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1

Activated carbon filaments with mainly mesopores  

SciTech Connect

Activated carbon filaments of diameter {approximately} 0.1 {micro}m, mean pore size (BJH) 65 {angstrom}, specific surface area 1,540 m{sup 2}/g and burn-off 64% (yield 36%) were obtained by activating carbon filaments of diameter {approximately} 0.1 {micro}m in CO{sub 2} + N{sub 2} (1:1) at 970 C for100 min. Prior to this activation, the filaments were surface oxidized by exposure to ozone (0.3 vol.% in air) at 150 C for 3 min. Other than being used as adsorbents for purification and chemical processing, activated carbon materials are used as catalytic materials, battery electrode materials and biomedical engineering materials.

Lu, W.; Chung, D.D.L. [State Univ. of New York, Buffalo, NY (United States). Composite Materials Research Lab.

1996-12-31

2

Mesoporous carbon materials  

DOEpatents

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

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

2014-09-09

3

Immobilization of high catalytic acid protease on functionalized mesoporous activated carbon particles  

Microsoft Academic Search

The functionalized mesoporous activated carbon (FMAC) was used as support material for immobilization of acid protease (AP). Immobilization of acid protease on functionalized mesoporous activated carbon (AP–FMAC) performs as a suitable enzyme carrier. Under optimized condition pH (6.0) acid protease 150mgg?1 FMAC has been adsorbed. The optimum temperature for both free and immobilized AP activities was 50°C. After incubation at

A. Ganesh Kumar; S. Swarnalatha; P. Kamatchi; G. Sekaran

2009-01-01

4

[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

5

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

6

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

7

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

8

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

PubMed Central

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

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

2014-01-01

9

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

10

Sulfur-Functionalized Mesoporous Carbon  

SciTech Connect

A simple, direct synthesis of mesoporous carbons containing heteroaromatic functionality is described. Superior performance of these mesoporous heterocarbons as heavy metal sorbent material is demonstrated. These materials are shown to be stable towards elevated temperatures and extreme pHs.

Shin, Yongsoon; Fryxell, Glen E.; Um, Wooyong; Parker, Kent E.; Mattigod, Shas V.; Skaggs, Richard

2007-10-15

11

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

12

Ammonia-activated mesoporous carbon membranes for gas separations  

Microsoft Academic Search

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.

Shannon Mark Mahurin; Je Seung Lee; Xiqing Wang; Sheng Dai

2011-01-01

13

Reversible replication between ordered mesoporous silica and mesoporous carbon  

E-print Network

, catalyst supports and materials for advanced electronics applications. Among the mesoporous carbon of mesoporous silica SBA-15, indicating reversible replication between carbon and inorganic materials. Ordered mesoporous materials such as MCM-41, MCM-48, SBA-15, etc.1,2 have attracted much attention due to their large

Kim, Ji Man

14

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. 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

2013-01-01

15

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

16

Immobilization of polyphenol oxidase onto mesoporous activated carbons -- isotherm and kinetic studies.  

PubMed

Investigations were carried out in batch modes for studying the immobilization behavior of polyphenol oxidase (PPO) on two different mesoporous activated carbon matrices, MAC400 and MAC200. The PPO was immobilized onto MAC400 and MAC200 at various enzyme activities 5 x 10(4), 10 x 10(4), 20 x 10(4), 30 x 10(4)Ul(-1), at pH 5-8, and at temperature ranging from 10 to 40 degrees C. The intensity of immobilization of PPO increased with increase in temperature and initial activities, while it decreased with increase in pH. Immobilization onto MAC400 followed the Langmuir model while Langmuir and Freundlich models could fit MAC200 data. Non-linear pseudo first order, pseudo second order and intraparticle diffusion models were evaluated to understand the mechanism of immobilization. The free and immobilized enzyme kinetic parameters (K(m) and V(max)) were determined by Michaelis-Menten enzyme kinetics. The K(m) values for free enzyme, PPO immobilized in MAC400 and in MAC200 were 0.49, 0.41 and 0.65 mM, respectively. The immobilization of PPO in carbon matrices was confirmed using FT-IR spectroscopy and scanning electron microscopy. PMID:17544053

Kennedy, L John; Selvi, P K; Padmanabhan, Aruna; Hema, K N; Sekaran, G

2007-09-01

17

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

18

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

2011-02-15

19

The enhanced electrocatalytic activity of okara-derived N-doped mesoporous carbon for oxygen reduction reaction  

NASA Astrophysics Data System (ADS)

Nitrogen-doped carbon (N-C) catalysts can potentially offer high ORR (oxygen reduction reaction) electrocatalytic activity comparable to Pt/C catalysts. Here, we establish a correlation between N-species (pyridinic-N and graphitic-N) with high ORR activity and a key role for Fe in their preparation. N-C catalysts are prepared from okara (a cheap, nitrogen-rich, biomass precursor) using a facile synthesis method with inclusion of FeCl3 at different steps of synthesis. Mesoporous N-C catalyst is produced that had ORR activity comparable to that of commercial Pt/C catalyst. High ORR-activity N-C results from the presence of FeCl3 at a specific step during synthesis. Detailed investigation by XPS reveals that increased levels of pyridinic-N and graphitic-N arose from pyridinic-N-oxide conversion in the presence of Fe. We conclude that transforming inert N species to active N species underlies the increase in active catalytic sites on the carbon surface and offers a means to improve N-C catalyst performance.

Wang, Rongfang; Wang, Hui; Zhou, Tianbao; Key, Julian; Ma, Yanjiao; Zhang, Zheng; Wang, Qizhao; Ji, Shan

2015-01-01

20

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

PubMed

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

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

2015-01-01

21

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

PubMed Central

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

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

2015-01-01

22

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

23

Adsorption characteristics of arsenic from micro-polluted water by an innovative coal-based mesoporous activated carbon.  

PubMed

An innovative coal-based mesoporous activated carbon (NCPAC) was prepared by re-agglomeration, oxidation and two-step activation using coal-blending as precursor. Adsorption capacities of As(III) and As(V) ions (<0.5mg/L) onto NCPAC as a function of pH, adsorbent dose, initial arsenic concentrations, contact time, and adsorption isotherms at 7°C was investigated. The innovative methods promoted total pore volume (1.087cm(3)/g), mesoporosity (64.31%), iodine numbers (1104mg/g), methylene blue (251.8mg/g) and ash contents (15.26%). The adsorption capacities of NCPAC for As(III) and As(V) were found to be strongly dependent on pH and contact time. The optimal pH value was 6. The equilibrium time was 60min for adsorption of As(III) and As(V) by NCPAC. The Langmuir model fitted the experimental data well for both As(III) (R(2)=0.9980) and As(V) (R(2)=0.9988). Maximum adsorption capacities of As(III) and As(V) (C0=0.50mg/L) by NCPAC were 1.491 and 1.760mg/g, respectively. PMID:24631151

Li, Wei-Guang; Gong, Xu-Jin; Wang, Ke; Zhang, Xin-Ran; Fan, Wen-Biao

2014-08-01

24

Mesoporous carbon nanomaterials as environmental adsorbents.  

PubMed

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

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

2014-02-01

25

Three-Dimensional Coherent Titania-Mesoporous Carbon Nanocomposite and Its Lithium-Ion Storage Properties  

E-print Network

, open mesoporosity, and nanosized active material, coherent mesoporous TiO2/C and Li4Ti5O12/C power applications, advanced materials with better safety and high rate capability are critical for nextThree-Dimensional Coherent Titania-Mesoporous Carbon Nanocomposite and Its Lithium-Ion Storage

Cao, Guozhong

26

Hydrogen Storage on Metal-Doped Ordered Mesoporous Carbons  

E-print Network

Materials Advanced Materials #12;Group Members Ph.D.: P. Patil, D. Saha; P. Teli; K. Pingali; V. UpadhyayulaHydrogen Storage on Metal-Doped Ordered Mesoporous Carbons Shuguang Deng New Mexico State in Ordered Mesoporous Carbon Synthesized by Soft-Template Approach" J. Porous Media, 13, 39-50 (2010). 9

Johnson, Eric E.

27

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

PubMed

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

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

2014-05-21

28

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

29

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

30

Mesoporous Carbon Materials: Synthesis and Modification  

SciTech Connect

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 extremely high surface areas and ordered mesostructures, with potential applications as catalysts, separation media, and advanced electronic materials in many scientific disciplines. Current syntheses can be categorized as either hard-template or soft-template methods. Both are examined in this Review along with procedures for surface functionalization of the carbon materials obtained.

Liang, Chengdu [ORNL; Li, Zuojiang [ORNL; Dai, Sheng [ORNL

2008-01-01

31

Mesoporous Carbon Materials: Synthesis and Modificaiton  

SciTech Connect

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 extremely high surface areas and ordered mesostructures, with potential applications as catalysts, separation media, and advanced electronic materials in many scientific disciplines. Current syntheses can be categorized as either hard-template or soft-template methods. Both are examined in this Review along with procedures for surface functionalization of the carbon materials obtained.

Dai, Sheng [ORNL; Liang, Chengdu [ORNL; Li, Zuojiang [ORNL

2008-01-01

32

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

33

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

PubMed

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

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

2014-11-21

34

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

NASA Astrophysics Data System (ADS)

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

Kado, Yuya; Soneda, Yasushi; Yoshizawa, Noriko

2015-02-01

35

Catalyst-free synthesis of transparent, mesoporous diamond monoliths from periodic mesoporous carbon CMK-8  

PubMed Central

We report on the synthesis of optically transparent, mesoporous, monolithic diamond from periodic mesoporous carbon CMK-8 at a pressure of 21 GPa. The phase transformation is already complete at a mild synthesis temperature of 1,300?°C without the need of a catalyst. Surprisingly, the diamond is obtained as a mesoporous material despite the extreme pressure. X-ray diffraction, SEM, transmission electron microscopy, selected area electron diffraction, high-resolution transmission electron microscopy, and Z-contrast experiments suggest that the mesoporous diamond is composed of interconnected diamond nanocrystals having diameters around 5–10 nm. The Brunauer Emmett Teller surface area was determined to be 33 m2 g-1 according Kr sorption data. The mesostructure is diminished yet still detectable when the diamond is produced from CMK-8 at 1,600?°C and 21 GPa. The temperature dependence of the porosity indicates that the mesoporous diamond exists metastable and withstands transformation into a dense form at a significant rate due to its high kinetic inertness at the mild synthesis temperature. The findings point toward ultrahard porous materials with potential as mechanically highly stable membranes. PMID:20643963

Zhang, Li; Mohanty, Paritosh; Coombs, Neil; Fei, Yingwei; Mao, Ho-Kwang; Landskron, Kai

2010-01-01

36

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

37

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

38

Synthesis of Ordered Mesoporous Phenanthrenequinone-Carbon via ?-? Interaction-Dependent Vapor Pressure for Rechargeable Batteries  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

39

Synthesis of Ordered Mesoporous Phenanthrenequinone-Carbon via ?-? Interaction-Dependent Vapor Pressure for Rechargeable Batteries  

PubMed Central

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

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

2014-01-01

40

Dealloying of Mesoporous PtCu Alloy Film for the Synthesis of Mesoporous Pt Films with High Electrocatalytic Activity.  

PubMed

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

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

2015-02-01

41

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

42

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

PubMed

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

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

2014-05-01

43

Efficient metal-free electrocatalysts for oxygen reduction: polyaniline-derived N- and O-doped mesoporous carbons.  

PubMed

The oxygen reduction reaction (ORR)-one of the two half-reactions in fuel cells-is one of the bottlenecks that has prevented fuel cells from finding a wide range of applications today. This is because ORR is inherently a sluggish reaction; it is also because inexpensive and sustainable ORR electrocatalysts that are not only efficient but also are based on earth-abundant elements are hard to come by. Herein we report the synthesis of novel carbon-based materials that can contribute to solving these challenges associated with ORR. Mesoporous oxygen- and nitrogen-doped carbons were synthesized from in situ polymerized mesoporous silica-supported polyaniline (PANI) by carbonization of the latter, followed by etching away the mesoporous silica template from it. The synthetic method also allowed the immobilization of different metals such as Fe and Co easily into the system. While all the resulting materials showed outstanding electrocatalytic activity toward ORR, the metal-free, PANI-derived mesoporous carbon (dubbed PDMC), in particular, exhibited the highest activity, challenging conventional paradigms. This unprecedented activity by the metal-free PDMC toward ORR was attributed to the synergetic activities of nitrogen and oxygen (or hydroxyl) species that were implanted in it by PANI/mesoporous silica during pyrolysis. PMID:23646856

Silva, Rafael; Voiry, Damien; Chhowalla, Manish; Asefa, Tewodros

2013-05-29

44

Paramagnetic muon states in mesoporous carbon materials  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

45

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

46

Synthesis of Nitrogen-Doped Mesoporous Carbon Spheres with Extra-Large Pores through Assembly of Diblock Copolymer Micelles.  

PubMed

The synthesis of highly nitrogen-doped mesoporous carbon spheres (NMCS) is reported. The large pores of the NMCS were obtained through self-polymerization of dopamine (DA) and spontaneous co-assembly of diblock copolymer micelles. The resultant narrowly dispersed NMCS possess large mesopores (ca. 16?nm) and small particle sizes (ca. 200?nm). The large pores and small dimensions of the N-heteroatom-doped carbon spheres contribute to the mass transportation by reducing and smoothing the diffusion pathways, leading to high electrocatalytic activity. PMID:25393650

Tang, Jing; Liu, Jian; Li, Cuiling; Li, Yunqi; Tade, Moses O; Dai, Sheng; Yamauchi, Yusuke

2015-01-01

47

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

48

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

SciTech Connect

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

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

2009-01-01

49

Mesoporous carbons with self-assembled surfaces of defined crystal orientation.  

PubMed

The design of carbon sorbents traditionally focuses on the control of pore structure and the number and type of surface functional groups. The present paper explores the potential of also controlling the carbon crystal structure, or graphene layer orientation, in the immediate vicinity of the internal surfaces. We hypothesize that this crystal structure influences the properties of the carbon surfaces and affects the number and type of active sites for functionalization. Here a series of mesoporous carbons are fabricated by capillary infiltration of mesophase pitch (naphthalene homopolymer) into a series of controlled pore glass templates of different characteristic pore size followed by carbonization and template etching. The liquid crystalline mesogens are known to adopt perpendicular alignment (anchoring) at liquid/silica interfaces, which after carbonization lead to a high concentration of graphene edge sites at the inner surfaces. These surfaces are shown to have elevated chemical reactivity, and the pore structures are shown to be consistent with predictions of a quantitative model based on the negative replica concept. Overall, the use of mesophase pitch for templated mesoporous carbons allows systematic and simultaneous control of both pore structure and interfacial crystal structure through the well-defined rules of liquid crystal surface anchoring. PMID:19190761

Jian, Kengqing; Truong, Trung C; Hoffman, Wesley P; Hurt, Robert H

2008-02-01

50

Mesoporous carbons with self-assembled surfaces of defined crystal orientation  

PubMed Central

The design of carbon sorbents traditionally focuses on the control of pore structure and the number and type of surface functional groups. The present paper explores the potential of also controlling the carbon crystal structure, or graphene layer orientation, in the immediate vicinity of the internal surfaces. We hypothesize that this crystal structure influences the properties of the carbon surfaces and affects the number and type of active sites for functionalization. Here a series of mesoporous carbons are fabricated by capillary infiltration of mesophase pitch (naphthalene homopolymer) into a series of controlled pore glass templates of different characteristic pore size followed by carbonization and template etching. The liquid crystalline mesogens are known to adopt perpendicular alignment (anchoring) at liquid/silica interfaces, which after carbonization lead to a high concentration of graphene edge sites at the inner surfaces. These surfaces are shown to have elevated chemical reactivity, and the pore structures are shown to be consistent with predictions of a quantitative model based on the negative replica concept. Overall, the use of mesophase pitch for templated mesoporous carbons allows systematic and simultaneous control of both pore structure and interfacial crystal structure through the well-defined rules of liquid crystal surface anchoring. PMID:19190761

Jian, Kengqing; Truong, Trung C.; Hoffman, Wesley P.; Hurt, Robert H.

2008-01-01

51

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

52

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

PubMed

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

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

2014-06-01

53

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

54

Dual-pore mesoporous carbon@silica composite core-shell nanospheres for multidrug delivery.  

PubMed

Monodispersed mesoporous phenolic polymer nanospheres with uniform diameters were prepared and used as the core for the further growth of core-shell mesoporous nanorattles. The hierarchical mesoporous nanospheres have a uniform diameter of 200?nm and dual-ordered mesopores of 3.1 and 5.8?nm. The hierarchical mesostructure and amphiphilicity of the hydrophobic carbon cores and hydrophilic silica shells lead to distinct benefits in multidrug combination therapy with cisplatin and paclitaxel for the treatment of human ovarian cancer, even drug-resistant strains. PMID:24764082

Fang, Yin; Zheng, Gengfeng; Yang, Jianping; Tang, Haosha; Zhang, Yafeng; Kong, Biao; Lv, Yingying; Xu, Congjian; Asiri, Abdullah M; Zi, Jian; Zhang, Fan; Zhao, Dongyuan

2014-05-19

55

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

56

Novel pitch-based carbons with bimodal distribution of uniform mesopores.  

PubMed

A new method is proposed for the synthesis of pitch-based carbons with bimodal distribution of uniform mesopores formed by co-imprinting of spherical silica colloids and hexagonally ordered mesoporous particles of SBA-15 into mesophase pitch particles and subsequent silica dissolution. PMID:15543287

Gierszal, Kamil P; Jaroniec, Mietek

2004-11-21

57

Photocatalytic activity of a hierarchically macro/mesoporous titania.  

PubMed

Light-harvesting macroporous channels have been successfully incorporated into a mesoporous TiO(2) framework to increase its photocatalytic activity. This bimodal porous material was characterized by X-ray diffractometry in both low-angle and wide-angle ranges, N(2) adsorption-desorption analysis, scanning and transmission electron microscopy, FT-IR, and diffuse reflectance spectroscopy. Ethylene photodegradation in gas-phase medium was employed as a probe reaction to evaluate the photocatalytic reactivity of the catalysts. The results reveal that sintering temperature significantly affects the structural stability and photocatalytic activity of titania. The catalyst which calcined at 350 degrees C possessed an intact macro/mesoporous structure and showed photocatalytic reactivity about 60% higher than that of commercial P25 titania. When the sample was calcined at 500 degrees C, the macroporous structure was retained but the mesoporous structure was partly destroyed. Further heating at temperatures above 600 degrees C destroyed both macro- and mesoporous structures, accompanied by a loss in photocatalytic activity. The high photocatalytic performance of the intact macro/mesoporous TiO(2) may be explained by the existence of macrochannels that increase photoabsorption efficiency and allow efficient diffusion of gaseous molecules. PMID:15752052

Wang, Xinchen; Yu, Jimmy C; Ho, Chunman; Hou, Yidong; Fu, Xianzhi

2005-03-15

58

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

SciTech Connect

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

Yi, Bin [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China)] [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Chen, Xiaohua, E-mail: hudacxh62@yahoo.com.cn [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China)] [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Guo, Kaimin [College of Physics and Electronic Science, Changsha University of Science and Technology (China)] [College of Physics and Electronic Science, Changsha University of Science and Technology (China); Xu, Longshan [Department of Mechanical Engineering, Xiamen University of Technology, Xiamen 361024 (China)] [Department of Mechanical Engineering, Xiamen University of Technology, Xiamen 361024 (China); Chen, Chuansheng [College of Physics and Electronic Science, Changsha University of Science and Technology (China)] [College of Physics and Electronic Science, Changsha University of Science and Technology (China); Yan, Haimei; Chen, Jianghua [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China)] [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China)

2011-11-15

59

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

60

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

SciTech Connect

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

Liu, Zhi, E-mail: zhiliu@lnnu.edu.cn [Institute of Chemistry for Functionalized Materials, Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China)] [Institute of Chemistry for Functionalized Materials, Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China); Song, Yan; Yang, Yuan; Mi, Junhua; Deng, Liping [Institute of Chemistry for Functionalized Materials, Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China)] [Institute of Chemistry for Functionalized Materials, Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China)

2012-02-15

61

A new route for the preparation of mesoporous carbon materials with high performance in lithium-sulphur battery cathodes.  

PubMed

A novel method for the preparation of highly mesoporous carbon materials (Kroll-Carbons; KCs) is described based on reactive carbochlorination etching of titania nanoparticles inside a dense carbon matrix leading to mesoporous carbons with precisely controllable porosity and high performance as cathode materials for lithium-sulphur (Li-S) batteries. PMID:23698815

Oschatz, Martin; Thieme, Sören; Borchardt, Lars; Lohe, Martin R; Biemelt, Tim; Brückner, Jan; Althues, Holger; Kaskel, Stefan

2013-07-01

62

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. PMID:23762013

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

2012-01-01

63

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

PubMed

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

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

2013-12-01

64

Development of mesophase pitch derived mesoporous carbons through a commercially nanosized template.  

PubMed

Mesoporous carbons (MCs) with a high surface area (up to 900 m2/g), large pore volume (up to 2.1 cm3/g), high mesopore ratio (94%), and high yield (70%) were successfully prepared from an AR mesophase pitch, using a commercially nanosized silica template. The removal of the template provided some larger mesopores of 25-50 nm (pore I) with a surface area of ca. 300 m2/g, while the successive carbonization opened the closed pores within the carbon body to give smaller mesopores of 2-10 nm (pore II) with a similar surface area. During the carbonization of pitch precursor, the evaporation of volatile components swells the carbon to introduce the second mesopores among the domains and even microdomain units because of their rearrangements and overlappings in the process. The addition of iron salt with the silica template resulted in a remarkable increase of the surface area (ca. 300 m2/g) by introducing mesopores of 3-5 nm. The resultant MCs maintained some graphitizable natures derived from the anisotropic precursor. Their graphitization at 2400 degrees C provided the graphitic structure with large surface areas (270-460 m2/g) and mesoporosity. PMID:16584257

Qiao, W M; Song, Y; Hong, S H; Lim, S Y; Yoon, S-H; Korai, Y; Mochida, I

2006-04-11

65

Anchoring of a [Mn( salen)Cl] complex onto mesoporous carbon xerogels  

Microsoft Academic Search

Carbon xerogels were synthesized by the conventional sol–gel approach using formaldehyde and resorcinol. The wet gel was dried by two different procedures followed by carbonization, leading to mesoporous carbon xerogels with considerably different pore size distributions. The materials were subsequently oxidized with air, in order to introduce functional groups on the surface, in particular phenols, anhydrides and carbonyls. The capacity

N. Mahata; A. R. Silva; M. F. R. Pereira; C. Freire; B. de Castro; J. L. Figueiredo

2007-01-01

66

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

PubMed

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

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

2013-01-01

67

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

PubMed Central

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

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

2013-01-01

68

Fabrication of N-doped highly ordere mesoporous polymers and carbons.  

PubMed

N-doped highly ordered mesoporous carbons are synthesized via a one-step organic-organic evaporation induced self-assembly method by using phenol, formaldehyde and m-aminophenol as carbon and nitrogen sources and triblock copolymer as a structure-directing agent. The frameworks are constituted by polymer and carbon upon calcination at 350 degrees C and 900 degrees C, respectively, and N incorporates into the frameworks (0.2-1.6% in molar ratio). N-doped mesoporous carbons have high surface areas (approximately 1200 m2/g) and large pore volumes (approximately 0.65 cm3/g). Various mesostructures (p6mm and Im3m) can be obtained by simply tuning the ratio of phenol to triblock copolymer in the synthesis. With the increase of the initial amount of m-aminophenol, the graphitizing degree of mesoporous carbon increases. PMID:19441570

Feng, Cuimiao; Li, Hexing; Wan, Ying

2009-02-01

69

Adsorption of Carbon Dioxide from Gas Streams via Mesoporous Spherical-Silica Particles  

Microsoft Academic Search

A relatively new mesoporous silica sorbent for environmental protection applications (i.e., mesoporous spherical-silica particles [MSPs]), was modified by N-[3-(trimethoxysilyl)propyl]ethylenediamine (EDA) solution and was tested for its potential in the separation of carbon dioxide (CO2) from flue gas. The CO2 adsorption capacity of MSP and MSP(EDA) increased with temperature from 20 to 60 °C but decreased with temperature from 60 to

Chungsying Lu; Hsunling Bai; Fengsheng Su; Wenfa Chen; Jyh Feng Hwang; Hsiu-Hsia Lee; Walter Nakaema; Wellington Jesus; Maria Jorge; Rauda Mariani; Klara Slezakova; Dionísia Castro; Maria Pereira; Simone Morais; Cristina Delerue-Matos; Maria Alvim-Ferraz; Catherine Barton; Charles Zarzecki; Mark Russell; Marjaleena Aatamila; Pia Verkasalo; Maarit Korhonen; Marja Viluksela; Kari Pasanen; Pekka Tiittanen; Aino Nevalainen; Li Rong; Peter Nielsen; Guoqiang Zhang; Yi-Ming Kuo; Juu-En Chang; Kun-Yu Chang; Chih-C. Chao; Yeu-Juin Tuan; Guo-Ping Chang-Chien; Yongping Li; Guohe Huang; Arhontoula Chatzilazarou; Evangelos Katsoyannos; Olga Gortzi; Stavros Lalas; Yiannis Paraskevopoulos; Euthalia Dourtoglou; John Tsaknis; Tarek Abichou; Jeremy Clark; Sze Tan; Jeffery Chanton; Gary Hater; Roger Green; Doug Goldsmith; Morton Barlaz; Nathan Swan; Gang Sun; Huiqing Guo; Jonathan Peterson; Zhengmin Qian; Hung-Mo Lin; Walter Stewart; Nirav Shah; Linli Kong; Fen Xu; Denjin Zhou; Zhicao Zhu; Qingci He; Shengwen Liang; Weiqing Chen; Judith Chow; John Watson; Douglas Lowenthal; Lung-Wen Chen; Nehzat Motallebi

2010-01-01

70

Utilization of environmentally benign dicyandiamide as a precursor for the synthesis of ordered mesoporous carbon nitride and its application in base-catalyzed reactions.  

PubMed

Assisted by a new dissolution procedure, dicyandiamide (DCDA), an environmentally benign and cheap precursor, has been employed for the synthesis of mesoporous carbon nitride (CN) materials through a nanocasting approach. The synthesized mesoporous materials possessed high specific surface areas (269-715?m(2) g(-1)) with narrow pore-size distributions (about 5?nm) and faithfully replicated the mesostructures of the SBA-15 and FDU-12 templates. Several characterization techniques, including XRD, SAXS, TEM, Raman and FTIR spectroscopy, XPS, and CO2-TPD, were used to analyze the physicochemical properties of these materials and the results showed that the mesoporous CND materials had graphitic-like structures and consisted of CN heterocycles, as well as amino groups. In a series of Knoevenagel condensation reactions, as exemplified by the reaction of various aldehydes and nitriles, these mesoporous CND materials demonstrated high and stable catalytic activities, owing to an abundance of basic sites. PMID:25204431

Xu, Jie; Chen, Ting; Jiang, Quan; Li, Yong-Xin

2014-11-01

71

Fabrication of mesoporous and high specific surface area lanthanum carbide-carbon nanotube composites  

NASA Astrophysics Data System (ADS)

Mesoporous lanthanum carbide-carbon nanotube composites were produced by means of carbothermal reaction of lanthanum oxide, graphite and multi-walled carbon nanotube mixtures under high vacuum. Residual gas analysis revealed the higher reactivity of lanthanum oxide towards carbon nanotubes compared to graphite. After sintering, the composites revealed a specific surface area increasing with the amount of carbon nanotubes introduced. The meso-porosity of carbon nanotubes was maintained after thermal treatment.

Biasetto, L.; Carturan, S.; Maggioni, G.; Zanonato, P.; Di Bernardo, P.; Colombo, P.; Andrighetto, A.; Prete, G.

2009-04-01

72

Formation of nitrogen-doped mesoporous graphitic carbon with the help of melamine.  

PubMed

An efficient and facile synthesis method of nitrogen-doped mesoporous graphitic carbon (NMGC) was reported with melamine as a nitrogen source and citric acid as a carbon source. By taking advantage of the functional groups on melamine and citric acid, a uniform mixture of these two components was obtained via a self-assembly process. Accordingly, the nitrogen-doped mesoporous graphitic carbon (NMGC) can be obtained by means of the high temperature treatment. This as-prepared NMGC showed a promising potential as an anode material in lithium-ion batteries. PMID:25361052

Li, Ruimin; Cao, Anmin; Zhang, Yanjun; Li, Gen; Jiang, Feng; Li, Shumu; Chen, Daiqin; Wang, Chunru; Ge, Jiechao; Shu, Chunying

2014-12-10

73

Bromate removal from aqueous solutions by ordered mesoporous carbon.  

PubMed

We investigated the feasibility of using ordered mesoporous carbon (OMC) for bromate removal from water. Batch experiments were performed to study the influence of various experimental parameters such as the effect of contact time, adsorbent dosage, initial bromate concentration, temperature, pH and effect of competing anions on bromate removal by OMC. The adsorption kinetics indicates that the uptake rate ofbromate was rapid at the beginning: 85% adsorption was completed in 1 h and equilibrium was achieved within 3 h. The sorption process was well described with pseudo-second-order kinetics. The maximum adsorption capacity of OMC for bromate removal was 17.6 mg g(-1) at 298 K. The adsorption data fit the Freundlich model well. The amount of bromate removed was found to be proportional to the influent bromate concentration. The effects of competing anions and solution pH (3-11) were negligible. These limited data suggest that OMC can be effectively utilized for bromate removal from drinking water. PMID:24645482

Xu, Chunhua; Wang, Xiaohong; Shi, Xiaolei; Lin, Sheng; Zhu, Liujia; Che, Yaming

2014-01-01

74

Facile synthesis of hydrophilic multi-colour and upconversion photoluminescent mesoporous carbon nanoparticles for bioapplications.  

PubMed

Hydrophilic mesoporous carbon nanoparticles (MCNs) have been synthesized via an extremely facile precursor carbonization-in-hot solvent route. The synthesized MCNs show well-defined particle and pore size distribution at around 100 nm and 2.7 nm, respectively, and multicolor and upconversion photoluminescence, which endow the MCNs with multicolor/upconversion bioimaging and drug delivery properties. PMID:25371274

Kong, Qinglu; Zhang, Lingxia; Liu, Jianan; Wu, Meiying; Chen, Yu; Feng, Jingwei; Shi, Jianlin

2014-12-25

75

Towards vaporized molecular discrimination: a quartz crystal microbalance (QCM) sensor system using cobalt-containing mesoporous graphitic carbon.  

PubMed

A recent study on nanoporous carbon based materials (J. Am. Chem. Soc. 2012, 134, 2864) showed that the presence of abundant graphitized sp(2) carbon species in the frameworks led to higher affinity for aromatic hydrocarbons than their aliphatic analogues. Herein, improved understanding of the sensitive and selective detection of aromatic substances by using mesoporous carbon (MPC)-based materials, combined with a quartz crystal microbalance (QCM) sensor system, was obtained. MPCs were synthesized by direct carbonization of mesoporous polymers prepared from resol through a soft templating approach with Pluronic F127. The carbon-based frameworks can be graphitized through the addition of a cobalt source to the precursor solution, according to the catalytic activity of the cobalt nanoparticles formed during the carbonization process. From the Raman data, the degree of the graphitization was clearly increased by increasing the cobalt content and elevating the carbonization temperature. From a QCM study, it was proved that the highly graphitized MPCs exhibited a higher affinity for aromatic hydrocarbons than their aliphatic analogues. By increasing the degree of graphitization in the carbon-based pore walls, the MPCs showed both larger adsorption uptake and faster sensor response towards toxic benzene and toluene vapors. PMID:25213201

Tang, Jing; Torad, Nagy L; Salunkhe, Rahul R; Yoon, Jang-Hee; Al Hossain, Md Shahriar; Dou, Shi Xue; Kim, Jung Ho; Kimura, Tatsuo; Yamauchi, Yusuke

2014-11-01

76

Fabrication and characterization of carbon nanofiber@mesoporous carbon core-shell composite for the Li-air battery  

NASA Astrophysics Data System (ADS)

In this study, we successfully design and synthesize the mesoporous carbon coated carbon nanofibers (CNF@mesoCs) for the Li-air battery. The composites are fabricated via electrospinning technique and nanocasting strategy. After mesoporous carbon coating process, the composites have retained their original one-dimensional structure as pristine carbon nanofibers. Every nanofiber entangles with each other to form a three-dimensional cross-linked web structure. Because of the mesoporous carbon coating on carbon nanofibers, the surface area increases from 708 m2 g-1 to 2194 m2 g-1. We confirm that the mesoporous carbon coated on carbon nanofibers is well-graphitized by analysis of Raman spectra. The graphitized surface of CNF@mesoCs (4.638 S cm-1) is believed to result in their higher electrical conductivity than that of pristine carbon nanofibers (3.0759 S cm-1). Without employment of any binders and metal foams, the cathode of CNF@mesoCs exhibits high discharge capacity of 4000 mA h g-1, which is much higher than that from pristine carbon nanofibers (2750 mA h g-1). This work demonstrates that the fabricated CNF@mesoCs structures have a great potential to be employed as light-weight and efficient electrode for energy storage and conversion devices.

Song, Myeong Jun; Shin, Moo Whan

2014-11-01

77

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

PubMed

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

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

2014-05-21

78

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

SciTech Connect

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

Lv, Yingying; Fang, Yin; Qian, Xufang; Tu, Bo [Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, Fudan University, Shanghai 200433 (China); Wu, Zhangxiong [Department of Chemical Engineering, Monash University, Clayton, VIC 3800 (Australia); Asiri, Abdullah M. [Chemistry Department and The Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Zhao, Dongyuan, E-mail: dyzhao@fudan.edu.cn [Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, Fudan University, Shanghai 200433 (China); Department of Chemical Engineering, Monash University, Clayton, VIC 3800 (Australia)

2014-11-01

79

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

NASA Astrophysics Data System (ADS)

A hierarchical meso-/micro-porous graphitized carbon with uniform mesopores and ordered micropores, graphitized frameworks, and extra-high surface area of ˜2200 m2/g, was successfully synthesized through a simple one-step chemical vapor deposition process. The commercial mesoporous zeolite Y was utilized as a meso-/ micro-porous template, and the small-molecule methane was employed as a carbon precursor. The as-prepared hierarchical meso-/micro-porous carbons have homogeneously distributed mesopores as a host for electrolyte, which facilitate Li+ ions transport to the large-area micropores, resulting a high reversible lithium ion storage of 1000 mA h/g and a high columbic efficiency of 65% at the first cycle.

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

2014-11-01

80

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

SciTech Connect

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

Ma, Yuanyuan [College of Chemistry, Jilin University, Changchun 130023 (China); Key Laboratory of Fine Chemicals of College of Heilongjiang Province, Qiqihar University, Qiqihar 161006 (China); Hu, Jing [College of Chemistry, Jilin University, Changchun 130023 (China); Jia, Lihua [Key Laboratory of Fine Chemicals of College of Heilongjiang Province, Qiqihar University, Qiqihar 161006 (China); Li, Zhifang [College of Chemistry, Jilin University, Changchun 130023 (China); Kan, Qiubin, E-mail: catalysischina@yahoo.com.cn [College of Chemistry, Jilin University, Changchun 130023 (China); Wu, Shujie, E-mail: wusj@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130023 (China)

2013-05-15

81

Creation of mesopores in carbon nanotubes with improved capacities for lithium ion batteries.  

