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Sample records for mesoporous activated carbon

  1. Studies on Supercapacitor Electrode Material from Activated Lignin-Derived Mesoporous Carbon

    SciTech Connect

    Saha, Dipendu; Li, Yunchao; Bi, Zhonghe; Chen, Jihua; Keum, Jong Kahk; Hensley, Dale K; Grappe, Hippolyte A.; Meyer III, Harry M; Dai, Sheng; Paranthaman, Mariappan Parans; Naskar, Amit K

    2014-01-01

    We synthesized mesoporous carbon from pre-cross-linked lignin gel impregnated with a surfactant as the pore-forming agent, and then activated the carbon through physical and chemical methods to obtain activated mesoporous carbon. The activated mesoporous carbons exhibited 1.5- to 6-fold increases in porosity with a maximum BET specific surface area of 1148 m2/g and a pore volume of 1.0 cm3/g. Slow physical activation helped retain dominant mesoporosity; however, aggressive chemical activation caused some loss of the mesopore volume fraction. Plots of cyclic voltammetric data with the capacitor electrode made from these carbons showed an almost rectangular curve depicting the behavior of ideal double-layer capacitance. Although the pristine mesoporous carbon exhibited the same range of surface-area-based capacitance as that of other known carbon-based supercapacitors, activation decreased the surface-area-based specific capacitance and increased the gravimetric-specific capacitance of the mesoporous carbons. Surface activation lowered bulk density and electrical conductivity. Warburg impedance as a vertical tail in the lower frequency domain of Nyquist plots supported good supercapacitor behavior for the activated mesoporous carbons. Our work demonstrated that biomass-derived mesoporous carbon materials continue to show potential for use in specific electrochemical applications.

  2. 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.

  3. Preparation of activated carbons with mesopores by use of organometallics

    SciTech Connect

    Yamada, Yoshio; Yoshizawa, Noriko; Furuta, Takeshi

    1996-12-31

    Activated carbons are commercially produced by steam or CO{sub 2} activation of coal, coconut shell and so on. In general the carbons obtained give pores with a broad range of distribution. The objective of this study was to prepare activated carbons from coal by use of various organometallic compounds. The carbons were evaluated for pore size by nitrogen adsorption experiments.

  4. A facile synthesis of Fe3C@mesoporous carbon nitride nanospheres with superior electrocatalytic activity.

    PubMed

    Liu, Ben; Yao, Huiqin; Daniels, Robert A; Song, Wenqiao; Zheng, Haoquan; Jin, Lei; Suib, Steven L; He, Jie

    2016-03-01

    We report a colloidal amphiphile-templating approach to preparing nanosized Fe3C encapsulated within mesoporous nitrogen-doped carbon nanospheres (Fe3C@mCN). The obtained Fe3C@mCN hybrids having a high surface area and ultrafine Fe3C nanocrystals exhibited superior activity and durability for oxygen reduction. PMID:26902677

  5. 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.

  6. Mesoporous carbon materials

    DOEpatents

    Dai, Sheng; Wang, Xiqing

    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.

  7. Synthesis of extremely large mesoporous activated carbon and its unique adsorption for giant molecules

    SciTech Connect

    Tamai, Hisashi; Kakii, Takuhiro; Hirota, Yoshifumi

    1996-02-01

    The steam invigoration of pitches (softening points 85 and 280{degrees}C) homogenized with 1-3 wt% of organo rare0earth metal complexes such as Ln(C{sub 5}H{sub 5}){sub 3} or Ln(acac) (Ln=Y, Yb) at 930{degrees}C provided activated carbons with an extremely high mesopore ration, >70%. The resulted activated carbon selectively adsorbs giant molecules such as Vitamin B{sub 12}, blue acid 90 dye, dextran, nystatin, and humic acid, reflecting their large mesopore volumes. To understand what kind of carbon skeleton in pitch is suited for generation of high mesopore ration, the steam invigoration of a series of condensed polynuclear aromatics (COPNA) resins prepared from naphthlene, anthracene, phenanthrene, pyrene, or perylene and p-xylene-{alpha},{alpha}{prime}-diol were conducted in the presence of rare-earth metal complexes. As a result, COPNA resins containing phenanthrene, perylene, and pyrene generated large mesopore volume. 35 refs., 16 figs., 11 tabs.

  8. New route toward building active ruthenium nanoparticles on ordered mesoporous carbons with extremely high stability

    PubMed Central

    Yang, Ying; Sun, Chengjun; Ren, Yang; Hao, Shijie; Jiang, Daqiang

    2014-01-01

    Creating highly active and stable metal catalysts is a persistent goal in the field of heterogeneous catalysis. However, a real catalyst can rarely achieve both of these qualities simultaneously due to limitations in the design of the active site and support. One method to circumvent this problem is to fabricate firmly attached metal species onto the voids of a mesoporous support formed simultaneously. In this study, we developed a new type of ruthenium catalyst that was firmly confined by ordered mesoporous carbons through the fabrication of a cubic Ia3d chitosan-ruthenium-silica mesophase before pyrolysis and silica removal. This facile method generates fine ruthenium nanoparticles (ca. 1.7 nm) that are homogeneously dispersed on a mesoporous carbonaceous framework. This ruthenium catalyst can be recycled 22 times without any loss of reactivity, showing the highest stability of any metal catalysts; this catalyst displays a high activity (23.3 molLAh−1gmetal−1) during the catalytic hydrogenation of levulinic acid (LA) when the metal loading is 6.1 wt%. Even at an ultralow loading (0.3 wt%), this catalyst still outperforms the most active known Ru/C catalyst. This work reveals new possibilities for designing and fabricating highly stable and active metal catalysts by creating metal sites and mesoporous supports simultaneously. PMID:24687047

  9. A facile synthesis of Fe3C@mesoporous carbon nitride nanospheres with superior electrocatalytic activity

    NASA Astrophysics Data System (ADS)

    Liu, Ben; Yao, Huiqin; Daniels, Robert A.; Song, Wenqiao; Zheng, Haoquan; Jin, Lei; Suib, Steven L.; He, Jie

    2016-03-01

    We report a colloidal amphiphile-templating approach to preparing nanosized Fe3C encapsulated within mesoporous nitrogen-doped carbon nanospheres (Fe3C@mCN). The obtained Fe3C@mCN hybrids having a high surface area and ultrafine Fe3C nanocrystals exhibited superior activity and durability for oxygen reduction.We report a colloidal amphiphile-templating approach to preparing nanosized Fe3C encapsulated within mesoporous nitrogen-doped carbon nanospheres (Fe3C@mCN). The obtained Fe3C@mCN hybrids having a high surface area and ultrafine Fe3C nanocrystals exhibited superior activity and durability for oxygen reduction. Electronic supplementary information (ESI) available: Synthetic details, more characterizations and electrocatalytic ORR studies of Fe3C@mCN nanospheres. See DOI: 10.1039/c6nr00604c

  10. Activated graphene-based carbons as supercapacitor electrodes with macro- and mesopores.

    PubMed

    Kim, Taeyoung; Jung, Gyujin; Yoo, Seonmi; Suh, Kwang S; Ruoff, Rodney S

    2013-08-27

    Electric double layer capacitors (or supercapacitors) store charges through the physisorption of electrolyte ions onto porous carbon electrodes. The control over structure and morphology of carbon electrode materials is therefore an effective strategy to render them high surface area and efficient paths for ion diffusion. Here we demonstrate the fabrication of highly porous graphene-derived carbons with hierarchical pore structures in which mesopores are integrated into macroporous scaffolds. The macropores were introduced by assembling graphene-based hollow spheres, and the mesopores were derived from the chemical activation with potassium hydroxide. The unique three-dimensional pore structures in the produced graphene-derived carbons give rise to a Brunauer-Emmett-Teller surface area value of up to 3290 m(2) g(-1) and provide an efficient pathway for electrolyte ions to diffuse into the interior surfaces of bulk electrode particles. These carbons exhibit both high gravimetric (174 F g(-1)) and volumetric (~100 F cm(-3)) specific capacitance in an ionic liquid electrolyte in acetonitrile. The energy density and power density of the cell assembled with this carbon electrode are also high, with gravimetric values of 74 Wh kg(-1) and 338 kW kg(-1) and volumetric values of 44 Wh L(-1) and 199 kW L(-1), respectively. The supercapacitor performance achieved with these graphene-derived carbons is attributed to their unique pore structure and makes them potentially promising for diverse energy storage devices. PMID:23829569

  11. 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.

  12. Aggregation-free gold nanoparticles in ordered mesoporous carbons: toward highly active and stable heterogeneous catalysts.

    PubMed

    Wang, Shuai; Zhao, Qingfei; Wei, Huimin; Wang, Jian-Qiang; Cho, Minhyung; Cho, Hae Sung; Terasaki, Osamu; Wan, Ying

    2013-08-14

    A coordination-assisted synthetic approach is reported here for the synthesis of highly active and stable gold nanoparticle catalysts in ordered mesoporous carbon materials using triblock copolymer F127 as a structure-directing agent, thiol-containing silane as a coordination agent, HAuCl4 as a gold source, and phenolic resin as a carbon source. Upon carbonization, the gold precursor becomes reduced to form monodispersed Au nanoparticles of ca. 9.0 nm, which are entrapped or confined by the "rigid" mesoporous carbonaceous framework. Nanoparticle aggregation is inhibited even at a high temperature of 600 °C. After removal of the silica component, the materials possess the ordered mesostructure, high surface area (~1800 m(2)/g), large pore volume (~1.19 cm(3)/g), and uniform bimodal mesopore size (<2.0 and 4.0 nm). The monodispersed gold nanoparticles are highly exposed because of the interpenetrated bimodal pores in the carbon framework, which exhibit excellent catalytic performance. A completely selective conversion of benzyl alcohol in water to benzoic acid can be achieved at 90 °C and 1 MPa oxygen. Benzyl alcohol can also be quantitatively converted to benzoic acid at 60 °C even under an atmospheric pressure, showing great advantages in green chemistry. The catalysts are stable, poison resistant, and reusable with little activity loss due to metal leaching. The silane coupling agent played several functions in this approach: (1) coordinating with gold species by the thiol group to benefit formation of monodispersed Au nanoparticles; (2) reacting with phenolic resins by silanol groups to form relatively "rigid" composite framework; (3) pore-forming agent to generate secondary pores in carbon pore walls, which lead to higher surface area, larger pore volumes, and higher accessibility to to the gold nanoparticles. Complete removal of the silica component proves to have little effect on the catalytic performance of entrapped Au nanoparticles. PMID:23865622

  13. Platinum/mesoporous WO3 as a carbon-free electrocatalyst with enhanced electrochemical activity for methanol oxidation.

    PubMed

    Cui, Xiangzhi; Shi, Jianlin; Chen, Hangrong; Zhang, Lingxia; Guo, Limin; Gao, Jianhua; Li, Jingbo

    2008-09-25

    A new type of carbon-free electrode catalyst, Pt/mesoporous WO3 composite, has been prepared and its electrochemical activity for methanol oxidation has been investigated. The mesoporous tungsten trioxide support was synthesized by a replicating route and the mesoporous composties with Pt loaded were characterized by using X-ray diffraction (XRD), nitrogen sorption, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) techniques. Cyclic voltammetry (CV), line scan voltammetry (LSV) and chronoamperometry (CA) were adopted to characterize the electrochemical activities of the composites. The mesoporous WO3 showed high surface area, ordered pore structure, and nanosized wall thickness of about 6-7 nm. When a certain amount of Pt nanoparticles were dispersed in the pore structure of mesoporous WO3, the resultant mesostructured Pt/WO3 composites exhibit high electro-catalytic activity toward methanol oxidation. The overall electro-catalytic activities of 20 wt % Pt/WO3 composites are significantly higher than that of commercial 20 wt % Pt/C catalyst and are comparable to the 20 wt % PtRu/C catalyst in the potential region of 0.5-0.7 V. The enhanced electro-catalytic activity is attributed to be resulted from the assistant catalytic effect and the mesoporous structure of WO3 supports. PMID:18754636

  14. Ordered mesoporous porphyrinic carbons with very high electrocatalytic activity for the oxygen reduction reaction

    PubMed Central

    Cheon, Jae Yeong; Kim, Taeyoung; Choi, YongMan; Jeong, Hu Young; Kim, Min Gyu; Sa, Young Jin; Kim, Jaesik; Lee, Zonghoon; Yang, Tae-Hyun; Kwon, Kyungjung; Terasaki, Osamu; Park, Gu-Gon; Adzic, Radoslav R.; Joo, Sang Hoon

    2013-01-01

    The high cost of the platinum-based cathode catalysts for the oxygen reduction reaction (ORR) has impeded the widespread application of polymer electrolyte fuel cells. We report on a new family of non-precious metal catalysts based on ordered mesoporous porphyrinic carbons (M-OMPC; M = Fe, Co, or FeCo) with high surface areas and tunable pore structures, which were prepared by nanocasting mesoporous silica templates with metalloporphyrin precursors. The FeCo-OMPC catalyst exhibited an excellent ORR activity in an acidic medium, higher than other non-precious metal catalysts. It showed higher kinetic current at 0.9 V than Pt/C catalysts, as well as superior long-term durability and MeOH-tolerance. Density functional theory calculations in combination with extended X-ray absorption fine structure analysis revealed a weakening of the interaction between oxygen atom and FeCo-OMPC compared to Pt/C. This effect and high surface area of FeCo-OMPC appear responsible for its significantly high ORR activity. PMID:24056308

  15. Highly basic CaO nanoparticles in mesoporous carbon materials and their excellent catalytic activity.

    PubMed

    Raja, Pradeep Kumar; Chokkalingam, Anand; Priya, Subramaniam V; Balasubramanian, Veerappan V; Benziger, Mercy R; Aldeyab, Salem S; Jayavell, Ramasamy; Ariga, Katsukiho; Vinu, Ajayan

    2012-06-01

    Highly basic CaO nanoparticles immobilized mesoporous carbon materials (CaO-CMK-3) with different pore diameters have been successfully prepared by using wet-impregnation method. The prepared materials were subjected to extensive characterization studies using sophisticated techniques such as XRD, nitrogen adsorption, HRSEM-EDX, HRTEM and temperature programmed desorption of CO2 (TPD of CO2). The physico-chemical characterization results revealed that these materials possess highly dispersed CaO nanoparticles, excellent nanopores with well-ordered structure, high specific surface area, large specific pore volume, pore diameter and very high basicity. We have also demonstrated that the basicity of the CaO-CMK-3 samples can be controlled by simply varying the amount of CaO loading and pore diameter of the carbon support. The basic catalytic performance of the samples was investigated in the base-catalyzed transesterification of ethylacetoacetate by aryl, aliphatic and cyclic primary alcohols. CMK-3 catalyst with higher CaO loading and larger pore diameter was found to be highly active with higher conversion within a very short reaction time. The activity of 30% CaO-CMK3-150 catalyst for transesterification of ethylacetoacetate using different alcohols increases in the following order: octanol > butanol > cyclohexanol > benzyl alcohol > furfuryl alcohol. PMID:22905508

  16. 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.

  17. Mesoporous carbonates and method of making

    SciTech Connect

    Fryxell, Glen; Liu, Jun; Zemanian, Thomas S.

    2004-06-15

    Mesoporous metal carbonate structures are formed by providing a solution containing a non-ionic surfactant and a calcium acetate salt, adding sufficient base to react with the acidic byproducts to be formed by the addition of carbon dioxide, and adding carbon dioxide, thereby forming a mesoporous metal carbonate structure containing the metal from said metal salt.

  18. Characterization and performance evaluation of an innovative mesoporous activated carbon used for drinking water purification in comparison with commercial carbons.

    PubMed

    Gong, Xu-Jin; Li, Wei-Guang; Wang, Guang-Zhi; Zhang, Duo-Ying; Fan, Wen-Biao; Yin, Zhao-Dong

    2015-09-01

    The preparation, characterization, and performance evaluation of an innovative mesoporous activated carbon (C-XHIT) were conducted in this study. Comparative evaluation with commercial carbons (C-PS and C-ZJ15) and long-term performance evaluation of C-XHIT were conducted in small-scale system-A (S-A) and pilot-scale system-B (S-B-1 and S-B-2 in series), respectively, for treating water from Songhua River. The cumulative uptake of micropollutants varied with KBV (water volume fed to columns divided by the mass of carbons, m(3) H2O/kg carbon) was employed in the performance evaluation. The results identified that mesoporous and microporous volumes were simultaneously well-developed in C-XHIT. Higher mesoporosity (63.94 %) and average pore width (37.91 Å) of C-XHIT ensured a higher adsorption capacity for humic acid compared to C-PS and C-ZJ15. When the KBV of S-A reached 12.58 m(3) H2O/kg carbon, cumulative uptake of organic pollutants achieved by C-XHIT increased by 32.82 and 156.29 % for DOC (QC) and 22.53 and 112.48 % for UV254 (QUV) compared to C-PS and C-ZJ15, respectively; in contrast, the adsorption capacity of NH4 (+)-N did not improve significantly. C-XHIT achieved high average removal efficiencies for DOC (77.43 ± 16.54 %) and UV254 (83.18 ± 13.88 %) in S-B over 253 days of operation (KBV = 62 m(3) H2O/kg carbon). Adsorption dominated the removal of DOC and UV254 in the initial phases of KBV (0-15 m(3) H2O/kg carbon), and simultaneous biodegradation and adsorption were identified as the mechanisms for organic pollutant uptake at KBV above 25 m(3) H2O/kg carbon. The average rates contributed by S-B-1 and S-B-2 for QC and QUV were approximately 0.75 and 0.25, respectively. Good linear and exponential correlations were observed between S-A and S-B in terms of QC and QUV obtained by C-XHIT, respectively, for the same KBV ranges, indicating a rapid and cost-saving evaluation method. The linear correlation between mesoporosity and QC (QUV) was also identified by the evolution of the property indices of C-XHIT. PMID:25940491

  19. Activated mesoporous carbon nanofibers fabricated using water etching-assisted templating for high-performance electrochemical capacitors.

    PubMed

    An, Geon-Hyoung; Koo, Bon-Ryul; Ahn, Hyo-Jin

    2016-03-01

    Activated mesoporous carbon nanofibers (AMCNFs) are synthesized by a sequential process of electrospinning, water etching-assisted templating, and acid treatment. Their morphologies, crystal structures, melting behavior, chemical bonding states, surface properties, and electrochemical performance are investigated for three different polyacrylonitrile (PAN) to polyvinylpyrrolidone (PVP) weight ratios - PAN : PVP = 8 : 2, 7 : 3, and 6 : 4. Compared to other samples, the AMCNFs with an optimum weight ratio of 6 : 4 show the highest specific surface area of 692 m(2) g(-1), a high volume percentage of mesopores of 43.9%, and an increased amount of carboxyl groups (10.5%). This results in a high specific capacitance of 207 F g(-1), a high-rate capability with a capacitance retention of 93%, a high energy density of 24.8-23.1 W h kg(-1), and an excellent cycling durability of up to 3000 cycles. The electrochemical performance improvement can be explained by the combined effect of the high surface area relative to the increased electrical double-layers, the high volume fraction of mesopores relative to shorter diffusion routes and low resistance pathways for ions, and the increased amount of carboxyl groups on the CNF surface relative to enhanced wettability. PMID:26866359

  20. Electrochemically active, crystalline, mesoporous covalent organic frameworks on carbon nanotubes for synergistic lithium-ion battery energy storage

    NASA Astrophysics Data System (ADS)

    Xu, Fei; Jin, Shangbin; Zhong, Hui; Wu, Dingcai; Yang, Xiaoqing; Chen, Xiong; Wei, Hao; Fu, Ruowen; Jiang, Donglin

    2015-02-01

    Organic batteries free of toxic metal species could lead to a new generation of consumer energy storage devices that are safe and environmentally benign. However, the conventional organic electrodes remain problematic because of their structural instability, slow ion-diffusion dynamics, and poor electrical conductivity. Here, we report on the development of a redox-active, crystalline, mesoporous covalent organic framework (COF) on carbon nanotubes for use as electrodes; the electrode stability is enhanced by the covalent network, the ion transport is facilitated by the open meso-channels, and the electron conductivity is boosted by the carbon nanotube wires. These effects work synergistically for the storage of energy and provide lithium-ion batteries with high efficiency, robust cycle stability, and high rate capability. Our results suggest that redox-active COFs on conducting carbons could serve as a unique platform for energy storage and may facilitate the design of new organic electrodes for high-performance and environmentally benign battery devices.

  1. A comparative investigation on adsorption performances of mesoporous activated carbon prepared from waste rubber tire and activated carbon for a hazardous azo dye--Acid Blue 113.

    PubMed

    Gupta, V K; Gupta, Bina; Rastogi, Arshi; Agarwal, Shilpi; Nayak, Arunima

    2011-02-15

    A mesoporous carbon developed from waste tire rubber, characterized by chemical analysis, FTIR, and SEM studies, was used as an adsorbent for the removal and recovery of a hazardous azo dye, Acid Blue 113. Surface area, porosity, and density were determined. The adsorption of the dye over the prepared adsorbent and a commercial activated carbon was achieved under different pH, adsorbate concentration, sieve size, adsorbent dosage, contact time and temperature conditions. Langmuir and Freundlich adsorption isotherm models were applied and thermodynamic parameters were calculated. Kinetic studies indicated that the adsorption process follow first order kinetics and particle diffusion mechanisms are operative. By percolating the dye solution through fixed-bed columns the bulk removal of the Acid Blue 113 was carried out and necessary parameters were determined to find out the percentage saturation of both the columns. Recovery of the dye was made by eluting 0.1 M NaOH through the column. PMID:21163571

  2. Mesoporous carbon-supported Pd nanoparticles with high specific surface area for cyclohexene hydrogenation: Outstanding catalytic activity of NaOH-treated catalysts

    NASA Astrophysics Data System (ADS)

    Puskás, R.; Varga, T.; Grósz, A.; Sápi, A.; Oszkó, A.; Kukovecz, Á.; Kónya, Z.

    2016-06-01

    Extremely high specific surface area mesoporous carbon-supported Pd nanoparticle catalysts were prepared with both impregnation and polyol-based sol methods. The silica template used for the synthesis of mesoporous carbon was removed by both NaOH and HF etching. Pd/mesoporous carbon catalysts synthesized with the impregnation method has as high specific surface area as 2250 m2/g. In case of NaOH-etched impregnated samples, the turnover frequency of cyclohexene hydrogenation to cyclohexane at 313 K was obtained ~ 14 molecules • site- 1 • s- 1. The specific surface area of HF-etched samples was higher compared to NaOH-etched samples. However, catalytic activity was ~ 3-6 times higher on NaOH-etched samples compared to HF-etched samples, which can be attributed to the presence of sodium and surface hydroxylgroups of the catalysts etched with NaOH solution.

  3. Graphitic mesoporous carbon based on aromatic polycondensation as catalyst support for oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Kong, Jiangrong; Liu, Yaru; Liu, Qicheng; Zhu, Hongze

    2015-03-01

    Mesoporous carbon is constructed by monolithic polyaromatic mesophase deriving from the hexane insoluble of coal-tar pitch. This carbon material exhibits spherical morphology and layered crystallite, and thereby can be graphitized at 900 °C without destroying the mesoporous structure. Electrochemical measurements indicate that graphitic mesoporous carbon (GMC) support not only improves the activity of Pt electrocatalyst to oxygen reduction reaction (ORR), but also shows higher corrosion resistance than commercial XC-72 carbon black in the acid cathode environment.

  4. Electrochemically active, crystalline, mesoporous covalent organic frameworks on carbon nanotubes for synergistic lithium-ion battery energy storage.

    PubMed

    Xu, Fei; Jin, Shangbin; Zhong, Hui; Wu, Dingcai; Yang, Xiaoqing; Chen, Xiong; Wei, Hao; Fu, Ruowen; Jiang, Donglin

    2015-01-01

    Organic batteries free of toxic metal species could lead to a new generation of consumer energy storage devices that are safe and environmentally benign. However, the conventional organic electrodes remain problematic because of their structural instability, slow ion-diffusion dynamics, and poor electrical conductivity. Here, we report on the development of a redox-active, crystalline, mesoporous covalent organic framework (COF) on carbon nanotubes for use as electrodes; the electrode stability is enhanced by the covalent network, the ion transport is facilitated by the open meso-channels, and the electron conductivity is boosted by the carbon nanotube wires. These effects work synergistically for the storage of energy and provide lithium-ion batteries with high efficiency, robust cycle stability, and high rate capability. Our results suggest that redox-active COFs on conducting carbons could serve as a unique platform for energy storage and may facilitate the design of new organic electrodes for high-performance and environmentally benign battery devices. PMID:25650133

  5. Electrochemically active, crystalline, mesoporous covalent organic frameworks on carbon nanotubes for synergistic lithium-ion battery energy storage

    PubMed Central

    Xu, Fei; Jin, Shangbin; Zhong, Hui; Wu, Dingcai; Yang, Xiaoqing; Chen, Xiong; Wei, Hao; Fu, Ruowen; Jiang, Donglin

    2015-01-01

    Organic batteries free of toxic metal species could lead to a new generation of consumer energy storage devices that are safe and environmentally benign. However, the conventional organic electrodes remain problematic because of their structural instability, slow ion-diffusion dynamics, and poor electrical conductivity. Here, we report on the development of a redox-active, crystalline, mesoporous covalent organic framework (COF) on carbon nanotubes for use as electrodes; the electrode stability is enhanced by the covalent network, the ion transport is facilitated by the open meso-channels, and the electron conductivity is boosted by the carbon nanotube wires. These effects work synergistically for the storage of energy and provide lithium-ion batteries with high efficiency, robust cycle stability, and high rate capability. Our results suggest that redox-active COFs on conducting carbons could serve as a unique platform for energy storage and may facilitate the design of new organic electrodes for high-performance and environmentally benign battery devices. PMID:25650133

  6. Highly Ordered Mesoporous Cobalt-Containing Oxides: Structure, Catalytic Properties, and Active Sites in Oxidation of Carbon Monoxide.

    PubMed

    Gu, Dong; Jia, Chun-Jiang; Weidenthaler, Claudia; Bongard, Hans-Josef; Spliethoff, Bernd; Schmidt, Wolfgang; Schüth, Ferdi

    2015-09-01

    Co3O4 with a spinel structure is a very active oxide catalyst for the oxidation of CO. In such catalysts, octahedrally coordinated Co(3+) is considered to be the active site, while tetrahedrally coordinated Co(2+) is assumed to be basically inactive. In this study, a highly ordered mesoporous CoO has been prepared by H2 reduction of nanocast Co3O4 at low temperature (250 °C). The as-prepared CoO material, which has a rock-salt structure with a single Co(2+) octahedrally coordinated by lattice oxygen in Fm3̅m symmetry, exhibited unexpectedly high activity for CO oxidation. Careful investigation of the catalytic behavior of mesoporous CoO catalyst led to the conclusion that the oxidation of surface Co(2+) to Co(3+) causes the high activity. Other mesoporous spinels (CuCo2O4, CoCr2O4, and CoFe2O4) with different Co species substituted with non/low-active metal ions were also synthesized to investigate the catalytically active site of cobalt-based catalysts. The results show that not only is the octahedrally coordinated Co(3+) highly active but also the octahedrally coordinated Co(2+) species in CoFe2O4 with an inverse spinel structure shows some activity. These results suggest that the octahedrally coordinated Co(2+) species is easily oxidized and shows high catalytic activity for CO oxidation. PMID:26301797

  7. Mesoporous carbon nanomaterials as environmental adsorbents.

    PubMed

    Tripathi, Pranav K; Gan, Lihua; Liu, Mingxian; Rao, Nageswara N

    2014-02-01

    The transportation and diffusion of the guest objects or molecules in the porous carbon nanomaterials can be facilitated by reducing the pathway and resistance. The reduced pathway depends on the porous nature of carbon nanomaterials. Classification of porous carbon materials by the International Union of Pure and Applied Chemistry (IUPAC) has given a new opportunity to design the pores as per their applicability and to understand the mobility of ions, atoms, and molecules in the porous network of carbon materials and also advanced their countless applicability. However, synthesis of carbon nanomaterials with a desired porous network is still a great challenge. Although, remarkable developments have taken place in the recent years, control over the pores size and/or hierarchical porous architectures, especially in the synthesis of carbon nanospheres (CNSs) and ordered mesoporous carbon (OMCs) is still intriguing. The micro and mesoporous CNSs and OMCs have been prepared by a variety of procedures and over a wide range of compositions using various different surfactant templates and carbon precursors etc. The mechanisms of formation of micromesopore in the CNSs and OMCs are still evolving. On the other hand, the urge for adsorbents with very high adsorption capacities for removing contaminants from water is growing steadily. In this review, we address the state-of-the-art synthesis of micro and mesoporous CNSs and OMCs, giving examples of their applications for adsorptive removals of contaminants including our own research studies. PMID:24749459

  8. A V2O3-ordered mesoporous carbon composite with novel peroxidase-like activity towards the glucose colorimetric assay

    NASA Astrophysics Data System (ADS)

    Han, Lei; Zeng, Lingxing; Wei, Mingdeng; Li, Chang Ming; Liu, Aihua

    2015-07-01

    It is of great scientific and practical significance to explore inorganic mimetic enzymes to replace natural enzymes due to their instability and high cost. Herein we present an interesting discovery that a V2O3-ordered mesoporous carbon composite (V2O3-OMC) has a novel peroxidase-like activity towards fast redox reaction of typical peroxidase substrates H2O2 and 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS). Due to the small size effect and large surface area of V2O3 nanoparticles supported by OMC, V2O3-OMC exhibited excellent catalytic performance with a kcat of 1.28 × 104 s-1, KM (ABTS) of 0.067 mM and KM (H2O2) of 0.16 mM, and a significantly higher catalytic efficiency (kcat/KM) towards the oxidation of ABTS in comparison with the natural peroxidases. Furthermore, the Ping-pong BiBi mechanism was proposed to explain the catalytic reaction by V2O3-OMC. Based on this highly active biomimetic peroxidase and the colorimetric detection of H2O2, a facile analytical method was developed to detect glucose by using V2O3-OMC and glucose oxidase, which had a wide linear range (0.01-4 mM glucose), good selectivity and reliability for successful detection of various real samples. Thus, the novel V2O3-OMC peroxidase mimetic holds great promise for broad potential applications.It is of great scientific and practical significance to explore inorganic mimetic enzymes to replace natural enzymes due to their instability and high cost. Herein we present an interesting discovery that a V2O3-ordered mesoporous carbon composite (V2O3-OMC) has a novel peroxidase-like activity towards fast redox reaction of typical peroxidase substrates H2O2 and 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS). Due to the small size effect and large surface area of V2O3 nanoparticles supported by OMC, V2O3-OMC exhibited excellent catalytic performance with a kcat of 1.28 × 104 s-1, KM (ABTS) of 0.067 mM and KM (H2O2) of 0.16 mM, and a significantly higher catalytic efficiency (kcat/KM) towards the oxidation of ABTS in comparison with the natural peroxidases. Furthermore, the Ping-pong BiBi mechanism was proposed to explain the catalytic reaction by V2O3-OMC. Based on this highly active biomimetic peroxidase and the colorimetric detection of H2O2, a facile analytical method was developed to detect glucose by using V2O3-OMC and glucose oxidase, which had a wide linear range (0.01-4 mM glucose), good selectivity and reliability for successful detection of various real samples. Thus, the novel V2O3-OMC peroxidase mimetic holds great promise for broad potential applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02694f

  9. A V?O?-ordered mesoporous carbon composite with novel peroxidase-like activity towards the glucose colorimetric assay.

    PubMed

    Han, Lei; Zeng, Lingxing; Wei, Mingdeng; Li, Chang Ming; Liu, Aihua

    2015-07-21

    It is of great scientific and practical significance to explore inorganic mimetic enzymes to replace natural enzymes due to their instability and high cost. Herein we present an interesting discovery that a V2O3-ordered mesoporous carbon composite (V2O3-OMC) has a novel peroxidase-like activity towards fast redox reaction of typical peroxidase substrates H2O2 and 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS). Due to the small size effect and large surface area of V2O3 nanoparticles supported by OMC, V2O3-OMC exhibited excellent catalytic performance with a k(cat) of 1.28 10(4) s(-1), K(M) (ABTS) of 0.067 mM and K(M) (H2O2) of 0.16 mM, and a significantly higher catalytic efficiency (k(cat)/K(M)) towards the oxidation of ABTS in comparison with the natural peroxidases. Furthermore, the Ping-pong BiBi mechanism was proposed to explain the catalytic reaction by V2O3-OMC. Based on this highly active biomimetic peroxidase and the colorimetric detection of H2O2, a facile analytical method was developed to detect glucose by using V2O3-OMC and glucose oxidase, which had a wide linear range (0.01-4 mM glucose), good selectivity and reliability for successful detection of various real samples. Thus, the novel V2O3-OMC peroxidase mimetic holds great promise for broad potential applications. PMID:26099042

  10. Adsorption of 2,4-dichlorophenoxyacetic acid by mesoporous activated carbon prepared from H3PO4-activated langsat empty fruit bunch.

    PubMed

    Njoku, V O; Islam, Md Azharul; Asif, M; Hameed, B H

    2015-05-01

    The removal of toxic herbicide from wastewater is challenging due to the availability of suitable adsorbents. The Langsat empty fruit bunch is an agricultural waste and was used in this study as a cheap precursor to produce activated carbon for the adsorption of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) at different initial concentrations ranging from 50 to 400 mg/L. The produced Langsat empty fruit bunch activated carbon (LEFBAC) was mesoporous and had high surface area of 1065.65 m(2)/g with different active functional groups. The effect of shaking time, temperature and pH on 2,4-D removal were investigated using the batch technique. The adsorption capacity of 2,4-D by LEFBAC was decreased with increase in pH of solution whereas adsorption capacity increased with temperature. The adsorption data was well described by Langmuir isotherm followed by removal capacity of 261.2 mg/g at 30 °C. The results from this work showed that LEFBAC can be used as outstanding material for anionic herbicide uptake from wastewater. PMID:25721981

  11. Direct template synthesis of mesoporous carbon and its application to supercapacitor electrodes

    SciTech Connect

    Yoon, Songhun; Oh, Seung M.; Lee, Chulwee

    2009-08-05

    A direct templating method which is facile, inexpensive and suitable for the large scale production of mesoporous carbon is reported herein. A meso-structure surfactant/silicate template was made in a solution phase and resorcinol-formaldehyde as a carbon precursor was incorporated into the template solution. After aging, carbonization and hydrofluoric acid (HF) etching, mesoporous carbon was obtained. Using X-ray diffraction, scanning and transmission electron microscopy and nitrogen sorption, the synthesis mechanism of the mesoporous carbon was elucidated. According to the small angle X-ray scattering measurements, the surface became smoother after the removal of the silica, indicating that the silica was mostly located at the pore surface of the carbon. Also, the calculation of the pore volume demonstrated that the silica was transferred into the pores of the carbon without structural collapse during HF etching. When the prepared mesoporous carbon was applied to a supercapacitor electrode, the rectangular shape of the cyclic voltammogram was less collapsed, even at a high scan rate, which is indicative of its high rate capability. This was due to the low resistance of the electrolyte in the pores (3.8 {Omega} cm{sup 2}), which was smaller than that of conventional activated carbon electrodes and even comparable to that of ordered mesoporous carbon electrodes. This improved performance was probably due to the well developed mesoporosity and high pore connectivity of the prepared mesoporous carbon.

  12. Phosphorylated Mesoporous Carbon as a Solid Acid Catalyst

    SciTech Connect

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

    2011-01-01

    Mesoporous carbon catalyst supports are attractive due to their wide chemical stability while potentially increasing masstransport through and providing a path for larger molecules to access catalytic sites. Herein we report the synthesis of a 10 phosphorylated mesoporous carbon solid-acid catalyst characterized by NH3-TPD and isopropanol dehydration.

  13. Preparation of free-standing high quality mesoporous carbon membranes

    SciTech Connect

    Wang, Xiqing; Liang, Chengdu; Dai, Sheng; Mahurin, Shannon Mark; Zhu, Qing

    2010-01-01

    Flat-sheet mesoporous carbon membranes with uniform pore size (e.g., 6.4 nm) and controllable thickness were prepared by pyrolysis of polymeric composite films, which were formed by self-assembly of phenolic resin and block copolymer under acidic conditions. Hexamethylenetetramine was selected as a solid cross-linker to control the rheology of polymeric carbon precursors so that the flat-sheet polymeric films could undergo carbonization without deformation, ensuring the preparation of mesoporous carbon membranes on a large scale with high quality. Gas transport properties through these mesoporous carbon membranes are also reported.

  14. Adsorption-desorption characteristics of phenol and reactive dyes from aqueous solution on mesoporous activated carbon prepared from waste tires.

    PubMed

    Tanthapanichakoon, W; Ariyadejwanich, P; Japthong, P; Nakagawa, K; Mukai, S R; Tamon, H

    2005-04-01

    Liquid-phase adsorption-desorption characteristics and ethanol regeneration efficiency of an activated carbon prepared from waste tires and a commercial activated carbon were investigated. Water vapor adsorption experiments reveal that both activated carbons showed hydrophobic surface characteristics. Adsorption experiments reveal that the prepared activated carbon possessed comparable phenol adsorption capacity as the commercial one but clearly larger adsorption capacity of two reactive dyes, Black 5 and Red 31. It was ascertained that the prepared activated carbon exhibited less irreversible adsorption of phenol and the two dyes than its commercial counterpart. Moreover, ethanol regeneration efficiency of the prepared AC saturated with either dye was higher than that of the commercial AC. Because of its superior liquid-phase adsorption-desorption characteristics as well as higher ethanol regeneration efficiency, the prepared activated carbon is more suitable for wastewater treatment, especially for adsorbing similarly bulky adsorbates. PMID:15862334

  15. Cobalt- and iron-based nanoparticles hosted in SBA-15 mesoporous silica and activated carbon from biomass: Effect of modification procedure

    NASA Astrophysics Data System (ADS)

    Tsoncheva, Tanya; Genova, Izabela; Paneva, Daniela; Dimitrov, Momtchil; Tsyntsarski, Boyko; Velinov, Nicolay; Ivanova, Radostina; Issa, Gloria; Kovacheva, Daniela; Budinova, Temenujka; Mitov, Ivan; Petrov, Narzislav

    2015-10-01

    Ordered mesoporous silica of SBA-15 type and activated carbon, prepared from waste biomass (peach stones), are used as host matrix of nanosized iron and cobalt particles. The effect of preparation procedure on the state of loaded nanoparticles is in the focus of investigation. The obtained materials are characterized by Boehm method, low temperature physisorption of nitrogen, XRD, UV-Vis, FTIR, Mossbauer spectroscopy and temperature programmed reduction with hydrogen. The catalytic behaviour of the samples is tested in methanol decomposition. The dispersion, oxidative state and catalytic behaviour of loaded cobalt and iron nanoparticles are successfully tuned both by the nature of porous support and the metal precursor used during the samples preparation. Facile effect of active phase deposition from aqueous solution of nitrate precursors is assumed for activated carbon support. For the silica based materials the catalytic activity could be significantly improved when cobalt acetylacetonate is used during the modification. The complex effect of pore topology and surface functionality of different supports on the active phase formation is discussed.

  16. Synthesis of Ordered Mesoporous Carbon Materials by Dry Etching.

    PubMed

    Nickel, Winfried; Oschatz, Martin; Rico-Francs, Soledad; Klosz, Stefan; Biemelt, Tim; Mondin, Giovanni; Eychmller, Alexander; Silvestre-Albero, Joaqun; Kaskel, Stefan

    2015-10-12

    A novel synthesis method for ordered mesoporous carbons is presented. The inverse replication of a silica template was achieved using the carbonization of sucrose within mesoporous KIT-6. Instead of liquid acid etching, as in classical nanocasting, a novel dry chlorine etching procedure for template removal is presented for the first time. The resultant ordered mesostructured carbon material outperforms carbons obtained by conventional hard templating with respect to high specific micro- and mesopore volumes (0.6 and 1.6 cm(3) g(-1) , respectively), due to the presence of a hierarchical pore system. A high specific surface area of 1671 m(2) g(-1) was achieved, rendering this synthesis route a highly convenient method to produce ordered mesoporous carbons. PMID:26306833

  17. Co@Co3O4 core-shell particle encapsulated N-doped mesoporous carbon cage hybrids as active and durable oxygen-evolving catalysts.

    PubMed

    Li, Xinzhe; Fang, Yiyun; Wen, Lixin; Li, Feng; Yin, Guanlin; Chen, Wanmin; An, Xingcai; Jin, Jun; Ma, Jiantai

    2016-04-01

    Cobalt-based nanomaterials are promising candidates as efficient, affordable, and sustainable alternative electrocatalysts for the oxygen evolution reaction (OER). However, the catalytic efficiency of traditional nanomaterials is still far below what is expected, because of their low stability in basic solutions and poor active site exposure yield. Here a unique hybrid nanomaterial comprising Co@Co3O4 core-shell nanoparticle (NP) encapsulated N-doped mesoporous carbon cages on reduced graphene oxide (denoted as Co@Co3O4@NMCC/rGO) is successfully synthesized via a carbonization and subsequent oxidation strategy of a graphene oxide (GO)-based metal-organic framework (MOF). Impressively, the special carbon cage structure is very important for not only leading to a large active surface area, enhanced mass/charge transport capability, and easy release of gas bubbles, but also preventing Co@Co3O4 NPs from aggregation and peeling off during prolonged electrochemical reactions. As a result, in alkaline media, the resulting hybrid materials catalyze the OER with a low onset potential of ∼1.50 V (vs. RHE) and an over-potential of only 340 mV to achieve a stable current density of 10 mA cm(-2) for at least 25 h. In addition, metallic Co cores in Co@Co3O4 provide an alternative way for electron transport and accelerate the OER rate. PMID:26914166

  18. Mesoporous Carbon for Capacitive Deionization of Saline Water

    SciTech Connect

    Tsouris, Costas; Mayes, Richard T; Kiggans, Jim; Sharma, Ms. Ketki; Yiacoumi, Sotira; DePaoli, David W; Dai, Sheng

    2011-01-01

    Self-assembled mesoporous carbon (MC) materials have been synthesized and tested for application in capacitive deionization (CDI) of saline water. MC was prepared by self-assembly of a triblock copolymer with hydrogen-bonded chains via a phenolic resin, such as resorcinol or phloroglucinol in acidic conditions, followed by carbonization and, in some cases, activation by KOH. Carbon synthesized in this way was ground into powder, from which activated MC sheets were produced. In a variation of this process, after the reaction of triblock copolymer with resorcinol or phloroglucinol, the gel that was formed was used to coat a graphite plate and then carbonized. The coated graphite plate in this case was not activated and was tested to serve as current collector during the CDI process. The performance of these MC materials was compared to that of carbon aerogel for salt concentrations ranging between 1000 ppm and 35,000 ppm. Resorcinol-based MC removed up to 15.2 mg salt per gram of carbon, while carbon aerogel removed 5.8 mg salt per gram of carbon. Phloroglucinol-based MC-coated graphite exhibited the highest ion removal capacity at 21 mg of salt per gram of carbon for 35,000 ppm salt concentration.

  19. Carbon dioxide capture using polyethylenimine-loaded mesoporous carbons.

    PubMed

    Wang, Jitong; Chen, Huichao; Zhou, Huanhuan; Liu, Xiaojun; Qiao, Wenming; Long, Donghui; Ling, Licheng

    2013-01-01

    A high efficiency sorbent for CO2 capture was developed by loading polyethylenimine (PEI) on mesoporous carbons which possessed well-developed mesoporous structures and large pore volume. The physicochemical properties of the sorbent were characterized by N2 adsorption/desorption, scanning electron microscopy (SEM), thermal gravimetric analysis (TG) and Fourier transform infrared spectroscopy (FT-IR) techniques followed by testing for CO2 capture. Factors that affected the sorption capacity of the sorbent were studied. The sorbent exhibited extraordinary capture capacity with CO2 concentration ranging from 5% to 80%. The optimal PEI loading was determined to be 65 wt.% with a CO2 sorption capacity of 4.82 mmol-CO2/g-sorbent in 15% CO2/N2 at 75 degrees C, owing to low mass-transfer resistance and a high utilization ratio of the amine compound (63%). Moisture had a promoting effect on the sorption separation of CO2. In addition, the developed sorbent could be regenerated easily at 100 degrees C, and it exhibited excellent regenerability and stability. These results indicate that this PEI-loaded mesoporous carbon sorbent should have a good potential for CO2 capture in the future. PMID:23586307

  20. Microwave-Assisted Synthesis of Co-Coordinated Hollow Mesoporous Carbon Cubes for Oxygen Reduction Reactions.

    PubMed

    Chen, Lisong; Cui, Xiangzhi; Wang, Min; Du, Yanyan; Zhang, Xiaohua; Wan, Gang; Zhang, Linlin; Cui, Fangming; Wei, Chenyang; Shi, Jianlin

    2015-07-14

    Transition-metal-/metal-oxide-loaded mesoporous carbon materials with hollow structures are thought to have great potential as catalysts, especially in the areas of sustainable chemistry and energy conversion. However, it is hard to load transition metals/metal oxides onto carbon materials while keeping the carbon materials unchanged through traditional after-treatment processes, thus making it difficult to determine the true roles of the transition metal/metal oxide and carbon in the reactions. Here, Co-coordinated hollow mesoporous carbon cubes (CoMHMCCs) were prepared by a microwave-assisted approach in the presence of ethylene glycol and hollow mesoporous carbon cubes (HMCCs). The synthesized CoMHMCCs inherited most advantages of the HMCCs, such as large surface area and pore volume, uniform pore size distribution, and hollow mesoporous structure, and the Co species was found to coordinate with the N atoms in the N-doped hollow mesoporous carbon cubes. The synthesized CoMHMCCs exhibited a much enhanced oxygen electroreduction reaction activity (∼50 mV deviation from Pt/C), a high selectivity (number of electrons transferred = 3.7-3.9), and excellent electrochemical stability (as low as 12 mV negative shift of half-wave potential after 5000 potential cycles) as a result of a synergetic catalytic effect. PMID:26075681

  1. A comparison of the photocatalytic activity between commercial and synthesized mesoporous and nanocrystalline titanium dioxide for 4-nitrophenol degradation: Effect of phase composition, particle size, and addition of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Moro, Piera; Stampachiacchiere, Serena; Donzello, Maria Pia; Fierro, Giuseppe; Moretti, Giuliano

    2015-12-01

    The photodegradation of 4-nitrophenol in aqueous solution was studied by using titania-based photocatalysts, in particular standard commercial titania samples (anatase and rutile, Hunstmann; P25 and Aeroxide VP P90, Evonik) and a mesoporous and nanocrystalline titania synthesized under hydrothermal conditions. A comparison between the commercial products and our preparations made evident a different particle size and phase composition. Moreover, in order to investigate a possible synergism between TiO2 and carbon nanotubes (CNTs), further two samples were purposely synthesized by adding to the reaction mixture used for the catalyst preparation a small amount of single-walled or multi-walled carbon nanotubes (SWCNTs and MWCNTs). Among the investigated solids, the nanocrystalline titania resulted to be the most active photocatalysts. The less active solids were rutile and mesoporous titania. The addition of a small amount of MWCNTs further increased the photoactivity of the nanocrystalline titania.

  2. Mesoporous Carbon-based Materials for Alternative Energy Applications

    NASA Astrophysics Data System (ADS)

    Cross, Kimberly Michelle

    Increasing concerns for the escalating issues activated by the effect of carbon dioxide emissions on the global climate from extensive use of fossil fuels and the limited amount of fossil resources has led to an in-depth search for alternative energy systems, primarily based on nuclear or renewable energy sources. Recent innovations in the production of more efficient devices for energy harvesting, storage, and conversion are based on the incorporation of nanostructured materials into electrochemical systems. The aforementioned nano-electrochemical energy systems hold particular promise for alternative energy transportation related technologies including fuel cells, hydrogen storage, and electrochemical supercapacitors. In each of these devices, nanostructured materials can be used to increase the surface area where the critical chemical reactions occur within the same volume and mass, thereby increasing the energy density, power density, electrical efficiency, and physical robustness of the system. Durable corrosion resistant carbon support materials for fuel cells have been designed by adding conductive low cost carbon materials with chemically robust ceramic materials. Since a strict control of the pore size is mandatory to optimize properties for improved performance, chemical activation agents have been utilized as porogens to tune surface areas, pore size distributions, and composition of carbon-based mesoporous materials. Through the use of evaporative self-assembly methods, both randomly disordered and surfactant-templated, ordered carbon-silica nanocomposites have been synthesized with controlled surface area, pore volume, and pore size ranging from 50-800 m2/g, 0.025-0.75 cm3/g, and 2-10 nm, respectively. Multi-walled carbon nanotubes (MWNTs) ranging from 0.05-1.0 wt. % were added to the aforementioned carbon-silica nanocomposites, which provided an additional increase in surface area and improved conductivity. Initially, a conductivity value of 0.0667 S/cm was measured for the composite without carbon nanotubes and the conductivity value improved by over an order of magnitude to 1 S/cm with the addition of 0.5 wt.% CNTs. Triggered by dispersion issues, the agglomeration of MWNTs during the drying process prevented each nanotube from being loaded over a maximum interfacial area. In order to improve the dispersion of carbon nanotubes within the carbon-silica network, electrospinning was explored as a method to improve the alignment of the carbon nanotubes. The electrospun fibers produced with the highest concentration of MWNTs at 1.0 wt.% produced the largest surface area and electrical conductivity values of 333.36 m2/g and 2.09 S/cm, respectively. Capacitance measurements were calculated to examine if improved conductivity results in higher capacitance values. The best capacitance performance was 148 F/g from a carbon-based mesoporous composite with 0.5 wt. % MWNTs in an aqueous electrolyte with a 2.0 mV/s scan rate. An 80% increase in capacitance occurs with the addition of 0.5 wt. % MWNTs. This is in the range of capacitance values produced by hierarchically ordered mesoporous-microporous carbons, reported at 180 F/g. Fibrous carbon tubes assembled from hydrofluoric acid etched perylenetetracarboxylic diimide bridged silsesquioxane (PDBS) were capable of hydrogen adsorption on the order of 1.3-2.5 wt. % at 77K. Lastly chemically activated phenol-formaldehyde resins produced microporous carbon with 1500 m3/g surface areas and pore sizes ranging from 0.3-0.5 nm, which has potential for asymmetric super-capacitor electrodes. Judicious control over the composition and pore structure of carbon-based nanocomposites can lead to improved performance of various alternative energy materials.

  3. Template method synthesis of mesoporous carbon spheres and its applications as supercapacitors

    PubMed Central

    2012-01-01

    Mesoporous carbon spheres (MCS) have been fabricated from structured mesoporous silica sphere using chemical vapor deposition (CVD) with ethylene as a carbon feedstock. The mesoporous carbon spheres have a high specific surface area of 666.8?m2/g and good electrochemical properties. The mechanism of formation mesoporous carbon spheres (carbon spheres) is investigated. The important thing is a surfactant hexadecyl trimethyl ammonium bromide (CTAB), which accelerates the process of carbon deposition. An additional advantage of this surfactant is an increase the yield of product. These mesoporous carbon spheres, which have good electrochemical properties is suitable for supercapacitors. PMID:22643113

  4. Mesoporous Carbon Membranes for Selective Gas Separations

    SciTech Connect

    2009-04-01

    This factsheet describes a study whose focus is on translating a novel class of material developed at Oak Ridge National Laboratory—selfassembled mesoporous carbon—into robust, efficient membrane systems for selective industrial gas separations.

  5. Mesoporous carbon derived from vitamin B12: a high-performance bifunctional catalyst for imine formation.

    PubMed

    Chen, Bo; Shang, Sensen; Wang, Lianyue; Zhang, Yi; Gao, Shuang

    2016-01-11

    Mesoporous carbon derived from natural vitamin B12 is applied for the first time in organic synthesis and exhibits exceptionally high dual activity for imine formation via the cross-coupling of alcohols with amines and the self-coupling of primary amines using molecular oxygen or air as the terminal oxidant. PMID:26529323

  6. Mesoporous nitrogen-doped carbon derived from carp with high electrocatalytic performance for oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Wang, Rongfang; Song, Huihui; Li, Hao; Wang, Hui; Mao, Xuefeng; Ji, Shan

    2015-03-01

    In this work, a low-cost and nitrogen-containing carbon material with mesopores and high surface area is synthesized by carbonizing carp with SiO2 nanoparticles as template. It is found that pyridinic-N dominates the N species on the surface of obtained carbon material, which can act as active sites for oxygen reduction reaction (ORR). The BET surface area of obtained carbon material is 401.7 m2 g-1 and the pore size is ca. 11.1 nm. Due to its high pyridinic-N content and mesoporous architecture, the ORR activity of obtained carbon material in alkaline media is comparable to that of commercial Pt/C catalyst. In addition, it shows a higher methanol tolerance than Pt/C catalyst, making it a potential alternative to Pt-based catalysts.

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

    SciTech Connect

    Dai, Sheng; Fulvio, Pasquale F; Mayes, Richard T; Wang, Xiqing; Mahurin, Shannon Mark; Bauer, Christopher; Presser, Volker; Mcdonough, John; Gogotsi, Yury

    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 carbon 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.

  8. Incorporation of platinum nanoparticles in ordered mesoporous carbon.

    PubMed

    Wikander, Kjell; Hungria, Ana B; Midgley, Paul A; Palmqvist, Anders E C; Holmberg, Krister; Thomas, John M

    2007-01-01

    Platinum nanoparticles were incorporated within the pore system of ordered mesoporous carbon (OMC) by impregnating the carbon with a water-in-oil (w/o) microemulsion containing dissolved platinum salt followed by reduction of the platinum ions in situ inside the carbon pore system. The procedure provides preparation of metallic nanoparticles from hydrophilic precursors inside the hydrophobic carbon support structure with simultaneous control of the maximum metal particle size. Electron tomography was used to verify the presence of platinum nanoparticles inside the carbon material. PMID:17069827

  9. From polymeric "plasticine" to shape-controlled mesoporous carbon.

    PubMed

    Qian, Xu-Fang; Wang, Zheng; Wan, Ying

    2009-07-15

    A soft-phase intercalating process to synthesize mesostructured plasticine by using amphiphilic triblock copolymer F127 as a structure-directing agent, reverse triblock copolymer 25R4 as an intercalating soft matter, and soluble phenolic resin as a carbon source is demonstrated. The "plasticine" has interlayer organic-organic hybrid structure, which is emplastic, sticky, and able to be easily shaped at will. After template removal at 350 degrees C and further carbonization at 600 degrees C, highly ordered mesoporous polymers and carbons can be successively obtained with the maintenance of the original shape. The self-supported, shape-controlled, ordered mesoporous carbon products possess high surface areas (495-777 m(2)/g), large pore volumes (0.32-0.47 cm(3)/g), uniform pore sizes (2.5-4.3 nm) in the nanoscale and hollow tremella-like morphology in the micronscale which may facilitate mass transportation. PMID:19406429

  10. Soft-Template-Synthesized Mesoporous Carbon for Oral Drug Delivery

    SciTech Connect

    Saha, Dipendu; Warren, Kaitlyn E; Naskar, Amit K

    2014-01-01

    Template-synthesized mesoporous carbons were successfully used in in vitro investigations of controlled delivery of three model drugs, captopril, furosemide, and ranitidine hydrochloride. Captopril and furosemide exhibited desorption kinetics over 30 40 h, and ranitidine HCl had a complete release time of 5 10 h. As evident from the slow release kinetics, we contend that our mesoporous carbon is an improved drug-delivery medium compared to state-of-the-art porous silica-based substrates. The mesoporous carbons, synthesized from phloroglucinol and lignin, a synthetic and a sustainable precursor, respectively, exhibit BET surface area of 200 400 m2 g-1 and pore volume of 0.2 0.6 cm3 g-1. The phloroglucinol-based carbon has narrower pore widths and higher pore volume than the lignin-derived counterpart and maintains a longer release time. Numerical modeling of the release kinetics data reveals that the diffusivities of all the drugs from lignin-based carbon media are of equivalent magnitude (10-22 to 10-24 m2 s-1). However, a tailored reduction of pore width in the sorbent reduces the diffusivity of smaller drug molecules (captopril) by an order of magnitude. Thus, engineered pore morphology in our synthesized carbon sorbent, along with its potential to tailor the chemistry of its interaction with sorbet, can be exploited for optimal delivery system of a preferred drug within its therapeutic level and below the level of toxicity.

  11. Dealloying of mesoporous PtCu alloy film for the synthesis of mesoporous Pt films with high electrocatalytic activity.

    PubMed

    Li, Cuiling; Malgras, Victor; Aldalbahi, Ali; Yamauchi, Yusuke

    2015-02-01

    Mesoporous Pt film with highly electrocatalytic activity is successfully synthesized by dealloying of mesoporous PtCu alloy film prepared through electrochemical micelle assembly. The resulting mesoporous electrode exhibits high current density and superior stability toward the methanol oxidation reaction. PMID:25523238

  12. A 3D mesoporous polysulfone-carbon nanotube anode for enhanced bioelectricity output in microbial fuel cells.

    PubMed

    Nguyen, Tien-Hoa; Yu, Yang-Yang; Wang, Xin; Wang, Jing-Yuan; Song, Hao

    2013-11-25

    A facile fabrication method was developed to construct a three-dimensional (3D) mesoporous anode by coating single-walled carbon nanotubes (SWCNTs) on a mesoporous polysulfone matrix (MPPS) for microbial fuel cells (MFCs). Owing to highly active surface areas and efficient extracellular electron transfer between Shewanella cells and the anode, the MFC achieved an electricity output of 1410 mW m(-2), being one of the highest among the reported Shewanella-based MFCs. PMID:24108240

  13. Ordered mesoporous carbon-titania composites and their enhanced photocatalytic properties.

    PubMed

    Wickramaratne, Nilantha P; Jaroniec, Mietek

    2015-07-01

    A series of ordered mesoporous titania-carbon composites was synthesized by self-assembly of carbon and titania precursors in the presence of Pluronic F127 block copolymer as a template under acidic conditions. Resorcinol and formaldehyde were used as carbon precursors and titanium isopropoxide was employed as titania precursor. Pluronic F127 [poly(ethylene oxide) - poly(propylene oxide) - poly(ethylene oxide) triblock copolymer] was employed as a soft template. The controlled polymerization of phenolic resin precursors and condensation of titania precursor in hydrophilic domains of the block copolymer template followed by carbonization resulted in ordered mesoporous titania-carbon composites. These composites possessed uniform ordered cylindrical mesopores (7-8 nm) created by thermal decomposition of the soft template, crystalline titania particles (anatase phase, 7-8 nm) embedded in the carbon matrix, and high percentage of titania (up to 48%). N2 adsorption analysis showed that the aforementioned composites exhibited large surface area (close to reaching 600 m(2)/g) and enhanced photocatalytic activity toward photodegradation of rhodomine B due to the presence of titania nanoparticles uniformly dispersed in the carbon mesostructure. PMID:25648111

  14. One-Pot synthesis of phosphorylated mesoporous carbon heterogeneous catalysts with tailored surface acidity

    SciTech Connect

    Fulvio, Pasquale F; Mahurin, Shannon Mark; Mayes, Richard T; Bauer, Christopher; Wang, Xiqing; Veith, Gabriel M; Dai, Sheng

    2012-01-01

    Soft-templated phosphorylated mesoporous carbons with homogeneous distributions of phosphate groups were prepared by a 'one-pot' synthesis method using mixtures of phosphoric acid with hydrochloric, or nitric acids in the presence of Pluronic F127 triblock copolymer. Adjusting the various ratios of phosphoric acid used in these mixtures resulted in carbons with distinct adsorption, structural and surface acidity properties. The pore size distributions (PSDs) from nitrogen adsorption at -196 C showed that mesoporous carbons exhibit specific surface areas as high as 551 m{sup 2}/g and mesopores as large as 13 nm. Both structural ordering of the mesopores and the final phosphate contents were strongly dependent on the ratios of H{sub 3}PO{sub 4} in the synthesis gels, as shown by transmission electron microscopy (TEM), X-ray photoelectron (XPS) and energy dispersive X-ray spectroscopy (EDS). The number of surface acid sites determined from temperature programmed desorption of ammonia (NH{sub 3}-TPD) were in the range of 0.3-1.5 mmol/g while the active surface areas are estimated to comprise 5-54% of the total surface areas. Finally, the conversion temperatures for the isopropanol dehydration were lowered by as much as 100 C by transitioning from the least acidic to the most acidic catalysts surface.

  15. Graphene-Supported Mesoporous Carbons Prepared with Thermally Removable Templates as Efficient Catalysts for Oxygen Electroreduction.

    PubMed

    Niu, Wenhan; Li, Ligui; Liu, Ji; Wang, Nan; Li, Wei; Tang, Zhenghua; Zhou, Weijia; Chen, Shaowei

    2016-04-01

    Graphene-supported mesoporous carbons with rich nitrogen self-doped active sites (N-MC/rGO) are prepared by direct pyrolysis of a graphene-oxide-supported polymer composite embedded with massive, evenly distributed amorphous FeOOH that serve as efficient thermally removable templates. The resulting N-MC/rGO catalysts exhibit high surface areas and apparent electrocatalytic activity for oxygen reduction reaction in alkaline media. Among the series, the sample prepared at 800 °C displays the best performance with a more positive onset potential, higher limiting currents, much higher stability, and stronger poison resistance than commercial Pt/C. This is ascribed to the synergetic functions of the highly conductive graphene support and the mesoporous N-doped carbons that effectively impede the restacking of the graphene sheets and enhance the exposure of the rich nitrogen self-doped active sites. PMID:26895489

  16. Noncovalently functionalized graphitic mesoporous carbon as a stable support of Pt nanoparticles for oxygen reduction

    SciTech Connect

    Shao, Yuyan; Zhang, Sheng; Kou, Rong; Wang, Xiqing; Wang, Chong M.; Dai, Sheng; Viswanathan, Vilayanur V.; Liu, Jun; Wang, Yong; Lin, Yuehe

    2010-01-01

    We report the facile synthesis of an extremely durable electrocatalyst for oxygen reduction with highly graphitized mesoporous carbon (GMPC) as support (Pt/GMPC). GMPC is prepared through graphitizing the self-assembled soft-template mesoporous carbon (MPC) under high temperature. Most of the mesoporous structures and the specific surface area of MPC are retained even after 2800 °C heat-treatment, and the graphitization degree is greatly improved. GMPC is then noncovalently functionalized with poly(diallyldimethylammonium chloride) (PDDA) and then coated with Pt nanoparticles with ethylene glycol reduction method. Pt nanoparticles of ~3.0 nm in diameter are uniformly dispersed on GMPC. Pt/GMPC exhibits a higher activity towards oxygen reduction reaction (ORR) than Pt nanoparticles supported on Vulcan XC-72 carbon (Pt/XC-72). The durability of Pt/GMPC is improved by a factor of ~2 compared with Pt/XC-72. The enhanced activity and durability of Pt/GMPC are attributed to the graphitic structure of GMPC which makes GMPC more resistant to corrosion and the interaction between Pt nanoparticles and GMPC stronger. GMPC is promising as catalyst support. This provides a facile, eco-friendly promising strategy, avoiding the usually used chemical functionalization of carbon support with oxidizing strong acid, to synthesize electrocatalysts with high durability and activity for polymer electrolyte membrane fuel cells. This strategy can be widely applied in synthesizing metal nanoparticles on hydrophobic support materials.

  17. Paramagnetic muon states in mesoporous carbon materials

    NASA Astrophysics Data System (ADS)

    Macrae, R. M.; Upchurch, C.; Rose, D. K.; Miyake, Y.; Koda, A.; Lord, J. S.; Shuttleworth, P. S.

    2014-12-01

    We present results of longitudinal field repolarisation measurements carried out at J-PARC and ISIS on the "green" functional carbon materials Starbon 300 and Starbon 800, synthesized using starch as a template and subjected to pyrolysis treatments at different temperatures (300°C and 800°C respectively); pyrolysis at low temperature may be expected to yield a material retaining more of the "hydrophilic" properties of the original starch material in its chemically active voids, while high temperature pyrolysis may be expected to lead to "hydrophobic" voids and a more graphitic material. The hydrophilic material shows a larger repolarising fraction than the hydrophobic material, with a hyperfine constant on the order of 200-300 MHz. This is likely to be a superposition of the repolarisation of multiple radicals. Several candidate and model species are investigated through accompanying density functional theory calculations.

  18. Template-Engaged In Situ Synthesis of Carbon-Doped Monoclinic Mesoporous BiVO4: Photocatalytic Treatment of Rhodamine B

    NASA Astrophysics Data System (ADS)

    Yao, Mingming; Gan, Lihua; Liu, Mingxian; Tripathi, Pranav K.; Liu, Yafei; Hu, Zhonghua

    2015-06-01

    In this paper, carbon-doped monoclinic scheelite mesoporous bismuth vanadate was synthesized through template-engaged in situ method. The bismuth nitrate pentahydrate and ammonia metavanadate were used as bismuth and vanadium precursors, respectively, glucose as carbon source, and mesoporous SiO2 aerogel as a hard template. Carbon-doped monoclinic mesoporous BiVO4 were obtained by heat treatment of BiVO4/glucose/template to carbonize glucose and form monoclinic crystal, followed by etching with NaOH solution to remove the SiO2 template. The samples were characterized by x-ray diffraction, N2 adsorption and desorption, UV-visible spectroscopy, Energy dispersive spectrometry, Raman spectroscopy, and Transmission electron microscopy. It was found that the sample with a carbon content of 0.5 wt.% possesses a specific surface area of 10.2 m2/g and has mesoporous structure with the most probable pore size of 13.9 nm. The band gap of carbon-doped monoclinic mesoporous BiVO4 was estimated to be 2.33 eV, indicating the superior photocatalytic activity under visible light. The photocatalytic efficiency of carbon-doped monoclinic mesoporous BiVO4 for the degradation of Rhodamine B under visible light (λ > 400 nm) in 120 min reaches 98.7%, Besides, the carbon-doped monoclinic mesoporous BiVO4 photocatalyst still showed high stability: 85% for Rhodamine B degradation after ten recycles.

  19. Impregnation of Fenofibrate on mesoporous silica using supercritical carbon dioxide.

    PubMed

    Bouledjouidja, Abir; Masmoudi, Yasmine; Van Speybroeck, Michiel; Schueller, Laurent; Badens, Elisabeth

    2016-02-29

    Low oral bioavailability can be circumvented by the formulation of the poorly water soluble drug in ordered mesoporous silica (OMS-L-7). Fenofibrate is an orally administered, poorly water-soluble active pharmaceutical ingredient (API), used clinically to lower lipid levels. Fenofibrate was loaded into silica using two methods: incipient wetness and supercritical impregnation. This study investigates the impact of loading and the impact of varying supercritical carbon dioxide (scCO2) processing conditions. The objective is to enhance Fenofibrate loading into silica while reducing degree of the drug crystallinity, so as to increase the drug's dissolution rate and its bioavailability. The comparison of both impregnation processes was made in terms of impregnation yields and duration as well as physical characterization of the drug. While incipient wetness method led to a Fenofibrate loading up to 300mgdrug/gsilica in 48h of impregnation, the supercritical impregnation method yielded loading up to 485mgdrug/gsilica in 120min of impregnation duration, at 16MPa and 308K, with a low degree of crystallinity (about 1%) comparable to the crystallinity observed via the solvent method. In addition to the enhancement of impregnation efficiency, the supercritical route provides a solvent-free alternative for impregnation. PMID:26732521

  20. Synthesis of white light emitting mesoporous carbon-silica nanocomposite

    NASA Astrophysics Data System (ADS)

    Sato, Koji; Ishikawa, Yukari; Matsumura, Akihiro; Ishii, Yosuke; Kawasaki, Shinji

    2011-05-01

    White light emitting mesoporous carbon-silica (MPCS) was synthesized by serially adding triblock copolymer (Pluronic, F127), ethanol (EtOH), tetraethoxysilane (TEOS), hydrochloric acid aqueous (HCl) and phenol-formaldehyde resin (resol) followed by the heat treatments of carbonization and oxidation. The PL intensity of MPCS showed a tendency to be strong with increasing of HCl concentration in >= 0.2 M. The pore size of MPCS that emits white light was 8 ~ 9 nm and the specific surface area was 320 ~ 418 m2 / g.

  1. Microporosity development in phenolic resin-based mesoporous carbons for enhancing CO2 adsorption at ambient conditions

    NASA Astrophysics Data System (ADS)

    Choma, Jerzy; Jedynak, Katarzyna; Fahrenholz, Weronika; Ludwinowicz, Jowita; Jaroniec, Mietek

    2014-01-01

    Soft-templating method was used to prepare mesoporous carbons. The synthesis in the presence of hydrochloric and citric acids involved resorcinol and formaldehyde as carbon precursors and triblock copolymer Pluronic F127 as a template. The as-synthesized samples underwent carbonization in flowing nitrogen at various temperatures; namely 600 °C, 700 °C and 800 °C. Two routes were used to develop microporosity in the mesoporous carbons studied. The first one involved introduction of tetraethyl orthosilicate to the reaction system. After silica dissolution with NaOH, an increase in microporosity was observed. The second method, chemical activation with KOH at 700 °C, was explored as an alternative approach to create microporosity. It is noteworthy that the TEOS addition not only led to the development of microporosity but also to some improvement of mesoporosity. The post-synthesis KOH activation resulted in more significant increase in the microporosity as compared to the samples obtained by TEOS-assisted synthesis. The mesopore volume was somewhat lower for activated carbons as compared to that in mesoporous carbons. Both methods resulted in micro-mesoporous carbons with good adsorption properties; for instance, in the case of carbons prepared in the presence of TEOS, the best sample exhibited BET surface area of 1463 m2/g and the total pore volume of 1.31 cm3/g. For the KOH activated carbons the best adsorption parameters were as follows: the specific surface area = 1906 m2/g, and the total pore volume = 0.98 cm3/g. Both procedures used for microporosity development afforded carbons with good adsorption properties that can be useful for applications such as CO2 adsorption, air and water purification.

  2. Noncovalently functionalized graphitic mesoporous carbon as a stable support of Pt nanoparticles for oxygen reduction

    SciTech Connect

    Wang, Xiqing; Dai, Sheng; Engelhard, Mark H; Wang, Congmin; Liu, Jun; YANG, ZHENGUO; Lin, Yuehe; Shao, Yuyan

    2010-01-01

    We report a durable electrocatalyst support, highly graphitized mesoporous carbon (GMPC), for oxygen reduction in polymer electrolyte membrane (PEM) fuel cells. GMPC is prepared through graphitizing the self-assembled soft-template mesoporous carbon (MPC) under high temperature. Heat-treatment at 2800 C greatly improves the degree of graphitization while most of the mesoporous structures and the specific surface area of MPC are retained. GMPC is then noncovalently functionalized with poly(diallyldimethylammonium chloride) (PDDA) and loaded with Pt nanoparticles by reducing Pt precursor (H{sub 2}PtCl{sub 6}) in ethylene glycol. Pt nanoparticles of {approx}3.0 nm in diameter are uniformly dispersed on GMPC. Compared to Pt supported on Vulcan XC-72 carbon black (Pt/XC-72), Pt/GMPC exhibits a higher mass activity towards oxygen reduction reaction (ORR) and the mass activity retention (in percentage) is improved by a factor of {approx}2 after 44 h accelerated degradation test under the potential step (1.4-0.85 V) electrochemical stressing condition which focuses on support corrosion. The enhanced activity and durability of Pt/GMPC are attributed to the graphitic structure of GMPC which is more resistant to corrosion. These findings demonstrate that GMPC is a promising oxygen reduction electrocatalyst support for PEM fuel cells. The approach reported in this work provides a facile, eco-friendly promising strategy for synthesizing stable metal nanoparticles on hydrophobic support materials.

  3. White light emitting Mesoporous Carbon-Silica Nanocomposite

    NASA Astrophysics Data System (ADS)

    Matsumura, Akihiro; Ishii, Yosuke; Sato, Koji; Ishikawa, Yukari; Kawasaki, Shinji

    2011-05-01

    Visible photoluminescence (PL) from oxidized mesoporous carbon-silica nanocomposite (MPCS) prepared by the triconstituent co-assembly method is reported. White PL from MPCS was observed by naked eye at room temperature. Oxidation effects on carbon-silica bonding states and transmittance were investigated. PL intensity decreased with decreasing of carbon dangling bond density by oxidation at above 500 °C. The transmittance of MPCS at excitation and emission wavelengths increased with increasing of oxidation temperature. It is concluded that PL intensity is determined by the balance between PL related carbon density and transmittance. We proposed an additional wet oxidation that can increase PL intensity by the increase of transmittance under suppressing carbon desorption.

  4. Facile preparation of mesoporous carbon-silica-coated graphene for the selective enrichment of endogenous peptides.

    PubMed

    Zhang, Quanqing; Zhang, Qinghe; Xiong, Zhichao; Wan, Hao; Chen, Xiaoting; Li, Hongmei; Zou, Hanfa

    2016-01-01

    A sandwich-like composite composed of ordered mesoporous carbon-silica shell-coated graphene (denoted as graphene@mSiO2-C) was prepared by an in-situ carbonation strategy. A mesoporous silica shell was synthesized by a sol-gel method, and cetyltrimethyl ammonium bromide inside the mesopores were in-situ carbonized as a carbon source to obtain a carbon-silica shell. The resulting mesoporous carbon-silica material with a sandwich structure possesses a high surface area (600m(2)g(-1)), large pore volume (0.587cm(3)g(-1)), highly ordered mesoporous pore (3nm), and high carbon content (30%). This material shows not only high hydrophobicity of graphene and mesoporous carbon but also a hydrophilic silica framework that ensures excellent dispersibility in aqueous solution. The material can capture many more peptides from bovine serum albumin tryptic digests than mesoporous silica shell-coated graphene, demonstrating great enrichment efficiency for peptides. Furthermore, the prepared composite was applied to the enrichment of low-abundance endogenous peptides in human serum. Based on Matrix-Assisted Laser Desorption/ Ionization Time of Flight Mass Spectrometry identification, the graphene@mSiO2-C could efficiently size-exclude proteins and enriches the low-abundant peptides on the graphene and mesoporous carbon. And based on the LC-MS/MS results, 892 endogenous peptides were obtained by graphene@mSiO2-C, hinting at its great potential in peptides analysis. PMID:26695263

  5. Direct Electrochemistry and Electrocatalysis of Hemoglobin at Mesoporous Carbon Modified Electrode

    PubMed Central

    Pei, Supeng; Qu, Song; Zhang, Yongming

    2010-01-01

    The novel highly ordered mesoporous carbon (known as FDU-15), prepared by the organic-organic self-assembly method was been used for first time for the immobilization of hemoglobin (Hb) and its bioelectrochemical properties were studied. The resulting Hb/FDU-15 film provided a favorable microenvironment for Hb to perform direct electron transfers at the electrode. The immobilized Hb also displayed its good electrocatalytic activity for the reduction of hydrogen peroxide. The results demonstrate that mesoporous carbon FDU-15 can improve the Hb loading with retention of its bioactivity and greatly promote the direct electron transfer, which can be attributed to its high specific surface area, uniform ordered porous structure, suitable pore size and biocompatibility. Our present study may provide an alternative way for the construction of nanostructure biofunctional surfaces and pave the way for its application to biosensors. PMID:22205867

  6. Self-Templated Synthesis of Mesoporous Carbon from Carbon Tetrachloride Precursor for Supercapacitor Electrodes.

    PubMed

    Tang, Duihai; Hu, Shi; Dai, Fang; Yi, Ran; Gordin, Mikhail L; Chen, Shuru; Song, Jiangxuan; Wang, Donghai

    2016-03-23

    A high-surface-area mesoporous carbon material has been synthesized using a self-templating approach via reduction of carbon tetrachloride by sodium potassium alloy. The advantage is the reduction-generated salt templates can be easily removed with just water. The produced mesoporous carbon has a high surface area and a narrow pore size distribution. When used as a supercapacitor electrode, this material exhibits a high specific capacitance (259 F g(-1)) and excellent cycling performance (>92% capacitance retention for 6000 cycles). PMID:26913815

  7. Effect of multi-walled carbon nanotubes and conducting polymer on capacitance of mesoporous carbon electrode.

    PubMed

    Wang, Anmiao; Cheng, Yingwen; Zhang, Hongbo; Hou, Ye; Wang, Yanqin; Liu, Jie

    2014-09-01

    Porous carbon is the most widely used electrode materials in energy storage devices. It is generally accepted that in such electrodes, mesoporosity is more desired in supercapacitor than microporosity for the ions tranportation. However, the relatively poor conductivity of porous carbon often leads to low capacitance. To improve the capacity of mesoporous carbon based electrode, we designed a composite film composed of mesoporous carbon, multiwalled carbon nanotubes (MWNTs) and conducting polymer, Poly-3,4-ethylenedioxythiophene/poly(styrenesulfonate) (PEDOT-PSS), and hoped that each component in the composed film could contribute synergetically to improve electrochemical properties. The electrochemical performance of the film was evaluated by cyclic voltammetry and constant current charge/discharge method. With the assistance of MWNTs and conducting polymer, the specific capacitance of the mesoporous carbon based electrode was amplified six times. The electrode also presented excellent charge/discharge rate and good cycling stability, retaining about 94% of its initial capacitance after 1000 cycles. The results demonstrated that mesoporous carbon is more effectively utilized with assistance of MWNTs and conducting polymer in the electrode. Such method is very promising for the future applications of the porous carbon in electrode materials for high performance electrochemical supercapacitors. PMID:25924364

  8. A simple method to ordered mesoporous carbons containing nickel nanoparticles

    SciTech Connect

    Dai, Sheng; Wang, Xiqing

    2009-01-01

    A series of ordered mesoporous carbons containing magnetic Ni nanoparticles (Ni-OMCs) with a variety of Ni loadings was made by a simple one-pot synthetic procedure through carbonization of phenolic resin-Pluronic block copolymer composites containing various amount of nickel nitrate. Such composite materials were characterized by N{sub 2} sorption, XRD, and STEM. Ni-OMCs exhibited high BET surface area, uniform pore size, and large pore volume without obvious pore blockage with a Ni loading as high as 15 wt%. Ni nanoparticles were crystalline with a face-center-cubic phase and observed mainly in the carbon matrix and on the outer surface as well. The average particle size of Ni nanoparticles was dependent on the preparation (carbonization) temperature and Ni loading; the higher the temperature was used and the more the Ni was incorporated, the larger the Ni nanoparticles were observed. One of the applications of Ni-OMCs was demonstrated as magnetically separable adsorbents.

