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Sample records for mesoporous activated carbon

  1. Hierarchical activated mesoporous phenolic-resin-based carbons for supercapacitors.

    PubMed

    Wang, Zhao; Zhou, Min; Chen, Hao; Jiang, Jingui; Guan, Shiyou

    2014-10-01

    A series of hierarchical activated mesoporous carbons (AMCs) were prepared by the activation of highly ordered, body-centered cubic mesoporous phenolic-resin-based carbon with KOH. The effect of the KOH/carbon-weight ratio on the textural properties and capacitive performance of the AMCs was investigated in detail. An AMC prepared with a KOH/carbon-weight ratio of 6:1 possessed the largest specific surface area (1118?m(2) g(-1)), with retention of the ordered mesoporous structure, and exhibited the highest specific capacitance of 260?F?g(-1) at a current density of 0.1?A?g(-1) in 1?M H2 SO4 aqueous electrolyte. This material also showed excellent rate capability (163?F?g(-1) retained at 20?A?g(-1)) and good long-term electrochemical stability. This superior capacitive performance could be attributed to a large specific surface area and an optimized micro-mesopore structure, which not only increased the effective specific surface area for charge storage but also provided a favorable pathway for efficient ion transport. PMID:25100552

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Mesoporous carbon materials

    SciTech Connect

    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.

  7. Mesoporous carbon materials

    SciTech Connect

    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.

  8. Dye adsorption of mesoporous activated carbons produced from NaOH-pretreated rice husks.

    PubMed

    Lin, Long; Zhai, Shang-Ru; Xiao, Zuo-Yi; Song, Yu; An, Qing-Da; Song, Xiao-Wei

    2013-05-01

    In continuation of previous work on utilizing rice husks, this study aimed to prepare mesoporous activated carbons using residues of sodium hydroxide-pretreated RHs, and then examine their dye adsorption performance. The influences of the activation temperature and activation time on the surface area, pore volume, and pore radius of the activated carbon were investigated based on nitrogen adsorption/desorption isotherms and transmission electron microscopy. The adsorptive behavior of the mesoporous activated carbons obtained under optimum preparation conditions was evaluated using methyleneblue as the model adsorbate. The adsorption kinetics was studied by pseudo-first-and pseudo-second-order models, and the adsorption isotherms were studied by Langmuir and Freundlich models. The pseudo-second-order model and Langmuir isotherm were found to fit well the adsorption characteristics of the as-prepared mesoporous activated carbons. Thermodynamic data of the adsorption process were also obtained to elucidate the adsorption thermo-chemistry between the activated carbons produced from NaOH-pretreated RHs and MB molecules. PMID:23567714

  9. 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

  10. Ammonia-Activated Mesoporous Carbon Membranes for Gas Separations

    SciTech Connect

    Mahurin, Shannon Mark; Lee, Jeseung; Wang, Xiqing; Dai, Sheng

    2011-01-01

    Porous carbon membranes, which generally show improved chemical and thermal stability compared to polymer membranes, have been used in gas separations for many years. In this work, we show that the post-synthesis ammonia treatment of porous carbon at elevated temperature can improve the permeance and selectivity of these membranes for the separation of carbon dioxide and hydrocarbons from permanent gases. Hierarchically structured porous carbon membranes were exposed to ammonia gas at temperatures ranging from 850 C to 950 C for up to 10 min and the N{sub 2}, CO{sub 2}, and C{sub 3}H{sub 6} permeances were measured for these different membranes. Higher treatment temperatures and longer exposure times resulted in higher gas permeance values. In addition, CO{sub 2}/N{sub 2} and C{sub 3}H{sub 6}/N{sub 2} selectivities increased by a factor of 2 as the treatment temperature and time increased up to a temperature and time of 900 C, 10 min. Higher temperatures showed increased permeance but decreased selectivity indicating excess pore activation. Nitrogen adsorption measurements show that the ammonia treatment increased the porosity of the membrane while elemental analysis revealed the presence of nitrogen-containing surface functionalities in the treated carbon membranes. Thus, ammonia treatment at high temperature provides a controlled method to introduce both added microporosity and surface functionality to enhance gas separations performance of porous carbon membranes.

  11. 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

  12. Simple preparation and catalytic activity of Pd particles dispersed mesoporous carbons from poly(VDC/MA) containing Pd and Y compounds.

    PubMed

    Tamai, Hisashi; Ogawa, Junichi; Yasuda, Hajime

    2003-04-15

    We report a simple preparation of Pd particles dispersed mesoporous carbons. The carbons were prepared by steam activation of carbonized vinylidene chloride/methyl acrylate copolymer (poly(VDC/MA)) containing yttrium acetylacetonate (Y(acac)(3)) and palladium acetylacetonate (Pd(acac)(2)). The resulting carbons consist of high contents of mesopore and uniformly dispersed fine Pd particles. We measured the catalytic activities of the carbons obtained for hydrogenation of methyl linoleate. The Pd particles dispersed in mesoporous activated carbons obtained from poly(VDC/MA) containing both Y(acac)(3) and Pd(acac)(2) showed high catalytic activities, compared with the microporous activated carbon obtained from poly(VDC/MA) containing only Pd(acac)(2). Especially Pd particles dispersed in mesoporous carbons exhibited excellent selectivity for hydrogenation of diene (methyl linoleate) to monoene (methyl oleate). PMID:12686180

  13. 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

  14. 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

  15. The role of mesopores in MTBE removal withgranular activated carbon.

    PubMed

    Redding, Adam M; Cannon, Fred S

    2014-06-01

    This activated carbon research appraised how pore size and empty-bed contact time influenced the removal of methyl tert-butyl ether (MTBE) at part-per-billion (ppb) concentrations when MTBE was the sole organic impurity. The study compared six granular activated carbons (GACs) from three parent sources; these GACs contained a range of pore volume distributions and had uniform slurry pHs of 9.7-10.4 (i.e. the carbons' bulk surface chemistries were basic). Several of these activated carbons had been specifically tailored for enhanced sorption of trace organic compounds. In these tests, MTBE was spiked into deionized-distilled water (?pH 7); MTBE loading was measured by isotherms and by rapid small-scale column tests (RSSCTs) that simulated full-scale empty-bed contact times of 7, 14, and 28min. The results showed that both ultra-fine micropores and small-diameter mesopores were important for MTBE adsorption. Specifically, full MTBE loading during RSSCTs bore a strong correlation (R(2)=0.94) to the product (mL/gנmL/g) of pore volume ?4.06? wide and pore volume between ?22? and ?59? wide. This correlation was greater than for the product of any other pore volume combinations. Also, this product exhibited a stronger correlation than for just one or the other of these two pore ranges. This multiplicative relationship implied that both of these pore sizes were important for the optimum GAC performance of these six carbons (i.e. favorable mass transfer coupled with favorable sorption). The authors also compared MTBE mass loading during RSSCTs (?g MTBE/g GAC) to isotherm capacity (?g MTBE/g GAC). This RSSCT loading "efficiency" ranged from 28% to 96% for the six GACs; this efficiency correlated most strongly to pores that were 14-200? wide (R(2)=0.94). This correlation indicated that only those carbons with a sufficient volume of 14-200? pores could adsorb MTBE to the extent that would be predicted from isotherm data. PMID:24681276

  16. Mesoporous carbons and polymers

    DOEpatents

    Bell, William (Boulder, CO); Dietz, Steven (Denver, CO)

    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. Hollow mesoporous carbon cubes with high activity towards the electrocatalytic reduction of oxygen.

    PubMed

    Chen, Lisong; Cui, Xiangzhi; Zhang, Lingxia; Wang, Yongxia; Wang, Min; Cui, Fangming; Wei, Chenyang; Feng, Jingwei; Ge, Tongguang; Ren, Wenchao; Shi, Jianlin

    2015-02-01

    Hollow-structured mesoporous carbon cubes (HMCCs) have been successfully synthesized from carbon dioxide by a facile approach based on thermal reduction of magnesium. The approach is economical and applicable to large-scale synthesis. Notably, pyrrole-type nitrogen species are doped into the HMCCs during the synthesis in?situ, that is, without introducing a nitrogen-containing precursor. A formation mechanism of the HMCCs is proposed, and formation of the structure is attributed to MgO templates generated in?situ. Furthermore, the HMCCs are demonstrated to be a promising alternative to commercial Pt/C fuel-cell catalysts for the electrochemical oxygen reduction reaction. PMID:25619337

  18. Mesoporous carbonates and method of making

    DOEpatents

    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.

  19. 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

  20. 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

  1. 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.

  2. 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

  3. Non-aqueous hybrid supercapacitors fabricated with mesoporous TiO2 microspheres and activated carbon electrodes with superior performance

    NASA Astrophysics Data System (ADS)

    Cai, Yong; Zhao, Bote; Wang, Jie; Shao, Zongping

    2014-05-01

    Mesoporous TiO2 microspheres, synthesized by a facile template-free solvothermal method and subsequent heat treatment, are exploited as the electrode for hybrid supercapacitors. The effects of the calcination temperature on the phase composition, particulate microstructure and morphology are characterized by XRD, Raman, FE-SEM and N2 adsorption/desorption measurements. Hybrid supercapacitors utilizing the as-prepared TiO2 mesoporous microspheres as the negative electrode and activated carbon (AC) as the positive electrode in a non-aqueous electrolyte are fabricated. The electrochemical performance of these hybrid supercapacitors is studied by galvanostatic charge-discharge and cyclic voltammetry (CV). The hybrid supercapacitor built from TiO2 microspheres calcined at 400 C shows the best performance, delivering an energy density of 79.3 Wh kg-1 at a power density of 178.1 W kg-1. Even at a power density of 9.45 kW kg-1, an energy density of 31.5 Wh kg-1 is reached. These values are much higher than the AC-AC symmetric supercapacitor. In addition, the hybrid supercapacitor exhibits excellent cycling performance, retaining 98% of the initial energy density after 1000 cycles. Such outstanding electrochemical performance of the hybrid supercapacitor is attributed to the matched reaction kinetics between the two electrodes with different energy storage mechanisms.

  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 Laboratoryselfassembled mesoporous carboninto robust, efficient membrane systems for selective industrial gas separations.

  5. Enhancement of visible-light photocatalytic activity of silver and mesoporous carbon co-modified Bi2WO6

    NASA Astrophysics Data System (ADS)

    Zhao, Qian; Gong, Ming; Liu, Wangping; Mao, Yulin; Le, Shukun; Ju, Shang; Long, Fei; Liu, Xiufang; Liu, Kai; Jiang, Tingshun

    2015-03-01

    Ordered mesoporous carbon CMK-3 was prepared by hard template method using SBA-15 as template, sucrose as carbon source. Flower/sphere-like Bi2WO6 and CMK-3/Bi2WO6 photocatalysts were synthesized by hydrothermal method, and then Ag/Bi2WO6 and Ag/Bi2WO6/CMK-3 composite photocatalysts were prepared via a photoreduction process. The samples were characterized by XRD, UV-vis, TEM (HR-TEM), SEM, N2 physical adsorption and PL and their photocatalytic activities were evaluated by the photocatalytic degradation of methylene blue (MB) under visible light irradiation. The results show that both incorporating of CMK-3 and Ag loading greatly improved the photocatalytic activity of Bi2WO6, and the content of CMK-3 and silver have an impact on the photocatalytic activity of Bi2WO6. The photocatalytic activity of Ag/Bi2WO6/CMK-3 photocatalyst is superior to the activities of CMK-3/Bi2WO6 and Ag/Bi2WO6 under comparable conditions, and Ag/Bi2WO6/CMK-3 photocatalyst has high stability and is easy to be recycled. Also, the mechanism for the enhancement of the photocatalytic activity of CMK-3 and Ag co-modified Bi2WO6 was also investigated.

  6. 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.

  7. 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

  8. 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

  9. An efficient low-temperature route to nitrogen-doping and activation of mesoporous carbons for CO2 capture.

    PubMed

    Huang, Kuan; Chai, Song-Hai; Mayes, Richard T; Veith, Gabriel M; Browning, Katie L; Sakwa-Novak, Miles A; Potter, Matthew E; Jones, Christopher W; Wu, You-Ting; Dai, Sheng

    2015-11-24

    An innovative strategy for post-synthesis nitrogen-doping of mesoporous carbons (MCs) with high yields (>90%) at low temperatures (230-380 C) by using a strong base, sodium amide (NaNH2), was developed. The as-prepared N-doped MCs exhibit a significantly enhanced CO2 adsorption performance in terms of capacity and selectivity when compared to their parent MCs. PMID:26460737

  10. Carbon Nanotube Synthesis Using Mesoporous Silica Templates

    SciTech Connect

    Zheng, Feng; Liang, Liang; Gao, Yufei; Sukamto, Johanes H.; Aardahl, Chris L.

    2002-07-01

    Well-aligned carbon nanotubes (CNTs) were grown on mesoporous silica films by chemical vapor deposition (CVD). Ethylene was used as the carbon source and CVD was performed at 1023 K and atmospheric pressure. The films were doped with Fe during gelation, and three different structure directing agents were used for mesoporous silica synthesis: polyoxyethylene (10) cetyl ether (C16EO10), Pluronic tri-block copolymer (P123), and cetyltriethylammonium chloride (CTAC). A high degree of CNT alignment on C16EO10-mesoporous silica films was produced at Fe:Si molar ratio of 1.80. Similar alignment of CNTs was achieved on the other two types of films but on CTAC-mesoporous silica films, CNTs only grew parallel to the substrate surface from the cracks in the films because of the in-plane arrangement of the mesopores in such films. Considerable progress has been made in producing multi-walled carbon nanotubes (CNTs) by catalytic CVD techniques. If CNTs are to be integrated into certain useful devices, it is critical to be able to grow highly aligned arrays of CNTs with narrow size distribution and at specific locations on a substrate. Long-range alignment normal to the substrate results from steric crowding if the initial catalyst sites are sufficiently dense. Alignment may be improved with better control of the density of catalytic sites by means of a template of appropriate pore structure. The confinement of CNTs by the pores during the initial growth may also help align CNTs.

  11. 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

  12. 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

  13. 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

  14. 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

  15. Adsorption of benzene, cyclohexane and hexane on ordered mesoporous carbon.

    PubMed

    Wang, Gang; Dou, Baojuan; Zhang, Zhongshen; Wang, Junhui; Liu, Haier; Hao, Zhengping

    2015-04-01

    Ordered mesoporous carbon (OMC) with high specific surface area and large pore volume was synthesized and tested for use as an adsorbent for volatile organic compound (VOC) disposal. Benzene, cyclohexane and hexane were selected as typical adsorbates due to their different molecular sizes and extensive utilization in industrial processes. In spite of their structural differences, high adsorption amounts were achieved for all three adsorbates, as the pore size of OMC is large enough for the access of these VOCs. In addition, the unusual bimodal-like pore size distribution gives the adsorbates a higher diffusion rate compared with conventional adsorbents such as activated carbon and carbon molecular sieve. Kinetic analysis suggests that the adsorption barriers mainly originated from the difficulty of VOC vapor molecules entering the pore channels of adsorbents. Therefore, its superior adsorption ability toward VOCs, together with a high diffusion rate, makes the ordered mesoporous carbon a promising potential adsorbent for VOC disposal. PMID:25872710

  16. 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 400mg/L. The produced Langsat empty fruit bunch activated carbon (LEFBAC) was mesoporous and had high surface area of 1065.65m(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 261.2mg/g at 30C. The results from this work showed that LEFBAC can be used as outstanding material for anionic herbicide uptake from wastewater. PMID:25721981

  17. 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.

  18. The oriented growth of tungsten oxide in ordered mesoporous carbon and their electrochemical performance.

    PubMed

    Wang, Tao; Tang, Jing; Fan, Xiaoli; Zhou, Jianhua; Xue, Hairong; Guo, Hu; He, Jianping

    2014-05-21

    Electrocatalysts for hydrogen oxidation and methanol oxidation are the heart of the proton exchange membrane fuel cell. In spite of tremendous efforts, developing low-cost anodic electrocatalysts with high catalytic activity and corrosion resistance is still a great challenge. Here, we report a nanocomposite consisting of oriented WO3 nanorods grown in ordered mesoporous carbon as a high-performance functional catalyst carrier for proton exchange membrane fuel cells. As a result of the catalytic graphitization effect of tungsten compounds, the degree of graphitization and conductivity of mesoporous carbon film were improved even at a low temperature. Furthermore, compared with ordered mesoporous carbon, ordered mesoporous C-WO3 nanocomposites possess favorable hydrophilicity, excellent corrosion resistance and notable electrocatalytic activities. The unusual electrocatalytic activities arise from the ideal physical properties of the carrier and synergetic catalysis between Pt and WO3. PMID:24733640

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

    SciTech Connect

    Fulvio, Pasquale F.; Brown, Suree S.; Adcock, Jamie; Mayes, Richard T.; Guo, Bingkun; Sun, Xiao-Guang; Mahurin, Shannon M.; Veith, Gabriel M.; Dai, Sheng

    2011-09-29

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

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

    SciTech Connect

    Fulvio, Pasquale F; Dai, Sheng; Guo, Bingkun; Mahurin, Shannon Mark; Mayes, Richard T; Sun, Xiao-Guang; Veith, Gabriel M; Brown, Suree; Adcock, Jamie

    2011-01-01

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

  1. Mesoporous carbon-enriched palladium nanostructures with redox activity for enzyme-free electrochemical immunoassay of brevetoxin B.

    PubMed

    Lin, Youxiu; Zhou, Qian; Lin, Yuping; Lu, Minghua; Tang, Dianping

    2015-08-01

    A new signal amplification strategy based on mesoporous carbon-enriched palladium nanostructure (MSC-PdNS) was designed for enzyme-free electrochemical immunoassay of brevetoxin B (BTB) in marine toxins. The assay was carried out on a BTB-bovine serum albumin-functionalized electrode by using monoclonal mouse anti-BTB-labeling MSC-PdNS as the signal-transduction tag. A competitive-type assay protocol was successfully introduced to develop a high-efficiency enzyme-free immunoassay accompanying the doped palladium nanostructure into MSC-PdNS toward reduction of H2O2. Under the optimal conditions, the catalytic current decreased with the increment of BTB concentration in the range from 0.01 to 10 ng mL(-1) with a detection limit (LOD) of 5.0 pg mL(-1) BTB at the 3s(blank) criterion. The selectivity and precision were acceptable. In addition, the methodology was further validated for assaying spiked seafood samples, and consistent results between the electrochemical immunoassay and the referenced enzyme immunoassay were obtained. Importantly, the enzyme-free electrochemical immunoassay provides a promising approach for rapid screening of marine toxin because of its simplicity, low cost, sensitivity, specificity and without the need of sample pretreatment. PMID:26320787

  2. The oriented growth of tungsten oxide in ordered mesoporous carbon and their electrochemical performance

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Tang, Jing; Fan, Xiaoli; Zhou, Jianhua; Xue, Hairong; Guo, Hu; He, Jianping

    2014-04-01

    Electrocatalysts for hydrogen oxidation and methanol oxidation are the heart of the proton exchange membrane fuel cell. In spite of tremendous efforts, developing low-cost anodic electrocatalysts with high catalytic activity and corrosion resistance is still a great challenge. Here, we report a nanocomposite consisting of oriented WO3 nanorods grown in ordered mesoporous carbon as a high-performance functional catalyst carrier for proton exchange membrane fuel cells. As a result of the catalytic graphitization effect of tungsten compounds, the degree of graphitization and conductivity of mesoporous carbon film were improved even at a low temperature. Furthermore, compared with ordered mesoporous carbon, ordered mesoporous C-WO3 nanocomposites possess favorable hydrophilicity, excellent corrosion resistance and notable electrocatalytic activities. The unusual electrocatalytic activities arise from the ideal physical properties of the carrier and synergetic catalysis between Pt and WO3.Electrocatalysts for hydrogen oxidation and methanol oxidation are the heart of the proton exchange membrane fuel cell. In spite of tremendous efforts, developing low-cost anodic electrocatalysts with high catalytic activity and corrosion resistance is still a great challenge. Here, we report a nanocomposite consisting of oriented WO3 nanorods grown in ordered mesoporous carbon as a high-performance functional catalyst carrier for proton exchange membrane fuel cells. As a result of the catalytic graphitization effect of tungsten compounds, the degree of graphitization and conductivity of mesoporous carbon film were improved even at a low temperature. Furthermore, compared with ordered mesoporous carbon, ordered mesoporous C-WO3 nanocomposites possess favorable hydrophilicity, excellent corrosion resistance and notable electrocatalytic activities. The unusual electrocatalytic activities arise from the ideal physical properties of the carrier and synergetic catalysis between Pt and WO3. Electronic supplementary information (ESI) available: Additional structural characterizations and electrochemical measurements. See DOI: 10.1039/c4nr00396a

  3. 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.

  4. 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

  5. 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

  6. Mesoporous carbon for capacitive deionization of saline water.

    PubMed

    Tsouris, C; Mayes, R; Kiggans, J; Sharma, K; Yiacoumi, S; DePaoli, D; Dai, S

    2011-12-01

    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. PMID:22032802

  7. 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.

  8. 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

  9. 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

  10. Ordered mesoporous carbons obtained by a simple soft template method as sulfur immobilizers for lithium-sulfur cells.

