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1

Preparation and characterization of mesoporous activated carbon from waste tires  

Microsoft Academic Search

Activated carbons were produced from waste tires and their characteristics were investigated. Rubber separated from waste tires was first carbonized at 500°C in N2 atmosphere. Next, the obtained chars were activated with steam at 850°C. As a result, fairly mesoporous activated carbons with mesopore volumes and BET surface areas up to 1.09 cm3\\/g and 737 m2\\/g, respectively, were obtained. To

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

2003-01-01

2

Nanoconfinement in activated mesoporous carbon of calcium borohydride for improved reversible hydrogen storage  

Microsoft Academic Search

Mesoporous carbon frameworks were synthesized using the soft-template method. Ca(BH4)2 was incorporated into activated mesoporous carbon by the incipient wetness method. The activation of mesoporous carbon was necessary to optimize the surface area and pore size. Thermal programmed absorption measurements showed that the confinement of this borohydride into carbon nanoscaffolds improved its reversible capacity (relative to the reactive portion) and

Cezar Com?nescu; Giovanni Capurso; Amedeo Maddalena

2012-01-01

3

Preparation of activated mesoporous carbons for electrosorption of ions from aqueous solutions  

SciTech Connect

Mesoporous carbon with a narrow pore size distribution centered at about 9 nm, which was prepared by self assembly of block copolymer and phloroglucinol-formaldehyde resin via the soft-template method, was activated by CO{sub 2} and potassium hydroxide (KOH). The effects of activation conditions, such as the temperature, activation time, and mass ratio of KOH/C, on the textural properties of the resulting activated mesoporous carbons were investigated. Activated mesoporous carbons exhibit high BET specific surface areas (up to {approx} 2000 m{sup 2} g{sup -1}) and large pore volumes (up to {approx} 1.6 cm{sup 3} g{sup -1}), but still maintain a highly mesoporous structure. Heat treatment of mesoporous carbons by CO{sub 2} generally requires a moderate to high extent of activation in order to increase its BET surface area by 2-3 times, while KOH activation needs a much smaller degree of activation than the former to reach an identical surface area, ensuring high yields of activated mesoporous carbons. In addition, KOH activation allows a controllable degree of activation by adjusting the mass ratio of KOH/C (2-8), as evidenced by the fact that surface area and pore volume increase with the mass ratio of KOH/C. The electrosorption properties of activated mesoporous carbons were investigated by cyclic voltammetry in 0.1 M NaCl aqueous solutions. Upon activation, the electrosorption capacitance of activated mesoporous carbons was greatly enhanced.

Dai, Sheng [ORNL; Lee, Jeseung [ORNL; Tsouris, Costas [ORNL; DePaoli, David W [ORNL; Wang, Xiqing [ORNL

2010-01-01

4

The influence of textural properties on the hydrogen adsorption on ordered mesoporous carbons and activated carbons  

Microsoft Academic Search

Microporosity is one of the key parameters which influences the physisorption of hydrogen on carbon materials. Ordered mesoporous carbons (OMC) which are synthetized by templating procedures have numerous interresting properties such as a large microporous volume, and a three dimensional mesoporous network. The aim of this study was to determine the hydrogen adsorption capacity for ordered mesoporous carbons and for

A. Didion; R. Gadiou; T. Piquero; P. David; C. Vix-Guterl

5

Preparation of mesoporous carbon by steam activation of commercial activated carbon in the presence of yttrium oxide  

Microsoft Academic Search

Mesoporous carbon was prepared by steam activation of commercial activated carbon in the presence of yttrium oxide. The loading of yttrium nitrate (precursor of yttrium oxide) was 0.2, 0.6, 1.0 and 2.0 wt%. The weight lost and gases formed during heating were detected by using thermogravimetric analysis and mass spectroscopy. The surface area and the total volume of the mesoporous

W. Z. Shen; J. T. Zheng; Y. L. Zhang; J. G. Wang; Z. F. Qin

2003-01-01

6

[Preparation, characterization and adsorption performance of mesoporous activated carbon with acidic groups].  

PubMed

Mesoporous activated carbons containing acidic groups were prepared with cotton stalk based fiber as raw materials and H3PO4 as activating agent by one step carbonization method. Effects of impregnation ratio, carbonization temperature and heat preservation time on the yield, elemental composition, oxygen-containing acid functional groups and adsorptive capacity of activated carbon were studied. The adsorption capacity of the prepared activated carbon AC-01 for p-nitroaniline and Pb(II) was studied, and the adsorption mechanism was also suggested according to the equilibrium experimental results. The maximum yield of activated carbons prepared from cotton stalk fiber reached 35.5% when the maximum mesoporous volume and BET surface area were 1.39 cm3 x g(-1) and 1 731 m2 x g(-1), respectively. The activated carbon AC-01 prepared under a H3 PO4/precursor ratio of 3:2 and activated at 900 degrees C for 90 min had a total pore volume of 1.02 cm3 x g(-1), a micoporous ratio of 31%, and a mesoporous ratio of 65%. The pore diameter of the mesoporous activated carbon was mainly distributed in the range of 2-5 nm. The Langmuir maximum adsorption capacities of Pb(II) and p-nitroaniline on cotton stalk fiber activated carbon were 123 mg x g(-1) and 427 mg x g(-1), respectively, which were both higher than those for commercial activated carbon fiber ACF-CK. The equilibrium adsorption experimental data showed that mesopore and oxygen-containing acid functional groups played an important role in the adsorption. PMID:23947073

Li, Kun-Quan; Li, Ye; Zheng, Zheng; Zhang, Yu-Xuan

2013-06-01

7

Nanoconfinement in activated mesoporous carbon of calcium borohydride for improved reversible hydrogen storage  

NASA Astrophysics Data System (ADS)

Mesoporous carbon frameworks were synthesized using the soft-template method. Ca(BH4)2 was incorporated into activated mesoporous carbon by the incipient wetness method. The activation of mesoporous carbon was necessary to optimize the surface area and pore size. Thermal programmed absorption measurements showed that the confinement of this borohydride into carbon nanoscaffolds improved its reversible capacity (relative to the reactive portion) and performance of hydrogen storage compared to unsupported borohydride. Hydrogen release from the supported hydride started at a temperature as low as 100?°C and the dehydrogenation rate was fast compared to the bulk borohydride. In addition, the hydrogen pressure necessary to regenerate the borohydride from the dehydrogenation products was reduced.

Com?nescu, Cezar; Capurso, Giovanni; Maddalena, Amedeo

2012-09-01

8

Nanoconfinement in activated mesoporous carbon of calcium borohydride for improved reversible hydrogen storage.  

PubMed

Mesoporous carbon frameworks were synthesized using the soft-template method. Ca(BH(4))(2) was incorporated into activated mesoporous carbon by the incipient wetness method. The activation of mesoporous carbon was necessary to optimize the surface area and pore size. Thermal programmed absorption measurements showed that the confinement of this borohydride into carbon nanoscaffolds improved its reversible capacity (relative to the reactive portion) and performance of hydrogen storage compared to unsupported borohydride. Hydrogen release from the supported hydride started at a temperature as low as 100 °C and the dehydrogenation rate was fast compared to the bulk borohydride. In addition, the hydrogen pressure necessary to regenerate the borohydride from the dehydrogenation products was reduced. PMID:22948563

Com?nescu, Cezar; Capurso, Giovanni; Maddalena, Amedeo

2012-09-05

9

KOH activation of ordered mesoporous carbons prepared by a soft-templating method and their enhanced electrochemical properties  

Microsoft Academic Search

Ordered mesoporous carbon (COU-2) was synthesized by a soft-templating method. The COU-2 mesoporous carbon was activated by using KOH to improve its porosity. The mesopore size of COU-2 was 5.5nm and did not change by the KOH activation. But, the BET surface area of COU-2 largely increased from 694 to 1685m2\\/g and total pore volume was increased from 0.54 to

Jin Jin; Shunsuke Tanaka; Yasuyuki Egashira; Norikazu Nishiyama

2010-01-01

10

Mesoporous carbon materials  

DOEpatents

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.

Dai, Sheng (Knoxville, TN); Wang, Xiqing (Oak Ridge, TN)

2012-02-14

11

Mesoporous carbon materials  

DOEpatents

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.

Dai, Sheng; Wang, Xiqing

2013-08-20

12

Dye adsorption on mesoporous activated carbon fiber obtained from pitch containing yttrium complex  

Microsoft Academic Search

The adsorption of acid dyes (Acid Blue 9, Acid Blue 74, Acid Orange 10, and Acid Orange 51), direct dyes (Direct Black 19, Direct Yellow 11, and Direct Yellow 50), and basic dyes (Basic Brown 1 and Basic Violet 3) on a highly mesoporous activated carbon fiber (Y-ACF) obtained from pitch containing yttrium acetylacetonate was investigated in terms of size

Hisashi Tamai; Takeshi Yoshida; Masahiko Sasaki

1999-01-01

13

Preparation of activated mesoporous carbons for electrosorption of ions from aqueous solutions  

Microsoft Academic Search

Mesoporous carbon with a narrow pore size distribution centered at about 9 nm, which was prepared by self assembly of block copolymer and phloroglucinol-formaldehyde resin via the soft-template method, was activated by COâ and potassium hydroxide (KOH). The effects of activation conditions, such as the temperature, activation time, and mass ratio of KOH\\/C, on the textural properties of the resulting

Sheng Dai; Jeseung Lee; Costas Tsouris; David W. DePaoli; Xiqing Wang

2010-01-01

14

Ammonia-Activated Mesoporous Carbon Membranes for Gas Separations  

SciTech Connect

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.

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

2011-01-01

15

N2 and H2 adsorption behavior of KOH-activated ordered mesoporous carbon  

NASA Astrophysics Data System (ADS)

Ordered mesoporous carbon, referred to as CMK-3, was synthesized by replication from SBA-15. Activated CMK-3 with developed pore structures provided a large surface area and higher hydrogen adsorption capacities after KOH activation at 1073-1223 K. To characterize the pore structure of the activated samples, N2 and H2 adsorption were measured at 77 K. The hydrogen adsorption of activated CMK-3 increased to 2.26 wt.% at an activation temperature of 1173 K due to the formation of micropores. Thus, KOH activation was not only one of the most effective methods for developing porosity, but also raised the hydrogen storage capacity of CMK-3.

Lee, Sang Moon; Lee, Soon Chang; Hong, Won G.; Kim, Hae Jin

2012-12-01

16

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

PubMed

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

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

2013-08-02

17

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  

Microsoft Academic Search

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,

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

2011-01-01

18

Enhanced electrochemical hydrogen storage capacity of activated mesoporous carbon materials containing nickel inclusions  

Microsoft Academic Search

Electrochemical properties of activated ordered mesoporous carbon (OMC) containing nickel inclusions are investigated using cyclic voltammetry and galvanostatic charge\\/discharge techniques. The hard-template-route prepared OMC is of structurally well-ordered two-dimensional hexagonal structure with a high specific surface area of 1896.95cm2g?1, a pore volume of 1.781cm3g?1 and a pore size of 5.1nm, respectively. It is shown that OMC\\/0.3Ni electrode displays the highest

Ningning Liu; Longwei Yin; Le Kang; Xinyu Zhao; Chengxiang Wang; Luyuan Zhang; Dong Xiang; Rui Gao; Yongxin Qi; Ning Lun

2010-01-01

19

Characterization of mesoporous carbon prepared from date stems by H3PO4 chemical activation  

NASA Astrophysics Data System (ADS)

The present work was focused on the determination of texture, morphology, crystanillity and oxygenated surface groups characteristics of an activated carbon prepared from date stems. Chemical activation of this precursor at different temperatures (450, 550 and 650 °C) was adopted using phosphoric acid as dehydrating agent at (2/1) impregnation ratio. Fourier transform infrared spectroscopy study was carried out to identify surface groups in date stems activated carbons. The microscopic structure was examined by nitrogen adsorption at 77 K. The interlayer spacing (d200 and d100), stack height (Lc), stack width (La) and effective dimension L of the turbostratic crystallites (microcrystallite) in the date stems activated carbons were estimated from X-ray diffraction data (XRD). Results yielded a surface area, SBET, and total pore volume of 682, 1455, 1319 m2/g and 0,343, 1,045 and 0.735 cm3/g, for the carbon prepared at 450, 550 and 650 °C, respectively. Scanning electron microscopy exhibits a highly developed porosity which is in good agreement with the porous texture derived from gas adsorption data and these results confirm that the activated carbon is dominated by network of slit-shaped mesopores morphology and in some cases by varied micropores morphologies.

Hadoun, H.; Sadaoui, Z.; Souami, N.; Sahel, D.; Toumert, I.

2013-09-01

20

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

PubMed

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

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

2013-09-23

21

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

PubMed Central

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.

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

22

Regeneration of mesoporous inorganic materials using ordered mesoporous carbon as the template  

Microsoft Academic Search

Regeneration of mesoporous inorganic materials from ordered mesoporous carbons has been successfully performed in the present work. A mesoporous silica SBA-15 are used as a template for the synthesis of the mesoporous carbon CMK-3. Subsequently, mesoporous inorganic replica materials can be obtained from the mesoporous carbon. This synthetic principle is very useful for the preparation of various kinds of the

Ji Man Kirn; Min Kang; Seung Hwan Yi; Jae Eui Yie; Sang Hoon Joo; Ryong Ryoo

2003-01-01

23

Highly Stable and Active Pt-Cu Oxygen Reduction Electrocatalysts Based on Mesoporous Graphitic Carbon Supports  

SciTech Connect

The activity of oxygen reduction catalysts for fuel cells often decreases markedly (30-70%) during potential cycling tests designed to accelerate catalyst degradation. Herein we achieved essentially no loss in electrochemical surface area and catalyst activity during potential cycling from 0.5 to 1.2 V for presynthesized Pt-Cu nanoparticles of controlled composition that were infused into highly graphitic disordered mesoporous carbons (DMC). The high stability is favored by the strong metal-support interactions and low tendency for carbon oxidation, which mitigates the mechanisms of degradation. Electrochemical dealloying transforms the composition from Pt{sub 20}Cu{sub 80} to Pt{sub 85}Cu{sub 15} with a strained Pt-rich shell, which exhibits an enhanced ORR activity of 0.46 A/mg{sub Pt}, >4 fold that of pure Pt catalysts. The high uniformity in particle size and composition both before and after dealloying, as a consequence of the presynthesis/infusion technique, is beneficial for elucidating the mechanism of catalyst activity and, ultimately, for designing more active catalysts.

Dai, Sheng [ORNL; Gupta, Gaurav [University of Texas, Austin; Kumar, Pavan [University of Texas, Austin; Wiggins-camacho, Jaclyn [University of Texas, Austin; Wang, Xiqing [ORNL; Swinnea, Steven [University of Texas, Austin; More, Karren Leslie [ORNL; Stevenson, Keith J [ORNL; Johnston, Keith [University of Texas, Austin

2009-01-01

24

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

PubMed

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

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

25

Mesoporous carbons and polymers  

DOEpatents

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.

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

2001-01-01

26

Direct synthesis of ordered mesoporous carbons.  

PubMed

Ordered mesoporous carbon materials have recently aroused great research interest because of their widespread applications in many areas such as adsorbents, catalysts and supports, gas storage hosts, and electrode materials. The direct synthesis strategy from organic-organic self-assembly involving the combination of polymerizable precursors and block copolymer templates is expected to be more flexible in preparing mesoporous carbons, compared with the traditional nanocasting strategy of complicated and high-cost procedures using mesoporous silica materials as the hard template. In this review, we present the fundamentals and recent advances related to the field of ordered mesoporous carbon materials from the direct synthesis strategy of block copolymer soft-templating, with a focus on their controllable preparation, modification and potential applications. Under the guidance of their formation mechanism, the preparation of ordered mesoporous carbons are discussed in detail by consulting different experimental conditions, including synthetic pathways, precursors, catalysts and templates. Both the mesopore size and morphology control are introduced. The potential applications of pure mesoporous carbons, nonmetallic- and metallic-modified mesoporous carbons, and some interpenetrating carbon-based composites are demonstrated. Furthermore, remarks on the challenges and perspectives of research directions are proposed for further development of the ordered mesoporous carbons (232 references). PMID:23132523

Ma, Tian-Yi; Liu, Lei; Yuan, Zhong-Yong

2012-11-07

27

Templated mesoporous carbons for supercapacitor application  

Microsoft Academic Search

Mesoporous carbons prepared by an inverse replica technique have been used as electrodes for electrochemical capacitors. Such well-sized carbons were prepared from mesostructured SBA-16 silica materials that served as templates whereas polyfurfuryl alcohol was the carbon precursor. Two highly mesoporous carbons characterized by 3 and 8nm average pore diameter were tested in various electrolytic solutions (acidic, alkaline and aprotic).It can

A. B. Fuertes; G. Lota; T. A. Centeno; E. Frackowiak

2005-01-01

28

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

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

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

2010-11-27

29

Immobilisation of Pseudomonas gessardii acidic lipase derived from beef tallow onto mesoporous activated carbon and its application on hydrolysis of olive oil  

Microsoft Academic Search

The study was carried out to immobilise the acidic lipase derived from Pseudomonas gessardii onto mesoporous activated carbon (MAC400) for the application of hydrolysis of olive oil. MAC400 was prepared from rice husk by the two stages process. P. gessardii was isolated from the beef tallow acclimatised soil. The acidic lipase (ALIP) was produced from a slaughterhouse waste, namely beef

K. Ramani; R. Boopathy; C. Vidya; L. John Kennedy; M. Velan; G. Sekaran

2010-01-01

30

Enhanced photocatalytic activity of mesoporous TiO2 aggregates by embedding carbon nanotubes as electron-transfer channel.  

PubMed

Mesoporous multiwalled carbon nanotubes/titanium dioxide (CNTs/TiO(2)) nanocomposites with low loading amounts (0-0.5 wt%) of CNTs embedded inside mesoporous TiO(2) aggregates has been prepared by a simple one-pot hydrothermal method using titanium sulfate as titanium source. The as-prepared CNTs/TiO(2) samples are carefully characterized, analyzed and discussed. In contrast to previous reports with high CNT loading, our results indicate that a low CNT loading slightly influences the textural properties (including crystallite size, degree of crystallinity, specific surface areas, and pore volume etc.) and UV-light absorption of the mesoporous TiO(2) aggregates. The SEM and TEM results demonstrate that the CNTs are mostly embedded in the mesoporous TiO(2) aggregates. Moreover, chemical bonds are formed at the interface between CNTs and TiO(2), which is confirmed by the Raman, IR and XPS analyses. Significantly, we point out that PL analysis in terms of intensity of PL signals seems to not be a reliable way to monitor the recombination rate in the CNTs/TiO(2) composite, due to the quenching effect of CNTs. Instead, the analysis of transient photocurrent responses is introduced, which definitely reflects CNTs as fast electron transfer channels in chemically-bonded CNTs/TiO(2) composites with low CNT loading. Notably, the positive synergy effects of CNTs and TiO(2) depend on both the CNT loading amount and the state of interfacial contacts. In our study, only these chemically bonded CNTs/TiO(2) nanocomposites with appropriate loading amounts (<0.1 wt%) favor the separation of photogenerated electron-hole pairs and decrease their recombination rate and thus display significantly enhanced photocatalytic activity for degrading acetone in air under UV irradiation, as compared with pristine TiO(2) counterparts and commercial P25 photocatalyst. In contrast, a high CNT loading (>0.1 wt%) results in a decrease in photocatalytic activity; a simple mechanical mixing of CNTs and TiO(2) without forming chemical bonds at the interface also results in inferior photocatalytic performance. PMID:21173966

Yu, Jiaguo; Ma, Tingting; Liu, Shengwei

2010-12-21

31

Preparation of High Surface Area Mesoporous Activated Carbon: Kinetics and Equilibrium Isotherm  

Microsoft Academic Search

Activated carbon prepared from palm shell by phosphoric acid impregnation, at significantly favorable experimental conditions is characterized for the porous nature and adsorption of methylene blue dye molecules. The activation is carried out using a 2-stage activation process with the activation in a self generated atmosphere. An activation temperature of 500 °C, with an activation time of 75 minutes using

W. C. Lim; C. Srinivasakannan; V. Doshi

2012-01-01

32

Development of micro-mesoporous carbons from several seed hulls under varying conditions of activation  

Microsoft Academic Search

Seed hulls (or coats) of peanut, soybean, cottonseed, lupine, broad beans, and sunflower seeds, were subjected to various treatments in order to get adsorbing carbons. Characterization of porosity was determined by N2\\/77K adsorption isotherms. Simple pyrolysis at 500°C yields low adsorbing carbons of meso-\\/macroporous character, whereas steam activation of these chars at 850°C enhances porosity, in micropores, to a limited

Badie S. Girgis; Ashraf M. Soliman; Nady A. Fathy

2011-01-01

33

Mesoporous Carbon Materials: Synthesis and Modification  

Microsoft Academic Search

Porous carbon materials are of interest in many applications because of their high surface area and physicochemical properties. Conventional syntheses can only produce randomly porous materials, with little control over the pore-size distributions, let alone mesostructures. Recent breakthroughs in the preparation of other porous materials have resulted in the development of methods for the preparation of mesoporous carbon materials with

Chengdu Liang; Zuojiang Li

2008-01-01

34

Carbon Nanotube Synthesis Using Mesoporous Silica Templates  

SciTech Connect

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.

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

2002-07-01

35

Enhancement of photocatalytic activity of mesoporous TiO 2 by using carbon nanotubes  

Microsoft Academic Search

Titanium dioxide\\/carbon nanotubes (TiO2\\/CNTs) composites were prepared with the aid of ultrasonic irradiation. Products of different TiO2:CNTs molar ratio were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) adsorption analysis, thermogravimetric and differential thermal analysis (TGA–DSC), photoluminescence (PL) and UV–vis spectroscopy measurements (UV–vis). The photocatalytic activity was evaluated by the degradation

Ying Yu; Jimmy C. Yu; Jia-Guo Yu; Yuk-Chun Kwok; Yan-Ke Che; Jin-Cai Zhao; Lu Ding; Wei-Kun Ge; Po-Keung Wong

2005-01-01

36

Inorganic–organic hybrid materials based on functionalized silica and carbon: A comprehensive understanding toward the structural property and catalytic activity difference over mesoporous silica and carbon supports  

Microsoft Academic Search

Inorganic–organic hybrid materials based on functionalized silica and carbon were synthesized by anchoring molybdovanadophosphoric acid (H5[PMo10V2O40]·32.5H2O) onto amine-functionalized SBA-15, ethane-bridged SBA-15 and mesoporous carbon, respectively. Small angle X-ray diffraction, N2 sorption analysis, HRTEM, SEM, FT-IR, CP-MAS NMR were used to diagnose the mesoporous structure of inorganic–organic hybrid materials. The structural integrity of molybdovanadophosphoric acid has been found to be retained

Ankur Bordoloi; Nevin T. Mathew; F. Lefebvre; S. B. Halligudi

2008-01-01

37

Cadmium(II) and lead(II) adsorption onto hetero-atom functional mesoporous silica and activated carbon  

NASA Astrophysics Data System (ADS)

Adsorption of cadmium(II) and lead(II) on amino-, mercapto-functionalized mesoporous silica (HMS) and carboxylic-functionalized activated carbon (AC) were examined. The resultant isotherms fitted the Langmuir model and amino-functionalized HMS exhibited the highest adsorption capacity for both cadmium(II) and lead(II). Adsorption affinities for cadmium(II) were always greater than those for lead(II) in all three adsorbent types, while the difference between the two values was the largest for mercapto-functionalized HMS indicating a selective adsorption of cadmium(II). Influence of equilibrium solution pH on adsorption of cadmium(II), lead(II) and their binary mixtures was also studied. Carboxylic-functionalized AC adsorbed cadmium(II) and lead(II) in a wide pH range than conditions for the mercapto-functionalized HMS. It was concluded that each functional group had its own characteristics and advantages for adsorption of heavy metal ions; amino-groups showed high adsorption capacity, while mercapto-groups had good selectivity toward cadmium(II) adsorption and a wide solution pH in adsorption by carboxylic-groups were established in this study.

Machida, Motoi; Fotoohi, Babak; Amamo, Yoshimasa; Mercier, Louis

2012-07-01

38

Exploratory study of mesopore templating with carbon during zeolite synthesis  

Microsoft Academic Search

Here we present an exploratory study on the generation of mesopores in zeolite crystals by templating with carbon during synthesis. With nitrogen physisorption, scanning electron microscopy and (three-dimensional) transmission electron microscopy we have studied the influence of the carbon source and zeolite synthesis conditions on the mesopores generated after the carbon has been burned off. In particular, silicalite-1 crystals have

A. H. Janssen; I. Schmidt; C. J. H. Jacobsen; A. J. Koster; K. P. de Jong

2003-01-01

39

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

SciTech Connect

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.

Yoon, Songhun, E-mail: yoonshun@krict.re.kr [Advanced Chemical Technology Division, Korea Research Institute of Chemical Technology (KRICT), Sinseongno 19, Yuseong, Daejeon 305-600 (Korea, Republic of); Oh, Seung M. [Research Center for Energy Conversion and Storage (RCECS), School of Chemical and Biological Engineering and Institute of Chemical Process, College of Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Lee, Chulwee [Advanced Chemical Technology Division, Korea Research Institute of Chemical Technology (KRICT), Sinseongno 19, Yuseong, Daejeon 305-600 (Korea, Republic of)

2009-08-05

40

Synthesis of mesoporous carbon and its adsorption property to biomolecules  

Microsoft Academic Search

Mesoporous carbon (MC) with high surface area and large pore volume was synthesized using mesophase pitch as a carbon precursor and nanosized MgO as an additive. The maximum surface area, largest pore volume and highest mesoporous ratio of as-prepared MC were up to 1400m2\\/g, 2.8cm3\\/g and 89%, respectively. The mesoporous structures (3–40nm) of MC were directly observed under SEM and

D. P. Xu; S.-H. Yoon; I. Mochida; W. M. Qiao; Y. G. Wang; L. C. Ling

2008-01-01

41

Adsorption of phenol from aqueous solutions using mesoporous carbon prepared by two-stage process  

Microsoft Academic Search

Porous carbon prepared from rice husk using phosphoric acid activation through precarbonization and chemical activation has been examined for the adsorption of phenol from aqueous solutions. The method adopted could produce carbons with micro and mesoporous structure. The surface area, pore volume and pore size distribution of carbon samples activated at three different temperatures 700, 800 and 900°C have been

L. John Kennedy; J. Judith Vijaya; K. Kayalvizhi; G. Sekaran

2007-01-01

42

Phosphorylated Mesoporous Carbon as a Solid Acid Catalyst  

SciTech Connect

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

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

2011-01-01

43

Three-dimensional micro/mesoporous carbon composites with carbon nanotube networks for capacitive deionization  

NASA Astrophysics Data System (ADS)

The three-dimensional micro/mesoporous carbon composites with carbon nanotube networks for capacitive deionization (CDI) were synthesized through an organic–inorganic self-assemble route with the subsequent activation by KOH. The crucial factors for the textural properties of composites were investigated. It was demonstrated that the new micropores emerge on the mesoporous framework of composites with suitable activation conditions, and some generated micropores also interconnect with others, which gives rise to the broaden pore size in the inner carbon channels and finally forms the efficient three-dimensional micro/mesoporous structure. In the meantime, the activation creates abundant defects on carbon nanotube networks, which also increase the surface area and ion diffusion channels. The electrochemical test shows that the activated composites exhibit the improved electrosorption capacitance. Through the inner resistance and energy density analyses, the activated composite electrode shows a slightly higher resistance but almost an approximate energy density as compared with the pristine one. Meanwhile, the activated composites are revealed to be more effective to adsorb ions in an aqueous solution under a lower CDI voltage, making it possible for the energy saving during CDI procedures. The results mentioned above prove that the activated composites are candidate electrode materials for CDI application, for its high surface area, suitable pore size/volume and special interconnected micro/mesoporous structure, superior electrochemical and CDI performances.

Peng, Zheng; Zhang, Dengsong; Yan, Tingting; Zhang, Jianping; Shi, Liyi

2013-10-01

44

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

SciTech Connect

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.

Fulvio, Pasquale F [ORNL; Dai, Sheng [ORNL; Guo, Bingkun [ORNL; Mahurin, Shannon Mark [ORNL; Mayes, Richard T [ORNL; Sun, Xiao-Guang [ORNL; Veith, Gabriel M [ORNL; Brown, Suree [ORNL; Adcock, Jamie [University of Tennessee, Knoxville (UTK)

2011-01-01

45

Using mesoporous carbon electrodes for brackish water desalination.  

PubMed

Electrosorptive deionisation is an alternative process to remove salt ions from the brackish water. The porous carbon materials are used as electrodes. When charged in low voltage electric fields, they possess a highly charged surface that induces adsorption of salt ions on the surface. This process is reversible, so the adsorbed salt ions can be desorbed and the electrode can be reused. In the study, an ordered mesoporous carbon (OMC) electrode was developed for electrosorptive desalination. The effects of pore arrangement pattern (ordered and random) and pore size distribution (mesopores and micropores) on the desalination performance was investigated by comparing OMC and activated carbon (AC). It were revealed from X-ray diffraction and N(2) sorption measurements that AC has both micropores and mesopores, whereas ordered mesopores are dominant in OMC. Their performance as potential electrodes to remove salt was evaluated by cyclic voltammetry (CV) and galvanostatic charge/discharge tests at a range of electrolyte concentrations and sweep rates. It is deduced that under the same electrochemical condition the specific capacitance values of OMC electrode (i.e. 133 F/g obtained from CV at a sweep rate of 1 mV/s in 0.1M NaCl solution) are larger than those of AC electrode (107 F/g), suggesting that the former has a higher desalting capacity than the latter. Furthermore, the OMC electrode shows a better rate capacity than the AC electrode. In addition, the desalination capacities were quantified by the batch-mode experiment at low voltage of 1.2V in 25 ppm NaCl solution (50 micros/cm conductivity). It was found that the adsorbed ion amounts of OMC and AC electrodes were 11.6 and 4.3 micromol/g, respectively. The excellent electrosorptive desalination performance of OMC electrode might be not only due to the suitable pore size (average of 3.3 nm) for the propagation of the salt ions, but also due to the ordered mesoporous structure that facilitates desorption of the salt. Based on the results, it was found that the development of an ordered mesoporous structure and the control of the number of micropores are two important strategies for optimising electrode material properties for electrosorptive deionisation. PMID:18222527

Zou, Linda; Li, Lixia; Song, Huaihe; Morris, Gayle

2008-01-04

46

Formation of graphite-derived layered mesoporous carbon materials  

Microsoft Academic Search

A novel layered mesoporous carbon (LMC) material with structural peculiarity can be obtained by leaching silica components from the high temperature treatment products of degraded graphite layers and silica nanocomposites soft-chemically synthesized from graphite precursor. Nitrogen adsorption indicates that LMC exhibits a high mesopore specific surface area with only mesoporosity of narrow pore size distribution. Structural analysis shows a crystalline

Z.-M. Wang; K. Hoshinoo; M. Yamagishi; N. Yoshizawa; H. Kanoh; T. Hirotsu

2006-01-01

47

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

PubMed

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

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

2005-03-16

48

Graphitic mesoporous carbon as a durable fuel cell catalyst support  

Microsoft Academic Search

Highly stable graphitic mesoporous carbons (GMPCs) are synthesized by heat-treating polymer-templated mesoporous carbon (MPC) at 2600°C. The electrochemical durability of GMPC as Pt catalyst support (Pt\\/GMPC) is compared with that of carbon black (Pt\\/XC-72). Comparisons are made using potentiostatic and cyclic voltammetric techniques on the respective specimens under conditions simulating the cathode environment of PEMFC (proton exchange membrane fuel cell).

Paul V. Shanahan; Lianbin Xu; Chengdu Liang; Mahesh Waje; Sheng Dai; Y. S. Yan

2008-01-01

49

Electrochemical performance of a novel ionic liquid derived mesoporous carbon.  

PubMed

A novel nano-fibrillated mesoporous carbon (IFMC) was found to be an effective modifier in combination with ionic liquid 1-octylpyridinum hexafluorophosphate (OPFP) as a binder to give impregnated graphite electrodes with outstanding electrochemical performances. PMID:22314280

Karimi, Babak; Behzadnia, Hesam; Rafiee, Mohammad; Vali, Hojatollah

2012-02-07

50

Mesoporous carbon incorporated metal oxide nanomaterials as supercapacitor electrodes.  

PubMed

Supercapacitors have attracted huge attention in recent years as they have the potential to satisfy the demand of both huge energy and power density in many advanced technologies. However, poor conductivity and cycling stability remains to be the major challenge for its widespread application. Various strategies have been developed for meeting the ever-increasing energy and power demands in supercapacitors. This Research News article aims to review recent progress in the development of mesoporous carbon incorporated metal oxide nanomaterials, especially metal oxide nanoparticles confined in ordered mesoporous carbon and 1D metal oxides coated with a layer of mesoporous carbon for high-performance supercapacitor applications. In addition, a recent trend in supercapacitor development - hierarchical porous graphitic carbons (HPGC) combining macroporous cores, mesoporous walls, and micropores as an excellent support for metal oxides - is also discussed. PMID:23030034

Jiang, Hao; Ma, Jan; Li, Chunzhong

2012-08-01

51

Mesoporous carbon for capacitive deionization of saline water.  

PubMed

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

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

2011-11-07

52

Low temperature preparation and visible light photocatalytic activity of mesoporous carbon-doped crystalline TiO 2  

Microsoft Academic Search

A visible-light-active TiO2 photocatalyst was prepared through carbon doping by using glucose as carbon source. Different from the previous carbon-doped TiO2 prepared at high temperature, our preparation was performed by a hydrothermal method at temperature as low as 160°C. The resulting photocatalyst was characterized by XRD, XPS, TEM, nitrogen adsorption, and UV–vis diffuse reflectance spectroscopy. The characterizations found that the

Wenjie Ren; Zhihui Ai; Falong Jia; Lizhi Zhang; Xiaoxing Fan; Zhigang Zou

2007-01-01

53

Structured carbon adsorbents from clay, zeolite and mesoporous aluminosilicate templates  

Microsoft Academic Search

Porous carbons templated from inorganic materials such as zeolites and mesoporous molecular sieves received considerable attention in the last decade. In this context, we discuss the effects of different templating structures on the carbons yielded. We describe templating using a commercial cationic clay (Wyoming bentonite), a commercial zeolite (Tosoh H-Beta) and a synthetic mesoporous aluminosilicate (Al-MCM-48), as exemplars of the

P. M Barata-Rodrigues; T. J Mays; G. D Moggridge

2003-01-01

54

Adsorption of alkaloids on ordered mesoporous carbon.  

PubMed

An ordered mesoporous carbon (OMC) adsorbent was synthesized, characterized, and evaluated for effective separation and purification of alkaloid compounds from aqueous solutions. The OMC adsorbent has a large BET specific surface area (1532.2m(2)/g), large pore volume (2.13cm(3)/g), and narrow pore diameter distribution with a median pore diameter of 4.21nm. Berberine hydrochloride, colchicine, and matrine were selected as the model compounds for evaluating the adsorption properties of the OMC adsorbent for alkaloid purification. Batch adsorption experiments of pure components in water were carried out to measure both adsorption equilibria and kinetics, and column breakthrough and desorption experiments were performed to validate the separation and regeneration efficacy of the OMC adsorbent. The adsorption equilibrium capacities of berberine hydrochloride, colchicine, and matrine on the OMC adsorbent at 0.100mg/L and 298K are 450, 600, and 480mg/g, respectively, which are more than double the adsorption capacities of these compounds on two commonly used commercial resins (HPD300 and HPD100B) at similar conditions. Adsorption equilibrium of all three alkaloids could be obtained within 120min at 298K. The dynamic adsorption capacities determined from the breakthrough experiments are within 12% of the estimated equilibrium capacities from the Langmuir isotherms; and 74.3-92.8% of the adsorbed amounts could be recovered by desorbing with a 70% alcohol solution. The adsorption isotherms are analyzed with both Langmuir and Freundlich models, the adsorption kinetic data with the pseudo-first-order and pseudo-second-order models, and the breakthrough curves with four breakthrough models. The large adsorption capacity, fast adsorption rate, and easy regeneration make the ordered mesoporous carbon a promising adsorbent for adsorption and purification of alkaloid compounds from the extracts of herbal plants. PMID:23953651

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

2013-07-29

55

Micro\\/mesoporous conducting carbonized polyaniline 5-sulfosalicylate nanorods\\/nanotubes: Synthesis, characterization and electrocatalysis  

Microsoft Academic Search

Micro\\/mesoporous conducting nitrogen-containing carbon nanorods\\/nanotubes with high surface area, and excellent electrocatalytic activity for the oxygen reduction reaction, were synthesized by the carbonization of self-assembled polyaniline (PANI) 5-sulfosalicylate nanorods\\/nanotubes. Carbonization was carried out by means of gradual heating in a nitrogen atmosphere up to 800°C. The morphology of the PANI 5-sulfosalicylate was preserved after carbonization. Carbonized PANI nanostructures containing ?10wt%

Aleksandra Janoševi?; Igor Pašti; Nemanja Gavrilov; Slavko Mentus; Gordana ?iri?-Marjanovi?; Jugoslav Krsti?; Jaroslav Stejskal

2011-01-01

56

Sustainable mesoporous carbons as storage and controlled-delivery media for functional molecules.  

PubMed

Here, we report the synthesis of surfactant-templated mesoporous carbons from lignin, which is a biomass-derived polymeric precursor, and their potential use as a controlled-release medium for functional molecules such as pharmaceuticals. To the best of our knowledge, this is the first report on the use of lignin for chemical-activation-free synthesis of functional mesoporous carbon. The synthesized carbons possess the pore widths within the range of 2.5-12.0 nm. In this series of mesoporous carbons, our best result demonstrates a Brunauer-Emmett-Teller (BET) surface area of 418 m(2)/g and a mesopore volume of 0.34 cm(3)/g, which is twice the micropore volume in this carbon. Because of the dominant mesoporosity, this engineered carbon demonstrates adsorption and controlled release of a representative pharmaceutical drug, captopril, in simulated gastric fluid. Large-scale utilization of these sustainable mesoporous carbons in applications involving adsorption, transport, and controlled release of functional molecules is desired for industrial processes that yield lignin as a coproduct. PMID:23731336

Saha, Dipendu; Payzant, E Andrew; Kumbhar, Amar S; Naskar, Amit K

2013-06-17

57

Carbon dioxide capture using polyethylenimine-loaded mesoporous carbons.  

PubMed

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

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

2013-01-01

58

Effect of silver nanoparticles deposited on micro\\/mesoporous activated carbons on retention of NO x at room temperature  

Microsoft Academic Search

Wood-based activated carbon was modified by deposition of silver using Tollens method. Adsorbents with various contents of silver were used to study NO2 and NO (the product of NO2 reduction by carbon) retention. The surface of the initial and exhausted materials was characterized using adsorption of nitrogen, XRD, SEM\\/EDX, FTIR and TA. The results indicated that with an increasing content

Svetlana Bashkova; Deeona Deoki; Teresa J. Bandosz

2011-01-01

59

Analysis of Various Experimental Methods and Preparation of Mesoporous Activated Carbon Powders from Sawdust Using Phosphoric Acid  

Microsoft Academic Search

A critical analysis of various reported experimental methods utilized for preparation of activated carbon using phosphoric acid was attempted to identify the right choice of experimental method. The various experimental methods were grouped into three major categories; of these, a two-stage activation process with the precursor exposed to preset furnace temperature in a self-generated atmosphere was identified to be a

C. Srinivasakannan; N. Balasubramaniam

2007-01-01

60

Well-crystallized mesoporous TiO2 shells for enhanced photocatalytic activity: prepared by carbon coating and silica-protected calcination.  