  9. Bio-mass derived mesoporous carbon as superior electrode in all vanadium redox flow battery with multicouple reactions

    NASA Astrophysics Data System (ADS)

    Ulaganathan, Mani; Jain, Akshay; Aravindan, Vanchiappan; Jayaraman, Sundaramurthy; Ling, Wong Chui; Lim, Tuti Mariana; Srinivasan, Madapusi P.; Yan, Qingyu; Madhavi, Srinivasan

    2015-01-01

    We first report the multi-couple reaction in all vanadium redox flow batteries (VRFB) while using bio-mass (coconut shell) derived mesoporous carbon as electrode. The presence of V3+/V4+ redox couple certainly supplies the additional electrons for the electrochemical reaction and subsequently provides improved electrochemical performance of VRFB system. The efficient electro-catalytic activity of such coconut shell derived high surface area mesoporous carbon is believed for the improved cell performance. Extensive power and electrochemical studies are performed for VRFB application point of view and described in detail.

  10. Carbothermal synthesis of ordered mesoporous carbon-supported nano zero-valent iron with enhanced stability and activity for hexavalent chromium reduction.

    PubMed

    Dai, Ying; Hu, Yuchen; Jiang, Baojiang; Zou, Jinlong; Tian, Guohui; Fu, Honggang

    2016-05-15

    Composites of nano zero-valent iron (nZVI) and ordered mesoporous carbon (OMC) are prepared by using simultaneous carbothermal reduction methods. The reactivity and stability of nZVI are expected to be enhanced by embedding it in the ordered pore channels. The structure characteristics of nZVI/OMC and the removal pathway for hexavalent chromium (Cr(VI)) by nZVI/OMC are investigated. Results show that nZVI/OMC with a surface area of 715.16m(2)g(-1) is obtained at 900°C. nZVI with particle sizes of 20-30nm is uniformly embedded in the OMC skeleton. The stability of nZVI is enhanced by surrounding it with a broad carbon layer and a little γ-Fe is derived from the passivation of α-Fe. Detection of ferric state (Fe 2p3/2, around 711.2eV) species confirms that part of the nZVI on the outer surface is inevitably oxidized by O2, even when unused. The removal efficiency of Cr(VI) (50mgL(-1)) by nZVI/OMC is near 99% within 10min through reduction (dominant mechanism) and adsorption. nZVI/OMC has the advantage in removal efficiency and reusability in comparison to nZVI/C, OMC and nZVI. This study suggests that nZVI/OMC has the potential for remediation of heavy metal pollution in water. PMID:25898797

  11. ESTERIFICATION OF OLEIC ACID IN SUPERCRITICAL CARBON DIOXIDE CATALYZED BY FUNCTIONALIZED MESOPOROUS SILICA AND AN IMMOBILIZED LIPASE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organosulfonic acid-functionalized mesoporous silicas were tested for catalytic performance in the esterification of oleic acid with methanol in flowing supercritical carbon dioxide. The energy of activation of the sulfonic acid catalysts was found to be about 42 kJ/mol and was shown to be independ...

  12. Synthesis of core-shell graphitic carbon@silica nanospheres with dual-ordered mesopores for cancer-targeted photothermochemotherapy.

    PubMed

    Wang, Yi; Wang, Kaiyuan; Zhang, Ren; Liu, Xingang; Yan, Xueying; Wang, Jianxin; Wagner, Ernst; Huang, Rongqin

    2014-08-26

    Tumor site-directed multifunctional therapeutic platforms such as photothermochemotherapy that respond to tumor-focused physical and biological stimuli are highly demanded for effective cancer therapy. Herein, targeting peptide-conjugated core–shell graphitic carbon@silica nanospheres with dual-ordered mesopores (MMPS) were successfully fabricated and developed as antitumoral doxorubicin (DOX) delivery system (MMPSD) for synergistic targeted photothermal chemotherapy of breast cancer. The hydrophilic mesoporous silica shell guarantees good water dispersity of MMPSD. The hydrophobic graphitic mesoporous carbon core provides excellent hydrophobic drug loading, immediate contact between the drug and photothermal hotspots, and high NIR photothermal conversion efficiency. SP13 peptide facilitates MMPSD for targeted and enhanced delivery of DOX within HER2-positive SK-BR-3 breast cancer cells, while PEGylation ensures biocompatibility. Thus, the MMPSD system exhibited efficient drug loading capacity, high targeting ability, sensitive NIR/pH-responsive DOX release, sustained release, and excellent combined antitumor activity. PMID:25046179

  13. Phosphorylated mesoporous carbon as effective catalyst for the selective fructose dehydration to HMF

    SciTech Connect

    Villa, Alberto; Schiavoni, Marco; Fulvio, Pasquale F; Mahurin, Shannon Mark; Dai, Sheng; Mayes, Richard T; Veith, Gabriel M; Prati, Laura

    2013-01-01

    Phosphorylated mesoporous carbons (PMCs) have been synthesized using an already reported one pot methodology. These materials have been applied as acidic catalysts in the dehydration of fructose to hydroxymethylfurfural (HMF). PMCs showed better selectivity to HMF compared to sulfonated carbon catalyst (SC) despite lower activity. The concentration of P-O groups correlates to the activity/selectivity of the catalysts; the higher the P-O concentration the higher the activity. However, the higher the P-O content the lower the selectivity to HMF. Indeed a lower concentration of the P-O groups (and even the acidic groups) minimized the degradation of HMF to levulinic acid and the formation of by-products, such as humines. Stability tests showed that these systems deactivate due to the formation of humines, water insoluble by-products derived from the dehydration of fructose, blocking the active site of the catalyst. Increasing the amount of P-O groups, higher amount of humines are formed; therefore carbons containing lower amount of phosphorylated groups, such as P/N-0.25, are less prone to deactivation. Keywords: Phosphorylated mesoporous carbons; fructose dehydration; HMF

  14. Morphology-dependent Li storage performance of ordered mesoporous carbon as anode material.

    PubMed

    Kim, Min-Sik; Bhattacharjya, Dhrubajyoti; Fang, Baizeng; Yang, Dae-Soo; Bae, Tae-Sung; Yu, Jong-Sung

    2013-06-01

    Rod-shaped ordered mesoporous carbons (OMCs) with different lengths, prepared by replication method using the corresponding size-tunable SBA-15 silicas with the same rodlike morphology as templates, are explored as anode material for Li-ion battery. All of the as-synthesized OMCs exhibit much higher Li storage capacity and better cyclability along with comparable rate capability as compared with commercial graphite. Particularly, the OMC-3 with the shortest length demonstrates the highest reversible discharge capacity of 1012 mAh g(-1) at 100 mA g(-1) and better cyclability with 86.6% retention of initial capacity after 100 cycles. Although the Coulombic efficiencies of all the OMCs are relatively low at the beginning, they improve promptly and after 10 cycles reach the level comparable to commercial graphite. Based on their specific capacity, cycle efficiency, and rate capability, the OMC-3 outperforms considerably its carbon peers, OMC-1 and OMC-2 with longer length. This behavior is mainly attributed to higher specific surface area, which provides more active sites for Li adsorption and storage along with the larger mesopore volume and shorter mesopore channels, which facilitate fast Li ion diffusion and electrolyte transport. The enhancement in reversible Li storage performance with decrease in the channel length is also supported by low solid electrolyte interphase resistance, contact resistance, and Warburg impedance in electrochemical impedance spectroscopy. PMID:23688326

  15. Adsorption of Pb(II) on mesoporous activated carbons fabricated from water hyacinth using H3PO4 activation: Adsorption capacity, kinetic and isotherm studies

    NASA Astrophysics Data System (ADS)

    Huang, Yang; Li, Shunxing; Chen, Jianhua; Zhang, Xueliang; Chen, Yiping

    2014-02-01

    Activated carbons with high mesoporosity and abundant oxygen-containing functional groups were prepared from water hyacinth using H3PO4 activation (WHAC) to eliminate Pb(II) in water. Characterizations of the WHAC were performed using Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The BET analysis showed that WHAC possesses a high mesoporosity (93.9%) with a BET surface area of 423.6 m2/g. The presence of oxygen-containing functional groups including hydroxyl, carbonyl, carboxyl and phosphate groups renders the WHAC a favorable adsorbent for Pb(II) with the maximum monolayer capacity (qm) 118.8 mg/g. The adsorption behavior follows pseudo-first order kinetic and Langmuir isotherm. The desorption study demonstrated that the WHAC could be readily regenerated using 0.1 M HCl (pH = 1.0). The desorbed WHAC could be reused at least six times without significant adsorption capacity reduction. The adsorption process was spontaneous and endothermic with ΔG (-0.27, -1.13, -3.02, -3.62, -5.54, and -9.31 kJ/mol) and ΔH (38.72 kJ/mol). Under the optimized conditions, a small amount of the adsorbent (1.0 g/L) could remove as much as 90.1% of Pb(II) (50 mg/L) in 20 min at pH 6.0 and temperature of 298 K. Therefore, the WHAC has a great potential to be an economical and efficient adsorbent in the treatment of lead-contaminated water.

  16. Nitrogen-doped mesoporous carbon of extraordinary capacitance for electrochemical energy storage

    NASA Astrophysics Data System (ADS)

    Lin, Tianquan; Chen, I.-Wei; Liu, Fengxin; Yang, Chongyin; Bi, Hui; Xu, Fangfang; Huang, Fuqiang

    2015-12-01

    Carbon-based supercapacitors can provide high electrical power, but they do not have sufficient energy density to directly compete with batteries. We found that a nitrogen-doped ordered mesoporous few-layer carbon has a capacitance of 855 farads per gram in aqueous electrolytes and can be bipolarly charged or discharged at a fast, carbon-like speed. The improvement mostly stems from robust redox reactions at nitrogen-associated defects that transform inert graphene-like layered carbon into an electrochemically active substance without affecting its electric conductivity. These bipolar aqueous-electrolyte electrochemical cells offer power densities and lifetimes similar to those of carbon-based supercapacitors and can store a specific energy of 41 watt-hours per kilogram (19.5 watt-hours per liter).

  17. Nitrogen-doped mesoporous carbon of extraordinary capacitance for electrochemical energy storage.

    PubMed

    Lin, Tianquan; Chen, I-Wei; Liu, Fengxin; Yang, Chongyin; Bi, Hui; Xu, Fangfang; Huang, Fuqiang

    2015-12-18

    Carbon-based supercapacitors can provide high electrical power, but they do not have sufficient energy density to directly compete with batteries. We found that a nitrogen-doped ordered mesoporous few-layer carbon has a capacitance of 855 farads per gram in aqueous electrolytes and can be bipolarly charged or discharged at a fast, carbon-like speed. The improvement mostly stems from robust redox reactions at nitrogen-associated defects that transform inert graphene-like layered carbon into an electrochemically active substance without affecting its electric conductivity. These bipolar aqueous-electrolyte electrochemical cells offer power densities and lifetimes similar to those of carbon-based supercapacitors and can store a specific energy of 41 watt-hours per kilogram (19.5 watt-hours per liter). PMID:26680194

  18. Polydopamine-graphene oxide derived mesoporous carbon nanosheets for enhanced oxygen reduction

    NASA Astrophysics Data System (ADS)

    Qu, Konggang; Zheng, Yao; Dai, Sheng; Qiao, Shi Zhang

    2015-07-01

    Composite materials combining nitrogen-doped carbon (NC) with active species represent a paramount breakthrough as alternative catalysts to Pt for the oxygen reduction reaction (ORR) due to their competitive activity, low cost and excellent stability. In this paper, a simple strategy is presented to construct graphene oxide-polydopamine (GD) based carbon nanosheets. This approach does not need to modify graphene and use any catalyst for polymerization under ambient conditions, and the obtained carbon nanosheets possess adjustable thicknesses and uniform mesoporous structures without using any template. The thickness of GD hybrids and the carbonization temperature are found to play crucial roles in adjusting the microstructure of the resulting carbon nanosheets and, accordingly their ORR catalytic activity. The optimized carbon nanosheet generated by a GD hybrid of 5 nm thickness after 900 °C carbonization exhibits superior ORR activity with an onset potential of -0.07 V and a kinetic current density of 13.7 mA cm-2 at -0.6 V. The unique mesoporous structure, high surface areas, abundant defects and favorable nitrogen species are believed to significantly benefit the ORR catalytic process. Furthermore, it also shows remarkable durability and excellent methanol tolerance outperforming those of commercial Pt/C. In view of the physicochemical versatility and structural tunability of polydopamine (PDA) materials, our work would shed new light on the understanding and further development of PDA-based carbon materials for highly efficient electrocatalysts.Composite materials combining nitrogen-doped carbon (NC) with active species represent a paramount breakthrough as alternative catalysts to Pt for the oxygen reduction reaction (ORR) due to their competitive activity, low cost and excellent stability. In this paper, a simple strategy is presented to construct graphene oxide-polydopamine (GD) based carbon nanosheets. This approach does not need to modify graphene and use any catalyst for polymerization under ambient conditions, and the obtained carbon nanosheets possess adjustable thicknesses and uniform mesoporous structures without using any template. The thickness of GD hybrids and the carbonization temperature are found to play crucial roles in adjusting the microstructure of the resulting carbon nanosheets and, accordingly their ORR catalytic activity. The optimized carbon nanosheet generated by a GD hybrid of 5 nm thickness after 900 °C carbonization exhibits superior ORR activity with an onset potential of -0.07 V and a kinetic current density of 13.7 mA cm-2 at -0.6 V. The unique mesoporous structure, high surface areas, abundant defects and favorable nitrogen species are believed to significantly benefit the ORR catalytic process. Furthermore, it also shows remarkable durability and excellent methanol tolerance outperforming those of commercial Pt/C. In view of the physicochemical versatility and structural tunability of polydopamine (PDA) materials, our work would shed new light on the understanding and further development of PDA-based carbon materials for highly efficient electrocatalysts. Electronic supplementary information (ESI) available: Preparation of graphene oxide, nitrogen adsorption analysis results, FTIR spectra, TEM images and elemental mapping, TGA, XPS and supplementary electrochemical tests. See DOI: 10.1039/c5nr03089g

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

    SciTech Connect

    Fulvio, P. F.; Mayes, R.; Wang, X. Q.; Mahurin, S., M.; Bauer, J. C.; Presser, V.; McDonough, J.; Gogotsi, Y.; Dai, S.

    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 carbon 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.

  20. Hydrolysis of Cellulose by a Mesoporous Carbon-Fe2(SO4)3/γ-Fe2O3 Nanoparticle-Based Solid Acid Catalyst

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Daizo; Watanabe, Koki; Fukumi, Shinya

    2016-02-01

    Carbon-based solid acid catalysts have shown significant potential in a wide range of applications, and they have been successfully synthesized using simple processes. Magnetically separable mesoporous carbon composites also have enormous potential, especially in separation and adsorption technology. However, existing techniques have been unable to produce a magnetically separable mesoporous solid acid catalyst because no suitable precursors have been identified. Herein we describe a magnetically separable, mesoporous solid acid catalyst synthesized from a newly developed mesoporous carbon-γ-Fe2O3 nanoparticle composite. This material exhibits an equivalent acid density and catalytic activity in the hydrolysis of microcrystalline cellulose, to that of the cellulose-derived conventional catalyst. Since it is magnetically separable, this material can be readily recovered and reused, potentially reducing the environmental impact of industrial processes to which it is applied.

  1. Hydrolysis of Cellulose by a Mesoporous Carbon-Fe2(SO4)3/γ-Fe2O3 Nanoparticle-Based Solid Acid Catalyst

    PubMed Central

    Yamaguchi, Daizo; Watanabe, Koki; Fukumi, Shinya

    2016-01-01

    Carbon-based solid acid catalysts have shown significant potential in a wide range of applications, and they have been successfully synthesized using simple processes. Magnetically separable mesoporous carbon composites also have enormous potential, especially in separation and adsorption technology. However, existing techniques have been unable to produce a magnetically separable mesoporous solid acid catalyst because no suitable precursors have been identified. Herein we describe a magnetically separable, mesoporous solid acid catalyst synthesized from a newly developed mesoporous carbon-γ-Fe2O3 nanoparticle composite. This material exhibits an equivalent acid density and catalytic activity in the hydrolysis of microcrystalline cellulose, to that of the cellulose-derived conventional catalyst. Since it is magnetically separable, this material can be readily recovered and reused, potentially reducing the environmental impact of industrial processes to which it is applied. PMID:26856604

  2. High-performance carbon nanotube-implanted mesoporous carbon spheres for supercapacitors with low series resistance

    SciTech Connect

    Yi, Bin; Chen, Xiaohua; Guo, Kaimin; Xu, Longshan; Chen, Chuansheng; Yan, Haimei; Chen, Jianghua

    2011-11-15

    Research highlights: {yields} CNTs-implanted porous carbon spheres are prepared by using gelatin as soft template. {yields} Homogeneously distributed CNTs form a well-develop network in carbon spheres. {yields} CNTs act as a reinforcing backbone assisting the formation of pore structure. {yields} CNTs improve electrical conductivity and specific capacitance of supercapacitor. -- Abstract: Carbon nanotube-implanted mesoporous carbon spheres were prepared by an easy polymerization-induced colloid aggregation method using gelatin as a soft template. Scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption measurements reveal that the materials are mesoporous carbon spheres, with a diameter of {approx}0.5-1.0 {mu}m, a specific surface area of 284 m{sup 2}/g and average pore size of 3.9 nm. Using the carbon nanotube-implanted mesoporous carbon spheres as electrode material for supercapacitors in an aqueous electrolyte solution, a low equivalent series resistance of 0.83 {Omega} cm{sup 2} and a maximum specific capacitance of 189 F/g with a measured power density of 8.7 kW/kg at energy density of 6.6 Wh/kg are obtained.

  3. Ordered mesoporous carbon electrodes for Li-O2 batteries.

    PubMed

    Park, Jin-Bum; Lee, Jinwoo; Yoon, Chong Seung; Sun, Yang-Kook

    2013-12-26

    Ordered mesoporous carbon (OMC) with highly ordered pore channels was applied as an oxygen-side electrode for a Li-O2 battery. To evaluate the effect of the pore channel size on battery performance, we employed OMCs possessing two different pore sizes (6 and 17 nm). When cycled at a current density of 200 mA g(-1)carbon, the OMC electrodes reduced polarization in the oxygen evolution reaction by 0.1 V compared to those consisting of conventional super P carbon electrode. X-ray diffraction and transmission electron microscopy of the discharged oxygen electrodes provided evidence for the formation of amorphous Li2O2, a product of the oxygen reduction reaction, inside the OMC pores rather than on the electrode surface as in the case of the super P electrode. The OMC electrodes were also effective at high current densities (500 mA g(-1)carbon and 1000 mA g(-1)carbon). PMID:24236914

  4. 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. PMID:24757995

  5. Enhancing adsorption efficiency of dichloroacetic acid onto mesoporous carbons: Procedure optimization, mechanism and characterization.

    PubMed

    Ding, Ying; Zhu, Jianzhong; Ji, Dongliang; Cao, Yang; Ling, Xiaojia; Chen, Wei

    2015-08-15

    Highly ordered mesoporous carbon may be directly synthesized via supramolecular self-assembly with in situ evaporation-induced crystallization process by controlling thermal reaction temperatures and carbon mass loading. In the present study, the effects of thermal reaction temperatures on the structural characterization and adsorption capacity of mesoporous carbon have been investigated and analyzed with orthogonal test experiments. The results show the carbonization temperature (R=32.1) plays a more important role than the self-assembly temperature (R=8.5) and thermal polymerization temperature (R=10.1) in manipulating the pore texture structures. The optimization grouping temperature was 40-110-500 °C. The optimum mesoporous carbon sample had the highest BET specific surface area (474 m(2)/g), the largest pore volume (0.46 cm(3)/g), and with reasonable uniform pore size distribution. The adsorption evaluation also shows the adsorption capacity is strongly correlated with the pore structure of mesoporous carbon, the optimized mesoporous carbon sample displayed the largest adsorption capacity (350 mg/g) at an initial concentration of 20.0 mg/L of dichloroacetic acid. The study results indicate optimization of thermal reaction parameters is an effective approach for synthesis of ordered mesoporous carbons. PMID:25935284

  6. Synthesis of Ordered Mesoporous Phenanthrenequinone-Carbon via π-π Interaction-Dependent Vapor Pressure for Rechargeable Batteries

    PubMed Central

    Kwon, Mi-Sook; Choi, Aram; Park, Yuwon; Cheon, Jae Yeong; Kang, Hyojin; Jo, Yong Nam; Kim, Young-Jun; Hong, Sung You; Joo, Sang Hoon; Yang, Changduk; Lee, Kyu Tae

    2014-01-01

    The π-π interaction-dependent vapour pressure of phenanthrenequinone can be used to synthesize a phenanthrenequinone-confined ordered mesoporous carbon. Intimate contact between the insulating phenanthrenequinone and the conductive carbon framework improves the electrical conductivity. This enables a more complete redox reaction take place. The confinement of the phenanthrenequinone in the mesoporous carbon mitigates the diffusion of the dissolved phenanthrenequinone out of the mesoporous carbon, and improves cycling performance. PMID:25490893

  7. Hollow mesoporous carbon nitride nanosphere/three-dimensional graphene composite as high efficient electrocatalyst for oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Qin, Yong; Li, Juan; Yuan, Jie; Kong, Yong; Tao, Yongxin; Lin, Furong; Li, Shan

    2014-12-01

    Hollow mesoporous carbon nitride nanosphere (HMCN) is firstly prepared via an etching route using hollow mesoporous silica as a sacrificial template. The as-obtained HMCN is a uniform spherical particle with a diameter of ˜300 nm,and possesses a high specific surface area up to 439 m2 g-1. Hollow mesoporous carbon nitride nanosphere/three-dimensional (3D) graphene composite (HMCN-G) is subsequently fabricated via a hydrothermal treatment of HMCN with graphene oxide. As an electrocatalyst for oxygen reduction reaction (ORR), the HMCN-G shows significantly enhanced electrocatalytic activity compared to bulk graphitic carbon nitride (g-C3N4) and HMCN in terms of the electron-transfer number, current density and onset potential. Increased density of catalytically active sites and improved accessibility to electrolyte enabled by the hollow and mesoporous architecture of HMCN, and high conductivity induced from graphene are considered to contribute to the remarkable electrocatalytic performance of the HMCN-G. Furthermore, HMCN-G exhibits superior methanol tolerance to Pt/C catalyst, suggesting that it is a promising metal-free electrocatalyst for polymer electrolyte membrane fuel cell (PEMFC).

  8. Cu Nanoparticles Inlaid Mesoporous Carbon Aerogels as a High Performance Desulfurizer.

    PubMed

    Wu, Jiang; Yang, Siyuan; Liu, Qizhen; He, Ping; Tian, Huan; Ren, Jianxing; Guan, ZhenZhen; Hu, Tao; Ni, Bu; Zhang, Chong

    2016-05-17

    In the present study, to insert the Cu nanoparticles (NPs) into mesoporous carbon aerogels and first applied it to remove H2S efficiently. This desulfurizer was made based on the dimensional policy by inserting the Cu NPs on mesoporous carbon aerogels to overcome the sintering problem and improve the activity, which has potential performance at high-temperature catalysis. The obtained desulfurizer was employed for H2S removal at middle temperature conditions (optimal H2S adsorption at 550 °C). We explored the optimum doping amount of CuOx, optimum temperature conditions, and the influence of textural parameters of carbon aerogels. The desulfurizers were characterized by means of field-emission scanning electron microscopy (FESEM), N2-adsorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR), and Raman spectra techniques. The results confirmed that the presence of H2 was unfavorable for sulfidation and obviously shortened the breakthrough time. However, the existence of CO had little impact on the desulfurization and sulfur capacity. In a nutshell, this work could provide a new synthetic route to prepare Cu NPs deep into the lattice of carbon aerogels structure of desulfurizers and understand the desulfurization mechanism. PMID:27128500

  9. Synthesis, characterization and magnetic performance of Co-incorporated ordered mesoporous carbons

    SciTech Connect

    Liu, Zhi; Song, Yan; Yang, Yuan; Mi, Junhua; Deng, Liping

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer A facile one-pot aqueous self-assembly strategy for the synthesis Co-incorporated ordered mesoporous carbons (Co-OMCs). Black-Right-Pointing-Pointer Co-OMCs exhibit typical ferromagnetic characteristics. Black-Right-Pointing-Pointer Saturation magnetization strength can be easily adjusted by changing the content of cobalt. Black-Right-Pointing-Pointer Carbonization temperatures have significant effects on the structure and magnetic properties of Co-OMCs. -- Abstract: Co-incorporated ordered mesoporous carbon (Co-OMC) with magnetic frameworks has been synthesized via a one-pot self-assembly strategy. The effects of cobalt loading on carbon matrix, adsorption properties and magnetic properties of the resultant mesostructured cobalt/carbon composites were investigated by nitrogen sorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TG) and magnetometer measurements. The results show that the mesoporous composites with a high cobalt content (such as 18.0 wt%) possess an ordered and uniform mesoporous structure (5.3 nm), high surface areas (up to 687 m{sup 2}/g) and high pore volumes (up to 0.54 cm{sup 3}/g). Cobalt nanoparticles of size 4-9 nm are confined inside the mesopores or walls of the mesoporous carbon. These materials exhibit typical ferromagnetic characteristics. The saturation magnetization strength can be easily adjusted by changing the content of cobalt. The carbonization temperatures have significant effects on the structure and magnetic properties of Co-OMC also.

  10. IL-derived N, S co-doped ordered mesoporous carbon for high-performance oxygen reduction

    NASA Astrophysics Data System (ADS)

    Yang, Wenxiu; Yue, Xiaoyu; Liu, Xiangjian; Zhai, Junfeng; Jia, Jianbo

    2015-07-01

    A highly efficient N, S co-doped porous carbon ORR catalyst was simply designed in our report from ordered mesoporous carbon (OMC) and trace ionic liquids (ILs). The microstructure OMC was chosen as the template for improving the specific area, confining the ILs in the mesopores, and promoting the formation of the planar N and S doping. The resulting IL/OMC (IOMC) nanostructure exhibits comparable ORR activity and better stability than the commercial Pt/C catalyst in 0.10 M KOH solution, which makes it one of the best-performing metal-free carbon ORR catalysts. We deduced that the excellent ORR activity is attributed to the synergistic effect of N, S, and the ordered mesoporous structure. Interestingly, the ORR activity can be further boosted in both basic and acidic solutions after Fe doping into the IOMC nanostructures which clearly emphasizes that transition metal Fe is important for the construction of ORR active functional sites especially in acidic solution.A highly efficient N, S co-doped porous carbon ORR catalyst was simply designed in our report from ordered mesoporous carbon (OMC) and trace ionic liquids (ILs). The microstructure OMC was chosen as the template for improving the specific area, confining the ILs in the mesopores, and promoting the formation of the planar N and S doping. The resulting IL/OMC (IOMC) nanostructure exhibits comparable ORR activity and better stability than the commercial Pt/C catalyst in 0.10 M KOH solution, which makes it one of the best-performing metal-free carbon ORR catalysts. We deduced that the excellent ORR activity is attributed to the synergistic effect of N, S, and the ordered mesoporous structure. Interestingly, the ORR activity can be further boosted in both basic and acidic solutions after Fe doping into the IOMC nanostructures which clearly emphasizes that transition metal Fe is important for the construction of ORR active functional sites especially in acidic solution. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02497h

  11. Supported mesoporous carbon ultrafiltration membrane and process for making the same

    DOEpatents

    Strano, Michael; Foley, Henry C.; Agarwal, Hans

    2004-04-13

    A novel supported mesoporous carbon ultrafiltration membrane and process for producing the same. The membranes comprise a mesoporous carbon layer that exists both within and external to the porous support. A liquid polymer precursor composition comprising both carbonizing and noncarbonizing templating polymers is deposited on the porous metal support. The coated support is then heated in an inert-gas atmosphere to pyrolyze the polymeric precursor and form a mesoporous carbon layer on and within the support. The pore-size of the membranes is dependent on the molecular weight of the noncarbonizing templating polymer precursor. The mesoporous carbon layer is stable and can withstand high temperatures and exposure to organic chemicals. Additionally, the porous metal support provides excellent strength properties. The composite structure of the membrane provides novel structural properties and allows for increased operating pressures allowing for greater membrane flow rates. The invention also relates to the use of the novel ultrafiltration membrane to separate macromolecules from solution. An example is shown separating bovine serum albumin from water. The membrane functions by separating and by selective adsorption. Because of the membrane's porous metal support, it is well suited to industrial applications. The unique properties of the supported mesoporous carbon membrane also allow the membrane to be used in transient pressure or temperature swing separations processes. Such processes were not previously possible with existing mesoporous membranes. The present invention, however, possesses the requisite physical properties to perform such novel ultrafiltration processes.

  12. Enhanced capacitive deionization of graphene/mesoporous carbon composites

    NASA Astrophysics Data System (ADS)

    Zhang, Dengsong; Wen, Xiaoru; Shi, Liyi; Yan, Tingting; Zhang, Jianping

    2012-08-01

    Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are well retained and the composites display improved specific surface area and pore size distribution, as well as pore volume. Well dispersed GE nanosheets are deduced to be beneficial for enhanced electrical conductivity. The electrochemical performance of electrodes in an NaCl aqueous solution was characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements. The composite electrodes perform better on the capacitance values, conductive behaviour, rate performance and cyclic stability. The desalination capacity of the electrodes was evaluated by a batch mode electrosorptive experiment and the amount of adsorbed ions can reach 731 μg g-1 for the GE/MC composite electrode with a GE content of 5 wt%, which is much higher than that of MC alone (590 μg g-1). The enhanced CDI performance of the composite electrodes can be attributed to the better conductive behaviour and higher specific surface area.Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are well retained and the composites display improved specific surface area and pore size distribution, as well as pore volume. Well dispersed GE nanosheets are deduced to be beneficial for enhanced electrical conductivity. The electrochemical performance of electrodes in an NaCl aqueous solution was characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements. The composite electrodes perform better on the capacitance values, conductive behaviour, rate performance and cyclic stability. The desalination capacity of the electrodes was evaluated by a batch mode electrosorptive experiment and the amount of adsorbed ions can reach 731 μg g-1 for the GE/MC composite electrode with a GE content of 5 wt%, which is much higher than that of MC alone (590 μg g-1). The enhanced CDI performance of the composite electrodes can be attributed to the better conductive behaviour and higher specific surface area. Electronic supplementary information (ESI) available: Experimental details. XRD patterns, TEM image and nitrogen adsorption-desorption isotherms of the samples. Cyclic voltammograms and galvanostatic charge-discharge curves of the GE/MC electrodes. See DOI: 10.1039/c2nr31154b

  13. Soybean-derived mesoporous carbon as an effective catalyst support for electrooxidation of methanol

    NASA Astrophysics Data System (ADS)

    Zhou, Tianbao; Wang, Hui; Ji, Shan; Linkov, Vladimir; Wang, Rongfang

    2014-02-01

    In this work, a low cost and nitrogen-containing carbon (CS) with mesoporous structure and high surface area is synthesized by carbonizing soybean. It is found that the prepared CS has excellent textural properties such as high specific surface areas and large pore diameters. TEM images show that the Pt nano-sized dendrites are well formed on the surface of CS. Compared to Pt supported on Vulcan carbon XC-72, electrochemical results show that Pt supported on CS possesses a higher electrocatalytic activity and better durability in methanol oxidation reaction, which are mainly attributed to the support effect of CS resulting in the unique morphology of Pt particles and high content of Pt(0). These results indicate that CS has great potential as a high-performance catalyst support for fuel cell electrocatalysis.

  14. Transition metal ion capture using functional mesoporous carbon made with 1,10-phenanthroline

    SciTech Connect

    Chouyyok, Wilaiwan; Yantasee, Wassana; Shin, Yongsoon; Grudzien, Rafal M.; Fryxell, Glen E.

    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 a 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.

  15. A mesoporous carbon-supported Pt nanocatalyst for the conversion of lignocellulose to sugar alcohols.

    PubMed

    Park, Dae Sung; Yun, Danim; Kim, Tae Yong; Baek, Jayeon; Yun, Yang Sik; Yi, Jongheop

    2013-12-01

    The conversion of lignocellulose is a crucial topic in the renewable and sustainable chemical industry. However, cellulose from lignocellulose is not soluble in polar solvents, and is, therefore, difficult to convert into value-added chemicals. A strategy to overcome this drawback is the use of mesoporous carbon, which enhances the affinity between the cellulose and the catalyst through its abundant functional groups and large uniform pores. Herein, we report on the preparation of a Pt catalyst supported on a type of 3D mesoporous carbon inspired by Echinometra mathae (Pt/CNE) to enhance the interaction between the catalyst and a nonsoluble reactant. In the hydrolytic hydrogenation of cellulose, the abundant oxygen groups of CNE facilitated the access of cellulose to the surface of the catalyst, and the open pore structure permits cello-oligomers to effectively diffuse to the active sites inside the pore. The highly dispersed Pt performed dual roles: hydrolysis by in situ generating protons from H2 or water as well as effective hydrogenation. The use of the Pt/CNE catalyst resulted in an approximately 80 % yield of hexitol, the best performance reported to date. In direct conversion of hardwood powder, the Pt/CNE shows good performance in the production of sugar alcohols (23 % yield). We expect that the open-structured 3D carbon will be widely applied to the conversion of various lignocellulosic materials. PMID:24227502

  16. 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. PMID:25213723

  17. Synthesis and microwave absorbing properties of FeNi alloy incorporated ordered mesoporous carbon-silica nanocomposite

    NASA Astrophysics Data System (ADS)

    Li, Guoxian; Guo, Yunxia; Sun, Xin; Wang, Tao; Zhou, Jianhua; He, Jianping

    2012-11-01

    Ordered mesoporous carbon-silica/FeNi nanocomposite were prepared by a sol-gel method and following sintering process. The electromagnetic parameters were measured in the 0.5-18 GHz range. Compared with ordered mesoporous carbon-silica composite, the permittivity of ordered mesoporous carbon-silica/FeNi nanocomposite decreases, while the permeability almost remains unchanged. The optimal reflection loss of ordered mesoporous carbon-silica/FeNi nanocomposite can reach -45.6 dB at 11.1 GHz for a layer thickness of 3.0 mm. The enhanced microwave absorption of the mesoporous carbon-silica/FeNi nanocomposite is due to better balance between the complex permittivity and permeability, geometrical effect, as well as multiple reflections by the ordered mesoporous structure.

  18. Influence of spatial configurations on electromagnetic interference shielding of ordered mesoporous carbon/ordered mesoporous silica/silica composites

    PubMed Central

    Wang, Jiacheng; Zhou, Hu; Zhuang, Jiandong; Liu, Qian

    2013-01-01

    Ordered mesoporous carbons (OMCs), obtained by nanocasting using ordered mesoporous silicas (OMSs) as hard templates, exhibit unique arrangements of ordered regular nanopore/nanowire mesostructures. Here, we used nanocasting combined with hot-pressing to prepare 10 wt% OMC/OMS/SiO2 ternary composites possessing various carbon mesostructure configurations of different dimensionalities (1D isolated CS41 carbon nanowires, 2D hexagonal CMK-3 carbon, and 3D cubic CMK-1 carbon). The electric/dielectric properties and electromagnetic interference (EMI) shielding efficiency (SE) of the composites were influenced by spatial configurations of carbon networks. The complex permittivity and the EMI SE of the composites in the X-band frequency range decreased for the carbon mesostructures in the following order: CMK-3-filled > CMK-1-filled > CS41-filled. Our study provides technical directions for designing and preparing high-performance EMI shielding materials. Our OMC-based silica composites can be used for EMI shielding, especially in high-temperature or corrosive environments, owing to the high stability of the OMC/OMS fillers and the SiO2 matrix. Related shielding mechanisms are also discussed. PMID:24248277

  19. Influence of spatial configurations on electromagnetic interference shielding of ordered mesoporous carbon/ordered mesoporous silica/silica composites

    NASA Astrophysics Data System (ADS)

    Wang, Jiacheng; Zhou, Hu; Zhuang, Jiandong; Liu, Qian

    2013-11-01

    Ordered mesoporous carbons (OMCs), obtained by nanocasting using ordered mesoporous silicas (OMSs) as hard templates, exhibit unique arrangements of ordered regular nanopore/nanowire mesostructures. Here, we used nanocasting combined with hot-pressing to prepare 10 wt% OMC/OMS/SiO2 ternary composites possessing various carbon mesostructure configurations of different dimensionalities (1D isolated CS41 carbon nanowires, 2D hexagonal CMK-3 carbon, and 3D cubic CMK-1 carbon). The electric/dielectric properties and electromagnetic interference (EMI) shielding efficiency (SE) of the composites were influenced by spatial configurations of carbon networks. The complex permittivity and the EMI SE of the composites in the X-band frequency range decreased for the carbon mesostructures in the following order: CMK-3-filled > CMK-1-filled > CS41-filled. Our study provides technical directions for designing and preparing high-performance EMI shielding materials. Our OMC-based silica composites can be used for EMI shielding, especially in high-temperature or corrosive environments, owing to the high stability of the OMC/OMS fillers and the SiO2 matrix. Related shielding mechanisms are also discussed.

  20. Influence of spatial configurations on electromagnetic interference shielding of ordered mesoporous carbon/ordered mesoporous silica/silica composites.

    PubMed

    Wang, Jiacheng; Zhou, Hu; Zhuang, Jiandong; Liu, Qian

    2013-01-01

    Ordered mesoporous carbons (OMCs), obtained by nanocasting using ordered mesoporous silicas (OMSs) as hard templates, exhibit unique arrangements of ordered regular nanopore/nanowire mesostructures. Here, we used nanocasting combined with hot-pressing to prepare 10 wt% OMC/OMS/SiO2 ternary composites possessing various carbon mesostructure configurations of different dimensionalities (1D isolated CS41 carbon nanowires, 2D hexagonal CMK-3 carbon, and 3D cubic CMK-1 carbon). The electric/dielectric properties and electromagnetic interference (EMI) shielding efficiency (SE) of the composites were influenced by spatial configurations of carbon networks. The complex permittivity and the EMI SE of the composites in the X-band frequency range decreased for the carbon mesostructures in the following order: CMK-3-filled > CMK-1-filled > CS41-filled. Our study provides technical directions for designing and preparing high-performance EMI shielding materials. Our OMC-based silica composites can be used for EMI shielding, especially in high-temperature or corrosive environments, owing to the high stability of the OMC/OMS fillers and the SiO2 matrix. Related shielding mechanisms are also discussed. PMID:24248277

  1. Nitrogen-doped dual mesoporous carbon for the selective oxidation of ethylbenzene.

    PubMed

    Chen, Aibing; Yu, Yifeng; Wang, Rujie; Yu, Yunhong; Zang, Wenwei; Tang, Pei; Ma, Ding

    2015-09-21

    A nanocasting method to fabricate nitrogen-doped dual mesoporous carbon is proposed by the carbonization of nitrile functional ionic liquid (FIL) grafted SBA-15 for the first time. These carbon materials have high nitrogen content (12.8%), large specific surface areas (763 m(2) g(-1)) and uniform rod morphologies, which are derived from FILs grafted on the surface of SBA-15. Furthermore, by adjusting the impregnation amount of ionic liquids on SBA-15, pore structures of these carbon materials can be adjusted from single to dual mesopores. The developed dual mesoporous carbon materials exhibit good catalytic performance in the selective oxidation of ethylbenzene, ascribed to the promoting effects of nitrogen-doping, high surface area and dual mesostructure. It may be concluded that the dual mesostructure has an advantage over a single mesostructure to obtain a fast mass transport rate, resulting in higher acetophenone yield. PMID:26274862

  2. Platinum supported on mesoporous carbon as cathode catalyst for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Bruno, Mariano M.; Viva, Federico A.; Petruccelli, M. Agustina; Corti, Horacio R.

    2015-03-01

    Platinum nanoparticles supported on mesoporous carbon were obtained by an impregnation and reduction method with NaBH4 as the reducing agent. The high specific surface area mesoporous carbon was obtained by carbonization of a resorcinol-formaldehyde polymer with a cationic polyelectrolyte as a soft template. Surface characterization performed by transmission electron microscopy and powder X-ray diffraction showed a homogeneous distribution and high dispersion of the metal particles on the mesoporous support. The carbon-supported Pt catalyst was employed as cathode catalyst in a direct methanol fuel cell where a 30% increase in power density was obtained when compared to Pt supported on Vulcan carbon, under the same conditions.

  3. Catalytic Mesoporous Janus Nanomotors for Active Cargo Delivery

    PubMed Central

    2015-01-01

    We report on the synergy between catalytic propulsion and mesoporous silica nanoparticles (MSNPs) for the design of Janus nanomotors as active cargo delivery systems with sizes <100 nm (40, 65, and 90 nm). The Janus asymmetry of the nanomotors is given by electron beam (e-beam) deposition of a very thin platinum (2 nm) layer on MSNPs. The chemically powered Janus nanomotors present active diffusion at low H2O2 fuel concentration (i.e., <3 wt %). Their apparent diffusion coefficient is enhanced up to 100% compared to their Brownian motion. Due to their mesoporous architecture and small dimensions, they can load cargo molecules in large quantity and serve as active nanocarriers for directed cargo delivery on a chip. PMID:25844893

  4. Catalytic mesoporous Janus nanomotors for active cargo delivery.

    PubMed

    Ma, Xing; Hahn, Kersten; Sanchez, Samuel

    2015-04-22

    We report on the synergy between catalytic propulsion and mesoporous silica nanoparticles (MSNPs) for the design of Janus nanomotors as active cargo delivery systems with sizes <100 nm (40, 65, and 90 nm). The Janus asymmetry of the nanomotors is given by electron beam (e-beam) deposition of a very thin platinum (2 nm) layer on MSNPs. The chemically powered Janus nanomotors present active diffusion at low H2O2 fuel concentration (i.e., <3 wt %). Their apparent diffusion coefficient is enhanced up to 100% compared to their Brownian motion. Due to their mesoporous architecture and small dimensions, they can load cargo molecules in large quantity and serve as active nanocarriers for directed cargo delivery on a chip. PMID:25844893

  5. Thermal-stable carbon nanotube-supported metal nanocatalysts by mesoporous silica coating.

    PubMed

    Sun, Zhenyu; Zhang, Hongye; Zhao, Yanfei; Huang, Changliang; Tao, Ranting; Liu, Zhimin; Wu, Zhenduo

    2011-05-17

    A universal strategy was developed for the preparation of high-temperature-stable carbon nanotube (CNT) -supported metal nanocatalysts by encapsulation with a mesoporous silica coating. Specifically, we first showed the design of one novel catalyst, Pt(@)CNT/SiO(2), with a controllable mesoporous silica coating in the range 11-39 nm containing pores ≈3 nm in diameter. The hollow porous silica shell offers a physical barrier to separate Pt nanoparticles from contact with each other, and at the same time the access of reactant species to Pt was not much affected. As a result, the catalyst showed high thermal stability against metal particle agglomeration or sintering even after being subjected to harsh treatments up to 500 °C. In addition, degradation in catalytic activity was minimized for the hydrogenation of nitrobenzene over the catalyst treated at 300 °C for 2 h. The scheme was also extended to coat porous silica onto the surfaces of CuRu(@)CNT and the resultant catalyst thereby can be reusable at least four times without loss of activity for the hydrogenolysis of glycerol. These results suggest that the as-prepared nanostructured CNT-supported catalysts may find promising applications, especially in those processes requiring rigorous conditions. PMID:21480615

  6. Surface texture and physicochemical characterization of mesoporous carbon--wrapped Pd-Fe catalysts for low-temperature CO catalytic oxidation.

    PubMed

    Han, Weiliang; Zhang, Guodong; Zhao, Kun; Lu, Gongxuan; Tang, Zhicheng

    2015-11-21

    In this paper, mesoporous carbon (meso-C) with three-dimensional mesoporous channels was synthesized through a nanocasting route using three-dimensional mesoporous silica KIT-6 as the template. Mesoporous carbon wrapped Pd-Fe nanocomposite catalysts were synthesized by the co-precipitation method. The effects of the experimental conditions, such as pH value, Fe loading content and calcination temperature, on CO oxidation were studied in detail. The prepared Pd-Fe/meso-C catalysts showed excellent catalytic activity after optimizing the experimental conditions. The surface tetravalent Pd content, existing forms of Fe species, surface chemical adsorbed oxygen concentration, and pore channels of mesoporous carbon played vital roles in achieving the highest performance for the Pd-Fe/meso-C catalyst. The reaction pathway was conjectured according to the XPS analysis of the Pd-Fe/meso-C catalysts for CO oxidation, which maybe adhered to the Langmuir-Hinshelwood + redox mechanism. The effect of moisture on CO conversion was investigated, and the superior Pd-Fe/meso-C catalyst could maintain its activity beyond 12 h. This catalyst also showed excellent activity compared to the reported values in the existing literature. PMID:26456796

  7. Phosphorus-doped ordered mesoporous carbons with different lengths as efficient metal-free electrocatalysts for oxygen reduction reaction in alkaline media.

    PubMed

    Yang, Dae-Soo; Bhattacharjya, Dhrubajyoti; Inamdar, Shaukatali; Park, Jinsol; Yu, Jong-Sung

    2012-10-01

    Phosphorus-doped ordered mesoporous carbons (POMCs) with different lengths were synthesized using a metal-free nanocasting method of SBA-15 mesoporous silica with different sizes as template and triphenylphosphine and phenol as phosphorus and carbon sources, respectively. The resultant POMC with a small amount of P doping is demonstrated as a metal-free electrode with excellent electrocatalytic activity for oxygen reduction reaction (ORR), coupled with much enhanced stability and alcohol tolerance compared to those of platinum via four-electron pathway in alkaline medium. Interestingly, the POMC with short channel length is found to have superior electrochemical performances compared to those with longer sizes. PMID:22966761

  8. Hierarchical mesoporous/microporous carbon with graphitized frameworks for high-performance lithium-ion batteries

    SciTech Connect

    Lv, Yingying; Fang, Yin; Qian, Xufang; Tu, Bo; Wu, Zhangxiong; Asiri, Abdullah M.; Zhao, Dongyuan

    2014-11-01

    A hierarchical meso-/micro-porous graphitized carbon with uniform mesopores and ordered micropores, graphitized frameworks, and extra-high surface area of ∼2200 m{sup 2}/g, was successfully synthesized through a simple one-step chemical vapor deposition process. The commercial mesoporous zeolite Y was utilized as a meso-/ micro-porous template, and the small-molecule methane was employed as a carbon precursor. The as-prepared hierarchical meso-/micro-porous carbons have homogeneously distributed mesopores as a host for electrolyte, which facilitate Li{sup +} ions transport to the large-area micropores, resulting a high reversible lithium ion storage of 1000 mA h/g and a high columbic efficiency of 65% at the first cycle.

  9. Hyaluronic acid modified mesoporous carbon nanoparticles for targeted drug delivery to CD44-overexpressing cancer cells

    NASA Astrophysics Data System (ADS)

    Wan, Long; Jiao, Jian; Cui, Yu; Guo, Jingwen; Han, Ning; Di, Donghua; Chang, Di; Wang, Pu; Jiang, Tongying; Wang, Siling

    2016-04-01

    In this paper, hyaluronic acid (HA) functionalized uniform mesoporous carbon spheres (UMCS) were synthesized for targeted enzyme responsive drug delivery using a facile electrostatic attraction strategy. This HA modification ensured stable drug encapsulation in mesoporous carbon nanoparticles in an extracellular environment while increasing colloidal stability, biocompatibility, cell-targeting ability, and controlled cargo release. The cellular uptake experiments of fluorescently labeled mesoporous carbon nanoparticles, with or without HA functionalization, demonstrated that HA-UMCS are able to specifically target cancer cells overexpressing CD44 receptors. Moreover, the cargo loaded doxorubicin (DOX) and verapamil (VER) exhibited a dual pH and hyaluronidase-1 responsive release in the tumor microenvironment. In addition, VER/DOX/HA-UMCS exhibited a superior therapeutic effect on an in vivo HCT-116 tumor in BALB/c nude mice. In summary, it is expected that HA-UMCS will offer a new method for targeted co-delivery of drugs to tumors overexpressing CD44 receptors.

  10. Foamed mesoporous carbon/silicon composite nanofiber anode for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Yuxin; Wen, Xiufang; Chen, Juan; Wang, Shengnian

    2015-05-01

    A new porous composite nanofiber manufacturing route, combining electrospinning and foaming processes, was developed. In this process, aluminum acetylacetonate (AACA) was introduced as the foaming agent in nanofibers made of polyacrylonitrile (PAN)/silicon (Si) nanoparticles. PAN/Si composite nanofibers were first produced through an electrospinning process and mesopores were then generated by foaming nanofibers via AACA sublimation. After further carbonization, the obtained mesoporous carbon/silicon composite nanofiber mats were tested as the anode material for lithium ion batteries. Within this composite anode, mesopores provide needed buffering space to accommodate the large volume expansion and consequent stress induced inside silicon during lithiation. This effectively mitigates silicon pulverization issue and helps achieve higher reversible capacity and better capacity retention in later battery tests when compared with anodes made of nonporous composites nanofibers and carbon nanofibers alone.

  11. Nitrogen-Rich Mesoporous Carbon as Anode Material for High-Performance Sodium-Ion Batteries.

    PubMed

    Liu, Huan; Jia, Mengqiu; Sun, Ning; Cao, Bin; Chen, Renjie; Zhu, Qizhen; Wu, Feng; Qiao, Ning; Xu, Bin

    2015-12-16

    Nitrogen-rich carbon with interconnected mesoporous structure has been simply prepared via a nano-CaCO3 template method, using polyaniline as carbon and nitrogen precursors. The preparation process includes in situ polymerization of aniline in a nano-CaCO3 aqueous solution, carbonization of the composites and removal of the template with diluted hydrochloric acid. Nitrogen sorption shows the carbon-enriched mesopores with a specific surface area of 113 m(2) g(-1). The X-ray photoelectron spectroscopy (XPS) analysis indicates that the carbon has a high nitrogen content of 7.78 at. %, in the forms of pyridinic and pyrrolic, as well as graphitic nitrogen. The nitrogen-rich mesoporous carbon shows a high reversible capacity of 338 mAh g(-1) at a current density of 30 mA g(-1), and good rate performance as well as ultralong cycling durability (110.7 mAh g(-1) at a current density of 500 mA g(-1) over 800 cycles). The excellent sodium storage performance of the nitrogen-rich mesoporous carbon is attributed to its disordered structure with large interlayer distance, interconnected porosity, and the enriched nitrogen heteroatoms. PMID:26588502

  12. Soft-template-carbonization route to highly textured mesoporous carbon-TiO₂ inverse opals for efficient photocatalytic and photoelectrochemical applications.

    PubMed

    Quan, Li Na; Jang, Yoon Hee; Stoerzinger, Kelsey A; May, Kevin J; Jang, Yu Jin; Kochuveedu, Saji Thomas; Shao-Horn, Yang; Kim, Dong Ha

    2014-05-21

    Hierarchically organized mesoporous carbon-TiO2 inverse opal nanostructures were synthesized by complementary colloid and block copolymer (BCP) self-assembly, where the triblock copolymer P123 acts simultaneously as the template and the carbon source. Highly ordered mesoporous inverse opal nanostructures with a nano-textured surface morphology and multiple-length scale nanopores provide increased light-activated surface area and scattering effects, leading to enhanced photoabsorption efficiency and the transport of matter. UV-vis absorption, X-ray photoelectron spectroscopy and Mott-Schottky measurement studies show that incorporation of carbon moieties into TiO2via direct conversion of BCPs creates a new energy level above the valence band of TiO2, resulting in an effective decrease in the band gap. A significantly enhanced visible light photocatalytic activity was demonstrated for the mesoporous carbon-TiO2 inverse opals in terms of the degradation of p-nitrophenol (~79%) and photoelectrochemical water splitting (~0.087%). PMID:24695759

  13. "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. PMID:26418602

  14. PdCl2-loading mesoporous copper oxide as a novel and environmentally friendly catalyst for diethyl carbonate synthesis

    NASA Astrophysics Data System (ADS)

    Zhang, Pingbo; Zhou, Yan; Fan, Mingming; Jiang, Pingping

    2015-03-01

    PdCl2-loading mesoporous copper oxide (PdCl2/mCuO) catalysts were successfully synthesized via a hard template with copper carbonate basic (Cu2(OH)2CO3), cupric nitrate (Cu(NO3)2·3H2O) and copper citrate (Cu2C6H4O7·2.5H2O) as the copper(II) precursors, respectively. Their catalytic performances were investigated in the synthesis of diethyl carbonate (DEC) by oxidative carbonylation of ethanol with CO and O2. The catalysts were characterized by TGA, XRD, nitrogen adsorption-desorption analysis and SEM with the aim of establishing their composition, morphology and structure. It was observed that the catalysts all showed a good selectivity to diethyl carbonate. However, due to a better mesoporous structure such as a bigger surface area, more uniform particle size and less agglomeration, the PdCl2/mCuO-1 catalyst prepared with Cu2(OH)2CO3 precursor showed a better catalytic activity that the conversion of EtOH was about 4.8% and the STY of DEC was 97.1 mg g-1 h-1. This was because the highly developed mesoporous structure could generate a bigger surface area, which benefited the contact between reactants and active sites, improved the conversion of ethanol, and thus enhanced the catalytic performance. Furthermore, a synthetic procedure diagram about "wet impregnation" method of mesoporous CuO prepared with Cu2(OH)2CO3 precursor was given to illustrate these results intuitively.

  15. Synthesis of N-Doped Hollow-Structured Mesoporous Carbon Nanospheres for High-Performance Supercapacitors.

    PubMed

    Liu, Chao; Wang, Jing; Li, Jiansheng; Zeng, Mengli; Luo, Rui; Shen, Jinyou; Sun, Xiuyun; Han, Weiqing; Wang, Lianjun

    2016-03-23

    We have demonstrated a facile and controllable synthesis of monodispersed N-doped hollow mesoporous carbon nanospheres (N-HMCSs) and yolk-shell hollow mesoporous carbon nanospheres (N-YSHMCSs) by a modified "silica-assisted" route. The synthesis process can be carried out by using resorcinol-formaldehyde resin as a carbon precursor, melamine as a nitrogen source, hexadecyl trimethylammonium chloride as a template, and silicate oligomers as structure-supporter. The morphological (i.e., particle size, shell thickness, cavity size, and core diameter) and textural features of the carbon nanospheres are easily controlled by varying the amount of ammonium. The resultant carbon nanospheres possess high surface areas (up to 2464 m(2) g(-1)), large pore volumes (up to 2.36 cm(3) g(-1)), and uniform mesopore size (∼2.4 nm for N-HMCSs, ∼ 4.5 nm for N-YSHMCSs). Through combining the hollow mesoporous structure, high porosity, large surface area, and N heteroatomic functionality, the as-synthesized N-doped hollow-structured carbon nanospheres manifest excellent supercapacitor performance with high capacitance (up to 240 F/g), favorable capacitance retention (97.0% capacitive retention after 5000 cycles), and high energy density (up to 11.1 Wh kg(-1)). PMID:26942712

  16. Selenium sulfide@mesoporous carbon aerogel composite for rechargeable lithium batteries with good electrochemical performance

    NASA Astrophysics Data System (ADS)

    Zhang, Zhian; Jiang, Shaofeng; Lai, Yanqing; Li, Junming; Song, Junxiao; Li, Jie

    2015-06-01

    Selenium sulfide (SeS2) encapsulated into 3D interconnected mesoporous carbon aerogels (MCA) as a selenium sulfide/carbon composite material was prepared for lithium batteries. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observations show the mesoporous structures of the carbon aerogels and the homogeneous distribution of selenium sulfide in the composite. The electrochemical performances of the selenium sulfide@mesoporous carbon aerogel (SeS2@MCA) composite cathode was evaluated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. It is found that the SeS2@MCA cathode shows a better electrochemical performance than the pristine SeS2 cathode. The SeS2@MCA composite with selenium sulfide content of 49.3 wt.% displays an initial discharge capacity of 1150 mAh g-1 at 50 mA g-1 and a reversible discharge capacity of 601 mAh g-1 after 10 cycles at 500 mA g-1. The better electrochemical performance benefit from the high electron conductivity and 3D interconnected porous structures of the carbon aerogels, which contribute to dispersing SeS2 and trapping polysulfide and polyselenide intermediates within the skeleton structure of the mesoporous carbon aerogels.

  17. Hydrothermal synthesis of magnetic mesoporous carbon microspheres from carboxymethylcellulose and nickel acetate

    NASA Astrophysics Data System (ADS)

    Wu, Qiong; Li, Wei; Tan, Jia; Nan, Xi; Liu, Shouxin

    2015-03-01

    Paramagnetic mesoporous carbon spheres with diameters of 1-3 μm were synthesized through the hydrothermal carbonization of carboxymethylcellulose with nickel acetate, followed by high-temperature carbonization in a N2 atmosphere. Monodisperse Ni particles of average size of 2-5 nm were doped into the carbon matrix, and covered the entrances of pores. Ni particles existed as metallic nickel and nickel oxide with ordered lattice structures. The effect of Ni content on the specific surface area, mesopore percentage, and magnetic and adsorption properties were investigated. The highest vitamin B12 adsorption capacity of 103 mg/g was achieved for the sample prepared using 0.04 g of nickel acetate. The Freundlich and Langmuir isotherm models were used to determine the equilibrium uptakes of vitamin B12. Vitamin B12 was physically adsorbed as a monolayer on the carbon spheres. The carbon spheres were easily separated on account of their magnetism.

  18. Fabrication of ordered mesoporous carbon film supporting vanadium oxides for electrochemical supercapacitor

    NASA Astrophysics Data System (ADS)

    Zhao, Chunxia; Li, Junshen; Cao, Jinqiao; Chen, Wen

    2015-11-01

    Ordered mesoporous carbon film supporting vanadium oxide nanoparticles has been synthesized via ultrasound-assistant impregnation method with ordered mesoporous carbon C-FDU15 film as the host and V2O5 sol as the guest precursor. The hybrids exhibit type IV sorption isotherms with H2 hysteresis loop, indicating the well-retained characteristics of ordered mesoporous structure. The capacitance of the materials is enhanced with V2O5 loading. Particularly, the hybrids with 32.26 wt.% V2O5 loading yield an important capacitance of 128 F/g in 1 mol/L KNO3 electrolyte under a potential range from -0.6 V to 0.6 V. The improved specific capacitance of the hybrids is proposed to be the combination of the double-layer capacitance of ordered porous structure and the pseudocapacitance derived from V2O5.

  19. A novel low-temperature dendritic cyclotrimerization of 2,6-diacetyl pyridine leading to mesoporous carbon containing pyridine rings

    SciTech Connect

    Shin, Yongsoon; Wang, Chong M.; Engelhard, Mark H.; Fryxell, Glen E.

    2009-07-01

    A simple, direct synthesis of a mesoporous carbon containing pyridine rings is described. This synthesis utilizes the SiCl4 induced cyclotrimerization of 2,6-diacetylpyridine to make a dendritic polymer, built of alternating benzene and pyridine rings. The cyclotrimerization allows for a high degree of crosslinking to take place at low temperatures stabilizing the mesostructure and allowing the carbonization to be carried out at only 600°C, the lowest temperature reported to date for an N-doped mesoporous carbon. The functional mesoporous carbon so formed was found to have a surface area of 1275 m2/g, 35Å pores, and contain 6.8% N.

  20. Properties of a three-dimensionally ordered macro-mesoporous carbon-doped TiO2 composite catalyst

    NASA Astrophysics Data System (ADS)

    Sui, Wubin; Zheng, Jingtang; Pittman, Charles U.; Bensalah, Nasr; Wu, Mingbo; Zhao, Yucui

    2014-11-01

    This study aimed to develop an effective, environmentally benign composite catalyst composed of carbon materials and titanium dioxide (TiO2). Carbon-doped titanium dioxide (C-TiO2) was prepared by coating TiO2 onto macro-mesoporous carbon (MMC). The structure, morphology and surface chemistry states of the C-TiO2 were characterized by XRD, TEM, XPS, UV-vis and FTIR. The photocatalytic activity of C-TiO2 was evaluated based on the decomposition of an aqueous methyl orange solution in visible light. C-TiO2 significantly improved photocatalytic activity. A possible mechanism for the improvement of the photocatalytic activity of C-TiO2 in visible light was proposed. The results of the analysis suggested that MMC played key roles as the support, absorbent, location of photo-generated electron transfer, and carbon-doping source during methyl orange photodegradation.

  1. Preparation and CO2 adsorption properties of soft-templated mesoporous carbons derived from chestnut tannin precursors

    DOE PAGESBeta

    Nelson, Kimberly M.; Mahurin, Shannon Mark; Mayes, Richard T.; Teague, Craig M.; Binder, Andrew J.; Baggetto, Loic; Veith, Gabriel M.; Dai, Sheng; Williamson, Ben

    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 CO2 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 CO2 capture.« less

  2. Preparation and CO2 adsorption properties of soft-templated mesoporous carbons derived from chestnut tannin precursors

    SciTech Connect

    Nelson, Kimberly M.; Mahurin, Shannon Mark; Mayes, Richard T.; Teague, Craig M.; Binder, Andrew J.; Baggetto, Loic; Veith, Gabriel M.; Dai, Sheng; Williamson, Ben

    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 mesostructures 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 CO2 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 CO2 capture.

  3. Synthesis, characterization and catalytic activity of a novel mesoporous ZSM-5 zeolite

    SciTech Connect

    Ma, Yuanyuan; Hu, Jing; Jia, Lihua; Li, Zhifang; Kan, Qiubin; Wu, Shujie

    2013-05-15

    Highlights: ► Mesoporous ZSM-5 zeolites. ► The strong acidic intensity. ► High activity for the alkylation of phenol and tert-butyl alcohol. ► Remarkable hydrothermal stability. - Abstract: A novel mesoporous ZSM-5 zeolite was hydrothermally synthesized using glucose as a template. Characterizations by XRD, TEM and nitrogen isotherms indicated that ZSM-5 possessed worm-like mesoporous. {sup 27}Al-MAS-NMR and NH{sub 3}-TPD showed that the mesoporous ZSM-5 preserved tetrahedral coordination aluminum and stronger acidity than conventional mesoporous material. As-prepared mesoporous ZSM-5 was successfully used in alkylation reaction of phenol with tert-butanol and exhibited significantly high phenol conversion and 2,4-DTBP selectivity. In addition, the hydrothermal stability was also studied by boiling in water for 7 days and displayed good results.

  4. Ordered mesoporous carbon nanochannel reactors for high-performance Fischer-Tropsch synthesis.

    PubMed

    Ha, Kyoung-Su; Kwak, Geunjae; Jun, Ki-Won; Hwang, Jongkook; Lee, Jinwoo

    2013-06-01

    A hexagonally ordered mesoporous carbon, CMK-3, was utilized as a support for a Fischer-Tropsch catalyst. Each array of elongated pore structures with Co nanoparticles can be regarded as a nanochannel reactor. Due to the pore confinement and the hydrophobic nature of the support, this catalyst demonstrated excellent catalytic performance. PMID:23482917

  5. Effect of diffuse layer and pore shapes in mesoporous carbon supercapacitors

    SciTech Connect

    Huang, Jingsong; Sumpter, Bobby G; Meunier, Vincent; Qiao, Rui

    2010-01-01

    In the spirit of the theoretical evolution from the Helmholtz model to the Gouy Chapman Stern model for electric double-layer capacitors, we explored the effect of a diffuse layer on the capacitance of mesoporous carbon supercapacitors by solving the Poisson Boltzmann (PB) equation in mesopores of diameters from 2 to 20 nm. To evaluate the effect of pore shape, both slit and cylindrical pores were considered. We found that the diffuse layer does not affect the capacitance significantly. For slit pores, the area-normalized capacitance is nearly independent of pore size, which is not experimentally observed for template carbons. In comparison, for cylindrical pores, PB simulations produce a trend of slightly increasing area-normalized capacitance with pore size, similar to that depicted by the electric double-cylinder capacitor model proposed earlier. These results indicate that it is appropriate to approximate the pore shape of mesoporous carbons as being cylindrical and the electric double-cylinder capacitor model should be used for mesoporous carbons as a replacement of the traditional Helmholtz model.

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

    SciTech Connect

    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. 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.

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

    DOE PAGESBeta

    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

  8. Colloidal mesoporous silica nanoparticles enhance the biological activity of resveratrol.

    PubMed

    Summerlin, Natalie; Qu, Zhi; Pujara, Naisarg; Sheng, Yong; Jambhrunkar, Siddharth; McGuckin, Michael; Popat, Amirali

    2016-08-01

    The naturally occurring polyphenol resveratrol (RES) has attracted increasing attention in recent years due to its antioxidant, anti-inflammatory, and anticancer activity. However, resveratrol's promising potential as a nutraceutical is hindered by its poor aqueous solubility, which limits its biological activity. Here we show that encapsulating resveratrol in colloidal mesoporous silica nanoparticles (MCM-48-RES) enhances its saturated solubility by ∼95% and increases its in vitro release kinetics compared to pure resveratrol. MCM-48-RES showed high loading capacity (20% w/w) and excellent encapsulation efficiency (100%). When tested against HT-29 and LS147T colon cancer cell lines, MCM-48-RES-mediated in vitro cell death was higher than that of pure resveratrol, mediated via the PARP and cIAP1 pathways. Finally, MCM-48-RES treatment also inhibited lipopolysaccharide-induced NF-κB activation in RAW264.7 cells, demonstrating improved anti-inflammatory activity. More broadly, our observations demonstrate the potential of colloidal mesoporous silica nanoparticles as next generation delivery carriers for hydrophobic nutraceuticals. PMID:27060664

  9. Novel mesoporous P-doped graphitic carbon nitride nanosheets coupled with ZnIn2S4 nanosheets as efficient visible light driven heterostructures with remarkably enhanced photo-reduction activity.

    PubMed

    Chen, Wei; Liu, Tian-Yu; Huang, Ting; Liu, Xiao-Heng; Yang, Xu-Jie

    2016-02-14

    In this report, we rationally designed and fabricated P-C3N4/ZnIn2S4 nanocomposites by in situ immobilizing ZnIn2S4 nanosheets onto the surface of mesoporous P-doped graphite carbon nitrogen (P-C3N4) nanosheets in a mixed solvothermal environment; their application to the photoreduction of 4-nitroaniline was used to estimate the photocatalytic performance. Different to the template route, here the mesoporous P-C3N4 nanosheets were prepared with a template-free strategy. The as-fabricated P-C3N4/ZnIn2S4 nanocomposites were systematically characterized by analyzing the phase structure, chemical components, electronic and optical properties and separation of charge carrier pairs. More importantly, these P-C3N4/ZnIn2S4 heterostructures have been proven to be highly efficient visible light responsive photocatalysts for photo-reduction, and meanwhile exhibit excellent photo-stability during recycling runs. The sufficient evidence reveals that the significantly improved photocatalytic performance is mainly attributed to the more efficient charge carrier separation based on the construction of a close heterogeneous interface. This work may provide new insights into the utilization of P-C3N4/ZnIn2S4 nanocomposites as visible light driven photocatalysts for comprehensive organic transformations in the field of fine chemical engineering. PMID:26815611

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

    SciTech Connect

    Li Siheng; Qi Li; Lu Lehui; Wang Hongyu

    2013-01-15

    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{sub 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.

  11. 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. PMID:26241936

  12. Mesoporous carbon -Cr2O3 composite as an anode material for lithium ion batteries

    SciTech Connect

    Guo, Bingkun; Chi, Miaofang; Sun, Xiao-Guang; Dai, Sheng

    2012-01-01

    Mesoporous carbon-Cr2O3 (M-C-Cr2O3) composite was prepared by co-assembly of in-situ formed phenolic resin, chromium precursor, and Pluronic block copolymer under acidic conditions, followed by carbonization at 750oC under Argon. The TEM results confirmed that the Cr2O3 nanoparticles, ranging from 10 to 20 nm, were well dispersed in the matrix of mesoporous carbon. The composite exhibited an initial reversible capacity of 710 mAh g-1 and good cycling stability, which is mainly due to the synergic effects of carbons within the composites, i.e. confining the crystal growth of Cr2O3 during the high temperature treatment step and buffering the volume change of Cr2O3 during the cycling step. This composite material is a promising anode material for lithium ion batteries.

  13. Zeolite materials prepared using silicate waste from template synthesis of ordered mesoporous carbon.

    PubMed

    Kim, Yun Kyung; Rajesh, Kizhakke Palleeri; Yu, Jong-Sung

    2013-09-15

    Significant amount of silica waste is generated in the preparation of porous carbon materials using template synthesis. Industrial production of such porous carbon not only creates waste chemicals, but also poses significant environmental concerns and high waste treatment cost. Recycling is proposed as the best solution for tackling such chemical wastes. In this study, etched silica waste released from template synthesis of mesoporous carbon is recycled to produce precious functional microporous zeolite materials. The solid silica template is etched out with NaOH solution to produce silica-free mesoporous carbon. The collected silica waste is recycled to generate zeolites such as LTA and MFI type silica materials. The formation of zeolites is confirmed by FT-IR, XRD, (29)Si NMR, (27)Al NMR, and SEM. This straight forward green chemistry route not only recycles the waste chemicals, but also decreases environmental pollution for better improvement of our living. PMID:23792927

  14. Synthesis of pore-variable mesoporous CdS and evaluation of its photocatalytic activity in degrading methylene blue

    SciTech Connect

    Zhang, Wei-Min; Jiang, Yao-Quan; Cao, Xiao-Yan; Chen, Meng; Ge, Dong-Lai; Sun, Zhong-Xi

    2013-10-15

    Graphical abstract: - Highlights: • Self-templated synthesis of tubular CdS. • Cadmium complexes of aliphatic acids sustain the network of mesoporous structures. • Aliphatic acids affect the phase composition and particle size. • Pore size and volume vary with aliphatic acids having different hydrocarbonyl. - Abstract: In this study, mesoporous CdS polycrystallites have been synthesized using aliphatic acids of hexanoic acid, octanoic acid, and oleic acid as coordinating and capping agents, respectively. The fibrous Cd–fatty acid salts act as a template to form the tubular CdS. The organic species are found to be necessary for maintaining the network of mesoporous CdS. The characterization results indicate that the shorter carbon chain length in aliphatic acids favors the wurtzite phase and particle size growth the specific surface area, pore diameter and pore volume show a monotonic raise with increasing carbon chain. The photocatalytic activities of mesoporous CdS tubes exhibit much higher efficiency than those of nanosized CdS powders in decolorizing methylene blue under simulated visible light.

  15. Electrochemical properties of boron-doped ordered mesoporous carbon as electrocatalyst and Pt catalyst support.

    PubMed

    Nsabimana, Anaclet; Bo, Xiangjie; Zhang, Yufan; Li, Mian; Han, Ce; Guo, Liping

    2014-08-15

    The electrochemical properties of boron-doped ordered mesoporous carbon (BOMC) as an electrode material and Pt catalyst support were investigated. The BOMC was synthesized and its structure was examined by transmission electron microscopy (TEM), scanning electron microscopy, nitrogen adsorption-desorption, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). More defective sites were introduced into OMC by the doping of boron. Six electroactive compounds were employed to investigate their electrochemical responses on BOMC and OMC modified glassy carbon electrodes. The BOMC, with more defective sites, exhibited high activity toward the electroactive compounds. The property of BOMC of supporting platinum nanoparticle catalyst was examined. Pt nanoparticles were loaded onto BOMC and OMC, and this was confirmed by TEM, XPS and thermogravimetric analysis. Pt nanoparticles with an average diameter of 2.62 nm were deposited on BOMC. The doping of boron into OMC facilitates the dispersion of Pt nanoparticles. Pt nanoparticles supported on BOMC (Pt-BOMC) and Pt nanoparticles supported on OMC (Pt-OMC) were electrochemically characterized. The electrocatalytic activity of Pt-BOMC toward methanol oxidation reaction was compared with that of Pt-OMC and commercial Pt-C catalyst. The results show that the electrocatalytic activity of BOMC is significantly higher than that of other used catalysts. PMID:24910045

  16. Ordered mesoporous carbon/Nafion as a versatile and selective solid-phase microextraction coating.

    PubMed

    Zeng, Jingbin; Zhao, Cuiying; Chen, Jingjing; Subhan, Fazle; Luo, Liwen; Yu, Jianfeng; Cui, Bingwen; Xing, Wei; Chen, Xi; Yan, Zifeng

    2014-10-24

    In this study, ordered mesoporous carbon (OMC) with large surface area (1019m(2)g(-1)), uniform mesoporous structure (pore size distribution centering at 4.2nm) and large pore volume (1.46cm(3)g(-1)) was synthesized using 2D hexagonally mesoporous silica MSU-H as the hard template and sucrose as the carbon precursor. The as-synthesized OMC was immobilized onto a stainless steel wire using Nafion as a binder to prepare an OMC/Nafion solid-phase microextraction (SPME) coating. The extraction characteristics of the OMC/Nafion coating were extensively investigated using a wide range of analytes including non-polar (light petroleum and benzene homologues) and polar compounds (amines and phenols). The OMC/Nafion coating exhibited much better extraction efficiency towards all selected analytes than that of a multi-walled carbon nanotubes/Nafion coating with similar length and thickness, which is ascribed to its high surface area, well-ordered mesoporous structure and large pore volume. When the OMC/Nafion coating was used to extract a mixture containing various kinds of analytes, it possessed excellent extraction selectivity towards aromatic non-polar compounds. In addition, the feasibility of the OMC/Nafion coating for application in electrochemically enhanced SPME was demonstrated using protonated amines as model analytes. PMID:25249487

  17. A reconstruction strategy to synthesize mesoporous SAPO molecular sieve single crystals with high MTO catalytic activity.

