Solar hydrogen and solar electricity using mesoporous materials

NASA Astrophysics Data System (ADS)

Mahoney, Luther

The development of cost-effective materials for effective utilization of solar energy is a major challenge for solving the energy problems that face the world. This thesis work relates to the development of mesoporous materials for solar energy applications in the areas of photocatalytic water splitting and the generation of electricity. Mesoporous materials were employed throughout the studies because of their favorable physico-chemical properties such as high surface areas and large porosities. The first project was related to the use of a cubic periodic mesoporous material, MCM-48. The studies showed that chromium loading directly affected the phase of mesoporous silica formed. Furthermore, within the cubic MCM-48 structure, the loading of polychromate species determined the concentration of solar hydrogen produced. In an effort to determine the potential of mesoporous materials, titanium dioxide was prepared using the Evaporation-Induced Self-Assembly (EISA) synthetic method. The aging period directly determined the amount of various phases of titanium dioxide. This method was extended for the preparation of cobalt doped titanium dioxide for solar simulated hydrogen evolution. In another study, metal doped systems were synthesized using the EISA procedure and rhodamine B (RhB) dye sensitized and metal doped titania mesoporous materials were evaluated for visible light hydrogen evolution. The final study employed various mesoporous titanium dioxide materials for N719 dye sensitized solar cell (DSSC) materials for photovoltaic applications. The materials were extensively characterized using powder X-ray diffraction (XRD), nitrogen physisorption, diffuse reflectance spectroscopy (DRS), UV-Vis spectroscopy, Fourier-Transform-Infrared Spectroscopy (FT-IR), Raman spectroscopy, chemisorption, photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). In addition, photoelectrochemical measurements were completed using current-voltage (I-V) curves, external quantum efficiency (EQE) curves, electrochemical impedance spectroscopy (EIS), and transient spectroscopy. The thesis work presented provides a better understanding of the role of mesoporous materials for solar hydrogen and solar electricity production.

Functionalized mesoporous materials for adsorption and release of different drug molecules: A comparative study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Gang; Otuonye, Amy N.; Blair, Elizabeth A.

2009-07-15

The adsorption capacity and release properties of mesoporous materials for drug molecules can be improved by functionalizing their surfaces with judiciously chosen organic groups. Functionalized ordered mesoporous materials containing various types of organic groups via a co-condensation synthetic method from 15% organosilane and by post-grafting organosilanes onto a pre-made mesoporous silica were synthesized. Comparative studies of their adsorption and release properties for various model drug molecules were then conducted. Functional groups including 3-aminopropyl, 3-mercaptopropyl, vinyl, and secondary amine groups were used to functionalize the mesoporous materials while rhodamine 6G and ibuprofen were utilized to investigate the materials' relative adsorption andmore » release properties. The self-assembly of the mesoporous materials was carried out in the presence of cetyltrimethylammonium bromide (CTAB) surfactant, which produced MCM-41 type materials with pore diameters of {approx}2.7-3.3 nm and moderate to high surface areas up to {approx}1000 m{sup 2}/g. The different functional groups introduced into the materials dictated their adsorption capacity and release properties. While mercaptopropyl and vinyl functionalized samples showed high adsorption capacity for rhodamine 6G, amine functionalized samples exhibited higher adsorption capacity for ibuprofen. While the diffusional release of ibuprofen was fitted on the Fickian diffusion model, the release of rhodamine 6G followed Super Case-II transport model. - Graphical abstract: The adsorption capacity and release properties of mesoporous materials for various drug molecules are tuned by functionalizing the surfaces of the materials with judiciously chosen organic groups. This work reports comparative studies of the adsorption and release properties of functionalized ordered mesoporous materials containing different hydrophobic and hydrophilic groups that are synthesized via a co-condensation and post-grafting methods for various model drug molecules.« less

Mesoporous metal oxide graphene nanocomposite materials

DOEpatents

Liu, Jun; Aksay, Ilhan A.; Kou, Rong; Wang, Donghai

2016-05-24

A nanocomposite material formed of graphene and a mesoporous metal oxide having a demonstrated specific capacity of more than 200 F/g with particular utility when employed in supercapacitor applications. A method for making these nanocomposite materials by first forming a mixture of graphene, a surfactant, and a metal oxide precursor, precipitating the metal oxide precursor with the surfactant from the mixture to form a mesoporous metal oxide. The mesoporous metal oxide is then deposited onto a surface of the graphene.

Organic-inorganic hybrid mesoporous silicas: functionalization, pore size, and morphology control.

PubMed

Park, Sung Soo; Ha, Chang-Sik

2006-01-01

Topological design of mesoporous silica materials, pore architecture, pore size, and morphology are currently major issues in areas such as catalytic conversion of bulky molecules, adsorption, host-guest chemistry, etc. In this sense, we discuss the pore size-controlled mesostructure, framework functionalization, and morphology control of organic-inorganic hybrid mesoporous silicas by which we can improve the applicability of mesoporous materials. First, we explain that the sizes of hexagonal- and cubic-type pores in organic-inorganic hybrid mesoporous silicas are well controlled from 24.3 to 98.0 A by the direct micelle-control method using an organosilica precursor and surfactants with different alkyl chain lengths or triblock copolymers as templates and swelling agents incorporated in the formed micelles. Second, we describe that organic-inorganic hybrid mesoporous materials with various functional groups form various external morphologies such as rod, cauliflower, film, rope, spheroid, monolith, and fiber shapes. Third, we discuss that transition metals (Ti and Ru) and rare-earth ions (Eu(3+) and Tb(3+)) are used to modify organic-inorganic hybrid mesoporous silica materials. Such hybrid mesoporous silica materials are expected to be applied as excellent catalysts for organic reactions, photocatalysis, optical devices, etc. c) 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Small-angle X-ray scattering (SAXS) studies of the structure of mesoporous silicas

NASA Astrophysics Data System (ADS)

Zienkiewicz-Strzałka, M.; Skibińska, M.; Pikus, S.

2017-11-01

Mesoporous ordered silica nanostructures show strong interaction with X-ray radiation in the range of small-angles. Small-angle X-ray scattering (SAXS) measurements based on the elastically scattered X-rays are important in analysis of condensed matter. In the case of mesoporous silica materials SAXS technique provides information on the distribution of electron density in the mesoporous material, in particular describing their structure and size of the unit cell as well as type of ordered structure and finally their parameters. The characterization of nanopowder materials, nanocomposites and porous materials by Small-Angle X-ray Scattering seems to be valuable and useful. In presented work, the SAXS investigation of structures from the group of mesoporous ordered silicates was performed. This work has an objective to prepare functional materials modified by noble metal ions and nanoparticles and using the small-angle X-ray scattering to illustrate their properties. We report the new procedure for describing mesoporous materials belonging to SBA-15 and MCM-41 family modified by platinum, palladium and silver nanoparticles, based on detailed analysis of characteristic peaks in the small-angle range of X-ray scattering. This procedure allows to obtained the most useful parameters for mesoporous materials characterization and their successfully compare with experimental measurements reducing the time and material consumption with good precision for particles and pores with a size below 10 nm.

Surface functionalized mesoporous material and method of making same

DOEpatents

Feng, Xiangdong [West Richland, WA; Liu, Jun [West Richland, WA; Fryxell, Glen E [Kennewick, WA

2001-12-04

According to the present invention, an organized assembly of functional molecules with specific interfacial functionality (functional group(s)) is attached to available surfaces including within mesopores of a mesoporous material. The method of the present invention avoids the standard base soak that would digest the walls between the mesopores by boiling the mesoporous material in water for surface preparation then removing all but one or two layers of water molecules on the internal surface of a pore. Suitable functional molecule precursor is then applied to permeate the hydrated pores and the precursor then undergoes condensation to form the functional molecules on the interior surface(s) of the pore(s).

Environmental and Biomedical Applications of Iron Oxide/Mesoporous Silica Core-Shell Nanocomposites

NASA Astrophysics Data System (ADS)

Egodawatte, Shani Nirasha

Mesoporous silica has shown great potential as an adsorbent for environmental contaminants and as a host for imaging and therapeutic agents. Mesoporous silica materials have a high surface area, tunable pore sizes and well defined surface properties which are governed by the surface hydroxyl groups. Surface modification of the mesoporous silica can tailor the adsorption properties for a specific metal ion or a small drug molecule by providing better sites for chelation or electrostatic interactions. Iron oxide / mesoporous silica core shell materials couple the favorable properties of both the iron oxide and mesoporous silica materials. The core-shell materials have higher adsorption properties compared to the parent material. With magnetic iron oxide nanoparticle cores, an additional magnetic property is introduced that can be used as magnetic recovery or separation. Heavy metals such as Chromium (Cr) and Arsenic (As) discharged from residential and environmental sources pose a serious threat to human health as well as groundwater pollution. In this thesis, iron oxide nanoparticles and nanofibers were coated with mesoporous silica and functionalized with (3-aminopropyl)triethoxysilane (APTES) using the post synthesis grafting method. The parent and the functionalized magnetic silica samples were characterized using powder X-ray diffraction (pXRD), thermal gravimetric analysis (TGA), Fourier Transform Infrared (FTIR) spectroscopy and nitrogen adsorption desorption isotherms for surface area and pore volumes. These materials were evaluated for Cr(III) and As(III)/As(V) adsorption from aqueous solutions in the optimum pH range for the specific metal. The aminopropyl functionalized magnetic mesoporous silica displayed the highest adsorption capacity for Cr(III) and Cu(II) of all the materials evaluated in this study. The high heavy metal adsorption capacity was attributed to a synergistic effect of iron oxide nanoparticles and amine functionalization on mesoporous silica as well as a judicious choice of pH. Modified magnetic mesoporous silica material was also found to have high adsorption capacity for high and low pH aqueous solutions of Uranium (VI). Tuning the loading and release of a small drug molecule (5-FU) onto these iron oxide/ mesoporous silica core-shell materials was also investigated. The polarity of the solvent used to load 5-FU onto the host had an impact not only on the loading but also on the release percentage of 5-FU. The synthesis of a novel core-shell material with a hematite nanofiber core and a SBA type mesoporous silica shell was also explored.

Tubular structured hierarchical mesoporous titania material derived from natural cellulosic substances and application as photocatalyst for degradation of methylene blue

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Haiqing; Liu, Xiaoyan; Huang, Jianguo, E-mail: jghuang@zju.edu.cn

Graphical abstract: Bio-inspired, tubular structured hierarchical mesoporous titania material with high photocatalytic activity under UV light was fabricated employing natural cellulosic substance (cotton) as hard template and cetyltrimethylammonium bromide (CTAB) surfactant as soft template using a one-pot sol-gel method. Highlights: {yields} Tubular structured mesoporous titania material was fabricated by sol-gel method. {yields} The titania material faithfully recorded the hierarchical structure of the template substrate (cotton). {yields} The titania material exhibited high photocatalytic activity in decomposition of methylene blue. -- Abstract: Bio-inspired, tubular structured hierarchical mesoporous titania material was designed and fabricated employing natural cellulosic substance (cotton) as hard template andmore » cetyltrimethylammonium bromide (CTAB) surfactant as soft template by one-pot sol-gel method. The tubular structured hierarchical mesoporous titania material processes large specific surface area (40.23 m{sup 2}/g) and shows high photocatalytic activity in the photodegradation of methylene blue under UV light irradiation.« less

Synthesis and electrochemical performance of mesoporous SiO{sub 2}–carbon nanofibers composite as anode materials for lithium secondary batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hyun, Yura; Choi, Jin-Yeong; Park, Heai-Ku

Highlights: • Mesoporous SiO{sub 2}–carbon nanofibers composite synthesized on Ni foam without any binder. • This composite was directly applied as anode material of Li secondary batteries. • Showed the highest initial (2420 mAh/g) and discharging (2092 mAh/g) capacity. • This material achieved a retention rate of 86.4% after 30 cycles. - Abstract: In this study, carbon nanofibers (CNFs) and mesoporous SiO{sub 2}–carbon nanofibers composite were synthesized and applied as the anode materials in lithium secondary batteries. CNFs and mesoporous SiO{sub 2}–CNFs composite were grown via chemical vapor deposition method with iron-copper catalysts. Mesoporous SiO{sub 2} materials were prepared bymore » sol–gel method using tetraethylorthosilicate as the silica source and cetyltrimethylammoniumchloride as the template. Ethylene was used as the carbon source and passes into a quartz reactor of a tube furnace heated to 600 °C, and the temperature was maintained at 600 °C for 10 min to synthesize CNFs and mesoporous SiO{sub 2}–CNFs composite. The electrochemical characteristics of the as-prepared CNFs and mesoporous SiO{sub 2}–CNFs composite as the anode of lithium secondary batteries were investigated using a three-electrode cell. In particular, the mesoporous SiO{sub 2}–CNFs composites synthesized without binder after depositing mesoporous SiO{sub 2} on Ni foam showed the highest charging and discharging capacity and retention rate. The initial capacity (2420 mAh/g) of mesoporous SiO{sub 2}–CNFs composites decreased to 2092 mAh/g after 30 cycles at a retention rate of 86.4%.« less

A Review of Recent Developments of Mesoporous Materials.

PubMed

Suib, Steven L

2017-12-01

This personal account concerns novel recent discoveries in the area of mesoporous materials. Most of the papers discussed have been published within the last two to three years. A major emphasis of most of these papers is the synthesis of unique mesoporous materials by a variety of synthetic methods. Many of these articles focus on the control of the pore sizes and shapes of mesoporous materials. Synthetic methods of various types have been used for such control of porosity including soft templating, hard templating, nano-casting, electrochemical methods, surface functionalization, and trapping of species in pores. The types of mesoporous materials range from carbon materials, metal oxides, metal sulfides, metal nitrides, carbonitriles, metal organic frameworks (MOFs), and composite materials. The vast majority of recent publications have centered around biological applications with a majority dealing with drug delivery systems. Several other bio-based articles on mesoporous systems concern biomass conversion and biofuels, magnetic resonance imaging (MRI) studies, ultrasound therapy, enzyme immobilization, antigen targeting, biodegradation of inorganic materials, applications for improved digestion, and antitumor activity. Numerous nonbiological applications of mesoporous materials have been pursued recently. Some specific examples are photocatalysis, photo-electrocatalysis, lithium ion batteries, heterogeneous catalysis, extraction of metals, extraction of lanthanide and actinide species, chiral separations and catalysis, capturing and the mode of binding of carbon dioxide (CO 2 ), optical devices, and magneto-optical devices. Of this latter class of applications, heterogeneous catalysis is predominant. Some of the types of catalytic reactions being pursued include hydrogen generation, selective oxidations, aminolysis, Suzuki coupling and other coupling reactions, oxygen reduction reactions (ORR), oxygen evolution reactions (OER), and bifunctional catalysis. For perspective, there have been over 40,000 articles on mesoporous materials published in the last 4 years and about 1388 reviews. By no means is this personal account thorough or all inclusive. One objective has been to choose a variety of articles of different types to obtain a flavor of the breadth of diversity involved in the area of mesoporous materials. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mesoporous carbon materials

DOEpatents

Dai, Sheng [Knoxville, TN; Wang, Xiqing [Oak Ridge, TN

2012-02-14

The invention is directed to a method for fabricating a mesoporous carbon material, the method comprising subjecting a precursor composition to a curing step followed by a carbonization step, the precursor composition comprising: (i) a templating component comprised of a block copolymer, (ii) a phenolic compound or material, (iii) a crosslinkable aldehyde component, and (iv) at least 0.5 M concentration of a strong acid having a pKa of or less than -2, wherein said carbonization step comprises heating the precursor composition at a carbonizing temperature for sufficient time to convert the precursor composition to a mesoporous carbon material. The invention is also directed to a mesoporous carbon material having an improved thermal stability, preferably produced according to the above method.

Mesoporous carbon materials

DOEpatents

Dai, Sheng; Wang, Xiqing

2013-08-20

The invention is directed to a method for fabricating a mesoporous carbon material, the method comprising subjecting a precursor composition to a curing step followed by a carbonization step, the precursor composition comprising: (i) a templating component comprised of a block copolymer, (ii) a phenolic compound or material, (iii) a crosslinkable aldehyde component, and (iv) at least 0.5 M concentration of a strong acid having a pKa of or less than -2, wherein said carbonization step comprises heating the precursor composition at a carbonizing temperature for sufficient time to convert the precursor composition to a mesoporous carbon material. The invention is also directed to a mesoporous carbon material having an improved thermal stability, preferably produced according to the above method.

Ordered mesoporous ternary mixed oxide materials as potential adsorbent of biomolecules

NASA Astrophysics Data System (ADS)

Pal, Nabanita; Bhaumik, Asim

2012-05-01

Designing a suitable mesoporous framework material for the selective adsorption or immobilization of biomolecules is a very challenging area of research. Mesoporous ternary Co-Si-Al oxide materials with large mesopore and their nanoscale ordering have been reported. The synthesis of these ternary oxides are accomplished through evaporation induced self-assembly (EISA) method using Pluronic non-ionic surfactant F127 under non-aqueous sol-gel route. N2 sorption study revealed high BET surface areas for these materials. These materials exhibited very efficient and selective adsorption for the essential biomolecules like vitamin C (ascorbic acid), vitamin B6 (pyridoxine) and vitamin B3 (nicotinic acid) from their respective aqueous solutions.

Hierarchically ordered mesoporous Co3O4 materials for high performance Li-ion batteries.

PubMed

Sun, Shijiao; Zhao, Xiangyu; Yang, Meng; Wu, Linlin; Wen, Zhaoyin; Shen, Xiaodong

2016-01-19

Highly ordered mesoporous Co3O4 materials have been prepared via a nanocasting route with three-dimensional KIT-6 and two-dimensional SBA-15 ordered mesoporous silicas as templates and Co(NO3)2 · 6H2O as precursor. Through changing the hydrothermal treating temperature of the silica template, ordered mesoporous Co3O4 materials with hierarchical structures have been developed. The larger pores around 10 nm provide an efficient transport for Li ions, while the smaller pores between 3-5 nm offer large electrochemically active areas. Electrochemical impedance analysis proves that the hierarchical structure contributes to a lower charge transfer resistance in the mesoporous Co3O4 electrode than the mono-sized structure. High reversible capacities around 1141 mAh g(-1) of the hierarchically mesoporous Co3O4 materials are obtained, implying their potential applications for high performance Li-ion batteries.

Magnetic mesoporous material for the sequestration of algae

DOEpatents

Trewyn, Brian G.; Kandel, Kapil; Slowing, Igor Ivan; Lee, Show-Ling

2014-09-09

The present invention provides a magnetic mesoporous nanoparticle that includes a mesoporous silicate nanoparticle and iron oxide. The present invention also provides a method of using magnetic mesoporous nanoparticles to sequester microorganisms from a media.

Porous silica nanoparticles as carrier for curcumin delivery

NASA Astrophysics Data System (ADS)

Hartono, Sandy Budi; Hadisoewignyo, Lannie; Irawaty, Wenny; Trisna, Luciana; Wijaya, Robby

2018-04-01

Mesoporous silica nanoparticles (MSN) with large surface areas and pore volumes show great potential as drug and gene carriers. However, there are still some challenging issues hinders their clinical application. Many types of research in the use of mesoporous silica material for drug and gene delivery involving complex and rigorous procedures. A facile and reproducible procedure to prepare combined drug carrier is required. We investigated the effect of physiochemical parameters of mesoporous silica, including structural symmetry (cubic and hexagonal), particles size (micro size: 1-2 µm and nano size: 100 -300 nm), on the solubility and release profile of curcumin. Transmission Electron Microscopy, X-Ray Powder Diffraction, and Nitrogen sorption were used to confirm the synthesis of the mesoporous silica materials. Mesoporous silica materials with different mesostructures and size have been synthesized successfully. Curcumin has anti-oxidant, anti-inflammation and anti-virus properties which are beneficial to fight various diseases such as diabetic, cancer, allergic, arthritis and Alzheimer. Curcumin has low solubility which minimizes its therapeutic effect. The use of nanoporous material to carry and release the loaded molecules is expected to enhance curcumin solubility. Mesoporous silica materials with a cubic mesostructure had a higher release profile and curcumin solubility, while mesoporous silica materials with a particle size in the range of nano meter (100-300) nm also show better release profile and solubility.

Steam-assisted crystallization of TPA{sup +}-exchanged MCM-41 type mesoporous materials with thick pore walls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Hong Li; Zhang, Kun; Wang, Yi Meng, E-mail: ymwang@chem.ecnu.edu.cn

2012-07-15

Highlights: ► Mesoporous Ti-containing silica with thicker pore walls was synthesized. ► Ion-exchange and steam-assisted crystallization led to MCM-41/MFI composite. ► The introduction of Ti inhibited the formation of separated MFI particles. ► Lower temperature favored retaining mesoporous characteristics and morphology. -- Abstract: Hierarchical MCM-41/MFI composites were synthesized through ion-exchange of as-made MCM-41 type mesoporous materials with tetrapropylammonium bromide and subsequent steam-assisted recrystallization. The obtained samples were characterized by powder X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis, FT-IR, {sup 1}H–{sup 13}C CP/MAS and nitrogen adsorption–desorption. The XRD patterns show thatmore » the MCM-41/MFI composite possesses both ordered MCM-41 phase and zeolite MFI phase. SEM and TEM images indicate that the recrystallized materials retained the mesoporous characteristics and the morphology of as-made mesoporous materials without the formation of bulky zeolite, quite different from the mechanical mixture of MCM-41 and MFI structured zeolite. Among others, lower recrystallization temperature and the introduction of the titanium to the parent materials are beneficial to preserve the mesoporous structure during the recrystallization process.« less

Micelle-Template Synthesis of Nitrogen-Doped Mesoporous Graphene as an Efficient Metal-Free Electrocatalyst for Hydrogen Production

NASA Astrophysics Data System (ADS)

Huang, Xiaodan; Zhao, Yufei; Ao, Zhimin; Wang, Guoxiu

2014-12-01

Synthesis of mesoporous graphene materials by soft-template methods remains a great challenge, owing to the poor self-assembly capability of precursors and the severe agglomeration of graphene nanosheets. Herein, a micelle-template strategy to prepare porous graphene materials with controllable mesopores, high specific surface areas and large pore volumes is reported. By fine-tuning the synthesis parameters, the pore sizes of mesoporous graphene can be rationally controlled. Nitrogen heteroatom doping is found to remarkably render electrocatalytic properties towards hydrogen evolution reactions as a highly efficient metal-free catalyst. The synthesis strategy and the demonstration of highly efficient catalytic effect provide benchmarks for preparing well-defined mesoporous graphene materials for energy production applications.

Micelle-template synthesis of nitrogen-doped mesoporous graphene as an efficient metal-free electrocatalyst for hydrogen production.

PubMed

Huang, Xiaodan; Zhao, Yufei; Ao, Zhimin; Wang, Guoxiu

2014-12-19

Synthesis of mesoporous graphene materials by soft-template methods remains a great challenge, owing to the poor self-assembly capability of precursors and the severe agglomeration of graphene nanosheets. Herein, a micelle-template strategy to prepare porous graphene materials with controllable mesopores, high specific surface areas and large pore volumes is reported. By fine-tuning the synthesis parameters, the pore sizes of mesoporous graphene can be rationally controlled. Nitrogen heteroatom doping is found to remarkably render electrocatalytic properties towards hydrogen evolution reactions as a highly efficient metal-free catalyst. The synthesis strategy and the demonstration of highly efficient catalytic effect provide benchmarks for preparing well-defined mesoporous graphene materials for energy production applications.

Micelle-Template Synthesis of Nitrogen-Doped Mesoporous Graphene as an Efficient Metal-Free Electrocatalyst for Hydrogen Production

PubMed Central

Huang, Xiaodan; Zhao, Yufei; Ao, Zhimin; Wang, Guoxiu

2014-01-01

Synthesis of mesoporous graphene materials by soft-template methods remains a great challenge, owing to the poor self-assembly capability of precursors and the severe agglomeration of graphene nanosheets. Herein, a micelle-template strategy to prepare porous graphene materials with controllable mesopores, high specific surface areas and large pore volumes is reported. By fine-tuning the synthesis parameters, the pore sizes of mesoporous graphene can be rationally controlled. Nitrogen heteroatom doping is found to remarkably render electrocatalytic properties towards hydrogen evolution reactions as a highly efficient metal-free catalyst. The synthesis strategy and the demonstration of highly efficient catalytic effect provide benchmarks for preparing well-defined mesoporous graphene materials for energy production applications. PMID:25523276

Surface-functionalized mesoporous carbon materials

DOEpatents

Dai, Sheng; Gorka, Joanna; Mayes, Richard T.

2016-02-02

A functionalized mesoporous carbon composition comprising a mesoporous carbon scaffold having mesopores in which polyvinyl polymer grafts are covalently attached, wherein said mesopores have a size of at least 2 nm and up to 50 nm. Also described is a method for producing the functionalized mesoporous composition, wherein a reaction medium comprising a precursor mesoporous carbon, vinyl monomer, initiator, and solvent is subjected to sonication of sufficient power to result in grafting and polymerization of the vinyl monomer into mesopores of the precursor mesoporous carbon. Also described are methods for using the functionalized mesoporous carbon, particularly in extracting metal ions from metal-containing solutions.

Ordered mesoporous crystalline gamma-Al2O3 with variable architecture and porosity from a single hard template.

PubMed

Wu, Zhangxiong; Li, Qiang; Feng, Dan; Webley, Paul A; Zhao, Dongyuan

2010-09-01

In this paper, an efficient route is developed for controllable synthesis of ordered mesoporous alumina (OMA) materials with variable pore architectures and high mesoporosity, as well as crystalline framework. The route is based on the nanocasting pathway with bimodal mesoporous carbon as the hard template. In contrast to conventional reports, we first realize the possibility of creating two ordered mesopore architectures by using a single carbon hard template obtained from organic-organic self-assembly, which is also the first time such carbon materials are adopted to replicate ordered mesoporous materials. The mesopore architecture and surface property of the carbon template are rationally designed in order to obtain ordered alumina mesostructures. We found that the key factors rely on the unique bimodal mesopore architecture and surface functionalization of the carbon hard template. Namely, the bimodal mesopores (2.3 and 5.9 nm) and the surface functionalities make it possible to selectively load alumina into the small mesopores dominantly and/or with a layer of alumina coated on the inner surface of the large primary mesopores with different thicknesses until full loading is achieved. Thus, OMA materials with variable pore architectures (similar and reverse mesostructures relative to the carbon template) and controllable mesoporosity in a wide range are achieved. Meanwhile, in situ ammonia hydrolysis for conversion of the metal precursor to its hydroxide is helpful for easy crystallization (as low as approximately 500 degrees C). Well-crystallized alumina frameworks composed of gamma-Al(2)O(3) nanocrystals with sizes of 6-7 nm are obtained after burning out the carbon template at 600 degrees C, which is advantageous over soft-templated aluminas. The effects of synthesis factors are demonstrated and discussed relative to control experiments. Furthermore, our method is versatile enough to be used for general synthesis of other important but difficult-to-synthesize mesoporous metal oxides, such as magnesium oxide. We believe that the fundamentals in this research will provide new insights for rational synthesis of ordered mesoporous materials.

In Situ Growth of Mesoporous Silica with Drugs on Titanium Surface and Its Biomedical Applications.

PubMed

Wan, Mimi; Zhang, Jin; Wang, Qi; Zhan, Shuyue; Chen, Xudong; Mao, Chun; Liu, Yuhong; Shen, Jian

2017-06-07

Mesoporous silica has been developed for the modification of titanium surfaces that are used as implant materials. Yet, the traditional modification methods failed to effectively construct mesoporous silica on the titanium surface evenly and firmly, in which the interaction between mesoporous silica and titanium was mainly physical. Here, in situ growth of mesoporous silica on a titanium surface was performed using a simple evaporation-induced self-assembly strategy. Meantime, in situ introduction of drugs (heparin and vancomycin) to mesoporous silica was also adopted to improve the drug-loading amount. Both the above-mentioned processes were completed at the same time. Transmission electron microscopy, N 2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy, scanning electron microscopy, and water contact angle measurements were used to characterize the structure of the mesoporous silica film. Results indicated that the mesoporous silica film that in situ grew on the titanium surface was smooth, thin, transparent, and stable. Cytotoxicity, proliferation performance of osteoblast cells, and in vitro and in vivo studies of the antibacterial activity of the coating were tested. This is the first study to modify the titanium surface by the in situ growth of a mesoporous silica coating with two kinds of drugs. The stability of the mesoporous silica coating can be attributed to the chemical bonding between dopamine and silicon hydroxyl of the mesoporous silica coating, and the smooth surface of mesoporous silica is a result of the method of in situ growth. The large amount of drug-loading also could be ascribed to the in situ introduction of drugs during the synthetic process. The strategy proposed in this work will bring more possibilities for the preparation of advanced functional materials based on the combination of mesoporous structure and metallic materials.

Mesoporous Prussian blue analogues: template-free synthesis and sodium-ion battery applications.

PubMed

Yue, Yanfeng; Binder, Andrew J; Guo, Bingkun; Zhang, Zhiyong; Qiao, Zhen-An; Tian, Chengcheng; Dai, Sheng

2014-03-17

The synthesis of mesoporous Prussian blue analogues through a template-free methodology and the application of these mesoporous materials as high-performance cathode materials in sodium-ion batteries is presented. Crystalline mesostructures were produced through a synergistically coupled nanocrystal formation and aggregation mechanism. As cathodes for sodium-ion batteries, the Prussian blue analogues all show a reversible capacity of 65 mA h g-1 at low current rate and show excellent cycle stability. The reported method stands as an environmentally friendly and low-cost alternative to hard or soft templating for the fabrication of mesoporous materials.

Mesoporous Germanium Anode Materials for Lithium-Ion Battery with Exceptional Cycling Stability in Wide Temperature Range.

PubMed

Choi, Sinho; Cho, Yoon-Gyo; Kim, Jieun; Choi, Nam-Soon; Song, Hyun-Kon; Wang, Guoxiu; Park, Soojin

2017-04-01

Porous structured materials have unique architectures and are promising for lithium-ion batteries to enhance performances. In particular, mesoporous materials have many advantages including a high surface area and large void spaces which can increase reactivity and accessibility of lithium ions. This study reports a synthesis of newly developed mesoporous germanium (Ge) particles prepared by a zincothermic reduction at a mild temperature for high performance lithium-ion batteries which can operate in a wide temperature range. The optimized Ge battery anodes with the mesoporous structure exhibit outstanding electrochemical properties in a wide temperature ranging from -20 to 60 °C. Ge anodes exhibit a stable cycling retention at various temperatures (capacity retention of 99% after 100 cycles at 25 °C, 84% after 300 cycles at 60 °C, and 50% after 50 cycles at -20 °C). Furthermore, full cells consisting of the mesoporous Ge anode and an LiFePO 4 cathode show an excellent cyclability at -20 and 25 °C. Mesoporous Ge materials synthesized by the zincothermic reduction can be potentially applied as high performance anode materials for practical lithium-ion batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study on the pyrolysis of cellulose for bio-oil with mesoporous molecular sieve catalysts.

PubMed

Yu, Feng-wen; Ji, Deng-xiang; Nie, Yong; Luo, Yao; Huang, Cheng-jie; Ji, Jian-bing

2012-09-01

Mesoporous materials possess a hexagonal array of uniform mesopores, high surface areas, and moderate acidity. They are one of the important catalysts in the field of catalytic pyrolysis. In this paper, mesoporous materials of Al-MCM-41, La-Al-MCM-41, and Ce-Al-MCM-41 were synthesized, characterized, and tested as catalysts in the cellulose catalytic pyrolysis process using a fixed bed pyrolysis reactor. The results showed that mesoporous materials exhibited a strong influence on the pyrolytic behavior of cellulose. The presence of these mesoporous molecular sieve catalysts could vary the yield of products, which was that they could decrease the yield of liquid and char and increase the yield of gas product, and could promote high-carbon chain compounds to break into low-carbon chain compounds. Mesoporous molecular sieve catalysts were benefit to the reaction of dehydrogenation and deoxidation and the breakdown of carbon chain. Further, La-Al-MCM-41 and Ce-Al-MCM-41 catalysts can produce more toluene and 2-methoxy-phenol, as compared to the non-catalytic runs.

Performance of mesoporous organosilicates on the adsorption of heavy oil from produced water

NASA Astrophysics Data System (ADS)

Twaiq, Farouq A.; Nasser, Mustafa S.; Al-Ryiami, Samyia; Al-Ryiami, Hanan

2012-09-01

The performance of mesoporous organosilicate materials in removal of soluble oil from wastewater is investigated. The aim of the study is to evaluate the oil adsorption over organosilicate prepared using pre-synthesis methods and compare the results with adsorption over pure siliceous mesoporous material. The materials were prepared using sol-gel technique using Dodecylamine (D) and Cetyltrimethylammonium bromide (CTAB) as surfactant templates, and Tetraethylorthosilicate (TEOS) as silica precursor. The as-synthesized mesoporous materials were treated using three different methods to remove the surfactant from the mesoporous silica including calcinations method for total removal of the surfactant, the water vapor stripping and ethanol vapor stripping were used for partial removal of the surfactants. The synthesized materials were characterized using X-ray diffraction (XRD) and nitrogen adsorption. The materials were tested for heavy oils removal from oil-water solution. The results showed that neutral surfactant organosilicates have less adsorption compare to cationic surfactant organosilicates. The results also showed that among organosilicates prepared using neutral surfactant, treated organosilicate by ethanol vapor have the highest activity in removing the oil from the oil-water solution.

Crystalline mesoporous zirconia catalysts having stable tetragonal pore wall structure

DOEpatents

Sachtler, W.M.H.; Huang, Y.Y.

1998-07-28

Methods are disclosed for the preparation of new sulfated mesoporous zirconia materials/catalysts with crystalline pore walls of predominantly tetragonal crystal structure, characterized by nitrogen physical sorption measurement, X-ray diffraction, transmission electron microscopy and catalytic tests using n-butane isomerization to iso-butane and alkylation of 1-naphthol with 4-tert-butylstyrene as probe reactions. Sulfate deposition is preferred for the transformation of a mesoporous precursor with amorphous pore walls into a material with crystalline pore walls maintaining the mesoporous characteristics. 17 figs.

Crystalline mesoporous zirconia catalysts having stable tetragonal pore wall structure

DOEpatents

Sachtler, Wolfgang M. H.; Huang, Yin-Yan

1998-01-01

Methods for the preparation of new sulfated mesoporous zirconia materials/catalysts with crystalline pore walls of predominantly tetragonal crystal structure, characterized by nitrogen physisorption measurement, X-ray diffraction, transmission electron microscopy and catalytic tests using n-butane isomerization to iso-butane and alkylation of 1-naphthol with 4-tert-butylstyrene as probe reactions. Sulfate deposition is preferred for the transformation of a mesoporous precursor with amorphous pore walls into a material with crystalline pore walls maintaining the mesoporous characteristics.

Mesoporous systems for poorly soluble drugs.

PubMed

Xu, Wujun; Riikonen, Joakim; Lehto, Vesa-Pekka

2013-08-30

Utilization of inorganic mesoporous materials in formulations of poorly water-soluble drugs to enhance their dissolution and permeation behavior is a rapidly growing area in pharmaceutical materials research. The benefits of mesoporous materials in drug delivery applications stem from their large surface area and pore volume. These properties enable the materials to accommodate large amounts of payload molecules, protect them from premature degradation, and promote controlled and fast release. As carriers with various morphologies and chemical surface properties can be produced, these materials may even promote adsorption from the gastrointestinal tract to the systemic circulation. The main concern regarding their clinical applications is still the safety aspect even though most of them have been reported to be safely excreted, and a rather extensive toxicity screening has already been conducted with the most frequently studied mesoporous materials. In addition, the production of the materials on a large scale and at a reasonable cost may be a challenge when considering the utilization of the materials in industrial processes. However, if mesoporous materials could be employed in the industrial crystallization processes to produce hybrid materials with poorly soluble compounds, and hence to enhance their oral bioavailability, this might open new avenues for the pharmaceutical industry to employ nanotechnology in their processes. Copyright © 2012 Elsevier B.V. All rights reserved.

Macro-cellular silica foams: synthesis during the natural creaming process of an oil-in-water emulsion.

PubMed

Sen, T; Tiddy, G J T; Casci, J L; Anderson, M W

2003-09-07

The room-temperature synthesis of a macro-mesoporous silica material during the natural creaming process of an oil-in-water emulsion is reported. The material has 3-dimensional interconnected macropores with a strut-like structure similar to meso-cellular silica foams with mesoporous walls of worm-hole structure. The material has very high surface area (approximately 800 m2 g(-1)) with narrow mesopore size distribution.

"Bricks and mortar" self-assembly approach to graphitic mesoporous carbon nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fulvio, P. F.; Mayes, R.; Wang, X. Q.

2011-04-20

Mesoporous carbon materials do not have sufficient ordering at the atomic scale to exhibit good electronic conductivity. To date, mesoporous carbons having uniform mesopores and high surface areas have been prepared from partially-graphitizable precursors in the presence of templates. High temperature thermal treatments above 2000 °C, which are usually required to increase conductivity, result in a partial or total collapse of the mesoporous structures and reduced surface areas induced by growth of graphitic domains, limiting their applications in electric double layer capacitors and lithium-ion batteries. In this work, we successfully implemented a “brick-and-mortar” approach to obtain ordered graphitic mesoporous carbonmore » nanocomposites with tunable mesopore sizes below 850 °C without using graphitization catalysts or high temperature thermal treatments. Phenolic resin-based mesoporous carbons act as mortar to highly conductive carbon blacks and carbon onions (bricks). The capacitance and resistivity of final materials can be tailored by changing the mortar to brick ratios.« less

Brick-and-Mortar Self-Assembly Approach to Graphitic Mesoporous Carbon Nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Sheng; Fulvio, Pasquale F; Mayes, Richard T

2011-01-01

Mesoporous carbon materials do not have sufficient ordering at the atomic scale to exhibit good electronic conductivity. To date, mesoporous carbons having uniform mesopores and high surface areas have been prepared from partially-graphitizable precursors in the presence of templates. High temperature thermal treatments above 2000 C, which are usually required to increase conductivity, result in a partial or total collapse of the mesoporous structures and reduced surface areas induced by growth of graphitic domains, limiting their applications in electric double layer capacitors and lithium-ion batteries. In this work, we successfully implemented a 'brick-and-mortar' approach to obtain ordered graphitic mesoporous carbonmore » nanocomposites with tunable mesopore sizes below 850 C without using graphitization catalysts or high temperature thermal treatments. Phenolic resin-based mesoporous carbons act as mortar to highly conductive carbon blacks and carbon onions (bricks). The capacitance and resistivity of final materials can be tailored by changing the mortar to brick ratios.« less

Mesoporous Aluminosilicate Catalysts for the Selective Isomerization of n-Hexane: The Roles of Surface Acidity and Platinum Metal.

PubMed

Musselwhite, Nathan; Na, Kyungsu; Sabyrov, Kairat; Alayoglu, Selim; Somorjai, Gabor A

2015-08-19

Several types of mesoporous aluminosilicates were synthesized and evaluated in the catalytic isomerization of n-hexane, both with and without Pt nanoparticles loaded into the mesopores. The materials investigated included mesoporous MFI and BEA type zeolites, MCF-17 mesoporous silica, and an aluminum modified MCF-17. The acidity of the materials was investigated through pyridine adsorption and Fourier Transform-Infrared Spectroscopy (FT-IR). It was found that the strong Brönsted acid sites in the micropores of the zeolite catalysts facilitated the cracking of hexane. However, the medium strength acid sites on the Al modified MCF-17 mesoporous silica greatly enhanced the isomerization reaction. Through the loading of different amounts of Pt into the mesopores of the Al modified MCF-17, the relationship between the metal nanoparticles and acidic sites on the support was revealed.

Well-ordered mesoporous Fe2O3/C composites as high performance anode materials for sodium-ion batteries.

PubMed

Li, Mei; Ma, Chao; Zhu, Qian-Cheng; Xu, Shu-Mao; Wei, Xiao; Wu, Yong-Min; Tang, Wei-Ping; Wang, Kai-Xue; Chen, Jie-Sheng

2017-04-11

Sodium-ion batteries have attracted considerable attention in recent years. In order to promote the practical application of sodium-ion batteries, the electrochemical performances, such as specific capacity, reversibility, and rate capability of the anode materials, should be further improved. In this work, a Fe 2 O 3 /C composite with a well-ordered mesoporous structure is prepared via a facile co-impregnation method by using mesoporous silica SBA-15 as a hard template. When used as an anode material for sodium-ion batteries, the well-ordered mesoporous structure ensures fast mass transport kinetics. The presence of nano-sized Fe 2 O 3 particles confined within the carbon walls significantly enhances the specific capacity of the composite. The carbon walls in the composite act not only as an active material contributing to the specific capacity, but also as a conductive matrix improving the cycling stability of Fe 2 O 3 nanoparticles. As a result, the well-ordered mesoporous Fe 2 O 3 /C composite exhibits high specific capacity, excellent cycleability, and high rate capability. It is proposed that this simple co-impregnation method is applicable for the preparation of well-ordered mesoporous transition oxide/carbon composite electrode materials for high performance sodium-ion and lithium-ion batteries.

Bone tissue engineering using silica-based mesoporous nanobiomaterials:Recent progress.

PubMed

Shadjou, Nasrin; Hasanzadeh, Mohammad

2015-10-01

Bone disorders are of significant concern due to increase in the median age of our population. It is in this context that tissue engineering has been emerging as a valid approach to the current therapies for bone regeneration/substitution. Tissue-engineered bone constructs have the potential to alleviate the demand arising from the shortage of suitable autograft and allograft materials for augmenting bone healing. Silica based mesostructured nanomaterials possessing pore sizes in the range 2-50 nm and surface reactive functionalities have elicited immense interest due to their exciting prospects in bone tissue engineering. In this review we describe application of silica-based mesoporous nanomaterials for bone tissue engineering. We summarize the preparation methods, the effect of mesopore templates and composition on the mesopore-structure characteristics, and different forms of these materials, including particles, fibers, spheres, scaffolds and composites. Also, the effect of structural and textural properties of mesoporous materials on development of new biomaterials for production of bone implants and bone cements was discussed. Also, application of different mesoporous materials on construction of manufacture 3-dimensional scaffolds for bone tissue engineering was discussed. It begins by giving the reader a brief background on tissue engineering, followed by a comprehensive description of all the relevant components of silica-based mesoporous biomaterials on bone tissue engineering, going from materials to scaffolds and from cells to tissue engineering strategies that will lead to "engineered" bone. Copyright © 2015 Elsevier B.V. All rights reserved.

Mesoporous carbon materials

DOEpatents

Dai, Sheng; Fulvio, Pasquale Fernando; Mayes, Richard T.; Wang, Xiqing; Sun, Xiao-Guang; Guo, Bingkun

2014-09-09

A conductive mesoporous carbon composite comprising conductive carbon nanoparticles contained within a mesoporous carbon matrix, wherein the conductive mesoporous carbon composite possesses at least a portion of mesopores having a pore size of at least 10 nm and up to 50 nm, and wherein the mesopores are either within the mesoporous carbon matrix, or are spacings delineated by surfaces of said conductive carbon nanoparticles when said conductive carbon nanoparticles are fused with each other, or both. Methods for producing the above-described composite, devices incorporating them (e.g., lithium batteries), and methods of using them, are also described.

Functionalized SBA-15 materials for bilirubin adsorption

NASA Astrophysics Data System (ADS)

Tang, Tao; Zhao, Yanling; Xu, Yao; Wu, Dong; Xu, Jun; Deng, Feng

2011-05-01

To investigate the driving force for bilirubin adsorption on mesoporous materials, a comparative study was carried out between pure siliceous SBA-15 and three functionalized SBA-15 mesoporous materials: CH 3-SBA-15 (MS), NH 2-SBA-15 (AS), and CH 3/NH 2-SBA-15 (AMS) that were synthesized by one-pot method. The obtained materials exhibited large surface areas (553-810 m 2/g) and pore size (6.6-7.1 nm) demonstrated by XRD and N 2-ad/desorption analysis. The SEM images showed that the materials had similar fiberlike morphology. The functionalization extent was calculated according to 29Si MAS NMR spectra and it was close to the designed value (10%). The synthesized mesoporous materials were used as bilirubin adsorbents and showed higher bilirubin adsorption capacities than the commercial active carbon. The adsorption capacities of amine functionalized samples AMS and AS were larger than those of pure siliceous SBA-15 and MS, indicating that electrostatic interaction was the dominant driving force for bilirubin adsorption on mesoporous materials. Increasing the ionic strength of bilirubin solution by adding NaCl would decrease the bilirubin adsorption capacity of mesoporous material, which further demonstrated that the electrostatic interaction was the dominant driving force for bilirubin adsorption. In addition, the hydrophobic interaction provided by methyl groups could promote the bilirubin adsorption.

Recent advances of mesoporous materials in sample preparation.

PubMed

Zhao, Liang; Qin, Hongqiang; Wu, Ren'an; Zou, Hanfa

2012-03-09

Sample preparation has been playing an important role in the analysis of complex samples. Mesoporous materials as the promising adsorbents have gained increasing research interest in sample preparation due to their desirable characteristics of high surface area, large pore volume, tunable mesoporous channels with well defined pore-size distribution, controllable wall composition, as well as modifiable surface properties. The aim of this paper is to review the recent advances of mesoporous materials in sample preparation with emphases on extraction of metal ions, adsorption of organic compounds, size selective enrichment of peptides/proteins, specific capture of post-translational peptides/proteins and enzymatic reactor for protein digestion. Copyright © 2011 Elsevier B.V. All rights reserved.

Study of Horseradish Peroxidase Fixed on Mesoporous Materials as a Chemical Reaction Catalyst

NASA Astrophysics Data System (ADS)

Gao, Mengdan; Dai, Rongji

2017-12-01

Nanostructured mesoporous materials is a new type of porous materials, which has been widely used. It has excellent capability in enzymes immobilization, but modification on the chemical bonds of the enzyme reduce the enzymatic activity and rarely used in chemical reactions. The horseradish peroxidase was immobilized on the mesoporous materials with appropriate aperture and its activity and stability was evaluated when catalyzing the nitration reaction of amines and oxidation reaction of thiourea. The optimum mesoporous material to fix the horseradish peroxidase can be obtained by mixing polyoxyethylene - polyoxypropylene-pol, yoxyethylene(P123), 1,3,5-trimethylbenzene(TMB), and tetramethoxysilane (TMOS) at a ratio of 10:1:1, whose surface area and pore volume and pore diameter calculated by BET and BJH model were 402.903m2/g, 1.084cm2/g, 1.084cm2/g respectively. The horseradish peroxidase, immobilized on the mesoporous materials, was applied for catalyzing the nitration reaction of anilines and oxidation reaction of thiourea, produced a high product yield and can be recycled. Thus, it is a strong candidate as a catalysts for oxidation reactions, to be produced at industral scale, due to its high efficiency and low cost.

Multifunctional mesoporous silica catalyst

DOEpatents

Lin, Victor Shang-Yi; Tsai, Chih-Hsiang; Chen, Hung-Ting; Pruski, Marek; Kobayashi, Takeshi

2015-03-31

The present invention provides bifunctional silica mesoporous materials, including mesoporous silica nanoparticles ("MSN"), having pores modified with diarylammonium triflate and perfluoroaryl moieties, that are useful for the acid-catalyzed esterification of organic acids with organic alcohols.

Novel organic-inorganic hybrid mesoporous materials and nanocomposites

NASA Astrophysics Data System (ADS)

Feng, Qiuwei

Organic-inorganic hybrid mesoporous materials have been prepared successfully via the nonsurfactant templated sol-gel pathway using dibenzoyl-L-tartaric acid (DBTA) as the templating compound. Styrene and methyl methacrylate polymers have been incorporated into the mesoporous silica matrix on the molecular level. The synthetic conditions have been systematically studied and optimized. Titania based mesoporous materials have also been made using nonionic polyethylene glycol surfactant as the pore forming or structure-directing agent. In all of the above mesoporous materials, pore structures have been studied in detail by Transmission Electron Microscopy (TEM), X-ray diffraction and Brunauer-Emmett-Teller (BET) characterizations. The relationship between the template concentration and the pore parameters has been established. This nonsurfactant templated pathway possesses many advantages over the known surfactant approaches such as low cost, environment friendly and biocompatability. To overcome the drawback of nonsurfactant templated mesoporous materials that lack a well ordered pore structure, a flow induced synthesis has been attempted to orientate the sol-gel solution in order to obtain aligned pore structures. The versatility of this nonsurfactant templated pathway can even be extended to the making of organic-inorganic hybrid nanocomposite materials. On the basis of this approach, polymer-silica nanocomposite materials have been prepared using a polymerizable template. It is shown that the organic monomer such as hydroxyethyl methacrylate can act as a template in making nanoporous silica materials and then be further polymerized through a post synthesis technique. The properties and morphology of this new material have been studied by Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) and Infrared Absorption Spectroscopy (FTIR). Electroactive organic-inorganic hybrid materials have also been synthesized via the sol-gel process. A coupling agent was used to covalently bond the organic and inorganic species. The morphology and conductivity of the products have been investigated.

Mesoporous ZnS–NiS Nanocomposites for Nonenzymatic Electrochemical Glucose Sensors

PubMed Central

Wei, Chengzhen; Cheng, Cheng; Zhao, Junhong; Wang, Zhangtao; Wu, Haipeng; Gu, Kaiyue; Du, Weimin; Pang, Huan

2015-01-01

Mesoporous ZnS–NiS composites are prepared via ion- exchange reactions using ZnS as the precursor. The prepared mesoporous ZnS–NiS composite materials have large surface areas (137.9 m2 g−1) compared with the ZnS precursor. More importantly, the application of these mesoporous ZnS–NiS composites as nonenzymatic glucose sensors was successfully explored. Electrochemical sensors based on mesoporous ZnS–NiS composites exhibit a high selectivity and a low detection limit (0.125 μm) toward the oxidation of glucose, which can mainly be attributed to the morphological characteristics of the mesoporous structure with high specific surface area and a rational composition of the two constituents. In addition, the mesoporous ZnS–NiS composites coated on the surface of electrodes can be used to modify the mass transport regime, and this alteration can, in favorable circumstances, facilitate the amperometric discrimination between species. These results suggest that such mesoporous ZnS–NiS composites are promising materials for nonenzymatic glucose sensors. PMID:25861568

Soft-Templating Synthesis of Mesoporous Silica-Based Materials for Environmental Applications

NASA Astrophysics Data System (ADS)

Gunathilake, Chamila Asanka

Dissertation research is mainly focus on: 1) the development of mesoporous silica materials with organic pendant and bridging groups (isocyanurate, amidoxime, benzene) and incorporated metal (aluminum, zirconium, calcium, and magnesium) species for high temperature carbon dioxide (CO2) sorption, 2) phosphorous-hydroxy functionalized mesoporous silica materials for water treatment, and 3) amidoxime-modified ordered mesoporous silica materials for uranium sorption under seawater conditions. The goal is to design composite materials for environmental applications with desired porosity, surface area, and functionality by selecting proper metal oxide precursors, organosilanes, tetraethylorthosilicate, (TEOS), and block copolymer templates and by adjusting synthesis conditions. The first part of dissertation presents experimental studies on the merge of aluminum, zirconium, calcium, and magnesium oxides with mesoporous silica materials containing organic pendant (amidoxime) and bridging groups (isocyanurate, benzene) to obtain composite sorbents for CO2 sorption at ambient (0-25 °C) and elevated (60-120 °C) temperatures. These studies indicate that the aforementioned composite sorbents are fairly good for CO2 capture at 25 °C via physisorption mechanism and show a remarkably high affinity toward CO2 chemisorption at 60-120 °C. The second part of dissertation is devoted to silica-based materials with organic functionalities for removal of heavy metal ions such as lead from contaminated water and for recovery of metal ions such as uranium from seawater. First, ordered mesoporous organosilica (OMO) materials with diethylphosphatoethyl and hydroxyphosphatoethyl surface groups were examined for Pb2+ adsorption and showed unprecedented adsorption capacities up to 272 mg/g and 202 mg/g, respectively However, the amidoxime-modified OMO materials were explored for uranium extraction under seawater conditions and showed remarkable capacities reaching 57 mg of uranium per gram of adsorbent.

Soft templating strategies for the synthesis of mesoporous materials: inorganic, organic-inorganic hybrid and purely organic solids.

PubMed

Pal, Nabanita; Bhaumik, Asim

2013-03-01

With the discovery of MCM-41 by Mobil researchers in 1992 the journey of the research on mesoporous materials started and in the 21st century this area of scientific investigation have extended into numerous branches, many of which contribute significantly in emerging areas like catalysis, energy, environment and biomedical research. As a consequence thousands of publications came out in large varieties of national and international journals. In this review, we have tried to summarize the published works on various synthetic pathways and formation mechanisms of different mesoporous materials viz. inorganic, organic-inorganic hybrid and purely organic solids via soft templating pathways. Generation of nanoscale porosity in a solid material usually requires participation of organic template (more specifically surfactants and their supramolecular assemblies) called structure-directing agent (SDA) in the bottom-up chemical reaction process. Different techniques employed for the syntheses of inorganic mesoporous solids, like silicas, metal doped silicas, transition and non-transition metal oxides, mixed oxides, metallophosphates, organic-inorganic hybrids as well as purely organic mesoporous materials like carbons, polymers etc. using surfactants are depicted schematically and elaborately in this paper. Moreover, some of the frontline applications of these mesoporous solids, which are directly related to their functionality, composition and surface properties are discussed at the appropriate places. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis of mesoporous silica materials (MCM-41) from iron ore tailings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu Honghao, E-mail: honghaoyu@hotmail.com; College of Material Science and Engineering, Shenyang Ligong University, Shenyang, 110168; Xue Xiangxin

2009-11-15

Highly ordered mesoporous materials were successfully synthesized by using the iron ore tailings as the silica source and n-hexadecyltrimethyl ammonium bromide as the template. The samples were detail characterized by powder X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy and N{sub 2} physisorption. The as-synthesized materials had high surface area of 527 m{sup 2} g{sup -1} and the mean pore diameter of 2.65 nm with a well-ordered two-dimensional hexagonal structure. It is feasible to prepare mesoporous MCM-41 materials using the iron ore tailings as precursor.

Hierarchical Metal–Organic Framework Hybrids: Perturbation-Assisted Nanofusion Synthesis

DOE PAGES

Yue, Yanfeng; Fulvio, Pasquale F.; Dai, Sheng

2015-12-04

Metal–organic frameworks (MOFs) represent a new family of microporous materials; however, microporous–mesoporous hierarchical MOF materials have been less investigated because of the lack of simple, reliable methods to introduce mesopores to the crystalline microporous particles. State-of-the-art MOF hierarchical materials have been prepared by ligand extension methods or by using a template, resulting in intrinsic mesopores of longer ligands or replicated pores from template agents, respectively. However, mesoporous MOF materials obtained through ligand extension often collapse in the absence of guest molecules, which dramatically reduces the size of the pore aperture. Although the template-directed strategy allows for the preparation of hierarchicalmore » materials with larger mesopores, the latter requires a template removal step, which may result in the collapse of the implemented mesopores. Recently, a general template-free synthesis of hierarchical microporous crystalline frameworks, such as MOFs and Prussian blue analogues (PBAs), has been reported. Our new method is based on the kinetically controlled precipitation (perturbation), with simultaneous condensation and redissolution of polymorphic nanocrystallites in the mother liquor. This method further eliminates the use of extended organic ligands and the micropores do not collapse upon removal of trapped guest solvent molecules, thus yielding hierarchical MOF materials with intriguing porosity in the gram scale. The hierarchical MOF materials prepared in this way exhibited exceptional properties when tested for the adsorption of large organic dyes over their corresponding microporous frameworks, due to the enhanced pore accessibility and electrolyte diffusion within the mesopores. As for PBAs, the pore size distribution of these materials can be tailored by changing the metals substituting Fe cations in the PB lattice. For these, the textural mesopores increased from approximately 10 nm for Cu analogue (mesoCuHCF), to 16 nm in Co substituted compound (mesoCoHCF), and to as large as 30 nm for the Ni derivative (mesoNiHCF). And while bulk PB and analogues have a higher capacitance than hierarchical analogues for Na-batteries, the increased accessibility to the microporous channels of PBAs allow for faster intercalated ion exchange and diffusion than in bulk PBA crystals. Therefore, hierarchical PBAs are promising candidates for electrodes in future electrochemical energy storage devices with faster charge–discharge rates than batteries, namely pseudocapacitors. Finally, this new synthetic method opens the possibility to prepare hierarchical materials having bimodal distribution of mesopores, and to tailor the structural properties of MOFs for different applications, including contrasting agents for MRI, and drug delivery.« less

Experimental and theoretical investigation of a mesoporous KxWO3 material having superior mechanical strength

NASA Astrophysics Data System (ADS)

Dey, Sonal; Anderson, Sean T.; Mayanovic, Robert A.; Sakidja, Ridwan; Landskron, Kai; Kokoszka, Berenika; Mandal, Manik; Wang, Zhongwu

2016-01-01

Mesoporous materials with tailored properties hold great promise for energy harvesting and industrial applications. We have synthesized a novel tungsten bronze mesoporous material (KxWO3; x ~ 0.07) having inverse FDU-12 type pore symmetry and a crystalline framework. In situ small angle X-ray scattering (SAXS) measurements of the mesoporous K0.07WO3 show persistence of a highly ordered meso-scale pore structure to high pressure conditions (~18.5 GPa) and a material with remarkable mechanical strength despite having ~35% porosity. Pressure dependent in situ SAXS measurements reveal a bulk modulus κ = 44 +/- 4 GPa for the mesoporous KxWO3 which is comparable to the corresponding value for the bulk monoclinic WO3 (γ-WO3). Evidence from middle angle (MAXS) and wide angle X-ray scattering (WAXS), high-resolution transmission electron microscopy (HR-TEM) and Raman spectroscopy shows that the presence of potassium leads to the formation of a K-bearing orthorhombic tungsten bronze (OTB) phase within a monoclinic WO3 host structure. Our ab initio molecular dynamics calculations show that the formation of the OTB phase provides superior strength to the mesoporous K0.07WO3.Mesoporous materials with tailored properties hold great promise for energy harvesting and industrial applications. We have synthesized a novel tungsten bronze mesoporous material (KxWO3; x ~ 0.07) having inverse FDU-12 type pore symmetry and a crystalline framework. In situ small angle X-ray scattering (SAXS) measurements of the mesoporous K0.07WO3 show persistence of a highly ordered meso-scale pore structure to high pressure conditions (~18.5 GPa) and a material with remarkable mechanical strength despite having ~35% porosity. Pressure dependent in situ SAXS measurements reveal a bulk modulus κ = 44 +/- 4 GPa for the mesoporous KxWO3 which is comparable to the corresponding value for the bulk monoclinic WO3 (γ-WO3). Evidence from middle angle (MAXS) and wide angle X-ray scattering (WAXS), high-resolution transmission electron microscopy (HR-TEM) and Raman spectroscopy shows that the presence of potassium leads to the formation of a K-bearing orthorhombic tungsten bronze (OTB) phase within a monoclinic WO3 host structure. Our ab initio molecular dynamics calculations show that the formation of the OTB phase provides superior strength to the mesoporous K0.07WO3. Electronic supplementary information (ESI) available: Experimental details of SEM and TEM measurements, SAXS data analysis, the procedure for Rietveld refinement, peak fitting for the Raman results, the modelling approach, UV-Vis and N2 sorption measurements. See DOI: 10.1039/c5nr07941a

Prototype of low thermal expansion materials: fabrication of mesoporous silica/polymer composites with densely filled polymer inside mesopore space.

PubMed

Kiba, Shosuke; Suzuki, Norihiro; Okawauchi, Yoshinori; Yamauchi, Yusuke

2010-09-03

A prototype of novel low thermal expansion materials using mesoporous silica particles is demonstrated. Mesoporous silica/polymer composites with densely filled polymer inside the mesopore space are fabricated by mechanically mixing both organically modified mesoporous silica and epoxy polymer. The mesopores are easily penetrated by polymers as a result of the capillary force during the mechanical composite processing. Furthermore, we propose a new model of polymer mobility restriction using mesoporous silica with a large pore space. The robust inorganic frameworks covering the polymer effectively restrict the polymer mobility against thermal energy. As a result, the degree of total thermal expansion of the composites is drastically decreased. From the mass-normalized thermal mechanical analysis (TMA) charts of various composites with different amounts of mesoporous silica particles, it is observed that the coefficient of thermal expansion (CTE) values gradually increase with an increase of the polymer amount outside the mesopores. It is proven that the CTE values in the range over the glass-transition temperatures (T(g)) are perfectly proportional to the outside polymer amounts. Importantly, the Y-intercept of the relation equation obtained by a least-square method is the CTE value and is almost zero. This means that thermal expansion does not occur if no polymers are outside the mesopores. Through such a quantative discussion, we clarify that only the outside polymer affects the thermal expansion of the composites, that is, the embedded polymers inside the mesopores do not expand at all during the thermal treatment.

Mesoporous Silicate Materials in Sensing

PubMed Central

Melde, Brian J.; Johnson, Brandy J.; Charles, Paul T.

2008-01-01

Mesoporous silicas, especially those exhibiting ordered pore systems and uniform pore diameters, have shown great potential for sensing applications in recent years. Morphological control grants them versatility in the method of deployment whether as bulk powders, monoliths, thin films, or embedded in coatings. High surface areas and pore sizes greater than 2 nm make them effective as adsorbent coatings for humidity sensors. The pore networks also provide the potential for immobilization of enzymes within the materials. Functionalization of materials by silane grafting or through co-condensation of silicate precursors can be used to provide mesoporous materials with a variety of fluorescent probes as well as surface properties that aid in selective detection of specific analytes. This review will illustrate how mesoporous silicas have been applied to sensing changes in relative humidity, changes in pH, metal cations, toxic industrial compounds, volatile organic compounds, small molecules and ions, nitroenergetic compounds, and biologically relevant molecules. PMID:27873810

Bio-templated synthesis of highly ordered macro-mesoporous silica material for sustained drug delivery

NASA Astrophysics Data System (ADS)

Qu, Fengyu; Lin, Huiming; Wu, Xiang; Li, Xiaofeng; Qiu, Shilun; Zhu, Guangshan

2010-05-01

The bimodal porous structured silica materials consisting of macropores with the diameter of 5-20 μm and framework-like mesopores with the diameter of 4.7-6.0 nm were prepared using natural Manchurian ash and mango linin as macropored hard templates and P123 as mesopore soft templates, respectively. The macroporous structures of Manchurian ash and mango linin were replicated with the walls containing highly ordered mesoporous silica as well. As-synthesized dual porous silica was characterized by scanning electron microscope (SEM), powder X-ray diffraction (XRD), transmission electron microscope (TEM) and nitrogen adsorption/desorption, fourier transform IR (FTIR) spectroscopy, and thermo-gravimetric analyzer (TGA). Ibuprofen (Ibu) was employed as a model drug and the release profiles showed that the dual porous material had a sustained drug delivery capability. And such highly ordered dual pore silica materials may have potential applications for bimolecular adsorption/separation and tissue repairing.

High-pressure synthesis of mesoporous stishovite: potential applications in mineral physics

NASA Astrophysics Data System (ADS)

Stagno, Vincenzo; Mandal, Manik; Landskron, Kai; Fei, Yingwei

2015-06-01

Recently, we have described a successful synthesis route to obtain mesoporous quartz and its high-pressure polymorph coesite by nanocasting at high pressure using periodic mesostructured precursors, such as SBA-16 and FDU-12/carbon composite as starting materials. Periodic mesoporous high-pressure silica polymorphs are of particular interest as they combine transport properties and physical properties such as hardness that potentially enable the industrial use of these materials. In addition, synthesis of mesoporous crystalline silica phases can allow more detailed geology-related studies such as water/mineral interaction, dissolution/crystallization rate and the surface contribution to the associated thermodynamic stability (free energy and enthalpy) of the various polymorphs and their crossover. Here, we present results of synthesis of mesoporous stishovite from cubic large-pore periodic mesoporous silica LP-FDU-12/C composite as precursor with an fcc lattice. We describe the synthesis procedure using multi-anvil apparatus at 9 GPa (about 90,000 atm) and temperature of 500 °C. The synthetic mesoporous stishovite is, then, characterized by wide and small-angle X-ray diffraction, scanning/transmission electron microscopy and gas adsorption. Results show that this new material is characterized by accessible mesopores with wide pore size distribution, surface area of ~45 m2/g and volume of pores of ~0.15 cm3/g. Results from gas adsorption indicate that both porosity and permeability are retained at the high pressures of synthesis but with weak periodic order of the pores.

X-ray absorption spectroscopic studies on gold nanoparticles in mesoporous and microporous materials.

PubMed

Akolekar, Deepak B; Foran, Garry; Bhargava, Suresh K

2004-05-01

Au L(3)-edge X-ray absorption spectroscopic measurements were carried out over a series of mesoporous and microporous materials containing gold nanoparticles to investigate the effects of the host matrix and preparation methods on the properties of gold nanoparticles. The materials of structure type MCM-41, ZSM-5, SAPO-18 and LSX with varying framework composition containing low concentrations of gold nanoparticles were prepared and characterized. In these materials the size of the gold nanoparticles varied in the range approximately 1 to 4 nm. A series of gold nanoparticles within different mesoporous and microporous materials have been investigated using X-ray absorption fine structure (XANES, EXAFS) and other techniques. Information such as atomic distances, bonding and neighbouring environment obtained from XAFS measurements was useful in elucidating the nature and structure of gold nanoparticles on these catalytic materials. The influence of the high-temperature (823, 1113, 1273 K) treatment on gold nanoparticles inside the mesoporous matrix was investigated using the XAFS technique. The XAFS and XANES results confirm various characteristics of gold nanoparticles in these materials suitable for catalysis, fabrication of nanodevices and other applications.

Functional mesoporous materials for energy applications: solar cells, fuel cells, and batteries

NASA Astrophysics Data System (ADS)

Ye, Youngjin; Jo, Changshin; Jeong, Inyoung; Lee, Jinwoo

2013-05-01

This feature article presents recent progress made in the synthesis of functional ordered mesoporous materials and their application as high performance electrodes in dye-sensitized solar cells (DSCs) and quantum dot-sensitized solar cells (QDSCs), fuel cells, and Li-ion batteries. Ordered mesoporous materials have been mainly synthesized using two representative synthetic methods: the soft template and hard template methods. To overcome the limitations of these two methods, a new method called CASH was suggested. The CASH method combines the advantages of the soft and hard template methods by employing a diblock copolymer, PI-b-PEO, which contains a hydrophilic block and an sp2-hybridized-carbon-containing hydrophobic block as a structure-directing agent. After discussing general techniques used in the synthesis of mesoporous materials, this article presents recent applications of mesoporous materials as electrodes in DSCs and QDSCs, fuel cells, and Li-ion batteries. The role of material properties and mesostructures in device performance is discussed in each case. The developed soft and hard template methods, along with the CASH method, allow control of the pore size, wall composition, and pore structure, providing insight into material design and optimization for better electrode performances in these types of energy conversion devices. This paper concludes with an outlook on future research directions to enable breakthroughs and overcome current limitations in this field.

Functional mesoporous materials for energy applications: solar cells, fuel cells, and batteries.

PubMed

Ye, Youngjin; Jo, Changshin; Jeong, Inyoung; Lee, Jinwoo

2013-06-07

This feature article presents recent progress made in the synthesis of functional ordered mesoporous materials and their application as high performance electrodes in dye-sensitized solar cells (DSCs) and quantum dot-sensitized solar cells (QDSCs), fuel cells, and Li-ion batteries. Ordered mesoporous materials have been mainly synthesized using two representative synthetic methods: the soft template and hard template methods. To overcome the limitations of these two methods, a new method called CASH was suggested. The CASH method combines the advantages of the soft and hard template methods by employing a diblock copolymer, PI-b-PEO, which contains a hydrophilic block and an sp(2)-hybridized-carbon-containing hydrophobic block as a structure-directing agent. After discussing general techniques used in the synthesis of mesoporous materials, this article presents recent applications of mesoporous materials as electrodes in DSCs and QDSCs, fuel cells, and Li-ion batteries. The role of material properties and mesostructures in device performance is discussed in each case. The developed soft and hard template methods, along with the CASH method, allow control of the pore size, wall composition, and pore structure, providing insight into material design and optimization for better electrode performances in these types of energy conversion devices. This paper concludes with an outlook on future research directions to enable breakthroughs and overcome current limitations in this field.

The unusual electrochemical characteristics of a novel three-dimensional ordered bicontinuous mesoporous carbon

NASA Astrophysics Data System (ADS)

Wang, Tao; Liu, Xiaoying; Zhao, Dongyuan; Jiang, Zhiyu

2004-05-01

The electrochemical properties of the ordered three-dimensional (3D) mesoporous carbon, synthesized by using mesoporous silica (FDU-5) as a hard template from an impregnation procedure, has been firstly explored as an anode material for lithium-ion batteries. The material presents uniform pore size of 7.4 nm, BET surface area of 750 m 2/g. As a novel nano-material C-FDU-5 shows almost constant resistance and Li + diffusion coefficient when the potential is lower than the critical potential. The material also presents a reversible capacity higher than that of carbon nanotubes, and can be charge/discharged at the large current rate.

Chemistry of Mesoporous Organosilica in Nanotechnology: Molecularly Organic-Inorganic Hybridization into Frameworks.

PubMed

Chen, Yu; Shi, Jianlin

2016-05-01

Organic-inorganic hybrid materials aiming to combine the individual advantages of organic and inorganic components while overcoming their intrinsic drawbacks have shown great potential for future applications in broad fields. In particular, the integration of functional organic fragments into the framework of mesoporous silica to fabricate mesoporous organosilica materials has attracted great attention in the scientific community for decades. The development of such mesoporous organosilica materials has shifted from bulk materials to nanosized mesoporous organosilica nanoparticles (designated as MONs, in comparison with traditional mesoporous silica nanoparticles (MSNs)) and corresponding applications in nanoscience and nanotechnology. In this comprehensive review, the state-of-art progress of this important hybrid nanomaterial family is summarized, focusing on the structure/composition-performance relationship of MONs of well-defined morphology, nanostructure, and nanoparticulate dimension. The synthetic strategies and the corresponding mechanisms for the design and construction of MONs with varied morphologies, compositions, nanostructures, and functionalities are overviewed initially. Then, the following part specifically concentrates on their broad spectrum of applications in nanotechnology, mainly in nanomedicine, nanocatalysis, and nanofabrication. Finally, some critical issues, presenting challenges and the future development of MONs regarding the rational synthesis and applications in nanotechnology are summarized and discussed. It is highly expected that such a unique molecularly organic-inorganic nanohybrid family will find practical applications in nanotechnology, and promote the advances of this discipline regarding hybrid chemistry and materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-surface Thermally Stable Mesoporous Gallium Phosphates Constituted by Nanoparticles as Primary Building Blocks

DOE Office of Scientific and Technical Information (OSTI.GOV)

V Parvulescu; V Parvulescu; D Ciuparu

In constant, search for micro/mesoporous materials, gallium phosphates, have attracted continued interest due to the large pore size reported for some of these solids in comparison with analogous aluminum phosphates. However up to now, the porosity of gallium phosphates collapsed upon template removal or exposure to the ambient moisture. In the present work, we describe high-surface thermally stable mesoporous gallium phosphates synthesized from gallium propoxide and PCl{sub 3} and different templating agents such as amines (dipropylamine, piperidine and aminopiperidine) and quaternary ammonium salts (C{sub 16}H{sub 33}(CH{sub 3})3NBr and C{sub 16}PyCl). These highly reactive precursors have so far not been usedmore » as gallium and phosphate sources for the synthesis of gallophosphates. Conceptually, our present synthetic procedure is based on the fast formation of gallium phosphate nanoparticles via the reaction of gallium propoxide with PCl{sub 3} and subsequent construction of the porous material with nanoparticles as building blocks. The organization of the gallophosphate nanoparticles in stable porous structures is effected by the templates. Different experimental procedures varying the molar composition of the sol-gel, pH and the pretreatment of gallium precursor were assayed, most of them leading to satisfactory materials in terms of thermal stability and porosity. In this way, a series of gallium phosphates with surface are above 200 m{sup 2} g{sup -1}, and narrow pore size from 3 to 6 nm and remarkable thermal stability (up to 550 C) have been prepared. In some cases, the structure tends to show some periodicity and regularity as determined by XRD. The remarkable stability has allowed us to test the catalytic activity of gallophosphates for the aerobic oxidation of alkylaromatics with notable good results. Our report reopens the interest for gallophosphates in heterogeneous catalysis.« less

Hierarchical Composites to Reduce N-Nitrosamines in Cigarette Smoke

PubMed Central

Li, Yan Yan; Cao, Yi; Yue, Ming Bo; Yang, Jing; Zhu, Jian Hua

2015-01-01

In order to reduce the harmful constituents in cigarette smoke, two hierarchical composites were synthesized. Based on, zeolites HZSM-5 or NaY fragments were introduced into the synthetic system of mesoporous silica SBA-15 or MCM-41 and assembled with the mesoporous materials. These porous composites combine the advantages of micro- and mesoporous materials, and exhibit higher effects than activated carbon on reducing tobacco specific nitrosamines (TSNA) and some vapor phase compounds in smoke. PMID:28788003

Monolithic Gyroidal Mesoporous Mixed Titanium–Niobium Nitrides

PubMed Central

2015-01-01

Mesoporous transition metal nitrides are interesting materials for energy conversion and storage applications due to their conductivity and durability. We present ordered mixed titanium–niobium (8:2, 1:1) nitrides with gyroidal network structures synthesized from triblock terpolymer structure-directed mixed oxides. The materials retain both macroscopic integrity and mesoscale ordering despite heat treatment up to 600 °C, without a rigid carbon framework as a support. Furthermore, the gyroidal lattice parameters were varied by changing polymer molar mass. This synthesis strategy may prove useful in generating a variety of monolithic ordered mesoporous mixed oxides and nitrides for electrode and catalyst materials. PMID:25122534

Mesoporous aluminium organophosphonates: a reusable chemsensor for the detection of explosives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Dongdong, E-mail: lidongdong@jlu.edu.cn; Yu, Xiang

Rapid and sensitive detection of explosives is in high demand for homeland security and public safety. In this work, electron-rich of anthracene functionalized mesoporous aluminium organophosphonates (En-AlPs) were synthesized by a one-pot condensation process. The mesoporous structure and strong blue emission of En-AlPs were confirmed by the N{sub 2} adsorption-desorption isotherms, transmission electron microscopy images and fluorescence spectra. The materials En-AlPs can serve as sensitive chemosensors for various electron deficient nitroderivatives, with the quenching constant and the detection limit up to 1.5×10{sup 6} M{sup −1} and 0.3 ppm in water solution. More importantly, the materials can be recycled for manymore » times by simply washed with ethanol, showing potential applications in explosives detection. - Graphical abstract: Electron-rich of anthracene functionalized mesoporous aluminium organophosphonates can serve as sensitive and recycled chemosensors for nitroderivatives with the quenching constant up to 1.5×10{sup 6} M{sup −1} in water solution. Display Omitted - Highlights: • Anthracene functionalized mesoporous aluminium organophosphonates were synthesized. • The materials serve as sensitive chemosensors for nitroderivatives. • The materials can be recycled for many times by simply washed with ethanol. • The materials show potential applications in explosives detection.« less

Synthesis and characterization of SBA-3, SBA-15, and SBA-1 nanostructured catalytic materials.

PubMed

Anunziata, Oscar A; Beltramone, Andrea R; Martínez, Maria L; Belon, Lizandra López

2007-11-01

A highly ordered large pore mesoporous silica molecular sieve SBA-3, SBA-15, Al-SBA-15, and SBA-1, were developed and characterized by XRD, BET, FTIR, SEM, and NMR-MAS. The catalytic materials were synthesized using different raw materials and operation conditions. These materials contain a regular arrangement of uniform channels with diameters between 1.8 and 10 nm, high specific surface area and high specific pore volume. The designed methods were effective for the synthesis, presenting each mesostructured materials, patterns of XRD and other characteristics corresponding to the reported ones in literature. The new route employed to synthesize Al-SBA-15, generates a catalyst with only aluminum in tetrahedral form, according to the data of (27)Al NMR-MAS. However, several reports indicated that the coordination of the Al atoms changes below the Si/Al ratio of 45, presenting peaks corresponding to penta and hexa-coordinated aluminum, which are absent in our samples (Si/Al = 50 and 33).

A Review: Fundamental Aspects of Silicate Mesoporous Materials

PubMed Central

ALOthman, Zeid A.