PubMed

Mesoporous anatase-phase TiO2 hollow shells were successfully fabricated by the solvothermal and calcination process. This method involves preparation of SiO2@TiO2 core-shell colloidal templates, sequential deposition of carbon and then silica layers through solvothermal and sol-gel processes, crystallization of TiO2 by calcination and finally removal of the inner and outer silica to produce hollow anatase TiO2 shells. The prepared samples were characterized by transmission electron microscopy, X-ray diffraction, N2 adsorption-desorption isotherms and UV-vis absorption spectroscopy. The results show that a uniform carbon layer is coated on the core-shell particles through the solvothermal process. The combustion of carbon offers the space for the TiO2 to further grow into large crystal grains, and the outer silica layer serves as a barrier against the excessive growth of anatase TiO2 nanocrystals. Furthermore, the initial crystallization of TiO2 generated in the carbon coating step and the heat generated by the combustion of the carbon layer allow the crystallization of TiO2 at a relatively low temperature without changing the uniform structure. When used as photocatalysts for the oxidation decomposition of Rhodamine B in aqueous solution under UV irradiation, the hollow TiO2 shells showed enhanced catalytic activity. Moreover, the TiO2 hollow shells prepared with optimal crystallinity by this method showed a higher performance than commercial P25 TiO2. PMID:23389414

Zhang, Zewu; Zhou, Yuming; Zhang, Yiwei; Zhou, Shijian; Shi, Junjun; Kong, Jie; Zhang, Sicheng

2013-04-14

61

Mesoporous Carbon-based Materials for Alternative Energy Applications  

NASA Astrophysics Data System (ADS)

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.

Cross, Kimberly Michelle

62

Hierarchically porous nickel hydroxide\\/mesoporous carbon composite materials for electrochemical capacitors  

Microsoft Academic Search

Hierarchically porous composite materials consisting of nanoflake-like nickel hydroxide and mesoporous carbon are synthesized by a facile chemical precipitation method. The effects of microstructure and morphology of the carbon support on the electrochemical properties of the composite are also investigated. Structural characterizations have revealed that nanometer-sized nickel hydroxide nanoflakes can grow on the surface of mesoporous carbon supports. The mesoporous

Jing Zhang; Ling-Bin Kong; Jian-Jun Cai; Heng Li; Yong-Chun Luo; Long Kang

2010-01-01

63

Incorporation of platinum nanoparticles in ordered mesoporous carbon  

Microsoft Academic Search

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

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

2007-01-01

64

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

PubMed

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

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

2013-09-24

65

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

66

Enhanced hydrogen adsorption in ordered mesoporous carbon through clathrate formation  

Microsoft Academic Search

Ordered mesoporous carbons were synthesized with a soft-template approach and modified with a water and tetrahydrofuran mixture having a H2O\\/THF molar ratio of 17:1 as potential adsorbent media for hydrogen storage. Hydrogen adsorption equilibrium on the carbon adsorbents was measured gravimetrically at 270K and hydrogen pressures up to 163bar. Enhanced hydrogen adsorption was observed on the carbon adsorbents doped with

Dipendu Saha; Shuguang Deng

2009-01-01

67

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

SciTech Connect

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

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

2011-01-01

68

Incorporation of platinum nanoparticles in ordered mesoporous carbon.  

PubMed

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

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

2006-10-05

69

Controlled synthesis of mesoporous carbon nanostructures via a "silica-assisted" strategy.  

PubMed

We have established a facile and generalizable "silica-assisted" synthesis for diverse carbon spheres-a category that covers mesoporous carbon nanospheres, hollow mesoporous carbon nanospheres, and yolk-shell mesoporous carbon nanospheres-by using phenolic resols as a polymer precursor, silicate oligomers as an inorganic precursor, and hexadecyl trimethylammoniumchloride as a template. The particle sizes of the carbon nanospheres are uniform and easily controlled in a wide range of 180-850 nm by simply varying the ethanol concentrations. All three types of mesoporous carbon nanospheres have high surface areas and large pore volumes and exhibit promising properties for supercapacitors with high capacitance and favorable capacitance retention. PMID:23256449

Qiao, Zhen-An; Guo, Bingkun; Binder, Andrew J; Chen, Jihua; Veith, Gabriel M; Dai, Sheng

2012-12-24

70

Mesoporous silica nanoparticles for active corrosion protection.  

PubMed

This work presents the synthesis of monodisperse, mesoporous silica nanoparticles and their application as nanocontainers loaded with corrosion inhibitor (1H-benzotriazole (BTA)) and embedded in hybrid SiOx/ZrOx sol-gel coating for the corrosion protection of aluminum alloy. The developed porous system of mechanically stable silica nanoparticles exhibits high surface area (?1000 m2·g(-1)), narrow pore size distribution (d?3 nm), and large pore volume (?1 mL·g(-1)). As a result, a sufficiently high uptake and storage of the corrosion inhibitor in the mesoporous nanocontainers was achieved. The successful embedding and homogeneous distribution of the BTA-loaded monodisperse silica nanocontainers in the passive anticorrosive SiOx/ZrOx film improve the wet corrosion resistance of the aluminum alloy AA2024 in 0.1 M sodium chloride solution. The enhanced corrosion protection of this newly developed active system in comparison to the passive sol-gel coating was observed during a simulated corrosion process by the scanning vibrating electrode technique (SVET). These results, as well as the controlled pH-dependent release of BTA from the mesoporous silica nanocontainers without additional polyelectrolyte shell, suggest an inhibitor release triggered by the corrosion process leading to a self-healing effect. PMID:21344888

Borisova, Dimitriya; Möhwald, Helmuth; Shchukin, Dmitry G

2011-02-23

71

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

PubMed

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

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

2013-10-22

72

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

SciTech Connect

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.

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

2012-01-01

73

Preparation and functionalization of mesoporous silica, carbon and silica/carbon nanocomposites  

NASA Astrophysics Data System (ADS)

The synthesis of mesostructured materials including mesoporous silica, carbon and carbon-silica nanocomposites has become one of the leading topics in materials science because the mesostructured materials carry many unique properties such as high surface area, large and controllable pore size and structures, uniform pore size distributions and large pore volumes, which make the mesoporous materials many potential applications, for example catalyst supports, adsorbent for large molecules, hydrogen adsorption media, etc. Template synthesis, a unique approach that utilizes hard (preformed nanostructured inorganic frameworks or nanoparticles) and/or soft templates (liquid crystal phase of amphiphilic molecules) to organize precursor building blocks into large controllable structures, has emerged as the most promising method to fabricate mesostructured materials. Besides the mesostructure control, functionalization of mesoporous materials has also been a focus, because the functionalized organic groups may provide mesoporous materials with improved surface properties. This dissertation addresses the synthesis of mesoporous materials through template techniques including aerosol-assisted self-assembly and evaporation induced self-assembly methods. The functionalized mesoporous silica can be prepared by one-step co-condensation of TEOS and organosiline and co-assembly with amphiphilic molecular template. The mesostructure, pore size and morphology control can be realized by using different templates, synthesis methods and synthesis conditions. The content of hydrophobic molecule in the precursor solution also has dramatic effect on the mesostructures of obtained mesoporous silica particles. Both hard and soft templates are used to synthesize mesoporous carbon and carbon-based nanocomposites with tunable pore size, structures and morphologies. The applications of obtained mesoporous materials, such as catalysis and adsorption are discussed.

Hu, Qingyuan

74

Bimetallic ruthenium-copper nanoparticles embedded in mesoporous carbon as an effective hydrogenation catalyst.  

PubMed

Bimetallic ruthenium-copper nanoparticles embedded in the pore walls of mesoporous carbon were prepared via a template route and evaluated in terms of catalytic properties in d-glucose hydrogenation. The existence of bimetallic entities was supported by Ru L3-edge and Cu K-edge X-ray absorption results. The hydrogen spillover effect of the bimetallic catalyst on the hydrogenation reaction was evidenced by the results of both hydrogen and carbon monoxide chemisorptions. The bimetallic catalyst displayed a higher catalytic activity than the single-metal catalysts prepared using the same approach, namely ruthenium or copper nanoparticles embedded in the pore walls of mesoporous carbon. This improvement was due to the changes in the geometric and electronic structures of the bimetallic catalyst because of the presence of the second metal. PMID:24072134

Liu, Jiajia; Zhang, Li Li; Zhang, Jiatao; Liu, Tao; Zhao, X S

2013-09-26

75

Hydrogen uptake efficiency of mesoporous carbon nanofiber and its structural factors to determine the uptake efficiency  

Microsoft Academic Search

In this work, mesoporous carbon nanofibers (MCNF) were synthesized by using a template of mesoporous silicate nanofibers within anodic aluminum oxide (AAO) film and furfuryl alcohol for the carbon source at the carbonization temperatures (600, 900, and 1200°C). Due to the easy control nature of pore size and thickness of AAO film, the diameter and length of MCNF can easily

Ji-Eun Im; Seung-Lim Oh; Kyong-Hoon Choi; Kang-Kyun Wang; Soyoung Jung; Won Cho; Moonhyun Oh; Yong-Rok Kim

2010-01-01

76

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

SciTech Connect

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.

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

77

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

Microsoft Academic Search

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

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

2010-01-01

78

Synthesis of white light emitting mesoporous carbon-silica nanocomposite  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

79

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

SciTech Connect

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.

Wang, Xiqing [ORNL; Dai, Sheng [ORNL; Engelhard, Mark H [Pacific Northwest National Laboratory (PNNL); Wang, Congmin [ORNL; Liu, Jun [Pacific Northwest National Laboratory (PNNL); YANG, ZHENGUO [Pacific Northwest National Laboratory (PNNL); Lin, Yuehe [ORNL; Shao, Yuyan [Pacific Northwest National Laboratory (PNNL)

2010-01-01

80

Direct Electrochemistry and Electrocatalysis of Hemoglobin at Mesoporous Carbon Modified Electrode  

PubMed Central

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

Pei, Supeng; Qu, Song; Zhang, Yongming

2010-01-01

81

Sulfonated mesoporous silica-carbon composites and their use as solid acid catalysts  

NASA Astrophysics Data System (ADS)

The synthesis of highly functionalized porous silica-carbon composites made up of sulfonic groups attached to a carbon layer coating the pores of three types of mesostructured silica (i.e. SBA-15, KIT-6 and mesocellular silica) is presented. The synthesis procedure involves the following steps: (a) removal of the surfactant, (b) impregnation of the silica pores with a carbon precursor, (c) carbonization and (d) sulfonation. The resulting silica-carbon composites contain ˜30 wt % of carbonaceous matter with a high density of acidic groups attached to the deposited carbon (i.e.sbnd SO3H, sbnd COOH and sbnd OH). The structural characteristics of the parent silica are retained in the composite materials, which exhibit a high surface area, a large pore volume and a well-ordered porosity made up uniform mesopores. The high density of the sulfonic groups in combination with the mesoporous structure of the composites ensures that a large number of active sites are easily accessible to reactants. These sulfonated silica-carbon composites behave as eco-friendly, active, selective, water tolerant and recyclable solid acids. In this study we demonstrate the usefulness of these composites as solid acid catalysts for the esterification of maleic anhydride, succinic acid and oleic acid with ethanol. These composites exhibit a superior intrinsic catalytic activity to other commercial solid acids such as Amberlyst-15.

Valle-Vigón, Patricia; Sevilla, Marta; Fuertes, Antonio B.

2012-11-01

82

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

SciTech Connect

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.

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

2012-01-01

83

Platinum catalyst on ordered mesoporous carbon with controlled morphology for methanol electrochemical oxidation  

NASA Astrophysics Data System (ADS)

Ordered mesoporous carbons CMK-3 with various morphologies are synthesized by using various mesoporous silica SBA-15 as template and then support to prepare Pt/CMK-3 catalyst. The obtained catalysts are compared in terms of the electrocatalytic activity for methanol oxidation in sulfuric acidic solutions. The structure characterizations and electrochemical analysis reveal that Pt catalysts with the CMK-3 support of large particle size and long channel lengths possess larger electrochemical active surface area (ECSA) and higher activity toward methanol oxidation than those with the other two supports. The better performance of Pt/CMK-3 catalyst may be due to the larger area of electrode/electrolyte interface and larger ECSA value of Pt catalyst, which will provide better structure in favor of the mass transport and the electron transport.

Kong, Ling-Bin; Li, Heng; Zhang, Jing; Luo, Yong-Chun; Kang, Long

2010-09-01

84

Active carbon catalyst for heavy oil upgrading  

Microsoft Academic Search

The active carbon (AC) catalyst was studied by hydrocracking of Middle Eastern vacuum residue (VR) for heavy oil upgrading. It was observed that the active carbon has the affinity to heavy hydrocarbon compounds and adsorption selectivity to asphaltenes, and exhibits better ability to restrict the coke formation during the hydrocracking reaction of VR. The mesopore of active carbon was thought

Hidetsugu Fukuyama; Satoshi Terai; Masayuki Uchida; José L. Cano; Jorge Ancheyta

2004-01-01

85

A simple method to ordered mesoporous carbons containing nickel nanoparticles  

SciTech Connect

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.

Dai, Sheng [ORNL; Wang, Xiqing [ORNL

2009-01-01

86

Platinum and platinum–ruthenium nanoparticles supported on ordered mesoporous carbon and their electrocatalytic performance for fuel cell reactions  

Microsoft Academic Search

Highly ordered meso-porous carbon, denoted CMK-3 was synthesized by using mesoporous silicates, SBA-15 as the starting templating materials. The ordered mesoporous carbon was loaded with platinum and platinum–ruthenium nanoparticles using alternative synthesis techniques. The metal loaded ordered mesoporous carbon powders were characterized by transmission electron microscopy (HRTEM), energy dispersive X-ray analysis (EDX), X-ray diffraction, and nitrogen adsorption isotherm experiments. Micrometer-scale

Jie Ding; Kwong-Yu Chan; Jiawen Ren; Feng-shou Xiao

2005-01-01

87

Mesoporous carbon nanofibers with a high surface area electrospun from thermoplastic polyvinylpyrrolidone  

NASA Astrophysics Data System (ADS)

Carbon nanofibers (CNFs) have been synthesized from thermoplastic polyvinylpyrrolidone (PVP) using electrospinning in combination with a novel three-step heat treatment process, which successfully stabilizes the fibrous morphology before carbonization that was proven to be difficult for thermoplastic polymers other than polyacrylonitrile (PAN). These CNFs are both mesoporous and microporous with high surface areas without subsequent activation, and thus overcome the limitations of PAN based CNFs, and are processed in an environmentally friendly and more cost effective manner. The effects of heat treatment parameters and precursor concentration on the morphologies and porous properties of CNFs have been investigated, and their application as anodes for lithium ion batteries has also been demonstrated.

Wang, Peiqi; Zhang, Dan; Ma, Feiyue; Ou, Yun; Chen, Qian Nataly; Xie, Shuhong; Li, Jiangyu

2012-10-01

88

Nanoconfinement induced formation of core/shell structured mesoporous carbon spheres coated with solid carbon shell.  

PubMed

A novel method for the fabrication of core/shell structured mesoporous carbon spheres with solid shell using a template method has been presented. The unique molecular nanostructures are characterized by XRD, TEM, TGA, and nitrogen adsorption/desorption measurement. The formation mechanism of the mesostructured carbon spheres with a carbon shell is proposed according to the experimental results. Nanoconfinement effect, occurring in the core/shell structured template, is believed to play a key role in mediating the formation of these hierarchical carbon mesostructures, with SnO2 as a template and C2H4 as a carbon source of a mesoporous carbon core. This synthesis method is simple, straightforward, and suitable for the preparation of various nanostructures that are unique scaffolds in catalytic and electrochemical applications. PMID:23560552

Wenelska, Karolina; Kierzek, Krzysztof; Kale?czuk, Ryszard J; Chen, Xuecheng; Mijowska, Ewa

2013-04-05

89

Preparation of mesoporous activated carbon from palm-date pits: optimization study on removal of bentazon, carbofuran, and 2,4-D using response surface methodology.  

PubMed

Palm-date pits were used to prepare activated carbon by physiochemical activation method, which consisted of potassium hydroxide (KOH) treatment and carbon dioxide (CO2) gasification. The effects of variable parameters, activation temperature, activation time and chemical impregnation ratios (KOH: char by weight) on the preparation of activated carbon and for removal of pesticides: bentazon, carbofuran and 2,4-dichlorophenoxyacetic acid (2,4-D) were investigated. Based on the central composite design (CCD), two factor interaction (2FI) and quadratic models were respectively employed to correlate the effect of variable parameters on the preparation of activated carbon used for removal of pesticides with carbon yield. From the analysis of variance (ANOVA), the most influential factor on each experimental design response was identified. The optimum conditions for preparing activated carbon from palm-date pits were found to be: activation temperature of 850 °C, activation time of 3 h and chemical impregnation ratio of 3.75, which resulted in an activated carbon yield of 19.5% and bentazon, carbofuran, and 2,4-D removal of 84, 83, and 93%, respectively. PMID:24135098

Salman, J M; Abid, F M

2013-01-01

90

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

SciTech Connect

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

Villa, Alberto [Universita di Milano, Italy; Schiavoni, Marco [University of Milan and INFN, Milano, Italy; Fulvio, Pasquale F [ORNL; Mahurin, Shannon Mark [ORNL; Dai, Sheng [ORNL; Mayes, Richard T [ORNL; Veith, Gabriel M [ORNL; Prati, Laura [Universita di Milano, Italy

2013-01-01

91

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

PubMed

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

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

2013-05-21

92

Facile preparation of ordered mesoporous silica-carbon composite nanoparticles for glycan enrichment.  

PubMed

Silica-carbon composite nanoparticles (NP-MCM-C) with uniform shapes and highly ordered mesoporous structures are directly prepared by using template polymers as the carbon source. And, taking advantage of the size exclusion effect of the mesopores to proteins and the specific interaction between carbon and oligosaccharides, the prepared nanoparticles are utilized to enrich N-linked glycans from complex biological samples with high selectivity and efficiency. PMID:23628764

Qin, Hongqiang; Hu, Zhengyan; Wang, Fangjun; Zhang, Yi; Zhao, Liang; Xu, Guiju; Wu, Ren'an; Zou, Hanfa

2013-06-01

93

Preparation and characterization of mesoporous carbons using a Turkish natural zeolitic template\\/furfuryl alcohol system  

Microsoft Academic Search

The template carbonization method was utilized for the production of mesoporous carbons using a Turkish natural zeolite as a template. The major carbon precursor used was furfuryl alcohol. Furfuryl alcohol was polymerized and carbonized between 700°C and 1000°C in the channels of the natural zeolite. The structure of the zeolite template and carbons were investigated by surface analysis techniques, scanning

Billur Sakintuna; Yuda Yürüm

2006-01-01

94

A yolk-shell structured Fe2O3@mesoporous SiO2 nanoreactor for enhanced activity as a Fenton catalyst in total oxidation of dyes.  

PubMed

Through a simple polymeric carbon assisted method, a yolk-shell structured Fe(2)O(3)@mesoporous SiO(2) nanoreactor was synthesized and showed excellent activity in Fenton-like reactions toward methylene blue total degradation. PMID:23403459

Cui, Zhi-Min; Chen, Zhe; Cao, Chang-Yan; Jiang, Lei; Song, Wei-Guo

2013-03-21

95

Hydrodesulphurization and hydrodenitrogenation of light gas oil using NiMo catalyst supported on functionalized mesoporous carbon  

Microsoft Academic Search

The effect of functionalization on the hydrotreating activity of NiMo catalysts supported on mesoporous carbon supports (mC) was studied. mC support was prepared by volume templating of alkali modified SBA-15 using sucrose as carbon source. The mC supports were functionalized using nitric acid of various concentrations (upto 8M HNO3). The supports and catalysts were characterized by N2 physisorption, SAXS, XRD,

N. Prabhu; A. K. Dalai; J. Adjaye

2011-01-01

96

Enhanced capacitive deionization of graphene/mesoporous carbon composites.  

PubMed

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?¹ 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?¹). The enhanced CDI performance of the composite electrodes can be attributed to the better conductive behaviour and higher specific surface area. PMID:22836788

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

2012-07-27

97

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

SciTech Connect

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.

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

2011-01-01

98

Cooperative acid-base effects with functionalized mesoporous silica nanoparticles: applications in carbon-carbon bond-formation reactions.  

PubMed

Acid-base bifunctional mesoporous silica nanoparticles (MSN) were prepared by a one-step synthesis by co-condensation of tetraethoxysilane (TEOS) and silanes possessing amino and/or sulfonic acid groups. Both the functionality and morphology of the particles can be controlled. The grafted functional groups were characterized by using solid-state (29)Si and (13)C cross-polarization/magic angle spinning (CP/MAS) NMR spectroscopy, thermal analysis, and elemental analysis, whereas the structural and the morphological features of the materials were evaluated by using XRD and N(2) adsorption-desorption analyses, and SEM imaging. The catalytic activities of the mono- and bifunctional mesoporous hybrid materials were evaluated in carbon-carbon coupling reactions like the nitroaldol reaction and the one-pot deacetalization-nitroaldol and deacetalization-aldol reactions. Among all the catalysts evaluated, the bifunctional sample containing amine and sulfonic acid groups (MSN-NNH(2)-SO(3)H) showed excellent catalytic activity, whereas the homogeneous catalysts were unable to initiate the reaction due to their mutual neutralization in solution. Therefore a cooperative acid-base activation is envisaged for the carbon-carbon coupling reactions. PMID:19569138

Shylesh, Sankaranarayanapillai; Wagner, Alex; Seifert, Andreas; Ernst, Stefan; Thiel, Werner R

2009-07-20

99

Synthesis of Mesoporous Carbon Materials via Enhanced Hydrogen-Bonding Interation  

Microsoft Academic Search

A general method based on two-phase polymerization has been described to synthesize mesoporous carbons via self-assembly. Mild reacting conditions and wide composition ranges are the obvious advantages of this method over the techniques previously reported.

Chengdu Liang; Sheng Dai

2006-01-01

100

Adsorption of malachite green from aqueous solutions onto ordered mesoporous carbons  

Microsoft Academic Search

The carbon materials with well-ordered mesoporous tubular structure were synthesized, which were confirmed by transmission electronmicroscopy (TEM), Raman spectrum, small angle X-ray diffraction (XRD), and N2 adsorption\\/desorption analysis. Moreover, by adjusting the ratio of furfuryl alcohol (FA) and trimethylbenzene (TMB), the structural parameters of the ordered mesoporous carbons (OMCs) could be facilely tuned. The materials synthesized were applied as a

Yong Tian; Ping Liu; Xiufang Wang; Hansen Lin

2011-01-01

101

A facile method for fabricating TiO2@mesoporous carbon and three-layered nanocomposites  

Microsoft Academic Search

Herein, we report a new and facile method for fabricating TiO2@mesoporous carbon hybrid materials. Uniform polydopamine (PDA) layers were coated onto the surface of titanate nanotubes (TNTs) and TiO2 nanorods (TNDs) through the spontaneous adhesion and self-polymerization of dopamine during the dipping process. Core–shell mesoporous carbon nanotubes with TiO2 nanorods or nanoparticles encapsulated inside (TiO2@MC) were then obtained by transforming

Yong Liu; Haibao Jin; Shenmin Zhu; Yunchun Liu; Mingce Long; Yongfeng Zhou; Deyue Yan

2012-01-01

102

Facile fabrication of copper-supported ordered mesoporous carbon for antibacterial behavior  

Microsoft Academic Search

Copper-supported ordered mesoporous carbon (Cu\\/CMK-3) was prepared by impregnating ordered mesoporous carbon (CMK-3) with CuCl2 aqueous solution. CMK-3 was served as a carrier for the continuous immobilization of Cu. The supported copper was observed to be the bivalence state, indicating that the Cu2+ ion was not reduced into cuprous species or metallic copper in the CMK-3. The BET surface area

Sanxiang Tan; Wujun Zou; Fengping Jiang; Shaozao Tan; Yingliang Liu; Dingsheng Yuan

2010-01-01

103

Synthesis of unique mesoporous ZrO 2-carbon fiber from collagen fiber  

Microsoft Academic Search

Hierarchical mesoporous ZrO2-carbon fiber was successfully synthesized by using collagen fiber as a structure-directing agent, and characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The ZrO2-carbon fiber obtained is approximately 1–4?m in outer diameter and 0.5–1mm in length, and the surface of the fiber exhibits ordered corn-cob-like mesoporous morphology.

Dehui Deng; Hao Wu; Xuepin Liao; Bi Shi

2008-01-01

104

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

SciTech Connect

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.

Babarao, Ravichandar [ORNL; Dai, Sheng [ORNL; Jiang, Deen [ORNL

2012-01-01

105

Pharmacological activity of ibuprofen released from mesoporous silica.  

PubMed

Novel drug delivery systems (DDS) to improve the pharmacokinetic profile of hydrophobic drugs following oral administration are an area of keen interest in drug research. An ideal DDS should not adversely affect drug activity, be capable of delivering a therapeutic dose of drug, and allow homogenous drug loading and drug release. Mesoporous silica has been proposed for this application, with ibuprofen employed as the model drug. It was hypothesised that mesoporous silica MCM-41 is capable of delivering a pharmacologically therapeutic dose of ibuprofen. Ibuprofen-loaded MCM-41 can be prepared reproducibly at a drug to carrier ratio of 30% (wt/wt). The release profile was seen to be 90% within 2 h. Initial assessment of COX-1 inhibitory activity suggests the absence of adverse effects attributable to drug-carrier interaction. The results of this study provide further evidence in support of the proposed use of mesoporous silica in drug delivery. PMID:22105222

Lang, Y; Finn, D P; Pandit, A; Walsh, P J

2011-11-22

106

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

PubMed Central

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 30 Å, and contained as much as 8.2 wt% 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 PdCl42- and H2VO41-. 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.

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

2012-01-01

107

Enhanced capacitive deionization of graphene/mesoporous carbon composites  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

108

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

109

The Influence of Microporosity on the Hydrogen Storage Capacity of Ordered Mesoporous Carbons  

Microsoft Academic Search

The adsorption of hydrogen on nanostructured carbons prepared by templating of mesoporous silicas has been studied at 77 K and between 0.1 and 1 MPa. The maximum capacity was obtained with a carbon synthetized by a sucrose liquid infiltration process in MCM-48 silica. It was observed that the hydrogen weight percentage which can be adsorbed on a carbon can be

Roger Gadiou; Nathalie Texier-Mandoki; Thierry Piquero; Seif-Eddine Saadallah; Julien Parmentier; Joël Patarin; Patrick David; Cathie Vix-Guterl

2005-01-01

110

Facile synthesis and application of a carbon foam with large mesopores.  

PubMed

By combining elements of hard- and soft-templating, a facile synthesis method for carbon foams with large mesopores has been demonstrated. A commercial Pluronic surfactant was used as the structure-directing agent as well as the carbon precursor. No micelle swelling agent or post treatment is necessary to enlarge mesopores. As such this method requires fewer synthesis steps and is highly scalable. The as-synthesized meso-carbons showed potential applications in the fields of carbon oxide capture and lithium-sulfur batteries. PMID:24121594

Fu, Liling; Qi, Genggeng; Sahore, Ritu; Sougrat, Rachid; Disalvo, Francis J; Giannelis, Emmanuel P

2013-10-23

111

Neutron imaging of ion transport in mesoporous carbon materials.  

PubMed

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

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

2013-06-11

112

Studies of Hydrogen Sorption on Mesoporous Carbon Composite Modified with Adsorbed Palladium  

Microsoft Academic Search

\\u000a Ordered mesoporous carbon composite based on the matrix synthesis protocol using mesoporous oxides as a template was prepared\\u000a and step-by-step structure formation was followed by X-ray diffraction, FTIR, N2 adsorption desorption and TPD mass-spectrometry. It was shown that property of composite is change considerably by Pd incorporation.\\u000a Transmission electron microscopy and Raman spectroscopy show that the framework of the highly

G. M. Telbiz; V. I. Gerda; N. G. Kobylinska; V. M. Zaitsev; J. Fraissard

113

Preparation, characterization, and catalytic activity of H 5 PMo 10 V 2 O 40 immobilized on nitrogen-containing mesoporous carbon (PMo 10 V 2 \\/N-MC) for selective conversion of methanol to dimethoxymethane  

Microsoft Academic Search

Nitrogen-containing mesoporous carbon (N-MC) was synthesized by a templating method using SBA-15 and polypyrrole as a templating\\u000a agent and a carbon precursor, respectively. The N-MC was then modified to have a positive charge, and thus, to provide a site\\u000a for the immobilization of [PMo10V2O40]5?. By taking advantage of the overall negative charge of [PMo10V2O40]5?, H5PMo10V2O40 (PMo10V2) catalyst was chemically immobilized

Heesoo Kim; Dong Ryul Park; Sunyoung Park; Ji Chul Jung; Sang-Bong Lee; In Kyu Song

2009-01-01

114

Hollow carbonated hydroxyapatite microspheres with mesoporous structure: hydrothermal fabrication and drug delivery property.  

PubMed

Hollow carbonated hydroxyapatite microspheres with mesoporous structure (HCHAs) have been fabricated by using calcium carbonated microspheres as sacrificial templates according to the following routes: (i) the in situ deposit of carbonated hydroxyapatite on the surfaces of CaCO3 microspheres by hydrothermal method and (ii) the removal of CaCO3 by chemical etching. The HCHAs consist of a hollow core and a mesoporous shell. Interestingly, the shell of the microspheres is constructed by carbonated hydroxyapatite nanoplates as building blocks. Moreover, these nanoplates are composed of many smaller nanoparticles with different crystal orientations, and the mesopores exist among these nanoparticles. The HCHAs exhibit the high drug-loading capacity and sustained drug release property, suggesting that the hierarchically porous microspheres have great potentials for bone-implantable drug-delivery applications. PMID:23706197

Guo, Ya-Jun; Wang, Ying-Ying; Chen, Ting; Wei, Yi-Ting; Chu, Lian-Feng; Guo, Ya-Ping

2013-04-01

115

Preparation, characterization, and photocatalytic activity of mesoporous TiO2 thin films.  

PubMed

Cubic-based ordered mesoporous TiO2 thin films were prepared by an evaporation-induced self-assembly method through a carefully controlling the hydrolysis/condensation conditions. The obtained sample exhibits mesoporous structure with a narrow pore size distribution. The TiO2 thin films have thick inorganic walls composed of nanocrystalline anatase. A reasonable explanation is also proposed to elucidate the formation of thick and stable mesoporous TiO2 films. The mesoporous TiO2 exhibits good photocatalytic activity. Nearly all the methyl orange has been degraded by the mesoporous TiO2 calcined at 500 degrees C. PMID:23646668

Wang, Jinshu; Li, Hui; Li, Hongyi; Wang, Hong; Cai, Qian

2013-02-01

116

Oxidative Dehydrogenation of Isobutane on Phosphorous-Modified Graphitic Mesoporous Carbon  

SciTech Connect

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.

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

2011-01-01

117

Comparative study on the magnetic properties of iron oxide nanoparticles loaded on mesoporous silica and carbon materials with different structure  

Microsoft Academic Search

Here we demonstrate the fabrication of magnetic iron oxide nanoparticles in SBA-15, KIT-6, hexagonally ordered mesoporous carbon (CMK-3), and carbon nanocage (CNC), and compare their unusual magnetic properties. We also demonstrate that pore diameter of the mesoporous silica supports dictates the particle diameter of the iron oxide nanoparticles confined in the porous matrix. The effect of the structure, composition, and

Sher Alam; Chokkalingam Anand; Radhakrishnan Logudurai; Veerappan V. Balasubramanian; Katsuhiko Ariga; Arumugam Chandra Bose; Toshiyuki Mori; Pavuluri Srinivasu; Ajayan Vinu

2009-01-01

118

Synthesis and characterization of spherical carbon and polymer capsules with hollow macroporous core and mesoporous shell structures  

Microsoft Academic Search

The synthesis and characterization of spherical carbon hollow capsules with mesoporous shell (HCMS) structures is reported. Silica spheres with sub-micrometer sized solid cores and mesoporous shell (SCMS) structures were used as templates in the synthesis. The resulting carbon capsules inversely replicated the morphology of the silica template and had uniform pores with a narrow pore size distribution centered at 3

Minsuk Kim; Suk Bon Yoon; Kwonnam Sohn; Jeong Yeon Kim; Chae-Ho Shin; Taeghwan Hyeon; Jong-Sung Yu

2003-01-01

119

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

PubMed

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

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

2012-09-19

120

Preparation and characterization of stable Ru nanoparticles embedded on the ordered mesoporous carbon material for applications in Fischer–Tropsch synthesis  

Microsoft Academic Search

A novel Ru–OMC catalyst was prepared by autoreduction reaction between a ruthenium precursor and a carbon source at 1123K. Ruthenium nanoparticles were embedded on the carbon walls of the ordered mesoporous carbon material. Characterization tools including power X-ray diffraction (XRD), nitrogen adsorption–desorption, and transmission electron microscopy (TEM) were used to scrutinize the catalysts. The catalyst activity for Fischer–Tropsch synthesis (FTS)

Kun Xiong; Jinlin Li; Kongyong Liew; Xiaodong Zhan

2010-01-01

121

Thermodynamic and neutron scattering study of hydrogen adsorption in two mesoporous ordered carbons.  

PubMed

Two mesoporous ordered carbon materials (MOCs) have been synthesized from silica templates by using sucrose as the carbon precursor. The textural characterization using Ar, N2, and CO2 adsorption combined with neutron diffraction showed that the two samples exhibit a significant microporous volume close to 0.5 cm3/g and an ordered network of mesopores. For both MCM48 and SBA15 templated carbons, adsorption first proceeds with the filling of micropores and then by the filling of mesopores with an adsorption energy close to the enthalpy of vaporization of bulk hydrogen. The hydrogen isosteric heat of adsorption in the micropores (6-8 kJ/mol) is significantly larger than that on the graphite surface (approximately 4 kJ/mol) but still too small for a reasonable use of these MOCs as hydrogen adsorbents for storage at room temperature. The neutron scattering study showed that the structure at 10 K of the adsorbed deuterium phase is poorly organized; it exhibits short and medium range orders of about 13 angstroms in micropores and about 20 angstroms in mesopores, respectively. The average distance between adsorbed molecules decreases with coverage by about 10%. In the mesopores, the diffracted line is consistent with a pseudohexagonal packing. PMID:16649772

Roussel, T; Pellenq, R J-M; Bienfait, M; Vix-Guterl, C; Gadiou, R; Béguin, F; Johnson, M

2006-05-01

122

Hierarchical carbon foams with independently tunable mesopore and macropore size distributions.  

PubMed

Hierarchical carbon foams with independently tunable mesopore and macropore size distributions were formed in a high internal phase emulsion (HIPE) template. The HIPE consists of an internal oil phase that controls the macropore dimensions and an aqueous resorcinol-formaldehyde precursor solution external phase that directs the mesopore size distribution. Once the emulsion is formed, the precursor solution is cured, fluid elements are extracted from the monolith via solvent exchange, and then the sample is pyrolyzed to create a hierarchical open-cell foam consisting of macropores with mesoporous carbon xerogel walls. Both mesopore and macropore size distributions may be independently tuned by changing the synthesis parameters. These samples have a peak in the mesopore size distribution that may be tuned to between 5 and 8 nm and macropore average diameters that may be tuned to between 0.7 and 2.1 microm. Furthermore, the 0.7 and 2.1 microm average diameter macropores have 0.18 and 0.53 microm diameter macropore windows between adjacent pores, respectively. Pore volumes up to 5.26 cm(3)/g and electrical conductivities as high as 0.34 S/cm are observed after 1200 degrees C carbonization of the framework. These foams may have potential applications as 3-D current collectors in batteries and as fuel cell catalyst supports. PMID:20491463

Gross, Adam F; Nowak, Andrew P

2010-07-01

123

New mesoporous silica\\/carbon composites by in situ transformation of silica template in carbon\\/silica nanocomposite  

Microsoft Academic Search

Hard template-based fabrication of mesoporous carbon unavoidably goes through the removal process of the template to generate template-free carbon replica, including troublesome disposal of template waste often accompanied by toxic etchant, which not only increases the fabrication cost of materials but also raises serious environmental concerns. As a novel strategy to overcome such problem, a direct in situ synthesis approach

Suk Bon Yoon; Byung-Seon Choi; Kuen-Woo Lee; Jei-Kwon Moon; Yong Suk Choi; Jong-Yun Kim; Hyunjin Cho; Jung Ho Kim; Min-Sik Kim; Jong-Sung Yu

2012-01-01

124

In situ synthesis of N and Cu functionalized mesoporous FDU-14 resins and carbons for electrochemical hydrogen storage  

Microsoft Academic Search

N and Cu cooperatively functionalized mesoporous resin and carbon materials with bicontinuous cubic structure (FDU-14) were obtained by a novel synthesis method. In this method, block copolymers were used as the templates as well as the precursors for the preparation of these modifying mesoporous materials. The CuC2O4 in the channels of mesoporous FDU-14 resins was gotten by in situ oxidation

AiGuo Kong; WenJuan Wang; Fan Yang; HanMing Ding; YongKui Shan

2010-01-01

125

Adsorptive separation studies of ethane-methane and methane-nitrogen systems using mesoporous carbon.  

PubMed

Adsorptive separations of C(2)H(6)/CH(4) and CH(4)/N(2) binary mixtures are of paramount importance from the energy and environmental points of view. A mesoporous carbon adsorbent was synthesized using a soft template method and characterized with TEM, TGA, and nitrogen adsorption/desorption. Adsorption equilibrium and kinetics of C(2)H(6), CH(4), and N(2) on the mesoporous carbon adsorbent were determined at 278, 298, and 318 K and pressures up to 100 kPa. The adsorption capacities of C(2)H(6) and CH(4) on the mesoporous carbon adsorbent at 298 K and 100 kPa are 2.20 mmol/g and 1.05 mmol/g, respectively. Both are significantly higher than those of many adsorbents including pillared clays and ETS-10 at a similar condition. The equilibrium selectivities of C(2)H(6)/CH(4) and CH(4)/N(2) at 298 K are 19.6 and 5.8, respectively. It was observed that the adsorption of C(2)H(6), CH(4), and N(2) gases on the carbon adsorbent was reversible with modest isosteric heats of adsorption, which implies that this carbon adsorbent can be easily regenerated in a cyclic adsorption process. These results suggest that the mesoporous carbon studied in this work is a promising alternative adsorbent for the separations of C(2)H(6)/CH(4) and CH(4)/N(2) gas mixtures. PMID:23312913

Yuan, Bin; Wu, Xiaofei; Chen, Yingxi; Huang, Jianhan; Luo, Hongmei; Deng, Shuguang

2012-12-19

126

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

PubMed

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

Vila, M; Cicuéndez, M; Sánchez-Marcos, J; Fal-Miyar, V; Manzano, M; Prieto, C; Vallet-Regi, M

2012-07-30

127

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

PubMed

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

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

2012-06-07

128

Effect of diffuse layer and pore shapes in mesoporous carbon supercapacitors  

SciTech Connect

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.

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

2010-01-01

129

Large-pore sized mesoporous carbon electrocatalyst for efficient dye-sensitized solar cells.  