    PubMed

    Wang, Chan; Yang, Miao; Li, Mingrun; Xu, Shutao; Yang, Yue; Tian, Peng; Liu, Zhongmin

    2016-05-11

    Mesoporous SAPO-34 single crystals with tunable porosity and Si content have been fast synthesized within 4 hours by a reconstruction strategy, which show excellent hydrothermal stability and MTO catalytic activity. This new strategy is further proven to be applicable to prepare other mesoporous SAPO molecular sieve single crystals. PMID:27101359

  18. Pyrolytic Synthesis of Carbon Nanotubes from Sucrose on a Mesoporous Silicate

    NASA Technical Reports Server (NTRS)

    Abdel-Fattah, Tarek; Siochi, Mia; Crooks, Roy

    2005-01-01

    Multiwall carbon nanotubes were synthesized from sucrose by a pyrolytic technique using mesoporous MCM-41 silicate templates without transition metal catalysts. The Nanotubes were examined in the carbon/silicate composite and after dissolution of the silicate. High resolution transmission electron microscopy study of the multiwall nanotubes showed them to be 15 nm in diameter, 200 nm in length and close-ended. There was variation in crystallinity with some nanotubes showing disordered wall structures.

  19. Ordered Mesoporous CMK-5 Carbon with Ultra-Thin Pore Walls and Highly Dispersed Nickel Nanoparticles

    SciTech Connect

    Fulvio, Pawquale F; Liang, Chengdu; Dai, Sheng; Jaroniec, Mietek

    2009-01-01

    Ordered mesoporous CMK-5 carbons with ultra-thin carbon pore walls and highly dispersed Ni nanoparticles have been successfully prepared by using two different SBA-15 silicas as hard templates and 2, 3-di-hydroxynaphtalene (DHN) as a carbon precursor. The nickel precursor was a concentrated nickel nitrate hexahydrate [Ni(NO3)2.6H2O] solution in isopropanol added to the carbon-silica nanocomposites prior to thermal treatments. The samples studied were analyzed by thermogravimetry (TG), nitrogen adsorption at -196 C, powder X-ray diffraction (XRD), Raman spectroscopy, scanning and transmission electron microscopy (STEM) and in situ electron diffraction X-ray spectroscopy (EDX). While TG revealed carbon contents lower than 30 wt%, nitrogen adsorption provided information about homogeneity of carbon thin film deposited onto mesopore walls of ordered silica templates, SBA-15. The templates, carbon-silica nanocomposites and carbon inverse replicas with nickel nanoparticles exhibited uniform pores, high surface areas and large pore volumes. Graphitic carbon was identified by the presence of a characteristic G band on Raman spectra, whereas the diffraction peak attributed to the stacking of graphene planes was not observed by powder XRD.The presence of ordered domains in the carbon materials studied was confirmed by small angle XRD and STEM imaging. In addition, the STEM images revealed that the nickel nanoparticles were uniform in size, ~3nm, and were homogeneously dispersed within ordered tubular carbon walls. A few larger clusters of nickel, ~60nm, present on the external surface, were identified by powder XRD as metallic Ni. The in situ EDX revealed that the small nanoparticles were largely composed of Ni with traces of NiO. Similar nanoparticles dispersions have been reported only for Ni-containing multi-walled carbon nanotubes (CNTs), whereas previously reported ordered mesoporous carbons possessed larger Ni/NiO nanoparticles within CMK-3 nanostructure.

  20. Metallic WO2-Carbon Mesoporous Nanowires as Highly Efficient Electrocatalysts for Hydrogen Evolution Reaction.

    PubMed

    Wu, Rui; Zhang, Jingfang; Shi, Yanmei; Liu, Dali; Zhang, Bin

    2015-06-10

    The development of electrocatalysts to generate hydrogen, with good activity and stability, is a great challenge in the fields of chemistry and energy. Here we demonstrate a "hitting three birds with one stone" method to synthesize less toxic metallic WO2-carbon mesoporous nanowires with high concentration of oxygen vacancies (OVs) via calcination of inorganic/organic WO3-ethylenediamine hybrid precursors. The products exhibit excellent performance for H2 generation: the onset overpotential is only 35 mV, the required overpotentials for 10 and 20 mA/cm(2) are 58 and 78 mV, the Tafel slope is 46 mV/decade, the exchange current density is 0.64 mA/cm(2), and the stability is over 10 h. Further studies, in combination with density functional theory, demonstrate that the unusual electronic structure and the large amount of active sites, generated by the high concentration of OVs, as well as the closely attached carbon materials, were key factors for excellent performance. Our results experimentally and theoretically establish metallic transition metal oxides (TMOs) as intriguing novel electrocatalysts for H2 generation. Such TMOs with OVs might be promising candidates for other energy storage and conversion applications. PMID:25992910

  1. Preparation of porous diatomite-templated carbons with large adsorption capacity and mesoporous zeolite K-H as a byproduct.

    PubMed

    Liu, Dong; Yuan, Weiwei; Deng, Liangliang; Yu, Wenbin; Sun, Hongjuan; Yuan, Peng

    2014-06-15

    In this study, KOH activation was performed to enhance the porosity of the diatomite-templated carbon and to increase its adsorption capacity of methylene blue (MB). In addition to serving as the activation agent, KOH was also used as the etchant to remove the diatomite templates. Zeolite K-H was synthesized as a byproduct via utilization of the resultant silicon- and potassium-containing solutions created from the KOH etching of the diatomite templates. The obtained diatomite-based carbons were composed of macroporous carbon pillars and tubes, which were derived from the replication of the diatomite templates and were well preserved after KOH activation. The abundant micropores in the walls of the carbon pillars and tubes were derived from the break and reconfiguration of carbon films during both the removal of the diatomite templates and KOH activation. Compared with the original diatomite-templated carbons and CO2-activated carbons, the KOH-activated carbons had much higher specific surface areas (988 m(2)/g) and pore volumes (0.675 cm(3)/g). Moreover, the KOH-activated carbons possessed larger MB adsorption capacity (the maximum Langmuir adsorption capacity: 645.2 mg/g) than those of the original carbons and CO2-activated carbons. These results showed that KOH activation was a high effective activation method. The zeolite K-H byproduct was obtained by utilizing the silicon- and potassium-containing solution as the silicon and potassium sources. The zeolite exhibited a stick-like morphology and possessed nanosized particles with a mesopore-predominant porous structure which was observed by TEM for the first time. PMID:24767493

  2. Mesoporous silica nanospheres decorated with CdS nanocrystals for enhanced photocatalytic and excellent antibacterial activities

    NASA Astrophysics Data System (ADS)

    Hu, Jin-Lin; Yang, Qi-Hao; Lin, He; Ye, Yu-Pei; He, Qiao; Zhang, Jie-Ni; Qian, Hai-Sheng

    2013-06-01

    Uniform SiO2@CdS mesoporous nanospheres with an average diameter of 300 nm have been synthesized successfully by a facile process. The as-prepared mesoporous composite nanospheres have a BET-specific surface area of 640 m2 g-1 and an average pore size of 2.82 nm. The results demonstrated that more than 60% Rhodamine B (RhB) dye in solution (4.8 mg L-1, 50 mL) could be removed by adsorption in the dark for 30 min using the as-prepared SiO2@CdS mesoporous nanospheres (40 mg). The as-prepared SiO2@CdS mesoporous nanospheres have a mesoporous nanostructure, suggesting a higher specific surface area and resulting in a strong adsorption ability. In addition, the mesoporous silica was decorated with ca. 5 nm CdS nanocrystals, which showed excellent photocatalytic activity under visible light and could rapidly remove most of the RhB molecules from a pollutant solution under visible light irradiation. Furthermore, the mesoporous SiO2@CdS nanospheres synthesized by the present protocol exhibited excellent antibacterial activity.Uniform SiO2@CdS mesoporous nanospheres with an average diameter of 300 nm have been synthesized successfully by a facile process. The as-prepared mesoporous composite nanospheres have a BET-specific surface area of 640 m2 g-1 and an average pore size of 2.82 nm. The results demonstrated that more than 60% Rhodamine B (RhB) dye in solution (4.8 mg L-1, 50 mL) could be removed by adsorption in the dark for 30 min using the as-prepared SiO2@CdS mesoporous nanospheres (40 mg). The as-prepared SiO2@CdS mesoporous nanospheres have a mesoporous nanostructure, suggesting a higher specific surface area and resulting in a strong adsorption ability. In addition, the mesoporous silica was decorated with ca. 5 nm CdS nanocrystals, which showed excellent photocatalytic activity under visible light and could rapidly remove most of the RhB molecules from a pollutant solution under visible light irradiation. Furthermore, the mesoporous SiO2@CdS nanospheres synthesized by the present protocol exhibited excellent antibacterial activity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01329d

  3. Modeling high-temperature diffusion of gases in micro and mesoporous amorphous carbon

    NASA Astrophysics Data System (ADS)

    Ranganathan, Raghavan; Rokkam, Srujan; Desai, Tapan; Keblinski, Pawel; Cross, Peter; Burnes, Richard

    2015-08-01

    In this work, we study diffusion of gases in porous amorphous carbon at high temperatures using equilibrium molecular dynamics simulations. Microporous and mesoporous carbon structures are computationally generated using liquid quench method and reactive force fields. Motivated by the need to understand high temperature diffusivity of light weight gases like H2, O2, H2O, and CO in amorphous carbon, we investigate the diffusion behavior as function of two important parameters: (a) the pore size and (b) the concentration of diffusing gases. The effect of pore size on diffusion is studied by employing multiple realizations of the amorphous carbon structures in microporous and mesoporous regimes, corresponding to densities of 1 g/cm3 and 0.5 g/cm3, respectively. A detailed analysis of the effect of gas concentration on diffusion in the context of these two porosity regimes is presented. For the microporous structure, we observe that predominantly, a high diffusivity results when the structure is highly anisotropic and contains wide channels between the pores. On the other hand, when the structure is highly homogeneous, significant molecule-wall scattering leads to a nearly concentration-independent behavior of diffusion (reminiscent of Knudsen diffusion). The mesoporous regime is similar in behavior to the highly diffusive microporous carbon case in that diffusion at high concentration is governed by gas-gas collisions (reminiscent of Fickian diffusion), which transitions to a Knudsen-like diffusion at lower concentration.

  4. Novel mesoporous P-doped graphitic carbon nitride nanosheets coupled with ZnIn2S4 nanosheets as efficient visible light driven heterostructures with remarkably enhanced photo-reduction activity

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Liu, Tian-Yu; Huang, Ting; Liu, Xiao-Heng; Yang, Xu-Jie

    2016-02-01

    In this report, we rationally designed and fabricated P-C3N4/ZnIn2S4 nanocomposites by in situ immobilizing ZnIn2S4 nanosheets onto the surface of mesoporous P-doped graphite carbon nitrogen (P-C3N4) nanosheets in a mixed solvothermal environment; their application to the photoreduction of 4-nitroaniline was used to estimate the photocatalytic performance. Different to the template route, here the mesoporous P-C3N4 nanosheets were prepared with a template-free strategy. The as-fabricated P-C3N4/ZnIn2S4 nanocomposites were systematically characterized by analyzing the phase structure, chemical components, electronic and optical properties and separation of charge carrier pairs. More importantly, these P-C3N4/ZnIn2S4 heterostructures have been proven to be highly efficient visible light responsive photocatalysts for photo-reduction, and meanwhile exhibit excellent photo-stability during recycling runs. The sufficient evidence reveals that the significantly improved photocatalytic performance is mainly attributed to the more efficient charge carrier separation based on the construction of a close heterogeneous interface. This work may provide new insights into the utilization of P-C3N4/ZnIn2S4 nanocomposites as visible light driven photocatalysts for comprehensive organic transformations in the field of fine chemical engineering.In this report, we rationally designed and fabricated P-C3N4/ZnIn2S4 nanocomposites by in situ immobilizing ZnIn2S4 nanosheets onto the surface of mesoporous P-doped graphite carbon nitrogen (P-C3N4) nanosheets in a mixed solvothermal environment; their application to the photoreduction of 4-nitroaniline was used to estimate the photocatalytic performance. Different to the template route, here the mesoporous P-C3N4 nanosheets were prepared with a template-free strategy. The as-fabricated P-C3N4/ZnIn2S4 nanocomposites were systematically characterized by analyzing the phase structure, chemical components, electronic and optical properties and separation of charge carrier pairs. More importantly, these P-C3N4/ZnIn2S4 heterostructures have been proven to be highly efficient visible light responsive photocatalysts for photo-reduction, and meanwhile exhibit excellent photo-stability during recycling runs. The sufficient evidence reveals that the significantly improved photocatalytic performance is mainly attributed to the more efficient charge carrier separation based on the construction of a close heterogeneous interface. This work may provide new insights into the utilization of P-C3N4/ZnIn2S4 nanocomposites as visible light driven photocatalysts for comprehensive organic transformations in the field of fine chemical engineering. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07695a

  5. A nitrogen-doped mesoporous carbon containing an embedded network of carbon nanotubes as a highly efficient catalyst for the oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Li, Jin-Cheng; Zhao, Shi-Yong; Hou, Peng-Xiang; Fang, Ruo-Pian; Liu, Chang; Liang, Ji; Luan, Jian; Shan, Xu-Yi; Cheng, Hui-Ming

    2015-11-01

    A nitrogen-doped mesoporous carbon containing a network of carbon nanotubes (CNTs) was produced for use as a catalyst for the oxygen reduction reaction (ORR). SiO2 nanoparticles were decorated with clusters of Fe atoms to act as catalyst seeds for CNT growth, after which the material was impregnated with aniline. After polymerization of the aniline, the material was pyrolysed and the SiO2 was removed by acid treatment. The resulting carbon-based hybrid also contained some Fe from the CNT growth catalyst and was doped with N from the aniline. The Fe-N species act as active catalytic sites and the CNT network enables efficient electron transport in the material. Mesopores left by the removal of the SiO2 template provide short transport pathways and easy access to ions. As a result, the catalyst showed not only excellent ORR activity, with 59 mV more positive onset potential and 30 mV more positive half-wave potential than a Pt/C catalyst, but also much longer durability and stronger tolerance to methanol crossover than a Pt/C catalyst.A nitrogen-doped mesoporous carbon containing a network of carbon nanotubes (CNTs) was produced for use as a catalyst for the oxygen reduction reaction (ORR). SiO2 nanoparticles were decorated with clusters of Fe atoms to act as catalyst seeds for CNT growth, after which the material was impregnated with aniline. After polymerization of the aniline, the material was pyrolysed and the SiO2 was removed by acid treatment. The resulting carbon-based hybrid also contained some Fe from the CNT growth catalyst and was doped with N from the aniline. The Fe-N species act as active catalytic sites and the CNT network enables efficient electron transport in the material. Mesopores left by the removal of the SiO2 template provide short transport pathways and easy access to ions. As a result, the catalyst showed not only excellent ORR activity, with 59 mV more positive onset potential and 30 mV more positive half-wave potential than a Pt/C catalyst, but also much longer durability and stronger tolerance to methanol crossover than a Pt/C catalyst. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05998d

  6. Microwave synthesis and electrochemical characterization of mesoporous carbon@Bi{sub 2}O{sub 3} composites

    SciTech Connect

    Xia, Nannan; Yuan, Dingsheng; Zhou, Tianxiang; Chen, Jingxing; Mo, Shanshan; Liu, Yingliang

    2011-05-15

    Graphical abstract: An efficient and quick microwave method has been employed to prepare worm-like mesoporous carbon@Bi{sub 2}O{sub 3} composites for the first time. The electrochemical measurement shows the worm-like mesoporous carbon@Bi{sub 2}O{sub 3} composites exhibits excellent capacitance performance and the maximum specific capacitance is up to 386 F g{sup -1}. Research highlights: {yields} An efficient and quick microwave method has been employed. {yields} A worm-like mesoporous carbon@Bi{sub 2}O{sub 3} composites have been successfully prepared. {yields} This composite exhibits excellent capacitance performance. {yields} This composite could be a potential electrode material for the supercapacitors. -- Abstract: An efficient and quick microwave method has been employed to prepare worm-like mesoporous carbon@Bi{sub 2}O{sub 3} composites for the first time. As-prepared products have been characterized by X-ray diffraction, N{sub 2} adsorption-desorption, scanning electron microscopy, transmission electron microscopy and inductive coupled plasma atomic emission spectroscopy. The electrochemical measurement shows the worm-like mesoporous carbon@Bi{sub 2}O{sub 3} composites exhibits excellent capacitance performance and the maximum specific capacitance reaches 386 F g{sup -1}, three times more than the pure worm-like mesoporous carbon.

  7. Nanocomposites of palladium nanoparticle-loaded mesoporous carbon nanospheres for the electrochemical determination of hydrogen peroxide.

    PubMed

    Bian, Xiaojun; Guo, Kai; Liao, Lei; Xiao, Jingjing; Kong, Jilie; Ji, Chang; Liu, Baohong

    2012-09-15

    Palladium nanoparticles (Pd NPs) were loaded in situ on novel mesoporous carbon nanospheres (MCNs), which possess high specific surface area and large pore volume. The resulting Pd/MCNs hybrid nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). By using Pd/MCNs as the catalyst matrices to modify the surface of glassy carbon electrode, a nonenzymatic sensor was developed for the determination of hydrogen peroxide (H(2)O(2)). Cyclic voltammetry (CV) and amperometry (at an applied potential of -0.30 V versus SCE) were used to study and optimize the performance of the electrochemical sensor. It was demonstrated that the sensor not only exhibits good electrocatalytic activity toward the reduction of H(2)O(2) but also has high sensitivity (307.5 μA mM(-1) cm(-2)), low detection limit of 1.0 μM, and wide linear response range from 7.5 μM to 10 mM. Moreover, the sensor shows excellent stability and anti-interference capability for the detection of H(2)O(2). PMID:22967549

  8. Well-dispersed Pt nanoparticles on polydopamine-coated ordered mesoporous carbons and their electrocatalytic application.

    PubMed

    Yan, Lijiao; Bo, Xiangjie; Zhu, Dongxia; Guo, Liping

    2014-03-01

    Polydopamine (PDA)-coated ordered mesoporous carbons (OMCs) are easily prepared through one-step self-polymerization of dopamine on OMCs matrix at room temperature. Pt nanoparticles (NPs) are deposited on OMCs-PDA via a simple chemical reduction. The PDA layer helps to improve the water-solubility and dispersibility of OMCs, and plays a key role in the deposition of uniform and well-distributed Pt NPs. Transmission electron microscopy images reveal that the ultra-fine Pt NPs with an average size of ~1.8 nm are well-dispersed on the surface of OMCs-PDA. The electrocatalytic behavior of OMCs-PDA/Pt modified glassy carbon (GC) electrode is investigated by cyclic voltammetry and current-time methods using hydrogen peroxide (H2O2) and hydrazine (N2H4) as redox probes. Results show that OMCs-PDA/Pt exhibits improved electrocatalytic activity towards H2O2 reduction and N2H4 oxidation compared with OMCs/Pt. The linear electro-redox responses are found for H2O2 and N2H4 in the range of 2-14324 μM and 1-229 μM with the detection limit (S/N=3) of 0.85 μM and 0.51 μM, respectively. In addition, this new nanocomposite modified electrode exhibits high sensitivity, good anti-interference ability, excellent reproducibility and long-term stability. PMID:24468374

  9. Bismuth Entrapped in Mesoporous Carbon for the Simultaneous Measurement of Pb, Cd and Zn.

    PubMed

    Hu, Xin; Miao, Yuqing; Zhou, Shilin; Liang, Xiaocai

    2015-01-01

    Here we report a Bi/mesoporous carbon modified glass carbon electrode (Bi-MC-GCE) for the detection of heavy metal ions Zn, Cd and Pb. Bi(NO3)3 was firstly entrapped into the holes of MCs by sonicating them together in solution. Then the dispersed mixture was pipetted onto the surface of GCE and left to dry. Bi(NO3)3 in the holes of MCs was reduced to metallic Bi during the process of deposition for square wave stripping analysis. The obtained Bi-MC-GCE exhibits significantly enhanced sensitivity for Zn, Cd and Pb detection compared to blank GCE, bismuth or MC alone modified GCE, which is attributed to the high specific surface area of MCs and the increased amount of entrapped bismuth as active sites for the deposition and stripping of heavy metal ions. A linearship is observed for the concentration of Zn, Cd, and Pb from 10 to 110 ppb. The relative standard deviation was 3.7% for Zn, 3% for Cd and 8% for Pb at the 90 ppb level (n = 3). The suggested Bi-MC-GCE exhibits a potential application for real water sample analysis. PMID:26328415

  10. 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. PMID:25989157

  11. Facile synthesis of magnetic mesoporous hollow carbon microspheres for rapid capture of low-concentration peptides.

    PubMed

    Cheng, Gong; Zhou, Ming-Da; Zheng, Si-Yang

    2014-08-13

    Mesoporous and hollow carbon microspheres embedded with magnetic nanoparticles (denoted as MHM) were prepared via a facile self-sacrificial method for rapid capture of low-abundant peptides from complex biological samples. The morphology, structure, surface property, and magnetism were well-characterized. The hollow magnetic carbon microspheres have a saturation magnetization value of 130.2 emu g(-1) at room temperature and a Brunauer-Emmett-Teller specific surface area of 48.8 m(2) g(-1) with an average pore size of 9.2 nm for the mesoporous carbon shell. The effectiveness of these MHM affinity microspheres for capture of low-concentration peptides was evaluated by standard peptides, complex protein digests, and real biological samples. These multifunctional hollow carbon microspheres can realize rapid capture and convenient separation of low-concentration peptides. They were validated to have better performance than magnetic mesoporous silica and commercial peptide-enrichment products. In addition, they can be easily recycled and present excellent reusability. Therefore, it is expected that this work may provide a promising tool for high-throughput discovery of peptide biomarkers from biological samples for disease diagnosis and other biomedical applications. PMID:24992375

  12. 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. PMID:24997254

  13. Facile Synthesis of Magnetic Mesoporous Hollow Carbon Microspheres for Rapid Capture of Low-Concentration Peptides

    PubMed Central

    2015-01-01

    Mesoporous and hollow carbon microspheres embedded with magnetic nanoparticles (denoted as MHM) were prepared via a facile self-sacrificial method for rapid capture of low-abundant peptides from complex biological samples. The morphology, structure, surface property, and magnetism were well-characterized. The hollow magnetic carbon microspheres have a saturation magnetization value of 130.2 emu g–1 at room temperature and a Brunauer–Emmett–Teller specific surface area of 48.8 m2 g–1 with an average pore size of 9.2 nm for the mesoporous carbon shell. The effectiveness of these MHM affinity microspheres for capture of low-concentration peptides was evaluated by standard peptides, complex protein digests, and real biological samples. These multifunctional hollow carbon microspheres can realize rapid capture and convenient separation of low-concentration peptides. They were validated to have better performance than magnetic mesoporous silica and commercial peptide-enrichment products. In addition, they can be easily recycled and present excellent reusability. Therefore, it is expected that this work may provide a promising tool for high-throughput discovery of peptide biomarkers from biological samples for disease diagnosis and other biomedical applications. PMID:24992375

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

    PubMed

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

    2016-03-01

    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. PMID:26833434

  15. Nitrogen-doped mesoporous carbon for energy storage in vanadium redox flow batteries

    SciTech Connect

    Shao, Yuyan; Wang, Xiqing; Engelhard, Mark H.; Wang, Chong M.; Dai, Sheng; Liu, Jun; Yang, Zhenguo; Lin, Yuehe

    2010-03-22

    We demonstrate a novel electrode material―nitrogen-doped mesoporous carbon (NMC)―for vanadium redox flow batteries. Mesoporous carbon (MC) is prepared using a soft-template method and doped with nitrogen by heat-treating MC in NH3. NMC is characterized with X-ray photoelectron spectroscopy and transmission electron microscopy. The redox reaction of VO2+/VO2+ is characterized with cyclic voltammetry and electrochemical impedance spectroscopy. The electrocatalytic kinetics of the redox couple VO2+/VO2+ is significantly enhanced on NMC electrode compared with MC and graphite electrodes. The reversibility of the redox couple VO2+/VO2+ is greatly improved on NMC (0.61 for NMC vs. 0.34 for graphite). Nitrogen doping facilitates the electron transfer on the electrode/electrolyte interface for both oxidation and reduction processes. NMC is a promising electrode material for redox flow batteries.

  16. An active carbon catalyst prevents coke formation from asphaltenes during the hydrocracking of vacuum residue

    SciTech Connect

    Fukuyama, H.; Terai, S.

    2007-07-01

    Active carbons were prepared by the steam activation of a brown coal char. The active carbon with mesopores showed greater adsorption selectivity for asphaltenes. The active carbon was effective at suppressing coke formation, even with the high hydrocracking conversion of vacuum residue. The analysis of the change in the composition of saturates, aromatics, resins, and asphaltenes in the cracked residue with conversion demonstrated the ability of active carbon to restrict the transformation of asphaltenes to coke. The active carbon that was richer in mesopores was presumably more effective at providing adsorption sites for the hydrocarbon free-radicals generated initially during thermal cracking to prevent them from coupling and polycondensing.

  17. Fabrication and characterization of a zirconia/multi-walled carbon nanotube mesoporous composite.

    PubMed

    Wang, Zonghua; Xia, Jianfei; Xia, Yanzhi; Lu, Caiyu; Shi, Guoyu; Zhang, Feifei; Zhu, Fuqiang; Li, Yanhui; Xia, Linhua; Tang, Jie

    2013-10-01

    A zirconia/multi-walled carbon nanotube (ZrO2/MWCNT) mesoporous composite was fabricated via a simple method using a hydrothermal process with the aid of the cationic surfactant cetyltrimethylammonium bromide (CTAB). Transmission electron microscopy (TEM), N2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques were used to characterize the as-made samples. The cubic ZrO2 nanocrystallites were observed to overlay the surface of MWCNTs, which resulted in the formation of a novel mesoporous-nanotube composite. On the basis of a TEM analysis of the products from controlled experiment, the role of the acid-treated MWCNTs and CTAB was proposed to explain the formation of the mesoporous-nanotube structure. The as-made composite possessed novel properties, such as a high surface area (312 m(2)·g(-1)) and a bimodal mesoporous structure (3.18 nm and 12.4 nm). It was concluded that this composite has important application value due to its one-dimensional hollow structure, excellent electric conductivity and large surface area. PMID:23910298

  18. Photochemistry of single wall carbon nanotubes embedded in a mesoporous silica matrix.

    PubMed

    Alvaro, Mercedes; Atienzar, Pedro; Bourdelande, José L; García, Hermenegildo

    2002-12-21

    By embedding single wall carbon nanotubes in a mesoporous silica matrix (SWNT@SiO2) the photochemical properties have been measured upon laser excitation at 266 nm; the SWNT@SiO2 exhibits long-lived emission (lambda em = 400 nm, tau = 0.95 microsecond), transient absorption (lambda max = 390 nm, tau = 11 microseconds) and is able to generate singlet oxygen in D2O. PMID:12536788

  19. Effect of carbon doping on the mesoporous structure of nanocrystalline titanium dioxide and its solar-light-driven photocatalytic degradation of NOx.

    PubMed

    Huang, Yu; Ho, Wingkei; Lee, Shuncheng; Zhang, Lizhi; Li, Guisheng; Yu, Jimmy C

    2008-04-01

    Effective mesoporous nanocrystalline C-doped TiO(2) photocatalysts were synthesized through a direct solution-phase carbonization using titanium tetrachloride and diethanolamine as precursors. X-ray photoelectron spectroscopy (XPS) results revealed that oxygen sites in the TiO(2) lattice were substituted by carbon atoms and formed a C-Ti-O-C structure. The absorption region of the as-prepared TiO(2) was extended to the visible light region in view of the substitution for oxygen sites by carbon atoms. The photocatalytic activities of the as-prepared samples were tested in a flow system on the degradation of NO at typical indoor air levels under simulated solar-light irradiation. The samples showed a more effective removal efficiency than commercial photocatalyst (P25) on the degradation of the common indoor pollutant NO. The parameters significantly affecting the mesoporous structure and removal efficiency on indoor air were also investigated. PMID:18290683

  20. Surfactant-Free Assembly of Mesoporous Carbon Hollow Spheres with Large Tunable Pore Sizes.

    PubMed

    Zhang, Hongwei; Noonan, Owen; Huang, Xiaodan; Yang, Yannan; Xu, Chun; Zhou, Liang; Yu, Chengzhong

    2016-04-26

    Mesoporous carbon hollow spheres (MCHS) have wide applications, including catalysis, absorption, and energy storage/conversion. Herein, we report a one-pot, surfactant-free synthesis of MCHS using three molecules: resorcinol, formaldehyde, and tetrapropyl orthosilicate. The co-condensation process between the in situ generated silica primary particles and the polymer oligomers is regulated, leading to monodispersed MCHS with adjustable pore sizes from micropores to 13.9 nm. The resultant MCHS shows excellent performance for electrochemical double-layer capacitors with high capacitance (310 F g(-1) at 1 A g(-1)), excellent rate capability (157 F g(-1) at 50 A g(-1)), and outstanding cycling stability (98.6% capacity retention after 10 000 cycles at 10 A g(-1)). Our one-pot synthesis strategy is versatile and can be extended to fabricate metal oxide@mesoporous carbon yolk-shell structures in the absence of surfactant, paving the way toward designed synthesis of nanostructured mesoporous carbon composites for various applications. PMID:27050771

  1. Adsorption equilibrium, kinetics and thermodynamics of dichloroacetic acid from aqueous solution using mesoporous carbon.

    PubMed

    Ding, Ying; Zhu, Jianzhong; Cao, Yang; Chen, Shenglu

    2014-08-01

    The presence of disinfection by-products, such as trihalomethanes and haloacetic acids in water, is believed to be harmful to human health. In this work, mesoporous carbon was synthesized with the evaporation-induced self-assembly method and employed to evaluate the effects of initial concentration, contact time, pH and temperature on the removal of dichloroacetic acid in batch experiments. Adsorption equilibrium was established in 480 min and the maximum adsorption (350mg/g) of dichloroacetic acid on the mesoporous carbon was observed to occur at 308 K and pH 3.0. Freundlich and Langmuir isotherms were used to analyse the equilibrium data at different temperatures; kinetic data were fitted to the pseudo-first-order and pseudo-second-order models and found that the adsorption capacity, mass transfer coefficient and diffusivity of dichloroacetic acid were directly affected by the physical and chemical parameters. In addition, the various thermodynamic parameters, such as Gibbs free energy (Delta G), enthalpy (Delta H = 54.35 kJmol-1) and entropy (Delta S = 258.36 Jmol-1 K-1) were calculated to analyse the adsorption process. The experimental results indicated that the mesoporous carbon was an excellent adsorbent for dichloroacetic acid removal from aqueous solutions. PMID:24956790

  2. Hyaluronic acid modified mesoporous carbon nanoparticles for targeted drug delivery to CD44-overexpressing cancer cells.

    PubMed

    Wan, Long; Jiao, Jian; Cui, Yu; Guo, Jingwen; Han, Ning; Di, Donghua; Chang, Di; Wang, Pu; Jiang, Tongying; Wang, Siling

    2016-04-01

    In this paper, hyaluronic acid (HA) functionalized uniform mesoporous carbon spheres (UMCS) were synthesized for targeted enzyme responsive drug delivery using a facile electrostatic attraction strategy. This HA modification ensured stable drug encapsulation in mesoporous carbon nanoparticles in an extracellular environment while increasing colloidal stability, biocompatibility, cell-targeting ability, and controlled cargo release. The cellular uptake experiments of fluorescently labeled mesoporous carbon nanoparticles, with or without HA functionalization, demonstrated that HA-UMCS are able to specifically target cancer cells overexpressing CD44 receptors. Moreover, the cargo loaded doxorubicin (DOX) and verapamil (VER) exhibited a dual pH and hyaluronidase-1 responsive release in the tumor microenvironment. In addition, VER/DOX/HA-UMCS exhibited a superior therapeutic effect on an in vivo HCT-116 tumor in BALB/c nude mice. In summary, it is expected that HA-UMCS will offer a new method for targeted co-delivery of drugs to tumors overexpressing CD44 receptors. PMID:26901756

  3. Mesoporous wormholelike carbon with controllable nanostructure for lithium ion batteries application

    SciTech Connect

    Yang, Xiaoqing; Li, Xinxi; Li, Zhenghui; Zhang, Guoqing; Wu, Dingcai

    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 high 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.

  4. Nitrogen-doped ordered cubic mesoporous carbons as metal-free counter electrodes for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Chen, Ming; Shao, Leng-Leng; Liu, Yu-Ping; Ren, Tie-Zhen; Yuan, Zhong-Yong

    2015-06-01

    N-doped ordered cubic mesoporous carbons (N-OCMCs) are synthesized by a one-pot aqueous route from resorcinol and hexamethylenetetramine (HMT) and applied as counter electrode (CE) materials for dye-sensitized solar cells (DSSCs). The prepared N-OCMCs with ordered cubic mesoporous structure and large surface area offer appropriate electrolyte ions diffusion channels and abundant catalytically active sites for triiodide reduction. Moreover, the temperature dependence of nitrogen content and the nitrogen-doped types are demonstrated to play decisive roles in regulating the electrocatalytic activity of N-OCMC CEs and affecting the photovoltaic performance of DSSCs. The DSSCs based on the N-OCMC CEs achieve an optimum power conversion efficiency of 5.60%, as high as 86.7% of the cell based on the traditional Pt CE, due to that high N-doping amount, and particularly favorable pyridinic-N and graphtitic-N types promote the charge transport and transfer process of the carbon CE. The good catalytic performance could render N-OCMC as a cost-effective CE candidate to Pt in DSSC.

  5. Amperometric hydrogen peroxide and glucose biosensor based on NiFe2/ordered mesoporous carbon nanocomposites.

    PubMed

    Xiang, Dong; Yin, Longwei; Ma, Jingyun; Guo, Enyan; Li, Qun; Li, Zhaoqiang; Liu, Kegao

    2015-01-21

    Nanocomposites of NiFex embedded in ordered mesoporous carbon (OMC) (x = 0, 1, 2) were prepared by a wet impregnation and hydrogen reduction process and were used to construct electrochemical biosensors for the amperometric detection of hydrogen peroxide (H2O2) or glucose. The NiFe2/OMC nanocomposites were demonstrated to have a large surface area, suitable mesoporous channels, many edge-plane-like defective sites, and a good distribution of alloyed nanoparticles. The NiFe2/OMC and Nafion modified glass carbon electrode (GCE) exhibited excellent electrocatalytic activities toward the reduction of H2O2 as well. By utilizing it as a bioplatform, GOx (glucose oxidase) cross-linked with Nafion was immobilized on the surface of the electrode for the construction of an amperometric glucose biosensor. Our results indicated that the amperometric hydrogen peroxide biosensor (NiFe2/OMC + Nafion + GCE) showed good analytical performances in term of a high sensitivity of 4.29 μA mM(-1) cm(-2), wide linearity from 6.2 to 42,710 μM and a low detection limit of 0.24 μM at a signal-to-noise ratio of 3 (S/N = 3). This biosensor exhibited excellent selectivity, high stability and negligible interference for the detection of H2O2. In addition, the immobilized enzyme on NiFe2/OMC + Nafion + GCE, retaining its bioactivity, exhibited a reversible two-proton and two-electron transfer reaction, a fast heterogeneous electron transfer rate and an effective Michaelis-Menten constant (K) (3.18 mM). The GOx + NiFe2/OMC + Nafion + GCE could be used to detect glucose based on the oxidation of glucose catalyzed by GOx and exhibited a wide detection range of 48.6-12,500 μM with a high sensitivity of 6.9 μA mM(-1) cm(-2) and a low detection limit of 2.7 μM (S/N = 3). The enzymic biosensor maintained a high selectivity and stability features, and shows great promise for application in the detection of glucose. PMID:25429370

  6. Two-dimensional mesoporous carbon nanosheets and their derived graphene nanosheets: synthesis and efficient lithium ion storage.

    PubMed

    Fang, Yin; Lv, Yingying; Che, Renchao; Wu, Haoyu; Zhang, Xuehua; Gu, Dong; Zheng, Gengfeng; Zhao, Dongyuan

    2013-01-30

    We report a new solution deposition method to synthesize an unprecedented type of two-dimensional ordered mesoporous carbon nanosheets via a controlled low-concentration monomicelle close-packing assembly approach. These obtained carbon nanosheets possess only one layer of ordered mesopores on the surface of a substrate, typically the inner walls of anodic aluminum oxide pore channels, and can be further converted into mesoporous graphene nanosheets by carbonization. The atomically flat graphene layers with mesopores provide high surface area for lithium ion adsorption and intercalation, while the ordered mesopores perpendicular to the graphene layer enable efficient ion transport as well as volume expansion flexibility, thus representing a unique orthogonal architecture for excellent lithium ion storage capacity and cycling performance. Lithium ion battery anodes made of the mesoporous graphene nanosheets have exhibited an excellent reversible capacity of 1040 mAh/g at 100 mA/g, and they can retain at 833 mAh/g even after numerous cycles at varied current densities. Even at a large current density of 5 A/g, the reversible capacity is retained around 255 mAh/g, larger than for most other porous carbon-based anodes previously reported, suggesting a remarkably promising candidate for energy storage. PMID:23282081

  7. Mesoporous Carbon Nanofibers Embedded with MoS2 Nanocrystals for Extraordinary Li-Ion Storage.

    PubMed

    Hu, Shan; Chen, Wen; Uchaker, Evan; Zhou, Jing; Cao, Guozhong

    2015-12-01

    MoS2 nanocrystals embedded in mesoporous carbon nanofibers are synthesized through an electrospinning process followed by calcination. The resultant nanofibers are 100-150 nm in diameter and constructed from MoS2 nanocrystals with a lateral diameter of around 7 nm with specific surface areas of 135.9 m(2)  g(-1) . The MoS2 @C nanofibers are treated at 450 °C in H2 and comparison samples annealed at 800 °C in N2 . The heat treatments are designed to achieve good crystallinity and desired mesoporous microstructure, resulting in enhanced electrochemical performance. The small amount of oxygen in the nanofibers annealed in H2 contributes to obtaining a lower internal resistance, and thus, improving the conductivity. The results show that the nanofibers obtained at 450 °C in H2 deliver an extraordinary capacity of 1022 mA h g(-1) and improved cyclic stability, with only 2.3 % capacity loss after 165 cycles at a current density of 100 mA g(-1) , as well as an outstanding rate capability. The greatly improved kinetics and cycling stability of the mesoporous MoS2 @C nanofibers can be attributed to the crosslinked conductive carbon nanofibers, the large specific surface area, the good crystallinity of MoS2 , and the robust mesoporous microstructure. The resulting nanofiber electrodes, with short mass- and charge-transport pathways, improved electrical conductivity, and large contact area exposed to electrolyte, permitting fast diffusional flux of Li ions, explains the improved kinetics of the interfacial charge-transfer reaction and the diffusivity of the MoS2 @C mesoporous nanofibers. It is believed that the integration of MoS2 nanocrystals and mesoporous carbon nanofibers may have a synergistic effect, giving a promising anode, and widening the applicability range into high performance and mass production in the Li-ion battery market. PMID:26515375

  8. 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.

  9. Mesoporous graphene-like nanobowls as Pt electrocatalyst support for highly active and stable methanol oxidation

    NASA Astrophysics Data System (ADS)

    Yan, Zaoxue; He, Guoqiang; Jiang, Zhifeng; Wei, Wei; Gao, Lina; Xie, Jimin

    2015-06-01

    Mesoporous graphene-like nanobowls (GLBs) with high surface area of 1091 m2 g-1, high pore volume of 2.7 cm3 g-1 and average pore diameter of 9.8 nm are synthesized through template method. The GLBs with inherent excellent electrical conductivity and chemical inertia show the properties of well mass transfer, poison resistance and stable loading of smaller Pt particles. Therefore, the Pt/GLB catalyst shows much higher activity and stability than that of commercial Pt/C (TKK) for methanol oxidation reaction (MOR). Therein, the peak current density on Pt/GLB (2075 mA mgPt-1) for MOR is 2.87 times that of commercial Pt/C (723 mA mgPt-1); and the onset potential for the MOR on the former is negatively shifted about 160 mV compared with that on the latter. The catalytic performances of the Pt/GLB are also better than those of the Pt loading on mesoporous amorphous carbon nanobowls (Pt/BLC), indicating promotion effect of graphite on Pt catalytic performance.

  10. Advanced hybrid supercapacitor based on a mesoporous niobium pentoxide/carbon as high-performance anode.

    PubMed

    Lim, Eunho; Kim, Haegyeom; Jo, Changshin; Chun, Jinyoung; Ku, Kyojin; Kim, Seongseop; Lee, Hyung Ik; Nam, In-Sik; Yoon, Songhun; Kang, Kisuk; Lee, Jinwoo

    2014-09-23

    Recently, hybrid supercapacitors (HSCs), which combine the use of battery and supercapacitor, have been extensively studied in order to satisfy increasing demands for large energy density and high power capability in energy-storage devices. For this purpose, the requirement for anode materials that provide enhanced charge storage sites (high capacity) and accommodate fast charge transport (high rate capability) has increased. Herein, therefore, a preparation of nanocomposite as anode material is presented and an advanced HSC using it is thoroughly analyzed. The HSC comprises a mesoporous Nb2O5/carbon (m-Nb2O5-C) nanocomposite anode synthesized by a simple one-pot method using a block copolymer assisted self-assembly and commercial activated carbon (MSP-20) cathode under organic electrolyte. The m-Nb2O5-C anode provides high specific capacity with outstanding rate performance and cyclability, mainly stemming from its enhanced pseudocapacitive behavior through introduction of a carbon-coated mesostructure within a voltage range from 3.0 to 1.1 V (vs Li/Li(+)). The HSC using the m-Nb2O5-C anode and MSP-20 cathode exhibits excellent energy and power densities (74 W h kg(-1) and 18,510 W kg(-1)), with advanced cycle life (capacity retention: ∼90% at 1000 mA g(-1) after 1000 cycles) within potential range from 1.0 to 3.5 V. In particular, we note that the highest power density (18,510 W kg(-1)) of HSC is achieved at 15 W h kg(-1), which is the highest level among similar HSC systems previously reported. With further study, the HSCs developed in this work could be a next-generation energy-storage device, bridging the performance gap between conventional batteries and supercapacitors. PMID:25137384

  11. Unidirectional self-assembly of soft templated mesoporous carbons by zone annealing

    NASA Astrophysics Data System (ADS)

    Xue, Jiachen; Singh, Gurpreet; Qiang, Zhe; Karim, Alamgir; Vogt, Bryan D.

    2013-08-01

    Surfactant or block copolymer-templated mesoporous films have been extensively explored, but achieving mesostructure coherence and unidirectional orientation over macroscopic dimensions has remained quite challenging for these self-assembled systems. Here, we extend the concepts associated with zone refinement of crystalline materials to soft templated mesoporous carbon films based on the cooperative assembly of commercial non-ionic surfactants (block copolymers) and phenolic resin oligomers (resol) to provide macroscopic alignment of both cubic (FDU-16) and hexagonal (FDU-15) mesostructures. The average orientation of these mesophases is determined from rotation grazing incidence small angle X-ray scattering (GISAXS) measurements. For FDU-15 templated by Pluronic P123, the orientation factor for the zone-annealed film is 0.98 based on the average of the second Legendre polynomial, but this orientation deteriorates significantly during carbonization. Notably, a thermal stabilization step following zone annealing preserves the orientation of the mesostructure during carbonization. The orientation factor for an isotropic cubic structure (FDU-16 templated by Pluronic F127) is only 0.48 (based on the 111 reflection with incident angle 0.15°) for the same zone annealing protocol, but this illustrates the versatility of zone annealing to different mesostructures. Unexpectedly, zone annealing of FDU-15 templated by Pluronic F127 leads to stabilization of the mesostructure through carbonization, whereas this structure collapses fully during carbonization even after extended oven annealing; despite no clear macroscopic orientation of the cylindrical mesostructure from zone annealing. Thermal zone annealing provides a simple methodology to produce highly ordered and macroscopically oriented stable mesoporous carbon films, but the efficacy is strongly tied to the mobility of the template during the zone annealing.Surfactant or block copolymer-templated mesoporous films have been extensively explored, but achieving mesostructure coherence and unidirectional orientation over macroscopic dimensions has remained quite challenging for these self-assembled systems. Here, we extend the concepts associated with zone refinement of crystalline materials to soft templated mesoporous carbon films based on the cooperative assembly of commercial non-ionic surfactants (block copolymers) and phenolic resin oligomers (resol) to provide macroscopic alignment of both cubic (FDU-16) and hexagonal (FDU-15) mesostructures. The average orientation of these mesophases is determined from rotation grazing incidence small angle X-ray scattering (GISAXS) measurements. For FDU-15 templated by Pluronic P123, the orientation factor for the zone-annealed film is 0.98 based on the average of the second Legendre polynomial, but this orientation deteriorates significantly during carbonization. Notably, a thermal stabilization step following zone annealing preserves the orientation of the mesostructure during carbonization. The orientation factor for an isotropic cubic structure (FDU-16 templated by Pluronic F127) is only 0.48 (based on the 111 reflection with incident angle 0.15°) for the same zone annealing protocol, but this illustrates the versatility of zone annealing to different mesostructures. Unexpectedly, zone annealing of FDU-15 templated by Pluronic F127 leads to stabilization of the mesostructure through carbonization, whereas this structure collapses fully during carbonization even after extended oven annealing; despite no clear macroscopic orientation of the cylindrical mesostructure from zone annealing. Thermal zone annealing provides a simple methodology to produce highly ordered and macroscopically oriented stable mesoporous carbon films, but the efficacy is strongly tied to the mobility of the template during the zone annealing. Electronic supplementary information (ESI) available: GISAXS profiles for the FDU-15-F127 at φ = 0° and φ = 90° is included along with 2D GISAXS data for all azimuthal data associated with FDU-15-P123 to illustrate the azimuthal dependence on the diffraction patterns. See DOI: 10.1039/c3nr02821f

  12. Progammed synthesis of magnetic mesoporous silica coated carbon nanotubes for organic pollutant adsorption

    NASA Astrophysics Data System (ADS)

    Tong, Yue; Zhang, Min; Xia, Peixiong; Wang, Linlin; Zheng, Jing; Li, Weizhen; Xu, Jingli

    2016-05-01

    Magnetic mesoporous silica coated carbon nanotubes were produced from hydrophilic monodisperse magnetic nanoparticles decorated carbon nanotubes using well controlled programmed synthesis method and were characterized by TEM, XRD, FTIR, TGA, N2 adsorption-desorption and VSM. The well-designed mesoporous magnetic nanotubes had a large specific area, a highly open mesoporous structure and high magnetization. Firstly, SiO2-coated maghemite/CNTs nanoparticles (CNTs/Fe3O4@SiO2 composites) were synthesized by the combination of high temperature decomposition process and an sol-gel method, in which the iron acetylacetonate as well as TEOS acted as the precursor for maghemite and SiO2, respectively. The CNTs/Fe3O4@SiO2 composites revealed a core-shell structure, Then, CNTs/Fe3O4@mSiO2 was obtained by extracting cetyltrimethylammonium bromide (CTAB) via an ion-exchange procedure. The resulting composites show not only a magnetic response to an externally applied magnetic field, but also can be a good adsorbent for the organic pollutant in the ambient temperature.

  13. The electrochemical performance of ordered mesoporous carbon/nickel compounds composite material for supercapacitor

    SciTech Connect

    Feng, Jicheng; Zhao, Jiachang; Tang, Bohejin; Liu, Ping; Xu, Jingli

    2010-12-15

    A series of high performance ordered mesoporous carbon/nickel compounds composites have been synthesized by a combination of incipient wetness impregnation and hydrothermal method for the first time. X-ray diffraction (XRD), N{sub 2} adsorption/desorption isotherms and transmission electron microscopy (TEM) are used to characterize the composites derived at the hydrothermal temperature of 125, 150, 175, 200, 250, 275 and 300 {sup o}C. The formation of nanosized nickel compounds, fully inside the mesopore system, was confirmed with XRD and TEM. An N{sub 2} adsorption/desorption isotherms measurements still revealed mesoporosity for the host/guest compounds. It is noteworthy that an OMC/nickel nitrate hydroxide hydrate composite (OMCN-150) exhibits more excellent performance. Based on the various hydrothermal temperatures of the composite, the capacitance of an OMCN-150 delivering the best electrochemical performance is about 2.4 (5 mV s{sup -1}) and 1.5 (50 mV s{sup -1}) times of the pristine OMC. The capacitance retention of an OMCN-150 is 96.1%, which indicates that the electrochemical performance of the supercapacitor is improved greatly, and represents novel research and significant advances in the field of electrode composite materials for supercapacitor. -- Graphical abstract: A series of high performance nickel compound/ordered mesoporous carbon composites were synthesized by a combination of incipient wetness impregnation and hydrothermal method for the first time. Display Omitted

  14. PtRu nanoparticles supported on nitrogen-doped polyhedral mesoporous carbons as electrocatalyst for methanol oxidation

    NASA Astrophysics Data System (ADS)

    Zhang, Yunsong; Zhu, Rong; Cui, Ying; Zhong, Jindi; Zhang, Xiaohua; Chen, Jinhua

    2014-04-01

    Nitrogen-doped mesoporous carbons (NMPCs) with well-developed polyhedral morphology were prepared by direct carbonization of zeolitic imidazolate framework-8 (ZIF-8) nanopolyhedrons. The fantastic structural characteristics of NMPCs such as ultrahigh BET surface area (1960 m2 g-1), large pore volume (1.16 cm3 g-1), and nitrogen doping make it an excellent catalyst support. PtRu nanoparticles (with a size of approximately 1.9 nm) were homogeneously supported on NMPCs by microwave-assisted reduction in ethylene glycol, and the obtained PtRu/NMPCs catalyst shows a significantly higher electrocatalytic activity and stability for methanol oxidation than the typical commercial PtRu/C (E-TEK) catalyst.

  15. PtRu nanoparticles supported on nitrogen-doped polyhedral mesoporous carbons as electrocatalyst for methanol oxidation.

    PubMed

    Zhang, Yunsong; Zhu, Rong; Cui, Ying; Zhong, Jindi; Zhang, Xiaohua; Chen, Jinhua

    2014-04-01

    Nitrogen-doped mesoporous carbons (NMPCs) with well-developed polyhedral morphology were prepared by direct carbonization of zeolitic imidazolate framework-8 (ZIF-8) nanopolyhedrons. The fantastic structural characteristics of NMPCs such as ultrahigh BET surface area (1960 m(2) g(-1)), large pore volume (1.16 cm(3) g(-1)), and nitrogen doping make it an excellent catalyst support. PtRu nanoparticles (with a size of approximately 1.9 nm) were homogeneously supported on NMPCs by microwave-assisted reduction in ethylene glycol, and the obtained PtRu/NMPCs catalyst shows a significantly higher electrocatalytic activity and stability for methanol oxidation than the typical commercial PtRu/C (E-TEK) catalyst. PMID:24594620

  16. A direct and quantitative three-dimensional reconstruction of the internal structure of disordered mesoporous carbon with tailored pore size.

    PubMed

    Balach, Juan; Soldera, Flavio; Acevedo, Diego F; Mücklich, Frank; Barbero, César A

    2013-06-01

    A new technique that allows direct three-dimensional (3D) investigations of mesopores in carbon materials and quantitative characterization of their physical properties is reported. Focused ion beam nanotomography (FIB-nt) is performed by a serial sectioning procedure with a dual beam FIB-scanning electron microscopy instrument. Mesoporous carbons (MPCs) with tailored mesopore size are produced by carbonization of resorcinol-formaldehyde gels in the presence of a cationic surfactant as a pore stabilizer. A visual 3D morphology representation of disordered porous carbon is shown. Pore size distribution of MPCs is determined by the FIB-nt technique and nitrogen sorption isotherm methods to compare both results. The obtained MPCs exhibit pore sizes of 4.7, 7.2, and 18.3 nm, and a specific surface area of ca. 560 m(2)/g. PMID:23534911

  17. Reduction of Plutonium in Acidic Solutions by Mesoporous Carbons

    DOE PAGESBeta

    Parsons-Moss, Tashi; Jones, Stephen; Wang, Jinxiu; Wu, Zhangxiong; Uribe, Eva; Zhao, Dongyuan; Nitsche, Heino

    2015-12-19

    Batch contact experiments with several porous carbon materials showed that carbon solids spontaneously reduce the oxidation state of plutonium in 1-1.5 M acid solutions, without significant adsorption. The final oxidation state and rate of Pu reduction varies with the solution matrix, and also depends on the surface chemistry and surface area of the carbon. It was demonstrated that acidic Pu(VI) solutions can be reduced to Pu(III) by passing through a column of porous carbon particles, offering an easy alternative to electrolysis with a potentiostat.

  18. Electrografting of 3-Aminopropyltriethoxysilane on a Glassy Carbon Electrode for the Improved Adhesion of Vertically Oriented Mesoporous Silica Thin Films.

    PubMed

    Nasir, Tauqir; Zhang, Lin; Vilà, Neus; Herzog, Grégoire; Walcarius, Alain

    2016-05-01

    Vertically oriented mesoporous silica has proven to be of interest for applications in a variety of fields (e.g., electroanalysis, energy, and nanotechnology). Although glassy carbon is widely used as an electrode material, the adherence of silica deposits is rather poor, causing mechanical instability. A solution to improve the adhesion of mesoporous silica films onto glassy carbon electrodes without compromising the vertical orientation and the order of the mesopores will greatly contribute to the use of this kind of modified carbon electrode. We propose here the electrografting of 3-aminopropyltriethoxysilane on glassy carbon as a molecular glue to improve the mechanical stability of the silica film on the electrode surface without disturbing the vertical orientation and the order of the mesoporous silica obtained by electrochemically assisted self-assembly. These findings are supported by a series of surface chemistry techniques such as X-ray photoelectron spectroscopy, scanning and transmission electron microscopy, and cyclic voltammetry. Finally, methylviologen was used as a model redox probe to investigate the cathodic potential region of both glassy carbon and indium tin oxide electrodes modified with mesoporous silica in order to demonstrate further the interest in the approach developed here. PMID:27065214

  19. Mesoporous carbon encapsulated with SrO nanoparticles for the transesterification of ethyl acetoacetate.

    PubMed

    Raja, Pradeep Kumar; Chokkalingam, Anand; Priya, Subramaniam V; Abdul Wahab, Mohammad; Dhawale, Dattatray S; Lawrence, Geoffrey; Ariga, Katsuhiko; Jayavel, Ramasamy; Vinu, Ajayan

    2012-11-01

    Highly basic active sites were introduced by the encapsulation of SrO nanoparticles inside the porous channels of highly ordered mesoporous carbon using wet-impregnation method. The samples prepared were thoroughly investigated employing various physico-chemical characterization techniques such as X-ray diffraction (XRD), N2 adsorption, high resolution transmission electron microscope (HRTEM) and elemental mapping. The basic sites located inside the nanochannels were quantified by the temperature programmed desorption (TPD) of CO2. XRD, N2 adsorption and HRTEM results revealed that the structural order of the parent CMK-3 support is retained even after higher loading of SrO nanoparticles. TPD of CO2 profiles confirmed that the number of basic active sites can be controlled by varying the SrO loading and the pore diameter of the CMK-3 support. The catalytic potential of the prepared samples was investigated on the transesterification of ethyl acetoacetate (EAA) as a probe reaction. Among the catalysts studied, CMK-3-150 loaded with 30 wt% of SrO nanoparticles exhibited the highest catalytic activity. The effect of various alcohols such as aryl (benzyl alcohol), aliphatic (1-butanol and 1-octanol) and cyclic alcohols (cyclohexanol and furfuryl alcohol) affecting the activity of the catalyst was also investigated. It was found that the catalyst offers maximum conversion when linear aliphatic alcohols especially, 1-butanol with shorter chain length are used. The amount of SrO loading, pore diameter of the CMK-3 support and the weight of the catalyst affecting the catalytic performance of the samples were investigated and discussed in accordance with the physico-chemical characterization data of the catalysts. PMID:23421232

  20. Mesoporous and carbon hybrid structures from layered molecular precursors for Li-ion battery application: the case of β-In2S3.

    PubMed

    Zhang, Ming-Jian; Tian, Lei-Lei; Li, Shuankui; Lin, Ling-Piao; Pan, Feng

    2016-04-01

    A new method was demonstrated to construct mesoporous and carbon hybrid structures of β-In2S3 from the thermal decomposition of layered molecular precursors. When applied to LIBs, they all exhibit good cycling stability and excellent rate performance due to the great uniformity of mesopores and pyrolysis carbon distributed in the materials. PMID:26957349

  1. Palladium on Nitrogen-Doped Mesoporous Carbon: A Bifunctional Catalyst for Formate-Based, Carbon-Neutral Hydrogen Storage.

    PubMed

    Wang, Fanan; Xu, Jinming; Shao, Xianzhao; Su, Xiong; Huang, Yanqiang; Zhang, Tao

    2016-02-01

    The lack of safe, efficient, and economical hydrogen storage technologies is a hindrance to the realization of the hydrogen economy. Reported herein is a reversible formate-based carbon-neutral hydrogen storage system that is established over a novel catalyst comprising palladium nanoparticles supported on nitrogen-doped mesoporous carbon. The support was fabricated by a hard template method and nitridated under a flow of ammonia. Detailed analyses demonstrate that this bicarbonate/formate redox equilibrium is promoted by the cooperative role of the doped nitrogen functionalities and the well-dispersed, electron-enriched palladium nanoparticles. PMID:26763714

  2. Microporous and mesoporous carbide-derived carbons for strain modification of electromechanical actuators.

    PubMed

    Torop, Janno; Arulepp, Mati; Sugino, Takushi; Asaka, Kinji; Jänes, Alar; Lust, Enn; Aabloo, Alvo

    2014-03-18

    Low-voltage stimuli-responsive actuators based on carbide-derived carbon (CDC) porous structures were demonstrated. Bending actuators showed a differential electromechanical response defined by the porosity of the CDC used in the electrode layer. Highly porous CDCs prepared from TiC (mainly microporous), B4C (micromesoporous), and Mo2C (mainly mesoporous) precursors were selected to demonstrate the influence of porosity parameters on the electromechanical performance of actuators. CDC-based bending-type actuators showed a porosity-driven displacement response over a frequency range of 200 to 0.005 Hz at an applied excitation voltage of ±2 V. The displacement response of the CDC actuators increased with an increasing number of mesopores in the electrode layer, and the generated strain of the bending actuators was proportional to the total porosity (micropores and mesopores) of the CDC. The modifiable electromechanical response that arises from the precise porosity control attained through tailoring the CDC architecture demonstrates that these actuators hold great promise for smart, low-voltage-driven actuation devices. PMID:24580143

  3. Highly ordered magnetic mesoporous silicas for effective elimination of carbon monoxide

    SciTech Connect

    Lee, Jiho; Ho Chang, Jeong

    2012-04-15

    Catalysts based on crystalline nanoparticles of Fe metal supported on mesoporous silica have been developed. The synthetic process involves hydrogen reduction processing for high abundant Fe metal nanoparticles within the mesopores, in which impregnated Fe salt in the inner nanopores of mesoporous silica is thermally treated under hydrogen at 500 Degree-Sign C. Detailed characterization was achieved by XRD, XPS, BET, and HR-TEM techniques. The catalytic efficiency was demonstrated as a function of the used amounts and reaction time. The results show that more than 90% of the carbon monoxide was eliminated at room temperature during a period 80 min with 0.5 g of catalyst. - Graphical abstract: Strategy for the preparation of highly abundant Fe nanoparticle embedded MS catalyst by hydrogen reduction process and HR-TEM images of cross-sectional and top view. Highlights: Black-Right-Pointing-Pointer MS based heterogeneous catalyst with Fe nanoparticles were demonstrated for CO elimination. Black-Right-Pointing-Pointer Highly Fe nanoparticle embedded MS catalyst prepared by hydrogen reduction process. Black-Right-Pointing-Pointer Systematic characterization was achieved by XRD, XPS, BET, and HR-TEM analyses. Black-Right-Pointing-Pointer More than 90% of the CO was eliminated at RT during 80 min with 0.5 g of catalyst.

  4. Highly Hydrophilic Luminescent Magnetic Mesoporous Carbon Nanospheres for Controlled Release of Anticancer Drug and Multimodal Imaging.

    PubMed

    Mohapatra, Sasmita; Rout, Smruti R; Das, Rahul K; Nayak, Santoshi; Ghosh, Sudip K

    2016-02-16

    Judicious combination of fluorescence and magnetic properties along with ample drug loading capacity and control release property remains a key challenge in the design of nanotheranostic agents. This paper reports the synthesis of highly hydrophilic optically traceable mesoporous carbon nanospheres which can sustain payloads of the anticancer drug doxorubicin and T2 contrast agent such as cobalt ferrite nanoparticles. The luminescent magnetic hybrid system has been prepared on a mesoporous silica template using a resorcinol-formaldehyde precursor. The mesoporous matrix shows controlled release of the aromatic drug doxorubicin due to disruption of supramolecular π-π interaction at acidic pH. The particles show MR contrast behavior by affecting the proton relaxation with transverse relaxivity (r2) 380 mM(-1) S(-1). The multicolored emission and upconversion luminescence property of our sample are advantageous in bioimaging. In vitro cell experiments shows that the hybrid nanoparticles are endocyted by the tumor cells through passive targeting. The pH-responsive release of doxorubicin presents chemotherapeutic inhibition of cell growth through induction of apoptosis. PMID:26794061

  5. Waste-Glycerol-Directed Synthesis of Mesoporous Silica and Carbon with Superior Performance in Room-Temperature Hydrogen Production from Formic Acid

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Wook; Jin, Min-Ho; Park, Ji Chan; Lee, Chun-Boo; Oh, Duckkyu; Lee, Sung-Wook; Park, Jin-Woo; Park, Jong-Soo

    2015-10-01

    The development of easier, cheaper, and more ecofriendly synthetic methods for mesoporous materials remains a challenging topic to commercialize them, and the transformation of waste glycerol, as a biodiesel byproduct, into something useful and salable is one of the pending issues to be resolved. Here we first report that mesoporous silica (KIE-6) and carbon (KIE-7) can be simultaneously synthesized by using cheap and ecofriendly crude-waste-glycerol of biodiesel with or without glycerol purification, and we demonstrated the excellent performance of the mesoporous material as a catalyst support for formic acid decomposition. As a result, Pd-MnOx catalysts supported on NH2-functionalized KIE-6 showed the highest catalytic activity (TOF: 540.6 h-1) ever reported for room-temperature formic acid decomposition without additives. Moreover, we conducted life-cycle assessment (LCA) from biomass cultivation through biodiesel production to KIE-6 and KIE-7 preparation, and it was confirmed that CO2 emission during synthesis of KIE-6 and KIE-7 could be reduced by 87.1% and 85.7%, respectively. We believe that our study suggested more ecofriendly and industry-friendly approaches for preparation of mesoporous materials, and utilization of waste glycerol.

  6. Waste-Glycerol-Directed Synthesis of Mesoporous Silica and Carbon with Superior Performance in Room-Temperature Hydrogen Production from Formic Acid.

    PubMed

    Lee, Dong-Wook; Jin, Min-Ho; Park, Ji Chan; Lee, Chun-Boo; Oh, Duckkyu; Lee, Sung-Wook; Park, Jin-Woo; Park, Jong-Soo

    2015-01-01

    The development of easier, cheaper, and more ecofriendly synthetic methods for mesoporous materials remains a challenging topic to commercialize them, and the transformation of waste glycerol, as a biodiesel byproduct, into something useful and salable is one of the pending issues to be resolved. Here we first report that mesoporous silica (KIE-6) and carbon (KIE-7) can be simultaneously synthesized by using cheap and ecofriendly crude-waste-glycerol of biodiesel with or without glycerol purification, and we demonstrated the excellent performance of the mesoporous material as a catalyst support for formic acid decomposition. As a result, Pd-MnOx catalysts supported on NH2-functionalized KIE-6 showed the highest catalytic activity (TOF: 540.6 h(-1)) ever reported for room-temperature formic acid decomposition without additives. Moreover, we conducted life-cycle assessment (LCA) from biomass cultivation through biodiesel production to KIE-6 and KIE-7 preparation, and it was confirmed that CO2 emission during synthesis of KIE-6 and KIE-7 could be reduced by 87.1% and 85.7%, respectively. We believe that our study suggested more ecofriendly and industry-friendly approaches for preparation of mesoporous materials, and utilization of waste glycerol. PMID:26515193

  7. Waste-Glycerol-Directed Synthesis of Mesoporous Silica and Carbon with Superior Performance in Room-Temperature Hydrogen Production from Formic Acid

    PubMed Central

    Lee, Dong-Wook; Jin, Min-Ho; Park, Ji Chan; Lee, Chun-Boo; Oh, Duckkyu; Lee, Sung-Wook; Park, Jin-Woo; Park, Jong-Soo

    2015-01-01

    The development of easier, cheaper, and more ecofriendly synthetic methods for mesoporous materials remains a challenging topic to commercialize them, and the transformation of waste glycerol, as a biodiesel byproduct, into something useful and salable is one of the pending issues to be resolved. Here we first report that mesoporous silica (KIE-6) and carbon (KIE-7) can be simultaneously synthesized by using cheap and ecofriendly crude-waste-glycerol of biodiesel with or without glycerol purification, and we demonstrated the excellent performance of the mesoporous material as a catalyst support for formic acid decomposition. As a result, Pd-MnOx catalysts supported on NH2-functionalized KIE-6 showed the highest catalytic activity (TOF: 540.6 h−1) ever reported for room-temperature formic acid decomposition without additives. Moreover, we conducted life-cycle assessment (LCA) from biomass cultivation through biodiesel production to KIE-6 and KIE-7 preparation, and it was confirmed that CO2 emission during synthesis of KIE-6 and KIE-7 could be reduced by 87.1% and 85.7%, respectively. We believe that our study suggested more ecofriendly and industry-friendly approaches for preparation of mesoporous materials, and utilization of waste glycerol. PMID:26515193

  8. Carbon nanofiber mesoporous films: efficient platforms for bio-hydrogen oxidation in biofuel cells.

    PubMed

    de Poulpiquet, Anne; Marques-Knopf, Helena; Wernert, Véronique; Giudici-Orticoni, Marie Thérèse; Gadiou, Roger; Lojou, Elisabeth

    2014-01-28

    The discovery of oxygen and carbon monoxide tolerant [NiFe] hydrogenases was the first necessary step toward the definition of a novel generation of hydrogen fed biofuel cells. The next important milestone is now to identify and overcome bottlenecks limiting the current densities, hence the power densities. In the present work we report for the first time a comprehensive study of herringbone carbon nanofiber mesoporous films as platforms for enhanced biooxidation of hydrogen. The 3D network allows mediatorless hydrogen oxidation by the membrane-bound hydrogenase from the hyperthermophilic bacterium Aquifex aeolicus. We investigate the key physico-chemical parameters that enhance the catalytic efficiency, including surface chemistry and hierarchical porosity of the biohybrid film. We also emphasize that the catalytic current is limited by mass transport inside the mesoporous carbon nanofiber film. Provided hydrogen is supplied inside the carbon film, the combination of the hierarchical porosity of the carbon nanofiber film with the hydrophobicity of the treated carbon material results in very high efficiency of the bioelectrode. By optimization of the whole procedure, current densities as high as 4.5 mA cm(-2) are reached with a turnover frequency of 48 s(-1). This current density is almost 100 times higher than when hydrogenase is simply adsorbed at a bare graphite electrode, and more than 5 times higher than the average of the previous reported current densities at carbon nanotube modified electrodes, suggesting that carbon nanofibers can be efficiently used in future sustainable H2/O2 biofuel cells. PMID:24296569

  9. Spherical nitrogen-doped hollow mesoporous carbon as an efficient bifunctional electrocatalyst for Zn-air batteries

    NASA Astrophysics Data System (ADS)

    Hadidi, Lida; Davari, Elaheh; Iqbal, Muhammad; Purkait, Tapas K.; Ivey, Douglas G.; Veinot, Jonathan G. C.

    2015-12-01

    Materials based upon porous carbon have gained considerable attention due to their high surface area, electric conductivity, thermal and chemical stability, low density, and availability. These superior properties make them ideal for diverse applications. Doping these carbon nanostructures holds promise of designing the properties of these structures and opening the door to practical applications. Herein, we report the preparation of hollow N-doped mesoporous carbon (HMC) spheres fabricated via polymerization and carbonization of dopamine on a sacrificial spherical SiO2 template that is removed upon hydrofluoric acid etching. The morphology and structural features of these HMCs were evaluated using scanning electron microscopy and transmission electron microscopy and the N-doping (7.1 at%) was confirmed by X-ray photoelectron spectroscopy (XPS). The oxygen reduction/evolution reaction (ORR/OER) performance of N-doped HMC was evaluated using rotating disk electrode (RDE) voltammetry in an alkaline electrolyte. N-doped HMC demonstrated a high ORR onset potential of -0.055 V (vs. Hg/HgO) and excellent stability. The outstanding bifunctional activity was implemented in a practical Zn-air battery (ZAB), which exhibited a small charge-discharge voltage polarization of 0.89 V and high stability over repeated cycling.Materials based upon porous carbon have gained considerable attention due to their high surface area, electric conductivity, thermal and chemical stability, low density, and availability. These superior properties make them ideal for diverse applications. Doping these carbon nanostructures holds promise of designing the properties of these structures and opening the door to practical applications. Herein, we report the preparation of hollow N-doped mesoporous carbon (HMC) spheres fabricated via polymerization and carbonization of dopamine on a sacrificial spherical SiO2 template that is removed upon hydrofluoric acid etching. The morphology and structural features of these HMCs were evaluated using scanning electron microscopy and transmission electron microscopy and the N-doping (7.1 at%) was confirmed by X-ray photoelectron spectroscopy (XPS). The oxygen reduction/evolution reaction (ORR/OER) performance of N-doped HMC was evaluated using rotating disk electrode (RDE) voltammetry in an alkaline electrolyte. N-doped HMC demonstrated a high ORR onset potential of -0.055 V (vs. Hg/HgO) and excellent stability. The outstanding bifunctional activity was implemented in a practical Zn-air battery (ZAB), which exhibited a small charge-discharge voltage polarization of 0.89 V and high stability over repeated cycling. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06028a

  10. A covalent route for efficient surface modification of ordered mesoporous carbon as high performance microwave absorbers.

    PubMed

    Zhou, Hu; Wang, Jiacheng; Zhuang, Jiandong; Liu, Qian

    2013-12-21

    A covalent route has been successfully utilized for the surface modification of ordered mesoporous carbon (OMC) CMK-3 by in situ polymerization and grafting of methyl methacrylate (MMA) in the absence of any solvent. The modified CMK-3 carbon particles have a high loading of 19 wt% poly(methyl methacrylate) (PMMA), named PMMA-g-CMK-3, and also maintain their high surface area and mesoporous structure. The in situ polymerization technique endows a significantly enhanced electric conductivity (0.437 S m(-1)) of the resulting PMMA-g-CMK-3/PMMA composite, about two orders of magnitude higher than 1.34 × 10(-3) S m(-1) of PMMA/CMK-3 obtained by the solvent mixing method. A minimum reflection loss (RL) value of -27 dB and a broader absorption band (over 3 GHz) with RL values <-10 dB are obtained for the in situ polymerized PMMA-g-CMK-3/PMMA in a frequency range of 8.2-12.4 GHz (X-band), implying its great potential as a microwave absorbing material. The maximum absorbance efficiency for the in situ polymerized sample increases remarkably compared to that (-10 dB) of CMK-3/PMMA prepared by the solvent mixing method. Changing the thickness of the absorber can efficiently adjust the frequency corresponding to the best microwave absorbance ability. The enhanced microwave absorption by the surface modified CMK-3 is ascribed to high dielectric loss. This in situ polymerization for the surface modification of mesoporous carbons opens up a new method and idea for developing light-weight and high-performance microwave absorbing materials. PMID:24170288

  11. Preparation and drug release behavior of temperature-responsive mesoporous carbons

    NASA Astrophysics Data System (ADS)

    Wang, Xiufang; Liu, Ping; Tian, Yong

    2011-06-01

    A temperature-responsive composite based on poly (N-isopropylacrylamide) (PNIPAAm) and ordered mesoporous carbons (OMCs) has been successfully prepared by a simple wetness impregnation technique. The structures and properties of the composite were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), N 2 sorption, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The results showed that the inclusion of PNIPAAm had not greatly changed the basic ordered pore structure of the OMCs. Ibuprofen (IBU) was selected as model drug, and in vitro test of IBU release exhibited a temperature-responsive controlled release delivery.

  12. Cubic and hexagonal mesoporous carbon in the pores of anodic alumina membranes.

    PubMed

    Schuster, Jörg; Keilbach, Andreas; Köhn, Ralf; Döblinger, Markus; Dörfler, Thilo; Dennenwaldt, Teresa; Bein, Thomas

    2011-08-16

    Cubic and circular hexagonal mesoporous carbon phases in the confined environment of the pores of anodic alumina membranes (AAM) were obtained by organic-organic self-assembly of a preformed oligomeric resol precursor and the triblock copolymer templates Pluronic F127 or P123, respectively. Casting and solvent evaporation were followed by self-assembly and the formation of a condensed wall material by thermopolymerization of the precursor oligomers, thus resulting in mesostructured phenolic resin phases. Subsequent thermal decomposition of the surfactant and carbonization were achieved through thermal treatment at temperatures up to 1000 °C under an inert atmosphere. The resulting hierarchical mesoporous composite materials were characterized by small-angle X-ray scattering and nitrogen-sorption measurements. The structural features were directly imaged in TEM cross-sections of the composite membranes. For both structures, the AAM pores were completely filled and no shrinkage was observed due to strong adhesion of the carbon-wall material to the AAM pore walls. As a consequence, the pore size of the mesophase system stays almost constant even after thermal treatment at 1000 °C. PMID:21732429

  13. Nitrogen-doped mesoporous carbon for energy storage in vanadium redox flow batteries

    SciTech Connect

    Dai, Sheng; Shao, Yuyan; Wang, Xiqing; Engelhard, Mark H; Wang, Congmin; Liu, Jun; YANG, ZHENGUO; Lin, Yuehe

    2010-01-01

    We demonstrate an excellent performance of nitrogen-doped mesoporous carbon (N-MPC) for energy storage in vanadium redox flow batteries. Mesoporous carbon (MPC) is prepared using a soft-template method and doped with nitrogen by heat-treating MPC in NH{sub 3}. N-MPC is characterized with X-ray photoelectron spectroscopy and transmission electron microscopy. The redox reaction of [VO]{sup 2+}/[VO{sub 2}]{sup +} is characterized with cyclic voltammetry and electrochemical impedance spectroscopy. The electrocatalytic kinetics of the redox couple [VO]{sup 2+}/[VO{sub 2}]{sup +} is significantly enhanced on N-MPC electrode compared with MPC and graphite electrodes. The reversibility of the redox couple [VO]{sup 2+}/[VO{sub 2}]{sup +} is greatly improved on N-MPC (0.61 for N-MPC vs. 0.34 for graphite), which is expected to increase the energystorage efficiency of redoxflowbatteries. Nitrogen doping facilitates the electron transfer on electrode/electrolyte interface for both oxidation and reduction processes. N-MPC is a promising material for redoxflowbatteries. This also opens up new and wider applications of nitrogen-doped carbon.

  14. Additive-Driven Self-Assembly of Well Ordered Mesoporous Carbon/Iron Oxide Nanoparticle Composites for Supercapacitors

    NASA Astrophysics Data System (ADS)

    Lin, Ying; Wang, Xinyu; Qian, Gang; Watkins, James; Department of Polymer Science and Engineering, University of Massachusetts Amherst Team

    2014-03-01

    Supercapacitors have attracted significant attention as energy storage devices for applications to meet the requirements of fast charge and discharge, high power density, and long cycle life. Recent research efforts demonstrate that the metal oxide- mesoporous carbon nanocomposite materials are indeed a class of promising electrode materials for high performance supercapacitors. However several major drawbacks for metal oxide-carbon nanocomposite materials remain, such as relatively low loadings of the metal oxide, aggregation of nanoparticles, and the lack of an ordered mesoporous structure. Here we demonstrate that well ordered mesoporous carbon/iron oxide composites can be prepared through simple carbonization of blends of block copolymers serving as the source of carbon and a porogen, e.g., poly(t-butyl acrylate)-block-polyacrylonitrile (PtBA-b-PAN), and iron oxide nanoparticles (NPs). Strong interactions between phenol-functionalized iron oxide NPs and polyacrylonitrile result in a preferential dispersion of the nanoparticles within the PAN domains and leads to ordered nanostructured mesoporous carbon framework containing upto 30 wt This work was supported by the NSF Center for Hierarchical Manufacturing at the University of Massachusetts (CMMI-1025020).