PubMed

The porous carbon nanotubes were selectively prepared from the pristine carbon nanotubes. The surface of carbon nanotubes was firstly functionalized with Fe2O3 nanoparticles and subsequent heat treatment induced CNT etching. After removal of Fe2O3 nanoparticles, mesopores were formed in carbon nanotubes and thus porous structure was obtained. The obtained material of porous carbon nanotubes with higher specific surface area and larger pore sizes was tested as anode material of lithium ion batteries and showed improved performance with respect to the pristine carbon nanotubes. PMID:25330186

Xu, Yuan; Gong, Jiang; Chen, Xuecheng; Kalenczuk, Ryszard J; Mijiowska, Ewa; Liu, Wenbin; Tang, Tao

2014-12-01

82

A novel mesoporous carbon@silicon-silica nanostructure for high-performance Li-ion battery anodes.  

PubMed

A novel hierarchical nanostructure with graphite-like carbon and small Si nanocrystals, respectively, encapsulated in the mesopores and embedded in the silica framework of mesoporous silica nanoparticles has been facilely constructed and used as an anode for Li-ion batteries, which exhibits high specific storage capacity and extraordinarily high cycling stability. PMID:25264582

He, Qianjun; Xu, Chaohe; Luo, Jianqiang; Wu, Wei; Shi, Jianlin

2014-11-21

83

Mesoporous magnetic carbon nanocomposite fabrics for highly efficient Cr(VI) removal  

E-print Network

Mesoporous magnetic carbon nanocomposite fabrics for highly efficient Cr(VI) removal Jiahua Zhu assisted heating are advanced adsorbents in the removal of Cr(VI) with a much higher removal capacity of 3 nanostructures have proven to be efficient materials for heavy metal removal by reduction or adsorption.28­30 Due

Guo, John Zhanhu

84

Cite this: RSC Advances, 2013, 3, 16 Mesoporous carbon with uniquely combined  

E-print Network

Cite this: RSC Advances, 2013, 3, 16 Mesoporous carbon with uniquely combined electrochemical, Accepted 16th October 2012 DOI: 10.1039/c2ra22279e www.rsc.org/advances J. B. Xu and T. S. Zhao* The design and mass transport issues. High performance fuel cell electrode materials require nanoarchitectures

Zhao, Tianshou

85

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

86

Fluorination of "brick and mortar" soft-templated graphitic ordered mesoporous carbons for high  

E-print Network

Fluorination of "brick and mortar" soft-templated graphitic ordered mesoporous carbons for high power lithium-ion battery Pasquale F. Fulvio,a Gabriel M. Veith,b Jamie L. Adcock,c Suree S. Brown composites prepared by the "brick and mortar" method were fluorinated using F2 and investigated as cathodes

Geohegan, David B.

87

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

SciTech Connect

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

Peter Zalupski; Rocklan McDowell; Guy Dutech

2014-10-01

88

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

SciTech Connect

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

Zhang, Wei-Min, E-mail: chm_zhangwm@ujn.edu.cn [School of Chemistry and Chemical Engineering, University of Jinan (China); Jiang, Yao-Quan [School of Chemistry and Chemical Engineering, University of Jinan (China); Cao, Xiao-Yan [Key Laboratory of Marine Chemistry Theory and Technology, Ocean University of China, Ministry of Education (China); Chen, Meng; Ge, Dong-Lai [School of Chemistry and Chemical Engineering, University of Jinan (China); Sun, Zhong-Xi, E-mail: sunzx@ujn.edu.cn [School of Chemistry and Chemical Engineering, University of Jinan (China)

2013-10-15

89

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

PubMed

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

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

2014-08-15

90

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

SciTech Connect

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

Li Siheng [State Key Laboratory of Electroanalytical Chemistry, and Jilin Provincial Key Laboratory of Advanced Low-carbon Chemical Power, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin St., Changchun 130022 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Qi Li, E-mail: qil@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, and Jilin Provincial Key Laboratory of Advanced Low-carbon Chemical Power, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin St., Changchun 130022 (China); Lu Lehui; Wang Hongyu [State Key Laboratory of Electroanalytical Chemistry, and Jilin Provincial Key Laboratory of Advanced Low-carbon Chemical Power, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin St., Changchun 130022 (China)

2013-01-15

91

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

2013-09-15

92

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

93

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

PubMed

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

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

2014-10-24

94

Hydrothermal synthesis of ordered mesoporous carbons from a biomass-derived precursor for electrochemical capacitors.  

PubMed

Here, we report the reproducible synthesis of highly ordered mesoporous carbons (OMCs) with a 2D hexagonal mesostructure via a facile hydrothermal method employing ?-cyclodextrin as a renewable and environmentally-friendly carbon precursor, which gives the OMCs a high surface area and micropore surface areas, as well as an oxygenated surface. As a supercapacitor electrode, these OMCs exhibit a high specific capacitance and a high electrochemical stability. PMID:25374331

Feng, Shanshan; Li, Wei; Wang, Jinxiu; Song, Yanfang; Elzatahry, Ahmed A; Xia, Yongyao; Zhao, Dongyuan

2014-12-21

95

Pyrolytic Synthesis of Carbon Nanotubes from Sucrose on a Mesoporous Silicate  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

96

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

SciTech Connect

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

Fulvio, Pawquale F [Kent State University; Liang, Chengdu [ORNL; Dai, Sheng [ORNL; Jaroniec, Mietek [Kent State University

2009-01-01

97

Highly reversible and large lithium storage in mesoporous si/c nanocomposite anodes with silicon nanoparticles embedded in a carbon framework.  

PubMed

A magnesiothermic reduction approach is designed to synthesize mesoporous Si/C nanocomposites with ultrasmall, uniform silicon nanoparticles (ca. 3 nm) embedded in a rigid mesoporous carbon framework. The resultant mesoporous Si/C nanocomposites present excellent performance with high reversible capacity, good Coulombic efficiency and rate capability, and outstanding cycling stability in lithium-ion battery applications. PMID:25164312

Zhang, Renyuan; Du, Yuanjin; Li, Dan; Shen, Dengke; Yang, Jianping; Guo, Zaiping; Liu, Hua Kun; Elzatahry, Ahmed A; Zhao, Dongyuan

2014-10-22

98

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

SciTech Connect

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

Fukuyama, H.; Terai, S. [Toyo Engineering Corp., Chiba (Japan). Technological Research Center

2007-07-01

99

Magnetic mesoporous Fe/carbon aerogel structures with enhanced arsenic removal efficiency.  

PubMed

Wastewater treatment has drawn significant research attention due to its associated environmental issues. Adsorption is a promising method for treating wastewater. The development of an adsorbent with a high surface area is important. Therefore, we successfully developed mesoporous Fe/carbon aerogel (CA) structures with high specific surface areas of 48 7m(2)/g via the carbonization of composite Fe3O4/phenol-formaldehyde resin structures, which were prepared using a hydrothermal process with the addition of phenol. The mesoporous Fe/CA structures were further used for the adsorption of arsenic ions with a maximum arsenic-ion uptake of calculated 216.9 mg/g, which is higher than that observed for other arsenic adsorbents. Ferromagnetic behavior was observed for the as-prepared mesoporous Fe/CA structures with an excellent response to applied external magnetic fields. As a result, the adsorbent Fe/CA structures can be easily separated from the solution using an external magnetic field. This study develops the mesoporous Fe/CA structures with high specific surface areas and an excellent response to an applied external magnetic field to provide a feasible approach for wastewater treatment including the removal of arsenic ions. PMID:24559703

Lin, Yi-Feng; Chen, Jia-Ling

2014-04-15

100

Numerical Study of Thermal Conductivities of Carbon-Based Mesoporous Composites  

NASA Astrophysics Data System (ADS)

The thermal conductivities of ordered mesoporous carbon CMK-3 filled with Al nanoclusters were studied in this article. CMK-3 is a typical example of carbon rods which are arranged in a relatively regular two-dimensional hexagonal array. The initial structure of CMK-3 was generated from the amorphous carbon and validated by XRD simulation which is coincident with experimental data. The thermal conductivities of carbon rods in CMK-3 and Al nanoclusters with 133 atoms were simulated by an equilibrium molecular dynamics method. Then, the effective thermal conductivity (ETC) of a mesoporous composite, CMK-3 filled with , was obtained via one-dimensional heat conduction analysis. The influences of the substrate porosity, nanocluster filling ratio, and temperature were discussed. As an anisotropic material, ETCs along the and directions are extremely poor, due to the overwhelming effect of the air thermal resistance. However, in the direction, the ETC improves almost linearly as the porosity decreases, and the value is much higher than those of and directions. In the case of a 70 % filling ratio, when the porosity is below 59.7 %, the ETC in the direction exceeds the thermal conductivity of Al nanoclusters and approaches a peak value around the melting temperature of nanoclusters. The results indicate that the carbon-based mesoporous CMK-3 filled with Al nanoclusters might become a promising phase change material.

Feng, Daili; Feng, Yanhui; Zhang, Xinxin

2014-10-01

101

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

102

Mesoporous carbon-carbon nanotube-sulfur composite microspheres for high-areal-capacity lithium-sulfur battery cathodes.  

PubMed

Lithium-sulfur (Li-S) batteries offer theoretical energy density much higher than that of lithium-ion batteries, but their development faces significant challenges. Mesoporous carbon-sulfur composite microspheres are successfully synthesized by combining emulsion polymerization and the evaporation-induced self-assembly (EISA) process. Such materials not only exhibit high sulfur-specific capacity and excellent retention as Li-S cathodes but also afford much improved tap density, sulfur content, and areal capacity necessary for practical development of high-energy-density Li-S batteries. In addition, when incorporated with carbon nanotubes (CNTs) to form mesoporous carbon-CNT-sulfur composite microspheres, the material demonstrated superb battery performance even at a high current density of 2.8 mA/cm(2), with a reversible capacity over 700 mAh/g after 200 cycles. PMID:24090278

Xu, Terrence; Song, Jiangxuan; Gordin, Mikhail L; Sohn, Hiesang; Yu, Zhaoxin; Chen, Shuru; Wang, Donghai

2013-11-13

103

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

SciTech Connect

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

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

2010-03-22

104

Supercritical Carbon Dioxide Swelling of Fluorinated and Hydrocarbon Surfactant Templates in Mesoporous Silica Thin Films  

Microsoft Academic Search

The penetration of compressed CO2 in hydrocarbon and fluorocarbon regions of concentrated surfactant mesophases are interpreted from differences in the CO2-processed pore expansion of mesoporous silica thin films templated by three surfactants containing varying degrees of hydrocarbon and fluorocarbon functionality. Ordered silica thin films are synthesized for the first time using the 16-carbon (C16) partly fluorinated surfactant, 11,11,12,12,13,13,14,14,15,15,16,16,16-tridecafluorocetyl pyridinium bromide

Kaustav Ghosh; Hans-Joachim Lehmler; Stephen E. Rankin; Barbara L. Knutson

105

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

PubMed

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

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

2014-12-15

106

Adsorption equilibrium and kinetics of CO2, CH4, N2O, and NH3 on ordered mesoporous carbon.  

PubMed

Ordered mesoporous carbon was synthesized by a self-assembly technique and characterized with TEM, Raman spectroscopy, and nitrogen adsorption/desorption for its physical and pore textural properties. The high BET specific surface area (798 m(2)/g), uniform mesopore-size distribution with a median pore size of 62.6 Å, and large pore volume (0.87 cm(3)/g) make the ordered mesoporous carbon an ideal adsorbent for gas separation and purification applications. Adsorption equilibrium and kinetics of carbon dioxide, methane, nitrous oxide, and ammonia on the ordered mesoporous carbon were measured at 298 K and gas pressures up to 800 Torr. The adsorption equilibrium capacities on the ordered mesoporous carbon at 298 K and 800 Torr for ammonia, carbon dioxide, nitrous oxide, and methane were found to be 6.39, 2.39, 1.5, and 0.53 mmol/g, respectively. Higher adsorption uptakes of methane (3.26 mmol/g at 100 bar) and carbon dioxide (2.21 mmol/g at 13 bar) were also observed at 298 K and elevated pressures. Langmuir, Freundlich, and Toth adsorption equilibrium models were used to correlate all the adsorption isotherms, and a simplified gas diffusion model was applied to analyze the adsorption kinetics data collected at 298 K and four different gas pressures up to 800 Torr. PMID:20185144

Saha, Dipendu; Deng, Shuguang

2010-05-15

107

Preparation of mesoporous carbon-carbon nanotube composites using the template method.  

PubMed

Reported herein is a simple template method for preparing mesoporous carbons (MPCs) from a mesophase pitch, using homemade nano-sized MgOs and MgO-carbon nanotube (CNT) composites as templates. Nano-sized MgO particles containing iron-molybdenum were synthesized through the heat treatment of the precursor ash, and the MgO-CNT composites were prepared via catalytic chemical vapor deposition of CH4 over the MgO-based particles. MPCs with a high surface area of 443-578 m2/g were obtained through the heat treatment of well-mixed mesophase pitch-MgO (or MgO-CNT), followed by mild-acid treatment to remove the MgO and other catalyst components. All the materials (the precursors, nano-particles, and MPCs) were analyzed via powder X-ray diffraction, N2 adsorption-desorption isotherms, scanning electron microscopy, and high resolution transmission electron microscopy. The formation of the pore structure in the MPCs is discussed, and the potential application of the MPC-CNT composite is demonstrated through cyclic voltammetry. PMID:22121604

Nam, Kidon; Lim, Seongyop; Kim, Sang-Kyung; Peck, Donghyun; Jung, Doohwan

2011-07-01

108

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

PubMed

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

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

2014-09-23

109

Metal-support interaction in platinum and palladium nanoparticles loaded on nitrogen-doped mesoporous carbon for oxygen reduction reaction.  

PubMed

Mesoporous carbons are highly porous materials, which show large surface area, chemical inertness and electrochemical performances superior to traditional carbon material. In this study, we report the preparation of nitrogen-doped and undoped mesoporous carbons by an optimized hard template procedure employing silica as template, sucrose and ammonia as carbon and nitrogen source, respectively. Surface area measurements assert a value of 900 and 600 m(2) g(-1) for the best doped and undoped samples, respectively. Such supports were then thoroughly characterized by surface science and electron microscopy tools. Afterward, they were decorated with Pt and Pd nanoparticles, and it was found that the presence of nitrogen defects plays a significant role in improving the metal particles dimension and dispersion. In fact, when doped supports are used, the resulting metal nanoparticles are smaller (2-4 nm) and less prone to aggregation. Photoemission measurements give evidence of a binding energy shift, which is consistent with the presence of an electronic interaction between nitrogen atoms and the metal nanoparticles, especially in the case of Pd. The catalytic properties of electrodes decorated with such catalyst/support systems were investigated by linear sweep voltammetry and by rotating disk electrode measurements, revealing excellent stability and good activity toward oxygen reduction reaction (ORR). In particular, although Pd nanoparticles always result in lower activity than Pt ones, both Pt and Pd electrodes based on the N-doped supports show an increased activity toward ORR with respect to the undoped ones. At the same mass loading, the Tafel slope and the stability test of the Pt@N-doped electrocatalysts indicate superior performances to that of a commercial Pt@C catalysts (30 wt % Pt on Vulcan XC-72, Johnson Matthey). PMID:25525718

Perini, Lorenzo; Durante, Christian; Favaro, Marco; Perazzolo, Valentina; Agnoli, Stefano; Schneider, Oliver; Granozzi, Gaetano; Gennaro, Armando

2015-01-21

110

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

111

Hydrogen Ion Supercapacitor: A New Hybrid Configuration of Highly Dispersed MnO2 in Porous Carbon Coupled with Nitrogen-Doped Highly Ordered Mesoporous Carbon with Enhanced H-Insertion.  

PubMed

A new configuration of hydrogen ion supercapacitors was reported. A positive electrode composed of pseudocapacitive MnO2, highly dispersed into active porous carbon through an impregnation method, was combined with a nitrogen-doped highly ordered mesoporous carbon with enhanced electrochemical hydrogen insertion capacity as a negative electrode. During the operation, hydrogen ion shuttled between MnO2 and carbon electrodes. The MnO2 was formed on the surface of nanostructured carbon through a spontaneous redox reaction. Operating in an aqueous neutral solution, the hybrid device demonstrated an extended working voltage to ?2.1 V with good cycle life. PMID:25458840

Qu, Deyu; Wen, Jianfeng; Liu, Dan; Xie, Zhizhong; Zhang, Xuran; Zheng, Dong; Lei, Jiahen; Zhong, Wei; Tang, Haolin; Xiao, Liang; Qu, Deyang

2014-12-24

112

Synthesis of nitrogen-containing ordered mesoporous carbon as a metal-free catalyst for selective oxidation of ethylbenzene.  

PubMed

Nitrogen-containing ordered mesoporous carbon (NOMC) was synthesized by using m-aminophenol (MAP) as a carbon and nitrogen co-precursor via a co-assembly process with F127 in aqueous phase and exhibited a good catalytic performance for selective oxidation of ethylbenzene. PMID:24993634

Wang, Jia; Liu, Hongyang; Gu, Xianmo; Wang, Haihua; Su, Dang Sheng

2014-08-21

113

Highly ordered magnetic mesoporous silicas for effective elimination of carbon monoxide  

SciTech Connect

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

Lee, Jiho [Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of); Department of Chemistry, Inha University, Incheon 402-751 (Korea, Republic of); Ho Chang, Jeong, E-mail: jhchang@kicet.re.kr [Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of)

2012-04-15

114

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

PubMed

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

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

2014-01-28

115

Preparation and drug release behavior of temperature-responsive mesoporous carbons  

NASA Astrophysics Data System (ADS)

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

Wang, Xiufang; Liu, Ping; Tian, Yong

2011-06-01

116

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

SciTech Connect

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

Dai, Sheng [ORNL; Shao, Yuyan [Pacific Northwest National Laboratory (PNNL); Wang, Xiqing [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

2010-01-01

117

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

NASA Astrophysics Data System (ADS)

The composites of ordered mesoporous carbon (OMC) and graphene nano-sheets (GNS) are prepared by mixing OMC with different weight ratios of GNS, and utilized as counter electrode (CE) materials for dye-sensitized solar cells (DSSCs). Electrochemical impedance spectroscopy, Tafel polarization, and cyclic voltammetry measurements demonstrate that the OMC/GNS CEs display the enhanced electron transport property and fast reduction rate of 3-in comparison with those of the individual OMC and GNS CEs, due to the combination of superior electrical conductivity of GNS and good catalytic activity of OMC. Under AM 1.5 irradiation (100 mW cm-2), the DSSCs based on the OMC/GNS CEs show a maximum power conversion efficiency of 6.82%, which is comparable to 7.08% of the cell with the conventional Pt CE at the same experimental conditions, suggesting that the OMC/GNS composites are one of advanced CE materials for low-cost DSSCs.

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

2015-01-01

118

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

PubMed

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

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

2014-08-15

119

Enhancing the photocatalytic activity of bulk g-C3N4 by introducing mesoporous structure and hybridizing with graphene.  

PubMed

Bulk graphitic carbon nitride (CN) suffers from small surface area and high recombination of charge carriers, which result in low photocatalytic activity. To enhance the activity of g-C3N4, the surface area should be enlarged and charge carrier separation should be promoted. In this work, a combined strategy was employed to dramatically enhance the activity of bulk g-C3N4 by simultaneously introducing mesoporous structure and hybridizing with graphene/graphene oxide. The mesoporous g-C3N4/graphene (MCN-G) and mesoporous g-C3N4/graphene oxide (MCN-GO) nanocomposites with enhanced photocatalytic activity (NO removal ratio of 64.9% and 60.7%) were fabricated via a facile sonochemical method. The visible light-harvesting ability of MCN-G and MCN-GO hybrids was enhanced and the conduction band was negatively shifted when 1.0 wt% graphene/graphene oxide was incorporated into the matrix of MCN. As electronic conductive channels, the G/GO sheets could efficiently facilitate the separation of chare carriers. MCN-G and MCN-GO exhibited drastically enhanced visible light photocatalytic activity toward NO removal. The NO removal ratio increased from 16.8% for CN to 64.9% for MCN-G and 60.7% for MCN-GO. This enhanced photocatalytic activity could be attributed to the increased surface area and pore volume, improved visible light utilization, enhanced reduction power of electrons, and promoted separation of charge carriers. This work demonstrates that a combined strategy is extremely effective for the development of active photocatalysts in environmental and energetic applications. PMID:25265582

Li, Yuhan; Sun, Yanjuan; Dong, Fan; Ho, Wing-Kei

2014-12-15

120

Mesoporous W??O?? hollow spheres as highly active photocatalysts.  

PubMed

Mesoporous hollow W18O49 spheres were fabricated by a facile solvent-induced assembly method using anhydrous WCl6 as a precursor and CH3COOH as a solvent. This unique structure exhibited remarkably enhanced photocatalytic and photoelectrocatalytic performance than other morphologies like urchin and nanowire due to the simultaneous enhancement in light harvesting, surface area and adsorption capability. PMID:24995560

Huang, Zhen-Feng; Song, Jiajia; Pan, Lun; Lv, Fenglei; Wang, Qingfa; Zou, Ji-Jun; Zhang, Xiangwen; Wang, Li

2014-09-28

121

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

NASA Astrophysics Data System (ADS)

In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg2+ doping (G/LFMP) were synthesized by a modified rheological phase method to improve the speed of lithium storage as well as cycling stability. The mesoporous structure of LiFePO4 nanocrystals was designed and realized by introducing the bead milling technique, which assisted in forming sucrose-pyrolytic carbon nanoparticles as the template for generating mesopores. For comparison purposes, samples modified only with graphene (G/LFP) or Mg2+ doping (LFMP) as well as pure LiFePO4 (LFP) were also prepared and investigated. Microscopic observation and nitrogen sorption analysis have revealed the mesoporous morphologies of the as-prepared composites. X-ray diffraction (XRD) and Rietveld refinement data demonstrated that the Mg-doped LiFePO4 is a single olivine-type phase and well crystallized with shortened Fe-O and P-O bonds and a lengthened Li-O bond, resulting in an enhanced Li+ diffusion velocity. Electrochemical properties have also been investigated after assembling coin cells with the as-prepared composites as the cathode active materials. Remarkably, the G/LFMP composite has exhibited the best electrochemical properties, including fast lithium storage performance and excellent cycle stability. That is because the modification of graphene provided active sites for nuclei, restricted the in situ crystallite growth, increased the electronic conductivity and reduced the interface reaction current density, while, Mg2+ doping improved the intrinsically electronic and ionic transfer properties of LFP crystals. Moreover, in the G/LFMP composite, the graphene component plays the role of ``cushion'' as it could quickly realize capacity response, buffering the impact to LFMP under the conditions of high-rate charging or discharging, which results in a pre-eminent rate capability and cycling stability.In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg2+ doping (G/LFMP) were synthesized by a modified rheological phase method to improve the speed of lithium storage as well as cycling stability. The mesoporous structure of LiFePO4 nanocrystals was designed and realized by introducing the bead milling technique, which assisted in forming sucrose-pyrolytic carbon nanoparticles as the template for generating mesopores. For comparison purposes, samples modified only with graphene (G/LFP) or Mg2+ doping (LFMP) as well as pure LiFePO4 (LFP) were also prepared and investigated. Microscopic observation and nitrogen sorption analysis have revealed the mesoporous morphologies of the as-prepared composites. X-ray diffraction (XRD) and Rietveld refinement data demonstrated that the Mg-doped LiFePO4 is a single olivine-type phase and well crystallized with shortened Fe-O and P-O bonds and a lengthened Li-O bond, resulting in an enhanced Li+ diffusion velocity. Electrochemical properties have also been investigated after assembling coin cells with the as-prepared composites as the cathode active materials. Remarkably, the G/LFMP composite has exhibited the best electrochemical properties, including fast lithium storage performance and excellent cycle stability. That is because the modification of graphene provided active sites for nuclei, restricted the in situ crystallite growth, increased the electronic conductivity and reduced the interface reaction current density, while, Mg2+ doping improved the intrinsically electronic and ionic transfer properties of LFP crystals. Moreover, in the G/LFMP composite, the graphene component plays the role of ``cushion'' as it could quickly realize capacity response, buffering the impact to LFMP under the conditions of high-rate charging or discharging, which results in a pre-eminent rate capability and cycling stability. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr04611g

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

2013-12-01

122

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

123

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

PubMed

In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg(2+) doping (G/LFMP) were synthesized by a modified rheological phase method to improve the speed of lithium storage as well as cycling stability. The mesoporous structure of LiFePO4 nanocrystals was designed and realized by introducing the bead milling technique, which assisted in forming sucrose-pyrolytic carbon nanoparticles as the template for generating mesopores. For comparison purposes, samples modified only with graphene (G/LFP) or Mg(2+) doping (LFMP) as well as pure LiFePO4 (LFP) were also prepared and investigated. Microscopic observation and nitrogen sorption analysis have revealed the mesoporous morphologies of the as-prepared composites. X-ray diffraction (XRD) and Rietveld refinement data demonstrated that the Mg-doped LiFePO4 is a single olivine-type phase and well crystallized with shortened Fe-O and P-O bonds and a lengthened Li-O bond, resulting in an enhanced Li(+) diffusion velocity. Electrochemical properties have also been investigated after assembling coin cells with the as-prepared composites as the cathode active materials. Remarkably, the G/LFMP composite has exhibited the best electrochemical properties, including fast lithium storage performance and excellent cycle stability. That is because the modification of graphene provided active sites for nuclei, restricted the in situ crystallite growth, increased the electronic conductivity and reduced the interface reaction current density, while, Mg(2+) doping improved the intrinsically electronic and ionic transfer properties of LFP crystals. Moreover, in the G/LFMP composite, the graphene component plays the role of "cushion" as it could quickly realize capacity response, buffering the impact to LFMP under the conditions of high-rate charging or discharging, which results in a pre-eminent rate capability and cycling stability. PMID:24287590

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

2014-01-21

124

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

PubMed

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

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

2015-01-21

125

Transport of Ions in Mesoporous Carbon Electrodes during Capacitive Deionization of High-Salinity Solutions.  

PubMed

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

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

2015-01-27

126

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

PubMed

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

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

2014-09-01

127

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

PubMed Central

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

2014-01-01

128

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

NASA Astrophysics Data System (ADS)

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

Zhang, Deyang; Yan, Hailong; Lu, Yang; Qiu, Kangwen; Wang, Chunlei; Tang, Chengchun; Zhang, Yihe; Cheng, Chuanwei; Luo, Yongsong

2014-03-01

129

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

PubMed

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

Zhang, Deyang; Yan, Hailong; Lu, Yang; Qiu, Kangwen; Wang, Chunlei; Tang, Chengchun; Zhang, Yihe; Cheng, Chuanwei; Luo, Yongsong

2014-01-01

130

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

PubMed

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

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

2015-01-21

131

Electrochemical control of ion transport through a mesoporous carbon membrane  

SciTech Connect

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

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

2014-01-01

132

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

2012-06-15

133

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), N 2 adsorption/desorption isotherms and transmission electron microscopy (TEM) are used to characterize the composites derived at the hydrothermal temperature of 125, 150, 175, 200, 250, 275 and 300 °C. The formation of nanosized nickel compounds, fully inside the mesopore system, was confirmed with XRD and TEM. An N 2 adsorption/desorption isotherms measurements still revealed mesoporosity for the host/guest compounds. It is noteworthy that an OMC/nickel nitrate hydroxide hydrate composite (OMCN-150) exhibits more excellent performance. Based on the various hydrothermal temperatures of the composite, the capacitance of an OMCN-150 delivering the best electrochemical performance is about 2.4 (5 mV s -1) and 1.5 (50 mV s -1) times of the pristine OMC. The capacitance retention of an OMCN-150 is 96.1%, which indicates that the electrochemical performance of the supercapacitor is improved greatly, and represents novel research and significant advances in the field of electrode composite materials for supercapacitor.

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

2010-12-01

134

Magnetic ?-Fe2O3, Fe3O4, and Fe nanoparticles confined within ordered mesoporous carbons as efficient microwave absorbers.  

PubMed

A series of magnetic ?-Fe2O3, Fe3O4, and Fe nanoparticles have been successfully introduced into the mesochannels of ordered mesoporous carbons by the combination of the impregnation of iron salt precursors and then in situ hydrolysis, pyrolysis and reduction processes. The magnetic nanoparticles are uniformly dispersed and confined within the mesopores of mesoporous carbons. Although the as-prepared magnetic mesoporous carbon composites have high contents of magnetic components, they still possess very high specific surface areas and pore volumes. The magnetic hysteresis loops measurements indicate that the magnetic constituents are poorly-crystalline nanoparticles and their saturation magnetization is evidently smaller than bulky magnetic materials. The confinement of magnetic nanoparticles within the mesopores of mesoporous carbons results in the decrease of the complex permittivity and the increase of the complex permeability of the magnetic nanocomposites. The maximum reflection loss (RL) values of -32 dB at 11.3 GHz and a broad absorption band (over 2 GHz) with RL values <-10 dB are obtained for 10-Fe3O4-CMK-3 and 10-?-Fe2O3-CMK-3 composites in a frequency range of 8.2-12.4 GHz (X-band), showing their great potentials in microwave absorption. This research opens a new method and idea for developing novel magnetic mesoporous carbon composites as high-performance microwave absorbing materials. PMID:25562071

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

2015-02-01

135

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

SciTech Connect

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

Liu, Shouxin, E-mail: liushouxin@126.com [Key Laboratory of Bio-Based Material Science and Technology of The Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Huang, Zhanhua; Wang, Rui [Key Laboratory of Bio-Based Material Science and Technology of The Ministry of Education, Northeast Forestry University, Harbin 150040 (China)

2013-07-15

136

High performance sulfur, nitrogen and carbon doped mesoporous anatase-brookite TiO? photocatalyst for the removal of microcystin-LR under visible light irradiation.  

PubMed

Carbon, nitrogen and sulfur (C, N and S) doped mesoporous anatase-brookite nano-heterojunction titania photocatalysts have been synthesized through a simple sol-gel method in the presence of triblock copolymer Pluronic P123. XRD and Raman spectra revealed the formation of anatase and brookite mixed phases. XPS spectra indicated the presence of C, N and S dopants. The TEM images demonstrated the formation of almost monodisperse titania nanoparticles with particle sizes of approximately 10nm. N2 isotherm measurements confirmed that both doped and undoped titania anatase-brookite materials have mesoporous structure. The photocatalytic degradation of the cyanotoxin microcystin-LR (MC-LR) has been investigated using these novel nanomaterials under visible light illumination. The photocatalytic efficiency of the mesoporous titania anatase-brookite photocatalyst dramatically increased with the addition of the C, N and S non-metal, achieving complete degradation (? 100 %) of MC-LR. The results demonstrate the advantages of the synthetic approach and the great potential of the visible light activated C, N, and S doped titania photocatalysts for the treatment of organic micropollutants in contaminated waters under visible light. PMID:25238189

El-Sheikh, Said M; Zhang, Geshan; El-Hosainy, Hamza M; Ismail, Adel A; O'Shea, Kevin E; Falaras, Polycarpos; Kontos, Athanassios G; Dionysiou, Dionysios D

2014-09-15

137

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

PubMed Central

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

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

2013-01-01

138

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

2009-06-21

139

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

140

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

PubMed

In this contribution, nitrogen- and sulfur-codoped 3D cubic-ordered mesoporous carbon (KNOMC) materials with controlled dopant content (10.0-4.6 atom % for nitrogen and 0.94-0.75 atom % for sulfur) are presented, using KIT-6 as the template and pyrrole as the precursor, and its supercapacitive behavior is also investigated. The presented materials exhibit excellent supercapacitive performance by combining electrical double-layer capacitance and pseudocapacitance as well as the enhanced wettability and improved conductivity generated from the incorporation of nitrogen and sulfur into the framework of carbon materials. The specific capacitance of the presented materials reaches 320 F g(-1) at a current density of 1 A g(-1), which is significantly larger than that of the pristine-ordered mesoporous carbon reported in the literature and can even compete with some metal oxides and conducting polymers. PMID:24471376

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

2014-02-26

141

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

142

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

143

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

PubMed

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

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

2014-09-15

144

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

SciTech Connect

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

Song, Lingyan; Feng, Dan; Lee, Hae-Jeong; Wang, Chengqing; Wu, Quanyan; Zhao, Dongyuan; Vogt, Bryan D. (On Semi); (NIST); (AZU); (Fudan)

2010-10-22

145

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

2013-11-21

146

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

147

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

PubMed

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

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

2014-01-01

148

Ammonia-assisted semicarbonization: a simple method to introduce micropores without damaging a 3D mesoporous carbon nanonetwork structure.  

PubMed

A simple and effective way to introduce micropores into skeleton of carbon aerogel (CA) without damaging its unique 3D mesoporous nanonetwork has been successfully developed by NH3-assisted semicarbonization. During the NH3-assisted semicarbonization process, nitrogen functional groups with high thermo-decomposable ability like pyrrolic/pyridine and pyridinic can be introduced into the semicarbonized aerogel framework by substituting oxygen functional groups with low thermo-decomposable ability like C?O quinone-type groups and then escape from the resultant CA framework during the subsequent carbonization, thus forming abundant micropores inside carbon framework under the circumstance of keeping wonderful stability of mesoporous nanonetwork structure. Compared with the traditional CA without NH3 assistance during semicarbonization, the as-prepared novel CA represents a much higher surface area (1100 vs 620 m(2) g(-1)) and a compatible mesopore structure. Meanwhile, such a NH3 treatment confers many useful nitrogen functional groups on the nanonetwork framework. The novel CA is then used as electrode material of supercapacitors and shows a much higher capacitance and comparable high capacitance retention as compared with the traditional CA. PMID:25035264

Yang, Xiaoqing; Zhang, Guoqing; Zhong, Meiling; Wu, Dingcai; Fu, Ruowen

2014-08-01

149

Carbon Calculator Activity  

NSDL National Science Digital Library

In this learning activity, students use a web-based carbon calculator to determine their carbon footprint on the basis of their personal and household habits and choices. Students identify which personal activities and household choices produce the most CO2 emissions, compare their carbon footprint to the U.S. and global averages, and identify lifestyle changes they can make to reduce their footprint.

Environmental Literacy and Inquiry Working Group at Lehigh University

150

Fe-containing mesoporous molecular sieves materials: very active Friedel-Crafts alkylation catalysts  

Microsoft Academic Search

Benzylation of benzene has been conducted over Fe-containing zeolite molecular sieve materials prepared by different methods and exhibiting different pore sizes. It was shown that the mesoporous Fe-containing materials were very active benzylation catalysts with a monoalkylated product selectivity of 100%, and had better stability than the previously reported iron pillared clays (FePILCs). Temperature and pore size were two critical

Nongyue He; Shulin Bao; Qinhua Xu

1998-01-01

151

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

152

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. PMID:22428103

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

2012-01-01

153

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

PubMed

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

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

2015-01-15

154

Immobilization of proteolytic enzyme on highly porous activated carbon derived from rice bran  

Microsoft Academic Search

Highly porous activated carbon (HPAC) was used as carrier matrix for immobilization of acid protease (AP). Immobilization\\u000a of acid protease on mesoporous activated carbon (AP-HPAC) performs as best enzyme carrier. At pH 6.0, 250 mg acid protease\\u000a g?1 HPAC was immobilized. The optimum temperature for both free and immobilized AP activities were 50 °C. After incubation at\\u000a 50 °C, the immobilized AP maintained

A. Ganesh Kumar; S. Swarnalatha; P. Kamatchi; R. Kirubagaran; K. Perinmbam; G. Sekaran

2009-01-01

155

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

PubMed

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

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

2011-06-15

156

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

157

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

PubMed Central

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

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

2014-01-01

158

Adsorption and structural properties of ordered mesoporous carbons synthesized by using various carbon precursors and ordered siliceous P6mm and Ia3d mesostructures as templates.  