    PubMed

    Moreno, Noelia; Caballero, Alvaro; Hernn, Lourdes; Morales, Julin; Canales-Vzquez, Jess

    2014-08-28

    Carbon materials with ordered mesoporous structures were synthesized using soft template methods and then activated by CO2 treatment. Sulfur was incorporated in these carbons via a simple chemical deposition method in aqueous solutions and the resulting composites were tested as electrodes in Li-S cells. The electrochemical results showed that well-ordered mesoporous carbons perform better than those with a random mesopore arrangement (wormhole-like mesoporous structure). The mesopore ordering yields a framework of well-connected empty sites that results in an enhancement of both the charge carrier mobility and the reversibility of the electrochemical reaction. Although the activation with CO2 partially destroys the mesopore arrangement, which adversely affects the electrode performance, it notably increases the surface area and the micropore content which improves the connectivity between the mesopores. The final observation was an irrelevant effect of the activation process at low current densities. However, at higher rates the activated carbon composite delivered higher capacities. The hierarchical pore structure formed by micro- and mesopores should guarantee the required fast mobility of the Li(+). PMID:25019261

  11. Mesoporous carbon/zirconia composites: a potential route to chemically functionalized electrically-conductive mesoporous materials.

    PubMed

    Oh, Jung-Min; Kumbhar, Amar S; Geiculescu, Olt; Creager, Stephen E

    2012-02-14

    Mesoporous nanocomposite materials in which nanoscale zirconia (ZrO(2)) particles are embedded in the carbon skeleton of a templated mesoporous carbon matrix were prepared, and the embedded zirconia sites were used to accomplish chemical functionalization of the interior surfaces of mesopores. These nanocomposite materials offer a unique combination of high porosity (e.g., ?84% void space), electrical conductivity, and surface tailorability. The ZrO(2)/carbon nanocomposites were characterized by thermogravimetric analysis, nitrogen-adsorption porosimetry, helium pychnometry, powder X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Comparison was made with templated mesoporous carbon samples prepared without addition of ZrO(2). Treatment of the nanocomposites with phenylphosphonic acid was undertaken and shown to result in robust binding of the phosphonic acid to the surface of ZrO(2) particles. Incorporation of nanoscale ZrO(2) surfaces in the mesoporous composite skeleton offers unique promise as a means for anchoring organophosphonates inside of pores through formation of robust covalent Zr-O-P bonds. PMID:22248432

  12. 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.

  13. Facile synthesis of carbon-doped mesoporous anatase TiO? for the enhanced visible-light driven photocatalysis.

    PubMed

    Liu, Juming; Zhang, Qiancheng; Yang, Jucai; Ma, Huiyan; Tade, Moses O; Wang, Shaobin; Liu, Jian

    2014-11-21

    Here we report a low-cost and facile synthesis approach for carbon-doped mesoporous anatase TiO2 by using Ti(BuO)4 as a source for both Ti and carbon through xerogel carbonization in a hypoxic atmosphere. The resultant mesoporous C-TiO2 with high crystallinity exhibits excellent photocatalytic activities for degradation of methyl orange (MO) and phenol under visible light irradiation. PMID:25266327

  14. 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.

  15. Contribution of mesopores in MgO-templated mesoporous carbons to capacitance in non-aqueous electrolytes

    NASA Astrophysics Data System (ADS)

    Kado, Yuya; Soneda, Yasushi; Yoshizawa, Noriko

    2015-02-01

    MgO-templated mesoporous carbons were fabricated by annealing trimagnesium dicitrate nonahydrate at various temperatures from 700 to 1000 C with subsequent acid leaching of MgO. The obtained carbons contained a large amount of mesopores. Performances of electric double-layer capacitors using these carbons were examined for propylene carbonate electrolyte containing 1 M tetraethylammonium tetrafluoroborate. The mesoporous carbons synthesized at higher temperatures showed better rate capabilities. AC impedance measurements indicated that high-temperature annealing of the carbon precursors and the presence of mesopores were important for high rate performance. In addition, the contribution of mesopores to capacitance was more significant at higher current densities of 30 A g-1.

  16. 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

  17. Structural influence of ordered mesoporous carbon supports for the hydrogenation of carbon monoxide to alcohols.

    PubMed

    Kim, Min-Ji; Chae, Ho-Jeong; Ha, Kyoung Su; Jeong, Kwang-Eun; Kim, Chul-Ung; Jeong, Soon-Yong; Kim, Tae-Wan

    2013-11-01

    A series of ordered mesoporous carbon materials (OMCs) possessing well-ordered nanoporosity with different mesopore structures were synthesized by the template-synthesis route. Two different pore strucutes (2-dimensional hexagonal and 3-dimensional cubic structures) and two different framework-configurations (rod-type and hollow-type carbon frameworks) are prepared by using the two different silica templates and synthetic conditions. The ordered mesoporous carbon supported promoted-rhodium catalysts were preparted by an incipient wetness method. The promoted Rh-OMC catalysts are tested by a fixed bed reactor for the catalytic conversion of syngas-to-alcohols. The characteristics of the promoted Rh-OMCs catalysts were scrutinized through a series of different techniques, including transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and N2 sorption analysis, and the catalytic performance was tested in a fixed-bed reactor. It was found that the promoted Rh-OMC catalysts exhibited the different catalytic activity and selectivity of alcohols, which could be attributed to the size of metal nanoparticles being confined by the different mesostructure of OMCs. PMID:24245283

  18. 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

  19. Low-temperature fabrication of mesoporous solid strong bases by using multifunction of a carbon interlayer.

    PubMed

    Liu, Xiao-Yan; Sun, Lin-Bing; Liu, Xiao-Dan; Li, Ai-Guo; Lu, Feng; Liu, Xiao-Qin

    2013-10-01

    Mesoporous solid strong bases are highly promising for applications as environmentally benign catalysts in various reactions. Their preparation attracts increasing attention for the demand of sustainable chemistry. In the present study, a new strategy was designed to fabricate strong basicity on mesoporous silica by using multifunction of a carbon interlayer. A typical mesoporous silica, SBA-15, was precoated with a layer of carbon prior to the introduction of base precursor LiNO3. The carbon interlayer performs two functions by promoting the conversion of LiNO3 at low temperatures and by improving the alkali-resistant ability of siliceous host. Only a tiny amount of LiNO3 was decomposed on pristine SBA-15 at 400 C; for the samples containing >8 wt % of carbon, however, LiNO3 can be entirely converted to strongly basic sites Li2O under the same conditions. The guest-host redox reaction was proven to be the answer for the conversion of LiNO3, which breaks the tradition of thermally induced decomposition. More importantly, the residual carbon layer can prevent the siliceous frameworks from corroding by the newly formed strongly basic species, which is different from the complete destruction of mesostructure in the absence of carbon. Therefore, materials possessing both ordered mesostructure and strong basicity were successfully fabricated, which is extremely desirable for catalysis and impossible to realize by conventional methods. We also demonstrated that the resultant mesoporous basic materials are active in heterogeneous synthesis of dimethyl carbonate (DMC) and the yield of DMC can reach 32.4%, which is apparently higher than that over the catalysts without a carbon interlayer (<12.9%) despite the same lithium content. The strong basicity, in combination with the uniform mesopores, is believed to be responsible for such a high activity. PMID:24020837

  20. 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.

  1. Soft-templated synthesis of mesoporous carbon nanospheres and hollow carbon nanofibers

    NASA Astrophysics Data System (ADS)

    Cheng, Youliang; Li, Tiehu; Fang, Changqing; Zhang, Maorong; Liu, Xiaolong; Yu, Ruien; Hu, Jingbo

    2013-10-01

    Using coal tar pitch based amphiphilic carbonaceous materials (ACMs) as the precursor and amphiphilic triblock copolymer Plutonic P123 as the only soft template, carbon nanospheres with partially ordered mesopores and hollow carbon nanofibers were synthesized. The concentration of P123, cp, and the mass ratio of P123 to ACM, r, are the key parameters of controlling the shape of the as-prepared products. Mesoporous carbon nanospheres with diameter of 30-150 nm were prepared under the condition of cp = 13.3 g/L and r = 1.2. When cp = 26.7 g/L and r = 2, hollow carbon nanofibers with diameters of 50-200 nm and mesopores/macropores were obtained. Carbon nanospheres and hollow carbon fibers were amorphous materials. The mesoporous carbon nanospheres show good stability in the cyclic voltammograms and their specific capacitance at 10 mV s-1 is 172.1 F/g.

  2. 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

  3. 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.

  4. Electrochemical detection of ultratrace nitroaromatic explosives using ordered mesoporous carbon.

    PubMed

    Zang, Jianfeng; Guo, Chun Xian; Hu, Fengping; Yu, Lei; Li, Chang Ming

    2011-01-10

    A sensitive electrochemical sensor has been fabricated to detect ultratrace nitroaromatic explosives using ordered mesoporous carbon (OMC). OMC was synthesized and characterized by scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption measurements. Glassy carbon electrodes functionalized with OMC show high sensitivity of 62.7 ?A cm(-2) per ppb towards 2,4,6-trinitrotoluene (TNT). By comparison with other materials such as carbon nanotubes and ordered mesoporous silica, it is found that the high performance of OMC toward sensing TNT is attributed to its large specific surface area and fast electron transfer capability. As low as 0.2 ppb TNT, 1 ppb 2,4-dinitrotoluene and 1 ppb 1,3-dinitrobenzene can be detected on OMC based electrodes. This work renders new opportunities to detect ultratrace explosives for applications of environment protections and home securities against chemical warfare agents. PMID:21167969

  5. 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

  6. 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.

  7. Heteroatom doped mesoporous carbon/graphene nanosheets as highly efficient electrocatalysts for oxygen reduction.

    PubMed

    Xu, Peimin; Wu, Dongqing; Wan, Li; Hu, Pengfei; Liu, Ruili

    2014-05-01

    The high cost of platinum (Pt) based catalysts for oxygen reduction reaction (ORR) has restricted the widespread commercialization of fuel cells. Heteroatom (N, B, P, S or Se) doped carbon materials have been regarded as the promising metal-free catalysts for replacing Pt based catalysts owing to their high efficiencies, good stability and relative low cost. In this work, we present a cost-effective synthesis approach for heteroatom (N and S) doped mesoporous carbon/graphene (HMCG) nanosheets by using nano-casting technology with mesoporous silica/graphene nanosheets (MSG) as hard templates, and four different amino acids (alanine, serine, arginine and cystine) as heteroatom (N, S) and carbon precursors. The resulting catalysts exhibited excellent electrocatalytic activity for ORR in alkaline media. In particular, HMCGAla with alanine as precursors showed the highest electron transfer numbers and durability. These results indicated the attractive potential of HMCGs as metal-free catalysts in practical fuel cells. PMID:24594045

  8. Synthesis of highly-ordered mesoporous carbon/silica nanocomposites and derivative hierarchically mesoporous carbon from a phenyl-bridged organosiloxane

    NASA Astrophysics Data System (ADS)

    Wu, Zhiwang; Pang, Jiebin; Lu, Yunfeng

    2009-11-01

    Mesoporous carbon/silica nanocomposites and derivative hierarchically mesoporous carbon have been prepared using 1,4-bis(triethoxysilyl)benzene (BTEB) as a precursor for a carbon/silica network and Pluronic P123 (HO(CH2CH2O)20(CH2CH(CH3)O)70(CH2CH2O)20H) as a template for highly-ordered hexagonal pores. Co-assembly of BTEB and P123 and subsequent carbonization results in a mesoporous carbon/silica nanocomposite with hexagonally oriented pores. Removal of the silica component in the carbon/silica network creates a second porosity in the network and results in hierarchically mesoporous carbon. The mesostructure of these materials was characterized by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), powder X-ray diffraction (PXRD), and N2 sorption.

  9. 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.

  10. NiCo2O4 spinel/ordered mesoporous carbons as noble-metal free electrocatalysts for oxygen reduction reaction and the influence of structure of catalyst support on the electrochemical activity of NiCo2O4

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    Three ordered mesoporous carbons (OMCs) with different structures are used as catalyst supports for growth of NiCo2O4 spinel. The high surface area of OMCs provides more active sites to adsorb metal precursors. The porous structure confines the growth of NiCo2O4 and supplies more efficient transport passage for reactant molecules to access the active sites. Due to the structural characteristics of OMCs and catalytic properties of NiCo2O4, NiCo2O4/OMCs composites are highly active, cheap, and selective noble metal-free electrocatalysts for the oxygen reduction reaction (ORR) in alkaline solution. The electrochemical activity of NiCo2O4 supported on three OMCs with different structures, surface areas, pore sizes, pore volumes, and defective sites is studied. NiCo2O4/OMCs composites may be further used as efficient and inexpensive noble metal-free ORR catalysts in alkaline solution.

  11. 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.

  12. 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.

  13. 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

  14. Nitrogen-doped hollow carbon spheres with large mesoporous shells engineered from diblock copolymer micelles.

    PubMed

    Tang, Jing; Liu, Jian; Salunkhe, Rahul R; Wang, Tao; Yamauchi, Yusuke

    2016-01-11

    Nitrogen-doped hollow carbon spheres with engineered large tunable mesoporous (?20 nm) shells were successfully synthesized for the first time by using the colloidal silica and the diblock copolymer PS-b-PEO as the dual-template and dopamine as the precursor. The unique structural properties enable them to be promising materials as adsorbents, catalyst supports, electrode materials, drug delivery carriers and hosts for active substances. PMID:26528620

  15. 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.

  16. 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.

  17. 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

  18. Fabrication and characterization of mesoporous activated carbon from Lemna minor using one-step H3PO4 activation for Pb(II) removal

    NASA Astrophysics Data System (ADS)

    Huang, Yang; Li, Shunxing; Lin, Haibin; Chen, Jianhua

    2014-10-01

    A low cost and locally available material, Lemna minor, was used to fabricate activated carbon using H3PO4 activation. After H3PO4 activation, the L. minor activated carbons (LACs) possess high mesoporosity (92.2%) and a surface area of 531.9 m2/g according to Brunauer-Emmett-Teller (BET) analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometer (XPS) analyses reveal the presence of rich hydroxyl, carboxyl, amide and phosphate functional groups on the LACs surface, leading to facile Pb(II) binding to the surface through strong chemisorptive bonds or ion-exchange. The kinetic and equilibrium data were well described by pseudo-first-order model and Langmuir isotherm, with the maximum monolayer adsorption capacity (qm) 170.9 mg/g at 25 C. The intra-particle diffusion mechanism was partially responsible for the adsorption. The adsorption process was spontaneous and endothermic with negative ?G and positive ?H. The Pb(II)-loaded LACs could be easily regenerated using 0.1-M HCl and reused for seven cycles without significant adsorption capacity reduction. The maximum percentage removal rate for Pb(II) (20 mg/L) was found to be 91.8% within 30 min, at optimum conditions of pH 6.0 and 25 C. These suggested that the low-cost LACs could be used as a potential adsorbent in the treatment of lead-contaminated water.

  19. 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.

  20. 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.

  1. Bimodal mesoporous carbon synthesized from large organic precursor and amphiphilic tri-block copolymer by self assembly

    SciTech Connect

    Saha, Dipendu; Contescu, Cristian I; Gallego, Nidia C

    2012-01-01

    Owing to several disadvantages of traditional hard template based synthesis, soft-template or self-assembly was adopted to synthesize mesoporous carbon. In this work, we have introduced hexaphenol as a new and large organic precursor for the synthesis of mesoporous carbon by self-assembly with pluronic P123 as structure dictating agent. The resultant mesoporous carbon is bimodal in nature with median pore widths of 29 and 45 and BET surface area of 312 m2/g. Unlike previously synthesized mesoporous carbon, this carbon possesses negligible micropore volume. This mesoporous carbon is very suitable candidate for several applications including membrane separation, chemical sensor or selective sorption of larger molecules.

  2. 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

  3. Controlled synthesis of mesoporous carbon modified by tungsten carbides as an improved electrocatalyst support for the oxygen reduction reaction

    SciTech Connect

    Dai, Sheng; Wang, Xiqing; Zhou, Shenghu; Zhu, Qing

    2009-01-01

    Mesoporous carbon was modified with tungsten carbides by the carbothermal hydrogen reduction of a layer of chemisorbed 1:12 phosphotungstic anions (PW{sub 12}O{sub 40}{sup 3-}) on carbon surfaces. Depending on the temperature of carbothermal treatment, different tungsten species, i.e., W, W{sub 2}C, WC, were formed on the carbon matrix. No significant changes in both surface areas and mesostructures were observed during the formation of various tungsten species on carbon surfaces under high-temperature conditions. A uniform dispersion of Pt nanoparticles (1-6 nm) can be achieved via nanoconfinement on the surfaces of both mesoporouscarbon and tungsten carbide-modified mesoporous carbon. Pt nanoparticles supported on mesoporous carbons modified with tungsten carbide (Pt/WC-C) exhibit enhanced electrocatalytic activities relative to the control, in which mesoporous carbons without carbide modification were directly used as a support (Pt/C). In addition, both enhanced thermal stability and good electrochemical stability were observed for the Pt/WC-C electrocatalyst.

  4. 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...

  5. One-pot synthesis of ordered mesoporous silver nanoparticle/carbon composites for catalytic reduction of 4-nitrophenol.

    PubMed

    Chi, Yue; Tu, Jinchun; Wang, Minggang; Li, Xiaotian; Zhao, Zhankui

    2014-06-01

    Ordered mesoporous silver nanoparticle/carbon composites have been produced by a "one-pot" synthesis method. They have open mesopores (4.2-5.0 nm), large specific surface areas (465-584 m(2) g(-1)) and high pore volumes (0.29-0.50 cm(3) g(-1)) and contain stable, confined but accessible Ag nanoparticles. As a result, they show high performance in catalytic reduction of 4-nitrophenol (4-NP). The mesostructure and particle size as a function of Ag content were studied and correlated with the catalytic activity. The ordered mesoporous carbon framework and highly dispersed Ag nanoparticles make the material a novel system for effective contacting with the reactants and catalysis of the reaction. PMID:24703668

  6. 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 coreshell 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

  7. 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

  8. Optimization of mesoporous carbons for efficient adsorption of berberine hydrochloride from aqueous solutions.

    PubMed

    Li, Yin; Fu, Jie; Deng, Shuguang; Lu, Xiuyang

    2014-06-15

    Sixteen mesoporous carbon adsorbents were synthesized by varying the ratio of soft to hard templates in order to optimize the pore textural properties of these adsorbents. The mesoporous carbon adsorbents have a high BET specific surface area (1590.3-2193.5 m(2)/g), large pore volume (1.72-2.56 cm(3)/g), and uniform pore size distribution with a median pore diameter ranging from 3.51 nm to 4.52 nm. It was observed that pore textural properties of the carbon adsorbents critically depend on the molar ratio of carbon sources to templates, and the hard template plays a more important role than the soft template in manipulating the pore textures. Adsorption isotherms of berberine hydrochloride at 303 K were measured to evaluate the adsorption efficacy of these adsorbents. The adsorption of berberine hydrochloride from aqueous solutions on the sixteen mesoporous carbon adsorbents synthesized in this work is very efficient, and the adsorption equilibrium capacities on all samples are more than double the adsorption capacities of berberine hydrochloride of the benchmark adsorbents (polymer resins and spherical activated carbons) at similar conditions. It was observed from the adsorption experiments that the equilibrium adsorption amounts of berberine hydrochloride are strongly correlated with the BET specific surface area and pore volume of the adsorbents. The adsorbent with the highest BET of 2193.5 m(2)/g displayed the largest adsorption capacity of 574 mg/g at an equilibrium concentration of 0.10mg/mL of berberine hydrochloride in an aqueous solution. PMID:24767505

  9. 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).

  10. 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

  11. 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

  12. 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

  13. 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.

  14. Enhanced capacitive deionization of graphene/mesoporous carbon composites.

    PubMed

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

    2012-09-01

    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 ?g g? for the GE/MC composite electrode with a GE content of 5 wt%, which is much higher than that of MC alone (590 ?g g?). The enhanced CDI performance of the composite electrodes can be attributed to the better conductive behaviour and higher specific surface area. PMID:22836788

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

    PubMed

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

    2012-07-01

    A supercapacitor has the advantages of both the conventional capacitors and the rechargeable batteries. Mn oxide is generally recognized one of the potential materials that can be used for a supercapacitor, but its low conductivity is a limiting factor for electrode materials. In this study, a hybrid of amorphous Mn oxide (AMO) and ordered mesoporous carbon (OMC) was prepared and characterized using X-ray diffraction, transmission electron microscopy, N2/77 K sorption techniques, and electrochemical analyses. The findings indicate that the electrochemical activities of Mn oxide were facilitated when it was in the hybrid state because OMC acted as a pathway for both the electrolyte ions and the electrons due to the characteristics of the ordered mesoporous structure. The ordered mesoporous structure of OMC was well maintained even after hybridization with amorphous Mn oxide. The electrochemical-activity tests revealed that the AMO/OMC hybrid had a higher specific capacitance and conductivity than pure Mn oxide. In the case where the Mn/C weight ratio was 0.75, the composite showed a high capacitance of 153 F/g, which was much higher than that for pure Mn oxide, due to the structural effects of OMC. PMID:22966638

  16. 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.