  15. Graphitic Mesoporous Carbon as a Support of Promoted Rh Catalysts for Hydrogenation of Carbon Monoxide to Ethanol

    SciTech Connect

    Chai, Songhai; Howe, Jane Y; Wang, Xiqing; Kidder, Michelle; Schwartz, Viviane; Golden, Melissa L; Overbury, Steven {Steve} H; Dai, Sheng; Jiang, Deen

    2012-01-01

    Graphitic mesoporous carbon (GMC), prepared through high-temperature graphitization of soft-templated amorphous mesoporous carbon (AMC), was used as the support for Mn, Li, and Fe triple-promoted Rh catalysts for CO hydrogenation to ethanol. The use of GMC results in C{sub 2}H{sub 5}OH selectivity and formation rate comparable to nonporous SiO{sub 2} support along with a significant inhibition on the formation of undesired CH{sub 4} and light hydrocarbons at the expense of appreciable amounts of CO{sub 2} produced. The better catalytic performance of promoted-Rh/GMC than those supported on other carbon allotropes (AMC and non-porous graphitic carbon black) seems to be associated with the specific graphitic structure and mesoporosity of GMC. The surface modification of GMC by wet oxidation leads to considerable increases in C{sub 2}H{sub 5}OH selectivity and formation rate. The modified GMC as a support shows substantially greater CO{sub 2}-free selectivity for C{sub 2}H{sub 5}OH than the SiO{sub 2}.

  16. Gold and palladium adsorption from leached electronic scrap using ordered mesoporous carbon nanoscaffolds

    SciTech Connect

    McDowell, Rocklan; Dutech, Guy

    2014-09-01

    Ordered mesoporous carbon (OMC) nanoscaffolds are engineered agglomerates of carbon nanotubes held together by small carbon nanofibers with uniform pore sizes, high pore volume, and high channel permeability. These materials exhibit very high affinity for the adsorption of gold from aqueous acidic mixtures. The efficiency of gold recovery is comparable to those typically accomplished using biopolymer-based adsorbents. The adsorption efficiency for other precious metals such as palladium and platinum is lower. Studies on the precious metal (Au, Pd) adsorption on OMC materials from actual liquors of leached electronics will be presented. Adsorption properties will be compared for several different sorbents used for the recovery of precious metals. The leach liquor compositions for three different types of electronic scrap materials (personal computer board, cell phone and tv input/output board) will be presented. The sorption efficiencies for Au, Pd, together with a spectrum of competing and non-competing metals, from such leach mixtures will be compared.

  17. Fabrication of Nitrogen-Doped Mesoporous-Carbon-Coated Palladium Nanoparticles: An Intriguing Electrocatalyst for Methanol and Formic Acid Oxidation.

    PubMed

    Ray, Chaiti; Dutta, Soumen; Sahoo, Ramkrishna; Roy, Anindita; Negishi, Yuichi; Pal, Tarasankar

    2016-05-20

    Inspired by the attractive catalytic properties of palladium and the inert nature of carbon supports in catalysis, a concise and simple methodology for in situ nitrogen-doped mesoporous-carbon-supported palladium nanoparticles (Pd/N-C) has been developed by carbonizing a palladium dimethylglyoximate complex. The as-synthesized Pd/N-C has been exfoliated as a fuel cell catalyst by studying the electro-oxidation of methanol and formic acid. The material synthesized at 400 °C,namely, Pd/N-C-400,exhibitssuperior mass activity and stability among catalysts synthesized under different carbonization temperaturesbetween300 and 500 °C. The unique 1D porous structure in Pd/N-C-400 helps better electron transport at the electrode surface, which eventually leads to about five times better catalytic activity and about two times higher stability than that of commercial Pd/C. Thus, our designed sacrificial metal-organic templatedirected pathway becomes a promising technique for Pd/N-C synthesis with superior catalytic performances. PMID:27016895

  18. Magnetic motive, ordered mesoporous carbons with partially graphitized framework and controllable surface wettability: preparation, characterization and their selective adsorption of organic pollutants in water

    NASA Astrophysics Data System (ADS)

    Zhang, Bin; Liu, Chen; Kong, Weiping; Qi, Chenze

    2016-02-01

    Magnetically active, ordered and stable mesoporous carbons with partially graphitized networks and controllable surface wettability (PR-Fe-P123-800 and PR-Ni-P123-800) have been synthesized through direct carbonization of Fe or Ni functionalized, and ordered mesoporous polymers at 800°C, which could be synthesized from self assembly of resol (phenol/formaldehyde) with block copolymer template (P123) in presence of Fe3+ or Ni2+, and hydrothermal treatment at 200°C. PR-Fe-P123-800 and PR-Ni-P123-800 possess ordered and uniform mesopores, large BET surface areas, good stabilities, controllable surface wettability and partially graphitized framework. The above structural characteristics result in their enhanced selective adsorption property and good reusability for organic pollutants such as RhB, p-nitrophenol and n-heptane in water, which could be easily regenerated through separation under constant magnetic fields and washing with ethanol solvent. The unique magnetically active and adsorptive property found in PR-Fe-P123-800 and PR-Ni-P123-800 will be very important for them to be used as efficient absorbents for removal of various organic pollutants in water.

  19. Ordered mesoporous carbon/graphene nano-sheets composites as counter electrodes in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Shao, Leng-Leng; Chen, Ming; Ren, Tie-Zhen; Yuan, Zhong-Yong

    2015-01-01

    The composites of ordered mesoporous carbon (OMC) and graphene nano-sheets (GNS) are prepared by mixing OMC with different weight ratios of GNS, and utilized as counter electrode (CE) materials for dye-sensitized solar cells (DSSCs). Electrochemical impedance spectroscopy, Tafel polarization, and cyclic voltammetry measurements demonstrate that the OMC/GNS CEs display the enhanced electron transport property and fast reduction rate of I3- in comparison with those of the individual OMC and GNS CEs, due to the combination of superior electrical conductivity of GNS and good catalytic activity of OMC. Under AM 1.5 irradiation (100 mW cm-2), the DSSCs based on the OMC/GNS CEs show a maximum power conversion efficiency of 6.82%, which is comparable to 7.08% of the cell with the conventional Pt CE at the same experimental conditions, suggesting that the OMC/GNS composites are one of advanced CE materials for low-cost DSSCs.

  20. Mesoporous carbon adsorbents from melamine-formaldehyde resin using nanocasting technique for CO2 adsorption.

    PubMed

    Goel, Chitrakshi; Bhunia, Haripada; Bajpai, Pramod K

    2015-06-01

    Mesoporous carbon adsorbents, having high nitrogen content, were synthesized via nanocasting technique with melamine-formaldehyde resin as precursor and mesoporous silica as template. A series of adsorbents were prepared by varying the carbonization temperature from 400 to 700°C. Adsorbents were characterized thoroughly by nitrogen sorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), elemental (CHN) analysis, Fourier transform infrared (FTIR) spectroscopy and Boehm titration. Carbonization temperature controlled the properties of the synthesized adsorbents ranging from surface area to their nitrogen content, which play major role in their application as adsorbents for CO2 capture. The nanostructure of these materials was confirmed by XRD and TEM. Their nitrogen content decreased with an increase in carbonization temperature while other properties like surface area, pore volume, thermal stability and surface basicity increased with the carbonization temperature. These materials were evaluated for CO2 adsorption by fixed-bed column adsorption experiments. Adsorbent synthesized at 700°C was found to have the highest surface area and surface basicity along with maximum CO2 adsorption capacity among the synthesized adsorbents. Breakthrough time and CO2 equilibrium adsorption capacity were investigated from the breakthrough curves and were found to decrease with increase in adsorption temperature. Adsorption process for carbon adsorbent-CO2 system was found to be reversible with stable adsorption capacity over four consecutive adsorption-desorption cycles. From three isotherm models used to analyze the equilibrium data, Temkin isotherm model presented a nearly perfect fit implying the heterogeneous adsorbent surface. PMID:26040750

  1. Influence of heat-treatment on lithium ion anode properties of mesoporous carbons with nanosheet-like walls

    SciTech Connect

    Zeng, Fanyan; Hou, Zhaohui; He, Binhong; Ge, Chongyong; Cao, Jianguo; Kuang, Yafei

    2012-08-15

    Highlights: ► Mesoporous carbons possess unique nanosheet-like pore walls which can be changed by heat treatment. ► Lithium ion anode properties of mesoporous carbons could be influenced by the nanosheet-like walls. ► Mesoporous carbons with nanosheet-like walls exhibit enhanced electrochemical properties LIBs. -- Abstract: Mesoporous carbons (MCs) with nanosheet-like walls have been prepared as electrodes for lithium-ion batteries by a simple one-step infiltrating method under the action of capillary flow. The influence of heat treatment temperature on the surface topography, pore/phase structure and anode performances of as-prepared materials has been investigated. The results reveal that melted liquid-crystal polycyclic aromatic hydrocarbons could be anchored on liquid/silica interfaces by molecule engineering. After carbonization, the nanosheets are formed as the pore walls of MCs and are perpendicular to the long axis of pores. The anode properties demonstrate that C-1200 displays higher reversible capacitance than those treated in higher temperature. The rate performances of C-1200 and C-1800 are similar and more excellent than that of C-2400. These improved lithium ion anode properties could be attributed to the nanosheet-like walls of MCs which can be influenced by the heat treatment temperature.

  2. The effects of promoters of K and Zr on the mesoporous carbon supported cobalt catalysts for Fischer-Tropsch synthesis.

    PubMed

    Chen, Liang; Song, Guoxia; Fu, Yuchuan; Shen, Jianyi

    2012-02-15

    The mesoporous carbon supported cobalt catalyst (15%Co/MC) was found to be more active and selective to C(5)(+) than the traditionally activated carbon supported one (15%Co/AC) for the Fischer-Tropsch synthesis (FTS). The addition of small amount of K(2)O and ZrO(2) significantly affected the FTS behavior of 15%Co/MC. The addition of 1% K inhibited the FTS activity dramatically, while the addition of 3% Zr increased the FTS activity significantly. The addition of K(2)O decreased the surface acidity while increased the surface basicity of 15%Co/MC, resulting in the increased heat of adsorption of CO and substantially decreased heat of adsorption of H(2) on Co. In contrast, the addition of ZrO(2) increased the surface acidity and heat of adsorption of H(2) on Co. The FTS activity was found to be related to the ratio of heats for the adsorption of CO and H(2) on the catalysts 15%Co/MC, 15%Co-1%K/MC and 15%Co-3%Zr/MC. The highest FTS activity was obtained on the catalyst with the heat ratio of 1.2. PMID:22169183

  3. Mesoporous carbon-coated LiFePO4 nanocrystals co-modified with graphene and Mg2+ doping as superior cathode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Xu, Binghui; Liu, Tiefeng; Liu, Peng; Guo, Chenfeng; Wang, Shuo; Wang, Qiuming; Xiong, Zhigang; Wang, Dianlong; Zhao, X. S.

    2013-12-01

    In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg2+ 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 Mg2+ 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, Mg2+ 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.In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg2+ 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 Mg2+ 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, Mg2+ 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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr04611g

  4. Preferential adsorption of pentachlorophenol from chlorophenols-containing wastewater using N-doped ordered mesoporous carbon.

    PubMed

    Yang, Bin; Liu, Yunpeng; Li, Zhongjian; Lei, Lecheng; Zhou, Jie; Zhang, Xingwang

    2016-01-01

    Preferential removal of pentachlorophenol (PCP) from chlorophenols-containing wastewater has been attracted more attentions in wastewater treatment, since it is one of the most toxic pollutants. The adsorbent of N-doped ordered mesoporous carbon (M-OMC) with high BET surface area of 1901m(2)/g, large pore volume of 1.64cm(3)/g and uniform pore size of 3.45nm has been successfully synthesized via evaporation-induced self-assembly (EISA) method. The effects of solution pH, pore structure of adsorbent and their surface chemical properties on PCP adsorption by M-OMC were investigated in comparison with ordered mesoporous carbon (OMC), and much higher PCP adsorption capacities of M-OMC were obtained. The significantly preferential adsorption of PCP was achieved in the treatment of tri-component wastewater including PCP, p-chlorophenol (CP) and 2.4.6-trichlorophenol (TCP), and its adsorption process well fitted the pseudo-second-order kinetics model and the Langmuir isotherm. The initial sorption rate of PCP was 103.5?mol/(g/min), which was 2.97 times of TCP. It may be attributed to the intensification of ?-? interaction between PCP and M-OMC with the nitrogen functional groups. Therefore, M-OMC is promising for removal of PCP in the adsorption pretreatment of chlorophenols-containing wastewater. PMID:26374540

  5. Adsorption removal of acid black 1 from aqueous solution using ordered mesoporous carbon

    NASA Astrophysics Data System (ADS)

    Peng, Xiaoming; Hu, Xijun; Fu, Dafang; Lam, Frank L. Y.

    2014-03-01

    A novel ordered mesoporous carbon CMK-3 and synthetic CMK-3 containing nitrogen functional groups by ammonia-treated were applied for acid black 1(AB1) dye adsorption. The ammonia-treated(chemical vapor deposition method) before and after CMK-3 were characterized by using a Micrometitics ASAP 2020 surface area analyzer (ASAP 2020), Fourier transform infrared spectrophotometer (FT-IR), X-ray Photoelectron Spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscope (SEM) and equilibrium studies. This result indicates that the prepared CMK-3 and modified CMK-3 were almost uniform, as rope-like domains and their uniform mesopore with diameter centered at 3.2 nm and 3.7 nm. The FIIR analysis depicted that the presence of a variety of new basic functional groups on the modified CMK-3 surface. Several effect variables of pH, dye concentration and temperature were studied. The pseudo second-order model showed the fitter well to agree with the kinetic data. The experimental data were analyzed by the Langmuir and Freundlich models, with the latter found to closely the isotherm model. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. The results show that CMK-3 using ammonia gas modified by thermal treatment system is an effective method to improvement capacity as it shows the highest adsorption capacity of AB1, as compared to the unmodified CMK-3 and the bamboo-based carbon, respectively.

  6. Spherical nitrogen-doped hollow mesoporous carbon as an efficient bifunctional electrocatalyst for Zn-air batteries.

    PubMed

    Hadidi, Lida; Davari, Elaheh; Iqbal, Muhammad; Purkait, Tapas K; Ivey, Douglas G; Veinot, Jonathan G C

    2015-12-28

    Materials based upon porous carbon have gained considerable attention due to their high surface area, electric conductivity, thermal and chemical stability, low density, and availability. These superior properties make them ideal for diverse applications. Doping these carbon nanostructures holds promise of designing the properties of these structures and opening the door to practical applications. Herein, we report the preparation of hollow N-doped mesoporous carbon (HMC) spheres fabricated via polymerization and carbonization of dopamine on a sacrificial spherical SiO(2) template that is removed upon hydrofluoric acid etching. The morphology and structural features of these HMCs were evaluated using scanning electron microscopy and transmission electron microscopy and the N-doping (7.1 at%) was confirmed by X-ray photoelectron spectroscopy (XPS). The oxygen reduction/evolution reaction (ORR/OER) performance of N-doped HMC was evaluated using rotating disk electrode (RDE) voltammetry in an alkaline electrolyte. N-doped HMC demonstrated a high ORR onset potential of -0.055 V (vs. Hg/HgO) and excellent stability. The outstanding bifunctional activity was implemented in a practical Zn-air battery (ZAB), which exhibited a small charge-discharge voltage polarization of 0.89 V and high stability over repeated cycling. PMID:26585893

  7. 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. PMID:24287590

  8. Gold nanoparticles supported in zirconia-ceria mesoporous thin films: a highly active reusable heterogeneous nanocatalyst.

    PubMed

    Violi, Ianina L; Zelcer, Andrés; Bruno, Mariano M; Luca, Vittorio; Soler-Illia, Galo J A A

    2015-01-21

    Gold nanoparticles (NP) trapped in the mesopores of mixed zirconia-ceria thin films are prepared in a straightforward and reproducible way. The films exhibit enhanced stability and excellent catalytic activity in nitro-group reduction by borohydride and electrocatalytic activity in CO and ethanol oxidation and oxygen reduction. PMID:25522210

  9. Rapid (<3 min) microwave synthesis of block copolymer templated ordered mesoporous metal oxide and carbonate films using nitrate-citric acid systems.

    PubMed

    Zhang, Yuanzhong; Bhaway, Sarang M; Wang, Yi; Cavicchi, Kevin A; Becker, Matthew L; Vogt, Bryan D

    2015-03-25

    Rapid chemical transformation from micelle templated precursors (metal nitrate and citric acid) to ordered mesoporous metal carbonates and oxides is demonstrated using microwave heating for cobalt, copper, manganese and zinc. Without aging requirements, <3 min of microwave processing yields highly ordered mesoporous films. PMID:25714045

  10. Electrochemical control of ion transport through a mesoporous carbon membrane

    SciTech Connect

    Surwade, Sumedh P; Chai, Songhai; Choi, Jai-Pil; Wang, Xiqing; Lee, Jeseung; Vlassiouk, Ivan V; Mahurin, Shannon Mark; Dai, Sheng

    2014-01-01

    The transport of fluids through nanometer scale channels typically on the order of 1 -100 nm often exhibit unique properties compared to the bulk fluid. These phenomena occur because the channel dimensions and molecular size become comparable to the range of several important forces including electrostatic and van der Waals forces. Small changes in properties such as the electric double layer or surface charge can significantly affect molecular transport through the channels. Based on these emerging properties, a variety of nanofluidic devices such as nanofluidic transistors, nanofluidic diodes or lab-on-a-chip devices have been developed3-7 with a diverse range of applications including water purification, biomolecular sensing, DNA separation, and rectified ion transport. Nanofluidic devices are typically fabricated using expensive lithography techniques or sacrificial templates. Here we report a carbon-based, three-dimensional nanofluidic transport membrane that enables gated, or on/off, control of the transport of organic molecular species and metal ions using an applied electrical potential. In the absence of an applied potential, both cationic and anionic molecules freely diffuse across the membrane via a concentration gradient. However, when an electrochemical potential is applied, the transport of ions through the membrane is inhibited.

  11. Hierarchical mesoporous nickel cobaltite nanoneedle/carbon cloth arrays as superior flexible electrodes for supercapacitors

    PubMed Central

    2014-01-01

    Hierarchical mesoporous NiCo2O4 nanoneedle arrays on carbon cloth have been fabricated by a simple hydrothermal approach combined with a post-annealing treatment. Such unique array nanoarchitectures exhibit remarkable electrochemical performance with high capacitance and desirable cycle life at high rates. When evaluated as an electrode material for supercapacitors, the NiCo2O4 nanoneedle arrays supported on carbon cloth was able to deliver high specific capacitance of 660 F g-1 at current densities of 2 A g-1 in 2 M KOH aqueous solution. In addition, the composite electrode shows excellent mechanical behavior and long-term cyclic stability (91.8% capacitance retention after 3,000 cycles). The fabrication method presented here is facile, cost-effective, and scalable, which may open a new pathway for real device applications. PMID:24661431

  12. A novel mesoporous carbon-silica-titania nanocomposite as a high performance anode material in lithium ion batteries.

    PubMed

    Zhou, Yuanyuan; Kim, Younghun; Jo, Changshin; Lee, Jinwoo; Lee, Chul Wee; Yoon, Songhun

    2011-05-01

    An ordered mesoporous carbon-silica-titania material was prepared using the tetra-constituents co-assembly method. As regards its anode performance in lithium ion batteries, the composite material anode exhibited a high capacity (875 mAh g(-1)), a higher initial efficiency (56%) and an improved rate. PMID:21424009

  13. Mesoporous CLEAs-silica composite microparticles with high activity and enhanced stability.

    PubMed

    Cui, Jiandong; Jia, Shiru; Liang, Longhao; Zhao, Yamin; Feng, Yuxiao

    2015-01-01

    A novel enzyme immobilization approach was used to generate mesoporous enzymes-silica composite microparticles by co-entrapping gelatinized starch and cross-linked phenylalanine ammonia lyase (PAL) aggregates (CLEAs) containing gelatinized starch into biomemitic silica and subsequently removing the starch by ?-amylase treatment. During the preparation process, the gelatinzed starch served as a pore-forming agent to create pores in CLEAs and biomimetic silica. The resulting mesoporous CLEAs-silica composite microparticles exhibited higher activity and stability than native PAL, conventional CLEAs, and PAL encapsulated in biomimetic silica. Furthermore, the mesoporous CLEAs-silica composite microparticles displayed good reusability due to its suitable size and mechanical properties, and had excellent stability for storage. The superior catalytic performances were attributed to the combinational unique structure from the intra-cross-linking among enzyme aggregates and hard mesoporous silica shell, which not only decreased the enzyme-support negative interaction and mass-transfer limitations, but also improved the mechanical properties and monodispersity. This approach will be highly beneficial for preparing various bioactive mesoporous composites with excellent catalytic performance. PMID:26374188

  14. Mesoporous CLEAs-silica composite microparticles with high activity and enhanced stability

    PubMed Central

    Cui, Jiandong; Jia, Shiru; Liang, Longhao; Zhao, Yamin; Feng, Yuxiao

    2015-01-01

    A novel enzyme immobilization approach was used to generate mesoporous enzymes-silica composite microparticles by co-entrapping gelatinized starch and cross-linked phenylalanine ammonia lyase (PAL) aggregates (CLEAs) containing gelatinized starch into biomemitic silica and subsequently removing the starch by α-amylase treatment. During the preparation process, the gelatinzed starch served as a pore-forming agent to create pores in CLEAs and biomimetic silica. The resulting mesoporous CLEAs-silica composite microparticles exhibited higher activity and stability than native PAL, conventional CLEAs, and PAL encapsulated in biomimetic silica. Furthermore, the mesoporous CLEAs-silica composite microparticles displayed good reusability due to its suitable size and mechanical properties, and had excellent stability for storage. The superior catalytic performances were attributed to the combinational unique structure from the intra-cross-linking among enzyme aggregates and hard mesoporous silica shell, which not only decreased the enzyme-support negative interaction and mass-transfer limitations, but also improved the mechanical properties and monodispersity. This approach will be highly beneficial for preparing various bioactive mesoporous composites with excellent catalytic performance. PMID:26374188

  15. In situ deposition of Prussian blue on mesoporous carbon nanosphere for sensitive electrochemical immunoassay.

    PubMed

    Lai, Guosong; Zhang, Haili; Yu, Aimin; Ju, Huangxian

    2015-12-15

    A Prussian blue (PB) functionalized mesoporous carbon nanosphere (MCN) composite was prepared for loading signal antibody and high-content glucose oxidase (GOD) to obtain a new nanoprobe for sensitive electrochemical immunoassay. The MCN nanocarrier with an average diameter of 180 nm was synthesized by using mesoporous silica nanosphere as a hard template in combination with a hydrothermal carbonization method. This hydrophilic carbon nanomaterial provided an ideal platform for in situ deposition of high-content PB to form the MCN-PB nanocomposite. Based on the step-wise assembly of polyelectrolyte and gold nanoparticles (Au NPs) on the negative-charged nanocomposite, signal antibody and high-content GOD were loaded on this nanocarrier to obtain the nanoprobe. After a sandwich immunoreaction at an Au NPs-modified screen-printed carbon electrode based immunosensor, the nanoprobes were quantitatively captured on the electrode surface to produce sensitive electrochemical response with a PB-mediated GOD catalytic reaction for immunoassay. The high loading of PB and GOD on the nanoprobe greatly amplified the electrochemical signal, leading to the development of a new immunoassay method with high sensitivity. Using human immunoglobulin G as a model analyte, excellent analytical performance including a wide linear range from 0.01 to 100 ng/mL and a low detection limit down to 7.8 pg/mL was obtained. Additionally, the immunosensor showed high specificity, satisfactory stability and repeatability as well as acceptable reliability. The PB-mediated GOD electrochemical system well excluded the conventional interference from the dissolved oxygen. Thus this immunoassay method provides great potentials for practical applications. PMID:26201983

  16. Three dimensionally ordered mesoporous carbon as a stable, high-performance Li-O? battery cathode.

    PubMed

    Xie, Jin; Yao, Xiahui; Cheng, Qingmei; Madden, Ian P; Dornath, Paul; Chang, Chun-Chih; Fan, Wei; Wang, Dunwei

    2015-03-27

    Enabled by the reversible conversion between Li2O2 and O2, Li-O2 batteries promise theoretical gravimetric capacities significantly greater than Li-ion batteries. The poor cycling performance, however, has greatly hindered the development of this technology. At the heart of the problem is the reactivity exhibited by the carbon cathode support under cell operation conditions. One strategy is to conceal the carbon surface from reactive intermediates. Herein, we show that long cyclability can be achieved on three dimensionally ordered mesoporous (3DOm) carbon by growing a thin layer of FeO(x) using atomic layer deposition (ALD). 3DOm carbon distinguishes itself from other carbon materials with well-defined pore structures, providing a unique material to gain insight into processes key to the operations of Li-O2 batteries. When decorated with Pd?nanoparticle catalysts, the new cathode exhibits a capacity greater than 6000?mAh?g(carbon) (-1) and cyclability of more than 68?cycles. PMID:25676920

  17. A co-sol-emulsion-gel synthesis of tunable and uniform hollow carbon nanospheres with interconnected mesoporous shells

    NASA Astrophysics Data System (ADS)

    Hou, Jianhua; Cao, Tai; Idrees, Faryal; Cao, Chuanbao

    2015-12-01

    Monodispersed mesoporous hollow spheres of polymer-silica and carbon-silica nanocomposites with an ``interpenetration twin'' nanostructure have been successfully synthesized by a co-sol-emulsion-gel method. The obtained mesoporous hollow carbon spheres (MHCSs) exhibited an open interconnected mesoporous shell that is endowed with high specific surface area (SBET, 2106-2225 m2 g-1) and large pore volume (1.95-2.53 cm3 g-1). Interestingly, the diameter of the uniform MHCSs could be precisely tuned on demand, as an effective electrode material in supercapacitors, MHCSs with a diameter of 90 nm deliver the shortest time constant (τ0 = 0.75 s), which is highly beneficial for rate capacitance (180 F g-1 at 100 A g-1, a full charge-discharge within 0.9 s) and cyclic retainability (3% loss after 20 000 cycles). The newly developed synthesis route leads to unique interconnected mesoporous hollow carbonaceous spheres with open-framework structures, providing a new material platform in energy storage.Monodispersed mesoporous hollow spheres of polymer-silica and carbon-silica nanocomposites with an ``interpenetration twin'' nanostructure have been successfully synthesized by a co-sol-emulsion-gel method. The obtained mesoporous hollow carbon spheres (MHCSs) exhibited an open interconnected mesoporous shell that is endowed with high specific surface area (SBET, 2106-2225 m2 g-1) and large pore volume (1.95-2.53 cm3 g-1). Interestingly, the diameter of the uniform MHCSs could be precisely tuned on demand, as an effective electrode material in supercapacitors, MHCSs with a diameter of 90 nm deliver the shortest time constant (τ0 = 0.75 s), which is highly beneficial for rate capacitance (180 F g-1 at 100 A g-1, a full charge-discharge within 0.9 s) and cyclic retainability (3% loss after 20 000 cycles). The newly developed synthesis route leads to unique interconnected mesoporous hollow carbonaceous spheres with open-framework structures, providing a new material platform in energy storage. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06279a

  18. Synthesis of ordered mesoporous carbon molecular sieve and its adsorption capacity for H 2, N 2, O 2, CH 4 and CO 2

    NASA Astrophysics Data System (ADS)

    Zhou, Li; Liu, Xiuwu; Li, Jingwen; Wang, Ning; Wang, Zhen; Zhou, Yaping

    2005-09-01

    Ordered mesoporous carbon is a recently developed material. To test its potential application for adsorption, such a material was synthesized using silica SBA-15 as the template and sucrose as the carbon source. The ordered structure and the mesopore dimension of the material were proven with XRD, SEM and TEM examinations. Adsorption data of H 2, N 2, O 2, CH 4 and CO 2 on the ordered mesoporous carbon were collected with a typical volumetric method for a pressure range up to 11 MPa. Potential application for the separation of CO 2-CH 4-air mixture was indicated.

  19. The performance of supercapacitor electrodes developed from chemically activated carbon produced from waste tea

    NASA Astrophysics Data System (ADS)

    Inal, I. Isil Gurten; Holmes, Stuart M.; Banford, Anthony; Aktas, Zeki

    2015-12-01

    Highly microporous and mesoporous activated carbons were produced from waste tea for application as supercapacitor electrodes, utilising a chemical activation method involving treatment with either K2CO3 or H3PO4. The area, pore structure characteristics and surface functionality of the activated carbons were evaluated to investigate the influence on electrochemical performance. The performance of the activated carbons as supercapacitor electrodes was tested by cyclic voltammetry (CV), impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD) measurements, in an aqueous electrolyte. The results showed that the pore structure and type of the activated carbon have significant impact on the supercapacitor performance. Both waste tea-based activated carbon electrodes showed good cyclic stability. However, despite its lower specific surface area the highly microporous activated carbon produced with K2CO3, exhibited much better capacitive performance than that of the mesoporous activated carbon produced with H3PO4.

  20. Facile control of long range orientation in mesoporous carbon films with thermal zone annealing velocity

    NASA Astrophysics Data System (ADS)

    Xue, Jiachen; Singh, Gurpreet; Qiang, Zhe; Yager, Kevin G.; Karim, Alamgir; Vogt, Bryan D.

    2013-11-01

    Ordered mesoporous carbons exhibit appealing properties for many applications, but their function and performance can depend critically on their structure. The in-plane orientation of 2D cylinders from the cooperative assembly of Pluronic P123 and resol has been controlled by application of cold zone annealing (CZA). By varying the moving rate, the preferential in-plane orientation of the self-assembled cylinders can be tuned through the entire 180° range possible from φ = 50° to φ = -130° (relative to the moving direction). At a moving rate of 2 μm s-1, this simple and easy CZA process leads to cylinders that are well aligned parallel to the moving direction with a high orientational factor of S = 0.98. Moreover, the in-plane oriented cylinders can be nearly perfectly aligned transverse to the moving direction (S = 0.95) by simply decreasing the moving velocity to 0.5 μm s-1. We attribute the parallel alignment to the flow that develops from the motion of the thermal gradients, while the transverse alignment is related to flow cessation (inertial effect). The preferential orientation is retained through the carbonization process, but there is some degradation in orientation due to insufficient crosslinking of the resol during CZA; this effect is most prominent for the higher moving rates (less time for crosslinking), but can be overcome by post-CZA annealing at uniform elevated temperatures to further crosslink the resol. CZA is a simple and powerful method for fabricating well-aligned and self-assembled mesoporous carbon films over large areas.Ordered mesoporous carbons exhibit appealing properties for many applications, but their function and performance can depend critically on their structure. The in-plane orientation of 2D cylinders from the cooperative assembly of Pluronic P123 and resol has been controlled by application of cold zone annealing (CZA). By varying the moving rate, the preferential in-plane orientation of the self-assembled cylinders can be tuned through the entire 180° range possible from φ = 50° to φ = -130° (relative to the moving direction). At a moving rate of 2 μm s-1, this simple and easy CZA process leads to cylinders that are well aligned parallel to the moving direction with a high orientational factor of S = 0.98. Moreover, the in-plane oriented cylinders can be nearly perfectly aligned transverse to the moving direction (S = 0.95) by simply decreasing the moving velocity to 0.5 μm s-1. We attribute the parallel alignment to the flow that develops from the motion of the thermal gradients, while the transverse alignment is related to flow cessation (inertial effect). The preferential orientation is retained through the carbonization process, but there is some degradation in orientation due to insufficient crosslinking of the resol during CZA; this effect is most prominent for the higher moving rates (less time for crosslinking), but can be overcome by post-CZA annealing at uniform elevated temperatures to further crosslink the resol. CZA is a simple and powerful method for fabricating well-aligned and self-assembled mesoporous carbon films over large areas. Electronic supplementary information (ESI) available: GISAXS patterns for additional azimuthal angles, individual Gaussian fits of the azimuthal dependence on the primary diffraction intensity, ellipsometry data for CZA films and ellipsometry line scan illustrating the thicknesses associated with the static thermal gradient exposure. See DOI: 10.1039/c3nr03591c

  1. Hierarchically mesoporous CuO/carbon nanofiber coaxial shell-core nanowires for lithium ion batteries

    PubMed Central

    Park, Seok-Hwan; Lee, Wan-Jin

    2015-01-01

    Hierarchically mesoporous CuO/carbon nanofiber coaxial shell-core nanowires (CuO/CNF) as anodes for lithium ion batteries were prepared by coating the Cu2(NO3)(OH)3 on the surface of conductive and elastic CNF via electrophoretic deposition (EPD), followed by thermal treatment in air. The CuO shell stacked with nanoparticles grows radially toward the CNF core, which forms hierarchically mesoporous three-dimensional (3D) coaxial shell-core structure with abundant inner spaces in nanoparticle-stacked CuO shell. The CuO shells with abundant inner spaces on the surface of CNF and high conductivity of 1D CNF increase mainly electrochemical rate capability. The CNF core with elasticity plays an important role in strongly suppressing radial volume expansion by inelastic CuO shell by offering the buffering effect. The CuO/CNF nanowires deliver an initial capacity of 1150 mAh g−1 at 100 mA g−1 and maintain a high reversible capacity of 772 mAh g−1 without showing obvious decay after 50 cycles. PMID:25944615

  2. Ultrafine ferroferric oxide nanoparticles embedded into mesoporous carbon nanotubes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Gao, Guo; Zhang, Qiang; Cheng, Xin-Bing; Shapter, Joseph G.; Yin, Ting; Sun, Rongjin; Cui, Daxiang

    2015-12-01

    An effective one-pot hydrothermal method for in situ filling of multi-wall carbon nanotubes (CNT, diameter of 20-40 nm, length of 30-100 μm) with ultrafine ferroferric oxide (Fe3O4) nanoparticles (8-10 nm) has been demonstrated. The synthesized Fe3O4@CNT exhibited a mesoporous texture with a specific surface area of 109.4 m2 g-1. The loading of CNT, in terms of the weight ratio of Fe3O4 nanoparticles, can reach as high as 66.5 wt%. Compared to the conventional method of using a Al2O3 membrane as template to fill CNT with iron oxides nanoparticles, our strategy is facile, effective, low cost and easy to scale up to large scale production (~1.42 g per one-pot). When evaluated for lithium storage at 1.0 C (1 C = 928 mA g-1), the mesoporous Fe3O4@CNT can retain at 358.9 mAh g-1 after 60 cycles. Even when cycled at high rate of 20 C, high capacity of 275.2 mAh g-1 could still be achieved. At high rate (10 C) and long life cycling (500 cycles), the cells still exhibit a good capacity of 137.5 mAhg-1.

  3. Covalent entrapment of cobalt-iron sulfides in N-doped mesoporous carbon: extraordinary bifunctional electrocatalysts for oxygen reduction and evolution reactions.

    PubMed

    Shen, Mengxia; Ruan, Changping; Chen, Yan; Jiang, Chunhuan; Ai, Kelong; Lu, Lehui

    2015-01-21

    To alleviate the kinetic barriers associated with ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) in electrochemical systems, efficient nonprecious electrocatalysts are urgently required. Here we report a facile soft-template mediated approach for fabrication of nanostructured cobalt-iron double sulfides that are covalently entrapped in nitrogen-doped mesoporous graphitic carbon (Co0.5Fe0.5S@N-MC). Notably, with a positive half-wave potential (0.808 V) and a high diffusion-limiting current density, the composite material delivers unprecedentedly striking ORR electrocatalytic activity among recently reported nonprecious late transition metal chalcogenide materials in alkaline medium. Various characterization techniques, including X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, are conducted to elucidate the correlation between structural features and catalytic activities of the composite. Moderate substitution and well-dispersion of iron in bimetallic sulfide composites are believed to have positive effect on the adsorption and activation of oxygen-containing species, thus leading to conspicuous ORR and OER catalytic enhancement compared to their monometallic counterparts. Besides, the covalent bridge between active sulfide particles and mesoporous carbon shells provides facile pathways for electron and mass transport. Beneficially, the intimate coupling interaction renders prolonged electrocatalytic performances to the composite. Our results may possibly lend a new impetus to the rational design of bi- or multimetallic sulfides encapsulated in porous carbon with improved performance for electrocatalysis and energy storage applications. PMID:25531776

  4. Improved cycling stability of lithium-sulfur batteries using a polypropylene-supported nitrogen-doped mesoporous carbon hybrid separator as polysulfide adsorbent

    NASA Astrophysics Data System (ADS)

    Balach, Juan; Jaumann, Tony; Klose, Markus; Oswald, Steffen; Eckert, Jürgen; Giebeler, Lars

    2016-01-01

    The lithium/sulfur couple is garnering tremendous interest as the next-generation of cost-efficient rechargeable battery systems capable to fulfill emerging energy storage demands. However, the viable commercialization of lithium-sulfur (Li-S) batteries is still an obstacle by fast capacity fading and poor cycling stability mostly caused by the polysulfide shuttle and active sulfur material loss. In this contribution, we show that the surface modification of the commercial polypropylene separator with a nitrogen-doped mesoporous carbon enhances the interfacial interaction between the N-dopants on carbon-coating and the sulfur-related species by coupling interactions. These unique physical and interfacial chemical properties of the N-doped mesoporous carbon-coating promote the chemical adsorption and confinement of lithium (poly)sulfide intermediates in the cathode side, improving the active material utilization and hence the overall electrochemical performance of Li-S batteries: high initial discharge capacity of 1364 mAh g-1 at 0.2C and notable cycling stability with high reversible capacity of 566 mAh g-1 and negligible degradation rate of 0.037% after 1200 cycles at 0.5C. Furthermore, despite the use of a simple-mixed sulfur-carbon black cathode with high-sulfur loading of 3.95 mg cm-2, the cell with a hybrid separator delivers a high areal capacity of ˜3 mAh cm-2.

  5. Carbon-Free CoO Mesoporous Nanowire Array Cathode for High-Performance Aprotic Li-O2 Batteries.

    PubMed

    Wu, Baoshan; Zhang, Hongzhang; Zhou, Wei; Wang, Meiri; Li, Xianfeng; Zhang, Huamin

    2015-10-21

    Although various kinds of catalysts have been developed for aprotic Li-O2 battery application, the carbon-based cathodes are still vulnerable to attacks from the discharge intermediates or products, as well as the accompanying electrolyte decomposition. To ameliorate this problem, the free-standing and carbon-free CoO nanowire array cathode was purposely designed for Li-O2 batteries. The single CoO nanowire formed as a special mesoporous structure, owing even comparable specific surface area and pore volume to the typical Super-P carbon particles. In addition to the highly selective oxygen reduction/evolution reactions catalytic activity of CoO cathodes, both excellent discharge specific capacity and cycling efficiency of Li-O2 batteries were obtained, with 4888 mAh gCoO(-1) and 50 cycles during 500 h period. Owing to the synergistic effect between elaborate porous structure and selective intermediate absorption on CoO crystal, a unique bimodal growth phenomenon of discharge products was occasionally observed, which further offers a novel mechanism to control the formation/decomposition morphology of discharge products in nanoscale. This research work is believed to shed light on the future development of high-performance aprotic Li-O2 batteries. PMID:26400109

  6. Shape Control of Mesoporous Silica Nanomaterials Templated with Dual Cationic Surfactants and Their Antibacterial Activities

    PubMed Central

    Hao, Nanjing; Chen, Xuan; Jayawardana, Kalana W.; Wu, Bin; Sundhoro, Madanodaya; Yan, Mingdi

    2015-01-01

    Mesoporous silica nanomaterials of different shapes (film, platelet, sphere, rod) were synthesized simply by tuning the mole ratio of dual cationic surfactant templates, cetyltrimethylammonium bromide (CTAB) and tetrabutylammonium iodine (TBAI). The film showed the most potent antibacterial activities against mycobacteria. PMID:26364920

  7. The Local and Surface Structure of Ordered Mesoporous Carbons from Nitrogen Sorption, NEXAFS and Synchrotron Radiation Studies

    SciTech Connect

    Smith,M.; Lobo, R.

    2006-01-01

    Ordered mesoporous carbon materials were prepared by pyrolysis of sucrose and furfuryl alcohol templated in the ordered mesoporous silicate SBA-15. The structure of SBA-15 template was modified by changing the calcination temperature, we investigate the structural transformation of the silica template with calcination temperature using X-ray diffraction and nitrogen adsorption isotherms. SBA-15 calcined to 300 C has a total pore volume of 1.13 cm{sup 3}/g, a BET surface area of 1100 m2/g, and a pore spacing of 114 Angstroms; when calcined to 90 C the corresponding values are 0.40 cm{sup 3}/g, 330 m{sup 2}/g and 92.5 Angstroms. Despite marked differences in SBA-15 template structure, the pore size distribution of the ordered mesoporous carbons is more dependent on the choice of precursor than on SBA-15 pore geometry. The BET surface areas of ordered mesoporous carbons made from aqueous sucrose solutions (850-1050 m2/g) are independent of template geometry; while surface area of materials made from furfuryl alcohol (530-1190 m2/g) are a reflection of template geometry. Near-edge X-ray fine-structure (NEXAFS) spectroscopy reveal that the template-carbon interaction during the pyrolysis of sucrose-based carbons exerts a strong influence on the surface structure of final product, and that such effects are largely absent in the furfuryl alcohol-based materials. The pair-distribution function (PDF) calculated from high-energy synchrotron scattering measurements corroborates the NEXAFS results, yet also show that the template effect on the bulk carbon is minimal. Template compression acting in conjunction with hydrothermally induced effects exerted on the carbon during pyrolysis drives the resulting carbon to a more graphitic state.

  8. Electrochemical determination of bisphenol A at ordered mesoporous carbon modified nano-carbon ionic liquid paste electrode.

    PubMed

    Li, Yonghong; Zhai, Xiurong; Liu, Xinsheng; Wang, Ling; Liu, Herong; Wang, Haibo

    2016-02-01

    A simple bisphenol A (BPA) sensor was successfully fabricated based on ordered mesoporous carbon CMK-3 modified nano-carbon ionic liquid paste electrode (CMK-3/nano-CILPE). The nanostructure of CMK-3 and the surface morphologies of modified electrodes were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Electrochemical properties of the fabricated electrodes were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The fabricated sensor displayed excellent electroactivity towards bisphenol A using linear sweep voltammetry (LSV). Experimental conditions influencing the analytical performance of the modified electrode were optimized. Under optimal conditions, the oxidation peak current was proportional to BPA concentration in the range from 0.2 μM to 150 μM with a detection limit of 0.05 μM (S/N=3). This method was successfully used for determination of BPA leached from drinking bottle and plastic bag with good recoveries. PMID:26653461

  9. Entrapping cross-linked glucose oxidase aggregates within a graphitized mesoporous carbon network for enzymatic biofuel cells.

    PubMed

    Garcia-Perez, Tsai; Hong, Sung-Gil; Kim, Jungbae; Ha, Su

    2016-08-01

    This paper reports a novel method for producing glucose oxidase-nanocomposites by entrapping cross-linked glucose oxidase (GOx) aggregates within a graphitized mesoporous carbon (GMC) network. Entrapment was achieved by utilizing the strong self-aggregation tendency of GMC in aqueous buffer solution to form carbon networks. Using confocal microscopy and TEM, GOx-GMC nanocomposites were visualized. The electrochemical properties of GOx-GMC nanocomposites were studied by means of cyclic voltammograms, chronoamperometric and potentiostatic tests. Results therefrom suggested that the GOx-GMC nanocomposites offer a high electrical conductivity with the maximum electron transfer rate constant estimated at 5.16±0.61s(-1). Furthermore, thermally treating the GOx-GMC nanocomposite and GOx aggregates at 60°C for four hours, both samples maintained 99% of their initial activity, while the free GOx were completely deactivated. These performances suggested that our nanocomposite structure offered both improved electrochemical performance and stability by combining the high electrical conductivity offered by the GMC network with the high enzyme loading and stability offered by the cross-linked GOx aggregates. The GOx-GMC nanocomposite's electrochemical activity towards glucose oxidation was also investigated by using an enzymatic biofuel cell without artificial mediators, producing a power density of up to 22.4μWcm(-2) at 0.24V. PMID:27241289

  10. Combined Au-plasmonic nanoparticles with mesoporous carbon material (CMK-3) for photocatalytic water splitting

    SciTech Connect

    Hung, Wei Hsuan E-mail: yinm@sari.ac.cn; Lai, Sz Nian; Su, Cheng Yi; Yin, Min E-mail: yinm@sari.ac.cn; Li, Dongdong; Xue, Xinzhong; Tseng, Chuan Ming

    2015-08-17

    The conventional TiO{sub 2} photoelectrode for water splitting was integrated with ordered mesoporous carbon material (CMK-3) and Au metal nanoparticles (NPs) to improve the photocatalytic efficiency under visible light irradiation. Compared to TiO{sub 2}, Au/TiO{sub 2}-CMK-3 photoelectrode demonstrated over two orders of magnitude enhancement of photocurrent under 532 nm laser irradiation due to the generation of hot electron and near field from Au NPs. Furthermore, the improvement of free carrier transport and additional long-wavelength absorption can be achieved by exploiting the superior conductivity and blackbody-like property of CMK-3. This proposed enhancement mechanism was proved by the measurements of photoluminescence emission spectrum and electrochemical impedance spectroscopy.

  11. Electromagnetic interference (EMI) shielding of ordered mesoporous carbon (OMC)/paraffin composites.

    PubMed

    Wu, Hongjing; Wang, Liuding; Zhang, Jiangdong; Wei, Gao; Guo, Shaoli; Shen, Zhongyuan

    2014-08-01

    The ordered mesoporous carbon (OMC)/paraffin composites were successfully prepared by a facile physical mixing method and an EMI SE of 21-23 dB was achieved at the OMC loading of 5.69 wt.% in the X band. This indicates that the composites are very suitable for an application as effective and lightweight EMI shielding materials. The EMI shielding of the composite shows an absorption-dominant mechanism, i.e., a contribution shift from reflection to absorption is observed with the increase in OMC loading and frequency. This could be explained by the intrinsic properties (electrical conductivity, complex permittivity and potential large defects) and novel structure of the composites. PMID:25936048

  12. Combined Au-plasmonic nanoparticles with mesoporous carbon material (CMK-3) for photocatalytic water splitting

    NASA Astrophysics Data System (ADS)

    Hung, Wei Hsuan; Lai, Sz Nian; Su, Cheng Yi; Yin, Min; Li, Dongdong; Xue, Xinzhong; Tseng, Chuan Ming

    2015-08-01

    The conventional TiO2 photoelectrode for water splitting was integrated with ordered mesoporous carbon material (CMK-3) and Au metal nanoparticles (NPs) to improve the photocatalytic efficiency under visible light irradiation. Compared to TiO2, Au/TiO2-CMK-3 photoelectrode demonstrated over two orders of magnitude enhancement of photocurrent under 532 nm laser irradiation due to the generation of hot electron and near field from Au NPs. Furthermore, the improvement of free carrier transport and additional long-wavelength absorption can be achieved by exploiting the superior conductivity and blackbody-like property of CMK-3. This proposed enhancement mechanism was proved by the measurements of photoluminescence emission spectrum and electrochemical impedance spectroscopy.

  13. Effects of Synthesis Process on Luminescence Properties and Structure of Mesoporous Carbon-Silica Nanocomposite

    NASA Astrophysics Data System (ADS)

    Sato, Koji; Ishikawa, Yukari; Ishii, Yosuke; Kawasaki, Shinji; Muto, Shunsuke; Yamamoto, Yuta

    2012-08-01

    The effects of hydrolysis and polycondensation reactions for synthesizing light-emitting mesoporous carbon-silica (MPCS) nanocomposite on the structure, chemical bonding state, and luminescence properties of MPCS were investigated by controlling the concentration (0.02 to 5 M) of HCl, which was used as a catalyst for hydrolysis and polycondensation. The progress of hydrolysis and polycondensation reactions provides a nanometer-order pore/wall structure and results in a strong light-emitting property. The pore/wall structure was obtained using HCl at concentrations of 0.2 M and higher, but it became disordered with increasing HCl concentration (2 and 5 M). The luminescence color of the MPCS nanocomposite can be changed from yellowish-white to bluish-white by changing the concentration of HCl.

  14. Polyaniline nanofiber/large mesoporous carbon composites as electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Liu, Huan; Xu, Bin; Jia, Mengqiu; Zhang, Mei; Cao, Bin; Zhao, Xiaonan; Wang, Yu

    2015-03-01

    A composite of polyaniline nanofiber/large mesoporous carbon (PANI-F/LMC) hybrid was prepared by an in situ chemical oxidative polymerization of aniline monomer with nano-CaCO3 templated LMC as host matrix for supercapacitors. The morphology, composition and electronic structure of the composites (PANI-F/LMC) together with pure PANI nanofibers and the LMC were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), FT-IR, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It is found that the PANI nanofibers were incorporated into the large mesochannels of LMC with interpenetrating framework formed. Such unique structure endows the PANI-F/LMC composite with a high capacitance of 473 F g-1 at a current load of 0.1 A g-1 with good rate performance and cycling stability, suggesting its potential application in the electrode material for supercapacitors.

  15. Enhanced performance of lithium sulfur battery with polypyrrole warped mesoporous carbon/sulfur composite

    NASA Astrophysics Data System (ADS)

    Ma, Guoqiang; Wen, Zhaoyin; Jin, Jun; Lu, Yan; Rui, Kun; Wu, Xiangwei; Wu, Meifen; Zhang, Jingchao

    2014-05-01

    A sulfur cathode is designed with three-dimensional (3D) cubic mesoporous carbon CMK-8 as the matrix of sulfur, and polypyrrole (PPY) as the wrapping layer. CMK-8 provides perfect 3D conductive network. Furthermore, PPY is coated onto the surface of CMK-8/sulfur (CMK-8/S) composite to inhibit the migration of lithium polysulfide and offer better lithium ion conductive channels. The microstructure and electrochemical performance of the PPY@CMK-8/sulfur (PPY@CMK-8/S) cathode are investigated systematically. The results show that PPY layer with about 50 nm thickness is coated uniformly on the surface of CMK-8/S. The Li-S battery with PPY@CMK-8/S as cathode material presents a discharge capacity of 937.8 mAh g-1 at 20 cycles and is stabilized at about 860 mAh g-1 after 100 cycles at 0.2C.

  16. Synthesis of mesoporous carbon nanoparticles with large and tunable pore sizes

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Yu, Meihua; Li, Yang; Li, Jiansheng; Wang, Jing; Yu, Chengzhong; Wang, Lianjun

    2015-07-01

    Mesoporous carbon nanoparticles (MCNs) with large and adjustable pores have been synthesized by using poly(ethylene oxide)-b-polystyrene (PEO-b-PS) as a template and resorcinol-formaldehyde (RF) as a carbon precursor. The resulting MCNs possess small diameters (100-126 nm) and high BET surface areas (up to 646 m2 g-1). By using home-designed block copolymers, the pore size of MCNs can be tuned in the range of 13-32 nm. Importantly, the pore size of 32 nm is the largest among the MCNs prepared by the soft-templating route. The formation mechanism and structure evolution of MCNs were studied by TEM and DLS measurements, based on which a soft-templating/sphere packing mechanism was proposed. Because of the large pores and small particle sizes, the resulting MCNs were excellent nano-carriers to deliver biomolecules into cancer cells. MCNs were further demonstrated with negligible toxicity. It is anticipated that this carbon material with large pores and small particle sizes may have excellent potential in drug/gene delivery.Mesoporous carbon nanoparticles (MCNs) with large and adjustable pores have been synthesized by using poly(ethylene oxide)-b-polystyrene (PEO-b-PS) as a template and resorcinol-formaldehyde (RF) as a carbon precursor. The resulting MCNs possess small diameters (100-126 nm) and high BET surface areas (up to 646 m2 g-1). By using home-designed block copolymers, the pore size of MCNs can be tuned in the range of 13-32 nm. Importantly, the pore size of 32 nm is the largest among the MCNs prepared by the soft-templating route. The formation mechanism and structure evolution of MCNs were studied by TEM and DLS measurements, based on which a soft-templating/sphere packing mechanism was proposed. Because of the large pores and small particle sizes, the resulting MCNs were excellent nano-carriers to deliver biomolecules into cancer cells. MCNs were further demonstrated with negligible toxicity. It is anticipated that this carbon material with large pores and small particle sizes may have excellent potential in drug/gene delivery. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02389k

  17. 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. PMID:25238189

  18. One-pot synthesis of silicon nanoparticles trapped in ordered mesoporous carbon for use as an anode material in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    Silicon nanoparticles trapped in an ordered mesoporous carbon composite were prepared by a one-step self-assembly with solvent evaporation using the triblock copolymer Pluronic F127 and a resorcinol-formaldehyde polymer as the templating agent and carbon precursor respectively. Such a one-pot synthesis of Si/ordered mesoporous carbon nanocomposite is suitable for large-scale synthesis. Characterization confirmed that the Si nanoparticles were trapped in the ordered mesoporous carbon, as evidenced by transmission electron microscopy, x-ray diffraction analysis and nitrogen sorption isotherms. The composite showed a high reversible capacity above 700 mA h g-1 during 50 cycles at 2 A g-1. The improved electrochemical performance of the composite can be ascribed to the buffering effect of spaces formed in the ordered pore channels during the volume expansion of silicon and the rapid movement of lithium ions through the uniform cylindrical pore structure of the mesopores.

  19. Peculiar Properties of Mesoporous Synthetic Carbon/Graphene Phase Composites and their Effect on Supercapacitive Performance.

    PubMed

    Seredych, Mykola; Rodríguez-Castellón, Enrique; Bandosz, Teresa J

    2015-06-01

    Composites of mesoporous synthetic carbon and the graphene phase were synthesized in aqueous suspension by employing dispersive interactions of both phases. The resulting carbon-based materials were further heat treated in air at 350 °C. The composites and their components were characterized by using adsorption of nitrogen, potentiometric titration, thermal analysis-mass spectrometry, X-ray photoelectron spectroscopy, SEM, high-resolution TEM, and XRD. Then, they were tested as supercapacitors in three-electrode cells and under visible-light irradiation. The composites and the initial carbon share exactly the same pore-size distributions, but they exhibit significant differences in their surface chemistry, wettability, and conductivity. This allowed us to determine the extent of their effects on their capacitive/pseudocapacitive performance. The results showed that features other than the textural properties can increase the capacitive performance by more than 100 %. The synergistic properties of the composites and their sulfur functional group related photoactivity were linked to chemical interactions between the nanoporous carbon phase and graphite oxide during the formation of the composite. PMID:25916763

  20. Optimization of mesoporous carbon structures for lithium–sulfur battery applications

    SciTech Connect

    Li, Xiaolin; Cao, Yuliang; Qi, Wen N.; Saraf, Laxmikant V.; Xiao, Jie; Nie, Zimin; Mietek, Jaroniec; Zhang, Jiguang; Schwenzer, Birgit; Liu, Jun

    2011-11-07

    Mesoporous carbon (MC) with tunable pore sizes (22nm, 12nm, 7nm, and 3nm) and pore volumes (from 1.3 to 4.8 cc/g) containing sulfur inside the pores were systematically studied as mesoporous carbon-sulfur (MCS) composite electrodes for Li-S batteries. Investigation on these MCS composites reveals that the pore structure has no influence on the battery performance at full sulfur loading conditions (the pore volume is fully filled by sulfur) but the maximum sulfur loading capability is higher for MC with larger pore volume. MC with large pore volumes, partial sulfur filling (part of the pore volume left unfilled), and surface modification, can have reasonably high sulfur loading, improved electrical and ionic contacts of sulfur with MC and with electrolytes, which subsequently promotes the battery performance. An initial capacity of ~1250 mAh/g (based on sulfur) and 650 mAh/g capacity retention over 100 cycles were obtained with 50 wt% sulfur loading in the MC with 22nm pore size (4.8 cc/g). When the surface of MCS was coated with Clevios P to reduce the dissolve of polysulfide anions in electrolytes, it exhibits a high initial discharge capacity of ~1390 mAh/g and improved cycling stability with capacity retention of ~840 mAh/g over 100 cycles. The reported correlation among the structure, sulfur filling, surface modification and the electrochemical performance of the MCS composite cathodes provides guidance in designing new electrodes for lithium-sulfur batteries

  1. A carbon foam with a bimodal micro–mesoporous structure prepared from larch sawdust for the gas-phase toluene adsorption

    SciTech Connect

    Liu, Shouxin; Huang, Zhanhua; Wang, Rui

    2013-07-15

    Highlights: ► Network carbon foam containing a bimodal pore distribution was prepared from Larch. ► Liquefaction route was used for the preparation of morphology controllable carbon. ► Pore structure of carbon foam was controlled through KOH activation. - Abstract: A carbon foam with a bimodal micro–mesopore distribution, was prepared by submitting larch sawdust to liquefaction, resinification, foaming, carbonization and KOH activation. The morphology, pore texture and crystal microstructure was characterized by scanning and transmission electron microscopy, nitrogen adsorption analysis and X-ray powder diffraction. A honeycomb structure with adjacent cells was observed for the precursor of carbon foam. After KOH activation, the cell wall of precursor shrunk and broke. This lead to the formation of a well-connected 3D network and developed ligament pore structure (surface area of 554–1918 m{sup 2}/g) containing bimodal pores, 2.1 and 3.9 nm in diameter. The porous carbon foam prepared at 700 °C exhibited a much higher gas-phase toluene removal than commercial activated carbon fiber owing to the 3D network and bimodal pore structure.

  2. Highly active Pd-In/mesoporous alumina catalyst for nitrate reduction.

    PubMed

    Gao, Zhenwei; Zhang, Yonggang; Li, Deyi; Werth, Charles J; Zhang, Yalei; Zhou, Xuefei

    2015-04-01

    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. PMID:25600582

  3. Synthesis and photocatalytic activities of Nd-doped TiO2 mesoporous microspheres

    NASA Astrophysics Data System (ADS)

    Liu, Xijian; Sun, Yangang; Wang, Yeying; Zhang, Lijuan; Lu, Jie

    2016-11-01

    Nd-doped TiO2 mesoporous microspheres with possessing regular micro/nanostructure were synthesized by a simple and facile method. The structure and optical properties of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption isotherms and UV-Visible absorbance spectroscopy. It was revealed that Nd-doped TiO2 mesoporous microspheres are composed of primary nanoparticles with a particle size of ˜25nm. The photocatalytic activities of all the samples were evaluated by degradation methyl orange (MO) in aqueous solution as a model reaction under xenon lamp light irradiation. The results showed that the doped samples demonstrated a higher photocatalytic activity than TiO2 mesoporous microspheres, and the MO of 10mg/mL almost could be completely degraded by the Nd-doped TiO2 mesoporous sample (the dosage of Nd salt to TiO2 is 6%) under xenon lamp light irradiation within 1h.

  4. Efficient Photocatalytic Activities of TiO2 Hollow Fibers with Mixed Phases and Mesoporous Walls

    PubMed Central

    Hou, Huilin; Shang, Minghui; Wang, Lin; Li, Wenge; Tang, Bin; Yang, Weiyou

    2015-01-01

    Currently, Degussa P25, with the typical mixed phases of anatase and rutile TiO2, is widely applied as the commercial photocatalysts. However, there are still some of obstacles for the P25 nanoparticles with totally high photocatalytic activities, especially for the catalytic stability due to their inevitable aggregation of the nanoparticles when used as the photocatalysts. In the present work, we reported the exploration of a novel TiO2 photocatalyst, which could offer an ideal platform for synergetic combination of the mixed-phase composition, hollow architecture and mesoporous walls for the desired excellent photocatalytic efficiency and robust stability. The mesoporous TiO2 hollow nanofibers were fabricated via a facile single capillary electrospinning technique, in which the foaming agents were used for creating mesopores throughout the walls of the hollow fibers. The obtained hollow fibers exhibit a high purity and possess the mixed phases of 94.6% anatase and 5.4% rutile TiO2. As compared to P25, the as-fabricated mesoporous TiO2 hollow fibers exhibited much higher efficient photocatalytic activities and stabilities toward the hydrogen evolution with a rate of ~499.1 μmol g−1·h−1 and ~99.5% degradation Rhodamine B (RhB) in 60 min, suggesting their promising application in efficient photocatalysts. PMID:26470013

  5. Thermal and mechanical properties of novel nanocomposites from modified ordered mesoporous carbon FDU-15 and poly(methyl methacrylate)

    NASA Astrophysics Data System (ADS)

    Mohammadnezhad, Gholamhossein; Dinari, Mohammad; Soltani, Roozbeh; Bozorgmehr, Zahra

    2015-08-01

    With its well-ordered pore structure, high specific surface area and tunable pore diameters, ordered mesoporous carbons are suitable for applications in many areas of modern science and technology. In the present investigation, an ultrasonic irradiation was used for the modification of the mesoporous carbon FDU-15. Three nanocomposite films of the poly(methyl methacrylate) (PMMA) and modified FDU-15 were prepared by solution polymerization technique. The surface morphology and thermal and mechanical properties of the hybrid materials were evaluated by different methods. X-ray diffraction patterns showed that modified mesoporous FDU-15 had an ordered hexagonal mesostructure. Transmission electron microscopy (TEM) and field emission-scanning electron microscopy images confirmed the presence of large pores and a relatively ordered mesostructure for the functionalized materials. Thermogravimetric analysis data also revealed that the onset of decomposition temperature of the nanocomposites was higher than that of pristine PMMA, shifting toward higher temperatures as the amount of modified-FDU was increased. TEM images showed the well-ordered hexagonal arrays of mesopores FDU-15. Mechanical data indicated the improvement in the tensile strength and modulus with the modified FDU-15 loading. The film containing 1 wt.% of modified FDU-15 had a tensile strength of the order of 42 MPa, relative to the 28 MPa of the pristine PMMA.

  6. Hierarchical Ordered Mesoporous Carbon from Phloroglucinol-Glyoxal and its Application in Capacitive Deionization of Brackish Water

    SciTech Connect

    Dai, Sheng; DePaoli, David W; Kiggans, Jim; Mayes, Richard T; Tsouris, Costas; Mahurin, Shannon Mark

    2010-01-01

    Templated carbon materials have recently received tremendous attention due to energy storage and separations applications. Hierarchical structures are ideal for increased mass-transport throughout the carbon material. A new ordered mesoporous carbon material has been developed using glyoxal which exhibits a hierarchical structure with pore sizes up to 200 nm. The hierarchical structure arises from the cross linking reagent and not from the standard spinodal decomposition of a secondary solvent. The carbon material was studied for potential application as a capacitive deionization (CDI) electrode for brackish water. Results indicate that the hierarchical structure provides a pathway for faster adsorption kinetics when compared to standard resorcinol-formaldehyde CDI electrodes.

  7. Synthesis, characterization, and electrochemical properties of ordered mesoporous carbons containing nickel oxide nanoparticles using sucrose and nickel acetate in a silica template

    SciTech Connect

    Cao Yulin; Cao Jieming Zheng Mingbo; Liu Jinsong; Ji Guangbin

    2007-02-15

    New ordered mesoporous carbons containing nickel oxide nanoparticles have been successfully synthesized by carbonization of sucrose in the presence of nickel acetate inside SBA-15 mesoporous silica template. The obtained samples were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, and transmission electron microscopy (TEM). The NiO nanoparticles were embedded inside the mesoporous carbon framework due to the simultaneous pyrolysis of nickel acetate during carbonization. The electrochemical testing of the as-made nanocomposites showed a large specific capacitance of 230 F g{sup -1} using 2 M KOH as the electrolyte at room temperature. This is attributed to the nanometer-sized NiO formed inside mesoporous carbons and the high surface area of the mesopores in which the NiO nanoparticles are formed. Furthermore, the synthetic process is proposed as a simple and general method for the preparation of new functionalized mesoporous carbon materials, for various applications in catalysis, sensor or advanced electrode material. - Graphical abstract: Schematic drawings of synthesis routes for the NiOCMK materials.

  8. Egg-Box Structure in Cobalt Alginate: A New Approach to Multifunctional Hierarchical Mesoporous N-Doped Carbon Nanofibers for Efficient Catalysis and Energy Storage

    PubMed Central

    2015-01-01

    Carbon nanomaterials with both doped heteroatom and porous structure represent a new class of carbon nanostructures for boosting electrochemical application, particularly sustainable electrochemical energy conversion and storage applications. We herein demonstrate a unique large-scale sustainable biomass conversion strategy for the synthesis of earth-abundant multifunctional carbon nanomaterials with well-defined doped heteroatom level and multimodal pores through pyrolyzing electrospinning renewable natural alginate. The key part for our chemical synthesis is that we found that the egg-box structure in cobalt alginate nanofiber can offer new opportunity to create large mesopores (∼10–40 nm) on the surface of nitrogen-doped carbon nanofibers. The as-prepared hierarchical carbon nanofibers with three-dimensional pathway for electron and ion transport are conceptually new as high-performance multifunctional electrochemical materials for boosting the performance of oxygen reduction reaction (ORR), lithium ion batteries (LIBs), and supercapacitors (SCs). In particular, they show amazingly the same ORR activity as commercial Pt/C catalyst and much better long-term stability and methanol tolerance for ORR than Pt/C via a four-electron pathway in alkaline electrolyte. They also exhibit a large reversible capacity of 625 mAh g–1 at 1 A g–1, good rate capability, and excellent cycling performance for LIBs, making them among the best in all the reported carbon nanomaterials. They also represent highly efficient carbon nanomaterials for SCs with excellent capacitive behavior of 197 F g–1 at 1 A g–1 and superior stability. The present work highlights the importance of biomass-derived multifunctional mesoporous carbon nanomaterials in enhancing electrochemical catalysis and energy storage. PMID:27162980

  9. Activated carbon from biomass

    NASA Astrophysics Data System (ADS)

    Manocha, S.; Manocha, L. M.; Joshi, Parth; Patel, Bhavesh; Dangi, Gaurav; Verma, Narendra

    2013-06-01

    Activated carbon are unique and versatile adsorbents having extended surface area, micro porous structure, universal adsorption effect, high adsorption capacity and high degree of surface reactivity. Activated carbons are synthesized from variety of materials. Most commonly used on a commercial scale are cellulosic based precursors such as peat, coal, lignite wood and coconut shell. Variation occurs in precursors in terms of structure and carbon content. Coir having very low bulk density and porous structure is found to be one of the valuable raw materials for the production of highly porous activated carbon and other important factor is its high carbon content. Exploration of good low cost and non conventional adsorbent may contribute to the sustainability of the environment and offer promising benefits for the commercial purpose in future. Carbonization of biomass was carried out in a horizontal muffle furnace. Both carbonization and activation were performed in inert nitrogen atmosphere in one step to enhance the surface area and to develop interconnecting porosity. The types of biomass as well as the activation conditions determine the properties and the yield of activated carbon. Activated carbon produced from biomass is cost effective as it is easily available as a waste biomass. Activated carbon produced by combination of chemical and physical activation has higher surface area of 2442 m2/gm compared to that produced by physical activation (1365 m2/gm).

  10. Electrochemical immunosensor based on hydrophilic polydopamine-coated prussian blue-mesoporous carbon for the rapid screening of 3-bromobiphenyl.

    PubMed

    Sun, Zihong; Luo, Zhigang; Gan, Cuifen; Fei, Shidong; Liu, Yingju; Lei, Hongtao

    2014-09-15

    A sensitive electrochemical immunosensor for 3-bromobiphenyl (3-BBP) detection was constructed by employing a new polydopamine coated prussian blue-mesoporous carbon (PDOP/PB/CMK-3) nanocomposite as the substrate platform and multi-horseradish peroxidase-double helix carbon nanotubes-secondary antibody (multi-HRP-DHCNTs-Ab2) as the signal label. PB/CMK-3 was firstly successfully in-situ synthesized with the aid of the CMK-3 reduction, which was characterized by transmission electron microscope (TEM), infrared spectroscopy (IR), X-ray diffraction (XRD) and N2 adsorption-desorption analysis. By using PDOP/PB/CMK-3 as the substrate, it can effectively enhance the specific surface for antigen loading due to the three-dimensional structure of the nanocomposites, while large amount of PB that fixed inside or outside the pore of CMK-3 successfully improved the electrochemical response and the PDOP film can provide a biocompatible environment to maintain the activity of antigen availability. Under the optimized conditions, the proposed immunosensor shows a good current response to 3-BBP in a linear range from 5 pM to 2 nM with a detection limit of 2.25 pM. In addition, the specificity, reproducibility and stability of the immunosensor were also proved to be acceptable, indicating its potential application in environmental monitoring. PMID:24709325

  11. Adsorption kinetics of NO on ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC)

    NASA Astrophysics Data System (ADS)

    Chen, Jinghuan; Cao, Feifei; Chen, Songze; Ni, Mingjiang; Gao, Xiang; Cen, Kefa

    2014-10-01

    Ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC) were prepared using evaporation-induced self-assembly (EISA) method and used to adsorb NO. N2 sorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to confirm their structures. The results showed that the ordered and uniform structures were successfully synthesized and with the introduction of cerium pore properties were not significantly changed. The NO adsorption capacity of OMC was two times larger than that of activated carbon (AC). With the introduction of cerium both the adsorption capacity and the adsorption rate were improved. The effects of residence time and oxygen concentration on NO adsorption were also investigated. Oxygen played an important role in the NO adsorption (especially in the form of chemisorption) and residence time had small influence on the NO adsorption capacity. The NO adsorption kinetics was analyzed using pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion models. The results indicated that the NO adsorption process can be divided into rapid adsorption period, slow adsorption period, and equilibrium adsorption period. The pseudo-second-order model was the most suitable model for NO adsorption on OMC and Ce-OMC. The rate controlling step was the intraparticle diffusion together with the adsorption reaction.

  12. Graphene and carbon nanodots in mesoporous materials: an interactive platform for functional applications

    NASA Astrophysics Data System (ADS)

    Innocenzi, Plinio; Malfatti, Luca; Carboni, Davide

    2015-07-01

    The present review is focused on a specific class of nanocomposites obtained through integration of graphene or carbon-based nanomaterials (such as carbon nanodots) with mesoporous inorganic or hybrid materials, obtained via template assisted self-assembly. The task of integrating graphene and carbon nanodots with a self-assembly process is still very challenging and this review shows some of the solutions which have been envisaged so far. These nanocomposite materials are an ideal interactive platform for developing innovative functional applications; they have a high capability of undergoing integration into advanced devices, which well exploits the advantage of tuning the wide properties and flexibility of the soft-chemistry route. A wide range of applications have been developed so far which span from sensing to electronics up to optics and biomedicine. Even though a large number of proof-of-concepts have been reported to date, an even greater expansion of applications in the field is expected to happen in the near future.

  13. Efficient optical resolution of amino acid by alanine racemaze chiral analogue supported on mesoporous carbon

    NASA Astrophysics Data System (ADS)

    Jang, D.; Kim, K.; Park, D.; Kim, G.

    2012-09-01

    Optically pure D-amino acids are industrially important chiral building blocks for the synthesis of pharmaceuticals, food ingredients, and drug intermediates. Chemoenzymatic dynamic kinetic-resolution processes have recently been developed for deracemization of amino acids. S-ARCA would be a good candidate for the selective adsorption of D amino acid through the imine formation reaction. The organic phase containing S-ARCA adsorbent, TPPC or Ionic Liquid (as a phase transfer catalyst) in MC were coated on the surfaces of mesoporous carbon C-SBA-15(CMK). The aqueous solution of racemic D/L-amino acid and NaOH were added to the carbon support coated with ARCA. The D/L ratios on ARCA and in solution were determined with increasing reaction time. S-ARCA has a unique property for the selective adsorption of D- amino acid (up to 90% selcetivity) in the racemic mixture. The fixed bed reactor containing ARCA/carbon support was also adopted successfully for the selective separation of amino acid.

  14. Synthesis of mesoporous carbon nanoparticles with large and tunable pore sizes.

    PubMed

    Liu, Chao; Yu, Meihua; Li, Yang; Li, Jiansheng; Wang, Jing; Yu, Chengzhong; Wang, Lianjun

    2015-07-21

    Mesoporous carbon nanoparticles (MCNs) with large and adjustable pores have been synthesized by using poly(ethylene oxide)-b-polystyrene (PEO-b-PS) as a template and resorcinol-formaldehyde (RF) as a carbon precursor. The resulting MCNs possess small diameters (100-126 nm) and high BET surface areas (up to 646 m(2) g(-1)). By using home-designed block copolymers, the pore size of MCNs can be tuned in the range of 13-32 nm. Importantly, the pore size of 32 nm is the largest among the MCNs prepared by the soft-templating route. The formation mechanism and structure evolution of MCNs were studied by TEM and DLS measurements, based on which a soft-templating/sphere packing mechanism was proposed. Because of the large pores and small particle sizes, the resulting MCNs were excellent nano-carriers to deliver biomolecules into cancer cells. MCNs were further demonstrated with negligible toxicity. It is anticipated that this carbon material with large pores and small particle sizes may have excellent potential in drug/gene delivery. PMID:26087279

  15. G-quadruplex functionalized nano mesoporous silica for assay of the DNA methyltransferase activity.

    PubMed

    Liu, Pei; Pang, Junling; Yin, Huanshun; Ai, Shiyun

    2015-06-16

    The abnormal level of DNA methyltransferase (MTase) may cause the aberrant DNA methylation, which has been found being associated with a growing number of human diseases, so it is necessary to create a sensitive and selective method to detect DNA MTase activity. In this paper, a new type of DNA functionalized nano mesoporous silica (MSNs) was creatively introduced to the detection of DNA MTase activity with G-quadruplex as a lock for signal molecule to release. The method was carried out by designing a particular DNA which could fold into G-quadruplex and complement with probe DNA. Next, MSNs was prepared before blocking methylene blue (MB) by G-quadruplex. Probe DNA was then fixed on gold nanoparticles modified glass carbon electrode, and the material was able to be transferred to the surface of electrode by DNA hybridization. After methylation of DNA MTase and the cutting of restriction endonuclease, the electrode was transferred to phosphate buffer solution (pH 9.0) for the releasing of MB. The response of differential pulse voltammetry was obtained from the release of MB. Consequently, the difference of signals with or without methylation could prove the assay of M. SssI MTase activity. The results showed that the responses from MB increased linearly with the increasing of the M. SssI MTase concentrations from 0.28 to 50UmL(-1). The limit of detection was 0.28UmL(-1). In addition, Zebularine, a nucleoside analog of cytidine, was utilized for studying the inhibition activity of M. SssI MTase. PMID:26002474

  16. Ultrafine ferroferric oxide nanoparticles embedded into mesoporous carbon nanotubes for lithium ion batteries

    PubMed Central

    Gao, Guo; Zhang, Qiang; Cheng, Xin-Bing; Shapter, Joseph G.; Yin, Ting; Sun, Rongjin; Cui, Daxiang

    2015-01-01

    An effective one-pot hydrothermal method for in situ filling of multi-wall carbon nanotubes (CNT, diameter of 20–40 nm, length of 30–100 μm) with ultrafine ferroferric oxide (Fe3O4) nanoparticles (8–10 nm) has been demonstrated. The synthesized Fe3O4@CNT exhibited a mesoporous texture with a specific surface area of 109.4 m2 g−1. The loading of CNT, in terms of the weight ratio of Fe3O4 nanoparticles, can reach as high as 66.5 wt%. Compared to the conventional method of using a Al2O3 membrane as template to fill CNT with iron oxides nanoparticles, our strategy is facile, effective, low cost and easy to scale up to large scale production (~1.42 g per one-pot). When evaluated for lithium storage at 1.0 C (1 C = 928 mA g−1), the mesoporous Fe3O4@CNT can retain at 358.9 mAh g−1 after 60 cycles. Even when cycled at high rate of 20 C, high capacity of 275.2 mAh g−1 could still be achieved. At high rate (10 C) and long life cycling (500 cycles), the cells still exhibit a good capacity of 137.5 mAhg−1. PMID:26631536

  17. Diffusion-Controlled Drug Release From the Mesoporous Magnesium Carbonate Upsalite(®).

    PubMed

    Zhang, Peng; Zardán Gómez de la Torre, Teresa; Forsgren, Johan; Bergström, Christel A S; Strømme, Maria

    2016-02-01

    In vitro drug release from well-defined particle-size fractions of the mesoporous magnesium carbonate material Upsalite(®) was investigated in detail using ibuprofen, a biopharmaceutics classification system class II drug, as the model compound. The weight of loaded drug corresponded to 30% of the weight of the carrier and the pores were filled to approximately 80%. The incorporated ibuprofen was found to be in an amorphous state and was physisorbed, rather than chemisorbed, to the surfaces of the pore walls. In contrast to ibuprofen in mesoporous silica, there was no detectable drug on the outer surface of the carrier particles. Two ibuprofen doses were loaded into Upsalite(®) particles with size fractions ranging from 25 μm to more than 200 μm. The initial release rate was controlled by the particle size; the dissolution rate of the loaded ibuprofen during this period was more than four times faster than that of the crystalline drug. An extended-release period of about 24 h followed the initial rapid-release period. The features of this extended-release period were dependent on the total drug concentration in the release medium. Detailed analysis of the diffusion of ibuprofen in Upsalite(®) provided the ibuprofen diffusion coefficient (9.8 × 10(-8) cm(2)/s), the constrictivity of the diffusion process (0.47) and the tortuosity of the carrier (15). This relatively high tortuosity value indicates that Upsalite(®) can be used not only to enhance the dissolution rate of poorly soluble drugs but also as a carrier in sustained-release applications by using larger particle sizes or even pellets of the material. PMID:26087956

  18. Preparation and drug release behavior of temperature-responsive mesoporous carbons

    SciTech Connect

    Wang Xiufang; Liu Ping; Tian Yong

    2011-06-15

    A temperature-responsive composite based on poly (N-isopropylacrylamide) (PNIPAAm) and ordered mesoporous carbons (OMCs) has been successfully prepared by a simple wetness impregnation technique. The structures and properties of the composite were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), N{sub 2} sorption, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The results showed that the inclusion of PNIPAAm had not greatly changed the basic ordered pore structure of the OMCs. Ibuprofen (IBU) was selected as model drug, and in vitro test of IBU release exhibited a temperature-responsive controlled release delivery. - Graphical abstract: The bands located at 1650 and 1549 cm{sup -1} could be assigned to C=O stretching and N-H bending vibrations for polymer PNIPAAm (a). The bands at 1388 and 1369 cm{sup -1} were due to isopropyl group, and the band at 1459 cm{sup -1} was related to the bending vibration of C-H (a). For the PNIPAAm/OMCs composite, the characteristic bands of polymer were still observed besides those for carbon materials and the bands at around 1585 cm{sup -1} and a broad band at about 1100 cm{sup -1} were characteristics for the carbon materials(c). In addition, little shifts of C=O and N-H bands compared to the pure PNIPAAm were also observed (b), indicating a weak interaction between the polymer and carbon material. These results could be a proof that the PNIPAAm has been incorporated into the carbon material. Highlights: > A temperature-responsive PNIPAAm/OMCs composite was successfully synthesized by a simple wetness impregnation technique for the first time. > The inclusion of PNIPAAm had not greatly changed the basic ordered pore structure of the OMCs. > In vitro test of IBU release exhibited a temperature-responsive controlled release delivery.