PubMed

A counter-electrode comprised of large-pore sized mesoporous carbon exhibits low charge transfer resistance in iodide/triiodide redox electrolyte, thus liquid and quasi-solid dye sensitized solar cells show 8.18% and 3.61% solar to electric energy conversion efficiency, respectively. PMID:20221517

Ramasamy, Easwaramoorthi; Lee, Jinwoo

2010-02-15

130

Highly interconnected ordered mesoporous carbon-carbon nanotube nanocomposites: Pt-free, highly efficient, and durable counter electrodes for dye-sensitized solar cells.  

PubMed

We report the preparation of highly interconnected ordered mesoporous carbon-carbon nanotube nanocomposites which show Pt-like dye-sensitized solar cell (DSSC) efficiency and remarkable long-term durability as DSSC counter electrodes. PMID:22499057

Jo, Yimhyun; Cheon, Jae Yeong; Yu, Jeonghun; Jeong, Hu Young; Han, Chi-Hwan; Jun, Yongseok; Joo, Sang Hoon

2012-04-12

131

A novel organophosphorus hydrolase-based biosensor using mesoporous carbons and carbon black for the detection of organophosphate nerve agents  

Microsoft Academic Search

To detect organophosphate chemicals, which are used both as pesticides and as nerve agents, a novel biosensor based on organophosphorus hydrolase was developed. By using mesoporous carbon (MC) and carbon black (CB) as an anodic layer, the sensitivity of the sensor to p-nitrophenol (PNP), which is the product of the organophosphorus hydrolase reaction, was greatly improved. The MC\\/CB\\/glass carbon (GC)

Joon Hwan Lee; Jae Yeon Park; Kyoungseon Min; Hyung Joon Cha; Suk Soon Choi; Young Je Yoo

2010-01-01

132

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

PubMed

Ordered mesoporous carbide-derived carbon (OM-CDC) materials produced by nanocasting of ordered mesoporous silica templates are characterized by a bimodal pore size distribution with a high ratio of micropores. The micropores result in outstanding adsorption capacities and the well-defined mesopores facilitate enhanced kinetics in adsorption processes. Here, for the first time, a systematic study is presented, in which the effects of synthesis temperature on the electrochemical performance of these materials in supercapacitors based on a 1 M aqueous solution of sulfuric acid and 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid are reported. Cyclic voltammetry shows the specific capacitance of the OM-CDC materials exceeds 200 F g(-1) in the aqueous electrolyte and 185 F g(-1) in the ionic liquid, when measured in a symmetric configuration in voltage ranges of up to 0.6 and 2 V, respectively. The ordered mesoporous channels in the produced OM-CDC materials serve as ion-highways and allow for very fast ionic transport into the bulk of the OM-CDC particles. At room temperature the enhanced ion transport leads to 75% and 90% of the capacitance retention at current densities in excess of ?10 A g(-1) in ionic liquid and aqueous electrolytes, respectively. The supercapacitors based on 250-300 ?m OM-CDC electrodes demonstrate an operating frequency of up to 7 Hz in aqueous electrolyte. The combination of high specific capacitance and outstanding rate capabilities of the OM-CDC materials is unmatched by state-of-the art activated carbons and strictly microporous CDC materials. PMID:21449047

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

2011-03-30

133

Mesoporous silica coating on carbon nanotubes: layer-by-layer method.  

PubMed

It is of great interest to develop a simple, general, and easy-handling procedure for mesoporous silica coating. A facile, single-step method to coat iron oxide nanoparticles has been reported by Hyeon's group. However, up to present, this method only successfully applied to those zero-dimensional nanostructures heavily capped by cetyltrimethyl ammonium bromide (CTAB); no others are reported. It is unknown how this simple method is feasible in coating those nanostructures not capped by CTAB. Herein, using carbon nanotubes (CNTs) as the model, through an analogous layer-by-layer assembly method, many more CTAB molecules were found to anchor to CNTs, on which uniform mesoporous silica shells can successfully be formed by Hyeon's coating method. We believe that this contribution will pave the way for advancing the single-step method to become a general protocol in the mesoporous silica coating field. PMID:23672683

Deng, Xiaoyong; Qin, Ping; Luo, Man; Shao, Erlei; Zhao, Hui; Yang, Xing; Wang, Yanwen; Shen, Haifa; Jiao, Zheng; Wu, Minghong

2013-05-28

134

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

PubMed

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

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

2013-05-30

135

Synthesis of ternary metal nitride nanoparticles using mesoporous carbon nitride as reactive template.  

PubMed

Mesoporous graphitic carbon nitride was used as both a nanoreactor and a reactant for the synthesis of ternary metal nitride nanoparticles. By infiltration of a mixture of two metal precursors into mesoporous carbon nitride, the pores act first as a nanoconfinement, generating amorphous mixed oxide nanoparticles. During heating and decomposition, the carbon nitride second acts as reactant or, more precisely, as a nitrogen source, which converts the preformed mixed oxide nanoparticles into the corresponding nitride (reactive templating). Using this approach, ternary metal nitride particles with diameters smaller 10 nm composed of aluminum gallium nitride (Al-Ga-N) and titanium vanadium nitride (Ti-V-N) were synthesized. Due to the confinement effect of the carbon nitride matrix, the composition of the resulting metal nitride can be easily adjusted by changing the concentration of the preceding precursor solution. Thus, ternary metal nitride nanoparticles with continuously adjustable metal composition can be produced. PMID:19206283

Fischer, Anna; Müller, Jens Oliver; Antonietti, Markus; Thomas, Arne

2008-12-23

136

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

SciTech Connect

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.

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

2012-01-01

137

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

PubMed

Core-shell-structured mesoporous silica spheres were prepared by using n-octadecyltrimethoxysilane (C18TMS) as the surfactant. Hollow mesoporous carbon spheres with controllable diameters were fabricated from core-shell-structured mesoporous silica sphere templates by chemical vapor deposition (CVD). By controlling the thickness of the silica shell, hollow carbon spheres (HCSs) with different diameters can be obtained. The use of ethylene as the carbon precursor in the CVD process produces the materials in a single step without the need to remove the surfactant. The mechanism of formation and the role played by the surfactant, C18TMS, are investigated. The materials have large potential in double-layer supercapacitors, and their electrochemical properties were determined. HCSs with thicker mesoporous shells possess a larger surface area, which in turn increases their electrochemical capacitance. The samples prepared at a lower temperature also exhibit increased capacitance as a result of the Brunauer-Emmett-Teller (BET) area and larger pore size. PMID:23929713

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

2013-08-08

138

Kinetics and equilibrium of adsorption of organic solutes on mesoporous carbons  

NASA Astrophysics Data System (ADS)

Static and kinetic studies on adsorption of nitrobenzene, 4-nitrophenol and 4-chlorophenol on two mesoporous carbons are performed. The carbon properties are analyzed by means of nitrogen adsorption. The adsorption experiments are performed in acidic buffer solutions in a wide range of concentrations. The static experiments are analyzed by means of Langmuir Freundlich and Freundlich isotherms. The Lagergren, pseudo-second-order, intraparticle-diffusion and multi-exponent equations are used in the analysis of kinetic equilibria.

Marczewski, Adam W.

2007-04-01

139

Synthesis and characterization of ruthenium-containing ordered mesoporous carbon with high specific surface area  

Microsoft Academic Search

A Ru-containing ordered mesoporous carbon with a high specific surface area of 2186m2\\/g was synthesized through evaporation-induced multi-constituent co-assembly method, wherein soluble resol polymer is used as the carbon precursor, silicate oligomers as the inorganic precursor, triblock copolymer as the template, and RuCl3·3H2O as the Ru precursor. The resultant sample was characterized by X-ray diffraction, nitrogen sorption, transmission electron microscopy

Zhihong Ji; Shuguang Liang; Yanbin Jiang; Hao Li; Zhimin Liu; Tong Zhao

2009-01-01

140

Synthesis and characterization of mesoporous ZSM-12 by using carbon particles  

Microsoft Academic Search

The generation of mesoporosity in 1-dimensional zeolite ZSM-12 was explored by using carbon black as template for the expected mesoporosity during synthesis. After the carbon particles were burned off, intracrystalline mesopore networks were formed. For relatively high C\\/Si and H2O\\/Si ratios, there is higher opportunity to generate mesoporosity. All the samples were characterized by X-ray diffraction, nitrogen physisorption, SEM, ICP

Xiaotong Wei; Panagiotis G. Smirniotis

2006-01-01

141

Mesoporous carbon as a novel drug carrier of fenofibrate for enhancement of the dissolution and oral bioavailability.  

PubMed

The purpose of this study was to develop mesoporous carbon loaded with a poorly watersoluble drug to enhance the drug dissolution and improve the oral bioavailability. Mesoporous carbon was synthesized using Pluronic 127 triblock polymer (F127), TEOS and phenolic resins. Fenofibrate (FFB) was chosen as a model drug and loaded onto mesoporous carbon using three different loading methods involving incipient wetness impregnation, and the solvent and melting methods. The effect of the physical state and the specific surface area were investigated using nitrogen adsorption, transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was found that the physicochemical properties of the drug as well as the drug loading methods had critical effects on the drug release rate. In vitro drug release studies showed that incorporation of FFB in mesoporous carbon greatly enhanced the dissolution rate in comparison with that of the pure crystalline drug. Moreover, the oral bioavailability of the drug from mesoporous carbon was higher than that of FFB commercial capsules. Furthermore, mesoporous carbon produced no irritation of the mucosa of the gastrointestinal tract as shown by gastric mucosa irritation test. PMID:23688621

Niu, Xia; Wan, Long; Hou, Zhong; Wang, Tianyi; Sun, Changshan; Sun, Jin; Zhao, Peng; Jiang, Tongying; Wang, Siling

2013-05-17

142

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

NASA Astrophysics Data System (ADS)

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-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.

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

2007-02-01

143

Preparation, phase transformation and photocatalytic activities of cerium-doped mesoporous titania nanoparticles  

NASA Astrophysics Data System (ADS)

Cerium-doped mesoporous TiO2 nanoparticles with high surface area and thermal stable anatase wall were synthesized via hydrothermal process in a cetyltrimethylammonium bromide (CTAB)/Ti(SO4)2/Ce(NO3)4/H2O system. The obtained materials were characterized by XRD, FESEM, HRTEM, FTIR spectroscopy, nitrogen adsorption and DRS spectra. Experimental results indicated that the doping of cerium not only increased the surface area of mesoporous TiO2 nanoparticles, but also inhibited the mesopores collapse and the anatase-to-rutile phase transformation. Moreover, the undoped, doped anatase mesoporous nanoparticles exhibit higher photocatalytic activity than commercial photocatalyst (Degussa, P25), but the maximum photodegradation rate corresponds to the undoped mesoporous TiO2 nanoparticles. The lower photocatalytic activities of cerium-doped samples compared with undoped one may be ascribed to that the doped cerium partially blocks titania's surface sites available for the photodegradation and absorption of Rhodamine B (RB).

Xiao, Jiangrong; Peng, Tianyou; Li, Ran; Peng, Zhenghe; Yan, Chunhua

2006-04-01

144

Mesoporous Carbons from Poly(acrylonitrile)-b-poly(E-caprolactone) Block Copolymers  

SciTech Connect

A series of degradable block copolymers, poly(acrylonitrile)-b-poly({epsilon}-caprolactone) (PAN-PCL), have been synthesized by sequential living polymerization in this study. Well-defined, microphase-separated PAN-PCL microdomains can be efficiently achieved in the bulk by using appropriate solvents. The microphase-separated lamellar samples were then used as templates to produce mesoporous carbons at which large amounts of porous texture in carbonized PAN matrix were formed after degradation of PCL due to randomly oriented lamellar texture (namely, interconnection of PCL microdomains). The thermal profiles for efficient stabilization were examined by differential scanning calorimetry and thermogravimetric analyses as well as Fourier transform infrared spectroscopy. Consequently, mesoporous carbon materials might be prepared as evidenced by transmission electron microscopy, field emission scanning electron microscopy, and small-angle X-ray scattering. The formation of carbonized materials was identified in accordance with the presence of carbon diffractions by wide-angle X-ray diffraction. In contrast to the thermal stability of the carbonization of PAN homopolymers, it is noted that the carbonization procedure can be achieved in the PAN-PCL system regardless of the stretching process (that is an essential process to improve the thermal stability of PAN carbonization). We speculate that this unique feature for the carbonization of PAN copolymers might be attributed to the stretched chains of PAN under nanoscale confined environment.

Ho,R.; Wang, T.; Lin, C.; Yu, T.

2007-01-01

145

Photoreactive mesoporous carbon/Bi2WO6 composites: Synthesis and reactivity  

NASA Astrophysics Data System (ADS)

In order to develop highly efficient visible-light induced photocatalysts, Bi2WO6 powders and mesoporous carbon (MC)-modified Bi2WO6 (MC/Bi2WO6) photocatalysts were synthesized via a simple hydrothermal process in this paper. The samples of Bi2WO6 and MC/Bi2WO6 were characterized by X-ray diffraction (XRD), UV–visible spectroscopy, scanning electron microscopy (SEM) and BET surface area analysis, and their photocatalytic activity were evaluated by photocatalytic decoloration of rhodamine B (RhB) aqueous solution under visible light. It was found that the presence of MC could significantly improve the crystallization of Bi2WO6 species and photoabsorption property of Bi2WO6 in the visible region. The results also showed that the BET surface areas of MC/Bi2WO6 composites were larger than that of the pure Bi2WO6 and the photocatalytic activity of the MC/Bi2WO6 is much higher than that of Bi2WO6 with the optimum effect occurring at RMC = 0.10 (the weight ratio of MC to Bi2WO6). Close investigation revealed that the surface area, grain size and charge transfer of the as-prepared MC/Bi2WO6 composites could improve the photocatalytic activities.

Chen, Su-Hua; Yin, Zhen; Luo, Sheng-Lian; Li, Xue-Jun; Yang, Li-Xia; Deng, Fang

2012-10-01

146

Mesoporous carbon@silicon-silica nanotheranostics for synchronous delivery of insoluble drugs and luminescence imaging.  

PubMed

A hierarchical theranostic nanostructure with carbon and Si nanocrystals respectively encapsulated in the mesopores and within the framework of mesoporous silica nanoparticles (CS-MSNs) was constructed by a bottom-up self-assembly strategy combining an in situ one-step carbonization/crystallization approach. CS-MSNs exhibited narrow size distribution, high payload of insoluble drugs and unique NIR-to-Vis luminescence imaging feature. The bio-conjugated CS-MSNs with a PEGylated phospholipid compound and hyaluronic acid showed excellent dispersivity and could specifically target cancer cells overexpressing CD44, deliver insoluble drugs into these cells and consequently kill them effectively, and also fluorescently image them simultaneously in a unique and attractive NIR-to-Vis luminescence imaging fashion, providing a promising opportunity for cancer theranostics. PMID:22425026

He, Qianjun; Ma, Ming; Wei, Chenyang; Shi, Jianlin

2012-03-16

147

Nanocomposite of LiFePO4 and mesoporous carbon for high power cathode of lithium rechargeable batteries.  

PubMed

A composite of LiFePO4 and MgO-templated disordered mesoporous carbon was prepared through infiltrating a LiFePO4 precursor solution into the mesoporous carbon and growing LiFePO4 nanocrystals in the pore of the carbon. Transmission electron microscope (TEM) and scanning electron microscope (SEM) analysis showed that LiFePO4 nanoparticles are embedded homogeneously in the mesoporous carbon without formation of big LiFePO4 particles out of the pores. The pores of the carbon are believed to suppress crystal growth of LiFePO4. The 3-dimensional conducting carbon network between the LiFePO4 nanoparticles led to excellent cycling stability and rate capability. The composite showed no fade of discharge capacity up to 100 cycles and 85% of the reversible capacity at 0.1 C was retained at 30 C. PMID:23421233

Kim, Jun-Il; Roh, Kwang Chul; Lee, Jae-Won

2012-11-01

148

High sulfur loading cathodes fabricated using peapodlike, large pore volume mesoporous carbon for lithium-sulfur battery.  

PubMed

Porous carbon materials with large pore volume are crucial in loading insulated sulfur with the purpose of achieving high performance for lithium-sulfur batteries. In our study, peapodlike mesoporous carbon with interconnected pore channels and large pore volume (4.69 cm(3) g(-1)) was synthesized and used as the matrix to fabricate carbon/sulfur (C/S) composite which served as attractive cathodes for lithium-sulfur batteries. Systematic investigation of the C/S composite reveals that the carbon matrix can hold a high but suitable sulfur loading of 84 wt %, which is beneficial for improving the bulk density in practical application. Such controllable sulfur-filling also effectively allows the volume expansion of active sulfur during Li(+) insertion. Moreover, the thin carbon walls (3-4 nm) of carbon matrix not only are able to shorten the pathway of Li(+) transfer and conduct electron to overcome the poor kinetics of sulfur cathode, but also are flexible to warrant structure stability. Importantly, the peapodlike carbon shell is beneficial to increase the electrical contact for improving electronic conductivity of active sulfur. Meanwhile, polymer modification with polypyrrole coating layer further restrains polysulfides dissolution and improves the cycle stability of carbon/sulfur composites. PMID:23452385

Li, Duo; Han, Fei; Wang, Shuai; Cheng, Fei; Sun, Qiang; Li, Wen-Cui

2013-03-15

149

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

PubMed

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

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

2013-05-22

150

Patterned mesoporous media via 3-D replication in supercritical Carbon dioxide.  

NASA Astrophysics Data System (ADS)

Mesoporous metal oxide films having cylindrical channels oriented normal to the surface have generated intense interest due to their potential use as sensors, catalysts and detection devices. Further, the ability to pattern these mesostructured films makes it versatile to generate mesoporous materials with precisely controlled geometries and morphologies. Here we describe a novel route to mesoporous silica films with perpendicular nanochannels prepared by the 3-D replication of block copolymer templates in supercritical carbon dioxide. Templates comprised of poly(alpha-methyl styrene) cylinders oriented normal in the matrix of poly (hydroxy styrene) having trace amounts of acid catalyst was infused with solutions of silica precursor in sc CO2 to selectively deposit silica within the matrix. Calcination yielded the porous silica arrays. The phase selective deposition was enabled by segregation of acid catalyst into hydrophilic matrix. Substitution of acid catalyst with photo sensitive acid generators facilitates to pattern the mesoporous films, which could potentially have applications in microfluidic devices and low-dielectric constant layers for microelectronic devices.

Nagarajan, Sivakumar; Russell, Thomas; Watkins, James; Bosworth, Joan; Busch, Peter; Smilgies, Detlef; Ober, Christopher

2006-03-01

151

An amperometric sensor for uric acid based on ordered mesoporous carbon-modified pyrolytic graphite electrode  

Microsoft Academic Search

A novel amperometric sensor for uric acid based on ordered mesoporous carbon modified pyrolytic graphite electrode was developed.\\u000a Uric acid oxidation was easily catalyzed by this electrode in a phosphate buffer solution at pH 7.0, with an anodic potential\\u000a decrease about 140 mV compared to bare pyrolytic graphite electrode. The uric acid level was determined by the amperometric\\u000a method, at

Yonggen Ma; Guangzhi Hu; Shijun Shao; Yong Guo

2009-01-01

152

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

PubMed

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

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

2013-01-16

153

The local and surface structure of ordered mesoporous carbons from nitrogen sorption, NEXAFS and synchrotron radiation studies  

Microsoft Academic Search

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

Michael A. Smith; Raul F. Lobo

2006-01-01

154

Preparation of activated carbon microspheres from phenolic-resin by supercritical water activation  

Microsoft Academic Search

Supercritical water (SCW) has been employed as an efficient activating agent for the preparation of activated carbon microspheres (P-ACS) with developed mesopores from phenolic-resin. Several processing factors that influenced the activation reaction, including activation temperature, activation duration, supercritical pressure and water flow rate were investigated. Increasing activation temperature and duration lead to larger porosity and higher specific surface area as

Qiong Cai; Zheng-Hong Huang; Feiyu Kang; Jun-Bing Yang

2004-01-01

155

General Synthesis of Discrete Mesoporous Carbon Microspheres through a Confined Self-Assembly Process in Inverse Opals.  

PubMed

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

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

2013-09-23

156

Nanoscale enzyme reactors in mesoporous carbon for improved performance and lifetime of biosensors and biofuel cells.  

PubMed

Nanoscale enzyme reactors (NERs) of glucose oxidase in conductive mesoporous carbons were prepared in a two-step process of enzyme adsorption and follow-up enzyme crosslinking. MSU-F-C, a mesoprous carbon, has a bottleneck pore structure with mesocellular pores of 26 nm connected with window mesopores of 17 nm. This structure enables the ship-in-a-bottle mechanism of NERs, which effectively prevents the crosslinked enzymes in mesocellular pores from leaching through the smaller window mesopores. This NER approach not only stabilized the enzyme but also expedited electron transfer between the enzyme and the conductive MSU-F-C by maintaining a short distance between them. In a comparative study with GOx that was simply adsorbed without crosslinking, the NER approach was proven to be effective in improving the sensitivity of glucose biosensors and the power density of biofuel cells. The power density of biofuel cells could be further improved by manipulating several factors, such as by adding a mediator, changing the order of adsorption and crosslinking, and inserting a gold mesh as an electron collector. PMID:20673623

Kwon, Ki Young; Youn, Jongkyu; Kim, Jae Hyun; Park, Yongjin; Jeon, Chulmin; Kim, Byoung Chan; Kwon, Yongchai; Zhao, Xueyan; Wang, Ping; Sang, Byoung In; Lee, Jinwoo; Park, Hyun Gyu; Chang, Ho Nam; Hyeon, Taeghwan; Ha, Su; Jung, Hee-Tae; Kim, Jungbae

2010-07-08

157

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

SciTech Connect

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

Feng, Jicheng; Zhao, Jiachang; Tang, Bohejin; Liu, Ping [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Xu, Jingli, E-mail: jinglixu@sues.edu.c [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China)

2010-12-15

158

Voltammetric detection of riboflavin based on ordered mesoporous carbon modified electrode  

Microsoft Academic Search

The potential application of ordered mesoporous carbon (OMC)-modified glassy carbon electrode (OMC\\/GCE) in electrochemistry\\u000a as a novel electrode material was investigated. X-ray diffraction, transmission electron micrographs, and cyclic voltammetry\\u000a were used to characterize the structure and electrochemical behaviors of this material. Compared to GC electrode, the peak\\u000a currents of potassium ferricyanide (K3[Fe(CN)6]) increase and the peak potential separation (?E\\u000a p)

Jing Bai; Jean Chrysostome Ndamanisha; Lin Liu; Li Yang; Liping Guo

2010-01-01

159

Heterogeneous catalytic activity of platinum nanoparticles hosted in mesoporous silica thin films modified with polyelectrolyte brushes.  

PubMed

Platinum nanoparticles of 3 nm diameter were included in mesoporous silica thin films by controlling the mesopore surface charge with a short polymer brush. This metal-polymer-mesopore nanocomposite presents high catalytic activity toward ammonia oxidation at low temperatures with 4.5% weight platinum loading. An anomalous partial selectivity toward nitrous oxide is observed for the first time, which can be traced back to the synergy of the particles and modified surface. This effect opens a path toward the design of nanocomposite catalysts with highly controlled environments, in which the size- and function-controlled cavities can be tuned in order to lower the reaction barriers. PMID:24020748

Rafti, Matías; Brunsen, Annette; Fuertes, M Cecilia; Azzaroni, Omar; Soler-Illia, Galo J A A

2013-09-12

160

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

PubMed

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

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

2013-03-27

161

Double-layer capacitance of waste coffee ground activated carbons in an organic electrolyte  

Microsoft Academic Search

Using ZnCl2 activation we prepared a series of carbon electrodes from waste coffee grounds to study the effect of mesopores on double-layer capacitance in a tetraethyl ammonium tetrafluoroborate\\/acetonitrile electrolyte. The activated carbon with the largest mesopore volume achieved an energy density of 34Whkg?1 at low current loads, and significantly retained an energy density of 16.5Whkg?1 and specific capacitance of more

Thomas E. Rufford; Denisa Hulicova-Jurcakova; Erika Fiset; Zhonghua Zhu; Gao Qing Lu

2009-01-01

162

Analysis of the microporous texture of a glassy carbon by adsorption measurements and Monte Carlo simulation. Evolution with chemical and physical activation  

Microsoft Academic Search

A mesoporous glassy carbon has been chemically (KOH) and physically (CO2) activated in order to improve its micropore volume while preserving the well-defined mesopore network. The microporosity of the glassy carbon and the evolution of the micropore texture with activation have been studied by means of Monte Carlo simulation and gas adsorption. Micropore size distributions obtained from simulated adsorption isotherms

M. Pérez-Mendoza; C. Schumacher; F. Suárez-García; M. C. Almazán-Almazán; M. Domingo-García; F. J. López-Garzón; N. A. Seaton

2006-01-01

163

Dynamic pesticide removal with activated carbon fibers.  

PubMed

Rapid small-scale minicolumn tests were carried out to simulate the atrazine adsorption in water phase with three pelletized pitch-based activated carbon fibers (ACF) and one commercial granular activated carbon (GAC). Initial atrazine solutions were prepared with pretreated ground water. Minicolumn tests showed that the performance of highly activated carbon fibers (surface area of 1700 m2/g) is around 7 times better than the commercial GAC (with surface area at around 1100 m2/g), whereas carbon fibers with medium activation degree (surface area of 1500 m2/g) had a removal efficiency worse than the commercial carbon. The high removal efficiency of the highly activated ACF is due to the wide-opened microstructure of the material, with an appreciable contribution of the low size mesopores, maintaining at these conditions a fast kinetic adsorption rate rather than a selective adsorbent for micropollutants vs. natural organic matter. PMID:11229006

Martín-Gullón, I; Font, R

2001-02-01

164

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

PubMed

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

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

165

Photocatalytic activity of titania modified mesoporous silica for pollution control  

Microsoft Academic Search

A series of titania modified mesoporous silicates with variable Si\\/Ti ratios were prepared using titanium tetrabutoxide by impregnation method. The samples were characterized by different analytical techniques such as XRD, TEM, FT-IR, low temperature N2 sorption, and UV–Vis diffused reflectance spectroscopy. The TiO2 supported on mesoporous silica was found to be in the anatase form. Crystallite size calculated using Scherrer’s

A. A. Belhekar; S. V. Awate; R. Anand

2002-01-01

166

Esterification of 4-methoxyphenylacetic acid with dimethyl carbonate over mesoporous sulfated zirconia  

Microsoft Academic Search

Mesoporous zirconia was synthesized using cetyltrimethylammonium bromide as template under hydrothermal conditions. The surfactant was removed by ethanol extraction. The resultant mesoporous material was further treated with sulfuric acid and calcined in air at 450°C for 5h to obtain mesoporous sulfated zirconia (MSZ). The mesoporous sulfated zirconia was characterized by XRD and N2 adsorption and desorption measurements. Esterification of 4-methoxyphenylacetic

Venu Gopal Devulapelli; Hung-Shan Weng

2009-01-01

167

Construction of label-free electrochemical immunosensor on mesoporous carbon nanospheres for breast cancer susceptibility gene.  

PubMed

In this contribution, mesoporous carbon nanospheres (MCN) were used to fabricate a label-free electrochemical immunosensor for breast cancer susceptibility gene (BRCAl). The detection platform was constructed by conjugation of anti-BRCA1 on glassy carbon electrodes which were modified by mesoporous carbon nanospheres-toluidine blue nanocomposite (MCN-TB)/room temperature ionic-liquid (RTIL) composited film. TB was adsorbed onto MCN and acted as a redox probe. The electroactivity of TB was greatly enhanced in the presence of MCN. The good conductivity of MCN and BMIM·BF4 could promote the electron transfer and thus enhance the detection sensitivity. Moreover, the large surface area of MCN and the protein-binding properties of BMIM·BF4 could greatly increase the antibody loading. The specific antibody-antigen immunoreaction on the electrode surface resulted in a decrease of amperometric signal of the electrode. Under optimized conditions, the amperometric signal decreased linearly with BRCAl concentration in the range of 0.01-15 ng mL(-1) with a low detection limit of 3.97 pg mL(-1). The immunosensor exhibits high sensitivity, good selectivity and stability. PMID:23498687

Fan, Haixia; Zhang, Yong; Wu, Dan; Ma, Hongmin; Li, Xiaojing; Li, Yan; Wang, Huan; Li, He; Du, Bin; Wei, Qin

2013-02-12

168

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

PubMed

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

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

2013-08-01

169

Microporous and mesoporous carbon nanostructures with the inverse opal lattice  

NASA Astrophysics Data System (ADS)

The conditions for porous structure formation in carbon nanostructures with the inverse opal lattice have been studied. The characteristics of the porous structure have been determined by means of the gas adsorption-desorption. The morphology and structure of samples have been examined using high-resolution transmission electron microscopy.

Emel'chenko, G. A.; Masalov, V. M.; Zhokhov, A. A.; Khodos, I. I.

2013-05-01

170

Triconstituent co-assembly to ordered mesostructured polymer-silica and carbon-silica nanocomposites and large-pore mesoporous carbons with high surface areas.  

PubMed

Highly ordered mesoporous polymer-silica and carbon-silica nanocomposites with interpenetrating networks have been successfully synthesized by the evaporation-induced triconstituent co-assembly method, wherein soluble resol polymer is used as an organic precursor, prehydrolyzed TEOS is used as an inorganic precursor, and triblock copolymer F127 is used as a template. It is proposed for the first time that ordered mesoporous nanocomposites have "reinforced concrete"-structured frameworks. By adjusting the initial mass ratios of TEOS to resol, we determined the obtained nanocomposites possess continuous composition with the ratios ranging from zero to infinity for the two constituents that are "homogeneously" dispersed inside the pore walls. The presence of silicates in nanocomposites dramatically inhibits framework shrinkage during the calcination, resulting in highly ordered large-pore mesoporous carbon-silica nanocomposites. Combustion in air or etching in HF solution can remove carbon or silica from the carbon-silica nanocomposites and yield ordered mesoporous pure silica or carbon frameworks. The process generates plenty of small pores in carbon or/and silica pore walls. Ordered mesoporous carbons can then be obtained with large pore sizes of approximately 6.7 nm, pore volumes of approximately 2.0 cm(3)/g, and high surface areas of approximately 2470 m(2)/g. The pore structures and textures can be controlled by varying the sizes and polymerization degrees of two constituent precursors. Accordingly, by simply tuning the aging time of TEOS, ordered mesoporous carbons with evident bimodal pores at 2.6 and 5.8 nm can be synthesized. PMID:16939291

Liu, Ruili; Shi, Yifeng; Wan, Ying; Meng, Yan; Zhang, Fuqiang; Gu, Dong; Chen, Zhenxia; Tu, Bo; Zhao, Dongyuan

2006-09-01

171

Effect of the preparation of a mesoporous sulfated zirconia catalyst in n-butane isomerization activity  

Microsoft Academic Search

The n-butane isomerization activity of a mesoporous sulfated zirconia is shown to be a strong function of the extent of hydration on the catalyst surface. Regeneration of the catalyst at 500°C in oxygen must be followed by a water exposure step to rehydrate the catalyst and recapture its original activity. Pretreatment drying procedures are critical in determining optimal activity on

Michael Risch; E. E. Wolf

2001-01-01

172

Enhanced enzymatic thermal stability and activity in functionalized mesoporous silica monitored by (31) p NMR.  

PubMed

Organophosphorus hydrolase (OPH) is immobilized on ammonium-modified mesoporous silica particles. Thermal stability and activity are measured with a (31) P NMR assay of the conversion of paraoxon (toxic) to its non-toxic hydrolysis product. After immobilization, OPH is significantly more active at room temperature and retained activity even after being heated to 45 °C for 1 month. PMID:23184722

El-Boubbou, Kheireddine; Schofield, David A; Landry, Christopher C

2012-02-29

173

Switchable fluorescent imaging of intracellular telomerase activity using telomerase-responsive mesoporous silica nanoparticle.  

PubMed

This work designs a telomerase-responsive mesoporous silica nanoparticle (MSN) to realize in situ "off-on" imaging of intracellular telomerase activity. In the wrapping DNA (O1) sealed MSN probe, a black hole fluorescence quencher is covalently immobilized on the inner walls of the mesopores, while fluorescein is loaded in the mesopores. In the presence of telomerase and dNTPs, the designed O1 can be extended and then moves away from the MSN surface via forming a rigid hairpin-like DNA structure. Thus the O1 can act as a "biogate" to block and release fluorescein for "off-on" switchable fluorescent imaging. The MSN probe exhibits good performance for sensitive in situ tracking of telomerase activity in living cells. The practicality of this protocol has been verified by monitoring the change of cellular telomerase activity in response to telomerase-related drugs. PMID:23978191

Qian, Ruocan; Ding, Lin; Ju, Huangxian

2013-08-29

174

Ordered mesoporous carbons synthesized by a modified sol–gel process for electrosorptive removal of sodium chloride  

Microsoft Academic Search

Capacitive deionization (CDI) represents an alternative process to remove the ions from the brackish water. In this study two series of ordered mesoporous carbons (OMCs) that demonstrated the potential use for capacitive desalination have been synthesized by a modified sol–gel process involving nickel salts. It was shown that the preferred formation of crown-ether type complexes between nickel ions and triblock

Lixia Li; Linda Zou; Huaihe Song; Gayle Morris

2009-01-01

175

Preparation, phase transformation and photocatalytic activities of cerium-doped mesoporous titania nanoparticles  

SciTech Connect

Cerium-doped mesoporous TiO{sub 2} nanoparticles with high surface area and thermal stable anatase wall were synthesized via hydrothermal process in a cetyltrimethylammonium bromide (CTAB)/Ti(SO{sub 4}){sub 2}/Ce(NO{sub 3}){sub 4}/H{sub 2}O system. The obtained materials were characterized by XRD, FESEM, HRTEM, FTIR spectroscopy, nitrogen adsorption and DRS spectra. Experimental results indicated that the doping of cerium not only increased the surface area of mesoporous TiO{sub 2} nanoparticles, but also inhibited the mesopores collapse and the anatase-to-rutile phase transformation. Moreover, the undoped, doped anatase mesoporous nanoparticles exhibit higher photocatalytic activity than commercial photocatalyst (Degussa, P25), but the maximum photodegradation rate corresponds to the undoped mesoporous TiO{sub 2} nanoparticles. The lower photocatalytic activities of cerium-doped samples compared with undoped one may be ascribed to that the doped cerium partially blocks titania's surface sites available for the photodegradation and absorption of Rhodamine B (RB)

Xiao Jiangrong [Department of Chemistry, Centre of Nanoscience and Nanotechnology Research, Wuhan University, Wuhan 430072 (China); Peng Tianyou [Department of Chemistry, Centre of Nanoscience and Nanotechnology Research, Wuhan University, Wuhan 430072 (China)]. E-mail: typeng@whu.edu.cn; Li Ran [Department of Chemistry, Centre of Nanoscience and Nanotechnology Research, Wuhan University, Wuhan 430072 (China); Peng Zhenghe [Department of Chemistry, Centre of Nanoscience and Nanotechnology Research, Wuhan University, Wuhan 430072 (China); Yan Chunhua [State Key Laboratory of Rare Earth Materials Chemistry and Applications, Peking University, Beijing 100871 (China)

2006-04-15

176

Effect of pore structure and surface chemistry of virgin activated carbons on removal of hydrogen sulfide  

Microsoft Academic Search

Three activated carbons of various origins were tested as H2S adsorbents, chosen to differ significantly in surface area, pore structure and surface chemistry. The carbons were characterized by sorption of nitrogen and water vapor, potentiometric titration, Boehm titration, and thermal analysis. The results showed that a heterogeneous carbon (having micro- and mesopores) with chemical surface functionality performs better than apparently

Teresa J Bandosz

1999-01-01

177

Impact of film thickness on the morphology of mesoporous carbon films using organic-organic self-assembly.  

PubMed

Mesoporous polymer and carbon thin films are prepared by the organic-organic self-assembly of an oligomeric phenolic resin with an amphiphilic triblock copolymer template, Pluronic F127. The ratio of resin to template is selected such that a body-centered cubic (Im3m) mesostructure is formed in the bulk. However, well-ordered mesoporous films are not always obtained for thin films (<100 nm), and this behavior is found to be directly correlated with the initial phenolic resin to template ratio. Furthermore, the symmetry of ordered phases is highly dependent on the number of layers of spheres in the film: Monolayers and bilayers are characterized by hexagonal close-packed (HCP) symmetry, while films with approximately 5 layers of spheres exhibit a mixture of HCP and face-centered orthorhombic (FCO) structures. Ultrathick films having more than 30 layers of spheres are similar to the bulk body-centered cubic symmetry with a preferential orientation of the closest-packed (110) plane parallel to the substrate. Film thickness and initial composition of the carbonizable precursors in the template are critical factors in determining the morphology of mesoporous carbon films. These results provide insight into why difficulties have been reported in producing ultrathin ordered mesoporous carbon films using cooperative organic-organic self-assembly. PMID:21466222

Vogt, Bryan D; Chavez, Vicki L; Dai, Mingzhi; Arreola, M Regina Croda; Song, Lingyan; Feng, Dan; Zhao, Dongyuan; Perera, Ginusha M; Stein, Gila E

2011-04-05

178

Highly sensitive determination of capsaicin using a carbon paste electrode modified with amino-functionalized mesoporous silica.  

PubMed

Mesoporous silica (MS) and amino-functionalized mesoporous silica (NH(2)-FMS) were prepared and characterized using the techniques of transmission electron microscopy (TEM) and nitrogen adsorption-desorption. Voltammetry was used to investigate the electrochemical behavior of capsaicin at the amino-functionalized mesoporous silica, which was modified through carbon paste electrode (NH(2)-FMS/CPE). NH(2)-FMS/CPE showed better performance for the electrochemical oxidation of capsaicin, when compared with bare carbon paste electrode (CPE) and mesoporous silica modified carbon paste electrode (MS/CPE). We optimized the experimental conditions influencing the determination of capsaicin. Under optimal conditions, the oxidation peak current was proportional to capsaicin concentration in the range of 0.040-0.40 ?mol L(-1)and 0.40-4.0 ?mol L(-1), when the detection limit was 0.020 ?mol L(-1) (S/N=3). The above method was successfully applied to determine capsaicin in hot pepper samples, yielding satisfactory results. The spiked recoveries were in the range of 93.1-100.7%. PMID:22417405

Ya, Yu; Mo, Leixing; Wang, Tianshun; Fan, Yegeng; Liao, Jie; Chen, Zhongliang; Manoj, Kumar Srivastava; Fang, Fengxue; Li, Chunya; Liang, Jun

2012-02-28

179

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

PubMed

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 N(2) 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. PMID:22744155

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

2012-06-28

180

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

NASA Astrophysics Data System (ADS)

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), N2 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 N2 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.

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

2010-12-01

181

Synthesis of hierarchical macro-/mesoporous solid-solution photocatalysts by a polymerization-carbonization-oxidation route: the case of Ce(0.49)Zr(0.37)Bi(0.14)O(1.93).  