  17. Controllable synthesis of mesoporous carbon nanospheres and Fe-N/carbon nanospheres as efficient oxygen reduction electrocatalysts

    NASA Astrophysics Data System (ADS)

    Wei, Jing; Liang, Yan; Zhang, Xinyi; Simon, George P.; Zhao, Dongyuan; Zhang, Jin; Jiang, Sanping; Wang, Huanting

    2015-03-01

    The synthesis of mesoporous carbon nanospheres (MCNs), especially with diameters below 200 nm remains a great challenge due to weak interactions between the carbon precursors and soft templates, as well as the uncontrollable cross-linking rate of carbon precursors. Herein, we demonstrate a simple acid-assisted, hydrothermal synthesis approach to synthesizing such uniform MCNs with well controlled diameters ranging from 20 to 150 nm under highly acidic conditions (2 M HCl). Both the carbon precursor and the template are partly protonated under such conditions and show additional Coulombic interactions with chloride ions (acts as mediators). This kind of enhanced interaction is similar to that of the ``I+X-S+'' mechanism in the synthesis of mesoporous metal oxide, which can effectively retard the cross-linking rate of resol molecules and avoid macroscopic phase separation during the hydrothermal synthesis. Due to their uniform spherical morphology, small diameter, and high surface areas, MCNs can be modified with Fe and N species via impregnation of cheap precursors (ferric nitrate and dicyandiamide), which are further converted into nonprecious electrocatalysts for oxygen reduction reactions. The resulting Fe-N/MCNs exhibit high catalytic activities, long-term stability and improved methanol tolerance under alkaline conditions, which can be potentially used in direct methanol fuel cells and metal-air batteries.The synthesis of mesoporous carbon nanospheres (MCNs), especially with diameters below 200 nm remains a great challenge due to weak interactions between the carbon precursors and soft templates, as well as the uncontrollable cross-linking rate of carbon precursors. Herein, we demonstrate a simple acid-assisted, hydrothermal synthesis approach to synthesizing such uniform MCNs with well controlled diameters ranging from 20 to 150 nm under highly acidic conditions (2 M HCl). Both the carbon precursor and the template are partly protonated under such conditions and show additional Coulombic interactions with chloride ions (acts as mediators). This kind of enhanced interaction is similar to that of the ``I+X-S+'' mechanism in the synthesis of mesoporous metal oxide, which can effectively retard the cross-linking rate of resol molecules and avoid macroscopic phase separation during the hydrothermal synthesis. Due to their uniform spherical morphology, small diameter, and high surface areas, MCNs can be modified with Fe and N species via impregnation of cheap precursors (ferric nitrate and dicyandiamide), which are further converted into nonprecious electrocatalysts for oxygen reduction reactions. The resulting Fe-N/MCNs exhibit high catalytic activities, long-term stability and improved methanol tolerance under alkaline conditions, which can be potentially used in direct methanol fuel cells and metal-air batteries. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00331h

  18. 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

  19. Soft-templated Mesoporous Carbon-Carbon Nanotube Composites for High Performance Lithium-ion Batteries

    SciTech Connect

    Guo, Bingkun; Wang, Xiqing; Fulvio, Pasquale F; Chi, Miaofang; Mahurin, Shannon Mark; Sun, Xiao-Guang; Dai, Sheng

    2011-01-01

    Mesoporous carbon with homogeneously dispersed multi-walled carbon nanotubes (MWNTs) are synthesized via a one-step brick and mortar soft-templating approach. Nanocomposites exhibit high rate capability and reversible lithium storage capacity of 900 mA h g-1 and good rate performance. Such homogeneous nanocomposites are ideal candidates for electric vehicle applications where high power and energy density are primary requirements.

  20. 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

  1. 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).

  2. 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

  3. Nitrogen-Doped Mesoporous Carbon for Carbon Capture A Molecular Simulation Study

    SciTech Connect

    Babarao, Ravichandar; Dai, Sheng; Jiang, Deen

    2012-01-01

    Using molecular simulation, we investigate the effect of nitrogen doping on adsorption capacity and selectivity of CO{sub 2} versus N{sub 2} in model mesoporous carbon. We show that nitrogen doping greatly enhances CO{sub 2} adsorption capacity; with a 7 wt % dopant concentration, the adsorption capacity at 1 bar and 298 K increases from 3 to 12 mmol/g (or 48% uptake by weight). This great enhancement is due to the preferred interaction between CO{sub 2} and the electronegative nitrogen. The nitrogen doping coupled with the mesoporosity also leads to a much higher working capacity for adsorption of the CO{sub 2}/N{sub 2} mixture in nitrogen-doped mesoporous carbon. In addition, the CO{sub 2}/N{sub 2} selectivity is almost 5 times greater than in nondoped carbon at ambient conditions. This work indicates that nitrogen doping is a promising strategy to create mesoporous carbons for high-capacity, selective carbon capture.

  4. 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.

  5. 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.

  6. 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

  7. Neutron imaging of ion transport in mesoporous carbon materials.

    PubMed

    Sharma, Ketki; Bilheux, Hassina Z; Walker, Lakeisha M H; Voisin, Sophie; Mayes, Richard T; Kiggans, Jim O; Yiacoumi, Sotira; DePaoli, David W; Dai, Sheng; Tsouris, Costas

    2013-07-28

    Neutron imaging is presented as a tool for quantifying the diffusion of ions inside porous materials, such as carbon electrodes used in the desalination process via capacitive deionization and in electrochemical energy-storage devices. Monolithic mesoporous carbon electrodes of ?10 nm pore size were synthesized based on a soft-template method. The electrodes were used with an aqueous solution of gadolinium nitrate in an electrochemical flow-through cell designed for neutron imaging studies. Sequences of neutron images were obtained under various conditions of applied potential between the electrodes. The images revealed information on the direction and magnitude of ion transport within the electrodes. From the time-dependent concentration profiles inside the electrodes, the average value of the effective diffusion coefficient for gadolinium ions was estimated to be 2.09 0.17 10(-11) m(2) s(-1) at 0 V and 1.42 0.06 10(-10) m(2) s(-1) at 1.2 V. The values of the effective diffusion coefficient obtained from neutron imaging experiments can be used to evaluate model predictions of the ion transport rate in capacitive deionization and electrochemical energy-storage devices. PMID:23756558

  8. 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.

  9. 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

  10. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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 m2 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.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 m2 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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03802b

  12. Synthesis, characterization and dye removal capacities of N-doped mesoporous carbons.

    PubMed

    Snchez-Snchez, ; Surez-Garca, F; Martnez-Alonso, A; Tascn, J M D

    2015-07-15

    Nitrogen-doped ordered mesoporous carbons were synthesized by chemical vapor deposition, using acetonitrile as carbon and nitrogen source and SBA-15 as mesoporous silica template. Their porous texture, structural order and surface chemistry were studied as a function of the experimental conditions (acetonitrile stream concentration and deposition time). A non-doped ordered mesoporous carbon was also prepared by the same procedure using propylene as carbon source. Methylene blue, methyl orange and fuchsin acid were selected as probe molecules to investigate the dye adsorption behavior on the ordered mesoporous carbons. Both N-doped and non-doped ordered mesoporous carbons adsorbed large amounts of these three dyes demonstrating the importance of mesoporosity, especially for the adsorption of larger dyes (e.g. fuchsin acid). The presence of nitrogen functional groups was detrimental for the adsorption of the basic dye (methylene blue). On the other hand, the nitrogen functionalities improved the adsorption kinetics for both acid and basic dyes, and the N-doped samples achieved 100% of their maximum adsorption capacities in less than 15 min. PMID:25801137

  13. Enhancement of thermal reversibility and stability of human carbonic anhydrase II by mesoporous nanoparticles.

    PubMed

    Khatibi, Ali; Ma'mani, Leila; Khodarahmi, Reza; Shafiee, Abbas; Maghami, Parvaneh; Ahmad, Faizan; Sheibani, Nader; Moosavi-Movahedi, Ali Akbar

    2015-04-01

    Aminopropyl functionalized PEGylated mesoporous silica nanoparticles [H2N-Pr@PEGylated SBA-15] were synthesized and evaluated as a promising biocompatible additive to study the activity and thermal reversibility and stability of human carbonic anhydrase II (HCA II). For this purpose, the additive was prepared by covalent amino propyl functionalization of mesoporous silica nanoparticles (MSNs) bearing PEG moiety as linker. The MSNs was fully characterized using different techniques including transmission electron microscopy, N2 adsorption-desorption measurements, thermal gravimetric analysis, Fourier transform infrared spectroscopy and dynamic light scattering. The average particle size of [H2N-Pr@PEGylated SBA-15] was about 80 nm and showed high loading capacity for HCA II at pH 7.75 as a target protein. The efficiency of [H2N-Pr@PEGylated SBA-15] in improving reversibility of HCA II was investigated by various techniques including UV-vis, 1,8-Anilinonaphtalene Sulfonate (ANS) fluorescence, circular dichroism (CD), and differential scanning calorimetry. Our results showed that [H2N-Pr@PEGylated SBA-15] can increase the protein thermal reversibility and stability. Herein, kinetic studies were applied to confirm the ability of [H2N-Pr@PEGylated SBA-15] in increasing the activity of HCA II at high temperatures. Together our results present the [H2N-Pr@PEGylated SBA-15] as a water-dispersible and efficient additive for improving the activity, and thermal reversibility and stability of enzyme. PMID:25600988

  14. Iron Carbide Nanoparticles Encapsulated in Mesoporous Fe-N-Doped Carbon Nanofibers for Efficient Electrocatalysis.

    PubMed

    Wu, Zhen-Yu; Xu, Xing-Xing; Hu, Bi-Cheng; Liang, Hai-Wei; Lin, Yue; Chen, Li-Feng; Yu, Shu-Hong

    2015-07-01

    Exploring low-cost and high-performance nonprecious metal catalysts (NPMCs) for oxygen reduction reaction (ORR) in fuel cells and metal-air batteries is crucial for the commercialization of these energy conversion and storage devices. Here we report a novel NPMC consisting of Fe3 C nanoparticles encapsulated in mesoporous Fe-N-doped carbon nanofibers, which is synthesized by a cost-effective method using carbonaceous nanofibers, pyrrole, and FeCl3 as precursors. The electrocatalyst exhibits outstanding ORR activity (onset potential of -0.02?V and half-wave potential of -0.140?V) closely comparable to the state-of-the-art Pt/C catalyst in alkaline media, and good ORR activity in acidic media, which is among the highest reported activities of NPMCs. PMID:26014581

  15. Oxidative Dehydrogenation of Isobutane on Phosphorous-Modified Graphitic Mesoporous Carbon

    SciTech Connect

    Schwartz, Viviane; Xie, Hong; Meyer III, Harry M; Overbury, Steven {Steve} H; Liang, Chengdu

    2011-01-01

    Phosphorous heteroatoms were added in order to tune the selectivity and investigate the roles of different oxygen species in graphitic mesoporous carbons for the oxidative dehydrogenation reaction of isobutane to isobutene. Small changes in the apparent isobutane activation energy are consistent with the notion that the phosphorous groups do not change the nature of the active sites but they interfere with the availability of the sites. Our results show that the improvement on selectivity is not proportional to the amount of phosphorous added. Small phosphorous content improved the selectivity by suppressing the combustion of isobutane. However, a higher amount of phosphorous groups lead to coverage of selective quinone sites and/or creation of active sites favorable to total oxidation.

  16. Self-Assembly Synthesis and Functionalization of Mesoporous Carbon Materials for Energy-Related Applications

    SciTech Connect

    Dai, Sheng

    2009-01-01

    Self-Assembly Synthesis and Functionalization of Mesoporous Carbon Materials for Energy-Related Applications Sheng Dai Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6201 Porous carbon materials are ubiquitous in separation, catalysis, and energy storage/conversion. Well-defined mesoporous carbon materials are essential for a number of the aforementioned applications. Ordered porous carbon materials have previously been synthesized using colloidal crystals and presynthesized mesoporous silicas as hard templates. The mesostructures of these carbon materials are connected via ultrathin carbon filaments and can readily collapse under high-temperature conditions. Furthermore, these hard-template methodologies are extremely difficult to adapt to the fabrication of large-scale ordered nanoporous films or monoliths with controlled pore orientations. More recently, my research group at the Oak Ridge National Laboratory and several others around the world have developed alternative methods for synthesis of highly ordered mesoporous carbons via self-assembly. Unlike the mesoporous carbons synthesized via hard-template methods, these mesoporous carbons are highly stable and can be graphitized at high temperature (>2800?C) without significant loss of mesopores. The surface properties of these materials can be further tailored via surface functionalization. This seminar will provide an overview and perspective of the mesoporous carbon materials derived from soft-template synthesis and surface functionalization and their fascinating applications in catalysis, separation, and energy storage devices. Dr. Sheng Dai got his B.S. and M.S. degrees from Zhejiang University in 1984 and 1986, respectively. He subsequently obtained a PhD degree from the University of Tennessee, Knoxville in 1990. He is currently a Senior Staff Scientist and Group Leader of Nanomaterials Group and Center for Nanophase Materials Science of Oak Ridge National Laboratory and is also affiliated with the University of Tennessee as an adjunct professor. He is a co-author of more than 200 publications. His research interests include porous materials and their functionalization, new ionic liquids for chemical separation and materials synthesis, sol-gel synthesis and molecular imprinting of inorganic materials, and catalysis by nanomaterials especially gold nanocatalysts.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. "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

  3. Soft-template-carbonization route to highly textured mesoporous carbon-TiO? 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

  4. 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.

  5. 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.

  6. 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

  7. Electrical stimuli to increase cell proliferation on carbon nanotubes/mesoporous silica composites for drug delivery.

    PubMed

    Vila, M; Cicundez, M; Snchez-Marcos, J; Fal-Miyar, V; Manzano, M; Prieto, C; Vallet-Regi, M

    2013-01-01

    The development of smart materials as bone implants is nowadays a challenging task to optimize their fast osteointegration. Nevertheless, no attempts have been done in joining the possibility of using electrical stimulation and drug delivery together in a material intended for bone tissue engineering. Moreover, the use of this synergy to induce bone healing is still limited until novel drug reservoirs material formulations allow an efficient applicability of the electrical stimuli. Herein, we present the biological response of osteoblasts cells, cultured over carbon nanotubes-mesoporous silica composites while exposed to external electrical stimulus. Moreover, its ability to function as drug delivery systems is also demonstrated. Bone cell metabolism was stimulated and mitochondrial activity was increased up to seven times in the presence of these composites under electrical stimulus, suggesting their potential application in bone regeneration processes. PMID:22847920

  8. 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.

  9. 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.

  10. 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.

  11. Mesoporous carbon amperometric glucose sensors using inexpensive, commercial methacrylate-based binders.

    PubMed

    Dai, Mingzhi; Maxwell, Stephanie; Vogt, Bryan D; La Belle, Jeffrey T

    2012-08-13

    Two ordered, soft-templated mesoporous carbon powders with cubic and hexagonal framework structure and four different commercial, low cost methacrylate-based polymer binders with widely varying physical properties are investigated as screen printed electrodes for glucose sensors using glucose oxidase and ferricyanide as the mediator. Both the chemistry and concentration of the binder in the electrode formulation can significantly impact the performance. Poly(hydroxybutyl methacrylate) as the binder provides hydrophilicity to enable transport of species in the aqueous phase to the carbon surface, but yet is sufficiently hydrophobic to provide mechanical robustness to the sensor. The current from the mesoporous carbon electrodes can be more than an order of magnitude greater than for a commercial printed carbon electrode (Zensor) with improved sensitivity for model glucose solutions. Even when applying these sensors to rabbit whole blood, the performance of these glucose sensors compares favorably to a standard commercial glucose meter with the lower detection limit of the mesoporous electrode being approximately 20mgdL(-1) despite the lack of a separation membrane to prevent non-specific events; these results suggest that the small pore sizes and high surface areas associated with ordered mesoporous carbons may effectively decrease some non-specific inferences for electrochemical sensing. PMID:22790696

  12. 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.

  13. 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.

  14. Bicontinuous mesoporous carbon thin films via an order-order transition.

    PubMed

    Deng, Guodong; Zhang, Yuanzhong; Ye, Changhuai; Qiang, Zhe; Stein, Gila E; Cavicchi, Kevin A; Vogt, Bryan D

    2014-10-28

    Bicontinuous mesoporous carbon films are fabricated by cooperative self-assembly of phenolic resin and amphiphilic triblock copolymer via an order-order transition from cylinders to gyroid. The film morphology is strongly influenced by the details of processing, including age of the resol, resol?:?template ratio, and the solvent vapor annealing process. PMID:25207485

  15. 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

  16. 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.

  17. 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.

  18. 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

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

    SciTech Connect

    Peter Zalupski; Rocklan McDowell; Guy Dutech

    2014-10-01

    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.

  20. 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

  1. 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.

  2. 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

  3. 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 Cdfatty 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.

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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

  11. 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.

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

    PubMed

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

    2015-08-28

    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/cm(3) and 0.5 g/cm(3), 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. PMID:26328861

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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

  18. Bifunctional metal-free catalysis of mesoporous noble carbons for oxygen reduction and evolution reactions.

    PubMed

    Sakaushi, Ken; Fellinger, Tim-Patrick; Antonietti, Markus

    2015-04-13

    Electrochemical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key reactions in lithium-oxygen batteries (LOBs) being a promising candidate to store renewable energies due to their high specific energy. However current development on LOBs is suffering from unsuitable catalysts. In particular, carbon-based catalysts were found to perform poorly in this system. Here, we show that metal-free mesoporous nitrogen-doped carbons (meso-NdCs) offer highly promising performances in both ORR and OER; they act as bifunctional catalysts, and can be synthesized by a very simple method. The efficient electrocatalytic activity of ORR and OER was used in a LOB cell during discharge and charge, respectively, and the present system showed a lower overpotential comparable to metal-based catalysts in LOB system. Thus, we demonstrate that meso-NdCs act as a new and affordable candidate for the efficient bifunctional oxygen catalysis, therefore can be applied to many energy-related applications. PMID:25739370

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. Surface Engineering of Polypropylene Membranes with Carbonic Anhydrase-Loaded Mesoporous Silica Nanoparticles for Improved Carbon Dioxide Hydration.

    PubMed

    Yong, Joel K J; Cui, Jiwei; Cho, Kwun Lun; Stevens, Geoff W; Caruso, Frank; Kentish, Sandra E

    2015-06-01

    Carbonic anhydrase (CA) is a native enzyme that facilitates the hydration of carbon dioxide into bicarbonate ions. This study reports the fabrication of thin films of active CA enzyme onto a porous membrane substrate using layer-by-layer (LbL) assembly. Deposition of multilayer films consisting of polyelectrolytes and CA was monitored by quartz crystal microgravimetry, while the enzymatic activity was assayed according to the rates of p-nitrophenylacetate (p-NPA) hydrolysis and CO2 hydration. The fabrication of the films onto a nonporous glass substrate showed CO2 hydration rates of 0.52 0.09 ?mol cm(-2) min(-1) per layer of bovine CA and 2.6 0.7 ?mol cm(-2) min(-1) per layer of a thermostable microbial CA. The fabrication of a multilayer film containing the microbial CA on a porous polypropylene membrane increased the hydration rate to 5.3 0.8 ?mol cm(-2) min(-1) per layer of microbial CA. The addition of mesoporous silica nanoparticles as a film layer prior to enzyme adsorption was found to increase the activity on the polypropylene membranes even further to a rate of 19 4 ?mol cm(-2) min(-1) per layer of microbial CA. The LbL treatment of these membranes increased the mass transfer resistance of the membrane but decreased the likelihood of membrane pore wetting. These results have potential application in the absorption of carbon dioxide from combustion flue gases into aqueous solvents using gas-liquid membrane contactors. PMID:25984966

  14. 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

  15. 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 ? = 0 and ? = 90 is included along with 2D GISAXS data for all azimuthal data associated with FDU-15-P123 to illustrate th

  16. A co-confined carbonization approach to aligned nitrogen-doped mesoporous carbon nanofibers and its application as an adsorbent.