  19. Sulfur-infiltrated micro- and mesoporous silicon carbide-derived carbon cathode for high-performance lithium sulfur batteries.

    PubMed

    Lee, Jung Tae; Zhao, Youyang; Thieme, Sören; Kim, Hyea; Oschatz, Martin; Borchardt, Lars; Magasinski, Alexandre; Cho, Won-Il; Kaskel, Stefan; Yushin, Gleb

    2013-09-01

    Novel nanostructured sulfur (S)-carbide derived carbon (CDC) composites with ordered mesopores and high S content are successfully prepared for lithium sulfur batteries. The tunable pore-size distribution and high pore volume of CDC allow for an excellent electrochemical performance of the composites at high current densities. A higher electrolyte molarity is found to enhance the capacity utilization dramatically and reduce S dissolution in S-CDC composite cathodes during cycling. PMID:23813659

  20. A highly efficient colorimetric immunoassay using a nanocomposite entrapping magnetic and platinum nanoparticles in ordered mesoporous carbon.

    PubMed

    Kim, Moon Il; Ye, Youngjin; Woo, Min-Ah; Lee, Jinwoo; Park, Hyun Gyu

    2014-01-01

    Nanocomposite to achieve ultrafast immunoassay: a new synergistically integrated nanocomposite consisting of magnetic and platinum nanoparticles, simultaneously entrapped in mesoporous carbon, is developed as a promising enzyme mimetic candidate to achieve ultrafast colorimetric immunoassays. Using new assay system, clinically important target molecules, such as human epidermal growth factor receptor 2 (HER2) and diarrhea-causing rotavirus, can be detected in only 3 min at room temperature with high specificity and sensitivity. PMID:23832855

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

    SciTech Connect

    Atchudan, R.; Joo, Jin.; Pandurangan, A.

    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-CNTs 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.

  2. Catalytic reduction-adsorption for removal of p-nitrophenol and its conversion p-aminophenol from water by gold nanoparticles supported on oxidized mesoporous carbon.

    PubMed

    Guo, Pucan; Tang, Lin; Tang, Jing; Zeng, Guangming; Huang, Binbin; Dong, Haoran; Zhang, Yi; Zhou, Yaoyu; Deng, Yaocheng; Ma, Linlin; Tan, Shiru

    2016-05-01

    A highly efficient method for removal of p-nitrophenol and its conversion p-aminophenol from water was proposed using a novel catalyst-adsorbent composite of gold nanoparticles supported on functionalized mesoporous carbon (Au@CMK-3-O). The immobilized gold nanoparticles presented excellent catalytic ability to converse p-nitrophenol into p-aminophenol with the help of sodium borohydride, and the oxidized mesoporous carbon (CMK-3-O) serving as both carrier and adsorbent also exhibited high efficiency to remove p-aminophenol. The morphology and structure of the composite were characterized via SEM, TEM, FTIR and XPS analysis. Moreover, the mechanism of reaction process and the parameters of kinetics and thermodynamics were investigated. The activation energy was figured as 86.8kJmol(-1) for the adsorption and reduction of p-nitrophenol to p-aminophenol. The thermodynamic analysis based on the rate constants evaluated by pseudo-first-order model reveals that the adsorption-reduction process is an endothermic procedure with the rise of randomness. The anti-oxidation and regeneration study indicates that Au@CMK-3-O can be reused for 6 times with more than 90% conversion efficiency and keep high activity after exposing in air for 1month, which possesses great prospects in application of nitroaromatic pollutant removal. PMID:26871277

  3. Facile Synthesis of Nitrogen-Containing Mesoporous Carbon for High-Performance Energy Storage Applications.

    PubMed

    Xu, Yunling; Wang, Jie; Chang, Zhi; Ding, Bing; Wang, Ya; Shen, Laifa; Mi, Changhuan; Dou, Hui; Zhang, Xiaogang

    2016-03-14

    Porous carbon with high specific surface area (SSA), a reasonable pore size distribution, and modified surface chemistry is highly desirable for application in energy storage devices. Herein, we report the synthesis of nitrogen-containing mesoporous carbon with high SSA (1390 m(2)  g(-1) ), a suitable pore size distribution (1.5-8.1 nm), and a nitrogen content of 4.7 wt % through a facile one-step self-assembly process. Owing to its unique physical characteristics and nitrogen doping, this material demonstrates great promise for application in both supercapacitors and encapsulating sulfur as a superior cathode material for lithium-sulfur batteries. When deployed as a supercapacitor electrode, it exhibited a high specific capacitance of 238.4 F g(-1) at 1 A g(-1) and an excellent rate capability (180 F g(-1) , 10 A g(-1) ). Furthermore, when an NMC/S electrode was evaluated as the cathode material for lithium-sulfur batteries, it showed a high initial discharge capacity of 1143.6 mA h g(-1) at 837.5 mA g(-1) and an extraordinary cycling stability with 70.3 % capacity retention after 100 cycles. PMID:26849174

  4. Mesoporous carbon spheres with controlled porosity for high-performance lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Wang, Dexian; Fu, Aiping; Li, Hongliang; Wang, Yiqian; Guo, Peizhi; Liu, Jingquan; Zhao, Xiu Song

    2015-07-01

    Mesoporous carbon (MC) spheres with hierarchical pores, controlled pore volume and high specific surface areas have been prepared by a mass-producible spray drying assisted template method using sodium alginate as carbon precursor and commercial colloidal silica particles as hard template. The resulting MC spheres, possessing hierarchical pores in the range of 3-30 nm, are employed as conductive matrices for the preparation of cathode materials for lithium-sulfur batteries. A high pressure induced one-step impregnation of elemental sulfur into the pore of the MC spheres has been exploited. The electrochemical performances of sulfur-impregnated MC spheres (S-MC) derived from MC spheres with different pore volume and specific surface area but with the same sulfur loading ratio of 60 wt% (S-MC-X-60) have been investigated in details. The S-MC-4-60 composite cathode material displayed a high initial discharge capacity of 1388 mAhg-1 and a good cycling stability of 857 mAhg-1 after 100 cycles at 0.2C, and shows also excellent rate capability of 864 mAhg-1 at 2C. More importantly, the sulfur loading content in MC-4 spheres can reach as high as 80%, and it still can deliver a capacity of 569 mAhg-1 after 100 cycles at 0.2C.

  5. Synthesis of magnetic ordered mesoporous carbon (Fe-OMC) adsorbent and its evaluation for fuel desulfurization

    NASA Astrophysics Data System (ADS)

    Farzin Nejad, N.; Shams, E.; Amini, M. K.

    2015-09-01

    In this work, magnetic ordered mesoporous carbon adsorbent was synthesized using soft templating method to adsorb sulfur from model oil (dibenzothiophene in n-hexane). Through this research, pluronic F-127, resorcinol-formaldehyde and hydrated iron nitrate were respectively used as soft template, carbon source and iron source. The adsorbent was characterized by X-ray diffraction, nitrogen adsorption-desorption isotherm and transmission electron microscopy. Nitrogen adsorption-desorption measurement revealed the high surface area (810 m2 g-1), maxima pore size of 3.3 nm and large pore volume (1.01 cm3 g-1) of the synthesized sample. The adsorbent showed a maximum adsorption capacity of 111 mg dibenzothiophene g-1 of adsorbent. Sorption process was described by the pseudo-second-order rate equation and could be better fitted by the Freundlich model, showing the heterogeneous feature of the adsorption process. In addition, the adsorption capacity of regenerated adsorbent was 78.6% of the initial level, after five regeneration cycles.

  6. Advances in Pd Nanoparticle Size Decoration of Mesoporous Carbon Spheres for Energy Application

    NASA Astrophysics Data System (ADS)

    Zielinska, Beata; Michalkiewicz, Beata; Mijowska, Ewa; Kalenczuk, Ryszard Jzef

    2015-10-01

    Pd nanoparticles with different sizes and diameter distributions were successfully deposited on the surface of disordered mesoporous carbon spheres (DMHCS). The size and diameter distribution of the Pd particles were controlled by the application of different experimental conditions. Two methods of synthesis (reflux and impregnation) and two Pd precursors (palladium (II) acetyloacetonate (Pd (acac ) 2) and palladium (II) acetate (Pd(OAc)2)) were investigated and compared for the preparation of Pd-decorated DMHCS. The hydrogen storage properties of the pristine DMHCS and Pd-modified DMHCS at 40 C and a pressure range of 0-45 bar were studied. The results showed that Pd-supported carbon samples synthesized in the presence of Pd(OAc)2 exhibited enhanced hydrogen storage capacity in respect to the pristine DMHCS. The maximum hydrogen storage of 0.38 wt.% exhibited the sample with the Pd nanoparticle diameter distribution of 2-14 nm and the average Pd crystallite size of 7.6 nm. It was found that the Pd nanoparticle content, size, and diameter distribution have a noticeable influence on H2 storage capacity.

  7. Adsorption behavior and mechanisms of ciprofloxacin from aqueous solution by ordered mesoporous carbon and bamboo-based carbon.

    PubMed

    Peng, Xiaoming; Hu, Fengping; Lam, Frank L-Y; Wang, Yajun; Liu, Zhanmeng; Dai, Hongling

    2015-12-15

    The performances of ordered mesoporous carbon CMK-3 (OMC), bamboo-based carbon (BC), and these two kinds of adsorbents modified by thermal treatment in the ammonia atmosphere at high temperatures were evaluated for the removal fluoroquinolone antibiotic (ciprofloxacin) from aqueous solution. The adsorption behavior of ciprofloxacin (CIP) onto OMC and BC including adsorption isotherms and kinetics were investigated. The effect of various factors (pH, ionic strength and temperature) on the adsorption process was also investigated. The results demonstrated that the modified OMC and BC can further enhance the adsorption capacity due to introduce of alkaline nitrogen functionalities on the carbon surface. And their maximum adsorption capacity reached as high as 233.37mgg(-1) and 362.94mgg(-1) under the same experimental conditions, respectively. This is primarily ascribed to the positive effect of the surface basicity. The highest sorption was observed at the lowest solubility, which indicated that hydrophobic interaction was the dominant sorption mechanism for CIP uptake onto the four adsorbents. The adsorption data of antibiotics was analyzed by Langmuir and Freundlich model, and the better correlation was achieved by the Langmuir isotherm. The kinetic data showed that the adsorption of CIP onto OMC and BC follow closely the pseudo-second order model. The removal efficiency and adsorption capacity increased with increasing temperature. The results of thermodynamic study indicated that the adsorption process was a spontaneous and endothermic. PMID:26385593

  8. SBA-15 Mesoporous Silica Modified with Gallic Acid and Evaluation of Its Cytotoxic Activity

    PubMed Central

    Lewandowski, Dawid

    2015-01-01

    Gallic acid has been covalently conjugated to SBA-15 mesoporous silica surface through different linkers. Cytotoxic activity of the hybrid organic-inorganic systems against HeLa and KB cell lines has been analyzed. Up to 67% of HeLa or KB tumor cells growth inhibition has been achieved at low silica concentration used (10 μg mL-1). PMID:26151908

  9. Direct tri-constituent co-assembly of highly ordered mesoporous carbon counter electrode for dye-sensitized solar cells.

    PubMed

    Peng, Tao; Sun, Weiwei; Sun, Xiaohua; Huang, Niu; Liu, Yumin; Bu, Chenghao; Guo, Shishang; Zhao, Xing-Zhong

    2013-01-01

    Controlling over ordered porosity by self-assembly is challenging in the area of materials science. Materials with highly ordered aperture are favorable candidates in catalysis and energy conversion device. Here we describe a facile process to synthesize highly ordered mesoporous carbon (OMC) by direct tri-constituent co-assembly method, which uses resols as the carbon precursor, tri-block copolymer F127 as the soft template and tetraethoxysilane (TEOS) as the inorganic precursor. The obtained products are characterized by small-angle X-ray diffraction (SAXD), Brunauer-Emmett-Teller (BET) nitrogen sorption-desorption measurement and transmission electron microscope (TEM). The results indicate that the OMC possesses high surface areas of 1209 m(2) g(-1), homogeneous pore size of 4.6 nm and a large pore volume of 1.65 cm(3) g(-1). The advantages of high electrochemical active surface area and favorable accessible porosity of OMC benefit the catalysis of I(3)(-) to I(-). As a result, the OMC counter electrode displays a remarkable property when it was applied in dye-sensitized solar cells (DSSCs). For comparison, carbon black (CB) counter electrode and Pt counter electrode have also been prepared. When these different counter electrodes were applied for dye-sensitized solar cells (DSSCs), the power-conversion efficiency (η) of the DSSCs with CB counter electrode are measured to be 5.10%, whereas the corresponding values is 6.39% for the DSSC with OMC counter electrode, which is comparable to 6.84% of the cell with Pt counter electrode under the same experimental conditions. PMID:23165970

  10. Bimetallic cerium-copper nanoparticles embedded in ordered mesoporous carbons as effective catalysts for the selective catalytic reduction of NO with NH₃.

    PubMed

    Chen, Jinghuan; Cao, Feifei; Qu, Ruiyang; Gao, Xiang; Cen, Kefa

    2015-10-15

    Bimetallic cerium-copper nanoparticles embedded in ordered mesoporous carbons (OMCs) with various Ce/Cu ratios were synthesized by "one-pot" self-assembly method, and their activities for the selective catalytic reduction (SCR) of NO with ammonia were studied. The structural and textural properties, surface chemistry, acidity, and reducibility were investigated by various techniques. Results showed that NO conversion was greatly influenced by the weight ratio of Ce to Cu. An appropriate Ce/Cu ratio in OMCs could enhance catalytic performance; the optimal catalytic performance was obtained with Ce5Cu5-OMC. Ordered mesoporous structures were formed for all synthesized samples. When Ce or Cu was incorporated into the OMCs, the amount of surface acidic oxygen functional groups increased, thereby promoting the acidic properties of the OMCs, especially those of the Cu-rich OMCs. The surface Cu(2+) species may accelerate ammonia activation and may play an important role in SCR reaction. The temperature-programmed reduction results illustrated that the Cu-rich OMCs had better reducibility, and the appropriate Ce/Cu ratio could further enhance the redox ability of the CexCuy-OMC catalysts. The existing redox cycle (Ce(4+)+Cu(+)↔Cu(2+)+Ce(3+)) promoted the activation of NH3 and consequently improved NH3-SCR activity. PMID:26093235

  11. Label free detection of lead using impedimetric sensor based on ordered mesoporous carbon-gold nanoparticles and DNAzyme catalytic beacons.

    PubMed

    Zhou, Yaoyu; Tang, Lin; Zeng, Guangming; Zhang, Chen; Xie, Xia; Liu, Yuanyuan; Wang, Jiajia; Tang, Jing; Zhang, Yi; Deng, Yaocheng

    2016-01-01

    A novel label-free impedimetric sensing system based on DNAzyme and ordered mesoporous carbon-gold nanoparticle (OMC-GNPs) for the determination of Pb(2+) concentration was developed in the present study. Firstly, gold nanoparticles deposited on the modified electrode surface were employed as a platform for the immobilization of thiolated probe DNA, and then hybridized with DNAzyme catalytic beacons. Subsequently, in the presence of Pb(2+), the DNAzyme could be activated to cleave the substrate strand into two DNA fragments, which causes differences in the electrical properties of the film. Randles equivalent circuit was employed to evaluate the electrochemical impedance spectroscopy (EIS) result. The charge transfer resistance (R(CT)) value for the [Fe(CN)6](3-/4-) redox indicator was remarkably decline after hybridization with Pb(2+). The difference in RCT values before and after hybridization with Pb(2+) showed a linear relation with the concentration of the Pb(2+) in a range of 5×10(-10)-5×10(-5) M, with a detection limit of 2×10(-10) M (S/N=3). Furthermore, with the application of Pb(2+) dependent 8-17DNAzyme, the proposed sensing system exhibited high selectivity without using any labeled probes. This biosensor demonstrated a promising potential for Pb(2+) detection in real sample. PMID:26695312

  12. Mesoporous Hybrid Shells of Carbonized Polyaniline/Mn2O3 as Non-Precious Efficient Oxygen Reduction Reaction Catalyst.

    PubMed

    Cao, Shiyi; Han, Na; Han, Jie; Hu, Yimin; Fan, Lei; Zhou, Chuanqiang; Guo, Rong

    2016-03-01

    Mesoporous hybrid shells of carbonized polyaniline (CPANI)/Mn2O3 with well-controlled diameter and high surface area have been synthesized through surface protected calcination processes. Originating from polystyrene template, PANI, MnO2, and SiO2 were sequentially loaded, followed by template removal and calcination, resulting in the desired CPANI/Mn2O3 hybrid shells. The introduction of SiO2 shell was established to play the determining role in maintaining the configuration during calcination process under high temperature. The CPANI/Mn2O3 hybrid shells showed outstanding electrocatalytic activity toward oxygen reduction reaction (ORR), with the onset potential at +0.974 V (versus RHE), the specific current at 60.8 mA/mg, and an overall quasi 4-electron transfer, which are comparable to those of the benchmark Pt/C. The remarkable ORR performance was attributed to the high specific surface area, the surface oxidation state of Mn, and composition-codependent behavior. PMID:26881985

  13. Platinum particles supported on mesoporous carbons: fabrication and electrocatalytic performance in methanol-tolerant oxygen-reduction reactions

    PubMed Central

    Dong, Cheng-Di; Chen, Chiu-Wen; Chen, Chih-Feng; Hung, Chang-Mao

    2014-01-01

    In this report, we describe the preparation and electrochemical characterization of a Pt electrocatalyst, which was synthesized from hexachloroplatinic acid, using the incipient wetness impregnation method. This carbon mesoporous materials (Pt-CMMs) electrocatalyst was used for catalyzing the oxidation of methanol and its oxygen-reduction reaction. The electrocatalytic oxidation of methanol was studied using linear-sweep voltammograms (LSV), polarization and chronoamperometric measurements. Phase characterizations and morphological analyses were performed using 3D excitation-emission fluorescent matrix (EEFM) spectroscopy, UV-Vis absorption measurements, and X-ray diffraction (XRD) and environmental scanning electron microscopy (ESEM) techniques; the ESEM system was equipped with an energy-dispersive spectrometer (EDS). The oxidation capacity measured using a LSV might explain the high activity exhibited by the Pt-CMM electrocatalysts in methanol-tolerant oxygen reduction, and the results demonstrated that the potential and current density of the main reaction peak of the Pt-CMMs electrocatalyst changed during the reaction. Moreover, EEFM spectroscopy and XRD were determined to be appropriate and effective methods for characterizing Pt clusters that enhance their intrinsic emission from Pt-CMMs electrocatalysts in electrocatalytic-treatment systems. Furthermore, the ESEM-EDS results showed that fresh Pt nanoparticles were highly dispersed on CMMs and featured a 20 nm diameter and a narrow particle-size distribution. PMID:25168212

  14. Platinum particles supported on mesoporous carbons: fabrication and electrocatalytic performance in methanol-tolerant oxygen-reduction reactions

    NASA Astrophysics Data System (ADS)

    Dong, Cheng-Di; Chen, Chiu-Wen; Chen, Chih-Feng; Hung, Chang-Mao

    2014-08-01

    In this report, we describe the preparation and electrochemical characterization of a Pt electrocatalyst, which was synthesized from hexachloroplatinic acid, using the incipient wetness impregnation method. This carbon mesoporous materials (Pt-CMMs) electrocatalyst was used for catalyzing the oxidation of methanol and its oxygen-reduction reaction. The electrocatalytic oxidation of methanol was studied using linear-sweep voltammograms (LSV), polarization and chronoamperometric measurements. Phase characterizations and morphological analyses were performed using 3D excitation-emission fluorescent matrix (EEFM) spectroscopy, UV-Vis absorption measurements, and X-ray diffraction (XRD) and environmental scanning electron microscopy (ESEM) techniques; the ESEM system was equipped with an energy-dispersive spectrometer (EDS). The oxidation capacity measured using a LSV might explain the high activity exhibited by the Pt-CMM electrocatalysts in methanol-tolerant oxygen reduction, and the results demonstrated that the potential and current density of the main reaction peak of the Pt-CMMs electrocatalyst changed during the reaction. Moreover, EEFM spectroscopy and XRD were determined to be appropriate and effective methods for characterizing Pt clusters that enhance their intrinsic emission from Pt-CMMs electrocatalysts in electrocatalytic-treatment systems. Furthermore, the ESEM-EDS results showed that fresh Pt nanoparticles were highly dispersed on CMMs and featured a 20 nm diameter and a narrow particle-size distribution.

  15. Platinum particles supported on mesoporous carbons: fabrication and electrocatalytic performance in methanol-tolerant oxygen-reduction reactions.

    PubMed

    Dong, Cheng-Di; Chen, Chiu-Wen; Chen, Chih-Feng; Hung, Chang-Mao

    2014-01-01

    In this report, we describe the preparation and electrochemical characterization of a Pt electrocatalyst, which was synthesized from hexachloroplatinic acid, using the incipient wetness impregnation method. This carbon mesoporous materials (Pt-CMMs) electrocatalyst was used for catalyzing the oxidation of methanol and its oxygen-reduction reaction. The electrocatalytic oxidation of methanol was studied using linear-sweep voltammograms (LSV), polarization and chronoamperometric measurements. Phase characterizations and morphological analyses were performed using 3D excitation-emission fluorescent matrix (EEFM) spectroscopy, UV-Vis absorption measurements, and X-ray diffraction (XRD) and environmental scanning electron microscopy (ESEM) techniques; the ESEM system was equipped with an energy-dispersive spectrometer (EDS). The oxidation capacity measured using a LSV might explain the high activity exhibited by the Pt-CMM electrocatalysts in methanol-tolerant oxygen reduction, and the results demonstrated that the potential and current density of the main reaction peak of the Pt-CMMs electrocatalyst changed during the reaction. Moreover, EEFM spectroscopy and XRD were determined to be appropriate and effective methods for characterizing Pt clusters that enhance their intrinsic emission from Pt-CMMs electrocatalysts in electrocatalytic-treatment systems. Furthermore, the ESEM-EDS results showed that fresh Pt nanoparticles were highly dispersed on CMMs and featured a 20 nm diameter and a narrow particle-size distribution. PMID:25168212

  16. Activated carbon material

    DOEpatents

    Evans, A. Gary

    1978-01-01

    Activated carbon particles for use as iodine trapping material are impregnated with a mixture of selected iodine and potassium compounds to improve the iodine retention properties of the carbon. The I/K ratio is maintained at less than about 1 and the pH is maintained at above about 8.0. The iodine retention of activated carbon previously treated with or coimpregnated with triethylenediamine can also be improved by this technique. Suitable flame retardants can be added to raise the ignition temperature of the carbon to acceptable standards.

  17. Phospholipid-stabilized mesoporous carbon nanospheres as versatile carriers for systemic delivery of amphiphobic SNX-2112 (a Hsp90 inhibitor) with enhanced antitumor effect.

    PubMed

    Zhang, Xingwang; Zhang, Tianpeng; Ye, Yanghuan; Chen, Huaqing; Sun, Hua; Zhou, Xiaotong; Ma, Zhiguo; Wu, Baojian

    2015-08-01

    Systemic delivery of amphiphobic drugs (insoluble in both water and oil) represents a formidable challenge in drug delivery. This work aimed to engineer a functional mesoporous carbon material to efficiently load SNX-2112, an amphiphobic anticancer agent, and to evaluate its performance in tumor-targeting delivery. Hydrothermal reaction combined with high-temperature activation was used to fabricate glucose-based mesoporous carbon nanospheres (MCNs). SNX-2112-loaded MCNs stabilized by phospholipid (SN-PMCNs) were prepared by the absorption/solvent diffusion/high-pressure homogenization method. The obtained SN-PMCNs were 180nm around in particle size, showing a high drug load (42.7%) and acceptable physical stability. SN-PMCNs demonstrated an enhanced in vitro antitumor effect and increased uptake into cancer cells in comparison with the formulation of SNX-2112 solution (SN-Sol). The in vivo antitumor effect and biodistribution in 4T1 xenograft tumor mice, a breast cancer model, were also significantly improved through SN-PMCNs. It was shown that specific clathrin-dependent and nonspecific caveolae-dependent endocytosis were involved in the cellular trafficking of SN-PMCNs. Glucose transporter-mediated transport, prolonged body residence time and improved biodistribution via EPR effect were the main mechanisms of enhanced antitumor effect. SN-PMCNs have presented excellent tumor targeting properties and should be a promising carrier to address the systemic delivery of SNX-2112. PMID:25936860

  18. Fabrication of density-controlled graphene oxide-coated mesoporous silica spheres and their electrorheological activity.

    PubMed

    Yoon, Chang-Min; Lee, Seungae; Hong, Seung Hee; Jang, Jyongsik

    2015-01-15

    A series of density-controlled graphene oxide-coated mesoporous silica spheres (GO/SiO2) are successfully synthesized to investigate the influence of the particle density on electrorheological (ER) activity. The particle density of mesoporous silica spheres is controlled by creating different sized pores via surfactant template and swelling agent incorporation method. Additionally, ball-milled graphene oxide is successfully coated onto the surface of various silica spheres (SiO2) through amine-modification to enhance ER efficiency. In this study, we investigate that mesoporous silica spheres-based ER fluid (GO/epSiO2) with lowest particle density exhibit most increased ER performance, which is 3-fold higher than that of similar sized neat silica spheres-based ER fluid (GO/nSiO2) without pore. In addition, the relationship between particle density, anti-sedimentation property, and ER performance is examined by applying Stokes' law and practical sedimentation observation. Furthermore, dielectric loss model is used to clarify the influence of dielectric property on ER activity. This newly designed ER study offers insight into the influence of the particle density on the performance of ER fluids. PMID:25454420

  19. Controlled Synthesis of N-Doped Carbon Nanospheres with Tailored Mesopores through Self-Assembly of Colloidal Silica.

    PubMed

    Wang, Gang; Sun, Yuhan; Li, Debao; Liang, Hai-Wei; Dong, Renhao; Feng, Xinliang; Müllen, Klaus

    2015-12-01

    Limited strategies have been established to prepare monodisperse mesoporous carbon nanospheres (MCNs) with tailored pore sizes. In this work, a method is reported to synthesize MCNs by combining polymerization of aniline with co-assembly of colloidal silica nanoparticles. The controlled self-assembly behavior of colloidal silica enables the formation of uniform composite nanospheres and convenient modulation over mesopores. After carbonization and removal of sacrificial templates, the resultant MCNs possess tunable mesopores (7-42 nm) and spherical diameters (90-300 nm), as well as high surface area (785-1117 m(2)  g(-1) ), large pore volume (1.46-2.01 cm(3)  g(-1) ) and abundant nitrogen moieties (5.54-8.73 at %). When serving as metal-free electrocatalysts for the oxygen reduction reaction (ORR), MCNs with an optimum pore size of 22 nm, compared to those with 7 and 42 nm, exhibit the best ORR performance in alkaline medium. PMID:26489773

  20. Facile synthesis of yolk-shell magnetic mesoporous carbon microspheres for efficient enrichment of low abundance peptides

    NASA Astrophysics Data System (ADS)

    Wan, Hao; Qin, Hongqiang; Xiong, Zhichao; Zhang, Weibing; Zou, Hanfa

    2013-10-01

    Magnetic mesoporous carbon microspheres with a yolk-shell structure (YSMMCS) have been prepared via a new in situ carbon source strategy. The material was fabricated by two shells coated onto the Fe3O4 particles; the inner dense and thick silica shell could protect the magnetic core from harsh acidic solvents as well as induce the void between the core and the outer shell for the yolk-shell structure, while the outer organosilica shell was used as the template and carbon source for in situ preparation of a carbon shell with mesoporous structure. A C18-alkyl chain was incorporated in situ as the carbon precursor efficiently, avoiding the conventional infiltration step, which was very difficult to manipulate and time-consuming with the possibility of losing the carbon precursor. The resulting yolk-shell magnetic mesoporous carbon microspheres exhibited a high surface area (273.15 m2 g-1), a large pore volume (0.31 cm3 g-1), and a strong magnetic response (a saturation magnetization value of 34.57 emu g-1). As a result of the void between the core and the outer shell and the π-π stacking effect, adsorption capacity reached 191.64 mg g-1 by using Rhodamine B as a standard analyte, indicating the great potential application of the material as drug carriers. Owing to the inherent hydrophobicity and high surface area, the composite material showed better performance in the enrichment of peptides than a magnetic mesoporous silica material (Fe2O3@nSiO2@mSiO2). According to the LC-MS/MS results, about 51 and 29 nonredundant peptides were identified from tryptic digests of 5 nM BSA. Additionally, taking advantage of the mesoporous structure and strong magnetic response, the material was utilized to selectively extract low abundance endogenous peptides from human serum in the presence of high abundance proteins. Based on the LC-MS/MS results, 962 endogenous peptides were obtained by 2.5 mg YSMMCS relative to 539 endogenous peptides by 5 mg Fe2O3@nSiO2@mSiO2, confirming the outstanding performance of YSMMCS in peptidome analysis.Magnetic mesoporous carbon microspheres with a yolk-shell structure (YSMMCS) have been prepared via a new in situ carbon source strategy. The material was fabricated by two shells coated onto the Fe3O4 particles; the inner dense and thick silica shell could protect the magnetic core from harsh acidic solvents as well as induce the void between the core and the outer shell for the yolk-shell structure, while the outer organosilica shell was used as the template and carbon source for in situ preparation of a carbon shell with mesoporous structure. A C18-alkyl chain was incorporated in situ as the carbon precursor efficiently, avoiding the conventional infiltration step, which was very difficult to manipulate and time-consuming with the possibility of losing the carbon precursor. The resulting yolk-shell magnetic mesoporous carbon microspheres exhibited a high surface area (273.15 m2 g-1), a large pore volume (0.31 cm3 g-1), and a strong magnetic response (a saturation magnetization value of 34.57 emu g-1). As a result of the void between the core and the outer shell and the π-π stacking effect, adsorption capacity reached 191.64 mg g-1 by using Rhodamine B as a standard analyte, indicating the great potential application of the material as drug carriers. Owing to the inherent hydrophobicity and high surface area, the composite material showed better performance in the enrichment of peptides than a magnetic mesoporous silica material (Fe2O3@nSiO2@mSiO2). According to the LC-MS/MS results, about 51 and 29 nonredundant peptides were identified from tryptic digests of 5 nM BSA. Additionally, taking advantage of the mesoporous structure and strong magnetic response, the material was utilized to selectively extract low abundance endogenous peptides from human serum in the presence of high abundance proteins. Based on the LC-MS/MS results, 962 endogenous peptides were obtained by 2.5 mg YSMMCS relative to 539 endogenous peptides by 5 mg Fe2O3@nSiO2@mSiO2, confirming the outstanding performance of YSMMCS in peptidome analysis. Electronic supplementary information (ESI) available: See DOI: 10.1039/c3nr02932h

  1. Carbon-Dot-Sensitized, Nitrogen-Doped TiO2 in Mesoporous Silica for Water Decontamination through Nonhydrophobic Enrichment-Degradation Mode.

    PubMed

    Cheng, Chen; Tan, Xianjun; Lu, Deli; Wang, Lingzhi; Sen, Tapas; Lei, Juying; El-Toni, Ahmed Mohamed; Zhang, Jinlong; Zhang, Fan; Zhao, Dongyuan

    2015-12-01

    Mesoporous silica synthesized from the cocondensation of tetraethoxysilane and silylated carbon dots containing an amide group has been adopted as the carrier for the in situ growth of TiO2 through an impregnation-hydrothermal crystallization process. Benefitting from initial complexation between the titania precursor and carbon dot, highly dispersed anatase TiO2 nanoparticles can be formed inside the mesoporous channel. The hybrid material possesses an ordered hexagonal mesostructure with p6mm symmetry, a high specific surface area (446.27 m(2)  g(-1) ), large pore volume (0.57 cm(3)  g(-1) ), uniform pore size (5.11 nm), and a wide absorption band between λ=300 and 550 nm. TiO2 nanocrystals are anchored to the carbon dot through TiON and TiOC bonds, as revealed by X-ray photoelectron spectroscopy. Moreover, the nitrogen doping of TiO2 is also verified by the formation of the TiN bond. This composite shows excellent adsorption capabilities for 2,4-dichlorophenol and acid orange 7, with an electron-deficient aromatic ring, through electron donor-acceptor interactions between the carbon dot and organic compounds instead of the hydrophobic effect, as analyzed by the contact angle analysis. The composite can be photocatalytically recycled through visible-light irradiation after adsorption. The narrowed band gap, as a result of nitrogen doping, and the photosensitization effect of carbon dots are revealed to be coresponsible for the visible-light activity of TiO2 . The adsorption capacity does not suffer any clear losses after being recycled three times. PMID:26487497

  2. Sorption of uranium(VI) using oxime-grafted ordered mesoporous carbon CMK-5.

    PubMed

    Tian, Gan; Geng, Junxia; Jin, Yongdong; Wang, Chunli; Li, Shuqiong; Chen, Zhen; Wang, Hang; Zhao, Yongsheng; Li, Shoujian

    2011-06-15

    A new sorbent for uranium(VI) has been developed by functionalizing ordered mesoporous carbon CMK-5 with 4-acetophenone oxime via thermally initiated diazotization. The sorption of U(VI) ions onto the functionalized CMK-5 (Oxime-CMK-5) was investigated as a function of sorbent dosage, pH value, contact time, ionic strength and temperature using batch sorption techniques. The results showed that U(VI) sorption onto Oxime-CMK-5 was strongly dependent on pH, but to a lesser extent, on ionic strength. Kinetic studies revealed that the sorption process achieved equilibrium within 30 min and followed a pseudo-first-order rate equation. The isothermal data correlated with the Langmuir model better than the Freundlich model. Thermodynamic data indicated the spontaneous and endothermic nature of the process. Under current experimental conditions, a maximum U(VI) sorption capacity was found to be 65.18 mg/g. Quantitative recovery of uranium was achieved by desorbing the U(VI)-loaded Oxime-CMK-5 with 1.0 mol/L HCl and no significant decrease in U(VI) sorption capability of Oxime-CMK-5 was observed after five consecutive sorption-desorption cycles. The sorption study performed in a simulated nuclear industry effluent demonstrated that the new sorbent showed a desirable selectivity for U(VI) ions over a range of competing metal ions. PMID:21497013

  3. Bioresponsive carbon nano-gated multifunctional mesoporous silica for cancer theranostics.

    PubMed

    Prasad, Rajendra; Aiyer, Sandhya; Chauhan, Deepak S; Srivastava, Rohit; Selvaraj, Kaliaperumal

    2016-02-18

    Designing bioresponsive nanocarriers for controlled and efficient intracellular drug release for cancer therapy is a major thrust area in nanomedicine. With recent recognition by the US FDA as a safe material for human trials, mesoporous silica nanoparticles (MSNPs) are being extensively explored as promising theranostic agents. Green fluorescent carbon quantum dots (CQDs), though known as possible alternatives for their more toxic and relatively less efficient predecessors, are less known as gate keepers for drug release control. We report for the first time an efficient bioresponse of CQDs when judiciously designed using glutathione cleavable (redox responsive) disulphide bonds. When the anticancer drug doxorubicin loaded MSNPs are capped with these CQDs, they display promising drug release control on exposure to a mimicked intracellular cancer environment. Their dual functionality is well established with good control on preventing the premature release and exceptional bio-imaging of HeLa cancer cells. Fluorescence images prove selective targeting of HeLa cells by overexpression of folate receptors from the surface functionalised folic acid ligand. Extensive characterisation using XRD, TEM, BET analysis, drug loading tests, drug release kinetics, MTT assay and fluoroscence cell imaging helps in understanding the multifunctionalities of the successful design, extending its scope with exciting prospects towards non-invasive targeted drug delivery and bio-imaging for effective cancer diagnosis and treatment. PMID:26753966

  4. Investigation of Mesoporous Graphitic Carbon Nitride as the Adsorbent to Remove Ni (II) Ions.

    PubMed

    Xin, Gang; Xia, Yuanjiao; Lv, Yuhua; Liu, Luman; Yu, Bei

    2016-04-01

    The mesoporous graphitic carbon nitride (mpg-C3N4/r, r was defined as the initial silica/dicyandiamide mass ratio) was successfully synthesized by heating the mixture of silica and dicyandiamide in a nitrogen atmosphere. The morphology and structure of mpg-C3N4/r were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller surface area measurement (BET), X-ray powder diffraction (XRD), and Fourier Transform Infrared spectroscopy (FT-IR). The adsorption performances of Ni (II) ions by mpg-C3N4/r were investigated. With increasing of r value, the BET specific surface area of the synthesized mpg-C3N4/r increased; the highest specific surface area of mpg-C3N4/1.5 increased up to 169.3 m2/g. This work shows that mpg-C3N4/1.5 is a promising, high-efficiency adsorbent that can be used to purify the water of a low Ni (II) ions concentration. The maximum adsorption capacity of Ni(II) ions by mpg-C3N4/1.5 was 15.26 mg/g. The adsorption properties of Ni (II) ions by mpg-C3N4/r complied well with pseudo-second-order kinetics and Langmuir isotherm model. PMID:27131055

  5. Adsorption behaviors of methyl orange dye on nitrogen-doped mesoporous carbon materials.

    PubMed

    Li, He; An, Nihong; Liu, Gang; Li, Jialu; Liu, Na; Jia, Mingjun; Zhang, Wenxiang; Yuan, Xiaoling

    2016-03-15

    A series of nitrogen-doped mesoporous carbon materials (NMC) with different nitrogen contents (from 9.1 to 11.3wt.%) were prepared using urea and ammonia as economical nitrogen resources by sol-gel method. The NMC materials possessed high surface areas (from 659m(2)/g to 912m(2)/g) as well as large number of oxygen-containing and nitrogen-containing groups. The adsorption behaviors of NMC materials for anionic dye methyl orange (MO) were investigated, which are fit excellent for the Langmuir isothermal adsorption equation. All the materials exhibited high adsorption capacity for MO at room temperature. Their adsorption capacity can be adjusted by changing the nitrogen contents in NMC materials. Moreover, treating the NMC material at higher temperature can significantly improve the adsorption capacity for MO. According to the results of characterization, the main features of NMC materials, like large pore size and abundant basic nitrogen-containing groups on the surface, should be related to the excellent adsorption property for MO. PMID:26748066

  6. Effective removal of hexavalent chromium from aqueous solutions by adsorption on mesoporous carbon microspheres.

    PubMed

    Zhou, Jianguo; Wang, Yuefeng; Wang, Jitong; Qiao, Wenming; Long, Donghui; Ling, Licheng

    2016-01-15

    High-surface-area mesoporous carbon microspheres were successfully synthesized by a spraying method with the purpose of removing Cr(VI) from waste water. Various factors influencing the adsorption of Cr(VI), including pH, adsorption temperature, and contact time were studied. As the adsorption process was pH dependent, it showed maximum removal efficiency of Cr(VI) at pH 3.0. Pseudo-second-order model was found to best represent the kinetics of Cr(VI) adsorption. The adsorption parameters were determined using both Langmuir and Freundlich isotherm models, and Qm value was as high as 165.3mg/g. The thermodynamic parameters including standard Gibb's free energy (ΔG(0)), standard enthalpy (ΔH(0)) and standard entropy (ΔS(0)) were investigated for predicting the nature of adsorption, which suggested the adsorption was an endothermic and a spontaneous thermodynamically process. Furthermore, Fe3O4-loaded MCMs were prepared to rapidly separate the adsorbent from the solution by a simple magnetic process. Fe3O4-loaded MCMs had a high adsorption capacity of 156.3mg/g, and a good regeneration ability with a capacity of 123.9mg/g for the fifth adsorption-desorption cycle. PMID:26454379

  7. Hydrophilic mesoporous carbon nanospheres with high drug-loading efficiency for doxorubicin delivery and cancer therapy

    PubMed Central

    Wang, Huan; Li, Xiangui; Ma, Zhiqiang; Wang, Dan; Wang, Linzhao; Zhan, Jieqiong; She, Lan; Yang, Feng

    2016-01-01

    In this study, a highly effective transmembrane delivery vehicle based on PEGylated oxidized mesoporous carbon nanosphere (oMCN@PEG) was successfully fabricated in a facile strategy. oMCN@PEG exhibited a narrow size distribution of 90 nm, excellent hydrophilicity, good biocompatibility, and a very high loading efficiency for doxorubicin (DOX). The drug system (oMCN@DOX@PEG) exhibited excellent stability under neutral pH conditions, but with dramatic releases of DOX at reduced pH conditions. Pharmacokinetics study revealed that oMCN@DOX@PEG could prolong the circulation of DOX in the blood stream. The endocytosis, cytotoxicity, and anticancer effect in vitro and in vivo of the drug-loaded nanoparticles were also evaluated. Our results showed that the nanoparticles efficiently penetrated the membrane of tumor cells, subsequently released drugs, and efficiently inhibited the growth of cancer cells both in vitro and in vivo. Especially, oMCN@DOX@PEG also exhibited significant antimetastasis effect in advanced stage of malignant cancer, improving the survival time of tumor-bearing mice. The results suggested that oMCN@PEG might be a promising anticancer drug delivery vehicle for cancer therapy. PMID:27175077

  8. Amorphous Red Phosphorus Embedded in Highly Ordered Mesoporous Carbon with Superior Lithium and Sodium Storage Capacity.

    PubMed

    Li, Weihan; Yang, Zhenzhong; Li, Minsi; Jiang, Yu; Wei, Xiang; Zhong, Xiongwu; Gu, Lin; Yu, Yan

    2016-03-01

    Red phosphorus (P) have been considered as one of the most promising anode material for both lithium-ion batteries (LIBs) and (NIBs), because of its high theoretical capacity. However, natural insulating property and the large volume expansion of red P during cycling lead to poor cyclability and low rate performance, which prevents its practical application. Here, we significantly improves both lithium storage and sodium storage performance of red P by confining nanosized amorphous red P into the mesoporous carbon matrix (P@CMK-3) using a vaporization-condensation-conversion process. The P@CMK-3 shows a high reversible specific capacity of ∼2250 mA h g(-1) based on the mass of red P at 0.25 C (∼971 mA h g(-1) based on the composite), excellent rate performance of 1598 and 624 mA h g(-1) based on the mass of red P at 6.1 and 12 C, respectively (562 and 228 mA h g(-1) based on the mass of the composite at 6.1 and 12 C, respectively) and significantly enhanced cycle life of 1150 mA h g(-1) based on the mass of red P at 5 C (500 mA h g(-1) based on the mass of the composite) after 1000 cycles for LIBs. For Na ions, it also displays a reversible capacity of 1020 mA h g(-1) based on the mass of red P (370 mA h g(-1) based on the mass of the composite) after 210 cycles at 5C. The significantly improved electrochemical performance could be attributed to the unique structure that combines a variety of advantages: easy access of electrolyte to the open channel structure, short transport path of ions through carbon toward the red P, and high ionic and electronic conductivity. PMID:26866666

  9. Thin-Layer Polymer Wrapped Enzymes Encapsulated in Hierarchically Mesoporous Silica with High Activity and Enhanced Stability

    NASA Astrophysics Data System (ADS)

    Zhang, Fang; Wang, Meitao; Liang, Chao; Jiang, Huangyong; Shen, Jian; Li, Hexing

    2014-03-01

    A novel soft-hard cooperative approach was developed to synthesize bioactive mesoporous composite by pre-wrapping Penicillin G amidase with poly(acrylaimde) nanogel skin and subsequently incorporating such Penicillin G amidase nanocapsules into hierarchically mesoporous silica. The as-received bioactive mesoporous composite exhibited comparable activity and extraordinarily high stability in comparison with native Penicillin G amidase and could be used repetitively in the water-medium hydrolysis of penicillin G potassium salt. Furthermore, this strategy could be extended to the synthesis of multifunctional bioactive mesoporous composite by simultaneously introducing glucose oxidase nanocapsules and horseradish peroxidase nanocapsules into hierarchically mesoporous silica, which demonstrated a synergic effect in one-pot tandem oxidation reaction. Improvements in the catalytic performances were attributed to the combinational unique structure from soft polymer skin and hard inorganic mesoporous silica shell, which cooperatively helped enzyme molecules to retain their appropriate geometry and simultaneously decreased the enzyme-support negative interaction and mass transfer limitation under heterogeneous conditions.

  10. Thin-Layer Polymer Wrapped Enzymes Encapsulated in Hierarchically Mesoporous Silica with High Activity and Enhanced Stability

    PubMed Central

    Zhang, Fang; Wang, Meitao; Liang, Chao; Jiang, Huangyong; Shen, Jian; Li, Hexing

    2014-01-01

    A novel soft-hard cooperative approach was developed to synthesize bioactive mesoporous composite by pre-wrapping Penicillin G amidase with poly(acrylaimde) nanogel skin and subsequently incorporating such Penicillin G amidase nanocapsules into hierarchically mesoporous silica. The as-received bioactive mesoporous composite exhibited comparable activity and extraordinarily high stability in comparison with native Penicillin G amidase and could be used repetitively in the water-medium hydrolysis of penicillin G potassium salt. Furthermore, this strategy could be extended to the synthesis of multifunctional bioactive mesoporous composite by simultaneously introducing glucose oxidase nanocapsules and horseradish peroxidase nanocapsules into hierarchically mesoporous silica, which demonstrated a synergic effect in one-pot tandem oxidation reaction. Improvements in the catalytic performances were attributed to the combinational unique structure from soft polymer skin and hard inorganic mesoporous silica shell, which cooperatively helped enzyme molecules to retain their appropriate geometry and simultaneously decreased the enzyme-support negative interaction and mass transfer limitation under heterogeneous conditions. PMID:24651701

  11. Challenges in Fabrication of Mesoporous Carbon Films with Ordered Cylindrical Pores via Phenolic Oligomer Self-Assembly with Triblock Copolymers

    SciTech Connect

    Song, Lingyan; Feng, Dan; Fredin, Nathaniel J.; Yager, Kevin G.; Jones, Ronald L.; Wu, Quanyan; Zhao, Dongyuan; Vogt, Bryan D.

    2010-06-22

    Mesoporous phenol formaldehyde (PF) polymer resin and carbon films are prepared by a solution self-assembly of PF oligomers with amphiphilic triblock copolymers. After thermopolymerization of the PF to cross-link the network, the films show an ordered morphology as determined by X-ray diffraction and grazing incidence small-angle X-ray scattering (GISAXS). Our results show that the amphiphilic triblock copolymer template greatly influences the stability of the final porous mesostructures. The pyrolysis of the two-dimensional (2-D) hexagonal films with p6mm symmetry templated by Pluronic F127 yields a disordered porous structure following the template removal. Conversely, films templated by Pluronic P123 can exhibit well-ordered cylindrical pores after the template removal, but the solution composition range to yield ordered cylindrical mesopores is significantly reduced (nearly 70%) for thin films in comparison to bulk powders. We propose two dominant difficulties in fabricating well-ordered cylindrical mesopores in films: first, the stress from contraction during the pyrolysis can lead to a collapse of the mesostructure if the wall thickness is insufficient, and second, the surface wetting behavior in thin films leads to a small compositional range.

  12. The Effect of Synthesis Conditions on Mesoporous Structure and the Photocatalytic Activity of TiO2 Nanoparticles.

    PubMed

    Myilsamy, M; Murugesan, V; Mahalakshmi, M

    2015-06-01

    Mesoporous TiO2 nanoparticles have been synthesized by sol-gel method in different preparation conditions to investigate the effect of triblock copolymer, acetic acid and water on mesoporous structure and the photocatalytic activity. The synthesized photocatalysts were characterized by means of X-ray powder diffraction, Nitrogen adsorption/desorption studies, High resolution transmission electron microscopy, Scanning electron microscopy, Diffuse reflectance UV-Vis spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis. Among the various synthesized materials, mesoporous TiO2 synthesized using triblock copolymer as a structure directing template in acetic acid medium with high water ratio calcined at 400 degrees C was found to have the highest photocatalytic activity due to the enhanced band gap energy, high specific surface area and high average pore size. The large mesopores provide more pathways for the reactants to enter and products to escape and enhances the adsorption of methylene blue. The photocatalytic activity decreases with increase of solution pH. The rate of *OH formation is high at lower pH, which enhances the photocatalytic activity was revealed by photoluminescence technique. In addition, the adsorbed hydroxyl groups on the surface of mesoporous TiO2 particles can interact with photogenerated holes to produce more *OH radicals, which enhances charge transfer efficiency and enhances the rate of *OH formation. PMID:26369095

  13. Sulfur-doped ordered mesoporous carbons: A stability-improving sulfur host for lithium-sulfur battery cathodes

    NASA Astrophysics Data System (ADS)

    Nitze, Florian; Fossum, Kjell; Xiong, Shizhao; Matic, Aleksandar; Palmqvist, Anders E. C.

    2016-06-01

    We report on sulfur-functionalized ordered mesoporous carbons aimed for lithium-sulfur battery electrode applications with improved charge capacity retention. The carbons were obtained by a hard-template strategy using a mixture of furfuryl alcohol and furfuryl mercaptan. For the application as electrode material in lithium-sulfur batteries, the carbons were additionally loaded with sulfur following a traditional melt-diffusion approach. It was found that the sulfur interacts stronger with the sulfur-functionalized carbon matrix than with the non-functionalized material. Electrodes showed very high capacity in the second discharge-charge cycle amounting to approximately 1500, 1200 and 1400 mAh/g (sulfur) for carbon materials with no, medium and high degrees of sulfur functionalization, respectively. More importantly, the sulfur-functionalization of the carbon was found to increase the capacity retention after 50 discharge-charge cycles by 8 and 5% for the carbons with medium and high degrees of sulfur-functionalization, respectively, compared to carbon with no sulfur-functionalization. We attribute this significant improvement to the presence of covalently bound sulfur groups at the internal surface of the functionalized carbon providing efficient anchoring sites for catenation to the sulfur loaded into the pores of the carbons and provide experimental support for this in the form of results from cyclic voltammetry and X-ray photoelectron spectroscopy.

  14. Bioresponsive carbon nano-gated multifunctional mesoporous silica for cancer theranostics

    NASA Astrophysics Data System (ADS)

    Prasad, Rajendra; Aiyer, Sandhya; Chauhan, Deepak S.; Srivastava, Rohit; Selvaraj, Kaliaperumal

    2016-02-01

    Designing bioresponsive nanocarriers for controlled and efficient intracellular drug release for cancer therapy is a major thrust area in nanomedicine. With recent recognition by the US FDA as a safe material for human trials, mesoporous silica nanoparticles (MSNPs) are being extensively explored as promising theranostic agents. Green fluorescent carbon quantum dots (CQDs), though known as possible alternatives for their more toxic and relatively less efficient predecessors, are less known as gate keepers for drug release control. We report for the first time an efficient bioresponse of CQDs when judiciously designed using glutathione cleavable (redox responsive) disulphide bonds. When the anticancer drug doxorubicin loaded MSNPs are capped with these CQDs, they display promising drug release control on exposure to a mimicked intracellular cancer environment. Their dual functionality is well established with good control on preventing the premature release and exceptional bio-imaging of HeLa cancer cells. Fluorescence images prove selective targeting of HeLa cells by overexpression of folate receptors from the surface functionalised folic acid ligand. Extensive characterisation using XRD, TEM, BET analysis, drug loading tests, drug release kinetics, MTT assay and fluoroscence cell imaging helps in understanding the multifunctionalities of the successful design, extending its scope with exciting prospects towards non-invasive targeted drug delivery and bio-imaging for effective cancer diagnosis and treatment.Designing bioresponsive nanocarriers for controlled and efficient intracellular drug release for cancer therapy is a major thrust area in nanomedicine. With recent recognition by the US FDA as a safe material for human trials, mesoporous silica nanoparticles (MSNPs) are being extensively explored as promising theranostic agents. Green fluorescent carbon quantum dots (CQDs), though known as possible alternatives for their more toxic and relatively less efficient predecessors, are less known as gate keepers for drug release control. We report for the first time an efficient bioresponse of CQDs when judiciously designed using glutathione cleavable (redox responsive) disulphide bonds. When the anticancer drug doxorubicin loaded MSNPs are capped with these CQDs, they display promising drug release control on exposure to a mimicked intracellular cancer environment. Their dual functionality is well established with good control on preventing the premature release and exceptional bio-imaging of HeLa cancer cells. Fluorescence images prove selective targeting of HeLa cells by overexpression of folate receptors from the surface functionalised folic acid ligand. Extensive characterisation using XRD, TEM, BET analysis, drug loading tests, drug release kinetics, MTT assay and fluoroscence cell imaging helps in understanding the multifunctionalities of the successful design, extending its scope with exciting prospects towards non-invasive targeted drug delivery and bio-imaging for effective cancer diagnosis and treatment. Electronic supplementary information (ESI) available: Size distribution histograms, PL spectra of CQDs at different pH values and at different excitation wavelengths, TEM images and the FTIR spectrum. See DOI: 10.1039/c5nr06756a

  15. Supercritical-assistant liquid crystal template approach to synthesize mesoporous titania/multiwalled carbon nanotube composites with high visible-light driven photocatalytic performance

    SciTech Connect

    Liu, Chen; Li, Youji Xu, Peng; Li, Ming; Huo, Pingxiang

    2014-12-15

    Graphical abstract: We investigate the influence of mesoporous titania content upon the visible-light driven photocatalytic performance of MPT/MWCNTs in phenol degradation. - Highlights: • MPT/MWCNTs were fabricated by liquid-crystal template in supercritical CO{sub 2}. • MPT/MWCNTs show high visible-light driven photoactivity for phenol degradation. • MPT/MWCNTs also show high reusable photoactivity under visible irradiation. • MPT content can control visible-light driven photoactivity of MPT/MWCNTs. • MPT is not easily broken away from from MPT/MWCNT composites. - Abstract: Mesoporous titania (MPT) was deposited onto multiwalled carbon nanotubes (MWCNTs) by deposition of titanium sol containing liquid-crystal template with assistant of supercritical CO{sub 2}. The products were characterized with various analytical techniques to determine their structural, morphological, optical absorption and photocatalytic properties. The results indicate that in photocatalytic degradation of phenol under visible light, the mixtures or composites of MPT and MWCNT show the high efficiency because of synergies between absorbing visible light, releasing electrons and facilitating transfer of charge carriers of MWCNTs and providing activated centers of MPT. Because of the mutual constraint between MPT and MWCNTs on the photocatalytic efficiency, the optimal loading of MPT in MPT/MWCNT-3 for phenol degradation is 48%. Because the intimate contact between MWCNTs and MPT is more beneficial to electron transformation, photoactivity of mixture is lower than that of composites with high reusable performance. The optimum conditions of phenol degradation were obtained.

  16. Preparation of activated carbons from walnut wood: a study of microporosity and fractal dimension

    NASA Astrophysics Data System (ADS)

    Gómez-Serrano, Vicente; Cuerda-Correa, Eduardo M.; Fernández-González, M. Carmen; Alexandre-Franco, María F.; Macías-García, Antonio

    2005-04-01

    Agricultural and forest residues constitute an extraordinarily important source of precursors for the manufacture of activated carbons. Activated carbons are well known as porous solids with a highly developed apparent surface area. In the present work, activated carbon has been prepared from forest residues of walnut tree wood (a raw material not studied until now) by physical activation. Raw material has been carbonized between 573 and 1073 K and afterwards activated in air at temperatures between 623 and 823 K. The apparent surface area, micropore volume, mesopore volume and fractal dimension of the samples prepared have been calculated.

  17. Polymer-templated mesoporous carbons synthesized in the presence of nickel nanoparticles, nickel oxide nanoparticles, and nickel nitrate

    NASA Astrophysics Data System (ADS)

    Choma, Jerzy; Jedynak, Katarzyna; Marszewski, Michal; Jaroniec, Mietek

    2012-02-01

    Mesoporous carbon composites, containing nickel and nickel oxide nanoparticles, were obtained by soft-templating method. Samples were synthesized under acidic conditions using resorcinol and formaldehyde as carbon precursors, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock co-polymer Lutrol F127 as a soft template and nickel and nickel oxide nanoparticles, and nickel nitrate as metal precursors. In addition, a one set of samples was obtained by impregnation of mesoporous carbons with a nickel nitrate solution followed by further annealing at 400 °C. Wide angle X-ray powder diffraction along with thermogravimetric analysis proved the presence of nickel nanoparticles in the final composites obtained using nickel and nickel oxide nanoparticles, and Ni(NO3)2 solution. Whereas, the impregnation of carbons with a nickel nitrate solution followed by annealing at 400 °C resulted in needle-like nickel oxide nanoparticles present inside the composites’ pores. Low-temperature (-196 °C) nitrogen physisorption, X-ray powder diffraction, and thermogravimetric analysis confirmed good adsorption and structural properties of the synthesized nickel-carbon composites, in particular, the samples possessed high surface areas (>600 m2/g), large total pore volumes (>0.50 cm3/g), and maxima of pore size distribution functions at circa 7 nm. It was found that the composites were partially graphitized during carbonization process at 850 °C. The samples are stable in an air environment below temperature of 500 °C. All these features make the synthesized nickel-carbon composites attractive materials for adsorption, catalysis, energy storage, and environmental applications.

  18. 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 (? > 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. PMID:25019939

  19. Immobilization of Zidovudine Derivatives on the SBA-15 Mesoporous Silica and Evaluation of Their Cytotoxic Activity

    PubMed Central

    Lewandowski, Dawid

    2015-01-01

    Novel zidovudine derivatives, able to be covalently conjugated to silica surface, have been obtained and grafted to SBA-15 mesoporous silica. Cytotoxic activity of the hybrid organic-inorganic (zidovudine derivatives-silica) systems against HeLa and KB cell lines has been analyzed. Addition of folic acid had a positive influence on the cytotoxicity. Up to 69% of HeLa and 65% of KB tumor cells growth inhibition has been achieved at low silica concentration used (10 μg/mL). PMID:25942021

  20. Smaller Pt particles supported on mesoporous bowl-like carbon for highly efficient and stable methanol oxidation and oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Yan, Zaoxue; Zhang, Mingmei; Xie, Jimin; Wang, Hongen; Wei, Wei

    2013-12-01

    Bowl-like carbons (BLCs) with mesoporous structure are prepared using glucose as carbon source and solid core mesoporous shell silica spheres (SCMSSs) as templates. Pt particles are then loaded on the BLCs as electrocatalyst and used for both methanol oxidation and oxygen reduction reaction (ORR) in acidic media. Physical measurements display that the BLCs are formed due to flowing of melted glucose along the mesoporous shell of the SCMSSs. Moreover, the BLCs with high surface area (1108.3 m2 g-1), large pore volume (2.7 cm3 g-1) and mesoporous structure (9.4 nm in diameter) are beneficial for uniform dispersion and stable loading of smaller noble metal particles, and efficiently improve the mass transfer in catalytic reactions, compared to carbon powders. Cyclic voltammogram measurements show that the mass current densities on Pt/BLC electrocatalyst are 2.6 times (1846 mA mgPt-1) for methanol oxidation and 1.6 times (180.6 mA mgPt-1) for ORR as high as that of commercial Pt/C (TKK). Furthermore, the mesopores give Pt/BLC more electrocatalytic stability due to stronger physical interaction force.

  1. Iron oxide nanoparticles embedded in activated carbons prepared from hydrothermally treated waste biomass.

    PubMed

    Hao, Wenming; Björkman, Eva; Yun, Yifeng; Lilliestråle, Malte; Hedin, Niklas

    2014-03-01

    Particles of iron oxide (Fe3O4 ; 20–40 nm) were embedded within activated carbons during the activation of hydrothermally carbonized (HTC) biomasses in a flow of CO2. Four different HTC biomass samples (horse manure, grass cuttings, beer production waste, and biosludge) were used as precursors for the activated carbons. Nanoparticles of iron oxide formed from iron catalyst included in the HTC biomasses. After systematic optimization, the activated carbons had specific surface areas of about 800 m2g1. The pore size distributions of the activated carbons depended strongly on the degree of carbonization of the precursors. Activated carbons prepared from highly carbonized precursors had mainly micropores, whereas those prepared from less carbonized precursors contained mainly mesopores. Given the strong magnetism of the activated carbon–nano-Fe3O4 composites, they could be particularly useful for water purification. PMID:24678001

  2. Mesoporous carbon originated from non-permanent porous MOFs for gas storage and CO2/CH4 separation

    PubMed Central

    Wang, Wenjing; Yuan, Daqiang

    2014-01-01

    Four nanoporous carbons prepared by direct carbonization of non-permanent highly porous MOF [Zn3(BTC)2·(H2O)3]n without any additional carbon precursors. The carbonization temperature plays an important role in the pore structures of the resultant carbons. The Brunauer-Emmett-Teller (BET) surface areas of four carbon materials vary from 464 to 1671 m2 g−1 for different carbonization temperature. All the four carbon materials showed a mesoporous structure centered at ca. 3 nm, high surface area and good physicochemical stability. Hydrogen, methane and carbon dioxide sorption measurements indicated that the C1000 has good gas uptake capabilities. The excess H2 uptake at 77 K and 17.9 bar can reach 32.9 mg g−1 and the total uptake is high to 45 mg g−1. Meanwhile, at 95 bar, the total CH4 uptake can reach as high as 208 mg g−1. Moreover the ideal adsorbed solution theory (IAST) prediction exhibited exceptionally high adsorption selectivity for CO2/CH4 in an equimolar mixture at 298 K and 1 bar (Sads = 27) which is significantly higher than that of some porous materials in the similar condition. PMID:25026895

  3. The mechanism for increasing the oral bioavailability of poorly water-soluble drugs using uniform mesoporous carbon spheres as a carrier.

    PubMed

    Wang, Tianyi; Zhao, Peng; Zhao, Qinfu; Wang, Bing; Wang, Siling

    2016-02-01

    Uniform mesoporous carbon spheres (UMCS) were used as a carrier to improve the bioavailability of the model drug, celecoxib (CEL). Furthermore, we investigated the mechanism responsible for the improved bioavailability of CEL. The association, adhesion and uptake of UMCS by intestinal epithelial cells were studied by transmission electron microscopy (TEM), fluorescence-activated cell sorting (FACS) and laser confocal scanning microscopy (LCSM). UMCS was found to promote cellular uptake of CEL. Drug transport in Caco-2 cell monolayers proved that UMCS can significantly reduce the rate of drug efflux and improve CEL permeability. The dissolution rate of CEL from drug-loaded samples was markedly improved compared with pure crystalline CEL; moreover, oral bioavailability of CEL loaded into UMCS was also markedly improved compared with that of commercially available capsules. UMCS indicates the advantages and potential of this method to achieve improved oral absorption by increasing the dissolution rate, cellular uptake and permeability of the drug. PMID:24870199

  4. Robust conductive mesoporous carbon-silica composite films with highly ordered and oriented orthorhombic structures from triblock-copolymer template co-assembly

    SciTech Connect

    Song, Lingyan; Feng, Dan; Campbell, Casey G; Gu, Dong; Forster, Aaron M; Yager, Kevin G; Fredin, Nathaniel; Lee, Hae-Jeong; Jones, Ronald L; Zhao, Dongyuan; Vogt, Bryan D

    2012-07-11

    In this work, we describe a facile approach to improve the robustness of conductive mesoporous carbon-based thin films by the addition of silica to the matrix through the triconstituent organic-inorganic-organic co-assembly of resol (carbon precursor) and tetraethylorthosilicate (silica precursor) with triblock-copolymer Pluronic F127. The pyrolysis of the resol-silica-pluronic F127 film yields a porous composite thin film with well-defined mesostructure. X-Ray diffraction (XRD), grazing incidence small angle X-ray scattering (GISAXS), and electron microscopy measurements indicate that the obtained carbon-based thin films have a highly ordered orthorhombic mesostructure (Fmmm) with uniform large pore size (~3 nm). The orthorhombic mesostructure is oriented and the (010) plane is parallel to the silicon wafer substrate. The addition of silica to the matrix impacts the pore size, surface area, porosity, modulus and conductivity. For composite films with approximately 40 wt% silica, the conductivity is decreased by approximately an order of magnitude in comparison to a pure carbon mesoporous film, but the conductivity is comparable to typical printed carbon inks used in electrochemical sensing, {approx}10 S cm-1. The mechanical properties of these mesoporous silica-carbon hybrid films are similar to the pure carbon analogs with a Young's modulus between 10 GPa and 15 GPa, but the material is significantly more porous. Moreover, the addition of silica to the matrix appears to improve the adhesion of the mesoporous film to a silicon wafer. These mesoporous silica-carbon composite films have appropriate characteristics for use in sensing applications.

  5. Synthesis of three-dimensionally ordered macro-/mesoporous Pt with high electrocatalytic activity by a dual-templating approach

    NASA Astrophysics Data System (ADS)

    Zhang, Chengwei; Yang, Hui; Sun, Tingting; Shan, Nannan; Chen, Jianfeng; Xu, Lianbin; Yan, Yushan

    2014-01-01

    Three dimensionally ordered macro-/mesoporous (3DOM/m) Pt catalysts are fabricated by chemical reduction employing a dual-templating synthesis approach combining both colloidal crystal (opal) templating (hard-templating) and lyotropic liquid crystal templating (soft-templating) techniques. The macropore walls of the prepared 3DOM/m Pt exhibit a uniform mesoporous structure composed of polycrystalline Pt nanoparticles. Both the size of the mesopores and Pt nanocrystallites are in the range of 3-5 nm. The 3DOM/m Pt catalyst shows a larger electrochemically active surface area (ECSA), and higher catalytic activity as well as better poisoning tolerance for methanol oxidation reaction (MOR) than the commercial Pt black catalyst.

  6. Real Understanding of the Nitrogen-Doping Effect on the Electrochemical Performance of Carbon Materials by Using Carbon-Coated Mesoporous Silica as a Model Material.

    PubMed

    Castro-Muñiz, Alberto; Hoshikawa, Yasuto; Kasukabe, Takatoshi; Komiyama, Hiroshi; Kyotani, Takashi

    2016-03-01

    The main aim of the present work is to precisely understand the sole effect of nitrogen doping on the electrochemical performance of porous carbon materials. To achieve this objective, the whole surface of mesoporous silica (SBA-15) was coated with a thin layer of carbon (about 0.4 nm) with and without N-doping by using acetonitrile and acetylene chemical vapor deposition, respectively. The resulting N-doped and nondoped carbon-coated silica samples have mesopore structures identical to those in the original SBA-15, and they are practically the same in terms of not only the pore size and pore structure but also the particle size distribution and particle morphology, with the exception of N-doping, which makes them unique model materials to extract the sole effect of nitrogen on the performances of electrochemical capacitors and electrocatalytic oxygen reduction. Moreover, the outstanding features of the carbon-coated silica samples allow even a quantitative understanding of the pseudocapacitance induced by nitrogen functionalities on the carbon surface in an acidic aqueous electrolyte. PMID:26859703

  7. Synthesis of mesoporous sulfur-doped Ta2O5 nanocomposites and their photocatalytic activities.

    PubMed

    Ismail, Adel A; Faisal, M; Harraz, Farid A; Al-Hajry, A; Al-Sehemi, A G

    2016-06-01

    Mesoporous sulfur (S)-doped Ta2O5 nanocomposites have been synthesized for the first time through the sol-gel reaction of tantalum chloride and thiourea in the presence of a F127 triblock copolymer as structure directing agent. The as-formed mesophase S-doped Ta2O5 hybrid gels were calcined at 700°C for 4h to obtain mesoporous S-Ta2O5 nanocomposites. The experimental results indicated that the surface area of the S-doped Ta2O5 was up to 50m(2)g(-1) and the pore diameter was controllable in the range of 3-7.7nm. The S-doped Ta2O5 nanocomposites behave as superior visible light-sensitive photocatalysts and the 1.5at.% S-doped Ta2O5 (S1.5) photocatalyst exhibited excellent photocatalytic activity of ∼92% for the photodegradation of methylene blue, identical to 80% TOC removal after three hours illumination under visible light. The photodegradation rate of S1.5 photocatalyst showed 3.4 times higher than the undoped Ta2O5 due to their narrow bandgap, large surface area, mesostructure and well crystalline state. The S1.5 photocatalyst could be recycled at least five times without an apparent decrease in its photocatalytic efficiency, indicating its high stability for practical applications. To the best of our knowledge, this is the first report that demonstrates one-step synthesis of mesoporous S-doped Ta2O5 nanocomposites as an efficient photocatalysts under visible light illumination. PMID:27017474

  8. Hierarchically structured activated carbon for ultracapacitors

    PubMed Central

    Kim, Mok-Hwa; Kim, Kwang-Bum; Park, Sun-Min; Roh, Kwang Chul

    2016-01-01

    To resolve the pore-associated bottleneck problem observed in the electrode materials used for ultracapacitors, which inhibits the transport of the electrolyte ions, we designed hierarchically structured activated carbon (HAC) by synthesizing a mesoporous silica template/carbon composite and chemically activating it to simultaneously remove the silica template and increase the pore volume. The resulting HAC had a well-designed, unique porous structure, which allowed for large interfaces for efficient electric double-layer formation. Given the unique characteristics of the HAC, we believe that the developed synthesis strategy provides important insights into the design and fabrication of hierarchical carbon nanostructures. The HAC, which had a specific surface area of 1,957 m2 g−1, exhibited an extremely high specific capacitance of 157 F g−1 (95 F cc−1), as well as a high rate capability. This indicated that it had superior energy storage capability and was thus suitable for use in advanced ultracapacitors. PMID:26878820

  9. Hierarchically structured activated carbon for ultracapacitors.

    PubMed

    Kim, Mok-Hwa; Kim, Kwang-Bum; Park, Sun-Min; Roh, Kwang Chul

    2016-01-01

    To resolve the pore-associated bottleneck problem observed in the electrode materials used for ultracapacitors, which inhibits the transport of the electrolyte ions, we designed hierarchically structured activated carbon (HAC) by synthesizing a mesoporous silica template/carbon composite and chemically activating it to simultaneously remove the silica template and increase the pore volume. The resulting HAC had a well-designed, unique porous structure, which allowed for large interfaces for efficient electric double-layer formation. Given the unique characteristics of the HAC, we believe that the developed synthesis strategy provides important insights into the design and fabrication of hierarchical carbon nanostructures. The HAC, which had a specific surface area of 1,957 m(2) g(-1), exhibited an extremely high specific capacitance of 157 F g(-1) (95 F cc(-1)), as well as a high rate capability. This indicated that it had superior energy storage capability and was thus suitable for use in advanced ultracapacitors. PMID:26878820

  10. Hierarchically structured activated carbon for ultracapacitors

    NASA Astrophysics Data System (ADS)

    Kim, Mok-Hwa; Kim, Kwang-Bum; Park, Sun-Min; Roh, Kwang Chul

    2016-02-01

    To resolve the pore-associated bottleneck problem observed in the electrode materials used for ultracapacitors, which inhibits the transport of the electrolyte ions, we designed hierarchically structured activated carbon (HAC) by synthesizing a mesoporous silica template/carbon composite and chemically activating it to simultaneously remove the silica template and increase the pore volume. The resulting HAC had a well-designed, unique porous structure, which allowed for large interfaces for efficient electric double-layer formation. Given the unique characteristics of the HAC, we believe that the developed synthesis strategy provides important insights into the design and fabrication of hierarchical carbon nanostructures. The HAC, which had a specific surface area of 1,957 m2 g-1, exhibited an extremely high specific capacitance of 157 F g-1 (95 F cc-1), as well as a high rate capability. This indicated that it had superior energy storage capability and was thus suitable for use in advanced ultracapacitors.

  11. Amperometric catechol biosensor based on laccase immobilized on nitrogen-doped ordered mesoporous carbon (N-OMC)/PVA matrix

    NASA Astrophysics Data System (ADS)

    Guo, Meiqing; Wang, Hefeng; Huang, Di; Han, Zhijun; Li, Qiang; Wang, Xiaojun; Chen, Jing

    2014-06-01

    A functionalized nitrogen-containing ordered mesoporous carbon (N-OMC), which shows good electrical properties, was synthesized by the carbonization of polyaniline inside a SBA-15 mesoporous silica template. Based on this, through entrapping laccase onto the N-OMC/polyvinyl alcohol (PVA) film a facilely fabricated amperometric biosensor was developed. Laccase from Trametes versicolor was assembled on a composite film of a N-OMC/PVA modified Au electrode and the electrochemical behavior was investigated. The results indicated that the N-OMC modified electrode exhibits electrical properties towards catechol. The optimum experimental conditions of a biosensor for the detection of catechol were studied in detail. Under the optimal conditions, the sensitivity of the biosensor was 0.29 A*M-1 with a detection limit of 0.31 μM and a linear detection range from 0.39 μM to 8.98 μM for catechol. The calibration curve followed the Michaelis-Menten kinetics and the apparent Michaelis-Menten \\left( K_{M}^{app} \\right) was 6.28 μM. This work demonstrated that the N-OMC/PVA composite provides a suitable support for laccase immobilization and the construction of a biosensor.

