐prepared MSCF has a highly ordered mesostructure, good biocompatibility, favorable conductivity and hydrophilicity, large surface area, and a narrow pore‐size distribution, as verified by transmission electron microscopy (TEM), IR spectroscopy, electrochemical impedance spectroscopy (EIS), nitrogen adsorption–desorption isotherms, pore size distribution plots, and water contact angle measurements. Using glucose oxidase (GOD) as a model, the MSCF is tested for immobilization of redox proteins and the design of electrochemical biosensors. GOD molecules immobilized in the mesopores of the MSCF show direct electrochemistry with a fast electron transfer rate (14.0 ± 1.7 s–1) and good electrochemical performance. Based on a decrease of the electrocatalytic response of the reduced form of GOD to dissolved oxygen, the proposed biosensor exhibits a linear response to glucose concentrations ranging from 50 μM to 5.0 mM with a detection limit of 34 μM at an applied potential of –0.4 V. The biosensor shows good stability and selectivity and is able to exclude interference from ascorbic acid (AA) and uric acid (UA) species that always coexist with glucose in real samples. The nanocomposite foam provides a good matrix for protein immobilization and biosensor preparation. 相似文献
20.
A new concept is proposed to synthesize mesoporous magnetic nanocomposite particles of great scientific and technological importance. Mesoporous silica coatings were created on micrometer‐sized magnetite (Fe3O4) particles using cetyltrimethylammonium chloride micelles as molecular templates. The characterization by transmission electron microscopy (TEM), nitrogen adsorption–desorption, diffuse‐reflectance Fourier‐transform infrared spectroscopy, and zeta‐potential measurements confirmed the deposition of mesoporous silica thin layers on the magnetite particles. The synthesized particles showed a drastic increase in specific surface area with an average pore size of 2.5 nm. The coating material showed a negligible effect on the saturation magnetization of the original particles that were fully protected by silica coatings. The synthesized mesoporous magnetic nanocomposite particles have a wide range of applications in toxin removal, waste remediation, catalysis, reactive sorbents, and biological cell separations. 相似文献