2012-01-01

Silicate mesoporous materials have received widespread interest because of their potential applications as supports for catalysis, separation, selective adsorption, novel functional materials, and use as hosts to confine guest molecules, due to their extremely high surface areas combined with large and uniform pore sizes. Over time a constant demand has developed for larger pores with well-defined pore structures. Silicate materials, with well-defined pore sizes of about 2.0–10.0 nm, surpass the pore-size constraint (<2.0 nm) of microporous zeolites. They also possess extremely high surface areas (>700 m2 g−1) and narrow pore size distributions. Instead of using small organic molecules as templating compounds, as in the case of zeolites, long chain surfactant molecules were employed as the structure-directing agent during the synthesis of these highly ordered materials. The structure, composition, and pore size of these materials can be tailored during synthesis by variation of the reactant stoichiometry, the nature of the surfactant molecule, the auxiliary chemicals, the reaction conditions, or by post-synthesis functionalization techniques. This review focuses mainly on a concise overview of silicate mesoporous materials together with their applications. Perusal of the review will enable researchers to obtain succinct information about microporous and mesoporous materials.

Mesoporous carbon nanomaterials in drug delivery and biomedical application.

PubMed

Zhao, Qinfu; Lin, Yuanzhe; Han, Ning; Li, Xian; Geng, Hongjian; Wang, Xiudan; Cui, Yu; Wang, Siling

2017-01-01

Recent development of nano-technology provides highly efficient and versatile treatment methods to achieve better therapeutic efficacy and lower side effects of malignant cancer. The exploration of drug delivery systems (DDSs) based on nano-material shows great promise in translating nano-technology to clinical use to benefit patients. As an emerging inorganic nanomaterial, mesoporous carbon nanomaterials (MCNs) possess both the mesoporous structure and the carbonaceous composition, endowing them with superior nature compared with mesoporous silica nanomaterials and other carbon-based materials, such as carbon nanotube, graphene and fullerene. In this review, we highlighted the cutting-edge progress of carbon nanomaterials as drug delivery systems (DDSs), including immediate/sustained drug delivery systems and controlled/targeted drug delivery systems. In addition, several representative biomedical applications of mesoporous carbon such as (1) photo-chemo synergistic therapy; (2) delivery of therapeutic biomolecule and (3) in vivo bioimaging are discussed and integrated. Finally, potential challenges and outlook for future development of mesoporous carbon in biomedical fields have been discussed in detail.

Versatility of Evaporation-Induced Self-Assembly (EISA) Method for Preparation of Mesoporous TiO2 for Energy and Environmental Applications

PubMed Central

Mahoney, Luther; Koodali, Ranjit T.

2014-01-01

Evaporation-Induced Self-Assembly (EISA) method for the preparation of mesoporous titanium dioxide materials is reviewed. The versatility of EISA method for the rapid and facile synthesis of TiO2 thin films and powders is highlighted. Non-ionic surfactants such as Pluronic P123, F127 and cationic surfactants such as cetyltrimethylammonium bromide have been extensively employed for the preparation of mesoporous TiO2. In particular, EISA method allows for fabrication of highly uniform, robust, crack-free films with controllable thickness. Eleven characterization techniques for elucidating the structure of the EISA prepared mesoporous TiO2 are discussed in this paper. These many characterization methods provide a holistic picture of the structure of mesoporous TiO2. Mesoporous titanium dioxide materials have been employed in several applications that include Dye Sensitized Solar Cells (DSSCs), photocatalytic degradation of organics and splitting of water, and batteries. PMID:28788590

Functionalized mesoporous silica materials for molsidomine adsorption: Thermodynamic study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alyoshina, Nonna A.; Parfenyuk, Elena V., E-mail: evp@iscras.ru

2013-09-15

A series of unmodified and organically modified mesoporous silica materials was prepared. The unmodified mesoporous silica was synthesized via sol–gel synthesis in the presence of D-glucose as pore-forming agent. The functionalized by phenyl, aminopropyl and mercaptopropyl groups silica materials were prepared via grafting. The fabricated adsorbent materials were characterized by Fourier transform infrared spectroscopy (FTIR) analysis, N{sub 2} adsorption/desorption and elemental analysis methods. Then their adsorption properties for mesoionic dug molsidomine were investigated at 290–313 K and physiological pH value. Thermodynamic parameters of molsidomine adsorption on the synthesized materials have been calculated. The obtained results showed that the adsorption processmore » of molsidomine on the phenyl modified silica is the most quantitatively and energetically favorable. The unmodified and mercaptopropyl modified silica materials exhibit significantly higher adsorption capacities and energies for molsidomine than the aminopropyl modified sample. The effects are discussed from the viewpoint of nature of specific interactions responsible for the adsorption. - Graphical abstract: Comparative analysis of the thermodynamic characteristics of molsidomine adsorption showed that the adsorption process on mesoporous silica materials is controlled by chemical nature of surface functional groups. Molsidomine adsorption on the phenyl modified silica is the most quantitatively and energetically favorable. Taking into account ambiguous nature of mesoionic compounds, it was found that molsidomine is rather aromatic than dipolar. Display Omitted - Highlights: • Unmodified and organically modified mesoporous silica materials were prepared. • Molsidomine adsorption on the silica materials was studied. • Phenyl modified silica shows the highest adsorption capacity and favorable energy. • Molsidomine exhibits the lowest affinity to aminopropyl modified silica.« less

Controllable self-assembly of mesoporous hydroxyapatite.

PubMed

Chen, Jingdi; Wang, Zihao; Wen, Zhenliang; Yang, Shen; Wang, Jianhua; Zhang, Qiqing

2015-03-01

In this paper, mesoporous hydroxyapatite (HAp) of controllable pore size was tailored with the template of a biodegradable mono-alkyl phosphate (MAP) via a simple route by hydrothermal treatment. A serial study of the various experimental parameters on pore size of HAp was investigated. The additive amount of MAP and hydrothermal temperature were important factors for the pore structure and pore size. Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption-desorption (BET, BJH) were used to characterize the structure and composition of the HAp samples. Both XRD and BJH results indicated that regular mesoporous HAp nanoparticles (with a mean pore size of 3.5nm) were successfully produced. As shown in transmission electron microscopy (TEM), orderly uniform pore structure appeared in the HAp particles. Because of the special structure of the MAP and the interaction between ionized MAP and other ions in solution, the product presents uniform mesoporous structure with well-defined pore size. Copyright © 2015 Elsevier B.V. All rights reserved.

Mesoporous silica formulation strategies for drug dissolution enhancement: a review.

PubMed

McCarthy, Carol A; Ahern, Robert J; Dontireddy, Rakesh; Ryan, Katie B; Crean, Abina M

2016-01-01

Silica materials, in particular mesoporous silicas, have demonstrated excellent properties to enhance the oral bioavailability of poorly water-soluble drugs. Current research in this area is focused on investigating the kinetic profile of drug release from these carriers and manufacturing approaches to scale-up production for commercial manufacture. This review provides an overview of different methods utilized to load drugs onto mesoporous silica carriers. The influence of silica properties and silica pore architecture on drug loading and release are discussed. The kinetics of drug release from mesoporous silica systems is examined and the manufacturability and stability of these formulations are reviewed. Finally, the future prospects of mesoporous silica drug delivery systems are considered. Substantial progress has been made in the characterization and development of mesoporous drug delivery systems for drug dissolution enhancement. However, more research is required to fully understand the drug release kinetic profile from mesoporous silica materials. Incomplete drug release from the carrier and the possibility of drug re-adsorption onto the silica surface need to be investigated. Issues to be addressed include the manufacturability and regulation status of formulation approaches employing mesoporous silica to enhance drug dissolution. While more research is needed to support the move of this technology from the bench to a commercial medicinal product, it is a realistic prospect for the near future.

A controlled release of ibuprofen by systematically tailoring the morphology of mesoporous silica materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qu Fengyu; Chemistry and Pharmaceutical College, Jiamusi University, Jiamusi 154007; Zhu Guangshan

2006-07-15

A series of mesoporous silica materials with similar pore sizes, different morphologies and variable pore geometries were prepared systematically. In order to control drug release, ibuprofen was employed as a model drug and the influence of morphology and pore geometry of mesoporous silica on drug release profiles was extensively studied. The mesoporous silica and drug-loaded samples were characterized by X-ray diffraction, Fourier transform IR spectroscopy, N{sub 2} adsorption and desorption, scanning electron microscopy, and transmission electron microscopy. It was found that the drug-loading amount was directly correlated to the Brunauer-Emmett-Teller surface area, pore geometry, and pore volume; while the drugmore » release profiles could be controlled by tailoring the morphologies of mesoporous silica carriers. - Graphical abstract: The release of ibuprofen is controlled by tailoring the morphologies of mesoporous silica. The mesoporous silica and drug-loaded samples are characterized by powder X-ray diffraction, Fourier transform IR spectroscopy, N{sub 2} adsorption and desorption, scanning electron microscopy, and transmission electron microscopy. The drug-loading amount is directly correlated to the Brunauer-Emmett-Teller surface area, pore geometry, and pore volume; while the drug release profiles can be controlled by tailoring the morphologies of mesoporous silica carriers.« less

Simple Preparation of Novel Metal-Containing Mesoporous Starches †

PubMed Central

Ojeda, Manuel; Budarin, Vitaliy; Shuttleworth, Peter S.; Clark, James H.; Pineda, Antonio; Balu, Alina M.; Romero, Antonio A.; Luque, Rafael

2013-01-01

Metal-containing mesoporous starches have been synthesized using a simple and efficient microwave-assisted methodology followed by metal impregnation in the porous gel network. Final materials exhibited surface areas >60 m2 g−1, being essentially mesoporous with pore sizes in the 10–15 nm range with some developed inter-particular mesoporosity. These materials characterized by several techniques including XRD, SEM, TG/DTA and DRIFTs may find promising catalytic applications due to the presence of (hydr)oxides in their composition. PMID:28809249

Effect of Solvent Variations in the Alcothermal Synthesis of Template-Free Mesoporous Titania for Dye-Sensitized Solar Cells Applications

PubMed Central

Wawrzyńczak, Agata; Półrolniczak, Paulina; Sobuś, Jan; Schroeder, Grzegorz; Jurga, Stefan; Selli, Elena

2016-01-01

A series of 14 mesoporous titania materials has been synthesized using the simple alcothermal template-free method and various alcohols, such as methanol, propanols and butanols, as solvents. All materials were characterized by both wide and small angle XRD, which exhibited the anatase phase with short-range ordered mesoporous structure that is still forming during post synthetic temperature treatment in most of the investigated materials. Nitrogen adsorption–desorption isotherms confirmed the mesoporous structure with surface area ranging from 241 to 383 m2g- 1 and pore volumes from 0.162 to 0.473 m3g-1, UV-Vis diffuse reflectance showed the redshift of the absorption edge and the bandgap decrease after post synthetic calcination of the materials presented. The TEM, FT-IR, DTA and TG measurements have been made to well characterize the materials synthesized. The mesoporous samples obtained were applied as anode materials for dye-sensitized solar cells and showed good activity in photon-to-current conversion process with efficiency values ranging from 0.54% to 4.6% and fill factors in the 52% to 67% range. The photovoltaic performances were not as high as those obtained for the materials synthesized by us earlier employing ethanol as a solvent. The differences in the electron lifetime, calculated from electrochemical impedance spectroscopy results and varying between 4.3 to 17.5 ms, were found as a main factor determining the efficiency of the investigated photovoltaic cells. PMID:27741313

Large-Scale, Three–Dimensional, Free–Standing, and Mesoporous Metal Oxide Networks for High–Performance Photocatalysis

PubMed Central

Bai, Hua; Li, Xinshi; Hu, Chao; Zhang, Xuan; Li, Junfang; Yan, Yan; Xi, Guangcheng

2013-01-01

Mesoporous nanostructures represent a unique class of photocatalysts with many applications, including splitting of water, degradation of organic contaminants, and reduction of carbon dioxide. In this work, we report a general Lewis acid catalytic template route for the high–yield producing single– and multi–component large–scale three–dimensional (3D) mesoporous metal oxide networks. The large-scale 3D mesoporous metal oxide networks possess large macroscopic scale (millimeter–sized) and mesoporous nanostructure with huge pore volume and large surface exposure area. This method also can be used for the synthesis of large–scale 3D macro/mesoporous hierarchical porous materials and noble metal nanoparticles loaded 3D mesoporous networks. Photocatalytic degradation of Azo dyes demonstrated that the large–scale 3D mesoporous metal oxide networks enable high photocatalytic activity. The present synthetic method can serve as the new design concept for functional 3D mesoporous nanomaterials. PMID:23857595

Development of a semigraphitic sulfur-doped ordered mesoporous carbon material for electroanalytical applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maluta, Jaqueline R.; Machado, Sergio A. S.; Chaudhary, Umesh

The modification of traditional electrodes with mesoporous carbons is a promising strategy to produce high performance electrodes for electrochemical sensing. The high surface area of mesoporous carbons provides a large number of electroactive sites for binding analytes. Controlling the pore size and structure of mesoporous carbons and modifying their electronic properties via doping offers additional benefits like maximizing transport and tuning the electrochemical processes associated with analyte detection. This work reports a facile method to produce sulfur-doped ordered mesoporous carbon materials (S-OMC) with uniform pore structure, large pore volume, high surface area and semigraphitic structure. The synthesis used thiophenol asmore » a single source of carbon and sulfur, and iron as a catalyst for low temperature carbonization. The S-OMC material was deposited on a glassy carbon electrode and used as a sensor with high sensitivity (11.7 A L mol-1) and selectivity for chloramphenicol detection in presence of other antibiotics. As a proof-of-concept, the sensor was applied to the direct analysis of the drug in reconstituted powdered milk and in commercial eye drops.« less

Development of a semigraphitic sulfur-doped ordered mesoporous carbon material for electroanalytical applications

DOE PAGES

Maluta, Jaqueline R.; Machado, Sergio A. S.; Chaudhary, Umesh; ...

2017-10-29

The modification of traditional electrodes with mesoporous carbons is a promising strategy to produce high performance electrodes for electrochemical sensing. The high surface area of mesoporous carbons provides a large number of electroactive sites for binding analytes. Controlling the pore size and structure of mesoporous carbons and modifying their electronic properties via doping offers additional benefits like maximizing transport and tuning the electrochemical processes associated with analyte detection. This work reports a facile method to produce sulfur-doped ordered mesoporous carbon materials (S-OMC) with uniform pore structure, large pore volume, high surface area and semigraphitic structure. The synthesis used thiophenol asmore » a single source of carbon and sulfur, and iron as a catalyst for low temperature carbonization. The S-OMC material was deposited on a glassy carbon electrode and used as a sensor with high sensitivity (11.7 A L mol-1) and selectivity for chloramphenicol detection in presence of other antibiotics. As a proof-of-concept, the sensor was applied to the direct analysis of the drug in reconstituted powdered milk and in commercial eye drops.« less

Mesoporous CdS via Network of Self-Assembled Nanocrystals: Synthesis, Characterization and Enhanced Photoconducting Property.

PubMed

Patra, Astam K; Banerjee, Biplab; Bhaumik, Asim

2018-01-01

Semiconduction nanoparticles are intensively studied due to their huge potential in optoelctronic applications. Here we report an efficient chemical route for hydrothermal synthesis of aggregated mesoporous cadmium sulfide (CdS) nanoparticles using supramolecular-assembly of ionic and water soluble sodium salicylate as the capping agent. The nanostructure, mesophase, optical property and photoconductivity of these mesoporous CdS materials have been characterized by using small and wide angle powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2-sorption, Raman analysis, Fourier transformed infrared (FT-IR), UV-Visible DSR spectroscopy, and photoconductivity measurement. Wide angle XRD pattern and high resolution TEM image analysis suggested that the particle size of the materials is within 10 nm and the nanoparticles are in well-crystallized cubic phase. Mesoporous CdS nanoparticles showed drastically enhanced photoelectrochemical response under visible light irradiation on entrapping a photosensitizer (dye) molecule in the interparticle spaces. Efficient synthesis strategy and the enhanced photo response in the mesoporous CdS material could facilitate the designing of other porous semiconductor oxide/sulfide and their applications in photon-to-electron conversion processes.

Adsorption of mycotoxins in beverages onto functionalized mesoporous silicas

USDA-ARS?s Scientific Manuscript database

Mycotoxins, natural toxins produced by fungi, are a global concern as contaminates of agricultural commodities. Exposure to these toxins can be reduced by the use of binding materials. Templated mesoporous silicas are promising materials with favorable adsorptive properties for dyes, ions, and toxin...

Functionalized mesoporous silica supported copper(II) and nickel(II) catalysts for liquid phase oxidation of olefins.

PubMed

Nandi, Mahasweta; Roy, Partha; Uyama, Hiroshi; Bhaumik, Asim

2011-12-14

Highly ordered 2D-hexagonal mesoporous silica has been functionalized with 3-aminopropyltriethoxysilane (3-APTES). This is followed by its condensation with a dialdehyde, 4-methyl-2,6-diformylphenol to produce an immobilized Schiff-base ligand (I). This material is separately treated with methanolic solution of copper(II) chloride and nickel(II) chloride to obtain copper and nickel anchored mesoporous materials, designated as Cu-AMM and Ni-AMM, respectively. The materials have been characterized by Fourier transform infrared (FT-IR) and UV-vis diffuse reflectance (DRS) spectroscopy, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), N(2) adsorption-desorption studies and (13)C CP MAS NMR spectroscopy. The metal-grafted mesoporous materials have been used as catalysts for the efficient and selective epoxidation of alkenes, viz. cyclohexene, trans-stilbene, styrene, α-methyl styrene, cyclooctene and norbornene to their corresponding epoxides in the presence of tert-butyl hydroperoxide (TBHP) as the oxidant under mild liquid phase conditions.

Polysaccharide-derived mesoporous materials (Starbon®) for sustainable separation of complex mixtures.

PubMed

Zuin, Vânia G; Budarin, Vitaliy L; De Bruyn, Mario; Shuttleworth, Peter S; Hunt, Andrew J; Pluciennik, Camille; Borisova, Aleksandra; Dodson, Jennifer; Parker, Helen L; Clark, James H

2017-09-21

The recovery and separation of high value and low volume extractives are a considerable challenge for the commercial realisation of zero-waste biorefineries. Using solid-phase extractions (SPE) based on sustainable sorbents is a promising method to enable efficient, green and selective separation of these complex extractive mixtures. Mesoporous carbonaceous solids derived from renewable polysaccharides are ideal stationary phases due to their tuneable functionality and surface structure. In this study, the structure-separation relationships of thirteen polysaccharide-derived mesoporous materials and two modified types as sorbents for ten naturally-occurring bioactive phenolic compounds were investigated. For the first time, a comprehensive statistical analysis of the key molecular and surface properties influencing the recovery of these species was carried out. The obtained results show the possibility of developing tailored materials for purification, separation or extraction, depending on the molecular composition of the analyte. The wide versatility and application span of these polysaccharide-derived mesoporous materials offer new sustainable and inexpensive alternatives to traditional silica-based stationary phases.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, Po-Wen

The dissertation begins with Chapter 1, which is a general introduction of the fundamental synthesis of mesoporous silica materials, the selective functionlization of mesoporous silica materials, and the synthesis of nanostructured porous materials via nanocasting. In Chapter 2, the thermo-responsive polymer coated mesoporous silica nanoparticles (MSN) was synthesized via surface-initated polymerization and exhibited unique partition activities in a biphasic solution with the thermally induced change. In Chapter 3, the monodispersed spherical MSN with different mesoporous structure (MCM-48) was developed and employed as a template for the synthesis of mesoporous carbon nanoparticles (MCN) via nanocasting. MCN was demonstrated for the deliverymore » of membrane impermeable chemical agents inside the cells. The cellular uptake efficiency and biocompabtibility of MCN with human cervical cancer cells were also investigated. In addition to the biocompabtibility of MCN, MCN was demonstrated to support Rh-Mn nanoparticles for catalytic reaction in Chapter 4. Owing to the unique mesoporosity, Rh-Mn nanoparticles can be well distributed inside the mesoporous structure and exhibited interesting catalytic performance on CO hydrogenation. In Chapter 5, the synthesis route of the aforementioned MCM-48 MSN was discussed and investigated in details and other metal oxide nanoparticles were also developed via nanocasting by using MCM-48 MSN as a template. At last, there is a general conclusion summarized in Chapter 6.« less

Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica.

PubMed

Ji, Yazhou; Caskey, Christopher; Richards, Ryan M

2015-07-09

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties of the materials were investigated. We used a one pot sol-gel approach to intercalate gold nano particles in the walls of mesoporous silica. To start with the synthesis, P123 was used as template to form micelles. Then TESPTS was used as a surface modification agent to intercalate gold nano particles. Following this process, TEOS was added in as a silica source which underwent a polymerization process in acid environment. After hydrothermal processing and calcination, the final product was acquired. Several techniques were utilized to characterize the porosity, morphology and structure of the gold intercalated mesoporous silica. The results showed a stable structure of mesoporous silica after gold intercalation. Through the oxidation of benzyl alcohol as a benchmark reaction, the GMS materials showed high selectivity and recyclability.

Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica

PubMed Central

Ji, Yazhou; Caskey, Christopher; Richards, Ryan M.

2015-01-01

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties of the materials were investigated. We used a one pot sol-gel approach to intercalate gold nano particles in the walls of mesoporous silica. To start with the synthesis, P123 was used as template to form micelles. Then TESPTS was used as a surface modification agent to intercalate gold nano particles. Following this process, TEOS was added in as a silica source which underwent a polymerization process in acid environment. After hydrothermal processing and calcination, the final product was acquired. Several techniques were utilized to characterize the porosity, morphology and structure of the gold intercalated mesoporous silica. The results showed a stable structure of mesoporous silica after gold intercalation. Through the oxidation of benzyl alcohol as a benchmark reaction, the GMS materials showed high selectivity and recyclability. PMID:26274058

Mesoporous Iron Sulfide for Highly Efficient Electrocatalytic Hydrogen Evolution

DOE PAGES

Miao, Ran; Dutta, Biswanath; Sahoo, Sanjubala; ...

2017-09-05

Here, we report a facile synthetic protocol to pre-pare mesoporous FeS 2 without the aid of hard template as an electrocatalyst for the hydrogen evolution reaction (HER). The mesoporous FeS 2 materials with high surface area were successfully prepared by a sol-gel method follow-ing a sulfurization treatment in an H 2S atmosphere. A re-markable HER catalytic performance was achieved with a low overpotential of 96 mV at a current density of 10 mA·cm 2 and a Tafel slope of 78 mV per decade under alka-line conditions (pH 13). These theoretical calculations indicate that the excellent catalytic activity of mesoporous FeSmore » 2 is attributed to the exposed (210) facets. The mesoporous FeS 2 material might be a promising alternative to the Pt-based electrocatalysts for water splitting.« less

Hollow-structured mesoporous materials: chemical synthesis, functionalization and applications.

PubMed

Li, Yongsheng; Shi, Jianlin

2014-05-28

Hollow-structured mesoporous materials (HMMs), as a kind of mesoporous material with unique morphology, have been of great interest in the past decade because of the subtle combination of the hollow architecture with the mesoporous nanostructure. Benefitting from the merits of low density, large void space, large specific surface area, and, especially, the good biocompatibility, HMMs present promising application prospects in various fields, such as adsorption and storage, confined catalysis when catalytically active species are incorporated in the core and/or shell, controlled drug release, targeted drug delivery, and simultaneous diagnosis and therapy of cancers when the surface and/or core of the HMMs are functionalized with functional ligands and/or nanoparticles, and so on. In this review, recent progress in the design, synthesis, functionalization, and applications of hollow mesoporous materials are discussed. Two main synthetic strategies, soft-templating and hard-templating routes, are broadly sorted and described in detail. Progress in the main application aspects of HMMs, such as adsorption and storage, catalysis, and biomedicine, are also discussed in detail in this article, in terms of the unique features of the combined large void space in the core and the mesoporous network in the shell. Functionalization of the core and pore/outer surfaces with functional organic groups and/or nanoparticles, and their performance, are summarized in this article. Finally, an outlook of their prospects and challenges in terms of their controlled synthesis and scaled application is presented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mesoporous Silica Molecular Sieve based Nanocarriers: Transpiring Drug Dissolution Research.

PubMed

Pattnaik, Satyanarayan; Pathak, Kamla

2017-01-01

Improvement of oral bioavailability through enhancement of dissolution for poorly soluble drugs has been a very promising approach. Recently, mesoporous silica based molecular sieves have demonstrated excellent properties to enhance the dissolution velocity of poorly water-soluble drugs. Current research in this area is focused on investigating the factors influencing the drug release from these carriers, the kinetics of drug release and manufacturing approaches to scale-up production for commercial manufacture. This comprehensive review provides an overview of different methods adopted for synthesis of mesoporous materials, influence of processing factors on properties of these materials and drug loading methods. The drug release kinetics from mesoporous silica systems, the manufacturability and stability of these formulations are reviewed. Finally, the safety and biocompatibility issues related to these silica based materials are discussed. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Generalised syntheses of ordered mesoporous oxides: the atrane route

NASA Astrophysics Data System (ADS)

Cabrera, Saúl; El Haskouri, Jamal; Guillem, Carmen; Latorre, Julio; Beltrán-Porter, Aurelio; Beltrán-Porter, Daniel; Marcos, M. Dolores; Amorós *, Pedro

2000-06-01

A new simple and versatile technique to obtain mesoporous oxides is presented. While implying surfactant-assisted formation of mesostructured intermediates, the original chemical contribution of this approach lies in the use of atrane complexes as precursors. Without prejudice to their inherent unstability in aqueous solution, the atranes show a marked inertness towards hydrolysis. Bringing kinetic factors into play, it becomes possible to control the processes involved in the formation of the surfactant-inorganic phase composite micelles, which constitute the elemental building blocks of the mesostructures. Independent of the starting compositional complexity, both the mesostructured intermediates and the final mesoporous materials are chemically homogeneous. The final ordered mesoporous materials are thermally stable and show unimodal porosity, as well as homogeneous microstructure and texture. Examples of materials synthesised on account of the versatility of this new method, including siliceous, non siliceous and mixed oxides, are presented and discussed.

Hierarchical Zeolites with Amine-Functionalized Mesoporous Domains for Carbon Dioxide Capture.

PubMed

Nguyen, Tien Hoa; Kim, Sungjune; Yoon, Minyoung; Bae, Tae-Hyun

2016-03-08

To prepare materials with high CO2 adsorption, a series of hierarchical LTA zeolites possessing various mesopore spaces that are decorated with alkylamines was designed and synthesized. The highest CO2 uptake capacity was achieved when (3-aminopropyl)trimethoxysilane (APTMS) was grafted onto the hierarchical LTA zeolite having the largest mesopores. Owing to the contributions of both alkylamine groups grafted onto the mesopore surfaces and active sites in the LTA zeolites, the amount of CO2 that can be taken up on these materials is much higher than for conventional aminosilicas such SBA-15 and MCM-41. Furthermore, the adsorbent shows good CO2 uptake capacity and recyclability in dynamic flow conditions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and structural characterization of ZnO-and CuO-NPs supported mesoporous silica materials (hexagonal SBA-15 and lamellar-SiO2)

NASA Astrophysics Data System (ADS)

El-Nahhal, Issa M.; Salem, Jamil K.; Tabasi, Nihal S.; Hempelmann, Rolf; Kodeh, Fawzi S.

2018-01-01

Two different mesoporous silica structures (hexagonal and lamellar) were synthesized via sol-gel method using a series of triblock copolymer (Pluronic) surfactants. L81, L61 & L31 surfactants form lamellar structure whereas P123 surfactant forms a hexagonal structure. CuO and ZnO nanoparticles (NPs) supported mesoporous silica were synthesized using impregnation method. The structural properties of these materials were investigated using several characterization techniques such as FTIR, XRD, SAXS, TEM and TGA. SAXS and TEM confirmed that the obtained mesoporous silica is based on the EO/PO ratio of Pluronic surfactants. They proved that the mesoporosity of silica is well maintained even after they loaded with metal oxide nanoparticles.

Electrorheological behavior of copper phthalocyanine-doped mesoporous TiO2 suspensions.

PubMed

Di, Kai; Zhu, Yihua; Yang, Xiaoling; Li, Chunzhong

2006-02-15

A type of anhydrous electrorheological (ER) material of copper phthalocyanine (CuPC)-doped mesoporous TiO2 was synthesized by in situ micelle-assisted incorporation CuPC during mesoporous TiO2 synthesis. TEM, XRD and the nitrogen adsorption-desorption isotherms demonstrated that the material had mesoporous structure and an anatase framework. The ER behavior of the suspensions of CuPC-doped mesoporous TiO2 in silicone oil with the different volume fractions was investigated under an applied electric field. It is found that the suspensions showed visible electrorheological behavior which were compared with that of pure TiO2. The dopants of CuPC molecules within the mesochannel of TiO2 mesoporous sieve improved the conductivity of the particles and produced a proper conductivity of approximately 10(-7) S m(-1). Dielectric spectra of the ER fluid were measured to examine the peak of epsilon'' should appear in the frequency range of 10(2)-10(5) Hz and have a large Deltaepsilon' in this frequency range. Therefore, the both properties may make a conjunct effect on electrorheological behavior.

Design and functionalization of photocatalytic systems within mesoporous silica.

PubMed

Qian, Xufang; Fuku, Kojirou; Kuwahara, Yasutaka; Kamegawa, Takashi; Mori, Kohsuke; Yamashita, Hiromi

2014-06-01

In the past decades, various photocatalysts such as TiO2, transition-metal-oxide moieties within cavities and frameworks, or metal complexes have attracted considerable attention in light-excited catalytic processes. Owing to high surface areas, transparency to UV and visible light as well as easily modified surfaces, mesoporous silica-based materials have been widely used as excellent hosts for designing efficient photocatalytic systems under the background of environmental remediation and solar-energy utilization. This Minireview mainly focuses on the surface-chemistry engineering of TiO2/mesoporous silica photocatalytic systems and fabrication of binary oxides and nanocatalysts in mesoporous single-site-photocatalyst frameworks. Recently, metallic nanostructures with localized surface plasmon resonance (LSPR) have been widely studied in catalytic applications harvesting light irradiation. Accordingly, silver and gold nanostructures confined in mesoporous silica and their corresponding catalytic activity enhanced by the LSPR effect will be introduced. In addition, the integration of metal complexes within mesoporous silica materials for the construction of functional inorganic-organic supramolecular photocatalysts will be briefly described. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

SBA-15 Mesoporous Silica as Catalytic Support for Hydrodesulfurization Catalysts—Review

PubMed Central

Huirache-Acuña, Rafael; Nava, Rufino; Peza-Ledesma, Carmen L.; Lara-Romero, Javier; Alonso-Núñez, Gabriel; Pawelec, Barbara; Rivera-Muñoz, Eric M.

2013-01-01

SBA-15 is an interesting mesoporous silica material having highly ordered nanopores and a large surface area, which is widely employed as catalyst supports, absorbents, drug delivery materials, etc. Since it has a lack of functionality, heteroatoms and organic functional groups have been incorporated by direct or post-synthesis methods in order to modify their functionality. The aim of this article is to review the state-of-the-art related to the use of SBA-15-based mesoporous systems as supports for hydrodesulfurization (HDS) catalysts. PMID:28788323

Facile and cost effective synthesis of mesoporous spinel NiCo2O4 as an anode for high lithium storage capacity

NASA Astrophysics Data System (ADS)

Jadhav, Harsharaj S.; Kalubarme, Ramchandra S.; Park, Choong-Nyeon; Kim, Jaekook; Park, Chan-Jin

2014-08-01

To fulfill the high power and high energy density demands for Li-ion batteries (LIBs) new anode materials need to be explored to replace conventional graphite. Herein, we report the urea assisted facile co-precipitation synthesis of spinel NiCo2O4 and its application as an anode material for LIBs. The synthesized NiCo2O4 exhibited an urchin-like microstructure and polycrystalline and mesoporous nature. In addition, the mesoporous NiCo2O4 electrode exhibited an initial discharge capacity of 1095 mA h g-1 and maintained a reversible capacity of 1000 mA h g-1 for 400 cycles at 0.5 C-rate. The reversible capacity of NiCo2O4 could still be maintained at 718 mA h g-1, even at 10 C. The mesoporous NiCo2O4 exhibits great potential as an anode material for LIBs with the advantages of unique performance and facile preparation.To fulfill the high power and high energy density demands for Li-ion batteries (LIBs) new anode materials need to be explored to replace conventional graphite. Herein, we report the urea assisted facile co-precipitation synthesis of spinel NiCo2O4 and its application as an anode material for LIBs. The synthesized NiCo2O4 exhibited an urchin-like microstructure and polycrystalline and mesoporous nature. In addition, the mesoporous NiCo2O4 electrode exhibited an initial discharge capacity of 1095 mA h g-1 and maintained a reversible capacity of 1000 mA h g-1 for 400 cycles at 0.5 C-rate. The reversible capacity of NiCo2O4 could still be maintained at 718 mA h g-1, even at 10 C. The mesoporous NiCo2O4 exhibits great potential as an anode material for LIBs with the advantages of unique performance and facile preparation. Electronic supplementary information (ESI) available: Experimental details and additional experimental results. See DOI: 10.1039/c4nr02183e

Comparative study of hydrogen storage on metal doped mesoporous materials

NASA Astrophysics Data System (ADS)

Carraro, P. M.; Sapag, K.; Oliva, M. I.; Eimer, G. A.

2018-06-01

The hydrogen adsorption capacity of mesoporous materials MCM-41 modified with Co, Fe, Ti, Mg and Ni at 77 K and 10 bar was investigated. Various techniques including XRD, N2 adsorption and DRUV-vis were employed for the materials characterization. The results showed that a low nickel loading on MCM-41 support promoted the presence of hydrogen-favorable sites, increasing the hydrogen storage capacity.

Synthesis of 5-hydroxymethylfurural from carbohydrates using large-pore mesoporous tin phosphate.

PubMed

Dutta, Arghya; Gupta, Dinesh; Patra, Astam K; Saha, Basudeb; Bhaumik, Asim

2014-03-01

A large-pore mesoporous tin phosphate (LPSnP-1) material has been synthesized hydrothermally by using Pluronic P123 as the structure-directing agent. The material is composed of aggregated nanoparticles of 10-15 nm in diameter and has a BET surface area of 216 m(2)  g(-1) with an average pore diameter of 10.4 nm. This pore diameter is twice as large as that of mesoporous tin phosphate materials synthesized through the surfactant-templating pathways reported previously. LPSnP-1 shows excellent catalytic activity for the conversion of fructose, glucose, sucrose, cellobiose, and cellulose to 5-hydroxymethylfurfural (HMF) in a water/methyl isobutyl ketone biphasic solvent to give maximum yields of HMF of 77, 50, 51, 39, and 32 mol %, respectively, under microwave-assisted heating at 423 K. Under comparable reaction conditions, LPSnP-1 gives 12 % more HMF yield than a small-pore mesoporous tin phosphate catalyst that has an identical framework composition. This confirms the beneficial role of large mesopores and nanoscale particle morphology in catalytic reactions that involve bulky natural carbohydrate molecules. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of Mesoporous Single Crystal Co(OH)2 Nanoplate and Its Topotactic Conversion to Dual-Pore Mesoporous Single Crystal Co3O4.

PubMed

Jia, Bao-Rui; Qin, Ming-Li; Li, Shu-Mei; Zhang, Zi-Li; Lu, Hui-Feng; Chen, Peng-Qi; Wu, Hao-Yang; Lu, Xin; Zhang, Lin; Qu, Xuan-Hui

2016-06-22

A new class of mesoporous single crystalline (MSC) material, Co(OH)2 nanoplates, is synthesized by a soft template method, and it is topotactically converted to dual-pore MSC Co3O4. Most mesoporous materials derived from the soft template method are reported to be amorphous or polycrystallined; however, in our synthesis, Co(OH)2 seeds grow to form single crystals, with amphiphilic block copolymer F127 colloids as the pore producer. The single-crystalline nature of material can be kept during the conversion from Co(OH)2 to Co3O4, and special dual-pore MSC Co3O4 nanoplates can be obtained. As the anode of lithium-ion batteries, such dual-pore MSC Co3O4 nanoplates possess exceedingly high capacity as well as long cyclic performance (730 mAh g(-1) at 1 A g(-1) after the 350th cycle). The superior performance is because of the unique hierarchical mesoporous structure, which could significantly improve Li(+) diffusion kinetics, and the exposed highly active (111) crystal planes are in favor of the conversion reaction in the charge/discharge cycles.

Imprint-coating synthesis of selective functionalized ordered mesoporous sorbents for separation and sensors

DOEpatents

Dai, Sheng; Burleigh, Mark C.; Shin, Yongsoon

2001-01-01

The present invention relates generally to mesoporous sorbent materials having high capacity, high selectivity, fast kinetics, and molecular recognition capability. The invention also relates to a process for preparing these mesoporous substrates through molecular imprinting techniques which differ from convention techniques in that a template molecule is bound to one end of bifunctional ligands to form a complex prior to binding of the bifunctional ligands to the substrate. The present invention also relates to methods of using the mesoporous sorbent materials, for example, in the separation of toxic metals from process effluents, paints, and other samples; detection of target molecules, such as amino acids, drugs, herbicides, fertilizers, and TNT, in samples; separation and/or detection of substances using chromatography; imaging agents; sensors; coatings; and composites.

Calcium-silicate mesoporous nanoparticles loaded with chlorhexidine for both anti- Enterococcus faecalis and mineralization properties.

PubMed

Fan, Wei; Li, Yanyun; Sun, Qing; Ma, Tengjiao; Fan, Bing

2016-10-21

In infected periapical tissues, Enterococcus faecalis is one of the most common dominant bacteria. Chlorhexidine has been proved to show strong antibacterial ability against E. faecalis but is ineffective in promoting mineralization for tissues around root apex. Mesoporous calcium-silicate nanoparticles are newly synthesized biomaterials with excellent ability to promote mineralization and carry-release bioactive molecules in a controlled manner. In this study, mesoporous calcium-silicate nanoparticles were functionalized with chlorhexidine and their releasing profile, antibacterial ability, effect on cell proliferation and in vitro mineralization property were evaluated. The chlorhexidine was successfully incorporated into mesoporous calcium-silicate nanoparticles by a mixing-coupling method. The new material could release chlorhexidine as well as Ca 2+ and SiO 3 2- in a sustained manner with an alkaline pH value under different conditions. The antimicrobial ability against planktonic E. faecalis was dramatically improved after chlorhexidine incorporation. The nanoparticles with chlorhexidine showed no negative effect on cell proliferation with low concentrations. On dentin slices, the new synthesized material demonstrated a similar inhibitory effect on E. faecalis as the chlorhexidine. After being immersed in SBF for 9 days, numerous apatite crystals could be observed on surfaces of the material tablets. Mesoporous calcium-silicate nanoparticles loaded with chlorhexidine exhibited release of ions and chlorhexidine, low cytotoxicity, excellent antibacterial ability and in vitro mineralization. This material could be developed into a new effective intra-canal medication in dentistry or a new bone defect filling material for infected bone defects.

Low-Temperature Fluorination of Soft-Templated Mesoporous Carbons for a High-Power Lithium/Carbon Fluoride Battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fulvio, Pasquale F; Dai, Sheng; Guo, Bingkun

Soft-templated mesoporous carbons and activated mesoporous carbons were fluorinated using elemental fluorine between room temperature and 235 C. The mesoporous carbons were prepared via self-assembly synthesis of phloroglucinol formaldehyde as a carbon precursor in the presence of triblock ethylene oxide propylene oxide ethylene oxide copolymer BASF Pluronic F127 as the template. The F/C ratios ranged from 0.15 to 0.75 according to gravimetric, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy analysis. Materials have mesopore diameters up to 11 nm and specific surface areas as high as 850 m2 g 1 after fluorination as calculated from nitrogen adsorption isotherms at 196more » C. Furthermore, the materials exhibit higher discharge potentials and energy and power densities as well as faster reaction kinetics under high current densities than commercial carbon fluorides with similar fluorine contents when tested as cathodes for Li/CFx batteries.« less

Mesoporous Transition Metal Oxides for Supercapacitors.

PubMed

Wang, Yan; Guo, Jin; Wang, Tingfeng; Shao, Junfeng; Wang, Dong; Yang, Ying-Wei

2015-10-14

Recently, transition metal oxides, such as ruthenium oxide (RuO₂), manganese dioxide (MnO₂), nickel oxides (NiO) and cobalt oxide (Co₃O₄), have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are resulted from the effective contacts between electrode materials and electrolytes as well as fast transportation of ions and electrons in the bulk of electrode and at the interface of electrode and electrolyte. During the past decade, many achievements on mesoporous transition metal oxides have been made. In this mini-review, we select several typical nanomaterials, such as RuO₂, MnO₂, NiO, Co₃O₄ and nickel cobaltite (NiCo₂O₄), and briefly summarize the recent research progress of these mesoporous transition metal oxides-based electrodes in the field of supercapacitors.

Mesoporous Transition Metal Oxides for Supercapacitors

PubMed Central

Wang, Yan; Guo, Jin; Wang, Tingfeng; Shao, Junfeng; Wang, Dong; Yang, Ying-Wei

2015-01-01

Recently, transition metal oxides, such as ruthenium oxide (RuO2), manganese dioxide (MnO2), nickel oxides (NiO) and cobalt oxide (Co3O4), have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are resulted from the effective contacts between electrode materials and electrolytes as well as fast transportation of ions and electrons in the bulk of electrode and at the interface of electrode and electrolyte. During the past decade, many achievements on mesoporous transition metal oxides have been made. In this mini-review, we select several typical nanomaterials, such as RuO2, MnO2, NiO, Co3O4 and nickel cobaltite (NiCo2O4), and briefly summarize the recent research progress of these mesoporous transition metal oxides-based electrodes in the field of supercapacitors. PMID:28347088

Mesopore quality determines the lifetime of hierarchically structured zeolite catalysts

NASA Astrophysics Data System (ADS)

Milina, Maria; Mitchell, Sharon; Crivelli, Paolo; Cooke, David; Pérez-Ramírez, Javier

2014-05-01

Deactivation due to coking limits the lifetime of zeolite catalysts in the production of chemicals and fuels. Superior performance can be achieved through hierarchically structuring the zeolite porosity, yet no relation has been established between the mesopore architecture and the catalyst lifetime. Here we introduce a top-down demetallation strategy to locate mesopores in different regions of MFI-type crystals with identical bulk porous and acidic properties. In contrast, well-established bottom-up strategies as carbon templating and seed silanization fail to yield materials with matching characteristics. Advanced characterization tools capable of accurately discriminating the mesopore size, distribution and connectivity are applied to corroborate the concept of mesopore quality. Positron annihilation lifetime spectroscopy proves powerful to quantify the global connectivity of the intracrystalline pore network, which, as demonstrated in the conversions of methanol or of propanal to hydrocarbons, is closely linked to the lifetime of zeolite catalysts. The findings emphasize the need to aptly tailor hierarchical materials for maximal catalytic advantage.

Supercapacitors based on ordered mesoporous carbon derived from furfuryl alcohol: effect of the carbonized temperature.

PubMed

Li, Na; Xu, Jianxiong; Chen, Han; Wang, Xianyou

2014-07-01

Supercapacitors are successfully prepared from ordered mesoporous carbon (OMC) synthesized by employing the mesoporous silica, SBA-15 as template and furfuryl alcohol as carbon source. It is found that the carbonized temperature greatly influences the physical properties of the synthesized mesoporous carbon materials. The optimal carbonized temperature is measured to be 600 degrees C under which OMC with the specific surface area of 1219 m2/g and pore volume of 1.31 cm3/g and average pore diameter of - 3 nm are synthesized. The OMC materials synthesized under different carbonized temperature are used as electrode material of supercapacitors and the electrochemical properties of the OMC materials are compared by using cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic charge-discharge and self-discharge tests. The results show that the electrochemical properties of the OMC materials are directly related to the specific surface area and pore volume of the mesoporous carbon and the electrode prepared from the OMC synthesized under the carbonized temperature of 600 degrees C (OMC-600) exhibits the most excellent electrochemical performance with the specific capacitance of 207.08 F/g obtained from cyclic voltammetry at the scan rate of 1 mV/s, small resistance and low self-discharge rate. Moreover, the supercapacitor based on the OMC-600 material exhibits good capacitance properties and stable cycle behavior with the specific capacitance of 105 F/g at the current density of 700 mA/g, and keeps a specific capacitance of 98 F/g after 20000 consecutive charge/discharge cycles.

Preparation of hollow mesoporous carbon spheres and their performances for electrochemical applications

NASA Astrophysics Data System (ADS)

Ariyanto, T.; Zhang, G. R.; Kern, A.; Etzold, B. J. M.

2018-03-01

Hollow carbon materials have received intensive attention for energy storage/conversion applications due to their attractive properties of high conductivity, high surface area, large void and short diffusion pathway. In this work, a novel hollow mesoporous material based on carbide-derived carbon (CDC) is presented. CDC is a new class of carbon material synthesized by the selective extraction of metals from metal carbides. With a two-stage extraction procedure of carbides with chlorine, firstly hybrid core-shell carbon particles were synthesized, i.e. mesoporous/graphitic carbon shells covering microporous/amorphous carbon cores. The amorphous cores were then selectively removed from particles by a careful oxidative treatment utilizing its low thermal characters while the more stable carbon shells remained, thus resulting hollow particles. The characterization methods (e.g. N2 sorption, Raman spectroscopy, temperature-programmed oxidation and SEM) proved the successful synthesis of the aspired material. In electric double-layer capacitor (EDLC) testing, this novel hollow core material showed a remarkable enhancement of EDLC’s rate handling ability (75% at a high scan rate) with respect to an entirely solid-mesoporous material. Furthermore, as a fuel cell catalyst support the material showed higher Pt mass activity (a factor of 1.8) compared to a conventional carbon support for methanol oxidation without noticeably decreasing activity in a long-term testing. Therefore, this carbon nanostructure shows great promises as efficient electrode materials for energy storage and conversion systems.

Facile Synthesis of A 3D Flower-Like Mesoporous Ni@C Composite Material for High-Energy Aqueous Asymmetric Supercapacitors.

PubMed

Liu, Song; An, Cuihua; Zang, Lei; Chang, Xiaoya; Guo, Huinan; Jiao, Lifang; Wang, Yijing

2018-04-16

A 3D flower-like mesoporous Ni@C composite material has been synthesized by using a facile and economical one-pot hydrothermal method. This unique 3D flower-like Ni@C composite, which exhibited a high surface area (522.4 m 2  g -1 ), consisted of highly dispersed Ni nanoparticles on mesoporous carbon flakes. The effect of calcination temperature on the electrochemical performance of the Ni@C composite was systematically investigated. The optimized material (Ni@C 700) displayed high specific capacity (1306 F g -1 at 2 A g -1 ) and excellent cycling performance (96.7 % retention after 5000 cycles). Furthermore, an asymmetric supercapacitor (ASC) that contained Ni@C 700 as cathode and mesoporous carbon (MC) as anode demonstrated high energy density (60.4 W h kg -1 at a power density of 750 W kg -1 ). © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetic ordered mesoporous Fe3O4/CeO2 composites with synergy of adsorption and Fenton catalysis

NASA Astrophysics Data System (ADS)

Li, Keyan; Zhao, Yongqin; Song, Chunshan; Guo, Xinwen

2017-12-01

Magnetic Fe3O4/CeO2 composites with highly ordered mesoporous structure and large surface area were synthesized by impregnation-calcination method, and the mesoporous CeO2 as support was synthesized via the hard template approach. The composition, morphology and physicochemical properties of the materials were characterized by XRD, SEM, TEM, XPS, Raman spectra and N2 adsorption/desorption analysis. The mesoporous Fe3O4/CeO2 composite played a dual-function role as both adsorbent and Fenton-like catalyst for removal of organic dye. The methylene blue (MB) removal efficiency of mesoporous Fe3O4/CeO2 was much higher than that of irregular porous Fe3O4/CeO2. The superior adsorption ability of mesoporous materials was attributed to the abundant oxygen vacancies on the surface of CeO2, high surface area and ordered mesoporous channels. The good oxidative degradation resulted from high Ce3+ content and the synergistic effect between Fe and Ce. The mesoporous Fe3O4/CeO2 composite presented low metal leaching (iron 0.22 mg L-1 and cerium 0.63 mg L-1), which could be ascribed to the strong metal-support interactions for dispersion and stabilization of Fe species. In addition, the composite can be easily separated from reaction solution with an external magnetic field due to its magnetic property, which is important to its practical applications.

Hierarchical micro- and mesoporous carbide-derived carbon as a high-performance electrode material in supercapacitors.

PubMed

Rose, Marcus; Korenblit, Yair; Kockrick, Emanuel; Borchardt, Lars; Oschatz, Martin; Kaskel, Stefan; Yushin, Gleb

2011-04-18

Ordered mesoporous carbide-derived carbon (OM-CDC) materials produced by nanocasting of ordered mesoporous silica templates are characterized by a bimodal pore size distribution with a high ratio of micropores. The micropores result in outstanding adsorption capacities and the well-defined mesopores facilitate enhanced kinetics in adsorption processes. Here, for the first time, a systematic study is presented, in which the effects of synthesis temperature on the electrochemical performance of these materials in supercapacitors based on a 1 M aqueous solution of sulfuric acid and 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid are reported. Cyclic voltammetry shows the specific capacitance of the OM-CDC materials exceeds 200 F g(-1) in the aqueous electrolyte and 185 F g(-1) in the ionic liquid, when measured in a symmetric configuration in voltage ranges of up to 0.6 and 2 V, respectively. The ordered mesoporous channels in the produced OM-CDC materials serve as ion-highways and allow for very fast ionic transport into the bulk of the OM-CDC particles. At room temperature the enhanced ion transport leads to 75% and 90% of the capacitance retention at current densities in excess of ∼10 A g(-1) in ionic liquid and aqueous electrolytes, respectively. The supercapacitors based on 250-300 μm OM-CDC electrodes demonstrate an operating frequency of up to 7 Hz in aqueous electrolyte. The combination of high specific capacitance and outstanding rate capabilities of the OM-CDC materials is unmatched by state-of-the art activated carbons and strictly microporous CDC materials. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Validity of the t-plot method to assess microporosity in hierarchical micro/mesoporous materials.

PubMed

Galarneau, Anne; Villemot, François; Rodriguez, Jeremy; Fajula, François; Coasne, Benoit

2014-11-11

The t-plot method is a well-known technique which allows determining the micro- and/or mesoporous volumes and the specific surface area of a sample by comparison with a reference adsorption isotherm of a nonporous material having the same surface chemistry. In this paper, the validity of the t-plot method is discussed in the case of hierarchical porous materials exhibiting both micro- and mesoporosities. Different hierarchical zeolites with MCM-41 type ordered mesoporosity are prepared using pseudomorphic transformation. For comparison, we also consider simple mechanical mixtures of microporous and mesoporous materials. We first show an intrinsic failure of the t-plot method; this method does not describe the fact that, for a given surface chemistry and pressure, the thickness of the film adsorbed in micropores or small mesopores (< 10σ, σ being the diameter of the adsorbate) increases with decreasing the pore size (curvature effect). We further show that such an effect, which arises from the fact that the surface area and, hence, the free energy of the curved gas/liquid interface decreases with increasing the film thickness, is captured using the simple thermodynamical model by Derjaguin. The effect of such a drawback on the ability of the t-plot method to estimate the micro- and mesoporous volumes of hierarchical samples is then discussed, and an abacus is given to correct the underestimated microporous volume by the t-plot method.

Ordered mesoporous polymer-silica hybrid nanoparticles as vehicles for the intracellular controlled release of macromolecules.

PubMed

Kim, Tae-Wan; Slowing, Igor I; Chung, Po-Wen; Lin, Victor Shang-Yi

2011-01-25

A two-dimensional hexagonal ordered mesoporous polymer-silica hybrid nanoparticle (PSN) material was synthesized by polymerization of acrylate monomers on the surface of SBA-15 mesoporous silica nanoparticles. The structure of the PSN material was analyzed using a series of different techniques, including transmission electron microscopy, powder X-ray diffraction, and N(2) sorption analysis. These structurally ordered mesoporous polymer-silica hybrid nanoparticles were used for the controlled release of membrane-impermeable macromolecules inside eukaryotic cells. The cellular uptake efficiency and biocompatibility of PSN with human cervical cancer cells (HeLa) were investigated. Our results show that the inhibitory concentration (IC(50)) of PSN is very high (>100 μg/mL per million cells), while the median effective concentration for the uptake (EC(50)) of PSN is low (EC(50) = 4.4 μg/mL), indicating that PSNs are fairly biocompatible and easily up-taken in vitro. A membrane-impermeable macromolecule, 40 kDa FITC-Dextran, was loaded into the mesopores of PSNs at low pH. We demonstrated that the PSN material could indeed serve as a transmembrane carrier for the controlled release of FITC-Dextran at the pH level inside live HeLa cells. We believe that further developments of this PSN material will lead to a new generation of nanodevices for intracellular controlled delivery applications.

Large pore mesoporous silica nanomaterials for application in delivery of biomolecules

NASA Astrophysics Data System (ADS)

Knežević, Nikola Ž.; Durand, Jean-Olivier

2015-01-01

Various approaches for the synthesis of mesoporous silicate nanoparticles (MSN) with large pore (LP) diameters (in the range of 3-50 nm) are reviewed in this article. The work also covers the construction of magnetic analogues of large pore-mesoporous silica nanoparticles (LPMMSN) and their biomedical applications. The constructed materials exhibit vast potential for application in the loading and delivery of large drug molecules and biomolecules. Literature reports on the application of LPMSN and LPMMSN materials for the adsorption and delivery of proteins, enzymes, antibodies, and nucleic acids are covered in depth, which exemplify their highly potent characteristics for use in drug and biomolecule delivery to diseased tissues.Various approaches for the synthesis of mesoporous silicate nanoparticles (MSN) with large pore (LP) diameters (in the range of 3-50 nm) are reviewed in this article. The work also covers the construction of magnetic analogues of large pore-mesoporous silica nanoparticles (LPMMSN) and their biomedical applications. The constructed materials exhibit vast potential for application in the loading and delivery of large drug molecules and biomolecules. Literature reports on the application of LPMSN and LPMMSN materials for the adsorption and delivery of proteins, enzymes, antibodies, and nucleic acids are covered in depth, which exemplify their highly potent characteristics for use in drug and biomolecule delivery to diseased tissues. Dedicated to Professor Jeffrey I. Zink on the occasion of his 70th birthday.

Importance of Micropore-Mesopore Interfaces in Carbon Dioxide Capture by Carbon-Based Materials.

PubMed

Durá, Gema; Budarin, Vitaliy L; Castro-Osma, José A; Shuttleworth, Peter S; Quek, Sophie C Z; Clark, James H; North, Michael

2016-08-01

Mesoporous carbonaceous materials (Starbons®) derived from low-value/waste bio-resources separate CO2 from CO2 /N2 mixtures. Compared to Norit activated charcoal (AC), Starbons® have much lower microporosities (8-32 % versus 73 %) yet adsorb up to 65 % more CO2 . The presence of interconnected micropores and mesopores is responsible for the enhanced CO2 adsorption. The Starbons® also showed three-four times higher selectivity for CO2 adsorption rather than N2 adsorption compared to AC. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ionic liquid-templated preparation of mesoporous silica embedded with nanocrystalline sulfated zirconia

NASA Astrophysics Data System (ADS)

Ward, Antony J.; Pujari, Ajit A.; Costanzo, Lorenzo; Masters, Anthony F.; Maschmeyer, Thomas

2011-12-01

A series of mesoporous silicas impregnated with nanocrystalline sulphated zirconia was prepared by a sol-gel process using an ionic liquid-templated route. The physicochemical properties of the mesoporous sulphated zirconia materials were studied using characterisation techniques such as inductively coupled optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray microanalysis, elemental analysis and X-ray photoelectron spectroscopy. Analysis of the new silicas indicates isomorphous substitution of silicon with zirconium and reveals the presence of extremely small (< 10 nm) polydispersed zirconia nanoparticles in the materials with zirconium loadings from 27.77 to 41.4 wt.%.

Magnetic spherical cores partly coated with periodic mesoporous organosilica single crystals.

PubMed

Li, Jing; Wei, Yong; Li, Wei; Deng, Yonghui; Zhao, Dongyuan

2012-03-07

Core-shell structured materials are of special significance in various applications. Until now, most reported core-shell structures have polycrystalline or amorphous coatings as their shell layers, with popular morphologies of microspheres or quasi-spheres. However, the single crystals, either mesoscale or atomic ones, are still rarely reported as shell layers. If single crystals can be coated on core materials, it would result in a range of new type core-shell structures with various morphologies, and probably more potential applications. In this work, we demonstrate that periodic mesoporous organosilica (PMO) single crystals can partly grow on magnetic microspheres to form incomplete Fe(3)O(4)@nSiO(2)@PMO core-shell materials in aqueous solution, which indeed is the first illustration that mesoporous single-crystal materials can be used as shell layers for preparation of core-shell materials. The achieved materials have advantages of high specific surface areas, good magnetic responses, embedded functional groups and cubic mesopore channels, which might provide them with various application conveniences. We suppose the partial growth is largely decided by the competition between growing tendency of single crystals and the resistances to this tendency. In principle, other single crystals, including a range of atomic single crystals, such as zeolites, are able to be developed into such core-shell structures.

Mesoporous Silica Chips for Selective Enrichment and Stabilization of Low Molecular Weight Proteome

PubMed Central

Bouamrani, Ali; Hu, Ye; Tasciotti, Ennio; Li, Li; Chiappini, Ciro; Liu, Xuewu; Ferrari, Mauro

2010-01-01

The advanced properties of mesoporous silica have been demonstrated in applications which include chemical sensing, filtration, catalysis, drug-delivery and selective biomolecular uptake. These properties depend on the architectural, physical and chemical properties of the material, which in turn are determined by the processing parameters in evaporation-induced self-assembly. In this study, we introduce a combinatorial approach for the removal of the high molecular weight proteins and for the specific isolation and enrichment of low molecular weight species. This approach is based on Mesoporous Silica Chips able to fractionate, selectively harvest and protect from enzymatic degradation, peptides and proteins present in complex human biological fluids. We present the characterization of the harvesting properties of a wide range of mesoporous chips using a library of peptides and proteins standard and their selectivity on the recovery of serum peptidome. Using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, we established the correlation between the harvesting specificity and the physico-chemical properties of mesoporous silica surfaces. The introduction of this mesoporous material with fine controlled properties will provide a powerful platform for proteomics application offering a rapid and efficient methodology for low molecular weight biomarker discovery. PMID:20013801

Mesoporous silica chips for selective enrichment and stabilization of low molecular weight proteome.

PubMed

Bouamrani, Ali; Hu, Ye; Tasciotti, Ennio; Li, Li; Chiappini, Ciro; Liu, Xuewu; Ferrari, Mauro

2010-02-01

The advanced properties of mesoporous silica have been demonstrated in applications, which include chemical sensing, filtration, catalysis, drug delivery and selective biomolecular uptake. These properties depend on the architectural, physical and chemical properties of the material, which in turn are determined by the processing parameters in evaporation-induced self-assembly. In this study, we introduce a combinatorial approach for the removal of the high molecular weight proteins and for the specific isolation and enrichment of low molecular weight species. This approach is based on mesoporous silica chips able to fractionate, selectively harvest and protect from enzymatic degradation, peptides and proteins present in complex human biological fluids. We present the characterization of the harvesting properties of a wide range of mesoporous chips using a library of peptides and proteins standard and their selectivity on the recovery of serum peptidome. Using MALDI-TOF-MS, we established the correlation between the harvesting specificity and the physicochemical properties of mesoporous silica surfaces. The introduction of this mesoporous material with fine controlled properties will provide a powerful platform for proteomics application offering a rapid and efficient methodology for low molecular weight biomarker discovery.

Direct synthesis of Ti-containing SBA-16-type mesoporous material by the evaporation-induced self-assembly method and its catalytic performance for oxidative desulfurization.

PubMed

Shah, Asma Tufail; Li, Baoshan; Abdalla, Zaki Eldin Ali

2009-08-15

A novel Ti-containing SBA-16-type mesoporous material (with various Ti loadings of 5, 10, and 15 wt%) was synthesized by an evaporation-induced self-assembly method using F127 copolymer as template. The materials were characterized by XRD, FTIR, TG-DTA, N(2) adsorption, SEM, HRTEM, and XPS. The characterization results show that the material possesses high thermal stability, thick pore walls (10.43-10.68 nm), and high surface area (642.26-691.5 m(2)/g) with a mesoporous worm-like structure, and titanium was successfully incorporated into the silica matrix with a tetrahedral environment. The material showed high activity in the oxidative desulfurization of DBT and its activity was not reduced even after three times recycling; further reuse resulted in a gradual decrease in its activity.

Functionalized bimodal mesoporous silicas as carriers for controlled aspirin delivery

NASA Astrophysics Data System (ADS)

Gao, Lin; Sun, Jihong; Li, Yuzhen

2011-08-01

The bimodal mesoporous silica modified with 3-aminopropyltriethoxysilane was performed as the aspirin carrier. The samples' structure, drug loading and release profiles were characterized with X-ray diffraction, scanning electron microscopy, N 2 adsorption and desorption, Fourier transform infrared spectroscopy, TG analysis, elemental analysis and UV-spectrophotometer. For further exploring the effects of the bimodal mesopores on the drug delivery behavior, the unimodal mesoporous material MCM-41 was also modified as the aspirin carrier. Meantime, Korsmeyer-Peppas equation ft= ktn was employed to analyze the dissolution data in details. It is indicated that the bimodal mesopores are beneficial for unrestricted drug molecules diffusing and therefore lead to a higher loading and faster releasing than that of MCM-41. The results show that the aspirin delivery properties are influenced considerably by the mesoporous matrix, whereas the large pore of bimodal mesoporous silica is the key point for the improved controlled-release properties.

Mesoporous carbons and polymers

DOEpatents

Bell, William; Dietz, Steven

2001-01-01

A mesoporous material prepared by polymerizing a resorcinol/formaldehyde system from an aqueous solution containing resorcinol, formaldehyde and a surfactant and optionally pyrolyzing the polymer to form a primarily carbonaceous solid. The material has an average pore size between 4 and 75 nm and is suitable for use in liquid-phase surface limited applications, including sorbent, catalytic, and electrical applications.

Synthesis of non-siliceous mesoporous oxides.

PubMed

Gu, Dong; Schüth, Ferdi

2014-01-07

Mesoporous non-siliceous oxides have attracted great interest due to their unique properties and potential applications. Since the discovery of mesoporous silicates in 1990s, organic-inorganic assembly processes by using surfactants or block copolymers as soft templates have been considered as a feasible path for creating mesopores in metal oxides. However, the harsh sol-gel conditions and low thermal stabilities have limited the expansion of this method to various metal oxide species. Nanocasting, using ordered mesoporous silica or carbon as a hard template, has provided possibilities for preparing novel mesoporous materials with new structures, compositions and high thermal stabilities. This review concerns the synthesis, composition, and parameter control of mesoporous non-siliceous oxides. Four synthesis routes, i.e. soft-templating (surfactants or block copolymers as templates), hard-templating (mesoporous silicas or carbons as sacrificial templates), colloidal crystal templating (3-D ordered colloidal particles as a template), and super lattice routes, are summarized in this review. Mesoporous metal oxides with different compositions have different properties. Non-siliceous mesoporous oxides are comprehensively described, including a discussion of constituting elements, synthesis, and structures. General aspects concerning pore size control, atomic scale crystallinity, and phase control are also reviewed.

A Review on the Synthesis and Applications of Mesostructured Transition Metal Phosphates

PubMed Central

Lin, Ronghe; Ding, Yunjie

2013-01-01

Considerable efforts have been devoted to extending the range of the elemental composition of mesoporous materials since the pioneering work of the M41S family of ordered mesoporous silica by Mobil researchers. The synthesis of transition metal-containing mesostructured materials with large surface area and high porosity has drawn great attention for its potential applications in acid and redox catalysis, photocatalysis, proton conducting devices, environmental restoration and so on. Thus, various transition metals-containing mesoporous materials, including transition metal-substituted mesoporous silicates, mesostructured transition metal oxides and transition metal phosphates (TMP), have been documented in the literature. Among these, mesostructured TMP materials are less studied, but possess some unique features, partly because of the easy and facile functionalization of PO4 and/or P–OH groups, rendering them interesting functional materials. This review first introduced the general synthesis strategies for manufacturing mesostructured TMP materials, as well as advantages and disadvantages of the respective method; then, we surveyed the ongoing developments of fabrication and application of the TMP materials in three groups on the basis of their components and application fields. Future perspectives on existing problems related to the present synthesis routes and further modifying of the functional groups for the purpose of tailoring special physical-chemical properties to meet wide application requirements were also provided in the last part. PMID:28809304

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miao, Ran; Dutta, Biswanath; Sahoo, Sanjubala

Here, we report a facile synthetic protocol to pre-pare mesoporous FeS 2 without the aid of hard template as an electrocatalyst for the hydrogen evolution reaction (HER). The mesoporous FeS 2 materials with high surface area were successfully prepared by a sol-gel method follow-ing a sulfurization treatment in an H 2S atmosphere. A re-markable HER catalytic performance was achieved with a low overpotential of 96 mV at a current density of 10 mA·cm 2 and a Tafel slope of 78 mV per decade under alka-line conditions (pH 13). These theoretical calculations indicate that the excellent catalytic activity of mesoporous FeSmore » 2 is attributed to the exposed (210) facets. The mesoporous FeS 2 material might be a promising alternative to the Pt-based electrocatalysts for water splitting.« less

Investigating the Effects of Loading Factors on the In Vitro Pharmaceutical Performance of Mesoporous Materials as Drug Carriers for Ibuprofen

PubMed Central

Lai, Junmin; Lin, Wu; Scholes, Peter; Li, Mingzhong

2017-01-01

The aim of the study was to investigate the effects of the loading factors, i.e., the initial drug loading concentration and the ratio of the drug to carriers, on the in vitro pharmaceutical performance of drug-loaded mesoporous systems. Ibuprofen (IBU) was used as a model drug, and two non-ordered mesoporous materials of commercial silica Syloid® 244FP (S244FP) and Neusilin® US2 (NS2) were selected in the study. The IBU-loaded mesoporous samples were prepared by a solvent immersion method with a rotary evaporation drying technique and characterized by polarized light microscopy (PLM), Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC). Dissolution experiments were performed in simulated gastric media at 37 °C under non-sink conditions. The concentration of IBU in solution was determined by HPLC. The study showed that the dissolution rate of IBU can be improved significantly using the mesoporous S224FP carriers due to the conversion of crystalline IBU into the amorphous form. Both of the loading factors affected the IBU dissolution kinetics. Due to the molecular interaction between the IBU and NS2 carriers, the loading factors had little effects on the drug release kinetics with incomplete drug desorption recovery and insignificant dissolution enhancement. Care and extensive evaluation must therefore be taken when mesoporous materials are chosen as carrier delivery systems. PMID:28772509

Carbon spheres-assisted strategy to prepare mesoporous manganese dioxide for supercapacitor applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Siheng; Graduate University of Chinese Academy of Sciences, Beijing 100039; Qi Li, E-mail: qil@ciac.jl.cn

Mesoporous MnO{sub 2} microstructures with large specific surface area have been successfully synthesized by an in-situ redox precipitation method in the presence of colloidal carbon spheres. The samples of them had much higher specific surface area, pore size and pore volume than those obtained via routes without carbon spheres. The morphology, chemical compositions and porous nature of products were fully characterized. Electrochemical measurements showed that these mesoporous MnO{sub 2} could function well when used as positive electrode materials for supercapacitor. Ideal electrochemical capacitive performances and cyclic stability after 2000 galvanostatic charge-discharge cycles could be observed in 1 M neutral Na{submore » 2}SO{sub 4} aqueous electrolyte with a working voltage of 1.7 V. - Graphical Abstract: Mesoporous MnO{sub 2} microstructures with large S{sub BET} were successfully synthesized by in-situ redox precipitation method in the presence of colloidal carbon spheres. Electrochemical measurements showed that these mesoporous MnO{sub 2} could be well used as electrode materials for supercapacitor. Highlights: Black-Right-Pointing-Pointer Mesoporous MnO{sub 2} was prepared by in-situ redox method assisted by carbon spheres. Black-Right-Pointing-Pointer S{sub BET}, pore size and volume were higher than MnO{sub 2} obtained without carbon spheres. Black-Right-Pointing-Pointer They could function well when used as electrode materials for supercapacitor. Black-Right-Pointing-Pointer Ideal capacitive behaviors and long cycling life showed after 2000 charge-discharge.« less

A facile FeBr3 based photoATRP for surface modification of mesoporous silica nanoparticles for controlled delivery cisplatin

NASA Astrophysics Data System (ADS)

Huang, Long; Liu, Meiying; Mao, Liucheng; Huang, Qiang; Huang, Hongye; Zeng, Guangjian; Tian, Jianwen; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

2018-03-01

Mesoporous silica nanoparticles (MSNs) should be one of the most important materials for biomedical application owing to their high specific surface area, regular porous structure, adjustable pore size and chemical inert. However, the biomedical applications of unmodified MSNs are largely impeded for their poor hydrophilicity and lack of functional groups. In this work, a novel photo-initiated atom transfer radical polymerization (ATRP) strategy has been reported for modified mesoporous silica nanoparticles (MSNs) with hydrophilicility copolymers using FeBr3 as the novel photocatalyst and itaconic acid (IA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) as monomers. Because of the hydrophilicity and anticancer agent cis-dichlorodiamineplatinum(II) (CDDP) loading capacity of poly(MPC-co-IA), the controlled drug delivery applications MSNs-NH2-poly(MPC-co-IA) composites toward CDDP were further investigated. A series of characterization results demonstrated that MSNs-NH2-poly(MPC-co-IA) composites can be successfully fabricated through the novel photo-initiated ATRP. MSNs-NH2-poly(MPC-co-IA) composites showed obvious enhancement of water dispersibility, desirable biocompatibility, high drug loading capability, making them great potential for controlled drug delivery of CDDP. Moreover, as compared with the traditional ATRP, that using the transition metal ions and organic ligands as the catalysis systems in elevated temperature, our method provides a more facile, benign and cost-effective route for fabrication of multifunctional MSNs with great potential for biomedical applications. Finally, this FeBr3 based photoATRP strategy should be further extended for the fabrication of many other polymeric composites owing to its good monomer adoptability.

Rare earth (Eu{sup 3+}, Tb{sup 3+}) mesoporous hybrids with calix[4]arene derivative covalently linking MCM-41: Physical characterization and photoluminescence property

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Yajuan; Yan Bing, E-mail: byan@tongji.edu.cn; Wang Li

2011-09-15

MCM-41 mesoporous silica has been functionalized with two kinds of macrocylic calixarene derivatives Calix[4] and Calix[4]Br (Calix[4]=P-tert-butylcalix[4]arene, Calix[4]Br=5.11,17.23-tetra-tert-butyl-25.27-bihydroxy- 26.28-bibromopropoxycalix[4]arene) through condensation approach of tetraethoxysilane (TEOS) in the presence of the cetyltrimethylammonium bromide (CTAB) surfactant as a template. Novel organic-inorganic mesoporous luminescent hybrid containing RE{sup 3+} (Eu{sup 3+}, Tb{sup 3+}) complexes covalently attached to the functionalized ordered mesoporous MCM-41, which are designated as RE-Calix[4]-MCM-41 and RE-Calix[4]Br-MCM-41, respectively, are obtained by sol-gel process. It is found that they all have high surface area, uniform in the mesostructure and good crystallinity. Measurement of the photoluminescence properties show the mesoporous material covalently bonded Tb{supmore » 3+} complexes (Tb-Calix[4]-MCM-41 and Tb-Calix[4]Br-MCM-41) exhibit the stronger characteristic emission of Tb{sup 3+} and longer lifetime than the corresponding Eu-containing materials Eu-Calix[4]-MCM-41 and Eu-Calix[4]Br-MCM-41 due to the triplet state energy of modified organic ligands Calix[4]-Si and Calix[4]Br-Si match with the emissive energy level of Tb{sup 3+} very well. - Graphical abstract: MCM-41 mesoporous silica is functionalized with two kinds of macrocylic calixarene derivatives and luminescent organic-inorganic mesoporous hybrids containing Ln{sup 3+} complexes covalently attached to the functionalized ordered mesoporous MCM-41. Highlights: > Novel linkages of functionalized calixarene derivative. > New rare earth mesoporous hybrids. > Luminescence in visible region.« less

Structural control in the synthesis of inorganic porous materials

NASA Astrophysics Data System (ADS)

Holland, Brian Thomas

Mesoporous (2.0--50.0 nm pore diameter) and macroporous (50.0 nm on up) materials have been the basis of my studies. These materials, for many years, possessed large pore size distributions. Recently, however, it has been possible to synthesize both mesoporous and macroporous materials that possess highly ordered uniform pores throughout the material. Workers at Mobil Corporation in 1992 discovered a hexagonally arrayed mesoporous material, designated MCM-41, which exhibited uniform pores ranging from 2.0--10.0 nm in diameter. In my work MCM-41 was used as a host for the incorporation of meso-tetrakis(5-trimethylammoniumpentyl)porphyrin (TMAP-Cl) and as a model for the synthesis of mesoporous alumino- and galloaluminophosphates which were created using cluster precursors of the type MO4Al 12(OH)24(H2O)12 7+, M = Al or Ga. Macroporous materials with uniform pore sizes have been synthesized by our group with frameworks consisting of a variety of metal oxides, metals, organosilanes, aluminophosphates and bimodal pores. These materials are synthesized from the addition of metal precursors to preordered polystyrene spheres. Removal of the spheres results in the formation of macropores with highly uniform pores extending microns in length. Porous materials with uniform and adjustable pore sizes in the mesoporous and macroporous size regimes offer distinct advantages over non-ordered materials for numerous reasons. First, catalysis reactions that are based on the ability of the porous materials to impose size and shape restrictions on the substrate are of considerable interest in the petroleum and petrochemical industries. As pore diameters increase larger molecules can be incorporated into the pores, i.e., biological molecules, dyes, etc. For the macroporous materials synthesized by our group it has been envisioned that these structures may not only be used for catalysis because of increased efficiencies of flow but for more advanced applications, e.g., photonic crystals, porous electrodes, electrochemical capacitors, etc. One of the more interesting macroporous materials takes advantage of having silicalite as the framework. This bimodal pore material may find use as an acid catalyst as aluminum is doped into the framework.

Writing on the wall with a new synthetic quill

PubMed

MacLachlan; Asefa; Ozin

2000-07-14

A new class of periodic mesoporous organosilicas (PMOs) with organic groups incorporated inside the channel walls of the material is discussed. In particular, the unique properties and chemistry exhibited by periodic mesoporous methylenesilica, an isoelectronic analogue of periodic mesoporous silica, are highlighted. Finally, some of the advances made in our group and others, as well as future directions that we envision in the field are described.

Gravimetric chemical sensors based on silica-based mesoporous organic-inorganic hybrids.

PubMed

Xu, Jiaqiang; Zheng, Qi; Zhu, Yongheng; Lou, Huihui; Xiang, Qun; Cheng, Zhixuan

2014-09-01

Silica-based mesoporous organic-inorganic hybrid material modified quartz crystal microbalance (QCM) sensors have been examined for their ability to achieve highly sensitive and selective detection. Mesoporous silica SBA-15 serves as an inorganic host with large specific surface area, facilitating gas adsorption, and thus leads to highly sensitive response; while the presence of organic functional groups contributes to the greatly improved specific sensing property. In this work, we summarize our efforts in the rational design and synthesis of novel sensing materials for the detection of hazardous substances, including simulant nerve agent, organic vapor, and heavy metal ion, and develop high-performance QCM-based chemical sensors.

Ionic liquid-templated preparation of mesoporous silica embedded with nanocrystalline sulfated zirconia

PubMed Central

2011-01-01

A series of mesoporous silicas impregnated with nanocrystalline sulphated zirconia was prepared by a sol-gel process using an ionic liquid-templated route. The physicochemical properties of the mesoporous sulphated zirconia materials were studied using characterisation techniques such as inductively coupled optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray microanalysis, elemental analysis and X-ray photoelectron spectroscopy. Analysis of the new silicas indicates isomorphous substitution of silicon with zirconium and reveals the presence of extremely small (< 10 nm) polydispersed zirconia nanoparticles in the materials with zirconium loadings from 27.77 to 41.4 wt.%. PMID:21711725

Preparation, characterization and catalytic properties of MCM-48 supported tungstophosphoric acid mesoporous materials for green synthesis of benzoic acid

NASA Astrophysics Data System (ADS)

Wu, Hai-Yan; Zhang, Xiao-Li; Chen, Xi; Chen, Ya; Zheng, Xiu-Cheng

2014-03-01

MCM-48 and tungstophosphoric acid (HPW) were prepared and applied for the synthesis of HPW/MCM-48 mesoporous materials. The characterization results showed that HPW/MCM-48 obtained retained the typical mesopore structure of MCM-48, and the textural parameters decreased with the increase loading of HPW. The catalytic oxidation results of benzyl alcohol and benzaldehyde with 30% H2O2 indicated that HPW/MCM-48 was an efficient catalyst for the green synthesis of benzoic acid. Furthermore, 35 wt% HPW/MCM-48 sample showed the highest activity under the reaction conditions.