PubMed

Adsorption and structural properties of inverse carbon replicas of two ordered siliceous P6mm and Ia3d mesostructures have been studied by nitrogen adsorption, powder X-ray diffraction, and transmission electron microscopy. These carbon replicas were prepared by filling the pores of SBA-15 and KIT-6 siliceous templates with various carbon precursors followed by carbonization and silica dissolution. Sucrose, furfuryl alcohol, acenaphthene, mesophase pitch, and petroleum pitch were used to obtain inverse carbon replicas of SBA-15 and KIT-6. While structural properties of the resulting ordered mesoporous carbons are mainly determined by the hard template used, their adsorption properties depend on the type of the carbon precursor. PMID:16375291

Gierszal, Kamil P; Kim, Tae-Wan; Ryoo, Ryong; Jaroniec, Mietek

2005-12-15

159

Green and facile synthesis of an Au nanoparticles@polyoxometalate/ordered mesoporous carbon tri-component nanocomposite and its electrochemical applications.  

PubMed

The one-pot synthesis of a well-defined Au nanoparticles@polyoxometalates/ordered mesoporous carbon (Au@POMs/OMC) tri-component nanocomposite is reported, which is facile, green and rapid. The polyoxometalates were used as both reductant and bridging molecules. The formation of these composite materials was verified by a comprehensive characterization using X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectra, scanning electron microscopy, and transmission electron microscopy. The novel nanohybrids of Au@POMs/OMC can provide new features of electrocatalytic activities, because of the synergetic effects of Au nanoparticles and OMC materials. Most importantly, the amperometric measurements show that the Au@POMs/OMC nanohybrids have a high catalytic activity with a good sensitivity, long-term stability, wide linear range, low detection limit, and fast response towards acetaminophenol, H2O2, and NADH detection for application as an enzyme-free biosensor. PMID:25460901

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

2015-04-15

160

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

161

Improved electrochemical performance of SnO2-mesoporous carbon hybrid as a negative electrode for lithium ion battery applications.  

PubMed

To utilize the high specific capacity of SnO2 as an anode material in lithium-ion batteries, one has to overcome its poor cycling performance and rate capability, which result from large volume expansion (?300%) of SnO2 during charging-discharging cycles. Hence, to accommodate the volume change during cycling, SnO2 nanoparticles of 6 nm diameter were synthesized specifically only on the outer surface of the mesopores, present within mesoporous carbon (CMK-5) particles, resulting in an effective buffering layer. To that end, the synthesis process first involves the formation of 3.5 nm SnO2 nanoparticles inside the mesopores of mesoporous silica (SBA-15), the latter being used as a template subsequently to obtain SnO2-CMK-5 hybrid particles. SnO2-CMK-5 exhibits superior rate capabilities, e.g. after 30 cycles, a specific discharge capacity of 598 mA h g(-1), at a current density of 178 mA g(-1). Electrochemical impedance spectroscopy reveals that the SnO2-CMK-5 electrode undergoes a significant reduction in solid-electrolyte interfacial and charge transfer resistances, with a simultaneous increase in the diffusion coefficient of lithium ions, all these in comparison to an electrode made of only SnO2 nanoparticles. This enhances the potential of using the SnO2-CMK-5 hybrid as a negative electrode, in terms of improved discharge capacity and cycling stability, compared to other electrodes, such as only SnO2 or only CMK-5. PMID:24576943

Srinivasan, N R; Mitra, Sagar; Bandyopadhyaya, Rajdip

2014-04-14

162

One-pot hydrothermal synthesis of mesoporous Zn(x)Cd(1-x)S/reduced graphene oxide hybrid material and its enhanced photocatalytic activity.  

PubMed

We successfully synthesized mesoporous Zn(x)Cd(1-x)S/reduced graphene oxide (Z(x)CSG) hybrid materials as photocatalysts using a facile one-pot hydrothermal reaction, in which graphene oxide (GO) was easily reduced (RGO), and simultaneously Zn(x)Cd(1-x)S (Z(x)CS) nanoparticles (NPs) with a mesoporous structure were uniformly dispersed on the RGO sheets. By well tuning the band gap from 3.42 to 2.21 eV by changing the molar ratio of Zn/Cd (or Zn content), Z(x)CSG with an optimal zinc content has been found to have a significant absorption in the visible light (VL) region. In addition, under VL irradiation (? > 420 nm), Z(x)CSG also showed zinc content-dependent photocatalytic efficiencies for the degradation of methylene blue (MB). Our findings are that, among Z(x)CSG, Z(0.4)CSG displayed not only a superior photodegradation efficiency of MB (98%), but also good removal efficiency of total organic carbon (TOC) (67%). Furthermore, Z(0.4)CSG had a high photocatalytic stability, and could be used repeatedly. The enhanced photocatalytic activity for Z(0.4)CSG could be attributed to a synergistic effect between mesoporous Z(x)CS NPs and RGO, including the optimal band gap and the moderate conduction band position for ZxCS (compared to CdS), efficient separation and transfer ability of photogenerated electron/hole pairs in the presence of RGO sheets, and relatively high surface area for both mesoporous Z(x)CS NPs and RGO. PMID:25019939

Wang, Xinwei; Tian, Hongwei; Cui, Xiaoqiang; Zheng, Weitao; Liu, Yichun

2014-09-14

163

Water and small organic molecules as probes for geometric confinement in well-ordered mesoporous carbon materials.  

PubMed

Mesoporous carbon materials were synthesized employing polymers and silica gels as structure directing templates. The basic physico-chemical properties of the synthetic mesoporous materials were characterized by (1)H and (13)C MAS solid-state NMR, X-ray diffraction, transmission electron microscopy (TEM) and nitrogen adsorption measurements. The confinement effects on small guest molecules such as water, benzene and pyridine and their interactions with the pore surface were probed by a combination of variable temperature (1)H-MAS NMR and quantum chemical calculations of the magnetic shielding effect of the surface on the solvent molecules. The interactions of the guest molecules depend strongly on the carbonization temperature and the pathway of the synthesis. All the guest-molecules, water, benzene and pyridine, exhibited high-field shifts by the interaction with the surface of carbon materials. The geometric confinement imposed by the surface causes a strong depression of the melting point of the surface phase of water and benzene. The theoretical calculation of (1)H NICS maps shows that the observed proton chemical shifts towards high-field values can be explained as the result of electronic ring currents localized in aromatic groups on the surface. The dependence on the distance between the proton and the aromatic surface can be exploited to estimate the average diameter of the confinement structures. PMID:24715202

Xu, Yeping; Watermann, Tobias; Limbach, Hans-Heinrich; Gutmann, Torsten; Sebastiani, Daniel; Buntkowsky, Gerd

2014-05-28

164

Adsorption of anionic and cationic dyes on ferromagnetic ordered mesoporous carbon from aqueous solution: equilibrium, thermodynamic and kinetics.  

PubMed

Ordered mesoporous carbon (Fe-CMK-3) with iron magnetic nanoparticles was prepared by a casting process via SBA-15 silica as template and anthracene as carbon source, was used as a magnetic adsorbent for the removal of anionic dye Orange II (O II) and cationic dye methylene blue (MB) from aqueous solution. TEM and magnetometer images showed that the iron magnetic nanoparticles were successfully embedded in the interior of the mesoporous carbon. The effect of various process parameters such as temperature (25-45°C), initial concentration (100-500 mg L(-1)) and pH (2-12) were performed. Equilibrium adsorption isotherms and kinetics were also studied. The equilibrium experimental data were analyzed by the Langmuir, Freundlich, Temkin and Redlich-Peterson model. The equilibrium data for two dyes adsorption was fitted to the Langmuir, and the maximum monolayer adsorption capacity for O II and MB dyes were 269 and 316 mg g(-1), respectively. Pseudo-first-order and pseudo-second-order kinetic and intraparticle diffusion model were used to evaluate the adsorption kinetic data. The kinetic data of two dyes could be better described by the pseudo second-order model. Thermodynamic data of the adsorption process were also obtained. It was found that the adsorption process of the two dyes were spontaneous and exothermic. PMID:24973701

Peng, Xiaoming; Huang, Dengpo; Odoom-Wubah, Tareque; Fu, Dafang; Huang, Jiale; Qin, Qingdong

2014-09-15

165

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

NASA Astrophysics Data System (ADS)

Four nanoporous carbons prepared by direct carbonization of non-permanent highly porous MOF [Zn3(BTC)2.(H2O)3]n without any additional carbon precursors. The carbonization temperature plays an important role in the pore structures of the resultant carbons. The Brunauer-Emmett-Teller (BET) surface areas of four carbon materials vary from 464 to 1671 m2 g-1 for different carbonization temperature. All the four carbon materials showed a mesoporous structure centered at ca. 3 nm, high surface area and good physicochemical stability. Hydrogen, methane and carbon dioxide sorption measurements indicated that the C1000 has good gas uptake capabilities. The excess H2 uptake at 77 K and 17.9 bar can reach 32.9 mg g-1 and the total uptake is high to 45 mg g-1. Meanwhile, at 95 bar, the total CH4 uptake can reach as high as 208 mg g-1. Moreover the ideal adsorbed solution theory (IAST) prediction exhibited exceptionally high adsorption selectivity for CO2/CH4 in an equimolar mixture at 298 K and 1 bar (Sads = 27) which is significantly higher than that of some porous materials in the similar condition.

Wang, Wenjing; Yuan, Daqiang

2014-07-01

166

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

PubMed Central

Four nanoporous carbons prepared by direct carbonization of non-permanent highly porous MOF [Zn3(BTC)2·(H2O)3]n without any additional carbon precursors. The carbonization temperature plays an important role in the pore structures of the resultant carbons. The Brunauer-Emmett-Teller (BET) surface areas of four carbon materials vary from 464 to 1671?m2 g?1 for different carbonization temperature. All the four carbon materials showed a mesoporous structure centered at ca. 3?nm, high surface area and good physicochemical stability. Hydrogen, methane and carbon dioxide sorption measurements indicated that the C1000 has good gas uptake capabilities. The excess H2 uptake at 77?K and 17.9 bar can reach 32.9?mg g?1 and the total uptake is high to 45?mg g?1. Meanwhile, at 95 bar, the total CH4 uptake can reach as high as 208?mg g?1. Moreover the ideal adsorbed solution theory (IAST) prediction exhibited exceptionally high adsorption selectivity for CO2/CH4 in an equimolar mixture at 298?K and 1 bar (Sads = 27) which is significantly higher than that of some porous materials in the similar condition. PMID:25026895

Wang, Wenjing; Yuan, Daqiang

2014-01-01

167

Synthesis of three-dimensionally ordered macro-/mesoporous Pt with high electrocatalytic activity by a dual-templating approach  

NASA Astrophysics Data System (ADS)

Three dimensionally ordered macro-/mesoporous (3DOM/m) Pt catalysts are fabricated by chemical reduction employing a dual-templating synthesis approach combining both colloidal crystal (opal) templating (hard-templating) and lyotropic liquid crystal templating (soft-templating) techniques. The macropore walls of the prepared 3DOM/m Pt exhibit a uniform mesoporous structure composed of polycrystalline Pt nanoparticles. Both the size of the mesopores and Pt nanocrystallites are in the range of 3-5 nm. The 3DOM/m Pt catalyst shows a larger electrochemically active surface area (ECSA), and higher catalytic activity as well as better poisoning tolerance for methanol oxidation reaction (MOR) than the commercial Pt black catalyst.

Zhang, Chengwei; Yang, Hui; Sun, Tingting; Shan, Nannan; Chen, Jianfeng; Xu, Lianbin; Yan, Yushan

2014-01-01

168

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

169

Enhanced photocatalytic CO?-reduction activity of electrospun mesoporous TiO? nanofibers by solvothermal treatment.  

PubMed

Photocatalytic reduction of CO2 into renewable hydrocarbon fuels using semiconductor photocatalysts is considered as a potential solution to the energy deficiency and greenhouse effect. In this work, mesoporous TiO2 nanofibers with high specific surface areas and abundant surface hydroxyl groups are prepared using an electrospinning strategy combined with a subsequent calcination process, followed by a solvothermal treatment. The solvothermally treated mesoporous TiO2 nanofibers exhibit excellent photocatalytic performance on CO2 reduction into hydrocarbon fuels. The significantly improved photocatalytic activity can be attributed to the enhanced CO2 adsorption capacity and the improved charge separation after solvothermal treatment. The highest activity is achieved for the sample with a 2-h solvothermal treatment, showing 6- and 25-fold higher CH4 production rate than those of TiO2 nanofibers without solvothermal treatment and P25, respectively. This work may also provide a prototype for studying the effect of solvothermal treatment on the structure and photocatalytic activity of semiconductor photocatalysts. PMID:24809306

Fu, Junwei; Cao, Shaowen; Yu, Jiaguo; Low, Jingxiang; Lei, Yongpeng

2014-06-28

170

Ordered mesoporous mixed metal oxides: remarkable effect of pore size on catalytic activity.  

PubMed

We report the synthesis of ordered mesoporous NiAl mixed metal oxides (MMOs) from NiAl-layered double hydroxides (LDHs) through a soft template method using pluronic-F127 as the structure-directing agent. Ordered mesopores were obtained by the thermal decomposition of as-synthesized LDHs at different temperatures. The effects of the pluronic-F127 amount and the calcination temperature on the pore size distribution of the MMO were investigated. NiAl MMOs exhibited excellent catalytic activity in the Knoevenagel condensation of benzaldehyde with acidic methylene group-containing malononitrile. Finally, the dependence of the catalytic activity on the surface properties of NiAl MMOs was investigated. The pore diameter and the pore volume of NiAl MMOs were well correlated with the performance of the catalysts. MMO obtained from the calcination of NiAl-F127(3%)LDH at 750 °C for 5 h gave the highest conversion (>99%) in the Knoevenagel condensation in 30 min. The optimum pore diameter for the model reaction described here was 7.7 nm, which gave rise to more than 99% conversion with 100% selectivity. Ethanol gave the best conversion at 60 °C. The regenerated catalyst showed 93.0 and 89.0% of the initial catalytic activity after the first and the second regeneration cycles, respectively. PMID:24956493

Pahalagedara, Madhavi N; Pahalagedara, Lakshitha R; Kuo, Chung-Hao; Dharmarathna, Saminda; Suib, Steven L

2014-07-15

171

Nanocasting of carbon films with interdigitated bimodal three-dimensionally ordered mesopores by template-replica coassembly.  

PubMed

Carbon films with interdigitated bimodal three-dimensionally ordered mesoporosity (ib3DOm) are realized by a scalable nanoreplication process that removes the common need plaguing hard-templating strategies for multistep prefabrication of porous sacrificial templates. Specifically, evaporation-induced convective codeposition of size-tunable (ca. 20-50 nm) silica nanoparticles with a surrogate molecular carbon precursor (glucose), followed by carbonization and template etching, leads to remarkably ordered, crack-free mesoporous carbon films of tunable thickness (ca. 100-1000 nm) and pore size. Association of the molecular carbon precursor with the assembling pore forming particles is found to transition the system among three distinct film morphologies (collapsed, ib3DOm C, disordered), thereby establishing a pseudophase behavior controlled by silica solids content and incipient glucose concentration. Namely, a parametric window wherein ib3DOm C films can be realized is identified, with a diffuse lower phase boundary associated with collapsing carbon films, and a more distinct order-to-disorder transition encountered at higher glucose concentrations. Mechanistic insight suggests that glucose association with the lysine-silica nanoparticle surface modulates the lattice spacing, d, of the periodically ordered mesopores in the coassembled films, with the onset of the order-to-disorder transition occurring at a critical normalized lattice spacing, dc/D ? 1.16. This appears to apply across the phase space associated with D = 50 nm silica particles and to translate among other phase spaces associated with smaller particles (e.g., 30 nm). We briefly demonstrate the robustness of the codeposition process for realizing ib3DOm C films on rough FTO glass substrates and show that, in this form, these materials hold potential as low-cost alternatives to costly platinum electrodes for dye-sensitized solar cells. PMID:25248486

Tian, Zheng; Snyder, Mark A

2014-10-21

172

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

PubMed

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

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

2014-06-01

173

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

2012-07-01

174

GRANULAR ACTIVATED CARBON INSTALLATIONS  

EPA Science Inventory

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

175

Pore size engineering in fluorinated surfactant templated mesoporous silica powders through supercritical carbon dioxide processing  

Microsoft Academic Search

Pore expansion of fluorinated surfactant templated mesoporous silica powders is demonstrated as a function of pressurized CO2 processing conditions. Mesoporous silica powder is synthesized by sol–gel reaction induced precipitation in a base-catalyzed medium using 1-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-octyl)-pyridinium chloride (HFOPC) as a template and, immediately after filtration, the precipitated material is processed in gaseous and supercritical CO2 (88–344bar, 45°C) for 48h. Characterization of

Kaustav Ghosh; Sarah Bashadi; Hans-Joachim Lehmler; Stephen E. Rankin; Barbara L. Knutson

2008-01-01

176

Amperometric catechol biosensor based on laccase immobilized on nitrogen-doped ordered mesoporous carbon (N-OMC)/PVA matrix  

NASA Astrophysics Data System (ADS)

A functionalized nitrogen-containing ordered mesoporous carbon (N-OMC), which shows good electrical properties, was synthesized by the carbonization of polyaniline inside a SBA-15 mesoporous silica template. Based on this, through entrapping laccase onto the N-OMC/polyvinyl alcohol (PVA) film a facilely fabricated amperometric biosensor was developed. Laccase from Trametes versicolor was assembled on a composite film of a N-OMC/PVA modified Au electrode and the electrochemical behavior was investigated. The results indicated that the N-OMC modified electrode exhibits electrical properties towards catechol. The optimum experimental conditions of a biosensor for the detection of catechol were studied in detail. Under the optimal conditions, the sensitivity of the biosensor was 0.29 A*M-1 with a detection limit of 0.31 ?M and a linear detection range from 0.39 ?M to 8.98 ?M for catechol. The calibration curve followed the Michaelis-Menten kinetics and the apparent Michaelis-Menten \\left( K_{M}^{app} \\right) was 6.28 ?M. This work demonstrated that the N-OMC/PVA composite provides a suitable support for laccase immobilization and the construction of a biosensor.

Guo, Meiqing; Wang, Hefeng; Huang, Di; Han, Zhijun; Li, Qiang; Wang, Xiaojun; Chen, Jing

2014-06-01

177

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

178

Elimination of Extraneous Irreversible Capacity in Mesoporous Tin Phosphate Anode by Amorphous Carbon Coating  

E-print Network

. Although tin phosphate is a promising anode material for Li-secondary battery, a larger volume change from ability.14 Recently Kim et al. reported that mesoporous/crystalline tin phosphate composite exhibited consist- ing of B­P­O­Li composites.17,18 Typically, irreversible capacity loss was approximately between

Cho, Jaephil

179

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

180

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

2012-12-01

181

Influences of urea–glycerol mixtures as mixed mesopore-controlling agents on tailoring physicochemical properties and photocatalytic H{sub 2} production activity of sol–gel-derived mesoporous-assembled TiO{sub 2} nanocrystals  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Mesoporous-assembled TiO{sub 2} nanocrystals were synthesized by modified sol–gel process. ? Urea–glycerol mixtures were applied as mixed mesopore-controlling agents. ? Urea and glycerol contents affected physicochemical properties of synthesized TiO{sub 2}. ? Photocatalytic H{sub 2} production activity also depended on urea and glycerol contents. ? 75 mol% urea and 25 mol% glycerol yielded the most photocatalytically active TiO{sub 2}. -- Abstract: In this work, the mesoporous-assembled TiO{sub 2} nanocrystal photocatalysts were successfully synthesized by a sol–gel process with the aid of urea–glycerol mixtures used as mixed mesopore-controlling agents. The photocatalytic activity of the synthesized mesoporous-assembled TiO{sub 2} nanocrystal photocatalysts was investigated for hydrogen production from the water splitting reaction using methanol as a hole scavenger under UV light irradiation. The synthesized TiO{sub 2} nanocrystal photocatalysts were systematically characterized by TG–DTA, N{sub 2} adsorption–desorption, SEM, high resolution TEM, and XRD analyses. The characterization results showed that the well-controlled contents of urea and glycerol in a urea–glycerol mixture at 75 mol% urea and 25 mol% glycerol resulted in not only the most highly porous network (i.e. the highest specific surface area and total pore volume, and the smallest mean mesopore diameter), but also the smallest crystallite size of the synthesized TiO{sub 2} nanocrystal photocatalyst. The photocatalytic reaction results, hence, revealed a much superior photocatalytic hydrogen production activity of the mesoporous-assembled TiO{sub 2} nanocrystal synthesized with 75 mol% urea and 25 mol% glycerol to the other synthesized TiO{sub 2} nanocrystals, also being much higher than those of the commercially available P-25 TiO{sub 2} and ST-01 TiO{sub 2} powders.

Sreethawong, Thammanoon, E-mail: sreethawongt@imre.a-star.edu.sg [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore)] [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore); Ngamsinlapasathian, Supachai, E-mail: wonone@hotmail.com [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)] [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan); Yoshikawa, Susumu [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)] [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)

2013-01-15

182

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

2013-01-01

183

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. PMID:24084754

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

2013-01-01

184

Importance of structural and chemical heterogeneity of activated carbon surfaces for adsorption of dibenzothiophene  

SciTech Connect

The performance of various activated carbons obtained from different carbon precursors (i.e., plastic waste, coal, and wood) as adsorbents for the desulfurization of liquid hydrocarbon fuels was evaluated. To increase surface heterogeneity, the carbon surface was modified by oxidation with ammonium persulfate. The results showed the importance of activated carbon pore sizes and surface chemistry for the adsorption of dibenzothiophene (DBT) from liquid phase. Adsorption of DBT on activated carbons is governed by two types of contributions: physical and chemical interactions. The former include dispersive interactions in the microporous network of the carbons. While the volume of micropores governs the amount physisorbed, mesopores control the kinetics of the process. On the other hand, introduction of surface functional groups enhances the performance of the activated carbons as a result of specific interactions between the acidic centers of the carbon and the basic structure of DBT molecule as well as sulfur-sulfur interactions.

Ania, C.O.; Bandosz, T.J. [CUNY City College, New York, NY (United States). Dept. of Chemistry

2005-08-16

185

Sulfur-functionalized mesoporous carbons as sulfur hosts in Li-S batteries: increasing the affinity of polysulfide intermediates to enhance performance.  

PubMed

The Li-S system offers a tantalizing battery for electric vehicles and renewable energy storage due to its high theoretical capacity of 1675 mAh g(-1) and its employment of abundant and available materials. One major challenge in this system stems from the formation of soluble polysulfides during the reduction of S8, the active cathode material, during discharge. The ability to deploy this system hinges on the ability to control the behavior of these polysulfides by containing them in the cathode and allowing for further redox. Here, we exploit the high surface areas and good electrical conductivity of mesoporous carbons (MC) to achieve high sulfur utilization while functionalizing the MC with sulfur (S-MC) in order to modify the surface chemistry and attract polysulfides to the carbon material. S-MC materials show enhanced capacity and cyclability trending as a function of sulfur functionality, specifically a 50% enhancement in discharge capacity is observed at high cycles (60-100 cycles). Impedance spectroscopy suggests that the S-MC materials exhibit a lower charge-transfer resistance compared with MC materials which allows for more efficient electrochemistry with species in solution at the cathode. Isothermal titration calorimetry shows that the change in surface chemistry from unfunctionalized to S-functionalized carbons results in an increased affinity of the polysulfide intermediates for the S-MC materials, which is the likely cause for enhanced cyclability. PMID:24524220

See, Kimberly A; Jun, Young-Si; Gerbec, Jeffrey A; Sprafke, Johannes K; Wudl, Fred; Stucky, Galen D; Seshadri, Ram

2014-07-23

186

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

2011-05-13

187

Thermally decomposed mesoporous Nickel Iron hydrotalcite: An active solid-base catalyst for solvent-free Knoevenagel condensation.  

PubMed

Thermal decomposition of co-precipitated NiFeHT materials led to the formation a mesoporous NiFeHT catalyst and we have demonstrated here its active role as solid and active catalyst for the Knoevenagel condensation reaction of various aldehydes with active methylene compounds (RCH2CN, where RCN or CO2Et). High product yields are obtained at moderate temperature under solvent-free conditions and the catalyst can be easily separated from the reaction mixture, simply by filtration and reused several times without a significant loss of its activity. Since these mesoporous metal oxides derived from the NiFe hydrotalcites, their basicity mediated abstraction of the acidic protons from the active methylene compounds was responsible for their catalytic activity under solvent-free conditions. PMID:25490562

Dumbre, Deepa K; Mozammel, Tibra; Selvakannan, Pr; Hamid, Sharifah Bee Abdul; Choudhary, Vasant R; Bhargava, Suresh K

2015-03-01

188

Carboxylated mesoporous carbon microparticles as new approach to improve the oral bioavailability of poorly water-soluble carvedilol.  

PubMed

The main objective of this study was to develop carboxylated ordered mesoporous carbon microparticles (c-MCMs) loaded with a poorly water-soluble drug, intended to be orally administered, able to enhance the drug loading capacity and improve the oral bioavailability. A model drug, carvedilol (CAR), was loaded onto c-MCMs via a procedure involving a combination of adsorption equilibrium and solvent evaporation. The physicochemical properties of the drug-loaded composites were systematically studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and HPLC. It was found that c-MCM has a high drug loading level up to 41.6%, and higher than that of the mesoporous silica template. Incorporation of CAR in both drug carriers enhanced the solubility and dissolution rate of the drug, compared to the pure crystalline drug. After loading CAR into c-MCMs, its oral bioavailability was compared with the marketed product in dogs. The results showed that the bioavailability of CAR was improved 179.3% compared with that of the commercial product when c-MCM was used as the drug carrier. We believe that the present study will help in the design of oral drug delivery systems for enhanced oral bioavailability of poorly water-soluble drugs. PMID:23850816

Zhang, Yanzhuo; Zhi, Zhizhuang; Li, Xue; Gao, Jian; Song, Yaling

2013-09-15

189

Synthesis of ruthenium oxide coated ordered mesoporous carbon nanofiber arrays as a catalyst for lithium oxygen battery  

NASA Astrophysics Data System (ADS)

Li-O2 batteries with super-high theoretical energy density are attracting extensive attention. However, the sluggish oxygen reduction/evolution reaction, the huge volume change from O2/Li2O2 conversion and the undesired electrolyte decomposition in cathode limit their performance. Herein we show design and synthesis of RuO2-coated ordered mesoporous carbon nanofiber arrays by using a natural crab shell template as a catalyst for Li-O2 battery, exhibiting several advantage features. First, the ordered mesopores in nanofibers facilitate electrolyte penetration and electron/ion transfer. In addition, the macro-sized voids between the nanofibers provide efficient buffer space for O2/Li2O2 accommodation and improve O2 diffusion. Furthermore, the uniform RuO2-coating layer alleviates undesired electrolyte decomposition and enhances the surface electronic conductivity. As a result, the battery displays high performance, including high capacity (20600 mAh g-1 at a current density of 100 mA g-1), high rate (9750 mAh g-1 at a current density of 1000 mA g-1) and long-life (300 cycles at a fixed capacity of 1000 mAh g-1).

Guo, Ziyang; Zhou, Dandan; Liu, Haijing; Dong, Xiaoli; Yuan, Shouyi; Yu, Aishui; Wang, Yonggang; Xia, Yongyao

2015-02-01

190

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

191

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

192

Studies of adsorption equilibria and kinetics in the systems: Aqueous solution of dyes-mesoporous carbons  

NASA Astrophysics Data System (ADS)

Two carbonaceous materials were synthesized by using the method of impregnation of mesoporous silicas obtained by applying the Pluronic copolymers as pore-creating agents. The isotherms of adsorption of methylene blue and methyl orange from aqueous solutions were measured by the static method. The profiles of adsorbate concentration change in time were obtained from the UV-vis spectra. The adsorption isotherms and kinetic dependence were discussed in the terms of theory of adsorption on heterogeneous surfaces.

Derylo-Marczewska, A.; Marczewski, A. W.; Winter, Sz.; Sternik, D.

2010-06-01

193

Growth of carbon nanofibers on activated carbon fiber fabrics  

Microsoft Academic Search

Activated carbon fiber fabrics, an excellent adsorbent, were used as catalyst supports to grow carbon nanofibers. Because of the microporous structure of the activated carbon fibers, the catalysts could be distributed uniformly on the carbon surface. Based on this concept, the carbon nanofibers can be grown directly on the activated carbon fiber fabrics. We demonstrate that carbon nanofibers with a

Shinn-Shyong Tzeng; Kai-Hsuan Hung; Tse-Hao Ko

2006-01-01

194

Comparison on pore development of activated carbon produced from palm shell and coconut shell.  

PubMed

A series of experiments were conducted to compare the pore development in palm-shell and coconut-shell-based activated carbons produced under identical experimental conditions. Carbonization and activation processes were carried out at 850 degrees C using a fluidized bed reactor. Within the range of burn-off studied, at any burn-off, the micropore and mesopore volumes created in palm-shell-based activated carbon were always higher than those of coconut-shell-based activated carbon. On macropore volume, for palm-shell-based activated carbon, the volume increased with increase in burn-off up to 30% and then decreased. However, for coconut-shell-based activated carbon, the change in macropore volume with burn-off was almost negligible but the absolute macropore volume decreased with burn-off. PMID:14987722

Daud, Wan Mohd Ashri Wan; Ali, Wan Shabuddin Wan

2004-05-01

195

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

196

An evaporation-induced tri-consistent assembly route towards nitrogen-doped carbon microfibers with ordered mesopores for high performance supercapacitors.  

PubMed

Nitrogen-doped mesoporous carbon microfibers (NMCMFs) were prepared via an evaporation-induced tri-consistent assembly of a triblock copolymer, resols and prehydrolyzed tetraethoxy silane on natural silk followed by pyrolysis. The resultant NMCMFs inherit the advantages of both order mesoporous carbons (OMCs) and carbon microfibers (CMFs), such as uniform meso-channels, high surface area, high nitrogen content, excellent electronic conductivity as well as good flexibility. Owing to the well-designed nanostructure and the synergistic effects of the strongly coupled components, the binder-free electrodes based on NMCMFs exhibit enhanced capacity (189 F g(-1) at 5 mV s(-1)), excellent rate capability (107 F g(-1) at 100 mV s(-1)) and durability (maintained over 96% of the initial capacitance after 10?000 cycles) in electric double-layer capacitors, outperforming those of OMCs and CMFs derived from pristine silk. PMID:25588922

Liu, Ruili; Pan, Lixia; Wan, Li; Wu, Dongqing

2015-01-28

197

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

198

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

199

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

2014-06-01

200

Preparation of activated carbons from cherry stones by activation with potassium hydroxide  

NASA Astrophysics Data System (ADS)

Using cherry stones, the preparation of activated carbon has been undertaken in the present study by chemical activation with potassium hydroxide. A series of KOH-activated products was prepared by varying the carbonisation temperature in the 400 900 °C range. Such products were characterised texturally by gas adsorption (N2, -196 °C), mercury porosimetry, and helium and mercury density measurements. FT-IR spectroscopy was also applied. The carbons prepared as a rule are microporous and macroporous solids. The degree of development of surface area and porosity increases with increasing carbonisation temperature. For the carbon heated at 900 °C the specific surface area (BET) is 1624 m2 g-1, the micropore volume is 0.67 cm3 g-1, the mesopore volume is 0.28 cm3 g-1, and the macropore volume is 1.84 cm3 g-1.

Olivares-Marín, M.; Fernández-González, C.; Macías-García, A.; Gómez-Serrano, V.

2006-06-01

201

Peroxidase-like activity of mesoporous silica encapsulated Pt nanoparticle and its application in colorimetric immunoassay.  

PubMed

Nanomaterial-based artificial enzymes have received great attention in recent year due to their potential application in immunoassay techniques. However, such potential is usually limited by poor dispersion stability or low catalytic activity induced by the capping agent essentially required in the synthesis. In an attempt to address these challenges, here, we studied the novel Pt nanoparticles (NPs) based peroxidase-like mimic by encapsulating Pt NP in mesoporous silica (Pt@mSiO2 NPs). Compared with other nanomaterial-based artificial enzymes, the obtained Pt@mSiO2 NPs not only exhibit high peroxidase-like activity but also have good dispersion stability in buffer saline solution when grafted with spacer PEG. Results show that when the thickness of silica shell is about 9nm the resulting Pt@mSiO2 NPs exhibit the catalytic activity similar to that of Pt NPs, which is approximately 26 times higher than that of Fe3O4 NPs (in terms of Kcat for H2O2). Due to the protection of silica shell, the subsequent surface modification with antibody has little effect on their catalytic activity. The analytical performance of this system in detecting hCG shows that after 5min incubation the limit of detection can reach 10ngmL(-1) and dynamic linear working range is 5-200ngmL(-1). Our findings pave the way for design and development of novel artificial enzyme labeling. PMID:25682428

Wang, Zhifei; Yang, Xia; Yang, Jingjing; Jiang, Yanyun; He, Nongyue

2015-03-01

202

A general chelate-assisted co-assembly to metallic nanoparticles-incorporated ordered mesoporous carbon catalysts for Fischer-Tropsch synthesis.  

PubMed

The organization of different nano objects with tunable sizes, morphologies, and functions into integrated nanostructures is critical to the development of novel nanosystems that display high performances in sensing, catalysis, and so on. Herein, using acetylacetone as a chelating agent, phenolic resol as a carbon source, metal nitrates as metal sources, and amphiphilic copolymers as a template, we demonstrate a chelate-assisted multicomponent coassembly method to synthesize ordered mesoporous carbon with uniform metal-containing nanoparticles. The obtained nanocomposites have a 2-D hexagonally arranged pore structure, uniform pore size (~4.0 nm), high surface area (~500 m(2)/g), moderate pore volume (~0.30 cm(3)/g), uniform and highly dispersed Fe(2)O(3) nanoparticles, and constant Fe(2)O(3) contents around 10 wt %. By adjusting acetylacetone amount, the size of Fe(2)O(3) nanoparticles is readily tunable from 8.3 to 22.1 nm. More importantly, it is found that the metal-containing nanoparticles are partially embedded in the carbon framework with the remaining part exposed in the mesopore channels. This unique semiexposure structure not only provides an excellent confinement effect and exposed surface for catalysis but also helps to tightly trap the nanoparticles and prevent aggregating during catalysis. Fischer-Tropsch synthesis results show that as the size of iron nanoparticles decreases, the mesoporous Fe-carbon nanocomposites exhibit significantly improved catalytic performances with C(5+) selectivity up to 68%, much better than any reported promoter-free Fe-based catalysts due to the unique semiexposure morphology of metal-containing nanoparticles confined in the mesoporous carbon matrix. PMID:23020275

Sun, Zhenkun; Sun, Bo; Qiao, Minghua; Wei, Jing; Yue, Qin; Wang, Chun; Deng, Yonghui; Kaliaguine, Serge; Zhao, Dongyuan

2012-10-24

203

Fabrication of thermally stable and active bimetallic Au-Ag nanoparticles stabilized on inner wall of mesoporous silica shell.  