  12. Enzyme-capped relay-functionalized mesoporous carbon nanoparticles: effective bioelectrocatalytic matrices for sensing and biofuel cell applications.

    PubMed

    Trifonov, Alexander; Herkendell, Katharina; Tel-Vered, Ran; Yehezkeli, Omer; Woerner, Michael; Willner, Itamar

    2013-12-23

    The porous high surface area and conducting properties of mesoporous carbon nanoparticles, CNPs (<500 nm diameter of NPs, pore dimensions ∼6.3 nm), are implemented to design electrically contacted enzyme electrodes for biosensing and biofuel cell applications. The relay units ferrocene methanol, Fc-MeOH, methylene blue, MB(+), and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid), ABTS(2-), are loaded in the pores of the mesoporous CNPs, and the pores are capped with glucose oxidase, GOx, horseradish peroxidase, HRP, or bilirubin oxidase, BOD, respectively. The resulting relay/enzyme-functionalized CNPs are immobilized on glassy carbon electrodes, and the relays encapsulated in the pores are sufficiently free to electrically contact the different enzymes with the bulk electrode supports. The Fc-MeOH/GOx CNP-functionalized electrode is implemented for the bioelectrocatalyzed sensing of glucose, and the MB(+)/HRP-modified CNPs are applied for the electrochemical sensing of H2O2. The ABTS(2-)/BOD-modified CNPs provide an effective electrically contacted material for the bioelectrocatalyzed reduction of O2 (kcat = 94 electrons·s(-1)). Integration of the Fc-MeOH/GOx CNP electrode and of the electrically wired ABTS(2-)/BOD CNP electrode as anode and cathode, respectively, yields a biofuel cell revealing a power output of ∼95 μW·cm(-2). PMID:24266869

  13. Multiple constituents co-assembly of ordered mesoporous Al2O3-SiO2-carbon nanocomposites.

    PubMed

    Wang, Wei; Xue, Huanhuan; Feng, Cuimiao; Kong, Lina; Zhao, Qingfei; Wan, Ying

    2013-02-01

    Ordered mesoporous Al2O3-SiO2-carbon nanocomposites have been synthesized via the direct triblock-copolymer self-assembly route using soluble phenolic resols as polymer precursors, aluminium chloride hexahydrate as an aluminum precursor, tetraethoxysilane as a silica precursor, and Pluronic F127 as a template. Characterization of XRD, N2 sorption isotherms, TEM, solid-state NMR, TG, and NH3-TPD techniques is used to investigate the mesostructure, pore properties, phase composition, metal incorporation state, and acidic properties. Ordered mesoporous nanocomposites have "reinforced concrete"-structured frameworks, in which the oxide and carbon components are microphase separated and homogenously dispersed inside pore walls. Al species are tetrahedrally incorporated into silica frameworks to compose the inorganic oxide compounds which provides acidic center. The nanocomposites have the ordered 2-D hexagonal mesostructure, high surface areas (291-360 m2/g), large pore volumes (0.25-0.42 cm3/g), large pore diameters (- 5 nm) and accessible acidic sites. PMID:23646686

  14. Hollow mesoporous titania microspheres: New technology and enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Feng, Zhenliang; Wei, Wenrui; Wang, Litong; Hong, Ruoyu

    2015-12-01

    Hollow titania microspheres (HTS) were fabricated via a sol-gel process by coating the hydrolysis product of titanium tetrabutoxide (TBOT) onto the amino (-NH2) modified porous polystyrene cross-linked divinyl benzene (PS-DVB) microspheres under changing atmospheric pressure, followed by calcination in nitrogen and air atmosphere. Particularly, the atmospheric pressure was continuously and regularly changed during the formation process of PS-DVB@TiO2 microspheres. Then the TiO2 particles were absorbed into the pores and onto the surface of PS-DVB as well. The resultant HTS (around 2 μm in diameter) featured a high specific surface area (84.37 m2/g), anatase crystal and stable hollow microsphere structure, which led to high photocatalysis activity. The photocatalytic degradation of malachite green (MG) organic dye solution was conducted under ultraviolet (UV) light irradiation, which showed a high photocatalytic ability (81% of MG was degraded after UV irradiation for 88 min). Therefore, it could be potentially applied for the treatment of wastewater contaminated by organic pollutants.

  15. Uniform dispersion of 1 : 1 PtRu nanoparticles in ordered mesoporous carbon for improved methanol oxidation.

    PubMed

    Li, Fujun; Chan, Kwong-Yu; Yung, Hoi; Yang, Chunzhen; Ting, Siu Wa

    2013-08-28

    PtRu nanoparticles dispersed in CMK3 mesoporous carbons have been prepared via a CPDM (carbonization over poly-furfuryl alcohol-protected dispersed mixed metals) method. The as-synthesized CMK3 supported PtRu nanoparticles are characterized using tomography and cross-sectional TEM analysis and are compared against those synthesized by the conventional ethylene glycol (EG) method. The atomic ratio of Pt : Ru, which has an essential role on methanol oxidation, is found to be consistent at the nanometer scale. The good dispersion and uniform composition of PtRu nanoparticles result in improved methanol oxidation performance including higher methanol oxidation current and long-term stability. PMID:23827963

  16. Prussian blue mediated amplification combined with signal enhancement of ordered mesoporous carbon for ultrasensitive and specific quantification of metolcarb by a three-dimensional molecularly imprinted electrochemical sensor.

    PubMed

    Yang, Yukun; Cao, Yaoyu; Wang, Xiaomin; Fang, Guozhen; Wang, Shuo

    2015-02-15

    In this work, we presented a three-dimensional (3D) molecularly imprinted electrochemical sensor (MIECS) with novel strategy for ultrasensitive and specific quantification of metolcarb based on prussian blue (PB) mediated amplification combined with signal enhancement of ordered mesoporous carbon. The molecularly imprinted polymers were synthesized by electrochemically induced redox polymerization of para aminobenzoic acid (p-ABA) in the presence of template metolcarb. Ordered mesoporous carbon material (CMK-3) was introduced to enhance the electrochemical response by improving the structure of the modified electrodes and facilitating charge transfer processes of PB which was used as an inherent electrochemical active probe. The modification process for the working electrodes of the MIECS was characterized by scanning electron microscope (SEM) and cyclic voltammetry (CV), and several important parameters controlling the performance of the MIECS were investigated and optimized in detail. The MIECS with 3D structure had the advantages of ease of preparation, high porous surface structure, speedy response, ultrasensitivity, selectivity, reliable stability, good reproducibility and repeatability. Under the optimal conditions, the MIECS offered an excellent current response for metolcarb in the linear response range of 5.0 × 10(-10)-1.0 × 10(-4) mol L(-1) and the limit of detection (LOD) was calculated to be 9.3 × 10 (-11)mol L(-1) (S/N = 3). The proposed MIECS has been successfully applied for the determination of metolcarb in real samples with satisfactory recoveries. Furthermore, the construction route of this ultrasensitive 3D MIECS may provide a guideline for the determination of non-electroactive analytes in environmental control and food safety. PMID:25240126

  17. In situ SAXS study on a new mechanism for mesostructure formation of ordered mesoporous carbons: thermally induced self-assembly.

    PubMed

    Schuster, Jörg; Köhn, Ralf; Döblinger, Markus; Keilbach, Andreas; Amenitsch, Heinz; Bein, Thomas

    2012-07-11

    A new mechanism for mesostructure formation of ordered mesoporous carbons (OMCs) was investigated with in situ small-angle X-ray scattering (SAXS) measurements: thermally induced self-assembly. Unlike the well-established evaporation-induced self-assembly (EISA), the structure formation for organic-organic self-assembly of an oligomeric resol precursor and the block-copolymer templates Pluronic P123 and F127 does not occur during evaporation but only by following a thermopolymerization step at temperatures above 100 °C. The systems investigated here were cubic (Im3m), orthorhombic Fmmm) and 2D-hexagonal (plane group p6mm) mesoporous carbon phases in confined environments, as thin films and within the pores of anodic alumina membranes (AAMs), respectively. The thin films were prepared by spin-coating mixtures of the resol precursor and the surfactants in ethanol followed by thermopolymerization of the precursor oligomers. The carbon phases within the pores of AAMs were made by imbibition of the latter solutions followed by solvent evaporation and thermopolymerization within the solid template. This thermopolymerization step was investigated in detail with in situ grazing incidence small-angle X-ray scattering (GISAXS, for films) and in situ SAXS (for AAMs). It was found that the structural evolution strongly depends on the chosen temperature, which controls both the rate of the mesostructure formation and the spatial dimensions of the resulting mesophase. Therefore the process of structure formation differs significantly from the known EISA process and may rather be viewed as thermally induced self-assembly. The complete process of structure formation, template removal, and shrinkage during carbonization up to 1100 °C was monitored in this in situ SAXS study. PMID:22607051

  18. A stable, reusable, and highly active photosynthetic bioreactor by bio-interfacing an individual cyanobacterium with a mesoporous bilayer nanoshell.

    PubMed

    Jiang, Nan; Yang, Xiao-Yu; Deng, Zhao; Wang, Li; Hu, Zhi-Yi; Tian, Ge; Ying, Guo-Liang; Shen, Ling; Zhang, Ming-Xi; Su, Bao-Lian

    2015-05-01

    An individual cyanobacterium cell is interfaced with a nanoporous biohybrid layer within a mesoporous silica layer. The bio-interface acts as an egg membrane for cell protection and growth of outer shell. The resulting bilayer shell provides efficient functions to create a single cell photosynthetic bioreactor with high stability, reusability, and activity. PMID:25641812

  19. Bottom-Up Catalytic Approach towards Nitrogen-Enriched Mesoporous Carbons/Sulfur Composites for Superior Li-S Cathodes

    PubMed Central

    Sun, Fugen; Wang, Jitong; Chen, Huichao; Qiao, Wenming; Ling, Licheng; Long, Donghui

    2013-01-01

    We demonstrate a sustainable and efficient approach to produce high performance sulfur/carbon composite cathodes via a bottom-up catalytic approach. The selective oxidation of H2S by a nitrogen-enriched mesoporous carbon catalyst can produce elemental sulfur as a by-product which in-situ deposit onto the carbon framework. Due to the metal-free catalytic characteristic and high catalytic selectivity, the resulting sulfur/carbon composites have almost no impurities that thus can be used as cathode materials with compromising battery performance. The layer-by-layer sulfur deposition allows atomic sulfur binding strongly with carbon framework, providing efficient immobilization of sulfur. The nitrogen atoms doped on the carbon framework can increase the surface interactions with polysulfides, leading to the improvement in the trapping of polysulfides. Thus, the composites exhibit a reversible capacity of 939 mAh g−1 after 100 cycles at 0.2 C and an excellent rate capability of 527 mAh g−1 at 5 C after 70 cycles. PMID:24084754

  20. Highly porous activated carbons from resource-recovered Leucaena leucocephala wood as capacitive deionization electrodes.

    PubMed

    Hou, Chia-Hung; Liu, Nei-Ling; Hsi, Hsing-Cheng

    2015-12-01

    Highly porous activated carbons were resource-recovered from Leucaena leucocephala (Lam.) de Wit. wood through combined chemical and physical activation (i.e., KOH etching followed by CO2 activation). This invasive species, which has severely damaged the ecological economics of Taiwan, was used as the precursor for producing high-quality carbonaceous electrodes for capacitive deionization (CDI). Carbonization and activation conditions strongly influenced the structure of chars and activated carbons. The total surface area and pore volume of activated carbons increased with increasing KOH/char ratio and activation time. Overgasification induced a substantial amount of mesopores in the activated carbons. In addition, the electrochemical properties and CDI electrosorptive performance of the activated carbons were evaluated; cyclic voltammetry and galvanostatic charge/discharge measurements revealed a typical capacitive behavior and electrical double layer formation, confirming ion electrosorption in the porous structure. The activated-carbon electrode, which possessed high surface area and both mesopores and micropores, exhibited improved capacitor characteristics and high electrosorptive performance. Highly porous activated carbons derived from waste L. leucocephala were demonstrated to be suitable CDI electrode materials. PMID:26135977

  1. Influences of ureaglycerol mixtures as mixed mesopore-controlling agents on tailoring physicochemical properties and photocatalytic H{sub 2} production activity of solgel-derived mesoporous-assembled TiO{sub 2} nanocrystals

    SciTech Connect

    Sreethawong, Thammanoon; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

    2013-01-15

    Graphical abstract: Display Omitted Highlights: ? Mesoporous-assembled TiO{sub 2} nanocrystals were synthesized by modified solgel process. ? Ureaglycerol mixtures were applied as mixed mesopore-controlling agents. ? Urea and glycerol contents affected physicochemical properties of synthesized TiO{sub 2}. ? Photocatalytic H{sub 2} production activity also depended on urea and glycerol contents. ? 75 mol% urea and 25 mol% glycerol yielded the most photocatalytically active TiO{sub 2}. -- Abstract: In this work, the mesoporous-assembled TiO{sub 2} nanocrystal photocatalysts were successfully synthesized by a solgel process with the aid of ureaglycerol mixtures used as mixed mesopore-controlling agents. The photocatalytic activity of the synthesized mesoporous-assembled TiO{sub 2} nanocrystal photocatalysts was investigated for hydrogen production from the water splitting reaction using methanol as a hole scavenger under UV light irradiation. The synthesized TiO{sub 2} nanocrystal photocatalysts were systematically characterized by TGDTA, N{sub 2} adsorptiondesorption, SEM, high resolution TEM, and XRD analyses. The characterization results showed that the well-controlled contents of urea and glycerol in a ureaglycerol mixture at 75 mol% urea and 25 mol% glycerol resulted in not only the most highly porous network (i.e. the highest specific surface area and total pore volume, and the smallest mean mesopore diameter), but also the smallest crystallite size of the synthesized TiO{sub 2} nanocrystal photocatalyst. The photocatalytic reaction results, hence, revealed a much superior photocatalytic hydrogen production activity of the mesoporous-assembled TiO{sub 2} nanocrystal synthesized with 75 mol% urea and 25 mol% glycerol to the other synthesized TiO{sub 2} nanocrystals, also being much higher than those of the commercially available P-25 TiO{sub 2} and ST-01 TiO{sub 2} powders.

  2. Preparation and characterization of activated carbon from sugarcane bagasse by physical activation with CO2 gas

    NASA Astrophysics Data System (ADS)

    Bachrun, Sutrisno; AyuRizka, Noni; Annisa, SolichaHidayat; Arif, Hidayat

    2016-01-01

    A series of experiments have been conducted to study the effects of different carbonization temperatures (400, 600, and 800oC) on characteristics of porosity in activated carbon derived from carbonized sugarcane bagassechar at activation temperature of 800oC. The results showed that the activated carbon derived from high carbonized temperature of sugarcane bagassechars had higher BET surface area, total volume, micropore volume and yield as compared to the activated carbon derived from low carbonized temperature. The BET surface area, total volume and micropore volume of activated carbon prepared from sugarcane bagassechars obtained at 800oC of carbonized temperature and activation time of 120 min were 661.46m2/g, 0.2455cm3/g and 0.1989cm3/g, respectively. The high carbonization temperature (800oC) generated a highly microporous carbonwith a Type-I nitrogen adsorption isotherm, while the low carbonization temperature (400 and 600oC) generated a mesoporous one with an intermediate between types I and IInitrogen adsorption isotherm.

  3. Gold Incorporated Mesoporous Silica Thin Film Model Surface as a Robust SERS and Catalytically Active Substrate.

    PubMed

    Sunil Sekhar, Anandakumari Chandrasekharan; Vinod, Chathakudath Prabhakaran

    2016-01-01

    Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement. The applicability of these thin films as catalysts as well as a robust SERS active substrate for model catalysis study is tested. Compared to bare silica film our gold incorporated silica, GSM-23F gave an enhancement factor of 10³ for RhB with a laser source 633 nm. The reduction reaction of p-nitrophenol with sodium borohydride from our thin films shows a decrease in peak intensity corresponding to -NO₂ group as time proceeds, confirming the catalytic activity. Such model surfaces can potentially bridge the material gap between a real catalytic system and surface science studies. PMID:27213321

  4. Study on the effect of different acids on the structure and photocatalytic activity of mesoporous titania

    NASA Astrophysics Data System (ADS)

    Ao, Yanhui; Xu, Jingjing; Fu, Degang

    2009-10-01

    Nanocrystalline mesoporous titania was synthesized via a combined sol-gel process with surfactant-assisted templating method using cetyltrimethyl ammonium bromide (CTAB) as the structure-directing agent. The process was catalyzed by different acid (hydrochloric acid, nitric acid, sulfuric acid, or phosphoric acid). The prepared samples were characterized by XRD, TEM, BET and FT-IR. The photocatalytic activity of the samples was determined by degradation of phenol in aqueous solution. Results showed that different acid had different effect on the structure and crystal phase of the samples. The sample adjusted by phosphoric acid showed highest surface area and photocatalytic activity. The formation mechanism of the samples catalyzed by different acid was also discussed.

  5. Synthesis of ruthenium oxide coated ordered mesoporous carbon nanofiber arrays as a catalyst for lithium oxygen battery

    NASA Astrophysics Data System (ADS)

    Guo, Ziyang; Zhou, Dandan; Liu, Haijing; Dong, Xiaoli; Yuan, Shouyi; Yu, Aishui; Wang, Yonggang; Xia, Yongyao

    2015-02-01

    Li-O2 batteries with super-high theoretical energy density are attracting extensive attention. However, the sluggish oxygen reduction/evolution reaction, the huge volume change from O2/Li2O2 conversion and the undesired electrolyte decomposition in cathode limit their performance. Herein we show design and synthesis of RuO2-coated ordered mesoporous carbon nanofiber arrays by using a natural crab shell template as a catalyst for Li-O2 battery, exhibiting several advantage features. First, the ordered mesopores in nanofibers facilitate electrolyte penetration and electron/ion transfer. In addition, the macro-sized voids between the nanofibers provide efficient buffer space for O2/Li2O2 accommodation and improve O2 diffusion. Furthermore, the uniform RuO2-coating layer alleviates undesired electrolyte decomposition and enhances the surface electronic conductivity. As a result, the battery displays high performance, including high capacity (20600 mAh g-1 at a current density of 100 mA g-1), high rate (9750 mAh g-1 at a current density of 1000 mA g-1) and long-life (300 cycles at a fixed capacity of 1000 mAh g-1).

  6. Properties of pyrolytic chars and activated carbons derived from pilot-scale pyrolysis of used tires.

    PubMed

    Li, S Q; Yao, Q; Wen, S E; Chi, Y; Yan, J H

    2005-09-01

    Used tires were pyrolyzed in a pilot-scale quasi-inert rotary kiln. Influences of variables, such as time, temperature, and agent flow, on the activation of obtained char were subsequently investigated in a laboratory-scale fixed bed. Mesoporous pores are found to be dominant in the pore structures of raw char. Brunauer-Emmett-Teller (BET) surfaces of activated chars increased linearly with carbon burnoff. The carbon burnoff of tire char achieved by carbon dioxide (CO2) under otherwise identical conditions was on average 75% of that achieved by steam, but their BET surfaces are almost the same. The proper activation greatly improved the aqueous adsorption of raw char, especially for small molecular adsorbates, for example, phenol from 6 to 51 mg/g. With increasing burnoff, phenol adsorption exhibited a first-stage linear increase followed by a rapid drop after 30% burnoff. Similarly, iodine adsorption first increased linearly, but it held as the burnoff exceeded 40%, which implied that the reduction of iodine adsorption due to decreasing micropores was partially made up by increasing mesopores. Both raw chars and activated chars showed appreciable adsorption capacity of methylene-blue comparable with that of commercial carbons. Thus, tire-derived activated carbons can be used as an excellent mesoporous adsorbent for larger molecular species. PMID:16259427

  7. The Effect of CO2 Activation on the Electrochemical Performance of Coke-Based Activated Carbons for Supercapacitors.

    PubMed

    Lee, Hye-Min; Kim, Hong-Gun; An, Kay-Hyeok; Kim, Byung-Joo

    2015-11-01

    The present study developed electrode materials for supercapacitors by activating coke-based activated carbons with CO2. For the activation reaction, after setting the temperature at 1,000 degrees C, four types of activated carbons were produced, over an activation time of 0-90 minutes and with an interval of 30 minutes as the unit. The electrochemical performance of the activated carbons produced was evaluated to examine the effect of CO2 activation. The surface structure of the porous carbons activated through CO2 activation was observed using a scanning electron microscope (SEM). To determine the N2/77 K isothermal adsorption characteristics, the Brunauer-Emmett-Teller (BET) equation and the Barrett-Joyner-Halenda (BJH) equation were used to analyze the pore characteristics. In addition, charge and discharge tests and cyclic voltammetry (CV) were used to analyze the electrochemical characteristics of the changed pore structure. According to the results of the experiments, the N2 adsorption isotherm curves of the porous carbons produced belonged to Type IV in the International Union of Pore and Applied Chemistry (IUPAC) classification and consisted of micropores and mesopores, and, as the activation of CO2 progressed, micropores decreased and mesopores developed. The specific surface area of the porous carbons activated by CO2 was 1,090-1,180 m2/g and thus showed little change, but those of mesopores were 0.43-0.85 cm3/g, thus increasing considerably. In addition, when the electrochemical characteristics were analyzed, the specific capacity was confirmed to have increased from 13.9 F/g to 18.3 F/g. From these results, the pore characteristics of coke-based activated carbons changed considerably because of CO2 activation, and it was therefore possible to increase the electrochemical characteristics. PMID:26726596

  8. Selective formation of carbon-coated, metastable amorphous ZnSnO₃ nanocubes containing mesopores for use as high-capacity lithium-ion battery.

    PubMed

    Han, Fei; Li, Wen-Cui; Lei, Cheng; He, Bin; Oshida, Kyoichi; Lu, An-Hui

    2014-07-01

    Mesoporous and amorphous ZnSnO3 nanocubes of ~37 nm size coated with a thin porous carbon layer have been prepared using monodisperse ZnSn(OH)6 as the active precursor and low-temperature synthesized polydopamine as the carbon precursor. The small single nanocubes cross-link with each other to form a continuous conductive framework and interconnected porous channels with macropores of 74 nm width. Because of its multi-featured nanostructure, this material exhibits greatly enhanced integration of reversible alloying/de-alloying (i.e., transformation of Li(4.4)Sn and LiZn to Sn and Zn) and conversion (i.e., oxidation of Sn and Zn to ZnSnO3) reaction processes with an extremely high capacity of 1060 mA h g(-1) for up to 100 cycles. A high reversible capacity of 650 and 380 mA h g(-1) can also be delivered at rates of 2 and 3 A g(-1), respectively. This excellent electrochemical performance is attributed to the small particle size, well-developed mesoporosity, the amorphous nature of the ZnSnO3 and the continuous conductive framework produced by the interconnected carbon layers. PMID:24616322

  9. Sulfur-functionalized mesoporous carbons as sulfur hosts in Li-S batteries: increasing the affinity of polysulfide intermediates to enhance performance.

    PubMed

    See, Kimberly A; Jun, Young-Si; Gerbec, Jeffrey A; Sprafke, Johannes K; Wudl, Fred; Stucky, Galen D; Seshadri, Ram

    2014-07-23

    The Li-S system offers a tantalizing battery for electric vehicles and renewable energy storage due to its high theoretical capacity of 1675 mAh g(-1) and its employment of abundant and available materials. One major challenge in this system stems from the formation of soluble polysulfides during the reduction of S8, the active cathode material, during discharge. The ability to deploy this system hinges on the ability to control the behavior of these polysulfides by containing them in the cathode and allowing for further redox. Here, we exploit the high surface areas and good electrical conductivity of mesoporous carbons (MC) to achieve high sulfur utilization while functionalizing the MC with sulfur (S-MC) in order to modify the surface chemistry and attract polysulfides to the carbon material. S-MC materials show enhanced capacity and cyclability trending as a function of sulfur functionality, specifically a 50% enhancement in discharge capacity is observed at high cycles (60-100 cycles). Impedance spectroscopy suggests that the S-MC materials exhibit a lower charge-transfer resistance compared with MC materials which allows for more efficient electrochemistry with species in solution at the cathode. Isothermal titration calorimetry shows that the change in surface chemistry from unfunctionalized to S-functionalized carbons results in an increased affinity of the polysulfide intermediates for the S-MC materials, which is the likely cause for enhanced cyclability. PMID:24524220

  10. In-Situ Observation of Solid Electrolyte Interphase Formation in Ordered Mesoporous Hard Carbon by Small-Angle Neutron Scattering

    SciTech Connect

    Bridges, Craig A; Paranthaman, Mariappan Parans; Sun, Xiao-Guang; Zhao, Jinkui; Dai, Sheng

    2012-01-01

    The aim of this work was to better understand the electrochemical processes occurring during the cycling of a lithium-ion half-cell containing ordered mesoporous hard carbon using time-resolved in situ small-angle neutron scattering (SANS). Utilizing electrolytes containing mixtures of deuterated (2H) and non-deuterated (1H) carbonates, we have addressed the challenging task of monitoring the formation and evolution of the solid-electrolyte interphase (SEI) layer. An evolution occurs in the SEI layer during discharge from a composition dominated by a higher scattering length density (SLD) lithium salt, to a lower SLD lithium salt for the ethylene carbonate/dimethyl carbonate (EC/DMC) mixture employed. By comparing half-cells containing different solvent deuteration levels, we show that it is possible to observe both SEI formation and lithium intercalation occurring concurrently at the low voltage region in which lithium intercalates into the hard carbon. These results demonstrate that SANS can be employed to monitor complicated electrochemical processes occurring in rechargeable batteries, in a manner that simultaneously provides information on the composition and microstructure of the electrode.

  11. Thermally decomposed mesoporous Nickel Iron hydrotalcite: an active solid-base catalyst for solvent-free Knoevenagel condensation.

    PubMed

    Dumbre, Deepa K; Mozammel, Tibra; Selvakannan, Pr; Hamid, Sharifah Bee Abdul; Choudhary, Vasant R; Bhargava, Suresh K

    2015-03-01

    Thermal decomposition of co-precipitated Ni-Fe-HT materials led to the formation a mesoporous Ni-Fe-HT catalyst and we have demonstrated here its active role as solid and active catalyst for the Knoevenagel condensation reaction of various aldehydes with active methylene compounds (R-CH2-CN, where R=CN or CO2Et). High product yields are obtained at moderate temperature under solvent-free conditions and the catalyst can be easily separated from the reaction mixture, simply by filtration and reused several times without a significant loss of its activity. Since these mesoporous metal oxides derived from the NiFe hydrotalcites, their basicity mediated abstraction of the acidic protons from the active methylene compounds was responsible for their catalytic activity under solvent-free conditions. PMID:25490562

  12. Studies of adsorption equilibria and kinetics in the systems: Aqueous solution of dyes-mesoporous carbons

    NASA Astrophysics Data System (ADS)

    Derylo-Marczewska, A.; Marczewski, A. W.; Winter, Sz.; Sternik, D.

    2010-06-01

    Two carbonaceous materials were synthesized by using the method of impregnation of mesoporous silicas obtained by applying the Pluronic copolymers as pore-creating agents. The isotherms of adsorption of methylene blue and methyl orange from aqueous solutions were measured by the static method. The profiles of adsorbate concentration change in time were obtained from the UV-vis spectra. The adsorption isotherms and kinetic dependence were discussed in the terms of theory of adsorption on heterogeneous surfaces.

  13. Tailored Fabrication of Thoroughly Mesoporous BiVO4 Nanofibers and Their Visible-Light Photocatalytic Activities.

    PubMed

    Liu, Huabing; Hou, Huilin; Gao, Fengmei; Yao, Xiaohong; Yang, Weiyou

    2016-01-27

    Bismuth vanadate (BiVO4) is considered as a potentially attractive candidate for the O2 evolution and photodegradation of organic pollutants. In an effort to develop visible-light-driven photocatalysts with high activities, the thoroughly mesoporous BiVO4 nanofibers were fabricated via a foaming-assisted electrospinning strategy. It was found that the introduced foaming agent of diisopropyl azodiformate within the solutions plays a crucial role on the formation of thoroughly mesoporous BiVO4 nanofibers, making their growth tunable. The obtained mesoporous BiVO4 nanofibers possess well-defined one-dimensional mesoporous architectures with high purity in their morphology and a surface area of 22.5 m(2)/g, which is ∼4 times that of conventional solid counterparts (5.8 m(2)/g). Accordingly, they exhibit much higher efficient photocatalytic activities toward the degradation of rhodamine B under visible-light irradiation, which is 3 times that of conventional solid counterparts, suggesting their promising application as novel and efficient photocatalysts for water purification. PMID:26728095

  14. Importance of structural and chemical heterogeneity of activated carbon surfaces for adsorption of dibenzothiophene

    SciTech Connect

    Ania, C.O.; Bandosz, T.J.

    2005-08-16

    The performance of various activated carbons obtained from different carbon precursors (i.e., plastic waste, coal, and wood) as adsorbents for the desulfurization of liquid hydrocarbon fuels was evaluated. To increase surface heterogeneity, the carbon surface was modified by oxidation with ammonium persulfate. The results showed the importance of activated carbon pore sizes and surface chemistry for the adsorption of dibenzothiophene (DBT) from liquid phase. Adsorption of DBT on activated carbons is governed by two types of contributions: physical and chemical interactions. The former include dispersive interactions in the microporous network of the carbons. While the volume of micropores governs the amount physisorbed, mesopores control the kinetics of the process. On the other hand, introduction of surface functional groups enhances the performance of the activated carbons as a result of specific interactions between the acidic centers of the carbon and the basic structure of DBT molecule as well as sulfur-sulfur interactions.

  15. Optimization of fuel cell membrane electrode assemblies for transition metal ion-chelating ordered mesoporous carbon cathode catalysts a

    NASA Astrophysics Data System (ADS)

    Dombrovskis, Johanna K.; Prestel, Cathrin; Palmqvist, Anders E. C.

    2014-12-01

    Transition metal ion-chelating ordered mesoporous carbon (TM-OMC) materials were recently shown to be efficient polymer electrolyte membrane fuel cell (PEMFC) catalysts. The structure and properties of these catalysts are largely different from conventional catalyst materials, thus rendering membrane electrode assembly (MEA) preparation parameters developed for conventional catalysts not useful for applications of TM-OMC catalysts. This necessitates development of a methodology to incorporate TM-OMC catalysts in the MEA. Here, an efficient method for MEA preparation using TM-OMC catalyst materials for PEMFC is developed including effects of catalyst/ionomer loading and catalyst/ionomer-mixing and application procedures. An optimized protocol for MEA preparation using TM-OMC catalysts is described.

  16. Bifunctional Mesoporous Carbon Nitride: Highly Efficient Enzyme-like Catalyst for One-pot Deacetalization-Knoevenagel Reaction

    PubMed Central

    Zhong, Lin; Anand, Chokkalingam; Lakhi, Kripal Singh; Lawrence, Geoffrey; Vinu, Ajayan

    2015-01-01

    Recently, mesoporous carbon nitride (MCN) has aroused extensive interest for its potential applications in organocatalysis, photo- and electrochemistry and CO2 capture. However, further surface functionalization of MCN for advanced nanomaterials and catalysis still remains very challenging. Here we show that acidic carboxyl groups can be smoothly introduced onto the surface of well-ordered MCN without annihilation between the introduced acid groups and MCN’s inherent basic groups through a facile UV light oxidation method. The functionalization generates a novel bifunctional nanocatalyst which offers an enzyme-like catalytic performance in the one-pot deacetalization-Knoevenagel reaction of benzaldehyde dimethylacetal and malononitrile with 100% conversion and more than 99% selectivity due to the cooperative catalysis between the acid and base groups separated on the surface of the catalyst. The results provide a general method to create multifunctional nanomaterials and open new opportunities for the development of high efficient catalyst for green organic synthesis. PMID:26243180

  17. Low temperature synthesis and visible light driven photocatalytic activity of highly crystalline mesoporous TiO2 particles.

    PubMed

    Gujar, Tanaji P; Anand, Chokkalingam; Shinde, Vaishali R; Ye, Jinhua; Ariga, Katsuhiko; Vinu, Ajayan

    2010-12-01

    Mesoporous TiO2 powder materials with a high crystallinity have been prepared by evaporation induced self assembly (EISA) process using titanium tetraisopropoxide (TTIP) and pluronic P123 surfactant (EO20PO70EO20) as titanium source and structure-directing reagent, respectively. The prepared materials were characterized by low and wide-angle X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), optical absorption, and N2 adsorption-desorption experiments. The crystallinity of the materials was controlled by varying the calcination temperature. The resulting TiO2 materials showed highly crystalline structure with uniform particle size which increases from 11.8 to 23.8 nm with increasing the calcination temperature from 400 to 600 degrees C, respectively, whereas the specific surface area decreases from 125 to 40 m2/g. TEM and XRD results revealed that the calcination temperature of 600 degrees C is the best condition to obtain highly crystalline mesoporous TiO2. The photocatalytic activity of the TiO2 mesoporous materials with different crystallinity and textural parameters has been studied in the decomposition of methylene blue (MB) dye molecules under visible light irradiation. Among the mesoporous TiO2 materials studied, the material with the highest crystallinity, prepared at 600 degrees C, showed the best photocatalytic performance in the decomposition of MB under visible light in a short time. PMID:21121305

  18. Enhanced removal of Cd(II) and Pb(II) by composites of mesoporous carbon stabilized alumina

    NASA Astrophysics Data System (ADS)

    Yang, Weichun; Tang, Qiongzhi; Wei, Jingmiao; Ran, Yajun; Chai, Liyuan; Wang, Haiying

    2016-04-01

    A novel adsorbent of mesoporous carbon stabilized alumina (MC/Al2O3) was synthesized through one-pot hard-templating method. The adsorption potential of MC/Al2O3 for Cd(II) and Pb(II) from aqueous solution was investigated compared with the mesoporous carbon. The results indicated the MC/Al2O3 showed excellent performance for Cd(II) and Pb(II) removal, the adsorption capacity reached 49.98 mg g-1 for Cd(II) with initial concentration of 50 mg L-1 and reached 235.57 mg g-1 for Pb(II) with initial concentration of 250 mg L-1, respectively. The kinetics data of Cd(II) adsorption demonstrated that the Cd(II) adsorption rate was fast, and the removal efficiencies with initial concentration of 10 and 50 mg L-1 can reach up 99% within 5 and 20 min, respectively. The pseudo-second-order kinetic model could describe the kinetics of Cd(II) adsorption well, indicating the chemical reaction was the rate-controlling step. The mechanism for Cd(II) and Pb(II) adsorption by MC/Al2O3 was investigated by X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared spectroscopy (FTIR), and the results indicated that the excellent performance for Cd(II) and Pb(II) adsorption of MC/Al2O3 was mainly attributed to its high surface area and the special functional groups of hydroxy-aluminum, hydroxyl, carboxylic through the formation of strong surface complexation or ion-exchange. It was concluded that MC/Al2O3 can be recognized as an effective adsorbent for removal of Cd(II) and Pb(II) in aqueous solution.

  19. Three-Dimensional Network of N-Doped Carbon Ultrathin Nanosheets with Closely Packed Mesopores: Controllable Synthesis and Application in Electrochemical Energy Storage.

    PubMed

    Zhu, Shan; Li, Jiajun; Ma, Liying; Guo, Lichao; Li, Qunying; He, Chunnian; Liu, Enzuo; He, Fang; Shi, Chunsheng; Zhao, Naiqin

    2016-05-11

    A flexible one-pot strategy for fabricating a 3D network of nitrogen-doped (N-doped) carbon ultrathin nanosheets with closely packed mesopores (N-MCN) via an in situ template method is reported in this research. The self-assembly soluble salts (NaCl and Na2SiO3) serve as hierarchical templates and support the formation of a 3D glucose-urea complex. The organic complex is heat-treated to obtain a 3D N-doped carbon network constructed by mesoporous nanosheets. Especially, both the mesoporous structure and doping content can be easily tuned by adjusting the ratio of raw materials. The large specific surface area and closely packed mesopores facilitate the lithium ion intercalation/deintercalation accordingly. Besides, the nitrogen content improves the lithium storage ability and capacitive properties. Due to the synergistic effect of hierarchical structure and heteroatom composition, the 3D N-MCN shows excellent characteristics as the electrode of a lithium ion battery and supercapacitor, such as ultrahigh reversible storage capacity (1222 mAh g(-1) at 0.1 A g(-1)), stable long cycle performance at high current density (600 cycles at 2 A g(-1)), and high capacitive properties (225 F g(-1) at 1 A g(-1) and 163 F g(-1) at 50 A g(-1)). PMID:27093444

  20. Gold nanoparticles supported on mesoporous silica: origin of high activity and role of Au NPs in selective oxidation of cyclohexane.

    PubMed

    Wu, Pingping; Bai, Peng; Yan, Zifeng; Zhao, George X S

    2016-01-01

    Homogeneous immobilization of gold nanoparticles (Au NPs) on mesoporous silica has been achieved by using a one-pot synthesis method in the presence of organosilane mercapto-propyl-trimethoxysilane (MPTMS). The resultant Au NPs exhibited an excellent catalytic activity in the solvent-free selective oxidation of cyclohexane using molecular oxygen. By establishing the structure-performance relationship, the origin of the high activity of mesoporous supported Au catalyst was identified to be due to the presence of low-coordinated Au (0) sites with high dispersion. Au NPs were confirmed to play a critical role in the catalytic oxidation of cyclohexane by promoting the activation of O2 molecules and accelerating the formation of surface-active oxygen species. PMID:26729288

  1. Gold nanoparticles supported on mesoporous silica: origin of high activity and role of Au NPs in selective oxidation of cyclohexane

    NASA Astrophysics Data System (ADS)

    Wu, Pingping; Bai, Peng; Yan, Zifeng; Zhao, George X. S.

    2016-01-01

    Homogeneous immobilization of gold nanoparticles (Au NPs) on mesoporous silica has been achieved by using a one-pot synthesis method in the presence of organosilane mercapto-propyl-trimethoxysilane (MPTMS). The resultant Au NPs exhibited an excellent catalytic activity in the solvent-free selective oxidation of cyclohexane using molecular oxygen. By establishing the structure-performance relationship, the origin of the high activity of mesoporous supported Au catalyst was identified to be due to the presence of low-coordinated Au (0) sites with high dispersion. Au NPs were confirmed to play a critical role in the catalytic oxidation of cyclohexane by promoting the activation of O2 molecules and accelerating the formation of surface-active oxygen species.

  2. Gold nanoparticles supported on mesoporous silica: origin of high activity and role of Au NPs in selective oxidation of cyclohexane

    PubMed Central

    Wu, Pingping; Bai, Peng; Yan, Zifeng; Zhao, George X. S.

    2016-01-01

    Homogeneous immobilization of gold nanoparticles (Au NPs) on mesoporous silica has been achieved by using a one-pot synthesis method in the presence of organosilane mercapto-propyl-trimethoxysilane (MPTMS). The resultant Au NPs exhibited an excellent catalytic activity in the solvent-free selective oxidation of cyclohexane using molecular oxygen. By establishing the structure-performance relationship, the origin of the high activity of mesoporous supported Au catalyst was identified to be due to the presence of low-coordinated Au (0) sites with high dispersion. Au NPs were confirmed to play a critical role in the catalytic oxidation of cyclohexane by promoting the activation of O2 molecules and accelerating the formation of surface-active oxygen species. PMID:26729288

  3. High-yield harvest of nanofibers/mesoporous carbon composite by pyrolysis of waste biomass and its application for high durability electrochemical energy storage.

    PubMed

    Liu, Wu-Jun; Tian, Ke; He, Yan-Rong; Jiang, Hong; Yu, Han-Qing

    2014-12-01

    Disposal and recycling of the large scale biomass waste is of great concern. Themochemically converting the waste biomass to functional carbon nanomaterials and bio-oil is an environmentally friendly apporach by reducing greenhouse gas emissions and air pollution caused by open burning. In this work, we reported a scalable, "green" method for the synthesis of the nanofibers/mesoporous carbon composites through pyrolysis of the Fe(III)-preloaded biomass, which is controllable by adjustment of temperature and additive of catalyst. It is found that the coupled catalytic action of both Fe and Cl species is able to effectively catalyze the growth of the carbon nanofibers on the mesoporous carbon and form magnetic nanofibers/mesoporous carbon composites (M-NMCCs). The mechanism for the growth of the nanofibers is proposed as an in situ vapor deposition process, and confirmed by the XRD and SEM results. M-NMCCs can be directly used as electrode materials for electrochemical energy storage without further separation, and exhibit favorable energy storage performance with high EDLC capacitance, good retention capability, and excellent stability and durability (more than 98% capacitance retention after 10,000 cycles). Considering that biomass is a naturally abundant and renewable resource (over billions tons biomass produced every year globally) and pyrolysis is a proven technique, M-NMCCs can be easily produced at large scale and become a sustainable and reliable resource for clean energy storage. PMID:25372400

  4. Effects of pyrolysis conditions on the porous structure construction of mesoporous charred carbon from used cigarette filters

    NASA Astrophysics Data System (ADS)

    Masoudi Soltani, Salman; Yazdi, Sara Kazemi; Hosseini, Soraya

    2013-05-01

    One-step pyrolysis was applied to synthesize mesoporous charred carbon from used cigarette filters. Proximate analysis suggested that cigarette filters are decent carbon precursors due to their moderate carbon (around 11 %) and low ash (around 0.1 %) contents. To investigate the effects of pyrolysis parameters on porous surface area, a full factorial design of experiment including heating rate, soaking time and pyrolysis temperature was used with each factor at three levels. The analysis of variance revealed that the temperature and heating rate had the most significant effects on total surface area of the synthesized carbon. Response surface model (RSM) was applied to best fit a surface through the experimental data. It was seen that the quadratic RSM model with a reasonable R 2 value of 63 % was the best developed model. The maximum BET surface area (597 m2/g) was reached at a pyrolysis temperature of 900 °C when the precursor was heated at 5 °C/min and hold at this temperature for 3 h. The produced N2 adsorption-desorption isotherm showed a certain degree of mesoporosity in the charred carbon with an average pore size of 3.32 nm calculated by Barrett-Joyner-Halenda method. Scanning electron microscopy also showed the presence of macroporosity on the charred carbon surface. Fourier transform infrared spectroscopy revealed the presence of acidic surface functional groups such as carboxyl and phenol which were accordingly confirmed by Boehm titration. In addition, Boehm titration showed that the produced carbon's surface was more acidic than basic in nature.

  5. Effects of pyrolysis conditions on the porous structure construction of mesoporous charred carbon from used cigarette filters

    NASA Astrophysics Data System (ADS)

    Masoudi Soltani, Salman; Yazdi, Sara Kazemi; Hosseini, Soraya

    2014-06-01

    One-step pyrolysis was applied to synthesize mesoporous charred carbon from used cigarette filters. Proximate analysis suggested that cigarette filters are decent carbon precursors due to their moderate carbon (around 11 %) and low ash (around 0.1 %) contents. To investigate the effects of pyrolysis parameters on porous surface area, a full factorial design of experiment including heating rate, soaking time and pyrolysis temperature was used with each factor at three levels. The analysis of variance revealed that the temperature and heating rate had the most significant effects on total surface area of the synthesized carbon. Response surface model (RSM) was applied to best fit a surface through the experimental data. It was seen that the quadratic RSM model with a reasonable R 2 value of 63 % was the best developed model. The maximum BET surface area (597 m2/g) was reached at a pyrolysis temperature of 900 °C when the precursor was heated at 5 °C/min and hold at this temperature for 3 h. The produced N2 adsorption-desorption isotherm showed a certain degree of mesoporosity in the charred carbon with an average pore size of 3.32 nm calculated by Barrett-Joyner-Halenda method. Scanning electron microscopy also showed the presence of macroporosity on the charred carbon surface. Fourier transform infrared spectroscopy revealed the presence of acidic surface functional groups such as carboxyl and phenol which were accordingly confirmed by Boehm titration. In addition, Boehm titration showed that the produced carbon's surface was more acidic than basic in nature.

  6. Adsorption of aqueous metal ions on cattle-manure-compost based activated carbons.

    PubMed

    Zaini, Muhammad Abbas Ahmad; Okayama, Reiko; Machida, Motoi

    2009-10-30

    The objective of this study is to examine the suitability and performance of cattle-manure-compost (CMC) based activated carbons in removing heavy metal ions from aqueous solution. The influence of ZnCl(2) activation ratios and solution pH on the removal of Cu(II) and Pb(II) were studied. Pore texture, available surface functional groups, pH of point zero charge (pH(PZC)), thermogravimetric analysis and elemental compositions were obtained to characterize the activated carbons. Batch adsorption technique was used to determine the metal-binding ability of activated carbons. The equilibrium data were characterized using Langmuir, Freundlich and Redlich-Peterson models. It was found that the uptake of aqueous metal ions by activated carbons could be well described by Langmuir equation. It is suggested that the increase of surface area and mesopore ratio as a result of increasing activation ratios favored the removal of Cu(II), while activated carbon rich in acidic groups showed selective adsorption towards Pb(II). The preferable removal of Cu(II) over Pb(II) could be due to the rich nitrogen content as well as the higher mesoporous surface area in the CMC activated carbons. The impregnated CMC activated carbons also showed a better performance for Cu(II) removal at varying solution pH than Filtrasorb 400 (F400), while a similar performance was observed for Pb(II) removal. PMID:19541418

  7. Enhancing capacitive deionization performance of electrospun activated carbon nanofibers by coupling with carbon nanotubes.

    PubMed

    Dong, Qiang; Wang, Gang; Wu, Tingting; Peng, Senpei; Qiu, Jieshan

    2015-05-15

    Capacitive deionization (CDI) is an alternative, effective and environmentally friendly technology for desalination of brackish water. The performance of the CDI device is highly determined by the electrode materials. In this paper, a composite of carbon nanotubes (CNTs) embedded in activated carbon nanofiber (ACF) was prepared by a direct co-electrospinning way and subsequent CO2 activation. The introduction of CNTs can greatly improve the conductivity while the CO2-mediated activation can render the final product with high porosity. As such, the hybrid structure can provide an excellent storage space and pathways for ion adsorption and conduction. When evaluated as electrode materials for CDI, the as-prepared CNT/ACF composites with higher electrical conductivity and mesopore ratios exhibited higher electrosorption capacity and good regeneration performance in comparison with the pure ACF. PMID:25595622

  8. Dewatering Peat With Activated Carbon

    NASA Technical Reports Server (NTRS)

    Rohatgi, N. K.

    1984-01-01

    Proposed process produces enough gas and carbon to sustain itself. In proposed process peat slurry is dewatered to approximately 40 percent moisture content by mixing slurry with activated carbon and filtering with solid/liquid separation techniques.

  9. Improved performance of electrodes based on carbonized olive stones/S composites by impregnating with mesoporous TiO2 for advanced Lisbnd S batteries

    NASA Astrophysics Data System (ADS)

    Moreno, Noelia; Caballero, Álvaro; Morales, Julián; Rodríguez-Castellón, Enrique

    2016-05-01

    Carbons obtained from biomass have attracted a lot of attention for use as electrodes for Li-ion batteries. Less attention has been paid to their use in Lisbnd S batteries in spite of the higher energy densities. Here, we optimized the electrochemical properties of an activated carbon (OSAC) obtained from olive stones with the help of mesoporous TiO2. The OSAC@TiO2/S hybrid composite exhibited improved electrochemical performance compared with the OSAC/S composite. The presence of TiO2 increased the delivered capacity of the cell by more than 60%, and the rate capability was notably improved. The cell could operate at current densities of 3350 mA g-1 (2 C), releasing an average capacity of 500 mAh g-1 with a coulombic efficiency close to 100%. This improvement in the electrochemical performance is attributed to the sorbent properties of TiO2 towards Li polysulfides and its facility to insert Li, which enhances the electronic and ionic conductivity of the hybrid composite.

  10. One-step preparation of carbon nanotubes doped mesoporous birnessite K2Mn4O9 achieving 77% of theoretical capacitance by a facile redox reaction

    NASA Astrophysics Data System (ADS)

    Kang, Litao; Li, Peiyang; Tao, Keyu; Wang, Xiaomin; Liang, Wei; Gao, Yanfeng

    2016-01-01

    A facile, scalable and cost-efficient redox reaction is developed to prepare micro-powders of a quasi-crystallised, mesoporous birnessite-type manganese oxide, K2Mn4O9. In 1 M KOH electrolyte, the K2Mn4O9 powder shows a high specific capacitance of 754 F g-1 at 1 A g-1 (calculated with the net weight of K2Mn4O9 micro-powder only). Meanwhile, the electrode retains 91% of its initial capacitance after 5000 cycles at a high current density of 5 A g-1. By simply adding carbon nanotubes (CNTs) into the reaction system, the specific capacitances of as-prepared K2Mn4O9/CNTs composites are further increased to 929 and 1055 F g-1 at 1 A g-1 in 1 and 6 M KOH electrolyte (corresponding to 69 and 77% of the theoretical capacitance of MnO2), or 600 and 674 F g-1 at 5 A g-1, respectively. Significantly, a maximum energy density of 62 Wh kg-1 at a power density of 852 W kg-1 could be achieved based on a K2Mn4O9/CNTs//activated carbon asymmetric supercapacitor (ASC). At the same time, the ASC device exhibits a decent long cycle life with 85% specific capacitance retained after 1000 cycles, suggesting its wide application potential in low-cost high energy density storage systems.

  11. Application of mesoporous carbon as a solid-phase microextraction fiber coating for the extraction of volatile aromatic compounds.

    PubMed

    Zhang, Xi; Zang, Xiaohuan; Zhang, Guijiang; Wang, Chun; Wang, Zhi

    2015-08-01

    A mesoporous carbon was fabricated using MCM-41 as a template and sucrose as a carbon source. The carbon material was coated on stainless-steel wires by using the sol-gel technique. The prepared solid-phase microextraction fiber was used for the extraction of five volatile aromatic compounds (chlorobenzene, ethylbenzene, o-xylene, bromobenzene, and 4-chlorotoluene) from tea beverage samples (red tea and green tea) prior to gas chromatography with mass spectrometric detection. The main experimental parameters affecting the extraction of the volatile aromatic compounds by the fiber, including the extraction time, sample volume, extraction temperature, salt addition, and desorption conditions, were investigated. The linearity was observed in the range from 0.1 to 10.0 μg/L with the correlation coefficients (r) ranging from 0.9923 to 0.9982 and the limits of detection were less than 10.0 ng/L. The recoveries of the volatile aromatic compounds by the method from tea beverage samples at spiking levels of 1.0 and 10.0 μg/L ranged from 73.1 to 99.1%. PMID:26041569

  12. 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.

  13. A general chelate-assisted co-assembly to metallic nanoparticles-incorporated ordered mesoporous carbon catalysts for Fischer-Tropsch synthesis.

    PubMed

    Sun, Zhenkun; Sun, Bo; Qiao, Minghua; Wei, Jing; Yue, Qin; Wang, Chun; Deng, Yonghui; Kaliaguine, Serge; Zhao, Dongyuan

    2012-10-24

    The organization of different nano objects with tunable sizes, morphologies, and functions into integrated nanostructures is critical to the development of novel nanosystems that display high performances in sensing, catalysis, and so on. Herein, using acetylacetone as a chelating agent, phenolic resol as a carbon source, metal nitrates as metal sources, and amphiphilic copolymers as a template, we demonstrate a chelate-assisted multicomponent coassembly method to synthesize ordered mesoporous carbon with uniform metal-containing nanoparticles. The obtained nanocomposites have a 2-D hexagonally arranged pore structure, uniform pore size (~4.0 nm), high surface area (~500 m(2)/g), moderate pore volume (~0.30 cm(3)/g), uniform and highly dispersed Fe(2)O(3) nanoparticles, and constant Fe(2)O(3) contents around 10 wt %. By adjusting acetylacetone amount, the size of Fe(2)O(3) nanoparticles is readily tunable from 8.3 to 22.1 nm. More importantly, it is found that the metal-containing nanoparticles are partially embedded in the carbon framework with the remaining part exposed in the mesopore channels. This unique semiexposure structure not only provides an excellent confinement effect and exposed surface for catalysis but also helps to tightly trap the nanoparticles and prevent aggregating during catalysis. Fischer-Tropsch synthesis results show that as the size of iron nanoparticles decreases, the mesoporous Fe-carbon nanocomposites exhibit significantly improved catalytic performances with C(5+) selectivity up to 68%, much better than any reported promoter-free Fe-based catalysts due to the unique semiexposure morphology of metal-containing nanoparticles confined in the mesoporous carbon matrix. PMID:23020275

  14. Peroxidase-like activity of mesoporous silica encapsulated Pt nanoparticle and its application in colorimetric immunoassay.

    PubMed

    Wang, Zhifei; Yang, Xia; Yang, Jingjing; Jiang, Yanyun; He, Nongyue

    2015-03-01

    Nanomaterial-based artificial enzymes have received great attention in recent year due to their potential application in immunoassay techniques. However, such potential is usually limited by poor dispersion stability or low catalytic activity induced by the capping agent essentially required in the synthesis. In an attempt to address these challenges, here, we studied the novel Pt nanoparticles (NPs) based peroxidase-like mimic by encapsulating Pt NP in mesoporous silica (Pt@mSiO2 NPs). Compared with other nanomaterial-based artificial enzymes, the obtained Pt@mSiO2 NPs not only exhibit high peroxidase-like activity but also have good dispersion stability in buffer saline solution when grafted with spacer PEG. Results show that when the thickness of silica shell is about 9 nm the resulting Pt@mSiO2 NPs exhibit the catalytic activity similar to that of Pt NPs, which is approximately 26 times higher than that of Fe3O4 NPs (in terms of Kcat for H2O2). Due to the protection of silica shell, the subsequent surface modification with antibody has little effect on their catalytic activity. The analytical performance of this system in detecting hCG shows that after 5 min incubation the limit of detection can reach 10 ng mL(-1) and dynamic linear working range is 5-200 ng mL(-1). Our findings pave the way for design and development of novel artificial enzyme labeling. PMID:25682428

  15. Thermo-catalytic decomposition of formaldehyde: a novel approach to produce mesoporous ZnO for enhanced photocatalytic activities

    NASA Astrophysics Data System (ADS)

    Lei, Jian F.; Li, Li B.; Du, Kai; Ni, Jing; Zhang, Shao F.; Zhao, Ling Z.

    2014-06-01

    A novel method, thermo-catalytic decomposition of formaldehyde, is used to synthesize mesoporous ZnO crystals with enhanced photocatalytic activities. The mechanism of the mesoporous formation is investigated by synthesizing a series of samples at various systems and characterizing them with FT-IR, EDS, XRD, SEM, and TEM. The results show that formaldehyde can be adsorbed on the crystal planes of ZnO during the crystal growth and can then be catalytically decomposed into CO, CO2 and H2 during a sintering process. Because of the formation and the escape of these gases, which act as templates, the crystalline particles of ZnO are forced to rearrange consistently, and pores are formed in the internal crystal. Also, porous TiO2 crystals have been obtained via the same approach. Photocatalytic tests indicate that a porous ZnO crystal has higher activity than that of a nonporous one.

  16. Activated carbon from vetiver roots: gas and liquid adsorption studies.

    PubMed

    Gaspard, S; Altenor, S; Dawson, E A; Barnes, P A; Ouensanga, A

    2007-06-01

    Large quantities of lignocellulosic residues result from the industrial production of essential oil from vetiver grass (Vetiveria zizanioides) roots. These residues could be used for the production of activated carbon. The yield of char obtained after vetiver roots pyrolysis follows an equation recently developed [A. Ouensanga, L. Largitte, M.A. Arsene, The dependence of char yield on the amounts of components in precursors for pyrolysed tropical fruit stones and seeds, Micropor. Mesopor. Mater. 59 (2003) 85-91]. The N(2) adsorption isotherm follows either the Freundlich law K(F)P(alpha) which is the small alpha equation limit of a Weibull shaped isotherm or the classical BET isotherm. The surface area of the activated carbons are determined using the BET method. The K(F) value is proportional to the BET surface area. The alpha value increases slightly when the burn-off increases and also when there is a clear increase in the micropore distribution width. PMID:17092643

  17. Synthesis and photocatalytic activity for water-splitting reaction of nanocrystalline mesoporous titania prepared by hydrothermal method

    SciTech Connect

    Jitputti, Jaturong; Pavasupree, Sorapong; Suzuki, Yoshikazu; Yoshikawa, Susumu

    2007-05-15

    Nanocrystalline mesoporous TiO{sub 2} was synthesized by hydrothermal method using titanium butoxide as starting material. XRD, SEM, and TEM analyses revealed that the synthesized TiO{sub 2} had anatase structure with crystalline size of about 8 nm. Moreover, the synthesized titania possessed a narrow pore size distribution with average pore diameter and high specific surface area of 215 m{sup 2}/g. The photocatalytic activity of synthesized TiO{sub 2} was evaluated with photocatalytic H{sub 2} production from water-splitting reaction. The photocatalytic activity of synthesized TiO{sub 2} treated with appropriate calcination temperature was considerably higher than that of commercial TiO{sub 2} (Ishihara ST-01). The utilization of mesoporous TiO{sub 2} photocatalyst with high crystallinity of anatase phase promoted great H{sub 2} production. Furthermore, the reaction temperature significantly influences the water-splitting reaction. - Graphical abstract: Nanocrystalline mesoporous TiO{sub 2} was synthesized by hydrothermal method. The physical properties of the synthesized TiO{sub 2} were thoroughly studied in relation to its photocatalytic activity for H{sub 2} evolution from water-splitting reaction. It was found that the photocatalytic activity of synthesized TiO{sub 2} treated with appropriate calcination temperature was considerably higher than that of commercial TiO{sub 2} (Ishihara ST-01)

  18. Sulfur-infiltrated graphene-backboned mesoporous carbon nanosheets with a conductive polymer coating for long-life lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Dong, Yanfeng; Liu, Shaohong; Wang, Zhiyu; Liu, Yang; Zhao, Zongbin; Qiu, Jieshan

    2015-04-01

    Sandwich-type, two-dimensional hybrid nanosheets were fabricated by the infiltration of nanosized sulfur into graphene-backboned mesoporous carbon with a PPy nanocoating. They exhibit a high reversible capacity for as long as 400 cycles with an ultra slow decay rate of 0.05% per cycle at the high rate of 1-3 C due to the efficient immobilization of polysulfides.Sandwich-type, two-dimensional hybrid nanosheets were fabricated by the infiltration of nanosized sulfur into graphene-backboned mesoporous carbon with a PPy nanocoating. They exhibit a high reversible capacity for as long as 400 cycles with an ultra slow decay rate of 0.05% per cycle at the high rate of 1-3 C due to the efficient immobilization of polysulfides. Electronic supplementary information (ESI) available: Experimental details, BET, SEM, XPS and more electrochemical data. See DOI: 10.1039/c5nr01015b

  19. Enhanced electrorheological activity of polyaniline coated mesoporous silica with high aspect ratio.

    PubMed

    Noh, Jungchul; Yoon, Chang-Min; Jang, Jyongsik

    2016-05-15

    Polyaniline-coated mesoporous silica (PANI/mSiO2) materials with different aspect ratios (L/D=1, 5, and 10) were fabricated by a vapor deposition polymerization (VDP) method to investigate the geometric effect on electrorheological (ER) activity. The PANI/mSiO2 materials were dedoped by a facile NH4OH treatment to reduce the conductivity to a level appropriate for ER applications. Notably, the PANI/mSiO2-based ER fluids exhibited enhanced ER performance with increasing aspect ratio. In particular, the PANI/mSiO2 material with the highest aspect ratio manifested the highest ER activity, which was attributed to geometric effects on flow resistance and mechanical stability. Moreover, the ER materials with higher aspect ratios showed improved dielectric properties of large achievable polarizability and short relaxation time. Hence, the synergistic contribution of geometric effects and dielectric properties resulted in enhanced ER activity. Consequently, this study provides insight into an effective method to improve ER performance by simple manipulation of the particle geometry. PMID:26950396

  20. One-pot template-free preparation of mesoporous TiO{sub 2} hollow spheres and their photocatalytic activity

    SciTech Connect

    Kang, Shizhao; Yin, Dieer; Li, Xiangqing; Li, Liang; Mu, Jin

    2012-11-15

    Highlights: ► Mesoporous TiO{sub 2} hollow spheres were prepared in a one-pot process. ► The process does not involve any templates and surfactants. ► The TiO{sub 2} hollow spheres display high photocatalytic activity. -- Abstract: Mesoporous TiO{sub 2} hollow spheres were prepared in a solvothermal process, which did not involve any templates and surfactants. Meanwhile, the photocatalytic activity of TiO{sub 2} hollow spheres was studied using methyl orange as a probe. The results indicate that the anatase TiO{sub 2} hollow spheres with mesoporous walls and high specific surface area (141 m{sup 2} g{sup −1}) can be obtained using this simple method. The mean diameter and wall thickness of spheres are about 700 nm and 90 nm, respectively. Moreover, the as-prepared TiO{sub 2} hollow spheres display high photocatalytic activity with 98% of degradation ratio of methyl orange after 30 min irradiation.

  1. Nanogold/mesoporous carbon foam-mediated silver enhancement for graphene-enhanced electrochemical immunosensing of carcinoembryonic antigen.

    PubMed

    Lin, Dajie; Wu, Jie; Ju, Huangxian; Yan, Feng

    2014-02-15

    Nanogold functionalized mesoporous carbon foam (Au/MCF) coupling with a signal amplification by C-Au synergistic silver enhancement was designed for sensitive electrochemical immunosensing of biomarker. The Au/MCF was prepared by in situ growth of nanogold on carboxylated MCF and used as a tracing tag to label signal antibody via the inherent interaction between protein and nanogold. The immunosensor was prepared by covalently immobilizing capture antibody on an electrochemically reduced graphene oxide/chitosan film modified glassy carbon electrode. Through a sandwich-type immunoreaction, Au/MCF tags were captured on the immunoconjugates to induce a silver deposition process. The electrochemical stripping signal of the deposited silver was used to monitor the immunoreaction. The Au/MCF-mediated silver enhancement along with the graphene-promoted electron transfer led to high detection sensitivity of carcinoembryonic antigen. Under optimal conditions, the proposed immunoassay method showed wide linear range from 0.05 pg mL(-1) to 1 ng mL(-1) and a detection limit down to 0.024 pg mL(-1). The newly designed amplification strategy holds great potential for ultrasensitive electrochemical biosensing of other analytes. PMID:24041661

  2. Physicochemical and porosity characteristics of thermally regenerated activated carbon polluted with biological activated carbon process.

    PubMed

    Dong, Lihua; Liu, Wenjun; Jiang, Renfu; Wang, Zhansheng

    2014-11-01

    The characteristics of thermally regenerated activated carbon (AC) polluted with biological activated carbon (BAC) process were investigated. The results showed that the true micropore and sub-micropore volume, pH value, bulk density, and hardness of regenerated AC decreased compared to the virgin AC, but the total pore volume increased. XPS analysis displayed that the ash contents of Al, Si, and Ca in the regenerated AC respectively increased by 3.83%, 2.62% and 1.8%. FTIR spectrum showed that the surface functional groups of virgin and regenerated AC did not change significantly. Pore size distributions indicated that the AC regeneration process resulted in the decrease of micropore and macropore (D>10 μm) volume and the increase of mesopore and macropore (0.1 μm

  3. Simple fabrication of N-doped mesoporous TiO2 nanorods with the enhanced visible light photocatalytic activity

    PubMed Central

    2014-01-01

    N-doped mesoporous TiO2 nanorods were fabricated by a modified and facile sol–gel approach without any templates. Ammonium nitrate was used as a raw source of N dopants, which could produce a lot of gasses such as N2, NO2, and H2O in the process of heating samples. These gasses were proved to be vitally important to form the special mesoporous structure. The samples were characterized by the powder X-ray diffraction, X-ray photoelectron spectrometer, nitrogen adsorption isotherms, scanning electron microscopy, transmission electron microscopy, and UV-visible absorption spectra. The average length and the cross section diameter of the as-prepared samples were ca. 1.5 μm and ca. 80 nm, respectively. The photocatalytic activity was evaluated by photodegradation of methylene blue (MB) in aqueous solution. The N-doped mesoporous TiO2 nanorods showed an excellent photocatalytic activity, which may be attributed to the enlarged surface area (106.4 m2 g-1) and the narrowed band gap (2.05 eV). Besides, the rod-like photocatalyst was found to be easy to recycle. PMID:24428848

  4. Activators generated by electron transfer for atom transfer radical polymerization of styrene in the presence of mesoporous silica nanoparticles

    SciTech Connect

    Khezri, Khezrollah; Roghani-Mamaqani, Hossein

    2014-11-15

    Graphical abstract: Effect of mesoporous silica nanoparticles (MCM-41) on the activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP) is investigated. Decrement of conversion and number average molecular weight and also increment of polydispersity index (PDI) values are three main results of addition of MCM-41 nanoparticles. Incorporation of MCM-41 nanoparticles in the polystyrene matrix can clearly increase thermal stability and decrease glass transition temperature of the nanocomposites. - Highlights: • Spherical morphology, hexagonal structure, and high surface area with regular pore diameters of the synthesized MCM-41 nanoparticles are examined. • AGET ATRP of styrene in the presence of MCM-41 nanoparticles is performed. • Effect of MCM-41 nanoparticles addition on the polymerization rate, conversion and molecular weights of the products are discussed. • Improvement in thermal stability of the nanocomposites and decreasing T{sub g} values was also observed by incorporation of MCM-41 nanoparticles. - Abstract: Activator generated by electron transfer for atom transfer radical polymerization was employed to synthesize well-defined mesoporous silica nanoparticles/polystyrene composites. Inherent features of spherical mesoporous silica nanoparticles were evaluated by nitrogen adsorption/desorption isotherm, X-ray diffraction and scanning electron microscopy analysis techniques. Conversion and molecular weight evaluations were carried out using gas and size exclusion chromatography respectively. By the addition of only 3 wt% mesoporous silica nanoparticles, conversion decreases from 81 to 58%. Similarly, number average molecular weight decreases from 17,116 to 12,798 g mol{sup −1}. However, polydispersity index (PDI) values increases from 1.24 to 1.58. A peak around 4.1–4.2 ppm at proton nuclear magnetic resonance spectroscopy results clearly confirms the living nature of the polymerization. Thermogravimetric analysis shows that thermal stability of the nanocomposites increases by adding nanoparticles content. Decrease of glass transition temperature is also demonstrated by the addition of 3 wt% of silica nanoparticles according to the differential scanning calorimetry results.

  5. Electrochemical determination of toxic ractopamine at an ordered mesoporous carbon modified electrode.

    PubMed

    Yang, Xiao; Feng, Bo; Yang, Peng; Ding, Yonglan; Chen, Yi; Fei, Junjie

    2014-02-15

    A sensitive electrochemical sensor was developed to detect toxic ractopamine using ordered mesoporus carbon (OMC) modified glass carbon electrode (OMC/GCE). Cyclic voltammetry was used to investigate the electrochemical behaviours of ractopamine on OMC/GCE. The results indicated that the OMC modified electrode can remarkably enhance electrocatalytic activity towards the oxidation of ractopamine with a great increase of peak current. The oxidation mechanism was studied and the results showed that the oxidation of ractopamine involved two protons and two electrons of its two phenolic hydroxyl groups. The signal for the determination of ractopamine was recorded using differential pulse voltammetry (DPV) and the optimisation for the experimental conditions was also conducted. The results showed that the response of the sensor to concentration of ractopamine displayed a linear correlation over a range from 0.085 ?M to 8.0 ?M with a detection limit of 0.06 ?M, demonstrating favourable sensitivity and selectivity for the detection of ractopamine. Finally, the method was successfully applied for the determination of ractopamine in pork samples with satisfying recoveries in the range of 96.6-104.5% and excellent RSD of less than 5%. PMID:24128523

  6. Real-time monitoring of enzyme activity in a mesoporous silicon double layer

    NASA Astrophysics Data System (ADS)

    Orosco, Manuel M.; Pacholski, Claudia; Sailor, Michael J.

    2009-04-01

    The activity of certain proteolytic enzymes is often an indicator of disease states such as cancer, stroke and neurodegeneracy, so there is a need for rapid assays that can characterize the kinetics and substrate specificity of enzymatic reactions. Nanostructured membranes can efficiently separate biomolecules, but coupling a sensitive detection method to such a membrane remains difficult. Here, we demonstrate a single mesoporous nanoreactor that can isolate and quantify in real time the reaction products of proteases. The reactor consists of two layers of porous films electrochemically prepared from crystalline silicon. The upper layer, with large pore sizes (~100 nm in diameter), traps the protease and acts as the reactor. The lower layer, with smaller pore sizes (~6 nm), excludes the proteases and other large proteins and captures the reaction products. Infiltration of the digested fragments into the lower layer produces a measurable change in optical reflectivity, and this allows label-free quantification of enzyme kinetics in real time within a volume of ~5 nl.

  7. Controlled synthesis and structure tunability of photocatalytically active mesoporous metal-based stannate nanostructures

    NASA Astrophysics Data System (ADS)

    Liu, Caihong; Chen, Haiyan; Ren, Zheng; Dardona, Sameh; Piech, Martin; Gao, Haiyong; Gao, Pu-Xian

    2014-03-01

    A variety of stannate nanostructures have been fabricated for UV photocatalysis, including zinc- and cadmium-based stannates. As the template nanostructures, high surface-area mesoporous metal hydroxystannate [ZnSn(OH)6 and CdSn(OH)6] nanoparticles (>100 m2/g) have been synthesized using a simple, low-temperature substitution chemical process with controlled porosity, morphology and crystallinity. Post-synthetic thermal treatments were employed to obtain amorphous ZnSnO3, CdSnO3, ilmenite CdSnO3, and crystalline Zn2SnO4-SnO2 nanoparticles. As a result, the band gaps can be tuned from 5.4 eV to 3.3 eV and from 4.9 eV to 2.1 eV for Zn-based and Cd-based stannates, respectively. Amorphous ZnSnO3 porous nanoparticles showed highest activity toward dye degradation under UV illumination followed by the Zn2SnO4-SnO2 and ilmenite CdSnO3 nanostructures due to their beneficial band structure alignment, high conductivities, and high specific surface areas. This study may provide an important strategy for high throughput synthesis and screening of functional complex metal oxide nanomaterials, while the enabled stannate nanomaterials could be utilized in various applications.

  8. Comparison of the surface features of two wood-based activated carbons

    SciTech Connect

    Salame, I.I.; Bandosz, T.J.

    2000-02-01

    The surface features of two carbons of wood origin were compared. One sample was manufactured using phosphoric acid activation and the other using potassium hydroxide activation. To check the susceptibility to oxidation and the stability of the porous structure, the samples were oxidized with ammonium persulfate. Structural properties of carbons and their oxidized counterparts were determined using sorption of nitrogen. Surface acidity was evaluated using Boehm titration, potentiometric titration, inverse gas chromatography, and diffuse reflectance FTIR. It was demonstrated that, despite the same wood origin, the carbons significantly differ in their pore structure and surface chemistry. The carbon obtained using KOH activation is homogeneously microporous with high surface area around 2,300 m{sup 2}/g (BET). On the other hand, the carbon manufactured using phosphoric acid contains a high volume of mesopores and its surface area is significantly lower. The carbons also differ in their surface chemistry and susceptibility to oxidation.

  9. Probing Mechanisms for Enzymatic Activity Enhancement of Organophosphorus Hydrolase in Functionalized Mesoporous Silica

    SciTech Connect

    Chen, Baowei; Lei, Chenghong; Shin, Yongsoon; Liu, Jun

    2009-12-25

    We have previously reported that organophosphorus hydrolase (OPH) can be spontaneously entrapped in functionalized mesoporous silica (FMS) with HOOC - as the functional groups and the entrapped OPH in HOOC-FMS showed enhanced enzyme specific activity. This work is to study the mechanisms that why OPH entrapped in FMS displayed the enhanced activity in views of OPH-FMS interactions using spectroscopic methods. The circular dichroism (CD) spectra show that, comparing to the secondary structure of OPH free in solution, OPH in HOOC-FMS displayed increased a-helix/b-strand transition of OPH with increased OPH loading density. The fluorescence emission spectra of Trp residues were used to assess the tertiary structural changes of the enzyme. There was a 42% increase in fluorescence. This is in agreement with the fact that the fluorescence intensity of OPH was increased accompanying with the increased OPH activity when decreasing urea concentrations in solution. The steady-state anisotropy was increased after OPH entrapping in HOOC-FMS comparing to the free OPH in solution, indicating that protein mobility was reduced upon entrapment. The solvent accessibility of Trp residues of OPH was probed by using acrylamide as a collisional quencher. Trp residues of OPH-FMS had less solvent exposure comparing with free OPH in solution due to its electrostatical binding to HOOC-FMS thereby displaying the increased fluorescence intensity. These results suggest the interactions of OPH with HOOC-FMS resulted in the protein immobilization and a favorable conformational change for OPH in the crowded confinement space and accordingly the enhanced activity.

  10. Novel Ordered Mesoporous Carbon Based Sulfonic Acid as an Efficient Catalyst in the Selective Dehydration of Fructose into 5-HMF: the Role of Solvent and Surface Chemistry.

    PubMed

    Karimi, Babak; Mirzaei, Hamid M; Behzadnia, Hesam; Vali, Hojatollah

    2015-09-01

    Novel ionic liquid derived ordered mesoporous carbons functionalized with sulfonic acid groups IOMC-ArSO3H and GIOMC-ArSO3H were prepared, characterized, and examined in the dehydration reaction of fructose into 5-hydroxymethylfurfural (5-HMF) both in aqueous and nonaqueous systems. To study and correlate the surface properties of these carbocatalysts and some other SBA-15 typed solid acids with 5-HMF yield, hydrophilicity index (H-index) were employed in the fructose dehydration. Our study systematically declared that almost a criterion may be expected for application of solid acids in which by increasing H-index value up to 0.8 the HMF yield enhances accordingly. More increase in H-index up to 1.3 did not change the HMF yield profoundly. Although, it has been shown that the catalyst with larger H-index (∼1.3) resulted in higher activity both in aqueous and 2-propanol systems, during the recycling process deactivation occurs because of more water uptake and the catalysts with optimum amount of H-index (∼0.8) is more robust in the dehydration of fructose. PMID:26259108

  11. Characterization of the micropore structure of activated carbons by adsorptions of nitrogen and some hydrocarbons

    SciTech Connect

    Guezel, F.

    1999-02-01

    In the present study the effects of the duration of carbonization and physical activation properties of activated carbon from vegetable materials were investigated. Peanut shells were used to obtain active carbon. These shells were activated chemically with ZnCl{sub 2} and/or CO{sub 2} for different times, and the micropore structures of these active carbons were studied by measuring the adsorption isotherms for nitrogen and some hydrocarbons such as benzene, n-butane, isobutane, 2,2-dimethylbutane, and isooctane. As the physical activation time was increased, the primary micropores, which were measured at 0.01 relative pressure, were reduced, and they were replaced by larger secondary and tertiary micropores which were measured at 0.15--0.01 and 0.30--0.15 relative pressures. The ratios of the mesopore volume to the micropore volume also increased as the duration of physical activation increased.

  12. Activated carbons obtained from sewage sludge by chemical activation: gas-phase environmental applications.

    PubMed

    Boualem, T; Debab, A; Martínez de Yuso, A; Izquierdo, M T

    2014-07-01

    The objective of this study was to evaluate the adsorption capacity for toluene and SO2 of low cost activated carbons prepared from sewage sludge by chemical activation at different impregnation ratios. Samples were characterized by proximate and ultimate analyses, thermogravimetry, infrared spectroscopy and N2 adsorption. Because of the low carbon content of the raw material, the development of porosity in the activated carbons was mainly of a mesoporous nature, with surface areas lower than 300 m(2)/g. The study of gas-phase applications for activated carbons from sewage sludge was carried out using both an organic and an inorganic compound in order to screen for possible applications. Toluene adsorption capacity at saturation was around 280 mg/g, which is a good level of performance given the high ash content of the activated carbons. However, dynamic experiments at low toluene concentration presented diffusion problems resulting from low porosity development. SO2 adsorption capacity is associated with average micropore size, which can be controlled by the impregnation ratio used to prepare the activated carbons. PMID:24747937

  13. Preparation of activated carbons from macadamia nut shell and coconut shell by air activation

    SciTech Connect

    Tam, M.S.; Antal, M.J. Jr.