Layer-by-Layer Motif Architectures: Programmed Electrochemical Syntheses of Multilayer Mesoporous Metallic Films with Uniformly Sized Pores.

PubMed

Jiang, Bo; Li, Cuiling; Qian, Huayu; Hossain, Md Shahriar A; Malgras, Victor; Yamauchi, Yusuke

2017-06-26

Although multilayer films have been extensively reported, most compositions have been limited to non-catalytically active materials (e.g. polymers, proteins, lipids, or nucleic acids). Herein, we report the preparation of binder-free multilayer metallic mesoporous films with sufficient accessibility for high electrocatalytic activity by using a programmed electrochemical strategy. By precisely tuning the deposition potential and duration, multilayer mesoporous architectures consisting of alternating mesoporous Pd layers and mesoporous PdPt layers with controlled layer thicknesses can be synthesized within a single electrolyte, containing polymeric micelles as soft templates. This novel architecture, combining the advantages of bimetallic alloys, multilayer architectures, and mesoporous structures, exhibits high electrocatalytic activity for both the methanol oxidation reaction (MOR) and the ethanol oxidation reaction (EOR). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enantioselectively controlled release of chiral drug (metoprolol) using chiral mesoporous silica materials

NASA Astrophysics Data System (ADS)

Guo, Zhen; Du, Yu; Liu, Xianbin; Ng, Siu-Choon; Chen, Yuan; Yang, Yanhui

2010-04-01

Chiral porous materials have attracted burgeoning attention on account of their potential applications in many areas, such as enantioseparation, chiral catalysis, chemical sensors and drug delivery. In this report, chiral mesoporous silica (CMS) materials with various pore sizes and structures were prepared using conventional achiral templates (other than chiral surfactant) and a chiral cobalt complex as co-template. The synthesized CMS materials were characterized by x-ray diffraction, nitrogen physisorption, scanning electron microscope and transmission electron microscope. These CMS materials, as carriers, were demonstrated to be able to control the enantioselective release of a representative chiral drug (metoprolol). The release kinetics, as modeled by the power law equation, suggested that the release profiles of metoprolol were remarkably dependent on the pore diameter and pore structure of CMS materials. More importantly, R- and S-enantiomers of metoprolol exhibited different release kinetics on CMS compared to the corresponding achiral mesoporous silica (ACMS), attributable to the existence of local chirality on the pore wall surface of CMS materials. The chirality of CMS materials on a molecular level was further substantiated by vibrational circular dichroism measurements.

Nanostructured mesoporous materials for lithium-ion battery applications

NASA Astrophysics Data System (ADS)

Balaya, P.; Saravanan, K.; Hariharan, S.; Ramar, V.; Lee, H. S.; Kuezma, M.; Devaraj, S.; Nagaraju, D. H.; Ananthanarayanan, K.; Mason, C. W.

2011-06-01

The Energy crisis happens to be one of the greatest challenges we are facing today. In this view, much effort has been made in developing new, cost effective, environmentally friendly energy conversion and storage devices. The performance of such devices is fundamentally related to material properties. Hence, innovative materials engineering is important in solving the energy crisis problem. One such innovation in materials engineering is porous materials for energy storage. Porous electrode materials for lithium-ion batteries (LIBs) offer a high degree of electrolyte-electrode wettability, thus enhancing the electrochemical activity within the material. Among the porous materials, mesoporous materials draw special attention, owing to shorter diffusion lengths for Li+ and electronic movement. Nanostructured mesoporous materials also offer better packing density compared to their nanostructured counterparts such as nanopowders, nanowires, nanotubes etc., thus opening a window for developing electrode materials with high volumetric energy densities. This would directly translate into a scenario of building batteries which are much lighter than today's commercial LIBs. In this article, the authors present a simple, soft template approach for preparing both cathode and anode materials with high packing density for LIBs. The impact of porosity on the electrochemical storage performance is highlighted.

Electrochemical characteristics of discrete, uniform, and monodispersed hollow mesoporous carbon spheres in double-layered supercapacitors.

PubMed

Chen, Xuecheng; Kierzek, Krzysztof; Wenelska, Karolina; Cendrowski, Krzystof; Gong, Jiang; Wen, Xin; Tang, Tao; Chu, Paul K; Mijowska, Ewa

2013-11-01

Core-shell-structured mesoporous silica spheres were prepared by using n-octadecyltrimethoxysilane (C18TMS) as the surfactant. Hollow mesoporous carbon spheres with controllable diameters were fabricated from core-shell-structured mesoporous silica sphere templates by chemical vapor deposition (CVD). By controlling the thickness of the silica shell, hollow carbon spheres (HCSs) with different diameters can be obtained. The use of ethylene as the carbon precursor in the CVD process produces the materials in a single step without the need to remove the surfactant. The mechanism of formation and the role played by the surfactant, C18TMS, are investigated. The materials have large potential in double-layer supercapacitors, and their electrochemical properties were determined. HCSs with thicker mesoporous shells possess a larger surface area, which in turn increases their electrochemical capacitance. The samples prepared at a lower temperature also exhibit increased capacitance as a result of the Brunauer-Emmett-Teller (BET) area and larger pore size. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CuO nanoparticles encapsulated inside Al-MCM-41 mesoporous materials via direct synthetic route

PubMed Central

Huo, Chengli; Ouyang, Jing; Yang, Huaming

2014-01-01

Highly ordered aluminum-containing mesoporous silica (Al-MCM-41) was prepared using attapulgite clay mineral as a Si and Al source. Mesoporous complexes embedded with CuO nanoparticles were subsequently prepared using various copper sources and different copper loadings in a direct synthetic route. The resulting CuO/Al-MCM-41 composite possessed p6mm hexagonally symmetry, well-developed mesoporosity, and relatively high BET surface area. In comparison to pure silica, these mesoporous materials embedded with CuO nanoparticles exhibited smaller pore diameter, thicker pore wall, and enhanced thermal stability. Long-range order in the aforementioned samples was observed for copper weight percentages as high as 30%. Furthermore, a significant blue shift of the absorption edge for the samples was observed when compared with that of bulk CuO. H2-TPR measurements showed that the direct-synthesized CuO/Al-MCM-41 exhibited remarkable redox properties compared to the post-synthesized samples, and most of the CuO nanoparticles were encapsulated within the mesoporous structures. The possible interaction between CuO and Al-MCM-41 was also investigated. PMID:24419589

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moritz, MichaL; Laniecki, Marek, E-mail: laniecki@amu.edu.pl

A series of modified SBA-15 materials were applied in drug delivery systems. The internal surface of siliceous hexagonal structure of SBA-15 was modified with different amount of (3-mercaptopropyl)trimethoxysilane (MPTMS) and oxidized in the presence of hydrogen peroxide. The sulfonated material was loaded with metoprolol tartrate or papaverine hydrochloride. Both drugs indicated strong chemical interaction with modified mesoporous surface. The characteristic of the obtained materials was performed with XRD and DRUV-vis spectrometry, themogravimetry and nitrogen adsorption (BET) measurements. The obtained results show that modification of the mesoporous materials leads towards significant decrease of the drug delivery rate. - Graphical abstract: XRDmore » and DSC of the -SO{sub 3}H modified SBA-15 loaded with metoprolol. Highlights: > Modification of SBA-15 internal channels with SO{sub 3}H groups. > Adsorption of metoprolol and papaverine on modified SBA-15. > Uniform and homogeneous distribution of the drugs inside the mesoporous structure of SBA-15. > Release of the supported drugs.« less

Incorporating Rich Mesoporosity into a Ceria-Based Catalyst via Mechanochemistry

DOE PAGES

Zhan, Wangcheng; Yang, Shize; Zhang, Pengfei; ...

2017-08-15

Ceria-based materials possessing mesoporous structures afford higher activity than the corresponding bulk materials in CO oxidation and other catalytic applications, because of the wide pore channel and high surface area. The development of a direct, template-free, and scalable technology for directing porosity inside ceriabased materials is highly welcome. Here in this paper, a family of mesoporous transition-metaldoped ceria catalysts with specific surface areas up to 122 m 2 g -1 is constructed by mechanochemical grinding. No templates, additives, or solvents are needed in this process, while the mechanochemistry-mediated restructuring and the decomposing of the organic group led to plentiful mesopores.more » Interestingly, the copper species are evenly dispersed in the ceria matrix at the atomic scale, as observed in high resolution scanning transmission electron microscopy in high angle annular dark field. The copper-doped ceria materials show good activity in the CO oxidation.« less

Synthesis of nitrogen- and sulfur-codoped 3D cubic-ordered mesoporous carbon with superior performance in supercapacitors.

PubMed

Zhang, Deyi; Zheng, Liweng; Ma, Ying; Lei, Longyan; Li, Qinglin; Li, Yan; Luo, Heming; Feng, Huixia; Hao, Yuan

2014-02-26

In this contribution, nitrogen- and sulfur-codoped 3D cubic-ordered mesoporous carbon (KNOMC) materials with controlled dopant content (10.0-4.6 atom % for nitrogen and 0.94-0.75 atom % for sulfur) are presented, using KIT-6 as the template and pyrrole as the precursor, and its supercapacitive behavior is also investigated. The presented materials exhibit excellent supercapacitive performance by combining electrical double-layer capacitance and pseudocapacitance as well as the enhanced wettability and improved conductivity generated from the incorporation of nitrogen and sulfur into the framework of carbon materials. The specific capacitance of the presented materials reaches 320 F g(-1) at a current density of 1 A g(-1), which is significantly larger than that of the pristine-ordered mesoporous carbon reported in the literature and can even compete with some metal oxides and conducting polymers.

Two New Fluorogenic Aptasensors Based on Capped Mesoporous Silica Nanoparticles to Detect Ochratoxin A

PubMed Central

Ribes, Àngela; Santiago‐Felipe, Sara; Bernardos, Andrea; Marcos, M. Dolores; Pardo, Teresa; Sancenón, Félix; Aznar, Elena

2017-01-01

Abstract Aptamers have been used as recognition elements for several molecules due to their great affinity and selectivity. Additionally, mesoporous nanomaterials have demonstrated great potential in sensing applications. Based on these concepts, we report herein the use of two aptamer‐capped mesoporous silica materials for the selective detection of ochratoxin A (OTA). A specific aptamer for OTA was used to block the pores of rhodamine B‐loaded mesoporous silica nanoparticles. Two solids were prepared in which the aptamer capped the porous scaffolds by using a covalent or electrostatic approach. Whereas the prepared materials remained capped in water, dye delivery was selectively observed in the presence of OTA. The protocol showed excellent analytical performance in terms of sensitivity (limit of detection: 0.5–0.05 nm), reproducibility, and selectivity. Moreover, the aptasensors were tested for OTA detection in commercial foodstuff matrices, which demonstrated their potential applicability in real samples. PMID:29046860

Monodisperse Fe3O4 and γ-Fe2O3 magnetic mesoporous microspheres as anode materials for lithium-ion batteries.

PubMed

Xu, Jing-San; Zhu, Ying-Jie

2012-09-26

Monodisperse Fe(3)O(4) and γ-Fe(2)O(3) magnetic mesoporous microspheres are prepared via a surfactant-free solvothermal combined with precursor thermal transformation method. The as-prepared Fe(3)O(4) and γ-Fe(2)O(3) magnetic mesoporous microspheres have a relatively high specific surface area of 122.3 and 138.6 m(2)/g, respectively. The Fe(3)O(4) and γ-Fe(2)O(3) magnetic mesoporous microspheres are explored as the anode materials for lithium-ion batteries, and they have a high initial discharge capacity of 1307 and 1453 mA h/g, respectively, and a good reversible performance (450 mA h/g for Fe(3)O(4) and 697 mA h/g for γ-Fe(2)O(3) after 110 cycles) at the current density of 0.2C.

Mesoporous titanium phosphate molecular sieves with ion-exchange capacity.

PubMed

Bhaumik, A; Inagaki, S

2001-01-31

Novel open framework molecular sieves, titanium(IV) phosphates named, i.e., TCM-7 and -8 (Toyota Composite Materials, numbers 7 and 8), with new mesoporous cationic framework topologies obtained by using both cationic and anionic surfactants are reported. The (31)P MAS NMR, UV-visible absorption, and XANES data suggest the tetrahedral state of P and Ti, and stabilization of the tetrahedral state of Ti in TCM-7/8 is due to the incorporation of phosphorus (at Ti/P = 1:1) vis-à-vis the most stable octahedral state of Ti in the pure mesoporous TiO(2). Mesoporous TCM-7 and -8 show anion exchange capacity due to the framework phosphonium cation and cation exchange capacity due to defective P-OH groups. The high catalytic activity in the liquid-phase partial oxidation of cyclohexene with a dilute H(2)O(2) oxidant supports the tetrahedral coordination of Ti in these materials.

Block copolymer self-assembly–directed synthesis of mesoporous gyroidal superconductors

PubMed Central

Robbins, Spencer W.; Beaucage, Peter A.; Sai, Hiroaki; Tan, Kwan Wee; Werner, Jörg G.; Sethna, James P.; DiSalvo, Francis J.; Gruner, Sol M.; Van Dover, Robert B.; Wiesner, Ulrich

2016-01-01

Superconductors with periodically ordered mesoporous structures are expected to have properties very different from those of their bulk counterparts. Systematic studies of such phenomena to date are sparse, however, because of a lack of versatile synthetic approaches to such materials. We demonstrate the formation of three-dimensionally continuous gyroidal mesoporous niobium nitride (NbN) superconductors from chiral ABC triblock terpolymer self-assembly–directed sol-gel–derived niobium oxide with subsequent thermal processing in air and ammonia gas. Superconducting materials exhibit a critical temperature (Tc) of about 7 to 8 K, a flux exclusion of about 5% compared to a dense NbN solid, and an estimated critical current density (Jc) of 440 A cm−2 at 100 Oe and 2.5 K. We expect block copolymer self-assembly–directed mesoporous superconductors to provide interesting subjects for mesostructure-superconductivity correlation studies. PMID:27152327

Block copolymer self-assembly-directed synthesis of mesoporous gyroidal superconductors.

PubMed

Robbins, Spencer W; Beaucage, Peter A; Sai, Hiroaki; Tan, Kwan Wee; Werner, Jörg G; Sethna, James P; DiSalvo, Francis J; Gruner, Sol M; Van Dover, Robert B; Wiesner, Ulrich

2016-01-01

Superconductors with periodically ordered mesoporous structures are expected to have properties very different from those of their bulk counterparts. Systematic studies of such phenomena to date are sparse, however, because of a lack of versatile synthetic approaches to such materials. We demonstrate the formation of three-dimensionally continuous gyroidal mesoporous niobium nitride (NbN) superconductors from chiral ABC triblock terpolymer self-assembly-directed sol-gel-derived niobium oxide with subsequent thermal processing in air and ammonia gas. Superconducting materials exhibit a critical temperature (T c) of about 7 to 8 K, a flux exclusion of about 5% compared to a dense NbN solid, and an estimated critical current density (J c) of 440 A cm(-2) at 100 Oe and 2.5 K. We expect block copolymer self-assembly-directed mesoporous superconductors to provide interesting subjects for mesostructure-superconductivity correlation studies.

Ceramic porous material and method of making same

DOEpatents

Liu, Jun; Kim, Anthony Y.; Virden, Jud W.

1997-01-01

The invention is a mesoporous ceramic membrane having substantially uniform pore size. Additionally, the invention includes aqueous and non-aqueous processing routes to making the mesoporous ceramic membranes. According to one aspect of the present invention, inserting a substrate into a reaction chamber at pressure results in reaction products collecting on the substrate and forming a membrane thereon. According to another aspect of the present invention, a second aqueous solution that is sufficiently immiscible in the aqueous solution provides an interface between the two solutions whereon the mesoporous membrane is formed. According to a further aspect of the present invention, a porous substrate is placed at the interface between the two solutions permitting formation of a membrane on the surface or within the pores of the porous substrate. According to yet another aspect of the present invention, mesoporous ceramic materials are formed using a non-aqueous solvent and water-sensitive precursors.

Ceramic porous material and method of making same

DOEpatents

Liu, J.; Kim, A.Y.; Virden, J.W.

1997-07-08

The invention is a mesoporous ceramic membrane having substantially uniform pore size. Additionally, the invention includes aqueous and non-aqueous processing routes to making the mesoporous ceramic membranes. According to one aspect of the present invention, inserting a substrate into a reaction chamber at pressure results in reaction products collecting on the substrate and forming a membrane thereon. According to another aspect of the present invention, a second aqueous solution that is sufficiently immiscible in the aqueous solution provides an interface between the two solutions whereon the mesoporous membrane is formed. According to a further aspect of the present invention, a porous substrate is placed at the interface between the two solutions permitting formation of a membrane on the surface or within the pores of the porous substrate. According to yet another aspect of the present invention, mesoporous ceramic materials are formed using a non-aqueous solvent and water-sensitive precursors. 21 figs.

Highly mesoporous single-crystalline zeolite beta synthesized using a nonsurfactant cationic polymer as a dual-function template.

PubMed

Zhu, Jie; Zhu, Yihan; Zhu, Liangkui; Rigutto, Marcello; van der Made, Alexander; Yang, Chengguang; Pan, Shuxiang; Wang, Liang; Zhu, Longfeng; Jin, Yinying; Sun, Qi; Wu, Qinming; Meng, Xiangju; Zhang, Daliang; Han, Yu; Li, Jixue; Chu, Yueying; Zheng, Anmin; Qiu, Shilun; Zheng, Xiaoming; Xiao, Feng-Shou

2014-02-12

Mesoporous zeolites are useful solid catalysts for conversion of bulky molecules because they offer fast mass transfer along with size and shape selectivity. We report here the successful synthesis of mesoporous aluminosilicate zeolite Beta from a commercial cationic polymer that acts as a dual-function template to generate zeolitic micropores and mesopores simultaneously. This is the first demonstration of a single nonsurfactant polymer acting as such a template. Using high-resolution electron microscopy and tomography, we discovered that the resulting material (Beta-MS) has abundant and highly interconnected mesopores. More importantly, we demonstrated using a three-dimensional electron diffraction technique that each Beta-MS particle is a single crystal, whereas most previously reported mesoporous zeolites are comprised of nanosized zeolitic grains with random orientations. The use of nonsurfactant templates is essential to gaining single-crystalline mesoporous zeolites. The single-crystalline nature endows Beta-MS with better hydrothermal stability compared with surfactant-derived mesoporous zeolite Beta. Beta-MS also exhibited remarkably higher catalytic activity than did conventional zeolite Beta in acid-catalyzed reactions involving large molecules.

Fast and efficient mesoporous adsorbents for the separation of toxic compounds from aqueous media.

PubMed

Anbia, Mansoor; Mohammadi, Nourali; Mohammadi, Kaveh

2010-04-15

The effect of cationic template on the adsorption of chromium (VI), furfural and copperphthalocyanine-3,4',4'',4'''-tetrasulfonic acid tetrasodium salt (CuPc) in MCM-41 and MCM-48 mesoporous materials was investigated in this work. We used cetyltrimethylammonium bromide (CTAB) as the cationic template and sodiummetasilicate (for MCM-41) and tetraethyl-orthosilicon (for MCM-48) as the silica source for the synthesis of mesoporous materials. The properties of synthesized samples were characterized with XRD-low angle, SEM, N(2) adsorption-desorption and TG-DT analysis. The extent of adsorption was investigated as a function of solution pH, shaking speed, contact time, analyte concentration, reaction temperature and supporting electrolyte (sodium chloride) concentration. Langmuir and Freundlich isotherms were used to model the adsorption equilibrium data. The as-synthesized mesoporous samples showed very high adsorption capacity for the analytes and adsorption uptakes were rapid on the adsorbents reaching equilibrium in less than 2 h. The materials without surfactant did not show significant affinity for the analytes. 2009 Elsevier B.V. All rights reserved.

Tri-metallic PtPdAu mesoporous nanoelectrocatalysts.

PubMed

Li, Chunjie; Wang, Hongjing; Li, Yinghao; Yu, Hongjie; Yin, Shuli; Xue, Hairong; Li, Xiaonian; Xu, You; Wang, Liang

2018-06-22

The design of mesoporous materials with multi-metallic compositions is highly important for various electrocatalytic applications. In this paper, we demonstrate an efficient method to directly fabricate tri-metallic PtPdAu mesoporous nanoparticles (PtPdAu MNs) in a high yield, which is simply performed by heating treatment of the reaction mixture aqueous solution at 40 °C for 4 h. Profiting from its mesoporous structure and multi-metallic components, the as-prepared PtPdAu MNs exhibit enhanced electrocatalytic activities toward both methanol oxidation reaction and oxygen reduction reaction in comparison with bi-metallic PtPd MNs and commercial Pt/C catalyst.

Tri-metallic PtPdAu mesoporous nanoelectrocatalysts

NASA Astrophysics Data System (ADS)

Li, Chunjie; Wang, Hongjing; Li, Yinghao; Yu, Hongjie; Yin, Shuli; Xue, Hairong; Li, Xiaonian; Xu, You; Wang, Liang

2018-06-01

The design of mesoporous materials with multi-metallic compositions is highly important for various electrocatalytic applications. In this paper, we demonstrate an efficient method to directly fabricate tri-metallic PtPdAu mesoporous nanoparticles (PtPdAu MNs) in a high yield, which is simply performed by heating treatment of the reaction mixture aqueous solution at 40 °C for 4 h. Profiting from its mesoporous structure and multi-metallic components, the as-prepared PtPdAu MNs exhibit enhanced electrocatalytic activities toward both methanol oxidation reaction and oxygen reduction reaction in comparison with bi-metallic PtPd MNs and commercial Pt/C catalyst.

Synthesis of wrinkled mesoporous silica and its reinforcing effect for dental resin composites.

PubMed

Wang, Ruili; Habib, Eric; Zhu, X X

2017-10-01

The aim of this work is to explore the reinforcing effect of wrinkled mesoporous silica (WMS), which should allow micromechanical resin matrix/filler interlocking in dental resin composites, and to investigate the effect of silica morphology, loading, and compositions on their mechanical properties. WMS (average diameter of 496nm) was prepared through the self-assembly method and characterized by the use of the electron microscopy, dynamic light scattering, and the N 2 adsorption-desorption measurements. The mechanical properties of resin composites containing silanized WMS and nonporous smaller silica were evaluated with a universal mechanical testing machine. Field-emission scanning electron microscopy was used to study the fracture morphology of dental composites. Resin composites including silanized silica particles (average diameter of 507nm) served as the control group. Higher filler loading of silanized WMS substantially improved the mechanical properties of the neat resin matrix, over the composites loaded with regular silanized silica particles similar in size. The impregnation of smaller secondary silica particles with diameters of 90 and 190nm, denoted respectively as Si90 and Si190, increased the filler loading of the bimodal WMS filler (WMS-Si90 or WMS-Si190) to 60wt%, and the corresponding composites exhibited better mechanical properties than the control fillers made with regular silica particles. Among all composites, the optimal WMS-Si190- filled composite (mass ratio WMS:Si190=10:90, total filler loading 60wt%) exhibited the best mechanical performance including flexural strength, flexural modulus, compressive strength and Vickers microhardness. The incorporation of WMS and its mixed bimodal fillers with smaller silica particles led to the design and formulation of dental resin composites with superior mechanical properties. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Liquid Photonic Crystals for Mesopore Detection.

PubMed

Zhu, Biting; Fu, Qianqian; Chen, Ke; Ge, Jianping

2018-01-02

Nitrogen adsorption-desorption for mesopore characterization requires the using of expensive instrumentation, time-consuming processes, and the consumption of liquid nitrogen. Herein, a new method is developed to measure the pore parameters through mixing a mesoporous substance with a supersaturated SiO 2 colloidal solution at different temperatures, and subsequent rapid measurement of reflection changes of the precipitated liquid photonic crystals. The pore volumes and diameters of mesoporous silica were measured according to the positive correlation between unit mass reflection change (Δλ/m) and pore volume (V), and the negative correlation between average absorption temperature (T) and pore diameter (D). This new approach may provide an alternative method for fast, convenient and economical characterization of mesoporous materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catalytic performance of strong acid catalyst: Methyl modified SBA-15 loaded perfluorinated sulfonic acid obtained by the waste perfluorinated sulfonic acid ion exchange membrane

NASA Astrophysics Data System (ADS)

Jiang, Tingshun; Huang, Qiuyan; Li, Yingying; Fang, Minglan; Zhao, Qian

2018-02-01

Mesoporous molecular sieve (SBA-15) was modified using the trimethylchlorosilane as functional agent and the silylation SBA-15 mesoporous material was prepared in this work. The alcohol solution of perfluorinated sulfonic acid dissolved from the waste perfluorinated sulfonic acid ion exchange membrane (PFSIEM) was loaded onto the resulting mesoporous material by the impregnation method and their physicochemical properties were characterized by FT-IR, N2-physisorption, XRD, TG-DSC and TEM. The catalytic activities of these synthesized solid acid catalysts were evaluated by alkylation of phenol with tert-butyl alcohol. The influence of reaction temperature, weight hour space velocity (WHSV) and reaction time on the phenol conversion and product selectivity were assessed by means of a series of experiments. The results showed that with the increase of the active component of the catalyst, these catalysts still remained good mesoporous structure, but the mesoporous ordering decreased to some extent. These catalysts exhibited good catalytic performance for the alkylation of phenol with tert-butanol. The maximum phenol conversion of 89.3% with 70.9% selectivity to 4-t-butyl phenol (4-TBP) was achieved at 120 °C and the WHSV is 4 h-1. The methyl group was loaded on the surface of the catalyst by trimethylchlorosilane. This is beneficial to retard the deactivation of the catalyst. In this work, the alkylation of phenol with tert-butyl alcohol were carried out using the methyl modified SBA-15 mesoporous materials loaded perfluorinated sulfonic acid as catalysts. The results show that the resulting catalyst exhibited high catalytic activity.

Synthesis of Ordered Mesoporous CuO/CeO2 Composite Frameworks as Anode Catalysts for Water Oxidation

PubMed Central

Markoulaki, Vassiliki Ι.; Papadas, Ioannis T.; Kornarakis, Ioannis; Armatas, Gerasimos S.

2015-01-01

Cerium-rich metal oxide materials have recently emerged as promising candidates for the photocatalytic oxygen evolution reaction (OER). In this article, we report the synthesis of ordered mesoporous CuO/CeO2 composite frameworks with different contents of copper(II) oxide and demonstrate their activity for photocatalytic O2 production via UV-Vis light-driven oxidation of water. Mesoporous CuO/CeO2 materials have been successfully prepared by a nanocasting route, using mesoporous silica as a rigid template. X-ray diffraction, electron transmission microscopy and N2 porosimetry characterization of the as-prepared products reveal a mesoporous structure composed of parallel arranged nanorods, with a large surface area and a narrow pore size distribution. The molecular structure and optical properties of the composite materials were investigated with Raman and UV-Vis/NIR diffuse reflectance spectroscopy. Catalytic results indicated that incorporation of CuO clusters in the CeO2 lattice improved the photochemical properties. As a result, the CuO/CeO2 composite catalyst containing ~38 wt % CuO reaches a high O2 evolution rate of ~19.6 µmol·h−1 (or 392 µmol·h−1·g−1) with an apparent quantum efficiency of 17.6% at λ = 365 ± 10 nm. This OER activity compares favorably with that obtained from the non-porous CuO/CeO2 counterpart (~1.3 µmol·h−1) and pure mesoporous CeO2 (~1 µmol·h−1). PMID:28347106

Packaging biological cargoes in mesoporous materials: opportunities for drug delivery.

PubMed

Siefker, Justin; Karande, Pankaj; Coppens, Marc-Olivier

2014-11-01

Confinement of biomolecules in structured nanoporous materials offers several desirable features ranging from chemical and thermal stability, to resistance to degradation from the external environment. A new generation of mesoporous materials presents exciting new possibilities for the formulation and controlled release of biological agents. Such materials address niche applications in enteral and parenteral delivery of biologics, such as peptides, polypeptides, enzymes and proteins for use as therapeutics, imaging agents, biosensors, and adjuvants. Mesoporous silica Santa Barbara Amorphous-15 (SBA-15), with its unique, tunable pore diameter, and easily functionalized surface, provides a representative example of this new generation of materials. Here, we review recent advances in the design and synthesis of nanostructured mesoporous materials, focusing on SBA-15, and highlight opportunities for the delivery of biological agents to various organ and tissue compartments. The SBA-15 platform provides a delivery carrier that is inherently separated from the active biologic due to distinct intra and extra-particle environments. This permits the SBA-15 platform to not require direct modification of the active biological therapeutic. Additionally, this makes the platform universal and allows for its application independent of the desired methods of discovery and development. The SBA-15 platform also directly addresses issues of targeted delivery and controlled release, although future challenges in the implementation of this platform reside in particle design, biocompatibility, and the tunability of the internal and external material properties. Examples illustrating the flexibility in the application of the SBA-15 platform are also discussed.

Structural and diffusion characterizations of steam-stable mesostructured zeolitic UL-ZSM-5 materials.

PubMed

Vinh-Thang, Hoang; Huang, Qinglin; Ungureanu, Adrian; Eić, Mladen; Trong-On, Do; Kaliaguine, Serge

2006-05-09

A series of mesoporous UL-ZSM-5 materials (Si/Al = 50) with different micro- and mesoporosity as well as crystallinity was prepared following the procedure proposed in one of our recent studies (Trong-On, D.; Kaliaguine, S. Angew. Chem. Int. Ed. 2001, 40, 3248-3251. Trong-On, D.; Kaliaguine, S. U.S. Patent 6,669,924, B1, 2003). These materials have zeolitic structure in the form of nanoparticles intergrown in the walls of the amorphous wormhole-like aluminosilicate mesopores of Al-Meso-50, which was used as a precursor in the synthesis. The structure, crystallinity, and textural properties of the synthesized materials, as well as a reference ZSM-5 zeolite sample, were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM)/scanning electron microscoy (SEM) analyses, Fourier transform infrared spectroscopy (FTIR), 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR), and nitrogen adsorption/desorption techniques. The acid properties were examined by FTIR of adsorbed pyridine. UL-ZSM-5 materials were shown to be highly hydrothermally stable. The diffusion of two C7 hydrocarbons, i.e., n-heptane and toluene, in four UL-ZSM-5 materials with different microporosities, related acidities, and crystallinities were investigated using the zero-length column (ZLC) method. Furthermore, the wormhole-like mesostructured aluminosilicate precursor (Al-Meso-50) and a reference MFI zeolite sample were also investigated using the same technique. A theoretical model considering a combination of mesopore diffusion (with surface slip in the main channels) with an activated, mainly surface diffusion mechanism in the intrawall biporous structure, was proposed and employed to interpret the experimental ZLC results. A classical Knudsen type of diffusion was replaced by an activated surface slip type of diffusion mechanism in the mesopores. The transport of n-heptane in UL-ZSM-5 materials was found to be mainly controlled by mesopore diffusion in the main-channel structure, while that of toluene was dominated by the intrawall diffusion process. Diffusion activation energies of n-heptane are about 2 times higher in comparison to toluene, which has a larger kinetic diameter. The main mesopore channel structure seems to appreciably contribute to the overall mass transport. Furthermore, the effect of hydrothermal treatment (20% steam at 800 degrees C for 24 h) on the diffusion of these two sorbates on UL-ZSM-5 materials was also evaluated.

Mesoporous titanosilicates with high loading of titanium synthesized in mild acidic buffer solution.

PubMed

Tang, Jianting; Liu, Jian; Yang, Jie; Feng, Zhaochi; Fan, Fengtao; Yang, Qihua

2009-07-15

Mesoporous titanosilicates with high titanium content were synthesized under mild acidic conditions (pH=4.4, HAc-NaAc buffer solution) by co-condensation of acetylacetone-modified titanium isopropoxide (Ti(OBu(n))(3) (acac)) and mixture of sodium silicate with tetramethoxysilane (TMOS) or tetraethoxysilane (TEOS) or tetrakis(2-hydroxyethyl)orthosilicate (EGMS), using block copolymer Pluronic P123 as template. The combined results of XRD, N(2) sorption and TEM show that the highly regular structure of the mesoporous titanosilicates can still be obtained when Ti/Si molar ratio in the final product is as high as 0.059. The results of UV-vis diffuse reflectance spectra and UV resonance Raman spectra show that the framework titanium species are predominant in the mesoporous titanosilicates when Ti/Si molar ratio in the final product is less than 0.042. The mixture of sodium silicate and EGMS was proved to be the best silicon source for the synthesis of titanosilicates with ordered mesostructure and high titanium content. The efficiency of this synthetic method may be attributed to the mild acidic medium as well as the modified hydrolysis-condensation rate and hydrophility of the precursors.

SiC-dopped MCM-41 materials with enhanced thermal and hydrothermal stabilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yingyong; Jin, Guoqiang; Tong, Xili

2011-11-15

Graphical abstract: Novel SiC-dopped MCM-41 materials were synthesized by adding silicon carbide suspension in the molecular sieve precursor solvent followed by in situ hydrothermal synthesis. The dopped materials have a wormhole-like mesoporous structure and exhibit enhanced thermal and hydrothermal stabilities. Highlights: {yields} SiC-dopped MCM-41 was synthesized by in situ hydrothermal synthesis of molecular sieve precursor combined with SiC. {yields} The dopped MCM-41 materials show a wormhole-like mesoporous structure. {yields} The thermal stability of the dopped materials have an increment of almost 100 {sup o}C compared with the pure MCM-41. {yields} The hydrothermal stability of the dopped materials is also bettermore » than that of the pure MCM-41. -- Abstract: SiC-dopped MCM-41 mesoporous materials were synthesized by the in situ hydrothermal synthesis, in which a small amount of SiC was added in the precursor solvent of molecular sieve before the hydrothermal treatment. The materials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N{sub 2} physical adsorption and thermogravimetric analysis, respectively. The results show that the thermal and hydrothermal stabilities of MCM-41 materials can be improved obviously by incorporating a small amount of SiC. The structure collapse temperature of SiC-dopped MCM-41 materials is 100 {sup o}C higher than that of pure MCM-41 according to the differential scanning calorimetry analysis. Hydrothermal treatment experiments also show that the pure MCM-41 will losses it's ordered mesoporous structure in boiling water for 24 h while the SiC-dopped MCM-41 materials still keep partial porous structure.« less

Design, fabrication, and testing of nanostructured carbons and composites

NASA Astrophysics Data System (ADS)

Wang, Zhiyong

Many applications, such as catalysis, sensing, separation and energy storage and conversion, will benefit from the miniaturization of materials to nanometer length scales. This dissertation details my study of nanocomposites based on three-dimensionally ordered macroporous (3DOM) carbons and zirconia, and three-dimensionally ordered macroporous/mesoporous (3DOM/m) carbons. The macropores of these materials were produced using colloidal crystal templates while the mesopores were generated using surfactant templates. These solids are composed of close-packed and three-dimensionally interconnected spherical macropores surrounded by nanoscale solid or mesoporous wall skeletons. This unique architecture offers large surface areas, pore volumes, and good access into the bulk via a macroporous network. 3DOM carbons have been demonstrated as promising electrode materials for lithium ion batteries and sensors, but their electrochemical performance still needs to be improved. As a model system for the modification of the electrode, 3DOM C/TiO2 was synthesized by fabricating a conformal coating of TiO2 nanoparticles on the macropore walls of 3DOM C. My research further extended the micro-structural design of monolithic carbon from 3DOM to 3DOM/m. 3DOM/m C monoliths with high surface areas, controllable mesopore sizes, and mesopore ordering, were synthesized by three methods. One of the methods is simpler and more environment benign than previously reported methods. The mesopores in 3DOM/m C-based electrode provide room to accommodate secondary phases, such as graphitic carbon, SnO2 and Si which can improve the conductivity or lithium capacity of the electrode. Owing to this advantage, 3DOM/m C/C and 3DOM/m C/SnO2 exhibited significantly improved rate performance, lithium capacity and cycleability, compared with 3DOM C. To meet the demands of nano-sized functional materials in applications such as nano-device fabrication and drug delivery, mesoporous carbon nanoparticles with cubic, spherical and tetrapod shapes were also synthesized. In addition, new methods were developed to assemble nanocomposites of bifunctional catalyst components. These materials were designed for the potential direct conversion of synthesis gas to clean liquid fuels. Coatings of zeolite and cobalt nanoparticles were fabricated on 3DOM promoted zirconia. The 3DOM zirconia-based nanocomposites were characterized by a wide variety of techniques to illustrate their morphologies, internal structures, chemical compositions, porosity, and crystallographic phases.

Structural and magnetic properties of the nanocomposite materials based on a mesoporous silicon dioxide matrix

NASA Astrophysics Data System (ADS)

Grigor'eva, N. A.; Eckerlebe, H.; Eliseev, A. A.; Lukashin, A. V.; Napol'skii, K. S.; Kraje, M.; Grigor'ev, S. V.

2017-03-01

The structural and magnetic properties of the mesoporous systems based on silicon dioxide with a regular hexagonal arrangement of pores several microns in length and several nanometers in diameter, which are filled with iron compound nanofilaments in various chemical states, are studied in detail. The studies are performed using the following mutually complementary methods: transmission electron microscopy, SQUID magnetometry, electron spin resonance, Mössbauer spectroscopy, polarized neutron small-angle diffraction, and synchrotron radiation diffraction. It is shown that the iron nanoparticles in pores are mainly in the γ phase of Fe2O3 with a small addition of the α phase and atomic iron clusters. The effective magnetic field acting on a nanofilament from other nanofilaments is 11 mT and has a dipole nature, the ferromagnetic-paramagnetic transition temperature is in the range 76-94 K depending on the annealing temperature of the samples, and the temperature that corresponds to the change in the magnetic state of the iron oxide nanofilaments is T ≈ 50-60 K at H = 0 and T ≈ 80 K at H = 300 mT. It is also shown that the magnetization reversal of an array of nanofilaments is caused by the magnetostatic interaction between nanofilaments at the fields that are lower than the saturation field.

The development of chiral nematic mesoporous materials.

PubMed

Kelly, Joel A; Giese, Michael; Shopsowitz, Kevin E; Hamad, Wadood Y; MacLachlan, Mark J

2014-04-15

Cellulose nanocrystals (CNCs) are obtained from the sulfuric acid-catalyzed hydrolysis of bulk cellulose. The nanocrystals have diameters of ~5-15 nm and lengths of ~100-300 nm (depending on the cellulose source and hydrolysis conditions). This lightweight material has mostly been investigated to reinforce composites and polymers because it has remarkable strength that rivals carbon nanotubes. But CNCs have an additional, less explored property: they organize into a chiral nematic (historically referred to as cholesteric) liquid crystal in water. When dried into a thin solid film, the CNCs retain the helicoidal chiral nematic order and assemble into a layered structure where the CNCs have aligned orientation within each layer, and their orientation rotates through the stack with a characteristic pitch (repeating distance). The cholesteric ordering can act as a 1-D photonic structure, selectively reflecting circularly polarized light that has a wavelength nearly matching the pitch. During CNC self-assembly, it is possible to add sol-gel precursors, such as Si(OMe)4, that undergo hydrolysis and condensation as the solvent evaporates, leading to a chiral nematic silica/CNC composite material. Calcination of the material in air destroys the cellulose template, leaving a high surface area mesoporous silica film that has pore diameters of ~3-10 nm. Importantly, the silica is brilliantly iridescent because the pores in its interior replicate the chiral nematic structure. These films may be useful as optical filters, reflectors, and membranes. In this Account, we describe our recent research into mesoporous films with chiral nematic order. Taking advantage of the chiral nematic order and nanoscale of the CNC templates, new functional materials can be prepared. For example, heating the silica/CNC composites under an inert atmosphere followed by removal of the silica leaves highly ordered, mesoporous carbon films that can be used as supercapacitor electrodes. The composition of the mesoporous films can be varied by using assorted organosilica precursors. After removal of the cellulose by acid-catalyzed hydrolysis, highly porous, iridescent organosilica films are obtained. These materials are flexible and offer the ability to tune the chemical and mechanical properties through variation of the organic spacer. Chiral nematic mesoporous silica and organosilica materials, obtainable as centimeter-scale freestanding films, are interesting hosts for nanomaterials. When noble metal nanoparticles are incorporated into the pores, they show strong circular dichroism signals associated with their surface plasmon resonances that arise from dipolar coupling of the particles within the chiral nematic host. Fluorescent conjugated polymers show induced circular dichroism spectra when encapsulated in the chiral nematic host. The porosity, film structure, and optical properties of these materials could enable their use in sensors. We describe the development of chiral nematic mesoporous silica and organosilica, demonstrate different avenues of host-guest chemistry, and identify future directions that exploit the unique combination of properties present in these materials. The examples covered in this Account demonstrate that there is a rich diversity of composite materials accessible using CNC templating.

Synthesis of an Ionic Liquid and Its Application as Template for the Preparation of Mesoporous Material MCM-41: A Comprehensive Experiment for Undergraduate Students

ERIC Educational Resources Information Center

Hu, Jun; Yin, Jinxiang; Lin, Tianshu; Li, Guangtao

2012-01-01

A new solvent-free microwave experiment to synthesize the ionic liquid 1-hexadecyl-3-methylimidazolium bromide (HDMIm-Br) in high yield is presented. The structure is confirmed by IR and [superscript 1]H NMR spectra. HDMIm-Br is then used to prepare an organic-inorganic mesoporous material MCM-41. The microscopic arrangements of mesoporous…

Ordered mesoporous ferrosilicate materials with highly dispersed iron oxide nanoparticles and investigation of their unique magnetic properties.

PubMed

Srinivasu, Pavuluri; Suresh, Koppoju; Datt, Gopal; Abhayankar, Ashutosh C; Rao, Pothuraju Nageswara; Lakshmi Kantam, Mannepalli; Bhargava, Suresh K; Tang, Jing; Yamauchi, Yusuke

2014-11-07

Ordered mesoporous ferrosilicate materials with highly dispersed iron oxide nanoparticles are directly synthesized through a hydrothermal approach under acidic conditions. The obtained samples possess a high surface area (up to 1236 m(2) g(-1)) and a large pore volume (up to 1.1 cm(3) g(-1)). By changing the amount of iron content, the magnetic properties can be tuned.

Synthesis and characterization of alkyl-imidazolium-based periodic mesoporous organosilicas: a versatile host for the immobilization of perruthenate (RuO4-) in the aerobic oxidation of alcohols.

PubMed

Karimi, Babak; Elhamifar, Dawood; Yari, Omolbanin; Khorasani, Mojtaba; Vali, Hojatollah; Clark, James H; Hunt, Andrew J

2012-10-15

The preparation and characterization of a set of periodic mesoporous organosilicas (PMOs) that contain different fractions of 1,3-bis(3-trimethoxysilylpropyl)imidazolium chloride (BTMSPI) groups uniformly distributed in the silica mesoporous framework is described. The mesoporous structure of the materials was characterized by powder X-ray diffraction, transmission electron microscopy, and N(2) adsorption-desorption analysis. The presence of propyl imidazolium groups in the silica framework of the materials was also characterized by solid-state NMR spectroscopy and diffuse-reflectance Fourier-transform infrared spectroscopy. The effect of the BTMSPI concentration in the initial solutions on the structural properties (including morphology) of the final materials was also examined. The total organic content of the PMOs was measured by elemental analysis, whereas their thermal stability was determined by thermogravimetric analysis. Among the described materials, it was found that PMO with 10% imidazolium content is an effective host for the immobilization of perruthenate through an ion-exchange protocol. The resulting Ru@PI-10 was then employed as a recyclable catalyst in the highly efficient aerobic oxidation of various types of alcohols. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New Insight into the Reaction Mechanism for Exceptional Capacity of Ordered Mesoporous SnO2 Electrodes via Synchrotron-Based X-ray Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Hyunchul; Park, Gwi Ok; Kim, Yunok

2014-11-25

Tin oxide-based materials, operating via irreversible conversion and reversible alloying reaction, are promising lithium storage materials due to their higher capacity. Recent studies reported that nanostructured SnO2 anode provides higher capacity beyond theoretical capacity based on the alloying reaction mechanism; however, their exact mechanism remains still unclear. Here, we report the detailed lithium storage mechanism of an ordered mesoporous SnO2 electrode material. Synchrotron X-ray diffraction and absorption spectroscopy reveal that some portion of Li2O decomposes upon delithiation and the resulting oxygen reacts with Sn to form the SnOx phase along with dealloying of LixSn, which are the main reasons formore » unexpected high capacity of an ordered mesoporous SnO2 material. This finding will not only be helpful in a more complete understanding of the reaction mechanism of Sn-based oxide anode materials but also will offer valuable guidance for developing new anode materials with abnormal high capacity for next generation rechargeable batteries« less

Phenol-formaldehyde carbon with ordered/disordered bimodal mesoporous structure as high-performance electrode materials for supercapacitors

NASA Astrophysics Data System (ADS)

Cai, Tingwei; Zhou, Min; Han, Guangshuai; Guan, Shiyou

2013-11-01

A novel phenol-formaldehyde carbon with ordered/disordered bimodal mesoporous structure is synthesized by the facile evaporation induced self-assembly strategy under a basic aqueous condition with SiO2 particles as template. The prepared bimodal mesoporous carbons (BMCs) are composed of ordered mesoporous and disordered mesoporous with diameter of about 3.5 nm and 7.0 nm, respectively. They can be employed as supercapacitor electrodes in H2SO4 aqueous electrolyte after the simple acid-treatment. BMC exhibits an exceptional specific capacitance of 344 F g-1 at the current density of 0.1 A g-1, although it has a relatively low surface area of 722 m2 g-1. And the BMC electrode displays an excellent cycling stability over 10,000 cycles.

Conversion of kraft lignin over hierarchical MFI zeolite.

PubMed

Kim, Seong-Soo; Lee, Hyung Won; Ryoo, Ryong; Kim, Wookdong; Park, Sung Hoon; Jeon, Jong-Ki; Park, Young-Kwon

2014-03-01

Catalytic pyrolysis of kraft lignin was carried out using pyrolysis gas chromatography/mass spectrometry. Hierarchical mesoporous MFI was used as the catalyst and another mesoporous material Al-SBA-15 was also used for comparison. The characteristics of mesoporous MFI were analyzed by X-ray diffraction patterns, N2 adsorption-desorption isotherms, and temperature programmed desorption of NH3. Two catalyst/lignin mass ratios were tested: 5/1 and 10/1. Aromatics and alkyl phenolics were the main products of the catalytic pyrolysis of lignin over mesoporous MFI. In particular, the yields of mono-aromatics such as benzene, toluene, ethylbenzene, and xylene were increased substantially by catalytic upgrading. Increase in the catalyst dose enhanced the production of aromatics further, which is attributed to decarboxylation, decarbonlyation, and aromatization reactions occurring over the acid sites of mesoporous MFI.

Pair distribution function (PDF) analysis of mesoporous α-Fe2O3 and Cr2O3.

PubMed

Hill, Adrian H; Allieta, Mattia

2013-06-14

We have measured atomic pair distribution functions of novel mesoporous metal oxides, α-Fe2O3 and Cr2O3. These have an ordered pore mosaic as well as crystalline structure within the pore walls, making them an interesting class of materials to characterise. Comparison of "bulk" and mesoporous data sets has allowed an estimate of long range structural coherence to be derived; ≈125 Å and ≈290 Å for α-Fe2O3 and Cr2O3 respectively. Further "box-car" analysis has shown that above ≈40 Å both mesoporous samples deviate greatly from their bulk counterparts. This is attributed to the pores of the mesoporous structure creating voids in the pair-correlations, disrupting long range order.

Rational design of mesoporous metals and related nanomaterials by a soft-template approach.

PubMed

Yamauchi, Yusuke; Kuroda, Kazuyuki

2008-04-07

We review recent developments in the preparation of mesoporous metals and related metal-based nanomaterials. Among the many types of mesoporous materials, mesoporous metals hold promise for a wide range of potential applications, such as in electronic devices, magnetic recording media, and metal catalysts, owing to their metallic frameworks. Mesoporous metals with highly ordered networks and narrow pore-size distributions have traditionally been produced by using mesoporous silica as a hard template. This method involves the formation of an original template followed by deposition of metals within the mesopores and subsequent removal of the template. Another synthetic method is the direct-template approach from lyotropic liquid crystals (LLCs) made of nonionic surfactants at high concentrations. Direct-template synthesis creates a novel avenue for the production of mesoporous metals as well as related metal-based nanomaterials. Many mesoporous metals have been prepared by the chemical or electrochemical reduction of metal salts dissolved in aqueous LLC domains. As a soft template, LLCs are more versatile and therefore more advantageous than hard templates. It is possible to produce various nanostructures (e.g., lamellar, 2D hexagonal (p6mm), and 3D cubic (Ia\\3d)), nanoparticles, and nanotubes simply by controlling the composition of the reaction bath.

Peptide-laden mesoporous silica nanoparticles with promoted bioactivity and osteo-differentiation ability for bone tissue engineering.

PubMed

Luo, Zuyuan; Deng, Yi; Zhang, Ranran; Wang, Mengke; Bai, Yanjie; Zhao, Qiang; Lyu, Yalin; Wei, Jie; Wei, Shicheng

2015-07-01

Combination of mesoporous silica materials and bioactive factors is a promising niche-mimetic solution as a hybrid bone substitution for bone tissue engineering. In this work, we have synthesized biocompatible silica-based nanoparticles with abundant mesoporous structure, and incorporated bone-forming peptide (BFP) derived from bone morphogenetic protein-7 (BMP-7) into the mesoporous silica nanoparticles (MSNs) to obtain a slow-release system for osteogenic factor delivery. The chemical characterization demonstrates that the small osteogenic peptide is encapsulated in the mesoporous successfully, and the nitrogen adsorption-desorption isotherms suggest that the peptide encapsulation has no influence on mesoporous structure of MSNs. In the cell experiment, the peptide-laden MSNs (p-MSNs) show higher MG-63 cell proliferation, spreading and alkaline phosphatase (ALP) activity than the bare MSNs, indicating good in vitro cytocompatibility. Simultaneously, the osteogenesis-related proteins expression and calcium mineral deposition disclose enhanced osteo-differentiation of human mesenchymal stem cells (hMSCs) under the stimulation of the p-MSNs, confirming that BFP released from MSNs could significantly promote the osteogenic differentiation of hMSCs, especially at 500μg/mL of p-MSNs concentration. The peptide-modified MSNs with better bioactivity and osteogenic differentiation make it a potential candidate as bioactive material for bone repairing, bone regeneration, and bio-implant coating applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Kinetic and catalytic analysis of mesoporous Co3O4 on the oxidation of morin

NASA Astrophysics Data System (ADS)

Xaba, Morena. S.; Meijboom, Reinout

2017-11-01

Herein we report on the synthesis, characterization and catalytic evaluation of mesoporous cobalt oxides on the oxidation of morin. These mesoporous cobalt oxides were synthesized using an inverse surfactant micelle method, they are connected, well-defined with intra-particle voids. These materials were calcined to different final heating temperatures of 150, 250, 350, 450 and 550 °C, and each mesoporous cobalt oxide catalyst showed unique physical properties and catalytic behavior. Morin oxidation was used as a model reaction in the presence of hydrogen peroxide to evaluate the kinetic and catalytic activity of calcined mesoporous cobalt oxides. The adsorption-desorption equilibrium rate constants of morin and hydrogen peroxide were found to be inversely proportional to the crystallite size of the mesoporous cobalt oxide, and the characteristic path length in which the mass transfer takes place was found to be directly proportional to the crystallite size. The materials were characterized using powder X-Ray Diffraction (p-XRD), N2-sorption isotherms (BET), hydrogen temperature programmed reduction (H2-TPR) and High Resolution-Transmission Electron Microscopy (HR-TEM). UV-vis spectrophotometry was used to monitor the time-resolved absorbance of morin at λmax = 410 nm. The surface reaction in this system is described in terms of the well-established Langmuir-Hinshelwood model. The thermodynamic parameters, EA, ΔH#, ΔS# and ΔG# were calculated and catalyst recycling and reusability is demonstrated.

Highly hydrophilic poly(vinylidene fluoride)/meso-titania hybrid mesoporous membrane for photocatalytic membrane reactor in water

NASA Astrophysics Data System (ADS)

Wang, Meng; Yang, Guang; Jin, Peng; Tang, Hao; Wang, Huanhuan; Chen, Yong

2016-01-01

The high hydrophobicity of poly(vinylidene fluoride) (PVDF) membrane remains an obstacle to be applied in some purification processes of water or wastewater. Herein, a highly hydrophilic hybrid mesoporous titania membrane composed of mesoporous anatase titania (meso-TiO2) materials inside the three-dimensional (3D) macropores of PVDF membrane was successfully prepared by using the dual-templated synthesis method combined with solvent extraction and applied as the photocatalytic membrane reactor for the photodegredation of organic dye in water. The structure and the properties of as-prepared hybrid membranes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen adsorption-desorption and contact angle measurements. It was found that the hydrophilicity of PVDF membrane can be significantly improved by filling mesoporous TiO2 inside the 3D macropores of PVDF membrane. Moreover, such a PVDF/meso-TiO2 hybrid membrane exhibits promising photocatalytic degradation of dye in water due to the existence of mesoporous anatase TiO2 materials inside PVDF membrane. This study provides a new strategy to simultaneously introduce hydrophilicity and some desirable properties into PVDF and other hydrophobic membranes.

Direct synthesis of graphitic mesoporous carbon from green phenolic resins exposed to subsequent UV and IR laser irradiations

PubMed Central

Sopronyi, Mihai; Sima, Felix; Vaulot, Cyril; Delmotte, Luc; Bahouka, Armel; Matei Ghimbeu, Camelia

2016-01-01

The design of mesoporous carbon materials with controlled textural and structural features by rapid, cost-effective and eco-friendly means is highly demanded for many fields of applications. We report herein on the fast and tailored synthesis of mesoporous carbon by UV and IR laser assisted irradiations of a solution consisting of green phenolic resins and surfactant agent. By tailoring the UV laser parameters such as energy, pulse repetition rate or exposure time carbon materials with different pore size, architecture and wall thickness were obtained. By increasing irradiation dose, the mesopore size diminishes in the favor of wall thickness while the morphology shifts from worm-like to an ordered hexagonal one. This was related to the intensification of phenolic resin cross-linking which induces the reduction of H-bonding with the template as highlighted by 13C and 1H NMR. In addition, mesoporous carbon with graphitic structure was obtained by IR laser irradiation at room temperature and in very short time periods compared to the classical long thermal treatment at very high temperatures. Therefore, the carbon texture and structure can be tuned only by playing with laser parameters, without extra chemicals, as usually required. PMID:28000781

Synthesis and characterization of amorphous mesoporous silica using TEMPO-functionalized amphiphilic templates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vries, Wilke de; Doerenkamp, Carsten; Zeng, Zhaoyang

Inorganic–organic hybrid materials based on amorphous mesoporous silica containing organized nitroxide radicals within its mesopores have been prepared using the micellar self-assembly of TEOS solutions containing the nitroxide functionalized amphiphile (4-(N,N-dimethyl-N-hexadecylammonium)-2,2,6, 6-tetramethyl-piperidin-N-oxyl-iodide) (CAT-16). This template has been used both in its pure form and in various mixtures with cetyl trimethylammonium bromide (CTAB). The samples have been characterized by chemical analysis, N{sub 2} sorption studies, magnetic susceptibility measurements, and various spectroscopic methods. While electron paramagnetic resonance (EPR) spectra indicate that the strength of the intermolecular spin–spin interactions can be controlled via the CAT-16/CTAB ratio, nuclear magnetic resonance (NMR) data suggest thatmore » these interactions are too weak to facilitate cooperative magnetism. - Graphical abstract: The amphiphilic radical CAT-16 is used as a template for the synthesis of amorphous mesoporous silica. The resulting paramagnetic hybrid materials are characterized by BET, FTIR, NMR, EPR and magnetic susceptibility studies. - Highlights: • Amphiphilic CAT-16 as a template for mesoporous silica. • Comprehensive structural characterization by BET, FTIR; EPR and NMR. • Strength of radical-radical interactions tuable within CAT-16/CTAB mixtures.« less

Materials with engineered mesoporosity for programmed mass transport

NASA Astrophysics Data System (ADS)

Gough, Dara V.

Transport in nanostructured materials is of great interest for scientists in various fields, including molecular sequestration, catalysis, artificial photosynthesis and energy storage. This thesis will present work on the transport of molecular and ionic species in mesoporous materials (materials with pore sizes between 2 and 50 nm). Initially, discussion will focus on the synthesis of mesoporous ZnS nanorattles and the size selected mass transport of small molecules through the mesopores. Discussion will then shift of exploration of cation exchange and electroless plating of metals to alter the mesoporous hollow sphere (MHS) materials and properties. The focus of discussion will then shift to the transport of ions into and out of a hierarchically structured gold electrode. Finally, a model gamma-bactiophage was developed to study the electromigration of charged molecules into and out of a confined geometry. A catalytically active biomolecular species was encapsulated within the central cavity of ZnS MHS. Both the activity of the encapsulated enzyme and the size-selective transport through the wall of the MHS were verified through the use of a common fluorogen, hydrogen peroxide, and sodium azide. Additionally, the protection of the enzyme was shown through size-selected blocking of a protease. The mesoporous hollow sphere system introduces size-selectivity to catalyzed chemical reactions; future work may include variations in pore sizes, and pore wall chemical functionalization. The pore size in ZnS mesoporous hollow spheres is controlled between 2.5 and 4.1 nm through swelling of the lyotropic liquid crystal template. The incorporation of a swelling agent is shown to linearly vary the hexagonal lyotropic liquid crystalline phase, which templates the mesopores, while allowing the high fidelity synthesis of mesoporous hollow spheres. Fluorescnently labeled ssDNA was utilized as a probe to explore the change in mesopore permeability afforded by the swollen template relative to the unswollen template. Electroless plating and cation exchange were explored as methods to vary the shell material of MHS. Mesoporous Ni MHS were obtained by the reduction of Ni2+ with dimethylamine borane onto a CML latex core. However, the resultant MHS were damaged due to core swelling during etch. To successfully obtain undeformed MHS, a silica core must be utilized; one possible route to explore, in order to reach this goal, is the surface chemistry/ligand effects on Ni2+. Cation exchange was performed in order to obtain CuS MHS; however, it proved an unsuccessful route to PbS, S and HgS. CdS-ZnS, Bi2S3 and Ag2S MHS were obtained only with significant defects. A novel hierarchically structured material, porous opal, was prepared using a colloidal crystal template and the dealloying of silver from gold and possed porosity on length scales range from 10s of nanometers (due to the colloidal crystal template) down to ca. 10 nm (due to dealloying). The transport properties of the material were studied using cyclic voltammetry and electrochemical impedance spectroscopy. The porous opal was found to posses enhanced charge transport properties relative to a unimodal porous gold film and a higher surface area than a gold opal. An equivalent circuit model was presented to explain the enhanced charge transport properties. A biomimetic system for studying the translocation of polymers through a channel and into a spherical cavity was developed based on inspiration from the gamma-bacteriophage. The nanocavity system was synthesized using two template length scales: 250 nm and 1.2 mum. Fabrication challenges that arose when using 1.2 mum colloidal templates were addressed, and the system was optimized for confinement studies of plasmid dsDNA.

Tailored Design of Bicontinuous Gyroid Mesoporous Carbon and Nitrogen-Doped Carbon from Poly(ethylene oxide-b-caprolactone) Diblock Copolymers.

PubMed

Chu, Wei-Cheng; Bastakoti, Bishnu Prasad; Kaneti, Yusuf Valentino; Li, Jheng-Guang; Alamri, Hatem R; Alothman, Zeid A; Yamauchi, Yusuke; Kuo, Shiao-Wei

2017-10-04

Highly ordered mesoporous resol-type phenolic resin and the corresponding mesoporous carbon materials were synthesized by using poly(ethylene oxide-b-caprolactone) (PEO-b-PCL) diblock copolymer as a soft template. The self-assembled mesoporous phenolic resin was found to form only in a specific resol concentration range of 40-70 wt % due to an intriguing balance of hydrogen-bonding interactions in the resol/PEO-b-PCL mixtures. Furthermore, morphological transitions of the mesostructures from disordered to gyroid to cylindrical and finally to disordered micelle structure were observed with increasing resol concentration. By calcination under nitrogen atmosphere at 800 °C, the bicontinuous mesostructured gyroid phenolic resin could be converted to mesoporous carbon with large pore size without collapse of the original mesostructure. Furthermore, post-treatment of the mesoporous gyroid phenolic resin with melamine gave rise to N-doped mesoporous carbon with unique electronic properties for realizing high CO 2 adsorption capacity (6.72 mmol g -1 at 0 °C). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mesoporous LiFeBO3/C hollow spheres for improved stability lithium-ion battery cathodes

NASA Astrophysics Data System (ADS)

Chen, Zhongxue; Cao, Liufei; Chen, Liang; Zhou, Haihui; Zheng, Chunman; Xie, Kai; Kuang, Yafei

2015-12-01

Polyanionic compounds are regarded as one of the most promising cathode materials for the next generation lithium-ion batteries due to their abundant resource and thermal stability. LiFeBO3 has a relatively higher capacity than olivine LiFePO4, however, moisture sensitivity and low conductivity hinder its further development. Here, we design and synthesize mesoporous LiFeBO3/C (LFB/C) hollow spheres to enhance its structural stability and electric conductivity, two LiFeBO3/C electrodes with different carbon content are prepared and tested. The experimental results show that mesoporous LiFeBO3/C hollow spheres with higher carbon content exhibit superior lithium storage capacity, cycling stability and rate capability. Particularly, the LFB/C electrode with higher carbon content demonstrates good structural stability, which can maintain its original crystal structure and Li storage properties even after three months of air exposure at room temperature. The exceptional structural stability and electrochemical performance may justify their potential use as high-performance cathode materials for advanced lithium-ion batteries. In addition, the synthesis strategy demonstrated herein is simple and versatile for the fabrication of other polyanionic cathode materials with mesoporous hollow spherical structure.

Amorphous Mn oxide-ordered mesoporous carbon hybrids as a high performance electrode material for supercapacitors.

PubMed

Nam, Inho; Kim, Nam Dong; Kim, Gil-Pyo; Park, Junsu; Yi, Jongheop

2012-07-01

A supercapacitor has the advantages of both the conventional capacitors and the rechargeable batteries. Mn oxide is generally recognized one of the potential materials that can be used for a supercapacitor, but its low conductivity is a limiting factor for electrode materials. In this study, a hybrid of amorphous Mn oxide (AMO) and ordered mesoporous carbon (OMC) was prepared and characterized using X-ray diffraction, transmission electron microscopy, N2/77 K sorption techniques, and electrochemical analyses. The findings indicate that the electrochemical activities of Mn oxide were facilitated when it was in the hybrid state because OMC acted as a pathway for both the electrolyte ions and the electrons due to the characteristics of the ordered mesoporous structure. The ordered mesoporous structure of OMC was well maintained even after hybridization with amorphous Mn oxide. The electrochemical-activity tests revealed that the AMO/OMC hybrid had a higher specific capacitance and conductivity than pure Mn oxide. In the case where the Mn/C weight ratio was 0.75, the composite showed a high capacitance of 153 F/g, which was much higher than that for pure Mn oxide, due to the structural effects of OMC.

Mesoporous MnO2/carbon aerogel composites as promising electrode materials for high-performance supercapacitors.

PubMed

Li, Gao-Ren; Feng, Zhan-Ping; Ou, Yan-Nan; Wu, Dingcai; Fu, Ruowen; Tong, Ye-Xiang

2010-02-16

MnO(2) as one of the most promising candidates for electrochemical supercapacitors has attracted much attention because of its superior electrochemical performance, low cost, and environmentally benign nature. In this Letter, we explored a novel route to prepare mesoporous MnO(2)/carbon aerogel composites by electrochemical deposition assisted by gas bubbles. The products were characterized by energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The MnO(2) deposits are found to have high purity and have a mesoporous structure that will optimize the electronic and ionic conductivity to minimize the total resistance of the system and thereby maximize the performance characteristics of this material for use in supercapacitor electrodes. The results of nitrogen adsorption-desorption experiments and electrochemical measurements showed that these obtained mesoporous MnO(2)/carbon aerogel composites had a large specific surface area (120 m(2)/g), uniform pore-size distribution (around 5 nm), high specific capacitance (515.5 F/g), and good stability over 1000 cycles, which give these composites potential application as high-performance supercapacitor electrode materials.

Fabrication of Meso-Porous Sintered Metal Thin Films by Selective Etching of Silica Based Sacrificial Template

PubMed Central

Dumée, Ludovic F.; She, Fenghua; Duke, Mikel; Gray, Stephen; Hodgson, Peter; Kong, Lingxue

2014-01-01

Meso-porous metal materials have enhanced surface energies offering unique surface properties with potential applications in chemical catalysis, molecular sensing and selective separation. In this paper, commercial 20 nm diameter metal nano-particles, including silver and copper were blended with 7 nm silica nano-particles by shear mixing. The resulted powders were cold-sintered to form dense, hybrid thin films. The sacrificial silica template was then removed by selective etching in 12 wt% hydrofluoric acid solutions for 15 min to reveal a purely metallic meso-porous thin film material. The impact of the initial silica nano-particle diameter (7–20 nm) as well as the sintering pressure (5–20 ton·m−2) and etching conditions on the morphology and properties of the final nano-porous thin films were investigated by porometry, pyknometery, gas and liquid permeation and electron microscopy. Furthermore, the morphology of the pores and particle aggregation during shear mixing were assessed through cross-sectioning by focus ion beam milling. It is demonstrated that meso-pores ranging between 50 and 320 nm in average diameter and porosities up to 47% can be successfully formed for the range of materials tested. PMID:28344241

Recent development, applications, and perspectives of mesoporous silica particles in medicine and biotechnology.

PubMed

Pasqua, Luigi; Cundari, Sante; Ceresa, Cecilia; Cavaletti, Guido

2009-01-01

Mesoporous silica particles (MSP) are a new development in nanotechnology. Covalent modification of the surface of the silica is possible both on the internal pore and on the external particle surface. It allows the design of functional nanostructured materials with properties of organic, biological and inorganic components. Research and development are ongoing on the MSP, which have applications in catalysis, drug delivery and imaging. The most recent and interesting advancements in size, morphology control and surface functionalization of MSP have enhanced the biocompatibility of these materials with high surface areas and pore volumes. In the last 5 years several reports have demonstrated that MSP can be efficiently internalized using in vitro and animal models. The functionalization of MSP with organic moieties or other nanostructures brings controlled release and molecular recognition capabilities to these mesoporous materials for drug/gene delivery and sensing applications, respectively. Herein, we review recent research progress on the design of functional MSP materials with various mechanisms of targeting and controlled release.

Mesoporous MnCo2O4 with a flake-like structure as advanced electrode materials for lithium-ion batteries and supercapacitors.

PubMed

Mondal, Anjon Kumar; Su, Dawei; Chen, Shuangqiang; Ung, Alison; Kim, Hyun-Soo; Wang, Guoxiu

2015-01-19

A mesoporous flake-like manganese-cobalt composite oxide (MnCo2O4) is synthesized successfully through the hydrothermal method. The crystalline phase and morphology of the materials are characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmett-Teller methods. The flake-like MnCo2O4 is evaluated as the anode material for lithium-ion batteries. Owing to its mesoporous nature, it exhibits a high reversible capacity of 1066 mA h g(-1), good rate capability, and superior cycling stability. As an electrode material for supercapacitors, the flake-like MnCo2O4 also demonstrates a high supercapacitance of 1487 F g(-1) at a current density of 1 A g(-1), and an exceptional cycling performance over 2000 charge/discharge cycles. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-assembly of supramolecular triarylamine nanowires in mesoporous silica and biocompatible electrodes thereof.

PubMed

Licsandru, Erol-Dan; Schneider, Susanne; Tingry, Sophie; Ellis, Thomas; Moulin, Emilie; Maaloum, Mounir; Lehn, Jean-Marie; Barboiu, Mihail; Giuseppone, Nicolas

2016-03-14

Biocompatible silica-based mesoporous materials, which present high surface areas combined with uniform distribution of nanopores, can be organized in functional nanopatterns for a number of applications. However, silica is by essence an electrically insulating material which precludes applications for electro-chemical devices. The formation of hybrid electroactive silica nanostructures is thus expected to be of great interest for the design of biocompatible conducting materials such as bioelectrodes. Here we show that we can grow supramolecular stacks of triarylamine molecules in the confined space of oriented mesopores of a silica nanolayer covering a gold electrode. This addressable bottom-up construction is triggered from solution simply by light irradiation. The resulting self-assembled nanowires act as highly conducting electronic pathways crossing the silica layer. They allow very efficient charge transfer from the redox species in solution to the gold surface. We demonstrate the potential of these hybrid constitutional materials by implementing them as biocathodes and by measuring laccase activity that reduces dioxygen to produce water.

Low temperature biosynthesis of Li2O-MgO-P2O5-TiO2 nanocrystalline glass with mesoporous structure exhibiting fast lithium ion conduction.

PubMed

Du, Xiaoyong; He, Wen; Zhang, Xudong; Ma, Jinyun; Wang, Chonghai; Li, Chuanshan; Yue, Yuanzheng

2013-04-01

We demonstrate a biomimetic synthesis methodology that allows us to create Li2O-MgO-P2O5-TiO2 nanocrystalline glass with mesoporous structure at lower temperature. We design a 'nanocrystal-glass' configuration to build a nanoarchitecture by means of yeast cell templates self-assembly followed by the controlled in-situ biomineralization of materials on the cell wall. Electrochemically active nanocrystals are used as the lamellar building blocks of mesopores, and the semiconductive glass phase can act both as the 'glue' between nanocrystals and functionalized component. The Li2O-MgO-P2O5-TiO2 nanocrystalline glass exhibits outstanding thermal stability, high conductivity and wide potential window. This approach could be applied to many other multicomponent glass-ceramics to fabricate mesoporous conducting materials for solid-state lithium batteries. Copyright © 2012 Elsevier B.V. All rights reserved.

Aminopropyl-functionalized ethane-bridged periodic mesoporous organosilica spheres: preparation and application in liquid chromatography.

PubMed

Li, Chun; Di, Bin; Hao, Weiqiang; Yan, Fang; Su, Mengxiang

2011-01-21

A synthetic approach for synthesizing spherical aminopropyl-functionalized ethane-bridged periodic mesoporous organosilicas (APEPMOs) is reported. The mesoporous material was prepared by a one-step co-condensation of 1,2-bis(triethoxysilyl)ethane (BTSE) and 3-aminopropyltriethoxysilane (APTES) using cetyltrimethylammonium chlorine (C(18)TACl) as a template with the aid of a co-solvent (methanol) in basic medium. The APEPMOs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD), nitrogen sorption measurement, Fourier transform infrared spectroscopy (FT-IR) and elemental analysis. It was shown that this material exhibited spherical morphology, ordered cubic mesostructure and good mechanical strength. The APEPMOs were tested as a potential stationary phase for liquid chromatography (LC) because the column exhibited reduced back pressure. Moreover, they exhibited good chemical stability in basic mobile phase, which can be ascribed to the ethane groups in the mesoporous framework. Copyright © 2010 Elsevier B.V. All rights reserved.

Assessment of surface acidity in mesoporous materials containing aluminum and titanium

NASA Astrophysics Data System (ADS)

Araújo, Rinaldo S.; Maia, Débora A. S.; Azevedo, Diana C. S.; Cavalcante, Célio L., Jr.; Rodríguez-Castellón, E.; Jimenez-Lopez, A.

2009-04-01

The surface acidity of mesoporous molecular sieves of aluminum and titanium was evaluated using four different techniques: n-butylamine volumetry, cyclohexylamine thermodesorption, temperature-programmed desorption of ammonia and adsorption of pyridine. The nature, strength and concentration of the acid sites were determined and correlated to the results of a probe reaction of anthracene oxidation to 9,10-anthraquinone (in liquid phase). In general, the surface acidity was highly influenced by the nature, location and coordination of the metal species (Al and Ti) in the mesoporous samples. Moderate to strong Brönsted acid sites were identified for the Al-MCM-41 sample in a large temperature range. For mesoporous materials containing Ti, the acidity was represented by a combination of weak to moderate Brönsted and Lewis acid sites. The Ti-HMS sample exhibits a higher acidity of moderate strength together with a well-balanced concentration of Brönsted and Lewis acid sites, which enhanced both conversion and selectivity in the oxidation reaction of anthracene.

Wet powder processing of sol-gel derived mesoporous silica-hydroxyapatite hybrid powders.

PubMed

Andersson, Jenny; Johannessen, Espen; Areva, Sami; Järn, Mikael; Lindén, Mika

2006-08-01

This paper describes a method by which a porous silica coating layer can be obtained on different apatite particles through a simple sol-gel synthesis route. Sol-gel derived powders of hydroxyapatite (HAP) and beta tricalciumphosphate (beta-TCP) were coated with a mesoporous silica using C16TAB (hexadecyltrimethylammonium bromide) as a template in order to induce mesophase formation. Further calcination of the material removes the template from the mesophase and leaves a highly ordered hexagonal arranged mesoporous silica structure with a core of HAP/beta-TCP. The phase purity of the SiO2/apatite composites has been thoroughly investigated by the means of FT-IR, XRD, and solid state 31P MAS NMR. The phase purity of these materials is shown to be dependent on the solubility properties of the used apatites. The hybrid materials are suitable as a multifunctional biomaterial where osteoconductive properties can be combined with drug delivery.

Preparation and Electrochemical Characterization of Mesoporous Polyaniline-Silica Nanocomposites as an Electrode Material for Pseudocapacitors

PubMed Central

Zu, Lei; Cui, Xiuguo; Jiang, Yanhua; Hu, Zhongkai; Lian, Huiqin; Liu, Yang; Jin, Yushun; Li, Yan; Wang, Xiaodong

2015-01-01

Mesoporous polyaniline-silica nanocomposites with a full interpenetrating structure for pseudocapacitors were synthesized via the vapor phase approach. The morphology and structure of the nanocomposites were deeply investigated by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis and nitrogen adsorption-desorption tests. The results present that the mesoporous nanocomposites possess a uniform particle morphology and full interpenetrating structure, leading to a continuous conductive polyaniline network with a large specific surface area. The electrochemical performances of the nanocomposites were tested in a mixed solution of sulfuric acid and potassium iodide. With the merits of a large specific surface area and suitable pore size distribution, the nanocomposite showed a large specific capacitance (1702.68 farad (F)/g) due to its higher utilization of the active material. This amazing value is almost three-times larger than that of bulk polyaniline when the same mass of active material was used. PMID:28788006

Mg-MOF-74@SBA-15 hybrids: Synthesis, characterization, and adsorption properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborty, Anindita; Maji, Tapas Kumar, E-mail: tmaji@jncasr.ac.in

2014-12-01

Nanocrystals of Mg-MOF-74 have been immobilized into the mesopores of SBA-15 rods to fabricate Mg-MOF-74@SBA-15 hybrid materials. To furnish such composites, a relatively simple synthetic strategy has been adopted by direct dispersion of the metal-organic framework (MOF) precursors in SBA-15 matrix to prepare the hybrid materials in situ. The hybrid materials have been characterized using powder X-ray diffraction and several spectroscopic and microscopic techniques, which suggest growth of the MOF nanocrystals inside the SBA-15 mesopores and the composites exhibit characteristics of both the components. N{sub 2} adsorption isotherms at 77 K reveal that the composites contain additional mesopores, compared tomore » only micropores of pristine MOF nanocrystals. In addition to such combination of both micro and mesoporosity, the composites also demonstrate significant CO{sub 2} adsorption at room temperature.« less

Key factor affecting the structural and textural properties of ZSM-5/MCM-41 composite

NASA Astrophysics Data System (ADS)

Boukoussa, Bouhadjar; Aouad, Nafissa; Hamacha, Rachida; Bengueddach, Abdelkader

2015-03-01

ZSM-5/MCM-41 micro/mesoporous composite materials were synthesized by the hydrothermal technique with alkali-treated ZSM-5 zeolite as source of silica and aluminum and characterized by various physico-chemical techniques such as X-ray diffraction (XRD), nitrogen sorption at 77 K, transmission electronic microscopy (TEM), FTIR spectroscopy and NH3 temperature programmed desorption (TPD) techniques. The effect of concentration of CTAB in the synthesis of these solids has been investigated, the mesopore volume, surface area and surface acidity decrease with increasing the concentration of CTAB. Increasing the CTAB concentration causes the recrystallization of zeolite ZSM-5 and it disadvantage the formation of mesoporous materials MCM-41. The catalytic activity of ZSM-5/MCM-41 materials has been evaluated in the Friedel-Crafts acylation of anisole with benzoyl chloride as alkylating agent. The results revealed the reaction to be influenced by surface area, pore volume and surface acidity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tong Dongge; Han Xue; Chu Wei

Co-B flowers with mesoporous structure were first prepared via reduction of cobalt acetate by potassium borohydride in the presence of complexing agent ethylenediamine. The as-prepared Co-B flowers were characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, N{sub 2} adsorption-desorption, and magnetic performance test. The Co-B flowers exhibited enhanced coercivity, and weakened saturation magnetization and remanet magnetization as compared with the regular Co-B. During the hydrolysis of KBH{sub 4}, the Co-B flowers exhibited higher catalytic activity than the regular Co-B. It is attributed to themore » larger specific surface area and mesoporous channels. During the successive reactions, the conversion of KBH{sub 4} over Co-B flowers was about 97%. The average H{sub 2} generation rate of Co-B flowers was 4620 mL/min/g-catalyst in 1.5 wt% NaOH + 15 wt% KBH{sub 4} solution, which may give a successive H{sub 2} supply for a 748 W polymer electrolyte membrane fuel cell (PEMFC) at 100% H{sub 2} utilization.« less

Hydrodeoxygenation of Pyrolysis Bio-Oil Over Ni Impregnated Mesoporous Materials.