PubMed

A hierarchical macro-/mesoporous Ce(0.49)Zr(0.37)Bi(0.14)O(1.93) solid-solution network has been synthesized on a large scale by means of a simple and general polymerization-carbonization-oxidation synthetic route. The as-prepared product has been characterized by SEM, XRD, TEM, BET surface area measurement, UV/Vis diffuse-reflectance spectroscopy, energy-dispersive X-ray spectroscopy (EDS), and photoelectrochemistry measurements. The photocatalytic activity of the product has been demonstrated through the photocatalytic degradation of methyl orange. Structural characterization has indicated that the hierarchical macro-/mesoporous solid-solution network not only contains numerous macropores, but also possesses an interior mesoporous structure. The mesopore size and BET surface area of the network have been measured as 2-25 nm and 140.5 m(2) g(-1), respectively. The hierarchical macro-/mesoporous solid-solution network with open and accessible pores was found to be well-preserved after calcination at 800 degrees C, indicating especially high thermal stability. Due to its high specific surface area, the synergistic effect of the coupling of macropores and mesopores, and its high crystallinity, the Ce(0.49)Zr(0.37)Bi(0.14)O(1.93) solid-solution material shows a strong structure-induced enhancement of visible-light harvest and exhibits significantly improved visible-light photocatalytic activity in the photodegradation of methyl orange compared with those of its other forms, such as mesoporous hollow spheres and bulk particles. PMID:20575115

Xi, Guangcheng; Ye, Jinhua

2010-08-01

182

Purification and characterization of double-wall carbon nanotubes synthesized by catalytic chemical vapor deposition on mesoporous silica  

Microsoft Academic Search

Double-wall carbon nanotubes (DWNTs) have been selectively synthesized by catalytic chemical vapor deposition of alcohol over Fe\\/Co loaded mesoporous silica. The as-grown carbon nanotubes are purified using a multi-step process involving heat treatment in air followed by alkali and acid treatments. The nanotubes are characterized as-grown and after each step of the purification stage by thermo-gravimetric analysis (TGA), scanning electron

P. Ramesh; T. Okazaki; T. Sugai; J. Kimura; N. Kishi; K. Sato; Y. Ozeki; H. Shinohara

2006-01-01

183

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

SciTech Connect

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.

Smith,M.; Lobo, R.

2006-01-01

184

In situ synthesis and hydrogen storage properties of PdNi alloy nanoparticles in an ordered mesoporous carbon template  

Microsoft Academic Search

Organized mesoporous carbon has been used as a nanoreactor to prepare PdNi metallic particles using an incipient wetness method starting from Pd and Ni salts. The final composite material consists of nanosized metallic particles of an alloy with composition Pd0.60Ni0.40 highly dispersed within the carbon host structure. The thermodynamic hydrogenation properties of both the PdNi-free OMC and the Pd0.60Ni0.40-OMC composite

R. Campesi; F. Cuevas; E. Leroy; M. Hirscher; R. Gadiou; C. Vix-Guterl; M. Latroche

2009-01-01

185

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

PubMed

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. PMID:23220858

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

2012-12-10

186

Fast diffusion in a room-temperature ionic liquid confined in mesoporous carbon  

SciTech Connect

We report a quasielastic neutron scattering study in the temperature range of 290 to 350 K of a room temperature ionic liquid, [bmim+][Tf2N-], in the bulk form and confined in the 8.8 2.1 nm diameter pores of a mesoporous carbon matrix. In both bulk and confined liquids, our measurements, which are sensitive to the dynamics of the hydrogen-bearing cations, detect two distinct relaxation processes related to the diffusion of the cations. We have found that the cations that do not become immobilized near the pore walls exhibit an enhanced rather than suppressed diffusivity compared to the cation diffusivity in bulk liquid. Our results provide first experimental observation of molecular diffusion in a room temperature ionic liquid in confinement which is faster than diffusion in the bulk liquid.

Mamontov, Eugene [ORNL; Wesolowski, David J [ORNL; Fulvio, Pasquale F [ORNL; Dai, Sheng [ORNL

2012-01-01

187

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

SciTech Connect

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.

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

2010-01-01

188

Ordered mesoporous materials as solid supports for rhodium-diphosphine catalysts with remarkable hydroformylation activity.  

PubMed

A rhodium-diphosphine complex based on Xantphos-type ligands was anchored on mesoporous silica SBA-15, and the material showed remarkably high catalytic activity in the hydroformylation of 1-octene, even exceeding its homogeneous analogue under certain conditions. PMID:20697633

Marras, Fabrizio; Wang, Jia; Coppens, Marc-Olivier; Reek, Joost N H

2010-08-09

189

Optimization of mesoporous carbon structures for lithium–sulfur battery applications  

SciTech Connect

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

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

190

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

SciTech Connect

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.

Cao Yulin [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Cao Jieming [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)], E-mail: jmcao@nuaa.edu.cn; Zheng Mingbo [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Liu Jinsong [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Ji Guangbin [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

2007-02-15

191

One-pot synthesis of intermetallic electrocatalysts in ordered, large-pore mesoporous carbon/silica toward formic acid oxidation.  

PubMed

This study describes the one-pot synthesis and single-cell characterization of ordered, large-pore (>30 nm) mesoporous carbon/silica (OMCS) composites with well-dispersed intermetallic PtPb nanoparticles on pore wall surfaces as anode catalysts for direct formic acid fuel cells (DFAFCs). Lab-synthesized amphiphilic diblock copolymers coassemble hydrophobic metal precursors as well as hydrophilic carbon and silica precursors. The final materials have a two-dimensional hexagonal-type structure. Uniform and large pores, in which intermetallic PtPb nanocrystals are significantly smaller than the pore size and highly dispersed, enable pore backfilling with ionomers and formation of the desired triple-phase boundary in single cells. The materials show more than 10 times higher mass activity and significantly lower onset potential for formic acid oxidation as compared with commercial Pt/C, as well as high stability due to better resistivity toward CO poisoning. In single cells, the maximum power density was higher than that of commercial Pt/C, and the stability highly improved, compared with commercial Pd/C. The results suggest that PtPb-based catalysts on large-pore OMCSs may be practically applied as real fuel cell catalysts for DFAFC. PMID:22800174

Shim, Jongmin; Lee, Jaehyuk; Ye, Youngjin; Hwang, Jongkook; Kim, Soo-Kil; Lim, Tae-Hoon; Wiesner, Ulrich; Lee, Jinwoo

2012-07-23

192

pH-responsive controlled release of antitumour-active polyoxometalate from mesoporous silica materials.  

PubMed

Two efficient pH-responsive oral delivery systems have been fabricated through a dative bonding between the amino-functionalized mesoporous silica materials, including MCM-41-type mesoporous silica nanospheres (MMSNs) and bimodal mesoporous silica microspheres (BMSMs), and an antitumour-active polyoxometalate K(8)H(2)[Ti(H(2)O)](3)SiW(9)O(34) (Ti(3)SiW(9)). The Ti(3)SiW(9) loaded in the pores of MMSNs and BMSMs are up to 23.72 wt% and 28.69 wt% at pH 6.5, respectively. Both delivery systems reveal an increase of Ti(3)SiW(9) release under mildly alkaline conditions, while zero premature release is observed under acidic and neutral conditions, making them ideal for use as a new class of colon-specific oral delivery systems. Importantly, these systems provide very promising possibilities for many medical applications that require an increase or decrease in the rate of drug release, depending on disease evolution. Upon incorporation into mesoporous silica materials, the antitumour activity of Ti(3)SiW(9) against Ls-174-T was improved from 0.8 mg mL(-1) to 0.186 and 0.102 mg mL(-1) for Ti(3)SiW(9)@MMSN-NH(2) and Ti(3)SiW(9)@BMSM-NH(2), respectively. PMID:19488446

Sun, Guoying; Chang, Yaping; Li, Siheng; Li, Qiuyu; Xu, Rui; Gu, Jianmin; Wang, Enbo

2009-04-01

193

Ordered mesoporous carbon nanoparticles with well-controlled morphologies from sphere to rod via a soft-template route.  

PubMed

A facile soft-template method is used to synthesize highly ordered mesoporous carbon nanoparticles (MCNs) with well-controlled morphology from spherical to rod-like structures. Low-molecular-weight phenolic resol is used as carbon-yielding component and triblock copolymer Pluronic F127 as pore-forming component. The morphology of nanoparticles could be tuned by well controlling the concentration of F127. The results show that rod-shaped and worm-like mesoporous carbon nanoparticles can be obtained when the concentration of F127 is set at ~12 wt.% and 9 wt.%, respectively. The spherical nanoparticles are obtained when the concentration is reduced to 6 wt.%, and their size can be adjusted by further decreasing the F127 concentration. Moreover, the highly ordered mesostructure can be readily turned from 2D hexagonal (p6m) to 3D caged cubic (Im ?3m) along with the tuning of morphologies from rod-shaped to spherical. The as-obtained MCNs exhibit large surface area (~1385 m(2)/g), high pore volume (~0.919 cm(3)/g), highly ordered mesostructure, and continuous electron transport framework. Hence, the obtained mesoporous carbon materials show excellent capacitance (~142 F/g at loading current density of 0.5A/g) in the application of supercapacitors. PMID:22542324

Li, Meng; Xue, Junmin

2012-04-11

194

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

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

195

Carbon dioxide adsorption in chemically activated carbon from sewage sludge.  

PubMed

In this work, sewage sludge was used as precursor in the production of activated carbon by means of chemical activation with KOH and NaOH. The sludge-based activated carbons were investigated for their gaseous adsorption characteristics using CO2 as adsorbate. Although both chemicals were effective in the development of the adsorption capacity, the best results were obtained with solid NaOH (SBA(T16)). Adsorption results were modeled according to the Langmuir and Freundlich models, with resulting CO2 adsorption capacities about 56 mg/g. The SBA(T16) was characterized for its surface and pore characteristics using continuous volumetric nitrogen gas adsorption and mercury porosimetry. The results informed about the mesoporous character of the SBA(T16) (average pore diameter of 56.5 angstroms). The Brunauer-Emmett-Teller (BET) surface area of the SBA(T16) was low (179 m2/g) in comparison with a commercial activated carbon (Airpel 10; 1020 m2/g) and was mainly composed of mesopores and macropores. On the other hand, the SBA(T16) adsorption capacity was higher than that of Airpel 10, which can be explained by the formation of basic surface sites in the SBA(T16) where CO2 experienced chemisorption. According to these results, it can be concluded that the use of sewage-sludge-based activated carbons is a promising option for the capture of CO2. Implications: Adsorption methods are one of the current ways to reduce CO2 emissions. Taking this into account, sewage-sludge-based activated carbons were produced to study their CO2 adsorption capacity. Specifically, chemical activation with KOH and NaOH of previously pyrolyzed sewage sludge was carried out. The results obtained show that even with a low BET surface area, the adsorption capacity of these materials was comparable to that of a commercial activated carbon. As a consequence, the use of sewage-sludge-based activated carbons is a promising option for the capture of CO2 and an interesting application for this waste. PMID:23786147

de Andrés, Juan Manuel; Orjales, Luis; Narros, Adolfo; de la Fuente, María del Mar; Encarnación Rodríguez, María

2013-05-01

196

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

PubMed

Magnetic mesoporous carbon microspheres with a yolk-shell structure (YSMMCS) have been prepared via a new in situ carbon source strategy. The material was fabricated by two shells coated onto the Fe3O4 particles; the inner dense and thick silica shell could protect the magnetic core from harsh acidic solvents as well as induce the void between the core and the outer shell for the yolk-shell structure, while the outer organosilica shell was used as the template and carbon source for in situ preparation of a carbon shell with mesoporous structure. A C18-alkyl chain was incorporated in situ as the carbon precursor efficiently, avoiding the conventional infiltration step, which was very difficult to manipulate and time-consuming with the possibility of losing the carbon precursor. The resulting yolk-shell magnetic mesoporous carbon microspheres exhibited a high surface area (273.15 m(2) g(-1)), a large pore volume (0.31 cm(3) g(-1)), and a strong magnetic response (a saturation magnetization value of 34.57 emu g(-1)). As a result of the void between the core and the outer shell and the ?-? stacking effect, adsorption capacity reached 191.64 mg g(-1) by using Rhodamine B as a standard analyte, indicating the great potential application of the material as drug carriers. Owing to the inherent hydrophobicity and high surface area, the composite material showed better performance in the enrichment of peptides than a magnetic mesoporous silica material (Fe2O3@nSiO2@mSiO2). According to the LC-MS/MS results, about 51 and 29 nonredundant peptides were identified from tryptic digests of 5 nM BSA. Additionally, taking advantage of the mesoporous structure and strong magnetic response, the material was utilized to selectively extract low abundance endogenous peptides from human serum in the presence of high abundance proteins. Based on the LC-MS/MS results, 962 endogenous peptides were obtained by 2.5 mg YSMMCS relative to 539 endogenous peptides by 5 mg Fe2O3@nSiO2@mSiO2, confirming the outstanding performance of YSMMCS in peptidome analysis. PMID:24061763

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

2013-09-23

197

Synthesis and characterisation of mesoporous carbons of large textural porosity and tunable pore size by templating mesostructured HMS silica materials  

Microsoft Academic Search

Mesostructured HMS silica materials were used as templates to fabricate mesoporous carbons with a high textural porosity. The HMS silica samples were prepared in a water-rich neutral medium by using a primary amine as structure-directing agent. Materials prepared in this way, not only have a framework-confined porosity (structural), but also a large textural porosity resulting from the interparticle spaces between

Marta Sevilla; Sonia Alvarez; Antonio B. Fuertes

2004-01-01

198

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

PubMed

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

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

2013-06-27

199

A catalytic chemical vapor deposition synthesis of double-walled carbon nanotubes over metal catalysts supported on a mesoporous material  

Microsoft Academic Search

Double-walled carbon nanotubes (DWNTs) have been synthesized by catalytic chemical vapor deposition (CCVD) over supported metal catalysts decomposed from Fe(CH3COO)2 and Co(CH3COO)2 on mesoporous silica. Bundles of tubes with relatively high percentage of DWNTs, in areas where tubular layered structures could be clearly resolved, have been observed by transmission electron microscopy (TEM). In other areas, crystal-like alignment of very uniform

Jin Zhu; Masako Yudasaka; Sumio Iijima

2003-01-01

200

Preparation and drug release behavior of temperature-responsive mesoporous carbons  

SciTech Connect

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.

Wang Xiufang [College of Pharmacy, Guangdong Pharmaceutical University, Guangzhou 510006 (China); Liu Ping [School of Chemistry and Chemical Engineering, Henan Institute of Science and Technology, Xinxiang 453003 (China); Tian Yong, E-mail: fengshoutian@hotmail.com [College of Pharmacy, Guangdong Pharmaceutical University, Guangzhou 510006 (China)

2011-06-15

201

Synthesis of multi-wall carbon nanotubes by the pyrolysis of ethanol on Fe/MCM-41 mesoporous molecular sieves  

NASA Astrophysics Data System (ADS)

Ordered hexagonal arrangement MCM-41 mesoporous molecular sieves were synthesized by the traditional hydrothermal method, and Fe-loaded MCM-41 mesoporous molecular sieves (Fe/MCM-41) were prepared by the wet impregnation method. Their mesoporous structures were testified by X-ray diffraction (XRD) and the N2 physical adsorption technique. Carbon nanotubes (CNTs) were synthesized by the chemical vapor deposition (CVD) method via the pyrolysis of ethanol at atmospheric pressure using Fe/MCM-41 as a catalytic template. The effect of different reaction temperatures ranging from 600 to 800 ?C on the formation of CNTs was investigated. The resulting carbon materials were characterized by various physicochemical techniques such as transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. The results show that multi-wall carbon nanotubes (MWCNTs) with an internal diameter of ca. 7.7 nm and an external diameter of ca. 16.9 nm were successfully obtained by the pyrolysis of ethanol at 800 ?C utilizing Fe/MCM-41 as a catalytic template.

Zhao, Qian; Li, Yanhui; Zhou, Xuping; Jiang, Tingshun; Li, Changsheng; Yin, Hengbo

2010-03-01

202

Photocatalytic Degradation of Acetaldehyde on Mesoporous TiO2: Effects of Surface Area and Crystallinity on the Photocatalytic Activity  

Microsoft Academic Search

Mesoporous TiO2 powder and films with worm-like channels were synthesized by an evaporation-induced self-assembly approach. The as-prepared samples were calcined at different temperature to investigate the effect of calcined temperature on the mesostructure and the photocatalytic activity. Acetaldehyde photodegradation in gas phase was employed to evaluate the photocatalytic activity of mesoporous TiO2. Results showed that all the calcined powder samples

Xiao-Xing Fan; Tao Yu; Li-Zhi Zhang; Xin-Yi Chen; Zhi-Gang Zou

2007-01-01

203

Template synthesis and characterization of mesoporous zeolites  

Microsoft Academic Search

Well-crystalline ZSM-5 and zeolite Y having uniform mesopores were synthesized with template route method using carbon aerogels of different mesoporosities. These mesoporous zeolites were characterized with X-ray diffraction, FT-IR spectroscopy, field emission scanning electron microscopy, and N2 adsorption. ZSM-5 having mesopore volume of 0.2–1cm3g?1 was obtained. Mesoporous ZSM-5 synthesized by heating at 423K for 96h was well-crystalline, which had mesopores

Yousheng Tao; H Kanoh; Y Hanzawa; K Kaneko

2004-01-01

204

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

205

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

PubMed

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

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

2012-11-20

206

A nano-fibrillated mesoporous carbon as an effective support for palladium nanoparticles in the aerobic oxidation of alcohols "on pure water".  

PubMed

A novel nano-fibrillated mesoporous carbon (IFMC) was successfully prepared via carbonization of the ionic liquid 1-methyl-3-phenethyl-1H-imidazolium hydrogen sulfate (1) in the presence of SBA-15. The material was shown to be an efficient and unique support for the palladium nanoparticle (PdNP) catalyst Pd@IFMC (2) in aerobic oxidation of heterocyclic, benzylic, and heteroatom containing alcohols on pure water at temperatures as low as 40 °C for the first time and giving almost consistent activities and selectivities within more than six reaction runs. The catalyst has also been employed as an effective catalyst for the selective oxidation of aliphatic and allylic alcohols at 70-80 °C. The materials were characterized by X-ray photoelectron spectroscopy (XPS), N(2) adsorption-desorption analysis, transmission electron microscopy (TEM), and electron tomography (ET). Our compelling XPS and ET studies showed that higher activity of 2 compared to Pd@CMK-3 and Pd/C in the aerobic oxidation of alcohols on water might be due to the presence of nitrogen functionalities inside the carbon structure and also the fibrous nature of our materials. The presence of a nitrogen heteroatom in the carboneous framework might also be responsible for the relatively uniform and nearly atomic-scale distribution of PdNPs throughout the mesoporous structure and the inhibition of Pd agglomeration during the reaction, resulting in high durability, high stability, and recycling characteristics of 2. This effect was clearly confirmed by comparing the TEM images of the recovered 2 and Pd@CMK-3. PMID:22707318

Karimi, Babak; Behzadnia, Hesam; Bostina, Mihnea; Vali, Hojatollah

2012-06-15

207

Mesoporous MgTa2O6 thin films with enhanced photocatalytic activity: On the interplay between crystallinity and mesostructure  

PubMed Central

Summary Ordered mesoporous, crystalline MgTa2O6 thin films with a mesoscopic nanoarchitecture were synthesized by evaporation-induced self-assembly (EISA) in combination with a sol–gel procedure. Utilization of novel templates, namely the block copolymers KLE (poly(ethylene-co-butylene)-b-poly(ethylene oxide)) and PIB6000 (CH3C(CH3)2(CH2C(CH3)2)107CH2C(CH3)2C6H4O(CH2CH2O)100H), was the key to achieving a stable ordered mesoporous structure even upon crystallization of MgTa2O6 within the mesopore walls. The effect of the calcination temperature on the ability of the mesoporous films to assist the photodegradation of rhodamine B in water was studied. As a result, two maxima in the photocatalytic activity were identified in the calcination temperature range of 550–850 °C, peaking at 700 °C and 790 °C, and the origin of this was investigated by using temperature-dependent X-ray scattering. Optimal activity was obtained when the mesoporous film was heated to 790 °C; at this temperature, crystallinity was significantly high, with MgTa2O6 nanocrystals of 1.6 nm in size (averaged over all reflections), and an ordered mesoporous structure was maintained. When considering the turnover frequency of such photocatalysts, the optimized activity of the present nanoarchitectured MgTa2O6 thin film was ca. four times that of analogous anatase TiO2 films with ordered mesopores. Our study demonstrated that high crystallinity and well-developed mesoporosity have to be achieved in order to optimize the physicochemical performance of mesoporous metal-oxide films.

Wu, Jin-Ming; Djerdj, Igor; von Graberg, Till

2012-01-01

208

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

SciTech Connect

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.

Song, Lingyan; Feng, Dan; Fredin, Nathaniel J.; Yager, Kevin G.; Jones, Ronald L.; Wu, Quanyan; Zhao, Dongyuan; Vogt, Bryan D. (On Semi); (AZU); (NIST); (Fudan)

2010-06-22

209

High capacity magnetic mesoporous carbon-cobalt composite adsorbents for removal of methylene green from aqueous solutions.  

PubMed

Mesoporous carbons containing cobalt nanoparticles are synthesized by tri-or quad-constituent self assembly of Pluronic F127, phenol-formaldehyde oligomer (resol), cobalt acetylacetonate (acac), and optionally tetraethyl orthosilicate (TEOS, optional). Upon pyrolysis in N(2) atmosphere, the resol provides sufficient carbon yield to maintain the ordered structure, while decomposition of the Co(acac) yields cobalt nanoparticles. To provide increased surface area, the dispersed silicate from condensation of TEOS can be etched after carbonization to yield micropores, Without silica templated micropores, the surface area decreases as the cobalt content increases, but there is a concurrent increase in the volume-average pore diameter (BHJ) and a dramatic increase in the adsorption capacity of methylene green with the equilibrium adsorption capacity from 2 to 90 mg/g with increasing Co content. Moreover, the surface area and pore size of mesoporous composites can be dramatically increased by addition of TEOS and subsequent etching. These composites exhibit extremely high adsorption capacity up to 1151 mg/g, which also increases with increases in the Co content. Additionally, the inclusion of cobalt nanoparticles provides magnetic separation from aqueous suspension. The in situ synthesis of the Co nanoparticles yields to a carbon shell that can partially protect the Co from leaching in acidic media; after 96 h in 2 M HCl, the powders remain magnetic. PMID:22975394

Dai, Mingzhi; Vogt, Bryan D

2012-07-06

210

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

211

MoO2-ordered mesoporous carbon nanocomposite as an anode material for lithium-ion batteries.  

PubMed

In the present work, the nanocomposite of MoO2-ordered mesoporous carbon (MoO2-OMC) was synthesized for the first time using a carbon thermal reduction route and the mesoporous carbon as the nanoreactor. The synthesized nanocomposite was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), N2 adsorption-desorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) measurements. Furthermore, this nanocomposite was used as an anode material for Li-ion intercalation and exhibited large reversible capacity, high rate performance, and good cycling stability. For instance, a high reversible capacity of 689 mAh g(-1) can remain after 50 cycles at a current density of 50 mA g(-1). It is worth mentioning that the MoO2-OMC nanocomposite electrode can attain a high reversible capacity of 401 mAh g(-1) at a current density as high as 2 A g(-1). These results might be due to the intrinsic characteristics of nanocomposite, which offered a better accommodation of the strain and volume changes and a shorter path for Li-ion and electron transport, leading to the improved capacity and enhanced rate capability. PMID:23438299

Zeng, Lingxing; Zheng, Cheng; Deng, Cuilin; Ding, Xiaokun; Wei, Mingdeng

2013-03-07

212

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

SciTech Connect

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.

Rother, Gernot [ORNL; Krukowski, Elizabeth G [ORNL; Wallacher, Dirk [Helmholtz-Zentrum Berlin; Grimm, Nico [Helmholtz-Zentrum Berlin; Bodnar, Robert J [ORNL; Cole, David [Ohio State University

2012-01-01

213

Activated carbon material  

DOEpatents

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.

Evans, A. Gary (North Augusta, SC)

1978-01-01

214

Robust conductive mesoporous carbon?silica composite films with highly ordered and oriented orthorhombic structures from triblock-copolymer template co-assembly  

SciTech Connect

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.

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. (AZU)

2012-07-11

215

Multiple constituents co-assembly of ordered mesoporous Al2O3-SiO2-carbon nanocomposites.  

PubMed

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

Wang, Wei; Xue, Huanhuan; Feng, Cuimiao; Kong, Lina; Zhao, Qingfei; Wan, Ying

2013-02-01

216

Surface studies of novel hydrophobic active carbons  

NASA Astrophysics Data System (ADS)

The efficient adsorption of toxic organic species from humid airstreams by active carbons is impeded by the competitive adsorption of water vapour which, at low values of p/ ps, occurs at specific (polar) adsorption sites located at the edges of the carbon layer-planes and at in-plane defects. At higher pressures, adsorption in micropores and mesopores also occurs. The concentration of polar adsorption sites therefore determines the hydrophilicity of the carbon structure and their accelerated formation, by exposure to air and water vapour, is also responsible for the 'ageing' of active carbons. Overall, the adsorption of water reduces the volume of porosity available for the adsorption of target species and the hydrophilic nature of active carbons is recognized as a major barrier to their effective use in many applications. We present here results for the adsorption of nitrogen, organic and water vapours by a hydrophobic respirator granular active carbon produced by the thermal treatment of a base carbon, to desorb polar oxygen groups, followed by use of a plasma enhanced chemical vapour deposition (PECVD) treatment to apply a hydrophobic, fluorine containing, surface nanolayer. We show that at equivalent %RH values the treated carbon adsorbs significantly less water compared to an untreated (control) carbon and that the treatment does not reduce the levels of open porosity or impede the adsorption of a range of organic vapours at ambient temperatures. Preliminary evidence for the presence, after treatment, of constrictions at pore entrances which act as molecular gates is also presented. The treated carbon (after ageing for 6 weeks at 80%RH) is shown to have greater adsorptivity than an untreated base carbon toward hexane present in a humid (80%RH) airstream. This results in a 39% increase in break-through time. These hydrophobic properties persist one year after manufacture. The mechanism leading to the modified water adsorption properties is the partial desorption of polar oxygen sites followed by deposition at the external carbon surfaces of hydrophobic plasma polymer species. This reduces the polar surface free energy of the carbon and hence the amount of water adsorption occurring by the primary mechanism. This in turn retards the diffusion of water molecules into the micropores and leads to lower adsorption volumes at higher pressures.

Bradley, Robert H.; Smith, Martin W.; Andreu, Aurik; Falco, Maurizio

2011-01-01

217

Template-free synthesis of mesoporous N-doped SrTiO3 perovskite with high visible-light-driven photocatalytic activity.  

PubMed

An effective, template-free synthesis methodology has been developed for preparing mesoporous nitrogen-doped SrTiO(3) (meso-STON) using glycine as both a nitrogen source and a mesopore creator. The N-doping, large surface area and developed porosity endow meso-STON with excellent activity in visible-light-responsive photodegradation of organic dyes. PMID:22814856

Zou, Fei; Jiang, Zheng; Qin, Xiaoqin; Zhao, Yongxiang; Jiang, Luyun; Zhi, Jinfang; Xiao, Tiancun; Edwards, Peter P

2012-07-20

218

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

PubMed

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

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

2012-07-26

219

Uniform dispersion of 1?:?1 PtRu nanoparticles in ordered mesoporous carbon for improved methanol oxidation.  

PubMed

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

Li, Fujun; Chan, Kwong-Yu; Yung, Hoi; Yang, Chunzhen; Ting, Siu Wa

2013-08-28

220

In Situ intercalating expandable graphite for mesoporous carbon/graphite nanosheet composites as high-performance supercapacitor electrodes.  

PubMed

Mesoporous-carbon-coated graphite nanosheet (GNS@MC) composites have been synthesized by the intercalation of resol prepolymer into the interlayers of expandable graphite (EG) under vacuum-assisted conditions, followed by the exfoliation of EG through in situ polymerization, the growth of resol under hydrothermal conditions, and carbonization under Ar. The GNS@MC composites exhibit enhanced capacitive performance compared to mesoporous carbon (MC), microwaved EG after thermal treatment (T-EG), and the physical mixture of MC and T-EG (MC+T-EG). In particular, the GNS@MC-35-800 composite carbonized at 800 °C, which has a graphite-nanosheet content of 35 % and a Brunauer-Emmett-Teller surface area (S(BET) ) of 432.3 m(2) ?g(-1) , exhibits the highest capacitance of 203 F g(-1) at 1 A g(-1) in 6 M KOH electrolyte. Furthermore, the GNS@MC-35-800 composite exhibits a good cyclic stability with 95 % capacitance retention and a high columbic efficiency of 99 % after 5000 cycles. The energy density of the symmetric supercapacitor GNS@MC-35-800/GNS@MC-35-800 achieved was as high as 11.5 Wh kg(-1) at a high power density of 10 kW kg(-1) . This good performance is attributable to the GNSs in the GNS@MC composite facilitating electron transport owing to its excellent conductivity; moreover, the MC in GNS@MC favors the rapid diffusion of ions by providing low-resistance pathways. The GNS@MC composite may find application in high-performance energy storage and conversion devices. PMID:23081877

Wang, Lei; Mu, Guang; Tian, Chungui; Sun, Li; Zhou, Wei; Tan, Taixing; Fu, Honggang

2012-10-18

221

Promoting immobilization and catalytic activity of horseradish peroxidase on mesoporous silica through template micelles.  

PubMed

New concept on the promotion of immobilization and catalytic activity of enzyme on mesoporous silica through template micelles is proposed and realized in this paper. Proper P123 templates are controllable retained in the as-synthesized SBA-15, not only to anchor the horseradish peroxidase (HRP) guest, but also to establish the crowding-like microenvironment around the enzyme. The influence of retaining templates on the pore structure of SBA-15, immobilization, and catalytic activity of HRP is studied, and the possible process of template removal is proposed. Ethanol refluxing of 6 h is conformable to prepare the optimal mesoporous support characterized with the retained templates of about 8%. With the assistance of retained templates in SBA-15, up to 49 mg g(-1) of HRP can be immobilized, 100% more than that on calcined SBA-15. Furthermore, the thermal stability, the resistance of pH variation and denaturing agent urea, and the recycle usage of HRP immobilized are obviously elevated, paving a novel and low-cost route to develop enzyme catalysts. PMID:22507401

Wan, Mi Mi; Lin, Wei Gang; Gao, Ling; Gu, Hui Cheng; Zhu, Jian Hua

2012-03-28

222

Bottom-Up Catalytic Approach towards Nitrogen-Enriched Mesoporous Carbons/Sulfur Composites for Superior Li-S Cathodes.  

PubMed

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

Sun, Fugen; Wang, Jitong; Chen, Huichao; Qiao, Wenming; Ling, Licheng; Long, Donghui

2013-10-02

223

Bottom-Up Catalytic Approach towards Nitrogen-Enriched Mesoporous Carbons/Sulfur Composites for Superior Li-S Cathodes  

PubMed Central

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.

Sun, Fugen; Wang, Jitong; Chen, Huichao; Qiao, Wenming; Ling, Licheng; Long, Donghui

2013-01-01

224

Layer-by-layer self-assembled mesoporous PEDOT-PSS and carbon black hybrid films for platinum free dye-sensitized-solar-cell counter electrodes.  

PubMed

A thin film of poly(3,4-ethylenedioxythiophene)-poly(4-styrenesulfonic acid) (PEDOT-PSS), which is an alternative cathodic catalyst for Pt in dye-sensitized solar cells, was prepared using the layer-by-layer self-assembly method (LbL). The film is highly adhesive to the substrate and has a controllable thickness. Therefore, the PEDOT-PSS film prepared using LbL is expected have high performance and durability as a counter electrode. Moreover, when carbon black was added to the PEDOT-PSS solution, highly mesoporous PEDOT-PSS and carbon black hybrid films were obtained. These films showed high cathodic activity. In this study, we investigated the change in morphology in the obtained film with increasing carbon black content, and the influence of the porosity and thickness on the performance of the cells. In this study, a Pt-free counter electrode with performance similar to that of Pt-based counter electrodes was successfully fabricated. The achieved efficiency of 4.71% was only a factor of 8% lower than that of the cell using conventional thermally deposited Pt on fluorine-doped tin oxide glass counter electrodes. PMID:21430326

Kitamura, Koji; Shiratori, Seimei

2011-03-23

225

Mesoporous anatase TiO2 nanocups with plasmonic metal decoration for highly active visible-light photocatalysis.  

PubMed

This communication describes a method for facile synthesis of mesoporous anatase TiO2 nanocup crystals. The novel cuplike morphology of TiO2 decorated with gold (Au-TiO2) yields remarkably high photocatalytic activity for degradation of methylene blue under visible light irradiation. PMID:23598799

Lu, Jianwei; Zhang, Peng; Li, Ang; Su, Fengli; Wang, Tuo; Liu, Yuan; Gong, Jinlong

2013-04-19

226

Synthesis of Co-containing mesoporous carbon foams using a new cobalt-oxo cluster as a precursor  

SciTech Connect

A novel trinuclear cobalt-oxo cluster 2[Co{sub 3}O(Ac){sub 6}(H{sub 2}O){sub 3}]{center_dot}H{sub 2}O (Co-OXO) has been obtained and characterized by X-ray single-crystal diffraction and elemental analysis. The structure of Co-OXO displays 3D supramolecular networks through hydrogen bonds and generates boron nitride (bnn) topology. Co-OXO was further used as a precursor to synthesize Co-containing mesoporous carbon foams (Co-MCFs), which exhibit highly ordered mesostructure with specific surface area of 614 m{sup 2} g{sup -1} and uniform pore size of 2.7 nm. Charge-discharge tests show that the specific discharge capacitance of Co-MCFs is 7% higher than that of the MCFs at the current density of 100 mA g{sup -1}, and 26% higher than that of MCFs at the current density of 3 A g{sup -1}. The electrochemical behaviors of Co-MCFs are obviously improved due to the improved wettability, increased graphitization degree and the pseudo-capacitance through additional faradic reactions arising from cobalt. - Graphical Abstract: A new trinuclear cobalt-oxo cluster, 2[Co{sub 3}O(Ac){sub 6}(H{sub 2}O){sub 3}]{center_dot}H{sub 2}O (1), was obtained and further used as a precursor to synthesize Co-containing mesoporous carbon foams (Co-MCFs) which exhibit improved electrochemical behaviors. Highlights: Black-Right-Pointing-Pointer A new trinuclear cobalt-oxo cluster (1) were obtained. Black-Right-Pointing-Pointer 1 is joined by hydrogen bonds to construct a 3D structure showing bnn topology. Black-Right-Pointing-Pointer 1 was further used to obtain Co-containing mesoporous carbon foams (Co-MCFs). Black-Right-Pointing-Pointer Co-MCFs exhibit highly ordered mesostructure and uniform pore sizes. Black-Right-Pointing-Pointer Electrochemical behaviors of Co-MCFs are obviously improved compared with pure MCFs.

Lv Yaokang [Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Feng Yunlong [Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004 (China); Gan Lihua, E-mail: ganlh@tongji.edu.cn [Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Liu Mingxian; Xu Liang; Liu Cao; Zheng Haowen; Li Jie [Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai 200092 (China)

2012-01-15

227

In-Situ Observation of Solid Electrolyte Interphase Formation in Ordered Mesoporous Hard Carbon by Small-Angle Neutron Scattering  

SciTech Connect

The aim of this work was to better understand the electrochemical processes occurring during the cycling of a lithium-ion half-cell containing ordered mesoporous hard carbon using time-resolved in situ small-angle neutron scattering (SANS). Utilizing electrolytes containing mixtures of deuterated (2H) and non-deuterated (1H) carbonates, we have addressed the challenging task of monitoring the formation and evolution of the solid-electrolyte interphase (SEI) layer. An evolution occurs in the SEI layer during discharge from a composition dominated by a higher scattering length density (SLD) lithium salt, to a lower SLD lithium salt for the ethylene carbonate/dimethyl carbonate (EC/DMC) mixture employed. By comparing half-cells containing different solvent deuteration levels, we show that it is possible to observe both SEI formation and lithium intercalation occurring concurrently at the low voltage region in which lithium intercalates into the hard carbon. These results demonstrate that SANS can be employed to monitor complicated electrochemical processes occurring in rechargeable batteries, in a manner that simultaneously provides information on the composition and microstructure of the electrode.

Bridges, Craig A [ORNL; Paranthaman, Mariappan Parans [ORNL; Sun, Xiao-Guang [ORNL; Zhao, Jinkui [ORNL; Dai, Sheng [ORNL

2012-01-01

228

Amine-modified ordered mesoporous silica: Effect of pore size on carbon dioxide capture  

Microsoft Academic Search

Three mesoporous silica materials with different pore sizes (33Å for small pore size MCM-41; 38Å for SBA-12; 71Å for large pore size SBA-15) and pore connectivity (2D for MCM-41 and SBA-15-type materials; 3D for SBA-12 material) were prepared and functionalized with aminopropyl (AP) ligands by post-synthesis treatment. The materials were characterized by small angle X-ray scattering (SAXS), transmission electron microscopy

V. Zele?ák; M. Badani?ová; D. Halamová; J. ?ejka; A. Zukal; N. Murafa; G. Goerigk

2008-01-01

229

Modeling carbon dioxide adsorption on polyethylenimine-functionalized TUD-1 mesoporous silica  

Microsoft Academic Search

Samples of porous, foam-like TUD (Technische Universität Delft)-1 mesoporous silica, were functionalized with polyethylenimine and were used as a substrate for CO2 adsorption. Produced solids were characterized by means of electron microscopy, thermogravimetric analysis, and N2 adsorption\\/desorption at 77K, in order to prove that polymer chains efficiently filled the pores of functionalized samples. CO2 adsorption isotherms on polyethylenimine-containing TUD-1 were

Nicola Gargiulo; Domenico Caputo; Francesco Pepe

2011-01-01

230

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

PubMed

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

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

2013-06-11

231

Mesoporous silica-encapsulated gold nanoparticles as artificial enzymes for self-activated cascade catalysis.  

PubMed

A significant challenge in chemistry is to create synthetic structures that mimic the complexity and function of natural systems. Here, a self-activated, enzyme-mimetic catalytic cascade has been realized by utilizing expanded mesoporous silica-encapsulated gold nanoparticles (EMSN-AuNPs) as both glucose oxidase- and peroxidase-like artificial enzymes. Specifically, EMSN helps the formation of a high degree of very small and well-dispersed AuNPs, which exhibit an extraordinarily stability and dual enzyme-like activities. Inspired by these unique and attractive properties, we further piece them together into a self-organized artificial cascade reaction, which is usually completed by the oxidase-peroxidase coupled enzyme system. Our finding may pave the way to use matrix as the structural component for the design and development of biomimetic catalysts and to apply enzyme mimics for realizing higher functions. PMID:23352119

Lin, Youhui; Li, Zhenhua; Chen, Zhaowei; Ren, Jinsong; Qu, Xiaogang

2013-01-23

232

Effects of pore structure and electrolyte on the capacitive characteristics of steam- and KOH-activated carbons for supercapacitors  

Microsoft Academic Search

Four kinds of activated carbons (denoted as ACs) with specific surface area of ca. 1050m2g?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 N2 adsorption isotherms. The amount of mesopores within KOH-activated carbons ranged from 9.2 to 15.3%

Feng-Chin Wu; Ru-Ling Tseng; Chi-Chang Hu; Chen-Ching Wang

2005-01-01

233

Properties of pyrolytic chars and activated carbons derived from pilot-scale pyrolysis of used tires.  