PubMed

A general method has been developed for the fabrication of highly dispersed and thermally stable bimetallic Au-Ag nanoparticles (NPs) stabilized on the inner wall of a mesoporous silica shell. In our approach, gold particles were formed in the first step on carbon spheres decorated with Sn(2+) cations. Upon Ag(+) adsorption and reduction by l-ascorbic acid in the second step, specific nanoparticles with a gold-silver alloy core and a silver nanoshell have been formed. Important evidence of the core-shell configurations of the bimetallic Au-Ag nanoparticles were clearly characterized by UV-vis, TEM and HAADF-STEM observations combined with elemental mapping and line scans. The mesoporous silica outer shell was obtained through the hydrolysis and condensation of the precursors tetraethoxysilane (TEOS) in a basic condition and cetyltrimethylammonium bromide (CTAB) as a structure-directing agent. On this basis, the nanoreactors were fabricated after calcination, which further serves as a nanoreactor for the reduction of p-nitrophenol. Furthermore, such particles have been found to be thermally stable and their sizes remain substantially unchanged even upon calcination in air at 500 °C and a reduction treatment in H2. Potentially, the method can be developed into a general approach to synthesize other highly dispersed and thermally stable bimetallic nanoparticles stabilized on the inner wall of a mesoporous silica shell. PMID:23925801

Chen, Yu; Wang, Qihua; Wang, Tingmei

2013-10-14

204

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. PMID:20445747

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

2010-01-01

205

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

206

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

207

Hierarchical mesoporous yolk-shell structured carbonaceous nanospheres for high performance electrochemical capacitive energy storage.  

PubMed

Hierarchical mesoporous yolk-shell structured carbon nanospheres (YSCNs) with an ordered mesoporous carbon core and a microporous carbon shell show excellent electrochemical performance with a maximal specific capacitance of 159 F g(-1). PMID:25563395

Yang, Tianyu; Zhou, Ruifeng; Wang, Da-Wei; Jiang, San Ping; Yamauchi, Yusuke; Qiao, Shi Zhang; Monteiro, Michael J; Liu, Jian

2015-01-29

208

Complexity of ammonia interactions on activated carbons modified with V 2O 5  

Microsoft Academic Search

A micro\\/mesoporous wood-based activated carbon was modified with different loadings of vanadium pentoxide via incipient impregnation with ammonium vanadate solution followed by heating in nitrogen at 500?°C. The materials were used as adsorbents for ammonia. Both adsorption and desorption curves were recorded. The initial and exhausted samples were characterized by Fourier transform infrared spectroscopy (FTIR), potentiometric titration, thermal analysis and

Camille Petit; Teresa J. Bandosz

2008-01-01

209

Comparison of the surface features of two wood-based activated carbons  

SciTech Connect

The surface features of two carbons of wood origin were compared. One sample was manufactured using phosphoric acid activation and the other using potassium hydroxide activation. To check the susceptibility to oxidation and the stability of the porous structure, the samples were oxidized with ammonium persulfate. Structural properties of carbons and their oxidized counterparts were determined using sorption of nitrogen. Surface acidity was evaluated using Boehm titration, potentiometric titration, inverse gas chromatography, and diffuse reflectance FTIR. It was demonstrated that, despite the same wood origin, the carbons significantly differ in their pore structure and surface chemistry. The carbon obtained using KOH activation is homogeneously microporous with high surface area around 2,300 m{sup 2}/g (BET). On the other hand, the carbon manufactured using phosphoric acid contains a high volume of mesopores and its surface area is significantly lower. The carbons also differ in their surface chemistry and susceptibility to oxidation.

Salame, I.I.; Bandosz, T.J.

2000-02-01

210

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

1999-02-01

211

Simple fabrication of N-doped mesoporous TiO2 nanorods with the enhanced visible light photocatalytic activity  

PubMed Central

N-doped mesoporous TiO2 nanorods were fabricated by a modified and facile sol–gel approach without any templates. Ammonium nitrate was used as a raw source of N dopants, which could produce a lot of gasses such as N2, NO2, and H2O in the process of heating samples. These gasses were proved to be vitally important to form the special mesoporous structure. The samples were characterized by the powder X-ray diffraction, X-ray photoelectron spectrometer, nitrogen adsorption isotherms, scanning electron microscopy, transmission electron microscopy, and UV-visible absorption spectra. The average length and the cross section diameter of the as-prepared samples were ca. 1.5 ?m and ca. 80 nm, respectively. The photocatalytic activity was evaluated by photodegradation of methylene blue (MB) in aqueous solution. The N-doped mesoporous TiO2 nanorods showed an excellent photocatalytic activity, which may be attributed to the enlarged surface area (106.4 m2 g-1) and the narrowed band gap (2.05 eV). Besides, the rod-like photocatalyst was found to be easy to recycle. PMID:24428848

2014-01-01

212

Nanogold/mesoporous carbon foam-mediated silver enhancement for graphene-enhanced electrochemical immunosensing of carcinoembryonic antigen.  

PubMed

Nanogold functionalized mesoporous carbon foam (Au/MCF) coupling with a signal amplification by C-Au synergistic silver enhancement was designed for sensitive electrochemical immunosensing of biomarker. The Au/MCF was prepared by in situ growth of nanogold on carboxylated MCF and used as a tracing tag to label signal antibody via the inherent interaction between protein and nanogold. The immunosensor was prepared by covalently immobilizing capture antibody on an electrochemically reduced graphene oxide/chitosan film modified glassy carbon electrode. Through a sandwich-type immunoreaction, Au/MCF tags were captured on the immunoconjugates to induce a silver deposition process. The electrochemical stripping signal of the deposited silver was used to monitor the immunoreaction. The Au/MCF-mediated silver enhancement along with the graphene-promoted electron transfer led to high detection sensitivity of carcinoembryonic antigen. Under optimal conditions, the proposed immunoassay method showed wide linear range from 0.05 pg mL(-1) to 1 ng mL(-1) and a detection limit down to 0.024 pg mL(-1). The newly designed amplification strategy holds great potential for ultrasensitive electrochemical biosensing of other analytes. PMID:24041661

Lin, Dajie; Wu, Jie; Ju, Huangxian; Yan, Feng

2014-02-15

213

Amplified and selective detection of manganese peroxidase genes based on enzyme-scaffolded-gold nanoclusters and mesoporous carbon nitride.  

PubMed

This work has demonstrated an amplified and selective detection platform using enzyme-scaffolded-gold nanoclusters as signal label, coupling with mesoporous carbon nitride (MCN) and gold nanoparticles (GNPs) modified glassy carbon electrode (GCE). Streptavidin-horseradish peroxidase (SA-HRP) has been integrated with gold nanoclusters (GNCs) as scaffold using a simple, fast and non-toxic method. The mechanisms of enzymatic amplification, redox cycling and signal amplification by this biosensor were discussed in detail. GNCs might perform important roles as electrocatalyst as well as electron transducer in these processes. The concentrations of reagents and the reaction times of these reagents were optimized to improve the analytical performances. Under the optimized condition, the signal response to enzyme-scaffolded-gold nanoclusters catalyzed reaction was linearly related to the natural logarithm of the target nucleic acid concentration in the range from 10(-17)M to 10(-9)M with a correlation coefficient of 0.9946, and the detection limit was 8.0×10(-18)M (S/N=3). Besides, synthesized oligonucleotide as well as Phanerochaete chrysosporium MnP fragments amplified using polymerase chain reaction and digested by restriction endonucleases were tested. Furthermore, this biosensor exhibited good precision, stability, sensitivity, and selectivity, and discriminated satisfactorily against mismatched nucleic acid samples of similar lengths. PMID:25461185

Zhou, Yaoyu; Tang, Lin; Zeng, Guangming; Chen, Jun; Wang, Jiajia; Fan, Changzheng; Yang, Guide; Zhang, Yi; Xie, Xia

2014-10-31

214

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

PubMed

The objective of this study was to evaluate the adsorption capacity for toluene and SO2 of low cost activated carbons prepared from sewage sludge by chemical activation at different impregnation ratios. Samples were characterized by proximate and ultimate analyses, thermogravimetry, infrared spectroscopy and N2 adsorption. Because of the low carbon content of the raw material, the development of porosity in the activated carbons was mainly of a mesoporous nature, with surface areas lower than 300 m(2)/g. The study of gas-phase applications for activated carbons from sewage sludge was carried out using both an organic and an inorganic compound in order to screen for possible applications. Toluene adsorption capacity at saturation was around 280 mg/g, which is a good level of performance given the high ash content of the activated carbons. However, dynamic experiments at low toluene concentration presented diffusion problems resulting from low porosity development. SO2 adsorption capacity is associated with average micropore size, which can be controlled by the impregnation ratio used to prepare the activated carbons. PMID:24747937

Boualem, T; Debab, A; Martínez de Yuso, A; Izquierdo, M T

2014-07-01

215

Preparation of Catalytic Nanoparticles in Mesoporous Silica Film for Oriented Growth of Single-Walled Carbon Nanotubes  

E-print Network

unique properties and remarkable potentials as an advanced material. In order to utilize SWNTs widelyPreparation of Catalytic Nanoparticles in Mesoporous Silica Film for Oriented Growth of Single mesoporous silica film as a guide of the growth for SWNTs. For the orientation, the catalyst for the growth

Maruyama, Shigeo

216

Probing Mechanisms for Enzymatic Activity Enhancement of Organophosphorus Hydrolase in Functionalized Mesoporous Silica  

SciTech Connect

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

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

2009-12-25

217

Application of low-voltage field-emission SEM to the study of internal pore structures of activated carbon  

SciTech Connect

Activated carbon has interesting and useful properties for industrial applications. It has been used extensively in purification, separation, chemical recovery and catalysis. To achieve a predictable performance of activated carbon materials, it is necessary to develop a comprehensive understanding of the pore structure including pore size, pore shape, and pore surface chemistry. Macropores (> 50 nm), mesopores (2-50 nm) and micropores (< 2 nm) generally coexist in activated carbon. It is thus desirable to synthesize activated carbon with controlled pore structures to optimize its performance. We previously reported the characterization of the surface pore structure of activated carbon by field emission SEM (FESEM) and the examination of the internal pore structure by HAADF/HRTEM techniques. However, both HAADF and HRTEM techniques give only limited information about the carbon pore structure. We report here some preliminary observation of the internal pore structure of activated carbon by high resolution low voltage FESEM technique.

Liu, J.; Ornberg, R.L. [Monsanto Corp. Research, St. Louis, MO (United States)

1996-12-31

218

Novel mesoporous graphite carbon nitride/BiOI heterojunction for enhancing photocatalytic performance under visible-light irradiation.  

PubMed

A novel organic-inorganic three-dimensional (3D) mesoporous graphite carbon nitride/BiOI (MCN/BiOI) heterojunction photocatalyst with excellent visible-light-driven photocatalytic performance was synthesized by a facile solvothermal method and used for degradation of bisphenol A (BPA) in water. After hybridization with MCN, a heterojunction was formed and the photogenerated carriers could be effectively separated by the internal electric field built at the heterojunction interface. The photocatalytic and photoelectrochemical performance of BiOI were improved and much higher than pure BiOI and MCN. The best photocatalytic performance was achieved with MCN proportion of 10%, and the kobs was approximately 1.6 times of pure BiOI and 3.4 times of MCN under simulated solar light irradiation, respectively. The photocurrent intensity generated by 10%-MCN/BiOI electrode was about 1.5 and 2.0 times of those induced by BiOI and MCN under visible-light irradiation, respectively. The superoxide radical species were predominant in the reaction system. PMID:24635982

Chang, Chun; Zhu, Lingyan; Wang, Shanfeng; Chu, Xiaolong; Yue, Longfei

2014-04-01

219

Rapid adsorption of 2,4-dichlorophenoxyacetic acid by iron oxide nanoparticles-doped carboxylic ordered mesoporous carbon.  

PubMed

The ordered mesoporous carbon composite functionalized with carboxylate groups and iron oxide nanoparticles (Fe/OMC) was successfully prepared and used to adsorb 2,4-dichlorophenoxyacetic acid (2,4-D) from wastewater. The resultant adsorbent possessed high degree of order, large specific surface area and pore volume, and good magnetic properties. The increase in initial pollutant concentration and contact time would make the adsorption capacity increase, but the pH and temperature are inversely proportional to 2,4-D uptake. The equilibrium of adsorption was reached within 120min, and the equilibrated adsorption capacity increased from 99.38 to 310.78mg/g with the increase of initial concentration of 2,4-D from 100 to 500mg/L. Notablely, the adsorption capacity reached 97% of the maximum within the first 5min. The kinetics and isotherm study showed that the pseudo-second-order kinetic and Langmuir isotherm models could well fit the adsorption data. These results indicate that Fe/OMC has a good potential for the rapid adsorption of 2,4-D and prevention of its further diffusion. PMID:25594883

Tang, Lin; Zhang, Sheng; Zeng, Guang-Ming; Zhang, Yi; Yang, Gui-De; Chen, Jun; Wang, Jing-Jing; Wang, Jia-Jia; Zhou, Yao-Yu; Deng, Yao-Cheng

2015-05-01

220

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

2011-07-01

221

Formation of Carbon Nanosheets via Simultaneous Activation and Catalytic Carbonization of Macroporous Anion-Exchange Resin for Supercapacitors Application.  

PubMed

Two-dimensional mesoporous carbon nanosheets (CNSs) have been prepared via simultaneous activation and catalytic carbonization route using macroporous anion-exchange resin (AER) as carbon precursor and ZnCl2 and FeCl3 as activating agent and catalyst, respectively. The iron catalyst in the skeleton of the AER may lead to carburization to form a sheetlike structure during the carbonization process. The obtained CNSs have a large number of mesopores, a maximum specific surface area of 1764.9 m(2) g(-1), and large pore volume of 1.38 cm(3) g(-1). As an electrode material for supercapacitors application, the CNSs electrode possesses a large specific capacitance of 283 F g(-1) at 0.5 A g(-1) and excellent rate capability (64% retention ratio even at 50 A g(-1)) in 6 mol L(-1) KOH. Furthermore, CNSs symmetric supercapacitor exhibits specific energies of 17.2 W h kg(-1) at a power density of 224 W kg(-1) operated in the voltage range of 0-1.8 V in 0.5 mol L(-1) Na2SO4 aqueous electrolyte, and outstanding cyclability (retains about 96% initial capacitance after 5000 cycles). PMID:25372656

Peng, Hui; Ma, Guofu; Sun, Kanjun; Mu, Jingjing; Zhang, Zhe; Lei, Ziqiang

2014-12-10

222

Mesoporous carbon microparticles as a novel fluorescent sensing platform for thrombin detection.  

PubMed

The present paper presents the novel use of MC microparticles (MCMPs) as a novel fluorescent sensing platform for thrombin detection. The MCMPs were prepared by a nanocasting method using mesoporous silica (MS) NPs as a hard template. The general concept used in this approach lies in the facts that the non-covalent adsorption of the dye-labeled TA on MCMP driven by ?-? stacking of DNA bases on MCMP leads to substantial quenching of dye fluorescence due to their very close proximity. However, the presence of target TB results in the change of TA conformation to quadruplex due to the quadruplex-TB complex formation. Because the binding between the complex and MCMP is not strong enough to guarantee the close proximity of dyes to MCMP surface, fluorescence quenching is suppressed. This sensing system has a low detection limit down to 0.25nM and exhibits excellent selectivity. We also demonstrate its application in human blood serum system. PMID:21440431

Zhang, Yingwei; Liu, Sen; Sun, Xuping

2011-05-15

223

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

PubMed

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

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

2014-10-15

224

Ultrasensitive electrochemical sensor for p-nitrophenyl organophosphates based on ordered mesoporous carbons at low potential without deoxygenization.  

PubMed

p-Nitrophenyl organophosphates (OPs) including paraoxon, parathion and methyl parathion, etc, are highly poisonous OPs, for which sensitive and rapid detection method is most needed. In this work, an ultrasensitive electrochemical sensor for the determination of p-nitrophenyl OPs was developed based on ordered mesoporous carbons (OMCs) modified glassy carbon electrode (GCE) (OMCs/GCE). The electrochemical behavior and reaction mechanism of p-nitrophenyl OPs at OMCs/GCE was elaborated by taking paraoxon as an example. Experimental conditions such as buffer pH, preconcentration potential and time were optimized. By using differential pulse voltammetry, the current response of the sensor at -0.085 V was linear with concentration within 0.01-1.00 ?M and 1.00-20 ?M paraoxon. Similar linear ranges of 0.015-0.5 ?M and 0.5-10 ?M were found for parathion, and 0.01-0.5 ?M and 0.5-10 ?M for methyl parathion. The low limits of detection were evaluated to be 1.9nM for paraoxon, 3.4 nM for parathion and 2.1 nM for methyl parathion (S/N=3). Common interfering species had no interference to the detection of p-nitrophenyl OPs. The sensor can be applicable to real samples measurement. Therefore, a simple, sensitive, reproducible and cost-effective electrochemical sensor was proposed for the fast direct determination of trace p-nitrophenyl OPs at low potential without deoxygenization. PMID:24725744

Zhang, Tingting; Zeng, Lingxing; Han, Lei; Li, Tie; Zheng, Cheng; Wei, Mingdeng; Liu, Aihua

2014-04-25

225

Synthesis and characterization of Zr4+, La3+ and Ce3+ doped mesoporous TiO2: evaluation of their photocatalytic activity.  

PubMed

Sol-gel method was used to synthesize Zr(4+), La(3+) and Ce(3+) doped mesoporous TiO(2) materials with different weight percentage (0.5, 1.0, 2.0 and 3.0 wt%) using triblock copolymer as the structure directing template in ethanol/water medium. Characterization revealed the isomorphic substitution of Zr(4+) ion into the lattice of TiO(2), and surface binding nature of La(3+) and Ce(3+) ions on mesoporous TiO(2). Microscopic examination confirmed the surface adsorption of foreign ion which could alter the particle morphology. The size of the particles was less than 20 nm. Photocatalytic activity of metal ions doped mesoporous TiO(2) was evaluated using aqueous alachlor as a model pollutant. It was found that 1 wt% Ce(3+) doped mesoporous TiO(2) exhibited higher activity than pure and other metal ions doped mesoporous TiO(2). The change of oxidation state of Ce(3+) is suggested to be the cause for enhanced photocatalytic activity. PMID:21237564

Kumaresan, L; Prabhu, A; Palanichamy, M; Arumugam, E; Murugesan, V

2011-02-28

226

Towards establishing structure–activity relationships for mesoporous silica in drug delivery applications  

Microsoft Academic Search

Mesoporous silicas are currently widely studied carrier matrices in drug delivery applications. Surface functionalization of the silica is often employed in order to enhance the interaction between the drug and the support. However, in many cases the effectiveness of the introduced surface functions is much lower than what could be expected, and the release rate from surface functionalized silica is

Jessica M. Rosenholm; Mika Lindén

2008-01-01

227

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

SciTech Connect

Partly ordered mesoporous titania films with anatase crystallites incorporated into the pore walls were prepared at low temperature by spin-coating a microemulsion-based reaction solution. The effect of relative humidity employed during aging of the prepared films was studied using SEM, TEM, and grazing incidence small angle X-ray scattering to evaluate the mesoscopic order, porosity, and crystallinity of the films. The study shows unambiguously that crystal growth occurs mainly during storage of the films and proceeds at room temperature largely depending on relative humidity. Porosity, pore size, mesoscopic order, crystallinity, and photocatalytic activity of the films increased with relative humidity up to an optimum around 75%.

Elgh, Björn; Yuan, Ning; Palmqvist, Anders E. C. [Applied Surface Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology, SE 412 96 Göteborg (Sweden); Cho, Hae Sung; Terasaki, Osamu [Graduate School of EEWS (WCU), KAIST, Daejeon 305-701 (Korea, Republic of); Magerl, David; Philipp, Martine; Müller-Buschbaum, Peter [Lehrstuhl für Funktionelle Materialien, Physik-Department, Technische Universität München, 85748 Garching (Germany); Roth, Stephan V. [DESY, Notkestrasse 85, 22603 Hamburg (Germany); Yoon, Kyung Byung [Department of Chemistry, Sogang University, Seoul 121-742 (Korea, Republic of)

2014-11-01

228

Experimental design to optimize preparation of activated carbons for use in water treatment.  

PubMed

A series of seven activated carbons was obtained for use in drinking water treatments by steam-activation of olive-waste cakes. This raw material is an abundant and cheap waste byproduct of oil production, making these activated carbons economically feasible. The activated carbons, prepared by the one step method, were characterized, and the evolution of their characteristics (yield, adsorption capacities, and porosity) was analyzed as a function of the experimental parameters (activation temperature and activation time), using the Doehlert matrix. The Doehlert matrix allows the response surface to be studied with a good quality parameter estimation of the quadratic model. Each response has been described by a second order model that was adequate to predict responses in all experimental regions. The coefficients of the postulated model were calculated from the experimental responses by means of least squares regression, using the NEMROD software. We determined the region in which the optimum values of both activation temperature and activation time were achieved for the preparation of activated carbons suitable for use in water treatments. The "optimal activated carbon" was experimentally obtained, and its characteristic parameters showed a good agreement with those calculated from the model. The results obtained for activated carbons prepared by the one-step method were compared with those for activated carbons prepared by the two-step method. The characteristics of activated carbons obtained by the one-step and two-step methods showed that "one-step" activated carbons have a highly developed porous texture formed mainly of large macropores and micropores, whereas "two-step" activated carbons have a predominance of mesopores and narrow micropores. These activated carbons from olive-waste cakes showed a high capacity to adsorb herbicides (2,4-dichlorophenoxyacetic acid, 2,4-D; and 2-methyl, 4-chlorophenoxyacetic acid, MCPA) from water, with adsorption capacity values higher than those corresponding to a commercial activated carbon used from drinking water treatments. PMID:12322759

Baçaoui, Abdelaziz; Dahbi, Abderrahman; Yaacoubi, Abdelrani; Bennouna, Chakib; Maldonado-Hódar, Francisco J; Rivera-Utrilla, José; Carrasco-Marín, Francisco; Moreno-Castilla, Carlos

2002-09-01

229

Effect of calcination temperature on physical parameters and photocatalytic activity of mesoporous titania spheres using chitosan/poly(vinyl alcohol) hydrogel beads as a template  

NASA Astrophysics Data System (ADS)

Mesoporous titania spheres were prepared by modified sol-gel method using chitosan/poly(vinyl alcohol) hydrogel beads as a template. Effects of calcination temperature on physical parameters were investigated by X-ray diffraction (XRD), N2 adsorption-desorption, Fourier transform infrared (FT-IR) spectra, thermogravimetry and differential thermal analyses (TG-DTA), high-resolution transmission electron microscope (HRTEM) and scanning electron microscopy (SEM). The photocatalytic activity of mesoporous titania spheres prepared was also evaluated by photocatalytic degradation of phenol as a model molecule under UV irradiation. With increasing calcination temperature, average crystallite size and pore size increased. In contrast, Brunauer-Emmett-Teller (BET) specific surface areas, porosity and pore volumes steadily decreased. Results of characterization proved that prepared titania spheres with highly organized pores were mesoporous structure. The photocatalytic activity of mesoporous titania spheres calcined at 500 °C was more effective than those calcined at other temperatures, which were attributed to the porous structure, large BET surface area, crystalline, and smaller crystallite size. This work may provide new insights into the preparation of novel mesoporous titania spheres and further practical applications in the treatment of wastewater.

Jiang, R.; Zhu, H.-Y.; Chen, H.-H.; Yao, J.; Fu, Y.-Q.; Zhang, Z.-Y.; Xu, Y.-M.

2014-11-01

230

Improvement of the activation of lipase from Candida rugosa following physical and chemical immobilization on modified mesoporous silica.  

PubMed

Lipase from Candida rugosa (CRL) was chemically and physically immobilized onto four types of rod-shaped mesoporous silica (RSMS). RSMS prepared using surfactant P123 and poly(ethylene glycol) as co-templates was functionalized with (3-aminopropyl)triethoxysilane (APTES) to obtain P-RSMS by post-synthesis grafting. Tetraethoxysilane was hydrothermally co-condensed with APTES to obtain C-RSMS. A two-step process using APTES and glutaraldehyde was also performed to obtain G-RSMS. The effects of modification methods (including post-synthesis grafting and co-condensation) and glutaraldehyde on the mesoscopic order, interplanar spacing d100, cell parameter a0, mesoporous structure, and wall thickness of RSMS were studied in detail. Results showed that all samples were mesoporous materials with 2D mesostructures (p6mm). Pore size and d100 decreased, whereas the wall thickness increased after different modifications. CRL was used as a model enzyme to determine the effect of physical and chemical adsorption on loading amount and enzymatic activity. The possible mechanism of CRL immobilization on G-RSMS by chemical adsorption was systematically investigated. The chemical immobilization of CRL on G-RSMS increased the loading amount, hydrolytic activity, thermal stability, and reusability. Moreover, immobilized CRL was employed to catalyze the resolution of 2-octanol by esterification with caprylic acid. The enantiomeric excess of 2-octanol was 45.8% when the reaction was catalyzed by G-RSMS-CRL and decreased to about 38%-39% using the physically immobilized CRL, after 48h of reaction in hexane. PMID:25491828

Wang, Chunfeng; Li, Yanjing; Zhou, Guowei; Jiang, Xiaojie; Xu, Yunqiang; Bu, Zhaosheng

2014-12-01

231

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

232

[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

233

Characteristics of microporous/mesoporous carbons prepared from rice husk under base- and acid-treated conditions.  

PubMed

The study reports the preparation of activated carbon with a high surface area from rice husk using chemical activation with H(3)PO(4) and ZnCl(2). Activated carbon prepared from rice husk usually exhibits low specific surface areas due to its high ash content. However, experimental results show that base-leaching and acid-washing processes can effectively enhance the adsorption capacity of rice-husk carbon. The study also investigates the effects of preparation parameters on the surface characteristics of the carbon. These parameters include the kind of activating agent, before and after treatment procedures, impregnation ratio and activation temperature. The chemical and physical properties of samples were examined by EA, ICP-MS, XRD, FTIR, SEM and a N(2)-adsorption meter. The surface areas obtained from ZnCl(2) and H(3)PO(4) activation are as high as 2434 and 1741 m(2)/g, respectively. These values are higher than that of activated carbon treated with neither base nor acid (1262 and 508 m(2)/g for ZnCl(2) and H(3)PO(4) activation). Thermogravimetric analysis shows that the activation process can be divided into three parts based on temperature zones. The results of this study will be useful in developing resource recovery systems for agricultural biomass. PMID:19595505

Liou, Tzong-Horng; Wu, Shao-Jung

2009-11-15

234

Growth of Hierarchal Mesoporous NiO Nanosheets on Carbon Cloth as Binder-free Anodes for High-performance Flexible Lithium-ion Batteries.  

PubMed

Mesoporous NiO nanosheets were directly grown on three-dimensional (3D) carbon cloth substrate, which can be used as binder-free anode for lithium-ion batteries (LIBs). These mesoporous nanosheets were interconnected with each other and forming a network with interval voids, which give rise to large surface area and efficient buffering of the volume change. The integrated hierarchical electrode maintains all the advantageous features of directly building two-dimensional (2D) nanostructues on 3D conductive substrate, such as short diffusion length, strain relaxation and fast electron transport. As the LIB anode, it presents a high reversible capacity of 892.6?mAh g(-1) after 120 cycles at a current density of 100?mA g(-1) and 758.1?mAh g(-1) at a high charging rate of 700?mA g(-1) after 150 cycles. As demonstrated in this work, the hierarchical NiO nanosheets/carbon cloth also shows high flexibility, which can be directly used as the anode to build flexible LIBs. The introduced facile and low-cost method to prepare NiO nanosheets on flexible and conductive carbon cloth substrate is promising for the fabrication of high performance energy storage devices, especially for next-generation wearable electronic devices. PMID:25491432

Long, Hu; Shi, Tielin; Hu, Hao; Jiang, Shulan; Xi, Shuang; Tang, Zirong

2014-01-01

235

Growth of Hierarchal Mesoporous NiO Nanosheets on Carbon Cloth as Binder-free Anodes for High-performance Flexible Lithium-ion Batteries  

NASA Astrophysics Data System (ADS)

Mesoporous NiO nanosheets were directly grown on three-dimensional (3D) carbon cloth substrate, which can be used as binder-free anode for lithium-ion batteries (LIBs). These mesoporous nanosheets were interconnected with each other and forming a network with interval voids, which give rise to large surface area and efficient buffering of the volume change. The integrated hierarchical electrode maintains all the advantageous features of directly building two-dimensional (2D) nanostructues on 3D conductive substrate, such as short diffusion length, strain relaxation and fast electron transport. As the LIB anode, it presents a high reversible capacity of 892.6 mAh g-1 after 120 cycles at a current density of 100 mA g-1 and 758.1 mAh g-1 at a high charging rate of 700 mA g-1 after 150 cycles. As demonstrated in this work, the hierarchical NiO nanosheets/carbon cloth also shows high flexibility, which can be directly used as the anode to build flexible LIBs. The introduced facile and low-cost method to prepare NiO nanosheets on flexible and conductive carbon cloth substrate is promising for the fabrication of high performance energy storage devices, especially for next-generation wearable electronic devices.

Long, Hu; Shi, Tielin; Hu, Hao; Jiang, Shulan; Xi, Shuang; Tang, Zirong

2014-12-01

236

Growth of Hierarchal Mesoporous NiO Nanosheets on Carbon Cloth as Binder-free Anodes for High-performance Flexible Lithium-ion Batteries  

PubMed Central

Mesoporous NiO nanosheets were directly grown on three-dimensional (3D) carbon cloth substrate, which can be used as binder-free anode for lithium-ion batteries (LIBs). These mesoporous nanosheets were interconnected with each other and forming a network with interval voids, which give rise to large surface area and efficient buffering of the volume change. The integrated hierarchical electrode maintains all the advantageous features of directly building two-dimensional (2D) nanostructues on 3D conductive substrate, such as short diffusion length, strain relaxation and fast electron transport. As the LIB anode, it presents a high reversible capacity of 892.6?mAh g?1 after 120 cycles at a current density of 100?mA g?1 and 758.1?mAh g?1 at a high charging rate of 700?mA g?1 after 150 cycles. As demonstrated in this work, the hierarchical NiO nanosheets/carbon cloth also shows high flexibility, which can be directly used as the anode to build flexible LIBs. The introduced facile and low-cost method to prepare NiO nanosheets on flexible and conductive carbon cloth substrate is promising for the fabrication of high performance energy storage devices, especially for next-generation wearable electronic devices. PMID:25491432

Long, Hu; Shi, Tielin; Hu, Hao; Jiang, Shulan; Xi, Shuang; Tang, Zirong

2014-01-01

237

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

PubMed

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

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

2014-12-19

238

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

239

Enhanced mercuric chloride adsorption onto sulfur-modified activated carbons derived from waste tires.  

PubMed

A number of activated carbons derived from waste tires were further impregnated by gaseous elemental sulfur at temperatures of 400 and 650 degrees C, with a carbon and sulfur mass ratio of 1:3. The capabilities of sulfur diffusing into the micropores of the activated carbons were significantly different between 400 and 650 degrees C, resulting in obvious dissimilarities in the sulfur content of the activated carbons. The sulfur-impregnated activated carbons were examined for the adsorptive capacity of gas-phase mercuric chloride (HgC1) by thermogravimetric analysis (TGA). The analytical precision of TGA was up to 10(-6) g at the inlet HgCl2 concentrations of 100, 300, and 500 microg/m3, for an adsorption time of 3 hr and an adsorption temperature of 150 degrees C, simulating the flue gas emitted from municipal solid waste (MSW) incinerators. Experimental results showed that sulfur modification can slightly reduce the specific surface area of activated carbons. High-surface-area activated carbons after sulfur modification had abundant mesopores and micropores, whereas low-surface-area activated carbons had abundant macropores and mesopores. Sulfur molecules were evenly distributed on the surface of the inner pores after sulfur modification, and the sulfur content of the activated carbons increased from 2-2.5% to 5-11%. After sulfur modification, the adsorptive capacity of HgCl2 for high-surface-area sulfurized activated carbons reached 1.557 mg/g (22 times higher than the virgin activated carbons). The injection of activated carbons was followed by fabric filtration, which is commonly used to remove HgCl2 from MSW incinerators. The residence time of activated carbons collected in the fabric filter is commonly about 1 hr, but the time required to achieve equilibrium is less than 10 min. Consequently, it is worthwhile to compare the adsorption rates of HgCl2 in the time intervals of < 10 and 10-60 min. PMID:22866581

Yuan, Chung-Shin; Wang, Guangzhi; Xue, Sheng-Han; Ie, Iau-Ren; Jen, Yi-Hsiu; Tsai, Hsieh-Hung; Chen, Wei-Jin

2012-07-01

240

Freestanding 3D mesoporous Co?O?@carbon foam nanostructures for ethanol gas sensing.  

PubMed

Metal oxide materials have been widely used as gas-sensing platforms, and their sensing performances are largely dependent on the morphology and surface structure. Here, freestanding flower-like Co3O4 nanostructures supported on three-dimensional (3D) carbon foam (Co3O4@CF) were successfully synthesized by a facile and low-cost hydrothermal route and annealing procedure. The morphology and structure of the nanocomposites were studied by X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive spectroscopy, and scanning electron microscopy (SEM). The SEM characterizations showed that the skeleton of the porous carbon foam was fully covered by flower-like Co3O4 nanostructures. Moreover, each Co3O4 nanoflower is composed of densely packed nanoneedles with a length of ~10 ?m, which can largely enhance the surface area (about 286.117 m(2)/g) for ethanol sensing. Gas sensor based on the as-synthesized 3D Co3O4@CF nanostructures was fabricated to study the sensing performance for ethanol at a temperature range from 180 to 360 °C. Due to the 3D porous structure and the improvement in sensing surface/interface, the Co3O4@CF nanostructure exhibited enhanced sensing performance for ethanol detection with low resistance, fast response and recovery time, high sensitivity, and limit of detection as low as 15 ppm at 320 °C. The present study shows that such novel 3D metal oxide/carbon hybrid nanostructures are promising platforms for gas sensing. PMID:25011608

Li, Lei; Liu, Minmin; He, Shuijian; Chen, Wei

2014-08-01

241

Preparation of activated carbons previously treated with hydrogen peroxide: Study of their porous texture  

NASA Astrophysics Data System (ADS)

Cedar wood was used as raw material for the preparation of activated carbons by treatment with hydrogen peroxide of different concentrations. The samples were next carbonised and activated under CO 2 atmosphere. The activated carbons were characterised by means of the adsorption isotherms of N 2 at 77 K, as well as by applying the Density Functional Theory (DFT) method and mercury porosimetry. The experimental results corresponding to the activated samples indicate a more remarkable porous development as a consequence of the treatment with hydrogen peroxide, probably due to the elimination of surface complexes produced during the activation step. The DFT diagrams point out that the activating treatment favours the development of medium and narrow-size micropores whereas the carbonisation process leads to the development of wide micropores of size close to that corresponding to mesopores.

López de Letona Sánchez, M.; Macías-García, A.; Díaz-Díez, M. A.; Cuerda-Correa, E. M.; Gañán-Gómez, J.; Nadal-Gisbert, A.