PubMed

Lee, In-Gu; Lee, Heejin; Kang, Bo Sung; Kim, Young-Min; Kim, Sang Chai; Jung, Sang-Chul; Ko, Chang Hyun; Park, Young-Kwon

2018-02-01

The catalytic hydrodeoxygenation (HDO) of bio-oil over Ni-supported mesoporous materials was performed using a high pressure autoclave reactor. The actual pyrolysis oil of cork oak wood was used as a sample, and Ni/Al-SBA-15 and Ni/Al-MSU-F were used as catalysts. In addition, supercritical ethanol was added as solvent. Both Ni-supported mesoporous catalysts showed efficient HDO reaction ability. A higher heating value and pH of bio-oil were achieved by the HDO reaction over both catalysts and upgraded bio-oil had a lower viscosity. Compared to Ni/Al-MSU-F, Ni/Al- SBA-15 produced more upgraded bio-oil with a lower oxygen content and higher heating value via a catalytic HDO process.

Mesoporous aluminium organophosphonates: a reusable chemsensor for the detection of explosives

NASA Astrophysics Data System (ADS)

Li, Dongdong; Yu, Xiang

2016-07-01

Rapid and sensitive detection of explosives is in high demand for homeland security and public safety. In this work, electron-rich of anthracene functionalized mesoporous aluminium organophosphonates (En-AlPs) were synthesized by a one-pot condensation process. The mesoporous structure and strong blue emission of En-AlPs were confirmed by the N2 adsorption-desorption isotherms, transmission electron microscopy images and fluorescence spectra. The materials En-AlPs can serve as sensitive chemosensors for various electron deficient nitroderivatives, with the quenching constant and the detection limit up to 1.5×106 M-1 and 0.3 ppm in water solution. More importantly, the materials can be recycled for many times by simply washed with ethanol, showing potential applications in explosives detection.

Facile synthesis of Mesoporouscobalt Hexacyanoferrate Nanocubes for High-Performance Supercapacitors

PubMed Central

2017-01-01

Mesoporous cobalt hexacyanoferrate nanocubes (meso–CoHCF) were prepared for the first time through a facile sacrificial template method. The CoHCF mesostructures possess a high specific surface area of 548.5 m2·g−1 and a large amount of mesopores, which enable fast mass transport of electrolyte and abundant energy storage sites. When evaluated as supercapacitor materials, the meso–CoHCF materials exhibit a high specific capacitance of 285 F·g−1, good rate capability and long cycle life with capacitance retention of 92.9% after 3000 cycles in Na2SO4 aqueous electrolyte. The excellent electrochemical properties demonstrate the rational preparation of mesoporous prussian blue and its analogues for energy storage applications. PMID:28825671

Structured mesoporous Mn, Fe, and Co oxides: Synthesis, physicochemical, and catalytic properties

NASA Astrophysics Data System (ADS)

Maerle, A. A.; Karakulina, A. A.; Rodionova, L. I.; Moskovskaya, I. F.; Dobryakova, I. V.; Egorov, A. V.; Romanovskii, B. V.

2014-02-01

Structured mesoporous Mn, Fe, and Co oxides are synthesized using "soft" and "hard" templates; the resulting materials are characterized by XRD, SEM, TEM, BET, and TG. It is shown that in the first case, the oxides have high surface areas of up to 450 m2/g that are preserved after calcination of the material up to 300°C. Even though, the surface area of the oxides prepared by the "hard-template" method does not exceed 100 m2/g; it is, however, thermally stable up to 500°C. Catalytic activity of mesoporous oxides in methanol conversion was found to depend on both the nature of the transition metal and the type of template used in synthesis.

Continuous mesoporous titania nanocrystals: their growth in confined space and scope for application.

PubMed

Dutta, Saikat; Bhaumik, Asim

2013-11-01

Enjoying the single lifestyle: With an overwhelming efficiency compared to thermally sintered preformed nanocrystals, mesoporous single crystals (MSCs) of TiO2 constitute a new class of semiconductor materials for low-cost solar power, solar fuel, photocatalysis, and energy storage applications. This Highlight explores the benefits of template-directed seed-mediated growth in the confined space of a preseeded mesoporous template, and possible research avenues for further improvements. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Exploring Mass Transfer in Mesoporous Zeolites by NMR Diffusometry

PubMed Central

Mehlhorn, Dirk; Valiullin, Rustem; Kärger, Jörg; Cho, Kanghee; Ryoo, Ryong

2012-01-01

With the advent of mesoporous zeolites, the exploration of their transport properties has become a task of primary importance for the auspicious application of such materials in separation technology and heterogeneous catalysis. After reviewing the potential of the pulsed field gradient method of NMR (PFG NMR) for this purpose in general, in a case study using a specially prepared mesoporous zeolite NaCaA as a host system and propane as a guest molecule, examples of the attainable information are provided. PMID:28817004

Location of laccase in ordered mesoporous materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayoral, Álvaro; Gascón, Victoria; Blanco, Rosa M.

2014-11-01

The functionalization with amine groups was developed on the SBA-15, and its effect in the laccase immobilization was compared with that of a Periodic Mesoporous Aminosilica. A method to encapsulate the laccase in situ has now been developed. In this work, spherical aberration (C{sub s}) corrected scanning transmission electron microscopy combined with high angle annular dark field detector and electron energy loss spectroscopy were applied to identify the exact location of the enzyme in the matrix formed by the ordered mesoporous solids.

Location of laccase in ordered mesoporous materials

NASA Astrophysics Data System (ADS)

Mayoral, Álvaro; Gascón, Victoria; Blanco, Rosa M.; Márquez-Álvarez, Carlos; Díaz, Isabel

2014-11-01

The functionalization with amine groups was developed on the SBA-15, and its effect in the laccase immobilization was compared with that of a Periodic Mesoporous Aminosilica. A method to encapsulate the laccase in situ has now been developed. In this work, spherical aberration (Cs) corrected scanning transmission electron microscopy combined with high angle annular dark field detector and electron energy loss spectroscopy were applied to identify the exact location of the enzyme in the matrix formed by the ordered mesoporous solids.

Self-assembly of supramolecular triarylamine nanowires in mesoporous silica and biocompatible electrodes thereof

NASA Astrophysics Data System (ADS)

Licsandru, Erol-Dan; Schneider, Susanne; Tingry, Sophie; Ellis, Thomas; Moulin, Emilie; Maaloum, Mounir; Lehn, Jean-Marie; Barboiu, Mihail; Giuseppone, Nicolas

2016-03-01

Biocompatible silica-based mesoporous materials, which present high surface areas combined with uniform distribution of nanopores, can be organized in functional nanopatterns for a number of applications. However, silica is by essence an electrically insulating material which precludes applications for electro-chemical devices. The formation of hybrid electroactive silica nanostructures is thus expected to be of great interest for the design of biocompatible conducting materials such as bioelectrodes. Here we show that we can grow supramolecular stacks of triarylamine molecules in the confined space of oriented mesopores of a silica nanolayer covering a gold electrode. This addressable bottom-up construction is triggered from solution simply by light irradiation. The resulting self-assembled nanowires act as highly conducting electronic pathways crossing the silica layer. They allow very efficient charge transfer from the redox species in solution to the gold surface. We demonstrate the potential of these hybrid constitutional materials by implementing them as biocathodes and by measuring laccase activity that reduces dioxygen to produce water.Biocompatible silica-based mesoporous materials, which present high surface areas combined with uniform distribution of nanopores, can be organized in functional nanopatterns for a number of applications. However, silica is by essence an electrically insulating material which precludes applications for electro-chemical devices. The formation of hybrid electroactive silica nanostructures is thus expected to be of great interest for the design of biocompatible conducting materials such as bioelectrodes. Here we show that we can grow supramolecular stacks of triarylamine molecules in the confined space of oriented mesopores of a silica nanolayer covering a gold electrode. This addressable bottom-up construction is triggered from solution simply by light irradiation. The resulting self-assembled nanowires act as highly conducting electronic pathways crossing the silica layer. They allow very efficient charge transfer from the redox species in solution to the gold surface. We demonstrate the potential of these hybrid constitutional materials by implementing them as biocathodes and by measuring laccase activity that reduces dioxygen to produce water. Electronic supplementary information (ESI) available: Synthetic protocols, XPS measurements, contact angle measurements, additional cyclic voltammograms and electrochemical impedance spectroscopy. See DOI: 10.1039/c5nr06977g

Chemistry of alkali cation exchanged faujasite and mesoporous NaX using alkyl halides and phosphates

NASA Astrophysics Data System (ADS)

Lee, Min-Hong

The purpose of this work was to increase the reactivity of Faujasite X (NaX) zeolite toward the reactive decontamination of materials subject to nucleophilic attack by means of zeolite cation optimization and by means of the synthesis of mesoporous Faujasite X. Primary alkyl halides and trialkyl phosphates have been the test materials on which the cation-optimized and mesoporous zeolites have been tested. In the alkali cation optimization work, reactions of methyl iodide and 1-chloropropane with alkali metal cation exchanged Faujasite zeolite X were investigated at room temperature. The reactivity of the framework and the product formation were shown to depend on zeolite framework counter-cation. A quantitative study of zeolite product formation has been carried out, primarily using solid-state NMR spectroscopy. Large alkali cations showed preference toward substitution chemistry. In contrast, alkyl halide exposed LiX and NaX zeolites underwent both substitution and elimination. Subsequently introduced water molecules led to hydrolysis of framework species that was sensitive to framework counter-cation. The mesoporous NaX zeolites work undertakes to test whether an improvement in surface chemical reactivity can be achieved by introducing mesopores into the already reactive nucleophilic microporous NaX zeolite. Incorporation of the polydiallyl dimethyl ammonium chloride (PDADMAC) template and the formation of mesopores in Faujasite X zeolite (NaX) were successful and well-characterized. The mesopores are proposed to have occurred from incorporation of the cationic PDADMAC polymer into the zeolite by compensating zeolite framework charge. Subsequent sodium cation exchange of calcined mesoporous NaX was shown to restore the chemical reactivity characteristic of as-synthesized NaX. Trialkyl organophosphorous compounds underwent substitution reactions. The reactivity of both microporous and mesoporous Faujasite zeolite X and the product formation was shown to depend on the length of the alkyl chain. Although introduced mesopores alleviated the limited reagent diffusion to reactive sites due to the microporosity of the NaX zeolites, no marked improvement in the product yields was achieved with either the 1-chloroalkanes or the trialkyl phosphates test compounds, regardless of alkyl chain length. The disappointing results have been attributed to lack of substantial net increase in the numbers of zeolite nucleophilic sites accompanying mesopore introduction.

Amorphous ZnO Quantum Dot/Mesoporous Carbon Bubble Composites for a High-Performance Lithium-Ion Battery Anode.

PubMed

Tu, Zhiming; Yang, Gongzheng; Song, Huawei; Wang, Chengxin

2017-01-11

Due to its high theoretical capacity (978 mA h g -1 ), natural abundance, environmental friendliness, and low cost, zinc oxide is regarded as one of the most promising anode materials for lithium-ion batteries (LIBs). A lot of research has been done in the past few years on this topic. However, hardly any research on amorphous ZnO for LIB anodes has been reported despite the fact that the amorphous type could have superior electrochemical performance due to its isotropic nature, abundant active sites, better buffer effect, and different electrochemical reaction details. In this work, we develop a simple route to prepare an amorphous ZnO quantum dot (QDs)/mesoporous carbon bubble composite. The composite consists of two parts: mesoporous carbon bubbles as a flexible skeleton and monodisperse amorphous zinc oxide QDs (smaller than 3 nm) encapsulated in an amorphous carbon matrix as a continuous coating tightly anchored on the surface of mesoporous carbon bubbles. With the benefits of abundant active sites, amorphous nature, high specific surface area, buffer effect, hierarchical pores, stable interconnected conductive network, and multidimensional electron transport pathways, the amorphous ZnO QD/mesoporous carbon bubble composite delivers a high reversible capacity of nearly 930 mA h g -1 (at current density of 100 mA g -1 ) with almost 90% retention for 85 cycles and possesses a good rate performance. This work opens the possibility to fabricate high-performance electrode materials for LIBs, especially for amorphous metal oxide-based materials.

A highly resilient mesoporous SiOx lithium storage material engineered by oil-water templating.

PubMed

Park, Eunjun; Park, Min-Sik; Lee, Jaewoo; Kim, Ki Jae; Jeong, Goojin; Kim, Jung Ho; Kim, Young-Jun; Kim, Hansu

2015-02-01

Mesoporous silicon-based materials gained considerable attention as high-capacity lithium-storage materials. However, the practical use is still limited by the complexity and limited number of available synthetic routes. Here, we report carbon-coated porous SiOx as high capacity lithium storage material prepared by using a sol-gel reaction of hydrogen silsesquioxane and oil-water templating. A hydrophobic oil is employed as a pore former inside the SiOx matrix and a precursor for carbon coating on the SiOx . The anode exhibits a high capacity of 730 mAh g(-1) and outstanding cycling performance over 100 cycles without significant dimensional changes. Carbon-coated porous SiOx also showed highly stable thermal reliability comparable to that of graphite. These promising properties come from the mesopores in the SiOx matrix, which ensures reliable operation of lithium storage in SiOx . The scalable sol-gel process presented here can open up a new avenue for the versatile preparation of porous SiOx lithium storage materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Facile Synthesis of Wormhole-Like Mesoporous Tin Oxide via Evaporation-Induced Self-Assembly and the Enhanced Gas-Sensing Properties

NASA Astrophysics Data System (ADS)

Li, Xiaoyu; Peng, Kang; Dou, Yewei; Chen, Jiasheng; Zhang, Yue; An, Gai

2018-01-01

Wormhole-like mesoporous tin oxide was synthesized via a facile evaporation-induced self-assembly (EISA) method, and the gas-sensing properties were evaluated for different target gases. The effect of calcination temperature on gas-sensing properties of mesoporous tin oxide was investigated. The results demonstrate that the mesoporous tin oxide sensor calcined at 400 °C exhibits remarkable selectivity to ethanol vapors comparison with other target gases and has a good performance in the operating temperature and response/recovery time. This might be attributed to their high specific surface area and porous structure, which can provide more active sites and generate more chemisorbed oxygen spices to promote the diffusion and adsorption of gas molecules on the surface of the gas-sensing material. A possible formation mechanism of the mesoporous tin oxide and the enhanced gas-sensing mechanism are proposed. The mesoporous tin oxide shows prospective detecting application in the gas sensor fields.

Controlled Synthesis of Pt Nanowires with Ordered Large Mesopores for Methanol Oxidation Reaction

NASA Astrophysics Data System (ADS)

Zhang, Chengwei; Xu, Lianbin; Yan, Yushan; Chen, Jianfeng

2016-08-01

Catalysts for methanol oxidation reaction (MOR) are at the heart of key green-energy fuel cell technology. Nanostructured Pt materials are the most popular and effective catalysts for MOR. Controlling the morphology and structure of Pt nanomaterials can provide opportunities to greatly increase their activity and stability. Ordered nanoporous Pt nanowires with controlled large mesopores (15, 30 and 45 nm) are facilely fabricated by chemical reduction deposition from dual templates using porous anodic aluminum oxide (AAO) membranes with silica nanospheres self-assembled in the channels. The prepared mesoporous Pt nanowires are highly active and stable electrocatalysts for MOR. The mesoporous Pt nanowires with 15 nm mesopores exhibit a large electrochemically active surface area (ECSA, 40.5 m2 g-1), a high mass activity (398 mA mg-1) and specific activity (0.98 mA cm-2), and a good If/Ib ratio (1.15), better than the other mesoporous Pt nanowires and the commercial Pt black catalyst.

Facile hydrothermal synthesis of mesoporous In2O3 nanoparticles with superior formaldehyde-sensing properties

NASA Astrophysics Data System (ADS)

Zhang, Su; Song, Peng; Yang, Zhongxi; Wang, Qi

2018-03-01

Mesoporous In2O3 nanoparticles were successfully synthesized via a facile, template free, and low-cost hydrothermal method. Their morphology and structure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential thermal and thermogravimetry analysis (DSC-TG), and N2 adsorption-desorption analyses. The results reveal that mesoporous In2O3 nanoparticles with a size range of 40-60 nm, possess plenty of pores, and average pore size is about 5 nm. Importantly, the mesoporous structure, large specific surface area, and small size endow the mesoporous In2O3 nanoparticles with highly sensing performance for formaldehyde detection. The response value to 10 ppm HCHO is 20 at an operating temperature of 280 °C, and the response and recovery time are 4 and 8 s, respectively. It is expected that the mesoporous In2O3 nanoparticles with large specific surface area and excellent sensing properties will become a promising functional material in monitoring and detecting formaldehyde.

Polypyrrole-derived nitrogen and oxygen co-doped mesoporous carbons as efficient metal-free electrocatalyst for hydrazine oxidation.

PubMed

Meng, Yuying; Zou, Xiaoxin; Huang, Xiaoxi; Goswami, Anandarup; Liu, Zhongwu; Asefa, Tewodros

2014-10-08

We demonstrate that polypyrrole-derived nitrogen and oxygen co-doped mesoporous carbons can serve as efficient, metal-free electrocatalysts for hydrazine oxidation reaction, with low overpotential and high current density. The materials' structures and the nature and type of their included dopants, which can be controlled by varying the synthetic conditions, can affect the electrocatalytic properties of the materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

129Xe NMR studies of morphology and accessibility in porous biochar from almond shells

USDA-ARS?s Scientific Manuscript database

Micro and mesoporous materials are often used in catalysis, purification, composite filler, and other applications. Almond shell is an important agricultural byproduct that can be transformed to microporous and mesoporous carbon. In this work, we produced biochar from almond shell using a thermal tr...

One-step synthesis of hydrothermally stable mesoporous aluminosilicates with strong acidity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang Dongjiang; School of Physical and Chemical Sciences, Queensland University of Technology, Brisbane, QLD 4001; Xu Yao

2008-09-15

Using tetraethylorthosilicate (TEOS), polymethylhydrosiloxane (PMHS) and aluminium isopropoxide (AIP) as the reactants, through a one-step nonsurfactant route based on PMHS-TEOS-AIP co-polycondensation, hydrothermally stable mesoporous aluminosilicates with different Si/Al molar ratios were successfully prepared. All samples exclusively showed narrow pore size distribution centered at 3.6 nm. To assess the hydrothermal stability, samples were subjected to 100 deg. C distilled water for 300 h. The boiled mesoporous aluminosilicates have nearly the same N{sub 2} adsorption-desorption isotherms and the same pore size distributions as those newly synthesized ones, indicating excellent hydrothermal stability. The {sup 29}Si MAS NMR spectra confirmed that PMHS and TEOSmore » have jointly condensed and CH{sub 3} groups have been introduced into the materials. The {sup 27}Al MAS NMR spectra indicated that Al atoms have been incorporated in the mesopore frameworks. The NH{sub 3} temperature-programmed desorption showed strong acidity. Due to the existence of large amount of CH{sub 3} groups, the mesoporous aluminosilicates obtained good hydrophobicity. Owing to the relatively large pore and the strong acidity provided by the uniform four-coordinated Al atoms, the excellent catalytic performance for 1,3,5-triisopropylbenzene cracking was acquired easily. The materials may be a profitable complement for the synthesis of solid acid catalysts. - Graphical abstract: Based on the nonsurfactant method, a facile one-step synthesis route has been developed to prepare methyl-modified mesoporous aluminosilicates that possessed hydrothermal stability and strong acidity.« less

Cellulose conjugated FITC-labelled mesoporous silica nanoparticles: intracellular accumulation and stimuli responsive doxorubicin release

NASA Astrophysics Data System (ADS)

Hakeem, Abdul; Zahid, Fouzia; Duan, Ruixue; Asif, Muhammad; Zhang, Tianchi; Zhang, Zhenyu; Cheng, Yong; Lou, Xiaoding; Xia, Fan

2016-02-01

Herein, we design novel cellulose conjugated mesoporous silica nanoparticle (CLS-MSP) based nanotherapeutics for stimuli responsive intracellular doxorubicin (DOX) delivery. DOX molecules are entrapped in pores of the fabricated mesoporous silica nanoparticles (MSPs) while cellulose is used as an encapsulating material through esterification on the outlet of the pores of the MSPs to avoid premature DOX release under physiological conditions. In in vitro studies, stimuli responsive DOX release is successfully achieved from DOX loaded cellulose conjugated mesoporous silica nanoparticles (DOX/CLS-MSPs) by pH and cellulase triggers. Intracellular accumulation of DOX/CLS-MSPs in human liver cancer cells (HepG2 cells) is investigated through confocal microscope magnification. Cell viability of HepG2 cells is determined as the percentage of the cells incubated with DOX/CLS-MSPs compared with that of non-incubated cells through an MTT assay.Herein, we design novel cellulose conjugated mesoporous silica nanoparticle (CLS-MSP) based nanotherapeutics for stimuli responsive intracellular doxorubicin (DOX) delivery. DOX molecules are entrapped in pores of the fabricated mesoporous silica nanoparticles (MSPs) while cellulose is used as an encapsulating material through esterification on the outlet of the pores of the MSPs to avoid premature DOX release under physiological conditions. In in vitro studies, stimuli responsive DOX release is successfully achieved from DOX loaded cellulose conjugated mesoporous silica nanoparticles (DOX/CLS-MSPs) by pH and cellulase triggers. Intracellular accumulation of DOX/CLS-MSPs in human liver cancer cells (HepG2 cells) is investigated through confocal microscope magnification. Cell viability of HepG2 cells is determined as the percentage of the cells incubated with DOX/CLS-MSPs compared with that of non-incubated cells through an MTT assay. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08753h

Modified SBA-15 as the carrier for metoprolol and papaverine: Adsorption and release study

NASA Astrophysics Data System (ADS)

Moritz, MichaŁ; łaniecki, Marek

2011-07-01

A series of modified SBA-15 materials were applied in drug delivery systems. The internal surface of siliceous hexagonal structure of SBA-15 was modified with different amount of (3-mercaptopropyl)trimethoxysilane (MPTMS) and oxidized in the presence of hydrogen peroxide. The sulfonated material was loaded with metoprolol tartrate or papaverine hydrochloride. Both drugs indicated strong chemical interaction with modified mesoporous surface. The characteristic of the obtained materials was performed with XRD and DRUV-vis spectrometry, themogravimetry and nitrogen adsorption (BET) measurements. The obtained results show that modification of the mesoporous materials leads towards significant decrease of the drug delivery rate.

Synthesis of hierarchical mesoporous lithium nickel cobalt manganese oxide spheres with high rate capability for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Tong, Wei; Huang, Yudai; Cai, Yanjun; Guo, Yong; Wang, Xingchao; Jia, Dianzeng; Sun, Zhipeng; Pang, Weikong; Guo, Zaiping; Zong, Jun

2018-01-01

Hierarchical mesoporous LiNi1/3Co1/3Mn1/3O2 spheres have been synthesized by urea-assisted solvothermal method with adding Triton X-100. The structure and morphology of the as-prepared materials were analyzed by X-ray diffraction and electron microscope. The results show that the as-prepared samples can be indexed as hexagonal layered structure with hierarchical architecture, and the possible formation mechanism is speculated. When evaluated as cathode material, the hierarchical mesoporous LiNi1/3Co1/3Mn1/3O2 spheres show good electrochemical properties with high initial discharge capacity of 129.9 mAh g-1, and remain the discharge capacity of 95.5 mAh g-1 after 160 cycles at 10C. The excellent electrochemical performance of the as-prepared sample can be attributed to its stable hierarchical mesoporous framework in conjunction with large specific surface, low cation mixing and small particle size. They not only provide a large number of reaction sites for surface or interface reaction, but also shorten the diffusion length of Li+ ions. Meanwhile, the mesoporous spheres composed of nanoparticles can contribute to high rate ability and buffer volume changes during charge/discharge process.

Direct synthesis and application of bridged diamino-functionalized periodic mesoporous organosilicas with high nitrogen contents

NASA Astrophysics Data System (ADS)

Zhu, Feng-Xia; Zhao, Pu-Su; Sun, Xiao-Jun; An, Li-Tao; Deng, Yong; Wu, Jia-Min

2017-11-01

Bridged diamino-functionalized periodic mesoporous organosilicas [BD-PMO(Et), Et = ethyl] materials were synthesized directly by co-condensation of 2-bis (triethoxysilyl)ethane (BTEE) and 1,4-bis[3-(tirmethoxysilyl)-propyl]ethylenediamino (BTMSEN) under acidic conditions with pluronic triblock copolymer P123 as a template. The nitrogen content in BD-PMO(Et) could be adjusted up to 40% without disturbing the ordered mesoporous structure. These materials were proved to be effective heterogeneous catalysts for the liquid-phase reactions such as Knoevenagel and Henry condensations as well as in the intermolecular cross-double-Michael addition reaction between α-methyl-β-nitrostyrene and α, β-unsaturated ketone. They exhibited comparable catalytic activities with homogeneous catalyst piperazine and can be reused for several times without any negative environmental impact.

Formation pathways of mesoporous silica nanoparticles with dodecagonal tiling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Yao; Ma, Kai; Kao, Teresa

Considerable progress in the fabrication of quasicrystals demonstrates that they can be realized in a broad range of materials. However, the development of chemistries enabling direct experimental observation of early quasicrystal growth pathways remains challenging. Here, we report the synthesis of four surfactant-directed mesoporous silica nanoparticle structures, including dodecagonal quasicrystalline nanoparticles, as a function of micelle pore expander concentration or stirring rate. We demonstrate that the early formation stages of dodecagonal quasicrystalline mesoporous silica nanoparticles can be preserved, where precise control of mesoporous silica nanoparticle size down to <30 nm facilitates comparison between mesoporous silica nanoparticles and simulated single-particle growthmore » trajectories beginning with a single tiling unit. Our results reveal details of the building block size distributions during early growth and how they promote quasicrystal formation. This work identifies simple synthetic parameters, such as stirring rate, that may be exploited to design other quasicrystal-forming self-assembly chemistries and processes.« less

Mesoporous gold sponges: electric charge-assisted seed mediated synthesis and application as surface-enhanced Raman scattering substrates

NASA Astrophysics Data System (ADS)

Yi, Zao; Luo, Jiangshan; Tan, Xiulan; Yi, Yong; Yao, Weitang; Kang, Xiaoli; Ye, Xin; Zhu, Wenkun; Duan, Tao; Yi, Yougen; Tang, Yongjian

2015-11-01

Mesoporous gold sponges were prepared using 4-dimethylaminopyridine (DMAP)-stabilized Au seeds. This is a general process, which involves a simple template-free method, room temperature reduction of HAuCl4·4H2O with hydroxylamine. The formation process of mesoporous gold sponges could be accounted for the electrostatic interaction (the small Au nanoparticles (~3 nm) and the positively charged DMAP-stabilized Au seeds) and Ostwald ripening process. The mesoporous gold sponges had appeared to undergo electrostatic adsorption initially, sequentially linear aggregation, welding and Ostwald ripening, then, they randomly cross link into self-supporting, three-dimensional networks with time. The mesoporous gold sponges exhibit higher surface area than the literature. In addition, application of the spongelike networks as an active material for surface-enhanced Raman scattering has been investigated by employing 4-aminothiophenol (4-ATP) molecules as a probe.

Formation pathways of mesoporous silica nanoparticles with dodecagonal tiling

DOE PAGES

Sun, Yao; Ma, Kai; Kao, Teresa; ...

2017-08-15

Considerable progress in the fabrication of quasicrystals demonstrates that they can be realized in a broad range of materials. However, the development of chemistries enabling direct experimental observation of early quasicrystal growth pathways remains challenging. Here, we report the synthesis of four surfactant-directed mesoporous silica nanoparticle structures, including dodecagonal quasicrystalline nanoparticles, as a function of micelle pore expander concentration or stirring rate. We demonstrate that the early formation stages of dodecagonal quasicrystalline mesoporous silica nanoparticles can be preserved, where precise control of mesoporous silica nanoparticle size down to <30 nm facilitates comparison between mesoporous silica nanoparticles and simulated single-particle growthmore » trajectories beginning with a single tiling unit. Our results reveal details of the building block size distributions during early growth and how they promote quasicrystal formation. This work identifies simple synthetic parameters, such as stirring rate, that may be exploited to design other quasicrystal-forming self-assembly chemistries and processes.« less

Template-free synthesis of mesoporous nanoring-like Zn-Co mixed oxides with high lithium storage performance

NASA Astrophysics Data System (ADS)

Lu, Lun; Gao, Yan-Li; Yang, Zhi-Zheng; Wang, Cheng; Wang, Jin-Guo; Wang, Hui-Yuan; Jiang, Qi-Chuan

2018-04-01

Mesoporous nanoring-like Zn-Co mixed oxides are synthesized via a simple template-free solvothermal method with a subsequent annealing process. The ring-like nanostructures with hollow interiors are formed under the complexing effects of potassium sodium tartrate. Numerous mesopores are generated after the precursor is annealed at 500 °C. When applied as anode materials, the mesoporous nanoring-like Zn-Co mixed oxides can deliver a high discharge capacity of 1102 mAh g-1 after 200 cycles at 500 mA g-1. Even when the current density is increased to 2 A g-1, the mixed oxides can still retain a reversible capacity of 761 mAh g-1. Such high cycling stability and rate capability are mainly derived from the unique mesoporous ring-like nanostructures and the synergistic effects between Zn and Co based oxides.

Synthesis and characterization of nanoparticulate MnS within the pores of mesoporous silica

NASA Astrophysics Data System (ADS)

Barry, Louse; Copley, Mark; Holmes, Justin D.; Otway, David J.; Kazakova, Olga; Morris, Michael A.

2007-12-01

Mesoporous silica was loaded with nanoparticulate MnS via a simple post-synthesis treatment. The mesoporous material that still contained surfactant was passivated to prevent MnS formation at the surface. The surfactant was extracted and a novel manganese ethylxanthate was used to impregnate the pore network. This precursor thermally decomposes to yield MnS particles that are smaller or equal to the pore size. The particles exhibit all three common polymorphs. The passivation treatment is most effective at lower loadings because at the highest loadings (SiO 2:MnS molar ratio of 6:1) large particles (>50 nm) form at the exterior of the mesoporous particles. The integrity of the mesoporous network is maintained through the preparation and high order is maintained. The MnS particles exhibit unexpected ferromagnetism at low temperatures. Strong luminescence of these samples is observed and this suggests that they may have a range of important application areas.

Mesoporous gold sponges: electric charge-assisted seed mediated synthesis and application as surface-enhanced Raman scattering substrates

PubMed Central

Yi, Zao; Luo, Jiangshan; Tan, Xiulan; Yi, Yong; Yao, Weitang; Kang, Xiaoli; Ye, Xin; Zhu, Wenkun; Duan, Tao; Yi, Yougen; Tang, Yongjian

2015-01-01

Mesoporous gold sponges were prepared using 4-dimethylaminopyridine (DMAP)-stabilized Au seeds. This is a general process, which involves a simple template-free method, room temperature reduction of HAuCl4·4H2O with hydroxylamine. The formation process of mesoporous gold sponges could be accounted for the electrostatic interaction (the small Au nanoparticles (~3 nm) and the positively charged DMAP-stabilized Au seeds) and Ostwald ripening process. The mesoporous gold sponges had appeared to undergo electrostatic adsorption initially, sequentially linear aggregation, welding and Ostwald ripening, then, they randomly cross link into self-supporting, three-dimensional networks with time. The mesoporous gold sponges exhibit higher surface area than the literature. In addition, application of the spongelike networks as an active material for surface-enhanced Raman scattering has been investigated by employing 4-aminothiophenol (4-ATP) molecules as a probe. PMID:26538365

Nitrogen-enriched carbon with extremely high mesoporosity and tunable mesopore size for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Yang, Xiaoqing; Li, Chengfei; Fu, Ruowen

2016-07-01

As one of the most potential electrode materials for supercapacitors, nitrogen-enriched nanocarbons are still facing challenge of constructing developed mesoporosity for rapid mass transportation and tailoring their pore size for performance optimization and expanding their application scopes. Herein we develop a series of nitrogen-enriched mesoporous carbon (NMC) with extremely high mesoporosity and tunable mesopore size by a two-step method using silica gel as template. In our approach, mesopore size can be easily tailored from 4.7 to 35 nm by increasing the HF/TEOS volume ratio from 1/100 to 1/4. The NMC with mesopores of 6.2 nm presents the largest mesopore volume, surface area and mesopore ratio of 2.56 cm3 g-1, 1003 m2 g-1 and 97.7%, respectively. As a result, the highest specific capacitance of 325 F g-1 can be obtained at the current density of 0.1 A g-1, which can stay over 88% (286 F g-1) as the current density increases by 100 times (10 A g-1). This approach may open the doors for preparation of nitrogen-enriched nanocarbons with desired nanostructure for numerous applications.

In vitro and in vivo evaluation of ordered mesoporous silica as a novel adsorbent in liquisolid formulation

PubMed Central

Chen, Bao; Wang, Zhouhua; Quan, Guilan; Peng, Xinsheng; Pan, Xin; Wang, Rongchang; Xu, Yuehong; Li, Ge; Wu, Chuanbin

2012-01-01

Background A liquisolid technique has been reported to be a new approach to improve the release of poorly water-soluble drugs for oral administration. However, an apparent limitation of this technique is the formulation of a high dose because a large amount of liquid vehicle is needed, which finally results in a low-dose liquisolid formulation. Silica as an absorbent has been used extensively in liquisolid formulations. Although nanoparticle silica can be prepared and used to improve liquid adsorption capacity, loading a high dose of drug into a liquisolid is still a challenge. With the aim of improving adsorption capacity and accordingly achieving high drug loading, ordered mesoporous silica with a high surface area and narrow pore size distribution was synthesized and used in a liquisolid formulation. Methods Ordered mesoporous silica was synthesized and its particle size and morphology were tailored by controlling the concentration of cetyltrimethyl ammonium bromide. The ordered mesoporous silica synthesized was characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, small-angle x-ray diffraction, wide angle x-ray diffraction, and nitrogen adsorption-desorption measurements. The liquid adsorption capacity of ordered mesoporous silica was subsequently compared with that of conventional silica materials using PEG400 as the model liquid. Carbamazepine was chosen as a model drug to prepare the liquisolid formulation, with ordered mesoporous silica as the adsorbent material. The preparation was evaluated and compared with commercially available fast-release carbamazepine tablets in vitro and in vivo. Results Characterization of the ordered mesoporous silica synthesized in this study indicated a huge Brunauer–Emmett–Teller surface area (1030 m2/g), an ordered mesoporous structure with a pore size of 2.8 nm, and high adsorption capacity for liquid compared with conventional silica. Compared with fast-release commercial carbamazepine tablets, drug release from the liquisolid capsules was greatly improved, and the bioavailability of the liquisolid preparation was enhanced by 182.7%. Conclusion Ordered mesoporous silica is a potentially attractive adsorbent which may lead to a new approach for development of liquisolid products. PMID:22275835

Sol Gel-Derived SBA-16 Mesoporous Material

PubMed Central

Rivera-Muñoz, Eric M.; Huirache-Acuña, Rafael

2010-01-01

The aim of this article is to review current knowledge related to the synthesis and characterization of sol gel-derived SBA-16 mesoporous silicas, as well as a review of the state of the art in this issue, to take stock of knowledge about current and future applications. The ease of the method of preparation, the orderly structure, size and shape of their pores and control, all these achievable through simple changes in the method of synthesis, makes SBA-16 a very versatile material, potentially applicable in many areas of science and molecular engineering of materials. PMID:20957080

TiO2-coated mesoporous carbon: conventional vs. microwave-annealing process.

PubMed

Coromelci-Pastravanu, Cristina; Ignat, Maria; Popovici, Evelini; Harabagiu, Valeria

2014-08-15

The study of coating mesoporous carbon materials with titanium oxide nanoparticles is now becoming a promising and challenging area of research. To optimize the use of carbon materials in various applications, it is necessary to attach functional groups or other nanostructures to their surface. The combination of the distinctive properties of mesoporous carbon materials and titanium oxide is expected to be applied in field emission displays, nanoelectronic devices, novel catalysts, and polymer or ceramic reinforcement. But, their synthesis is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors, which takes time and money. The thermal heating based techniques are time consuming and often lack control of particle size and morphology. Hence, since there is a growing interest in microwave technology, an alternative way of power input into chemical reactions through dielectric heating is the use of microwaves. This work is focused on the advantages of microwave-assisted synthesis of TiO2-coated mesoporous carbon over conventional thermal heating method. The reviewed studies showed that the microwave-assisted synthesis of such composites allows processes to be completed within a shorter reaction time allowing the nanoparticles formation with superior properties than that obtained by conventional method. Copyright © 2014 Elsevier B.V. All rights reserved.

Silica-based mesoporous nanoparticles for controlled drug delivery

PubMed Central

Kwon, Sooyeon; Singh, Rajendra K; Perez, Roman A; Abou Neel, Ensanya A

2013-01-01

Drug molecules with lack of specificity and solubility lead patients to take high doses of the drug to achieve sufficient therapeutic effects. This is a leading cause of adverse drug reactions, particularly for drugs with narrow therapeutic window or cytotoxic chemotherapeutics. To address these problems, there are various functional biocompatible drug carriers available in the market, which can deliver therapeutic agents to the target site in a controlled manner. Among the carriers developed thus far, mesoporous materials emerged as a promising candidate that can deliver a variety of drug molecules in a controllable and sustainable manner. In particular, mesoporous silica nanoparticles are widely used as a delivery reagent because silica possesses favourable chemical properties, thermal stability and biocompatibility. Currently, sol-gel-derived mesoporous silica nanoparticles in soft conditions are of main interest due to simplicity in production and modification and the capacity to maintain function of bioactive agents. The unique mesoporous structure of silica facilitates effective loading of drugs and their subsequent controlled release. The properties of mesopores, including pore size and porosity as well as the surface properties, can be altered depending on additives used to fabricate mesoporous silica nanoparticles. Active surface enables functionalisation to modify surface properties and link therapeutic molecules. The tuneable mesopore structure and modifiable surface of mesoporous silica nanoparticle allow incorporation of various classes of drug molecules and controlled delivery to the target sites. This review aims to present the state of knowledge of currently available drug delivery system and identify properties of an ideal drug carrier for specific application, focusing on mesoporous silica nanoparticles. PMID:24020012

Highly ordered mesoporous cobalt oxide nanostructures: synthesis, characterisation, magnetic properties, and applications for electrochemical energy devices.

PubMed

Wang, Guoxiu; Liu, Hao; Horvat, Josip; Wang, Bei; Qiao, Shizhang; Park, Jinsoo; Ahn, Hyojun

2010-09-24

Highly ordered mesoporous Co(3)O(4) nanostructures were prepared using KIT-6 and SBA-15 silica as hard templates. The structures were confirmed by small angle X-ray diffraction, high resolution transmission electron microscopy, and N(2) adsorption-desorption isotherm analysis. Both KIT-6 cubic and SBA-15 hexagonal mesoporous Co(3)O(4) samples exhibited a low Néel temperature and bulk antiferromagnetic coupling due to geometric confinement of antiferromagnetic order within the nanoparticles. Mesoporous Co(3)O(4) electrode materials have demonstrated the high lithium storage capacity of more than 1200 mAh g(-1) with an excellent cycle life. They also exhibited a high specific capacitance of 370 F g(-1) as electrodes in supercapacitors.

Sol–gel synthesis of MCM-41 silicas and selective vapor-phase modification of their surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roik, N.V., E-mail: roik_nadya@ukr.net; Belyakova, L.A.

2013-11-15

Silica particles with uniform hexagonal mesopore architecture were synthesized by template directed sol–gel condensation of tetraethoxysilane or mixture of tetraethoxysilane and (3-chloropropyl)triethoxysilane in a water–ethanol–ammonia solution. Selective functionalization of exterior surface of parent materials was carried out by postsynthetic treatment of template-filled MCM-41 and Cl-MCM-41 with vapors of (3-chloropropyl)triethoxysilane and 1,2-ethylenediamine in vacuum. The chemical composition of obtained mesoporous silicas was estimated by IR spectroscopy and chemical analysis of surface products of reactions. Characteristics of porous structure of resulting materials were determined from the data of X-ray, low-temperature nitrogen ad-desorption and transmission electron microscopy measurements. Obtained results confirm invariability ofmore » highly ordered mesoporous structure of MCM-41 and Cl-MCM-41 after their selective postsynthetic modification in vapor phase. It was proved that proposed method of vapor-phase functionalization of template-filled starting materials is not accompanied by dissolution of the template and chemical modification of pores surface. This provides preferential localization of grafted functional groups onto the exterior surface of mesoporous silicas. - Graphical abstract: Sol–gel synthesis and postsynthetic chemical modification of template-filled MCM-41 and Cl-MCM-41 with (3-chloropropyl)triethoxysilane and 1,2-ethylenediamine in vapor phase. Display Omitted - Highlights: • Synthesis of MCM-41 silica by template directed sol–gel condensation. • Selective vapor-phase functionalization of template-filled silica particles. • Preferential localization of grafted groups onto the exterior surface of mesoporous silicas.« less

Tuneable porous carbonaceous materials from renewable resources.

PubMed

White, Robin J; Budarin, Vitaly; Luque, Rafael; Clark, James H; Macquarrie, Duncan J

2009-12-01

Porous carbon materials are ubiquitous with a wide range of technologically important applications, including separation science, heterogeneous catalyst supports, water purification filters, stationary phase materials, as well as the developing future areas of energy generation and storage applications. Hard template routes to ordered mesoporous carbons are well established, but whilst offering different mesoscopic textural phases, the surface of the material is difficult to chemically post-modify and processing is energy, resource and step intensive. The production of carbon materials from biomass (i.e. sugars or polysaccharides) is a relatively new but rapidly expanding research area. In this tutorial review, we compare and contrast recently reported routes to the preparation of porous carbon materials derived from renewable resources, with examples of our previously reported mesoporous polysaccharide-derived "Starbon" carbonaceous material technology.

Fluorination of “brick and mortar” soft-templated graphitic ordered mesoporous carbons for high power lithium-ion battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fulvio, Pasquale F.; Veith, Gabriel M.; Adcock, Jamie L.

2013-03-18

We prepared ordered mesoporous carbon graphitic carbon composites by the brick and mortar fluorinated methodusing F 2 and investigated as cathodes for primary lithium batteries. Our resulting materials have a rich array of C F species, asmeasured by XPS, which influence conduction and voltage profiles.

Quasi 2D Mesoporous Carbon Microbelts Derived from Fullerene Crystals as an Electrode Material for Electrochemical Supercapacitors.

PubMed

Tang, Qin; Bairi, Partha; Shrestha, Rekha Goswami; Hill, Jonathan P; Ariga, Katsuhiko; Zeng, Haibo; Ji, Qingmin; Shrestha, Lok Kumar

2017-12-27

Fullerene C 60 microbelts were fabricated using the liquid-liquid interfacial precipitation method and converted into quasi 2D mesoporous carbon microbelts by heat treatment at elevated temperatures of 900 and 2000 °C. The carbon microbelts obtained by heat treatment of fullerene C 60 microbelts at 900 °C showed excellent electrochemical supercapacitive performance, exhibiting high specific capacitances ca. 360 F g -1 (at 5 mV s -1 ) and 290 F g -1 (at 1 A g -1 ) because of the enhanced surface area and the robust mesoporous framework structure. Additionally, the heat-treated carbon microbelt showed good rate performance, retaining 49% of capacitance at a high scan rate of 10 A g -1 . The carbon belts exhibit super cyclic stability. Capacity loss was not observed even after 10 000 charge/discharge cycles. These results demonstrate that the quasi 2D mesoporous carbon microbelts derived from a π-electron-rich carbon source, fullerene C 60 crystals, could be used as a new candidate material for electrochemical supercapacitor applications.

Nitrogen enriched mesoporous organic polymer anchored copper(II) material: an efficient and reusable catalyst for the synthesis of esters and amides from aromatic systems.

PubMed

Molla, Rostam Ali; Iqubal, Md Asif; Ghosh, Kajari; Kamaluddin; Islam, Sk Manirul

2015-04-14

A new copper-grafted mesoporous poly-melamine-formaldehyde (Cu-mPMF) has been synthesized from melamine and paraformaldehyde in DMSO medium, followed by grafting of Cu(ii) at its surface. Cu-mPMF has been characterized by elemental analysis, powder XRD, HR TEM, FE-SEM, N2 adsorption study, FT-IR, UV-vis DRS, TGA-DTA, EPR spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The Cu-grafted mesoporous material showed very good catalytic activity in methyl esterification of benzylic alcohols and amidation of nitriles. Moreover, the catalyst is easily recoverable and can be reused seven times without appreciable loss of catalytic activity in the above reactions. The highly dispersed and strongly bound Cu(ii) sites in the Cu-grafted mesoporous polymer could be responsible for the observed high activities of the Cu-mPMF catalyst. Due to strong binding with the functional groups of the polymer, no evidence of leached copper from the catalyst during the course of reaction emerged, suggesting true heterogeneity in the catalytic process.

Multifunctional materials such as MCM-41÷Fe3O4÷folic acid as drug delivery system.

PubMed

Popescu, Simona; Ardelean, Ioana Lavinia; Gudovan, Dragoş; Rădulescu, Marius; Ficai, Denisa; Ficai, Anton; Vasile, Bogdan Ştefan; Andronescu, Ecaterina

2016-01-01

In this study, MCM-41 mesoporous silica nanoparticles (NPs) and MCM-41÷Fe3O4 mesoporous silica NPs were prepared by sol-gel method using CTAB (cetyltrimethylammonium bromide) as template and TEOS (tetraethyl orthosilicate) as silica precursor in order to use these materials as drug delivery system (DDS) for different biologically active agents. The MCM-41 and MCM-41÷Fe3O4 mesoporous silica NPs were characterized using specific physico-chemical methods [transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption and desorption studies - BET (Brunauer-Emmett-Teller) method, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy], while the release studies were done by a high-performance liquid chromatography (HPLC)-modified method. The pH dependence of the delivery of folic acid from the mesoporous structures was analyzed and found that the release is pH sensitive. The lower delivery at strongly acid pH comparing with neutral/slightly alkaline pH could be beneficial because in stomach the folic acid can be destroyed.

Mesoporous wormholelike carbon with controllable nanostructure for lithium ion batteries application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xiaoqing, E-mail: yxq-886@163.com; Li, Xinxi; Li, Zhenghui

2015-06-15

Highlights: • Wormholelike carbon (WMC) with controllable nanostructure is prepared by sol–gel method. • The reversible capacity of WMC is much higher than that of many other reported nanocarbons. • The effect of pore diameter on Li storage capacity is investigated. - Abstract: A class of mesoporous wormholelike carbon (WMC) with controllable nanostructure was prepared by sol–gel method and then used as the anode material of lithium-ion batteries. Based on the experimental results, it is found that the nanostructure of the as-prepared WMC plays an important role in the electrochemical performances. A suitable mesopore size is necessary for a highmore » performance carbon-based anode material since it can not only guarantee effective mass transport channels but also provide large surface area. As a result, F30 with a mesopore size of 4.4 nm coupled with high surface area of 1077 m{sup 2} g{sup −1} shows a reversible capacity of 630 mAh g{sup −1}, much higher than commercial graphite and many other reported nanocarbons.« less

Mesoporous materials and nanocrystals for enhancing the dissolution behavior of poorly water-soluble drugs.

PubMed

Santos, Helder A; Peltonen, Leena; Limnell, Tarja; Hirvonen, Jouni

2013-01-01

Advanced drug delivery formulations are presently recognized as promising tools for overcoming the adverse physicochemical properties of conventional drug molecules, such as poor water solubility, which often leads to poor drug bioavailability. Oral drug delivery is considered as the easiest and most convenient route of drug administration. However, via the current trends utilizing combinatorial chemistry and high throughput screening in drug development, new drug molecules are moving towards lipophilic and poorly water-soluble large molecules, and the oral delivery route is becoming increasingly challenging. In this context, formulation of poorly soluble and/or permeable drugs using mesoporous materials and nanocrystals technology have proven to be highly successful due to the greater surface/volume ratio of these systems, resulting in improvements in dissolution and bioavailability, as well as enhanced drug permeability. This review addresses the issues of poorly water-soluble drugs with a major focus on recent developments in the application of the mesoporous materials (e.g., porous silicon and silica) and nanocrystals in drug delivery applications. In addition, we present several recent examples of the significant potential of these materials for the pharmaceutical field.

Activated microporous-mesoporous carbon derived from chestnut shell as a sustainable anode material for high performance microbial fuel cells.

PubMed

Chen, Qin; Pu, Wenhong; Hou, Huijie; Hu, Jingping; Liu, Bingchuan; Li, Jianfeng; Cheng, Kai; Huang, Long; Yuan, Xiqing; Yang, Changzhu; Yang, Jiakuan

2018-02-01

Microbial fuel cells (MFCs) are promising biotechnologies tool to harvest electricity by decomposing organic matter in waste water, and the anode material is a critical factor in determining the performance of MFCs. In this study, chestnut shell is proposed as a novel anode material with mesoporous and microporous structure prepared via a simple carbonization procedure followed by an activation process. The chemical activation process successfully modified the macroporous structure, created more mesoporous and microporous structure and decreased the O-content and pyridinic/pyrrolic N groups on the biomass anode, which were beneficial for improving charge transfer efficiency between the anode surface and microbial biofilm. The MFC with activated biomass anode achieved a maximum power density (23.6 W m -3 ) 2.3 times higher than carbon cloth anode (10.4 W m -3 ). This study introduces a promising and feasible strategy for the fabrication of high performance anodes for MFCs derived from cost-effective, sustainable natural materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multifunctional mesoporous silica nanoparticles for combined therapeutic, diagnostic and targeted action in cancer treatment.

PubMed

Rosenholm, Jessica M; Sahlgren, Cecilia; Lindén, Mika

2011-07-01

The main objective in the development of nanomedicine is to obtain delivery platforms for targeted delivery of drugs or imaging agents for improved therapeutic efficacy, reduced side effects and increased diagnostic sensitivity. A (nano)material class that has been recognized for its controllable properties on many levels is ordered mesoporous inorganic materials, typically in the form of amorphous silica (SiO2). Characteristics for this class of materials include mesoscopic order, tunable pore dimensions in the (macro)molecular size range, a high pore volume and surface area, the possibility for selective surface functionality as well as morphology control. The robust but biodegradable ceramic matrix moreover provides shelter for incorporated agents (drugs, proteins, imaging agents, photosensitizers) leaving the outer particle surface free for further modification. The unique features make these materials particularly amenable to modular design, whereby functional moieties and features may be interchanged or combined to produce multifunctional nanodelivery systems combining targeting, diagnostic, and therapeutic actions. This review covers the latest developments related to the use of mesoporous silica nanoparticles (MSNs) as nanocarriers in biomedical applications, with special focus on cancer therapy and diagnostics.

Mesoporous silicon oxide films and their uses as templates in obtaining nanostructured conductive polymers

NASA Astrophysics Data System (ADS)

Salgado, R.; Arteaga, G. C.; Arias, J. M.

2018-04-01

Obtaining conductive polymers (CPs) for the manufacture of OLEDs, solar cells, electrochromic devices, sensors, etc., has been possible through the use of electrochemical techniques that allow obtaining films of controlled thickness with positive results in different applications. Current trends point towards the manufacture of nanomaterials, and therefore it is necessary to develop methods that allow obtaining CPs with nanostructured morphology. This is possible by using a porous template to allow the growth of the polymeric materials. However, prior and subsequent treatments are required to separate the material from the template so that it can be evaluated in the applications mentioned above. This is why mesoporous silicon oxide films (template) are essential for the synthesis of nanostructured polymers since both the template and the polymer are obtained on the electrode surface, and therefore it is not necessary to separate the material from the template. Thus, the material can be evaluated directly in the applications mentioned above. The dimensions of the resulting nanostructures will depend on the power, time and technique used for electropolymerization as well as the monomer and the surfactant of the mesoporous film.

Sulfur-infiltrated porous carbon microspheres with controllable multi-modal pore size distribution for high energy lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Zhao, Cunyu; Liu, Lianjun; Zhao, Huilei; Krall, Andy; Wen, Zhenhai; Chen, Junhong; Hurley, Patrick; Jiang, Junwei; Li, Ying

2013-12-01

Sulfur has received increasing attention as a cathode material for lithium-sulfur (Li-S) batteries due to its high theoretical specific capacity. However, the commercialization of Li-S batteries is limited by the challenges of poor electrical conductivity of sulfur, dissolution of the polysulfide intermediates into the electrolyte, and volume expansion of sulfur during cycling. Herein, we report the fabrication of novel-structured porous carbon microspheres with a controllable multi-modal pore size distribution, i.e., a combination of interconnected micropores, mesopores and macropores. Cathodes made of sulfur infiltrated in such a hierarchical carbon framework provide several advantages: (1) a continuous and high surface area carbon network for enhanced electrical conductivity and high sulfur loading; (2) macropores and large mesopores bridged by small mesopores to provide good electrolyte accessibility and fast Li ion transport and to accommodate volume expansion of sulfur; and (3) small mesopores and micropores to improve carbon/sulfur interaction and to help trap polysulfides. An initial discharge capacity at 1278 mA h g-1 and capacity retention at 70.7% (904 mA h g-1) after 100 cycles at a high rate (1 C) were achieved. The material fabrication process is relatively simple and easily scalable.Sulfur has received increasing attention as a cathode material for lithium-sulfur (Li-S) batteries due to its high theoretical specific capacity. However, the commercialization of Li-S batteries is limited by the challenges of poor electrical conductivity of sulfur, dissolution of the polysulfide intermediates into the electrolyte, and volume expansion of sulfur during cycling. Herein, we report the fabrication of novel-structured porous carbon microspheres with a controllable multi-modal pore size distribution, i.e., a combination of interconnected micropores, mesopores and macropores. Cathodes made of sulfur infiltrated in such a hierarchical carbon framework provide several advantages: (1) a continuous and high surface area carbon network for enhanced electrical conductivity and high sulfur loading; (2) macropores and large mesopores bridged by small mesopores to provide good electrolyte accessibility and fast Li ion transport and to accommodate volume expansion of sulfur; and (3) small mesopores and micropores to improve carbon/sulfur interaction and to help trap polysulfides. An initial discharge capacity at 1278 mA h g-1 and capacity retention at 70.7% (904 mA h g-1) after 100 cycles at a high rate (1 C) were achieved. The material fabrication process is relatively simple and easily scalable. Electronic supplementary information (ESI) available: Preparation process scheme; X-ray mapping images and EDX analysis for the surface of PMC/S-40; X-ray mapping images for the cross-section of PMC/S-40; thermogravimetric analysis (TGA) of PMC/S samples; T-plot results for PMC sample; and electrochemical measurements of lithium-sulfur batteries using PMC/S as cathode materials. See DOI: 10.1039/c3nr04532c

Structural and magnetic properties of the nanocomposite materials based on a mesoporous silicon dioxide matrix

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grigor’eva, N. A., E-mail: natali@lns.pnpi.spb.ru; Eckerlebe, H.; Eliseev, A. A.

2017-03-15

The structural and magnetic properties of the mesoporous systems based on silicon dioxide with a regular hexagonal arrangement of pores several microns in length and several nanometers in diameter, which are filled with iron compound nanofilaments in various chemical states, are studied in detail. The studies are performed using the following mutually complementary methods: transmission electron microscopy, SQUID magnetometry, electron spin resonance, Mössbauer spectroscopy, polarized neutron small-angle diffraction, and synchrotron radiation diffraction. It is shown that the iron nanoparticles in pores are mainly in the γ phase of Fe{sub 2}O{sub 3} with a small addition of the α phase andmore » atomic iron clusters. The effective magnetic field acting on a nanofilament from other nanofilaments is 11 mT and has a dipole nature, the ferromagnetic–paramagnetic transition temperature is in the range 76–94 K depending on the annealing temperature of the samples, and the temperature that corresponds to the change in the magnetic state of the iron oxide nanofilaments is T ≈ 50–60 K at H = 0 and T ≈ 80 K at H = 300 mT. It is also shown that the magnetization reversal of an array of nanofilaments is caused by the magnetostatic interaction between nanofilaments at the fields that are lower than the saturation field.« less

Catalytic properties of mesoporous Al–La–Mn oxides prepared via spray pyrolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Goun; Jung, Kyeong Youl; Lee, Choul-Ho

Highlights: • Al–La–Mn oxides were prepared using spray pyrolysis. • Al–La–Mn oxides exhibit large and uniform pore sizes. • Mesoporous Al–La–Mn oxides were compared with those prepared by conventional precipitation. • Mesoporous Al–La–Mn oxides show superior activity in decomposition of hydrogen peroxide. - Abstract: Mesoporous Al–La–Mn oxides are prepared via spray pyrolysis and are applied to the catalytic decomposition of hydrogen peroxide. The characteristics of the mesoporous Al–La–Mn oxides are examined using N{sub 2} adsorption, X-ray diffraction, and X-ray fluorescence measurements. The surface area and pore size of the Al–La–Mn oxides prepared via spray pyrolysis are larger than those ofmore » the Al–La–Mn oxides prepared using a precipitation method. The catalytic performance of the materials during the decomposition of hydrogen peroxide is examined in a pulse-injection reactor. It is confirmed that the mesoporous Al–La–Mn oxides prepared via spray pyrolysis exhibit higher catalytic activity and stability in the decomposition of hydrogen peroxide than Al–La–Mn oxides prepared using a conventional precipitation method.« less

Isolated Mesoporous Microstructures Prepared by Stress Localization-Induced Crack Manipulation.

PubMed

Wooh, Sanghyuk; Lee, Soojin; Lee, Yunchan; Ryu, Ji Ho; Lee, Won Bo; Yoon, Hyunsik; Char, Kookheon

2016-09-22

Cracks observed in brittle materials are mostly regarded as defects or failures. However, they can be a valuable tool when implemented in a controlled way. Here, we introduce a strategy to control the crack propagation of mesoporous micropatterns (prisms and pyramids), which leads to the isolation of well-defined microstructures. Mesoporous micropatterns were fabricated by the soft imprinting technique with wet TiO 2 nanoparticle (NP) pastes, followed by sintering to remove organic components. Since the volume of the paste significantly shrinks during the sintering step, stress is localized at the edge of micropatterns, in good agreement with finite element method simulations, creating well-defined cracks and their propagation. It was demonstrated that the degree of stress localization is determined by the thickness of residual layers, NP size, and heating rate. After controlled crack propagation and delamination of microparticles from the substrates, mesoporous microwires and microparticles were successfully produced and functionalized from the isolated mesoporous prisms and pyramids. The method proposed in this study for controlled crack manipulation and delamination opens a door for straightforward and economical fabrication of well-defined mesoporous microparticles.

Mesopores induced zero thermal expansion in single-crystal ferroelectrics.

PubMed

Ren, Zhaohui; Zhao, Ruoyu; Chen, Xing; Li, Ming; Li, Xiang; Tian, He; Zhang, Ze; Han, Gaorong

2018-04-24

For many decades, zero thermal expansion materials have been the focus of numerous investigations because of their intriguing physical properties and potential applications in high-precision instruments. Different strategies, such as composites, solid solution and doping, have been developed as promising approaches to obtain zero thermal expansion materials. However, microstructure controlled zero thermal expansion behavior via interface or surface has not been realized. Here we report the observation of an impressive zero thermal expansion (volumetric thermal expansion coefficient, -1.41 × 10 -6  K -1 , 293-623 K) in single-crystal ferroelectric PbTiO 3 fibers with large-scale faceted and enclosed mesopores. The zero thermal expansion behavior is attributed to a synergetic effect of positive thermal expansion near the mesopores due to the oxygen-based polarization screening and negative thermal expansion from an intrinsic ferroelectricity. Our results show that a fascinating surface construction in negative thermal expansion ferroelectric materials could be a promising strategy to realize zero thermal expansion.

Surface-Casting Synthesis of Mesoporous Zirconia with a CMK-5-Like Structure and High Surface Area.

PubMed

Gu, Dong; Schmidt, Wolfgang; Pichler, Christian M; Bongard, Hans-Josef; Spliethoff, Bernd; Asahina, Shunsuke; Cao, Zhengwen; Terasaki, Osamu; Schüth, Ferdi

2017-09-04

About 15 years ago, the Ryoo group described the synthesis of CMK-5, a material consisting of a hexagonal arrangement of carbon nanotubes. Extension of the surface casting synthesis to oxide compositions, however, was not possible so far, in spite of many attempts. Here it is demonstrated, that crystalline mesoporous hollow zirconia materials with very high surface areas up to 400 m 2  g -1 , and in selected cases in the form of CMK-5-like, are indeed accessible via such a surface casting process. The key for the successful synthesis is an increased interaction between the silica hard template surface and the zirconia precursor species by using silanol group-rich mesoporous silica as a hard template. The surface areas of the obtained zirconias exceed those of conventionally hard-templated ones by a factor of two to three. The surface casting process seems to be applicable also to other oxide materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrogen Bonding-Mediated Microphase Separation during the Formation of Mesoporous Novolac-Type Phenolic Resin Templated by the Triblock Copolymer, PEO-b-PPO-b-PEO

PubMed Central

Chu, Wei-Cheng; Chiang, Shih-Fan; Li, Jheng-Guang; Kuo, Shiao-Wei

2013-01-01

After blending the triblock copolymer, poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (PEO-b-PPO-b-PEO) with novolac-type phenolic resin, Fourier transform infrared spectroscopy revealed that the ether groups of the PEO block were stronger hydrogen bond acceptors for the OH groups of phenolic resin than were the ether groups of the PPO block. Thermal curing with hexamethylenetetramine as the curing agent resulted in the triblock copolymer being incorporated into the phenolic resin, forming a nanostructure through a mechanism involving reaction-induced microphase separation. Mild pyrolysis conditions led to the removal of the PEO-b-PPO-b-PEO triblock copolymer and formation of mesoporous phenolic resin. This approach provided a variety of composition-dependent nanostructures, including disordered wormlike, body-centered-cubic spherical and disorder micelles. The regular mesoporous novolac-type phenolic resin was formed only at a phenolic content of 40–60 wt %, the result of an intriguing balance of hydrogen bonding interactions among the phenolic resin and the PEO and PPO segments of the triblock copolymer. PMID:28788378

Vanadium-substituted heteropolyacids immobilized on amine- functionalized mesoporous MCM-41: A recyclable catalyst for selective oxidation of alcohols with H{sub 2}O{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Xinbo; Wang, Danjun; College of Chemistry Chemical Engineering, Yanan University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan'an 716000

2014-09-15

Graphical abstract: Vanadium-substituted phosphotungstic acids are immobilized on amine- functionalized mesoporous MCM-41 and the hybrid catalyst is proved to be a highly efficient solid catalyst for the oxidation of aromatic alcohols to the corresponding carbonyl compounds with H{sub 2}O{sub 2}, featured by the high conversion and selectivity, easy recovery, and quite steady reuse. - Highlights: • Vanadium-substituted phosphotungstic acid immobilized on amine-functionalized mesoporous MCM-41 are prepared. • HPAs were fixed on the inner surface of mesoporous MCM-41 by chemical bonding to aminosilane groups. • The hybrid catalyst showed much higher catalytic activity than the pure HPAs. • The hybrid catalystmore » is a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols. - Abstract: New hybrid materials of vanadium-substituted phosphotungstic acids (VHPW) immobilized on amine-functionalized mesoporous MCM-41 (VHPW/MCM-41/NH{sub 2}) are prepared and characterized by FT-IR, XRD, N{sub 2} adsorption, elemental analysis, SEM and TEM for their structural integrity and physicochemical properties. It is found that the structure of the heteropolyacids is retained upon immobilization over mesoporous materials. The catalytic activities of these hybrid materials are tested in the selective oxidation of alcohols to the carbonyl products with 30% aqueous H{sub 2}O{sub 2} as oxidant in toluene. The catalytic activities of different number of vanadium-substituted phosphotungstic acid are investigated, and among the catalysts, H{sub 5}[PV{sub 2}W{sub 10}O{sub 40}] immobilized on amine-functionalized MCM-41 exhibits the highest activity with 97% conversion and 99% selectivity in the oxidation of benzyl alcohol to benzaldehyde. The hybrid catalyst is proved to be a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols to the corresponding aldehydes with H{sub 2}O{sub 2}.« less

Diffusion of aromatic hydrocarbons in hierarchical mesoporous H-ZSM-5 zeolite

DOE PAGES

Bu, Lintao; Nimlos, Mark R.; Robichaud, David J.; ...

2018-02-08

Hierarchical mesoporous zeolites exhibit higher catalytic activities and longer lifetime compared to the traditional microporous zeolites due to improved diffusivity of substrate molecules and their enhanced access to the zeolite active sites. Understanding diffusion of biomass pyrolysis vapors and their upgraded products in such materials is fundamentally important during catalytic fast pyrolysis (CFP) of lignocellulosic biomass, since diffusion makes major contribution to determine shape selectivity and product distribution. However, diffusivities of biomass relevant species in hierarchical mesoporous zeolites are poorly characterized, primarily due to the limitations of the available experimental technology. In this work, molecular dynamics (MD) simulations are utilizedmore » to investigate the diffusivities of several selected coke precursor molecules, benzene, naphthalene, and anthracene, in hierarchical mesoporous H-ZSM-5 zeolite. The effects of temperature and size of mesopores on the diffusivity of the chosen model compounds are examined. The simulation results demonstrate that diffusion within the microspores as well as on the external surface of mesoporous H-ZSM-5 dominates only at low temperature. At pyrolysis relevant temperatures, mass transfer is essentially conducted via diffusion along the mesopores. Additionally, the results illustrate the heuristic diffusion model, such as the extensively used Knudsen diffusion, overestimates the diffusion of bulky molecules in the mesopores, thus making MD simulation a powerful and compulsory approach to explore diffusion in zeolites.« less

Mesoporous-silica films, fibers, and powders by evaporation

DOEpatents

Bruinsma, Paul J.; Baskaran, Suresh; Bontha, Jagannadha R.; Liu, Jun

2008-05-06

This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).

Mesoporous-silica films, fibers, and powders by evaporation

DOEpatents

Bruinsma, Paul J.; Baskaran, Suresh; Bontha, Jagannadha R.; Liu, Jun

1999-01-01

This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).

Mesoporous-silica films, fibers, and powders by evaporation

DOEpatents

Bruinsma, P.J.; Baskaran, S.; Bontha, J.R.; Liu, J.

1999-07-13

This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s). 24 figs.

Hybrid mesoporous-silica materials functionalized by Pt(II) complexes: correlation between the spatial distribution of the active center, photoluminescence emission, and photocatalytic activity.

PubMed

Mori, Kohsuke; Watanabe, Kentaro; Terai, Yoshikazu; Fujiwara, Yasufumi; Yamashita, Hiromi

2012-09-03

[Pt(tpy)Cl]Cl (tpy: terpyridine) was successfully anchored to a series of mesoporous-silica materials that were modified with (3-aminopropyl)triethoxysilane with the aim of developing new inorganic-organic hybrid photocatalysts. Herein, the relationship between the luminescence characteristics and photocatalytic activities of these materials is examined as a function of Pt loading to define the spatial distribution of the Pt complex in the mesoporous channel. At low Pt loading, the Pt complex is located as an isolated species and exhibits strong photoluminescence emission at room temperature owing to metal-to-ligand charge-transfer ((3)MLCT) transitions (at about 530 nm). Energy- and/or electron-transfer from (3)MLCT to O(2) generate potentially active oxygen species, which are capable of promoting the selective photooxidation of styrene derivatives. On the other hand, short Pt···Pt interactions are prominent at high loading and the metal-metal-to-ligand charge-transfer ((3)MMLCT) transition is at about 620 nm. Such Pt complexes, which are situated close to each other, efficiently catalyze H(2)-evolution reactions in aqueous media in the presence of a sacrificial electron donor (EDTA) under visible-light irradiation. This study also investigates the effect of nanoconfinement on anchored guest complexes by considering the differences between the pore dimensions and structures of mesoporous-silica materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New triethoxysilylated 10-vertex closo-decaborate clusters. Synthesis and controlled immobilization into mesoporous silica.

PubMed

Abi-Ghaida, Fatima; Laila, Zahra; Ibrahim, Ghassan; Naoufal, Daoud; Mehdi, Ahmad

2014-09-14

Novel silylated hydroborate clusters comprising the closo-decaborate cage were prepared and characterized by (1)H, (13)C, (11)B, (29)Si NMR and mass spectroscopy ESI. The synthesis of such silylated clusters was achieved using reactive derivatives of [B10H10](2-), [1-B10H9N2](-) and [2-B10H9CO](-). These silylated decaborate clusters constitute a new class of precursors that can be covalently anchored onto various silica supports without any prior surface modification. As a proof of concept, the synthesized precursors were successfully anchored on mesoporous silica, SBA-15 type, in different percentages, where the mesoporous material retained its structure. All materials modified with closo-decaborate were characterized by (11)B and (29)Si solid state NMR, XRD, TEM and nitrogen sorption.

Synthesis and Characterization of Bionanoparticle-Silica Composites and Mesoporous Silica with Large Pores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niu, Z.; Yang, L.; Kabisatpathy, S.

2009-03-24

A sol-gel process has been developed to incorporate bionanoparticles, such as turnip yellow mosaic virus, cowpea mosaic virus, tobacco mosaic virus, and ferritin into silica, while maintaining the integrity and morphology of the particles. The structures of the resulting materials were characterized by transmission electron microscopy, small angle X-ray scattering, and N{sub 2} adsorption-desorption analysis. The results show that the shape and surface morphology of the bionanoparticles are largely preserved after being embedded into silica. After removal of the bionanoparticles by calcination, mesoporous silica with monodisperse pores, having the shape and surface morphology of the bionanoparticles replicated inside the silica,more » was produced,. This study is expected to lead to both functional composite materials and mesoporous silica with structurally well-defined large pores.« less

Controlled release of ibuprofen by meso–macroporous silica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santamaría, E., E-mail: esthersantamaria@ub.edu; Maestro, A.; Porras, M.

2014-02-15

Structured meso–macroporous silica was successfully synthesized from an O/W emulsion using decane as a dispersed phase. Sodium silicate solution, which acts as a silica source and a poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (EO{sub 19}PO{sub 39}EO{sub 19}) denoted as P84 was used in order to stabilize the emulsion and as a mesopore template. The materials obtained were characterized through transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angle X-ray diffraction scattering (SAXS) and nitrogen adsorption–desorption isotherms. Ibuprofen (IBU) was selected as the model drug and loaded into ordered meso–macroporous materials. The effect of the materials’ properties on IBU drug loading and releasemore » was studied. The results showed that the loading of IBU increases as the macropore presence in the material is increased. The IBU adsorption process followed the Langmuir adsorption isotherm. A two-step release process, consisting of an initial fast release and then a slower release was observed. Macropores enhanced the adsorption capacity of the material; this was probably due to the fact that they allowed the drug to access internal pores. When only mesopores were present, ibuprofen was probably adsorbed on the mesopores close to the surface. Moreover, the more macropore present in the material, the slower the release behaviour observed, as the ibuprofen adsorbed in the internal pores had to diffuse along the macropore channels up to the surface of the material. The material obtained from a highly concentrated emulsion was functionalized with amino groups using two methods, the post-grafting mechanism and the co-condensation mechanism. Both routes improve IBU adsorption in the material and show good behaviour as a controlled drug delivery system. - Graphical abstract: Ibuprofen release profiles for the materials obtained from samples P84{sub m}eso (black diamonds), P84{sub 2}0% (white squares), P84{sub 5}0% (black triangles), P84{sub 7}5% (white diamonds), P84{sub 7}5% functionalized by grafting (black squares) and P84{sub 7}5% functionalized by co-condensation method (white triangles). Display Omitted - Highlights: • Ordered meso–macroporous material is used as a controlled delivery system for ibuprofen. • Incorporation of macropores in mesoporous silica improves ibuprofen adsorption. • Meso–macroporous structures provide a lower delivery than mesoporous silica. • APTES functionalization in meso–macroporous materials improves ibuprofen adsorption and delivery behaviour.« less

Cyclic voltammetry modeling of proton transport effects on redox charge storage in conductive materials: application to a TiO2 mesoporous film.

PubMed

Kim, Y S; Balland, V; Limoges, B; Costentin, C

2017-07-21

Cyclic voltammetry is a particularly useful tool for characterizing charge accumulation in conductive materials. A simple model is presented to evaluate proton transport effects on charge storage in conductive materials associated with a redox process coupled with proton insertion in the bulk material from an aqueous buffered solution, a situation frequently encountered in metal oxide materials. The interplay between proton transport inside and outside the materials is described using a formulation of the problem through introduction of dimensionless variables that allows defining the minimum number of parameters governing the cyclic voltammetry response with consideration of a simple description of the system geometry. This approach is illustrated by analysis of proton insertion in a mesoporous TiO 2 film.

Cryo-Milling and the Hydrogen Storage Properties of NaAlH4

NASA Astrophysics Data System (ADS)

Feller, Kevin; Dobbins, Tabbetha

2013-03-01

High energy ball milling of metal hydrides is a common way to both introduce catalysts (e.g. TiCl3) and to simultaneously increase the surface area. Both catalysis and increased surface area improve hydrogen storage capacity of the material. Nanostructuring of hydrides by depositing them into mesoporous templates (such as anodized alumina, MOFs, and SBA-15) has become a common way to increase surface area. However, the mesoporous template does not add hydrogen storage capacity--and thus, tends to decreased overall storage weight percent for the nanostructured hydride material. As with most materials, hydrides become brittle at low temperatures and will tend to fracture more readily. We will process Sodium Aluminum Hydride (NaAlH4) using cryogenic high energy ball milling using an in-house modified chamber SPEX Certiprep M8000 mixer/mill in order to gain a nanostructured hydride without mesoporous template material. Details of the modified mixer mill design will be presented. Ultimately, our planned future work is to study the resultant material using x-ray diffraction (Scherrer method for crystallite size), absorption/desorption temperature programmed desorption (TPD), and ultrasmall-angle x-ray scattering (USAXS) microstructural quantification to understand the role of cryomilling on enhancing the material's ability to store (and release) hydrogen.

Fluorescent and Magnetic Mesoporous Hybrid Material: A Chemical and Biological Nanosensor for Hg2+ Ions

PubMed Central

Suresh, Moorthy; Anand, Chokkalingam; Frith, Jessica E.; Dhawale, Dattatray S.; Subramaniam, Vishnu P.; Strounina, Ekaterina; Sathish, Clastinrusselraj I.; Yamaura, Kazunari; Cooper-White, Justin J.; Vinu, Ajayan

2016-01-01

We introduce “sense, track and separate” approach for the removal of Hg2+ ion from aqueous media using highly ordered and magnetic mesoporous ferrosilicate nanocages functionalised with rhodamine fluorophore derivative. These functionalised materials offer both fluorescent and magnetic properties in a single system which help not only to selectively sense the Hg2+ ions with a high precision but also adsorb and separate a significant amount of Hg2+ ion in aqueous media. We demonstrate that the magnetic affinity of these materials, generated from the ultrafine γ-Fe2O3 nanoparticles present inside the nanochannels of the support, can efficiently be used as a fluorescent tag to sense the Hg2+ ions present in NIH3T3 fibroblasts live cells and to track the movement of the cells by external magnetic field monitored using confocal fluorescence microscopy. This simple approach of introducing multiple functions in the magnetic mesoporous materials raise the prospect of creating new advanced functional materials by fusing organic, inorganic and biomolecules to create advanced hybrid nanoporous materials which have a potential use not only for sensing and the separation of toxic metal ions but also for cell tracking in bio-separation and the drug delivery. PMID:26911660

Growth of 2D Mesoporous Polyaniline with Controlled Pore Structures on Ultrathin MoS2 Nanosheets by Block Copolymer Self-Assembly in Solution.