PubMed

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

Li, S Q; Yao, Q; Wen, S E; Chi, Y; Yan, J H

2005-09-01

234

Ultrasensitive electrochemical sensing of the anticancer drug tirapazamine using an ordered mesoporous carbon modified pyrolytic graphite electrode.  

PubMed

A new ordered mesoporous carbon (OMC) modified pyrolytic graphite electrode (PGE) was prepared to investigate electrochemical behavior of the anticancer drug tirapazamine (TPZ). Compared to the bare PGE, the modified electrode showed an excellent electrochemical response to TPZ. The anodic peak current (I(pa)) of TPZ at the OMC/PGE is 180-fold higher than that of the bare PGE. The I(pa) is proportional with TPZ concentration in the range of 5.0 x 10(-11) to 1.5 x 10(-5) mol L(-1). The linear regression equations are I(pa) (microA)=0.0000044+16.928C(TPZ) (micromolL(-1)), with a detection limit (S/N=3) of 2.0 x 10(-11) mol L(-1). This proposed method can be potentially used for ultrasensitive electrochemical sensing of TPZ in physiological condition. PMID:19450968

Hu, Guangzhi; Guo, Yong; Shao, Shijun

2009-05-03

235

Effects of pyrolysis conditions on the porous structure construction of mesoporous charred carbon from used cigarette filters  

NASA Astrophysics Data System (ADS)

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.

Masoudi Soltani, Salman; Yazdi, Sara Kazemi; Hosseini, Soraya

2013-05-01

236

Simultaneous Determination of Copper, Lead, and Cadmium at Hexagonal Mesoporous Silica Immobilized Quercetin Modified Carbon Paste Electrode  

PubMed Central

A new method was developed for simultaneous determination of copper, lead, and cadmium, based on their voltammetric response at a carbon paste electrode modified with hexagonal mesoporous silica (HMS) immobilized quercetin (HMS-Qu/CPE). Compared with quercetin modified carbon paste electrode (Qu/CPE) and quercetin ionic liquid modified carbon paste electrode (Qu-IL/CPE), the HMS-Qu/CPE exhibited improved selectivity and high sensitivity toward the detection of copper, lead, and cadmium. The properties of the HMS-Qu/CPE in 0.1?M HCOONa-HCl buffer solution (pH4.7) were investigated by adsorptive stripping voltammetry (ASV) and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of copper, lead, and cadmium at the modified electrodes and factors affecting the preconcentration procedures were also investigated. Detection limits of 5.0, 0.8, 1.0?nM for copper, lead, and cadmium were obtained, respectively. The method is simple, fast, sensitive, and selective, and is successfully applied to soil sample.

Xia, Fangquan; Zhang, Xin; Zhou, Changli; Sun, Danzi; Dong, Yanmin; Liu, Zhen

2010-01-01

237

Characterization of the pore structure of three-dimensionally ordered mesoporous carbons using high resolution gas sorption.  

PubMed

The use of colloidal crystals with various primary particle sizes as templates leads to the formation of three-dimensionally ordered mesoporous (3DOm) carbons containing spherical pores with tailorable pore size and extremely high pore volumes. We present a comprehensive structural characterization of these novel carbons by using nitrogen (77.4 K) and argon (87.3 K) adsorption coupled with the application of novel, dedicated quenched solid density functional theory (QSDFT) methods which assume correctly the underlying spherical pore geometry and also the underlying adsorption mechanism. The observed adsorption isotherms are of Type IV with Type H1-like hysteresis, despite the fact that pore blocking affects the position of the desorption branch. This follows also from detailed, advanced scanning hysteresis experiments which not only allow one to identify the underlying mechanisms of hysteresis, but also provide complementary information about the texture of these unique porous materials. This work addresses the problem of pore size analysis of novel, ordered porous carbons and highlights the importance of hysteresis scanning experiments for textural analysis of the pore network. PMID:22853806

Cychosz, Katie A; Guo, Xuefeng; Fan, Wei; Cimino, Richard; Gor, Gennady Yu; Tsapatsis, Michael; Neimark, Alexander V; Thommes, Matthias

2012-08-14

238

Properties of Pyrolytic Chars and Activated Carbons Derived from Pilot-Scale Pyrolysis of Used Tires  

Microsoft Academic Search

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. Meso-porous 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

S.-Q. Li; Q. Yao; S.-E. Wen; Y. Chi; J.-H. Yan

2005-01-01

239

Adsorption characterisation of different volatile organic compounds over alumina, zeolites and activated carbon using inverse gas chromatography  

Microsoft Academic Search

Adsorption parameters (enthalpy of adsorption, free energy of adsorption) of several alkanes, cyclic hydrocarbons, aromatic hydrocarbons and chlorinated compounds on different adsorbents (alumina, zeolites 13X and 5A, and activated carbon) were determined by inverse gas chromatography. Dispersive surface energy interaction and specific interaction parameters were determined for each solute–adsorbent system. It was found that mesoporous alumina presents lower enthalpy of

Eva Díaz; Salvador Ordóñez; Aurelio Vega; José Coca

2004-01-01

240

Synthesis and photocatalytic activity for water-splitting reaction of nanocrystalline mesoporous titania prepared by hydrothermal method  

SciTech Connect

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)

Jitputti, Jaturong [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan); Pavasupree, Sorapong [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan); Department of Materials and Metallurgical Engineering, Faculty of Engineering, Rajamangala University of Technology Thanyaburi, Klong 6, Pathumthani, 12110 (Thailand); Suzuki, Yoshikazu [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan); Yoshikawa, Susumu [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)], E-mail: s-yoshi@iae.kyoto-u.ac.jp

2007-05-15

241

Synthesis and photocatalytic activity for water-splitting reaction of nanocrystalline mesoporous titania prepared by hydrothermal method  

Microsoft Academic Search

Nanocrystalline mesoporous TiO2 was synthesized by hydrothermal method using titanium butoxide as starting material. XRD, SEM, and TEM analyses revealed that the synthesized TiO2 had anatase structure with crystalline size of about 8nm. Moreover, the synthesized titania possessed a narrow pore size distribution with average pore diameter and high specific surface area of 215m2\\/g. The photocatalytic activity of synthesized TiO2

Jaturong Jitputti; Sorapong Pavasupree; Yoshikazu Suzuki; Susumu Yoshikawa

2007-01-01

242

Visible-light photocatalytic activity of gold nanoparticles supported on template-synthesized mesoporous titania for the decontamination of the chemical warfare agent Soman  

Microsoft Academic Search

Mesoporous titania containing gold nanoparticles has been found to be an efficient photocatalyst for the visible-light decontamination of Soman. This contrasts with the complete lack of visible-light activity of analogous mesoporous titania sample without containing Au and is attributed to light absorption by the gold nanoparticles surface plasmon band. The possibility that Soman degradation occurs by light-induced heating is unlikely

Mercedes Alvaro; Bogdan Cojocaru; Adel A. Ismail; Nicoleta Petrea; Belen Ferrer; Farid A. Harraz; Vasile I. Parvulescu; Hermenegildo Garcia

2010-01-01

243

Granular activated carbons from palm nut shells for gold di-cyanide adsorption  

NASA Astrophysics Data System (ADS)

Granular activated carbons were produced from palm nut shells by physical activation with steam. The proximate analysis of palm nut shells was investigated by thermogravimetric analysis, and the adsorption capacity of the activated carbons, produced as a result of shell pyrolysis at 600°C followed by steam activation at 900°C in varying activation times, was evaluated using nitrogen adsorption at 77 K. Applicability of the activated carbons for gold dicyanide adsorption was also investigated. Increasing the activation hold time with the attendant increase in the degree of carbon burn-off results in a progressive increase in the surface area of the activated carbons, reaching a value of 903.1 m2/g after activation for 6 h. The volumes of total pores, micropores, and mesopores in the activated carbons also increase progressively with the increasing degree of carbon burn-off, resulting from increasing the activation hold time. The gold di-cyanide adsorption of the activated carbons increases with the rise of pore volume of the activated carbons. The gold di-cyanide adsorption of palm nut shell activated carbon obtained after 6-h activation at 900°C is superior to that of a commercial activated carbon used for gold di-cyanide adsorption.

Buah, William K.; Williams, Paul T.

2013-02-01

244

Activated carbon from vetiver roots: gas and liquid adsorption studies.  

PubMed

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

Gaspard, S; Altenor, S; Dawson, E A; Barnes, P A; Ouensanga, A

2006-10-07

245

Preparation of lanthana-doped titania nanoparticles with anatase mesoporous walls and high photocatalytic activity  

Microsoft Academic Search

Lanthana-doped mesoporous TiO2 nanoparticles with high specific surface area and thermal stable anatase wall was synthesized via hydrothermal process by using cetyltrimethylammonium bromide (CTAB) as surfactant-directing agent and pore-forming agent. The resulting materials were characterized by XRD, FESEM, TEM, FT-IR spectroscopy, and nitrogen adsorption. The as-synthesized mesoporous doped TiO2 nanoparticles have mean diameter of 20nm with mean pore size of

Tianyou Peng; De Zhao; Haibo Song; Chunhua Yan

2005-01-01

246

Electrochemical determination of toxic ractopamine at an ordered mesoporous carbon modified electrode.  

PubMed

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

Yang, Xiao; Feng, Bo; Yang, Peng; Ding, Yonglan; Chen, Yi; Fei, Junjie

2013-09-03

247

Fabrication of multiwalled carbon nanotubes in the channels of iron loaded three dimensional mesoporous material by catalytic chemical vapour deposition technique  

NASA Astrophysics Data System (ADS)

The growth of multiwalled carbon nanotubes (MWNTs) was successfully achieved in the channels of three dimensional (3D) iron loaded mesoporous matrices (KIT-6) by employing catalytic chemical vapour deposition (CCVD) technique. The synthesised MWNTs, which were characterised by SEM, TEM and Raman spectroscopy, consist of thick graphene layers of about 10 nm composed of 29 graphene sheets with inner and outer diameter of ˜17 nm and ˜37 nm, respectively. The Raman spectrum showed the formation of well-graphitised MWNTs with significantly higher IG/ ID ratio of 1.47 compared to commercial MWNTs. Comparatively, 2 wt% Fe loaded KIT-6 material produced a better yield of 91%, which is also highest compared with the report of MWNTs synthesis using mesoporous materials reported so far.

Somanathan, T.; Gokulakrishnan, N.; Chandrasekar, G.; Pandurangan, A.

2011-01-01

248

Activated carbons developed from surplus sewage sludge for the removal of dyes from dilute aqueous solutions  

Microsoft Academic Search

Surplus biological sludge from wastewater treatment plants was pyrolysed at 700°C in the presence of H2SO4. Sludge-based (SB) activated carbon (AC) was mainly mesoporous in nature, with a surface area of 253m2\\/g and an average pore diameter of 2.3nm. Chemviron GW, an AC commercial reference, was mainly microporous with a surface area of 1026m2\\/g and an average diameter of 1.8nm.

Maria J. Martin; Adriana Artola; M. Dolors Balaguer; Miquel Rigola

2003-01-01

249

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

Microsoft Academic Search

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

Jinchuan Xie; Xuhui Wang; Jiyong Deng; Lixing Zhang

2005-01-01

250

Activation of snap-top capped mesoporous silica nanocontainers using two near-infrared photons.  

PubMed

Photoactivation of "snap-top" stoppers over the pore openings of mesoporous silica nanoparticles releases intact cargo molecules from the pores. The on-command release can be stimulated by either one UV photon or two coherent near-IR photons. Two-photon activation is particularly desirable for use in biological systems because it enables good tissue penetration and precise spatial control. Stoppers were assembled by first binding photolabile coumarin-based molecules to the nanoparticle surface. Then, after the particles were loaded with cargo, bulky ?-cyclodextrin (CD) molecules were noncovalently associated with the substituted coumarin molecule, blocking the pores and preventing the cargo from escaping. One-photon excitation at 376 nm or two-photon excitation at 800 nm cleaves the bond holding the coumarin to the nanopore, releasing both the CD cap and the cargo. The dynamics of both the cleavage of the cap and the cargo release was monitored using fluorescence spectroscopy. This system traps intact cargo molecules without the necessity of chemical modification, releases them with tissue-penetrating near-IR light, and has possible applications in photostimulated drug delivery. PMID:24015927

Guardado-Alvarez, Tania M; Sudha Devi, Lekshmi; Russell, Melissa M; Schwartz, Benjamin J; Zink, Jeffrey I

2013-09-17

251

Activated carbon from municipal waste  

Microsoft Academic Search

A refuse derived fuel (RDF) was carbonized by partial combustion at 623 K and the carbonized RDF (cRDF) was steam-activated at 1123 K. The cRDF was also treated by 3.3 or 5.2 N nitric acid at a boiling temperature for 3 h prior to the steam-activation. Porous properties of the activated carbons prepared were determined by the nitrogen adsorption method.

S Nagano; H Tamon; T Adzumi; K Nakagawa; T Suzuki

2000-01-01

252

Probing mechanisms for enzymatic activity enhancement of organophosphorus hydrolase in functionalized mesoporous silica.  

PubMed

We have previously reported that organophosphorus hydrolase (OPH) can be spontaneously entrapped in functionalized mesoporous silica (FMS) with HOOC- as the functional groups and the entrapped OPH in HOOC-FMS showed enhanced enzyme specific activity. This work is to study the mechanisms that why OPH entrapped in FMS displayed the enhanced activity in views of OPH-FMS interactions using spectroscopic methods. The circular dichroism (CD) spectra show that, comparing to the secondary structure of OPH free in solution, OPH in HOOC-FMS displayed increased alpha-helix/beta-strand transition of OPH with increased OPH loading density. The fluorescence emission spectra of Trp residues were used to assess the tertiary structural changes of the enzyme. There was a 42% increase in fluorescence. This is in agreement with the fact that the fluorescence intensity of OPH was increased accompanying with the increased OPH activity when decreasing urea concentrations in solution. The steady-state anisotropy was increased after OPH entrapping in HOOC-FMS comparing to the free OPH in solution, indicating that protein mobility was reduced upon entrapment. The solvent accessibility of Trp residues of OPH was probed by using acrylamide as a collisional quencher. Trp residues of OPH-FMS had less solvent exposure comparing with free OPH in solution due to its electrostatical binding to HOOC-FMS thereby displaying the increased fluorescence intensity. These results suggest the interactions of OPH with HOOC-FMS resulted in the protein immobilization and a favorable conformational change for OPH in the crowded confinement space and accordingly the enhanced activity. PMID:19874798

Chen, Baowei; Lei, Chenghong; Shin, Yongsoon; Liu, Jun

2009-10-27

253

Probing mechanisms for enzymatic activity enhancement of organophosphorus hydrolase in functionalized mesoporous silica  

PubMed Central

We have previously reported that organophosphorus hydrolase (OPH) can be spontaneously entrapped in functionalized mesoporous silica (FMS) with HOOC-as the functional groups and the entrapped OPH in HOOC-FMS showed enhanced enzyme specific activity. This work is to study the mechanisms that why OPH entrapped in FMS displayed the enhanced activity in views of OPH-FMS interactions using spectroscopic methods. The circular dichroism (CD) spectra show that, comparing to the secondary structure of OPH free in solution, OPH in HOOC-FMS displayed increased ?-helix/?-strand transition of OPH with increased OPH loading density. The fluorescence emission spectra of Trp residues were used to assess the tertiary structural changes of the enzyme. There was a 42% increase in fluorescence. This is in agreement with the fact that the fluorescence intensity of OPH was increased accompanying with the increased OPH activity when decreasing urea concentrations in solution. The steady-state anisotropy was increased after OPH entrapping in HOOC-FMS comparing to the free OPH in solution, indicating that protein mobility was reduced upon entrapment. The solvent accessibility of Trp residues of OPH was probed by using acrylamide as a collisional quencher. Trp residues of OPH-FMS had less solvent exposure comparing with free OPH in solution due to its electrostatical binding to HOOC-FMS thereby displaying the increased fluorescence intensity. These results suggest the interactions of OPH with HOOC-FMS resulted in the protein immobilization and a favorable conformational change for OPH in the crowded confinement space and accordingly the enhanced activity.

Chen, Baowei; Lei, Chenghong; Shin, Yongsoon; Liu, Jun

2009-01-01

254

Characterization of the micropore structure of activated carbons by adsorptions of nitrogen and some hydrocarbons  

SciTech Connect

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.

Guezel, F. [Dicle Univ., Diyarbakir (Turkey). Dept. of Chemistry

1999-02-01

255

Enhanced photocatalytic activity of bimodal mesoporous titania powders by C60 modification.  

PubMed

In this work, fullerene modified TiO(2) nanocomposites (denoted as C(60)/TiO(2)) with low C(60) loadings (0-1.5 wt.%) have been prepared by a simple hydrothermal method using tetrabutylorthotitanate (TBOT, Ti(OC(4)H(9))(4)) as the titanium precursor. The as-prepared C(60)/TiO(2) nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, UV-visible spectrophotometry, nitrogen adsorption, and X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy. The formation of hydroxyl radicals (?OH) on the surface of UV-illuminated TiO(2) is probed by photoluminescence using terephthalic acid as a probe molecule. Our results have demonstrated that C(60) molecules can be dispersed as a monolayer onto bimodal mesoporous TiO(2)via covalent bonding. The photocatalytic oxidation rate of gas-phase acetone over C(60)/TiO(2) nanocomposites is greater than that over pure TiO(2), commercial Degussa P25 (P25) and C(60)-TiO(2) counterparts prepared by simple impregnating mixing. In particular, 0.5 wt.% C(60)/TiO(2) nanocomposites show the greatest photocatalytic activity with the rate constant k exceeding that of P25 by a factor of 3.3. Based on the results of the current study, we propose that C(60) molecules doped onto TiO(2) act as "electron acceptors" responsible for the efficient separation of photogenerated charge carriers and the enhancement of photocatalytic activity. The proposed mechanism for the observed photocatalytic performance of C(60)/TiO(2) nanocomposites is further corroborated by experiments on hydroxyl radical and transient photocurrent response. PMID:21552575

Yu, Jiaguo; Ma, Tingting; Liu, Gang; Cheng, Bei

2011-05-06

256

Mesoporous materials and electrochemistry.  

PubMed

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

Walcarius, Alain

2013-01-18

257

Carbon Sequestration Monitoring Activities  

Microsoft Academic Search

In its 'Carbon Sequestration Technology Roadmap and Program Plan 2007' the U.S. Department of Energy (DOE)'s Office of Fossil Energy National Energy Technology Laboratory (NETL) identified as a major objective extended field tests to fully characterize potential carbon dioxide (CO) storage sites and to demonstrate the long-term storage of sequestered carbon (p. 5). Among the challenges in this area are

Carol Frost

2010-01-01

258

Pyrolytic Synthesis of Carbon Nanotubes from Sucrose on a Mesoporous Silicate  

Microsoft Academic Search

Multi?wall carbon nanotubes were synthesized from sucrose by a pyrolytic technique using mesopourous 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 multi?wall nanotubes showed them to be 15 nm in diameter, 200 nm in length and close?ended. There was variation in crystallinity

Emilie J. Siochi; Roy E. Crooks

2006-01-01

259

Shape Engineerable Single Walled Carbon Nanotube Solid as a Flexible Conducting Mesoporous Material  

Microsoft Academic Search

We present a new form of carbon nanotubes (CNT) material where CNTs are aligned and packed densely in a bulk solid. This single-walled carbon nanotube (SWNT) solid is fabricated from liquid-induced collapse of the sparse as-grown SWNT forest synthesized by super-growth CVD [1], which results in a 20x increase in mass density and a 70x increase in the Vickers hardness

Don N. Futaba; Kenji Hata; Tatsuki Hiraoka; Takeo Yamada; Kohei Mizuno; Yuhei Hayamizu; Tatsunori Namai; Yozo Kakudate; Osamu Tanaike; Hiroaki Hatori; Koji Miyake; Shinya Sasaki; Motoo Yumura; Sumio Iijima

2006-01-01

260

Removal of bromate ion using powdered activated carbon.  

PubMed

Bromate ion (BrO3-) removal from drinking water by powdered activated carbons (PACs) in bath mode was evaluated under various operational conditions. Six kinds of PACs, including wood-based carbon, fruit-based carbon, coal-based carbon, and these three carbons thermally deoxidized in a nitrogen atmosphere, were selected to investigate their capacity on BrO3- removal. With the highest zeta potential value and being richly mesoporous, coal-based carbon had a high and an excellent BrO3- adsorption efficiency. The removal content of BrO3- by per gram of coal-based carbon was 0.45 mg within 5 hr in 100 microg/L bromate solution. The surface characteristics of PACs and bromide formation revealed that both physical and chemical PACs properties simultaneously affected the adsorption-reduction process. Under acidic conditions, PACs possessed high zeta value and adequate basic groups and exhibited neutral or positive charges, promoting BrO3- adsorption-reduction on the carbon surface. Interestingly, the PACs thermally deoxidized in N2 atmosphere optimized their properties, e.g. increasing their zeta values and decreasing the oxygen content which accelerated the BrO3- removal rate. The maximum adsorption capacity of fruit-based carbon was the highest among all tested carbons (99.6 mg/g), possibly due to its highest pore volume. Remarkably, the thermal regeneration of PACs in N2 atmosphere could completely recover the adsorption capacity of PACs. The kinetic data obtained from carbons was analyzed using pseudo second-order and intraparticle diffusion models, with results showing that the intraparticle diffusion was the more applicable model to describe adsorption of BrO3- onto PACs. PMID:21462700

Wang, Lian; Zhang, Jie; Liu, Jingze; He, Hong; Yang, Min; Yu, Jianwei; Ma, Zichuan; Jiang, Feng

2010-01-01

261

Synthesis of Ordered Mesoporous Carbon Materials with Semi-Graphitized Walls via Direct In-situ Silica-Confined Thermal Decomposition of CH 4 and Their Hydrogen Storage Properties  

Microsoft Academic Search

Ordered mesoporous carbons with semi-graphitized walls (OMCs-SGW) were successfully obtained by in situ silica-confined thermal\\u000a decomposition of methane at low temperatures (800–1000 °C). This novel method, adopting ordered mesoporous silicas (OMSs)\\u000a as hard templates, impregnating OMSs with small amounts of group VIII metal (Fe, Co, Ni) nitrates as catalysts, combining\\u000a pore infiltration and carbonization\\/graphitization processes into a single step, provides an efficient

Zhangxiong Wu; Yunxia Yang; Dong Gu; Yunpu Zhai; Dan Feng; Qiang Li; Bo Tu; Paul A. Webley; Dong Yuan Zhao

2009-01-01

262

Catalytic activity of aryl alcohol oxidase immobilized in 3D-mesoporous silicates  

Microsoft Academic Search

Aryl alcohol oxidase was immobilized on two mesoporous materials, MS-A and MS-B. The immobilization rate for the larger pore material MS-A (11.5 nm) was higher than for the smaller pore material MS-B (4.2 nm). Furthermore, the sol–gel silica encapsulation of MS-immobilized enzymes improved thermal stability.

Katsuya Kato; Sindhu Seelan; Takao Saito

2009-01-01

263

Transition metal containing mesoporous silicas – redox properties, structure and catalytic activity  

Microsoft Academic Search

Mesoporous silicas of the MCM-41 type, containing iron, were prepared by synthesis and after framework synthesis, including deposition of iron from dried methanolic solution of iron(III) nitrate. Concentration of iron was up to 12 wt.%. In situ EXAFS, NO adsorption followed by IR spectroscopy and temperature programmed reduction suggest that the resulting iron in most cases is present mainly in

M. Stockenhuber; R. W. Joyner; J. M. Dixon; M. J. Hudson; G. Grubert

2001-01-01

264

Electroactive mesoporous tantalum oxide catalysts for nitrogen activation and ammonia synthesis.  

PubMed

A new mesoporous Ta oxide catalyst for conversion of dinitrogen to ammonia shows strong evidence for a novel mechanism involving low valent Ta on the surface, supporting recent work in organometallic chemistry using low valent early transition metals for dinitrogen cleavage. PMID:16767235

Yue, Chaoyang; Trudeau, Michel; Antonelli, David

2006-02-20

265

Mesoporous templated silicates: an overview of their synthesis, catalytic activation and evaluation of the stability  

Microsoft Academic Search

The most recent developments in the formation of new mesoporous templated zeolitic materials, characterized by surfaces of more than 1000 m2\\/g, are discussed in this paper. By adapting the synthesis parameters, such as type of silicium source, type of template, pH, temperature,… different materials can be synthesized with varying porosity and crystallinity. Besides the synthesis, much attention is focused on

T Linssen; K Cassiers; P Cool; E. F Vansant

2003-01-01

266

Effect of preparation conditions of carbon–silica adsorbents based on mesoporous silica gel Si100 and carbonised glucose on their pore structure  

Microsoft Academic Search

Two series of carbosils were prepared under dynamic (in an open rotary reactor) and static (in a high-pressure autoclave) conditions by pyrolysis of 0.01, 0.03, and 0.05mol of glucose\\/10g of mesoporous silica gel Si-100. Synthesised hybrid adsorbents contained from 5.2 to 21.4wt.% (first series) and 5.6–24.6wt.% (second series) of pyrocarbon, i.e. a high degree of glucose transformation into carbon matter

J Skubiszewska-Zieba; R. Leboda; O. Seledets; V. M. Gun’ko

2003-01-01

267

Mesoporous Nitrogen-Doped Carbon-Glass Ceramic Cathodes for Solid-State Lithium-Oxygen Batteries (Postprint).  

National Technical Information Service (NTIS)

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. ...

J. Kumar P. Kichambare S. Rodrigues

2012-01-01

268

Size-tunable Pt nanoparticles assembled on functionalized ordered mesoporous carbon for the simultaneous and on-line detection of glucose and L-lactate in brain microdialysate.  

PubMed

This study presents a facile electrochemical method for simultaneous and selective on-line detection of glucose and L-lactate in the striatum of anesthetic rats through the integration of selective electrochemical detection with in vivo microdialysis system. A positively-charged polyelectrolyte, (diallyldimethylammonium chloride) (PDDA), was attached onto carbon mesoporous material (CMM) through non-covalent interaction, which provided an ideal environment for the assembling and dispersion of nanoparticle electrocatalysts. Platinum nanoparticles with wide loadings from 5 to 50 wt% were successfully self-assembled on PDDA-functionalized CMM via electrostatic interaction. TEM results showed that with the increase in the Pt loadings, both the size and interconnectivity between particles increased, with particle sizes ranging from 3.2±0.4 to 6.8±1.4 nm. Moreover, the electrocatalytic activities of the as-prepared six Pt/PDDA-CMM hybrid nanocomposites were also observed to show an inverted-V-shaped profile as a function of loading amount of Pt NPs. Integrated with glucose oxidase (GOx), L-lactate oxidase (LOD) and the in vivo microdialysis system, the constructed dual oxidase/Pt/PDDA-CMM/Nafion biosensors were successfully applied for the simultaneous and on-line detection of glucose and L-lactate. After post-calibration, the basal level of glucose and L-lactate in the striatum of anesthetic rats was calculated to be 0.27±0.03 and 0.71±0.05 mM (mean ±s.d., n=3), respectively. What is more important, the dual oxidase biosensors almost suffered from little cross-talk, which is characteristic of an excellent sensor with high performance. This property, along with the good linearity and a high stability substantially enables this method promising application in physiology and pathology. PMID:23089326

Yu, Yanyan; Yang, Yan; Gu, Hui; Zhou, Tianshu; Shi, Guoyue

2012-10-05

269

Catalytic activation of carbon monoxide  

Microsoft Academic Search

Research into the catalytic activation of carbon monoxide has direct applications to the industrial use of synthesis gas as a feedstock for manufacturing synfuels and other organic chemicals. Synthesis gas is comprised of hydrogen\\/carbon monoxide mixtures produced from coal and other carbonaceous materials. Its potential uses include production of oxygenated organic material such as methanol and ethylene glycol, conversion to

Ford

1981-01-01

270

THERMAL REGENERATION OF ACTIVATED CARBON  

EPA Science Inventory

Ecologically, petrochemical wastes constitute a major hazard since waste materials contain relatively large amounts of non-biodegradable and toxic materials which may be discharged continuously. A three-part experimental study of activated carbon adsorption and thermal regenerati...

271

MnO Nanoparticle@Mesoporous Carbon Composites Grown on Conducting Substrates Featuring High-performance Lithium-ion Battery, Supercapacitor and Sensor  

PubMed Central

We demonstrate a facile, two-step coating/calcination approach to grow a uniform MnO nanoparticle@mesoporous carbon (MnO@C) composite on conducting substrates, by direct coating of the Mn-oleate precursor solution without any conducting/binding reagents, and subsequent thermal calcination. The monodispersed, sub-10?nm MnO nanoparticles offer high theoretical energy storage capacities and catalytic properties, and the mesoporous carbon coating allows for enhanced electrolyte transport and charge transfer towards/from MnO surface. In addition, the direct growth and attachment of the MnO@C nanocomposite in the supporting conductive substrates provide much reduced contact resistances and efficient charge transfer. These excellent features allow the use of MnO@C nanocomposites as lithium-ion battery and supercapacitor electrodes for energy storage, with high reversible capacity at large current densities, as well as excellent cycling and mechanical stabilities. Moreover, this MnO@C nanocomposite has also demonstrated a high sensitivity for H2O2 detection, and also exhibited attractive potential for the tumor cell analysis.

Wang, Tianyu; Peng, Zheng; Wang, Yuhang; Tang, Jing; Zheng, Gengfeng

2013-01-01

272

MnO Nanoparticle@Mesoporous Carbon Composites Grown on Conducting Substrates Featuring High-performance Lithium-ion Battery, Supercapacitor and Sensor.  

PubMed

We demonstrate a facile, two-step coating/calcination approach to grow a uniform MnO nanoparticle@mesoporous carbon (MnO@C) composite on conducting substrates, by direct coating of the Mn-oleate precursor solution without any conducting/binding reagents, and subsequent thermal calcination. The monodispersed, sub-10?nm MnO nanoparticles offer high theoretical energy storage capacities and catalytic properties, and the mesoporous carbon coating allows for enhanced electrolyte transport and charge transfer towards/from MnO surface. In addition, the direct growth and attachment of the MnO@C nanocomposite in the supporting conductive substrates provide much reduced contact resistances and efficient charge transfer. These excellent features allow the use of MnO@C nanocomposites as lithium-ion battery and supercapacitor electrodes for energy storage, with high reversible capacity at large current densities, as well as excellent cycling and mechanical stabilities. Moreover, this MnO@C nanocomposite has also demonstrated a high sensitivity for H2O2 detection, and also exhibited attractive potential for the tumor cell analysis. PMID:24045767

Wang, Tianyu; Peng, Zheng; Wang, Yuhang; Tang, Jing; Zheng, Gengfeng

2013-09-18

273

Enhanced catalytic activity for butane isomerization with alumina-promoted tungstated mesoporous zirconia  

Microsoft Academic Search

Mesoporous zirconia, synthesized from surfactant templating, was used to disperse alumina and tungstate as a catalyst (denoted as AW\\/m-ZrO2) for the isomerization of n-butane. At a relatively low temperature of calcination (700°C), the catalyst (AW\\/m-700) performed exceptionally well, both in maximum rate and stability, at a temperature of 250°C. This was lower than the temperature needed by other tungstated zirconia-based

Chi-Chau Hwang; Xiao-Rong Chen; She-Tin Wong; Chang-Lin Chen; Chung-Yuan Mou

2007-01-01

274

Structural, Photocatalytic Activity and Photovoltaic Properties of Mesoporous Anatase Titania Nanopowders Prepared by Hydrothermal Method  

Microsoft Academic Search

Mesoporous anatase TiO2 nanopowder was synthesized by hydrothermal method at 130 o C for 12 h. The samples characterized by XRD, SEM, TEM, SAED, HRTEM, and BET surface area. The as-synthesized sample with narrow pore size distribution had average pore diameter about 3-4 nm. The specific BET surface area of the as-synthesized sample was about 193 m 2 \\/g, higher

Sorapong Pavasupree; Jaturong Jitputti; Supachai Ngamsinlapasathian; Yoshikazu Suzuki; Susumu Yoshikawa

275

The influence of metal loading and activation on mesoporous materials supported nickel phosphide hydrotreating catalysts  

Microsoft Academic Search

Ordered mesoporous materials (SBA-15 and KIT-6 silica and MFI zeolite) supported nickel phosphide (NixPy) hydrotreating catalysts were prepared by reduction of oxidic precursors with an initial stoichiometric Ni\\/P ratio of 2 The metal loading (20 and 30wt.% NixPy) and pretreatment conditions (773K or 873K reduction temperature, in situ sulfidation at 723K) of the precursors were varied. Temperature programmed reduction, in

Tamás I. Korányi; Alessandro E. Coumans; Emiel J. M. Hensen; Ryong Ryoo; Hei Seung Kim; Éva Pfeifer; Zsolt Kasztovszky

2009-01-01

276

Carbon Sequestration Monitoring Activities  

SciTech Connect

In its 'Carbon Sequestration Technology Roadmap and Program Plan 2007' the U.S. Department of Energy (DOE)'s Office of Fossil Energy National Energy Technology Laboratory (NETL) identified as a major objective extended field tests to fully characterize potential carbon dioxide (CO{sub 2}) storage sites and to demonstrate the long-term storage of sequestered carbon (p. 5). Among the challenges in this area are 'improved understanding of CO{sub 2} flow and trapping within the reservoir and the development and deployment of technologies such as simulation models and monitoring systems' (p. 20). The University of Wyoming (UW), following consultations with the NETL, the Wyoming State Geological Survey, and the Governor's office, identified potential for geologic sequestration of impure carbon dioxide (CO{sub 2}) in deep reservoirs of the Moxa Arch. The Moxa Arch is a 120-mile long north-south trending anticline plunging beneath the Wyoming Thrust Belt on the north and bounded on the south by the Uinta Mountains. Several oil and gas fields along the Moxa Arch contain accumulations of natural CO{sub 2}. The largest of these is the La Barge Platform, which encompasses approximately 800 square miles. Several formations may be suitable for storage of impure CO{sub 2} gas, foremost among them the Madison Limestone, Bighorn Dolomite, and Nugget Sandstone. This project responded to the challenges described above by preparing a geological site characterization study on the Moxa Arch. The project included four priority research areas: (A) geological characterization of geologic structure of the Arch, the fault, and fracture patterns of the target formations and caprocks, (B) experimental characterization of carbon dioxide-brine-rock reactions that may occur, (C) optimization of geophysical and numerical models necessary for measurement, monitoring and verification (MMV), and (D) a preliminary performance assessment. Research work to accomplish these goals was coordinated by one administrative task under the direction of Dr. Carol Frost, Professor of Geology and Geophysics (Task 1.0), and one task devoted to designing and creating an interdisciplinary, project-specific carbon cyberinfrastructure to support collaborative carbon dioxide sequestration research among University of Wyoming scientists and their collaborators, performed by Jeff Hammerlinck, Director of the Wyoming Geographic Information Science Center at the University of Wyoming (Task 1.5). The results of these tasks are presented in the Introduction and in Chapter 1, respectively.

Carol Frost

2010-11-30

277

[Adsorption and desorption of dyes by waste-polymer-derived activated carbons].  

PubMed

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

Lian, Fei; Liu, Chang; Li, Guo-Guang; Liu, Yi-Fu; Li, Yong; Zhu, Ling-Yan

2012-01-01

278

Synthesis and photocatalytic activity of titania monoliths prepared with controlled macro- and mesopore structure.  

PubMed

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

Drisko, Glenna L; Zelcer, Andrés; Wang, Xingdong; Caruso, Rachel A; Soler-Illia, Galo J de A A

2012-07-23

279

Hierarchically Structured Sulfur\\/Carbon Nanocomposite Material for High Energy Lithium Battery  

Microsoft Academic Search

We report herein a hierarchically structured sulfur-carbon (S\\/C) nanocomposite material as the high surface-area cathode for rechargeable lithium batteries. A porous carbon with a uniform distribution of mesopores of 7.3 nm has been synthesized through a soft-template synthesis method. The potassium hydroxide activation of this mesoporous carbon results in a bimodal porous carbon with added microporosity of less than 2

Chengdu Liang; Nancy J. Dudney; Jane Y. Howe

2009-01-01

280

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

NASA Astrophysics Data System (ADS)

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.

Vargas, M.; Rincón, M. E.; Sánchez, M.; Hernández, G.; Ramos, E.

2008-02-01

281

Characteristics of activated carbon prepared from pistachio-nut shell by zinc chloride activation under nitrogen and vacuum conditions.  

PubMed

Activated carbons with well-developed pore structures were prepared from pistachio-nut shells by chemical activation using zinc chloride under both nitrogen atmosphere and vacuum conditions. The effects of preparation parameters on the carbon pore structure were studied in order to optimize these parameters. It was found that under vacuum conditions, the characteristics of the activated carbons produced are better than those under nitrogen atmosphere. The impregnation ratio, the activation temperature, and the activation hold time are the important parameters that influence the characteristics of the activated carbons. The optimum experimental conditions for preparing predominantly microporous activated carbons with high pore surface area and micropore volume are an impregnation ratio of 0.75, an activation temperature of 400 degrees C, and a hold time of 1 h. Under these conditions, the BET surface areas of the carbons activated under nitrogen atmosphere and vacuum conditions were 1635.37 and 1647.16 m2/g, respectively. However, at a ZnCl2 impregnation ratio of 1.5, a furnace temperature of 500 degrees C, and a hold time of 2 h, the predominantly mesoporous activated carbon prepared under vacuum condition had a BET surface area of 2527 m2/g. Fourier transform infrared spectra were used to detect changes in the surface functional groups of the samples during the different preparation stages. PMID:16002081

Lua, Aik Chong; Yang, Ting

2005-10-15

282

Activity enhancement of mesoporous silicate FSM-16 by metal ion-exchange and sulfiding with hydrogen sulfide for acid-catalyzed reactions  

Microsoft Academic Search

The modification of mesoporous silicate FSM-16 by metal ion-exchange and sulfiding with hydrogen sulfide was studied through the isomerization of 1-butène, cis-2-butene and cyclopropane. It was revealed that the catalytic activities of MeFSM-16 were remarkably enhanced by sulfiding with hydrogen sulfide due to the formation of new Brönsted acid sites

M. Sugioka; L Andalaluna; J. K. A. Dapaah

2000-01-01

283

Templated nanoscale porous carbons  

Microsoft Academic Search

This manuscript reviews key developments in the important and rapidly expanding area of templated porous carbons. The porosity covered ranges from microporous to mesoporous and macroporous carbons. Two modes of templating, using so-called hard and soft templates, are covered. In particular, for hard templating, zeolite templating generates microporous carbons, mesoporous silicates yield mesoporous carbons, while colloidal particles are replicated to

Yongde Xia; Zhuxian Yang; Robert Mokaya

2010-01-01

284

Adsorption of C6 hydrocarbon rings on mesoporous catalyst supports  

NASA Astrophysics Data System (ADS)

The adsorption of cyclohexane, cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene and benzene was studied on pristine and shortened multi-wall carbon nanotubes, SBA-15 and a novel high surface area mesoporous carbon (CMH). Data were fitted with the Freundlich adsorption equation and the correlation between the fitted parameters and quantitative structure-activity relationships (QSAR) descriptors of the adsorbates was analyzed. Adsorption on carbon nanotubes is more sensitive to the partial pressure of unsaturated adsorbates, whereas SBA-15 is more sensitive to saturated partners. CMH is a neutral material that appears to be particularly useful for studying catalyst particle efficiency without the influence of the support itself.