2006-06-01

242

A facile one-pot self-assembly approach to incorporate SnOx nanoparticles in ordered mesoporous carbon with soft templating for fuel cells  

NASA Astrophysics Data System (ADS)

Unique SnOx (x = 1,2)/ordered mesoporous carbon nanocomposites (denoted as SnOx/OMC) are firstly synthesized through a ‘one-pot’ synthesis together with the soft template self-assembly approach. The obtained SnOx/OMC nanocomposites with various SnOx contents exhibit uniform pore sizes between 3.9 and 4.2 nm, high specific surface areas between 497 and 595 m2 g-1, and high pore volumes between 0.39 and 0.48 cm3 g-1. With loading of Pt, Pt-SnOx/OMC with relatively low SnOx content exhibits superior electrocatalytic performance, long-term durability, and resistance to CO poisoning for methanol oxidation, as compared to Pt/OMC, PtRu/C and Pt-SnOx/C, which may be attributed not only to the synergetic effect of embedded SnOx, but also to the highly ordered mesostructure with high specific surface areas and large pore volumes affording plenty of surface area for support of Pt nanoparticles. This work supplies an efficient way to synthesize novel ordered mesoporous carbon self-supported metallic oxide as catalyst support and its further potential application to reduce the cost of catalysts in direct methanol fuel cells.

Huang, Yingqiang; Zhai, Zhicheng; Luo, Zhigang; Liu, Yingju; Liang, Zhurong; Fang, Yueping

2014-04-01

243

A facile one-pot self-assembly approach to incorporate SnOx nanoparticles in ordered mesoporous carbon with soft templating for fuel cells.  

PubMed

Unique SnO(x) (x = 1,2)/ordered mesoporous carbon nanocomposites (denoted as SnO(x)/OMC) are firstly synthesized through a 'one-pot' synthesis together with the soft template self-assembly approach. The obtained SnO(x)/OMC nanocomposites with various SnO(x) contents exhibit uniform pore sizes between 3.9 and 4.2 nm, high specific surface areas between 497 and 595 m(2) g(-1), and high pore volumes between 0.39 and 0.48 cm(3) g(-1). With loading of Pt, Pt-SnO(x)/OMC with relatively low SnO(x) content exhibits superior electrocatalytic performance, long-term durability, and resistance to CO poisoning for methanol oxidation, as compared to Pt/OMC, PtRu/C and Pt-SnO(x)/C, which may be attributed not only to the synergetic effect of embedded SnO(x), but also to the highly ordered mesostructure with high specific surface areas and large pore volumes affording plenty of surface area for support of Pt nanoparticles. This work supplies an efficient way to synthesize novel ordered mesoporous carbon self-supported metallic oxide as catalyst support and its further potential application to reduce the cost of catalysts in direct methanol fuel cells. PMID:24598127

Huang, Yingqiang; Zhai, Zhicheng; Luo, Zhigang; Liu, Yingju; Liang, Zhurong; Fang, Yueping

2014-04-01

244

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. PMID:24045767

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

2013-01-01

245

Highly dispersed iron oxide nanoclusters supported on ordered mesoporous SBA15: A very active catalyst for Friedel–Crafts alkylations  

Microsoft Academic Search

Iron oxide supported on ordered mesoporous SBA-15 was prepared by impregnating as-synthesized SBA-15 with a methanolic solution of Fe(NO3)3·9H2O, characterized by X-ray diffraction (XRD), N2 sorption, transmission electron microscopy (TEM), and UV–vis spectroscopy. Characterization revealed that iron oxide was present as highly dispersed nanoclusters in the well-ordered mesoporous channels of SBA-15. The supported material still maintained its ordered mesoporous structure

Yinyong Sun; Stéphane Walspurger; Jean-Philippe Tessonnier; Benoît Louis; Jean Sommer

2006-01-01

246

Mesoporous carbon-coated Li4Ti5O12 spheres for fast Li+ ion insertion/deinsertion in lithium battery anodes  

SciTech Connect

We report on synthesis and electrochemical properties of a family of carbon-coated, mesoporous lithium titanate nanostructures (C@Li{sub 4}Ti{sub 5}O{sub 12}). Synthesized using a scalable solvothermal approach employing low-cost petroleum pitch as the carbon source, the nanostructured C@Li{sub 4}Ti{sub 5}O{sub 12} materials manifest exceptional capacity to reversibly intercalate/de-intercalate lithium at both low and high charge rates. The combination of fast electrolyte and ion transport made possible in the inherently zero-strain material, Li{sub 4}Ti{sub 5}O{sub 12}, is thought to be responsible for our observations.

Navaneedhakrishnan, Jayaprakash; Moganty, Surya S.; Lou, Xiong Wen; Archer, Lynden A.

2011-01-01

247

Synthesis of mesoporous silica hollow nanospheres with multiple gold cores and catalytic activity.  

PubMed

The core-shell Au@resorcinol-formaldehyde (RF) nanospheres with multiple cores have been successfully synthesized by a modified Stöber method. After coating mesoporous silica and the calcination, the Au@meso-SiO2 hollow nanospheres with multiple gold cores can be obtained, which have a high surface area (?537 m(2)/g) and uniform pore size (?2.5 nm). The Au@meso-SiO2 hollow nanospheres can be used as a catalyst for the reduction of 4-nitrophenol by NaBH4 into 4-aminophenol, and exhibit excellent catalytic performance. PMID:24935190

Chen, Junchen; Xue, Zhaoteng; Feng, Shanshan; Tu, Bo; Zhao, Dongyuan

2014-09-01

248

Synthesis and characterization of mesoporous-TiO{sub 2} with enhanced photocatalytic activity for the degradation of chloro-phenol  

SciTech Connect

Mesoporous-titania (TiO{sub 2}) photocatalysts have been synthesized using polyethylene glycol (PEG) as a template in dilute acetic acid aqueous solution by hydrothermal process. The effect of PEG molecular weights and thermal treatment on the resultant structure and photocatalytic activity are investigated. Structural and phase compositional properties of the resultant photocatalysts are characterized by transmission electron microscopy, X-ray diffraction and nitrogen sorption analysis. When the molecular weights of PEG vary from 600 to 20,000, the particle sizes of mesoporous structure decrease from 15.1 to 13.3 nm and mean pore sizes increase from 6.9 to 10.6 nm. The chemical reactions of the formation of mesoporous-TiO{sub 2} during its synthesis have been proposed and discussed. The activities of mesoporous-TiO{sub 2} photocatalysts are evaluated and compared with Degussa P-25 using chloro-phenol as a testing compound. The reaction mechanism of photodegradation is also described on the basis of high performance liquid chromatography.

Shamaila, Sajjad; Sajjad, Ahmed Khan Leghari; Chen, Feng [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China)] [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China); Zhang, Jinlong, E-mail: jlzhang@ecust.edu.cn [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China) [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China); School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550001 (China)

2010-10-15

249

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

250

Synthesis, characterization, and application of surface-functionalized ordered mesoporous nanoparticles  

SciTech Connect

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

Chung, Po-Wen

2009-12-15

251

Photoconductivity of activated carbon fibers  

NASA Astrophysics Data System (ADS)

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 to 2000 sq m/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 20 S/cm at room temperature, increases with increasing temperature in the range 30 to 290 K. 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 bimolecular process at low temperatures. The observed decay time of the photoconductivity is approximately 0.3 sec. 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 approximately 10(exp 21)/cu cm and approximately 20 meV, 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.

Kuriyama, K.; Dresselhaus, M. S.

1990-08-01

252

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

NASA Astrophysics Data System (ADS)

Four kinds of activated carbons (denoted as ACs) with specific surface area of ca. 1050 m 2 g -1 were fabricated from fir wood and pistachio shell by means of steam activation or chemical activation with KOH. Pore structures of ACs were characterized by a t-plot method based on N 2 adsorption isotherms. The amount of mesopores within KOH-activated carbons ranged from 9.2 to 15.3% while 33.3-49.5% of mesopores were obtained for the steam-activated carbons. The pore structure, surface functional groups, and raw materials of ACs, as well as pH and the supporting electrolyte were also found to be significant factors determining the capacitive characteristics of ACs. The excellent capacitive characteristics in both acidic and neutral media and the weak dependence of the specific capacitance on the scan rate of cyclic voltammetry (CV) for the ACs derived from the pistachio shell with steam activation (denoted as P-H 2O-AC) revealed their promising potential in the application of supercapacitors. The ACs derived from fir wood with KOH activation (denoted as F-KOH-AC), on the other hand, showed the best capacitive performance in H 2SO 4 due to excellent reversibility and high specific capacitance (180 F g -1 measured at 10 mV s -1), which is obviously larger than 100 F g -1 (a typical value of activated carbons with specific surface areas equal to/above 1000 m 2 g -1).

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

253

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

254

Novel mesoporous NiO/HTiNbO5 nanohybrids with high visible-light photocatalytic activity and good biocompatibility  

NASA Astrophysics Data System (ADS)

Mesoporous nanohybrids of NiO nanoparticles and HTiNbO5 nanosheets have been successfully synthesized by first exfoliating layered HTiNbO5 in tetrabutylammonium hydroxide (TBAOH) to obtain HTiNbO5 nanosheets, then reassembling with a nickel precursor and finally heating with urea. The resulting samples were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, photoluminescence spectroscopy (PL) and N2 adsorption-desorption measurements. It was found that the as-prepared nanohybrids had a relatively large interlayer spacing of 1.05 nm. After calcination, the titanoniobate nanosheet was still retained and the pore size of the resulting nanohybrids became larger. Compared with the original HTiNbO5, the obtained nanohybrids were mesoporous with a greatly expanded surface area (~75-115 m2 g-1), a much strengthened absorption in the UV light region and a visible-light response. Nickel atoms were present in the form of Ni-O in the nanohybrid, and NiO nanoparticles were homogeneously distributed with an average particle size of 2-3 nm, giving rise to the visible light response. The catalytic activities of the obtained samples were evaluated by the photodegradation of RhB solution under visible light irradiation. The introduction of urea during the calcination process not only increased the thermal stability and surface area, but also decreased the rate of recombination of photogenerated holes and electrons, leading to a greatly enhanced photocatalytic activity of the resulting nanohybrids. The dye molecules were mainly degraded to aliphatic organic compounds and partially mineralized to CO2 and/or CO, rather than being simply decolorized. In addition, cell viability results for HepG2 cells show that the as-prepared sample have good biocompatibility.

Zhai, Zheng; Yang, Xiaoyan; Xu, Lin; Hu, Chenhui; Zhang, Lihong; Hou, Wenhua; Fan, Yining

2012-01-01

255

Mesoporous TiO2 Spheres Interconnected by Multiwalled Carbon Nanotubes as an Anode for High-Performance Lithium Ion Batteries.  

PubMed

We report on the excellent electrochemical response of lithium ion batteries that use a composite material comprised of mesoporous titanium dioxide (MTO) spheres and multiwalled carbon nanotubes (MWCNTs) for the anode. The composite structure was synthesized via a combined sol-gel and solvothermal method, and the batteries exhibited unprecedented discharge capacity, cycling stability, and reversibility when compared to those based on commercially available TiO2 nanopowders and mesoporous TiO2 spheres. The inclusion of the composite structure resulted in an improvement in electronic and ionic conductivity, a larger surface area, and a colossal number of open channels in the synthesized structure that allowed for lithium ion intercalation. We achieved a Coulombic efficiency of nearly 100% and a discharge capacity as high as 316 mA h g(-1) at a rate of C/5, which is 1.9 times higher than that which is practically attainable with TiO2. Moreover, we observed a capacity loss of only 3.1% after 100 cycles, which indicates that the synthesized structure has a highly stable nature. PMID:25633801

Trang, Nguyen Thi Hong; Ali, Zahid; Kang, Dae Joon

2015-02-18

256

Hydrothermal synthesis, characterization, photocatalytic activity and dye-sensitized solar cell performance of mesoporous anatase TiO{sub 2} nanopowders  

SciTech Connect

Mesoporous anatase TiO{sub 2} nanopowder was synthesized by hydrothermal method at 130 deg. C for 12 h. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), HRTEM, and Brunauer-Emmett-Teller (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{sup 2}/g. Mesoporous anatase TiO{sub 2} nanopowders (prepared by this study) showed higher photocatalytic activity than the nanorods TiO{sub 2}, nanofibers TiO{sub 2} mesoporous TiO{sub 2}, and commercial TiO{sub 2} nanoparticles (P-25, JRC-01, and JRC-03). The solar energy conversion efficiency ({eta}) of the cell using the mesoporous anatase TiO{sub 2} was about 6.30% with the short-circuit current density (Jsc) of 13.28 mA/cm{sup 2}, the open-circuit voltage (Voc) of 0.702 V and the fill factor (ff) of 0.676; while {eta} of the cell using P-25 reached 5.82% with Jsc of 12.74 mA/cm{sup 2}, Voc of 0.704 V and ff of 0.649.

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); Jitputti, Jaturong; Ngamsinlapasathian, Supachai [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

2008-01-08

257

Formation of continuous activated carbon fibers for barrier fabrics  

NASA Astrophysics Data System (ADS)

Commercial protective suits made of active carbon granules or nonwoven fabrics are heavy, have low moisture vapor transport rate, and are uncomfortable. Inherent problems due to construction of barrier fabrics lead to severe heat stress when worn for even short time in warm environments. One proposed method to eliminate these problems is to facilitate the construction of a fabric made of continuous activated carbon fibers (CACF). This study is directed toward investigating the possibility of developing CAFC from two precursors: aramid and fibrillated PAN fiber. It was shown in this study that Kevlar-29 fibers could be quickly carbonized and activated to CACF with high adsorptivity and relatively low weight loss. CACF with high surface area (>500 msp2/g) and reasonable tenacity (?1g/denier) were successfully prepared from Kevlar fibers through a three-step process: pretreatment, carbonization, and activation. X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and thermal analysis were conducted to understand the evolution of physical and chemical properties during pretreatment. The influence of temperature, heating rate, and pyrolysis environment on the thermal behavior was determined by DSC and TGA/DTA and used as an indicator for optimizing the pyrolysis conditions. Surface analysis by nitrogen isotherms indicated that the resultant fibers had micropores and mesopores on the surface of CACF. This was also inferred by studies on the surface morphology through Scanning Electron Microscopy (SEM) and Scanning Tunneling Microscopy (STM). An investigation of the surface chemical structure by X-ray photoelectron spectroscopy (XPS) before and after activation and elemental analysis confirmed that adsorption of Kevlar based CACF mainly arises due to the physisorption instead of chemisorption. A multistep stabilization along with carbonization and activation was used to prepare active carbon fiber from fibrillated PAN fiber. The resultant fiber retained its fibrillar structure and provided a very high surface area, up to 1400 msp2/g, but was brittle. The characterization of the thermal behavior, mechanical properties, and surface structure of the pyrolyzed fiber at each processing step was also carried out by using various techniques, such as DSC and TGA, Instron, and SEM. These studies provide directions for preparation of CACF from novel precursors.

Liang, Ying

1997-08-01

258

Activated carbon adsorption of humic substances  

SciTech Connect

Activated carbon pore-size distribution is an important parameter relative to the carbon's capacity for adsorbing humic substances. The effect of coagulation on adsorption should also be examined wherever granular activated carbon is to be used following coagulation. Experimental investigations using a commercial humic acid and a fulvic acid extracted from peat, and a number of commercial activated carbons, several of which were coal-based, are reported.

Lee, M.C.

1981-08-01

259

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

PubMed

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

Qian, Qingrong; Machida, Motoi; Tatsumoto, Hideki

2008-01-01

260

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

PubMed

Here we describe the development of novel nanostructured coating systems with improved photocatalytic and antibacterial activities. These systems comprise a layer of SiO2 followed by a layer of mesoporous or dense TiO2-anatase, and doping with silver nanoparticles (Ag NPs). The coatings were synthesized via a sol-gel technique by combining colloidal Ag NPs with TiO2 and SiO2 sols. The photocatalytic activity was studied through methyl orange decomposition under UV light. Results showed a great increase of photocatalytic activity by Ag NPs doping. The most active photocatalyst corresponded to the Ag-SiO2/TiO2 mesoporous system, associated with the porosity of the coatings and with the decrease of e-h recombination for the presence of Ag NPs. All the TiO2 coatings showed a strong bactericidal activity against planktonic forms of Gram-negative (enterohemorrhagic Escherichia coli) and Gram-positive (Listeria monocytogenes) pathogens, as well as a strong germicidal effect against deadly spores of human gas gangrene- and anthrax-producing bacteria (Clostridium perfringens and Bacillus anthracis, respectively). The bactericidal and sporocidal activity was improved by doping the coatings with Ag NPs, even more when nanoparticles were in the outer layer of TiO2, because they are more accessible to the environment. The mechanisms responsible for the increase of photocatalytic and bactericidal behaviors related to Ag NP doping were studied by spectroscopic ellipsometry, UV-vis spectroscopy, photoluminescence and anodic stripping voltammetry. It was found that the separation of the electron-hole pair contributed to the enhancement of photocatalysis, whereas the effect of the local electric field reinforcement was probably present. A possible involvement of a decrease of band-gap energy and dispersion by silver nanoparticles is ruled out. bactericidal efficacy was increased by Ag(+) ion release. Overall, the results included in this article show that the architecture of the films may tune photocatalytic and bactericidal properties. PMID:25175258

Roldán, María V; de Oña, Paula; Castro, Yolanda; Durán, Alicia; Faccendini, Pablo; Lagier, Claudia; Grau, Roberto; Pellegri, Nora S

2014-10-01

261

Brazilian natural fiber (jute) as raw material for activated carbon production.  

PubMed

Jute fiber is the second most common natural cellulose fiber worldwide, especially in recent years, due to its excellent physical, chemical and structural properties. The objective of this paper was to investigate: the thermal degradation of in natura jute fiber, and the production and characterization of the generated activated carbon. The production consisted of carbonization of the jute fiber and activation with steam. During the activation step the amorphous carbon produced in the initial carbonization step reacted with oxidizing gas, forming new pores and opening closed pores, which enhanced the adsorptive capacity of the activated carbon. N2 gas adsorption at 77K was used in order to evaluate the effect of the carbonization and activation steps. The results of the adsorption indicate the possibility of producing a porous material with a combination of microporous and mesoporous structure, depending on the parameters used in the processes, with resulting specific surface area around 470 m2.g-1. The thermal analysis indicates that above 600°C there is no significant mass loss. PMID:25590747

Rombaldo, Carla F S; Lisboa, Antonio C L; Mendez, Manoel O A; Coutinho, Aparecido R

2014-12-01

262

Reducing the chlorine dioxide demand in final disinfection of drinking water treatment plants using activated carbon.  

PubMed

Abstract Chlorine dioxide is one of the most widely employed chemicals in the disinfection process of a Drinking Water Treatment Plant (DWTP). The aim of this work was to evaluate the influence of the adsorption process with granular activated carbon (GAC) on the chlorine dioxide consumption in final oxidation/disinfection. A first series of tests were performed at laboratory scale employing water samples collected at the outlet of the DWTP sand filter of Cremona (Italy). The adsorption process in batch conditions with seven different types of GAC was studied. A second series of tests were performed on water samples collected at the outlet of four GAC columns installed at the outlet of the DWTP sand filter. The results showed that the best chlorine dioxide demand (ClO2-D) reduction yields are equal to 60-80% and are achieved in the first 30 minutes after the ClO2 addition, during the first 16 days of the column operation using a mineral, coal-based, meso-porous GAC. Therefore, this carbon removes the organic compounds that are more rapidly reactive with ClO2. Moreover, a good correlation was found between the ClO2-D and the UV absorbance at wavelength 254 using mineral carbons; therefore, the use of a mineral meso-porous GAC is an effective solution to control the high ClO2-D in the disinfection stage of a DWTP. PMID:25465650

Sorlini, Sabrina; Biasibetti, Michela; Collivignarelli, Maria Cristina; Crotti, Barbara Marianna

2014-12-01

263

Preparation of a carbon-based solid acid catalyst by sulfonating activated carbon in a chemical reduction process.  

PubMed

Sulfonated (SO(3)H-bearing) activated carbon (AC-SO(3)H) was synthesized by an aryl diazonium salt reduction process. The obtained material had a SO(3)H density of 0.64 mmol·g-1 and a specific surface area of 602 m2·g-1. The catalytic properties of AC-SO(3)H were compared with that of two commercial solid acid catalysts, Nafion NR50 and Amberlyst-15. In a 10-h esterification reaction of acetic acid with ethanol, the acid conversion with AC-SO(3)H (78%) was lower than that of Amberlyst-15 (86%), which could be attributed to the fact that the SO(3)H density of the sulfonated carbon was lower than that of Amberlyst-15 (4.60 mmol·g-1). However, AC-SO(3)H exhibited comparable and even much higher catalytic activities than the commercial catalysts in the esterification of aliphatic acids with longer carbon chains such as hexanoic acid and decanoic acid, which may be due to the large specific surface area and mesoporous structures of the activated carbon. The disadvantage of AC-SO(3)H is the leaching of SO(3)H group during the reactions. PMID:20956883

Liu, Xiao-Yan; Huang, Miao; Ma, Hai-Long; Zhang, Zeng-Qiang; Gao, Jin-Ming; Zhu, Yu-Lei; Han, Xiao-Jin; Guo, Xiang-Yun

2010-01-01

264

Synthesis of mesoporous SAPO-34 zeolite from mesoporous silica materials for methanol to light olefins.  

PubMed

Mesoporous SAPO-34 zeolites were synthesized by using as-prepared mesoporous silica material as both silica source and mesopore tailor. The mesoporous SAPO-34 zeolite materials thus obtained are characterized by a series of different techniques, including poweder X-ray diffraction pattern, nitrogen physisorption analysis, scanning electron micrograph, temperature programmed desorption of ammonia, and inductively coupled plasma atomic emission spectrometry. The resultant mesoporous SAPO-34 crystals exhibit sphere-like particle with zeolite layer units. The mesopore size distribution and particle size can be changed by amounts of silica source and water. The methanol-to-olefins (MTO) reactions using these mesoporous SAPO-34 zeolites are carried out with a fixed-bed reactor. Catalytic tests exhibit that the mesoporous SAPO-34 zeolite materials show high catalytic activity compared with the conventional SAPO-34 for MTO reaction. The better catalytic activity and longer life time of the mesoporous SAPO-34 catalysts in MTO are mainly due to the existence of the mesoporosity of SAPO-34 with small particle size. PMID:24245281

Kang, Eun A; Kim, Tae-Wan; Chae, Ho-Jeong; Kim, Min; Jeong, Kwang-Eun; Kim, Joo-Wan; Kim, Chul-Ung; Jeong, Soon-Yong

2013-11-01

265

Porous carbon nitride nanosheets for enhanced photocatalytic activities.  

PubMed

Porous carbon nitride nanosheets (PCNs) have been prepared for the first time by a simple liquid exfoliation method via probe sonication. These mesoporous nanosheets of around 5 nm in thickness combine several advantages including high surface area, enhanced light absorption and excellent water dispersity. It can be used as a versatile support for co-catalyst loading for photocatalytic dye degradation and water reduction. With 3.8 wt% Co3O4 loaded, PCNs can achieve more efficient photocatalytic degradation of Rhodamine B, compared with non-porous C3N4 nanosheets (CNs), bulk porous C3N4 (PCN) and bulk nonporous C3N4 (CN). With 1.0 wt% Pt loaded, CNs and PCN exhibit 7-8 times enhancement in H2 evolution than CN. Remarkably, PCNs with both porous and nanosheet-like features achieve 26 times higher activity in H2 evolution than CN. These significant improvements in photocatalytic activities can be attributed to the high surface area as well as better electron mobility of the two-dimensional nanostructure. PMID:25362966

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

2014-12-21

266

Adsorption of herbicides using activated carbons  

SciTech Connect

This work describes development of a series of novel activated carbon materials and their testing for possible water treatment applications by studying the adsorption of sodium pentachlorphenolate, PCP (a common herbicide/wood preservative). Although the application of activated carbons is an established technology for the treatment of public water supplies, there is a growing need for materials with higher selectivity and adsorptive capacities as well as high abrasion resistance. The materials that will be discussed include extruded wood-derived carbons with novel pore size distributions and high hardness, as well as activated carbon fiber composites. Comparisons will be made with commercial granular water treatment carbons.

Derbyshire, F.; Jagtoyan, M.; Lafferty, C.; Kimber, G. [Univ. of Kentucky, Lexington, KY (United States)

1996-10-01

267

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

2012-07-18

268

Synthesis, characterization and catalytic activity of Mn(III)- and Co(II)-salen complexes immobilized mesoporous alumina  

Microsoft Academic Search

Mn(III) and Co(II)–schiff base complexes were immobilized over mesoporous alumina through the reaction of mesoporous alumina functionalized 3-aminopropyl triethoxy silane (3-APTES) and salicylic aldehyde via schiff base condensation. The surface properties of the functionalized catalysts were analyzed by a series of characterization techniques like elemental analysis, PXRD, FTIR, N2 adsorption–desorption, TG-DTG, DR UV–vis, XPS, etc. PXRD and adsorption–desorption analysis shows

V. D. Chaube; S. Shylesh; A. P. Singh

2005-01-01

269

Fabrication of meso-porous BiOI sensitized zirconia nanoparticles with enhanced photocatalytic activity under simulated solar light irradiation  

NASA Astrophysics Data System (ADS)

In this present work, BiOI sensitized zirconia (BiOI-ZrO2) nanoparticles were fabricated using a precipitation-deposition method. The physicochemical characteristics of BiOI/ZrO2 were studied through X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), BET-surface area, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis-DRS) and photoluminescence (PL) spectroscopy techniques. The absorption maximum of ZrO2 was shifted to the visible region after sensitization with BiOI. BET-surface area results inferred that the prepared hetero-junctions were meso-porous in nature. The photocatalytic activity of BiOI-ZrO2 for the degradation of methyl violet (MV) dye under simulated solar light irradiation was investigated in detail. 3% BiOI-ZrO2 exhibited the highest photocatalytic performance (98% of MV degradation) when compared with ZrO2 and BiOI. The enhancement in the photocatalytic activity of BiOI-ZrO2 is ascribed to the sensitization effect of BiOI, suppression of electron-hole recombination and the formation of p-n hetero-junction.

Vignesh, K.; Suganthi, A.; Min, Bong-Ki; Kang, Misook

2015-01-01

270

Properties of differently shaped activated carbon fibers  

Microsoft Academic Search

Differently shaped carbon fibers (R-, I-, C-, Y-, and X-type) were prepared from melt-spinning of reformed naphtha cracking\\u000a bottom oil precursors through various shaped spinnerets. These carbon fibers were activated by steam and activation properties\\u000a were compared. The decrease of hydraulic radius resulted in the extending of the external surface area of carbon fibers. Activation\\u000a energy and rate of differently

Sang-Yong Eom; Seung-Kon Ryu

2010-01-01

271

Hard templating synthesis of mesoporous and nanowire SnO2 lithium battery anode materials  

E-print Network

Hard templating synthesis of mesoporous and nanowire SnO2 lithium battery anode materials Hyesun as an Advance Article on the web 8th January 2008 DOI: 10.1039/b714904b Mesoporous and nanowire SnO2 anode materials. Recently, Ryoo's group reported the preparation of ordered mesoporous carbon using highly ordered

Cho, Jaephil

272

A tyrosinase biosensor based on ordered mesoporous carbon-Au/L-lysine/Au nanoparticles for simultaneous determination of hydroquinone and catechol.  

PubMed

A novel biosensor was developed based on tyrosinase immobilization with ordered mesoporous carbon-Au (OMC-Au), L-lysine membrane and Au nanoparticles on a glassy carbon electrode (GCE). It was applied for the simultaneous determination of dihydroxybenzene isomers using differential pulse voltammetry (DPV). The tyrosinase/OMC-Au/L-lysine/Au film was characterized by scanning electron microscopy (SEM) and impedance spectra. Under optimized conditions, the DPV study results for two isomers, hydroquinone (HQ, 1,4-dihydroxybenzene) and catechol (CC, 1,2-dihydroxybenzene) showed low peak potentials, and the peak-to-peak difference was about 135.85 mV, which ensured the anti-interference ability of the biosensor and made simultaneous detection of dihydroxybenzene isomers possible in real samples. DPV peak currents increased linearly with concentration over the range of 4.0 × 10(-7) to 8.0 × 10(-5) M, and the detection limits of hydroquinone and catechol were 5 × 10(-8) M and 2.5 × 10(-8) M (S/N = 3), respectively. The tyrosinase biosensor exhibited good repeatability and stability. In addition, the response mechanism of enzyme catalysed redox on the OMC-Au/L-lysine/Au film modified electrode based on electrochemical study was discussed. The proposed method could be extended for the development of other enzyme-based biosensors. PMID:23671910

Tang, Lin; Zhou, Yaoyu; Zeng, Guangming; Li, Zhen; Liu, Yuanyuan; Zhang, Yi; Chen, Guiqiu; Yang, Guide; Lei, Xiaoxia; Wu, Mengshi

2013-06-21

273

Activated carbon mitigates mercury and methylmercury bioavailability in contaminated sediments.  

PubMed

There are few available in situ remediation options for Hg contaminated sediments, short of capping. Here we present the first tests of activated carbon and other sorbents as potential in situ amendments for remediation of mercury and methylmercury (MeHg), using a study design that combined 2 L sediment/water microcosms with 14 day bioaccumulation assays. Our key end points were pore water concentrations, and bioaccumulation of total Hg and MeHg by a deposit-feeding oligochaete Lumbriculus variegatus. Four amendments were tested: an activated carbon (AC); CETCO Organoclay MRM (MRM); Thiol-SAMMS (TS), a thiol-functionalized mesoporous silica; and AMBERSEP GT74, an ion-exchange resin. Amendments were tested in four separate microcosm assays using Hg-contaminated sediments from two freshwater and two estuarine sites. AC and TS amendments, added at 2-7% of the dry weight of sediments significantly reduced both MeHg concentrations in pore waters, relative to unamended controls (by 45-95%) and bioaccumulation of MeHg by Lumbriculus (by between 30 and 90%). Both amendments had only small impacts on microcosm surface water, sediment and pore water chemistry, with the exception of significant reductions in pore water dissolved organic matter. The effectiveness of amendments in reducing bioaccumulation was well-correlated with their effectiveness in increasing sediment:water partitioning, especially of MeHg. Sediments with low native sediment:water MeHg partition coefficients were most effectively treated. Thus, in situ sediment sorbent amendments may be able to reduce the risk of biotic Hg and MeHg uptake in contaminated sediments, and subsequent contamination of food webs. PMID:24156748

Gilmour, Cynthia C; Riedel, Georgia S; Riedel, Gerhardt; Kwon, Seokjoon; Landis, Richard; Brown, Steven S; Menzie, Charles A; Ghosh, Upal

2013-11-19

274

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

NASA Astrophysics Data System (ADS)

A new carboxylic acid functionalized mesoporous organic polymer has been synthesized via in situ radical polymerization of divinylbenzene and acrylic acid using a mesoporous silica as a seed during the polymerization process under solvothermal conditions. The mesoporous material MPDVAA-1 has been thoroughly characterized employing powder XRD, solid state 13C cross polarization magic angle spinning-nuclear magnetic resonance, FT-IR spectroscopy, N2 sorption, HR-TEM, and NH3 temperature programmed desorption-thermal conductivity detector (TPD-TCD) analysis to understand its porosity, chemical environment, bonding, and surface properties. The mesoporous polymer was used as a catalyst for a three comp onent Biginelli condensation between various aldehydes, ?-keto esters, and urea/thioureas to give 3,4-dihydropyrimidine-2(1H)-ones. The reactions were carried out under conventional heating as well as solvent-free microwave irradiation of solid components, and in both the cases, the mesoporous polymer MPDVAA-1 proved to be a powerful, robust, and reusable catalyst with high catalytic efficiency.

Gomes, Ruth; Dutta, Saikat; Bhaumik, Asim

2014-11-01

275

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

SciTech Connect

A new carboxylic acid functionalized mesoporous organic polymer has been synthesized via in situ radical polymerization of divinylbenzene and acrylic acid using a mesoporous silica as a seed during the polymerization process under solvothermal conditions. The mesoporous material MPDVAA-1 has been thoroughly characterized employing powder XRD, solid state {sup 13}C cross polarization magic angle spinning-nuclear magnetic resonance, FT-IR spectroscopy, N{sub 2} sorption, HR-TEM, and NH{sub 3} temperature programmed desorption-thermal conductivity detector (TPD-TCD) analysis to understand its porosity, chemical environment, bonding, and surface properties. The mesoporous polymer was used as a catalyst for a three comp onent Biginelli condensation between various aldehydes, ?-keto esters, and urea/thioureas to give 3,4-dihydropyrimidine-2(1H)-ones. The reactions were carried out under conventional heating as well as solvent-free microwave irradiation of solid components, and in both the cases, the mesoporous polymer MPDVAA-1 proved to be a powerful, robust, and reusable catalyst with high catalytic efficiency.

Gomes, Ruth; Bhaumik, Asim [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Dutta, Saikat [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2014-11-01

276

Controlling Porosity to Improve Activated Carbon Applications  

NASA Astrophysics Data System (ADS)

This chapter presents an overview of preparation and characterization of activated carbons (ACs), activated carbon fibres (ACFs) and activated carbon monoliths (ACMs) to be used in different applications. Examples of the performance of these materials in environmental, energy storage and space applications are presented, remarking the importance of carrying out a suitable porous texture characterization of the materials to understand and optimize their performance in each application. Development of narrow microporosity, which is assessed by CO2 adsorption at 273 K, has been demonstrated to be necessary for these applications. This type of porosity has been obtained by chemical alkaline hydroxide activation of carbon precursors with careful control and thorough understanding of the variables affecting the carbon activation process.

Linares-Solano, Angel; Lozano-Castelló, D.; Lillo-Ródenas, M. A.; Cazorla-Amorós, D.

277

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

278

One-pot synthesis of nitrogen and sulfur co-doped onion-like mesoporous carbon vesicle as an efficient metal-free catalyst for oxygen reduction reaction in alkaline solution  

NASA Astrophysics Data System (ADS)

Nitrogen and sulfur co-doped onion-like mesoporous carbon vesicle (NS-MCV) with multilayer lamellar structure is synthesized as a metal-free catalyst through a convenient and economical procedure. The synthesized materials are systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectra, nitrogen adsorption-desorption, and X-ray photoelectron spectroscopy (XPS). The characterization results demonstrate that N and S atoms can be successfully doped into the framework of MCV with little impact on the morphology and structure. The NS-MCV manifests a remarkably high electrocatalytic activity as a metal-free electrocatalyst for the oxygen reduction reaction (ORR) with mainly a four-electron transfer pathway. Moreover, in contrast to the commercially available Pt/C catalyst, the NS-MCV shows much better long-term stability and tolerance toward methanol crossover in an alkaline medium. Such excellent performances can be mainly attributed to the synergistic effect arising from the addition of N and S heteroatom, optimized S content and high surface area. The NS-MCV with a simple synthesis method may further exploited as potentially efficient and inexpensive metal-free ORR catalyst materials.

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

2014-12-01

279

A facile soft-template synthesis of mesoporous polymeric and carbonaceous nanospheres  

NASA Astrophysics Data System (ADS)

Owing to the weak self-assembly ability of precursor components and the serious crosslinking of neighbouring nanospheres during a hydrothermal process, the synthesis of monodisperse mesoporous polymer nanospheres with diameters below 500?nm remains a great challenge. Here we extend the synthesis method of mesoporous silica nanospheres to enable the preparation of ordered mesoporous resorcinol formaldehyde nanospheres with particle size from 80 to 400?nm and mesopores of ~3.5?nm in diameter. By finely tuning the synthesis parameters, multi-layered mesoporous resorcinol formaldehyde hollow nanospheres can be successfully synthesized. Mesoporous carbon nanospheres and hollow nanospheres with high surface area are further obtained through carbonization of the polymer spheres. The resulting mesoporous carbon nanospheres are demonstrated as the host cathode material for lithium-sulphur batteries. The synthesis strategy provides a benchmark for fabricating well-defined porous carbonaceous nanospheres with potential for energy storage and conversion applications.