    PubMed

    Chen, Aibing; Liu, Chao; Yu, Yifeng; Hu, Yongqi; Lv, Haijun; Zhang, Yue; Shen, Shufeng; Zhang, Jian

    2014-07-15

    Nitrogen-doped carbon nanofibers (MCNFs) with an aligned mesoporous structure were synthesized by a co-confined carbonization method using anodic aluminum oxide (AAO) membrane and tetraethylorthosilicate (TEOS) as co-confined templates and ionic liquids as the precursor. The as-synthesized MCNFs with the diameter of 80-120nm possessed a bulk nitrogen content of 5.3wt% and bimodal mesoporous structure. The nitrogen atoms were mostly bound to the graphitic network in two forms, i.e. pyridinic and pyrrolic nitrogen, providing adsorption sites for acidic gases like SO2 and CO2. Cyclic experiments revealed a considerable stability of MCNFs over 20 runs of SO2 adsorption and 15 runs for CO2 adsorption. The MCNFs also have a preferable adsorption performance for Cd(2+). PMID:24887121

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

    PubMed

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

    2015-12-01

    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. PMID:26526104

  18. Heterogeneous Fenton-like degradation of 4-chlorophenol using iron/ordered mesoporous carbon catalyst.

    PubMed

    Duan, Feng; Yang, Yuezhu; Li, Yuping; Cao, Hongbin; Wang, Yi; Zhang, Yi

    2014-05-01

    Ordered mesoporous carbon supported iron catalysts (Fe/OMC) were prepared by the incipient wetness impregnation method and investigated in Fenton-like degradation of 4-chlorophenol (4CP) in this work. XRD and TEM characterization showed that the iron oxides were well dispersed on the OMC support and grew bigger with the increasing calcination temperature. The catalyst prepared with a lower calcination temperature showed higher decomposition efficiency towards 4CP and H2O2, but more metals were leached. The effect of different operational parameters such as initial pH, H2O2 dosage, and reaction temperature on the catalytic activity was evaluated. The results showed that 96.1% of 4CP and 47.4% of TOC was removed after 270 min at 30C, initial pH of 3 and 6.6 mmol/L H2O2. 88% of 4CP removal efficiency was retained after three successive runs, indicating Fe/OMC a stable catalyst for Fenton reaction. 4CP was degraded predominately by the attack of hydroxyl radical formed on the catalyst surface and in the bulk solution due to iron leaching. Based on the degradation intermediates detected by high performance liquid chromatography, possible oxidation pathways were proposed during the 4CP degradation. PMID:25079648

  19. General synthesis of discrete mesoporous carbon microspheres through a confined self-assembly process in inverse opals.

    PubMed

    Sun, Zhenkun; Liu, Yong; Li, Bin; Wei, Jing; Wang, Minghong; Yue, Qin; Deng, Yonghui; Kaliaguine, Serge; Zhao, Dongyuan

    2013-10-22

    A general confined coassembly process has been demonstrated to produce discrete uniform mesoporous carbon microspheres with 0.8-1 ?m particle size using 3-D-ordered macroporous silica as the template. The obtained mesoporous carbon microspheres (MC-MSs) have uniform and discrete spherical morphology, variable symmetry (hexagonal p6mm or cubic Im3m) of mesostructures, high specific surface areas (500-1100 m(2)/g), large pore volumes (0.6-2.0 cm(3)/g), and highly accessible large mesopores (7-10.3 nm). The particle size of the carbon microspheres can be easily tuned by simply using templates with different macropore sizes. It was found that the smaller MC-MSs (330 nm) with higher surface-to-volume ratio tend to shape into an integral monolithic MC-MS matrix and larger MC-MSs (>800 nm) with lower surface-to-volume ratio to discrete spherical morphology. This feature is attributed to the difference in shrinkage behavior of mesoporous carbon spheres confined in the macropores caused by the interaction between the silica wall and carbon microspheres. Adsorption experiments indicate that the cobalt-based nanoparticle-incorporated mesoporous carbon microspheres exhibit excellent size selectivity for protein adsorption in a complex solution and good magnetic separability for easy recycling. PMID:24044674

  20. 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

  1. Palladium nanoparticles decorated mesoporous carbon spheres as catalyst for reduction of 4-nitrophenol.

    PubMed

    Huang, Xin Hua; Moon, Byeong Kyu; Byeon, Seong Jin; Heo, Min Seon; Kim, Ii

    2014-11-01

    Two kinds of polyaromatics with mesoporous have been synthesized from aromatic hydrocarbons using anhydrous zinc chloride as the Friedel-Crafts catalyst and chloromethyl methyl ether as a cross-linker, after the Pd nanoparticles (PdNPs) decorated on the mesoporous carbon spheres (Pd@CSs) have been prepared by simply mixing the as-prepared polyaromatics (polynaphthalene or polypyrene) with PdCl2, reducing the Pd2+ to Pd0 by using NaBH4, followed by thermal treatment at 600 degrees C for 5 h in nitrogen atmosphere. The synthesized PdNPs have a uniform size distribution with an average size smaller than 15 nm and they can be loaded on the highly mesoporous carbon microspheres. Structural of the resulting Pd@CSs were carried out using FE-SEM, HR-TEM, X-ray differaction, dispersive X-ray spectroscopy. The resulting Pd@CSs have been investigated as a catalyst for the reduction of 4-nitrophenol to 4-aminophenol, showing the Pd@CSs have high catalytic reactivity and recyclability. PMID:25958601

  2. Bifunctionalized mesoporous silica-supported gold nanoparticles: intrinsic oxidase and peroxidase catalytic activities for antibacterial applications.

    PubMed

    Tao, Yu; Ju, Enguo; Ren, Jinsong; Qu, Xiaogang

    2015-02-11

    Bifunctionalized mesoporous silica-supported gold nanoparticles as oxidase and peroxidase mimics for antibacterial applications are demonstrated. For the first time, these mesoporous silica-supported gold nanoparticles are applied as oxidase and peroxidase mimics. Taking advantage of their prominent enzyme activities, the MSN-AuNPs show excellent antibacterial properties against both Gram-negative and Gram-positive bacteria. Furthermore, MSN-AuNPs also exhibit outstanding performance in biofilm elimination . PMID:25655182

  3. 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.

  4. 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

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

    SciTech Connect

    Fulvio, Pasquale F; Veith, Gabriel M; Adcock, Professor Jamie L.; Brown, Suree; Mayes, Richard T; Wang, Xiqing; Mahurin, Shannon Mark; Guo, Bingkun; Puretzky, Alexander A; Rouleau, Christopher; Geohegan, David B; Dai, Sheng

    2013-01-01

    Ordered mesoporous carbon graphitic carbon composites prepared by the brick and mortar method were fluorinated using F2 and investigated as cathodes for primary lithium batteries. The resulting materials have a rich array of C F species, asmeasured by XPS, which influence conduction and voltage profiles.

  6. 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 ?-? 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

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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

  12. Mesoporous carbon-vanadium oxide films by resol-assisted, triblock copolymer-templated cooperative self-assembly.

    PubMed

    Bhaway, Sarang M; Kisslinger, Kim; Zhang, Lihua; Yager, Kevin G; Schmitt, Andrew L; Mahanthappa, Mahesh K; Karim, Alamgir; Vogt, Bryan D

    2014-11-12

    Unlike other crystalline metal oxides amenable to templating by the combined assemblies of soft and hard chemistries (CASH) method, vanadium oxide nanostructures templated by poly(ethylene oxide-b-1,4-butadiene-b-ethylene oxide) (OBO) triblock copolymers are not preserved upon high temperature calcination in argon. Triconstituent cooperative assembly of a phenolic resin oligomer (resol) and an OBO triblock in a VOCl3 precursor solution enhances the carbon yield and can prevent breakout crystallization of the vanadia during calcination. However, the calcination environment significantly influences the observed mesoporous morphology in these composite thin films. Use of an argon atmosphere in this processing protocol leads to nearly complete loss of carbon-vanadium oxide thin film mesostructure, due to carbothermal reduction of vanadium oxide. This reduction mechanism also explains why the CASH method is not more generally successful for the fabrication of ordered mesoporous vanadia. Carbonization under a nitrogen atmosphere at temperatures up to 800 C instead enables formation of a block copolymer-templated mesoporous structure, which apparently stems from the formation of a minor fraction of a stabilizing vanadium oxynitride. Thus, judicious selection of the inert gas for template removal is critical for the synthesis of well-defined, mesoporous vanadia-carbon composite films. This resol-assisted assembly method may generally apply to the fabrication of other mesoporous materials, wherein inorganic framework crystallization is problematic due to kinetically competitive carbothermal reduction processes. PMID:25317954

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

    PubMed

    de Poulpiquet, Anne; Marques-Knopf, Helena; Wernert, Vronique; Giudici-Orticoni, Marie Thrse; 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

  14. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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.

  16. 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.

  17. 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.

  18. A simple synthesis method for nano-metal catalyst supported on mesoporous carbon: the solution plasma process.

    PubMed

    Kang, Jun; Li, Oi Lun; Saito, Nagahiro

    2013-08-01

    High-electrocatalytic-activity noble nanoparticles (NPs) supported on carbon nanoballs (CNBs) were synthesized using an innovative plasma-in-liquid method, which is known as solution plasma processing (SPP). This technique uses a one-step method for the synthesis of NPs on carbon materials. CNBs are formed using benzene as a carbon precursor while gold (Au) or platinum (Pt) nanoparticles are generated instantaneously via sputtering from metal electrodes. The synthesized NP/CNBs were annealed at 850 C in order to increase the conductivity of the material. The results of structural characterizations reveal that the Au and Pt NPs are smaller than 10 nm and have a uniform size distribution, and these NPs are successfully loaded onto highly mesoporous CNBs that have an average pore diameter between 13 and 16 nm. In the results from cyclic voltammetry measurements, the Au/CNBs and Pt/CNBs show clear peaks corresponding to the oxidation and reduction features in the catalytic reactions. Apart from noble nanoparticles, SPP can also be used to synthesize various kinds of NPs including bimetallic NPs loaded on spherical carbon supports by changing the working electrodes. The proposed mechanism for the synthesis is discussed in detail. This method shows potential to be a candidate for the next-generation synthesis of NP/carbon in the future. PMID:23783397

  19. 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).

  20. Metal free nitrogen doped hollow mesoporous graphene-analogous spheres as effective electrocatalyst for oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Yan, Jing; Meng, Hui; Xie, Fangyan; Yuan, Xiaoli; Yu, Wendan; Lin, Worong; Ouyang, Wenpeng; Yuan, Dingsheng

    2014-01-01

    Nitrogen-doped hollow mesoporous carbon spheres has been synthesized from mesoporous silica spheres using glycine as carbon and nitrogen precursor. The wall of the spheres is composed by broken graphene. The metal free nitrogen-doped hollow mesoporous carbon spheres are proven to be active electrocatalyst for the oxygen reduction reaction in alkaline solution. A unique advantage of the nitrogen-doped hollow mesoporous carbon sphere is its methanol-tolerant property because of the absence of active metal. The catalytic activity is ascribed to the pyridinic-nitrogen formed during pyrolysis and the graphene-like structure. To the best of our knowledge this is the first report on the nitrogen-doped hollow mesoporous carbon sphere as a metal-free electrocatalyst for the oxygen reduction reaction which is an important reaction in fuel cell. The prepared mesoporous carbon material can also be used as catalyst support and find application both in the anode and cathode of fuel cell.

  1. 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.

  2. 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}.

  3. 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.

  4. 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

  5. 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; Mllen, 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

  6. 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.

  7. 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

  8. Silica nanonetwork confined in nitrogen-doped ordered mesoporous carbon framework for high-performance lithium-ion battery anodes.

    PubMed

    Liang, Yeru; Cai, Lifeng; Chen, Luyi; Lin, Xidong; Fu, Ruowen; Zhang, Mingqiu; Wu, Dingcai

    2015-03-01

    A new class of nitrogen-doped ordered mesoporous carbon/silica (N-OMC/SiO2) nanocomposites was successfully fabricated via a multi-constituent co-assembly strategy. The N-OMC/SiO2 nanocomposite presented a unique interpenetrating carbon/silica structure whose carbon/silica interface is highly uniform, and thus demonstrated high capacity, good cycling and excellent rate properties. PMID:25673004

  9. 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

  10. Transport of ions in mesoporous carbon electrodes during capacitive deionization of high-salinity solutions.

    PubMed

    Sharma, K; Kim, Y-H; Gabitto, J; Mayes, R T; Yiacoumi, S; Bilheux, H Z; Walker, L M H; Dai, S; Tsouris, C

    2015-01-27

    Desalination of high-salinity solutions has been studied using a novel experimental technique and a theoretical model. Neutron imaging has been employed to visualize lithium ions in mesoporous carbon materials, which are used as electrodes in capacitive deionization (CDI) for water desalination. Experiments were conducted with a flow-through CDI cell designed for neutron imaging and with lithium-6 chloride ((6)LiCl) as the electrolyte. Sequences of neutron images have been obtained at a relatively high concentration of (6)LiCl solution to provide information on the transport of ions within the electrodes. A new model that computes the individual ionic concentration profiles inside mesoporous carbon electrodes has been used to simulate the CDI process. Modifications have also been introduced into the simulation model to calculate results at high electrolyte concentrations. Experimental data and simulation results provide insight into why CDI is not effective for desalination of high ionic-strength solutions. The combination of experimental information, obtained through neutron imaging, with the theoretical model will help in the design of CDI devices, which can improve the process for high ionic-strength solutions. PMID:25533167

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. Nanoscale gold intercalated into mesoporous silica as a highly active and robust catalyst

    NASA Astrophysics Data System (ADS)

    Wang, Xue; Chen, Lifang; Shang, Meng; Lin, Feng; Hu, Juncheng; Richards, Ryan M.

    2012-07-01

    Stable gold/mesoporous silica nanocomposites (with Au nanoparticles intercalated in the walls of mesoporous silica) were successfully synthesized by the hydrothermal method and applied as catalysts. A challenging issue associated with intercalation and the use of coordinating agents is the effect of the coordinating agent on the mesoporous silica structure and periodicity. This investigation is targeted at elaborating the effect of the coordinating agent on the resulting mesoporous structure. The amount of Au coordinating agent bis[3-(triethoxysilyl)propyl]-tetrasulfide (TESPTS) was systematically altered to synthesize a range of materials with varying Au loadings and morphologies. These materials were characterized by N2 adsorption-desorption, x-ray diffraction, transmission electron microscopy and UV-visible spectroscopy. The structures of the catalysts were found to range from mesoporous to vesical- and foam-like upon varying the TESPTS/polymer template (P123) ratio. Additionally, the sizes of Au nanoparticles increased by increasing the amount of TESPTS. The catalytic properties of the resulting materials were examined using oxidation of benzyl alcohol and reduction of 4-nitrophenol as probe reactions. The intercalated systems demonstrated high activity and more importantly were robust and readily reusable. This approach to imparting stability to nanoscale materials may be much more broadly applicable and expand the types of environments in which they can be utilized.

  19. 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.

  20. 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 660Fg-1 at current densities of 2 A g-1 in 2M KOH aqueous solution. In addition, the composite electrode shows excellent mechanical behavior and long-term cyclic stability (91.8% capacitance retention after 3,000cycles). The fabrication method presented here is facile, cost-effective, and scalable, which may open a new pathway for real device applications. PMID:24661431

  1. 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

  2. Mesoporous carbon-TiO? beads with nanotextured surfaces as photoanodes in dye-sensitized solar cells.

    PubMed

    Quan, Li Na; Jang, Yoon Hee; Jang, Yu Jin; Kim, Jihyeon; Lee, Wonmok; Moon, Jun Hyuk; Kim, Dong Ha

    2014-09-01

    Mesoporous TiO2 and carbon-TiO2 beads with highly roughened surfaces at the nanoscale were prepared by using triblock copolymer P123 simultaneously as template and carbon source in combination with colloid self-assembly. In addition, their role as modifier of the photoanode in the efficiency enhancement of dye-sensitized solar cells is discussed. Hierarchically organized TiO2 networks can provide fast electron transport paths, and ordered mesopores can enhance light scattering as well as facilitate infiltration of the electrolyte. It was found that there is an optimum loading level of mesoporous TiO2 and carbon-TiO2 beads, that is, 1.0 and 0.5?wt%, with respect to the control P25 TiO2 nanoparticles, respectively, for maximizing the photovoltaic performance. An increase in the photovoltaic performance by up to 21.45% was achieved by incorporation of mesoporous carbon-TiO2 beads into the conventional photoanode of DSSCs owing to enhanced charge transport and collection effects. PMID:25098396

  3. 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

  4. Tailoring micro-mesoporosity in activated carbon fibers to enhance SO? catalytic oxidation.

    PubMed

    Diez, Noel; Alvarez, Patricia; Granda, Marcos; Blanco, Clara; Gryglewicz, Gra?yna; Wrbel-Iwaniec, Iwona; Sliwak, Agata; Machnikowski, Jacek; Menendez, Rosa

    2014-08-15

    Enhanced SO2 adsorption of activated carbon fibers is obtained by tailoring a specific micro-mesoporous structure in the fibers. This architecture is obtained via metal catalytic activation of the fibers with a novel precursor, cobalt naphthenate, which contrary to other precursors, also enhances spinnability and carbon fiber yield. In the SO2 oxidation, it is demonstrated that the combination of micropores and large mesopores is the main factor for an enhanced catalytic activity which is superior to that observed in other similar microporous activated carbon fibers. This provides an alternative way for the development of a new generation of catalytic material. PMID:24910032

  5. 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

  6. 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

  7. Simple template-free synthesis of high surface area mesoporous ceria and its new use as a potential adsorbent for carbon dioxide capture.

    PubMed

    Kamimura, Yoshihiro; Shimomura, Marie; Endo, Akira

    2014-12-15

    The development of an efficient technique for carbon dioxide (CO2) capture from a variety of large stationary sources is in important global issue. If we are to achieve an energy-efficient and effectively higher CO2 capture process based on an adsorption approach, we need new adsorbent materials realistic enough to provide higher CO2 loading on a volumetric basis. For this reason we have focused on the practical use of high surface area mesoporous ceria as a new application in the field of CO2 capture. In this regard, we demonstrate the simple and inexpensive template-free synthesis of mesoporous ceria with a high surface area up to 200 m(2) g(-1), and characterize it as an effective CO2 adsorbent for the first time. The mesoporous ceria is prepared based on sol-gel chemistry, where the product is simply precipitated by the self-assembly of ceria nanoparticles within a short reaction period at room temperature under highly alkaline conditions with optimized chemical compositions. The results of CO2 adsorption-desorption measurement at 298 K show that the obtained ceria with an enhanced surface area exhibits a noticeably higher CO2 adsorption capacity per volume than commercially available non-porous ceria, activated carbon and zeolite 13X over a wide pressure range with robust stability as well as regenerability. This work enables us to prepare promising new materials for the CO2 capture process based on an easy-to-handle synthesis system, and this effective material will have a broad applicability to the efficient CO2 separation from variety of industrial emission sources. The features of the obtained mesoporous ceria are reported and discussed. PMID:25265586

  8. Mesoporous Ge/GeO2/Carbon Lithium-Ion Battery Anodes with High Capacity and High Reversibility.

    PubMed

    Hwang, Jongkook; Jo, Changshin; Kim, Min Gyu; Chun, Jinyoung; Lim, Eunho; Kim, Seongseop; Jeong, Sanha; Kim, Youngsik; Lee, Jinwoo

    2015-05-26

    We report mesoporous composite materials (m-GeO2, m-GeO2/C, and m-Ge-GeO2/C) with large pore size which are synthesized by a simple block copolymer directed self-assembly. m-Ge/GeO2/C shows greatly enhanced Coulombic efficiency, high reversible capacity (1631 mA h g(-1)), and stable cycle life compared with the other mesoporous and bulk GeO2 electrodes. m-Ge/GeO2/C exhibits one of the highest areal capacities (1.65 mA h cm(-2)) among previously reported Ge- and GeO2-based anodes. The superior electrochemical performance in m-Ge/GeO2/C arises from the highly improved kinetics of conversion reaction due to the synergistic effects of the mesoporous structures and the conductive carbon and metallic Ge. PMID:25867753

  9. 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 ? = 50 to ? = -130 (relative to the moving direction). At a moving rate of 2 ?m 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 ?m 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 ? = 50 to ? = -130 (relative to the moving direction). At a moving rate of 2 ?m 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 ?m 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

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

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

    Park, Seok-Hwan; Lee, Wan-Jin

    2015-05-01

    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.

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

    PubMed

    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??m) 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?m(2) 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

  13. 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

  14. 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 2040?nm, length of 30100??m) with ultrafine ferroferric oxide (Fe3O4) nanoparticles (810?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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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 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 C. The formation of nanosized nickel compounds, fully inside the mesopore system, was confirmed with XRD and TEM. An N 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 -1) and 1.5 (50 mV s -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.

  16. 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

  17. Shape control of mesoporous silica nanomaterials templated with dual cationic surfactants and their antibacterial activities.

    PubMed

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

    2015-12-15

    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 activity against mycobacteria. PMID:26364920

  18. 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 ?g mL-1). PMID:26151908

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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 0.2μM to 150μM with a detection limit of 0.05μM (S/N=3). This method was successfully used for determination of BPA leached from drinking bottle and plastic bag with good recoveries. PMID:26653461

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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??mol g-1h-1 and ~99.5% degradation Rhodamine B (RhB) in 60?min, suggesting their promising application in efficient photocatalysts.

  12. 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

  13. High performance sulfur, nitrogen and carbon doped mesoporous anatase-brookite TiO? 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

  14. Immobilization of human carbonic anhydrase on gold nanoparticles assembled onto amine/thiol-functionalized mesoporous SBA-15 for biomimetic sequestration of CO2.