Rémiás, Róbert; Sápi, András; Puskás, Róbert; Kukovecz, Ákos; Kónya, Zoltán; Kiricsi, Imre

2009-11-01

285

Grand canonical Monte Carlo simulation of methane–carbon dioxide mixtures on ordered mesoporous carbon CMK-1  

Microsoft Academic Search

Grand canonical Monte Carlo (GCMC) simulations were carried out to investigate the adsorption of CH4 and CO2 mixture on an ordered carbon material CMK-1. In the simulation, the fluid molecules are both modeled as Lennard–Jones spheres, and the CMK-1 adsorbent is characterized by the rod-aligned slitlike (RSP) pore model to emphasize its textural and grooved structure. The effects of temperature,

Xuan Peng; Dapeng Cao; Jinsong Zhao

2009-01-01

286

Equilibrium and kinetics analysis of carbon dioxide capture using immobilized amine on a mesoporous silica  

SciTech Connect

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.

Monazam, E., Shadle, L., Pennline, H., Miller, D., Fauth, D., Hoffman, J., Gray, M.

2012-01-01

287

Dye adsorption onto activated carbons from tyre rubber waste using surface coverage analysis.  

PubMed

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

Mui, Edward L K; Cheung, W H; Valix, Marjorie; McKay, Gordon

2010-04-02

288

Activated carbon to the rescue  

SciTech Connect

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.

Sen, S. [Calgon Carbon Corp., Pittsburgh, PA (United States)

1996-03-01

289

Nanocrystalline intermetallics on mesoporous carbon for direct formic acid fuel cell anodes  

Microsoft Academic Search

Shape- and size-controlled supported metal and intermetallic nanocrystallites are of increasing interest because of their catalytic and electrocatalytic properties. In particular, intermetallics PtX (X = Bi, Pb, Pd, Ru) are very attractive because of their high activity as fuel-cell anode catalysts for formic acid or methanol oxidation. These are normally synthesized using high-temperature techniques, but rigorous size control is very

Xiulei Ji; Kyu Tae Lee; Reanne Holden; Lei Zhang; Jiujun Zhang; Gianluigi A. Botton; Martin Couillard; Linda F. Nazar

2010-01-01

290

Adsorption of phenol and reactive dye from aqueous solution on activated carbons derived from solid wastes.  

PubMed

Activated carbons were produced from several solid wastes, namely, waste PET, waste tires, refuse derived fuel and wastes generated during lactic acid fermentation from garbage. Activated carbons having various pore size distributions were obtained by the conventional steam-activation method and via the pre-treatment method (i.e., mixture of raw materials with a metal salt, carbonization and acid treatment prior to steam-activation) that was proposed by the authors. The liquid-phase adsorption characteristics of organic compounds from aqueous solution on the activated carbons were determined to confirm the applicability of these carbons, where phenol and a reactive dye, Black5, were employed as representative adsorbates. The hydrophobic surface of the carbons prepared was also confirmed by water vapor adsorption. The characteristics of a typical commercial activated carbon were also measured and compared. It was found that the activated carbons with plentiful mesopores prepared from PET and waste tires had quite high adsorption capacity for large molecules. Therefore they are useful for wastewater treatment, especially, for removal of bulky adsorbates. PMID:15026233

Nakagawa, Kyuya; Namba, Akio; Mukai, Shin R; Tamon, Hajime; Ariyadejwanich, Pisit; Tanthapanichakoon, Wiwut

2004-04-01

291

One-step synthesis of N- and F-codoped mesoporous TiO2 photocatalysts with high visible light activity.  

PubMed

We report on a novel approach to the synthesis of N- and F-codoped mesoporous TiO2 photocatalysts via a reproducible, rapid and single-step combustion method. TiF4 was used as the precursor to provide the source of Ti and F, while urea was used as the fuel as well as the source of the N dopant. The as-synthesized samples were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy. The specific surface areas of the samples were determined using a Quantachrome Nova 2200 for the N2 adsorption/desorption under liquid-nitrogen temperature. Our studies show that the fabricated N- and F-codoped TiO2 photocatalysts have mesoporous structure and a very large specific surface area (155.3 m(2) g(-1)) and that the codoping of N and F significantly narrows the TiO2 bandgap energy from 3.2 to 2.45 eV. We further studied the photocatalytic activity of the synthesized N- and F-codoped mesoporous TiO2 through the decomposition of acetic acid, showing that the N- and F-codoped mesoporous TiO2 catalyst fabricated in this study exhibits superb photocatalytic activity and visible light response compared to one of the best commercially available TiO2 photocatalysts, P25. PMID:20097984

Wu, Guosheng; Wen, Jiali; Nigro, Samantha; Chen, Aicheng

2010-01-25

292

Preparation of activated carbons from raw and biotreated agricultural residues for removal of volatile organic compounds.  

PubMed

Activated carbons with diverse physical and chemical properties were produced from four agriculture residues, including raw barley husk, biotreated barley husk, rice husk, and pistachio shell. Results showed that with adequate steam activation (30-90 min, 50% H2O(g),/50% N2), activated carbons with surface areas between 360 and 950 m2 g(-1) were developed. Further increases in the activation time destroyed the pore structure of activated carbons, which resulted in a decrease in the surface area and pore volume. Biotreated agricultural residues were found to be suitable precursors for producing mesoporous activated carbons. The oxygen content of activated carbons increased with increasing activation time. Results from X-ray photoelectron spectroscopy examination further suggested that H2O molecules react with the carbon surface, enhancing the deconvoluted peak area of carbonyl and carboxyl groups. Equilibrium adsorption of toluene indicated that the adsorption capacities increased with an increase in the inlet toluene concentration and a decrease in temperature. The adsorption isotherms were successfully fitted with Freundlich, Langmuir, and Dubinin-Radushkevich equations. Activated carbons derived from agricultural residues appear to be more applicable to adsorb volatile organic compounds at a low concentration and high-temperature environment. PMID:21608494

Hsi, Hsing-Cheng; Horng, Richard S; Pan, Tai-An; Lee, Shin-Ku

2011-05-01

293

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

NASA Astrophysics Data System (ADS)

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.

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

2005-08-01

294

Amine-modified SBA12 mesoporous silica for carbon dioxide capture: Effect of amine basicity on sorption properties  

Microsoft Academic Search

SBA-12 mesoporous silica was modified by 3-aminopropyl (AP), 3-(methylamino)propyl (MAP) and 3-(phenylamino)propyl (PAP) ligands. The electronic effects in AP, MAP and PAP ligands resulted in different surface basicity of the modified silica materials. The materials were characterized by thermogravimetry, X-ray powder diffraction, nitrogen adsorption\\/desorption and transmission electron microscopy. The CO2 sorption\\/desorption experiments performed at 25oC by gravimetric method showed that

V. Zelenak; D. Halamova; L. Gaberova; E. Bloch; P. Llewellyn

2008-01-01

295

Enzyme immobilisation using siliceous mesoporous molecular sieves  

Microsoft Academic Search

The use of mesoporous molecular sieves in enzyme immobilisation has been studied. Three different types of mesoporous sieves (MCM-41, MCM-48 and SBA-15) were selected because of the differences in their pore dimensions and structures. Commercially available porous silica gel was chosen for comparison. The model enzyme chosen in this study was trypsin. The samples of immobilised trypsin were active for

Humphrey H. P. Yiu; Paul A. Wright; Nigel P. Botting

2001-01-01

296

Catalytic activity of active carbons impregnated before activation of pinewood sawdust and nutshells to be used on the control of atmospheric emissions.  

PubMed

This work analyses the catalytic activity of metal oxides impregnated on activated carbons to be used for the complete oxidation of benzene present in atmospheric emissions. When the impregnation step is performed before CO2 activation, the knowledge about catalytic activity is as yet quite scarce, being the main objective of the study here reported. Pinewood sawdust and nutshells were recycled to produce the activated carbons. Non-expensive metal oxides (CoO, Co3O4 and CrO3) were impregnated. When the impregnation was performed before CO2 activation instead of after activation, at 523 K the kinetic constants were 3.6-4.3 times higher for sawdust carbons, and 2.1-2.7 times higher for nutshell carbons, due to a better metal oxide dispersion on higher mesopore areas and on wider micropores. With Co3O4 as catalyst, a benzene conversion of 90% was reached at a lower temperature than with CrO3 (472 and 558 K, respectively). The carbons impregnated before CO2 activation allowed very good conversions at temperatures that guarantee carbon stability (lower than 575 K). The results obtained led to the conclusion that activated carbon is a suitable support for metal oxide catalyst aiming the complete oxidation of benzene, mainly if an adequately porous texture is induced, proceeding to the impregnation before CO2 activation. PMID:15752858

Alvim-Ferraz, Maria da Conceição M; Gaspar, Carla Maria T B

2005-03-17

297

Molecular sieve properties of mesoporous silica with intraporous nanocarbon.  

PubMed

Biporous carbon-silica materials (CSM) with molecular sieve properties and high sorption capacity were developed by synthesizing nano-sized carbon crystallites in the mesopores of Al-MCM-41. PMID:20107653

de Clippel, F; Harkiolakis, A; Ke, X; Vosch, T; Van Tendeloo, G; Baron, G V; Jacobs, P A; Denayer, J F M; Sels, B F

2009-12-07

298

Mesoporous and biocompatible surface active silica aerogel synthesis using choline formate ionic liquid.  

PubMed

In this paper, we report the preparation and characterization of mesoporous and biocompatible transparent silica aerogel by the sol-gel polymerization of tetraethyl orthosilicate using ionic liquid. Choline cation based ionic liquid allows the silica framework to form in a non collapsing environment and controls the pore size of the gel. FT-IR spectra reveal the interaction of ionic liquid with surface -OH of the gel. DSC thermogram giving the evidence of confinement of ionic liquid within the silica matrix, which helps to avoid the shrinkage of the gel during the aging process. Nitrogen sorption measurements of gel prepared with ionic liquid exhibit a low surface area of 100.53 m2/g and high average pore size of 3.74 nm. MTT assay proves the biocompatibility and cell viability of the prepared gels. This new nanoporous silica material can be applied to immobilize biological molecules, which may retain their stability over a longer period. PMID:21565470

Meera, Kamal Mohamed Seeni; Sankar, Rajavelu Murali; Jaisankar, Sellamuthu N; Mandal, Asit Baran

2011-04-15

299

Redox active mesoporous hybrid materials by in situ syntheses with urea-linked triethoxysilylated phenothiazines.  

PubMed

Triethoxysilyl functionalized phenothiazinyl ureas were synthesized and immobilized by in situ synthesis into mesoporous hybrid materials. The designed precursor molecules influence the structure of the final materials and the intermolecular distance of the phenothiazines. XRD and N(2) adsorption measurements indicate the presence of highly ordered two-dimensional hexagonally structured functional materials, while the incorporation of the organic compounds in the solid materials was proved by means of (13)C and (29)Si solid state NMR spectroscopy as well as by FT-IR spectroscopy. Upon oxidation with (NO)BF(4) or SbCl(5), stable phenothiazine radical cations were generated in the pores of the materials, which was detected by means of UV/Vis, emission, and EPR spectroscopies. PMID:20681016

Zhou, Zhou; Franz, Adam W; Bay, Sarah; Sarkar, Biprajit; Seifert, Andreas; Yang, Piaoping; Wagener, Alex; Ernst, Stefan; Pagels, Markus; Müller, Thomas J J; Thiel, Werner R

2010-09-01

300

Production of activated carbons from Illinois coals  

SciTech Connect

Although the predominant use of coal is for combustion applications, more beneficial, reasonable and profitable uses may be as a resource for the production of chemicals, and materials, including activated carbon. Activated carbons represent a family of carbonaceous substances manufactured by processes that develop the carbon`s adsorptive properties. The primary objective of this study was to demonstrate that an activated carbon with good surface area and chemical properties could be produced from an Illinois coal.

Hippo, E.J.; O`Brien, W.S. [Southern Illinois Univ., Carbondale, IL (United States); Sun, Jian [Univ. of Illinois, Champaign, IL (United States)

1996-12-31

301

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

PubMed

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

Kichambare, Padmakar; Rodrigues, Stanley; Kumar, Jitendra

2011-12-14

302

Photoconductivity of activated carbon fibers  

SciTech Connect

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.

Kuriyama, K.; Dresselhaus, M.S. (Massachusetts Inst. of Tech., Cambridge, MA (USA))

1990-08-01

303

Adsorption over polyacrylonitrile based carbon monoliths  

NASA Astrophysics Data System (ADS)

Highly porous activated carbon monoliths have been prepared from mesoporous polyacrylonitrile (PAN) monolith as the carbon precursor. The mesoporous PAN monoliths are fabricated by a unique and facile template-free method which on carbonization gives N-doped activated carbon monoliths. The carbonization is achieved via two step thermal process which includes pretreatment in air leading to cyclization and subsequent aromatization of the PAN moieties followed by carbonization in a mixture of argon and carbon dioxide to give a layered carbon framework. Nitrogen sorption experiments carried over these carbon monoliths revealed high surface area (ca. 2500 m2g-1) for these materials with precise micropore size distribution. The activated carbons show extraordinarily high CO2 capture capacity and the uptake up to 3 bar has been found to be as high as 22.5 and 10.6 mmol/g at 273 K and 298 K, respectively.

Nandi, Mahasweta; Dutta, Arghya; Patra, Astam Kumar; Bhaumik, Asim; Uyama, Hiroshi

2013-02-01

304

Sol-gel thin-film based mesoporous silica and carbon nanotubes for the determination of dopamine, uric acid and paracetamol in urine.  

PubMed

This work describes the preparation, characterization and application of a hybrid material composed of disordered mesoporous silica (SiO2) modified with multiwalled carbon nanotubes (MWCNTs), obtained by the sol-gel process using HF as the catalyst. This hybrid material was characterized by N2 adsorption-desorption isotherms, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission microscopy (HR-TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). This new hybrid material was used for the construction of a thin film on a glassy carbon electrode. The modified electrode using this material was designated SiO2/MWCNT/GCE. The electrocatalytic properties of the electrode toward dopamine, uric acid and paracetamol oxidation were studied by differential pulse voltammetry. Well-defined and separated oxidation peaks were observed in phosphate buffer solution at pH 7.0, in contrast with the ill-defined peaks observed with unmodified glassy carbon electrodes. The electrode had high sensitivity for the determination of dopamine, uric acid and paracetamol, with the limits of detection obtained using statistical methods, at 0.014, 0.068 and 0.098µmolL(-1), respectively. The electrode presented some important advantages, including enhanced physical rigidity, surface renewability by polishing and high sensitivity, allowing the simultaneous determination of these three analytes in a human urine sample. PMID:24148467

Canevari, Thiago C; Raymundo-Pereira, Paulo A; Landers, Richard; Benvenutti, Edilson V; Machado, Sérgio A S

2013-07-31

305

Solvent-regenerated activated carbon  

SciTech Connect

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.

McLaughlin, H. (Fluids Design Corp., Troy, NY (USA))

1988-07-01

306

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

SciTech Connect

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.

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

2006-01-26

307

Transesterification of vegetable oils on basic large mesoporous alumina supported alkaline fluorides—Evidences of the nature of the active site and catalytic performances  

Microsoft Academic Search

KF, LiF and CsF\\/Al2O3 catalysts with different loadings from 1 to 20 wt% were prepared using aqueous solutions of the alkaline fluoride compounds by wet impregnation of basic mesoporous MSU-type alumina. The catalysts were activated under Ar at 400?°C for 2 h and monitored by in situ XRD measurements. The catalysts were also characterized using several techniques: N2 adsorption\\/desorption isotherms

Marian Verziu; Mihaela Florea; Simion Simon; Viorica Simon; Petru Filip; Vasile I. Parvulescu; Christopher Hardacre

2009-01-01

308

Activated carbon fibers with a high heteroatom content by chemical activation of PBO with phosphoric acid.  

PubMed

The preparation of activated carbon fibers (ACFs) by phosphoric acid activation of poly(p-phenylene benzobisoxazole) (PBO) fibers was studied, with particular attention to the effects of impregnation ratio and carbonization temperature on porous texture. Phosphoric acid has a strong effect on PBO degradation, lowering the temperature range at which the decomposition takes place and changing the number of mass loss steps. Chemical analysis results indicated that activation with phosphoric acid increases the concentration of oxygenated surface groups; the resulting materials also exhibiting high nitrogen content. ACFs are obtained with extremely high yields; they have well-developed porosity restricted to the micropore and narrow mesopore range and with a significant concentration of phosphorus incorporated homogeneously in the form of functional groups. An increase in the impregnation ratio leads to increases in both pore volume and pore size, maximum values of surface area (1250 m(2)/g) and total pore volume (0.67 cm(3)/g) being attained at the highest impregnation ratio (210 wt % H(3)PO(4)) and lowest activation temperature (650 °C) used; the corresponding yield was as large as 83 wt %. The obtained surface areas and pore volumes were higher than those achieved in previous works by physical activation with CO(2) of PBO chars. PMID:22401268

Vázquez-Santos, M B; Suárez-García, F; Martínez-Alonso, A; Tascón, J M D

2012-03-26

309

Effect of surface phosphorus functionalities of activated carbons containing oxygen and nitrogen on electrochemical capacitance  

PubMed Central

Micro/mesoporous activated carbons containing oxygen and phosphorus heteroatoms were modified by incorporation of nitrogen using melamine and urea precursors. The surface chemistry was analyzed by the means of elemental analysis, XPS, and 31P MAS NMR. The results indicate that upon the incorporation of nitrogen at high temperatures not only new species involving carbon/nitrogen/oxygen are formed but also the phosphorous environment is significantly altered. Both urea and melamine precursors have similar effects on formation of P–N and P–C bonds. These compounds, although present in small but measurable quantities seem to affect the performance of carbons in electrochemical capacitors. With an increase in the heterogeneity of phosphorus containing species and with a decrease in the content pyrophosphates the capacitance increases and the retention ratio of the capacitor is improved.

Hulicova-Jurcakova, Denisa; Seredych, Mykola; Lu, Gao Qing; Kodiweera, N.K.A.C.; Stallworth, Phillip E.; Greenbaum, Steven; Bandosz, Teresa J.

2009-01-01

310

Studies and characterisations of various activated carbons used for carbon\\/carbon supercapacitors  

Microsoft Academic Search

Various activated carbons from the PICA Company have been tested in supercapacitor cells in order to compare their performances. The differences measured in terms of specific capacitance and cell resistance are presented. Porosity measurements made on activated carbon powders and electrode allowed a better understanding of the electrochemical behaviour of these activated carbons. In this way, the PICACTIF SC carbon

J Gamby; P. L Taberna; P Simon; J. F Fauvarque; M Chesneau

2001-01-01

311

Bimetallic catalysis on carbon nanotubes for the selective hydrogenation of cinnamaldehyde  

Microsoft Academic Search

Carbon nanotube-based catalysts (Pt, Ru, and Pt–Ru) were developed and compared with their analogues on activated carbon for the selective reduction of cinnamaldehyde to the corresponding unsaturated alcohol. The use of a mesoporous nanostructured support, which makes mass transfer limitations less significant, gave far better activities than microporous activated carbon. A bimetallic system was found to afford a remarkably high

Hung Vu; Filomena Gonçalves; Régis Philippe; Emmanuel Lamouroux; Massimiliano Corrias; Yolande Kihn; Dominique Plee; Philippe Kalck; Philippe Serp

2006-01-01

312

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)

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), N2 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.

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

2011-02-01

313

An ordered mesoporous aluminosilicate with completely crystalline zeolite wall structure.  

PubMed

An ordered mesoporous aluminosilicate with completely crystalline zeolite pore wall structure, denoted as OMZ-1, was successfully synthesized by recrystallization of SBA-15 using in situ formed CMK-5 as the hard template. The role of carbon material not only serves as a hard template to preserve ordered mesoporous structure but also kinetically controls the crystallization process to form large crystals. PMID:16910631

Fang, Yunming; Hu, Haoquan

2006-08-23

314

Multiwalled carbon nanotubes drive the activity of metal@oxide core-shell catalysts in modular nanocomposites.  

PubMed

Rational nanostructure manipulation has been used to prepare nanocomposites in which multiwalled carbon nanotubes (MWCNTs) were embedded inside mesoporous layers of oxides (TiO(2), ZrO(2), or CeO(2)), which in turn contained dispersed metal nanoparticles (Pd or Pt). We show that the MWCNTs induce the crystallization of the oxide layer at room temperature and that the mesoporous oxide shell allows the particles to be accessible for catalytic reactions. In contrast to samples prepared in the absence of MWCNTs, both the activity and the stability of core-shell catalysts is largely enhanced, resulting in nanocomposites with remarkable performance for the water-gas-shift reaction, photocatalytic reforming of methanol, and Suzuki coupling. The modular approach shown here demonstrates that high-performance catalytic materials can be obtained through the precise organization of nanoscale building blocks. PMID:22716042

Cargnello, Matteo; Grzelczak, Marek; Rodríguez-González, Benito; Syrgiannis, Zois; Bakhmutsky, Kevin; La Parola, Valeria; Liz-Marzán, Luis M; Gorte, Raymond J; Prato, Maurizio; Fornasiero, Paolo

2012-07-10

315

Enhanced photocatalytic activity of mesoporous S-N-codoped TiO2 loaded with Ag nanoparticles  

NASA Astrophysics Data System (ADS)

Mesoporous S-N-codoped TiO2 photocatalyst loaded with Ag nanoparticles (NPs) were synthesized via a facile photochemical deposition approach. The samples were characterized by using x-ray photoelectron spectroscopy, transmission electron microscope, energy-dispersive x-ray spectroscopy (EDS) and UV-visible spectra. TEM images showed that metallic Ag NPs were deposited on S-N-codoped TiO2 NPs, which was further confirmed by EDS and surface plasmon absorption shown in UV-visible spectra. The samples possessed a homogeneous pore diameter and a high surface area of 153.3 m2 g-1 for the Ag-loaded S-N-codoped TiO2-vis samples, which facilitated the great enhancement of adsorption capacity for dye methyl orange (MO) molecules. Compared with S-N-codoped TiO2, Ag-loaded photocatalysts exhibited significantly enhanced catalytic activity under visible irradiation (? >= 420 nm), which was more than 14 times higher photocatalytic activity for MO degradation than that of P25 TiO2 under the same condition.

Xie, Yi; Kum, Jongmin; Zhao, Xiujian; Cho, Sung Oh

2011-08-01

316

Excellent photocatalytic degradation activities of ordered mesoporous anatase TiO2-SiO2 nanocomposites to various organic contaminants.  

PubMed

Ordered 2-D hexagonal mesoporous TiO(2)-SiO(2) nanocomposites consisted of anatase TiO(2) nanocrystals and amorphous SiO(2) nanoparticles, with large mesochannels and high specific surface areas, have been extensively and detailedly evaluated using various cationic dyes (methylene blue, safranin O, crystal violet, brilliant green, basic fuchsin and rhodamine-6G), anionic dyes (acid fuchsin, orange II, reactive brilliant red X3B and acid red 1) and microcystin-LR. We use mesoporous 80TiO(2)-20SiO(2)-900 for the degradation of cationic dyes and MC-LR, due to the dominant adsorption of SiOH groups and synergistic role of coupled adsorption and photocatalytic oxidation. For anionic dyes, due to the adsorption results predominantly from TiOH groups, our strategy realizes the enhanced photocatalytic oxidation by strong surface acids and larger available specific surface area. Based on this, we prepared 90TiO(2)-10SiO(2)-700 to degrade them. The results show that our samples exhibit excellent degradation activities to all the contaminants, which are much higher than that of P25 photocatalyst. The dyes are not only decolorized promptly but degraded readily as well. It is strongly indicated that our mesoporous nanocomposites are considerably stable and reusable. These results demonstrate that our mesoporous TiO(2)-SiO(2) nanocomposites present extensive and promising application in the fast and highly efficient degradation of various organic pollutants. PMID:22749122

Dong, Weiyang; Sun, Yaojun; Ma, Qingwei; Zhu, Li; Hua, Weiming; Lu, Xinchun; Zhuang, Guoshun; Zhang, Shicheng; Guo, Zhigang; Zhao, Dongyuan

2012-06-12

317

Synthesis and photocatalytic activity of co-doped mesoporous TiO{sub 2} on Brij98/CTAB composite surfactant template  

SciTech Connect

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.

Zhang Xiaotong [School of Chemical Engineering, Shandong Institute of Light Industry, and Key Laboratory for Fine Chemicals of Shandong Province, Jinan, 250353 Shandong (China); Zhou Guowei, E-mail: guoweizhou@hotmail.co [School of Chemical Engineering, Shandong Institute of Light Industry, and Key Laboratory for Fine Chemicals of Shandong Province, Jinan, 250353 Shandong (China); Xu Jing; Bai Guangwei; Wang Lei [School of Chemical Engineering, Shandong Institute of Light Industry, and Key Laboratory for Fine Chemicals of Shandong Province, Jinan, 250353 Shandong (China)

2010-06-15

318

Adsorbed natural gas storage with activated carbons made from Illinois coals and scrap tires  

USGS Publications Warehouse

Activated carbons for natural gas storage were produced from Illinois bituminous coals (IBC-102 and IBC-106) and scrap tires by physical activation with steam or CO2 and by chemical activation with KOH, H3PO4, or ZnCl2. The products were characterized for N2-BET area, micropore volume, bulk density, pore size distribution, and volumetric methane storage capacity (Vm/Vs). Vm/Vs values for Illinois coal-derived carbons ranged from 54 to 83 cm3/cm3, which are 35-55% of a target value of 150 cm3/cm3. Both granular and pelletized carbons made with preoxidized Illinois coal gave higher micropore volumes and larger Vm/Vs values than those made without preoxidation. This confirmed that preoxidation is a desirable step in the production of carbons from caking materials. Pelletization of preoxidized IBC-106 coal, followed by steam activation, resulted in the highest Vm/Vs value. With roughly the same micropore volume, pelletization alone increased Vm/Vs of coal carbon by 10%. Tire-derived carbons had Vm/Vs values ranging from 44 to 53 cm3/cm3, lower than those of coal carbons due to their lower bulk densities. Pelletization of the tire carbons increased bulk density up to 160%. However, this increase was offset by a decrease in micropore volume of the pelletized materials, presumably due to the pellet binder. As a result, Vm/Vs values were about the same for granular and pelletized tire carbons. Compared with coal carbons, tire carbons had a higher percentage of mesopores and macropores.

Sun, J.; Brady, T. A.; Rood, M. J.; Lehmann, C. M.; Rostam-Abadi, M.; Lizzio, A. A.

1997-01-01

319

New families of mesoporous materials  

Microsoft Academic Search

Mesoporous materials have been paid much attention in both scientific researches and practical applications. In this review, we focus on recent developments on preparation and functionalization of new families of mesoporous materials, especially non-siliceous mesoporous materials invented in our research group. Replica synthesis is known as the method to synthesize mesoporous materials composed of various elements using originally prepared mesoporous

Ajayan Vinu; Toshiyuki Mori; Katsuhiko Ariga

2006-01-01

320

Preparation of H 5PMo 10V 2O 40 (PMo 10V 2) catalyst immobilized on nitrogen-containing mesoporous carbon (N-MC) and its application to the methacrolein oxidation  

Microsoft Academic Search

Nitrogen-containing mesoporous carbon (N-MC) with high surface area (=938m2\\/g) and large pore volume (0.99cm3\\/g) was synthesized by a templating method using SBA-15 and polypyrrole as a templating agent and a carbon precursor, respectively. The N-MC was then modified to have a positive charge, and thus, to provide sites for the immobilization of the H5PMo10V2O40 (PMo10V2) catalyst. By taking advantage of

Heesoo Kim; Ji Chul Jung; Dong Ryul Park; Sung-Hyeon Baeck; In Kyu Song

2007-01-01

321

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

SciTech Connect

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.

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

1999-09-29

322

A highly sensitive electrochemical aptasensor for thrombin detection using functionalized mesoporous silica@multiwalled carbon nanotubes as signal tags and DNAzyme signal amplification.  

PubMed

In this work, we demonstrated a novel sensitive sandwich-type pseudobienzyme aptasensor for thrombin detection. Greatly amplified sensitivity was based on mesoporous silica-multiwalled carbon nanotube (mSiO2@MWCNT) nanocomposites as enhanced materials and a pseudobienzyme electrocatalytic system. Firstly, the mSiO2@MWCNT nanocomposites not only have good biocompatibility and a suitable microenvironment for stabilizing the aptamer assembly, but also can load large amounts of electron mediator thionine (Thi), platinum nanoparticles (PtNPs) and hemin/G-quadruplex bioelectrocatalytic complex. Moreover, in the presence of H2O2 in an electrolytic cell, the synergistic reaction of PtNPs and hemin/G-quadruplex bioelectrocatalyzed the reduction of H2O2, dramatically amplifying the response signals of electron mediator Thi and improving the sensitivity. Secondly, dendrimer functionalized reduced graphene oxide (PAMAM-rGO) as the biosensor platform enhanced the surface area for the immobilization of abundant primary aptamers as well as facilitated electron transfer from Thi to the electrode, thus amplifying the detection response. Using the above multiple effects, the approach showed a high sensitivity and a wider linearity for the detection of thrombin in the range between 0.0001 nM and 80 nM with a detection limit of 50 fM. This new design avoided the fussy labeling process and the spatial distribution of each sequentially acting enzyme, which provided an ideal candidate for the development of a sensitive and simple bioanalytical platform. PMID:24081001

Zhang, Juan; Chai, Yaqin; Yuan, Ruo; Yuan, Yali; Bai, Lijuan; Xie, Shunbi

2013-10-15

323

SORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBONS  

EPA Science Inventory

The mechanisms and rate of elemental mercury (HgO) capture by activated carbons have been studied using a bench-scale apparatus. Three types of activated carbons, two of which are thermally activated (PC-100 and FGD) and one with elemental sulfur (S) impregnated in it (HGR), were...

324

Mechanisms of Activated Carbon Degradation by Perspiration.  

National Technical Information Service (NTIS)

Amino acids harm the adsorption capacity of a carbon more than lactic or formic acid. Water can plug up carbon micropores. This water can be removed in a drying oven. In tests, the more harmful chemicals to adsorption capacity of an activated carbon were ...

L. L. Pytlewski

1976-01-01

325

Carbons prepared from coffee grounds by H3PO4 activation: characterization and adsorption of methylene blue and Nylosan Red N-2RBL.  

PubMed

Activated carbons were prepared by the pyrolysis of coffee grounds impregnated by phosphoric acid at 450 degrees C for different impregnation ratios: 30, 60, 120 and 180 wt.%. Materials were characterized for their surface chemistry by elemental analysis, "Boehm titrations", point of zero charge measurements, Infrared spectroscopy, thermogravimetric analysis (TGA); as well as for their porous and morphological structure by Scanning Electron Microscopy (SEM) and nitrogen adsorption at 77K. The impregnation ratio was found to govern the porous structure of the prepared activated carbons. Low impregnation ratios (<120 wt.%) led to essentially microporous and acidic activated carbons whereas high impregnation ratios (>120 wt.%) yielded to essentially mesoporous carbons with specific surface areas as high as 925 m(2)g(-1), pore volume as large as 0.7 cm(3)g(-1), and neutral surface. The activated carbons prepared from coffee grounds were compared to a commercial activated carbon (S(BET) approximately 1400 m(2)g(-1)) for their adsorption isotherms of methylene blue and "Nylosan Red N-2RBL", a cationic and anionic (azo) dye respectively. The mesoporous structure of the material produced at 180 wt.% H(3)PO(4) ratio was found to be appropriate for an efficient sorption of the latter azo dye. PMID:19942347

Reffas, A; Bernardet, V; David, B; Reinert, L; Lehocine, M Bencheikh; Dubois, M; Batisse, N; Duclaux, L

2009-10-30

326

Comparison between activated carbon, carbon xerogel and carbon nanotubes for the adsorption of the antibiotic ciprofloxacin  

Microsoft Academic Search

A comparison was made for the adsorption capacity of ciprofloxacin (CPX) on three types of carbon-based materials: activated carbon, carbon nanotubes and carbon xerogel. The obtained samples were characterised by adsorption of N2 at ?196°C, determination of the point of zero charge and by temperature programmed desorption. The Langmuir and Freundlich models were used to describe the equilibrium isotherms obtained.

S. A. C. Carabineiro; T. Thavorn-amornsri; M. F. R. Pereira; P. Serp; J. L. Figueiredo

327

CO oxidation over gold nanocatalyst confined in mesoporous silica  

Microsoft Academic Search

Au nanoparticles embedded within mesoporous silica particles have been prepared and used as catalysts for CO oxidation. The silane APTS (H2N(CH2)3-Si(OMe)3) was used to surface-functionalize mesoporous silica in a direct method. The functionalized mesoporous silica was used to absorb the gold precursor AuCl4? and gold nanoparticles were formed inside the nanochannels after chemical reduction. The catalysts were activated by calcinations,

Yu-Shan Chi; Hong-Ping Lin; Chung-Yuan Mou

2005-01-01

328

Adsorptive removal of hydrophobic organic compounds by carbonaceous adsorbents: a comparative study of waste-polymer-based, coal-based activated carbon, and carbon nanotubes.  

PubMed

Adsorption of the hydrophobic organic compounds (HOCs) trichloroethylene (TCE), 1,3-dichlorobenzene (DCB), 1,3-dinitrobenzene (DNB) and gamma-hexachlorocyclohexane (HCH) on five different carbonaceous materials was compared. The adsorbents included three polymer-based activated carbons, one coal-based activated carbon (F400) and multiwalled carbon nanotubes (MWNT). The polymer-based activated carbons were prepared using KOH activation from waste polymers: polyvinyl chloride (PVC), polyethyleneterephthalate (PET) and tire rubber (TR). Compared with F400 and MWNT, activated carbons derived from PVC and PET exhibited fast adsorption kinetics and high adsorption capacity toward the HOCs, attributed to their extremely large hydrophobic surface area (2700 m2/g) and highly mesoporous structures. Adsorption of small-sized TCE was stronger on the tire-rubber-based carbon and F400 resulting from the pore-filling effect. In contrast, due to the molecular sieving effect, their adsorption on HCH was lower. MWNT exhibited the lowest adsorption capacity toward HOCs because of its low surface area and characteristic of aggregating in aqueous solution. PMID:23520861

Lian, Fei; Chang, Chun; Du, Yang; Zhu, Lingyan; Xing, Baoshan; Liu, Chang

2012-01-01

329

Biochar as a precursor of activated carbon  

Microsoft Academic Search

Biochar was evaluated as a precursor of activated carbon. This product was produced by chemical activation using potassium\\u000a hydroxide. The effects of operating conditions of activation process, such as temperature, activating agent to biochar mass\\u000a ratio, and nitrogen flow rate, on the textural and chemical properties of the product were investigated. Activated carbon\\u000a produced by this method has internal surface

R. Azargohar; A. K. Dalai

2006-01-01

330

Ultrafine tin nanocrystallites encapsulated in mesoporous carbon nanowires: scalable synthesis and excellent electrochemical properties for rechargeable lithium ion batteries.  

PubMed

A morphology-conserved transformation yields Sn@C nanowires (UTP@CW, ?21 wt% carbon and ?77 wt% tin) with a high encapsulation density of ultrafine tin nanoparticles in porous carbon nanowires, which exhibit excellent reversible capacities and cycling performance for lithium ion batteries, especially at high current rates. PMID:20922234

Qiu, Yongcai; Yan, Keyou; Yang, Shihe

2010-10-04

331

Ordered mesoporous phenolic resins: highly versatile and ultra stable support materials.  

PubMed

Ordered mesoporous phenolic resins and carbons - an advanced class of ultra-stable mesoporous materials - offer potential applications in the field of catalysis, electrodes and adsorbents. This review gives an extensive overview of the main principles and the recent progress made in the synthesis of these innovative materials using the soft-template method. Furthermore, the versatility towards functionalization and the incorporation of hetero-atoms in the organic framework of the mesoporous resins and carbons are considered. Finally, the broad range of potential applications is discussed and future perspectives in the field of mesoporous polymers and carbons are given. PMID:22525791

Muylaert, Ilke; Verberckmoes, An; De Decker, Jeroen; Van Der Voort, Pascal

2012-04-06

332

Particle-size-dependent toxicity and immunogenic activity of mesoporous silica-based adjuvants for tumor immunotherapy.  

PubMed

Conventionally used adjuvants alone are insufficient for triggering cell-mediated immunity, although they have been successfully developed to elicit protective antibody responses in some vaccines. Here, with the aim of eliciting cell-mediated immunity, pathogen-associated molecular patterns (PAMPs) were immobilized with apatite within the pores and on the surface of mesoporous silica (MS) with particle sizes from 30 to 200nm to prepare novel MS-Ap-PAMP adjuvants, which showed cell-mediated anti-tumor immunity that was markedly improved compared to commercial alum adjuvant in vitro and in vivo. The toxicity and antitumor immunity of the MS-Ap-PAMP adjuvants were evaluated in vitro and in vivo. MS with a particle size of 200nm showed minimum in vitro cytotoxicity to NIH3T3 cells, particularly at concentrations no higher than 100?gml(-1). In particular, apatite precipitation within the pores and on the surface of MS decreased the in vitro cytotoxicity of MS particles. The MS-Ap-PAMP adjuvants showed the maximum in vitro immunogenic activity among original culture medium, PAMP and alum-PAMP. Moreover, injection of the MS-Ap-PAMP adjuvant in combination with liquid-nitrogen-treated tumor tissue (derived from Lewis lung carcinoma cells) into C57BL/6 mice markedly inhibited in vivo tumor recurrence and the development of rechallenged tumor compared to those with commercial alum adjuvant. The MS-Ap-PAMP adjuvant contributed to the elicitation of a potent systemic antitumor immunity without obvious toxicity in vivo. PMID:23541601

Wang, Xiupeng; Li, Xia; Ito, Atsuo; Sogo, Yu; Ohno, Tadao

2013-03-26

333

Ionic liquid-functionalized SBA15 mesoporous material: efficient heterogeneous catalyst in versatile organic reactions  

Microsoft Academic Search

Ionic liquid-functionalized mesoporous materials exhibited high catalytic activity in versatile organic reactions, such as\\u000a cycloaddition of carbon dioxide (CO2) with epoxide, aza-Michael addition of amines to ?, ?-unsaturated carbonyl compounds, and the Biginelli reaction of aldehyde, ethyl acetoacetate and urea. Recycling of the catalyst\\u000a in these reactions could be carried out and the catalyst used at least five times without

Li-Wen Xu; Ming-Song Yang; Jian-Xiong Jiang; Hua-Yu Qiu; Guo-Qiao Lai

2007-01-01

334

Activated carbons prepared from phosphoric acid activation of grain sorghum  

Microsoft Academic Search

The production of activated carbons from grain sorghum with phosphoric acid activation has been studied by means of two processes, i.e., one-stage and two-stage. The former comprises simultaneous carbonization and activation after impregnation; the latter, the carbonization of the precursor at 300 °C for 15 min, followed by the activation of the resultant char after impregnation with phosphoric acid. The

Yulu Diao; W. P Walawender; L. T Fan

2002-01-01

335

N-Doped SiO 2\\/TiO 2 mesoporous nanoparticles with enhanced photocatalytic activity under visible-light irradiation  

Microsoft Academic Search

Mesoporous nanocrystalline N-doped SiO2\\/TiO2 visible-light photocatalysts were prepared by treating SiO2\\/TiO2 xerogels in a flow of nitrogen gas bubbled through concentrated ammonia solution. Structural characterization and performance analysis results revealed that the addition of SiO2 remarkably altered the phase composition, specific surface area, microstructure, as well as the photocatalytic activity of N-doped TiO2. The presence of SiO2 in N-doped TiO2

Y. D. Hou; X. C. Wang; L. Wu; X. F. Chen; Z. X. Ding; X. X. Wang; X. Z. Fu

2008-01-01

336

Activated carbon for gas phase arsenic capture  

Microsoft Academic Search

Investigation of activated carbon as a multifunctional sorbent for trace metal capture is the focus of this study. In addition to mercury and halides, selenium and arsenic represent two of the most volatile trace species that remain in gas phase in substantial amounts. In this work, fundamental sorption characteristics of the activated carbon for arsenic removal from the gas phase

R. Jadhav; H. Gupta; S. Misro; R. Agnihotri; L. S. Fan

1999-01-01

337

ACTIVATED CARBON FROM LIGNITE FOR WATER TREATMENT  

Microsoft Academic Search

High concentrations of humate in surface water result in the formation of excess amounts of chlorinated byproducts during disinfection treatment. These precursors can be removed in water treatment prior to disinfection using powdered activated carbon. In the interest of developing a more cost-effective method for removal of humates in surface water, a comparison of the activities of carbons prepared from

Edwin S. Olson; Daniel J. Stepan

2000-01-01

338

Persulfate regeneration of trichloroethylene spent activated carbon.  