PubMed

Tian, Hao; Zhu, Shuyan; Xu, Fugui; Mao, Wenting; Wei, Hao; Mai, Yiyong; Feng, Xinliang

2017-12-20

The development of versatile strategies toward two-dimensional (2D) porous nanocomposites with tunable pore structures draws immense scientific attention in view of their attractive physiochemical properties and a wide range of promising applications. This paper describes a self-assembly approach for the directed growth of mesoporous polyaniline (PANi) with tunable pore structures and sizes on ultrathin freestanding MoS 2 nanosheets in solution, which produces 2D mesoporous PANi/MoS 2 nanocomposites. The strategy employs spherical and cylindrical micelles, which are formed by the controlled solution self-assembly of block copolymers, as the soft templates for the construction of well-defined spherical and cylindrical mesopores in the 2D PANi/MoS 2 nanocomposites, respectively. With potential applications as supercapacitor electrode materials, the resultant 2D composites show excellent capacitive performance with a maximum capacitance of 500 F g -1 at a current density of 0.5 A g -1 , good rate performance, as well as outstanding stability for charge-discharge cycling. Moreover, the 2D mesoporous nanocomposites offer an opportunity for the study on the influence of different pore structures on their capacitive performance, which helps to understand the pore structure-property relationship of 2D porous electrode materials and to achieve their electrochemical performance control.

Cubic mesoporous Ag@CN: a high performance humidity sensor.

PubMed

Tomer, Vijay K; Thangaraj, Nishanthi; Gahlot, Sweta; Kailasam, Kamalakannan

2016-12-01

The fabrication of highly responsive, rapid response/recovery and durable relative humidity (%RH) sensors that can precisely monitor humidity levels still remains a considerable challenge for realizing the next generation humidity sensing applications. Herein, we report a remarkably sensitive and rapid %RH sensor having a reversible response using a nanocasting route for synthesizing mesoporous g-CN (commonly known as g-C 3 N 4 ). The 3D replicated cubic mesostructure provides a high surface area thereby increasing the adsorption, transmission of charge carriers and desorption of water molecules across the sensor surfaces. Owing to its unique structure, the mesoporous g-CN functionalized with well dispersed catalytic Ag nanoparticles exhibits excellent sensitivity in the 11-98% RH range while retaining high stability, negligible hysteresis and superior real time %RH detection performances. Compared to conventional resistive sensors based on metal oxides, a rapid response time (3 s) and recovery time (1.4 s) were observed in the 11-98% RH range. Such impressive features originate from the planar morphology of g-CN as well as unique physical affinity and favourable electronic band positions of this material that facilitate water adsorption and charge transportation. Mesoporous g-CN with Ag nanoparticles is demonstrated to provide an effective strategy in designing high performance %RH sensors and show great promise for utilization of mesoporous 2D layered materials in the Internet of Things and next generation humidity sensing applications.

A green surfactant-assisted synthesis of hierarchical TS-1 zeolites with excellent catalytic properties for oxidative desulfurization.

PubMed

Du, Shuting; Li, Fen; Sun, Qiming; Wang, Ning; Jia, Mingjun; Yu, Jihong

2016-02-25

Hierarchical TS-1 zeolites with uniform intracrystalline mesopores have been successfully synthesized through the hydrothermal method by using the green and cheap surfactant Triton X-100 as the mesoporous template. The resultant materials exhibit remarkably enhanced catalytic activity in oxidative desulfurization reactions compared to the conventional TS-1 zeolite.

A mesoporous hydrogen-bonded organic-inorganic framework bearing the isopolymolybdate [Mo36O112(OH2)16]8-.

PubMed

Atencio, Reinaldo; Briceño, Alexander; Galindo, Xacvier

2005-02-07

The mesoporous H-bonded organic-inorganic hybrid material is built up from the assembly of the isopolymolybdate [Mo36O112(OH2)16]8- and H2bipy2+, which displays large interconnected cavities and exhibits a reversible water sorption behaviour while maintaining its striking crystal integrity.

Oriented and ordered mesoporous ZrO{sub 2}/TiO{sub 2} fibers with well-organized linear and spring structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Luyi, E-mail: zhuly@sdu.edu.cn; Liu, Benxue; Qin, Weiwei, E-mail: jiuyuan.1001@163.com

Graphical abstract: The ultra-stable order mesoporous ZrO{sub 2}/TiO{sub 2} fibers with well-organized linear and spring structure and large surface area under higher temperatures were prepared by a simple EISA process. - Highlights: • The ZrO{sub 2}/TiO{sub 2} fibers were prepared by EISA process combined with steam heat-treatment. • The mesoporous ZrO{sub 2}/TiO{sub 2} fibers have well-organized linear and spring structure. • The fibers were composed of oval rod nanocrystals of ZrTiO{sub 4}. - Abstract: The ultra-stable order mesoporous ZrO{sub 2}/TiO{sub 2} fibers with well-organized linear and spring structure and large surface areas under higher temperatures were prepared by a (simplemore » evaporation-induced assembly) EISA process. The preparation, microstructures and formation processes were characterized by Fourier transformation infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N{sub 2} adsorption–absorption measurements. The fibers take on pinstripe configuration which is very orderly along or perpendicular to the axial direction of the fibers. The diameters of the pinstripe are in the region of 200–400 nm and arranges regularly, which are composed of oval rod nanocrystals of ZrTiO{sub 4}.« less

Effect of polyvinylpyrrolidone on mesoporous silica morphology and esterification of lauric acid with 1-butanol catalyzed by immobilized enzyme

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jinyu; Zhou, Guowei, E-mail: guoweizhou@hotmail.com; Jiang, Bin

2014-05-01

Mesoporous silica materials with a range of morphology evolution, i.e., from curved rod-shaped mesoporous silica to straight rod-shaped mesoporous silica, were successfully prepared using polyvinylpyrrolidone (PVP) and triblock copolymer as dual template. The effects of PVP molecular weight and concentration on mesoporous silica structure parameters were studied. Results showed that surface area and pore volume continuously decreased with increased PVP molecular weight. Mesoporous silica prepared with PVP K30 also possessed larger pore diameter, interplanar spacing (d{sub 100}), and cell parameter (a{sub 0}) than that prepared with PVP K15 and PVP K90. In addition, with increased PVP concentration, d{sub 100} andmore » a{sub 0} continuously decreased. The mechanism of morphology evolution caused by the change in PVP concentration was investigated. The conversion rate of lauric acid with 1-butanol catalyzed by immobilized Porcine pancreatic lipase (PPL) was also evaluated. Results showed that PPL immobilized on amino-functionalized straight rod-shaped mesoporous silica maintained 50% of its esterification conversion rate even after five cycles of use with a maximum conversion rate was about 90.15%. - Graphical abstract: Curved rod-shaped mesoporous silica can be obtained at low and the highest PVP concentration, while straight rod-shaped mesoporous silica can be obtained at higher PVP concentration. - Highlights: • Mesoporous silica with morphology evolution from CRMS to SRMS were prepared. • Effects of PVP molecular weight and concentration on silica morphology were studied. • A possible mechanism for the formation of morphology evolution SiO{sub 2} was proposed. • Esterification of lauric acid with 1-butanol catalyzed by immobilized PPL.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bu, Lintao; Nimlos, Mark R.; Robichaud, David J.

Hierarchical mesoporous zeolites exhibit higher catalytic activities and longer lifetime compared to the traditional microporous zeolites due to improved diffusivity of substrate molecules and their enhanced access to the zeolite active sites. Understanding diffusion of biomass pyrolysis vapors and their upgraded products in such materials is fundamentally important during catalytic fast pyrolysis (CFP) of lignocellulosic biomass, since diffusion makes major contribution to determine shape selectivity and product distribution. However, diffusivities of biomass relevant species in hierarchical mesoporous zeolites are poorly characterized, primarily due to the limitations of the available experimental technology. In this work, molecular dynamics (MD) simulations are utilizedmore » to investigate the diffusivities of several selected coke precursor molecules, benzene, naphthalene, and anthracene, in hierarchical mesoporous H-ZSM-5 zeolite. The effects of temperature and size of mesopores on the diffusivity of the chosen model compounds are examined. The simulation results demonstrate that diffusion within the microspores as well as on the external surface of mesoporous H-ZSM-5 dominates only at low temperature. At pyrolysis relevant temperatures, mass transfer is essentially conducted via diffusion along the mesopores. Additionally, the results illustrate the heuristic diffusion model, such as the extensively used Knudsen diffusion, overestimates the diffusion of bulky molecules in the mesopores, thus making MD simulation a powerful and compulsory approach to explore diffusion in zeolites.« less

Synthesis and Characterization of Silver-Doped Mesoporous Bioactive Glass and Its Applications in Conjunction with Electrospinning

PubMed Central

Ciraldo, Francesca E.; Goldmann, Wolfgang H.

2018-01-01

Since they were first developed in 2004, mesoporous bioactive glasses (MBGs) rapidly captured the interest of the scientific community thanks to their numerous beneficial properties. MBGs are synthesised by a combination of the sol–gel method with the chemistry of surfactants to obtain highly mesoporous (pore size from 5 to 20 nm) materials that, owing to their high surface area and ordered structure, are optimal candidates for controlled drug-delivery systems. In this work, we synthesised and characterised a silver-containing mesoporous bioactive glass (Ag-MBG). It was found that Ag-MBG is a suitable candidate for controlled drug delivery, showing a perfectly ordered mesoporous structure ideal for the loading of drugs together with optimal bioactivity, sustained release of silver from the matrix, and fast and strong bacterial inhibition against both Gram-positive and Gram-negative bacteria. Silver-doped mesoporous glass particles were used in three electrospinning-based techniques to produce PCL/Ag-MBG composite fibres, to coat bioactive glass scaffolds (via electrospraying), and for direct sol electrospinning. The results obtained in this study highlight the versatility and efficacy of Ag-substituted mesoporous bioactive glass and encourage further studies to characterize the biological response to Ag-MBG-based antibacterial controlled-delivery systems for tissue-engineering applications. PMID:29710768

Effective Enrichment and Mass Spectrometry Analysis of Phosphopeptides Using Mesoporous Metal Oxide Nanomaterials

PubMed Central

Nelson, Cory A.; Szczech, Jeannine R.; Dooley, Chad J.; Xu, Qingge; Lawrence, Matthew J.; Zhu, Haoyue; Jin, Song; Ge, Ying

2010-01-01

Mass spectrometry (MS)-based phosphoproteomics remains challenging due to the low abundance of phosphoproteins and substoichiometric phosphorylation. This demands better methods to effectively enrich phosphoproteins/peptides prior to MS analysis. We have previously communicated the first use of mesoporous zirconium oxide (ZrO2) nanomaterials for effective phosphopeptide enrichment. Here we present the full report including the synthesis, characterization, and application of mesoporous titanium dioxide (TiO2), ZrO2, and hafnium oxide (HfO2) in phosphopeptide enrichment and MS analysis. Mesoporous ZrO2 and HfO2 are demonstrated to be superior to TiO2 for phosphopeptide enrichment from a complex mixture with high specificity (>99%), which could almost be considered as “a purification”, mainly because of the extremely large active surface area of mesoporous nanomaterials. A single enrichment and Fourier transform MS analysis of phosphopeptides digested from a complex mixture containing 7% of α-casein identified 21 out of 22 phosphorylation sites for α-casein. Moreover, the mesoporous ZrO2 and HfO2 can be reused after a simple solution regeneration procedure with comparable enrichment performance to that of fresh materials. Mesoporous ZrO2 and HfO2 nanomaterials hold great promise for applications in MS-based phosphoproteomics. PMID:20704311

Mesoporous activated carbon from corn stalk core for lithium ion batteries

NASA Astrophysics Data System (ADS)

Li, Yi; Li, Chun; Qi, Hui; Yu, Kaifeng; Liang, Ce

2018-04-01

A novel mesoporous activated carbon (AC) derived from corn stalk core is prepared via a facile and effective method which including the decomposition and carbonization of corn stalk core under an inert gas atmosphere and further activation process with KOH solution. The mesoporous activated carbon (AC) is characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) measurements. These biomass waste derived from activated carbon is proved to be promising anode materials for high specific capacity lithium ion batteries. The activated carbon anode possesses excellent reversible capacity of 504 mAh g-1 after 100 cycles at 0.2C. Compared with the unactivated carbon (UAC), the electrochemical performance of activated carbon is significantly improved due to its mesoporous structure.

Potential of hybrid functionalized meso-porous materials for the separation and immobilization of radionuclides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luca, V.

2013-07-01

Functionalized meso-porous materials are a class of hybrid organic-inorganic material in which a meso-porous metal oxide framework is functionalized with multifunctional organic molecules. These molecules may contain one or more anchor groups that form strong bonds to the pore surfaces of the metal oxide framework and free functional groups that can impart and or modify the functionality of the material such as for binding metal ions in solution. Such materials have been extensively studied over the past decade and are of particular interest in absorption applications because of the tremendous versatility in choosing the composition and architecture of the metalmore » oxide framework and the nature of the functional organic molecule as well as the efficient mass transfer that can occur through a well-designed hierarchically porous network. A sorbent for nuclear applications would have to be highly selective for particular radio nuclides, it would need to be hydrolytically and radiolytically stable, and it would have to possess reasonable capacity and fast kinetics. The sorbent would also have to be available in a form suitable for use in a column. Finally, it would also be desirable if once saturated with radio nuclides, the sorbent could be recycled or converted directly into a ceramic or glass waste form suitable for direct repository disposal or even converted directly into a material that could be used as a transmutation target. Such a cradle-to- grave strategy could have many benefits in so far as process efficiency and the generation of secondary wastes are concerned.This paper will provide an overview of work done on all of the above mentioned aspects of the development of functionalized meso-porous adsorbent materials for the selective separation of lanthanides and actinides and discuss the prospects for future implementation of a cradle-to-grave strategy with such materials. (author)« less

Surface engineering on mesoporous silica chips for enriching low molecular weight phosphorylated proteins

NASA Astrophysics Data System (ADS)

Hu, Ye; Peng, Yang; Lin, Kevin; Shen, Haifa; Brousseau, Louis C., III; Sakamoto, Jason; Sun, Tong; Ferrari, Mauro

2011-02-01

Phosphorylated peptides and proteins play an important role in normal cellular activities, e.g., gene expression, mitosis, differentiation, proliferation, and apoptosis, as well as tumor initiation, progression and metastasis. However, technical hurdles hinder the use of common fractionation methods to capture phosphopeptides from complex biological fluids such as human sera. Herein, we present the development of a dual strategy material that offers enhanced capture of low molecular weight phosphoproteins: mesoporous silica thin films with precisely engineered pore sizes that sterically select for molecular size combined with chemically selective surface modifications (i.e. Ga3+, Ti4+ and Zr4+) that target phosphoroproteins. These materials provide high reproducibility (CV = 18%) and increase the stability of the captured proteins by excluding degrading enzymes, such as trypsin. The chemical and physical properties of the composite mesoporous thin films were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and ellipsometry. Using mass spectroscopy and biostatistics analysis, the enrichment efficiency of different metal ions immobilized on mesoporous silica chips was investigated. The novel technology reported provides a platform capable of efficiently profiling the serum proteome for biomarker discovery, forensic sampling, and routine diagnostic applications.Phosphorylated peptides and proteins play an important role in normal cellular activities, e.g., gene expression, mitosis, differentiation, proliferation, and apoptosis, as well as tumor initiation, progression and metastasis. However, technical hurdles hinder the use of common fractionation methods to capture phosphopeptides from complex biological fluids such as human sera. Herein, we present the development of a dual strategy material that offers enhanced capture of low molecular weight phosphoproteins: mesoporous silica thin films with precisely engineered pore sizes that sterically select for molecular size combined with chemically selective surface modifications (i.e. Ga3+, Ti4+ and Zr4+) that target phosphoroproteins. These materials provide high reproducibility (CV = 18%) and increase the stability of the captured proteins by excluding degrading enzymes, such as trypsin. The chemical and physical properties of the composite mesoporous thin films were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and ellipsometry. Using mass spectroscopy and biostatistics analysis, the enrichment efficiency of different metal ions immobilized on mesoporous silica chips was investigated. The novel technology reported provides a platform capable of efficiently profiling the serum proteome for biomarker discovery, forensic sampling, and routine diagnostic applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c0nr00720j

Effects of catalyst pore structure and acid properties on the dehydration of glycerol.

PubMed

Choi, Youngbo; Park, Hongseok; Yun, Yang Sik; Yi, Jongheop

2015-03-01

Hierarchical porous catalysts have recently attracted increasing interest because of the enhanced accessibility to active sites on such materials. In this context, previously reported hierarchically mesoporous ASN and ASPN materials are evaluated by applying them to the dehydration of glycerol, and demonstrate excellent catalytic performance. In addition, a comprehensive understanding of the effects of pore structures and the acid properties on the reaction through comparative studies with microporous HZSM-5 and mesoporous AlMCM-41 is provided. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low-Temperature Fluorination of Soft-Templated Mesoporous Carbons for a High-Power Lithium/Carbon Fluoride Battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fulvio, Pasquale F.; Brown, Suree S.; Adcock, Jamie

Soft-templated mesoporous carbons and activated mesoporous carbons were fluorinated using elemental fluorine between room temperature and 235 °C. The mesoporous carbons were prepared via self-assembly synthesis of phloroglucinol–formaldehyde as a carbon precursor in the presence of triblock ethylene oxide–propylene oxide–ethylene oxide copolymer BASF Pluronic F127 as the template. The F/C ratios ranged from ~0.15 to 0.75 according to gravimetric, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy analysis. Materials have mesopore diameters up to 11 nm and specific surface areas as high as 850 m² g⁻¹ after fluorination as calculated from nitrogen adsorption isotherms at -196 °C. Furthermore, the materialsmore » exhibit higher discharge potentials and energy and power densities as well as faster reaction kinetics under high current densities than commercial carbon fluorides with similar fluorine contents when tested as cathodes for Li/CF x batteries.« less

Ordered mesoporous silica to enhance the bioavailability of poorly water-soluble drugs: Proof of concept in man.

PubMed

Bukara, Katarina; Schueller, Laurent; Rosier, Jan; Martens, Mark A; Daems, Tinne; Verheyden, Loes; Eelen, Siemon; Van Speybroeck, Michiel; Libanati, Cristian; Martens, Johan A; Van Den Mooter, Guy; Frérart, Françoise; Jolling, Koen; De Gieter, Marjan; Bugarski, Branko; Kiekens, Filip

2016-11-01

Formulating poorly water soluble drugs using ordered mesoporous silica materials is an emerging approach to tackle solubility-related bioavailability problems. The current study was conducted to assess the bioavailability-enhancing potential of ordered mesoporous silica in man. In this open-label, randomized, two-way cross-over study, 12 overnight fasted healthy volunteers received a single dose of fenofibrate formulated with ordered mesoporous silica or a marketed product based on micronized fenofibrate. Plasma concentrations of fenofibric acid, the pharmacologically active metabolite of fenofibrate, were monitored up to 96h post-dose. The rate (C max /dose increased by 77%; t max reduced by 0.75h) and extent of absorption (AUC 0-24h /dose increased by 54%) of fenofibrate were significantly enhanced following administration of the ordered mesoporous silica based formulation. The results of this study serve as a proof of concept in man for this novel formulation approach. Copyright © 2016 Elsevier B.V. All rights reserved.

The adsorption of gold, palladium and platinum from acidic chloride solutions on mesoporous carbons.

DOE PAGES

Zalupski, Peter R.; McDowell, Rocklan; Dutech, Guy

2014-08-05

Studies on the adsorption characteristics of gold, palladium and platinum on mesoporous carbon (CMK-3) and sulfur-impregnated mesoporous carbon (CMK-3/S) evaluated the benefits/drawbacks of the presence of a layer of elemental sulfur inside mesoporous carbon structures. Adsorption isotherms collected for Au(III), Pd(II) and Pt(IV) on those materials suggest that sulfur does enhance the adsorption of those metal ions in mildly acidic environment (pH 3). The isotherms collected in 1 M HCl show that the benefit of sulfur disappears due to the competing influence of large concentration of hydrogen ions on the ion-exchanging mechanism of metal ions sorption on mesoporous carbon surfaces.more » The collected acid dependencies illustrate similar adsorption characteristics for CMK-3 and CMK-3/S in 1-5 M HCl concentration range. Sorption of metal ions from diluted aqueous acidic mixtures of actual leached electronic waste demonstrated the feasibility of recovery of gold from such liquors.« less

Soft-Template Synthesis of Mesoporous Anatase TiO₂ Nanospheres and Its Enhanced Photoactivity.

PubMed

Li, Xiaojia; Zou, Mingming; Wang, Yang

2017-11-10

Highly crystalline mesoporous anatase TiO₂ nanospheres with high surface area (higher than P25 and anatase TiO₂) are prepared by a soft-template method. Despite the high specific surface area, these samples have three times lower equilibrium adsorption (<2%) than Degussa P25. The rate constant of the mesoporous anatase TiO₂ (0.024 min -1 ) reported here is 364% higher than that of P25 (0.0066 min -1 ), for the same catalytic loading. The results of oxidation-extraction photometry using several reactive oxygen species (ROS) scavengers indicated that mesoporous anatase TiO₂ generates more ROS than P25 under UV-light irradiation. This significant improvement in the photocatalytic performance of mesoporous spherical TiO₂ arises from the following synergistic effects in the reported sample: (i) high surface area; (ii) improved crystallinity; (iii) narrow pore wall thicknesses (ensuring the rapid migration of photogenerated carriers to the surface of the material); and (iv) greater ROS generation under UV-light.

Dual soft-template system based on colloidal chemistry for the synthesis of hollow mesoporous silica nanoparticles.

PubMed

Li, Yunqi; Bastakoti, Bishnu Prasad; Imura, Masataka; Tang, Jing; Aldalbahi, Ali; Torad, Nagy L; Yamauchi, Yusuke

2015-04-20

A new dual soft-template system comprising the asymmetric triblock copolymer poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-b-P2VP-b-PEO) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) is used to synthesize hollow mesoporous silica (HMS) nanoparticles with a center void of around 17 nm. The stable PS-b-P2VP-b-PEO polymeric micelle serves as a template to form the hollow interior, while the CTAB surfactant serves as a template to form mesopores in the shells. The P2VP blocks on the polymeric micelles can interact with positively charged CTA(+) ions via negatively charged hydrolyzed silica species. Thus, dual soft-templates clearly have different roles for the preparation of the HMS nanoparticles. Interestingly, the thicknesses of the mesoporous shell are tunable by varying the amounts of TEOS and CTAB. This study provides new insight on the preparation of mesoporous materials based on colloidal chemistry. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An efficient synthesis of graphenated carbon nanotubes over the tailored mesoporous molecular sieves by chemical vapor deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atchudan, R.; Department of Chemistry, CEG Campus, Anna University, Chennai 600025; Joo, Jin., E-mail: joojin@knu.ac.kr

2013-06-01

Highlights: ► Tailored 3D cubic Ni/KIT-6 with large pores was synthesized successfully. ► The new hybrid g-CNTs in large scale were synthesized using Ni/KIT-6 by CVD method. ► The use of mesoporous material by CVD method would be an ideal choice to prepare g-CNTs at reasonable cost. ► This type of g-CNTs might be a new avenue for nano-electronic applications. - Abstract: The new hybrid of graphenated carbon nanotubes (g-CNTs) was superior to either CNTs or graphene. Mesoporous 3D cubic Ni/KIT-6 were synthesized hydrothermally through organic template route and then were used as catalytic template for the production of g-CNTsmore » using acetylene as a carbon precursor by chemical vapor deposition (CVD) method. The deposited new hybrid carbon materials were purified and analyzed by various physico-chemical techniques such as XRD, TGA, SEM, TEM and Raman spectroscopy techniques. The graphitization of CNTs was confirmed by TGA and HRTEM studies. Thermal stability, surface morphology, and structural morphology of these materials were revealed by TGA, SEM and TEM analysis, respectively. Moreover, the tailored mesoporous Ni/KIT-6 molecular sieves were found to possess better quality and massive quantity of g-CNTs produced compared to other catalytic template route.« less

Recovery of silica from electronic waste for the synthesis of cubic MCM-48 and its application in preparing ordered mesoporous carbon molecular sieves using a green approach

NASA Astrophysics Data System (ADS)

Liou, Tzong-Horng

2012-07-01

The electronics industry is one of the world's fastest growing manufacturing industries. However, e-waste has become a serious pollution problem. This study reports the recovery of e-waste for preparing valuable MCM-48 and ordered mesoporous carbon for the first time. Specifically, this study adopts an alkali-extracted method to obtain sodium silicate precursors from electronic packaging resin ash. The influence of synthesis variables such as gelation pH, neutral/cationic surfactant ratio, hydrothermal treatment temperature, and calcination temperature on the mesophase of MCM-48 materials is investigated. Experimental results confirm that well-ordered cubic MCM-48 materials were synthesized in strongly acidic and strongly basic media. The resulting mesoporous silica had a high surface area of 1,317 m2/g, mean pore size of about 3.0 nm, and a high purity of 99.87 wt%. Ordered mesoporous carbon with high surface area (1,715 m2/g) and uniform pore size of CMK-1 type was successfully prepared by impregnating MCM-48 template using the resin waste. The carbon structure was sensitive to the sulfuric acid concentration and carbonization temperature. Converting e-waste into MCM-48 materials not only eliminates the disposal problem of e-waste, but also transforms industrial waste into a useful nanomaterial.

Assistant template and co-template agents in modeling mesoporous silicas and post-synthesizing organofunctionalizations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oliveira, Vaeudo V.; Airoldi, Claudio, E-mail: airoldi@iqm.unicamp.br

2012-12-15

Mesoporous SBA-16 silicas were synthesized through a direct methodology using the template (F127) combined with co-templates (ethanol and n-butanol), with tetraethylorthosilicate as the silica source. These ordered mesoporous silica were characterized by elemental analyses, infrared spectroscopy, solid-state nuclear magnetic resonance for {sup 13}C (CP/MAS) and {sup 29}Si (HP/DEC) nuclei, nitrogen sorption/desorption processes, small angle X-ray analyses (SAXS) and transmission electron microscopy (TEM). SAXS and TEM results confirmed the space group Im3m and cubic 3D symmetry, typical for highly ordered SBA-16. The sorption/desorption data for SBA-16 and when functionalized gave type IV isotherms, with hysteresis loop H2. Surface areas of 836;more » 657 and 618 m{sup 2} g{sup -1} and average pore diameters of 7.99; 8.10 and 9.85 nm, for SBA-16A, SBA-16B and SBA-16C were obtained, respectively. When functionalized the silicas presented a reduction in surface area, pore volume and pore diameter due to the pendant chains that interfere with nitrogen sorption in these measurements. The co-template ethanol favors the ordered mesopores with highest wall thicknesses. - Graphical Abstract: The mesoporous SBA-16 can be synthesized from binary (F127/TEOS) or ternary (F127/alcohol/TEOs) systems to give well-ordered mesoporous silicas. The co-templates ethanol or butanol gave the final material with highest wall thickness, mainly with ethanol. After these syntheses the pores were successfully organofunctionalized to give a good incorporation of the silylating agents. The final silicas presented of well-arranged solid characteristics as expressing by three distinct peaks, as indexed by the corresponding planes. Highlights: Black-Right-Pointing-Pointer Syntheses of mesoporous silicas by using ternary (F127/agent/TEOS) and binary (F127/TEOS) systems. Black-Right-Pointing-Pointer Use of co-templates to synthesize mesoporous silicas with larger wall thicknesses. Black-Right-Pointing-Pointer Immobilization of pendant chains inside the porous silicas. Black-Right-Pointing-Pointer Ordered mesoposous silicas as new materials for possible applications on sorption and delivering drug systems.« less

Periodic mesoporous organosilicas containing interconnected [Si(CH2)]3 rings.

PubMed

Landskron, Kai; Hatton, Benjamin D; Perovic, Doug D; Ozin, Geoffrey A

2003-10-10

A periodic mesoporous organosilica composed of interconnected three-ring [Si(CH2)]3 units built of three SiO2(CH2)2 tetrahedral subunits is reported. It represents the archetype of a previously unknown class of nanocomposite materials in which two bridging organic groups are bound to each silicon atom. It can be obtained with powder and oriented film morphologies. The nanocomposite is self-assembled from the cyclic three-ring silsesquioxane [(EtO)2Si(CH2)]3 precursor and a surfactant mesophase to give a well-ordered mesoporous framework. Low dielectric constants and good mechanical stability of the films were measured, making this material interesting for microelectronic applications. Methylene group reactivity of the three-ring precursor provides entry to a family of nanocomposites, exemplified by the synthesis and self-assembly of [(EtO)2Si(CHR)][(EtO)2Si(CH2)]2 (where R indicates iodine, bromine, or an ethyl group).

Functionalized bimodal mesoporous silicas as carriers for controlled aspirin delivery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao Lin; Sun Jihong, E-mail: jhsun@bjut.edu.cn; Li Yuzhen

The bimodal mesoporous silica modified with 3-aminopropyltriethoxysilane was performed as the aspirin carrier. The samples' structure, drug loading and release profiles were characterized with X-ray diffraction, scanning electron microscopy, N{sub 2} adsorption and desorption, Fourier transform infrared spectroscopy, TG analysis, elemental analysis and UV-spectrophotometer. For further exploring the effects of the bimodal mesopores on the drug delivery behavior, the unimodal mesoporous material MCM-41 was also modified as the aspirin carrier. Meantime, Korsmeyer-Peppas equation f{sub t}=kt{sup n} was employed to analyze the dissolution data in details. It is indicated that the bimodal mesopores are beneficial for unrestricted drug molecules diffusing andmore » therefore lead to a higher loading and faster releasing than that of MCM-41. The results show that the aspirin delivery properties are influenced considerably by the mesoporous matrix, whereas the large pore of bimodal mesoporous silica is the key point for the improved controlled-release properties. - Graphical abstract: Loading (A) and release profiles (B) of aspirin in N-BMMs and N-MCM-41 indicated that BMMs have more drug loading capacity and faster release rate than that MCM-41. Highlights: > Bimodal mesoporous silicas (BMMs) and MCM-41 modified with amino group via post-treatment procedure. > Loading and release profiles of aspirin in modified BMMs and MCM-41. > Modified BMMs have more drug loading capacity and faster release rate than that modified MCM-41.« less

Immobilization of chloroperoxidase on mesoporous materials for the oxidation of 4,6-dimethyldibenzothiophene, a recalcitrant organic sulfur compound present in petroleum fractions.

PubMed

Terrés, Eduardo; Montiel, Mayra; Le Borgne, Sylvie; Torres, Eduardo

2008-01-01

The catalytic potential of chloroperoxidase (CPO) immobilized on mesoporous materials was evaluated for the oxidation of 4,6-dimethyldibenzothiophene in water/acetonitrile mixtures. Two different types of materials were used for the immobilization: a metal containing Al-MCM-41 material with a pore size of 26 A and SBA-16 materials with three different pore sizes: 40, 90 and 117 A. The SBA-16 40 A did not retain any CPO. The nature and the pore size of the material affected the catalytic activity of the enzyme as well as its stability. Compared to the free enzyme, the thermal stability of CPO at 45 degrees C was two and three times higher than when immobilized on Al-MCM-41 and SBA-16 90 A, respectively.

One-step synthesis of amine-functionalized hollow mesoporous silica nanoparticles as efficient antibacterial and anticancer materials.

PubMed

Hao, Nanjing; Jayawardana, Kalana W; Chen, Xuan; Yan, Mingdi

2015-01-21

In this study, amine-functionalized hollow mesoporous silica nanoparticles with an average diameter of ∼100 nm and shell thickness of ∼20 nm were prepared by an one-step process. This new nanoparticulate system exhibited excellent killing efficiency against mycobacterial (M. smegmatis strain mc(2) 651) and cancer cells (A549).

Silica sacrificial layer-assisted in-plane incorporation of Au nanoparticles into mesoporous titania thin films through different reduction methods.

PubMed

Liang, Chih-Peng; Yamauchi, Yusuke; Liu, Chia-Hung; Wu, Kevin C-W

2013-06-28

This study focuses on the incorporation of gold nanoparticles (Au NPs) into our previously synthesized mesoporous titania thin films consisting of titania nanopillars and inverse mesospace (C. W. Wu, T. Ohsuna, M. Kuwabara and K. Kuroda, J. Am. Chem. Soc., 2006, 128, 4544-4545, denoted as MTTFs). Recently, mesoporous titania materials doped with noble metals such as gold have attracted considerable attention because noble metals can enhance the efficiency of mesoporous titania-based devices. In this research, we attempted to use four different reduction methods (i.e., thermal treatment, photo irradiation, liquid immersion, and vapor contacting) to introduce gold nanoparticles (Au NPs) into MTTFs. The synthesized Au@MTTFs were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We further systematically investigated the formation mechanism of gold nanoparticles on the external and internal surfaces of the MTTFs. With the assistance of a silica sacrificial layer, well-dispersed Au NPs with sizes of 4.1 nm were obtained inside the MTTF by photo irradiation. The synthesized Au@MTTF materials show great potential in various photo-electronic and photo-catalytic applications.

Microgravity Effects on Chronoamperometric Ammonia Oxidation Reaction at Platinum Nanoparticles on Modified Mesoporous Carbon Supports

NASA Astrophysics Data System (ADS)

Poventud-Estrada, Carlos M.; Acevedo, Raúl; Morales, Camila; Betancourt, Luis; Diaz, Diana C.; Rodriguez, Manuel A.; Larios, Eduardo; José-Yacaman, Miguel; Nicolau, Eduardo; Flynn, Michael; Cabrera, Carlos R.

2017-10-01

The effect of microgravity on the electrochemical oxidation of ammonia at platinum nanoparticles supported on modified mesoporous carbons (MPC) with three different pore diameters (64, 100, and 137 Å) was studied via the chronoamperometric technique in a half-cell. The catalysts were prepared by a H2 reductive process of PtCl6^{4-} in presence of the mesoporous carbon support materials. A microgravity environment was obtained with an average gravity of less than 0.02 g created aboard an airplane performing parabolic maneuvers. Results show the chronoamperommetry of the ammonia oxidation reaction in 1.0 M NH4OH at 0.60 V vs. RHE under microgravity conditions. The current density, in all three catalysts, decreased while in microgravity conditions when compared to ground based experiments. Under microgravity, all three catalysts yielded a decrease in ammonia oxidation reaction current density between 25 to 63% versus terrestrial experimental results, in time scales between 1 and 15 s. The Pt catalyst prepared with mesoporous carbon of 137 Å porous showed the smallest changes, between 25 to 48%. Nanostructuring catalyst materials have an effect on the level of current density decrease under microgravity conditions.

Mesoporous silica obtained with methyltriethoxysilane as co-precursor in alkaline medium

NASA Astrophysics Data System (ADS)

Putz, Ana-Maria; Wang, Kunzhou; Len, Adél; Plocek, Jiri; Bezdicka, Petr; Kopitsa, Gennady P.; Khamova, Tamara V.; Ianăşi, Cătălin; Săcărescu, Liviu; Mitróová, Zuzana; Savii, Cecilia; Yan, Minhao; Almásy, László

2017-12-01

Mesoporous silica particles have been synthesized by sol-gel method from tetraethoxysilane (tetraethylorthosilicate, TEOS) and methyltriethoxysilane (MTES), in ethanol and water mixture, at different ratios of the of the silica precursors. Ammonia was used as catalyst at room temperature and hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide, CTAB) as the structure directing agent. Nitrogen sorption, X-ray diffraction and small-angle neutron scattering gave information on the evolution of the gel structure and pore morphologies in the function of MTES/TEOS molar ratio. Thermogravimetric and differential thermal analysis showed that with addition of MTES the exothermic peak indicating the oxidation of the low molecular weight organic fragments shift to higher temperature. A room-temperature, one-pot synthesis of MCM-41 type materials is presented, in which the variation of the MTES concentration allows to change the hydrophobicity, preserving the specific properties materials, like the ordered pore structure, large specific surface area and high porosity. Specifically, the obtained materials had cylindrical pores, specific surface areas up to 1101 m2/g and total pore volumes up to 0.473 cm3/g. The obtained mesoporous materials are susceptible for further functionalization to improve their selective uptake of guest species in drug delivery applications.

Facile preparation of magnetic graphene double-sided mesoporous composites for the selective enrichment and analysis of endogenous peptides.

PubMed

Yin, Peng; Sun, Nianrong; Deng, Chunhui; Li, Yan; Zhang, Xiangmin; Yang, Pengyuan

2013-08-01

In this work, magnetic graphene double-sided mesoporous nanocomposites (mag-graphene@mSiO₂) were synthesized by coating a layer of mesoporous silica materials on each side of magnetic grapheme. The surfactant (CTAB) mediated sol-gel coating was performed using tetraethyl orthosilicate as the silica source. The as-made magnetic graphene double-sided mesoporous silica composites were treated with high-temperature calcination to remove the hydroxyl on the surface. The novel double-sided materials possess high surface area (167.8 cm²/g) and large pore volume (0.2 cm³/g). The highly open pore structure presents uniform pore size (3.2 nm) and structural stability. The hydrophobic interior pore walls could ensure an efficient adsorption of target molecules through hydrophobic-hydrophobic interaction. At the same time, the magnetic Fe₃O₄ particles on both sides of the materials could simplify the process of enrichment, which plays an important role in the treatment of complex biological samples. The magnetic graphene double-sided nanocomposites were successfully applied to size-selective and specific enrichment of peptides in standard peptide mixtures, protein digest solutions, and human urine samples. Finally, the novel material was applied to selective enrichment of endogenous peptides in mouse brain tissue. The enriched endogenous peptides were then analyzed by LC-MS/MS, and 409 endogenous peptides were detected and identified. The results demonstrate that the as-made mag-graphene@mSiO₂ have powerful potential for peptidome research. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of mesoporous metal oxide coated-nanocarbon hybrid materials via a polyol-mediated self-assembly process.

PubMed

Feng, Bingmei; Wang, Huixin; Wang, Dongniu; Yu, Huilong; Chu, Yi; Fang, Hai-Tao

2014-11-06

After clarifying the formation mechanism of a typical metal glycolate precipitate, Ti glycolate, in a polyol-mediated synthesis using acetone as a precipitation medium, we describe a simple template-free approach based on an ethylene glycol-mediated synthesis to fabricate mesoporous metal oxide coated-nanocarbon hybrid materials including TiO₂ coated-carbon nanotube (CNT), SnO₂ coated-CNT, Cu₂O/CuO coated-CNT and TiO₂ coated-graphene sheet (GS). In the approach, metal oxide precursors, metal glycolates, were first deposited on CNTs or GSs, and subsequently transformed to the metal oxide coatings by pyrolysis or hydrolysis. By a comparison between the characterization of two TiO₂-CNT hybrid materials using carboxylated CNTs and pristine CNTs without carboxyl groups, the driving force for initiating the deposition of metal glycolates on the carboxylated CNTs is confirmed to be the hydrogen bonding between the carboxyl groups and the polymer chains in metal glycolate sols. The electrochemical performances of the mesoporous TiO₂ coated-carboxylated CNTs and TiO₂-pristine CNT hybrid materials were investigated. The results show that the mesoporous TiO₂ coated-carboxylated CNT with a uniform core-shell nanostructure exhibits substantial improvement in the rate performance in comparison with its counterpart from 0.5 C to 100 C because of its higher electronic conductivity and shorter diffusion path for the lithium ion. At the extremely high rate of 100 C, the specific capacity of TiO₂ of the former reaches 85 mA h g(-1), twice as high as that of the latter.

Developing nanotechnology for biofuel and plant science applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valenstein, Justin

2012-01-01

This dissertation presents the research on the development of mesoporous silica based nanotechnology for applications in biofuels and plant science. Mesoporous silica nanoparticles (MSNs) have been the subject of great interest in the last two decades due to their unique properties of high surface area, tunable pore size and particle morphology. The robust nature of the silica framework is easily functionalized to make the MSNs a promising option for selective separations. Also, the independent channels that form the pores of MSN have been exploited in the use of particles as platforms for molecular delivery. Pore size and organic functionality aremore » varied to identify the ideal adsorbent material for free fatty acids (FFAs). The resulting material is able to sequester FFAs with a high degree of selectivity from a simulated solution and microalgal oil. The recyclability and industrial implications are also explored. A continuation of the previous material, further tuning of MSN pore size was investigated. Particles with a smaller diameter selectively sequester polyunsaturated free fatty acids (PUFAs) over monounsaturated FFAs and saturated FFAs. The experimental results were verified with molecular modeling. Mesoporous silica nanoparticle materials with a pore diameter of 10 nm (MSN-10) were decorated with small gold nanoparticles. The resulting materials were shown to deliver proteins and DNA into plant cells using the biolistic method.« less

Inorganic Nanocrystals Functionalized Mesoporous Silica Nanoparticles: Fabrication and Enhanced Bio-applications

NASA Astrophysics Data System (ADS)

Zhao, Tiancong; Nguyen, Nam-Trung; Xie, Yang; Sun, Xiaofei; Li, Qin; Li, Xiaomin

2017-12-01

Mesoporous SiO2 nanoparticles (MSNs) are one of the most promising materials for bio-related applications due to advantages such as good biocompatibility, tunable mesopores and large pore volume. However, unlike the inorganic nanocrystals with abundant physical properties, MSNs alone lack functional features. Thus, they are not sufficiently suitable for bio-applications that require special functions. Consequently, MSNs are often functionalized by incorporating inorganic nanocrystals, which provide a wide range of intriguing properties. This review focuses on inorganic nanocrystals functionalized MSNs, both their fabrication and bio-applications. Some of the most utilized methods for coating mesoporous silica (mSiO2) on nanoparticles were summarized. Magnetic, fluorescence and photothermal inorganic nanocrystals functionalized MSNs were taken as examples to demonstrate the bio-applications. Furthermore, asymmetry of MSNs and their effects on functions were also highlighted.

Adsorption of vitamin E on mesoporous titania nanocrystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shih, C.J., E-mail: cjshih@kmu.edu.tw; Lin, C.T.; Wu, S.M.

2010-07-15

Tri-block nonionic surfactant and titanium chloride were used as starting materials for the synthesis of mesoporous titania nanocrystallite powders. The main objective of the present study was to examine the synthesis of mesoporous titania nanocrystals and the adsorption of vitamin E on those nanocrystals using X-ray diffraction (XRD), transmission electron microscopy, and nitrogen adsorption and desorption isotherms. When the calcination temperature was increased to 300 {sup o}C, the reflection peaks in the XRD pattern indicated the presence of an anatase phase. The crystallinity of the nanocrystallites increased from 80% to 98.6% with increasing calcination temperature from 465 {sup o}C tomore » 500 {sup o}C. The N{sub 2} adsorption data and XRD data taken after vitamin E adsorption revealed that the vitamin E molecules were adsorbed in the mesopores of the titania nanocrystals.« less

Bioinspired Mesoporous Chiral Nematic Graphitic Carbon Nitride Photocatalysts modulated by Polarized Light.

PubMed

Lin, Wensheng; Hong, Wei; Sun, Lu; Yu, Di; Yu, Dingshan; Chen, Xudong

2018-01-10

Endowing materials with chirality and exploring the responses of the material under circularly polarized light (CPL) can enable further insight into the physical and chemical properties of the semiconductors to be gained, thus expanding on optoelectronic applications. Herein a bioinspired mesoporous chiral nematic graphitic carbon nitride (g-C 3 N 4 ) for efficient hydrogen evolution with polarized light modulation based on chiral nematic cellulose nanocrystal films prepared through silica templating is described. The mesoporous nematic chiral g-C 3 N 4 exhibits an ultrahigh hydrogen evolution rate of 219.9 μmol h -1 (for 20 mg catalyst), corresponding to a high enhancement factor of 55 when compared to the bulk g-C 3 N 4 under λ>420 nm irradiation. Furthermore, the chiral g-C 3 N 4 material exhibits unique photocatalytic activity modulated by CPL within the absorption region. This CPL-assisted photocatalytic regulation strategy holds great promise for a wide range of applications including optical devices, asymmetric photocatalysis, and chiral recognition/separation. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of carboxylic acid of periodic mesoporous organosilicas on the fructose-to-5-hydroxymethylfurfural conversion in dimethylsulfoxide systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dutta, Saikat; Wu, Kevin C.-W., E-mail: hmkao@cc.ncu.edu.tw, E-mail: kevinwu@ntu.edu.tw; Kao, Hsien-Ming, E-mail: hmkao@cc.ncu.edu.tw, E-mail: kevinwu@ntu.edu.tw

This manuscript presents the preparation and catalytic application of highly ordered benzene bridged periodic mesoporous organosilicas (PMOs) functionalized with carboxylic acid (–COOH) group at varied density. The COOH-functionalized PMOs were synthesized by one-step condensation of 1,4-bis (triethoxysilyl) benzene and carboxylic group containing organosilane carboxyethylsilanetriol sodium salt using Brij-76 as the template. The obtained materials were characterized by a mean of methods including powder X-ray diffraction, nitrogen adsorption-desorption, scanning- and transmission electron microscopy, and {sup 13}C solid-state nuclear magnetic resonance measurements. The potentials of the obtained PMO materials with ordered mesopores were examined as solid catalysts for the chemical conversion ofmore » fructose to 5-hydroxymethylfurfural (HMF) in an organic solvent. The results showed that COOH-functionalized PMO with 10% COOH loading exhibited best results for the fructose to HMF conversion and selectivity. The high surface area, the adequate density acid functional group, and the strength of the PMO materials contributing to a promising catalytic ability were observed.« less

Hexamethyldisilazane Removal with Mesoporous Materials Prepared from Calcium Fluoride Sludge.

PubMed

Kao, Ching-Yang; Lin, Min-Fa; Nguyen, Nhat-Thien; Tsai, Hsiao-Hsin; Chang, Luh-Maan; Chen, Po-Han; Chang, Chang-Tang

2018-05-01

A large amount of calcium fluoride sludge is generated by the semiconductor industry every year. It also requires a high amount of fuel consumption using rotor concentrators and thermal oxidizers to treat VOCs. The mesoporous adsorbent prepared by calcium fluoride sludge was used for VOCs treatment. The semiconductor industry employs HMDS to promote the adhesion of photo-resistant material to oxide(s) due to the formation of silicon dioxide, which blocks porous adsorbents. The adsorption of HMDS (Hexamethyldisiloxane) was tested with mesoporous silica materials synthesized from calcium fluoride (CF-MCM). The resulting samples were characterized by XRD, XRF, FTIR, N2-adsorption-desorption techniques. The prepared samples possessed high specific surface area, large pore volume and large pore diameter. The crystal patterns of CF-MCM were similar with Mobil composite matter (MCM-41) from TEM image. The adsorption capacity of HMDS with CF-MCM was 40 and 80 mg g-1, respectively, under 100 and 500 ppm HMDS. The effects of operation parameters, such as contact time and mixture concentration, on the performance of CF-MCM were also discussed in this study.

A Magnetically Separable, Highly Stable Enzyme System Based on Nanocomposites of Enzymes and Magnetic Nanoparticles Shipped in Hierarchically Ordered, Mesocellular, Mesoporous Silica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jungbae; Lee, Jinwoo; Na, Hyon Bin

2005-12-01

Enzymes are versatile nanoscale biocatalysts, and find increasing applications in many areas, including organic synthesis[1-3] and bioremediation.[4-5] However, the application of enzymes is often hampered by the short catalytic lifetime of enzymes and by the difficulty in recovery and recycling. To solve these problems, there have been a lot of efforts to develop effective enzyme immobilization techniques. Recent advances in nanotechnology provide more diverse materials and approaches for enzyme immobilization. For example, mesoporous materials offer potential advantages as a host of enzymes due to their well-controlled porosity and large surface area for the immobilization of enzymes.[6,7] On the other hand,more » it has been demonstrated that enzymes attached on magnetic iron oxide nanoparticles can be easily recovered using a magnet and recycled for iterative uses.[8] In this paper, we report the development of magnetically-separable and highly-stable enzyme system by the combined use of two different kinds of nanostructured materials: magnetic nanoparticles and mesoporous silica.« less

Preparation of Carbon Nanotube/TiO2 Mesoporous Hybrid Photoanode with Iron Pyrite (FeS2) Thin Films Counter Electrodes for Dye-Sensitized Solar Cell

PubMed Central

Kilic, Bayram; Turkdogan, Sunay; Astam, Aykut; Ozer, Oguz Can; Asgin, Mansur; Cebeci, Hulya; Urk, Deniz; Mucur, Selin Pravadili

2016-01-01

Multi-walled carbon nanotube (MWCNT)/TiO2 mesoporous networks can be employed as a new alternative photoanode in dye-sensitized solar cells (DSSCs). By using the MWCNT/TiO2 mesoporous as photoanodes in DSSC, we demonstrate that the MWCNT/TiO2 mesoporous photoanode is promising alternative to standard FTO/TiO2 mesoporous based DSSC due to larger specific surface area and high electrochemical activity. We also show that iron pyrite (FeS2) thin films can be used as an efficient counter electrode (CE), an alternative to the conventional high cost Pt based CE. We are able to synthesis FeS2 nanostructures utilizing a very cheap and easy hydrothermal growth route. MWCNT/TiO2 mesoporous based DSSCs with FeS2 CE achieved a high solar conversion efficiency of 7.27% under 100 mW cm−2 (AM 1.5G 1-Sun) simulated solar irradiance which is considerably (slightly) higher than that of A-CNT/TiO2 mesoporous based DSSCs with Pt CE. Outstanding performance of the FeS2 CE makes it a very promising choice among the various CE materials used in the conventional DSSC and it is expected to be used more often to achieve higher photon-to-electron conversion efficiencies. PMID:27243374

Mesoporous silica nanoparticles supported copper(II) and nickel(II) Schiff base complexes: Synthesis, characterization, antibacterial activity and enzyme immobilization

NASA Astrophysics Data System (ADS)

Tahmasbi, Leila; Sedaghat, Tahereh; Motamedi, Hossein; Kooti, Mohammad

2018-02-01

Mesoporous silica nanoparticles (MSNs) were prepared by sol-gel method and functionalized with 3-aminopropyltriethoxysilane. Schiff base grafted mesoporous silica nanoparticle was synthesized by the condensation of 2-hydroxy-3-methoxybenzaldehyde and amine-functionalized MSNs. The latter material was then treated with Cu(II) and Ni(II) salts separately to obtain copper and nickel complexes anchored mesoporous composites. The newly prepared hybrid organic-inorganic nanocomposites have been characterized by several techniques such as FT-IR, LA-XRD, FE-SEM, TEM, EDS, BET and TGA. The results showed all samples have MCM-41 type ordered mesoporous structure and functionalization occurs mainly inside the mesopore channel. The presence of all elements in synthesized nanocomposites and the coordination of Schiff base via imine nitrogen and phenolate oxygen were confirmed. MSNs and all functionalized MSNs have uniform spherical nanoparticles with a mean diameter less than 100 nm. The as-synthesized mesoporous nanocomposites were investigated for antibacterial activity against Gram-positive (B. subtilis and S. aureus) and Gram-negative (E. coli and P. aeruginosa) bacteria, as carrier for gentamicin and also for immobilization of DNase, coagulase and amylase enzymes. MSN-SB-Ni indicated bacteriocidal effect against S.aureus and all compounds were found to be good carrier for gentamicin. Results of enzyme immobilization for DNase and coagulase and α-amylase revealed that supported metal complexes efficiently immobilized enzymes.

Activated Porous Carbon Spheres with Customized Mesopores through Assembly of Diblock Copolymers for Electrochemical Capacitor.

PubMed

Tang, Jing; Wang, Jie; Shrestha, Lok Kumar; Hossain, Md Shahriar A; Alothman, Zeid Abdullah; Yamauchi, Yusuke; Ariga, Katsuhiko

2017-06-07

A series of porous carbon spheres with precisely adjustable mesopores (4-16 nm), high specific surface area (SSA, ∼2000 m 2 g -1 ), and submicrometer particle size (∼300 nm) was synthesized through a facile coassembly of diblock polymer micelles with a nontoxic dopamine source and a common postactivation process. The mesopore size can be controlled by the diblock polymer, polystyrene-block-poly(ethylene oxide) (PS-b-PEO) templates, and has an almost linear dependence on the square root of the degree of polymerization of the PS blocks. These advantageous structural properties make the product a promising electrode material for electrochemical capacitors. The electrochemical capacitive performance was studied carefully by using symmetrical cells in a typical organic electrolyte of 1 M tetraethylammonium tetrafluoroborate/acetonitrile (TEA BF 4 /AN) or in an ionic liquid electrolyte of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF 4 ), displaying a high specific capacitance of 111 and 170 F g -1 at 1 A g -1 , respectively. The impacts of pore size distribution on the capacitance performance were thoroughly investigated. It was revealed that large mesopores and a relatively low ratio of micropores are ideal for realizing high SSA-normalized capacitance. These results provide us with a simple and reliable way to screen future porous carbon materials for electrochemical capacitors and encourage researchers to design porous carbon with high specific surface area, large mesopores, and a moderate proportion of micropores.

Recent Advances in the Inverted Planar Structure of Perovskite Solar Cells.

PubMed

Meng, Lei; You, Jingbi; Guo, Tzung-Fang; Yang, Yang

2016-01-19

Inorganic-organic hybrid perovskite solar cells research could be traced back to 2009, and initially showed 3.8% efficiency. After 6 years of efforts, the efficiency has been pushed to 20.1%. The pace of development was much faster than that of any type of solar cell technology. In addition to high efficiency, the device fabrication is a low-cost solution process. Due to these advantages, a large number of scientists have been immersed into this promising area. In the past 6 years, much of the research on perovskite solar cells has been focused on planar and mesoporous device structures employing an n-type TiO2 layer as the bottom electron transport layer. These architectures have achieved champion device efficiencies. However, they still possess unwanted features. Mesoporous structures require a high temperature (>450 °C) sintering process for the TiO2 scaffold, which will increase the cost and also not be compatible with flexible substrates. While the planar structures based on TiO2 (regular structure) usually suffer from a large degree of J-V hysteresis. Recently, another emerging structure, referred to as an "inverted" planar device structure (i.e., p-i-n), uses p-type and n-type materials as bottom and top charge transport layers, respectively. This structure derived from organic solar cells, and the charge transport layers used in organic photovoltaics were successfully transferred into perovskite solar cells. The p-i-n structure of perovskite solar cells has shown efficiencies as high as 18%, lower temperature processing, flexibility, and, furthermore, negligible J-V hysteresis effects. In this Account, we will provide a comprehensive comparison of the mesoporous and planar structures, and also the regular and inverted of planar structures. Later, we will focus the discussion on the development of the inverted planar structure of perovskite solar cells, including film growth, band alignment, stability, and hysteresis. In the film growth part, several methods for obtaining high quality perovskite films are reviewed. In the interface engineering parts, the effect of hole transport layer on subsequent perovskite film growth and their interface band alignment, and also the effect of electron transport layers on charge transport and interface contact will be discussed. As concerns stability, the role of charge transport layers especially the top electron transport layer in the devices stability will be concluded. In the hysteresis part, possible reasons for hysteresis free in inverted planar structure are provided. At the end of this Account, future development and possible solutions to the remaining challenges facing the commercialization of perovskite solar cells are discussed.

Mesoporous nickel oxide nanowires: hydrothermal synthesis, characterisation and applications for lithium-ion batteries and supercapacitors with superior performance.

PubMed

Su, Dawei; Kim, Hyun-Soo; Kim, Woo-Seong; Wang, Guoxiu

2012-06-25

Mesoporous nickel oxide nanowires were synthesized by a hydrothermal reaction and subsequent annealing at 400 °C. The porous one-dimensional nanostructures were analysed by field-emission SEM, high-resolution TEM and N(2) adsorption/desorption isotherm measurements. When applied as the anode material in lithium-ion batteries, the as-prepared mesoporous nickel oxide nanowires demonstrated outstanding electrochemical performance with high lithium storage capacity, satisfactory cyclability and an excellent rate capacity. They also exhibited a high specific capacitance of 348 F g(-1) as electrodes in supercapacitors. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of novel thiol-functionalized mesoporous silica nanorods and their sorbent properties on heavy metals

NASA Astrophysics Data System (ADS)

Chen, Xi; Cai, Qiang; Sun, Lin-Hao; Zhang, Wei; Jiang, Xing-Yu

2012-09-01

Novel thiol-functionalized mesoporous silica nanorods (MSNRs) were synthesized through a base co-condensation method, in which two organoalkoxysilanes, tetraethoxylsilane (TEOS) and bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT), were used as silica precursors simultaneously. TESPT was firstly used for both morphology control and inner surface functionalization of mesoporous silica hybrid materials. The microstructures as well as porous character of the MSNRs were characterized by means of SEM, XRD, TEM and N2 sorption measurements. Infrared spectrum analysis and heavy metal ions (Ag+ and Cd2+) adsorption measurements were carried out to confirm the functionalized framework of MSNRs.

Templated assembly of BiFeO3 nanocrystals into 3D mesoporous networks for catalytic applications

NASA Astrophysics Data System (ADS)

Papadas, I. T.; Subrahmanyam, K. S.; Kanatzidis, M. G.; Armatas, G. S.

2015-03-01

The self-assembly of uniform nanocrystals into large porous architectures is currently of immense interest for nanochemistry and nanotechnology. These materials combine the respective advantages of discrete nanoparticles and mesoporous structures. In this article, we demonstrate a facile nanoparticle templating process to synthesize a three-dimensional mesoporous BiFeO3 material. This approach involves the polymer-assisted aggregating assembly of 3-aminopropanoic acid-stabilized bismuth ferrite (BiFeO3) nanocrystals followed by thermal decomposition of the surfactant. The resulting material consists of a network of tightly connected BiFeO3 nanoparticles (~6-7 nm in diameter) and has a moderately high surface area (62 m2 g-1) and uniform pores (ca. 6.3 nm). As a result of the unique mesostructure, the porous assemblies of BiFeO3 nanoparticles show an excellent catalytic activity and chemical stability for the reduction of p-nitrophenol to p-aminophenol with NaBH4.The self-assembly of uniform nanocrystals into large porous architectures is currently of immense interest for nanochemistry and nanotechnology. These materials combine the respective advantages of discrete nanoparticles and mesoporous structures. In this article, we demonstrate a facile nanoparticle templating process to synthesize a three-dimensional mesoporous BiFeO3 material. This approach involves the polymer-assisted aggregating assembly of 3-aminopropanoic acid-stabilized bismuth ferrite (BiFeO3) nanocrystals followed by thermal decomposition of the surfactant. The resulting material consists of a network of tightly connected BiFeO3 nanoparticles (~6-7 nm in diameter) and has a moderately high surface area (62 m2 g-1) and uniform pores (ca. 6.3 nm). As a result of the unique mesostructure, the porous assemblies of BiFeO3 nanoparticles show an excellent catalytic activity and chemical stability for the reduction of p-nitrophenol to p-aminophenol with NaBH4. Electronic supplementary information (ESI) available: IR spectra and TG profiles of as-made BiFeO3 NPs and MBFA samples, TEM images of 3-APA-capped BiFeO3 NPs, EDS spectrum of MBFAs, N2 adsorption-desorption isotherms of randomly aggregated BiFeO3 NPs and catalytic data for 4-NP reduction by MBFAs and other nanostructured catalysts. See DOI: 10.1039/c5nr00185d

Stabilization of RNA through Absorption by Functionalized Mesoporous Silicate Nanospheres

DTIC Science & Technology

2012-11-30

storage or storage in restrictive environments. Materials and Methods Chemicals Bovine serum albumin (BSA), trehalose , glucosamine, tetraethyl...NS) were functionalized with trehalose (NS- T), glucosamine (NS-G), and BSA (NS-B). Functionalization of sorbents resulted in a loss in surface area...92 Å for glucosamine and trehalose functionalization (Fig. 2B). BSA functionalization resulted in an apparent loss in smaller diameter mesopores. The

General method for the synthesis of hierarchical nanocrystal-based mesoporous materials.

PubMed

Rauda, Iris E; Buonsanti, Raffaella; Saldarriaga-Lopez, Laura C; Benjauthrit, Kanokraj; Schelhas, Laura T; Stefik, Morgan; Augustyn, Veronica; Ko, Jesse; Dunn, Bruce; Wiesner, Ulrich; Milliron, Delia J; Tolbert, Sarah H

2012-07-24

Block copolymer templating of inorganic materials is a robust method for the production of nanoporous materials. The method is limited, however, by the fact that the molecular inorganic precursors commonly used generally form amorphous porous materials that often cannot be crystallized with retention of porosity. To overcome this issue, here we present a general method for the production of templated mesoporous materials from preformed nanocrystal building blocks. The work takes advantage of recent synthetic advances that allow organic ligands to be stripped off of the surface of nanocrystals to produce soluble, charge-stabilized colloids. Nanocrystals then undergo evaporation-induced co-assembly with amphiphilic diblock copolymers to form a nanostructured inorganic/organic composite. Thermal degradation of the polymer template results in nanocrystal-based mesoporous materials. Here, we show that this method can be applied to nanocrystals with a broad range of compositions and sizes, and that assembly of nanocrystals can be carried out using a broad family of polymer templates. The resultant materials show disordered but homogeneous mesoporosity that can be tuned through the choice of template. The materials also show significant microporosity, formed by the agglomerated nanocrystals, and this porosity can be tuned by the nanocrystal size. We demonstrate through careful selection of the synthetic components that specifically designed nanostructured materials can be constructed. Because of the combination of open and interconnected porosity, high surface area, and compositional tunability, these materials are likely to find uses in a broad range of applications. For example, enhanced charge storage kinetics in nanoporous Mn(3)O(4) is demonstrated here.

Method for rapidly producing microporous and mesoporous materials

DOEpatents

Coronado, Paul R.; Poco, John F.; Hrubesh, Lawrence W.; Hopper, Robert W.

1997-01-01

An improved, rapid process is provided for making microporous and mesoporous materials, including aerogels and pre-ceramics. A gel or gel precursor is confined in a sealed vessel to prevent structural expansion of the gel during the heating process. This confinement allows the gelation and drying processes to be greatly accelerated, and significantly reduces the time required to produce a dried aerogel compared to conventional methods. Drying may be performed either by subcritical drying with a pressurized fluid to expel the liquid from the gel pores or by supercritical drying. The rates of heating and decompression are significantly higher than for conventional methods.

Superior lithium electroactive mesoporous Si@carbon core-shell nanowires for lithium battery anode material.

PubMed

Kim, Hyesun; Cho, Jaephil

2008-11-01

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.

Nanocrystalline heterojunction materials

DOEpatents

Elder, Scott H.; Su, Yali; Gao, Yufei; Heald, Steve M.

2003-07-15

Mesoporous nanocrystalline titanium dioxide heterojunction materials are disclosed. In one disclosed embodiment, materials comprising a core of titanium dioxide and a shell of a molybdenum oxide exhibit a decrease in their photoadsorption energy as the size of the titanium dioxide core decreases.

Mesoporous aluminosilicate glasses: Potential materials for dye removal from wastewater effluents

NASA Astrophysics Data System (ADS)

Almeida, Flavio P.; Botelho, Moema B. S.; Doerenkamp, Carsten; Kessler, Elizaveta; Ferrari, Cynthia R.; Eckert, Hellmut; de Camargo, Andrea S. S.

2017-09-01

Mesoporous amorphous sodium-aluminosilicate host matrices of composition Si1-xAlxNaxO2, 0.1 ≤ x ≤ 0.33, obtained by sol-gel methodology, have been used as sequestrating agents for the cationic dye Rhodamine 6 G (Rh6G) in solution. Favorable adsorption kinetics and a wide pH working range (4-10) as well as high sorption capacities for Rh6G render these materials potentially useful reagents for effective dye removal from wastewaters. While the experimentally realized sorption capacities fall significantly below the theoretical limits, used materials can be thermally re-cycled by pyrolizing the sequestrated dye molecules. Solid state NMR and BET measurements show that this process occurs under preservation of the materials' structural integrity, allowing it to be re-used multiple times.

Monodisperse Mesoporous Carbon Nanoparticles from Polymer/Silica Self-Aggregates and Their Electrocatalytic Activities.

PubMed

Huang, Xiaoxi; Zhou, Li-Jing; Voiry, Damien; Chhowalla, Manish; Zou, Xiaoxin; Asefa, Tewodros

2016-07-27

In our quest to make various chemical processes sustainable, the development of facile synthetic routes and inexpensive catalysts can play a central role. Herein we report the synthesis of monodisperse, polyaniline (PANI)-derived mesoporous carbon nanoparticles (PAMCs) that can serve as efficient metal-free electrocatalysts for the hydrogen peroxide reduction reaction (HPRR) as well as the oxygen reduction reaction (ORR) in fuel cells. The materials are synthesized by polymerization of aniline with the aid of (NH4)2S2O8 as oxidant and colloidal silica nanoparticles as templates, then carbonization of the resulting PANI/silica composite material at different high temperatures, and finally removal of the silica templates from the carbonized products. The PAMC materials that are synthesized under optimized synthetic conditions possess monodisperse mesoporous carbon nanoparticles with an average size of 128 ± 12 nm and an average pore size of ca. 12 nm. Compared with Co3O4, a commonly used electrocatalyst for HPRR, these materials show much better catalytic activity for this reaction. In addition, unlike Co3O4, the PAMCs remain relatively stable during the reaction, under both basic and acidic conditions. The nanoparticles also show good electrocatalytic activity toward ORR. Based on the experimental results, PAMCs' excellent electrocatalytic activity is attributed partly to their heteroatom dopants and/or intrinsic defect sites created by vacancies in their structures and partly to their high porosity and surface area. The reported synthetic method is equally applicable to other polymeric precursors (e.g., polypyrrole (PPY)), which also produces monodisperse, mesoporous carbon nanoparticles in the same way. The resulting materials are potentially useful not only for electrocatalysis of HPRR and ORR in fuel cells but also for other applications where high surface area, small sized, nanostructured carbon materials are generally useful for (e.g., adsorption, supercapacitors, etc.).

Synthesis and characterization of different MnO2 morphologies for lithium-air batteries

NASA Astrophysics Data System (ADS)

Choi, Hyun-A.; Jang, Hyuk; Hwang, Hyein; Choi, Mincheol; Lim, Dongwook; Shim, Sang Eun; Baeck, Sung-Hyeon

2014-09-01

Manganese dioxide (MnO2) was synthesized in the forms of nanorods, nanoparticles, and mesoporous structures and the characteristics of these materials were investigated. Crystallinities were studied by x-ray diffraction and morphologies by scanning and transmission electron microscopy. Average pore sizes and specific surface areas were analyzed using the Barret-Joyner-Halenda and Brunauer-Emmett-Teller methods, respectively. Samples were also studied by cyclic voltammetry using 1M aqueous KOH solution saturated with either O2 or N2 as electrolytes to investigate their ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) activities. Of the samples produced, mesoporous MnO2 exhibited the highest ORR and OER catalytic activities. Mesoporous MnO2 supported on a gas diffusion layer was also used as a catalyst on the air electrode (cathode) of a lithium-air battery in organic electrolyte. The charge-discharge behavior of mesoporous MnO2 was investigated at a current density 0.2 mAcm-2 in a pure oxygen environment. Mesoporous MnO2 electrodes showed stable cycleability up to 65 cycles at a cell capacity of 700 mAhg-1.

Hierarchical activated mesoporous phenolic-resin-based carbons for supercapacitors.

PubMed

Wang, Zhao; Zhou, Min; Chen, Hao; Jiang, Jingui; Guan, Shiyou

2014-10-01

A series of hierarchical activated mesoporous carbons (AMCs) were prepared by the activation of highly ordered, body-centered cubic mesoporous phenolic-resin-based carbon with KOH. The effect of the KOH/carbon-weight ratio on the textural properties and capacitive performance of the AMCs was investigated in detail. An AMC prepared with a KOH/carbon-weight ratio of 6:1 possessed the largest specific surface area (1118 m(2) g(-1)), with retention of the ordered mesoporous structure, and exhibited the highest specific capacitance of 260 F g(-1) at a current density of 0.1 A g(-1) in 1 M H2 SO4 aqueous electrolyte. This material also showed excellent rate capability (163 F g(-1) retained at 20 A g(-1)) and good long-term electrochemical stability. This superior capacitive performance could be attributed to a large specific surface area and an optimized micro-mesopore structure, which not only increased the effective specific surface area for charge storage but also provided a favorable pathway for efficient ion transport. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mesoporous g-C₃N₄ Nanosheets: Synthesis, Superior Adsorption Capacity and Photocatalytic Activity.

PubMed

Li, Dong-Feng; Huang, Wei-Qing; Zou, Lan-Rong; Pan, Anlian; Huang, Gui-Fang

2018-08-01

Elimination of pollutants from water is one of the greatest challenges in resolving global environmental issues. Herein, we report a high-surface-area mesoporous g-C3N4 nanosheet with remarkable high adsorption capacity and photocatalytic performance, which is prepared through directly polycondensation of urea followed by a consecutive one-step thermal exfoliation strategy. This one-pot method to prepare mesoporous g-C3N4 nanosheet is facile and rapid in comparison with others. The superior adsorption capacity of the fabricated mesoporous g-C3N4 nanostructures is demonstrated by a model organic pollutant-methylene blue (MB), which is up to 72.2 mg/g, about 6 times as that of the largest value of various g-C3N4 adsorbents reported so far. Moreover, this kind of porous g-C3N4 nanosheet exhibits high photocatalytic activity to MB and phenol degradation. Particularly, the regenerated samples show excellent performance of pollutant removal after consecutive adsorption/degradation cycles. Therefore, this mesoporous g-C3N4 nanosheet may be an attractive robust metal-free material with great promise for organic pollutant elimination.

Facile Control of the Porous Structure of Larch-Derived Mesoporous Carbons via Self-Assembly for Supercapacitors

PubMed Central

Zhao, Xin; Li, Wei; Chen, Honglei; Wang, Shoujuan; Kong, Fangong; Liu, Shouxin

2017-01-01

Mesoporous carbons have been successfully synthesized via self-assembly using larch-based resins as precursors and triblock copolymers as soft templates. The porous structure of mesoporous carbons can be tailored by adjusting the ratio of hydrophilic/hydrophobic (EO/PO) units owing to interfacial curvature. Interestingly, the porous structures show a distinct change from vortex-like to worm-like pores, to stripe-like pores, and to ordered two-dimensional hexagonal pores as the ratio of hydrophilic/hydrophobic units increases, indicating the significant effect of EO/PO ratio on the porous structure. The mesoporous carbons as supercapacitor electrodes exhibit superior electrochemical capacitive performance and a high degree of reversibility after 2000 cycles for supercapacitors due to the well-defined mesoporosity of the carbon materials. Meanwhile, the superior carbon has a high specific capacitance of 107 F·g−1 in 6 M KOH at a current density of 10 A·g−1. PMID:29156641

Facile Control of the Porous Structure of Larch-Derived Mesoporous Carbons via Self-Assembly for Supercapacitors.

PubMed

Zhao, Xin; Li, Wei; Chen, Honglei; Wang, Shoujuan; Kong, Fangong; Liu, Shouxin

2017-11-20

Mesoporous carbons have been successfully synthesized via self-assembly using larch-based resins as precursors and triblock copolymers as soft templates. The porous structure of mesoporous carbons can be tailored by adjusting the ratio of hydrophilic/hydrophobic (EO/PO) units owing to interfacial curvature. Interestingly, the porous structures show a distinct change from vortex-like to worm-like pores, to stripe-like pores, and to ordered two-dimensional hexagonal pores as the ratio of hydrophilic/hydrophobic units increases, indicating the significant effect of EO/PO ratio on the porous structure. The mesoporous carbons as supercapacitor electrodes exhibit superior electrochemical capacitive performance and a high degree of reversibility after 2000 cycles for supercapacitors due to the well-defined mesoporosity of the carbon materials. Meanwhile, the superior carbon has a high specific capacitance of 107 F·g -1 in 6 M KOH at a current density of 10 A·g -1 .

Low-temperature direct synthesis of mesoporous vanadium nitrides for electrochemical capacitors

NASA Astrophysics Data System (ADS)

Lee, Hae-Min; Jeong, Gyoung Hwa; Kim, Sang-Wook; Kim, Chang-Koo

2017-04-01

Mesoporous vanadium nitrides are directly synthesized by a one-step chemical precipitation method at a low temperature (70 °C). Structural and morphological analyses reveal that vanadium nitride consist of long and slender nanowhiskers, and mesopores with diameters of 2-5 nm. Compositional analysis confirms the presence of vanadium in the VN structure, along with oxidized vanadium. The cyclic voltammetry and charge-discharge tests indicate that the obtained material stores charges via a combination of electric double-layer capacitance and pseudocapacitance mechanisms. The vanadium nitride electrode exhibits a specific capacitance of 598 F/g at a current density of 4 A/g. After 5000 charge-discharge cycles, the electrode has an equivalent series resistance of 1.42 Ω and retains 83% of its initial specific capacitance. This direct low-temperature synthesis of mesoporous vanadium nitrides is a simple and promising method to achieve high specific capacitance and low equivalent series resistance for electrochemical capacitor applications.

Atomically Thin Mesoporous Nanomesh of Graphitic C₃N₄ for High-Efficiency Photocatalytic Hydrogen Evolution.

PubMed

Han, Qing; Wang, Bing; Gao, Jian; Cheng, Zhihua; Zhao, Yang; Zhang, Zhipan; Qu, Liangti

2016-02-23

Delamination of layer materials into two-dimensional single-atom sheets has induced exceptional physical properties, including large surface area, ultrahigh intrinsic carrier mobility, pronounced changes in the energy band structure, and other properties. Here, atomically thin mesoporous nanomesh of graphitic carbon nitride (g-C3N4) is fabricated by solvothermal exfoliation of mesoporous g-C3N4 bulk made from thermal polymerization of freeze-drying assembled Dicyandiamide nanostructure precursor. With the unique structural advantages for aligned energy levels, electron transfer, light harvesting, and the richly available reaction sites, the as-prepared monolayer of mesoporous g-C3N4 nanomesh exhibits a superior photocatalytic hydrogen evolution rate of 8510 μmol h(-1) g(-1) under λ > 420 nm and an apparent quantum efficiency of 5.1% at 420 nm, the highest of all the metal-free g-C3N4 nanosheets photocatalysts.

Templated synthesis of highly ordered mesoporous cobalt ferrite and its microwave absorption properties

NASA Astrophysics Data System (ADS)

Li, Guo-Min; Wang, Lian-Cheng; Xu, Yao

2014-08-01

Based on the nanocasting strategy, highly ordered mesoporous CoFe2O4 is synthesized via the ‘two-solvent’ impregnation method using a mesoporous SBA-15 template. An ordered two-dimensional (P6mm) structure is preserved for the CoFe2O4/SBA-15 composite after the nanocasting. After the SBA-15 template is dissolved by NaOH solution, a mesoporous structure composed of aligned nanoparticles can be obtained, and the P6mm structure of the parent SBA-15 is preserved. With a high specific surface area (above 90 m2/g) and ferromagnetic behavior, the obtained material shows potential in light weight microwave absorption application. The minimum reflection loss (RL) can reach -18 dB at about 16 GHz with a thickness of 2 mm and the corresponding absorption bandwidth is 4.5 GHz.

Mesoporous Ge/GeO2/Carbon Lithium-Ion Battery Anodes with High Capacity and High Reversibility.

PubMed

Hwang, Jongkook; Jo, Changshin; Kim, Min Gyu; Chun, Jinyoung; Lim, Eunho; Kim, Seongseop; Jeong, Sanha; Kim, Youngsik; Lee, Jinwoo

2015-05-26

We report mesoporous composite materials (m-GeO2, m-GeO2/C, and m-Ge-GeO2/C) with large pore size which are synthesized by a simple block copolymer directed self-assembly. m-Ge/GeO2/C shows greatly enhanced Coulombic efficiency, high reversible capacity (1631 mA h g(-1)), and stable cycle life compared with the other mesoporous and bulk GeO2 electrodes. m-Ge/GeO2/C exhibits one of the highest areal capacities (1.65 mA h cm(-2)) among previously reported Ge- and GeO2-based anodes. The superior electrochemical performance in m-Ge/GeO2/C arises from the highly improved kinetics of conversion reaction due to the synergistic effects of the mesoporous structures and the conductive carbon and metallic Ge.