    PubMed

    Vinoba, Mari; Lim, Kyoung Soo; Lee, Si Hyun; Jeong, Soon Kwan; Alagar, Muthukaruppan

    2011-05-17

    A biocatalyst was synthesized by immobilizing human carbonic anhydrase onto gold nanoparticles assembled over amine/thiol-functionalized mesoporous SBA-15. The physicochemical properties of the functionalized mesoporous SBA-15 were obtained by XRD, BET, FE SEM, HR TEM, EDS, and zeta potential analysis. The biocatalytic performance was studied for para-nitrophenyl acetate (p-NPA) hydrolysis. The kinetic parameters K(m) were found to be 22.35 and 27.75 mM, and K(cat)/K(m) values were 1514.09 and 1612.25 M(-1) s(-1) for HCA immobilized on gold nanoparticles assembled on amine/thiol-functionalized mesoporous SBA-15 (HCA/Au/APTES/SBA-15 and HCA/Au/MPTES/SBA-15), respectively. These HCA/Au/APTES/SBA-15 and HCA/Au/MPTES/SBA-15 were investigated for biocatalytic hydration of CO(2) and its precipitation as CaCO(3). The amount of CaCO(3) precipitated over HCA/Au/MPTES/SBA-15 was nearly the same as that precipitated over free HCA. Storage stability and reusability studies suggested that HCA/Au/MPTES/SBA-15 retained its activity even after 20 days storage at 25 C and 20 recycling runs. The present results demonstrate that HCA/Au/MPTES/SBA-15 and HCA/Au/APTES/SBA-15 are highly efficient potential nanobiocatalysts for industrial-scale CO(2) sequestration. PMID:21488617

  15. 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.

  16. 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

  17. A simple synthesis method for nano-metal catalyst supported on mesoporous carbon: the solution plasma process

    NASA Astrophysics Data System (ADS)

    Kang, Jun; Li, Oi Lun; Saito, Nagahiro

    2013-07-01

    High-electrocatalytic-activity noble nanoparticles (NPs) supported on carbon nanoballs (CNBs) were synthesized using an innovative plasma-in-liquid method, which is known as solution plasma processing (SPP). This technique uses a one-step method for the synthesis of NPs on carbon materials. CNBs are formed using benzene as a carbon precursor while gold (Au) or platinum (Pt) nanoparticles are generated instantaneously via sputtering from metal electrodes. The synthesized NP/CNBs were annealed at 850 C in order to increase the conductivity of the material. The results of structural characterizations reveal that the Au and Pt NPs are smaller than 10 nm and have a uniform size distribution, and these NPs are successfully loaded onto highly mesoporous CNBs that have an average pore diameter between 13 and 16 nm. In the results from cyclic voltammetry measurements, the Au/CNBs and Pt/CNBs show clear peaks corresponding to the oxidation and reduction features in the catalytic reactions. Apart from noble nanoparticles, SPP can also be used to synthesize various kinds of NPs including bimetallic NPs loaded on spherical carbon supports by changing the working electrodes. The proposed mechanism for the synthesis is discussed in detail. This method shows potential to be a candidate for the next-generation synthesis of NP/carbon in the future.High-electrocatalytic-activity noble nanoparticles (NPs) supported on carbon nanoballs (CNBs) were synthesized using an innovative plasma-in-liquid method, which is known as solution plasma processing (SPP). This technique uses a one-step method for the synthesis of NPs on carbon materials. CNBs are formed using benzene as a carbon precursor while gold (Au) or platinum (Pt) nanoparticles are generated instantaneously via sputtering from metal electrodes. The synthesized NP/CNBs were annealed at 850 C in order to increase the conductivity of the material. The results of structural characterizations reveal that the Au and Pt NPs are smaller than 10 nm and have a uniform size distribution, and these NPs are successfully loaded onto highly mesoporous CNBs that have an average pore diameter between 13 and 16 nm. In the results from cyclic voltammetry measurements, the Au/CNBs and Pt/CNBs show clear peaks corresponding to the oxidation and reduction features in the catalytic reactions. Apart from noble nanoparticles, SPP can also be used to synthesize various kinds of NPs including bimetallic NPs loaded on spherical carbon supports by changing the working electrodes. The proposed mechanism for the synthesis is discussed in detail. This method shows potential to be a candidate for the next-generation synthesis of NP/carbon in the future. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01229h

  18. Nitrogen-containing mesoporous carbons prepared from melamine formaldehyde resins with CaCl2 as a template.

    PubMed

    Huang, Yu'an; Yang, Feng; Xu, Zheng; Shen, Jianyi

    2011-11-01

    Melamine formaldehyde resins were synthesized with encapsulated CaCl(2) as a template. Carbonization at high temperatures led to the formation of carbon materials containing N atoms. Washing with de-ionized water removed encapsulated CaCl(2), resulting in the formation of mesopores (3-30 nm) with the high surface areas (770-1300 m(2)/g). The template can be recycled and the method is simple and cost effective as compared to the hard template techniques. The mesoporous carbons containing nitrogen (NMC) thus prepared exhibited the amphipathic surfaces (both hydrophilic and lipophilic) and adsorbed great amount of water and benzene. In addition, the incorporated N atoms exhibited quite strong basicity for the adsorption of great amount of SO(2). PMID:21840533

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

    PubMed

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

    2015-12-17

    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 m(2) g(-1)) and large pore volume (1.95-2.53 cm(3) 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 (?0 = 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. PMID:26627870

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  3. Large-Scale, ThreeDimensional, FreeStanding, and Mesoporous Metal Oxide Networks for HighPerformance Photocatalysis

    PubMed Central

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

    2013-01-01

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

  4. Iron Carbide Nanoparticles Encapsulated in Mesoporous Fe-N-Doped Graphene-Like Carbon Hybrids as Efficient Bifunctional Oxygen Electrocatalysts.

    PubMed

    Jiang, Hongliang; Yao, Yifan; Zhu, Yihua; Liu, Yanyan; Su, Yunhe; Yang, Xiaoling; Li, Chunzhong

    2015-09-30

    It is highly crucial and challenging to develop bifunctional oxygen electrocatalysts for oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) in rechargeable metal-air batteries and unitized regenerative fuel cells (URFCs). Herein, a facile and cost-effective strategy is developed to prepare mesoporous Fe-N-doped graphene-like carbon architectures with uniform Fe3C nanoparticles encapsulated in graphitic layers (Fe3C@NG) via a one-step solid-state thermal reaction. The optimized Fe3C@NG800-0.2 catalyst shows comparable ORR activity with the state-of-the-art Pt/C catalyst and OER activity with the benchmarking RuO2 catalyst. The oxygen electrode activity parameter ?E (the criteria for judging the overall catalytic activity of bifunctional electrocatalysts) value for Fe3C@NG800-0.2 is 0.780 V, which surpasses those of Pt/C and RuO2 catalysts as well as those of most nonprecious metal catalysts. Significantly, excellent long-term catalytic durability holds great promise in fields of rechargeable metal-air batteries and URFCs. PMID:26371772

  5. 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.

  6. 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.

  7. 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

  8. Stabilizing Surfactant Templated Cylindrical Mesopores in Polymer and Carbon Films through Composite Formation with Silica Reinforcement

    SciTech Connect

    Song, Lingyan; Feng, Dan; Lee, Hae-Jeong; Wang, Chengqing; Wu, Quanyan; Zhao, Dongyuan; Vogt, Bryan D.

    2010-10-22

    A facile approach to maintain the periodic mesostructure of cylindrical pores in polymer-resin and carbon films after thermal template removal is explored through the reactive coassembly of resol (carbon precursor) and tetraethylorthosilicate (silica precursor) with triblock copolymer Pluronic F127. Without silica, a low porosity, disordered film is formed after pyrolysis despite the presence of an ordered mesostructure prior to template removal. However for silica concentration greater than 25 wt %, pyrolysis at 350 C yields a mesoporous silica-polymer film with well-defined pore mesostructure. These films remain well ordered upon carbonization at 800 C. In addition to the mesostructural stability, the addition of silica to the matrix impacts other morphological characteristics. For example, the average pore size and porosity of the films increase from 3.2 to 7.5 nm and 12 to 45%, respectively, as the concentration of silica in the wall matrix increases from 0 to 32 wt %. The improved thermal stability of the ordered mesostructure with the addition of silica to the matrix is attributed to the reinforcement of the mechanical properties leading to resistance to stress induced collapse of the mesostructure during template removal.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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).

  14. 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.

  15. Ultra-fine Pt nanoparticles supported on ionic liquid polymer-functionalized ordered mesoporous carbons for nonenzymatic hydrogen peroxide detection.

    PubMed

    Bo, Xiangjie; Bai, Jing; Qi, Bin; Guo, Liping

    2011-10-15

    Poly(ionic liquid) (PIL) coated ordered mesoporous carbons (OMCs) were prepared by in situ polymerization of 3-ethyl-1-vinylimidazolium tetrafluoroborate ([VEIM]BF(4)) monomer on OMCs matrix. PIL on the surface of OMCs can provide sufficient binding sites to anchor the precursors of metal ion. PIL/OMCs were employed as support material for the deposition and formation of ultra-fine Pt nanoparticles, via the self-assembly between the negative Pt precursor and positively charged functional groups of PIL-functionalized OMCs. The combination of the unique properties of each component endows Pt/PIL/OMCs as a good electrode material. Compared with the Pt/OMCs nanocomposite, the Pt/PIL/OMCs modified electrode displays high electrocatalytic activity towards hydrogen peroxide (H(2)O(2)) and gives linear range from 1.0 10(-7) to 3.2 10(-3) M (R=0.999). The Pt/PIL/OMCs responds very rapidly to the changes in the level of H(2)O(2), producing steady-state signals within 4-5s. A high sensitivity of 24.43 ?A mM(-1) and low detection limit of 0.08 ?M was obtained at Pt/PIL/OMCs modified electrode towards the reduction of H(2)O(2). The improved activity makes Pt/PIL/OMCs nanocomposite promising for being developed as an attractive robust and new electrode material for electrochemical sensors and biosensors design. PMID:21784627

  16. 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.

  17. 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.

  18. Facile synthesis of gradient mesoporous carbon monolith based on polymerization-induced phase separation

    NASA Astrophysics Data System (ADS)

    Xu, Shunjian; Luo, Yufeng; Zhong, Wei; Xiao, Zonghu; Luo, Yongping; Ou, Hui; Zhao, Xing-Zhong

    2014-06-01

    In this paper, a gradient mesoporous carbon (GMC) monolith derived from the mixtures of phenolic resin (PF) and ethylene glycol (EG) was prepared by a facile route based on polymerization-induced phase separation under temperature gradient (TG). A graded biphasic structure of PF-rich and EG-rich phases was first formed in preform under a TG, and then the preform was pyrolyzed to obtain the GMC monolith. The TG is mainly induced by the thermal resistance of the preferential phase separation layer at high temperature region. The pore structure of the monolith changes gradually along the TG direction. When the TG varies from 58C to 29C, the pore size, apparent porosity and specific surface area of the monolith range respectively from 18 nm to 83 nm, from 32% to 39% and from 140.5 m2/g to 515.3 m2/g. The gradient porous structure of the monolith is inherited from that of the preform, which depends on phase separation under TG in the resin mixtures. The pyrolysis mainly brings about the contraction of the pore size and wall thickness as well as the transformation of polymerized PF into glassy carbon.

  19. 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

  20. 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.

  1. 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.

  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. Formation Regularities of Sers-Active Substrates Based on Silver-Coated Mesoporous Silicon

    NASA Astrophysics Data System (ADS)

    Panarin, A.; Khodasevich, I.; Terekhov, S.; Bandarenka, H.; Artsemyeva, K.; Bondarenko, V.; Martinez-Pastor, J.

    2013-05-01

    SERS-active substrates have been fabricated by immersion deposition of Ag on mesoporous silicon. The SERS intensity has been found to alter simultaneously to the periodical repacking of Ag particles which grow according to the Volmer-Weber mechanism. We have determined the crucial parameter ("effective time") for managing the SERS signal intensity. "Effective time" has been calculated as a product of the immersion time by the Ag salt concentration.

  4. 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

  5. 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 (?) 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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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 m2 g-1, homogeneous pore size of 4.6 nm and a large pore volume of 1.65 cm3 g-1. The advantages of high electrochemical active surface area and favorable accessible porosity of OMC benefit the catalysis of I3- 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 (?) 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.

  7. Lanthanum cobaltite perovskite supported onto mesoporous zirconium dioxide: nature of active sites of VOC oxidation.

    PubMed

    Kustov, Alexander L; Tkachenko, Olga P; Kustov, Leonid M; Romanovsky, Boris V

    2011-08-01

    Novel catalytic nano-sized materials based on LaCoO(x) perovskite nanoparticles incapsulated in the mesoporous matrix of zirconia were prepared, characterized by physicochemical methods and tested in complete methanol oxidation. LaCoO(x) nanoparticles were prepared inside the mesopores of ZrO(2) by decomposition of bimetallic La-Co glycine precursor complexes. The catalysts have been studied by diffuse-reflectance FTIR-spectroscopy using such probe molecules as CO, CD(3)CN and CDCl(3) to test low-coordinated metal ions. At low temperatures of decomposition of complexes (up to 400C), low-coordinated Co(3+) ions predominate in the LaCoO(x) nanoparticles, whereas basically Co(2+) ions are found upon increasing the decomposition temperature to 600C. The novel nano-sized perovskite catalysts exhibit a very high catalytic activity in the abatement of volatile organic compounds present in air, like methanol and light hydrocarbons. PMID:21665054

  8. 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

  9. 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

  10. 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 (RCT) 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 510(-10)-510(-5)M, with a detection limit of 210(-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

  11. 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.

  12. 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

  13. 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

  14. 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

  15. Ultradispersed Palladium Nanoparticles in Three-Dimensional Dendritic Mesoporous Silica Nanospheres: Toward Active and Stable Heterogeneous Catalysts.

    PubMed

    Shen, Dengke; Chen, Lei; Yang, Jianping; Zhang, Renyuan; Wei, Yong; Li, Xiaomin; Li, Wei; Sun, Zhenkun; Zhu, Hongwei; Abdullah, Aboubakr M; Al-Enizi, Abdullah; Elzatahry, Ahmed A; Zhang, Fan; Zhao, Dongyuan

    2015-08-12

    Immobilization of highly monodispersed palladium nanoparticles in colloidal mesoporous silica supports has been successfully achieved. The Pd nanoparticles with a uniform small size of ?1.2 nm can be homogeneously distributed in individual mesopore channels of amino group-functionalized three-dimensional dendritic mesoporous silica nanospheres (3D-dendritic MSNSs) with a Pd content of ?2.8%. The 3D-dendritic MSNSs-based nanoreactors show high activity in Suzuki-Miyaura cross-coupling reactions of bromobenzene with phenylboronic acid, obtaining a yield over 99% with 0.075 mol % Pd catalyst at room temperature in the dark within 12 h. More importantly, the excellent catalytic performance can be maintained with a negligible decrease lasting at least six cycles. It further reveals that the mesoporous frameworks of the colloidal silica supports can be well-preserved after four catalytic runs; meanwhile, the Pd nanoparticles in the mesopore channels also can remain the sizes of 1.50.3 nm without significant transfer and aggregation. The unique mesostructure of the 3D-dendritic MSNSs with mesopore channels of short length and large diameter is supposed to be the key role in immobilization of active and robust heterogeneous catalysts, and it would have more hopeful prospects in catalytic applications. PMID:26192924

  16. Ordered mesoporous carbon modified carbon ionic liquid electrode for the electrochemical detection of double-stranded DNA.

    PubMed

    Zhu, Zhihong; Li, Xia; Zeng, Yan; Sun, Wei

    2010-06-15

    In this paper the direct electrochemistry of double-stranded DNA (dsDNA) was investigated on ordered mesoporous carbon (OMC) modified carbon ionic liquid electrode (CILE). CILE was prepared by mixing graphite powder with 1-ethyl-3-methylimidazolium ethylsulphate ([EMIM]EtOSO(3)) and liquid paraffin. A stable OMC film was formed on the surface of CILE with the help of Nafion to get a modified electrode denoted as Nafion-OMC/CILE. Due to the specific characteristics of OMC and IL present on the electrode surface, the fabricated electrode showed good electrochemical performances to different electroactive molecules. The electrochemical responses of dsDNA were carefully investigated on this electrode with two irreversible oxidation peak appeared at +1.250 V and +0.921 V (vs. SCE), which was corresponding to the oxidation of adenine and guanine residues in dsDNA structure. The electrochemical behaviors of dsDNA were carefully investigated on the Nafion-OMC/CILE. Experimental results indicated that the electron transfer rate was promoted with the increase of the oxidation peak current and the decrease of the oxidation peak potential, which was due to the electrocatalytic ability of OMC on the electrode surface. Under the optimal conditions the oxidation peak current increased with dsDNA concentration in the range of 10.0-600.0 microg mL(-1) by differential pulse voltammetry (DPV) with the detection limit of 1.2 microg mL(-1) (3sigma). PMID:20382013

  17. 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

  18. 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

  19. 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

  20. 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

  1. A microporous-mesoporous carbon with graphitic structure for a high-rate stable sulfur cathode in carbonate solvent-based Li-S batteries.

    PubMed

    Wang, Da-Wei; Zhou, Guangmin; Li, Feng; Wu, Kuang-Hsu; Lu, Gao Qing Max; Cheng, Hui-Ming; Gentle, Ian R

    2012-06-28

    A microporous-mesoporous carbon with graphitic structure was developed as a matrix for the sulfur cathode of a Li-S cell using a mixed carbonate electrolyte. Sulfur was selectively introduced into the carbon micropores by a melt adsorption-solvent extraction strategy. The micropores act as solvent-restricted reactors for sulfur lithiation that promise long cycle stability. The mesopores remain unfilled and provide an ion migration pathway, while the graphitic structure contributes significantly to low-resistance electron transfer. The selective distribution of sulfur in micropores was characterized by X-ray photoelectron spectroscopy (XPS), nitrogen cryosorption analysis, transmission electron microscopy (TEM), X-ray powder diffraction and Raman spectroscopy. The high-rate stable lithiation-delithiation of the carbon-sulfur cathode was evaluated using galvanostatic charge-discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy. The cathode is able to operate reversibly over 800 cycles with a 1.8 C discharge-recharge rate. This integration of a micropore reactor, a mesopore ion reservoir, and a graphitic electron conductor represents a generalized strategy to be adopted in research on advanced sulfur cathodes. PMID:22618882

  2. 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.

  3. 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

  4. Thin-layer polymer wrapped enzymes encapsulated in hierarchically mesoporous silica with high activity and enhanced stability.

    PubMed

    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

  5. 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.

  6. 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

  7. Advanced and economical ambient drying method for controlled mesopore polybenzoxazine-based carbon xerogels: Effects of non-ionic and cationic surfactant on porous structure.

    PubMed

    Thubsuang, Uthen; Ishida, Hatsuo; Wongkasemjit, Sujitra; Chaisuwan, Thanyalak

    2015-12-01

    Polybenzoxazine has been successfully synthesized by a facile quasi-solventless method and used as a precursor for producing carbon xerogels via an ambient drying method, rather than usually used CO2 critical or freeze drying. In this work, we aim to study the effect of non-ionic (Synperonic NP30) and cationic (CTAB) surfactants on porous structure of polybenzoxazine-based carbon xerogels. Of particular interest is the formation of inter-connected structure of mesoporous carbon xerogels with mesopore diameters in the range of 15-36 nm by using different concentrations of the cationic surfactant. In addition, carbon xerogel nanospheres with the size of 50-200 nm are also obtained through the emulsion process. The mesopore diameters start to decrease when the carbon xerogel nanospheres are formed at the cationic surfactant concentration of equal to or exceeding 0.030 M. By using the non-ionic surfactant, the properties of the obtained carbon xerogels are shifted from mesoporous materials for the reference carbon xerogel (no surfactant added) to microporous materials at higher concentrations of the non-ionic surfactant (0.009-0.180 M). The carbon xerogel microspheres with the diameter size of about 2.5 ?m are also obtained through the emulsion process when the concentration of the non-ionic surfactant is at 0.180 M. PMID:26298286

  8. 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.

  9. High psedocapacitance of MnO2 nanoparticles in graphitic disordered mesoporous carbon at high scan rates

    SciTech Connect

    Dai, Sheng; Patel, Mehul; Wang, Xiqing; Slanac, Daniel A; Ferrer, Domingo; Johnston, Keith; Stevenson, Keith J

    2012-01-01

    Nanocomposites composed of MnO{sub 2} and graphitic disordered mesoporous carbon (MnO{sub 2}/C) were synthesized for high total specific capacitance and redox pseudocapacitance (C{sub MnO{sub 2}}) at high scan rates up to 200 mV s{sup -1}. High resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy (EDX) demonstrated that MnO{sub 2} nanodomains were highly dispersed throughout the mesoporous carbon structure. According to HRTEM and X-ray diffraction (XRD), the MnO{sub 2} domains are shown to be primarily amorphous and less than 5 nm in size. For these composites in aqueous 1 M Na{sub 2}SO{sub 4} electrolyte, C{sub MnO{sub 2}} reached 500 F/g{sub MnO{sub 2}} at 2 mV s{sup -1} for 8.8 wt% MnO{sub 2}. A capacitance fade of only 20% over a 100-fold change in scan rate was observed for a high loading of 35 wt% MnO{sub 2} with a C{sub MnO{sub 2}} of 310 F/g{sub MnO{sub 2}} at the highest scan rate of 200 mV s{sup -1}. The high electronic conductivity of the graphitic 3D disordered mesoporous carbon support in conjunction with the thin MnO{sub 2} nanodomains facilitate rapid electron and ion transport offering the potential of improved high power density energy storage pseudocapacitors.