PubMed

The objective of this study was to demonstrate the regeneration of trichloroethylene (TCE) spent activated carbon using persulfate oxidation and iron activated persulfate (IAP) oxidation. Both processes resulted in decreases in the adsorbability of regenerated activated carbons. IAP was shown to rapidly degrade the aqueous TCE and causes a significant mineralization of the TCE. The release of chloride ions provided evidence of this. Persulfate oxidation mainly resulted in desorption of TCE from the activated carbon and only partial mineralization of the TCE through a carbon activated persulfate reaction mechanism. Concerning destruction of the TCE, in the regeneration test using persulfate, 30% of the original TCE was present in the solution and 9% remained on the activated carbon after the first regeneration cycle. In contrast, in the test that used IAP, it was observed that no TCE was present in the solution and only approximately 5% of the original TCE remained on the activated carbon after the first regeneration. Following the regeneration cycles, elemental analysis was carried out on the samples. BET surface area and EDS analysis showed some effects on the physico-chemical properties of the activated carbon such as a slight decrease in the surface area and the presence of iron precipitates on the carbon. PMID:19264399

Liang, Chenju; Lin, Ya-Ting; Shin, Wu-Hang

2009-02-12

339

Effects of Fe-doping on the photocatalytic activity of mesoporous TiO2 powders prepared by an ultrasonic method.  

PubMed

Highly photoactive nanocrystalline mesoporous Fe-doped TiO(2) powders were prepared by the ultrasonic-induced hydrolysis reaction of tetrabutyl titanate (Ti(OC(4)H(9))(4)) in a ferric nitrate aqueous solution (pH 5) without using any templates or surfactants. The as-prepared samples were characterized by thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), N(2) adsorption-desorption measurements, UV-visible adsorbance spectra (UV-vis) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities were evaluated by the photocatalytic oxidation of acetone in air. The results showed that all the Fe-doped TiO(2) samples prepared by ultrasonic methods were mesoporous nanocrystalline. A small amount of Fe(3+) ions in TiO(2) powders could obviously enhance their photocatalytic activity. The photocatalytic activity of Fe-doped TiO(2) powders prepared by this method and calcined at 400 degrees C exceeded that of Degussa P25 (P25) by a factor of more than two times at an optimal atomic ratio of Fe to Ti of 0.25. The high activities of the Fe-doped TiO(2) powders could be attributed to the results of the synergetic effects of Fe-doping, large BET specific surface area and small crystallite size. PMID:16777319

Zhou, Minghua; Yu, Jiaguo; Cheng, Bei

2006-05-16

340

Catalytic Growth of Macroscopic Carbon Nanofibers Bodies with Activated Carbon  

SciTech Connect

Carbon-carbon composite of activated carbon and carbon nanofibers have been synthesized by growing Carbon nanofiber (CNF) on Palm shell-based Activated carbon (AC) with Ni catalyst. The composites are in an agglomerated shape due to the entanglement of the defective CNF between the AC particles forming a macroscopic body. The macroscopic size will allow the composite to be used as a stabile catalyst support and liquid adsorbent. The preparation of CNT/AC nanocarbon was initiated by pre-treating the activated carbon with nitric acid, followed by impregnation of 1 wt% loading of nickel (II) nitrate solutions in acetone. The catalyst precursor was calcined and reduced at 300 deg. C for an hour in each step. The catalytic growth of nanocarbon in C{sub 2}H{sub 4}/H{sub 2} was carried out at temperature of 550 deg. C for 2 hrs with different rotating angle in the fluidization system. SEM and N{sub 2} isotherms show the level of agglomeration which is a function of growth density and fluidization of the system. The effect of fluidization by rotating the reactor during growth with different speed give a significant impact on the agglomeration of the final CNF/AC composite and thus the amount of CNFs produced. The macrostructure body produced in this work of CNF/AC composite will have advantages in the adsorbent and catalyst support application, due to the mechanical and chemical properties of the material.

Abdullah, N.; Muhammad, I. S.; Hamid, S. B. Abd. [NANOCEN, Block A, Level 3, Institute of Postgraduate Studies, University of Malaya, 50603 Kuala Lumpur (Malaysia); Rinaldi, A. [NANOCEN, Block A, Level 3, Institute of Postgraduate Studies, University of Malaya, 50603 Kuala Lumpur (Malaysia); Inorganic Chemistry Department, Fritz-Haber Institute der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany); Su, D. S.; Schlogl, R. [Inorganic Chemistry Department, Fritz-Haber Institute der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)

2009-06-01

341

Sorption of boron trifluoride by activated carbons  

SciTech Connect

The sorption of born trifluoride on AG-3, SKT, SKT-3, SKT-7, SKT-4A, SKT-6A, and SKT-2B carbons was investigated. The sorption isotherms for both vapors and gas were determined volumetrically. The coefficients of two equations described the sorption of BF/sub 3/ in the sorption of BF/sub 3/ on active carbons. Heats of sorption of BF/sub 3/ on the activated carbons are shown and the sorption isotherms and temperature dependences of the equilibrium pressure of BF/sub 3/ for activated carbons were presented. The values of the heats of sorption indicated the weak character of the reaction of BF/sub 3/ with the surface of the carbons. The equations can be used for calculating the phase equilibrium of BF/sub 3/ on carbons in a wider range of temperatures and pressures.

Polevoi, A.S.; Petrenko, A.E.

1988-01-10

342

Characterization and utilization of mesoporous fertilizer plant waste carbon for adsorptive removal of dyes from aqueous solution  

Microsoft Academic Search

This paper presents the physico-chemical characteristics of low-cost fertilizer plant waste carbon (WC) for the adsorption of different dyes. The particle size analysis showed an average particle size of 167.35?m. Proximate and CHN analysis showed the presence of high amount of carbon in WC. Bulk density and heating value of WC were found to be 308.03kg\\/m3 and 22.3MJ\\/kg, respectively. The

I. D. Mall; V. C. Srivastava; G. V. A. Kumar; I. M. Mishra

2006-01-01

343

Pore structure analysis of activated carbon fiber by microdomain-based model.  

PubMed

The pore structures of commercial pitch and PAN-based activated carbon fibers (ACFs) were investigated. The pore size and pore size distribution of pitch-based ACFs were measured by nitrogen adsorption isotherms and 129Xe NMR spectroscopy and compared with each other. Scanning tunneling microscopy showed that the ACFs were composed of spherical microdomain units the size of a few nanometers. The activation mechanism of ACFs was considered and explained by novel hypothesis; the concept of microdomain structure of ACFs was considered and explained to overcome limitation of the conventional fractal hypothesis. Whereas micropores were generated on each microdomain, the origin of mesopores was interdomain pores, resulting from the microdomain hypothesis. PMID:19344158

Shiratori, Nanako; Lee, Kyung Jin; Miyawaki, Jin; Hong, Seong-Hwa; Mochida, Isao; An, Bai; Yokogawa, Kiyoshi; Jang, Jyongsik; Yoon, Seong-Ho

2009-07-01

344

Influence of synthesis conditions and mesoporous structures on the gold nanoparticles supported on mesoporous silica hosts  

SciTech Connect

Loading gold on mesoporous materials via different methods has been actively attempted in the literature, but the knowledge about the influences of synthesis details and different mesoporous structures on the size and thermal stability of gold nanoparticles supported on mesoporous hosts is still limited. In this study, Au/HMS, Au/MCM-41, Au/MCM-48, Au/SBA-15, and Au/SBA-16 samples were prepared by modifying a variety of mesoporous silicas by amine ligands followed by loading HAuCl4 and calcination. The influences of different amine ligands ((3-aminopropyl)triethoxysilane versus N-[3-(trimethoxysilyl)propyl]ethylenediamine), solvents (water versus ethanol), calcination temperatures (200 or 550 C), and mesoporous structures on the size of supported gold nanoparticles were systematically investigated employing nitrogen adsorption-desorption measurement, X-ray diffraction (XRD), diffuse reflectance UV-vis spectroscopy, and transmission electron microscopy (TEM). Interestingly, while big and irregular gold particles situate on MCM-48 with bicontinuous three-dimensional pore structure and relatively small pore size (2.4 nm) upon calcination at 550 C, homogeneous and small gold nanoparticles maintain inside SBA-15 with one-dimensional pore structure and relatively big pore size (6.8 nm). Apparently, the pore structure and pore size of mesoporous silica hosts play a key role in determining the size and thermal stability of the supported gold nanoparticles. Our results may provide some useful clues for the rational design of supported metal catalysts by choosing suitable mesoporous hosts.

Lee, Byunghwan [Korea Institute of Industrial Technology, ChonAn, Korea; Ma, Zhen [ORNL; Zhang, Zongtao [ORNL; Park, Chulhwan [Kwangwoon University; Dai, Sheng [ORNL

2009-01-01

345

Adsorption characteristics of benzene on biosolid adsorbent and commercial activated carbons  

SciTech Connect

This study selected biosolids from a petrochemical wastewater treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl{sub 2}) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl{sub 2}-immersed biosolids pyrolyzed at 500{sup o}C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high. 18 refs., 9 figs., 3 tabs.

Hung-Lung Chiang; Kuo-Hsiung Lin; Chih-Yu Chen; Ching-Guan Choa; Ching-Shyung Hwu; Nina Lai [China Medical University, Taichung (Taiwan). Department of Risk Management

2006-05-15

346

Topological construction of mesoporous materials  

Microsoft Academic Search

Major advances in the field of ordered mesoporous materials have been achieved in topological structure definition at the meso phase, and macroscale levels (shape and morphology) using molecular control during mesoporous materials synthesis. Examples include the use of block copolymers for the preparation of mesoporous materials with large pore sizes ($?30 nm), the formation of mesoporous silica with 3D periodically

Dongyuan Zhao; Yang Peidong; Huo Qisheng; Chmelka Bradley F; Stucky Galen D

1998-01-01

347

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

SciTech Connect

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{sub 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. -- Graphical abstract: Proximal-C-A-SBA-15 with a proximal acid-base distance and maximum-C-A-SBA-15 with a maximum acid-base distance were synthesized by immobilizing lysine onto carboxyl-SBA-15. Display Omitted Research highlights: {yields} Proximal-C-A-SBA-15 with a proximal acid-base distance. {yields} Maximum-C-A-SBA-15 with a maximum acid-base distance. {yields} Compared to maximum-C-A-SBA-15, proximal-C-A-SBA-15 was more active toward aldol condensation reaction between acetone and various aldehydes.

Yu Xiaofang [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Yu Xiaobo [China Pharmaceutical University, Nanjing 210009 (China); Wu Shujie; Liu Bo; Liu Heng [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Guan Jingqi, E-mail: guanjq@jlu.edu.c [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China); Kan Qiubin, E-mail: catalysischina@yahoo.com.c [College of Chemistry, Jilin University, Jiefang Road 2519, Changchun 130023 (China)

2011-02-15

348

Twin polymerization at spherical hard templates: an approach to size-adjustable carbon hollow spheres with micro- or mesoporous shells.  

PubMed

Kitset hollow spheres: The combination of twin polymerization with hard templates makes hollow carbon spheres (HCSs) with tailored properties easily accessible. The thickness and pore texture of the HCS shells and also the diameter of the spherical cavity can be varied. The application potential of synthesized HCS is substantiated by an excellent cycling stability of lithium-sulfur batteries. PMID:23620268

Böttger-Hiller, Falko; Kempe, Patrick; Cox, Gerhard; Panchenko, Alexander; Janssen, Nicole; Petzold, Albrecht; Thurn-Albrecht, Thomas; Borchardt, Lars; Rose, Marcus; Kaskel, Stefan; Georgi, Colin; Lang, Heinrich; Spange, Stefan

2013-04-25

349

Selective oxidative activation of isobutane on a novel vanadium-substituted bimodal mesoporous oxide V-UVM-7  

Microsoft Academic Search

New vanado-silicates with a bimodal mesoporous system (V-UVM-7) and high vanadium contents (Si\\/V?7) have been prepared by a modification of the so-called atrane method. Its morphology consists of aggregation of nano-particles with V-MCM-41 structure, creating a second broader porous system in their interparticle space. Its structure allows to incorporate a high V contents into tetrahedral sites of the framework while

L. J. Huerta; P. Amorós; D. Beltrán-Porter; V. Cortés Corberán

2006-01-01

350

Recover VOCs via adsorption on activated carbon  

SciTech Connect

One of the most effective methods of controlling emissions of volatile organic compounds (VOCs) is also one of the most economical--adsorption, usually using activated carbon as the adsorbent. This process is cost-effective because it is typically able to recover many VOCs for reuse. A particularly common application of carbon adsorption for VOC control is solvent recovery. In general, solvent recovery via carbon adsorption is a logical consideration for any industrial process exhausting sizable quantities of valuable solvent (subject, of course, to the solvent's suitability for adsorption by activated carbon, as discussed later). The most commonly recovered solvents include toluene; heptane; hexane; carbon tetrachloride; acetone; ethyl acetate; methyl ethyl ketone(MEK); naphthalene; and methylene chloride. Many other solvents are also suitable for recovery by carbon adsorption. A recent CEP article discussed the basics of carbon adsorption and application of the technology to water and wastewater treatment. This article takes an in-depth look at the use of activated carbon adsorption of the control of airborne VOC emissions and solvent recovery. It outlines how to decide if carbon adsorption is suitable for an application and then explains how to implement the technology.

Ruhl, M.J. (Dedert Corp., Olympia Falls, IL (United States). Solvent Recovery Div.)

1993-07-01

351

Effects of Carbon Coating and Pore Corrugation on Capillary Condensation of Nitrogen in SBA-15 Mesoporous Silica.  

PubMed

To examine the origin of an ink-bottle-like structure in SBA-15 formed by carbon coating and the effects of pore corrugation on capillary condensation and evaporation of a vapor in the cylindrical pores, we measured the adsorption isotherms of nitrogen at 77 K on 10 kinds of SBA-15 samples before and after a carbon coating process by the exposure to acetylene at 1073 K, as well as desorption scanning curves and subloops on the untreated samples. These SBA-15 samples were synthesized under the different conditions of initial SiO2/P123 ratio and hydrothermal treatment. SBA-15 with relatively large microporosity tends to form easily constrictions inside the main channels by the carbon coating. This strongly suggests that the rough pore walls of SBA-15 may induce the incomplete wetting of carbon layers on the pore walls to form the constrictions inside the cylindrical pores. A comparison of two subloops implies that the pores of SBA-15 synthesized with a SiO2/P123 ratio of 75 consist of an assembly of connecting domains of different diameters; that is, the pores are highly corrugated. For SBA-15 synthesized with a SiO2/P123 ratio of 60, the amplitude of the pore corrugation is significantly decreased by the prolonged hydrothermal treatment at 373 K. On the other hand, for SBA-15 synthesized with a SiO2/P123 ratio of 45, the amplitude of the corrugation is negligibly small, although the cylindrical pores are interconnected through narrow necks with each other. It is found that the smaller the amplitude of the pore corrugation, the smaller the width of the hysteresis loop. PMID:23977846

Morishige, Kunimitsu

2013-09-11

352

Fabrication of mesoporous titania membrane of dual-pore system and its photocatalytic activity and dye-sensitized solar cell performance.  

PubMed

We report the fabrication of a novel titania membrane of the dual-pore system that is strategically designed and prepared by a two-step replication process and sol-gel reaction. The primary nanoporous channel structure is fabricated by the cage-like PMMA template (CPT) obtained from the nanoporous alumina membrane and the secondary mesoporous structure is formed by the sol-gel reaction of the lyotropic precursor solution within the CPT. Furthermore the mesoporous titania membrane (MTM) frame consists of the titania nanoparticles of 10-12 nm in diameter. Morphology and structural properties of the MTM are investigated by field emission scanning electron microscopy, high resolution transmission electron microscopy, x-ray diffraction and Brunauer-Emmett-Teller surface area. The photocatalytic activity and the solar energy properties of the MTM are characterized by UV-vis spectrophotometer, spectrofluorometer and photoinduced I-V measurement. The photocatalytic test indicates that the MTM has higher efficiency than the commercial P25 with a good recyclability due to its large-scale membrane style and the preliminary result on the solar cell application shows a solar energy conversion efficiency of 3.35% for the dye-sensitized solar cell utilizing the MTM. PMID:21613684

Oh, Seung-Lim; Choi, Kyong-Hoon; Im, Ji-Eun; Wang, Kang-Kyun; Yaung, Hae-Yong; Kim, Kyungkon; Kim, Yong-Rok

2011-05-25

353

Environmental Study of an Activated Carbon Plant.  

National Technical Information Service (NTIS)

This report is a summary of the environmental aspects arising from the production of activated carbon. The methods for pollution control are specified and the emissions and predicted ambient concentrations given. Recommendations are made to achieve satisf...

P. Clayton S. C. Wallin

1978-01-01

354

Transport properties of activated carbon fibers.  

National Technical Information Service (NTIS)

The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m(sup 2)/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the therm...

S. L. di Vittorio M. S. Dresselhaus M. Endo J. P. Issi L. Piraux

1990-01-01

355

Preparation of oil palm empty fruit bunch-based activated carbon for removal of 2,4,6-trichlorophenol: optimization using response surface methodology.  

PubMed

The effects of three preparation variables: CO(2) activation temperature, CO(2) activation time and KOH:char impregnation ratio (IR) on the 2,4,6-trichlorophenol (2,4,6-TCP) uptake and carbon yield of the activated carbon prepared from oil palm empty fruit bunch (EFB) were investigated. Based on the central composite design, two quadratic models were developed to correlate the three preparation variables to the two responses. The activated carbon preparation conditions were optimized using response surface methodology by maximizing both the 2,4,6-TCP uptake and activated carbon yield within the ranges studied. The optimum conditions for preparing activated carbon from EFB for adsorption of 2,4,6-TCP were found as follows: CO(2) activation temperature of 814 degrees C, CO(2) activation time of 1.9h and IR of 2.8, which resulted in 168.89 mg/g of 2,4,6-TCP uptake and 17.96% of activated carbon yield. The experimental results obtained agreed satisfactorily with the model predictions. The activated carbon prepared under optimum conditions was mesoporous with BET surface area of 1141 m(2)/g, total pore volume of 0.6 cm(3)/g and average pore diameter of 2.5 nm. The surface morphology and functional groups of the activated carbon were respectively determined from the scanning electron microscopy and Fourier transform infrared analysis. PMID:18977086

Hameed, B H; Tan, I A W; Ahmad, A L

2008-09-21

356

Mesoporous Silica Nanoparticle-Stabilized and Manganese-Modified Rhodium Nanoparticles as Catalysts for Highly Selective Synthesis of Ethanol and Acetaldehyde from Syngas  

SciTech Connect

Well-defined and monodispersed rhodium nanoparticles as small as approximately 2?nm were encapsulated in?situ and stabilized in a mesoporous silica nanoparticle (MSN) framework during the synthesis of the mesoporous material. Although both the activity and selectivity of MSN-encapsulated rhodium nanoparticles in CO hydrogenation could be improved by the addition of manganese oxide as expected, the carbon selectivity for C2 oxygenates (including ethanol and acetaldehyde) was unprecedentedly high at 74.5?% with a very small amount of methanol produced if rhodium nanoparticles were modified by manganese oxide with very close interaction.

Huang, Yulin; Deng, Weihua; Guo, Enruo; Chung, Po-Wen; Chen, Senniang; Trewyn, Brian; Brown, Robert; Lin, Victor

2012-03-30

357

USE OF ACTIVATED CARBON FOR SOIL BIOREMEDIATION  

Microsoft Academic Search

The use of activated carbon may help overcome the toxicity of organic pollutants to microbes and plants during soil bioremediation.\\u000a Experiments were conducted with 3,4-dichloroaniline (DCA), 2,4,6-trinitrotoluene (TNT), and polychlorinated biphenyls (PCB)\\u000a to demonstrate that activated carbon (AC) can reduce the toxicity of readily available chemicals in soil by transferring them\\u000a to a less toxic soil fraction.

Galina K. Vasilyeva; Elena R. Strijakova; Patrick J. Shea

358

Catalytic decomposition of methane over activated carbon  

Microsoft Academic Search

Methane decomposition over activated carbons was carried out in a fixed bed, quartz-tube flow reactor. The kinetics of methane decomposition and surface properties changes before and after reaction was investigated. As a non-carbon based material, active alumina was also used to compare and understand the catalytic decomposition mechanism of methane over different materials. A reaction order of 0.5 is obtained

Zongqing Bai; Haokan Chen; Baoqing Li; Wen Li

2005-01-01

359

Fixation of potassium aurocyanide on active carbons  

Microsoft Academic Search

Active carbons of different origins (ex-coconut shell, ex-coal, ex-peat and ex-wood) have been used as adsorbents of potassium aurocyanide. Various treatments were applied to the active carbons: heat treatment at 800 °C, heat treatment at 800 °C followed by HCl (11) washing, heat treatment at 650 °C, washing with HCl 10%, esterification with methanol, oxidation with nitric acid and extraction

Eugène Papirer; Anundo Polania-Leon; Jean-Baptiste Donnet; Philippe Montagnon

1995-01-01

360

Adsorption of herbicides using activated carbons  

SciTech Connect

This paper describes the results of research in which novel activated carbons have been examined for their efficacy in water treatment and, specifically, for the adsorption of a common herbicide and wood preservative, sodium pentachlorophenolate. To place this work in context, the introduction will discuss first some of the considerations of using activated carbons for water treatment, and then certain aspects of the authors research that has led to this particular topic.

Derbyshire, F.; Jagtoyen, M.; Lafferty, C.; Kimber, G. [Univ. of Kentucky, Lexington, KY (United States)

1996-12-31

361

A highly ordered cubic mesoporous silica/graphene nanocomposite  

NASA Astrophysics Data System (ADS)

A highly ordered cubic mesoporous silica (KIT-6)/graphene nanocomposite and 2D KIT-6 nanoflakes were synthesized using a novel synthesis methodology. The non-ionic triblock copolymer, P123, played a dual role as a structure-directing agent in the formation of the cubic mesoporous structure and as a cross-linking agent between mesoporous silica and graphene. The prepared (KIT-6)/graphene nanocomposite could act as a template for the preparation of mesoporous material/graphene nanocomposites.A highly ordered cubic mesoporous silica (KIT-6)/graphene nanocomposite and 2D KIT-6 nanoflakes were synthesized using a novel synthesis methodology. The non-ionic triblock copolymer, P123, played a dual role as a structure-directing agent in the formation of the cubic mesoporous structure and as a cross-linking agent between mesoporous silica and graphene. The prepared (KIT-6)/graphene nanocomposite could act as a template for the preparation of mesoporous material/graphene nanocomposites. Electronic supplementary information (ESI) available: S1: TEM images of disordered mesoporous silica/graphene nanocomposite; S2: TEM images of KIT-6/GO nanocomposite; S3: Thermogravimetric analysis of KIT-6/GO and KG-400-700; S4: SEM and TEM images of KIT-6; S5: Low angle XRD, Raman spectra, N2 adsorption isotherms, pore size distribution and photographic images of the prepared samples; S6: TEM image and N2 adsorption isotherms of mesoporous carbon/graphene nanocomposite; S7: XPS C1s spectra of the prepared samples. See DOI: 10.1039/c3nr03108j

Lee, Chang-Wook; Roh, Kwang Chul; Kim, Kwang-Bum

2013-09-01

362

Core–shell structured mesoporous silica nanoparticles equipped with pyrene-based chemosensor: Synthesis, characterization, and sensing activity towards Hg(II)  

Microsoft Academic Search

In this paper, we construct core–shell structured mesoporous silica nanoparticles with spherical SiO2 as the core and mesoporous silica as the shell, offering both large surface-area-to-volume-ratio and short channels. With this core–shell structured mesoporous silica nanoparticles as supporting medium, a chemosensor of pyrene, owing advantages of large Stokes shift, high quantum yield and excellent photostability, is grafted into the channels

Nai-Bo Zhang; Jian-Jun Xu; Chen-Guang Xue

2011-01-01

363

Nanospace engineering of KOH activated carbon  

NASA Astrophysics Data System (ADS)

This paper demonstrates that nanospace engineering of KOH activated carbon is possible by controlling the degree of carbon consumption and metallic potassium intercalation into the carbon lattice during the activation process. High specific surface areas, porosities, sub-nanometer (<1 nm) and supra-nanometer (1-5 nm) pore volumes are quantitatively controlled by a combination of KOH concentration and activation temperature. The process typically leads to a bimodal pore size distribution, with a large, approximately constant number of sub-nanometer pores and a variable number of supra-nanometer pores. We show how to control the number of supra-nanometer pores in a manner not achieved previously by chemical activation. The chemical mechanism underlying this control is studied by following the evolution of elemental composition, specific surface area, porosity, and pore size distribution during KOH activation and preceding H3PO4 activation. The oxygen, nitrogen, and hydrogen contents decrease during successive activation steps, creating a nanoporous carbon network with a porosity and surface area controllable for various applications, including gas storage. The formation of tunable sub-nanometer and supra-nanometer pores is validated by sub-critical nitrogen adsorption. Surface functional groups of KOH activated carbon are studied by microscopic infrared spectroscopy.

Romanos, J.; Beckner, M.; Rash, T.; Firlej, L.; Kuchta, B.; Yu, P.; Suppes, G.; Wexler, C.; Pfeifer, P.

2012-01-01

364

Competitive adsorption of phenolic compounds from aqueous solution using sludge-based activated carbon.  

PubMed

Preparation of activated carbon from sewage sludge is a promising approach to produce cheap and efficient adsorbent for pollutants removal as well as to dispose of sewage sludge. The first objective of this study was to investigate the physical and chemical properties (BET surface area, ash and elemental content, surface functional groups by Boehm titration and weight loss by thermogravimetric analysis) of the sludge-based activated carbon (SBAC) so as to give a basic understanding of its structure and to compare to those of two commercial activated carbons, PICA S23 and F22. The second and main objective was to evaluate the performance of SBAC for single and competitive adsorption of four substituted phenols (p-nitrophenol, p-chlorophenol, p-hydroxy benzoic acid and phenol) from their aqueous solutions. The results indicated that, despite moderate micropore and mesopore surface areas, SBAC had remarkable adsorption capacity for phenols, though less than PICA carbons. Uptake of the phenolic compound was found to be dependent on both the porosity and surface chemistry of the carbons. Furthermore, the electronegativity and the hydrophobicity of the adsorbate have significant influence on the adsorption capacity. The Langmuir and Freundlich models were used for the mathematical description of the adsorption equilibrium for single-solute isotherms. Moreover, the Langmuir-Freundlich model gave satisfactory results for describing multicomponent system isotherms. The capacity of the studied activated carbons to adsorb phenols from a multi-solute system was in the following order: p-nitrophenol > p-chlorophenol > PHBA > phenol. PMID:21970174

Mohamed, E F; Andriantsiferana, C; Wilhelm, A M; Delmas, H

365

Activated carbon for gas phase arsenic capture  

SciTech Connect

Investigation of activated carbon as a multifunctional sorbent for trace metal capture is the focus of this study. In addition to mercury and halides, selenium and arsenic represent two of the most volatile trace species that remain in gas phase in substantial amounts. In this work, fundamental sorption characteristics of the activated carbon for arsenic removal from the gas phase are investigated. Activated carbons with different structural properties are studied for their usefulness in removing arsenic species from flue gas. Arsenic oxide (As{sub 2}O{sub 3}) is used as the source of arsenic. Preliminary sorption studies indicate that arsenic removal occurs by physical adsorption, with increased capture by carbons with higher surface areas.

Jadhav, R.; Gupta, H.; Misro, S.; Agnihotri, R.; Fan, L.S.

1999-07-01

366

Activated carbons derived from coconut shells as high energy density cathode material for Li-ion capacitors  

NASA Astrophysics Data System (ADS)

In this manuscript, a dramatic increase in the energy density of ~ 69 Wh kg-1 and an extraordinary cycleability ~ 2000 cycles of the Li-ion hybrid electrochemical capacitors (Li-HEC) is achieved by employing tailored activated carbon (AC) of ~ 60% mesoporosity derived from coconut shells (CS). The AC is obtained by both physical and chemical hydrothermal carbonization activation process, and compared to the commercial AC powders (CAC) in terms of the supercapacitance performance in single electrode configuration vs. Li. The Li-HEC is fabricated with commercially available Li4Ti5O12 anode and the coconut shell derived AC as cathode in non-aqueous medium. The present research provides a new routine for the development of high energy density Li-HEC that employs a mesoporous carbonaceous electrode derived from bio-mass precursors.

Jain, Akshay; Aravindan, Vanchiappan; Jayaraman, Sundaramurthy; Kumar, Palaniswamy Suresh; Balasubramanian, Rajasekhar; Ramakrishna, Seeram; Madhavi, Srinivasan; Srinivasan, M. P.

2013-10-01

367

Activated carbons derived from coconut shells as high energy density cathode material for Li-ion capacitors  

PubMed Central

In this manuscript, a dramatic increase in the energy density of ~ 69?Wh kg?1 and an extraordinary cycleability ~ 2000 cycles of the Li-ion hybrid electrochemical capacitors (Li-HEC) is achieved by employing tailored activated carbon (AC) of ~ 60% mesoporosity derived from coconut shells (CS). The AC is obtained by both physical and chemical hydrothermal carbonization activation process, and compared to the commercial AC powders (CAC) in terms of the supercapacitance performance in single electrode configuration vs. Li. The Li-HEC is fabricated with commercially available Li4Ti5O12 anode and the coconut shell derived AC as cathode in non-aqueous medium. The present research provides a new routine for the development of high energy density Li-HEC that employs a mesoporous carbonaceous electrode derived from bio-mass precursors.

Jain, Akshay; Aravindan, Vanchiappan; Jayaraman, Sundaramurthy; Kumar, Palaniswamy Suresh; Balasubramanian, Rajasekhar; Ramakrishna, Seeram; Madhavi, Srinivasan; Srinivasan, M. P.

2013-01-01

368

Activated carbons derived from coconut shells as high energy density cathode material for Li-ion capacitors.  

PubMed

In this manuscript, a dramatic increase in the energy density of ~ 69?Wh kg(-1) and an extraordinary cycleability ~ 2000 cycles of the Li-ion hybrid electrochemical capacitors (Li-HEC) is achieved by employing tailored activated carbon (AC) of ~ 60% mesoporosity derived from coconut shells (CS). The AC is obtained by both physical and chemical hydrothermal carbonization activation process, and compared to the commercial AC powders (CAC) in terms of the supercapacitance performance in single electrode configuration vs. Li. The Li-HEC is fabricated with commercially available Li4Ti5O12 anode and the coconut shell derived AC as cathode in non-aqueous medium. The present research provides a new routine for the development of high energy density Li-HEC that employs a mesoporous carbonaceous electrode derived from bio-mass precursors. PMID:24141527

Jain, Akshay; Aravindan, Vanchiappan; Jayaraman, Sundaramurthy; Kumar, Palaniswamy Suresh; Balasubramanian, Rajasekhar; Ramakrishna, Seeram; Madhavi, Srinivasan; Srinivasan, M P

2013-10-21

369

Microwave-assisted regeneration of activated carbon.  

PubMed

Microwave heating was used in the regeneration of methylene blue-loaded activated carbons produced from fibers (PFAC), empty fruit bunches (EFBAC) and shell (PSAC) of oil palm. The dye-loaded carbons were treated in a modified conventional microwave oven operated at 2450 MHz and irradiation time of 2, 3 and 5 min. The virgin properties of the origin and regenerated activated carbons were characterized by pore structural analysis and nitrogen adsorption isotherm. The surface chemistry was examined by zeta potential measurement and determination of surface acidity/basicity, while the adsorptive property was quantified using methylene blue (MB). Microwave irradiation preserved the pore structure, original active sites and adsorption capacity of the regenerated activated carbons. The carbon yield and the monolayer adsorption capacities for MB were maintained at 68.35-82.84% and 154.65-195.22 mg/g, even after five adsorption-regeneration cycles. The findings revealed the potential of microwave heating for regeneration of spent activated carbons. PMID:22728787

Foo, K Y; Hameed, B H

2012-05-22

370

Enhanced visible-light-driven photocatalytic activity of mesoporous TiO(2-x)N(x) derived from the ethylenediamine-based complex.  

PubMed

A facile solvent evaporation induced self-assembly (SEISA) strategy was developed to synthesize mesoporous N-doped anatase TiO2 (SE-meso-TON) using a single organic complex precursor derived in situ from titanium butoxide and ethylenediamine in ethanol solution. After the evaporation of ethanol in a fume hood and subsequent calcinations at 450 °C, the obtained N-doped TiO2 (meso-TON) anatase was of finite crystallite size, developed porosity, large surface area (101 m(2) g(-1)) and extended light absorption in the visible region. This SE-meso-TON also showed superior photocatalytic activity to the SG-meso-TON anatase prepared via sol-gel synthesis. On the basis of characterization results from XRD, XPS, N2 adsorption-desorption and ESR, the enhanced visible-light-responsive photocatalytic activity of SE-meso-TON was assigned to its developed mesoporosity and reduced oxygen vacancies. PMID:23657366

Jiang, Zheng; Kong, Liang; Alenazey, Feraih Sh; Qian, Yangdong; France, Liam; Xiao, Tiancun; Edwards, Peter P

2013-06-21

371

Enhanced visible-light-driven photocatalytic activity of mesoporous TiO2-xNx derived from the ethylenediamine-based complex  

NASA Astrophysics Data System (ADS)

A facile solvent evaporation induced self-assembly (SEISA) strategy was developed to synthesize mesoporous N-doped anatase TiO2 (SE-meso-TON) using a single organic complex precursor derived in situ from titanium butoxide and ethylenediamine in ethanol solution. After the evaporation of ethanol in a fume hood and subsequent calcinations at 450 °C, the obtained N-doped TiO2 (meso-TON) anatase was of finite crystallite size, developed porosity, large surface area (101 m2 g-1) and extended light absorption in the visible region. This SE-meso-TON also showed superior photocatalytic activity to the SG-meso-TON anatase prepared via sol-gel synthesis. On the basis of characterization results from XRD, XPS, N2 adsorption-desorption and ESR, the enhanced visible-light-responsive photocatalytic activity of SE-meso-TON was assigned to its developed mesoporosity and reduced oxygen vacancies.

Jiang, Zheng; Kong, Liang; Alenazey, Feraih Sh.; Qian, Yangdong; France, Liam; Xiao, Tiancun; Edwards, Peter P.

2013-05-01

372

Recycle of silicate waste into mesoporous materials.  

PubMed

Template synthesis of porous carbon materials usually requires selective removal of template silica from the carbon/silica composites. It not only involves waste of valuable chemicals, but also poses significant environmental concerns including high waste treatment cost. Recycling of silicates released from such nanocasting methods is successfully performed for the first time to regenerate valuable mesoporous MCM and SBA type silica materials, which will not only help in saving valuable chemicals, but also in decreasing chemical waste, contributing in improvement of our environmental standards. This approach can thus improve cost effectiveness for the mass production of nanostructured carbon and others utilizing silica directed nanocasting method by recycling otherwise silicate waste into highly desirable valuable mesoporous silica. PMID:21417445

Kim, Jung Ho; Kim, Minwoo; Yu, Jong-Sung

2011-03-21

373

Preparation of diamine modified mesoporous silica on multi-walled carbon nanotubes for the adsorption of heavy metals in aqueous solution  

NASA Astrophysics Data System (ADS)

Diamine modified mesoporous silica on MWCNTs was firstly synthesized.The prepared adsorbent was characterized by various instrumental methods.The adsorption process using Cu(II) as a model was thoroughly investigated.This new adsorbent showed excellent adsorption efficiency for heavy metals.

Yang, Weijie; Ding, Ping; Zhou, Lei; Yu, Jingang; Chen, Xiaoqing; Jiao, Feipeng

2013-10-01

374

Enhanced photocatalytic activity of mesoporous and ordinary TiO 2 thin films by sulfuric acid treatment  

Microsoft Academic Search

Transparent anatase mesoporous TiO2 (MTiO2) and TiO2 nanometer thin films were prepared on soda-lime glass and fused quartz via the reverse micellar method and sol–gel method, respectively. The as-prepared MTiO2 and TiO2 films were then treated by dipping them in a H2SO4 solution. The MTiO2 and TiO2 films before and after surface acid treatment were characterized by X-ray photoelectron spectroscopy

Jimmy C Yu; Jiaguo Yu; Jincai Zhao

2002-01-01

375

Synthesis and catalytic applications of combined zeolitic/mesoporous materials  

PubMed Central

Summary In the last decade, research concerning nanoporous siliceous materials has been focused on mesoporous materials with intrinsic zeolitic features. These materials are thought to be superior, because they are able to combine (i) the enhanced diffusion and accessibility for larger molecules and viscous fluids typical of mesoporous materials with (ii) the remarkable stability, catalytic activity and selectivity of zeolites. This review gives an overview of the state of the art concerning combined zeolitic/mesoporous materials. Focus is put on the synthesis and the applications of the combined zeolitic/mesoporous materials. The different synthesis approaches and formation mechanisms leading to these materials are comprehensively discussed and compared. Moreover, Ti-containing nanoporous materials as redox catalysts are discussed to illustrate a potential implementation of combined zeolitic/mesoporous materials.

Vernimmen, Jarian; Cool, Pegie

2011-01-01

376

Comparative study of heavy metal ions sorption onto activated carbon, carbon nanotubes, and carbon-encapsulated magnetic nanoparticles  

Microsoft Academic Search

The paper presents the advantages and limitations of heavy metals sorption onto three different carbon materials: activated carbon, carbon nanotubes, and carbon-encapsulated magnetic nanoparticles. Studied carbon sorbents differed with the grain size, crystallinity, and active surface area, which were derived from electron microscopy, Raman spectroscopy, and methylene blue adsorption, respectively. Detailed sorption studies were based on two model metal ions,

Krystyna Pyrzy?ska; Micha? Bystrzejewski

2010-01-01

377

TWO-STAGE GRANULAR ACTIVATED CARBON TREATMENT  

EPA Science Inventory

Two 6.3 l/sec (0.15 mgd), two-stage, packed-bed, downflow granular activated carbon pilot plants were operated continuously for 33 months using unfiltered and unchlorinated activated sludge plant effluent. The main objective of the study was to compare the performance of granular...