Effect of SiO2/Al2O3 Ratio on Micro-Mesopore Formation for Pt/Beta-MCM-41 via NaOH Treatment and the Catalytic Performance in N-heptane Hydro isomerization

NASA Astrophysics Data System (ADS)

Gao, Li; Shi, Zhiyuan; Liu, Yingming; Zhao, Yuanshou; Liu, Qinghua; Xu, Chengguo; Bai, Peng; Yan, Zifeng

2018-01-01

Micro-mesoporous composite material Beta-MCM-41(BM) were hydrothermally synthesized by treating parent beta with molar SiO2/Al2O3 ratios of 12.5, 20 and 30 as precursors. The influence of SiO2/Al2O3 ratio of zeolite beta on effective micro-mesoporous composite formation was studied by investigating the crystallinity, morphology, chemical composition, acidity and textural property of Beta-MCM-41 through XRD, nitrogen adsorption, SEM, TEM, NH3-TPD, FTIR and Pyridine-FTIR. The catalytic performance was evaluated in terms of n-heptane hydro isomerization. The results demonstrated that Beta-MCM-41 supported Pt catalysts showed higher selectivity to isoheptanes than Pt/Beta. It was attributed to the superiorities of the pore structure and mesoporous accelerated the diffusion of larger molecules of isoheptanes.

Facile synthesis of mesoporous spinel NiCo2O4 nanostructures as highly efficient electrocatalysts for urea electro-oxidation

NASA Astrophysics Data System (ADS)

Ding, Rui; Qi, Li; Jia, Mingjun; Wang, Hongyu

2014-01-01

Mesoporous spinel nickel cobaltite (NiCo2O4) nanostructures were synthesized via a facile chemical deposition method coupled with a simple post-annealing process. The physicochemical properties were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. The electrocatalytic performances were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained NiCo2O4 materials exhibit typical agglomerate mesoporous nanostructures with a large surface area (190.1 m2 g-1) and high mesopore volume (0.943 cm3 g-1). Remarkably, the NiCo2O4 shows much higher catalytic activity, lower overpotential, better stability and greater tolerance towards urea electro-oxidation compared to those of cobalt oxide (Co3O4) synthesized by the same procedure. The NiCo2O4 electrode delivers a current density of 136 mA cm-2 mg-1 at 0.7 V (vs. Hg/HgO) in 1 M KOH and 0.33 M urea electrolytes accompanied with a desirable stability. The impressive electrocatalytic activity is largely ascribed to the high intrinsic electronic conductivity, superior mesoporous nanostructures and rich surface Ni active species of the NiCo2O4 materials, which can largely boost the interfacial electroactive sites and charge transfer rates for urea electro-oxidation, indicating promising applications in future wastewater remediation, hydrogen production and fuel cells.Mesoporous spinel nickel cobaltite (NiCo2O4) nanostructures were synthesized via a facile chemical deposition method coupled with a simple post-annealing process. The physicochemical properties were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. The electrocatalytic performances were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained NiCo2O4 materials exhibit typical agglomerate mesoporous nanostructures with a large surface area (190.1 m2 g-1) and high mesopore volume (0.943 cm3 g-1). Remarkably, the NiCo2O4 shows much higher catalytic activity, lower overpotential, better stability and greater tolerance towards urea electro-oxidation compared to those of cobalt oxide (Co3O4) synthesized by the same procedure. The NiCo2O4 electrode delivers a current density of 136 mA cm-2 mg-1 at 0.7 V (vs. Hg/HgO) in 1 M KOH and 0.33 M urea electrolytes accompanied with a desirable stability. The impressive electrocatalytic activity is largely ascribed to the high intrinsic electronic conductivity, superior mesoporous nanostructures and rich surface Ni active species of the NiCo2O4 materials, which can largely boost the interfacial electroactive sites and charge transfer rates for urea electro-oxidation, indicating promising applications in future wastewater remediation, hydrogen production and fuel cells. Electronic supplementary information (ESI) available: XRD patterns of NO and CO; XRD patterns and XPS profiles of CO; SEM images of CO; BET plots of CO; XPS quantitative analysis of NCO; a comparison of N2 sorption data between NCO and CO; the fitted values of impedimetric parameters of NCO and CO electrodes. See DOI: 10.1039/c3nr05359h

Mesoporous inorganic salts with crystal defects: unusual catalysts and catalyst supports† †Electronic supplementary information (ESI) available: Scheme S1 contains reaction equation, Fig. S1–S7 contain solubility test, XRD, SEM, TEM, micropore size distribution and reaction conversion. See DOI: 10.1039/c4sc03736g Click here for additional data file.

PubMed Central

Kang, Xinchen; Shang, Wenting; Zhu, Qinggong; Zhang, Jianling; Wu, Zhonghua; Li, Zhihong; Xing, Xueqing

2015-01-01

We proposed a strategy to synthesize mesoporous inorganic salt particles using the special properties of ionic liquid (IL) mixtures, and hollow mesoporous LaF3, NdF3, and YF3 particles were synthesized and characterized using different techniques. The size of the mesopores in the salt particles was about 4 nm, and the materials were full of crystal defects. The LaF3, NdF3 and YF3 particles were used as the catalysts for the cyanosilylation reaction of benzaldehyde using trimethylsilyl cyanide, and Ru/LaF3 and Ru/NdF3, in which Ru nanocatalysts were supported on the LaF3 and NdF3 particles with mesopores, were used to catalyze hydrogenations of benzene to cyclohexane and levulinic acid (LA) to γ-valerolactone (GVL). It was discovered that the activities of these catalysts were unprecedentedly high for these reactions. Detailed study showed that both the crystal defects and the mesopores in the salt particles played crucial roles for the extremely high catalytic activity. PMID:29308132

Fabrication of mesoporous metal oxide coated-nanocarbon hybrid materials via a polyol-mediated self-assembly process

NASA Astrophysics Data System (ADS)

Feng, Bingmei; Wang, Huixin; Wang, Dongniu; Yu, Huilong; Chu, Yi; Fang, Hai-Tao

2014-11-01

After clarifying the formation mechanism of a typical metal glycolate precipitate, Ti glycolate, in a polyol-mediated synthesis using acetone as a precipitation medium, we describe a simple template-free approach based on an ethylene glycol-mediated synthesis to fabricate mesoporous metal oxide coated-nanocarbon hybrid materials including TiO2 coated-carbon nanotube (CNT), SnO2 coated-CNT, Cu2O/CuO coated-CNT and TiO2 coated-graphene sheet (GS). In the approach, metal oxide precursors, metal glycolates, were first deposited on CNTs or GSs, and subsequently transformed to the metal oxide coatings by pyrolysis or hydrolysis. By a comparison between the characterization of two TiO2-CNT hybrid materials using carboxylated CNTs and pristine CNTs without carboxyl groups, the driving force for initiating the deposition of metal glycolates on the carboxylated CNTs is confirmed to be the hydrogen bonding between the carboxyl groups and the polymer chains in metal glycolate sols. The electrochemical performances of the mesoporous TiO2 coated-carboxylated CNTs and TiO2-pristine CNT hybrid materials were investigated. The results show that the mesoporous TiO2 coated-carboxylated CNT with a uniform core-shell nanostructure exhibits substantial improvement in the rate performance in comparison with its counterpart from 0.5 C to 100 C because of its higher electronic conductivity and shorter diffusion path for the lithium ion. At the extremely high rate of 100 C, the specific capacity of TiO2 of the former reaches 85 mA h g-1, twice as high as that of the latter.After clarifying the formation mechanism of a typical metal glycolate precipitate, Ti glycolate, in a polyol-mediated synthesis using acetone as a precipitation medium, we describe a simple template-free approach based on an ethylene glycol-mediated synthesis to fabricate mesoporous metal oxide coated-nanocarbon hybrid materials including TiO2 coated-carbon nanotube (CNT), SnO2 coated-CNT, Cu2O/CuO coated-CNT and TiO2 coated-graphene sheet (GS). In the approach, metal oxide precursors, metal glycolates, were first deposited on CNTs or GSs, and subsequently transformed to the metal oxide coatings by pyrolysis or hydrolysis. By a comparison between the characterization of two TiO2-CNT hybrid materials using carboxylated CNTs and pristine CNTs without carboxyl groups, the driving force for initiating the deposition of metal glycolates on the carboxylated CNTs is confirmed to be the hydrogen bonding between the carboxyl groups and the polymer chains in metal glycolate sols. The electrochemical performances of the mesoporous TiO2 coated-carboxylated CNTs and TiO2-pristine CNT hybrid materials were investigated. The results show that the mesoporous TiO2 coated-carboxylated CNT with a uniform core-shell nanostructure exhibits substantial improvement in the rate performance in comparison with its counterpart from 0.5 C to 100 C because of its higher electronic conductivity and shorter diffusion path for the lithium ion. At the extremely high rate of 100 C, the specific capacity of TiO2 of the former reaches 85 mA h g-1, twice as high as that of the latter. Electronic supplementary information (ESI) available. See DOI: 10.1039/C4NR04254A

Fine-tuning the release of molecular guests from mesoporous silicas by controlling the orientation and mobility of surface phenyl substituents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manzano, J. Sebastian; Singappuli-Arachchige, Dilini; Parikh, Bosky L.

Phenyl-functionalized mesoporous silica materials were used to explore the effect of non-covalent interactions on the release of Ibuprofen into simulated body fluid. Variations in orientation and conformational mobility of the surface phenyl groups were introduced by selecting different structural precursors: a rigid upright orientation was obtained using phenyl groups directly bound to surface Si atoms (Ph-MSN), mobile groups were produced by using ethylene linkers to connect phenyl groups to the surface (PhEt-MSN), and groups co-planar to the surface were obtained by synthesizing a phenylene-bridged periodic mesoporous organosilica (Ph-PMO). The Ibuprofen release profiles from these materials and non-functionalized mesoporous silica nanoparticlesmore » (MSN) were analyzed using an adsorption-diffusion model. The model provided kinetic and thermodynamic parameters that evidenced fundamental differences in drug-surface interactions between the materials. All phenyl-bearing materials show lower Ibuprofen initial release rates than bare MSN. The conformationally locked Ph-MSN and Ph-PMO have stronger interactions with the drug (negative ΔG of adsorption) than the flexible PhEt-MSN and bare MSN (positive ΔG of adsorption). These differences in strength of adsorption are consistent with differences between interaction geometries obtained from DFT calculations. B3LYP-D3-optimized models show that π-π interactions contribute more to drug adsorption than H-bonding with silanol groups. Here, the results suggest that the type and geometry of interactions control the kinetics and extent of drug release, and should therefore serve as a guide to design new drug delivery systems with precise release behaviors customized to any desired target.« less

Fine-tuning the release of molecular guests from mesoporous silicas by controlling the orientation and mobility of surface phenyl substituents

DOE PAGES

Manzano, J. Sebastian; Singappuli-Arachchige, Dilini; Parikh, Bosky L.; ...

2017-12-05

Phenyl-functionalized mesoporous silica materials were used to explore the effect of non-covalent interactions on the release of Ibuprofen into simulated body fluid. Variations in orientation and conformational mobility of the surface phenyl groups were introduced by selecting different structural precursors: a rigid upright orientation was obtained using phenyl groups directly bound to surface Si atoms (Ph-MSN), mobile groups were produced by using ethylene linkers to connect phenyl groups to the surface (PhEt-MSN), and groups co-planar to the surface were obtained by synthesizing a phenylene-bridged periodic mesoporous organosilica (Ph-PMO). The Ibuprofen release profiles from these materials and non-functionalized mesoporous silica nanoparticlesmore » (MSN) were analyzed using an adsorption-diffusion model. The model provided kinetic and thermodynamic parameters that evidenced fundamental differences in drug-surface interactions between the materials. All phenyl-bearing materials show lower Ibuprofen initial release rates than bare MSN. The conformationally locked Ph-MSN and Ph-PMO have stronger interactions with the drug (negative ΔG of adsorption) than the flexible PhEt-MSN and bare MSN (positive ΔG of adsorption). These differences in strength of adsorption are consistent with differences between interaction geometries obtained from DFT calculations. B3LYP-D3-optimized models show that π-π interactions contribute more to drug adsorption than H-bonding with silanol groups. Here, the results suggest that the type and geometry of interactions control the kinetics and extent of drug release, and should therefore serve as a guide to design new drug delivery systems with precise release behaviors customized to any desired target.« less

MoO2-ordered mesoporous carbon hybrids as anode materials with highly improved rate capability and reversible capacity for lithium-ion battery.

PubMed

Chen, Ailian; Li, Caixia; Tang, Rui; Yin, Longwei; Qi, Yongxin

2013-08-28

A novel hybrid of MoO2-ordered mesoporous carbon (MoO2-OMC) was prepared through a two-step solvothermal chemical reaction route. The electrochemical performances of the mesoporous MoO2-OMC hybrids were examined using galvanostatical charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) techniques. The MoO2-OMC hybrid exhibits significantly improved electrochemical performance of high reversible capacity, high-rate capability, and excellent cycling performance as an anode electrode material for Li ion batteries. It is revealed that the MoO2-OMC hybrid could deliver the first discharge capacity of 1641.8 mA h g(-1) with an initial Coulombic efficiency of 63.6%, and a reversible capacity as high as 1049.1 mA h g(-1) even after 50 cycles at a current density of 100 mA g(-1), much higher than the theoretical capacity of MoO2 (838 mA h g(-1)) and OMC materials. The MoO2-OMC hybrid demonstrates an excellent high rate capability with capacity of ∼600 mA h g(-1) even at a charge current density of 1600 mA g(-1) after 50 cycles, which is approximately 11.1 times higher than that of the OMC (54 mA h g(-1)) materials. The improved rate capability and reversible capacity of the MoO2-OMC hybrid are attributed to a synergistic reaction between the MoO2 nanoparticles and mesoporous OMC matrices. It is noted that the electrochemical performance of the MoO2-OMC hybrid is evidently much better than the previous MoO2-based hybrids.

Facile and green synthesis of mesoporous Co3O4 nanocubes and their applications for supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Xiangmei; Long, Qing; Jiang, Chunhui; Zhan, Beibei; Li, Chen; Liu, Shujuan; Zhao, Qiang; Huang, Wei; Dong, Xiaochen

2013-06-01

Nanostructured Co3O4 materials attracted significant attention due to their exceptional electrochemical (pseudo-capacitive) properties. However, rigorous preparation conditions are needed to control the size (especially nanosize), morphology and size distribution of the products obtained by conventional methods. Herein, we describe a novel one step shape-controlled synthesis of uniform Co3O4 nanocubes with a size of 50 nm with the existence of mesoporous carbon nanorods (meso-CNRs). In this synthesis process, meso-CNRs not only act as a heat receiver to directly obtain Co3O4 eliminating the high-temperature post-calcination, but also control the morphology of the resulting Co3O4 to form nanocubes with uniform distribution. More strikingly, mesoporous Co3O4 nanocubes are obtained by further thermal treatment. The structure and morphology of the samples were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A possible formation mechanism of mesoporous Co3O4 nanocubes is proposed here. Electrochemical tests have revealed that the prepared mesoporous Co3O4 nanocubes demonstrate a remarkable performance in supercapacitor applications due to the porous structure, which endows fast ion and electron transfer.Nanostructured Co3O4 materials attracted significant attention due to their exceptional electrochemical (pseudo-capacitive) properties. However, rigorous preparation conditions are needed to control the size (especially nanosize), morphology and size distribution of the products obtained by conventional methods. Herein, we describe a novel one step shape-controlled synthesis of uniform Co3O4 nanocubes with a size of 50 nm with the existence of mesoporous carbon nanorods (meso-CNRs). In this synthesis process, meso-CNRs not only act as a heat receiver to directly obtain Co3O4 eliminating the high-temperature post-calcination, but also control the morphology of the resulting Co3O4 to form nanocubes with uniform distribution. More strikingly, mesoporous Co3O4 nanocubes are obtained by further thermal treatment. The structure and morphology of the samples were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A possible formation mechanism of mesoporous Co3O4 nanocubes is proposed here. Electrochemical tests have revealed that the prepared mesoporous Co3O4 nanocubes demonstrate a remarkable performance in supercapacitor applications due to the porous structure, which endows fast ion and electron transfer. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00495c

A mesoporous nickel counter electrode for printable and reusable perovskite solar cells.

PubMed

Ku, Zhiliang; Xia, Xinhui; Shen, He; Tiep, Nguyen Huy; Fan, Hong Jin

2015-08-28

A mesoporous nickel layer is used as the counter electrode in printable perovskite solar cells. A unique reuse process is realized in such perovskite solar cell devices by repeated loading of the perovskite material. Under standard AM1.5 illumination, the fresh device shows a promising power conversion efficiency of 13.6%, and an efficiency of 12.1% is obtained in the reused devices.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gencoglu, Maria F.; Spurri, Amanda; Franko, Mitchell

We report that soft-templated mesoporous carbon is morphologically a non-nano type of carbon. It is a relatively newer variety of biomaterial, which has already demonstrated its successful role in drug delivery applications. To investigate the toxicity and biocompatibility, we introduced three types of mesoporous carbons with varying synthesis conditions and pore textural properties. We compared the Brunauer–Emmett–Teller (BET) surface area and pore width and performed cytotoxicity experiments with HeLa cells, cell viability studies with fibroblast cells and hemocomapatibility studies. Cytotoxicity tests reveal that two of the carbons are not cytotoxic, with cell survival over 90%. The mesoporous carbon with themore » highest surface area showed slight toxicity (~70% cell survival) at the highest carbon concentration of 500 μg/mL. Fibroblast cell viability assays suggested high and constant viability of over 98% after 3 days with no apparent relation with materials property and good visible cell-carbon compatibility. No hemolysis (<1%) was confirmed for all the carbon materials. Protein adsorption experiments with bovine serum albumin (BSA) and fibrinogen revealed a lower protein binding capacity of 0.2–0.6 mg/m 2 and 2–4 mg/m 2 for BSA and fibrinogen, respectively, with lower binding associated with an increase in surface area. The results of this study confirm the biocompatibility of soft-templated mesoporous carbons.« less

Dissolution enhancement of a model poorly water-soluble drug, atorvastatin, with ordered mesoporous silica: comparison of MSF with SBA-15 as drug carriers.

PubMed

Maleki, Aziz; Hamidi, Mehrdad

2016-01-01

The purpose of this study was to develop mesoporous silica materials incorporated with poorly water-soluble drug atorvastatin calcium (AC) in order to improve drug dissolution, and intended to be orally administrated. A comparison between 2D-hexagonal silica nanostructured SBA-15 and mesocellular siliceous foam (MSF) with continuous 3D pore system on drug release rate was investigated. AC-loaded mesoporous silicas were characterized thorough N2 adsorption-desorption analysis, Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and dynamic light scattering (DLS). Results demonstrated a successful incorporation of AC into the silica-based hosts. The results taken from the drug release tests were also analyzed using different parameters, namely similarity factor (f2), difference factor (f1), dissolution efficiency (DE%), mean dissolution rate (MDR) and dissolution time (tm%). It confirmed a significant enhancement in the release profile of atorvastatin calcium with SBA-15, and MSF as drug carrier. Moreover, in comparison with SBA-15, MSF showed faster release rate of AC in enzyme-free simulated gastric fluid (pH 1.2). We believed that our findings can help the use of mesoporous silica materials in improving bioavailability of poorly water-soluble drugs.

Sulfur-infiltrated porous carbon microspheres with controllable multi-modal pore size distribution for high energy lithium-sulfur batteries.

PubMed

Zhao, Cunyu; Liu, Lianjun; Zhao, Huilei; Krall, Andy; Wen, Zhenhai; Chen, Junhong; Hurley, Patrick; Jiang, Junwei; Li, Ying

2014-01-21

Sulfur has received increasing attention as a cathode material for lithium-sulfur (Li-S) batteries due to its high theoretical specific capacity. However, the commercialization of Li-S batteries is limited by the challenges of poor electrical conductivity of sulfur, dissolution of the polysulfide intermediates into the electrolyte, and volume expansion of sulfur during cycling. Herein, we report the fabrication of novel-structured porous carbon microspheres with a controllable multi-modal pore size distribution, i.e., a combination of interconnected micropores, mesopores and macropores. Cathodes made of sulfur infiltrated in such a hierarchical carbon framework provide several advantages: (1) a continuous and high surface area carbon network for enhanced electrical conductivity and high sulfur loading; (2) macropores and large mesopores bridged by small mesopores to provide good electrolyte accessibility and fast Li ion transport and to accommodate volume expansion of sulfur; and (3) small mesopores and micropores to improve carbon/sulfur interaction and to help trap polysulfides. An initial discharge capacity at 1278 mA h g(-1) and capacity retention at 70.7% (904 mA h g(-1)) after 100 cycles at a high rate (1 C) were achieved. The material fabrication process is relatively simple and easily scalable.

Design and Synthesis of Self-Assembled Monolayers on Mesoporous Supports (SAMMS): The Importance of Ligand Posture in Functional Nanomaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fryxell, Glen E.; Mattigod, Shas V.; Lin, Yuehe

2007-07-01

Water, and water quality, are issues of critical importance to the future of humankind. The Earth’s water supplies have been contaminated by a wide variety of industrial, military and natural sources. The need exists for an efficient separation technology to remove heavy metal and radionuclide contamination from water. Surfactant templated synthesis of mesoporous ceramics provides a versatile foundation upon which to build high efficiency environmental sorbents. These nanoporous ceramics condense a huge amount of surface area into a very small volume. These mesoporous architectures can be subsequently functionalized through molecular self-assembly. These functional mesoporous materials offer significant capabilities in termsmore » of removal of heavy metals and radionuclides from a variety of liquid media, including groundwater, contaminated oils and contaminated chemical weapons. They are highly efficient sorbents, whose rigid, open pore structure allows for rapid, efficient sorption kinetics. Their interfacial chemistry can be fine-tuned to selectively sequester a specific target species, such as heavy metals, tetrahedral oxometallate anions and radionuclides. This manuscript provides a review of the design, synthesis and performance of the sorbent materials. The role that ligand posture plays in the chemistry of these interfacial ligand fields is discussed.« less

Adsorption of a Catalytically Accessible Polyoxometalate in a Mesoporous Channel-type Metal–Organic Framework

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buru, Cassandra T.; Li, Peng; Mehdi, B. Layla

2017-05-22

A Keggin-type polyoxometalate (H3PW12O40) was incorporated into a mesoporous Zr-based MOF (NU-1000) via an impregnation method in aqueous media, resulting in the hybrid material, PW12@NU-1000. The POM@MOF composite was characterized by a suite of physical methods, indicating the retention of crystallinity and high porosity of the parent MOF. The hybrid material was also stable to leaching in aqueous media at varying pH. Finally, the material was tested as a heterogeneous catalyst for the oxidation of 2-chloroethyl ethyl sulfide using hydrogen peroxide as the oxidant. PW12@NU-1000 was shown to have a higher catalytic activity than either of the individual constituents alone.

Photodegradation of methyl red under visible light by mesoporous carbon nitride

NASA Astrophysics Data System (ADS)

Hu, Yueyue; Zhang, Min; Xiao, Zaozao; Jiang, Tao; Yan, Bing; Li, Jian

2018-02-01

Mesoporous carbon nitride (mpg-C3N4) with tunable microstructure has been successfully prepared through a simple polymerization reaction of cyanamide by a nano hard-templating approach. The obtained materials have been characterized using X-ray diffraction (XRD), N2 adsorption, and Fourier transform infrared (FT-IR) spectroscopy. The results show that the pore diameter of the mpg-C3N4 materials can be easily tuned from 3.8 to 10.5 nm. The mpg-C3N4 materials are demonstrated to exhibit much higher visible light photocatalytic activity than that of g-C3N4 for the degradation of aqueous methyl red (MR). The high surface areas and large pore volume contributed to the efficient visible light photocatalytic activity.

Mesoporous Polymer Frameworks from End-Reactive Bottlebrush Copolymers

DOE PAGES

Altay, Esra; Nykypanchuk, Dmytro; Rzayev, Javid

2017-08-07

Reticulated nanoporous materials generated by versatile molecular framework approaches are limited to pore dimensions on the scale of the utilized rigid molecular building blocks (<5 nm). The inherent flexibility of linear polymers precludes their utilization as long framework connectors for the extension of this strategy to larger length scales. We report a method for the fabrication of mesoporous frameworks by using bottlebrush copolymers with reactive end blocks serving as rigid macromolecular interconnectors with directional reactivity. End-reactive bottlebrush copolymers with pendant alkene functionalities were synthesized by a combination of controlled radical polymerization and polymer modification protocols. Ru-catalyzed cross-metathesis cross-linking of bottlebrushmore » copolymers with two reactive end blocks resulted in the formation of polymer frameworks where isolated cross-linked domains were interconnected with bottlebrush copolymer bridges. The resulting materials were characterized by a continuous network pore structure with average pore sizes of 9–50 nm, conveniently tunable by the length of the utilized bottlebrush copolymer building blocks. As a result, the materials fabrication strategy described in this work expands the length scale of molecular framework materials and provides access to mesoporous polymers with a molecularly tunable reticulated pore structure without the need for templating, sacrificial component etching, or supercritical fluid drying.« less

Synthesis and structure of pyridine-functionalized mesoporous SBA-15 organosilicas and their application for sorption of diclofenac

NASA Astrophysics Data System (ADS)

Barczak, Mariusz

2018-02-01

A series of pyridine-functionalized mesoporous silicas have been prepared for the first time via direct co-condensation of tetraethoxysilane (TEOS) and 2-(2-pyridyl)ethyltrimethoxysilane (PETS) using the block copolymer Pluronic P123 as a structure-directing agent. The obtained materials were fully characterized by a wide range of instrumental techniques and employed as adsorbents for the removal of a diclofenac which is considered a priority hazardous drug. The synthesized materials exhibit a high adsorption capacities and rapid adsorption rates. The structural and adsorption properties depend largely on the relative amount of PETS/TEOS ratio: the gradual degradation of ordered structure and porosity was observed with the increasing amount of PETS. However due to the highest loading of pyridine units the most structurally degraded material had the highest adsorption uptake (631 mg g-1) indicating that the surface chemistry plays - along with porosity - an important role in governing the adsorption process. The experimental adsorption data were modelled using the Langmuir, Freundlich and Langmuir-Freundlich isotherms - among them the Langmuir-Freundlich model turned out to be the most suitable for describing adsorption behaviour of diclofenac onto the materials. The collected data show that the pyridine-functionalized mesoporous silicas can be a promising absorbent of pharmaceuticals.

Hierarchical porous carbon aerogel derived from bagasse for high performance supercapacitor electrode.

PubMed

Hao, Pin; Zhao, Zhenhuan; Tian, Jian; Li, Haidong; Sang, Yuanhua; Yu, Guangwei; Cai, Huaqiang; Liu, Hong; Wong, C P; Umar, Ahmad

2014-10-21

Renewable, cost-effective and eco-friendly electrode materials have attracted much attention in the energy conversion and storage fields. Bagasse, the waste product from sugarcane that mainly contains cellulose derivatives, can be a promising candidate to manufacture supercapacitor electrode materials. This study demonstrates the fabrication and characterization of highly porous carbon aerogels by using bagasse as a raw material. Macro and mesoporous carbon was first prepared by carbonizing the freeze-dried bagasse aerogel; consequently, microporous structure was created on the walls of the mesoporous carbon by chemical activation. Interestingly, it was observed that the specific surface area, the pore size and distribution of the hierarchical porous carbon were affected by the activation temperature. In order to evaluate the ability of the hierarchical porous carbon towards the supercapacitor electrode performance, solid state symmetric supercapacitors were assembled, and a comparable high specific capacitance of 142.1 F g(-1) at a discharge current density of 0.5 A g(-1) was demonstrated. The fabricated solid state supercapacitor displayed excellent capacitance retention of 93.9% over 5000 cycles. The high energy storage ability of the hierarchical porous carbon was attributed to the specially designed pore structures, i.e., co-existence of the micropores and mesopores. This research has demonstrated that utilization of sustainable biopolymers as the raw materials for high performance supercapacitor electrode materials is an effective way to fabricate low-cost energy storage devices.

Investigation of the Mesoporous Metal-Organic Framework as a New Platform To Study the Transport Phenomena of Biomolecules.

PubMed

Chen, Yao; Hong, Seongmin; Fu, Chung-Wei; Hoang, Tran; Li, Xiao; Valencia, Veronica; Zhang, Zhenjie; Perman, Jason A; Ma, Shengqian

2017-03-29

Mesoporous materials, Tb-mesoMOF and MCM-41, were used to study the transport phenomena of biomolecules entering the interior pores from solution. Vitamins B 12 and B 2 were successfully encapsulated into these mesoporous materials, whereas Tb-mesoMOF (0.33 g of B 12 /g, 0.01 g of B 2 /g) adsorbed a higher amount of vitamin per mass than MCM-41 (0.21 g of B 12 /g, 0.002 g of B 2 /g). The diffusion mechanism of the biomolecules entering Tb-mesoMOF was evaluated using a mathematical model. The Raman spectroscopy studies showed vitamin B 12 has been encapsulated within Tb-mesoMOF's pores, and evaluation of the peak shifts indicated strong interactions linking vitamin B 12 's pyrroline moiety with Tb-mesoMOF's triazine and benzoate rings. Because of these stronger interactions between the vitamins and Tb-mesoMOF, longer egress times were observed than with MCM-41.

Incessant formation of chain-like mesoporous silica with a superior binding capacity for mercury.

PubMed

Ravi, S; Selvaraj, M

2014-04-14

A novel incessant formation of chain like mesoporous silica (ICMS) has been easily materialized using a mixed surfactant (Pluronic P123 and FC-4) as a structuring reagent in conjunction with a thiol precursor (3-MPS) through a one-pot synthetic method. A particular thiol concentration facilitated the interaction of the micelle head groups to form long-chain micelles, where FC-4 enhanced further growth. The rapid interactions of the micelles and the condensation of silicic acid and its oligomeric derivatives by coordinating 3-MPS through hydrogen bonding interactions leads to form ICMS. The characterization results for the ICMS illustrated that it has an ordered hexagonal pore geometry. The capability of the ICMS for Hg(2+) adsorption was extensively studied under different optimal parameters and the adsorption isothermal values clearly fit with the Langmuir and Freundlich isothermal plots. This novel material exhibited an unprecedentedly high binding affinity toward even microgram levels of mercury ions in wastewater, compared to other thiol-based mesoporous silica.

In situ synthesis, characterization, and catalytic performance of tungstophosphoric acid encapsulated into the framework of mesoporous silica pillared clay.

PubMed

Li, Baoshan; Liu, Zhenxing; Han, Chunying; Ma, Wei; Zhao, Songjie

2012-07-01

Mesoporous silica pillared clay (SPC) incorporated with tungstophosphoric acid (HPW) has been synthesized via in situ introducing P and W source in the acidic suspension of the clay interlayer template during the formation of the silica pillared clay. The samples were characterized by XRD, XRF, FT-IR, TG-DTA, N(2) adsorption-desorption, and SEM techniques. The results showed that the HPW formed by in situ method has been effectively introduced into the framework of mesoporous silica pillared clay and its Keggin structure remained perfectly after formation of the materials. In addition, samples with similar HPW loadings were also prepared by impregnation method using SPC as the support. HPW in the incorporated samples was better dispersed into the silica pillared clay than in the impregnated samples. The results of catalytic tests indicated that the encapsulated materials demonstrated better catalytic performance than the impregnated samples in oxidative desulfurization (ODS) of dibenzothiophene (DBT). Copyright © 2012 Elsevier Inc. All rights reserved.

Synthesis and Supercapacitor Performance of Polyaniline/Nitrogen-Doped Ordered Mesoporous Carbon Composites

NASA Astrophysics Data System (ADS)

Xie, Kangjun; Zhang, Manman; Yang, Yang; Zhao, Long; Qi, Wei

2018-05-01

The electrochemical property of ordered mesoporous carbon (OMC) can be changed significantly due to the incorporating of electron-donating heteroatoms into OMC. Here, we demonstrate the successful fabrication of nitrogen-doped ordered mesoporous carbon (NOMC) materials to be used as carbon substrates for loading polyaniline (PANI) by in situ polymerization. Compared with NOMC, the PANI/NOMC prepared with a different mass ratio of PANI and NOMC exhibits remarkably higher electrochemical specific capacitance. In a typical three-electrode configuration, the hybrid has a specific capacitance about 276.1 F/g at 0.2 A/g with a specific energy density about 38.4 Wh/kg. What is more, the energy density decreases very slowly with power density increasing, which is a different phenomenon from other reports. PANI/NOMC materials exhibit good rate performance and long cycle stability in alkaline electrolyte ( 80% after 5000 cycles). The fabrication of PANI/NOMC with enhanced electrochemical properties provides a feasible route for promoting its applications in supercapacitors.

Template-directed assembly of metal-chalcogenide nanocrystals into ordered mesoporous networks.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vamvasakis, Ioannis; Subrahmanyam, Kota S.; Kanatzidis, Mercouri G.

Although great progress in the synthesis of porous networks of metal and metal oxide nanoparticles with highly accessible pore surface and ordered mesoscale pores has been achieved, synthesis of assembled 3D mesostructures of metal-chalcogenide nanocrystals is still challenging. In this work we demonstrate that ordered mesoporous networks, which comprise well-defined interconnected metal sulfide nanocrystals, can be prepared through a polymer-templated oxidative polymerization process. The resulting self-assembled mesostructures that were obtained after solvent extraction of the polymer template impart the unique combination of light-emitting metal chalcogenide nanocrystals, three-dimensional open-pore structure, high surface area, and uniform pores. We show that the poremore » surface of these materials is active and accessible to incoming molecules, exhibiting high photocatalytic activity and stability, for instance, in oxidation of 1-phenylethanol into acetophenone. We demonstrate through appropriate selection of the synthetic components that this method is general to prepare ordered mesoporous materials from metal chalcogenide nanocrystals with various sizes and compositions.« less

Soft-Templating Synthesis of N-Doped Mesoporous Carbon Nanospheres for Enhanced Oxygen Reduction Reaction.

PubMed

Bayatsarmadi, Bita; Zheng, Yao; Jaroniec, Mietek; Qiao, Shi Zhang

2015-07-01

The development of ordered mesoporous carbon materials with controllable structures and improved physicochemical properties by doping heteroatoms such as nitrogen into the carbon framework has attracted a lot of attention, especially in relation to energy storage and conversion. Herein, a series of nitrogen-doped mesoporous carbon spheres (NMCs) was synthesized via a facile dual soft-templating procedure by tuning the nitrogen content and carbonization temperature. Various physical and (electro)chemical properties of the NMCs have been comprehensively investigated to pave the way for a feasible design of nitrogen-containing porous carbon materials. The optimized sample showed a favorable electrocatalytic activity as evidenced by a high kinetic current and positive onset potential for oxygen reduction reaction (ORR) due to its large surface area, high pore volume, good conductivity, and high nitrogen content, which make it a highly efficient ORR metal-free catalyst in alkaline solutions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Room Temperature Co-Precipitation Synthesis of Magnetite Nanoparticles in a Large pH Window with Different Bases.

PubMed

Mascolo, Maria Cristina; Pei, Yongbing; Ring, Terry A

2013-11-28

Magnetite nanoparticles (Fe₃O₄) represent the most promising materials in medical applications. To favor high-drug or enzyme loading on the nanoparticles, they are incorporated into mesoporous materials to form a hybrid support with the consequent reduction of magnetization saturation. The direct synthesis of mesoporous structures appears to be of interest. To this end, magnetite nanoparticles have been synthesized using a one pot co-precipitation reaction at room temperature in the presence of different bases, such as NaOH, KOH or (C₂H₅)₄NOH. Magnetite shows characteristics of superparamagnetism at room temperature and a saturation magnetization (Ms) value depending on both the crystal size and the degree of agglomeration of individual nanoparticles. Such agglomeration appears to be responsible for the formation of mesoporous structures, which are affected by the pH, the nature of alkali, the slow or fast addition of alkaline solution and the drying modality of synthesized powders.

Amino-functionalized MCM-41 and MCM-48 for the removal of chromate and arsenate.

PubMed

Benhamou, A; Basly, J P; Baudu, M; Derriche, Z; Hamacha, R

2013-08-15

The aim of the present work was to investigate the efficiency of three amino-functionalized (hexadecylamine, dodecylamine, and dimethyldodecylamine) mesoporous silicas (MCM-41 and MCM-48) toward the adsorption of arsenate and chromate. Hexadecylamine-functionalized materials were characterized; BET surface areas, pore volumes, and sizes decreased with the functionalization, whereas XRD patterns show that the hexagonal structure of MCM-41 and the cubic structure of MCM-48 were not modified. The zeta potential decreases with pH and the highest arsenate and chromate removal was observed at the lowest pHs. Adsorption of chromium and arsenate was significantly enhanced after functionalization and amino-functionalized MCM-41 adsorb larger amounts of arsenate when compared to expanded MCM-48 materials. Chromate sorption capacities increased with the chain length and the larger capacities were obtained with hexadecylamine-functionalized mesoporous silicas. Mesoporous silicas modified by dimethyldodecylamine exhibited the higher arsenate sorption capacities. Copyright © 2013 Elsevier Inc. All rights reserved.

Correlation between mesopore volume of carbon supports and the immobilization of laccase from Trametes versicolor for the decolorization of Acid Orange 7.

PubMed

Ramírez-Montoya, Luis A; Hernández-Montoya, Virginia; Montes-Morán, Miguel A; Cervantes, Francisco J

2015-10-01

Immobilization of laccase from Trametes versicolor was carried out using carbon supports prepared from different lignocellulosic wastes. Enzymes were immobilized by physical adsorption. Taguchi methodology was selected for the design of experiments regarding the preparation of the carbon materials, which included the use of activating agents for the promotion of mesoporosity. A good correlation between the mesopore volumes of the carbon supports and the corresponding laccase loadings attained was observed. Specifically, the chemical activation of pecan nut shell with FeCl3 led to a highly mesoporous material that also behaved as the most efficient support for the immobilization of laccase. This particular laccase/carbon support system was used as biocatalyst for the decolorization of aqueous solutions containing Acid Orange 7. Mass spectrometry coupled to a liquid chromatograph allowed us to identify the products of the dye degradation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis of butenes through 2-butanol dehydration over mesoporous materials produced from ferrierite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeong, Soyeon; Kim, Hyeonjoo; Bae, Jung A.

2012-05-20

Mesoporous materials synthesized from commercial ferrierite (MMZ-FER) were applied to butanol dehydration. The MMZ-FER was produced by disassembling ferrierite into unit structures in the presence of an alkali solution, adding a surfactant as a templating material, followed by hydrothermal treatment. The effect of the alkali/(Si+Al) ratio in the disassembling step on the characteristics of the catalyst and butanol dehydration performance were investigated. The MMZ-FER materials, synthesized in a condition in which the NaOH/(Si + Al) mole ratio in the disassembling step was 0.67 and 1.0, demonstrated similar textural properties to those of MCM-41. Many weak acid sites developed on themore » MMZ-FER(0.67) and MMZ-FER(1.0) samples, which is attributed to the creation of ferrierite-induced acid sites. The MMZ-FER materials showed excellent catalytic activity, selectivity, and stability during the dehydration of 2-butanol.« less

Controlling drug delivery kinetics from mesoporous titania thin films by pore size and surface energy.

PubMed

Karlsson, Johan; Atefyekta, Saba; Andersson, Martin

2015-01-01

The osseointegration capacity of bone-anchoring implants can be improved by the use of drugs that are administrated by an inbuilt drug delivery system. However, to attain superior control of drug delivery and to have the ability to administer drugs of varying size, including proteins, further material development of drug carriers is needed. Mesoporous materials have shown great potential in drug delivery applications to provide and maintain a drug concentration within the therapeutic window for the desired period of time. Moreover, drug delivery from coatings consisting of mesoporous titania has shown to be promising to improve healing of bone-anchoring implants. Here we report on how the delivery of an osteoporosis drug, alendronate, can be controlled by altering pore size and surface energy of mesoporous titania thin films. The pore size was varied from 3.4 nm to 7.2 nm by the use of different structure-directing templates and addition of a swelling agent. The surface energy was also altered by grafting dimethylsilane to the pore walls. The drug uptake and release profiles were monitored in situ using quartz crystal microbalance with dissipation (QCM-D) and it was shown that both pore size and surface energy had a profound effect on both the adsorption and release kinetics of alendronate. The QCM-D data provided evidence that the drug delivery from mesoporous titania films is controlled by a binding-diffusion mechanism. The yielded knowledge of release kinetics is crucial in order to improve the in vivo tissue response associated to therapeutic treatments.

One-pot hydrothermal synthesis of mesoporous Zn(x)Cd(1-x)S/reduced graphene oxide hybrid material and its enhanced photocatalytic activity.

PubMed

Wang, Xinwei; Tian, Hongwei; Cui, Xiaoqiang; Zheng, Weitao; Liu, Yichun

2014-09-14

We successfully synthesized mesoporous Zn(x)Cd(1-x)S/reduced graphene oxide (Z(x)CSG) hybrid materials as photocatalysts using a facile one-pot hydrothermal reaction, in which graphene oxide (GO) was easily reduced (RGO), and simultaneously Zn(x)Cd(1-x)S (Z(x)CS) nanoparticles (NPs) with a mesoporous structure were uniformly dispersed on the RGO sheets. By well tuning the band gap from 3.42 to 2.21 eV by changing the molar ratio of Zn/Cd (or Zn content), Z(x)CSG with an optimal zinc content has been found to have a significant absorption in the visible light (VL) region. In addition, under VL irradiation (λ > 420 nm), Z(x)CSG also showed zinc content-dependent photocatalytic efficiencies for the degradation of methylene blue (MB). Our findings are that, among Z(x)CSG, Z(0.4)CSG displayed not only a superior photodegradation efficiency of MB (98%), but also good removal efficiency of total organic carbon (TOC) (67%). Furthermore, Z(0.4)CSG had a high photocatalytic stability, and could be used repeatedly. The enhanced photocatalytic activity for Z(0.4)CSG could be attributed to a synergistic effect between mesoporous Z(x)CS NPs and RGO, including the optimal band gap and the moderate conduction band position for ZxCS (compared to CdS), efficient separation and transfer ability of photogenerated electron/hole pairs in the presence of RGO sheets, and relatively high surface area for both mesoporous Z(x)CS NPs and RGO.

Facile synthesis and unique physicochemical properties of three-dimensionally ordered macroporous magnesium oxide, gamma-alumina, and ceria-zirconia solid solutions with crystalline mesoporous walls.

PubMed

Li, Huining; Zhang, Lei; Dai, Hongxing; He, Hong

2009-05-18

Three-dimensionally (3D) ordered macroporous (3DOM) MgO, gamma-Al(2)O(3), Ce(0.6)Zr(0.4)O(2), and Ce(0.7)Zr(0.3)O(2) with polycrystalline mesoporous walls have been successfully fabricated with the triblock copolymer EO(106)PO(70)EO(106) (Pluronic F127) and regularly packed monodispersive polymethyl methacrylate (PMMA) microspheres as the template and magnesium, aluminum, cerium and zirconium nitrate(s), or aluminum isopropoxide as the metal source. The as-synthesized metal oxides were characterized by means of techniques such as X-ray diffraction (XRD), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), Fourier transform infrared (FT-IR), high-resolution scanning electron microscopy (HRSEM), high-resolution transmission electron microscopy/selected area electron diffraction (HRTEM/SAED), BET, carbon dioxide temperature-programmed desorption (CO(2)-TPD), and hydrogen temperature-programmed reduction (H(2)-TPR). It is shown that the as-fabricated MgO, gamma-Al(2)O(3), Ce(0.6)Zr(0.4)O(2), and Ce(0.7)Zr(0.3)O(2) samples possessed single-phase polycrystalline structures and displayed a 3DOM architecture; the MgO, Ce(0.6)Zr(0.4)O(2), and Ce(0.7)Zr(0.3)O(2) samples exhibited worm-hole-like mesoporous walls, whereas the gamma-Al(2)O(3) samples exhibited 3D ordered mesoporous walls. The solvent (ethanol or water) nature and concentration, metal precursor, surfactant, and drying condition have an important impact on the pore structure and surface area of the final product. The introduction of surfactant F127 to the synthesis system could significantly enhance the surface areas of the 3DOM metal oxides. With PMMA and F127 in a 40% ethanol solution, one can generate well-arrayed 3DOM MgO with a surface area of 243 m(2)/g and 3DOM Ce(0.6)Zr(0.4)O(2) with a surface area of 100 m(2)/g; with PMMA and F127 in an ethanol-HNO(3) solution, one can obtain 3DOM gamma-Al(2)O(3)with a surface area of 145 m(2)/g. The 3DOM MgO and 3DOM gamma-Al(2)O(3) samples showed excellent CO(2) adsorption behaviors, whereas the 3DOM Ce(0.6)Zr(0.4)O(2) sample exhibited exceptional low-temperature reducibility. The unique physicochemical properties associated with the copresence of 3DOM and mesoporous walls make these porous materials ideal candidates for applications in heterogeneous catalysis and CO(2) adsorption.

Preparation of Ultraviolet Curing Type Silicone Rubbers Containing Mesoporous Silica Fillers.

PubMed

Abdullah, Nawfel; Hossain, Md Shahriar A; Fatehmulla, Amanullah; Farooq, Wazirzada Aslam; Islam, Md Tofazzal; Miyamoto, Nobuyoshi; Bando, Yoshio; Kamachi, Yuichiro; Malgras, Victor; Yamauchi, Yusuke; Suzuki, Norihiro

2018-01-01

Here we have been focusing on mesoporous silica (MPS) as inorganic filler material to improve the mechanical strength of silicone rubbers. The MPS particles are more effective in reducing the coefficient of thermal expansion (CTE) and hardening silicone rubber composites when compared to commercially available nonporous silica particles. In this study, we utilize ultraviolet curing type silicone rubbers and prepare MPS composites according to a simple single-step method. From an industrial viewpoint, simplifying the fabrication processes is critical. The thermal stability and mechanical strength are examined in detail in order to showcase the effectiveness of MPS particles as filler materials.

Method for rapidly producing microporous and mesoporous materials

DOEpatents

Coronado, P.R.; Poco, J.F.; Hrubesh, L.W.; Hopper, R.W.

1997-11-11

An improved, rapid process is provided for making microporous and mesoporous materials, including aerogels and pre-ceramics. A gel or gel precursor is confined in a sealed vessel to prevent structural expansion of the gel during the heating process. This confinement allows the gelation and drying processes to be greatly accelerated, and significantly reduces the time required to produce a dried aerogel compared to conventional methods. Drying may be performed either by subcritical drying with a pressurized fluid to expel the liquid from the gel pores or by supercritical drying. The rates of heating and decompression are significantly higher than for conventional methods. 3 figs.

Synthesis of fluidized CO2 sorbents based on diamine coordinated to Metal-Organic Frameworks via direct conversion of metal oxides supported on mesoporous silica.

PubMed

Luz, Ignacio; Soukri, Mustapha; Lail, Marty

2018-06-06

A general and efficient method for shaping MOFs into fluidized forms has been developed via direct conversion of metal oxides supported on fluidized mesoporous silica. The resulting fluidized MOF hybrid materials containing diamines coordinated at the open metal sites have been studied as CO2 solid sorbents from post-combustion flue gas showing similar performance than their bulk counterparts. These novel fluidized MOF hybrid materials can be used for other applications involving fluidized bed reactor configurations, in which MOFs have never been considered. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, Characterization, and Gas-Sensing Properties of Mesoporous Nanocrystalline Sn(x)Ti(1-x)O2.

PubMed

Zhong, Cheng; Lin, Zhidong; Guo, Fei; Wang, Xuehua

2015-06-01

A nanocomposite mesoporous material composed by SnO2 and TiO2 with the size of -5-9 nm were prepared via a facile wet-chemical approach combining with an annealing process. The microstructure of obtained Sn(x)Ti(1-x)O2 powders were characterized by X-ray diffraction, X-ray Photo-electronic Spectroscopy, scanning electron microscope, transmission electron microscope and nitrogen adsorption-desorption experiment. The gas sensing performances to several gases of the mesoporous material were studied. The sensors of Sn(x)Ti(1-x)O2 (ST10, with 9.1% Ti) exhibited very high responses to volatile organic compounds at 160 degrees C. The order of the responses to volatile gases based on ST10 was ethanol > formaldehyde > acetone > toluene > benzene > methane. Sensor based on ST10 displays a highest sensitivity to hydrogen at 200 degrees C. Sensor responses to H2 at 200 degrees C have been measured and analyzed in a wide concentration range from 5 to 2000 ppm. The solid solution Sn(x)Ti(1-x)O2 can be served as a potential gas-sensing material for a broad range of future sensor applications.

Thermal decomposition pathway of undoped and doped zinc layered gallate nanohybrid with Fe 3+, Co 2+ and Ni 2+ to produce mesoporous and high pore volume carbon material

NASA Astrophysics Data System (ADS)

Ghotbi, Mohammad Yeganeh; bin Hussein, Mohd Zobir; Yahaya, Asmah Hj; Abd Rahman, Mohd Zaki

2009-12-01

A series of brucite-like materials, undoped and doped zinc layered hydroxide nitrate with 2% (molar) Fe 3+, Co 2+ and Ni 2+ were synthesized. Organic-inorganic nanohybrid material with gallate anion as a guest, and zinc hydroxide nitrate, as an inorganic layered host was prepared by the ion-exchange method. The nanohybrid materials were heat-treated at various temperatures, 400-700 °C. X-ray diffraction, thermal analysis and also Fourier transform infrared results showed that incorporation of the doping agents within the zinc layered hydroxide salt layers has enhanced the heat-resistivity of the nanohybrid materials in the thermal decomposition pathway. Porous carbon materials can be obtained from the heat-treating the nanohybrids at 600 and 700 °C. Calcination of the nanohybrids at 700 °C under nitrogen atmosphere produces mesoporous and high pore volume carbon materials.

Surface plasmon resonance-induced photocatalysis by Au nanoparticles decorated mesoporous g-C{sub 3}N{sub 4} nanosheets under direct sunlight irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tonda, Surendar; Kumar, Santosh; Shanker, Vishnu, E-mail: vishnu@nitw.ac.in

Highlights: • The Au/mp-g-C{sub 3}N{sub 4} was synthesized via a template-free and green in situ strategy. • Au/mp-g-C{sub 3}N{sub 4} nanosheets possesses high surface area and porous structure. • Au/mp-g-C{sub 3}N{sub 4} showed dramatic photocurrent response and photocatalytic activity. • The high performance is due to SPR of Au and mesoporous structure. • Au/mp-g-C{sub 3}N{sub 4} nanosheets exhibited high photostability. - Abstract: In recent years, surface plasmon-induced photocatalytic materials with tunable mesoporous framework have attracted considerable attention in energy conversion and environmental remediation. Herein we report a novel Au nanoparticles decorated mesoporous graphitic carbon nitride (Au/mp-g-C{sub 3}N{sub 4}) nanosheets viamore » a template-free and green in situ photo-reduction method. The synthesized Au/mp-g-C{sub 3}N{sub 4} nanosheets exhibit a strong absorption edge in visible and near-IR region owing to the surface plasmon resonance effect of Au nanoparticles. More attractively, Au/mp-g-C{sub 3}N{sub 4} exhibited much higher photocatalytic activity than that of pure mesoporous and bulk g-C{sub 3}N{sub 4} for the degradation of rhodamine B under sunlight irradiation. Furthermore, the photocurrent and photoluminescence studies demonstrated that the deposition of Au nanoparticles on the surface of mesoporous g-C{sub 3}N{sub 4} could effectively inhibit the recombination of photogenerated charge carriers leading to the enhanced photocatalytic activity. More importantly, the synthesized Au/mp-g-C{sub 3}N{sub 4} nanosheets possess high reusability. Hence, Au/mp-g-C{sub 3}N{sub 4} could be promising photoactive material for energy and environmental applications.« less

Nanocrystalline Heterojunction Materials

DOEpatents

Elder, Scott H.; Su, Yali; Gao, Yufei; Heald, Steve M.

2004-02-03

Mesoporous nanocrystalline titanium dioxide heterojunction materials and methods of making the same are disclosed. In one disclosed embodiment, materials comprising a core of titanium dioxide and a shell of a molybdenum oxide exhibit a decrease in their photoadsorption energy as the size of the titanium dioxide core decreases.

Effect of electrolytes on proteins physisorption on ordered mesoporous silica materials.

PubMed

Salis, Andrea; Medda, Luca; Cugia, Francesca; Monduzzi, Maura

2016-01-01

This short review highlights the effect of electrolytes on the performance of proteins-mesoporous silica conjugates which can open interesting perspectives in biotechnological fields, particularly nanomedicine and biocatalysis. Indeed therapeutic proteins and peptides represent a challenging innovation for several kinds of diseases, but since their self-life in biological fluids is very short, they need a stealth protective carrier. Similarly, enzymes need a solid support to improve thermal stability and to allow for recycling. Ordered mesoporous silica materials represent a valid choice as widely demonstrated. Both proteins and silica mesoporous materials possess charged surfaces, and here, the crucial role of pH, buffer, ionic strength and electrolyte type is posed in relation with loading/release of proteins onto/from the silica support through the analysis of adsorption and release processes. A delicate interplay of electrostatic and van der Waals interactions arises from considering electrolytes' effects on the two different charged surfaces. Clear outcomes concern the effect of pH and ionic strength. Protein loading onto the silica matrix is favored by an adsorbing solution having a pH close to the protein pI, and by a high ionic strength that reduces the Debye length. Release is instead favored by an adsorbing solution characterized by an intermediate ionic strength, close to the physiological values. Significant specific ions effects are shown to affect both proteins and silica matrices, as well as protein adsorption onto silica matrices. Further work is needed to quantify specific ion effects on the preservation of the biological activity, and on the release performance. Copyright © 2015 Elsevier B.V. All rights reserved.

Al-doped TiO{sub 2} mesoporous material supported Pd with enhanced catalytic activity for complete oxidation of ethanol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Jing, E-mail: mlczjsls123@163.com; Mu, Wentao, E-mail: mwt15035687833@163.com; Su, Liqing, E-mail: suliqing0163@163.com

Pd catalysts supported on Al-doped TiO{sub 2} mesoporous materials were evaluated in complete oxidation of ethanol. The catalysts synthesized by wet impregnation based on evaporation-induced self-assembly were characterized by X-ray diffraction, measurement of pore structure, XPS, FT-IR, temperature programmed reduction and TEM. Characteristic results showed that the aluminium was doped into the lattice of mesoporous anatase TiO{sub 2} to form Al-O-Ti defect structure. Catalytic results revealed that Al-doped catalysts were much more active than the pristine one, especially at low temperature (≤200 °C). This should be ascribed to the introduction of aluminium ions that suppressed the strong metal-support interaction andmore » increased the active sites of Pd oxides, enhanced the stabilized anatase TiO{sub 2}, improved well dispersed high valence palladium species with high reducibility and enriched chemisorption oxygen. - Graphical abstract: Al-doped Pd/TiO{sub 2} exhibited optimal catalytic performance for ethanol oxidation and CO{sub 2} yield by the suppression of SMSI. - Highlights: • Palladium catalysts supported on Al-doped TiO{sub 2} mesoporous materials were studied. • The introduction of Al can enhance anatase stabilization and increase defect TiO{sub 2}. • The Pd/Al-TiO{sub 2} catalysts show higher ethanol conversion and CO{sub 2} yield than Pd/TiO{sub 2}. • The influence of Al on SMSI and catalytic performance were evaluated by TPR and XPS.« less

Quaternary ammonium-functionalized MCM-48 mesoporous silica as a sorbent for the dispersive solid-phase extraction of endocrine disrupting compounds in water.

PubMed

Zhang, Shijuan; Lu, Fengli; Ma, Xiaoyun; Yue, Mingbo; Li, Yanxin; Liu, Jiammin; You, Jinmao

2018-07-06

MCM-48 mesoporous silica was functionalized with dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, a quaternary ammonium salt with a long hydrophobic chain, to prepare a new sorbent for the dispersive solid-phase extraction (DSPE) of seven endocrine disrupting compounds (EDCs) including 4-hexylphenol, 4-octylphenol, 4-nonylphenol, bisphenol A, estrone, 17β-estradiol and estriol in water. A series of differently functionalized MCM-48 materials were also synthesized, and they served as reference materials to study the mechanism. The developed DSPE method was combined with HPLC with fluorescence detection to evaluate the adsorption performance. The results indicated that the quaternary ammonium-functionalized MCM-48 mesoporous silica can be used as ideal sorbent for EDCs in water with recoveries of higher than 95% due to the electrostatic interactions and hydrophobic effect. Hydrogen bonding and π-π interactions in other synthesized materials could lead to about 25-30% increase in recoveries, but the results for polyhydroxy compounds were still not satisfying. The quaternary ammonium-functionalized MCM-48 mesoporous silica was successfully applied to the DSPE of EDCs in real water samples. The optimum extraction conditions were sorbent amount, 15 mg; desorption time; 5 min; elution volume, 0.8 mL; sample pH 3.0; and salt addition, 5 g/L. The limits of detection were in the range of 1.2-2.6 ng/L, while the limits of quantitation were in the range of 4.3-8.3 ng/L. Copyright © 2018 Elsevier B.V. All rights reserved.

A novel strategy to design sustained-release poorly water-soluble drug mesoporous silica microparticles based on supercritical fluid technique.

PubMed

Li-Hong, Wang; Xin, Che; Hui, Xu; Li-Li, Zhou; Jing, Han; Mei-Juan, Zou; Jie, Liu; Yi, Liu; Jin-Wen, Liu; Wei, Zhang; Gang, Cheng

2013-09-15

The organic solvent solution immersion method was often used to achieve the loading of the drugs into mesoporous silica, but the drugs that have loaded into the pores of the mesoporous silica would inevitable migrate from the inside to the external surface or near the outside surface during the process of drying. Hence, it often leads to the pores of mesoporous materials not be fully utilized, and results in a low drug loading efficiency and a fast releasing rate. The purpose of this study was to develop a novel drug loading strategy to avoid soluble component migration during the process of drying, then, to prepare poorly water-soluble drug mesoporous silica microparticles with higher drug loading efficiency and longer sustained-release time. Ibuprofen was used as model drug. The microparticles were prepared by a novel method based on mesoporous silica and supercritical fluid (SCF) technique. The drug-loaded mesoporous silica microparticles prepared by SCF technique were analyzed by thermogravimetric analysis (TGA), N2 adsorption/desorption, scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC). In vitro releasing study was used to evaluate the sustained-release effect of the drug-loaded microparticles. By virtue of the high diffusibility and the high dissolving capacity of the supercritical carbon dioxide (SCF-CO2), the poorly water-soluble drugs, ibuprofen, entered the pores of the mesoporous silica. The amount and the depth of ibuprofen entered the pores of the mesoporous silica by SCF technique were both larger than those by the solution immersion method. It was found that ibuprofen loaded into the mesoporous silica by SCF technique was amorphous and the largest amount of the ibuprofen loaded into the mesoporous silica by SCF technique could reach 386 mg/g (w/w, ibuprofen/SiO2), it was more than that by the solution immersion method. In vitro releasing study showed that the sustained-release effect of ibuprofen in the samples prepared by SCF technique was 50% in 15 min and 90% in 60 min. It was longer than that prepared by the solution immersion method. Present study showed that sustained-release poorly water-soluble drug mesoporous silica microparticle based on SCF technique has twofold advantages. One is the larger drug loading amount in internal pores of the mesoporous silica, the other is the longer drug releasing time. Copyright © 2013 Elsevier B.V. All rights reserved.

From molecular chemistry to hybrid nanomaterials. Design and functionalization.

PubMed

Mehdi, Ahmad; Reye, Catherine; Corriu, Robert

2011-02-01

This tutorial review reports upon the organisation and functionalization of two families of hybrid organic-inorganic materials. We attempted to show in both cases the best ways permitting the organisation of materials in terms of properties at the nanometric scale. The first family concerns mesoporous hybrid organic-inorganic materials prepared in the presence of a structure-directing agent. We describe the functionalization of the channel pores of ordered mesoporous silica, that of the silica framework, as well as the functionalization of both of them simultaneously. This family is currently one of the best supports for exploring polyfunctional materials, which can provide a route to interactive materials. The second family concerns lamellar hybrid organic-inorganic materials which is a new class of nanostructured materials. These materials were first obtained by self-assembly, as a result of van der Waals interactions of bridged organosilica precursors containing long alkylene chains during the sol-gel process, without any structure directing agent. This methodology has been extended to functional materials. It is also shown that such materials can be obtained from monosilylated precursors.

Facile and green synthesis of mesoporous Co3O4 nanocubes and their applications for supercapacitors.

PubMed

Liu, Xiangmei; Long, Qing; Jiang, Chunhui; Zhan, Beibei; Li, Chen; Liu, Shujuan; Zhao, Qiang; Huang, Wei; Dong, Xiaochen

2013-07-21

Nanostructured Co3O4 materials attracted significant attention due to their exceptional electrochemical (pseudo-capacitive) properties. However, rigorous preparation conditions are needed to control the size (especially nanosize), morphology and size distribution of the products obtained by conventional methods. Herein, we describe a novel one step shape-controlled synthesis of uniform Co3O4 nanocubes with a size of 50 nm with the existence of mesoporous carbon nanorods (meso-CNRs). In this synthesis process, meso-CNRs not only act as a heat receiver to directly obtain Co3O4 eliminating the high-temperature post-calcination, but also control the morphology of the resulting Co3O4 to form nanocubes with uniform distribution. More strikingly, mesoporous Co3O4 nanocubes are obtained by further thermal treatment. The structure and morphology of the samples were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. A possible formation mechanism of mesoporous Co3O4 nanocubes is proposed here. Electrochemical tests have revealed that the prepared mesoporous Co3O4 nanocubes demonstrate a remarkable performance in supercapacitor applications due to the porous structure, which endows fast ion and electron transfer.

Investigation of Free-Standing Plasmonic Mesoporous Ag/CMK-8-Nafion Composite Membrane for the Removal of Organic Pollutants with 254-nm UV Irradiation

NASA Astrophysics Data System (ADS)

Tseng, Chuan Ming; Chen, Hsin Liang; Lai, Sz Nian; Chen, Ming Shiung; Peng, Chien Jung; Li, Chia Jui; Hung, Wei Hsuan

2017-05-01

"Carbon-based material" has demonstrated a great potential on water purification due to its strong physical adsorption to organic pollutants in the water. Three-dimensional cubic ordered mesoporous carbon (CMK-8), one of the well-known ordered mesoporous carbons, was prepared by using nanocasting method with mesoporous silica (KIT-6) as the template. In this study, CMK-8 blended with Nafion polymer to form a free-standing mesoporous CMK-8-Nafion composite membrane. The synthesis of high crystallinity CMK-8 was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). More than 80% methyl orange (MO) removal efficiency was observed under 254-nm UV irradiation after 120 min. Ninety-two percent recycling performance was remained after four recycling tests, which indicated a reliable servicing lifetime for the water purification. Furthermore, an additional layer of plasmonic silver nanoparticles (Ag NPs) was integrated into this CMK-8-Nafion membrane for higher pollutant removal efficiency, attributing from the generation of plasmon-resonance hot electrons from Ag NPs. A 4-in. CMK-8-Nafion composite membrane was also fabricated for the demonstration of potential large-scale utilization.

Hierarchical porous silicon carbide with controlled micropores and mesopores for electric double layer capacitors

NASA Astrophysics Data System (ADS)

Kim, Myeongjin; Oh, Ilgeun; Kim, Jooheon

2015-05-01

Three-dimensional hierarchical micro and mesoporous silicon carbide spheres (MMPSiC) are prepared by the template method and carbonization reaction via the aerosol spray drying method. The mesopores are generated by the self-assembly of the structure-directing agents, whereas the micropores are derived from the partial evaporation of Si atoms during carbonization. To investigate the effect of mesopore size on electrochemical performance, three types of MMPSiC with different mesopore size were fabricated by using three different structure directing agents (cetyltriethylammonium bromide (CTAB), Polyethylene glycol hexadecyl ether (Brij56), and Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123)). The MMPSiC electrode prepared with Brij56 exhibits the highest charge storage capacity with a specific capacitance of 253.7 F g-1 at a scan rate of 5 mV s-1 and 87.9% rate performance from 5 to 500 mV s-1 in 1 M Na2SO4 aqueous electrolyte. The outstanding electrochemical performance might be because of the ideal mesopore size, which effectively reduces the resistant pathways for ion diffusion in the pores and provides a large accessible surface area for ion transport/charge storage. These encouraging results demonstrate that the MMPSiC prepared with Brij56 is a promising candidate for high performance electrode materials for supercapacitors.

High-response and low-temperature nitrogen dioxide gas sensor based on gold-loaded mesoporous indium trioxide.

PubMed

Li, Shan; Cheng, Ming; Liu, Guannan; Zhao, Lianjing; Zhang, Bo; Gao, Yuan; Lu, Huiying; Wang, Haiyu; Zhao, Jing; Liu, Fangmeng; Yan, Xu; Zhang, Tong; Lu, Geyu

2018-04-10

Nitrogen dioxide (NO 2 ), as a typical threatening atmospheric pollutant, is hazardous to the environment and human health. Thus, the development of a gas sensor with high response and low detection limit for NO 2 detection is highly important. The highly ordered mesoporous indium trioxide (In 2 O 3 ) prepared by simple nanocasting method using mesoporous silica as template and decorated with Au nanoparticles was investigated for NO 2 detection. The prepared materials were characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Characterization results showed that the samples exhibited ordered mesostructure and were successfully decorated with Au. The gas sensing performance of the sensors based on a series of Au-loaded mesoporous In 2 O 3 were systematically investigated. The Au loading level strongly affected the sensing performance toward NO 2 . The optimal sensor, which was based on 0.5 wt% Au-loaded In 2 O 3 , displayed high sensor response and low detection limit of 10 ppb at low operating temperature of 65 °C. The excellent sensing properties were mainly attributed to the ordered mesoporous structure and the catalytic performance of Au. We believe that the Au-loaded mesoporous In 2 O 3 can provide a promising platform for NO 2 gas sensors with excellent performance. Copyright © 2018 Elsevier Inc. All rights reserved.

Adsorption of a catalytically accessible polyoxometalate in a mesoporous channel-type metal–organic framework

DOE PAGES

Buru, Cassandra T.; Li, Peng; Mehdi, B. Layla; ...

2017-05-24

A Keggin-type polyoxometalate (H 3PW 12O 40) was incorporated into a mesoporous Zr-based MOF (NU-1000) via an impregnation method in aqueous media, resulting in the hybrid material, PW 12@NU-1000. The POM@MOF composite was characterized by a suite of physical methods, indicating the retention of crystallinity and high porosity of the parent MOF. The hybrid material was also stable to leaching in aqueous media at varying pH. Lastly, the material was tested as a heterogeneous catalyst for the oxidation of 2-chloroethyl ethyl sulfide using hydrogen peroxide as the oxidant. PW 12@NU-1000 was shown to have a higher catalytic activity than eithermore » of the individual constituents alone.« less

High-performance TiO(2) from Baker's yeast.

PubMed

He, Wen; Cui, Jingjie; Yue, Yuanzheng; Zhang, Xudong; Xia, Xi; Liu, Hong; Lui, Suwen

2011-02-01

Based on the biomineralization assembly concept, a biomimetic approach has been developed to synthesize high-performance mesoporous TiO(2). The key step of this approach is to apply Baker's yeast cells as biotemplates for deriving the hierarchically ordered mesoporous anatase structure. The mechanism of formation of the yeast-TiO(2) is revealed by characterizing its morphology, microstructure, and chemical composition. The yeast-TiO(2) exhibits outstanding photocatalytic performance. Under visible-light irradiation, the removal efficiency of chemical oxygen demand (COD) and color of the paper industry wastewater has reached 80.3% and nearly 100%, respectively. The approach may open new vistas for fabricating advanced mesoporous materials under ambient condition. Copyright © 2010 Elsevier Inc. All rights reserved.

Potential of ordered mesoporous silica for oral delivery of poorly soluble drugs.

PubMed

Vialpando, Monica; Martens, Johan A; Van den Mooter, Guy

2011-08-01

The use of ordered mesoporous silica is one of the more recent and rapidly developing formulation techniques for enhancing the solubility of poorly water-soluble drugs. Their large surface area and pore volume make ordered mesoporous silica materials excellent candidates for efficient drug loading and rapid release. While this new approach offers many promising advantages, further research is still necessary to elucidate the molecular mechanisms and to improve our scientific insight into the behavior of this system. In this review, the significant developments to date are presented and research challenges highlighted. Aspects of downstream processability are discussed in view of their special bulk powder properties and unique pore architecture. Lastly, perspectives for successful oral dosage form development are presented.

New strategy for surface functionalization of periodic mesoporous silica based on meso-HSiO1.5.

PubMed

Xie, Zhuoying; Bai, Ling; Huang, Suwen; Zhu, Cun; Zhao, Yuanjin; Gu, Zhong-Ze

2014-01-29

Organic functionalization of periodic mesoporous silicas (PMSs) offers a way to improve their excellent properties and wide applications owing to their structural superiority. In this study, a new strategy for organic functionalization of PMSs is demonstrated by hydrosilylation of the recently discovered "impossible" periodic mesoporous hydridosilica, meso-HSiO1.5. This method overcomes the disadvantages of present pathways for organic functionalization of PMSs with organosilica. Moreover, compared to the traditional functionalization on the surface of porous silicon by hydrosilylation, the template-synthesized meso-HSiO1.5 is more flexible to access functional-groups-loaded PMSs with adjustable microstructures. The new method and materials will have wider applications based on both the structure and surface superiorities.

Research on the Ordered Mesoporous Silica for Tobacco Harm Reduction

NASA Astrophysics Data System (ADS)

Wang, Y.; Y Li, Z.; Ding, J. X.; Hu, Z. J.; Liu, Z.; Zhou, G.; Huang, T. H.

2017-12-01

For reducting tobacco harm, this paper prepared an ordered mesoporous silica by using triblock copolymer Pluronic P123 as template. The property of this material was characterized by the X-ray scattering spectrum(XRD), Transmission electron microscopy(TEM), Scanning electron microscopy (SEM) and Nitrogen adsorption/desorption. Then this ordered mesoporous silica was added into the cigarette filter in order to researching its effect of cigarette harm index. The result shows that the feature of SBA-15 was grain morphology, ordered arrangement, tubular porous 2-D hexagonal structure. The application of SBA-15 in cigarette filter can selectively reduce harmful components in cigarette smoke such as crotonaldehyde, hydrogen cyanide, benzo pyrene and tar. The synthesized SBA-15 could properly reduce cigarette harm index.

Fabrication of Nitrogen-Doped Hollow Mesoporous Spherical Carbon Capsules for Supercapacitors.

PubMed

Chen, Aibing; Xia, Kechan; Zhang, Linsong; Yu, Yifeng; Li, Yuetong; Sun, Hexu; Wang, Yuying; Li, Yunqian; Li, Shuhui

2016-09-06

A novel "dissolution-capture" method for the fabrication of nitrogen-doped hollow mesoporous spherical carbon capsules (N-HMSCCs) with high capability for supercapacitor is developed. The fabrication process is performed by depositing mesoporous silica on the surface of the polyacrylonitrile nanospheres, followed by a dissolution-capture process occurring in the polyacrylonitrile core and silica shell. The polyacrylonitrile core is dissolved by dimethylformamide treatment to form a hollow cavity. Then, the polyacrylonitrile is captured into the mesochannel of silica. After carbonization and etching of silica, N-HMSCCs with uniform mesopore size are produced. The N-HMSCCs show a high specific capacitance of 206.0 F g(-1) at a current density of 1 A g(-1) in 6.0 M KOH due to its unique hollow nanostructure, high surface area, and nitrogen content. In addition, 92.3% of the capacitance of N-HMSCCs still remains after 3000 cycles at 5 A g(-1). The "dissolution-capture" method should give a useful enlightenment for the design of electrode materials for supercapacitor.

APTES-modified mesoporous silicas as the carriers for poorly water-soluble drug. Modeling of diflunisal adsorption and release

NASA Astrophysics Data System (ADS)

Geszke-Moritz, Małgorzata; Moritz, Michał

2016-04-01

Four mesoporous siliceous materials such as SBA-16, SBA-15, PHTS and MCF functionalized with (3-aminopropyl)triethoxysilane were successfully prepared and applied as the carriers for poorly water-soluble drug diflunisal. Several techniques including nitrogen sorption analysis, XRD, TEM, FTIR and thermogravimetric analysis were employed to characterize mesoporous matrices. Adsorption isotherms were analyzed using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models. In order to find the best-fit isotherm for each model, both linear and nonlinear regressions were carried out. The equilibrium data were best fitted by the Langmuir isotherm model revealing maximum adsorption capacity of 217.4 mg/g for aminopropyl group-modified SBA-15. The negative values of Gibbs free energy change indicated that the adsorption of diflunisal is a spontaneous process. Weibull release model was employed to describe the dissolution profile of diflunisal. At pH 4.5 all prepared mesoporous matrices exhibited the improvement of drug dissolution kinetics as compared to the dissolution rate of pure diflunisal.

Encapsulation of ultrafine metal-oxide nanoparticles within mesopores for biomass-derived catalytic applications† †Electronic supplementary information (ESI) available: Experimental section, additional characterization and reaction results. See DOI: 10.1039/c7sc04724j

PubMed Central

Fang, Ruiqi; Tian, Panliang; Yang, Xianfeng

2018-01-01

The development of efficient encapsulation strategies has attracted intense interest for preparing highly active and stable heterogeneous metal catalysts. However, issues related to low loadings, costly precursors and complex synthesis processes restrict their potential applications. Herein, we report a novel and general strategy to encapsulate various ultrafine metal-oxides nanoparticles (NPs) into the mesoporous KIT-6. The synthesis is facile, which only involves self-assembly of a metal–organic framework (MOF) precursor in the silica mesopores and a subsequent calcination process to transform the MOF into metal-oxide NPs. After the controlled calcination, the metal-oxide NPs produced from MOF decomposition are exclusively confined and uniformly distributed in the mesopores of KIT-6 with high metal loadings. Benefitting from the encapsulation effects, as-synthesized Co@KIT-6 materials exhibit superior catalytic activity and recycling stability in biomass-derived HMF oxidation under mild reaction conditions. PMID:29675231

Synthesis and characterization of mesoporous indium tin oxide possessing an electronically conductive framework.

PubMed

Emons, Theo T; Li, Jianquan; Nazar, Linda F

2002-07-24

The new mesoporous transparent conducting oxide based on indium-tin-oxide, meso-ITO, has been synthesized by a modified sol-gel method, using CTAB as the surfactant. Critical was the employment of triethanolamine to control the rate of hydrolysis and inhibit deposition of the bulk oxides. Removal of the surfactant by calcination yielded a relatively well-ordered worm-hole motif arrangement of pores visible in the TEM and stable to 400 degrees C. BET measurements revealed no hysteresis in the absorption-desorption isotherm, consistent with a narrow pore-size distribution (between 20 and 40 A depending on the In:Sn ratio); surface areas ranged between 270 and 310 m2/g. This colorless material is the first mesoporous oxide exhibiting substantial framework conductivity, with a conductivity at 25 degrees C of 1.2 x 10-3 S/cm. This distinguishes it from mesoporous mixed-valence transition-metal oxides that exhibit weak hopping semiconductor behavior and much lower conductivity.

Wafer-scale Fabrication of Non-Polar Mesoporous GaN Distributed Bragg Reflectors via Electrochemical Porosification.

PubMed

Zhu, Tongtong; Liu, Yingjun; Ding, Tao; Fu, Wai Yuen; Jarman, John; Ren, Christopher Xiang; Kumar, R Vasant; Oliver, Rachel A

2017-03-27

Distributed Bragg reflectors (DBRs) are essential components for the development of optoelectronic devices. For many device applications, it is highly desirable to achieve not only high reflectivity and low absorption, but also good conductivity to allow effective electrical injection of charges. Here, we demonstrate the wafer-scale fabrication of highly reflective and conductive non-polar gallium nitride (GaN) DBRs, consisting of perfectly lattice-matched non-polar (11-20) GaN and mesoporous GaN layers that are obtained by a facile one-step electrochemical etching method without any extra processing steps. The GaN/mesoporous GaN DBRs exhibit high peak reflectivities (>96%) across the entire visible spectrum and wide spectral stop-band widths (full-width at half-maximum >80 nm), while preserving the material quality and showing good electrical conductivity. Such mesoporous GaN DBRs thus provide a promising and scalable platform for high performance GaN-based optoelectronic, photonic, and quantum photonic devices.