Liu, Jian; Yang, Tianyu; Wang, Da-Wei; Lu, Gao Qing (Max); Zhao, Dongyuan; Qiao, Shi Zhang

2013-12-01

280

Catalytic Growth of Macroscopic Carbon Nanofibers Bodies with Activated Carbon  

NASA Astrophysics Data System (ADS)

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° C for an hour in each step. The catalytic growth of nanocarbon in C2H4/H2 was carried out at temperature of 550° C for 2 hrs with different rotating angle in the fluidization system. SEM and N2 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.; Rinaldi, A.; Muhammad, I. S.; Hamid, S. B. Abd.; Su, D. S.; Schlogl, R.

2009-06-01

281

The effect of carbonization temperature of PAN fiber on the properties of activated carbon fiber composites  

Microsoft Academic Search

The PAN (polyacrylonitrile) based carbon fiber composites were prepared from mixtures of chopped carbon fibers and phenolic resin. Two different carbon fibers were obtained by carbonization of stabilized PAN fiber precursors in nitrogen at 1073 and 1273 K, respectively. Samples of activated carbon fiber composites (ACFCs) were prepared from the carbon fiber composites by activation in carbon dioxide at 1123

J. C. Lee; B. H. Lee; B. G. Kim; M. J. Park; D. Y. Lee; I. H. Kuk; H. Chung; H. S. Kang; H. S. Lee; D. H. Ahn

1997-01-01

282

Self-assembled mesoporous TiO2/carbon nanotube composite with a three-dimensional conducting nanonetwork as a high-rate anode material for lithium-ion battery  

NASA Astrophysics Data System (ADS)

Mesoporous three-dimensional (3D) TiO2/carbon nanotube conductive hybrid nanostructures can be successfully developed using polyethylene oxide (PEO) to modify the surfaces of carbon nanotubes (CNTs). During the synthesis process, PEO acts as not only “bridges” to connect the TiO2 nanoparticles to the CNT surfaces but also as “hosts” to accommodate and stabilize the in situ generated TiO2 particles. As the electrodes for lithium-ion batteries, such mesoporous 3D TiO2/CNT hybrids, demonstrate high Li storage capacity, superior rate performance and excellent long-term cycling stability. They exhibit a reversible specific capacity of 203 mA h g-1 at 100 mA g-1 and a stable capacity retention of 91 mA h g-1 at 8000 mA g-1 (47.6 C) over 100 cycles; they also retain approximately 90% (71 mA h g-1) of their initial discharge capacity after 900 cycles at an extremely high rate of 15,000 mA g-1 (89 C). This facile synthetic strategy to construct mesoporous 3D TiO2/CNT conductive hybrids provides a convenient route that efficiently assembles various inorganic oxide components on the CNTs' surfaces and enables the formation of heterogeneous nanostructures with novel functionalities. In particular, utilizing a conductive 3D CNT network can serve as a promising strategy for developing high-performance electrodes for Li secondary batteries and supercapacitors.

Wang, Jie; Ran, Ran; Tade, Moses O.; Shao, Zongping

2014-05-01

283

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

284

Intrinsic relationship between enhanced oxygen reduction reaction activity and nanoscale work function of doped carbons.  

PubMed

Nanostructured carbon materials doped with a variety of heteroatoms have shown promising electrocatalytic activity in the oxygen reduction reaction (ORR). However, understanding of the working principles that underpin the superior ORR activity observed with doped nanocarbons is still limited to predictions based on theoretical calculations. Herein, we demonstrate, for the first time, that the enhanced ORR activity in doped nanocarbons can be correlated with the variation in their nanoscale work function. A series of doped ordered mesoporous carbons (OMCs) were prepared using N, S, and O as dopants; the triple-doped, N,S,O-OMC displayed superior ORR activity and four-electron selectivity compared to the dual-doped (N,O-OMC and S,O-OMC) and the monodoped (O-OMC) OMCs. Significantly, the work functions of these heteroatom-doped OMCs, measured by Kelvin probe force microscopy, display a strong correlation with the activity and reaction kinetics for the ORR. This unprecedented experimental insight can be used to provide an explanation for the enhanced ORR activity of heteroatom-doped carbon materials. PMID:24911055

Cheon, Jae Yeong; Kim, Jong Hun; Kim, Jae Hyung; Goddeti, Kalyan C; Park, Jeong Young; Joo, Sang Hoon

2014-06-25

285

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

PubMed

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 5 A, 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 adsorption than the microporous materials. Furthermore, zeolite 13X, which has wider pores than zeolite 5 A, exhibits a higher adsorption capacity. PMID:15499926

Díaz, Eva; Ordóñez, Salvador; Vega, Aurelio; Coca, José

2004-09-17

286

Chemical activation of carbon mesophase pitches.  

PubMed

This paper studies the chemical activation of mesophase pitches of different origins in order to obtain activated carbons suitable for use as electrodes in supercapacitors. The effect that the activating agent (NaOH, LiOH, and KOH), the alkaline hydroxide/pitch ratio, and the activation temperature had on the characteristics of the resultant activated carbons was studied. LiOH was found to be a noneffective activating agent, while activation with NaOH and KOH yielded activated carbons with high apparent surface areas and pore volumes. The increase of the KOH/pitch ratio caused an increase of the chemical attack on the carbon, producing higher burnoffs and development of porosity. Extremely high apparent surface areas were obtained when the petroleum pitch was activated with 5:1 KOH/carbon ratio. The increase of the activation temperature caused an increase of the burnoff, although the differences were not as significant as those derived from the use of different proportions of activating agent. PMID:16376916

Mora, E; Blanco, C; Pajares, J A; Santamaría, R; Menéndez, R

2006-06-01

287

Sensitive impedimetric biosensor based on duplex-like DNA scaffolds and ordered mesoporous carbon nitride for silver(I) ion detection.  

PubMed

This study demonstrates a new, unlabeled immobilized DNA-based biosensor with ordered mesoporous carbon nitride material (MCN) for the detection of Ag(+) by electrochemical impedance spectroscopy (EIS) with [Fe(CN)6](4-/3-) as the redox couple. The unlabeled immobilized DNA initially formed the hairpin-like structure through hybridization with the probe, and then changed to duplex-like structure upon interaction with Ag(+) in solution to form a C-Ag(+)-C complex at electrode surface. As a result, the interfacial charge-transfer resistance of the electrode towards the [Fe(CN)6](4-/3-) redox couple was changed. Thus, a declined charge transfer resistance (Rct) was obtained, corresponding to Ag(+) concentration. MCN provide an excellent platform for DNA immobilization and faster electron transfer. Impedance data were analyzed with the help of Randles equivalent circuit. The lower detection limit of the biosensor for Ag(+) is 5 × 10(-11) M with good specificity. All results showed that this novel approach provides a reliable method for Ag(+) detection with sensitivity and specificity, potentially useful for practical applications. Moreover, other DNA detection methods for more heavy metals may be obtained from this idea and applied in the environmental field. PMID:25346956

Zhou, Yaoyu; Tang, Lin; Xie, Xia; Zeng, Guangming; Wang, Jiajia; Deng, Yaocheng; Yang, Guide; Zhang, Chen; Zhang, Yi; Chen, Jun

2014-12-21

288

Amperometric L-lactate biosensor based on screen-printed carbon electrode containing cobalt phthalocyanine, coated with lactate oxidase-mesoporous silica conjugate layer.  

PubMed

A novel amperometric biosensor for the measurement of L-lactate has been developed. The device comprises a screen-printed carbon electrode containing cobalt phthalocyanine (CoPC-SPCE), coated with lactate oxidase (LOD) that is immobilized in mesoporous silica (FSM8.0) using a polymer matrix of denatured polyvinyl alcohol; a Nafion layer on the electrode surface acts as a barrier to interferents. The sampling unit attached to the SPCE requires only a small sample volume of 100 ?L for each measurement. The measurement of l-lactate is based on the signal produced by hydrogen peroxide, the product of the enzymatic reaction. The behavior of the biosensor, LOD-FSM8.0/Naf/CoPC-SPCE, was examined in terms of pH, applied potential, sensitivity and operational range, selectivity, and storage stability. The sensor showed an optimum response at a pH of 7.4 and an applied potential of +450 mV. The determination range and the response time for L-lactate were 18.3 ?M to 1.5 mM and approximately 90s, respectively. In addition, the sensor exhibited high selectivity for L-lactate and was quite stable in storage, showing no noticeable change in its initial response after being stored for over 9 months. These results indicate that our method provides a simple, cost-effective, high-performance biosensor for l-lactate. PMID:22244144

Shimomura, Takeshi; Sumiya, Touru; Ono, Masatoshi; Ito, Tetsuji; Hanaoka, Taka-aki

2012-02-10

289

Functionalized CMK-3 mesoporous carbon with 2-amino-5-mercapto-1,3,4-thiadiazole for Hg(II) removal from aqueous media.  

PubMed

Ordered mesoporous carbon (CMK-3) was synthesized and functionalized with 2-amino-5-mercapto-1,3,4-thiadiazole groups (AMT-OCMK-3) for Hg(II) removal from aqueous solution. The modified CMK-3 was characterized by X-ray diffraction, N2 adsorption-desorption isotherm, scanning electron microscopy and Fourier transform infrared spectroscopy. The effects of solution pH, contact time, initial Hg(II) concentration and matrix effect were studied. The adsorption data were successfully fitted with the Langmuir model, exhibiting high adsorption capacity of 450.45 mg/g of AMT-OCMK-3. In the solid-phase extraction system a series of experimental parameters such as sample flow rate, sample volume, eluent volume and concentration of the eluent solution have been investigated and established for preconcentration of Hg(II) in aqueous solution. The results showed that the enrichment factor for Hg(II) was 250, the precision (relative standard deviation (RSD), %) for six replicate measurements was 2.05% and the limit of detection for Hg(II) was achieved at 0.17 ?g/L. PMID:25080004

Anbia, Mansoor; Dehghan, Roghaye

2014-07-01

290

Ionic liquids as precursors for efficient mesoporous iron-nitrogen-doped oxygen reduction electrocatalysts.  

PubMed

A ferrocene-based ionic liquid (Fe-IL) is used as a metal-containing feedstock with a nitrogen-enriched ionic liquid (N-IL) as a compatible nitrogen content modulator to prepare a novel type of non-precious-metal-nitrogen-carbon (M-N-C) catalysts, which feature ordered mesoporous structure consisting of uniform iron oxide nanoparticles embedded into N-enriched carbons. The catalyst Fe(10) @NOMC exhibits comparable catalytic activity but superior long-term stability to 20?wt?% Pt/C for ORR with four-electron transfer pathway under alkaline conditions. Such outstanding catalytic performance is ascribed to the populated Fe (Fe3 O4 ) and N (N2) active sites with synergetic chemical coupling as well as the ordered mesoporous structure and high surface area endowed by both the versatile precursors and the synthetic strategy, which also open new avenues for the development of M-N-C catalytic materials. PMID:25504819

Li, Zelong; Li, Guanglan; Jiang, Luhua; Li, Jinlei; Sun, Gongquan; Xia, Chungu; Li, Fuwei

2015-01-26

291

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

292

Gold stabilized aqueous sols immobilized on mesoporous CeO2-Al2O3 as catalysts for the preferential oxidation of carbon monoxide.  

PubMed

Nanostructured Au/Al(2)O(3)-CeO(2) catalysts with a low content of precious metal (0.9% wt.) were prepared immobilizing two different stabilized Au sols on a high surface area Al(2)O(3)-CeO(2) mixed oxide with a uniform pore size distribution, synthesized by a one-pot methodology. The samples were characterized by elemental analysis, N(2) physisorption, XRPD, TEM and (27)Al-MAS NMR techniques. The catalytic activity of the two samples in the preferential oxidation of CO in excess of H(2) (CO-PROX) was comparatively evaluated in the 35-110 degrees C temperature range. The Au-THPS/AlCe20 sample, prepared immobilizing a sol obtained reducing an aqueous solution of gold tetrachloroaurate salt with bis[tetrakis(hydroxymethyl)phosphonium sulfate], resulted very active and selective at low temperatures and its catalytic activity was correlated with the structural characteristics of the metal particles and of the ordered mesoporous support. PMID:20655539

Storaro, Loretta; Lenarda, Maurizio; Moretti, Elisa; Talon, Aldo; Porta, Francesca; Moltrasio, Bernardo; Canton, Patrizia

2010-10-15

293

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

294

Natural gas storage in activated carbon pellets without a binder  

Microsoft Academic Search

Activated carbon pellets without a binder from cellulose microcrystals as a raw material were investigated. After compression of the raw materials, the thus obtained raw material pellets were slowly carbonized to 1073 K under nitrogen. To activate them, the carbon pellets were heated to 1173 K under carbon dioxide. The activated carbon pellet shape, after heat treatment, was columnar by

K Inomata; K Kanazawa; Y Urabe; H Hosono; T Araki

2002-01-01

295

Surface heterogeneity of modified active carbons  

SciTech Connect

Active carbons were treated by oxidation and reduction conditions to control the number of functional groups on their surface. Influences of pore and surface structure of the active carbons on the energetic properties of the surface were investigated by measurements of nitrogen adsorption, heats of immersion and differential heats of adsorption. Severe oxidation brings about a decrease in specific surface area and pore volume, suggesting a partial destruction of pores. The acidic groups interact with basic molecules by acid-base interactions resulting in the evolution of high heats of adsorption and with water by hydration interaction resulting in high seat of immersion. The fractal analysis by use of molecular adsorption indicates a decrease in surface roughness with oxidation. These results suggest that active carbons become more heterogeneous with regard to surface energy distribution by oxidation, while the carbons become more homogeneous with regard to surface geometry. 30 refs., 8 figs., 5 tabs.

Tsutsumi, K.; Matsushima, Y.; Matsumoto, A. [Toyohashi Univ. of Technology, Toyohashi (Japan)

1993-10-01

296

Organic solvent regeneration of granular activated carbon  

NASA Astrophysics Data System (ADS)

The use of activated carbon for the treatment of industrial waste-streams was shown to be an effective treatment. The high costs associated with the replacement or thermal regeneration of the carbon have prohibited the economic feasibility of this process. The in situ solvent regeneration of activated carbon by means of organic solvent extraction was suggested as an economically alternative to thermal regeneration. The important aspects of the solvent regeneration process include: the physical and chemical characteristics of the adsorbent, the pore size distribution and energy of adsorption associated with the activated carbon; the degree of solubility of the adsorbate in the organic solvent; the miscibility of the organic solvent in water; and the temperature at which the generation is performed.

Cross, W. H.; Suidan, M. T.; Roller, M. A.; Kim, B. R.; Gould, J. P.

1982-09-01

297

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

2012-09-01

298

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

299

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

300

Electrospinning Synthesis and Photocatalytic Activity of Mesoporous TiO2 Nanofibers  

PubMed Central

Titanium dioxide (TiO2) nanofibers in the anatase structure were successfully prepared via electrospinning technique followed by calcination process. The morphologies, crystal structure, surface area, and the photocatalytic activity of resulting TiO2 nanofibers were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen sorption, and UV-vis spectroscopy. The results revealed that calcination temperature had greatly influenced the morphologies of TiO2 nanofibers, but no obvious effect was noticed on the crystal structure of TiO2 nanofibers. The photocatalytic properties of TiO2 nanofibers were evaluated by photocatalytic degradation of rhodamine B (RhB) in water under visible light irradiation. It was observed that TiO2 nanofibers obtained by calcination at 500°C for 3 hours exhibited the most excellent photocatalytic activity. We present a novel and simple method to fabricate TiO2 nanofibers with high-photocatalytic activity. PMID:22619598

Li, Jing; Qiao, Hui; Du, Yuanzhi; Chen, Chen; Li, Xiaolin; Cui, Jing; Kumar, Dnt; Wei, Qufu

2012-01-01

301

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

2011-01-01

302

Converting Poultry Litter into Activated Carbon  

Technology Transfer Automated Retrieval System (TEKTRAN)

Disposal of animal manure is one of the biggest problems facing agriculture today. Now new technology has been designed to covert manure into environmentally friendly and highly valued activated carbon. When pelletized and activated under specific conditions, the litter becomes a highly porous mat...

303

Adsorption of leather dye onto activated carbon prepared from bottle gourd: equilibrium, kinetic and mechanism studies.  

PubMed

Activated carbon prepared from bottle gourd has been used as adsorbent for removal of leather dye (Direct Black 38) from aqueous solution. The activated carbon obtained showed a mesoporous texture, with surface area of 556.16 m(2) g(-1), and a surface free of organic functional groups. The initial dye concentration, contact time and pH significantly influenced the adsorption capacity. In the acid region (pH 2.5) the adsorption of dye was more favorable. The adsorption equilibrium was attained after 60 min. Equilibrium data were analyzed by the Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models. The equilibrium data were best described by the Langmuir isotherm, with maximum adsorption capacity of 94.9 mg g(-1). Adsorption kinetic data were fitted using the pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models. The adsorption kinetic was best described by the second-order kinetic equation. The adsorption process was controlled by both external mass transfer and intraparticle diffusion. Activated carbon prepared from bottle gourd was shown to be a promising material for adsorption of Direct Black 38 from aqueous solution. PMID:23128640

Foletto, Edson Luiz; Weber, Caroline Trevisan; Paz, Diego Silva; Mazutti, Marcio Antonio; Meili, Lucas; Bassaco, Mariana Moro; Collazzo, Gabriela Carvalho

2013-01-01

304

Silver-loaded nitrogen-doped yolk-shell mesoporous TiO2 hollow microspheres with enhanced visible light photocatalytic activity  

NASA Astrophysics Data System (ADS)

Silver-loaded nitrogen-doped yolk-shell mesoporous TiO2 hollow microspheres (Ag-N-TiO2-YSM) were prepared by employing acetic acid as the hollowing controller and triethanolamine as the N source for the first time. Ag nanoparticles (NPs) were uniformly deposited by a simple in situ photo-reduction method, which can prevent the aggregation of Ag NPs. The efficiency of the as-prepared samples was investigated by monitoring the degradation of rhodamine B and ciprofloxacin under visible light irradiation. The experimental results indicate that N-doped yolk-shell mesoporous TiO2 hollow microspheres show higher photocatalytic activity than P25 TiO2 under visible light irradiation because of N doping and the unique yolk-shell structure. In addition, Ag-N-TiO2-YSM shows enhanced activity compared with N-TiO2-YSM due to the SPR absorption of silver NPs and the fast generation, separation and transportation of the photogenerated carriers. Moreover, the Ag contents can affect the photocatalytic activity of the Ag-N-TiO2-YSM composite. A suitable amount of Ag deposition gives the highest photocatalytic activity. A higher loading does not improve the photocatalytic activity of N-TiO2-YSM further. The active species generated in the photocatalytic system were also investigated. Based on our experimental results, a possible photocatalytic mechanism was proposed. The strategy presented here gives a promising route towards the development of delicate metal@hollow semiconductor composites for many applications in photocatalysis.Silver-loaded nitrogen-doped yolk-shell mesoporous TiO2 hollow microspheres (Ag-N-TiO2-YSM) were prepared by employing acetic acid as the hollowing controller and triethanolamine as the N source for the first time. Ag nanoparticles (NPs) were uniformly deposited by a simple in situ photo-reduction method, which can prevent the aggregation of Ag NPs. The efficiency of the as-prepared samples was investigated by monitoring the degradation of rhodamine B and ciprofloxacin under visible light irradiation. The experimental results indicate that N-doped yolk-shell mesoporous TiO2 hollow microspheres show higher photocatalytic activity than P25 TiO2 under visible light irradiation because of N doping and the unique yolk-shell structure. In addition, Ag-N-TiO2-YSM shows enhanced activity compared with N-TiO2-YSM due to the SPR absorption of silver NPs and the fast generation, separation and transportation of the photogenerated carriers. Moreover, the Ag contents can affect the photocatalytic activity of the Ag-N-TiO2-YSM composite. A suitable amount of Ag deposition gives the highest photocatalytic activity. A higher loading does not improve the photocatalytic activity of N-TiO2-YSM further. The active species generated in the photocatalytic system were also investigated. Based on our experimental results, a possible photocatalytic mechanism was proposed. The strategy presented here gives a promising route towards the development of delicate metal@hollow semiconductor composites for many applications in photocatalysis. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05963h

Jiang, Zhifeng; Wei, Wei; Mao, Danjun; Chen, Cheng; Shi, Yunfei; Lv, Xiaomeng; Xie, Jimin

2014-12-01

305

A label-free amperometric immunosensor for detection of zearalenone based on trimetallic Au-core/AgPt-shell nanorattles and mesoporous carbon.  

PubMed

A novel label-free amperometric immunosensor is proposed for the ultrasensitive detection of zearalenone (ZEN) based on mesoporous carbon (MC) and trimetallic nanorattles (core/shell particles with movable cores encapsulated in the shells). The nanorattles are composed of special Au-core and imperfect AgPt-shell structure (Au@AgPt). The Au@AgPt nanorattles are loaded onto the MC by physical adsorption. The structure of the Au@AgPt nanorattles was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Energy dispersive X-ray spectroscopy (EDS) confirmed the composition of the synthesized nanorattles. Compared with monometallic and bimetallic nanoparticles (NPs), Au@AgPt nanorattles show a higher electron transfer rate due to the synergistic effect of the Au, Ag and Pt NPs. MC further improves the sensitivity of the immunosensor because of its extraordinarily large specific surface area, suitable pore arrangement and outstanding conductivity. The large specific surface area of MC and MC@Au@AgPt were characterized by the BET method. ZEN antibodies are immobilized onto the nanorattles via Ag-NH2 bonds and Pt-NH2 bonds. Cyclic voltammetry and square wave voltammetry were used to characterize the recognizability of ZEN. Under optimum experimental conditions, the proposed immunosensor exhibited a low detection limit (1.7 pg mL(-1)), a wide linear range (from 0.005 to 15 ng mL(-1)) as well as good stability, reproducibility and selectivity. The sensor can be used in clinical analysis. PMID:25261897

Liu, Lei; Chao, Yingjun; Cao, Wei; Wang, Yulan; Luo, Chuannan; Pang, Xuehui; Fan, Dawei; Wei, Qin

2014-10-17

306

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

307

Silver-loaded nitrogen-doped yolk-shell mesoporous TiO2 hollow microspheres with enhanced visible light photocatalytic activity.  

PubMed

Silver-loaded nitrogen-doped yolk-shell mesoporous TiO2 hollow microspheres (Ag-N-TiO2-YSM) were prepared by employing acetic acid as the hollowing controller and triethanolamine as the N source for the first time. Ag nanoparticles (NPs) were uniformly deposited by a simple in situ photo-reduction method, which can prevent the aggregation of Ag NPs. The efficiency of the as-prepared samples was investigated by monitoring the degradation of rhodamine B and ciprofloxacin under visible light irradiation. The experimental results indicate that N-doped yolk-shell mesoporous TiO2 hollow microspheres show higher photocatalytic activity than P25 TiO2 under visible light irradiation because of N doping and the unique yolk-shell structure. In addition, Ag-N-TiO2-YSM shows enhanced activity compared with N-TiO2-YSM due to the SPR absorption of silver NPs and the fast generation, separation and transportation of the photogenerated carriers. Moreover, the Ag contents can affect the photocatalytic activity of the Ag-N-TiO2-YSM composite. A suitable amount of Ag deposition gives the highest photocatalytic activity. A higher loading does not improve the photocatalytic activity of N-TiO2-YSM further. The active species generated in the photocatalytic system were also investigated. Based on our experimental results, a possible photocatalytic mechanism was proposed. The strategy presented here gives a promising route towards the development of delicate metal@hollow semiconductor composites for many applications in photocatalysis. PMID:25434570

Jiang, Zhifeng; Wei, Wei; Mao, Danjun; Chen, Cheng; Shi, Yunfei; Lv, Xiaomeng; Xie, Jimin

2014-12-11

308

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

NASA Astrophysics Data System (ADS)

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.

Oh, Seung-Lim; Choi, Kyong-Hoon; Im, Ji-Eun; Wang, Kang-Kyun; Yaung, Hae-Yong; Kim, Kyungkon; Kim, Yong-Rok

2011-07-01

309

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

2011-07-01

310

Mesoporous NiCo2S4 nanoparticles as high-performance electrode materials for supercapacitors  

NASA Astrophysics Data System (ADS)

Mesoporous NiCo2S4 nanoparticles prepared through solvothermal route are reported as remarkable supercapacitor electrode materials. The resulting samples are characterized by means of XRD, FSEM, TEM, HRTEM, SAED, EDS and BET. With large specific surface area, superior mesopore structure and high electronic conductivity, the as-obtained NiCo2S4 nanoparticles manifest excellent electrochemical performances with ultrahigh specific capacitance (1440 F g-1 at 3 A g-1) after 250 cycles, exceptional rate capability (75.1% capacity retention from 2 to 50 A g-1) and good cycling stability (107.9% of initial capacity retention for 1000 cycles). Additionally, an asymmetric supercapacitor utilising the mesoporous NiCo2S4 nanoparticles as a positive electrode and activated carbon as a negative electrode is further fabricated, which exhibits a prominent energy density of 28.3 Wh kg-1 at a power density of 245 W kg-1 and superior cycling stability of 91.7% initial capacity retention over 5000 cycles. These results above demonstrate the great potential of mesoporous NiCo2S4 nanoparticles in the development of high-performance electrode materials for supercapacitors.

Zhu, Yirong; Wu, Zhibin; Jing, Mingjun; Yang, Xuming; Song, Weixin; Ji, Xiaobo

2015-01-01

311

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

312

Interactions of Plutonium and Lanthanides with Ordered Mesoporous Materials  

NASA Astrophysics Data System (ADS)

Ordered mesoporous materials are porous solids with a regular, patterned structure composed of pores between 2 and 50 nm wide. Such materials have attracted much attention in the past twenty years because the chemistry of their synthesis allows control of their unique physicochemical properties, which can be tuned for a variety of applications. Generally, ordered mesoporous materials have very high specific surface areas and pore volumes, and offer unique structures that are neither crystalline nor amorphous. The large tunable interface provided by ordered mesoporous solids may be advantageous in applications involving sequestration, separation, or detection of actinides and lanthanides in solution. However, the fundamental chemical interactions of actinides and lanthanides must be understood before applications can be implemented. This dissertation focuses primarily on the fundamental interactions of plutonium with organically modified mesoporous silica, as well as several different porous carbon materials, both untreated and chemically oxidized. A method for functionalizing mesoporous silica by self assembly and molecular grafting of functional organosilane ligands was optimized for the 2D-hexagonal ordered mesoporous silica known as SBA-15 (Santa Barbara amorphous silica). Four different organically-modified silica materials were synthesized and characterized with several techniques. To confirm that covalent bonds were formed between the silane anchor of the ligand and the silica substrate, functionalized silica samples were analyzed with 29Si nuclear magnetic resonance spectroscopy. Infrared spectroscopy was used in combination with 13C and 31P nuclear magnetic resonance spectroscopy to verify the molecular structures of the ligands after they were synthesized and grafted to the silica. The densities of the functional silane ligands on the silica surface were estimated using thermogravimetric analysis. Batch sorption experiments were conducted with solutions of Pu(IV), Pu(VI), Eu(III), Ce(III), and Zr(IV). The acetamide phosphonate functionalized silica called Ac-Phos-SBA-15 required more extensive synthesis than the other three functionalized silica materials. Development of functionalized mesoporous silica extractants for actinides is contingent on their synthesis and hydrolytic stability, and these two aspects of the Ac-Phos-SBA-15 material are discussed. This material showed the highest binding affinity for all of the target ions, and the sorption and desorption of Pu(VI) to Ac-Phos-SBA-15 was extensively investigated. Ordered mesoporous carbons are attractive as sorbents because of their extremely high surface areas and large pore volumes, and could be suitable substrates for the development of actinide sensors based on their electrochemical properties. Three different mesoporous carbon materials were synthesized by collaborators to test their application as radionuclide sorbent materials. The first is called CMK (carbons mesostructured by Korea Advanced Institute of Science and Technology), and was synthesized using a hard silica template with 3D-bicontinuous ordered mesostructure. Highly ordered body-centered cubic mesoporous carbon was synthesized by self-assembly of a phenol resin around a soft polymer template, and this material is known as FDU-16 (Fudan University). Etching of the silica portion of mesoporous carbon-silica composites created the 2D-hexagonal mesoporous carbon called C-CS (carbon from carbon-silica nanocomposites) with a bimodal pore size distribution. The as-synthesized nanocast mesoporous carbon in this work is called UN CMK, and the same material after oxidation treatment with nitric acid is called OX CMK. A portion of both FDU-16-type and C-CS-type ordered mesoporous carbons were oxidized with acidic ammonium persulfate, which created the oxidized carbon materials called FDU-16-COOH and C-CS-COOH, respectively. The mesoporous carbons were characterized by scanning electron microscopy to view their particle sizes and morphologies. Their porosities and structures on the meso-scale were an

Parsons-Moss, Tashi

313

Flow cytometry-assisted mix-and-read assay for ultrasensitive detection of protein kinase activity by use of Zr(4+)-functionalized mesoporous SiO2 microspheres.  

PubMed

A flow cytometry-assisted mix-and-read assay is developed for ultrasensitive detection of protein kinase activity by use of Zr(4+)-functionalized mesoporous SiO2 microspheres (ZrMMs). This strategy integrates the distinct advantages of ZrMMs for highly specific recognition as well as high capacity binding of kinase-induced fluorescent phosphopeptides and flow cytometry for powerful and separation-free bead analysis, leading to an ultrahigh sensitivity for kinase analysis in a extremely simple mix-and-read manner. Furthermore, this ultrasensitive design is well suitable for detection of cell kinase activities in complex biological samples and for screening of potential protein kinase inhibitors, which is of great significance for the development of targeted therapy, clinical diagnosis, and studies of cellular signal transduction pathways. PMID:24138701

Ren, Wei; Liu, Chenghui; Lian, Sai; Li, Zhengping

2013-11-19

314

Design and Fabrication of Hierarchically Porous Carbon with a Template-free Method  

NASA Astrophysics Data System (ADS)

Fabrication of hierarchically porous carbon materials (HPCs) with high surface area and pore volume has always been pursued. However, the currently effective template methods and acid/base activation strategies suffer from the drawbacks of either high costs or tedious steps. Herein, HPCs with 3D macro-mesopores and short-range meso-micropores were fabricated via an easy and sustainable two-step method from biomass. Macro-mesopores were constructed by slightly accumulation/aggregation of carbon spheres ranging from 60 nm to 80 nm, providing efficient mass diffusion pathways. Short-range mesopores and micropores with high electrolyte accessibility were developed in these spheres by air activation. The obtained HPCs showed surface area values up to 1306 m2/g and high mesopore volume proportion (63.9%). They demonstrated excellent capacitance and low equivalent series resistance (ESR) as supercapacitor electrode materials, suggesting the efficient diffusion and adsorption of electrolyte ions in the designed hierarchically porous structure.

Gong, Yutong; Wei, Zhongzhe; Wang, Jing; Zhang, Pengfei; Li, Haoran; Wang, Yong

2014-09-01

315

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

316

High-temperature-stable and regenerable catalysts: platinum nanoparticles in aligned mesoporous silica wells.  

PubMed

We report the synthesis, structural characterization, thermal stability study, and regeneration of nanostructured catalysts made of 2.9 nm Pt nanoparticles sandwiched between a 180 nm SiO2 core and a mesoporous SiO2 shell. The SiO2 shell consists of 2.5 nm channels that are aligned perpendicular to the surface of the SiO2 core. The nanostructure mimics Pt nanoparticles that sit in mesoporous SiO2 wells (Pt@MSWs). By using synchrotron-based small-angle X-ray scattering, we were able to prove the ordered structure of the aligned mesoporous shell. By using high-temperature cyclohexane dehydrogenation as a model reaction, we found that the Pt@MSWs of different well depths showed stable activity at 500 °C after the induction period. Conversely, a control catalyst, SiO2 -sphere-supported Pt nanoparticles without a mesoporous SiO2 shell (Pt/SiO2 ), was deactivated. We deliberately deactivated the Pt@MSWs catalyst with a 50 nm deep well by using carbon deposition induced by a low H2 /cyclohexane ratio. The deactivated Pt@MSWs catalyst was regenerated by calcination at 500 °C with 20 % O2 balanced with He. After the regeneration treatments, the activity of the Pt@MSWs catalyst was fully restored. Our results suggest that the nanostructured catalysts-Pt nanoparticles confined inside mesoporous SiO2 wells-are stable and regenerable for treatments and reactions that require high temperatures. PMID:24039118

Xiao, Chaoxian; Maligal-Ganesh, Raghu V; Li, Tao; Qi, Zhiyuan; Guo, Zhiyong; Brashler, Kyle T; Goes, Shannon; Li, Xinle; Goh, Tian Wei; Winans, Randall E; Huang, Wenyu

2013-10-01

317

High-Temperature-Stable and Regenerable Catalysts: Platinum Nanoparticles in Aligned Mesoporous Silica Wells  

SciTech Connect

We report the synthesis, structural characterization, thermal stability study, and regeneration of nanostructured catalysts made of 2.9?nm Pt nanoparticles sandwiched between a 180?nm SiO2 core and a mesoporous SiO2 shell. The SiO2 shell consists of 2.5?nm channels that are aligned perpendicular to the surface of the SiO2 core. The nanostructure mimics Pt nanoparticles that sit in mesoporous SiO2 wells (Pt@MSWs). By using synchrotron-based small-angle X-ray scattering, we were able to prove the ordered structure of the aligned mesoporous shell. By using high-temperature cyclohexane dehydrogenation as a model reaction, we found that the Pt@MSWs of different well depths showed stable activity at 500?°C after the induction period. Conversely, a control catalyst, SiO2-sphere-supported Pt nanoparticles without a mesoporous SiO2 shell (Pt/SiO2), was deactivated. We deliberately deactivated the Pt@MSWs catalyst with a 50?nm deep well by using carbon deposition induced by a low H2/cyclohexane ratio. The deactivated Pt@MSWs catalyst was regenerated by calcination at 500?°C with 20?% O2 balanced with He. After the regeneration treatments, the activity of the Pt@MSWs catalyst was fully restored. Our results suggest that the nanostructured catalysts—Pt nanoparticles confined inside mesoporous SiO2 wells—are stable and regenerable for treatments and reactions that require high temperatures.

Xiao, Chaoxian [Ames Laboratory; Maligal-Ganesh, Raghu V. [Ames Laboratory; Li, Tao [Argonne Laboratory; Wi, Zhiyuan [Ames Laboratory; Guo, Zhiyong [Ames Laboratory; Brashler, Kyle T. [Ames Laboratory; Goes, Shannon [Ames Laboratory; Li, Xinle [Ames Laboratory; Goh, Tian Wei [Ames Laboratory; Winans, Randall E. [Argonne Laboratory; Huang, Wenyu [Ames Laboratory

2013-08-22

318

Granular Activated Carbon Filter-Adsorber Systems  

Microsoft Academic Search

The design, operation, and performance of granular activated carbon (GAC) filter-adsorbers were documented and potential problems were identified by means of a survey of operating plants and a review of the literature. It was found that GAC as a total or partial replacement for sand is as effective as conventional filtration media for removing turbidity, provided an appropriate medium size

Sandra L. Graese; Vernon L. Snoeyink; Ramon G. Lee

1987-01-01

319

Nanoscaled palladium catalysts on activated carbon support  

Microsoft Academic Search

The application of nanosized palladium catalysts has gained growing importance over the last few years. Palladiumbased catalytic methods for fine organic synthesis permits the replacement of traditional labor-consuming techniques in multi-step organic syntheses and provides an improvement from the standpoint of cost and environmental impact. The use of activated carbon \\

I. Simakova; A. Koskin; I. Deliy; A. Simakov

2005-01-01

320

MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON  

EPA Science Inventory

The paper presents a mathematical model of total mercury removed from the flue gas at coal-fired plants equipped with powdered activated carbon (PAC) injection for Mercury control. The developed algorithms account for mercury removal by both existing equipment and an added PAC in...