  10. High pseudocapacitance of MnO2 nanoparticles in graphitic disordered mesoporous carbon at high scan rates

    SciTech Connect

    Dai, Sheng; Patel, Mehul; Wang, Xiqing; Slanac, Daniel A; Ferrer, Domingo; Johnston, Keith

    2012-01-01

    Nanocomposites composed of MnO{sub 2} and graphitic disordered mesoporous carbon (MnO{sub 2}/C) were synthesized for high total specific capacitance and redox pseudocapacitance (C{sub MnO{sub 2}}) at high scan rates up to 200 mV s{sup -1}. High resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy (EDX) demonstrated that MnO{sub 2} nanodomains were highly dispersed throughout the mesoporous carbon structure. According to HRTEM and X-ray diffraction (XRD), the MnO{sub 2} domains are shown to be primarily amorphous and less than 5 nm in size. For these composites in aqueous 1 M Na{sub 2}SO{sub 4} electrolyte, C{sub MnO{sub 2}} reached 500 F/g{sub MnO{sub 2}} at 2 mV s{sup -1} for 8.8 wt% MnO{sub 2}. A capacitance fade of only 20% over a 100-fold change in scan rate was observed for a high loading of 35 wt% MnO{sub 2} with a C{sub MnO{sub 2}} of 310 F/g{sub MnO{sub 2}} at the highest scan rate of 200 mV s{sup -1}. The high electronic conductivity of the graphitic 3D disordered mesoporous carbon support in conjunction with the thin MnO{sub 2} nanodomains facilitate rapid electron and ion transport offering the potential of improved high power density energy storage pseudocapacitors.

  11. 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

  12. 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.

  13. Pore size effects on the sorption of supercritical carbon dioxide in mesoporous CPG-10 silica

    SciTech Connect

    Rother, Gernot; Krukowski, Elizabeth G; Wallacher, Dirk; Grimm, Nico; Bodnar, Robert J; Cole, David

    2012-01-01

    Excess sorption isotherms of supercritical carbon dioxide in mesoporous CPG-10 silica glasses with nominal pore sizes of 75 (7.5 nm) and 350 (35 nm) were measured gravimetrically at 35 C and 50 C and pressures of 0-200 bar. Formation of broad maxima in the excess sorption was observed at fluid densities below the bulk critical density. Positive values of excess sorption were measured at bulk densities below about 0.65-0.7 g/cm3, whereas zero and negative values were obtained at higher densities, indicating that the interfacial fluid becomes less dense than the corresponding bulk fluid at high fluid densities. A shift of the excess sorption peak position to higher fluid density is found with increasing pore width. The excess sorption of CO2 normalized to the specific surface area is higher for the 35 nm pore size material, suggesting pore confinement effects. Conversely, the pore volume normalized excess sorption is higher for the 7.5 nm pore size material. Assessment of mean pore density reveals regions of constant pore fluid density, located between the excess sorption peak and the adsorption/depletion transition. Both materials exhibit such regions of constant mean pore fluid density as a function of bulk CO2 density at the lower temperature of 35 C, but not at 50 C. The results of this study suggest that the CO2 storage capacity in quartz-rich reservoirs is higher for sites with low temperature and rock textures characterized by narrow pores with high surface to volume ratios.

  14. 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

  15. 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

  16. 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.

  17. Ordered mesoporous silicas and carbons with large accessible pores templated from amphiphilic diblock copolymer poly(ethylene oxide)-b-polystyrene.

    PubMed

    Deng, Yonghui; Yu, Ting; Wan, Ying; Shi, Yifeng; Meng, Yan; Gu, Dong; Zhang, Lijuan; Huang, Yan; Liu, Chong; Wu, Xiaojing; Zhao, Dongyuan

    2007-02-14

    Highly ordered mesoporous carbons and silicas with ultralarge accessible pores have been successfully synthesized by using laboratory-made poly(ethylene oxide)-b-polystyrene (PEO-b-PS) diblock copolymers as templates via the evaporation-induced self-assembly (EISA) approach. Resols and tetraethyl orthosilicate (TEOS) serve as carbon and silica precursors, respectively. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) measurements show that the mesoporous carbons (denoted as C-FDU-18) possess face centered cubic closed-packing (fcc) mesostructure (Fm3m) with large-domain ordering. N2 sorption isotherms reveal a large mesopore at the mean value of 22.6 nm with a narrow pore-size distribution. Mesoporous silicas (Si-FDU-18) also display a highly ordered fcc closed-packing mesostructure with an ultralarge unit cell (a = 54.6 nm). A hydrothermal recrystallization was introduced for the first time to produce micropores in thick silica walls (approximately 7.7 nm) and thus to generate ultralarge accessible mesopores (30.8 nm). Notably, the amphiphilic diblock copolymer with high molecular weight (PEO125-PS230, 29700 g mol-1) in this report was prepared via a simple method of atom transfer radical polymerization (ATRP). It can be easily available for chemists even without any experience in polymer synthesis. PMID:17243685

  18. 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.

  19. 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

  20. 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

  1. 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 ({approx}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{sup -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.

  2. Mesoporous carbon with spherical pores as a carrier for celecoxib with needle-like crystallinity: improve dissolution rate and bioavailability.

    PubMed

    Zhu, Wenquan; Zhao, Qinfu; Sun, Changshan; Zhang, Zhiwen; Jiang, Tongying; Sun, Jin; Li, Yaping; Wang, Siling

    2014-06-01

    The purposes of this investigation are to design mesoporous carbon (MC) with spherical pore channels and incorporate CEL to it for changing its needlelike crystal form and improving its dissolution and bioavailability. A series of solid-state characterization methods, such as SEM, TEM, DSC and XRD, were employed to systematically investigate the existing status of celecoxib (CEL) within the pore channels of MC. The pore size, pore volume and surface area of samples were characterized by nitrogen physical absorption. Gastric mucosa irritation test was carried out to evaluate the safety of mesoporous carbon as a drug carrier. Dissolution tests and in vivo pharmacokinetic studies were conducted to confirm the improvement in drug dissolution kinetics and oral bioavailability. Uptake experiments were conducted to investigate the mechanism of the improved oral bioavailability. The results of solid state characterization showed that MC was prepared successfully and CEL was incorporated into the mesoporous channels of the MC. The crystallinity of CEL in MC was affected by different loading methods, which involve evaporation method and melting method. The dissolution rate of CEL from MC was found to be significantly higher than that of pure CEL, which attributed to reduced crystallinity of CEL. The gastric mucosa irritation test indicated that the MC caused no harm to the stomach and produced a protective effect on the gastric mucosa. Uptake experiments indicated that MC enhanced the amount of CEL absorbed by Caco-2 cells. Moreover, oral bioavailability of CEL loaded within the MC was approximately 1.59-fold greater than that of commercial CEL. In conclusion, MC was a safe carrier to load water insoluble drug by controlling the crystallinity or crystal form with improvement in drug dissolution kinetics and oral bioavailability. PMID:24863191

  3. 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

  4. 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

  5. Mesoporous silica nanoparticles/hydroxyapatite composite coated implants to locally inhibit osteoclastic activity.

    PubMed

    Zhu, Min; Zhu, Yufang; Ni, Bin; Xie, Ning; Lu, Xuhua; Shi, Jianlin; Zeng, Yi; Guo, Xiang

    2014-04-23

    In an attempt to improve implant-bone integration and accelerate bone fracture healing from resisting osteoclastic resorption point of view, we have employed a novel procedure to develop a mesoporous silica nanoparticles/hydroxyapatite (MSNs/HA) composite coating onto stainless Kirschner wire substrate. Characterizations of the surface microstructures indicated enlarged specific surface area compared to HA-coated wires as control, thus the MSNs/HA composite coated implants are endowed with abilities to locally deliver biomedical substances and enhance fracture healing. Herein, zoledronic acid (ZOL) as a model drug, different doses of which were immobilized in the mesoporous coating toward decreasing osteoclastic resorption activity. The loading capacities of ZOL increased almost eight-folds to that of pure HA coating, and the introduction of MSNs obviously retarded ZOL release to achieve a more sustained release profile. After certain periods of osteoclast like cells co-culturing with ZOL contained wires, tartrat-resistant acid phosphatases (TRAP) staining of polynucleated cells and a pit formation assay were performed to investigate the ZOL dose-dependent anti-resorption activity. The promoted local effect on osteoclasts will be of clinical benefit to support implant integration and bone repair. PMID:24666121

  6. Graphitic Carbon Conformal Coating of Mesoporous TiO2 Hollow Spheres for High-Performance Lithium Ion Battery Anodes.

    PubMed

    Liu, Hao; Li, Wei; Shen, Dengke; Zhao, Dongyuan; Wang, Guoxiu

    2015-10-14

    Rational design and controllable synthesis of TiO2 based materials with unique microstructure, high reactivity, and excellent electrochemical performance for lithium ion batteries are crucially desired. In this paper, we developed a versatile route to synthesize hollow TiO2/graphitic carbon (H-TiO2/GC) spheres with superior electrochemical performance. The as-prepared mesoporous H-TiO2/GC hollow spheres present a high specific surface area (298 m(2) g(-1)), a high pore volume (0.31 cm(3) g(-1)), a large pore size (?5 nm), well-defined hollow structure (monodispersed size of 600 nm and inner diameter of ?400 nm, shell thickness of 100 nm), and small nanocrystals of anatase TiO2 (?8 nm) conformably encapsulated in ultrathin graphitic carbon layers. As a result, the H-TiO2/GC hollow spheres achieve excellent electrochemical reactivity and stability as an anode material for lithium ion batteries. A high specific capacity of 137 mAh g(-1) can be achieved up to 1000 cycles at a current density of 1 A g(-1) (5 C). We believe that the mesoporous H-TiO2/GC hollow spheres are expected to be applied as a high-performance electrode material for next generation lithium ion batteries. PMID:26414170

  7. 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.

  8. 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

  9. 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.

  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. 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

  12. 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

  13. Designed synthesis of carbon-functional magnetic graphene mesoporous silica materials using polydopamine as carbon precursor for the selective enrichment of N-linked glycan.

    PubMed

    Sun, Nianrong; Yao, Jizong; Deng, Chunhui

    2016-02-01

    Glycosylation, which has been confirmed to be associated with many diseases, is an important protein post-translation modification. Taking into account the low abundant of glycan, the purification of complex biological samples is considered to be very significant before mass spectrometry detection. In this work, carbon-functionalized magnetic graphene /mesoporous silica materials (C-Mag G@mSiO2 materials) with high content of carbon were designed and synthesized by using polydopamine as carbon precursor. Taking advantage of the special interaction between carbon and glycan, C-Mag G@mSiO2 materials were successfully applied to enrich N-linked glycans in different complex samples, such as standard glycoprotein digestion, the mixture of standard glycoprotein digestion, glycoprotein and non-glycoprotein, and human serum. PMID:26653470

  14. 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

  15. Polymer/Ordered mesoporous carbon nanocomposite platelets as superior sensing materials for gas detection with surface acoustic wave devices.

    PubMed

    Ku, Pei-Hsin; Hsiao, Chen-Yun; Chen, Mei-Jing; Lin, Tai-Hsuan; Li, Yi-Tian; Liu, Szu-Chieh; Tang, Kea-Tiong; Yao, Da-Jeng; Yang, Chia-Min

    2012-08-01

    We have prepared nanocomposites of polymers and platelet CMK-5-like carbon and have demonstrated their superior performance for gravimetric gas detection. The zirconium-containing platelet SBA-15 was used as hard template to prepare CMK-5-like carbon, which was then applied as a lightweight and high-surface-area scaffold for the growth of polymers by radical polymerization. Mesoporous nanocomposites composed of four different polymers were used as sensing materials for surface acoustic wave devices to detect ppm-level ammonia gas. The sensors showed much better sensitivity and reversibility than those coated with dense polymer films, and the sensor array could still generate a characteristic pattern for the analyte with a concentration of 16 ppm. The results show that the nanocomposite sensing materials are promising for highly sensitive gravimetric-type electronic nose applications. PMID:22835071

  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. Ultra-small gold nanoparticles immobilized on mesoporous silica/graphene oxide as highly active and stable heterogeneous catalysts.

    PubMed

    Peng, Li; Zhang, Jianling; Yang, Shuliang; Han, Buxing; Sang, Xinxin; Liu, Chengcheng; Ma, Xue; Yang, Guanying

    2015-03-14

    Here we demonstrate the in situ formation of ultra-small gold nanoparticles (<2 nm) finely dispersed on a binary solid carrier, i.e. a mesoporous SiO2 coated graphene oxide (GO) nanosheet. The as-synthesized Au-SiO2-GO composite has shown high catalytic activity and reusability for chemical reactions under mild conditions. PMID:25679019

  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. GRANULAR ACTIVATED CARBON INSTALLATIONS

    EPA Science Inventory

    This paper presents a compilation and summary of design criteria, performance, and cost data from 22 operating municipal and industrial granular activated carbon (GAC) installations that treat water and wastewater or process food and beverage products. Guidance for using this inf...

  20. 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.

  1. 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

  2. Water vapor adsorption onto activated carbons prepared from cattle manure compost (CMC)

    NASA Astrophysics Data System (ADS)

    Qian, Qingrong; Sunohara, Satoshi; Kato, Yuichi; Zaini, Muhammad Abbas Ahmad; Machida, Motoi; Tatsumoto, Hideki

    2008-05-01

    Activated carbons were prepared from cattle manure compost (CMC) using zinc chloride activation. The structural and surface chemical characteristics of CMC-based activated carbons were determined by N 2 adsorption-desorption and Boehm titration, respectively. The water vapor adsorption properties of the prepared activated carbons with various pore structure and surface nature were examined, and the mechanism of water adsorbed onto activated carbon was also discussed. The results show that the adsorption of water vapor on carbons begins at specific active sites at low relative humidity (RH), followed by micropore filling at medium RH through the formation of pentamer cluster of water molecules in the narrow micropores. The water vapor adsorption capacity of activated carbon is predominantly dependent on its pore volume and surface area. Although capillary condensation is not the mechanism for water adsorption onto activated carbon, water can adsorb on narrow mesopore to some extent.

  3. 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).

  4. 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

  5. High-temperature hydrothermal synthesis of crystalline mesoporous TiO2 with superior photo catalytic activities

    NASA Astrophysics Data System (ADS)

    Liu, Fujian; Liu, Chun-Lin; Hu, Baowei; Kong, Wei-Ping; Qi, Chen-Ze

    2012-07-01

    Mesoporous titanium dioxide with crystalline mesopore walls (M-TiO2-ns) have been successfully synthesized through the self-assembly of poly 4-Vinylpyridine template and tetrabutyl titanate precursor based on their complex bond interaction under high temperature (180 C) hydrothermal conditions. X-ray diffraction shows that M-TiO2-ns have highly crystalline mesopore walls with anatase phase characters; N2 sorption-desorption isotherms, SEM and TEM images show that M-TiO2-ns have high BET surface areas (85 and 120 m2/g, respectively), large pore volumes (0.32 and 0.34 cm3/g, respectively) and crystalline mesopore walls, which exhibit monolithic morphology with crystal sizes around 3-5 ?m. Interestingly, M-TiO2-ns exhibit much higher catalytic activities and good recyclability in both induced reduction of decabromodiphenyl and oxidation of Rhodamine B under UV light than those of nonporous crystalline TiO2 and M-TiO2 templated by hydrocarbon surfactant of F127, which is even comparable with that of commercial P25. Combination of the unique characters such as crystallinity, stable mesostructure, large BET surface areas and superior photo catalytic activities make M-TiO2-ns a kind of potentially important material for removing of organic pollutions in environment through green photo irradiation processes.

  6. 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

  7. 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.

  8. 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.

  9. Mesoporous poly(melamine-formaldehyde) solid sorbent for carbon dioxide capture.

    PubMed

    Tan, Mei Xuan; Zhang, Yugen; Ying, Jackie Y

    2013-07-01

    Feed the pore: A highly mesoporous melamine-formaldehyde resin is synthesized through a simple, one-step polycondensation reaction by using inexpensive and abundant common industrial chemicals. The material is demonstrated to have a high surface area and a well-defined pore structure. Its high density of CO2 binding pockets with low CO2 binding energy facilitates rapid and reversible CO2 sorption. PMID:23757327

  10. Mesoporous CdS-pillared H2Ti3O7 nanohybrids with efficient photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Lin, Bizhou; Zhou, Yi; He, Liwen; Yang, Weiwei; Chen, Yilin; Gao, Bifen

    2015-04-01

    Heterostructured CdS-pillared H2Ti3O7 nanohybrids were prepared by the self-assembly of exfoliated trititanate nanosheets and CdS nanosol particles under the electrostatic interactions. It was revealed that the present nanohybrids were mesoporous with specific surface areas of about 90 m2 g-1. The nanohybrids exhibited high photocatalytic activity and good recurrence stability in the H2 evolution from water splitting. When the preparation molar ratio of H2Ti3O7/CdS was 2:1, the nanohybrid reached a high H2-evolution rate of 1523 ?mol h-1 g-1 under a 300 W Xe lamp irradiation, which was 13 times higher than the bare CdS. Apart from the wider spectral responsive range, the superior photocatalytic performance of the nanohybrids was predominantly attributed to the efficient photogenerated charge separation between the trititanate nanosheets and the encapsulated CdS nanoparticles.

  11. 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

  12. 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

  13. Determining activated carbon performance

    SciTech Connect

    Naylor, W.F.; Rester, D.O.

    1995-07-01

    This article discusses the key elements involved in evaluating a system`s performance. Empty bed contact time (EBCT) is a term used to describe the length of time a liquid stream being treated is in contact with a granular activated carbon bed. The EBCT is the time required for a fluid to pass through the volume equivalent of the media bed, without the media being present. In a bed of granular activated carbon, the void volume or space between particles is usually about 45 percent. Therefore, the EBCT is about twice the true or actual time of contact between the fluid being treated and the GAC particles. The EBCT plays an important role in determining the effectiveness and longevity of granular activated carbon (GAC) used to treat liquids in a fixed-bed adsorber. Factors that influence and are influenced by EBCT, and their relationship to GAC performance in a treatment scheme include: adsorption, mass transfer zone, impurity concentration, adsorption affinity, flow rate and system design considerations.

  14. 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

  15. Bifunctional Mesoporous Carbon Nitride: Highly Efficient Enzyme-like Catalyst for One-pot Deacetalization-Knoevenagel Reaction.

    PubMed

    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

  16. Bifunctional Mesoporous Carbon Nitride: Highly Efficient Enzyme-like Catalyst for One-pot Deacetalization-Knoevenagel Reaction

    NASA Astrophysics Data System (ADS)

    Zhong, Lin; Anand, Chokkalingam; Lakhi, Kripal Singh; Lawrence, Geoffrey; Vinu, Ajayan

    2015-08-01

    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 MCNs 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.

  17. 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

  18. Carbon Paste Electrode Modified with Carbamoylphosphonic Acid Functionalized Mesoporous Silica: A New Mercury-Free Sensor for Uranium Detection

    SciTech Connect

    Yantasee, Wassana; Lin, Yuehe; Fryxell, Glen E.; Wang, Zheming

    2004-05-20

    This study reports a new approach for developing a uranium (U(VI)) electrochemical sensor that is mercury-free, solid-state, and has less chance for ligand depletion than existing sensors. A carbon-paste electrode modified with carbamoylphosphonic acid self-assembled monolayer on mesoporous silica was developed for uranium detection based on an adsorptive square-wave stripping voltammetry technique. Voltammetric responses for U(VI) detection are reported as a function of pH, preconcentration time, and aqueous phase U(VI) concentration. The uranium detection limit is 25 ppb after 5 minutes preconcentration and improved to 1 ppb after 20 minutes preconcentration. The relative standard deviations are normally less than 5%.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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 25-65C and inlet CO2 concentration range of 10-30mol% 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 273K, 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 0.62cm(3)/g and surface area of 1400m(2)/g had the highest CO2 adsorption capacity of 1.8mol/kg due to its microporous structure and high surface area under the optimized experimental conditions of 30mol% CO2 and 25C. 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 50cycles with low temperature (160C) regeneration. PMID:26257348

  4. Visible-light-driven surface reconstruction of mesoporous TiO2: toward visible-light absorption and enhanced photocatalytic activities.

    PubMed

    Li, Renhong; Kobayashi, Hisayoshi; Guo, Junfang; Fan, Jie

    2011-08-14

    The surface structure of mesoporous TiO(2) is reconstructed via a visible-light-driven reaction with benzyl alcohol molecules at mild, anaerobic conditions, which substantially extends its visible-light absorption and photocatalytic activities. PMID:21709863

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. Ammonia-treated Ordered Mesoporous Carbons as Catalytic Materials for Oxygen Reduction Reaction

    SciTech Connect

    Wang, Xiqing; Lee, Je Seung; Zhu, Qing; Liu, Jun; Wang, Yong; Dai, Sheng

    2010-04-13

    Polymer electrolyte membrane fuel cells (PEMFCs) have been considered as promising alternative power sources for many mobile and stationary applications. Compared to the fast hydrogen oxidation at the anode, the sluggish oxygen reduction reaction (ORR) at the cathode requires high-performance catalysts. Currently, platium (Pt) nanoparticles supported on high surface area carbons remain the best catalysts for ORR. However, both instability and high cost of Pt-based catalysts represent two main obstacles limiting the commercial applications of PEMFCs. The instability of supported Pt catalysts is mainly due to the corrosion of carbon support under operation conditions and the agglomation and detachment of Pt particles, leading to a decrease in catalytic surface areas. Development of corrosion resistant supports and enhancement of the interactions between Pt and supports are two strategies to improve the cathode long-term activity.