Composite Biomaterials Based on Sol-Gel Mesoporous Silicate Glasses: A Review

PubMed Central

Baino, Francesco; Fiorilli, Sonia; Vitale-Brovarone, Chiara

2017-01-01

Bioactive glasses are able to bond to bone and stimulate the growth of new tissue while dissolving over time, which makes them ideal materials for regenerative medicine. The advent of mesoporous glasses, which are typically synthesized via sol-gel routes, allowed researchers to develop a broad and versatile class of novel biomaterials that combine superior bone regenerative potential (compared to traditional melt-derived glasses) with the ability of incorporating drugs and various biomolecules for targeted therapy in situ. Mesoporous glass particles can be directly embedded as a bioactive phase within a non-porous (e.g., microspheres), porous (3D scaffolds) or injectable matrix, or be processed to manufacture a surface coating on inorganic or organic (macro)porous substrates, thereby obtaining hierarchical structures with multiscale porosity. This review provides a picture of composite systems and coatings based on mesoporous glasses and highlights the challenges for the future, including the great potential of inorganic–organic hybrid sol-gel biomaterials. PMID:28952496

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Dongdong, E-mail: lidongchem@sina.cn; Zhu, Yuntao; Liang, Zhiqiang

Highlights: ► The synthesized mesoporous hydroxyapatite has nanostructure and bioactivity. ► The materials have high surface area and amino group. ► The materials show higher drug loading and slower release rate than pure HAP. - Abstract: Mesoporous nanosized hydroxyapatite (HAP) functionalized by alendronate (ALN) was synthesized using cationic surfactant CTAB as template. The structural, morphological and textural properties were fully characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and N{sub 2} adsorption/desorption. Then the obtained materials were performed as drug delivery carriers using ibuprofen (IBU) as a model drug to investigate their drug storage/releasemore » properties in simulated body fluid (SBF). The materials showed relatively slower release rate compared with HAP due to the ionic interaction between -NH{sub 3}{sup +} on the matrix and -COO{sup −}belongs to IBU. The system provides a new concept for improving the drug loading or slowing down the release rate.« less

A universal cooperative assembly-directed method for coating of mesoporous TiO2 nanoshells with enhanced lithium storage properties

PubMed Central

Guan, Bu Yuan; Yu, Le; Li, Ju; Lou, Xiong Wen (David)

2016-01-01

TiO2 is exceptionally useful, but it remains a great challenge to develop a universal method to coat TiO2 nanoshells on different functional materials. We report a one-pot, low-temperature, and facile method that can rapidly form mesoporous TiO2 shells on various inorganic, organic, and inorganic-organic composite materials, including silica-based, metal, metal oxide, organic polymer, carbon-based, and metal-organic framework nanomaterials via a cooperative assembly-directed strategy. In constructing hollow, core-shell, and yolk-shell geometries, both amorphous and crystalline TiO2 nanoshells are demonstrated with excellent control. When used as electrode materials for lithium ion batteries, these crystalline TiO2 nanoshells composed of very small nanocrystals exhibit remarkably long-term cycling stability over 1000 cycles. The electrochemical properties demonstrate that these TiO2 nanoshells are promising anode materials. PMID:26973879

Tunable mesoporous bilayer photonic resins with chiral nematic structures and actuator properties.

PubMed

Khan, Mostofa K; Hamad, Wadood Y; Maclachlan, Mark J

2014-04-16

Chiral nematic structures with different helical pitch from layer to layer are embedded into phenol-formaldehyde bilayer resin composite films using cellulose nanocrystals (CNCs) as templates. Selective removal of CNCs results in mesoporous resins with different pore size and helical pitch between the layers. Consequently, these materials exhibit photonic properties by selectively reflecting lights of two different wavelengths and concomitant actuation properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and characterization of mesoporous ZnS with narrow size distribution of small pores

NASA Astrophysics Data System (ADS)

Nistor, L. C.; Mateescu, C. D.; Birjega, R.; Nistor, S. V.

2008-08-01

Pure, nanocrystalline cubic ZnS forming a stable mesoporous structure was synthesized at room temperature by a non-toxic surfactant-assisted liquid liquid reaction, in the 9.5 10.5 pH range of values. The appearance of an X-ray diffraction (XRD) peak in the region of very small angles (˜ 2°) reveals the presence of a porous material with a narrow pore size distribution, but with an irregular arrangement of the pores, a so-called worm hole or sponge-like material. The analysis of the wide angle XRD diffractograms shows the building blocks to be ZnS nanocrystals with cubic structure and average diameter of 2 nm. Transmission electron microscopy (TEM) investigations confirm the XRD results; ZnS crystallites of 2.5 nm with cubic (blende) structure are the building blocks of the pore walls with pore sizes from 1.9 to 2.5 nm, and a broader size distribution for samples with smaller pores. Textural measurements (N2 adsorption desorption isotherms) confirm the presence of mesoporous ZnS with a narrow range of small pore sizes. The relatively lower surface area of around 100 m2/g is attributed to some remaining organic molecules, which are filling the smallest pores. Their presence, confirmed by IR spectroscopy, seems to be responsible for the high stability of the resulting mesoporous ZnS as well.

Controlled release of ibuprofen by meso-macroporous silica

NASA Astrophysics Data System (ADS)

Santamaría, E.; Maestro, A.; Porras, M.; Gutiérrez, J. M.; González, C.

2014-02-01

Structured meso-macroporous silica was successfully synthesized from an O/W emulsion using decane as a dispersed phase. Sodium silicate solution, which acts as a silica source and a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (EO19PO39EO19) denoted as P84 was used in order to stabilize the emulsion and as a mesopore template. The materials obtained were characterized through transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angle X-ray diffraction scattering (SAXS) and nitrogen adsorption-desorption isotherms. Ibuprofen (IBU) was selected as the model drug and loaded into ordered meso-macroporous materials. The effect of the materials’ properties on IBU drug loading and release was studied. The results showed that the loading of IBU increases as the macropore presence in the material is increased. The IBU adsorption process followed the Langmuir adsorption isotherm. A two-step release process, consisting of an initial fast release and then a slower release was observed. Macropores enhanced the adsorption capacity of the material; this was probably due to the fact that they allowed the drug to access internal pores. When only mesopores were present, ibuprofen was probably adsorbed on the mesopores close to the surface. Moreover, the more macropore present in the material, the slower the release behaviour observed, as the ibuprofen adsorbed in the internal pores had to diffuse along the macropore channels up to the surface of the material. The material obtained from a highly concentrated emulsion was functionalized with amino groups using two methods, the post-grafting mechanism and the co-condensation mechanism. Both routes improve IBU adsorption in the material and show good behaviour as a controlled drug delivery system.

Biocompatibility, endocytosis, and intracellular trafficking of mesoporous silica and polystyrene nanoparticles in ovarian cancer cells: effects of size and surface charge groups

PubMed Central

Ekkapongpisit, Maneerat; Giovia, Antonino; Follo, Carlo; Caputo, Giuseppe; Isidoro, Ciro

2012-01-01

Background and methods Nanoparticles engineered to carry both a chemotherapeutic drug and a sensitive imaging probe are valid tools for early detection of cancer cells and to monitor the cytotoxic effects of anticancer treatment simultaneously. Here we report on the effect of size (10–30 nm versus 50 nm), type of material (mesoporous silica versus polystyrene), and surface charge functionalization (none, amine groups, or carboxyl groups) on biocompatibility, uptake, compartmentalization, and intracellular retention of fluorescently labeled nanoparticles in cultured human ovarian cancer cells. We also investigated the involvement of caveolae in the mechanism of uptake of nanoparticles. Results We found that mesoporous silica nanoparticles entered via caveolae-mediated endocytosis and reached the lysosomes; however, while the 50 nm nanoparticles permanently resided within these organelles, the 10 nm nanoparticles soon relocated in the cytoplasm. Naked 10 nm mesoporous silica nanoparticles showed the highest and 50 nm carboxyl-modified mesoporous silica nanoparticles the lowest uptake rates, respectively. Polystyrene nanoparticle uptake also occurred via a caveolae-independent pathway, and was negatively affected by serum. The 30 nm carboxyl-modified polystyrene nanoparticles did not localize in lysosomes and were not toxic, while the 50 nm amine-modified polystyrene nanoparticles accumulated within lysosomes and eventually caused cell death. Ovarian cancer cells expressing caveolin-1 were more likely to endocytose these nanoparticles. Conclusion These data highlight the importance of considering both the physicochemical characteristics (ie, material, size and surface charge on chemical groups) of nanoparticles and the biochemical composition of the cell membrane when choosing the most suitable nanotheranostics for targeting cancer cells. PMID:22904626

Facile synthesis of highly stable and well-dispersed mesoporous ZrO(2)/carbon composites with high performance in oxidative dehydrogenation of ethylbenzene.

PubMed

Li, Qiang; Xu, Jie; Wu, Zhangxiong; Feng, Dan; Yang, Jianping; Wei, Jing; Wu, Qingling; Tu, Bo; Cao, Yong; Zhao, Dongyuan

2010-09-28

Highly ordered mesoporous ZrO(2)/carbon (FDU-15) composites have been synthesized via a facile evaporation induced triconstituent co-assembly (EISA) approach by using Pluronic F127 as a template and zirconium oxychloride octahydrate and resol as Zr and carbon sources. The synthesized mesoporous composites exhibit a highly ordered two-dimensional (2-D) hexagonal mesostructure with relatively high specific surface areas (up to 947 m(2) g(-1)), pore sizes around 3.8 nm and high pore volumes (up to 0.71 cm(3) g(-1)). The results clearly show that the crystalline zirconia nanoparticles (ca. 1.9-3.9 nm) are well-dispersed in amorphous matrices of the ordered mesoporous carbon FDU-15 materials, which construct the nanocomposites. The ordered mesostructures of the obtained ZrO(2)/FDU-15 composites can be well-retained even at the high pyrolysis temperature (up to 900 degrees C), suggesting a high thermal stability. The zirconia content of the ZrO(2)/FDU-15 composites can be tunable in a wide range (up to 47%). Moreover, the resultant mesoporous ZrO(2)/FDU-15 composites exhibit high catalytic activity in oxidative dehydrogenation (ODH) of ethylbenzene (EB) to styrene (ST), with high ethylbenzene conversion (59.6%) and styrene selectivity (90.4%), which is mainly attributed to the synergistic catalytic effect between the oxygen-containing groups located on the carbon pore walls and weakly basic sites of the nanocrystalline ZrO(2). Furthermore, the high specific surface areas and opening pore channels are also responsible for their high catalytic activity. Therefore, it is a very promising catalyst material in styrene production on an industrial scale.

Biological Activity of Mesoporous Dendrimer-Coated Titanium Dioxide: Insight on the Role of the Surface-Interface Composition and the Framework Crystallinity.

PubMed

Milowska, Katarzyna; Rybczyńska, Aneta; Mosiolek, Joanna; Durdyn, Joanna; Szewczyk, Eligia M; Katir, Nadia; Brahmi, Younes; Majoral, Jean-Pierre; Bousmina, Mosto; Bryszewska, Maria; El Kadib, Abdelkrim

2015-09-16

Hitherto, the field of nanomedicine has been overwhelmingly dominated by the use of mesoporous organosilicas compared to their metal oxide congeners. Despite their remarkable reactivity, titanium oxide-based materials have been seldom evaluated and little knowledge has been gained with respect to their "structure-biological activity" relationship. Herein, a fruitful association of phosphorus dendrimers (both "ammonium-terminated" and "phosphonate-terminated") and titanium dioxide has been performed by means of the sol-gel process, resulting in mesoporous dendrimer-coated nanosized crystalline titanium dioxide. A similar organo-coating has been reproduced using single branch-mimicking dendrimers that allow isolation of an amorphous titanium dioxide. The impact of these materials on red blood cells was evaluated by studying cell hemolysis. Next, their cytotoxicity toward B14 Chinese fibroblasts and their antimicrobial activity were also investigated. Based on their variants (cationic versus anionic terminal groups and amorphous versus crystalline titanium dioxide phase), better understanding of the role of the surface-interface composition and the nature of the framework has been gained. No noticeable discrimination was observed for amorphous and crystalline material. In contrast, hemolysis and cytotoxicity were found to be sensitive to the nature of the interface composition, with the ammonium-terminated dendrimer-coated titanium dioxide being the most hemolytic and cytotoxic material. This surface-functionalization opens the door for creating a new synergistic machineries mechanism at the cellular level and seems promising for tailoring the biological activity of nanosized organic-inorganic hybrid materials.

Effects of pore topology and iron oxide core on doxorubicin loading and release from mesoporous silica nanoparticles

NASA Astrophysics Data System (ADS)

Ronhovde, Cicily J.; Baer, John; Larsen, Sarah C.

2017-06-01

Mesoporous silica nanoparticles (MSNs) have a network of pores that give rise to extremely high specific surface areas, making them attractive materials for applications such as adsorption and drug delivery. The pore topology can be readily tuned to achieve a variety of structures such as the hexagonally ordered Mobil Crystalline Material 41 (MCM-41) and the disordered "wormhole" (WO) mesoporous silica (MS) structure. In this work, the effects of pore topology and iron oxide core on doxorubicin loading and release were investigated using MSNs with pore diameters of approximately 3 nm and sub-100 nm particle diameters. The nanoparticles were loaded with doxorubicin, and the drug release into phosphate-buffered saline (PBS, 10 mM, pH 7.4) at 37 °C was monitored by fluorescence spectroscopy. The release profiles were fit using the Peppas model. The results indicated diffusion-controlled release for all samples. Statistically significant differences were observed in the kinetic host-guest parameters for each sample due to the different pore topologies and the inclusion of an iron oxide core. Applying a static magnetic field to the iron oxide core WO-MS shell materials did not have a significant impact on the doxorubicin release. This is the first time that the effects of pore topology and iron oxide core have been isolated from pore diameter and particle size for these materials.

Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) technology of mercury removal and stabilization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Xiangdong; Liu, Jun; Fryxell, G.E.

1997-09-01

This paper explains the technology developed to produce Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) for mercury removal from aqueous wastewater and from organic wastes. The characteristics of SAMMS materials, including physical characteristics and mercury loading, and its application for mercury removal and stabilization are discussed. Binding kinetics and binding speciations are reported. Preliminary cost estimates are provided for producing SAMMS materials and for mercury removal from wastewater. The characteristics of SAMMS in mercury separation were studied at PNNL using simulated aqueous tank wastes and actual tritiated pump oil wastes from Savannah River Site; preliminary results are outlined. 47 refs., 16more » figs., 16 tabs.« less

Free-radical sensing by using naphthalimide based mesoporous silica (MCM-41) nanoparticles: A combined fluorescence and cellular imaging study

NASA Astrophysics Data System (ADS)

Jha, Gaurav; Roy, Subhasis; Sahu, Prabhat Kumar; Banerjee, Somnath; Anoop, N.; Rahaman, Abdur; Sarkar, Moloy

2018-01-01

Keeping in mind the advantages of material-based systems over simple molecule-based systems, we have designed and developed three inorganic-organic hybrid systems by anchoring 1,8-naphthalimide derivatives to mesoporous silica nanoparticles for detection of free radicals. Prior to photophysical study, systems are characterized by spectroscopic, microscopic and thermo-gravimetric techniques. Steady state and time-resolved fluorescence studies demonstrate that the hydrazine based system is senstive towards detection of various free radicals. Cellular imaging study reveals cell permeability and toxicity study demonstrates the non-toxic nature of the material. These studies have suggested that present system has the potential to be used in various biological applications.

Direct observation of macrostructure formation of hierarchically structured meso-macroporous aluminosilicates with 3D interconnectivity by optical microscope.

PubMed

Lemaire, Arnaud; Rooke, Joanna Claire; Chen, Li-Hua; Su, Bao-Lian

2011-03-15

Hierarchically structured spongy meso-macroporous aluminosilicates with high tetrahedral aluminum content were synthesized from a mixture of single molecular alkoxide precursor, (sec-BuO)2-Al-O-Si(OEt)3, already containing Si-O-Al bonds, and a silica coreactant, tetramethoxysilane (TMOS). The spontaneous byproduct templated macroporous structure formation has been directly visualized using in situ high-resolution optical microscopy (OM), allowing the crucial observation of a microbubble dispersion which is directly correlated to the macrostructure observed by electronic microscopies (SEM and TEM). This discovery leads to a comparative study with meso-macroporous pure metal oxide and to a proposal of the formation mechanism of meso-macroporous aluminosilicates with 3D interconnectivity. The aluminosilicate phase/microbubbles emulsion is produced by a phase separation process occurring between the aluminosilicate nanoparticles and the liquid hydrolysis-condensation reaction byproducts (water, methanol, ethanol, and butanol). The use of alkoxysilane improves the heterocondensation rates between the highly reactive aluminum alkoxide part of the single precursor and added silica species but, above all, leads to the spontaneous generation of an unusual meso-macroporosity in alkaline media. The particles obtained at pH = 13.0 featured regular micrometer-sized macrospheres separated by very thin mesoporous walls and connected by submicrometric openings, providing a 3D interconnectivity. The slight increase in pH value to 13.5 induced significant modifications in morphology and textural properties due to the slower gelification process of the aluminosilicate phase, resulting in the formation of an aluminosilicate material constituted of 1-2 µm large independent hollow mesoporous spheres.

Gated Silica Mesoporous Materials in Sensing Applications.

PubMed

Sancenón, Félix; Pascual, Lluís; Oroval, Mar; Aznar, Elena; Martínez-Máñez, Ramón

2015-08-01

Silica mesoporous supports (SMSs) have a large specific surface area and volume and are particularly exciting vehicles for delivery applications. Such container-like structures can be loaded with numerous different chemical substances, such as drugs and reporters. Gated systems also contain addressable functions at openings of voids, and cargo delivery can be controlled on-command using chemical, biochemical or physical stimuli. Many of these gated SMSs have been applied for drug delivery. However, fewer examples of their use in sensing protocols have been reported. The approach of applying SMSs in sensing uses another concept-that of loading pores with a reporter and designing a capping mechanism that is selectively opened in the presence of a target analyte, which results in the delivery of the reporter. According to this concept, we provide herein a complete compilation of published examples of probes based on the use of capped SMSs for sensing. Examples for the detection of anions, cations, small molecules and biomolecules are provided. The diverse range of gated silica mesoporous materials presented here highlights their usefulness in recognition protocols.

Superior capacitive performance of hydrochar-based porous carbons in aqueous electrolytes.

PubMed

Fuertes, Antonio B; Sevilla, Marta

2015-03-01

Biomass-based highly porous carbons with excellent performances in aqueous electrolyte-based supercapacitors have been developed. The synthesis of these materials is based on the chemical activation of biomass-based hydrochar. The addition of melamine to the activation mixture leads to porous carbons with a porosity consisting of micropores/small mesopores. Furthermore, melamine promotes the introduction of nitrogen heteroatoms in the carbon framework, along with abundant oxygen functionalities, to improve the wettability. The materials produced in the presence or absence of melamine exhibit high specific capacitances in aqueous electrolytes (>270 F g(-1) in H2 SO4 and >190 F g(-1) in Li2SO4). Additionally, the mesopores present in the melamine-based micro-/mesoporous carbons notably improve the ion-transport kinetics, especially in Li2SO4. Furthermore, in Li2SO4, they remain stable up to a cell voltage of 1.6 V; thus exhibiting superior energy and power characteristics than those in H2 SO4. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gated Silica Mesoporous Materials in Sensing Applications

PubMed Central

Sancenón, Félix; Pascual, Lluís; Oroval, Mar; Aznar, Elena; Martínez-Máñez, Ramón

2015-01-01

Silica mesoporous supports (SMSs) have a large specific surface area and volume and are particularly exciting vehicles for delivery applications. Such container-like structures can be loaded with numerous different chemical substances, such as drugs and reporters. Gated systems also contain addressable functions at openings of voids, and cargo delivery can be controlled on-command using chemical, biochemical or physical stimuli. Many of these gated SMSs have been applied for drug delivery. However, fewer examples of their use in sensing protocols have been reported. The approach of applying SMSs in sensing uses another concept—that of loading pores with a reporter and designing a capping mechanism that is selectively opened in the presence of a target analyte, which results in the delivery of the reporter. According to this concept, we provide herein a complete compilation of published examples of probes based on the use of capped SMSs for sensing. Examples for the detection of anions, cations, small molecules and biomolecules are provided. The diverse range of gated silica mesoporous materials presented here highlights their usefulness in recognition protocols. PMID:26491626

Enhanced thermal properties of novel shape-stabilized PEG composite phase change materials with radial mesoporous silica sphere for thermal energy storage.

PubMed

Min, Xin; Fang, Minghao; Huang, Zhaohui; Liu, Yan'gai; Huang, Yaoting; Wen, Ruilong; Qian, Tingting; Wu, Xiaowen

2015-08-11

Radial mesoporous silica (RMS) sphere was tailor-made for further applications in producing shape-stabilized composite phase change materials (ss-CPCMs) through a facile self-assembly process using CTAB as the main template and TEOS as SiO2 precursor. Novel ss-CPCMs composed of polyethylene glycol (PEG) and RMS were prepared through vacuum impregnating method. Various techniques were employed to characterize the structural and thermal properties of the ss-CPCMs. The DSC results indicated that the PEG/RMS ss-CPCM was a promising candidate for building thermal energy storage applications due to its large latent heat, suitable phase change temperature, good thermal reliability, as well as the excellent chemical compatibility and thermal stability. Importantly, the possible formation mechanisms of both RMS sphere and PEG/RMS composite have also been proposed. The results also indicated that the properties of the PEG/RMS ss-CPCMs are influenced by the adsorption limitation of the PEG molecule from RMS sphere with mesoporous structure and the effect of RMS, as the impurities, on the perfect crystallization of PEG.

One-pot synthesis of transition metal ion-chelating ordered mesoporous carbon/carbon nanotube composites for active and durable fuel cell catalysts

NASA Astrophysics Data System (ADS)

Dombrovskis, Johanna K.; Palmqvist, Anders E. C.

2017-07-01

Development of non-precious metal catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells with high activity and durability and with optimal water management properties is of outmost technological importance and highly challenging. Here we study the possibilities offered through judicious selection of small molecular precursors used for the formation of ordered mesoporous carbon-based non-precious metal ORR catalysts. By combining two complementary precursors, we present a one-pot synthesis that leads to a composite material consisting of transition metal ion-chelating ordered mesoporous carbon and multi-walled carbon nanotubes (TM-OMC/CNT). The resulting composite materials show high specific surface areas and a carbon structure that exhibits graphitic signatures. The synthesis procedure allows for tuning of the carbon structure, the surface area, the pore volume and the ratio of the two components of the composite. The TM-OMC/CNT composites were processed into membrane electrode assemblies and evaluated in single cell fuel cell measurements where they showed a combination of good ORR activity and very high durability.

Enhanced thermal properties of novel shape-stabilized PEG composite phase change materials with radial mesoporous silica sphere for thermal energy storage

PubMed Central

Min, Xin; Fang, Minghao; Huang, Zhaohui; Liu, Yan’gai; Huang, Yaoting; Wen, Ruilong; Qian, Tingting; Wu, Xiaowen

2015-01-01

Radial mesoporous silica (RMS) sphere was tailor-made for further applications in producing shape-stabilized composite phase change materials (ss-CPCMs) through a facile self-assembly process using CTAB as the main template and TEOS as SiO2 precursor. Novel ss-CPCMs composed of polyethylene glycol (PEG) and RMS were prepared through vacuum impregnating method. Various techniques were employed to characterize the structural and thermal properties of the ss-CPCMs. The DSC results indicated that the PEG/RMS ss-CPCM was a promising candidate for building thermal energy storage applications due to its large latent heat, suitable phase change temperature, good thermal reliability, as well as the excellent chemical compatibility and thermal stability. Importantly, the possible formation mechanisms of both RMS sphere and PEG/RMS composite have also been proposed. The results also indicated that the properties of the PEG/RMS ss-CPCMs are influenced by the adsorption limitation of the PEG molecule from RMS sphere with mesoporous structure and the effect of RMS, as the impurities, on the perfect crystallization of PEG. PMID:26261089

A Hierarchical MFI Zeolite with a Two-Dimensional Square Mesostructure.

PubMed

Shen, Xuefeng; Mao, Wenting; Ma, Yanhang; Xu, Dongdong; Wu, Peng; Terasaki, Osamu; Han, Lu; Che, Shunai

2018-01-15

A conceptual design and synthesis of ordered mesoporous zeolites is a challenging research subject in material science. Several seminal articles report that one-dimensional (1D) mesostructured lamellar zeolites are possibly directed by sheet-assembly of surfactants, which collapse after removal of intercalated surfactants. However, except for one example of two-dimensional (2D) hexagonal mesoporous zeolite, no other zeolites with ordered 2D or three-dimensional (3D) mesostructures have been reported. An ordered 2D mesoporous zeolite can be templated by a cylindrical assembly unit with specific interactions in the hydrophobic part. A template molecule with azobenzene in the hydrophobic tail and diquaternary ammonium in the hydrophilic head group directs hierarchical MFI zeolite with a 2D square mesostructure. The material has an elongated octahedral morphology, and quaternary, ordered, straight, square channels framed by MFI thin sheets expanded along the a-c planes and joined with 90° rotations. The structural matching between the cylindrical assembly unit and zeolite framework is crucial for mesostructure construction. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recent Advances in the Separation of Rare Earth Elements Using Mesoporous Hybrid Materials.

PubMed

Hu, Yimu; Florek, Justyna; Larivière, Dominic; Fontaine, Frédéric-Georges; Kleitz, Freddy

2018-05-27

Over the past decades, the need for rare earth elements (REEs) has increased substantially, mostly because these elements are used as valuable additives in advanced technologies. However, the difference in ionic radius between neighboring REEs is small, which renders an efficient sized-based separation extremely challenging. Among different types of extraction methods, solid-phase extraction (SPE) is a promising candidate, featuring high enrichment factor, rapid adsorption kinetics, reduced solvent consumption and minimized waste generation. The great challenge remains yet to develop highly efficient and selective adsorbents for this process. In this regard, ordered mesoporous materials (OMMs) possess high specific surface area, tunable pore size, large pore volume, as well as stable and interconnected frameworks with active pore surfaces for functionalization. Such features meet the requirements for enhanced adsorbents, not only providing huge reactional interface and large surface capable of accommodating guest species, but also enabling the possibility of ion-specific binding for enrichment and separation purposes. This short personal account summarizes some of the recent advances in the use of porous hybrid materials as selective sorbents for REE separation and purification, with particular attention devoted to ordered mesoporous silica and carbon-based sorbents. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Transition metal ion capture using functional mesoporous carbon made with 1,10-phenanthroline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chouyyok, Wilaiwan; Yantasee, Wassana; Shin, Yongsoon

2009-11-01

Functional mesoporous carbon has been built using 1,10-phenanthroline as the fundamental building block, resulting in a nanoporous, high surface area sorbent capable of selectively binding transition metal ions. This material had a specific surface area of 870 m2/g, an average pore size of about 30Å, and contained as much as 8.2 weight percent N. Under acidic conditions, where the 1,10-phenanthroline ligand is protonated, this material was found to be an effective anion exchange material for transition metal anions like PdCl4-2 and H2VO4-1. 1,10-phenanthroline functionalized mesoporous carbon (“Phen-FMC”) was found to have a high affinity for Cu(II), even down to amore » pH of 1. At pHs above 5, Phen-FMC was found to bind a variety of transition metal cations (e.g. Co(II), Ni(II), Zn(II), etc.) from filtered ground water, river water and seawater. Phen-FMC displayed rapid sorption kinetics with Co(II) in filtered river water, reaching equilibrium in less than an hour, and easily lowering the [Co(II)] to sub-ppb levels. Phen-FMC was found to be more effective for transition metal ion capture than ion exchange resin or activated carbon.« less

Mesoporous silicas with covalently immobilized β-cyclodextrin moieties: synthesis, structure, and sorption properties

NASA Astrophysics Data System (ADS)

Roik, Nadiia V.; Belyakova, Lyudmila A.; Trofymchuk, Iryna M.; Dziazko, Marina O.; Oranska, Olena I.

2017-09-01

Mesoporous silicas with chemically attached macrocyclic moieties were successfully prepared by sol-gel condensation of tetraethyl orthosilicate and β-cyclodextrin-silane in the presence of a structure-directing agent. Introduction of β-cyclodextrin groups into the silica framework was confirmed by the results of IR spectral, thermogravimetric, and quantitative chemical analysis of surface compounds. The porous structure of the obtained materials was characterized by nitrogen adsorption-desorption measurements, powder X-ray diffraction, transmission electron microscopy, and dynamic light scattering. It was found that the composition of the reaction mixture used in β-cyclodextrin-silane synthesis significantly affects the structural parameters of the resulting silicas. The increase in (3-aminopropyl)triethoxysilane as well as the coupling agent content in relation to β-cyclodextrin leads ultimately to the lowering or complete loss of hexagonal arrangement of pore channels in the synthesized materials. Formation of hexagonally ordered mesoporous structure was observed at molar composition of the mixture 0.049 TEOS:0.001 β-CD-silane:0.007 CTMAB:0.27 NH4OH:7.2 H2O and equimolar ratio of components in β-CD-silane synthesis. The sorption of alizarin yellow on starting silica and synthesized materials with chemically attached β-cyclodextrin moieties was studied in phosphate buffer solutions with pH 7.0. Experimental results of the dye equilibrium sorption were analyzed using Langmuir, Freundlich, and Redlich-Peterson isotherm models. It was proved that the Redlich-Peterson isotherm model is the most appropriate for fitting the equilibrium sorption of alizarin yellow on parent silica with hexagonally arranged mesoporous structure as well as on modified one with chemically immobilized β-cyclodextrin groups. [Figure not available: see fulltext.

Synthesis of Hierarchically Structured Hybrid Materials by Controlled Self-Assembly of Metal-Organic Framework with Mesoporous Silica for CO2 Adsorption.

PubMed

Chen, Chong; Li, Bingxue; Zhou, Lijin; Xia, Zefeng; Feng, Nengjie; Ding, Jing; Wang, Lei; Wan, Hui; Guan, Guofeng

2017-07-12

The HKUST-1@SBA-15 composites with hierarchical pore structure were constructed by in situ self-assembly of metal-organic framework (MOF) with mesoporous silica. The structure directing role of SBA-15 had an obvious impact on the growth of MOF crystals, which in turn affected the morphologies and structural properties of the composites. The pristine HKUST-1 and the composites with different content of SBA-15 were characterized by XRD, N 2 adsorption-desorption, SEM, TEM, FT-IR, TG, XPS, and CO 2 -TPD techniques. It was found that the composites were assembled by oriented growth of MOF nanocrystals on the surfaces of SBA-15 matrix. The interactions between surface silanol groups and metal centers induced structural changes and resulted in the increases in surface areas as well as micropore volumes of hybrid materials. Besides, the additional constraints from SBA-15 also restrained the expansion of HKUST-1, contributing to their smaller crystal sizes in the composites. The adsorption isotherms of CO 2 on the materials were measured and applied to calculate the isosteric heats of adsorption. The HS-1 composite exhibited an increase of 15.9% in CO 2 uptake capacity compared with that of HKUST-1. Moreover, its higher isosteric heats of CO 2 adsorption indicated the stronger interactions between the surfaces and CO 2 molecules. The adsorption rate of the composite was also improved due to the introduction of mesopores. Ten cycles of CO 2 adsorption-desorption experiments implied that the HS-1 had excellent reversibility of CO 2 adsorption. This study was intended to provide the possibility of assembling new composites with tailored properties based on MOF and mesoporous silica to satisfy the requirements of various applications.

An Overview of Recent Development in Composite Catalysts from Porous Materials for Various Reactions and Processes

PubMed Central

Xie, Zaiku; Liu, Zhicheng; Wang, Yangdong; Yang, Qihua; Xu, Longya; Ding, Weiping

2010-01-01

Catalysts are important to the chemical industry and environmental remediation due to their effective conversion of one chemical into another. Among them, composite catalysts have attracted continuous attention during the past decades. Nowadays, composite catalysts are being used more and more to meet the practical catalytic performance requirements in the chemical industry of high activity, high selectivity and good stability. In this paper, we reviewed our recent work on development of composite catalysts, mainly focusing on the composite catalysts obtained from porous materials such as zeolites, mesoporous materials, carbon nanotubes (CNT), etc. Six types of porous composite catalysts are discussed, including amorphous oxide modified zeolite composite catalysts, zeolite composites prepared by co-crystallization or overgrowth, hierarchical porous catalysts, host-guest porous composites, inorganic and organic mesoporous composite catalysts, and polymer/CNT composite catalysts. PMID:20559508

Bromocresol Green/Mesoporous Silica Adsorbent for Ammonia Gas Sensing via an Optical Sensing Instrument

PubMed Central

Chang, Yu-Chang; Bai, Hsunling; Li, Shou-Nan; Kuo, Chun-Nan

2011-01-01

A meso-structured Al-MCM-41 material was impregnated with bromocresol green (BG) dye and then incorporated into a UV-Vis DRA spectroscopic instrument for the online detection of ammonia gas. The absorption response of the Al-MCM-41/BG ammonia sensing material was very sensitive at the optical absorption wavelength of 630 nm. A high linear correlation was achieved for ppmv and sub-ppmv levels of ammonia gas. The response time for the quantitative detection of ammonia gas concentrations ranging from 0.25 to 2.0 ppmv was only a few minutes. The lower detection limit achieved was 0.185 ppmv. The color change process was fully reversible during tens of cycling tests. These features together make this mesoporous Al-MCM-41 material very promising for optical sensing applications. PMID:22163836

Tunable conductivity in mesoporous germanium

NASA Astrophysics Data System (ADS)

Beattie, Meghan N.; Bioud, Youcef A.; Hobson, David G.; Boucherif, Abderraouf; Valdivia, Christopher E.; Drouin, Dominique; Arès, Richard; Hinzer, Karin

2018-05-01

Germanium-based nanostructures have attracted increasing attention due to favourable electrical and optical properties, which are tunable on the nanoscale. High densities of germanium nanocrystals are synthesized via electrochemical etching, making porous germanium an appealing nanostructured material for a variety of applications. In this work, we have demonstrated highly tunable electrical conductivity in mesoporous germanium layers by conducting a systematic study varying crystallite size using thermal annealing, with experimental conductivities ranging from 0.6 to 33 (×10‑3) Ω‑1 cm‑1. The conductivity of as-prepared mesoporous germanium with 70% porosity and crystallite size between 4 and 10 nm is shown to be ∼0.9 × 10‑3 Ω‑1 cm‑1, 5 orders of magnitude smaller than that of bulk p-type germanium. Thermal annealing for 10 min at 400 °C further reduced the conductivity; however, annealing at 450 °C caused a morphological transformation from columnar crystallites to interconnecting granular crystallites and an increase in conductivity by two orders of magnitude relative to as-prepared mesoporous germanium caused by reduced influence of surface states. We developed an electrostatic model relating the carrier concentration and mobility of p-type mesoporous germanium to the nanoscale morphology. Correlation within an order of magnitude was found between modelled and experimental conductivities, limited by variation in sample uniformity and uncertainty in void size and fraction after annealing. Furthermore, theoretical results suggest that mesoporous germanium conductivity could be tuned over four orders of magnitude, leading to optimized hybrid devices.

Physical state of poorly water soluble therapeutic molecules loaded into SBA-15 ordered mesoporous silica carriers: a case study with itraconazole and ibuprofen.

PubMed

Mellaerts, Randy; Jammaer, Jasper A G; Van Speybroeck, Michiel; Chen, Hong; Van Humbeeck, Jan; Augustijns, Patrick; Van den Mooter, Guy; Martens, Johan A

2008-08-19

The ordered mesoporous silica material SBA-15 was loaded with the model drugs itraconazole and ibuprofen using three different procedures: (i) adsorption from solution, (ii) incipient wetness impregnation, and (iii) heating of a mixture of drug and SBA-15 powder. The location of the drug molecules in the SBA-15 particles and molecular interactions were investigated using nitrogen adsorption, TGA, DSC, DRS UV-vis, and XPS. The in vitro release of hydrophobic model drugs was evaluated in an aqueous environment simulating gastric fluid. The effectiveness of the loading method was found to be strongly compound dependent. Incipient wetness impregnation using a concentrated itraconazole solution in dichloromethane followed by solvent evaporation was most efficient for dispersing itraconazole in SBA-15. The itraconazole molecules were located on the mesopore walls and inside micropores of the mesopore walls. When SBA-15 was loaded by slurrying it in a diluted itraconazole solution from which the solvent was evaporated, the itraconazole molecules ended up in the mesopores that they plugged locally. At a loading of 30 wt %, itraconazole exhibited intermolecular interactions inside the mesopores revealed by UV spectroscopy and endothermic events traced with DSC. The physical mixing of itraconazole and SBA-15 powder followed by heating above the itraconazole melting temperature resulted in formulations in which glassy itraconazole particles were deposited externally on the SBA-15 particles. Loading with ibuprofen was successful with each of the three loading procedures. Ibuprofen preferably is positioned inside the micropores. In vitro release experiments showed fast release kinetics provided the drug molecules were evenly deposited over the mesoporous surface.

Preparation of highly ordered mesoporous Al2O3/TiO2 and its application in dye-sensitized solar cells.

PubMed

Kim, Jae-Yup; Kang, Soon Hyung; Kim, Hyun Sik; Sung, Yung-Eun

2010-02-16

Highly ordered mesoporous Al(2)O(3)/TiO(2) was prepared by sol-gel reaction and evaporation-induced self-assembly (EISA) for use in dye-sensitized solar cells. The prepared materials had two-dimensional, hexagonal pore structures with anatase crystalline phases. The average pore size of mesoporous Al(2)O(3)/TiO(2) remained uniform and in the range of 6.33-6.58 nm while the Brunauer-Emmett-Teller (BET) surface area varied from 181 to 212 m(2)/g with increasing the content of Al(2)O(3). The incorporation of Al content retarded crystallite growth, thereby decreasing crystallite size while simultaneously improving the uniformity of pore size and volume. The thin Al(2)O(3) layer was located mostly on the mesopore surface, as confirmed by X-ray photoelectron spectroscopy (XPS). The Al(2)O(3) coating on the mesoporous TiO(2) film contributes to the essential energy barrier which blocks the charge recombination process in dye-sensitized solar cells. Mesoporous Al(2)O(3)/TiO(2) (1 mol % Al(2)O(3)) exhibited enhanced power conversion efficiency (V(oc) = 0.74 V, J(sc) = 15.31 mA/cm(2), fill factor = 57%, efficiency = 6.50%) compared to pure mesoporous TiO(2) (V(oc) = 0.72 V, J(sc) = 16.03 mA/cm(2), fill factor = 51%, efficiency = 5.88%). Therefore, the power conversion efficiency was improved by approximately 10.5%. In particular, the increase in V(oc) and fill factor resulted from the inhibition of charge recombination and the improvement of pore structure.

Bimetallic Nanocatalysts in Mesoporous Silica for Hydrogen Production from Coal-Derived Fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuila, Debasish; Ilias, Shamsuddin

2013-02-13

In steam reforming reactions (SRRs) of alkanes and alcohols to produce H 2, noble metals such as platinum (Pt) and palladium (Pd) are extensively used as catalyst. These metals are expensive; so, to reduce noble-metal loading, bi-metallic nanocatalysts containing non-noble metals in MCM-41 (Mobil Composition of Material No. 41, a mesoporous material) as a support material with high-surface area were synthesized using one-pot hydrothermal procedure with a surfactant such as cetyltrimethylammonium bromide (CTAB) as a template. Bi-metallic nanocatalysts of Pd-Ni and Pd-Co with varying metal loadings in MCM-41 were characterized by x-ray diffraction (XRD), N 2 adsorption, and Transmission electronmore » microscopy (TEM) techniques. The BET surface area of MCM-41 (~1000 m 2/g) containing metal nanoparticles decreases with the increase in metal loading. The FTIR studies confirm strong interaction between Si-O-M (M = Pd, Ni, Co) units and successful inclusion of metal into the mesoporous silica matrix. The catalyst activities were examined in steam reforming of methanol (SRM) reactions to produce hydrogen. Reference tests using catalysts containing individual metals (Pd, Ni and Co) were also performed to investigate the effect of the bimetallic system on the catalytic behavior in the SRM reactions. The bimetallic system remarkably improves the hydrogen selectivity, methanol conversion and stability of the catalyst. The results are consistent with a synergistic behavior for the Pd-Ni-bimetallic system. The performance, durability and thermal stability of the Pd-Ni/MCM-41 and Pd-Co/MCM-41 suggest that these materials may be promising catalysts for hydrogen production from biofuels. A part of this work for synthesis and characterization of Pd-Ni-MCM-41 and its activity for SRM reactions has been published (“Development of Mesoporous Silica Encapsulated Pd-Ni Nanocatalyst for Hydrogen Production” in “Production and Purification of Ultraclean Transportation Fuels”; Hu, Y., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2011.)« less

Removal of malachite green dye from aqueous solution using mesoporous silica synthesized from 1-octyl-3-methylimidazolium chloride ionic liquid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ekka, Basanti; Nayak, Soumitra Ranjan; Dash, Priyabrat, E-mail: dashp@nitrkl.ac.in, E-mail: rkpatel@nitrkl.ac.in

2016-04-13

In this research, mesoporous silica was synthesized via a modified sol-gel route using 1-octyl-3-methylimidazolium chloride and was employed to remove malachite green (MG) dye from aqueous solution. Subsequently, this material was characterized and identified by different techniques such as Fourier transform infrared spectroscopy (FT-IR), N{sub 2} adsorption-desorption method, scanning electron microscopy (SEM), and thermosgravimetric analysis (TGA). Unique properties such as high surface area and pore diameter, in addition to highly reactive atoms and presence of various functional groups make the mesoporous silica possible for efficient removal of malachite green (MG). In batch experimental set-up, optimum conditions for quantitative removal ofmore » MG by mesoporous silica was attained by varying different variables such as adsorbent dosage, initial dye concentration, contact time, and pH. Optimum values were set as pH of 8.0, 0.5 g of adsorbent at contact time of 120 min. The adsorption of MG follows the pseudo-second-order rate equation. Equilibrium data fitted well with the Freundlich model at all amount of adsorbent, while maximum adsorption capacity was 5.981 mg g{sup −}1 for 0.5 g mesoporous silica synthesized in IL.« less

Surface functionalization of mesoporous silica SBA-15 by liquid-phase grafting of zirconium phosphate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Sheng; Hagaman, Edward; Ma, Zhen

2010-01-01

The introduction of mesoporous silicas in the 1990s has offered new opportunities for the engineering of ordered catalytic nanoreactors, but the acid properties of mesoporous silicas are rather poor. Herein, mesoporous silica (SBA-15) surfaces were functionalized by zirconium phosphate via two methods recently developed in our group. Zr(OPr){sub 4} and POCl{sub 3} were used as appropriate precursors in both methods. The main difference between these methods lies in whether Zr(OPr){sub 4} is grafted onto SBA-15 first and POCl{sub 3} second (method 1) or the grafting process takes place in one pot, with SBA-15, Zr(OPr){sub 4}, and POCl{sub 3} altogether (methodmore » 2). More zirconium phosphate could be grafted by repeating the above procedures. The materials were characterized by ICP-OES, XRD, N{sub 2} adsorption-desorption, TEM, {sup 31}P and {sup 29}Si MAS NMR, and NH{sub 3}-TPD, and their applications in catalytic isopropanol dehydration, cumene cracking, and metal-ion adsorption were demonstrated. Aluminum phosphate-modified SBA-15 samples could be obtained via these two methods as well. This work enriches the family of metal phosphate-functionalized mesoporous silicas as new solid acid catalysts.« less

Scalable 2D Mesoporous Silicon Nanosheets for High-Performance Lithium-Ion Battery Anode.

PubMed

Chen, Song; Chen, Zhuo; Xu, Xingyan; Cao, Chuanbao; Xia, Min; Luo, Yunjun

2018-03-01

Constructing unique mesoporous 2D Si nanostructures to shorten the lithium-ion diffusion pathway, facilitate interfacial charge transfer, and enlarge the electrode-electrolyte interface offers exciting opportunities in future high-performance lithium-ion batteries. However, simultaneous realization of 2D and mesoporous structures for Si material is quite difficult due to its non-van der Waals structure. Here, the coexistence of both mesoporous and 2D ultrathin nanosheets in the Si anodes and considerably high surface area (381.6 m 2 g -1 ) are successfully achieved by a scalable and cost-efficient method. After being encapsulated with the homogeneous carbon layer, the Si/C nanocomposite anodes achieve outstanding reversible capacity, high cycle stability, and excellent rate capability. In particular, the reversible capacity reaches 1072.2 mA h g -1 at 4 A g -1 even after 500 cycles. The obvious enhancements can be attributed to the synergistic effect between the unique 2D mesoporous nanostructure and carbon capsulation. Furthermore, full-cell evaluations indicate that the unique Si/C nanostructures have a great potential in the next-generation lithium-ion battery. These findings not only greatly improve the electrochemical performances of Si anode, but also shine some light on designing the unique nanomaterials for various energy devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CO₂ adsorption on amine-functionalized periodic mesoporous benzenesilicas.

PubMed

Sim, Kyohyun; Lee, Nakwon; Kim, Joonseok; Cho, Eun-Bum; Gunathilake, Chamila; Jaroniec, Mietek

2015-04-01

CO2 adsorption was investigated on amine-functionalized mesoporous silica (SBA-15) and periodic mesoporous organosilica (PMO) samples. Hexagonally (p6mm) ordered mesoporous SBA-15 and benzene-PMO (BPMO) samples were prepared in the presence of Pluronic P123 block copolymer template under acidic conditions. Three kinds of amine-containing organosilanes and polyethylenimine were used to functionalize SBA-15 and BPMO. Small-angle X-ray scattering and nitrogen adsorption isotherms showed that these samples featured ordered mesostructure, high surface area, and narrow pore size distributions. Solid-state (13)C- and (29)Si cross-polarization magic-angle spinning NMR spectra showed chemical linkage between amine-containing modifiers and the surface of mesoporous materials. The chemically linked amine-containing modifiers were found to be on both the inner and outer surfaces. N-[3-(trimethoxysilyl)propyl]ethylenediamine-modified BPMO (A2-BPMO) sample exhibited the highest CO2 uptake (i.e., ∼3.03 mmol/g measured on a volumetric adsorption analyzer) and the fastest adsorption rate (i.e., ∼13 min to attain 90% of the maximum amount) among all the samples studied. Selectivity and reproducibility measurements for the A2-BPMO sample showed quite good performance in flowing N2 gas at 40 mL/min and CO2 gas of 60 mL/min at 25 °C.

Porous Silicon—A Versatile Host Material

PubMed Central

Granitzer, Petra; Rumpf, Klemens

2010-01-01

This work reviews the use of porous silicon (PS) as a nanomaterial which is extensively investigated and utilized for various applications, e.g., in the fields of optics, sensor technology and biomedicine. Furthermore the combination of PS with one or more materials which are also nanostructured due to their deposition within the porous matrix is discussed. Such nanocompounds offer a broad avenue of new and interesting properties depending on the kind of involved materials as well as on their morphology. The filling of the pores performed by electroless or electrochemical deposition is described, whereas different morphologies, reaching from micro- to macro pores are utilized as host material which can be self-organized or fabricated by prestructuring. For metal-deposition within the porous structures, both ferromagnetic and non-magnetic metals are used. Emphasis will be put on self-arranged mesoporous silicon, offering a quasi-regular pore arrangement, employed as template for filling with ferromagnetic metals. By varying the deposition parameters the precipitation of the metal structures within the pores can be tuned in geometry and spatial distribution leading to samples with desired magnetic properties. The correlation between morphology and magnetic behaviour of such semiconducting/magnetic systems will be determined. Porous silicon and its combination with a variety of filling materials leads to nanocomposites with specific physical properties caused by the nanometric size and give rise to a multiplicity of potential applications in spintronics, magnetic and magneto-optic devices, nutritional food additives as well as drug delivery.

On the Synergistic Catalytic Properties of Bimetallic Mesoporous Materials Containing Aluminum and Zirconium: The Prins Cyclisation of Citronellal

PubMed Central

Telalović, Selvedin; Ramanathan, Anand; Ng, Jeck Fei; Maheswari, Rajamanickam; Kwakernaak, Cees; Soulimani, Fouad; Brouwer, Hans C; Chuah, Gaik Khuan; Weckhuysen, Bert M; Hanefeld, Ulf

2011-01-01

Bimetallic three-dimensional amorphous mesoporous materials, Al-Zr-TUD-1 materials, were synthesised by using a surfactant-free, one-pot procedure employing triethanolamine (TEA) as a complexing reagent. The amount of aluminium and zirconium was varied in order to study the effect of these metals on the Brønsted and Lewis acidity, as well as on the resulting catalytic activity of the material. The materials were characterised by various techniques, including elemental analysis, X-ray diffraction, high-resolution TEM, N2 physisorption, temperature-programmed desorption (TPD) of NH3, and 27Al MAS NMR, XPS and FT-IR spectroscopy using pyridine and CO as probe molecules. Al-Zr-TUD-1 materials are mesoporous with surface areas ranging from 700–900 m2 g−1, an average pore size of around 4 nm and a pore volume of around 0.70 cm3 g−1. The synthesised Al-Zr-TUD-1 materials were tested as catalyst materials in the Lewis acid catalysed Meerwein–Ponndorf–Verley reduction of 4-tert-butylcyclohexanone, the intermolecular Prins synthesis of nopol and in the intramolecular Prins cyclisation of citronellal. Although Al-Zr-TUD-1 catalysts possess a lower amount of acid sites than their monometallic counterparts, according to TPD of NH3, these materials outperformed those of the monometallic Al-TUD-1 as well as Zr-TUD-1 in the Prins cyclisation of citronellal. This proves the existence of synergistic properties of Al-Zr-TUD-1. Due to the intramolecular nature of the Prins cyclisation of citronellal, the hydrophilic surface of the catalyst as well as the presence of both Brønsted and Lewis acid sites synergy could be obtained with bimetallic Al-Zr-TUD-1. Besides spectroscopic investigation of the active sites of the catalyst material a thorough testing of the catalyst in different types of reactions is crucial in identifying its specific active sites. PMID:21259348

A multi-controlled drug delivery system based on magnetic mesoporous Fe3O4 nanopaticles and a phase change material for cancer thermo-chemotherapy

NASA Astrophysics Data System (ADS)

Zhang, Qi; Liu, Jian; Yuan, Kunjie; Zhang, Zhengguo; Zhang, Xiaowen; Fang, Xiaoming

2017-10-01

Herein a novel multi-controlled drug release system for doxorubicin (DOX) was developed, in which monodisperse mesoporous Fe3O4 nanoparticles were combined with a phase change material (PCM) and polyethylene glycol 2000 (PEG2000). It is found that the PCM/PEG/DOX mixture containing 20% PEG could be dissolved into water at 42 °C. The mesoporous Fe3O4 nanoparticles prepared by the solvothermal method had sizes of around 25 nm and exhibited a mesoporous microstructure. A simple solvent evaporation process was employed to load the PCM/PEG/DOX mixture on the mesoporous Fe3O4 nanoparticles completely. In the Fe3O4@PCM/PEG/DOX system, the pores of the Fe3O4 nanoparticles were observed to be filled with the mixture of PCM/PEG/DOX. The Fe3O4@PCM/PEG/DOX system showed a saturation magnetization value of 50.0 emu g-1, lower than 71.1 emu g-1 of the mesoporous Fe3O4 nanoparticles, but it was still high enough for magnetic targeting and hyperthermia application. The evaluation on drug release performance indicated that the Fe3O4@PCM/PEG/DOX system achieved nearly zero release of DOX in vitro in body temperature, while around 80% of DOX could be released within 1.5 h at the therapeutic threshold of 42 °C or under the NIR laser irradiation for about 4 h. And a very rapid release of DOX was achieved by this system when applying an alternating magnetic field. By comparing the systems with and without PEG2000, it is revealed that the presence of PEG2000 makes DOX easy to be released from 1-tetradecanol to water, owing to its functions of increasing the solubility of DOX in 1-tetradecanol as well as decreasing the surface tension between water and 1-tetradecanol. The novel drug release system shows great potential for the development of thermo-chemotherapy of cancer treatment.

Macroscopically Oriented Porous Materials with Periodic Ordered Structures: From Zeolites and Metal-Organic Frameworks to Liquid-Crystal-Templated Mesoporous Materials.

PubMed

Cho, Joonil; Ishida, Yasuhiro

2017-07-01

Porous materials with molecular-sized periodic structures, as exemplified by zeolites, metal-organic frameworks, or mesoporous silica, have attracted increasing attention due to their range of applications in storage, sensing, separation, and transformation of small molecules. Although the components of such porous materials have a tendency to pack in unidirectionally oriented periodic structures, such ideal types of packing cannot continue indefinitely, generally ceasing when they reach a micrometer scale. Consequently, most porous materials are composed of multiple randomly oriented domains, and overall behave as isotropic materials from a macroscopic viewpoint. However, if their channels could be unidirectionally oriented over a macroscopic scale, the resultant porous materials might serve as powerful tools for manipulating molecules. Guest molecules captured in macroscopically oriented channels would have their positions and directions well-defined, so that molecular events in the channels would proceed in a highly controlled manner. To realize such an ideal situation, numerous efforts have been made to develop various porous materials with macroscopically oriented channels. An overview of recent studies on the synthesis, properties, and applications of macroscopically oriented porous materials is presented. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation, characterization and application in deep catalytic ODS of the mesoporous silica pillared clay incorporated with phosphotungstic acid.

PubMed

Li, Baoshan; Liu, Zhenxing; Liu, Jianjun; Zhou, Zhiyuan; Gao, Xiaohui; Pang, Xinmei; Sheng, Huiting

2011-10-15

Mesoporous silica pillared clay (SPC) materials with different contents of H(3)PW(12)O(40) (HPW) heteropoly acid were synthesized by introducing HPW into clay interlayer template in an acidic suspension using sol-gel method. Samples with similar HPW loadings were also prepared by impregnation method using SPC as the support. The results of the characterizations showed that HPW was dispersed more homogeneously in the encapsulated samples than in the impregnated samples. The encapsulated materials exhibited better catalytic performance than the impregnated samples in oxidative desulfurization of dibenzothiophene-containing model oil. The sulfur removal reached up to 98.6% for the model oil under the experiential conditions. Copyright © 2011 Elsevier Inc. All rights reserved.

Catalytic performance of subtilisin immobilized without covalently attachment on surface-functionalized mesoporous silica materials

NASA Astrophysics Data System (ADS)

Murai, K.; Nonoyama, T.; Ando, F.; Kato, K.

2011-10-01

Mesoporous silica (MPS) materials were synthesized using cetyltrimethylammonium bromide or amphiphilic pluronic polymer P123 (EO20PO70EO20) as structure-directing agent. MPS samples were characterized by FE-SEM and N2 adsorption-desorption isotherms, respectively. Subtilisin from Bacillus licheiformis (4.1 × 7.8 × 3.7 nm) was easily immobilized by a direct one-step immobilization process onto MPS with different organo-functinalized surfaces. However, enzyme immobilized on MPS modified with 3-mercaptopropyl group strongly reduced its enantioselectivity. Denaturation temperature of immobilized subtilisin shifted to a high temperature compared to free-enzyme. These biocatalysts on MPS particles retained about 30% of original activity even after 5 cycles of recycle use.

Hierarchically porous Li3VO4/C nanocomposite as an advanced anode material for high-performance lithium-ion capacitors

NASA Astrophysics Data System (ADS)

Xu, Xuena; Niu, Feier; Zhang, Dapeng; Chu, Chenxiao; Wang, Chunsheng; Yang, Jian; Qian, Yitai

2018-04-01

Lithium-ion capacitors, as a hybrid electrochemical energy storage device, realize high specific energy and power density within one device, thus attracting extensive attention. Here, hierarchically porous Li3VO4/C nanocomposite is prepared by a solvo-thermal reaction, followed with a post-annealing process. This composite has macropores at the center and mesopores in the wall, thus effectively promoting electrolyte penetration and structure stability upon cycling simultaneously. Compared to mesoporous Li3VO4, the enhanced rate capability and specific capacity of hierarchically porous Li3VO4/C indicate the synergistic effect of mesopores and macropores. Inspired by these results, this composite is coupled with mesoporous carbon (CMK-3) for lithium-ion capacitors, generating a specific energy density of 105 Wh kg-1 at a power density of 188 W kg-1. Even if the power density increases to 9.3 kW kg-1, the energy density still remains 62 Wh kg-1. All these results demonstrate the promising potential of hierarchically porous Li3VO4 in lithium ion capacitors.

Preparation of nitrogen and sulfur co-doped ordered mesoporous carbon for enhanced microwave absorption performance

NASA Astrophysics Data System (ADS)

Yuan, Xiaoyan; Xue, Xingkun; Ma, Hailong; Guo, Shouwu; Cheng, Laifei

2017-09-01

Ordered mesoporous carbon nanomaterials (OMCs) co-doped with homogeneous nitrogen and sulfur heteroatoms were prepared by nanocasting with the pyrrole oligomer catalyzed by sulfuric acid as a precursor and ordered mesoporous silica SBA-15 as a hard-template. By multi-technique approach utilization, it was demonstrated that the N and S co-doped OMCs possessed high ordered mesoporous structures, large surface areas and homogeneous distribution of heteroatoms. As a microwave absorber, the as-prepared materials exhibited a minimum reflection loss (RL) of -32.5 dB at the thickness of 2.5 mm and an absorption bandwidth of 3.2 GHz (RL < -10 dB) in X-band (8.2-12.4 GHz). The good microwave absorption performance was mainly originated from the high electrical conductivity induced by the high surface activity and special structures. And microwave energy can be effectively attenuated through multiple reflections and absorptions in complex conductive network. The design strategy in this work would contribute to the production of a lightweight absorber, presenting a strong absorbency and a wide bandwidth in microwave frequency.

"Egg-Box"-Assisted Fabrication of Porous Carbon with Small Mesopores for High-Rate Electric Double Layer Capacitors.

PubMed

Kang, Danmiao; Liu, Qinglei; Gu, Jiajun; Su, Yishi; Zhang, Wang; Zhang, Di

2015-11-24

Here we report a method to fabricate porous carbon with small mesopores around 2-4 nm by simple activation of charcoals derived from carbonization of seaweed consisting of microcrystalline domains formed by the "egg-box" model. The existence of mesopores in charcoals leads to a high specific surface area up to 3270 m(2) g(-1), with 95% surface area provided by small mesopores. This special pore structure shows high adaptability when used as electrode materials for an electric double layer capacitor, especially at high charge-discharge rate. The gravimetric capacitance values of the porous carbon are 425 and 210 F g(-1) and volumetric capacitance values are 242 and 120 F cm(-3) in 1 M H2SO4 and 1 M TEA BF4/AN, respectively. The capacitances even remain at 280 F g(-1) (160 F cm(-3)) at 100 A g(-1) and 156 F g(-1) (90 F cm(-3)) at 50 A g(-1) in the aqueous and organic electrolytes, demonstrating excellent high-rate capacitive performance.

Nanostructured mesoporous silica: new perspectives for fighting antimicrobial resistance

NASA Astrophysics Data System (ADS)

Voicu, Georgeta; Dogaru, Ionuţ; Meliţă, Daniela; Meştercă, Raluca; Spirescu, Vera; Stan, Eliza; Tote, Eliza; Mogoantă, Laurenţiu; Mogoşanu, George Dan; Grumezescu, Alexandru Mihai; Truşcă, Roxana; Vasile, Eugeniu; Iordache, Florin; Chifiriuc, Mariana-Carmen; Holban, Alina Maria

2015-05-01

This paper investigates the antimicrobial potential of nanostructured mesoporous silica (NMS) functionalized with essential oils (EOs) and antibiotics (ATBs). The NMS networks were obtained by the basic procedure from cetyltrimethylammonium bromide and tetraethyl orthosilicate in the form of granules with diameters ranging from 100 to 300 nm with an average pore diameter of 2.2 nm, as confirmed by the BET-TEM analyses. The Salvia officinalis (SO) and Coriandrum sativum (CS) EOs and the streptomycin and neomycin ATBs were loaded in the NMS pores. TG analysis was performed in order to estimate the amount of the entrapped volatile EOs. The results of the biological analyses revealed that NMS/SO and NMS/CS exhibited a very good antimicrobial activity to an extent comparable or even superior to the one triggered by ATB, and a good in vitro and in vivo biocompatibility. Due to their regular pores, high biocompatibility, antimicrobial activity, and capacity to stabilize the volatile EOs, the obtained NMS can be used as an efficient drug delivery system for further biomedical applications.

Discovery of abnormal lithium-storage sites in molybdenum dioxide electrodes

PubMed Central

Shon, Jeong Kuk; Lee, Hyo Sug; Park, Gwi Ok; Yoon, Jeongbae; Park, Eunjun; Park, Gyeong Su; Kong, Soo Sung; Jin, Mingshi; Choi, Jae-Man; Chang, Hyuk; Doo, Seokgwang; Kim, Ji Man; Yoon, Won-Sub; Pak, Chanho; Kim, Hansu; Stucky, Galen D.

2016-01-01

Developing electrode materials with high-energy densities is important for the development of lithium-ion batteries. Here, we demonstrate a mesoporous molybdenum dioxide material with abnormal lithium-storage sites, which exhibits a discharge capacity of 1,814 mAh g−1 for the first cycle, more than twice its theoretical value, and maintains its initial capacity after 50 cycles. Contrary to previous reports, we find that a mechanism for the high and reversible lithium-storage capacity of the mesoporous molybdenum dioxide electrode is not based on a conversion reaction. Insight into the electrochemical results, obtained by in situ X-ray absorption, scanning transmission electron microscopy analysis combined with electron energy loss spectroscopy and computational modelling indicates that the nanoscale pore engineering of this transition metal oxide enables an unexpected electrochemical mass storage reaction mechanism, and may provide a strategy for the design of cation storage materials for battery systems. PMID:27001935

Tunneled Mesoporous Carbon Nanofibers with Embedded ZnO Nanoparticles for Ultrafast Lithium Storage.

PubMed

An, Geon-Hyoung; Lee, Do-Young; Ahn, Hyo-Jin

2017-04-12

Carbon and metal oxide composites have received considerable attention as anode materials for Li-ion batteries (LIBs) owing to their excellent cycling stability and high specific capacity based on the chemical and physical stability of carbon and the high theoretical specific capacity of metal oxides. However, efforts to obtain ultrafast cycling stability in carbon and metal oxide composites at high current density for practical applications still face important challenges because of the longer Li-ion diffusion pathway, which leads to poor ultrafast performance during cycling. Here, tunneled mesoporous carbon nanofibers with embedded ZnO nanoparticles (TMCNF/ZnO) are synthesized by electrospinning, carbonization, and postcalcination. The optimized TMCNF/ZnO shows improved electrochemical performance, delivering outstanding ultrafast cycling stability, indicating a higher specific capacity than previously reported ZnO-based anode materials in LIBs. Therefore, the unique architecture of TMCNF/ZnO has potential for use as an anode material in ultrafast LIBs.

Fabrication of Co3O4 mesoporous thin films by using cobalt/chitosan precursor on fluorine-doped tin oxide glass

NASA Astrophysics Data System (ADS)

Yang, Hui-Chia; Tsai, Jung-Che

2017-06-01

For the development of high-performance and low-cost electrode materials, many alternative materials have been fabricated by various groups. Among these materials, Co3O4 has been demonstrated to be a promising candidate for pseudocapacitors because of its low potential environmental pollution, low cost, and extremely high theoretical specific capacitance. Chitosan, a linear polysaccharide produced by the deacetylation of chitin, is a nontoxic, tissue-compatible polymeric biomaterial. It is usually used to eliminate or filter the heavy metals in wastewater. That is, chitosan can act as a deliverer of metal ions and a nanostructure constructer of metals (or metal oxides). In this study, a facile approach is developed to synthesize mesoporous cobalt oxide thin films on fluorine-doped tin oxide (FTO)-coated glass with environmentally friendly chitosan, which chelates cobalt ions.

Aqueous gating of van der Waals materials on bilayer nanopaper.

PubMed

Bao, Wenzhong; Fang, Zhiqiang; Wan, Jiayu; Dai, Jiaqi; Zhu, Hongli; Han, Xiaogang; Yang, Xiaofeng; Preston, Colin; Hu, Liangbing

2014-10-28

In this work, we report transistors made of van der Waals materials on a mesoporous paper with a smooth nanoscale surface. The aqueous transistor has a novel planar structure with source, drain, and gate electrodes on the same surface of the paper, while the mesoporous paper is used as an electrolyte reservoir. These transistors are enabled by an all-cellulose paper with nanofibrillated cellulose (NFC) on the top surface that leads to an excellent surface smoothness, while the rest of the microsized cellulose fibers can absorb electrolyte effectively. Based on two-dimensional van der Waals materials, including MoS2 and graphene, we demonstrate high-performance transistors with a large on-off ratio and low subthreshold swing. Such planar transistors with absorbed electrolyte gating can be used as sensors integrated with other components to form paper microfluidic systems. This study is significant for future paper-based electronics and biosensors.

Noninvasive remote-controlled release of drug molecules in vitro using magnetic actuation of mechanized nanoparticles.

PubMed

Thomas, Courtney R; Ferris, Daniel P; Lee, Jae-Hyun; Choi, Eunjoo; Cho, Mi Hyeon; Kim, Eun Sook; Stoddart, J Fraser; Shin, Jeon-Soo; Cheon, Jinwoo; Zink, Jeffrey I

2010-08-11

Mesoporous silica nanoparticles are useful nanomaterials that have demonstrated the ability to contain and release cargos with mediation by gatekeepers. Magnetic nanocrystals have the ability to exhibit hyperthermic effects when placed in an oscillating magnetic field. In a system combining these two materials and a thermally sensitive gatekeeper, a unique drug delivery system can be produced. A novel material that incorporates zinc-doped iron oxide nanocrystals within a mesoporous silica framework that has been surface-modified with pseudorotaxanes is described. Upon application of an AC magnetic field, the nanocrystals generate local internal heating, causing the molecular machines to disassemble and allowing the cargos (drugs) to be released. When breast cancer cells (MDA-MB-231) were treated with doxorubicin-loaded particles and exposed to an AC field, cell death occurred. This material promises to be a noninvasive, externally controlled drug delivery system with cancer-killing properties.

Micro-mesoporous carbon spheres derived from carrageenan as electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Fan, Yang; Yang, Xin; Zhu, Bing; Liu, Pei-Fang; Lu, Hai-Ting

2014-12-01

The polysaccharide carrageenan is used as a natural precursor to prepare micro-mesoporous carbon spheres. The carbon spheres were synthesized by hydrothermal carbonization of carrageenan, and subsequent chemical activation by KOH at different temperatures. The obtained micro-mesoporous carbon spheres have high surface area (up to 2502 m2 g-1) and large pore volume (up to 1.43 cm3 g-1). Moreover, the micro- and mesoporosity can be finely tuned be modifying the activation temperatures in the range of 700-900 °C. The carbon spheres activated at 900 °C present high specific capacitance of 230 F g-1 at a current density of 1 A g-1 and good ion transport kinetics. The good capacitive performance can be ascribed to the high specific surface area, well-controlled micro- and mesoporosity and narrow pore size distribution.

The effect of the distance between acidic site and basic site immobilized on mesoporous solid on the activity in catalyzing aldol condensation

NASA Astrophysics Data System (ADS)

Yu, Xiaofang; Yu, Xiaobo; Wu, Shujie; Liu, Bo; Liu, Heng; Guan, Jingqi; Kan, Qiubin

2011-02-01

Acid-base bifunctional heterogeneous catalysts containing carboxylic and amine groups, which were immobilized at defined distance from one another on the mesoporous solid were synthesized by immobilizing lysine onto carboxyl-SBA-15. The obtained materials were characterized by X-ray diffraction (XRD), N 2 adsorption, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron micrographs (SEM), transmission electron micrographs (TEM), elemental analysis, and back titration. Proximal-C-A-SBA-15 with a proximal acid-base distance was more active than maximum-C-A-SBA-15 with a maximum acid-base distance in aldol condensation reaction between acetone and various aldehydes. It appears that the distance between acidic site and basic site immobilized on mesoporous solid should be an essential factor for catalysis optimization.

Metal-nitrogen doping of mesoporous carbon/graphene nanosheets by self-templating for oxygen reduction electrocatalysts.

PubMed

Li, Shuang; Wu, Dongqing; Liang, Haiwei; Wang, Jinzuan; Zhuang, Xiaodong; Mai, Yiyong; Su, Yuezeng; Feng, Xinliang

2014-11-01

We demonstrate a general and efficient self-templating strategy towards transition metal-nitrogen containing mesoporous carbon/graphene nanosheets with a unique two-dimensional (2D) morphology and tunable mesoscale porosity. Owing to the well-defined 2D morphology, nanometer-scale thickness, high specific surface area, and the simultaneous doping of the metal-nitrogen compounds, the as-prepared catalysts exhibits excellent electrocatalytic activity and stability towards the oxygen reduction reaction (ORR) in both alkaline and acidic media. More importantly, such a self-templating approach towards two-dimensional porous carbon hybrids with diverse metal-nitrogen doping opens up new avenues to mesoporous heteroatom-doped carbon materials as electrochemical catalysts for oxygen reduction and hydrogen evolution, with promising applications in fuel cell and battery technologies. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultralight mesoporous magnetic frameworks by interfacial assembly of Prussian blue nanocubes.

PubMed

Kong, Biao; Tang, Jing; Wu, Zhangxiong; Wei, Jing; Wu, Hao; Wang, Yongcheng; Zheng, Gengfeng; Zhao, Dongyuan

2014-03-10

A facile approach for the synthesis of ultralight iron oxide hierarchical structures with tailorable macro- and mesoporosity is reported. This method entails the growth of porous Prussian blue (PB) single crystals on the surface of a polyurethane sponge, followed by in situ thermal conversion of PB crystals into three-dimensional mesoporous iron oxide (3DMI) architectures. Compared to previously reported ultralight materials, the 3DMI architectures possess hierarchical macro- and mesoporous frameworks with multiple advantageous features, including high surface area (ca. 117 m(2) g(-1)) and ultralow density (6-11 mg cm(-3)). Furthermore, they can be synthesized on a kilogram scale. More importantly, these 3DMI structures exhibit superparamagnetism and tunable hydrophilicity/hydrophobicity, thus allowing for efficient multiphase interfacial adsorption and fast multiphase catalysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Graded porous inorganic materials derived from self-assembled block copolymer templates.

PubMed

Gu, Yibei; Werner, Jörg G; Dorin, Rachel M; Robbins, Spencer W; Wiesner, Ulrich

2015-03-19

Graded porous inorganic materials directed by macromolecular self-assembly are expected to offer unique structural platforms relative to conventional porous inorganic materials. Their preparation to date remains a challenge, however, based on the sparsity of viable synthetic self-assembly pathways to control structural asymmetry. Here we demonstrate the fabrication of graded porous carbon, metal, and metal oxide film structures from self-assembled block copolymer templates by using various backfilling techniques in combination with thermal treatments for template removal and chemical transformations. The asymmetric inorganic structures display mesopores in the film top layers and a gradual pore size increase along the film normal in the macroporous sponge-like support structure. Substructure walls between macropores are themselves mesoporous, constituting a structural hierarchy in addition to the pore gradation. Final graded structures can be tailored by tuning casting conditions of self-assembled templates as well as the backfilling processes. We expect that these graded porous inorganic materials may find use in applications including separation, catalysis, biomedical implants, and energy conversion and storage.

Synthesis, characterization, and catalytic application of ordered mesoporous carbon–niobium oxide composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Juan-Li; Gao, Shuang; Liu, Chun-Ling

2014-11-15

Graphical abstract: The ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process. - Highlights: • Ordered mesoporous carbon–niobium oxide composites were synthesized. • The content of Nb{sub 2}O{sub 5} in the composites could be tuned from 38 to 75%. • Niobium species were highly dispersed in amorphous carbon framework walls. • The composites exhibited good catalytic performance in the dehydration of fructose. - Abstract: Ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process using phenolic resol as carbon source, niobium chloride asmore » precursor and amphiphilic triblock copolymer Pluronic F127 as template. The resulting materials were characterized using a combination of techniques including differential scanning calorimetry–thermogravimetric analysis, N{sub 2} physical adsorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results show that with increasing the content of Nb{sub 2}O{sub 5} from 38 to 75% the specific surface area decreases from 306.4 to 124.5 m{sup 2} g{sup −1}, while the ordered mesoporous structure is remained. Niobium species is well dispersed in the amorphous carbon framework. The mesoporous carbon–niobium oxide composites exhibit high catalytic activity in the dehydration of fructose to 5-hydroxymethylfurfural. A 100% conversion of fructose and a 76.5% selectivity of 5-hydroxymethylfurfural were obtained over the carbon–niobium oxide composite containing 75% Nb{sub 2}O{sub 5} under the investigated reaction conditions.« less

Self-assembled mesoporous Co and Ni-ferrite spherical clusters consisting of spinel nanocrystals prepared using a template-free approach.

PubMed

Yu, Byong Yong; Kwak, Seung-Yeop

2011-10-21

Based on a self-assembly strategy, spherical mesoporous cobalt and nickel ferrite nanocrystal clusters with a large surface area and narrow size distribution were successfully synthesized for the first time via a template-free solvothermal process in ethylene glycol and subsequent heat treatment. In this work, the mesopores in the ferrite clusters were derived mainly from interior voids between aggregated primary nanoparticles (with crystallite size of less than 7 nm) and disordered particle packing domains. The concentration of sodium acetate is shown herein to play a crucial role in the formation of mesoporous ferrite spherical clusters. These ferrite clusters were characterized in detail using wide-angle X-ray diffraction, thermogravimetric-differential thermal analysis, (57)Fe Mössbauer spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, standard and high-resolution transmission electron microscopy, and other techniques. The results confirmed the formation of both pure-phase ferrite clusters with highly crystalline spinel structure, uniform size (about 160 nm) and spherical morphology, and worm-like mesopore structures. The BET specific surface areas and mean pore sizes of the mesoporous Co and Ni-ferrite clusters were as high as 160 m(2) g(-1) and 182 m(2) g(-1), and 7.91 nm and 6.87 nm, respectively. A model for the formation of the spherical clusters in our system is proposed on the basis of the results. The magnetic properties of both samples were investigated at 300 K, and it was found that these materials are superparamagnetic. This journal is © The Royal Society of Chemistry 2011

Preparation and Characterization of Mesoporous Zirconia Made by Using a Poly (methyl methacrylate) Template

NASA Astrophysics Data System (ADS)

Duan, Guorong; Zhang, Chunxiang; Li, Aimei; Yang, Xujie; Lu, Lude; Wang, Xin

2008-03-01

Superfine powders of poly (methyl methacrylate) (PMMA) have been prepared by means of an emulsion polymerization method. These have been used as templates in the synthesis of tetragonal phase mesoporous zirconia by the sol gel method, using zirconium oxychloride and oxalic acid as raw materials. The products have been characterized by infrared spectroscopy, X-ray diffraction analysis, transmission electron microscopy, N2 adsorption-desorption isotherms, and pore size distribution. The results indicate that the average pore size was found to be 3.7 nm.

Mesoporous silicon synthesis and applications in Li-ion batteries and solar hydrogen fuel cells

DOEpatents

Wang, Donghai; Dai, Fang; Yi, Ran; Zai, Jianto

2017-05-23

We provide a mesoporous silicon material (PSi) prepared via a template-free and HF-free process. The production process is facile and scalable, and it may be conducted under mild reaction conditions. The silicon may be produced directly by the reduction of a silicon-halogenide precursor (for example, SiCl.sub.4) with an alkaline alloy (for example, NaK alloy). The resulting Si-salt matrix is then annealed for the pore formation and crystallite growth. Final product is obtained by removal of the salt by-products with water.

Preparation of resveratrol-loaded nanoporous silica materials with different structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Popova, Margarita, E-mail: mpopova@orgchem.bas.bg; Szegedi, Agnes; Mavrodinova, Vesselina

2014-11-15

Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated.more » Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound. - Graphical abstract: trans-Resveratrol was stabilized in the pores of BEA zeolite, MCM-41and KIL2 mesoporous silicas. - Highlights: • BEA, KIL-2 and MCM-41 materials were used as carriers for resveratrol loading. • Resveratrol encapsulation in ethanol solution and solid state procedure were applied. • The solid-state preparation appears very effective for stabilization of trans-resveratrol.« less

Synthesis Mechanism and Thermal Optimization of an Economical Mesoporous Material Using Silica: Implications for the Effective Removal or Delivery of Ibuprofen

PubMed Central

Kittappa, Shanmuga; Cui, Mingcan; Ramalingam, Malarvili; Ibrahim, Shaliza; Khim, Jeehyeong; Yoon, Yeomin; Snyder, Shane A.; Jang, Min

2015-01-01

Mesoporous silica materials (MSMs) were synthesized economically using silica (SiO2) as a precursor via a modified alkaline fusion method. The MSM prepared at 500°C (MSM–500) had the highest surface area, pore size, and volume, and the results of isotherms and the kinetics of ibuprofen (IBP) removal indicated that MSM–500 had the highest sorption capacity and fastest removal speed vs. SBA–15 and zeolite. Compared with commercial granular activated carbon (GAC), MSM–500 had a ~100 times higher sorption rate at neutral pH. IBP uptake by MSM–500 was thermodynamically favorable at room temperature, which was interpreted as indicating relatively weak bonding because the entropy (∆adsS, –0.07 J mol–1 K–1) was much smaller. Five times recycling tests revealed that MSM–500 had 83–87% recovery efficiencies and slower uptake speeds due to slight deformation of the outer pore structure. In the IBP delivery test, MSM–500 drug loading was 41%, higher than the reported value of SBA–15 (31%). The in vitro release of IBP was faster, almost 100%, reaching equilibrium within a few hours, indicating its effective loading and unloading characteristics. A cost analysis study revealed that the MSM was ~10–70 times cheaper than any other mesoporous silica material for the removal or delivery of IBP. PMID:26161510

Electrochemical studies of mesoporous and copper-modified mesoporous TiO2 -anode material

NASA Astrophysics Data System (ADS)

Ajay Kumar, R.; Venkateswara Rao, A.; Rajesh, Ch.