378

Adsorption of Mercuric Ion from Aqueous Solutions Using Activated Carbon  

Microsoft Academic Search

Activated carbon (AC) was prepared from hazelnut shells using two steps of carbonization followed by steam activation. Methylene blue dye was used as a probe for evaluation of the prepared activated carbon. In order to have a better comparison, a commercial grade of activated carbon (powdered) obtained from the Merck Company has also been used in this research as standard.

R. Ansari Khalkhali; R. Omidvari

379

Reprocessing of used tires into activated carbon and other products  

Microsoft Academic Search

Landfilling used tires which are generated each year in the US is increasingly becoming an unacceptable solution. A better approach, from an environmental and economic standpoint, is to thermally reprocess the tires into valuable products such as activated carbon, other solid carbon forms (carbon black, graphite, and carbon fibers), and liquid fuels. In this study, high surface area activated carbons

Hsisheng Teng; Michael A. Serio; Marek A. Wojtowicz; Rosemary Bassilakis; Peter R. Solomon

1995-01-01

380

Influence of CO{sub 2} activation on hydrogen storage behaviors of platinum-loaded activated carbon nanotubes  

SciTech Connect

In this work, platinum (Pt) metal loaded activated multi-walled carbon nanotubes (MWNTs) were prepared with different structural characteristics for hydrogen storage applications. The process was conducted by a gas phase CO{sub 2} activation method at 1200 {sup o}C as a function of the CO{sub 2} flow time. Pt-loaded activated MWNTs were also formulated to investigate the hydrogen storage characteristics. The microstructures of the Pt-loaded activated MWNTs were characterized by XRD and TEM measurements. The textural properties of the samples were analyzed using N{sub 2} adsorption isotherms at 77 K. The BET, D-R, and BJH equations were used to observe the specific surface areas and the micropore and mesopore structures. The hydrogen storage capacity of the Pt-loaded activated MWNTs was measured at 298 K at a pressure of 100 bar. The hydrogen storage capacity was increased with CO{sub 2} flow time. It was found that the micropore volume of the activated MWNTs plays a key role in the hydrogen storage capacity. -- Graphical abstract: The hydrogen storage capacities of the Pt-loaded activated MWNTs as a function of CO{sub 2} flow time are described. Display Omitted

Lee, Seul-Yi [Department of Chemistry, Inha University, 253, Nam-gu, Incheon 402-751 (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.k [Department of Chemistry, Inha University, 253, Nam-gu, Incheon 402-751 (Korea, Republic of)

2010-12-15

381

Targeted thrombolysis by using of magnetic mesoporous silica nanoparticles.  

PubMed

Thrombolytics inevitably led to the risk of hemorrhagic complications due to their non-specific plasminogen activation in treatment of thrombosis. The aim of this study was to determine whether a kind of superparamagnetic mesoporous silica nanoparticle with expanded pore size could achieve effectively targeted thrombolysis. The magnetic mesoporous silica nanoparticles (M-MSNs) with the pore size of 6 nm were prepared by method of the surfactant templating on nano magnetic particles. We investigated the feasibility and efficacy of target thrombolysis with the resultant spheres through fibrin agarose plate assay (FAPA) and a dynamic flow system in vitro. It displayed a 30-fold enhancement of urokinase (UK) loading capacity over the particles without mesoporous layer or the magnetic spheres with mesopores of 3.7 nm. A sustained release behavior was observed due to its larger pore size, higher surface area and narrow mesopore channals contrast to non-mesoporous and small mesopore of 3.7 nm controls. Meanwhile, fibrin agarose plate assay revealed that UK/M-MSNs exhibited a more rapid growth rate of thrombolysis even lasting for 3 days. Additionally, flow model test in vitro suggested this kind of nanoparticle complex enhanced the thrombolysis efficacy by 3.5 fold over the same amount of native UK in 30 min. When compared to non-mesoporous and small mesopore controls, it also represented an extremely higher lysis efficiency (ANOVA, P < 0.01) and a shorter reperfusion time (ANOVA, P < 0.001). Such a magnetic mesoporous silica nanoparticle carrier was expected to be further studied for targeted thrombolytic therapy. PMID:22852472

Wang, Mingqi; Zhang, Jixi; Yuan, Ziming; Yang, Wenzhi; Wu, Qiang; Gu, Hongchen

2012-08-01

382

Effect of ultrasonic power on the structure of activated carbon and the activities of Ru/AC catalyst.  

PubMed

Ruthenium-based materials are the second-generation catalysts for ammonia synthesis. Ruthenium is less inhibited by ammonia, less sensitive to poisons, and more active than the traditional iron-based catalyst. The relatively high cost of Ru compared to that of iron requires a high dispersion of the metal on a suitable support. Carbon-supported Ru catalysts with promoters have been reported to be active for ammonia synthesis. The ultrasonic technique has been proven to be beneficial to the preparation of supported catalysts. In this paper, the effects of ultrasonic treatment on the surface texture, oxygen groups of activated carbon (AC) as well as ruthenium dispersion were investigated by the employments of N(2) physisorption, TPD-MS and CO chemisorption respectively. It have been shown that ash content in AC can be effectively eliminated by ultrasonic pretreatment, at the same time, the BET surface area and total pore volume are reduced, and the amount of the decomposable surface oxygen groups are decreased. Furthermore the ash content decrease and the mesopore surface area increase with the ultrasonic power increasing. The activities of a series of barium-potassium-promoted Ru/AC catalysts for ammonia synthesis were tested at 10,000 h(-1), 10.0 MPa and 400 degrees C. The results show that the activities of Ru/AC catalysts which were prepared by ultrasonic treatment are greatly increased, and the optimum pretreatment power is 100 W. The ash content of this carbon support is decreased from 1.39% to 1.15%. As a result, the catalytic activity is improved from 65.3 to 83.8 mmol g(-1) h(-1). PMID:16782146

Yu, Fengwen; Ji, Jianbing; Xu, Zhichao; Liu, Huazhang

2006-06-02

383

Record Methane Storage in Monolithic and Powdered Activated Carbons  

Microsoft Academic Search

The Alliance for Collaborative Research in Alternative Fuel Technology (ALL-CRAFT) has developed activated carbons from corn cob as adsorbent materials for methane gas storage by physisorption at low pressures. KOH activated carbons were compressed into carbon monolith using chemical binders. High pressure methane isotherms up to 250 bar at room temperature on monolithic and powdered activated carbons were measured gravimetrically

Yuchoong Soo; E. Nordwald; B. Hester; J. Romanos; B. Isaacson; D. Stalla; D. Moore; M. Kraus; J. Burress; E. Dohnke; P. Pfeifer

2010-01-01

384

Verified syntheses of mesoporous materials  

Microsoft Academic Search

A very large number of different synthesis approaches for the preparation of mesoporous materials has been reported in literature since the first development of ordered mesoporous materials in the 1990’s. Since then, the synthesis of advanced mesoporous materials has undergone an explosive growth. Moreover, this type of materials gains growing success in a wide variety of applications. For these reasons

V. Meynen; P. Cool; E. F. Vansant

2009-01-01

385

Dendrimer Templated Synthesis of One Nanometer Rh and Pt Particles Supported on Mesoporous Silica: Catalytic Activity for Ethylene and Pyrrole Hydrogenation.  

SciTech Connect

Monodisperse rhodium (Rh) and platinum (Pt) nanoparticles as small as {approx}1 nm were synthesized within a fourth generation polyaminoamide (PAMAM) dendrimer, a hyperbranched polymer, in aqueous solution and immobilized by depositing onto a high-surface-area SBA-15 mesoporous support. X-ray photoelectron spectroscopy indicated that the as-synthesized Rh and Pt nanoparticles were mostly oxidized. Catalytic activity of the SBA-15 supported Rh and Pt nanoparticles was studied with ethylene hydrogenation at 273 and 293 K in 10 torr of ethylene and 100 torr of H{sub 2} after reduction (76 torr of H{sub 2} mixed with 690 torr of He) at different temperatures. Catalysts were active without removing the dendrimer capping but reached their highest activity after hydrogen reduction at a moderate temperature (423 K). When treated at a higher temperature (473, 573, and 673 K) in hydrogen, catalytic activity decreased. By using the same treatment that led to maximum ethylene hydrogenation activity, catalytic activity was also evaluated for pyrrole hydrogenation.

Huang, Wenyu; Kuhn, John N.; Tsung, Chia-Kuang; Zhang, Yawen; Habas, Susan E.; Yang, Peidong; Somorjai, Gabor A.

2008-05-09

386

Production of active carbons from waste tyres––a review  

Microsoft Academic Search

A review of the production of activated carbons from waste tyres is presented. The effects of various process parameters, particularly, temperature and heating rate, on the pyrolysis stage are reviewed. The influence of activating conditions, physical and chemical, nature of the activation chemicals, on the active carbon properties are discussed. Under certain process conditions several active carbons with BET surface

Edward L. K. Mui; Danny C. K. Ko; Gordon McKay

2004-01-01

387

Study of NO adsorption on activated carbons  

Microsoft Academic Search

Activated carbons (ACs) with varied porous textures and surface chemistry were studied for NO removal under different test conditions at temperatures below 100°C. When oxygen is absent, there is almost no NO removal. When oxygen is present ACs act both as a catalyst for NO oxidation and as an adsorbent for NO adsorption. NO conversion is correlated with the presence

W. J. Zhang; S. Rabiei; A. Bagreev; M. S. Zhuang; F. Rasouli

2008-01-01

388

ACTIVATED CARBON TREATMENT OF KRAFT BLEACHING EFFLUENTS  

EPA Science Inventory

The removal of color and organic contaminants by adsorption on activated carbon from the effluent of a kraft pulp bleaching plant was investigated in a pilot plant. The caustic bleach effluent, which contains 80% of the color from pulp bleaching, was decolorized successfully when...

389

ENGINEERING BULLETIN: GRANULAR ACTIVATED CARBON TREATMENT  

EPA Science Inventory

Granular activated carbon (GAC) treatment is a physicochemical process that removes a wide variety of contaminants by adsorbing them from liquid and gas streams [1, p. 6-3]. This treatment is most commonly used to separate organic contaminants from water or air; however, it can b...

390

Low frequency sound propagation in activated carbon.  

PubMed

Activated carbon can adsorb and desorb gas molecules onto and off its surface. Research has examined whether this sorption affects low frequency sound waves, with pressures typical of audible sound, interacting with granular activated carbon. Impedance tube measurements were undertaken examining the resonant frequencies of Helmholtz resonators with different backing materials. It was found that the addition of activated carbon increased the compliance of the backing volume. The effect was observed up to the highest frequency measured (500 Hz), but was most significant at lower frequencies (at higher frequencies another phenomenon can explain the behavior). An apparatus was constructed to measure the effective porosity of the activated carbon as well as the number of moles adsorbed at sound pressures between 104 and 118 dB and low frequencies between 20 and 55 Hz. Whilst the results were consistent with adsorption affecting sound propagation, other phenomena cannot be ruled out. Measurements of sorption isotherms showed that additional energy losses can be caused by water vapor condensing onto and then evaporating from the surface of the material. However, the excess absorption measured for low frequency sound waves is primarily caused by decreases in surface reactance rather than changes in surface resistance. PMID:22779473

Bechwati, F; Avis, M R; Bull, D J; Cox, T J; Hargreaves, J A; Moser, D; Ross, D K; Umnova, O; Venegas, R

2012-07-01

391

Single crystalline mesoporous silicon nanowires  

SciTech Connect

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. These porous nanowires also retain the crystallographic orientation of the wafer from which they are etched. Electron microscopy and diffraction confirm their single-crystallinity and reveal the silicon surrounding the pores is as thin as several nanometers. Confocal fluorescence microscopy showed that the photoluminescence (PL) of these arrays emanate from the nanowires themselves, and their PL spectrum suggests that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices.

Hochbaum, A.I.; Gargas, Daniel; Jeong Hwang, Yun; Yang, Peidong

2009-08-04

392

Sorption of elemental mercury by activated carbons  

SciTech Connect

The paper gives results of a study of the mechanisms and rate of elemental mercury (Hg) capture by activated carbons, using a bench-scale apparatus. Three types of activated carbons, two thermally activated (PC-100 and FGD) and one impregnated with elemental sulfur (S) (HGR), were used to study the effects of surface area (approximately 550-1000 sq m/g), sorption temperature (23-140 C), and elemental Hg concentration (30 and 60 ppb of elemental Hg in nitrogen). Investigations revealed that sorption occurs in active sites in PC-100 and FGD which are either depleted or deactivated at 140 C. Desorption studies for PC-100 and HGR revealed the sorption mechanism to be a combination of physisorption and chemisorption at 23 C, whereas chemisorptionis the primary route at 140 C.

Krishnan, S.V.; Gullett, B.K.; Jozewicz, W.

1994-01-01

393

Hydrogen adsorption on modified activated carbon  

Microsoft Academic Search

The aim of this work is to investigate hydrogen adsorption on prepared super activated carbon (AC). Litchi trunk was activated by potassium hydroxide under N2 or CO2 atmosphere. Nanoparticles of palladium were impregnated in the prepared-AC. Hydrogen adsorption was accurately measured by a volumetric adsorption apparatus at 77, 87, 90 and 303K, up to 5MPa. Experimental results revealed that specific

Chen-Chia Huang; Hsiu-Mei Chen; Chien-Hung Chen

2010-01-01

394

Pilot-scale demonstration of the OSCAR process for high-temperature multipollutant control of coal combustion flue gas, using carbonated fly ash and mesoporous calcium carbonate  

SciTech Connect

A pilot-scale study of the Ohio State Carbonation Ash Reactivation (OSCAR) process was performed to demonstrate the reactivity of two novel calcium-based sorbents toward sulfur and trace heavy metal (arsenic, selenium, and mercury) capture in the furnace sorbent injection (FSI) mode on a 0.365 m{sup 3}/s slipstream of a bituminous coal-fired stoker boiler. The sorbents were synthesized by bubbling CO{sub 2} to precipitate calcium carbonate (a) from the unreacted calcium present in the lime spray dryer ash and (b) from calcium hydroxide slurry that contained a negatively charged dispersant. The heterogeneous reaction between these sorbents and SO{sub 2} gas occurred under entrained flow conditions by injecting fine sorbent powders into the flue gas slipstream. The reacted sorbents were captured either in a hot cyclone (about 650{sup o}C) or in the relatively cooler downstream baghouse (about 230{sup o}C). The baghouse samples indicated about 90% toward sulfation and captured arsenic, selenium and mercury to 800 ppmw, 175 ppmw and 3.6 ppmw, respectively.

Gupta, H.; Thomas, T.J.; Park, A.H.A.; Iyer, M.V.; Gupta, P.; Agnihotri, R.; Jadhav, R.A.; Walker, H.W.; Weavers, L.K.; Butalia, T.; Fan, L.S. [Ohio State University, Columbus, OH (United States)

2007-07-15

395

Supercapacitor Electrodes from Activated Carbon Monoliths and Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Binderless monoliths of supercapacitor electrodes were prepared by the carbonization (N2) and activation (CO2) of green monoliths (GMs). GMs were made from mixtures of self-adhesive carbon grains (SACG) of fibers from oil palm empty fruit bunches and a combination of 5 & 6% KOH and 0, 5 & 6% carbon nanotubes (CNTs) by weight. The electrodes from GMs containing CNTs were found to have lower specific BET surface area (SBET). The electrochemical behavior of the supercapacitor fabricated using the prepared electrodes were investigated by electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD). In general an addition of CNTs into the GMs reduces the equivalent series resistance (ESR) value of the cells. A cell fabricated using electrodes from GM with 5% CNT and 5% KOH was found to have the largest reduction of ESR value than that from the others GMs containing CNT. The cell has steeper Warburg's slope than that from its respective non-CNT GM, which reflect the smaller resistance for electrolyte ions to move into pores of electrodes despite these electrodes having largest reduction in specific BET surface area. The cell also has the smallest reduction of specific capacitance (Csp) and maintains the specific power range despite a reduction in the specific energy range due to the CNT addition.

Dolah, B. N. M.; Othman, M. A. R.; Deraman, M.; Basri, N. H.; Farma, R.; Talib, I. A.; Ishak, M. M.

2013-04-01

396

Silver-containing mesoporous bioactive glass with improved antibacterial properties.  

PubMed

The aim of the present work is the study of the bacteriostatic/bactericidal effect of a silver-containing mesoporous bioactive glass obtained by evaporation-induced self-assembly and successive thermal stabilization. Samples of the manufactured mesophase were characterized by means of transmission electron microscopy and N2 adsorption/desorption at 77 K, revealing structural and textural properties similar to SBA-15 mesoporous silica. Glass samples used for bioactivity experiments were put in contact with a standardized, commercially available cell culture medium instead of lab-produced simulated body fluid, and were then characterized by means of X-ray diffraction, field emission scanning electron microscopy and Fourier transform infrared spectroscopy. All these analyses confirmed the development of a hydroxyl carbonate apatite layer on glass particles. Moreover, the investigated mesostructure showed a very good antibacterial effect against S. aureus strain, with a strong evidence of bactericidal activity already registered at 0.5 mg/mL of glass concentration. A hypothesis about the mechanism by which Ag affects the bacterial viability, based on the intermediate formation of crystalline AgCl, was also taken into account. With respect to what already reported in the literature, these findings claim a deeper insight into the possible use of silver-containing bioactive glasses as multifunctional ceramic coatings for orthopedic devices. PMID:23712538

Gargiulo, Nicola; Cusano, Angela Maria; Causa, Filippo; Caputo, Domenico; Netti, Paolo Antonio

2013-05-28

397

Preparation and photocatalytic activity of magnetic samarium-doped mesoporous titanium dioxide at the decomposition of methylene blue under visible light  

NASA Astrophysics Data System (ADS)

Preparation of samarium-doped mesoporous titanium dioxide (Sm/MTiO2) coated magnetite (Fe3O4) photocatalysts (Sm/MTiO2/Fe3O4) and their activities under visible light were reported. The catalysts with Sm/MTiO2 shell and a Fe3O4 core were prepared by coating photoactive Sm/MTiO2 onto a magnetic Fe3O4 core through the hydrolysis of tetrabutyltitanate (Ti(OBu)4, TBT) with precursors of Sm(NO3)3 and TBT in the presence of Fe3O4 nanoparticles. The morphological, structural and optical properties of the prepared samples were characterized by BET surface area, transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy. The effect of Sm ion content on the photocatalytic activity was studied. The photocatalytic activities of obtained photocatalysts under visible light were estimated by measuring the decomposition rate of methylene blue (MB, 50 mg/L) in an aqueous solution. The results showed that the prepared photocatalyst was activated by visible light and used as effective catalyst in photooxidation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, Sm/MTiO2 was tightly bound to Fe3O4 and could be easily recovered from the medium by a simple magnetic process. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.

Shi, Zhongliang; Lai, Hong; Yao, Shuhua

2012-08-01

398

Ordered mesoporous polymers and polymer-silica anocomposites  

Microsoft Academic Search

A family of highly ordered mesoporous polymers and carbon frameworks, including p6m, Ia3d, Im3m Fm3m, and Fd3m mesostructures, has been prepared by the organic-organic assembly of triblock copolymers PEO-PPO-PEO, reverse copolymer PPO-PEO-PPO and PEO-PS with resols via solvent evaporation-induced self-assembly (EISA) strategy. By using pre-hydrolyzed TEOS as an inorganic co-precursor, highly ordered mesoporous polymer-silica and carbon-silica nanocomposites with interpenetrating networks

Ruili Liu; Yan Meng; Dong Gu; Bo Tu; Dongyuan Zhao

2007-01-01

399

Catalytic wet air oxidation of phenol with modified activated carbons and Fe\\/activated carbon catalysts  

Microsoft Academic Search

A commercial activated carbon was modified by different oxidative treatments to introduce different oxygen surface groups. A gentle oxidation in gas phase with a poor oxygen stream and a more severe oxidation in liquid phase with a HNO3 solution were used. The resulting activated carbons and the corresponding Fe-impregnated (2.5% Fe) ones were tested for the wet air oxidation of

A. Quintanilla; J. A. Casas; J. J. Rodríguez

2007-01-01

400

N-doped SiO2/TiO2 mesoporous nanoparticles with enhanced photocatalytic activity under visible-light irradiation.  

PubMed

Mesoporous nanocrystalline N-doped SiO2/TiO2 visible-light photocatalysts were prepared by treating SiO2/TiO2 xerogels in a flow of nitrogen gas bubbled through concentrated ammonia solution. Structural characterization and performance analysis results revealed that the addition of SiO2 remarkably altered the phase composition, specific surface area, microstructure, as well as the photocatalytic activity of N-doped TiO2. The presence of SiO2 in N-doped TiO2 particles suppressed the formation of rutile phase and the crystal growth of N-doped TiO2 particles during thermal calcinations. When weight ratio of SiO2/TiO2 was in 0.05-0.20, the N-doped SiO2/TiO2 exhibited higher photocatalytic activity than the N-doped TiO2, and optimum ratio was found to be 0.05. The enhanced photocatalytic activity could be attributed to the higher specific area, larger pore volume, and more surface hydroxyl groups in the catalyst. PMID:18423518

Hou, Y D; Wang, X C; Wu, L; Chen, X F; Ding, Z X; Wang, X X; Fu, X Z

2008-04-18

401

In situ incorporation of nickel nanoparticles into the mesopores of MCM-41 by manipulation of solvent–solute interaction and its activity toward adsorptive desulfurization of gas oil  

Microsoft Academic Search

In this contribution, different amounts of nickel were incorporated into the mesopores of MCM-41 via an in situ approach. A hydrophobic nickel precursor was incorporated into the nanochannels of mesoporous silica by manipulation of solvent–solute interaction. The synthesized material was characterized using X-ray diffraction, nitrogen physisorption, temperature programmed reduction, and transmission electron microscopy. The results implicate the formation of MCM-41

Abdolraouf Samadi-Maybodi; Mohammad Teymouri; Amir Vahid; Aliakbar Miranbeigi

2011-01-01

402

One-pot construction of functional mesoporous silica nanoparticles for the tumor-acidity-activated synergistic chemotherapy of glioblastoma.  

PubMed

Mesoporous silica nanoparticles (MSNs) have proved to be an effective carrier for controlled drug release and can be functionalized easily for use as stimuli-responsive vehicles. Here, a novel intelligent drug-delivery system (DDS), camptothecin (CPT)-loaded and doxorubicin (DOX)-conjugated MSN (CPT@MSN-hyd-DOX), is reported via a facile one-pot preparation for use in synergistic chemotherapy of glioblastoma. DOX was conjugated to MSNs via acid-labile hydrazone bonds, and CPT was loaded in the pores of the MSNs. At pH 6.5 (analogous to the pH in tumor tissues), a fast DOX release was observed that was attributed to the hydrolysis of the hydrazone bonds. In addition, a further burst release of DOX was found at pH 5.0 (analogous to the pH in lyso/endosomes of tumor cells), leading to a strong synergistic effect. In all, CPT and DOX could be delivered simultaneously into tumor cells, and this intelligent DDS has great potential for tumor-trigged drug release for use in the synergistic chemotherapy of tumors. PMID:23869943

Li, Ze-Yong; Liu, Yun; Wang, Xiao-Qiang; Liu, Li-Han; Hu, Jing-Jing; Luo, Guo-Feng; Chen, Wei-Hai; Rong, Lei; Zhang, Xian-Zheng

2013-08-02

403

Metal ion adsorption using polyamine-functionalized mesoporous materials prepared from bromopropyl-functionalized mesoporous silica.  

PubMed

Mesoporous silicas carrying di-, tri-, or penta-amine functional groups were prepared by prior functionalization of a mesoporous silica with bromopropyl-functional groups followed by nucleophilic displacement of the bromine atoms by ethylenediamine, diethylenetriamine, or tetraethylenepentamine, respectively. A synthetic method was developed that gave a starting material with very high surface coverage by the 3-brompropyl groups. Batch tests were conducted to investigate the capabilities of the prepared adsorbents for the removal of copper, zinc, and cadmium from aqueous solutions. The metal adsorption capacities for these metals were determined as a function of the polyamine group used and the total nitrogen content. The tendency to chemisorb divalent metal ions was found to follow the order: Cu(2+)>Zn(2+)>Cd(2+). It was found that the ethylenediamine derivative unexpectedly exhibited the highest capacities. The metal sorption by the ethylenediamine functionalized silica was found to follow first order kinetics with rate constants for Cu(2+), Zn(2+) and Cd(2+) uptake of 0.028, 0.019, and 0.014 min(-1), respectively. The substituted mesoporous silicas showed high resistance to leaching of the grafted polyamine groups. Copper ions that were adsorbed at the surface of the mesoporous silicas can be recovered by washing with an aqueous solution of 1.0 M HNO(3). The activities of the recovered mesoporous silicas were between 80 and 90% of the original materials. PMID:20663609

Alothman, Zeid A; Apblett, Allen W

2010-06-25

404

Silica-based mesoporous nanoparticles for controlled drug delivery  

PubMed Central

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

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

2013-01-01

405

Interactions of xanthines with activated carbon  

NASA Astrophysics Data System (ADS)

Because of their pharmaceutical and industrial applications, we have studied the adsorption of xanthine derivates (caffeine and theophylline) by activated carbon. To this end, we examined kinetic, equilibrium and thermodynamic aspects of the process. This paper reports the kinetics results. The experimental results indicate that the process was first order in C and the overall process was assumed to involve a single, reversible adsorption desorption process obeying a kinetic law postulated by us.

Navarrete Casas, R.; García Rodriguez, A.; Rey Bueno, F.; Espínola Lara, A.; Valenzuela Calahorro, C.; Navarrete Guijosa, A.

2006-06-01

406

The production of chemically-activated carbon  

Microsoft Academic Search

In an attempt to optimise the microporosity in an activated carbon, controlled heating of sucrose chars and other precursor materials was carried out in an inert environment with an excess of potassium or sodium hydroxide. Initially, the precursor materials were subjected to a regulated temperature–time profile to elevated temperatures (400–900°C) and subsequently cooled. The products were then exposed either to

M. J. B Evans; E Halliop; J. A. F MacDonald

1999-01-01

407

Palladium catalysts on activated carbon supports  

Microsoft Academic Search

A number of activated carbons produced from peat, coconut shell, and by pyrolysis of hydrocarbons have been subjected to treatment with oxygen, chlorine, hydrogen or ammonia at elevated temperatures to get a representative series of catalyst supports differing in porous structure and surface chemistry (characterized by nitrogen adsorption and selective titrations). Palladium was deposited from anionic (H2PdCl4), neutral (Pd(OAc)2, in

M. Gurrath; T. Kuretzky; H. P. Boehm; L. B. Okhlopkova; A. S. Lisitsyn; V. A. Likholobov

2000-01-01

408

Biomorphic activated porous carbons with complex microstructures from lignocellulosic residues  

Microsoft Academic Search

Transformation of coir fibers, coir pith and coconut shell endocarp microstructures is described for the formation of activated carbons. The carbonization\\/activation process was carried out using ZnCl2 as activating agent at 800°C under CO2 atmosphere. The carbonization\\/activation process was evaluated by TGA\\/DTG measurements which evidenced an increase in the initial decomposition temperature along with increase in the carbon amount as

Jeremias S. Macedo; Larissa Otubo; Odair Pastor Ferreira; Iara de Fátima Gimenez; Italo Odone Mazali; Ledjane Silva Barreto

2008-01-01

409

Elimination of carcinogens (excluding haloforms) from water by active carbon  

Microsoft Academic Search

Elimination of carcinogens (excluding haloforms) from water by active carbon was studied in the laboratory. Ten activated carbons were tested for their ability to adsorb eight different polycyclic aromatic hydrocarbons (PAH). The PAH were introduced in acetone solution to synthetic sewage water. Activated carbon concentration was 1 g\\/l. and contact time was 30 min at 15° with a 500 rpm

Borneff

1978-01-01

410

Capped Mesoporous Silicates.  

National Technical Information Service (NTIS)

The invention provides an article comprising, a mesoporous silicate matrix, such as a particle, having one or more pores; and one or more releasable caps obstructing one or more of the pores. The articles are useful as delivery vehicles for encapsulated a...

C. Y. Lai D. M. Jeftinija S. Jeftinija V. S. Y. Lin

2004-01-01

411

Molecularly imprinted mesoporous organosilica.  

PubMed

We have prepared molecularly imprinted mesoporous organosilica (MIMO) using a semicovalent imprinting technique. A thermally reversible covalent bond was used to link a bisphenol A (BPA) imprint molecule to a functional alkoxysilane monomer at two points to generate a covalently bound imprint precursor. This precursor was incorporated into a cross-linked periodic mesoporous silica matrix via a typical acid-catalyzed, triblock copolymer-templated, sol-gel synthesis. Evidence of imprint sites buried in the pore walls was found through careful characterization of the imprinted material and its comparison to similarly prepared non-imprinted mesoporous organosilica (NIMO) and pure periodic mesoporous silica (PMS). After thermal treatment, the imprinted material (MIMO-ir) removed more than 90% of appropriately sized bisphenol species from water, yet showed significantly lower binding for both smaller and larger molecules containing phenol moieties. Identically treated NIMO-ir showed much poorer retention behavior than MIMO-ir for the same bisphenol species and behaved only slightly better than PMS-ir. PMID:21323322

Lofgreen, Jennifer E; Moudrakovski, Igor L; Ozin, Geoffrey A

2011-02-16

412

Mesoporous aluminum phosphite  

SciTech Connect

High surface area pure mesoporous aluminum-phosphorus oxide-based derivatives have been synthesized through an S{sup +}I{sup -} surfactant-assisted cooperative mechanism by means of a one-pot preparative procedure from aqueous solution and starting from aluminum atrane complexes and phosphoric and/or phosphorous acids. A soft chemical extraction procedure allows opening the pore system of the parent as-prepared materials by exchanging the surfactant without mesostructure collapse. The nature of the pore wall can be modulated from mesoporous aluminum phosphate (ALPO) up to total incorporation of phosphite entities (mesoporous aluminum phosphite), which results in a gradual evolution of the acidic properties of the final materials. While phosphate groups in ALPO act as network building blocks (bridging Al atoms), the phosphite entities become basically attached to the pore surface, what gives practically empty channels. The mesoporous nature of the final materials is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and N{sub 2} adsorption-desorption isotherms. The materials present regular unimodal pore systems whose order decreases as the phosphite content increases. NMR spectroscopic results confirm the incorporation of oxo-phosphorus entities to the framework of these materials and also provide us useful information concerning the mechanism through which they are formed. - Abstract: TEM image of the mesoporous aluminum phosphite showing the hexagonal disordered pore array that is generated by using surfactant micelles as template. Also a scheme emphasizing the presence of an alumina-rich core and an ALPO-like pore surface is presented.

El Haskouri, Jamal, E-mail: haskouri@uv.e [Institut de Ciencia dels Materials de la Universitat de Valencia (ICMUV), P. O. Box 22085, 46071 Valencia (Spain); Perez-Cabero, Monica; Guillem, Carmen; Latorre, Julio; Beltran, Aurelio; Beltran, Daniel [Institut de Ciencia dels Materials de la Universitat de Valencia (ICMUV), P. O. Box 22085, 46071 Valencia (Spain); Amoros, Pedro, E-mail: pedro.amoros@uv.e [Institut de Ciencia dels Materials de la Universitat de Valencia (ICMUV), P. O. Box 22085, 46071 Valencia (Spain)

2009-08-15

413

Self-templating synthesis of hollow mesoporous silica and their applications in catalysis and drug delivery.  

PubMed

Hollow mesoporous silica materials have been intensively pursued because of their unique properties for various applications. Yolk/shell structured hollow mesoporous silica with functional cores inside their hollow interior can further broaden the applications of hollow mesoporous silica. The self-templating strategy has been developed as one of the most important strategies to effectively fabricate hollow mesoporous silicas and their yolk/shell counterparts. In this feature article, we provide an overview of advances in the self-templating synthesis of hollow mesoporous silica based on the following three strategies: surface-protected etching, structural difference-based selective etching, and cationic surfactant assisted self-templating. We then discuss some important applications of these self-templating strategy-derived hollow mesoporous silicas, such as nanoreactors for confined catalysis and multifunctional platforms for combined therapy. Finally, some perspectives for the future development of this active research field are provided. PMID:23400270

Fang, Xiaoliang; Zhao, Xiaojing; Fang, Weijun; Chen, Cheng; Zheng, Nanfeng

2013-03-21

414

Self-templating synthesis of hollow mesoporous silica and their applications in catalysis and drug delivery  

NASA Astrophysics Data System (ADS)

Hollow mesoporous silica materials have been intensively pursued because of their unique properties for various applications. Yolk/shell structured hollow mesoporous silica with functional cores inside their hollow interior can further broaden the applications of hollow mesoporous silica. The self-templating strategy has been developed as one of the most important strategies to effectively fabricate hollow mesoporous silicas and their yolk/shell counterparts. In this feature article, we provide an overview of advances in the self-templating synthesis of hollow mesoporous silica based on the following three strategies: surface-protected etching, structural difference-based selective etching, and cationic surfactant assisted self-templating. We then discuss some important applications of these self-templating strategy-derived hollow mesoporous silicas, such as nanoreactors for confined catalysis and multifunctional platforms for combined therapy. Finally, some perspectives for the future development of this active research field are provided.

Fang, Xiaoliang; Zhao, Xiaojing; Fang, Weijun; Chen, Cheng; Zheng, Nanfeng

2013-02-01

415

Preparing and characterizing the active carbon produced by steam and carbon dioxide as a heavy oil hydrocracking catalyst support  

Microsoft Academic Search

Active carbon was prepared from Yallourn brown coal char using steam and carbon dioxide activation in a laboratory rotary kiln. The activation rate with steam was faster than that with carbon dioxide. The pore structure of the active carbons was characterized using the nitrogen isotherms at 77K. The pore volume and specific surface area of the active carbon increased with

Hidetsugu Fukuyama; Satoshi Terai

2008-01-01

416

Synthesis and characterization of mesoporous zirconia and aluminated mesoporous zirconia  

NASA Astrophysics Data System (ADS)

Synthesis of mesoporous zirconia has been performed by slowly hydrolyzing zirconium propoxide in the presence of anionic surfactants: namely, dodecyl phosphate or sulfate (P12 and Sf12) and hexadecyl sulfonate (So16) The zirconia. outgassed at 140--150°C has T-plot surface areas higher than 400 M2/g. This outgassing does not remove the surfactant. After calcination in air at 500°C and combustion of the surfactant, the mesoporous volume is reduced by a factor of about 2, whereas the pore wall material crystallizes in the tetragonal phase. The high-resolution electron microscopic study reveals the presence of a disorganized network of polygonal pores structure. It is suggested that the chemistry of the hydrolysis solution is instrumental in determining the pore structure. A schematic model in which the surfactant is a scaffold component is suggested in order to explain these results and the fixation of PO4, or SO4 in the walls may help to preserve the porous structure. It is very different from the templating mechanism. From the density obtained from phase transition temperature, and from the mesoporous volume (N2 adsorption), the thickness of the wall can be calculated as well as the pseudo-length of the pores. From the thickness, the T-plot area can be recalculated and agrees well with the measured T-plot surface area for the sample calcined at 500°C. Around 900°C, the walls become thicker and crystallizes into monoclinic zirconia without pore structure. In order to try to modify, the acidity of the mesoporous sulfated and oxo-phosphated zirconia, they were doped with aluminum. The sulfated zirconia only has a coating layer of amorphous alumina, while the phosphated zirconia has aluminum in the lattice and the alumina coat. A maximum ratio of Al/Zr ˜ 0.04 can be reached in the lattice. The introduction of aluminum into the lattice prevents the crystallization of the oxo-phosphate at 900°C, and helps to preserve the surface area and porosity of the sulfated zirconia above 500°C. However the acidity was not modified by doping. The comparison of the effects of adsorbing water or ammonia on the infrared bands between 1400 and 1000 cm-1 suggests that, besides structural Lewis sites on the surface of ZrO2, the strong Lewis sites are made from chemisorbed SO3. Upon adsorption of water, SO3 is converted, probably, into HSO4 which may act as strong Bronsted sites. At moderate surface hydration, both SO 3 and HSO4, may coexist. The catalytic activity in the isomerization of isobutane is a function of the overall nominal surface density of SO 4. The acid sites on the surface of phosphated mesoporous zirconia are attributable to surface P-OH groups working, as weak Bronsted sites.

Zhao, Elizabeth Sun

417

Phosphotungstic acid anchored to amino-functionalized core-shell magnetic mesoporous silica microspheres: a magnetically recoverable nanocomposite with enhanced photocatalytic activity.  

PubMed

H(3)PW(12)O(40) was successfully anchored to the surface of amino-functionalized Fe(3)O(4)@SiO(2)@meso-SiO(2) microspheres by means of chemical bonding to aminosilane groups, aiming to remove unwanted organic compounds from aqueous media. The resultant multifunctional microspheres were thoroughly characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, infrared spectroscopy, inductively coupled plasma, and N(2) adsorption-desorption. The as-prepared microspheres possess unique properties including high magnetization (46.8 emu g(-1)), large BET surface area (135 m(2) g(-1)), and highly open mesopores (~5.0 nm), and H(3)PW(12)O(40) loading is calculated to be ~16.8%; and as a result, the as-prepared microspheres exhibit enhanced performance in degrading dyes under UV irradiation compared with pure H(3)PW(12)O(40). Additionally, the photocatalyst can be easily recycled using an external magnetic field without losing the photocatalytic activity. PMID:23083769

Zhao, Liang; Chi, Yue; Yuan, Qing; Li, Nan; Yan, Wenfu; Li, Xiaotian

2012-09-17

418

Investigation kinetics mechanisms of adsorption malachite green onto activated carbon  

Microsoft Academic Search

Lignite was used to prepare activated carbon (T3K618) by chemical activation with KOH. Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by t-plot based on N2 adsorption isotherm. BET surface area of activated carbon is determined as 1000m2\\/g. Adsorption capacity of malachite green (MG) onto T3K618 activated

Y. Önal; C. Akmil-Ba?ar; Ç. Sar?c?-Özdemir

2007-01-01

419

ENTRAINED-FLOW ADSORPTION OF MERCURY USING ACTIVATED CARBON  

EPA Science Inventory

Bench-scale experiments were conducted in a flow reactor to simulate entrained-flow capture of elemental mercury (Hg) by activated carbon. Adsorption of Hg by several commercial activated carbons was examined at different carbon-to-mercury (C:Hg) ratios (by weight) (600:1 - 29000...

420

The regeneration of polluted activated carbon by radiation techniques  

NASA Astrophysics Data System (ADS)

In this paper, the regeneration of used activated carbon from monosodium glutamate factory was experimented using radiation and acid-alkali chemical cleaning method. Results showed that the activated carbon saturated with pollutants can be wash away easily by flushing with chemical solution prior irradiation. DSC was used to monitor the change of carbon adsorption

Minghong, W.; Borong, B.; Ruimin, Z.; Jinliang, Z.; Longxin, H.

1998-10-01

421

Gold recovery by microwave augmented ashing of waste activated carbon  

Microsoft Academic Search

Gold ore processing plants that utilize carbon adsorption technologies generate a waste activated carbon, which contains very high gold values, and the recovery of this gold represents a significant source of extra revenue. In this research, microwave energy was utilized to combust the waste activated carbon and the resulting ash was treated by conventional cyanide leaching to recover the gold.

R. K. Amankwah; C. A. P