    1999-11-01

    A novel, three-step process for the production of high-quality activated carbons from macadamia nut shell and coconut shell charcoals is described. In this process the charcoal is (1) heated to a high temperature (carbonized), (2) oxidized in air following a stepwise heating program from low (ca. 450 K) to high (ca. 660 K) temperatures (oxygenated), and (3) heated again in an inert environment to a high temperature (activated). By use of this procedure, activated carbons with surface areas greater than 1,000 m{sub 2}/g are manufactured with an overall yield of 15% (based on the dry shell feed). Removal of carbon mass by the development of mesopores and macropores is largely responsible for increases in the surface area of the carbons above 600 m{sub 2}/g. Thus, the surface area per gram of activated carbon can be represented by an inverse function of the yield for burnoffs between 15 and 60%. These findings are supported by mass-transfer calculations and pore-size distribution measurements. A kinetic model for gasification of carbon by oxygen, which provides for an Eley-Rideal type reaction of a surface oxide with oxygen in air, fits the measured gasification rates reasonably well over the temperature range of 550--660 K.

  14. Specific aptamer-conjugated mesoporous silica-carbon nanoparticles for HER2-targeted chemo-photothermal combined therapy.

    PubMed

    Wang, Kaiyuan; Yao, Hui; Meng, Ying; Wang, Yi; Yan, Xueying; Huang, Rongqin

    2015-04-01

    Tumor-specific therapeutic platforms designed for combined tumor therapy has recently received wide attention. In this work, a new HB5 aptamer-functionalized mesoporous silica-carbon based doxorubicin (DOX)-loaded system (MSCN-PEG-HB5/DOX) was successfully constructed and characterized for chemo-photothermal combined therapy of human epithelial growth factor receptor 2 (HER2)-positive breast cancer cells. The in vitro release result showed that MSCN-PEG-HB5/DOX exhibited pH-sensitive and NIR-triggered release manner. HB5-modified nanoparticles showed significant higher cellular uptake in HER2-positive breast cancer cells (SK-BR-3) but not in normal breast epithelial cells (MCF-10A), compared to unmodified counterparts. The intracellular uptake of functional nanoparticles was mainly based on the receptor-mediated mechanism which was energy-dependent. Cytotoxicity experiments demonstrated that combined therapy induced highest cell killing effect compared to chemotherapy and photothermal therapy alone. The combination index (CI) was 0.253 indicating the synergistic effect of chemotherapy and photothermal therapy. These findings suggested that MSCN-PEG-HB5/DOX was a potential chemo-photothermal therapeutic platform targeting to HER2-positive breast cancers. PMID:25596325

  15. The electrochemical reactions of SnO2 with Li and Na: a study using thin films and mesoporous carbons

    DOE PAGESBeta

    Mahurin, Shannon Mark; Mayes, Richard T; Dai, Sheng; Veith, Gabriel M

    2015-01-01

    In this work we have determined the room temperature electrochemical reactivity of SnO2 thin films and mesoporous carbons filled with SnO2 anodes with Na, and compare the results with those obtained during the reaction with Li. We show that SnO2 can reversibly deliver up to 6.2 Li/SnO2 whereas the reaction with Na is significantly limited. The initial discharge capacity is equivalent to less than 4 Na/SnO2, which is expected to correspond to the formation of 2 Na2O and Sn. This limited discharge capacity suggests the negative role of the formed Na2O matrix upon the reversible reaction of Sn clusters. Moreover,more » the reversible cycling of less than 1 Na/SnO2, despite the utilization of 6-7 nm SnO2 particles, is indicative of sluggish reaction kinetics. The origin of this significant capacity reduction is likely due to the formation of a diffusion limiting interface. Furthermore, there is a larger apparent hysteresis compared to Li. These results point to the need to design composite structures of SnO2 nanoparticles with suitable morphological and conductivity components.« less

  16. Synthesis of graphitic ordered mesoporous carbon with cubic symmetry and its application in lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Kim, Min-Seop; Jeong, Jinhoo; Cho, Won Il; Kim, Woong

    2016-03-01

    The lithium-sulfur (Li-S) battery faces a couple of major problems in practical applications, including the low conductivity of sulfur and the dissolution of polysulfides. A cathode constructed using a composite of sulfur and ordered mesoporous carbon (OMC) is a promising solution to both problems, as OMCs can have high conductivity and a complex pore structure to trap polysulfides. In this work, we demonstrate that performance of the Li-S battery can be significantly enhanced by using an OMC with a high degree of graphitization and a pore network with cubic symmetry. This graphitic OMC (GOMC) can be produced in a single step using iron phthalocyanine precursor and a silica template with cubic Ia3d symmetry. The GOMC-sulfur (GOMC/S) composite is 175% higher in electrical conductivity compared to the typical OMC-sulfur (OMC/S) composite. In addition, the three-dimensional pore network in GOMC prevents the migration of dissolved polysulfides. These characteristics of GOMC contribute to the improved rate capability and cyclability of the corresponding Li-S battery.

  17. The electrochemical reactions of SnO2 with Li and Na: a study using thin films and mesoporous carbons

    SciTech Connect

    Mahurin, Shannon Mark; Mayes, Richard T; Dai, Sheng; Veith, Gabriel M

    2015-01-01

    In this work we have determined the room temperature electrochemical reactivity of SnO2 thin films and mesoporous carbons filled with SnO2 anodes with Na, and compare the results with those obtained during the reaction with Li. We show that SnO2 can reversibly deliver up to 6.2 Li/SnO2 whereas the reaction with Na is significantly limited. The initial discharge capacity is equivalent to less than 4 Na/SnO2, which is expected to correspond to the formation of 2 Na2O and Sn. This limited discharge capacity suggests the negative role of the formed Na2O matrix upon the reversible reaction of Sn clusters. Moreover, the reversible cycling of less than 1 Na/SnO2, despite the utilization of 6-7 nm SnO2 particles, is indicative of sluggish reaction kinetics. The origin of this significant capacity reduction is likely due to the formation of a diffusion limiting interface. Furthermore, there is a larger apparent hysteresis compared to Li. These results point to the need to design composite structures of SnO2 nanoparticles with suitable morphological and conductivity components.

  18. Synthesis of graphitic ordered mesoporous carbon with cubic symmetry and its application in lithium-sulfur batteries.

    PubMed

    Kim, Min-Seop; Jeong, Jinhoo; Il Cho, Won; Kim, Woong

    2016-03-29

    The lithium-sulfur (Li-S) battery faces a couple of major problems in practical applications, including the low conductivity of sulfur and the dissolution of polysulfides. A cathode constructed using a composite of sulfur and ordered mesoporous carbon (OMC) is a promising solution to both problems, as OMCs can have high conductivity and a complex pore structure to trap polysulfides. In this work, we demonstrate that performance of the Li-S battery can be significantly enhanced by using an OMC with a high degree of graphitization and a pore network with cubic symmetry. This graphitic OMC (GOMC) can be produced in a single step using iron phthalocyanine precursor and a silica template with cubic Ia3d symmetry. The GOMC-sulfur (GOMC/S) composite is 175% higher in electrical conductivity compared to the typical OMC-sulfur (OMC/S) composite. In addition, the three-dimensional pore network in GOMC prevents the migration of dissolved polysulfides. These characteristics of GOMC contribute to the improved rate capability and cyclability of the corresponding Li-S battery. PMID:26890309

  19. Separating proteins with activated carbon.

    PubMed

    Stone, Matthew T; Kozlov, Mikhail

    2014-07-15

    Activated carbon is applied to separate proteins based on differences in their size and effective charge. Three guidelines are suggested for the efficient separation of proteins with activated carbon. (1) Activated carbon can be used to efficiently remove smaller proteinaceous impurities from larger proteins. (2) Smaller proteinaceous impurities are most efficiently removed at a solution pH close to the impurity's isoelectric point, where they have a minimal effective charge. (3) The most efficient recovery of a small protein from activated carbon occurs at a solution pH further away from the protein's isoelectric point, where it is strongly charged. Studies measuring the binding capacities of individual polymers and proteins were used to develop these three guidelines, and they were then applied to the separation of several different protein mixtures. The ability of activated carbon to separate proteins was demonstrated to be broadly applicable with three different types of activated carbon by both static treatment and by flowing through a packed column of activated carbon. PMID:24898563

  20. Iron phthalocyanine modified mesoporous titania nanoparticles for photocatalytic activity and CO2 capture applications.

    PubMed

    Ramacharyulu, P V R K; Muhammad, Raeesh; Praveen Kumar, J; Prasad, G K; Mohanty, Paritosh

    2015-10-21

    An iron(II)phthalocyanine (Fepc) modified mesoporous titania (Fepc-TiO2) nanocatalyst with a specific surface area of 215 m(2) g(-1) has been synthesized by a hydrothermal method. Fepc-TiO2 degrades one of the highly toxic chemical warfare agents, sulfur mustard (SM), photocatalytically under sunlight with an exposure time of as low as 70 min. Furthermore, the mesoporous Fepc-TiO2 also captured 2.1 mmol g(-1) of CO2 at 273 K and 1 atm. PMID:26393761

  1. Enhanced photocatalytic activity of bimodal mesoporous titania powders by C60 modification.

    PubMed

    Yu, Jiaguo; Ma, Tingting; Liu, Gang; Cheng, Bei

    2011-07-01

    In this work, fullerene modified TiO(2) nanocomposites (denoted as C(60)/TiO(2)) with low C(60) loadings (0-1.5 wt.%) have been prepared by a simple hydrothermal method using tetrabutylorthotitanate (TBOT, Ti(OC(4)H(9))(4)) as the titanium precursor. The as-prepared C(60)/TiO(2) nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, UV-visible spectrophotometry, nitrogen adsorption, and X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy. The formation of hydroxyl radicals (˙OH) on the surface of UV-illuminated TiO(2) is probed by photoluminescence using terephthalic acid as a probe molecule. Our results have demonstrated that C(60) molecules can be dispersed as a monolayer onto bimodal mesoporous TiO(2)via covalent bonding. The photocatalytic oxidation rate of gas-phase acetone over C(60)/TiO(2) nanocomposites is greater than that over pure TiO(2), commercial Degussa P25 (P25) and C(60)-TiO(2) counterparts prepared by simple impregnating mixing. In particular, 0.5 wt.% C(60)/TiO(2) nanocomposites show the greatest photocatalytic activity with the rate constant k exceeding that of P25 by a factor of 3.3. Based on the results of the current study, we propose that C(60) molecules doped onto TiO(2) act as "electron acceptors" responsible for the efficient separation of photogenerated charge carriers and the enhancement of photocatalytic activity. The proposed mechanism for the observed photocatalytic performance of C(60)/TiO(2) nanocomposites is further corroborated by experiments on hydroxyl radical and transient photocurrent response. PMID:21552575

  2. A novel carbon fiber based porous carbon monolith

    SciTech Connect

    Burchell, T.D.; Klett, J.W.; Weaver, C.E.

    1995-07-01

    A novel porous carbon material based on carbon fibers has been developed. The material, when activated, develops a significant micro- or mesopore volume dependent upon the carbon fiber type utilized (isotropic pitch or polyacrylonitrile). The materials will find applications in the field of fluid separations or as a catalyst support. Here, the manufacture and characterization of our porous carbon monoliths are described.

  3. Preparation of Bamboo Chars and Bamboo Activated Carbons to Remove Color and COD from Ink Wastewater.

    PubMed

    Hata, Motohide; Amano, Yoshimasa; Thiravetyan, Paitip; Machida, Motoi

    2016-01-01

    Bamboo chars and bamboo activated carbons prepared by steam activation were applied for ink wastewater treatment. Bamboo char at 800 °C was the best for the removal of color and chemical oxygen demand (COD) from ink wastewater compared to bamboo chars at 300 to 700 °C due to higher surface area and mesopore volume. Bamboo activated carbon at 600 °C (S600) was the best compared to bamboo activated carbon at 800 °C (S800), although S800 had larger surface area (1108 m(2)/g) than S600 (734 m(2)/g). S600 had higher mesopore volume (0.20 cm(3)/g) than S800 (0.16 cm(3)/g) and therefore achieved higher color and COD removal. All bamboo activated carbons showed higher color and COD removal efficiency than commercial activated carbon. In addition, S600 had the superior adsorption capacity for methylene blue (0.89 mmol/g). Therefore, bamboo is a suitable material to prepare adsorbents for removal of organic pollutants. PMID:26803031

  4. Bimodal activated carbons derived from resorcinol-formaldehyde cryogels

    NASA Astrophysics Data System (ADS)

    Szczurek, Andrzej; Amaral-Labat, Gisele; Fierro, Vanessa; Pizzi, Antonio; Celzard, Alain

    2011-06-01

    Resorcinol-formaldehyde cryogels prepared at different dilution ratios have been activated with phosphoric acid at 450 °C and compared with their carbonaceous counterparts obtained by pyrolysis at 900 °C. Whereas the latter were, as expected, highly mesoporous carbons, the former cryogels had very different pore textures. Highly diluted cryogels allowed preparation of microporous materials with high surface areas, but activation of initially dense cryogels led to almost non-porous carbons, with much lower surface areas than those obtained by pyrolysis. The optimal acid concentration for activation, corresponding to stoichiometry between molecules of acid and hydroxyl groups, was 2 M l-1, and the acid-cryogel contact time also had an optimal value. Such optimization allowed us to achieve surface areas and micropore volumes among the highest ever obtained by activation with H3PO4, close to 2200 m2 g-1 and 0.7 cm3 g-1, respectively. Activation of diluted cryogels with a lower acid concentration of 1.2 M l-1 led to authentic bimodal activated carbons, having a surface area as high as 1780 m2 g-1 and 0.6 cm3 g-1 of microporous volume easily accessible through a widely developed macroporosity.

  5. Adsorption of SO2 and NO from incineration flue gas onto activated carbon fibers.

    PubMed

    Liu, Zhen-Shu

    2008-11-01

    Activated carbon fibers (ACFs) were used to remove SO2 and NO from incineration flue gas. Three types of ACFs in their origin state and after pretreatment with HNO3, NaOH, and KOH were investigated. The removal efficiencies of SO2 and NO were determined experimentally at defined SO2 and NO concentrations and at temperatures of 150, 200 and 260 degrees C. Experimental results indicated that the removal efficiencies of SO2 and NO using the original ACFs were < 56% and < 27%, respectively. All ACFs modified with HNO3, NaOH, and KOH solution could increase the removal efficiencies of SO(2) and NO. The mesopore volumes and functional groups of ACFs are important in determining the removal of SO2 and NO. When the mesopore volumes of the ACFs are insufficient for removing SO2 and NO, the functional groups on the ACFs are not important in determining the removal of SO2 and NO. On the contrary, the effects of the functional groups on the removal of SO2 and NO are more important than the mesopore volumes as the amount of mesopores on the ACFs is sufficient to remove SO2 and NO. Moreover, the removal efficiencies of SO2 and NO were greatest at 200 degrees C. When the inlet concentration of SO2 increased to 600 ppm, the removal efficiency of SO2 increased slightly and the removal efficiency of NO decreased. PMID:18083361

  6. A sensitive amperometric sensor for hydrazine and hydrogen peroxide based on palladium nanoparticles/onion-like mesoporous carbon vesicle.

    PubMed

    Bo, Xiangjie; Bai, Jing; Ju, Jian; Guo, Liping

    2010-08-18

    Onion-like mesoporous carbon vesicle (MCV) with multilayer lamellar structure was synthesized by a simply aqueous emulsion co-assembly approach. Palladium (Pd) nanoparticles were deposited on the MCV matrix (Pd/MCV) by chemical reduction of H(2)PdCl(4) with NaBH(4) in aqueous media. Pd(X)/MCV (X wt.% indicates the Pd loading amount) nanocomposites with different Pd loading amount were obtained by adjusting the ratio of precursors. The particular structure of the MCV results in efficient mass transport and the onion-like layers of MCV allows for the obtainment of highly dispersed Pd nanoparticles. The introduction of Pd nanoparticles on the MCV matrix facilitates hydrazine oxidation at more negative potential and delivers higher oxidation current in comparison with MCV. A linear range from 2.0 x 10(-8) to 7.1 x 10(-5) M and a low detection limit of 14.9 nM for hydrazine are obtained at Pd(25)/MCV nanocomposite modified glassy carbon (GC) electrode. A nonenzymatic amperometric sensor for hydrogen peroxide based on the Pd(25)/MCV nanocomposite modified GC electrode is also developed. Compared with MCV modified GC electrode, the Pd(25)/MCV nanocomposite modified GC electrode displays enhanced amperometric responses towards hydrogen peroxide and gives a linear range from 1.0 x 10(-7) to 6.1 x 10(-3) M. The Pd(25)/MCV nanocomposite modified GC electrode achieves 95% of the steady-current for hydrogen peroxide within 1s. The combination of the unique properties of Pd nanoparticles and the porous mesostructure of MCV matrix guarantees the improved analytical performance for hydrazine and hydrogen peroxide. PMID:20708112

  7. Application of low-voltage field-emission SEM to the study of internal pore structures of activated carbon

    SciTech Connect

    Liu, J.; Ornberg, R.L.

    1996-12-31

    Activated carbon has interesting and useful properties for industrial applications. It has been used extensively in purification, separation, chemical recovery and catalysis. To achieve a predictable performance of activated carbon materials, it is necessary to develop a comprehensive understanding of the pore structure including pore size, pore shape, and pore surface chemistry. Macropores (> 50 nm), mesopores (2-50 nm) and micropores (< 2 nm) generally coexist in activated carbon. It is thus desirable to synthesize activated carbon with controlled pore structures to optimize its performance. We previously reported the characterization of the surface pore structure of activated carbon by field emission SEM (FESEM) and the examination of the internal pore structure by HAADF/HRTEM techniques. However, both HAADF and HRTEM techniques give only limited information about the carbon pore structure. We report here some preliminary observation of the internal pore structure of activated carbon by high resolution low voltage FESEM technique.

  8. Breakthrough CO₂ adsorption in bio-based activated carbons.

    PubMed

    Shahkarami, Sepideh; Azargohar, Ramin; Dalai, Ajay K; Soltan, Jafar

    2015-08-01

    In this work, the effects of different methods of activation on CO2 adsorption performance of activated carbon were studied. Activated carbons were prepared from biochar, obtained from fast pyrolysis of white wood, using three different activation methods of steam activation, CO2 activation and Potassium hydroxide (KOH) activation. CO2 adsorption behavior of the produced activated carbons was studied in a fixed-bed reactor set-up at atmospheric pressure, temperature range of 25-65°C and inlet CO2 concentration range of 10-30 mol% in He to determine the effects of the surface area, porosity and surface chemistry on adsorption capacity of the samples. Characterization of the micropore and mesopore texture was carried out using N2 and CO2 adsorption at 77 and 273 K, respectively. Central composite design was used to evaluate the combined effects of temperature and concentration of CO2 on the adsorption behavior of the adsorbents. The KOH activated carbon with a total micropore volume of 0.62 cm(3)/g and surface area of 1400 m(2)/g had the highest CO2 adsorption capacity of 1.8 mol/kg due to its microporous structure and high surface area under the optimized experimental conditions of 30 mol% CO2 and 25°C. The performance of the adsorbents in multi-cyclic adsorption process was also assessed and the adsorption capacity of KOH and CO2 activated carbons remained remarkably stable after 50 cycles with low temperature (160°C) regeneration. PMID:26257348

  9. Multiscale anode materials in lithium ion batteries by combining micro- with nanoparticles: design of mesoporous TiO2 microfibers@nitrogen doped carbon composites

    NASA Astrophysics Data System (ADS)

    Cheng, Wei; Rechberger, Felix; Primc, Darinka; Niederberger, Markus

    2015-08-01

    TiO2 has been considered as a promising anode material for lithium ion batteries. However, its poor rate capability originating from the intrinsically low lithium ion diffusivity and its poor electronic conductivity hampers putting such an application into practice. Both issues can be addressed by nanostructure engineering and conductive surface coating. Herein, we report a template-assisted synthesis of micron sized TiO2 fibers consisting of a mesoporous network of anatase nanoparticles of about 7.5 nm and coated by N doped carbon. In a first step, an amorphous layer of TiO2 was deposited on cobalt silicate nanobelts and subsequently transformed into crystalline anatase nanoparticles by hydrothermal treatment. The N doped carbon coating was realized by in situ polymerization of dopamine on the crystalline TiO2 followed by annealing under N2. After removal of the template, we obtained the final mesoporous TiO2 fibers@N doped carbon composite. Electrochemical tests revealed that the composite electrode exhibited excellent electrochemical properties in terms of specific capacity, rate performance and long term stability.TiO2 has been considered as a promising anode material for lithium ion batteries. However, its poor rate capability originating from the intrinsically low lithium ion diffusivity and its poor electronic conductivity hampers putting such an application into practice. Both issues can be addressed by nanostructure engineering and conductive surface coating. Herein, we report a template-assisted synthesis of micron sized TiO2 fibers consisting of a mesoporous network of anatase nanoparticles of about 7.5 nm and coated by N doped carbon. In a first step, an amorphous layer of TiO2 was deposited on cobalt silicate nanobelts and subsequently transformed into crystalline anatase nanoparticles by hydrothermal treatment. The N doped carbon coating was realized by in situ polymerization of dopamine on the crystalline TiO2 followed by annealing under N2. After removal of the template, we obtained the final mesoporous TiO2 fibers@N doped carbon composite. Electrochemical tests revealed that the composite electrode exhibited excellent electrochemical properties in terms of specific capacity, rate performance and long term stability. Electronic supplementary information (ESI) available: XRD patterns, SEM images, SEM-EDX element mapping, TEM images, TGA analysis, N2 gas sorption measurements and electrochemical characterizations. See DOI: 10.1039/c5nr03035h

  10. THERMAL REGENERATION OF ACTIVATED CARBON

    EPA Science Inventory

    Ecologically, petrochemical wastes constitute a major hazard since waste materials contain relatively large amounts of non-biodegradable and toxic materials which may be discharged continuously. A three-part experimental study of activated carbon adsorption and thermal regenerati...

  11. N-Doped Ordered Mesoporous Carbon Originated from a Green Biological Dye for Electrochemical Sensing and High-Pressure CO2 Storage.

    PubMed

    Zhou, Shenghai; Xu, Hongbo; Yuan, Qunhui; Shen, Hangjia; Zhu, Xuefeng; Liu, Yi; Gan, Wei

    2016-01-13

    Herein, a series of nitrogen-doped ordered mesoporous carbons (NOMCs) with tunable porous structure were synthesized via a hard-template method with a green biological dye as precursor, under various carbonization temperatures (700-1100 °C). Compared with the ordered mesoporous silica-modified and unmodified electrodes, the use of electrodes coated by NOMCs (NOMC-700-NOMC-1100) resulted in enhanced signals and well-resolved oxidation peaks in electrocatalytic sensing of catechol and hydroquinone isomers, attributable to NOMCs' open porous structures and increased edge-plane defect sites on the N-doped carbon skeleton. Electrochemical sensors using NOMC-1000-modified electrode were fabricated and proved feasible in tap water sample analyses. The NOMCs were also used as sorbents for high-pressure CO2 storage. The NOMC with the highest N content exhibits the best CO2 absorption capacities of 800.8 and 387.6 mg/g at 273 and 298 K (30 bar), respectively, which is better than those of other NOMC materials and some recently reported CO2 sorbents with well-ordered 3D porous structures. Moreover, this NOMC shows higher affinity for CO2 than for N2, a benefit of its higher nitrogen content in the porous carbon framework. PMID:26653766

  12. Nanocrystal-constructed mesoporous CoFe₂O₄ nanowire arrays aligned on flexible carbon fabric as integrated anodes with enhanced lithium storage properties.

    PubMed

    Wang, Bo; Li, Songmei; Wu, Xiaoyu; Li, Bin; Liu, Jianhua; Yu, Mei

    2015-09-01

    A novel and facile two-step strategy is successfully developed for the large-scale fabrication of hierarchical mesoporous CoFe2O4 nanowire arrays (NWAs) on flexible carbon fabric as integrated anodes for highly efficient and reversible lithium storage. The synthesis involves the co-deposition of uniform bimetallic (Co, Fe) carbonate hydroxide hydrate precursor NWAs on carbon fabric and subsequent thermal transformation to spinel CoFe2O4 without damaging the morphology. The as-prepared CoFe2O4 nanowires have unique mesoporous structures, which are constructed by many interconnected nanocrystals with sizes of about 15-20 nm. The typical size of the nanowires is in the range of 70-100 nm in width and up to several micrometers in length. Such a hybrid nanostructure electrode presented here not only simplifies electrode processing, but also promises fast electron transport/collection and ion diffusion, and withstands volume variation upon prolonged charge/discharge cycling. As a result, the binder-free CoFe2O4/carbon fabric composite exhibits a high reversible capacity of 1185.75 mA h g(-1) at a current density of 200 mA g(-1), and a superior rate capability. More importantly, a reversible capacity as high as ∼950 mA h g(-1) can be retained and there is no obvious decay after 150 cycles. PMID:26219540

  13. MoS2 Nanosheets Hosted in Polydopamine-Derived Mesoporous Carbon Nanofibers as Lithium-Ion Battery Anodes: Enhanced MoS2 Capacity Utilization and Underlying Mechanism.

    PubMed

    Kong, Junhua; Zhao, Chenyang; Wei, Yuefan; Lu, Xuehong

    2015-11-01

    In this work, solid, hollow, and porous carbon nanofibers (SNFs, HNFs, and PNFs) were used as hosts to grow MoS2 nanosheets hydrothermally. The results show that the nanosheets on the surface of SNFs and HNFs are comprised of a few grains stacked together, giving direct carbon-MoS2 contact for the first grain and indirect contact for the rest. In contrast, the nanosheets inside of PNFs are of single-grain size and are distributed evenly in the mesopores of PNFs, providing efficient MoS2-carbon contact. Furthermore, the nanosheets grown on the polydopamine-derived carbon surface of HNFs and PNFs have larger interlayer spacing than those grown on polyacrylonitrile-derived carbon surface. As a result, the MoS2 nanosheets in PNFs possess the lowest charge-transfer resistance, the most accessible active sites for lithiation/delithiation, and can effectively buffer the volume variation of MoS2, leading to its best electrochemical performance as a lithium-ion battery anode among the three. The normalized reversible capacity of the MoS2 nanosheets in PNFs is about 1210 mAh g(-1) at 100 mA g(-1), showing the effective utilization of the electrochemical activity of MoS2. PMID:26461838

  14. Ionic Liquid Directed Mesoporous Carbon Nanoflakes as an Effiencient Electrode material

    PubMed Central

    Kong, Lirong; Chen, Wei

    2015-01-01

    Supercapacitors are considered to be the most promising approach to meet the pressing requirements for energy storage devices. The electrode materials for supercapacitors have close relationship with their electrochemical properties and thus become the key point to improve their energy storage efficiency. Herein, by using poly (vinylidene fluoride-co-hexafluoropropylene) and ionic liquid as the dual templates, polyacrylonitrile as the carbon precursor, a flake-like carbon material was prepared by a direct carbonization method. In this method, poly (vinylidene fluoride-co-hexafluoropropylene) worked as the separator for the formation of isolated carbon flakes while aggregated ionic liquid worked as the pore template. The obtained carbon flakes exhibited a specific capacitance of 170 F/g at 0.1 A/g, a high energy density of 12.2 Wh/kg and a high power density of 5 kW/kg at the current of 10 A/g. It also maintained a high capacitance retention capability with almost no declination after 500 charge-discharge cycles. The ionic liquid directed method developed here also provided a new idea for the preparation of hierarchically porous carbon nanomaterials. PMID:26656464

  15. Ionic Liquid Directed Mesoporous Carbon Nanoflakes as an Effiencient Electrode material

    NASA Astrophysics Data System (ADS)

    Kong, Lirong; Chen, Wei

    2015-12-01

    Supercapacitors are considered to be the most promising approach to meet the pressing requirements for energy storage devices. The electrode materials for supercapacitors have close relationship with their electrochemical properties and thus become the key point to improve their energy storage efficiency. Herein, by using poly (vinylidene fluoride-co-hexafluoropropylene) and ionic liquid as the dual templates, polyacrylonitrile as the carbon precursor, a flake-like carbon material was prepared by a direct carbonization method. In this method, poly (vinylidene fluoride-co-hexafluoropropylene) worked as the separator for the formation of isolated carbon flakes while aggregated ionic liquid worked as the pore template. The obtained carbon flakes exhibited a specific capacitance of 170 F/g at 0.1 A/g, a high energy density of 12.2 Wh/kg and a high power density of 5 kW/kg at the current of 10 A/g. It also maintained a high capacitance retention capability with almost no declination after 500 charge-discharge cycles. The ionic liquid directed method developed here also provided a new idea for the preparation of hierarchically porous carbon nanomaterials.

  16. Ionic Liquid Directed Mesoporous Carbon Nanoflakes as an Effiencient Electrode material.

    PubMed

    Kong, Lirong; Chen, Wei

    2015-01-01

    Supercapacitors are considered to be the most promising approach to meet the pressing requirements for energy storage devices. The electrode materials for supercapacitors have close relationship with their electrochemical properties and thus become the key point to improve their energy storage efficiency. Herein, by using poly (vinylidene fluoride-co-hexafluoropropylene) and ionic liquid as the dual templates, polyacrylonitrile as the carbon precursor, a flake-like carbon material was prepared by a direct carbonization method. In this method, poly (vinylidene fluoride-co-hexafluoropropylene) worked as the separator for the formation of isolated carbon flakes while aggregated ionic liquid worked as the pore template. The obtained carbon flakes exhibited a specific capacitance of 170 F/g at 0.1 A/g, a high energy density of 12.2 Wh/kg and a high power density of 5 kW/kg at the current of 10 A/g. It also maintained a high capacitance retention capability with almost no declination after 500 charge-discharge cycles. The ionic liquid directed method developed here also provided a new idea for the preparation of hierarchically porous carbon nanomaterials. PMID:26656464

  17. Controlling morphology, mesoporosity, crystallinity, and photocatalytic activity of ordered mesoporous TiO{sub 2} films prepared at low temperature

    SciTech Connect

    Elgh, Björn; Yuan, Ning; Palmqvist, Anders E. C.; Cho, Hae Sung; Terasaki, Osamu; Magerl, David; Philipp, Martine; Müller-Buschbaum, Peter; Roth, Stephan V.; Yoon, Kyung Byung

    2014-11-01

    Partly ordered mesoporous titania films with anatase crystallites incorporated into the pore walls were prepared at low temperature by spin-coating a microemulsion-based reaction solution. The effect of relative humidity employed during aging of the prepared films was studied using SEM, TEM, and grazing incidence small angle X-ray scattering to evaluate the mesoscopic order, porosity, and crystallinity of the films. The study shows unambiguously that crystal growth occurs mainly during storage of the films and proceeds at room temperature largely depending on relative humidity. Porosity, pore size, mesoscopic order, crystallinity, and photocatalytic activity of the films increased with relative humidity up to an optimum around 75%.

  18. Improvement of the activation of lipase from Candida rugosa following physical and chemical immobilization on modified mesoporous silica.

    PubMed

    Wang, Chunfeng; Li, Yanjing; Zhou, Guowei; Jiang, Xiaojie; Xu, Yunqiang; Bu, Zhaosheng

    2014-12-01

    Lipase from Candida rugosa (CRL) was chemically and physically immobilized onto four types of rod-shaped mesoporous silica (RSMS). RSMS prepared using surfactant P123 and poly(ethylene glycol) as co-templates was functionalized with (3-aminopropyl)triethoxysilane (APTES) to obtain P-RSMS by post-synthesis grafting. Tetraethoxysilane was hydrothermally co-condensed with APTES to obtain C-RSMS. A two-step process using APTES and glutaraldehyde was also performed to obtain G-RSMS. The effects of modification methods (including post-synthesis grafting and co-condensation) and glutaraldehyde on the mesoscopic order, interplanar spacing d100, cell parameter a0, mesoporous structure, and wall thickness of RSMS were studied in detail. Results showed that all samples were mesoporous materials with 2D mesostructures (p6mm). Pore size and d100 decreased, whereas the wall thickness increased after different modifications. CRL was used as a model enzyme to determine the effect of physical and chemical adsorption on loading amount and enzymatic activity. The possible mechanism of CRL immobilization on G-RSMS by chemical adsorption was systematically investigated. The chemical immobilization of CRL on G-RSMS increased the loading amount, hydrolytic activity, thermal stability, and reusability. Moreover, immobilized CRL was employed to catalyze the resolution of 2-octanol by esterification with caprylic acid. The enantiomeric excess of 2-octanol was 45.8% when the reaction was catalyzed by G-RSMS-CRL and decreased to about 38%-39% using the physically immobilized CRL, after 48 h of reaction in hexane. PMID:25491828

  19. Effect of calcination temperature on physical parameters and photocatalytic activity of mesoporous titania spheres using chitosan/poly(vinyl alcohol) hydrogel beads as a template

    NASA Astrophysics Data System (ADS)

    Jiang, R.; Zhu, H.-Y.; Chen, H.-H.; Yao, J.; Fu, Y.-Q.; Zhang, Z.-Y.; Xu, Y.-M.

    2014-11-01

    Mesoporous titania spheres were prepared by modified sol-gel method using chitosan/poly(vinyl alcohol) hydrogel beads as a template. Effects of calcination temperature on physical parameters were investigated by X-ray diffraction (XRD), N2 adsorption-desorption, Fourier transform infrared (FT-IR) spectra, thermogravimetry and differential thermal analyses (TG-DTA), high-resolution transmission electron microscope (HRTEM) and scanning electron microscopy (SEM). The photocatalytic activity of mesoporous titania spheres prepared was also evaluated by photocatalytic degradation of phenol as a model molecule under UV irradiation. With increasing calcination temperature, average crystallite size and pore size increased. In contrast, Brunauer-Emmett-Teller (BET) specific surface areas, porosity and pore volumes steadily decreased. Results of characterization proved that prepared titania spheres with highly organized pores were mesoporous structure. The photocatalytic activity of mesoporous titania spheres calcined at 500 °C was more effective than those calcined at other temperatures, which were attributed to the porous structure, large BET surface area, crystalline, and smaller crystallite size. This work may provide new insights into the preparation of novel mesoporous titania spheres and further practical applications in the treatment of wastewater.

  20. Mesoporous TiO2 nanoparticles containing Ag ion with excellent antimicrobial activity at remarkable low silver concentrations.

    PubMed

    Naik, Kshipra; Chatterjee, Amrita; Prakash, Halan; Kowshik, Meenal

    2013-04-01

    Mesoporous Ag-TiO2 nanoparticles with TiO2 homogenous anatase crystalline phase was synthesized using a one-pot sol-gel method. The sample was calcined at 100 degrees C and characterized by XRD, HR TEM, EDAX, IR spectroscopy, DRS, N2 adsorption-desorption isotherm and Brunauer-Emmett-Teller (BET) analysis. The BET surface area of the sample was 266 m2/g and the crystallite size as calculated using Scherrer formula was 3.76 nm. The Ag-TiO2 nanoparticles exhibited excellent antimicrobial activity against representative Gram-positive and Gram-negative bacterial cultures and Candida albicans. Complete inhibition of microorganisms was achieved at a very low Ag-TiO2 concentration, in the range of 1.0 to 20 microg/mL (effective Ag concentrations were 11.7 to 234 ppb) in less than 2 h under ambient conditions, without the requirement of photoactivation. Silver ion release studies showed that about 18% of silver ions were present in solution. Thus, it may be inferred that the antimicrobial activity is due to Ag ions released from the TiO2 matrix. The mesoporous nature and antimicrobial activity at low concentrations without photoactivation are important aspects which make this material an excellent candidate for potential application as disinfectant and/or antimicrobial agent. PMID:23621027

  1. Ordered mesoporous carbon film as an effective solid-phase microextraction coating for determination of benzene series from aqueous media.

    PubMed

    Jiang, Hui; Li, Jiansheng; Jiang, Mingyue; Lu, Rui; Shen, Jinyou; Sun, Xiuyun; Han, Weiqing; Wang, Lianjun

    2015-08-12

    The present work reports preparation of ordered mesoporous carbon (OMC) film supported on a graphite fiber as a new type of solid-phase microextraction (SPME) fiber for determination of benzene series from aqueous media. The strategy for the supported OMC film preparation was combined dip-coating technology with solvent evaporation-induced self-assembly (EISA) approach. A graphite fiber was immersed in an ethanol solution containing phenolic resin and Pluronic triblock copolymer. Upon solvent evaporation and subsequent pyrolysis under 700 °C, the phenolic resin and the surfactant self-assembled on the surface of the graphite fiber to form smooth OMC film. X-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen isothermal adsorption results indicate that the resultant OMC film possesses well-ordered two dimensional hexagonal mesostructure with pore diameters of 4.5 nm and BET surfaces of 630 m(2)/g. Scanning electron microscopy (SEM) studies show the supported OMC film with thickness at 8.5 μm is continuous and defect-free. The SPME efficiency of the OMC fiber was evaluated by analysis of five benzene series (benzene, toluene, ethylbenzene, p-xylene and m-xylene) from water samples by gas chromatography-flame ionization detection (GC-FID). The analysis results indicate that the prepared OMC fiber has wide linear ranges (0.5-500 μg/L), low detection limits (0.01-0.05 μg/L) and good repeatabilities (4.0-5.8% for one fiber, 2.9-8.7% for fiber-to-fiber). Compared with commercial counterparts, the OMC fiber exhibits improved extraction efficiency for benzene series and PAHs. PMID:26320962

  2. Growth of Hierarchal Mesoporous NiO Nanosheets on Carbon Cloth as Binder-free Anodes for High-performance Flexible Lithium-ion Batteries

    PubMed Central

    Long, Hu; Shi, Tielin; Hu, Hao; Jiang, Shulan; Xi, Shuang; Tang, Zirong

    2014-01-01

    Mesoporous NiO nanosheets were directly grown on three-dimensional (3D) carbon cloth substrate, which can be used as binder-free anode for lithium-ion batteries (LIBs). These mesoporous nanosheets were interconnected with each other and forming a network with interval voids, which give rise to large surface area and efficient buffering of the volume change. The integrated hierarchical electrode maintains all the advantageous features of directly building two-dimensional (2D) nanostructues on 3D conductive substrate, such as short diffusion length, strain relaxation and fast electron transport. As the LIB anode, it presents a high reversible capacity of 892.6 mAh g−1 after 120 cycles at a current density of 100 mA g−1 and 758.1 mAh g−1 at a high charging rate of 700 mA g−1 after 150 cycles. As demonstrated in this work, the hierarchical NiO nanosheets/carbon cloth also shows high flexibility, which can be directly used as the anode to build flexible LIBs. The introduced facile and low-cost method to prepare NiO nanosheets on flexible and conductive carbon cloth substrate is promising for the fabrication of high performance energy storage devices, especially for next-generation wearable electronic devices. PMID:25491432

  3. Silica-templated synthesis of ordered mesoporous tungsten carbide/graphitic carbon composites with nanocrystalline walls and high surface areas via a temperature-programmed carburization route.

    PubMed

    Wu, Zhangxiong; Yang, Yunxia; Gu, Dong; Li, Qiang; Feng, Dan; Chen, Zhenxia; Tu, Bo; Webley, Paul A; Zhao, Dongyuan

    2009-12-01

    Ordered mesostructured tungsten carbide and graphitic carbon composites (WC/C) with nanocrystalline walls are fabricated for the first time by a temperature-programmed carburization approach with phosphotungstic acid (PTA) as a precursor and mesoporous silica materials as hard templates. The mesostructure, crystal phase, and amount of deposited graphitic carbon can be conveniently tuned by controlling the silica template (SBA-15 or KIT-6), carburizing temperature (700-1000 degrees C), the PTA-loading amount, and the carburizing atmosphere (CH(4) or a CH(4)/H(2) mixture). A high level of deposited carbon is favorable for connecting and stabilizing the WC nanocrystallites to achieve high mesostructural regularity, as well as promoting the carburization reaction. Meanwhile, large pore sizes and high mesoporosity of the silica templates can promote WC-phase formation. These novel, ordered, mesoporous WC/C nanocomposites with high surface areas (74-169 m(2) g(-1)), large pore volumes (0.14-0.17 cm(3) g(-1)), narrow pore-size distributions (centered at about 3 nm), and very good oxidation resistance (up to 750 degrees C) have potential applications in fuel-cell catalysts and nanodevices. PMID:19743431

  4. Growth of Hierarchal Mesoporous NiO Nanosheets on Carbon Cloth as Binder-free Anodes for High-performance Flexible Lithium-ion Batteries

    NASA Astrophysics Data System (ADS)

    Long, Hu; Shi, Tielin; Hu, Hao; Jiang, Shulan; Xi, Shuang; Tang, Zirong

    2014-12-01

    Mesoporous NiO nanosheets were directly grown on three-dimensional (3D) carbon cloth substrate, which can be used as binder-free anode for lithium-ion batteries (LIBs). These mesoporous nanosheets were interconnected with each other and forming a network with interval voids, which give rise to large surface area and efficient buffering of the volume change. The integrated hierarchical electrode maintains all the advantageous features of directly building two-dimensional (2D) nanostructues on 3D conductive substrate, such as short diffusion length, strain relaxation and fast electron transport. As the LIB anode, it presents a high reversible capacity of 892.6 mAh g-1 after 120 cycles at a current density of 100 mA g-1 and 758.1 mAh g-1 at a high charging rate of 700 mA g-1 after 150 cycles. As demonstrated in this work, the hierarchical NiO nanosheets/carbon cloth also shows high flexibility, which can be directly used as the anode to build flexible LIBs. The introduced facile and low-cost method to prepare NiO nanosheets on flexible and conductive carbon cloth substrate is promising for the fabrication of high performance energy storage devices, especially for next-generation wearable electronic devices.

  5. Enhanced Plasmonic Resonance Energy Transfer in Mesoporous Silica-Encased Gold Nanorod for Two-Photon-Activated Photodynamic Therapy

    PubMed Central

    Chen, Nai-Tzu; Tang, Kuo-Chun; Chung, Ming-Fang; Cheng, Shih-Hsun; Huang, Ching-Mao; Chu, Chia-Hui; Chou, Pi-Tai; Souris, Jeffrey S.; Chen, Chin-Tu; Mou, Chung-Yuan; Lo, Leu-Wei

    2014-01-01

    The unique optical properties of gold nanorods (GNRs) have recently drawn considerable interest from those working in in vivo biomolecular sensing and bioimaging. Especially appealing in these applications is the plasmon-enhanced photoluminescence of GNRs induced by two-photon excitation at infrared wavelengths, owing to the significant penetration depth of infrared light in tissue. Unfortunately, many studies have also shown that often the intensity of pulsed coherent irradiation of GNRs needed results in irreversible deformation of GNRs, greatly reducing their two-photon luminescence (TPL) emission intensity. In this work we report the design, synthesis, and evaluation of mesoporous silica-encased gold nanorods (MS-GNRs) that incorporate photosensitizers (PSs) for two-photon-activated photodynamic therapy (TPA-PDT). The PSs, doped into the nano-channels of the mesoporous silica shell, can be efficiently excited via intra-particle plasmonic resonance energy transfer from the encased two-photon excited gold nanorod and further generates cytotoxic singlet oxygen for cancer eradication. In addition, due to the mechanical support provided by encapsulating mesoporous silica matrix against thermal deformation, the two-photon luminescence stability of GNRs was significantly improved; after 100 seconds of 800 nm repetitive laser pulse with the 30 times higher than average power for imaging acquisition, MS-GNR luminescence intensity exhibited ~260% better resistance to deformation than that of the uncoated gold nanorods. These results strongly suggest that MS-GNRs with embedded PSs might provide a promising photodynamic therapy for the treatment of deeply situated cancers via plasmonic resonance energy transfer. PMID:24955141

  6. Activated carbon to the rescue

    SciTech Connect

    Sen, S.

    1996-03-01

    This article describes the response to pipeline spill of ethylene dichloride (EDC) on the property of an oil company. Activated carbon cleanup proceedure was used. During delivery, changeout, transport, storage, thermal reactivation, and return delivery to the site, the carbon never came into direct contact with operating personnel or the atmosphere. More than 10,000 tones of dredge soil and 50 million gallons of surface water were processed during the emergency response.

  7. Controllable Synthesis of Mesoporous Peapod-like Co3O4@Carbon Nanotube Arrays for High-Performance Lithium-Ion Batteries.

    PubMed

    Gu, Dong; Li, Wei; Wang, Fei; Bongard, Hans; Spliethoff, Bernd; Schmidt, Wolfgang; Weidenthaler, Claudia; Xia, Yongyao; Zhao, Dongyuan; Schüth, Ferdi

    2015-06-01

    Transition metal oxides are regarded as promising anode materials for lithium-ion batteries because of their high theoretical capacities compared with commercial graphite. Unfortunately, the implementation of such novel anodes is hampered by their large volume changes during the Li(+) insertion and extraction process and their low electric conductivities. Herein, we report a specifically designed anode architecture to overcome such problems, that is, mesoporous peapod-like Co3O4@carbon nanotube arrays, which are constructed through a controllable nanocasting process. Co3O4 nanoparticles are confined exclusively in the intratubular pores of the nanotube arrays. The pores between the nanotubes are open, and thus render the Co3O4 nanoparticles accessible for effective electrolyte diffusion. Moreover, the carbon nanotubes act as a conductive network. As a result, the peapod-like Co3O4 @carbon nanotube electrode shows a high specific capacity, excellent rate capacity, and very good cycling performance. PMID:25914341

  8. Synthesis and photocatalytic activity of titania monoliths prepared with controlled macro- and mesopore structure.

    PubMed

    Drisko, Glenna L; Zelcer, Andrés; Wang, Xingdong; Caruso, Rachel A; Soler-Illia, Galo J de A A

    2012-08-01

    Herein, we report a one-pot synthesis of crack-free titania monoliths with hierarchical macro-mesoporosity and crystalline anatase walls. Bimodal macroporosity is created through the polymer-induced phase separation of poly(furfuryl alcohol). The cationic polymerization of furfuryl alcohol is performed in situ and subsequently the polymer becomes immiscible with the aqueous phase, which includes titanic acid. Addition of template, Pluronic F127, increases the mesopore volume and diameter of the resulting titania, as the poly(ethylene glycol) block interacts with the titania precursor, leading to assisted assembly of the metal oxide framework. The hydrophobic poly(propylene glycol) micelle core could itself be swollen with monomeric and oligomeric furfuryl alcohol, allowing for mesopores as large as 18 nm. Variations in synthesis parameters affect porosity; for instance furfuryl alcohol content changes the size and texture of the macropores, water content changes the grain size of the titania and Pluronic F127 content changes the size and volume of the mesopore. Morphological manipulation improves the photocatalytic degradation of methylene blue. Light can penetrate several millimeters into the porous monolith, giving these materials possible application in commercial devices. PMID:22775206

  9. Self-activated luminescent and mesoporous strontium hydroxyapatite nanorods for drug delivery.

    PubMed

    Zhang, Cuimiao; Li, Chunxia; Huang, Shanshan; Hou, Zhiyao; Cheng, Ziyong; Yang, Piaoping; Peng, Chong; Lin, Jun

    2010-04-01

    Multifunctional strontium hydroxyapatite (SrHAp) nanorods with luminescent and mesoporous properties have been successfully synthesized by a hydrothermal method. SEM and TEM images indicate that the mesoporous SrHAp samples consist of monodiperse nanorods with lengths of 120-150 nm, diameters of around 20 nm, and the mesopore size of 3-5 nm. The as-obtained SrHAp nanorods show an intense bright blue emission (centered at 432 nm, lifetime 11.6 ns, quantum efficiency: 22%), which might arise from CO(2)(*-) radical impurities in the crystal lattice under long-wavelength UV-light irradiation. Furthermore, the amount of trisodium citrate has an obvious impact on the particle size and the luminescence properties of the products, respectively. The drug storage/release test indicates that the luminescent SrHAp nanorods show a drug loading and controlled release properties for ibuprofen (IBU). Additionally, the emission intensity of SrHAp in the drug carrier system increases with the cumulative released amount of IBU, making the drug release might be easily tracked and monitored by the change of the luminescence intensity. This luminescent material may be potentially applied in the drug delivery and disease therapy fields. PMID:20122726

  10. Enhancing stability and oxidation activity of cytochrome C by immobilization in the nanochannels of mesoporous aluminosilicates.

    PubMed

    Lee, Chia-Hung; Lang, Jun; Yen, Chun-Wan; Shih, Pei-Chun; Lin, Tien-Sung; Mou, Chung-Yuan

    2005-06-30

    Hydrothermally stable and structrurally ordered mesoporous and microporous aluminosilicates with different pore sizes have been synthesized to immobilize cytochrome c (cyt c): MAS-9 (pore size 90 A), MCM-48-S (27 A), MCM-41-S (25 A), and Y zeolites (7.4 A). The amount of cyt c adsorption could be increased by the introduction of aluminum into the framework of pure silica materials. Among these mesoprous silicas (MPS), MAS-9 showed the highest loading capacity due to its large pore size. However, cyt c immobilized in MAS-9 could undergo facile unfolding during hydrothermal treatments. MCM-41-S and MCM-48-S have the pore sizes that match well the size of cyt c (25 x 25 x 37 A). Hence the adsorbed cyt c in these two medium pore size MPS have the highest hydrothermal stability and overall catalytic activity. On the other hand, the pore size of NaY zeolite is so small that cyt c is mostly adsorbed only on the outer surface and loses its enzymatic activity rapidly. The improved stability and high catalytic activity of cyt c immobilized in MPS are attributed to the electrostatic attraction between the pore surface and cyt c and the confinement provided by nanochannels. We further observed that cyt c immobilized in MPS exists in both high and low spin states, as inferred from the ESR and UV-vis studies. This is different from the native cyt c, which shows primarily the low spin state. The high spin state arises from the replacement of Met-80 ligands of heme Fe (III) by water or silanol group on silica surface, which could open up the heme groove for easy access of oxidants and substrates to iron center and facilitate the catalytic activity. In the catalytic study, MAS-9-cyt c showed the highest specific activity toward the oxidation of polycyclic aromatic hydrocarbons (PAHs), which arises from the fast mass transfer rate of reaction substrate due to its large pore size. For pinacyanol (a hydrophilic substrate), MCM-41-S-cyt c and MCM-48-S-cyt c showed higher specific activity than NaY-cyt c and MAS-9-cyt c. The result indicated that cyt c embedded in the channels of MCM-41-S and MCM-48-S was protected against unfolding and loss of activity. By increasing the concentration of the spin trapping agent, 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in ESR experiments, we showed that cyt c catalyzes a homolytic cleavage of the O-O bond of hydroperoxide and generates a protein cation radical (g = 2.00). Possible mechanisms for MPS-cyt c catalytic oxidation of hydroperoxides and PAHs are proposed based on the spectroscopic characterizations of the systems. PMID:16852515

  11. Production of activated carbons from waste tyres for low temperature NOx control.

    PubMed

    Al-Rahbi, Amal S; Williams, Paul T

    2016-03-01

    Waste tyres were pyrolysed in a bench scale reactor and the product chars were chemically activated with alkali chemical agents, KOH, K2CO3, NaOH and Na2CO3 to produce waste tyre derived activated carbons. The activated carbon products were then examined in terms of their ability to adsorb NOx (NO) at low temperature (25°C) from a simulated industrial process flue gas. This study investigates the influence of surface area and porosity of the carbons produced with the different alkali chemical activating agents on NO capture from the simulated flue gas. The influence of varying the chemical activation conditions on the porous texture and corresponding NO removal from the flue gas was studied. The activated carbon sorbents were characterized in relation to BET surface area, micropore and mesopore volumes and chemical composition. The highest NO removal efficiency for the waste tyre derived activated carbons was ∼75% which was obtained with the adsorbent treated with KOH which correlated with both the highest BET surface area and largest micropore volume. In contrast, the waste tyre derived activated carbons prepared using K2CO3, NaOH and Na2CO3 alkali activating agents appeared to have little influence on NO removal from the flue gases. The results suggest problematic waste tyres, have the potential to be converted to activated carbons with NOx removal efficiency comparable with conventionally produced carbons. PMID:26856444

  12. [Adsorption and desorption of dyes by waste-polymer-derived activated carbons].

    PubMed

    Lian, Fei; Liu, Chang; Li, Guo-Guang; Liu, Yi-Fu; Li, Yong; Zhu, Ling-Yan

    2012-01-01

    Mesoporous activated carbons with high surface area were prepared from three waste polymers, i. e., tire rubber, polyvinyl chloride (PVC) and polyethyleneterephtalate (PET), by KOH activation. The adsorption/desorption characteristics of dyes (methylene blue and methyl orange) on the carbons were studied. The effects of pH, ionic strength and surface surfactants in the solution on the dye adsorption were also investigated. The results indicated that the carbons derived from PVC and PET exhibited high surface area of 2 666 and 2 831 m2 x g(-1). Their mesopore volume were as high as 1.06 and 1.30 cm3 g(-1), respectively. 98.5% and 97.0% of methylene blue and methyl orange were removed in 15 min by PVC carbon, and that of 99.5% and 95.0% for PET carbon. The Langmuir maximum adsorption capacity to these dyes was more than 2 mmol x g(-1), much higher than that of commercial activated carbon F400. Compared with Freundlich model, the adsorption data was fitted better by Langmiur model, indicating monolayer coverage on the carbons. The adsorption was highly dependent on solution pH, ionic strength and concentration of surface surfactants. The activated carbons exhibited higher adsorption to methylene blue than that of methyl orange, and it was very hard for both of the dyes to be desorbed. The observation in this study demonstrated that activated carbons derived from polymer waste could be effective adsorbents for the treatment of wastewater with dyes. PMID:22452203

  13. Enhancement of activity and stability of the formaldehyde dehydrogenase by immobilizing onto phenyl-functionalized mesoporous silica.

    PubMed

    Masuda, Yuichi; Kugimiya, Shin-ichi; Murai, Kazuki; Hayashi, Akari; Kato, Katsuya

    2013-01-01

    Formaldehyde dehydrogenase (FDH, molecular size of 8.6 nm × 8.6 nm × 19.0 nm) was immobilized on seven types of mesoporous silica (MPS), whose pores were from 2.4 to 31.2 nm sized, and their catalytic activities were evaluated by oxidation of formaldehyde. Among MPSs, FDH immobilized on MPS-4 (pore size of 12.3 nm) showed the best catalytic activity. Enhancement of catalytic activity was obtained by immobilizing onto MPS, whose pore (mesopore) size was similar to the molecular size of FDH. In addition, FDH was immobilized on five types of organo-functionalized MPS-4. Results from assays of enzyme activity showed that FDH immobilized on phenyl-functionalized MPS-4 (MPS-4-Ph) had higher activity than FDH immobilized on non-functionalized one. Immobilized FDH on MPS-4-Ph was active for low formaldehyde concentration form 6.0 μM and more sensitive than conventional formaldehyde detectors. Stability of FDH activity was also evaluated under the various conditions, in which protein denaturation could occur by solvent treatment, such as methanol or sodium dodecyl sulfate. As a result, FDH stability was strongly improved by the immobilization on MPS materials. Further investigation using tryptophan fluorescence and circular dichroism (CD) indicated that the high-order structure of the FDH did not alter upon binding to the non-functionalized MPS surface. On the other hand, FDH immobilized on functionalized-MPS was changed by hydrophobic interaction or covalent binding. Consequently, substrate affinity was improved by the change in the structure of FDH and then the orientation of the active site. PMID:22796768

  14. Sustainable development of tyre char-based activated carbons with different textural properties for value-added applications.

    PubMed

    Hadi, Pejman; Yeung, Kit Ying; Guo, Jiaxin; Wang, Huaimin; McKay, Gordon

    2016-04-01

    This paper aims at the sustainable development of activated carbons for value-added applications from the waste tyre pyrolysis product, tyre char, in order to make pyrolysis economically favorable. Two activation process parameters, activation temperature (900, 925, 950 and 975 °C) and residence time (2, 4 and 6 h) with steam as the activating agent have been investigated. The textural properties of the produced tyre char activated carbons have been characterized by nitrogen adsorption-desorption experiments at -196 °C. The activation process has resulted in the production of mesoporous activated carbons confirmed by the existence of hysteresis loops in the N2 adsorption-desorption curves and the pore size distribution curves obtained from BJH method. The BET surface area, total pore volume and mesopore volume of the activated carbons from tyre char have been improved to 732 m(2)/g, 0.91 cm(3)/g and 0.89 cm(3)/g, respectively. It has been observed that the BET surface area, mesopore volume and total pore volume increased linearly with burnoff during activation in the range of experimental parameters studied. Thus, yield-normalized surface area, defined as the surface area of the activated carbon per gram of the precursor, has been introduced to optimize the activation conditions. Accordingly, the optimized activation conditions have been demonstrated as an activation temperature of 975 °C and an activation time of 4 h. PMID:26775155

  15. Freestanding 3D mesoporous Co₃O₄@carbon foam nanostructures for ethanol gas sensing.

    PubMed

    Li, Lei; Liu, Minmin; He, Shuijian; Chen, Wei

    2014-08-01

    Metal oxide materials have been widely used as gas-sensing platforms, and their sensing performances are largely dependent on the morphology and surface structure. Here, freestanding flower-like Co3O4 nanostructures supported on three-dimensional (3D) carbon foam (Co3O4@CF) were successfully synthesized by a facile and low-cost hydrothermal route and annealing procedure. The morphology and structure of the nanocomposites were studied by X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive spectroscopy, and scanning electron microscopy (SEM). The SEM characterizations showed that the skeleton of the porous carbon foam was fully covered by flower-like Co3O4 nanostructures. Moreover, each Co3O4 nanoflower is composed of densely packed nanoneedles with a length of ~10 μm, which can largely enhance the surface area (about 286.117 m(2)/g) for ethanol sensing. Gas sensor based on the as-synthesized 3D Co3O4@CF nanostructures was fabricated to study the sensing performance for ethanol at a temperature range from 180 to 360 °C. Due to the 3D porous structure and the improvement in sensing surface/interface, the Co3O4@CF nanostructure exhibited enhanced sensing performance for ethanol detection with low resistance, fast response and recovery time, high sensitivity, and limit of detection as low as 15 ppm at 320 °C. The present study shows that such novel 3D metal oxide/carbon hybrid nanostructures are promising platforms for gas sensing. PMID:25011608

  16. Increased photocatalytic activity of TiO2 mesoporous microspheres from codoping with transition metals and nitrogen

    DOE PAGESBeta

    Mathis, John E.; Lieffers, Justin J.; Mitra, Chandrima; Reboredo, Fernando A.; Bi, Z.; Bridges, Craig A.; Kidder, Michelle K.; Paranthaman, Mariappan Parans

    2015-11-06

    The composition of anatase TiO2 was modified by codoping using combinations of a transition metal and nitrogen in order to increase its photocatalytic activity and extend it performance in the visible region of the electromagnetic spectrum. The transition metals (Mn, Co, Ni, Cu) were added during the hydrothermal preparation of mesoporous TiO2 particles, and the nitrogen was introduced by post-annealing in flowing ammonia gas at high temperature. The samples were analyzed by SEM, XRD, BET, inductively-coupled plasma spectroscopy, and diffuse reflectance UV-vis spectroscopy. The photocatalytic activity was assessed by observing the change in methylene blue concentrations under both UV-vis andmore » visible-only light irradiation. As a result, the photocatalytic activity of the (Mn,N), (Co,N), (Cu,N), and Ni,N) codoped TiO2 was significantly enhanced relative to (N) TiO2.« less

  17. Increased photocatalytic activity of TiO2 mesoporous microspheres from codoping with transition metals and nitrogen

    SciTech Connect

    Mathis, John E.; Lieffers, Justin J.; Mitra, Chandrima; Reboredo, Fernando A.; Bi, Z.; Bridges, Craig A.; Kidder, Michelle K.; Paranthaman, Mariappan Parans

    2015-11-06

    The composition of anatase TiO2 was modified by codoping using combinations of a transition metal and nitrogen in order to increase its photocatalytic activity and extend it performance in the visible region of the electromagnetic spectrum. The transition metals (Mn, Co, Ni, Cu) were added during the hydrothermal preparation of mesoporous TiO2 particles, and the nitrogen was introduced by post-annealing in flowing ammonia gas at high temperature. The samples were analyzed by SEM, XRD, BET, inductively-coupled plasma spectroscopy, and diffuse reflectance UV-vis spectroscopy. The photocatalytic activity was assessed by observing the change in methylene blue concentrations under both UV-vis and visible-only light irradiation. As a result, the photocatalytic activity of the (Mn,N), (Co,N), (Cu,N), and Ni,N) codoped TiO2 was significantly enhanced relative to (N) TiO2.

  18. Synthesis and photocatalytic activity of co-doped mesoporous TiO 2 on Brij98/CTAB composite surfactant template

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaotong; Zhou, Guowei; Xu, Jing; Bai, Guangwei; Wang, Lei

    2010-06-01

    Using composite surfactant templates, polyoxyethylene (20) oleyl ether (Brij98) and cetyl trimethyl ammonium bromide (CTAB), as structure-directing agents, N and La co-doped mesoporous TiO 2 complex photocatalysts were synthesized successfully. The micromorphology of co-doped mesoporous TiO 2 samples was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FT-IR), energy-dispersive X-ray spectrometer (EDS) and N 2 adsorption-desorption measurements. The results indicated that the complex photocatalyst prepared with a molar ratio of Brij98:CTAB=1:1 showed a uniform pore size of ca. 7 nm and a high specific surface area ( SBET) of 279.0 m 2 g -1, and exhibited the highest photocatalytic activity for degradation of papermaking wastewater under ultra-violet light irradiation. The chemical oxygen demand (CODc r) percent degradation was about 73% in 12 h and chroma percent degradation was 100% in 8 h.

  19. Perfluoropentane-encapsulated hollow mesoporous prussian blue nanocubes for activated ultrasound imaging and photothermal therapy of cancer.

    PubMed

    Jia, Xiaoqing; Cai, Xiaojun; Chen, Yu; Wang, Shige; Xu, Huixiong; Zhang, Kun; Ma, Ming; Wu, Huixia; Shi, Jianlin; Chen, Hangrong

    2015-03-01

    Hollow mesoporous nanomaterials have gained tremendous attention in the fields of nanomedicine and nanobiotechnology. Herein, n-perfluoropentane (PFP)-encapsulated hollow mesoporous Prussian blue (HPB) nanocubes (HPB-PFP) with excellent colloidal stability have been synthesized for concurrent in vivo tumor diagnosis and regression. The HPB shell shows excellent photothermal conversion efficiency that can absorb near-infrared (NIR) laser light and convert it into heat. The generated heat can not only cause tumor ablation by raising the temperature of tumor tissue but also promote the continuous gasification and bubbling of encapsulated liquid PFP with low boiling point. These formed PFP bubbles can cause tissue impedance mismatch, thus apparently enhancing the signal of B-mode ultrasound imaging in vitro and generating an apparent echogenicity signal for tumor tissues of nude mice in vivo. Without showing observable in vitro and in vivo cytotoxicity, the designed biocompatible HPB-PFP nanotheranostics with high colloidal stability and photothermal efficiency are anticipated to find various biomedical applications in activated ultrasound imaging-guided tumor detection and therapy. PMID:25646576

  20. A facile one-pot self-assembly approach to incorporate SnOx nanoparticles in ordered mesoporous carbon with soft templating for fuel cells

    NASA Astrophysics Data System (ADS)

    Huang, Yingqiang; Zhai, Zhicheng; Luo, Zhigang; Liu, Yingju; Liang, Zhurong; Fang, Yueping

    2014-04-01

    Unique SnOx (x = 1,2)/ordered mesoporous carbon nanocomposites (denoted as SnOx/OMC) are firstly synthesized through a ‘one-pot’ synthesis together with the soft template self-assembly approach. The obtained SnOx/OMC nanocomposites with various SnOx contents exhibit uniform pore sizes between 3.9 and 4.2 nm, high specific surface areas between 497 and 595 m2 g-1, and high pore volumes between 0.39 and 0.48 cm3 g-1. With loading of Pt, Pt-SnOx/OMC with relatively low SnOx content exhibits superior electrocatalytic performance, long-term durability, and resistance to CO poisoning for methanol oxidation, as compared to Pt/OMC, PtRu/C and Pt-SnOx/C, which may be attributed not only to the synergetic effect of embedded SnOx, but also to the highly ordered mesostructure with high specific surface areas and large pore volumes affording plenty of surface area for support of Pt nanoparticles. This work supplies an efficient way to synthesize novel ordered mesoporous carbon self-supported metallic oxide as catalyst support and its further potential application to reduce the cost of catalysts in direct methanol fuel cells.

  1. Ge/GeO2-Ordered Mesoporous Carbon Nanocomposite for Rechargeable Lithium-Ion Batteries with a Long-Term Cycling Performance.

    PubMed

    Zeng, Lingxing; Huang, Xiaoxia; Chen, Xi; Zheng, Cheng; Qian, Qingrong; Chen, Qinghua; Wei, Mingdeng

    2016-01-13

    Germanium-based nanostructures are receiving intense interest in lithium-ion batteries because they have ultrahigh lithium ion storage ability. However, the Germanium-based anodes undergo the considerably large volume change during the charge/discharge processes, leading to a fast capacity fade. In the present work, a Ge/GeO2-ordered mesoporous carbon (Ge/GeO2-OMC) nanocomposite was successfully fabricated via a facile nanocasting route by using mesoporous carbon as a nanoreactor, and was then used as an anode for lithium-ion batteries. Benefited from its unique three-dimensional "meso-nano" structure, the Ge/GeO2-OMC nanocomposite exhibited large reversible capacity, excellent long-time cycling stability and high rate performance. For instance, a large reversible capacity of 1018 mA h g(-1) was obtained after 100 cycles at a current density of 0.1 A g(-1), which might be attributed to the unique structure of the Ge/GeO2-OMC nanocomposite. In addition, a reversible capacity of 492 mA h g(-1) can be retained when cycled to 500 cycles at a current density of 1 A g(-1). PMID:26651359

  2. MnO Nanoparticle@Mesoporous Carbon Composites Grown on Conducting Substrates Featuring High-performance Lithium-ion Battery, Supercapacitor and Sensor

    PubMed Central

    Wang, Tianyu; Peng, Zheng; Wang, Yuhang; Tang, Jing; Zheng, Gengfeng

    2013-01-01

    We demonstrate a facile, two-step coating/calcination approach to grow a uniform MnO nanoparticle@mesoporous carbon (MnO@C) composite on conducting substrates, by direct coating of the Mn-oleate precursor solution without any conducting/binding reagents, and subsequent thermal calcination. The monodispersed, sub-10 nm MnO nanoparticles offer high theoretical energy storage capacities and catalytic properties, and the mesoporous carbon coating allows for enhanced electrolyte transport and charge transfer towards/from MnO surface. In addition, the direct growth and attachment of the MnO@C nanocomposite in the supporting conductive substrates provide much reduced contact resistances and efficient charge transfer. These excellent features allow the use of MnO@C nanocomposites as lithium-ion battery and supercapacitor electrodes for energy storage, with high reversible capacity at large current densities, as well as excellent cycling and mechanical stabilities. Moreover, this MnO@C nanocomposite has also demonstrated a high sensitivity for H2O2 detection, and also exhibited attractive potential for the tumor cell analysis. PMID:24045767

  3. Screening of Toxic Chemicals in a Single Drop of Human Whole Blood Using Ordered Mesoporous Carbon as a Mass Spectrometry Probe.

    PubMed

    Huang, Xiu; Liu, Qian; Fu, Jianjie; Nie, Zhou; Gao, Ke; Jiang, Guibin

    2016-04-01

    Surface-enhanced laser desorption/ionization (SELDI) is a versatile and high-throughput mass spectrometry (MS) technique that uses a probe for extraction, enrichment, desorption, and ionization of target analytes. Here we report ordered mesoporous carbon as a new SELDI probe for rapid screening and identification of trace amount of toxic chemicals in a single drop of human whole blood without complicated sample preparation procedures. We demonstrate that ordered mesoporous carbon not only can selectively enrich a wide variety of low-mass toxic compounds from whole blood samples but also can be used as an excellent matrix to assist the laser desorption/ionization process of small molecules with low background noise, high repeatability, and good salt tolerance. High sensitivity (detection limits at ppt levels) and good reproducibility for typical toxic compounds were obtained. With CMK-8 as a SELDI probe, we successfully identified and screened six perfluorinated compounds in a single drop of whole blood collected from workers in a perfluorochemical plant. The method was also validated with complex samples such as human urine and environmental water samples. With distinct advantages such as simplicity, rapidness, minimal sample requirement, and high reliability, this method keeps great promise for various aspects of application. PMID:26985970

  4. Dye adsorption onto activated carbons from tyre rubber waste using surface coverage analysis.

    PubMed

    Mui, Edward L K; Cheung, W H; Valix, Marjorie; McKay, Gordon

    2010-07-15

    Two types of activated carbons from tyre char (with or without sulphuric acid treatment) were produced via carbon dioxide activation with BET surface areas in the range 59-1118 m(2)/g. Other characterisation tests include micropore and mesopore surface areas and volumes, pH, and elemental compositions, particularly heteroatoms such as nitrogen and sulphur. They were correlated to the adsorption capacity which were in the range of 0.45-0.71 mmol/g (untreated) and 0.62-0.84 mmol/g (acid-treated) for Acid Blue 25. In the case of larger-sized molecules like Acid Yellow 117, capacities were in the range of 0.23-0.42 mmol/g (untreated) and 0.29-0.40 mmol/g (acid-treated). Some tyre carbons exhibit a more superior performance than a microporous, commercial activated carbon (Calgon F400). By modelling the dye adsorption equilibrium data, the Redlich-Peterson isotherm is adopted as it has the lowest SSE. Based on the surface coverage analysis, a novel molecular orientation modelling of adsorbed dyes has been proposed and correlated with surface area and surface charge. For the acid dyes used in this study, molecules were likely to be adsorbed by the mesopore areas. PMID:20416883

  5. Enhanced mercuric chloride adsorption onto sulfur-modified activated carbons derived from waste tires.

    PubMed

    Yuan, Chung-Shin; Wang, Guangzhi; Xue, Sheng-Han; Ie, Iau-Ren; Jen, Yi-Hsiu; Tsai, Hsieh-Hung; Chen, Wei-Jin

    2012-07-01

    A number of activated carbons derived from waste tires were further impregnated by gaseous elemental sulfur at temperatures of 400 and 650 degrees C, with a carbon and sulfur mass ratio of 1:3. The capabilities of sulfur diffusing into the micropores of the activated carbons were significantly different between 400 and 650 degrees C, resulting in obvious dissimilarities in the sulfur content of the activated carbons. The sulfur-impregnated activated carbons were examined for the adsorptive capacity of gas-phase mercuric chloride (HgC1) by thermogravimetric analysis (TGA). The analytical precision of TGA was up to 10(-6) g at the inlet HgCl2 concentrations of 100, 300, and 500 microg/m3, for an adsorption time of 3 hr and an adsorption temperature of 150 degrees C, simulating the flue gas emitted from municipal solid waste (MSW) incinerators. Experimental results showed that sulfur modification can slightly reduce the specific surface area of activated carbons. High-surface-area activated carbons after sulfur modification had abundant mesopores and micropores, whereas low-surface-area activated carbons had abundant macropores and mesopores. Sulfur molecules were evenly distributed on the surface of the inner pores after sulfur modification, and the sulfur content of the activated carbons increased from 2-2.5% to 5-11%. After sulfur modification, the adsorptive capacity of HgCl2 for high-surface-area sulfurized activated carbons reached 1.557 mg/g (22 times higher than the virgin activated carbons). The injection of activated carbons was followed by fabric filtration, which is commonly used to remove HgCl2 from MSW incinerators. The residence time of activated carbons collected in the fabric filter is commonly about 1 hr, but the time required to achieve equilibrium is less than 10 min. Consequently, it is worthwhile to compare the adsorption rates of HgCl2 in the time intervals of < 10 and 10-60 min. PMID:22866581

  6. Impregnated active carbons to control atmospheric emissions: influence of impregnation methodology and raw material on the catalytic activity.

    PubMed

    Alvim-Ferraz, Maria C M; Gaspar, Carla M T B

    2005-08-15

    Previous studies have reported the influence of raw material on the catalytic activity of metal oxides impregnated in activated carbons. However, knowledge was as yet quite scarce for impregnation performed before activation. The main objective of the study here reported was the development of such knowledge. Olive stones, pinewood sawdust, nutshells, and almond shells were recycled to prepare the activated carbons. Transition metal oxides (CoO, Co3O4, and CrO3) were impregnated aiming to prepare activated carbons to be used for the complete catalytic oxidation of benzene. When impregnation was performed after activation the impregnated species were deposited on the internal surface, blocking part of the initial porous texture. When impregnation was performed before activation, the metal species acted as catalysts during the activation step, allowing better catalyst distribution on a more well-developed mesoporous texture. Co3O4 was the best catalyst and almond shells were the best support. With this catalyst/support pair a conversion of 90% was possible at 404 K, the lowest temperature of all the carbons studied. Good conversions were obtained at temperatures that guarantee carbon stability (lower than 575 K). It was concluded that activated carbon was a suitable support for metal oxide catalysts aiming for the complete oxidation of benzene, especially when a suitable porous texture is induced, by performing the impregnation step before activation. PMID:16173586

  7. Adsorption of phenol and reactive dye from aqueous solution on activated carbons derived from solid wastes.

    PubMed

    Nakagawa, Kyuya; Namba, Akio; Mukai, Shin R; Tamon, Hajime; Ariyadejwanich, Pisit; Tanthapanichakoon, Wiwut

    2004-04-01

    Activated carbons were produced from several solid wastes, namely, waste PET, waste tires, refuse derived fuel and wastes generated during lactic acid fermentation from garbage. Activated carbons having various pore size distributions were obtained by the conventional steam-activation method and via the pre-treatment method (i.e., mixture of raw materials with a metal salt, carbonization and acid treatment prior to steam-activation) that was proposed by the authors. The liquid-phase adsorption characteristics of organic compounds from aqueous solution on the activated carbons were determined to confirm the applicability of these carbons, where phenol and a reactive dye, Black5, were employed as representative adsorbates. The hydrophobic surface of the carbons prepared was also confirmed by water vapor adsorption. The characteristics of a typical commercial activated carbon were also measured and compared. It was found that the activated carbons with plentiful mesopores prepared from PET and waste tires had quite high adsorption capacity for large molecules. Therefore they are useful for wastewater treatment, especially, for removal of bulky adsorbates. PMID:15026233

  8. Neutron Scattering Studies of Liquid on or Confined in Nano- and Mesoporous Carbons, Including Carbide-Derived Carbons

    SciTech Connect

    Wesolowski, David J

    2014-07-01

    This project involved the synthesis of microporous graphitic-carbon powders with subnanometer average pore size, and very narrow pore size distributions, and the use of these materials in experimental studies of pore-fluid structure and dynamics. Samples of carbide-derived carbon powder, synthesized by extraction of the metal cations from TiC by a high temperature chlorination process, followed by high temperature vacuum annealing, were prepared by Ranjan Dash and his associates at CRADA partner Y-Carbon, Inc. The resulting material had average pore sizes ranging from 5 to 8 . These powders were used in two experiments conducted by researchers involved in the Energy Frontier Research Center Directed by David J. Wesolowski at ORNL, the Fluid Interface Reactions, Structures and Transport (FIRST) Center. FIRST-funded researchers at Drexel University collaborated with scientists at the Paul Scherrer Institute, Switzerland, to measure the expansion and contraction of the microporous carbon particles during charging and discharging of supercapactor electrodes composed of these particles (Hantell et al., 2011, Electrochemistry Communications, v. 13, pp. 1221-1224.) in an electrolyte composed of tetraethylammonium tetrafluoroborate dissolved in acetonitrile. In the second experiment, researchers at Oak Ridge National Laboratory and Drexel University conducted quasielastic neutron scattering studies of the diffusional dynamics of water imbibed into the micropores of the same material (Chathoth et al., 2011, EuroPhysics Journal, v. 95, pp. 56001/1-6). These studies helped to establish the role of pores approaching the size of the solvent and dissolved ions in altering diffusional dynamics, ion transport and physical response of conducting substrates to ion desolvation and entry into subnamometer pores.