321

Preparation and textural characterisation of activated carbon from vine shoots ( Vitis vinifera) by H 3PO 4—Chemical activation  

NASA Astrophysics Data System (ADS)

An abundant and low-cost agricultural waste as vine shoots ( Vitis vinifera) (VS), which is generated by the annual pruning of vineyards, has been used as raw material in the preparation of powder activated carbon (AC) by the method of chemical activation with phosphoric acid. After size reduction, VS were impregnated for 2 h with 60 wt.% H 3PO 4 solution at room temperature, 50 and 85 °C. The three impregnated products were carbonised at 400 °C. The product impregnated at 50 °C was heated either first at 150-250 °C and then at 400 °C or simply at 350-550 °C in N 2 atmosphere. The time of isothermal treatment after each dynamic heating was 2 h. The carbons were texturally characterised by gas adsorption (N 2, -196 °C), mercury porosimetry, and density measurements. FT-IR spectroscopy was also applied. Better developments of surface area and microporosity are obtained when the impregnation of VS with the H 3PO 4 solution is effected at 50 °C and for the products heated isothermally at 200 and 450 °C. The mesopore volume is also usually higher for the products impregnated and heated at intermediate temperatures.

Corcho-Corral, B.; Olivares-Marín, M.; Fernández-González, C.; Gómez-Serrano, V.; Macías-García, A.

2006-06-01

322

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

323

Adsorption behavior of activated carbon derived from pyrolusite-modified sewage sludge: equilibrium modeling, kinetic and thermodynamic studies.  

PubMed

Activated carbon was developed from sewage sludge using pyrolusite as an additive. It was demonstrated that the removal efficiency of two synthetic dyes (Tracid orange GS and Direct fast turquoise blue GL) by the produced adsorbent was up to 97.6%. The activated carbon with pyrolusite addition had 38.2% higher surface area, 43.8% larger micropore and 54.4% larger mesopore production than ordinary sludge-based activated carbons. Equilibrium adsorption isotherms and kinetics were also investigated based on dyes adsorption tests. The experimental data were analyzed by the Langmuir and Freundlich models of adsorption, and the results fitted well to the Langmuir isotherm. The kinetic data have been analyzed using pseudo-first-order, pseudo-second-order and intraparticle diffusion equation. The experimental data fitted very well with pseudo-second-order kinetic model. Activation energies for the adsorption processes ranged between 8.7 and 19.1 kJ mol 1. Thermodynamic parameters such as standard free energy (deltaG0), standard enthalpy (deltaH0) and standard entropy (deltaS0) were evaluated. The adsorption of these two dyes on the activated carbon was found to be a spontaneous and endothermic process in nature. PMID:22097045

Chen, Yao; Jiang, Wenju; Jiang, Li; Ji, Xiujuan

2011-01-01

324

Characterization of Dispersed Heteropoly Acid on Mesoporous Zeolite Using Solid-State P-31 NMR Spin-Lattice Relaxation  

SciTech Connect

Dispersion and quantitative characterization of supported catalysts is a grand challenge in catalytic science. In this paper, heteropoly acid H3PW12O40 (HPA) is dispersed on mesoporous zeolite silicalite-1 derived from hydrothermal synthesis using carbon black nanoparticle templates, and the catalytic activity is studied for 1-butene isomerization. The HPAs supported on conventional zeolite and on mesoporous zeolite exhibit very different activities and thus provide good model systems to investigate the structure dependence of the catalytic properties. The HPA on mesoporous silicalite-1 shows enhanced catalytic activity for 1-butene isomerization, while HPA on conventional silicalite-1 exhibits low activity. To elucidate the structural difference, supported HPA catalysts are characterized using a variety of techniques, including 31P magic angle spinning nuclear magnetic resonance, and are shown to contain a range of species on both mesoporous and conventional zeolites. However, contrary to studies reported in the literature, conventional NMR techniques and chemical shifts alone do not provide sufficient information to distinguish the dispersed and aggregated surface species. The dispersed phase and the nondispersed phase can only be unambiguously and quantitatively characterized using spin-lattice relaxation NMR techniques. The HPA supported on mesoporous zeolite contains a fast relaxation component related to the dispersed catalyst, giving a much higher activity, while the HPA supported on conventional zeolite has essentially only the slow relaxation component with very low activity. The results obtained from this work demonstrate that the combination of spinning sideband fitting and spin-lattice relaxation techniques can provide detailed structural information on not only the Keggin structure for HPA but also the degree of dispersion on the support.

Zhu, Kake; Hu, Jian Z.; She, Xiaoyan; Liu, Jun; Nie, Zimin; Wang, Yong; Peden, Charles HF; Kwak, Ja Hun

2009-09-01

325

Ultrafine single-crystal TiOF2 nanocubes with mesoporous structure, high activity and durability in visible light driven photocatalysis  

NASA Astrophysics Data System (ADS)

Single crystal TiOF2 nanocubes assembled into a mesoporous structure were synthesized by alcoholysis of TiF4 under solvothermal conditions, which displayed spectral response in the visible area owing to the intrinsic narrow energy band gap. Mechanism studies revealed that TiOF2 was formed via consecutive hydrolysis reactions and the H2O produced by condensation between two alcohols played a key role in determining the TiOF2 crystal growth and its transformation to anatase TiO2. The TiOF2 nanocube size could be easily adjusted by changing either alcoholysis time, or solvothermal temperature, or alcohol kind owing to the different H2O production rate and amount. The small-sized TiOF2 nanocubes with large surface area exhibited high activity in photocatalytic degradation of Rhodamine B (RhB) and 4-chlorophenol (4-CP) owing to the enhanced adsorption for reactant molecules and the reduced photoelectron-hole recombination rate. Meanwhile, they also showed strong durability since the mesoporous structure enhanced the stability against either the phase transformation from TiOF2 crystal to anatase TiO2 or the agglomeration of TiOF2 nanocubes.Single crystal TiOF2 nanocubes assembled into a mesoporous structure were synthesized by alcoholysis of TiF4 under solvothermal conditions, which displayed spectral response in the visible area owing to the intrinsic narrow energy band gap. Mechanism studies revealed that TiOF2 was formed via consecutive hydrolysis reactions and the H2O produced by condensation between two alcohols played a key role in determining the TiOF2 crystal growth and its transformation to anatase TiO2. The TiOF2 nanocube size could be easily adjusted by changing either alcoholysis time, or solvothermal temperature, or alcohol kind owing to the different H2O production rate and amount. The small-sized TiOF2 nanocubes with large surface area exhibited high activity in photocatalytic degradation of Rhodamine B (RhB) and 4-chlorophenol (4-CP) owing to the enhanced adsorption for reactant molecules and the reduced photoelectron-hole recombination rate. Meanwhile, they also showed strong durability since the mesoporous structure enhanced the stability against either the phase transformation from TiOF2 crystal to anatase TiO2 or the agglomeration of TiOF2 nanocubes. Electronic supplementary information (ESI) available: Details of the FESEM images, TEM images, N2 adsorption-desorption isotherm, FTIR spectra, TG analysis, XRD patterns, UV-Vis spectra, and model of TiOF2 cubic single crystal cell. See DOI: 10.1039/c3nr04489k

Wang, Jinguo; Cao, Fenglei; Bian, Zhenfeng; Leung, Michael K. H.; Li, Hexing

2013-12-01

326

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. PMID:22259762

Vernimmen, Jarian; Cool, Pegie

2011-01-01

327

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

328

Solid acid catalysts from clays: preparation of mesoporous catalysts by chemical activation of metakaolin under acid conditions.  

PubMed

Natural kaolin was treated at 850 or 950 degrees C in air flow to give respectively the metakaolin samples MK8 and MK9. The obtained materials were successively treated at 90 degrees C with a 1 M solution of H(2)SO(4), for various time lengths. The acid treatment of MK8 was found to give a high surface area microporous material with good catalytic properties related to the high density of acid sites, while MK9 gave an ordered mesoporous material with a low density of acid sites. The materials were characterized by several techniques, X-ray powder diffraction, thermogravimetric analysis, N(2) physisorption, scanning electron microscopy, and temperature-programmed desorption of ammonia. The 1-butene isomerization was used as test reaction to evaluate the acidity of the samples. PMID:17451736

Lenarda, M; Storaro, L; Talon, A; Moretti, E; Riello, P

2007-07-15

329

Adsorption of chlorophenols on granular activated carbon  

SciTech Connect

Studies were undertaken of the adsorption of chlorinated phenols from aqueous solution on granular activated carbon (Filtrasorb-400, 30 x 40 mesh). Single-component equilibrium adsorption data on the eight compounds in two concentration ranges at pH 7.0 fit the Langmuir equation better than the Freundlich equation. The adsorptive capacities at pH 7.0 increase from pentachlorophenol to trichlorophenols and are fairly constant from trichlorophenols to monochlorophenols. The adsorption process was found to be exothermic for pentachlorophenol and 2,4,6-trichlorophenol, and endothermic for 2,4-dichlorophenol and 4-chlorophenol. Equilibrium measurements were also conducted for 2,4,5-trichlorophenol, 2,4-dichlorophenol, and 4-chlorophenol over a wide pH range. A surface complexation model was proposed to describe the effect of pH on adsorption equilibria of chlorophenols on activated carbon. The simulations of the model are in excellent agreement with the experimental data. Batch kinetics studies were conducted of the adsorption of chlorinated phenols on granular activated carbon. The results show that the surface reaction model best describes both the short-term and long-term kinetics, while the external film diffusion model describes the short-term kinetics data very well and the linear-driving-force approximation improved its performance for the long-term kinetics. Multicomponent adsorption equilibria of chlorophenols on granular activated carbon was investigated in the micromolar equilibrium concentration range. The Langmuir competitive and Ideal Adsorbed Solution (IAS) models were tested for their performance on the three binary systems of pentachlorophenol/2,4,6-trichlorophenol, 2,4,6-trichlorophenol/2,4-dichlorophenol, and 2,4-dichlorophenol/4-chlorophenol, and the tertiary system of 2,4,6-trichlorophenol/2,4-dichlorophenol/4-chlorophenol, and found to fail to predict the two-component adsorption equilibria of the former two binary systems and the tertiary system.

Yang, M.

1993-12-31

330

Sorption of heavy metal cations on activated carbon  

Microsoft Academic Search

Activated carbon is used to remove trace amounts of organic compounds from waters and wastewaters. An experimental program was conducted to determine the kinetics of sorption of lead, copper, and zinc on the surface of the powdered activated carbon Nuchar SA, and on granular activated carbon Filtrasorb 400. The results of the experimental program showed that sorption of heavy metals

Wilczak

1988-01-01

331

Dynamic adsorption of radon by activated carbon.  

PubMed

The adsorption of radon on activated carbon has been used in or considered for a number of applications, including in situ decay beds, cyclic decontamination systems, and diffusive samplers. And although there are numerous measurements of the adsorption coefficients of specific activated carbons for radon, each of these applications depends on knowing, in addition to the adsorption coefficient for radon, the mass transfer factors describing its dynamic adsorption. Here we used a standard procedure in gas chromatography and chemical engineering, the spreading of a pulse as it passes through a bed of adsorbent, to determine these mass transfer factors. For this application, this procedure is developed further to correct the radon adsorption data for distortions caused by the decay of radon and by the presence of radon decay products in the detector. The results from eight activated carbons show a wide variation in the mass transfer coefficients for radon, which could affect significantly the suitability of adsorbents, as demonstrated here by the effect that mass transfer has on the performance of in situ decay beds. PMID:15761299

Gaul, Wayne C; Underhill, Dwight W

2005-04-01

332

High-performance electrocatalysts for oxygen reduction derived from cobalt porphyrin-based conjugated mesoporous polymers.  

PubMed

A cobalt-nitrogen-doped porous carbon that exhibits a ribbon-shape morphology, high surface area, mesoporous structure, and high nitrogen and cobalt content is fabricated for high-performance self-supported oxygen reduction electrocatalytsts through template-free pyrolysis of cobalt porphyrin-based conjugated mesoporous polymer frameworks. PMID:24293313

Wu, Zhong-Shuai; Chen, Long; Liu, Junzhi; Parvez, Khaled; Liang, Haiwei; Shu, Jie; Sachdev, Hermann; Graf, Robert; Feng, Xinliang; Müllen, Klaus

2014-03-01

333

An ordered mesoporous organosilica hybrid material with a crystal-like wall structure  

Microsoft Academic Search

Surfactant-mediated synthesis strategies are widely used to fabricate ordered mesoporous solids in the form of metal oxides, metals, carbon and hybrid organosilicas. These materials have amorphous pore walls, which could limit their practical utility. In the case of mesoporous metal oxides, efforts to crystallize the framework structure by thermal and hydrothermal treatments have resulted in crystallization of only a fraction

Shinji Inagaki; Shiyou Guan; Tetsu Ohsuna; Osamu Terasaki

2002-01-01

334

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

SciTech Connect

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 nm to the existing mesopores without deterioration of the integrity of the original mesoporous carbon. Elemental sulfur has been loaded to the micropores through a solution infiltration method. The resulted S/C composites with various loading level of sulfur have a high surface areas and large internal porosities. These materials have been tested as novel cathodes for Li/S batteries. The results show that the cyclability and the utilization of sulfur in the Li/S batteries have been significantly improved. The large internal porosity and surface area of the micro-mesoporous carbon is essential for retaining sulfur in the cathode and therefore maximizing the capacity and lifespan of the cathode.

Liang, Chengdu [ORNL] [ORNL; Dudney, Nancy J [ORNL] [ORNL; Howe, Jane Y [ORNL] [ORNL

2009-01-01

335

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

336

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

337

Entrapment of Carbon Dioxide in the Active Site of Carbonic Anhydrase II*  

E-print Network

Entrapment of Carbon Dioxide in the Active Site of Carbonic Anhydrase II* Received for publication step of CO2 hydration catalyzed by the zinc- metalloenzyme human carbonic anhydrase II, the binding substrates and revealing hydrophobic pockets in proteins. Since their discovery (2), the carbonic anhydrases

Gruner, Sol M.

338

Gyroidal mesoporous multifunctional nanocomposites via atomic layer deposition  

NASA Astrophysics Data System (ADS)

We demonstrate the preparation of rationally designed, multifunctional, monolithic and periodically ordered mesoporous core-shell nanocomposites with tunable structural characteristics. Three-dimensionally (3D) co-continuous gyroidal mesoporous polymer monoliths are fabricated from a solution-based triblock terpolymer-resol co-assembly and used as the functional templates for the fabrication of free-standing core-shell carbon-titania composites using atomic layer deposition (ALD). The deposition depth into the torturous gyroidal nanonetwork is investigated as a function of ALD conditions and the resulting composites are submitted to different thermal treatments. Results suggest that ALD can homogenously coat mesoporous templates with well defined pore sizes below 50 nm and thicknesses above 10 ?m. Structural tunability like titania shell thickness and pore size control is demonstrated. The ordered nanocomposites exhibit triple functionality; a 3D continuous conductive carbon core that is coated with a crystalline titania shell that in turn is in contact with a 3D continuous mesopore network in a compact monolithic architecture. This materials design is of interest for applications including energy conversion and storage. Gyroidal mesoporous titania monoliths can be obtained through simultaneous titania crystallization and template removal in air.We demonstrate the preparation of rationally designed, multifunctional, monolithic and periodically ordered mesoporous core-shell nanocomposites with tunable structural characteristics. Three-dimensionally (3D) co-continuous gyroidal mesoporous polymer monoliths are fabricated from a solution-based triblock terpolymer-resol co-assembly and used as the functional templates for the fabrication of free-standing core-shell carbon-titania composites using atomic layer deposition (ALD). The deposition depth into the torturous gyroidal nanonetwork is investigated as a function of ALD conditions and the resulting composites are submitted to different thermal treatments. Results suggest that ALD can homogenously coat mesoporous templates with well defined pore sizes below 50 nm and thicknesses above 10 ?m. Structural tunability like titania shell thickness and pore size control is demonstrated. The ordered nanocomposites exhibit triple functionality; a 3D continuous conductive carbon core that is coated with a crystalline titania shell that in turn is in contact with a 3D continuous mesopore network in a compact monolithic architecture. This materials design is of interest for applications including energy conversion and storage. Gyroidal mesoporous titania monoliths can be obtained through simultaneous titania crystallization and template removal in air. Electronic supplementary information (ESI) available: Photographs of flexible templates and the Beneq ALD reactor indicating the different sample positioning. See DOI: 10.1039/c4nr01948b

Werner, Jörg G.; Scherer, Maik R. J.; Steiner, Ullrich; Wiesner, Ulrich

2014-07-01

339

Potential of activated carbon from waste rubber tire for the adsorption of phenolics: effect of pre-treatment conditions.  

PubMed

Rubber tire activated carbon modification (RTACMC) and rubber tire activated carbon (RTAC) were prepared from waste rubber tire by microwave assisted chemical treatment and physical heating respectively. A greater improvement in porosity and total pore volume was achieved in RTACMC as compared to that of RTAC. But both have a predominantly mesoporous structure. Under identical operating conditions, an irradiation time of 10 min, chemical impregnation ratio of 1.50 and a microwave power of 600 W resulted in maximizing the efficiency of RTACMC for p-cresol (250 mg/g) at a contact time of 90 min while RTAC showed a 71.43 mg/g adsorption capacity at 150 min. Phenol, due to its higher solubility was adsorbed to a lesser extent by both adsorbents. Physical nature of interactions, pore diffusion mechanism and exothermicity of the adsorption process was operative in both adsorbents. The outcomes support the feasibility of preparing high quality activated carbon from waste rubber tire by microwave assisted chemical activation. PMID:24407705

Gupta, Vinod Kumar; Nayak, Arunima; Agarwal, Shilpi; Tyagi, Inderjeet

2014-03-01

340

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, Wu; Borong, Bao; Ruimin, Zhou; Jinliang, Zhu; Longxin, Hu

1998-10-01

341

Histochemical demonstration of carbonic anhydrase activity  

Microsoft Academic Search

Freeze-dried frozen sections are floated on the surface of the freshly prepared incubation mixture (CoSO4 1.75 × 10-3M, H2SO4 5.3 × 10-2M, NaHCO3 1.57 × 10-2M and KH2PO4 1.17 to 11.7 × 10-3M; demonstration of weak activity requires high phosphate). A compound containing cobalt and phosphorous precipitates at carbonic anhydrase sites and is converted to CoS. Adequate staining requires only

Holger P. J. Hansson

1967-01-01

342

Charcoal and activated carbon at elevated pressure  

SciTech Connect

High quality charcoal has been produced with very high yields of 50% to 60% from macadamia nut and kukui nut shells and of 44% to 47% from Eucalyptus and Leucaena wood in a bench scale unit at elevated pressure on a 2 to 3 hour cycle, compared to commercial practice of 25% to 30% yield on a 7 to 12 day operating cycle. Neither air pollution nor tar is produced by the process. The effects of feedstock pretreatments with metal additives on charcoal yield are evaluated in this paper. Also, the influences of steam and air partial pressure and total pressure on yields of activated carbon from high yield charcoal are presented.

Antal, M.J. Jr.; Dai, Xiangfeng; Norberg, N. [Univ. of Hawaii at Manoa, Honolulu, HI (United States)] [and others

1995-12-01

343

Adsorbed natural gas storage with activated carbon  

SciTech Connect

Despite technical advances to reduce air pollution emissions, motor vehicles still account for 30 to 70% emissions of all urban air pollutants. The Clean Air Act Amendments of 1990 require 100 cities in the United States to reduce the amount of their smog within 5 to 15 years. Hence, auto emissions, the major cause of smog, must be reduced 30 to 60% by 1998. Natural gas con be combusted with less pollutant emissions. Adsorbed natural gas (ANG) uses adsorbents and operates with a low storage pressure which results in lower capital costs and maintenance. This paper describes the production of an activated carbon adsorbent produced from an Illinois coal for ANG.

Sun, Jian; Brady, T.A.; Rood, M.J. [Univ. of Illinois, Urbana, IL (United States)] [and others

1996-12-31

344

Two-dimensional hybrid mesoporous Fe2O3-graphene nanostructures: a highly active and reusable peroxidase mimetic toward rapid, highly sensitive optical detection of glucose.  

PubMed

In this article, for the first time, two-dimensional hybrid mesoporous Fe2O3-graphene (mFe2O3-G) nanostructures were developed as a peroxidase mimetic with catalytic activities superior to those of mFe2O3, G, and previously reported Fe-based peroxidase mimetics. The high-surface-area mFe2O3 not only offers a large number of catalytically active sites, but also facilitates the diffusion of 3,3,5,5-tetramethylbenzidine (TMB) and H2O2 toward G surface. On the other hand, G is ?-rich and thus favors the adsorption and enrichment of TMB within these pores. These synergistic effects lead to highly improved catalytic performances. Based on these findings, a simple, rapid, and highly sensitive and selective optical detector of glucose has been developed and demonstrated in buffer solution with a pretty low detection limit of 0.5 ?M. In addition, this nanosensor is reusable and can also be used for glucose detection in diluted serum. PMID:24094524

Xing, Zhicai; Tian, Jingqi; Asiri, Abdullah M; Qusti, Abdullah H; Al-Youbi, Abdulrahman O; Sun, Xuping

2014-02-15

345

Preparation of activated carbons from bituminous coal pitches  

NASA Astrophysics Data System (ADS)

High-porosity carbons were prepared from bituminous coal pitches by combining chemical and physical activation. The chemical activation process consisted of potassium hydroxide impregnation followed by carbonization in nitrogen atmosphere. The effect of the KOH impregnation ratio on the surface area and pore volumes evolution of the carbons derived from mesophase pitch was studied. The optimum KOH:pitch ratio was fixed to realize a physical activation process in order to increase the textural parameters of the KOH-activated carbons. Physical activation was performed by carbonizing the KOH-activated carbons followed by gasifying with air. The influence of the carbonization temperature and the residence time of the gasification with air were explored to optimize those preparation parameters.

Gañan, J.; González-Garc?´a, C. M.; González, J. F.; Sabio, E.; Mac?´as-Garc?´a, A.; D?´az-D?´ez, M. A.

2004-11-01

346

DISINFECTION OF BACTERIA ATTACHED TO GRANULAR ACTIVATED CARBON  

EPA Science Inventory

Heterotrophic plate count bacteria, coliform organisms, and pathogenic microorganisms attached to granular activated carbon (GAC) particles were examined for their susceptibility to chlorine disinfection. When these bacteria were grown on carbon particles and then disinfected wit...

347

Research on forest carbon pool and carbon release by human activity of Tanjiang River Basin  

Microsoft Academic Search

We researched the relation between forest carbon pool and human activity carbon release of Tanjiang river basin, the finding is: (1)Since 1990, Forest of Tanjiang river basin always act as carbon sink, and the forest carbon sink is more and more obvious. Forest absorbed carbon is 1057.90×10 4 t in 1990, and in 2002, the amount is 1280.61×10 4 t,

Chen Zhiliang; Wu Zhifeng; Liu Xulong; Cheng Jiong; Liu Ping; Xia Nianhe

2005-01-01

348

Reduction of bromate by granular activated carbon  

SciTech Connect

Ozonation of waters containing bromide can lead to the formation of bromate, a probable human carcinogen. Since bromate will be regulated at 10 {micro}g/L by the Stage 1 Disinfectants/Disinfection By-Products Rule, there is considerable interest in finding a suitable method of bromate reduction. Granular activated carbon (GAC) can be used to chemically reduce bromate to bromide, but interference from organic matter and anions present in natural water render this process inefficient. In an effort to improve bromate reduction by GAC, several modifications were made to the GAC filtration process. The use of a biologically active carbon (BAC) filter ahead of a fresh GAC filter with and without preozonation, to remove the biodegradable organic matter, did not substantially improve the bromate removal of the GAC filter. The use of the BAC filter for biological bromate reduction proved to be the most encouraging experiment. By lowering the dissolved oxygen in the influent to the BAC from 8.0 mg/L to 2.0 mg/L, the percent bromate removal increased from 42% to 61%.

Kirisits, M.J.; Snoeyink, V.L.; Kruithof, J.C.

1998-07-01

349

Mesoporous silica-assisted carbon free Li2MnSiO4 cathode nanoparticles for high capacity Li rechargeable batteries.  

PubMed

Porous and spherical Li2MnSiO4 nanoparticles have been synthesized through a facile sol-gel route via a mesoporous silica template. Galvanostatic charge-discharge of the resultant Li2MnSiO4 cathode exhibits enhanced charge-discharge capacity relative to that of particles prepared by the conventional sol-gel process, up to 25% in discharge capacity, even without any particulate process such as milling with conductive agents. The standout electrochemical performance could be attributed to the unique high surface-to-volume ratio, porous geometry and improved accommodation of transformation strains during the electrochemical lithiation-delithiation process. PMID:24343226

Kim, Sue Jin; Suk, Jungdon; Yun, Young Jun; Jung, Ha-Kyun; Choi, Sungho

2014-02-01

350

Preparation of activated carbon from date pits: Effect of the activation agent and liquid phase oxidation  

Microsoft Academic Search

Two series of activated carbons have been prepared from date pits; series C, using carbon dioxide as activating agent, and series S, prepared by activation with steam under the same experimental conditions. The obtained samples were oxidized with nitric acid in order to introduce more oxygen surface groups. The surface area and porosity of the parent and oxidized activated carbons

Meriem Belhachemi; Rachel V. R. A. Rios; Fatima Addoun; Joaquín Silvestre-Albero; Antonio Sepúlveda-Escribano; Francisco Rodríguez-Reinoso

2009-01-01

351

Characterization of activated carbons from oil-palm shell by CO2 activation with no holding carbonization temperature.  

PubMed

Activated carbons can be produced from different precursors, including coals of different ranks, and lignocellulosic materials, by physical or chemical activation processes. The objective of this paper is to characterize oil-palm shells, as a biomass byproduct from palm-oil mills which were converted into activated carbons by nitrogen pyrolysis followed by CO2 activation. The effects of no holding peak pyrolysis temperature on the physical characteristics of the activated carbons are studied. The BET surface area of the activated carbon is investigated using N2 adsorption at 77 K with selected temperatures of 500, 600, and 700°C. These pyrolysis conditions for preparing the activated carbons are found to yield higher BET surface area at a pyrolysis temperature of 700°C compared to selected commercial activated carbon. The activated carbons thus result in well-developed porosities and predominantly microporosities. By using this activation method, significant improvement can be obtained in the surface characteristics of the activated carbons. Thus this study shows that the preparation time can be shortened while better results of activated carbon can be produced. PMID:23737721

Herawan, S G; Hadi, M S; Ayob, Md R; Putra, A

2013-01-01

352

Characterization of Activated Carbons from Oil-Palm Shell by CO2 Activation with No Holding Carbonization Temperature  

PubMed Central

Activated carbons can be produced from different precursors, including coals of different ranks, and lignocellulosic materials, by physical or chemical activation processes. The objective of this paper is to characterize oil-palm shells, as a biomass byproduct from palm-oil mills which were converted into activated carbons by nitrogen pyrolysis followed by CO2 activation. The effects of no holding peak pyrolysis temperature on the physical characteristics of the activated carbons are studied. The BET surface area of the activated carbon is investigated using N2 adsorption at 77?K with selected temperatures of 500, 600, and 700°C. These pyrolysis conditions for preparing the activated carbons are found to yield higher BET surface area at a pyrolysis temperature of 700°C compared to selected commercial activated carbon. The activated carbons thus result in well-developed porosities and predominantly microporosities. By using this activation method, significant improvement can be obtained in the surface characteristics of the activated carbons. Thus this study shows that the preparation time can be shortened while better results of activated carbon can be produced. PMID:23737721

Herawan, S. G.; Hadi, M. S.; Ayob, Md. R.; Putra, A.

2013-01-01

353

Capturing nitrosamines in tobacco-extract solution by hydrophobic mesoporous silica.  

PubMed

Adsorption of tobacco-specific nitrosamines (TSNA) by the functionalized MCM-48 mesoporous silica in tobacco-extract solution was studied using batch experiments, in order to explore the new strategy enhancing the efficiency of molecular sieve in the solution with complex composition. The techniques of XRD, N(2) adsorption-desorption at 77K, (29)Si MAS NMR, (27)Al MAS NMR and TG-DSC together with FTIR were used to inspect the mesoporous adsorbents. The hydrophobic character of adsorbent is crucial for the adsorption of TSNA in aqueous solution, and the organic 3-chloropropyltriethoxysilane (CPTES) was employed to functionalize the ordered porous silica through direct co-condensation and post-synthesis grafting methods. Besides, aluminum is also incorporated into the framework of MCM-48 to enhance the adsorption capability of nitrosamines. As the result, about 70% of TSNA can be removed by the chloropropyl-modified Al-containing mesoporous silica, obviously exceeded that by activated carbon, offering the new efficient adsorbents for environment protection. PMID:19717229

Wei, Feng; Yang, Jia Yuan; Gao, Ling; Gu, Fang Na; Zhu, Jian Hua

2009-12-30

354

Synthesis of mesoporous nano-TiO 2 doped with Sn by auto-assembly method and photo-catalytic property  

Microsoft Academic Search

A series of mesoporous nano-TiO2 material doped with Sn are synthesized by a homogenous precipitation method aided by microwave heating, using TiCl4 and SnClm4 as raw materials, urea as precipitator, active carbon as templet, and soluble starch as anti- agglomerating reagent. XRD\\u000a results show that the precursor exists in the amorphous phase, and transforms to anatase structure above 400°C. TEM

Meihong Zhang; Shiwen Ding; Zhenxing Wang; Yuzhuo Zhang

2005-01-01

355

Co-production of activated carbon, fuel-gas, and oil from the pyrolysis of corncob mixtures with wet and dried sewage sludge.  

PubMed

This study explored the amount and composition of pyrolysis gas and oil derived from wet material or dried material during the preparation of sludge-corncob activated carbon, and evaluated the physicochemical and surface properties of the obtained two types of sludge-corncob-activated carbons. For wet material, owing to the presence of water, the yields of sludge-corncob activated carbon and the oil fraction slightly decreased while the yield of gases increased. The main pyrolysis gas compounds were H2 and CO2, and more H2 was released from wet material than dried material, whereas the opposite holds for CO2. Heterocyclics, nitriles, organic acids, and steroids were the major components of pyrolysis oil. Furthermore, the presence of water in wet material reduced the yield of polycyclic aromatic hydrocarbons from 6.76% to 5.43%. The yield of furfural, one of heterocyclics, increased sharply from 3.51% to 21.4%, which could be explained by the enhanced hydrolysis of corncob. In addition, the surface or chemical properties of the two sludge-corncob activated carbons were almost not affected by the moisture content of the raw material, although their mesopore volume and diameter were different. In addition, the adsorption capacities of the two sludge-corncob activated carbons towards Pb and nitrobenzene were nearly identical. PMID:24951551

Shao, Linlin; Jiang, Wenbo; Feng, Li; Zhang, Liqiu

2014-06-18

356

Efficient visible-light photocatalytic activity by band alignment in mesoporous ternary polyoxometalate-Ag2S-CdS semiconductors  

NASA Astrophysics Data System (ADS)

Porous multicomponent semiconductor materials show improved photocatalytic performance due to the large and accessible pore surface area and high charge separation efficiency. Here we report the synthesis of well-ordered porous polyoxometalate (POM)-Ag2S-CdS hybrid mesostructures featuring a controllable composition and high photocatalytic activity via a two-step hard-templating and topotactic ion-exchange chemical process. Ag2S compounds and polyoxometalate cluster anions with different reduction potentials, such as PW12O403-, SiW12O404- and PMo12O403-, were employed as electron acceptors in these ternary heterojunction photocatalysts. Characterization by small-angle X-ray scattering, X-ray diffraction, transmission electron microscopy and N2 physisorption measurements showed hexagonal arrays of POM-Ag2S-CdS hybrid nanorods with large internal BET surface areas and uniform mesopores. The Keggin structure of the incorporated POM clusters was also verified by elemental X-ray spectroscopy microanalysis, infrared and diffuse-reflectance ultraviolet-visible spectroscopy. These new porous materials were implemented as visible-light-driven photocatalysts, displaying exceptional high activity in aerobic oxidation of various para-substituted benzyl alcohols to the corresponding carbonyl compounds. Our experiments show that the spatial separation of photogenerated electrons and holes at CdS through the potential gradient along the CdS-Ag2S-POM interfaces is responsible for the increased photocatalytic activity.Porous multicomponent semiconductor materials show improved photocatalytic performance due to the large and accessible pore surface area and high charge separation efficiency. Here we report the synthesis of well-ordered porous polyoxometalate (POM)-Ag2S-CdS hybrid mesostructures featuring a controllable composition and high photocatalytic activity via a two-step hard-templating and topotactic ion-exchange chemical process. Ag2S compounds and polyoxometalate cluster anions with different reduction potentials, such as PW12O403-, SiW12O404- and PMo12O403-, were employed as electron acceptors in these ternary heterojunction photocatalysts. Characterization by small-angle X-ray scattering, X-ray diffraction, transmission electron microscopy and N2 physisorption measurements showed hexagonal arrays of POM-Ag2S-CdS hybrid nanorods with large internal BET surface areas and uniform mesopores. The Keggin structure of the incorporated POM clusters was also verified by elemental X-ray spectroscopy microanalysis, infrared and diffuse-reflectance ultraviolet-visible spectroscopy. These new porous materials were implemented as visible-light-driven photocatalysts, displaying exceptional high activity in aerobic oxidation of various para-substituted benzyl alcohols to the corresponding carbonyl compounds. Our experiments show that the spatial separation of photogenerated electrons and holes at CdS through the potential gradient along the CdS-Ag2S-POM interfaces is responsible for the increased photocatalytic activity. Electronic supplementary information (ESI) available: EDS spectra of STA/CdS and STA/Ag2S/CdS samples, SAXS patterns and N2 physisorption isotherms of SBA-15 silica, IR spectra of meso-CdS and POM-Ag2S-CdS materials, catalytic data of the as-prepared CdS based mesostructures and TiO2 (Degussa P25) nanoparticles, PL spectra of meso-CdS, Ag2S-CdS, CuS/CdS and STA/Ag2S/CdS samples, N2 physisorption isotherms of b-STA/Ag2S/CdS and STA/CuS/CdS, 1H NMR spectra of 8 oxidation products, and EDS and IR spectra and N2 physisorption isotherms of the reused STA/Ag2S/CdS catalyst. See DOI: 10.1039/c4nr01094a

Kornarakis, I.; Lykakis, I. N.; Vordos, N.; Armatas, G. S.

2014-07-01

357

Activated Carbon Composites for Air Separation  

SciTech Connect

Coal-derived synthesis gas is a potential major source of hydrogen for fuel cells. Oxygen-blown coal gasification is an efficient approach to achieving the goal of producing hydrogen from coal, but a cost-effective means of enriching O2 concentration in air is required. A key objective of this project is to assess the utility of a system that exploits porous carbon materials and electrical swing adsorption to produce an O2-enriched air stream for coal gasification. As a complement to O2 and N2 adsorption measurements, CO2 was used as a more sensitive probe molecule for the characterization of molecular sieving effects. To further enhance the potential of activated carbon composite materials for air separation, work was implemented on incorporating a novel twist into the system; namely the addition of a magnetic field to influence O2 adsorption, which is accompanied by a transition between the paramagnetic and diamagnetic states. The preliminary findings in this respect are discussed.