  10. Voltammetric detection of lead (II) and mercury (II) using a carbon paste electrode modified with thiol self-assembled monolayer on mesoporous silica (SAMMS)

    SciTech Connect

    Yantasee, Wassana; Lin, Yuehe; Zemanian, Thomas S.; Fryxell, Glen E.

    2003-05-02

    The anodic stripping voltammetry at a carbon paste electrode modified with thiol terminated self-assembled monolayer on mesoporous silica (SH-SAMMS) provides a new sensor for simultaneous detection of lead (Pb2+) and mercury (Hg2+) in aqueous solutions. The overall analysis involved a two-step procedure: an accumulation step at open circuit, followed by medium exchange to a pure electrolyte solution for the stripping analysis. Factors affecting the performance of the SH-SAMMS modified electrodes were investigated, including electrode activation and regeneration, electrode composition, preconcentration time, electrolysis time, and composition of electrolysis and stripping media. The most sensitive and reliable electrode contained 20% SH-SAMMS and 80% carbon paste. The optimal operating conditions were a sequence with a 2-5 minute preconcentration period, then a 60-second electrolysis period of the preconcentrated species in 0.2 M nitric acid, followed by square wave anodic stripping voltammetry from 1.0 V to 0.6 V in 0.2 M nitric acid. The areas of the peak responses were linear with respect to metal ion concentrations in the ranges of 10-1500 ppb Pb2+ and 20-1600 ppb Hg2+. The detection limits for Pb2+ and Hg2+ were 0.5 ppb Pb2+ and 3 ppb Hg2+ after a 20-minute preconcentration period.

  11. 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.

  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. 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

  14. 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

  15. 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

  16. 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)

  17. Hierarchical nanospheres based on Pd nanoparticles dispersed on carbon coated magnetite cores with a mesoporous ceria shell: a highly integrated multifunctional catalyst.

    PubMed

    Li, Yinle; Zhang, Zhuqing; Shen, Jianfeng; Ye, Mingxin

    2015-10-01

    The design and fabrication of core-shell nanostructures with steerable morphologies and tailored performances have aroused abundant scientific studies for organic transformations. We here report the preparation of multifunctional and highly efficient core-shell microspheres, which bear a carbon-protected magnetic Fe3O4 core, a transition layer of active Pd nanoparticles (NPs) and an outer shell of mesoporous CeO2 (mCeO2). The composition and structure of the as-prepared Fe3O4@C-Pd@mCeO2 were thoroughly characterized by X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and Brunauer-Emmett-Teller measurements. The well-designed microspheres have high dispersibility, convenient magnetic separability and good reusability as heterogeneous nanoreactors due to their unique structure. We illustrate the high efficiency of these nanocomposites in mediating the Suzuki-Miyaura cross-coupling reaction and the reduction reaction of 4-nitrophenol (4-NP). The enhanced catalytic activity can be attributed to the synergistic effect between the CeO2 nanoparticles and noble metal NPs. A mechanism was further proposed to explain the improved catalytic activity. This peculiar core-shell nanostructure renders the nanospheres to be an approachable and attractive catalyst system for various catalytic organic industrial processes. PMID:26331890

  18. 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.

  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. Stabilisation of amorphous ibuprofen in Upsalite, a mesoporous magnesium carbonate, as an approach to increasing the aqueous solubility of poorly soluble drugs.

    TOXLINE Toxicology Bibliographic Information

    Zhang P; Forsgren J; Strmme M

    2014-09-10

    One attractive approach to increase the aqueous solubility and thus the bioavailability of poorly soluble drugs is to formulate them in their amorphous state since amorphous compounds generally exhibit higher apparent solubilities than their crystalline counterparts. In the current work, mesoporous magnesium carbonate was used to stabilise the amorphous state of the model substance ibuprofen. Crystallisation of the drug was completely supressed in the formulation, resulting in both a higher apparent solubility and a three times faster dissolution rate of the drug where the drug release was shown to be diffusion controlled. It was also shown that the formulation is stable for at least three months when stored at 75% relative humidity. The simple synthesis together with a high loading capacity and narrow pore size distribution of the mesoporous magnesium carbonate is foreseen to offer great advantages in formulations of poorly soluble drugs.

  1. Aerosol-Assisted Heteroassembly of Oxide Nanocrystals and Carbon Nanotubes into 3D Mesoporous Composites for High-Rate Electrochemical Energy Storage.

    PubMed

    Jia, Xilai; Zhu, Xiao; Cheng, Yanhua; Chen, Zheng; Ning, Guoqing; Lu, Yunfeng; Wei, Fei

    2015-07-01

    Nanostructured composites built from ordinary building units have attracted much attention because of their collective properties for critical applications. Herein, we have demonstrated the heteroassembly of carbon nanotubes and oxide nanocrystals using an aerosol spray method to prepare nanostructured mesoporous composites for electrochemical energy storage. The designed composite architectures show high conductivity and hierarchically structured mesopores, which achieve rapid electron and ion transport in electrodes. Therefore, as-synthesized carbon nanotube/TiO2 electrodes exhibit high rate performance through rapid Li(+) intercalation, making them suitable for ultrafast energy storage devices. Moreover, the synthesis process provides a broadly applicable method to achieve the heteroassembly of vast low-dimensional building blocks for many important applications. PMID:25777365

  2. Stabilisation of amorphous ibuprofen in Upsalite, a mesoporous magnesium carbonate, as an approach to increasing the aqueous solubility of poorly soluble drugs.

    PubMed

    Zhang, Peng; Forsgren, Johan; Strmme, Maria

    2014-09-10

    One attractive approach to increase the aqueous solubility and thus the bioavailability of poorly soluble drugs is to formulate them in their amorphous state since amorphous compounds generally exhibit higher apparent solubilities than their crystalline counterparts. In the current work, mesoporous magnesium carbonate was used to stabilise the amorphous state of the model substance ibuprofen. Crystallisation of the drug was completely supressed in the formulation, resulting in both a higher apparent solubility and a three times faster dissolution rate of the drug where the drug release was shown to be diffusion controlled. It was also shown that the formulation is stable for at least three months when stored at 75% relative humidity. The simple synthesis together with a high loading capacity and narrow pore size distribution of the mesoporous magnesium carbonate is foreseen to offer great advantages in formulations of poorly soluble drugs. PMID:24950364

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. Engineering of Hollow Mesoporous Silica Nanoparticles for Remarkably Enhanced Tumor Active Targeting Efficacy

    PubMed Central

    Chen, Feng; Hong, Hao; Shi, Sixiang; Goel, Shreya; Valdovinos, Hector F.; Hernandez, Reinier; Theuer, Charles P.; Barnhart, Todd E.; Cai, Weibo

    2014-01-01

    Hollow mesoporous silica nanoparticle (HMSN) has recently gained increasing interests due to their tremendous potential as an attractive nano-platform for cancer imaging and therapy. However, possibly due to the lack of efficient in vivo targeting strategy and well-developed surface engineering techniques, engineering of HMSN for in vivo active tumor targeting, quantitative tumor uptake assessment, multimodality imaging, biodistribution and enhanced drug delivery have not been achieved to date. Here, we report the in vivo tumor targeted positron emission tomography (PET)/near-infrared fluorescence (NIRF) dual-modality imaging and enhanced drug delivery of HMSN using a generally applicable surface engineering technique. Systematic in vitro and in vivo studies have been performed to investigate the stability, tumor targeting efficacy and specificity, biodistribution and drug delivery capability of well-functionalized HMSN nano-conjugates. The highest uptake of TRC105 (which binds to CD105 on tumor neovasculature) conjugated HMSN in the 4T1 murine breast cancer model was ~10%ID/g, 3 times higher than that of the non-targeted group, making surface engineered HMSN a highly attractive drug delivery nano-platform for future cancer theranostics. PMID:24875656

  8. 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.

  9. Light- and pH-activated intracellular drug release from polymeric mesoporous silica nanoparticles.

    PubMed

    Tian, Ye; Kong, Yi; Li, Xiaojian; Wu, Jun; Ko, Alex C-T; Xing, Malcolm

    2015-10-01

    Surface modified mesoporous silica nanoparticles (MSNs) with reduced toxicity were prepared for light and pH dual triggerable drug delivery system. Both 413 nm light and acidic environment can activate the drug release process, improving the pharmacological action. By applying rhodamine B (RhB) as a model drug, the accumulative RhB release is as high as 95% in pH 5.0 and in irradiation of 413 nm light, compared to only 55% in pH 7.4 and in dark. The anti-cancer drug camptothecin (CPT) loaded nanoparticles can kill cancer cells with IC?? value of 0.02 ?g mL(-1) in exposure of 413 nm light, which is much lower than free CPT (about 0.1 ?g mL(-1)). Multimodal nonlinear optical imaging microscopy (NLOM) was employed to acquire in vitro coherent anti-Stokes Raman (CARS) and two-photon excited fluorescence (TPEF) images of live MCF-7 cells and showed that the nanoparticles can be taken up by breast tumor cell MCF-7 with high efficiency, indicating its great potential for anti-cancer drug delivery system. PMID:26188470

  10. Heterostructures of Ag?PO?/TiO? mesoporous spheres with highly efficient visible light photocatalytic activity.

    PubMed

    Li, Yanjuan; Yu, Liangmin; Li, Nan; Yan, Wenfu; Li, Xiaotian

    2015-07-15

    Heterostructured Ag3PO4/m-TiO2 (mesoporous sphere) visible-light photocatalyst has been synthesized via a facile method. The resultant composite consists of numerous Ag3PO4 nanoparticles with diameter less than 10nm, and these nanoparticles deposit onto the TiO2 nanoparticles surface forming a heterostructure. N2 adsorption-desorption measurements have suggested that the composite was porous with relative high surface area. Studies of the photocatalytic activity and stability of heterostructured Ag3PO4/m-TiO2 for the degradation of methylene blue (MB) have indicated that its visible light photocatalytic performance was improved compared with pure Ag3PO4 and Ag3PO4/m-TiO2, and exhibited excellent photocatalytic stability. The performance was improved attributing to three aspects: (1) the large specific surface area enhanced the adsorption of MB; (2) numerous pores enlarged the contact area between photocatalyst and MB; (3) the most importantly, depositing Ag3PO4 onto the surface of TiO2 facilitated the separation of electron and hole pairs, which also elevates the photocatalytic performance. Furthermore, the photocatalytic mechanism also has been discussed. Compare with Ag3PO4, the Ag weight percent of Ag3PO4/m-TiO2 decreases from 77% to 20.8%, significantly reducing the cost of photocatalyst. PMID:25823728

  11. 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

  12. Adsorption of naphthenic acids on high surface area activated carbons.

    PubMed

    Iranmanesh, Sobhan; Harding, Thomas; Abedi, Jalal; Seyedeyn-Azad, Fakhry; Layzell, David B

    2014-01-01

    In oil sands mining extraction, water is an essential component; however, the processed water becomes contaminated through contact with the bitumen at high temperature, and a portion of it cannot be recycled and ends up in tailing ponds. The removal of naphthenic acids (NAs) from tailing pond water is crucial, as they are corrosive and toxic and provide a substrate for microbial activity that can give rise to methane, which is a potent greenhouse gas. In this study, the conversion of sawdust into an activated carbon (AC) that could be used to remove NAs from tailings water was studied. After producing biochar from sawdust by a slow-pyrolysis process, the biochar was physically activated using carbon dioxide (CO2) over a range of temperatures or prior to producing biochar, and the sawdust was chemically activated using phosphoric acid (H3PO4). The physically activated carbon had a lower surface area per gram than the chemically activated carbon. The physically produced ACs had a lower surface area per gram than chemically produced AC. In the adsorption tests with NAs, up to 35mg of NAs was removed from the water per gram of AC. The chemically treated ACs showed better uptake, which can be attributed to its higher surface area and increased mesopore size when compared with the physically treated AC. Both the chemically produced and physically produced AC provided better uptake than the commercially AC. PMID:24766592

  13. 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

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. Hierarchically mesoporous carbon nanofiber/Mn3O4 coaxial nanocables as anodes in lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Park, Seok-Hwan; Lee, Wan-Jin

    2015-05-01

    Carbon nanofiber/Mn3O4 (CNF/Mn3O4) coaxial nanocables with a three-dimensional (3D) structure are prepared for lithium ion batteries by electrophoretic deposition on an electrospun CNF cathode followed by heat treatment in air. The bark-like Mn3O4 shell with a thickness of 30 nm surrounds the CNFs with a diameter of 200 nm; this hierarchically mesoporous Mn3O4 shell consisted of interconnected nanoparticles grows radially toward the CNF core when viewed from the cross-section of the coaxial cables. The charge transfer resistance of the CNF/Mn3O4 is much smaller than that of the Mn3O4 powder, because of (i) the abundant inner spaces provided via the formation of the 3D coaxial core/shell nanocables, (ii) the high electric pathway for the Mn3O4 nanoparticles attained with the 1D CNFs, and (iii) the structural stability obtained through the cushioning effect created by the CNF/Mn3O4 coaxial morphology. These unique characteristics contribute to achieving a high capacity, excellent cyclic stability, and good rate capability. The CNF/Mn3O4 nanocables deliver an initial capacity of 1690 mAh g-1 at a current density of 100 mA g-1 and maintain a high reversible capacity of 760 mAh g-1 even after 50 charge-discharge cycles without showing any obvious decay.

  19. The electrochemical reactions of SnO2 with Li and Na: a study using thin films and mesoporous carbons

    SciTech Connect

    Gorka, Joanna; Baggetto, Loic; Keum, Jong Kahk; 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.

  20. Activated carbons obtained from sewage sludge by chemical activation: gas-phase environmental applications.

    PubMed

    Boualem, T; Debab, A; Martnez 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

  1. 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.

  2. 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

  3. Sensitive electrochemical microbial biosensor for p-nitrophenylorganophosphates based on electrode modified with cell surface-displayed organophosphorus hydrolase and ordered mesopore carbons.

    PubMed

    Tang, Xiangjiang; Zhang, Tingting; Liang, Bo; Han, Dongfei; Zeng, Lingxing; Zheng, Cheng; Li, Tie; Wei, Mingdeng; Liu, Aihua

    2014-10-15

    A novel electrochemical microbial biosensor for the rapid monitoring of p-nitrophenyl-substituted organophosphates (OPs) compounds based on glass carbon electrode (GCE) modified with both ordered mesopore carbons (OMCs) and cell surface-expressed organophosphorus hydrolase (OPH) (OPH-bacteria/OMCs/GCE) was described in this paper. The genetically engineered Escherichia coli strain surface displayed mutant OPH (S5) with improved enzyme activity and favorable stability was constructed using a newly identified N-terminal of ice nucleation protein as an anchoring motif, which can be used directly without further time-consuming enzyme-extraction and purification, thereafter greatly improved the stability of the enzyme. Compared to OPH-bacteria modified GCE (OPH-bacteria/GCE), the OPH-bacteria/OMCs/GCE not only significantly enhanced the current response but also reduced the oxidation overpotential towards oxidizable p-nitrophenol (p-NP), which was the hydrolysate of p-nitrophenyl-substituted OPs. Under the optimized experimental conditions, at +0.84 V (vs. SCE), the current-time curve was performed with varying OPs concentration. The current response was linear with paraoxon concentration within 0.05-25 ?M. Similarly, linear range of 0.05-25 ?M was found for parathion, and 0.08-30 ?M for methyl parathion. The low limits of detection were evaluated to be 9.0 nM for paraoxon, 10nM for parathion and 15 nM for methyl parathion (S/N=3). Thus, a highly specific, sensitive and rapid microbial biosensor was established, which holds great promise for on-site detection of trace p-nitrophenyl-substituted OPs. PMID:24794405

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. Controlling morphology, mesoporosity, crystallinity, and photocatalytic activity of ordered mesoporous TiO{sub 2} films prepared at low temperature

    SciTech Connect

    Elgh, Bjrn; Yuan, Ning; Palmqvist, Anders E. C.; Cho, Hae Sung; Terasaki, Osamu; Magerl, David; Philipp, Martine; Mller-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%.

  10. 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

  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. 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.

  13. 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

  14. 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

  15. 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

  16. Mesoporous materials and electrochemistry.

    PubMed

    Walcarius, Alain

    2013-05-01

    Ordered mesoporous materials prepared by the template route have attracted increasing interest from the electrochemists community due to their plenty of unique properties and functionalities that can be effectively exploited in electrochemical devices. This review will cover the whole field of the intersection between electrochemistry and ordered mesoporous materials. The latter are either electronically insulating (silica and some other metal oxides, as well as silica-based organic-inorganic hybrid materials), semi-conducting (metal oxides), or conducting (metals, carbons). The three main intersection areas are: (1) the development/use of electrochemical methods to characterize the properties of mesoporous materials (i.e., charge and mass transfer processes); (2) the generation of mesostructured solids by electro-assisted deposition using appropriate templates; and (3) the application of these novel materials for electrochemical purposes. The most common devices to date are based on a bulk composite or thin film configuration and the resulting electrodes modified with such mesoporous materials have been successfully applied in various fields, including mainly electrochemical sensing and biosensing as well as energy conversion and storage (620 references). PMID:23334166

  17. 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.

  18. 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 ?m 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 ?g/L), low detection limits (0.01-0.05 ?g/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

  19. 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

  20. 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

  1. 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

  2. Multiscale anode materials in lithium ion batteries by combining micro- with nanoparticles: design of mesoporous TiO2 microfibers@nitrogen doped carbon composites.

    PubMed

    Cheng, Wei; Rechberger, Felix; Primc, Darinka; Niederberger, Markus

    2015-09-01

    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. PMID:26220269

  3. 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

  4. 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

  5. Catalytically active Au-O(OH)x-species stabilized by alkali ions on zeolites and mesoporous oxides.

    PubMed

    Yang, Ming; Li, Sha; Wang, Yuan; Herron, Jeffrey A; Xu, Ye; Allard, Lawrence F; Lee, Sungsik; Huang, Jun; Mavrikakis, Manos; Flytzani-Stephanopoulos, Maria

    2014-12-19

    We report that the addition of alkali ions (sodium or potassium) to gold on KLTL-zeolite and mesoporous MCM-41 silica stabilizes mononuclear gold in Au-O(OH)x-(Na or K) ensembles. This single-site gold species is active for the low-temperature (<200C) water-gas shift (WGS) reaction. Unexpectedly, gold is thus similar to platinum in creating -O linkages with more than eight alkali ions and establishing an active site on various supports. The intrinsic activity of the single-site gold species is the same on irreducible supports as on reducible ceria, iron oxide, and titania supports, apparently all sharing a common, similarly structured gold active site. This finding paves the way for using earth-abundant supports to disperse and stabilize precious metal atoms with alkali additives for the WGS and potentially other fuel-processing reactions. PMID:25431492

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

    PubMed

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

    2012-09-01

    [Pt(tpy)Cl]Cl (tpy: terpyridine) was successfully anchored to a series of mesoporous-silica materials that were modified with (3-aminopropyl)triethoxysilane with the aim of developing new inorganic-organic hybrid photocatalysts. Herein, the relationship between the luminescence characteristics and photocatalytic activities of these materials is examined as a function of Pt loading to define the spatial distribution of the Pt complex in the mesoporous channel. At low Pt loading, the Pt complex is located as an isolated species and exhibits strong photoluminescence emission at room temperature owing to metal-to-ligand charge-transfer ((3)MLCT) transitions (at about 530 nm). Energy- and/or electron-transfer from (3)MLCT to O(2) generate potentially active oxygen species, which are capable of promoting the selective photooxidation of styrene derivatives. On the other hand, short PtPt interactions are prominent at high loading and the metal-metal-to-ligand charge-transfer ((3)MMLCT) transition is at about 620 nm. Such Pt complexes, which are situated close to each other, efficiently catalyze H(2)-evolution reactions in aqueous media in the presence of a sacrificial electron donor (EDTA) under visible-light irradiation. This study also investigates the effect of nanoconfinement on anchored guest complexes by considering the differences between the pore dimensions and structures of mesoporous-silica materials. PMID:22865673

  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. 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.

  9. Ruthenium carbenes supported on mesoporous silicas as highly active and selective hybrid catalysts for olefin metathesis reactions under continuous flow.

    PubMed

    Bru, Miriam; Dehn, Richard; Teles, J Henrique; Deuerlein, Stephan; Danz, Manuel; Mller, Imke B; Limbach, Michael

    2013-08-26

    In the search for a highly active and selective heterogenized metathesis catalyst, we systematically varied the pore geometry and size of various silica-based mesoporous (i.e., MCM-41, MCM-48, and SBA-15) and microporous (ZSM-5 and MWW) versus macroporous materials (D11-10 and Aerosil 200), besides other process parameters (temperature, dilution, and mean residence time). The activity and, especially, selectivity of such "linker-free" supports for ruthenium metathesis catalysts were evaluated in the cyclodimerization of cis-cyclooctene to form 1,9-cyclohexadecadiene, a valuable intermediate in the flavor and fragrance industry. The optimized material showed not only exceptionally high selectivity to the valuable product, but also turned out to be a truly heterogeneous catalyst with superior activity relative to the unsupported homogeneous complex. PMID:23852995

  10. 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

  11. 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.