  9. Facile and Mild Strategy to Construct Mesoporous CeO2-CuO Nanorods with Enhanced Catalytic Activity toward CO Oxidation.

    PubMed

    Chen, Guozhu; Xu, Qihui; Yang, Ying; Li, Cuncheng; Huang, Taizhong; Sun, Guoxin; Zhang, Shuxiang; Ma, Dongling; Li, Xu

    2015-10-28

    CeO2-CuO nanorods with mesoporous structure were synthesized by a facile and mild strategy, which involves an interfacial reaction between Ce2(SO4)3 precursor and NaOH ethanol solution at room temperature to obtain mesoporous CeO2 nanorods, followed by a solvothermal treatment of as-prepared CeO2 and Cu(CH3COO)2. Upon solvothermal treatment, CuO species is highly dispersed onto the CeO2 nanorod surface to form CeO2-CuO composites, which still maintain the mesoporous feature. A preliminary CO catalytic oxidation study demonstrated that the CeO2-CuO samples exhibited strikingly high catalytic activity, and a high CO conversion rate was observed without obvious loss in activity even after thermal treatment at a high temperature of 500 °C. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and hydrogen temperature-programmed reduction (H2-TPR) analysis revealed that there is a strong interaction between CeO2 and CuO. Moreover, it was found that the introduction of CuO species into CeO2 generates oxygen vacancies, which is highly likely to be responsible for high catalytic activity toward CO oxidation of the mesoporous CeO2-CuO nanorods. PMID:26455260

  10. Equilibrium and kinetics analysis of carbon dioxide capture using immobilized amine on a mesoporous silica

    SciTech Connect

    Monazam, E., Shadle, L., Pennline, H., Miller, D., Fauth, D., Hoffman, J., Gray, M.

    2012-01-01

    The equilibrium and conversion-time data on the absorption of carbon dioxide (CO{sub 2}) with amine-based solid sorbent were analyzed over the range of 303–373 K. Data on CO{sub 2} loading on amine based solid sorbent at these temperatures and CO{sub 2} partial pressure between 10 and 760 mm Hg obtained from volumetric adsorption apparatus were fitted to a simple equilibrium model to generate the different parameters (including equilibrium constant) in the model. Using these constants, a correlation was obtained to define equilibrium constant and maximum CO{sub 2} loading as a function of temperature. In this study, a shrinking core model (SCM) was applied to elucidate the relative importance of pore diffusion and surface chemical reaction in controlling the rate of reaction. Application of SCM to the data suggested a surface reaction-controlled mechanism for the temperature of up to 40°C and pore-diffusion mechanism at higher temperature.

  11. Adsorption of aqueous Cd(II) and Pb(II) on activated carbon nanopores prepared by chemical activation of doum palm shell.

    PubMed

    Gaya, Umar Ibrahim; Otene, Emmanuel; Abdullah, Abdul Halim

    2015-01-01

    Non-uniformly sized activated carbons were derived from doum palm shell, a new precursor, by carbonization in air and activation using KOH, NaOH and ZnCl2. The activated carbon fibres were characterised by X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, particle size analysis and evaluated for Cd(II) and Pb(II) removal. The 40-50 nm size, less graphitic, mesoporous NaOH activated carbon yielded high adsorption efficiency, pointing largely to the influence surface area. The performance of the KOH based activated carbon was arguably explained for the first time in terms of crystallinity. The efficiencies of the mesoporous ZnCl2-formulated activated carbon diminished due to the presence of larger particles. Batch adsorption of divalent metals revealed dependence on adsorbent dose, agitation time, pH and adsorbate concentrations with high adsorption efficiencies at optimum operating parameters. The equilibrium profiles fitted Langmuir and Freundlich isotherms, and kinetics favoured pseudo-second order model. The study demonstrated the practicability of the removal of alarming levels of cadmium and lead ions from industrial effluents. PMID:26339560

  12. Mesoporous carbon-coated Li4Ti5O12 spheres for fast Li+ ion insertion/deinsertion in lithium battery anodes

    SciTech Connect

    Navaneedhakrishnan, Jayaprakash; Moganty, Surya S.; Lou, Xiong Wen; Archer, Lynden A.

    2011-03-03

    We report on synthesis and electrochemical properties of a family of carbon-coated, mesoporous lithium titanate nanostructures (C@Li{sub 4}Ti{sub 5}O{sub 12}). Synthesized using a scalable solvothermal approach employing low-cost petroleum pitch as the carbon source, the nanostructured C@Li{sub 4}Ti{sub 5}O{sub 12} materials manifest exceptional capacity to reversibly intercalate/de-intercalate lithium at both low and high charge rates. The combination of fast electrolyte and ion transport made possible in the inherently zero-strain material, Li{sub 4}Ti{sub 5}O{sub 12}, is thought to be responsible for our observations.

  13. All-solid-state reference electrodes based on colloid-imprinted mesoporous carbon and their application in disposable paper-based potentiometric sensing devices.

    PubMed

    Hu, Jinbo; Ho, Kieu T; Zou, Xu U; Smyrl, William H; Stein, Andreas; Bhlmann, Philippe

    2015-03-01

    Reference electrodes are used in almost every electroanalytical measurement. Here, all-solid-state reference electrodes are described that employ colloid-imprinted mesoporous (CIM) carbon as solid contact and a poly(vinyl chloride) reference membrane to contact the sample. Such a reference membrane is doped with a moderately hydrophilic ionic liquid and a hydrophobic redox couple, leading to well-defined constant potentials at the interfaces of this membrane to the sample and to the solid contact, respectively. Due to the intrinsic properties of CIM carbon, reference electrodes with a CIM carbon solid contact exhibit excellent resistance to common interfering agents such as light and O2, with outstanding potential stability in continuous potentiometric measurements. The potential drift of CIM carbon-based reference electrodes without redox couple is as low as 1.7 ?V/h over 110 h, making them the most stable all-solid-state reference electrodes reported so far. To demonstrate the compatibility of CIM carbon-based reference electrodes with miniaturized potentiometric systems, these reference electrodes were integrated into paper-based potentiometric sensing devices, successfully replacing the conventional reference electrode with its reference electrolyte solution. As a proof of concept, disposable paper-based Cl(-) sensing devices that contain stencil-printed Ag/AgCl-based Cl(-) selective electrodes and CIM carbon-based reference electrodes were constructed. These sensing devices are inexpensive, easy to use, and offer highly reproducible Cl(-) measurements with sample volumes as low as 10 ?L. PMID:25630744

  14. Mesoporous ZnCo2O4 nanoflakes with bifunctional electrocatalytic activities toward efficiencies of rechargeable lithium-oxygen batteries in aprotic media

    NASA Astrophysics Data System (ADS)

    Hung, Tai-Feng; Mohamed, Saad Gomaa; Shen, Chin-Chang; Tsai, Yuan-Quei; Chang, Wen-Sheng; Liu, Ru-Shi

    2013-11-01

    This study reports the successful synthesis of ternary spinel-based ZnCo2O4 nanoflakes (NFs) with mesoporous architectures via the combination of a urea-assisted hydrothermal reaction with calcination in an air atmosphere. Owing to their favorable mesostructures and desirable bifunctional oxygen reduction and evolution activities, the resulting mesoporous ZnCo2O4 NFs yielded stable cyclability at a cut-off capacity of 500 mA h gcarbon-1 in the case of aprotic Li-O2 batteries.This study reports the successful synthesis of ternary spinel-based ZnCo2O4 nanoflakes (NFs) with mesoporous architectures via the combination of a urea-assisted hydrothermal reaction with calcination in an air atmosphere. Owing to their favorable mesostructures and desirable bifunctional oxygen reduction and evolution activities, the resulting mesoporous ZnCo2O4 NFs yielded stable cyclability at a cut-off capacity of 500 mA h gcarbon-1 in the case of aprotic Li-O2 batteries. Electronic supplementary information (ESI) available: Additional information on set-up of aprotic Li-O2 batteries testing, nitrogen adsorption-desorption analysis, CV measurement, and 1st capacity profiles of ZnCo2O4 NFs and super P-based Li-O2 batteries. See DOI: 10.1039/c3nr04271e

  15. Synthesis and characterization of mesoporous-TiO{sub 2} with enhanced photocatalytic activity for the degradation of chloro-phenol

    SciTech Connect

    Shamaila, Sajjad; Sajjad, Ahmed Khan Leghari; Chen, Feng; Zhang, Jinlong; School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550001

    2010-10-15

    Mesoporous-titania (TiO{sub 2}) photocatalysts have been synthesized using polyethylene glycol (PEG) as a template in dilute acetic acid aqueous solution by hydrothermal process. The effect of PEG molecular weights and thermal treatment on the resultant structure and photocatalytic activity are investigated. Structural and phase compositional properties of the resultant photocatalysts are characterized by transmission electron microscopy, X-ray diffraction and nitrogen sorption analysis. When the molecular weights of PEG vary from 600 to 20,000, the particle sizes of mesoporous structure decrease from 15.1 to 13.3 nm and mean pore sizes increase from 6.9 to 10.6 nm. The chemical reactions of the formation of mesoporous-TiO{sub 2} during its synthesis have been proposed and discussed. The activities of mesoporous-TiO{sub 2} photocatalysts are evaluated and compared with Degussa P-25 using chloro-phenol as a testing compound. The reaction mechanism of photodegradation is also described on the basis of high performance liquid chromatography.

  16. Photoconductivity of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    Kuriyama, K.; Dresselhaus, M. S.

    1990-08-01

    The photoconductivity is measured on a high-surface-area disordered carbon material, namely activated carbon fibers, to investigate their electronic properties. Measurements of decay time, recombination kinetics and temperature dependence of the photoconductivity generally reflect the electronic properties of a material. The material studied in this paper is a highly disordered carbon derived from a phenolic precursor, having a huge specific surface area of 1000--2000m{sup 2}/g. Our preliminary thermopower measurements suggest that this carbon material is a p-type semiconductor with an amorphous-like microstructure. The intrinsic electrical conductivity, on the order of 20S/cm at room temperature, increases with increasing temperature in the range 30--290K. In contrast with the intrinsic conductivity, the photoconductivity in vacuum decreases with increasing temperature. The recombination kinetics changes from a monomolecular process at room temperature to a biomolecular process at low temperatures. The observed decay time of the photoconductivity is {approx equal}0.3sec. The magnitude of the photoconductive signal was reduced by a factor of ten when the sample was exposed to air. The intrinsic carrier density and the activation energy for conduction are estimated to be {approx equal}10{sup 21}/cm{sup 3} and {approx equal}20meV, respectively. The majority of the induced photocarriers and of the intrinsic carriers are trapped, resulting in the long decay time of the photoconductivity and the positive temperature dependence of the conductivity.

  17. Photoconductivity of activated carbon fibers

    SciTech Connect

    Kuriyama, K.; Dresselhaus, M.S. )

    1990-08-01

    The photoconductivity is measured on a high-surface-area disordered carbon material, namely activated carbon fibers, to investigate their electronic properties. Measurements of decay time, recombination kinetics and temperature dependence of the photoconductivity generally reflect the electronic properties of a material. The material studied in this paper is a highly disordered carbon derived from a phenolic precursor, having a huge specific surface area of 1000--2000m{sup 2}/g. Our preliminary thermopower measurements suggest that this carbon material is a p-type semiconductor with an amorphous-like microstructure. The intrinsic electrical conductivity, on the order of 20S/cm at room temperature, increases with increasing temperature in the range 30--290K. In contrast with the intrinsic conductivity, the photoconductivity in vacuum decreases with increasing temperature. The recombination kinetics changes from a monomolecular process at room temperature to a biomolecular process at low temperatures. The observed decay time of the photoconductivity is {approx equal}0.3sec. The magnitude of the photoconductive signal was reduced by a factor of ten when the sample was exposed to air. The intrinsic carrier density and the activation energy for conduction are estimated to be {approx equal}10{sup 21}/cm{sup 3} and {approx equal}20meV, respectively. The majority of the induced photocarriers and of the intrinsic carriers are trapped, resulting in the long decay time of the photoconductivity and the positive temperature dependence of the conductivity. 54 refs., 11 figs., 3 tabs.

  18. One pot preparation of silver nanoparticles decorated TiO2 mesoporous microspheres with enhanced antibacterial activity.

    PubMed

    Chen, Yuemei; Deng, Yuanming; Pu, Yitao; Tang, Bijun; Su, Yikun; Tang, Jiaoning

    2016-08-01

    We report a simple "one-pot" solvothermal preparation of silver nanoparticles (Ag NPs) decorated mesoporous titania (TiO2) microspheres as an effective antibacterial agent. TBOT as Ti source was hydrolyzed and crystallized in media composed of acetic acid and ethanol, in which esterification catalyzed by TBOT occurred for in-situ "controlled water release". AgNO3 as Ag source was reduced by ethanol to form Ag NPs embedded in the TiO2 microspheres. The effect of AgNO3 and HAc on the morphology of Ag/TiO2 was investigated. The Ag/TiO2 with various Ag content showed excellent antibacterial activities with extremely low minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Escherichia coli and Staphylococcus aureus when compared with colloidal Ag NPs. PMID:27157724

  19. Hierarchical micro & mesoporous silicon carbide flakes for high-performance electrochemical capacitive energy storage

    NASA Astrophysics Data System (ADS)

    Kim, Myeongjin; Oh, Ilgeun; Kim, Jooheon

    2016-03-01

    Hierarchical micro/mesoporous silicon carbide flakes (SiCF) with a high surface area of about 1376 m2 g-1 are obtained by one-step carbonization of waste Si wafer without any chemical or physical activation. The micropores are derived from the partial evaporation of Si atoms during the carbonization process and mesopores are formed by the integration of neighboring micropores. During carbonization process, the proportion of micro and mesopores in SiCF can be controlled by carbonization time by controlling the amount of partial evaporation of Si atoms. The SiCF electrode carbonized for 8 h at 1250 °C exhibits high charge storage capacity with a specific capacitance of 203.7 F g-1 at a scan rate of 5 mV s-1 with 87.3% rate performance from 5 to 500 mV s-1 in 1 M KCl aqueous electrolyte. The outstanding electrochemical performance can be the synergistic effect of both enhanced electric double layer properties caused by micropores and reduced resistant pathways for ions diffusion in the pores as well as a large accessible surface area for ion transport/charge storage caused by mesopores. These encouraging results demonstrate that the SiCF carbonized for 8 h at 1250 °C can be promising candidate for high performance electrode materials for supercapacitors.

  20. Solvent-regenerated activated carbon

    SciTech Connect

    McLaughlin, H. )

    1988-07-01

    This report summarizes the results of a University/Industry research project, sponsored by the New York State Energy Research and Development Authority and Fluids Design Corporation. The research project studied the solvent regeneration of activated carbon. Activate carbon was used to remove trace organics from aqueous streams, then regenerated by desorbing the adsorbates with organic solvents. The project included a survey of the potential applications in New York State industries, fundamental research on the adsorption/desorption phenomena, and design of a full-scale process. The economics of the full-scale process were evaluated and compared to alternate available technologies. The result of this work is a versatile process with attractive economics. A wide range of adsorbates and solvents were found to be acceptable for this process. The design methodologies are developed and the techniques for evaluating a new application are delineated. 13 refs., 12 figs., 4 tabs.

  1. Synthesis, characterization, and application of surface-functionalized ordered mesoporous nanoparticles

    SciTech Connect

    Chung, Po-Wen

    2009-12-15

    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 delivery 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.

  2. β-Cyclodextrin anchoring onto pericarpium granati-derived magnetic mesoporous carbon for selective capture of lopid in human serum and pharmaceutical wastewater samples.

    PubMed

    Liu, Rui-Lin; Zhang, Zhi-Qi; Jing, Wang-Hui; Wang, Lu; Luo, Zhi-Min; Chang, Rui-Miao; Zeng, Ai-Guo; Du, Wei; Chang, Chun; Fu, Qiang

    2016-05-01

    Functionalized magnetic carbonaceous nanomaterials, which are important materials with many practical and research applications in biomedical, pharmaceutical and biological fields, have recently attracted much attention. In this study, a magnetic mesoporous carbon coated with β-cyclodextrin (MMC@β-CD) was synthesized for the first time from natural pericarpium granati (PG). The as-obtained MMC@β-CD has high surface areas (203m(2)g(-1)), large pore volumes (0.16cm(3)g(-1)), relatively broad mesoporous sizes (6.8nm) and a high saturation magnetization of 26.2emug(-1), which is sufficient for magnetic separation by an external magnetic field. The MMC@β-CD was used as an innovative adsorbent for magnetic solid-phase extraction of lopid via host-guest interaction prior to spectrofluorometric analysis. The proposed method was successfully applied to analyze lopid in human serum and pharmaceutical wastewater samples with recoveries in the range of 85.0-103.5% for the spiked samples. Overall, this work not only provides an inexpensive and eco-friendly method to fabricate MMC@β-CD (or MMC) from PG, but also develops a highly selective approach for capture of lopid in biological samples and environmental substances. PMID:26952464

  3. Effects of surface activation on the structural and catalytic properties of ruthenium nanoparticles supported on mesoporous silica.

    PubMed

    Ma, Xianfeng; Lin, Rui; Beuerle, Christopher; Jackson, James E; Obare, Sherine O; Ofoli, Robert Y

    2014-01-31

    Using colloid-based methods to prepare supported catalytic metallic nanoparticles (NPs) often faces the challenge of removing the stabilizer used during synthesis and activating the catalyst without modifying the particles or the support. We explored three surface activation protocols (thermal oxidation at 150 °C, thermal reduction at 350 °C, and argon-protected calcination at 650 °C) to activate ruthenium NPs supported on mesoporous silica (MSU-F), and assessed their effects on the structural and catalytic properties of the catalysts, and their activity by the aqueous phase hydrogenation of pyruvic acid. The NPs were synthesized by polyol reduction using poly-N-vinyl-2-pyrrolidone (PVP) as a stabilizer, and supported on MSU-F by sonication-assisted deposition. The NPs maintained their original morphology on the support during activation. Ar-protected calcination was the most efficient of the three for completely removing PVP from particle surfaces, and provided the highest degree of particle crystallinity and a metal dispersion comparable to commercial Ru/SiO2. Its catalytic performance was significantly higher than the other two protocols, although all three thermally activated catalysts achieved higher activity than the commercial catalyst at the same Ru loading. Post-reaction analysis also showed that the supported catalyst activated at 650 °C retained its morphology during the reaction, which is an important requirement for recyclability. PMID:24394435

  4. Adsorption studies of recalcitrant compounds of molasses spentwash on activated carbons.

    PubMed

    Figaro, S; Louisy-Louis, S; Lambert, J; Ehrhardt, J-J; Ouensanga, A; Gaspard, S

    2006-10-01

    Due to high levels of residual chemical oxygen demand (COD) in the effluent of molasses spentwash (MSW) after anaerobic treatment, acceptable COD levels for discharge cannot be achieved without some form of post-treatment. In this study, the particulate composition of molasses spentwash after anaerobic digestion (MSWD), is characterised as to its particle size distribution, using micro- and ultrafiltration and three activated carbons are characterised as to their ability to reduce significantly the COD of MSWD effluent. The activated carbons tested as adsorbent, were characterised by XPS spectroscopy, elemental analysis, surface area, pore size distribution, and acid-base titration using the Boehm's method. Adsorption of phenol, used here as a reference compound, and of some organic compounds contained in MSWD (gallic acid, tannic acid, and melanoidin, respectively), was studied. It was clearly demonstrated that an activated carbon with a significant distribution of both micropores and mesopores and a significant amount of macropores that are assumed to act as conduits providing access to micro- and mesopores, have a good adsorption efficiency for compounds such as tannic acid and melanoidins. It is a good adsorbent for melanoidin and coloured compounds of MSWD, which represents a large source of the aqueous pollution in sugar cane industries. PMID:16987542

  5. In situ Formation of a Monodispersed Spherical Mesoporous Nanosilica-Torlon Hollow-Fiber Composite for Carbon Dioxide Capture.

    PubMed

    Rownaghi, Ali A; Rezaei, Fateme; Labreche, Ying; Brennan, Patrick J; Johnson, Justin R; Li, Fuyue Stephanie; Koros, William J

    2015-10-26

    We describe a new template-free method for the in situ formation of a monodispersed spherical mesoporous nanosilica-Torlon hollow-fiber composite. A thin layer of Torlon hollow fiber that comprises silica nanoparticles was created by the in situ extrusion of a tetraethyl orthosilicate/N-methyl-2-pyrrolidone solution in a sheath layer and a Torlon polymer dope in a core support layer. This new method can be integrated easily into current hollow-fiber composite fabrication processes. The hollow-fiber composites were then functionalized with 3-aminopropyltrimethoxy silane (APS) and evaluated for their CO2 -capture performance. The resulting APS-functionalized mesoporous silica nanoparticles/Torlon hollow fibers exhibited a high CO2 equilibrium capacity of 1.5 and 1.9 mmol g(-1) at 35 and 60 °C, respectively, which is significantly higher than values for fiber sorbents without nanoparticles reported previously. PMID:26355795

  6. Adsorption of ciprofloxacin, bisphenol and 2-chlorophenol on electrospun carbon nanofibers: in comparison with powder activated carbon.

    PubMed

    Li, Xiaona; Chen, Shuo; Fan, Xinfei; Quan, Xie; Tan, Feng; Zhang, Yaobin; Gao, Jinsuo

    2015-06-01

    Carbon nanofibers (CNFs) were prepared by electrospun polyacrylonitrile (PAN) polymer solutions followed by thermal treatment. For the first time, the influence of stabilization procedure on the structure properties of CNFs was explored to improve the adsorption capacity of CNFs towards the environmental pollutants from aqueous solution. The adsorption of three organic chemicals including ciprofloxacin (CIP), bisphenol (BPA) and 2-chlorophenol (2-CP) on electrospun CNFs with high surface area of 2326m(2)/g and micro/mesoporous structure characteristics were investigated. The adsorption affinities were compared with that of the commercial powder activated carbon (PAC). The adsorption kinetics and isotherms showed that the maximum adsorption capacities (qm) of CNFs towards the three pollutants are sequenced in the order of CIP>BPA>2-CP, which are 2.6-fold (CIP), 1.6-fold (BPA) and 1.1-fold (2-CP) increase respectively in comparison with that of PAC adsorption. It was assumed that the micro/mesoporous structure of CNFs, molecular size of the pollutants and the π electron interaction play important roles on the high adsorption capacity exhibited by CNFs. In addition, electrostatic interaction and hydrophobic interaction also contribute to the adsorption of CNFs. This study demonstrates that the electrospun CNFs are promising adsorbents for the removal of pollutants from aqueous solutions. PMID:25702869

  7. Surface chemical analysis on the carbon-doped mesoporous TiO2 photocatalysts after post-thermal treatment: XPS and FTIR characterization

    NASA Astrophysics Data System (ADS)

    He, Zuoli; Que, Wenxiu; Chen, Jing; He, Yucheng; Wang, Gangfeng

    2013-07-01

    Mesoporous carbon-doped TiO2 nanoparticle was prepared by combining a hydrothermal process with a post-thermal treatment, where glucose was used as a carbon-doping source. Physicochemical properties of the carbon-doped TiO2 nanoparticle were characterized by X-ray diffraction, Scanning electron microscopy, Transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform-infrared spectroscopy, and N2 adsorption/desorption. Results indicate that post-thermal treatment of the carbon-doped TiO2 has not only little influence on the crystal size but also can increase the specific surface area and the pore volume slightly, Also a slightly increase of the specific surface area and the pore volume of the sample was due to the removing of carbonaceous organic materials during post-thermal process. And the post-thermal treatment is an effective and facile method to change the surface chemical structure of the carbon-doped TiO2 for using as photocatalysts.

  8. A functional mesoporous ionic crystal based on polyoxometalate.

    PubMed

    Kawahara, Ryosuke; Niinomi, Kazuma; Kondo, Junko N; Hibino, Mitsuhiro; Mizuno, Noritaka; Uchida, Sayaka

    2016-02-21

    A mesoporous ionic crystal is synthesized with a polyoxometalate and a macrocation with polar cyano groups. The compound possesses one-dimensional mesopores with an opening of 3.0 × 2.0 nm. The compound shows high proton conductivity and catalytic activity, which are due to the water molecules in the mesopores. PMID:26804446

  9. Redox active mesoporous hybrid materials by in situ syntheses with urea-linked triethoxysilylated phenothiazines.

    PubMed

    Zhou, Zhou; Franz, Adam W; Bay, Sarah; Sarkar, Biprajit; Seifert, Andreas; Yang, Piaoping; Wagener, Alex; Ernst, Stefan; Pagels, Markus; Müller, Thomas J J; Thiel, Werner R

    2010-09-01

    Triethoxysilyl functionalized phenothiazinyl ureas were synthesized and immobilized by in situ synthesis into mesoporous hybrid materials. The designed precursor molecules influence the structure of the final materials and the intermolecular distance of the phenothiazines. XRD and N(2) adsorption measurements indicate the presence of highly ordered two-dimensional hexagonally structured functional materials, while the incorporation of the organic compounds in the solid materials was proved by means of (13)C and (29)Si solid state NMR spectroscopy as well as by FT-IR spectroscopy. Upon oxidation with (NO)BF(4) or SbCl(5), stable phenothiazine radical cations were generated in the pores of the materials, which was detected by means of UV/Vis, emission, and EPR spectroscopies. PMID:20681016

  10. Mesoporous mixed-phase Ga{sub 2}O{sub 3}: Green synthesis and enhanced photocatalytic activity

    SciTech Connect

    Liu, Jin; Zhang, Gaoke

    2015-08-15

    Highlights: • Mixed-phase Ga{sub 2}O{sub 3} was synthesized by a facile and green method. • Mixed-phase Ga{sub 2}O{sub 3} exhibited good photocatalytic activity and stability. • The reactive species in the photocatalytic process were investigated. - Abstract: Mesoporous mixed-phase Ga{sub 2}O{sub 3} was synthesized by calcining the GaOOH precursor. The composition, crystal phase and microstructures of Ga{sub 2}O{sub 3} were characterized in detail. The phase composition of the as-prepared Ga{sub 2}O{sub 3} depended on the calcination temperature and the mixed-phase Ga{sub 2}O{sub 3} was obtained at 600–700 °C. As compared to the pure-phase α-Ga{sub 2}O{sub 3} and β-Ga{sub 2}O{sub 3}, the mixed-phase Ga{sub 2}O{sub 3} exhibited an enhanced photocatalytic property for the degradation of metronidazole solution. The heterojunction in the mixed-phase Ga{sub 2}O{sub 3} was beneficial to the separation of photogenerated electrons and holes. Moreover, the mixed-phase Ga{sub 2}O{sub 3} possessed mesopore structure, which increased more reaction sites and was in favor of the contact of metronidazole molecules with reaction sites. The recycling experiments show that the mixed-phase Ga{sub 2}O{sub 3} has good stability and can be separated easily from the reaction system.

  11. Effects of pore structure and electrolyte on the capacitive characteristics of steam- and KOH-activated carbons for supercapacitors

    NASA Astrophysics Data System (ADS)

    Wu, Feng-Chin; Tseng, Ru-Ling; Hu, Chi-Chang; Wang, Chen-Ching

    Four kinds of activated carbons (denoted as ACs) with specific surface area of ca. 1050 m 2 g -1 were fabricated from fir wood and pistachio shell by means of steam activation or chemical activation with KOH. Pore structures of ACs were characterized by a t-plot method based on N 2 adsorption isotherms. The amount of mesopores within KOH-activated carbons ranged from 9.2 to 15.3% while 33.3-49.5% of mesopores were obtained for the steam-activated carbons. The pore structure, surface functional groups, and raw materials of ACs, as well as pH and the supporting electrolyte were also found to be significant factors determining the capacitive characteristics of ACs. The excellent capacitive characteristics in both acidic and neutral media and the weak dependence of the specific capacitance on the scan rate of cyclic voltammetry (CV) for the ACs derived from the pistachio shell with steam activation (denoted as P-H 2O-AC) revealed their promising potential in the application of supercapacitors. The ACs derived from fir wood with KOH activation (denoted as F-KOH-AC), on the other hand, showed the best capacitive performance in H 2SO 4 due to excellent reversibility and high specific capacitance (180 F g -1 measured at 10 mV s -1), which is obviously larger than 100 F g -1 (a typical value of activated carbons with specific surface areas equal to/above 1000 m 2 g -1).

  12. Formation of continuous activated carbon fibers for barrier fabrics

    NASA Astrophysics Data System (ADS)

    Liang, Ying

    1997-08-01

    Commercial protective suits made of active carbon granules or nonwoven fabrics are heavy, have low moisture vapor transport rate, and are uncomfortable. Inherent problems due to construction of barrier fabrics lead to severe heat stress when worn for even short time in warm environments. One proposed method to eliminate these problems is to facilitate the construction of a fabric made of continuous activated carbon fibers (CACF). This study is directed toward investigating the possibility of developing CAFC from two precursors: aramid and fibrillated PAN fiber. It was shown in this study that Kevlar-29 fibers could be quickly carbonized and activated to CACF with high adsorptivity and relatively low weight loss. CACF with high surface area (>500 msp2/g) and reasonable tenacity (≈1g/denier) were successfully prepared from Kevlar fibers through a three-step process: pretreatment, carbonization, and activation. X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and thermal analysis were conducted to understand the evolution of physical and chemical properties during pretreatment. The influence of temperature, heating rate, and pyrolysis environment on the thermal behavior was determined by DSC and TGA/DTA and used as an indicator for optimizing the pyrolysis conditions. Surface analysis by nitrogen isotherms indicated that the resultant fibers had micropores and mesopores on the surface of CACF. This was also inferred by studies on the surface morphology through Scanning Electron Microscopy (SEM) and Scanning Tunneling Microscopy (STM). An investigation of the surface chemical structure by X-ray photoelectron spectroscopy (XPS) before and after activation and elemental analysis confirmed that adsorption of Kevlar based CACF mainly arises due to the physisorption instead of chemisorption. A multistep stabilization along with carbonization and activation was used to prepare active carbon fiber from fibrillated PAN fiber. The resultant fiber retained its fibrillar structure and provided a very high surface area, up to 1400 msp2/g, but was brittle. The characterization of the thermal behavior, mechanical properties, and surface structure of the pyrolyzed fiber at each processing step was also carried out by using various techniques, such as DSC and TGA, Instron, and SEM. These studies provide directions for preparation of CACF from novel precursors.

  13. Mesoporous carbons and polymers

    DOEpatents

    Bell, William; Dietz, Steven

    2004-05-18

    A polymer is prepared by polymerizing a polymerizable component from a mixture containing the polymerizable component and a surfactant, the surfactant and the polymerizable component being present in the mixture in a molar ratio of at least 0.2:1, having an average pore size greater than 4 nm and a density greater than 0.1 g/cc. The polymerizable component can comprise a resorcinol/formaldehyde system and the mixture can comprise an aqueous solution or the polymerizable component can comprise a divinylbenzene/styrene system and the mixture can comprise an organic solution. Alternatively, the polymerizable component can comprise vinylidene chloride or a vinylidene chloride/divinylbenzene system. The polymer may be monolithic, have a BET surface area of at least about 50 m.sup.2 /g., include a quantity of at least one metal powder, or have an electrical conductivity greater than 10 Scm.sup.-1.

  14. SBA-15 mesoporous silica activated by metal ions - Verification of molecular structure on the basis of Raman spectroscopy supported by numerical simulations

    NASA Astrophysics Data System (ADS)

    Laskowska, Magdalena; Laskowski, Lukasz; Jelonkiewicz, Jerzy

    2015-11-01

    In the paper we investigate the molecular structure of SBA-15 mesoporous silica containing propyl metal phosphonate groups, to examine the efficiency of synthesis route. Proposed method can be generalized and applied to synthesis efficiency examination in the case of relatively complex silica-based nanomaterials. Considered verification route is based on Raman scattering supported by numerical simulation. We demonstrated considered procedure on the example of SBA-15 mesoporous silica containing propyl phosphonate units activated by nickel, copper and iron ions. We showed that unambiguously verification of activation process related to phosphonic acid units incorporated inside SBA-15 silica into metal phosphonate groups is possible. On the base of comparative analysis of experimental and theoretical Raman spectra we were able to eliminate the case of incomplete or unsuccessful activation.

  15. Mesoporous Li4Ti5O12 nanoclusters anchored on super-aligned carbon nanotubes as high performance electrodes for lithium ion batteries.

    PubMed

    Sun, Li; Kong, Weibang; Wu, Hengcai; Wu, Yang; Wang, Datao; Zhao, Fei; Jiang, Kaili; Li, Qunqing; Wang, Jiaping; Fan, Shoushan

    2015-12-17

    Mesoporous lithium titanate (LTO) nanoclusters are in situ synthesized in a network of super aligned carbon nanotubes (SACNTs) via a solution-based method followed by heat treatment in air. In the LTO-CNT composite, SACNTs not only serve as the skeleton to support a binder-free electrode, but also render the composite with high conductivity, flexibility, and mechanical strength. The homogeneously dispersed LTO nanoclusters among the SACNTs allow each LTO grain to effectively access the electrolyte and the conductive network, benefiting both ion and electron transport. By the incorporation of LTO into the CNT network, mechanical reinforcement is also achieved. When serving as a negative electrode for lithium ion batteries, such a robust composite-network architecture provides the electrodes with effective charge transport and structural integrity, leading to high-performance flexible electrodes with high capacity, high rate capability, and excellent cycling stability. PMID:26646734

  16. Photocatalytic and biocidal activities of novel coating systems of mesoporous and dense TiO₂-anatase containing silver nanoparticles.

    PubMed

    Roldán, María V; de Oña, Paula; Castro, Yolanda; Durán, Alicia; Faccendini, Pablo; Lagier, Claudia; Grau, Roberto; Pellegri, Nora S

    2014-10-01

    Here we describe the development of novel nanostructured coating systems with improved photocatalytic and antibacterial activities. These systems comprise a layer of SiO2 followed by a layer of mesoporous or dense TiO2-anatase, and doping with silver nanoparticles (Ag NPs). The coatings were synthesized via a sol-gel technique by combining colloidal Ag NPs with TiO2 and SiO2 sols. The photocatalytic activity was studied through methyl orange decomposition under UV light. Results showed a great increase of photocatalytic activity by Ag NPs doping. The most active photocatalyst corresponded to the Ag-SiO2/TiO2 mesoporous system, associated with the porosity of the coatings and with the decrease of e-h recombination for the presence of Ag NPs. All the TiO2 coatings showed a strong bactericidal activity against planktonic forms of Gram-negative (enterohemorrhagic Escherichia coli) and Gram-positive (Listeria monocytogenes) pathogens, as well as a strong germicidal effect against deadly spores of human gas gangrene- and anthrax-producing bacteria (Clostridium perfringens and Bacillus anthracis, respectively). The bactericidal and sporocidal activity was improved by doping the coatings with Ag NPs, even more when nanoparticles were in the outer layer of TiO2, because they are more accessible to the environment. The mechanisms responsible for the increase of photocatalytic and bactericidal behaviors related to Ag NP doping were studied by spectroscopic ellipsometry, UV-vis spectroscopy, photoluminescence and anodic stripping voltammetry. It was found that the separation of the electron-hole pair contributed to the enhancement of photocatalysis, whereas the effect of the local electric field reinforcement was probably present. A possible involvement of a decrease of band-gap energy and dispersion by silver nanoparticles is ruled out. bactericidal efficacy was increased by Ag(+) ion release. Overall, the results included in this article show that the architecture of the films may tune photocatalytic and bactericidal properties. PMID:25175258

  17. Activated, coal-based carbon foam

    DOEpatents

    Rogers, Darren Kenneth; Plucinski, Janusz Wladyslaw

    2004-12-21

    An ablation resistant, monolithic, activated, carbon foam produced by the activation of a coal-based carbon foam through the action of carbon dioxide, ozone or some similar oxidative agent that pits and/or partially oxidizes the carbon foam skeleton, thereby significantly increasing its overall surface area and concurrently increasing its filtering ability. Such activated carbon foams are suitable for application in virtually all areas where particulate or gel form activated carbon materials have been used. Such an activated carbon foam can be fabricated, i.e. sawed, machined and otherwise shaped to fit virtually any required filtering location by simple insertion and without the need for handling the "dirty" and friable particulate activated carbon foam materials of the prior art.

  18. Activated, coal-based carbon foam

    SciTech Connect

    Rogers, Darren Kenneth; Plucinski, Janusz Wladyslaw

    2009-06-09

    An ablation resistant, monolithic, activated, carbon foam produced by the activation of a coal-based carbon foam through the action of carbon dioxide, ozone or some similar oxidative agent that pits and/or partially oxidizes the carbon foam skeleton, thereby significantly increasing its overall surface area and concurrently increasing its filtering ability. Such activated carbon foams are suitable for application in virtually all areas where particulate or gel form activated carbon materials have been used. Such an activated carbon foam can be fabricated, i.e. sawed, machined and otherwise shaped to fit virtually any required filtering location by simple insertion and without the need for handling the "dirty" and friable particulate activated carbon foam materials of the prior art.

  19. Surface chemistry in the process of coating mesoporous SiO2 onto carbon nanotubes driven by the formation of Si-O-C bonds.

    PubMed

    Paula, Amauri J; Stéfani, Diego; Souza Filho, Antonio G; Kim, Yoong Ahm; Endo, Morinobu; Alves, Oswaldo L

    2011-03-01

    The deposition of mesoporous silica (SiO(2)) on carbon nanotubes (CNTs) has opened up a wide range of assembling possibilities by exploiting the sidewall of CNTs and organosilane chemistry. The resulting systems may be suitable for applications in catalysis, energy conversion, environmental chemistry, and nanomedicine. However, to promote the condensation of silicon monomers on the nanotube without producing segregated particles, (OR)(4-x)SiO(x)(x-) units must undergo nucleophilic substitution by groups localized on the CNT sidewall during the transesterification reaction. In order to achieve this preferential attachment, we have deposited silica on oxidized carbon nanotubes (single-walled and multiwalled) in a sol-gel process that also involved the use of a soft template (cetyltrimethylammonium bromide, CTAB). In contrast to the simple approach normally used to describe the attachment of inorganic compounds on CNTs, SiO(2) nucleation on the tube is a result of nucleophilic attack mainly by hydroxyl radicals, localized in a very complex surface chemical environment, where various oxygenated groups are covalently bonded to the sidewall and carboxylated carbonaceous fragments (CCFs) are adsorbed on the tubes. Si-O-C covalent bond formation in the SiO(2)-CNT hybrids was observed even after removal of the CCFs with sodium hydroxide. By adding CTAB, and increasing the temperature, time, and initial amount of the catalyst (NH(4)OH) in the synthesis, the SiO(2) coating morphology could be changed from one of nanoparticles to mesoporous shells. Concomitantly, pore ordering was achieved by increasing the amount of CTAB. Furthermore, preferential attachment on the sidewall results mostly in CNTs with uncapped ends, having sites (carboxylic acids) that can be used for further localized reactions. PMID:21328494

  20. Mesoporous Li4Ti5O12 nanoclusters anchored on super-aligned carbon nanotubes as high performance electrodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Sun, Li; Kong, Weibang; Wu, Hengcai; Wu, Yang; Wang, Datao; Zhao, Fei; Jiang, Kaili; Li, Qunqing; Wang, Jiaping; Fan, Shoushan

    2015-12-01

    Mesoporous lithium titanate (LTO) nanoclusters are in situ synthesized in a network of super aligned carbon nanotubes (SACNTs) via a solution-based method followed by heat treatment in air. In the LTO-CNT composite, SACNTs not only serve as the skeleton to support a binder-free electrode, but also render the composite with high conductivity, flexibility, and mechanical strength. The homogeneously dispersed LTO nanoclusters among the SACNTs allow each LTO grain to effectively access the electrolyte and the conductive network, benefiting both ion and electron transport. By the incorporation of LTO into the CNT network, mechanical reinforcement is also achieved. When serving as a negative electrode for lithium ion batteries, such a robust composite-network architecture provides the electrodes with effective charge transport and structural integrity, leading to high-performance flexible electrodes with high capacity, high rate capability, and excellent cycling stability.Mesoporous lithium titanate (LTO) nanoclusters are in situ synthesized in a network of super aligned carbon nanotubes (SACNTs) via a solution-based method followed by heat treatment in air. In the LTO-CNT composite, SACNTs not only serve as the skeleton to support a binder-free electrode, but also render the composite with high conductivity, flexibility, and mechanical strength. The homogeneously dispersed LTO nanoclusters among the SACNTs allow each LTO grain to effectively access the electrolyte and the conductive network, benefiting both ion and electron transport. By the incorporation of LTO into the CNT network, mechanical reinforcement is also achieved. When serving as a negative electrode for lithium ion batteries, such a robust composite-network architecture provides the electrodes with effective charge transport and structural integrity, leading to high-performance flexible electrodes with high capacity, high rate capability, and excellent cycling stability. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06406f

  1. Mercury binding on activated carbon

    SciTech Connect

    Bihter Padak; Michael Brunetti; Amanda Lewis; Jennifer Wilcox

    2006-11-15

    Density functional theory has been employed for the modeling of activated carbon (AC) using a fused-benzene ring cluster approach. Oxygen functional groups have been investigated for their promotion of effective elemental mercury binding on AC surface sites. Lactone and carbonyl functional groups yield the highest mercury binding energies. Further, the addition of halogen atoms has been considered to the modeled surface, and has been found to increase the AC's mercury adsorption capacity. The mercury binding energies increase with the addition of the following halogen atoms, F {gt} Cl {gt} Br {gt} I, with the fluorine addition being the most promising halogen for increasing mercury adsorption.

  2. Effect of combined activation on the preparation of high porous active carbons from granulated post-consumer polyethyleneterephthalate

    NASA Astrophysics Data System (ADS)

    Sych, N. V.; Kartel, N. T.; Tsyba, N. N.; Strelko, V. V.

    2006-09-01

    Activated carbons were prepared from granulated post-consumer PET by combined activation including heat treatment with sulphuric acid (chemical activation) followed by steam activation. The effect of activation time, temperature, impregnation coefficient in the activation process was studied in order to optimize those reception parameters. One of the most important parameter in combined activation of crushed PET was found to be impregnation coefficient. It was defined that the optimal impregnation coefficient is equal 28%. Activation temperature is another variability which has a significant effect on the pore volume evolution. The increasing of activation temperature enhances the surface area and pore volumes of active carbons. The yield of final product which composes of nearly 15% is the factor limited the activation temperature above 800 °C. Textural characteristics of the samples were carried out by performing N 2 adsorption isotherm at -196 °C. The obtained active carbons were mainly micro- and mesoporous and with BET apparent surface areas of up to 1030 m 2/g. The adsorption capacity on methylene blue reaches 1.0 mmol/g, the sorption activity on iodine comes to 77%.

  3. Effect of surface phosphorus functionalities of activated carbons containing oxygen and nitrogen on electrochemical capacitance.

    PubMed

    Hulicova-Jurcakova, Denisa; Seredych, Mykola; Lu, Gao Qing; Kodiweera, N K A C; Stallworth, Phillip E; Greenbaum, Steven; Bandosz, Teresa J

    2009-05-01

    Micro/mesoporous activated carbons containing oxygen and phosphorus heteroatoms were modified by incorporation of nitrogen using melamine and urea precursors. The surface chemistry was analyzed by the means of elemental analysis, XPS, and (31)P MAS NMR. The results indicate that upon the incorporation of nitrogen at high temperatures not only new species involving carbon/nitrogen/oxygen are formed but also the phosphorous environment is significantly altered. Both urea and melamine precursors have similar effects on formation of P-N and P-C bonds. These compounds, although present in small but measurable quantities seem to affect the performance of carbons in electrochemical capacitors. With an increase in the heterogeneity of phosphorus containing species and with a decrease in the content pyrophosphates the capacitance increases and the retention ratio of the capacitor is improved. PMID:20354586

  4. Effect of surface phosphorus functionalities of activated carbons containing oxygen and nitrogen on electrochemical capacitance

    PubMed Central

    Hulicova-Jurcakova, Denisa; Seredych, Mykola; Lu, Gao Qing; Kodiweera, N.K.A.C.; Stallworth, Phillip E.; Greenbaum, Steven; Bandosz, Teresa J.

    2009-01-01

    Micro/mesoporous activated carbons containing oxygen and phosphorus heteroatoms were modified by incorporation of nitrogen using melamine and urea precursors. The surface chemistry was analyzed by the means of elemental analysis, XPS, and 31P MAS NMR. The results indicate that upon the incorporation of nitrogen at high temperatures not only new species involving carbon/nitrogen/oxygen are formed but also the phosphorous environment is significantly altered. Both urea and melamine precursors have similar effects on formation of P–N and P–C bonds. These compounds, although present in small but measurable quantities seem to affect the performance of carbons in electrochemical capacitors. With an increase in the heterogeneity of phosphorus containing species and with a decrease in the content pyrophosphates the capacitance increases and the retention ratio of the capacitor is improved. PMID:20354586

  5. Magnetic mesoporous materials for removal of environmental wastes

    SciTech Connect

    Kim, Byoung Chan; Lee, Jinwoo; Um, Wooyong; Kim, Jaeyun; Joo, Jin; Lee, Jin Hyung; Kwak, Ja Hun; Kim, Jae Hyun; Lee, Changha; Lee, Hongshin; Addleman, Raymond S.; Hyeon, Taeghwan; Gu, Man Bock; Kim, Jungbae

    2011-09-15

    We have synthesized two different magnetic mesoporous materials that can be easily separated from aqueous solutions by applying a magnetic field. Synthesized magnetic mesoporous materials, Mag-SBA-15 (magnetic ordered mesoporous silica) and Mag-OMC (magnetic ordered mesoporous carbon), have a high loading capacity of contaminants due to high surface area of the supports and high magnetic activity due to the embedded iron oxide particles. Application of surface-modified Mag-SBA-15 was investigated for the collection of mercury from water. The mercury adsorption using Mag-SBA-15 was rapid during the initial contact time and reached a steady-state condition, with an uptake of approximately 97% after 7 hours. Application of Mag-OMC for collection of organics from water, using fluorescein as an easily trackable model analyte, was explored. The fluorescein was absorbed into Mag-OMC within minutes and the fluorescent intensity of solution was completely disappeared after an hour. In another application, Mag-SBA-15 was used as a host of tyrosinase, and employed as recyclable catalytic scaffolds for tyrosinase-catalyzed biodegradation of catechol. Tyrosinase aggregates in Mag-SBA-15, prepared in a two step process of tyrosinase adsorption and crosslinking, could be used repeatedly for catechol degradation with no serious loss of enzyme activity. Considering these results of cleaning up water from toxic inorganic, organic and biochemical contaminants, magnetic mesoporous materials have a great potential to be employed for the removal of environmental contaminants and potentially for the application in large-scale wastewater treatment plants.

  6. Magnetic mesoporous materials for removal of environmental wastes.

    PubMed

    Kim, Byoung Chan; Lee, Jinwoo; Um, Wooyong; Kim, Jaeyun; Joo, Jin; Lee, Jin Hyung; Kwak, Ja Hun; Kim, Jae Hyun; Lee, Changha; Lee, Hongshin; Addleman, R Shane; Hyeon, Taeghwan; Gu, Man Bock; Kim, Jungbae

    2011-09-15

    We have synthesized two different magnetic mesoporous materials that can be easily separated from aqueous solutions by applying a magnetic field. Synthesized magnetic mesoporous materials, Mag-SBA-15 (magnetic ordered mesoporous silica) and Mag-OMC (magnetic ordered mesoporous carbon), have a high loading capacity of contaminants due to high surface area of the supports and high magnetic activity due to the embedded iron oxide particles. Application of surface-modified Mag-SBA-15 was investigated for the collection of mercury from water. The mercury adsorption using Mag-SBA-15 was rapid during the initial contact time and reached a steady-state condition, with an uptake of approximately 97% after 7h. Application of Mag-OMC for collection of organics from water, using fluorescein as an easily trackable model analyte, was explored. The fluorescein was absorbed into Mag-OMC within minutes and the fluorescent intensity of solution was completely disappeared after an hour. In another application, Mag-SBA-15 was used as a host of tyrosinase, and employed as recyclable catalytic scaffolds for tyrosinase-catalyzed biodegradation of catechol. Crosslinked tyrosinase in Mag-SBA-15, prepared in a two step process of tyrosinase adsorption and crosslinking, was stable enough for catechol degradation with no serious loss of enzyme activity. Considering these results of cleaning up water from toxic inorganic and organic contaminants, magnetic mesoporous materials have a great potential to be employed for the removal of environmental contaminants and potentially for the application in large-scale wastewater treatment plants. PMID:21752538

  7. Reducing the chlorine dioxide demand in final disinfection of drinking water treatment plants using activated carbon.

    PubMed

    Sorlini, Sabrina; Biasibetti, Michela; Collivignarelli, Maria Cristina; Crotti, Barbara Marianna

    2015-01-01

    Chlorine dioxide is one of the most widely employed chemicals in the disinfection process of a drinking water treatment plant (DWTP). The aim of this work was to evaluate the influence of the adsorption process with granular activated carbon (GAC) on the chlorine dioxide consumption in final oxidation/disinfection. A first series of tests was performed at the laboratory scale employing water samples collected at the outlet of the DWTP sand filter of Cremona (Italy). The adsorption process in batch conditions with seven different types of GAC was studied. A second series of tests was performed on water samples collected at the outlet of four GAC columns installed at the outlet of the DWTP sand filter. The results showed that the best chlorine dioxide demand (ClO2-D) reduction yields are equal to 60-80% and are achieved in the first 30 min after ClO2 addition, during the first 16 days of the column operation using a mineral, coal-based, mesoporous GAC. Therefore, this carbon removes organic compounds that are more rapidly reactive with ClO2. Moreover, a good correlation was found between the ClO2-D and UV absorbance at wavelength 254 nm using mineral carbons; therefore, the use of a mineral mesoporous GAC is an effective solution to control the high ClO2-D in the disinfection stage of a DWTP. PMID:25465650

  8. Insight into the Capacity Fading Mechanism of Amorphous Se2S5 Confined in Micro/Mesoporous Carbon Matrix in Ether-Based Electrolytes.

    PubMed

    Xu, Gui-Liang; Ma, Tianyuan; Sun, Cheng-Jun; Luo, Chao; Cheng, Lei; Ren, Yang; Heald, Steve M; Wang, Chunsheng; Curtiss, Larry; Wen, Jianguo; Miller, Dean J; Li, Tao; Zuo, Xiaobing; Petkov, Valeri; Chen, Zonghai; Amine, Khalil

    2016-04-13

    In contrast to the stable cycle performance of space confined Se-based cathodes for lithium batteries in carbonate-based electrolytes, their common capacity fading in ether-based electrolytes has been paid less attention and not yet well-addressed so far. In this work, the lithiation/delithiation of amorphous Se2S5 confined in micro/mesoporous carbon (Se2S5/MPC) cathode was investigated by in situ X-ray near edge absorption spectroscopy (XANES) and theoretical calculations. The Se2S5/MPC composite was synthesized by a modified vaporization-condensation method to ensure a good encapsulation of Se2S5 into the pores of MPC host. In situ XANES results illustrated that the lithiation/delithiation reversibility of Se component was gradually decreased in ether-based electrolytes, leading to an aggravated formation of long-chain polyselenides during cycling and further capacity decay. Moreover, ab initio calculations revealed that the binding energy of polyselenides (Li2Sen) with carbon host is in an order of Li2Se6 > Li2Se4 > Li2Se. The insights into the failure mechanism of Se-based cathode gain in this work are expected to serve as a guide for future design on high performance Se-based cathodes. PMID:27022761

  9. Sol-gel thin-film based mesoporous silica and carbon nanotubes for the determination of dopamine, uric acid and paracetamol in urine.

    PubMed

    Canevari, Thiago C; Raymundo-Pereira, Paulo A; Landers, Richard; Benvenutti, Edilson V; Machado, Sérgio A S

    2013-11-15

    This work describes the preparation, characterization and application of a hybrid material composed of disordered mesoporous silica (SiO2) modified with multiwalled carbon nanotubes (MWCNTs), obtained by the sol-gel process using HF as the catalyst. This hybrid material was characterized by N2 adsorption-desorption isotherms, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission microscopy (HR-TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). This new hybrid material was used for the construction of a thin film on a glassy carbon electrode. The modified electrode using this material was designated SiO2/MWCNT/GCE. The electrocatalytic properties of the electrode toward dopamine, uric acid and paracetamol oxidation were studied by differential pulse voltammetry. Well-defined and separated oxidation peaks were observed in phosphate buffer solution at pH 7.0, in contrast with the ill-defined peaks observed with unmodified glassy carbon electrodes. The electrode had high sensitivity for the determination of dopamine, uric acid and paracetamol, with the limits of detection obtained using statistical methods, at 0.014, 0.068 and 0.098 µmol L(-1), respectively. The electrode presented some important advantages, including enhanced physical rigidity, surface renewability by polishing and high sensitivity, allowing the simultaneous determination of these three analytes in a human urine sample. PMID:24148467

  10. Self-Volatilization Approach to Mesoporous Carbon Nanotube/Silver Nanoparticle Hybrids: The Role of Silver in Boosting Li Ion Storage.

    PubMed

    Jiang, Hao; Zhang, Haoxuan; Fu, Yao; Guo, Shaojun; Hu, Yanjie; Zhang, Ling; Liu, Yu; Liu, Honglai; Li, Chunzhong

    2016-01-26

    One of the biggest challenging issues of carbon nanomaterials for Li ion batteries (LIBs) is that they show low initial Coulombic efficiency (CE), leading to a limited specific capacity. Herein, we demonstrate a simple template self-volatilization strategy for in situ synthesis of mesoporous carbon nanotube/Ag nanoparticle (NP) hybrids (Ag-MCNTs) to boost the LIBs' performance. The key concept of Ag-MCNTs for enhancing LIBs is that a small trace of Ag NPs on MCNTS can greatly restrict the formation of a thicker solid electrolyte interphase film, which has been well verified by both transmission electron microscopy results and quantum density functional theory calculations, leading to the highest initial CE in all the reported carbon nanomaterials. This uncovered property of Ag NPs from Ag-MCNTs makes them exhibit a very high reversible capacity of 1637 mAh g(-1) after 400 discharge/charge cycles at 100 mA g(-1), approximately 5 times higher than the theoretical value of a graphite anode (372 mAh g(-1)), excellent rate capability, and long cycle life. PMID:26691283

  11. Dual-template synthesis of N-doped macro/mesoporous carbon with an open-pore structure as a metal-free catalyst for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Li, Longjun; Wang, Chih-Liang; Liao, Jin-Yun; Manthiram, Arumugam

    2015-12-01

    Dye-sensitized solar cells (DSSCs) have attracted world-wide attention due to their low cost, high conversion efficiency, and environmental friendliness. Pt catalyst is usually used as the catalyst in the counter electrode of DSSCs due to its high electrochemical catalytic activity toward tri-iodide reduction. However, the high cost and scarcity of Pt prevent its large-scale application in DSSCs. It is highly desirable to replace Pt with low-cost catalysts made from earth-abundant elements. Here, we report a dual-template synthesis of N-doped macro/mesoporous carbon (macro/meso-NC) with an open-pore structure as the catalyst in the counter electrode of DSSCs. The catalytic activity of macro/meso-NC toward tri-iodide reduction has been tested by cyclic voltammetry (CV) and photocurrent-voltage (J-V) curves. It is found that the macro/meso-NC possesses excellent electrochemical catalytic activity with higher open-circuit voltage and cell efficiency than Pt. A high energy conversion efficiency of 7.27% has been achieved based on the metal-free macro/meso-NC, demonstrating as a promising catalyst for low-cost DSSCs.

  12. Facile mesoporous template-assisted hydrothermal synthesis of ordered mesoporous magnesium silicate as an efficient adsorbent

    NASA Astrophysics Data System (ADS)

    Lu, Qingshan; Li, Qiang; Zhang, Jingjing; Li, Jingfeng; Lu, Jinhua

    2016-01-01

    Mesoporous materials with unique structure as well as special morphology have potential applications in pollutant adsorption. In this work, using mesoporous silica SBA-15 filled with carbon (C@SBA-15) as both silicon source and assisted template, the ordered mesoporous magnesium silicate (Mg3Si4O9(OH)4) has been fabricated at 140 °C by a novel and facile hydrothermal method. During the hydrothermal process, the magnesium silicate grew along the silica walls at the expense of consuming silica and deposited on the carbon surface of the C@SBA-15. Meanwhile, the rigid carbon inside the pores of the SBA-15 supported the magnesium silicate as mesoporous walls under hydrothermal condition. The obtained magnesium silicate possessed ordered mesoporous structure, high specific surface area of 446 m2/g, large pore volume of 0.84 cm3/g, and hierarchical structure assembled with ultrathin nanosheets of 15 nm in thickness. These characteristics endow the ordered mesoporous magnesium silicate with the fast adsorption rate and high adsorption capacity of 382 mg/g for methylene blue. In addition, this synthesis method opens a new approach to fabricate other ordered mesoporous silicates.

  13. Nanostructural activated carbons for hydrogen storage

    NASA Astrophysics Data System (ADS)

    Li, Suoding

    A series of nanostructured activated carbons have been synthesized from poly(ether ether ketone) (PEEK), and its derivatives. These carbons, with surface area exceeding 3000 m2/g and with average pore diameters of ≤ 20 A, are proven to be superior hydrogen storage materials, with hydrogen storage capacities up to 5.5 wt% at 77 K and 45 atm. The porous texture of these carbons was controlled via optimizing three synthetic steps: thermo-oxidation of PEEK in air, pyrolysis or carbonization of the oxidized PEEK in an inert atmosphere, and activation of the pre-carbonized PEEK with metal hydroxide. Thermo-oxidation of PEEK and carbonization process were thoroughly studied. These processes have been investigated by MDSC, FTIR, TGA and Py-MS. The pyrolysis or carbonization of PEEK involves the degradation of PEEK chains in three stages. Carbon morphology, including crystallinity and porous texture, is readily controlled by adjusting carbonization temperature. Activation of PEEK carbons, using inorganic bases and other activation agents, produces microporous carbons having a very narrow pore size distribution and an average pore diameter of ≤ 20 A. The activation control parameters including activation agent, activation temperature, time and carbon morphology have been investigated extensively. High surface area activated carbon is obtained by activating a highly amorphous carbon with a high activation agent/carbon ratio at 800°C. Theoretical calculations show that the pores with smaller diameter, especially smaller than 7 A, favor hydrogen adsorption. The experimental results confirm this fact and show that: (1) the hydrogen adsorption capacity per unit surface area at 77 K and 1 bar is larger in the smaller pores, (2) gravimetric hydrogen storage capacity (W(H2)) is directly proportional to the ultramicropore (< 7 A) volume; and (3) the volumetric hydrogen storage capacity is directly proportional to the volume fraction of ultramicropores in carbon. Hydrogen adsorption in activated carbons synthesized from PEEK and poly(ether imide) blends, poly(phenylene oxide), polybenzimidazole and lignin show similar trends. In addition, W( H2) progressively increases as surface area increases for the carbons with similar average pore diameters. Keywords. carbon, activated carbon, poly(ether ether ketone), poly(ether imide), poly(phenylene oxide), polybenzimidazole, lignin, gas adsorption, hydrogen storage

  14. Adsorption of herbicides using activated carbons

    SciTech Connect

    Derbyshire, F.; Jagtoyan, M.; Lafferty, C.; Kimber, G.

    1996-10-01

    This work describes development of a series of novel activated carbon materials and their testing for possible water treatment applications by studying the adsorption of sodium pentachlorphenolate, PCP (a common herbicide/wood preservative). Although the application of activated carbons is an established technology for the treatment of public water supplies, there is a growing need for materials with higher selectivity and adsorptive capacities as well as high abrasion resistance. The materials that will be discussed include extruded wood-derived carbons with novel pore size distributions and high hardness, as well as activated carbon fiber composites. Comparisons will be made with commercial granular water treatment carbons.

  15. Nanosized LiNi1-xFexPO4 embedded in a mesoporous carbon matrix for high-performance electrochemical water splitting.

    PubMed

    Ma, Shaojun; Zhu, Qing; Zheng, Zhi; Wang, Wenlou; Chen, Dongming

    2015-11-11

    Splitting water to produce oxygen is the key technique in the development of various energy conversion processes including metal-air batteries, fuel cells and water splitting. Herein, for the first time, we report a mesoporous LiNi1-xFexPO4@C (0 ≤ x ≤ 1) nano-structure as a highly effective catalyst for electrochemical oxygen evolution reaction (OER) through a spray dry method. In particular, the LiNi1-xFexPO4@C (3 : 1) shows superior activity to those state-of-the-art noble metal catalysts (e.g., RuO2 and IrO2), which only needs an overpotential of 311 mV to afford a current density of 10 mA cm(-2) and maintains its high catalytic activity after 1000 cycles. PMID:26368506

  16. SORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBONS

    EPA Science Inventory

    The mechanisms and rate of elemental mercury (HgO) capture by activated carbons have been studied using a bench-scale apparatus. Three types of activated carbons, two of which are thermally activated (PC-100 and FGD) and one with elemental sulfur (S) impregnated in it (HGR), were...

  17. Effect of calcination on Co-impregnated active carbon

    SciTech Connect

    Bekyarova, E.; Mehandjiev, D. . Inst. of General and Inorganic Chemistry)

    1993-11-01

    Active carbon (AC) from apricot shells with known characteristics has been impregnated with a 9.88% Co(NO[sub 3])[sub 2] [center dot] 6H[sub 2]O solution. The samples are destroyed in air at 200, 300, 400, and 550 C. The processes accompanying the thermal treatment are studied by DTA. Two processes are established during calcination of Co-impregnated active carbon: (i) destruction of the support as a result of oxidation catalyzed by the impregnated cobalt and (ii) interaction of the active phase (Co[sub 3]O[sub 4]) with the support (AC), during which Co[sub 3]O[sub 4] is reduced to CoO and Co. The presence of Co[sub 3]O[sub 4], and CoO phases is proved by X-ray measurements, while that of metal Co is established by magnetic measurements. The porous structure changes are investigated by adsorption studies. The characterization of the samples is performed by physical adsorption of N[sub 2] (77.4 K) and CO[sub 2] (273 K). The poresize distribution curves are plotted over the range 0.4--10 nm by the methods of Pierce (for the mesopores) and Medek (for the micropores). The micropore volume is determined by two independent methods: t/F method and D-R plot. The results from adsorption studies indicate a decrease of S[sub BET], V[sub mi], and, especially, the supermicropores of the samples.

  18. Adsorbed natural gas storage with activated carbons made from Illinois coals and scrap tires

    USGS Publications Warehouse

    Sun, Jielun; Brady, T.A.; Rood, M.J.; Lehmann, C.M.; Rostam-Abadi, M.; Lizzio, A.A.

    1997-01-01

    Activated carbons for natural gas storage were produced from Illinois bituminous coals (IBC-102 and IBC-106) and scrap tires by physical activation with steam or CO2 and by chemical activation with KOH, H3PO4, or ZnCl2. The products were characterized for N2-BET area, micropore volume, bulk density, pore size distribution, and volumetric methane storage capacity (Vm/Vs). Vm/Vs values for Illinois coal-derived carbons ranged from 54 to 83 cm3/cm3, which are 35-55% of a target value of 150 cm3/cm3. Both granular and pelletized carbons made with preoxidized Illinois coal gave higher micropore volumes and larger Vm/Vs values than those made without preoxidation. This confirmed that preoxidation is a desirable step in the production of carbons from caking materials. Pelletization of preoxidized IBC-106 coal, followed by steam activation, resulted in the highest Vm/Vs value. With roughly the same micropore volume, pelletization alone increased Vm/Vs of coal carbon by 10%. Tire-derived carbons had Vm/Vs values ranging from 44 to 53 cm3/cm3, lower than those of coal carbons due to their lower bulk densities. Pelletization of the tire carbons increased bulk density up to 160%. However, this increase was offset by a decrease in micropore volume of the pelletized materials, presumably due to the pellet binder. As a result, Vm/Vs values were about the same for granular and pelletized tire carbons. Compared with coal carbons, tire carbons had a higher percentage of mesopores and macropores.

  19. Guest diffusion in interpenetrating networks of micro- and mesopores.

    PubMed

    Furtado, Filipe; Galvosas, Petrik; Gonçalves, Maraisa; Kopinke, Frank-Dieter; Naumov, Sergej; Rodríguez-Reinoso, Francisco; Roland, Ulf; Valiullin, Rustem; Kärger, Jörg

    2011-03-01

    Pulsed field gradient NMR is applied for monitoring the diffusion properties of guest molecules in hierarchical pore systems after pressure variation in the external atmosphere. Following previous studies with purely mesoporous solids, also in the material containing both micro- and mesopores (activated carbon MA2), the diffusivity of the guest molecules (cyclohexane) is found to be most decisively determined by the sample "history": at a given external pressure, diffusivities are always found to be larger if they are measured after pressure decrease (i.e., on the "desorption" branch) rather than after pressure increase (adsorption branch). Simple model consideration reproduces the order of magnitude of the measured diffusivities as well as the tendencies in their relation to each other and their concentration dependence. PMID:21299204

  20. Sol-gel derived mesoporous cobalt silica catalyst: Synthesis, characterization and its activity in the oxidation of phenol

    NASA Astrophysics Data System (ADS)

    Andas, Jeyashelly; Adam, Farook; Rahman, Ismail Ab.

    2014-10-01

    Highly mesoporous cobalt silica rice husk catalysts with (5-15 wt.%) Co2+ loading were prepared via a simple sol-gel technique at room temperature. The successful insertion of cobalt ions into silica matrix was evidenced from FT-IR, NMR, XPS and AAS analyses. Preservation of the mesoporosity nature of silica upon incorporating Co2+ was confirmed from the N2-sorption studies. The topography and morphology viewed by TEM analysis differs as the cobalt concentration varies from 5 to 15 wt.%. Parallel pore channels and spherical nanoparticles of 9.44 nm were achieved for cobalt silica catalysts with 10 and 15 wt.% respectively. Cobalt catalysts were active in the liquid-phase oxidation of phenol with H2O2 as an oxygen source. The performances of the catalysts were greatly influenced by various parameters such as reaction temperature, catalyst amount, molar ratio of substrate to oxidant, nature of solvent, metal loading and homogeneous precursor salt. Water served as the best reaction medium for this oxidation system. The regeneration studies confirmed cobalt catalyst could be reused for five cycles without experiencing large loss in the conversion. Both leaching and reusability studies testified that the catalysts were truly heterogeneous.

  1. The effect of surface modification of mesoporous silica micro-rod scaffold on immune cell activation and infiltration.

    PubMed

    Li, Weiwei Aileen; Lu, Beverly Ying; Gu, Luo; Choi, Youngjin; Kim, Jaeyun; Mooney, David J

    2016-03-01

    Biomaterial scaffold based vaccines show significant potential in generating potent antigen-specific immunity. However, the role of the scaffold surface chemistry in initiating and modulating the immune response is not well understood. In this study, a mesoporous silica micro-rod (MSR) scaffold was modified with PEG, PEG-RGD and PEG-RDG groups. PEG modification significantly enhanced BMDC activation marker up-regulation and IL-1β production in vitro, and innate immune cell infiltration in vivo. PEG-RGD MSRs and PEG-RDG MSRs displayed decreased inflammation compared to PEG MSRs, and the effect was not RGD specific. Finally, the Nlrp3 inflammasome was found to be necessary for MSR stimulated IL-1β production in vitro and played a key role in regulating immune cell infiltration in vivo. These findings suggest that simply modulating the surface chemistry of a scaffold can regulate its immune cell infiltration profile and have implications for the design and development of new material based vaccines. PMID:26784009

  2. Adsorption of carbon monoxide on activated carbon tin ligand

    NASA Astrophysics Data System (ADS)

    Mohamad, A. B.; Iyuke, S. E.; Daud, W. R. W.; Kadhum, A. A. H.; Fisal, Z.; Al-Khatib, M. F.; Shariff, A. M.

    2000-09-01

    Activated carbon was impregnated with 34.57% SnCl 2·2H 2O salt and then dried at 180°C to produce AC-SnO 2 to improve its adsorptive interaction with CO. Besides the fact that activated carbon has its original different pore sizes for normal gas phase CO adsorption (as in the case of pure carbon), the impregnated carbon has additional CO adsorption ability due to the presence of O -(ads) on the active sites. AC-SnO 2 proved to be a superior adsorber of CO than pure carbon when used for H 2 purification in a PSA system. Discernibly, the high adsorptive selectivity of AC-SnO 2 towards gas phase CO portrays a good future for the applicability of this noble adsorbent, since CO has become a notorious threat to the global ecosystem due to the current level of air pollution.

  3. Studies and characterisations of various activated carbons used for carbon/carbon supercapacitors

    NASA Astrophysics Data System (ADS)

    Gamby, J.; Taberna, P. L.; Simon, P.; Fauvarque, J. F.; Chesneau, M.

    Various activated carbons from the PICA Company have been tested in supercapacitor cells in order to compare their performances. The differences measured in terms of specific capacitance and cell resistance are presented. Porosity measurements made on activated carbon powders and electrode allowed a better understanding of the electrochemical behaviour of these activated carbons. In this way, the PICACTIF SC carbon was found to be an interesting active material for supercapacitors, with a specific capacitance as high as 125 F/g.

  4. 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.

  5. Synthesis of a novel kind of carbon nanoparticle with large mesopores and macropores and its application as an oral vaccine adjuvant.

    PubMed

    Wang, Tianyi; Zou, Meijuan; Jiang, Haitao; Ji, Zhaoshuai; Gao, Ping; Cheng, Gang

    2011-12-18

    The purpose of this study is to develop a novel kind of adjuvant for oral vaccine delivery. In order to effectively prevent the degradation of antigens in the gastrointestinal tract and optimize the uptake for M cells, a novel kind of hydrophobic carbon nanoparticle (C1) with the size of 470nm was synthesized by taking silica as a template and sucrose as a carbon source. Notably, there were large mesopores and macropores mainly of 40-60nm, which made it to be excellent candidate as an antigen carrier. C1 was characterized using SEM, TEM and nitrogen adsorption. Following oral immunization with BSA loaded in C1, the IgG titer reached to a level almost equal to that of parenteral administration of antigen emulsified in Freund's complete adjuvant (FCA). Mucosal IgA was also detected in intestinal, salivary and vaginal secretions, suggesting an effective stimulation of mucosal immune response. Besides, both T-helper 1 and T-helper 2 (Th1 or Th2) mediated responses were induced. We believe that the research will help in the design of novel vaccine adjuvant for improvement their potential on modulation of immune response. PMID:22064451

  6. Single crystalline mesoporous silicon nanowires

    SciTech Connect

    Hochbaum, Allon; Dargas, Daniel; Hwang, Yun Jeong; Yang, Peidong

    2009-08-18

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. The photoluminescence of these nanowires suggest they are composed of crystalline silicon with small enough dimensions such that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices. A better understanding of this electroless route to mesoporous silicon could lead to facile and general syntheses of different narrow bandgap semiconductor nanostructures for various applications.

  7. Synthesis and photocatalytic activity of co-doped mesoporous TiO{sub 2} on Brij98/CTAB composite surfactant template

    SciTech Connect

    Zhang Xiaotong; Zhou Guowei; Xu Jing; Bai Guangwei; Wang Lei

    2010-06-15

    Using composite surfactant templates, polyoxyethylene (20) oleyl ether (Brij98) and cetyl trimethyl ammonium bromide (CTAB), as structure-directing agents, N and La co-doped mesoporous TiO{sub 2} complex photocatalysts were synthesized successfully. The micromorphology of co-doped mesoporous TiO{sub 2} samples was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FT-IR), energy-dispersive X-ray spectrometer (EDS) and N{sub 2} adsorption-desorption measurements. The results indicated that the complex photocatalyst prepared with a molar ratio of Brij98:CTAB=1:1 showed a uniform pore size of ca. 7 nm and a high specific surface area (S{sub BET}) of 279.0 m{sup 2} g{sup -1}, and exhibited the highest photocatalytic activity for degradation of papermaking wastewater under ultra-violet light irradiation. The chemical oxygen demand (CODc{sub r}) percent degradation was about 73% in 12 h and chroma percent degradation was 100% in 8 h. - Graphical abstract: CODc{sub r} percent degradation of papermaking wastewater is about 73% after 12 h over the co-doped mesoporous TiO{sub 2} prepared with a molar ratio of Brij98:CTAB=1:1.

  8. Excellent photocatalytic degradation activities of ordered mesoporous anatase TiO2-SiO2 nanocomposites to various organic contaminants.

    PubMed

    Dong, Weiyang; Sun, Yaojun; Ma, Qingwei; Zhu, Li; Hua, Weiming; Lu, Xinchun; Zhuang, Guoshun; Zhang, Shicheng; Guo, Zhigang; Zhao, Dongyuan

    2012-08-30

    Ordered 2-D hexagonal mesoporous TiO(2)-SiO(2) nanocomposites consisted of anatase TiO(2) nanocrystals and amorphous SiO(2) nanoparticles, with large mesochannels and high specific surface areas, have been extensively and detailedly evaluated using various cationic dyes (methylene blue, safranin O, crystal violet, brilliant green, basic fuchsin and rhodamine-6G), anionic dyes (acid fuchsin, orange II, reactive brilliant red X3B and acid red 1) and microcystin-LR. We use mesoporous 80TiO(2)-20SiO(2)-900 for the degradation of cationic dyes and MC-LR, due to the dominant adsorption of SiOH groups and synergistic role of coupled adsorption and photocatalytic oxidation. For anionic dyes, due to the adsorption results predominantly from TiOH groups, our strategy realizes the enhanced photocatalytic oxidation by strong surface acids and larger available specific surface area. Based on this, we prepared 90TiO(2)-10SiO(2)-700 to degrade them. The results show that our samples exhibit excellent degradation activities to all the contaminants, which are much higher than that of P25 photocatalyst. The dyes are not only decolorized promptly but degraded readily as well. It is strongly indicated that our mesoporous nanocomposites are considerably stable and reusable. These results demonstrate that our mesoporous TiO(2)-SiO(2) nanocomposites present extensive and promising application in the fast and highly efficient degradation of various organic pollutants. PMID:22749122

  9. Diffusion barriers in the kinetics of water vapor adsorption/desorption on activated carbons

    SciTech Connect

    Harding, A.W.; Foley, N.J.; Thomas, K.M.; Norman, P.R.; Francis, D.C.

    1998-07-07

    The adsorption of water vapor on a highly microporous coconut-shell-derived carbon and a mesoporous wood-derived carbon was studied. These carbons were chosen as they had markedly different porous structures. The adsorption and desorption characteristics of water vapor on the activated carbons were investigated over the relative pressure range p/p{degree} = 0--0.9 for temperatures in the range 285--313 K in a static water vapor system. The adsorption isotherms were analyzed using the Dubinin-Serpinski equation, and this provided an assessment of the polarity of the carbons. The kinetics of water vapor adsorption and desorption were studied with different amounts of preadsorbed water for set changes in pressure relative to the saturated vapor pressure (p/p{degree}). The adsorption kinetics for each relative pressure step were compared and used to calculate the activation energies for the vapor pressure increments. The kinetic results are discussed in relation to their relative position on the equilibrium isotherm and the adsorption mechanism of water vapor on activated carbons.

  10. Carboxylic acid-grafted mesoporous material and its high catalytic activity in one-pot three-component coupling reaction

    SciTech Connect

    Gomes, Ruth; Bhaumik, Asim; Dutta, Saikat

    2014-11-01

    A new carboxylic acid functionalized mesoporous organic polymer has been synthesized via in situ radical polymerization of divinylbenzene and acrylic acid using a mesoporous silica as a seed during the polymerization process under solvothermal conditions. The mesoporous material MPDVAA-1 has been thoroughly characterized emplo