Baker, Frederick S [ORNL; Contescu, Cristian I [ORNL; Tsouris, Costas [ORNL; Burchell, Timothy D [ORNL

2011-09-01

358

Mesoporous aluminum phosphite  

NASA Astrophysics Data System (ADS)

High surface area pure mesoporous aluminum-phosphorus oxide-based derivatives have been synthesized through an S +I - 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 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.

El Haskouri, Jamal; Pérez-Cabero, Mónica; Guillem, Carmen; Latorre, Julio; Beltrán, Aurelio; Beltrán, Daniel; Amorós, Pedro

2009-08-01

359

Drug Loading of Mesoporous Silicon  

NASA Astrophysics Data System (ADS)

The nanostructuring of crystalline solids with low aqueous solubilities by their incorporation into mesoporous host materials is one route to improve the bioavailability of such solids. Earlier studies suggest that mesoporous Si (PSi), with pore widths in the range of 5-50 nm, is a candidate for such an approach. In this presentation, we describe efforts to load curcumin into free-standing microparticles of PSi. Curcumin is a compound extracted from turmeric root, which is an ingredient of curry. Curucmin has shown activity against selected cancer cell lines, bacteria, and other medical conditions. However, curcumin has a very low bioavailability due to its extremely low water solubility (0.6?g/mL). Incorporation of curcumin was achieved by straightforward loading of the molten solid at 185^oC. Loading experiments were performed using PSi particles of two different size ranges, 45-75 ?m and 150-250 ?m. Longer loading times and ratio of curcumin to PSi leads to a higher percentage of loaded curcumin in both PSi particle sizes (as determined by weight difference). The extent of curcumin crystallinity was assessed by x-ray diffraction (XRD). The solubility and release kinetics of loaded curcumin from the PSi was determined by extraction into water at 37^oC, with analysis using UV-VIS spectrometry.

Moffitt, Anne; Coffer, Jeff; Wang, Mengjia

2011-03-01

360

Enhanced Cellular Activation with Single Walled Carbon Nanotube Bundles  

E-print Network

Enhanced Cellular Activation with Single Walled Carbon Nanotube Bundles Presenting Antibody Stimuli the body using single walled carbon nanotube (SWNT) bundles presenting antibody stimuli. Owing to the large of lymphocytes, useful for basic science applications and clinical immunotherapy. Single walled carbon nanotubes

Fahmy, Tarek

361

High-pressure-activated carbon tetrachloride decomposition  

NASA Astrophysics Data System (ADS)

The pressure-induced molecular dissociation as one of the fundamental problems in physical sciences has aroused many theoretical and experimental studies. Here, using a newly developed particle swarm optimization algorithm, we investigate the high-pressure-induced molecular dissociation. The results show that the carbon tetrachloride (CCl4) is unstable and dissociates into C2Cl6 and Cl2 under approximately 120 GPa and more. The dissociation is confirmed by the lattice dynamic calculations and electronic structure of the Pa3 structure with pressure evolution. The dissociation pressure is far larger than that in the case of high temperature, indicating that the temperature effectively reduces the activation barrier of the dissociation reaction of CCl4. This research improves the understanding of the dissociation reactions of CCl4 and other halogen compounds under high pressures.

Chen, Yuan-Zheng; Zhou, Mi; Sun, Mei-Jiao; Li, Zuo-Wei; Sun, Cheng-Lin

2014-02-01

362

Impact of Pt loading methods over mesoporous-assembled TiO{sub 2}–ZrO{sub 2} mixed oxide nanocrystal on photocatalytic dye-sensitized H{sub 2} production activity  

SciTech Connect

Graphical abstract: The Pt loading on the synthesized mesoporous-assembled 0.95TiO{sub 2}–0.05ZrO{sub 2} mixed oxide nanocrystal photocatalyst was comparatively investigated by two methods: single-step sol–gel (SSSG) and photochemical deposition (PCD). The Pt loading by the PCD method was found to be superior to that by the SSSG method in enhancing photocatalytic sensitized hydrogen production under visible light irradiation. The Pt loading amount and PCD conditions, i.e. light irradiation time and light intensity, also had a strong effect on the photocatalytic hydrogen production activity. Highlights: ? Pt-loaded mesoporous-assembled 0.95TiO{sub 2}–0.05ZrO{sub 2} nanocrystals were synthesized. ? Pt loading was performed by single-step sol–gel and photochemical deposition. ? Pt loading by photochemical deposition more enhanced photocatalytic H{sub 2} production. ? Pt loading amount and photochemical deposition conditions were optimized. -- Abstract: In this work, the photocatalytic water splitting under visible light irradiation for hydrogen production was investigated by using Eosin Y-sensitized Pt-loaded mesoporous-assembled TiO{sub 2}–ZrO{sub 2} mixed oxide nanocrystal photocatalysts. The mesoporous-assembled TiO{sub 2}–ZrO{sub 2} mixed oxide with the TiO{sub 2}-to-ZrO{sub 2} molar ratio of 95:5 (i.e. 0.95TiO{sub 2}–0.05ZrO{sub 2}) was synthesized by using a sol–gel process with the aid of a structure-directing surfactant. The Pt loading was comparatively performed via two different effective methods: single-step sol–gel (SSSG) and photochemical deposition (PCD). The synthesized photocatalysts were methodically characterized by N{sub 2} adsorption–desorption, XRD, UV–visible spectroscopy, SEM–EDX, TEM–EDX, TPR, and H{sub 2} chemisorption analyses. The results revealed that the Pt loading by the PCD method greatly enhanced the photocatalytic hydrogen production activity of the synthesized mesoporous-assembled 0.95TiO{sub 2}–0.05ZrO{sub 2} mixed oxide photocatalyst more than that by the SSSG method. The optimum Pt loading by the PCD method was experimentally observed at 0.5 wt.%, which was well associated with the maximum Pt dispersion. In addition, the PCD conditions, i.e. UV light irradiation time and UV light intensity, were investigated and optimized to be 2 h and 44 W, respectively.

Sreethawong, Thammanoon, E-mail: tsreethawong@hotmail.com [Baan Klangmuang Luzern, Soi On-nut 46, Sukhumvit 77 Road, Suanluang, Bangkok 10250 (Thailand)] [Baan Klangmuang Luzern, Soi On-nut 46, Sukhumvit 77 Road, Suanluang, Bangkok 10250 (Thailand); Yoshikawa, Susumu [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)] [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)

2012-06-15

363

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

364

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

365

Record Methane Storage in Monolithic and Powdered Activated Carbons  

NASA Astrophysics Data System (ADS)

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 and volumetrically. Record methane storage capacities of 250 g CH4/kg carbon and 130 g CH4/liter carbon at 35 bar and 293 K have been achieved. BET surface area, porosity, and pore size distributions were measured from sub-critical nitrogen isotherms. Pore entrances were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A prototype adsorbed natural gas (ANG) tank, loaded with carbon monoliths, was tested in Kansas City.

Soo, Yuchoong; Nordwald, E.; Hester, B.; Romanos, J.; Isaacson, B.; Stalla, D.; Moore, D.; Kraus, M.; Burress, J.; Dohnke, E.; Pfeifer, P.

2010-03-01

366

Mechanistic Investigation of Catalytic Carbon-Carbon Bond Activation and Formation by Platinum and Palladium Phosphine  

E-print Network

Mechanistic Investigation of Catalytic Carbon-Carbon Bond Activation and Formation by Platinum impede their development. First, the metal- carbon bond resulting from C-C insertion has been calculated often results in thermal decomposition of the metal complex prior to C-C cleavage. To date, most

Jones, William D.

367

Preparation of macroporous carbon nanofibers with macroscopic openings in the surfaces and their applications  

E-print Network

of mesoporous carbon materials by templating [4], there have been significant advances in the design of porous carbon materials [2]. Templating against mesoporous silica or self-assembled block copolymers opened a good possibility toward industrial procedures to obtain mesoporous carbon materials [5

Kim, Young-Rok

368

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

369

Synthesis of fluorescent carbon nanoparticles directly from active carbon via a one-step ultrasonic treatment  

SciTech Connect

Water-soluble fluorescent carbon nanoparticles were synthesized directly from active carbon by a one-step hydrogen peroxide-assisted ultrasonic treatment. The carbon nanoparticles were characterized by transmission electron microscopy, optical fluorescent microscopy, fluorescent spectroscopy, Fourier transform infrared spectroscopy and ultraviolet-visible spectrophotometer. The results showed that the surface of carbon nanoparticles was rich of hydroxyl groups resulting in high hydrophilicity. The carbon nanoparticles could emit bright and colorful photoluminescence covering the entire visible-to-near infrared spectral range. Furthermore, these carbon nanoparticles also had excellent up-conversion fluorescent properties.

Li, Haitao; He, Xiaodie [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China)] [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Liu, Yang, E-mail: yangl@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China) [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Department of Chemistry, Northeast Normal University, Changchun 130024 (China); Yu, Hang [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China)] [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China) [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Department of Chemistry, Northeast Normal University, Changchun 130024 (China); Lee, Shuit-Tong [Center of Super-Diamond and Advanced Films (COSADF), City University of Hong Kong, Hong Kong SAR (China)] [Center of Super-Diamond and Advanced Films (COSADF), City University of Hong Kong, Hong Kong SAR (China)

2011-01-15

370

Electrochemical studies on nanometal oxide-activated carbon composite electrodes for aqueous supercapacitors  

NASA Astrophysics Data System (ADS)

In present study, the electrochemical performance of eco-friendly and cost-effective titanium oxide (TiO2)-based and zinc oxide-based nanocomposite electrodes were studied in neutral aqueous Na2SO3 electrolyte, respectively. The electrochemical properties of these composite electrodes were studied using cyclic voltammetry (CV), galvanostatic charge-discharge (CD) and electrochemical impedance spectroscopy (EIS). The experimental results reveal that these two nanocomposite electrodes achieve the highest specific capacitance at fairly low oxide loading onto activated carbon (AC) electrodes, respectively. Considerable enhancement of the electrochemical properties of TiO2/AC and ZnO/AC nanocomposite electrodes is achieved via synergistic effects contributed from the nanostructured metal oxides and the high surface area mesoporous AC. Cations and anions from metal oxides and aqueous electrolyte such as Ti4+, Zn2+, Na+ and SO32- can occupy some pores within the high-surface-area AC electrodes, forming the electric double layer at the electrode-electrolyte interface. Additionally, both TiO2 and ZnO nanoparticles can provide favourable surface adsorption sites for SO32- anions which subsequently facilitate the faradaic processes for pseudocapacitive effect. These two systems provide the low cost material electrodes and the low environmental impact electrolyte which offer the increased charge storage without compromising charge storage kinetics.

Ho, Mui Yen; Khiew, Poi Sim; Isa, Dino; Chiu, Wee Siong

2014-11-01

371

Mesoporous Ta(3)N(5) microspheres prepared from a high-surface-area, microporous, amorphous precursor and their visible-light-driven photocatalytic activity.  

PubMed

A light Ta3N5: Mesoporous Ta3N5 microspheres were synthesized by thermally nitriding a high-surface-area, microporous, amorphous Ta2O5 precursor at 750?°C, which is lower than the 900?°C needed for the complete nitridation of micrometer-sized Ta2O5 powder. The mesoporous Ta3N5 microspheres show significantly enhanced visible-light photoactivity in the degradation of methylene blue (MB) compared with similar photocatalysts reported under similar conditions. PMID:24175337

Cao, Jing; Ren, Ling; Li, Na; Hu, Changwen; Cao, Minhua

2013-09-16

372

Activated Carbon Modified with Copper for Adsorption of Propanethiol  

PubMed Central

Activated carbons were characterized texturally and chemically before and after treatment, using surface area determination in the BET model, Boehm titration, TPR, DRX and immersion calorimetry. The adsorption capacity and the kinetics of sulphur compound removal were determined by gas chromatography. It was established that the propanethiol retention capacity is dependent on the number of oxygenated groups generated on the activated carbon surface and that activated carbon modified with CuO at 0.25 M shows the highest retention of propanethiol. Additionally is proposed a mechanism of decomposition of propenothiol with carbon-copper system. PMID:20479992

Moreno-Piraján, Juan Carlos; Tirano, Joaquín; Salamanca, Brisa; Giraldo, Liliana

2010-01-01

373

Heterogeneous mercury reaction chemistry on activated carbon.  

PubMed

Experimental and theory-based investigations have been carried out on the oxidation and adsorption mechanism of mercury (Hg) on brominated activated carbon (AC). Air containing parts per billion concentrations of Hg was passed over a packed-bed reactor with varying sorbent materials at 140 and 30 degrees C. Through X-ray photoelectron spectroscopy surface characterization studies it was found that Hg adsorption is primarily associated with bromine (Br) on the surface, but that it may be possible for surface-bound oxygen (O) to play a role in determining the stability of adsorbed Hg. In addition to surface characterization experiments, the interaction of Hg with brominated AC was studied using plane-wave density functional theory. Various configurations of hydrogen, O, Br, and Hg on the zigzag edge sites of graphene were investigated, and although Hg-Br complexes were found to be stable on the surface, the most stable configurations found were those with Hg adjacent to O. The Hg-carbon (C) bond length ranged from 2.26 to 2.34 A and is approximately 0.1 A shorter when O is a nearest-neighbor atom rather than a next-nearest neighbor, resulting in increased stability of the given configuration and overall tighter Hg-C binding. Through a density of states analysis, Hg was found to gain electron density in the six p-states after adsorption and was found to donate electron density from the five s-states, thereby leading to an oxidized surface-bound Hg complex. PMID:21516937

Wilcox, Jennifer; Sasmaz, Erdem; Kirchofer, Abby; Lee, Sang-Sup

2011-04-01

374

[Flue gas desulfurization by a novel biomass activated carbon].  

PubMed

A novel biomass columnar activated carbon was prepared from walnut shell and pyrolusite was added as a catalyst. The activated carbon prepared was used for flue gas desulphurization in a fixed-bed reactor with 16 g of activated carbon. The impact of operating parameters such as SO2 inlet concentration, space velocity, bed temperature, moisture content and O2 concentration on the desulfurization efficiency of activated carbon was investigated. The results showed that both the breakthrough sulfur capacity and breakthrough time of activated carbon decreased with the increase of SO2 inlet concentration within the range of 0.1% -0.3%. The breakthrough sulfur capacity deceased with the increase of space velocity, with optimal space velocity of 600 h(-1). The optimal bed temperature was 80 degrees C, and the desulfurization efficiency can be reduced if the temperature continue to increase. The presence of moisture and oxygen greatly promoted the adsorption of SO2 onto the activated carbon. The best moisture content was 10%. When the oxygen concentrations were between 10% and 13%, the desulfurization performance of activated carbon was the highest. Under the optimal operating conditions, the sulfur capacity of activated carbon was 252 mg x g(-1), and the breakthrough time was up to 26 h when the SO2 inlet concentration was 0.2%. PMID:23798152

Liu, Jie-Ling; Tang, Zheng-Guang; Chen, Jie; Jiang, Wen-Ju; Jiang, Xia

2013-04-01

375

Acoustical Evaluation of Carbonized and Activated Cotton Nonwovens  

Technology Transfer Automated Retrieval System (TEKTRAN)

The process of manufacturing a carbonized and activated nonwoven made by cotton fiber was investigated in this paper. The study was focused on the acoustic application and nonwoven composites with cotton nonwoven as a base layer and glass fiber nonwoven, cotton nonwoven, and carbonized and activated...

376

The effect of carbonization heating rate on charcoal and active carbon yields  

SciTech Connect

The thermal decomposition of white oak chips was investigated by pyrolyzing 1-k samples at atmospheric pressure in an electrically-heated batch reactor using five carbonization heating rates from 0.98 to 9.44{degrees}C/min, and a maximum temperature of 490{degrees}C. The resulting charcoals were then activated with steam in a second batch reactor. Iodine number was used as a measure of the sorptive capacity of the active carbon. Charcoal yields decreased as the carbonization heating rate increased, particularly for rates less than about VC/min. Active carbon yields decreased and iodine numbers increased as the severity of gasification increased. For carbonization heating rates greater than about 4{degrees}C/min, the active carbon yield for a given iodine number was essentially independent of the heating rate.

Martin, C.E.; Purdy, K.R.; Dubayeh, S.A.; Kerr, C.P.; Garr, T.D. [Tennessee Technological Univ., Cookville, TN (United States)

1991-12-31

377

Characterization of activated carbon, graphitized carbon fibers and synthetic diamond powder using TPD and DRIFTS  

Microsoft Academic Search

A high surface area activated carbon, graphitized carbon fibers and synthetic diamond powder were characterized by X-ray diffraction, temperature-programmed desorption and diffuse reflectance infrared (IR) spectroscopy (DRIFTS). The activated carbon was analyzed as received as well as after either a nitric acid treatment to introduce oxygen functional groups on its surface or a high temperature treatment (HTT) in H2 at

A. Dandekar; R. T. K. Baker; M. A. Vannice

1998-01-01

378

Microbial Enzyme Activity and Carbon Cycling in Grassland Soil Fractions  

NASA Astrophysics Data System (ADS)

Extracellular enzymes are necessary to degrade complex organic compounds present in soils. Using physical fractionation procedures, we tested whether old soil carbon is spatially isolated from degradative enzymes across a prairie restoration chronosequence in Illinois, USA. We found that carbon-degrading enzymes were abundant in all soil fractions, including macroaggregates, microaggregates, and the clay fraction, which contains carbon with a mean residence time of ~200 years. The activities of two cellulose-degrading enzymes and a chitin-degrading enzyme were 2-10 times greater in organic matter fractions than in bulk soil, consistent with the rapid turnover of these fractions. Polyphenol oxidase activity was 3 times greater in the clay fraction than in the bulk soil, despite very slow carbon turnover in this fraction. Changes in enzyme activity across the restoration chronosequence were small once adjusted for increases in soil carbon concentration, although polyphenol oxidase activity per unit carbon declined by 50% in native prairie versus cultivated soil. These results are consistent with a `two-pool' model of enzyme and carbon turnover in grassland soils. In light organic matter fractions, enzyme production and carbon turnover both occur rapidly. However, in mineral-dominated fractions, both enzymes and their carbon substrates are immobilized on mineral surfaces, leading to slow turnover. Soil carbon accumulation in the clay fraction and across the prairie restoration chronosequence probably reflects increasing physical isolation of enzymes and substrates on the molecular scale, rather than the micron to millimeter scale.

Allison, S. D.; Jastrow, J. D.

2004-12-01

379

Enhanced electrical capacitance of porous carbons by nitrogen enrichment and control of the pore structure  

Microsoft Academic Search

A series of nitrogen-containing porous carbons were produced through KOH activation of a nitrogen-enriched carbon prepared in the pores of a mesoporous silica. Nitrogen sorption at 77K showed that the pore volumes increased gradually along with an increasing mass ratio of KOH\\/carbon. The sample with the highest pore volume of 2.68mlg?1 was obtained when the mass ratio was 5. Cyclic

Jinhua Jiang; Qiuming Gao; Kaisheng Xia; Juan Hu

2009-01-01

380

Selecting activated carbon for water and wastewater treatability studies  

SciTech Connect

A series of follow-up investigations were performed to produce data for improving the four-indicator carbon selection method that we developed to identify high-potential activated carbons effective for removing specific organic water pollutants. The carbon's pore structure and surface chemistry are dependent on the raw material and the activation process. Coconut carbons have relatively more small pores than large pores; coal and apricot nutshell/walnut shell fruit carbons have the desirable pore structures for removing adsorbates of all sizes. Chemical activation, excessive activation, and/or thermal reactivation enlarge small pores, resulting in reduced phenol number and higher tannic acid number. Activated carbon's phenol, iodine, methylene blue, and tannic acid numbers are convenient indicators of its surface area and pore volume of pore diameters < 10, 10-15, 15-28, and > 28 angstrom, respectively. The phenol number of a carbon is also a good indicator of its surface acidity of oxygen-containing organic functional groups that affect the adsorptive capacity for aromatic and other small polar organics. The tannic acid number is an indicator of carbon's capacity for large, high-molecular-weight natural organic precursors of disinfection by-products in water treatment. The experimental results for removing nitrobenzene, methyl-tert-butyl ether, 4,4-bisphenol, humic acid, and the organic constituents of a biologically treated coking-plant effluent have demonstrated the effectiveness of this capacity-indicator-based method of carbon selection.

Zhang, W.; Chang, Q.G.; Liu, W.D.; Li, B.J.; Jiang, W.X.; Fu, L.J.; Ying, W.C. [East China University of Chemical Technology, Shanghai (China)

2007-10-15

381

Fractal analysis of granular activated carbons using isotherm data  

SciTech Connect

Utilization of adsorption on solid surfaces was exercised for the first time in 1785. Practical application of unactivated carbon filters, and powdered carbon were first demonstrated in the American water treatment plant, and a municipal treatment plant in New Jersey, in 1883 and 1930, respectively. The use of activated carbon became widespread in the next few decades. At present, adsorption on carbons has a wide spread application in water treatment and removal of taste, odor, removal of synthetic organic chemicals, color-forming organics, and desinfection by-products and their naturally occurring precursors. This paper presents an analysis of the surface fractal dimension and adsorption capacity of a group of carbons.

Khalili, N.R.; Pan, M. [Illinois Institute of Technology, Chicago, IL (United States). Dept. of Chemical and Environmental Engineering; Sandi, G. [Argonne National Lab., IL (United States)

1997-08-01

382

Activation of carbonic anhydrase II by active-site incorporation of histidine analogs  

E-print Network

Activation of carbonic anhydrase II by active-site incorporation of histidine analogs Ileana Elder of CO2 catalyzed by human carbonic anhydrase II (HCA II) is accompanied by proton transfer from the zinc the largest values of kcat=Km observed for a carbonic anhydrase. Ã? 2003 Elsevier Inc. All rights reserved

Viola, Ronald

383

Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of ?-electron energy to investigate the role of ?-? electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects appear to be more pronounced with activated carbon materials, perhaps due to smaller pore sizes or larger adsorption surface areas in small pores.

Brooks, A. J.; Lim, Hyung-nam; Kilduff, James E.

2012-07-01

384

Soil Inorganic Carbon in Deserts: Active Carbon Sink or Inert Reservoir?  

NASA Astrophysics Data System (ADS)

Soil inorganic carbon is the third largest C pool in the active global carbon cycle, containing at least 800 petagrams of carbon. Although carbonate dissolution-precipitation reactions have been understood for over a century, the role of soil inorganic carbon in carbon sequestration, and in particular pedogenic carbonate, is a deceptively complex process because it involves interdependent connections among climate, plants, microorganisms, silicate minerals, soil moisture, pH, and Ca supply via rain, dust, or in situ weathering. An understanding of soil inorganic carbon as a sink or reservoir also requires examination of the system at local to continental scales and at seasonal to millennial time scales. In desert soils studied in North America, carbon isotope ratios and radiocarbon dates were measured in combination with electron microscopy, lab and field experiments with biological calcite formation, and field measurements of carbon dioxide emissions. These investigations reveal that soil inorganic carbon is both an active sink and a inert reservoir depending on the spatial and temporal scale and source of calcium.

Monger, H. C.; Cole, D. R.

2011-12-01

385

RESEARCH PAPER Facile synthesis of porous-carbon/LiFePO4 nanocomposites  

E-print Network

Program, Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul. The combination of nanosized active materials and mesoporous carbon is advantageous for facile diffusion of Li iron phosphate has received extensive interest as a promising cathode material since the first report

Park, Byungwoo

386

Select metal adsorption by activated carbon made from peanut shells.  

PubMed

Agricultural by-products, such as peanut shells, contribute large quantities of lignocellulosic waste to the environment each growing season; but few, if any, value-added uses exist for their disposal. The objective of this study was to convert peanut shells to activated carbons for use in adsorption of select metal ions, namely, cadmium (Cd2+), copper (Cu2+), lead (Pb2+), nickel (Ni2+) and zinc (Zn2+). Milled peanut shells were pyrolyzed in an inert atmosphere of nitrogen gas, and then activated with steam at different activation times. Following pyrolysis and activation, the carbons underwent air oxidation. The prepared carbons were evaluated either for adsorption efficiency or adsorption capacity; and these parameters were compared to the same parameters obtained from three commercial carbons, namely, DARCO 12x20, NORIT C GRAN and MINOTAUR. One of the peanut shell-based carbons had metal ion adsorption efficiencies greater than two of the three commercial carbons but somewhat less than but close to Minotaur. This study demonstrates that peanut shells can serve as a source for activated carbons with metal ion-removing potential and may serve as a replacement for coal-based commercial carbons in applications that warrant their use. PMID:16364633

Wilson, Kermit; Yang, Hong; Seo, Chung W; Marshall, Wayne E

2006-12-01

387

40 CFR 60.1330 - How do I monitor the injection rate of activated carbon?  

...monitor the injection rate of activated carbon? 60.1330 Section 60.1330 Protection...monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or...

2014-07-01

388

40 CFR 60.1820 - How do I monitor the injection rate of activated carbon?  

...monitor the injection rate of activated carbon? 60.1820 Section 60.1820 Protection...monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or...

2014-07-01

389

Activated carbon fibers and engineered forms from renewable resources  

DOEpatents

A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

Baker, Frederick S

2013-02-19

390

Synthesis and photocatalytic activity of mesoporous cerium doped TiO{sub 2} as visible light sensitive photocatalyst  

SciTech Connect

Graphical abstract: Cerium doped titania having optimum 5 wt% of cerium can decompose methylene blue and reduce selenium (IV) efficiently under visible light. Highlights: Black-Right-Pointing-Pointer Effect of cerium doping on the surface properties and visible light mediated photocatalytic reaction is studied. Black-Right-Pointing-Pointer Cerium doping increases the anatase phase stability, surface area (up to 137 m{sup 2}/g) and visible light absorption. Black-Right-Pointing-Pointer Importance of Ce{sup 3+}/Ce{sup 4+}, oxygen vacancy, surface area and crystallinity is correlated with improved catalytic activity. Black-Right-Pointing-Pointer Material with 5 wt% Ce is found to be most active photocatalyst for methylene blue decomposition and Se (IV) reduction. -- Abstract: Cerium doped titania materials were synthesized varying the cerium concentration from 0 to 10 wt%. Materials are characterised by XRD, TEM, XPS and N{sub 2} adsorption desorption method. Surface area and visible light absorption substantially increases and crystallite size decreases with the increasing cerium content. Cerium doping stabilizes the anatase phase and surface area even at 600 Degree-Sign C calcination. Photocatalytic activity towards methylene blue decomposition and selenium (IV) reduction is found to increase with the cerium content up to 5 wt% and then decreases. Materials calcined at 600 Degree-Sign C shows better activity than that calcined at 400 Degree-Sign C, even though surface area decreases. Anatase crystallinity mostly decides the photocatalytic activity rather than only surface area. It can be concluded that the optimum visible light absorption and oxygen vacancy with 5% cerium doping enhances the photocatalytic activity. In addition photocatalytic performance is found to depend on the presence of Ce{sup 4+}/Ce{sup 3+} rather than only visible light absorption.

Aman, Noor [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India)] [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Satapathy, P.K. [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India)] [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India); Mishra, T., E-mail: drtmishra@yahoo.com [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Mahato, M. [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India)] [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Das, N.N. [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India)] [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India)

2012-02-15

391

Activated carbon testing for the 200 area effluent treatment facility  

SciTech Connect

This report documents pilot and laboratory scale testing of activated carbon for use in the 200 Area Effluent Treatment Facility peroxide decomposer columns. Recommendations are made concerning column operating conditions and hardware design, the optimum type of carbon for use in the plant, and possible further studies.

Wagner, R.N.

1997-01-17

392

DESIGN AND CONSTRUCTION OF A MOBILE ACTIVATED CARBON REGENERATOR SYSTEM  

EPA Science Inventory

Activated carbon adsorption has become a standard procedure for the cleanup of contaminated water streams. To facilitate such cleanup at hazardous waste and spill sites, mobile carbon adsorption units have been constructed and are now in use. Their primary drawback is the logisti...

393

HARDWOOD-BASED GRANULAR ACTIVATED CARBON FOR METALS REMEDIATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Granular activated carbon is usually the adsorbent of choice for removing organic pollutants from air and water waste streams. Its ability to remove metal ions from aqueous media is considered secondary to its ability to remove organics. Only recently was a coal-based, commerical carbon (Minotaur,...

394

HARDWOOD-BASED GRANULAR ACTIVATED CARBON FOR METALS REMEDIATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Granular activated carbon is usually the adsorbent of choice for removing organic pollutants from air and water waste streams. Its ability to remove metal ions from aqueous media is considered secondary to its ability to remove organics. Only recently was a coal-based, commercial carbon (Minotaur) m...

395

HARDWOOD-BASED GRANULAR ACTIVATED CARBON FOR METALS REMEDIATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Granular activated carbon is usually the adsorbent of choice for removing organic pollutants from air and water waste streams. Its ability to remove metal ions from aqueous media is considered secondary to its ability to remove organics. Only recently was a coal-based, commercial carbon (Minotaur, C...

396

ELEMENTAL MERCURY CAPTURE BY ACTIVATED CARBON IN A FLOW REACTOR  

EPA Science Inventory

The paper gives results of bench-scale experiments in a flow reactor to simulate the entrained-flow capture of elemental mercury (Hgo) using solid sorbents. Adsorption of Hgo by a lignite-based activated carbon (Calgon FGD) was examined at different carbon/mercury (C/Hg) rat...

397

Immobilization of enzymes on activated carbon: selection and preparation of the carbon support.  

PubMed

Based upon its superior catalytic activity for H2O2 decomposition, a bituminous coal-based activated carbon was selected for investigations of pretreatment and enzyme immobilization methods. Pretreatments considered include acid washing, exposure to strong oxidizing agents, contact with concentrated peroxide solutions, nitration and amination, isothiocyanate derivatization, silanization, and stearic acid coating. Effects of these pretreatments on morphology and trace-metal content of the carbon pellets have been studied using scanning electron microscopy and dispersive analysis of x rays. Immobilization of glucoamylase by adsorption, glutaraldehyde crosslinking, and covalent attachment to carbon activated by water-soluble diimide or diazotization have been examined. These different enzyme-carbon catalysts have been characterized by their enzyme loading, enzyme activity, catalytic activity for H2O2 decomposition, or combinations of these measures of performance. PMID:106909

Cho, Y K; Bailey, J E

1979-03-01

398

Quality of poultry litter-derived granular activated carbon.  

PubMed

Utilization of poultry litter as a source material for generating activated carbon is a value-added and environmentally beneficial approach to recycling organic waste. In this study, the overall quality of poultry litter-derived granular activated carbon was systematically evaluated based on its various physical and chemical properties. Granular activated carbon generated from pelletized poultry litter following a typical steam-activation procedure possessed numerous micropores in the matrix. The product exhibited a mean particle diameter of 2.59 mm, an apparent density of 0.45 g cm(-3), a ball-pan hardness of 91.0, an iodine number of 454 mg g(-1), and a BET surface area of 403 m(2) g(-1). It contained high ash, nitrogen, phosphorus contents and the trace elements Cu, Zn, and As. Most of the nutrients and toxic elements were solidified and solution-unextractable. In general, poultry litter-based activated carbon demonstrated overall quality comparable to that of low-grade commercial activated carbon derived from coconut shell and bituminous coal. It is promising to use poultry litter as a feedstock to manufacture activated carbon for wastewater treatment. PMID:19703765

Qiu, Guannan; Guo, Mingxin

2010-01-01

399

Novel and mild synthetic strategy for the sulfonic Acid functionalization in periodic mesoporous ethenylene-silica.  

PubMed

A new postsynthetic method has been developed for sulfonic acid functionalization of hybrid periodic mesoporous organosilica (PMO) materials containing carbon-carbon double bonds (-C?C-) located in mesoporous wall structures. Hexagonal mesoporous ethenylene-silicas (HME) with different pore sizes were synthesized by using P123, Brij76, and Brij56 surfactants and investigated for postsynthetic functionalization. The present functionalization strategy involves epoxidation of double bonds at -5 °C followed by conversion of the resulting epoxide with bisulfite ions at 65 °C and involves neither the use of well-known mercaptol/H2O2 nor harsh concentrated H2SO4 reagents during the course of -C?C- functionalization. The epoxidation step plays a crucial role in determining the amount of -SO3H groups functionalized onto the silica support which is optimized with respect to different synthesis parameters. The ethenylene-silicas both before and after chemical modification were thoroughly characterized by powder XRD, TEM, N2 adsorption, Raman spectroscopy, 13C and 29Si MAS NMR, and catalytic test reactions. X-ray powder diffraction measurements and sorption data indicated that the mesostructure was intact during the postsynthetic chemical modification. Raman spectra exhibited two strong bands at 1567 and 1290 cm(-1) for ethenylene-silica attributed to -C?C and -C-H stretching vibrations, respectively; whereas after epoxidation and sulfonation, new bands were observed at 1215 and 1035 cm(-1) corresponding to the epoxide and -SO3 stretching vibrations, respectively. 13C CP MAS NMR of surfactant extracted ethenylene-silica exhibits a signal at 146 ppm along with signals at 16.4 and 17.4 ppm. The appearance of new signals at 47.7 and 46.5 ppm is attributed to carbon atom with ?C-OH and ?C-SO3H groups, respectively. 29Si MAS NMR spectra exclusively showed T2 and T3 species at -73 and -82 ppm, respectively both before and after chemical modification and negligible amount of Q3 or Q4 species confirms the stability of Si-C bonds during the functionalization. The sulfonic acid-functionalized mesoporous ethenylene-silicas show high catalytic activity in esterification of acetic acid with ethanol under liquid-phase reaction conditions. PMID:23484521

Sasidharan, Manickam; Bhaumik, Asim

2013-04-10

400

Carbon-Carbon Bond Activation in Pt(0)-Diphenylacetylene Complexes Bearing  

E-print Network

Carbon-Carbon Bond Activation in Pt(0)-Diphenylacetylene Complexes Bearing Chelating P,N- and P complexes bearing chelating P,N- or P,P-ligands and on the cleavage of the C(sp2)-C(sp) bond complexes bearing chelat- ing P,P-ligands. Thus, the reaction of 1 with 1 equiv bis- (diisopropylphosphino

Jones, William D.

401

GRANULAR ACTIVATED CARBON ADSORPTION AND INFRARED REACTIVATION: A CASE STUDY  

EPA Science Inventory

A study evaluated the effectiveness and cost of removing trace organic contaminants and surrogates from drinking water by granular activated carbon (GAC) adsorption. The effect of multiple reactivations of spent GAC was also evaluated. Results indicated that reactivated GAC eff...

402

Characteristics of activated carbons prepared from pistachio-nut shells by physical activation  

Microsoft Academic Search

Activated carbons were prepared from pistachio-nut shells, which are one type of lignocellulosic material, by a two-step physical method. The effects of the preparation variables on the activated carbon pore structure were studied, followed by the optimization of these operating parameters. It was found that the activation temperature and dwell time are the important parameters that affect the characteristics of

Ting Yang; Aik Chong Lua

2003-01-01

403

Preparation and characterization of activated carbon from date stones by physical activation with steam  

Microsoft Academic Search

Activated carbons are produced from wastes of Algerian date stones by pyrolysis and physical activation in the presence of water vapor into a heated fixed-bed reactor. The effect of pyrolysis temperature and activation hold time on textural and chemical surface properties of raw date stones and carbon materials produced are studied. As expected, the percentage yield decreases with increase of

Chafia Bouchelta; Mohamed Salah Medjram; Odile Bertrand; Je