2018-05-01

Herein, we developed a method to synthesize highly ordered mesoporous TiO2 (MT) and copper-modified M- TiO2 (CMT) with a high surface area by the hydrothermal method using Pluronic P-123 as a surfactant at 150 ° C. CMT with different copper concentrations (0.1, 0.2 and 0.3%) was synthesized. The structural characterization studies revealed that MT and CMT particles are in anatase phase. The average particle size was found to be 24± 0.8 nm for MT and that of CMT was 25± 0.6 , 27± 0.4 and 28± 0.3 nm, respectively. The presence of ordered spherical MT and CMT particles with uniform size distribution was confirmed by performing morphological studies using FE-SEM. Optical absorption studies indicate the presence of copper because of the red shift in the band gap and also a broad peak around 800nm when compared with MT. EIS studies point out an increase in conductivity from MT through 0.3% CMT by a decrease in the charge transfer resistance. Further, charge-discharge studies were carried on this material at room temperature for lithium-ion battery applications. CMT with 0.3% copper showed high initial discharge capacity and better cyclability. The results indicate that this material can act as a promising negative electrode.

Enzymes immobilized in mesoporous silica: a physical-chemical perspective.

PubMed

Carlsson, Nils; Gustafsson, Hanna; Thörn, Christian; Olsson, Lisbeth; Holmberg, Krister; Åkerman, Björn

2014-03-01

Mesoporous materials as support for immobilized enzymes have been explored extensively during the last two decades, primarily not only for biocatalysis applications, but also for biosensing, biofuels and enzyme-controlled drug delivery. The activity of the immobilized enzymes inside the pores is often different compared to that of the free enzymes, and an important challenge is to understand how the immobilization affects the enzymes in order to design immobilization conditions that lead to optimal enzyme activity. This review summarizes methods that can be used to understand how material properties can be linked to changes in enzyme activity. Real-time monitoring of the immobilization process and techniques that demonstrate that the enzymes are located inside the pores is discussed by contrasting them to the common practice of indirectly measuring the depletion of the protein concentration or enzyme activity in the surrounding bulk phase. We propose that pore filling (pore volume fraction occupied by proteins) is the best standard for comparing the amount of immobilized enzymes at the molecular level, and present equations to calculate pore filling from the more commonly reported immobilized mass. Methods to detect changes in enzyme structure upon immobilization and to study the microenvironment inside the pores are discussed in detail. Combining the knowledge generated from these methodologies should aid in rationally designing biocatalyst based on enzymes immobilized in mesoporous materials. © 2013 Elsevier B.V. All rights reserved.

A mesoporous carbon–sulfur composite as cathode material for high rate lithium sulfur batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Hyunji; Zhao, Xiaohui; Kim, Dul-Sun

2014-10-15

Highlights: • CMK-3 mesoporous carbon was synthesized as conducting reservoir for housing sulfur. • Sulfur/CMK-3 composites were prepared by two-stage thermal treatment. • The composite at 300 °C for 20 h shows improved electrochemical properties. - Abstract: Sulfur composite was prepared by encapsulating sulfur into CMK-3 mesoporous carbon with different heating times and then used as the cathode material for lithium sulfur batteries. Thermal treatment at 300 °C plays an important role in the sulfur encapsulation process. With 20 h of heating time, a portion of sulfur remained on the surface of carbon, whereas with 60 h of heating time,more » sulfur is confined deeply in the small pores of carbon that cannot be fully exploited in the redox reaction, thus causing low capacity. The S/CMK-3 composite with thermal treatment for 40 h at 300 °C contained 51.3 wt.% sulfur and delivered a high initial capacity of 1375 mA h g{sup −1} at 0.1 C. Moreover, it showed good capacity retention of 704 mA h g{sup −1} at 0.1 C and 578 mA h g{sup −1} at 2 C even after 100 cycles, which proves its potential as a cathode material for high capability lithium sulfur batteries.« less

Understanding Diffusion in Hierarchical Zeolites with House-of-Cards Nanosheets.

PubMed

Bai, Peng; Haldoupis, Emmanuel; Dauenhauer, Paul J; Tsapatsis, Michael; Siepmann, J Ilja

2016-08-23

Introducing mesoporosity to conventional microporous sorbents or catalysts is often proposed as a solution to enhance their mass transport rates. Here, we show that diffusion in these hierarchical materials is more complex and exhibits non-monotonic dependence on sorbate loading. Our atomistic simulations of n-hexane in a model system containing microporous nanosheets and mesopore channels indicate that diffusivity can be smaller than in a conventional zeolite with the same micropore structure, and this observation holds true even if we confine the analysis to molecules completely inside the microporous nanosheets. Only at high sorbate loadings or elevated temperatures, when the mesopores begin to be sufficiently populated, does the overall diffusion in the hierarchical material exceed that in conventional microporous zeolites. Our model system is free of structural defects, such as pore blocking or surface disorder, that are typically invoked to explain slower-than-expected diffusion phenomena in experimental measurements. Examination of free energy profiles and visualization of molecular diffusion pathways demonstrates that the large free energy cost (mostly enthalpic in origin) for escaping from the microporous region into the mesopores leads to more tortuous diffusion paths and causes this unusual transport behavior in hierarchical nanoporous materials. This knowledge allows us to re-examine zero-length-column chromatography data and show that these experimental measurements are consistent with the simulation data when the crystallite size instead of the nanosheet thickness is used for the nominal diffusional length.

Adsorption of caffeine on mesoporous activated carbon fibers prepared from pineapple plant leaves.

PubMed

Beltrame, Karla K; Cazetta, André L; de Souza, Patrícia S C; Spessato, Lucas; Silva, Taís L; Almeida, Vitor C

2018-01-01

The present work reports the preparation of activated carbon fibers (ACFs) from pineapple plant leaves, and its application on caffeine (CFN) removal from aqueous solution. The preparation procedure was carried out using the H 3 PO 4 as activating agent and slow pyrolysis under N 2 atmosphere. The characterization of materials was performed from the N 2 adsorption and desorption isotherms, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectroscopy, Boehm titration and pH pzc method. ACFs showed high BET surface area value (S BET = 1031m 2 g -1 ), well-developed mesoporous structure (mesopore volume of 1.27cm³ g -1 ) and pores with average diameter (D M ) of 5.87nm. Additionally, ACFs showed features of fibrous material with predominance of acid groups on its surface. Adsorption studies indicated that the pseudo-second order kinetic and Langmuir isotherm models were that best fitted to the experimental data. The monolayer adsorption capacity was found to be 155.50mgg -1 . thermodynamic studies revealed that adsorption process is spontaneous, exothermic and occurs preferably via physisorption. The pineapple leaves are an efficient precursor for preparation of ACFs, which were successful applied as adsorbent material for removal of caffeine from the aqueous solutions. Copyright © 2017 Elsevier Inc. All rights reserved.

MoO2-ordered mesoporous carbon nanocomposite as an anode material for lithium-ion batteries.

PubMed

Zeng, Lingxing; Zheng, Cheng; Deng, Cuilin; Ding, Xiaokun; Wei, Mingdeng

2013-03-01

In the present work, the nanocomposite of MoO2-ordered mesoporous carbon (MoO2-OMC) was synthesized for the first time using a carbon thermal reduction route and the mesoporous carbon as the nanoreactor. The synthesized nanocomposite was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), N2 adsorption-desorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) measurements. Furthermore, this nanocomposite was used as an anode material for Li-ion intercalation and exhibited large reversible capacity, high rate performance, and good cycling stability. For instance, a high reversible capacity of 689 mAh g(-1) can remain after 50 cycles at a current density of 50 mA g(-1). It is worth mentioning that the MoO2-OMC nanocomposite electrode can attain a high reversible capacity of 401 mAh g(-1) at a current density as high as 2 A g(-1). These results might be due to the intrinsic characteristics of nanocomposite, which offered a better accommodation of the strain and volume changes and a shorter path for Li-ion and electron transport, leading to the improved capacity and enhanced rate capability.

Preparation and CO 2 adsorption properties of soft-templated mesoporous carbons derived from chestnut tannin precursors

DOE PAGES

Nelson, Kimberly M.; Mahurin, Shannon Mark; Mayes, Richard T.; ...

2015-10-09

This paper presents a soft templating approach for mesoporous carbon using the polyphenolic heterogeneous biomass, chestnut tannin, as the carbon precursor. By varying synthesis parameters such as tannin:surfactant ratio, cross-linker, reaction time and acid catalyst, the pore structure could be controllably modulated from lamellar to a more ordered hexagonal array. Carbonization at 600 °C under nitrogen produced a bimodal micro-mesoporous carbonaceous material exhibiting enhanced hydrogen bonding with the soft template, similar to that shown by soft-templating of phenolic-formaldehyde resins, allowing for a tailorable pore size. By utilizing the acidic nature of chestnut tannin (i.e. gallic and ellagic acid), hexagonal-type mesostructuresmore » were formed without the use of an acid catalyst. The porous carbon materials were activated with ammonia to increase the available surface area and incorporate nitrogen-containing functionality which led to a maximum CO 2 adsorption capacity at 1 bar of 3.44 mmol/g and 2.27 mmol/g at 0 °C and 25 °C, respectively. The ammonia-activated carbon exhibited multiple peaks in the adsorption energy distribution which indicates heterogeneity of adsorption sites for CO 2 capture.« less

Mesoporous nanostructured Nb-doped titanium dioxide microsphere catalyst supports for PEM fuel cell electrodes.

PubMed

Chevallier, Laure; Bauer, Alexander; Cavaliere, Sara; Hui, Rob; Rozière, Jacques; Jones, Deborah J

2012-03-01

Crystalline microspheres of Nb-doped TiO(2) with a high specific surface area were synthesized using a templating method exploiting ionic interactions between nascent inorganic components and an ionomer template. The microspheres exhibit a porosity gradient, with a meso-macroporous kernel, and a mesoporous shell. The material has been investigated as cathode electrocatalyst support for polymer electrolyte membrane (PEM) fuel cells. A uniform dispersion of Pt particles on the Nb-doped TiO(2) support was obtained using a microwave method, and the electrochemical properties assessed by cyclic voltammetry. Nb-TiO(2) supported Pt demonstrated very high stability, as after 1000 voltammetric cycles, 85% of the electroactive Pt area remained compared to 47% in the case of commercial Pt on carbon. For the oxygen reduction reaction (ORR), which takes place at the cathode, the highest stability was again obtained with the Nb-doped titania-based material even though the mass activity calculated at 0.9 V vs RHE was slightly lower. The microspherical structured and mesoporous Nb-doped TiO(2) is an alternative support to carbon for PEM fuel cells. © 2012 American Chemical Society

Gold recovery from low concentrations using nanoporous silica adsorbent

NASA Astrophysics Data System (ADS)

Aledresse, Adil

The development of high capacity adsorbents with uniform porosity denoted 5%MP-HMS (5% Mercaptopropyl-Hexagonal Mesoporous Structure) to extract gold from noncyanide solutions is presented. The preliminary studies from laboratory simulated noncyanide gold solutions show that the adsorption capacities of these materials are among the highest reported. The high adsorption saturation level of these materials, up to 1.9 mmol/g (37% of the adsorbent weight) from gold chloride solutions (potassium tetrachloroaurate) and 2.9 mmol/g (57% of the adsorbent weight) from gold bromide solutions (potassium tetrabromoaurate) at pH = 2, is a noteworthy feature of these materials. This gold loading from [AuC4]- and [AuBr4 ]- solutions corresponds to a relative Au:S molar ratio of 2.5:1 and 3.8:1, respectively. These rates are significantly higher than the usual 1:1 (Au:S) ratio expected for metal ion binding with the material. The additional gold ions loaded have been spontaneously reduced to metallic gold in the mesoporous material. Experimental studies indicated high maximum adsorptions of gold as high as 99.9% recovery. Another promising attribute of these materials is their favourable adsorption kinetics. The MP-HMS reaches equilibrium (saturation) in less than 1 minute of exposure in gold bromide and less than 10 minutes in gold chloride. The MP-HMS materials adsorption is significantly improved by agitation and the adsorption capacity of Au (III) ions increases with the decrease in pH. The recovery of adsorbed gold and the regeneration of spent adsorbent were investigated for MP-HMS adsorbent. The regenerated adsorbent (MP-HMS) maintained its adsorption capacity even after repeated use and all the gold was successfully recovered from the spent adsorbent. For the fist time, a promising adsorbent system has been found that is capable of effectively concentrating gold thiosulphate complexes, whereas conventional carbon-inpulp (CIP) and carbon-in-leach (CIL) systems fail. The gold adsorption shows the high affinity of the mesoporous material to the gold-thiosulphate ([Au (S2O3)2]3- ) ions. A high adsorption saturation level for these materials was found, up to 0.25 mmol (5 mg) Au/g of HMS from gold-thiosulphate solutions. When ammonia was added to the thiosulphate solutions, with or without added copper, the mesoporous material (HMS) achieved the maximum adsorption, 0.24 mmol (47 mg) Au/g of HMS at pH = 7, where as 0.14 mmol (28 mg) Au/g was adsorbed from ammonia-thiosulphate solution at pH > 6. For the fist time, a promising adsorbent system has been found that is capable of effectively concentrating gold thiosulphate complexes, whereas conventional carbon-in-pulp (CIP) and carbon-in-leach (CIL) systems fail. For process design of gold adsorption by HMS particles, certain engineering conditions and practical limitations have to be considered, including particle size of the MP-HMS. Therefore, several experiments have been conducted to enlarge the size of the very fine MP-HMS particles to a size (1--2mm) satisfying the engineering requirements for process design in a real practical and industrial process. The agglomerated mesoporous materials, using sodium metasilicate (Na 2SiO3) binder, adsorbed gold ions in the range of 51%--63% of what the parent HMS powder adsorb. That means the agglomerates can adsorb 19--23% of their own weight (or 190--230 mg Au per one gram of the agglomerated HMS) from [AuCL4]- which is still very satisfactory and acceptable comparing to the current used adsorbents.

Strategy for chemotherapeutic delivery using a nanosized porous metal-organic framework with a central composite design

PubMed Central

Li, Yingpeng; Li, Xiuyan; Guan, Qingxia; Zhang, Chunjing; Xu, Ting; Dong, Yujing; Bai, Xinyu; Zhang, Weiping

2017-01-01

Background Enhancing drug delivery is an ongoing endeavor in pharmaceutics, especially when the efficacy of chemotherapy for cancer is concerned. In this study, we prepared and evaluated nanosized HKUST-1 (nanoHKUST-1), nanosized metal-organic drug delivery framework, loaded with 5-fluorouracil (5-FU) for potential use in cancer treatment. Materials and methods NanoHKUST-1 was prepared by reacting copper (II) acetate [Cu(OAc)2] and benzene-1,3,5-tricarboxylic acid (H3BTC) with benzoic acid (C6H5COOH) at room temperature (23.7°C±2.4°C). A central composite design was used to optimize 5-FU-loaded nanoHKUST-1. Contact time, ethanol concentration, and 5-FU:material ratios were the independent variables, and the entrapment efficiency of 5-FU was the response parameter measured. Powder X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption were used to determine the morphology of nanoHKUST-1. In addition, 5-FU release studies were conducted, and the in vitro cytotoxicity was evaluated. Results Entrapment efficiency and drug loading were 9.96% and 40.22%, respectively, while the small-angle X-ray diffraction patterns confirmed a regular porous structure. The SEM and TEM images of the nanoHKUST-1 confirmed the presence of round particles (diameter: approximately 100 nm) and regular polygon arrays of mesoporous channels of approximately 2–5 nm. The half-maximal lethal concentration (LC50) of the 5-FU-loaded nanoHKUST-1 was approximately 10 µg/mL. Conclusion The results indicated that nanoHKUST-1 is a potential vector worth developing as a cancer chemotherapeutic drug delivery system. PMID:28260892

Improving the controlled release of water-insoluble emodin from amino-functionalized mesoporous silica

NASA Astrophysics Data System (ADS)

Xu, Yunqiang; Wang, Chunfeng; Zhou, Guowei; Wu, Yue; Chen, Jing

2012-06-01

Several types of amino-functionalized mesoporous silica, including F5-SBA-15, F10-SBA-15, and F15-SBA-15 were prepared through co-condensation of tetraethoxysilane (TEOS) and (3-aminopropyl)triethoxysilane (APTES) in varying molar ratios (5 mol%, 10 mol%, and 15 mol%) via a hydrothermal process. The materials obtained were characterized by means of small-angle X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption, Fourier transformed infrared spectra, and X-ray photoelectron spectroscopy. Increasing APTES molar ratios decreased the degree of orderliness of the functionalized mesoporous silica. Pure and amino-functionalized SBA-15 samples were employed as supports for the controlled release of water-insoluble drug emodin. Loading experiments showed that drug loading capacities mainly depended on the surface areas and pore diameters of the carriers. Controlled release profiles of emodin-loaded samples were studied in phosphate buffered saline (PBS, pH 7.4), and results indicated that the emodin release rate could be controlled by surface amino-functionalized carriers. Emodin loaded on functionalized mesoporous supports exhibited a lower release rate than that of loaded on pure SBA-15, emodin loaded on F10-SBA-15 showed the smallest release amount (71.74 wt%) after stirring in PBS for 60 h. Findings suggest that functionalized mesoporous SBA-15 is a promising carrier for achieving prolonged release time periods.

Using the M13 Phage as a Biotemplate to Create Mesoporous Structures Decorated with Gold and Platinum Nanoparticles.

PubMed

Vera-Robles, L Irais; González-Gracida, Jaqueline; Hernández-Gordillo, Armin; Campero, Antonio

2015-08-25

By taking advantage of the physical and chemical properties of the M13 bacteriophage, we have used this virus to synthesize mesoporous silica structures. Major coat protein p8 was chemically modified by attaching thiol groups. As we show, the resulting thiolated phage can be used as a biotemplate able to direct the formation of mesoporous silica materials. Simultaneously, this thiol functionality acts as an anchor for binding metal ions, such as Au(3+) and Pt(4+), forming reactive M13-metal ionic complexes which evolve into metal nanoparticles (NPs) trapped in the mesoporous network. Interestingly, Au(3+) ions are reduced to Au(0) NPs by the protein residues without requiring an external reducing agent. Likewise, silica mesostructures decorated with Au and Pt NPs are prepared in a one-pot synthesis and characterized using different techniques. The obtained results allow us to propose a mechanism of formation. In addition, gold-containing mesoporous structures are tested for the reduction of 4-nitrophenol (4-NP) and methylene blue (MB) in the presence of NaBH4. Although all of the gold-containing catalysts exhibit catalytic activity, those obtained with thiolated phages present a better performance than that obtained with M13 alone. This behavior is ascribed to the position of the Au NPs, which are partially embedded in the wall of the final mesostructures.

Highly active Pd-In/mesoporous alumina catalyst for nitrate reduction.

PubMed

Gao, Zhenwei; Zhang, Yonggang; Li, Deyi; Werth, Charles J; Zhang, Yalei; Zhou, Xuefei

2015-04-09

The catalytic reduction of nitrate is a promising technology for groundwater purification because it transforms nitrate into nitrogen and water. Recent studies have mainly focused on new catalysts with higher activities for the reduction of nitrate. Consequently, metal nanoparticles supported on mesoporous metal oxides have become a major research direction. However, the complex surface chemistry and porous structures of mesoporous metal oxides lead to a non-uniform distribution of metal nanoparticles, thereby resulting in a low catalytic efficiency. In this paper, a method for synthesizing the sustainable nitrate reduction catalyst Pd-In/Al2O3 with a dimensional structure is introduced. The TEM results indicated that Pd and In nanoparticles could efficiently disperse into the mesopores of the alumina. At room temperature in CO2-buffered water and under continuous H2 as the electron donor, the synthesized material (4.9 wt% Pd) was the most active at a Pd-In ratio of 4, with a first-order rate constant (k(obs) = 0.241 L min(-1) g(cata)(-1)) that was 1.3× higher than that of conventional Pd-In/Al2O3 (5 wt% Pd; 0.19 L min(-1) g(cata)(-1)). The Pd-In/mesoporous alumina is a promising catalyst for improving the catalytic reduction of nitrate. Copyright © 2015 Elsevier B.V. All rights reserved.

Chitosan-coated mesoporous microspheres of calcium silicate hydrate: environmentally friendly synthesis and application as a highly efficient adsorbent for heavy metal ions.

PubMed

Zhao, Jing; Zhu, Ying-Jie; Wu, Jin; Zheng, Jian-Qiang; Zhao, Xin-Yu; Lu, Bing-Qiang; Chen, Feng

2014-03-15

Chitosan-coated calcium silicate hydrate (CSH/chitosan) mesoporous microspheres formed by self-assembly of nanosheets have been synthesized in aqueous solution under ambient conditions without using any toxic surfactant or organic solvent. The method reported herein has advantages of simplicity, low cost and being environmentally friendly. The BET specific surface area of CSH/chitosan mesoporous microspheres is measured to be as high as ~356 m(2) g(-1), which is considerably high among calcium silicate materials. The as-prepared CSH/chitosan mesoporous microspheres are promising adsorbent and exhibit a quick and highly efficient adsorption behavior toward heavy metal ions of Ni(2+), Zn(2+), Cr(3+), Pb(2+) Cu(2+) and Cd(2+) in aqueous solution. The adsorption kinetics can be well fitted by the pseudo second-order model. The maximum adsorption amounts of Ni(2+), Zn(2+), Pb(2+), Cu(2+) and Cd(2+) on CSH/chitosan mesoporous microspheres are extremely high, which are 406.6, 400, 796, 425 and 578 mg/g, respectively. The CSH/chitosan adsorbent exhibits the highest affinity for Pb(2+) ions among five heavy metal ions. The adsorption capacities of the CSH/chitosan adsorbent toward heavy metal ions are relatively high compared with those reported in the literature. Copyright © 2013 Elsevier Inc. All rights reserved.

Composite material for optical oxygen sensor

NASA Astrophysics Data System (ADS)

Antropov, A. P.; Ragutkin, A. V.; Melnikov, P. V.; Luchnikov, P. A.; Zaitsev, N. K.

2018-01-01

A new composite material for use in optical molecular oxygen sensors is proposed. The absence of pores on the surface of the material avoids microbiological fouling and concomitant deterioration of the characteristics with time, and the presence of the mesoporous phase results in a linear calibration and acceptable response times, even for layers that are significant in thickness.

Mesoporous carbon-coated LiFePO4 nanocrystals co-modified with graphene and Mg2+ doping as superior cathode materials for lithium ion batteries.

PubMed

Wang, Bo; Xu, Binghui; Liu, Tiefeng; Liu, Peng; Guo, Chenfeng; Wang, Shuo; Wang, Qiuming; Xiong, Zhigang; Wang, Dianlong; Zhao, X S

2014-01-21

In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg(2+) doping (G/LFMP) were synthesized by a modified rheological phase method to improve the speed of lithium storage as well as cycling stability. The mesoporous structure of LiFePO4 nanocrystals was designed and realized by introducing the bead milling technique, which assisted in forming sucrose-pyrolytic carbon nanoparticles as the template for generating mesopores. For comparison purposes, samples modified only with graphene (G/LFP) or Mg(2+) doping (LFMP) as well as pure LiFePO4 (LFP) were also prepared and investigated. Microscopic observation and nitrogen sorption analysis have revealed the mesoporous morphologies of the as-prepared composites. X-ray diffraction (XRD) and Rietveld refinement data demonstrated that the Mg-doped LiFePO4 is a single olivine-type phase and well crystallized with shortened Fe-O and P-O bonds and a lengthened Li-O bond, resulting in an enhanced Li(+) diffusion velocity. Electrochemical properties have also been investigated after assembling coin cells with the as-prepared composites as the cathode active materials. Remarkably, the G/LFMP composite has exhibited the best electrochemical properties, including fast lithium storage performance and excellent cycle stability. That is because the modification of graphene provided active sites for nuclei, restricted the in situ crystallite growth, increased the electronic conductivity and reduced the interface reaction current density, while, Mg(2+) doping improved the intrinsically electronic and ionic transfer properties of LFP crystals. Moreover, in the G/LFMP composite, the graphene component plays the role of "cushion" as it could quickly realize capacity response, buffering the impact to LFMP under the conditions of high-rate charging or discharging, which results in a pre-eminent rate capability and cycling stability.

Synthesis of Nitrogen-Doped Mesoporous Carbon for the Catalytic Oxidation of Ethylbenzene

NASA Astrophysics Data System (ADS)

Wang, Ruicong; Yu, Yifeng; Zhang, Yue; Lv, Haijun; Chen, Aibing

2017-06-01

Nitrogen-doped ordered mesoporous carbon (NOMC) was fabricated via a simple hard-template method by functionalized ionic liquids as carbon and nitrogen source, SBA-15 as a hard-template. The obtained NOMC materials have a high nitrogen content of 5.55 %, a high surface area of 446.2 m2 g-1, and an excellent performance in catalysing oxidation of ethylbenzene. The conversion rate of ethylbenzene can be up to 84.5% and the yield of acetophenone can be up to 69.9%, the results indicated that the NOMC materials have a faster catalytic rate and a higher production of acetophenone than catalyst-free and CMK-3, due to their uniform pore size, high surface area and rich active sites in the carbon pore walls.

Mesoporous orthorhombic Nb2O5 nanofibers as pseudocapacitive electrodes with ultra-stable Li storage characteristics

NASA Astrophysics Data System (ADS)

Cheong, Jun Young; Jung, Ji-Won; Youn, Doo-Young; Kim, Chanhoon; Yu, Sunmoon; Cho, Su-Ho; Yoon, Ki Ro; Kim, Il-Doo

2017-08-01

Ultra-stable pseudocapacitive electrodes for lithium-ion batteries (LIBs) are increasing in demand as highly sustainable energy storage system with excellent charge transport is important. The establishment of facile, controllable, and scalable synthesis of pseudocapacitive electrode materials is an attractive solution to realize such objectives. Here, we have successfully fabricated mesoporous orthorhombic Nb2O5 nanofibers (m-T-Nb2O5 NFs) by simple single-spinneret electrospinning followed by calcination at 600 °C. As-formed m-T-Nb2O5 NFs exhibit high surface area (23.7 m2 g-1) and a number of mesopores in the vacant sites where organic polymer was once decomposed. Such rationally designed m-T-Nb2O5-NFs allow facile Li ion and electron transport, with pseudocapacitive behavior. Arising from the high surface area coupled with mesopores in-between the Nb2O5 nanograins, it exhibits ultra-long cycle retention (a capacity of ∼160 mAh g-1 at 500 mA g-1 after 2000 cycles and ∼88 mAh g-1 at 3000 mA g-1 after 5000 cycles) and higher rate capability (∼70 mAh g-1 at 5000 mA g-1). Such cycle retention characteristics of m-T-Nb2O5-NFs are at least 100-fold slower capacity decay compared with previously reported one-dimensional (1D) Nb2O5 nanostructures and even superior or comparable to recently reported Nb2O5-graphene composite materials.

Ti2Nb10O29-x mesoporous microspheres as promising anode materials for high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Deng, Shengjue; Luo, Zhibin; Liu, Yating; Lou, Xiaoming; Lin, Chunfu; Yang, Chao; Zhao, Hua; Zheng, Peng; Sun, Zhongliang; Li, Jianbao; Wang, Ning; Wu, Hui

2017-09-01

Ti2Nb10O29 has recently been reported as a promising anode material for lithium-ion batteries. However, its poor electronic conductivity and insufficient Li+-ion diffusion coefficient significantly limit its rate capability. To tackle this issue, a strategy combining nanosizing and crystal-structure modification is employed. Ti2Nb10O29-x mesoporous microspheres with a sphere-size range of 0.5-4 μm are prepared by a one-step solvothermal method followed by thermal treatment in N2. These Ti2Nb10O29-x mesoporous microspheres exhibit primary nanoparticles, a large specific surface area (22.9 m2 g-1) and suitable pore sizes, leading to easy electron/Li+-ion transport and good interfacial reactivity. Ti2Nb10O29-x shows a defective shear ReO3 crystal structure with O2- vacancies and an increased unit cell volume, resulting in its increased Li+-ion diffusion coefficient. Besides Ti4+ and Nb5+ ions, Ti2Nb10O29-x comprises Nb4+ ions with unpaired 4d electrons, which significantly increase its electronic conductivity. As a result of these improvements, the Ti2Nb10O29-x mesoporous microspheres reveal superior electrochemical performances in term of large reversible specific capacity (309 mAh g-1 at 0.1 C), outstanding rate capability (235 mAh g-1 at 40 C) and durable cyclic stability (capacity retention of 92.1% over 100 cycles at 10 C).

Active Iron Sites of Disordered Mesoporous Silica Catalyst FeKIL-2 in the Oxidation of Volatile Organic Compounds (VOC)

PubMed Central

Rangus, Mojca; Mazaj, Matjaž; Dražić, Goran; Popova, Margarita; Tušar, Nataša Novak

2014-01-01

Iron-functionalized disordered mesoporous silica (FeKIL-2) is a promising, environmentally friendly, cost-effective and highly efficient catalyst for the elimination of volatile organic compounds (VOCs) from polluted air via catalytic oxidation. In this study, we investigated the type of catalytically active iron sites for different iron concentrations in FeKIL-2 catalysts using advanced characterization of the local environment of iron atoms by a combination of X-ray Absorption Spectroscopy Techniques (XANES, EXAFS) and Atomic-Resolution Scanning Transmission Electron Microscopy (AR STEM). We found that the molar ratio Fe/Si ≤ 0.01 leads to the formation of stable, mostly isolated Fe3+ sites in the silica matrix, while higher iron content Fe/Si > 0.01 leads to the formation of oligonuclear iron clusters. STEM imaging and EELS techniques confirmed the existence of these clusters. Their size ranges from one to a few nanometers, and they are unevenly distributed throughout the material. The size of the clusters was also found to be similar, regardless of the nominal concentration of iron (Fe/Si = 0.02 and Fe/Si = 0.05). From the results obtained from sample characterization and model catalytic tests, we established that the enhanced activity of FeKIL-2 with the optimal Fe/Si = 0.01 ratio can be attributed to: (1) the optimal concentration of stable isolated Fe3+ in the silica support; and (2) accelerated diffusion of the reactants in disordered mesoporous silica (FeKIL-2) when compared to ordered mesoporous silica materials (FeSBA-15, FeMCM-41). PMID:28788674

Enhanced photo-catalytic activity of ordered mesoporous indium oxide nanocrystals in the conversion of CO2 into methanol.

PubMed

Gondal, M A; Dastageer, M A; Oloore, L E; Baig, U; Rashid, S G

2017-07-03

Ordered mesoporous indium oxide nanocrystal (m-In 2 O 3 ) was synthesized by nanocasting technique, in which highly ordered mesoporous silca (SBA-15) was used as structural matrix. X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halanda (BJH) studies were carried out on m-In 2 O 3 and the results revealed that this material has a highly ordered mesoporous surface with reduced grain size, increased surface area and surface volume compared to the non porous indium oxide. The diffuse reluctance spectrum exhibited substantially improved light absorption efficiency in m-In 2 O 3 compared to normal indium oxide, however, no considerable change in the band gap energies of these materials was observed. When m-In 2 O 3 was used as a photo-catalyst in the photo-catalytic process of converting carbon dioxide (CO 2 ) into methanol under the pulsed laser radiation of 266-nm wavelengths, an enhanced photo-catalytic activity with the quantum efficiency of 4.5% and conversion efficiency of 46.3% were observed. It was found that the methanol production yield in this chemical process is as high as 485 µlg -1 h -1 after 150 min of irradiation, which is substantially higher than the yields reported in the literature. It is quite clear from the results that the introduction of mesoporosity in indium oxide, and the consequent enhancement of positive attributes required for a photo-catalyst, transformed photo-catalytically weak indium oxide into an effective photo-catalyst for the conversion of CO 2 into methanol.

Comparative study of the methane and methanol mass transfer in the mesoporous H-ZSM-5/alumina extruded pellet

NASA Astrophysics Data System (ADS)

Zhokh, Alexey A.; Strizhak, Peter E.

2018-07-01

H-ZSM-5/alumina catalyst pellet was prepared using extrusion method. The as-prepared mesoporous material was characterized using nitrogen adsorption, IR, XRD, and TEM methods. Transport of methane and methanol in the obtained H-ZSM-5/alumina extruded grain was studied. We demonstrate that the methanol transport may be described by the time-fractional diffusion equation in a fairly good manner. The measured value of the fractional order of the time-fractional derivative reveals the fast super-diffusive regime of the methanol transport in the mesoporous solid. Contrary, the methane transport has been found to follow a standard diffusion and described by the second Fick's law. These findings show that mass transfer kinetics is characterized by the order of the temporal derivative. The latter is a unique property of the individual porous media and the diffusing agent.

Comparative study of the methane and methanol mass transfer in the mesoporous H-ZSM-5/alumina extruded pellet

NASA Astrophysics Data System (ADS)

Zhokh, Alexey A.; Strizhak, Peter E.

2018-01-01

H-ZSM-5/alumina catalyst pellet was prepared using extrusion method. The as-prepared mesoporous material was characterized using nitrogen adsorption, IR, XRD, and TEM methods. Transport of methane and methanol in the obtained H-ZSM-5/alumina extruded grain was studied. We demonstrate that the methanol transport may be described by the time-fractional diffusion equation in a fairly good manner. The measured value of the fractional order of the time-fractional derivative reveals the fast super-diffusive regime of the methanol transport in the mesoporous solid. Contrary, the methane transport has been found to follow a standard diffusion and described by the second Fick's law. These findings show that mass transfer kinetics is characterized by the order of the temporal derivative. The latter is a unique property of the individual porous media and the diffusing agent.

Synthesis of a large-sized mesoporous phosphosilicate thin film through evaporation-induced polymeric micelle assembly.

PubMed

Li, Yunqi; Bastakoti, Bishnu Prasad; Imura, Masataka; Suzuki, Norihiro; Jiang, Xiangfen; Ohki, Shinobu; Deguchi, Kenzo; Suzuki, Madoka; Arai, Satoshi; Yamauchi, Yusuke

2015-01-01

A triblock copolymer, poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-b-P2VP-b-PEO) was used as a soft template to synthesize large-sized mesoporous phosphosilicate thin films. The kinetically frozen PS core stabilizes the micelles. The strong interaction of the inorganic precursors with the P2VP shell enables the fabrication of highly robust walls of phosphosilicate and the PEO helps orderly packing of the micelles during solvent evaporation. The molar ratio of phosphoric acid and tetraethyl orthosilicate is crucial to achieve the final mesostructure. The insertion of phosphorus species into the siloxane network is studied by (29) Si and (31) P MAS NMR spectra. The mesoporous phosphosilicate films exhibit steady cell adhesion properties and show great promise as excellent materials in bone-growth engineering applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In-situ space-confined catalysis for fabricating 3D mesoporous graphene and their capacitive properties

NASA Astrophysics Data System (ADS)

Qin, Jian; Zhu, Shan; Feng, Chao; Zhao, Naiqin; Shi, Chunsheng; Liu, En-Zuo; He, Fang; Ma, Liying; Li, Jiajun; He, Chunnian

2018-03-01

A one-step strategy for preparing 3D mesoporous graphene networks (3DMGNs) based on the concepts of space-confined effect, catalytic effect and chemical activation is reported in this work. The soluble salts act as the in-situ templates to confine the thickness of 3D graphene layers. Meanwhile, the Fe-catalysts greatly improve the graphitization of the graphene matrix, which are easy to be removed by acid treatment. In addition, the KOH activation introduces abundant mesopores into the graphene networks, which facilities the electrolyte permeation. Thus, when using as electrode materials for supercapacitor, the as-obtained 3DMGNs with high electron conductivity, large surface area and hierarchical porous structure exhibit excellent capacitive properties, including high specific capacitance (215 F g-1 at 0.5 A g-1) and superior rate performance (168 F g-1 at 50 A g-1).

Synthesis and characterization of thermally stable zirconia based mesoporous nanosilica with metalloporphyrin encapsulation

NASA Astrophysics Data System (ADS)

Nadeem, Saad; Iqbal, Farukh; Mutalib, Mohamed Ibrahim Abdul; Abdullah, Bawadi; Shaharun, Maizatul Shima

2017-10-01

Metal composite materials-48 (MCM-48) with silica zirconia mesoporous matrix (having a Zr/Si ratio of 0.02) has been developed successfully using autogenous conditions and Copper tetra phenyl porphyrin (CuTPP) inclusion via flexible ligand approach. Thermo gravimetric analysis (TGA) was used to study the thermal stability which gives the stability up to 700°C, Fourier transform infrared spectroscopy (FTIR) for the functional group attachment also confirmed the MCM-48 structure and the Zirconia addition and X-Ray photon spectroscopy (XPS) for the binding energies and bonding also revealed the surface Zr4+ states. DRS-UV-Vis study for the photophysical behaviour, visible light activation and band gap reduction which reduced from 5.6 to 2.8 eV. All the characterizations have confirmed that nanoscale mesoporous silica with successful inclusion of zirconia in the matrix and the encapsulation of CuTPP was confirmed via diffuse reflectance (DR Uv-Vis) spectroscopy.

High-performance mesoporous LiFePO₄ from Baker's yeast.

PubMed

Zhang, Xudong; Zhang, Xueguang; He, Wen; Sun, Caiyun; Ma, Jingyun; Yuan, Junling; Du, Xiaoyong

2013-03-01

Based on the biomineralization assembly concept, a simple and inexpensive biomimetic sol-gel method is found to synthesize high-performance mesoporous LiFePO(4) (HPM-LFP). The key step of this approach is to apply Baker's yeast cells as both a structural template and a biocarbon source. The formation mechanism of ordered hierarchical mesoporous network structure is revealed by characterizing its morphology and microstructure. The HPM-LFP exhibits outstanding electrochemical performances. The HPM-LFP has a high discharge capacity (about 153 mAh g(-1) at a 0.1 C rate), only 2% capacity loss from the initial value after 100 cycles at a current density of 0.1 C. This simple and potentially universal design strategy is currently being pursued in the synthesis of an ideal cathode-active material for high power applications. Copyright © 2012 Elsevier B.V. All rights reserved.

Fabrication of diverse pH-sensitive functional mesoporous silica for selective removal or depletion of highly abundant proteins from biological samples.

PubMed

Wang, Jiaojiao; Lan, Jingfeng; Li, Huihui; Liu, Xiaoyan; Zhang, Haixia

2017-01-01

In proteomic studies, poor detection of low abundant proteins is a major problem due to the presence of highly abundant proteins. Therefore, the specific removal or depletion of highly abundant proteins prior to analysis is necessary. In response to this problem, a series of pH-sensitive functional mesoporous silica materials composed of 2-(diethylamino)ethyl methacrylate and methacrylic acid units were designed and synthesized via atom transfer radical polymerization. These functional mesoporous silica materials were characterized and their ability for adsorption and separation of proteins was evaluated. Possessing a pH-sensitive feature, the synthesized functional materials showed selective adsorption of some proteins in aqueous or buffer solutions at certain pH values. The specific removal of a particular protein from a mixed protein solution was subsequently studied. The analytical results confirmed that all the target proteins (bovine serum albumin, ovalbumin, and lysozyme) can be removed by the proposed materials from a five-protein mixture in a single operation. Finally, the practical application of this approach was also evaluated by the selective removal of certain proteins from real biological samples. The results revealed that the maximum removal efficiencies of ovalbumin and lysozyme from egg white sample were obtained as 99% and 92%, respectively, while the maximum removal efficiency of human serum albumin from human serum sample was about 80% by the proposed method. It suggested that this treatment process reduced the complexity of real biological samples and facilitated the identification of hidden proteins in chromatograms. Copyright © 2016 Elsevier B.V. All rights reserved.

Mesoporous block-copolymer nanospheres prepared by selective swelling.

PubMed

Mei, Shilin; Jin, Zhaoxia

2013-01-28

Block-copolymer (BCP) nanospheres with hierarchical inner structure are of great interest and importance due to their possible applications in nanotechnology and biomedical engineering. Mesoporous BCP nanospheres with multilayered inner channels are considered as potential drug-delivery systems and templates for multifunctional nanomaterials. Selective swelling is a facile pore-making strategy for BCP materials. Herein, the selective swelling-induced reconstruction of BCP nanospheres is reported. Two poly(styrene-block-2-vinylpyridine) (PS-b-P2VP) samples with different compositions (PS(23600)-b-P2VP(10400) and PS(27700)-b-P2VP(4300)) are used as model systems. The swelling reconstruction of PS-b-P2VP in ethanol, 1-pyrenebutyric acid (PBA)/ethanol, or HCl/ethanol (pH = 2.61) is characterized by scanning electron microscopy and transmission electron microscopy. It is observed that the length of the swellable block in BCP is a critical factor in determining the behavior and nanostructures of mesoporous BCP nanospheres in selective swelling. Moreover, it is demonstrated that the addition of PBA modifies the swelling structure of PS(23600)-b-P2VP(10400) through the interaction between PBA and P2VP blocks, which results in BCP nanospheres with patterned pores of controllable size. The patterned pores can be reversibly closed by annealing the mesoporous BCP nanospheres in different selective solvents. The controllable and reversible open/closed reconstruction of BCP nanospheres can be used to enclose functional nanoparticles or drugs inside the nanospheres. These mesoporous BCP nanospheres are further decorated with gold nanoparticles by UV photoreduction. The enlarged decoration area in mesoporous BCP nanospheres will enhance their activity and sensitivity as a catalyst and electrochemical sensor. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High drug load, stable, manufacturable and bioavailable fenofibrate formulations in mesoporous silica: a comparison of spray drying versus solvent impregnation methods.

PubMed

Hong, Shiqi; Shen, Shoucang; Tan, David Cheng Thiam; Ng, Wai Kiong; Liu, Xueming; Chia, Leonard S O; Irwan, Anastasia W; Tan, Reginald; Nowak, Steven A; Marsh, Kennan; Gokhale, Rajeev

2016-01-01

Encapsulation of drugs in mesoporous silica using co-spray drying process has been recently explored as potential industrial method. However, the impact of spray drying on manufacturability, physiochemical stability and bioavailability in relation to conventional drug load processes are yet to be fully investigated. Using a 2(3) factorial design, this study aims to investigate the effect of drug-loading process (co-spray drying and solvent impregnation), mesoporous silica pore size (SBA-15, 6.5 nm and MCM-41, 2.5 nm) and percentage drug load (30% w/w and 50% w/w) on material properties, crystallinity, physicochemical stability, release profiles and bioavailability of fenofibrate (FEN) loaded into mesoporous silica. From the scanning electronic microscopy (SEM) images, powder X-ray diffraction and Differential scanning calorimetry measurements, it is indicated that the co-spray drying process was able to load up to 50% (w/w) FEN in amorphous form onto the mesoporous silica as compared to the 30% (w/w) for solvent impregnation. The in vitro dissolution rate of the co-spray dried formulations was also significantly (p = 0.044) better than solvent impregnated formulations at the same drug loading. Six-month accelerated stability test at 40 °C/75 RH in open dish indicated excellent physical and chemical stability of formulations prepared by both methods. The amorphous state of FEN and the enhanced dissolution profiles were well preserved, and very low levels of degradation were detected after storage. The dog data for the three selected co-spray-dried formulations revealed multiple fold increment in FEN bioavailability compared to the reference crystalline FEN. These results validate the viability of co-spray-dried mesoporous silica formulations with high amorphous drug load as potential drug delivery systems for poorly water soluble drugs.

General and simple approach for control cage and cylindrical mesopores, and thermal/hydrothermal stable frameworks.

PubMed

El-Safty, Sherif A; Mizukami, Fujio; Hanaoka, Takaaki

2005-05-19

Highly ordered cage and cylindrical mesoporeous silica monoliths (HOM) with 2- and 3-dimensional (2D and 3D, respectively) structures, mesopore/micropore volumes, and thick-walled frameworks were successfully fabricated by instant direct templating of lyotropic phases of copolymer (EO(m)-PO(n)-EO(m)) surfactants. Large cage-like pores with uniform constriction sizes up to 10 nm and open cylindrical channel-like mesopores can be easily achieved by this simple and efficient synthesis design. Our results show that the cage-like pores could be fabricated at relatively lower copolymer concentrations used in the lyotropic phase domains at copolymer/TMOS ratios of 35 wt %. These ordered cage pore architectures underwent transition to open-cylindrical pores by increasing the copolymer concentration. High EO/PO block copolymers, in general, were crucially affected on the increase of the interior cavity sizes and on the stability of the cage mesopore characters. However, for F108 (EO(141)PO(44)EO(141)) systems, the fabrication of ordered and stable cage pore monoliths was achieved with significantly higher copolymer concentrations up to 90 wt %. Interestingly, the effective copolymer molecular nature was also observed in the ability to design various ordered mesophase geometries in large domain sizes. Our findings here show evidence that the synthetic strategy provides realistic control over a wide range of mesostructured phase geometries and their extended long-range ordering in the final replicas of the silica monolith frameworks. In addition, the HOM silica monoliths exhibited considerable structural stability against higher thermal temperature (up to 1000 degrees C) and longer hydrothermal treatment times under boiling water and steam. The remarkable structural findings of 3D frameworks, transparent monoliths, and micropores combined with large cage- and cylindrical-like mesopores are expected to find promising uses in materials chemistry.

High rate sodium ion battery anodes from block copolymer templated mesoporous nickel–cobalt carbonates and oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhaway, Sarang M.; Tangvijitsakul, Pattarasai; Lee, Jeongwoo

2015-09-16

Micelle-templated ordered mesoporous nickel–cobalt carbonates and oxides are fabricated using a metal nitrate–citric acid strategy, which avoids the hydrolysis and aging requirements associated with sol–gel chemistry. A series of mesoporous Ni xCo (3-x)(CO 3) y and Ni xCo (3-x)O 4 films with varying Ni–Co compositions and 14 ± 4 nm mesopores are fabricated with the same block copolymer template. AFM and GISAXS analysis indicates that the mesostructure is maintained through the formation of the carbonate and oxide, while GIXD profiles confirm formation of pure spinel phases of semi-crystalline Ni xCo (3-x)O 4. The micelle templated mesopores are interconnected and providemore » transport paths for the electrolyte to minimize the solid-state diffusion requirements associated with battery electrodes. These materials exhibit good performance as sodium ion battery anodes even at high current densities of 4 A g -1. Amongst the mixed-metal oxides, Ni 2CoO 4 exhibits the highest specific capacity of 239 mA h g -1 after galvanostatic cycling at a current density of 1 A g -1 for 10 cycles. We attribute the superior performance of Ni 2CoO 4 at high rates to the high surface area and short ion-diffusion paths of the nanoporous anode architecture, while the higher nickel content in the mixed metal oxide provides enhanced stability during oxide formation along with enhanced electronic conductivity, leading to improved cycling stability of the anode. This micelle template metal nitrate–citric acid method enables new possibilities for fabricating variety of ordered mesoporous mixed-metal carbonates and oxides that could be used in a wide range of applications.« less

A Magnetic-Field Guided Interface Coassembly Approach to Magnetic Mesoporous Silica Nanochains for Osteoclast-Targeted Inhibition and Heterogeneous Nanocatalysis.

PubMed

Wan, Li; Song, Hongyuan; Chen, Xiao; Zhang, Yu; Yue, Qin; Pan, Panpan; Su, Jiacan; Elzatahry, Ahmed A; Deng, Yonghui

2018-06-01

1D core-shell magnetic materials with mesopores in shell are highly desired for biocatalysis, magnetic bioseparation, and bioenrichment and biosensing because of their unique microstructure and morphology. In this study, 1D magnetic mesoporous silica nanochains (Fe 3 O 4 @nSiO 2 @mSiO 2 nanochain, Magn-MSNCs named as FDUcs-17C) are facilely synthesized via a novel magnetic-field-guided interface coassembly approach in two steps. Fe 3 O 4 particles are coated with nonporous silica in a magnetic field to form 1D Fe 3 O 4 @nSiO 2 nanochains. A further interface coassembly of cetyltrimethylammonium bromide and silica source in water/n-hexane biliquid system leads to 1D Magn-MSNCs with core-shell-shell structure, uniform diameter (≈310 nm), large and perpendicular mesopores (7.3 nm), high surface area (317 m 2 g -1 ), and high magnetization (34.9 emu g -1 ). Under a rotating magnetic field, the nanochains with loaded zoledronate (a medication for treating bone diseases) in the mesopores, show an interesting suppression effect of osteoclasts differentiation, due to their 1D nanostructure that provides a shearing force in dynamic magnetic field to induce sufficient and effective reactions in cells. Moreover, by loading Au nanoparticles in the mesopores, the 1D Fe 3 O 4 @nSiO 2 @mSiO 2 -Au nanochains can service as a catalytically active magnetic nanostirrer for hydrogenation of 4-nitrophenol with high catalytic performance and good magnetic recyclability. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of Mesoporous Co2+-Doped TiO2 Nanodisks Derived from Metal Organic Frameworks with Improved Sodium Storage Performance.

PubMed

Hong, Zhensheng; Kang, Meiling; Chen, Xiaohui; Zhou, Kaiqiang; Huang, Zhigao; Wei, Mingdeng

2017-09-20

TiO 2 is a most promising anode candidate for rechargeable Na-ion batteries (NIBs) because of its appropriate working voltage, low cost, and superior structural stability during chage/discharge process. Nevertheless, it suffers from intrinsically low electrical conductivity. Herein, we report an in situ synthesis of Co 2+ -doped TiO 2 through the thermal treatment of metal organic frameworks precursors of MIL-125(Ti)-Co as a superior anode material for NIBs. The Co 2+ -doped TiO 2 possesses uniform nanodisk morphology, a large surface area and mesoporous structure with narrow pore distribution. The reversible capacity, Coulombic efficiency (CE) and rate capability can be improved by Co 2+ doping in mesoporous TiO 2 anode. Co 2+ -doped mesoporous TiO 2 nanodisks exhibited a high reversible capacity of 232 mAhg -1 at 0.1 Ag 1- , good rate capability and cycling stability with a stable capacity of about 140 mAhg -1 at 0.5 Ag 1- after 500 cycles. The enhanced Na-ion storage performance could be due to the increased electrical conductivity revealed by Kelvin probe force microscopy measurements.

Gas-generated thermal oxidation of a coordination cluster for an anion-doped mesoporous metal oxide.

PubMed

Hirai, Kenji; Isobe, Shigehito; Sada, Kazuki

2015-12-18

Central in material design of metal oxides is the increase of surface area and control of intrinsic electronic and optical properties, because of potential applications for energy storage, photocatalysis and photovoltaics. Here, we disclose a facile method, inspired by geochemical process, which gives rise to mesoporous anion-doped metal oxides. As a model system, we demonstrate that simple calcination of a multinuclear coordination cluster results in synchronic chemical reactions: thermal oxidation of Ti8O10(4-aminobenzoate)12 and generation of gases including amino-group fragments. The gas generation during the thermal oxidation of Ti8O10(4-aminobenzoate)12 creates mesoporosity in TiO2. Concurrently, nitrogen atoms contained in the gases are doped into TiO2, thus leading to the formation of mesoporous N-doped TiO2. The mesoporous N-doped TiO2 can be easily synthesized by calcination of the multinuclear coordination cluster, but shows better photocatalytic activity than the one prepared by a conventional sol-gel method. Owing to an intrinsic designability of coordination compounds, this facile synthetic will be applicable to a wide range of metal oxides and anion dopants.

Facile and Low-cost Synthesis of Mesoporous Ti-Mo Bi-metal Oxide Catalysts for Biodiesel Production from Esterification of Free Fatty Acids in Jatropha curcas Crude Oil.

PubMed

Zhang, Qiuyun; Li, Hu; Yang, Song

2018-05-01

Mesoporous Ti-Mo bi-metal oxides with various titanium-molybdenum ratios were successfully fabricated via a facile approach by using stearic acid as a low-cost template agent. thermal gravity (TG) /differential scanning calorimetry (DSC) analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, nitrogen adsorption-desorption isotherm, NH 3 temperature-programmed desorption (NH 3 -TPD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements indicated these materials possessing mesoporous structure, sufficient pore size and high acid intensity. The catalytic performance of prepared catalysts was evaluated by esterification of free fatty acids in Jatropha curcas crude oil (JCCO) with methanol. The effects of various parameters on FFA conversion were investigated. The esterification conversion of 87.8% was achieved under the condition of 180°C, 2 h, methanol to JCCO molar ratio of 20:1 and 3.0 wt.% catalyst (relative to the weight of JCCO). The mesoporous catalysts were found to exhibit high activities toward the simultaneous esterification and transesterification of JCCO. Furthermore, the catalyst could be recovered with a good reusability.

One-pot pseudomorphic crystallization of mesoporous porous silica to hierarchical porous zeolites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xing, Jun-Ling; Jiang, Shu-Hua; Pang, Jun-Ling

2015-09-15

Hierarchically porous silica with mesopore and zeolitic micropore was synthesized via pseudomorphic crystallization under high-temperature hydrothermal treatment in the presence of cetyltrimethylammonium tosylate and tetrapropylammonium ions. A combined characterization using small-angle X-ray diffraction (XRD), nitrogen adsorption, high-resolution transmission electron microscopy (TEM), thermogravimetric analysis (TG), and elemental analysis showed that dual templates, CTA{sup +} and TPA{sup +} molecules, can work in a cooperative manner to synthesize mesoporous zeolite in a one-pot system by precisely tuning the reaction conditions, such as reaction time and temperature, and type and amount of heterometal atoms. It is found that the presence of Ti precursor ismore » critical to the successful synthesis of such nanostructure. It not only retards the nucleation and growth of crystalline MFI domains, but also acts as nano-binder or nano-glue to favor the assembly of zeolite nanoblocks. - Graphical abstract: Display Omitted - Highlights: • A facile method to synthesize mesoporous zeolites with hierarchical porosity was presented. • It gives a new insight into keeping the balance between mesoscopic and molecular ordering in hierarchical porous materials. • A new understanding on the solid–solid transformation mechanism for the synthesis of titanosilicate zeolites was proposed.« less

High performance sulfur, nitrogen and carbon doped mesoporous anatase-brookite TiO₂ photocatalyst for the removal of microcystin-LR under visible light irradiation.

PubMed

El-Sheikh, Said M; Zhang, Geshan; El-Hosainy, Hamza M; Ismail, Adel A; O'Shea, Kevin E; Falaras, Polycarpos; Kontos, Athanassios G; Dionysiou, Dionysios D

2014-09-15

Carbon, nitrogen and sulfur (C, N and S) doped mesoporous anatase-brookite nano-heterojunction titania photocatalysts have been synthesized through a simple sol-gel method in the presence of triblock copolymer Pluronic P123. XRD and Raman spectra revealed the formation of anatase and brookite mixed phases. XPS spectra indicated the presence of C, N and S dopants. The TEM images demonstrated the formation of almost monodisperse titania nanoparticles with particle sizes of approximately 10nm. N2 isotherm measurements confirmed that both doped and undoped titania anatase-brookite materials have mesoporous structure. The photocatalytic degradation of the cyanotoxin microcystin-LR (MC-LR) has been investigated using these novel nanomaterials under visible light illumination. The photocatalytic efficiency of the mesoporous titania anatase-brookite photocatalyst dramatically increased with the addition of the C, N and S non-metal, achieving complete degradation (∼ 100 %) of MC-LR. The results demonstrate the advantages of the synthetic approach and the great potential of the visible light activated C, N, and S doped titania photocatalysts for the treatment of organic micropollutants in contaminated waters under visible light. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis of mesoporous TiO(2-x)N(x) spheres by template free homogeneous co-precipitation method and their photo-catalytic activity under visible light illumination.

PubMed

Parida, K M; Naik, Brundabana

2009-05-01

The article presents preparation, characterization and catalytic activity evaluation of an efficient nitrogen doped mesoporous titania sphere photo-catalyst for degradation of methylene blue (MB) and methyl orange (MO) under visible light illumination. Nitrogen doped titania was prepared by soft chemical route i.e. template free, slow and controlled homogeneous co-precipitation from titanium oxysulfate sulfuric acid complex hydrate, urea, ethanol and water. The molar composition of TiOSO(4) to urea was varied to prepare different atomic % nitrogen doped titania. Mesoporous anatase TiO(2-x)N(x) spheres with average crystallite size of 10 nm and formation of titanium oxynitride center were confirmed from HRTEM, XRD and XPS study. UV-vis DRS showed a strong absorption in the range of 400-500 nm which supports its use in visible spectrum of light. Nitrogen adsorption-desorption study supports the porous nature of the doped material. All the TiO(2-x)N(x) samples showed higher photo-catalytic activity than Degussa P(25) and undoped mesoporous titania. Sample containing around one atomic % nitrogen showed highest activity among the TiO(2-x)N(x) samples.

3-D periodic mesoporous nickel oxide for nonenzymatic uric acid sensors with improved sensitivity

NASA Astrophysics Data System (ADS)

Huang, Wei; Cao, Yang; Chen, Yong; Zhou, Yang; Huang, Qingyou

2015-12-01

3-D periodic mesoporous nickel oxide (NiO) particles with crystalline walls have been synthesized through the microwave-assisted hard template route toward the KIT-6 silica. It was investigated as a nonenzymatic amperometric sensor for the detection of uric acid. 3-D periodic nickel oxide matrix has been obtained by the hard template route from the KIT-6 silica template. The crystalline nickel oxide belonged to the Ia3d space group, and its structure was characterized by X-ray diffraction (XRD), N2 adsorption-desorption, and transmission electron microscopy (TEM). The analysis results showed that the microwave-assisted mesoporous NiO materials were more appropriate to be electrochemical sensors than the traditional mesoporous NiO. Cyclic voltammetry (CV) revealed that 3-D periodic NiO exhibited a direct electrocatalytic activity for the oxidation of uric acid in sodium hydroxide solution. The enzyme-less amperometric sensor used in the detection of uric acid with detection limit of 0.005 μM (S/N = 3) over wide linear detection ranges up to 0.374 mM and with a high sensitivity of 756.26 μA mM-1 cm-2, and a possible mechanism was also given in the paper.

Mesoporous Co3O4 nanostructured material synthesized by one-step soft-templating: A magnetic study

NASA Astrophysics Data System (ADS)

Poyraz, Altug S.; Hines, William A.; Kuo, Chung-Hao; Li, Nan; Perry, David M.; Suib, Steven L.

2014-03-01

A combined magnetization and zero-field 59Co spin-echo nuclear magnetic resonance (NMR) study has been carried out on one member of a recently developed class of highly ordered mesoporous nanostructured materials, mesoporous Co3O4 (designated UCT-8, University of Connecticut, mesoporous materials). The material was synthesized using one-step soft-templating by an inverse micelles packing approach. Characterization of UCT-8 by powder x-ray diffraction and electron microscopy reveals that the mesostructure consists of random close-packed Co3O4 nanoparticles ≈ 12 nm in diameter. The N2 sorption isotherm for UCT-8, which is type IV with a type H1 hysteresis loop, yields a 134 m2/g BET surface area and a 7.7 nm BJH desorption pore diameter. The effect of heat treatment on the structure is discussed. The antiferromagnetic Co3O4 nanoparticles have a Néel temperature TN = 27 K, somewhat lower than the bulk. A fit to the Curie-Weiss law over the temperature range 75 K ≤ T ≤ 300 K yields an effective magnetic moment of μeff = 4.36 μB for the Co2+ ions, indicative of some orbital contribution, and a Curie-Weiss temperature Θ = -93.5 K, consistent with antiferromagnetic ordering. The inter-sublattice and intra-sublattice exchange constants for the Co2+ ions are J1/kB = (-)4.75 K and J2/kB = (-)0.87 K, respectively, both corresponding to antiferromagnetic coupling. The presence of uncompensated surface spins is observed below TN with shifts in the hysteresis loops, i.e., an exchange-bias effect. The 59Co NMR spectrum for UCT-8, which is attributed to Co2+ ions at the tetrahedral A sites, is asymmetrically broadened with a peak at ≈55 MHz (T = 4.2 K). Since there is cubic symmetry at the A-sites, the broadening is indicative of a magnetic field distribution due to the uncompensated surface spins. The spectrum is consistent with antiferromagnetically ordered particles that are nanometer in size and single domain.

Facile synthesis of mesoporous NiFe2O4/CNTs nanocomposite cathode material for high performance asymmetric pseudocapacitors

NASA Astrophysics Data System (ADS)

Kumar, Nagesh; Kumar, Amit; Huang, Guan-Min; Wu, Wen-Wei; Tseng, Tseung Yuen

2018-03-01

Morphology and synergistic effect of constituents are the two very important factors that greatly influence the physical, chemical and electrochemical properties of a composite material. In the present work, we report the enhanced electrochemical performance of mesoporous NiFe2O4 and multiwall carbon nanotubes (MWCNTs) nanocomposites synthesized via hexamethylene tetramine (HMT) assisted one-pot hydrothermal approach. The synthesized cubic phase spinel NiFe2O4 nanomaterial possesses high specific surface area (148 m2g-1) with narrow mesopore size distribution. The effect of MWCNTs addition on the electrochemical performance of nanocomposite has been probed thoroughly in a normal three electrode configuration using 2 M KOH electrolyte at room temperature. Experimental results show that the addition of mere 5 mg MWCNTs into fixed NiFe2O4 precursors amount enhances the specific capacitance up to 1291 F g-1 at 1 A g-1, which is the highest reported value for NiFe2O4 nanocomposites so far. NiFe2O4/CNT nanocomposite exhibits small relaxation time constant (1.5 ms), good rate capability and capacitance retention of 81% over 500 charge-discharge cycles. This excellent performance can be assigned to high surface area, mesoporous structure of NiFe2O4 and conducting network formed by MWCNTs in the composite. Further, to evaluate the device performance of the composite, an asymmetric pseudocapacitor has been designed using NiFe2O4/CNT nanocomposite as a positive and N-doped graphene as a negative electrode material, respectively. Our designed asymmetric pseudocapacitor gives maximum energy density of 23 W h kg-1 at power density of 872 W kg-1. These promising results assert the potential of synthesized nanocomposite in the development of efficient practical high-capacitive energy storage devices.

A high performance flexible all solid state supercapacitor based on the MnO2 sphere coated macro/mesoporous Ni/C electrode and ionic conducting electrolyte

NASA Astrophysics Data System (ADS)

Zhi, Jian; Reiser, Oliver; Wang, Youfu; Hu, Aiguo

2016-06-01

A high contact resistance between the active materials and the current collector, a low ionic conductivity of the gel electrolyte, and an impenetrable electrode structure are the three major barriers which greatly limit the capacitance of MnO2 in solid state supercapacitors. As a potential solution to these problems, in this work we report a novel electrode for solid state supercapacitors, based on a ternary system composed of hierarchical MnO2 spheres as the active material, macroporous Ni foam as gel penetrable skeletons and an ordered mesoporous carbon (OMC) membrane as the charge-transport accelerating layer. By employing butyl-3-methylimidazolium chloride (BMIMCl) modified gels as the ionic conducting electrolyte, the utilization efficiency of MnO2 on the specific capacitance was enhanced up to 88% of the theoretical value, delivering a volumetric capacitance of 81 F cm-3, which is the highest value among MnO2 based solid state supercapacitors. Moreover, such a flexible device exhibits exceptional volumetric energy and power density (6.6 Wh L-1 and 549 W L-1, based on the whole device volume) combined with a small capacity loss of 8.5% after 6000 cycles under twisting. These encouraging findings unambiguously overcome the energy bottleneck of MnO2 in solid state supercapacitors, and open up a new application of macro/mesoporous materials in flexible devices.A high contact resistance between the active materials and the current collector, a low ionic conductivity of the gel electrolyte, and an impenetrable electrode structure are the three major barriers which greatly limit the capacitance of MnO2 in solid state supercapacitors. As a potential solution to these problems, in this work we report a novel electrode for solid state supercapacitors, based on a ternary system composed of hierarchical MnO2 spheres as the active material, macroporous Ni foam as gel penetrable skeletons and an ordered mesoporous carbon (OMC) membrane as the charge-transport accelerating layer. By employing butyl-3-methylimidazolium chloride (BMIMCl) modified gels as the ionic conducting electrolyte, the utilization efficiency of MnO2 on the specific capacitance was enhanced up to 88% of the theoretical value, delivering a volumetric capacitance of 81 F cm-3, which is the highest value among MnO2 based solid state supercapacitors. Moreover, such a flexible device exhibits exceptional volumetric energy and power density (6.6 Wh L-1 and 549 W L-1, based on the whole device volume) combined with a small capacity loss of 8.5% after 6000 cycles under twisting. These encouraging findings unambiguously overcome the energy bottleneck of MnO2 in solid state supercapacitors, and open up a new application of macro/mesoporous materials in flexible devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02215d

Experimental and numerical validation of the effective medium theory for the B-term band broadening in 1st and 2nd generation monolithic silica columns.

PubMed

Deridder, Sander; Vanmessen, Alison; Nakanishi, Kazuki; Desmet, Gert; Cabooter, Deirdre

2014-07-18

Effective medium theory (EMT) expressions for the B-term band broadening in monolithic silica columns are presented at the whole-column as well as at the mesoporous skeleton level. Given the bi-continuous nature of the monolithic medium, regular as well as inverse formulations of the EMT-expressions have been established. The established expressions were validated by applying them to a set of experimental effective diffusion (Deff)-data obtained via peak parking on a number of 1st and 2nd generation monolithic silica columns, as well as to a set of numerical diffusion simulations in a simplified monolithic column representation (tetrahedral skeleton model) with different external porosities and internal diffusion coefficients. The numerically simulated diffusion data can be very closely represented over a very broad range of zone retention factors (up to k″=80) using the established EMT-expressions, especially when using the inverse variant. The expressions also allow representing the experimentally measured effective diffusion data very closely. The measured Deff/Dmol-values were found to decrease significantly with increasing retention factor, in general going from about Deff/Dmol=0.55 to 0.65 at low k″ (k″≅1.5-3.8) to Deff/Dmol=0.25 at very high k″ (k″≅40-80). These values are significantly larger than observed in fully-porous and core-shell particles. The intra-skeleton diffusion coefficient (Dpz) was typically found to be of the order of Dpz/Dmol=0.4, compared to Dpz/Dmol=0.2-0.35 observed in most particle-based columns. These higher Dpz/Dmol values are the cause of the higher Deff/Dmol values observed. In addition, it also appears that the higher internal diffusion is linked to the higher porosity of the mesoporous skeleton that has a relatively open structure with relatively wide pores. The observed (weak) relation between Dpz/Dmol and the zone retention factor appears to be in good agreement with that predicted when applying the regular variant of the EMT-expression directly to the mesoporous skeleton level. Copyright © 2014 Elsevier B.V. All rights reserved.

The composite capacitive behaviors of the N and S dual doped ordered mesoporous carbon with ultrahigh doping level

NASA Astrophysics Data System (ADS)

Zhang, Deyi; Lei, Longyan; Shang, Yonghua; Wang, Kunjie; Wang, Yi

2016-01-01

Heteroatoms doping provides a promising strategy for improving the energy density of supercapacitors based on the carbon electrodes. In this paper, we present a N and S dual doped ordered mesoporous carbon with ultrahigh doping level using dimethylglyoxime as pristine precursor. The N doping content of the reported materials varies from 6.6 to 15.6 at.% dependent on the carbonization temperature, and the S doping content varies from 0.46 to 1.01 at.%. Due to the ultrahigh heteroatoms doping content, the reported materials exhibit pronounced pseudo-capacitance. Meanwhile, the reported materials exhibit high surface areas (640⿿869 m2 g⿿1), large pore volume (0.71⿿1.08 cm2 g⿿1) and ordered pore structure. The outstanding textual properties endow the reported materials excellent electrical double-layer capacitance (EDLC). By effectively combining the pseudo-capacitance with EDLC, the reported materials exhibit a surprising energy storage/relax capacity with the highest specific capacitance of 565 F g⿿1, which value is 3.3 times higher than that of pristine CMK-3, and can compete against some conventional pseudo-capacitance materials.

Mesoporous Fluorinated Metal-Organic Frameworks with Exceptional Adsorption of Fluorocarbons and CFCs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Teng-Hao; Popov, Ilya; Kaveevivitchai, Watchareeya

2016-02-08

Two mesoporous fluorinated metal–organic frameworks (MOFs) were synthesized from extensively fluorinated tritopic carboxylate- and tetrazolate-based ligands. The tetrazolate-based framework MOFF-5 has an accessible surface area of 2445 m 2g -1, the highest among fluorinated MOFs. Crystals of MOFF-5 adsorb hydrocarbons, fluorocarbons, and chlorofluorocarbons (CFCs)—the latter two being ozone-depleting substances and potent greenhouse species—with weight capacities of up to 225%. The material exhibits an apparent preference for the adsorption of non-spherical molecules, binding unusually low amounts of both tetrafluoromethane and sulfur hexafluoride.

Prevention of bacterial adhesion to zwitterionic biocompatible mesoporous glasses.

PubMed

Sánchez-Salcedo, Sandra; García, Ana; Vallet-Regí, María

2017-07-15

Novel materials, based on Mesoporous Bioactive Glasses (MBGs) in the ternary system SiO 2 -CaO-P 2 O 5 , decorated with (3-aminopropyl)triethoxysilane (APTES) and subsequently with amino acid Lysine (Lys), by post-grafting method on the external surface of the glasses (named MBG-NH 2 and MBG-Lys), are reported. The surface functionalization with organic groups did not damage the mesoporous network and their structural and textural properties were also preserved despite the high solubility of MBG matrices. The incorporation of Lys confers a zwitterionic nature to these MBG materials due to the presence of adjacent amine and carboxylic groups in the external surface. At physiologic pH, this coexistence of basic amine and carboxilic acid groups from anchored Lys provided zero surface charge named zwitterionic effect. This behaviour could give rise to potential applications of antibacterial adhesion. Therefore, in order to assess the influence of zwitterionic nature in in vitro bacterial adhesion, studies were carried out with Staphylococcus aureus. It was demonstrated that the efficient interaction of these zwitterionic pairs onto the MBG surfaces reduced bacterial adhesion up to 99.9% compared to bare MBGs. In order to test the suitability of zwitterionic MBGs materials as bone grafts, their cytocompatibility was investigated in vitro with MC3T3-E1 preosteoblasts. These findings suggested that the proposed surface functionalization strategy provided MBG materials with notable antibacterial adhesion properties, hence making these materials promising candidates for local bone infection therapy. The present research work is focused in finding a preventive treatment of bone infection based on Mesoporous Bioactive Glasses (MBGs) with antibacterial adhesion properties obtained by zwitterionic surface modification. MBGs exhibit unique nanostructural, textural and bioactive characteristics. The novelty and originality of this manuscript is based on the design and optimization of a straightforward functionalization method capable of providing MBGs with zwitterionic surfaces that are able to inhibit bacterial adhesion without affecting their cytocompatibility. This new characteristic enhanced the MBG properties to avoid the bacterial adherence onto the implant surfaces for bone tissue engineering applications. Subsequently, it could help to decrease the infection rates after implantation surgery, which represents one of the most serious complications associated to surgical treatments of bone diseases and fractures. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Mo-doped SnO2 mesoporous hollow structured spheres as anode materials for high-performance lithium ion batteries

NASA Astrophysics Data System (ADS)

Wang, Xuekun; Li, Zhaoqiang; Zhang, Zhiwei; Li, Qun; Guo, Enyan; Wang, Chengxiang; Yin, Longwei

2015-02-01

We designed a facile infiltration route to synthesize mesoporous hollow structured Mo doped SnO2 using silica spheres as templates. It is observed that Mo is uniformly incorporated into SnO2 lattice in the form of Mo6+. The as-prepared mesoporous Mo-doped SnO2 LIBs anodes exhibit a significantly improved electrochemical performance with good cycling stability, high specific capacity and high rate capability. The mesoporous hollow Mo-doped SnO2 sample with 14 at% Mo doping content displays a specific capacity of 801 mA h g-1 after 60 cycles at a current density of 100 mA g-1, about 1.66 times higher than that of the pure SnO2 hollow sample. In addition, even if the current density is as high as 1600 mA g-1 after 60 cycles, it could still retain a stable specific capacity of 530 mA h g-1, exhibiting an extraordinary rate capability. The greatly improved electrochemical performance of the Mo-doped mesoporous hollow SnO2 sample could be attributed to the following factors. The large surface area and hollow structure can significantly enhance structural integrity by acting as mechanical buffer, effectively alleviating the volume changes generated during the lithiation/delithiation process. The incorporation of Mo into the lattice of SnO2 improves charge transfer kinetics and results in a faster Li+ diffusion rate during the charge-discharge process.

Tailored Mesoporous Silicas: From Confinement Effects to Catalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buchanan III, A C; Kidder, Michelle

2010-01-01

Ordered mesoporous silicas continue to find widespread use as supports for diverse applications such as catalysis, separations, and sensors. They provide a versatile platform for these studies because of their high surface area and the ability to control pore size, topology, and surface properties over wide ranges. Furthermore, there is a diverse array of synthetic methodologies for tailoring the pore surface with organic, organometallic, and inorganic functional groups. In this paper, we will discuss two examples of tailored mesoporous silicas and the resultant impact on chemical reactivity. First, we explore the impact of pore confinement on the thermochemical reactivity ofmore » phenethyl phenyl ether (PhCH2CH2OPh, PPE), which is a model of the dominant {beta}-aryl ether linkage present in lignin derived from woody biomass. The influence of PPE surface immobilization, grafting density, silica pore diameter, and presence of a second surface-grafted inert 'spacer' molecule on the product selectivity has been examined. We will show that the product selectivity can be substantially altered compared with the inherent gas-phase selectivity. Second, we have recently initiated an investigation of mesoporous silica supported, heterobimetallic oxide materials for photocatalytic conversion of carbon dioxide. Through surface organometallic chemistry, isolated M-O-M species can be generated on mesoporous silicas that, upon irradiation, form metal to metal charge transfer bands capable of converting CO{sub 2} into CO. Initial results from studies of Ti(IV)-O-Sn(II) on SBA-15 will be presented.« less

General Method for the Synthesis of Hollow Mesoporous Carbon Spheres with Tunable Textural Properties.

PubMed

Mezzavilla, Stefano; Baldizzone, Claudio; Mayrhofer, Karl J J; Schüth, Ferdi

2015-06-17

A versatile synthetic procedure to prepare hollow mesoporous carbon spheres (HMCS) is presented here. This approach is based on the deposition of a homogeneous hybrid polymer/silica composite shell on the outer surface of silica spheres through the surfactant-assisted simultaneous polycondensation of silica and polymer precursors in a colloidal suspension. Such composite materials can be further processed to give hollow mesoporous carbon spheres. The flexibility of this method allows for independent control of the morphological (i.e., core diameter and shell thickness) and textural features of the carbon spheres. In particular, it is demonstrated that the size of the pores within the mesoporous shell can be precisely tailored over an extended range (2-20 nm) by simply adjusting the reaction conditions. In a similar fashion, also the specific carbon surface area as well as the total shell porosity can be tuned. Most importantly, the textural features can be adjusted without affecting the dimension or the morphology of the spheres. The possibility to directly modify the shell textural properties by varying the synthetic parameters in a scalable process represents a distinct asset over the multistep hard-templating (nanocasting) routes. As an exemplary application, Pt nanoparticles were encapsulated in the mesoporous shell of HMCS. The resulting Pt@HMCS catalyst showed an enhanced stability during the oxygen reduction reaction, one of the most important reactions in electrocatalysis. This new synthetic procedure could allow the expansion, perhaps even beyond the lab-scale, of advanced carbon nanostructured supports for applications in catalysis.

Quantitative atomic-scale structure characterization of ordered mesoporous carbon materials by solid state NMR

DOE PAGES

Wang, Zhuoran; Opembe, Naftali; Kobayashi, Takeshi; ...

2018-02-03

In this study, solid-state (SS)NMR techniques were applied to characterize the atomic-scale structures of ordered mesoporous carbon (OMC) materials prepared using Pluronic F127 as template with resorcinol and formaldehyde as polymerizing precursors. A rigorous quantitative analysis was developed using a combination of 13C SSNMR spectra acquired with direct polarization and cross polarization on natural abundant and selectively 13C-enriched series of samples pyrolyzed at various temperatures. These experiments identified and counted the key functional groups present in the OMCs at various stages of preparation and thermal treatment. Lastly, the chemical evolution of molecular networks, the average sizes of aromatic clusters andmore » the extended molecular structures of OMCs were then inferred by coupling this information with the elemental analysis results.« less