  12. 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

  13. 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

  14. [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

  15. 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

  16. 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

  17. Mesoporous Titanium Oxide-Carbon Nanotubes Soot Films Dried under Gravity and Supergravity Conditions

    NASA Astrophysics Data System (ADS)

    Vargas, M.; Rincn, M. E.; Snchez, M.; Hernndez, G.; Ramos, E.

    2008-02-01

    The use of surfactant emulsions as templates to create highly porous titanium dioxide films deposited in stainless steel substrates is described. Polycondensations of sol-gel titanium oxide occurs around emulsion droplets, which create voids in the final material. A second layer of carbon nanotubes soot dispersed in the surfactant creates a tandem system consisting of a reflector/porous/matrix/absorbing layer. The drying process for these films is performed in tilted and horizontal planes for two hours; one of the drying protocols was designed to be under terrestrial gravity conditions and in the other protocol, samples were dried on a centrifuge with 1.3 g and 7 g. In this work we compared the set of reflectance curves, SEM images and the thicknesses of the films just described.

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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 40-50nm 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

  4. 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

  5. Synthesis of composites SBA-15 mesoporous particles carrying oxytocin and evaluation of their properties, functions, and in vitro biological activities.

    PubMed

    Qian, Ming; Liu, Min; Duan, Mengna; Wu, Zhe; Zhou, Yanmin

    2015-01-01

    Using the organic template method, we have synthesized mesoporous SBA-15 particles and characterized them by scanning electron microscopy and transmission electron microscopy. The bone metabolism regulating hormone oxytocin (OT) was selected as a model for preparation of drug/SBA-15 complexes. The process of drug loading was studied using X-ray diffraction and nitrogen absorption methods. Optimal drug loading parameters were experimentally investigated. The kinetics of drug release from the carrier was evaluated. Finally, the extractions of SBA-15 particles were tested for cytotoxicity, in vitro hemolysis, and the direct attachment toxicity. Our findings suggest that SBA-15 materials have good biocompatibility. Moreover, we demonstrated that OT/SBA-15 complex can stimulate alkaline phosphatase activity in osteoblast cells. The study provides fundamental information for further in vivo drug-carrier testing. PMID:25138676

  6. Synthesis, photophysical characterization, and photoinduced antibacterial activity of methylene blue-loaded amino- and mannose-targeted mesoporous silica nanoparticles.

    PubMed

    Planas, Oriol; Bresol-Obach, Roger; Nos, Jaume; Gallavardin, Thibault; Ruiz-Gonzlez, Rubn; Agut, Montserrat; Nonell, Santi

    2015-01-01

    Over the last 20 years, the number of pathogenic multi-resistant microorganisms has grown steadily, which has stimulated the search for new strategies to combat antimicrobial resistance. Antimicrobial photodynamic therapy (aPDT), also called photodynamic inactivation, is emerging as a promising alternative to treatments based on conventional antibiotics. We have explored the effectiveness of methylene blue-loaded targeted mesoporous silica nanoparticles (MSNP) in the photodynamic inactivation of two Gram negative bacteria, namely Escherichia coli and Pseudomonas aeruginosa. For E. coli, nanoparticle association clearly reduced the dark toxicity of MB while preserving its photoinactivation activity. For P. aeruginosa, a remarkable difference was observed between amino- and mannose-decorated nanoparticles. The details of singlet oxygen production in the nanoparticles have been characterized, revealing the presence of two populations of this cytotoxic species. Strong quenching of singlet oxygen within the nanoparticles is observed. PMID:25859784

  7. Pore size control of Pitch-based activated carbon fibers by pyrolytic deposition of propylene

    NASA Astrophysics Data System (ADS)

    Xie, Jinchuan; Wang, Xuhui; Deng, Jiyong; Zhang, Lixing

    2005-08-01

    In this paper, we attempted to narrow the pore size of Pitch-based activated carbon fiber (Pitch-ACF) by chemical vapor deposition (CVD) of propylene at 700 C. The BET equation was used to estimate the specific surface areas. The micropore volumes were determined using DR equation, t-plot and ? s-plot, and mesopore surface areas were determined by t-plot and ? s-plot. The pore size distribution (PSD) of micropores and mesopore was investigated by micropore analysis method (MP method) and MK method, respectively. The relation between the graphite-like crystal interlayer distance and pore size was analyzed by X-ray diffraction (XRD). The results showed that the pore size of Pitch-ACF was gradually narrowed with increasing deposition time. The catalytic activation of Ni was attempted when Pitch-ACF was modified simultaneously by pyrolysis of propylene. The results obtained from the analysis of PSD of micropores, mesopores and macropores in Ni-P-ACF by density function theory (DFT) showed that the pore structure and surface chemistry were greatly changed due to introducing nickel catalyst.

  8. 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.

  9. 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.

  10. Porous carbon nitride nanosheets for enhanced photocatalytic activities

    NASA Astrophysics Data System (ADS)

    Hong, Jindui; Yin, Shengming; Pan, Yunxiang; Han, Jianyu; Zhou, Tianhua; Xu, Rong

    2014-11-01

    Porous carbon nitride nanosheets (PCNs) have been prepared for the first time by a simple liquid exfoliation method via probe sonication. These mesoporous nanosheets of around 5 nm in thickness combine several advantages including high surface area, enhanced light absorption and excellent water dispersity. It can be used as a versatile support for co-catalyst loading for photocatalytic dye degradation and water reduction. With 3.8 wt% Co3O4 loaded, PCNs can achieve more efficient photocatalytic degradation of Rhodamine B, compared with non-porous C3N4 nanosheets (CNs), bulk porous C3N4 (PCN) and bulk nonporous C3N4 (CN). With 1.0 wt% Pt loaded, CNs and PCN exhibit 7-8 times enhancement in H2 evolution than CN. Remarkably, PCNs with both porous and nanosheet-like features achieve 26 times higher activity in H2 evolution than CN. These significant improvements in photocatalytic activities can be attributed to the high surface area as well as better electron mobility of the two-dimensional nanostructure.Porous carbon nitride nanosheets (PCNs) have been prepared for the first time by a simple liquid exfoliation method via probe sonication. These mesoporous nanosheets of around 5 nm in thickness combine several advantages including high surface area, enhanced light absorption and excellent water dispersity. It can be used as a versatile support for co-catalyst loading for photocatalytic dye degradation and water reduction. With 3.8 wt% Co3O4 loaded, PCNs can achieve more efficient photocatalytic degradation of Rhodamine B, compared with non-porous C3N4 nanosheets (CNs), bulk porous C3N4 (PCN) and bulk nonporous C3N4 (CN). With 1.0 wt% Pt loaded, CNs and PCN exhibit 7-8 times enhancement in H2 evolution than CN. Remarkably, PCNs with both porous and nanosheet-like features achieve 26 times higher activity in H2 evolution than CN. These significant improvements in photocatalytic activities can be attributed to the high surface area as well as better electron mobility of the two-dimensional nanostructure. Electronic supplementary information (ESI) available: SEM, TEM and AFM images, BET isotherms and BJH pore size distribution of samples; effect of Co3O4 loading percentage on the RhB degradation; exfoliation studies of macroporous carbon nitride; table of literature studies on dye degradation by C3N4; comparison of probe sonication with bath sonication. See DOI: 10.1039/c4nr05341a

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. Photocatalytic and biocidal activities of novel coating systems of mesoporous and dense TiO?-anatase containing silver nanoparticles.

    PubMed

    Roldn, Mara V; de Oa, Paula; Castro, Yolanda; Durn, 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

  1. Metal dispersed activated carbon fibers and their application for removal of SO x

    NASA Astrophysics Data System (ADS)

    Hong, Ikpyo; Jiang, Hancheng; Park, Yang-Duk; Kim, Je-Young; Ha, Baik-Hyon

    2002-12-01

    Uniformly metal dispersed ACFs were prepared by mixing organometallic compounds with THF and pitch. The solvent was removed from this mixture and then pitch was spun, stabilized, carbonized and activated. The specific surface areas and pore size distributions of prepared ACFs and DeSO x catalytic reactivities were determined. The mesopores of ACF were developed by the addition of Co, Ni, Mn. The DeSO x catalytic reactivity of Ni, Pd, Co, V and Cr dispersed ACFs demonstrated much higher continuous reaction conversion than reference pitch-ACF.

  2. 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.

  3. 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

  4. Simultaneous Detection of Cadmium, Copper, and Lead using A Carbon Paste Electrode Modified with Carbamoylphosphonic Acid Self-Assembled Monolayer on Mesoporous Silica (SAMMS)

    SciTech Connect

    Yantasee, Wassana ); Lin, Yuehe ); Fryxell, Glen E.); Busche, Brad J.)

    2004-01-30

    A new sensor was developed for simultaneous detection of cadmium (Cd2+), copper (Cu2+), and lead (Pb2+), based on the voltammetric response at a carbon paste electrode modified with carbamoylphosphonic acid (acetamide phosphonic acid) self-assembled monolayer on mesoporous silica (Ac-Phos SAMMS). The adsorptive stripping voltammetry technique involves preconcentration of the metal ions onto Ac-Phos SAMMS under an open circuit, then electrolysis of the preconcentrated species, followed by a square wave potential sweep towards positive values. Factors affecting the preconcentration process were investigated. The voltammetric responses increased linearly with the preconcentration time from 1 to 30 minutes or with metal ion concentrations ranging from 10 to 200 ppb. The responses also evolved in the same fashion as adsorption isotherm in the pH range of 2-6. The metal detection limits were 10 ppb after 2 minutes preconcentration and improved to 0.5 ppb after 20 minutes preconcentration.

  5. 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).

  6. 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

  7. 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.

  8. Mesoporous nitrogen-doped carbon-glass ceramic cathodes for solid-state lithium-oxygen batteries.

    PubMed

    Kichambare, Padmakar; Rodrigues, Stanley; Kumar, Jitendra

    2012-01-01

    The composite of nitrogen-doped carbon (N-C) blend with lithium aluminum germanium phosphate (LAGP) was studied as cathode material in a solid-state lithium-oxygen cell. Composite electrodes exhibit high electrochemical activity toward oxygen reduction. Compared to the cell capacity of N-C blend cathode, N-C/LAGP composite cathode exhibits six times higher discharge cell capacity. A significant enhancement in cell capacity is attributed to higher electrocatalytic activity and fast lithium ion conduction ability of LAGP in the cathode. PMID:22148159

  9. Mesoporous titania thin films as efficient enzyme carriers for paraoxon determination/detoxification: effects of enzyme binding and pore hierarchy on the biocatalyst activity and reusability.

    PubMed

    Fran?i?, N; Bellino, M G; Soler-Illia, G J A A; Lobnik, A

    2014-06-21

    In this work we demonstrate the efficient immobilization of histidine 6-tagged organophosphate hydrolase (His6-OPH), an organophosphate-degrading enzyme, on mesoporous titania thin films. This permits the use of the biocatalyst films as efficient tools in the detection/detoxification of paraoxon. His6-OPH was immobilized on mesoporous thin films with uniform (9 nm) and bimodal (13-38 nm) pore size distribution, through covalent attachment and physical adsorption. The biocatalyst films show good activity, and enhanced stability with respect to the free enzyme at extreme conditions of pH and temperature, especially around neutral pH and room temperature. In addition, the bioactive films can be easily separated from the reaction media and reused multiple times without significant loss of activity. PMID:24791279

  10. A New Class of Highly Dispersed VOx Catalysts on Mesoporous Silica: Synthesis, Characterization, and Catalytic Activity in the Partial Oxidation of Ethanol

    SciTech Connect

    Kwak, Ja Hun; Herrera, Jose E.; Hu, Jian Zhi; Wang, Yong; Peden, Charles HF

    2006-01-26

    The morphology of vanadium oxide supported on a titania-modified mesoporous silica (MCM-41), obtained by means of a careful grafting process through atomic layer deposition, was studied using a variety of characterization techniques. The XRD together with TEM, 51V-NMR, Raman, FTIR and DRS-UV-Vis results showed that the vanadia species are extremely well dispersed onto the surface of the mesoporous support; the dispersion being stable upon thermal treatments up to 400 C. Studies of the catalytic activity of these materials were performed using the partial oxidation of ethanol as a probe reaction. The results indicate an intrinsic relationship between dispersion, the presence of a TiO2-VOx phase, and catalytic activity for oxidation and dehydration.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Textural and surface chemical characteristics of activated carbons prepared from cattle manure compost.

    PubMed

    Qian, Qingrong; Machida, Motoi; Tatsumoto, Hideki

    2008-01-01

    Two activated carbons (ACs) prepared from cattle manure compost (CMC) by ZnCl(2) activation were selected and out-gassed in a helium flow at various temperatures for 2h. The pore structure and surface chemical properties of the two selected ACs and their out-gassing treated ACs were characterized using N(2) adsorption-desorption, elements analysis, SEM and Boehm titration. A basic dye, methylene blue (MB), was chosen as an adsorbate to investigate the adsorption capacity for organic contaminant onto the activated carbons. It was found that the out-gassing treatment at 400 degrees C had little effect on the textural characteristics of the carbons but significantly changed the surface chemical properties such as surface functional groups concentration, pH and pH(PZC). The CMC-based activated carbons exhibited excellent performance for MB adsorption due to their high surface area, large mesopore volume and high nitrogen content. The kinetics of MB adsorption onto the activated carbons followed a pseudo-second-order equation, and the equilibrium data agreed well with the Langmuir model under the experimental conditions. The highest adsorption rate constant of k(ad) and the largest adsorption capacity of q(m) were found be 1.44x10(-4)g/mgmin and 519mg/g, respectively. The results suggested that the CMC-based activated carbons were effective adsorbents for the removal of methylene blue from aqueous solution. PMID:17553676

  16. Energy characteristics of adsorbed water in active carbons according to the NMR relaxation data

    NASA Astrophysics Data System (ADS)

    Gogelashvili, G. Sh.; Vartapetyan, R. Sh.; Ladychuk, D. V.; Khozina, E. V.; Grunin, Yu. B.

    2010-02-01

    Nuclear magnetic relaxation measurements were used to determine activation energy E act of the motion of water molecules adsorbed in active carbons. The E act value was found to depend on the filling of active carbon pores due to changes in the state of water molecules under adsorption. It was established that the E act = f( p/p s) plots, where p/p s is the relative pressure of water vapor observed for microporous active carbons (FAS-1, 2, N-15, SKT-6A), are similar in form to the corresponding plots of changes in water adsorption heats. In particular, we concluded that the plateau in the E act = f( p/p s) dependences, as in the case of adsorption heats, reflects the volumetric filling of active carbon micropores with water. We show that a linear function describes the increase in E act values for water upon the complete filling of micropores with an increase in the volume of adsorbed water clusters per one primary adsorption center ( W 0/ a m ). We establish that, for water in the FAS-3 sample, the deviation of E act values from this linear function was due to the contribution from the vapor phase in the mesopores ( x 0 = 0.7-1.2 nm) that make up a considerable part of the active carbons porous system.

  17. 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%.

  18. Activated carbon prepared from yerba mate used as a novel adsorbent for removal of tannery dye from aqueous solution.

    PubMed

    Linhares, Bruno; Weber, Caroline Trevisan; Foletto, Edson Luiz; Paz, Diego Silva; Mazutti, Marcio A; Collazzo, Gabriela Carvalho

    2013-01-01

    Activated carbon prepared from yerba mate (Ilex paraguariensis) was used as adsorbent for the removal of tannery dye from aqueous solution. The activated carbon was characterized, and it showed a mesoporous texture, with surface area of 537.4 m2 g(-1). The initial dye concentration, contact time and pH influenced the adsorption capacity. The equilibrium data were in good agreement with both Langmuir and Freundlich isotherms. The adsorption kinetics of the tannery dye on activated carbon prepared from yerba mate followed a pseudo-second-order model. The adsorption process was found to be controlled by both external mass-transfer and intraparticle diffusion, but the external diffusion was the dominating process. This work highlights the potential application of activated carbon produced from yerba mate in the field of adsorption. PMID:24350496

  19. 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

  20. 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

  1. 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.

  2. The effect of the distance between acidic site and basic site immobilized on mesoporous solid on the activity in catalyzing aldol condensation

    NASA Astrophysics Data System (ADS)

    Yu, Xiaofang; Yu, Xiaobo; Wu, Shujie; Liu, Bo; Liu, Heng; Guan, Jingqi; Kan, Qiubin

    2011-02-01

    Acid-base bifunctional heterogeneous catalysts containing carboxylic and amine groups, which were immobilized at defined distance from one another on the mesoporous solid were synthesized by immobilizing lysine onto carboxyl-SBA-15. The obtained materials were characterized by X-ray diffraction (XRD), N 2 adsorption, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron micrographs (SEM), transmission electron micrographs (TEM), elemental analysis, and back titration. Proximal-C-A-SBA-15 with a proximal acid-base distance was more active than maximum-C-A-SBA-15 with a maximum acid-base distance in aldol condensation reaction between acetone and various aldehydes. It appears that the distance between acidic site and basic site immobilized on mesoporous solid should be an essential factor for catalysis optimization.

  3. 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.

  4. 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

  5. Preparation of Mesoporous Bimetallic Au-Pt with a Phase-Segregated Heterostructure Using Mesoporous Silica.

    PubMed

    Kitahara, Masaki; Kubara, Saori; Takai, Azusa; Takimoto, Daisuke; Enomoto, Shinpei; Yamauchi, Yusuke; Sugimoto, Wataru; Kuroda, Kazuyuki

    2015-12-21

    Mesoporous bimetallic Au-Pt with a phase-segregated heterostructure has been prepared by using mesoporous silica SBA-15 as a template. Au nanoparticles were prepared as a seed metal within the mesopores, and subsequently Pt was deposited, sandwiching the Au seeds. Energy-dispersive X-ray (EDX) spectral mapping showed that the framework of mesoporous bimetallic Au-Pt, prepared by removing the silica template with HF, was composed of Au nanoparticles joined with Pt nanowires. The Au/Pt ratio of the mesoporous bimetallic Au-Pt could be varied by controlling the number of Au deposition cycles. Pre-adsorbed CO (COad ) stripping voltammetry of the mesoporous bimetallic Au-Pt showed that the surfaces of the joined bimetallic structure were electrochemically active. This could be attributed to the open framework structure having a high ratio of exposed bimetallic mesopore surfaces. The described preparative approach, involving a mesoporous silica template and stepwise deposition within the mesopores, enables control of the nanostructure of the bimetallic material, which is greatly promising for the further development of synthetic methodologies for bimetallic structures. PMID:26586355

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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 800C. 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

  11. 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.

  12. Textural mesoporosity and the catalytic activity of mesoporous molecular sieves with wormhole framework structures

    SciTech Connect

    Pauly, T.R.; Liu, Y.; Pinnavaia, T.J.; Billinge, S.J.L.; Rieker, T.P.

    1999-09-29

    Three different water-alcohol cosolvent systems were used to assemble mesoporous molecular sieve silicas with wormhole framework structures (previously denoted HMS silicas) from an electrically neutral amine surfactant (S{degree}) and a silicon alkoxide precursor (I{degree}). The fundamental particle size and associated textural (interparticle) porosity of the disordered structures were correlated with the solubility of the surfactant in the water-alcohol cosolvents used for the S{degree}I{degree} assembly process. Polar cosolvents containing relatively low volume fractions of C{sub n}H{sub 2n+1}OH alcohols (n = 1--3) gave heterogeneous surfactant emulsions that assembled intergrown aggregates of small primary particles with high textural pore volumes (designated HMS-HTx). Conversely, three-dimensional, monolithic particles with little or no textural porosity (designated HMS-LTx) were formed from homogeneous surfactant solutions in lower polarity cosolvents. Aluminum substituted AL-HMS-HTx analogues with high textural porosity and improved framework accessibility also were shown to be much more efficient catalysts than AL-HMS-LTx or monolithic forms of hexagonal AL-MCM-41 for the sterically demanding condensed phase alkylation of 2,4-di-tert-butylphenol with cinnamyl alcohol. Transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) studies verified the textural differences between wormhole HMS and electrostatically assembled hexagonal MCM-41 and SBA-3 molecular sieves. Power law fits to the scattering data indicated a surface fractal (D{sub s} = 2.76) for HMS-HTx, consistent with rough surfaces. A second power law at lower-q indicated the formation of a mass fractal (D{sub m} = 1.83) consistent with branching of small fundamental particles. Hexagonal MCM-41 and SBA-3 silicas, on the other hand, exhibited scattering properties consistent with moderately rough surfaces (D{sub s} = 2.35 and 2.22, respectively) and large particle diameters ({much{underscore}gt}1 {micro} m). HMS-LTx silicas showed little or no mass fractal character (D{sub m} = 2.87), and no surface fractal scattering.

  13. 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.

  14. Carboxylic acid-grafted mesoporous material and its high catalytic activity in one-pot three-component coupling reaction

    NASA Astrophysics Data System (ADS)

    Gomes, Ruth; Dutta, Saikat; Bhaumik, Asim

    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 employing powder XRD, solid st